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%% Papers Published
@article{fds167759,
Author = {E. C. Ellis and P.K. Haff},
Title = {Earth Science in the Anthropocene: New Era, New Paradigm,
New Responsibilities},
Journal = {EOS 40, 473},
Year = {2009},
Key = {fds167759}
}
%% Papers Published
@article{fds329153,
Author = {Zalasiewicz, J and Waters, CN and Summerhayes, CP and Wolfe, AP and Barnosky, AD and Cearreta, A and Crutzen, P and Ellis, E and Fairchild,
IJ and Gałuszka, A and Haff, P and Hajdas, I and Head, MJ and Ivar do Sul,
JA and Jeandel, C and Leinfelder, R and McNeill, JR and Neal, C and Odada,
E and Oreskes, N and Steffen, W and Syvitski, J and Vidas, D and Wagreich,
M and Williams, M},
Title = {The Working Group on the Anthropocene: Summary of evidence
and interim recommendations},
Journal = {Anthropocene},
Volume = {19},
Pages = {55-60},
Publisher = {Elsevier BV},
Year = {2017},
Month = {September},
url = {http://dx.doi.org/10.1016/j.ancene.2017.09.001},
Abstract = {Since 2009, the Working Group on the ‘Anthropocene’ (or,
commonly, AWG for Anthropocene Working Group), has been
critically analysing the case for formalization of this
proposed but still informal geological time unit. The study
to date has mainly involved establishing the overall nature
of the Anthropocene as a potential chronostratigraphic/geochronologic
unit, and exploring the stratigraphic proxies, including
several that are novel in geology, that might be applied to
its characterization and definition. A preliminary summary
of evidence and interim recommendations was presented by the
Working Group at the 35th International Geological Congress
in Cape Town, South Africa, in August 2016, together with
results of voting by members of the AWG indicating the
current balance of opinion on major questions surrounding
the Anthropocene. The majority opinion within the AWG holds
the Anthropocene to be stratigraphically real, and
recommends formalization at epoch/series rank based on a
mid-20th century boundary. Work is proceeding towards a
formal proposal based upon selection of an appropriate
Global boundary Stratotype Section and Point (GSSP), as well
as auxiliary stratotypes. Among the array of proxies that
might be used as a primary marker, anthropogenic
radionuclides associated with nuclear arms testing are the
most promising; potential secondary markers include plastic,
carbon isotope patterns and industrial fly ash. All these
proxies have excellent global or near-global correlation
potential in a wide variety of sedimentary bodies, both
marine and non-marine.},
Doi = {10.1016/j.ancene.2017.09.001},
Key = {fds329153}
}
@article{fds328732,
Author = {Haff, PK},
Title = {Being human in the Anthropocene},
Journal = {The Anthropocene Review},
Volume = {4},
Number = {2},
Pages = {103-109},
Publisher = {SAGE Publications},
Year = {2017},
Month = {August},
url = {http://dx.doi.org/10.1177/2053019617700875},
Abstract = {This essay aims to show how what is most intimately and
essentially human – our ideas, personal purposes,
feelings, and dreams – finds space for expression within
the autonomous, unfeeling, physical dynamics of the
technosphere – the defining system of the Anthropocene.
The approach adopted is based on systems science and aims to
avoid metaphysical assumptions about the nature and
importance of human values. A non-humanistic analysis of
human potential shows why the demands of the physical
technosphere on human behavior leave space for nominally
non-technospheric activities, such as the pursuit of
personal purposes. The dynamical perspective also highlights
the central role of humanistic pushback against
technospheric encroachment on the human domain.},
Doi = {10.1177/2053019617700875},
Key = {fds328732}
}
@article{fds326651,
Author = {Zalasiewicz, J and Williams, M and Waters, CN and Barnosky, AD and Palmesino, J and Rönnskog, AS and Edgeworth, M and Neal, C and Cearreta, A and Ellis, EC and Grinevald, J and Haff, P and Ivar do Sul,
JA and Jeandel, C and Leinfelder, R and McNeill, JR and Odada, E and Oreskes, N and Price, SJ and Revkin, A and Steffen, W and Summerhayes,
C and Vidas, D and Wing, S and Wolfe, AP},
Title = {Scale and diversity of the physical technosphere: A
geological perspective},
Journal = {The Anthropocene Review},
Volume = {4},
Number = {1},
Pages = {9-22},
Publisher = {SAGE Publications},
Year = {2017},
Month = {April},
url = {http://dx.doi.org/10.1177/2053019616677743},
Abstract = {We assess the scale and extent of the physical technosphere,
defined here as the summed material output of the
contemporary human enterprise. It includes active urban,
agricultural and marine components, used to sustain energy
and material flow for current human life, and a growing
residue layer, currently only in small part recycled back
into the active component. Preliminary estimates suggest a
technosphere mass of approximately 30 trillion tonnes (Tt),
which helps support a human biomass that, despite recent
growth, is ~5 orders of magnitude smaller. The physical
technosphere includes a large, rapidly growing diversity of
complex objects that are potential trace fossils or
‘technofossils’. If assessed on palaeontological
criteria, technofossil diversity already exceeds known
estimates of biological diversity as measured by richness,
far exceeds recognized fossil diversity, and may exceed
total biological diversity through Earth’s history. The
rapid transformation of much of Earth’s surface mass into
the technosphere and its myriad components underscores the
novelty of the current planetary transformation.},
Doi = {10.1177/2053019616677743},
Key = {fds326651}
}
@article{fds325787,
Author = {Zalasiewicz, J and Waters, CN and Wolfe, AP and Barnosky, AD and Cearreta, A and Edgeworth, M and Ellis, EC and Fairchild, IJ and Gradstein, FM and Grinevald, J and Haff, P and Head, MJ and do Sul, JAI and Jeandel, C and Leinfelder, R and McNeill, JR and Oreskes, N and Poirier,
C and Revkin, A and Richter, DDB and Steffen, W and Summerhayes, C and Syvitski, JPM and Vidas, D and Wagreich, M and Wing, S and Williams,
M},
Title = {Making the case for a formal Anthropocene Epoch: An analysis
of ongoing critiques},
Journal = {Newsletters on Stratigraphy},
Volume = {50},
Number = {2},
Pages = {205-226},
Publisher = {Schweizerbart},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1127/nos/2017/0385},
Abstract = {A range of published arguments against formalizing the
Anthropocene as a geological time unit have variously
suggested that it is a misleading term of non-stratigraphic
origin and usage, is based on insignificant temporal and
material stratigraphic content unlike that used to define
older geological time units, is focused on observation of
human history or speculation about the future rather than
geologically significant events, and is driven more by
politics than science. In response, we contend that the
Anthropocene is a functional term that has firm geological
grounding in a well-characterized stratigraphic record. This
record, although often lithologically thin, is laterally
extensive, rich in detail and already reflects substantial
elapsed (and in part irreversible) change to the Earth
System that is comparable to or greater in magnitude than
that of previous epoch-scale transitions. The Anthropocene
differs from previously defined epochs in reflecting
contemporary geological change, which in turn also leads to
the term's use over a wide range of social and political
discourse. Nevertheless, that use remains entirely distinct
from its demonstrable stratigraphic underpinning. Here we
respond to the arguments opposing the geological validity
and utility of the Anthropocene, and submit that a strong
case may be made for the Anthropocene to be treated as a
formal chronostratigraphic unit and added to the Geological
Time Scale.},
Doi = {10.1127/nos/2017/0385},
Key = {fds325787}
}
@article{fds323385,
Author = {Haff, PK},
Title = {Purpose in the Anthropocene: Dynamical role and physical
basis},
Journal = {Anthropocene},
Volume = {16},
Pages = {54-60},
Publisher = {Elsevier BV},
Year = {2016},
Month = {December},
url = {http://dx.doi.org/10.1016/j.ancene.2016.07.002},
Abstract = {The dynamics of the modern Earth-system is not explicable
without reference to systems that have a purpose, i.e., that
exhibit goal-seeking behavior. This paper develops the
physical basis of agency or purposiveness in the
technosphere—the human-technological system that defines
the Anthropocene—as part of an analysis of the
organizational requirements of energy-dissipating systems.
The regulative, or framing, approach used here avoids
reliance on reductive modeling and aims instead at
establishing general properties of purposive systems.
Establishment of purposiveness (the condition of having a
purpose) as a physical system property, rather than a
metaphysical concept or a purely biological phenomenon,
enables a new look at the role of humans and human purpose
in the Anthropocene. This approach can help avoid the
misleading anthropocentric assumption that humans are
independent authors of the Anthropocene they inhabit, rather
than contingent actors whose purposes are not entirely their
own.},
Doi = {10.1016/j.ancene.2016.07.002},
Key = {fds323385}
}
@article{fds323386,
Author = {Williams, M and Zalasiewicz, J and Waters, CN and Edgeworth, M and Bennett, C and Barnosky, AD and Ellis, EC and Ellis, MA and Cearreta, A and Haff, PK and Ivar Do Sul and JA and Leinfelder, R and McNeill, JR and Odada, E and Oreskes, N and Revkin, A and Richter, DDB and Steffen, W and Summerhayes, C and Syvitski, JP and Vidas, D and Wagreich, M and Wing,
SL and Wolfe, AP and Zhisheng, A},
Title = {The Anthropocene: A conspicuous stratigraphical signal of
anthropogenic changes in production and consumption across
the biosphere},
Journal = {Earth'S Future},
Volume = {4},
Number = {3},
Pages = {34-53},
Publisher = {American Geophysical Union (AGU)},
Year = {2016},
Month = {March},
url = {http://dx.doi.org/10.1002/2015EF000339},
Abstract = {Biospheric relationships between production and consumption
of biomass have been resilient to changes in the Earth
system over billions of years. This relationship has
increased in its complexity, from localized ecosystems
predicated on anaerobic microbial production and consumption
to a global biosphere founded on primary production from
oxygenic photoautotrophs, through the evolution of Eukarya,
metazoans, and the complexly networked ecosystems of
microbes, animals, fungi, and plants that characterize the
Phanerozoic Eon (the last 541 million years of Earth
history). At present, one species, Homo sapiens, is
refashioning this relationship between consumption and
production in the biosphere with unknown consequences. This
has left a distinctive stratigraphy of the production and
consumption of biomass, of natural resources, and of
produced goods. This can be traced through stone tool
technologies and geochemical signals, later unfolding into a
diachronous signal of technofossils and human bioturbation
across the planet, leading to stratigraphically almost
isochronous signals developing by the mid-20th century.
These latter signals may provide an invaluable resource for
informing and constraining a formal Anthropocene
chronostratigraphy, but are perhaps yet more important as
tracers of a biosphere state that is characterized by a
geologically unprecedented pattern of global energy flow
that is now pervasively influenced and mediated by humans,
and which is necessary for maintaining the complexity of
modern human societies.},
Doi = {10.1002/2015EF000339},
Key = {fds323386}
}
@article{fds281143,
Author = {UNGAR, JE and HAFF, PK},
Title = {Steady state saltation in air},
Journal = {Sedimentology},
Volume = {34},
Number = {2},
Pages = {289-299},
Publisher = {WILEY},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1111/j.1365-3091.1987.tb00778.x},
Abstract = {Coupled equations of motion for steady state saltation over
an infinite plane are derived and solved for a simplified
model of the grain‐surface impact process. Experimentally
observed features of the wind velocity profile in saltation
are qualitatively reproduced, including a diminution of the
sub‐saltation layer mean wind speed, as the friction speed
increases. In this model the surface impact velocity of the
saltating grains remains relatively constant over a wide
range of free‐stream shear stresses, and the grain mass
flux increases with friction speed uf* less rapidly than
uf3. Copyright © 1987, Wiley Blackwell. All rights
reserved},
Doi = {10.1111/j.1365-3091.1987.tb00778.x},
Key = {fds281143}
}
@article{fds323387,
Author = {Williams, M and Zalasiewicz, J and Haff, PK and Schwägerl, C and Barnosky, AD and Ellis, EC},
Title = {The anthropocene biosphere},
Journal = {The Anthropocene Review},
Volume = {2},
Number = {3},
Pages = {196-219},
Publisher = {SAGE Publications},
Year = {2015},
Month = {December},
url = {http://dx.doi.org/10.1177/2053019615591020},
Abstract = {The geological record preserves evidence for two fundamental
stages in the evolution of Earth’s biosphere, a microbial
stage from ~3.5 to 0.65 Ga, and a metazoan stage evident by
c. 650 Ma. We suggest that the modern biosphere differs
significantly from these previous stages and shows early
signs of a new, third stage of biosphere evolution
characterised by: (1) global homogenisation of flora and
fauna; (2) a single species (Homo sapiens) commandeering
25-40% of net primary production and also mining fossil net
primary production (fossil fuels) to break through the
photosynthetic energy barrier; (3) human-directed evolution
of other species; and (4) increasing interaction of the
biosphere with the technosphere (the global emergent system
that includes humans, technological artefacts, and
associated social and technological networks). These unique
features of today’s biosphere may herald a new era in the
planet’s history that could persist over geological
timescales.},
Doi = {10.1177/2053019615591020},
Key = {fds323387}
}
@article{fds281126,
Author = {Zalasiewicz, J and Waters, CN and Williams, M and Barnosky, AD and Cearreta, A and Crutzen, P and Ellis, E and Ellis, MA and Fairchild, IJ and Grinevald, J and Haff, PK and Hajdas, I and Leinfelder, R and McNeill,
J and Odada, EO and Poirier, C and Richter, D and Steffen, W and Summerhayes, C and Syvitski, JPM and Vidas, D and Wagreich, M and Wing,
SL and Wolfe, AP and An, Z and Oreskes, N},
Title = {When did the Anthropocene begin? A mid-twentieth century
boundary level is stratigraphically optimal},
Journal = {Quaternary International},
Volume = {383},
Pages = {196-203},
Publisher = {Elsevier BV},
Year = {2015},
Month = {October},
ISSN = {1040-6182},
url = {http://dx.doi.org/10.1016/j.quaint.2014.11.045},
Abstract = {We evaluate the boundary of the Anthropocene geological time
interval as an epoch, since it is useful to have a
consistent temporal definition for this increasingly used
unit, whether the presently informal term is eventually
formalized or not. Of the three main levels suggested - an
'early Anthropocene' level some thousands of years ago; the
beginning of the Industrial Revolution at ~1800 CE (Common
Era); and the 'Great Acceleration' of the mid-twentieth
century - current evidence suggests that the last of these
has the most pronounced and globally synchronous signal. A
boundary at this time need not have a Global Boundary
Stratotype Section and Point (GSSP or 'golden spike') but
can be defined by a Global Standard Stratigraphic Age
(GSSA), i.e. a point in time of the human calendar. We
propose an appropriate boundary level here to be the time of
the world's first nuclear bomb explosion, on July 16th 1945
at Alamogordo, New Mexico; additional bombs were detonated
at the average rate of one every 9.6 days until 1988 with
attendant worldwide fallout easily identifiable in the
chemostratigraphic record. Hence, Anthropocene deposits
would be those that may include the globally distributed
primary artificial radionuclide signal, while also being
recognized using a wide range of other stratigraphic
criteria. This suggestion for the Holocene-Anthropocene
boundary may ultimately be superseded, as the Anthropocene
is only in its early phases, but it should remain practical
and effective for use by at least the current generation of
scientists.},
Doi = {10.1016/j.quaint.2014.11.045},
Key = {fds281126}
}
@article{fds323388,
Author = {Edgeworth, M and Richter, DDB and Waters, C and Haff, P and Neal, C and Price, SJ},
Title = {Diachronous beginnings of the anthropocene: The lower
bounding surface of anthropogenic deposits},
Journal = {The Anthropocene Review},
Volume = {2},
Number = {1},
Pages = {33-58},
Publisher = {SAGE Publications},
Year = {2015},
Month = {April},
url = {http://dx.doi.org/10.1177/2053019614565394},
Abstract = {Across a large proportion of Earth’s ice-free land
surfaces, a solid-phase stratigraphic boundary marks the
division between humanly modified ground and natural
geological deposits. At its clearest, the division takes the
form of an abrupt surface at the base of deposits variously
called ‘artificial ground’, ‘anthropogenic ground’
or ‘archaeological stratigraphy’ - which together
comprise a distinctive part of the geosphere called the
‘archaeosphere’. In other cases the bounding surface is
more diffuse, gradational or mixed, due to action of
non-human agencies and anthropedogenic forcings. It is
alternately conformable and unconformable. Layers above
typically contain artificial features, structures, artifacts
and other material traces of human activity, in contrast to
their relative absence in layers below. A fundamental
characteristic of the boundary is that it is diachronous,
still being formed and renewed today. In examining the
boundary, this paper asks - does it reflect the diachronous
onset and development of the Anthropocene
itself?.},
Doi = {10.1177/2053019614565394},
Key = {fds323388}
}
@article{fds323389,
Author = {Haff, P},
Title = {Humans and technology in the anthropocene: Six
rules},
Journal = {The Anthropocene Review},
Volume = {1},
Number = {2},
Pages = {126-136},
Publisher = {SAGE Publications},
Year = {2014},
Month = {August},
url = {http://dx.doi.org/10.1177/2053019614530575},
Abstract = {Humans play an essential role in creating the technological
systems of the Anthropocene, but, nonetheless, large-scale
technology - the ‘technosphere’ - operates according to
a quasiautonomous dynamics, summarized by six rules: (1) the
rule of inaccessibility, that large components of the
technosphere cannot directly influence the behavior of their
human parts; (2) the rule of impotence, that most humans
cannot significantly influence the behavior of large
technological systems; (3) the rule of control, that a human
cannot control a technological system that expresses a
larger number of behaviors than he himself; (4) the rule of
reciprocity, that a human can interact directly only with
systems his own size; (5) the rule of performance, that most
humans must perform at least some tasks that support the
metabolism of the technosphere; and (6) the rule of
provision, that the technosphere must provide an environment
for most humans conducive to their survival and
function.},
Doi = {10.1177/2053019614530575},
Key = {fds323389}
}
@article{fds323390,
Author = {Zalasiewicz, J and Williams, M and Waters, CN and Barnosky, AD and Haff,
P},
Title = {The technofossil record of humans},
Journal = {The Anthropocene Review},
Volume = {1},
Number = {1},
Pages = {34-43},
Publisher = {SAGE Publications},
Year = {2014},
Month = {April},
url = {http://dx.doi.org/10.1177/2053019613514953},
Abstract = {As humans have colonised and modified the Earth’s surface,
they have developed progressively more sophisticated tools
and technologies. These underpin a new kind of stratigraphy,
that we term technostratigraphy, marked by the geologically
accelerated evolution and diversification of technofossils -
the preservable material remains of the technosphere (Haff,
2013), driven by human purpose and transmitted cultural
memory, and with the dynamics of an emergent system. The
technosphere, present in some form for most of the
Quaternary, shows several thresholds. Its expansion and
transcontinental synchronisation in the mid 20th century has
produced a global technostratigraphy that combines very high
time-resolution, great geometrical complexity and wide
(including transplanetary) extent. Technostratigraphy can
help characterise the deposits of a potential Anthropocene
Epoch and its emergence marks a step change in planetary
mode.},
Doi = {10.1177/2053019613514953},
Key = {fds323390}
}
@article{fds281127,
Author = {Haff, PK},
Title = {Technology as a geological phenomenon: Implications for
human well-being},
Journal = {Geological Society, London, Special Publications},
Volume = {395},
Number = {1},
Pages = {301-309},
Booktitle = {A Stratigraphical Basis for the Anthropocene, Waters, C. N.,
et al, (Eds), Geological Society, London, Special
Publications SP 395-4},
Publisher = {Geological Society of London},
Year = {2014},
Month = {January},
ISSN = {0305-8719},
url = {http://dx.doi.org/10.1144/SP395.4},
Abstract = {The technosphere, the interlinked set of communication,
transportation, bureaucratic and other systems that act to
metabolize fossil fuels and other energy resources, is
considered to be an emerging global paradigm, with
similarities to the lithosphere, atmosphere, hydrosphere and
biosphere. The technosphere is of global extent, exhibits
large-scale appropriation of mass and energy resources,
shows a tendency to co-opt for its own use information
produced by the environment, and is autonomous. Unlike the
older paradigms, the technosphere has not yet evolved the
ability to recycle its own waste stream. Unless or until it
does so, its status as a paradigm remains provisional.
