828 research outputs found
How do patients from South Asian backgrounds experience life on haemodialysis in the UK? : A multicentre qualitative study
© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.OBJECTIVES: End-stage kidney disease disproportionately affects people of South Asian origin. This study aimed to uncover the lived experiences of this group of patients on centre-based haemodialysis (HD), the most prevalent dialysis modality. DESIGN: The study utilised a qualitative focus group methodology. Seven focus groups were conducted across four NHS Trusts in the UK including three in Gujarati and two each in Punjabi and Urdu. This provided an inclusive opportunity for South Asian patients to contribute in their language of origin. A total of 24 patients participated. Focus groups were facilitated by bilingual project workers and data were forward translated and analysed using thematic analysis. RESULTS: Four themes were identified. This included (1) 'treatment imposition', which comprised of the restrictive nature of HD, the effects of treatment and the feeling of being trapped in an endless process. (2) The 'patient-clinician relationship' centred around the impact of a perceived lack of staff time, and inadequacies in the quality of interactions. (3) 'Coping strategies' highlighted the role of cognitive reappraisal, living in the moment and family support networks in facilitating adjustment. (4) 'Pursuit of transplantation' included equating this form of treatment with restoring normality, alongside cultural factors limiting hopefulness for receiving an organ. CONCLUSIONS: In general, the experiences of South Asian patients receiving HD were not unique to this ethnic group. We did find distinct issues in relation to interactions with healthcare professionals, views on access to transplantation and the importance of family support networks. The study provides useful insights which may help enhance culturally tailored renal care.Peer reviewe
A new method of measuring the cluster peculiar velocity power spectrum
We propose to use spatial correlations of the kinetic Sunyaev-Zeldovich (KSZ)
flux as an estimator of the peculiar velocity power spectrum. In contrast with
conventional techniques, our new method does not require measurements of the
thermal SZ signal or the X-ray temperature. Moreover, this method has the
special advantage that the expected systematic errors are always sub-dominant
to statistical errors on all scales and redshifts of interest. We show that
future large sky coverage KSZ surveys may allow a peculiar velocity power
spectrum estimates of an accuracy reaching ~10%.Comment: 5 pages, 2 figures, MNRAS in Press (doi:
10.1111/j.1365-2966.2008.13454.x
Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments
The low order moments, such as the bulk flow and shear, of the large scale
peculiar velocity field are sensitive probes of the matter density fluctuations
on very large scales. In practice, however, peculiar velocity surveys are
usually sparse and noisy, which can lead to the aliasing of small scale power
into what is meant to be a probe of the largest scales. Previously, we
developed an optimal ``minimum variance'' (MV) weighting scheme, designed to
overcome this problem by minimizing the difference between the measured bulk
flow (BF) and that which would be measured by an ideal survey. Here we extend
this MV analysis to include the shear and octupole moments, which are designed
to have almost no correlations between them so that they are virtually
orthogonal. We apply this MV analysis to a compilation of all major peculiar
velocity surveys, consisting of 4536 measurements. Our estimate of the BF on
scales of ~ 100 Mpc/h has a magnitude of |v|= 416 +/- 78 km/s towards Galactic
l = 282 degree +/- 11 degree and b = 6 degree +/- 6 degree. This result is in
disagreement with LCDM with WMAP5 cosmological parameters at a high confidence
level, but is in good agreement with our previous MV result without an
orthogonality constraint, showing that the shear and octupole moments did not
contaminate the previous BF measurement. The shear and octupole moments are
consistent with WMAP5 power spectrum, although the measurement noise is larger
for these moments than for the BF. The relatively low shear moments suggest
that the sources responsible for the BF are at large distances.Comment: 13 Pages, 7 figures, 4 tables. Some changes to reflect the published
versio
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Early Ultraviolet Observations of Type IIn Supernovae Constrain the Asphericity of Their Circumstellar Material
© 2020. The American Astronomical Society. All rights reserved.. We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common - consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events
A New Heavy Flavor Program for the Future Electron-Ion Collider
The proposed high-energy and high-luminosity Electron-Ion Collider (EIC) will
provide one of the cleanest environments to precisely determine the nuclear
parton distribution functions (nPDFs) in a wide - range. Heavy flavor
production at the EIC provides access to nPDFs in the poorly constrained high
Bjorken- region, allows us to study the quark and gluon fragmentation
processes, and constrains parton energy loss in cold nuclear matter. Scientists
at the Los Alamos National Laboratory are developing a new physics program to
study heavy flavor production, flavor tagged jets, and heavy flavor hadron-jet
correlations in the nucleon/nucleus going direction at the future EIC. The
proposed measurements will provide a unique way to explore the flavor dependent
fragmentation functions and energy loss in a heavy nucleus. They will constrain
the initial-state effects that are critical for the interpretation of previous
and ongoing heavy ion measurements at the Relativistic Heavy Ion Collider and
the Large Hadron Collider. We show an initial conceptual design of the proposed
Forward Silicon Tracking (FST) detector at the EIC, which is essential to carry
out the heavy flavor measurements. We further present initial feasibility
studies/simulations of heavy flavor hadron reconstruction using the proposed
FST.Comment: 6 pages, 5 figures, proceedings for the XLIX International Symposium
on Multiparticle Dynamics (ISMD2019) (9-13 September 2019) conferenc
Average luminosity distance in inhomogeneous universes
The paper studies the correction to the distance modulus induced by
inhomogeneities and averaged over all directions from a given observer. The
inhomogeneities are modeled as mass-compensated voids in random or regular
lattices within Swiss-cheese universes. Void radii below 300 Mpc are
considered, which are supported by current redshift surveys and limited by the
recently observed imprint such voids leave on CMB. The averaging over all
directions, performed by numerical ray tracing, is non-perturbative and
includes the supernovas inside the voids. Voids aligning along a certain
direction produce a cumulative gravitational lensing correction that increases
with their number. Such corrections are destroyed by the averaging over all
directions, even in non-randomized simple cubic void lattices. At low
redshifts, the average correction is not zero but decays with the peculiar
velocities and redshift. Its upper bound is provided by the maximal average
correction which assumes no random cancelations between different voids. It is
described well by a linear perturbation formula and, for the voids considered,
is 20% of the correction corresponding to the maximal peculiar velocity. The
average correction calculated in random and simple cubic void lattices is
severely damped below the predicted maximal one after a single void diameter.
