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Full-Text Articles in Physics
A Careful Reassessment Of Globular Cluster Multiple Population Radial Distributions With Sloan Digital Sky Survey And Johnson-Cousins Broadband Photometry, Willem B. Hoogendam, Jason P. Smolinski
A Careful Reassessment Of Globular Cluster Multiple Population Radial Distributions With Sloan Digital Sky Survey And Johnson-Cousins Broadband Photometry, Willem B. Hoogendam, Jason P. Smolinski
University Faculty Publications and Creative Works
Inconsistencies regarding the nature of globular cluster (GC) multiple population radial distributions is a matter for concern given their role in testing or validating cluster dynamical evolution modeling. In this study, we present a reanalysis of eight GC radial distributions using publicly available ground-based ugriz and UBVRI photometry; correcting for a systematic error identified in the literature. We detail the need for including and considering not only Kolmogorov-Smirnov (K-S) probabilities but critical K-S statistic values as well when drawing conclusions from radial distributions, as well as the impact of sample incompleteness. Revised cumulative radial distributions are presented, and the literature …
Re-Examining The Radial Distributions Of M13 Multiple Populations, Jason P. Smolinski, Willem B. Hoogendam, Alex J. Van Kooten, Peyton Benac
Re-Examining The Radial Distributions Of M13 Multiple Populations, Jason P. Smolinski, Willem B. Hoogendam, Alex J. Van Kooten, Peyton Benac
University Faculty Publications and Creative Works
We seek to resolve the tension in the literature regarding the presence of radially segregated multiple populations in the Galactic globular cluster M13. Previous studies of this nearby cluster have presented discordant results about the degree of dynamical mixing in M13's inner region. Using ground-based (UBVI) photometry, we show that cumulative radial distributions of stars on the blue and red sides of the red giant branch are statistically identical. Interestingly, these results are obtained using data from large-aperture, ground-based telescopes as well as a more modestly sized instrument, and both are in agreement with previous work done using Hubble Space …
Involvement Of The Extrinsic And Intrinsic Pathways In Ultraviolet B-Induced Apoptosis Of Corneal Epithelial Cells, John L. Ubels, Courtney D. Glupker, Mark P. Schotanus, Loren D. Haarsma
Involvement Of The Extrinsic And Intrinsic Pathways In Ultraviolet B-Induced Apoptosis Of Corneal Epithelial Cells, John L. Ubels, Courtney D. Glupker, Mark P. Schotanus, Loren D. Haarsma
University Faculty Publications and Creative Works
The goal of this study was to elucidate the pathway by which UVB initiates efflux of K+ and subsequently apoptosis in human corneal limbal epithelial (HCLE) cells. The initial focus of the study was on the extrinsic pathway involving Fas. HCLE cells transfected with Fas siRNA were exposed to 80-150 mJ/cm2 UVB and incubated in culture medium with 5.5 mM K+. Knockdown of Fas resulted in limited reduction in UVB-induced caspase-8 and -3 activity. Patch-clamp recordings showed no difference in UVB-induced normalized K+ currents between Fas transfected and control cells. Knockdown of caspase-8 had no effect on the activation of …
Enhancement Of Vitamin D Metabolites In The Eye Following Vitamin D3 Supplementation And Uv-B Irradiation, Yanping Lin, John L. Ubels, Mark P. Schotanus, Zhaohong Yin
Enhancement Of Vitamin D Metabolites In The Eye Following Vitamin D3 Supplementation And Uv-B Irradiation, Yanping Lin, John L. Ubels, Mark P. Schotanus, Zhaohong Yin
University Faculty Publications and Creative Works
This study was designed to measure vitamin D metabolites in the aqueous and vitreous humor and in tear fluid, and to determine if dietary vitamin D3 supplementation affects these levels. We also determined if the corneal epithelium can synthesize vitamin D following UV-B exposure. Methods: Rabbits were fed a control or vitamin D3 supplemented diet. Pilocarpine- stimulated tear fluid was collected and aqueous and vitreous humor were drawn from enucleated eyes. Plasma vitamin D was also measured. To test for epithelial vitamin D synthesis, a human corneal limbal epithelial cell line was irradiated with two doses of UV-B (10 and …
Potassium Ion Fluxes In Corneal Epithelial Cells Exposed To Uvb, John L. Ubels, Rachel E. Van Dyken, Julienne R. Louters, Mark P. Schotanus
Potassium Ion Fluxes In Corneal Epithelial Cells Exposed To Uvb, John L. Ubels, Rachel E. Van Dyken, Julienne R. Louters, Mark P. Schotanus
University Faculty Publications and Creative Works
The goal of this study was to investigate the efflux of K+ from human corneal limbal epithelial cells (HCLE) exposed to ambient levels of UVB, which is known to cause apoptosis, and to examine the effect of K+ channel blockers on loss of potassium induced by UVB. HCLE cells were exposed to 100-200 mJ/cm2 UVB, followed by incubation in culture media with 5.5-100 mM K+, BDS-1, Ba2+ or ouabain. To measure intracellular cations, cells were washed in 280 mM sucrose and lysed in DI water. K+ and Na+ levels in lysates were measured by ion chromatography. HCLE cells showed maximal …
