940 resultados para linear solvation energy relationships


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A reduction in LDL cholesterol and an increase in HDL cholesterol levels are clinically relevant parameters for the treatment of dyslipidaemia, and exercise is often recommended as an intervention. This study aimed to examine the effects of acute, high-intensity exercise (similar to 90% VO(2max)) and varying carbohydrate levels (control, low and high) on the blood lipid profile. Six male subjects were distributed randomly into exercise groups, based on the carbohydrate diets (control, low and high) to which the subjects were restricted before each exercise session. The lipid profile (triglycerides, VLDL, HDL cholesterol, LDL cholesterol and total cholesterol) was determined at rest, and immediately and 1 h after exercise bouts. There were no changes in the time exhaustion (8.00 +/- A 1.83; 7.82 +/- A 2.66; and 9.09 +/- A 3.51 min) and energy expenditure (496.0 +/- A 224.8; 411.5 +/- A 223.1; and 592.1 +/- A 369.9 kJ) parameters with the three varying carbohydrate intake (control, low and high). Glucose and insulin levels did not show time-dependent changes under the different conditions (P > 0.05). Total cholesterol and LDL cholesterol were reduced after the exhaustion and 1 h recovery periods when compared with rest periods only in the control carbohydrate intake group (P < 0.05), although this relation failed when the diet was manipulated. These results indicate that acute, high-intensity exercise with low energy expenditure induces changes in the cholesterol profile, and that influences of carbohydrate level corresponding to these modifications fail when carbohydrate (low and high) intake is manipulated.

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The paper discusses the availability of biomass in Brazil to supply charcoal to the steel industry on the bases of an initial global assessment of land potentially available for plantations and of Brazilian data that allows refining the assessment and specifying the issue of practical availability. Technical potentials are first assessed through a series of simple rules against direct competition with agriculture, forests and protected areas, and of quantitative criteria, whether geo-climatic (rainfall), demographic (population density) or legal (reserves). Institutional, social and economic factors are then identified and discussed so as to account for the practical availability of Brazilian biomass through six criteria. The ranking of nine Brazilian States according to these criteria brings out the necessary trade-offs in the selection of land for plantations that would efficiently supply charcoal to the steel industry. (C) 2008 Elsevier Ltd. All rights reserved.

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We analyzed the usefulness of a semi-tethered field running test (STR) and the relationships between indices of anaerobic power, anaerobic capacity and running performance in 9 trained male sprinters (22.2 +/- 2.9 yrs, 176 +/- 1 cm, 68.0 +/- 9.4 kg). STR involved an all out 120 m run attached to an apparatus that enabled power calculation from force and velocity measures. Subjects also carried out a cycloergometer Win-gate Anaerobic Test (WT), an all out 300 m run and had accessed their maximal accumulated oxygen deficit (MAOD) on a treadmill. Peak and mean powers attained in STR (1 720 +/- 221 and 1 391 +/- 201 W) were greater but significantly related (r=0.82; P<0.01) to those in the WT (808 +/- 130 and 603 +/- 87 W). In addition, power measures derived from the STR were stronger related to running performance compared to those from the WT (r=0.81-0.94 vs. 0.68-0.84; P<0.05). Relationships between MAOD and most power indices were only weak to moderate. These results support the usefulness of STR for specific power assessment in field running and suggest that anaerobic power and capacity are not related entities, irrespective of having been evaluated using similar or dissimilar exercise modes.

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MgB(2) is considered to be an important conductor for applications. Optimizing flux pinning in these conductors can improve their critical currents. Doping can influence flux pinning efficiency and grain connectivity, and also affect the resistivity, upper critical field and critical temperature. This study was designed to attempt the doping of MgB(2) on the Mg sites with metal-diborides using high-energy ball milling. MgB(2) samples were prepared by milling pre-reacted MgB(2) and TaB(2) powders using a Spex 8000M mill with WC jars and balls in a nitrogen-filled glove box. The mixing concentration in (Mg(1-x)Ta(x))B(2) was up to x = 0.10. Samples were removed from the WC jars after milling times up to 4000 minutes and formed into pellets using cold isostatic pressing. The pellets were heat treated in a hot isostatic press (HIP) at 1000 degrees C under a pressure of 30 kpsi for 24 hours. The influence that milling time and TaB(2) addition had on the microstructure and the resulting superconducting properties of TaB(2)-added MgB(2) is discussed. Improvement J(c) of at high magnetic fields and of pinning could be obtained in milled samples with added TaB(2) The sample with added 5at.% TaB(2) and milled for 300 minutes showed values of J(c) similar to 7 x 10(5) A/cm(2) and F(p) similar to 14 GN/m(3) at 2T, 4.2 K. The milled and TaB(2)-mixed samples showed higher values of mu(0)H(irr) than the unmilled-unmixed sample.

