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See detailThe influence of isoinertial-pneumatic ratio on force-velocity-power relationships
Jidovtseff, Boris ULg; Avrillon, Simon; Hug, François et al

Conference (2016, November 29)

Introduction: Isoinertial contractions are effective to generate maximal force during the initiation of the movement whereas they do not provide an appropriate training stimulus to generate force once ... [more ▼]

Introduction: Isoinertial contractions are effective to generate maximal force during the initiation of the movement whereas they do not provide an appropriate training stimulus to generate force once accelerative phase has been developed (1). Pneumatic resistance is one alternative that has been developed to overcome the aforementioned limitations associated with isoinertial contractions. This technique allow higher initial velocity and reduce the decrease of force towards the end of the concentric phase (1). There is some training interest by combining isoinertial and pneumatic loading. The aim of this study was to determine how different isoinertial-pneumatic ratio influence the force-velocity-power relationships during bench-press. Methods: Fifteen participants performed bench press at 30%, 45%, 60%, 75%, and 90% of their 1RM, with five isoinertial(I)-pneumatic(P) resistance ratio : 100%I/0%P, 75%I/25%P, 50%I/50%P, 25%I/75%P, and 0%I/100%P. Velocity, force and power were assessed using a linear transducer and mechanical parameters measured by the pneumatic ergometer. Force-, velocity- and power-time patterns were averaged over the push-off phase to build the corresponding force-velocity and power-velocity relationships for each resistance ratio. Results: The increase in pneumatic part in resistance ratio elicited higher movement velocity and lower force level from 0% to 80% of the concentric phase. The increase in isoinertial part in resistance balance resulted in higher velocity towards the end of the movement. As a consequence, the use of isoinertial resistance oriented the force-velocity relationship towards force, whereas pneumatic resistance elicited a more velocity-oriented profile. Conclusion: Pneumatic-oriented resistance could be used to develop initial velocity and force towards the end of the push-off. Isoinertial-oriented resistance should be used to develop maximal force and maximal power. Resistance modality could be modulated according to training objectives. Références : 1. Frost et al. A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance. Eur J Appl Physiol. 2008;104:937-56. [less ▲]

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See detailInfluence of jumping strategy on kinetic and kinematic variables
Jidovtseff, Boris ULg; Quievre, Jacques; Harris Nigel et al

in Journal of sports medicine and physical fitness (2014), 54

Aim: Different jumping strategies can be used during plyometric training. Understanding how manipulating variables such as the counter-movement, flexion amplitude, the drop and the load could influence ... [more ▼]

Aim: Different jumping strategies can be used during plyometric training. Understanding how manipulating variables such as the counter-movement, flexion amplitude, the drop and the load could influence neuromuscular adaptation would be beneficial for coaches and athletes. The purpose of this study was to analyze how these variations in the vertical jump influenced kinematic and kinetic parameters as measured by a force platform. Methods: Ten male subjects performed, eight kinds of vertical jumps on a force platform : (1) squat jump (SJ); (2) shallow counter-movement jump (S-CMJ); (3) natural counter-movement jump (N-CMJ); (4) deep counter-movement jump (D-CMJ); (5) loaded (20kg) counter-movement jump (20-CMJ); (6) shallow drop jump (S-DJ); (7) deep drop jump (D-DJ); (8) six consecutive jump test (6CJ). Customised Labview software was used to calculate time, displacement, velocity, acceleration, force, power, impulse and stiffness. After statistical analysis, jumping variables were grouped to achieve spécific training objectives. Results: The mechanical parameters were largely influenced by the jump strategy, all the deep jumps produced superior jump heights and concentric velocities as compared to the shallow jumps. The exercises associated with greater power outputs were the S-DJ (5386±1095w) and 6CJ (5795±1365w) that involved short impulse durations and very high accelerations. The greatest values of muscle stiffness were not recorded during the highest vertical jumps, meaning that stiffness is not critical for jumping high. Conclusion: This study gives an overview of what is changing when we manipulate jumping variables and instructions given to the athletes. Plyometric exercises should be carefully selected according to the sport and specific individual needs. [less ▲]

