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Dramatic Influence (dramatic + influence)

Distribution by Scientific Domains
Chemistry37%

Selected Abstracts

Dramatic Influence of the Electronic Structure on the Conductivity through Open- and Closed-Shell Molecules

ADVANCED MATERIALS, Issue 10-11 2009
Núria Crivillers
The conductivity through two self-assembled monolayers (SAMs) on gold based on the closed-and open-shell form of a polychlorotriphenylmethyl (PTM) derivative were investigated using 3D-mode conductive scanning force microscopy, and striking differences were observed, caused by their highly distinct electronic structure. [source]

Viral meningoencephalitis: a review of diagnostic methods and guidelines for management

EUROPEAN JOURNAL OF NEUROLOGY, Issue 8 2010
I. Steiner
Background:, Viral encephalitis is a medical emergency. The prognosis depends mainly on the pathogen and host immunologic state. Correct immediate diagnosis and introduction of symptomatic and specific therapy has a dramatic influence upon survival and reduces the extent of permanent brain injury. Methods:, We searched the literature from 1966 to 2009. Recommendations were reached by consensus. Where there was lack of evidence but consensus was clear, we have stated our opinion as good practice points. Recommendations:, Diagnosis should be based on medical history and examination followed by CSF analysis for protein and glucose levels, cellular analysis, and identification of the pathogen by polymerase chain reaction amplification (recommendation level A) and serology (level B). Neuroimaging, preferably by MRI, is essential (level B). Lumbar puncture can follow neuroimaging when immediately available, but if this cannot be performed immediately, LP should be delayed only under unusual circumstances. Brain biopsy should be reserved only for unusual and diagnostically difficult cases. Patients must be hospitalized with easy access to intensive care units. Specific, evidence-based, antiviral therapy, acyclovir, is available for herpes encephalitis (level A) and may also be effective for varicella-zoster virus encephalitis. Ganciclovir and foscarnet can be given to treat cytomegalovirus encephalitis, and pleconaril for enterovirus encephalitis (IV class evidence). Corticosteroids as an adjunct treatment for acute viral encephalitis are not generally considered to be effective, and their use is controversial, but this important issue is currently being evaluated in a large clinical trial. Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management. [source]

Viral encephalitis: a review of diagnostic methods and guidelines for management

EUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2005
I. Steiner
Viral encephalitis is a medical emergency. The spectrum of brain involvement and the prognosis are dependent mainly on the specific pathogen and the immunological state of the host. Although specific therapy is limited to only several viral agents, correct immediate diagnosis and introduction of symptomatic and specific therapy has a dramatic influence upon survival and reduces the extent of permanent brain injury in survivors. We searched MEDLINE (National Library of Medicine) for relevant literature from 1966 to May 2004. Review articles and book chapters were also included. Recommendations are based on this literature based on our judgment of the relevance of the references to the subject. Recommendations were reached by consensus. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. Diagnosis should be based on medical history, examination followed by analysis of cerebrospinal fluid for protein and glucose contents, cellular analysis and identification of the pathogen by polymerase chain reaction (PCR) amplification (recommendation level A) and serology (recommendation level B). Neuroimaging, preferably by magnetic resonance imaging, is an essential aspect of evaluation (recommendation level B). Lumbar puncture can follow neuroimaging when immediately available, but if this cannot be obtained at the shortest span of time it should be delayed only in the presence of strict contraindications. Brain biopsy should be reserved only for unusual and diagnostically difficult cases. All encephalitis cases must be hospitalized with an access to intensive care units. Supportive therapy is an important basis of management. Specific, evidence-based, anti-viral therapy, acyclovir, is available for herpes encephalitis (recommendation level A). Acyclovir might also be effective for varicella-zoster virus encephalitis, gancyclovir and foscarnet for cytomegalovirus encephalitis and pleconaril for enterovirus encephalitis (IV class of evidence). Corticosteroids as an adjunct treatment for acute viral encephalitis are not generally considered to be effective and their use is controversial. Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management. [source]

Skill Formation and Utilisation in the Post-Soviet Transition: Higher Education Planning in Post-Soviet Georgia

HIGHER EDUCATION QUARTERLY, Issue 2 2010
Irakli GvaramadzeArticle first published online: 1 MAR 2010
Changes in the former Soviet system had a dramatic influence on higher education in Georgia. The main objective of the current article is to analyse implications of the post-Soviet transition for the skill formation and skill utilisation system in Georgia. In particular, the study analyses recent trends in Georgian higher education including privatisation and economic liberalisation. The discussion builds upon theories of transition and relevance of skill formation theories to the post-Soviet transition. The article argues that increasing competition among public universities and newly emerged private universities has not improved the quality of higher education provision. On the contrary, it has contributed to an imbalance between the labour market's demand for skills and awarded qualifications, a mismatch and irrelevance of skills and high unemployment rates among university graduates. The article demonstrates that economic approaches in the transition context could not explain the complex logic between the skill formation and skill utilisation mechanisms. It further concludes that the discrepancies between the skill formation and skill utilisation systems had a negative impact upon skill modernisation in Georgia. [source]

