Locally periodic unfolding method and two-scale convergence on surfaces of locally periodic microstructures

In this paper we generalize the periodic unfolding method and the notion of two-scale convergence on surfaces of periodic microstructures to locally periodic situations. The methods that we introduce allow us to consider a wide range of non-periodic microstructures, especially to derive macroscopic equations for problems posed in domains with perforations distributed non-periodically. Using the methods of locally periodic two-scale convergence (l-t-s) on oscillating surfaces and the locally periodic (l-p) boundary unfolding operator, we are able to analyze differential equations defined on boundaries of non-periodic microstructures and consider non-homogeneous Neumann conditions on the boundaries of perforations, distributed non-periodically

Investigations of fast neutron production by 190 GeV/c muon interactions on different targets

The production of fast neutrons (1 MeV - 1 GeV) in high energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon, copper and lead targets. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross section.Comment: 19 pages, 11 figures ep

Familial Sneddon's syndrome

A syndrome associating Livedo Reticularis (LR) with Cerebrovascular disease (CVD) was described, in 1965, by Sneddon. It occurs sporadically, but a few familial cases of Sneddon's Syndrome (SS) have been reported, like these 3 cases that represent one of the largest number among siblings. We studied three male brothers, aged 28, 37 and 42 years, with CVD (ischaemic stroke in 2 patients and cerebral haemorrhages in the third) and their sister with no CVD. All patients presented with long lasting Livedo Reticularis, extending beyond the lower limbs. Skin biopsy on the centre of the reticular pattern showed, only in the second patient, partial endothelium detachment in dermo-hypodermic blood vessels. The males also had accesses of Livedoid Vasculitis (LV), in which a skin biopsy showed obliteration of several upper dermal vessels with hialin thrombi and a very scarce inflammatory infiltrate. Complementary studies, with an extensive investigation on pro-coagulation/pro-thrombotic features including antiphospholipid antibodies, were repeatedly negative. Their non-consanguineous parents were not affected, but among these kindred of 9 individuals, apart from the 4 patients reported above, LR and LV were present in two other brothers and also in an aunt and uncle, suggesting autosomal dominant pattern of inheritance, with incomplete penetrance. The relationship between Sneddon's Syndrome and Antiphospholipid Antibody Syndrome is controversial. The present cases, having repeatedly negative antiphospholipid antibodies, support the classification of Sneddon's Syndrome as an independent nosological entity

Plantas daninhas consumidas por bovinos em pastagem estabelecida em área de vegetação secundária no nordeste paraense.

Resumos do 24º Congresso Brasileiro da Ciência das Plantas Daninhas, 2004, São Pedro, PS

Initiation and evolution of phase separation in heteroepitaxial InAlAs films

We have investigated the initiation and evolution of phase separation in heteroepitaxial InAlAs films. In misfit-free InAlAs layers, cross-sectional scanning tunneling microscopy (XSTM) reveals the presence of isotropic nanometer-sized clusters. For lattice-mismatched InAlAs layers with 1.2% misfit, quasiperiodic contrast modulations perpendicular to the growth direction are apparent. Interestingly, these lateral modulations are apparently initiated within the first few bilayers of film growth, and both the amplitude and wavelength of the modulations increase with film thickness. The saturation value of the modulation wavelength determined from XSTM coincides with the lateral superlattice period determined from (002) x-ray reciprocal space maps, suggesting that the lateral modulation wavelength represents a periodic composition variation. Together, these results suggest that phase separation in the heteroepitaxial InAlAs thin-film system is a misfit-driven kinetic process initiated by random compositional nonuniformities, which later develop into coupled compositional and surface morphological variations. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69359/2/APPLAB-80-18-3292-1.pd

Spectroscopic determination of hole density in the ferromagnetic semiconductor Ga1−x_{1-x}Mnx_{x}As

