1,219 research outputs found
The INTEGRAL-OMC Scientific Archive
The Optical Monitoring Camera (OMC) on-board the INTEGRAL satellite has, as
one of its scientific goals, the observation of a large number of variable
sources previously selected. After almost 6 years of operations, OMC has
monitored more than 100 000 sources of scientific interest. In this
contribution we present the OMC Scientific Archive
(http://sdc.laeff.inta.es/omc/) which has been developed to provide the
astronomical community with a quick access to the light curves generated by
this instrument.We describe the main characteristics of this archive, as well
as important aspects for the users: object types, temporal sampling of light
curves and photometric accuracy.Comment: 4 pages, 5 figures. "Highlights of Spanish Astrophysics V"
Proceedings of the VIII Scientific Meeting of the Spanish Astronomical
Society (SEA) held in Santander, July 7-11, 200
Modeling and Simulation of Task Allocation with Colored Petri Nets
The task allocation problem is a key element in the solution of several applications from different engineering fields. With the explosion of the amount of information produced by the today Internet-connected solutions, scheduling techniques for the allocation of tasks relying on grids, clusters of computers, or in the cloud computing, is at the core of efficient solutions. The task allocation is an important problem within some branch of the computer sciences and operations research, where it is usually modeled as an optimization of a combinatorial problem with the inconvenience of a state explosion problem. This chapter proposes the modeling of the task allocation problem by the use of Colored Petri nets. The proposed methodology allows the construction of compact models for task scheduling problems. Moreover, a simulation process is possible within the constructed model, which allows the study of some performance aspects of the task allocation problem before any implementation stage
Recent activity of the Be/X-ray binary system SAX J2103.5+4545
Aims. We present a multiwavelength study of the Be/X-ray binary system SAX
J2103.5+4545 with the goal of better characterizing the transient behaviour of
this source.
Methods. SAX J2103.5+4545 was observed by Swift-XRT four times in 2007 from
April 25 to May 5, and during quiescence in 2012 August 31. In addition, this
source has been monitored from the ground-based astronomical observatories of
El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra
Nevada (Granada, Spain) since 2011 August, and from the TUBITAK National
Observatory (Antalya, Turkey) since 2009 June. We have performed spectral and
photometric temporal analyses in order to investigate the different states
exhibited by SAX J2103.5+4545.
Results. In X-rays, an absorbed power law model provided the best fit for all
the XRT spectra. An iron-line feature at ~6.42 keV was present in all the
observations except for that taken during quiescence in 2012. The photon
indexes are consistent with previous studies of SAX J2103.5+4545 in high/low
luminosity states. Pulsations were found in all the XRT data from 2007
(2.839(2) mHz; MJD 54222.02), but not during quiescence. Both optical outbursts
in 2010 and 2012 lasted for about 8/9 months (as the one in 2007 probably did
and the current one in 2014 might do) and were most probably caused by mass
ejection events from the Be star that eventually fed the circumstellar disc.
All of these outbursts started about 3 months before the triggering of the
X-ray activity, and about the same period before the maximum of the H_alpha
line equivalent width (in emission) was reached at only ~ -5 \AA. In this work
we found that the global correlation between the BV variability and the X-ray
intensity was also observed at longer wavelengths in the IR domain.Comment: 11 pages, 7 figures, and online material (2 tables). Submitted to A&A
in 2014 Januar
Endoderm Induction for Hepatic and Pancreatic Diff erentiation of ES Cells
Hepatic and pancreatic differentiation from ES cells is of great interest for the impact that this knowledge could have on the treatment of hepatic and diabetic patients. The liver and pancreas initially develop by budding from the embryonic endoderm. Thus, the development of the endoderm represents an important step and has an integral common role in initiating the early stages of pancreatic and liver development. We know that the development of hepatocytes and insulin-producing pancreatic beta-cells from ES cells represents the culmination of a complex developmental program. However, there has been recent progress in directing ES cells to endoderm and early-stage hepatic and pancreatic progenitor cells. We here discuss the role of the microenvironment, transcriptional factors and cytokines, which have been recognized as important molecules during the major steps of the development of the liver and pancreas. We also present the most recent advances and efforts taken to produce definitive endoderm-committed ES cells for the further differentiation of hepatocyte-like and insulinproducing cells. Recent progress in the search for new sources of hepatocytes and beta-cells has opened up several possibilities for the future of new perspectives for future of new prophylactic and therapeutic possibilities for liver diseases and diabetes.</p
Calibração multi-objetivo do Tank Model utilizando diversos algoritmos genéticos e critérios de parada
