60 research outputs found
Pressure of thermal excitations in superfluid helium
We find the pressure, due to the thermal excitations of superfluid helium, at
the interface with a solid. The separate contributions of phonons, rotons
and rotons are derived. The pressure due to rotons is shown to be
negative and partially compensates the positive contribution of rotons,
so the total roton pressure is positive but several times less than the
separate and roton contributions. The pressure of the quasiparticle
gas is shown to account for the fountain effect in . An experiment is
proposed to observe the negative pressure due to rotons.Comment: 14 pages, 4 figure
Microorganisms associated with bacterial vaginosis: diversity and clinical and diagnostic significance
Bacterial vaginosis (BV) is the most common infectious non-inflammatory disease in women of reproductive age. The key feature of BV is that in the absence of a specific pathogen, the disease develops against the background of vaginal biotope dysbiosis. According to the opinion of some authors, initially, the main role of BV in the pathogenesis was assigned to the species G. vaginalis. However, using of molecular methods made it possible to significantly expand the range of microorganisms found in women with BV, and to identify Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp., Prevotella spp. as the primary causative agents of BV. A number of studies have confirmed the sexual transmission of BV pathogens, with a new sexual partner being significant risk factors for episodic BV, and sexual contact with the same partner without using barrier methods of contraception for recurrent BV. At the same time, BV-associated bacterias rarely exist as planktonic forms of one species, more often, they thrive in complex polymicrobial communities surrounded by an extracellular matrix, the so-called biofilms. In patients with BV, biofilms are detected in 90% of cases. G. vaginalis and Prevotella bivia are widespread in women with BV and, being the primary colonizers, create a bacterial biofilm, to which secondary colonizers can subsequently join, including A. vaginae, Sneathia spp. and potentially other BVABs. The resistance of bacterias in the biofilm to antimicrobial drugs is 1000 times higher than of planktonic forms, which can lead to chronicity of the infectious process and torpid course of the disease.The aim of this review was analyzing of modern studies on the prevalence, characteristics of opportunistic microorganisms associated with BV, to present their clinical and diagnostic significance and role in the pathogenesis of diseases
Evolution of a pulse of noninteracting quasiparticles with dispersion and initial angular width
The evolution of a pulse of noninteracting quasiparticles, caused by their different velocities
and angular distribution of momenta, is studied theoretically. Equations are found that describe
the shape of the pulse surface at any time. The time of the beginning, end and duration of the density
of the quasiparticle energy flux is determined at a general spatial point. The quasiparticle energy
density is considered at all times and positions, and it is shown that the region of high energy
density, in the middle of the pulse, is equal to the initial energy density under certain conditions.
These theoretical results are discussed in relation to experimental data on the evolution of a pulse
of noninteracting phonons in superfluid helium
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Functional annotation of the transcriptome of Sorghum bicolor in response to osmotic stress and abscisic acid
<p>Abstract</p> <p>Background</p> <p>Higher plants exhibit remarkable phenotypic plasticity allowing them to adapt to an extensive range of environmental conditions. Sorghum is a cereal crop that exhibits exceptional tolerance to adverse conditions, in particular, water-limiting environments. This study utilized next generation sequencing (NGS) technology to examine the transcriptome of sorghum plants challenged with osmotic stress and exogenous abscisic acid (ABA) in order to elucidate genes and gene networks that contribute to sorghum's tolerance to water-limiting environments with a long-term aim of developing strategies to improve plant productivity under drought.</p> <p>Results</p> <p>RNA-Seq results revealed transcriptional activity of 28,335 unique genes from sorghum root and shoot tissues subjected to polyethylene glycol (PEG)-induced osmotic stress or exogenous ABA. Differential gene expression analyses in response to osmotic stress and ABA revealed a strong interplay among various metabolic pathways including abscisic acid and 13-lipoxygenase, salicylic acid, jasmonic acid, and plant defense pathways. Transcription factor analysis indicated that groups of genes may be co-regulated by similar regulatory sequences to which the expressed transcription factors bind. We successfully exploited the data presented here in conjunction with published transcriptome analyses for rice, maize, and Arabidopsis to discover more than 50 differentially expressed, drought-responsive gene orthologs for which no function had been previously ascribed.</p> <p>Conclusions</p> <p>The present study provides an initial assemblage of sorghum genes and gene networks regulated by osmotic stress and hormonal treatment. We are providing an RNA-Seq data set and an initial collection of transcription factors, which offer a preliminary look into the cascade of global gene expression patterns that arise in a drought tolerant crop subjected to abiotic stress. These resources will allow scientists to query gene expression and functional annotation in response to drought.</p
The Ability of Taxonomic Identification of Bifidobacteria Based on the Variable Regions of 16S rRNA Gene
Normal transmission of phonons with anomalous dispersion through the interface of two continuous media
In this work the problem is solved of normal transmission of quasiparticles through the interface
of two continuous media, one of which is quantum fluid. The quantum fluid is described as a
continuous medium with correlations. Within the framework of this approach the dispersion relation
of the quantum fluid Ω(k) can be arbitrary. The integral equation describing it in a half-space
is solved by the Wiener–Hopf method, and its general solution is obtained. This approach is applied
to the dispersion relation of the Bose–Einstein condensate. It is shown that the solutions of
equations of quantum fluid in a half-space are traveling waves deformed near the border by specific
surface standing waves. By means of boundary conditions the general solution in the whole
space is obtained. Expressions for transmission and reflection factors of waves in both directions
are derived, depending on their frequency. The results are important for describing the creation of
helium II phonons on the boundary with a solid, and are of interest for classical acoustics
The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate and herbivore-induced plant volatile production for defense against insect attack
Fatty acid derivatives are of central importance for plant immunity against insect herbivores; however, major regulatory genes and the signals that modulate these defense metabolites are vastly understudied, especially in important agro-economic monocot species. Here we show that products and signals derived from a single Zea mays (maize) lipoxygenase (LOX), ZmLOX10, are critical for both direct and indirect defenses to herbivory. We provide genetic evidence that two 13-LOXs, ZmLOX10 and ZmLOX8, specialize in providing substrate for the green leaf volatile (GLV) and jasmonate (JA) biosynthesis pathways, respectively. Supporting the specialization of these LOX isoforms, LOX8 and LOX10 are localized to two distinct cellular compartments, indicating that the JA and GLV biosynthesis pathways are physically separated in maize. Reduced expression of JA biosynthesis genes and diminished levels of JA in lox10 mutants indicate that LOX10-derived signaling is required for LOX8-mediated JA. The possible role of GLVs in JA signaling is supported by their ability to partially restore wound-induced JA levels in lox10 mutants. The impaired ability of lox10 mutants to produce GLVs and JA led to dramatic reductions in herbivore-induced plant volatiles (HIPVs) and attractiveness to parasitoid wasps. Because LOX10 is under circadian rhythm regulation, this study provides a mechanistic link to the diurnal regulation of GLVs and HIPVs. GLV-, JA- and HIPV-deficient lox10 mutants display compromised resistance to insect feeding, both under laboratory and field conditions, which is strong evidence that LOX10-dependent metabolites confer immunity against insect attack. Hence, this comprehensive gene to agro-ecosystem study reveals the broad implications of a single LOX isoform in herbivore defense. © 2013 Blackwell Publishing Ltd
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