Humans are 'parts' of the technosphere-subcomponents
essential for system function. Viewed from the inside by its
human parts, the technosphere is perceived as a derived and
controlled construct. Viewed from outside as a geological
phenomenon, the technosphere appears as a quasi-autonomous
system whose dynamics constrains the behaviour of its human
parts. A geological perspective on technology suggests why
strategies to limit environmental damage that consider only
the needs of people are likely to fail without parallel
consideration of the requirements of technology, especially
its need for an abundant supply of energy. © The Geological
Society of London 2014.},
Doi = {10.1144/SP395.4},
Key = {fds281127}
}
@article{fds340276,
Author = {Haff, PK},
Title = {Biolevitation of pebbles on desert surfaces},
Journal = {Granular Matter},
Volume = {16},
Number = {2},
Pages = {275-278},
Year = {2014},
Month = {January},
url = {http://dx.doi.org/10.1007/s10035-013-0438-4},
Abstract = {Certain desert surfaces called desert pavements are
characterized by a nearly stone-free layer of fine granular
material, mostly silt (diameter of hundredths of mm) and
sand (tenths of mm) capped by a monolayer of pebble-sized
(few cm) stones. The fine granular material is deposited as
dust from the air, so the stones must be levitated to
accommodate emplacement of this material. In so-called
"normal grading" of stratigraphic deposits of geologic
material, as in many stream deposits, finer grained material
tends to settle on top of coarser grains which have faster
settling velocities. Anecdotal observations in the field
suggested that the observed "reverse grading" of pavement
surfaces is a consequence of the activity of small animals
that provide through their activities sufficient input of
energy to the surface to cause large particles to "float" on
the accumulating fine sediment. To test this idea a
laboratory experiment with a test organism, the large desert
beetle Eleodes, was carried out to observe possible sorting
process. Essentially random foraging motions of the beetles
in an environment in which fine sediment was periodically
added from above led to sorting of stones that were moveable
by the organisms, burial of immovable stones, as well as
burial and diffusion of marked grains that were comparable
in size to the fine sediment. These results help explain the
existence of a geologic deposit with an unusual layering of
grain sizes. © 2013 Springer-Verlag Berlin
Heidelberg.},
Doi = {10.1007/s10035-013-0438-4},
Key = {fds340276}
}
@article{fds281129,
Author = {Haff, PK},
Title = {Prediction in geology versus prediction in
engineering},
Journal = {Special Paper of the Geological Society of
America},
Volume = {502},
Pages = {127-134},
Booktitle = {Rethinking the Fabric of Geology, Baker, V.R., ed.,
Geological Society of America Special Papers
502},
Publisher = {Geological Society of America},
Year = {2013},
Month = {January},
ISSN = {0072-1077},
url = {http://dx.doi.org/10.1130/2013.2502(06)},
Abstract = {As humans become increasingly dominant agents of geologic
change, prediction of the reaction of natural systems to
human intervention and of the performance of geoengineered
structures assumes increasing importance. To help clarify
the role of geological prediction in an anthropic world, we
examine the end-member cases of prediction in natural
geologic systems and engineered systems. The behavior of
natural geologic systems tends to be less reliably
predictable than the behavior of engineered systems.
Engineered systems are designed, and their behavior is
predictable in terms of the function and interaction of
their parts. Geologic systems, although undesigned, also
have parts. Natural analogs of engineered parts are the
emergent structures arising from nonlinear interactions
between small-scale constituents. The behavior of natural
systems at a given scale follows directly from the dynamics
of their parts as defi ned at similar scales; it is argued
that application of same-scale dynamics, or scale matching,
provides the best basis for prediction in such systems.
Mathematical models of natural systems are also likely to be
most effective for prediction when applied at scales matched
to the scales of the phenomenon of interest. There are also
systems that are intermediate between natural systems and
engineered systems. A "peri-engineering" transition zone
governed by large-scale interactions is always present
between the parts of the engineered structure and the parts
of the surrounding natural environment. This contact region
between engineered structure and the natural environment is
often partially engineered to improve predictability. The
peri-engineering halo is only partly subject to human
design, and consequently it is often a region of reduced
predictability and increased probability of malfunction or
failure compared to the engineered system itself. © 2013
Geological Society of America.},
Doi = {10.1130/2013.2502(06)},
Key = {fds281129}
}
@article{fds281130,
Author = {Haff, PK},
Title = {Biolevitation of pebbles on desert surfaces},
Journal = {Granular Matter},
Volume = {16},
Number = {2},
Pages = {1-4},
Publisher = {Springer Nature},
Year = {2013},
ISSN = {1434-5021},
url = {http://dx.doi.org/10.1007/s10035-013-0438-4},
Abstract = {Certain desert surfaces called desert pavements are
characterized by a nearly stone-free layer of fine granular
material, mostly silt (diameter of hundredths of mm) and
sand (tenths of mm) capped by a monolayer of pebble-sized
(few cm) stones. The fine granular material is deposited as
dust from the air, so the stones must be levitated to
accommodate emplacement of this material. In so-called
"normal grading" of stratigraphic deposits of geologic
material, as in many stream deposits, finer grained material
tends to settle on top of coarser grains which have faster
settling velocities. Anecdotal observations in the field
suggested that the observed "reverse grading" of pavement
surfaces is a consequence of the activity of small animals
that provide through their activities sufficient input of
energy to the surface to cause large particles to "float" on
the accumulating fine sediment. To test this idea a
laboratory experiment with a test organism, the large desert
beetle Eleodes, was carried out to observe possible sorting
process. Essentially random foraging motions of the beetles
in an environment in which fine sediment was periodically
added from above led to sorting of stones that were moveable
by the organisms, burial of immovable stones, as well as
burial and diffusion of marked grains that were comparable
in size to the fine sediment. These results help explain the
existence of a geologic deposit with an unusual layering of
grain sizes. © 2013 Springer-Verlag Berlin
Heidelberg.},
Doi = {10.1007/s10035-013-0438-4},
Key = {fds281130}
}
@article{fds281160,
Author = {Haff, PK},
Title = {Technology and human purpose: The problem of solids
transport on the Earth's surface},
Journal = {Earth System Dynamics},
Volume = {3},
Number = {2},
Pages = {149-156},
Publisher = {Copernicus GmbH},
Year = {2012},
Month = {December},
ISSN = {2190-4979},
url = {http://dx.doi.org/10.5194/esd-3-149-2012},
Abstract = {Displacement of mass of limited deformability ("solids") on
the Earth's surface is opposed by friction and (the analog
of) form resistance - impediments relaxed by rotational
motion, self-powering of mass units, and transport
infrastructure. These features of solids transport first
evolved in the biosphere prior to the emergence of
technology, allowing slope-independent, diffusion-like
motion of discrete objects as massive as several tons, as
illustrated by animal foraging and movement along game
trails. However, highenergy-consumption technology powered
by fossil fuels required a mechanism that could support fast
advective transport of solids, i.e., long-distance,
high-volume, high-speed, unidirectional, slope-independent
transport across the land surface of materials like coal,
containerized fluids, minerals, and economic goods.
Pre-technology nature was able to sustain regional- and
global-scale advection only in the limited form of
piggybacking on geophysical flows of water (river sediment)
and air (dust). The appearance of a mechanism for sustained
advection of solids independent of fluid flows and gravity
appeared only upon the emergence of human purpose. Purpose
enables solids advection by, in effect, simulating a
continuous potential gradient, otherwise lacking, between
discrete and widely separated fossil-fuel energy sources and
sinks. Invoking purpose as a mechanism in solids advection
is an example of the need to import anthropic principles and
concepts into the language and methodology of modern Earth
system dynamics. As part of the emergence of a generalized
solids advection mechanism, several additional transport
requirements necessary to the function of modern large-scale
technological systems were also satisfied. These include
spatially accurate delivery of advected payload,
targetability to essentially arbitrarily located
destinations (such as cities), and independence of structure
of advected payload from transport mechanism. The latter
property enables the transport of an onboard power supply
and delivery of persistent-memory, high-information-content
payload, such as technological artifacts ("parts").
©Author(s)2012.},
Doi = {10.5194/esd-3-149-2012},
Key = {fds281160}
}
@article{fds281132,
Author = {Furbish, DJ and Haff, PK and Roseberry, JC and Schmeeckle,
MW},
Title = {A probabilistic description of the bed load sediment flux:
1. Theory},
Journal = {Journal of Geophysical Research: Earth Surface},
Volume = {117},
Number = {3},
Pages = {n/a-n/a},
Publisher = {American Geophysical Union (AGU)},
Year = {2012},
Month = {September},
ISSN = {0148-0227},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000309139300001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We provide a probabilistic definition of the bed load
sediment flux. In treating particle positions and motions as
stochastic quantities, a flux form of the Master equation (a
general expression of conservation) reveals that the
volumetric flux involves an advective part equal to the
product of an average particle velocity and the particle
activity (the solid volume of particles in motion per unit
streambed area), and a diffusive part involving the gradient
of the product of the particle activity and a diffusivity
that arises from the second moment of the probability
density function of particle displacements. Gradients in the
activity, instantaneous or time-averaged, therefore effect a
particle flux. Time-averaged descriptions of the flux
involve averaged products of the particle activity, the
particle velocity and the diffusivity; the significance of
these products depends on the scale of averaging. The flux
form of the Exner equation looks like a Fokker-Planck
equation (an advection-diffusion form of the Master
equation). The entrainment form of the Exner equation
similarly involves advective and diffusive terms, but
because it is based on the joint probability density
function of particle hop distances and associated travel
times, this form involves a time derivative term that
represents a lag effect associated with the exchange of
particles between the static and active states. The
formulation is consistent with experimental measurements and
simulations of particle motions reported in companion
papers. © 2012. American Geophysical Union. All Rights
Reserved.},
Doi = {10.1029/2012JF002352},
Key = {fds281132}
}
@article{fds281161,
Author = {Peter, H and Jackson, R},
Title = {A reply to Holl and Loik},
Journal = {Frontiers in Ecology and the Environment},
Volume = {9},
Number = {6},
Pages = {318-319},
Publisher = {WILEY},
Year = {2011},
Month = {August},
ISSN = {1540-9295},
url = {http://dx.doi.org/10.1890/11.WB.015},
Doi = {10.1890/11.WB.015},
Key = {fds281161}
}
@article{fds281159,
Author = {Jackson, R and Haff, P},
Title = {A "neoenvironmental" manifesto},
Journal = {Frontiers in Ecology and the Environment},
Volume = {9},
Number = {2},
Pages = {87},
Publisher = {WILEY},
Year = {2011},
Month = {March},
ISSN = {1540-9295},
url = {http://dx.doi.org/10.1890/1540-9295-9.2.87},
Doi = {10.1890/1540-9295-9.2.87},
Key = {fds281159}
}
@article{fds281162,
Author = {Haff, PK},
Title = {Hillslopes, rivers, plows, and trucks: Mass transport on
earth's surface by natural and technological
processes},
Journal = {Earth Surface Processes and Landforms},
Volume = {35},
Number = {10},
Pages = {1157-1166},
Publisher = {WILEY},
Year = {2010},
Month = {August},
ISSN = {0197-9337},
url = {http://dx.doi.org/DOI:10.1002/esp.1902},
Abstract = {The surface of the earth is being transformed by a new force
in the form of technological systems and processes that move
significant quantities of mass large distances. Because
movement of mass is perhaps the most basic geomorphic
process, and because the continuing rise of technology
appears to characterize a new epoch in earth evolution (the
Anthropocene), it is of interest to compare technological
and natural mass transport mechanisms. A purely dynamical
'mass-action' metric, representing the product of mass
displaced, distance moved, and mean speed of displacement,
is used to compare the transport effectiveness of selected
systems. Systems with large mass-action tend to be
advective, and systems with small mass-action diffusive.
Local environments are conditioned by mass-action through
the introduction of transport corridors, such as roads and
rivers, which put constraints on mass transport by embedded
diffusive systems. Advection also subjects local
environments to externally determined time scales, such as
the times for delivery of unit mass of water or sediment to
a river mouth, and supports the emergence of associated
dynamical processes there, for example those of human
activity or delta construction, that are too rapid to be
sustained by diffusion. Most of the world's mass-action is
generated by the motion of fluids of global or continental
extent, as in atmospheric circulation or river flow.
