3,667 research outputs found

    Questing for Algebraic Mass Dimension One Spinor Fields

    Full text link
    This work deals with new classes of spinors of mass dimension one in Minkowski spacetime. In order to accomplish it, the Lounesto classification scheme and the inversion theorem are going to be used. The algebraic framework shall be revisited by explicating the central point performed by the Fierz aggregate. Then the spinor classification is generalized in order to encompass the new mass dimension one spinors. The spinor operator is shown to play a prominent role to engender the new mass dimension one spinors, accordingly.Comment: 7 pages, final version to appear in Eur. Phys. J.

    On the bilinear covariants associated to mass dimension one spinors

    Full text link
    In this paper we approach the issue of Clifford algebra basis deformation, allowing for bilinear covariants associated to Elko spinors which satisfy the Fierz-Pauli-Kofink identities. We present a complete analysis of covariance, taking into account the involved dual structure associated to Elko. Moreover, the possible generalizations to the recently presented new dual structure are performed.Comment: 9 pages, 0 figure

    Neuroendocrine Regulation of Metabolism

    Get PDF
    Given the current environment in most developed countries, it is a challenge to maintain a good balance between calories consumed and calories burned, although maintenance of metabolic balance is key to good health. Therefore, understanding how metabolic regulation is achieved and how the dysregulation of metabolism affects health is an area of intense research. Most studies focus on the hypothalamus, which is a brain area that acts as a key regulator of metabolism. Among the nuclei that comprise the hypothalamus, the arcuate nucleus is one of the major mediators in the regulation of food intake. The regulation of energy balance is also a key factor ensuring the maintenance of any species as a result of the dependence of reproduction on energy stores. Adequate levels of energy reserves are necessary for the proper functioning of the hypothalamic-pituitary-gonadal axis. This review discusses valuable data presented in the 2015 edition of the International Workshop of Neuroendocrinology concerning the fundamental nature of the hormonal regulation of the hypothalamus and the impact on energy balance and reproduction.Fil: Cornejo, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Hentges, S.T.. State University of Colorado - Fort Collins; Estados UnidosFil: Maliqueo, M.. Universidad de Chile; ChileFil: Coirini, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Becu Villalobos, D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Elias, C. F.. University of Michigan; Estados Unido

    On the Spinor Representation

    Full text link
    A systematic study of the spinor representation by means of the fermionic physical space is accomplished and implemented. The spinor representation space is shown to be constrained by the Fierz-Pauli-Kofink identities among the spinor bilinear covariants. A robust geometric and topological structure can be manifested from the spinor space, wherein, for instance, the first and second homotopy groups play prominent roles on the underlying physical properties, associated to the fermionic fields.Comment: 16 page

    Point sets that minimize (k)(\le k)-edges, 3-decomposable drawings, and the rectilinear crossing number of K30K_{30}

    Get PDF
    There are two properties shared by all known crossing-minimizing geometric drawings of KnK_n, for nn a multiple of 3. First, the underlying nn-point set of these drawings has exactly 3(k+22)3\binom{k+2}{2} (k)(\le k)-edges, for all 0k<n/30\le k < n/3. Second, all such drawings have the nn points divided into three groups of equal size; this last property is captured under the concept of 3-decomposability. In this paper we show that these properties are tightly related: every nn-point set with exactly 3(k+22)3\binom{k+2}{2} (k)(\le k)-edges for all 0k<n/30\le k < n/3, is 3-decomposable. As an application, we prove that the rectilinear crossing number of K30K_{30} is 9726.Comment: 14 page

    Evaluación de cultivares locales e introducidos de (RICINUS COMMUNIS L) higuerilla para condiciones de selva del Peru Región Ucayali 2011.

    Get PDF
    El experimento se instalo en el anexo experimental “Los Incas” de la Estación Experimental Agraria Pucallpa, departamento de Ucayali, provincia de Coronel Portillo, distrito de campo verde, el suelo donde se instalo el experimento es de altura o Ultisols. El diseño empleado fue de block completo randomizado con 04 tratamientos y 04 repeticiones, teniendo un total de 16 unidades experimentales, en un área de 1,881 m2. , los tratamientos evaluados fueron: T1 = Higuerilla BRS Nordestina, T2 = Higuerilla L1-003, T3 = Higuerilla L2-004 y T4 = Higuerilla L3-007. Se obtuvo como resultado que en las evaluaciones fenológicas en los cuatro cultivares donde para los parámetros agronómicos Higuerilla L3 – 007 e Higuerilla L 2-004, obtuvieron menor altura de planta al final del ciclo con 90 y 105 cm respectivamente siendo menor también en lo que corresponde a la altura de planta a la emisión del primer racimo que fue de 27.5 y 41 cm; asimismo el ecotipo Higuerilla L1 – 003 obtuvo 84 días a la emisión del primer racimo y 124 días a la cosecha del primer racimo siendo el más precoz con respecto a Higuerilla BRS Nordestina que obtuvo 147 días a la cosecha del primer racimo. Sin embargo en el parámetro de rendimiento de grano los ecotipos Higuerilla BRS Nordestina e Higuerilla L 2-004, rindieron un total de 602 y 524.8 kilos/ha respectivamente pero no superaron los 1,500 kg/ha

    Latitudinal extension of low-latitude scintillations measured with a network of GPS receivers

