1,594 research outputs found

    La noción de sacramento en Hugo de San Víctor

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    Tendency to Maximum Complexity in a Non-Equilibrium Isolated System

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    The time evolution equations of a simplified isolated ideal gas, the "tetrahe- dral" gas, are derived. The dynamical behavior of the LMC complexity [R. Lopez-Ruiz, H. L. Mancini, and X. Calbet, Phys. Lett. A 209, 321 (1995)] is studied in this system. In general, it is shown that the complexity remains within the bounds of minimum and maximum complexity. We find that there are certain restrictions when the isolated "tetrahedral" gas evolves towards equilibrium. In addition to the well-known increase in entropy, the quantity called disequilibrium decreases monotonically with time. Furthermore, the trajectories of the system in phase space approach the maximum complexity.Comment: 22 pages, 0 figures. Published in Phys. Rev. E 63, 066116(9) (2001

    Comparative pan-genome analysis of Piscirickettsia salmonis reveals genomic divergences within genogroups

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    Indexación: Scopus.Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease that seriously affects the salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection. © 2017 Nourdin-Galindo, Sánchez, Molina, Espinoza-Rojas, Oliver, Ruiz, Vargas-Chacoff, Cárcamo, Figueroa, Mancilla, Maracaja-Coutinho and Yañez.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00459/ful

    Formulations of the 3+1 evolution equations in curvilinear coordinates

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    Following Brown, in this paper we give an overview of how to modify standard hyperbolic formulations of the 3+1 evolution equations of General Relativity in such a way that all auxiliary quantities are true tensors, thus allowing for these formulations to be used with curvilinear sets of coordinates such as spherical or cylindrical coordinates. After considering the general case for both the Nagy-Ortiz-Reula (NOR) and the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulations, we specialize to the case of spherical symmetry and also discuss the issue of regularity at the origin. Finally, we show some numerical examples of the modified BSSN formulation at work in spherical symmetry.Comment: 19 pages, 12 figure

    Connectivity, neutral theories and the assessment of species vulnerability to global change in temperate estuaries

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    One of the main adaptation strategies to global change scenarios, aiming to preserve ecosystem functioning and biodiversity, is to maximise ecosystem resilience. The resilience of a species metapopulation can be improved by facilitating connectivity between local populations, which will prevent demographic stochasticity and inbreeding. The objective of this investigation is to estimate the degree of connectivity among estuarine species along the north-eastern Iberian coast, in order to assess community vulnerability to global change scenarios. To address this objective, two connectivity proxy types have been used based upon genetic and ecological drift processes: 1) DNA markers for the bivalve cockle (Cerastoderma edule) and seagrass Zostera noltei, and 2) the decrease in the number of species shared between two sites with geographic distance; neutral biodiversity theory predicts that dispersal limitation modulates this decrease, and this has been explored in estuarine plants and macroinvertebrates. Results indicate dispersal limitation for both saltmarsh plants and seagrass beds community and Z. noltei populations; this suggests they are especially vulnerable to expected climate changes on their habitats. In contrast, unstructured spatial pattern found in macroinvertebrate communities and in C. edule genetic populations in the area suggests that estuarine soft-bottom macroinvertebrates with planktonic larval dispersal strategies may have a high resilience capacity to moderate changes within their habitats. Our findings can help environmental managers to prioritise the most vulnerable species and habitats to be restored

    Modelización de la variabilidad horaria de los contenidos de humedad en hojarasca de Eucalyptus globulus

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    Fuel moisture content is a basic parameter of the present fire danger rating systems and fire behaviour simulation programs. Diurnal Eucalyptus globulus litter fuel moisture content variation patterns in rain free periods are shown in this document. Several situations in relation to sun exposition, wind and nocturnal dead organic fuels dew are considered and the capacity of prediction models which are available in literature in order to follows the patterns is evaluated. It is concluded by emphasizing the good behaviour of a physically based model in the different conditions considered and the appropriate behaviour of particular empirical models to specific situations. Fuel moisture nocturnal latent heat effect is remarked together with the fast sun effect drying up litter which make possible to pass, in a very short time step, from a non inflammable fuel to a situation clearly well-disposed to fire propagation.La humedad de los combustibles es variable fundamental de los sistemas de predicción del riesgo meteorológico de incendio forestal y de simulación del comportamiento de fuego actuales. En este trabajo se muestran patrones de variación de la humedad de la hojarasca de Eucalyptus globulus a lo largo del día en períodos libres de lluvia. Se analizan situaciones diversas en cuanto a exposición al sol, viento y condensación nocturna sobre los restos orgánicos vegetales, y se evalúa la capacidad de modelos de estimación disponibles en la literatura para seguir las tendencias. Se concluye resaltando el buen funcionamiento de un modelo de base física en las distintas condiciones planteadas así como la adecuación de determinados modelos empíricos a situaciones concretas. Se resalta la importancia de la condensación de humedad sobre el combustible así como el rápido efecto desecante del sol que permite pasar, en un br evísimo intervalo de tiempo, de un combustible no inflamable a una situación claramente favorecedora de la propagación

    Thermal impact from a thermoelectric power plant on a tropical coastal lagoon

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    Tropical coastal areas are sensitive ecosystems to climate change, mainly due to sea level rise and increasing water temperatures. Furthermore, they may be subject to numerous stresses, including heat releases from energy production. The Urias coastal lagoon (SE Gulf of California), a subtropical tidal estuary, receives cooling water releases from a thermoelectric power plant, urban and industrial wastes, and shrimp farm discharges. In order to evaluate the plant thermal impact, we measured synchronous temperature time series close to and far from the plant. Furthermore, in order to discriminate the thermal pollution impact from natural variability, we used a high-resolution hydrodynamic model forced by, amongst others, cooling water release as a continuous flow (7.78 m3 s?1) at 6 °C overheating temperature. Model results and field data indicated that the main thermal impact was temporally restricted to the warmest months, spatially restricted to the surface layers (above 0.6 m) and distributed along the shoreline within ?100 m of the release point. The methodology and results of this study can be extrapolated to tropical coastal lagoons that receive heat discharges.<br/

