Bio-inspired optimization & sampling technique for side-chain packing in MCCE

The prediction of proteins' conformation helps to understand their exhibited functions, allows for modeling and allows for the possible synthesis of the studied protein. Our research is focused on a sub-problem of protein folding known as side-chain packing. Its computational complexity has been proven to be NP-Hard. The motivation behind our study is to offer the scientific community a means to obtain faster conformation approximations for small to large proteins over currently available methods. As the size of proteins increases, current techniques become unusable due to the exponential nature of the problem. We investigated the capabilities of a hybrid genetic algorithm / simulated annealing technique to predict the low-energy conformational states of various sized proteins and to generate statistical distributions of the studied proteins' molecular ensemble for pKa predictions. Our algorithm produced errors to experimental results within .acceptable margins and offered considerable speed up depending on the protein and on the rotameric states' resolution used

Partager le travail scientifique à l'âge numérique.

National audienceCe texte s'intéresse au changement profond qu'a connu la publication scientifique sur une génération de chercheurs. Cette apparition du document numérique s'est accompagnée d'une mise en ligne progressive mais surtout le document a évolué : il est devenu hypertexte, multimédia (son, vidéo) ou logiciel exécutable sans oublier les données d'expérimentations et les cours en ligne qui deviennent à leur tour publications. C'est en fait la nature même de la publication scientifique qui est bouleversée par l'apparition de ces documents 3.0

Dye-Sensitized Solar Cells Employing a Single Film of Mesoporous TiO2 Beads Achieve Power Conversion Efficiencies Over 10%

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Effects of AV delay programming on ventricular resynchronisation: role of radionuclide ventriculography

Purpose: Optimal atrioventricular delay (AVD) setting for cardiac resynchronisation therapy, i.e. biventricular pacing in patients with heart failure, remains a formidable challenge. Thus, the purpose of this study was to evaluate the effects of different AVD on inter- and intra-ventricular resynchronisation using phase histograms of radionuclide ventriculography (RNV). Methods: In 17 consecutive patients (mean age 64 ± 6years), RNV was performed 236 ± 350days after pacemaker implantation for cardiac resynchronisation therapy. Images were acquired during atrial pacing at 80bpm and during biventricular pacing with AVD ranging from 80 to 160ms. Inter-ventricular dyssynchrony was measured by the delay between the mean phase angles of the left and right ventricles. Intra-ventricular dyssynchrony was measured by the standard deviation (SD) of left ventricular phase histograms. Results: Left ventricular (LV) ejection fraction (EF) was inversely correlated to LV dyssynchrony (SD of LV phase histogram, R = −0.82, p < 0.0001). However, the increase in LVEF by biventricular pacing (mean +4.4 ± 4%) showed only modest correlation to the resulting resynchronisation effect (characterised by a −13 ± 8° decrease in LV phase histogram SD, R = −0.38, p < 0.0001). Conclusion: RNV is helpful in optimising pacing parameters for resynchronisation therapy. Varying AVD did not have a major impact on intra- or inter-ventricular resynchronisation. Thus, the benefit of AVD-based LVEF optimisation seems to result from atrioventricular resynchronisatio

Real Homotopy Theory of Semi-Algebraic Sets

We complete the details of a theory outlined by Kontsevich and Soibelman that associates to a semi-algebraic set a certain graded commutative differential algebra of "semi-algebraic differential forms" in a functorial way. This algebra encodes the real homotopy type of the semi-algebraic set in the spirit of the DeRham algebra of differential forms on a smooth manifold. Its development is needed for Kontsevich's proof of the formality of the little cubes operad.Comment: 58 pages. Cosmetic changes with respect to previous version. Submitte

Plutonium in the environment: key factors related to impact assessment in case of an accidental atmospheric release

International audienceThis paper deals with plutonium and key factors related to impact assessment. It is based on recent work performed by CEA which summarize the main features of plutonium behaviour from sources inside installations to the environment and man, and to report current knowledge on the different parameters used in models for environmental and radiological impact assessment. These key factors are illustrated through a case study based on an accidental atmospheric release of Pu in a nuclear facility

