Mechanics of adhesive contact on a power-law graded elastic half-space

We consider adhesive contact between a rigid sphere of radius R and a graded elastic half-space with Young's modulus varying with depth according to a power law E = E-0(z/c(0))(k) (0 < k < 1) while Poisson's ratio v remaining a constant. Closed-form analytical solutions are established for the critical force, the critical radius of contact area and the critical interfacial stress at pull-off. We highlight that the pull-off force has a simple solution of P-cr= -(k+3)pi R Delta gamma/2 where Delta gamma is the work of adhesion and make further discussions with respect to three interesting limits: the classical JKR solution when k = 0, the Gibson solid when k --> 1 and v = 0.5, and the strength limit in which the interfacial stress reaches the theoretical strength of adhesion at pull-off. (C) 2009 Elsevier Ltd. All rights reserved.

Export potential of ornamental live fishes in Nigeria

Nigeria is blessed with an abundant variety of fish species, some of which have been exported over the years. These fish species are taken either from the wild or cultured. Large quantities of fishes and fishery products are exported from Nigeria in different forms and which have been sources of foreign exchange earnings for the Country. An estimate value of exports in the fishery sub-sector stood at approximately U.S. $48.212,070 for shrimps/sole fish/cuttlefish/crabs and over U.S.$500,000 for ornamental live fishes

The survival and growth of hybrid Clarias gariepinus and Heterotis longifilis fed with live and frozen Dapthnids

Six glass tanks, each containing dechlorinated tap water and stocked with 3-day-old Heterobranchus, larvae hybrid between, Heterobranchus longifilis (male and Clarias gariepinus (female) were administered two types of feeding trials viz: live and frozen Dapthnids. Each treatment was replicated three times. The larvae were each fed approximately 50 Dapthnids per feeding time for fifteen days. Morphometric measurements of weigh and total length were taken before and after the experiment, and water quality parameters were monitored throughout the experimental period. At the end of the experiment, fish larvae fed frozen, Dapthnids, showed higher survival rate than Heterobranchus fed live Dapthnids. Even though the statistical analysis revealed that there was no significant difference (P>0.05) in survival. However, the Heteroclarias fed live dapthnids performed better in terms of growth rate than Heteroclarias fed frozen dapthnids. The statistical analysis did not show significant difference (P>0.05) between the final length and weight of two treatments. Heteroclarias fed live dapthnids had higher length and weight than Heteroclarias fed frozen dapthnids. It was therefore concluded that based on this experiment there is the likelihood that frozen zooplankton (Daphnids) do not encourage growth of Heteroclarias, but improves its survival. However, it's suggested that frozen zooplankton can be used to supplement live zooplankton in situation of sacrcity

The impact of varying nutrient regimes in earthen freshwater ponds on the comparative ecology of diurnally occurring candidate live feeds

The daytime composition and relative abundance of zooplankton species were studied in three treatments of two replicate earthen ponds each with nutrient sources and water replenishment regimes. Treatment -A (200m super(2) surface area supplied 900kgha super(-1) pig manure only). Treatment -B (200m super(2) surface area supplied 70kgha super(-1) month super(-1) pig manure, 50kgha super(-1) month super(-1) N.P.K. [15:15:15] and 30kgha super(-1) month super(-1) Urea) and Treatment-C (1500m2 surface area supplied 1150kgha super(-1) month super(-1) commercial grade 40% crude protein compounded feed). Water replenishment for Treatment A was daily tidal deluge from the New Calabar River while that for treatment B and C was from column-well and occasional rains. No zooplankton species were recovered from the pig-manure only treatment (A) while only Diffugia constricta and Difflugia urceolata were the two protozoans that occurred together in treatments B (combined fertilization) and C (compounded feed only) in contrast, Difflugia acuminate and three rotifers, Collurella uncinata, Diurella stylata and Keratella quadrata occurred only treatment B. similarly, Arcella arenaria, Arcella costata, Centropyxis aculeate, Difflugia pyriformis, Branchionus calyciflorus, Lepadella patella, Polyarthra trigla and Onchocanmptus mohammedi were recovered from treatment C. Arcella costata was the most abundant zooplankton in the entire experiment, while Arcella arenaria was very abundant in treatment C, Collurella uncinata was very abundant in treatment B. The inference is that combined fertilization of earthen freshwater ponds tend to be more suitable for the culture of rotifers such as Brachionus calyciflorus, popular in fish larva nursery, while those supplied compounded feed could be used to produce protozoans where desirable

Sub-half-wavelength atom localization via two standing-wave fields

We propose a scheme for sub-half-wavelength atom localization in a four-level ladder-type atomic system, which is coupled by two classical standing-wave fields. We find that one of the standing-wave fields can help in enhancing the localization precision, and the other is of crucial importance in increasing the detecting probability and leading sub-half-wavelength localization.

