Signal-flow graphs: Direct method of reduction and MATLAB implementation

Block diagrams and signal-flow graphs are used to represent and to obtain the transfer function of interconnected systems. The reduction of signal-flow graphs is considered simpler than the reduction of block diagrams for systems with complex interrelationships. Signal-flow graphs reduction can be made without graphic manipulations of diagrams, and it is attractive for a computational implementation. In this paper the authors propose a computational method for direct reduction of signal-flow graphs. This method uses results presented in this paper about the calculation of literal determinants without symbolic mathematics tools. The Cramer's rule is applied for the solution of a set of linear equations, A program in MATLAB language for reduction of signal-flow graphs with the proposed method is presented.

Dentistry in Brazil: Its History and Current Trends

The objectives of this article are to provide a short history of dentistry and dental education in Brazil and to analyze the nature of its development to date. The databases consulted are those provided by the Brazilian Federal Council of Dentistry, Brazilian Ministry of Health, Brazilian Ministry of Education, National Institute of Studies and Educational Research Anisio Teixeira, and Brazilian Institute of Geography and Statistics. Formal dental education in Brazil started in the late nineteenth century with the creation of courses annexed to existing schools of medicine in Rio de Janeiro and Bahia. Today, there are 191 institutions of higher education nationwide granting degrees in dentistry (137 private [71.7 percent] and fifty-four public [28.3 percent]), with a total of 17,157 student positions offered annually. These schools graduate around 10,000 professionals per year-one of the highest rates in the world. Both the distribution of schools of dentistry and of dentists varies among the regions of the country, with the greatest concentrations in major metropolitan centers with high population density, resulting in limited coverage in the more deprived regions. A review of epidemiological data for oral health and distribution of dentists in Brazil indicates that there is a lack of systematic planning for the allocation of the dental workforce and a lack of consideration of regional needs in the development of dental training programs in Brazil today.

Use of FIA systems for on-line dilution in multielement determination by ICP-MS

A flow-injection (FI) system to match concentrations was used as an auto-diluter in multielement determination by inductively coupled plasma-mass spectrometry (ICP-MS). The flow system comprised loop-based injection or a timed valve that introduced a variable sample volume info a spray chamber through a standard Meinhard nebulizer of an ICP-MS. Routinely analyzed samples such as water, plant, and steel were selected. The accuracy of multielement determination was checked against water standard reference material from the National Institute of Standards and Technology (1643d), plant standard reference material from the National Bureau of Standards (1572 citrus leaves), and steel standard reference material from the National Bureau of Standards (AISI 4340). The measuring system was calibrated with a multielement solution, yielding a linear plot with good precision [relative standard deviation (RSD) < 3%, n = 12]. The results were in agreement at a 95% confidence level with the certified values for the reference materials and also with those obtained by continuous aspiration and by (FI) with a discrete volume. (C) 1999 John Wiley & Sons, Inc.

Electrical and Magnetic Characterization of BSCCO and YBCO HTS Tapes for Fault Current Limiter Application

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photon-induced multiple particle emissions of Zr90 and natZr from 10 to 140 MeV

A comprehensive analysis of electrodisintegration yields of protons on Zr90 is proposed taking into account the giant dipole resonance, isovector giant quadrupole resonance (IVGQR), and quasideuteron contributions to the total photoabsorption cross section from 10 to 140 MeV. The calculation applies the MCMC intranuclear cascade to address the direct and pre-equilibrium emissions and another Monte Carlo-based algorithm to describe the evaporation step. The final results of the total photoabsorption cross section for Zr90 and relevant decay channels are obtained by fitting the (e,p) measurements from the National Bureau of Standards and show that multiple proton emissions dominate the photonuclear reactions at higher energies. These results provide a consistent explanation for the exotic and steady increase of the (e,p) yield and also a strong evidence of a IVGQR with a strength parameter compatible with the E2 energy-weighted sum rule. The inclusive photoneutron cross sections for Zr90 and natZr, derived from these results and normalized with the (e,p) data, are in agreement within 10% with both Livermore and Saclay data up to 140 MeV. © 2007 The American Physical Society.

Report on the coordination of international statistical activities in the area of the environment

Includes bibliography.

Findings of the survey on international classifications in Latin America

Spanish document available at the Library

A política de regularização fundiária e reforma agrária: o PAE nas ilhas do Pará

O objetivo desse trabalho é realizar um estudo sobre a Política de Regularização Fundiária e Reforma Agrária na Região Amazônica, a partir do II Plano Nacional de Reforma Agrária (II PNRA), que inseriu as populações tradicionais ribeirinhas no conjunto de seu público. Tendo como foco de análise os projetos de assentamentos em ilhas dos municípios da Microrregião do Baixo Tocantins/PA, realizados por uma força tarefa entre o INCRA e a SPU. Contudo, a proposta de democratização do uso e posse da terra, que possibilita a seguridade fundiária às populações ribeirinhas, não foi priorizada e estrategicamente planejada pelas instituições públicas. Mediante as análises do processo decisório e dos planos de ação das instituições, das percepções e coleta de dados do associativismo das populações assentadas e dos resultados das eleições do período de 2000 a 2010, chegou-se à conclusão de que os projetos de assentamentos foram realizados de forma intensa e desordenada, para responder positivamente a índices de reforma agrária do governo Lula e para causar impacto nos resultados eleitorais essenciais à manutenção da governabilidade do sistema político.

