Natural Abstraction

Using nature as a model has provided a basis for architectural history that has oscillated between modeling itself on the example of nature and the opposite notion of modeling nature itself

Target Acquisition in Multiscale Electronic Worlds

Since the advent of graphical user interfaces, electronic information has grown exponentially, whereas the size of screen displays has stayed almost the same. Multiscale interfaces were designed to address this mismatch, allowing users to adjust the scale at which they interact with information objects. Although the technology has progressed quickly, the theory has lagged behind. Multiscale interfaces pose a stimulating theoretical challenge, reformulating the classic target-acquisition problem from the physical world into an infinitely rescalable electronic world. We address this challenge by extending Fitts’ original pointing paradigm: we introduce the scale variable, thus defining a multiscale pointing paradigm. This article reports on our theoretical and empirical results. We show that target-acquisition performance in a zooming interface must obey Fitts’ law, and more specifically, that target-acquisition time must be proportional to the index of difficulty. Moreover, we complement Fitts’ law by accounting for the effect of view size on pointing performance, showing that performance bandwidth is proportional to view size, up to a ceiling effect. The first empirical study shows that Fitts’ law does apply to a zoomable interface for indices of difficulty up to and beyond 30 bits, whereas classical Fitts’ law studies have been confined in the 2-10 bit range. The second study demonstrates a strong interaction between view size and task difficulty for multiscale pointing, and shows a surprisingly low ceiling. We conclude with implications of these findings for the design of multiscale user interfaces

High power switching transistor Final report

Design theory and fabrication procedure for n-p-n 100 ampere silicon switching transisto

Head Injuries in Professional Football (Soccer)

Introduction: Head injuries in sports may have been an underestimated health risk for many years. However, they potentially bear the risk of serious long-term sequelae with a potential impact on the athletes’ activities of daily living, sports, or career. Although the incidence of head injuries in professional football (soccer) is relatively low in comparison to so-called high-risk sports such as American football, rugby, boxing, or ice hockey, absolute numbers are substantial because of the high popularity of this sport and the large number of players. In 2006, a first step towards head injury prevention in football was made by altering a rule: henceforth intentional elbow to head contacts had to be punished by a red card. This action determined one of the three aims of this thesis: i) to present incidence rates of head injuries including their time trends and injury mechanisms; ii) to identify circumstances of head injury incidents, the behavior of referees, and their decisions; and iii) to investigate the effect of the rule change on the reduction of head injuries in professional male football. Methods: i) To investigate the time trends of head injuries, an analysis of head injuries in the 1st German Bundesliga was generated comprising the 11 consecutive seasons (2006/07 to 2016/17) following the rule change. The head injury database was based on continuously published data from the German football magazine “kicker Sportmagazin®” and other media sources. Injury mechanisms were analysed from video recordings. Injury incidence rates (IR) and 95% confidence intervals (95% CI) were calculated. Time trends were analysed via linear regression. ii) To identify circumstances of head injury incidents, the video analyses of all head injuries from 13 consecutive seasons (2000/01 to 2012/13) were screened. iii) To provide a description of injury mechanisms of head injuries and the effect of the rule change, the database of all head injuries comprising seasons 2000/01 to 2012/13 were screened and the equal number of seasons before and after the rule change were compared. Head injury mechanisms were analysed from video recordings. IRs and 95% CI as well as incidence rate ratios (IRR) to assess differences in injury rates six seasons before and six seasons after the rule change were calculated. Results: i) During the 11 consecutive seasons, 238 head injuries occurred during matches (IR 1.77 per 1000 match hours). There were no significant seasonal changes (expressed as annual average year-to-year change) in IRs over the 11-year period for total head injuries, facial and head fractures, head and face lacerations and abrasions, and head contusions. The average year-toyear increase for concussion was 6.4%. There were no seasonal changes in head injury mechanisms over the study period. ii) Most head injury incidents involved two players. Those players who suffered a subsequent head injury predominantly jumped (60%), headed the ball (36%), and ran forwards (20%), whereas the non-injured players mainly jumped (64%), headed the ball (27%), and raised the elbow to the head (23%). Free ball situations (two players challenging/dueling for the ball) caused the largest proportion of the head injuries (81%). iii) 356 head injuries were recorded (IR 2.22 per 1000 match hours) in 13 consecutive seasons. Contact with another player resulted in the greatest proportion of head injuries, especially head to head (34%) and elbow to head (17%) contacts. After the rule change the total number of head injuries was reduced by 29%. The subcategories head and face lacerations and abrasions declined by 42%, concussions by 29%, head contusions by 18% and facial and head fractures by 16%. Discussion/Conclusion: The first study in this thesis revealed that the subcategory concussion increased slightly over the (2006/07 to 2016/17) seasons, which could be the result of increasing match dynamics and/or a raised awareness for this injury type among team physicians and players. Total head injuries and the other subcategories remained reasonably stable over 11 consecutive seasons. The second study showed that heading duels are particularly associated with head injuries and could be target of future prevention strategies. The third study provided evidence that the incidence rates for total number of head injuries and their respective subcategories were lower in the six seasons after the rule change compared to the equal number of seasons before. Therefore, rule changes in football appear to be effective in reducing the occurrence of head injuries. To summarize, the increasing number of concussions requires action. Ongoing monitoring and surveying of head injuries allows practitioners to keep track of head injuries. For future research, the development of preventative measures to avoid potential (serious) health consequences of head injuries is warranted