Part I - The radiation of elastic waves from a spherical cavity in a half space. Part II - Precision determination of focal depths and epicenters of earthquakes.

Part I: The dynamic response of an elastic half space to an explosion in a buried spherical cavity is investigated by two methods. The first is implicit, and the final expressions for the displacements at the free surface are given as a series of spherical wave functions whose coefficients are solutions of an infinite set of linear equations. The second method is based on Schwarz's technique to solve boundary value problems, and leads to an iterative solution, starting with the known expression for the point source in a half space as first term. The iterative series is transformed into a system of two integral equations, and into an equivalent set of linear equations. In this way, a dual interpretation of the physical phenomena is achieved. The systems are treated numerically and the Rayleigh wave part of the displacements is given in the frequency domain. Several comparisons with simpler cases are analyzed to show the effect of the cavity radius-depth ratio on the spectra of the displacements.

Part II: A high speed, large capacity, hypocenter location program has been written for an IBM 7094 computer. Important modifications to the standard method of least squares have been incorporated in it. Among them are a new way to obtain the depth of shocks from the normal equations, and the computation of variable travel times for the local shocks in order to account automatically for crustal variations. The multiregional travel times, largely based upon the investigations of the United States Geological Survey, are confronted with actual traverses to test their validity.

It is shown that several crustal phases provide control enough to obtain good solutions in depth for nuclear explosions, though not all the recording stations are in the region where crustal corrections are considered. The use of the European travel times, to locate the French nuclear explosion of May 1962 in the Sahara, proved to be more adequate than previous work.

A simpler program, with manual crustal corrections, is used to process the Kern County series of aftershocks, and a clearer picture of tectonic mechanism of the White Wolf fault is obtained.

Shocks in the California region are processed automatically and statistical frequency-depth and energy depth curves are discussed in relation to the tectonics of the area.

The radio is dead. Long live the radio : Leioan, 2011ko azaroaren 24 eta 25ean egindako Ikus-Entzunezko Komunikazioa eta Publizitateko Nazioarteko I. Kongresuaren aktak

A menudo, el deslumbramiento de los nuevos medios impide el reconocimiento debido a otras alternativas de comunicación social que, de manera persistente y discreta, han llegado a confundirse con nuestra propia vida. Es el caso de este medio invisible, que bien se merecía un congreso dedicado a la mejor radio y a uno de sus mayores inspiradores, Bertolt Brecht, quien ochenta años atrás imaginó una radio interactiva cuando no existía la tecnología necesaria para hacer realidad su sueño. Hoy como ayer, las voces comunicantes de la radio cuentan mil y una historias que los oyentes siguen como si les fuera la vida en ello. Quizá la radio no esté a la cabeza de las industrias creativas, pero su magia sigue desatando la imaginación y la creatividad de las audiencias. Es por eso, y por su cercanía, que da tanta confianza y es tan querida. Nada más lejos de nuestra intención que la autocomplacencia, un virus tanto o más peligroso que el ruido y la cacofonía radiofónica, que de todo hay en el dial. Los participantes en este encuentro nos hemos conjurado a favor de una radio abierta; hecha con cabeza y corazón, como la vida misma; y más acogedora con los jóvenes creadores, que no lo saben todo de la radio, pero, por eso mismo, están mejor preparados para llevar el ritmo que bailan las neuronas de las nuevas audiencias. Una radio que da la palabra a la gente, sabe escuchar, y no se agota en el ejercicio inútil de escucharse a sí misma.

Programa Bairro-Escola de Nova Iguaçu: diretrizes e caracterísiticas desta política educacional na gestão e organização curricular da Rede Municipal de Ensino

