5,080 research outputs found

    Dynamics of wave equations with moving boundary

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    This paper is concerned with long-time dynamics of weakly damped semilinear wave equations defined on domains with moving boundary. Since the boundary is a function of the time variable the problem is intrinsically non-autonomous. Under the hypothesis that the lateral boundary is time-like, the solution operator of the problem generates an evolution process U(t, τ ) : Xτ → Xt, where Xt are timedependent Sobolev spaces. Then, by assuming the domains are expanding, we establish the existence of minimal pullback attractors with respect to a universe of tempered sets defined by the forcing terms. Our assumptions allow nonlinear perturbations with critical growth and unbounded time-dependent external forces.Conselho Nacional de Desenvolvimento Científico e TecnológicoMinisterio de EducaciónMinisterio de Ciencia e Innovació

    Lutein and the C/N as tracers of organic matter in the Palmones River estuary

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    Los pigmentos vegetales han sido usados como bioindicadores de la presencia de organismos fototrópicos en ríos, estuarios y sedimentos marinos actuales y en estudios paleolimnológicos. En el sedimento del estuario río Palmones (Bahía de Algeciras, Sur de España) se ha estudiado las concentraciones de clorofila a y luteína, el índice C/N y el contenido en materia orgánica. Utilizando la concentración de estos dos pigmentos en diferentes profundidades así como el índice de sedimentación(determinado por Rubio et al. En 2003 por el método del 210Pb), se ha determinado el índice de degradación de la luteína y clorofila a en la marisma. La permanencia de la luteína en el sedimento es mayor que la de la clorofila a. Según estos resultados se ha podido discriminar las fuentes de materia orgánicaPlant pigments have been used as biomarkers of the presence of phototrophic organisms in rivers, estuaries and sea sediments in present and in paleolimnological studies. Chlorophyll a and lutein concentration, C/N ratio and organic matter content have been studied in the sediment of the Palmones River estuary (Algeciras Bay, Southern Spain). Using the concentration of these two pigments at different depths, as well as the sedimentation rate (determined by Rubio et al. in 2003 by means of the 210Pb method), lutein and chlorophyll a degradation rate has been determined, in the saltmarsh. Lutein persistence in the sediment was higher than the persistence of chlorophyll a. According to these results, it was possible to discriminate the organic matter source

    Bacteriophages of Shiga toxin-producing Escherichia coli and their contribution to pathogenicity

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    Shiga toxins (Stx) of Shiga toxin-producing Escherichia coli (STEC) are generally encoded in the genome of lambdoid bacteriophages, which spend the most time of their life cycle integrated as prophages in specific sites of the bacterial chromosome. Upon spontaneous induction or induction by chemical or physical stimuli, the stx genes are co-transcribed together with the late phase genes of the prophages. After being assembled in the cytoplasm, and after host cell lysis, mature bacteriophage particles are released into the environment, together with Stx. As members of the group of lambdoid phages, Stx phages share many genetic features with the archetypical temperate phage Lambda, but are heterogeneous in their DNA sequences due to frequent recombination events. In addition to Stx phages, the genome of pathogenic STEC bacteria may contain numerous prophages, which are either cryptic or functional. These prophages may carry foreign genes, some of them related to virulence, besides those necessary for the phage life cycle. Since the production of one or more Stx is considered the major pathogenicity factor of STEC, we aim to highlight the new insights on the contribution of Stx phages and other STEC phages to pathogenicity

    Publicidad y Cultura. La publicidad como homologador cultural

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    Maricruz Alvarado López y Maribel Martín Requero Sevilla, Comunicación Social Ed. Y Publicaciones, 2006

    Monopentamethylcyclopentadienyl isocyanide, amine and imido tantalum(V) complexes. X-ray crystal structure of [TaCp*Cl4(CN-2,6-Me2C6H3)]

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    [TaCp★Cl4](Cp★ = η5-C5Me5) reacts with isocyanides and amines to give the pseudo-octahedral adducts [TaCp★Cl4L] (L = 2,6-Me2C6H3NC, 1; 2,4,6-Me3C6H2NC, 2; tBuNC, 3; or C6H5NH2, 4). Reduction of 1, or alternatively of [TaCp★Cl4] in the presence of stoichiometric amounts of isocyanide, with two equivalents of Na/Hg gives the diamagnetic pseudo-octahedral tantalum(III) complex, [TaCp★Cl2(CN-2,6-Me2C6H3)35. Reaction of 4 with two equivalents of LiNEt2 affords the pseudo-octahedral imido complex [TaCp★Cl2(NC6H5). 6. All the complexes were characterized by usual IR and NMR spectroscopic methods and the molecular structure of I was confirmed by X-ray diffraction methods

