Strength of non-traditional granular materials assessed from drained multistage triaxial tests

When granular materials are applied in geotechnical works, like embankments and road pavement layers, one of the most relevant engineering properties in stability analysis is ultimate shear strength. In geotechnical engineering, the triaxial test is one of the most reliable methods available for determining ultimate shear strength. In this test, a soil specimen, compacted in laboratory or collected from exploratory soil borings, is generally used. In order to determine the strength parameters, at least 3 identical specimens are required in this test. Having 3 identical specimens, a single stage triaxial test procedure is used. If not, multistage triaxial test procedure is used to eliminate the effects of soil variability in the results. In this case, several confining pressures are applied to the same specimen. Although multistage triaxial tests have been used for soils for a long time, there is still a lack of test results for unbound granular non-traditional materials. This paper presents triaxial test results obtained from a Portuguese unbound granular non-traditional material (named as Inert Steel Aggregate for Construction - ISAC). The triaxial tests were carried out using multistage and single stage techniques. As the results are quite well comparable, it is concluded that it is possible to determine shear strength parameters with just one specimen. Consequently, the research conducted has validated the use of multistage triaxial tests as a reliable and cost-effective alternative to the conventional single stage triaxial test in the mechanical characterization of unbound granular materials.The authors appreciate the financial support of the FCT for this project PCDT/ECM/56952/2004 through the POCI 2010 program and for the cohesion fund FEDER and a doctoral grant within company SFRH/BDE/15661/2007. Acknowledgments are also due to António Cavalheiro, deputy manager of the Seixal Iron Steel Company.info:eu-repo/semantics/publishedVersio

Kinematical changes in swimming front crawl and breaststroke with the AquaTrainer® snorkel

The aim of the present study was to assess the kinematical changes when swimming maximal bouts in Front Crawl and Breaststroke with the AquaTrainer® snorkel. Thirteen male swimmers (7 at Breaststroke and 6 at Front Crawl) of national level performed randomly two maximal bouts of 100-m swims: one bout using the Aqua- Trainer® snorkel (snorkel swim) and another one without the snorkel (free swim). The swims were videotaped in sagital plane with a pair of cameras providing 2D kinematics evaluation. The following measures were assessed: swimming performance (T100), stroke cycle period (P), stroke rate (SR), stroke length (SL), swimming velocity (v), swimming eYciency as estimated by the stroke index (SI), speed Xuctuation (dv) and the mathematical characterisation of dv. T100 was signiWcantly higher when swimming with the snorkel than in free swimming at Breaststroke (= 6.26%) and at Front Crawl (= 4.75%). P, SR and SL, as well as SI and dv did not present signiWcant diVerences. The main Wnding of the study was that changes in the swimming velocity imposed by the use of the Aquatrainer® do not seem due to changes in general kinematics or swimming eYcienc

Development of a novel cell encapsulation system based on natural origin polymers for tissue engineering applications

Cells microencapsulated in biocompatible semi-permeable polymeric membranes are effective as cell delivery systems while protecting the host against immune responses. In this study, cell encapsulation membranes were prepared based on carrageenan and alginate, two natural cationic polymers. Different formulations/conditions were explored to optimize the microcapsules which were characterized with respect to their morphology, mechanical stability, and cytotoxicity. Spherical-shaped microcapsules were obtained from all the polymeric systems. The iota-carrageenan/sodium alginate microcapsules exhibited the best stability and permeability, and therefore, these were selected for the cell encapsulation. These capsules provided an environment that supported cell proliferation and have the potential for tissue engineering as well as other cell-based therapy applications.One of the authors (SML) acknowledges the support of the Programme Alssan-the European Union Programme of High Level Scholarships for Latin America (scholarship no. E04M041362CO). This work was partially supported by the European STREP HIPPOCRATES (NMP3-CT-2003-505758) and by the Fundacao para a Ciencia e Tecnologia (project PTDC/QUI/68804/2006) and carried out under the scope of European NoE EXPERTISSUES (NMP3-CT-2004-500283)

