675 research outputs found
Immune Function and Muscle Adaptations to Resistance exercise in Older Adults: Study Protocol for a Randomized Controlled Trial of a Nutritional Supplement
BACKGROUND: Immune function may influence the ability of older adults to maintain or improve muscle mass, strength, and function during aging. Thus, nutritional supplementation that supports the immune system could complement resistance exercise as an intervention for age-associated muscle loss. The current study will determine the relationship between immune function and exercise training outcomes for older adults who consume a nutritional supplement or placebo during resistance training and post-training follow-up. The supplement was chosen due to evidence suggesting its ingredients [arginine (Arg), glutamine (Gln), and β-hydroxy β-methylbutyrate (HMB)] can improve immune function, promote muscle growth, and counteract muscle loss.
METHODS/DESIGN: Veterans (age 60 to 80 yrs, N = 50) of the United States military will participate in a randomized double-blind placebo-controlled trial of consumption of a nutritional supplement or placebo during completion of three study objectives: 1) determine if 2 weeks of supplementation improve immune function measured as the response to vaccination and systemic and cellular responses to acute resistance exercise; 2) determine if supplementation during 36 sessions of resistance training boosts gains in muscle size, strength, and function; and 3) determine if continued supplementation for 26 weeks post-training promotes retention of training-induced gains in muscle size, strength, and function. Analyses of the results for these objectives will determine the relationship between immune function and the training outcomes. Participants will undergo nine blood draws and five muscle (vastus lateralis) biopsies so that the effects of the supplement on immune function and the systemic and cellular responses to exercise can be measured.
DISCUSSION: Exercise has known effects on immune function. However, the study will attempt to modulate immune function using a nutritional supplement and determine the effects on training outcomes. The study will also examine post-training benefit retention, an important issue for older adults, usually omitted from exercise studies. The study will potentially advance our understanding of the mechanisms of muscle gain and loss in older adults, but more importantly, a nutritional intervention will be evaluated as a complement to exercise for supporting muscle health during aging.
TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT02261961, registration date 10 June 2014, recruitment active
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High performance electromagnetic railgun launcher
A railgun operates at high pressure (up to 350 MPa) without structural damage and is readily disassembled for inspection, maintenance and component testing. A rail assembly is pressed into a hoop-wound epoxy fiberglass containment tube and clamped within a steel compression frame. The geometry of the rail assembly permits rail movement without insulator intrusion and achieves bore sealing during rail movement at maximum pressure. The rail assembly also has replaceable insulator inserts which are isolated from rail re-bound shock. Fused quartz insulator inserts provide the best results. A flash tube is provided at the gun muzzle to suppress precursor discharge and commutate precursor current back to the armature. To realize increased velocity without sacrificing in-bore projectile stability, a cut-corner projectile is used having a L/D ratio as small as 0.65 which reduces the mass by about 11%.Board of Regents, University of Texas Syste
What is a Cool-Core Cluster? A Detailed Analysis of the Cores of the X-ray Flux-Limited HIFLUGCS Cluster Sample
We use the largest complete sample of 64 galaxy clusters (HIghest X-ray FLUx
Galaxy Cluster Sample) with available high-quality X-ray data from Chandra, and
apply 16 cool-core diagnostics to them, some of them new. We also correlate
optical properties of brightest cluster galaxies (BCGs) with X-ray properties.
To segregate cool core and non-cool-core clusters, we find that central cooling
time, t_cool, is the best parameter for low redshift clusters with high quality
data, and that cuspiness is the best parameter for high redshift clusters. 72%
of clusters in our sample have a cool core (t_cool < 7.7 h_{71}^{-1/2} Gyr) and
44% have strong cool cores (t_cool <1.0 h_{71}^{-1/2} Gyr). For the first time
we show quantitatively that the discrepancy in classical and spectroscopic mass
deposition rates can not be explained with a recent formation of the cool
cores, demonstrating the need for a heating mechanism to explain the cooling
flow problem. [Abridged]Comment: 45 pages, 19 figures, 7 tables. Accepted for publication in A&A.
Contact Person: Rupal Mittal ([email protected]
Mitochondrial Data in Monocot Phylologenetics
Mitochondrial sequences are an important source of data in animal phylogenetics, equivalent in importance to plastid sequences in plants. However, in recent years plant systematists have begun exploring the mitochondrial genome as a source of phylogenetically useful characters. The plant mitochondrial genome is renowned for its variability in size, structure, and gene organization, but this need not be of concern for the application of sequence data in phylogenetics. However, the incorporation of reverse transcribed mitochondrial genes ( processed paralogs ) and the recurring transfer of genes from the mitochondrion to the nucleus are evolutionary events that must be taken into account. RNA editing of mitochondrial genes is sometimes considered a problem in phylogenetic reconstruction, but we regard it only as a mechanism that may increase variability at edited sites and change the codon position bias accordingly. Additionally, edited sites may prove a valuable tool in identifying processed paralogs. An overview of genes and sequences used in phylogenetic studies of angiosperms is presented. In the monocots, a large amount of mitochondrial sequence data is being collected together with sequence data from plastid and nuclear genes, thus offering an opportunity to compare data from different genomic compartments. The mitochondrial and plastid data are incongruent when organelle gene trees are reconstructed. Possible reasons for the observed incongruence involve sampling of paralogous sequences and highly divergent substitution rates, potentially leading to longbranch attraction. The above problems are addressed in Acorales, Alismatales, Poales, Liliaceae, the Anthericum clade (in Agavaceae), and in some achlorophyllous taxa
Alien Invasive Slider Turtle in Unpredicted Habitat: A Matter of Niche Shift or of Predictors Studied?
