Finite time blow-up and breaking of solitary wind waves

The evolution of surface water waves in finite depth under wind forcing is reduced to an antidissipative Korteweg-de Vries-Burgers equation. We exhibit its solitary wave solution. Antidissipation accelerates and increases the amplitude of the solitary wave and leads to blow-up and breaking. Blow-up occurs in finite time for infinitely large asymptotic space so it is a nonlinear, dispersive, and antidissipative equivalent of the linear instability which occurs for infinite time. Due to antidissipation two given arbitrary and adjacent planes of constant phases of the solitary wave acquire different velocities and accelerations inducing breaking. Soliton breaking occurs in finite space in a time prior to the blow-up. We show that the theoretical growth in amplitude and the time of breaking are both testable in an existing experimental facility.

The structure of non-abelian kinks

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

Three-dimensional analysis of reinforced concrete members via embedded discontinuity finite elements

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

Uso de invertase imobilizada em pó de sabugo de milho para produção de açúcar invertido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise de corrosão, dureza e fratura de conjuntos implantes / componentes protético de Titânio c.p., após serem submetidos a ciclos de fadiga em um meio fluoretado com diferentes PH

Atualmente o titânio é empregado como biomaterial devido à sua biocompatibilidade e resistência à corrosão. Entretanto, íons fluoretos, freqüentemente empregados em dentifrícios bucais, podem interferir no processo de corrosão. O objetivo deste estudo foi analisar a influência de um meio fluoretado com diferentes pH nas propriedades mecânicas e na resistência à corrosão dos conjuntos implantes/componentes protéticos à base de Ti c.p., a partir dos testes de fadiga, microscopia eletrônica de varredura (MEV) e dureza. Foram simulados cinco anos de uso regular de meios de higiene oral com conteúdo de 1500 ppm de NaF, com dois diferentes pH, 7,4 e 5,3, mediante imersão das amostras nesses meios durante 184 horas e também em água destilada, grupo controle. As amostras foram testadas num durômetro Micromet 2001 (500gf/30s). Os dados dos testes de dureza foram analisados pelo teste de Wilcoxon, demonstrando que as amostras sofreram influência negativa na dureza após a ação dos íons fluoreto. Entretanto, essa influência não ocorreu nos testes de fadiga realizados em uma máquina de ensaios mecânicos MTS-810, fixada a 100.000 ciclos, 15Hz e programada com força de fadiga a 150 N. Pela análise de MEV foram constatadas evidências de corrosão na superfície das amostras após ação de íons fluoretos, entretanto pelo EDS não se verificou incorporação de íons fluoretos sobre a superfície dos conjuntos. Concluiu-se que a concentração de flúor e o pH das soluções não exerceram influência nas propriedades mecânicas.

