1,437 research outputs found

    Statistical mechanics and the description of the early universe II. Principle of detailed balance and primordial 4He formation

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    If the universe is slightly non-extensive, and the distribution functions are not exactly given by those of Boltzmann-Gibbs, the primordial production of light elements will be non-trivially modified. In particular, the principle of detailed balance (PDB), of fundamental importance in the standard analytical analysis, is no longer valid, and a non-extensive correction appears. This correction is computed and its influence is studied and compared with previous works, where, even when the universe was considered as an slightly non-extensive system, the PDB was assumed valid. We analytically track the formation of Helium and Deuterium, and study the kind of deviation one could expect from the standard regime. The correction to the capture time, the moment in which Deuterium can no longer be substantially photo-disintegrated, is also presented. This allows us to take into account the process of the free decay of neutrons, which was absent in all previous treatments of the topic. We show that even when considering a first (linear) order correction in the quantum distribution functions, the final output on the primordial nucleosynthesis yields cannot be reduced to a linear correction in the abundances. We finally obtain new bounds upon the non-extensive parameter, both comparing the range of physical viability of the theory, and using the latest observational data.Comment: 24 pages, to appear in Physica A (2001

    Spontaneous Symmetry Breaking for Scalar QED with Non-minimal Chern-Simons Coupling

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    We investigate the two-loop effective potential for both minimally and non-minimally coupled Maxwell-Chern-Simons theories. The non-minimal gauge interaction represents the magnetic moment interaction between a charged scalar and the electromagnetic field. In a previous paper we have shown that the two loop effective potential for this model is renormalizable with an appropriate choice of the non-minimal coupling constant. We carry out a detailed analysis of the spontaneous symmetry breaking induced by radiative corrections. As long as the renormalization point for all couplings is chosen to be the true minimum of the effective potential, both models predict the presence of spontaneous symmetry breaking. Two loop corrections are small compared to the one loop result, and thus the symmetry breaking is perturbatively stable.Comment: Revtex 25 pages, 9 figure

    La alimentación de los inmigrantes marroquíes de la Comunidad de Madrid: factores que influyen en la selección de los alimentos

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    ObjetivoConocer las características alimentarias de la población marroquí de la Comunidad de Madrid, explorando los factores que pueden estar influyendo en la selección de alimentos.DiseñoEstudio transversal de base poblacional, muestreo por conglomerados bietápico.EmplazamientoÁrea Sanitaria 6 de la Comunidad de Madrid.ParticipantesInmigrantes marroquíes, mayores de 14 años, con un tiempo de estancia en España ≥ 3 meses.IntervencionesEntrevista que incluye un recordatorio de 24 horas de los alimentos consumidos. Análisis descriptivo y regresión logística con SPSS 8.0 para Windows.Mediciones y resultados principalesLos factores que más influyen en la selección de los alimentos son la edad, el hecho de vivir o no con la pareja y el hecho de saber leer y escribir en español. El sexo y el tiempo de estancia en España tienen una muy escasa influencia en la selección de alimentos.ConclusionesLos resultados contrastan con los obtenidos en estudios realizados en otros países, observando en nuestro caso una mejora de los hábitos y una dieta más variada y equilibrada entre aquellas personas con una aculturación más avanzada, de mayor edad o que viven con su pareja. Las personas que llevan menos tiempo en España siguen una dieta menos variada, que podría dar lugar a problemas nutricionales importantes.ObjectivesTo describe the main characteristics of the diet of Marrocan immigrants in the Autonomous Community of Madrid, and to explore the factors that may influence their selection of foods.DesignCross-sectional study. Two-stage cluster sampling of 179 immigrants.SettingHealth Area number 6 of the Autonomous Community of Madrid.ParticipantsMarrocan immigrants, older than 14 years of age who had lived in Spain more than 3 months.InterventionsPersonal interview including a 24-hours recall of food consumption. Descriptive analysis and logistic regression using SPSS 8.0 for Windows.ResultsThe factors that have a larger influence in the food consumed are the age of the person, whether the person lives in a couple or not, and whether the person is able to read and write in Spanish. Gender and number of years living in Spain had very limited or no influence in the food items referred to as consumed by the person.ConclusionsThe results of our study contrast with findings from studies conducted in other countries. The diet of the immigrants in our study would seem to become more varied and balanced, and therefore improve, with the progression of the acculturation process, with age and in people who live with their partners. People who have migrated recently have a less varied diet and may be proned to suffer nutritional defficiences

