Ultrastructural changes in chemically induced preneoplastic focal lesions in the rat liver: a stereological study

Ultrastructural changes were investigated and quantified, using a stereological approach, in early gamma-glutamyl transpeptidase (GGT)-positive focal lesions, induced in the rat liver by treatment with a single initiating dose of diethylnitrosamine (DENA) followed by promotion with phenobarbitone (PB) for 30 weeks. Within the extra-hepato cyte environment of focal tissue, the mean volume occupied by Ito cells was markedly decreased, whilst that occupied by endothelial and Kupffer cells was increased, when compared to uninvolved tissue from the same rat livers. The bile canalicull were dilated, but nosignificant differences in the mean volume occupkd by the sinusoidal and Disse spaces were noted. In focal hepatocytes there was a striking overproduction of lipid droplets and proliferation of smooth endoplasmic reticulum (sER). Whorls of concentrically arranged, parallel ER membranes were found only in the hepatocytes of preneoplastic foci, in association with the proliferated sER, and never in the surrounding, uninvolved tissue. The Increase In mean volume of the sER, lipid droplet and cytoplasmic matrix compartments, together with the appearance of whorls, were the major contributing factors to the marked hypertrophy seen in focal hepatocytes. The mean volume of the rough endoplasmic reticulum, mitochondrial, lysosomal, peroxisomal and nuclear compartments per hepatocyte also Increased, but contributed to a lesser extent to the cellular hypertrophy. It is speculated that whorls may be structural adaptations, resulting from a possible alteration in the normalfeedback control of cholesterol synthesis, for the production of sterols and the biogenesis of sER in eosinophilic-type focal cells. The significance of changes observed in focal tissue, and the high biological variation noted between foci, is discussed in relation to the hepatocarcinogenic proces

Exclusion of Class III malocclusion candidate loci in Brazilian families

The role played by genetic components in the etiology of the Class III phenotype, a class of dental malocclusion, is not yet understood. Regions that may be related to the development of Class III malocclusion have been suggested previously. The aim of this study was to search for genetic linkage with 6 microsatellite markers (D1S234, D4S3038, D6S1689, D7S503, D10S1483, and D19S566), near previously proposed candidate regions for Class III. We performed a two-point parametric linkage analysis for 42 affected individuals from 10 Brazilian families with a positive Class III malocclusion segregation. Analysis of our data indicated that there was no evidence for linkage of any of the 6 microsatellite markers to a Class III locus at = zero, with data supporting exclusion for 5 of the 6 markers evaluated. The present work reinforces that Class III is likely to demonstrate locus heterogeneity, and there is a dependency of the genetic background of the population in linkage studies

Sensitivity of conservative pollutants estimation using ISCST3 to input parameters for a case of study

[ES] El presente documento describe un proceso de análisis realizado sobre el modelo gaussiano de dispersión de contaminantes atmosféricos ISCST3 aplicado en un área densamente poblada, el Instituto Superior Politécnico José Antonio Echeverría (CUJAE) ubicado en la Habana. Para la simulación numérica se realizó un inventario de fuentes y de emisiones de contaminantes atmosféricos en la zona, para estimar la concentración del contaminante conservativo, en este caso dióxido de azufre. El objetivo es mostrar la sensibilidad de esta simulación numérica con la variación en la entrada de varios parámetros: albedo medio, razón de Bowen, rugosidad de la superficie y velocidad del viento. Una vez obtenidos los resultados se analiza la influencia de las variaciones en la entrada de dichos parámetros sobre la concentración del contaminante estudiado. Concluyendo que la velocidad del viento es el parámetro al que el modelo es más sensible y presenta la menor sensibilidad a los cambios en la entrada del albedo. El receptor menos afectado en los valores de concentración estimados para 24 horas es el receptor 2, ubicado en el centro de la malla y correspondiente al campus universitario de la CUJAE. Mientras que para valores horarios los menos sensibles son los receptores 1 y 3.[EN] This paper describes a process of analysis of the Gaussian model ISCST3 of air pollutants dispersión applied in a densely populated area, the Higher Polytechnic Institute José Antonio Echeverría (CUJAE) in Havana. For the numerical simulation was carried out a sources and emissions inventory of air pollutants in the área, to estímate the concentration of the conservative pollutant, in this case sulfur dioxide. The objective is to show the sensitivity of numerical simulation with variation in the input of several parameters: average albedo, Bowen ratio, surface roughness and wind speed. After obtaining the results, the influence of variatíons in these parameters input and contaminant concentration studied is analyzed. Concluding that the wind speed is the parameter to which the model is more sensitive and has the lowest sensitivity to changes in albedo input. The least affected receptor concentration values estimated for 24 hours is the number 2, located in the center of the screen and land in the campus CUJAE. While for hourly values, receptors 1 and 3 are less sensitive.Los autores agradecen al proyecto de Doctorado auricular en su dimensión ambiental existente entre el Instituto Superior Politécnico José Antonio Echeverría (CUJAE) y la Universidad Politécnica de Valencia que permitió en el marco del mismo la realización de este trabajo. Además de nuestra gratitud a otras instituciones que facilitaron los datos y medios para la investigación como son: Dirección Provincial de Salud Pública de ciudad de La Habana, Cuba energía perteneciente al Ministerio de Ciencia Tecnología y Medio Ambiente y a la Oficina de Acción Internacional (OIA) de la Universidad Politécnica de Valencia.González-Cruz, M.; Pire-Rivas, S.; López Jiménez, PA. (2012). Sensibilidad del modelo ISCST3 en la estimación de contaminantes conservativos: Caso de estudio. REVISTA MEXICANA DE INGENIERÍA QUÍMICA. 11(2):287-298. http://hdl.handle.net/10251/150423S28729811

