169,885 research outputs found
FREE WORK IDENTITY AND NONLINEAR INSTABILITY IN FLUIDS WITH FREE BOUNDARIES
No full textWe study
nonlinear stability in the mean of rest state of viscous or inviscid
fluids, and the nonlinear asyptotic decay of perturbations to rest state of viscous fluids
Insight into the Properties of Cardiolipin Containing Bilayers from Molecular Dynamics Simulations, Using a Hybrid All-Atom/United-Atom Force Field
No full textReprint Address: Chipot, C (reprint author), Univ Talca, Ctr Bioinformat & Simulac Mol, Fac Ingn Bioinformat, 2 Norte 685,Casilla 721, Talca, Chile.Simulation of three models of cardiolipin (CL) containing membranes using a new set of parameters for tetramyristoyl and tetraoleoyl CLs has been developed in the framework of the united-atom CHARMM27-UA and the all-atom CHARMM36 force fields with the aim of performing molecular dynamics (MD) simulations of cardiolipin-containing mixed-lipid membranes. The new parameters use a hybrid representation of all-atom head groups in conjunction with implicit-hydrogen united-atom (UA) to describe the oleoyl and myristoyl chains of the CLs, in lieu of the fully atomistic description, thereby allowing longer simulations to be undertaken. The physicochemical properties of the bilayers were determined and compared with previously reported data. Furthermore, using tetramyristoyl CL mixed with POPG and POPE lipids, a mitochondrial membrane was simulated. The results presented here show the different behavior of the bilayers as a result of the lipid composition, where the length of the acyl chain and the conformation of the headgroup can be associated with the mitochondrial membrane properties. The new hybrid CL parameters prove to be well suited for the simulation of the molecular structure of CL-containing bilayers and can be extended to other lipid bilayers composed of CLs with different acyl chains or alternate head groups
Numerical analysis of microstructures: the influence of incompatibility
No full textWe are concerned with the appearance of microstructures in some problems of Calculus of Variations experiencing ‘wells’ or minimum of energy. Using piecewise linear finite elements, we give energy estimates and analyze their dependence on the incompatibility of the wells
Analyse numérique de problèmes non convexes à donnée au bord non linéaire
No full textIn this thesis, we study a kind of non-convex varaitional problems. Such problems originated in material science, for example in crystal, etc. We consider the following problems : inf#(*(x)) dx; inf#(*(x))+((x)a(x)) dx on certain Sobolev space w#1#p(a) and where the energy density posses energy wells, say w1 i=1,...k. In general, such problems can be no classical solution. In our studies, the numerical method introduced by M. Chipot, C. Collins and D. Kinderlerer has been developped. In section 1 and 2 some results of estimation in a space of finit-element are obtained. Section 3 is contributed to an analysis or parametrized measure. We get a result of Young measure which showing the existence and uniqueness of the generalized solution. And in section 4, we have some estimation results in terms of probability, which explains the behavior of the minimising sequencesCe travail porte sur l'étude des problèmes non convexes. Ils interviennent dans le domaine des matériaux, par exemple cristaux, etc. Nous considérons les problèmes suivants : inf#(*(x)) dx; inf#(*(x))+((x)a(x)) dx sur certains espaces de Sobolev w#1#p(a) et ou la densité d'énergie possède des puits de potentiels. En général, de tels problèmes n'admettent pas de solution classique. Sur cette étude, une approche, introduite par M. chipot, C. collins et D. kinderlerer, a été développée. Dans les sections 1 et 2, des résultats d'estimations dans l'espace des éléments-finis ont été obtenus. La section 3 est consacrée à une analyse paramétrée. On obtient un résultat de la mesure de Young qui décrit l'existence et l'unicité de la solution généralisée. Enfin dans la section 4, des estimations au point de vue probabiliste ont été déduits, et expliquent le comportement des suites minimisante
Asymptotic behavior of nonlinear parabolic problems with periodic data
No full textWe consider parabolic problems with periodic data in space. We study the asymptotic behavior of the solution when the size of the domain on which the problem is set becomes unbounded
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
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