%% Books
@book{fds3876,
Author = {G. Edwards},
Title = {Physical Mechanisms that Govern the Ablation of Biological
Tissue},
Series = {Volume 30: Laser Desorption and Ablation},
Booktitle = {Experimental Methods in the Physical Sciences.},
Publisher = {Academic Press},
Editor = {J.C. Miller and R.F. Haglund. R. Celotta and T. Lucatorto,
treatise},
Year = {1998},
Month = {January},
Key = {fds3876}
}
@book{fds3877,
Author = {M.L. Copeland and R. J. Maciunas and G.S. Edwards},
Title = {Use of the Free-Electron Laser for Metastatic Brain
Tumors},
Series = {The Anerican Association of Neurological
Surgeons},
Booktitle = {Neurosurgical Topics: Advanced Techniques in Central Nervous
System Metastases},
Editor = {R.J. Maciunas},
Year = {1998},
Month = {January},
Key = {fds3877}
}
%% Papers Published
@article{fds335576,
Author = {Aristotelous, AC and Crawford, JM and Edwards, GS and Kiehart, DP and Venakides, S},
Title = {Mathematical models of dorsal closure.},
Journal = {Progress in biophysics and molecular biology},
Volume = {137},
Pages = {111-131},
Year = {2018},
Month = {September},
url = {http://dx.doi.org/10.1016/j.pbiomolbio.2018.05.009},
Abstract = {Dorsal closure is a model cell sheet movement that occurs
midway through Drosophila embryogenesis. A dorsal hole,
filled with amnioserosa, closes through the dorsalward
elongation of lateral epidermal cell sheets. Closure
requires contributions from 5 distinct tissues and well over
140 genes (see Mortensen et al., 2018, reviewed in Kiehart
et al., 2017 and Hayes and Solon, 2017). In spite of this
biological complexity, the movements (kinematics) of closure
are geometrically simple at tissue, and in certain cases, at
cellular scales. This simplicity has made closure the target
of a number of mathematical models that seek to explain and
quantify the processes that underlie closure's kinematics.
The first (purely kinematic) modeling approach recapitulated
well the time-evolving geometry of closure even though the
underlying physical principles were not known. Almost all
subsequent models delve into the forces of closure (i.e. the
dynamics of closure). Models assign elastic, contractile and
viscous forces which impact tissue and/or cell mechanics.
They write rate equations which relate the forces to one
another and to other variables, including those which
represent geometric, kinematic, and or signaling
characteristics. The time evolution of the variables is
obtained by computing the solution of the model's system of
equations, with optimized model parameters. The basis of the
equations range from the phenomenological to biophysical
first principles. We review various models and present their
contribution to our understanding of the molecular
mechanisms and biophysics of closure. Models of closure will
contribute to our understanding of similar movements that
characterize vertebrate morphogenesis.},
Doi = {10.1016/j.pbiomolbio.2018.05.009},
Key = {fds335576}
}
@article{fds335575,
Author = {Lo, W-C and Madrak, C and Kiehart, DP and Edwards,
GS},
Title = {Unified biophysical mechanism for cell-shape oscillations
and cell ingression.},
Journal = {Physical review. E},
Volume = {97},
Number = {6-1},
Pages = {062414},
Year = {2018},
Month = {June},
url = {http://dx.doi.org/10.1103/physreve.97.062414},
Abstract = {We describe a mechanochemical and percolation cascade that
augments myosin's regulatory network to tune cytoskeletal
forces. Actomyosin forces collectively generate cytoskeletal
forces during cell oscillations and ingression, which we
quantify by elastic percolation of the internally driven,
cross-linked actin network. Contractile units can produce
relatively large, oscillatory forces that disrupt crosslinks
to reduce cytoskeletal forces. A (reverse) Hopf bifurcation
switches contractile units to produce smaller, steady forces
that enhance crosslinking and consequently boost
cytoskeletal forces to promote ingression. We describe
cell-shape changes and cell ingression in terms of
intercellular force imbalances along common cell
junctions.},
Doi = {10.1103/physreve.97.062414},
Key = {fds335575}
}
@article{fds329955,
Author = {Kiehart, DP and Crawford, JM and Aristotelous, A and Venakides, S and Edwards, GS},
Title = {Cell Sheet Morphogenesis: Dorsal Closure in Drosophila
melanogaster as a Model System.},
Journal = {Annual review of cell and developmental biology},
Volume = {33},
Pages = {169-202},
Year = {2017},
Month = {October},
url = {http://dx.doi.org/10.1146/annurev-cellbio-111315-125357},
Abstract = {Dorsal closure is a key process during Drosophila
morphogenesis that models cell sheet movements in chordates,
including neural tube closure, palate formation, and wound
healing. Closure occurs midway through embryogenesis and
entails circumferential elongation of lateral epidermal cell
sheets that close a dorsal hole filled with amnioserosa
cells. Signaling pathways regulate the function of cellular
structures and processes, including Actomyosin and
microtubule cytoskeletons, cell-cell/cell-matrix adhesion
complexes, and endocytosis/vesicle trafficking. These
orchestrate complex shape changes and movements that entail
interactions between five distinct cell types. Genetic and
laser perturbation studies establish that closure is robust,
resilient, and the consequence of redundancy that
contributes to four distinct biophysical processes:
contraction of the amnioserosa, contraction of supracellular
Actomyosin cables, elongation (stretching?) of the lateral
epidermis, and zipping together of two converging cell
sheets. What triggers closure and what the emergent
properties are that give rise to its extraordinary
resilience and fidelity remain key, extant
questions.},
Doi = {10.1146/annurev-cellbio-111315-125357},
Key = {fds329955}
}
@article{fds328148,
Author = {Lu, H and Sokolow, A and Kiehart, DP and Edwards,
GS},
Title = {Quantifying dorsal closure in three dimensions.},
Journal = {Molecular biology of the cell},
Volume = {27},
Number = {25},
Pages = {3948-3955},
Year = {2016},
Month = {December},
url = {http://dx.doi.org/10.1091/mbc.e16-06-0400},
Abstract = {Dorsal closure is an essential stage of Drosophila
embryogenesis and is a powerful model system for
morphogenesis, wound healing, and tissue biomechanics.
During closure, two flanks of lateral epidermis close an
eye-shaped dorsal opening that is filled with amnioserosa.
The two flanks of lateral epidermis are zipped together at
each canthus ("corner" of the eye). Actomyosin-rich purse
strings are localized at each of the two leading edges of
lateral epidermis ("lids" of the eye). Here we report that
each purse string indents the dorsal surface at each leading
edge. The amnioserosa tissue bulges outward during the
early-to-mid stages of closure to form a remarkably smooth,
asymmetric dome indicative of an isotropic and uniform
surface tension. Internal pressure of the embryo and tissue
elastic properties help to shape the dorsal
surface.},
Doi = {10.1091/mbc.e16-06-0400},
Key = {fds328148}
}
@article{fds321830,
Author = {Lu, H and Sokolow, A and Kiehart, DP and Edwards,
GS},
Title = {Remodeling Tissue Interfaces and the Thermodynamics of
Zipping during Dorsal Closure in Drosophila.},
Journal = {Biophysical journal},
Volume = {109},
Number = {11},
Pages = {2406-2417},
Year = {2015},
Month = {December},
url = {http://dx.doi.org/10.1016/j.bpj.2015.10.017},
Abstract = {Dorsal closure during Drosophila embryogenesis is an
important model system for investigating the biomechanics of
morphogenesis. During closure, two flanks of lateral
epidermis (with actomyosin-rich purse strings near each
leading edge) close an eye-shaped opening that is filled
with amnioserosa. At each canthus (corner of the eye) a
zipping process remodels the tissue interfaces between the
leading edges of the lateral epidermis and the amnioserosa.
We investigated zipping dynamics and found that apposing
leading edge cells come together at their apical ends and
then square off basally to form a lateral junction.
Meanwhile, the purse strings act as contractile elastic rods
bent toward the embryo interior near each canthus. We
propose that a canthus-localized force contributes to both
bending the ends of the purse strings and the formation of
lateral junctions. We developed a thermodynamic model for
zipping based on three-dimensional remodeling of the tissue
interfaces and the reaction dynamics of adhesion molecules
in junctions and elsewhere, which we applied to zipping
during unperturbed wild-type closure and to laser or
genetically perturbed closure. We identified two processes
that can contribute to the zipping mechanism, consistent
with experiments, distinguished by whether amnioserosa
dynamics do or do not augment canthus adhesion
dynamics.},
Doi = {10.1016/j.bpj.2015.10.017},
Key = {fds321830}
}
@article{fds245845,
Author = {Wells, AR and Zou, RS and Tulu, US and Sokolow, AC and Crawford, JM and Edwards, GS and Kiehart, DP},
Title = {Complete canthi removal reveals that forces from the
amnioserosa alone are sufficient to drive dorsal closure in
Drosophila.},
Journal = {Molecular biology of the cell},
Volume = {25},
Number = {22},
Pages = {3552-3568},
Year = {2014},
Month = {November},
ISSN = {1059-1524},
url = {http://dx.doi.org/10.1091/mbc.e14-07-1190},
Abstract = {Drosophila's dorsal closure provides an excellent model
system with which to analyze biomechanical processes during
morphogenesis. During native closure, the amnioserosa,
flanked by two lateral epidermal sheets, forms an eye-shaped
opening with canthi at each corner. The dynamics of
amnioserosa cells and actomyosin purse strings in the
leading edges of epidermal cells promote closure, whereas
the bulk of the lateral epidermis opposes closure. Canthi
maintain purse string curvature (necessary for their
dorsalward forces), and zipping at the canthi shortens
leading edges, ensuring a continuous epithelium at closure
completion. We investigated the requirement for intact
canthi during closure with laser dissection approaches.
Dissection of one or both canthi resulted in tissue recoil
and flattening of each purse string. After recoil and a
temporary pause, closure resumed at approximately native
rates until slowing near the completion of closure. Thus the
amnioserosa alone can drive closure after dissection of one
or both canthi, requiring neither substantial purse string
curvature nor zipping during the bulk of closure. How the
embryo coordinates multiple, large forces (each of which is
orders of magnitude greater than the net force) during
native closure and is also resilient to multiple
perturbations are key extant questions.},
Doi = {10.1091/mbc.e14-07-1190},
Key = {fds245845}
}
@article{fds225748,
Author = {Adrienne R. Wells and Roger S. Zou and U. Serdar Tulu and Adam C.
Sokolow and Janice M. Crawford and Glenn S. Edwards and Daniel P.
Kiehart},
Title = {Complete canthi removal reveals that forces from the
amnioserosa are alone sufficient to drive dorsal closure in
Drosophila},
Journal = {Molecular Biology of the Cell},
Year = {2014},
Month = {September},
ISSN = {seq001|0387964908},
Key = {fds225748}
}
@article{fds245894,
Author = {Sokolow, A and Toyama, Y and Kiehart, DP and Edwards,
GS},
Title = {Cell ingression and apical shape oscillations during dorsal
closure in Drosophila.},
Journal = {Biophysical journal},
Volume = {102},
Number = {5},
Pages = {969-979},
Year = {2012},
Month = {March},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22404919},
Abstract = {Programmed patterns of gene expression, cell-cell signaling,
and cellular forces cause morphogenic movements during
dorsal closure. We investigated the apical cell-shape
changes that characterize amnioserosa cells during dorsal
closure in Drosophila embryos with in vivo imaging of
green-fluorescent-protein-labeled DE-cadherin. Time-lapsed,
confocal images were assessed with a novel segmentation
algorithm, Fourier analysis, and kinematic and dynamical
modeling. We found two generic processes, reversible
oscillations in apical cross-sectional area and cell
ingression characterized by persistent loss of apical area.
We quantified a time-dependent, spatially-averaged sum of
intracellular and intercellular forces acting on each cell's
apical belt of DE-cadherin. We observed that a substantial
fraction of amnioserosa cells ingress near the leading edges
of lateral epidermis, consistent with the view that
ingression can be regulated by leading-edge cells. This is
in addition to previously observed ingression processes
associated with zipping and apoptosis. Although there is
cell-to-cell variability in the maximum rate for decreasing
apical area (0.3-9.5 μm(2)/min), the rate for completing
ingression is remarkably constant (0.83 cells/min, r(2) >
0.99). We propose that this constant ingression rate
contributes to the spatiotemporal regularity of mechanical
stress exerted by the amnioserosa on each leading edge
during closure.},
Doi = {10.1016/j.bpj.2012.01.027},
Key = {fds245894}
}
@article{fds303660,
Author = {Layton, AT and Toyama, Y and Yang, G-Q and Edwards, GS and Kiehart, DP and Venakides, S},
Title = {Drosophila morphogenesis: tissue force laws and the modeling
of dorsal closure.},
Journal = {HFSP journal},
Volume = {3},
Number = {6},
Pages = {441-460},
Year = {2009},
Month = {December},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20514134},
Abstract = {Dorsal closure, a stage of Drosophila development, is a
model system for cell sheet morphogenesis and wound healing.
During closure, two flanks of epidermal tissue progressively
advance to reduce the area of the eye-shaped opening in the
dorsal surface, which contains amnioserosa tissue. To
simulate the time evolution of the overall shape of the
dorsal opening, we developed a mathematical model, in which
contractility and elasticity are manifest in model
force-producing elements that satisfy force-velocity
relationships similar to muscle. The action of the elements
is consistent with the force-producing behavior of actin and
myosin in cells. The parameters that characterize the
simulated embryos were optimized by reference to
experimental observations on wild-type embryos and, to a
lesser extent, on embryos whose amnioserosa was removed by
laser surgery and on myospheroid mutant embryos. Simulations
failed to reproduce the amnioserosa-removal protocol in
either the elastic or the contractile limit, indicating that
both elastic and contractile dynamics are essential
components of the biological force-producing elements. We
found it was necessary to actively upregulate forces to
recapitulate both the double and single-canthus nick
protocols, which did not participate in the optimization of
parameters, suggesting the existence of additional key
feedback mechanisms.},
Doi = {10.2976/1.3266062},
Key = {fds303660}
}
@article{fds245896,
Author = {Edwards, GS},
Title = {Mechanisms for soft-tissue ablation and the development of
alternative medical lasers based on investigations with
mid-infrared free-electron lasers},
Journal = {Laser and Photonics Reviews},
Volume = {3},
Number = {6},
Pages = {545-555},
Publisher = {WILEY},
Year = {2009},
Month = {November},
ISSN = {1863-8880},
url = {DOI 10.1002/lpor.200810063},
Abstract = {Experimental evidence indicating the potential biomedical
advantages of using a Mark-III Free-Electron Laser (FEL) for
the ablation of soft tissue were first reported in 1994.
Research progress since that time is reviewed, including: 1)
successful human surgery using the Mark-III FEL; 2) advances
in understanding the physical mechanism for infrared tissue
ablation and how these mechanistic features correlate with
the preferential ablative properties; 3) the pursuit of
table-top, nanosecond-pulsed laser technology that mimics
the preferential ablation properties of the Mark-III FEL
with the aim of improving clinical acceptance of
mid-infrared laser ablation of soft tissue; and 4) current
research challenges. © 2009 by WILEY-VCH Verlag GmbH &
Co.KGaA, Weinheim.},
Doi = {10.1002/lpor.200810063},
Key = {fds245896}
}
@article{fds304534,
Author = {Wagner, W and Sokolow, A and Pearlstein, R and Edwards,
G},
Title = {Thermal vapor bubble and pressure dynamics during infrared
laser ablation of tissue},
Journal = {Applied Physics Letters},
Volume = {94},
Number = {1},
Pages = {013901-013901},
Publisher = {AIP Publishing},
Year = {2009},
Month = {January},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3063127},
Abstract = {Free-electron laser irradiation can superheat tissue water,
driving thermal vapor bubbles confined by tissue matrix and
leading to mechanical tissue failure (ablation). Acoustic
transients propagating from an ablation cavity were recorded
with a polarization quadrature, interferometric vibrometer.
