Perfect Quantum Privacy Implies Nonlocality

Private states are those quantum states from which a perfectly secure cryptographic key can be extracted. They represent the basic unit of quantum privacy. In this work we show that all states belonging to this class violate a Bell inequality. This result establishes a connection between perfect privacy and nonlocality in the quantum domain.Comment: 4 pages, published versio

Causarum Investigatio and the Two Bell's Theorems of John Bell

"Bell's theorem" can refer to two different theorems that John Bell proved, the first in 1964 and the second in 1976. His 1964 theorem is the incompatibility of quantum phenomena with the joint assumptions of Locality and Predetermination. His 1976 theorem is their incompatibility with the single property of Local Causality. This is contrary to Bell's own later assertions, that his 1964 theorem began with the assumption of Local Causality, even if not by that name. Although the two Bell's theorems are logically equivalent, their assumptions are not. Hence, the earlier and later theorems suggest quite different conclusions, embraced by operationalists and realists, respectively. The key issue is whether Locality or Local Causality is the appropriate notion emanating from Relativistic Causality, and this rests on one's basic notion of causation. For operationalists the appropriate notion is what is here called the Principle of Agent-Causation, while for realists it is Reichenbach's Principle of common cause. By breaking down the latter into even more basic Postulates, it is possible to obtain a version of Bell's theorem in which each camp could reject one assumption, happy that the remaining assumptions reflect its weltanschauung. Formulating Bell's theorem in terms of causation is fruitful not just for attempting to reconcile the two camps, but also for better describing the ontology of different quantum interpretations and for more deeply understanding the implications of Bell's marvellous work.Comment: 24 pages. Prepared for proceedings of the "Quantum [Un]speakables II" conference (Vienna, 2014), to be published by Springe

Monte-Carlo calculation of longitudinal and transverse resistivities in a model Type-II superconductor

We study the effect of a transport current on the vortex-line lattice in isotropic type-II superconductors in the presence of strong thermal fluctuations by means of 'driven-diffusion' Monte Carlo simulations of a discretized London theory with finite magnetic penetration depth. We calculate the current-voltage (I-V) characteristics for various temperatures, for transverse as well as longitudinal currents I. From these characteristics, we estimate the linear resistivities R_xx=R_yy and R_zz and compare these with equilibrium results for the vortex-lattice structure factor and the helicity moduli. From this comparison a consistent picture arises, in which the melting of the flux-line lattice occurs in two stages for the system size considered. In the first stage of the melting, at a temperature T_m, the structure factor drops to zero and R_xx becomes finite. For a higher temperature T_z, the second stage takes place, in which the longitudinal superconducting coherence is lost, and R_zz becomes finite as well. We compare our results with related recent numerical work and experiments on cuprate superconductors.Comment: 4 pages, with eps figure

Exact Solutions of the Klein-Gordon Equation in the Presence of a Dyon, Magnetic Flux and Scalar Potential in the Specetime of Gravitational Defects

In this paper we analyse the relativistic quantum motion of a charged spin-0 particle in the presence of a dyon, Aharonov-Bohm magnetic field and scalar potential, in the spacetimes produced by an idealized cosmic string and global monopole. In order to develop this analysis, we assume that the dyon and the Aharonov-Bohm magnetic field are superposed to both gravitational defects. Two distinct configurations for the scalar potential, $S(r)$, are considered: $i)$ the potential proportional to the inverse of the radial distance, i.e., $S\propto1/r$, and $ii)$ the potential proportional to this distance, i.e., $S\propto r$. For both cases the center of the potentials coincide with the dyon's position. In the case of the cosmic string the Aharonov-Bohm magnetic field is considered along the defect, and for the global monopole this magnetic field pierces the defect. The energy spectra are computed for both cases and explicitly shown their dependence on the electrostatic and scalar coupling constants. Also we analyse scattering states of the Klein-Gordon equations, and show how the phase shifts depend on the geometry of the spacetime and on the coupling constants parameter.Comment: To be published in CQG. Minor comments adde

Síntese de frutooligossacarídeos a partir da β-frutofuranosidase obtida de Penicillium citreonigrum URM 4459

