1,056 research outputs found

    The formation and disintegration of magnetic bright points observed by Sunrise/IMaX

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    The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First we concentrate on the detailed description of the magnetic field evolution of three MBPs. This reveals that individual features follow different, generally complex, and rather dynamic scenarios of evolution. Next we apply statistical methods on roughly 200 observed MBP evolutionary tracks. MBPs are found to be formed by the strengthening of an equipartition field patch, which initially exhibits a moderate downflow. During the evolution, strong downdrafts with an average velocity of 2.4 km/s set in. These flows, taken together with the concurrent strengthening of the field, suggest that we are witnessing the occurrence of convective collapses in these features, although only 30% of them reach kG field strengths. This fraction might turn out to be larger when the new 4 m class solar telescopes are operational as observations of MBPs with current state of the art instrumentation could still be suffering from resolution limitations. Finally, when the bright point disappears (although the magnetic field often continues to exist) the magnetic field strength has dropped to the equipartition level and is generally somewhat weaker than at the beginning of the MBP's evolution. Noteworthy is that in about 10% of the cases we observe in the vicinity of the downflows small-scale strong (exceeding 2 km/s) intergranular upflows related spatially and temporally to these downflows.Comment: 19 pages, 13 figures; final version published in "The Astrophysical Journal

    Intermittent hypoxic training and cycling performance in triathletes

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    Los deportistas incorporan como complemento a su entrenamiento convencional, programas de entrenamiento en altitud para incrementar el rendimiento. El objetivo del estudio fue analizar los efectos sobre el umbral anaeróbico (Uan) producidos por un programa de entrenamiento en hipoxia intermitente (IHT) en triatletas. Participaron 18 triatletas divididos en un grupo de entrenamiento en hipoxia (GIHT: n=9; Edad: 26 ± 6.73 años; Talla 173.33 ± 5.94 cm; Peso: 66.38 ± 5.91 kg) y un grupo control (GC: n=9; Edad: 29.27 ± 6.84 años; Talla 174.89 ± 4.59 cm; Peso: 71.59 ± 6.81 Kg). Se aplicó un programa de IHT, complementario al entrenamiento habitual de 7 semanas al 15-14.5% de FiO2, 2 sesiones semanales de 60 minutos en cicloergómetro a la intensidad del Uan. Se llevó a cabo un test de umbrales lácticos previo y otro posterior al programa. El tratamiento propuesto produce un incremento en la potencia y el esfuerzo percibido en el Uan y disminuye la frecuencia cardiaca en el umbral aeróbico (Uae) y el UanAthletes include altitude training as a complement to their conventional training to improve performance. The aim of the study was to analyze the effects on anaerobic threshold (AT) produced by an IHT program in triathletes. 18 male trained triathletes were divided into intermittent hypoxic training group (GIHT: n=9; age: 26±6.73 years, height 173.33±5.94 cm, weight: 66.38±5.91 kg) and control group (GC: n=9; age: 29.27±6.84 years, height 174.89±4.59 cm, weight: 71.59±6.81 kg). The IHT program consisted of two 60-min sessions per week at intensities over the AT and atmospheric conditions between 14.5 and 15% FiO2. Before and after the program, cycling performance in a lactate thresholds test was determined. The treatment caused an improvement in the power output and perceived exertion in AT and enhanced cardiac performance in the aerobic threshold and AT

    Temporal evolution of the Evershed flow in sunspots. II. Physical properties and nature of Evershed clouds

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    Context: Evershed clouds (ECs) represent the most conspicuous variation of the Evershed flow in sunspot penumbrae. Aims: We determine the physical properties of ECs from high spatial and temporal resolution spectropolarimetric measurements. Methods: The Stokes profiles of four visible and three infrared spectral lines are subject to inversions based on simple one-component models as well as more sophisticated realizations of penumbral flux tubes embedded in a static ambient field (uncombed models). Results: According to the one-component inversions, the EC phenomenon can be understood as a perturbation of the magnetic and dynamic configuration of the penumbral filaments along which these structures move. The uncombed inversions, on the other hand, suggest that ECs are the result of enhancements in the visibility of penumbral flux tubes. We conjecture that the enhancements are caused by a perturbation of the thermodynamic properties of the tubes, rather than by changes in the vector magnetic field. The feasibility of this mechanism is investigated performing numerical experiments of thick penumbral tubes in mechanical equilibrium with a background field. Conclusions: While the one-component inversions confirm many of the properties indicated by a simple line parameter analysis (Paper I of this series), we tend to give more credit to the results of the uncombed inversions because they take into account, at least in an approximate manner, the fine structure of the penumbra.Comment: Accepted for publication in A&