    Get PDF
    International audienceA latitudinal-distributed network of GPS receivers has been operating within Colombia, Peru and Chile with sufficient latitudinal span to measure the absolute total electron content (TEC) at both crests of the equatorial anomaly. The network also provides the latitudinal extension of GPS scintillations and TEC depletions. The GPS-based information has been supplemented with density profiles collected with the Jicamarca digisonde and JULIA power maps to investigate the background conditions of the nighttime ionosphere that prevail during the formation and the persistence of plasma depletions. This paper presents case-study events in which the latitudinal extension of GPS scintillations, the maximum latitude of TEC depletion detections, and the altitude extension of radar plumes are correlated with the location and extension of the equatorial anomaly. Then it shows the combined statistics of GPS scintillations, TEC depletions, TEC latitudinal profiles, and bottomside density profiles collected between September 2001 and June 2002. It is demonstrated that multiple sights of TEC depletions from different stations can be used to estimate the drift of the background plasma, the tilt of the plasma plumes, and in some cases even the approximate time and location of the depletion onset. This study corroborates the fact that TEC depletions and radar plumes coincide with intense levels of GPS scintillations. Bottomside radar traces do not seem to be associated with GPS scintillations. It is demonstrated that scintillations/depletions can occur when the TEC latitude profiles are symmetric, asymmetric or highly asymmetric; this is during the absence of one crest. Comparison of the location of the northern crest of the equatorial anomaly and the maximum latitude of scintillations reveals that for 90% of the days, scintillations are confined within the boundaries of the 50% decay limit of the anomaly crests. The crests of the anomaly are the regions where the most intense GPS scintillations and the deepest TEC depletions are encountered. In accord with early results, we observe that GPS scintillations/TEC depletions mainly occur when the altitude of the magnetic equator F-region is above 500km. Nevertheless, in many instances GPS scintillations and TEC depletions are observed to exist when the F-layer is well below 500km or to persist when the F-layer undergoes its typical nighttime descent. Close inspection of the TEC profiles during scintillations/depletions events that occur when the equatorial F-layer peak is below 500km altitude reveals that on these occasions the ratio of the crest-to-equator TEC is above 2, and the crests are displaced 10° or more from the magnetic equator. When the equatorial F-layer is above 500km, neither of the two requirements is needed, as the flux tube seems to be inherently unstable. We discuss these findings in terms of the Rayleigh-Taylor instability (RTI) mechanism for flux-tube integrated quantities. We advance the idea that the seeming control that the reverse fountain effect exerts on inhibiting or suppressing GPS scintillations may be related to the redistribution of the density and plasma transport from the crests of the anomaly toward the equatorial region and then to much lower altitudes, and the simultaneous decrease of the F-region altitude. These two effects originate a decrease in the crest/trough ratio and a reduction of the crests separation, making the whole flux tube more stable to the RTI. The correspondence between crest separation, altitude of the equatorial F-region, the onset of depletions, and the altitude (latitude) extension of plumes (GPS scintillations) can be used to track the fate of the density structures

    Planificacion y mantencion de una maquina centrifuga continua K850 S, ubicada en Planta IANSA-CURICO

    Get PDF
    178 p.La constante renovación y los continuos avances tecnológicos hacen de las máquinas un punto de vital importancia, dentro del proceso productivo de una industria. En Chile, solo las grandes industrias han dado importancia a la mantención que sus plantas productivas mediante una mantención preventiva de ellas. En cambio, en la mediana y pequeña industria se ha adaptado la modalidad de reparar cuando las fallas se presentan, sin haberlas previsto. Debido a la gran importancia que una maquinaria cumple dentro de un proceso productivo industrial, el estudio de esta tesis comprenderá las maquinas centrifugas K850 S, por ser estas de gran importancia en la elaboración del azúcar. Las Máquinas centrífugas son empleadas mundialmente en las industrias azucareras, para se-parar los cristales de azúcar del siropo madre en una masa cocida. Esta preparación se realiza mediante el uso de la fuerza centrífuga, el Tes. elegido surgió debido a la posibilidad que tuvimos de ingresar a la Planta IANSA de Curico, la que se hallaba en pleno periodo de mantención. La tesis se desarrollara en cuatro capítulos, En el primer capítulo se analiza el proceso industrial Para la elaboración del azúcar y la función de la centrífuga dentro del proceso. En el segundo capítulo se da a conocer la planificación actual en Planta IANSA Curico, y se propone además una planificación de la mantención para la Planta. El Capítulo tercero consta de un estudio de la mantención en forma teórica, describiendo los diferentes tipos de mantención. Posteriormente se da a conocer la mantención que actualmente se realiza en la Planta a la Centrífuga F850 S, y además se dan a conocer las consideraciones que se deben tomar en cuenta para implementar un Plan de Mantención preventiva. También en este capítulo se propone un nuevo plan de mantenimiento para la Centrífuga K850 S. En el capítulo cuarto se hace un estudio económico de la mantención actual y mantención propuesta; se calcula también la depreciación de la maquina por dos métodos y se compara con los costos de mantención actual y propuestas

    On extending actions of groups

    Full text link
    Problems of dense and closed extension of actions of compact transformation groups are solved. The method developed in the paper is applied to problems of extension of equivariant maps and of construction of equivariant compactifications
    corecore