An Introduction to Algebraic Geometry codes

We present an introduction to the theory of algebraic geometry codes. Starting from evaluation codes and codes from order and weight functions, special attention is given to one-point codes and, in particular, to the family of Castle codes

Constraining Omega using weak gravitational lensing by clusters

The morphology of galaxy clusters reflects the epoch at which they formed and hence depends on the value of the mean cosmological density, Omega. Recent studies have shown that the distribution of dark matter in clusters can be mapped from analysis of the small distortions in the shapes of background galaxies induced by weak gravitational lensing in the cluster potential. We construct new statistics to quantify the morphology of clusters which are insensitive to limitations in the mass reconstruction procedure. By simulating weak gravitational lensing in artificial clusters grown in numerical simulations of the formation of clusters in three different cosmologies, we obtain distributions of a quadrupole statistic which measures global deviations from spherical symmetry in a cluster. These distributions are very sensitive to the value of Omega_0 and, as a result, lensing observations of a small number of clusters should be sufficient to place broad constraints on Omega_{0} and certainly to distinguish between the extreme values of 0.2 and 1.Comment: Submitted to MNRAS. Compressed postscript also available at ftp://star-ftp.dur.ac.uk/pub/preprints/wcf2.ps.g

El proceso cognitivo de la visualización en los estudiantes de nivel superior mediante el uso de software dinámico (Cabri) en la resolución de problemas geométricos

¿Qué ventajas o limitaciones ofrece a los estudiantes el empleo de herramientas tecnológicas en el aprendizaje de las matemáticas? ¿Qué tipo de representaciones utilizan los alumnos al resolver problemas a través del empleo de alguna herramienta tecnológica? ¿Qué tipo de preguntas o conjeturas formulan los estudiantes en la resolución de problemas con la ayuda de la tecnología? Estas son algunas preguntas que aparecen en la agenda de investigación relacionadas con el uso de la tecnología en el aprendizaje de las matemáticas. Así, investigar y documentar los procesos cognitivos que muestren los alumnos mientras resuelven problemas o actividades con apoyo de la tecnología, como el software dinámico, resulta una tarea que puede ayudar a identificar y analizar las ventajas y/o desventajas que el uso de dichas herramientas representa en el aprendizaje de las matemáticas. El empleo de herramientas tecnológicas en la resolución de problemas requiere amplia investigación acerca de los diferentes usos en los procesos de aprendizaje de los estudiantes. En este sentido, Steen mencionan que “los resultados producidos por las computadoras y sus aplicaciones están cambiando profundamente la forma de desarrollar las matemáticas, la forma de enseñarlas, así como la forma de aprenderlas” (situado en Santos, 1997, p.10). Un aspecto relevante en el empleo de la tecnología es el tipo de demostraciones o pruebas que pueden presentar los estudiantes; así, resulta necesario identificar los aspectos que se favorecen al utilizar software dinámico en actividades en la que los alumnos tengan oportunidad de descubrir relaciones, plantear conjeturas, generalizar resultados y utilizar argumentos que justifiquen sus soluciones o resultados. La resolución de problemas que contemplen actividades que estimulen la experimentación, el descubrimiento, el planteamiento de conjeturas y la explicación, en ambientes de uso de formas de razonamiento que les permita explicar y justificar distintas relaciones matemáticas. Así, es importante analizar el impacto o relevancia del uso del software. Dinámico en ambientes de resolución de problemas donde los estudiantes consistentemente, exhiban sus formas de razonamiento. Santos y Moreno (2001) resaltan que el uso sistemático de la tecnología con el tiempo se va convirtiendo en una herramienta poderosa para que los estudiantes le den sentido a la información, que realicen conjeturas y que examinen diferentes estrategias en la resolución de problemas. El objetivo de este estudio es documentar lo que muestra estudiantes de nivel medio superior al trabajar un conjunto de actividades con la ayuda del software dinámico. En particular, interesa analizar el tipo de representaciones, conjeturas y argumentos que utilizan los alumnos durante la solución de esas tareas

Creatividad en la resolución de problemas

En este trabajo de investigación se propone, como un factor con el que este autor está altamente motivado: hacer una descripción coherente del diseño de un modelo y un procedimiento didáctico mediante el uso de software dinámico para el perfeccionamiento de la enseñanza aprendizaje de la geometría en Ingenierías

B.O.P.T. Biologically Oriented Preparation Technique (Técnica de Preparação Biologicamente Orientada)

