434 research outputs found
Experimental demonstration of higher-order Laguerre-Gauss mode interferometry
The compatibility of higher-order Laguerre-Gauss (LG) modes with
interferometric technologies commonly used in gravitational wave detectors is
investigated. In this paper we present the first experimental results
concerning the performance of the LG33 mode in optical resonators. We show that
the Pound-Drever-Hall error signal for a LG33 mode in a linear optical
resonator is identical to that of the more commonly used LG00 mode, and
demonstrate the feedback control of the resonator with a LG33 mode. We
succeeded to increase the mode purity of a LG33 mode generated using a
spatial-light modulator from 51% to 99% upon transmission through a linear
optical resonator. We further report the experimental verification that a
triangular optical resonator does not transmit helical LG modes
A census of cool core galaxy clusters in IllustrisTNG
The thermodynamic structure of hot gas in galaxy clusters is sensitive to
astrophysical processes and typically difficult to model with galaxy formation
simulations. We explore the fraction of cool-core (CC) clusters in a large
sample of clusters from IllustrisTNG, examining six common CC
definitions. IllustrisTNG produces continuous CC criteria distributions, the
extremes of which are classified as CC and non-cool-core (NCC), and the
criteria are increasingly correlated for more massive clusters. At , the
CC fractions for criteria are in reasonable agreement with the observed
fractions but the other CC fractions are lower than observed. This result
is partly driven by systematic differences between the simulated and observed
gas fraction profiles. The simulated CC fractions with redshift show tentative
agreement with the observed fractions, but linear fits demonstrate that the
simulated evolution is steeper than observed. The conversion of CCs to NCCs
appears to begin later and act more rapidly in the simulations. Examining the
fraction of CCs and NCCs defined as relaxed we find no evidence that CCs are
more relaxed, suggesting that mergers are not solely responsible for disrupting
CCs. A comparison of the median thermodynamic profiles defined by different CC
criteria shows that the extent to which they evolve in the cluster core is
dependent on the CC criteria. We conclude that the thermodynamic structure of
galaxy clusters in IllustrisTNG shares many similarities with observations, but
achieving better agreement most likely requires modifications of the underlying
galaxy formation model.Comment: 24 pages, 17 figures, MNRAS published version. The IllustrisTNG
project website can be found at http://www.tng-project.org
Acclimatory responses of the Daphnia pulex proteome to environmental changes. II. Chronic exposure to different temperatures (10 and 20°C) mainly affects protein metabolism
<p>Abstract</p> <p>Background</p> <p>Temperature affects essentially every aspect of the biology of poikilothermic animals including the energy and mass budgets, activity, growth, and reproduction. While thermal effects in ecologically important groups such as daphnids have been intensively studied at the ecosystem level and at least partly at the organismic level, much less is known about the molecular mechanisms underlying the acclimation to different temperatures. By using 2D gel electrophoresis and mass spectrometry, the present study identified the major elements of the temperature-induced subset of the proteome from differently acclimated <it>Daphnia pulex</it>.</p> <p>Results</p> <p>Specific sets of proteins were found to be differentially expressed in 10°C or 20°C acclimated <it>D. pulex</it>. Most cold-repressed proteins comprised secretory enzymes which are involved in protein digestion (trypsins, chymotrypsins, astacin, carboxypeptidases). The cold-induced sets of proteins included several vitellogenin and actin isoforms (cytoplasmic and muscle-specific), and an AAA+ ATPase. Carbohydrate-modifying enzymes were constitutively expressed or down-regulated in the cold.</p> <p>Conclusion</p> <p>Specific sets of cold-repressed and cold-induced proteins in <it>D. pulex </it>can be related to changes in the cellular demand for amino acids or to the compensatory control of physiological processes. The increase of proteolytic enzyme concentration and the decrease of vitellogenin, actin and total protein concentration between 10°C and 20°C acclimated animals reflect the increased amino-acids demand and the reduced protein reserves in the animal's body. Conversely, the increase of actin concentration in cold-acclimated animals may contribute to a compensatory mechanism which ensures the relative constancy of muscular performance. The sheer number of peptidase genes (serine-peptidase-like: > 200, astacin-like: 36, carboxypeptidase-like: 30) in the <it>D. pulex </it>genome suggests large-scaled gene family expansions that might reflect specific adaptations to the lifestyle of a planktonic filter feeder in a highly variable aquatic environment.</p