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See detailThe influence of laboratory-induced Meld score differences on liver allocation: more reality than myth.
Schouten, J. N.; Francque, S.; Van Vlierberghe, H. et al

in Clinical Transplantation (2012), 26(1), 62-70

Background: Liver allocation in Eurotransplant (ET) is based on the MELD score. Interlaboratory MELD score differences in INR and creatinine determination have been reported. The clinical implication of ... [more ▼]

Background: Liver allocation in Eurotransplant (ET) is based on the MELD score. Interlaboratory MELD score differences in INR and creatinine determination have been reported. The clinical implication of this observation has not been demonstrated. Methods: MELD scores were calculated in 66 patients with liver cirrhosis using bilirubin, creatinine, and INR analyzed in six liver transplant centers. Based on allocation results of ET, patients transplanted from December 2006 to June 2007 were divided according to MELD score in four groups. For each group, the influence of the match MELD on the probability of receiving a transplant was studied (Cox proportional hazards model). Results: Laboratory-dependent significant differences in MELD score were demonstrated. Cox proportional hazards model showed a significant association between MELD score and the probability of organ allocation. The unadjusted hazard ratio for receiving a liver transplant was significantly different between group 2 and group 4 (group 2: MELD 19–24; group 4: MELD > 30). Conclusion: Laboratory-dependent significant differences in MELD score were observed between the six transplant centers. We demonstrated a significant association between the MELD score and the probability of organ allocation. The observed interlaboratory variation might yield a significant difference in organ allocation in patients with high MELD scores. [less ▲]

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See detailInfluence of laminin and fibroblasts upon colony formation by B16 melanoma cells
De Leval, Laurence; Leyh, Philippe; Grégoire, Dominique et al

Poster (1990, September)

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See detailInfluence of laminin and fibroblasts upon colony formation in the mouse by B16 melanoma cell spheroids
de Leval, Laurence; Leyh, Philippe; Grégoire, Dominique et al

in Anticancer Research (1990), 10(5B), 1447

Detailed reference viewed: 23 (5 ULg)
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See detailInfluence of laminin or fibroblasts upon colony formation in the mouse by B16 melanoma cell spheroids: a morphometric analysis.
Coucke, P.; de Leval, Laurence ULg; Leyh, P. et al

in In Vivo (Athens, Greece) (1992), 6(2), 119-24

By microscopical observation and using an original morphometric method, we analyzed on histological sections the rate of lung colony formation after the intravenous injection into the mouse of B16 ... [more ▼]

By microscopical observation and using an original morphometric method, we analyzed on histological sections the rate of lung colony formation after the intravenous injection into the mouse of B16 melanoma cells previously cultivated in vitro as aggregates. After the injection of B16 pure spheroids, superficial lung colonies were more numerous than internal lung colonies. After the injection of mixed spheroids (B16 + 3T3 fibroblasts), the size of colony sections was increased. Addition of laminin to pure or mixed spheroids decreased the size of colony sections but increased the number of internal lung colonies. [less ▲]

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See detailThe influence of lateral bending restrain in numerical and experimental evaluation of lateral buckling resistance design moment of steel I-beams at elevated temperatures
Piloto, P. A. G.; Vila Real, P. M. M.; Franssen, Jean-Marc ULg

in Proceedings of the 5° Congreso Interamericano de Computacion Applicada a la Industria de Procesos (CAIP'2001) (2001)

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See detailThe influence of level of care on admission to neonatal care for babies of low-risk nullipara
Le Ray, C.; Zeitlin, J.; Jarreau, P. H. et al

in European Journal of Obstetrics & Gynecology & Reproductive Biology (2009), 144

Objective To analyze the risk of admission to neonatal care for newborns of low-risk nullipara and its variation with level of care of the maternity unit. Study design The sample included infants born to ... [more ▼]

