154 research outputs found

    Big rip avoidance via black holes production

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    We consider a cosmological scenario in which the expansion of the Universe is dominated by phantom dark energy and black holes which condense out of the latter component. The mass of black holes decreases via Hawking evaporation and by accretion of phantom fluid but new black holes arise continuously whence the overall evolution can be rather complex. We study the corresponding dynamical system to unravel this evolution and single out scenarios where the big rip singularity does not occur.Comment: 16 pages, two figures. Key words. Cosmology, phantom energy, black holes. Sligthly extended version to be published in Gravitation and Cosmolog

    Physical activity, fitness and adiposity: immigrants versus spanish scholars

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    El objetivo fue analizar las asociaciones entre los niveles de condición física, patrones de actividad física y adiposidad del alumnado nativo e inmigrante. Se estudiaron 612 niños (8-10 años) de colegios públicos, valorándose mediante pruebas antropométricas, condición física y cuestionario de hábitos de actividad física. Se observó que el alumnado que realizaba mayor actividad física presentaba menor índice de masa corporal y mayor condición física. El alumnado inmigrante presentó menor adiposidad y mayor participación en actividades deportivas. No encontramos diferencias en condición física, salvo en chicas inmigrantes, con mayor fuerza del tren inferior. En conclusión, los inmigrantes del presente estudio parecen poseer un perfil más saludable de condición física, actividad física y adiposidad que los nativos.The objective was to analyse the associations of physical fitness and patterns of physical activity with adiposity in native and foreign. This study was performed with 612 school students (8-10 years). Anthropometric measurements, physical fitness and activity patterns were studied. The results showed that students who practiced more physical activity had lower body mass index and higher levels of fitness. Immigrants had lower adiposity and higher participation in sport activities than native students. No differences between native and foreing students in levels were found, except for immigrant girls, who showed greater lower body strengh than the natives ones. In conclusion, immigrants from this study appear to have a healthier fitness, physical activity and adiposity than natives.Este estudio ha sido financiando por la de la Dirección General de Participación e Innovación Educativa, por la que se aprueban proyectos de investigación e innovación educativa y de elaboración de materiales curriculares de de la Consejería de Educación de Andalucía. RESOLUCIÓN de 14 de julio de 2010 (PIV-038/10), y con una beca del Ministerio de Ciencia e Investigación (JCI-2010-07055)

    Association of objectively measured physical activity with body components in European adolescents

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    Background: Physical activity (PA) is suggested to contribute to fat loss not only through increasing energy expenditure “per se” but also increasing muscle mass; therefore, it would be interesting to better understand the specific associations of PA with the different body’s components such as fat mass and muscle mass. The aim of the present study was to examine the association between objectively measured PA and indices of fat mass and muscle components independently of each other giving, at the same time, gender-specific information in a wide cohort of European adolescents. Methods: A cross-sectional study in a school setting was conducted in 2200 (1016 males) adolescents (14.7 ±1.2 years). Weight, height, skinfold thickness, bioimpedance and PA (accelerometry) were measured. Indices of fat mass (body mass index, % fat mass, sum of skinfolds) and muscular component (assessed as fat-free mass) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat-free mass and fat mass when possible. Results: Vigorous PA was positively associated with height (p?<?0.05) in males, whilst, vigorous PA, moderate-vigorous PA and average PA were negatively associated with all the indices of fat mass (all p?<?0.01) in both genders, except for average PA in relation with body mass index in females. Regarding muscular components, vigorous PA showed positive associations with fat-free mass and muscle mass (all p?<?0.05) in both genders. Average PA was positively associated with fat-free mass (both p?<?0.05) in males and females. Conclusion: The present study suggests that PA, especially vigorous PA, is negatively associated with indices of fat mass and positively associated with markers of muscle mass, after adjusting for several confounders (including indices of fat mass and muscle mass when possible). Future studies should focus not only on the classical relationship between PA and fat mass, but also on PA and muscular components, analyzing the independent role of both with the different PA intensities

    Impact of an intermittent and localized cooling intervention on skin temperature, sleep quality and energy expenditure in free-living, young, healthy adults