That is traced to cancellations between the corrections from the fronts and
backs of different voids. All that implies that voids cannot imitate the effect
of dark energy unless they have radii and peculiar velocities much larger than
the currently observed. The results obtained allow one to readily predict the
redshift above which the direction-averaged fluctuation in the Hubble diagram
falls below a required precision and suggest a method to extract the background
Hubble constant from low redshift data without the need to correct for peculiar
velocities.Comment: 34 pages, 21 figures, matches the version accepted in JCA
The correlation between C/O ratio, metallicity and the initial WD mass for SNe Ia
In this paper, we want to check whether or not the carbon abundance can be
affected by initial metallicity. We calculated a series of stellar evolution.
We found that when , the carbon abundance is almost independent of
metallicity if it is plotted against the initial WD mass. However, when
, the carbon abundance is not only a function of the initial WD mass,
but also metallicity, i.e. for a given initial WD mass, the higher the
metallicity, the lower the carbon abundance. Based on some previous studies,
i.e. both a high metallicity and a low carbon abundance lead to a lower
production of Ni formed during SN Ia explosion, the effects of the
carbon abundance and the metallicity on the amount of Ni are
enhanced by each other, which may account for the variation of maximum
luminosity of SNe Ia, at least qualitatively. Considering that the central
density of WD before supernova explosion may also play a role on the production
of Ni and the carbon abundance, the metallicity and the central
density are all determined by the initial parameters of progenitor system, i.e.
the initial WD mass, metallicity, orbital period and secondary mass, the amount
of Ni might be a function of the initial parameters. Then, our
results might construct a bridge linking the progenitor model and the explosion
model of SNe Ia.Comment: 7pages, 4 figures, accepted for publication in A&
5-Hydroxymethylation marks a class of neuronal gene regulated by intragenic methylcytosine levels.
AbstractWe recently identified a class of neuronal gene inheriting high levels of intragenic methylation from the mother and maintaining this through later development. We show here that these genes are implicated in basic neuronal functions such as post-synaptic signalling, rather than neuronal development and inherit high levels of 5mC, but not 5hmC, from the mother. 5mC is distributed across the gene body and appears to facilitate transcription, as transcription is reduced in DNA methyltransferase I (Dnmt1) knockout embryonic stem cells as well as in fibroblasts treated with a methyltransferase inhibitor. However in adult brain, transcription is more closely associated with a gain in 5hmC, which occurs without a measurable loss of 5mC. These findings add to growing evidence that there may be a role for 5mC in promoting transcription as well as its classical role in gene silencing
The luminosity of supernovae of type Ia from TRGB distances and the value of H_0
Distances from the tip of the red-giant branch (TRGB) in the halo Population
of galaxies - calibrated through RR Lyr stars as well as tied to Hipparcos
parallaxes and further supported by stellar models - are used to determine the
luminosity of six nearby type Ia supernovae (SN 2011fe, 2007sr, 1998bu, 1989B,
1972E, and 1937C). The result is M_V^corr = -19.41 +/- 0.05. If this value is
applied to 62 SNe Ia with 3000< v < 20,000 km/s a large-scale value of the
Hubble constant follows of H_0 = 64.0 +/- 1.6 +/- 2.0. The SN HST Project gave
H_0 = 62.3 +/- 1.3 +/- 5.0 from ten Cepheid-calibrated SNe Ia (Sandage et al.
2006). The agreement of young Population I (Cepheids) and old, metal-poor
Population II (TRGB) distance indicators is satisfactory. The combined weighted
result is H_0 = 63.7 +/- 2.3 (i.e. +/-3.6%). The result can also be reconciled
with WMAP5 data (Reid et al. 2010).Comment: 9 pages, 3 figures, 3 tables, accepted for publication in Astronomy
and Astrophysic
Recent history of the agriculture of the brazilian Amazon basin: prospects for sustainable development and a first look at the biogeochemical consequences of pasture reformation.
Land-use change for human settlement and agricultural purposes, especially pasture establishment, has caused major impacts on the Amazon Basin's environment. Development of strategies for reformation and restoration of already degraded pastures constitutes the main goal of the authors' research work. For some of this work, a homogeneous area of land in terms of soil characteristics was selected at Nova Vida ranch in Rondônia state to conduct a multidisciplinary experiment, which included agronomic, environmental and economic analyses. Since July 2001, the authors have monitored five treatments: control, herbicide, tillage, no-till rice and no-till soybean, arranged in four blocks. Early results on carbon and nitrogen stocks, nitrogen mineralization, trace-gas fluxes, dissolved organic carbon and microbial biomass are briefly presented
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