Generation of Closed Timelike Curves with Rotating Superconductors

The spacetime metric around a rotating SuperConductive Ring (SCR) is deduced from the gravitomagnetic London moment in rotating superconductors. It is shown that theoretically it is possible to generate Closed Timelike Curves (CTC) with rotating SCRs. The possibility to use these CTC's to travel in time as initially idealized by G\"{o}del is investigated. It is shown however, that from a technology and experimental point of view these ideas are impossible to implement in the present context.Comment: 9 pages. Submitted to Classical and Quantum Gravit

Interação genótipo-ambiente em bovinos: revisão de estudos no Brasil.

bitstream/item/31742/1/Doc-365.pdfVersão eletrônica disponível em papel

Single observable concurrence measurement without simultaneous copies

We present a protocol that allows us to obtain the concurrence of any two qubit pure state by performing a minimal and optimal tomography of one of the subsystems through measuring a single observable of an ancillary four dimensional qudit. An implementation for a system of trapped ions is also proposed, which can be achieved with present day experimental techniques.Comment: 4 pages, 1 figur

Quintessence and Scalar Dark Matter in the Universe

Continuing with previous works, we present a cosmological model in which dark matter and dark energy are modeled by scalar fields $\Phi$ and $\Psi$, respectively, endowed with the scalar potentials $V(\Phi)=V_{o}[ \cosh {(\lambda \sqrt{\kappa_{o}}\Phi)}-1]$ and $\tilde{V}(\Psi)=\tilde{V_{o}}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Psi)}] ^{\beta}$. This model contains 95% of scalar field. We obtain that the scalar dark matter mass is $m_{\Phi}\sim 10^{-26}eV.$ The solution obtained allows us to recover the success of the standard CDM. The implications on the formation of structure are reviewed. We obtain that the minimal cutoff radio for this model is $r_{c}\sim 1.2 kpc.$Comment: 4 pages REVTeX, 3 eps color figures. Minor changes and references updated. To appear in Classical and Quantum Gravity as a Letter to the Editor. More information at http://www.fis.cinvestav.mx/~siddh/PHI

Estudo da interação genótipo-ambiente em rebanhos da raça Nelore na Amazônia Legal.

Tese (Mestrado em Ciência Animal) - Universidade Federal Rural Amazônia, Belém. Sob orientação da Dra. Cintia Righetti Marcondes

Entropic Entanglement Criteria for Continuous Variables

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known variance product tests in the case of Gaussian states. Furthermore, they involve only a pair of quadrature measurements, and will thus should prove extremely useful the experimental identification of entanglement.Comment: 4 pages, 2 figure

Omissão individual de micronutrientes em mudas de mogno.

Foi instalado um experimento em casa de vegetação na Embrapa Amazônia Oriental, Belém, Pará, em solução nutritiva, com omissão individual de micronutrientes, com o intuito de avaliar os efeitos causados pela omissão sobre algumas características de desenvolvimento em mudas de mogno, como: altura de mudas, diâmetro de caule, número de folhas e foliolos e produção de matéria seca de folhas, caule e raízes. O delineamento experimental foi o de blocos casualizados. As medições foram feitas inicialmente a cada 15 dias e mensais, após o quinto mês. Aos 240 dias de idade, já com a maioria das plantas apresentando algum sinal de deficiência, foram cortadas, separadas por partes e secas. Verificou-se que os nutrientes cuja omissão mais limitaram a produção de matéria seca foram: de folhas, Fe > Zn, B e Mn; de caule, Fe > Cu, Mn e B; e de raízes, Fe > B e Mn. Os nutrientes cuja omissão mais limitaram a altura de mudas foram o B e o Cu, igualmente. Para o diâmetro não houve resposta significativa à omissão dos nutrientes. De maneira geral, o Fe foi o nutriente cuja omissão mais limitou o desenvolvimento das mudas de mogno

Edge phonons in black phosphorus

Exfoliated black phosphorus has recently emerged as a new two-dimensional crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have potentially important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and the behavior of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements.Comment: 15 pages, 4 figure