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Refractory castables are composed of fractions of fine to fairly coarse particles. The fine fraction is constituted primarily of raw materials and calcium aluminate cement, which becomes hydrated, forming chemical bonds that stiffen the concrete during the curing process. The present study focused on an evaluation of several characteristics of two refractory castables with similar chemical compositions but containing aggregates of different sizes. The features evaluated were the maximum load, the fracture energy, and the ""relative crack-propagation work"" of the two castables heat-treated at 110, 650, 1100 and 1550 degrees C. The results enabled us to draw the following conclusions: the heat treatment temperature exerts a significant influence on the matrix/aggregate interaction, different microstructures form in the castables with temperature, and a relationship was noted between the maximum load and the fracture energy. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

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In this work, the synthesis of Y(2)O(3) stabilized tetragonal zirconia polycrystals (Y-TZP)-alumina (Al(2)O(3)) powder mixture was performed by high-energy ball milling and the sintering behavior of this composite was investigated. In order to understand the phase transformations occurring during ball milling, samples were collected after different milling times, from 1 to 60 h. The milled powders were compacted by cold uniaxial pressing and sintered at 1400 and 1600 degrees C. Both powders and sintered samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry analysis (EDS) and mechanical properties. Fully dense samples were obtained after sintering at 1600 degrees C, while the samples sintered at 1400 degrees C presented a full density for powder mixtures milled for 30 and 60 h. Fracture toughness and Vickers hardnessvalues of the Y-T-ZP/Al(2)O(3) nanocomposite were improved due to dispersed Al(2)O(3) grains and reduced ZrO(2) grain size. Samples sintered at 1400 degrees C, based on powders milled for 60 h, presented high K(IC) and hardness values near to 8.0 Mpan(1/2) and 15 GPa, respectively (C) 2008 Elsevier B.V. All rights reserved

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Purpose: The diagnosis of cancer and the treatment decisions associated with it may cause uncertainty, stress, and anxiety among parents. Emotional tensions can affect parents` relationships during the trajectory of the child`s cancer illness. We conducted an integrative review to examine the evidence related to the effects of childhood cancer on parents` relationships. Methods: An integrative literature search of studies published between 1997 and 2009 was conducted in the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Psychology Information (PsycINFO), PubMed, Scopus, CUIDEN, and Latin American and Caribbean Health Science Literature (LILACS). The key words used were neoplasms, child, marriage, spouses, family relations, and nursing. Articles were reviewed if the (a) topic addressed parents` relationships during childhood cancer; (b) participants were mothers, fathers, or both; (c) design was either qualitative or quantitative; (d) language was English, Portuguese, or Spanish; (e) date of publication was between January 1997 and October 2009; and (f) abstract was available. Results: Fourteen articles met the search criteria and were reviewed using Cooper`s framework for integrative reviews. Four themes emerged: (a) changes in the parents` relationship during the trajectory of the child`s illness; (b) difficulty in communication between couples; (c) gender differences in parental stress and coping; and (d) role changes. Conclusions and Implications: Findings revealed positive and negative changes in parents` relationships, communication, stress, and roles. Nurses need to assess the impact of cancer diagnosis and treatments on parent relationships, offer support and encouragement, and allow expression of feelings. Future research is needed to develop and test interventions that increase parents` potentials and strengthen relationships during the challenging trajectory of their children`s cancer and treatment. Clinical Relevance: The multiple sources of stress and uncertainty associated with a child`s cancer diagnosis and treatment affect parents` relationships. Difficulties in communication appear frequently in parents` relationship. Our findings may guide healthcare professionals in identifying parents at risk for developing conflicts, communication problems, and lack of alignment between parents that could interfere with providing optimal care for their child with cancer. Healthcare professionals may promote dialogue and encourage parents to express their feelings, seek mutual support, and establish a partnership in dealing with the child`s illness.

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A new simple method to design linear-phase finite impulse response (FIR) digital filters, based on the steepest-descent optimization method, is presented in this paper. Starting from the specifications of the desired frequency response and a maximum approximation error a nearly optimum digital filter is obtained. Tests have shown that this method is alternative to other traditional ones such as Frequency Sampling and Parks-McClellan, mainly when other than brick wall frequency response is required as a desired frequency response. (C) 2011 Elsevier Inc. All rights reserved.

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This paper presents a robust voltage control scheme for fixed-speed wind generators using a static synchronous compensator (STATCOM) controller. To enable a linear and robust control framework with structured uncertainty, the overall system is represented by a linear part plus a nonlinear part that covers an operating range of interest required to ensure stability during severe low voltages. The proposed methodology is flexible and readily applicable to larger wind farms of different configurations. The performance of the control strategy is demonstrated on a two area test system. Large disturbance simulations demonstrate that the proposed controller enhances voltage stability as well as transient stability of induction generators during low voltage ride through (LVRT) transients and thus enhances the LVRT capability. (C) 2011 Elsevier Ltd. All rights reserved.

