Elementos finitos em formulação mista de mínimos quadrados para a simulação da convecção-difusão em regime transiente

Um esquema de elementos finitos mistos de tipo mínimos quadrados é estudado para resolver as equações da convecção-difusão transientes expressas em função tanto do campo incógnito primário como do seu fluxo, incorporando ou não um termo reativo. Uma vez efetuada uma discretização temporal à la Crank-Nicholson, o sistema de equações resultante permite uma aproximação estável desses 2 campos, com elementos finitos contínuos de Lagrange clássicos de grau arbitrário em geometria de tipo simplex ou não, em dimensão espacial qualquer. O esquema é convergente em espaço no sentido da média quadrática no que tange ao campo incógnito primário, a seu gradiente, à variável de fluxo e à divergência desta última, e no tempo num sentido apropriado para cada um desses campos. Os resultados numéricos atestam o bom desempenho do esquema, para quaisquer números de Péclet, confirmando as previsões teóricas, pelo menos no caso de camadas limite estreitas em que o método se mostra fracassado. A técnica é também comparada com outros métodos para resolver essas equações, incluindo 2 propostos recentemente pelo primeiro autor et al.A mixed least-squares finite element scheme designed for solving the transient convection-diffusion equations expressed in terms of both the primal unknown and its flux, incorporating or not a reaction term, is studied. Once a time discretization of the Crank-Nicholson type is performed, the resulting system of equations allows for a stable approximation of both fields, by means of classical Lagrange continuous piecewise polynomial functions of arbitrary degree, in both simplicial and non-simplicial geometry, in any space dimension. The scheme is also convergent in space in the mean-square sense as far as the primal unknown field, its gradient, the flux variable and its divergence are concerned, and in time in an appropriate sense for each one of these four fields. Numerical results certify that the scheme performs well for any Péclet number, thereby allowing to confirm theoretical predictions, at least in the case where there is no narrow boundary layer. In the latter case however the method fails to produce reliable results. The technique is also compared with three existing methods to solve the convection-diffusion equations in the transient case. These include two recent ones proposed by the first author and collaborators.Peer Reviewe

Crop ontology in support of conservation and use of banana genetic resources

Poster presented at Workshop on Crop Ontology and Phenotyping Data Interoperability. Montpellier (France), 31 Mar-4 Apr 201

Lower-extremity side-to-side strength asymmetry of professional soccer players according to playing position

Previous studies have utilized screening values of 10-15% of lower-extremity side-to-side strength asymmetry in soccer players with conflicting results. The purpose of this study was to determine differences in screening values for side-to-side asymmetry in soccer players according to their playing position, as well as to compare the differences in strength asymmetry between particular playing positions. Seventy-nine Brazilian male professional soccer players (age 26.1±5.3 years; body mass 79.8±14.4 kg; body height 180.4±12.9 cm) were grouped into playing positions of: goalkeepers, side backs, central backs, central defending midfielders, central attacking midfielders, and forwards. They performed maximal knee extension and flexion concentric and knee flexion eccentric actions on their preferred and non-preferred legs at 1.047 rad·s-1. Forwards and goalkeepers had hamstrings concentric peak torque asymmetry (18.0±9.9%) and eccentric peak torque asymmetry (20.1±10.7%) significantly greater than 10% (p<.05). All other playing positions had values less than 15%. Our results indicate that the use of either 10 or 15% asymmetry cut off may result in different conclusions, which may affect decision-making regarding strength ratios. Furthermore, if 10% is used as a screening value, hamstrings strengthening programs based on bilateral equivalency should be prescribed for goalkeepers and forwards to reduce asymmetry

The early exercise boundary under the jump to default extended CEV model

This paper proves the existence, uniqueness, monotonicity and continuity of the early exercise boundary attached to American-style standard options under the jump to default extended constant elasticity of variance model of Carr and Linetsky (Financ Stoch 10(3):303–330, 2006).info:eu-repo/semantics/acceptedVersio

Acute effects of proprioceptive neuromuscular facilitation on peak torque and muscle imbalance

Background: The effects of proprioceptive neuromuscular facilitation (PNF) stretching on muscle imbalance are not fully understood. The aim of this study was to examine the acute effects of PNF stretching on knee extension and flexion peak torque (PT), as well as the conventional and functional hamstrings to quadriceps (H:Q) ratios. Methods: Fifteen men (age = 22 ± 1 years; body mass = 76 ± 12 kg; height = 176 ± 7 cm) and fifteen women (age = 22 ± 2 years; body mass = 63 ± 8 kg; height = 161 ± 5 cm) performed concentric quadriceps and hamstrings, and eccentric hamstrings muscle actions at different angular velocities (60, 180, and 300 ◦ ·s −1 concentric; 60 and 180 ◦ ·s −1 eccentric) before and after a bout of PNF stretching, and a control condition. Results: Neither PNF or control conditions affected concentric PT or H:Q ratios (p \u3e 0.05), apart from knee extension at 60 ◦ ·s −1 in men (p = 0.001). However, there was a reduction in hamstrings eccentric PT in both control and PNF conditions for men and women (p = 0.003). Conclusions: PNF stretching of the hamstrings may not adversely affect the H:Q ratios, and consequently not negatively affect injury risk associated with muscular strength imbalances

Effects of different combinations of concentric and eccentric resistance training programs on traditional and alternative hamstrings-to-quadriceps ratios