    Qualidade e Segurança Alimentar em unidades fabris produtoras de enchidos no Alentejo

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    Portugal, tal como outros países do Mediterrâneo, tem uma grande diversidade de enchidos secos fermentados. A produção tradicional de enchidos é muito diversa e os produtos possuem caraterísticas organoléticas muito particulares que agradam aos consumidores. Estas caraterísticas sensoriais estão relacionadas não só com os processos de fabrico, mas também com a flora microbiana autóctone. Por outro lado, a segurança dos produtos fermentados nem sempre se atinge com facilidade uma vez que no seu processamento não existe uma etapa que elimine os agentes patogénicos. Neste tipo de produtos estão normalmente presentes bactérias benéficas como estafilococos coagulase negativos e bactérias do ácido lático (BAL). Estes grupos bacterianos são responsáveis pelo sabor e aroma caraterísticos dos enchidos e também por aumentarem o seu tempo de vida de prateleira. De um modo geral, as estirpes dos referidos grupos bacterianos têm um papel muito importante para a segurança alimentar porque, se bem adaptados aos substratos, por exclusão competitiva condicionam o crescimento de microrganismos patogénicos e alterantes. As BAL são particularmente úteis pela sua capacidade produtora de ácido láctico e, em alguns casos, de bacteriocinas geralmente ativas contra agentes patogénicos, tais como Escherichia coli, Listeria monocytogenes e Salmonella spp., enquanto os estafilococos coagulase negativos são principalmente redutores de nitratos, contribuindo assim para o desenvolvimento da cor. O objetivo deste trabalho foi determinar a ocorrência de Salmonella spp., L. monocytogenes e E. coli em diferentes superfícies (parede da sala de enchimento, picadora, misturadora e enchedora) de três fábricas, bem como em enchidos tradicionais Portugueses em diferentes fases de cura: massa, meio da cura e produto final. Adicionalmente foram avaliados o número de microrganismos mesófilos em cada superfície e produto, bem como o número de estafilococos coagulase negativos e BAL. Em geral as superfícies apresentavam-se higienizadas, no entanto algumas mostraram níveis baixos de contaminação com L. monocytogenes e E. coli. Não foi detetada qualquer contaminação com Salmonella spp. nos diversos produtos analisados, independentemente do estado de cura, mas foram encontrados diferentes níveis de contaminação com L. monocytogenes e E. coli. O número de BAL é geralmente superior ao de estafilococos coagulase negativos. Agradecimentos Este trabalho foi financiado por Fundos FEDER através do Programa Operacional Factores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projeto PTDC/AGR-ALI/119075/2010 e dos Projetos Estratégicos PEst-C/AGR/UI0115/2011 e PEst-OE/AGR/UI0115/2014. Os autores agradecem à empresa PALADARES ALENTEJANOS, Lda. a colaboração prestada no âmbito do projeto PRODER 13.021 (QREN/PRODER/Medida 4.1)

    Improving thermoelectric properties of Ca 3 Co 4 O 9+d through both Na doping and K addition at optimal values

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    Ca 2.93 Na 0.07 Co 4 O y /x wt% K 2 CO 3 (x = 0.00, 0.01, and 0.03) polycrystalline ceramics were prepared by conventional solid-state method. XRD results have shown that all samples predominantly include Ca 3 Co 4 O 9 phase together with small amounts of secondary phases. SEM images show that all samples have randomly oriented plate-like grains in different sizes. The electrical resistivity measurement showed that electrical properties of Ca 3 Co 4 O 9 ceramics can be improved significantly by both, Na doping and K addition at their optimal values. The effect of dopants on thermoelectric properties of Ca 3 Co 4 O 9 was examined by both, Seebeck coefficient and power factor, being higher in K-added than in the pure samples, indicating that thermoelectric properties of samples are positively affected when alkaline elements enter into their structure

    Diploptene δ13C values from contemporary thermokarst lake sediments show complex spatial variation

