683 research outputs found
An indirect limit on the amplitude of primordial Gravitational Wave Background from CMB-Galaxy Cross Correlation
While large scale cosmic microwave background (CMB) anisotropies involve a
combination of the scalar and tensor fluctuations, the scalar amplitude can be
independently determined through the CMB-galaxy cross-correlation. Using
recently measured cross-correlation amplitudes, arising from the
cross-correlation between galaxies and the Integrated Sachs Wolfe effect in CMB
anisotropies, we obtain a constraint r < 0.5 at 68% confidence level on the
tensor-to-scalar fluctuation amplitude ratio. The data also allow us to exclude
gravity waves at a level of a few percent, relative to the density field, in a
low - Lambda dominated universe(Omega_Lambda~0.5). In future, joining
cross-correlation ISW measurements, which captures cosmological parameter
information, with independent determinations of the matter density and CMB
anisotropy power spectrum, may constrain the tensor-to-scalar ratio to a level
above 0.05. This value is the ultimate limit on tensor-to-scalar ratio from
temperature anisotropy maps when all other cosmological parameters except for
the tensor amplitude are known and the combination with CMB-galaxy correlation
allows this limit to be reached easily by accounting for degeneracies in
certain cosmological parameters.Comment: 5 Pages, 1 Figure, revised discussion on cosmic variance limits on
the tensor-to-scalar ratio from CMB, matches PRD accepted versio
Constraining dark sector perturbations II: ISW and CMB lensing tomography
Any Dark Energy (DE) or Modified Gravity (MG) model that deviates from a
cosmological constant requires a consistent treatment of its perturbations,
which can be described in terms of an effective entropy perturbation and an
anisotropic stress. We have considered a recently proposed generic
parameterisation of DE/MG perturbations and compared it to data from the Planck
satellite and six galaxy catalogues, including temperature-galaxy (Tg), CMB
lensing-galaxy and galaxy-galaxy (gg) correlations. Combining these observables
of structure formation with tests of the background expansion allows us to
investigate the properties of DE/MG both at the background and the perturbative
level. Our constraints on DE/MG are mostly in agreement with the cosmological
constant paradigm, while we also find that the constraint on the equation of
state w (assumed to be constant) depends on the model assumed for the
perturbation evolution. We obtain (95% CL; CMB+gg+Tg)
in the entropy perturbation scenario; in the anisotropic stress case the result
is . Including the lensing correlations shifts the
results towards higher values of w. If we include a prior on the expansion
history from recent Baryon Acoustic Oscillations (BAO) measurements, we find
that the constraints tighten closely around , making it impossible to
measure any DE/MG perturbation evolution parameters. If, however, upcoming
observations from surveys like DES, Euclid or LSST show indications for a
deviation from a cosmological constant, our formalism will be a useful tool
towards model selection in the dark sector.Comment: 25 pages, 8 figures; minor update for consistency with version
accepted by JCAP (13/01/2015
Improved survival with initial MRSA therapy in high-risk community-onset pneumonia patients : application of a MRSA risk score
textCommunity-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is an evolving problem, and there is a great need for a reliable method to assess MRSA risk at hospital admission. A new MRSA prediction score classifies CO-pneumonia patients into low, medium, and high-risk groups based on objective criteria available at baseline. Our objective was to assess the effect of initial MRSA therapy on mortality in these three risk groups. We conducted a retrospective cohort study using data from the Veterans Health Administration. Patients were included if they were hospitalized with pneumonia and received antibiotics within the first 48 hours of admission. They were stratified into MRSA therapy and no MRSA therapy treatment arms based on antibiotics received in the first 48 hours. MRSA risk groups were analyzed separately. The primary outcome was 30-day patient mortality. Multivariable logistic regression was used to adjust for potential confounders. A total of 80,330 patients met inclusion criteria, of which 36% received MRSA therapy and 64% did not receive MRSA therapy. The majority of patients were classified as either low (51%) or medium (47%) risk, with only 2% classified as high-risk. In the high-risk group, unadjusted 30-day mortality was lower among patients who received initial MRSA therapy (40% versus 58%; p<0.0001). Likewise, multivariable logistic regression analysis also demonstrated that initial MRSA therapy was associated with a lower 30-day mortality in the high-risk group (adjusted odds ratio 0.57; 95% confidence interval 0.42-0.77). There was no benefit of initial MRSA therapy in the low or medium-risk groups. This study demonstrated improved survival with initial MRSA therapy in high-risk CO-pneumonia patients. The MRSA risk score should not replace clinical judgment, but it might be a useful tool to spare MRSA therapy for only those patients who are most likely to benefit.Pharmaceutical Science
Letter. On the activation of [CrCl3{R-SN(H)S-R}] catalysts for selective trimerization of ethene: a freeze-quench Cr K-edge XAFS study
Homogeneous chromium catalysts for the selective conversion of ethene to hex-1-ene are formed from Cr(III) reagents, amino-thioether ligands of the type HN(CH2CH2SR)2, and aluminum reagents. In this study the early activation steps are investigated by EPR, UV-visible and Cr K-edge XAFS spectroscopy; rapid stopped-flow mixing and a freeze-quench allows good quality EXAFS analysis of a species formed in ~ 1 second of reaction. This is shown to involve reduction to Cr(II) and deprotonation of a NH group of the auxiliary ligand. This 4-coordinate metal-center may act as precursor for the coordination of ethene and subsequent selective oligomerization
Frontal brain asymmetries as effective parameters to assess the quality of audiovisual stimuli perception in adult and young cochlear implant users
How is music perceived by cochlear implant (CI) users? This question arises as "the next step" given the impressive performance obtained by these patients in language perception. Furthermore, how can music perception be evaluated beyond self-report rating, in order to obtain measurable data? To address this question, estimation of the frontal electroencephalographic (EEG) alpha activity imbalance, acquired through a 19-channel EEG cap, appears to be a suitable instrument to measure the approach/withdrawal (AW index) reaction to external stimuli. Specifically, a greater value of AW indicates an increased propensity to stimulus approach, and vice versa a lower one a tendency to withdraw from the stimulus. Additionally, due to prelingually and postlingually deafened pathology acquisition, children and adults, respectively, would probably differ in music perception. The aim of the present study was to investigate children and adult CI users, in unilateral (UCI) and bilateral (BCI) implantation conditions, during three experimental situations of music exposure (normal, distorted and mute). Additionally, a study of functional connectivity patterns within cerebral networks was performed to investigate functioning patterns in different experimental populations. As a general result, congruency among patterns between BCI patients and control (CTRL) subjects was seen, characterised by lowest values for the distorted condition (vs. normal and mute conditions) in the AW index and in the connectivity analysis. Additionally, the normal and distorted conditions were significantly different in CI and CTRL adults, and in CTRL children, but not in CI children. These results suggest a higher capacity of discrimination and approach motivation towards normal music in CTRL and BCI subjects, but not for UCI patients. Therefore, for perception of music CTRL and BCI participants appear more similar than UCI subjects, as estimated by measurable and not self-reported parameters
The FDA âblack boxâ warning on antidepressant suicide risk in young adults: More harm than benefits?
