122 research outputs found
Direct imaging of spatial heterogeneities in type II superconductors
Understanding the exotic properties of quantum materials, including
high-temperature superconductors, remains a formidable challenge that demands
direct insights into electronic conductivity. Current methodologies either
capture a bulk average or near-atomically-resolved information, missing direct
measurements at the critical intermediate length scales. Here, using the
superconductor Fe(Se,Te) as a model system, we use low-temperature conductive
atomic force microscopy (cAFM) to bridge this gap. Contrary to the uniform
superconductivity anticipated from bulk assessments, cAFM uncovers micron-scale
conductive intrusions within a relatively insulating matrix. Subsequent
compositional mapping through atom probe tomography, shows that differences in
conductivity correlated with local changes in composition. cAFM, supported by
advanced microscopy and microanalysis, represents a methodological breakthrough
that can be used to navigate the intricate landscape of high-temperature
superconductors and the broader realm of quantum materials. Such fundamental
information is critical for theoretical understanding and future guided design
Inflammatory bowel disease: the role of inflammatory cytokine gene polymorphisms.
The mechanisms responsible for development of inflammatory bowel disease (IBD) have not been fully elucidated, although the main cause of disease pathology is attributed to up-regulated inflammatory processes. The aim of this study was to investigate frequencies of polymorphisms in genes encoding pro-inflammatory and anti-inflammatory markers in IBD patients and controls. We determined genotypes of patients with IBD (n= 172) and healthy controls (n= 389) for polymorphisms in genes encoding various cytokines (interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF), IL-10, IL-1 receptor antagonist). Association of these genotypes to disease incidence and pathophysiology was investigated. No strong association was found with occurrence of IBD. Variation was observed between the ulcerative colitis study group and the control population for the TNF-alpha-308 polymorphism (p= 0.0135). There was also variation in the frequency of IL-6-174 and TNF-alpha-308 genotypes in the ulcerative colitis group compared with the Crohn's disease group (p= 0.01). We concluded that polymorphisms in inflammatory genes are associated with variations in IBD phenotype and disease susceptibility. Whether the polymorphisms are directly involved in regulating cytokine production, and consequently pathophysiology of IBD, or serve merely as markers in linkage disequilibrium with susceptibility genes remains unclear
Effect of Laparoscopic Adjustable Gastric Banding on Metabolic Syndrome and Its Risk Factors in Morbidly Obese Adolescents
We examined the effect of laparoscopic adjustable gastric banding (LAGB) on weight loss, inflammatory markers, and components of the Metabolic Syndrome (MeS) in morbidly obese adolescents and determined if those with MeS lose less weight post-LAGB than those without. Data from 14–18 yr adolescents were obtained at baseline, 6 and 12 months following LAGB. Significant weight loss and improvements in MeS components were observed 6 months and one year following LAGB. The incidence of MeS declined 56.8% after 6 months and 69.6% after 12 months. There was no significant difference in amount of weight lost post-LAGB between those with and without MeS at either timepoint. Correlations between change in weight parameters and components of MeS in those with and without MeS at baseline were examined and found to vary by diagnostic category. LAGB is effective for short-term improvement in weight, inflammatory markers, and components of MeS in morbidly obese adolescents
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Common ERBB2 polymorphisms and risk of breast cancer in a white British population: a case-control study.