Electron donor-acceptor distance dependence of the dynamics of light-induced interfacial charge transfer in the dye-sensitization of nanocrystalline oxide semiconductors

The effect of electronic and nuclear factors on the dynamics of dye-to-semiconductor electron transfer was studied employing RuII(terpy)(NCS)3 sensitizers grafted onto transparent films made of titanium dioxide nanoparticles. Various approaches were strived to understand the dependence of the kinetics of charge injection and recombination processes upon the distance separating the dye molecules and the redox active surface. A series of bridged sensitizers containing p- phenylene spacers of various lengths and phosphonic anchoring groups were adsorbed onto TiO2 films. The kinetics of interfacial charge transfer was recorded by use of time-resolved spectroscopy in the fs-ps domain. The electron injection process was found to be biphasic with a clear exponential distance dependence of the fast kinetic component. The slower part of the kinetics was essentially unaffected by the length of the spacer bridge and was attributed to sensitizer molecules that are weakly bound to the surface with no direct contact of the anchoring group with the semiconductor. In a second approach, the kinetics of both forward- and back-electron transfer across a layer of insulating Al2O3 deposited onto TiO2 nanocrystalline particles was investigated. Efficient charge injection was observed over distances up to 3 nm

Test 1157: John Deere 2630 and 2640 Diesel

EXPLANATION OF TEST REPORT GENERAL CONDITIONS East tractor is a production model equipped for common usage. Power consuming accessories can be disconnected only when it is convenient for the operator to do so in practice. Additional weight can be added as ballast if the manufacturer regularly supplies it for sale. The static tire loads and the inflation pressures muse conform to recommendations in the Tire Standards published by the Society of Automotive Engineers. PREPARATION FOR PERFORMANCE RUNS The engine crank case is drained and refilled with a measured amount of new oil conforming to specifications in the operator’s manual. The fuel used and the maintenance operations must also conform to the published information delivered with the tractor. The tractor is then limbered-up for 1 hour on drawbar work in accordance with the manufacturers published recommendations. The manufacturer’s representative is present to make appropriate decisions regarding mechanical adjustments. The tractor is equipped with approximately the amount of added ballast that is used during maximum drawbar tests. The tire tread-bar height must be at least 65% of new tread height prior to the maximum power run. BELT OR POWER TAKE-OFF PERFORMANCE Maximum Power and Fuel Consumption. The manufacturer’s representative makes carburetor, fuel pump, ignition and governor control settings which remain unchanged throughout tall subsequent runs. The governor and the manually operated governor control lever is set to provide the high-idle speed specified by the manufacturer for maximum power. Maximum power is measured by connecting the belt pulley or the power take-off to a dynamometer. The dynamometer load is then gradually increased until the engine is operating at the rated speed specified by the manufacturer for maximum power. The corresponding fuel consumption is measured. Varying Power and Fuel Consumption. Six different horsepower levels are used to show corresponding fuel consumption rates and how the governor causes the engine to react to the following changes in dynamometer load: 85% of the dynamometer torque at maximum power; minimum dynamometer torque, ½ the 85% torque; maximum power; ¼ and ¾ of the 85% torque. Since at tractor is generally subjected to varying loads the average of the results in this test serve well for predicting the fuel consumption of a tractor in general usage. DRAWBAR PERFORMANCE All engine adjustments are the same as those used in the belt or power take-off tests. If the manufacturer specifies a different rated crankshaft speed for drawbar operations, then the position of the manually operated governor control is changed to provide the high-idle speed specified by the manufacturer in the operating instructions. Varying Power and Fuel Consumption With Ballast. The varying power runs are made to show the effect of speed-control devices (engine governor, automatic transmissions, etc.) on horsepower, speed and fuel consumption. These runs are made around the entire test course with has two 180 degree turns with a minimum radius of 50 feet. The drawbar pull is set at 3 different levels as follows: (1) as near to the pull a maximum power as possible and still have the tractor maintain the travel speed at maximum horsepower on the straight sections of the test course; (2) 75% of the pull at maximum power; and (3) 50% of the pull at maximum power. Prior to 1958, fuel consumption data (10 hour test) were shown only for the pull obtained at maximum power for tractors having torque converters and at 75% of the pull obtained at maximum power for gear-type tractors. Maximum Power With Ballast. Maximum power is measured on straight level sections of the test course. Data are shown for not more that 12 different gears or travel speeds. Some gears or travel speeds may be omitted because of high slippage of the traction members or because the travel speed may exceed the safe-limit for the test course. The maximum safe speed for the Nebraska Test course has been set at 15 miles per hour. The slippage limits have been set at 15% and 7% for pneumatic tires and steel tracks or lugs, respectively. Higher slippage gives widely varying results. Maximum Power Without Ballast. All added ballast is removed from the tractor. The maximum drawbar power of the tractor is determined by the same procedure used for getting maximum power with ballast. The gear (or travel speed) is the same as that used in the 10-hours test. Varying Power and Travel Speed With Ballast. Travel speeds corresponding to drawbar pulls beyond the maximum power range are obtained to show the “lugging ability” of the tractor. The run starts with the pull at maximum power; then additional drawbar pull is applied to cause decreasing speeds. The run is ended by one of three conditions; (1) maximum pull is obtained, (2) the maximum slippage limit is reached, or (3) some other operating limit is reached

