405 research outputs found
The relationship of telomere length to baseline corticosterone levels in nestlings of an altricial passerine bird in natural populations
IndexaciĂłn: Web of Science; Scopus.Background: Environmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage. Modification of telomere length, as a result of adversity faced early in life, can modify an individual's phenotype. Studies in captivity have suggested a relationship between glucocorticoids and telomere length in developing individuals, however less is known about that relationship in natural populations.
Methods: In order to evaluate the effect of early environmental stressors on telomere length in natural populations, we compared baseline corticosterone (CORT) levels and telomere length in nestlings of the same age. We collected blood samples for hormone assay and telomere determination from two geographically distinct populations of the Thorn-tailed Rayadito (Aphrastura spinicauda) that differed in brood size; nestlings body mass and primary productivity. Within each population we used path analysis to evaluate the relationship between brood size, body mass, baseline CORT and telomere length.
Results: Within each distinct population, path coefficients showed a positive relationship between brood size and baseline CORT and a strong and negative correlation between baseline CORT and telomere length. In general, nestlings that presented higher baseline CORT levels tended to present shorter telomeres. When comparing populations it was the low latitude population that presented higher levels of baseline CORT and shorter telomere length.
Conclusions: Taken together our results reveal the importance of the condition experienced early in life in affecting telomere length, and the relevance of integrative studies carried out in natural conditions.https://frontiersinzoology.biomedcentral.com/articles/10.1186/s12983-016-0133-
Comparison of and Quasielastic Scattering
We formulate -nucleus quasielastic scattering in a manner which closely
parallels standard treatments of -nucleus quasielastic scattering. For
scattering, new responses involving scalar contributions appear in
addition to the Coulomb (or longitudinal) and transverse responses
which are of vector character. We compute these responses using both nuclear
matter and finite nucleus versions of the Relativistic Hartree Approximation to
Quantum Hadrodynamics including RPA correlations. Overall agreement with
measured responses and new quasielastic scattering data for
Ca at |\qs|=500 MeV/c is good. Strong RPA quenching is essential for
agreement with the Coulomb response. This quenching is notably less for the
cross section even though the new scalar contributions are even more
strongly quenched than the vector contributions. We show that this
``differential quenching'' alters sensitive cancellations in the expression for
the cross section so that it is reduced much less than the individual
responses. We emphasize the role of the purely relativistic distinction between
vector and scalar contributions in obtaining an accurate and consistent
description of the and data within the framework of our nuclear
structure model.Comment: 26 pages, 5 uuencoded figures appended to end of this fil
Gamma-ray Observations Under Bright Moonlight with VERITAS
Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive
photomultiplier tube (PMT) cameras. Exposure to high levels of background
illumination degrades the efficiency of and potentially destroys these
photo-detectors over time, so IACTs cannot be operated in the same
configuration in the presence of bright moonlight as under dark skies. Since
September 2012, observations have been carried out with the VERITAS IACTs under
bright moonlight (defined as about three times the night-sky-background (NSB)
of a dark extragalactic field, typically occurring when Moon illumination >
35%) in two observing modes, firstly by reducing the voltage applied to the
PMTs and, secondly, with the addition of ultra-violet (UV) bandpass filters to
the cameras. This has allowed observations at up to about 30 times previous NSB
levels (around 80% Moon illumination), resulting in 30% more observing time
between the two modes over the course of a year. These additional observations
have already allowed for the detection of a flare from the 1ES 1727+502 and for
an observing program targeting a measurement of the cosmic-ray positron
fraction. We provide details of these new observing modes and their performance
relative to the standard VERITAS observations
Faster Correlation Attack on Bluetooth Keystream Generator E0
Abstract. We study both distinguishing and key-recovery attacks against E0, the keystream generator used in Bluetooth by means of correlation. First, a powerful computation method of correlations is formulated by a recursive expression, which makes it easier to calculate correlations of the finite state machine output sequences up to 26 bits for E0 and allows us to verify the two known correlations to be the largest for the first time. Second, we apply the concept of convolution to the analysis of the distinguisher based on all correlations, and propose an efficient distinguisher due to the linear dependency of the largest correlations. Last, we propose a novel maximum likelihood decoding algorithm based on fast Walsh transform to recover the closest codeword for any linear code of dimension L and length n. It requires time O(n + L · 2 L) and memory min(n, 2 L). This can speed up many attacks such as fast correlation attacks. We apply it to E0, and our best key-recovery attack works in 2 39 time given 2 39 consecutive bits after O(2 37) precomputation. This is the best known attack against E0 so far.
