Conformal gravity: light deflection revisited and the galactic rotation curve failure

We show how Conformal Gravity (CG) has to satisfy a fine-tuning condition to describe the rotation curves of disk galaxies without the aid of dark matter. Interpreting CG as a gauge natural theory yields conservation laws and their associated superpotentials without ambiguities. We consider the light deflection of a point-like lens and impose that the two Schwarzschild-like metrics with and without the lens are identical at infinite distances from the lens. The energy conservation law implies that the parameter $\gamma$ in the linear term of the metric has to vanish, otherwise the two metrics are physically inaccessible from each other. This linear term is responsible to mimic the role of dark matter in disk galaxies and gravitational lensing systems. Our analysis shows that removing the need of dark matter with CG thus relies on a fine-tuning condition on $\gamma$. We also illustrate why the results of previous investigations of gravitational lensing in CG largely disagree. These discrepancies derive from the erroneous use of the deflection angle definition adopted in General Relativity, where the vacuum solution is asymptotically flat, unlike CG. In addition, the lens mass is identified with various combinations of the metric parameters. However, these identifications are arbitrary, because the mass is not a conformally invariant quantity, unlike the conserved charge associated to the energy conservation law. Based on this conservation law and by removing the fine-tuning condition on $\gamma$, i.e. by setting $\gamma=0$, the energy difference between the metric with the point-like lens and the metric without it defines a conformally invariant quantity that can in principle be used for (1) a proper derivation of light deflection in CG, and (2) the identification of the lens mass with a function of the parameters $\beta$ and $k$ of the Schwarzschild-like metric.Comment: 16 pages, 1 figure. Revised version according to the referees comments. The results reported in the original version remain unchange

In memoriam two distinguished participants of the Bregenz Symmetries in Science Symposia: Marcos Moshinsky and Yurii Fedorovich Smirnov

Some particular facets of the numerous works by Marcos Moshinsky and Yurii Fedorovich Smirnov are presented in these notes. The accent is put on some of the common interests of Yurii and Marcos in physics, theoretical chemistry, and mathematical physics. These notes also contain some more personal memories of Yurii Smirnov.Comment: Submitted for publication in Journal of Physics: Conference Serie

Supplementation with spray-dried porcine plasma in piglets at birth: effects on protein metabolism and performance.

