Simulación del corazón izquierdo para aplicaciones en docencia e investigación

Un modelo es una descripción lógica de cómo un sistema funciona o como se comportan sus componentes. Las herramientas de la modelización dinámica facilitan mucho la construcción de los modelos. El objetivo de este proyecto es el de desarrollar y poner a prueba un modelo interactivo de la fisiología del sistema cardiocirculatorio (SCC) para el uso de estudiantes y otros interesados en la fisiología cardiovascular. El modelo es un modelo simple de cuatro componentes, y simula las siguientes variables y parámetros: a) variaciones del volumen aurícula izquierda (AI) y ventrículo izquierdo (VI); b) variaciones presión en la AI, VI y aorta (Ao); c) flujo a través de la válvula mitral (VM) y válvula aórtica (VAo), y d) imita el “efecto Windkessel” en la Ao. Se utilizó el entorno de modelización Extend el cual provee una estructura integrada para la construcción de modelos de simulación y el desarrollo de nuevas herramientas de simulación. El corazón derecho y la circulación pulmonar no son considerados. Los resultados de este modelo simulan las características generales del corazón izquierdo y de la circulación arterial, considerando distintas situaciones fisiológicas y patológicas.Área: Tecnología en Educación.Red de Universidades con Carreras en Informática (RedUNCI

Simulación del corazón izquierdo para aplicaciones en docencia e investigación

Un modelo es una descripción lógica de cómo un sistema funciona o cómo se comportan sus componentes. Las herramientas de la modelización dinámica facilitan mucho la construcción de los modelos. El objetivo de este artículo es mostrar el desarrollo y los resultados del funcionamiento de un modelo interactivo de la fisiología del sistema cardiocirculatorio para el uso de estudiantes y otros interesados en la fisiología cardiovascular. El sistema de simulación está compuesto por un modelo simple de cuatro componentes, y simula las siguientes variables y parámetros: a) variaciones del volumen aurícula izquierda (AI) y ventrículo izquierdo (VI); b) variaciones presión en AI, VI y aorta (Ao); c) flujo a través de válvula mitral (VM) y válvula aórtica (VAo), y d) reproduce el “efecto Windkessel” en Ao. Se utilizó el entorno de modelización Extend el cual provee una estructura integrada para la construcción de modelos de simulación y el desarrollo de nuevas herramientas de simulación. El corazón derecho y la circulación pulmonar no son considerados. Los resultados de este modelo simulan las características generales del corazón izquierdo y de la circulación arterial, considerando distintas situaciones fisiológicas y patológicas.Left heart simulation for applications in teaching and scientific research. A model is a logical description of how a system works or how their components behave. The tools of the dynamic modeling facilitate the construction of the models. The aim of this article is to show the development and results of the operation of an interactive model of the cardiocirculatory system physiology for the use of students and others interested in cardiovascular physiology. The model used is a simple model of four components, and simulates the following variables and parameters: a) volume variations of left atrial (LA) and left ventricle (LV); b) pressure variations in LA, LV and aorta (Ao); c) the flow across mitral (MV) and aortic valve (AoV), and d) imitates the "Windkessel effect" in Ao. The modeling environment "Extend" was used, which provides an integrated structure for the simulation models construction and the development of new simulations tools. The right heart and the pulmonary circulation are not considered. The model's results simulate the general characteristics of the left heart and of the arterial circulation, considering different physiological and pathological situations.Facultad de Informátic