Esta pesquisa é fundamentada e metodologicamente construída objetivando descrever e analisar o que e como é o Programa Bairro-Escola de Nova Iguaçu, implementado como política educacional, em 2006, para organização curricular da Rede Municipal de Ensino. O foco deste estudo qualitativo está centrado na identificação das principais diretrizes e características produzidas por essa política curricular no/para o desenvolvimento da gestão democrática e na melhoria da prática educativa. Para tanto, a metodologia utilizada para a elaboração deste trabalho foi a abordagem qualitativa, a investigação teórica de eixos temáticos e o estudo de caso do significado do Programa Bairro-Escola para os sujeitos que o vivenciam em Nova Iguaçu, abordando especificamente quais são as principais características que o Programa tem produzido, até então, na gestão macro e micro educacional, na prática educativa e na relação entre ambas as práticas, sob a ótica dos sujeitos que o vivenciam no seu cotidiano de desenvolvimento. Para tanto, este estudo de caso de cunho descritivo-analítico utilizou como campo de investigação duas escolas municipais (situadas em bairros geograficamente distantes) como amostragem e a Secretaria Municipal de Educação de Nova Iguaçu para a obtenção, por meio de entrevistas semiestruturadas (realizadas no segundo semestre de 2011), de informações que "respondessem" aos objetivos desta pesquisa. No entanto, os sujeitos escolhidos para serem entrevistados foram: (um) representante da Secretaria Municipal de Educação de Nova Iguaçu, (dois) diretores, (dois) coordenadores, (dois) orientadores, (dois) professores, (dois) estagiários, (dois) agentes comunitários, (dois) pais de alunos e (dois) alunos, os quais relataram nas entrevistas que o Programa Bairro-Escola iguaçuano, apesar de ser uma política educacional ainda recente, tem contribuído para a melhoria da prática educativa, na medida em que as oportunidades educativas foram ampliadas com a implantação do Horário Integral através das oficinas fixas de aprendizagem, esporte, cultura, informática, entre outras experiências socioeducativas desenvolvidas no âmbito escolar ou em ambientes parceiros nas comunidades do entorno das escolas. E na gestão educacional através da conquista da implementação do conselho escolar, o qual tem possibilitado uma gestão mais participativa e mais autônoma nas escolas. Mas expuseram também que, para um "melhor rendimento", o Bairro-Escola, aqui, ainda carece de variados recursos infraestruturais (recursos de natureza física, humana ou pedagógica) e de mais estratégias que dinamizem a gestão mais participativa, o envolvimento comunitário e o reconhecimento do Programa.

A versão portuguesa do mito de Édipo

Esta dissertação visa a leitura do texto dramático António Marinheiro (O Édipo de Alfama) de Bernardo Santareno, tendo como ponto de partida Édipo Rei de Sófocles. Os fundamentos teóricos para a interpretação desses textos são a obra freudiana e o ensino de Jacques Lacan. Santareno retira as suas personagens do interior das muralhas de Tebas para colocá-las em Alfama, bairro de Lisboa, na segunda metade do século XX. Nesse novo cenário, o fado, o vinho e a taberna compõem os costumes tipicamente portugueses. Escolhemos dois filmes, Édipo Rei de Pier Paolo Pasolini e Incêndios de Denis Villeneuve, para fazer uma leitura comparativa com as peças de Sófocles e de Bernardo Santareno. O início do filme de Pasolini ocorre em uma cidade pequena ao norte da Itália e depois se transfere para a Grécia antiga onde se passa a tragédia de Sófocles. Incêndios é uma adaptação da peça do libanês Wadji Mouawad e retrata a guerra civil do Líbano, a intolerância religiosa, estupro, incesto e genocídio

Calibration method for a photoelastic modulator with a peak retardation of less than a half-wavelength

A new calibration method for a photoelastic modulator is proposed. The calibration includes a coarse calibration and a fine calibration. In the coarse calibration, the peak retardation of the photoelastic modulator is set near 1.841 rad. In the fine calibration, the value of the zeroth Bessel function is obtained. The zeroth Bessel function is approximated as a linear equation to directly calculate the peak retardation. In experiments, the usefulness of the calibration method is verified and the calibration error is less than 0.014 rad. The calibration is immune to the intensity fluctuation of the light source and independent of the circuit parameters. The method specially suits the calibration of a photoelastic modulator with a peak retardation of less than a half-wavelength. (c) 2007 Optical Society of America.

Susceptibilidade de pacus, Piaractus mesopotamicus (Holmberg, 1887), sob hipoxia aos agrotóxicos organofosforados

