Track D Social Science, Human Rights and Political Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

Écoulements uniformes et graduellement variés en lit composé versus couches de mélanges libres

36th IAHR World Congress, La Haye, NLD, 28-/06/2015 - 03/07/2015International audienceMixing layers associated with uniform and gradually varied flows (GVF) in compound channel are experimentally investigated in two flumes, featuring a rectangular or a trapezoidal main channel (MC). These shear layers are compared with free mixing layers. Starting with uniform flow, the GVF are generated by an imbalance in the upstream discharge distribution between the floodplain (FP) and the MC. The GVF are longitudinally evolving under the influence of four external forcings: (i) a two-stage geometry, (ii) a varying vertical flow confinement (quantified by the relative flow depth, Dr = hf / hm, where hf and hm are the flow depths in the FP and MC); (iii) a variable lateral depth-averaged mean flow; (iv) a variable velocity ratio, l = Us/(2Uc), where Us = Ud2-Ud1 is the velocity difference, Uc = 0.5(Ud1+Ud2) is the mean velocity across the mixing layer, Ud1 and Ud2 are the depth-averaged velocities outside the mixing layer in the FP and MC, respectively. In the case of weakly or moderately sheared flows (l < 0.3 - 0.35), the peak values of scaled depth averaged Reynolds-stress, denoted Max (gd), are independent of l, but increase with a decrease in flow confinement, to reach the maximum values observed for free mixing layers. In the case of highly sheared flows (l > 0.3 - 0.35), the values of Max (gd) become independent of the flow confinement as l increases, reaching values that can be greater than the ones observed for free mixing layers. Despite the flow confinement, the high values of l trigger the development of 2D large coherent structures without interaction with the 3D bed-induced turbulence. Lastly, with nearly constant values of l and Dr, it was found that the scaled shear-layer turbulence was mainly dictated by the lateral flow. For both uniform flows and test cases with a lateral flow to the FP, the Rayleigh's inflection point criterion is fulfilled. This gives rise to large 2D structures and high values of Max (gd). By contrast, for test cases with a significant lateral flow to the MC, the convex velocity profiles without inflection-point are associated with low levels of Max (gd). Lastly, the trapezoidal MC was found to enhance the turbulent exchange compared with the rectangular one

The effect of countermovement on force production capacity depends on extension velocity: A study of alpine skiers and sprinters

In jumping, countermovement increases net propulsive force and improves performance. We aimed to test whether this countermovement effect is velocity specific and examine the degree to which this varies between athletes, sports or performance levels. Force-velocity profiles were compiled in high-level skiers (N= 23) and sprinters (N= 30), with their performance represented in their overall world ranking and season-best 100 m time, respectively. Different ratios between force-velocity variables were computed from squat and countermovement jumps (smaller = less effect): jump height (CRh ), maximum power (CRP ), force (CRF ), and velocity (CRv ). Countermovement effect differed per velocity (inverse relationship between CRF and CRv, r(s) = -0.74, p .05). 33% of the variance in skiers' performance level was explained by greater maximum force and a lower CRF (i.e., high explosiveness at low-velocities without countermovement), without an association for sprinters. Countermovement effect appears specific to movement velocity, sport and athlete level. Consequently, we advise sports-specific assessment, and potentially training to reduce the countermovement effect per the relevant velocity

Distal truncation of KCC3 in non-French Canadian HMSN/ACC families.

Item does not contain fulltextBACKGROUND: Hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC) is a severe and progressive autosomal recessive polyneuropathy. Mutations in the potassium-chloride cotransporter 3 gene (KCC3) were identified as responsible for HMSN/ACC in the French Canadian (FC) population. In the present study, the authors were interested in finding new mutations in non-FC populations, assessing the activity of mutant proteins and refining genotype-phenotype correlations. METHODS: The authors screened KCC3 for mutations using direct sequencing in six non-FC HMSN/ACC families. They then assessed the functionality of the most common mutant protein using a flux assay in Xenopus laevis oocytes. RESULTS: The authors identified mutations in exon 22 of KCC3: a novel mutation (del + 2994-3003; E1015X) in one family, as well as a known mutation (3031C-->T; R1011X) found in five unrelated families and associated with two different haplotypes. The function of the cotransporter was abolished, although a limited amount of mutant proteins were correctly localized at the membrane. CONCLUSIONS: KCC3 mutations in exon 22 constitute a recurrent mutation site for hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC), regardless of ethnic origin, and are the most common cause of HMSN/ACC in the non-French Canadian (FC) families analyzed so far. Therefore, for genetic analysis, exon 22 screening should be prioritized in non-FC populations. Finally, the R1011X mutation leads to the abrogation of KCC3's function in Xenopus laevis oocytes, likely due to impaired transit of the cotransporter