Antidepressants for anorexia nervosa

Background Anorexia Nervosa ( AN) is an illness characterised by extreme concern about body weight and shape, severe self-imposed weight loss, and endocrine dysfunction. In spite of its high mortality, morbidity and chronicity, there are few intervention studies on the subject.Objectives The aim of this review was to evaluate the efficacy and acceptability of antidepressant drugs in the treatment of acute AN.Search strategy The strategy comprised of database searches of the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register, MEDLINE (1966 to April 28th, 2005), EMBASE (1980 to week 36, 2004), PsycINFO (1969 to August week 5, 2004), handsearching the International Journal of Eating Disorders and searching the reference lists of all papers selected. Personal letters were sent to researchers in the field requesting information on unpublished or in-progress trials.Selection criteria All randomised controlled trials of antidepressant treatment for AN patients, as de fined by the Diagnostic and Statistical Manual, fourth edition (DSM-IV) or similar international criteria, were selected.Data collection and analysis Quality ratings were made giving consideration to the strong relationship between allocation concealment and potential for bias in the results; studies meeting criteria A and B were included. Trials were excluded if non-completion rates were above 50%. The standardised mean difference and relative risk were used for continuous data and dichotomous data comparisons, respectively. Whenever possible, analyses were performed according to intention- to-treat principles. Heterogeneity was tested with the I-squared statistic. Weight change was the primary outcome. Secondary outcomes were severity of eating disorder, depression and anxiety symptoms, and global clinical state. Acceptability of treatment was evaluated by considering non-completion rates.Main results Only seven studies were included. Major methodological limitations such as small trial size and large confidence intervals decreased the power of the studies to detect differences between treatments, and meta-analysis of data was not possible for the majority of outcomes. Four placebo-controlled trials did not find evidence that antidepressants improved weight gain, eating disorder or associated psychopathology. Isolated findings, favouring amineptine and nortriptyline, emerged from the antidepressant versus antidepressant comparisons, but cannot be conceived as evidence of efficacy of a specific drug or class of antidepressant in light of the findings from the placebo comparisons. Non-completion rates were similar between the compared groups.Authors' conclusions A lack of quality information precludes us from drawing de finite conclusions or recommendations on the use of antidepressants in acute AN. Future studies testing safer and more tolerable antidepressants in larger, well designed trials are needed to provide guidance for clinical practice.

The fracture resistance of a CAD/CAM Resin Nano Ceramic (RNC) and a CAD ceramic at different thicknesses

Objective. This study aimed to investigate the influence of restoration thickness to the fracture resistance of adhesively bonded Lava (TM) Ultimate CAD/CAM, a Resin Nano Ceramic(RNC), and IPS e. max CAD ceramic.Methods. Polished Lava (TM) Ultimate CAD/CAM (Group L), sandblasted Lava (TM) Ultimate CAD/CAM (Group LS), and sandblasted IPS e.max CAD (Group ES) discs (n=8, phi=10 mm) with a thickness of respectively 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, and 3.0 mm were cemented to corresponding epoxy supporting discs, achieving a final thickness of 3.5 mm. All the 120 specimens were loaded with a universal testing machine at a crosshead speed of 1 mm/min. The load (N) at failure was recorded as fracture resistance. The stress distribution for 0.5 mm restorative discs of each group was analyzed by Finite Element Analysis (FEA). The results of facture resistances were analyzed by one-way ANOVA and regression.Results. For the same thickness of testing discs, the fracture resistance of Group L was always significantly lower than the other two groups. The 0.5 mm discs in Group L resulted in the lowest value of 1028 (112) N. There was no significant difference between Group LS and Group ES when the restoration thickness ranged between 1.0 mm and 2.0 mm. There was a linear relation between fracture resistance and restoration thickness in Group L (R = 0.621, P < 0.001) and in Group ES (R = 0.854, P < 0.001). FEA showed a compressive permanent damage in all groups.Significance. The materials tested in this in vitro study with the thickness above 0.5 mm could afford the normal bite force. When Lava Ultimate CAD/CAM is used, sandblasting is suggested to get a better bonding. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A method for calculating the compliance of bonded-interfaces under shrinkage: Validation for Class I cavities

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

Finite element evaluation of three methods of stable fixation of condyle base fractures

The surgical treatment of mandibular condyle fractures currently offers several possibilities for stable internal fixation. In this study, a finite element model evaluation was performed of three different methods for osteosynthesis of low subcondylar fractures: (1) two four-hole straight plates, (2) one seven-hole lambda plate, and (3) one four-hole trapezoidal plate. The finite element model evaluation considered a load applied to the first molar on the contralateral side to the fracture. Results showed that, although the three methods are capable of withstanding functional loading, the lambda plate displayed a more homogeneous stress distribution for both osteosynthesis material and bone and may be a better method when single-plate fixation is the option.