Разработка мероприятий по повышению эффективности применяемой системы оплаты труда работников ООО "СЦС"
Gas-phase metallicity gradients of TNG50 star-forming galaxies
We present the radial gas-phase, mass-weighted metallicity profiles and
gradients of the TNG50 star-forming galaxy population measured at redshifts
0--3. We investigate the redshift evolution of gradients and examine
relations between gradient steepness and galaxy properties. We find that TNG50
gradients are predominantly negative at all redshifts, although we observe
significant diversity among these negative gradients. We determine that the
gradient steepness of all galaxies increases approximately monotonically with
redshift at a roughly constant rate. This rate does not vary significantly with
galaxy mass. We observe a weak negative correlation between gradient steepness
and galaxy stellar mass at redshifts . However, when we normalize
gradients by a characteristic radius defined by the galactic star formation
distribution, we find that these normalized gradients remain invariant with
both stellar mass and redshift. We place our results in the context of previous
simulations and show that TNG50 high-redshift gradients are steeper than those
of models featuring burstier feedback, which may further highlight
high-redshift gradients as important discriminators of galaxy formation models.
We also find that redshift and TNG50 gradients are consistent
with the gradients observed in galaxies at these redshifts, although the
preference for flat gradients observed in redshift galaxies is not
present in TNG50. If future JWST and ELT observations validate these flat
gradients, it may indicate a need for simulation models to implement more
powerful radial gas mixing within the ISM, possibly via turbulence and/or
stronger windsComment: 24 pages, 14 figures, submitted to MNRA
Enhancing AGN efficiency and cool-core formation with anisotropic thermal conduction
Understanding how baryonic processes shape the intracluster medium (ICM) is
of critical importance to the next generation of galaxy cluster surveys.
However, most models of structure formation neglect potentially important
physical processes, like anisotropic thermal conduction (ATC). In this letter,
we explore the impact of ATC on the prevalence of cool-cores (CCs) using 12
pairs of magnetohydrodynamical galaxy cluster simulations, simulated using the
IllustrisTNG model with and without ATC. Although the impact of ATC varies from
cluster to cluster and with CC criterion, its inclusion produces a systematic
shift to larger CC fractions at z = 0 for all CC criteria considered.
Additionally, the inclusion of ATC yields a flatter CC fraction redshift
evolution, easing the tension with the observed evolution. With ATC included,
the energy required for the central black hole to achieve self-regulation is
reduced and the gas fraction in the cluster core increases, resulting in larger
CC fractions. ATC makes the ICM unstable to perturbations and the increased
efficiency of AGN feedback suggests that its inclusion results in a greater
level of mixing in the ICM. Therefore, ATC is potentially an important physical
process in reproducing the thermal structure of the ICM.Comment: 5 pages, 4 figures, submitted to MNRAS, comments welcom
Analysis of IL2/IL21 Gene Variants in Cholestatic Liver Diseases Reveals an Association with Primary Sclerosing Cholangitis