For 3.0 μm infrared irradiation, the shocklike transients
with peak pressures in the megapascal range indicate
amplification due to bubble collapse. In contrast, for 6.45
μm irradiation, elastic transients with peak pressures in
the 0.1 MPa range indicate tissue failure during bubble
growth. © 2009 American Institute of Physics.},
Doi = {10.1063/1.3063127},
Key = {fds304534}
}
@article{fds245897,
Author = {Bush, WD and Garguilo, J and Zucca, FA and Bellei, C and Nemanich, RJ and Edwards, GS and Zecca, L and Simon, JD},
Title = {Neuromelanins isolated from different regions of the human
brain exhibit a common surface photoionization
threshold.},
Journal = {Photochemistry and photobiology},
Volume = {85},
Number = {1},
Pages = {387-390},
Year = {2009},
Month = {January},
ISSN = {0031-8655},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19067944},
Abstract = {Neuromelanin isolated from the premotor cortex, cerebellum,
putamen, globus pallidus and corpus callosum of the human
brain is studied by scanning probe and photoelectron
emission microscopies and the results are compared with
previously published work on neuromelanin from the
substantia nigra. Scanning electron microscopy reveals
common structure for all neuromelanins. All exhibit
spherical entities of diameters between 200 and 400 nm,
composed of smaller spherical substructures, approximately
30 nm in diameter. These features are similar to that
observed for many melanin systems including Sepia
cuttlefish, bovine eye, and human eye and hair melanosomes.
Photoelectron microscopy images were collected for all
neuromelanins at specific wavelengths of ultraviolet light
between 248 and 413 nm, using the spontaneous emission
output from the Duke free electron laser. Analysis of the
data establishes a common threshold photoionization
potential for neuromelanins of 4.7 +/- 0.2 eV, corresponding
to an oxidation potential of -0.3 +/- 0.2 V vs the normal
hydrogen electrode (NHE). These results are consistent with
previously reported potentials for neuromelanin from the
substantia nigra of 4.5 +/- 0.2 eV (-0.1 +/- 0.2 V vs NHE).
All neuromelanins exhibit a common low surface oxidation
potential, reflecting their eumelanic component and their
inability to trigger redox processes with neurotoxic
effect.},
Doi = {10.1111/j.1751-1097.2008.00476.x},
Key = {fds245897}
}
@article{fds245895,
Author = {Layton, AT and Toyama, Y and Yang, G-Q and Edwards, GS and Kiehart, DP and Venakides, S},
Title = {Drosophila Morphogenesis: Tissue Force Laws and the Modeling
of Dorsal Closure},
Journal = {Human Frontier Science Program Journal},
Volume = {3},
Number = {6},
Pages = {doi:10.2976/1.3266062},
Year = {2009},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20514134},
Abstract = {Dorsal closure, a stage of Drosophila development, is a
model system for cell sheet morphogenesis and wound healing.
During closure, two flanks of epidermal tissue progressively
advance to reduce the area of the eye-shaped opening in the
dorsal surface, which contains amnioserosa tissue. To
simulate the time evolution of the overall shape of the
dorsal opening, we developed a mathematical model, in which
contractility and elasticity are manifest in model
force-producing elements that satisfy force-velocity
relationships similar to muscle. The action of the elements
is consistent with the force-producing behavior of actin and
myosin in cells. The parameters that characterize the
simulated embryos were optimized by reference to
experimental observations on wild-type embryos and, to a
lesser extent, on embryos whose amnioserosa was removed by
laser surgery and on myospheroid mutant embryos. Simulations
failed to reproduce the amnioserosa-removal protocol in
either the elastic or the contractile limit, indicating that
both elastic and contractile dynamics are essential
components of the biological force-producing elements. We
found it was necessary to actively upregulate forces to
recapitulate both the double and single-canthus nick
protocols, which did not participate in the optimization of
parameters, suggesting the existence of additional key
feedback mechanisms.},
Doi = {10.2976/1.3266062},
Key = {fds245895}
}
@article{fds245898,
Author = {Wagner, W and Sokolow, A and Pearlstein, R and Edwards,
G},
Title = {Thermal Vapor Bubble and Pressure Dynamics During Infrared
Laser Ablation of Tissue},
Journal = {Applied Physics Letters},
Volume = {94},
Number = {013901},
Year = {2009},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3063127},
Abstract = {Free-electron laser irradiation can superheat tissue water,
driving thermal vapor bubbles confined by tissue matrix and
leading to mechanical tissue failure (ablation). Acoustic
transients propagating from an ablation cavity were recorded
with a polarization quadrature, interferometric vibrometer.
For 3.0 μm infrared irradiation, the shocklike transients
with peak pressures in the megapascal range indicate
amplification due to bubble collapse. In contrast, for 6.45
μm irradiation, elastic transients with peak pressures in
the 0.1 MPa range indicate tissue failure during bubble
growth. © 2009 American Institute of Physics.},
Doi = {10.1063/1.3063127},
Key = {fds245898}
}
@article{fds245901,
Author = {Toyama, Y and Peralta, XG and Wells, AR and Kiehart, DP and Edwards,
GS},
Title = {Apoptotic force and tissue dynamics during Drosophila
embryogenesis.},
Journal = {Science (New York, N.Y.)},
Volume = {321},
Number = {5896},
Pages = {1683-1686},
Year = {2008},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18802000},
Abstract = {Understanding cell morphogenesis during metazoan development
requires knowledge of how cells and the extracellular matrix
produce and respond to forces. We investigated how
apoptosis, which remodels tissue by eliminating
supernumerary cells, also contributes forces to a tissue
(the amnioserosa) that promotes cell-sheet fusion (dorsal
closure) in the Drosophila embryo. We showed that expression
in the amnioserosa of proteins that suppress or enhance
apoptosis slows or speeds dorsal closure, respectively.
These changes correlate with the forces produced by the
amnioserosa and the rate of seam formation between the cell
sheets (zipping), key processes that contribute to closure.
This apoptotic force is used by the embryo to drive
cell-sheet movements during development, a role not
classically attributed to apoptosis.},
Doi = {10.1126/science.1157052},
Key = {fds245901}
}
@article{fds245899,
Author = {Rodriguez-Diaz, A and Toyama, Y and Abravanel, DL and Wiemann, JM and Wells, AR and Tulu, US and Edwards, GS and Kiehart,
DP},
Title = {Actomyosin purse strings: renewable resources that make
morphogenesis robust and resilient.},
Journal = {HFSP journal},
Volume = {2},
Number = {4},
Pages = {220-237},
Year = {2008},
Month = {August},
ISSN = {1955-2068},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19404432},
Abstract = {Dorsal closure in Drosophila is a model system for cell
sheet morphogenesis and wound healing. During closure two
sheets of lateral epidermis move dorsally to close over the
amnioserosa and form a continuous epidermis. Forces from the
amnioserosa and actomyosin-rich, supracellular purse strings
at the leading edges of these lateral epidermal sheets drive
closure. Purse strings generate the largest force for
closure and occur during development and wound healing
throughout phylogeny. We use laser microsurgery to remove
some or all of the purse strings from developing embryos.
Free edges produced by surgery undergo characteristic
responses as follows. Intact cells in the free edges, which
previously had no purse string, recoil away from the
incision and rapidly assemble new, secondary purse strings.
Next, recoil slows, then pauses at a turning point.
Following a brief delay, closure resumes and is powered to
completion by the secondary purse strings. We confirm that
the assembly of the secondary purse strings requires RhoA.
We show that alpha-actinin alternates with nonmuscle myosin
II along purse strings and requires nonmuscle myosin II for
its localization. Together our data demonstrate that purse
strings are renewable resources that contribute to the
robust and resilient nature of closure.},
Doi = {10.2976/1.2955565},
Key = {fds245899}
}
@article{fds245900,
Author = {Edwards, G and Wagner, W and Sokolow, A and Pearlstein,
R},
Title = {Pressure (mechanical) effects in infrared tissue
ablation},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {6854},
Pages = {685410},
Publisher = {SPIE},
Year = {2008},
Month = {April},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.776999},
Abstract = {We experimentally demonstrate that the acoustic transients
propagating as a result Free-Electron Laser (FEL) ablation
in brain tissue exhibit a strong FEL wavelength dependence.
These acoustic transients were measured with a
time-resolved, polarization quadrature laser interferometer.
The transients are multiphased, with displacements of tens
of microns and durations of tens of milliseconds. We
calculated the Fourier transforms, power spectra, and
pressure transients based on these displacement data sets.
For 3.0 μm irradiation, the bandwidth of the Fourier
components extends to ∼20 kHz, while for 6.45 μm
irradiation the bandwidth of the Fourier components extend
to ∼8 kHz. For the 3.0 μm irradiation, the power spectra
indicate acoustic energy propagates in the bandwidth up to
∼12 kHz, with structure in the 1-4 kHz range. For the 6.45
μm radiation, the mechanical power spectra indicate the
acoustic energy propagates in the bandwidth up to ∼7 kHz,
with structure throughout. The pressure transients resulting
from 3.0 μm irradiation have a leading phase with a faster
onset, shorter duration, and more than ten times the peak
pressure compared to that observed in pressure transients
resulting from 6.45 μm irradiation. For 3.0 μm
irradiation, the observed pressure transients have peak
pressures in the MPa range and durations of ∼1 ms, while
for 6.45 μm irradiation the pressure transients have peak
pressures in the 0.1 MPa range and durations of about ∼3
ms.},
Doi = {10.1117/12.776999},
Key = {fds245900}
}
@article{fds245902,
Author = {Peralta, XG and Toyama, Y and Kiehart, DP and Edwards,
GS},
Title = {Emergent properties during dorsal closure in Drosophila
morphogenesis.},
Journal = {Physical biology},
Volume = {5},
Number = {1},
Pages = {015004},
Year = {2008},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18403825},
Abstract = {Dorsal closure is an essential stage of Drosophila
development that is a model system for research in
morphogenesis and biological physics. Dorsal closure
involves an orchestrated interplay between gene expression
and cell activities that produce shape changes, exert forces
and mediate tissue dynamics. We investigate the dynamics of
dorsal closure based on confocal microscopic measurements of
cell shortening in living embryos. During the mid-stages of
dorsal closure we find that there are fluctuations in the
width of the leading edge cells but the time-averaged
analysis of measurements indicate that there is essentially
no net shortening of cells in the bulk of the leading edge,
that contraction predominantly occurs at the canthi as part
of the process for zipping together the two leading edges of
epidermis and that the rate constant for zipping correlates
with the rate of movement of the leading edges. We
characterize emergent properties that regulate dorsal
closure, i.e., a velocity governor and the coordination and
synchronization of tissue dynamics.},
Doi = {10.1088/1478-3975/5/1/015004},
Key = {fds245902}
}
@article{fds245904,
Author = {Edwards, GS and Pearlstein, RD and Copeland, ML and Hutson, MS and Latone, K and Spiro, A and Pasmanik, G},
Title = {6450 nm wavelength tissue ablation using a nanosecond laser
based on difference frequency mixing and stimulated Raman
scattering.},
Journal = {Opt Lett},
Volume = {32},
Number = {11},
Pages = {1426-1428},
Year = {2007},
Month = {June},
ISSN = {0146-9592},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17546143},
Abstract = {A four-stage laser system was developed, emitting at a
wavelength of 6450 nm with a 3-5 ns pulse duration, < or = 2
mJ pulse energy, and 1/2 Hz pulse repetition rate. The laser
system successfully ablated rat brain tissue, where both the
collateral damage and the ablation rate compare favorably
with that previously observed with a Mark-III Free-Electron
Laser.},
Doi = {10.1364/ol.32.001426},
Key = {fds245904}
}
@article{fds245905,
Author = {Garguilo, J and Hong, L and Edwards, GS and Nemanich, RJ and Simon,
JD},
Title = {The surface oxidation potential of melanosomes measured by
free electron laser-photoelectron emission
microscopy.},
Journal = {Photochemistry and photobiology},
Volume = {83},
Number = {3},
Pages = {692-697},
Year = {2007},
Month = {May},
ISSN = {0031-8655},
url = {http://dx.doi.org/10.1562/2006-09-11-ra-1037},
Abstract = {A technique for measuring the photoionization spectrum and
the photoelectron emission threshold of a microscopic
structured material is presented. The theoretical
underpinning of the experiment and the accuracy of the
measurements are discussed. The technique is applied to
titanium silicide nanostructures and melanosomes isolated
from human hair, human and bovine retinal pigment epithelium
cells, and the ink sac of Sepia officinalis. A common
photothreshold of 4.5 +/- 0.2 eV is found for this set of
melanosomes and is attributed to the photoionization of the
eumelanin pigment. The relationship between the
photoionization threshold and the electrochemical potential
referenced to the normal hydrogen electrode is used to
quantify the surface oxidation potential of the melanosome.
The developed technique is used to examine the effect of
iron chelation on the surface oxidation potential of Sepia
melanosomes. The surface oxidation potential is insensitive
to bound Fe(III) up to saturation, suggesting that the metal
is bound to the interior of the granule. This result is
discussed in relation to the age-dependent accumulation of
iron in human melanosomes in both the eye and
brain.},
Doi = {10.1562/2006-09-11-ra-1037},
Key = {fds245905}
}
@article{fds245906,
Author = {Peralta, XG and Toyama, Y and Hutson, MS and Montague, R and Venakides,
S and Kiehart, DP and Edwards, GS},
Title = {Upregulation of forces and morphogenic asymmetries in dorsal
closure during Drosophila development.},
Journal = {Biophysical journal},
Volume = {92},
Number = {7},
Pages = {2583-2596},
Year = {2007},
Month = {April},
ISSN = {0006-3495},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17218455},
Abstract = {Tissue dynamics during dorsal closure, a stage of Drosophila
development, provide a model system for cell sheet
morphogenesis and wound healing. Dorsal closure is
characterized by complex cell sheet movements, driven by
multiple tissue specific forces, which are coordinated in
space, synchronized in time, and resilient to UV-laser
perturbations. The mechanisms responsible for these
attributes are not fully understood. We measured spatial,
kinematic, and dynamic antero-posterior asymmetries to
biophysically characterize both resiliency to laser
perturbations and failure of closure in mutant embryos and
compared them to natural asymmetries in unperturbed,
wild-type closure. We quantified and mathematically modeled
two processes that are upregulated to provide
resiliency--contractility of the amnioserosa and formation
of a seam between advancing epidermal sheets, i.e., zipping.
