316 research outputs found
Triggering and Data Acquisition General Considerations
No abstract prepared
Redshift Evolution in the Iron Abundance of the Intracluster Medium
Clusters of galaxies provide a closed box within which one can determine the
chemical evolution of the gaseous baryons with cosmic time. We studied this
metallicity evolution in the hot X-ray emitting baryons through an analysis of
XMM-Newton observations of 29 galaxy clusters in the redshift range 0.3 < z <
1.3. Taken alone, this data set does not show evidence for significant
evolution. However, when we also include a comparable sample of 115 clusters
observed with Chandra (Maughan et al. 2008) and a lower redshift sample of 70
clusters observed with XMM at z < 0.3 (Snowden et al. 2008), there is
definitive evidence for a decrease in the metallicity. This decrease is
approximately a factor of two from z = 0 to z \approx 1, over which we find a
least-squares best-fit line Z(z) / Z_{\odot} = (0.46 \pm 0.05) - (0.38 \pm
0.03)z. The greatest uncertainty in the evolution comes from poorly constrained
metallicities in the highest redshift bin
Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments
We provide evidence that the obliquities of stars with close-in giant planets
were initially nearly random, and that the low obliquities that are often
observed are a consequence of star-planet tidal interactions. The evidence is
based on 14 new measurements of the Rossiter-McLaughlin effect (for the systems
HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16,
WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, and Kepler-8), as well as a
critical review of previous observations. The low-obliquity (well-aligned)
systems are those for which the expected tidal timescale is short, and likewise
the high-obliquity (misaligned and retrograde) systems are those for which the
expected timescale is long. At face value, this finding indicates that the
origin of hot Jupiters involves dynamical interactions like planet-planet
interactions or the Kozai effect that tilt their orbits, rather than
inspiraling due to interaction with a protoplanetary disk. We discuss the
status of this hypothesis and the observations that are needed for a more
definitive conclusion.Comment: Accepted for publication in ApJ; typos corrected, 2 broken references
fixed, 26 pages, 25 figure
The HAT-P-13 Exoplanetary System: Evidence for Spin-Orbit Alignment and a Third Companion
We present new radial velocity (RV) measurements of HAT-P-13, a star with two previously known companions: a transiting giant planet "b" with an orbital period of 3 days and a more massive object "c" on a 1.2 yr, highly eccentric orbit. For this system, dynamical considerations would lead to constraints on planet b's interior structure, if it could be shown that the orbits are coplanar and apsidally locked. By modeling the Rossiter-McLaughlin effect, we show that planet b's orbital angular momentum vector and the stellar spin vector are well aligned on the sky ([lambda] = 1.9 ± 8.6 deg). The refined orbital solution favors a slightly eccentric orbit for planet b (e = 0.0133 ± 0.0041), although it is not clear whether it is apsidally locked with c's orbit ([DELTA][omega]= 36[superscript +27] [subscript â36]deg). We find a long-term trend in the star's RV and interpret it as evidence for an additional body "d," which may be another planet or a low-mass star. Predictions are given for the next few inferior conjunctions of c, when transits may happen.Massachusetts Institute of Technology (Class of 1942)United States. National Aeronautics and Space Administration (Origins program, award NNX09AD36G)National Science Foundation (U.S.) (Grant No. NSF PHY05-51164)W. M. Keck Foundatio
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.Comment: 49 pages, 16 figures, accepted by A
5-Hydroxytryptamine receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
oai:ojs.pkp.sfu.ca:article/31555-HT receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on 5-HT receptors [194] and subsequently revised [176]) are, with the exception of the ionotropic 5-HT3 class, GPCRs where the endogenous agonist is 5-hydroxytryptamine. The diversity of metabotropic 5-HT receptors is increased by alternative splicing that produces isoforms of the 5-HT2A (non-functional), 5-HT2C (non-functional), 5-HT4, 5-HT6 (non-functional) and 5-HT7 receptors. Unique amongst the GPCRs, RNA editing produces 5-HT2C receptor isoforms that differ in function, such as efficiency and specificity of coupling to Gq/11 and also pharmacology [40, 482]. Most 5-HT receptors (except 5-ht1e and 5-ht5b) play specific roles mediating functional responses in different tissues (reviewed by [463, 382])
