GLOBAL DYNAMICS of THE LORENZ SYSTEM WITH INVARIANT ALGEBRAIC SURFACES

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modeling a system of phosphated cross-linked high amylose for controlled drug release. Part 2: Physical parameters, cross-linking degrees and drug delivery relationships

High amylose cross-linked to different degrees with sodium trimetaphosphate by varying base strength (2% or 4%) and contact time (0.5-4 h) was evaluated as non-compacted systems for sodium diclophenac controlled release. The physical properties and the performance of these products for sodium diclophenac controlled release from non-compacted systems were related to the structures generated at each cross-linking degree. For samples at 2% until 2 h the swelling ability, G' and eta* values increased with the cross-linking degree, because the longer polymer chains became progressively more entangled and linked. This increases water uptake and holding, favoring the swelling and resulting in systems with higher viscosities. Additionally, the increase of cross-linking degree should contribute for a more elastic structure. The shorter chains with more inter-linkages formed at higher cross-linking degrees (2%4h and 4%) make water caption and holding difficult, decreasing the swelling, viscosity and elasticity. For 2% samples, the longer drug release time exhibited for 2%4h sample indicates that the increase of swelling and viscosity contribute for a more sustained drug release, but the mesh size of the polymeric network seems to be determinant for the attachment of drug molecules. For the 4% samples, smaller meshes size should determine less sustained release of drug. (C) 2008 Elsevier B.V. All rights reserved.

AC Biosusceptometry as a Tool for Monitoring the Gastrointestinal Transit of Multiparticulate Drug Delivery System

Drug delivery systems based on natural polysaccharides, such as chitosan (CS) and pectin (PC), rather than on synthetic polymers, have been widely studied. Some reasons for that are low toxicity and costs and high biodegradability of the formers. A multiparticulate system based on CS and PC was developed in our laboratories, including the addition of an enteric polymer, cellulose acetate phtalate (CAP). Such improvement promoted stronger gastric and enteric resistances, as assessed in vitro, making the systems more selective to enzymatic degradation in the colon. Although in vitro dissolution tests can simulate some properties concerning the gastrointestinal transit (GT), collaborating to characterize the systems behavior in the biological fluids, frequently they do not result in satisfactory in vitro/in vivo correlations. The objective of this work was to follow in vivo the GT of the particles developed by means of AC biosusceptometry (ACB), a non-invasive and of low cost methodology. The particles containing ferrite in powder form were prepared by complex coacervation using an ideal 3:1:1 mass ratio for PC:CS:CAP. The magnetic particles were administered to healthy volunteers by oral route. The GT was monitored by using multi-sensor ACB system and the signal acquisition was performed every IS min until the colonic region was reached. By means of ACB technique, it was possible to acquiring images generated by the magnetic particles within the whole gastrointestinal tract including the colonic region. Variable particles transit times were observed among the volunteers, but without interference on the mapping of the particles until the colonic region. The particles were able to produce magnetic field strong enough to generate signals adequate for mapping the particles. The results suggest that integral particles reached the colon, after they resisted against gastric and enteric media. Studies associating transit time and in vivo drug release are in development in order to confirm the efficiency of the systems.

An Intelligent System for Petroleum Well Drilling Cutting Analysis

Cutting analysis is a important and crucial task task to detect and prevent problems during the petroleum well drilling process. Several studies have been developed for drilling inspection, but none of them takes care about analysing the generated cutting at the vibrating shale shakers. Here we proposed a system to analyse the cutting's concentration at the vibrating shale shakers, which can indicate problems during the petroleum well drilling process, such that the collapse of the well borehole walls. Cutting's images are acquired and sent to the data analysis module, which has as the main goal to extract features and to classify frames according to one of three previously classes of cutting's volume. A collection of supervised classifiers were applied in order to allow comparisons about their accuracy and efficiency. We used the Optimum-Path Forest (OPF), Artificial Neural Network using Multi layer Perceptrons (ANN-MLP), Support Vector Machines (SVM) and a Bayesian Classifier (BC) for this task. The first one outperformed all the remaining classifiers. Recall that we are also the first to introduce the OPF classifier in this field of knowledge. Very good results show the robustness of the proposed system, which can be also integrated with other commonly system (Mud-Logging) in order to improve the last one's efficiency.

Environmental management system and human resource practices: is there a link between them in four Brazilian companies?

