699 resultados para Lamb wavemodes
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Este documento resume el trabajo realizado por la Mancomunitat de Municipis de l’Àrea Metropolitana de Barcelona (AMB) para la difusión por Internet de la información cartográfica que generan y la colaboración con la Universitat Politècnica de Catalunya (UPC) para migrar el callejero de los municipios que componen el AMB a formato OpenStreetMap (OSM). La difusión gratuita por Internet de la mayor parte, los más utilizados, de los productos que componen el catálogo de Cartografía de la MMAMB pretende facilitar a todos los interesados el acceso a esta infraestructura tan valiosa. Se ha desarrollado también una exportación de los datos que conforman la “Guia de carrers de l’AMB” a OSM. Los objetivos de esta exportación son: la evaluación de la cesión de datos públicos a OSM; el establecimiento de los protocolos necesarios para usar datos procedentes de OSM; la creación de un portal web usando la tecnología de OSM para que los diferentes municipios puedan realizar la edición distribuida de datos cartográficos de AMB; y el uso de herramientas libres para la renderización de mapas, tanto en tiempo real como diferido
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This paper reviews a study to determine the effectiveness of dramatization in teaching social studies to hearing impaired children.
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The Met Office Unified Model is run for a case observed during Intensive Observation Period 18 (IOP18) of the Convective Storms Initiation Project (CSIP). The aims are to identify the physical processes that lead to perturbation growth at the convective scale in response to model-state perturbations and to determine their sensitivity to the character of the perturbations. The case is strongly upper-level forced but with detailed mesoscale/convective-scale evolution that is dependent on smaller-scale processes. Potential temperature is perturbed within the boundary layer. The effects on perturbation growth of both the amplitude and typical scalelength of the perturbations are investigated and perturbations are applied either sequentially (every 30 min throughout the simulation) or at specific times. The direct effects (within one timestep) of the perturbations are to generate propagating Lamb and acoustic waves and produce generally small changes in cloud parameters and convective instability. In exceptional cases a perturbation at a specific gridpoint leads to switching of the diagnosed boundary-layer type or discontinuous changes in convective instability, through the generation or removal of a lid. The indirect effects (during the entire simulation) are changes in the intensity and location of precipitation and in the cloud size distribution. Qualitatively different behaviour is found for strong (1K amplitude) and weak (0.01K amplitude) perturbations, with faster growth after sunrise found only for the weaker perturbations. However, the overall perturbation growth (as measured by the root-mean-square error of accumulated precipitation) reaches similar values at saturation, regardless of the perturbation characterisation.
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Bulk organic VC and C/N ratios from mid-Holocene salt-marsh deposits with sedimentary banding reveal subtle but significant differences between coarse- and fine-grained deposits. These are consistent with findings from seasonally sampled modern silts, and with the interpretation, on physical and palynological grounds, of the fine-grained and coarse-grained components as warm-season and cold-season deposits, respectively. The control is considered to be seasonal variations in the character of the organic matter supplied.
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Remote sensing can potentially provide information useful in improving pollution transport modelling in agricultural catchments. Realisation of this potential will depend on the availability of the raw data, development of information extraction techniques, and the impact of the assimilation of the derived information into models. High spatial resolution hyperspectral imagery of a farm near Hereford, UK is analysed. A technique is described to automatically identify the soil and vegetation endmembers within a field, enabling vegetation fractional cover estimation. The aerially-acquired laser altimetry is used to produce digital elevation models of the site. At the subfield scale the hypothesis that higher resolution topography will make a substantial difference to contaminant transport is tested using the AGricultural Non-Point Source (AGNPS) model. Slope aspect and direction information are extracted from the topography at different resolutions to study the effects on soil erosion, deposition, runoff and nutrient losses. Field-scale models are often used to model drainage water, nitrate and runoff/sediment loss, but the demanding input data requirements make scaling up to catchment level difficult. By determining the input range of spatial variables gathered from EO data, and comparing the response of models to the range of variation measured, the critical model inputs can be identified. Response surfaces to variation in these inputs constrain uncertainty in model predictions and are presented. Although optical earth observation analysis can provide fractional vegetation cover, cloud cover and semi-random weather patterns can hinder data acquisition in Northern Europe. A Spring and Autumn cloud cover analysis is carried out over seven UK sites close to agricultural districts, using historic satellite image metadata, climate modelling and historic ground weather observations. Results are assessed in terms of probability of acquisition probability and implications for future earth observation missions. (C) 2003 Elsevier Ltd. All rights reserved.
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Diebold and Lamb (1997) argue that since the long-run elasticity of supply derived from the Nerlovian model entails a ratio of random variables, it is without moments. They propose minimum expected loss estimation to correct this problem but in so-doing ignore the fact that a non white-noise-error is implicit in the model. We show that, as a consequence the estimator is biased and demonstrate that Bayesian estimation which fully accounts for the error structure is preferable.
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The technique of rapid acidification and alkylation can be used to characterise the redox status of oxidoreductases, and to determine numbers of free cysteine residues within substrate proteins. We have previously used this method to analyse interacting components of the MHC class I pathway, namely ERp57 and tapasin. Here, we have applied rapid acidification alkylation as a novel approach to analysing the redox status of MHC class I molecules. This analysis of the redox status of the MHC class I molecules HLA-A2 and HLA-B27, which is strongly associated with a group of inflammatory arthritic disorders referred to as Spondyloarthropathies, revealed structural and conformational information. We propose that this assay provides a useful tool in the study of in vivo MHC class I structure. (c) 2008 Elsevier B.V. All rights reserved.
