Trunk Inclination Estimate During the Sprint Start Using an Inertial Measurement Unit: A Validation Study

The proper execution of the sprint start is crucial in determining the performance during a sprint race. In this respect, when moving from the crouch to the upright position, trunk kinematics is a key element. The purpose of this study was to validate the use of a trunk-mounted inertial measurement unit (IMU) in estimating the trunk inclination and angular velocity in the sagittal plane during the sprint start. In-laboratory sprint starts were performed by five sprinters. The local acceleration and angular velocity components provided by the IMU were processed using an adaptive Kalman filter. The accuracy of the IMU inclination estimate and its consistency with trunk inclination were assessed using reference stereophotogrammetric measurements. A Bland-Altman analysis, carried out using parameters (minimum, maximum, and mean values) extracted from the time histories of the estimated variables, and curve similarity analysis (correlation coefficient > 0.99, root mean square difference < 7 deg) indicated the agreement between reference and IMU estimates, opening a promising scenario for an accurate in-field use of IMUs for sprint start performance assessment

La construction de sens dans l’enseignement des mathématiques Comparaison des programmes et de manuels brésiliens et français concernant l’introduction de la multiplicatio

Dissertação (mestrado)—Universidade de Brasília, Instituto de Letras, Departamento de Teoria Literária e Literaturas, Programa de Pós-Graduação em Literatura, 2020.Esta pesquisa observa como os livros didáticos brasileiros e franceses, interfaces estáveis entre currículo prescrito e currículo real, oferecem uma educação matemática que permite aos alunos construir sentido. Depois de extrair dos programas os parâmetros que favorecem a compreensão em matemática, ela compara a ordem e a maneira de abordar o campo conceitual multiplicativo, revelando associações variáveis com adição, divisão e com a necessidade real de uma operação nova. A análise quantitativa de todas as instruções permite observar a raridade das configurações retangulares em favor de situações de proporção simples, mas também a variabilidade de usos e de riqueza da contextualização das situações. O estudo então levanta que embora se refiram principalmente à vida cotidiana, os autores não se baseam muito em situações adidáticas verdadeiras. Os dados matemáticas, muitas vezes orais na França, têm formas variadas no Brasil, com maior envolvimento dos sentidos. Por fim, a análise dos objetivos perseguidos pelas instruções revela uma padronização nacional e / ou cultural do esquema educacional seguido pelos livros didáticos, ao mesmo tempo que reúne livros didáticos entre países que fazem as pessoas pesquisarem mais do que aplicar. Em suma, o que mais difere entre os países diz respeito essencialmente à forma dos conteúdos e às propostas além do livro do aluno e, portanto, o estudo levanta a questão do que se espera de um livro didático na educação.This research studies how Brazilian and French textbooks, as stable interfaces between prescribed and real curricula, offer mathematics education that allows student to construct meaning. After the programs’ extraction of parameters helping comprehension in mathematics, it compares the order and the manner of approaching the multiplicative conceptual field, revealing variable associations with addition, division, and with a real need for a new mathematical operation. The quantitative analysis of all instructions makes it possible to observe the rarity of rectangular configurations in favor of situations of simple proportion, but also the variability of uses and of richness of contextualization of the statements. The study points out that, although they mostly deal with everyday life, the authors do not rely very often on real adidactic situations. Often oral in France, the data for calculating have more varied forms in Brazil, where the senses are more involved. Finally, the analysis of the objectives pursued by the instructions reveals a national and/or cultural standardization of the educational scheme followed by the textbooks, while bringing together from both countries textbooks that lead more to research than to application. All in all, what differs the most between countries concerns essentially the form of contents and the proposals beyond the pupil’s file, therefore the study raises the question of what is expected of a school textbook in education.Cette recherche observe comment des manuels scolaires brésiliens et français, interfaces stables entre curriculum prescrit et curriculum réel, proposent un enseignement des mathématiques qui permette aux élèves de construire du sens. Après avoir extrait des programmes les paramètres favorisant la compréhension en mathématiques, elle compare l’ordre et la manière d’approcher le champ conceptuel multiplicatif, révélant des associations variables avec l’addition, la division, et avec un réel besoin d’une nouvelle opération. L’analyse quantitative de l’ensemble des consignes permet ensuite d’observer la rareté des configurations rectangulaires au profit des situations de proportion simple, mais aussi la variabilité des usages et de la richesse de contextualisation des énoncés. L’étude soulève alors que, bien qu’évoquant majoritairement la vie quotidienne, les auteurs ne se basent que peu sur de véritables situations adidactiques. Les données des situations, bien souvent orales en France, ont des formes plus variées au Brésil, où les sens sont plus sollicités. Enfin, l’analyse des objectifs poursuivis par les consignes dévoile une standardisation nationale et/ou culturelle du schéma pédagogique suivi par les manuels, tout en rapprochant entre les pays des manuels qui font plus rechercher qu’appliquer. Au total, ce qui diffère le plus entre les pays concerne essentiellement la forme des contenus et les propositions au-delà du fichier de l’élève et l’étude soulève donc la question de ce que l’on attend d’un manuel scolaire dans l’enseignement

