Showing papers by "Russian Academy of Sciences published in 2005"
Cornell University1, Middle Tennessee State University2, Bielefeld University3, University of California, San Diego4, University of Chicago5, University of Florida6, Sanford-Burnham Institute for Medical Research7, San Diego State University8, Argonne National Laboratory9, Portland State University10, University of Illinois at Urbana–Champaign11, Russian Academy of Sciences12
TL;DR: The subsystem approach is described, the first release of the growing library of populated subsystems is offered, and the SEED is the first annotation environment that supports this model of annotation.
Abstract: The release of the 1000th complete microbial genome will occur in the next two to three years. In anticipation of this milestone, the Fellowship for Interpretation of Genomes (FIG) launched the Project to Annotate 1000 Genomes. The project is built around the principle that the key to improved accuracy in high-throughput annotation technology is to have experts annotate single subsystems over the complete collection of genomes, rather than having an annotation expert attempt to annotate all of the genes in a single genome. Using the subsystems approach, all of the genes implementing the subsystem are analyzed by an expert in that subsystem. An annotation environment was created where populated subsystems are curated and projected to new genomes. A portable notion of a populated subsystem was defined, and tools developed for exchanging and curating these objects. Tools were also developed to resolve conflicts between populated subsystems. The SEED is the first annotation environment that supports this model of annotation. Here, we describe the subsystem approach, and offer the first release of our growing library of populated subsystems. The initial release of data includes 180 177 distinct proteins with 2133 distinct functional roles. This data comes from 173 subsystems and 383 different organisms.
1,896 citations
TL;DR: Three genetic variants of the gene encoding catecholamine-O-methyltransferase determine COMT activity in humans that inversely correlates with pain sensitivity and the risk of developing TMD.
Abstract: Pain sensitivity varies substantially among humans. A significant part of the human population develops chronic pain conditions that are characterized by heightened pain sensitivity. We identified three genetic variants (haplotypes) of the gene encoding catecholamine-O-methyltransferase (COMT) that we designated as low pain sensitivity (LPS), average pain sensitivity (APS) and high pain sensitivity (HPS). We show that these haplotypes encompass 96% of the human population, and five combinations of these haplotypes are strongly associated (P 5 0.0004) with variation in the sensitivity to experimental pain. The presence of even a single LPS haplotype diminishes, by as much as 2.3 times, the risk of developing myogenous temporomandibular joint disorder (TMD), a common musculoskeletal pain condition. The LPS haplotype produces much higher levels of COMT enzymatic activity when compared with the APS or HPS haplotypes. Inhibition of COMT in the rat results in a profound increase in pain sensitivity. Thus, COMT activity substantially influences pain sensitivity, and the three major haplotypes determine COMT activity in humans that inversely correlates with pain sensitivity and the risk of developing TMD.
1,209 citations
TL;DR: In this article, the triplet component of the condensate generated by superconductor-ferromagnet structures is considered, which is odd in frequency and even in momentum, making it insensitive to nonmagnetic impurities.
Abstract: This review considers unusual effects in superconductor-ferromagnet structures, in particular, the triplet component of the condensate generated in those systems. This component is odd in frequency and even in momentum, which makes it insensitive to nonmagnetic impurities. If the exchange field is not homogeneous in the system, the triplet component is not destroyed even by a strong exchange field and can penetrate the ferromagnet over long distances. Some other effects considered here and caused by the proximity effect are enhancement of the Josephson current due to the presence of the ferromagnet, induction of a magnetic moment in superconductors resulting in a screening of the magnetic moment, and formation of periodic magnetic structures due to the influence of the superconductor. Finally, theoretical predictions are compared with existing experiments.
1,144 citations
TL;DR: This review examines the roles of intrinsic disorder in protein network architecture and shows that there are three general ways that intrinsic disorder can contribute: First, intrinsic Disorder can serve as the structural basis for hub protein promiscuity; secondly, intrinsically disordered proteins can bind to structured hub proteins; and thirdly, intrinsic disorderCan provide flexible linkers between functional domains with the linkers enabling mechanisms that facilitate binding diversity.