BACKGROUND: Species Distribution Models (SDMs) aim on the characterization of a species' ecological niche and project it into geographic space. The result is a map of the species' potential distribution, which is, for instance, helpful to predict the capability of alien invasive species. With regard to alien invasive species, recently several authors observed a mismatch between potential distributions of native and invasive ranges derived from SDMs and, as an explanation, ecological niche shift during biological invasion has been suggested. We studied the physiologically well known Slider turtle from North America which today is widely distributed over the globe and address the issue of ecological niche shift versus choice of ecological predictors used for model building, i.e., by deriving SDMs using multiple sets of climatic predictor. PRINCIPAL FINDINGS: In one SDM, predictors were used aiming to mirror the physiological limits of the Slider turtle. It was compared to numerous other models based on various sets of ecological predictors or predictors aiming at comprehensiveness. The SDM focusing on the study species' physiological limits depicts the target species' worldwide potential distribution better than any of the other approaches. CONCLUSION: These results suggest that a natural history-driven understanding is crucial in developing statistical models of ecological niches (as SDMs) while "comprehensive" or "standard" sets of ecological predictors may be of limited use
2-D Magnetohydrodynamic Simulations of Induced Plasma Dynamics in the Near-Core Region of a Galaxy Cluster
We present results from numerical simulations of the cooling-core cluster
A2199 produced by the two-dimensional (2-D) resistive magnetohydrodynamics
(MHD) code MACH2. In our simulations we explore the effect of anisotropic
thermal conduction on the energy balance of the system. The results from
idealized cases in 2-D axisymmetric geometry underscore the importance of the
initial plasma density in ICM simulations, especially the near-core values
since the radiation cooling rate is proportional to . Heat conduction
is found to be non-effective in preventing catastrophic cooling in this
cluster. In addition we performed 2-D planar MHD simulations starting from
initial conditions deliberately violating both thermal balance and hydrostatic
equilibrium in the ICM, to assess contributions of the convective terms in the
energy balance of the system against anisotropic thermal conduction. We find
that in this case work done by the pressure on the plasma can dominate the
early evolution of the internal energy over anisotropic thermal conduction in
the presence of subsonic flows, thereby reducing the impact of the magnetic
field. Deviations from hydrostatic equilibrium near the cluster core may be
associated with transient activity of a central active galactic nucleus and/or
remnant dynamical activity in the ICM and warrant further study in three
dimensions.Comment: 16 pages, 13 figures, accepted for publication in MNRA
Q^2 Dependence of the S_{11}(1535) Photocoupling and Evidence for a P-wave resonance in eta electroproduction
New cross sections for the reaction are reported for total
center of mass energy =1.5--2.3 GeV and invariant squared momentum transfer
=0.13--3.3 GeV. This large kinematic range allows extraction of new
information about response functions, photocouplings, and coupling
strengths of baryon resonances. A sharp structure is seen at 1.7 GeV.
The shape of the differential cross section is indicative of the presence of a
-wave resonance that persists to high . Improved values are derived for
the photon coupling amplitude for the (1535) resonance. The new data
greatly expands the range covered and an interpretation of all data with
a consistent parameterization is provided.Comment: 31 pages, 9 figure
Observation of an Exotic Baryon in Exclusive Photoproduction from the Deuteron
In an exclusive measurement of the reaction , a
narrow peak that can be attributed to an exotic baryon with strangeness
is seen in the invariant mass spectrum. The peak is at
GeV/c with a measured width of 0.021 GeV/c FWHM, which is largely
determined by experimental mass resolution. The statistical significance of the
peak is . The mass and width of the observed peak are
consistent with recent reports of a narrow baryon by other experimental
groups.Comment: 5 pages, 5 figure
Dependence of Quadrupole Strength in the Transition
Models of baryon structure predict a small quadrupole deformation of the
nucleon due to residual tensor forces between quarks or distortions from the
pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through
the dependence of the magnetic (), electric (), and
scalar () multipoles in the
transition. We report new experimental values for the ratios
and over the range = 0.4-1.8 GeV, extracted from
precision data using a truncated multipole expansion.
Results are best described by recent unitary models in which the pion cloud
plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett.
(References, figures and table updated, minor changes.
Measurement of the Polarized Structure Function for in the Resonance Region
The polarized longitudinal-transverse structure function
has been measured using the reaction in the
resonance region at and 0.65 GeV. No previous
data exist for this reaction channel. The kinematically
complete experiment was performed at Jefferson Lab with the CEBAF Large
Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an
energy of 1.515 GeV. A partial wave analysis of the data shows generally better
agreement with recent phenomenological models of pion electroproduction
compared to the previously measured channel. A fit to both
and channels using a unitary isobar model suggests the unitarized
Born terms provide a consistent description of the non-resonant background. The
-channel pion pole term is important in the channel through a
rescattering correction, which could be model-dependent.Comment: 6 pages, LaTex, 5 eps figures: Submitted to PRC/Brief Reports v2:
Updated referenc
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