777 research outputs found
First Record Of Sylvilagus Brasiliensis (linnaeus, 1758) (lagomorpha: Leporidae) In Rio Grande Do Norte State, Northeast Brazil
We document the first record of Sylvilagus brasiliensis (Linnaeus, 1758) in Rio Grande do Norte state, Brazil. An adult individual was photographed in October 2015 in the municipality of João Câmara. This is the northernmost report of this species for the Caatinga biome. This article also represents important data for the Rio Grande do Norte, since the mammal diversity of this state is practically unknown. © 2016 Check List and Authors.12
A CFD based approach for determination of ammonia concentration profile and flux from poultry houses with natural ventilation
The understanding of concentration and emissions distribution of gases such as ammonia (NH3) in agricultural installations is of growing importance due to its effect on health and productivity of animals and workers. The objective of this study was to use validated Computational Fluid Dynamics (CFD) model as a tool to predict NH3 concentration distribution and mass fluxes in a non-insulated broiler chicken installation with natural ventilation, typically found in subtropical and tropical contries. Results from this study indicated that simulation with CFD can be used to predict NH3 concentration distribution and mass flux inside similar installations with incident winds from different directions of entrance at the lateral opening of the installation. The most direct application of the proposed mode would be to help improving the existing buildings and also to help in the conception of new ones, and may also apply the model to help in the development of NH3 emission inventories
Macromolecular theory of solvation and structure in mixtures of colloids and polymers
The structural and thermodynamic properties of mixtures of colloidal spheres
and non-adsorbing polymer chains are studied within a novel general
two-component macromolecular liquid state approach applicable for all size
asymmetry ratios. The dilute limits, when one of the components is at infinite
dilution but the other concentrated, are presented and compared to field theory
and models which replace polymer coils with spheres. Whereas the derived
analytical results compare well, qualitatively and quantitatively, with
mean-field scaling laws where available, important differences from ``effective
sphere'' approaches are found for large polymer sizes or semi-dilute
concentrations.Comment: 23 pages, 10 figure
Epidemiological situation of bovine brucellosis in the State of Rondônia, Brazil
Realizou-se um estudo para caracterizar a situação epidemiológica da doença no Estado de Rondônia. O Estado foi estratificado em três circuitos produtores. Em cada circuito produtor foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 9.717 animais, provenientes de 927 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo, se pelo menos um animal foi reagente às duas provas sorológicas. As prevalências de focos e de animais infectados do Estado foram de 35,2% [32,1-38,4%] e 6,2% [4,9-7,6%], respectivamente. Os resultados para os circuitos pecuários foram: circuito 1, 41,9% [36,3-47,6%] e 8,3% [5,9-10,8%]; circuito 2, 31,7% [26,5-37,2%] e 5,9% [4,3-7,6%]; circuito 3, 31,9% [26,7-37,4%] e 4,6% [2,5-6,6%]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: histórico de aborto (OR= 1,42 [1,04-1,95]) e exploração de corte (OR= 1,75 [1,30-2,38]). ______________________________________________________________________________________________________________ ABSTRACTA study to characterize the brucellosis epidemiological situation in the State of Rondônia was carried out. The State was divided into three regions. Three hundred herds were randomly sampled in each region. A pre-established number of animals were sampled in each of these herds. From 927 herds and 9,717 serum samples were collected. In each herd, it was applied an epidemiological questionnaire regarding herd features and also husbandry and sanitary practices that could be associated with risk of infection. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in Rondônia State were 35.2% [32.1-38.4%] and 6.2% [4.9-7.6%], respectively. In the regions, the prevalences of infected herds and animals were, respectively: region 1, 41.9% [36.3-47.6%] and 8.3% [5.9-10.8%]; region 2, 31.7% [26.5-37.2%] and 5.9% [4.3-7.6%]; and region 3, 31.9% [26.7-37.4%] and 4.6% [2.5-6.6%]. The risk factors (odds ratio, OR) associated with the presence of the infection were: recent history of abortion (OR= 1.42 [1.04-1.95]) and beef herd (OR=1.75 [1.30-2.38])
1+3 Covariant Cosmic Microwave Background anisotropies II: The almost - Friedmann Lemaitre model
This is the second of a series of papers extending the 1+3 covariant and
gauge invariant treatment of kinetic theory to an examination of Cosmic
Microwave Background temperature anisotropies arising from inhomogeneities in
the early universe. The first paper dealt with algebraic issues.
Here we derive the mode form of the integrated Boltzmann equations, first,
giving a covariant version of the standard derivation using the mode recursion
relations, second, demonstrating the link to the multipole divergence equations
and finally various analytic ways of solving the resulting equations are
discussed.
A general integral form of solution is obtained for the equations with
Thomson scattering. The covariant Friedmann-Lemaitre multipole form of the
transport equations are found using the covariant and gauge-invariant
generalization of the Peebles and Yu expansion in Thompson scattering time. The
dispersion relations and damping scale are then obtained from the covariant
approach. The equations are integrated to give the covariant and
gauge-invariant equivalent of the canonical scalar sourced anisotropies.
We carry out a simple treatment of the matter dominated free-streaming
projection, slow decoupling, and tight-coupling cases, with the aim both giving
a unified transparent derivation of this range of results and clarifying the
connection between the more usual approaches (for example that of Hu and
Sugiyama) and the treatment for scalar perturbations (for example the treatment
of Challinor and Lasenby).Comment: To appear in Annals of Physic
Faraday rotation in graphene
We study magneto--optical properties of monolayer graphene by means of
quantum field theory methods in the framework of the Dirac model. We reveal a
good agreement between the Dirac model and a recent experiment on giant Faraday
rotation in cyclotron resonance. We also predict other regimes when the effects
are well pronounced. The general dependence of the Faraday rotation and
absorption on various parameters of samples is revealed both for suspended and
epitaxial graphene.Comment: 10 pp; v2: typos corrected and references added, v3, v4: small
changes and more reference
Quintessence and Gravitational Waves
We investigate some aspects of quintessence models with a non-minimally
coupled scalar field and in particular we show that it can behave as a
component of matter with . We study the
properties of gravitational waves in this class of models and discuss their
energy spectrum and the cosmic microwave background anisotropies they induce.
We also show that gravitational waves are damped by the anisotropic stress of
the radiation and that their energy spectrum may help to distinguish between
inverse power law potential and supergravity motivated potential. We finish by
a discussion on the constraints arising from their density parameter
\Omega_\GW.Comment: 21 pages, 18 figures, fianl version, accepted for publication in PR
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