2,193 research outputs found

    Maximum likelihood estimation of regularisation parameters

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    Analysis of a long-duration AR throughout five solar rotations: Magnetic properties and ejective events

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    Coronal mass ejections (CMEs), which are among the most magnificent solar eruptions, are a major driver of space weather and can thus affect diverse human technologies. Different processes have been proposed to explain the initiation and release of CMEs from solar active regions (ARs), without reaching consensus on which is the predominant scenario, and thus rendering impossible to accurately predict when a CME is going to erupt from a given AR. To investigate AR magnetic properties that favor CMEs production, we employ multi-spacecraft data to analyze a long duration AR (NOAA 11089, 11100, 11106, 11112 and 11121) throughout its complete lifetime, spanning five Carrington rotations from July to November 2010. We use data from the Solar Dynamics Observatory to study the evolution of the AR magnetic properties during the five near-side passages, and a proxy to follow the magnetic flux changes when no magnetograms are available, i.e. during far-side transits. The ejectivity is studied by characterizing the angular widths, speeds and masses of 108 CMEs that we associated to the AR, when examining a 124-day period. Such an ejectivity tracking was possible thanks to the multi-viewpoint images provided by the Solar-Terrestrial Relations Observatory and Solar and Heliospheric Observatory in a quasi-quadrature configuration. We also inspected the X-ray flares registered by the GOES satellite and found 162 to be associated to the AR under study. Given the substantial number of ejections studied, we use a statistical approach instead of a single-event analysis. We found three well defined periods of very high CMEs activity and two periods with no mass ejections that are preceded or accompanied by characteristic changes in the AR magnetic flux, free magnetic energy and/or presence of electric currents. Our large sample of CMEs and long term study of a single AR, provide further evidence relating AR magnetic activity to CME and Flare production.Fil: Iglesias, Francisco Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Merenda, Luciano A.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Lopez Fuentes, Marcelo Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Lopez Fuentes, Marcelo Claudio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Ugarte Urra, Ignacio. Spece Sciences División. Naval Research Laboratory; Estados Unido

    Moving adsorption belt system for continuous bioproduct recovery

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    Protective renal effects of atrial natriuretic peptide: Where are we now?

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    Atrial natriuretic peptide belongs to the family of natriuretic peptides, a system with natriuretic, diuretic, and vasodilator effects that opposes to renin-angiotensin system. In addition to its classic actions, atrial natriuretic peptide exerts a nephroprotective effect given its antioxidant and anti-inflammatory properties, turning it as a beneficial agent against acute and chronic kidney diseases. This minireview describes the most relevant aspects of atrial natriuretic peptide in the kidney, including its renal synthesis, physiological actions through specific receptors, the importance of its metabolism, and its potential use in different pathological scenarios.Fil: Choi, Marcelo Roberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto Alberto C. Taquini de Investigaciones En Medicina Traslacional. - Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiologicas "prof. Dr. Alberto C. Taquini". Instituto Alberto C. Taquini de Investigaciones En Medicina Traslacional.; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Histología y Biología Celular; ArgentinaFil: Fernandez, Belisario Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; Argentina. Instituto Universidad de la Fundación "Héctor Barceló"; Argentin

    Controversias internacionales

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    Cada estado tiene sus propios metas y objetivos, el alcanzarlas constituye el móvil principal de su política exterior. Sin embargo, en la actualidad hay que afirmar que los Estados en sus relaciones mutuas son esencialmente interdependientes. Por múltiples razones, políticas, económicas, sicosociales, militares y tecnológicas, etc, ningún país puede obrar solo. Dentro de este contexto la búsqueda o conservación de la paz es uno de los factores que más gravita en la existencia y mantenimiento de las relaciones internacionales. Pero, precisamente por las especiales características, y el avance de la civilización contemporánea, la existencia de una paz duradera en el contexto mundial se ve constantemente amenazada. El peligro de que incluso una guerra mundial es, simplemente, demasiado grande. La paz requiere de la cooperación internacional en todos sus niveles y para que esta subsista la humanidad debe contar con normas y procedimientos de validez permanente que faciliten la solución de las controversias internacionales por medios pacíficos. Los estados, que por su esencia son soberanos e independientes y solo ellos por lo tanto pueden regular su forma de proceder y han comprendido que existe la necesidad absoluta de establecer normas precisas que regulen sus mutuas relaciones. A pesar de que cada Estado afirma persistentemente su soberanía, se ha llegado al convencimiento de la necesidad de que exista un proceso de autorregulación, sin que esto implique que su conducta se somete, sin límite, a una autoridad superior

    Sexual dimorphism in the loud calls of Azara’s owl monkeys (Aotus azarae): evidence of sexual selection?

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    Primates use different types of vocalizations in a variety of contexts. Some of the most studied types have been the long distance or loud calls. These vocalizations have been associated with mate defense, mate attraction, and resource defense, and it is plausible that sexual selection has played an important role in their evolution. Focusing on identified individuals of known sex and age, we evaluated the sexual dimorphism in a type of loud calls (hoots) in a population of wild owl monkeys (Aotus azarae) in Argentina. We found evidence of sexual dimorphism in call structure, with females and males only emitting one type of call, each differing in dominant frequency and Shannon entropy. In addition, both age-related and sex-specific differences in call usage were also apparent in response to the removal of one group member. Future acoustic data will allow us to assess if there are individual characteristics and if the structure of hoot calls presents differences in relation to the social condition of owl monkeys or specific sex responses to variants of hoot calls’ traits. This will provide deeper insights into the evolution of vocal mechanisms regulating pair bonding and mate choice strategies in this and other primate species.Leakey Foundation, Wenner-Gren Foundation, National Geographic Society, NSF, National Institute on Aging, University of Pennsylvania Research Foundation, Zoological Society of San Dieg

    The renin angiotensin system in the central nervous system

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    The first evidences indicating that angiotensin II (ANG II) was a peptide with action on the brain were shown in 1961 when it was found that the intraventricular injection of ANG II induces a centrally mediated pressor response. As a neuropeptide, ANG II belongs to the class of neuromodulators. The brain renin angiotensin system (RAS) exerts paracrine, autocrine and intracrine functions independently of circulating blood-borne ANG II which has a limited access to the brain by the blood-brain barrier (BBB) in the circumventricular organs (CVOs). Brain-generated ANG II controls several physiological processes like stimulation of thirst, water intake and sodium appetite, acting as a neurotransmitter in neurons of brain areas such as the Subfornical organ (SFO) and Organum vasculosum of the lamina terminalis (OVLT). Generated angiotensins (ANGs) at the central nervous system (CNS) also stimulate endocrine secretions like argininevasopressin (AVP), oxytocin (OT), corticotrophin-releasing hormone (CRH) and adenocorticotrophin (ACTH secretion). Brain ANG II modulates the sympathetic autonomic functions and regulates blood pressure by increasing AVP and ACTH secretion and modulating the baroceptor reflex and the sympathetic output. During the last decade it has been established that, apart from its classical actions, ANG II exhibits other effects induced by direct action on its receptors or via local effects of its metabolites . Thereby, central actions of ANGs are not exclusively associated with their traditional roles. Indeed, several studies have shown that central ANGs are also involved in sexual behavior, stress, learning, and memory.Fil: Choi, Marcelo Roberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Fisiopatología; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Cavallero, Carmen Susana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Cs.biologicas. Cat.de Fisiopatologia; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Fernandez, Belisario Enrique. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Fisiopatología; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
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