Potassium ion influx and Na+,K+-ATPase activity are required for the hamster sperm acrosome reaction.

The role of a K+ ion influx and Na+,K+-ATPase activity in the hamster sperm acrosome reaction (AR) was examined, using a range of concentrations of K+,K+ ionophores and a Na+,K+-ATPase inhibitor. Washed epididymal hamster sperm, capacitated in vitro in an artificial medium containing 2 mM Ca2+, 147 mM Na+, and 3, 6, 12, 18, or 24 mM K+, began undergoing the AR after 3 h of incubation. Sperm incubated in low K+ (0.9 mM) failed to undergo the AR even after 5 h of incubation. Sperm in 0.9 mM K+ could be induced to undergo the AR when either K+ (12 mM) alone or K+ (12 mM) with 0.1 microM nigericin was added after 3.5 h of incubation. The addition of K+ alone stimulated the AR in 30 min, whereas nigericin plus K+ stimulated the AR 15 min after addition. Neither nigericin added alone (0.9 mM K+) nor nigericin plus 12 mM K+ added to a low Ca2+ (0.35 mM) system resulted in acrosome reactions. Valinomycin (1 nM) did not stimulate the AR when added together with K+ (3-24 mM) to sperm incubated in 0.9 mM K+ for 3.5 h but markedly decreased sperm motility. Micromolar levels of ouabain blocked the AR when added between t = 0--3 h to sperm incubated with 3-24 mM K+. Inhibition of AR by the addition of 1 microM ouabain to sperm incubated with 3 mM K+ was completely reversed by the addition of 0.1 microM nigericin at t = 3.5 h. These results suggest that Na+,K+-ATPase activity and the resulting K+ influx are important for the mammalian sperm AR. Some similarities between requirements for the hamster sperm AR and secretory granule exocytosis are discussed

PRACTICAL DESIGN OF MINIMAL ENERGY CONTROLS FOR AN ELECTRIC BICYCLE

International audiencePRACTICAL DESIGN OF MINIMAL ENERGY CONTROLS FOR AN ELECTRIC BICYCL

Le Trésor artistique de la France

Le Trésor artistique de la France est un livre illustré de photographies, destiné à vulgariser le patrimoine artistique et édité par la Société anonyme des publications périodiques. Préparée à partir de 1876, sa publication, entamée en 1878, s’arrête dès la première série, dévolue aux œuvres de la galerie d’Apollon. L’analyse des exemplaires disponibles nous permet de relativiser le programme énoncé dans la préface. Comparé avec des objets similaires, réintégré dans les enjeux culturels, techniques et économiques de l’époque, l’ouvrage supporte en fait une fonction de promotion d’un nouveau procédé photographique, qui prime sur la vulgarisation des œuvres. Ainsi, le Trésor apparaît comme le cas d’espèce d’un type de livres que nous proposons de rassembler sous le terme de « livre-spécimen ». Son inachèvement devient alors moins le signe d’un échec que celui des changements qui s’opèrent dans les rapports qu’entretiennent le livre et la photo­graphie au tournant des années 1880.Le Trésor Artistique de la France (Treasury of French Art) is a book illustrated by photographs intended to popularize the French artistic heritage and published by the Société Anonyme des Publications Périodiques (Corporation for Periodical Publications). Planning began in 1876 and publishing began in 1878, and it ceased publication after its initial series, devoted to the works of the Galerie d’Apollon. My analysis of the available copies casts doubt on its intent as declared in its preface. Compared to similar works and considered in the context of the cultural, technological, and economic issues of the day, the evidence points to the work’s actual mission as the promotion of a new photographic process, an objective that takes precedence over the popularization of artworks. The Trésor emerges as a representative example of a type of book I propose to call the ‘livre-spécimen,’ or ‘specimen book.’ That it was never completed becomes less a sign of failure than of the changes taking place in the relations between books and photographs at the turn of the 1880s

Set inversion for χ-algorithms with application to guaranteed robot localization

International audienceCharacterizing the set of all parameter vectors such that their image by a vector function belongs to a given set is a set-inversion problem. The algorithm SIVIA (Set Inversion Via Interval Analysis) makes it possible to perform this task in an approximate but guaranteed way. In the examples treated so far, the function to be inverted was given either explicitly or by a sequential algorithm. In this paper, this approach is extended to the case of branching algorithms involving if statements. As an illustration, the static localization of a robot from bounded-error range measurements is considered. The notion of remoteness, introduced for an archetypal but realistic sonar model, allows this problem to be cast into the set-inversion framework

Progesterone Triggers a Wave of Increased Free Calcium during the Human Sperm Acrosome Reaction

AbstractThe mammalian sperm acrosome reaction (AR), an essential fertilization event, requires an influx of Ca2+. The Ca2+increase occurring in the human sperm head during the AR initiated by progesterone, a putativein vivoAR initiator, was investigated using video-image analysis with fura-2, a fluorescent Ca2+probe. Progesterone treatment of capacitated human sperm resulted in a wave-like increase in sperm head cytosolic [Ca2+]ithat appears to increase fastest in a region near the equatorial segment and then spreads throughout the rest of the head. The progesterone-mediated Ca2+increase in the sperm head was strongly inhibited and the wave eliminated by picrotoxin, a blocker of GABAAreceptor/Cl−channels and an inhibitor of the progesterone-mediated Cl−efflux and progesterone-initiated AR of human sperm. These results are the first to detect a ligand-mediated Ca2+wave in sperm and to suggest that Cl−efflux influences Ca2+influx during the AR

