24 research outputs found

    Time course of muscle activation, energetics and mechanics of running in minimalist and traditional cushioned shoes during level running.

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    The study aimed to compare the ankle muscles activation, biomechanics and energetics of running in male runners during submaximal level run using minimalist (MinRS) and traditional cushioned (TrdRS) running shoes. During 45-min running in MinRS and TrdRS, the ankle muscles pre- and co-activation, biomechanics, and energetics of running of 16 male endurance runners (25.5 ± 3.5 yr) were assessed using surface electromyography (tibialis anterior and gastrocnemius lateralis), instrumented treadmill and indirect calorimetry, respectively. The net energy cost of running (C <sub>r</sub> ) was similar for both conditions (P = 0.25) with a significant increase over time (P < 0.0001). Step frequency (P < 0.001), and total mechanical work (P = 0.001) were significantly higher in MinRS than in TrdRS with no evolution over time (P = 0.28 and P = 0.85, respectively). The ankle muscles pre- and co-activation during the contact phase did not differ between the two shoe conditions (P ≥ 0.33) or over time (P ≥ 0.15). In conclusion, during 45-min running, Cr and muscle pre- and co-activation were not significantly different between MinRS and TrdRS with significantly higher step frequency and total mechanical work noted in the former than in the latter. Moreover, C <sub>r</sub> significantly increased during the 45-min trial in both shoe conditions along with no significant change over time in muscle activation and biomechanical variables

    An explicit KO-degree map and applications

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    The goal of this note is to study the analog in unstable A1{{\mathbb A}^1}-homotopy theory of the unit map from the motivic sphere spectrum to the Hermitian K-theory spectrum, i.e., the degree map in Hermitian K-theory. We show that "Suslin matrices", which are explicit maps from odd dimensional split smooth affine quadrics to geometric models of the spaces appearing in Bott periodicity in Hermitian K-theory, stabilize in a suitable sense to the unit map. As applications, we deduce that KiMW(F)=GWii(F)K^{MW}_i(F) = GW^i_i(F) for i3i \leq 3, which can be thought of as an extension of Matsumoto's celebrated theorem describing K2K_2 of a field. These results provide the first step in a program aimed at computing the sheaf πnA1(An0)\pi_{n}^{{\mathbb A}^1}({\mathbb A}^n \setminus 0) for n4n \geq 4.Comment: 36 Pages, Final version, to appear Journal of Topolog

    Sclérose tubéreuse de Bourneville et polypose colique

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    Tuberous sclerosis is an autosomal dominant genetic disorder that is characterized by epilepsy, mental retardation and facial angiofibromas. Usually, the disease is diagnosed in childhood but there are frustrates form of tuberous sclerosis with or without genetic mutation. This clinical case about a man who is diagnosed a colonic polyposis, a rectal adenocarcinoma and a tuberous sclerosis. .SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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