Bone mineral: update on chemical composition and structure

Bone mineral: update on chemical composition and structur

A Laboratory Excitation Technique to Test Road Bike Vibration Transmission

This paper describes a technique designed to measure the in-situ acceleration signals that will be used to drive a road simulator in the study of road bike vibration transmission in a laboratory setting. To measure the signals, a bike mounted by a cyclist and towed by a motor vehicle is used. A road simulator using actuators driven by a digital signal is described. The impulse response of the bike used to measure road data is convoluted with the road acceleration in order to obtain the required actuator signal. The reproduction capacity of the simulator is evaluated by comparing the frequency content as well as the time statistical parameters of the acceleration signal measurement with road to the acceleration obtained on the simulator. On a granular road with a broadband excitation spectrum, the vertical excitation obtained with the simulator adequately mimics the measured road acceleration. This technique can be used to compare vibration transmission characteristics among different road bikes.The authors gratefully acknowledge financial support from the National Science and Engineering Council of Canada (NSERC) and the participation of Cervélo and Vroomen-White Design

High-frequency directivity effects: evidence from analysis of the Les Saintes records

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Modelling the contribution of short-range atmospheric and hydrological transfers to nitrogen fluxes, budgets and indirect emissions in rural landscapes

Spatial interactions within a landscape may lead to large inputs of reactive nitrogen (N<sub>r</sub>) transferred from cultivated areas and farms to oligotrophic ecosystems and induce environmental threats such as acidification, nitric pollution or eutrophication of protected areas. The paper presents a new methodology to estimate N<sub>r</sub> fluxes at the landscape scale by taking into account spatial interactions between landscape elements. This methodology includes estimates of indirect N<sub>r</sub> emissions due to short-range atmospheric and hydrological transfers. We used the NitroScape model which integrates processes of N<sub>r</sub> transformation and short-range transfer in a dynamic and spatially distributed way to simulate N<sub>r</sub> fluxes and budgets at the landscape scale. Four configurations of NitroScape were implemented by taking into account or not the atmospheric, hydrological or both pathways of N<sub>r</sub> transfer. We simulated N<sub>r</sub> fluxes, especially direct and indirect N<sub>r</sub> emissions, within a test landscape including pig farms, croplands and unmanaged ecosystems. Simulation results showed the ability of NitroScape to simulate patterns of N<sub>r</sub> emissions and recapture for each landscape element and the whole landscape. NitroScape made it possible to quantify the contribution of both atmospheric and hydrological transfers to N<sub>r</sub> fluxes, budgets and indirect N<sub>r</sub> emissions. For instance, indirect N<sub>2</sub>O emissions were estimated at around 21% of the total N<sub>2</sub>O emissions. They varied within the landscape according to land use, meteorological and soil conditions as well as topography. This first attempt proved that the NitroScape model is a useful tool to estimate the effect of spatial interactions on N<sub>r</sub> fluxes and budgets as well as indirect N<sub>r</sub> emissions within landscapes. Our approach needs to be further tested by applying NitroScape to several spatial arrangements of agro-ecosystems within the landscape and to real and larger landscapes

Application of the curvelet transform for pipe detection in GPR images

International audienceThis paper is dedicated to the detection of buried pipeswith a ground penetrating radar (GPR). The imagesfrom GPR acquisitions also called B-scan are corruptedby clutter and noise. In order to remove these undesirableitems we propose to use the properties of the curvelettransform. Were using this method as a first step of theautomatic detection of hyperbola in a B-scan

I021 Impact du polymorphisme génétique C(-260)T du CD14 sur la pression pulsée en fonction d’autres facteurs de risque cardiovasculaires : etude populationnelle transversale à partir du registre monica