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    Cryospheric changes in northern high latitudes are linked to significant greenhouse gas flux to the atmosphere, for example, methane that originates from organic matter decomposition in thermokarst lakes. The set of pathways that link methane production in sediments, via oxidation in the lake system, to the flux of residual methane to the atmosphere is complex and exhibits temporal and spatial variation. The isotopic signal of bacterial biomarkers (hopanoids, e.g. diploptene) in sediments has been used to identify contemporary ocean-floor methane seeps and, in the geological record, periods of enhanced methane production (e.g. the PETM). The biomarker approach could potentially be used to assess temporal changes in lake emissions through the Holocene via the sedimentary biomarker record. However, there are no data on the consistency of the signal of isotopic depletion in relation to source or on the amount of noise (unexplained variation) in biomarker values from modern lake sediments. We assessed methane oxidation as represented by the isotopic signal of biomarkers from methane oxidising bacteria (MOB) in multiple surface sediment samples in three distinct areas known to emit varying levels of methane in two shallow Alaskan thermokarst lakes. Diploptene was present and had δ13C values lower than -38g‰ in all sediments analysed, suggesting methane oxidation was widespread. However, there was considerable variation in δ13C values within each area. The most 13C-depleted diploptene was found in an area of high methane ebullition in Ace Lake (diploptene δ13C values between -68.2 and -50.1‰). In contrast, significantly higher diploptene δ13C values (between -42.9 and -38.8g‰) were found in an area of methane ebullition in Smith Lake. δ13C values of diploptene between -56.8 and -46.9g‰ were found in the centre of Smith Lake, where ebullition rates are low but diffusive methane efflux occurs. The small-scale heterogeneity of the samples may reflect patchy distribution of substrate and/or MOB within the sediments. The two ebullition areas differ in age and type of organic carbon substrate, which may affect methane production, transport, and subsequent oxidation. Given the high amount of variation in surface samples, a more extensive calibration of modern sediment properties, within and among lakes, is required before down-core records of hopanoid isotopic signatures are developed. © Author(s) 2016

    Nivel de proteína C reactiva en pacientes con obesidad mórbida antes y después de cirugía bariátrica

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    ResumenAntecedentesLa obesidad humana se asocia a un estado proinflamatorio reflejado en elevación de marcadores como la proteína C reactiva (PCR).ObjetivosEstablecer los valores de PCR basales y a 6 meses de la cirugía bariátrica, así como los cambios en peso, índice de masa corporal (IMC), leucocitos y glucemia.Materiales y métodosSe realizó un estudio observacional, analítico, retrospectivo, longitudinal y abierto. Se midieron los valores de PCR sérica y su relación con el peso, IMC, leucocitos y glucemia de manera basal y 6 meses posteriores a cirugía bariátrica en 36 adultos con obesidad mórbida.ResultadosLa media ± desviación estándar de la PCR pre y posoperatorio (mg/l) fue 1.15±0.86 y 0.34±0.28, respectivamente, con p<0.0001; peso (kg) 112.10±22.91 y 84.82±17.11, p=0,0443; IMC (kg/m2) 42.48±5.97 y 32.2±4.79, p=0.0988; glucosa (mg/dl) 100.58±17.82 y 87.11±8.49, p<0.0001, y leucocitos (× 103/mm3) 8.62±1.69 y 6.99±1.56, p=0.3192.La PCR basal solo correlacionó con el peso e IMC (p=0.047 y p=0.027, respectivamente) y no hubo correlación entre la PCR posoperatoria y ninguno de los parámetros evaluados.ConclusionesLa PCR tiene una relación lineal significativa en el preoperatorio con el peso y el IMC. Los pacientes sometidos a cirugía bariátrica presentaron disminución significativa en la PCR, el peso y la glucemia en ayuno a los 6 meses posterior a la cirugía.AbstractBackgroundHuman obesity is associated with a proinflammatory state and an elevated level of mediators, such as C-reactive protein (CRP).ObjectivesTo establish CRP levels as baseline preoperative values and then at 6 months after bariatric surgery, as well as to determine the changes in weight, body mass index (BMI), leukocytes, and glycemia.Materials and methodsAn observational, analytical, retrospective, longitudinal, and open study was conducted. Serum CRP values were measured in 36 adults presenting with morbid obesity, and their baseline relation to weight, BMI, leukocytes, and glycemia was determined; the relation to the same parameters was established again, 6 months after bariatric surgery.ResultsThe mean and standard deviation of preoperative and postoperative CRP (mg/L) was 1.15±0.86 and 0.34±0.28, respectively with p<0.0001; weight (kg) 112.10±22.91 and 84.82±17.11, p=0.0443; BMI (kg/m2) 42.48±5.97 and 32.2±4.79, p=0.0988; glucose (mg/dL) 100.58±17.82 and 87.11±8.49, p<0.0001, and leukocytes (× 103/mm3) 8.62±1.69 and 6.99±1.56, p=0.3192.Baseline CRP only correlated with weight and BMI (p=0.047 and p=0.027 respectively) and there was no correlation between postoperative CRP and the evaluated parameters.ConclusionsPreoperative CRP had a significant lineal relation to weight and body mass index. Patients who underwent bariatric surgery had a significant decrease in CRP, weight, and fasting glucose at 6 months after surgery