Selection of hardwood saplings by European roe deer: Effects of variation in the availability of palatable species and of understory vegetation

L'alimentation du chevreuil (Capreolus capreolus) dans les forêts européennes de production a des conséquences financières importantes. Le chêne (Quercus robur, Q. pedunculatus) et le charme (Carpinus betulus) font partie des espèces communément consommées et souffrent de niveaux de dégâts élevés. Dans cet article, nous testons l'hypothèse que les préférences alimentaires du chevreuil dépendent de la fréquence de présence des espèces. Dans la première expérience, le charme et le cornouiller (Cornus sanguinea) sont offerts en proportions variables de 2/8 à 8/2 : le charme est préféré et le degré de préférence n'est pas affecté par son abondance relative. Dans la deuxième expérience, le chêne, le hêtre (Fagus sylvatica) et l'érable (Acer pseudoplatanus) sont offerts dans des conditions plus naturelles (plantation) avec une végétation d'accompagnement abondante ou rare. La consommation de chêne diminue quand la végétation d'accompagnement est abondante; mais son abondance relative par rapport aux autres plants n'a pas d'effet sur le degré de préférence. La sélection alimentaire chez le chevreuil n'apparaît pas être dépendante de la fréquence des espèces : certaines conclusions sont tirées pour la gestion des plantations forestières

Slimming Brick Cache Strategies for Seismic Horizon Propagation Algorithms

International audienceIn this paper, we propose a new bricked cache system suitable for a particular surface propagation algorithm : seismic horizon reconstruction. The application domain of this algorithm is the interpretation of seismic volumes used, for instance, by petroleum companies for oil prospecting. To ensure the optimality of such surface extraction, the algorithm must access randomly into the data volume. This lack of data locality imposes that the volume resides entirely in the main memory to reach decent performances. In case of volumes larger than the memory, we show that using a classical brick cache strategy can also produce good performances until a certain size. As the size of these volumes increases very quickly, and can now reach more than 200GB, we demonstrate that the performances of the classical algorithm are dramatically reduced when processed on standard workstation with a limited size of memory (currently 8GB to 16GB). In order to handle such large volumes, we introduce a new slimming brick cache strategy where bricks size evolves according to processed data : at each step of the algorithm, processed data could be removed from the cache. This new brick format allows to have a larger number of brick loaded in memory. We further improve the releasing mechanism by filling in priority the “holes” that appear in the surface during the propagation process. With this new cache strategy, horizons can be extracted into volumes that are up to 75 times the size of the available cache memory. We discuss the performances and results of this new approach applied on both synthetic and real data

Isolation of mineralizing Nestin+ Nkx6.1+ vascular muscular cells from the adult human spinal cord

<p>Abstract</p> <p>Background</p> <p>The adult central nervous system (CNS) contains different populations of immature cells that could possibly be used to repair brain and spinal cord lesions. The diversity and the properties of these cells in the human adult CNS remain to be fully explored. We previously isolated Nestin⁺Sox2⁺neural multipotential cells from the adult human spinal cord using the neurosphere method (i.e. non adherent conditions and defined medium).</p> <p>Results</p> <p>Here we report the isolation and long term propagation of another population of Nestin⁺cells from this tissue using adherent culture conditions and serum. QPCR and immunofluorescence indicated that these cells had mesenchymal features as evidenced by the expression of Snai2 and Twist1 and lack of expression of neural markers such as Sox2, Olig2 or GFAP. Indeed, these cells expressed markers typical of smooth muscle vascular cells such as Calponin, Caldesmone and Acta2 (Smooth muscle actin). These cells could not differentiate into chondrocytes, adipocytes, neuronal and glial cells, however they readily mineralized when placed in osteogenic conditions. Further characterization allowed us to identify the Nkx6.1 transcription factor as a marker for these cells. Nkx6.1 was expressed in vivo by CNS vascular muscular cells located in the parenchyma and the meninges.</p> <p>Conclusion</p> <p>Smooth muscle cells expressing Nestin and Nkx6.1 is the main cell population derived from culturing human spinal cord cells in adherent conditions with serum. Mineralization of these cells in vitro could represent a valuable model for studying calcifications of CNS vessels which are observed in pathological situations or as part of the normal aging. In addition, long term propagation of these cells will allow the study of their interaction with other CNS cells and their implication in scar formation during spinal cord injury.</p