The measurement of the hole density in the ferromagnetic semiconductor Ga$_{1-x}$Mn$_{x}$As is notoriously difficult using standard transport techniques due to the dominance of the anomalous Hall effect. Here, we report the first spectroscopic measurement of the hole density in four Ga$_{1-x}$Mn$_{x}$As samples ($x=0, 0.038, 0.061, 0.083$) at room temperature using Raman scattering intensity analysis of the coupled plasmon-LO-phonon mode and the unscreened LO phonon. The unscreened LO phonon frequency linearly decreases as the Mn concentration increases up to 8.3%. The hole density determined from the Raman scattering shows a monotonic increase with increasing $x$ for $x\leq0.083$, exhibiting a direct correlation to the observed $T_c$. The optical technique reported here provides an unambiguous means of determining the hole density in this important new class of ``spintronic'' semiconductor materials.Comment: two-column format 5 pages, 4 figures, to appear in Physical Review

Tomografia por impedância elétrica e seus possíveis usos na agropecuária.

bitstream/CNPDIA/10189/1/PA26_98.pd

Efeito de culturas antecessoras à cana-de-açúcar na composição florística de plantas daninhas.

O objetivo do presente trabalho foi de avaliar e identificar a composição florística de plantas daninhas em áreas de produção de cana-de-açúcar, nas diferentes estações do ano, no município de Felixlândia, MG, em resposta a diferentes cultivos antecessores ao plantio da canade- açúcar. O experimento foi conduzido na Fazenda Experimental da EPAMIG, no delineamento de blocos ao acaso, com seis tratamentos e quatro repetições, utilizando-se a variedade SP81-3250 de cana-de-açúcar. Os tratamentos foram os cultivos antecessores ao plantio da cana de: milheto (Pennisetum glaucum), crotalária (Crotalaria juncea), mucuna preta (Stizolobium aterrimum), guandu anão (Cajanus cajan) e soja (Glycine max), acrescido de uma testemunha (pastagem degradada de Brachiaria decumbens). Foram avaliadas a composição florística e as frequência, densidade e abundância relativa e o índice de valor de importância. Foram identificadas 23 espécies de plantas daninhas, distribuídas em 19 gêneros e 13 famílias. As famílias mais representativas foram as Leguminosae e Solanaceae, com quatro espécies, seguidas por Malvaceae, com três espécies, e Convolvulaceae e Rubiaceae com duas espécies. A espécie B. decumbens foi encontrada em todos os períodos do ano e em todos os diferentes sistemas de plantio da cana-de-açúcar nos períodos de inverno e primavera. As espécies Acanthospermum australe e Richardia brasiliensis apresentaram o maior IVI no período de outono. As diferenças encontradas na composição florística tanto em relação ao cultivo antecessor utilizado como às épocas avaliadas se tornam relevantes para o planejamento do manejo adequado das plantas daninhas na cultura da cana

Local and systemic metal ion release occurs intraoperatively during correction and instrumented spinal fusion for scoliosis

STUDY DESIGN: Prospective pilot study. OBJECTIVES: The aim of this study was to measure titanium, niobium and aluminium levels in various intraoperative and postoperative samples to determine patterns of metal ion release that occur within the first month following instrumented spinal fusion. Raised serum metal ion levels are reported following instrumented spinal fusion in adolescent idiopathic scoliosis. The exact topological origin and chronology of metal ion release remains conjectural. Recent literature suggests an immediate rise in serum metal levels within the first postoperative week. METHODS: Titanium, niobium and aluminium levels were measured before, during and after surgery in serum and local intraoperative fluid samples obtained from two pediatric patients undergoing posterior correction and instrumentation for scoliosis. RESULTS: Measurable metal ion levels were detected in all local samples obtained from wound irrigation fluid, cell saver blood, and fluid that immersed metal universal reduction screw tabs. Postoperative serum metal ion levels were elevated compared to baseline preoperative levels. In general, metal ion levels were considerably higher in the intraoperative fluid samples compared to those observed in the serum levels. CONCLUSION: Our findings of contextually high metal ion concentrations in intraoperative and early postoperative samples provide further empirical support of a 'putting-in' phenomenon of metal ion release following instrumented spinal fusion. This challenges existing beliefs that metal ion release occurs during an intermediate 'wearing-in' phase. We recommend thorough irrigation of the operative site prior to wound closure to dilute and remove intraoperative metal ion debris. Possibilities of filtering trace metal ions from cell saver content may be considered.William J. Cundy, Annika R. Mascarenhas, Georgia Antoniou, Brian J. C. Freeman, Peter J. Cund