Personalized body segment inertia parameters using 3D body scanner images

XV International Symposium on 3-D Analysis of Human Movement, MANCHESTER, ROYAUME-UNI, 03-/07/2018 - 06/07/2018Personalized values of Body Segment Inertia Parameters (BSIP) are necessary to perform dynamic analysis of human movement (e.g. trajectory of the whole body centre of mass trajectory for stability analysis, joint torques / muscular forces estimations, etc.). BSIPs are usually estimated using regressions derived from anthropometric tables (AT) [1]. However, these tables are usually not adapted to atypical populations (children, elderly, obese persons, individuals with prostheses, etc.) that are classically of interest. An alternative consists in estimating BSIPs from segments' volumes assuming a uniform density. This alternative is of growing interest as: 1) it would be suitable even for populations with atypical body mass repartition; 2) 3D body shapes acquisition has recently became easier and cheaper thanks to the developments of low-cost 3D scanners [2]. However, there are still some issues to makes this measurement (3D point cloud of the external shape) usable in the context of movement analysis with minimal intervention. The main issue is the segmentation of the whole body external shape into body segments with relevant local coordinate systems (LCS) and anatomical landmarks (AL) [3]

New methods to analyse fragmentation mechanisms of precipitated silicas

International audiencePrecipitated silica is traditionally used as reinforcing filler in rubber applications. In pneumatic manufacture, it offers several advantages compared to carbon black. Indeed, in tyres treads, precipitated silica can yield a lower rolling resistance and better wet grip at equal wear resistance than carbon black. The development of a new method to study the fragmentation mechanism of precipitated silica is investigated. Usually, the dispersion of granules is done in high viscous media (elastomer or oils). In this paper, the study is carried out in a friendlier medium (air or water)

Internal structure and fragmentation kinetics of silica granules

International audienceTo improve the mechanical properties of tires, silica granules can be incorporated into the elastomer as well as carbon black. Ideally, the fragmentation of the granules in the elastomer must be obtained with low mechanical stresses and lead to very small fragments distributed homogeneously in the material. On the other hand, granules must present a sufficient cohesion, in order to avoid the generation of fine particles during handling operations. Thus it appears necessary to control the mechanical strength of granules and the mechanism of their fragmentation. In this experimental study, we investigated the fragmentation of silica granules of 250 microns produced by spray drying. For this, we characterized by granulometry the evolution of the Particle Size Distribution of silica powder in water. The granules were suspended in water and submitted to ultrasounds. This treatment is used to create the fragmentation that occurs by viscous shearing in industrial rubber processing. A core-shell structure, characteristic of granules obtained by atomization process, was observed by SEM. Furthermore, by varying the intensity of mechanical stress, the multi-scale structure of granules was evidenced as well as the existence of different regimes of fragmentation. The kinetics of fragmentation was experimentally followed on two grades of silica that showed significant differences in their behavior during the fragmentation process

Low statistical power in biomedical science:a review of three human research domains

Studies with low statistical power increase the likelihood that a statistically significant finding represents a false positive result. We conducted a review of meta-analyses of studies investigating the association of biological, environmental or cognitive parameters with neurological, psychiatric and somatic diseases, excluding treatment studies, in order to estimate the average statistical power across these domains. Taking the effect size indicated by a meta-analysis as the best estimate of the likely true effect size, and assuming a threshold for declaring statistical significance of 5%, we found that approximately 50% of studies have statistical power in the 0–10% or 11–20% range, well below the minimum of 80% that is often considered conventional. Studies with low statistical power appear to be common in the biomedical sciences, at least in the specific subject areas captured by our search strategy. However, we also observe evidence that this depends in part on research methodology, with candidate gene studies showing very low average power and studies using cognitive/behavioural measures showing high average power. This warrants further investigation

The pro-region of the Kex2 endoprotease of Saccharomyces cerevisiae is removed by self-processing

AbstractWe have produced in the baculovirus/insect cells expression system a soluble secreted form of the Saccharomyces cerevisiae Kex2 endoprotease. This secreted enzyme was purified and its NH2-terminal sequence determined. The NH2-terminal sequence started at residue Leu109 of the sequence deduced from the KEX2 gene nucleotide sequence, showing that the Kex2 enzyme is produced as a proenzyme. Residue Leu109 is preceded by a pair of basic amino acid residues (Lys107-Arg108) which is a potential processing site for the Kex2 endopeptidase. Futhermore, expression of an inactive form of this truncated enzyme resulted in the production of a protein with a higher molecular weight. These observations suggest that the pro-region of Kex2 endoprotease is removed by a self-processing event

The generalizability of empirically derived syndromes of collateral-reported elder psychopathology across 11 societies

The purpose of this study was to test whether a syndrome model of elder psy chopathology derived from collateral ratings, such as from spouses and adult chil dren, in the United States would be generalizable in 11 other societies. Societiesrepresented South America, Asia, and Europe. The Older Adult Behavior Checklist(OABCL) was completed by collateral informants for 6141 60- to 102-year-olds. Thetested model comprised syndromes designated as Anxious/Depressed, Worries,Somatic Complaints, Functional Impairment, Memory/Cognition Problems, ThoughtProblems, and Irritable/Disinhibited. The model was tested using confirmatoryfactor analyses in each society separately. The primary model fit index showed agood fit for all societies, while the secondary model fit indices showed acceptable toa good fit for all societies. The items loaded strongly on their respective factors,with a median item loading of 0.69 across the 11 societies. By syndrome, the overallmedian item loadings ranged from 0.47 for Worries to 0.77 for Functional Impair ment. The OABCL syndrome structure was thus generalizable across the testedsocieties. The OABCL can be used for broad assessment of psychopathology forelders of diverse backgrounds in nursing services and research

Computing solutions of linear Mahler equations

International audienceMahler equations relate evaluations of the same function $f$ at iterated $b$th powers of the variable. They arise in particular in the study of automatic sequences and in the complexity analysis of divide-and-conquer algorithms. Recently, the problem of solving Mahler equations in closed form has occurred in connection with number-theoretic questions. A difficulty in the manipulation of Mahler equations is the exponential blow-up of degrees when applying a Mahler operator to a polynomial. In this work, we present algorithms for solving linear Mahler equations for series, polynomials, and rational functions, and get polynomial-time complexity under a mild assumption. Incidentally, we develop an algorithm for computing the gcrd of a family of linear Mahler operators