    Protective role of mindfulness, self-compassion and psychological flexibility on the burnout subtypes among psychology and nursing undergraduate students

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    Aims: To explore the relationship between mindfulness, self-compassion and psychological flexibility, and the burnout subtypes in university students of the Psychology and Nursing degrees, and to analyse possible risk factors for developing burnout among socio-demographic and studies-related characteristics. Design: Cross-sectional study conducted on a sample of 644 undergraduate students of Nursing and Psychology from two Spanish universities. Methods: The study was conducted between December 2015 and May 2016. Bivariate Pearson''s correlations were computed to analyse the association between mindfulness facets, self-compassion and psychological flexibility, and levels of burnout. Multivariate linear regression models and bivariate and multivariate binary logistic regressions were also computed. Results: The three subtypes of burnout presented significant correlations with psychological flexibility, self-compassion and some mindfulness facets. Psychological flexibility, self-compassion and the mindfulness facets of observing and acting with awareness were significantly associated to burnout. Among the risk factors, ‘year of study’ was the only variable to show significantly higher risk for every burnout subtype. Conclusion: The significant associations found between mindfulness, self-compassion, psychological flexibility and burnout levels underline the need of including these variables as therapeutic targets when addressing the burnout syndrome in university students. Impact. Undergraduate students, especially those of health sciences, often experience burnout. This study delves into the protective role of some psychological variables: mindfulness, self-compassion and psychological flexibility. These should be considered as potentially protective skills for developing burnout, and therefore, undergraduate students could be trained on these abilities to face their studies and their future profession to prevent experiencing burnout syndrome. © 2021 John Wiley & Sons Lt

    Models and Observations of Sunspot Penumbrae

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    The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution. To help explaining these new observations I propose some modifications to each of them. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.Comment: 9 pages, 1 color figure. Review talk to appear in the proceedings of the International Workshop of 2008 Solar Total Eclipse: Solar Magnetism, Corona and Space Weather--Chinese Space Solar Telescope Scienc

    Programa de mentoría en la Facultad de Ciencias de la Universidad de Alicante

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    Un programa de mentoría es un proceso a través del cual, una persona con mayores conocimientos y experiencia en un determinado campo (el mentor) enseña, aconseja, guía y ayuda a otra (el mentorizado) en el aprendizaje, desarrollo de habilidades y mejora de actitudes relacionadas con dicho campo. El programa de mentoría que desarrollan la mayoría de universidades españolas es un programa educativo que trata de favorecer a los estudiantes de nuevo ingreso (mentorizados) su adaptación al entorno universitario, facilitando su integración social, académica y administrativa. Dicha labor es realizada por estudiantes de últimos cursos (mentores). Dado que la Universidad de Alicante ofrece el Programa de Acción Tutorial que cubre el aspecto de integración de los alumnos en la vida universitaria así como en el contexto curricular de los estudios que comienzan, el programa de mentoría que por segundo año ha llevado a cabo la Facultad de Ciencias de la Universidad de Alicante de manera global se ha dirigido exclusivamente a mejorar el rendimiento en las asignaturas de Matemáticas en las titulaciones de Biología, Ciencias del Mar, Geología, Química y Óptica y Optometría, donde los mentores han sido alumnos del último curso de la Licenciatura en Matemáticas. Con él se pretendía proporcionar una ayuda a los estudiantes de nuevo ingreso de las titulaciones mencionadas para que alcanzaran conceptos y niveles básicos necesarios para afrontar con éxito dichas asignaturas y disminuir los niveles de abandono actuales. En el presente trabajo se relata esta experiencia