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    Where people live and work together it is not always possible to modify the ambient temperature; ways must therefore be found that allow individuals to feel thermally comfortable in such settings. The Embr Wave (R) is a wrist-worn device marketed as a 'personal thermostat' that can apply a local cooling stimulus to the skin. The aim of the present study was to determine the effect of an intermittent mild cold stimulus of 25 degrees C for 15-20 s every 5 min over 3.5 days under free-living conditions on 1) skin temperature, 2) perception of skin temperature, 3) sleep quality and 4) resting energy expenditure (REE) in young, healthy adults. Ten subjects wore the device for 3.5 consecutive days. This intervention reduced distal skin temperature after correcting for personal ambient temperature (P = 0.051). Thus, this intermittent mild cold regime can reduce distal skin temperature, and wearing it under free-living conditions for 3.5 days does not seem to impair the perception of skin temperature and sleep quality or modify REE.The study was funded by the Spanish Ministry of Economy and Competitiveness via the Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III (PI13/01393 and CB16/10/00239) and PTA 12264-I, Retos de la Sociedad (DEP2016-79512-R), and European Regional Development Funds (ERDF). Other funders included the Spanish Ministry of Education (FPU 16/05159, 15/04059 and 19/02326), the Fundacion Iberoamericana de Nutricion (FINUT), the Redes Tematicas De Investigacion Cooperativa RETIC (Red SAMID RD16/0022), the AstraZeneca Health Care Foundation, the University of Granada Plan Propio de Investigacion 2016 (Excellence actions: Unit of Excellence on Exercise, Nutrition and Health [UCEENS]), and by the Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades (ERDF, SOMM17/6107/UGR). AMT was supported by Seneca Foundation through grant 19899/GERM/15 and the Ministry of Science Innovation and Universities RTI2018-093528-B-I0, as well as DJP (MINECO; RYC-2014-16938). BMT was supported by an individual postdoctoral grant from the Fundacion Alfonso Martin Escudero. We thank Dr. Matt Smith of Embr Labs Inc. for configuring the Embr Wave (R) devices used in this experiment

    Association of body composition indices with insulin resistance in European adolescents: The HELENA study

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    Background: The different body components may contribute to the development of insulin resistance and type 2 diabetes mellitus. The aim of the present study was to examine the association of fat mass and fat free mass indices with markers of insulin resistance, independently of each other and giving, at the same time, gender-specific information in a wide cohort of European adolescents. Methods: A cross-sectional study in a school setting was conducted in 925 (430 males) adolescents (14.9 ± 1.2 years). Weight, height, anthropometric, bioimpedance and blood parameters were measured. Indices for fat mass and fat free mass, and homeostatic model assessment (HOMA) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat free mass and fat mass when possible. Results: Indices of fat mass were positively associated with HOMA (all p < 0.01) after adjusting for all the confounders including fat free mass indices, in both sexes. Fat free mass indices were associated with HOMA, in both males and females, after adjusting for center, pubertal status, socioeconomic status and cardiorespiratory fitness, but the associations disappear when including fat mass indices in the adjustment’s model. Conclusion: Fat mass indices derived from different methods are positively associated with insulin resistance independently of several confounders including fat free mass indices. In addition, the relationship of fat free mass with insulin resistance is influenced by the amount of fat mass in European adolescents. Nevertheless, future studies should focus not only on the role of fat mass, but also on other body components such as fat free mass because its role could vary depending of the level and distribution of fat mass

    Independent and combined influence of healthy lifestyle factors on academic performance in adolescents: DADOS Study

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    BACKGROUND. Few studies have analyzed the combined effect of lifestyle factors on academic performance (AP) in adolescents. The aim of this study was to analyze the independent and combined effects of weight status, screen time, sleep quality, daily meal frequency, cardiorespiratory fitness and physical activity (PA) on AP in adolescents. METHODS. A total of 262 adolescents (13.9±0.3 years) from the DADOS study were included in the analysis. Weight status was assessed through body mass index (kg/m 2 ). Participants completed questionnaires to evaluate screen time, sleep quality and daily meal frequency. Cardiorespiratory fitness was assessed by the 20-m shuttle run test. PA was evaluated by a wrist-worn GENEActiv accelerometer. AP was assessed through the final academic grades and a validated questionnaire. RESULTS. Non-overweight status, low screen time, good sleep quality and proper meal frequency showed independent, positive influence on AP. Moreover, adolescents achieving at least 3 healthy lifestyles were more likely to be in the high-performance group for academic grades than those achieving ≤ 1 (math OR: 3.02-9.51, language OR: 3.51-6.76 and grade point average OR: 4.22-9.36). CONCLUSIONS. Although individual healthy lifestyles are independently and positively associated with AP, the cumulative effect of multiple healthy lifestyles have a stronger impact

