North western Alps Holocene paleohydrology recorded by flooding activity in Lake Le Bourget, France and possible relations with Mont-Blanc glaciers fluctuations

International audienceA 14-m long piston core was retrieved from Lake Le Bourget, NWAlps (France), in order to provide a continuous record of flooding events of the Rhone River during the Holocene. The selection of the coring site was based on high resolution seismic profiling, in an area with limited mass wasting deposits and accumulated proximal Rhone River inter-and underflow deposits. The age-depth model of this core is based on (i) 14 AMS radiocarbon dates, (ii)radionuclide dating(137Cs) and (iii) the identification of historical data (flood events, eutrophication of the lake).The sedimentary record dates back to 9400 cal BP, and includes a thin mass wasting event deposited around 4500 cal BP. A multi-proxy approach was used to track the evolution and origin of clastic sedimentation during the Holocene, in order to identify periods of higher hydrologic al activity in the catchment area. Spectrophotometry was used to detect fluctuations in clastic supply and the study of clay minerals (especially the Illite crystallinity index) allowed locating the main source area of fine grained clastic particles settling at the lake after flood events. This dataset highlights up to 12 periods of more intense flooding events over the last 9400 years in Lake Le Bourget and shows that the main source area of clastic particles during this period is the upper part of the Arve River drainage basin. This part of the catchment area drains several large glaciers from the Mont-Blanc Massif, and fluctuations in Rhone River flood supply in Lake Le Bourget is interpreted as resulting essentially from Mont-Blanc Glacier activity during the Holocene.The comparison of clastic sedimentationin Lake Le Bourget with periods of increasing land use and periods of Alpine glacier and mid-European lake level fluctuations, suggest that the core LDB04 clastic record in Lake Le Bourget is a continuous proxy of the Holocene hydrologic al history of the NW Alps

Computational design of high performance hybrid perovskite on silicon tandem solar cells

In this study, the optoelectronic properties of a monolithically integrated series-connected tandem solar cell are simulated. Following the large success of hybrid organic-inorganic perovskites, which have recently demonstrated large efficiencies with low production costs, we examine the possibility of using the same perovskites as absorbers in a tandem solar cell. The cell consists in a methylammonium mixed bromide-iodide lead perovskite, CH3NH3PbI3(1-x)Br3x (0 < x < 1), top sub-cell and a single-crystalline silicon bottom sub-cell. A Si-based tunnel junction connects the two sub-cells. Numerical simulations are based on a one-dimensional numerical drift-diffusion model. It is shown that a top cell absorbing material with 20% of bromide and a thickness in the 300-400 nm range affords current matching with the silicon bottom cell. Good interconnection between single cells is ensured by standard n and p doping of the silicon at 5.10^19cm-3 in the tunnel junction. A maximum efficiency of 27% is predicted for the tandem cell, exceeding the efficiencies of stand-alone silicon (17.3%) and perovskite cells (17.9%) taken for our simulations, and more importantly, that of the record crystalline Si cells.Comment: 17 pages, 7 figure

Slowest relaxation mode of the partially asymmetric exclusion process with open boundaries

We analyze the Bethe ansatz equations describing the complete spectrum of the transition matrix of the partially asymmetric exclusion process on a finite lattice and with the most general open boundary conditions. We extend results obtained recently for totally asymmetric diffusion [J. de Gier and F.H.L. Essler, J. Stat. Mech. P12011 (2006)] to the case of partial symmetry. We determine the finite-size scaling of the spectral gap, which characterizes the approach to stationarity at large times, in the low and high density regimes and on the coexistence line. We observe boundary induced crossovers and discuss possible interpretations of our results in terms of effective domain wall theories.Comment: 30 pages, 9 figures, typeset for pdflatex; revised versio

Sarcopenia and cognitive impairment in elderly women: results from the EPIDOS cohort

