Comments on space-time signature

In terms of three signs associated to two vectors and to a 2-plane, a formula for the signature of any four-dimensional metric is given. In the process, a simple expression for the sign of the Lorentzian metric signature is obtained. The rela- tionship between these results and those already known are commented upon

Mascotas: una mirada ético-social a la crueldad normalizada

El presente documento es un ejercicio reflexivo ético de las relaciones y consideraciones en la posesión de animales a modo de mascotas en ambientes urbanos. Se realiza un cuestionamiento de las preocupaciones morales de cuidado y respeto frente a los animales, argumentamos que el aparente trato ideal de atención a las mascotas expone un maltrato normalizado, cargado de egoísmo, soberbia, falta de civilidad y muestras de vacío existencial.ITESO, A. C

Positioning systems in Minkowski space-time: Bifurcation problem and observational data

In the framework of relativistic positioning systems in Minkowski space-time, the determination of the inertial coordinates of a user involves the {\em bifurcation problem} (which is the indeterminate location of a pair of different events receiving the same emission coordinates). To solve it, in addition to the user emission coordinates and the emitter positions in inertial coordinates, it may happen that the user needs to know {\em independently} the orientation of its emission coordinates. Assuming that the user may observe the relative positions of the four emitters on its celestial sphere, an observational rule to determine this orientation is presented. The bifurcation problem is thus solved by applying this observational rule, and consequently, {\em all} of the parameters in the general expression of the coordinate transformation from emission coordinates to inertial ones may be computed from the data received by the user of the relativistic positioning system.Comment: 10 pages, 7 figures. The version published in PRD contains a misprint in the caption of Figure 3, which is here amende

Fecal Metabolomics Insights of Agavins Intake in Overweight Mice

Targeted and non-targeted metabolite profiling can identify biomarkers after a dietary treatment leading to a better understanding of interactions between diet and health. This study was conducted to establish enriched or depleted metabolites in the feces of overweight mice after a diet shift plus agavins or inulins supplementation, and their possible association with beneficial effects on host health. Thirty-eight male C57BL/6 mice were fed with a high-fat diet for 5 weeks followed by a diet shift to a standard diet supplemented with agavins (HF-ST + A) or inulins (HF-ST + I) for five more weeks. Feces were collected before and after prebiotic supplementation for metabolomics analyses. HF-ST + I group increased the fecal excretion of two methyl esters: linoleic and oleic acid, while HF-ST + A mice showed a substantial augment of 2-decenal, fructose, cyclohexanol, and the acids: 10-undecenoic, 3-phenyllactic, nicotinic, 5-hydroxyvaleric, and lactic. From the metabolites identified in HF-ST + A, only lactic acid has been reported previously and associated with beneficial effects on host health. However, the identification of new metabolites, coming from the microbial fermentation of agavins, opens opportunities to transform this information into practical solutions to tackle overweight and associated metabolic syndrome

Anatomy of the “false thumb” of Tremarctos ornatus (Carnivora, Ursidae, Tremarctinae) : phylogenetic and functional implications

Se describe por primera vez el sesamoideo radial o “falso pulgar” del oso de anteojos (Tremarctos ornatus), mostrando la gran similitud morfológica con el del panda gigante (Ailuropoda melanoleuca) y las diferencias que presenta con el resto de los Ursidae. Esto apunta a la existencia de un origen común para esta estructura en ambas especies, pero considerando las filogenias aceptadas de Ursidae, la presencia de falso pulgar en T. ornatus y A. melanoleuca sería una simplesiomorfía respecto al resto de úrsidos, en los cuales el sesamoideo radial nunca aumentó de tamaño, careciendo de la especializada función que posee en Tremarctinae y Ailuropodinae.We describe for the first time the radial sesamoid or “false thumb” of the spectacled bear (Tremarctos ornatus), showing its great morphological similarities with that of the giant panda (Ailuropoda melanoleuca) and the differences with that of the rest of the Ursidae. This points to the existence of a common origin for this structure in both species, but considering the accepted phylogenies of ursids, the sharing of a “false thumb” in T. ornatus and A. melanoleuca would be a plesiomorphy for these groups, whereas in the rest of the ursids the radial sesamoid was probably reduced, lacking the specialised function that this bone has in Tremarctinae and [email protected] [email protected]

Morphological, molecular and pathogenic characterization of Phytophthora palmivora isolates causing black pod rot of cacao in Colombia

Aim of study: To characterize isolates of Phytophthora sp. causing black pod rot (BPR) of cacao (Theobroma cacao L.).Area of study: Eight cocoa-growing regions in Colombia.Material and methods: Sixty isolates of Phytophthora sp. were obtained from tissues of cacao pods showing symptoms of BPR. Isolates were characterized using the morphology of sporangia and chlamydospores, molecular sequencing of regions of nuclear DNA (rDNA-ITS) and mitochondrial (COX) and virulence in different genotypes of cocoa pods.Main results: A high phenotypic variability between the isolates was determined, being the pedicel length and the length/width ratio (L/W) the most stable characters for species identification. Short pedicels with an average of 3.13 μm ± 0.28 and a length/width ratio of sporangia (L/W) with an average of 1.55 μm ± 0.11 were established as the most consistent morphological characteristics within palmivora species.Research highlights: Phytophthora pamivora was the only species associated to BPR, identified using morphology together with sequence analyses