Retour aux origines de la statistique textuelle : Benzécri et l'école française d'analyse des données

International audienceIn this article, we have attempted to trace the history of the statistical analysis of textual data, focusing on the influence of Benzécri's work and school, and to make explicit their theoretical positions, clearly opposed to AI and to Chomskyan linguistics. After a presentation of the intellectual project, as an inductive approach to language based on the exploration of corpora, we present the principles of correspondence analysis, which is the main method developed in the Data Analysis School, used for corpus analysis but also for many other types of datasets. Then, we will focus on textual data analysis. Based on the fact that software programmes have played a major role in the use of these statistical techniques, we shall examine a selection of these, display their specificities and their underlying theoretical bases.Résumé Cet article revient sur une des deux branches à l'origine de la statistique textuelle, l'école d'analyse des données « à la française », dont Jean-Paul Benzécri peut être considéré comme l'initiateur. Après avoir explicité les orientations théoriques de l'analyse des données, et le rôle joué par une approche inductive du langage, nous présentons rapidement les principes de l'analyse des correspondances. Ensuite, nous explorerons l'application de l'analyse des données aux corpus de textes en montrant le rôle joué par les logiciels dans la diffusion de cette approche

High frequency oscillations of first eigenmodes in axisymmetric shells as the thickness tends to zero

The lowest eigenmode of thin axisymmetric shells is investigated for two physical models (acoustics and elasticity) as the shell thickness (2$\epsilon$) tends to zero. Using a novel asymptotic expansion we determine the behavior of the eigenvalue $\lambda$($\epsilon$) and the eigenvector angular frequency k($\epsilon$) for shells with Dirichlet boundary conditions along the lateral boundary, and natural boundary conditions on the other parts. First, the scalar Laplace operator for acoustics is addressed, for which k($\epsilon$) is always zero. In contrast to it, for the Lam{\'e} system of linear elasticity several different types of shells are defined, characterized by their geometry, for which k($\epsilon$) tends to infinity as $\epsilon$ tends to zero. For two families of shells: cylinders and elliptical barrels we explicitly provide $\lambda$($\epsilon$) and k($\epsilon$) and demonstrate by numerical examples the different behavior as $\epsilon$ tends to zero