Calibration of hydrologic models estimates parameter values that cannot be measured and enable the rainfall-runoff processes simulation. Multi-objective evolutionary algorithms can make the calibration faster and more efficient through an iterative process. However, the standard stopping criterion used to stop the iterative process is to reach a pre-defined number of iterations defined by the modeller. Alternatively, the Ticona stopping criterion is based on the minimum number of iterations required to achieve a determined number of non-dominated solutions in the Pareto front, resulting in a reduction of the computational time without losing performance during the calibration processes. We evaluated the Ticona stopping criterion in the Tank Model calibration. The calibration processes were performed using data from two river basins, with three genetic algorithms and two objective functions. The Ticona stopping criterion required a computational time 27.4% to 44.1% lower than using the standard stopping criterion and were obtaining similar results in simulated streamflow time series and similar values of the best set of parameters.A calibração de modelos hidrológicos estima os valores de parâmetros que não podem ser mensurados e permite a simulação dos processos chuva-vazão. Os algoritmos evolucionários multi-objetivos podem tornam a calibração mais rápida e eficiente por meio de processos iterativos. Contudo, o critério de parada padrão usado para encerrar o processo iterativo é baseado em um número de iterações pré-definido pelo usuário. Como alternativa, o critério de parada Ticona é baseado no número mÃnimo de iterações requerido para alcançar um determinado número de soluções não-dominadas na Frente de Pareto, resultando em um menor tempo computacional sem perda de desempenho durante a calibração. Neste estudo, foi avaliado o uso do critério de parada Ticona na calibração do Tank Model. A calibração foi realizada em duas bacias hidrográficas, usando três algoritmos genéticos e duas funções-objetivo. Os resultados indicaram um tempo computacional 27,4% a 44,1% menor quando utilizado o critério de parada Ticona em comparação com o critério de parada padrão, ao mesmo tempo que foram obtidos resultados similares quanto aos valores dos parâmetros calibrados e à série temporal de vazão simulada
La Empresa Familiar- La sucesión generacional y su problemática. El Protocolo Familiar como posible solución.
Las empresas familiares son un elemento clave de la economÃa española, ya que suponen más de un 80% del total de empresas de nuestro paÃs y su aportación al PIB es muy elevada. Por ello, uno de sus objetivos estratégicos principales es que el proceso de sucesión generacional finalice de manera exitosa. El traslado del poder de una generación a otra generación es uno de las principales causas de muerte de las empresas familiares. La forma más eficaz de tener éxito en el proceso de sucesión, es planearla con suficiente antelación. La herramienta más utilizada para planificar la sucesión, además de otras cuestiones relevantes de la empresa familiar, es el Protocolo Familiar. El Protocolo Familiar es un instrumento muy flexible que puede ser adaptado a las necesidades de cada empresa. En este trabajo también estudiaremos otro de los principales problemas que sufren las empresas familiares, la tributación. <br /
Propiedades psicométricas de la escala adaptada de Procrastinación de Tuckman ATPS en estudiantes adultos de Lima Metropolitana, 2022
En el presente estudio se tuvo como objetivo analizar las propiedades psicométricas
de la Escala adaptada de Procrastinación de Tuckman (ATPS) en estudiantes adultos
de Lima Metropolitana. El trabajo fue de tipo aplicado, el diseño instrumental, cuya
base es el modelo cognitivo conductual; se contó con la participación de 500 sujetos
de los cuales 275 eran Universitarios y 225 Técnicos siendo 39 % hombres y 61 %
mujeres entre los 18 a 59 años estudiantes de tercio superior de Lima Metropolitana,
seleccionados a través del muestreo no probabilÃstico por conveniencia. Se realizó la
validez de contenido mediante el coeficiente V de Aiken= .96 en el que 10 jueces
expertos dieron conformidad; luego se analizó el IHC obteniendo como resultado que
los Ãtems 5 y 7 no ajustan y en el h2 los Ãtems 5, 7, 11, 12 y 14 no son aceptables; el
AFC del modelo teórico inicialmente no ajustaba, por lo que se reespecificó a 11 Ãtems
llegando a un ajuste adecuado X2 /gl= 2.72, RMSEA= .059, SRMR= .040, CFI= .997,
TLI=.996; después se hizo la correlación con el Inventario TAI-Estado (convergente)
(p= .000, r= .360) y la Escala EAA (divergente) (p= .000, r= -.200) siendo significativo
en ambas variables, además se realizó la confiabilidad por los coeficientes de (α= .84,
ω= .95) siendo aceptables; el análisis de equidad determinó que es invariante por sexo. En
conclusión, la escala cuenta con evidencias psicométricas aceptables
A 0535+26: an X-ray/Optical Tour
We compiled X-ray and Optical observations of the accreting X-ray binary
system A 0535+262 since its discovery in 1975, that will allow us to shed light
on the unpredictable behavior of this binary system. We present the data in
terms of the Be-disk interaction with the neutron star companion. In addition,
we show recent results from the continuous monitoring of this source by the
Gamma-ray Burst Monitor(GBM), on board the Fermi observatory, since its launch
in 2008 June 11.Comment: 4 pages, 5 figures, Conference proceeding of "Astrophysics of Neutron
Stars 2010 - a conference in honor of M. Ali Alpar", 2-6 August 2010, Cesme,
Izmir, Turke
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