Demographic Change and the Structure of Wages: A Demand-Theoretic Analysis for Brazil

With rapidly declining fertility and increased longevity the age structure of the labor force in developing countries has changed rapidly. Changing relative supply of workers by age group, and by educational attainment, can have profound effects on labor costs. Their impacts on earnings have been heavily studied in the United States but have received little attention in Asia and Latin America, where supply shocks are at least as large and have often proceeded less evenly across the economy. We use data on 502 local Brazilian labor markets from Censuses 1970-2000 to examine the extent of substitution among demographic groups as relative supply has changed. The results suggest that age-education groups are imperfect substitutes, so that larger age-education cohorts see depressed wage rates, particularly among more-educated groups. The extent of substitution has increased over time, so that the decreasing size of the least-skilled labor force today is barely raising its remaining members' wages.

Use of manganese oxides recovered from spent batteries in electrocatalysis of oxygen reduction reaction in alkaline medium

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)UFAB

Baixos níveis de glicemia e outras complicações durante suplementação de hormônio do crescimento na sepse

O perfil glicêmico esperado em pacientes pós-operatórios sépticos recebendo nutrição enteral de elevado teor calórico é de valores sanguíneos no limite superior do normal ou mesmo hiperglicemia moderada.A adição de hormônio do crescimento (GH) como agente anabólico deveria reforçar ainda mais esta tendência.Num paciente com câncer submetido a gastrectomia parcial e linfadenectomia, que se complicou no pós operatório com abscesso subfrênico e sepse prolongada, administrou-se conjuntamente dieta de sonda (38,3 kcal/kg/dia) e GH (0,17 UI/kg/dia).Antes da introdução de GH as taxas glicêmicas situavam-se nos limites inferiores do normal, e esta tendência persistiu durante a maior parte do período terapêutico.Duas complicações adicionais, nominalmente parada cardíaca e edema periférico, foram documentadas nesta mesma etapa.Conclui-se que a sepse é o mais provável mecanismo de redução da glicemia neste caso, e que o emprego de dieta enteral e de GH não conseguiu prevenir tal efeito.É questionável se a parada cardíaca foi devida ao suplemento hormonal, mas o edema periférico é um secundarismo bem conhecido deste agente em estudos clínicos.Blood glucose levels in the high normal range or even moderate hyperglycemia is the expected profile in septic postoperative patients receiving high-calorie enteral alimentation. The addition of growth hormone as an anabolic agent should additionally reinforce this tendency. In a cancer patient undergoing partial gastrectomy with lymphadenectomy and suffering from postoperative subphrenic abscess and prolonged sepsis, tube feeding (38.3 kcal/kg/day) and growth hormone (0.17 IU/kg/day) were simultaneously administered for 25 days. Blood glucose levels were in the lower limits of the normal range before growth hormone introduction, and continued with a similar tendency during most of the therapeutic period. Two additional complications, namely heart arrest and peripheral edema, were documented during the same period. It is concluded that sepsis was the most likely mechanism for low glucose values, and that high-calorie enteral diet and growth hormone supplementation did not prevent that result. It is uncertain whether heart arrest was due to the drug, but its association with peripheral edema is well documented in clinical series

On the Electromagnetic Response of Charged Bosons Coupled to a Chern-Simons Gauge Field: A Path Integral Approach

We analyze the electromagnetic response of a system of charged bosons coupled to a Chern-Simons gauge field. Path integral techniques are used to obtain an effective action for the particle density of the system dressed with quantum fluctuations of the CS gauge field. From the action thus obtained we compute the U(1) current of the theory for an arbitrary electromagnetic external field. For the particular case of a homogeneous external magnetic field, we show that the quantization of the transverse conductivity is exact, even in the presence of an arbitrary impurity distribution. The relevance of edge states in this context is analyzed. The propagator of density fluctuations is computed, and an effective action for the matter density in the presence of a vortex excitation is suggested.Comment: LaTex file, 27 pages, no figure

How close can one approach the Dirac point in graphene experimentally?

