L’altération des briquets en « marcassite » du « Trou de Chaleux » (Fouilles d'Édouard Dupont) : identification des phases minérales primaires et secondaires

Les nodules de sulfure de fer de la Grotte de Chaleux portent une encoche indiquant leur usage comme briquet. Leur minéralogie a été comparée avec d'autres nodules fibroradiés notamment ceux provenant du Cap Blanc Nez. La pyrite et non la marcassite a été identifiée par diffraction des rayons X. Le cœur de pyrite fibroradiée est entouré par une couronne de goethite probablement formée dans le contexte géologique. L'encoche anthropique est aussi tapissée de goethite attestant d'une oxydation de la pyrite dans le gisement archéologique. Non protégés des nouvelles conditions physico-chimiques prévalant dans les conservatoires, certains rognons se désagrègent à la suite de la cristallisation de sulfates de fer complexes déterminés par diffraction des rayons X, microscopie électronique à balayage et spectroscopie EDS. Les réactions chimiques qui prévalent s'auto-entretiennent entraînant la ruine du matériel. Les paragenèses changent dans le temps en fonction des variations des paramètres physico-chimiques. La préservation des artéfacts et des échantillons de pyrite ou de marcassite requiert d'empêcher le contact entre la phase sulfurée et l'air humide. Différentes méthodes existent mais aucune d’entre-elles n’est totalement fiable.Notches in the iron sulphide nodules of the Chaleux cave indicate their use as a lighter. Their mineralogy was compared with other fibroradiated nodules, more particularly coming from the Cap Blanc-Nez (France). Only pyrite rather than marcasite was identified by X-ray diffraction. Nodules are composed of a core of fibroradiated pyrite and an external rim of goethite, probably acquired in the geological environment. The human-made notch also exhibits a rim of goethite linked with the pyrite oxidation in the archaeological deposit. Under new physicochemical conditions prevailing in the conservatories, one of the exhumed nodules disintegrated as a result of the crystallization of complex secondary iron sulfates. The primary and secondary minerals from lighters and comparative material were determined by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Prevailing chemical reactions are self-sustaining causing the total destruction of the material. The paragenesis changes over time depending on changes in physicochemical parameters. Preservation of artifacts and samples of pyrite or marcasite demands to prevent contact between the sulphides and moist air. Different methods exist but none of them is completely reliable

Effect on bone turnover markers of once-yearly intravenous infusion of zoledronic acid versus daily oral risedronate in patients treated with glucocorticoids

Objective. Long-term glucocorticoid use is accompanied by rapid bone loss; however, early treatment with bisphosphonates prevents bone loss and reduces fracture risk. The aim of this study was to examine the effects of two bisphosphonates, i.v. zoledronic acid (ZOL) versus oral risedronate (RIS), on bone turnover markers (BTMs) in subjects with glucocorticoid-induced osteoporosis (GIO). Methods. Patients were randomly stratified according to the duration of pre-study glucocorticoid therapy [prevention subpopulation (ZOL, n = 144; RIS, n = 144) ≤3 months, treatment subpopulation (ZOL, n = 272; RIS, n = 273) >3 months]. Changes in β-C-terminal telopeptides of type 1 collagen (β-CTx), N-terminal telopeptide of type I collagen (NTx), procollagen type 1 N-terminal propeptide (P1NP) and bone-specific alkaline phosphatase (BSAP) from baseline were measured on day 10 and months 3, 6 and 12. Results. At most time points, there were significantly greater reductions (P < 0.05) in the concentrations of serum β-CTx, P1NP and BSAP and urine NTx in subjects on ZOL compared with RIS in both males and females of the treatment and prevention subpopulations. In pre- and post-menopausal women, there were significantly greater reductions in the concentrations of BTMs with ZOL compared with RIS. At 12 months, ZOL had significantly greater reductions compared with RIS (P < 0.05) for β-CTx, P1NP, BSAP and NTx levels, independent of glucocorticoid dose. Conclusions. Once-yearly i.v. infusion of ZOL 5 mg was well tolerated in different subgroups of GIO patients. ZOL was non-inferior to RIS and even superior to RIS in the response of BTMs in GIO patients. Trial registration: ClinicalTrials.gov, http://clinicaltrials.gov, NCT0010062

Analyse trajectcontrole

status: publishe

Modeling Acoustic Localization Accuracy for Scalable Energy Consumption in Wireless Sensor Swarms

Sensor swarms can be a cost-effectieve and more privacy-friendly alternative for location based service systems in building automation and health-care. To increase the battery lifetime of such swarm networks, the energy consumption should be scaled to the required localization accuracy. In this paper we described the first steps in developing an energy model that couples localization accuracy to energy-related sensor parameters such as sample frequency and ADC resolution. The goal is to use the model for the localization of undetermined environmental sounds, by means of wireless acoustic sensors. We show that for TDOA-based localization, the signal sample rate can be under the Nyquist frequency, provided that enough frequency components remain present in the undersampled signal. The resulting localization error is comparable with that of similar localization systems.status: publishe

Influence of Bluetooth Low Energy on WIFI communications and vice versa

In modern mobile devices such as smartphones and tablets, multiple wireless communication standards are supported. Since many of those standards operate at the licence free 2.4GHz ISM band, these standards use different modulation schemes and error correcting techniques in order to avoid interference when communicating over a wireless link (WIFI, Bluetooth, Bluetooth Low Energy...). For commercial use, these techniques are sufficient, but for industrial or medical use, in perhaps life threatening circumstances, all communications should perform at peak efficiency whilst not influencing each other. In this paper, a case study is presented where a healthcare setting is envisioned in which a WIFI network is deployed and used formedical purposes.We investigate the influence of a lot of transceiving Bluetooth Low Energy devices on theWIFI throughput, and vice versa. Conclusions and suggestions about the coexistance of both standards are also given.status: publishe

Indoor Room Location Estimation

This paper presents an indoor location estimation system, especially to locate people or objects at room level. First of all a theoretical approach is given. Secondly, a practical case, using our own system, is presented. Our system consists of a ZigBee-based wireless sensor network connected to a central PC. Using the signpost algorithm and considering the behavior of the received signal strength (RSS) through walls, floors and ceilings, we succeeded in developing a reliable indoor room localization system.status: publishe