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This work proposes a method based on both preprocessing and data mining with the objective of identify harmonic current sources in residential consumers. In addition, this methodology can also be applied to identify linear and nonlinear loads. It should be emphasized that the entire database was obtained through laboratory essays, i.e., real data were acquired from residential loads. Thus, the residential system created in laboratory was fed by a configurable power source and in its output were placed the loads and the power quality analyzers (all measurements were stored in a microcomputer). So, the data were submitted to pre-processing, which was based on attribute selection techniques in order to minimize the complexity in identifying the loads. A newer database was generated maintaining only the attributes selected, thus, Artificial Neural Networks were trained to realized the identification of loads. In order to validate the methodology proposed, the loads were fed both under ideal conditions (without harmonics), but also by harmonic voltages within limits pre-established. These limits are in accordance with IEEE Std. 519-1992 and PRODIST (procedures to delivery energy employed by Brazilian`s utilities). The results obtained seek to validate the methodology proposed and furnish a method that can serve as alternative to conventional methods.

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This work deals with the main contributions of human resource dimensions for the environmental management in a company. While the specialized literature concerning the technical aspects of environmental management expands, there is a gap in the bibliography: integrated approaches between human resource dimensions and environmental management. An extensive bibliographical review was undertaken in order to systematize the human resource dimensions and their contributions concerning the effectiveness of the environmental management system. A model that analyses the relationships between these dimensions and the typical phases of an environmental management system is presented, within a perspective of application for academicians and managers. (c) 2006 Elsevier Ltd. All rights reserved.

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This work presents a non-linear boundary element formulation applied to analysis of contact problems. The boundary element method (BEM) is known as a robust and accurate numerical technique to handle this type of problem, because the contact among the solids occurs along their boundaries. The proposed non-linear formulation is based on the use of singular or hyper-singular integral equations by BEM, for multi-region contact. When the contact occurs between crack surfaces, the formulation adopted is the dual version of BEM, in which singular and hyper-singular integral equations are defined along the opposite sides of the contact boundaries. The structural non-linear behaviour on the contact is considered using Coulomb`s friction law. The non-linear formulation is based on the tangent operator in which one uses the derivate of the set of algebraic equations to construct the corrections for the non-linear process. This implicit formulation has shown accurate as the classical approach, however, it is faster to compute the solution. Examples of simple and multi-region contact problems are shown to illustrate the applicability of the proposed scheme. (C) 2011 Elsevier Ltd. All rights reserved.

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This paper proposes a physical non-linear formulation to deal with steel fiber reinforced concrete by the finite element method. The proposed formulation allows the consideration of short or long fibers placed arbitrarily inside a continuum domain (matrix). The most important feature of the formulation is that no additional degree of freedom is introduced in the pre-existent finite element numerical system to consider any distribution or quantity of fiber inclusions. In other words, the size of the system of equations used to solve a non-reinforced medium is the same as the one used to solve the reinforced counterpart. Another important characteristic of the formulation is the reduced work required by the user to introduce reinforcements, avoiding ""rebar"" elements, node by node geometrical definitions or even complex mesh generation. Bounded connection between long fibers and continuum is considered, for short fibers a simplified approach is proposed to consider splitting. Non-associative plasticity is adopted for the continuum and one dimensional plasticity is adopted to model fibers. Examples are presented in order to show the capabilities of the formulation.

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This work deals with analysis of cracked structures using BEM. Two formulations to analyse the crack growth process in quasi-brittle materials are discussed. They are based on the dual formulation of BEM where two different integral equations are employed along the opposite sides of the crack surface. The first presented formulation uses the concept of constant operator, in which the corrections of the nonlinear process are made only by applying appropriate tractions along the crack surfaces. The second presented BEM formulation to analyse crack growth problems is an implicit technique based on the use of a consistent tangent operator. This formulation is accurate, stable and always requires much less iterations to reach the equilibrium within a given load increment in comparison with the classical approach. Comparison examples of classical problem of crack growth are shown to illustrate the performance of the two formulations. (C) 2009 Elsevier Ltd. All rights reserved.

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This study presents a solid-like finite element formulation to solve geometric non-linear three-dimensional inhomogeneous frames. To achieve the desired representation, unconstrained vectors are used instead of the classic rigid director triad; as a consequence, the resulting formulation does not use finite rotation schemes. High order curved elements with any cross section are developed using a full three-dimensional constitutive elastic relation. Warping and variable thickness strain modes are introduced to avoid locking. The warping mode is solved numerically in FEM pre-processing computational code, which is coupled to the main program. The extra calculations are relatively small when the number of finite elements. with the same cross section, increases. The warping mode is based on a 2D free torsion (Saint-Venant) problem that considers inhomogeneous material. A scheme that automatically generates shape functions and its derivatives allow the use of any degree of approximation for the developed frame element. General examples are solved to check the objectivity, path independence, locking free behavior, generality and accuracy of the proposed formulation. (C) 2009 Elsevier B.V. All rights reserved.