Background/Aims: The chromosome 4q27 region harboring IL2 and IL21 is an established risk locus for ulcerative colitis (UC) and various other autoimmune diseases. Considering the strong coincidence of primary sclerosing cholangitis (PSC) with UC and the increased frequency of other autoimmune disorders in patients with primary biliary cirrhosis (PBC), we investigated whether genetic variation in the IL2/IL21 region may also modulate the susceptibility to these two rare cholestatic liver diseases. Methods: Four strongly UC-associated single nucleotide polymorphisms (SNPs) within the KIAA1109/TENR/IL2/IL21 linkage disequilibrium block were genotyped in 124 PBC and 41 PSC patients. Control allele frequencies from 1,487 healthy, unrelated Caucasians were available from a previous UC association study. Results: The minor alleles of all four markers were associated with a decreased susceptibility to PSC (rs13151961: p = 0.013, odds ratio (OR) 0.34; rs13119723: p = 0.023, OR 0.40; rs6822844: p = 0.031, OR 0.41; rs6840978: p = 0.043, OR 0.46). Moreover, a haplotype consisting of the four minor alleles also had a protective effect on PSC susceptibility (p = 0.0084, OR 0.28). A haplotype of the four major alleles was independently associated with PSC when excluding the patients with concomitant inflammatory bowel disease (p = 0.033, OR 4.18). Conclusion: The IL2/IL21 region may be one of the highly suggestive but so far rarely identified shared susceptibility loci for PSC and UC. Copyright (C) 2011 S. Karger AG, Base
Searching for non-Gaussianity in the VSA data
We have tested Very Small Array (VSA) observations of three regions of sky
for the presence of non-Gaussianity, using high-order cumulants, Minkowski
functionals, a wavelet-based test and a Bayesian joint power
spectrum/non-Gaussianity analysis. We find the data from two regions to be
consistent with Gaussianity. In the third region, we obtain a 96.7% detection
of non-Gaussianity using the wavelet test. We perform simulations to
characterise the tests, and conclude that this is consistent with expected
residual point source contamination. There is therefore no evidence that this
detection is of cosmological origin. Our simulations show that the tests would
be sensitive to any residual point sources above the data's source subtraction
level of 20 mJy. The tests are also sensitive to cosmic string networks at an
rms fluctuation level of (i.e. equivalent to the best-fit observed
value). They are not sensitive to string-induced fluctuations if an equal rms
of Gaussian CDM fluctuations is added, thereby reducing the fluctuations due to
the strings network to rms . We especially highlight the usefulness
of non-Gaussianity testing in eliminating systematic effects from our data.Comment: Minor corrections; accepted for publication to MNRA
Estimating the bispectrum of the Very Small Array data
We estimate the bispectrum of the Very Small Array data from the compact and
extended configuration observations released in December 2002, and compare our
results to those obtained from Gaussian simulations. There is a slight excess
of large bispectrum values for two individual fields, but this does not appear
when the fields are combined. Given our expected level of residual point
sources, we do not expect these to be the source of the discrepancy. Using the
compact configuration data, we put an upper limit of 5400 on the value of f_NL,
the non-linear coupling parameter, at 95 per cent confidence. We test our
bispectrum estimator using non-Gaussian simulations with a known bispectrum,
and recover the input values.Comment: 17 pages, 16 figures, replaced with version accepted by MNRAS.
Primordial bispectrum recalculated and figure 11 change
CMB observations from the CBI and VSA: A comparison of coincident maps and parameter estimation methods
We present coincident observations of the Cosmic Microwave Background (CMB)
from the Very Small Array (VSA) and Cosmic Background Imager (CBI) telescopes.
The consistency of the full datasets is tested in the map plane and the Fourier
plane, prior to the usual compression of CMB data into flat bandpowers. Of the
three mosaics observed by each group, two are found to be in excellent
agreement. In the third mosaic, there is a 2 sigma discrepancy between the
correlation of the data and the level expected from Monte Carlo simulations.
This is shown to be consistent with increased phase calibration errors on VSA
data during summer observations. We also consider the parameter estimation
method of each group. The key difference is the use of the variance window
function in place of the bandpower window function, an approximation used by
the VSA group. A re-evaluation of the VSA parameter estimates, using bandpower
windows, shows that the two methods yield consistent results.Comment: 10 pages, 6 figures. Final version. Accepted for publication in MNRA
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