Technological mass-action exceeds that of all land-based
geomorphic systems except rivers. Technological systems with
large mass-action tend to be comprised of discrete,
self-powered units (e.g. trucks). Discretization of
transported mass reflects the different locomotion strategy
required for transport of solids on land, compared with the
transport requirements of spatially extensive fluids in
nature. The principle of maximum entropy production may
provide a framework for understanding the emergence of
advective, technological mass-transport systems. © 2010
John Wiley & Sons, Ltd.},
Doi = {10.1002/esp.1902},
Key = {fds281162}
}
@article{fds328733,
Author = {Furbish, DJ and Haff, PK},
Title = {From divots to swales: Hillslope sediment transport across
divers length scales},
Journal = {Journal of Geophysical Research},
Volume = {115},
Number = {F3},
Publisher = {American Geophysical Union (AGU)},
Year = {2010},
Month = {July},
url = {http://dx.doi.org/10.1029/2009jf001576},
Doi = {10.1029/2009jf001576},
Key = {fds328733}
}
@article{fds281158,
Author = {Ellis, EC and Haff, PK},
Title = {Earth science in the anthropocene: New Epoch, new Paradigm,
new responsibilities},
Journal = {Eos},
Volume = {90},
Number = {49},
Pages = {473},
Publisher = {American Geophysical Union (AGU)},
Year = {2009},
Month = {December},
ISSN = {0096-3941},
url = {http://dx.doi.org/10.1029/2009EO490006},
Doi = {10.1029/2009EO490006},
Key = {fds281158}
}
@article{fds281163,
Author = {Furbish, DJ and Haff, PK and Dietrich, WE and Heimsath,
AM},
Title = {Statistical description of slope-dependent soil transport
and the diffusion-like coefficient},
Journal = {Journal of Geophysical Research: Earth Surface},
Volume = {114},
Number = {4},
Publisher = {American Geophysical Union (AGU)},
Year = {2009},
Month = {September},
ISSN = {2169-9011},
url = {http://dx.doi.org/DOI:10.1029/2009JF001267},
Abstract = {[1] For hillslopes undergoing "diffusive" soil transport, it
is often assumed that the soil flux is proportional to the
local land-surface gradient, where the coefficient of
proportionality is like a diffusion coefficient. Inasmuch as
transport involves quasirandom soil particle motions related
to biomechanical mixing and similar dilational processes, a
slope-dependent relation arises from a balance between
particle fluxes that tend to loft a soil and gravitational
settling of particles into available pore space. A
specialized form of the Fokker-Planck equation adapted to
such particle motions clarifies how the particle flux
involves advective and diffusive parts. This in turn
contributes to a kinematic description of the diffusion-like
coefficient. Ingredients of this coefficient include an
active soil thickness, a characteristic particle size, the
porosity in excess of a consolidated porosity, and the rate
of particle activation as a function of depth. These last
two ingredients, vertical porosity structure and activation
rate, in effect characterize the magnitude and frequency of
settling particle motions related to biological activity and
thereby set the rate constant of the transport process. The
significance of land-surface slope is that it is a measure
of the downslope component of slope-normal lofting that is
balanced by settling. Because the diffusion-like coefficient
contains the soil thickness, the analysis suggests that the
soil flux is proportional to the "depth-slope" product. The
analysis is consistent with published profiles of soil creep
displacement and with published estimates of soil flux
obtained by downslope integration of soil production rates
for hillslopes in California and Australia. Copyright 2009
by the American Geophysical Union.},
Doi = {10.1029/2009JF001267},
Key = {fds281163}
}
@article{fds281128,
Author = {Haff, P},
Title = {Not a chance},
Journal = {Nature},
Volume = {459},
Number = {7246},
Pages = {606},
Publisher = {Springer Nature},
Year = {2009},
Month = {May},
ISSN = {0028-0836},
url = {http://dx.doi.org/DOI:10.1038/459606a},
Doi = {10.1038/459606a},
Key = {fds281128}
}
@article{fds281157,
Author = {Jon Furbish and D and Childs, EM and Haff, PK and Schmeeckle,
MW},
Title = {Rain splash of soil grains as a stochastic
advection-dispersion process, with implications for desert
plant-soil interactions and land-surface
evolution},
Journal = {Journal of Geophysical Research: Solid Earth},
Volume = {114},
Number = {3},
Publisher = {American Geophysical Union (AGU)},
Year = {2009},
Month = {March},
ISSN = {2169-9356},
url = {http://dx.doi.org/DOI:10.1029/2009JF001265},
Abstract = {We formulate soil grain transport by rain splash as a
stochastic advection-dispersion process. By taking into
account the intermittency of grain motions activated by
raindrop impacts, the formulation indicates that gradients
in raindrop intensity, and thus grain activity (the volume
of grains in motion per unit area) can be as important as
gradients in grain concentration and surface slope in
effecting transport. This idea is confirmed by rain splash
experiments and manifest in topographic roughening via mound
growth beneath desert shrubs. The formulation provides a
framework for describing transport and dispersal of any soil
material moveable by rain splash, including soil grains,
soil-borne pathogens and nutrients, seeds, or debitage. As
such, it shows how classic models of topographic "diffusion"
reflect effects of slope-dependent grain drift, not
diffusion, and it highlights the role of rain splash in the
ecological behavior of desert shrubs as "resource islands."
Specifically, the growth of mounds beneath shrub canopies,
where differential rain, splash initially causes more grains
to be splashed inward beneath the protective canopy than
outward, involves the "harvesting" of nearby soil material,
including nutrients. Mounds thus represent temporary storage
of soil derived from areas surrounding the shrubs. As the
inward grain flux associated with differential rain splash
is sustained over the shrub lifetime, mound material is
effectively sequestered from erosional processes that might
otherwise move this material downslope. With shrub death and
loss of the protective canopy, differential rain splash
vanishes and the mound material is dispersed to the
surrounding area, again subject to downslope movement.
Copyright 2009 by the American Geophysical
Union.},
Doi = {10.1029/2009JF001265},
Key = {fds281157}
}
@article{fds281156,
Author = {Murray, AB and Lazarus, E and Ashton, A and Baas, A and Coco, G and Coulthard, T and Fonstad, M and Haff, P and McNamara, D and Paola, C and Pelletier, J and Reinhardt, L},
Title = {Geomorphology, complexity, and the emerging science of the
Earth's surface},
Journal = {Geomorphology},
Volume = {103},
Number = {3},
Pages = {496-505},
Publisher = {Elsevier BV},
Year = {2009},
Month = {February},
ISSN = {0169-555X},
url = {http://dx.doi.org/DOI:10.1016/j.geomorph.2008.08.013},
Abstract = {The following is a white paper (adapted here for print) for
the U.S. National Research Council's committee on Challenges
and Opportunities in Earth Surface Processes, drafted at a
National Science Foundation sponsored workshop associated
with the 38th Binghamton Geomorphology Symposium,
"Complexity in Geomorphology," held at Duke University in
October 2007. © 2008 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.geomorph.2008.08.013},
Key = {fds281156}
}
@article{fds281154,
Author = {Haff, PK},
Title = {The landscape Reynolds number and other dimensionless
measures of Earth surface processes},
Journal = {Geomorphology},
Volume = {91},
Number = {3-4},
Pages = {178-185},
Publisher = {Elsevier BV},
Year = {2007},
Month = {November},
ISSN = {0169-555X},
url = {http://dx.doi.org/10.1016/j.geomorph.2007.04.010},
Abstract = {An analogy between turbulent fluid systems and landscape
drainage systems [Parker, G., Haff, P.K., Murray, A.B.,
2001, EOS, Transactions of the American Geophysical Union,
82, pp. F564.] is suggested by the observation that
transport in both systems can be approximated by diffusion
with size-proportional effective diffusivities, with a
cross-over at small scales to Fickian diffusion. The
"landscape" Reynolds number of a typical fluvial landscape
is estimated to be of order ReL ∼ 106 to 109, these large
values reflecting the relative efficiency of fluvial
transport compared to creep. ReL is the ratio of the
large-scale effective diffusivity of rivers to the
small-scale diffusivity of creep processes on hillslopes.
The spatial dependence of the effective diffusivity produces
rivers with logarithmic long-profiles, similar to the
profiles of many rivers in nature, and analogous to the
logarithmic dependence of mean fluid velocity on distance
from a wall in turbulent flow. The landscape example
suggests how other generalized "Reynolds numbers" can be
constructed as ratios of large-scale to small-scale
diffusivities to measure the efficiencies of complex
processes that affect the surface. As an example, the global
airline transportation network is estimated to have an
efficacy relative to that of direct human mechanisms for
transport of similar goods and materials of about 108 as
measured by a corresponding "technology" Reynolds number.
The appearance of such large dimensionless numbers,
pertaining to the consequences of human invention and
design, reflects the emergence of the technosphere as an
increasingly efficient overlay on the historical domain of
biology and surficial geology. © 2007 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.geomorph.2007.04.010},
Key = {fds281154}
}
@article{fds281155,
Author = {Chan, KMA and Pringle, RM and Ranganathan, J and Boggs, CL and Chan, YL and Ehrlich, PR and Haff, PK and Heller, NE and Al-Khafaji, K and Macmynowski, DP},
Title = {When agendas collide: human welfare and biological
conservation.},
Journal = {Conservation Biology : the Journal of the Society for
Conservation Biology},
Volume = {21},
Number = {1},
Pages = {59-68},
Year = {2007},
Month = {February},
ISSN = {0888-8892},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17298511},
Abstract = {Conservation should benefit ecosystems, nonhuman organisms,
and current and future human beings. Nevertheless, tension
among these goals engenders potential ethical conflicts:
conservationists' true motivations may differ from the
justifications they offer for their activities, and
conservation projects have the potential to disempower and
oppress people. We reviewed the promise and deficiencies of
integrating social, economic, and biological concerns into
conservation, focusing on research in ecosystem services and
efforts in community-based conservation. Despite much
progress, neither paradigm provides a silver bullet for
conservation's most pressing problems, and both require
additional thought and modification to become maximally
effective. We conclude that the following strategies are
needed to make conservation more effective in our
human-dominated world. (1) Conservation research needs to
integrate with social scholarship in a more sophisticated
manner. (2) Conservation must be informed by a detailed
understanding of the spatial, temporal, and social
distributions of costs and benefits of conservation efforts.
Strategies should reflect this understanding, particularly
by equitably distributing conservation's costs. (3) We must
better acknowledge the social concerns that accompany
biodiversity conservation; accordingly, sometimes we must
argue for conservation for biodiversity's sake, not for its
direct human benefits.},
Doi = {10.1111/j.1523-1739.2006.00570.x},
Key = {fds281155}
}
@article{064310191589,
Author = {Strudley, MW and Murray, AB and Haff, PK},
Title = {Emergence of pediments, tors, and piedmont junctions from a
bedrock weathering-regolith thickness feedback},
Journal = {Geology},
Volume = {34},
Number = {10},
Pages = {805-808},
Publisher = {Geological Society of America},
Year = {2006},
Month = {October},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/G22482.1},
Keywords = {Landforms;Sediment transport;Weathering;Erosion;Geomorphology;Lithology;},
Abstract = {Sediment erosion laws form the basis for most landscape
evolution models and guide geomorphologists in the pursuit
of understanding how landscapes evolve. This focus on the
alluvial surface, however, ignores the role of intrinsic
feedbacks between sediment transport and bedrock weathering
in shaping Earth's landforms. Here, we present a new,
parsimonious explanation for the origin and maintenance of
pediments, piedmont junctions, and tors, which emerge
spontaneously in a numerical model coupling bedrock
weathering and sediment transport. The spatial uniformity of
the thin regolith mantle that often characterizes pediments
is a manifestation of a negative feedback between bedrock
weathering and regolith thickness: if regolith thins
(thickens) by sediment transport, the regolith production
rate will increase (decrease), maintaining an equilibrium
regolith thickness on the piedmont. We propose that high
infiltration capacities and the instability of ephemeral
channel banks in and and semiarid environments suppress
fluvial incision and promote the smoothness of pediments. A
positive feedback between bedrock weathering and regolith
thickness causes tor growth: if regolith thins locally below
a critical value, regolith production slows while
surrounding areas continue to weather and erode more
rapidly. We suggest that many pedimented and tor-studded
landscapes may therefore be a consequence of intrinsic
sediment transport-weathering feedbacks mediated by climatic
and tectonic conditions, not by lithologic templates. ©
2006 Geological Society of America.},
Doi = {10.1130/G22482.1},
Key = {064310191589}
}
@article{fds281152,
Author = {Strudley, MW and Muray, AB and Haff, PK},
Title = {Regolith thickness instability and the formation of tors in
arid environments},
Journal = {Journal of Geophysical Research: Earth Surface},
Volume = {111},
Number = {3},
Pages = {n/a-n/a},
Publisher = {American Geophysical Union (AGU)},
Year = {2006},
Month = {September},
ISSN = {2169-9011},
url = {http://dx.doi.org/10.1029/2005JF000405},
Abstract = {We present model results suggesting that a physical
erosion-bedrock weathering feeback is responsible for the
development of isolated bedrock knobs (tors/inselbergs) that
often punctuate otherwise smooth pediments of homogeneous
basement lithology. Tors and larger, more heavily jointed
and morphologically complex exposures, inselbergs, may arise
as a consequence of fluctuations in rainfall and sediment
transport conditions combined with a bedrock weathering
mechanism that depends on regolith thickness.
Hydrogeochemical considerations and field observations in
arid, granitic environments suggest that the relationship
between weathering rate and regolith thickness exhibits a
maximum for a finite thickness of cover. We have
encapsulated this simple erosion-weathering feedback in a
numerical model simulating arid/ semiarid landscape
evolution that produces low-sloping pediments punctuated by
tors. Tors form during periods of higher effective moisture,
resulting in local base level incision and regolith thinning
on pediments, invoking a transition in which mantled
surfaces lower at rates exceeding the bare bedrock
weathering rate. This condition favors the emergence and
growth of tors in areas covered by regolith thickness less
than a threshold value. Subsequent shifts in climate or
local base level that restore sediment surface lowering
rates less than the bare bedrock weathering rate will lead
to a progressive decrease in tor height and, ultimately,
their disappearance. Thus, according to this model, tors in
and environments represent possibly transient features
related to fluctuations in climate or local transport
conditions rather than palimpsests of an ancient landscape
derived from differential subsurface weathering followed by
regolith stripping. Copyright 2006 by the Americal
Geophysical Union.},
Doi = {10.1029/2005JF000405},
Key = {fds281152}
}
@article{fds281153,
Author = {Haff, PK},
Title = {Response of desert pavement to seismic shaking, Hector Mine
earthquake, California, 1999},
Journal = {Journal of Geophysical Research: Earth Surface},
Volume = {110},
Number = {2},
Publisher = {American Geophysical Union (AGU)},
Year = {2005},
Month = {June},
ISSN = {2169-9011},
url = {http://dx.doi.org/10.1029/2003JF000054},
Abstract = {[1] The October 1999 M<inf>w</inf> 7.1 Hector Mine
earthquake in the Mojave Desert, California, generated
characteristic surface disturbances on nearby desert
pavements. These disturbances included (1) zones of
wholesale gravel displacement interspersed with zones of
intact pavement, (2) displaced and .rotated cobbles, (3)
moats around loosened, embedded boulders, (4) filling of
abandoned cobble sockets, boulder moats, and other
depressions with gravel, and (5) formation of narrow,
subparallel, linear strips of exposed fine-grained
subpavement matrix (matrix lineations). Clasts displaced
from matrix lineations and from cobble sockets tended to
move downslope. Sharp boundaries of matrix lineations and
slope-controlled displacement directions on slopes of only a
few degrees indicated that clasts remained close to the
pavement surface during shaking. The regular, few decimeter
spacing of matrix lineations suggests the presence of
standing waves during seismic shaking. Boulder moats
probably have good preservation potential and, at some
desert pavement locations, might provide information on
paleoseismic shaking. Although readily produced by coseismic
shaking, displaced cobbles are unreliable indicators of past
earthquake activity because of potential multiple origins.
For an assumed earthquake recurrence interval of 10 ka,
seismically driven sediment fluxes similar to those
generated by the Hector Mine earthquake at the Lavic Siding
pavement study site may be marginally competitive with
aseismic smoothing mechanisms driven by bioturbation,
rainbeat, and wash. For a 1 ka recurrence interval, seismic
smoothing is likely to play a significant role in pavement
evolution. Copyright 2005 by the American Geophysical
Union.},
Doi = {10.1029/2003JF000054},
Key = {fds281153}
}
@article{fds281151,
Author = {Haff, PK},
Title = {Neogeomorphology},
Journal = {Eos},
Volume = {83},
Number = {29},
Pages = {310-310},
Publisher = {American Geophysical Union (AGU)},
Year = {2002},
Month = {July},
ISSN = {0096-3941},
url = {http://dx.doi.org/10.1029/2002EO000223},
Doi = {10.1029/2002EO000223},
Key = {fds281151}
}
@article{fds281164,
Author = {Haff, PK},
Title = {Desert pavement: An environmental canary?},
Journal = {The Journal of Geology},
Volume = {109},
Number = {5},
Pages = {661-668},
Publisher = {University of Chicago Press},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1086/321960},
Abstract = {Ongoing disruption of ancient, varnished desert pavement
surfaces near Death Valley National Park is inferred to be
the result of unusually intense animal foraging activity.
