Quantum corrected geodesics

We compute the graviton-induced corrections to the trajectory of a classical test particle. We show that the motion of the test particle is governed by an effective action given by the expectation value (with respect to the graviton state) of the classical action. We analyze the quantum corrected equations of motion for the test particle in two particular backgrounds: a Robertson Walker spacetime and a 2+1 dimensional spacetime with rotational symmetry. In both cases we show that the quantum corrected trajectory is not a geodesic of the background metric.Comment: LaTeX file, 15 pages, no figure

Comparison between an integral and algebraic formulation for the eddy diffusivity using the Copenhagen experimental dataset

In this work an algebraic formulation to evaluate the eddy diffusivities in the Convective Boundary Layer (CBL) is derived. The expression depends on the turbulence properties (z height dependence) and the distance from the source. It is based on the turbulent kinetic energy spectra and Taylor’s statistical diffusion theory. It has been tested and compared through an experimental dataset, with another complex integral formulation taken from the literature. The Agreement between the complex integral formulation and simple algebraic expression points out that this new parameterization is valid and can be used as a surrogate for eddy diffusivities in the inhomogeneous convective turbulence present in the CBL. The validation shows that the proposed algebraic vertical eddy diffusivity is suitable for application in advanced air quality regulatory models

Isolation of Salmonella enterica in opossum (Didelphis aurita and Didelphis albiventris) of the São Paulo State, Brazil

No Brasil, não há relato de estudos de Salmonella em gambás, sendo assim, este trabalho tem por objetivo determinar a frequência de isolamento de Salmonella enterica em gambás (D. aurita e D. albiventris) no Estado de São Paulo. No período de janeiro de 2005 a dezembro de 2006, foram necropsiados 106 D. aurita e 40 D. albiventris e colhidos fragmentos de intestinos delgado, grosso e suabe da cloaca. As amostras foram plaqueadas diretamente em ágar Mac Conkey, paralelamente suspendidas nos caldos Rappaport-Vassiliadis e Tetrationato e posteriormente plaqueados em ágar XLT4. As colônias sugestivas de Salmonella foram confirmadas através de provas bioquímicas e sorotipagem. Encontrou-se Salmonella enterica em 17,0% (18/106) dos D. aurita. Destes, 50% apresentaram positividade no intestino delgado (ID), 88,9% no intestino grosso (IG) e 66,7% na cloaca. Da espécie S. enterica, as subespécies encontradas foram: diarizonae (11,1%) houtenae e enterica (5,5% cada um); enquanto da subespécie S. enterica enterica os sorotipos foram Newport (83,3%), Typhimurium e Cerro (5,5% cada um). Nos D. albiventris, 17,5% (7/40) eram positivos, sendo que se encontraram 42,8% no ID, 85,7% no IG e 71,4% na cloaca. O sorotipo mais prevalente também foi Newport (71,4%), seguido por Typhimurium, Bareilly e Thompson (14,3% cada um). Através dos resultados obtidos neste estudo pode-se comprovar a presença de Salmonella enterica no trato intestinal de gambás no Brasil.In Brazil there is not report of Salmonella in opossum, so then, the objective of this study is to determine the isolation frequency of Salmonella enterica in opossum in São Paulo State, Brazil. From January 2005 to December 2006, 106 D. aurita and 40 D. albiventris were necropsied and samples from small and large intestine and cloacal swab were collected. These samples were submitted to direct plating in Mac Conkey agar and parallel suspension in Rappaport-Vassiliadis and Tetrationate broths with posterior streaking in XLT4 agar. The characterization of the isolates was done through biochemical tests and serotyping. Salmonella enterica was found in 17.0% (18/106) of the D. aurita; 50% presented the bacteria in the small intestine (SI), 88.9% in the large intestine (LI) and 66.7% in the cloaca. Of the S. enterica were found the subspecies: diarizonae (11.1%), enterica and houtenae (5.5% each); and the serotypes of the S. enterica enterica were Newport (83.3%), Typhimurium and Cerro (5.5% each). In the D. albiventris 17.5% (7/40) were positive; 42.8% in the SI, 85.7% in the LI and 71.4% in the cloaca. Newport (71.4%) was also the most frequent serotype and the second were Typhimurium, Bareilly and Thompson (14.3% each). The presence of Salmonella enterica in the intestines of opossums in Brazil was proved

An automatic methodology for estimating eddy diffusivities from experimental data

