6,418 research outputs found

    Effects of the second virial coefficient on the adiabatic lapse rate of dry atmospheres

    Full text link
    We study the effect of the second virial coefficient on the adiabatic lapse rate of a dry atmosphere. To this end, we compute the corresponding adiabatic curves, the internal energy, and the heat capacity, among other thermodynamic parameters. We apply these results to Earth, Mars, Venus, Titan, and the exoplanet G1 851d, considering three physically relevant virial coefficients in each case: the hard-sphere, van der Waals, and the square-well potential. These examples illustrate under which atmospheric conditions the effect of the second virial coefficient is relevant. Taking the latter into account yields corrections towards the experimental values of the lapse rates of Venus and Titan in some instances.Comment: 12 pages, 8 figures. Comments are welcom

    Insuficiencia cardíaca congestiva en la clínica de pequeños animales. Terapéutica práctica moderna II. Inotropos positivos

    Get PDF
    En el presente trabajo revisamos los usos más frecuentes de los digitálicos, pautas de medicación y elección del producto, dosis, intervalos de dosis, formas comerciales y vías de administración más indicados para cada situación y completamos el tratamiento inotrópico con una revisión de catecolaminas sintéticas, bipiridinas y algunos fármacos potencialmente útiles en la práctica diaria.In this paper tbc autors review tbe more frecuents uses of the digitalis glycosides, dosages, how to choose thee best dtug, dosing intervals, comercial forms availablesin Spain and way of administration more indicated for each clinical situation, and we finish with a quick review of the sinthetic sympathomimetics amines and bipyridine compounds

    Physical activity practice and attitudes in canarian teenagers

    Full text link
    En el presente estudio de la población adolescente de la Comunidad Autónoma de Canarias, se evidencia que aquellos adolescentes que cumplen con las recomendaciones de práctica de Actividad Física tanto de intensidad moderada como vigorosa frente a los que no las cumplen, muestran a su vez mejores valores en la percepción del conjunto de actitudes que influyen en los niveles de práctica; competencia motriz, disfrute y valor-utilidad otorgada a la misma. Lo cual nos permite afirmar que este conjunto de factores pueden determinar el tipo y grado de participación en actividades físico-deportivas en este sector de la poblaciónIn this actual study of the adolescent population of the Autonomous Region of the Canary Islands, is evident, that teens who comply with the recommendations of practice of physical activity both of moderate intensity as vigorous intensity, compared with those which do not comply, show the best values in the perception of the set of attitudes that influence the levels of practice; perceived competence, enjoyment, perceived value. Which allows us to affirm that this set of factors can determine the type and degree of participation in physical-sport activities in this sector of the populatio

    Metodología para la evaluación de la sostenibilidad en autopistas: cálculo del balance energético de la infraestructura.

    Get PDF
    El trabajo aborda el desarrollo de un procedimiento para la evaluación de la eficiencia energética en infraestructuras lineales desde el punto de vista constructivo. El procedimiento permite calcular, tanto globalmente como de forma independizada, el balance energético de las diferentes fases del ciclo de vida de la infraestructura: construcción, operación y desmantelamiento o deconstrucción

    Efficacy of Neurofeedback on the Increase of Mindfulness-Related Capacities in Healthy Individuals: a Controlled Trial

    Get PDF
    Electroencephalogram (EEG) studies of mindfulness have shown it can lead to increases in alpha power, which are similar to those obtained by alpha-based neurofeedback (NF) interventions. It has been hypothesized there may be relationships between mindfulness and NF in terms of the neural pathways through which they induce salutary outcomes. The aim of the study was to evaluate possible changes in mindfulness and cognitive functioning following an alpha-based NF intervention, and the role of alpha power as a mediator of improvements. A controlled, non-randomized, trial with 50 healthy participants was conducted with two experimental conditions: a six-session NF intervention and a waiting-list control group. Both groups were administered mindfulness questionnaires (Mindful Attention Awareness Scale (MAAS), Five Facet Mindfulness Questionnaire (FFMQ)) and cognitive measures (Paced Auditory Serial Addition Task (PASAT)), at pre- and post-test. The NF intervention focused on the up-regulation of upper alpha power. Differences among groups were estimated using ANCOVAs, and mediation assessment through path analyses. Compared to controls, the NF group showed enhanced task-related upper alpha power (effect size (ES) = 1.16, p < 0.001), mindfulness outcomes (MAAS: ES = 0.94, p = 0.004; FFMQ: ES = 1.38, p < 0.001), and a trend of cognitive functioning (PASAT time: ES = 0.59, p = 0.062). Upper alpha power had a mediating effect for cognitive functioning (PASAT errors: indirect effect = 0.81, 95% CI = 0.21–1.85), but not for mindfulness. These results demonstrate the effectiveness of NF for increasing mindfulness in healthy individuals with no previous experience in mindfulness or neurofeedback training, suggesting that NF may be an acceptable method of augmenting mindfulness-related capacities in the general population

    Osteosarcoma perióstico: caso clínico

    Get PDF
    El osteosarcoma perióstico es un sarcoma raro que asienta en la superficie del hueso. Aunque algunos autores lo incluyen en los osteosarcomas yuxtacorticales sus peculiaridades clínicas, radiológicas y anatomopatológicas entre ellos que llevan a diferencias en el tratamiento y pronóstico le otorgan personalidad propia. Presentamos un caso clínico de osteosarcoma perióstico en un varón de 18 años, a nivel de fémur. Se realiza una revisión de la bibliografía, señalando las principales características de esta entidad.Periosteal osteosarcoma is a rare malignant neoplasm located on bone surface. Although some authors include it among juxtacortical osteosarcoma, its clinical feature, imaging studies findings and histologic patterns which lead to differences in the treatment and prognostic, give to it a peculiar identity. We report a case of an 18 years old man who had this tumour in his femur. We do a review of literature

