Anisotropic distribution functions for spherical galaxies

A method is presented for finding anisotropic distribution functions for stellar systems with known, spherically symmetric, densities, which depends only on the two classical integrals of the energy and the magnitude of the angular momentum. It requires the density to be expressed as a sum of products of functions of the potential and of the radial coordinate. The solution corresponding to this type of density is in turn a sum of products of functions of the energy and of the magnitude of the angular momentum. The products of the density and its radial and transverse velocity dispersions can be also expressed as a sum of products of functions of the potential and of the radial coordinate. Several examples are given, including some of new anisotropic distribution functions. This device can be extended further to the related problem of finding two-integral distribution functions for axisymmetric galaxies.Comment: 5 figure

Electrode Polarization Effects in Broadband Dielectric Spectroscopy

In the present work, we provide broadband dielectric spectra showing strong electrode polarization effects for various materials, belonging to very different material classes. This includes both ionic and electronic conductors as, e.g., salt solutions, ionic liquids, human blood, and colossal-dielectric-constant materials. These data are intended to provide a broad data base enabling a critical test of the validity of phenomenological and microscopic models for electrode polarization. In the present work, the results are analyzed using a simple phenomenological equivalent-circuit description, involving a distributed parallel RC circuit element for the modeling of the weakly conducting regions close to the electrodes. Excellent fits of the experimental data are achieved in this way, demonstrating the universal applicability of this approach. In the investigated ionically conducting materials, we find the universal appearance of a second dispersion region due to electrode polarization, which is only revealed if measuring down to sufficiently low frequencies. This indicates the presence of a second charge-transport process in ionic conductors with blocking electrodes.Comment: 9 pages, 6 figures, experimental data are provided in electronic form (see "Data Conservancy"

Unbound states in quantum heterostructures

We report in this review on the electronic continuum states of semiconductor Quantum Wells and Quantum Dots and highlight the decisive part played by the virtual bound states in the optical properties of these structures. The two particles continuum states of Quantum Dots control the decoherence of the excited electron – hole states. The part played by Auger scattering in Quantum Dots is also discussed

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Influência da administração de extratos de duas plantas calcinogênicas sobre a fertilidade de ratos Effect of calcinogenic plant extracts on rat fertility

Investigou-se o efeito de extratos aquosos de Solanum malacoxylon (Sendter) Solanaceae (SM) (sin.: S. glaucophyllum) e Nierembergia veitchii (Hook) Solanaceae (NV), plantas calcinogênicas encontradas no Brasil, sobre a reprodução de ratos e sobre suas progênies. No experimento 1, ratos e ratas Wistar, em número variável conforme o grupo, receberam por via oral, durante os 40 dias anteriores ao acasalamento, extrato aquoso de ambas as plantas em dosagem equivalente à administração diária de 10,9g×kg-1 de planta seca. Os resultados foram comparados com os de um grupo tratado diariamente com vitamina D3 (3,0mg×kg-1) e com os de um grupo-controle (salina). No experimento 2, ratas prenhes receberam, por via oral, três diferentes doses dos extratos de ambas as plantas (equivalente à administração diária de 5,4; 10,9 e 21,7g×kg-1 de planta seca), durante toda a gestação. Os resultados foram comparados com três grupos tratados com vitamina D3 (0,75; 2,25 e 3,75mg×kg-1) e um grupo-controle (salina). Quando administradas antes da gestação, o ganho de peso das fêmeas e a fertilidade foram reduzidos nos grupos tratados com SM (11%) e vitamina D3 (11%). No grupo tratado com NV, a fertilidade também foi reduzida (25%), mas o desenvolvimento ponderal durante o tratamento não foi afetado. Nos grupos tratados com SM e vitamina D3 anterior à gestação, o número de filhotes por ninhada foi reduzido, assim como o seu peso ao nascer. Características de desenvolvimento e desempenho físico dos filhotes não foram afetados em nenhum dos grupos. O tratamento das fêmeas com extrato aquoso de SM durante a gestação causou redução significativa e dose-dependente nas características reprodutivas estudadas. O mesmo foi observado com as fêmeas tratadas com vitamina D3. Com o extrato aquoso de NV não foram observadas reduções nas taxas reprodutivas, quando as fêmeas foram tratadas durante a gestação. Com as doses 10,9 e 21,7g×kg-1 de NV foram observadas anomalias morfológicas fetais (2,3 e 0,1%, respectivamente), também presentes nos filhotes de fêmeas tratadas com vitamina D3 (2,25mg×kg-1). A presença de vitamina D3 e seus metabólitos nas plantas calcinogênicas provavelmente é responsável pela infertilidade observada, não somente devido à toxicidade sistêmica, mas também devido aos seus efeitos específicos sobre o aparelho reprodutor.<br>The effect of aqueous extract of Solanum malacoxylon (Sendter) Solanaceae (SM) (sin.: S. glaucophyllum) and Nierembergia veitchii (Hook) Solanaceae (NV), common calcinogenic plants in Brazil, on the reproduction of rats and on their offsprings was investigated. In one set of experiments, male and female Wistar rats were treated per os with aqueous extract of each plant at a dose corresponding to the daily administration of 10g×kg-1 of dried plant for 40 days before mating. In another set of experiments, pregnant rats were daily treated with three different doses of aqueous extracts of both plants (5.4; 10.9 and 21.7g×kg-1, equivalent to the administration of dried plants) from the first until the last day of pregnancy. Saline and vitamin D3 treated male, female and pregnant rats were used as control in both experimental procedures. When administered before the pregnancy, the weight gain and the fertility were reduced in groups treated with SM (11%) and vitamin D3 (11%). In the NV group, fertility was reduced (25%) but the weight gain was not affected. The number of pups per litter and their weight were reduced in groups SM and vitamin D3, but in all groups the body development of the offsprings was not adversely affected. The treatment of the dams with SM during pregnancy causes significant and dose-related reduction of the fertility, as well as with vitamin D3. With an aqueous extract from NV it was not observed a significant reduction of the fertility, but the pups (2.3% in group treated with NV 10.9g×kg-1 and 0,1% in group treated with NV 21.7g×kg-1) presented morphological abnormalities, that were also observed with vitamin D3 (2.25mg×kg-1) treatment. The presence of vitamin D3 and metabolites in the calcinogenic plants is probably responsible for the infertility, not only because their systemic toxicity, but also because of the direct effects on the reproductive system