802 research outputs found
Control of Emi2 activity and stability through Mos-mediated recruitment of PP2A.
Before fertilization, vertebrate eggs are arrested in meiosis II by cytostatic factor (CSF), which holds the anaphase-promoting complex (APC) in an inactive state. It was recently reported that Mos, an integral component of CSF, acts in part by promoting the Rsk-mediated phosphorylation of the APC inhibitor Emi2/Erp1. We report here that Rsk phosphorylation of Emi2 promotes its interaction with the protein phosphatase PP2A. Emi2 residues adjacent to the Rsk phosphorylation site were important for PP2A binding. An Emi2 mutant that retained Rsk phosphorylation but lacked PP2A binding could not be modulated by Mos. PP2A bound to Emi2 acted on two distinct clusters of sites phosphorylated by Cdc2, one responsible for modulating its stability during CSF arrest and one that controls binding to the APC. These findings provide a molecular mechanism for Mos action in promoting CSF arrest and also define an unusual mechanism, whereby protein phosphorylation recruits a phosphatase for dephosphorylation of distinct sites phosphorylated by another kinase
Fractional quantum Hall effect in the absence of Landau levels
It has been well-known that topological phenomena with fractional
excitations, i.e., the fractional quantum Hall effect (FQHE) \cite{Tsui1982}
will emerge when electrons move in Landau levels. In this letter, we report the
discovery of the FQHE in the absence of Landau levels in an interacting fermion
model. The non-interacting part of our Hamiltonian is the recently proposed
topologically nontrivial flat band model on the checkerboard lattice
\cite{sun}. In the presence of nearest-neighboring repulsion (), we find
that at 1/3 filling, the Fermi-liquid state is unstable towards FQHE. At 1/5
filling, however, a next-nearest-neighboring repulsion is needed for the
occurrence of the 1/5 FQHE when is not too strong. We demonstrate the
characteristic features of these novel states and determine the phase diagram
correspondingly.Comment: 6 pages and 4 figure
On the bits per joule optimization in cellular cognitive radio networks
© 2014 IEEE. Cognitive radio has emerged as a promising paradigm to improve the spectrum usage efficiency and to cope with the spectrum scarcity problem through dynamically detecting and re-allocating white spaces in licensed radio band to unlicensed users. However, cognitive radio may cause extra energy consumption because it relies on new and extra technologies and algorithms. The main objective of this work is to enhance the energy efficiency of proposed cellular cognitive radio network (CRN), which is defined as bits/Joule/Hz. In this paper, a typical frame structure of a secondary user (SU) is considered, which consists of sensing and data transmission slots. We analyze and derive the expression for energy efficiency for the proposed CRN as a function of sensing and data transmission duration. The optimal frame structure for maximum bits per joule is investigated under practical network traffic environments. he impact of optimal sensing time and frame length on the achievable energy efficiency, throughput and interference are investigated and verified by simulation results compared with relevant state of art. Our analytical results are in perfect agreement with the empirical results and provide useful insights on how to select sensing length and frame length subject to network environment and required network performance
Circulating Very Small Embryonic-Like Stem Cells in Cardiovascular Disease
Very small embryonic-like cells (VSELs) are a population of stem cells residing in the bone marrow (BM) and several organs, which undergo mobilization into peripheral blood (PB) following acute myocardial infarction and stroke. These cells express markers of pluripotent stem cells (PSCs), such as Oct-4, Nanog, and SSEA-1, as well as early cardiac, endothelial, and neural tissue developmental markers. VSELs can be effectively isolated from the BM, umbilical cord blood, and PB. Peripheral blood and BM-derived VSELs can be expanded in co-culture with C2C12 myoblast feeder layer and undergo differentiation into cells from all three germ layers, including cardiomyocytes and vascular endothelial cells. Isolation of VSLEs using fluorescence-activated cell sorting multiparameter live cell sorting system is dependent on gating strategy based on their small size and expression of PSC and absence of hematopoietic lineage markers. VSELs express early cardiac and endothelial lineages markers (GATA-4, Nkx2.5/Csx, VE-cadherin, and von Willebrand factor), SDF-1 chemokine receptor CXCR4, and undergo rapid mobilization in acute MI and ischemic stroke. Experiments in mice showed differentiation of BM-derived VSELs into cardiac myocytes and effectiveness of expanded and pre-differentiated VSLEs in improvement of left ventricular ejection fraction after myocardial infarction
Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators
Topological crystalline insulators in IV-VI compounds host novel topological
surface states consisting of multi-valley massless Dirac fermions at low
energy. Here we show that strain generically acts as an effective gauge field
on these Dirac fermions and creates pseudo-Landau orbitals without breaking
time-reversal symmetry. We predict the realization of this phenomenon in IV-VI
semiconductor heterostructures, due to a naturally occurring misfit dislocation
array at the interface that produces a periodically varying strain field.
Remarkably, the zero-energy Landau orbitals form a flat band in the vicinity of
the Dirac point, and coexist with a network of snake states at higher energy.
