7,489 research outputs found
The Effect of Testosterone Administration on Physical Characteristics and Muscle Function in Men with Low to Low-Normal Testosterone Concentrations
Objective: This meta-analysis uses data from clincial studies of older men with low to low-normal concentrations of testosterone (T) that were treated with exogenous T to assess treatment efficacy on: lean body mass, fat mass, strength, and mobility. Methods: The data investigated are from published and referred journals. The Cohen\u27s d was used to compute effect sizes from both pre-treatment and post-treatment scores. Results: The analysis revealed that T resulted in an overall significant (p = 0.037) improvement in physical characteristics and muscle function. After accounting for the variance, significance wa strengthened (p = 0.006) for the overall effect. When the dependent variables were considered independently, the largest contribution came from a decreases in fat mass (p = 0.003), followed by a non-significant trend (p = 0.06) for an increase in lean mass. After accounting for the variance for the dependent variables independently, lean mass (p = 0.0003), fat mass (p = 0.005), and strength (p = 0.02) were all found to be signifianct contributors. Conclusion: T administration can be considereda viable treatment for both the prevention and rehabilitation of decreased muscle mass and muscle strength seen in older men with low to low-normal T concentrations
A NASTRAN primer for the analysis of rotating flexible blades
This primer provides documentation for using MSC NASTRAN in analyzing rotating flexible blades. The analysis of these blades includes geometrically nonlinear (large displacement) analysis under centrifugal loading, and frequency and mode shape (normal modes) determination. The geometrically nonlinear analysis using NASTRAN Solution sequence 64 is discussed along with the determination of frequencies and mode shapes using Solution Sequence 63. A sample problem with the complete NASTRAN input data is included. Items unique to rotating blade analyses, such as setting angle and centrifugal softening effects are emphasized
Systems biology of energetic and atomic costs in the yeast transcriptome, proteome, and metabolome
Proteins vary in their cost to the cell and natural selection may favour the use of proteins that are cheaper to produce. We develop a novel approach to estimate the amino acid biosynthetic cost based on genome-scale metabolic models, and directly investigate the effects of biosynthetic cost on transcriptomic, proteomic and metabolomic data in _Saccharomyces cerevisiae_. We find that our systems approach to formulating biosynthetic cost produces a novel measure that explains similar levels of variation in gene expression compared with previously reported cost measures. Regardless of the measure used, the cost of amino acid synthesis is weakly associated with transcript and protein levels, independent of codon usage bias. In contrast, energetic costs explain a large proportion of variation in levels of free amino acids. In the economy of the yeast cell, there appears to be no single currency to compute the cost of amino acid synthesis, and thus a systems approach is necessary to uncover the full effects of amino acid biosynthetic cost in complex biological systems that vary with cellular and environmental conditions
Solid-state ensemble of highly entangled photon sources at rubidium atomic transitions
Semiconductor InAs/GaAs quantum dots grown by the Stranski-Krastanov method
are among the leading candidates for the deterministic generation of
polarization entangled photon pairs. Despite remarkable progress in the last
twenty years, many challenges still remain for this material, such as the
extremely low yield (<1% quantum dots can emit entangled photons), the low
degree of entanglement, and the large wavelength distribution. Here we show
that, with an emerging family of GaAs/AlGaAs quantum dots grown by droplet
etching and nanohole infilling, it is possible to obtain a large ensemble
(close to 100%) of polarization-entangled photon emitters on a wafer without
any post-growth tuning. Under pulsed resonant two-photon excitation, all
measured quantum dots emit single pairs of entangled photons with ultra-high
purity, high degree of entanglement (fidelity up to F=0.91, with a record high
concurrence C=0.90), and ultra-narrow wavelength distribution at rubidium
transitions. Therefore, a solid-state quantum repeater - among many other key
enabling quantum photonic elements - can be practically implemented with this
new material
Pion scattering in Wilson ChPT
We compute the scattering amplitude for pion scattering in Wilson chiral
perturbation theory for two degenerate quark flavors. We consider two different
regimes where the quark mass m is of order (i) a\Lambda_QCD^2 and (ii)
a^2\Lambda_QCD^3. Analytic expressions for the scattering lengths in all three
isospin channels are given. As a result of the O(a^2) terms the I=0 and I=2
scattering lengths do not vanish in the chiral limit. Moreover, additional
chiral logarithms proportional to a^2\ln M_{\pi}^2 are present in the one-loop
results for regime (ii). These contributions significantly modify the familiar
results from continuum chiral perturbation theory.Comment: 20 pages, 4 figures. V3: Comments on finite size effects and the
axial vector current added, one more reference. To be published in PR
The Use of Engineered Voltage-Sensing Phosphatases to Study the Determinants of Substrate Specificity of Phosphoinositide Phosphatases
A critical and Integrated View of the Yeast Interactome
Global studies of proteināprotein interactions are crucial to both elucidating gene
function and producing an integrated view of the workings of living cells. High-throughput
studies of the yeast interactome have been performed using both genetic
and biochemical screens. Despite their size, the overlap between these experimental
datasets is very limited. This could be due to each approach sampling only a small
fraction of the total interactome. Alternatively, a large proportion of the data from
these screens may represent false-positive interactions. We have used the Genome
Information Management System (GIMS) to integrate interactome datasets with
transcriptome and protein annotation data and have found significant evidence that
the proportion of false-positive results is high. Not all high-throughput datasets are
similarly contaminated, and the tandem affinity purification (TAP) approach appears
to yield a high proportion of reliable interactions for which corroborating evidence
is available. From our integrative analyses, we have generated a set of verified
interactome data for yeast
UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol::Competition between C-Y (Y = halogen) and O-H bond fission
Protected gates for topological quantum field theories
We study restrictions on locality-preserving unitary logical gates for
topological quantum codes in two spatial dimensions. A locality-preserving
operation is one which maps local operators to local operators --- for example,
a constant-depth quantum circuit of geometrically local gates, or evolution for
a constant time governed by a geometrically-local bounded-strength Hamiltonian.
Locality-preserving logical gates of topological codes are intrinsically fault
tolerant because spatially localized errors remain localized, and hence
sufficiently dilute errors remain correctable. By invoking general properties
of two-dimensional topological field theories, we find that the
locality-preserving logical gates are severely limited for codes which admit
non-abelian anyons; in particular, there are no locality-preserving logical
gates on the torus or the sphere with M punctures if the braiding of anyons is
computationally universal. Furthermore, for Ising anyons on the M-punctured
sphere, locality-preserving gates must be elements of the logical Pauli group.
We derive these results by relating logical gates of a topological code to
automorphisms of the Verlinde algebra of the corresponding anyon model, and by
requiring the logical gates to be compatible with basis changes in the logical
Hilbert space arising from local F-moves and the mapping class group.Comment: 50 pages, many figures, v3: updated to match published versio
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