555 research outputs found
Study of complexation capacity and its relationship with some environmental variables in five reservoirs of the Tiete river system
The copper and cadmium complexation properties in natural sediment suspensions of reservoirs of the Tiete River were studied using the solid membrane copper and cadmium ion-selective electrodes. The complexation and the average conditional stability constants were determined under equilibrium conditions at pH=6.00 +/- 0.05 in a medium of 1.0 mol L-1 sodium nitrate, using the Scatchard method. The copper and cadmium electrodes presented Nernstian behavior from 1 X 10(-6) to 1 x 10(-1) mol L-1 of total metal concentration. Scatchard graphs suggest two classes of binding sites for both metals. A multivariate study was done to correlate the reservoirs and the variables: complexation properties, size, total organic carbon, volatile acid sulfide, E-H and pH.3071505151
Observation of the thermal Casimir force
Quantum theory predicts the existence of the Casimir force between
macroscopic bodies, due to the zero-point energy of electromagnetic field modes
around them. This quantum fluctuation-induced force has been experimentally
observed for metallic and semiconducting bodies, although the measurements to
date have been unable to clearly settle the question of the correct
low-frequency form of the dielectric constant dispersion (the Drude model or
the plasma model) to be used for calculating the Casimir forces. At finite
temperature a thermal Casimir force, due to thermal, rather than quantum,
fluctuations of the electromagnetic field, has been theoretically predicted
long ago. Here we report the experimental observation of the thermal Casimir
force between two gold plates. We measured the attractive force between a flat
and a spherical plate for separations between 0.7 m and 7 m. An
electrostatic force caused by potential patches on the plates' surfaces is
included in the analysis. The experimental results are in excellent agreement
(reduced of 1.04) with the Casimir force calculated using the Drude
model, including the T=300 K thermal force, which dominates over the quantum
fluctuation-induced force at separations greater than 3 m. The plasma
model result is excluded in the measured separation range.Comment: 6 page
High temperatures and absence of light affect the hatching of resting eggs of Daphnia in the tropics
Dinâmica populacional de Bemisia tabaci biótipo B em tomate monocultivo e consorciado com coentro sob cultivo orgânico e convencional.
A mosca-branca Bemisia tabaci BiĂłtipo B (Hemiptera:
Aleyrodidae), Ă© um herbĂvoro de difĂcil controle devido Ă alta plasticidade genotĂpica da espĂ©cie. No tomateiro pode causar danos severos principalmente pela transmissĂŁo de diversas viroses. O manejo do sistema de produção e o consĂłrcio de culturas podem ter um efeito direto nas populações desse herbĂvoro, sem que seja necessária a aplicação de inseticidas. Avaliou-se a influĂŞncia dos sistemas de produção orgânico e convencional e o consĂłrcio tomate-coentro na dinâmica populacional da mosca-branca no campo experimental da Embrapa Hortaliças, de maio a setembro/06. O monitoramento dos adultos da mosca-branca e de seus inimigos naturais foi realizado utilizando-se armadilhas adesivas amarelas fixadas nas bordas e no interior das parcelas experimentais e a amostragem de ninfas foi realizada por observação direta das folhas de tomate no campo. Embora as populações ao redor dos diferentes tratamentos fossem equivalentes, a abundância de adultos de mosca-branca foi significativamente menor nas parcelas de tomate consorciado com coentro, tanto no sistema convencional como orgânico. Apenas o consĂłrcio tomatecoentro em sistema orgânico apresentou redução significativa na quantidade de ninfas por planta em relação aos demais tratamentos. Os inimigos naturais foram significativamente mais abundantes em sistema orgânico e foi verificada uma correlação negativa da abundância
dos inimigos naturais e a quantidade de ninfas por planta. A associação tomate-coentro e o manejo orgânico do agroecossistema favoreceram ao controle biológico natural da mosca-branca
Behavioral responses to injury and death in wild Barbary macaques (Macaca sylvanus)
The wounding or death of a conspecific has been shown to elicit varied behavioral responses throughout thanatology. Recently, a number of reports have presented contentious evidence of epimeletic behavior towards the dying and dead among non-human animals, a behavioral trait previously considered uniquely human. Here, we report on the behavioral responses of Barbary macaques, a social, non-human primate, to the deaths of four group members (one high-ranking adult female, one high-ranking adult male, one juvenile male, and one female infant), all caused by road traffic accidents. Responses appeared to vary based on the nature of the death (protracted or instant) and the age class of the deceased. Responses included several behaviors with potential adaptive explanations or consequences. These included exploration, caretaking (guarding, carrying, and grooming), and proximity to wounded individuals or corpses, and immediate as well as longer-lasting distress behaviors from other group members following death, all of which have been reported in other non-human primate species. These observations add to a growing body of comparative evolutionary analysis of primate thanatology and help to highlight the multifaceted impacts of human-induced fatalities on an endangered and socially complex primate. © 2016, Japan Monkey Centre and Springer Japan
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