Increased levels of bioturbation are associated with
enhanced vegetation growth stimulated by recent El Nino
precipitation. The occurrence of abundant, recently
overturned, varnished clasts suggests that the pavement
disturbances reported here are rare on the millennial time
scale of desert varnish formation. These observations
suggest the possibility that changes in desert pavement
surfaces may provide early hints of future changes in desert
ecology and environment.},
Doi = {10.1086/321960},
Key = {fds281164}
}
@article{fds281150,
Author = {Haff, PK},
Title = {Rivers, blood and transportation networks.},
Journal = {Nature},
Volume = {408},
Number = {6809},
Pages = {159-160},
Year = {2000},
Month = {November},
ISSN = {0028-0836},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11089962},
Doi = {10.1038/35041633},
Key = {fds281150}
}
@article{fds281131,
Author = {Jyotsna, R},
Title = {Microtopography as an indicator of modern hillslope
diffusivity in arid terrain},
Journal = {Geology},
Volume = {25},
Number = {8},
Pages = {695-698},
Publisher = {Geological Society of America},
Year = {1997},
Month = {January},
ISSN = {0091-7613},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1997XR32200006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {Diffusion of topography is normally considered a smoothing
process, but at the scale of the diffusive disturbance,
diffusion becomes a roughening process. Roughening is
exemplified by topographic features associated with
disturbances such as animal burrows, hoof prints of grazing
animals, and small landslides (here called large-scale
processes). Diffusive processes that make small or
indistinct topographic landmarks, such as rain splash and
rhcological creep (here called small-scale processes), tend
to erase these roughness elements. The ratio of the
small-scale diffusion coefficient to the large-scale
diffusion coefficient can be estimated by a measurement of
the areal density of large-scale disturbances. In lightly
vegetated, arid terrain, small-scale diffusion is dominant
unless large-scale roughness elements cover a large fraction
of the surface. The values of large-scale and small-scale
modern diffusion coefficients can be estimated if the rate
of generation of large-scale disturbances is known. Such
estimates are performed for a burrowed fault scarp in
Nevada.},
Doi = {10.1130/0091-7613(1997)025<0695:MAAIOM>2.3.CO;2},
Key = {fds281131}
}
@article{96063204446,
Author = {Raghuraman, J and Haff, PK},
Title = {Scaling-up of small-scale granular sediment transport
laws},
Journal = {Proceedings of Engineering Mechanics},
Volume = {1},
Pages = {262-264},
Address = {Fort Lauderdale, FL, USA},
Year = {1996},
Month = {January},
Keywords = {Granular materials;Mechanics;Computer simulation;Erosion;Runoff;Soils;Mathematical
models;Channel flow;Sediments;Shear stress;},
Abstract = {Practical applications of laboratory sediment transport
studies include the attempt to predict erosion of soil on
hillslopes subject to rainfall-induced runoff. Most
scientific studies of the mechanics of sediment transport
have been performed at laboratory-scale, or in limited
reaches of streams where bed and flow conditions are
relatively well-known. The study reported here examines the
application of basic sediment transport laws to prediction
of large-scale sediment fluxes on hillslopes where
topographic details of the slope are unknown at scales below
the cell-size of the simulation. In particular, the
situation in which small channels or rills on the hillslope
are not resolved is examined. It is shown that empirical
power-law sediment transport rules may generate systematic
errors in their prediction of erosion and deposition
rates.},
Key = {96063204446}
}
@article{96110389582,
Author = {Haff, PK and Werner, BT},
Title = {Dynamical Processes on Desert Pavements and the Healing of
Surficial Disturbances},
Journal = {Quaternary Research},
Volume = {45},
Number = {1},
Pages = {38-46},
Publisher = {Cambridge University Press (CUP)},
Year = {1996},
Month = {January},
ISSN = {0033-5894},
url = {http://dx.doi.org/10.1006/qres.1996.0004},
Abstract = {Mature desert pavements are traditionally regarded as
hallmarks of stability, but their stability is dynamic, not
static. In a study aimed at documenting this dynamic
stability and its role in healing surface disturbances,
experiments were performed over a 5-yr period on small
cleared patches, or plats, on pavement surfaces in Panamint
Valley, California. These experiments show that stones from
plat edges begin to resurface the clearing at rates of about
1% per year on 40-cm-square plats and 10% per year on
10-cm-square plats. Stones contributing to the regenerated
pavement have smaller average diameters than stones on the
surrounding pavement. Cavities 5-10 cm deep, formed in
mature pavement by removal of embedded boulders, fill by
ravel and slope failure. After five years, cavity depth has
been reduced by as much as 60%. Forty-year-old boulder
cavities are nearly completely refilled and have been
repaved by smaller than average pavement stones. Gaps caused
by removal of small stones (2-3 cm) have completely healed
in 5 yr. Displacement of surface stones by small animals is
a major component of the healing process. © 1996 University
of Washington.},
Doi = {10.1006/qres.1996.0004},
Key = {96110389582}
}
@article{194276,
Author = {Haff, PK and Eisenberg, JM},
Title = {Dynamic nuclear effects in pionic and kaonic
atoms},
Journal = {Phys. Lett. B (Netherlands)},
Volume = {33B},
Number = {2},
Pages = {133-136},
Year = {1996},
Keywords = {mesic and muonic atoms;},
Abstract = {Corrections have been calculated to adsorption widths in
pionic and kaonic atoms due to the admixture of excited
nuclear states. Effects as large as 12% and 27% are
indicated for pionic and kaonic atoms, respectively},
Key = {194276}
}
@article{95062731563,
Author = {Haff, PK},
Title = {Constitutive laws and prediction in granular
systems},
Journal = {Proceedings of Engineering Mechanics},
Volume = {2},
Pages = {786-789},
Address = {Boulder, CO, USA},
Year = {1995},
Month = {January},
Keywords = {Mathematical models;Composition effects;Large scale
systems;},
Abstract = {Constitutive properties of large-scale granular systems are
likely to be unique or ill-defined as the result of history
effects, compositional variation, and absence of suitable
averaging volumes. In consequence, fundamental physical
studies of granular systems at laboratory scale can
contribute in only a limited way to quantitative numerical
prediction of the behavior of large-scale granular
systems.},
Key = {95062731563}
}
@article{95062731599,
Author = {Haff, PK and Jiang, Z},
Title = {Vertical mixing of grains during bedload
transport},
Journal = {Proceedings of Engineering Mechanics},
Volume = {2},
Pages = {931-933},
Address = {Boulder, CO, USA},
Year = {1995},
Month = {January},
Keywords = {Mixing;Sediments;Traction (friction);Diffusion;Granular
materials;Mathematical models;},
Abstract = {Simulations of bedload transport predict that the active
layer of transported grains on a sediment bed is a zone of
vertical diffusion of sediment particles. Shallow exhumation
and burial of grains is possible in the absence of either
erosion or deposition. The thickness of the diffusion layer
is predicted to be proportional to the applied surface
traction.},
Key = {95062731599}
}
@article{fds281147,
Author = {Jiang, Z and Haff, PK},
Title = {Multiparticle simulation methods applied to the
micromechanics of bed load transport},
Journal = {Water Resources Research},
Year = {1993},
Month = {January},
Abstract = {We solve the Newtonian equations of motion to follow the
trajectories of each of a large number of two-dimensional
circular bed load particles as they move in response to
stresses exerted by an overlying fluid. The fluid is modeled
as a moving layer or 'slab' which exerts a
velocity-dependent drag force on embedded particles and
satisfies its own momentum balance equation. Bed load mass
flux and hop length and hop height statistics of simulated
beds resemble those observed in the laboratory. By marking
particles originally residing on the surface, vertical
mixing of sediment is investigated. An injection of fine
particles into a bed load system of coarse particles under
traction illustrates the early stages of the evolution of
sedimentary stratigraphy. Friction angles and their
distribution are investigated as a function of bed transport
history and particle size. The main thrust of the paper,
however, is to describe and test a microscopic bed load
model which engineers, geologists, and biologists may find
useful for applications where particle arrangement and
relative particle motion are important. (Authors)},
Key = {fds281147}
}
@article{fds281148,
Author = {Jiang, Z and Haff, PK},
Title = {Multiparticle simulation methods applied to the
micromechanics of bed load transport},
Journal = {Water Resources Research},
Volume = {29},
Number = {2},
Pages = {399-412},
Publisher = {American Geophysical Union (AGU)},
Year = {1993},
Month = {January},
url = {http://dx.doi.org/10.1029/92WR02063},
Abstract = {We solve the Newtonian equations of motion to follow the
trajectories of each of a large number of two‐dimensional
circular bed load particles as they move in response to
stresses exerted by an overlying fluid. The fluid is modeled
as a moving layer or “slab” which exerts a
velocity‐dependent drag force on embedded particles and
satisfies its own momentum balance equation. Bed load mass
flux and hop length and hop height statistics of simulated
beds resemble those observed in the laboratory. By marking
particles originally residing on the surface, vertical
mixing of sediment is investigated. An injection of fine
particles into a bed load system of coarse particles under
traction illustrates the early stages of the evolution of
sedimentary stratigraphy. Friction angles and their
distribution are investigated as a function of bed transport
history and particle size. The main thrust of the paper,
however, is to describe and test a microscopic bed load
model which engineers, geologists, and biologists may find
useful for applications where particle arrangement and
relative particle motion are important. Copyright 1993 by
the American Geophysical Union.},
Doi = {10.1029/92WR02063},
Key = {fds281148}
}
@article{fds281149,
Author = {HAFF, PK and ANDERSON, RS},
Title = {Grain scale simulations of loose sedimentary beds: the
example of grain‐bed impacts in aeolian
saltation},
Journal = {Sedimentology},
Volume = {40},
Number = {2},
Pages = {175-198},
Publisher = {WILEY},
Year = {1993},
Month = {January},
url = {http://dx.doi.org/10.1111/j.1365-3091.1993.tb01760.x},
Abstract = {Sediment transport by wind is one of many processes of
interest to the geomorphologist in which grain to grain
contacts play an important role. In order to illustrate the
modelling of collections of frictional, inelastic
sedimentary grains with the particle dynamics method (PDM),
we use the grain impact process in aeolian saltation as a
specific example. In PDM, all the forces on each particle
are evaluated at a sequence of small time‐steps, and the
Newtonian equations of motion are integrated forward in
time. Interparticle forces at grain contacts are treated as
springs with prescribed stiffness (normal force) and by a
Coulomb friction law (tangential force); particle
inelasticity is represented by spring damping. The granular
splash resulting from saltation impacts is assessed for
sensitivity to the choice of grain properties, and the
integration time‐step. We find that for the range of
impact speeds and impactor masses relevant to aeolian
settings, grain splashes are relatively insensitive to grain
stiffness, grain inelasticity and grain friction, and that
the pattern of ejection from the bed is largely controlled
by bed microtopography. A large set of impact realizations
involving a variety of impact points on a small set of
target beds is used to collect the appropriate statistics
for describing the stochastic splash process. The splash
function representing these statistics is then available for
use in calculations over longer time‐scales, such as the
evolution of the saltation curtain. The details given here
will enable the interested reader to adapt PDM modelling to
other types of clastic sedimentary systems. Copyright ©
1993, Wiley Blackwell. All rights reserved},
Doi = {10.1111/j.1365-3091.1993.tb01760.x},
Key = {fds281149}
}
@article{93091081163,
Author = {Haff, PK and Jiang, Z and Forrest, SB},
Title = {Transport of granules by wind and water: Micromechanics to
macromechanics in geology and engineering},
Journal = {Mechanics of Materials},
Volume = {16},
Number = {1-2},
Pages = {173-178},
Publisher = {Elsevier BV},
Address = {Potsdam, NY, USA},
Year = {1993},
Month = {January},
ISSN = {0167-6636},
url = {http://dx.doi.org/10.1016/0167-6636(93)90040-X},
Keywords = {Transport properties;Fluid mechanics;Flow of
fluids;Mixing;Water;Wind;Sand;Sediments;Shear
stress;Microstructure;Mathematical models;},
Abstract = {We present two examples of micromechanical simulations and
show how the calculations can be used to draw useful
conclusions at the macroscopic leve. In bedload transport by
water we examine the mixing depth of sediments undergoing
shear traction. In transport of dry sand grains by wind we
examine the development of periodic bedforms and the burial
and preservation of bedding surfaces. ©
1993.},
Doi = {10.1016/0167-6636(93)90040-X},
Key = {93091081163}
}
@article{fds328737,
Author = {HAFF, PK and FORREST, S},
Title = {WIND RIPPLES FORM AND STRATIGRAPHY},
Journal = {Geotimes},
Volume = {37},
Number = {7},
Pages = {12-14},
Publisher = {AMER GEOLOGICAL INST},
Year = {1992},
Month = {July},
Key = {fds328737}
}
@article{92041264888,
Author = {Forrest, SB and Haff, PK},
Title = {Mechanics of wind ripple stratigraphy.},
Journal = {Science (New York, N.Y.)},
Volume = {255},
Number = {5049},
Pages = {1240-1243},
Year = {1992},
Month = {March},
ISSN = {0036-8075},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17816833},
Abstract = {Stratigraphic patterns preserved under translating surface
undulations or ripples in a depositional eolian environment
are computed on a grain by grain basis using physically
based cellular automata models. The spontaneous appearance,
growth, and motion of the simulated ripples correspond in
many respects to the behavior of natural ripples. The
simulations show that climbing strata can be produced by
impact alone; direct action of fluid shear is unnecessary.
The model provides a means for evaluating the connection
between mechanical processes occurring in the
paleoenvironment during deposition and the resulting
stratigraphy preserved in the geologic column: vertical
compression of small laminae above a planar surface
indicates nascent ripple growth; supercritical laminae are
associated with unusually intense deposition episodes; and a
plane erosion surface separating sets of well-developed
laminae is consistent with continued migration of mature
ripples during a hiatus in deposition.},
Doi = {10.1126/science.255.5049.1240},
Key = {92041264888}
}
@article{92060512809,
Author = {Haff, PK},
Title = {Discrete mechanics of sediment transport},
Journal = {Proceedings of Engineering Mechanics},
Pages = {756-759},
Address = {College Station, TX, USA},
Year = {1992},
Month = {January},
Keywords = {Flow of Fluids - Granular Materials;Fluid
Mechanics;Mathematical Techniques - Differential
Equations;},
Abstract = {Usually a granular medium is being represented by a
continuous approximation in which the degrees of freedom of
individual grains are averaged away in favor of a partial
differential equation (PDE). To do this we need a
constitutive equation. This paper describes an impact
process which is slove sensitive, since unit surface
elements oriented into the wind receive more impact per unit
time than surface elements oriented downwind. Although the
systems simulated in the paper are small compared to the
expanse of a sand dune surface, the stratigraphic patterns
generated in each small sample are diagnostic of mechanical
conditions (wind velocity etc.) prevailing at deposition,
and therefore may serve as indicators of},
Key = {92060512809}
}
@article{fds327857,
Author = {Haff, PK and Jiang, Z and Forrest, SB},
Title = {Transport of Granules by Wind and Water: Micromechanics to
Macromechanics in Geology and Engineering},
Journal = {Studies in Applied Mechanics},
Volume = {31},
Number = {C},
Pages = {373-380},
Publisher = {Elsevier},
Year = {1992},
Month = {January},
url = {http://dx.doi.org/10.1016/B978-0-444-89213-3.50044-4},
Abstract = {We present two examples of micromechanical simulations and
show how the calculations can be used to draw useful
conclusions at the macroscopic level. In bedload transport
by water we examine the mixing-depth of sediments undergoing
shear-traction. In transport of dry sand grains by wind we
examine the development of periodic bedforms and the burial
and preservation of bedding surfaces. © 1992, Elsevier
B.V.},
Doi = {10.1016/B978-0-444-89213-3.50044-4},
Key = {fds327857}
}
@article{fds328736,
Author = {HAFF, PK},
Title = {WIND RIPPLES AS TIMES MEMORY},
Journal = {Recherche},
Volume = {23},
Number = {247},
Pages = {1186-1188},
Year = {1992},
Key = {fds328736}
}
@article{91110333088,
Author = {Haff, PK},
Title = {Basic physical models in sediment transport},
Journal = {Coastal Sediments '91},
Pages = {1-14},
Address = {Seattle, WA, USA},
Year = {1991},
Month = {January},
Keywords = {Flow of Fluids--Sediment Transport;Coastal Zones;Flow of
Solids--Granular Materials;Soils--Sediments;Sedimentation--Models;},
Abstract = {Basic particle dynamics and cellular automata micromodels of
clastic sediments are described and applications are
illustrated in the areas of aeolian saltation, bedload
transport, size segregation in shear flows, dry granular
flows and aeolian bedform generation.},
Key = {91110333088}
}
@article{4026704,
Author = {Gutt, GM and Haff, PK},
Title = {Boundary conditions on continuum theories of granular
flow},
Journal = {International Journal of Multiphase Flow},
Volume = {17},
Number = {5},
Pages = {621-634},
Publisher = {Elsevier BV},
Year = {1991},
Month = {January},
ISSN = {0301-9322},
url = {http://dx.doi.org/10.1016/0301-9322(91)90028-2},
Keywords = {Couette flow;granular materials;kinetic theory of
gases;two-phase flow;},
Abstract = {Continuum theories of highly agitated granular flows have
recently been developed based on ideas from the kinetic
theory of gases, with the fluctuation velocity of the grains
corresponding to the temperature of the gas. Most often the
boundary conditions for a granular system at a wall have
been taken to be the same as the boundary conditions for a
gas (i.e. the "no-slip" boundary conditions on the average
flow velocity and the temperature). However, it is clear
from experimental observations that a significant slip can
exist in the average flow velocity and temperature at a
wall. In this paper, a model of boundary conditions on
granular flows will be presented which incorporates the
following points: 1. 1. The average flow velocity of the
grains at the wall does not equal the wall velocity, with
the shear stress at the wall being proportional to the
difference in these velocities (the "slip velocity"). 2. 2.
