1,692 research outputs found
Effect of Caffeine Ingestion on Indirect Markers of Exercise-Induced Muscle Damage: A Systematic Review of Human Trials
The effect of caffeine on mitigating exercise-induced muscle damage (EIMD) is still poorly understood, but it was hypothesized that caffeine could contribute to decreasing delayed onset muscle soreness, attenuating temporary loss of strength, and reducing circulating levels of blood markers of muscle damage. However, evidence is not conclusive and beneficial effects of caffeine ingestion on EIMD are not always observed. Factors, such as the type of exercise that induces muscle damage, supplementation protocol, and type of marker analyzed contribute to the differences between the studies. To expand knowledge on the role of caffeine supplementation in EIMD, this systematic review aimed to investigate the effect of caffeine supplementation on different markers of muscle damage. Fourteen studies were included, evaluating the effect of caffeine on indirect muscle damage markers, including blood markers (nine studies), pain perception (six studies), and MVC maximal voluntary contraction force (four studies). It was observed in four studies that repeated administration of caffeine between 24 and 72 h after muscle damage can attenuate the perception of pain in magnitudes ranging from 3.9% to 26%. The use of a single dose of caffeine pre-exercise (five studies) or post-exercise (one study) did not alter the circulating blood levels of creatine kinase (CK). Caffeine supplementation appears to attenuate pain perception, but this does not appear to be related to an attenuation of EIMD, per se. Furthermore, the effect of caffeine supplementation after muscle damage on strength recovery remains inconclusive due to the low number of studies found (four studies) and controversial results for both dynamic and isometric strength tests
Differentially Testing Soundness and Precision of Program Analyzers
In the last decades, numerous program analyzers have been developed both by
academia and industry. Despite their abundance however, there is currently no
systematic way of comparing the effectiveness of different analyzers on
arbitrary code. In this paper, we present the first automated technique for
differentially testing soundness and precision of program analyzers. We used
our technique to compare six mature, state-of-the art analyzers on tens of
thousands of automatically generated benchmarks. Our technique detected
soundness and precision issues in most analyzers, and we evaluated the
implications of these issues to both designers and users of program analyzers
Geometry of Frictionless and Frictional Sphere Packings
We study static packings of frictionless and frictional spheres in three
dimensions, obtained via molecular dynamics simulations, in which we vary
particle hardness, friction coefficient, and coefficient of restitution.
Although frictionless packings of hard-spheres are always isostatic (with six
contacts) regardless of construction history and restitution coefficient,
frictional packings achieve a multitude of hyperstatic packings that depend on
system parameters and construction history. Instead of immediately dropping to
four, the coordination number reduces smoothly from as the friction
coefficient between two particles is increased.Comment: 6 pages, 9 figures, submitted to Phys. Rev.
Low Metallicity Galaxies from the Dark Energy Survey
We present a new selection of 358 blue compact dwarf galaxies (BCDs) from
5,000 square degrees in the Dark Energy Survey (DES), and the spectroscopic
follow-up of a subsample of 68 objects. For the subsample of 34 objects with
deep spectra, we measure the metallicity via the direct T method using the
auroral [\oiii] 4363 emission line. These BCDs have average oxygen
abundance of 12+log(O/H)= 7.8, stellar masses between 10 to 10
M and specific SFR between 10 to 10 yr. We
compare the position of our BCDs with the Mass-metallicity (M-Z) and
Luminosity-metallicity (L-Z) relation derived from the Local Volume Legacy
sample. We find the scatter around the M-Z relation is smaller than the scatter
around the L-Z relation. We identify a correlation between the offsets from the
M-Z and L-Z relation that we suggest is due to the contribution of metal-poor
inflows. Finally, we explore the validity of the mass-metallicity-SFR
fundamental plane in the mass range probed by our galaxies. We find that BCDs
with stellar masses smaller than M do not follow the
extrapolation of the fundamental plane. This result suggests that mechanisms
other than the balance between inflows and outflows may be at play in
regulating the position of low mass galaxies in the M-Z-SFR space.Comment: 16 pages, 10 figures, submitted to ApJ, We invite comments from the
communit
Molecular characterization of the human COQ5 C-methyltransferase in coenzyme Q10 biosynthesis
Under a Creative Commons license.Coq5 catalyzes the only C-methylation involved in the biosynthesis of coenzyme Q (Q or ubiquinone) in humans and yeast Saccharomyces cerevisiae. As one of eleven polypeptides required for Q production in yeast, Coq5 has also been shown to assemble with the multi-subunit complex termed the CoQ-synthome. In humans, mutations in several COQ genes cause primary Q deficiency, and a decrease in Q biosynthesis is associated with mitochondrial, cardiovascular, kidney and neurodegenerative diseases. In this study, we characterize the human COQ5 polypeptide and examine its complementation of yeast coq5 point and null mutants. We show that human COQ5 RNA is expressed in all tissues and that the COQ5 polypeptide is associated with the mitochondrial inner membrane on the matrix side. Previous work in yeast has shown that point mutations within or adjacent to conserved COQ5 methyltransferase motifs result in a loss of Coq5 function but not Coq5 steady state levels. Here, we show that stabilization of the CoQ-synthome within coq5 point mutants or by over-expression of COQ8 in coq5 null mutants permits the human COQ5 homolog to partially restore coq5 mutant growth on respiratory media and Q6 content. Immunoblotting against the human COQ5 polypeptide in isolated yeast mitochondria shows that the human Coq5 polypeptide migrates in two-dimensional blue-native/SDS-PAGE at the same high molecular mass as other yeast Coq proteins. The results presented suggest that human and Escherichia coli Coq5 homologs expressed in yeast retain C-methyltransferase activity but are capable of rescuing the coq5 yeast mutants only when the CoQ-synthome is assembled.Open Access funded by Telethon (Italy).Peer Reviewe