5-Hydroxytryptamine receptors in GtoPdb v.2023.1
5-HT receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on 5-HT receptors [198] and subsequently revised [180]) are, with the exception of the ionotropic 5-HT3 class, GPCRs where the endogenous agonist is 5-hydroxytryptamine. The diversity of metabotropic 5-HT receptors is increased by alternative splicing that produces isoforms of the 5-HT2A (non-functional), 5-HT2C (non-functional), 5-HT4, 5-HT6 (non-functional) and 5-HT7 receptors. Unique amongst the GPCRs, RNA editing produces 5-HT2C receptor isoforms that differ in function, such as efficiency and specificity of coupling to Gq/11 and also pharmacology [40, 491]. Most 5-HT receptors (except 5-ht1e and 5-ht5b) play specific roles mediating functional responses in different tissues (reviewed by [471, 387])
The Association of a SNP Upstream of INSIG2 with Body Mass Index is Reproduced in Several but Not All Cohorts
A SNP upstream of the INSIG2 gene, rs7566605, was recently found to be associated with obesity as measured by body mass index (BMI) by Herbert and colleagues. The association between increased BMI and homozygosity for the minor allele was first observed in data from a genome-wide association scan of 86,604 SNPs in 923 related individuals from the Framingham Heart Study offspring cohort. The association was reproduced in four additional cohorts, but was not seen in a fifth cohort. To further assess the general reproducibility of this association, we genotyped rs7566605 in nine large cohorts from eight populations across multiple ethnicities (total n = 16,969). We tested this variant for association with BMI in each sample under a recessive model using family-based, population-based, and case-control designs. We observed a significant (p < 0.05) association in five cohorts but saw no association in three other cohorts. There was variability in the strength of association evidence across examination cycles in longitudinal data from unrelated individuals in the Framingham Heart Study Offspring cohort. A combined analysis revealed significant independent validation of this association in both unrelated (p = 0.046) and family-based (p = 0.004) samples. The estimated risk conferred by this allele is small, and could easily be masked by small sample size, population stratification, or other confounders. These validation studies suggest that the original association is less likely to be spurious, but the failure to observe an association in every data set suggests that the effect of SNP rs7566605 on BMI may be heterogeneous across population samples
THE AGORA HIGH-RESOLUTION GALAXY SIMULATIONS COMPARISON PROJECT. II. ISOLATED DISK TEST
Using an isolated Milky Way-mass galaxy simulation, we compare results from nine state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e.g., radiative cooling and UV background by the standardized package Grackle) and common analysis toolkit yt, all of which are publicly available. Subgrid physics models such as Jeans pressure floor, star formation, supernova feedback energy, and metal production are carefully constrained across code platforms. With numerical accuracy that resolves the disk scale height, we find that the codes overall agree well with one another in many dimensions including: gas and stellar surface densities, rotation curves, velocity dispersions, density and temperature distribution functions, disk vertical heights, stellar clumps, star formation rates, and Kennicutt-Schmidt relations. Quantities such as velocity dispersions are very robust (agreement within a few tens of percent at all radii) while measures like newly formed stellar clump mass functions show more significant variation (difference by up to a factor of âŒ3). Systematic differences exist, for example, between mesh-based and particle-based codes in the low-density region, and between more diffusive and less diffusive schemes in the high-density tail of the density distribution. Yet intrinsic code differences are generally small compared to the variations in numerical implementations of the common subgrid physics such as supernova feedback. Our experiment reassures that, if adequately designed in accordance with our proposed common parameters, results of a modern high-resolution galaxy formation simulation are more sensitive to input physics than to intrinsic differences in numerical schemes
- âŠ