Both processes are spatially removed from the laser-targeted
site, indicating they are not a local response to
laser-induced wounding and suggesting mechanosensitive
and/or chemosensitive mechanisms for upregulation. In mutant
embryos, tissue junctions initially fail at the anterior end
indicating inhomogeneous mechanical stresses attributable to
head involution, another developmental process that occurs
concomitant with the end stages of closure. Asymmetries in
these mutants are reversed compared to wild-type, and
inhomogeneous stresses may cause asymmetries in wild-type
closure.},
Doi = {10.1529/biophysj.106.094110},
Key = {fds245906}
}
@article{fds245846,
Author = {Kim, Y and Gustavsson, J and Wang, P and Swift, G and Emamian, M and Hartman, S and Wallace, P and Edwards, G},
Title = {The mark-III FEL facility at duke university},
Journal = {23rd International Linear Accelerator Conference, LINAC 2006
- Proceedings},
Pages = {394-396},
Year = {2006},
Month = {December},
Abstract = {At the Free Electron Laser (FEL) Laboratory of Duke
University, there is an S-band linac based Mark III FEL
facility which can supply coherent FEL photon in the
infrared wavelength range. To supply high quality electron
beams and to have excellent pulse structure, we installed an
S-band RF gun with a Lanthanum Hexaboride (LaB6) single
crystal cathode for the Mark III FEL facility in 2005. Its
longest macropulse length is about 6 μs, and maximum
repetition rates of a macropulse and a micropulse are 15 Hz
and 2856 MHz, respectively. Therefore we can generate about
17142 bunches within a bunch train and about 257142 bunches
within one second by the S-band gun. In this paper, we
describe recent commissioning experiences of our new S-band
RF gun for the Mark III FEL facility.},
Key = {fds245846}
}
@article{fds245847,
Author = {Kim, Y and Gustavsson, J and Wang, P and Swift, G and Emamian, M and Hartman, S and Wallace, P and Edwards, G},
Title = {Commissioning of S-band RF gun and linac for the mark-III
FEL facility at Duke University},
Journal = {28th International Free Electron Laser Conference, FEL
2006},
Pages = {411-414},
Year = {2006},
Month = {December},
Abstract = {At the Free Electron Laser (FEL) Laboratory of Duke
University, there is an S-band linac based Mark III FEL
facility which can supply coherent FEL photon in the
infrared wavelength range. To supply high quality electron
beams and to have excellent pulse structure, we installed an
S-band RF gun with a Lanthanum Hexaboride (LaB6) single
crystal cathode for the Mark III FEL facility in 2005. Its
longest macropulse length is about 6 μs, and maximum
repetition rates of a macropulse and a micropulse are 15 Hz
and 2856 MHz, respectively. Therefore we can generate about
17142 bunches within a bunch train and about 257142 bunches
within one second by the S-band gun. In this paper, we
describe recent commissioning experiences of our newly
installed S-band RF gun and linac for the Mark III FEL
facility.},
Key = {fds245847}
}
@article{fds245848,
Author = {Kiehart, DP and Tokutake, Y and Chang, MS and Hutson, MS and Wiemann, J and Peralta, XG and Toyama, Y and Wells, AR and Rodriguez, A and Edwards,
GS},
Title = {Ultraviolet Laser Microbeam for Dissection of Drosophila
Embryos},
Volume = {3},
Pages = {87-103},
Booktitle = {Cell Biology: A Laboratory Handbook, 3rd
edition},
Publisher = {Elsevier},
Editor = {J.E. Celis},
Year = {2006},
Month = {December},
url = {http://dx.doi.org/10.1016/B978-012164730-8/50137-4},
Abstract = {This chapter describes the use of ultraviolet (UV) laser
microbeam interrogation strategies, combined with confocal
microscopy, to investigate the developmental process of
dorsal closure. Drosophila embryos that carry GFP-fusion
transgenes are mounted to allow high spatial and temporal
resolution imaging under conditions that allow development
to proceed unimpeded. With the help of QuickTime videos of
the time-lapsed image stacks, changes in specimen morphology
that result from laser surgical interrogation are therefore
described both qualitatively and quantitatively. Drosophila
embryos that carry GFP-fusion transgenes are mounted to
allow high spatial and temporal resolution imaging under
conditions that allow development to proceed unimpeded. For
each confocal microscope system, modifications to the
optical path of the microscope are necessary to allow
simultaneous imaging and laser surgery. The advent of
spectral variants of GFP mentioned earlier, the
proliferation of other unrelated fluorescent proteins, each
with different excitation and emission characteristics. Once
the mirrors are aligned properly to guide the unmodified
beam through the objective, the polarizer, the individual
lenses that comprise the beam expander and the telescope are
added, in that order. © 2006 Copyright © 2006 Elsevier
Inc. All rights reserved.},
Doi = {10.1016/B978-012164730-8/50137-4},
Key = {fds245848}
}
@article{fds245903,
Author = {Hong, L and Garguilo, J and Anzaldi, L and Edwards, GS and Nemanich, RJ and Simon, JD},
Title = {Age-dependent photoionization thresholds of melanosomes and
lipofuscin isolated from human retinal pigment epithelium
cells.},
Journal = {Photochemistry and photobiology},
Volume = {82},
Number = {6},
Pages = {1475-1481},
Year = {2006},
Month = {November},
ISSN = {0031-8655},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16696595},
Abstract = {Melanosomes and lipofuscin were isolated from 14-, 59-, and
76-year-old, human retinal pigment epithelium specimens and
examined. The morphological features of these samples were
studied by scanning electron microscopy and atomic force
microscopy, and the photoionization properties were examined
by photoelectron emission microscopy. Ovoid- and rod-shaped
melanosomes were observed. The size of the granules and the
distribution between the two shapes show no significant
age-dependent change. However, there is a higher occurrence
of irregularly shaped aggregates of small round granules in
older samples which suggests degradation or damage to
melanosomes occurs with age. The melanosomes from the
14-year-old donor eye are well characterized by a single
photoionization threshold, 4.1 eV, while the two older
melanosomes exhibit two thresholds around 4.4 and 3.6 eV.
Lipofuscin from both young and old cells show two
thresholds, 4.4 and 3.4 eV. The similarity of the potentials
observed for aged melanosomes and lipofuscin suggest that
the lower threshold in the melanosome sample reflects
lipofuscin deposited the surface of the melanosome. The
amount, however, is not sufficient to alter the density of
the melanosome, and therefore these granules do not separate
in a sucrose gradient at densities characteristic of the
typical melanolipofuscin granule. These data suggest that
thin deposits of lipofuscin on the surface of retinal
pigment epithelium melanosomes are common in the aged eye
and that this renders the melanosomes more
pro-oxidant.},
Doi = {10.1562/2006-03-14-ra-846},
Key = {fds245903}
}
@article{fds245907,
Author = {Bush, WD and Garguilo, J and Zucca, FA and Albertini, A and Zecca, L and Edwards, GS and Nemanich, RJ and Simon, JD},
Title = {The surface oxidation potential of human neuromelanin
reveals a spherical architecture with a pheomelanin core and
a eumelanin surface.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {103},
Number = {40},
Pages = {14785-14789},
Year = {2006},
Month = {October},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17001010},
Abstract = {Neuromelanin (NM) isolated from the substantia nigra region
of the human brain was studied by scanning probe and
photoelectron emission microscopies. Atomic force microscopy
reveals that NM granules are comprised of spherical
structures with a diameter of approximately 30 nm, similar
to that observed for Sepia cuttlefish, bovine eye, and human
eye and hair melanosomes. Photoelectron microscopy images
were collected at specific wavelengths of UV light between
248 and 413 nm, using the spontaneous-emission output from
the Duke OK-4 free electron laser. Analysis of the data
establishes a threshold photoionization potential for NM of
4.5 +/- 0.2 eV, which corresponds to an oxidation potential
of -0.1 +/- 0.2 V vs. the normal hydrogen electrode (NHE).
The oxidation potential of NM is within experimental error
of the oxidation potential measured for human eumelanosomes
(-0.2 +/- 0.2 V vs. NHE), despite the presence of a
significant fraction of the red pigment, pheomelanin, which
is characterized by a higher oxidation potential (+0.5 +/-
0.2 V vs. NHE). Published kinetic studies on the early
chemical steps of melanogenesis show that in the case of
pigments containing a mixture of pheomelanin and eumelanin,
of which NM is an example, pheomelanin formation occurs
first with eumelanin formation predominantly occurring only
after cysteine levels are depleted. Such a kinetic model
would predict a structural motif with pheomelanin at the
core and eumelanin at the surface, which is consistent with
the measured surface oxidation potential of the
approximately 30-nm constituents of NM granules.},
Doi = {10.1073/pnas.0604010103},
Key = {fds245907}
}
@article{fds245908,
Author = {Ye, T and Hong, L and Garguilo, J and Pawlak, A and Edwards, GS and Nemanich, RJ and Sarna, T and Simon, JD},
Title = {Photoionization thresholds of melanins obtained from free
electron laser-photoelectron emission microscopy,
femtosecond transient absorption spectroscopy and electron
paramagnetic resonance measurements of oxygen
photoconsumption.},
Journal = {Photochemistry and photobiology},
Volume = {82},
Number = {3},
Pages = {733-737},
Year = {2006},
Month = {May},
ISSN = {0031-8655},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16542109},
Abstract = {Free electron laser-photoelectron emission microscopy
(FEL-PEEM), femtosecond absorption spectroscopy and electron
paramagnetic resonance (EPR) measurements of oxygen
photoconsumption were used to probe the threshold potential
for ionization of eumelanosomes and pheomelanosomes isolated
from human hair. FEL-PEEM data show that both pigments are
characterized by an ionization threshold at 282 nm. However,
pheomelanosomes exhibit a second ionization threshold at 326
nm, which is interpreted to be reflective of the
benzothiazine structural motif present in pheomelanin and
absent in eumelanin. The lower ionization threshold for
pheomelanin is supported by femtosecond transient absorption
spectroscopy. Unlike photolysis at 350 nm, following
excitation of solubalized synthetic pheomelanin at 303 nm,
the transient spectrum observed between 500 and 700 nm
matches that for the solvated electron, indicating the
photoionization threshold for the solubalized pigment is
between 350 and 303 nm. For the same synthetic pheomelanin,
EPR oximetry experiments reveal an increased rate of oxygen
uptake between 338 nm and 323 nm, narrowing the threshold
for photoionization to sit between these two wavelengths.
These results on the solubalized synthetic pigment are
consistent with the FEL-PEEM results on the human
melanosomes. The lower ionization potential observed for
pheomelanin could be an important part of the explanation
for the greater incidence rate of UV-induced skin cancers in
red-haired individuals.},
Doi = {10.1562/2006-01-02-ra-762},
Key = {fds245908}
}
@article{fds245909,
Author = {Edwards, GS},
Title = {Applications of free-electron lasers to the biological and
physical sciences},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5725},
Pages = {210-219},
Publisher = {SPIE},
Year = {2005},
Month = {July},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.598150},
Abstract = {Representative examples of applications research based on
Free-Electron Lasers are reviewed. Research highlights
include: observation of absolute negative conductance in
semiconductor superlattices using a terahertz Free-Electron
Laser at the University of California, Santa Barbara;
infrared photon echos as a technique in nonlinear
spectroscopy to investigate vibrational dynamics in liquids
and glasses using an infrared Free-Electron Laser at
Stanford University; attributing the 20.1 μm stellar
spectral feature to titanium carbide clusters using an
infrared Free-Electron Laser in The Netherlands; human laser
neurosurgery and ophthalmic laser surgery using an infrared
Free-Electron Laser at Vanderbilt University; imaging of
nanoscale island dynamics during thin film growth using the
ultraviolet Free-Electron Laser at Duke University; and
nuclear resonant fluorescence measurements for parity
assignments in 138Ba using the high intensity gamma ray
source at Duke University.},
Doi = {10.1117/12.598150},
Key = {fds245909}
}
@article{fds51808,
Author = {M.S. Hutson and G.S. Edwards},
Title = {Advances in the Physical Understanding of Laser Surgery at
6.45 Microns},
Journal = {Physical Review Special Topics – Accelerator and
Beams},
Series = {Joint Accelerator Conferences Website},
Year = {2005},
Key = {fds51808}
}
@article{fds245910,
Author = {Samokhvalov, A and Hong, L and Liu, Y and Garguilo, J and Nemanich, RJ and Edwards, GS and Simon, JD},
Title = {Oxidation Potentials of Human Eumelanosomes and
Pheomelanosomes},
Journal = {Photochemistry and Photobiology},
Volume = {81},
Number = {1},
Pages = {145-148},
Year = {2005},
ISSN = {0031-8655},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15458368},
Abstract = {Eumelanosomes and pheomelanosomes isolated from black and
red human hair, respectively, were studied by photoelectron
emission microscopy (PEEM). PEEM images were collected at
various wavelengths between 207 and 344 nm, using the
spontaneous emission output of the Duke OK-4 free electron
laser (FEL). Analysis of the FEL-PEEM data revealed
ionization thresholds of 4.6 and 3.9 eV corresponding to
oxidation potentials of -0.2 and +0.5 V vs normal hydrogen
electrode for eumelanosomes and pheomelanosomes,
respectively. The difference in oxidation potential is
attributed to the pigment content of the melanosome, namely
whether it contains primarily eumelanin and pheomelanin. The
effect of added melanosomes on the reduction of
Fe(III)-cytochrome showed pheomelanosomes are stronger
reducing agents than eumelanosomes, consistent with the
measured oxidation potentials. The FEL-PEEM experiment
offers to be an important new approach for quantifying the
effects of age, oxidation and metal accumulation on the
oxidation potentials of intact melanosomes.},
Doi = {10.1562/2004-07-23-rc-245},
Key = {fds245910}
}
@article{fds245911,
Author = {Edwards, GS and Allen, SJ and Haglund, RF and Nemanich, RJ and Redlich,
B and Simon, JD and Yang, WC},
Title = {Applications of Free-Electron Lasers in the Biological and
Materials Sciences},
Journal = {Invited Review, Photochemistry and Photobiology.},
Volume = {81},
Number = {4},
Pages = {711-735},
Year = {2005},
ISSN = {0031-8655},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15755193},
Abstract = {Free-Electron Lasers (FELs) collectively operate from the
terahertz through the ultraviolet range and via intracavity
Compton backscattering into the X-ray and gamma-ray regimes.
FELs are continuously tunable and can provide optical
powers, pulse structures and polarizations that are not
matched by conventional lasers. Representative research in
the biological and biomedical sciences and condensed matter
and material research are described to illustrate the
breadth and impact of FEL applications. These include
terahertz dynamics in materials far from equilibrium,
infrared nonlinear vibrational spectroscopy to investigate
dynamical processes in condensed-phase systems, infrared
resonant-enhanced multiphoton ionization for gas-phase
spectroscopy and spectrometry, infrared matrix-assisted
laser-desorption-ionization and infrared matrix-assisted
pulsed laser evaporation for analysis and processing of
organic materials, human neurosurgery and ophthalmic surgery
using a medical infrared FEL and ultraviolet photoemission
electron microscopy for nanoscale characterization of
materials and nanoscale phenomena. The ongoing development
of ultraviolet and X-ray FELs are discussed in terms of
future opportunities for applications research.},
Doi = {10.1562/2004-11-08-ir-363},
Key = {fds245911}
}
@article{fds16425,
Author = {E.D. Jansen and M. Copeland and G.S. Edwards and W. Gabella and K. Joos and M.A. Mackanos and J.H. Shen and S.R. Uhlhorn},
Title = {Therapeutic Applications of Free-Electron
Lasers},
Booktitle = {Handbook of Laser Technology and Applications},
Publisher = {Institute of Physics Publishing},
Editor = {Colin Webb and Julian Jones},
Year = {2004},
Key = {fds16425}
}
@article{fds245924,
Author = {Samokhvalov, A and Garguilo, J and Yang, WC and Edwards, GS and Nemanich, RJ and Simon, JD},
Title = {Photoionization Threshold of Eumelanosomes Determined Using
UV Free Electron Laser-Photoelectron Emission
Microscopy},
Journal = {J. Phys. Chem. B},
Volume = {108},
Number = {42},
Pages = {16334},
Publisher = {American Chemical Society (ACS)},
Year = {2004},
ISSN = {1520-6106},
url = {http://dx.doi.org/10.1021/jp046701q},
Abstract = {The application of UV-free electron laser photoelectron
emission microscopy (UV-FEL PEEM) to measure the threshold
photoelectron spectrum and photoionization potential for
human eumelanosomes is described. The origin of potential
artifacts and the limitations of the technique are discussed
and their potential effects on the measured photoionization
potential are quantified. The UV-FEL-PEEM images collected
on human eumelanosomes isolated from black hair show that
the organelle is photoionized by UV-Bradiation. The
photoionization threshold is determined to be 4.6 ± 0.2 eV.