    Bacteriophages as fecal pollution indicators

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    Bacteriophages are promising tools for the detection of fecal pollution in different environments, and particularly for viral pathogen risk assessment. Having similar morphological and biological characteristics, bacteriophages mimic the fate and transport of enteric viruses. Enteric bacteriophages, especially phages infecting Escherichia coli (coliphages), have been proposed as alternatives or complements to fecal indicator bacteria. Here, we provide a general overview of the potential use of enteric bacteriophages as fecal and viral indicators in different environments, as well as the available methods for their detection and enumeration, and the regulations for their application

    Microwave-Assisted Synthesis of Substituted Pyrrolo[2,3-d]pyrimidines

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    A new synthetic routes to the triaryl pyrrolo[2,3-d]pyrimidines from common 4,6-dichloropyrimidine have been developed. The triarylated compounds are synthesized by three cross-coupling reactions using three different catalysts. The introduction of C-6-aryl was allowed in two step process using Sonogashira conditions followed by intramolecular cyclization and the Suzuki-Miyaura conditions led the C-4 and C-5 diarylation. This sequence allows a flexible approach to the highly arylated pyrrolopyrimidines containing different aryl group

    Bayesian variable selection and survival modeling: assessing the Most important comorbidities that impact lung and colorectal cancer survival in Spain

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    ancer survival represents one of the main indicators of interest in cancer epidemiology. However, the survival of cancer patients can be affected by several factors, such as comorbidities, that may interact with the cancer biology. Moreover, it is interesting to understand how different cancer sites and tumour stages are affected by different comorbidities. Identifying the comorbidities that affect cancer survival is thus of interest as it can be used to identify factors driving the survival of cancer patients. This information can also be used to identify vulnerable groups of patients with comorbidities that may lead to worst prognosis of cancer. We address these questions and propose a principled selection and evaluation of the effect of comorbidities on the overall survival of cancer patients. In the first step, we apply a Bayesian variable selection method that can be used to identify the comorbidities that predict overall survival. In the second step, we build a general Bayesian survival model that accounts for time-varying effects. In the third step, we derive several posterior predictive measures to quantify the effect of individual comorbidities on the population overall survival. We present applications to data on lung and colorectal cancers from two Spanish population-based cancer registries. The proposed methodology is implemented with a combination of the R-packages mombf and rstan. We provide the code for reproducibility at https://github.com/migariane/BayesVarImpComorbiCancer

    Human Social Behavior and Demography Drive Patterns of Fine-Scale Dengue Transmission in Endemic Areas of Colombia

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    Dengue is known to transmit between humans and A. aegypti mosquitoes living in neighboring houses. Although transmission is thought to be highly heterogeneous in both space and time, little is known about the patterns and drivers of transmission in groups of houses in endemic settings. We carried out surveys of PCR positivity in children residing in 2-block patches of highly endemic cities of Colombia. We found high levels of heterogeneity in PCR positivity, varying from less than 30% in 8 of the 10 patches to 56 and 96%, with the latter patch containing 22 children simultaneously PCR positive (PCR22) for DEN2. We then used an agent-based model to assess the likely eco-epidemiological context of this observation. Our model, simulating daily dengue dynamics over a 20 year period in a single two block patch, suggests that the observed heterogeneity most likely derived from variation in the density of susceptible people. Two aspects of human adaptive behavior were critical to determining this density: external social relationships favoring viral introduction (by susceptible residents or infectious visitors) and immigration of households from non-endemic areas. External social relationships generating frequent viral introduction constituted a particularly strong constraint on susceptible densities, thereby limiting the potential for explosive outbreaks and dampening the impact of heightened vectorial capacity. Dengue transmission can be highly explosive locally, even in neighborhoods with significant immunity in the human population. Variation among neighborhoods in the density of local social networks and rural-to-urban migration is likely to produce significant fine-scale heterogeneity in dengue dynamics, constraining or amplifying the impacts of changes in mosquito populations and cross immunity between serotypes
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