Objective To analyze the risk of admission to neonatal care for newborns of low-risk nullipara and its variation with level of care of the maternity unit. Study design The sample included infants born to low-risk nulliparas from the PREMODA study of 138 French maternity units (n = 3652). Medical records of children admitted to neonatal care were reviewed to determine the reasons for admission and the severity of morbidity. The risk factors associated with admission to neonatal care, including maternal, infant and delivery unit characteristics, were studied by univariable analysis, followed by a multivariable analysis using a multilevel logistic model. Results The newborns of 3.5% (n = 129) of the nulliparous mothers at low risk were admitted to neonatal care at birth. The two principal reasons were infections (57%) and respiratory diseases (19%). Babies born in level 2 maternity units were twice as likely to be admitted to neonatal care as those born in level 1 units (ORa = 2.0 [1.1–3.7]) and those born in level 3 units, 1.5 times more often, although this was not statistically significant (ORa = 1.5 [0.8–2.8]). Babies admitted to neonatal care after delivery in level 1 had more severe morbidity (n = 4, 26.7%) than those admitted from level 2 (n = 4, 5.7%) or level 3 (n = 3, 6.8%) facilities (p = 0.046). Conclusion In low-risk populations, the level of care could have an influence on the decision to admit babies to neonatal care at birth. These findings add to the on-going debate about the optimal organization of care for women at low obstetrical risk. [less ▲]

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See detailInfluence of Lianol Solapro on sow milk production and piglet weight gain
Wavreille, José; Planchon, Viviane; Renaville, Robert ULg et al

in 21 Inter. Pig Vet Society Congress (2010)

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See detailInfluence of lignin in Reticulitermes santonensis: symbiotic interations investigated through proteomics
Bauwens, Julien ULg; Tarayre, Cédric ULg; Brasseur, Catherine ULg et al

in Symbiosis (2013)

The gut of lower termites is populated by numerous microbial species belonging to prokaryotes, fungi, yeasts and protists. These micro-organisms are organized in a complex symbiotic system, interacting ... [more ▼]

The gut of lower termites is populated by numerous microbial species belonging to prokaryotes, fungi, yeasts and protists. These micro-organisms are organized in a complex symbiotic system, interacting together and with the insect host. Their likely ability to degrade ligno-cellulosic compounds could lead to improvements in second generation biofuels production. Lignin elimination represents a critical point as this polymer significantly interferes with industrial process of cellulose. Although host produces its own lignin-degrading enzymes, some symbionts may participate in digestion of lignin and its degradation products in termite gut. Here, we compared gut proteomes from R. santonensis after rearing on artificial diets composed of cellulose with and without lignin. The effect of lignin in artificial diets on different parts of the digestive tract was compared through liquid chromatography associated with tandem mass spectrometry (LC-MS/MS) experiments. Enzymatic assays were performed to characterize activities present in R. santonensis digestive tract after feeding on artificial diets. Microscopic observations of microbial communities provided some information on population balances after feeding experiment. [less ▲]

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See detailInfluence of lipopeptides of Bacillus subtilis on the surface hydrophobicity of steel and Teflon.
Shakerifard, P.; Gancel, F.; Faille, C. et al

Poster (2007)

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See detailInfluence of liquid oxygen environment on the tribological behaviour of PCTFE/440C steel contact
Cautain, Satia; Duquenne, Marc ULg; Robbe-Valloire, François et al

in Space Propulsion 2012 (2012)

This article proposes a tribological study of contact between polychlorotrifluoroethylene (PCTFE) and 440C steel. The tests are performed on a pin-on-disc cryotribometer specifically designed to overcome ... [more ▼]

This article proposes a tribological study of contact between polychlorotrifluoroethylene (PCTFE) and 440C steel. The tests are performed on a pin-on-disc cryotribometer specifically designed to overcome the additional issues due to the use of cryogenic fluid. Test parameters such as speed, contact pressure and sliding distance are kept the same for the whole campaign, leaving the environment as the only variable. This study focuses on the analysis of friction, wear of PCTFE pin and appearance of disk after tests. The test results show the influence of the state of environment (gas or liquid), its temperature and its reactivity (neutral or oxidative) on the contact behaviour. [less ▲]

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See detailInfluence of liquid viscosity on separation efficiency of structured packings – modelling approach based on X-ray tomography investigations
Janzen, Anna; Steube, Julia; Crine, Michel ULg et al

in Proceedings (2014)

The objectives of this work are the investigation of liquid flow morphology inside a structured packing using X-ray tomography and the development of a modelling approach based on hydrodynamic analogy ... [more ▼]

