146 research outputs found
Why disease due to Mycobacterium tuberculosis is less common than expected in HIV-positive patients in Edinburgh
AbstractBy December 1993, only five cases of tuberculosis were observed in the 1030 HIV-positive patients in Edinburgh, U.K., although, on the basis of historical tuberculin skin test data, between four and eight new cases of tuberculosis were expected per year. Of 310 HIV-positive patients, none of the 19 (6·1%) who were tuberculin skin test positive had developed tuberculosis after 87 months (average) of follow-up. It is suggested that new or re-infection is a more common cause of tuberculosis in HIV-positive patients than reactivation. Restriction fragment length polymorphism typing of Mycobacterium tuberculosis strains could confirm this hypothesis and support currently suggested additional infection control procedures
Geographic Information Systems(GIS) and Virtual Reality Models (VRM) to Improve the Analysis of Genetic and Silvicultural Trials
GIS systems have become core tools for mapping needs in forestry. During the last decade software platforms have expanded the basic capabilities of data storage and retrieval in map formats. Complex overlay procedures, terrain analysis, 3D modeling, spatial and geostatistical tools, and remote sensing integration have increased the power of space related information. In addition, new VRM have emerged as improved tools for visualization, simulation and teaching. Research field trials in forestry are usually established to minimize spatial environmental variation, however exploring this assumption �ex ante� or �ex post� has been always tedious and uncertain and has lacked the power of visualization and analysis. Powerful spatial statistical analyses and interpolation analyses may be integrated to visualize site variability, remove environmental trends or integrate those to conventional statistical analyses. We investigated the �ex post� analysis of a research trial using ARCMAP/GIS and ARCScene VRM tools (ESRI, Inc) in order to explore their utility for trial analysis. Detailed sampling activities investigating specific physiological or ecological process may take full advantage of GIS and VRM tools capabilities to understand site variability and locate highly representative sampling points. That information may be used for modeling based on the same spatial information.Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003
Dominance and Stand Structure Analyses of a GXE Interaction Trial
Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003
Carbendazim dissipation in the biomixture of on-farm biopurification systems and its effect on microbial communities
The impact of repeated carbendazim (CARB) applications on the extent of \CARB\ dissipation, the microbial diversity, the community level physiological profile (CLPP), and the enzymatic activity within the biomixture of an on-farm biopurification system was evaluated. After three successive \CARB\ applications, the \CARB\ dissipation efficiency was high; the efficiency of dissipation was 87%, 94% and 96% after each application, respectively. Although microbial enzymatic activity was affected significantly by \CARB\ application, it could recover after each \CARB\ pulse. Likewise, the numbers of cultivable bacteria, fungi and actinomycetes (as measured in CFUs) were slightly affected by the addition of CARB, but the inhibitory effect of the pesticide application was temporary. Denaturing gradient gel electrophoresis (DGGE) and Biolog Ecoplate assays demonstrated that the microbial populations remained relatively stable over time when compared to the control. The results obtained herein therefore demonstrate the high dissipation capacity of this biomixture and highlight the microbiological robustness of this biological system.This work was supported by FONDECYT project No 11100236
Combined microbiological test to assess changes in an organic matrix used to avoid agricultural soil contamination, exposed to an insecticide
Combined microbiological test (Biolog Ecoplate, denaturing gradient gel electrophoresis (DGGE) and Real Time PCR (qPCR)) were developed to evaluate the impact of repeated diazinon (DZN) applications at high concentration (40 mg kg-1) on microbial communities in a microcosm simulating the organic matrix (straw (50%): peat (25%): soil (25%) vv-1) of an pesticide biopurification system (PBS). Moreover, pesticide dissipation was also evaluated. After three successive exposition of DZN, dissipation efficiency was high; achieved 87%, 93% and 96% after each application, respectively showing a clear accelerated dissipation of this pesticide in the organic matrix. The results obtained with Biolog Ecoplate showed