296 research outputs found
Error analysis in cross-correlation of sky maps: application to the ISW detection
Constraining cosmological parameters from measurements of the Integrated
Sachs-Wolfe effect requires developing robust and accurate methods for
computing statistical errors in the cross-correlation between maps. This paper
presents a detailed comparison of such error estimation applied to the case of
cross-correlation of Cosmic Microwave Background (CMB) and large-scale
structure data. We compare theoretical models for error estimation with
montecarlo simulations where both the galaxy and the CMB maps vary around a
fiducial auto-correlation and cross-correlation model which agrees well with
the current concordance LCDM cosmology. Our analysis compares estimators both
in harmonic and configuration (or real) space, quantifies the accuracy of the
error analysis and discuss the impact of partial sky survey area and the choice
of input fiducial model on dark-energy constraints. We show that purely
analytic approaches yield accurate errors even in surveys that cover only 10%
of the sky and that parameter constraints strongly depend on the fiducial model
employed. Alternatively, we discuss the advantages and limitations of error
estimators that can be directly applied to data. In particular, we show that
errors and covariances from the Jack-Knife method agree well with the
theoretical approaches and simulations. We also introduce a novel method in
real space that is computationally efficient and can be applied to real data
and realistic survey geometries. Finally, we present a number of new findings
and prescriptions that can be useful for analysis of real data and forecasts,
and present a critical summary of the analyses done to date.Comment: submitted to MNRAS, 26 page
Response to Interferon-Beta Treatment in Afro-Caribbeans with Multiple Sclerosis
Background. Multiple sclerosis (MS) patients of African ancestry have a more aggressive disease course than white patients and could be resistant to interferon-beta (INFB). Methods. We studied the impact of INFB in treatment-naive Afro-Caribbean (AC) with clinically definite MS using our European Database for Multiple Sclerosis (EDMUS) (2003–2010). Main outcome measures were annual relapse rate after 2 years of treatment, proportion of exacerbation-free subjects 48 weeks after initiating INFB, and time to first relapse. Results. 76 AC-MS (59F/17M) were identified. Annual relapse rate of 1.29 decreased to 0.83 (−35.6%) after 2 years of treatment. The proportion of relapse-free patients at 48 weeks was 46.2%. Median time to first relapse was 52 weeks. Conclusion. INFB is not strong enough to control AC-MS patients in many cases which is problematic in a population of worse MS prognosis
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Downstream Perforations for the Reduction of Turbulence-Aerofoil Interaction Noise: Part II-Theoretical Investigation
The imprints of primordial non-gaussianities on large-scale structure: scale dependent bias and abundance of virialized objects
We study the effect of primordial nongaussianity on large-scale structure,
focusing upon the most massive virialized objects. Using analytic arguments and
N-body simulations, we calculate the mass function and clustering of dark
matter halos across a range of redshifts and levels of nongaussianity. We
propose a simple fitting function for the mass function valid across the entire
range of our simulations. We find pronounced effects of nongaussianity on the
clustering of dark matter halos, leading to strongly scale-dependent bias. This
suggests that the large-scale clustering of rare objects may provide a
sensitive probe of primordial nongaussianity. We very roughly estimate that
upcoming surveys can constrain nongaussianity at the level |fNL| <~ 10,
competitive with forecasted constraints from the microwave background.Comment: 16 pages, color figures, revtex4. v2: added references and an
equation. submitted to PRD. v3: simplified derivation, additional reference
Cross-correlation of WMAP 3rd year and the SDSS DR4 galaxy survey: new evidence for Dark Energy
We cross-correlate the third-year WMAP data with galaxy samples extracted
from the SDSS DR4 (SDSS4) covering 13% of the sky, increasing by a factor of
3.7 the volume sampled in previous analyses. The new measurements confirm a
positive cross-correlation with higher significance (total signal-to-noise of
about 4.7). The correlation as a function of angular scale is well fitted by
the integrated Sachs-Wolfe (ISW) effect for LCDM flat FRW models with a
cosmological constant. The combined analysis of different samples gives
Omega_L=0.80-0.850.77-0.86$ (95% CL). We find
similar best fit values for Omega_L for different galaxy samples with median
redshifts of z ~0.3 and z ~0.5, indicating that the data scale with redshift as
predicted by the LCDM cosmology (with equation of state parameter w=-1). This
agreement is not trivial, but can not yet be used to break the degeneracy
constraints in the w versus Omega_L plane using only the ISW data.Comment: 5 pages, final version to be published by MNRAS Let. Minor changes