The aim of this article is to analyze the theoretical model proposed by [Jabbour CJC, Santos FCA. Relationships between human resource dimensions and environmental management in companies: proposal of a model. Journal of Cleaner Production 2008;16(1):5 1-8.] based on the data collected in four Brazilian companies. This model investigates how the phases of the environmental management system can be linked to human resource practices in order to attain continuous improvement of a company's environmental performance. Our aim is to contribute to a field, which has little empirical evidence. Although the interaction between the phases of the environmental management system and human resource practices is recommended by the specialized literature [Daily BE Huang S. Achieving sustainability through attention to human resource factors in environmental management. International Journal of Operations and Production Management 2001:21(12):1539-52.], the results indicate that most of the theoretical assumptions could not be confirmed in these Brazilian companies. (C) 2008 Elsevier Ltd. All rights reserved.

An efficient Hopfield network to solve economic dispatch problems with transmission system representation

Economic dispatch (ED) problems have recently been solved by artificial neural network approaches. Systems based on artificial neural networks have high computational rates due to the use of a massive number of simple processing elements and the high degree of connectivity between these elements. The ability of neural networks to realize some complex non-linear function makes them attractive for system optimization. All ED models solved by neural approaches described in the literature fail to represent the transmission system. Therefore, such procedures may calculate dispatch policies, which do not take into account important active power constraints. Another drawback pointed out in the literature is that some of the neural approaches fail to converge efficiently toward feasible equilibrium points. A modified Hopfield approach designed to solve ED problems with transmission system representation is presented in this paper. The transmission system is represented through linear load flow equations and constraints on active power flows. The internal parameters of such modified Hopfield networks are computed using the valid-subspace technique. These parameters guarantee the network convergence to feasible equilibrium points, which represent the solution for the ED problem. Simulation results and a sensitivity analysis involving IEEE 14-bus test system are presented to illustrate efficiency of the proposed approach. (C) 2004 Elsevier Ltd. All rights reserved.

Beam Search Algorithms for Minimizing Tool Switches on a Flexible Manufacturing System

In the minimization of tool switches problem we seek a sequence to process a set of jobs so that the number of tool switches required is minimized. In this work different variations of a heuristic based on partial ordered job sequences are implemented and evaluated. All variations adopt a depth first strategy of the enumeration tree. The computational test results indicate that good results can be obtained by a variation which keeps the best three branches at each node of the enumeration tree, and randomly choose, among all active nodes, the next node to branch when backtracking.

Pole placement method using the system matrix transfer function and sparsity

This paper presents a pole placement method using both the augmented Jacobian and the corresponding system transfer function matrices. From the manipulation of these matrices a straightforward approach results to get the coefficients of a non-linear system, whose solution gives the parameters of the stabilizers that can provide a pre-specified minimum damping to the system. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Pole placement by coordinated tuning of Power System Stabilizers and FACTS-POD stabilizers

This work presents the application of the Decentralized Modal Control method for pole placement in multimachine power systems utilizing FACTS (Flexible AC Transmission Systems), STATCOM (Static Synchronous Compensator) and UPFC (Unified Power Flow Controller) devices. For this, these devices are equipped with supplementary damping controllers, denominated POD ( Power Oscillation Damping), achieving a coordinated project with local controllers (Power System Stabilizers - PSS). Comparative analysis on the function of damping of the FACTS, STATCOM and UPFC is performed using the New England System that has 10 generators, 39 buses and 46 transmission lines. (c) 2011 Elsevier Ltd. All rights reserved.

Real-time multi-sensors measurement system with temperature effects compensation for impedance-based structural health monitoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analysis of the performance of an extraction-condensation steam turbine on a cogeneration system of a Brazilian sugar-alcohol factory

In this work a detailed thermodynamic analysis for an extraction-condensation steam turbine capable to drive a 40 MVA electricity generator in a sugar-alcohol factory was carried out. The use of this turbine in the cogeneration system showed that its efficiency contributed to increase the power generation, although the condensation reduces the overall efficiency of the plant. Sensibility analyses were performed to evaluate the behavior of the overall energy efficiency of a plant with the extraction-condensation turbine in function of the boiler efficiency, the specific consumption of steam in the processes and the condensation rate in the turbine. It was observed that the plant efficiency is very sensible to the condensation rate variation and it increases when there is an increase in the demand of steam for processes.

The Impact of Domestic Politics and International Changes on the Brazilian Perception of Regional Integration

This article aims to analyze the impact of domestic politics and international changes that influence Brazilian positions regarding regional integration processes in South America, particularly the Southern Common Market, Mercosur. The dynamics of the international system and their impact on the evolution of the elite's perception of the role the country should play in the world are important variables for understanding these positions. The state's postures in relation to integration were and are based on a real interest, but this interest is also linked with the objective of ensuring better conditions for participation in other international arenas. Starting with the hypothesis that transformations in the international setting have strongly influenced Brazil's positioning, the elements of continuity and change in the country's behavior toward Mercosur are identified, with domestic politics as the main explanation.