Objectif de l’étudeLe CD14 est à l’intersection entre l’inflammation, les maladies infectieuses et le syndrome métabolique. Une corrélation positive entre la concentration plasmatique du CD14 soluble (sCD14) et la rigidité aortique a été décrite dans une étude transversale. Mais différents résultats ont été retrouvés sur l’incidence des évènements cardiovasculaires en fonction du polymorphisme C(-260)T du gène du CD14.L’objectif de cette étude est d’étudier l’influence du polymorphisme C(-260)T du CD14 sur la pression pulsée et indirectement sur le risque cardiovasculaire à partir de l’étude populationnelle transversale MONICA.Déroulement de l’étude1 155 sujets âgés entre 35 et 64 ans, en prévention primaire, ont été recrutés à partir des listes électorales de la Haute Garonne entre 1995 et 1997.MéthodesLa pression pulsée brachiale était mesurée au repos à 2 reprises puis moyennée. La concentration plasmatique du sCD14 a été mesurée par méthode immunoenzymatique. La randomisation est de type mendélienne. Les sujets ont été répartis en fonction du polymorphisme C(-260)T du CD14 après génotypage : homozygotes CC, homozygotes TT ou hétérozygotes CT.RésultatsLes sujets homozygotes TT ont une pression pulsée (PP) significativement plus basse et une concentration en sCD14 significativement plus élevée. Après ajustement avec les principaux facteurs confondants (âge, sexe, facteurs de risque cardiovasculaires traités), seul le génotype du CD14 reste corrélé à la PP. Cette corrélation n’intervient qu’en présence de facteurs de risque traités. Les diabétiques traités homozygotes TT sont ceux qui bénéficient de la plus importante baisse de PP par rapport aux homozygotes diabétiques CC (− 19,4mmHg, p=0,006).ConclusionCette étude suggère que les facteurs de risque ont un impact différent sur la pression pulsée en fonction du polymorphisme C(-260)T du CD14. Cette observation pourrait contribuer à affiner le risque cardiovasculaire absolu individuel, les sujets homozygotes TT ayant un risque cardiovasculaire moindre

Road bike comfort: on the measurement of vibrations induced to cyclist

With ride quality being one of the most sought-after characteristics of a road bicycle by customers as well as by bicycle manufacturers, the vibrational behaviour of the bicycle/cyclist system has grown into an active field in sport engineering research in recent years. When assessing bicycle transmissibility and ride comfort, it is important to control test conditions to obtain repeatable load and acceleration measurements at the cyclist’s contact points with the bicycle. Surprisingly, however, this consideration has not yet been specifically addressed in the literature. The aim of this paper is a first effort to investigate the effect of a selected set of test conditions on the measurement of vibration induced to the cyclist by a road bicycle. Our results showed that all the test conditions selected had a significant effect on the level of vibration induced to the cyclist.The authors gratefully acknowledge financial support from the National Science and Engineering Council of Canada (NSERC) and the participation of Cervélo and Vroomen-White Design

An inter-model assessment of the role of direct air capture in deep mitigation pathways

The feasibility of large-scale biological CO2 removal to achieve stringent climate targets remains unclear. Direct Air Carbon Capture and Storage (DACCS) offers an alternative negative emissions technology (NET) option. Here we conduct the first inter-model comparison on the role of DACCS in 1.5 and 2°C scenarios, under a variety of techno-economic assumptions. Deploying DACCS significantly reduces mitigation costs, and it complements rather than substitutes other NETs. The key factor limiting DACCS deployment is the rate at which it can be scaled up. Our scenarios’ average DACCS scale-up rates of 1.5 GtCO2/yr would require considerable sorbent production and up to 300 EJ/yr of energy input by 2100. The risk of assuming that DACCS can be deployed at scale, and finding it to be subsequently unavailable, leads to a global temperature overshoot of up to 0.8°C. DACCS should therefore be developed and deployed alongside, rather than instead of, other mitigation options

The relative contribution of road bicycle components on vibration induced to the cyclist

Improving comfort in road bicycle design is a paramount concern for cyclists, who are affected by the vibrations caused by constant contact with the road surface. The cycling community has deployed many efforts in the attempt to understand and improve bicycle comfort. However, these attempts have been focused on specific components such as the fork, frame and wheels without knowing their relative influence on vibration induced to the bicyclist (VIB). The objective of this paper is to assess the relative contribution of bicycle components on the VIB at the cyclist’s hands and buttocks. A factorial design test comparing the VIB in acceleration, force and power of different bicycle components has already shown that the handlebar and fork are the preponderant components for the VIB measured at the cyclist’s hands. At the buttocks, the preponderant components are the wheels and frame.The authors gratefully acknowledge financial support from the National Science and Engineering Council of Canada (NSERC) and the participation of Cervelo and Vroomen-White Design