224 research outputs found
Can residuals of the Solar system foreground explain low multipole anomalies of the CMB ?
The low multipole anomalies of the Cosmic Microwave Background has received
much attention during the last few years. It is still not ascertained whether
these anomalies are indeed primordial or the result of systematics or
foregrounds. An example of a foreground, which could generate some non-Gaussian
and statistically anisotropic features at low multipole range, is the very
symmetric Kuiper Belt in the outer solar system. In this paper, expanding upon
the methods presented by Maris et al. (2011), we investigate the contributions
from the Kuiper Belt objects (KBO) to the WMAP ILC 7 map, whereby we can
minimize the contrast in power between even and odd multipoles in the CMB,
discussed discussed by Kim & Naselsky (2010). We submit our KBO de-correlated
CMB signal to several tests, to analyze its validity, and find that
incorporation of the KBO emission can decrease the quadrupole-octupole
alignment and parity asymmetry problems, provided that the KBO signals has a
non-cosmological dipole modulation, associated with the statistical anisotropy
of the ILC 7 map. Additionally, we show that the amplitude of the dipole
modulation, within a 2 sigma interval, is in agreement with the corresponding
amplitudes, discussed by Lew (2008).Comment: 24 pages, 9 figures, 5 tables. Matches version in JCA
The mass-to-light ratio of rich star clusters
We point out a strong time-evolution of the mass-to-light conversion factor
eta commonly used to estimate masses of unresolved star clusters from observed
cluster spectro-photometric measures. We present a series of gas-dynamical
models coupled with the Cambridge stellar evolution tracks to compute
line-of-sight velocity dispersions and half-light radii weighted by the
luminosity. We explore a range of initial conditions, varying in turn the
cluster mass and/or density, and the stellar population's IMF. We find that
eta, and hence the estimated cluster mass, may increase by factors as large as
3 over time-scales of 50 million years. We apply these results to an hypothetic
cluster mass distribution function (d.f.) and show that the d.f. shape may be
strongly affected at the low-mass end by this effect. Fitting truncated
isothermal (Michie-King) models to the projected light profile leads to
over-estimates of the concentration parameter c of delta c ~ 0.3 compared to
the same functional fit applied to the projected mass density.Comment: 6 pages, 2 figures, to appear in the proceedings of the "Young
massive star clusters", Granada, Spain, September 200
On primordial trispectrum from exchanging scalar modes in general multiple field inflationary models
We make an complementary investigation of the primordial trispectrum from
exchanging intermediate scalar modes in multi-field inflation models with
generalized kinetic terms. Together with the calculation of irreducible
contributions to the primordial trispectrum in Ref.[103], we give the full
leading-order primordial trispectrum in generalized multi-field models.Comment: 15 pages, 1 figure; v2 references adde
BINGO: A code for the efficient computation of the scalar bi-spectrum
We present a new and accurate Fortran code, the BI-spectra and
Non-Gaussianity Operator (BINGO), for the efficient numerical computation of
the scalar bi-spectrum and the non-Gaussianity parameter f_{NL} in single field
inflationary models involving the canonical scalar field. The code can
calculate all the different contributions to the bi-spectrum and the parameter
f_{NL} for an arbitrary triangular configuration of the wavevectors. Focusing
firstly on the equilateral limit, we illustrate the accuracy of BINGO by
comparing the results from the code with the spectral dependence of the
bi-spectrum expected in power law inflation. Then, considering an arbitrary
triangular configuration, we contrast the numerical results with the analytical
expression available in the slow roll limit, for, say, the case of the
conventional quadratic potential. Considering a non-trivial scenario involving
deviations from slow roll, we compare the results from the code with the
analytical results that have recently been obtained in the case of the
Starobinsky model in the equilateral limit. As an immediate application, we
utilize BINGO to examine of the power of the non-Gaussianity parameter f_{NL}
to discriminate between various inflationary models that admit departures from
slow roll and lead to similar features in the scalar power spectrum. We close
with a summary and discussion on the implications of the results we obtain.Comment: v1: 5 pages, 5 figures; v2: 35 pages, 11 figures, title changed,
extensively revised; v3: 36 pages, 11 figures, to appear in JCAP. The BINGO
code is available online at
http://www.physics.iitm.ac.in/~sriram/bingo/bingo.htm
Large slow-roll corrections to the bispectrum of noncanonical inflation
Nongaussian statistics are a powerful discriminant between inflationary
models, particularly those with noncanonical kinetic terms. Focusing on
theories where the Lagrangian is an arbitrary Lorentz-invariant function of a
scalar field and its first derivatives, we review and extend the calculation of
the observable three-point function. We compute the "next-order" slow-roll
corrections to the bispectrum in closed form, and obtain quantitative estimates
of their magnitude in DBI and power-law k-inflation. In the DBI case our
results enable us to estimate corrections from the shape of the potential and
the warp factor: these can be of order several tens of percent. We track the
possible sources of large logarithms which can spoil ordinary perturbation
theory, and use them to obtain a general formula for the scale dependence of
the bispectrum. Our result satisfies the next-order version of Maldacena's
consistency condition and an equivalent consistency condition for the scale
dependence. We identify a new bispectrum shape available at next-order, which
is similar to a shape encountered in Galileon models. If fNL is sufficiently
large this shape may be independently detectable.Comment: v1: 37 pages, plus tables, figures and appendices. v2: supersedes
version published in JCAP; some clarifications and more detailed comparison
with earlier literature. All results unchanged. v3:improvements to some
plots; text unchange
Professional closure by proxy: the impact of changing educational requirements on class mobility for a cohort of Big 8 partners
Closure events impacting on class mobility may include mechanisms initiated by bodies other than the professional body. The research examines if the introduction of full-time study requirements at universities for aspiring accountants effectively introduced a closure mechanism in the accounting profession. Data was derived from an Oral History study of partners in large firms. The younger partners (born after the Second World War) completed full-time degree study at university, but did not provide evidence of class mobility into the profession. The older cohort, born between 1928 and 1946, completed part-time studies only, few completed a degree, and, in contrast to the younger cohort, shows a perceptible upward movement from lower socio-economic classes into the professional class. This suggests that changing the preferred educational routes for new accountants entering the large chartered accounting (CA) firms compromised the "stepping stone" function of accounting as a portal into the professional class
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Global maps of soil temperature.
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
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