Resumo: Este estudo foi planejado para avaliar se a suplementação de leitões com plasma sanguíneo suíno desidratado (PSSP) no dia do nascimento tem efeito positivo sobre o metabolismo proteico e ganho de peso (GP) em leitões, bem como no desempenho na fase de creche. Selecionamos 30 leitegadas de marrãs, das quais, no mínimo um casal de leitões para cada tratamento/leitegada foi selecionado. Os tratamentos foram: TA = controle sem PSSP, TB = administração oral de 10 g de PSSP e TC = 20 g de PSSP. No nascimento, os leitões foram pesados, identificados e distribuídos aleatoriamente. Os pesos corporais também foram avaliados nos dias 7, 14 e 19. Foram coletadas amostras de sangue para medir o nível de uréia, proteína total (PT), albumina (AB) e globulina (GB). No desmame, 70 leitões de cada tratamento foram distribuídos em cinco grupos (réplicas) de 14 leitões (sete machos e sete fêmeas). Os dados de pesos (animais e consumo de ração) foram coletados no pós-desmame e também a cada troca de dieta (dias 14, 28 e 42 da fase de creche). Durante as duas primeiras semanas na maternidade, não houve efeitos dos tratamentos para todas as variáveis avaliadas. Na terceira semana, os leitões de TC apresentaram níveis séricos mais altos para as variáveis PT e GB, mas o GT foi menor nos leitões comparado ao controle. Não houve efeito dos tratamentos no GT durante todo o período lactente. Não houve efeitos residuais no desempenho da fase de creche; no entanto, os leitões tratados tiveram menos necessidade de medicamentos. A suplementação com PSSP não influenciou o desempenho zootécnico nas duas primeiras semanas ou durante todo o período lactente. O grupo TC apresentou níveis mais altos de globulina do que o grupo TA. Na fase de creche, não houve efeitos no desempenho; no entanto, houve uma maior incidência de animais doentes do grupo TA. Abstract: This research was designed to evaluate whether supplementation of piglets with spray dried porcine plasma (SDPP) on the day of birth, have positive effect on protein metabolism and weight gain (WG) in suckling piglets, as well as on performance at the nursery phase. We selected 30 litters from gilts of at least one pair of piglets for each treatment, TA= control without SDPP, TB= oral administration of 10 g of SDPP, and TC= 20 g of SDPP. At birth, the piglets were weighed, identified and randomly distributed. Body weights were also measured on days 7, 14 and 19. Blood samples were collected to measure the level of urea, total protein (TP), albumin (AB) and globulin (GB). At weaning, 70 piglets from each treatment were distributed in five groups (replicates) of 14 piglets (seven males and seven females). Weights (animals and feed intake) were taken at post-weaning and at each feed change (days 14, 28 and 42 of raising). During the first two weeks of lactation, there were no effects of the treatments for the all evaluated variables. In the third week, TC piglets had higher serum levels of TP and GB, but lower WG than did control piglets. There was no effect of treatments on WG during the entire suckling period. There were no residual effects on nursery phase performance; however, treated piglets had less need for medications. SDPP supplementation did not influence zootechnical performance in the first two weeks or during the entire suckling period. The TC group had higher globulin levels than did the TA group. In the weaning phase, there were no effects on performance; however, there was a higher incidence of diseased animals in the TA group. Resumen: Este estudio fue diseñado para evaluar si la suplementación de lechones con plasma porcino secado por atomización (PPSA) el día del nacimiento, tiene un efecto positivo sobre el metabolismo de las proteínas y el aumento de peso (AP) en lechones lactantes, así como el rendimiento en la fase de cría. Seleccionamos 30 camadas de marranas al menos un par de lechones para cada tratamiento: TA = control sin PPSA, TB = administración oral de 10 g de PPSA y TC = 20 g de PPSA. Al nacer, los lechones fueron pesados, identificados y distribuidos al azar. Los pesos corporales también se midieron los días 7, 14 y 19. Se recogieron muestras de sangre para medir el nivel de urea, proteína total (PT), albúmina (AB) y globulina (GB). Al destete, se distribuyeron 70 lechones de cada tratamiento en cinco grupos (réplicas) de 14 lechones (siete machos y siete hembras). Los pesos (animales y consumo de alimento) se tomaron después del destete y en cada cambio de alimento (días 14, 28 y 42 de crianza). Durante las primeras dos semanas de lactancia, no hubo efectos de los tratamientos para todas las variables evaluadas. En la tercera semana, los lechones TC tenían niveles séricos más altos de TP y GB, pero un AP más bajo que los lechones de control. No hubo efecto de los tratamientos sobre el AP durante todo el período de lactancia. No hubo efectos residuales en el rendimiento de la fase de vivero; sin embargo, los lechones tratados tenían menos necesidad de medicamentos. La suplementación con SDPP no influyó en el rendimiento zootécnico en las primeras dos semanas o durante todo el período de lactancia. El grupo TC tenía niveles de globulina más altos que el grupo TA. En la fase de destete, no hubo efectos en el rendimiento; sin embargo, hubo una mayor incidencia de animales enfermos en el grupo TA

Recursion relations for Clebsch-Gordan coefficients of Uq_{q}(su2_{2}) and Uq_{q}(su1,1_{1,1})

International audienceWe report in this article three- and four-term recursion relations for Clebsch-Gordan coefficients of the quantum algebras U_q(su_2) and U_q(su_{1,1}). These relations were obtained by exploiting the complementarity of three quantum algebras in a q-deformation of sp(8, \gr)