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GIMAP (GTPase of the immunity-associated protein family) proteins are a family of putative GTPases believed to be regulators of cell death in lymphomyeloid cells. GIMAP1 was the first reported member of this gene family, identified as a gene up-regulated at the RNA level in the spleens of mice infected with the malarial parasite, Plasmodium chabaudi. Methods A monoclonal antibody against mouse GIMAP1 was developed and was used to analyse the expression of the endogenous protein in tissues of normal mice and in defined sub-populations of cells prepared from lymphoid tissues using flow cytometry. It was also used to assess the expression of GIMAP1 protein after infection and/or immunization of mice with P. chabaudi. Real-time PCR analysis was employed to measure the expression of GIMAP1 for comparison with the protein level analysis. Results GIMAP1 protein expression was detected in all lineages of lymphocytes (T, B, NK), in F4/80+ splenic macrophages and in some lymphoid cell lines. Additional evidence is presented suggesting that the strong expression by mature B cells of GIMAP1 and other GIMAP genes and proteins seen in mice may be a species-dependent characteristic. Unexpectedly, no increase was found in the expression of GIMAP1 in P. chabaudi infected mice at either the mRNA or protein level, and this remained so despite applying a number of variations to the protocol. Conclusion The model of up-regulation of GIMAP1 in response to infection/immunization with P. chabaudi is not a robustly reproducible experimental system. The GIMAP1 protein is widely expressed in lymphoid cells, with an interesting increase in expression in the later stages of B cell development. Alternative approaches will be required to define the functional role of this GTPase in immune cells.
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Individuals are typically co-infected by a diverse community of microparasites (e.g. viruses or protozoa) and macroparasites (e.g. helminths). Vertebrates respond to these parasites differently, typically mounting T helper type 1 (Th1) responses against microparasites and Th2 responses against macroparasites. These two responses may be antagonistic such that hosts face a 'decision' of how to allocate potentially limiting resources. Such decisions at the individual host level will influence parasite abundance at the population level which, in turn, will feed back upon the individual level. We take a first step towards a complete theoretical framework by placing an analysis of optimal immune responses under microparasite-macroparasite co-infection within an epidemiological framework. We show that the optimal immune allocation is quantitatively sensitive to the shape of the trade-off curve and qualitatively sensitive to life-history traits of the host, microparasite and macroparasite. This model represents an important first step in placing optimality models of the immune response to co-infection into an epidemiological framework. Ultimately, however, a more complete framework is needed to bring together the optimal strategy at the individual level and the population-level consequences of those responses, before we can truly understand the evolution of host immune responses under parasite co-infection.
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Wolbachia are bacteria present within the tissues of most filarial nematodes. Filarial nematode survival is known to be affected by immune responses generated during filarial nematode infection and immune responses to Wolbachia can be found in different species harbouring filarial nematode infections, including humans. Using the rodent filarial model Litomosoides sigmodontis, we show that pre-exposure to wolbachia surface protein in a Th1 context (but not in a Th2-context) enhances worm survival on subsequent challenge. This study suggests that despite abundant evidence that pro-inflammatory reactions to the endosymbiont have detrimental effects on the both the nematode and mammalian host, they may under some circumstances be beneficial to the nematode.
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Amid the flurry of grant writing and experimentation, statistical analysis sometimes gets less attention than it requires. Here, we describe fully the considerations that should go into the employment of the statistical two-sample t test.
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Background: Severe malarial anaemia is a major complication of malaria infection and is multifactorial resulting from loss of circulating red blood cells (RBCs) from parasite replication, as well as immune-mediated mechanisms. An understanding of the causes of severe malarial anaemia is necessary to develop and implement new therapeutic strategies to tackle this syndrome of malaria infection. Methods: Using analysis of variance, this work investigated whether parasite-destruction of RBCs always accounts for the severity of malarial anaemia during infections of the rodent malaria model Plasmodium chabaudi in mice of a BALB/c background. Differences in anaemia between two different clones of P. chabaudi were also examined. Results: Circulating parasite numbers were not correlated with the severity of anaemia in either BALB/c mice or under more severe conditions of anaemia in BALB/c RAG2 deficient mice (lacking T and B cells). Mice infected with P. chabaudi clone CB suffered more severe anaemia than mice infected with clone AS, but this was not correlated with the number of parasites in the circulation. Instead, the peak percentage of parasitized RBCs was higher in CB-infected animals than in AS-infected animals, and was correlated with the severity of anaemia, suggesting that the availability of uninfected RBCs was impaired in CB-infected animals. Conclusion: This work shows that parasite numbers are a more relevant measure of parasite levels in P. chabaudi infection than % parasitaemia, a measure that does not take anaemia into account. The lack of correlation between parasite numbers and the drop in circulating RBCs in this experimental model of malaria support a role for the host response in the impairment or destruction of uninfected RBC in P. chabaudi infections, and thus development of acute anaemia in this malaria model.
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ES-62 is a phosphorylcholine-containing glycoprotein secreted by filarial nematodes. This molecule has been shown to reduce the severity of inflammation in collagen-induced arthritis (CIA) in mice, a model of rheumatoid arthritis, via down-regulation of anti-collagen type 1 immune responses. Malaria parasites induce a pro-inflammatory host immune response and many of the symptoms of malaria are immune system-mediated. Therefore we have asked whether the immunomodulatory properties of ES-62 can down-regulate the severity of malaria infection in BALB/c mice infected with Plasmodium chabaudi. We have found that ES-62 has no significant effect on the course of P. chabaudi parasitaemia, and does not significantly affect any of the measures of malaria-induced pathology taken throughout infection.