Higher-derivative non-Abelian gauge fields via the Faddeev-Jackiw formalism

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

EFFECT OF FOOD SHORTAGE ON GROWTH, ENERGETIC RESERVES MOBILIZATION, AND WATER QUALITY IN JUVENILES OF THE REDCLAW CRAYFISH, CHERAX QUADRICARINATUS, REARED IN GROUPS

The aim of this study is to analyze the impact of food shortage on growth performance, by means of energetic reserves (proteins, glycogen and lipids) mobilization and hepatopancreas cells analysis in C. quadricarinatus juveniles maintained in groups, as well as the effect on culture water quality. Two experiments were performed, each of them with two feeding regimes during 45 days. The Control feeding regime, in which crayfish were fed daily (once a day) throughout the experimental period (DF), and the Cyclic feeding regime, in which juveniles were fed for 2 or 4 days (once a day) followed by 2 or 4 days of food deprivation (2F/2D and 4F/4D, respectively) in repeated cycles. Cyclic feeding influenced growth, biochemical composition from hepatopancreas and muscle, and water quality. Juveniles cyclically fed were unable to maintain a normal growth trajectory during 45 days. Apparent feed conversion ratio, apparent protein efficiency ratio, hepatosomatic index and relative pleon mass were similar in cyclic and daily fed animals and no structural damage was found in the hepatopancreas of juveniles subjected to cyclic feeding. The novelty of this study was the significant accumulation of proteins in pleonal muscle in both cyclic feeding regimes (approx. 18%) suggesting that the storage of this constitutive material during food shortage may be an adaptation for a compensatory growth when food becomes abundant again. The cyclic feeding regimes had a positive effect on water quality decreasing inorganic nitrogen concentration. This was due to the reduction in the amount of animal excretes and feces in the group that received approx. 50% less feed. Additionally, water pH was higher in cyclic feeding tanks, as a result of lower organic matter decomposition and consequent release of CO2. Accordingly, total ammonia in the water was significantly lower for the cyclic feeding regimes compared to their respective controls. This study suggests that the protocol of cyclic feeding could be applied at least 45 days in 1 g juveniles maintained in group conditions, without affecting the energetic reserves and hepatopancreas structure, emphasizing the high tolerance of this species to food restriction.

Modeling of multiple cracks in reinforced concrete members using solid finite elements with high aspect ratio

This paper presents a new technique to model interfaces by means of degenerated solid finite elements, i.e., elements with a very high aspect ratio, with the smallest dimension corresponding to the thickness of the interfaces. It is shown that, as the aspect ratio increases, the element strains also increase, approaching the kinematics of the strong discontinuity. A tensile damage constitutive relation between strains and stresses is proposed to describe the nonlinear behavior of the interfaces associated with crack opening. To represent crack propagation, couples of triangular interface elements are introduced in between all regular (bulk) elements of the original mesh. With this technique the analyses can be performed integrally in the context of the continuum mechanics and complex crack patterns involving multiple cracks can be simulated without the need of tracking algorithms. Numerical tests are performed to show the applicability of the proposed technique, studding also aspects related to mesh objectivity.

Vertical distribution by demographic groups of ghost crab Ocypode quadrata (Crustacea: Brachyura)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

FINITE ELEMENT SIMULATIONS FOR THE COMPREHENSION OF PHYSICAL PHENOMENA INVOLVED IN ELECTRIC IMPEDANCE TOMOGRAPHY OF MASONRY STRUCTURES

The paper describes the preliminary studies of University of Minho on the use of Electric Impedance/Resistance Tomography to assess masonry structures. The study is focused on the analysis of values of current and voltage resulting from the use of an electrical source with voltage and frequency values from a distribution network. The analysis is made from results obtained through computer simulations, using a three-dimensional model of the idealized masonry structures. A finite element program was used for the simulations. Three types of electrodes were used in simulations, and the analysis of the results led to significant conclusions. Later masonry specimens were built and a series of preliminary tests were carried out in the laboratory. The comparative analysis of simulated and experimental results allowed identifying the factors that have influence on the physical results.