347 research outputs found
On the Nature of Trapped-Hole States in CdS Nanocrystals and the Mechanism of their Diffusion
Recent transient absorption experiments on CdS nanorods suggest that
photoexcited holes rapidly trap to the surface of these particles and then
undergo diffusion along the rod surface. In this paper, we present a
semiperiodic DFT model for the CdS nanocrystal surface, analyze it, and comment
on the nature of both the hole-trap states and the mechanism by which the holes
diffuse. Hole states near the top of the valence band form an energetic near
continuum with the bulk, and localize to the non-bonding sp orbitals on
surface sulfur atoms. After localization, the holes form nonadiabatic small
polarons that move between the sulfur orbitals on the surface of the particle
in a series of uncorrelated, incoherent, thermally-activated hops at room
temperature. The surface-trapped holes are deeply in the weak-electronic
coupling limit and, as a result, undergo slow diffusion.Comment: 4 figure
Efficient Photon Upconversion Enabled by Strong Coupling Between Organic Molecules and Quantum Dots
Hybrid structures formed between organic molecules and inorganic quantum dots
can accomplish unique photophysical transformations by taking advantage of
their disparate properties. The electronic coupling between these materials is
typically weak, leading photoexcited charge carriers to spatially localize to a
dot or a molecule at its surface. However, we show that by converting a
chemical linker that covalently binds anthracene molecules to silicon quantum
dots from a carbon-carbon single bond to a double bond, we access a
strong-coupling regime where excited carriers spatially delocalize across both
anthracene and silicon. By pushing the system to delocalize, we design a photon
upconversion system with a higher efficiency (17.2%) and lower threshold
intensity (0.5 W/cm^2) than that of a corresponding weakly-coupled system. Our
results show that strong coupling between molecules and nanostructures achieved
through targeted linking chemistry provides a new route for tailoring
properties in materials for light-driven applications.Comment: 33 pages (20 in main text, 13 in supporting information), 12 figures
(5 in main text, 7 in supporting information
The new IEA Wind Task 36 on Wind Power Forecasting
International audienceWind power forecasts have been used operatively for over 20 years. Despite this fact, there are still several possibilities to improve the forecasts, both from the weather prediction side and from the usage of the forecasts. The new International Energy Agency (IEA) Task on Forecasting for Wind Energy tries to organise international collaboration, among national weather centres with an interest and/or large projects on wind forecast improvements (NOAA, DWD, …), operational forecaster and forecast users. The Task is divided in three work packages: Firstly, a collaboration on the improvement of the scientific basis for the wind predictions themselves. This includes numerical weather prediction model physics, but also widely distributed information on accessible datasets. Secondly, we will be aiming at an international pre-standard (an IEA Recommended Practice) on benchmarking and comparing wind power forecasts, including probabilistic forecasts. This WP will also organise benchmarks, in cooperation with the IEA Task WakeBench. Thirdly, we will be engaging end users aiming at dissemination of the best practice in the usage of wind power predictions
Warped Radion Inflation
We show that the radion in a warped geometry bounded by two branes can have a
potential suitable for inflation. Our construction is based upon a solution
known in string theory as the linear dilaton, in which the back-reaction from a
bulk scalar \Phi is exactly accounted for. The radion, stabilized by \Phi, is
much heavier than the TeV scale and its couplings to the standard model are
much more suppressed than in the usual Randall-Sundrum solution. We present a
new formalism for obtaining approximate time-dependent solutions, based on
perturbing the exact solution to the coupled Einstein and scalar field
equations in the bulk. It allows the radion potential to be computed directly
in terms of the brane potentials for \Phi. We show that simple exponential
potentials on the branes can lead to a 4D radion potential with a flattened
hilltop form, yielding inflation with a spectral index of typically n_s=0.96
and no higher than 0.99. With more complicated brane potentials, the descent
from the hilltop can be a linear potential, giving a tensor-to-scalar ratio as
large as r=0.07 with n_s=0.974. The couplings of the radion to the standard
model particles are dictated by general covariance, so the details of reheating
are explicitly calculable, leading to a reheat temperature of at least 10^7
GeV. The quantum corrections to the inflaton potential from its couplings to
matter are also calculable and are shown to be small, so that the prediction
for the shape of the potential is under theoretical control, even with
superPlanckian field excursions.Comment: 32 pages, 15 figure
Functional characterization of obesity-associated variants involving the α and β isoforms of human SH2B1.