Abstract: Proteins participate in complex sets of interactions that represent the mechanistic foundation for much of the physiology and function of the cell. These protein-protein interactions are organized into exquisitely complex networks. The architecture of protein-protein interaction networks was recently proposed to be scale-free, with most of the proteins having only one or two connections but with relatively fewer 'hubs' possessing tens, hundreds or more links. The high level of hub connectivity must somehow be reflected in protein structure. What structural quality of hub proteins enables them to interact with large numbers of diverse targets? One possibility would be to employ binding regions that have the ability to bind multiple, structurally diverse partners. This trait can be imparted by the incorporation of intrinsic disorder in one or both partners. To illustrate the value of such contributions, this review examines the roles of intrinsic disorder in protein network architecture. We show that there are three general ways that intrinsic disorder can contribute: First, intrinsic disorder can serve as the structural basis for hub protein promiscuity; secondly, intrinsically disordered proteins can bind to structured hub proteins; and thirdly, intrinsic disorder can provide flexible linkers between functional domains with the linkers enabling mechanisms that facilitate binding diversity. An important research direction will be to determine what fraction of protein-protein interaction in regulatory networks relies on intrinsic disorder.
1,055 citations
TL;DR: The field of complex (dusty) plasmas is reviewed in this paper, where the major types of experimental complex Plasmas are briefly discussed, including grain charging in different regimes, interaction between charged particles, and momentum exchange between different species.
1,003 citations
TL;DR: Modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from a deep olivine-bearing source, and the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plumes edge.
Abstract: More than 50 per cent of the Earth's upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent with a deep olivine-bearing source, because this mineral together with pyroxene buffers both nickel and silicon at lower levels. This can be resolved if the olivine of the mantle peridotite is consumed by reaction with melts derived from recycled oceanic crust, to form a secondary pyroxenitic source. Our modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from this source. In addition, we estimate that the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plume edge. These results are also consistent with volcano volumes, magma volume flux and seismological observations.
966 citations
TL;DR: New methods to automatically build models of macromolecular complexes from high-resolution structures or homology models of their subunits or domains against x-ray or neutron small-angle scattering data are presented and allow one to construct interconnected models without steric clashes.
889 citations
TL;DR: In this paper, the key methods for the preparation of magnetic nanoparticles are described systematically and the experimental data on their properties are analyzed and generalised, as well as the main theoretical views on the magnetism of nanoparticles were considered.
Abstract: The key methods for the preparation of magnetic nanoparticles are described systematically. The experimental data on their properties are analysed and generalised. The main theoretical views on the magnetism of nanoparticles are considered.
802 citations
TL;DR: The most popular methods for determining chain-breaking antioxidant activity (AOA) of food are considered with the aim to estimate their reliability and limitations in this paper, where the main requirements imposed on these methods have been suggested.
787 citations
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TL;DR: Loop heat pipes (LHPs) as mentioned in this paper are two-phase heat-transfer devices with capillary pumping of a working fluid, which can transfer heat efficiency for distances up to several meters at any orientation in the gravity field, or to several tens of meters in a horizontal position.
687 citations
TL;DR: The results of this study demonstrate that intrinsic structural disorder is a distinctive and common characteristic of eukaryotic hub proteins, and that disorder may serve as a determinant of protein interactivity.
Abstract: Recent proteome-wide screening approaches have provided a wealth of information about interacting proteins in various organisms. To test for a potential association between protein connectivity and the amount of predicted structural disorder, the disorder propensities of proteins with various numbers of interacting partners from four eukaryotic organisms (Caenorhabditis elegans, Saccharomyces cerevisiae, Drosophila melanogaster, and Homo sapiens) were investigated. The results of PONDR VL-XT disorder analysis show that for all four studied organisms, hub proteins, defined here as those that interact with ≥10 partners, are significantly more disordered than end proteins, defined here as those that interact with just one partner. The proportion of predicted disordered residues, the average disorder score, and the number of predicted disordered regions of various lengths were higher overall in hubs than in ends. A binary classification of hubs and ends into ordered and disordered subclasses using the consensus prediction method showed a significant enrichment of wholly disordered proteins and a significant depletion of wholly ordered proteins in hubs relative to ends in worm, fly, and human. The functional annotation of yeast hubs and ends using GO categories and the correlation of these annotations with disorder predictions demonstrate that proteins with regulation, transcription, and development annotations are enriched in disorder, whereas proteins with catalytic activity, transport, and membrane localization annotations are depleted in disorder. The results of this study demonstrate that intrinsic structural disorder is a distinctive and common characteristic of eukaryotic hub proteins, and that disorder may serve as a determinant of protein interactivity.
