3,223 research outputs found
Two-Species Annihilation with Drift: A Model with Continuous Concentration-Decay Exponents
We propose a model for diffusion-limited annihilation of two species, or , where the motion of the particles is subject to a drift. For equal
initial concentrations of the two species, the density follows a power-law
decay for large times. However, the decay exponent varies continuously as a
function of the probability of which particle, the hopping one or the target,
survives in the reaction. These results suggest that diffusion-limited
reactions subject to drift do not fall into a limited number of universality
classes.Comment: 10 pages, tex, 3 figures, also available upon reques
Complete Exact Solution of Diffusion-Limited Coalescence, A + A -> A
Some models of diffusion-limited reaction processes in one dimension lend
themselves to exact analysis. The known approaches yield exact expressions for
a limited number of quantities of interest, such as the particle concentration,
or the distribution of distances between nearest particles. However, a full
characterization of a particle system is only provided by the infinite
hierarchy of multiple-point density correlation functions. We derive an exact
description of the full hierarchy of correlation functions for the
diffusion-limited irreversible coalescence process A + A -> A.Comment: 4 pages, 2 figures (postscript). Typeset with Revte
Aspect-based Sentiment Analysis of Scientific Reviews
Scientific papers are complex and understanding the usefulness of these
papers requires prior knowledge. Peer reviews are comments on a paper provided
by designated experts on that field and hold a substantial amount of
information, not only for the editors and chairs to make the final decision,
but also to judge the potential impact of the paper. In this paper, we propose
to use aspect-based sentiment analysis of scientific reviews to be able to
extract useful information, which correlates well with the accept/reject
decision.
While working on a dataset of close to 8k reviews from ICLR, one of the top
conferences in the field of machine learning, we use an active learning
framework to build a training dataset for aspect prediction, which is further
used to obtain the aspects and sentiments for the entire dataset. We show that
the distribution of aspect-based sentiments obtained from a review is
significantly different for accepted and rejected papers. We use the aspect
sentiments from these reviews to make an intriguing observation, certain
aspects present in a paper and discussed in the review strongly determine the
final recommendation. As a second objective, we quantify the extent of
disagreement among the reviewers refereeing a paper. We also investigate the
extent of disagreement between the reviewers and the chair and find that the
inter-reviewer disagreement may have a link to the disagreement with the chair.
One of the most interesting observations from this study is that reviews, where
the reviewer score and the aspect sentiments extracted from the review text
written by the reviewer are consistent, are also more likely to be concurrent
with the chair's decision.Comment: Accepted in JCDL'2
Enhanced mitochondrial superoxide scavenging does not Improve muscle insulin action in the high fat-fed mouse
Improving mitochondrial oxidant scavenging may be a viable strategy for the treatment of insulin resistance and diabetes. Mice overexpressing the mitochondrial matrix isoform of superoxide dismutase (sod2(tg) mice) and/or transgenically expressing catalase within the mitochondrial matrix (mcat(tg) mice) have increased scavenging of O2(Ë™-) and H2O2, respectively. Furthermore, muscle insulin action is partially preserved in high fat (HF)-fed mcat(tg) mice. The goal of the current study was to test the hypothesis that increased O2(Ë™-) scavenging alone or in combination with increased H2O2 scavenging (mtAO mice) enhances in vivo muscle insulin action in the HF-fed mouse. Insulin action was examined in conscious, unrestrained and unstressed wild type (WT), sod2(tg), mcat(tg) and mtAO mice using hyperinsulinemic-euglycemic clamps (insulin clamps) combined with radioactive glucose tracers following sixteen weeks of normal chow or HF (60% calories from fat) feeding. Glucose infusion rates, whole body glucose disappearance, and muscle glucose uptake during the insulin clamp were similar in chow- and HF-fed WT and sod2(tg) mice. Consistent with our previous work, HF-fed mcat(tg) mice had improved muscle insulin action, however, an additive effect was not seen in mtAO mice. Insulin-stimulated Akt phosphorylation in muscle from clamped mice was consistent with glucose flux measurements. These results demonstrate that increased O2(Ë™-) scavenging does not improve muscle insulin action in the HF-fed mouse alone or when coupled to increased H2O2 scavenging
