Password secured sites: stepping forward with keystroke dynamics

Computer Authentication is a critical component of most computer systems – especially those used in e- Commerce activities over the internet. Global access to information makes security, namely the authentication process, a critical design issue in these systems. In what concerns to authentication, what is required is a reliable, hardware independent and efficient security system. In this paper, we propose an extension to a keystroke dynamics based security system. We provide evidence that completely software based systems can be as effective as expensive and cumbersome hardware based systems. Our system is a behavioral based system that captures the normal typing patterns of a user and uses that information, in addition to standard login/password security to provide a system that is user-friendly and very effective at detecting imposters. The results provide a means of dealing with enhanced security that is growing in demand in web-based applications based on ECommerce

Emergence of turbulence in an oscillating Bose-Einstein condensate

We report on the experimental observation of vortices tangle in an atomic BEC of Rb-87 atoms when an external oscillatory perturbation is introduced in the trap. The vortices tangle configuration is a signature of the presence of a turbulent regime in the cloud. We also show that this turbulent cloud has suppression of the aspect ratio inversion typically observed in quantum degenerate bosonic gases during free expansion. Instead, the cloud expands keeping the ratio between their axis constant. Turbulence in atomic superfluids may constitute an alternative system to investigate decay mechanisms as well as to test fundamental theoretical aspects in this field.Comment: accepted for Phys. Rev. Let

Magnetic Field Tomography

Neutral atoms may be trapped via the interaction of their magnetic dipole moment with magnetic field gradients. One of the possible schemes is the cloverleaf trap. It is often desirable to have at hand a fast and precise technique for measuring the magnetic field distribution. We introduce a novel diagnostic tool for instantaneous imaging the equipotential lines of a magnetic field within a region of space (the vacuum recipient) that is not accessible to massive probes. Our technique is based on spatially resolved observation of the fluorescence emitted by a hot beam of sodium atoms crossing a thin slice of resonant laser light within the magnetic field region to be investigated. The inhomogeneous magnetic field spatially modulates the resonance condition between the Zeeman-shifted hyperfine sublevels and the laser light and therefore the amount of scattered photons. We demonstrate this technique by mapping the field of our cloverleaf trap in three dimensions under various conditions.Comment: 8 pages, 8 figure

Fundamentos para gestão da produção de caprinos e ovinos: transição para maior eficiência dos sistemas.

O objetivo desse documento é apresentar princípios conceituais e práticos para a aplicação efetiva de gestão na propriedade para a produção de caprinos e ovinos, tendo em vista as peculiaridades dessas atividades dentro da propriedade, ou mesmo o perfil dos produtores que as têm como principais atividades, na maioria das vezes com baixa adoção de tecnologias e de forma tradicional. Decerto, em linhas gerais, grande parte do conteúdo apresentado aqui pode ser aplicado a qualquer outra atividade em que se esteja procurando uma maior organização e eficiência

Microextração em fase sólida: métodos analíticos práticos para extração de compostos voláteis de frutas.

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