360 research outputs found
Power Spectrum of Velocity Fluctuations in the Universe
We investigate the power spectrum of velocity fluctuations in the universe,
, starting from four different measures of velocity: (1) the power
spectrum of velocity fluctuations from peculiar velocities of galaxies; (2) the
rms peculiar velocity of galaxy clusters; (3) the power spectrum of velocity
fluctuations from the power spectrum of density fluctuations in the galaxy
distribution; (4) and the bulk velocity from peculiar velocities of galaxies.
We show that measures (1) and (2) are not consistent with each other and either
the power spectrum from peculiar velocities of galaxies is overestimated or the
rms cluster peculiar velocity is underestimated. The amplitude of velocity
fluctuations derived from the galaxy distribution (measure 3) depends on the
parameter . We estimate the parameter on the basis of measures
(2) and (4). The power spectrum of velocity fluctuations from the galaxy
distribution in the Stromlo-APM redshift survey is consistent with the observed
rms cluster velocity and with the observed large-scale bulk flow when the
parameter is in the range 0.4-0.5. In this case the value of the
function at wavelength Mpc is km s
and the rms amplitude of the bulk flow at the radius Mpc is km s. The velocity dispersion of galaxy systems originates mostly
from the large-scale velocity fluctuations with wavelengths Mpc.Comment: Astrophysical Journal, Vol. 493, in press: 23 pages, uses AAS Latex,
and 14 separate postscript figure
The 2dF galaxy redshift survey: near-infrared galaxy luminosity functions
We combine the Two Micron All Sky Survey (2MASS) Extended Source Catalogue and the 2dF Galaxy Redshift Survey to produce an infrared selected galaxy catalogue with 17 173 measured redshifts. We use this extensive data set to estimate the galaxy luminosity functions in the J- and KS-bands. The luminosity functions are fairly well fitted by Schechter functions with parameters MJ*−5 log h=−22.36±0.02, αJ=−0.93±0.04, ΦJ*=0.0104±0.0016 h3 Mpc3 in the J-band and MKS*−5 log h=−23.44±0.03, αKS=−0.96±0.05, ΦKS*=0.0108±0.0016 h3 Mpc3 in the KS-band (2MASS Kron magnitudes). These parameters are derived assuming a cosmological model with Ω0=0.3 and Λ0=0.7. With data sets of this size, systematic rather than random errors are the dominant source of uncertainty in the determination of the luminosity function. We carry out a careful investigation of possible systematic effects in our data. The surface brightness distribution of the sample shows no evidence that significant numbers of low surface brightness or compact galaxies are missed by the survey. We estimate the present-day distributions of bJ−KS and J−KS colours as a function of the absolute magnitude and use models of the galaxy stellar populations, constrained by the observed optical and infrared colours, to infer the galaxy stellar mass function. Integrated over all galaxy masses, this yields a total mass fraction in stars (in units of the critical mass density) of Ωstarsh =(1.6±0.24)×103 for a Kennicutt initial mass function (IMF) and Ωstarsh =(2.9±0.43)×103 for a Salpeter IMF. These values are consistent with those inferred from observational estimates of the total star formation history of the Universe provided that dust extinction corrections are modest
Association of Same-Day Discharge After Elective Percutaneous Coronary Intervention in the United States With Costs and Outcomes
Importance
Same-day discharge (SDD) after elective percutaneous coronary intervention (PCI) is associated with lower costs and preferred by patients. However, to our knowledge, contemporary patterns of SDD after elective PCI with respect to the incidence, hospital variation, trends, costs, and safety outcomes in the United States are unknown.
Objective
To examine (1) the incidence and trends in SDD; (2) hospital variation in SDD; (3) the association between SDD and readmissions for bleeding, acute kidney injury (AKI), acute myocardial infarction (AMI), or mortality at 30, 90, and 365 days after PCI; and (4) hospital costs of SDD and its drivers.
Design, Setting, and Participants
This observational cross-sectional cohort study included 672 470 patients enrolled in the nationally representative Premier Healthcare Database who underwent elective PCI from 493 hospitals between January 2006 and December 2015 with 1-year follow-up.
Exposures
Same-day discharge, defined by identical dates of admission, PCI procedure, and discharge.
Main Outcomes and Measures
Death, bleeding requiring a blood transfusion, AKI and AMI at 30, 90, or 365 days after PCI, and costs from hospitals’ perspective, inflated to 2016.