We have previously reported rare variants in sarcoma (Src) homology 2 (SH2) B adaptor protein 1 (SH2B1) in individuals with obesity, insulin resistance, and maladaptive behavior. Here, we identify 4 additional SH2B1 variants by sequencing 500 individuals with severe early-onset obesity. SH2B1 has 4 alternatively spliced isoforms. One variant (T546A) lies within the N-terminal region common to all isoforms. As shown for past variants in this region, T546A impairs SH2B1β enhancement of nerve growth factor-induced neurite outgrowth, and the individual with the T546A variant exhibits mild developmental delay. The other 3 variants (A663V, V695M, and A723V) lie in the C-terminal tail of SH2B1α. SH2B1α variant carriers were hyperinsulinemic but did not exhibit the behavioral phenotype observed in individuals with SH2B1 variants that disrupt all isoforms. In in vitro assays, SH2B1α, like SH2B1β, enhances insulin- and leptin-induced insulin receptor substrate 2 (IRS2) phosphorylation and GH-induced cell motility. None of the variants affect SH2B1α enhancement of insulin- and leptin-induced IRS2 phosphorylation. However, T546A, A663V, and A723V all impair the ability of SH2B1α to enhance GH-induced cell motility. In contrast to SH2B1β, SH2B1α does not enhance nerve growth factor-induced neurite outgrowth. These studies suggest that genetic variants that disrupt isoforms other than SH2B1β may be functionally significant. Further studies are needed to understand the mechanism by which the individual isoforms regulate energy homeostasis and behavior.This work was supported by the Wellcome Trust (098497/Z/
12/Z; 077016/Z/05/Z; 096106/Z/11/Z) (to I.S. Farooqi and L.R.
Pearce), by the Medical Research Council Metabolic Diseases Unit and NIHR Cambridge Biomedical Research Centre (to I.S.
Farooqi, I. Barroso, and S. O’Rahilly) and the Bernard Wolfe
Health Neuroscience Fund (I.S. Farooqi); and by NIH grants
RO1-DK54222 (to C. Carter-Su), RO1-DK065122 and RO1-
DK073601 (to L. Rui), a predoctoral fellowship from the Systems and Integrative Biology Training Grant NIH–T32-GM008322 (to M.E. Doche) and a Rackham Merit Fellowship
from the University of Michigan (to R. Joe). Confocal microscopy was performed using the Morphology and Image Analysis
Core of the Michigan Diabetes Research Center (NIH grant
P60-DK20572).This is the final published version distributed under a Creative Commons Attribution License, which can also be found on the publisher's website at: http://press.endocrine.org/doi/abs/10.1210/en.2014-1264?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubme
The Tryptophan Hydroxylase Inhibitor LX1031 Shows Clinical Benefit in Patients With Nonconstipating Irritable Bowel Syndrome
Serotonin (5-hydroxytryptamine [5-HT]) has an important role in gastrointestinal function. LX1031 is an oral, locally acting, small molecule inhibitor of tryptophan hydroxylase (TPH). Local inhibition of TPH in the gastrointestinal tract might reduce mucosal production of serotonin (5-HT) and be used to treat patients with nonconstipating irritable bowel syndrome (IBS)
Gene-Based Tests of Association
Genome-wide association studies (GWAS) are now used routinely to identify SNPs associated with complex human phenotypes. In several cases, multiple variants within a gene contribute independently to disease risk. Here we introduce a novel Gene-Wide Significance (GWiS) test that uses greedy Bayesian model selection to identify the independent effects within a gene, which are combined to generate a stronger statistical signal. Permutation tests provide p-values that correct for the number of independent tests genome-wide and within each genetic locus. When applied to a dataset comprising 2.5 million SNPs in up to 8,000 individuals measured for various electrocardiography (ECG) parameters, this method identifies more validated associations than conventional GWAS approaches. The method also provides, for the first time, systematic assessments of the number of independent effects within a gene and the fraction of disease-associated genes housing multiple independent effects, observed at 35%–50% of loci in our study. This method can be generalized to other study designs, retains power for low-frequency alleles, and provides gene-based p-values that are directly compatible for pathway-based meta-analysis
Integrated Molecular Characterization of Uterine Carcinosarcoma
SummaryWe performed genomic, epigenomic, transcriptomic, and proteomic characterizations of uterine carcinosarcomas (UCSs). Cohort samples had extensive copy-number alterations and highly recurrent somatic mutations. Frequent mutations were found in TP53, PTEN, PIK3CA, PPP2R1A, FBXW7, and KRAS, similar to endometrioid and serous uterine carcinomas. Transcriptome sequencing identified a strong epithelial-to-mesenchymal transition (EMT) gene signature in a subset of cases that was attributable to epigenetic alterations at microRNA promoters. The range of EMT scores in UCS was the largest among all tumor types studied via The Cancer Genome Atlas. UCSs shared proteomic features with gynecologic carcinomas and sarcomas with intermediate EMT features. Multiple somatic mutations and copy-number alterations in genes that are therapeutic targets were identified
Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation
One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced.
Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI
Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan
This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good
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