TL;DR: In the wavelength range important for phototherapy (600-860 nm), there are four "active" regions, but peak positions are not exactly the same for all spectra, so exact parameters of peak positions and bandwidths are presented.
Abstract: Objective: The aim of the present work is to analyze available action spectra for various biological responses of HeLa cells irradiated with monochromatic light of 580–860 nm. Background data: Phot...
TL;DR: An overview of the GFP-like proteins developed to date and their most common applications to study living specimens using fluorescence microscopy are given.
TL;DR: In this article, a quantitative description of smectite hydration, based on the relative proportions of different layer types derived from the fitting of experimental X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Li-, Na-, K-, Mg-, Ca-, and Sr-saturated specimens, was studied.
Abstract: Hydration of the <1 μm size fraction of SWy-1 source clay (low-charge montmorillonite) was studied by modeling of X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Li-, Na-, K-, Mg-, Ca-, and Sr-saturated specimens. The quantitative description of smectite hydration, based on the relative proportions of different layer types derived from the fitting of experimental XRD patterns, was consistent with previous reports of smectite hydration. However, the coexistence of smectite layer types exhibiting contrasting hydration states was systematically observed, and heterogeneity rather than homogeneity seems to be the rule for smectite hydration. This heterogeneity can be characterized qualitatively using the standard deviation of the departure from rationality of the 00 l reflection series (ξ), which is systematically larger than 0.4 A when the prevailing layer type accounts for ~70% or less of the total layers (~25% of XRD patterns examined). In addition, hydration heterogeneities are not distributed randomly within smectite crystallites, and models describing these complex structures involve two distinct contributions, each containing different layer types that are interstratifed randomly. As a result, the different layer types are partially segregated in the sample. However, these two contributions do not imply the actual presence of two populations of particles in the sample.
XRD profile modeling also has allowed the refinement of structural parameters, such as the location of interlayer species and the layer thickness corresponding to the different layer types, for all interlayer cations and RH values. From the observed dependence of the latter parameter on the cation ionic potential ( v / r; v = cation valency and r = ionic radius) and on RH, the following equations were derived:
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (1W)\ =\ 12.556\ +\ 0.3525\ {\times}\ ({
u}/\mathit{r}\ {-}\ 0.241)\ {\times}\ ({
u}\ {\times}\ RH\ {-}\ 0.979)\] \end{document}
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (2W)\ =\ 15.592\ +\ 0.6472\ {\times}\ ({
u}/\mathit{r}\ {-}\ 0.839)\ {\times}\ ({
u}\ {\times}\ RH\ {-}\ 1.412)\] \end{document}
which allow the quantification of the increase of layer thickness with increasing RH for both 1W (one water) and 2W (two water) layers. In addition, for 2W layers, interlayer H2O molecules are probably distributed as a unique plane on each side of the central interlayer cation. This plane of H2O molecules is located at ~1.20 A from the central interlayer cation along the c* axis.
TL;DR: The properties of the available photoactivatable fluorescent proteins and their potential applications are discussed.
Abstract: The fluorescence characteristics of photoactivatable proteins can be controlled by irradiating them with light of a specific wavelength, intensity and duration. This provides unique possibilities for the optical labelling and tracking of living cells, organelles and intracellular molecules in a spatio-temporal manner. Here, we discuss the properties of the available photoactivatable fluorescent proteins and their potential applications.