INTRODUCTION: About two-thirds of the excess familial risk associated with breast cancer is still unaccounted for and may be explained by multiple weakly predisposing alleles. A gene thought to be involved in low-level predisposition to the disease is ERBB2 (HER2). This gene is involved in cell division, differentiation, and apoptosis and is frequently amplified in breast tumours. Its amplification correlates with poor prognosis. Moreover, the coding polymorphism I655V has previously been associated with an increased risk of breast cancer. METHODS: We aimed to determine if common polymorphisms (frequency >or= 5%) in ERBB2 were associated with breast cancer risk in a white British population. Five single-nucleotide polymorphisms (SNPs) were selected for study: SNP 1 near the promoter, SNP 2 in intron 1, SNP 3 in intron 4, SNP 4 in exon 17 (I655V), and SNP 5 in exon 27 (A1170P). We tested their association with breast cancer in a large case-control study (n = 2192 cases and 2257 controls). RESULTS: There were no differences in genotype frequencies between cases and controls for any of the SNPs examined. To investigate the possibility that a common polymorphism not included in our study might be involved in breast cancer predisposition, we also constructed multilocus haplotypes. Our set of SNPs generated all existing (n = 6) common haplotypes and no differences were seen in haplotype frequencies between cases and controls (P = 0.44). CONCLUSIONS: In our population, common ERBB2 polymorphisms are not involved in predisposition to breast cancer
Evolution of the Most Massive Galaxies to z=0.6: I. A New Method for Physical Parameter Estimation
We use principal component analysis (PCA) to estimate stellar masses, mean
stellar ages, star formation histories (SFHs), dust extinctions and stellar
velocity dispersions for ~290,000 galaxies with stellar masses greater than
$10^{11}Msun and redshifts in the range 0.4<z<0.7 from the Baryon Oscillation
Spectroscopic Survey (BOSS). We find the fraction of galaxies with active star
formation first declines with increasing stellar mass, but then flattens above
a stellar mass of 10^{11.5}Msun at z~0.6. This is in striking contrast to
z~0.1, where the fraction of galaxies with active star formation declines
monotonically with stellar mass. At stellar masses of 10^{12}Msun, therefore,
the evolution in the fraction of star-forming galaxies from z~0.6 to the
present-day reaches a factor of ~10. When we stack the spectra of the most
massive, star-forming galaxies at z~0.6, we find that half of their [OIII]
emission is produced by AGNs. The black holes in these galaxies are accreting
on average at ~0.01 the Eddington rate. To obtain these results, we use the
stellar population synthesis models of Bruzual & Charlot (2003) to generate a
library of model spectra with a broad range of SFHs, metallicities, dust
extinctions and stellar velocity dispersions. The PCA is run on this library to
identify its principal components over the rest-frame wavelength range
3700-5500A. We demonstrate that linear combinations of these components can
recover information equivalent to traditional spectral indices such as the
4000A break strength and HdA, with greatly improved S/N. This method is able to
recover physical parameters such as stellar mass-to-light ratio, mean stellar
age, velocity dispersion and dust extinction from the relatively low S/N BOSS
spectra. We examine the sensitivity of our stellar mass estimates to the input
parameters in our model library and the different stellar population synthesis
models.Comment: 20 pages, 18 Figures, submitted to MNRA
The clustering of galaxies at z~0.5 in the SDSS-III Data Release 9 BOSS-CMASS sample: a test for the LCDM cosmology
We present results on the clustering of 282,068 galaxies in the Baryon
Oscillation Spectroscopic Survey (BOSS) sample of massive galaxies with
redshifts 0.4<z<0.7 which is part of the Sloan Digital Sky Survey III project.
Our results cover a large range of scales from ~0.5 to ~90 Mpc/h. We compare
these estimates with the expectations of the flat LCDM cosmological model with
parameters compatible with WMAP7 data. We use the MultiDark cosmological
simulation together with a simple halo abundance matching technique, to
estimate galaxy correlation functions, power spectra, abundance of subhaloes
and galaxy biases. We find that the LCDM model gives a reasonable description
to the observed correlation functions at z~0.5, which is a remarkably good
agreement considering that the model, once matched to the observed abundance of
BOSS galaxies, does not have any free parameters. However, we find a deviation
(>~10%) in the correlation functions for scales less than ~1 Mpc/h and ~10-40
Mpc/h. A more realistic abundance matching model and better statistics from
upcoming observations are needed to clarify the situation. We also estimate
that about 12% of the "galaxies" in the abundance-matched sample are satellites
inhabiting central haloes with mass M>~1e14 M_sun/h. Using the MultiDark
simulation we also study the real space halo bias b(r) of the matched catalogue
finding that b=2.00+/-0.07 at large scales, consistent with the one obtained
using the measured BOSS projected correlation function. Furthermore, the linear
large-scale bias depends on the number density n of the abundance-matched
sample as b=-0.048-(0.594+/-0.02)*log(n/(h/Mpc)^3). Extrapolating these results
to BAO scales we measure a scale-dependent damping of the acoustic signal
produced by non-linear evolution that leads to ~2-4% dips at ~3 sigma level for
wavenumbers k>~0.1 h/Mpc in the linear large-scale bias.Comment: Replaced to match published version. Typos corrected; 25 pages, 17
figures, 9 tables. To appear in MNRAS. Correlation functions (projected and
redshift-space) and correlation matrices of CMASS presented in Appendix B.