Robust autonomous robot localization using interval analysis

International audienceThis paper deals with the determination of the position and orientation of a mobile robot from distance measurements provided by a belt of onboard ultrasonic sensors. The environment is assumed to be two-dimensional, and a map of its landmarks is available to the robot. In this context, classical localization methods have three main limitations. First, each data point provided by a sensor must be associated with a given landmark. This data-association step turns out to be extremely complex and time-consuming, and its results can usually not be guaranteed. The second limitation is that these methods are based on linearization, which makes them inherently local. The third limitation is their lack of robustness to outliers due, e.g., to sensor malfunctions or outdated maps. By contrast, the method proposed here, based on interval analysis, bypasses the data-association step, handless the problem as nonlinera and in a global way and is (extraordinarily) robust to outliers

Guaranteed robust nonlinear estimation with application to robot localization

International audiencewhen rliable prior bounds on the acceptable erors between the data and corresponding model outputs are availabl, bounded-error estimation techniques make it possible to characterize the set of all acceptable parameter vectors in a guaranteed way, ven when the model is nonlinear and the number of data points small. However, when the data may contain outliers, i.e., data points for which these bounds should be violated, this set may turn out to be empty, or a least unrealistically small. The outlier minimal number estimator (OMNE) has been designed to deal with such a situation, by minimizing the number of data points considered as outliers. OMNE has been shown in previous papers to be remarkbly robust, even to a majority of outliers. Up to now, it was implemented by random scanning, so its results could not be guaranteed. In this paper, a new algorithm based on set inversion via interval analysis provides a guaranteed OMNE, which is applied to the initial localization of an actual robot in a partially known 2D environment. The difficult problems of associating range data to landmarks of the environment and of detecting potential outliers are solved as by-products of the procedure

Cédric Lesec (dir.), Zodiaque. Le monument livre

Publié en novembre 2012, Zodiaque. Le monument livre fait preuve d’une démarche originale dans le champ des études sur l’histoire du livre illustré de photographies. Dirigé par Cédric Lesec, il rassemble en effet les contributions de spécialistes de diverses branches de l’histoire de l’art autour d’un objet très circonscrit : les éditions Zodiaque. Créées par les moines bénédictins de l’atelier du Cœur-Meurtry, ces éditions ont activement participé à la diffusion de l’art roman européen à pa..

Chemical Differentiation of Human Osseous, Non-human Osseous, and Non-osseous Materials Using Scanning Electron Microscopy - Energy Dispersive X-ray Spectrometry (SEM/EDX) and Multivariate Statistical Analysis

Identification of osseous materials is generally established on gross anatomical factors; however, highly fragmented or taphonomically altered materials are often problematic and alternative methods, such as biological, histological, or chemical analysis, must be utilized. Recently, chemical methods have been proposed to sort unknown materials according to their Ca/P ratios. Ubelaker and colleagues (2002) proposed using SEM/EDX to achieve this distinction and Christensen and colleagues (2012) have validated X-ray Fluorescence Spectrometry (XRF) for this application. An alternative method of analysis involves performing principal component analysis (PCA) on element spectra to classify unknown materials based on their trace element composition. Zimmerman (2013) proposed the validity of this method with data obtained using hand held XRF. Subsequently, performing PCA on elemental data obtained using SEM/EDX demonstrates potential for material differentiation. Elemental weight percent data were collected using SEM/EDX then processed in R, version 3.0.1, by the R Foundation for Statistical Computing using PCA and Fisher Linear Discriminant Analysis. A two-tiered analysis was undertaken to improve discrimination between sample groups. The first tier involved distinguishing between osseous and non-osseous materials. After outliers were removed overall correct classification was 98.02% with one of 1504 osseous and 39 of 520 non-osseous spectra misclassifying. Since forty spectra were collected for each sample, the single misclassifying spectra would not affect the overall classification of the sample, resulting in 100% correct classification with a 0% error rate for the osseous samples. The second tier assessed differentiation of human and non-human osseous materials but demonstrated a poor correct classification rate of 72.41%. Finally, a blind study was conducted using 20 samples to assess the applicability for using this method to classify unknown materials as osseous or non-osseous. All of the samples were correctly classified resulting in 100% correct classification, further demonstrating the efficiency of SEM/EDX and statistical analysis for differentiation of osseous and non-osseous materials. Due to its high specificity, small sample requirements, and relative non-destructive testing protocol, as well as its presence in most modern crime laboratories, SEM/EDX has been proposed as a laboratory method for chemical differentiation of osseous and non-osseous materials. Additionally, the proposed method does not require advanced training or knowledge of analytical chemistry as the SEM/EDX provides clear results that can be processed using publically available statistical analysis software. By assessing and improving chemical analysis methodologies used for material differentiation, forensic anthropologists might be able to identify osseous and non-osseous samples as a preemptive step in forensic investigations involving fragmentary and taphonomically modified materials, reducing time and cost investments spent on forensically insignificant samples

Link travel time estimation in urban areas by detectors and probe vehicles fusion

International audienceThis paper presents an approach to estimate link travel time in urban areas. This approach consists of a data fusion from underground loop detectors and probe vehicles equipped with global positioning system (GPS). This method is expected to be more accurate, reliable and robust than using either of these data sources alone. In this approach, an algorithm is developed. This algorithm is based on the unscented Kalman filter using vehicle counts and flows from loop detectors located at the end of every link, and travel time from probe vehicles. From these counts the average travel time is calculated using the "cumulative plot" method. Furthermore, in order to incorporate the GPS data, a map-matching method is used to associate a travel time to the appropriate link