13,099 research outputs found
GPU acceleration of brain image proccessing
Durante los últimos años se ha venido demostrando el alto poder computacional
que ofrecen las GPUs a la hora de resolver determinados problemas.
Al mismo tiempo, existen campos en los que no es posible beneficiarse completamente
de las mejoras conseguidas por los investigadores, debido principalmente
a que los tiempos de ejecución de las aplicaciones llegan a ser extremadamente
largos. Este es por ejemplo el caso del registro de imágenes en medicina.
A pesar de que se han conseguido aceleraciones sobre el registro de imágenes,
su uso en la práctica clínica es aún limitado. Entre otras cosas, esto se debe
al rendimiento conseguido.
Por lo tanto se plantea como objetivo de este proyecto, conseguir mejorar los
tiempos de ejecución de una aplicación dedicada al resgitro de imágenes en medicina,
con el fin de ayudar a aliviar este problema
Electrorotation of semiconducting microspheres
We study experimentally the electrorotation (ROT) of semiconducting microspheres. ZnO microspheres obtained by a hydrothermal synthesis method are dispersed in KCl aqueous solutions and subjected to rotating electric fields. Two ROT peaks are found in experiments: a counterfield peak and a cofield peak at somewhat higher frequencies. These observations are in accordance with recent theoretical predictions for semiconducting spheres. The counterfield rotation is originated by the charging of the electrical double layer at the particle-electrolyte interface, while the cofield rotation is due to the Maxwell-Wagner relaxation. Additionally, we also found that some microspheres in the sample behaved differently and only showed counterfield rotation. We show that the behavior of these particles can be described by the so-called shell model. The microstructure of the microspheres is analyzed with electron microscope techniques and related to the ROT measurements.Spanish Government Ministry MICINN under Contract No. PGC2018-099217-B-I00Junta de Andalucía Contract No. PEJUS-
Primordial dark energy from a condensate of spinors in a 5D vacuum
We explore the possibility that the expansion of the universe can be driven
by a condensate of spinors which are free of interactions on a 5D relativistic
vacuum defined on an extended de Sitter spacetime which is Riemann-flat. The
extra coordinate is considered as noncompact. After making a static foliation
on the extra coordinate, we obtain an effective 4D (inflationary) de Sitter
expansion which describes an inflationary universe. We found that the
condensate of spinors here studied could be an interesting candidate to explain
the presence of dark energy in the early universe. The dark energy density
which we are talking about is poured into smaller sub-horizon scales with the
evolution of the inflationary expansion.Comment: Accepted in Advances in High Energy Physic
On nilspace systems and their morphisms
A nilspace system is a generalization of a nilsystem, consisting of a compact
nilspace X equipped with a group of nilspace translations acting on X. Nilspace
systems appear in different guises in several recent works, and this motivates
the study of these systems per se as well as their relation to more classical
types of systems. In this paper we study morphisms of nilspace systems, i.e.,
nilspace morphisms with the additional property of being consistent with the
actions of the given translations. A nilspace morphism does not necessarily
have this property, but one of our main results shows that it factors through
some other morphism which does have the property. As an application we obtain a
strengthening of the inverse limit theorem for compact nilspaces, valid for
nilspace systems. This is used in work of the first and third named authors to
generalize the celebrated structure theorem of Host and Kra on characteristic
factors.Comment: 16 pages, 4 figures. Referee's comments incorporated, yielding
several improvements in the exposition, especially in section 4. Accepted in
Ergodic Theory and Dynamical System
Two new species of Ammothea (Pycnogonida, Ammotheidae) from Antarctic waters
Two new species of the genus Ammothea are
described from Elephant Island and the South Shetlands
Islands, Antarctica. The material was captured during the
Polarstern cruise XXIII/8 to the Antarctic Peninsula area.
The main features of Ammothea pseudospinosa n. sp. are a
proboscis distinctly trilobulated distally with a constriction
at 2/3 of its length and dimorphism between the propodi of
the anterior (first and second) and posterior (third and
fourth) legs, and a trunk: proboscis length ratio of about
1.5. The main features of Ammothea childi n. sp. are a
cylindrical proboscis, longer than trunk length, and adults
with functional chelifores. These species are compared
with their closest congeners from the Southern Ocean:
A. pseudospinosa n. sp. with Ammothea spinosa and
Ammothea allopodes;A. childi n. sp. withAmmothea gigantea,
Ammothea bicorniculata and Ammothea hesperidensis
Seasonal decline in breeding performance of the Kelp Gull Larus dominicanus
The effects of timing of breeding on reproductive parameters of Kelp Gulls Larus dominicanus were studied in Patagonia, Argentina, during 1998 and 1999. Yearly and spatial variation in the study were assessed by sampling nests during two field seasons and in different areas within the colony, and accounted for variation with respect to breeding synchrony and breeding density. In both years and in three study areas, individuals laying earlier had higher hatching success, a larger number of chicks fledged, heavier chicks at one month and higher breeding success. Significant variation between study areas within the colony and between years was observed only for breeding success and number of chicks fledged. No effects of breeding synchrony on breeding parameters were detected. Timing of breeding, independent of study year and area, had no effect on either clutch size or egg size. Our results document for the first time the seasonal decline in breeding performance in the Kelp Gull, a species widely distributed in the southern hemisphere.Fil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Moreno, Juan. Consejo Superior de Investigaciones Científicas; EspañaFil: Potti Sánchez, Jaime. Consejo Superior de Investigaciones Científicas; Españ
Continuous Choreographies as Limiting Solutions of -body Type Problems with Weak Interaction
We consider the limit of -body type problems with weak
interaction, equal masses and -homogeneous potential, . We
obtain the integro-differential equation that the motions must satisfy, with
limit choreographic solutions corresponding to travelling waves of this
equation. Such equation is the Euler-Lagrange equation of a corresponding
limiting action functional. Our main result is that the circle is the absolute
minimizer of the action functional among zero mean (travelling wave) loops of
class
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