Small-amplitude vibrations of the wall can be regarded as
one factor in an effective wall "temperature". The other
factor is the effect of the roughness of the wall coupled
with the slip velocity. The flux of "thermal" energy between
the granular system and the wall is determined by the
relative values of this effective wall "temperature" and the
granular system "temperature". 3. 3. Due to differences
between grain-grain and grain-wall collisions, the density
of the granular system may exhibit a "jump" at the wall. 4.
4. For walls of insufficient roughness, measured angles of
effective internal friction may reflect more the effect of
shearing at the wall than in the bulk. These boundary
conditions are illustrated by solving a problem in Couette
flow. © 1991.},
Doi = {10.1016/0301-9322(91)90028-2},
Key = {4026704}
}
@article{3275657,
Author = {Anderson, RS and Haff, PK},
Title = {Simulation of eolian saltation.},
Journal = {Science (New York, N.Y.)},
Volume = {241},
Number = {4867},
Pages = {820-823},
Year = {1988},
Month = {August},
ISSN = {0036-8075},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17829176},
Keywords = {atmospheric boundary layer;dust;sand;wind;},
Abstract = {Saltation is important in the transport of sand-sized
granular material by wind and in the ejection of dust from
the bed both on Earth and on Mars. The evolution of the
saltating population and all its characteristic profiles is
calculated from inception by pure aerodynamic entrainment
through to steady state. Results of numerical simulations of
single-grain impacts into granular beds are condensed into
analytic expressions for the number and speeds of grains
rebounding or rejected (splashed) from the bed. A model is
combined with (i) this numerical representation, (ii) an
expression for the aerodynamic entrainment rate, and (iii)
the modification of the wind velocity profile by saltating
grains. Calculated steady state mass fluxes are within the
range of mass fluxes measured in wind tunnel experiments;
mass flux is nonlinearly dependent on the shear velocity.
Aerodynamically entrained grains in the system are primarily
seeding agents; at steady state, aerodynamic entrainment is
rare. The time for the entire system to reach steady state
is roughly 1 second, or several long-trajectory hop
times.},
Doi = {10.1126/science.241.4867.820},
Key = {3275657}
}
@article{fds281144,
Author = {WERNER, BT and HAFF, PK},
Title = {The impact process in aeolian saltation: two‐dimensional
simulations},
Journal = {Sedimentology},
Volume = {35},
Number = {2},
Pages = {189-196},
Publisher = {WILEY},
Year = {1988},
Month = {January},
url = {http://dx.doi.org/10.1111/j.1365-3091.1988.tb00944.x},
Abstract = {ABSTRACT A critical event in the trajectory of a sand grain
saltating in air is its interaction with the surface. We
examine the phenomenon of grain‐bed impacts in two
dimensions using a combination of dynamical computer
simulations, analytical models and physical reasoning. The
results indicate that the grain‐bed collisions can be
treated as two‐body collisions with the bed particle
assuming an effective mass greater than its true mass. Also,
the presence of geometrical surface irregularities has a
strong bearing on the interaction between saltating and
surface grain populations, as well as on the formation of
small‐scale bedforms. Copyright © 1988, Wiley Blackwell.
All rights reserved},
Doi = {10.1111/j.1365-3091.1988.tb00944.x},
Key = {fds281144}
}
@article{3819590,
Author = {Werner, B.T. and Haff, P.K.},
Title = {Dynamical simulations of granular materials using the
Caltech Hypercube},
Journal = {Third Conference on Hypercube Concurrent Computers and
Applications},
Pages = {1313 - 18},
Address = {Pasadena, CA, USA},
Year = {1988},
Keywords = {digital simulation;granular materials;hypercube
networks;mechanical engineering computing;physics
computing;},
Abstract = {A technique for simulating the motion of granular materials
using the Caltech Hypercube is described. The authors
demonstrate that grain dynamics simulations run efficiently
on the Hypercube and therefore that they offer an
opportunity for greatly expanding the use of parallel
simulations in studying granular materials. Several
examples, which illustrate how the simulations can be used
to extract information concerning the behavior of granular
materials, are discussed},
Key = {3819590}
}
@article{88020028942,
Author = {Haff, PK and Werner, BT},
Title = {COLLISIONAL INTERACTION OF A SMALL NUMBER OF CONFINED,
INELASTIC GRAINS.},
Volume = {3},
Pages = {483-501},
Address = {Miami Beach, FL, USA},
Year = {1987},
Month = {December},
Keywords = {SOLIDS - Velocity Measurement;FLOW OF FLUIDS - Granular
Materials;},
Abstract = {In some grain systems of practical interest, however, the
dispersed grains, although playing an important role in the
system dynamics, are not numerous enough to justify a
continuum description a priori. We have studied a computer
model of one such system, in which a small number of
inelastic spheres driven by a localized energy source are
confined to an enclosed three dimensional space. Grain
inelasticity exerts a dominant influence on these systems.
With respect to the Maxwellian velocity distribution which
elastic particles with the same average 'temperature' would
show, the simulated velocity distribution exhibits a peak at
lower energy, with a significant high energy
tail.},
Key = {88020028942}
}
@article{87060093996,
Author = {Mitha, S and Tran, MQ and Werner, BT and Haff, PK},
Title = {The grain-bed impact process in aeolian saltation},
Journal = {Acta Mechanica},
Volume = {63},
Number = {1-4},
Pages = {267-278},
Publisher = {Springer Nature},
Address = {Interlaken, Switz},
Year = {1986},
Month = {November},
ISSN = {0001-5970},
url = {http://dx.doi.org/10.1007/BF01182553},
Keywords = {SAND AND GRAVEL;MATERIALS TESTING - Impact;WIND
EFFECTS;},
Abstract = {We report the results of impact experiments in which high
velocity steel spheres (BBs) were directed against a loose
bed of similar particles. The purpose of these experiments
is to shed some light on the collision processes which occur
when saltating sand grains driven by the wind strike the
bed. The scattered particles fall into two categories: a
single high energy rebound which scatters quasi-specularly,
and a number of low energy recoils. The high energy rebound
is identified with the "successive saltation" particle of
Rumpel, and the low energy recoils are interpreted as
creeping, or reptating particles. These observations provide
information on the "splash function" of Ungar and Haff,
which describes the response of a bed to grain impact and
which plays a central role in the theory of saltation. ©
1986 Springer-Verlag.},
Doi = {10.1007/BF01182553},
Key = {87060093996}
}
@article{2681610,
Author = {Shapiro, MH and Lo, DY and Haff, PK and Tombrello,
TA},
Title = {Simulation of sputtering from liquid Cu targets},
Journal = {Nuclear Instruments and Methods in Physics Research Section
B: Beam Interactions With Materials and Atoms},
Volume = {13},
Number = {1-3},
Pages = {348-352},
Publisher = {Elsevier BV},
Address = {Washington, DC, USA},
Year = {1986},
Month = {March},
ISSN = {0168-583X},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1986A702600066&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {copper;liquid metals;molecular dynamics method;sputtering;},
Abstract = {The sputtering of Cu atoms from liquid targets by normally
incident 5 keV Ar+ ions was simulated using the multiple
interaction molecular dynamics technique. Yields, energy
distributions, and angular distributions of sputtered atoms
were obtained at several temperatures slightly above and
below the experimental melting point of copper. In all cases
the resulting angular distributions of ejected atoms peaked
more sharply than the cos θ behavior predicted by linear
cascade theory. The ratio of yields from individual layers
of the liquid targets, and the energy and angular
distributions of ejected atoms generally were found to be
similar to those obtained in previous simulations with solid
Cu targets. Our results also are in qualitative agreement
with Dumke's measurements of angular distributions and layer
yield ratios of sputtered atoms from liquid Ga-In eutectic
alloy targets. In particular, no marked changes in yields or
energy distributions were observed when the temperature of
the target was lowered below the nominal melting point of
copper. The angular distributions were found to broaden with
increasing temperature. © 1986.},
Doi = {10.1016/0168-583X(86)90525-2},
Key = {2681610}
}
@article{88020024200,
Author = {Haff, PK},
Title = {A Physical Picture of Kinetic Granular Fluids},
Journal = {Journal of Rheology},
Volume = {30},
Number = {5},
Pages = {931-948},
Publisher = {Society of Rheology},
Address = {Blacksburg, VA, USA},
Year = {1986},
Month = {January},
url = {http://dx.doi.org/10.1122/1.549875},
Keywords = {KINETICS - Mathematical Models;},
Abstract = {We give a physical and heuristic discussion of the kinetic
model of granular fluids, wherein the grain plays the role
of a molecule. A consideration of the details of
grain—grain and grain—wall interactions leads naturally
to the equations of motion and to suitable boundary
conditions. Examples from a Couette flow geometry are used
to support the argument that the energy and momentum
equations must be treated on an equal footing. The
introduction of the energy equation leads to the appearance
of a new length scale A, the conduction length, which
describes the competition between viscous heating and
collisional energy absorption and whose value determines the
distribution of “granular temperature” and hence the
flow field in the fluid. © 1986, The Society of Rheology.
All rights reserved.},
Doi = {10.1122/1.549875},
Key = {88020024200}
}
@article{87030040511,
Author = {Haff, PK and Werner, BT},
Title = {Computer simulation of the mechanical sorting of
grains},
Journal = {Powder Technology},
Volume = {48},
Number = {3},
Pages = {239-245},
Publisher = {Elsevier BV},
Year = {1986},
Month = {January},
ISSN = {0032-5910},
url = {http://dx.doi.org/10.1016/0032-5910(86)80048-1},
Keywords = {CLASSIFIERS - Computer Simulation;GRANULAR MATERIALS -
Friction;FLOW OF FLUIDS - Granular Materials;},
Abstract = {A two-dimensional system of inelastic frictional disks all
of equal diameter save one was studied by computer
simulation. A single large disk was placed on the bottom of
a container and covered by 30 smaller disks. When the
container was agitated to induce a shear motion in the disk
assembly, the large particle showed a tendency to rise
toward the surface. This sorting process was mediated by
shear-driven rotational motion, the large grain rolling up
on top of neighboring small grains. The grain-grain friction
coefficient μ is a critical parameter in this kind of
sorting process, since if μ is too small, the large grain
cannot get sufficient purchase to roll without slipping. ©
1986.},
Doi = {10.1016/0032-5910(86)80048-1},
Key = {87030040511}
}
@article{86060026161,
Author = {Hui, K and Haff, PK},
Title = {Kinetic grain flow in a vertical channel},
Journal = {International Journal of Multiphase Flow},
Volume = {12},
Number = {2},
Pages = {289-298},
Publisher = {Elsevier BV},
Year = {1986},
Month = {January},
ISSN = {0301-9322},
url = {http://dx.doi.org/10.1016/0301-9322(86)90031-5},
Keywords = {FLUID DYNAMICS;MATHEMATICAL MODELS;},
Abstract = {A self-consistent kinetic grain flow model proposed earlier
has been applied in detail to the description of rapid flow
in a verticad channel. The equations of motion reduce to an
ordinary differential equation for the fluctuation velocity
ν, which is solved numerically. Boundary conditions on ν
are derived which incorporate the nature of grain-wall
collisions. The overall flow pattern is found to depend
significantly upon the grain inelasticity parameter γ (γ =
0 for elastic grains) and upon the grain diameter d. The
flow velocity profile is rounded for very elastic grains and
for large grains, but becomes more blunt as grain diameter
decreases or γ increases. For large enough γ, a region of
plug flow develops in the central region of the channel,
corresponding to a vanishing grain fluctuation velocity. In
this case the region of dispersed or "thermalized" grains,
within which all shearing occurs, is restricted to a thin
layer near each wall. © 1986.},
Doi = {10.1016/0301-9322(86)90031-5},
Key = {86060026161}
}
@article{2754696,
Author = {Haff, PK and Eviatar, A},
Title = {Micrometeoroid impact on planetary satellites as a
magnetospheric mass source},
Journal = {Icarus},
Volume = {66},
Number = {2},
Pages = {258-269},
Publisher = {Elsevier BV},
Year = {1986},
Month = {January},
ISSN = {0019-1035},
url = {http://dx.doi.org/10.1016/0019-1035(86)90156-9},
Keywords = {meteoroids;micrometeorites;planetary atmospheres;planetary
satellites;planets;},
Abstract = {Planetary satellites are an important source of mass for
planetary magnetospheres. Meteoroid impact vaporization is a
supply mechanism which can potentially compete with
charged-particle sputtering. Recent estimates of impact
fluxes in the outer solar system vary by several orders of
magnitude. For the larger flux values impact vaporization
will play a role both at Jupiter and Saturn, although for
the most part it will not dominate sputtering. At the small
end of the flux range, sputtering dominates magnetospheric
mass-loading everywhere. © 1986.},
Doi = {10.1016/0019-1035(86)90156-9},
Key = {2754696}
}
@article{fds281142,
Author = {Werner, BT and Haff, PK and Livi, RP and Anderson,
RS},
Title = {Measurement of eolian sand ripple cross-sectional
shapes.},
Journal = {Geology},
Volume = {14},
Number = {9},
Pages = {743-745},
Publisher = {Geological Society of America},
Year = {1986},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/0091-7613(1986)14<743:MOESRC>2.0.CO},
Abstract = {Measures shapes by casting a shadow perpendicular to the
ripple crests.-from Authors},
Doi = {10.1130/0091-7613(1986)14<743:MOESRC>2.0.CO},
Key = {fds281142}
}
@article{fds319907,
Author = {Shapiro, MH and Lo, DY and Haff, PK and Tombrello,
TA},
Title = {Simulation of sputtering from liquid Cu targets},
Journal = {Nuclear Instruments and Methods in Physics Research Section
B: Beam Interactions With Materials and Atoms},
Volume = {13},
Number = {1-3},
Pages = {348-352},
Year = {1986},
Abstract = {The sputtering of Cu atoms from liquid targets by normally
incident 5 keV Ar+ ions was simulated using the multiple
interaction molecular dynamics technique. Yields, energy
distributions, and angular distributions of sputtered atoms
were obtained at several temperatures slightly above and
below the experimental melting point of copper. In all cases
the resulting angular distributions of ejected atoms peaked
more sharply than the cos θ behavior predicted by linear
cascade theory. The ratio of yields from individual layers
of the liquid targets, and the energy and angular
distributions of ejected atoms generally were found to be
similar to those obtained in previous simulations with solid
Cu targets. Our results also are in qualitative agreement
with Dumke's measurements of angular distributions and layer
yield ratios of sputtered atoms from liquid Ga-In eutectic
alloy targets. In particular, no marked changes in yields or
energy distributions were observed when the temperature of
the target was lowered below the nominal melting point of
copper. The angular distributions were found to broaden with
increasing temperature. © 1986.},
Key = {fds319907}
}
@article{fds328738,
Author = {HAFF, PK},
Title = {BOOMING DUNES},
Journal = {American Scientist},
Volume = {74},
Number = {4},
Pages = {376-381},
Year = {1986},
Key = {fds328738}
}
@article{2543525,
Author = {Shapiro, MH and Haff, PK and Tombrello, TA and Harrison,
DE},
Title = {Simulation of isotopic mass effects in sputtering},
Journal = {Nuclear Instruments and Methods in Physics Research Section
B: Beam Interactions With Materials and Atoms},
Volume = {12},
Number = {1},
Pages = {137-145},
Publisher = {Elsevier BV},
Year = {1985},
Month = {January},
ISSN = {0168-583X},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1985APU1900017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {copper;digital simulation;isotope effects;molecular dynamics
method;sputtering;},
Abstract = {The multiple interaction, molecular dynamics code SPUT1 has
been used to simulate the effects of isotopic mass
differences on atoms sputtered from single crystal Cu
targets by normally incident Ar ions. Calculations were
carried out for 1 keV and 5 keV ions incident on natural Cu
targets (69.1% 63Cu, 30.9% 65Cu). and for 5 keV ions
incident on pseudo-Cu targets composed of mixtures of
natural Cu (63.546 amu) and "very light" Cu (50.837 amu) in
the abundance ratios 1:3, 1:1, and 3:1. In all cases the
sputtered ejecta showed an overall enrichment in the light
isotope relative to the isotopic composition of the target.
