743 research outputs found

    Unambiguous Formalism for Higher-Order Lagrangian Field Theories

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    The aim of this paper is to propose an unambiguous intrinsic formalism for higher-order field theories which avoids the arbitrariness in the generalization of the conventional description of field theories, which implies the existence of different Cartan forms and Legendre transformations. We propose a differential-geometric setting for the dynamics of a higher-order field theory, based on the Skinner and Rusk formalism for mechanics. This approach incorporates aspects of both, the Lagrangian and the Hamiltonian description, since the field equations are formulated using the Lagrangian on a higher-order jet bundle and the canonical multisymplectic form on its dual. As both of these objects are uniquely defined, the Skinner-Rusk approach has the advantage that it does not suffer from the arbitrariness in conventional descriptions. The result is that we obtain a unique and global intrinsic version of the Euler-Lagrange equations for higher-order field theories. Several examples illustrate our construction.Comment: 21 pages; 4 diagrams; (this version) corrected typos; moved paragraphs; publishe

    Incidencia de eventos adversos asociados a dispositivosmédicos en una institución de salud en Colombia

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    Este artículo presenta los resultados de un estudio retrospectivo de eventos adversos asociados a dispositivos médicos (EADMS), presentados en el período de enero a junio de 2010 en el servicio de Cirugía de una institución prestadora de saludo (IPS) en Colombia.This paper presents the results of a retrospective study of adverse events associated with medical devices (AEAMDS), presented during the period of January through June of 2010 in the Surgery Department of a healthcare institution in Colombia

    Evaluación sanitaria en toros de fomento del departamento de Cundinamarca, 1. Estudios bacteriológicos

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    Se examinaron 46 toros de diferentes razas pertenecientes a 18 granjas de fomento, situadas en igual número de municipios del departamento de Cundinamarca. Estos animales fueron examinados 3 veces con intervalos de un mes para brucelosis, leptospirosis y salmonelosis mediante exámenes serológicos y para campilobacteriosis, brucelosis, trichomoniasis y otro tipo de gérmenes corrientes en lavados prepuciales. 11 toros (23.9 por ciento) fueron positivos a trichomoniasis, 8 (17.3 por ciento) a campilobacteriosis, 20 (43.4 por ciento) reactores a salmonelosis, 13 (28.2 por ciento) reactores a brucelosis, 24 (52.17 por ciento) reactores a leptospirosis. De todos los animales examinados, 35 (76.0 por ciento) positivos a una o varias entidades fueron mencionadas anteriormente. Estos toros en el transcurso de un año han servido un total de 812 vacas de los municipios donde están localizadas las fincas de Fomento y alrededor de las cuales hay una población de 511312 bovinos. Se discute las posibilidades de diseminación de las enfermedades y sus posibilidades de contro

    Impact of regulated and emerging pollutants and microplastics in marine ecosystems (IMPACTA project)

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    Marine ecosystems are nowadays subjected to a massive input of synthetic chemicals from everywhere. Unfortunately only a small portion of them is being monitored, and it is necessary to identify which pollutants can produce adverse impacts in the marine environment. IMPACTA project (CTM2013-48194-C3) is characterizing the distribution of regulated and emerging contaminants and microplastics in marine sediments, and evaluating the biological effects that they can cause (sing sublethal embryotoxicity tests, endocrine disruption and biomarkers). Sensitive and selective analytical methods are being developed and validated for pharmaceuticals, perfluorinated compounds, organophosphorus pesticides, triazines, personal care products, nonylphenols and alkylated PAHs in sediments. Thus, relevant pollutants present in coastal and offshore areas will be identified. Furthermore potential toxic effects of the contaminants present in coastal sediments are being assessed through embryotoxicity bioassays and also the biological effects on different marine species as a consequence of their exposition to specific compounds. Another relevant contribution of this project will be the assessment of the impact of micro-plastics, first time in the Spanish coastal areas. Their potential toxic effects and their role in the transference of pollutants in the marine environment are being assessed. The concentration and composition of microplastics in sediments and demersal fish stomachs are being characterized, and their potential biological effects on marine invertebrates are also being investigated

    Enfermedades causantes de abortos en cabras.