Free Vibrations of Axisymmetric Shells: Parabolic and Elliptic cases

Approximate eigenpairs (quasimodes) of axisymmetric thin elastic domains with laterally clamped boundary conditions (Lam{\'e} system) are determined by an asymptotic analysis as the thickness ($2\varepsilon$) tends to zero. The departing point is the Koiter shell model that we reduce by asymptotic analysis to a scalar modelthat depends on two parameters: the angular frequency $k$ and the half-thickness $\varepsilon$. Optimizing $k$ for each chosen $\varepsilon$, we find power laws for $k$ in function of $\varepsilon$ that provide the smallest eigenvalues of the scalar reductions.Corresponding eigenpairs generate quasimodes for the 3D Lam{\'e} system by means of several reconstruction operators, including boundary layer terms. Numerical experiments demonstrate that in many cases the constructed eigenpair corresponds to the first eigenpair of the Lam{\'e} system.Geometrical conditions are necessary to this approach: The Gaussian curvature has to be nonnegative and the azimuthal curvature has to dominate the meridian curvature in any point of the midsurface. In this case, the first eigenvector admits progressively larger oscillation in the angular variable as $\varepsilon$ tends to $0$. Its angular frequency exhibits a power law relationof the form $k=\gamma \varepsilon^{-\beta}$ with $\beta=\frac14$ in the parabolic case (cylinders and trimmed cones), and the various $\beta$s $\frac25$, $\frac37$, and $\frac13$ in the elliptic case.For these cases where the mathematical analysis is applicable, numerical examples that illustrate the theoretical results are presented

Comparison of species sensitivity distributions based on population or individual endpoints

International audienceSpecies sensitivity distributions (SSDs) developed from individual and population endpoints were compared based on simulations and a case study. The simulations were performed with five invertebrate species accounting for the diversity of benthic macroinvertebrate communities in large European lowland rivers and for five benthic invertebrates used as laboratory species. Population growth rate 10% effective concentration (EC10) values were, in most of the simulations, higher than the lowest of the EC10 values at the individual level. However, for the set of ecologically representative species, the fifth percentile level of this distribution (HC5) was more protective for population endpoints than for individual endpoints. This was the opposite for the set of laboratory species. Population and individual SSDs were also compared based on existing data on Cu for the five laboratory invertebrate species. In this case, the calculated population HC5 value was almost twice the individual value, and the authors showed much reduced variability between species sensitivities at population level compared with individual level. They conclude that population-based HC5 would generally be more protective than individual-based HC5. However, the change of level could reveal higher homogeneity at population level than at individual level, supporting the use of population-based HC5 to avoid overprotection. The authors thus advise the derivation of population-based HC5, as soon as it is possible, to derive such value with a relevant panel of species

Espace et échelle du mouvement : la loi de Fitts dans le monde physique et dans les mondes électroniques

Nous avons conçu et mis en oeuvre une approche nouvelle du paradigme classique du pointage faisant jouer un rôle central à la variable d’échelle. Nous utilisons le diagramme espace-échelle introduit par Furnas et Bederson (1995) dans le champ de l’interaction homme-machine (IHM). Fondé sur une géométrie inédite, ce type de représentation permet de visualiser les variations d’échelle en même temps que les déplacements dans l’espace, ce qui nous a permis d’analyser la cinématique de la navigation au sein des mondes électroniques multi-échelle (ou zoomables). Les travaux rapportés dans ce document se développent autour de la frontière qui sépare le monde réel et les mondes d’information. Le monde réel dans lequel s’inscrivent normalement nos mouvements est typiquement dynamique : il met en jeu la masse, la longueur et le temps. En revanche, les mondes d’information auxquels les humains sont exposés depuis à peine deux décennies sont d’essence purement cinématique, en ce sens qu’ils ignorent typiquement la masse, et donc les contraintes de force, d’énergie et de puissance. C’est la nature cinématique des mondes d’information qui explique que leurs contenus soient indéfiniment rescalables, propriété dont les objets du monde physique ne jouissent que dans une étroite mesure, comme on le sait depuis Galilée