TL;DR: In this paper, the authors present detailed analysis of the dynamics that govern the ultrafast growth of multi-exciton populations in CdSe and PbSe nanocrystals and propose a model of how such populations arise.
Abstract: We have previously demonstrated that absorption of a single photon by a nanocrystal quantum dot can generate multiple excitons with an efficiency of up to 100%. This effect, known as carrier multiplication, should lead to substantial improvements in the performance of a variety of optoelectronic and photocatalytic devices, including solar cells, low-threshold lasers and entangled photon sources. Here we present detailed analysis of the dynamics that govern the ultrafast growth of multi-exciton populations in CdSe and PbSe nanocrystals and propose a model of how such populations arise. Our analysis indicates that the generation of multi-excitons in these systems takes less than 200 fs, which suggests that it is an instantaneous event. We explain this in terms of their direct photogeneration via multiple virtual single-exciton states. This process relies on both the confinement-enhanced Coulomb coupling between single excitons and multi-excitons and the large spectral density of high-energy single- and multi-exciton resonances that occur in semiconductor nanocrystals.
01 Jan 2005
TL;DR: In this paper, a cylindrical quartz tube with an inner diameter of 2mm was used as a model channel, and the downstream part of the tube was heated by an external heat source, and hence the temperature gradient in the axial direction was formed in the tube.
Abstract: Characteristics of premixed combustion in a heated channel with an inner diameter smaller than the conventional quenching distance of the employed mixture were investigated experimentally, analytically, and numerically. A cylindrical quartz tube with an inner diameter of 2 mm was used as a model channel. The downstream part of the tube was heated by an external heat source, and hence the temperature gradient in the axial direction was formed in the middle of the tube. Flat and stationary conventional premixed flames were stabilized at a point in this temperature gradient. In addition to these flames, various other flames that exhibit dynamic behaviors such as cyclic oscillatory motions, and repetitive ignition and extinction were also observed experimentally. These flames with large amplitude oscillatory motion might be utilized as a heat source with high speed temporal temperature variations in microsystems for future application. Another stable flame region in extremely low speed criteria at a mixture velocity of 2–3 cm/s was also experimentally confirmed. This flame was inferred to be an example of mild combustion, and it might also be used as a mild heat source for microdevices. The overall stability criteria of these flame regimes were analytically examined, and the detailed structure of each flame on the stable solution branches was numerically examined by employing 1D computation with detailed chemistry. The two results qualitatively agreed with each other and clarified the mechanism of the present various flames and their dynamic characteristics.
TL;DR: Hints to readily recognize features typical of intrinsic disorder are provided and the principal techniques to assess structural disorder and induced folding are reviewed to point out the necessity of using different approaches and show how information can be broadened by the use of multiples techniques.
Abstract: Intrinsically disordered proteins (IDPs) defy the structure-function paradigm as they fulfill essential biological functions while lacking well-defined secondary and tertiary structures. Conformational and spectroscopic analyses showed that IDPs do not constitute a uniform family, and can be divided into subfamilies as a function of their residual structure content. Residual intramolecular interactions are thought to facilitate binding to a partner and then induced folding. Comprehensive information about experimental approaches to investigate structural disorder and induced folding is still scarce. We herein provide hints to readily recognize features typical of intrinsic disorder and review the principal techniques to assess structural disorder and induced folding. We describe their theoretical principles and discuss their respective advantages and limitations. Finally, we point out the necessity of using different approaches and show how information can be broadened by the use of multiples techniques.
TL;DR: The study of phosphate transport mechanisms and their gene regulation will further the understanding of the intimate interaction between the two symbiotic partners.
TL;DR: The SCORPIO focal reducer as discussed by the authors has been used since the fall of 2000 for observations on the 6-m Special Astrophysical Observatory telescope for direct imaging, long-slit and multislit spectroscopy, spectropolarimetry, and Fabry-Perot panoramic spectrograms.