This result provides new insight into the origin of the
differences between the photoionization and oxygen
photoconsumption action spectra for eumelanins.},
Doi = {10.1021/jp046701q},
Key = {fds245924}
}
@article{fds245889,
Author = {Sobol, E and Sviridov, A and Kitai, M and Bagratashvili, V and Gilligan,
J and Edwards, G},
Title = {Laser-induced alterations of the Infrared light absorption
by biological tissues: Radiometric and spectroscopic
measurements},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {4829 II},
Pages = {1030-1031},
Publisher = {SPIE},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1117/12.530961},
Abstract = {The temperature alterations in the absorption coefficients
of water in cartilage and cornea under laser radiation of an
IR Free Electron Laser (PEL) were studied for several
wavelengths near 2.9 and 6.1 μm water absorption bands
using a pulsed photo-thermal radiometer (PPTR). A
computation algorithm has been modified to take into account
the real IR absorption spectra of the tissue and the
spectral sensitivity of the IR detector used. The IR
absorption spectra of cartilage and cornea have been also
measured by the FTIR spectrometer. It is shown that the
values of absorption obtined ising PPTR differ from that
obtained by the spectrometer. The limitation and possible
errors of two techniques used for have been
discussed.},
Doi = {10.1117/12.530961},
Key = {fds245889}
}
@article{fds245925,
Author = {Edwards, GS and Hutson, MS},
Title = {Advantage of the Mark-III FEL for biophysical research and
biomedical applications.},
Journal = {Journal of synchrotron radiation},
Volume = {10},
Number = {Pt 5},
Pages = {354-357},
Year = {2003},
Month = {September},
ISSN = {0909-0495},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12944619},
Abstract = {Although 6.45 micro m is not the strongest absorption band
of biological tissues in the mid-infrared, a Mark-III
free-electron laser (FEL) tuned to this wavelength can
efficiently ablate tissue while minimizing collateral
damage. A model has previously been presented that explains
this wavelength dependence as a competition between two
dynamic processes--explosive vaporization of saline and
denaturation of structural proteins. Here it is shown that
this model predicts a 'sweet-spot' for each wavelength, i.e.
a region of parameter space (incident intensity and pulse
width) in which explosive vaporization is preceded by
substantial protein denaturation. This sweet-spot is much
larger for wavelengths where protein is the dominant
chromophore. At other wavelengths, collateral damage may be
minimized within the sweet-spot, but the maximum intensities
and pulse widths in these regions are insufficient to remove
tissue at surgically relevant rates.},
Doi = {10.1107/s0909049503007970},
Key = {fds245925}
}
@article{fds245891,
Author = {Edwards, GS and Austin, RH and Carroll, FE and Copeland, ML and Couprie,
ME and Gabella, WE and Huglund, RF and Hooper, BA and Hutson, MS and Jansen, ED and Joos, KM and Kiehart, DP and Lindau, I and Miao, J and Pratisto, HS and Shen, JH and Tokutake, Y and Van der Meer and AFG and Xie,
A},
Title = {Free-electron-laser-based biophysical and biomedical
instrumentation},
Journal = {Review of Scientific Instruments},
Volume = {74},
Number = {7},
Pages = {3207-3245},
Publisher = {AIP Publishing},
Year = {2003},
Month = {July},
url = {http://dx.doi.org/10.1063/1.1584078},
Abstract = {A survey of biophysical and biomedical applications of
free-electron lasers (FEL) was discussed. It was found that
the midinfrared SCA FEL and UV FELs based on storage rings
were useful for one- and two-color spectroscopic
investigations of biophysical proesses. The light source
capabilities of FEL which include combinations of wavelength
ranges and pulse structures were also elaborated.},
Doi = {10.1063/1.1584078},
Key = {fds245891}
}
@article{fds245928,
Author = {Sobol, EN and Sviridov, AP and Kitai, MS and Edwards,
GS},
Title = {Temperature alterations of infrared light absorption by
cartilage and cornea under free-electron laser
radiation.},
Journal = {Applied optics},
Volume = {42},
Number = {13},
Pages = {2443-2449},
Year = {2003},
Month = {May},
ISSN = {0003-6935},
url = {http://dx.doi.org/10.1364/ao.42.002443},
Abstract = {Like pure water, the water incorporated into cartilage and
cornea tissue shows a pronounced dependence of the
absorption coefficient on temperature. Alteration of the
temperature by radiation with an IR free-electron laser was
studied by use of a pulsed photothermal radiometric
technique. A computation algorithm was modified to take into
account the real IR absorption spectra of the tissue and the
spectral sensitivity of the IR detector used. The absorption
coefficients for several wavelengths within the 2.9- and
6.1-microm water absorption bands have been determined for
various laser pulse energies. It is shown that the
absorption coefficient for cartilage decreases at
temperatures higher than 50 degrees C owing to thermal
alterations of water-water and water-biopolymer
interactions.},
Doi = {10.1364/ao.42.002443},
Key = {fds245928}
}
@article{fds245926,
Author = {Hutson, MS and Tokutake, Y and Chang, M-S and Bloor, JW and Venakides,
S and Kiehart, DP and Edwards, GS},
Title = {Forces for morphogenesis investigated with laser
microsurgery and quantitative modeling.},
Journal = {Science (New York, N.Y.)},
Volume = {300},
Number = {5616},
Pages = {145-149},
Year = {2003},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12574496},
Abstract = {We investigated the forces that connect the genetic program
of development to morphogenesis in Drosophila. We focused on
dorsal closure, a powerful model system for development and
wound healing. We found that the bulk of progress toward
closure is driven by contractility in supracellular "purse
strings" and in the amnioserosa, whereas adhesion-mediated
zipping coordinates the forces produced by the purse strings
and is essential only for the end stages. We applied
quantitative modeling to show that these forces, generated
in distinct cells, are coordinated in space and synchronized
in time. Modeling of wild-type and mutant phenotypes is
predictive; although closure in myospheroid mutants
ultimately fails when the cell sheets rip themselves apart,
our analysis indicates that beta(PS) integrin has an
earlier, important role in zipping.},
Doi = {10.1126/science.1079552},
Key = {fds245926}
}
@article{fds304533,
Author = {Sobol, E and Sviridov, A and Kitai, M and Gilligan, JM and Tolk, NH and Edwards, GS},
Title = {Time-resolved, light scattering measurements of cartilage
and cornea denaturation due to free electron laser
radiation.},
Journal = {Journal of biomedical optics},
Volume = {8},
Number = {2},
Pages = {216-222},
Year = {2003},
Month = {April},
url = {http://dx.doi.org/10.1117/1.1559996},
Abstract = {Light scattering is used to monitor the dynamics and energy
thresholds of laser-induced structural alterations in
biopolymers due to irradiation by a free electron laser
(FEL) in the infrared (IR) wavelength range 2.2 to 8.5
microm. Attenuated total reflectance (ATR) Fourier-transform
IR (FTIR) spectroscopy is used to examine infrared tissue
absorption spectra before and after irradiation. Light
scattering by bovine and porcine cartilage and cornea
samples is measured in real time during FEL irradiation
using a 650-nm diode laser and a diode photoarray with time
resolution of 10 ms. The data on the time dependence of
light scattering in the tissue are modeled to estimate the
approximate values of kinetic parameters for denaturation as
functions of laser wavelength and radiant exposure. We found
that the denaturation threshold is slightly lower for cornea
than for cartilage, and both depend on laser wavelength. An
inverse correlation between denaturation thresholds and the
absorption spectrum of the tissue is observed for many
wavelengths; however, for wavelengths near 3 and 6 microm,
the denaturation threshold does not exhibit the inverse
correlation, instead being governed by heating kinetics of
tissue. It is shown that light scattering is useful for
measuring the denaturation thresholds and dynamics for
different biotissues, except where the initial absorptivity
is very high.},
Doi = {10.1117/1.1559996},
Key = {fds304533}
}
@article{fds245927,
Author = {Edwards, GS and Austin, RH and Carroll, FE and Copeland, ML and Couprie,
ME and Gabella, WE and Haglund, RF and Hooper, BA and Hutson, MS and Jansen, ED and Joos, KM and Kiehart, DP and Lindau, I and Miao, J and Pratisto, HS and Shen, JH and Tokutake, Y and van Der Meer and L and Xie,
A},
Title = {FEL-based biophysical and biomedical instrumentation},
Journal = {Invited paper, Review of Scientific Instruments},
Volume = {74},
Number = {7},
Pages = {3207-3245},
Year = {2003},
Key = {fds245927}
}
@article{fds245929,
Author = {Sobol, E and Sviridov, A and Kitai, M and Gilligan, J and Tolk, N and Edwards, G},
Title = {Time-resolved, light scattering measurements of cartilage
and cornea denaturation due to FEL radiation: effect of
infrared wavelength},
Journal = {Journal of Biomedical Optics},
Volume = {8},
Number = {2},
Pages = {216-222},
Year = {2003},
Month = {Spring},
url = {http://dx.doi.org/10.1117/1.1559996},
Abstract = {Light scattering is used to monitor the dynamics and energy
thresholds of laser-induced structural alterations in
biopolymers due to irradiation by a free electron laser
(FEL) in the infrared (IR) wavelength range 2.2 to 8.5
μm. Attenuated total reflectance (ATR) Fourier-transform
IR (FTIR) spectroscopy is used to examine infrared tissue
absorption spectra before and after irradiation. Light
scattering by bovine and porcine cartilage and cornea
samples is measured in real time during FEL irradiation
using a 650-nm diode laser and a diode photoarray with time
resolution of 10 ms. The data on the time dependence of
light scattering in the tissue are modeled to estimate the
approximate values of kinetic parameters for denaturation as
functions of laser wavelength and radiant exposure. We found
that the denaturation threshold is slightly lower for cornea
than for cartilage, and both depend on laser wavelength. An
inverse correlation between denaturation thresholds and the
absorption spectrum of the tissue is observed for many
wavelengths; however, for wavelengths near 3 and 6 μm,
the denaturation threshold does not exhibit the inverse
correlation, instead being governed by heating kinetics of
tissue. It is shown that light scattering is useful for
measuring the denaturation thresholds and dynamics for
different biotissues, except where the initial absorptivity
is very high.},
Doi = {10.1117/1.1559996},
Key = {fds245929}
}
@article{fds245934,
Author = {Hutson, MS and Hauger, SA and Edwards, G},
Title = {Thermal diffusion and chemical kinetics in laminar
biomaterial due to heating by a free-electron
laser.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {65},
Number = {6 Pt 1},
Pages = {061906},
Year = {2002},
Month = {June},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/physreve.65.061906},
Abstract = {We have theoretically investigated the role of thermal
diffusion and chemical kinetics as a possible dynamic
explanation for the preferential ablative properties of
infrared radiation from a free-electron laser (FEL). The
model is based on a laminar system composed of alternating
layers of protein and saline. We have compared exposure to 3
microm where water is the main absorber and 6.45 microm
where both water and protein absorb. The picosecond pulses
of the superpulse are treated as a train of impulses. We
find that the heating rates are sufficient to superheat the
outer saline layers on the nanosecond time scale, leading to
explosive vaporization. We also find that competition
between the layer-specific heating rates and thermal
diffusion results in a wavelength-dependent separation in
layer temperatures. We consider the onset of both chemical
bond breaking and the helix-coil transition of protein prior
to vaporization in terms of the thermal, chemical, and
structural properties of the system as well as laser
wavelength and pulse structure. There is no evidence for
thermal bond breaking on these time scales. At 6.45 microm,
but not 3 microm, there is evidence for a significant
helix-coil transition. While the native protein is ductile,
the denatured protein exhibits brittle fracture. This model
provides a dynamic mechanism to account for the preferential
ablative properties observed with FEL radiation tuned near
6.45 microm.},
Doi = {10.1103/physreve.65.061906},
Key = {fds245934}
}
@article{fds245935,
Author = {Hutson, MS and Palmer, RA and Chang, MS and Gillikin, A and Litvinenko,
V and Edwards, G},
Title = {Commissioning of a UV/time-resolved-FTIR beamline at the
Duke FEL laboratory},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {483},
Number = {1-2},
Pages = {560-564},
Publisher = {Elsevier BV},
Year = {2002},
Month = {May},
ISSN = {0168-9002},
url = {http://dx.doi.org/10.1016/S0168-9002(02)00382-0},
Abstract = {We describe the commissioning of a novel two-color beamline
at the Duke Free Electron Laser Laboratory, designed to
perform time-resolved FTIR spectroscopy in a pump-probe
scheme with sub-nanosecond resolution to measure dynamical
processes with durations as long as 10 ns. The UV pump
pulses are produced by the tunable (193-700 nm) output of
the OK-4 Storage-Ring FEL. The broadband, infrared probe
pulses are generated as synchrotron radiation in a bending
magnet downstream of the OK-4 wiggler. The repetition rate
of the light source (2.79 MHz) is ideal for operating the
interferometer in the rapid-scan, asynchronous sampling
mode. An investigation of DNA photolyase is proposed. ©
2002 Elsevier Science B.V. All rights reserved.},
Doi = {10.1016/S0168-9002(02)00382-0},
Key = {fds245935}
}
@article{fds245885,
Author = {Hutson, MS and Palmer, RA and Gillikin, A and Chang, MS and Litvinenko,
VN and Edwards, GS},
Title = {UV/time-resolved FTIR beamline at the Duke FEL
Laboratory},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {4633},
Series = {Proceedings of the SPIE},
Pages = {225-232},
Booktitle = {Commercial and Biomedical Applications of Ultrafast and Free
Electron Lasers},
Publisher = {SPIE},
Editor = {Glenn S. Edwards and Joseph Neev and Andreas Ostendorf and John
Sutherland},
Year = {2002},
Month = {January},
url = {http://dx.doi.org/10.1117/12.461383},
Abstract = {We describe the commissioning of a novel two-color beamline
at the Duke Free Electron Laser Laboratory, designed to
perform time-resolved FTIR spectroscopy in a pump-probe
scheme with sub-nanosecond resolution to measure dynamical
processes with durations as long as ten nanoseconds. The UV
pump pulses are produced by the tunable (193 to 700 nm)
output of the OK-4 Storage-Ring FEL. The broadband, infrared
probe pulses are generated as synchrotron radiation in a
bending magnet downstream of the OK-4 wiggler. The
repetition rate of the light source (2.79 MHz) is ideal for
operating the interferometer in the rapid-scan, asynchronous
sampling mode.},
Doi = {10.1117/12.461383},
Key = {fds245885}
}
@article{fds245886,
Author = {Edwards, G and Shane Hutson and M and Hauger, S and Kozub, J and Shen, J and Shieh, C and Topadze, K and Joos, K},
Title = {Comparison of OPA and Mark-III FEL for tissue ablation at
6.45 microns},
Journal = {Proceedings of SPIE-The International Society for Optical
Engineering},
Volume = {4633},
Pages = {194-200},
Booktitle = {Commercial and Biomedical Applications of Ultrafast and Free
Electron Lasers},
Publisher = {SPIE},
Editor = {Glenn S. Edwards and Joseph Neev and Andreas Ostendorf and John
Sutherland},
Year = {2002},
Month = {January},
url = {http://dx.doi.org/10.1117/12.461379},
Abstract = {We have investigated the experimental consequences of two
picosecond infrared lasers, both tuned to 6.45 μm and
focused on ocular tissue. The exposure conditions were
comparable, other than pulse repetition rate, where an
optical parametric oscillator/amplifier laser (OPA) system
operates at a kilohertz and the Mark-III FEL at 3 gigahertz.
In both cases, the peak intensity was near 2×1014 W/m2 and
the total delivered energy was approximately 125 mJ. The
Mark-III consistently ablates tissue, while the OPA fails to
ablate or to damage corneal tissue. In particular, there is
no experimental evidence for protein denaturation due to OPA
irradiation. We account for these observations in terms of a
theoretical model based on thermal diffusion and threshold
conditions for superheating and chemical kinetics. We
comment on the relevance of tissue geometry.},
Doi = {10.1117/12.461379},
Key = {fds245886}
}
@article{fds245887,
Author = {Edwards, GS and Neev, J and Ostendorf, A and Sutherland,
JC},
Title = {Erratum: (Commercial and Biomedical Applications of
Ultrafast and Free-Electron Lasers (23-24 January
2002))},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {4633},
Pages = {243-244},
Year = {2002},
Month = {January},
Key = {fds245887}
}
@article{fds245888,
Author = {Edwards, GS and Shane Hutson and M and Hauger, S},
Title = {Heat diffusion and chemical kinetics in Mark-III FEL tissue
ablation},
Journal = {Proceedings of SPIE-The International Society for Optical
Engineering},
Volume = {4633},
Pages = {184-193},
Booktitle = {Commercial and Biomedical Applications of Ultrafast and Free
Electron Lasers},
Publisher = {SPIE},
Editor = {Glenn S. Edwards and Joseph Neev and Andreas Ostendorf and John
Sutherland},
Year = {2002},
Month = {January},
url = {http://dx.doi.org/10.1117/12.461378},
Abstract = {We present in some detail a theoretical model that provides
a dynamical account for the experimentally observed ablative
properties of an FEL tuned near 6.45 microns. The model is
based on thermal diffusion and chemical kinetics in a system
of alternating layers of protein and saline as heated by an
infrared Mark-III FEL. We compare exposure at 3.0 microns,
where water is the sole absorber, to that at 6.45 microns,
where both protein and water absorb. The picosecond pulses
of the Mark-III superpulse are treated as a train of
impulses. We consider the onset of both the helix-coil
transition and chemical bond breaking in terms of the
thermal, chemical, and mechanical properties of the system
as well as laser wavelength and pulse structure.},
Doi = {10.1117/12.461378},
Key = {fds245888}
}
@article{fds245882,
Author = {Pinayev, I and Emamian, M and Gustavsson, J and Litvinenko, VN and Morcombe, P and Oakeley, O and Rathbone, V and Swift, G and Wang, P and Edwards, G},
Title = {Status of Mark III FEL},
Journal = {Proceedings of the IEEE Particle Accelerator
Conference},
Volume = {4},
Pages = {2725-2726},
Year = {2001},
Month = {December},
Abstract = {Status of Mark III free electron laser and its upgrades were
presented. An old high voltage source utilizing unregulated
rectifier was replaced with power supplies manufactured by
Maxwell to reduce optical power fluctuations. To implement
faster change of lasing wavelength a fixed coupler was
replaced with a variable power splitter equipped with remote
control. Upgradation significantly increased the performance
of Mark III FEL and brought it up with up-to-date
technology.},
Key = {fds245882}
}
@article{fds245884,
Author = {Wang, P and Litvinenko, V and Emamian, M and Faircloth, J and Gustavsson, J and Hartman, S and Mikhailov, S and Morcombe, P and Oakeley, O and Patterson, J and Pentico, M and Pinayev, I and Shevchenko, O and Swift, G and Edwards, G},
Title = {Status report on the Duke FEL facility},
Journal = {Proceedings of the IEEE Particle Accelerator
Conference},
Volume = {4},
Pages = {2819-2820},
Year = {2001},
Month = {December},
Abstract = {At the Duke Free Electron Laser (FEL) Laboratory, there are
two FEL machines: the Mark III infrared FEL and the
OK-4/Storage Ring, which produces UV and XUV laser beam as
well as gamma rays via Compton backscattering. The recent
status of Mark-III machine is described in another paper.
