872 resultados para electronic structure of metals and alloys


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This article introduces a new interface for T-Coffee, a consistency-based multiple sequence alignment program. This interface provides an easy and intuitive access to the most popular functionality of the package. These include the default T-Coffee mode for protein and nucleic acid sequences, the M-Coffee mode that allows combining the output of any other aligners, and template-based modes of T-Coffee that deliver high accuracy alignments while using structural or homology derived templates. These three available template modes are Expresso for the alignment of protein with a known 3D-Structure, R-Coffee to align RNA sequences with conserved secondary structures and PSI-Coffee to accurately align distantly related sequences using homology extension. The new server benefits from recent improvements of the T-Coffee algorithm and can align up to 150 sequences as long as 10,000 residues and is available from both http://www.tcoffee.org and its main mirror http://tcoffee.crg.cat.

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TWEAK (TNF homologue with weak apoptosis-inducing activity) and Fn14 (fibroblast growth factor-inducible protein 14) are members of the tumor necrosis factor (TNF) ligand and receptor super-families. Having observed that Xenopus Fn14 cross-reacts with human TWEAK, despite its relatively low sequence homology to human Fn14, we examined the conservation in tertiary fold and binding interfaces between the two species. Our results, combining NMR solution structure determination, binding assays, extensive site-directed mutagenesis and molecular modeling, reveal that, in addition to the known and previously characterized β-hairpin motif, the helix-loop-helix motif makes an essential contribution to the receptor/ligand binding interface. We further discuss the insight provided by the structural analyses regarding how the cysteine-rich domains of the TNF receptor super-family may have evolved over time. DATABASE: Structural data are available in the Protein Data Bank/BioMagResBank databases under the accession codes 2KMZ, 2KN0 and 2KN1 and 17237, 17247 and 17252. STRUCTURED DIGITAL ABSTRACT: TWEAK binds to hFn14 by surface plasmon resonance (View interaction) xeFn14 binds to TWEAK by enzyme linked immunosorbent assay (View interaction) TWEAK binds to xeFn14 by surface plasmon resonance (View interaction) hFn14 binds to TWEAK by enzyme linked immunosorbent assay (View interaction).

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The epithelial sodium channel (ENaC) in the apical membrane of polarized epithelial cells is the rate-limiting step for Na entry into the cell; in series with the basolateral Na pump, it allows the vectorial transepithelial transport of Na ions. ENaC is expressed in different epithelia like the distal nephron or colon, and the airways epithelium. In the lung ENaC controls the composition and the amount of pulmonary fluid, whereas in the distal nephron ENaC under the control of aldosterone and vasopressin, is essential to adapt the amount of Na+ reabsorbed with the daily sodium intake. Activating mutations of ENaC cause severe disturbances of Na+ homeostasis leading to hypertension in human and in mouse models. Functional expression of ENaC in different cell systems allowed the identification of structural domains of the protein that are essential for channel function and/or modulation of channel activity. Site-directed mutations in specific domains of the channel protein lead to channel hyperactivity or channel loss of function. Knowledge about ENaC structure-function relationships opens new opportunities for development of pharmacological tools for controlling ENaC activity, such as channel activators of potential benefit in the treatment of pulmonary edema, or highly potent ENaC blockers with natriuretic effects.

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The use of electronic control devices has expanded worldwide during the last few years, the most widely used model being the Taser. However, the scientific knowledge about electronic control devices remains limited. We reviewed the medical literature to examine the potential implications of electronic devices in terms of morbidity and mortality, and to identify and evaluate all the existing experimental human studies. A single exposure of an electronic control device on healthy individuals can be assumed to be generally safe, according to 23 prospective human experimental studies and numerous volunteer exposures. In case series, however, electronic control devices could have deleterious effects when used in the field, in particular if persons receive multiple exposures, are intoxicated, show signs of "excited delirium," or present with medical comorbidities. As the use of electronic control devices continues to increase, the controversy about its safety, notably in potentially high-risk individuals, is still a matter of debate. The complications of electronic control device exposure are numerous but often recognizable, usually resulting from barbed dart injuries or from falls. Persons exposed to electronic control devices should therefore be fully examined, and traumatic lesions must be ruled out.

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Detecting the action of selection in natural populations can be achieved using the QST-FST comparison that relies on the estimation of FST with neutral markers, and QST using quantitative traits potentially under selection. QST higher than FST suggests the action of directional selection and thus potential local adaptation. In this article, we apply the QST-FST comparison to four populations of the hermaphroditic freshwater snail Radix balthica located in a floodplain habitat. In contrast to most studies published so far, we did not detect evidence of directional selection for local optima for any of the traits we measured: QST calculated using three different methods was never higher than FST. A strong inbreeding depression was also detected, indicating that outcrossing is probably predominant over selfing in the studied populations. Our results suggest that in this floodplain habitat, local adaptation of R. balthica populations may be hindered by genetic drift, and possibly altered by uneven gene flow linked to flood frequency.

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The flexibility of different regions of HIV-1 protease was examined by using a database consisting of 73 X-ray structures that differ in terms of sequence, ligands or both. The root-mean-square differences of the backbone for the set of structures were shown to have the same variation with residue number as those obtained from molecular dynamics simulations, normal mode analyses and X-ray B-factors. This supports the idea that observed structural changes provide a measure of the inherent flexibility of the protein, although specific interactions between the protease and the ligand play a secondary role. The results suggest that the potential energy surface of the HIV-1 protease is characterized by many local minima with small energetic differences, some of which are sampled by the different X-ray structures of the HIV-1 protease complexes. Interdomain correlated motions were calculated from the structural fluctuations and the results were also in agreement with molecular dynamics simulations and normal mode analyses. Implications of the results for the drug-resistance engendered by mutations are discussed briefly.

