Entropy of bosonic open string and boundary conditions

The entropy of the states associated to the solutions of the equations of motion of the bosonic open string with combinations of Neumann and Dirichlet boundary conditions is given. Also, the entropy of the string in the states \A(i)] = alpha(-1)(i)\0] and \phi(a)]= alpha(-1)(a)\0] that describe the massless fields on the world-volume of the Dp-brane is computed. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Water deficit affects photosynthetic induction in Bauhinia forficata Link (Fabaceae) and Esenbeckia leiocarpa Engl. (Rutaceae) growing in understorey and gap conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of daily changes in environmental factors on the abundance and richness of Odonata

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da estrutura do hábitat sobre a ictiofauna de um riacho em uma micro-bacia de pastagem, São Paulo, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oviposition preference of Bemisia tabaci (Genn.) biotype B (Homoptera: Aleyrodidae) for bean genotypes containing arcelin in the seeds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antibiosis effects of wild bean lines containing arcelin on Bemisia tabaci (Genn.) biotype B (Homoptera: Aleyrodidae)

A biologia de Bemisia tabaci biótipo B (Genn.) foi avaliada em genótipos de feijoeiro (Phaseolus vulgaris L.) que contêm arcelina em suas sementes. Foi também realizada análise bioquímica de proteínas, em sementes e em folhas dos genótipos de feijoeiro, a fim de verificar se haveria traços de arcelina nas folhas dos materiais a serem avaliados. Os testes foram conduzidos em condições de casa de vegetação, nas épocas das águas e da seca, em dois anos consecutivos, com os seguintes genótipos: ARC 3s, ARC 5s (genótipos selvagens portadores de arcelina); ARC 1, ARC 2, ARC 3, ARC 4 (linhagens quase-isogênicas portadoras de arcelina - Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)), Porrillo 70, Bolinha e IAPAR MD 808 (genótipos sem arcelina). Os genótipos selvagens, ARC 3s e ARC 5s, apresentaram altos níveis de antibiose, com ênfase para o ARC 5s (as ninfas tiveram alta mortalidade, em torno de 90%). O prolongamento do ciclo de desenvolvimento dos insetos provenientes do genótipo ARC 5s podem sugerir uma resistência do tipo antibiose e/ou não-preferência para alimentação. A resistência dos genótipos selvagens não está relacionada com a presença de arcelina nas sementes, já que nenhum traço dessa proteína foi encontrado nas folhas destes.

Power law distribution in education: Effect of economical, teaching, and study conditions in university entrance examination

We studied the statistical distribution of student's performance, which is measured through their marks, in university entrance examination (Vestibular) of UNESP (Universidade Estadual Paulista) with respect to (i) period of study - day versus night period (ii) teaching conditions - private versus public school (iii) economical conditions - high versus low family income. We observed long ubiquitous power law tails in physical and biological sciences in all cases. The mean value increases with better study conditions followed by better teaching and economical conditions. In humanities, the distribution is close to normal distribution with very small tail. This indicates that these power law tails in science subjects axe due to the nature of the subjects themselves. Further and better study, teaching and economical conditions axe more important for physical and biological sciences in comparison to humanities at this level of study. We explain these statistical distributions through Gradually Truncated Power law distributions. We discuss the possible reason for this peculiar behavior.

Precipitation chemistry and wet deposition in Kruger National Park, South Africa

The chemical composition, as well as the sources contributing to rainwater chemistry have been determined at Skukuza, in the Kruger National Park, South Africa. Major inorganic and organic ions were determined in 93 rainwater samples collected using an automated wet-only sampler from July 1999 to June 2002. The results indicate that the rain is acidic and the averaged precipitation pH was 4.72. This acidity results from a mixture of mineral acids (82%, of which 50% is H2SO4) and organic acids (18%). Most of the H2SO4 component can be attributed to the emissions of sulphur dioxide from the industrial region on the Highveld. The wet deposition of S and N is 5.9 kgS.ha(-1).yr(-1) and 2.8 kgN.ha(-1).yr(-1), respectively. The N deposition was mainly in the form of NH4+. Terrigenous, sea salt component, nitrogenous and anthropogenic pollutants have been identified as potential sources of chemical components in rainwater. The results are compared to observations from other African regions.

Psychophysical power functions for apparent area in perceptive, memory, and inference conditions for observers of different age groups

The purpose of this research was to verify the effect of age on the exponent of the power function in Perceptive, Memory, and Inference experimental conditions. In the Memory condition the intervals of 2 min., 8, 24, and 48 hr. and 1 wk. were used between acquisition of information and remembering. For each experimental condition the ages of observers ranged between 17 and 35 years (Group I), 40-55 years (Group II), and 60-77 years (Group III), and education ranged from high school to graduate school. The observers estimated the areas of the Brazilian states using the psychophysical method of magnitude estimation. No significant differences were obtained for Groups I, II, and III for each experimental condition, except in the Memory Condition with the 24-hr. interval. Analysis for experimental conditions and ages showed a significant difference between the Perceptive Condition and each of the others, but no difference between the Inference and Memory Conditions. These results indicated that in the remembering processes there is no loss of information as a function of age. From the small variability in the power function exponents for the three ages, we may assume that age could be related to amount of education of the observers, which suggests study is important.

A demonstration of dry and viscous damping of an oscillating pendulum

Damped oscillatory motion is one of the most widely studied movements in physics courses. Despite this fact, dry damped oscillatory motion is not commonly discussed in physics textbooks. In this work, we discuss the dry and viscous dampec pendulum, in a teaching experiment that can easily be performed by physics or engineering students.

Degradation of rice pesticides and their stability during storage of samples

Transformation of pesticides is directly related to the environmental conditions during application and transport of these compounds in the ecosystem. Rice fields include peculiar conditions, relatively high temperatures and wet conditions, leading to degradation processes, different from that observed in other agricultural systems. This article presents the degradation routes of some characteristic rice insecticides and herbicides under field conditions. A compilation of the pesticides that are usually applied during rice cultivation is included, with their main physico-chemical parameters. The stability of the pesticides by solid phase extraction systems during storage of rice samples is also discussed.

Study on the behavior of the Minimum quantity lubricant - MQL technique under different lubricating and cooling conditions when grinding ABNT 4340 steel

The behavior of the minimum quantity lubricant (MQL) technique was analyzed under different lubricating and cooling conditions when grinding ABNT 4340 steel. The comparative analysis of the residual stress values showed that residual compressive stresses were obtained under all the lubrication/cooling conditions and types of abrasive tools employed. The highest residual compressive stress obtained with the aluminum oxide grinding wheel with MQL under the condition of V= 30m/s for air and V= 40ml/h for lubricant was -376MPa against the -160MPa attained with conventional cooling, representing a 135% increase in residual compressive stress. The results show that method and quantity of lubricant and cooling are factors that influence the grinding process.