Adolescent alcohol exposure alters threat avoidance in adulthood

Adolescent binge-like alcohol exposure impairs cognitive function and decision making in adulthood and may be associated with dysfunction of threat avoidance, a critical mechanism of survival which relies upon executive function. The present study investigated the impact of binge-like alcohol exposure during adolescence on active avoidance in adulthood. Male and female rats were subjected to adolescent intermittent ethanol (AIE) exposure by vapor inhalation and then tested in adulthood using a platform-mediated avoidance task. After training to press a lever to receive a sucrose reward, the rats were conditioned to a tone that co-terminated with a foot-shock. A motivational conflict was introduced by the presence of an escape platform that isolated the rat from the shock, but also prevented access to the sucrose reward while the rat was on the platform. During the task training phase, both male and female rats exhibited progressive increases in active avoidance (platform escape) in response to the conditioned tone, whereas innate fear behavior (freezing) remained relatively constant over training days. A history of AIE exposure did not impact either active avoidance or freezing behavior during task acquisition. On the test day following platform acquisition training, female rats exhibited higher levels of both active avoidance and freezing compared to male rats, while AIE-exposed male but not female rats exhibited significantly greater levels of active avoidance compared to controls. In contrast, neither male nor female AIE-exposed rats exhibited alterations in freezing compared to controls. Following 5 days of extinction training, female rats continued to display higher levels of active avoidance and freezing during tone presentation compared to males. Male AIE-exposed rats also had higher levels of both active avoidance and freezing compared to the male control rats. Together, the results demonstrate that female rats exhibit elevated levels of active avoidance and freezing compared to males and further reveal a sex-specific impact of AIE on threat responding in adulthood

Identification of a possible superconducting transition above room temperature in natural graphite crystals

Measuring with high precision the electrical resistance of highly ordered natural graphite samples from a Brazil mine, we have identified a transition at $\sim$350~K with $\sim$40~K transition width. The step-like change in temperature of the resistance, its magnetic irreversibility and time dependence after a field change, consistent with trapped flux and flux creep, and the partial magnetic flux expulsion obtained by magnetization measurements, suggest the existence of granular superconductivity below 350~K. The zero-field virgin state can only be reached again after zero field cooling the sample from above the transition. Paradoxically, the extraordinarily high transition temperature we found for this and several other graphite samples is the reason why this transition remained undetected so far. The existence of well ordered rhombohedral graphite phase in all measured samples has been proved by x-rays diffraction measurements, suggesting its interfaces with the Bernal phase as a possible origin for the high-temperature superconductivity, as theoretical studies predicted. The localization of granular superconductivity at these two dimensional interfaces prevents the observation of a zero resistance state or of a full Meissner state.Comment: 14 pages with 21 figure

Absence of correlation between built-in electric dipole moment and quantum Stark effect in InAs/GaAs self-assembled quantum dots

We report significant deviations from the usual quadratic dependence of the ground state interband transition energy on applied electric fields in InAs/GaAs self-assembled quantum dots. In particular, we show that conventional second-order perturbation theory fails to correctly describe the Stark shift for electric field below $F = 10$ kV/cm in high dots. Eight-band ${\bf k}\cdot{\bf p}$ calculations demonstrate this effect is predominantly due to the three-dimensional strain field distribution which for various dot shapes and stoichiometric compositions drastically affects the hole ground state. Our conclusions are supported by two independent experiments.Comment: 4 pages, 4 figure

Exploiting exciton-exciton interactions in semiconductor quantum dots for quantum-information processing

We propose an all-optical implementation of quantum-information processing in semiconductor quantum dots, where electron-hole excitations (excitons) serve as the computational degrees of freedom (qubits). We show that the strong dot confinement leads to an overall enhancement of Coulomb correlations and to a strong renormalization of the excitonic states, which can be exploited for performing conditional and unconditional qubit operations.Comment: 5 pages revtex, 2 encapsulated postscript figures. Accepted for publication in Phys. Rev. B (Rapid Communication

Características sensoriais da carne de cordeiros Morada Nova submetidos a dietas com diferentes níveis de farelo de castanha de caju.

Utilizou-se dezenove cordeiras Morada Nova, alimentadas com níveis crescentes de inclusão de farelo de castanha de caju (0, 3, 6 e 9%), abatidas ao atingirem peso médio de 20 kg e avaliadas suas características sensoriais de dureza, suculência, aroma, sabor e aceitação global, através de um painel com 10 julgadores treinados. Sendo observada diferença somente para os atributos cor e sabor, com a dieta com 6% de farelo de castanha de caju apresentado as maiores médias. Assim, a adição de farelo de castanha de caju na dieta de cordeiros Morada Nova influencia as características sensoriais de cor e sabor da carne, à medida que o nível de inclusão é elevado. Sensorial characteristics of the Morada Nova lambs meat submitted to diets with different levels of inclusion of cashew nut meal. Abstract: Nineteen lambs Morada Nova, fed with increasing levels of inclusion of cashew nut meal (0, 3, 6 and 9%) to reach slaughter body weight of 20 kg and to evaluate for their sensorial characteristic of tenderness, succulence, odour, flavor and global acceptance by a panel of 10 trained judges. Difference was observed only for color and flavor, in the diet with 6% of cashew nut meal presented the highest averages. Thus, the addition of cashew nut meal in the diet of Morada Nova lambs influence the sensorial characteristics of color and flavor of meat, as that the level inclusion is high

Características qualitativas da carcaça de cordeiros terminados em pastagem nativa da Caatinga, submetidos a diferentes suplementações de sal mineral.

