5,633 research outputs found
The LIL for -statistics in Hilbert spaces
We give necessary and sufficient conditions for the (bounded) law of the
iterated logarithm for -statistics in Hilbert spaces. As a tool we also
develop moment and tail estimates for canonical Hilbert-space valued
-statistics of arbitrary order, which are of independent interest
Constraints on dark energy models from radial baryon acoustic scale measurements
We use the radial baryon acoustic oscillation (BAO) measurements of Gaztanaga
et al. (2008) to constrain parameters of dark energy models. These constraints
are comparable with constraints from other "non-radial" BAO data. The radial
BAO data are consistent with the time-independent cosmological constant model
but do not rule out time-varying dark energy. When we combine radial BAO and
the Kowalski et al. (2008) Union type Ia supernova data we get very tight
constraints on dark energy.Comment: 24 pages, 8 figures, 1 table. Minor changes to match the published
versio
Specific lid-base contacts in the 26s proteasome control the conformational switching required for substrate degradation.
The 26S proteasome is essential for proteostasis and the regulation of vital processes through ATP-dependent degradation of ubiquitinated substrates. To accomplish the multi-step degradation process, the proteasomes regulatory particle, consisting of lid and base subcomplexes, undergoes major conformational changes whose origin is unknown. Investigating the Saccharomyces cerevisiae proteasome, we found that peripheral interactions between the lid subunit Rpn5 and the base AAA+ ATPase ring are important for stabilizing the substrate-engagement-competent state and coordinating the conformational switch to processing states upon substrate engagement. Disrupting these interactions perturbs the conformational equilibrium and interferes with degradation initiation, while later processing steps remain unaffected. Similar defects in early degradation steps are observed when eliminating hydrolysis in the ATPase subunit Rpt6, whose nucleotide state seems to control proteasome conformational transitions. These results provide important insight into interaction networks that coordinate conformational changes with various stages of degradation, and how modulators of conformational equilibria may influence substrate turnover
Determining Quasar Black Hole Mass Functions from their Broad Emission Lines: Application to the Bright Quasar Survey
We describe a Bayesian approach to estimating quasar black hole mass
functions (BHMF) when using the broad emission lines to estimate black hole
mass. We show how using the broad line mass estimates in combination with
statistical techniques developed for luminosity function estimation leads to
statistically biased results. We derive the likelihood function for the BHMF
based on the broad line mass estimates, and derive the posterior distribution
for the BHMF, given the observed data. We develop our statistical approach for
a flexible model where the BHMF is modelled as a mixture of Gaussian functions.
Statistical inference is performed using markov chain monte carlo (MCMC)
methods. Our method has the advantage that it is able to constrain the BHMF
even beyond the survey detection limits at the adopted confidence level,
accounts for measurement errors and the intrinsic uncertainty in broad line
mass estimates, and provides a natural way of estimating the probability
distribution of any quantities derived from the BHMF. We conclude by using our
method to estimate the local active BHMF using the z < 0.5 Bright Quasar Survey
sources. At z = 0.2, the quasar BHMF falls off approximately as a power law
with slope ~ 2 for M_{BH} > 10^8. Our analysis implies that z < 0.5 broad line
quasars have a typical Eddington ratio of ~ 0.4 and a dispersion in Eddington
ratio of < 0.5 dex (abridged).Comment: 25 pages, 14 figures, emulate ApJ style, accepted by Ap
Hubble Space Telescope WFC3 Grism Spectroscopy and Imaging of a Growing Compact Galaxy at z=1.9
We present HST/WFC3 grism spectroscopy of the brightest galaxy at z>1.5 in
the GOODS-South WFC3 Early Release Science grism pointing, covering the
wavelength range 0.9-1.7 micron. The spectrum is of remarkable quality and
shows the redshifted Balmer lines Hbeta, Hgamma, and Hdelta in absorption at
z=1.902, correcting previous erroneous redshift measurements from the
rest-frame UV. The average rest-frame equivalent width of the Balmer lines is
8+-1 Angstrom, which can be produced by a post-starburst stellar population
with a luminosity-weighted age of ~0.5 Gyr. The M/L ratio inferred from the
spectrum implies a stellar mass of ~4x10^11 Msun. We determine the morphology
of the galaxy from a deep WFC3 F160W image. Similar to other massive galaxies
at z~2 the galaxy is compact, with an effective radius of 2.1+-0.3 kpc.