Potassium Ion Fluxes In Corneal Epithelial Cells Exposed To Uvb, John L. Ubels, Rachel E. Van Dyken, Julienne R. Louters, Mark P. Schotanus
Potassium Ion Fluxes In Corneal Epithelial Cells Exposed To Uvb, John L. Ubels, Rachel E. Van Dyken, Julienne R. Louters, Mark P. Schotanus
University Faculty Publications and Creative Works
The goal of this study was to investigate the efflux of K+ from human corneal limbal epithelial cells (HCLE) exposed to ambient levels of UVB, which is known to cause apoptosis, and to examine the effect of K+ channel blockers on loss of potassium induced by UVB. HCLE cells were exposed to 100-200 mJ/cm2 UVB, followed by incubation in culture media with 5.5-100 mM K+, BDS-1, Ba2+ or ouabain. To measure intracellular cations, cells were washed in 280 mM sucrose and lysed in DI water. K+ and Na+ levels in lysates were measured by ion chromatography. HCLE cells showed maximal …
Recollision Dynamics And Time Delay In Strong-Field Double Ionization, Stanley L. Haan, L. Breen, A. Karim, Joseph H. Eberly
Recollision Dynamics And Time Delay In Strong-Field Double Ionization, Stanley L. Haan, L. Breen, A. Karim, Joseph H. Eberly
University Faculty Publications and Creative Works
Three-dimensional classical ensembles are employed to study recollision dynamics in double ionization of atoms by 780-nm intense lasers. After recollision one electron typically remains bound to the atom for a portion of a laser cycle, during which time the nucleus strongly influences its direction of motion. The electron then escapes over a suppressed barrier, with its final momentum depending critically on the laser phase at escape. The other electron remains unbound after collision, and typically drifts out in a momentum hemisphere opposite from its motion just after the collision. Several example trajectories at intensity 0.4 PW/cm2 with various time delays …
Cornea, Carnap, And Current Closure Befuddlement, Stephen J. Wykstra
Cornea, Carnap, And Current Closure Befuddlement, Stephen J. Wykstra
University Faculty Publications and Creative Works
Graham and Maitzen think my CORNEA principle is in trouble because it entails "intolerable violations of closure under known entailment." I argue that the trouble arises from current befuddlement about closure itself, and that a distinction drawn by Rudolph Carnap, suitably extended, shows how closure, when properly understood, works in tandem with CORNEA. CORNEA does not obey Closure because it shouldn't: it applies to "dynamic" epistemic operators, whereas closure principles hold only for "static" ones. What the authors see as an intolerable vice of CORNEA is actually a virtue, helping us see what closure principles should-and shouldn't-themselves be about.
Speed-Up Collisions In Strong-Field Double Ionization, Stanley L. Haan, J. C. Cully, K. Hoekema
Speed-Up Collisions In Strong-Field Double Ionization, Stanley L. Haan, J. C. Cully, K. Hoekema
University Faculty Publications and Creative Works
We compare quantum and classical models of double ionization (DI) for aligned-electron helium in strong laser fields, considering specifically the role of recollision processes in which the returning electron travels in the direction of the laser force. Quantum studies show that for the knee region in our model a small but persistent portion of the total DI occurs through these speed-up collisions. We show that classical modeling displays similar collisions and reveals that with-the-force doubly ionizing collisions typically involve two-particle trajectories in which both electrons can be said to have been bound or very nearly bound at the zero of …
Comparing Classical And Quantum Dynamics Of Strong-Field Double Ionization, R. Panfili, J. H. Eberly, Stanley L. Haan
Comparing Classical And Quantum Dynamics Of Strong-Field Double Ionization, R. Panfili, J. H. Eberly, Stanley L. Haan
University Faculty Publications and Creative Works
We compare quantum mechanical and fully classical treatments of electron dynamics accompanying strong field double ionization. The major features seen in quantum mechanical simulations, including the double-ionization jets, are reproduced when using a classical ensemble of two-particle trajectories.
Directional Correlation In Direct And Sequential Double Ionization Of Model Atoms, Stanley L. Haan, N. Hoekema, S. Poniatowski, W. C. Liu
Directional Correlation In Direct And Sequential Double Ionization Of Model Atoms, Stanley L. Haan, N. Hoekema, S. Poniatowski, W. C. Liu
University Faculty Publications and Creative Works
We discuss directional dependence in the time development of spatial wavefunctions, which includes jet formation, for two-electron model atoms exposed to intense laser fields. Two competing scenarios for double ionization are evident: (1) both electrons emerge simultaneously from the core region and on the same side of the nucleus, and (2) the electrons detach on opposite sides but not simultaneously. The importance of the electron-electron repulsion contribution to the competing processes is investigated for various laser intensities.