Abstract: We describe the SCORPIO focal reducer that has been used since the fall of 2000 for observations on the 6-m Special Astrophysical Observatory telescope. We give parameters of the instrument in various observing modes (direct imaging, long-slit and multislit spectroscopy, spectropolarimetry, Fabry-Perot panoramic spectroscopy). Observations of various astronomical objects are used as examples to demonstrate the SCORPIO capabilities.
TL;DR: In this article, the currentvoltage characteristics of tunnel junctions are analyzed under the assumption that the direct electron tunneling represents the dominant conduction mechanism, and the influence of converse piezoelectric effect inherent in ferroelectric materials on the tunnel current is described.
Abstract: We present the concept of ferroelectric tunnel junctions (FTJs). These junctions consist of two metal electrodes separated by a nanometer-thick ferroelectric barrier. The current-voltage characteristics of FTJs are analyzed under the assumption that the direct electron tunneling represents the dominant conduction mechanism. First, the influence of converse piezoelectric effect inherent in ferroelectric materials on the tunnel current is described. The calculations show that the lattice strains of piezoelectric origin modify the current-voltage relationship owing to strain-induced changes of the barrier thickness, electron effective mass, and position of the conduction-band edge. Remarkably, the conductance minimum becomes shifted from zero voltage due to the piezoelectric effect, and a strain-related resistive switching takes place after the polarization reversal in a ferroelectric barrier. Second, we analyze the influence of the internal electric field arising due to imperfect screening of polarization charges by electrons in metal electrodes. It is shown that, for asymmetric FTJs, this depolarizing-field effect also leads to a considerable change of the barrier resistance after the polarization reversal. However, the symmetry of the resulting current-voltage loop is different from that characteristic of the strain-related resistive switching. The crossover from one to another type of the hysteretic curve, which accompanies the increase of FTJ asymmetry, is described taking into account both the strain and depolarizing-field effects. It is noted that asymmetric FTJs with dissimilar top and bottom electrodes are preferable for the non-volatile memory applications because of a larger resistance on/off ratio.
TL;DR: A genome-wide view of changes in cytokinin-responsive transcript abundance of genes that might be functionally relevant for the many biological processes that are governed by cytokinins is presented.
Abstract: Cytokinins are hormones that regulate many developmental and physiological processes in plants. Recent work has revealed that the cytokinin signal is transduced by two-component systems to the nucleus where target genes are activated. Most of the rapid transcriptional responses are unknown. We measured immediate-early and delayed cytokinin responses through genome-wide expression profiling with the Affymetrix ATH1 full genome array (Affymetrix Inc., Santa Clara, CA, USA). Fifteen minutes after cytokinin treatment of 5-day-old Arabidopsis seedlings, 71 genes were upregulated and 11 genes were downregulated. Immediate-early cytokinin response genes include a high portion of transcriptional regulators, among them six transcription factors that had previously not been linked to cytokinin. Five plastid transcripts were rapidly regulated as well, indicating a rapid transfer of the signal to plastids or direct perception of the cytokinin signal by plastids. After 2 h of cytokinin treatment genes coding for transcriptional regulators, signaling proteins, developmental and hormonal regulators, primary and secondary metabolism, energy generation and stress reactions were over-represented. A significant number of the responding genes are known to regulate light (PHYA, PSK1, CIP8, PAT1, APRR), auxin (Aux/IAA), ethylene (ETR2, EIN3, ERFs/EREBPs), gibberellin (GAI, RGA1, GA20 oxidase), nitrate (NTR2, NIA) and sugar (STP1, SUS1) dependent processes, indicating intense crosstalk with environmental cues, other hormones and metabolites. Analysis of cytokinin-deficient 35S:AtCKX1 transgenic seedlings has revealed additional, long-lasting cytokinin-sensitive changes of transcript abundance. Comparative overlay-analysis with the software tool mapman identified previously unknown cytokinin-sensitive metabolic genes, for example in the metabolism of trehalose-6-phosphate. Taken together, we present a genome-wide view of changes in cytokinin-responsive transcript abundance of genes that might be functionally relevant for the many biological processes that are governed by cytokinins.