Here we will concentrate on the new development of the
OK-4/Storage Ring FEL and its performance and capabilities.
A brief history of this machine and the future plan are also
given in this paper.},
Key = {fds245884}
}
@article{fds245931,
Author = {Shen, JH and Harrington, JA and Edwards, GS and Joos,
KM},
Title = {Hollow-glass waveguide delivery of an infrared free-electron
laser for microsurgical applications.},
Journal = {Applied optics},
Volume = {40},
Number = {4},
Pages = {583-587},
Year = {2001},
Month = {February},
ISSN = {0003-6935},
url = {http://dx.doi.org/10.1364/ao.40.000583},
Abstract = {The purpose of this research is to deliver
free-electron-laser (FEL) pulses for intraocular
microsurgery. The FEL at Vanderbilt University is tunable
from 1.8 to 10.8 microm. To deliver the FEL beam we used a
metallic-coated hollow-glass waveguide of 530-mum inner
diameter. A 20-gauge cannula with a miniature CaF2 window
shielded the waveguide from water. Open-sky retinotomy was
performed on cadaver eyes. The system delivered as much as 6
x 10(5) W of FEL peak power to the intraocular tissues
without damage to the waveguide or to the surgical
probe.},
Doi = {10.1364/ao.40.000583},
Key = {fds245931}
}
@article{fds3886,
Author = {E.J. Swift, Jr. and G.S. Edwards and J. Perdigao and J.Y. Thompson and M.F. Nunes and D.E. Ruddell and A. Negishi},
Title = {Free-electron laser etching of dental enamel},
Journal = {Journal of Dentistry},
Volume = {29},
Pages = {347-353},
Year = {2001},
Month = {January},
Key = {fds3886}
}
@article{fds245930,
Author = {Swift Jr and EJ and Edwards, GS and Perdigao, J and Thompson, JY and F>Nunes, M and Ruddell, DE and Negishi, A},
Title = {Free-electron laser etching of dental enamel},
Journal = {Journal of Dentistry},
Volume = {29},
Number = {5},
Pages = {347-353},
Year = {2001},
url = {http://dx.doi.org/10.1016/s0300-5712(01)00019-7},
Abstract = {<h4>Objective</h4>The purpose of this study was to evaluate
the Mark-III free-electron laser as a means of etching
enamel surfaces, with potential application to resin
bonding.<h4>Methods</h4>The FEL was tuned to wavelengths
ranging from 3.0 to 9.2 microm. Specific wavelengths that
are resonantly absorbed by phosphates, proteins, and water
were used. First, bovine enamel was polished and exposed to
static FEL exposures. Lased enamel was examined using
scanning electron microscopy (SEM). Additional bovine enamel
specimens were exposed to FEL at similar wavelengths, but
with rastering to create treated rectangular areas on each
specimen. Surface roughness was evaluated using profilometry
and atomic force microscopy (AFM). Composite was bonded to
the lased enamel, and shear bond strengths were determined
using an Instron universal testing machine. As a control,
the surface roughness of, and shear bond strengths to,
acid-etched enamel were determined.<h4>Results</h4>Static
FEL exposures caused changes in the enamel ranging from an
etched appearance to pits, cracks, and frank cratering. The
surface roughness of lased enamel was much greater than that
of acid-etched enamel, and was qualitatively different as
well. Shear bond strengths of resin to acid-etched enamel
were significantly higher than bond strengths to lased
enamel.<h4>Conclusions</h4>Under the conditions used in this
study, the FEL did not offer a practical and effective
method of etching enamel for resin bonding. However, the
ability of the FEL to deliver many specific wavelengths
makes it an interesting tool for further research of laser
effects on tooth structure.},
Doi = {10.1016/s0300-5712(01)00019-7},
Key = {fds245930}
}
@article{fds3882,
Author = {E.N. Sobol and A.P. Sviridov and M.S. Kitai and J. Gilligan and G.S.
Edwards},
Title = {Alterations of absorption coefficient of tissue water as a
result of the heating under the IR FEL radiation with
different wavelengths},
Journal = {International Biomedical Optics Symposium,
SPIE},
Volume = {3925},
Pages = {78},
Year = {2000},
Month = {January},
Key = {fds3882}
}
@article{fds245881,
Author = {Edwards, G and Fowler, C and Hutson, S and Litvinenko, V and Palmer, R and Roberts, B},
Title = {Light source capabilities and applications research at the
Duke FEL laboratory},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3925},
Pages = {106-116},
Editor = {Glenn S. Edwards and John C. Sutherland},
Year = {2000},
Month = {January},
Abstract = {The Duke FEL Laboratory is a national and international
users facility. We describe the current light source
capabilities in the infrared, visible, ultraviolet, and
Gamma rays. Plans are summarized for the development of two
novel beamlines, one for UV-resonant Raman spectroscopy and
the other an essentially jitter-free UV-pump, IR-probe
'two-color' source with rapid-scan FTIR time-resolved
detection of the broadband infrared. Current applications
research is summarized, with a more detailed description of
research in corneal would healing.},
Key = {fds245881}
}
@article{fds245883,
Author = {Sobol, E and Sviridov, A and Kitai, M and Gilligan, J and Edwards,
G},
Title = {Alterations of absorption coefficients of tissue water as a
result of the heating under the IR FEL radiation with
different wavelengths},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3925},
Pages = {78-88},
Year = {2000},
Month = {January},
Abstract = {The effect of temperature dependent shift of water
absorption band, known for pure water, has been examined,
for the first time, for tissue water, using the IR Free
Electron Laser radiation. Cooling kinetics of cartilage and
cornea irradiated was measured with a fluorimeter. We have
modified the computation algorithm to calculate the optical
properties from these measurements more precisely.
Temperature dependence of the absorption coefficient of
tissue water is studied, for both sides of water absorption
bands at 3.0 and 6.1 μm. It is shown that cooling kinetics
for samples irradiated with small laser intensity is the
same, for both wavelengths of each pair: 6.2 and 6.0; 6.35
and 5.92; 3.22 and 2.81; 3.15 and 2.87 μm. For high laser
intensity, the cooling curves are differ, for above
wavelengths. From cooling kinetics curves we have calculated
the values of absorption coefficient and their alterations
for above wavelengths. We have modified the computation
algorithm taking into account the real FTIR spectra of the
tissue, the effect of water evaporation from the tissue, and
specific characteristics of the IR detector used. It is
shown that absorption coefficient may increase or decrease
depending on laser wavelength and fluence, and that the
water absorption bands have a tendency to shift under laser
heating. The IR absorption spectra of cartilage and cornea
have been measured by the FTIR spectrometer. The limitation
and possible errors of two techniques used have been
discussed.},
Key = {fds245883}
}
@article{fds245880,
Author = {Palmer, RA and Smith, GD and Litvinenko, VN and Edwards,
G},
Title = {Fourier transform infrared picosecond time-resolved
spectroscopy with a UV free electron laser pump and
synchrotron IR probe},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3775},
Pages = {137-144},
Publisher = {SPIE},
Year = {1999},
Month = {December},
url = {http://dx.doi.org/10.1117/12.366638},
Abstract = {The development of the capability for sub-nanosecond
time-resolved infrared spectroscopy, combining the broad
spectral bandwidth and other well-established advantages of
Fourier transform interferometry with the high power, high
repetition rate and wide tunability of an electron storage
ring-based UV free-electron laser pump, along with the
broadband, pulsed, featureless IR continuum of synchrotron
radiation from the same storage ring as a probe, is
described. The capabilities of the system compared to other
alternatives for fast, time-resolved infrared spectroscopy
are discussed.},
Doi = {10.1117/12.366638},
Key = {fds245880}
}
@article{fds245879,
Author = {Sobol, E and Sviridov, A and Kitai, M and Gilligan, J and Tolk, NH and Edwards, G},
Title = {Effect of wavelength on threshold and kinetics of tissue
denaturation under laser radiation},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3601},
Pages = {122-129},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1117/12.349995},
Abstract = {We consider the denaturation process as an alteration in
ordered organization of tissue structure and study the
threshold and kinetics of laser-induced denaturation in
cartilage and cornea undergoing irradiation from a free
electron laser (FEL) in the wavelength range 2.2-8.5 μ.
Light-scattering by cartilage samples was measured in
real-time during FEL irradiation using a 630-nm diode laser
and a diode array with time resolution of 10 ms. We found
that denaturation threshold is slightly lower than that for
cartilage, and both depend on laser wavelength. A strong
inverse correlation between denaturation thresholds and the
absorption spectrum of the tissue is observed. Only for the
wavelength region near the 3 μ water absorption band was
the denaturation threshold not inversely proportional to the
absorption coefficient. We believe this was because the
radiation penetration depth was very small in this
high-absorption region, so tissue denaturation occurred only
in a layer too thin to produce significant light scattering.
ATR spectra of 2.4 mm thick cartilage samples was measured
before and after irradiation at 6.0 and 2.2 μ. At 6.0 μ,
where the absorption is high, the spectrum of the irradiated
(front) surface showed changes, while the spectrum of the
back surface was identical to that before irradiation. This
difference results from dramatic denaturation (with chemical
bond breaking) at the front surface due to laser heating in
a small absorption depth. For 2.2 μ irradiation, where the
absorption is small, the spectra of the front and back of
the irradiated sample were unchanged from before
irradiation, wile light scattering alteration shown the
denaturation process began, for laser fluences above the
denaturation threshold. This indicates that the absorption
is too small to produce deep denaturation of the tissue with
dramatic alteration of structure. Thus, we have shown that
light scattering is useful for measuring denaturation
thresholds and kinetics for biotissues except where the
initial absorptivity is very high.},
Doi = {10.1117/12.349995},
Key = {fds245879}
}
@article{fds245932,
Author = {Keay, B and Mendenhall, M and Edwards, G},
Title = {Time-resolved infrared transmittance and reflectance of a
propagating melt in gaas},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {60},
Number = {15},
Pages = {10898-10902},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevB.60.10898},
Abstract = {The time-resolved infrared transmittance and reflectance of
a melt induced by a 10 nsec optical-laser pulse has been
observed in an undoped crystalline GaAs wafer. Picosecond
pulsed, 2.86 GHz repetition rate, infrared radiation from a
free-electron laser was used to study the formation and
propagation of the melt in real time. The back reflectance
(probed from the side opposite to the incident optical
radiation) displays interference oscillations as the melt
propagates in the sample. The measurements are in agreement
with model calculations which describe the melt with the
Drude free-carrier model. © 1999 The American Physical
Society.},
Doi = {10.1103/PhysRevB.60.10898},
Key = {fds245932}
}
@article{fds245878,
Author = {Shen, JH and Joos, KM and Harrington, JA and O'Day, DM and Edwards,
GS},
Title = {Hollow waveguide delivered infrared free electron laser for
microsurgical applications},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3262},
Pages = {130-134},
Publisher = {SPIE},
Year = {1998},
Month = {December},
url = {http://dx.doi.org/10.1117/12.309466},
Abstract = {The Free Electron Laser (FEL) at Vanderbilt University is
tunable from 2 μm to 9 μm in the mid-infrared spectrum,
which is capable of controlling predicted laser-tissue
interaction by selecting a specific wavelength. However,
delivery of this laser into the internal portion of the eye
is difficult because of strong water absorption at this
spectrum range and the high peak power of the FEL. We used a
metallic coated hollow waveguide with a 530 μm inner
diameter and 1 meter in length, and delivered the FEL beam
to an autoclaved surgical probe. The probe tip was an 18
gauge canula with a mini CaF2 window fixed in front of it to
protect the waveguide from contacting water. Human and
animal cadaver eyes were used to perform an open sky retinal
cutting procedure. The system was able to deliver 60% of FEL
energy to the intraocular tissues. Up to 6×105 w peak power
was reached without damage to the waveguide or the surgical
probe at the spectrum range of 2.94 μm to 7.7 μm. In
conclusion, the hollow waveguide is suitable for delivering
the infrared FEL for intraocular microsurgical
procedures.},
Doi = {10.1117/12.309466},
Key = {fds245878}
}
@article{fds245933,
Author = {Edwards, G and Engh, D and Kozub, J and Williams,
R},
Title = {Infrared dynamics of collagen, microtubules, and water:
Biophysical research enabling biomedical FEL
applications},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
B: Beam Interactions with Materials and Atoms},
Volume = {144},
Number = {1-4},
Pages = {260-264},
Publisher = {Elsevier BV},
Year = {1998},
Month = {September},
url = {http://dx.doi.org/10.1016/S0168-583X(98)00313-9},
Abstract = {Experimental evidence is presented for FEL induced
photothermal protein chemistry and FEL modulation of
microtubule dynamics. These findings are discussed in terms
of previous investigations of FEL tissue ablation to explore
the importance of the micropulse structure of the Mark-III
FEL. We propose various roles for localized heating in FEL
modulation of the dynamics of biological macromolecules.