    Aleatorizando el modelo de crecimiento malthusiano

    Full text link
    [EN] This paper deals with the randomization of the classical malthusian model using a markovian approach. We show that the solution stochastic process, usually referred to as birth process, corresponds to the shift negative binomial distribution. A simulation procedure is included. A brief discussion regarding alternative ways to consider randomness into the malthusian model are also included.[ES] Este trabajo ilustra, mediante el modelo de crecimiento clásico malthusiano, cómo introducir la aleatoriedad utilizando el enfoque markoviano. Se prueba que la función generatriz de probabilidad del proceso estocástico solución, denominado de nacimiento, es una distribución binomial negativa desplazada. Se detalla una técnica para simular el proceso estocástico solución. También se realiza una breve digresión acerca de otras formas posibles de introducir la incertidumbre en el modelo determinista malthusiano.Cortés, J.; García Moreno, E.; Navarro-Quiles, A. (2017). Aleatorizando el modelo de crecimiento malthusiano. Sociedad Puig Adam de profesores de matemáticas. 103:52-65. http://hdl.handle.net/10251/148893S526510

    Sustainability indicator for the prevention of potential thermal interferences between groundwater heat pump systems in urban aquifers

    Get PDF
    The steady increase of geothermal systems using groundwater is compromising the renewability of the geothermal resources in shallow urban aquifers. To ensure sustainability, scientifically-based criteria are required to prevent potential thermal interferences between geothermal systems. In this work, a management indicator (balanced sustainability index, BSI) applicable to groundwater heat pump systems is defined to assign a quantitative value of sustainability to each system, based on their intrinsic potential to produce thermal interference. The BSI indicator relies on the net heat balance transferred to the terrain throughout the year and the maximum seasonal thermal load associated. To define this indicator, 75 heating-cooling scenarios based in 23 real systems were established to cover all possible different operational conditions. The scenarios were simulated in a standard numerical model, adopted as a reference framework, and thermal impacts were evaluated. Two polynomial regression models were used for the interpolation of thermal impacts, thus allowing the direct calculation of the sustainability indicator developed as a function of heating-cooling ratios and maximum seasonal thermal loads. The BSI indicator could provide authorities and technicians with scientifically-based criteria to establish geothermal monitoring programs, which are critical to maintain the implementation rates and renewability of these systems in the cities

    White dwarfs with hydrogen-deficient atmospheres and the dark matter content of the Galaxy

    Get PDF
    The nature of the several microlensing events observed by the MACHO team towards the Large Magellanic Cloud (LMC) is still a subject of debate. Low-mass substellar objects and stars with masses larger than ~M_{sun} have been ruled out as major components of a Massive Astrophysical Compact Halo Object (MACHO) Galactic halo, while stars of half a solar mass seem to be viable candidates. Main sequence stars have been already discarded, and there are tight restrictions on the role played by white dwarfs with hydrogen-dominated atmospheres. In this paper we evaluate the contribution to the dark matter content of the Galaxy of white dwarfs with hydrogen-deficient atmospheres. For this purpose we use a Monte Carlo simulator which incorporates up-to-date evolutionary sequences of white dwarfs with hydrogen-rich and hydrogen-deficient atmospheres. We also take into account detailed descriptions of the thick disk and the halo of our Galaxy as well as of a reliable model of the LMC. We find that the contribution of white dwarfs with hydrogen-deficient atmospheres moderately increases the theoretical estimate of the optical depth with respect to the value obtained when only hydrogen-rich white dwarfs are considered. We also find that the contribuiton of the thick disk population of white dwarfs is comparable to the halo contribution. However, the contributions of both the halo and the thick disk white-dwarf populations are still insufficient to explain the number of events observed by the MACHO team. Finally, we find that the contribution to the halo dark matter of the entire population under study is less than 10% at the 95% conficence level.Comment: 12 pages, 5 figures, accepted for publication in A&

    MicroRNA-mediated differential expression of TRMU, GTPBP3 and MTO1 in cell models of mitochondrial-DNA diseases

    Get PDF
    Mitochondrial diseases due to mutations in the mitochondrial (mt) DNA are heterogeneous in clinical manifestations but usually include OXPHOS dysfunction. Mechanisms by which OXPHOS dysfunction contributes to the disease phenotype invoke, apart from cell energy deficit, maladaptive responses to mitochondria-to-nucleus retrograde signaling. Here we used five different cybrid models of mtDNA diseases to demonstrate that the expression of the nuclear-encoded mt-tRNA modification enzymes TRMU, GTPBP3 and MTO1 varies in response to specific pathological mtDNA mutations, thus altering the modification status of mt-tRNAs. Importantly, we demonstrated that the expression of TRMU, GTPBP3 and MTO1 is regulated by different miRNAs, which are induced by retrograde signals like ROS and Ca2+ via different pathways. Our data suggest that the up- or down-regulation of the mt-tRNA modification enzymes is part of a cellular response to cope with a stoichiometric imbalance between mtDNA- and nuclear-encoded OXPHOS subunits. However, this miRNA-mediated response fails to provide full protection from the OXPHOS dysfunction; rather, it appears to aggravate the phenotype since transfection of the mutant cybrids with miRNA antagonists improves the energetic state of the cells, which opens up options for new therapeutic approaches
    corecore