A technique for estimating eddy diffusivities in a turbulent atmospheric layer is presented; the scheme adopted is based on an inverse-problem methodology. The inverse problem is formulated as a nonlinear constrained optimization problem, where the objective function is defined through the square differences between experimental and model data. The direct mathematical model is given by the advection-diffusion equation, which is solved by second-order finite-difference method. In the presence of noise it is necessary to use some regularization term; the Tikhonov function and an entropic regularization of zeroth, first and second orders are used in this paper. In addition, two inversion strategies are used: alternate and simultaneous eddy diffusivities estimation. Numerical experiments show a good performance of the proposed methodology

Turbulent dispersion from tall stack in the unstable boundary layer: a comparison between Gaussian and K-diffusion modelling for non buoyant emissions

Most air quality dispersionmo dels used for regulatory applications are based onGaussianan d K-diffusionform ulations. The reliability of such models strongly depends on how dispersion parameters and eddy diffusivities are computed on the basis of the update understanding of the Planetary Boundary Layer (PBL) meteorology. In this paper, we compare the performances in simulating pollutants released from continuous point source, by using some Gaussian and K-diffusion models with different assumptions concerning the parameterisation of the dispersionpro cesses. Results show that the Gaussianmo del, inwhic h the dispersion parameters are directly related to spectral peak of turbulence energy, gives the best overall performances. This could be due to a more realistic description of spreading processes occurring into the PBL. This suggests that, in the context of the regulatory applications, this model cangiv e the best combinationb etweengroun d level concentration estimates and computer requirements

In situ estimation of indigestible compounds contents in cattle feed and feces using bags made from different textiles

The objective of this experiment was to evaluate estimates of concentration of indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) in samples of cattle feed and feces processed at different particle sizes (1-, 2-, and 3-mm) using bags made from nylon (50 μm), F57 (Ankom®), and non-woven textile (NWT - 100 g/m²) in a in situ evaluation procedure. Eight samples of concentrates, seven samples of forages and two samples of cattle feces were used. The samples were put in the bags according to a ratio of 20 mg of dry matter/cm² of surface by using three bags of each textile for each size of particle, totaling 405 bags, which were submitted to ruminal incubation for 264 hours. The contents of indigestible compounds in the samples were evaluated sequentially. Blank bags were used for microscopic evaluation of textile physical integrity and for evaluation of the physical resistance. The presence of contaminants caused high variability of results of iDM, indicating that its using as internal marker should not be recommended. By using the textiles F57 and NWT, similar estimates for contents of iNDF and iADF were obtained whereas by using nylon (50 μm), the concentration of iNDF was underestimated, possibly because of loss of particles due to its porosity. Nylon presented loss of resistance in all analytical stages, expanding its probality of rupture, especially after extraction with acid detergent. For in situ evaluation of indigestible compounds, it is suggested grinding samples in 2-mm screen sieves.Objetivou-se avaliar as estimativas de concentração de matéria seca (MSi), fibra em detergente neutro (FDNi) e fibra em detergente ácido (FDAi) indigestíveis em amostras de alimentos e fezes bovinas processadas em diferentes tamanhos de partículas (1, 2 e 3 mm) utilizando-se sacos confeccionados com os tecidos nylon (50 μm), F57 (Ankom®) e tecido não-tecido (TNT - 100 g/m²) em procedimento de avaliação in situ. Foram utilizadas oito amostras de alimentos concentrados, sete de alimentos volumosos e duas de fezes bovinas. O material foi acondicionado nos sacos numa relação de 20 mg de matéria seca/cm² de superfície utilizando-se três sacos de cada tecido para cada tamanho de partícula, totalizando 405 sacos, que foram submetidos a incubação ruminal durante 264 horas. Os teores dos compostos indigestíveis nas amostras foram avaliados sequencialmente. Sacos em branco foram utilizados para avaliação microscópica da integridade física dos tecidos e para avaliação da resistência à tração. A presença de contaminantes causou alta variabilidade dos resultados de MSi, o que indica comprometimento de sua aplicação como indicador interno. Utilizando os tecidos F57 e TNT obtiveram-se estimativas similares para os teores de FDNi e FDAi, enquanto com o tecido nylon (50 μm) a concentração de FDNi foi subestimada, possivelmente em decorrência da perda de partículas devido à sua porosidade. O nylon apresentou perda de resistência em todas as etapas analíticas, o que amplia sua probabilidade de ruptura, principalmente após extração com detergente ácido. Para procedimentos in situ de avaliação de compostos indigestíveis, sugere-se a moagem de amostras em peneiras com porosidade de 2 mm