Although most of the light is in a compact core, the galaxy has two red, smooth
spiral arms that appear to be tidally-induced. The spatially-resolved
spectroscopy demonstrates that the center of the galaxy is quiescent and the
surrounding disk is forming stars, as it shows Hbeta in emission. The galaxy is
interacting with a companion at a projected distance of 18 kpc, which also
shows prominent tidal features. The companion has a slightly redder spectrum
than the primary galaxy but is a factor of ~10 fainter and may have a lower
metallicity. It is tempting to interpret these observations as "smoking gun"
evidence for the growth of compact, quiescent high redshift galaxies through
minor mergers, which has been proposed by several recent observational and
theoretical studies. Interestingly both objects host luminous AGNs, as
indicated by their X-ray luminosities, which implies that these mergers can be
accompanied by significant black hole growth. This study illustrates the power
of moderate dispersion, low background near-IR spectroscopy at HST resolution,
which is now available with the WFC3 grism.Comment: 5 pages, 5 figures. Submitted to ApJ Letters
Ages and Metallicities of Hickson Compact Group Galaxies
Hickson Compact Groups (HCGs) constitute an interesting extreme in the range
of environments in which galaxies are located, as the space density of galaxies
in these small groups are otherwise only found in the centres of much larger
clusters. The work presented here uses Lick indices to make a comparison of
ages and chemical compositions of galaxies in HCGs with those in other
environments (clusters, loose groups and the field). The metallicity and
relative abundance of `-elements' show strong correlations with galaxy
age and central velocity dispersion, with similar trends found in all
environments. However, we show that the previously reported correlation between
-element abundance ratios and velocity dispersion disappears when a
full account is taken of the the abundance ratio pattern in the calibration
stars. This correlation is thus found to be an artifact of incomplete
calibration to the Lick system.
Variations are seen in the ranges and average values of age, metallicity and
-element abundance ratios for galaxies in different environments. Age
distributions support the hierarchical formation prediction that field galaxies
are on average younger than their cluster counterparts. However, the ages of
HCG galaxies are shown to be more similar to those of cluster galaxies than
those in the field, contrary to the expectations of current hierarchical
models. A trend for lower velocity dispersion galaxies to be younger was also
seen. This is again inconsistent with hierarchical collapse models, but is
qualitatively consistent with the latest N-body-SPH models based on monolithic
collapse in which star formation continues for many Gyr in low mass halos.Comment: 18 pages. Submitted for publication in MNRA
XMM-Newton X-ray spectroscopy of the high-mass X-ray binary 4U1700-37 at low flux
We present results of a monitoring campaign of the high-mass X-ray binary
system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The
system was observed at four orbital phase intervals, covering 37% of one
3.41-day orbit. The lightcurve includes strong flares, commonly observed in
this source. We focus on three epochs in which the data are not affected by
photon pile up: the eclipse, the eclipse egress and a low-flux interval in the
lightcurve around orbital phase phi ~0.25. The high-energy part of the
continuum is modelled as a direct plus a scattered component, each represented
by a power law with identical photon index (alpha ~1.4), but with different
absorption columns. We show that during the low-flux interval the continuum is
strongly reduced, probably due to a reduction of the accretion rate onto the
compact object. A soft excess is detected in all spectra, consistent with
either another continuum component originating in the outskirts of the system
or a blend of emission lines. Many fluorescence emission lines from
near-neutral species and discrete recombination lines from He- and H-like
species are detected during eclipse and egress. The detection of recombination
lines during eclipse indicates the presence of an extended ionised region
surrounding the compact object. The observed increase in strength of some
emission lines corresponding to higher values of the ionisation parameter xi
further substantiates this conclusion.Comment: 15 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Accuracy of magnetic resonance studies in the detection of chondral and labral lesions in femoroacetabular impingement : systematic review and meta-analysis
Background: Several types of Magnetic resonance imaging (MRI) are commonly used in imaging of femoroacetabular impingement (FAI), however till now there are no clear protocols and recommendations for each type. The aim of this meta-analysis is to detect the accuracy of conventional magnetic resonance imaging (cMRI), direct magnetic resonance arthrography (dMRA) and indirect magnetic resonance arthrography (iMRA) in the diagnosis of chondral and labral lesions in femoroacetabular impingement (FAI).
