5,598 research outputs found

    Prominent effect of soil network heterogeneity on microbial invasion

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    Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects are explained in terms of a crucial interplay between heterogeneity in microbial spread and heterogeneity in the topology of soil networks. The main influence of network topology on invasion is linked to the existence of long channels in soil networks that may act as bridges for transmission of microorganisms between distant parts of soil

    Prior Design for Dependent Dirichlet Processes: An Application to Marathon Modeling

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    This paper presents a novel application of Bayesian nonparametrics (BNP) for marathon data modeling. We make use of two well-known BNP priors, the single-p dependent Dirichlet process and the hierarchical Dirichlet process, in order to address two different problems. First, we study the impact of age, gender and environment on the runners’ performance. We derive a fair grading method that allows direct comparison of runners regardless of their age and gender. Unlike current grading systems, our approach is based not only on top world records, but on the performances of all runners. The presented methodology for comparison of densities can be adopted in many other applications straightforwardly, providing an interesting perspective to build dependent Dirichlet processes. Second, we analyze the running patterns of the marathoners in time, obtaining information that can be valuable for training purposes. We also show that these running patterns can be used to predict finishing time given intermediate interval measurements. We apply our models to New York City, Boston and London marathons

    Cálculo de los tiempos de circularvección en una población con patología vestibular. Influencia del estímulo visual

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    [corrected] To describe the results obtained for circularvection times (tCV) in a study of the phenomenon of visual-vestibular interaction for a population with vestibular pathology and to analyze differences in its calculation among patients reporting a worsening of their symptoms with visual stimuli. MATERIAL AND METHODS: A detailed case history was taken for all patients, followed by a sensory organization test using computerized dynamic posturography and the calculation of their tCV. RESULTS: The mean tCV results were: tCV2= 6.32+/-3.17 s; tCV3=6.57+/-3.68 s; tCVr=6.27+/-6.02 s. Significant differences were obtained in tCV2 (P=.046) and tCVr (P=.023). CONCLUSIONS: tCV is a diagnostic test using simple tools that can help differentiate patients in whom the visual stimulus is influenced

    CMOS linear laser driver for intermediate frequency over fiber (IFoF) links

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    The main objective of the proposed linear laser driver (LLD) is to reduce signal distortion in an analog direct modulation laser configuration used for intermediate frequency over fiber links. This work draws on an open-loop configuration featuring two differential pair blocks in a cascade arrangement to achieve a bandwidth measurement of 415 MHz at the half-power point, a total harmonic distortion of 4.57% for a fundamental frequency of 100 MHz, and an amplitude of 100 mVpp. The LLD provides a gain of 12.3 dB for a differential output and an output impedance of 46 Ω. The design, layout, and integration correspond to the process design kit for TSMC 65-nm CMOS technology. Experimental results show the advantage over other previously reported laser drivers

    Tailoring activated carbons for the development of specific adsorbents of gasoline vapors

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    The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.This work is supported by the MICINN-FEDER, project CTM2010-18889

    Social network decision making with linguistic trustworthiness based induced OWA operators

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    The file attached to this record is the authors final peer reviewed version. The publisher's version of record can be found by following the DOI link.Classic aggregation operators in group decision making such as the OWA, IOWA, C-IOWA, P-IOWA and I-IOWA have shown to be successful tools in order to provide flexibility in the aggregation of preferences. However, these operators do not take advantage of information related to the interaction between experts. Experts involved in a group decision making problem may have developed opinions about the reliability of other experts' judgements, either because they have previous history of interaction with each other or because they have knowledge that informs them on the reliability of other colleagues in the group in solving decision making problems in the past. In this paper, and within the framework of social network decision making, we present three new social network analysis based IOWA operators that take advantage of the linguistic trustworthiness information gathered from the experts' social network to aggregate the social group preferences. Their use is analysed with simple but illustrative examples

    A Remark on Lorentz Violation at Finite Temperature

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    We investigate the radiatively induced Chern-Simons-like term in four-dimensional field theory at finite temperature. The Chern-Simons-like term is temperature dependent and breaks the Lorentz and CPT symmetries. We find that this term remains undetermined although it can be found unambiguously in different regularization schemes at finite temperature.Comment: To appear in JHEP, 8 pages, 1 eps figure, minor changes and references adde