    Changes in Biomarkers of Redox Status in Saliva of Pigs after an Experimental Sepsis Induction

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    Saliva from pigs is gaining attention as an easy sample to obtain, being a source of biomarkers that can provide information on animal health and welfare. This study aimed to evaluate the changes that can occur in salivary biomarkers of the redox status of pigs with an experimentally induced sepsis. For that, the cupric reducing antioxidant capacity (CUPRAC), ferric reducing ability of saliva (FRAS), Trolox equivalent antioxidant capacity (TEAC), advanced oxidation protein products (AOPP), ferrous oxidation-xylenol orange (FOX), peroxide activity (POX-Act), and reactive oxygen-derived compounds (d-ROMs) were measured in the saliva of pigs with experimentally induced sepsis by endotoxin lipopolysaccharide (LPS), non-septic inflammation induced by turpentine, and in healthy individuals before and after 3 h, 6 h, 24 h, and 48 h. AOPP, POX-Act, and d-ROMs in the sepsis group were higher than in the control from 3 h to 24 h after the inoculation. CUPRAC, FRAS, and TEAC were higher in sepsis than the control group at 24 h. These changes were of higher magnitude than those that occurred in the turpentine group. In conclusion, our findings reveal that sepsis produces changes in salivary biomarkers of redox status, which opens the possibility of using them as potential biomarkers in this species

    Genetic epidemiology of the Charcot-Marie-Tooth in the Spanish Gypsy population: the Hereditary Motor and Sensory Neuropathy type Russe in depth

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    [EN] Four private mutations responsible for three forms demyelinating of Charcot-Marie-Tooth (CMT) or hereditary motor and sensory neuropathy (HMSN) have been associated with the Gypsy population: the NDRG1 p.R148X in CMT type 4D (CMT4D/HMSN-Lom); p.C737_P738delinsX and p.R1109X mutations in the SH3TC2 gene (CMT4C); and a G>C change in a novel alternative untranslated exon in the HK1 gene causative of CMT4G (CMT4G/HMSN-Russe). Here we address the findings of a genetic study of 29 Gypsy Spanish families with autosomal recessive demyelinating CMT. The most frequent form is CMT4C (57.14%), followed by HMSN-Russe (25%) and HMSN-Lom (17.86%). The relevant frequency of HMSN-Russe has allowed us to investigate in depth the genetics and the associated clinical symptoms of this CMT form. HMSN-Russe probands share the same haplotype confirming that the HK1 g.9712G>C is a founder mutation, which arrived in Spain around the end of the 18th century. The clinical picture of HMSN-Russe is a progressive CMT disorder leading to severe weakness of the lower limbs and prominent distal sensory loss. Motor nerve conduction velocity was in the demyelinating or intermediate range.We thank all patients and their relatives for their kind collaboration. We also thank Drs G. Glover, R. Vilches, F. Galan, and C. Diaz for referring patients for genetic analysis. We also acknowledge F Barraclough for English corrections. This work was supported by the Instituto de Salud Carlos III (ISCIII) (grants number PI08/90857, PI08/0889, CP08/00053 and PS09/00095) co-funded with FEDER funds and by the ISCIII-IRDiRC Programme (TREAT-CMT grant). C. E. has a 'Miguel Servet' contract funded by the ISCIII. Both Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER) and Centro de Investigacion Biomedica en Red de Enfermedades Neurodegenerativas (CIBERNED) are initiative from the ISCIII.Sevilla, T.; Martínez-Rubio, D.; Márquez, C.; Paradas, C.; Colomer, J.; Jaijo, T.; Millán, J.... (2013). Genetic epidemiology of the Charcot-Marie-Tooth in the Spanish Gypsy population: the Hereditary Motor and Sensory Neuropathy type Russe in depth. Clinical Genetics. 83(6):565-570. https://doi.org/10.1111/cge.1201556557083

    Isokinetic leg strength and power in elite handball players

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    Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.Actividad Física y Deport
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