Added value of bleach sedimentation microscopy for diagnosis of tuberculosis: a cost-effectiveness study.

SETTING: Bleach sedimentation is a method used to increase the diagnostic yield of sputum microscopy for countries with a high prevalence of human immunodeficiency virus (HIV) infection and limited resources. OBJECTIVES: To compare the relative cost-effectiveness of different microscopy approaches in diagnosing tuberculosis (TB) in Kenya. METHODS: An analytical decision tree model including cost and effectiveness measures of 10 combinations of direct (D) and overnight bleach (B) sedimentation microscopy was constructed. Data were drawn from the evaluation of the bleach sedimentation method on two specimens (first on the spot [1] and second morning [2]) from 644 TB suspects in a peripheral health clinic. Incremental cost per smear-positive detected case was measured. Costs included human resources and materials using a micro-costing evaluation. RESULTS: All bleach-based microscopy approaches detected significantly more cases (between 23.3% for B1 and 25.9% for B1+B2) than the conventional D1+D2 approach (21.0%). Cost per tested case ranged between respectively euro 2.7 and euro 4.5 for B1 and B1+D2+B2. B1 and B1+B2 were the most cost-effective approaches. D1+B2 and D1+B1 were good alternatives to avoid using approaches exclusively based on bleach sedimentation microscopy. CONCLUSIONS: Among several effective microscopy approaches used, including sodium hypochlorite sedimentation, only some resulted in a limited increase in the laboratory workload and would be most suitable for programmatic implementation

Pulse-driven quantum dynamics beyond the impulsive regime

We review various unitary time-dependent perturbation theories and compare them formally and numerically. We show that the Kolmogorov-Arnold-Moser technique performs better owing to both the superexponential character of correction terms and the possibility to optimize the accuracy of a given level of approximation which is explored in details here. As an illustration, we consider a two-level system driven by short pulses beyond the sudden limit.Comment: 15 pages, 5 color figure

Tribological properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere

This work is concerned with the study of the tribologic properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere. The fluorinated compounds all present good intrinsic friction properties (friction coefficient in the range 0.05–0.09). The tribologic performances are optimized if the materials present remaining graphitic domains (influenced by the presence of intercalated fluorinated species) whereas the perfluorinated compounds, where the fluorocarbon layers are corrugated (armchair configuration of the saturated carbon rings) present higher friction coefficients. Raman analyses reveal that the friction process induces severe changes in the materials structure especially the partial re-building of graphitic domains in the case of perfluorinated compounds which explains the improvement of μ during the friction tests for these last materials

Multi-resolution texture classification based on local image orientation

The aim of this paper is to evaluate quantitatively the discriminative power of the image orientation in the texture classification process. In this regard, we have evaluated the performance of two texture classification schemes where the image orientation is extracted using the partial derivatives of the Gaussian function. Since the texture descriptors are dependent on the observation scale, in this study the main emphasis is placed on the implementation of multi-resolution texture analysis schemes. The experimental results were obtained when the analysed texture descriptors were applied to standard texture databases

Chiral molecules split light: Reflection and refraction in a chiral liquid

A light beam changes direction as it enters a liquid at an angle from another medium, such as air. Should the liquid contain molecules that lack mirror symmetry, then it has been predicted by Fresnel that the light beam will not only change direction, but will actually split into two separate beams with a small difference in the respective angles of refraction. Here we report the observation of this phenomenon. We also demonstrate that the angle of reflection does not equal the angle of incidence in a chiral medium. Unlike conventional optical rotation, which depends on the path-length through the sample, the reported reflection and refraction phenomena arise within a few wavelengths at the interface and thereby suggest a new approach to polarimetry that can be used in microfluidic volumes

Functionalized Gold Nanoparticles with Electropolymerizable π-Conjugated Systems for a Neuro-inspired Memristive Nanoparticle Organic Synapse-Transistor

Nanoparticle Organic Memory Field-Effect Transistors (NOMFET) are molecule-based devices that exhibit the main behavior of a biological spiking synapse. This behavior is obtained by virtue of the combination of two properties of the NOMFET: the transconductance gain of the transistor and the memory effect due to the presence of nanoparticles (NPs) which are used as nanoscale capacitors to store the electrical charges, and which are embedded into an organic semiconducting layer [1]. Thus, the transconductance of the transistor can be dynamically tuned by the amount of charge in the NPs. In this context, we present here a novel method for the elaboration of NOMFET active materials based on the electrochemical deposition of gold NPs grafted with alkanethiol-terminated π-conjugated precursors combining low oxidation potential and high reactivity. The straightforward electropolymerization of these new precursors leads to the formation of a semiconducting network in which the electronic and transport properties and the charging/discharging speed of the gold NPs can be modulated. Such hybrid material could advantageously replace the pentacene layer generally used in NOMFETs. This novel approach is based on previously demonstrated enhancement of charge-tunneling across monolayers of SAMs of alkanethiol-bithiophenic systems on a planar gold surface after electrochemical conversion into more extended conjugated systems [2]. The synthesis of the precursors and nanoparticles will be described and the morphology and electronic properties of the hybrid electropolymerized films will be discussed with regard to the behavior of the resulting NOMFET-devices. [1] F. Alibart, S. Pleutin, D. Guerin, C. Novembre, S. Lenfant, K. Lmimouni, C. Gamrat, D. Vuillaume, Adv. Funct. Mater. 2010, 20, 330-337. [2] M. Oçafrain, T. K. Tran, P. Blanchard, S. Lenfant, S. Godey, D. Vuillaume, J. Roncali, Adv. Funct. Mater. 2008, 18, 2163-2171