Physiological assessment of head-out aquatic exercises in healthy subjects: a qualitative review

In the last decades head-out aquatic exercises became one of the most important physical activities within the health system. Massive research has been produced throughout these decades in order to better understand the role of head-out aquatic exercises in populations’ health. Such studies aimed to obtain comprehensive knowledge about the acute and chronic response of subjects performing head-out aquatic exercises. For that, it is assumed that chronic adaptations represent the accumulation of acute responses during each aquatic session. The purpose of this study was to describe the “state of the art” about physiological assessment of head-out aquatic exercises based on acute and chronic adaptations in healthy subjects based on a qualitative review. The main findings about acute response of head-out aquatic exercise according to water temperature, water depth, type of exercise, additional equipment used, body segments exercising and music cadence will be described. In what concerns chronic adaptations, the main results related to cardiovascular and metabolic adaptations, muscular strength, flexibility and body composition improvements will be reported

Comparação dos procedimentos metodológicos de reconstrução cinemática 2d na técnica de bruços – Duplo meio / planos seprados

O presente estudo teve como propósito principal o de averiguar os procedimentos bem como o grau de concordância das reconstruções dos parâmetros cinemáticos de execução na técnica de bruços com recurso a duas metodologias distintas de captura e reconstrução cinemétrica, duplo meio (DM) e planos separados (PS). A amostra foi constituída por 7 nadadores do sexo masculino especialistas na técnica de bruços (19.1 ± 4,3 anos de idade; 1.78 ± 0.62 m de estatura; 70.4 ± 8.0 kg de massa corporal; 69.10 ± 4.16 s de recorde pessoal aos 100 m Bruços em piscina longa). O protocolo consistiu na realização de um percurso de 100 m na técnica de bruços à máxima velocidade possível (prova maximal), em piscina de 50 metros. Os registos de imagem para posterior tratamento foram recolhidos por um sistema constituído por um par de câmaras de vídeo (uma subaquática - inclusa numa caixa estanque e uma de superfície). Assim, foram recolhidas as imagens da prova utilizando as duas metodologias, o DM e os PS. Duas câmaras registaram respectivamente imagens aéreas (GR-SX1 SVHS, JVC, Yokoama, Japão) e subaquáticas (GR-SXM25 SVHS, JVC, Yokoama, Japão) no plano sagital, a 25 metros da parede testa de partida. Foi efectuada a análise cinemática (Ariel Performance Analysis System, Ariel Dynamics Inc., Califórnia, EUA) de um ciclo gestual completo, através de um leitor de vídeo a 50 Hz (Panasonic, AG 7355, Japão). Recorreu-se ao método de digitalização em planos separados (aéreo e subaquático) e subsequente reconstrução pela aplicação do algoritmo2D-DLT [1]. Foi adoptado o modelo antropométrico de Zatsiorsky, adaptado por de Leva [6],, incluindo a divisão do tronco em 2 partes articuladas. Os sinais foram filtrados com uma frequência de corte de 5 Hz, como sugerido por Winter [15], com recurso a dupla-passagem. A fiabilidade do processo de digitalização-redigitalização para os dois métodos foi muito elevada (R = 0.97; ICR = .87; 0.95). Determinouse a duração absoluta do teste (T100, s), a duração absoluta do ciclo gestual (Durciclo), a frequência ciclo (FC, Hz), a distância de ciclo (DC, m), a velocidade de nado (v, m.s-1), o índice de nado (IN, m2.c-1.s-1), a flutuação intra-cíclica da velocidade horizontal do centro de massa (dv, %) e o deslocamento vertical do centro de massa corporal (Dy, m). Foi efectuada a comparação entre as duas situações com recurso a estatística não paramétrica (Teste de Wilcoxon) para P £ 0.05. O resultados sugerem-nos a ideia de que o padrão biomecânico de execução técnica dos nadadores na técnica de bruços parece ter características diferentes quando comparados os dados dos dois métodos de reconstrução cinemática (DP e PS)