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The major antigen on the envelope of extracellular vaccinia virus particles is a polypeptide with an apparent molecular weight of 37,000 (p37K; G. Hiller and K. Weber, J. Virol. 55:651-659, 1985). The gene encoding p37K was mapped in the vaccinia virus genome by hybrid selection of RNA followed by in vitro translation. p37K was then identified among the in vitro translation products by immunoprecipitation with a monoclonal antibody. The gene is located close to the right-hand end of the HindIII F fragment. The corresponding region of the DNA was sequenced, and an open reading frame encoding a polypeptide of 41,748 daltons was observed. The 5' end of the mRNA, as defined by nuclease S1 analysis, maps within only a few nucleotides of the translation initiation codon. Examination of the DNA sequence around the putative initiation site of transcription revealed a characteristic sequence, TAAATG, which includes the ATG translation initiation codon and which is conserved in all but one late gene so far analyzed. It is therefore likely that this sequence is an important regulatory signal for late gene expression in vaccinia virus.

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Spatio-temporal variability in settlement and recruitment, high mortality during the first life-history stages, and selection may determine the genetic structure of cohorts of long-lived marine invertebrates at small scales. We conducted a spatial and temporal analysis of the common Mediterranean Sea urchin Paracentrotus lividus to determine the genetic structure of cohorts at different scales. In Tossa de Mar (NW Mediterranean), recruitment was followed over 5 consecutive springs (2006-2010). In spring 2008, recruits and two-year-old individuals were collected at 6 locations along East and South Iberian coasts separated from 200 to over 1,100 km. All cohorts presented a high genetic diversity based on a fragment of mtCOI. Our results showed a marked genetic homogeneity in the temporal monitoring and a low degree of spatial structure in 2006. In 2008, coupled with an abnormality in the usual circulation patterns in the area, the genetic structure of the southern populations studied changed markedly, with arrival of many private haplotypes. This fact highlights the importance of point events in renewing the genetic makeup of populations, which can only be detected through analysis of the cohort structure coupling temporal and spatial perspectives.

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The optical and electrical recovery processes of the metastable state of the EL2 defect artificially created in n‐type GaAs by boron or oxygen implantation are analyzed at 80 K using optical isothermal transient spectroscopy. In both cases, we have found an inhibition of the electrical recovery and the existence of an optical recovery in the range 1.1-1.4 eV, competing with the photoquenching effect. The similar results obtained with both elements and the different behavior observed in comparison with the native EL2 defect has been related to the network damage produced by the implantation process. From the different behavior with the technological process, it can be deduced that the electrical and optical anomalies have a different origin. The electrical inhibition is due to the existence of an interaction between the EL2 defect and other implantation‐created defects. However, the optical recovery seems to be related to a change in the microscopic metastable state configuration involving the presence of vacancies

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One of the goals of psychological assessment focuses on the adaptation of its instruments to different populations. The objective of this study is to establish the psychometric properties and dimensional structure of the Spanish version of the Coping Responses Inventory- Adult Form (CRI-Adult, Moos, 1993). The following criteria were analyzed: a) descriptive statistics; b) internal consistency reliability (Cronbach"s alpha, and intercorrelations between scales); c) test-retest reliability (4-week interval); d) dimensionality of CRI-Adult (exploratory factor analysis); e) construct validity (confirmatory factor analysis); f) convergent criterion validity (correlations between CRI-Adult and Coping Strategies Indicator, CSI, Amirkhan, 1990), and g) predictive criterion validity (correlations between CRI-Adult, and SCL-90-R, Derogatis, 1983). The results, obtained with 800 adults from Barcelona and surrounding area (334 men and 466 women, aged between 18 to 76 years) indicate that the Spanish version of CRIAdult has satisfactory psychometric properties that allow using this test with guarantee.

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Changes in human lives are studied in psychology, sociology, and adjacent fields as outcomes of developmental processes, institutional regulations and policies, culturally and normatively structured life courses, or empirical accounts. However, such studies have used a wide range of complementary, but often divergent, concepts. This review has two aims. First, we report on the structure that has emerged from scientific life course research by focusing on abstracts from longitudinal and life course studies beginning with the year 2000. Second, we provide a sense of the disciplinary diversity of the field and assess the value of the concept of 'vulnerability' as a heuristic tool for studying human lives. Applying correspondence analysis to 10,632 scientific abstracts, we find a disciplinary divide between psychology and sociology, and observe indications of both similarities of-and differences between-studies, driven at least partly by the data and methods employed. We also find that vulnerability takes a central position in this scientific field, which leads us to suggest several reasons to see value in pursuing theory development for longitudinal and life course studies in this direction.

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The knowledge of a species' population structure is essential for the development of adequate conservation actions as well as for the understanding of its evolution. The population structure is unknown in all species of the Genus Psammodromus, including the Western Sand Racer (Psammodromus occidentalis; a recently described species), the Edward's Sand Racer (P. edwardsianus) and the Spanish Sand Racer (P. hispanicus). In this article, the genetic variability and population structure of Psammodromus edwardsianus, P. hispanicus, and P. occidentalis were studied in the Iberian Peninsula covering their natural geographic distribution. Mitochondrial DNA showed genetically different units in all species with higher genetic variability in their southern populations (latitudinal variation). Genetic differentiation was different among species and contrasted to those of species with similar characteristics. Our results therefore highlight the importance of species-specific studies analysing population structure.