Potential medical applications are described. © 1998
Published by Elsevier Science B.V. All rights
reserved.},
Doi = {10.1016/S0168-583X(98)00313-9},
Key = {fds245933}
}
@article{fds245873,
Author = {Shen, JH and Joos, KM and Shetlar, DJ and Robinson, RD and Thind, GK and Edwards, GS and O'Day, DM},
Title = {Cultured human cornea healing process after free electron
laser ablation},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2971},
Pages = {83-88},
Publisher = {SPIE},
Year = {1997},
Month = {December},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.275106},
Abstract = {The purpose of this study is to investigate the healing
process in cultured human cornea after infrared Free
Electron Laser ablation. Fresh human cadaver cornea was
ablated using the Free Electron Laser at the amide II band
peak (6.45 micrometers). The cornea was then cultured in an
incubator for 18 days. Haze development within the ablated
area was monitored during culture. Histologic sections of
the cornea showed complete re-epithelialization of the lased
area, and ablation of the underlying Bowman's layer and
stroma. The endothelium appeared unaffected. Cultured human
corneas may provide useful information regarding the healing
process following laser ablation. ©2004 Copyright SPIE -
The International Society for Optical Engineering.},
Doi = {10.1117/12.275106},
Key = {fds245873}
}
@article{fds245874,
Author = {Edwards, G},
Title = {10. Physical Mechanisms Governing the Ablation of Biological
Tissue},
Journal = {Experimental Methods in the Physical Sciences},
Volume = {30},
Number = {C},
Pages = {449-473},
Publisher = {Elsevier},
Year = {1997},
Month = {December},
ISSN = {1079-4042},
url = {http://dx.doi.org/10.1016/S0076-695X(08)60402-0},
Doi = {10.1016/S0076-695X(08)60402-0},
Key = {fds245874}
}
@article{fds245877,
Author = {Wagner, K and Keyes, E and Kephart, TW and Edwards,
G},
Title = {Analytical Debye-Huckel model for electrostatic potentials
around dissolved DNA.},
Journal = {Biophysical journal},
Volume = {73},
Number = {1},
Pages = {21-30},
Year = {1997},
Month = {July},
ISSN = {0006-3495},
url = {http://dx.doi.org/10.1016/s0006-3495(97)78043-3},
Abstract = {We present an analytical, Green-function-based model for the
electric potential of DNA in solution, treating the
surrounding solvent with the Debye-Huckel approximation. The
partial charge of each atom is accounted for by modeling DNA
as linear distributions of atoms on concentric cylindrical
surfaces. The condensed ions of the solvent are treated with
the Debye-Huckel approximation. The resultant leading term
of the potential is that of a continuous shielded line
charge, and the higher order terms account for the helical
structure. Within several angstroms of the surface there is
sufficient information in the electric potential to
distinguish features and symmetries of DNA. Plots of the
potential and equipotential surfaces, dominated by the
phosphate charges, reflect the structural differences
between the A, B, and Z conformations and, to a smaller
extent, the difference between base sequences. As the
distances from the helices increase, the magnitudes of the
potentials decrease. However, the bases and sugars account
for a larger fraction of the double helix potential with
increasing distance. We have found that when the solvent is
treated with the Debye-Huckel approximation, the potential
decays more rapidly in every direction from the surface than
it did in the concentric dielectric cylinder
approximation.},
Doi = {10.1016/s0006-3495(97)78043-3},
Key = {fds245877}
}
@booklet{Shen97,
Author = {Shen, JH and Loos, KJ and Shetlar, DJ and Robinson, RD and Oday, DM and Edwards, GS},
Title = {Investigation of a clinical intraocular microsurgical device
using the infrared free electron laser},
Journal = {Investigative Ophthalmology \& Visual Science},
Volume = {38},
Number = {4},
Pages = {418-418},
Year = {1997},
Month = {March},
ISSN = {0146-0404},
Abstract = {Purpose. The Free Electron Laser (PEL) has a wavelength
tunability range between 2 and 9 m in the mid-infrared
spectrum. It is capable of producing controlled predictable
laser-tissue interactions by selecting specific wavelengths.
However, delivery of this laser into the internal portion of
the eye is difficult because of strong water absorption in
this spectrum and the high peak power of the PEL. We
investigated the feasibility of a hollow waveguide
microsurgical device for FEL intraocular delivery Methods.
The infrared FEL beam was coupled into a metalliccoated
hollow waveguide (530 u,m inner diameter, l m length) and
transmitted to an autoclaved surgical probe. The probe tip
was an 18 gauge cannula fitted with a miniCaF2 window to
protect the waveguide. Retinal tissues in human and animal
cadaver eyes were incised at wavelengths of 2.94, 3.8, and
6.45 u.m. Results. Up to 6xl05 W peak power was delivered to
the intraocular tissues to successfully incise the retinas.
The system was able to deliver 60% of the FEL energy
.without damage to the waveguide or the surgical probe.
Conclusions. The hollow waveguide delivery system allows use
of the infrared FEL for intraocular microsurgical
use.},
Key = {Shen97}
}
@booklet{Robinson97,
Author = {Robinson, RD and Shen, JH and Joos, KM and Shetlar, DJ and Edwards, GS and Oday, DM},
Title = {Healing of cultured human cornea after free electron laser
ablation},
Journal = {Investigative Ophthalmology \& Visual Science},
Volume = {38},
Number = {4},
Pages = {1916-1916},
Year = {1997},
Month = {March},
ISSN = {0146-0404},
Abstract = {Purpose. To study the healing process in cultured human
corneas after Qswitched Er:YAG laser ablation. Methods.
Fresh human cadaver corneas within were ablated with a
Q-switched Er:YAG laser at 2.94 m wavelength. (100ns, 1 Hz)
The radiant exposure was 500 mJ/cm2. A focal crater was
created using between 60 and 80 pulses. A linear incision
was also formed by slowly scanning the laser over the
corneal surface. Each cornea was cultured on a tissue
supporting frame immediately after the ablation. Culture
media consisted of 92% minimum essential media, 8% fetal
bovine serum, 0.125% HEPES buffer solution, 0.125%
gentamicin, and 0.05% fungizone. The entire tissue frame and
media container were kept in an incubator at 37°C and 5%
C02. Serial macroscopic photographs of the cultured corneas
were taken during the healing process. Histology was
performed after 17 days of culture. Results. At 3 days, a
transient haze was observed within the craters which then
resolved between 7 and 14 days. No haze was seen along the
linear incision. Histologie sections of the cornea showed
complete re-epithelialization of the lased area. The
endothelium appeared unaffected. Conclusions. Cultured human
corneas may provide useful information regarding the healing
process following laser ablation.},
Key = {Robinson97}
}
@article{fds245870,
Author = {Shen, JH and Joos, KJ and O'Day, DM and Edwards, GS},
Title = {Investigation of clinical internal microsurgical device with
use of hollow waveguide delivered infrared free electron
laser},
Journal = {Conference Proceedings - Lasers and Electro-Optics Society
Annual Meeting-LEOS},
Volume = {11},
Pages = {151-152},
Year = {1997},
Month = {January},
Abstract = {An application of hollow waveguide delivered infrared free
electron laser (FEL) was investigated. The laser produced
macro pulses of 5 μs duration at a repetition rate of 30
Hz. Each macro pulse consisted of a train of 1 ps
micropulses repeating at 3 GHz. By tuning the laser
wavelength to the absorption peaks of the tissue or
molecular, the optimum wavelength for specific laser-tissue
interaction can be identified. Results of the investigation
showed that by using hollow waveguide delivery system, the
infrared FEL is suitable for the intraocular microsurgical
applications.},
Key = {fds245870}
}
@article{fds245875,
Author = {Hochberg, D and Edwards, G and Kephart, TW},
Title = {Representing structural information of helical charge
distributions in cylindrical coordinates},
Journal = {Physical Review E - Statistical Physics, Plasmas, Fluids,
and Related Interdisciplinary Topics},
Volume = {55},
Number = {3},
Pages = {3765-3768},
Publisher = {American Physical Society (APS)},
Year = {1997},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevE.55.3765},
Abstract = {Structural information in the local electric field produced
by helical charge distributions, such as dissolved DNA, is
revealed in a straightforward manner employing cylindrical
coordinates. Comparison of structure factors derived in
terms of cylindrical and helical coordinates is made. A
simple coordinate transformation serves to relate the Green
function in cylindrical and helical coordinates. We also
compare the electric field on the central axis of a single
helix as calculated in both systems. © 1997 The American
Physical Society.},
Doi = {10.1103/PhysRevE.55.3765},
Key = {fds245875}
}
@article{fds245876,
Author = {Tribble, J and Lamb, DC and Reinisch, L and Edwards,
G},
Title = {Dynamics of gelatin ablation due to free-electron-laser
irradiation},
Journal = {Physical Review E - Statistical Physics, Plasmas, Fluids,
and Related Interdisciplinary Topics},
Volume = {55},
Number = {6},
Pages = {7385-7389},
Publisher = {American Physical Society (APS)},
Year = {1997},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevE.55.7385},
Abstract = {We have carried out simultaneous, time-dependent
measurements of the free-electron-laser (FEL)-induced stress
transients and ablation plume in gelatin, which serves as a
model system for collagenous tissues. The Mark-III FEL is
tunable in the mid-IR (2–10 μm) and produces macropulses
of microsecond duration comprised of picosecond micropulses
separated by 350 ps. The macropulse duration was shortened
with a broadband, IR Pockels cell, producing pulse durations
as short as 60 ns and energies in the range of 0.1–1 mJ.
The IR beam was focused to a diameter of 112–210 μm,
depending on the wavelength, and measurements were made at
3.0, 3.36, and 6.45 μm. For fluences below the ablation
threshold, stress transients were measured and accounted for
with a standard thermoelastic mechanism. Of particular
interest were the measurements with fluences above the
ablation threshold, where two classes of dynamics were
observed. A cw HeNe beam monitors the plume: at 3.0 μm a
single maximum of the ’shadow’ is observed, while at
3.36 μm and 6.45 μm a second maximum also was resolved at
later times. In addition, at 3.36 μm and 6.45 μm the
duration of the momentum recoil is about twice as long as
that observed for comparable exposure parameters at 3.0 μm.
© 1997 The American Physical Society.},
Doi = {10.1103/PhysRevE.55.7385},
Key = {fds245876}
}
@article{fds304531,
Author = {Robinson, RD and Shen, JH and Joos, KM and Shetlar, DJ and Edwards, GS and O'Day, DM},
Title = {Healing of cultured human cornea after free electron laser
ablation},
Journal = {Investigative Ophthalmology and Visual Science},
Volume = {38},
Number = {4},
Pages = {S406},
Year = {1997},
ISSN = {0146-0404},
Abstract = {Purpose. To study the healing process in cultured human
corneas after Qswitched Er:YAG laser ablation. Methods.
Fresh human cadaver corneas within were ablated with a
Q-switched Er:YAG laser at 2.94 m wavelength. (100ns, 1 Hz)
The radiant exposure was 500 mJ/cm2. A focal crater was
created using between 60 and 80 pulses. A linear incision
was also formed by slowly scanning the laser over the
corneal surface. Each cornea was cultured on a tissue
supporting frame immediately after the ablation. Culture
media consisted of 92% minimum essential media, 8% fetal
bovine serum, 0.125% HEPES buffer solution, 0.125%
gentamicin, and 0.05% fungizone. The entire tissue frame and
media container were kept in an incubator at 37°C and 5%
C02. Serial macroscopic photographs of the cultured corneas
were taken during the healing process. Histology was
performed after 17 days of culture. Results. At 3 days, a
transient haze was observed within the craters which then
resolved between 7 and 14 days. No haze was seen along the
linear incision. Histologie sections of the cornea showed
complete re-epithelialization of the lased area. The
endothelium appeared unaffected. Conclusions. Cultured human
corneas may provide useful information regarding the healing
process following laser ablation.},
Key = {fds304531}
}
@article{fds304532,
Author = {Shen, JH and Joos, KJ and Shetlar, DJ and Robinson, RD and O'Day, DM and Edwards, GS},
Title = {Investigation of a clinical intraocular microsurgical device
using the infrared free electron laser},
Journal = {Investigative Ophthalmology and Visual Science},
Volume = {38},
Number = {4},
Pages = {S86},
Year = {1997},
ISSN = {0146-0404},
Abstract = {Purpose. The Free Electron Laser (PEL) has a wavelength
tunability range between 2 and 9 m in the mid-infrared
spectrum. It is capable of producing controlled predictable
laser-tissue interactions by selecting specific wavelengths.
However, delivery of this laser into the internal portion of
the eye is difficult because of strong water absorption in
this spectrum and the high peak power of the PEL. We
investigated the feasibility of a hollow waveguide
microsurgical device for FEL intraocular delivery Methods.
The infrared FEL beam was coupled into a metalliccoated
hollow waveguide (530 u,m inner diameter, l m length) and
transmitted to an autoclaved surgical probe. The probe tip
was an 18 gauge cannula fitted with a miniCaF2 window to
protect the waveguide. Retinal tissues in human and animal
cadaver eyes were incised at wavelengths of 2.94, 3.8, and
6.45 u.m. Results. Up to 6xl05 W peak power was delivered to
the intraocular tissues to successfully incise the retinas.
The system was able to deliver 60% of the FEL energy
.without damage to the waveguide or the surgical probe.
Conclusions. The hollow waveguide delivery system allows use
of the infrared FEL for intraocular microsurgical
use.},
Key = {fds304532}
}
@booklet{Edwards96,
Author = {Edwards, GS and Evertson, D and Gabella, W and Grant, R and King, TL and Kozub, J and Mendenhall, M and Shen, J and Shores, R and Storms, S and Traeger, RH},
Title = {Free-electron lasers: Reliability, performance, and beam
delivery},
Journal = {IEEE Journal on Selected Topics in Quantum
Electronics},
Volume = {2},
Number = {4},
Pages = {810-816},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {1996},
Month = {December},
ISSN = {1077-260X},
url = {http://dx.doi.org/10.1109/2944.577303},
Abstract = {The Vanderbilt free-electron laser (FEL) is a continuously
tunable source of pulsed, mid-infrared radiation. FEL
applications research has been underway for a decade. Recent
experimental advances in FEL ablation of soft tissue
indicate the potential for FEL-based protocols in surgery
and medicine. In anticipation of these medical applications,
the Vanderbilt FEL is being upgraded to meet the reliability
and performance standards for a medical laser. Facilities
for laser surgery have been constructed and equipped and
medical delivery systems are being developed for
pre-clinical and clinical research.},
Doi = {10.1109/2944.577303},
Key = {Edwards96}
}
@article{fds245869,
Author = {Joos, KM and Shen, JH and Edwards, GS and Shetlar, DJ and Khoury, JM and Robinson, RD},
Title = {Infrared free electron laser-tissue interactions with human
ocular tissues},
Journal = {Investigative Ophthalmology and Visual Science},
Volume = {37},
Number = {3},
Pages = {S431},
Year = {1996},
Month = {February},
ISSN = {0146-0404},
Abstract = {Purpose. To utilize the tuning capability of the Vanderbilt
University Free Electron Laser (FEL) to examine ocular
laser-tissue interactions with novel infrared wavelengths
for potential improvement of ophthalmic laser surgical
procedures. Methods. Human cadaver eyes were placed in 7.5%
dextran solution to normalize corneal thickness, and
solution was injected intraocularly to achieve a physiologic
intraocular pressure. Ocular tissues including cornea, iris,
retina and optic nerve were lased at the 2.94 μm water
absorbancy peak, 6.0 μm amide I band, 6.1 μm water
absorbancy peak, 6.45 μm amide II band, and 7.7 μm
delivered through a hollow waveguide. The Vanderbilt FEL
produces 5 μs long macropulses at 10 Hz with each
macropulse consisting of 1 ps micropulses at 3 GHz. Results.
Histologic examination of corneal tissue showed the least
amount of collateral damage (10 - 20 μm) with the 6.0 μm
amide I band, while marked shrinkage occurred with the 7.7
μm wavelength. For optic nerve tissue, the least amount of
collateral damage (0 μm visible) occurred at 6.1 μm water
absorbancy peak and 6.45 μm amide II band, while the most
damage (25 - 50 μm) was observed with the 7.7 μm
wavelength. Conclusions. A hollow waveguide is capable of
delivering useful infrared energy to ablate ocular tissues.
Different tissues may have different optimal wavelengths for
surgical laser procedures, and the tunable free election
laser has the unique capability to investigate those
potentially useful wavelengths.},
Key = {fds245869}
}
@booklet{Joos96,
Author = {Joos, KM and Shen, JH and Edwards, GS and Shetlar, DJ and Khoury, JM and Robinson, RD},
Title = {Infrared free electron laser-tissue interactions with
human},
Journal = {Investigative Ophthalmology \& Visual Science},
Volume = {37},
Number = {3},
Pages = {1985-1985},
Year = {1996},
Month = {February},
Key = {Joos96}
}
@article{fds245867,
Author = {Joos, KMMD and Edwards, GS and Shen, JH and Shetlar, D and Robinson, R and O'Day, DMD},
Title = {Free Electron Laser (FEL) laser-tissue interaction with
human cornea and optic nerve},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2673},
Pages = {89-92},
Year = {1996},
Month = {January},
Abstract = {A free electron laser (FEL) may be tuned to novel
wavelengths to explore laser-tissue interactions for
development or improvement of laser surgical procedures.
This study investigated the effect of selected infrared
wavelengths upon human cornea and optic nerve tissues. Human
cadaver eyes were placed in 10% dextran solution to
normalize corneal thickness, and solution was injected
intraocularly to achieve a physiologic intraocular pressure.