Resumo: Objetivou-se determinar as características qualitativas da carcaça de cordeiros terminados em pastagem nativa da caatinga submetidos a diferentes suplementações de sal mineral. Foram utilizados 24 ovinos em terminação mestiços Santa Inês, distribuídos em um delineamento inteiramente casualizado, em três tratamentos, conforme as seguintes suplementações de sal mineral: sal mineral comercial (SALMINC), sal mineral comercial acrescido de 750 ppm de zinco animal-1 (SALMINCZn) e sal comercial com fornecimento de 2,5 ml por peso vivo metabólico (PV)0,75 animal-1 de propilenoglicol (SALMINCPeg), com oito repetições cada. Foram avaliadas as caracteristicas cor, área de olho de lombo/gabarito (cm2), área de olho de lombo/fórmula (cm2), espessura de gordura (mm), marmoreio da gordura (1-5), distribuição do marmoreio da gordura (1-3), textura da carne (1-5), textura da gordura (1-5). A única variável que diferiu entre os tratamentos avaliados foi a espessura de gordura (P<0,05). Os cordeiros que foram suplementados com sal mineral acrescido de 750 ppm de zinco apresentaram maior espessura de gordura. O uso de sal mineral com adição de Zinco influenciou na obtenção de uma maior espessura de gordura na carcaça de ovinos. [Qualitative carcass characteristics of lambs finished in native pasture of the Caatinga submitted to differents supplementations of mineral salt]. Abstract: The aim was to determine the qualitative characteristics of the carcass of lambs finished on native pasture of the Caatinga submitted to differents mineral salt supplementations. Were used 24 crossbred sheep Santa Ines in termination, distributed in a completely randomized design, with three treatments, according to the following supplements of mineral salt: commercial mineral salt (SALMINC), commercial mineral salt plus 750 ppm of zinc per animal-1 (SALMINCZn) and commercial mineral salt supply with 2.5 ml of propylene glycol per metabolic body weight (BW)0.75 animal-1 (SALMINCPeg), with eight replicates each. Were evaluated the characteristics of color, rib eye area/feedblack (cm2), rib eye area /formula (cm2), fat thickness (mm), marbling fat (1-5), distribution of marbling fat were evaluated (1-3), texture of meat (1-5), texture of fat (1-5). The only variable that differed among the treatments was the fat thickness (P <0.05). The lambs were supplemented with mineral salt plus zinc had greater fat thickness. The use of mineral salt added with zinc had influenced in getting of higher thickness carcass fat of sheep

Optical excitations of a self assembled artificial ion

By use of magneto-photoluminescence spectroscopy we demonstrate bias controlled single-electron charging of a single quantum dot. Neutral, single, and double charged excitons are identified in the optical spectra. At high magnetic fields one Zeeman component of the single charged exciton is found to be quenched, which is attributed to the competing effects of tunneling and spin-flip processes. Our experimental data are in good agreement with theoretical model calculations for situations where the spatial extent of the hole wave functions is smaller as compared to the electron wave functions.Comment: to be published in Physical Review B (rapid communication

Theoretical interpretation of the experimental electronic structure of lens shaped, self-assembled InAs/GaAs quantum dots

We adopt an atomistic pseudopotential description of the electronic structure of self-assembled, lens shaped InAs quantum dots within the ``linear combination of bulk bands'' method. We present a detailed comparison with experiment, including quantites such as the single particle electron and hole energy level spacings, the excitonic band gap, the electron-electron, hole-hole and electron hole Coulomb energies and the optical polarization anisotropy. We find a generally good agreement, which is improved even further for a dot composition where some Ga has diffused into the dots.Comment: 16 pages, 5 figures. Submitted to Physical Review

Effects of Metallicity on the Instability Mass Ratio of Low Mass Contact Binary Systems

The orbital stability of contact binary systems has been receiving considerable attention recently. Theoretical studies indicate that merger is likely to occur at very low mass ratios, but the actual mass ratio at which merger may take place is likely to be variable and dependent on the mass of the primary. We consider the effects of metal content on the orbital stability of contact binary systems by modelling the gyration radius of a rotating and tidally distorted primary component at various values of metallicity in the range -1.25 to +0.5. We determine the instability mass ratio range for contact binary systems with a low mass primary in the range 0.6M(sun) to 1.4M(sun) at various metallicity levels and show that systems with low metallicity have an instability mass ratio lower than those with higher metal content and therefore are likely to be more stable. We illustrate the effect through light curve analysis of two otherwise very similar contact binary systems, except for different metallicity. While both would be considered unstable if metallicity was not taken into consideration, only one remains in that category after appropriate adjustments based on metallicity have been made.Comment: 9 pages, 7 Figures and 5 Tables Accepted Monthly Notices of Royal Astronomical Society (MNRAS