Resolved images of self-gravitating circumstellar discs with ALMA
In this paper we present simulated observations of massive self-gravitating
circumstellar discs using the Atacama Large Millimetre/sub-millimetre Array
(ALMA). Using a smoothed particle hydrodynamics model of a disc
orbiting a protostar, with a cooling model appropriate for discs
at temperatures below K and representative dust opacities, we have
constructed maps of the expected emission at sub-mm wavelengths. We have then
used the CASA ALMA simulator to generate simulated images and visibilities with
various array configurations and observation frequencies, taking into account
the expected thermal noise and atmospheric opacities. We find that at 345 GHz
(870 m) spiral structures at a resolution of a few AU should be readily
detectable in approximately face-on discs out to distances of the Taurus-Auriga
star-forming complex.Comment: 8 pages, 6 figures, accepted to MNRAS. Figure quality degraded. Full
paper with higher quality figures available at
http://www2.fisica.unimi.it/lodato/CossinsLodatoTesti1.pd
Radio multiwavelength analysis of the compact disk CX Tau: strong free-free variability or anomalous microwave emission?
Protoplanetary disks emit radiation across a broad range of wavelengths,
requiring a multiwavelength approach to fully understand their physical
mechanisms and how they form planets. Observations at sub-millimeter to
centimeter wavelengths can provide insights into the thermal emission from
dust, free-free emission from ionized gas, and possible gyro-synchrotron
emission from the stellar magnetosphere. This Letter focuses on CX Tau, a
star with an extended gas emission and a compact and
apparently structureless dust disk, with an average millimeter flux when
compared to Class II sources in Taurus. We present Karl G. Jansky Very Large
Array (VLA) observations in 4 bands (between 9.0 mm and 6.0 cm) and combine
them with archival data from the Atacama Large Millimeter/submillimeter Array
(ALMA), the Submillimeter Array (SMA) and the Plateau de Bure Interferometer
(PdBI). Such a multiwavelength approach allows to separate the dust continuum
from other emissions. After isolating the dust thermal emission, we derived an
upper limit of the dust disk extent at 1.3 cm which is consistent with
theoretical predictions of a radial drift-dominated disk. Centimeter data show
a peculiar behavior: deep observations at 6.0 cm did not detect the source,
while at 1.3 cm the flux density is anomalously higher than adjacent bands.
Intraband spectral indices suggest a dominant contribution from free-free
emission, whereas gyro-synchrotron emission is excluded. To explain these
observations, we propose strong variability of the free-free emission with
timescales shorter than a month. Another possible interpretation is the
presence of anomalous microwave emission from spinning dust grains.Comment: Accepted for publication in A&A Letters; 13 pages, 13 figures, 1
tabl
Understanding The Impact of Solver Choice in Model-Based Test Generation
Background: In model-based test generation, SMT solvers explore the state-space of the model in search of violations of specified properties. If the solver finds that a predicate can be violated, it produces a partial test specification demonstrating the violation.Aims: The choice of solvers is important, as each may produce differing counterexamples. We aim to understand how solver choice impacts the effectiveness of generated test suites at finding faults.Method: We have performed experiments examining the impact of solver choice across multiple dimensions, examining the ability to attain goal satisfaction and fault detection when satisfaction is achieved---varying the source of test goals, data types of model input, and test oracle.Results: The results of our experiment show that solvers vary in their ability to produce counterexamples, and---for models where all solvers achieve goal satisfaction---in the resulting fault detection of the generated test suites. The choice of solver has an impact on the resulting test suite, regardless of the oracle, model structure, or source of testing goals.Conclusions: The results of this study identify factors that impact fault-detection effectiveness, and advice that could improve future approaches to model-based test generation
Statistics of the contact network in frictional and frictionless granular packings
Simulated granular packings with different particle friction coefficient mu
are examined. The distribution of the particle-particle and particle-wall
normal and tangential contact forces P(f) are computed and compared with
existing experimental data. Here f equivalent to F/F-bar is the contact force F
normalized by the average value F-bar. P(f) exhibits exponential-like decay at
large forces, a plateau/peak near f = 1, with additional features at forces
smaller than the average that depend on mu. Computations of the force-force
spatial distribution function and the contact point radial distribution
function indicate that correlations between forces are only weakly dependent on
friction and decay rapidly beyond approximately three particle diameters.
Distributions of the particle-particle contact angles show that the contact
network is not isotropic and only weakly dependent on friction. High
force-bearing structures, or force chains, do not play a dominant role in these
three dimensional, unloaded packings.Comment: 11 pages, 13 figures, submitted to PR
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