3D mechanical characterization of artificial muscles with stereoscopic computer vision and active contours

Artificial muscles are formed by attaching a conducting polymeric film to a non-conducting one. Applying an electrical current on the muscle. a macroscopic bending movement appears on it. Study of curvature variations and related parameters, such as speed of motion or energy of curvature, is necessary for improving the efficiency of these devices. In a previous work. a one-cam computer vision system was developed to estimate motion parameters in 2D with precise results. In this paper, a two-cam stereo vision system is proposed to process the image sequence and track the muscle in 3D. Active contours models are employed in motion detection and mechanical parameters estimation. Results prove the validity of this approach, allowing automatic testing on the research into artificial muscles.This work was supported by MCYI' BQLJ2001-047

Perspectivas de los estudios de arqueomagnetismo en Sudamérica

Archaeomagnetism is the study of past geomagnetic field variations using bricks, pottery and campfire stones. This is a multidisciplinary work in which archaeologists, historians and geophysicists play important roles. For geophysicists, it contributes to the reconstruction and the study of local and global variations of the geomagnetic field, and it can serve as a dating tool for historical studies. However, this technique goes far beyond the chronological application, as it may provide information for paleoenvironmental studies and the provenance of objects. These studies are well developed in Europe, where there are records since the Middle Ages and a wide variety of recent data; on the contrary, data are scarce in the Southern Hemisphere, although several collaborative initiatives have enabled to make significant progress in recent years.El Arqueomagnetismo es el estudio de cambios y variaciones en el campo magnético terrestre en el pasado a partir de objetos, estructuras y materiales de construcción antiguos. Se trata de un trabajo multidisciplinario entre arqueólogos, historiadores y geofísicos. Para los geofísicos contribuye a la reconstrucción y al estudio de las variaciones globales y locales del campo geomagnético, mientras que para los estudios históricos, constituye fundamentalmente una herramienta de datación. Sin embargo, esta técnica va más allá de las aplicaciones cronológicas, pudiendo aportar información para los estudios paleoambientales y de procedencia de objetos. Los estudios de este tipo están muy desarrollados en Europa, donde se cuenta con registros desde el medioevo y una enorme cantidad de análisis recientes, pero hasta el momento los antecedentes en el hemisferio Sur son muy escasos, aunque se está progresando rápidamente con la colaboración entre distintas instituciones en los últimos años.Fil: Greco Mainero, Mariano Catriel. Universidad Nacional Autónoma de México; MéxicoFil: Goguichaishvili, Avto. Universidad Nacional Autónoma de México; MéxicoFil: Morales, Juan. Universidad Nacional Autónoma de México; MéxicoFil: Bocco, G.. Universidad Nacional Autónoma de México; MéxicoFil: Gogorza, Claudia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; ArgentinaFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin

Influence of colloid suspensions of humic acids on the alkaline hydrolysis of N-methyl-N-nitroso-p-toluene sulfonamide

The influence of humic substances (HSs) upon the alkaline hydrolysis of N-methyl-N-nitroso-p-toluene sulfonamide has been studied. Important inhibition of hydrolysis reaction has been reported. This inhibition has been explained in terms of association of reactants to the humic substances. Kinetic results have been modeled using the micellar pseudophase model. © 2010 Wiley Periodicals, Inc.Fil: Astray, G.. Universidad de Vigo; EspañaFil: García Río, L.. Universidad de Santiago de Compostela; EspañaFil: Lodeiro, Anibal. Universidad de Vigo; EspañaFil: Mejuto, Juan Carlos. Universidad de Vigo; EspañaFil: Moldes, O.. Universidad de Vigo; EspañaFil: Morales, J.. Universidad de Vigo; EspañaFil: Moyano, Fernando. Universidad de Vigo; España. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentin

¿El uso de intensificador de imágenes en la realización de la osteotomía periacetabular disminuye la incidencia de complicaciones y mejora la orientación acetabular? Fundación Universitaria Ciencias de la Salud / Hospital Universitario Clínica San Rafael 2008-2010

Se considera que la displasia acetabular primaria, representa una causa de artrosis secundaria precoz de la cadera, ya que un pequeño ángulo centro borde deja la superficie lateral de la superficie articular de la cabeza femoral, sin cobertura. Este fenómeno determina unas presiones elevadas sobre la zona de carga de las superficies articulares de la cadera, produciendo los cambios degenerativos precoces. En los pacientes con artrosis secundaria a displasia acetabular primaria, es preferible reconstruir el acetábulo que realizar una osteotomía femoral, ya que el proceso artrósico se localiza en la cara acetabular de la articulación. (1), (4), (9), (11