Les Lapita : nomades du Pacifique

International audienceQui étaient les Lapita, ce peuple qui, il y a plus de 3 000 ans, a colonisé nombre des îles du Pacifique, pour certaines alors inconnues ? Qui étaient ces hommes, comment ont-ils navigué et peuplé ces îles vierges ? Qui étaient ces hommes, comment ont-ils navigué et peuplé ? Par quelles voies maritimes sont-ils venus depuis l’Asie du Sud-Est ? Les Lapita sont-ils les ancêtres de tous les Océaniens actuels ? Qui étaient ces hommes, comment ont-ils navigué et peuple ? Que signifient les fameux motifs qui caractérisent leurs poteries et qui dessinent le fil rouge permettant de retracer leur épopée ? Un mouvement de peuplement stupéfiant par son ampleur géographique, près de 4 500 kilomètres parcourus d’ouest en est, et par sa courte durée, moins de 700 ans.Premier travail de synthèse en français consacré aux Lapita, cet ouvrage dépeint cette grande aventure maritime et fait le point sur les plus récentes découvertes de l’archéologie. Les sites, les motifs céramiques et les différentes hypothèses sur l’histoire des Lapita sont présentés de manière simple et didactique. Les nouvelles interprétations des décors des poteries permettent d’éclairer la période sous un jour nouveau. Les études de linguistique historique et d’ethnologie, mais aussi les nouvelles méthodes de biogénétique viennent en complément de l’archéologie pour mettre en lumière la vie sociale et culturelle des Lapita : la parenté, l’organisation sociale, l’environnement naturel, la navigation et même les croyances sont autant de domaines permettant de proposer une esquisse de ces ancêtres des peuples océaniens. Rendant compte de tous les aspects de la recherche actuelle sous une forme claire et accessible, cet ouvrage s’adresse autant aux spécialistes qu’aux étudiants et aux amateurs intéressés par cette période cruciale de la préhistoire océanienne

Ultrasensitive Displacement Noise Measurement of Carbon Nanotube Mechanical Resonators

Mechanical resonators based on a single carbon nanotube are exceptional sensors of mass and force. The force sensitivity in these ultra-light resonators is often limited by the noise in the detection of the vibrations. Here, we report on an ultra-sensitive scheme based on a RLC resonator and a low-temperature amplifier to detect nanotube vibrations. We also show a new fabrication process of electromechanical nanotube resonators to reduce the separation between the suspended nanotube and the gate electrode down to $\sim 150$~nm. These advances in detection and fabrication allow us to reach $0.5~\mathrm{pm}/\sqrt{\mathrm{Hz}}$ displacement sensitivity. Thermal vibrations cooled cryogenically at 300~mK are detected with a signal-to-noise ratio as high as 17~dB. We demonstrate $4.3~\mathrm{zN}/\sqrt{\mathrm{Hz}}$ force sensitivity, which is the best force sensitivity achieved thus far with a mechanical resonator. Our work is an important step towards imaging individual nuclear spins and studying the coupling between mechanical vibrations and electrons in different quantum electron transport regimes.Comment: 9 pages, 5 figure

Variability and short-term determinants of walking capacity in patients with intermittent claudication

OBJECTIVE: Global positioning system (GPS) recordings can provide valid information on walking capacity in patients with peripheral arterial disease (PAD) and intermittent claudication (IC) during community-based outdoor walking. This study used GPS to determine the variability of the free-living walking distance between two stops (WDBS), induced by lower-limb pain, which may exist within a single stroll in PAD patients with IC and the potential associated parameters obtained from GPS analysis.METHODS: This cross-sectional study of 57 PAD patients with IC was conducted in a university hospital. The intervention was a 1-hour free-living walking in a flat public park with GPS recording at 0.5 Hz. GPS-computed parameters for each patient were WDBS, previous stop duration (PSD), cumulated time from the beginning of the stroll, and average walking speed for each walking bout. The coefficient of variation of each parameter was calculated for patients with the number of walking bouts (N(WB)) >or=5 during their stroll. A multivariate analysis was performed to correlate WDBS with the other parameters. RESULTS: Mean (SD) maximal individual WDBS was 1905 (1189) vs 550 (621) meters for patients with N(WB) <5 vs N(WB) >or= 5, respectively (P < .001). In the 36 patients with N(WB) >or= 5, the coefficient of variation for individual WDBS was 43%. Only PSD and cumulated time were statistically associated with WDBS in 16 and 5 patients, respectively. CONCLUSIONS: A wide short-term variability of WDBS exists and likely contributes to the difficulties experienced by patients with IC to estimate their maximal walking distance at leisurely pace. Incomplete recovery from a preceding walk, as estimated through PSD, seems to dominantly account for the WDBS in patients with IC

Simulator-based assessment of ankle arterial systolic blood pressure measurement skills

OBJECTIVE: Learning basic vascular examination is a complex process. Very few studies have focused on the ability to measure the arterial systolic blood pressure at the ankle (ASBPa). The aim of this study was to objectively assess the effects of a 1-h practical educational intervention on the ability to measure ASBPa among medical students. METHODS: A total of 27 medical students were prospectively recruited. Two evaluation sessions of ASBPa measurement skills were conducted, before (T1) and after a 1-h practical lesson (T2). To assess the learning effect associated to the simulator-based evaluation, a control group composed by nonmedical students, not involved in the practical lesson, was also tested. Objective assessments of ASBPa measurements were performed by an instrumented leg prototype. RESULTS: There was a nonsignificant decreasing trend measurement time after practical lesson. The average pressure determination error (ΔP) was significantly reduced: ΔPT1: 10.5 ± 13.8 mmHg vs. ΔPT2: 5.7 ± 6.0 mmHg (P = 0.002). The mean deflation rate (DR) of the cuff was significantly decreased: DRT1: 12.9 ± 9.2 mmHg/s vs. DRT2: 8.7 ± 4.6 mmHg/s (P = 0.001). The control group did not show significant changes. CONCLUSION: A 1-h practical learning could improve some parameters of the ASBPa measurement among medical students, but was not sufficient to allow the measured technical factors to reach established guidelines

The Barriers of the Assistive Robotics Market—What Inhibits Health Innovation?

Demographic changes are putting the healthcare industry under pressure. However, while other industries have been able to automate their operation through robotic and autonomous systems, the healthcare sector is still reluctant to change. What makes robotic innovation in healthcare so difficult? Despite offering more efficient, and consumer-friendly care, the assistive robotics market has lacked penetration. To answer this question, we have broken down the development process, taking a market transformation perspective. By interviewing assistive robotics companies at different business stages from France and the UK, this paper identifies new insight into the main barriers of the assistive robotics market that are inhibiting the sector. Their impact is analysed during the different stages of the development, exploring how these barriers affect the planning, conceptualisation and adoption of these solutions. This research presents a foundation for understanding innovation barriers that high-tech ventures face in the healthcare industry, and the need for public policy measures to support these technology-based firms.</jats:p

Scandal - A Facility For Elastic Neutron Scattering Studies in the 50-130 MeV Range

A facility for detection of scattered neutrons in the energy interval 50−130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), is part of the standard detection system at the 20-180 MeV neutron beam facility of the The Svedberg Laboratory, Uppsala. It has primarily been used for studies of elastic neutron scattering, but it has been employed for (n,p) and (n,d) reaction experiments as well. Results of recent experiments are presented to illustrate the performance of the spectrometer. Recently, the facility has been upgraded to perform also (n,Xn') experiments. For this purpose, a new converter, CLODIA, has been developed and installed. Preliminary results of the commissioning of CLODIA will be presented