Preferential enrichment of the light isotope in the normal
direction was pronounced. Material ejected at oblique angles
was either depleted in the light isotope or had a much lower
enrichment of the light isotope compared to material ejected
normal to the target. Studies with the pseudo-Cu targets
showed that smaller enrichments were obtained when the
incident ion recoiled immediately back through the first
layer of the target, while larger enrichments were
associated with deeper penetration of the incident ion into
the target crystallite. In both cases, the average energy of
the light atoms in the collision cascade was found to be
higher than that of the heavy atoms. However, this effect
was enhanced with deeper penetration of the incident ion
into the target. The preferential enrichment of the light
ejected atoms normal to the target is largely the result of
a strong momentum asymmetry in the collision cascades. Light
atoms in the cascades, on average, carry far greater
momentum towards the surface of the target than do the heavy
atoms. A limited number of simulation runs also were carried
out with heavy ions (74 amu) incident on pseudo-Cu targets.
Overall enrichment of the light atoms in the sputtered
material was reduced, but the angular variation of the
isotopic yields persisted. © 1985.},
Doi = {10.1016/0168-583X(85)90709-8},
Key = {2543525}
}
@article{2563514,
Author = {Shapiro, MH and Haff, PK and Tombrello, TA and Jr, HDE and Webb,
RP},
Title = {Computer-simulated energy and angular distributions of
sputtered Cu atoms},
Journal = {Radiat. Eff. (Uk)},
Volume = {89},
Number = {3-4},
Pages = {234-255},
Year = {1985},
Keywords = {copper;molecular dynamics method;sputtering;},
Abstract = {The energy and angular distributions of copper atoms ejected
by 5 keV incident Ar ions have been simulated using the
multiple interaction molecular dynamics technique.
Calculations carried out with two independently written
computer codes yielded essentially identical results. As in
previous simulation studies of low to medium energy
sputtering, virtually all ejected atoms came from the first
layer or second layer. Two different ion-atom potentials
were used in the simulations. Absolute sputtering yields
depended strongly on the choice of potential; relative
yields and angular distributions were found to be
insensitive to the choice of potential. For Ar ions normally
incident on the (100), (110), and (111) faces of a FCC Cu
crystallite, ejected atoms from the second layer of the
crystallite exited preferentially in the forward direction
compared to those sputtered from the first layer. The energy
spectra of atoms ejected from the second layers were harder
than those of the first layer atoms},
Key = {2563514}
}
@article{fds319908,
Author = {Shapiro, MH and Haff, PK and Tombrello, TA and Jr,
DEH},
Title = {Simulation of isotopic mass effects in sputtering},
Journal = {Nuclear Instruments and Methods in Physics Research Section
B: Beam Interactions With Materials and Atoms},
Volume = {12},
Number = {1},
Pages = {137-145},
Year = {1985},
Abstract = {The multiple interaction, molecular dynamics code SPUT1 has
been used to simulate the effects of isotopic mass
differences on atoms sputtered from single crystal Cu
targets by normally incident Ar ions. Calculations were
carried out for 1 keV and 5 keV ions incident on natural Cu
targets (69.1% 63Cu, 30.9% 65Cu). and for 5 keV ions
incident on pseudo-Cu targets composed of mixtures of
natural Cu (63.546 amu) and "very light" Cu (50.837 amu) in
the abundance ratios 1:3, 1:1, and 3:1. In all cases the
sputtered ejecta showed an overall enrichment in the light
isotope relative to the isotopic composition of the target.
Preferential enrichment of the light isotope in the normal
direction was pronounced. Material ejected at oblique angles
was either depleted in the light isotope or had a much lower
enrichment of the light isotope compared to material ejected
normal to the target. Studies with the pseudo-Cu targets
showed that smaller enrichments were obtained when the
incident ion recoiled immediately back through the first
layer of the target, while larger enrichments were
associated with deeper penetration of the incident ion into
the target crystallite. In both cases, the average energy of
the light atoms in the collision cascade was found to be
higher than that of the heavy atoms. However, this effect
was enhanced with deeper penetration of the incident ion
into the target. The preferential enrichment of the light
ejected atoms normal to the target is largely the result of
a strong momentum asymmetry in the collision cascades. Light
atoms in the cascades, on average, carry far greater
momentum towards the surface of the target than do the heavy
atoms. A limited number of simulation runs also were carried
out with heavy ions (74 amu) incident on pseudo-Cu targets.
Overall enrichment of the light atoms in the sputtered
material was reduced, but the angular variation of the
isotopic yields persisted. © 1985.},
Key = {fds319908}
}
@article{2346371,
Author = {Hui, K and Haff, PK and Ungar, JE},
Title = {Boundary conditions for high-shear grain
flows},
Journal = {Journal of Fluid Mechanics},
Volume = {145},
Number = {EM1},
Pages = {223-233},
Publisher = {Cambridge University Press (CUP)},
Year = {1984},
Month = {January},
url = {http://dx.doi.org/10.1017/S0022112084002883},
Keywords = {boundary-value problems;Couette flow;fluctuations;shear
flow;two-phase flow;},
Abstract = {Boundary conditions are developed for rapid granular flows
in which the rheology is dominated by grain–grain
collisions. These conditions are [formula-omitted] and u0 =
const du0/dy, where [formula-omitted] and u are the thermal
(fluctuation) and flow velocities respectively, and the
subscript indicates that these quantities and their
derivatives are to be evaluated at the wall These boundary
conditions are derived from the nature of individual
grain–wall collisions, so that the proportionality
constants involve the appropriate coefficient of restitution
ew for the thermal velocity equation, and the fraction of
diffuse (i.e. non-specular) collisions in the case of the
flow-velocity equation. Direct application of these boundary
conditions to the problem of Couette-flow shows that as long
as the channel width h is very large compared with a grain
diameter d it is permissible to set [formula-omitted] at the
wall and to adopt the no-slip condition. Exceptions occur
where d/h is not very small, when the wall is not rough, and
when the grain–wall collisions are very elastic. Similar
insight into other flows can be obtained qualitatively by a
dimensional analysis treatment of the boundary conditions.
Finally, the more difficult problem of self-bounding fluids
is discussed qualitatively. © 1984, Cambridge University
Press. All rights reserved.},
Doi = {10.1017/S0022112084002883},
Key = {2346371}
}
@article{fds328739,
Author = {HAFF, PK},
Title = {SPUTTERING BY PARTICLE BOMBARDMENT, PT 2, SPUTTERING OF
ALLOYS AND COMPOUNDS, ELECTRON AND NEUTRON SPUTTERING,
SURFACE-TOPOGRAPHY - BEHRISCH,R},
Journal = {American Scientist},
Volume = {72},
Number = {5},
Pages = {510-510},
Year = {1984},
Key = {fds328739}
}
@article{2136743,
Author = {Summers, ME and Yung, YL and Haff, PK},
Title = {A two-stage mechanism for escape of Na and K from
Io},
Journal = {Nature},
Volume = {304},
Number = {5928},
Pages = {710-712},
Publisher = {Springer Nature},
Year = {1983},
Month = {December},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/304710a0},
Keywords = {Jupiter;planetary atmospheres;planetary satellites;},
Abstract = {It is generally accepted that Io is the source of S, O, Na
and K which, after ionization, form the constituents of the
Io plasma torus. The escape of S and O from Io can be
understood in terms of the photochemistry of a predominantly
SO2 atmosphere created by the high vapour pressure of SO2
(refs 1,15). However, the vapour pressures of Na2S, K2S and
other common compounds containing Na and K are negligible at
the surface temperatures of Io. This has given rise to the
suggestion that over part of Io's surface (the nightside)
the atmosphere is thin enough so that surface sputtering by
co-rotating ions can eject Na and K directly into the Io
torus2,3. The main objection to this idea is that it implies
a 'Sun-locked' source for Na and K, while observations of
the Na and K clouds around Io indicate a 'Jupiter-locked'
ejection mechanism. We propose here that Na and K escape
from Io in two stages. Atoms of Na and K are first sputtered
into the atmosphere from the surface by high-energy
magnetospheric ions. Atmospheric sputtering4 by low-energy
co-rotating ions then removes these constituents (along with
others present) out of Io's gravitational field. We suggest
that the observed Na and K ejection asymmetry is due to
preferential sputtering of atmospheric particles on the
hemisphere of Io facing Jupiter. The estimated injection
rates are sufficiently large to maintain the observed K, Na,
and O clouds observed around Io5-7,18. © 1983 Nature
Publishing Group.},
Doi = {10.1038/304710a0},
Key = {2136743}
}
@article{2150608,
Author = {Haff, PK},
Title = {Grain flow as a fluid mechanical phenomenon},
Journal = {Journal of Fluid Mechanics},
Volume = {134},
Number = {-1},
Pages = {401-430},
Publisher = {Cambridge University Press (CUP)},
Year = {1983},
Month = {January},
url = {http://dx.doi.org/10.1017/S0022112083003419},
Keywords = {fluid dynamics;},
Abstract = {The behaviour of granular material in motion is studied from
a continuum point of view. Insofar as possible, individual
grains are treated as the ‘molecules’ of a granular
‘fluid'. Besides the obvious contrast in shape, size and
mass, a key difference between true molecules and grains is
that collisions of the latter are inevitably inelastic.
This, together with the fact that the fluctuation velocity
may be comparable to the flow velocity, necessitates
explicit incorporation of the energy equation, in addition
to the continuity and momentum equations, into the
theoretical description. Simple ‘microscopic’ kinetic
models are invoked for deriving expressions for the
‘coefficients’ of viscosity, thermal diffusivity and
energy absorption due to collisions. The ‘coefficients’
are not constants, but are functions of the local state of
the medium, and therefore depend on the local
‘temperature’ and density. In general the resulting
equations are nonlinear and coupled. However, in the limits
≪d, wheres is the mean separation between neighbouring
grain surfaces and is a grain diameter, the above equations
become linear and can be solved analytically. An important
dependent variable, in this formulation, in addition to the
flow velocity u, is the mean random fluctuation ('thermal')
velocity v of an individual grain. With a sufficient flux of
energy supplied to the system through the boundaries of the
container, v can remain non zero even in the absence of
flow. The existence of a non uniform v is the means by which
energy can be ‘conducted’ from one part of the system to
another. Because grain collisions are inelastic, there is a
natural (damping) lengthscale, governed by the value of d,
which strongly influences the functional dependence of v on
position. Several illustrative examples of static (u = 0)
systems are solved. As an example of grain flow, various
Couette type problems are solved analytically. The pressure,
shear stress, and ‘thermal’ velocity function v are all
determined by the relative plate velocity U (and the
boundary conditions). If v is set equal to zero at both
plates, the pressure and stress are both proportional to
U2i.e. the fluid is non-Newtonian. However, if sufficient
energy is supplied externally through the walls (v ≠ 0
there), then the forces become proportional to the first
power of U. Some examples of Couette flow are given which
emphasize the large effect on the grain system properties of
even a tiny amount of inelasticity in grain—grain
collisions. From these calculations it is suggested that,
for the case of Couette flow, the flow of sand is supersonic
over most of the region between the confining plates. ©
1983, Cambridge University Press. All rights
reserved.},
Doi = {10.1017/S0022112083003419},
Key = {2150608}
}
@article{2235268,
Author = {Haff, PK and Eviatar, A and Siscoe, GL},
Title = {Ring and plasma: The enigmae of Enceladus},
Journal = {Icarus},
Volume = {56},
Number = {3},
Pages = {426-438},
Publisher = {Elsevier BV},
Year = {1983},
Month = {January},
ISSN = {0019-1035},
url = {http://dx.doi.org/10.1016/0019-1035(83)90164-1},
Keywords = {planetary atmospheres;planetary rings;planetary
satellites;plasma;Saturn;sputtering;},
Abstract = {The E ring associated with the Kronian moon Enceladus has a
lifetime of only a few thousand years against sputteringly
by slow corotating O ions. The existence of the ring implies
the necessity for a continuous supply of matter. Possible
particle source mechanisms on Enceladus include meteoroidal
impact ejection and geysering. Estimates of ejection rates
of particulate debris following small meteoroid impact are
on the order of 3 × 10-18 g cm-2 sec-1, more than an order
of magnitude too small to sustain the ring. A geyser source
would need to generate a droplet supply at a rate of
approximately 10-16 g cm-2 sec- in order to account for a
stable ring. Enceladus and the ring particles also directly
supply both plasma and vapor to space via sputtering. The
absence of a 60 eV plasma at the Voyager 2 Enceladus L-shell
crossing, such as might have been expected from sputtering,
cannot be explained by absorption and moderation of plasma
ions by ring particles, because the ring is too diffuse.
Evidently, the effective sputtering yield in the vicinity of
Enceladus is on the order of, or smaller than, 0.4, about an
order of magnitude less than the calculated value. Small
scale surface roughness may account for some of this
discrepancy. © 1983.},
Doi = {10.1016/0019-1035(83)90164-1},
Key = {2235268}
}
@article{fds281139,
Author = {Haff, PK and Seiberling, LE},
Title = {Anomalous sputtering at high energy},
Journal = {Nature},
Volume = {290},
Number = {5807},
Pages = {544-545},
Publisher = {Springer Nature},
Year = {1981},
Month = {December},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/290544a0},
Doi = {10.1038/290544a0},
Key = {fds281139}
}
@article{1825595,
Author = {Haff, PK and Watson, CC and Tombrello, TA},
Title = {Possible isotopic fractionation effects in materials
sputtered from minerals.},
Journal = {Journal of Geophysical Research},
Volume = {86},
Number = {B10},
Pages = {9553-9561},
Publisher = {American Geophysical Union (AGU)},
Year = {1981},
Month = {January},
url = {http://dx.doi.org/10.1029/JB086iB10p09553},
Keywords = {isotope relative abundance;isotope separation;lunar rocks
and minerals;meteorites;minerals;oxygen;sputtering;},
Abstract = {A mathematical model is given which predicts fractionation
of isotopes during sputtering. -K.A.R.},
Doi = {10.1029/JB086iB10p09553},
Key = {1825595}
}
@article{1809592,
Author = {Haff, PK and Watson, CC and Yung, YL},
Title = {Sputter ejection of matter from Io},
Journal = {J. Geophys. Res. (Usa)},
Volume = {86},
Number = {A8},
Pages = {6933-6938},
Year = {1981},
Keywords = {Jupiter;planetary atmospheres;planetary satellites;},
Abstract = {The direct collisional interaction of magnetospheric
particles with Io will lead to sputtering of atoms and
molecules from the satellite into circum-Jovian space. The
~520-eV S (and ~260-eV O) ions composing the Io torus are
the most effective agents for net sputter removal of matter
from the satellite. An incident flux of ~1010 cm-2 s-1 is
estimated to provide ~5×1010 S atoms cm-2 s-1 from
sputtering of a (dayside) atmosphere with an exobase at a
few hundred kilometers and up to ~1012 S atoms cm-2 s-1 from
an atmosphere at 1500K with an exobase at ~2.2 RIo. The
supply of S (and O) required to stabilize the torus has been
estimated. If Na and K are present in the atmosphere at a
concentration level of 1%, the corresponding sputtering
rates are calculated. Sputtering can also remove heavy
molecules, like Sn, from the atmosphere. All atomic species
residing on the surface must be ejected into circum-Jovian
space at a rate approximately proportional to their
(surface) abundances, if direct surface sputtering occurs,
so that the particle content of the inner Jovian
magnetosphere should map rather faithfully all species
present on Io's surface},
Key = {1809592}
}
@article{fds328740,
Author = {Haff, PK and Watson, CC and Yung, YL},
Title = {Sputter ejection of matter from Io},
Journal = {Journal of Geophysical Research},
Volume = {86},
Number = {A8},
Pages = {6933-6933},
Publisher = {American Geophysical Union (AGU)},
Year = {1981},
url = {http://dx.doi.org/10.1029/ja086ia08p06933},
Doi = {10.1029/ja086ia08p06933},
Key = {fds328740}
}
@article{81020001625,
Author = {Watson, CC and Haff, PK},
Title = {Sputter-induced isotopic fractionation at solid
surfaces},
Journal = {Journal of Applied Physics},
Volume = {51},
Number = {1},
Pages = {691-699},
Publisher = {AIP Publishing},
Year = {1980},
Month = {December},
url = {http://dx.doi.org/10.1063/1.327327},
Keywords = {SPUTTERING;},
Abstract = {Elemental and isotopic mass fractionation in both binary and
multicomponent media are investigated within the framework
of the familiar collision-cascade model for sputtering. Some
of the most salient features of the phenomenon are
explicable on this basis. It is found that the partitioning
of beam-deposited energy among the various target components
can account for differentiations in the secondary recoil
fluxes only on the order of one part per thousand,
indicating the importance of the surface potentials when
large enrichment effects occur. A mechanism governing the
translation of internal recoil fluxes into external
sputtered fluxes is proposed in order to account for
isotopic fractionation, for which the surface binding
effects are assumed to be negligible. The predicted initial
fractionations are δf( 40Ca : 44Ca) =33 parts per thousand
in the calcium-containing mineral plagioclase and δf(40Ca :
44Ca) =24 parts per thousand in CaF2, in reasonable
agreement with recent data on isotopic fractionation.},
Doi = {10.1063/1.327327},
Key = {81020001625}
}
@article{fds281138,
Author = {Watson, CC and Haff, PK and Tombrello, TA},
Title = {Solar wind sputtering effects in the atmospheres of Mars and
Venus.},
Journal = {Geochimica Et Cosmochimica Acta, Supplement},
Volume = {14},
Number = {3},
Pages = {2479-2502},
Year = {1980},
Month = {January},
Abstract = {The consequences of the direct collisional interaction of an
energetic particle flux with the neutral components of a
planetary atmosphere were investigated. A combination of
Monte Carlo simulations and analytical analysis suggests
that solar wind sputtering could provide an important
exospheric mass sink on both Mars and Venus under
appropriate conditions. Sputtering of the venusian
atmosphere may result in loss of He at the rate of approx
105 atoms/cm2-sec, and sputtering of the martian atmosphere
could remove C, N, and O at the rates of 1 X 106 C
atoms/cm2-sec, 5 X 105 N atoms/cm2-sec, and 3 X 106 O
atoms/cm2-sec. Calculations based on a model martian
atmosphere suggest that 99% of the N2 and 43% of the CO2
originally present could have been sputtered away over 4.5 X
109 yr. -P.Br.},
Key = {fds281138}
}
@article{1541656,
Author = {Haff, PK and Watson, CC},
Title = {The erosion of planetary and satellite atmospheres by
energetic atomic particles},
Journal = {Journal of Geophysical Research},
Volume = {84},
Number = {B14},
Pages = {8436-8436},
Publisher = {American Geophysical Union (AGU)},
Address = {Pasadena, TX, USA},
Year = {1979},
ISSN = {0148-0227},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1979JH89800048&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {Jupiter;Mars;planetary atmospheres;planetary
satellites;solar wind;},
Abstract = {Analytic expressions are presented which may be used to
compute the sputter-erosion yield from any unimolecular
gravitationally bound gas by any atomic charged particle of
energy. A calculation of solar wind proton and alpha
particle induced erosion of the CO<sub>2</sub> atmosphere of
Mars predicts molecular sputtering yields
<i>S</i><sub>p</sub>≈0.029 and <i>S</i><sub>α</sub>≈0.21.