Correlation and covariance data for the combined CMASS sample can be
downloaded from http://www.sdss3.org/science/boss_publications.ph
Effect of Laparoscopic Adjustable Gastric Banding on Metabolic Syndrome and Its Risk Factors in Morbidly Obese Adolescents
We examined the effect of laparoscopic adjustable gastric banding (LAGB) on weight loss, inflammatory markers, and components of the Metabolic Syndrome (MeS) in morbidly obese adolescents and determined if those with MeS lose less weight post-LAGB than those without. Data from 14-18 yr adolescents were obtained at baseline, 6 and 12 months following LAGB. Significant weight loss and improvements in MeS components were observed 6 months and one year following LAGB. The incidence of MeS declined 56.8% after 6 months and 69.6% after 12 months. There was no significant difference in amount of weight lost post-LAGB between those with and without MeS at either timepoint. Correlations between change in weight parameters and components of MeS in those with and without MeS at baseline were examined and found to vary by diagnostic category. LAGB is effective for short-term improvement in weight, inflammatory markers, and components of MeS in morbidly obese adolescents
The 2dF-SDSS LRG and QSO survey: evolution of the clustering of luminous red galaxies since z = 0.6
We present an analysis of the small-to-intermediate scale clustering of
samples of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey and
the 2dF-SDSS LRG and QSO (2SLAQ) survey carefully matched to have the same
rest-frame colours and luminosity. We study the spatial two-point
auto-correlation function in both redshift-space and real-space of a combined
sample of over 10,000 LRGs, which represent the most massive galaxies in the
universe with stellar masses > 10^11 h^-1 M_sun and space densities 10^-4 h^-3
Mpc^-3. We find no significant evolution in the amplitude r_0 of the
correlation function with redshift, but do see a slight decrease in the slope
with increasing redshift over 0.19 < z < 0.55 and scales of 0.32 < r < 32 h^-1
Mpc. We compare our measurements with the predicted evolution of dark matter
clustering and use the halo model to interpret our results. We find that our
clustering measurements are inconsistent (>99.9% significance) with a passive
model whereby the LRGs do not merge with one another; a model with a merger
rate of 7.5 +/- 2.3% from z = 0.55 to z = 0.19 (i.e. an average rate of 2.4%
Gyr^-1) provides a better fit to our observations. Our clustering and number
density measurements are consistent with the hypothesis that the merged LRGs
were originally central galaxies in different haloes which, following the
merger of these haloes, merged to create a single Brightest Cluster Galaxy. In
addition, we show that the small-scale clustering signal constrains the scatter
in halo merger histories. When combined with measurements of the luminosity
function, our results suggest that this scatter is sub-Poisson. While this is a
generic prediction of hierarchical models, it has not been tested before.Comment: 20 pages, replaced with version accepted for publication in MNRA
The association between Self-Reported Medication Adherence scores and systolic blood pressure control: a SPRINT baseline data study
We examined baseline data from the Systolic Blood Pressure Intervention Trial (SPRINT) to investigate whether medication adherence, measured by the 8-item Morisky Medication Adherence Scale (MMAS-8), was associated with systolic blood pressure (SBP) and whether MMAS-8 score and number of antihypertensive medications interacted in influencing SBP. A total of 8435 SPRINT participants were included: 21.2% had low adherence (MMAS-8: 160 mm Hg in 8.8%. In multivariable regression, medium vs. low adherence weakly associated with lower SBP (odds ratio: 1.17; confidence interval: 1.04, 1.31). SPRINT eligibility criteria should be considered when interpreting results. Efforts to understand and enhance adherence are crucial to improve population health, and using self-report instruments might be considered for predicting treatment adherence and response in future efficacy trials and for identifying patients for adherence support in clinical practice
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