4,158 research outputs found
The Effect of Neutral Atoms on Capillary Discharge Z-pinch
We study the effect of neutral atoms on the dynamics of a capillary discharge
Z-pinch, in a regime for which a large soft-x-ray amplification has been
demonstrated. We extended the commonly used one-fluid magneto-hydrodynamics
(MHD) model by separating out the neutral atoms as a second fluid. Numerical
calculations using this extended model yield new predictions for the dynamics
of the pinch collapse, and better agreement with known measured data.Comment: 4 pages, 4 postscript figures, to be published in Phys. Rev. Let
Hybridly pumped collisional soft X-ray laser in Ne-like sulphur
Includes bibliographical references (page 98).We describe an experiment demonstrating XUV amplification following collisional excitation in a discharge-created plasma waveguide irradiated by a picosecond optical laser pulse. A capillary discharge was used to generate a plasma radiation pipe with a radially concave electron density profile. Temporally resolved transmission characteristics and guiding effect have been measured. An intense short laser pulse rapidly heated the electrons, producing amplification in the 3p1S0-3s 1P1 transition of Ne-like S at 60.84 nm. The integrated gain-length product obtained within a 3 cm active medium with a laser energy of 0.46 J was ~6.8. The pump energy depletion has been analysed as well. This new, hybridly pumped soft X-ray laser with the transient gain offers a new way towards efficient tabletop coherent XUV sources
A Deep Multicolor Survey. VI. Near-Infrared Observations, Selection Effects, and Number Counts
I present near-infrared J (1.25um), H (1.65um), and K (2.2um) imaging
observations of 185 square arcminutes in 21 high galactic latitude fields.
These observations reach limiting magnitudes of J ~ 21 mag, H ~ 20 mag and K ~
18.5 mag. The detection efficiency, photometric accuracy and selection biases
as a function of integrated object brightness, size, and profile shape are
quantified in detail. I evaluate several popular methods for measuring the
integrated light of faint galaxies and show that only aperture magnitudes
provide an unbiased measure of the integrated light that is independent of
apparent magnitude. These J, H, and K counts and near-infrared colors are in
best agreement with passive galaxy formation models with at most a small amount
of merging (for Omega_M = 0.3, Omega_Lambda = 0.7).Comment: AJ Accepted (Feb 2001). 28 pages, 7 embedded ps figures, AASTEX5.
Minor changes to submitted version. Also available at
http://www.astronomy.ohio-state.edu/~martini/pubs
Dense plasma diagnostics with an amplitude-division soft-x-ray laser interferometer based on diffraction gratings
Includes bibliographical references (page 358).We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma
Dense plasma interferometry with a tabletop soft X-ray laser and an amplitude division interferometer based on diffraction gratings
Includes bibliographical references (page 486).We have demonstrated a novel Mach-Zehnder soft x-ray interferometer that uses diffraction gratings as beam splitters. The interferometer was used together with a 46.9nm tabletop soft x-ray laser, to map the evolution of the electron density distribution of a large-scale laser created plasma
Adiponectin and Sarcopenia: A Systematic Review With Meta-Analysis
Background: Sarcopenia is a progressive loss of skeletal muscle mass whose pathophysiology has been proposed to possibly involve mechanisms of altered inflammatory status and endocrine function. Adiponectin has been shown to modulate inflammatory status and muscle metabolism. However, the possible association between adiponectin levels and sarcopenia is poorly understood. In order to fill this gap, in the present manuscript we aimed to summarize the current evidence with a systematic review and a meta-analysis of studies reporting serum adiponectin levels in patients with sarcopenia compared to non-sarcopenic controls. Methods: An electronic search through Medline/PubMed, Cochrane Library, and Science Direct was performed till March 1, 2020. From the included papers, meta-analysis of cross-sectional studies comparing serum levels of adiponectin between patients with sarcopenia and controls was performed. Results: Out of 1,370 initial studies, seven studies were meta-analyzed. Sarcopenic participants had significantly higher levels of adiponectin Hedges’ g with 95% confidence interval (CI): 1.20 (0.19–2.22), p = 0.02 than controls. Subgroup analysis, performed in Asian population and focused on identification of the condition based on AWGS criteria, reported higher adiponectin levels in sarcopenic population (2.1 (0.17–4.03), p = 0.03 and I2 = 98.98%. Meta-regression analysis revealed female gender to significantly influence the results as demonstrated by beta = 0.14 (95% CI (0.010–0.280), p = 0.040). Conclusions: Our meta-analysis found evidence that sarcopenia is associated with higher adiponectin levels. However, caution is warranted on the interpretation of these findings, and future longitudinal research is required to disentangle and better understand the topic
Cross-Phase Modulation and Population Redistribution in a Periodic Tripod Medium
The cross-Kerr effect is studied for two pulses propagating in an atomic
medium in a tripod configuration, dressed by a strong standing wave coupling
beam. Nonlinear phase shifts for both transmitted and reflected beams are
calculated taking into account the redistribution of the population among the
atomic levels which allows one to study the phase shifts in a wide range of
pulse detunings. The influence of other parameters, e.g., the intensity of the
control field and the relaxation rates, on the cross-Kerr effect is also
examined in detail.Comment: 6 figure
Ablation of Submicrometer Holes Using an Extreme-Ultraviolet Laser
Simulations and experiments are used to study extreme-ultraviolet (EUV) laser drilling of submicrometer holes. The ablation process is studied with a 2D Eulerian hydrodynamic code that includes bound-free absorption processes relevant to the interaction of EUV lasers with a solid material. Good agreement is observed between the simulated and measured ablated depths for on-target irradiances of up to 1×1010  W cm−2. An increase in the irradiance to 1×1012  W cm−2 is predicted to ablate material to a depth of 3.8  μm from a single pulse with a hole diameter 3 to 4 times larger than the focal spot size. The model allows for the simulation of the interaction of a laser pulse with the crater created by a previous shot. Multiple-pulse lower-fluence irradiation configurations under optimized focusing conditions, i.e., approaching the diffraction limit, are shown to be advantageous for applications requiring mesoscale [(100  nm)–(1  μm)] features and a high level of control over the ablation profile
Soft-x-ray laser interferometry of a pinch discharge using a tabletop laser
Includes bibliographical references (page 917).We have used a tabletop soft-x-ray laser and a wave-front division interferometer to probe the plasma of a pinch discharge. A very compact capillary discharge-pumped Ne-like Ar laser emitting at 46.9 nm was combined with a wave division interferometer based on Lloyd's mirror and Sc-Si multilayer-coated optics to map the electron density in the cathode region of the discharge. This demonstration of the use of tabletop soft-x-ray laser in plasma interferometry could lead to the widespread use of these lasers in the diagnostics of dense plasmas
Silicon nitride films deposited with an electron beam created plasma
Includes bibliographical references (page 600).Silicon nitride films have been deposited using an electron beam created plasma in a silane, ammonia, and nitrogen mixture. The films were deposited at substrate temperatures between 50 and 400 °C. Physical, chemical, and electrical properties of these films are reported
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