Guided Quasicontinuous Atom Laser

We report the first realization of a guided quasicontinuous atom laser by rf outcoupling a Bose-Einstein condensate from a hybrid optomagnetic trap into a horizontal atomic waveguide. This configuration allows us to cancel the acceleration due to gravity and keep the de Broglie wavelength constant at 0.5 $\mu$m during 0.1 s of propagation. We also show that our configuration, equivalent to pigtailing an optical fiber to a (photon) semiconductor laser, ensures an intrinsically good transverse mode matching.Comment: version published in Phys. Rev. Lett. 97, 200402 (2006

Dynamics of aggregate size and shape properties under sequenced flocculation in a turbulent Taylor-Couette reactor

This paper concerns experimental investigation of the sequenced flocculation of latex particles in a Taylor-Couette reactor. The aim of this work was to investigate the evolution of both the size and the shape of aggregates under sequenced hydrodynamics. A number of studies have focused on the evolution of the aggregate size or size distribution during steps of growth-breakage-regrowth, but aggregates generally experience steps of breakage-regrowth on repeated occasions in real operating conditions (passages near the impeller or during the transfer processes, for example). The experiments conducted in this work consisted thus of an alternation of six steps with alternately low and high shear rates under turbulent conditions. The particle size distributions were monitored throughout the sequencing, and the circularity and convexity (shape parameters) distributions were measured, enabling a more precise description of the entire floc population, rather than a fractal dimension. While the aggregate size distribution was clearly controlled by hydrodynamics, the shape distributions continuously evolved during the sequencing. The main new finding of our work notes the independence between the aggregate shape and hydrodynamics. Indeed, after multiples steps of breakage-regrowth, regardless of the aggregate size distribution and hydrodynamics, the aggregate shape seemed to reach a unique steady-state morphological distribution

Quasicontinuous horizontally guided atom laser: coupling spectrum and flux limits

We study in detail the flux properties of a radiofrequency outcoupled horizontally guided atom laser, following the scheme demonstrated in [Guerin W et al. 2006 Phys. Rev. Lett. 97 200402]. Both the outcoupling spectrum (flux of the atom laser versus rf frequency of the outcoupler) and the flux limitations imposed to operate in the quasicontinuous regime are investigated. These aspects are studied using a quasi-1D model, whose predictions are shown to be in fair agreement with the experimental observations. This work allows us to identify the operating range of the guided atom laser and to confirm its good promises in view of studying quantum transport phenomena

Fractal dimensions and morphological characteristics of aggregates formed in different physico-chemical and mechanical flocculation environments

Flocculation experiments were performed in a Taylor-Couette reactor in turbulent conditions characterized by the mean shear rate. A sequenced hydrodynamic protocol was applied which consists in low and high shear rates steps allowing to promote respectively aggregation and breakage processes. The particle size distribution and the 3D fractal dimension were determined on line by laser diffraction while morphological parameters were characterized off line using an automated microscope coupled with image processing. After a first aggregation-breakage cycle, the flocs formed by charge neutralization have smaller sizes than during the first aggregation step when the main aggregation mechanism is the charge neutralization whereas coarser but more resistant aggregates can be produced by bridging mechanism. During the flocculation process, high shear rates calibrate the flocs, creating small flocs having a size close to the Kolmogorov microscale. These small flocs serve as bricks to form larger flocs when lower shear rates are applied and a full reproducibility is observed after one or two cycles of the sequence depending on the aggregation mechanism. A clear correspondence was put in evidence between the shear rate conditions and the volume base mean size or fractal dimension of flocs. The morphological fractal dimension, as well as the fractal dimension derived from laser measurements, are in good agreement with the mean trend of the morphological data but cannot represent the whole diversity of floc sizes and shapes. The 3D surface base area and perimeter distributions appear as a promising tool allowing a deeper analysis of the impact of physico-chemical and shear conditions on aggregate properties during a flocculation proces

Cardiac and arterial interactions in end-stage renal disease

Cardiac and arterial interactions in end-stage renal disease. Although cardiac hypertrophy is a frequent complication of end-stage renal disease (ESRD), relatively little is known about large arterial geometry and function in vivo in these patients, and the relationship between arterial changes and cardiac hypertrophy is unknown. Common carotid artery (CCA) intima-media thickness and internal diameter and left ventricular geometry and function were determined by ultrasound imaging in 70 uncomplicated ESRD patients and in 50 age-, sex-, and blood pressure-matched controls. Arterial distensibility and compliance were determined from simultaneously recorded CCA diameter and stroke changes in diameter and CCA pressure waveforms, obtained by applanation tonometry, and also by the measurement of carotid-femoral pulse wave velocity. Compared with control subjects, ESRD patients had greater left ventricular diameter (P < 0.01), wall thicknesses and mass (P < 0.001), increased CCA diameter (6.25 ± 0.87 vs. 5.55 ± 0.65 mm; P < 0.001), larger CCA intima-media thickness (777 ± 115 vs. 678 ± 105 µ m; P < 0.001) and intima-media cross-sectional area (17.5 ± 4.5 vs. 13.4 ± 3.3mm2; P < 0.001). In uremic patients, arterial hypertrophy was associated with decreased CCA distensibility (17.8 ± 8.8 vs. 24.0 ± 12.7kPa−1 · 10−3; P < 0.001) and compliance (5.15 ± 2 vs. 6.0 ± 2.5m2 · kPa−1 · 10−7; P < 0.05), accelerated carotid-femoral pulse wave velocity (1055 ± 290 vs. 957 ± 180 cm/seconds; P < 0.001), early return and increased effect of arterial wave reflections (20.5 ± 15.4 vs. 9.2 ± 18.4%; P < 0.001). The latter phenomenons were responsible for increased pulsatile pressure load in CCA (58.3 ± 21 vs. 48 ± 17mm Hg; P < 0.01) and were associated with a decreased subendocardial viability index (157 ± 31 vs. 173 ± 30%; P < 0.001). The CCA diameter was correlated with the left ventricular diameter (P < 0.01), and a significant correlations existed between CCA wall thickness or CCA intima-media cross-sectional area and left ventricular wall thicknesses and/or left ventricular mass (P < 0.01). In multivariate analysis, these relationships were independent regarding age, sex, blood pressure and body surface area. The present study documents parallel cardiac and vascular adaptation in ESRD, and demonstrates the potential contribution of structural and functional large artery alterations to the pathogenesis of left ventricular hypertrophy and functional alterations