Results
Among 672 470 elective PCIs, 221 997 patients (33.0%) were women, 30 711 (4.6%) were Hispanic, 51 961 (7.7%) were African American, and 491 823 (73.1%) were white. The adjusted rate of SDD was 3.5% (95% CI, 3.0%-4.0%), which increased from 0.4% in 2006 to 6.3% in 2015. We observed substantial hospital variation for SDD from 0% to 83% (median incidence rate ratio, 3.82; 95% CI, 3.48-4.23), implying an average (median) 382% likelihood of SDD at one vs another hospital. Among SDD (vs non-SDD) patients, there was no higher risk of death, bleeding, AKI, or AMI at 30, 90, or 365 days. Same-day discharge was associated with a large cost savings of 5006-129 million in this sample and 5000 per PCI associated with SDD, greater and more consistent use of SDD could markedly increase the overall value of PCI care
Advances in prevention and therapy of neonatal dairy calf diarrhoea : a systematical review with emphasis on colostrum management and fluid therapy
Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota-and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy
The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe
We present a detailed analysis of the two-point correlation function, ξ(σ, π), from the 2dF Galaxy Redshift Survey (2dFGRS). The large size of the catalogue, which contains ∼220 000 redshifts, allows us to make high-precision measurements of various properties of the galaxy clustering pattern. The effective redshift at which our estimates are made is zs≈ 0.15, and similarly the effective luminosity, Ls≈ 1.4L*. We estimate the redshift-space correlation function, ξ(s), from which we measure the redshift-space clustering length, s0= 6.82 ± 0.28 h−1 Mpc. We also estimate the projected correlation function, Ξ(σ), and the real-space correlation function, ξ(r), which can be fit by a power law (r/r0), with r0= 5.05 ± 0.26 h−1 Mpc, γr= 1.67 ± 0.03. For r≳ 20 h−1 Mpc, ξ drops below a power law as, for instance, is expected in the popular Λ cold dark matter model. The ratio of amplitudes of the real- and redshift-space correlation functions on scales of 8–30 h−1 Mpc gives an estimate of the redshift-space distortion parameter β. The quadrupole moment of ξ(σ, π) on scales 30–40 h−1 Mpc provides another estimate of β. We also estimate the distribution function of pairwise peculiar velocities, ƒ(v), including rigorously the significant effect due to the infall velocities, and we find that the distribution is well fit by an exponential form. The accuracy of our ξ(σ, π) measurement is sufficient to constrain a model, which simultaneously fits the shape and amplitude of ξ(r) and the two redshift-space distortion effects parametrized by β and velocity dispersion, a. We find β= 0.49 ± 0.09 and a= 506 ± 52 km s−1, although the best-fitting values are strongly correlated. We measure the variation of the peculiar velocity dispersion with projected separation, a(σ), and find that the shape is consistent with models and simulations. This is the first time that β and ƒ(v) have been estimated from a self-consistent model of galaxy velocities. Using the constraints on bias from recent estimates, and taking account of redshift evolution, we conclude that β (L=L*, z= 0) = 0.47 ± 0.08, and that the present-day matter density of the Universe, Ωm≈ 0.3, consistent with other 2dFGRS estimates and independent analyses
Sporadic fatal insomnia in a young woman: A diagnostic challenge: Case Report
<p>Abstract</p> <p>Background</p> <p>Sporadic fatal insomnia (sFI) and fatal familial insomnia (FFI) are rare human prion diseases.</p> <p>Case Presentation</p> <p>We report a case of a 33-year-old female who died of a prion disease for whom the diagnosis of sFI or FFI was not considered clinically. Following death of this patient, an interview with a close family member indicated the patient's illness included a major change in her sleep pattern, corroborating the reported autopsy diagnosis of sFI. Genetic tests identified no prion protein (PrP) gene mutation, but neuropathological examination and molecular study showed protease-resistant PrP (PrP<sup>res</sup>) in several brain regions and severe atrophy of the anterior-ventral and medial-dorsal thalamic nuclei similar to that described in FFI.</p> <p>Conclusions</p> <p>In patients with suspected prion disease, a characteristic change in sleep pattern can be an important clinical clue for identifying sFI or FFI; polysomnography (PSG), genetic analysis, and nuclear imaging may aid in diagnosis.</p
Large Scale Structure of the Universe
Galaxies are not uniformly distributed in space. On large scales the Universe
displays coherent structure, with galaxies residing in groups and clusters on
scales of ~1-3 Mpc/h, which lie at the intersections of long filaments of
galaxies that are >10 Mpc/h in length. Vast regions of relatively empty space,
known as voids, contain very few galaxies and span the volume in between these
structures. This observed large scale structure depends both on cosmological
parameters and on the formation and evolution of galaxies. Using the two-point
correlation function, one can trace the dependence of large scale structure on
galaxy properties such as luminosity, color, stellar mass, and track its
evolution with redshift. Comparison of the observed galaxy clustering
signatures with dark matter simulations allows one to model and understand the
clustering of galaxies and their formation and evolution within their parent
dark matter halos. Clustering measurements can determine the parent dark matter
halo mass of a given galaxy population, connect observed galaxy populations at
different epochs, and constrain cosmological parameters and galaxy evolution
models. This chapter describes the methods used to measure the two-point
correlation function in both redshift and real space, presents the current
results of how the clustering amplitude depends on various galaxy properties,
and discusses quantitative measurements of the structures of voids and
filaments. The interpretation of these results with current theoretical models
is also presented.Comment: Invited contribution to be published in Vol. 8 of book "Planets,
Stars, and Stellar Systems", Springer, series editor T. D. Oswalt, volume
editor W. C. Keel, v2 includes additional references, updated to match
published versio
Evaluation of a Bioabsorbable Self-Expandable Vein Stent-Base Made of Poly(<sub>L</sub>-lactide) In Vitro and In Vivo
On some spaces of almost lacunary convergent sequences derived by Riesz mean and weighted almost lacunary statistical convergence in a real n-normed space
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