304 research outputs found

    Traditional systems of goat management. III. Reproductive performance of SRD (Non-descript) does and kid mortality.

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    Abstract: The reproductive performance of 50 adult SRD does maintained in native caatinga pasture at a stocking rate of 1 to 1.5 ha/head/year was evaluated. Two bucks were used in natural matings from September 1978 until December 1980. A total of 93 kiddings and 28 abortions occurred. Three pregnancies occurred before initiation of the experiment. From the 90 parturitions, 57.7%, 35.6%, 1.1 % and 5.6% bore singles, twins, triplets and undetermined, respectively. The flock showed an overall prolificacy of 1.38. From the initial fIock, 15(30%), 28(56%), 5(10%) and 2(4%) does presented one, two, three and zero kiddings, respectively during the period of study. Neither gestation length nor kidding interval were influenced by type of birth. Length of open period was influenced by season of the year when data were classified by season and kidding status at the open period. Combination of kidding type at previous and following kiddings showed a significant influence (P < 0.05) on the length of the open period. AnimaIs which kidded first singles and then singles or twins showed a shorter open period than animaIs which firstly kidded twins and then aborted at the following pregnant (109 Ys 188 days). The peak of kid mortality occurred between 7 and 112 days of age. Kid mortality appears not to be influenced by sex or type of birth. Overall kid mortality was 76%. The age at dead of kids was influenced by season and sex as weil as by their interaction. Males bom during the rainyseason survived longer than any other class studied. [Sistema tradicional de manejo de caprinos. III. Desempenho reprodutivo de caprinos SRD e mortalidade de cabritos]. Resumo: Avaliou-se o desempenho de 50 fêmeas de cabras SRD adultas mantidas em um piquete de pastagem nativa com uma lotação de 1 a 1,5 ha/cab/ano. Neste rebanho, dois reprodutores foram usados em monta natural de setembro de 1978 a dezembro de 1980. Foram observados 93 partos e 28 abortos. Ocorreram três prenhezes antes do início do experimento. Dos 90 partos restantes, 57,1%, 35,6%, 1,1% e 5,6% forem simples, duplos, triplos e não determinados, respectivamente. O rebanho mostrou uma prolificidade de 1,38. Para o rebanho inicial 15 (30%), 28 (56%), 5 (10%) e 2 (4%) das cabras pariram uma, duas, três e nenhuma vez, respectivamente, durante o período estudado. O período de gestação e o intervalo entre os partos não foram influenciados pelo tipo de nascimento. O período vazio foi influenciado pela estação do ano, quando os dados foram classificados por estação e tipo de parto. A combinação do tipo de parto, na parição inicial e na parição seguinte, teve influência significativa no período vazio. Os animais que pariram primeiramente simples e depois simples ou duplos apresentaram um período vazio menor (109 vs 188 dias) do que os animais que pariram primeiramente múltiplos e depois abortaram na prenhez seguinte. O pique de mortalidade (32%) ocorreu entre 7 e 112 dias de idade. A mortalidade de cabritos parece não ter sido influenciada pelo sexo e tipo de nascimento. A mortalidade total das crias foi de 76%. A idade à morte desses animais foi influencieda pela estação, sexo e interação de ambos. Os machos nascidos durante a estação chuvosa sobreviveram mais tempo do que os nascidos nas outras classes estudadas

    Cosmological Implications of a Non-Separable 5D Solution of the Vacuum Einstein Field Equations

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    An exact class of solutions of the 5D vacuum Einstein field equations (EFEs) is obtained. The metric coefficients are found to be non-separable functions of time and the extra coordinate ll and the induced metric on ll = constant hypersurfaces has the form of a Friedmann-Robertson-Walker cosmology. The 5D manifold and 3D and 4D submanifolds are in general curved, which distinguishes this solution from previous ones in the literature. The singularity structure of the manifold is explored: some models in the class do not exhibit a big bang, while other exhibit a big bang and a big crunch. For the models with an initial singularity, the equation of state of the induced matter evolves from radiation like at early epochs to Milne-like at late times and the big bang manifests itself as a singular hypersurface in 5D. The projection of comoving 5D null geodesics onto the 4D submanifold is shown to be compatible with standard 4D comoving trajectories, while the expansion of 5D null congruences is shown to be in line with conventional notions of the Hubble expansion.Comment: 8 pages, in press in J. Math. Phy

    Traditional system of goat management. II. Postweaning growth performance of the SRD (Nondescript) goats.