Training evaluation in male age-group swimmers

Monitoring the training process represents an important task during sports preparation. However, not always the applied protocols help to address the coaches’ concerns, namely regarding its complexity and difficulty to be used in large samples. Therefore, the aim of this study was to apply a simple protocol to control the training process in a group of male age-group swimmer

100m and 200m front crawl performance prediction based on anthropometric and physiological measurements

Background: The identification of the variables that are able to predict swimming performance is one of the main purposes of the “swimming science” community. Research question: The aims of the study were: (i) to compare the anthropometric and physiological profiles of 100m and 200m front crawl swimmers and; (ii) to identify anthropometric and physiological variables that account for the prediction of the swimming performance at the 100m and 200m front crawl events. Methods: Twenty-six male swimmers were divided in two groups (12 for 100m group and 14 to 200m group). The swimmers’ personal best performance for the 100m and the 200m front crawl was converted to FINA points. The subjects performed a graded swimming test and an all-out test (100 or 200m maximal swims) in different days, in which physiological measures were evaluated. Forward step-by-step linear regression models were computed to predict swimming performance. The subjects’ performances (season best and all-out test) were taken as dependent variables. The age, physiological and anthropometric measures were selected as independent variables. Results: Anthropometric and physiological profiles of 100 and 200m swimmers are different and the mean oxygen uptake during exercise combined with training experience may explain 200m front crawl best season performance with a high precision (≈2% error). The models computed were able to predict from 44 % (i.e. 200m all-out bout) to 61 % (i.e. 200m season best) swimming performance. Predictive power of the models was less accurate in the 100m event (error > 10%). Conclusions: The authors conclude that the extent to which the physiological and anthropometric variables combine to predict performance probable is group-specific

Longitudinal assessment of elite swimmers performance leading to 2008 Beijing Olympic Games

The aim of this research was to track and analyze the stability of 400-m freestyle performance throughout elite swimmers preparation to the 2008 Beijing Olympic Game

Effects of musical cadence in the acute physiologic adaptations to head-out aquatic exercises

The purpose of this study was to analyze the relationships between musical cadence and the physiologic adaptations to basic head-out aquatic exercises. Fifteen young and clinically healthy women performed, immersed to the breast, a cardiovascular aquatic exercise called the ‘‘rocking horse.’’ The study design included an intermittent and progressive protocol starting at a 90 b min21 rhythm and increasing every 6 minutes, by 15 b min21, up to 195 b min21 or exhaustion. The rating of perceived effort (RPE) at the maximal heart rate achieved during each bout (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), and the blood lactate concentration ([La-]) were evaluated. The musical cadence was also calculated at 4 mmol L21 of blood lactate (R4), the RPE at R4 (RPE@R4), the HR at R4 (HR@R4), and the %HRmax at R4 (%HRmax@R4). Strong relationships were verified between the musical cadence and the RPE (R2 = 0.85; p , 0.01), the HRmax (R2 = 0.66; p , 0.01), the %HRmax (R2 = 0.61; p , 0.01), and the [La-] (R2 = 0.54; p , 0.01). The R4 was 148.13 6 17.53 b min21, the RPE@R4 was 14.53 6 2.53, the HR@R4 was 169.33 6 12.06 b min21, and the %HRmax@R4 was 85.53 6 5.72%. The main conclusion is that increasing musical cadence created an increase in the physiologic response. Therefore, instructors must choose musical cadences according to the goals of the session they are conducting to achieve the desired intensity

Longitudinal assessment of swimming performance in the 200 m freestyle event

Several studies have been carried out in order to identify the factors that can predict swimming performance. However, all these studies only analyzed determinant factors in a single moment. It was not taken into account the longitudinal stability and changes, as a result of individual development, new training methods and technological sophistication