Multielemental evaluation of garbage bags by EDXRF

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Analysis of the influence of baffles and shields on the cooling of a digital transmission equipment

In this work design criteria for cooling of electronic systems used in a digital transmission equipment are considered. An experimental study using a simulated electronic equipment in which vertically oriented circuit boards are aligned to form vertical channels is carried out. Resistors are used to simulate actual components. The temperature of several components in the printed circuit boards are measured and the influence of the baffles and shields on the cooling effect are discussed. It was observed that the use of the baffles reduce the temperature levels and, the use of shields, although protecting the components from magnetic effects, cause an increase in the temperature levels.

Analysis of linearity and frequency response of a novel piezoelectric flextensional actuator using a homodyne interferometer and the J(1)-J(4) method

Piezoelectric transducers are widely used in high-resolution positioning systems. This paper reports the experimental analysis of a novel piezoelectric flextensional actuator (PFA), which is designed by using the topology-optimization method through a low-cost homodyne Michelson interferometer. By applying the J(1) - J(4) method for signal demodulation, which provides a linear and direct measurement of dynamic optical phase shift independent of fading, the nanometric displacements of the PFA were determined. Linearity and frequency response of the PFA were evaluated up to 50 kHz. PFA calibration factor and amplification rate were determined for the PFA operating in the quasi-static regime. To confirm the observed frequencies of resonance, an impedance analyzer is also utilized to measure the magnitude and phase of the PFA admittance.

Representation of transmission lines: comparison of models and parameters distributed discrete parameters

A transmission line is characterized by the fact that its parameters are distributed along its length. This fact makes the voltages and currents along the line to behave like waves and these are described by differential equations. In general, the differential equations mentioned are difficult to solve in the time domain, due to the convolution integral, but in the frequency domain these equations become simpler and their solutions are known. The transmission line can be represented by a cascade of π circuits. This model has the advantage of being developed directly in the time domain, but there is a need to apply numerical integration methods. In this work a comparison of the model that considers the fact that the parameters are distributed (Universal Line Model) and the fact that the parameters considered concentrated along the line (π circuit model) using the trapezoidal integration method, and Simpson's rule Runge-Kutta in a single-phase transmission line length of 100 km subjected to an operation power. © 2003-2012 IEEE.

A legitimação das avaliações em larga escala no discurso sobre gestão educacional

Pós-graduação em Educação - FFC

The effects of 2 mg chlormadinone acetate/30 mcg ethinylestradiol, alone or combined with spironolactone, on cardiovascular risk markers in women with polycystic ovary syndrome

Background: Polycystic ovary syndrome (PCOS) is an endocrine disorder associated with metabolic dysfunction and changes in cardiovascular risk markers, and using oral contraceptives (OCs) may exert a further negative effect on these alterations in patients with PCOS. Thus, the primary objective of this study was to assess the effects on arterial function and structure of an OC containing chlormadinone acetate (2 mg) and ethinylestradiol (30 mcg), alone or combined with spironolactone (OC+SPL), in patients with PCOS. Study Design: This was a randomized, controlled clinical trial. Fifty women with PCOS between 18 and 35 years of age were randomized by a computer program to use OC or OC+SPL. Brachial artery flow-mediated vasodilation, carotid intima-media thickness and the carotid artery stiffness index were evaluated at baseline and after 6 and 12 months. Serum markers for cardiovascular disease were also analyzed. The intragroup data were analyzed using analysis of variance with Tukey's post hoc test. A multivariate linear regression model was used to analyze the intergroup data. Results: At 12 months, the increase in mean total cholesterol levels was greater in the OC+SPL group than in the OC group (27% vs. 13%, respectively; p=.02). The increase in mean sex hormone-binding globulin levels was greater in the OC group than in the OC+SPL group (424% vs. 364%, respectively; p=.01). No statistically significant differences between the groups were found for any of the other variables. Conclusion: The addition of spironolactone to an OC containing chlormadinone acetate and ethinylestradiol conferred no cardiovascular risk-marker advantages in young women with PCOS. (C) 2012 Elsevier Inc. All rights reserved.

Correlation Between Molecular Conformation, Packing, and Dynamics in Oligofluorenes: A Theoretical/Experimental Study

Fluorene-based systems have shown great potential as components in organic electronics and optoelectronics (organic photovoltaics, OPVs, organic light emitting diodes, OLEDs, and organic transistors, OTFTs). These systems have drawn attention primarily because they exhibit strong blue emission associated with relatively good thermal stability. It is well-known that the electronic properties of polymers are directly related to the molecular conformations and chain packing of polymers. Here, we used three oligofluorenes (trimer, pentamer, and heptamer) as model systems to theoretically investigate the conformational properties of fluorene molecules, starting with the identification of preferred conformations. The hybrid exchange correlation functional, OPBE, and ZINDO/S-CI showed that each oligomer exhibits a tendency to adopt a specific chain arrangement, which could be distinguished by comparing their UV/vis electronic absorption and C-13 NMR spectra. This feature was used to identify the preferred conformation of the oligomer chains in chloroform-cast films by comparing experimental and theoretical UV/vis and C-13 NMR spectra. Moreover, the oligomer chain packing and dynamics in the films were studied by DSC and several solid state NMR techniques, which indicated that the phase behavior of the films may be influenced by the tendency that each oligomeric chain has to adopt a given conformation.