Lepton Dipole Moments and Rare Decays in the CP-violating MSSM with Nonuniversal Soft-Supersymmetry Breaking
We investigate the muon anomalous magnetic dipole moment (MDM), the muon
electric dipole moment (EDM) and the lepton-flavour-violating decays of the
lepton, and , in the CP-violating
Minimal Supersymmetric Standard Model (MSSM) with nonuniversal
soft-supersymmetry breaking. We evaluate numerically the muon EDM and the
branching ratios and , after taking
into account the experimental constraints from the electron EDM and muon MDM.
Upon imposition of the experimental limits on our theoretical predictions for
the aforementioned branching ratios and the muon MDM, we obtain an upper bound
of about on the muon EDM which lies well within the
explorable reach of the proposed experiment at BNL.Comment: Latex, 26 pages, 8 figures, accepted for publication in Phys. Rev.
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Prospects for Studies of Stellar Evolution and Stellar Death in the JWST Era
I review the prospects for studies of the advanced evolutionary stages of
low-, intermediate- and high-mass stars by the JWST and concurrent facilities,
with particular emphasis on how they may help elucidate the dominant
contributors to the interstellar dust component of galaxies. Observations
extending from the mid-infrared to the submillimeter can help quantify the
heavy element and dust species inputs to galaxies from AGB stars. JWST's MIRI
mid-infrared instrument will be so sensitive that observations of the dust
emission from individual intergalactic AGB stars and planetary nebulae in the
Virgo Cluster will be feasible. The Herschel Space Observatory will enable the
last largely unexplored spectral region, the far-IR to the submillimeter, to be
surveyed for new lines and dust features, while SOFIA will cover the wavelength
gap between JWST and Herschel, a spectral region containing important fine
structure lines, together with key water-ice and crystalline silicate bands.
Spitzer has significantly increased the number of Type II supernovae that have
been surveyed for early-epoch dust formation but reliable quantification of the
dust contributions from massive star supernovae of Type II, Type Ib and Type Ic
to low- and high-redshift galaxies should come from JWST MIRI observations,
which will be able to probe a volume over 1000 times larger than Spitzer.Comment: 24 pages, 19 figures. To appear in `Astrophysics in the Next Decade:
JWST and Concurrent Facilities' (JWST Conference Proceedings), edited by H.
A. Thronson, M. Stiavelli and A. G. G. M. Tielens; Springer Series:
Astrophysics and Space Science Proceeding
Nonlinear Spin Dynamics in Nuclear Magnets
A method is developed for solving nonlinear systems of differential, or
integrodifferential, equations with stochastic fields. The method makes it
possible to give an accurate solution for an interesting physical problem: What
are the peculiarities of nonlinear spin dynamics in nonequilibrium nuclear
magnets coupled with a resonator? Evolution equations for nuclear spins are
derived basing on a Hamiltonian with dipole interactions. The ensemble of spins
is coupled with a resonator electric circuit. Seven types of main relaxation
regimes are found: free induction, collective induction, free relaxation,
collective relaxation, weak superradiance, pure superradiance, and triggered
superradiance. The initial motion of spins can be originated by two reasons,
either by an imposed initial coherence or by local spin fluctuations due to
nonsecular dipole interactions. The relaxation regimes caused by the second
reason cannot be described by the Bloch equations. Numerical estimates show
good agreement with experiment.Comment: 1 file, 47 pages, LaTe
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