Some results on the Krein parameters of an association scheme

We consider association schemes with d classes and the underlying Bose- Mesner algebra, A. Then, by taking into account the relationship between the Hadamard and the Kronecker products of matrices and making use of some matrix techniques over the idempotents of the unique basis of minimal orthogonal idempotents of A , we prove some results over the Krein parameters of an association scheme

Late-Time Tails of Wave Propagation in Higher Dimensional Spacetimes

We study the late-time tails appearing in the propagation of massless fields (scalar, electromagnetic and gravitational) in the vicinities of a D-dimensional Schwarzschild black hole. We find that at late times the fields always exhibit a power-law falloff, but the power-law is highly sensitive to the dimensionality of the spacetime. Accordingly, for odd D>3 we find that the field behaves as t^[-(2l+D-2)] at late times, where l is the angular index determining the angular dependence of the field. This behavior is entirely due to D being odd, it does not depend on the presence of a black hole in the spacetime. Indeed this tails is already present in the flat space Green's function. On the other hand, for even D>4 the field decays as t^[-(2l+3D-8)], and this time there is no contribution from the flat background. This power-law is entirely due to the presence of the black hole. The D=4 case is special and exhibits, as is well known, the t^[-(2l+3)] behavior. In the extra dimensional scenario for our Universe, our results are strictly correct if the extra dimensions are infinite, but also give a good description of the late time behaviour of any field if the large extra dimensions are large enough.Comment: 6 pages, 3 figures, RevTeX4. Version to appear in Rapid Communications of Physical Review

Neuroendocrine Pathways Mediating Nutritional Acceleration of Puberty: Insights from Ruminant Models

The pubertal process is characterized by an activation of physiological events within the hypothalamic-adenohypophyseal–gonadal axis which culminate in reproductive competence. Excessive weight gain and adiposity during the juvenile period is associated with accelerated onset of puberty in females. The mechanisms and pathways by which excess energy balance advances puberty are unclear, but appear to involve an early escape from estradiol negative feedback and early initiation of high-frequency episodic gonadotropin-releasing hormone (GnRH) secretion. Hypothalamic neurons, particularly neuropeptide Y and proopiomelanocortin neurons are likely important components of the pathway sensing and transmitting metabolic information to the control of GnRH secretion. Kisspeptin neurons may also have a role as effector neurons integrating metabolic and gonadal steroid feedback effects on GnRH secretion at the time of puberty. Recent studies indicate that leptin-responsive neurons within the ventral premammillary nucleus play a critical role in pubertal progression and challenge the relevance of kisspeptin neurons in this process. Nevertheless, the nutritional control of puberty is likely to involve an integration of major sensor and effector pathways that interact with modulatory circuitries for a fine control of GnRH neuron function. In this review, observations made in ruminant species are emphasized for a comparative perspective

Quasinormal modes of Schwarzschild black holes in four and higher dimensions

We make a thorough investigation of the asymptotic quasinormal modes of the four and five-dimensional Schwarzschild black hole for scalar, electromagnetic and gravitational perturbations. Our numerical results give full support to all the analytical predictions by Motl and Neitzke, for the leading term. We also compute the first order corrections analytically, by extending to higher dimensions, previous work of Musiri and Siopsis, and find excellent agreement with the numerical results. For generic spacetime dimension number D the first-order corrections go as $\frac{1}{n^{(D-3)/(D-2)}}$. This means that there is a more rapid convergence to the asymptotic value for the five dimensional case than for the four dimensional case, as we also show numerically.Comment: 12 pages, 5 figures, RevTeX4. v2. Typos corrected, references adde

Nariai, Bertotti-Robinson and anti-Nariai solutions in higher dimensions

We find all the higher dimensional solutions of the Einstein-Maxwell theory that are the topological product of two manifolds of constant curvature. These solutions include the higher dimensional Nariai, Bertotti-Robinson and anti-Nariai solutions, and the anti-de Sitter Bertotti-Robinson solutions with toroidal and hyperbolic topology (Plebanski-Hacyan solutions). We give explicit results for any dimension D>3. These solutions are generated from the appropriate extremal limits of the higher dimensional near-extreme black holes in a de Sitter, and anti-de Sitter backgrounds. Thus, we also find the mass and the charge parameters of the higher dimensional extreme black holes as a function of the radius of the degenerate horizon.Comment: 10 pages, 11 figures, RevTeX4. References added. Published versio

Controle do ácaro da falsa ferrugem (Phyllocoptruta oleivora Ashm., 1879) por um juvenóide e outros defensivos agrícolas

