124 research outputs found
Groups with dense nearly normal subgroups
This paper studies groups in which the set of nearly normal subgroups is dense in the lattice of all subgroups. In particular it is provided a characterization for locally finite groups and non periodic groups
Animation, Simulation, and Control of Soft Characters using Layered Representations and Simplified Physics-based Methods
Realistic behavior of computer generated characters is key to bringing virtual environments, computer games, and other interactive applications to life. The plausibility of a virtual scene is strongly influenced by the way objects move around and interact with each other. Traditionally, actions are limited to motion capture driven or pre-scripted motion of the characters. Physics enhance the sense of realism: physical simulation is required to make objects act as expected in real life. To make gaming and virtual environments truly immersive,it is crucial to simulate the response of characters to collisions and to produce secondary effects such as skin wrinkling and muscle bulging. Unfortunately, existing techniques cannot generally achieve these effects in real time, do not address the coupled response of a character's skeleton and skin to collisions nor do they support artistic control. In this dissertation, I present interactive algorithms that enable physical simulation of deformable characters with high surface detail and support for intuitive deformation control. I propose a novel unified framework for real-time modeling of soft objects with skeletal deformations and surface deformation due to contact, and their interplay for object surfaces with up to tens of thousands of degrees of freedom.I make use of layered models to reduce computational complexity. I introduce dynamic deformation textures, which map three dimensional deformations in the deformable skin layer to a two dimensional domain for extremely efficient parallel computation of the dynamic elasticity equations and optimized hierarchical collision detection. I also enhance layered models with responsive contact handling, to support the interplay between skeletal motion and surface contact and the resulting two-way coupling effects. Finally, I present dynamic morph targets, which enable intuitive control of dynamic skin deformations at run-time by simply sculpting pose-specific surface shapes. The resulting framework enables real-time and directable simulation of soft articulated characters with frictional contact response, capturing the interplay between skeletal dynamics and complex,non-linear skin deformations
Equatorial Lensing in the Balasin-Grumiller Galaxy Model
The Balasin-Grumiller model has been the first model employed as an attempt
towards providing a fully general relativistic description of the dynamics of a
disc galaxy. In this paper, we compute the equatorial gravitational lensing
observables of the model. Indeed, our purpose is to investigate the role that
gravitational lensing plays as an observable in distinguishing between the
state-of-the-art galaxy models and the fully general relativistic ones, with
the latter stressing the role of frame-dragging and hence conceivably pointing
to a possible re-weighting of the dark matter content of disc galaxies. We
obtain for the Balasin-Grumiller model the exact formula for the bending angle
of light and we provide a corresponding estimate for the time delay between
images in the equatorial plane. For a reasonable choice for the values of the
parameters of the solution (bulge and scale radiuses, and average rotational
star speeds), the values that we obtain for the bending angle are in agreement
with those observed for typical disc galaxies. On the other hand, the
calculated time delay, which is directly tied to the frame-dragging generated
by the angular momentum of the galaxy, turns out to be some orders of magnitude
larger than the ones measured for the class of galaxies that the
Balasin-Grumiller model would claim to describe. We believe this abnormal
discrepancy to be due to the very nature of the Balasin-Grumiller model.
Namely, it being rigidly rotating, hence providing an unphysical amount of
frame-dragging. Therefore, we conclude that, in spite of its simplicity and its
unquestionable didactical value, the Balasin-Grumiller model is far too crude
to provide an instrument for a reliable general relativistic description of a
disc galaxy and that further work in the fully general relativistic modelling
of galaxies is required to reach a satisfactory stage.Comment: 19 pages and 6 figure
Hepatitis autoinmune en pediatrĂa
ResumenLa hepatitis autoinmune es una enfermedad de etiología desconocida que implica un proceso infl amatorio severo del hígado con progresión a la cirrosis e insufi ciencia hepática. El presente artículo presenta las aspectos relevantes de la enfermedad, así como la experiencia de la autora en el Hospital de Niños “R.Gutiérrez”, Buenos Aires, Argentina.[Galoppo MC. Hepatitis autoinmune en pediatría. MedUNAB 2005; 8 (1 Supl 1):S43-44]Palabras clave: Hepatitis, hepatitis autoinmune
Serum apoptosis markers related to liver damage in chronic hepatitis C: sFas as a marker of advanced fibrosis in children and adults while M30 of severe steatosis only in children
Background: Liver biopsy represents the gold standard for evaluating damage and progression in patients with chronic hepatitis C (CHC); however, developing noninvasive tests that can predict liver injury represents a growing medical need. Considering that hepatocyte apoptosis plays a role in CHC pathogenesis; the aim of our study was to evaluate the presence of different apoptosis markers that correlate with liver injury in a cohort of pediatric and adult patients with CHC. Methods: Liver biopsies and concomitant serum samples from 22 pediatric and 22 adult patients with CHC were analyzed. Histological parameters were evaluated. In serum samples soluble Fas (sFas), caspase activity and caspase-generated neoepitope of the CK-18 proteolytic fragment (M30) were measured. Results: sFas was associated with fibrosis severity in pediatric (significant fibrosis p=0.03, advanced fibrosis p=0.01) and adult patients (advanced fibrosis p=0.02). M30 levels were elevated in pediatric patients with severe steatosis (p=0.01) while in adults no relation with any histological variable was observed. Caspase activity levels were higher in pediatric samples with significant fibrosis (p=0.03) and they were associated with hepatitis severity (p=0.04) in adult patients. The diagnostic accuracy evaluation demonstrated only a good performance for sFas to evaluate advanced fibrosis both in children (AUROC: 0.812) and adults (AUROC: 0.800) as well as for M30 to determine steatosis severity in children (AUROC: 0.833). Conclusions: Serum sFas could be considered a possible marker of advanced fibrosis both in pediatric and adult patient with CHC as well as M30 might be a good predictor of steatosis severity in children.Fil: Valva, Pamela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez". Servicio de AnatomĂa PatolĂłgica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Casciato, Paola. Hospital Italiano; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Lezama, Carol. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez"; ArgentinaFil: Galoppo, Marcela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez"; ArgentinaFil: Gadano, Adrián Carlos. Hospital Italiano; ArgentinaFil: Galdame, Omar. Hospital Italiano; ArgentinaFil: Galoppo, MarĂa Cristina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez"; ArgentinaFil: Mullen, Eduardo. Hospital Italiano; ArgentinaFil: de Matteo, Elena NoemĂ. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez". Servicio de AnatomĂa PatolĂłgica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Preciado, MarĂa Victoria. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo GutiĂ©rrez". Servicio de AnatomĂa PatolĂłgica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Hepatitis b. Historia natural. Manejo del niño portador asintomático
La hepatitis B es aĂşn un problema de salud pĂşblica a nivel mundial. SegĂşn datos del CDC el 42% de las hepatitis B crĂłnicas del adulto han sido adquiridas durante la infancia. La historia natural de la infecciĂłn
crónica por el VHB se caracteriza por tres fases: inicial de tolerancia inmune al virus; de “clearence” inmune de
variable duración, y de remisión. Durante la infancia y sobre todo la adolescencia más del 80% de los pacientes con VHB seroconvierten a antiHBe. La historia natural
de la infecciĂłn crĂłnica actualmente puede ser
modificada por la indicaciĂłn del tratamiento apropiado el que, en un porcentaje de pacientes, evita la progresiĂłn de la enfermedad y sus secuelas
Enseñanza de la Matemática utilizando TICs en el primer año de las Carreras de IngenierĂa de la Facultad de Ciencias Exactas, FĂsicas y Naturales de la UNC
Fil: Azpilicueta, Jorge. Universidad Nacional de CĂłrdoba; Argentina.Fil: Galoppo, JosĂ©. Universidad Nacional de CĂłrdoba; Argentina.Fil: Ledesma, Alicia. Universidad Nacional de CĂłrdoba; Argentina.El objetivo de este estudio es realizar una valoraciĂłn cuali-cuantitativa de una experiencia positiva de aprendizaje virtual en la enseñanza de la matemática en las materias de primer año IntroducciĂłn a la Matemática y Análisis Matemático I de las carreras de IngenierĂa durante los años 2012-2013. Los cursos están diseñados para el desarrollo de habilidades de uso del lenguaje lĂłgico, a travĂ©s de actividades matemáticas especĂficas para la acciĂłn, las que facilitan su comprensiĂłn y la aprobaciĂłn del curso. Se expone la estructura de los cursos y las interacciones de los estudiantes como valoraciones cualitativas, y los porcentajes de aprobaciĂłn como valoraciones cuantitativas. La modalidad virtual como apoyo al proceso de enseñanza-aprendizaje de las Matemáticas se ve favorecida por el diseño tecno-pedagĂłgico del aula virtual y por el mayor rendimiento acadĂ©mico de los alumnos.Fil: Azpilicueta, Jorge. Universidad Nacional de CĂłrdoba; Argentina.Fil: Galoppo, JosĂ©. Universidad Nacional de CĂłrdoba; Argentina.Fil: Ledesma, Alicia. Universidad Nacional de CĂłrdoba; Argentina.Otras Matemática
Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species
Agricultural pesticides represent a significant class of endocrine-disrupting chemicals (EDCs) to which non-target organisms around the world are constantly exposed. Laboratory studies have found strong evidence showing the endocrine-disruptive potential of these pesticides at environmentally relevant exposure levels. Since the field of endocrine disruption continues to grow in richness and complexity, this review aims to provide an update on the effects of two agricultural pesticides that act as EDCs: atrazine and endosulfan. We will focus mainly on the effects on crocodilians due to their worldwide occurrence in tropical and sub-tropical wetland ecosystems and their ecological and physiological features, which render them vulnerable to exposure to pesticides with endocrine-disrupting action at all life stages. The results here reviewed provide important insights into the effects of hormonally active agricultural pesticides at cellular, tissue, and organ levels in the reproductive system of crocodiles. A better understanding of the effects of exposure to environmentally relevant doses of EDCs on the reproductive system of crocodilians will contribute to protect and improve the health of both wildlife species and humans.Fil: Tavalieri, Yamil Ezequiel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Galoppo, Germán Hugo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Canesini, Guillermina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Luque, Enrique Hugo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Muñoz de Toro, Monica Milagros. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentin
Characterisation of a silicon photomultiplier based oncological brachytherapy fibre dosimeter
Source localisation and real-time dose verification are at the forefront of medical research in brachytherapy, an oncological radiotherapy procedure based on radioactive sources implanted in the patient body. The ORIGIN project aims to respond to this medical community's need by targeting the development of a multi-point dose mapping system based on fibre sensors integrating a small volume of scintillating material into the tip and interfaced with silicon photomultipliers operated in counting mode. In this paper, a novel method for the selection of the optimal silicon photomultipliers to be used is presented, as well as a laboratory characterisation based on dosimetric figures of merit. More specifically, a technique exploiting the optical cross-talk to maintain the detector linearity in high-rate conditions is demonstrated. Lastly, it is shown that the ORIGIN system complies with the TG43-U1 protocol in high and low dose rate pre-clinical trials with actual brachytherapy sources, an essential requirement for assessing the proposed system as a dosimeter and comparing the performance of the system prototype against the ORIGIN project specifications
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