The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10^6 cm^2V^-1s^-1 and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as \approx10^8 cm^-2, allowing a neutral state with a few charge carriers per entire micron-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap

Berry's phase and Quantum Dynamics of Ferromagnetic Solitons

We study spin parity effects and the quantum propagation of solitons (Bloch walls) in quasi-one dimensional ferromagnets. Within a coherent state path integral approach we derive a quantum field theory for nonuniform spin configurations. The effective action for the soliton position is shown to contain a gauge potential due to the Berry phase and a damping term caused by the interaction between soliton and spin waves. For temperatures below the anisotropy gap this dissipation reduces to a pure soliton mass renormalization. The gauge potential strongly affects the quantum dynamics of the soliton in a periodic lattice or pinning potential. For half-integer spin, destructive interference between soliton states of opposite chirality suppresses nearest neighbor hopping. Thus the Brillouin zone is halved, and for small mixing of the chiralities the dispersion reveals a surprising dynamical correlation: Two subsequent band minima belong to different chirality states of the soliton. For integer spin, the Berry phase is inoperative and a simple tight-binding dispersion is obtained. Finally it is shown that external fields can be used to interpolate continuously between the Bloch wall dispersions for half-integer and integer spin.Comment: 20 pages, RevTex 3.0 (twocolumn), to appear in Phys. Rev. B 53, 3237 (1996), 4 PS figures available upon reques

Cartilha ilustrada como instrumento de educação ambiental

Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.A urgência em preservar os recursos naturais cresce cada vez mais. Há a necessidade de se pensar globalmente e buscar agir localmente para que assim consigamos reduzir os impactos ambientais que nos atingem diretamente. Com esse pensamento em mente, surgiu a oportunidade de utilizar uma alternativa para atrair o interesse e incentivar a ação da população através de uma forma simples e atrativa, buscando a conscientização e educação ambiental como ferramentas para a redução de impactos antrópicos apenas com simples práticas domésticas. Colocando em foco a educação infantil, trabalhando o reaproveitamento e reciclagem de materiais, visando a preservação de matéria prima e informações sobre preservação e recuperação de áreas degradadas e matas ciliares, através do formato de história em quadrinhos e usando linguagem acessível. A cartilha ambiental foi elaborada em forma de revista em quadrinhos, buscando introduzir informalmente a cartilha à população da região São Bento do Tocantins. A distribuição do material ocorreu em palestras, escolas e encerramento da operação na cidade, através de abordagens. Os 2.000 exemplares foram produzidos e distribuídos, esperando alcançar um público aproximado de 5.000 pessoas. A cidade de São Bento do Tocantins não possui saneamento básico adequado, utilizam de lixão, boa parte da população relatou que não fazem separação dos resíduos, não utilizam de coleta seletiva e possuem fossa negra para disposição do esgoto doméstico. O Rio São Bento, que banha a cidade, encontra-se com sua margem degradada pela erosão e desmate da vegetação. Através da viagem precursora foi possível identificar tais situações para trabalhar com a população. Com depoimentos coletados, as cartilhas já foram trabalhadas em salas de aula da cidade. Tendo em mente que educação ambiental é um tema que deve ser abordado sempre e que seus resultados na maioria das vezes podem ser percebidos apenas a longo prazo, a resposta que obtivemos da população foi positiva, uma vez que recebemos depoimentos dos professores que utilizaram a cartilha em sala de aula indicando que o material foi muito bem recebido pelos alunos e de fácil abordagem

Stability of gene contributions and identification of outliers in multivariate analysis of microarray data

BACKGROUND: Multivariate ordination methods are powerful tools for the exploration of complex data structures present in microarray data. These methods have several advantages compared to common gene-by-gene approaches. However, due to their exploratory nature, multivariate ordination methods do not allow direct statistical testing of the stability of genes. RESULTS: In this study, we developed a computationally efficient algorithm for: i) the assessment of the significance of gene contributions and ii) the identification of sample outliers in multivariate analysis of microarray data. The approach is based on the use of resampling methods including bootstrapping and jackknifing. A statistical package of R functions was developed. This package includes tools for both inferring the statistical significance of gene contributions and identifying outliers among samples. CONCLUSION: The methodology was successfully applied to three published data sets with varying levels of signal intensities. Its relevance was compared with alternative methods. Overall, it proved to be particularly effective for the evaluation of the stability of microarray data

Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table