Simulación del corazón izquierdo para aplicaciones en docencia e investigación

Un modelo es una descripción lógica de cómo un sistema funciona o cómo se comportan sus componentes. Las herramientas de la modelización dinámica facilitan mucho la construcción de los modelos. El objetivo de este artículo es mostrar el desarrollo y los resultados del funcionamiento de un modelo interactivo de la fisiología del sistema cardiocirculatorio para el uso de estudiantes y otros interesados en la fisiología cardiovascular. El sistema de simulación está compuesto por un modelo simple de cuatro componentes, y simula las siguientes variables y parámetros: a) variaciones del volumen aurícula izquierda (AI) y ventrículo izquierdo (VI); b) variaciones presión en AI, VI y aorta (Ao); c) flujo a través de válvula mitral (VM) y válvula aórtica (VAo), y d) reproduce el “efecto Windkessel” en Ao. Se utilizó el entorno de modelización Extend el cual provee una estructura integrada para la construcción de modelos de simulación y el desarrollo de nuevas herramientas de simulación. El corazón derecho y la circulación pulmonar no son considerados. Los resultados de este modelo simulan las características generales del corazón izquierdo y de la circulación arterial, considerando distintas situaciones fisiológicas y patológicas.Left heart simulation for applications in teaching and scientific research. A model is a logical description of how a system works or how their components behave. The tools of the dynamic modeling facilitate the construction of the models. The aim of this article is to show the development and results of the operation of an interactive model of the cardiocirculatory system physiology for the use of students and others interested in cardiovascular physiology. The model used is a simple model of four components, and simulates the following variables and parameters: a) volume variations of left atrial (LA) and left ventricle (LV); b) pressure variations in LA, LV and aorta (Ao); c) the flow across mitral (MV) and aortic valve (AoV), and d) imitates the "Windkessel effect" in Ao. The modeling environment "Extend" was used, which provides an integrated structure for the simulation models construction and the development of new simulations tools. The right heart and the pulmonary circulation are not considered. The model's results simulate the general characteristics of the left heart and of the arterial circulation, considering different physiological and pathological situations.Facultad de Informátic

26Al yields from rotating Wolf--Rayet star models

We present new $^{26}$Al stellar yields from rotating Wolf--Rayet stellar models which, at solar metallicity, well reproduce the observed properties of the Wolf-Rayet populations. These new yields are enhanced with respect to non--rotating models, even with respect to non--rotating models computed with enhanced mass loss rates. We briefly discuss some implications of the use of these new yields for estimating the global contribution of Wolf-Rayet stars to the quantity of $^{26}$Al now present in the Milky Way.Comment: 6 pages, 2 figures, to appear in New Astronomy Review

Nuclear activity and massive star formation in the low luminosity AGN NGC4303: Chandra X-ray observations

We present evidence of the co-existence of either an AGN or an ultraluminous X-ray source (ULX), together with a young super stellar cluster in the 3 central parsecs of NGC4303. The galaxy contains a low luminosity AGN and hosts a number of starburst regions in a circumnuclear spiral, as well as in the nucleus itself. A high spatial resolution Chandra image of this source reveals that the soft X-ray emission traces the ultraviolet nuclear spiral down to a core, which is unresolved both in soft and hard X-rays. The astrometry of the X-ray core coincides with the UV core within the Chandra positioning accuracy. The total X-ray luminosity of the core, 1.5*10^{39} erg/s, is similar to that from some LINERs or from the weakest Seyferts detected so far. The soft X-rays in both the core and the extended structure surrounding it can be well reproduced by evolutionary synthesis models (which include the emission expected from single stars, the hot diffuse gas, supernova remnants and binary systems), consistent with the properties of the young stellar clusters identified in the UV. The hard X-ray tail detected in the core spectrum, however, most likely requires the presence of an additional source. This additional source could either be a weak active nucleus black hole or an ultraluminous X-ray object. The implications of these results are discussed.Comment: 37 pages, 7 figures, ApJ accepte

Mouse Phenome Database

The Mouse Phenome Database (MPD; http://www.jax.org/phenome) is an open source, web-based repository of phenotypic and genotypic data on commonly used and genetically diverse inbred strains of mice and their derivatives. MPD is also a facility for query, analysis and in silico hypothesis testing. Currently MPD contains about 1400 phenotypic measurements contributed by research teams worldwide, including phenotypes relevant to human health such as cancer susceptibility, aging, obesity, susceptibility to infectious diseases, atherosclerosis, blood disorders and neurosensory disorders. Electronic access to centralized strain data enables investigators to select optimal strains for many systems-based research applications, including physiological studies, drug and toxicology testing, modeling disease processes and complex trait analysis. The ability to select strains for specific research applications by accessing existing phenotype data can bypass the need to (re)characterize strains, precluding major investments of time and resources. This functionality, in turn, accelerates research and leverages existing community resources. Since our last NAR reporting in 2007, MPD has added more community-contributed data covering more phenotypic domains and implemented several new tools and features, including a new interactive Tool Demo available through the MPD homepage (quick link: http://phenome.jax.org/phenome/trytools)