O objetivo deste trabalho foi sintetizar frutooligossacarídeos (FOS) a partir da β-frutofuranosidase (FTase) produzida em biorreator utilizando células livres de Penicillium citreonigrum. Para isso, o fungo foi cultivado em meio rico em sacarose (20% p/v) a 150 rpm, pH 6,5, 28ºC durante 61 h. Ao fim da fermentação, o sobrenadante obtido por filtração foi utilizado para determinação da atividade extracelular e síntese enzimática de FOS utilizando sacarose a 60% (p/v). A máxima atividade da β- frutofuranosidase extracelular produzida em biorreator (232,16 U/mL) foi obtida após 38 h de fermentação (produtividade de 6,11 U/mL.h). A concentração máxima de FOS foi observada após 24h de reação, correspondendo a um consumo de 30% (m/m) da sacarose inicial. O rendimento máximo de FOS obtido foi de 20% (m/m) em relação à concentração inicial de sacarose, resultando em níveis elevados de GF2 (18%, m/m) e baixos rendimentos de GF3 (1,5%, m/m) e GF4 (0,6%, m/m). Os resultados aqui apresentados sugerem utilização do fungo P. citreonigrum em processos que visem à produção de kestose por via enzimática. No entanto, estudos mais aprofundados são necessários para otimizar os parâmetros reacionais, e assim aumentar o rendimento do FOS

Universal properties for linelike melting of the vortex lattice

Using numerical results obtained within two models describing vortex matter (interacting elastic lines (Bose model) and uniformly frustrated XY-model) we establish universal properties of the melting transition within the linelike regime. These properties, which are captured correctly by both models, include the scaling of the melting temperature with anisotropy and magnetic field, the effective line tension of vortices in the liquid regime, the latent heat, the entropy jump per entanglement length, and relative jump of Josephson energy at the transition as compared to the latent heat. The universal properties can serve as experimental fingerprints of the linelike regime of melting. Comparison of the models allows us to establish boundaries of the linelike regime in temperature and magnetic field.Comment: Revtex, 12 pages, 2 EPS figure

Exigências em energia e proteína líquida para ovelhas da raça Santa Inês em lactação.

Objetivou-se determinar as necessidades de proteína e energia líquida de ovelhas em lactação submetidas a dois manejos nutricionais na gestação e dois tipos de gestação. Os ensaios experimentais foram conduzidos nas instalações do Laboratório de Metabolismo e Calorimetria Animal do Departamento de Zootecnia da Escola de Veterinária da UFMG. Foram utilizadas 28 ovelhas da raça Santa Inês, em um delineamento experimental inteiramente casualizado em arranjo fatorial 2x2, e considerou-se dois tipos de gestação (simples e gemelar) e dois tipos de manejo nutricional (com e sem restrição). As ovelhas eram colocadas sobre plataforma e contidas para realização da ordenha. Para análise dos dados referentes às semanas em lactação utilizou-se o modelo de medidas repetidas no tempo. Os grupos experimentais foram avaliados mediante utilização do teste SNK a 5% de significância. A produção de leite não foi afetada pelo manejo nutricional, bem como a quantidade de gordura, proteína, energia e as necessidades em energia e proteína. Portanto, ficou evidenciado neste estudo que somente o manejo nutricional não foi capaz de alterar as variáveis estudadas. Ovelhas com gestação dupla apresentaram maior produção de leite, maiores teores de gordura e proteína no leite bem como maior valor energético do mesmo. As necessidades em energia e proteína foram maiores para ovelhas com gestação dupla. A produção de leite e as necessidades em energia e proteína foram maiores até a décima semana de lactação. A exigência nutricional em energia e proteína acompanhou a curva de produção de leite. [Net requirement of protein and energy of Santa Inês ewe in lactation]. Abstract: This study aimed to obtain the protein and liquid energy requirements from lactating ewes under two nutritional managements during pregnancy and under two types of pregnancy. Experimental tests were conducted at the Animal Metabolism and Calorimetry Laboratory on Department of Animal Science from Veterinary School of UFMG. For the experimental testing, were used 28 Santa Ines sheeps in a completely randomized design under 2 x 2 factorial arrangement, considering two pregnancy types (single and double) and two nutritional managements (with and without restriction). Sheeps were placed on the platform and contained for milking. To analyse data regarding milking weeks it was used the model of repeated measures in time. The experimental groups were evaluated using the SNK test at 5% significance level. (1) Diets were compound of corn meal (Zea mays), soybean meal (Glycine max), chopped Tifton grass hay (Cynodon spp.) and limestone. Sheep?s specific mineralsupplement was offered ad libitum to the animals Milk production was not affected by nutritional management, as the amount of fat, protein and, energy from milk. The same results were observed to energy and protein requirements. This fact shows that the nutritional management, per se, was not able to change the variables studied. The double pregnancy produced more milk, fat and protein in milk increasing its energy value. Energy and protein requirements were higher in ewes with double pregnancy. Milk production, energy and protein requirements were higher until the tenth week of lactation. Energy and protein nutritional requirement followed the milk production curve