The objectives of this work are the investigation of liquid flow morphology inside a structured packing using X-ray tomography and the development of a modelling approach based on hydrodynamic analogy between the real complex flow patterns and simplified fluid-dynamic elements. To study the influence of viscosity, water and mixtures of water and glycerine with varying glycerine fraction are used as working liquids. X-ray tomography is applied to determine the spatial distribution of liquid in the cross-section of a column filled with MellapakPlus 752.Y packing elements. The resulting images are used to evaluate liquid hold-up, gas-liquid interfacial area and to analyse liquid morphology. Liquid flow patterns (film flow, contact-point liquid, flooded regions) are identified, and the fraction of liquid within each flow pattern depending on flow rate and liquid viscosity is determined. The results of the liquid flow morphology analysis are used to develop a hydrodynamic analogy model. To implement the gas-liquid contact area and the flooded regions into this model, the packing is represented as a bundle of dry, filled and irrigated cylindrical channels, while the ratio between different type channels is determined from the analysis of tomographic images. This simplified hydrodynamic description allows a direct application of rigorous partial differential transport equations, and their solution yields local concentration fields which are used for the evaluation of the separation efficiency. The new modelling approach is validated by comparison with separation efficiency data obtained from experiments with CO2 desorption from saturated water-glycerine mixtures into air. The presented modelling approach is capable of predicting the influence of viscosity on separation efficiency of columns filled with structured packings. [less ▲]

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See detailThe influence of lithology on the mechanical strength and porosity of terra-cotta, the case study of Marrakech region (Morocco).
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; Collin, Frédéric ULg et al

Poster (2015, May 19)

The ceramic pastes in Marrakech region are prepared on the base of six types of raw materials of different lithologies. Various products are manufactured. The production consists of cooking utensils ... [more ▼]

The ceramic pastes in Marrakech region are prepared on the base of six types of raw materials of different lithologies. Various products are manufactured. The production consists of cooking utensils (based on schist, colluviums, quartzose sand and silt), decoration products (based on argillite, washing residues and soil), vases and gourds products (based on schist and soil), tiles (based on silt decantation) and traditional dishes (based on soil and argillite). In this study we elaborate bricks from the different raw material and we evaluate some of their physical properties after firing at 1050°C. In particular we measure the porosity to water and the mechanical strength of all the fired bricks. The aim is to compare the final product quality according to the origin (lithology) of the clayey raw material of the ceramic pastes. Based on our experiments, the bricks of the lower compressive strength (CS) and of the lower flexural strength (FS) are those based on sand (CS = 39 MPa; FS = 7 MPa), on silt decantation (CS = 25 to 39 MPa; FS = 10 to 18 MPa), and on schist and colluviums (CS = 20 to 51 MPa; FS = 6 to 17 MPa). Those of the highest values are based on argillites (CS = 33 to 102 MPa; FS = 13 to 28 MPa). The other pastes are characterized by intermediate values. The porosity ranges between 5 to 27%. The bricks based on silt decantation have the greatest values (20 to 27%), whereas those based on argillite have the lower values (5 to 10%). Those physical properties are, in most cases, in agreement with the requested values of the bricks industry. We conclude that such raw materials have high perspective to manufacture structural products of high performance in mechanical strength and thermal insulation. [less ▲]

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See detailINFLUENCE OF LOCAL BUCKLING ON THE SHEAR RESISTANCE OF BOLTED CONNECTIONS FOR TUBULAR RACKING STRUCTURES
D'Antimo, Marina ULg; Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg et al

in THE INTERNATIONAL COLLOQUIUM ON STABILITY AND DUCTILITY OF STEEL STRUCTURES, Timisoara 30 May-01 June 2016 (2016, May)

The competition in the field of storage racking structures is so that companies are always look-ing for new structural solutions aiming at containing construction time and expenses. This pa-per focuses ... [more ▼]

The competition in the field of storage racking structures is so that companies are always look-ing for new structural solutions aiming at containing construction time and expenses. This pa-per focuses the bearing failure of shear joint using long bolts through thin tubular members with the purpose to check the reliability of Eurocode 3 formulation. The used hollow sections are free to buckle inward leading to a bearing resistance lower than the one predicted using EC3. In fact EC3 does not account for the possible occurrence of out-of-plane deformations in shear connection assuming that the connected plates are restrained by the bolt head and the nut. In order to investigate this phenomenon, an experimental campaign has been developed, a FE model Abaqus/CAE has been validated and a parametric study has been performed. The present paper introduces the conducted investigations. [less ▲]

Detailed reference viewed: 48 (5 ULg)