In order to control the citrus rust mite on orange-trees a field experiment was carried out in Limeira, State of São Paulo, Brazil, an important citrus producing area. Treatments correspondend to a single application on 01/10/89 of: A) check; B) juvenoid flucycloxuron, 40 cm³; C) bromopropilate 65 cm³; D) quinomethionate + sulphur 200 cm³; E) quinomethionate + sulphur 250 cm³; F) fonnetanate 22,5 g; G) formetanate 31,5 g. The quantities are of commercial formulations in 100 liters of water. Each tree received 10 liters of the mixtures. Avaliations were made before spraying and 6, 20, 36, 50 and 68 days after the application. The most effective results in the last three avaliations were obtained with treatments F, G and C. Treatments D and E were effective only for 6 and 20 days and the juvenoid for 20, 36 and 50 days after spraying.Vários defensivos agrícolas, incluindo um juvenóide, foram aplicados contra o acaro da falsa ferrugem em pomar localizado em Limeira,SP, uma das principais áreas citrícolas do Brasil. Os tratamentos constaram de uma única aplicação, feita em 01/10/89. Tratamentos: A) testemunha; B) flucicloxurom (juvenóide) 40 cm³; C) bromopropilato 65 cm³; D) quinometionato + enxofre 200 cm³; E) quinometionato + enxofre 250 cm³; F) formetanato22,5 g; G) formetanato 31,5 g. As quantidades referem-se aos produtos comerciais para 100 litros de água. Cada laranjeira recebeu 10 litros de calda. Espalhante-adesivo: "Extravon" (25 cm³/100 litros). O delineamento estatístico feito foi de blocos ao acaso, com 4 repetições. Foram feitas 6 avaliações: 1 prévia e 5 após 06, 20, 36, 50 e 68 dias da aplicação. F, G e C foram os melhores tratamentos. D e E foram eficientes somente aos 06 e 20 dias e o juvenóide, aos 20, 36 e 50 dias

Ensaio de combate ao ácaro da leprose de citros Brevipalpus phoenicis (Geijskes, 1939) com novo juvenóide e outros acaricidas

A field test was carried out on adult orange trees sprayed with flucycloxuron, propargite and bromopropilate to check their efficiency in controlling leprosis mite. Treatments used were: A) check; B) flucycloxuron, 10g; C) flucycloxuron, 15g; D) flucycloxuron, 20g; E) flucycloxuron, 30g; F) propargite, 72g; G) bromopropilate, 37,5g. Quantities indicated are grams of active ingredients per 100 liters of water. Control evaluations were made 2 days before and 7, 20, 34 and 50 days after spraying. Treatments of propargite and bromopropilate turned out to be the most efficient. Treatments B, C, D, E were not efficient at all.Foi montado um ensaio visando conhecer a eficiência do flucicloxurom (juvenóide constituído de benzoil-fenil-uréia substituída), do propargite e do bromopropilato, no combate ao acaro da leprose (Brevipalpus phoenicis Geijskes, 1939). Os produtos foram empregados nas seguintes dosagens: A) testemunha; B) flucicloxurom, 10g; C) flucicloxurom, 15g; D) flucicloxurom, 20g; E) flucicloxurom, 30g; F) propargite, 72g; G) bromopropilato, 37,5g (tratamento padrão), sendo os valores supracitados quantidade de ingrediente ativo por 100 litros de calda. Foram aplicados 6 litros de calda por laranjeira, com pulverizador motorizado costal. Foram feitas 5 avaliações do combate: uma prévia (02 dias antes da pulverização) e quatro outras (07, 20, 34 e 50 dias pós-aplicação). A partir dos resultados obtidos, conclui-se que os tratamentos mais eficientes foram o propargite e o bromopropilato

Ácaro da leprose Bvevipalpus phoenicis (Geijskes, 1939): combate experimental em laranjeiras

In order to control the mite of leprosis B. phoeniois a field test was carried out in Piracicaba, State of São Paulo, Brazil, with the following treatments and active ingredients per 100 liters of water: A) check; B) clofentezine, 9.45g; C) clofentezine, 9.45g + multimethyl alkenols, 0.4g; D) quinomethionate, 25.0g; E) quinomethionate, 37.5g; F) pyrethroid RU-1000, 1.76g; G) pyrethroid RU-1000; 2.0g; H) dicofol, 37.0g (standard treatment). Each orange tree was sprayed with 6 liters of the product. Six evaluations were made: one 3 days before spraying and 5 post-treatment (5, 14, 18, 26 and 35 days after spraying. The best treatments were B, F, G and H.Com o objetivo de combater o ácaro da leprose foi montado um campo experimental com os seguintes tratamentos: A) testemunha; B) clofentezina, 9,45g; C) clofentezina, 9,45g + alquenóis multimetílicos, 0,4g; D) quinometionato, 25,Og; E) quinometionato, 37,5g; F) piretróide RU-1.000, l,76g; G) piretróide RU-1.0Q0, 2,0g; H) dicofol, 37,0g (tratamento padrão). As quantidades citadas são de ingredientes ativos em 1000 litros de calda (Tabela 1). Cada laranjeira foi pulverizada com 6 litros de calda, aplicada com pulverizador costal motorizado. Foram feitas 6 avaliações: a prévia (03 dias antes da pulverização) e 5 pos-aplicaçao (05, 14, 18, 26 e 35 dias após a aplicação). Pela análise dos resultados obtidos verifica-se que os tratamentos B, F, G e H. foram os mais eficientes. Os resultados da redução real podem ser observados na Tabela 2