BACKGROUND: common pathophysiological pathways are shared between age-related body composition changes and cognitive impairment. OBJECTIVE: evaluate whether current operative sarcopenia definitions are associated with cognition in community-dwelling older women. DESIGN: cross-sectional analyses. SUBJECTS: a total of 3,025 women aged 75 years and older. MEASUREMENTS: body composition (assessed by dual energy X-ray absorptiometry) and cognition (measured by short portable mental status questionnaire) were obtained in all participants. Multivariate logistic regression models assessed the association of six operative definitions of sarcopenia with cognitive impairment. Gait speed (GS, measured over a 6-meter track at usual pace) and handgrip strength (HG, measured by a hand-held dynamometer) were considered additional factors of interest. RESULTS: a total of 492 (16.3%) women were cognitively impaired. The prevalence of sarcopenia ranged from 3.3 to 18.8%. No sarcopenia definition was associated with cognitive impairment after controlling for potential confounders. To proof consistency, the analyses were performed using GS and HG, two well-established predictors of cognitive impairment. Low GS [odds ratio (OR) 2.42, 95% confidence interval (CI) 1.72-3.40] and low HG (OR: 1.81, 95% CI: 1.33-2.46) were associated with cognitive impairment. CONCLUSION: no significant association was evidenced between different operative sarcopenia definitions and cognitive impairment. The study suggests that the association between physical performance and cognitive impairment in not mediated by sarcopenia

Biological properties of water-soluble phosphorhydrazone dendrimers

1984-8250Dendrimers are hyperbranched and perfectly defined macromolecules, constituted of branches emanating from a central core in an iterative fashion. Phosphorhydrazone dendrimers constitute a special family of dendrimers, possessing one phosphorus atom at each branching point. The internal structure of these dendrimers is hydrophobic, but hydrophilic terminal groups can induce the solubility of the whole structure in water. Indeed, the properties of these compounds are mainly driven by the type of terminal groups their bear; this is especially true for the biological properties. For instance, positively charged terminal groups are efficient for transfection experiments, as drug carriers, as anti-prion agents, and as inhibitor of the aggregation of Alzheimer's peptides, whereas negatively charged dendrimers have anti-HIV properties and can influence the human immune system, leading to anti-inflammatory properties usable against rheumatoid arthritis. This review will give the most representative examples of the biological properties of water-soluble phosphorhydrazone dendrimers, organized depending on the type of terminal groups they bear

Global warming: is weight loss a solution?

The current climate change has been most likely caused by the increased greenhouse gas emissions. We have looked at the major greenhouse gas, carbon dioxide (CO2), and estimated the reduction in the CO2 emissions that would occur with the theoretical global weight loss. The calculations were based on our previous weight loss study, investigating the effects of a low-carbohydrate diet on body weight, body composition and resting metabolic rate of obese volunteers with type 2 diabetes. At 6 months we observed decreases in weight, fat mass, fat free mass and CO2 production. We estimated that a 10 kg weight loss of all obese and overweight people would result in a decrease of 49.560 Mt of CO2 per year, which would equal to 0.2 % of the CO2 emitted globally in 2007. This reduction could help meet the CO2 emission reduction targets and unquestionably would be of a great benefit to the global health

User-centered virtual environment design for virtual rehabilitation

<p>Abstract</p> <p>Background</p> <p>As physical and cognitive rehabilitation protocols utilizing virtual environments transition from single applications to comprehensive rehabilitation programs there is a need for a new design cycle methodology. Current human-computer interaction designs focus on usability without benchmarking technology within a user-in-the-loop design cycle. The field of virtual rehabilitation is unique in that determining the efficacy of this genre of computer-aided therapies requires prior knowledge of technology issues that may confound patient outcome measures. Benchmarking the technology (e.g., displays or data gloves) using healthy controls may provide a means of characterizing the "normal" performance range of the virtual rehabilitation system. This standard not only allows therapists to select appropriate technology for use with their patient populations, it also allows them to account for technology limitations when assessing treatment efficacy.</p> <p>Methods</p> <p>An overview of the proposed user-centered design cycle is given. Comparisons of two optical see-through head-worn displays provide an example of benchmarking techniques. Benchmarks were obtained using a novel vision test capable of measuring a user's stereoacuity while wearing different types of head-worn displays. Results from healthy participants who performed both virtual and real-world versions of the stereoacuity test are discussed with respect to virtual rehabilitation design.</p> <p>Results</p> <p>The user-centered design cycle argues for benchmarking to precede virtual environment construction, especially for therapeutic applications. Results from real-world testing illustrate the general limitations in stereoacuity attained when viewing content using a head-worn display. Further, the stereoacuity vision benchmark test highlights differences in user performance when utilizing a similar style of head-worn display. These results support the need for including benchmarks as a means of better understanding user outcomes, especially for patient populations.</p> <p>Conclusions</p> <p>The stereoacuity testing confirms that without benchmarking in the design cycle poor user performance could be misconstrued as resulting from the participant's injury state. Thus, a user-centered design cycle that includes benchmarking for the different sensory modalities is recommended for accurate interpretation of the efficacy of the virtual environment based rehabilitation programs.</p

