On Yukawa quasi-unification with mu<0

Although recent data on the muon anomalous magnetic moment strongly disfavor the constrained minimal supersymmetric standard model with mu<0, they cannot exclude it because of theoretical ambiguities. We consider this model supplemented by a Yukawa quasi-unification condition which allows an acceptable b-quark mass. We find that the cosmological upper bound on the lightest sparticle relic abundance is incompatible with the data on the branching ratio of b-->s gamma, which is evaluated by including all the next-to-leading order corrections. Thus, this scheme is not viable.Comment: 4 pages including 3 figures, Revte

Particle Physics Approach to Dark Matter

We review the main proposals of particle physics for the composition of the cold dark matter in the universe. Strong axion contribution to cold dark matter is not favored if the Peccei-Quinn field emerges with non-zero value at the end of inflation and the inflationary scale is superheavy since, under these circumstances, it leads to unacceptably large isocurvature perturbations. The lightest neutralino is the most popular candidate constituent of cold dark matter. Its relic abundance in the constrained minimal supersymmetric standard model can be reduced to acceptable values by pole annihilation of neutralinos or neutralino-stau coannihilation. Axinos can also contribute to cold dark matter provided that the reheat temperature is adequately low. Gravitinos can constitute the cold dark matter only in limited regions of the parameter space. We present a supersymmetric grand unified model leading to violation of Yukawa unification and, thus, allowing an acceptable b-quark mass within the constrained minimal supersymmetric standard model with mu>0. The model possesses a wide range of parameters consistent with the data on the cold dark matter abundance as well as other phenomenological constraints. Also, it leads to a new version of shifted hybrid inflation.Comment: 32 pages including 6 figures, uses svmult.cls, some clarifications added, lectures given at the Third Aegean Summer School "The Invisible Universe: Dark Matter and Dark Energy", 26 September-1 October 2005, Karfas, Island of Chios, Greece (to appear in the proceedings

Curva crítica de diluição do nitrogênio para a cultura do melão Nitrogen critical dilution curve for the muskmelon crop

O objetivo do trabalho foi ajustar a curva crítica de diluição do nitrogênio da cultura do melão. O experimento foi conduzido em ambiente protegido na Universidade Federal de Santa Maria (UFSM), entre agosto de 2004 e janeiro de 2005. As mudas do híbrido Magellan foram plantadas em sacolas de polietileno contendo 4,5dm-3 de substrato comercial (Plantmax PXT®), na densidade de 3,3 plantas m-2 e fertirrigadas com solução nutritiva completa. As plantas foram conduzidas verticalmente com uma haste, deixando-se no máximo dois frutos por planta e foram podadas ao atingir a altura de 2m. Os tratamentos foram constituídos por concentrações de nitrogênio na solução nutritiva de 8; 11, 14; 17 e 20mmol L-1. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições. Quatro plantas de cada tratamento foram coletadas semanalmente entre os 33 e 99 dias após o plantio para determinar o acúmulo de matéria seca (MS) e o teor de N nas folhas, haste e frutos. Foi constatada a diluição da concentração de N na matéria seca em todos os tratamentos e os dados ajustaram-se ao modelo potencial %N = aMS-b descrito na literatura. A curva crítica de diluição do N foi ajustada, com coeficientes a e b iguais a 5,16 e 0,63, respectivamente. Esse modelo poderá ser usado para estimar a quantidade de N extraída no decorrer do ciclo de crescimento e desenvolvimento dessa cultura, com base na análise do teor desse nutriente nas folhas.<br>The research was carried out to adjust the nitrogen critical dilution curve for the muskmelon crop, to be used in fertilization practices for this crop. The experiment was conducted in a greenhouse at Universidade Federal de Santa Maria, from August to January, 2005. Plantlets of the hybrid Magellan was grown in polyethylene bags with 4.5dm3 of the commercial substrate Plantmax PXT®, in a plant density of 3.3plants m-2, and fertigated with a complete nutrient solution. Plants were vertically trained with one stem and no more than two fruits per plant, and the main stem was cut at 2m height. Treatments were N concentrations in the nutrient solution of 8, 11, 14, 17, and 20mmol L-1, in a randomized experimental design with four replications. Four plants of each treatment were harvested at weekly intervals between 33 and 99 days after planting to determine dry mass (DM) accumulation and N concentration in leaves, stem and fruits. The N dilution in plant dry mass was confirmed in all treatments and data fitted the potential model %N = aMS-b described in the literature. The N dilution curve was adjusted, with values of 5.16 and 0.63 for a and b coefficients, respectively. This model could be used to estimate the N quantity absorbed during growth and development of this crop, based on the analysis of this element on leaf tissues

The mediating role of psychological need satisfaction in relationships between types of passion for sport and athlete burnout

Research indicates that obsessive and harmonious passion can explain variability in burnout through various mediating processes (e.g., Vallerand, Paquet, Phillippe, & Charest, 2010). The current study extended previous research (Curran, Appleton, Hill, & Hall, 2011; Gustafsson, Hassmén, & Hassmén, 2011) by testing a model in which the effects of passion for sport on athlete burnout were mediated by psychological need satisfaction. One hundred and seventy-three academy soccer players completed self-report measures of passion for sport, psychological need satisfaction, and athlete burnout. Results indicated that psychological need satisfaction mediated the relationship between harmonious passion and athlete burnout but not obsessive passion and athlete burnout. The findings indicate that the inverse relationship between harmonious passion and burnout can be explained by higher levels of psychological need satisfaction. However, this was not the case for obsessive passion, which was not associated with psychological need satisfaction or most symptoms of athlete burnout