2,026 research outputs found
Circus Models for Safety-Critical Java Programs
Safety-critical Java (SCJ) is a restriction of the real-time specification for Java to support the development and certification of safety-critical applications. The SCJ technology specification is the result of an international effort from industry and academia. In this paper, we present a formalization of the SCJ Level 1 execution model, formalize a translation strategy from SCJ into a refinement notation and describe a tool that largely automates the generation of the formal models. Our modelling language is part of the Circus family; at the core, we have Z, communicating sequential processes and Morgan’s calculus, but we also use object-oriented and timed constructs from the OhCircus and Circus Time variants. Our work is an essential ingredient for the development of refinement-based reasoning techniques for SCJ
Quasi-one-dimensional system as a high-temperature superconductor
It is well-known that quasi-one-dimensional superconductors suffer from the
pairing fluctuations that significantly reduce the superconducting temperature
or even completely suppress any coherent behavior. Here we demonstrate that a
coupling to a robust pair condensate changes the situation dramatically. In
this case the quasi-one-dimensional system can be a high temperature
superconductor governed by the proximity to the Lifshitz transition at which
the Fermi level approaches the lower edge of the single-particle spectrum.Comment: 5 pages, 1 figur
COMPARATIVE ANALYSIS OF THE EFFICIENCY OF THERMAL SYSTEMS BUILT WITH REFLECTIVE INSULATORS WITH AND WITHOUT VACUUM
The use of reflective surfaces functioning as thermal insulators has grown significantly over the years. Reflective thermal insulators are materials that have several characteristics such as low emissivity, low absorptivity and high reflectivity in the infrared spectrum. The use of these materials has grown very much lately, since they contain several important radioactive properties that minimize the heat loss of thermal systems and cooling systems that are used to block the heat on the roof of buildings. A system made of three surfaces of 430 stainless steel mirror was built to analyze the influence of reflective surfaces as a way to reduce the heat loss and thereby conserve the energy of a thermal system. The system was analyzed both with and without the presence of vacuum, and then compared with a system that contained glass wool between the stainless steel mirror walls, since this insulator is considered resistive and also broadly used around the world in thermal systems. The reflectivity and emissivity of the surfaces used were also measured in this experiment. A type K thermocouple was fixed on the wall of the system to obtain the temperature of the stainless steel mirror surfaces and to analyze the thermal behavior of each configuration used. The results showed an efficiency of 13% when the reflective surfaces were used to minimize the heat loss of the thermal system. However, the system with vacuum had the best outcome, a 60% efficiency. Both of these were compared to the system made of glass wool as a thermal insulator
Are all maximally entangled states pure?
We study if all maximally entangled states are pure through several
entanglement monotones. In the bipartite case, we find that the same conditions
which lead to the uniqueness of the entropy of entanglement as a measure of
entanglement, exclude the existence of maximally mixed entangled states. In the
multipartite scenario, our conclusions allow us to generalize the idea of
monogamy of entanglement: we establish the \textit{polygamy of entanglement},
expressing that if a general state is maximally entangled with respect to some
kind of multipartite entanglement, then it is necessarily factorized of any
other system.Comment: 5 pages, 1 figure. Proof of theorem 3 corrected e new results
concerning the asymptotic regime include
Anomalous electron trapping by localized magnetic fields
We consider an electron with an anomalous magnetic moment g>2 confined to a
plane and interacting with a nonzero magnetic field B perpendicular to the
plane. We show that if B has compact support and the magnetic flux in the
natural units is F\ge 0, the corresponding Pauli Hamiltonian has at least 1+[F]
bound states, without making any assumptions about the field profile.
Furthermore, in the zero-flux case there is a pair of bound states with
opposite spin orientations. Using a Birman-Schwinger technique, we extend the
last claim to a weak rotationally symmetric field with B(r) = O(r^{-2-\delta})
correcting thus a recent result. Finally, we show that under mild regularity
assumptions the existence can be proved for non-symmetric fields with tails as
well.Comment: A LaTeX file, 12 pages; to appear in J. Phys. A: Math. Ge
Suppression of Anderson localization of light and Brewster anomalies in disordered superlattices containing a dispersive metamaterial
Light propagation through 1D disordered structures composed of alternating
layers, with random thicknesses, of air and a dispersive metamaterial is
theoretically investigated. Both normal and oblique incidences are considered.
By means of numerical simulations and an analytical theory, we have established
that Anderson localization of light may be suppressed: (i) in the long
wavelength limit, for a finite angle of incidence which depends on the
parameters of the dispersive metamaterial; (ii) for isolated frequencies and
for specific angles of incidence, corresponding to Brewster anomalies in both
positive- and negative-refraction regimes of the dispersive metamaterial. These
results suggest that Anderson localization of light could be explored to
control and tune light propagation in disordered metamaterials.Comment: 4 two-column pages, 3 figure
Custos de formação e manutenção de jardins clonais de cajueiro anão precoce.
bitstream/CNPAT-2010/6972/1/Ct-066.pd
Diferentes doses de dinoprost induzem estro eficientemente no início do ciclo estral em ovelhas.
O agronegócio de ovinos no Brasil cresceu nos últimos anos. Todavia, o rebanho nacional ainda é pequeno e não atende à demanda interna de produtos ovinos (i.e. carne e peles). A ovelha tem um período de gestação de 150 dias e sua produção é limitada pela estacionalidade reprodutiva. Em altas latitudes, isto se intensifica, tendo-se apenas um parto por ano. Considerando seu curto puerpério, estes animais podem ter seu estro induzido e o intervalo de partos alcançar oito meses. Há vários protocolos de sincronização/indução de estro eficientes. Atualmente, buscam-se protocolos de menor duração, que garantam alto percentual de animais em estro, sincronia e fertilidade. Protocolos com permanência de dispositivos intravaginais inferior a oito dias necessitam de administração de prostaglandina para assegurar a lise luteal e ocorrência de estro. Assim, torna-se necessário conhecer como corpos lúteos (CLs) em diferentes idades no início do ciclo estral respondem a diferentes doses de luteolíticos. O objetivo desde estudo foi verificar os efeitos de duas doses de dinoprost sobre a sincronização de estro em ovelhas entre o quarto e sexto dia do ciclo estral. [Different doses of dinoprost induce estrus efficiently early in the estrous cycle in ewes]
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