On the determination of cusp points of 3-R\underline{P}R parallel manipulators

This paper investigates the cuspidal configurations of 3-RPR parallel manipulators that may appear on their singular surfaces in the joint space. Cusp points play an important role in the kinematic behavior of parallel manipulators since they make possible a non-singular change of assembly mode. In previous works, the cusp points were calculated in sections of the joint space by solving a 24th-degree polynomial without any proof that this polynomial was the only one that gives all solutions. The purpose of this study is to propose a rigorous methodology to determine the cusp points of 3-R\underline{P}R manipulators and to certify that all cusp points are found. This methodology uses the notion of discriminant varieties and resorts to Gr\"obner bases for the solutions of systems of equations

Profondeur Inconnue

With global warming threatening to transform the physical and human landscape across the planet, humans must adapt to a changed environment and possibly learn to survive in a dramatically altered landscape. Though many species, including humans, may not survive a dramatic alteration in the earth's climate, those few who do survive will be strong and possess unique abilities and adaptations. This piece explores themes of cooperation, competition, and survival in an underwater environment, where the human body must adapt to alien ways of moving

Le Valais par les dates: une chronologie des origines à nos jours

Première chronologie complète de l'histoire du Valais, elle remonte aux premières traces de l'homme (env. -30'000) et va jusqu'à la fin du XXe siècle. Le texte est disposé sur deux colonnes: une pour les repères suisses et européens, une pour les événements valaisans. Chaque événement est suivi d'une ou de plusieurs références bibliographiques. Il concerne tous les domaines: politique, économie, social, culture, religion, sport... Certains phénomènes sont développés plus longuement dans des encadrés. Une bibliographie et un index complètent le tout

The omitted variable: could DuoTest enable a new way to assess the link between individual and team performance in team-based learning?

Imagine a class of students being allowed to do their final exam twice in a row: the first time, participants do their exam individually and with closed books (Exa01); the second time, they solve the same exam in groups and with open books (Exa02). If you think that all students will get a better grade in the second exam, you would be surprised by the results. This article is part of an ongoing project to develop a method for team-based learning named Testudo. We present an assessment technique called DuoTest, which uses a mixed model to (a) analyze data from individual and group exams and (b) determine the positive (or negative) effect of each team over the individual performances. Empirical results collected from 70 students show that individual exams are a weak predictor of the group scores, whereas fixed effects associated to each team are a better predictor of Exa02

The Omitted Variable: Could DuoTest Enable a New Way to Assess Team Performance in Team-Based Learning?

This article is part of an ongoing project to develop a method for team-based learning named Testudo. We present an assessment technique called DuoTest, which allows students to do their final exam twice in a row: the first time, participants do their exam individually (Exa01); the second time, they solve the same exam in groups (Exa02). By comparing individual and group exams, the system induces the positive (or negative) effect of each team over the individual performances. Empirical results collected from 70 students show that individual exams are a reliable, although weak, predictor of the group scores (p\u3c0.10, Adj R2= 0.02). Instead, by measuring the fixed effect of each team, we obtain a better predictor of Exa02 (Adj R2= 0.71). Although additional testing is required, our guidelines address a current gap in the literature for techniques that rigorously assess the individual and team dimensions, and that are easy to implement

Prevalence and determinants of weight misperception in an urban Swiss population.

Weight misperception precludes effective management of pre-obesity and obesity, but little is known regarding its status in the Swiss population. Our study aimed to assess the prevalence and determinants of weight over- and underestimation in an adult urban Swiss population. Cross-sectional study conducted between 2009 and 2012 in the city of Lausanne. Height and weight were measured using standardised procedures. Weight perception and other socio-demographic variables were collected through questionnaires. Data from 4284 participants (2261 women, 57.5 ± 10.4 years) were analysed. Overall, almost one-fifth (18%) of participants underestimated their weight, while only 7% overestimated it. One quarter of women and half of men with overweight underestimated their weight; the corresponding values for obese subjects were 7% and 10%. Multivariate analysis showed male gender (odds ratio [OR] 3.09, 95% confidence interval [CI] 2.54-3.76), increasing age or body mass index (p-value for trend <0.001), being born in Portugal (OR 2.10, 95% CI 1.42-3.10), low education (OR 1.90, 95% CI 1.47-2.47), and absence of diagnosis of pre-obesity or obesity by the doctor (OR 5.61, 95% CI 4.51-7.00) to be associated with weight underestimation. Overestimation was significantly higher in women (19.6%) than in men (8.5%). Weight overestimation was negatively associated with male gender (OR 0.29, 95% CI 0.22-0.39), increasing age (p-value for trend <0.001), being born in Portugal (OR 0.37, 95% CI 0.16-0.87) and positively associated with absence of diagnosis (OR 3.11, 95% CI 2.23-4.34). Almost one quarter of the Swiss population aged 40 to 80 has weight misperception, underestimation being over twice as frequent as overestimation. Adequate diagnosis of overweight or obesity might be the best deterrent against weight misperception

Ipsilateral corticotectal projections from the primary, premotor and supplementary motor cortical areas in adult macaque monkeys: a quantitative anterograde tracing study

Ipsilateral corticotectal projections from the primary, premotor and supplementary motor cortical areas in adult macaque monkey

Real time ray tracing of skeletal implicit surfaces

Modeling and rendering in real time is usually done via rasterization of polygonal meshes. We present a method to model with skeletal implicit surfaces and an algorithm to ray trace these surfaces in real time in the GPU. Our skeletal representation of the surfaces allows to create smooth models easily that can be seamlessly animated and textured. The ray tracing is performed at interactive frame rate thanks to an acceleration data structure based on a BVH and a kd-tree