The corneas and optic nerves were lased with the 6.0
micrometer amide I band, 6.1 micrometer water absorbency
peak, 6.45 micrometer amide II band, and 7.7 micrometer. The
Vanderbilt FEL produces 5 microsecond long macropulses at 10
Hz with each macropulse consisting of 1 ps micropulses at 3
GHz. Histologic examination of the corneal tissue showed the
least amount of collateral damage (10 - 20 micrometers) with
the 6.0 micrometer amide I band, while marked shrinkage
occurred with the 7.7 micrometer wavelength. For optic nerve
tissue, the least amount of collateral damage (0 micrometer
visible) occurred at 6.1 micrometer water absorbency peak
and 6.45 micrometer amide II band, while the most damage (30
- 50 micrometers) was observed with the 7.7 micrometer
wavelength. We conclude that different tissues may have
different optimal wavelengths for surgical laser
procedures.},
Key = {fds245867}
}
@article{fds245868,
Author = {Harris, DM and Reinisch, L and Edwards, GS and Yessik, MJ and Ashrafi,
S and Santos-Sacchi, J},
Title = {Midinfrared ablation of dentin with the Vanderbilt
FEL},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2672},
Pages = {165-175},
Year = {1996},
Month = {January},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.238765},
Abstract = {Absorption spectra of 0.1 - 0.2 mm thick, dehydrated
sections of human teeth were measured in the transmission
mode with a Bruker FT-IR spectrometer from 2.5 - 20 μm.
Absorption peaks for amide I, II and III, carbonate and
phosphate were identified. Craters were ablated in dentin
and enamel using a tunable FEL at 6.45 μm at various
fluences. Pulse duration: 3 μs; spot size (Gaussian, FWHM):
300 μm; repetition rate: 10 Hz. Crater depth and width were
measured from digitized optical images. Ablation rates were
computed from crater depth and volume data. Selected
specimens were examined with scanning electron microscopy to
determine ablation surface characteristics. Depth of thermal
damage and dentinal tubule morphology were estimated from
SEM examination of fractures through ablation sites.
Functions describing crater depth vs. number of pulses
(quadratic function) were not the same as crater volume vs.
number of pulses (linear function). Crater depth decreases
with successive pulses, concurrently, the crater width
increases. Thus, each pulse removes approximately a constant
volume. Material was observed to flow through the dentinal
tubules during and after ablation. Patent tubules on crater
walls and floor were observed with SEM. Ablation rates in
dentin were approximately 3× those in enamel at 6.45 μm.
Ablation rates and surface characteristics varied across
wavelengths from 5.8 to 8.0 μm.},
Doi = {10.1117/12.238765},
Key = {fds245868}
}
@article{fds245864,
Author = {Johnson, JB and Becker, K and Edwards, G},
Title = {Pressure corrections for CoCl2 as a thermometer in an
analytic ultracentrifuge.},
Journal = {Analytical biochemistry},
Volume = {227},
Number = {2},
Pages = {385-387},
Year = {1995},
Month = {May},
ISSN = {0003-2697},
url = {http://dx.doi.org/10.1006/abio.1995.1295},
Doi = {10.1006/abio.1995.1295},
Key = {fds245864}
}
@booklet{Zhang95,
Author = {Zhang, MZ and Edwards, GS and Reinisch, L and Vasagrande, VA and Mckanna, JA},
Title = {Microglial responses to free-electron laser incisions in
rat-brain},
Journal = {Faseb Journal},
Volume = {9},
Number = {3},
Pages = {A382-A382},
Year = {1995},
Month = {March},
Key = {Zhang95}
}
@article{fds245865,
Author = {Edwards, GS},
Title = {Biomedical and potential clinical applications for pulsed
lasers operating near 6.45 um},
Journal = {Optical Engineering},
Volume = {34},
Number = {5},
Pages = {1524-1525},
Publisher = {SPIE-Intl Soc Optical Eng},
Year = {1995},
Month = {January},
url = {http://dx.doi.org/10.1117/12.201620},
Abstract = {The operating parameters of the Vanderbilt free electron
laser (FEL) are summarized. Effort are underway to develop
compact FELs for medical applications. While further
investigations of both the ablation mechanism, in particular
the role of the pulse structure, and the biological response
will continue at Vanderbilt and other FEL centers, a glaring
need exists for an alternative, preferably tabletop source.
A great deal of biomedical research need to be done to
investigate the biological response to laser ablation via
the vibrational modes of proteins.},
Doi = {10.1117/12.201620},
Key = {fds245865}
}
@article{fds245862,
Author = {Johnson, JB and Edwards, G and Mendenhall, M},
Title = {Low-cost, high-performance array detector for spectroscopy
based on a charge-coupled photodiode},
Journal = {Review of Scientific Instruments},
Volume = {65},
Number = {5},
Pages = {1782-1783},
Publisher = {AIP Publishing},
Year = {1994},
Month = {December},
url = {http://dx.doi.org/10.1063/1.1144826},
Abstract = {We describe a nitrogen-cooled array detector system based on
the Thomson TH 7832A charge-coupled photodiode. Performance
comparisons are made between this system and others based on
two-dimensional CCDs. The TH 7832A compares favorably in
resolution, spectral range, and readout speed. Analysis of
read and shot noise contributions identifies classes of
experiments for which the larger read noise of the TH 7832A
is inconsequential.},
Doi = {10.1063/1.1144826},
Key = {fds245862}
}
@article{fds245863,
Author = {Becker, K and Johnson, JB and Edwards, G},
Title = {Broadband Pockels cell and driver for a Mark III-type free
electron laser},
Journal = {Review of Scientific Instruments},
Volume = {65},
Number = {5},
Pages = {1496-1501},
Publisher = {AIP Publishing},
Year = {1994},
Month = {December},
url = {http://dx.doi.org/10.1063/1.1144881},
Abstract = {A Pockels cell with an operating range of 2 to 10 μm has
been designed, constructed, and tested for use with the
Vanderbilt free electron laser. The Pockels cell can be
continuously adjusted to switch out from 80 ns to the full 6
μs duration of the FEL macropulse. The extinction ratio is
better than 180:1 and the optical pulse is square with rise
and fall times under 10 ns. The high voltage drivers are
based on semiconductor switches that are compact and mounted
directly to the Pockels cell; this design avoids problems
associated with fast, high voltage pulses traveling in
cables. In addition, designs for two alternative drivers to
generate optical pulses with durations ranging from a few
nanoseconds down to the subnanosecond regime are presented
here. Prototypes using single high voltage transitions have
been constructed and tested electrically.},
Doi = {10.1063/1.1144881},
Key = {fds245863}
}
@article{fds245866,
Author = {Edwards, G and Logan, R and Copeland, M and Reinisch, L and Davidson, J and Johnson, B and Maciunas, R and Mendenhall, M and Ossoff, R and Tribble,
J},
Title = {Tissue ablation by a free-electron laser tuned to the amide
II band.},
Journal = {Nature},
Volume = {371},
Number = {6496},
Pages = {416-419},
Year = {1994},
Month = {September},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/371416a0},
Abstract = {Efforts to ablate soft tissue with conventional lasers have
been limited by collateral damage and by concern over
potential photochemical effects. Motivated by the
thermal-confinement model, past infrared investigations
targeted the OH-stretch mode of water with fast pulses from
lasers emitting near 3,000 nm (refs 1, 7-9). What does a
free-electron laser offer for the investigation of tissue
ablation? Operating at non-photochemical single-photon
energies, these infrared sources can produce trains of
picosecond pulses tunable to the vibrational modes of
proteins, lipids and/or water. We report here that targeting
free-electron laser radiation to the amide II band of
proteins leads to tissue ablation characterized by minimal
collateral damage while maintaining a substantial ablation
rate. To account for these observations we propose a novel
ablation mechanism based on compromising tissue through
resonant denaturation of structural proteins.},
Doi = {10.1038/371416a0},
Key = {fds245866}
}
@article{fds347640,
Author = {Edwards, G and Tribble, J and Bruce Johnson and J},
Title = {Partitioning-of-energy model for laser ablation of
tissue},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2134},
Pages = {134-143},
Year = {1994},
Month = {August},
url = {http://dx.doi.org/10.1117/12.182929},
Abstract = {A theoretical model is presented to account for the
experimental observation that infrared tissue ablation is
optimized by the use of wavelengths near the amide II band
of proteins. The model recognizes the partitioned absorption
of IR photons between protein and water due to overlapping
spectral features along with the dynamics of biopolymers,
the loss of mechanical integrity in proteins, and the
explosive role played by the vaporization of water. The
theoretical foundation for this model can be found in
previous accounts of thermal confinement, multicoinponent
models , and selective photothermolysis.},
Doi = {10.1117/12.182929},
Key = {fds347640}
}
@article{fds347338,
Author = {Mu, R and Henderson, DO and Johnson, JB and Edwards,
GS},
Title = {Pulsed JR-FEL applications for the characterization of
infrared optical materials},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2138},
Pages = {97-106},
Year = {1994},
Month = {July},
url = {http://dx.doi.org/10.1117/12.181347},
Abstract = {Theoretical consideration of thermal lens effect due to
linear and nonlinear opiical absorption is presented. Based
on this model, Zscan technique, especially two-color Z-scan
can be used to detect very low level of unpurities or
defects in optical materials. Depending upon the optical crs
section of the particular species being probed, two-color
Z-scan can detect impurities, for example, the OH groups in
fused silica at sub-ppm level by weight or
better.},
Doi = {10.1117/12.181347},
Key = {fds347338}
}
@article{fds347339,
Author = {Edwards, G and Logan, R and Copeland, M and Reinisch, L and Davidson, J and Johnson, B and MacIunas, R and Mendenhall, M and Ossoff, R and Tribble,
J and Werkhaven, J and O'Day, D},
Title = {Two years of free-electron laser applications research in
biological physics},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {2138},
Pages = {35-40},
Year = {1994},
Month = {July},
url = {http://dx.doi.org/10.1117/12.181340},
Abstract = {The Vanderbilt free-electron laser has been operational for
several years. This extended collaboration has been
investigating outstanding problems in biological physics and
medical physics with several research goals in mind. Our
most fundamental goal is to improve the understanding of
intermolecular and intramolecular vibrational energy
transfer mechanisms in biopolymers. Our approach is to
pursue both experimental and theoretical research addressing
vibrational energy transfer in biological physics. The
remaining goals can be summarized as the application of our
fundamental advancements in polymer physics to molecular
biology and to clinical and surgical medicine. One of our
most successful research programs to date has been a
systematic investigation of the wavelength dependence for
infrared laser ablation of tissue, highlighting the
potential for clinical and surgical applications of infrared
light delivered with picosecond pulses. This research
program demonstrates the role of molecular mechanisms for
vibrational energy transfer in determining the ablative
properties of tissue.},
Doi = {10.1117/12.181340},
Key = {fds347339}
}
@article{fds245859,
Author = {Edwards, G and Hochberg, D and Kephart, TW},
Title = {Structure in the electric potential emanating from
DNA},
Journal = {Physical Review E},
Volume = {50},
Number = {2},
Pages = {R698-R701},
Publisher = {American Physical Society (APS)},
Year = {1994},
Month = {January},
ISSN = {1063-651X},
url = {http://dx.doi.org/10.1103/PhysRevE.50.R698},
Abstract = {We present an analytical model, based on a Green-function
technique, for the electric potential surrounding dissolved
DNA which treats the full, discrete charge distribution of
homopolymer B-DNA and the aqueous solvent as concentric,
dielectric cylinders. The resulting expressions manifest the
symmetry of the system, with terms equivalent to a
continuous line charge and with distinctive helical terms
both due to the sugar-phosphate backbone and due to the base
pairs. This theoretical approach quantifies the structural
information in the potential with continuing approach to the
DNA surface. © 1994 The American Physical
Society.},
Doi = {10.1103/PhysRevE.50.R698},
Key = {fds245859}
}
@article{fds245860,
Author = {Hochberg, D and Kephart, TW and Edwards, G},
Title = {Structural information in the local electric field of
dissolved B-DNA},
Journal = {Physical Review E},
Volume = {49},
Number = {1},
Pages = {851-867},
Publisher = {American Physical Society (APS)},
Year = {1994},
Month = {January},
ISSN = {1063-651X},
url = {http://dx.doi.org/10.1103/PhysRevE.49.851},
Abstract = {We have developed a theoretical model of the electric
potential and field for B-DNA in solution to investigate the
persistence of structural information in the local field. A
Green-function technique is used to account for the
phosphate groups, the dominant charges of the
polyelectrolyte DNA, as discrete surface charges exhibiting
helical geometry. In addition to the DNA macromolecule, a
region of condensed ions and bulk solvent are treated as
dielectric media with cylindrical symmetry. We have derived
analytical expressions that manifest the symmetry of the
system. The leading term is equivalent to that of a
continuous line charge and thus only reflects cylindrical
symmetry. Information reflecting the helical structure is
contained in the terms of higher order. The effective decay
length for helical information in the local electric field
is approximately 5 beyond the surface of DNA. These results
have significance for investigations of nucleic-acid-protein
interactions and for experimental efforts to image DNA with
scanning force microscopies. © 1994 The American Physical
Society.},
Doi = {10.1103/PhysRevE.49.851},
Key = {fds245860}
}
@article{fds245861,
Author = {Henderson, DO and Mu, R and Silberman, E and Johnson, JB and Edwards,
GS},
Title = {FEL investigations of energy transfer in condensed phase
systems},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {1854},
Pages = {105-116},
Year = {1993},
Month = {December},
Abstract = {The vibrational dynamics of O-H groups in fused silica have
been examined by a time-resolved pump-probe technique using
the Vanderbilt Free Electron Laser (FEL). We consider two
effects, local heating and transient thermal lensing, which
can influence measured T1 values in one color pump-probe
measurements. The dependence of these two effects on both
the micropulse spacing and the total number of micropulses
delivered to the sample are analyzed in detail for the
O-H/SiO2 system. The results indicate that transient thermal
lensing can significantly influence the measured probe
signal. The local heating may cause thermally induced
changes in the ground state population of the absorber,
thereby complicating the analysis of the relaxation
dynamics.},
Key = {fds245861}
}
@booklet{Edwards93,
Author = {Edwards, GS and Johnson, B and Kozub, J and Tribble, J and Wagner,
K},
Title = {Biomedical applications of free-electron
lasers},
Journal = {Optical Engineering},
Volume = {32},
Number = {2},
Pages = {314-319},
Year = {1993},
Month = {February},
Key = {Edwards93}
}
@article{fds331602,
Author = {Edwards, G and Johnson, B and Kozub, J and Tribble, J and Wagner,
K},
Title = {Applications of free-electron lasers to measurements of
energy transfer in biopolymers and materials},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {1646},
Pages = {13-23},
Publisher = {SPIE},
Year = {1992},
Month = {August},
ISBN = {9780819407924},
url = {http://dx.doi.org/10.1117/12.137462},
Abstract = {Free-electron lasers (FELs) provide tunable, pulsed
radiation in the infrared. Using the FEL as a pump beam, we
are investigating the mechanisms for energy transfer between
localized vibrational modes and between vibrational modes
and lattice or phonon modes. Either a laser-Raman system or
a Fourier transform infrared (FTIR) spectrometer will serve
as the probe beam, with the attribute of placing the burden
of detection on two conventional spectroscopic techniques
that circumvent the limited response of infrared detectors.
More specifically, the Raman effect inelastically shifts an
exciting laser line, typically a visible frequency, by the
energy of the vibrational mode; however, the shifted Raman
lines also lie in the visible, allowing for detection with
highly efficient visible detectors. With regards to FTIR
spectroscopy, the multiplex advantage yields a distinct
benefit for infrared detector response. Our group is
investigating intramolecular and intermolecular energy
transfer processes in both biopolymers and more traditional
materials. For example, alkali halides contain a number of
defect types that effectively transfer energy in an
intermolecular process. Similarly, the functioning of
biopolymers depends on efficient intramolecular energy
transfer. Understanding these mechanisms will enhance our
ability to modify biopolymers and materials with
applications to biology, medicine, and materials
science.},
Doi = {10.1117/12.137462},
Key = {fds331602}
}
@article{fds245857,
Author = {Tribble, J and Kozub, J and Aly, A and Ossoff, R and Edwards,
G},
Title = {Role of immersion refractometry for investigating
laser-induced effects in cells.},
Journal = {Lasers in surgery and medicine},
Volume = {12},
Number = {4},
Pages = {459-463},
Year = {1992},
Month = {January},
ISSN = {0196-8092},
url = {http://dx.doi.org/10.1002/lsm.1900120416},
Abstract = {The broad background of scattered light observed in spectra
of cell suspensions is reduced by factors of up to 20 by
immersion refractometry allowing for improved spectroscopic
determination of the absorption properties of cells in the
325-820 nm range. Refractive-index matched spectra of E.
coli C1a exhibit a set of resonant features near 422, 561,
and 582 nm. Exposure wavelengths are chosen based on this
spectrum and cell viability is investigated in E. coli
suspensions exposed to 350, 400, 422, 440, and 700 nm
radiation delivered in nanosecond pulses with total doses
from 500 millijoules to 60 Joules. We observe a loss in cell
viability for doses greater than 1 Joule at 422 nm and for
all doses at other wavelengths; exposures of less than 1
Joule at 422 nm enhance growth. Excluding exposures at
wavelengths within the resonant feature, longer wavelengths
are less effective at reducing the viability of E. coli C1a.
