Interacting Particles and Strings in Path and Surface Representations

Non-relativistic charged particles and strings coupled with abelian gauge fields are quantized in a geometric representation that generalizes the Loop Representation. We consider three models: the string in self-interaction through a Kalb-Ramond field in four dimensions, the topological interaction of two particles due to a BF term in 2+1 dimensions, and the string-particle interaction mediated by a BF term in 3+1 dimensions. In the first case one finds that a consistent "surface-representation" can be built provided that the coupling constant is quantized. The geometrical setting that arises corresponds to a generalized version of the Faraday's lines picture: quantum states are labeled by the shape of the string, from which emanate "Faraday`s surfaces". In the other models, the topological interaction can also be described by geometrical means. It is shown that the open-path (or open-surface) dependence carried by the wave functional in these models can be eliminated through an unitary transformation, except by a remaining dependence on the boundary of the path (or surface). These feature is closely related to the presence of anomalous statistics in the 2+1 model, and to a generalized "anyonic behavior" of the string in the other case.Comment: RevTeX 4, 28 page

Loop representation of charged particles interacting with Maxwell and Chern-Simons fields

The loop representation formulation of non-relativistic particles coupled with abelian gauge fields is studied. Both Maxwell and Chern-Simons interactions are separately considered. It is found that the loop-space formulations of these models share significant similarities, although in the Chern-Simons case there exists an unitary transformation that allows to remove the degrees of freedom associated with the paths. The existence of this transformation, which allows to make contact with the anyonic interpretation of the model, is subjected to the fact that the charge of the particles be quantized. On the other hand, in the Maxwell case, we find that charge quantization is necessary in order to the geometric representation be consistent.Comment: 6 pages, improved versio

Enhanced error estimator based on a nearly equilibrated moving least squares recovery technique for FEM and XFEM

In this paper a new technique aimed to obtain accurate estimates of the error in energy norm using a moving least squares (MLS) recovery-based procedure is presented. We explore the capabilities of a recovery technique based on an enhanced MLS fitting, which directly provides continuous interpolated fields, to obtain estimates of the error in energy norm as an alternative to the superconvergent patch recovery (SPR). Boundary equilibrium is enforced using a nearest point approach that modifies the MLS functional. Lagrange multipliers are used to impose a nearly exact satisfaction of the internal equilibrium equation. The numerical results show the high accuracy of the proposed error estimator

Discovery of the Optical Transient of the Gamma Ray Burst 990308

The optical transient of the faint Gamma Ray Burst 990308 was detected by the QUEST camera on the Venezuelan 1-m Schmidt telescope starting 3.28 hours after the burst. Our photometry gives $V = 18.32 \pm 0.07$, $R = 18.14 \pm 0.06$, $B = 18.65 \pm 0.23$, and $R = 18.22 \pm 0.05$ for times ranging from 3.28 to 3.47 hours after the burst. The colors correspond to a spectral slope of close to $f_{\nu} \propto \nu^{1/3}$. Within the standard synchrotron fireball model, this requires that the external medium be less dense than $10^{4} cm^{-3}$, the electrons contain $> 20$ of the shock energy, and the magnetic field energy must be less than 24% of the energy in the electrons for normal interstellar or circumstellar densities. We also report upper limits of $V > 12.0$ at 132 s (with LOTIS), $V > 13.4$ from 132-1029s (with LOTIS), $V > 15.3$ at 28.2 min (with Super-LOTIS), and a 8.5 GHz flux of $< 114 \mu Jy$ at 110 days (with the Very Large Array). WIYN 3.5-m and Keck 10-m telescopes reveal this location to be empty of any host galaxy to $R > 25.7$ and $K > 23.3$. The lack of a host galaxy likely implies that it is either substantially subluminous or more distant than a red shift of $\sim 1.2$.Comment: ApJ Lett submitted, 5 pages, 2 figures, no space for 12 coauthor

Gaining access to agency and structure in industrial marketing theory : a critical pluralist approach.