Clinical characteristics and prognosis of osteosarcoma in young children: a retrospective series of 15 cases

<p>Abstract</p> <p>Background</p> <p>Osteosarcoma is the most common primary bone malignancy in childhood and adolescence. However, it is very rare in children under 5 years of age. Although studies in young children are limited in number, they all underline the high rate of amputation in this population, with conflicting results being recently reported regarding their prognosis.</p> <p>Methods</p> <p>To enhance knowledge on the clinical characteristics and prognosis of osteosarcoma in young children, we reviewed the medical records and histology of all children diagnosed with osteosarcoma before the age of five years and treated in SFCE (Société Française des Cancers et leucémies de l'Enfant) centers between 1980 and 2007.</p> <p>Results</p> <p>Fifteen patients from 7 centers were studied. Long bones were involved in 14 cases. Metastases were present at diagnosis in 40% of cases. The histologic type was osteoblastic in 74% of cases. Two patients had a relevant history. One child developed a second malignancy 13 years after osteosarcoma diagnosis.</p> <p>Thirteen children received preoperative chemotherapy including high-dose methotrexate, but only 36% had a good histologic response. Chemotherapy was well tolerated, apart from a case of severe late convulsive encephalopathy in a one-year-old infant. Limb salvage surgery was performed in six cases, with frequent mechanical and infectious complications and variable functional outcomes.</p> <p>Complete remission was obtained in 12 children, six of whom relapsed. With a median follow-up of 5 years, six patients were alive in remission, seven died of their disease (45%), in a broad range of 2 months to 8 years after diagnosis, two were lost to follow-up.</p> <p>Conclusions</p> <p>Osteosarcoma seems to be more aggressive in children under five years of age, and surgical management remains a challange.</p

Overview of the current use of levosimendan in France: a prospective observational cohort study

Abstract Background Following the results of randomized controlled trials on levosimendan, French health authorities requested an update of the current use and side-effects of this medication on a national scale. Method The France-LEVO registry was a prospective observational cohort study reflecting the indications, dosing regimens, and side-effects of levosimendan, as well as patient outcomes over a year. Results The patients included ( n = 602) represented 29.6% of the national yearly use of levosimendan in France. They were treated for cardiogenic shock ( n = 250, 41.5%), decompensated heart failure ( n = 127, 21.1%), cardiac surgery-related low cardiac output prophylaxis and/or treatment ( n = 86, 14.3%), and weaning from veno-arterial extracorporeal membrane oxygenation ( n = 82, 13.6%). They received 0.18 ± 0.07 µg/kg/min levosimendan over 26 ± 8 h. An initial bolus was administered in 45 patients (7.5%), 103 (17.1%) received repeated infusions, and 461 (76.6%) received inotropes and or vasoactive agents concomitantly. Hypotension was reported in 218 patients (36.2%), atrial fibrillation in 85 (14.1%), and serious adverse events in 17 (2.8%). 136 patients (22.6%) died in hospital, and 26 (4.3%) during the 90-day follow-up. Conclusions We observed that levosimendan was used in accordance with recent recommendations by French physicians. Hypotension and atrial fibrillation remained the most frequent side-effects, while serious adverse event potentially attributable to levosimendan were infrequent. The results suggest that this medication was safe and potentially associated with some benefit in the population studied

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Exécutions sommaires et massacres [La France pendant la Seconde Guerre mondiale, atlas historique]

[dans le chapitre 8 : Répressions et persécutions, p. 188-215

Approche de la répression extrajudiciaire à l'été 1944

(Collection : Seconde Guerre mondiale, n°7