    Grado de conocimiento, tratamiento y control de la hipertensión arterial, hipercolesterolemia y diabetes mellitus en la población general adulta

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    ObjetivosEstimar la prevalencia de los principales factores de riesgo cardiovascular (FRCV) tras la confirmación diagnóstica con el criterio clínico. Analizar el grado de su conocimiento y control, y evaluar la asociación de los FRCV entre sí, estimando qué población es susceptible de intervención.DiseñoEstudio observacional, descriptivo,transversal.EmplazamientoEstudio poblacional realizado en el Área de Salud número 20 de la Comunidad Valenciana (comarca de la Vega Baja del río Segura)PacientesPersonas con ≥ 20 años residentes en dicha área. Muestreo aleatorio polietápico proporcional con definición de cuotas muestrales según el tipo de residencia. Tamaño muestral: 2.550 personas (falta de respuesta en la primera fase en el 26%). Segunda fase del estudio: se realiza la confirmación clínica de los 374 casos detectados de hipertensión arterial (HTA), los 126 de hipercolesterolemia (HCOL) y los 33 de diabetes mellitus (DM).MedicionesSe realiza una entrevista a los pacientes detectados para las tomas de presión arterial a los hipertensos y para practicar la extracción sanguínea a hipercolesterolémicos y diabéticos. Se han utilizado los criterios diagnósticos preconizados por los últimos consensos.ResultadosParticipan 1.886 personas (78,1%). Prevalencias halladas: HTA total, 42 ± 2,2%; diagnosticada, 11,7 ± 1,4%; HCOL total, 26,6 ± 2%; DM total, 9,5 ± 1,3%; tabaquismo: 33,6 ± 2,1% y obesidad: 31,6 ± 2,1%. Grado de control: HTA, 8,6%; HCOL, 21,7%; DM, 56,1%. Asociación de FRCV: el 25,5% no presenta hipertensión, hipercolesterolemia ni fuma.ConclusionesElevada prevalencia FRCV en nuestra área frente a los resultados publicados de ámbito nacional. El tabaquismo resulta menos frecuente que en el resto del país. El grado de control es escaso y la asociación de los FRCV principales para cardiopatía isquémica reflejan que cerca del 75% de la población debe ser intervenida.ObjectivesTo calculate the prevalence of the main cardiovascular risk factors (CVRF) after diagnostic confirmation using clinical criteria. To analyse the degree of understanding and monitoring of these factors and to evaluate the association of CVRF with each other, so estimating who is susceptible to intervention.DesignCross-sectional, descriptive, observational study.SettingPopulation study conducted in Health Area 20 of the Community of Valencia (county of the Low Plain of the River Segura). Patients. People who had lived in this Area for ³20 years. Proportional, multi-stage randomised sampling with definition of sample quotas according to type of residence. Sample size: 2550 people (no reply in first stage: 26%). The second stage involved the clinical confirmation of those identified as suffering from hypertension (HT) (374), hypercholesterolaemia (HCOL) (126), and diabetes (DM) (33).MeasurementsPatients identified were interviewed for taking blood pressure in the case of those with HT, and blood samples in the case of those with HCOL and DM. The diagnostic criteria recommended by the latest consensus were used.Results1886 people (78.1%) took part. Prevalences found: total HT 42±2.2%, diagnosed: 11.7±1.4; total HCOL 26.6±2%; total DM 9.5±1.3%.Tobacco dependency was 33.6±2.1% and Obesity: 31.6±2.1%. Degree of control: HT, 8.6%; HCOL, 21.7%; DM, 56.1%. Association of CVR factors with each other: 25.5% had neither HT nor HCOL and did not smoke.ConclusionsHigh prevalence of CVRF in our area, compared with published national findings.Tobacco dependency is less common than at national level. The degree of control is very low and the association of the main CVRF factors for ischaemic cardiopathy reflect that nearly 75% of the population requires a preventive intervention

    Limitations of positioning systems for developing digital maps and locating vehicles according to the specifications of future driver assistance systems

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    Some advanced driver assistance systems require on-the-lane vehicle positioning on accurate digital maps. The combination of high precision global navigation satellite systems and inertial measurement is the most common technique to carry out this precise positioning since in some areas global positioning systems (GPS) signals are lost or degraded. However, real experimental validation of the navigation algorithms (beyond simulation) is one of the most important shortcomings in the state-of-the-art. In this study, a wide set of real experiments have been carried out on real roads, in urban and rural environments, using an instrumented car. A theoretical approach based on the uncertainty propagation law has been set out to evaluate the errors when using only inertial measurement systems and the maximum distance that can be travelled before exceeding the admissible error limits. Results show that it is better to correct GPS positioning when its signal is degraded than to wait until the signal is definitively lost. Furthermore, inertial measurement systems and GPS receivers of different levels of accuracy have been compared in order to determine whether they are suitable for new assistance applications. Experimental data are consistent with the theoretical approach.The work reported in this paper has been partly funded by the Spanish Ministry of Science and Innovation (SIAC project TRA2007-67786-C02-01 and TRA2007-67786-C02-02) and the CAM project SEGVAUTO.Publicad
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