Methods: A literature search was finalized on the 17th of May 2016 to collect all studies identifying the accuracy of cMRI, dMRA and iMRA in diagnosing chondral and labral lesions associated with FAI using surgical results (arthroscopic or open) as a reference test. Pooled sensitivity and specificity with 95% confidence intervals using a random-effects meta-analysis for MRI, dMRA and iMRA were calculated also area under receiver operating characteristic (ROC) curve (AUC) was retrieved whenever possible where AUC is equivocal to diagnostic accuracy.
Results: The search yielded 192 publications which were reviewed according inclusion and exclusion criteria then 21 studies fulfilled the eligibility criteria for the qualitative analysis with a total number of 828 cases, lastly 12 studies were included in the quantitative meta-analysis. Meta-analysis showed that as regard labral lesions the pooled sensitivity, specificity and AUC for cMRI were 0.864, 0.833 and 0.88 and for dMRA were 0.91, 0.58 and 0.92. While in chondral lesions the pooled sensitivity, specificity and AUC for cMRI were 0.76, 0.72 and 0.75 and for dMRA were 0.75, 0.79 and 0.83, while for iMRA were sensitivity of 0.722 and specificity of 0.917.
Conclusions: The present meta-analysis showed that the diagnostic test accuracy was superior for dMRA when compared with cMRI for detection of labral and chondral lesions. The diagnostic test accuracy was superior for labral lesions when compared with chondral lesions in both cMRI and dMRA. Promising results are obtained concerning iMRA but further studies still needed to fully assess its diagnostic accuracy
Brans-Dicke Theory and primordial black holes in Early Matter-Dominated Era
We show that primordial black holes can be formed in the matter-dominated era
with gravity described by the Brans-Dicke theory. Considering an early
matter-dominated era between inflation and reheating, we found that the
primordial black holes formed during that era evaporate at a quicker than those
of early radiation-dominated era. Thus, in comparison with latter case, less
number of primordial black holes could exist today. Again the constraints on
primordial black hole formation tend towards the larger value than their
radiation-dominated era counterparts indicating a significant enhancement in
the formation of primordial black holes during the matter-dominaed era.Comment: 9 page
Efficacy and safety of enzyme replacement therapy with BMN 110 (elosulfase alfa) for Morquio A syndrome (mucopolysaccharidosis IVA): a phase 3 randomised placebo-controlled study.
ObjectiveTo assess the efficacy and safety of enzyme replacement therapy (ERT) with BMN 110 (elosulfase alfa) in patients with Morquio A syndrome (mucopolysaccharidosis IVA).MethodsPatients with Morquio A aged ≥5 years (N = 176) were randomised (1:1:1) to receive elosulfase alfa 2.0 mg/kg/every other week (qow), elosulfase alfa 2.0 mg/kg/week (weekly) or placebo for 24 weeks in this phase 3, double-blind, randomised study. The primary efficacy measure was 6-min walk test (6MWT) distance. Secondary efficacy measures were 3-min stair climb test (3MSCT) followed by change in urine keratan sulfate (KS). Various exploratory measures included respiratory function tests. Patient safety was also evaluated.ResultsAt week 24, the estimated mean effect on the 6MWT versus placebo was 22.5 m (95 % CI 4.0, 40.9; P = 0.017) for weekly and 0.5 m (95 % CI -17.8, 18.9; P = 0.954) for qow. The estimated mean effect on 3MSCT was 1.1 stairs/min (95 % CI -2.1, 4.4; P = 0.494) for weekly and -0.5 stairs/min (95 % CI -3.7, 2.8; P = 0.778) for qow. Normalised urine KS was reduced at 24 weeks in both regimens. In the weekly dose group, 22.4 % of patients had adverse events leading to an infusion interruption/discontinuation requiring medical intervention (only 1.3 % of all infusions in this group) over 6 months. No adverse events led to permanent treatment discontinuation.ConclusionsElosulfase alfa improved endurance as measured by the 6MWT in the weekly but not qow dose group, did not improve endurance on the 3MSCT, reduced urine KS, and had an acceptable safety profile
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