High incidences of DNA ploidy abnormalities in tongue squamous cell carcinoma of young patients: an international collaborative study

Aims: This multi-centre analysis assessed the DNA content of TSCC in 37 young patients (<40 years) and 28 old patients (>50 years) and determined the correlation of DNA ploidy findings with clinicopathological data.Methods and results: Image cytometry was carried out using an automated cellular imaging system on Feulgen-stained histological sections to obtain high-fidelity DNA histograms. Among young patients, 37.8% were females compared to 18.7% in the older group (P = 0.002). In total, 48.6% patients were non-smokers and 40.5% were non-drinkers compared to 10.7% non-smokers and non-drinkers in the older group (P < 0.0001). TNM, clinical stage of disease and histological grade of differentiation did not differ between groups. Tumour aneuploidy was detected in 86.5% and tetraploidy in 24.3% young patients; this was significantly greater than in the older group where 64.3% were aneuploid (P < 0.0001) and 7.2% tetraploid (P < 0.0001). The mean values of DNA index (DI) and DNA heterogeneity index as well as the percentage of cells with DI exceeding 5N were higher in young patients (P < 0.0001).Conclusions: Young patients with TSCC represent a distinct clinical entity. The high incidence of DNA ploidy abnormalities suggest that they may have increased genomic instability and indicates underlying genetic differences between TSCC in young and older patients.

Antibacterial effectiveness of several irrigating solutions and the Endox Plus system - an ex vivo study

Aim To compare the ex vivo antibacterial effectiveness of the Endox Plus system and sodium hypochlorite (NaOCl) in combination with BioPure MTAD (Tulsa Dental, Tulsa, OK, USA) or with EDTA in Enterococcus faecalis-contaminated root canals.Methodology After initial preparation, the root canals of 70 single-rooted human teeth were inoculated with E. faecalis (ATCC 29212) and incubated for 21 days. Specimens were divided into five groups: Endox Plus/saline; 2.5% NaOCl/MTAD; 2.5% NaOCl/EDTA; saline (positive control); negative control (root canals not prepared, nor irrigated). Samples were collected using paper points. Microbiological analysis evaluated the number of CFUs. Data were analysed by anova and Tukey tests at 0.05 significance.Results All specimens had bacterial growth after the incubation period, with similar CFU per mL counts (P > 0.05). After chemo-mechanical preparation, the number of bacteria in all groups reduced, except for the negative control. No significant differences were observed between 2.5% NaOCl/MTAD and 2.5% NaOCl/EDTA, but these groups had lower CFU counts than the other groups (P < 0.05). In the final samples, an increase in the bacterial counts was observed for Endox Plus/saline, 2.5% NaOCl/MTAD, 2.5% NaOCl/EDTA and saline (P < 0.05) with no significant differences between these groups.Conclusions This ex vivo study revealed that the Endox Plus system was associated with a reduced antibacterial effectiveness compared with conventional irrigation using 2.5% NaOCl/MTAD and 2.5% NaOCl/EDTA. All irrigation procedures allowed recovery of bacteria 7 days after treatment, demonstrating persistence of contamination within the root canal system.

Evaluation of the thermoplasticity of gutta-percha and Resilon (R) using the Obtura II System at different temperature settings

Aim To analyse the thermoplasticity of several endodontic filling materials using the Obtura II System at different temperature settings.Methodology The following materials based on gutta-percha: Regular Obtura (OBT), Obtura Flow 150 (OBT F), Endo Flow (EDF), Odous (ODO) and the synthetic thermoplastic polymer material Resilon (RE) were heated using the Obtura II System at three temperature settings (140, 170 and 200 degrees C). Samples of the heated materials were placed on the sensor of a digital thermometer (THR-140; Instrutherm, São Paulo, Brazil) to determine their real temperature (RT) when the system was set at 140 degrees C (from 64.5 to 69 degrees C), 170 degrees C (from 73.8 to 77.5 degrees C) and 200 degrees C (from 83.6 degrees C for EDF and 100 degrees C for RE). Specimens (n = 30) were made by placing samples of each material in metallic ring moulds and compressing them between two glass slabs. After 24 h, specimens (n = 10) were heated at the different settings (RT) and submitted to compression under a 5-kg load. Plasticization was assessed by calculating the differences between the post-compression and initial diameters of each specimen. Data were submitted to ANOVA and Tukey's test at 5% significance.Results At 140 degrees C, Obtura Flow presented the highest thermoplasticity values and Regular Obtura, the lowest. At 170 degrees C, Obtura Flow and Resilon demonstrated greater plasticization. Resilon had the highest mean thermoplasticity values at 200 degrees C.Conclusions Thermoplasticity values were influenced both by the temperature settings on the Obtura II System and by the type of material analysed. Obtura Flow and Resilon had the highest mean thermoplasticity values.