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    Se determinaron los títulos de anticuerpos de las siguientes enfermedades causantes de abortos en cabras de la sabana de Bogotá: brucelosis (asumiendo una reacción cruzada con Brucella melitensis), clamidiosis, letospirosis y toxoplasmosis. Un total de 200 muestras fueron analizadas, tomadas en 21 apriscos con una población de 1.033 animales. Para el primer caso, se encontró el 3.5 por ciento de reactores a Brucella abortus por medio de la prueba lenta en tubo (título 1:200), corroborando esta reactividad por medio de la prueba de mercaptoetanol (1:50) y fijación de complemento (1:64). Para determinar anticuerpos fijadores de complemento para Chlamydia psittachi, se comprobó que el uno por ciento fueron reactores con un rango de confianza del 95 por ciento y prueba diagnóstica específica para Chlamydia. En la leptospirosis se halló una prevalencia instantánea del 4 por ciento que representa los animales reactores. Unicamente 2 animales presentaron títulos de 1:100 y 1:400 para Leptospira icterohaemorrhagie. Las pruebas para toxoplasmosis mostraron que el 25 por ciento de los animales analizados fueron reactores a Toxoplasma gondi

    Nitric oxide sensing in plants is mediated by proteolytic control of group VII ERF transcription factors

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    Nitric oxide (NO) is an important signaling compound in prokaryotes and eukaryotes. In plants, NO regulates critical developmental transitions and stress responses. Here, we identify a mechanism for NO sensing that coordinates responses throughout development based on targeted degradation of plant-specific transcriptional regulators, the group VII ethylene response factors (ERFs). We show that the N-end rule pathway of targeted proteolysis targets these proteins for destruction in the presence of NO, and we establish them as critical regulators of diverse NO-regulated processes, including seed germination, stomatal closure, and hypocotyl elongation. Furthermore, we define the molecular mechanism for NO control of germination and crosstalk with abscisic acid (ABA) signaling through ERF-regulated expression of ABSCISIC ACID INSENSITIVE5 (ABI5). Our work demonstrates how NO sensing is integrated across multiple physiological processes by direct modulation of transcription factor stability and identifies group VII ERFs as central hubs for the perception of gaseous signals in plants

    Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

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    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range η<0.8|\eta| < 0.8 are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286

    Study of knowledge, attitudes, and practices related to leishmaniasis : evidence of government neglect in the Colombian Darién

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    ABSTRACT: American cutaneous leishmaniasis (ACL) is considered a public health problem worldwide, and incidence in Colombia is 12,000 cases per year. Colombia has implemented control programs for years which have often overlooked the social, economic, and demographic characteristics of the regions where the disease occurs. As part of an epidemiological study, this article presents the results of a survey on knowledge, attitudes, and practices (KAP) related to leishmaniasis in rural populations in Acandí in the Colombian Darién. Qualitative and quantitative tools were used (ethnography and surveys, respectively). The results show scarce knowledge among the population on basic aspects such as recognition of the sand fly vector. There were also differences in KAP according to gender and type of population, rather than by geographic area. The study points to government neglect as a critical factor in the persistence of the disease.RESUMEN: La leishmaniasis cutánea americana (LCA) es considerada un problema de salud pública a nivel mundial, y su incidencia en Colombia es de 12 mil casos por año. Durante años se han implementado programas de control, que frecuentemente ignoran características sociales, económicas y demográficas de las regiones afectadas. Como parte de un estudio de tipo epidemiológico, en este artículo se presentarán los resultados de un estudio sobre los conocimientos, actitudes y prácticas (CAP) frente a la leishmaniasis, que tienen las poblaciones de las zonas rurales del municipio de Acandí, en el Darién Colombiano. Para el estudio se utilizaron herramientas cualitativas como la etnografía y cuantitativas, como las encuestas dirigidas. Los resultados ponen en manifiesto el desconocimiento de la población en aspectos fundamentales como el reconocimiento del vector. Además, existen diferencias en las CAP por género y por tipo de población, pero no por su distribución geográfica. Se evidenció el abandono estatal como factor determinante en la perpetuación de la enfermedad.

    Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV

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    Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with pT0.5p_{\rm T}\geq0.5 GeV/c in η0.8|\eta|\leq0.8. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity (NchN_{\rm ch}) is reported for events with different pTp_{\rm T} scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low NchN_{\rm ch}, whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean pTp_{\rm T} with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.Comment: 21 pages, 9 captioned figures, 3 tables, authors from page 16, published version, figures from http://aliceinfo.cern.ch/ArtSubmission/node/308
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