This article is concerned with gaining greater insight into the interplay between agency and structure in industrial marketing (IM) scholarship. The article’s intent is to embed Midgley’s notion of critical pluralism within this endeavour. The article commends the movement towards increased deployment of critical realism, but cautions against the dangers of creating further atomism in marketing theory by generating another paradigm of thought with strongly defended boundaries, impervious to outside influence. The article advances a case for critical pluralism within IM scholarship and offers a three-dimensional (theoretical, methodological and methodical) framework to aid this. The discussion demonstrates how critical pluralism can be deployed to gain insights into agency and structure using a number of ‘integrative’ theoretical perspectives

Efecto de la fermentación sobre el contenido de purinas en cacao Criollo e Hibrido (Theobroma cacao L.) del Sur del Lago de Maracaibo

Con la finalidad de evaluar el efecto de la fermentación sobre el contenido de purinas en cacao Criollo e Híbrido del Sur del Lago de Maracaibo, se realizó un ensayo, en el cual las almendras fueron fermentadas por cuatro días, luego secadas al sol, descascarilladas, congeladas y molidas. Las purinas se determinaron por cromatografía líquida en una columna C18 en fase reversa y una solución al 20% v/v metanol: agua como fase móvil. El contenido de teobromina y cafeína disminuyó durante la fermentación para los dos tipos de cacao. El contenido de teobromina fue menor en el cacao criollo. Así mismo la relación teobromina: cafeína fue inferior para los cacaos tipos Criollo, indicando que estos son menos amargos que los híbridos

The space of signed points and the Self Dual Model

We study a generalization of the group of loops based on sets of signed points, instead of paths or loops. This geometrical setting incorporates the kinematical constraints of the Sigma Model, inasmuch as the the group of loops does with the Bianchi identities of Yang-Mills theories. We employ an Abelian version of this construction to quantize the Self-Dual Model, which allows us to relate this theory with that of a massless scalar field obeying non-trivial boundary conditions.Comment: (9 pages

Teratoma quístico mediastinal. Reporte de dos casos.

Los teratomas extragonadales son más frecuentes en la región sacro coccígea y en el mediastino. En el presente trabajo se reportan dos casos de teratomas mediastinales que simularon procesos infecciosos. Estos casos se presentaron en el primer semestre del año 2000 y representan la casuística del Instituto Autónomo Hospital Universitario de los Andes (IAHULA) en un periodo de diez años (1996-2005). Dos pacientes pediátricos de 10 años y 8 meses de edad respectivamente, ingresaron con los diagnósticos de absceso pulmonar y bronconeumonía con manifestaciones clínicas de tos, disnea, malestar general y fiebre. Se realizó toracotomia posterolateral con resección total de la neoplasia. En ambos casos la pieza quirúrgica correspondió a masa tumoral multiloculada, con espacios ocupados por material sebáceo, pelos y sangre. Histológicamente se demostró la presencia de células neoplásicas parenquimatosas derivadas de más de un estrato germinal. Los teratomas mediastinales son poco frecuente durante la infancia, pero el diagnóstico debe ser considerado en niños con sintomatología respiratoria. El diagnóstico definitivo se realizó después del examen morfológico de la pieza quirúrgica. El diagnóstico microscópico fue sencillo y no requirió de técnicas histológicas adicionales. El tratamiento de elección en estos casos es quirúrgico. La evolución de los pacientes cinco años después es satisfactoria

Structure and evolution of self-gravitating objects and the orthogonal splitting of the Riemann tensor

The full set of equations governing the structure and the evolution of self--gravitating spherically symmetric dissipative fluids with anisotropic stresses, is written down in terms of five scalar quantities obtained from the orthogonal splitting of the Riemann tensor, in the context of general relativity. It is shown that these scalars are directly related to fundamental properties of the fluid distribution, such as: energy density, energy density inhomogeneity, local anisotropy of pressure, dissipative flux and the active gravitational mass. It is also shown that in the static case, all possible solutions to Einstein equations may be expressed explicitly through these scalars. Some solutions are exhibited to illustrate this point.Comment: 32 pages, Late

Serological and molecular detection of dengue virus in animals: A systematic review and meta-analysis

Introduction: Dengue is a vector-borne disease, especially important in tropical and subtropical areas. The first presentation of many arboviral diseases occurred mainly in animals, including multiple Alphaviruses and Flaviviruses, such as dengue. Objective: To determine the serological and molecular frequency of the dengue virus in animals. Methods: A systematic literature review was carried out in five databases for the proportion of animals infected with dengue, defined by molecular and serological tests. A meta-analysis was performed using a randomeffects model to calculate the pooled prevalence and 95% confidence intervals (CI). Cochran?s Q test and the I2 statistic were used to assess the heterogeneity between the two studies. Results: The presence of dengue in bats, primates, birds, sheep, horses, cattle, pigs, rodents and buffaloes, according to serological methods, had a prevalence of 10%, 29%, 8%, 1%, 11%, 0%, 49%, 2%, 7%, respectively. According to molecular methods, the presence of dengue in bats had a seroprevalence of 6.0%. Conclusion: The present study confirms the presence of the Dengue virus in a large group of animal species, with potential implications as possible reservoirs of this virus, raising the possibility of zoonotic transmission.Revisión por pare