A reabilitação através de prótese fixa sobre dentes , é amplamente utilizada na reabilitação estética e funcional. No entanto, a recessão gengival é uma das mais comuns complicações inerentes a este tipo de restauração, expondo a linha de transição entre a margem protética e o dente natural. Tradicionalmente é executada uma linha de acabamento no preparo onde assenta a prótese (infra ou supragengival). A morfologia deste pilar desempenha um dos factores mais importantes para uma estabilidade da margem gengival, tendo isto em linha conta a técnica BOPT apresenta um novo realce, mediante o desenvolvimento de um perfil protético numa zona de acabamento sem margem definida no preparo. A BOPT é um protocolo de restauração que visa imitar os dentes naturais, para que a anatomia dentária seja transferida para a restauração protética definitiva. Desta forma, uma interação livre com a gengiva pode ocorrer de modo que se adapte, se forme e que assente em torno das novas formas e perfis. Comparando com técnicas convencionais, a BOPT tem demonstrado promover uma estabilidade dos tecidos a médio e longo prazo, adaptando-se por si mesmos e de forma natural ao preparo e à restauração.Rehabilitation through fixed prosthesis on teeth is widely used in aesthetic and functional rehabilitation. However, one of the complications inherent to this type of restoration is the gingival recession, exposing the transition line between the prosthetic margin and the natural tooth. Traditionally a finishing line is executed where the prosthesis (infra or supragingival) rests. The morphology of this abutment plays an important role in the stability of the gingival margin, therefor the BOPT presents a new enhancement by developing a prosthetic profile in a finishing zone without defined margin of the preparation.. BOPT is a restoration protocol that aims to imitate the natural teeth, so that the dental anatomy is transferred to the final prosthetic restoration. In this way, a free interaction with the gum can occur so that it fits, forms and rests around new shapes and profiles. Compared with conventional techniques, BOPT has been shown to promote tissue stability in the medium and long term, adapting itself and naturally to the preparation and restoration

A new view on the ISM of galaxies: far-infrared and submillimetre spectroscopy with Herschel

The FIR/submm window is amongst the least explored spectral regions of the electromagnetic spectrum. It is, however, a key to study the general properties of the interstellar medium of galaxies, as it contains important spectral line diagnostics from the neutral, ionized and molecular ISM. The Herschel Space Observatory, successfully launched on 14 May 2009, is the first observatory to cover the entire FIR/submm range between 57 and 672 mum. We discuss the main results from the ISO era on FIR spectroscopy of galaxies and the enormous science potential of the Herschel mission through a presentation of its spectroscopic extragalactic key programs.Comment: 10 pages, 4 figures, accepted for publication in New Astronomy Review

Neuregulin-1 attenuates experimental cerebral malaria (ECM) pathogenesis by regulating ErbB4/AKT/STAT3 signaling.

BACKGROUND:Human cerebral malaria (HCM) is a severe form of malaria characterized by sequestration of infected erythrocytes (IRBCs) in brain microvessels, increased levels of circulating free heme and pro-inflammatory cytokines and chemokines, brain swelling, vascular dysfunction, coma, and increased mortality. Neuregulin-1β (NRG-1) encoded by the gene NRG1, is a member of a family of polypeptide growth factors required for normal development of the nervous system and the heart. Utilizing an experimental cerebral malaria (ECM) model (Plasmodium berghei ANKA in C57BL/6), we reported that NRG-1 played a cytoprotective role in ECM and that circulating levels were inversely correlated with ECM severity. Intravenous infusion of NRG-1 reduced ECM mortality in mice by promoting a robust anti-inflammatory response coupled with reduction in accumulation of IRBCs in microvessels and reduced tissue damage. METHODS:In the current study, we examined how NRG-1 treatment attenuates pathogenesis and mortality associated with ECM. We examined whether NRG-1 protects against CXCL10- and heme-induced apoptosis using human brain microvascular endothelial (hCMEC/D3) cells and M059K neuroglial cells. hCMEC/D3 cells grown in a monolayer and a co-culture system with 30 μM heme and NRG-1 (100 ng/ml) were used to examine the role of NRG-1 on blood brain barrier (BBB) integrity. Using the in vivo ECM model, we examined whether the reduction of mortality was associated with the activation of ErbB4 and AKT and inactivation of STAT3 signaling pathways. For data analysis, unpaired t test or one-way ANOVA with Dunnett's or Bonferroni's post test was applied. RESULTS:We determined that NRG-1 protects against cell death/apoptosis of human brain microvascular endothelial cells and neroglial cells, the two major components of BBB. NRG-1 treatment improved heme-induced disruption of the in vitro BBB model consisting of hCMEC/D3 and human M059K cells. In the ECM murine model, NRG-1 treatment stimulated ErbB4 phosphorylation (pErbB4) followed by activation of AKT and inactivation of STAT3, which attenuated ECM mortality. CONCLUSIONS:Our results indicate a potential pathway by which NRG-1 treatment maintains BBB integrity in vitro, attenuates ECM-induced tissue injury, and reduces mortality. Furthermore, we postulate that augmenting NRG-1 during ECM therapy may be an effective adjunctive therapy to reduce CNS tissue injury and potentially increase the effectiveness of current anti-malaria therapy against human cerebral malaria (HCM)

Bicategorías de Tangles y la cohomología de Khovanov

La Cohomología de Khovanov es un invariante topológico de nudos el cual relaciona la categoría de uno-variedades cerradas planas y sus cobordismos, con la categoría de módulos sobre un anillo R, donde los morfismos son productos y coproductos definidos sobre el un Rmódulo A. Esta relación se hace a través de un funtor que se denomina una Topological Quantum Field Theory (TQFT)