Efeito de pesticidas aos polinizadores do guaranazeiro: avaliação da toxicidade aguda de inseticidas às abelhas (Hymenoptera: Apidae).

Neste trabalho foi avaliada a sensibilidade da espécie de abelha Melipona seminigra, nativa da Amazônia, ao inseticida Parathion metil

Toxicidade aguda de Parathion Metil para Danio rerio (Teleostei, Cyprinidae), em condições tropicais.

Neste estudo a toxicidade de Parathion metil foi avaliada para Danio rerio, uma espécie de peixe usada como indicadora em ensaios toxicológicos

Magnetization reversal and anomalous coercive field temperature dependence in MnAs epilayers grown on GaAs(100) and GaAs(111)B

The magnetic properties of MnAs epilayers have been investigated for two different substrate orientations: GaAs(100) and GaAs(111). We have analyzed the magnetization reversal under magnetic field at low temperatures, determining the anisotropy of the films. The results, based on the shape of the magnetization loops, suggest a domain movement mechanism for both types of samples. The temperature dependence of the coercivity of the films has been also examined, displaying a generic anomalous reentrant behavior at T$>$200 K. This feature is independent of the substrate orientation and films thickness and may be associated to the appearance of new pinning centers due to the nucleation of the $\beta$-phase at high temperatures.Comment: 9 pages, 7 figure

Toxicidade aguda do herbicida Glifosato (Roundup) para Danio rerio (Teleostei, Cyprinidae), em condições tropicais.

Avaliou-se, neste estudo, o potencial toxicológico do herbicida Roundup para peixes

The effects of the insecticide lambda-Cyhalothrin on the earthworm Eisenia fetida under experimental conditions of tropical and temperate regions.

Plant Protection Products can affect soil organisms and thus might have negative impacts on soil functions. Little research has been performed on their impact on tropical soils. Therefore, the effects of the insecticide lambda-Cyhalothrin on earthworms were evaluated in acute and chronic laboratory tests modified for tropical conditions, i.e. at selected temperatures (20 and 28 °C) and with two strains (temperate and tropical) of the compost worm Eisenia fetida. The insecticide was spiked in two natural soils, in OECD artificial soil and a newly developed tropical artificial soil. The effects of lambda-Cyhalothrin did rarely vary in the same soil at tropical (LC50: 68.5?229 mg a.i./kg dry weight (DW); EC50: 54.2?60.2 mg a.i./kg DW) and temperate (LC50: 99.8?140 mg a.i./kg DW; EC50: 37.4?44.5 mg a.i./kg DW) temperatures. In tests with tropical soils and high temperature, effect values differed by up to a factor of ten

Soil ants.

Between July 1997 and March 1999 ants of soil and litter were taken every three months with core samplers (21cm ø) in a primary rain forest, a secondary forest and two different systems of polycultures in central Amazonia (Brazil) and extracted in Berlese funnels. Greatest generic diversity wasfound in pirmary forest, while in secondary forest and the two polycultures it was about 20% and 30% lower, respectively. Biomass and median density of ants were also highest in primary forest followed by secondary forest and one of the polyculture, whereas the lowest number and biomass of ants was found in the second polyculture. The predatory species of Hypoponera reresented the biggest part of ant biomass in all areas (20%-30%), whereas the very abundant mostly tiny species (<2mm) of Solenopsis made up only 1,4%-3,9% of the ant biomass.Final Report 1996-1999

Anomalous Higgs Couplings

We review the effects of new effective interactions on the Higgs boson phenomenology. New physics in the electroweak bosonic sector is expected to induce additional interactions between the Higgs doublet field and the electroweak gauge bosons leading to anomalous Higgs couplings as well as to anomalous gauge-boson self-interactions. Using a linearly realized $SU(2)_L \times U(1)_Y$ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, we review the effects of the new effective interactions on the Higgs boson production rates and decay modes. We summarize the results from searches for the new Higgs signatures induced by the anomalous interactions in order to constrain the scale of new physics in particular at CERN LEP and Fermilab Te vatron colliders.Comment: 35 pages, latex using epsfig.sty psfig.sty and axodraw.sty, 16 postscript figure

Anderson transitions : multifractal or non-multifractal statistics of the transmission as a function of the scattering geometry

The scaling theory of Anderson localization is based on a global conductance $g_L$ that remains a random variable of order O(1) at criticality. One realization of such a conductance is the Landauer transmission for many transverse channels. On the other hand, the statistics of the one-channel Landauer transmission between two local probes is described by a multifractal spectrum that can be related to the singularity spectrum of individual eigenstates. To better understand the relations between these two types of results, we consider various scattering geometries that interpolate between these two cases and analyse the statistics of the corresponding transmissions. We present detailed numerical results for the power-law random banded matrices (PRBM model). Our conclusions are : (i) in the presence of one isolated incoming wire and many outgoing wires, the transmission has the same multifractal statistics as the local density of states of the site where the incoming wire arrives; (ii) in the presence of backward scattering channels with respect to the case (i), the statistics of the transmission is not multifractal anymore, but becomes monofractal. Finally, we also describe how these scattering geometries influence the statistics of the transmission off criticality.Comment: 12 pages, 9 figure