TL;DR: In this paper, the results of 2D numerical modeling of continental collision involving subduction of the lithospheric mantle demonstrate that geologically plausible stresses and strain rates may result in orogen-scale viscous heat production of 0.1 to > 1 muW m(-3), which is comparable to or even exceeds bulk radiogenic heat production within the crust.
Abstract: Thermal models for Barrovian metamorphism driven by doubling the thickness of the radiogenic crust typically meet difficulty in accounting for the observed peak metamorphic temperature conditions. This difficulty suggests that there is an additional component in the thermal budget of many collisional orogens. Theoretical and geological considerations suggest that viscous heating is a cumulative process that may explain the heat deficit in collision orogens. The results of 2D numerical modelling of continental collision involving subduction of the lithospheric mantle demonstrate that geologically plausible stresses and strain rates may result in orogen-scale viscous heat production of 0.1 to >1 muW m(-3), which is comparable to or even exceeds bulk radiogenic heat production within the crust. Thermally induced buoyancy is responsible for crustal upwelling in large domes with metamorphic temperatures up to 200 degreesC higher than regional background temperatures. Heat is mostly generated within the uppermost mantle, because of large stresses in the highly viscous rocks deforming there. This thermal energy may be transferred to the overlying crust either in the form of enhanced heat flow, or through magmatism that brings heat into the crust advectively. The amplitude of orogenic heating varies with time, with both the amplitude and time-span depending strongly on the coupling between heat production, viscosity and collision strain rate. It is argued that geologically relevant figures are applicable to metamorphic domes such as the Lepontine Dome in the Central Alps. We conclude that deformation-generated viscous dissipation is an important heat source during collisional orogeny and that high metamorphic temperatures as in Barrovian type metamorphism are inherent to deforming crustal regions.
05 Nov 2005-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, high-pressure torsion (HPT) was used to refine Al-3% Mg-0.2% Sc alloy to refine the grain size to ∼ 0.15mm.
Abstract: Disks of an Al–3% Mg–0.2% Sc alloy were processed by high-pressure torsion (HPT) to refine the grain size to ∼0.15 μm. Inspection of the disks after processing revealed a central core region having a relatively coarse and ill-defined microstructure. The size of this core region decreased with increasing numbers of turns in HPT. Measurements showed the hardness increased with increasing applied pressure and/or increasing numbers of turns. In addition, the hardness increased with increasing distance from the center of the disk and stabilized at distances greater than ∼2–3 mm. The values of the saturation hardness in the outer regions of the disks were similar at higher applied pressures and after larger numbers of turns. This saturation hardness was ∼3× the hardness in the solution-treated condition. Within the region of hardness saturation, the microstructure was reasonably homogeneous and consisted of ultrafine grains separated by high-angle grain boundaries. Tensile testing demonstrated the occurrence of high strain rate superplasticity after HPT with elongations to failure that were similar to those obtained in samples of the same alloy processed by equal-channel angular pressing (ECAP).
TL;DR: Evidence is reviewed for a variety of long-distance signaling pathways involving hormones and nutrient ions moving in the xylem sap that allow regulation of plant growth, development and functioning, and particularly shoot water status, as distinct from stress lesions in growth and other processes as a reaction to perturbations such as soil drying.
Abstract: In this article we review evidence for a variety of long-distance signaling pathways involving hormones and nutrient ions moving in the xylem sap. We argue that ABA has a central role to play, at least in root-to-shoot drought stress signaling and the regulation of functioning, growth, and development of plants in drying soil. We also stress the importance of changes in the pH of the leaf cell apoplast as influenced both by edaphic and climatic variation, as a regulator of shoot growth and functioning, and we show how changes in xylem and apoplastic pH can affect the way in which ABA regulates stomatal behavior and growth. The sensitivity to drought of the pH/ABA sensing and signaling mechanism is emphasized. This allows regulation of plant growth, development and functioning, and particularly shoot water status, as distinct from stress lesions in growth and other processes as a reaction to perturbations such as soil drying.
TL;DR: In this article, the leading edge of the radio halo with the bow shock was found to have a slope of α 12 right behind the edge, with quick steepening farther away from the edge.