We propose that the high density of states of this flat band gives rise to
interface superconductivity observed in IV-VI semiconductor multilayers at
unusually high temperatures, with non-BCS behavior. Our work demonstrates a new
route to altering macroscopic electronic properties to achieve a partially flat
band, and paves the way for realizing novel correlated states of matter.Comment: Accepted by Nature Physic
Protocol for the 'e-Nudge trial' : a randomised controlled trial of electronic feedback to reduce the cardiovascular risk of individuals in general practice [ISRCTN64828380]
Background: Cardiovascular disease (including coronary heart disease and stroke) is a major
cause of death and disability in the United Kingdom, and is to a large extent preventable, by lifestyle
modification and drug therapy. The recent standardisation of electronic codes for cardiovascular
risk variables through the United Kingdom's new General Practice contract provides an
opportunity for the application of risk algorithms to identify high risk individuals. This randomised
controlled trial will test the benefits of an automated system of alert messages and practice
searches to identify those at highest risk of cardiovascular disease in primary care databases.
Design: Patients over 50 years old in practice databases will be randomised to the intervention
group that will receive the alert messages and searches, and a control group who will continue to
receive usual care. In addition to those at high estimated risk, potentially high risk patients will be
identified who have insufficient data to allow a risk estimate to be made. Further groups identified
will be those with possible undiagnosed diabetes, based either on elevated past recorded blood
glucose measurements, or an absence of recent blood glucose measurement in those with
established cardiovascular disease.
Outcome measures: The intervention will be applied for two years, and outcome data will be
collected for a further year. The primary outcome measure will be the annual rate of cardiovascular
events in the intervention and control arms of the study. Secondary measures include the
proportion of patients at high estimated cardiovascular risk, the proportion of patients with missing
data for a risk estimate, and the proportion with undefined diabetes status at the end of the trial
Awareness, attitudes, and practices related to the swine influenza pandemic among the Saudi public
<p>Abstract</p> <p>Background</p> <p>During an infectious disease outbreak, it is critical to learn as much as possible about the concerns, knowledge, attitudes, and behavior of the public. Such information can be crucial to the improvement of communication efforts by public health officials and clinicians. The aim of this study was to identify awareness, attitudes, and practices related to influenza A (H1N1) among the Saudi public.</p> <p>Methods</p> <p>A cross-sectional study of 1,548 adult subjects recruited from various shopping malls in Riyadh and Jeddah was conducted. All of the subjects were interviewed using a questionnaire that tested their knowledge, attitudes, and use of precautionary measures in relation to the H1N1 influenza pandemic.</p> <p>Results</p> <p>More than half (54.3%, 840/1548) of the participants showed high concern, 43.7%(677/1548) showed a low level of knowledge, and 60.8%(941/1548) had taken minimal or no precautionary measures. After adjusting for other variables, education level was the only significant predictor of the level of concern (p < 0.001), while greater precautionary measures were taken by participants who were male (p < 0.001), older (p = 0.047), better educated (p = 0.04), and more knowledgeable (p < 0.001). More than one-third (38.3%) of participants were not convinced that the MOH reports about the disease were true, and only 16.1% of the participants reported receiving information from health providers.</p> <p>Conclusions</p> <p>High concern did not translate into a higher compliance with precautionary recommendations, possibly due to the low level of knowledge about the disease among the public. Frequent communication between physicians and the public is recommended to help dispel myths about the disease and to spread better information about the role that the public can play in limiting the spread of the disease.</p
Genomic analysis of Pseudomonas putida: genes in a genome island are crucial for nicotine degradation
Nicotine is an important chemical compound in nature that has been regarded as an environmental toxicant causing various preventable diseases. Several bacterial species are adapted to decompose this heterocyclic compound, including Pseudomonas and Arthrobacter. Pseudomonas putida S16 is a bacterium that degrades nicotine through the pyrrolidine pathway, similar to that present in animals. The corresponding late steps of the nicotine degradation pathway in P. putida S16 was first proposed and demonstrated to be from 2,5-dihydroxy-pyridine through the intermediates N-formylmaleamic acid, maleamic acid, maleic acid, and fumaric acid. Genomics of strain S16 revealed that genes located in the largest genome island play a major role in nicotine degradation and may originate from other strains, as suggested by the constructed phylogenetic tree and the results of comparative genomic analysis. The deletion of gene hpo showed that this gene is essential for nicotine degradation. This study defines the mechanism of nicotine degradation
The Sandwell Project: A controlled evaluation of a programme of targeted screening for prevention of cardiovascular disease in primary care
<p>Abstract</p> <p>Background</p> <p>A pilot cardiovascular disease prevention project was implemented in the inner-city West Midlands. It was evaluated by comparing its effectiveness to a control group where full implementation was delayed by a year.</p> <p>Methods</p> <p>Cardiovascular risk factor data were extracted on all untreated patients 35 to 74 years old from electronic medical databases in six general practices. A best estimate of ten-year CVD risk cardiovascular risk was calculated on all patients using the extracted risk factor data. Default risk-factor values were used for all missing risk factor data. High risk patients were thus identified. In four practices a project nurse systematically invited, assessed and referred high risk patients for treatment. Two control practices were provided with a list of their high risk patients. The outcomes were the proportions of untreated high-risk patients who were assessed, identified as eligible for treatment and treated under two strategies for identifying and treating such patients in primary care.</p> <p>Results</p> <p>Of all high-risk patients suitable for inclusion in the project, 40.6% (95% CI: 36.7 to 45.7%) of patients in intervention practices were started on treatment were started on at least one treatment, compared to 12.7% (95% CI: 9.8% to 16.1%) in control practices.</p> <p>Conclusion</p> <p>A strategy using electronic primary care records to identify high risk patients for CVD prevention works best with a process for acting on information, ensuring patients are invited, assessed and treated.</p
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