137 research outputs found
Elliptic curves of large rank and small conductor
For r=6,7,...,11 we find an elliptic curve E/Q of rank at least r and the
smallest conductor known, improving on the previous records by factors ranging
from 1.0136 (for r=6) to over 100 (for r=10 and r=11). We describe our search
methods, and tabulate, for each r=5,6,...,11, the five curves of lowest
conductor, and (except for r=11) also the five of lowest absolute discriminant,
that we found.Comment: 16 pages, including tables and one .eps figure; to appear in the
Proceedings of ANTS-6 (June 2004, Burlington, VT). Revised somewhat after
comments by J.Silverman on the previous draft, and again to get the correct
page break
Chromomagnetic Dipole Moment of the Top Quark Revisited
We study the complete one-loop contributions to the chromagnetic dipole
moment of the top quark in the Standard Model, two Higgs doublet
models, topcolor assited technicolor models (TC2), 331 models and extended
models with a single extra dimension. We find that the SM predicts
and that the predictions of the other models are also
consitent with the constraints imposed on by low-energy
precision measurements.Comment: 20 pages, 5 figures, Updat
Tune in to your emotions: a robust personalized affective music player
The emotional power of music is exploited in a personalized affective music player (AMP) that selects music for mood enhancement. A biosignal approach is used to measure listenersâ personal emotional reactions to their own music as input for affective user models. Regression and kernel density estimation are applied to model the physiological changes the music elicits. Using these models, personalized music selections based on an affective goal state can be made. The AMP was validated in real-world trials over the course of several weeks. Results show that our models can cope with noisy situations and handle large inter-individual differences in the music domain. The AMP augments music listening where its techniques enable automated affect guidance. Our approach provides valuable insights for affective computing and user modeling, for which the AMP is a suitable carrier application
BIOLEACHING OF COBALT AND ZINC FROM PYRITE ORE IN RELATION TO CALCITIC GANGUE CONTENT
Bioleaching of a pyrite ore containing high concentrations of cobalt (0.1%) and zinc (0.065%) was affected by small amounts of calcitic gangue (from 0.01 to 1.01%). Results from an air-lift percolator and from Erlenmeyer flask experiments show that a small percentage of calcite raises the pH and arrests the growth of the acidophilic bacterium Thiobacillus ferrooxidans. In percolator experiments, when calcite is completely removed by the continuous addition of small quantities of acid, and the pH of the liquor becomes acid, the micro-organism begins to grow and to bio-oxidize the pyrite ore. The growth of T. ferrooxidans shows different lag phase spans (from 13 to 190 days) depending on carbonate dissolution. The metals Fe, Zn and Co are released into the leaching solution together at different rates after a lag-time which depends on calcite concentrations in pyrite gangue. Metal ratios in the mineral bulk are different from those in the liquor, Zn dissolving 5 times more readily than Co. Bioleaching rates for metal removal from pyrite are higher in percolator (for Fe, from 5 to 15 mg/l/h) than in flask experiments (from 0.5 to 2 mg/l/h), but the lag phases are shorter (from 2 to 65 days). The differences between the two systems are related to calcite dissolution and gypsum precipitation
Avaliação das caracterĂsticas do lĂquido ruminal, hemogasometria, atividade pedomĂ©trica e diagnĂłstico de laminite subclĂnica em vacas leiteiras
Este estudo objetivou avaliar as caracterĂsticas do lĂquido ruminal, hemogasometria, atividade pedomĂ©trica e ocorrĂȘncia laminite subclĂnica, por meio da presença de enfermidades podais secundĂĄrias, em vacas leiteiras de alta produção, provenientes de um rebanho comercial. Foram avaliadas 200 vacas holandesas, oriundas da mesma propriedade, localizada na regiĂŁo de Araçatuba, SP, divididas em quatro grupos, sendo estes estabelecidos a partir da produtividade diĂĄria. Inicialmente procedeu-se o exame clĂnico dos animais, seguido da colheita de amostras do lĂquido ruminal, por meio de sondagem esofĂĄgica, sendo este avaliado quanto ao pH, cor, odor, consistĂȘncia, sedimentação, flutuação e prova de redução pelo azul de metileno. TambĂ©m foram colhidas amostras de sangue venoso para hemogasometria, alĂ©m da coleta dos dados da pedometria (nĂșmero de passos) e produção de leite diĂĄria das vacas. Os dados obtidos foram tabulados e submetidos Ă anĂĄlise de correlação. Nenhum animal avaliado apresentou alteraçÔes no pH ruminal, bem como nĂŁo foram encontrados distĂșrbios do desequilĂbrio ĂĄcido bĂĄsico, pois os valores de pH sanguĂneo, PCO2, TCO2, HCO3- e EB estavam dentro da normalidade, durante a anĂĄlise hemogasomĂ©trica. A pedometria foi efetiva como mĂ©todo de triagem para as vacas acometidas de afecçÔes podais, pois se observou a redução no nĂșmero de passos devido Ă dor, correlacionada a menor produção leiteira. Contudo, a identificação destas afecçÔes, somente foi possĂvel mediante exame clĂnico especĂfico dos dĂgitos. A ocorrĂȘncia das afecçÔes podais em 49,5% do rebanho deveu-se aos fatores de riscos presentes na propriedade, como o concreto abrasivo e instalaçÔes inadequadas, associados tambĂ©m a possĂvel ocorrĂȘncia de acidose ruminal subaguda, nĂŁo diagnosticada pela metodologia utilizada. A correlação entre os valores do pH ruminal, pedometria e hemogasometria se mostrou eficiente para o diagnĂłstico precoce das afecçÔes podais e tambĂ©m no estabelecimento da etiologia destas enfermidades. A laminite subclĂnica acometeu primariamente as vacas do rebanho, considerando a etiologia multifatorial desta afecção, ocorrĂȘncia e distribuição das enfermidades podais diagnosticadas
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