Simulating spin systems on IANUS, an FPGA-based computer

We describe the hardwired implementation of algorithms for Monte Carlo simulations of a large class of spin models. We have implemented these algorithms as VHDL codes and we have mapped them onto a dedicated processor based on a large FPGA device. The measured performance on one such processor is comparable to O(100) carefully programmed high-end PCs: it turns out to be even better for some selected spin models. We describe here codes that we are currently executing on the IANUS massively parallel FPGA-based system.Comment: 19 pages, 8 figures; submitted to Computer Physics Communication

Nature of the spin-glass phase at experimental length scales

We present a massive equilibrium simulation of the three-dimensional Ising spin glass at low temperatures. The Janus special-purpose computer has allowed us to equilibrate, using parallel tempering, L=32 lattices down to T=0.64 Tc. We demonstrate the relevance of equilibrium finite-size simulations to understand experimental non-equilibrium spin glasses in the thermodynamical limit by establishing a time-length dictionary. We conclude that non-equilibrium experiments performed on a time scale of one hour can be matched with equilibrium results on L=110 lattices. A detailed investigation of the probability distribution functions of the spin and link overlap, as well as of their correlation functions, shows that Replica Symmetry Breaking is the appropriate theoretical framework for the physically relevant length scales. Besides, we improve over existing methodologies to ensure equilibration in parallel tempering simulations.Comment: 48 pages, 19 postscript figures, 9 tables. Version accepted for publication in the Journal of Statistical Mechanic

Janus II: a new generation application-driven computer for spin-system simulations

This paper describes the architecture, the development and the implementation of Janus II, a new generation application-driven number cruncher optimized for Monte Carlo simulations of spin systems (mainly spin glasses). This domain of computational physics is a recognized grand challenge of high-performance computing: the resources necessary to study in detail theoretical models that can make contact with experimental data are by far beyond those available using commodity computer systems. On the other hand, several specific features of the associated algorithms suggest that unconventional computer architectures, which can be implemented with available electronics technologies, may lead to order of magnitude increases in performance, reducing to acceptable values on human scales the time needed to carry out simulation campaigns that would take centuries on commercially available machines. Janus II is one such machine, recently developed and commissioned, that builds upon and improves on the successful JANUS machine, which has been used for physics since 2008 and is still in operation today. This paper describes in detail the motivations behind the project, the computational requirements, the architecture and the implementation of this new machine and compares its expected performances with those of currently available commercial systems.Comment: 28 pages, 6 figure

The hologram and its utilization as a physics teaching tool for physics teaching in engineering courses

With the emergence and development of the white-light holograms, new possibilities were created for its utilization as a teaching tool due to the characteristic of producing a three-dimensional image which constitutes an optical duplicate of the object. In this work the distinctive aspects of the hologram are described and its utilization is analyzed in engineering courses, through the design and construction of a Didactic Exhibition of Holography.Con el surgimiento de los hologramas reconstruibles con luz blanca y su desarrollo posterior, se abrieron grandes posibilidades para su utilización como medio de enseñanza por la característica de producir una imagen tridimensional que constituye un duplicado óptico de un objeto. En el trabajo se describen las características distintivas del holograma como un medio de enseñanza de la física y se analiza su utilización en carreras de ingeniería, mediante la fundamentación, el diseño y construcción de una Exposición Didáctica de Holografía creada para este propósito.1401.11401.1

Generalized Holographic Dark Energy Model

In this paper, the model of holographic Chaplygin gas has been extended to two general cases: first is the case of modified variable Chaplygin gas and secondly of the viscous generalized Chaplygin gas. The dynamics of the model are expressed by the use of scalar fields and the scalar potentials.Comment: 12 pages, to appear in Eur. Phys. J.

Temperature chaos is present in off-equilibrium spin-glass dynamics

Experiments featuring non-equilibrium glassy dynamics under temperature changes still await interpretation. There is a widespread feeling that temperature chaos (an extreme sensitivity of the glass to temperature changes) should play a major role but, up to now, this phenomenon has been investigated solely under equilibrium conditions. In fact, the very existence of a chaotic effect in the non-equilibrium dynamics is yet to be established. In this article, we tackle this problem through a large simulation of the 3D Edwards-Anderson model, carried out on the Janus II supercomputer. We find a dynamic effect that closely parallels equilibrium temperature chaos. This dynamic temperature-chaos effect is spatially heterogeneous to a large degree and turns out to be controlled by the spin-glass coherence length ¿. Indeed, an emerging length-scale ¿* rules the crossover from weak (at ¿ « ¿*) to strong chaos (¿ » ¿*). Extrapolations of ¿* to relevant experimental conditions are provided. © 2021, The Author(s)