5,948 research outputs found
Evaluation of magnetic terms in Cu4O4 cubane-like systems from selected configuration interaction calculations: A case study of polynuclear transition-metal systems
We present the evaluation of magnetic terms in a Cu4O4 cubane-like system from truncated CI calculations, as a case study of polynuclear transition-metal complexes. We employ a new excitation
selected configuration interaction (EXSCI) method based on the use of local orbitals. Taking advantage of the locality and then of the fact that the interactions vanish when the distance is large, the
dimension of the CI is largely reduced. To the best of our knowledge these CI calculations are the
largest one performed for polynuclear transition metal systems so far. The results show the presence
of two leading ferromagnetic interactions between bridged Cu ions. Also the interactions between
the unbridged Cu ions are ferromagnetic, but very weak, in contrast to the experimental data. The
nature and amplitude of all the computed interactions are consistent with the relative orientation
of the magnetic orbitals in the molecule, and correctly reproduce the susceptibility versus temperature curve. Our results indicate that it is possible to obtain similar fittings with sets of parameters
representing different physical effects and put in evidence the drawbacks of the fitting based on oversimplified magnetic models. In this context, the presented computational strategy can be considered
as a useful tool to help in the interpretation of the magnetic data and the validation of the magnetic interaction model in the polynuclear magnetic systems.Ministerio de Ciencia e Innovación de España-CTQ2009-0776
Steganalytic Methods for the Detection of Histogram Shifting Data Hiding Schemes
Peer-reviewedIn this paper, several steganalytic techniques designed to detect the existence of hidden messages using histogram shifting schemes are presented. Firstly, three techniques to identify specific histogram shifting data hiding schemes, based on detectable visible alterations on the histogram or abnormal statistical distributions, are suggested. Afterwards, a general technique capable of detecting all the analyzed histogram shifting data hiding methods is suggested. This technique is based on the effect of histogram shifting methods on the ¿volatility¿ of the histogram of the difference image. The different behavior of volatility whenever new data are hidden makes it possible to identify stego and cover images
Ressenyes
Index de les obres ressenyades: Blanca VALENZUELA ; Emilia CASTILLO OCHOA (eds.), Educación, comunicación y nuevas perspectivas metodológicas en las ciencias sociale
Agricultura específica por sitio compartiendo experiencias
Debido a la diversidad de paisajes productivos, Colombia reúne un enorme potencial frutícola y, por lo tanto, una gran cantidad de oportunidades para la producción de frutas. Sin embargo, definir el sitio, el frutal y las prácticas de manejo adecuadas son los principales desafíos a los que se enfrentan los productores de frutas en este país. El sector cuenta con poca información confiable acerca de los factores y condiciones que conducen a obtener altas producciones en cada uno de los paisajes productivos. No obstante, existe en el país una gran cantidad de experiencias, unas más exitosas que otras, y que son llevadas a cabo en las mismas fincas de los productores, pero que infortunadamente no han sido registradas. Nuestra premisa es que si pudiéramos reunir dichas experiencias, podríamos analizarlas y proveer a los fruticultores con recomendaciones de sitios específicos, que servirían como base para la toma de decisiones acerca del sitio dónde sembrar, qué cultivo sembrar y/o las prácticas de manejo más apropiadas para implementar
Supporting task creation inside FPGA devices
The most common model to use co-processors/accelerators
is the master-slave model where the slaves (coprocessors/
accelerators) are driven by a general purpose
cpu. This simplifies the management of the accelerators
because they cannot actively interact with the runtime and
they are just passive slaves that operate over the memory
under demand. However, the master-slave model limits system
possibilities and introduces synchronization overheads that
could be avoided.
To overcome those limitations and increase the possibilities
of accelerators, we propose extending task based programming
models (like OpenMP [1] or OmpSs) to support some runtime
APIs inside the FPGA co-processor. As a proof-of-concept,
we implemented our proposal over the OmpSs@FPGA environment
[2] adding the needed infrastructure in the FPGA
bitstream and modifying the existing tools to support creation
of children tasks inside a task offloaded to an FPGA accelerator.
In addition, we added support to synchronize the children
tasks created by a FPGA task regardless they are executed in a
SMP host thread or they also target another FPGA accelerator
in the same co-processor
Multi-task Implementation for Image Reconstruction of an AER Communication
Address-Event-Representation (AER) is a communication protocol
for transferring spikes between bio-inspired chips. Such systems may consist of
a hierarchical structure with several chips that transmit spikes among them in
real time, while performing some processing. There exist several AER tools to
help in developing and testing AER based systems. These tools require the use
of a computer to allow the processing of the event information, reaching very
high bandwidth at the AER communication level. We propose to use an
embedded platform based on multi-task operating system to allow both, the
AER communication and the AER processing without a laptop or a computer.
We have connected and programmed a Gumstix computer to process Address-
Event information and measured the performance referred to the previous AER
tools solutions. In this paper, we present and study the performance of a new
philosophy of a frame-grabber AER tool based on a multi-task environment,
composed by the Intel XScale processor governed by an embedded GNU/Linux
system.Ministerio de Ciencia e Innovación TEC2006-11730-C03-0
LightDock: a new multi-scale approach to protein–protein docking
Computational prediction of protein–protein complex structure by docking can provide structural and mechanistic insights for protein interactions of biomedical interest. However, current methods struggle with difficult cases, such as those involving flexible proteins, low-affinity complexes or transient interactions. A major challenge is how to efficiently sample the structural and energetic landscape of the association at different resolution levels, given that each scoring function is often highly coupled to a specific type of search method. Thus, new methodologies capable of accommodating multi-scale conformational flexibility and scoring are strongly needed.
We describe here a new multi-scale protein–protein docking methodology, LightDock, capable of accommodating conformational flexibility and a variety of scoring functions at different resolution levels. Implicit use of normal modes during the search and atomic/coarse-grained combined scoring functions yielded improved predictive results with respect to state-of-the-art rigid-body docking, especially in flexible cases.B.J-G was supported by a FPI fellowship from the Spanish Ministry of Economy and
Competitiveness. This work was supported by I+D+I Research Project grants BIO2013-48213-R and BIO2016-79930-R from the Spanish Ministry of Economy
and Competitiveness. This work is partially supported by the European Union H2020
program through HiPEAC (GA 687698), by the Spanish Government through Programa
Severo Ochoa (SEV-2015-0493), by the Spanish Ministry of Science and
Technology (TIN2015-65316-P) and the Departament d’Innovació, Universitats i
Empresa de la Generalitat de Catalunya, under project MPEXPAR: Models de Programaciói Entorns d’Execució Paral·lels (2014-SGR-1051).Peer ReviewedPostprint (author's final draft
Antonio Valiente Romero (coord.). Los capuchinos y la capilla de San José: un siglo de convivencia (1916-2016) [Reseña]
Reseña completa: Antonio Valiente Romero (coord.). Los capuchinos y la capilla de San José: un
siglo de convivencia (1916-2016). Sevilla: Editorial Vitela, 2016, 208 pp. ISBN:
978-84-944659-3-2
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