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    Abstract: The pattern of growth of SRD kids from an average of 153 days up to approximately 461 days of age was studied. Weights at the ages of 153 (W 5 ), 181 (W5), 209 (W7 ), 237 (W8 ), 265 (W9 ), 293 (W10 ), 321 (VI 1 ), 349 (W1 2), 461 (W15 ) days and calculated weight gains (G) between every weight interval G5 - (W5 - Weaning weight) through G12 - (W1 2 - W 1 ) were evaluated. Data were initially recorded on 54 kids and diminished thereafter at every interval due to kid mortaiity. The least squares analysis of vaiiance showed a significant season of birth effect (P 0.05) with the exception of type of birth for G 12 (P 0,05), com excecao do tipo de nascimento para G12 (P<0,025). As covariancias de peso da mae ao parto e idade do cabrito no momento da pesagem, foram significativas em algumas idades. Ja para o peso ao nascer, a covariavel foi significativa para P7, P8, P10 (P<0,005), P9 (P<0,001), P6, P11 e G12 (P<0,025)

    Effective spacetime from multi-dimensional gravity

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    We study the effective spacetimes in lower dimensions that can be extracted from a multidimensional generalization of the Schwarzschild-Tangherlini spacetimes derived by Fadeev, Ivashchuk and Melnikov ({\it Phys. Lett,} {\bf A 161} (1991) 98). The higher-dimensional spacetime has D=(4+n+m)D = (4 + n + m) dimensions, where nn and mm are the number of "internal" and "external" extra dimensions, respectively. We analyze the effective (4+n)(4 + n) spacetime obtained after dimensional reduction of the mm external dimensions. We find that when the mm extra dimensions are compact (i) the physics in lower dimensions is independent of mm and the character of the singularities in higher dimensions, and (ii) the total gravitational mass MM of the effective matter distribution is less than the Schwarzshild mass. In contrast, when the mm extra dimensions are large this is not so; the physics in (4+n)(4 + n) does explicitly depend on mm, as well as on the nature of the singularities in high dimensions, and the mass of the effective matter distribution (with the exception of wormhole-like distributions) is bigger than the Schwarzshild mass. These results may be relevant to observations for an experimental/observational test of the theory.Comment: A typo in Eq. (24) is fixe

    Características espermáticas de caprinos Moxotó de acordo com a morfologia escrotal.

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    bitstream/item/36457/1/CT-06.pd

    Reconstruction of Five-dimensional Bounce cosmological Models From Deceleration Factor

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    In this paper, we consider a class of five-dimensional Ricci-flat vacuum solutions, which contain two arbitrary functions μ(t)\mu(t) and ν(t)\nu(t). It is shown that μ(t)\mu(t) can be rewritten as a new arbitrary function f(z)f(z) in terms of redshift zz and the f(z)f(z) can be determined by choosing particular deceleration parameters q(z)q(z) which gives early deceleration and late time acceleration. In this way, the 5D5D cosmological model can be reconstructed and the evolution of the universe can be determined.Comment: 5 pages, 1 figure, to be published in IJT

    Self-similar cosmologies in 5D: Our universe as a topological separation from an empty 5D Minkowski space

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    In this paper we find the most general self-similar, homogeneous and isotropic, Ricci flat cosmologies in 5D. These cosmologies show a number of interesting features: (i) the field equations allow a complete integration in terms of one arbitrary function of the similarity variable, and a free parameter; (ii) the three-dimensional spatial surfaces are flat; (iii) the extra dimension is spacelike; (iv) the general solution is Riemann-flat in 5D but curved in 4D, which means that an observer confined to 4D spacetime can relate this curvature to the presence of matter, as determined by the Einstein equations in 4D. We show that these cosmologies can be interpreted, or used, as 5D Riemann-flat embeddings for spatially-flat FRW cosmologies in 4D. In this interpretation our universe arises as a topological separation from an empty 5D Minkowski space, as envisioned by Zeldovich

    Stabilization of test particles in Induced Matter Kaluza-Klein theory

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    The stability conditions for the motion of classical test particles in an n% n -dimensional Induced Matter Kaluza-Klein theory is studied. We show that stabilization requires a variance of the strong energy condition for the induced matter to hold and that it is related to the hierarchy problem. Stabilization of test particles in a FRW universe is also discussed.Comment: 15 pages, 1 figure, to appear in Class. Quantum Gra

    Active gravitational mass and the invariant characterization of Reissner-Nordstrom spacetime

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    We analyse the concept of active gravitational mass for Reissner-Nordstrom spacetime in terms of scalar polynomial invariants and the Karlhede classification. We show that while the Kretschmann scalar does not produce the expected expression for the active gravitational mass, both scalar polynomial invariants formed from the Weyl tensor, and the Cartan scalars, do.Comment: 6 pages Latex, to appear in General Relativity and Gravitatio

    Embeddings in Spacetimes Sourced by Scalar Fields

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    The extension of the Campbell-Magaard embedding theorem to general relativity with minimally-coupled scalar fields is formulated and proven. The result is applied to the case of a self-interacting scalar field for which new embeddings are found, and to Brans-Dicke theory. The relationship between Campbell-Magaard theorem and the general relativity, Cauchy and initial value problems is outlined.Comment: RevTEX (11 pages)/ To appear in the Journal of Mathematical Physic
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