that community level physiological profiles were no affected by the addition of DZN. On the other hand, molecular assays (DGGE and QPCR) demonstrated that the microbial structure (bacteria and fungi) remained relatively stable over time with high DZN doses compared to control. Therefore, the results of the present study, clearly, demonstrate the high dissipation capacity of this biomixture and highlight the microbiological robustness of this biological system.Fil: Tortella, G. R.. Universidad de la Frontera. Nucleo Cientifico y Tecnologico En Recursos Naturales (bioren-ufro). Departamento de Ciencias Quimicas y Recursos Naturales; ChileFil: Salgado, E.. Universidad de la Frontera. Nucleo Cientifico y Tecnológico En Recursos Naturales; ChileFil: Cuozzo, Sergio Antonio. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); ArgentinaFil: Mella Herrera, R. A.. Universidad de la Frontera. Nucleo Cientifico y Tecnológico En Recursos Naturales; ChileFil: Parra, L.. Universidad de la Frontera. Núcleo CientÃfico y Tecnológico en Recursos Naturales; ChileFil: Diez, M. C.. Universidad de la Frontera. Nucleo Cientifico y Tecnológico En Recursos Naturales; ChileFil: Rubilar, O.. Universidad de la Frontera. Nucleo Cientifico y Tecnológico En Recursos Naturales; Chil
Covariance properties and regularization of conserved currents in tetrad gravity
We discuss the properties of the gravitational energy-momentum 3-form within
the tetrad formulation of general relativity theory. We derive the covariance
properties of the quantities describing the energy-momentum content under
Lorentz transformations of the tetrad. As an application, we consider the
computation of the total energy (mass) of some exact solutions of Einstein's
general relativity theory which describe compact sources with asymptotically
flat spacetime geometry. As it is known, depending on the choice of tetrad
frame, the formal total integral for such configurations may diverge. We
propose a natural regularization method which yields finite values for the
total energy-momentum of the system and demonstrate how it works on a number of
explicit examples.Comment: 36 pages, Revtex, no figures; small changes, published versio
Responsiveness of Diverse Families of Loblolly Pine to Fertilization: Eight-Year Results from SETRES-2
Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003
Invariant conserved currents in gravity theories: diffeomorphisms and local gauge symmetries
Previously, we have developed a general method to construct invariant
conserved currents and charges in gravitational theories with Lagrangians that
are invariant under spacetime diffeomorphisms and local Lorentz
transformations. This approach is now generalized to the case when the local
Lorentz group is replaced by an arbitrary local gauge group. The particular
examples include the Maxwell and Yang-Mills fields coupled to gravity with
Abelian and non-Abelian local internal symmetries, and the metric-affine
gravity in which the local Lorentz spacetime group is extended to the local
general linear group.Comment: 28 pages, Revte
Wave propagation in linear electrodynamics
The Fresnel equation governing the propagation of electromagnetic waves for
the most general linear constitutive law is derived. The wave normals are found
to lie, in general, on a fourth order surface. When the constitutive
coefficients satisfy the so-called reciprocity or closure relation, one can
define a duality operator on the space of the two-forms. We prove that the
closure relation is a sufficient condition for the reduction of the fourth
order surface to the familiar second order light cone structure. We finally
study whether this condition is also necessary.Comment: 13 pages. Phys. Rev. D, to appea
Non-minimal coupling of photons and axions
We establish a new self-consistent system of equations accounting for a
non-minimal interaction of gravitational, electromagnetic and axion fields. The
procedure is based on a non-minimal extension of the standard
Einstein-Maxwell-axion action. The general properties of a ten-parameter family
of non-minimal linear models are discussed. We apply this theory to the models
with pp-wave symmetry and consider propagation of electromagnetic waves
non-minimally coupled to the gravitational and axion fields. We focus on exact
solutions of electrodynamic equations, which describe quasi-minimal and
non-minimal optical activity induced by the axion field. We also discuss
empirical constraints on coupling parameters from astrophysical birefringence
and polarization rotation observations.Comment: 31 pages, 2 Tables; replaced with the final version published in
Classical and Quantum Gravit
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