4,126 research outputs found

    The onset of solar cycle 24: What global acoustic modes are telling us

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    We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF instrument are analyzed. A multi-step iterative maximum-likelihood fitting method is applied to subseries of 365 days and 91.25 days to extract the p-mode parameters. Temporal variations of the l=0, 1, and 2 p-mode frequencies are then obtained from April 1996 to May 2009. While the p-mode frequency shifts are closely correlated with solar surface activity proxies during the past solar cycles, the frequency shifts of the l=0 and l=2 modes show an increase from the second half of 2007, when no significant surface activity is observable. On the other hand, the l=1 modes follow the general decreasing trend of the solar surface activity. The different behaviours between the l=0 and l=2 modes and the l=1 modes can be interpreted as different geometrical responses to the spatial distribution of the solar magnetic field beneath the surface of the Sun. The analysis of the low-degree, solar p-mode frequency shifts indicates that the solar activity cycle 24 started late 2007, despite the absence of activity on the solar surface.Comment: To be accepted by A&A (with minor revisions), 4 pages, 3 figures, 1 tabl

    The acoustic cut-off frequency of the Sun and the solar magnetic activity cycle

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    The acoustic cut-off frequency -the highest frequency for acoustic solar eigenmodes- is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but traveling waves. Interference amongst them give rise to higher-frequency peaks -the pseudomodes- in the solar acoustic spectrum. The pseudomodes are shifted slightly in frequency with respect to p modes making possible the use of pseudomodes to determine the acoustic cut-off frequency. Using data from GOLF and VIRGO instruments on board the SOHO spacecraft, we calculate the acoustic cut-off frequency using the coherence function between both the velocity and intensity sets of data. By using data gathered by these instruments during the entire lifetime of the mission (1996 till the present), a variation in the acoustic cut-off frequency with the solar magnetic activity cycle is found.Comment: Paper accepted in ApJ. 26 Pages, 9 figure

    Pollen morphology of native and cultivated species of Handroanthus (Bignoniaceae) present in Argentina

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    Morfología polínica de las especies nativas y cultivadas de Handroanthus (Bignoniaceae) de la República Argentina. El objetivo del siguiente trabajo consiste en ampliar el conocimiento palinológico de las especies de Handroanthus (Bignoniaceae) presentes en Argentina e incorporar esta información al Atlas Polínico del NOA que se publica periódicamente on line (www.atlaspolinicodelnoa.com.ar). Se analizaron las siguientes especies: H. albus (Cham.) Mattos, H. chrysotrichus (Mart. ex DC.) Mattos, H. heptaphyllus (Vell.) Mattos, H. impetiginosus (Mart.ex DC.) Mattos, H. lapacho (K. Schum.) Mattos, H. ochraceus (Cham.) Mattos, además de la exótica H. pulcherrimus (Sandwith) S. Grose. El material fue procesado según las técnicas convencionales para acetólisis y polen natural, se tomaron fotos a nivel de microscopía óptica (MO) y microscopía electrónica de barrido (MEB). Los resultados muestran que los granos son medianos de 25 a 31,6 μm en polen natural y de 27,45 a 48 μm en polen acetolizado, suboblatos a subprolatos. Tricolporados (colporoidados) en H. albus, H. chrysotrichus, H. heptaphyllus, H. impetiginosus, H. lapacho y H. pulcherrimus, y 3-colporados (colporoidados), 3-hemisincolporados y loxocolporados en H. ochraceus. La exina es de 1,5 a 2 μm de espesor con la superficie reticulada heterobrocada

    Autologous and Allogeneic Stem Cell Transplantation for Treatment of Crohn’s Fistulae

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    Up to 20% of patients with Crohn’s disease (CD) may have perianal fistula disease. Classically, surgery has played an important role; in recent years, medical treatment has taken a leading role. Immunosuppressants and biological trea tments have proven beneficial in many patients, but still, the percentage of patients who do not respond remains significant. In this scenario, cell therapy is envisaged as an effective alternative to surgery. The promising preclinical and clinical data that we review below suggest that cell therapy could represent a major advance in the clinical management of this difficult problem