Lower bound limit analysis with adaptive remeshing

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005
Andrei V. Lyamin
Abstract The objective of this work is to present an adaptive remeshing procedure for lower bound limit analysis with application to soil mechanics. Unlike conventional finite element meshes, a lower bound grid incorporates statically admissible stress discontinuities between adjacent elements. These discontinuities permit large stress jumps over an infinitesimal distance and reduce the number of elements needed to predict the collapse load accurately. In general, the role of the discontinuities is crucial as their arrangement and distribution has a dramatic influence on the accuracy of the lower bound solution (Limit Analysis and Soil Plasticity, 1975). To ensure that the discontinuities are positioned in an optimal manner requires an error estimator and mesh adaptation strategy which accounts for the presence of stress singularities in the computed stress field. Recently, Borges et al. (Int. J. Solids Struct. 2001; 38:1707,1720) presented an anisotropic mesh adaptation strategy for a mixed limit analysis formulation which used a directional error estimator. In the present work, this strategy has been tailored to suit a discontinuous lower bound formulation which employs the stresses and body forces as primary unknowns. The adapted mesh has a maximum density of discontinuities in the direction of the maximum rate of change in the stress field. For problems involving strong stress singularities in the boundary conditions (e.g. a strip footing), the automatic generation of discontinuity fans, centred on the singular points, has been implemented. The efficiency of the proposed technique is demonstrated by analysis of two classical soil mechanics problems; namely the bearing capacity of a rigid strip footing and the collapse of a vertical cut. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Effects of Methyl Substituents on the Activity and Enantioselectivity of Homobenzotetramisole-Based Catalysts in the Kinetic Resolution of Alcohols

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
Yuhua Zhang
Abstract Substitution of the tetrahydropyrimidine ring in the enantioselective acyl transfer catalyst homobenzotetramisole (HBTM) 6 with methyl groups exerts a dramatic influence on its performance in the kinetic resolution of secondary alcohols. The syn- 3-methyl analogue of HBTM (9a) has proved to be superior to the parent compound in terms of catalytic activity, enantioselectivity, and synthetic accessibility. [source]

Electron ionization mass spectra of phosphorus-containing heterocycles.

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2006

The electron ionization mass spectra of 27 cis - and trans -annelated 1,4,4a,5,6,7,8,8a-octahydro-2H -3,1,2-benzoxazaphosphinine 2-oxides were recorded to clarify the effects of the ring heteroatom (O or N), ring annelation, the P configuration and the substituents attached to the ring or to the N and P atoms. For compounds 1,12 different alkyl radical and alkene losses and the cleavage of the P,heteroatom bonds, instead of the P,C bonds, were representative and dependent mainly on the substitution on the N and P atoms. The replacement of Ph and OPh by N(CH2CH2Cl)2 on the P atom had a dramatic influence on the fragmentation process: new fragment ions were obtained and very little M+. (1,3%) was formed. Only slight differences were found between some of the corresponding isomers, but interestingly the compounds formed clear groups on the basis of the differences in their fragmentation, depending on the ring-N and ring-P substituents. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Ultrafast Photoisomerization of Photoactive Yellow Protein Chromophore Analogues in Solution: Influence of the Protonation State

CHEMPHYSCHEM, Issue 8 2006
Agathe Espagne Dr.
Abstract We investigate solvent viscosity and polarity effects on the photoisomerization of the protonated and deprotonated forms of two analogues of the photoactive yellow protein (PYP) chromophore. These are trans- p -hydroxybenzylidene acetone and trans- p -hydroxyphenyl cinnamate, studied in solutions of different polarity and viscosity at room temperature, by means of femtosecond fluorescence up-conversion. The fluorescence lifetimes of the protonated forms are found to be barely sensitive to solvent viscosity, and to increase with increasing solvent polarity. In contrast, the fluorescence decays of the deprotonated forms are significantly slowed down in viscous media and accelerated in polar solvents. These results elucidate the dramatic influence of the protonation state of the PYP chromophore analogues on their photoinduced dynamics. The viscosity and polarity effects are, respectively, interpreted in terms of different isomerization coordinates and charge redistribution in S1. A trans-to-cis isomerization mechanism involving mainly the ethylenic double-bond torsion and/or solvation is proposed for the anionic forms, whereas "concerted" intramolecular motions are proposed for the neutral forms. [source]