    Sistema de reconocimiento de habla en español con adaptación al discurso

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    Este trabajo presenta un sistema de reconocimiento automático de habla en idioma español de alto desempeño diseñado para cumplir con dos objetivos. En primer lugar, lograr tasas de reconocimiento que sean comparables a los sistemas que son estado del arte en su tipo. En segundo lugar, evaluar el desempeño de un nuevo método de estimación de modelos de lenguaje propuesto en un trabajo anterior por nuestro grupo. Los resultados muestran un porcentaje de reconocimiento cercano al 90% para un vocabulario de 5000 palabras, lo cual es del mismo orden que otros resultados reportados para sistemas de similares características pero en idioma inglés. También se verificó que el modelo de lenguaje basado en el estimador propuesto por nosotros mejora significativamente el desempeño del sistema comparado con otros dos modelos de lenguaje implementados con los mejores algoritmos conocidos.Eje: Workshop Agentes y sistemas inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI

    Type-1 OWA Unbalanced Fuzzy Linguistic Aggregation Methodology. Application to Eurobonds Credit Risk Evaluation

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.In decision making, a widely used methodology to manage unbalanced fuzzy linguistic information is the linguistic hierarchy (LH), which relies on a linguistic symbolic computational model based on ordinal 2-tuple linguistic representation. However, the ordinal 2-tuple linguistic approach does not exploit all advantages of Zadeh's fuzzy linguistic approach to model uncertainty because the membership function shapes are ignored. Furthermore, the LH methodology is an indirect approach that relies on the uniform distribution of symmetric linguistic assessments. These drawbacks are overcome by applying a fuzzy methodology based on the implementation of the Type-1 Ordered Weighted Average (T1OWA) operator. The T1OWA operator is not a symbolic operator and it allows to directly aggregate membership functions, which in practice means that the T1OWA methodology is suitable for both balanced and unbalanced linguistic contexts and with heterogeneous membership functions. Furthermore, the final output of the T1OWA methodology is always fuzzy and defined in the same domain of the original unbalanced fuzzy linguistic labels, which facilitates its interpretation via a visual joint representation. A case study is presented where the T1OWA operator methodology is used to assess the creditworthiness of European bonds based on real credit risk ratings of individual Eurozone member states modelled as unbalanced fuzzy linguistic labels

    Arabidopsis Heat Stress-Induced Proteins Are Enriched in Electrostatically Charged Amino Acids and Intrinsically Disordered Regions

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    [EN] Comparison of the proteins of thermophilic, mesophilic, and psychrophilic prokaryotes has revealed several features characteristic to proteins adapted to high temperatures, which increase their thermostability. These characteristics include a profusion of disulfide bonds, salt bridges, hydrogen bonds, and hydrophobic interactions, and a depletion in intrinsically disordered regions. It is unclear, however, whether such differences can also be observed in eukaryotic proteins or when comparing proteins that are adapted to temperatures that are more subtly different. When an organism is exposed to high temperatures, a subset of its proteins is overexpressed (heat-induced proteins), whereas others are either repressed (heat-repressed proteins) or remain unaffected. Here, we determine the expression levels of all genes in the eukaryotic model system Arabidopsis thaliana at 22 and 37 degrees C, and compare both the amino acid compositions and levels of intrinsic disorder of heat-induced and heat-repressed proteins. We show that, compared to heat-repressed proteins, heat-induced proteins are enriched in electrostatically charged amino acids and depleted in polar amino acids, mirroring thermophile proteins. However, in contrast with thermophile proteins, heat-induced proteins are enriched in intrinsically disordered regions, and depleted in hydrophobic amino acids. Our results indicate that temperature adaptation at the level of amino acid composition and intrinsic disorder can be observed not only in proteins of thermophilic organisms, but also in eukaryotic heat-induced proteins; the underlying adaptation pathways, however, are similar but not the same.D.A.-P. and F.F. were supported by funds from the University of Nevada, Reno, and by pilot grants from Nevada INBRE (P20GM103440) and the Smooth Muscle Plasticity COBRE from the University of Nevada, Reno (5P30GM110767-04), both funded by the National Institute of General Medical Sciences (National Institutes of Health). M.X.R.-G. and M.A.F. were supported by grants from Science Foundation Ireland (12/IP/1637) and the Spanish Ministerio de Economia y Competitividad, Spain (MINECO-FEDER; BFU201236346 and BFU2015-66073-P) to MAF. MXRG was supported by a JAE DOC fellowship from the MINECO, Spain. 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