    Significado de la anemia en las diferentes etapas de la vida

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    Overview: Anemia is very common in primary care consultations and pediatrics, and IDA is the cause of 50% of all cases of anemia. Methodology: Literature review and documentary descriptive analysis of the pathogenesis of iron-deficiency anemia, the basic diagnostic tests to study IDA and the significance of such using a specific time period in the documentary search and inclusion criteria that takes into account factors that are analyzed in the study: Ideas about the metabolism of iron. Ideas about hematopoiesis. Laboratory diagnosis and classification of anemia. Clinical features of iron deficiency anemia. Causes of iron deficiency. Results and conclusion: The staged documentary study covers the publications on the pathogenesis of iron deficiency anemia, the basic diagnostic tests to study the IDA and the significance of such, and it shows how important this data is for professional nursing in the area of primary care and pediatrics, to identify it and act accordingly.Resumen: La anemia presenta una elevada prevalencia en las consultas de atención primaria y pediatría, y la ADH representa el 50% de todos los casos de anemia. Metodología: Revisión bibliográfica y análisis descriptivo documental sobre etiopatogenia de la anemia ferropénica, las pruebas diagnósticas básicas para el estudio de la ADH  y su significado, utilizando una temporalidad determinada en la búsqueda documental y criterios de inclusión atendiendo a las dimensiones que se analizan en el estudio: Nociones acerca del metabolismo del hierro. Nociones acerca de la hematopoyesis. Diagnóstico por el laboratorio y clasificación de las anemias. Clínica de la anemia ferropénica. Causas de la deficiencia de hierro. Resultados y conclusión: EL estudio documental efectuado nos presenta la existencia de publicaciones con contenidos sobre etiopatogenia de la anemia ferropénica, las pruebas diagnósticas básicas para el estudio de la ADH  y su significado, evidenciando la importancia de este contenido para el profesional de enfermería en el área de la atención primaria y pediatría

    Gendered medicinal plant knowledge contributions to adaptive capacity and health sovereignty in Amazonia

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    Local medical systems are key elements of social-ecological systems as they provide culturally appropriate and locally accessible health care options, especially for populations with scarce access to biomedicine. The adaptive capacity of local medical systems generally rests on two pillars: species diversity and a robust local knowledge system, both threatened by local and global environmental change. We first present a conceptual framework to guide the assessment of knowledge diversity and redundancy in local medicinal knowledge systems through a gender lens. Then, we apply this conceptual framework to our research on the local medicinal plant knowledge of the Tsimane’ Amerindians. Our results suggest that Tsimane’ medicinal plant knowledge is gendered and that the frequency of reported ailments and the redundancy of knowledge used to treat them are positively associated. We discuss the implications of knowledge diversity and redundancy for local knowledge systems’ adaptive capacity, resilience, and health sovereignty.Peer reviewe

    High overlap between traditional ecological knowledge and forest conservation found in the Bolivian Amazon

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    Unidad de excelencia María de Maeztu MdM-2015-0552Altres ajuts: FBBVA research grant (BIOCON_06_106-07)It has been suggested that traditional ecological knowledge (TEK) may play a key role in forest conservation. However, empirical studies assessing to what extent TEK is associated with forest conservation compared with other variables are rare. Furthermore, to our knowledge, the spatial overlap of TEK and forest conservation has not been evaluated at fine scales. In this paper, we address both issues through a case study with Tsimane' Amerindians in the Bolivian Amazon. We sampled 624 households across 59 villages to estimate TEK and used remote sensing data to assess forest conservation. We ran statistical and spatial analyses to evaluate whether TEK was associated and spatially overlapped with forest conservation at the village level. We find that Tsimane' TEK is significantly and positively associated with forest conservation although acculturation variables bear stronger and negative associations with forest conservation. We also find a very significant spatial overlap between levels of Tsimane' TEK and forest conservation. We discuss the potential reasons underpinning our results, which provide insights that may be useful for informing policies in the realms of development, conservation, and climate. We posit that the protection of indigenous cultural systems is vital and urgent to create more effective policies in such realms

    An infinite family of magnetized Morgan-Morgan relativistic thin disks

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    Applying the Horsk\'y-Mitskievitch conjecture to the empty space solutions of Morgan and Morgan due to the gravitational field of a finite disk, we have obtained the corresponding solutions of the Einstein-Maxwell equations. The resulting expressions are simply written in terms of oblate spheroidal coordinates and the solutions represent fields due to magnetized static thin disk of finite extension. Now, although the solutions are not asymptotically flat, the masses of the disks are finite and the energy-momentum tensor agrees with the energy conditions. Furthermore, the magnetic field and the circular velocity show an acceptable physical behavior.Comment: Submitted to IJTP. This paper is a revised and extended version of a paper that was presented at arXiv:1006.203
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