These numbers are comparable to the results of earlier Monte
Carlo simulations. An expression for the emission yield of
energetic molecular fragments produced in primary knock-on
events is also given in closed form. Such fragment emission
is of secondary importance for mass loss compared to the
molecular yield itself. Erosion by radiation belt protons of
a hypothetical thin O<sub>2</sub> atmosphere associated with
the Jovian satellite. Ganymede is considered. Molecular
sputtering yields for proton energies at 1 keV and 1 MeV are
0.115 and 6.4×10<sup>-4</sup>, respectively. The yield
at the lower energy can have significant effects on
atmospheric equilibrium should keV proton fluxes equal or
exceed about 10<sup>8</sup> cm<sup>-2</sup>
s<sup>-1</sup>},
Doi = {10.1029/jb084ib14p08436},
Key = {1541656}
}
@article{1205543,
Author = {Haff, PK and Switkowski, ZE and Tombrello, TA},
Title = {Solar-wind sputtering of the martian atmosphere},
Journal = {Nature},
Volume = {272},
Number = {5656},
Pages = {803-804},
Publisher = {Springer Nature},
Year = {1978},
Month = {December},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/272803a0},
Keywords = {Mars;planetary atmospheres;solar wind;},
Abstract = {In the sputtering process an incident particle beam loses
part of its energy to recoil motion of target atoms, some of
which may escape through a nearby surface. The sputtering
yield is defined as the number of atoms ejected per incident
particle. In the solar system, sputtering will occur
whenever the solar wind, consisting mainly of 1 keV
AMU<sup>-1</sup> hydrogen and helium ions, strikes a
material body. Wehner et al. (1963) suggested that solar
wind-induced sputtering of the lunar surface should be an
important cause of erosion; recently, analyses of returned
lunar material have been interpreted quantitatively in terms
of such solar-wind sputtering. Mars provides another example
of the interaction of the solar wind with a planetary body.
However, in contrast to the lunar surface, the Martian
surface is largely protected from direct solar wind
bombardment by its atmosphere. The primarily CO<sub>2</sub>
atmosphere is thin by terrestrial standards but still opaque
to the solar wind. The authors discuss whether solar-wind
sputtering of the Martian atmosphere is a mechanism leading
to significant mass loss},
Doi = {10.1038/272803a0},
Key = {1205543}
}
@article{1127815,
Author = {Haff, PK},
Title = {A model for surface layer composition changes in sputtered
alloys and compounds},
Journal = {Applied Physics Letters},
Volume = {31},
Number = {4},
Pages = {259-260},
Publisher = {AIP Publishing},
Year = {1977},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.89652},
Keywords = {sputtering;surface structure;},
Abstract = {Under the assumption that extracted beam energy is quickly
shared among secondary cascade members of all masses, we
present a model which accounts quantitatively for recently
observed equilibrium surface enrichments in heavy atoms
following ion bombardment of alloys and compounds. Assuming
strong radiation-driven diffusion, effects of which are
directly observed, and given the time required to reach
equilibrium, we can calculate the thickness Δx of the
enriched layer. Alternatively, knowing Δx, a calculation of
the equilibration time constant is possible.},
Doi = {10.1063/1.89652},
Key = {1127815}
}
@article{77120003324,
Author = {Haff, PK and Switkowski, ZE},
Title = {Ion-beam-induced atomic mixing},
Journal = {Journal of Applied Physics},
Volume = {48},
Number = {8},
Pages = {3383-3386},
Publisher = {AIP Publishing},
Year = {1977},
Month = {December},
url = {http://dx.doi.org/10.1063/1.324179},
Keywords = {SURFACES;MICROANALYSIS;},
Abstract = {Calculations based on the diffusion model are presented of
atomic mixing by ion bombardment. This mixing is assumed to
have its basis, as does sputtering, in the collision
cascades generated by the primary beam. Sharp interfaces
within a target are seen to be smoothed by ion bombardment.
Mixing may place fundamental limits on the resolution of ion
microprobes.},
Doi = {10.1063/1.324179},
Key = {77120003324}
}
@article{1124904,
Author = {Scalo, JM and Haff, PK and Switkowski, ZE and Tombrello,
TA},
Title = {Sputtering by fast electrons},
Journal = {Physics Letters B},
Volume = {70},
Number = {1},
Pages = {137-140},
Publisher = {Elsevier BV},
Year = {1977},
Month = {September},
ISSN = {0370-2693},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1977DV04400034&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {carbon;electron impact;iron;sputtering;},
Abstract = {Calculations are presented of collision cascade and knockon
contributions to sputtering induced by fast electrons. The
sputtering yield for MeV electrons bombarding carbon and
iron is found to be ≈10-7 to 10-6. Important erosion
effects on astrophysical grains are possible. ©
1977.},
Doi = {10.1016/0370-2693(77)90362-8},
Key = {1124904}
}
@article{1202092,
Author = {Switkowski, ZE and Haff, PK and Tombrello, TA and Burnett,
DS},
Title = {Mass fractionation of the lunar surface by solar wind
sputtering},
Journal = {Journal of Geophysical Research},
Volume = {82},
Number = {26},
Pages = {3797-3804},
Publisher = {American Geophysical Union (AGU)},
Year = {1977},
Month = {September},
ISSN = {0148-0227},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1977DW03900013&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {isotope relative abundance;Moon;solar wind;},
Abstract = {The sputtering of the lunar surface by the solar wind is
examined as a possible mechanism of mass fractionation.
Simple arguments based on current theories of sputtering and
the ballistics of the sputtered atoms suggest that most
ejected atoms will have sufficiently high energy to escape
lunar gravity. However, the fraction of atoms which falls
back to the surface is enriched in the heavier atomic
components in relation to the lighter ones. This material is
incorporated into the heavily radiation-damaged outer
surfaces of grains, where it is subject to resputtering.
Calculations predict that an equilibrium surface layer,
enriched in heavier atoms, will form with
δ(<sup>18</sup>O)≈+20<sup>0</sup>/<sub>00</sub>≈δ(<sup>30</sup>Si)
and that oxygen will be depleted on the surface layers of
grains relative to the bulk composition by about 12.5%.
These results are in fair agreement with
experiment},
Doi = {10.1029/jb082i026p03797},
Key = {1202092}
}
@article{1112600,
Author = {Haff, PK},
Title = {Low energy muonic hydrogen reactions with heavy
atoms},
Journal = {Physics Letters A},
Volume = {62},
Number = {5},
Pages = {301-302},
Publisher = {Elsevier BV},
Year = {1977},
Month = {September},
ISSN = {0375-9601},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1977DT60000007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {muon capture;muonic atoms;},
Abstract = {Average s-wave cross-sections appropriate for liquid
hydrogen temperatures are calculated with the aid of an
in-coming wave boundary condition for the muon transfer
process μ-p + Z → (μ-Z)* + p on heavy atoms. The
surface-correlated nature of the heavy atom X-rays is
emphasized. © 1977.},
Doi = {10.1016/0375-9601(77)90422-4},
Key = {1112600}
}
@article{1073512,
Author = {Haff, PK and Vogel, P},
Title = {Transport properties of negative muons in
matter},
Journal = {Physical Review A},
Volume = {15},
Number = {3},
Pages = {1336-1337},
Publisher = {American Physical Society (APS)},
Year = {1977},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.15.1336},
Keywords = {energy loss of particles;muon capture;muon probes;radiation
chemistry;},
Abstract = {In deriving a formula for atomic capture ratios involving
negative muons, Daniel postulates a model leading to a muon
energy spectrum of a different character from that indicated
by a more complete analysis. In this Comment we emphasize
the dependence of the energy spectrum on both inelastic and
capture processes, and suggest several experiments which may
distinguish between different theoretical models. © 1977
The American Physical Society.},
Doi = {10.1103/PhysRevA.15.1336},
Key = {1073512}
}
@article{1055719,
Author = {Haff, PK and Rodrigo, E and Tombrello, TA},
Title = {Muon transfer in gas targets},
Journal = {Annals of Physics},
Volume = {104},
Number = {2},
Pages = {363-379},
Publisher = {Elsevier BV},
Year = {1977},
Month = {January},
ISSN = {0003-4916},
url = {http://dx.doi.org/10.1016/0003-4916(77)90336-0},
Keywords = {atomic inelastic collisions;energy loss of particles;muonic
atoms;nuclear bombardment targets;},
Abstract = {The transfer of a negative muon from a proton to a heavy
atom Q, μ-p + Q → p + μ-Q, is treated in terms of a
classical description of the μp trajectory. We discuss the
muon transfer rate itself, the subsequent population of
states in the atom Q, and the effects of electron screening.
The polarizability of the μp atom emerges as a crucial
factor in the transfer process. © 1977.},
Doi = {10.1016/0003-4916(77)90336-0},
Key = {1055719}
}
@article{fds281136,
Author = {Haff, PK},
Title = {Low energy muonic hydrogen reactions with heavy
atoms},
Journal = {Physics Letters A},
Volume = {62},
Number = {5},
Pages = {301-302},
Year = {1977},
ISSN = {0375-9601},
Abstract = {Average s-wave cross-sections appropriate for liquid
hydrogen temperatures are calculated with the aid of an
in-coming wave boundary condition for the muon transfer
process μ-p + Z → (μ-Z)* + p on heavy atoms. The
surface-correlated nature of the heavy atom X-rays is
emphasized. © 1977.},
Key = {fds281136}
}
@article{fds281137,
Author = {Scalo, JM and Haff, PK and Switkowski, ZE and Tombrello,
TA},
Title = {Sputtering by fast electrons},
Journal = {Physics Letters B},
Volume = {70},
Number = {1},
Pages = {137-140},
Year = {1977},
ISSN = {0370-2693},
Abstract = {Calculations are presented of collision cascade and knockon
contributions to sputtering induced by fast electrons. The
sputtering yield for MeV electrons bombarding carbon and
iron is found to be ≈10-7 to 10-6. Important erosion
effects on astrophysical grains are possible. ©
1977.},
Key = {fds281137}
}
@article{1004301,
Author = {Haff, PK and Switkowski, ZE},
Title = {On the sputtering of binary compounds},
Journal = {Applied Physics Letters},
Volume = {29},
Number = {9},
Pages = {549-551},
Publisher = {AIP Publishing},
Year = {1976},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.89180},
Keywords = {copper alloys;gold alloys;nickel alloys;platinum
alloys;silicon alloys;sputtering;},
Abstract = {A simple physical model is presented to describe some
aspects of the sputtering of compound targets. In
particular, expressions are developed for the partial
sputtering yields for binary systems in terms of the
elemental sputtering rates, the stoichiometric
concentrations, and surface binding energy. The partial
yields depend nonlinearly on the bulk target concentrations.
Comparison of the theoretical predictions with the data on
sputtering of PtSi, NiSi, and Cu3Au indicates that the
general features are well described.},
Doi = {10.1063/1.89180},
Key = {1004301}
}
@article{993008,
Author = {Haff, PK},
Title = {Possible new sputtering mechanism in track registering
materials},
Journal = {Applied Physics Letters},
Volume = {29},
Number = {8},
Pages = {473-475},
Publisher = {AIP Publishing},
Year = {1976},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.89126},
Keywords = {energy loss of particles;ion beam effects;particle track
visualisation;sputtering;},
Abstract = {The "ion explosion" model of track production in dielectric
materials in investigated as a possible source of sputtered
particles at high bombarding energies.},
Doi = {10.1063/1.89126},
Key = {993008}
}
@article{893235,
Author = {Wilets, L and Tuerpe, DR and Haff, PK},
Title = {Calculation of the mass parameter in the theory of
self-cranked generator coordinates},
Journal = {Physical Review C},
Volume = {12},
Number = {6},
Pages = {2088-2093},
Publisher = {American Physical Society (APS)},
Year = {1975},
Month = {January},
ISSN = {0556-2813},
url = {http://dx.doi.org/10.1103/PhysRevC.12.2088},
Keywords = {nuclear mass;nuclear shape;nuclear theory;nuclei with
90⩽a⩽149;},
Abstract = {The self-cranked generator coordinate (SCGC) method of Haff
and Wilets, together with constrained Hartree-Fock-Bogoliubov
wave functions, has been used to calculate the mass
parameter BQ for quadrupole deformations. A simple ansatz
reduces the required integrals to a form similar to that
required in Hartree-Fock calculations, and the same matrix
elements of the Hamiltonian occur in both cases. The results
are sensitive to numerical approximations and care must be
exercised to maintain accuracy. Since the SCGC method adds
another variational function, the energy is lowered relative
to the usual generator coordinate method, and hence BQ is
increased. For a particular sample calculation, the
correction more than doubled BQ. NUCLEAR STRUCTURE
Self-cranked generator coordinate method employed to
calculate quadrupole mass parameter and potential energy.
Constrained Hartree-Fock-Bogoliubov wave functions. Ru108.