Stable dye-sensitized solar cells based on organic chromophores and ionic liquid electrolyte

A series of polyene-diphenylaniline based organic dyes (coded as D5, D7, D9 and D11) have been reported for the application in ionic liquid electrolyte based dye-sensitized solar cells. The effects of substitution of organic dyes on the photovoltaic performance have been investigated, which show addition of methoxy groups on the triphenylamine donor group increases short-circuit current, open-circuit voltage and photovoltaic performance. A power conversion efficiency of 6.5% under AM 1.5 sunlight at 100 mW/cm(2) has been obtained with D11 dye in combination with a binary ionic liquid electrolyte, which when subjected to accelerated testing under one sun light soaking at 60 degrees C, the efficiency remained 90% of initial efficiency. (C) 2011 Elsevier Ltd. All rights reserved

New pyrido[3,4-b]pyrazine-based sensitizers for efficient and stable dye-sensitized solar cells

A series of new pyrido[3,4-b]pyrazine-based organic sensitizers (PP-I and APP-I–IV) containing different donors and p-spacers have been synthesized and employed in dye-sensitized solar cells (DSSCs). The absorption spectra properties of dyes are analysed by density functional theory (DFT). The calculated results in combination with the experiments suggest that the absorption characteristics and excited state features will mainly be dominated by charge transfer transitions from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) and to higher LUMO orbitals. Furthermore, attaching the octyloxy groups significantly extends the π-conjugation of the donor in APP- IV, which raises the HOMO energy and facilitates its oxidation. As a consequence, APP-IV exhibits the lowest HOMO–LUMO energy gap among all dyes, which, in turn, corresponds well with the red shift of the absorption spectra. Transient photovoltage and photocurrent decay experiments as well as electrochemical impedance spectroscopy indicate that the electron lifetime and charge recombination resistance are increased due to the introduction of octyloxy chains on the donor unit, resulting in the high photovoltage based on APP-IV. It was found that APP-IV based DSSCs with liquid electrolyte display the highest power conversion efficiency (PCE) of 7.12%. Importantly, a PCE of 6.20% has been achieved for APP-IV based DSSCs with ionic-liquid electrolytes and retained 97% of the initial value after continuous light soaking for 1000 h at 60 C. This renders these pyrido[3,4-b]pyrazine-based sensitizers quite promising candidates for highly efficient and stable DSSCs