This indicates the occurrence of at least two absorption
processes.},
Doi = {10.1002/lsm.1900120416},
Key = {fds245857}
}
@article{fds245858,
Author = {Edwards, G and Ying, G and Tribble, J},
Title = {Role of counterions in the gigahertz relaxation of wet
DNA},
Journal = {Physical Review A},
Volume = {45},
Number = {12},
Pages = {R8344-R8347},
Publisher = {American Physical Society (APS)},
Year = {1992},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.45.R8344},
Abstract = {We have measured the dielectric properties of concentrated
solutions and gels (30 mg/ml) of random-sequenced DNA from
E. coli in the 400-MHz26-GHz range. Two Debye-type
relaxations are evident, one with a relaxation time near 9
ps and attributable to the classical Debye relaxation of
water. More noteworthy is a second relaxation process with a
characteristic time in the 20200-ps range, i.e., a
relaxation frequency in the 0.88-GHz range, depending upon
the species of the counterions and the temperature. The
slower relaxation process has an enthalpy of 3.3 kcal/mol
and is accounted for by a counterion-based relaxation
process. These experimental results are considered in terms
of two models from polyelectrolyte theory, one by Oosawa
[Biopolymers 9, 677 (1970)] and Wyllie [in Dielectric and
Related Molecular Processes, edited by M. Davies (American
Chemical Society, Washington, D.C., 1972), Vol. 1], and the
other by Manning [Q. Rev. Biophys. 11, 179 (1978); Acc.
Chem. Res. 12, 443 (1979)], and we propose that different
ion-based relaxation mechanisms dominate in different
hydration regimes. © 1992 The American Physical
Society.},
Doi = {10.1103/PhysRevA.45.R8344},
Key = {fds245858}
}
@article{fds245856,
Author = {Tolk, NH and Brau, CA and Edwards, GS and Margaritondo, G and McKinley,
JT},
Title = {The vanderbilt free-electron laser center for biomedical and
materials research},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {1552},
Pages = {7-13},
Year = {1991},
Month = {December},
url = {http://dx.doi.org/10.1117/12.50587},
Abstract = {The newly commissioned Vanderbilt Free Electron Laser Center
for Biomedical and Materials Research is a multidisciplinary
users facility intended as an international resource. It
provides extremely intense, continuously tunable, pulsed
radiation in the mid-infrared (2-10 j.tm). Projects already
underway include the linear and nonlinear interaction of
laser radiation with optical materials, semiconductors, and
mammalian tissue, the spectroscopy of species adsorbed on
surfaces, measurement of vibrational energy transfer in DNA
and RNA, the dynamics of proteins in cell membranes, the
biomodulation of wound healing by lasers, image-guided
stereotactic neurosurgery, and the use of monochromatic
X-rays in medical imaging and therapy. The purpose of this
article is to introduce the machine to the user community
and to describe some of the new experimental opportunities
that it makes possible. Details of several research projects
are presented.},
Doi = {10.1117/12.50587},
Key = {fds245856}
}
@article{fds245855,
Author = {Edwards, G and Liu, C},
Title = {Sequence dependence of low-frequency Raman-active modes in
nucleic acids},
Journal = {Physical Review A},
Volume = {44},
Number = {4},
Pages = {2709-2717},
Publisher = {American Physical Society (APS)},
Year = {1991},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.44.2709},
Abstract = {We have measured the low-frequency (<200 cm-1) Raman
activity of dehydrated fibers and films of polynucleotides
and random-sequenced nucleic acids. The spectra exhibit a
pronounced, unresolved band in the range 10150 cm-1. A
nonlinear least-squares algorithm optimally fits the spectra
from all samples with three low-frequency modes in the range
25100 cm-1 and a fourth mode near 200 cm-1. A mode near 25
cm-1 is sequence independent, but does shift to marginally
higher frequency in RNA. The mode frequencies and oscillator
strengths of two modes in the range 35100 cm-1 exhibit
sequence dependence. © 1991 The American Physical
Society.},
Doi = {10.1103/PhysRevA.44.2709},
Key = {fds245855}
}
@article{fds245853,
Author = {Young, L and Prabhu, VV and Prohofsky, EW and Edwards,
GS},
Title = {Prediction of modes with dominant base roll and propeller
twist in B-DNA poly(dA)-poly(dT)},
Journal = {Physical Review A},
Volume = {41},
Number = {12},
Pages = {7020-7023},
Publisher = {American Physical Society (APS)},
Year = {1990},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.41.7020},
Abstract = {In solving the secular equation of a one-dimensional
infinite lattice model of poly(dA)-poly(dT), we obtain
dispersion relations. [The notation poly(dA)-poly(dT) means
that one strand contains only adenine (A) bases, and the
other only thymine (T) bases.] We solve the equation for
consecutive refinements of the nonbonded force constants
based on Raman, Brillouin, and neutron scattering and
Fourier-transform infrared experiments in both
polynucleotides and random sequence DNA. When these
eigenvectors are examined for base roll and propeller twist,
such characteristics are found to be dominant in modes
around 50 cm-1. © 1990 The American Physical
Society.},
Doi = {10.1103/PhysRevA.41.7020},
Key = {fds245853}
}
@article{fds245854,
Author = {Liu, C and Edwards, GS and Morgan, S and Silberman,
E},
Title = {Low-frequency, Raman-active vibrational modes of
poly(dA)poly(dT)},
Journal = {Physical Review A},
Volume = {40},
Number = {12},
Pages = {7394-7397},
Publisher = {American Physical Society (APS)},
Year = {1989},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.40.7394},
Abstract = {The Raman activity of low-frequency (20-300 cm-1)
vibrational modes of dehydrated, oriented fibers of the
sodium salts of poly(dA)poly(dT) and random sequenced DNA
have been measured. Distinct bands near 60, 75-100, and
125-140 cm-1 are resolved in poly(dA)poly(dT). The Raman
activity of the two lowest bands correlate with the
previously observed infrared activity of poly(dA)poly(dT).
The apparent reduction in spectral line broadening for
poly(dA)poly(dT), as demonstrated by this and previous
measurements of a number of different polynucleotides, is
considered as possible evidence for inhomogeneous line
broadening. © 1989 The American Physical
Society.},
Doi = {10.1103/PhysRevA.40.7394},
Key = {fds245854}
}
@booklet{Edwards88,
Author = {Edwards, GS and Tolk, NH},
Title = {Vanderbilt University FEL center for biomedical and
materials research},
Journal = {Nuclear Inst. and Methods in Physics Research,
A},
Volume = {272},
Number = {1-2},
Pages = {37-39},
Publisher = {Elsevier BV},
Year = {1988},
Month = {January},
ISSN = {0168-9002},
url = {http://dx.doi.org/10.1016/0168-9002(88)90191-X},
Doi = {10.1016/0168-9002(88)90191-X},
Key = {Edwards88}
}
@booklet{Powell87,
Author = {Powell, JW and Edwards, GS and Genzel, L and Kremer, F and Wittlin, A and Kubasek, W and Peticolas, W},
Title = {Investigation of far-infrared vibrational modes in
polynucleotides},
Journal = {Physical Review A},
Volume = {35},
Number = {9},
Pages = {3929-3939},
Publisher = {American Physical Society (APS)},
Year = {1987},
Month = {January},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.35.3929},
Abstract = {Far-infrared measurements (40500 cm-1) of vacuum-dried,
free-standing, unoriented films of the polynucleotides
poly(dA)poly(dT), poly(dA-dT)poly(dA-dT) , and
poly(dG)poly(dC) and the ribonucleotide poly(rA)poly(rU)
under various salting conditions are reported. Spectral
features that depend on temperature, crystallinity, and
salting conditions have been observed. Of most interest are
four sharp bands near 63, 83, 100, and 110 cm-1 in
polycrystalline poly(dA)poly(dT). These low-frequency (<240
cm-1) observations are discussed in terms of a
lattice-dynamical model of homopolymer DNA. © 1987 The
American Physical Society.},
Doi = {10.1103/PhysRevA.35.3929},
Key = {Powell87}
}
@article{fds245852,
Author = {Edwards, GS and Genzel, L and Peticolas, WL and Rupprecht,
A},
Title = {Measurements of a large anisotropy in the swelling of
oriented DNA films in aqueous solution.},
Journal = {Biopolymers},
Volume = {25},
Number = {2},
Pages = {223-227},
Year = {1986},
Month = {February},
url = {http://dx.doi.org/10.1002/bip.360250203},
Doi = {10.1002/bip.360250203},
Key = {fds245852}
}
@booklet{Davis86,
Author = {Davis, CC and Edwards, GS and Swicord, ML and Sagripanti, J and Saffer,
J},
Title = {Direct excitation of internal modes of DNA by
microwaves},
Journal = {Bioelectrochemistry and Bioenergetics},
Volume = {16},
Number = {1},
Pages = {63-76},
Publisher = {Elsevier BV},
Year = {1986},
Month = {January},
ISSN = {0302-4598},
url = {http://dx.doi.org/10.1016/0302-4598(86)80046-0},
Abstract = {We have been studying the microwave absorption
characteristics of various forms of DNA. Our observations
have demonstrated that long-chain DNA in saline buffer does
not absorb microwaves significantly more than its solvent,
but that specific short-length molecules can absorb
microwaves resonantly. The most satisfactory explanation of
these microwave absorption phenomena invokes the excitation
of internal acoustic modes of the molecule. There is good
agreement between our experimental observations and a
lattice-dynamical/normal-mode analysis of the vibrational
motion of the double helical DNA.},
Doi = {10.1016/0302-4598(86)80046-0},
Key = {Davis86}
}
@article{fds245851,
Author = {Swicord, ML and Davis, CC and Edwards, GS and Saffer,
JD},
Title = {MICROWAVE-FIELD DRIVEN ACOUSTIC MODES OF
DNA.},
Journal = {Bioengineering, Proceedings of the Northeast
Conference},
Pages = {226-229},
Year = {1985},
Month = {December},
Abstract = {The microwave absorption characteristics of various forms of
DNA in the frequency range between 0. 1 and 12 GHz are
analyzed. The results are summarized as follows: the
microwave absorption of aqueous solutions of long-chain DNA
(tens of thousands of base-pairs in length) is not
significantly different from the background absorption of
the solvent; long-chain DNA that has been extensively
sheared can exhibit substantially higher absorption per mass
than the solvent; long-chain DNA that is nicked and
subsequently broken into shorter fragments by the action of
the endonuclease DNAse 1 will show a microwave absorption
that rises with time during the action of the endonuclease.
This strongly suggests a length dependence of the microwave
absorption, and monodisperse aqueous solutions containing
DNA molecules of well-defined length exhibit distinct
absorption resonances. These resonances are surprisingly
narrow.},
Key = {fds245851}
}
@booklet{Edwards85,
Author = {Edwards, GS and Davis, CC and Saffer, JD and Swicord,
ML},
Title = {Microwave-field-driven acoustic modes in
DNA.},
Journal = {Biophysical journal},
Volume = {47},
Number = {6},
Pages = {799-807},
Year = {1985},
Month = {June},
url = {http://dx.doi.org/10.1016/s0006-3495(85)83984-9},
Abstract = {The direct coupling of a microwave field to selected DNA
molecules is demonstrated using standard dielectrometry. The
absorption is resonant with a typical lifetime of 300 ps.
Such a long lifetime is unexpected for DNA in aqueous
solution at room temperature. Resonant absorption at
fundamental and harmonic frequencies for both supercoiled
circular and linear DNA agrees with an acoustic mode model.
Our associated acoustic velocities for linear DNA are very
close to the acoustic velocity of the longitudinal acoustic
mode independently observed on DNA fibers using Brillouin
spectroscopy. The difference in acoustic velocities for
supercoiled circular and linear DNA is discussed in terms of
solvent shielding of the nonbonded potentials in
DNA.},
Doi = {10.1016/s0006-3495(85)83984-9},
Key = {Edwards85}
}
@article{fds304530,
Author = {Edwards, GS and Davis, CC and Saffer, JD and Swicord,
ML},
Title = {Erratum: Resonant microwave absorption of selected DNA
molecules (Physical Review Letters (1984) 53, 21
(2060))},
Journal = {Physical Review Letters},
Volume = {53},
Number = {21},
Pages = {2060},
Publisher = {American Physical Society (APS)},
Year = {1984},
Month = {December},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/PhysRevLett.53.2060.5},
Doi = {10.1103/PhysRevLett.53.2060.5},
Key = {fds304530}
}
@booklet{Edwards84a,
Author = {Edwards, GS and Davis, CC and Saffer, JD and Swicord,
ML},
Title = {Resonant microwave absorption of selected DNA
molecules},
Journal = {Physical Review Letters},
Volume = {53},
Number = {13},
Pages = {1284-1287},
Publisher = {American Physical Society (APS)},
Year = {1984},
Month = {January},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/PhysRevLett.53.1284},
Abstract = {The resonant absorption of microwave energy by aqueous
solutions containing DNA of known length is experimentally
demonstrated. The resonances observed have relaxation times
of hundreds of picoseconds. Absorption by linear and
supercoiled circular DNA molecules is discussed in terms of
a mechanism involving microwave excitation of acoustic modes
of the double helix. © 1984 The American Physical
Society.},
Doi = {10.1103/PhysRevLett.53.1284},
Key = {Edwards84a}
}
@booklet{Edwards84,
Author = {Edwards, GS},
Title = {Correction},
Journal = {Physical Review Letters},
Volume = {53},
Number = {21},
Pages = {2060-2060},
Year = {1984},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/PhysRevLett.53.2060.5},
Doi = {10.1103/PhysRevLett.53.2060.5},
Key = {Edwards84}
}
@article{fds245850,
Author = {Swicord, ML and Edwards, GS and Sagripanti, JL and Davis,
CC},
Title = {Chain-length-dependent microwave absorption of
DNA.},
Journal = {Biopolymers},
Volume = {22},
Number = {12},
Pages = {2513-2516},
Year = {1983},
Month = {December},
url = {http://dx.doi.org/10.1002/bip.360221205},
Doi = {10.1002/bip.360221205},
Key = {fds245850}
}
%% Papers Submitted
@article{fds347939,
Author = {and G.S. Edwards},
Title = {Shape changes of cytoskeletal actin filaments},
Journal = {Biophysical Journal},
Year = {2019},
Abstract = {Cytoskeletal actin filaments are constrained by dynamic
crosslinks, actively driven by myosin mini-filaments,
stressed by their surrounding cytoskeleton, and their shape
changes occur in a viscoelastic cytosol. The beam equation
has been applied to cytoskeletal actin filaments to predict
their shape changes. The shape change simply scales with the
magnitude of the force applied by actomyosin cross-bridges.
In contrast, there are qualitatively distinct classes of
shape changes depending on the length of the actin filaments
and the magnitude of cytoskeletal stress. These modelling
results were then connected to previous experimental
observations. Consequently, order-of-magnitude estimates
were carried out both for Stokes’ drag coefficient, the
viscosity, and the Reynolds Number for the cytosol and also
for tissue-scale forces and stresses during morphogenesis.
Knowledge of the diversity of shape changes for cytoskeletal
actin filaments advances the mechanistic understanding of
how molecular piconewton forces scale into nanonewton
cellular and tissue forces.},
Key = {fds347939}
}