Uso e cobertura das terras na área de entorno do reservatório da Usina Hidrelétrica de Tombos (MG).

O trabalho mapeia o uso e cobertura vegetal das terras na área de entorno do reservatório da UHE de Tombos. A metodologia utilizada combinou práticas de geoprocessamento, produtos de sensoriamento remoto, sistema de informação geográfica (SIG) e trabalhos de campo. Os resultados mostram que a maior parte da área encontra-se recoberta com pastagens, sendo 41,11% com pasto limpo e 15,10% com pasto sujo, seguidos de matas com 15,29% da área, os demais 28,4% corresponde às outras classes de uso

Increased levels of Stress-inducible phosphoprotein-1 accelerates amyloid-β deposition in a mouse model of Alzheimer’s disease

Molecular chaperones and co-chaperones, which are part of the protein quality control machinery, have been shown to regulate distinct aspects of Alzheimer’s Disease (AD) pathology in multiple ways. Notably, the co-chaperone STI1, which presents increased levels in AD, can protect mammalian neurons from amyloid-β toxicity in vitro and reduced STI1 levels worsen Aβ toxicity in C. elegans. However, whether increased STI1 levels can protect neurons in vivo remains unknown. We determined that overexpression of STI1 and/or Hsp90 protected C. elegans expressing Aβ(3–42) against Aβ-mediated paralysis. Mammalian neurons were also protected by elevated levels of endogenous STI1 in vitro, and this effect was mainly due to extracellular STI1. Surprisingly, in the 5xFAD mouse model of AD, by overexpressing STI1, we find increased amyloid burden, which amplifies neurotoxicity and worsens spatial memory deficits in these mutants. Increased levels of STI1 disturbed the expression of Aβ-regulating enzymes (BACE1 and MMP-2), suggesting potential mechanisms by which amyloid burden is increased in mice. Notably, we observed that STI1 accumulates in dense-core AD plaques in both 5xFAD mice and human brain tissue. Our findings suggest that elevated levels of STI1 contribute to Aβ accumulation, and that STI1 is deposited in AD plaques in mice and humans. We conclude that despite the protective effects of STI1 in C. elegans and in mammalian cultured neurons, in vivo, the predominant effect of elevated STI1 is deleterious in AD

Orbital Magnetism in Ensembles of Parabolic Potentials

We study the magnetic susceptibility of an ensemble of non-interacting electrons confined by parabolic potentials and subjected to a perpendicular magnetic field at finite temperatures. We show that the behavior of the average susceptibility is qualitatively different from that of billiards. When averaged over the Fermi energy the susceptibility exhibits a large paramagnetic response only at certain special field values, corresponding to comensurate classical frequencies, being negligible elsewhere. We derive approximate analytical formulae for the susceptibility and compare the results with numerical calculations.Comment: 4 pages, 4 figures, REVTE

Stochastic stabilization of cosmological photons

The stability of photon trajectories in models of the Universe that have constant spatial curvature is determined by the sign of the curvature: they are exponentially unstable if the curvature is negative and stable if it is positive or zero. We demonstrate that random fluctuations in the curvature provide an additional stabilizing mechanism. This mechanism is analogous to the one responsible for stabilizing the stochastic Kapitsa pendulum. When the mean curvature is negative it is capable of stabilizing the photon trajectories; when the mean curvature is zero or positive it determines the characteristic frequency with which neighbouring trajectories oscillate about each other. In constant negative curvature models of the Universe that have compact topology, exponential instability implies chaos (e.g. mixing) in the photon dynamics. We discuss some consequences of stochastic stabilization in this context.Comment: 4 pages, 3 postscript figures in color which are also appropriate for black and white printers; v2 emphasizes relevance to flat as well as negatively curved cosmologies; to appear in J. Phys.

Physiological changes in serum glucidic and nitrogenic analytes from captive Argentine authoctonous caimans

The purpose of this study was to establish reference intervals for serum glucidic and nitrogenic analytes from captive northeastern Argentinean caimans, as well as to detect physiological variations related to species, sex, age, feeding and season. Serum samples from 223 healthy sub–adults specimens of Caiman latirostris (n = 109) and Caiman yacare (n = 114), 50% each sex, were obtained. Values for glucose (4.18 ± 0.82 versus 4.01 ± 0.66 mmol/l), fructosamine (179 ± 33 versus 162 ± 29 umol/l), urea (1.11 ± 0.25 versus 1.06 ± 0.22 mmol/l), creatinine (56.1 ± 12.4 versus 52.5 ± 10.6 umol/l), and uric acid (127 ± 23 versus 156 ± 26 umol/l), were obtained by spectrophotometric methods for C. latirostris and C. yacare, respectively. Uric acid was significantly lower (p < 0.05) in C. latirostris. Glucose and urea were higher in females from both species. Progress of age (increment of liveweight and dimensions) correlated with increases of all biochemical parameters, significantly for glucose. Values were lower in winter, except for uric acid. The feeding system used in a hatchery resulted in glucose, urea and creatinine values higher than those registered in zoo specimens. Data obtained are applicable for caiman nutritional control, as well as for the diagnosis and prevention of diseases

Resultados das unidades de demonstração de cultivares de soja da Embrapa conduzidas nos Estados de Mato Grosso e Rondônia.

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Calorímetro de gelo: uma abordagem histórica e experimental para o ensino de química na graduação

In addition to the usual advantage of an ice calorimeter of being able to measure slow heat changes, the instrument described here is extremely simple to construct and operate. Specific heat of aluminum, copper, lead and tin metals were determined using the ice calorimeter made with easily accessible materials. The values obtained from specific heat are near to those found in the literature and were 0.204; 0.030; 0.086; 0.046 cal/g °C with an error of theoretical values of 6.84; 1,64; 5.49 and 8.00% for aluminum, copper, lead and tin, respectively

The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS2

A family of phases, CoxTiS2 (0 ≤ x ≤ 0.75) has been prepared and characterised by powder X-ray and neutron diffraction, electrical and thermal transport property measurements, thermal analysis and SQUID magnetometry. With increasing cobalt content, the structure evolves from a disordered arrangement of cobalt ions in octahedral sites located in the van der Waals’ gap (x ≤ 0.2), through three different ordered vacancy phases, to a second disordered phase at x ≥ 0.67. Powder neutron diffraction reveals that both octahedral and tetrahedral inter-layer sites are occupied in Co0.67TiS2. Charge transfer from the cobalt guest to the TiS2 host affords a systematic tuning of the electrical and thermal transport properties. At low levels of cobalt intercalation (x < 0.1), the charge transfer increases the electrical conductivity sufficiently to offset the concomitant reduction in |S|. This, together with a reduction in the overall thermal conductivity leads to thermoelectric figures of merit that are 25 % higher than that of TiS2, ZT reaching 0.30 at 573 K for CoxTiS2 with 0.04 ≤ x ≤ 0.08. Whilst the electrical conductivity is further increased at higher cobalt contents, the reduction in |S| is more marked due to the higher charge carrier concentration. Furthermore both the charge carrier and lattice contributions to the thermal conductivity are increased in the electrically conductive ordered-vacancy phases, with the result that the thermoelectric performance is significantly degraded. These results illustrate the competition between the effects of charge transfer from guest to host and the disorder generated when cobalt cations are incorporated in the inter-layer space