Search results for "Quantitative"
showing 10 items of 2409 documents
A genetic system based on simulated crossover of sequences of two-bit genes
2006
AbstractWe introduce a genetic model based on simulated crossover of fixed sequences of two-bit genes. Results are(1)a lower bound on population size is exhibited such that a transition takes the stochastic finite population genetic system near the next state of the deterministic infinite population genetic system (provided both begin in the same state);(2)states and dynamics of the deterministic infinite population genetic system are derived for arbitrary (finite) fitness functions (expressed in terms of multivariate polynomials);(3)in the case of quadratic fitness defined by weight matrices with m nonnull entries it is shown that each state transition can be implemented in time O(m+l), wh…
Tilted phases of fatty acid monolayers
1995
X‐ray diffraction data from water‐supported monolayers of fatty acids with chain lengths from 19 to 22 is presented. The structures of the tilted mesophases L2’, L2, and Ov are characterized in detail. The contributions to the unit cell distortion from the tilt and the ordering of the backbone planes of the molecules are separated. It is shown that at the swiveling transition L2’–L2, not only the tilt azimuth but also the packing of the backbone planes change discontinuously. We demonstrate that the tilting transition LS–L2 is accompanied by the ordering of the backbone planes and may be discontinuous. Evidence is presented for a herringbone ordering transition within the L2 region. The dis…
Molecular dynamics simulation of single DNA stretching reveals a novel structure
2005
Abstract MD simulation, to closely mimic a torsionally unconstrained single-molecule stretching experiment of dsDNA, uncovers three distinct force regimes, characterized by fast and slow elongation regions with a transition regime in between, where the α and γ backbone torsion angles of the elongated double-stranded DNA find rapidly new stationary values. In the slow elongation regime DNA gradually looses its twist, collectively breaks all base-pair H-bonds and develops a remarkable base-stacked structure with the bases strongly tilted, forming a zipper-like stack on the major groove side, stabilized by the narrowing distance between the elongated strands, and by specific water interactions.
La mobilité internationale des diplômés de doctorat français : caractéristiques et déterminants
2014
Les études de l'emploi cadre, n°2014-38, avril 2014 En ligne sur : http://recruteurs.apec.fr/Recrutement/content/download/534217/1269090/version/2/file/La+mobilit%C3%A9+internationale+des+dipl%C3%B4m%C3%A9s+de+doctorat+fran%C3%A7ais.pdf; Ce rapport porte sur les facteurs explicatifs de la mobilité internationale de diplômés d'un doctorat en France, à partir de deux enquêtes réalisées en 2011 et 2012 auprès des jeunes docteurs ayant obtenu leur thèse entre 2003 et 2008. Différentes analyses, qualitatives et quantitatives, ont permis d'examiner l'impact des facteurs personnels, professionnels, économiques et scientifiques dans les décisions successives de mobilités après la fin de la thèse.Le…
Evidence of superatom electronic shells in ligand-stabilized aluminum clusters
2011
Ligand-stabilized aluminum clusters are investigated by density functional theory calculations. Analysis of Kohn-Sham molecular orbitals and projected density of states uncovers an electronic shell structure that adheres to the superatom complex model for ligand-stabilized aluminum clusters. In this current study, we explain how the superatom complex electron-counting rule is influenced by the electron-withdrawing ligand and a dopant atom in the metallic core. The results may guide the prediction of new stable ligand-stabilized (superatom) complexes, regardless of core and electron-withdrawing ligand composition.
Column-switching techniques for screening of diuretics and probenecid in urine samples
1994
A method based on high-performance liquid chromatography using column-switching is described for the screening of diuretics and probenecid in urine samples. The system uses a 20- x 2.1-mm i.d. precolumn, packed with a Hypersil ODS-C18, 30-microns stationary phase, for the on-line sample cleanup and enrichment. Untreated urine samples are directly injected, and the precolumn is flushed for 1 min with water to eliminate polar matrix components. The retained analytes are then back-flushed by means of a six-port switching valve onto a Hypersil ODS-C18 analytical column (5 microns, 250- x 4-mm i.d.), where they are separated using an acetonitrile/phosphate buffer (pH = 3) gradient elution. Under…
Basics of anatomy
2017
Peripheral nerves contain motor, sensory, and vegetative fibers that are strictly separate, but in close proximity to each other (Figure 1).
Biopartitioning micellar chromatography: an in vitro technique for predicting human drug absorption.
2001
The main oral drug absorption barriers are fluid cell membranes and generally drugs are absorbed by a passive diffusion mechanism. Biopartitioning micellar chromatography (BMC) is a mode of micellar liquid chromatography that uses micellar mobile phases of Brij35 under adequate experimental conditions and can be useful to mimic the drug partitioning process in biological systems. In this paper the usefulness of BMC for predicting oral drug absorption in humans is demonstrated. A hyperbolic model has been obtained using the retention data of a heterogeneous set of 74 compounds, which shows predictive ability for drugs absorbed by passive diffusion. The model obtained in BMC is compared with …
New antitrichomonal drug-like chemicals selected by bond (edge)-based TOMOCOMD-CARDD descriptors.
2008
Bond-based quadratic indices, new TOMOCOMD-CARDD molecular descriptors, and linear discriminant analysis (LDA) were used to discover novel lead trichomonacidals. The obtained LDA-based quantitative structure-activity relationships (QSAR) models, using nonstochastic and stochastic indices, were able to classify correctly 87.91% (87.50%) and 89.01% (84.38%) of the chemicals in training (test) sets, respectively. They showed large Matthews correlation coefficients of 0.75 (0.71) and 0.78 (0.65) for the training (test) sets, correspondingly. Later, both models were applied to the virtual screening of 21 chemicals to find new lead antitrichomonal agents. Predictions agreed with experimental resu…
Provisional Classification and in Silico Study of Biopharmaceutical System Based on Caco-2 Cell Permeability and Dose Number
2013
Today, early characterization of drug properties by the Biopharmaceutics Classification System (BCS) has attracted significant attention in pharmaceutical discovery and development. In this direction, the present report provides a systematic study of the development of a BCS-based provisional classification (PBC) for a set of 322 oral drugs. This classification, based on the revised aqueous solubility and the apparent permeability across Caco-2 cell monolayers, displays a high correlation (overall 76%) with the provisional BCS classification published by World Health Organization (WHO). Current database contains 91 (28.3%) PBC class I drugs, 76 (23.6%) class II drugs, 97 (31.1%) class III d…