A ação inibitória dos organofosforados sobre as esterases, por ser específica, pode ser empregada como um eficiente biomarcador da exposição de seres vivos aos organofosforados. A inibição da acetilcolinesterase (AChE; EC 3.1.1.7) provoca acúmulo do neurotransmissor acetilcolina nas fendas sinápticas colinérgicas, o que pode resultar na morte do indivíduo. Outra atividade também afetada por organofosforados é a da enzima carboxilesterase (CarbE; EC 3.1.1.1). CarbE estão envolvidas na fase I da biotransformação de xenobióticos e atuam como captadoras (scavengers) de organofosfatos, incluindo os formados pela biotransformação dos organofosforados. As CarbE estudadas até hoje se ligam com maior velocidade aos organofosfatos do que as colinesterases. Por isto se admite que CarbE possam diminuir, por captação estequiométrica, a ligação tóxica de moléculas de organofosfatos às acetilcolinesterases das sinapses colinérgicas e das placas motoras dos músculos. Experimentos realizados em nosso laboratório mostraram que a atividade da CarbE está aproximadamente 50% menor no soro e no fígado de pacus submetidos à hipoxia. Por causa disso, em razão de uma possível diminuição da capacidade captadora da CarbE, decidimos verificar se o pacu em hipoxia seria mais sensível aos agrotóxicos organofosforados. Para este propósito foram colocados seis pacus divididos em dois tanques. No primeiro tanque, os animais foram submetidos a 24 horas de hipoxia seguidos por mais 4 horas de exposição ao organofosforado metilparation em duas concentrações diferentes (0,02 ou 0,01 mg / L). No segundo tanque os animais permaneceram em normoxia durante o mesmo período de 24 horas e depois foram expostos ao metilparation como no primeiro tanque. As atividades da AChE ensaiada com acetiltiocolina, a da butirilcolinesterase (BChE) ensaiada com butiriltiocolina e a da CarbE ensaiada com p-nitrofenilacetato foram avaliadas no soro, fígado, cérebro, músculo e coração dos pacus. Houve redução de aproximadamente 35% da atividade de CarbE no soro dos pacus submetidos a 24 horas de hipoxia. Uma queda de 85% na atividade de CarbE do soro foi observada nos animais que sofreram hipoxia e subsequente exposição a 0,02 mg de metilparation por litro. Com metilparation a 0,01 mg/L a diminuição observada foi de 48,2%. No músculo dos pacus expostos a 0,02 mg/L, as atividades de AChE e BChE cairam pela metade quando os mesmos foram submetidos à hipoxia quando comparados a animais que permaneceram em normoxia. Nos diversos tecidos dos pacus expostos a 0,01 mg/L de metilparation não observamos diferenças significativas nas atividades de AChE, BChE ou CarbE. Concluímos que a duplicação da concentração de metilparation de 0,01 para 0,02 mg/L levou à atividade residual de CarbE do soro de 51,8% para 15%. A ausência de mudanças nas atividades das esterases dos tecidos de animais expostos a 0,01 mg/L entre os grupos hipoxia e normoxia deve ter ocorrido porque a concentração de organofosforado não foi suficiente para superar a primeira barreira de proteção das esterases séricas e atingir os tecidos. Mas, no experimento com 0,02 mg/L de metilparation, as inibições de AChE e de BChE no músculo dos animais em hipoxia podem ser explicadas pela diminuição da atividade de CarbE do soro dos pacus.

How fresh is too fresh?: the live reef food fish trade in eastern Indonesia

Although the live reef food fish trade has become an increasingly "hot" topic in the environmental press in recent months, many of the sources reporting on this practice have tended to focus on issues related to the rampant use of sodium cyanide in the trade, rather than the more pressing matter of the looming potential for overexploitation engendered by this practice. Presented in this article is a brief overview of the live reef food fish trade as it is practiced in eastern Indonesia covering the methods used and economics, geographic extent and numerous deleterious effects of the fishery.

The relationship of shell dimensions and shell volume to live weight and soft tissue weight in the mangrove clam, Polymesoda erosa (Solander, 1786) from northern Australia

Shell dimensions (length, height, width) and shell volume were evaluated as estimators of growth for Polymesoda erosa in northern Australia. Each parameter was a good estimator when applied to live weight (r2 values of 76-96 percent), but not to soft tissue weight (wet, dry, or ash-free dry weight) (r2 values of 13-32 percent). The b value for shell volume to weight relationship of clams collected during the dry season (June to October) was signifi cantly different than for those collected in the wet season (February to April).

The half-lives of biological activity of some pesticides in water

In the absence of analytical methods, the half-lives of biological activity of pesticides can be estimated by bioassays. To determine the half-lives of biological acivity of pesticides to fish, static bioassays were conducted in the laboratory with ten different formulations of pesticides using Labeo rohita as a bio-indicator. The half-lives of biological activity for ten different pesticides in soft water at pH 7.5 and 27°C, ranged from 4.6 days to 11.8 days. The half-life of biological activity of Sumithion 50% EC was only 4.6 days. In contrast, Dimecron 50% EC degraded very slowly and its half-life of biological activity on L. rohita was about 11.8 days. Sumithion 50% EC, Padan 50% SP, EPN 45% EC, Diazinon 40% EC and Diazinon 10 G degraded in less than five to seven days indicating that these pesticides are desirable for rice-fish culture. Contamination by pesticides with long-term residual toxicity in waters may eventually cause high levels of fish mortality.

A taste for live fish: Hong Kong's live reef fish market

This paper provides an overview of the live reef fish market in Hong Kong, which accounted for about 15,000 t/yr (US$345 million) of live fish imports in the mid-1990s. The live fish trade has spawned a number of management concerns, including overfishing of highly-valued species, use of destructive fishing techniques and human health risks. Recent actions by the Hong Kong government in response to these concerns are reported and possible region-wide initiatives are briefly discussed in this paper.