© 1975 The American Physical Society.},
Doi = {10.1103/PhysRevC.12.2088},
Key = {893235}
}
@article{864882,
Author = {Vogel, P and Haff, PK and Akylas, V and Winther, A},
Title = {Muon capture in atoms, crystals and molecules},
Journal = {Nuclear Physics A},
Volume = {254},
Number = {2},
Pages = {445-479},
Publisher = {Elsevier BV},
Year = {1975},
ISSN = {0375-9474},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1975AZ72200017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Keywords = {energy loss of particles;mesic and muonic atoms;muon
capture;},
Abstract = {The slowing down and capture of negative muons in solids is
discussed on the basis of classical equations of motion
where the energy dissipation is described in terms of
frictional forces. Transport equations determining the
energy distribution of the muons in the target are
formulated and solved for various models. Using a
statistical model of the atom it is shown that the muons are
captured typically at energies of a few tens of electron
volts, that the angular momentum distribution of the muons
at capture is almost statistical, and that this distribution
is not expected to be qualitatively changed by the
subsequent cascade to the tightly bound orbits. In mixtures
of atoms with atomic numbers Z1 and Z2 the capture ratio is
to a good approximation proportional to the atomic
concentration and, in the statistical model, proportional to
( Z1 Z2) 7 6. Calculations are also performed with more
accurate atomic models, and it is shown that capture ratios
as well as angular momentum distributions are influenced by
the ionicity of the atomic bonds and the atomic shell
structure. No systematic study of these effects has been
made but the few results obtained seem to be in reasonable
agreement with experiments. © 1975.},
Doi = {10.1016/0375-9474(75)90230-4},
Key = {864882}
}
@article{686747,
Author = {Haff, PK and Wilets, L},
Title = {Mass parameter in nuclear quadrupole motion},
Journal = {Physical Review C},
Volume = {10},
Number = {1},
Pages = {353-365},
Publisher = {American Physical Society (APS)},
Year = {1974},
Month = {January},
ISSN = {0556-2813},
url = {http://dx.doi.org/10.1103/PhysRevC.10.353},
Keywords = {BCS theory;nuclear collective model;nuclear
mass;},
Abstract = {The self-cranked generator coordinate (SCGC) formalism
described earlier for computing the mass parameter for
collective nuclear motion is cast into a form containing no
explicit reference to the Hamiltonian. The expression is
then specialized to the nuclear model of deformed harmonic
oscillators. The usual Gaussian overlap approximation is
eschewed in favor of direct evaluation of the appropriate
matrix elements. Exchange terms are handled by a
diagrammatic technique. The validity of certain assumptions
made in the derivation of the mass formula is tested
numerically. The effects of pairing and of short-range
Jastrow correlations are investigated. The SCGC mass
parameter is computed for several N=Z nuclei and found to be
smaller than either the cranking or the irrotational values,
if no correlations are included. The inclusion of
short-range correlations is shown to lead to important
changes in the value of the mass parameter. NUCLEAR
STRUCTURE Quadrupole mass parameter calculated. Self-cranked
generator coordinate formalism. Correlations included.
Compared to irrotational flow values. © 1974 The American
Physical Society.},
Doi = {10.1103/PhysRevC.10.353},
Key = {686747}
}
@article{695562,
Author = {Griffith, JE and Haff, PK and Tombrello, TA},
Title = {Energy levels of highly excited muonic atoms},
Journal = {Annals of Physics},
Volume = {87},
Number = {1},
Pages = {1-16},
Publisher = {Elsevier BV},
Year = {1974},
Month = {January},
ISSN = {0003-4916},
url = {http://dx.doi.org/10.1016/0003-4916(74)90444-8},
Keywords = {angular momentum theory;atomic structure;mesic and muonic
atoms;},
Abstract = {Energy levels of muonic atom states with high principal
quantum number are examined. A Thomas-Fermi type treatment
is used in all but the lightest atoms to take account of the
effects of electron shielding. Transition energies of the
muon are compared to electron binding energies, and
implications for muon lifetimes are discussed. The splitting
of angular momentum substates is explicitly studied;
transitions with no change in principal quantum number are
unlikely to be important. Effective charges for the muon are
computed. The possibility of an absorptive component of the
muon potential is raised. © 1974.},
Doi = {10.1016/0003-4916(74)90444-8},
Key = {695562}
}
@article{687073,
Author = {Haff, PK and Tombrello, TA},
Title = {Negative muon capture in very light atoms},
Journal = {Annals of Physics},
Volume = {86},
Number = {1},
Pages = {178-192},
Publisher = {Elsevier BV},
Year = {1974},
Month = {January},
ISSN = {0003-4916},
url = {http://dx.doi.org/10.1016/0003-4916(74)90435-7},
Keywords = {helium atoms;hydrogen neutral atoms;lithium;mesic and muonic
atoms;muon capture;},
Abstract = {The transition rates for unbound muons to be captured into
atomic bound states are calculated as functions of (1)
incident muon center-of-mass energy, (2) muon principal
quantum number n, and (3) muon (final) angular momentum l,
for the hydrogen, helium, and lithium atoms. These rates
reflect differences in electron binding energies. At muon
energies of several hundred electron volts, lithium K-shell
electrons are more likely to be ejected than the L-shell
electron, while this behavior is reversed for energies ≲
10 eV. However, in each case when the capture rate is folded
with a muon stopping power function, the result is that more
than half of the unbound muons are absorbed above 75 eV.
Implications for experiments which look at muon transfer
processes are noted. © 1974.},
Doi = {10.1016/0003-4916(74)90435-7},
Key = {687073}
}
@article{fds304958,
Author = {Haff, PK and Vogel, P and Winther, A},
Title = {Capture of negative muons in atoms},
Journal = {Physical Review A},
Volume = {10},
Number = {4},
Pages = {1430-1432},
Publisher = {American Physical Society (APS)},
Year = {1974},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.10.1430},
Abstract = {The frictional force derived from the stopping power of an
electron gas is used in the classical equation of motion for
the negative muons. We calculate the energy spectrum of the
captured muons and the angular momentum distribution of
muons at the energy of the electronic K orbit. The resulting
P(l) distribution closely resembles the statistical 2l+1
distribution. © 1974 The American Physical
Society.},
Doi = {10.1103/PhysRevA.10.1430},
Key = {fds304958}
}
@article{724100,
Author = {Haff, PK and Vogel, P and Winther, A},
Title = {Capture of negative muons in atoms},
Journal = {Phys. Rev. A, Gen. Phys. (Usa)},
Volume = {10},
Number = {14},
Pages = {1430-1432},
Year = {1974},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.10.1430},
Keywords = {mesic and muonic atoms;},
Abstract = {The effect of the collisions experienced by a muon moving
through an atom may be described by introducing a frictional
force in the classical equations of motion. In the region of
the electronic K shell, the Auger transitions should be
treated quantum-mechanically. This calculation of the energy
spectrum of the captured muons and the angular momentum
distributions of muons at the electronic K orbit includes
the interrelation between the stopping power of the electron
gas and capture. There is a close resemblance between the
P(L) distribution of angular momentum and the statistical
2L+1 distribution},
Doi = {10.1103/PhysRevA.10.1430},
Key = {724100}
}
@article{510640,
Author = {Haff, PK and Wilets, L},
Title = {Microscopic theory of nuclear collective
motion},
Journal = {Physical Review C},
Volume = {7},
Number = {3},
Pages = {951-968},
Publisher = {American Physical Society (APS)},
Year = {1973},
Month = {January},
ISSN = {0556-2813},
url = {http://dx.doi.org/10.1103/PhysRevC.7.951},
Keywords = {nuclear collective model;},
Abstract = {A generalization of the Hill-Wheeler generator coordinate
method is applied to collective deformations. The intrinsic
wave function is constrained (as in constrained
Hartree-Fock) to be characterized not only by a given
deformation, but also by a deformation velocity. This is
effected by a simple ansatz which involves operation on the
singly constrained wave function by an exponentiated
single-particle deformation operator containing an arbitrary
function β(α), where α is the collective variable. The
expectation value of the energy is minimized with respect to
both β(α) and the Hill-Wheeler projection function f(α).
This leads to an integral equation for f which, upon
invoking the collective nature of the intrinsic states, may
be approximated by a second-order differential equation in
the deformation coordinate αQ. In order to reduce this
equation to the Schrödinger form, certain assumptions are
introduced with regard to the approximate form of f. This
procedure leads to two different differential equations for
f and to two mass parameters. One is valid in the classical
region and one in the classically inaccessible tunneling
region. This is to be contrasted to the cranking model where
sufficient energy must always be available to drive the
system. The expressions for the mass parameter are given in
terms of expectation values of few-body operators. The case
of uniform translation of the nucleus as a whole is studied
in detail. The generalized Hill-Wheeler method as described
above produces the correct mass (= total nuclear mass). This
rigorous reproduction of a known result allows the study of
approximations which become necessary for the general case
of deformations. Comments are made about the potential
energy of deformation surface, which is expected to lie
lower than the expectation value of the Hamiltonian. © 1973
The American Physical Society.},
Doi = {10.1103/PhysRevC.7.951},
Key = {510640}
}
@article{fds281133,
Author = {Haff, PK and Eisenberg, JM},
Title = {Dynamic nuclear effects in pionic and kaonic
atoms},
Journal = {Physics Letters B},
Volume = {33},
Number = {2},
Pages = {133-136},
Publisher = {Elsevier BV},
Year = {1970},
Month = {September},
ISSN = {0370-2693},
url = {http://dx.doi.org/10.1016/0370-2693(70)90281-9},
Abstract = {Corrections have been calculated to absorption widths in
pionic and kaonic atoms due to the admixture of excited
nuclear states. Effects as large as 12% and 27% are
indicated for pionic and kaonic atoms, respectively. ©
1970.},
Doi = {10.1016/0370-2693(70)90281-9},
Key = {fds281133}
}
%% Other
@misc{fds185790,
Author = {J. C. Roseberry and M. W. Schmeeckle and D. J. Furbish and P. K.
Haff},
Title = {A probabilistic definition of the bedload sediment flux:
Experiments},
Journal = {AGU abstract},
Year = {2010},
Key = {fds185790}
}
@misc{fds49955,
Author = {P. K. Haff},
Title = {Response of Desert Pavement to Seismic Shaking, Hector Mine
Earthquake, California},
Year = {2001},
Key = {fds49955}
}
@misc{fds49957,
Author = {P.K. Haff},
Title = {Neogeomorphology, Prediction, and the Anthropic
Landscape},
Year = {2001},
Key = {fds49957}
}
@misc{fds49951,
Author = {P.K. Haff},
Title = {Rivers and Blood - Allometric Scaling in Biology and River
Networks},
Journal = {Nature},
Volume = {408},
Pages = {159-2000},
Year = {2000},
Key = {fds49951}
}
@misc{fds49952,
Author = {Haff and Furbish},
Title = {Upslope Transport and Other Oddities of Landscape
Diffusion},
Year = {2000},
Key = {fds49952}
}
@misc{fds49953,
Author = {Furbish and Haff},
Title = {The Master Equation Applied to Landscape
Evolution},
Year = {2000},
Key = {fds49953}
}
@misc{fds49950,
Author = {Boring and Haff},
Title = {An Empirical Model of Large Scale Sediment Transport in Arid
Terrain: Application to Basalt Flow Erosion and Pediment
Evolution near the Cima Volcanic Field, Mojave Desert,
California},
Year = {1998},
Key = {fds49950}
}
@misc{fds328734,
Author = {Haff, PK},
Title = {Why prediction of grain behavior is difficult in geological
granular systems},
Journal = {Powders & Grains 97},
Pages = {61-64},
Publisher = {A A BALKEMA},
Editor = {Behringer, RP and Jenkins, JT},
Year = {1997},
Month = {January},
ISBN = {90-5410-884-3},
Key = {fds328734}
}
@misc{fds49947,
Author = {P.K. Haff},
Title = {Why prediction of grain behavior is difficult for geological
granular systems},
Year = {1997},
Key = {fds49947}
}
@misc{fds49949,
Author = {Boring and Haff},
Title = {Landscape Evolution Using Digital Elevation Models of the
Cima Dome Area, Mojave Desert, California},
Year = {1997},
Key = {fds49949}
}
@misc{fds328735,
Author = {Haff, PK},
Title = {Limitations on predictive modeling in geomorphology},
Journal = {Scientific Nature of Geomorphology},
Pages = {337-358},
Publisher = {JOHN WILEY & SONS LTD},
Editor = {Rhoads, BL and Thorn, CE},
Year = {1996},
Month = {January},
ISBN = {0-471-96811-0},
Key = {fds328735}
}
@misc{fds344724,
Author = {Gutt, GM and Haff, PK},
Title = {An automata model of granular materials},
Journal = {Proceedings of the 5th Distributed Memory Computing
Conference, Dmcc 1990},
Volume = {1},
Pages = {522-529},
Year = {1990},
Month = {January},
ISBN = {0818621133},
url = {http://dx.doi.org/10.1109/DMCC.1990.555429},
Abstract = {A new modeling technique (the Lattice Grain Model) is
presented for the simulation of two-dimensional granular
systems involving large numbers (- lo4 to 10') of grains.
These granular systems (e.g., rock slides, planetary rings,
industrial powders, etc.) may include both high shear rate
regions as well as static plugs of grains and cannot easily
be handled within the framework of existing continuum
theories such as soil mechanics. The Lattice Grain Model
(LGrM) is similar to the Lattice Gas Model (LGM), which was
introduced as a discrete model of fluids, in that the
computation is carried out by means of cellular automata
which evolve according to a simple set of rules based on
local interactions. This allows large simulations to be
programmed onto a hypercube concurrent processor in a
straightforward manner. However, it differs from LGM in that
it includes the inelastic collisions and volume-filling
properties of macroscopic grains. Examples to be presented
will include Couette flow, flow through an hourglass, and
gravity-driven flows around obstacles.},
Doi = {10.1109/DMCC.1990.555429},
Key = {fds344724}
}
@misc{fds331186,
Author = {Werner, BT and Haff, PK},
Title = {Dynamical sinulations of granular naterials using the
caltech hypercuee},
Journal = {Proceedings of the 3rd Conference on Hypercube Concurrent
Computers and Applications: Architecture, Software, Computer
Systems, and General Issues, C3p 1988},
Volume = {2},
Pages = {1313-1318},
Publisher = {ACM Press},
Year = {1989},
Month = {January},
ISBN = {0897912780},
url = {http://dx.doi.org/10.1145/63047.63085},
Abstract = {A technique for simulating the motion of granular materials
using the Caltech Hypercube is described, We demonstrate
that grain dynamics simulations run efficiently on the
Hypetcube and therefore that they offer an opportunity for
greatly expanding the use of parallel simulations in
studying granular materials. Several examples, which
illustrate how the simulations can be used to extract
information concerning the behavior of granular materials,
are discussed.},
Doi = {10.1145/63047.63085},
Key = {fds331186}
}
@misc{fds328741,
Author = {WATSON, CC and HAFF, PK},
Title = {MOMENTUM TRANSPORT IN A DENSE HARD-SPHERE
GAS},
Journal = {Bulletin of the American Physical Society},
Volume = {25},
Number = {4},
Pages = {531-531},
Year = {1980},
Key = {fds328741}
}
@misc{fds328742,
Author = {HAFF, PK},
Title = {GROWTH AND MAINTENANCE OF A MINERAL ARMOR ON THE ICY
SATELLITES OF JUPITER},
Journal = {Journal of the Electrochemical Society},
Volume = {126},
Number = {8},
Pages = {C342-C343},
Year = {1979},
Key = {fds328742}
}
@misc{fds328743,
Author = {WATSON, CC and HAFF, PK},
Title = {SPUTTERING OF A MOLECULAR GAS},
Journal = {Bulletin of the American Physical Society},
Volume = {24},
Number = {4},
Pages = {660-660},
Year = {1979},
Key = {fds328743}
}
@misc{fds328744,
Author = {HAFF, PK},
Title = {SPALLATION SPUTTERING BY FAST PROTONS},
Journal = {Bulletin of the American Physical Society},
Volume = {23},
Number = {4},
Pages = {564-564},
Year = {1978},
Key = {fds328744}
}
@misc{fds328745,
Author = {CREWTHER, DP and HAFF, PK and KELLOGG, WK},
Title = {ENERGY SHARING IN SLOW ATOMIC-COLLISIONS IN BINARY
MATERIALS},
Journal = {Bulletin of the American Physical Society},
Volume = {23},
Number = {1},
Pages = {101-102},
Year = {1978},
Key = {fds328745}
}
@misc{fds328746,
Author = {HAFF, PK and SWITKOWSKI, ZE and TOMBRELLO, TA and BURNETT,
DS},
Title = {SOLAR-WIND SPUTTERING OF LUNAR-SURFACE},
Journal = {Bulletin of the American Physical Society},
Volume = {22},
Number = {4},
Pages = {538-538},
Year = {1977},
Key = {fds328746}
}
@misc{fds328747,
Author = {HAFF, PK},
Title = {SURFACE ENRICHMENT INDUCED BY ION-BOMBARDMENT},
Journal = {Journal of the Electrochemical Society},
Volume = {124},
Number = {8},
Pages = {C291-C291},
Year = {1977},
Key = {fds328747}
}
@misc{fds328748,
Author = {HAFF, PK and VOGEL, P and AKYLAS, V and WINTHER, A},
Title = {MUON-CAPTURE IN GASES, GAS-MIXTURES, AND
CRYSTALS},
Journal = {Bulletin of the American Physical Society},
Volume = {20},
Number = {1},
Pages = {91-91},
Year = {1975},
Key = {fds328748}
}
@misc{fds328749,
Author = {HAFF, PK and GRIFFITH, JE and TOMBRELLO, TA},
Title = {QUANTUM CASCADE IN HIGHLY EXCITED MUONIC
ATOMS},
Journal = {Bulletin of the American Physical Society},
Volume = {20},
Number = {4},
Pages = {702-702},
Year = {1975},
Key = {fds328749}
}
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