On the Optimization of Broad-Band Photometry for Galaxy Evolution Studies

We have derived the uncertainties to be expected in the derivation of galaxy physical properties (star formation history, age, metallicity, reddening) when comparing broad-band photometry to the predictions of evolutionary synthesis models. We have obtained synthetic colors for a large sample (9000) of artificial galaxies assuming different star formation histories, ages, metallicities, reddening values, and redshifts. The colors derived have been perturbed by adopting different observing errors, and compared back to the evolutionary synthesis models grouped in different sets. The comparison has been performed using a combination of Monte Carlo simulations, a Maximum Likelihood Estimator and Principal Component Analysis. After comparing the input and derived output values we have been able to compute the uncertainties and covariant degeneracies between the galaxy physical properties as function of (1) the set of observables available, (2) the observing errors, and (3) the galaxy properties themselves. In this work we have considered different sets of observables, some of them including the standard Johnson/Cousins (UBVRI) and Sloan Digital Sky Survey (SDSS) bands in the optical, the 2 Micron All Sky Survey (2MASS) bands in the near-infrared, and the Galaxy Evolution Explorer (GALEX) bands in the UV, at three different redshifts, z=0.0, 0.7, and 1.4. This study is intended to represent a basic tool for the design of future projects on galaxy evolution, allowing an estimate of the optimal band-pass combinations and signal-to-noise ratios required for a given scientific objective.Comment: 20 pages, 9 postscript figures, 3 tables, accepted for publication in A

Stellar Populations Found in the Central kpc of Four Luminous Compact Blue Galaxies at Intermediate Redshift

We investigate the star formation history of the central regions of four Luminous Compact Blue Galaxies (LCBGs). LCBGs are blue (B-V<0.6), compact (MU_B<21.5 mag arcsec^-2) galaxies with absolute magnitudes M_B brighter than -17.5. The LCBGs analyzed here are located at 0.436<z<0.525. They are among the most luminous (M_B < -20.5), blue (B-V < 0.4) and high surface brightness (MU_B < 19.0 mag arcsec^-2) of this population. The observational data used were obtained with the HST/STIS spectrograph, the HST/WF/PC-2 camera and the HST/NICMOS first camera. We find evidence for multiple stellar populations. One of them is identified as the ionizing population, and the other one corresponds to the underlying stellar generation. The estimated masses of the inferred populations are compatible with the dynamical masses, which are typically 2--10x 10^9 M_sun. Our models also indicate that the first episodes of star formation the presented LCBGs underwent happened between 5 and 7 Gyr ago. We compare the stellar populations found in LCBGs with the stellar populations present in bright, local HII galaxies, nearby spheroidal systems and Blue Compact Dwarf Galaxies. It turns out that the underlying stellar populations of LCBGs are similar yet bluer to those of local HII galaxies. It is also the case that the passive color evolution of the LCBGs could convert them into local Spheroidal galaxies if no further episode of star formation takes place. Our results help to impose constraints on evolutionary scenarios for the population of LCBGs found commonly at intermediate redshifts.Comment: 35 pages, 10 Figures. Accepted for publication in AJ. Compile with pdflatex. Contains png figure

Ultraviolet Properties of Primeval Galaxies: Theoretical Models from Stellar Population Synthesis

The ultraviolet luminosity evolution of star-forming galaxies is explored from the theoretical point of view, especially focusing on the theory of UV energetics in simple and composite stellar populations and its relationship to the star formation rate and other main evolutionary parameters. Galaxy emission below 3000 Angstroms directly correlates with actual star formation, not depending on the total mass of the system. A straightforward calibration is obtained, in this sense, from the theoretical models at 1600, 2000 and 2800 Angstroms, and a full comparison is carried out with IUE data and other balloon-borne observations for local galaxies. The claimed role of late-type systems as prevailing contributors to the cosmic UV background is reinforced by our results; at 2000 Angstroms Im irregulars are found in fact nearly four orders of magnitude brighter than ellipticals, per unit luminous mass. The role of dust absorption in the observation of high-redshift galaxies is assessed, comparing model output and observed spectral energy distribution of local galaxy samples. Similar to what we observe in our own galaxy, a quick evolution in the dust environment might be envisaged in primeval galaxies, with an increasing fraction of luminous matter that would escape the regions of harder and "clumpy" dust absorption on a timescale of some 10^7 yr, comparable with the lifetime of stars of 5-10 solar masses.Comment: 20 pages and 14 PS figures - To appear in the March issue of the Astronomical Journal. See http://www.merate.mi.astro.it/~eps/home.html for more info and model retrieva