Abstract: Chandra observations of the merging galaxy cluster A520 reveal a prominent bow shock with M = 21 This is only the second clear example of a substantially supersonic merger shock front in clusters Comparison of the X-ray image with that of the previously known radio halo reveals a coincidence of the leading edge of the halo with the bow shock, offering an interesting experimental setup for determining the role of shocks in the radio halo generation The halo in A520 apparently consists of two spatially distinct parts, the main turbulence-driven component and a cap-like forward structure related to the shock, where the latter may provide preenergized electrons for subsequent turbulent reacceleration The radio edge may be caused by electron acceleration by the shock If so, the synchrotron spectrum should have a slope of α 12 right behind the edge, with quick steepening farther away from the edge Alternatively, if shocks are inefficient accelerators, the radio edge may be explained by an increase in the magnetic field and density of preexisting relativistic electrons due to gas compression In the latter model, there should be radio emission in front of the shock with the same spectrum as that behind it, but 10-20 times fainter If future sensitive radio measurements do not find such preshock emission, then the electrons are indeed accelerated (or reaccelerated) by the shock, and one will be able to determine its acceleration efficiency We also propose a method to estimate the magnetic field strength behind the shock, based on measuring the dependence of the radio spectral slope upon the distance from the shock In addition, the radio edge provides a way to constrain the diffusion speed of the relativistic electrons
TL;DR: In this paper, an analysis of the NOAA AVHRR temporal series since the 1980s showed a decrease in aridity from 1991-2000 compared to 1982-1990, which might have a strong potential impact on the region's natural ecosystems, agricultural crops, and human health.
TL;DR: Amides of GL and conjugates of GL with two amino acid residues and a free 30-COOH function presented up to 70-fold increased activity against SARS-CoV but also increased cytotoxicity resulting in decreased selectivity index.
Abstract: Glycyrrhizin (GL) was shown to inhibit SARS-coronavirus (SARS-CoV) replication in vitro. Here the anti-SARS-CoV activity of 15 GL derivatives was tested. The introduction of 2-acetamido-beta-d-glucopyranosylamine into the glycoside chain of GL resulted in 10-fold increased anti-SARS-CoV activity compared to GL. Amides of GL and conjugates of GL with two amino acid residues and a free 30-COOH function presented up to 70-fold increased activity against SARS-CoV but also increased cytotoxicity resulting in decreased selectivity index.
TL;DR: The model reveals conditions that could prevent rafts from forming, and a mechanism that can cause rafts to remain small, and defines the parameters that control raft merger.
TL;DR: Results, for the first time, suggest that IFN-gamma induces endocytosis of epithelial TJ proteins via RhoA/ROCK-mediated, myosin II-dependent formation of VACs.
Abstract: Disruption of epithelial barrier by proinflammatory cytokines such as IFN-gamma represents a major pathophysiological consequence of intestinal inflammation. We have previously shown that IFN-gamma increases paracellular permeability in model T84 epithelial cells by inducing endocytosis of tight junction (TJ) proteins occludin, JAM-A, and claudin-1. The present study was designed to dissect mechanisms of IFN-gamma-induced endocytosis of epithelial TJ proteins. IFN-gamma treatment of T84 cells resulted in internalization of TJ proteins into large actin-coated vacuoles that originated from the apical plasma membrane and resembled the vacuolar apical compartment (VAC) previously observed in epithelial cells that lose cell polarity. The IFN-gamma dependent formation of VACs required ATPase activity of a myosin II motor but was not dependent on rapid turnover of F-actin. In addition, activated myosin II was observed to colocalize with VACs after IFN-gamma exposure. Pharmacological analyses revealed that formation of VACs and endocytosis of TJ proteins was mediated by Rho-associated kinase (ROCK) but not myosin light chain kinase (MLCK). Furthermore, IFN-gamma treatment resulted in activation of Rho GTPase and induced expressional up-regulation of ROCK. These results, for the first time, suggest that IFN-gamma induces endocytosis of epithelial TJ proteins via RhoA/ROCK-mediated, myosin II-dependent formation of VACs.