    Disability and its influence in nutritional assessment tools in elderly people living in nursing homes

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    Introduction: Poor nutritional status is associated with increased morbidity and mortality, especially in older people. Objective: The aim of this study was to assess nutritional status in elderly nursing home residents with different nutritional test, and to determine which parameters used for nutritional assessment can be carried out in this population, which usually have a high prevalence of functionally dependent residents. Methods: A cross-sectional study was performed in 383 elderly. The nutritional assessment tools used were the Mini Nutritional Assessment (MNA), the new ESPEN consensus definition of malnutrition, and the tool for Controlling Nutritional Status (CONUT). Moreover, the ability to perform basic activities of daily living was assessed with the Barthel index (BI). Results: According to BI, 78.9% had a total dependence and only 20.9% could be weighed and heighed. The prevalence of malnutrition with MNA, ESPEN and CONUT was 21.3%, 17.6% and 20.7%, respectively. The agreement between MNA vs ESPEN criteria was moderate (?= 0.483), but with CONUT was low. Conclusions: Nursing homes had a high percentage of totally dependent residents. This high degree of functional dependence made difficult to obtain some anthropometric parameters such as weight and height, which are essential to carry out most nutritional tests. MNA, CONUT and the new ESPEN criteria of malnutrition showed a high prevalence of malnutrition and risk of malnutrition in subjects in which they could be performed. Introducción: un estado nutricional deficiente está asociado con un incremento de la morbilidad y la mortalidad, especialmente en personas ancianas. Objetivo: el objetivo de este estudio fue evaluar el estado nutricional en ancianos institucionalizados en residencias geriátricas mediante diferentes test nutricionales, y determinar qué parámetros utilizados en la valoración nutricional pueden ser realizados en esta población. Métodos: se llevó a cabo un estudio transversal en 383 ancianos. Las herramientas de valoración nutricional empleadas fueron el Mini Nutritional Assessment (MNA), el nuevo consenso de definición de malnutrición, y el CONUT. Además, la capacidad de realizar las actividades básicas de la vida diaria fue evaluada con el índice de Barthel. Resultados: según el índice de Barthel, hasta un 78, 9% de los residentes tenía una dependencia total, y en solo el 20, 9% se pudo determinar el peso y la talla. La prevalencia de malnutrición con MNA, el consenso de ESPEN y CONUT fueron 21, 3%, 17, 2% y 20, 7%, respectivamente. La concordancia (kappa) entre el MNA y el ESPEN fue moderada (? = 0, 483), pero con CONUT fue baja. Conclusiones: en las residencias geriátricas públicas existe un elevado porcentaje de ancianos totalmente dependientes. Este alto grado de dependencia funcional dificulta la obtención de algunos parámetros antropométricos como el peso y la talla, que son esenciales para llevar a cabo la mayoría de los test de valoración nutricional. El MNA, el CONUT y los nuevos criterios de desnutrición de la ESPEN mostraron una elevada prevalencia de desnutrición y de riesgo de desnutrición en esta población de ancianos institucionalizados, en aquellos en los que fue posible realizarlos
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