with some additional clarification on error analysis don
Assessing the impact of an offshore longline mussel farm on local water circulation in a highly hydrodynamic energetic bay
Downstream porosity for the reduction of turbulence-aerofoil interaction noise
Data availability: Data will be made available on request.Copyright © 2022 The Author(s). This paper is a predominantly experimental study into the use of porosity located downstream of an aerofoil leading edge for the reduction of turbulence interaction noise. Locating the porosity downstream of the leading edge has been shown to be beneficial in reducing the aerodynamic performance penalty compared with locating it directly at the leading edge [1], where most of the lift is generated. Noise measurements on a flat plate with downstream porosity are compared against the case of two flat plates in a tandem configuration. In
both cases, the noise reduction spectra exhibit peaks of strong noise reduction at non-dimensional frequencies of fld/Uc = n, where ld is the distance between the leading edge and the downstream edge, Uc is the convection velocity and n is an integer. To explain this behaviour requires a mechanism to be present
in which a phase shift of 180◦ is introduced in the interaction process. In the paper we argue that the origin of this phase shift is due to secondary vorticity generated at the leading edge. Another key finding of this paper is that overall noise reductions are due to an effective shortening of the chord in which most of the radiation is produced by the section of the flat plate upstream of the porous section, leading to generally weaker radiation. Neither of these mechanisms have been reported previously in the literature. The paper concludes with noise
measurements on a thin aerofoil with downstream porosity included, in which overall noise reductions of up to 2.8 dB are achieved.EPSRC (EP/V00686X/1) QUADPORS project; Royal Academy of Engineering (RF\201819 \ 18 \ 194); EPSRC DTP EP/N509620/1; Christ’s College, University of Cambridge; EPSRC Early Career Fellowship EP/P015980/1; Oscar Propulsion; Rolls-Royce
Meropenem vs standard of care for treatment of neonatal late onset sepsis (NeoMero1): A randomised controlled trial.
BACKGROUND: The early use of broad-spectrum antibiotics remains the cornerstone for the treatment of neonatal late onset sepsis (LOS). However, which antibiotics should be used is still debatable, as relevant studies were conducted more than 20 years ago, recruited in single centres or countries, evaluated antibiotics not in clinical use anymore and had variable inclusion/exclusion criteria and outcome measures. Moreover, antibiotic-resistant bacteria have become a major problem in many countries worldwide. We hypothesized that efficacy of meropenem as a broad-spectrum antibiotic is superior to standard of care regimens (SOC) in empiric treatment of LOS and aimed to compare meropenem to SOC in infants aged 44 weeks meeting the Goldstein criteria of sepsis, were randomized in a 1:1 ratio to receive meropenem or one of the two SOC regimens (ampicillin+gentamicin or cefotaxime+gentamicin) chosen by each site prior to the start of the study for 8-14 days. The primary outcome was treatment success (survival, no modification of allocated therapy, resolution/improvement of clinical and laboratory markers, no need of additional antibiotics and presumed/confirmed eradication of pathogens) at test-of-cure visit (TOC) in full analysis set. Stool samples were tested at baseline and Day 28 for meropenem-resistant Gram-negative organisms (CRGNO). The primary analysis was performed in all randomised patients and in patients with culture confirmed LOS. Proportions of participants with successful outcome were compared by using a logistic regression model adjusted for the stratification factors. From September 3, 2012 to November 30th 2014, total of 136 patients (instead of planned 275) in each arm were randomized; 140 (52%) were culture positive. Successful outcome at TOC was achieved in 44/136 (32%) in the meropenem arm vs. 31/135 (23%) in the SOC arm (p = 0.087). The respective numbers in patients with positive cultures were 17/63 (27%) vs. 10/77 (13%) (p = 0.022). The main reason of failure was modification of allocated therapy. Treatment emergent adverse events occurred in 72% and serious adverse events in 17% of patients, the Day 28 mortality was 6%. Cumulative acquisition of CRGNO by Day 28 occurred in 4% of patients in the meropenem and 12% in the SOC arm (p = 0.052). CONCLUSIONS: Within this study population, we found no evidence that meropenem was superior to SOC in terms of success at TOC, short term hearing disturbances, safety or mortality were similar in both treatment arms but the study was underpowered to detect the planned effect. Meropenem treatment did not select for colonization with CRGNOs. We suggest that meropenem as broad-spectrum antibiotic should be reserved for neonates who are more likely to have Gram-negative LOS, especially in NICUs where microorganisms producing extended spectrum- and AmpC type beta-lactamases are circulating
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