Técnicas de manejo reprodutivo em bovinos de corte.

Na pecuária de corte, a exploração comercial do sistema de cria se constitui na fase do sistema produtivo, que envolve a criação e o manejo não só das matrizes bovinas e seus respectivos bezerros ate a desmama, mas também das novilhas de reposição e dos touros. Esse sistema tem por objetivo a produção de bezerros desmamados que representa a maior fonte de receita do criador. A venda de vacas descartadas e outros animais, apesar de contribuírem para a produção total, e uma fonte de receita marginal, mas também muito importante para o criador. Portanto, a viabilidade do sistema vai depender da eficácia e eficiência com que são utilizados os meios disponíveis para a otimização da produtividade. O escopo deste trabalho foi o de apresentar e discutir as principais praticas de manejo reprodutivo, que visam a otimização da produtividade, na forma de quilos de peso vivo de bezerro desmamado por hectare/ano. As discussões e conceitos aqui apresentados tem como premissa o fato de que o melhor conhecimento das diversas variáveis envolvidas no processo proporcionaria ao criador maior base para a tomada de decisões.bitstream/item/104762/1/Tecnicas-de-manejo-reprodutivo.pd

Estratégias para aumento da eficiência reprodutiva e produtiva em bovinos de corte.

Na pecuária de corte, a exploração comercial do sistema de cria se constitui na fase do sistema produtivo, que envolve a criação e o manejo não só das matrizes bovinas e seus respectivos bezerros ate a desmama, mas também das novilhas de reposição e dos touros. Esse sistema tem por objetivo a produção de bezerros desmamados que representa a maior fonte de receita do criador. A venda de vacas descartadas e outros animais, apesar de contribuírem para a produção total, e uma fonte de receita marginal. Portanto, a viabilidade do sistema vai depender da eficácia e eficiência com que são utilizados os meios disponíveis para a otimização da produtividade. O escopo deste trabalho foi o de apresentar e discutir as principais praticas de manejo reprodutivo, que visam a otimização da produtividade, na forma de quilos de peso vivo de bezerro desmamado por hectare/ano. As discussões e conceitos aqui apresentados tem como premissa o fato de que o melhor conhecimento das diversas variáveis envolvidas no processo proporcionara ao criador maior base para a tomada de decisões.bitstream/item/132210/1/DOC071.pd

Estresse a desmama em bovinos de corte.

Relação mãe-cria. Aspectos anatômicos e fisiológicos do aparelho digestivo do bezerro. Comportamento de manutenção em bezerros. Desmama e o estresse da separação. Práticas de alimentação e manejo visando reduzir o estresse à desmama.bitstream/item/135779/1/DOC-62.pd

Superconducting/magnetic three state nanodevice for memory and reading applications

We present a simple nanodevice that can operate in two modes: i) three-state memory and ii) reading device. The nanodevice is fabricated with an array of ordered triangular-shaped nanomagnets embedded in a superconducting thin film. The input signal is ac current and the output signal is dc voltage. Vortex ratchet effect in combination with out of plane magnetic anisotropy of the nanomagnets is the background physics which governs the nanodevice performance.Comment: 10 pages, 4 figure

Early optical spectra of nova V1369 Cen show presence of Lithium

We present early high resolution spectroscopic observations of the nova V1369 Cen. We have detected an absorption feature at 6695.6 \AA\, that we have identified as blue--shifted $^7$Li I $\lambda$6708 \AA. The absorption line, moving at -550 km/s, was observed in five high-resolution spectra of the nova obtained at different epochs. On the basis of the intensity of this absorption line we infer that a single nova outburst can inject in the Galaxy $M_{Li} =$ 0.3 - 4.8 $\times 10^{-10}$ M$_{\odot}$. Given the current estimates of Galactic nova rate, this amount is sufficient to explain the puzzling origin of the overabundance of Lithium observed in young star populations.Comment: 6 pages, 5 figures, accepted for publication in ApJLetter

Measurements of vacuum magnetic birefringence using permanent dipole magnets: the PVLAS experiment

The PVLAS collaboration is presently assembling a new apparatus (at the INFN section of Ferrara, Italy) to detect vacuum magnetic birefringence (VMB). VMB is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Using the very same optical technique it is also possible to search for hypothetical low-mass particles interacting with two photons, such as axion-like (ALP) or millicharged particles (MCP). Here we report results of a scaled-down test setup and describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity ($>4\times 10^5$) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter $A_e$, which determines the strength of the nonlinear terms in the QED Lagrangian: $A_e^{\rm (PVLAS)} < 3.3 \times 10^{-21}$ T$^{-2}$ 95% c.l. Furthermore, new laboratory limits have been put on the inverse coupling constant of ALPs to two photons and confirmation of previous limits on the fractional charge of millicharged particles is given

Dynamics of formation and decay of coherence in a polariton condensate

We study the dynamics of formation and decay of a condensate of microcavity polaritons. We investigate the relationship between the number of particles, the emission's linewidth and its degree of linear polarization which serves as the order parameter. Tracking the condensate's formation, we show that, even when interactions are negligible, coherence is not determined only by occupation of the ground state. As a result of the competition between the coherent and thermal fractions of the condensate, the highest coherence is obtained some time after the particle number has reached its maximum

First results from the new PVLAS apparatus: a new limit on vacuum magnetic birefringence

Several groups are carrying out experiments to observe and measure vacuum magnetic birefringence, predicted by Quantum Electrodynamics (QED). We have started running the new PVLAS apparatus installed in Ferrara, Italy, and have measured a noise floor value for the unitary field magnetic birefringence of vacuum $\Delta n_u^{\rm (vac)}= (4\pm 20) \times 10^{-23}$ T$^{-2}$ (the error represents a 1$\sigma$ deviation). This measurement is compatible with zero and hence represents a new limit on vacuum magnetic birefringence deriving from non linear electrodynamics. This result reduces to a factor 50 the gap to be overcome to measure for the first time the value of $\Delta n_u^{\rm (vac,QED)}$ predicted by QED: $\Delta n_u^{\rm (vac,QED)}= 4\times 10^{-24}$ ~T$^{-2}$. These birefringence measurements also yield improved model-independent bounds on the coupling constant of axion-like particles to two photons, for masses greater than 1 meV, along with a factor two improvement of the fractional charge limit on millicharged particles (fermions and scalars), including neutrinos

New PVLAS model independent limit for the axion coupling to γγ\gamma\gamma for axion masses above 1meV

During 2014 the PVLAS experiment has started data taking with a new apparatus installed at the INFN Section of Ferrara, Italy. The main target of the experiment is the observation of magnetic birefringence of vacuum. According to QED, the ellipticity generated by the magnetic birefringence of vacuum in the experimental apparatus is expected to be $\psi^{\rm(QED)} \approx 5\times10^{-11}$. No ellipticity signal is present so far with a noise floor $\psi^{\rm(noise)} \approx 2.5\times10^{-9}$ after 210 hours of data taking. The resulting ellipticity limit provides the best model independent upper limit on the coupling of axions to $\gamma\gamma$ for axion masses above $10^{-3}$eV