1,189 research outputs found
Uterine Prolapse in an Adult Richardson's Ground Squirrel, Spermophilus richardsonii
During a study of Richardson's Ground Squirrel (Spermophilus richardsonii) populations in southern Saskatchewan, we captured one adult female with a partially prolapsed uterus. This is the first known case of uterine prolapse in a Richardson's Ground Squirrel
The transition of GTDS to the Unix workstation environment
Future Flight Dynamics systems should take advantage of the possibilities provided by current and future generations of low-cost, high performance workstation computing environments with Graphical User Interface. The port of the existing mainframe Flight Dynamics systems to the workstation environment offers an economic approach for combining the tremendous engineering heritage that has been encapsulated in these systems with the advantages of the new computing environments. This paper will describe the successful transition of the Draper Laboratory R&D version of GTDS (Goddard Trajectory Determination System) from the IBM Mainframe to the Unix workstation environment. The approach will be a mix of historical timeline notes, descriptions of the technical problems overcome, and descriptions of associated SQA (software quality assurance) issues
Restoration of mitochondrial integrity, telomere length, and sensitivity to oxidation by in vitro culture of Fuchs’ endothelial corneal dystrophy cells
PURPOSE. Fuchs’ endothelial corneal dystrophy (FECD), a degenerative disease of the corneal
endothelium that leads to vision loss, is a leading cause of corneal transplantation. The cause
of this disease is still unknown, but the implication of oxidative stress is strongly suggested. In
this study, we analyzed the impact of FECD on mitochondrial DNA (mtDNA) integrity and
telomere length, both of which are affected by the oxidative status of the cell.
METHODS. We compared the levels of total mtDNA, mtDNA common deletion (4977 bp), and
relative telomere length in the corneal endothelial cells of fresh Descemet’s membraneendothelium explants and cultured cells from healthy and late stage FECD subjects. Oxidantantioxidant gene expression and sensitivity to ultraviolet A (UVA)- and H2O2-induced cell
death were assessed in cultured cells.
RESULTS. Our results revealed increased mtDNA levels and telomere shortening in FECD
explants. We also found that cell culture restores a normal phenotype in terms of mtDNA
levels, telomere length, oxidant-antioxidant gene expression balance, and sensitivity to
oxidative stress-induced cell death in the FECD cells compared with the healthy cells.
CONCLUSIONS. Taken together, these results bring new evidence of the implication of oxidative
stress in FECD. They also show that FECD does not evenly affect the integrity of corneal
endothelial cells and that cell culture can rehabilitate the molecular phenotypes related to
oxidative stress by selecting the more functional FECD cells
Separation and identification of dominant mechanisms in double photoionization
Double photoionization by a single photon is often discussed in terms of two
contributing mechanisms, {\it knock-out} (two-step-one) and {\it shake-off}
with the latter being a pure quantum effect. It is shown that a quasi-classical
description of knock-out and a simple quantum calculation of shake-off provides
a clear separation of the mechanisms and facilitates their calculation
considerably. The relevance of each mechanism at different photon energies is
quantified for helium. Photoionization ratios, integral and singly differential
cross sections obtained by us are in excellent agreement with benchmark
experimental data and recent theoretical results.Comment: 4 pages, 5 figure
Scaling and commensurate-incommensurate crossover for the d=2, z=2 quantum critical point of itinerant antiferromagnets
Quantum critical points exist at zero temperature, yet, experimentally their
influence seems to extend over a large part of the phase diagram of systems
such as heavy-fermion compounds and high-temperature superconductors.
Theoretically, however, it is generally not known over what range of parameters
the physics is governed by the quantum critical point. We answer this question
for the spin-density wave to fermi-liquid quantum critical point in the
two-dimensional Hubbard model. This problem is in the universality
class. We use the Two-Particle Self-Consistent approach, which is accurate from
weak to intermediate coupling, and whose critical behavior is the same as for
the self-consistent-renormalized approach of Moriya. Despite the presence of
logarithmic corrections, numerical results demonstrate that quantum critical
scaling for the static magnetic susceptibility can extend up to very high
temperatures but that the commensurate to incommensurate crossover leads to
deviations to scaling.Comment: Unchanged numerical results. It is now shown analytically that the
approach includes logarithmic corrections and that the critical behavior is
equivalent to the theory of Moriya. 6 pages, 3 figures, Late
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