Monitoring elderly activities at home

International audienceThe elderly population is expected to grow dramatically over the next 20 years. As people grow older, they need more healthcare assistance. Without receiving sufficient care, elderly are at risk of loosing their autonomy. Thus a system permitting elderly to live safely at home is more than needed. Medical professionals believe that one of the best ways to detect emerging physical and mental health problems (before it becomes critical – particularly for the elderly) is to look for changes in their activities of daily living (ADLs). For this purpose, we propose a monitoring system which aims at detecting activities of daily living (ADLs) at home

A Computer system to monitor older adults at home: Preliminary results

International audienceDetermining the individual transition from the 3rd to the 4th of frailty phase of life is important for both the safety of the older person and to support the care provider. We developed an automatic monitoring system consisting of cameras and different sensors that analyze human behaviors and looks for changes in their activities by detecting the presence of people, their movements, and automatically recognizing events and Activities of Daily Living (ADLs). Assessment took place in a laboratory environment (GERHOME) comprised of four rooms (kitchen, living-room, bedroom, and bathroom). Data from 2 volunteers (64 and 85 years old) were analyzed. Precision in recognizing postures and events ranged from 62-94%, while sensitivity fell in the range of 62-87%. The system could differentiate ADL levels for the 64 and 85 year old subjects. These results are promising and merit replication and extension. Considerable work remains before the complete transition from 3rd to 4th life phase can be reliably detected. The GERHOME system is promising in this respect

Research in Complex Humanitarian Emergencies: The Médecins Sans Frontières/epicentre Experience

Vincent Brown and colleagues review Epicentre's 20 years of experience conducting research during complex humanitarian emergencies

Estimating Attributable Mortality Due to Nosocomial Infections Acquired in Intensive Care Units

Background. The strength of the association between intensive care unit (ICU)-acquired nosocomial infections (NIs) and mortality might differ according to the methodological approach taken. Objective. TO assess the association between ICU-acquired NIs and mortality using the concept of population-attributable fraction (PAF) for patient deaths caused by ICU-acquired NIs in a large cohort of critically ill patients. Setting. Eleven ICUs of a French university hospital. Design. We analyzed surveillance data on ICU-acquired NIs collected prospectively during the period from 1995 through 2003. The primary outcome was mortality from ICU-acquired NI stratified by site of infection. A matched-pair, case-control study was performed. Each patient who died before ICU discharge was defined as a case patient, and each patient who survived to ICU discharge was denned as a control patient. The PAF was calculated after adjustment for confounders by use of conditional logistic regression analysis. Results. Among 8,068 ICU patients, a total of 1,725 deceased patients were successfully matched with 1,725 control Patients. The adjusted PAF due to ICU-acquired NI for patients who died before ICU discharge was 14.6% (95% confidence interval [CI], 14.4%—14.8%). Stratified by the type of infection, the PAF was 6.1% (95% CI, 5.7%-6.5%) for pulmonary infection, 3.2% (95% CI, 2.8%-3.5%) for central venous catheter infection, 1.7% (95% CI, 0.9%-2.5%) for bloodstream infection, and 0.0% (95% CI, -0.4% to 0.4%) for urinary tract infection. Conclusions. ICU-acquired NI had an important effect on mortality. However, the statistical association between ICU-acquired NI and mortality tended to be less pronounced in findings based on the PAF than in study findings based on estimates of relative risk. Therefore, the choice of methods does matter when the burden of NI needs to be assesse

In vitro and in vivo antileishmanial efficacy of a combination therapy of diminazene and artesunate against Leishmania donovani in BALB /c mice

The in vitro and in vivo activity of diminazene (Dim), artesunate (Art) and combination of Dim and Art (Dim-Art) against Leishmania donovani was compared to reference drug; amphotericin B. IC50 of Dim-Art was found to be $2.28 \pm 0.24 \mu$ g/mL while those of Dim and Art were $9.16 \pm 0.3 \mu$ g/mL and $4.64 \pm 0.48 \mu$ g/mL respectively. The IC50 for Amphot B was $0.16 \pm 0.32 \mu$ g/mL against stationary-phase promastigotes. In vivo evaluation in the L. donovani BALB/c mice model indicated that treatments with the combined drug therapy at doses of 12.5 mg/kg for 28 consecutive days significantly ($p < 0.001$) reduced parasite burden in the spleen as compared to the single drug treatments given at the same dosages. Although parasite burden was slightly lower ($p < 0.05$) in the Amphot B group than in the Dim-Art treatment group, the present study demonstrates the positive advantage and the potential use of the combined therapy of Dim-Art over the constituent drugs, Dim or Art when used alone. Further evaluation is recommended to determine the most efficacious combination ratio of the two compounds.Comment: 4 Pages, 3 Figure