    Physical activity and clustered cardiovascular disease risk factors in young children: a cross-sectional study (the IDEFICS study)

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    &lt;p&gt;Background The relevance of physical activity (PA) for combating cardiovascular disease (CVD) risk in children has been highlighted, but to date there has been no large-scale study analyzing that association in children aged &#8804;9 years of age. This study sought to evaluate the associations between objectively-measured PA and clustered CVD risk factors in a large sample of European children, and to provide evidence for gender-specific recommendations of PA.&lt;/p&gt; &lt;p&gt;Methods Cross-sectional data from a longitudinal study in 16,224 children aged 2 to 9 were collected. Of these, 3,120 (1,016 between 2 to 6 years, 2,104 between 6 to 9 years) had sufficient data for inclusion in the current analyses. Two different age-specific and gender-specific clustered CVD risk scores associated with PA were determined. First, a CVD risk factor (CRF) continuous score was computed using the following variables: systolic blood pressure (SBP), total triglycerides (TG), total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-c) ratio, homeostasis model assessment of insulin resistance (HOMA-IR), and sum of two skinfolds (score CRFs). Secondly, another CVD risk score was obtained for older children containing the score CRFs + the cardiorespiratory fitness variable (termed score CRFs + fit). Data used in the current analysis were derived from the IDEFICS (‘Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS’) study.&lt;/p&gt; &lt;p&gt;Results In boys &#60;6 years, the odds ratios (OR) for CVD risk were elevated in the least active quintile of PA (OR: 2.58) compared with the most active quintile as well as the second quintile for vigorous PA (OR: 2.91). Compared with the most active quintile, older children in the first, second and third quintiles had OR for CVD risk score CRFs + fit ranging from OR 2.69 to 5.40 in boys, and from OR 2.85 to 7.05 in girls.&lt;/p&gt; &lt;p&gt;Conclusions PA is important to protect against clustering of CVD risk factors in young children, being more consistent in those older than 6 years. Healthcare professionals should recommend around 60 and 85 min/day of moderate-to-vigorous PA, including 20 min/day of vigorous PA.&lt;/p&gt

    Integration of the archaeological Almohad remains in Granada metro station. The multidisciplinary research for the project and contemporary infrastructure development in the historic centres

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    La ejecución del tramo subterráneo del metropolitano de Granada ha permitido el hallazgo de los restos arqueológicos de la alberca del Alcázar Genil, residencia regia musulmana periurbana del siglo XIII. El Albercón, de 128 × 27 metros, fue devorado en sus extremos durante el crecimiento urbano del siglo XX, salvándose el tramo central pisado por el Camino de Ronda, vial bajo cuyo trazado discurre el metropolitano. El emplazamiento en Alcázar Genil de una estación subterránea posibilitará la integración de los restos arqueológicos de la alberca, recuperándolos, poniéndolos en valor y haciéndolos visitables.El proyecto de la estación Alcázar Genil aúna los esfuerzos conjuntos de diversas disciplinas que ponen al mismo nivel las ingenierías de los siglos XIII y XXI con una visión interdisciplinar básica para abarcar la complejidad de todo el proyecto con el objetivo de compatibilizar las infraestructuras contemporáneas con el pasado oculto bajo la piel de nuestros viejos centros históricos.The execution of the Granada Metropolitan’s underground line made possible the discovery of archeological remains of a water tank in Alcázar Genil, a royal muslim residence of the 13th century. The water tank, 419 × 88 ft, was destroyed at its ends due to the growth of the city of Granada during the 20th century and today remains only its center section, under Camino de Ronda, exactly where the future Metropolitan will take place. The location of an underground station will allow the recovery, the integration and the exhibition of the archaeological remains of this water tank. The Alcázar Genil station project brings together the work of several disciplines which put in the same level engineering of the 13th and of the 20th century. These different teams work in an interdisciplinary approach to respond to the complexity of the entire project. The aim is to make contemporary infrastructures compatible with the past that is hidden under the skin of our historic centres
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