Prognostic relevance of symptoms versus objective evidence of coronary artery disease in diabetic patients
Aim Little is known about the prognostic significance of silent versus symptomatic coronary artery disease (CAD) in diabetic patients. We therefore assessed the incidence of scintigraphic evidence of CAD in diabetic patients without known CAD and the impact of symptoms and scintigraphic findings on prognosis. Methods and results A consecutive series of 1737 diabetic patients without known CAD underwent dual-isotope myocardial perfusion SPECT (MPS) and 1430 were followed-up for a median of 2 (1-8.5) years. Critical events were defined as myocardial infarction or cardiac death. Objective evidence of CAD was found in 39% of 826 asymptomatic diabetic patients, in 51% of 151 diabetic patients with shortness of breath (SOB), and in 44% of 760 diabetic patients with angina. During follow-up, 98 critical events occurred. Annual critical event rates were 2.2% in asymptomatic, 3.2% in angina, and 7.7% in diabetic patients with shortness of breath (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document} versus other groups). With MPS evidence of CAD, critical event rates increased to 3.4% (asymptomatic), 5.6% (angina), and 13.2% (SOB) (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document} versus no evidence of CAD). Age, hypertension, shortness of breath, scarring and ischaemia were independent predictors of critical events. MPS findings added incremental information to prescan information regarding outcome prediction. Conclusions In asymptomatic diabetic patients, the rate of objective evidence of CAD and annual critical events were similar to those found in diabetic patients with angina. The outcome was three times worse in diabetic patients with shortness of breath. MPS findings were strongly predictive of outcome and proved valuable for risk stratificatio
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Optimization of the IPP-bypass mevalonate pathway and fed-batch fermentation for the production of isoprenol in Escherichia coli.
Isoprenol (3-methyl-3-buten-1-ol) is a drop-in biofuel and a precursor for commodity chemicals. Biological production of isoprenol via the mevalonate pathway has been developed and optimized extensively in Escherichia coli, but high ATP requirements and isopentenyl diphosphate (IPP) toxicity have made it difficult to achieve high titer, yield, and large-scale production. To overcome these limitations, an IPP-bypass pathway was previously developed using the promiscuous activity of diphosphomevalonate decarboxylase, and enabled the production of isoprenol at a comparable yield and titer to the original pathway. In this study, we optimized this pathway, substantially improving isoprenol production. A titer of 3.7 g/L (0.14 g isoprenol per g glucose) was achieved in batch conditions using minimal medium by pathway optimization, and a further optimization of the fed-batch fermentation process enabled an isoprenol titer of 10.8 g/L (yield of 0.105 g/g and maximum productivity of 0.157 g L-1 h-1), which is the highest reported titer for this compound. The substantial increase in isoprenol titer via the IPP-bypass pathway in this study will facilitate progress toward commercialization
Mosaic DNA imports with interspersions of recipient sequence after natural transformation of Helicobacter pylori
Helicobacter pylori colonizes the gastric mucosa of half of the human population, causing gastritis, ulcers, and cancer. H. pylori
is naturally competent for transformation by exogenous DNA, and recombination during mixed infections of one stomach
with multiple H. pylori strains generates extensive allelic diversity. We developed an in vitro transformation protocol to study
genomic imports after natural transformation of H. pylori. The mean length of imported fragments was dependent on the
combination of donor and recipient strain and varied between 1294 bp and 3853 bp. In about 10% of recombinant clones, the
imported fragments of donor DNA were interrupted by short interspersed sequences of the recipient (ISR) with a mean length
of 82 bp. 18 candidate genes were inactivated in order to identify genes involved in the control of import length and
generation of ISR. Inactivation of the antimutator glycosylase MutY increased the length of imports, but did not have a
significant effect on ISR frequency. Overexpression of mutY strongly increased the frequency of ISR, indicating that MutY, while
not indispensable for ISR formation, is part of at least one ISR-generating pathway. The formation of ISR in H. pylori increases
allelic diversity, and contributes to the uniquely low linkage disequilibrium characteristic of this pathogen
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