2,498 research outputs found
Loss of largest and oldest individuals of the Montpellier snake correlates with recent warming in the southeastern Iberian Peninsula
The effects of climate change on organisms are now being extensively studied in many different taxa. However, the variation in body size, usually shrinkage in response to increasing temperature, has received little attention regarding to reptiles. During past periods of global warming, many organisms shrank in size, and current evidence and experiments manipulating temperature have shown a biomass decrease in some organisms with increasing temperatures. Here we test whether the body size of the Montpellier snake Malpolon monspessulanus from the southeastern Iberian Peninsula is changing and correlated with the increasing temperature in this region during a 39year period (1976–2014). We measured the snout–vent length (SVL) of vouchers in scientific collections to check for trends in adult body size at the population level in relation with temperature, while controlling for the age of the individuals (estimated by skeletochronology, n¼141). Given the great ontogenetic variation in body size of the study species, we categorized age in 3 classes: “young adults” (under 5 years old), “intermediate adults” (from 5 to 7 years old), and “old adults” (from 8 to 14 years old). By means of linear mixed models, we found a negative relationship between SVL of “old adults” and average annual temperature in the region during the lifetime of each individual. Our results indicate that largest and oldest individuals of the Montpellier Snake, that is, males because of strong sexual size dimorphism in this species, disappeared from the study population, and suggest that it occurred in response to rising environmental temperature.Junta de Andalucía RNM-25
Leptogenesis, neutrino masses and gauge unification
Leptogenesis is considered in its natural context where Majorana neutrinos
fit in a gauge unification scheme and therefore couple to some extra gauge
bosons. The masses of some of these gauge bosons are expected to be similar to
those of the heavy Majorana particles, and this can have important consequences
for leptogenesis. In fact, the effect can go both ways. Stricter bounds are
obtained on one hand due to the dilution of the CP-violating effect by new
decay and scattering channels, while, in a re-heating scheme, the presence of
gauge couplings facilitates the re-population of the Majorana states. The
latter effect allows in particular for smaller Dirac couplings.Comment: 11pages, 7 figures. v2: definition of the lepton asymmetry corrected,
small numerical changes for the baryon number, conclusion does not change;
typos corrected and references adde
Sinusitis maxilar iatrogénica tras la colocación de implantes: a propósito de un caso
La perforación del suelo del seno maxilar y de las fosas nasales durante la colocación de implantes en las crestas alveolares situadas por debajo no es un hecho infrecuente. Pequeñas comunicacio-nes producidas durante el fresado para la preparación del lecho implantario cierran espontánea-mente, pero es un requisito indispensable para evitar futuras complicaciones que el implante que-de estable, si no deberá ser retirado. Presentamos el caso de una mujer de 54 años de edad que acude refiriendo cacosmia y halitosis permanentes y episodios esporádicos de dolor en la zona infraorbitaria derecha asociados a rino-rrea purulenta, que no ceden a la administración de distintos antibióticos. Las pruebas radiológicas muestran tres implantes dentales en el primer cuadrante sustituyendo a 1.2, 1.3 y 1.6: el primero perforando la fosa nasal, y el tercero con el extremo apical en el interior del seno maxilar derecho con una imagen radioopaca bien delimitada asociada. Confirmada la existencia de una comunicación bucosinusal de más de dos años de evolución, y establecida esta como la causa del cuadro de sinusitis maxilar crónica que la paciente padece, se determina como plan de tratamiento la extracción de los tres implantes y la reconstrucción del plano óseo mediante un injerto de hueso autólogo de mentón. Al retirar el implante en posición 1.6 se observa material de aspecto resinoso adherido a toda su superficie, con fines probablemente retentivos, y que habrá contribuido en gran medida a incre-mentar el proceso irritativo local. El defecto remanente es tan importante en este sector que se hace imposible anclar un injerto óseo en este área, por lo que se legra la mucosa sinusal enferma a su través, enviando muestra para su posterior análisis anatomopatológico, y se consigue el cierre primario mediante un injerto pediculado de la bola adiposa de Bichat. Los controles postoperato-rios fueron favorables consiguiendo de esta forma la remisión total de la sintomatología y la recu-peración completa
Variaciones de la anatomía del nervio dentario inferior. Revisión bibliográfica
La correcta identificación del conducto dentario inferior o conducto mandibular, por el que discurre el nervio dentario inferior, es esencial cuando se precisa realizar cualquier intervención de Cirugía Bucal en la región mandibular posterior. En este artículo se revisa la literatura publicada referida a la anatomía del nervio dentario inferior y se relaciona con las diferentes técnicas de diagnóstico por la imagen (radiología y tomografía) así como con la disección anatómica de mandíbulas de cadáver, lo que nos permite conocer las variaciones en cuanto a la morfología, el recorrido del nervio dentario inferior por el interior de la mandíbula y sus relaciones con las diversas estructuras con las que entra en contacto
Geometrically induced singular behavior of entanglement
We show that the geometry of the set of quantum states plays a crucial role
in the behavior of entanglement in different physical systems. More
specifically it is shown that singular points at the border of the set of
unentangled states appear as singularities in the dynamics of entanglement of
smoothly varying quantum states. We illustrate this result by implementing a
photonic parametric down conversion experiment. Moreover, this effect is
connected to recently discovered singularities in condensed matter models.Comment: v2: 4 pags, 4 figs. A discussion before the proof of Proposition 1
and tomographic results were included, Propostion 2 was removed and the
references were fixe
Las complicaciones de la resonancia magnética nuclear en la exploración de la articulación temporomandibular
La presencia de ciertos materiales ferromagnéticos , implantes y aparatos metálicos en el organismo se considera una contraindicación relativa para la práctica de una resonancia magnética nuclear, debido a los riesgos asociados al desplazamiento o dislocación de los mismos al ser atraídos en el campo magnético a que se les somete. Se presenta un resumen sobre los materiales con un riesgo potencial de complicaciones durante la práctica de la resonancia magnética nuclear de la articulación temporomandibular y se destaca la importancia de la detección previa de los mismos mediante la anamnesis y la exploración fisica de los pacientes que precisan dicha técnica. En algunos casos, se precisará asesoramiento especializado
Obstacles and benefits of the implementation of a reduced-rank smoother with a high resolution model of the tropical Atlantic Ocean
Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic Ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Despite model's non-linearities and the various approximations used for its implementation, the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical points of view, as expected from linear theory. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the North Brazil Current rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational center systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network
Estilos arquitectónicos y estadios constructivos en el grupo May, Oxkintok, Yucatán.
Sin resume
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