A search for direct muon production in the forward direction

We propose to search for direct muon production in the forward direction from 300 GeV protons incident on a heavy nuclear target. By using the first stage of the Ml beam as a source of a diffracted proton beam and the second and third stages of Ml as a spectrometer, one can make a measurement of the direct muon to pion ratio at values of x between 0.3 and 0.75. If this ratio is on the order of 10{sup -4}, the event rates are on the order of 800 direct muons/hr. at an x of .5. The modifications to the Ml beam are minor

Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S

We report the discovery of very-high-energy (VHE) gamma-ray emission of the binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the H.E.S.S. experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a gamma-ray signal from the binary system was detected with a total significance above 13 sigma. The flux was found to vary significantly on timescales of days which makes PSR B1259-63 the first variable galactic source of VHE gamma-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law F_0(E/1 TeV)^-Gamma with a photon index Gamma = 2.7+-0.2_stat+-0.2_sys and flux normalisation F_0 = (1.3+-0.1_stat+-0.3_sys) 10^-12 TeV^-1 cm^-2 s^-1. This detection of VHE gamma-rays provides unambiguous evidence for particle acceleration to multi-TeV energies in the binary system. In combination with coeval observations of the X-ray synchrotron emission by the RXTE and INTEGRAL instruments, and assuming the VHE gamma-ray emission to be produced by the inverse Compton mechanism, the magnetic field strength can be directly estimated to be of the order of 1 G.Comment: 10 pages, 8 figures, accepted in Astronomy and Astrophysics on 2 June 2005, replace: document unchanged, replaced author field in astro-ph entry - authors are all members of the H.E.S.S. collaboration and three additional authors (99+3, see document

A cost-effectiveness analysis of provider and community interventions to improve the treatment of uncomplicated malaria in Nigeria: study protocol for a randomized controlled trial.

BACKGROUND: There is mounting evidence of poor adherence by health service personnel to clinical guidelines for malaria following a symptomatic diagnosis. In response to this, the World Health Organization (WHO) recommends that in all settings clinical suspicion of malaria should be confirmed by parasitological diagnosis using microscopy or Rapid Diagnostic Test (RDT). The Government of Nigeria plans to introduce RDTs in public health facilities over the coming year. In this context, we will evaluate the effectiveness and cost-effectiveness of two interventions designed to support the roll-out of RDTs and improve the rational use of ACTs. It is feared that without supporting interventions, non-adherence will remain a serious impediment to implementing malaria treatment guidelines. METHODS/DESIGN: A three-arm stratified cluster randomized trial is used to compare the effectiveness and cost-effectiveness of: (1) provider malaria training intervention versus expected standard practice in malaria diagnosis and treatment; (2) provider malaria training intervention plus school-based intervention versus expected standard practice; and (3) the combined provider plus school-based intervention versus provider intervention alone. RDTs will be introduced in all arms of the trial. The primary outcome is the proportion of patients attending facilities that report a fever or suspected malaria and receive treatment according to malaria guidelines. This will be measured by surveying patients (or caregivers) as they exit primary health centers, pharmacies, and patent medicine dealers. Cost-effectiveness will be presented in terms of the primary outcome and a range of secondary outcomes, including changes in provider and community knowledge. Costs will be estimated from both a societal and provider perspective using standard economic evaluation methodologies. TRIAL REGISTRATION: Clinicaltrials.gov NCT01350752