The decision made in the year 2004 by the U.S. Food and Drug Administration (FDA) to require a boxed warning on antidepressants regarding the risk of suicidality in young adults still represents a matter of controversy. The FDA warning was grounded on industry-sponsored trials carried one decade ago or earlier. However, within the past decade, an increasing number of reports have questioned the actual validity of the FDA warning, especially considering a decline in the prescription of the antidepressant drugs associated with an increase in the rate of suicidal events among people with severe depression. The present report provides an overview of the FDA black box warning, also documenting two Major Depressive Disorder patients whose refusal to undergo a pharmacological antidepressant treatment possibly led to an increased risk for suicidal behaviors. The concerns raised by the FDA black box warning need to be considered in real-world clinical practice, stating the associated clinical and public health implications
ISW effect in Unified Dark Matter Scalar Field Cosmologies: an analytical approach
We perform an analytical study of the Integrated Sachs-Wolfe (ISW) effect
within the framework of Unified Dark Matter models based on a scalar field
which aim at a unified description of dark energy and dark matter. Computing
the temperature power spectrum of the Cosmic Microwave Background anisotropies
we are able to isolate those contributions that can potentially lead to strong
deviations from the usual ISW effect occurring in a CDM universe. This
helps to highlight the crucial role played by the sound speed in the Unified
Dark Matter models. Our treatment is completely general in that all the results
depend only on the speed of sound of the dark component and thus it can be
applied to a variety of unified models, including those which are not described
by a scalar field but relies on a single dark fluid.Comment: 15 pages, LateX file; one comment after Eq.(36) and formula (44)
added in order to underline procedure and main results. Accepted for
publication in JCAP; some typos correcte
Constraining dark energy with cross-correlated CMB and Large Scale Structure data
We investigate the possibility of constraining dark energy with the
Integrated Sachs Wolfe effect recently detected by cross-correlating the WMAP
maps with several Large Scale Structure surveys. In agreement with previous
works, we found that, under the assumption of a flat universe, the ISW signal
is a promising tool for constraining dark energy. Current available data put
weak limits on a constant dark energy equation of state w. We also find no
constraints on the dark energy sound speed c_e^2. For quintessence-like dark
energy (c_e^2=1) we find w<-0.53, while tighter bounds are possible only if the
dark energy is ``clustered'' (c_e^2=0), in such a case -1.94<w<-0.63 at
2-sigma. Better measurements of the CMB-LSS correlation will be possible with
the next generation of deep redshift surveys. This will provide independent
constraints on the dark energy which are alternative to those usually inferred
from CMB and SN-Ia data.Comment: 7 pages, 7 figures, extended discussion on baryon density and
covariance matrix, matches PRD accepted versio
Structural origins of voltage mysteresis in the Na-Ion cathode P2-Na0.67[Mg0.28Mn0.72]O2 : A combined spectroscopic and density functional theory study
Funding Information: E.N.B. acknowledges funding from the Engineering Physical Sciences Research Council (EPSRC) via the National Productivity Interest Fund (NPIF) 2018 and is also grateful for use of the ARCHER UK National Supercomputing Service via our membership in the UKâs HEC Materials Chemistry Consortium, funded by the EPSRC (EP/L000202). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, through the U.S. Department of Energy, Office of Basic Energy Sciences, Contract DE-AC02-98CH10866. P.J.R. thanks the Northeast Centre for Chemical Energy Storage (NECCES), an Energy Frontier Research Centre funded by the US Department of Energy, Office of Basic Energy Sciences, award DE-SC0012583. M.A.J. is grateful for the financial support of the EPSRC Centre for Doctoral Training (CDT) in Nanoscience and Nanotechnology Award EP/L015978/1. J.L. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2019R1A6A1A10073437). E.N.B. also wishes to thank Dr M.F. Groh for assistance with setting up capillary XRD measurements. Publisher Copyright: ©Peer reviewedPublisher PD
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