1,354 research outputs found
Non cell autonomous upregulation of CDKN2 transcription linked to progression of chronic hepatitis C disease
Chronic hepatitis C virus infection (C-HC) is associated with higher mortality arising from hepatic and extrahepatic disease. This may be due to accelerated biological aging; however, studies in C-HC have thus far been based solely on telomere length as a biomarker of aging (BoA). In this study, we have evaluated CDKN2 locus transcripts as alternative BoAs in C-HC. Our results suggest that C-HC induces non-cell-autonomous senescence and accelerates biological aging. The CDKN2 locus may provide a link between C-HC and increased susceptibility to age-associated diseases and provides novel biomarkers for assessing its impact on aging processes in man
3d absorption-spectra of Sr I through Sr IV
The extreme ultraviolet photoabsorption spectra of neutral to three-times-ionized strontium have been recorded in a comprehensive series of experiments with the dual laser-produced plasma technique. Striking differences were found in the spectra, which can be attributed to the transfer of oscillator strength from 3d→np to 3d→nf transitions at Sr2+ due to nf wave-function contraction. In Sr and Sr+, 3d→5p transitions dominate; in Sr2+, 3d→nf transitions are most intense, while in Sr3+ the 4p subshell opens and 3d→4p transitions are the strongest features. Partial cross sections for 3d→ɛf and 3d→ɛp photoionization were calculated and compared with experiment
An angle-resolved soft x-ray spectroscopy study of the electronic states of single crystal MgB2
Angle-resolved soft x-ray measurements made at the boron K-edge in single
crystal MgB2 provide new insights into the B-2p local partial density of both
unoccupied and occupied band states. The strong variation of absorption with
incident angle of exciting x-rays permits the clear separation of contributions
from \sigma states in the boron plane and \pi states normal to the plane. A
careful comparison with theory accurately determines the energy of selected
critical points in the conduction band. Resonant inelastic x-ray emission
at an incident angle of 15 degrees shows a large enhancement of the emission
spectra within about 0.5 eV of the Fermi level that is absent at 45 degrees and
is much reduced at 60 degrees. We conclude that momentum transferred from the
resonant inelastic x-ray scattering (RIXS) process couples empty and filled
states across the Fermi level.Comment: Accepted to PRB. 13 pages, 6 figure
Integrated optical addressing of a trapped ytterbium ion
We report on the characterization of heating rates and photo-induced electric
charging on a microfabricated surface ion trap with integrated waveguides.
Microfabricated surface ion traps have received considerable attention as a
quantum information platform due to their scalability and manufacturability.
Here we characterize the delivery of 435 nm light through waveguides and
diffractive couplers to a single ytterbium ion in a compact trap. We measure an
axial heating rate at room temperature of q/ms and see no
increase due to the presence of the waveguide. Furthermore, the electric field
due to charging of the exposed dielectric outcoupler settles under normal
operation after an initial shift. The frequency instability after settling is
measured to be 0.9 kHz.Comment: 7 pages, 8 figure
Helping education undergraduates to use appropriate criteria for evaluating accounts of motivation
The aim of the study was to compare students in a control group with those in a treatment group with respect to evaluative comments on psychological accounts of motivation. The treatment group systematically scrutinized the nature and interpretation of evidence that supported different accounts, and the assumptions, logic, coherence and clarity of accounts. Content analysis of 74 scripts (using three categories) showed that the control group students made more assertions than either evidential or evaluative points, whereas the treatment group used evaluative statements as often as they used assertion. The findings provide support for privileging activities that develop understanding of how knowledge might be contested, and suggest a need for further research on pedagogies to serve this end. The idea is considered that such understanding has a pivotal role in the development of critical thinking
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Correlating Pulses from Two Spitfire, 800nm Lasers
The E163 laser acceleration experiments conducted at SLAC have stringent requirements on the temporal properties of two regeneratively amplified, 800nm, Spitfire laser systems. To determine the magnitude and cause of timing instabilities between the two Ti:Sapphire amplifiers, we pass the two beams through a cross-correlator and focus the combined beam onto a Hamamatsu G1117 photodiode. The photodiode has a bandgap such that single photon processes are suppressed and only the second order, two-photon process produces an observable response. The response is proportional to the square of the intensity. The diode is also useful as a diagnostic to determine the optimal configuration of the compression cavity
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