Resistance training is often recommended for combined increases in traditional and alternative hamstrings-to-quadriceps (H:Q) ratios in order to reduce knee strength imbalance and associated hamstrings and knee ligament injury risk. The aim of this study was to investigate the effect of different concentric and eccentric resistance training programs on traditional and alternative H:Q ratios. Forty male volunteers were assigned to one of 4 groups: concentric quadriceps and concentric hamstrings (CON/CON, n = 10), eccentric quadriceps and eccentric hamstrings (ECC/ECC, n = 10), concentric quadriceps and eccentric hamstrings (CON/ECC, n = 10), or no training (control (CNTRL), n = 10). Traditional conventional (CR) and functional (FR), alternative rate of torque development (RTD), muscle size (MS), and muscle activation (MA) H:Q ratios were measured before and after six weeks of unilateral nondominant knee extension–flexion resistance training performed on an isokinetic dynamometer. The ECC/ECC training significantly increased FR (pre = 0.75 ± 0.11; post = 0.85 ± 0.15), whereas the lack of training (CNTRL) decreased the RTD H:Q ratio (pre = 1.10 ± 0.67; post = 0.73 ± 0.33). There were no differences between groups for the other traditional and alternative ratios following resistance training protocols. These findings suggest eccentric exercise for quadriceps and hamstrings as the most beneficial training program for inducing increases in the traditional FR. However, different resistance training strategies may be needed to also elicit increases in the alternative RTD, MS, and MA H:Q ratios for fully restoring muscle balance and reducing potential hamstrings and knee ligament injury risk

Alternative methods of determining hamstrings-to-quadriceps ratios: A comprehensive review

The hamstrings-to-quadriceps muscle strength ratio calculated by peak torque has been used as an important tool to detect muscle imbalance, monitor knee joint stability, describe muscle strength properties and functionality, and for lower extremity injury prevention and rehabilitation. However, this ratio does not consider other neuromuscular variables that can also influence the antagonist to agonist muscle relationship, such as torque produced at multiple angles of range of motion, explosive strength, muscle size, muscle fatigue, or muscle activation. The aim of this study was to comprehensively review alternative methods of determining the hamstrings-to-quadriceps ratio. These include ratios calculated by angle-specific torque, rate of torque development, muscle size, fatigue index, and muscle activation (measured by electromyography). Collectively, the literature demonstrates that utilizing alternative methods of determining the hamstrings-to-quadriceps ratio can be functionally relevant for a better understanding of the neuromuscular mechanisms underpinning the interaction of strength between hamstrings and quadriceps. However, there is insufficient evidence to recommend any of the alternative methods as sensitive clinical tools for predicting injury risk and monitoring knee joint integrity. Future longitudinal studies, along with injury incidence, are needed to further investigate all alternative methods of determining the hamstrings-to-quadriceps ratio. These have potential to offer insight into how athletes and the general population should be trained for performance enhancement and injury reduction, and may be used along with traditional methods for a thorough assessment of an individual\u27s H:Q muscle balance

Genetic diversity among forty coffee varieties assessed by RAPD markers associated with restriction digestion

The genetic variability of 40 accessions of_C. arabica was evaluated using a combination of the random amplified polymorphic DNA (RAPD) technique and restriction digestion of genomic DNA. The genetic variability and the relatedness among all accessions were initially evaluated using 195 RAPD primers which revealed a very low level of genetic variation. To improve the efficiency in the detection of polymorphism, the genomic DNA of all accessions were submitted to digestion with restriction endonucleases prior to PCR amplification. A total of 24 primers combined with restriction digestion of DNA rendered 318 bands, of which 266 (83.65%) were polymorphic. The associations among genotypes were estimated using UPGMA-clustering analysis. The accessions were properly clustered according to pedigree and agronomic features. The ability to distinguish among coffee accessions was greater for RAPD plus restriction digestion than for RAPD alone, providing evidences that the combination of the techniques was very efficient for the estimation of genetic relationship among_C. arabica genotypes.Leandro Eugênio Cardamoni Diniz, Claudete de Fátima Ruas, Valdemar de Paula Carvalho, Fabrício Medeiros Torres, Eduardo Augusto Ruas, Melissa de Oliveira Santos, Tumoru Sera and Paulo Maurício Rua

Dinâmica folicular e momento da ovulação em vacas não lactantes das raças Gir e Nelore durante duas estações do ano.

vacas não lactantes da raça Gir (10 no inverno e 15 no verão) e 15 vacas não lactantes da raça Nelore (sete no inverno e oito no verão), todas com ciclo estral normal. Após a detecção do estro, as vacas foram submetidas a exames ultra-sonográficos a cada seis horas com a finalidade de monitorar o momento de ovulação e, posteriormente, uma vez ao dia durante todo o ciclo estral, sendo monitorado um ciclo estral por animal e por estação do ano. As características foliculares não foram afetadas pela estação do ano e não diferiram entre as raças. Houve maior percentagem de ciclos com três (68,0 e 66,7%) e duas ondas foliculares (24,0 e 26,7%) nas raças Gir e Nelore, respectivamente. Os intervalos entre estros e entre ovulações foram menores para ciclos com duas ondas foliculares. A manifestação do estro ocorreu mais nas primeiras horas da manhã (57,3%) e no final da tarde e início da noite (28,0%). O momento de ovulação ocorreu 23,1±5,6 horas após a detecção do estro nas duas raças