44,752 research outputs found
Dependence of Electron-Impact Excitation Cross-Sections on the Initial Vibrational Quantum Number in H-2 and D2 Molecules - X(1)Sigma-G+-]B(1)Sigma-U+ and X(1)Sigma-G+-]C(1)Pi-U Transitions
No full textElectron-impact excitation cross sections have been calculated using the impact-parameter method for X1SIGMA(g)+-->B1SIGMA(u)+ and X1SIGMA(g)+-->C1PI(u) transitions for both H-2 and D2 molecules as a function of incident energy and of vibrational quantum number v(i). The results show that the cross sections initially increase monotonically with increasing v(i) and follow the opposite trend for higher v(i) values
Relapsing Neurological Complications in a Child With ATP1A3 Gene Mutation and Influenza Infection: A Case Report
No full textMutations in the ATP1A3 gene encoding the α3 subunit of Na+/K+-ATPase are associated with different neurological manifestations that may be elicited by febrile episodes. A recently described phenotype, linked to the p.Arg756Cys mutation, is clinically characterized by Relapsing Encephalopathy with Cerebellar Ataxia (RECA). In our case, a diagnosis of RECA has been established, and despite an alternative, reasonable cause had been already identified. We describe the case of a child with two recurrent episodes, 2 years apart, of hypotonia and ataxia. In both episodes, a laboratory-confirmed influenza virus infection suggested the diagnosis of influenza-associated encephalopathy. After the second episode, a search for genetic mutations was performed, and ATP1A3 mutation associated to RECA was found. After both episodes, the child was discharged after partial improvement of neurological conditions. The diagnosis of encephalopathy in children is often challenging. A genetic predisposition to neurological decompensation should be suspected in case of recurrent episodes, even if an alternative diagnosis has been established. Indeed, febrile infections may only represent the trigger of neurological involvement. In these patients, the knowledge of a genetic predisposing factors may help in the prevention of neurological episodes by the prompt use of anti-pyrectics and preventive measures as appropriate vaccination
Minimum Time Broadcast in Faulty Star Networks
No full textAbstractIn this paper we give new results on the fault-tolerance capabilities of the star graph. We first consider the problem of determining the maximum number r(n) of vertices in a n! vertices star graph Sn such that by removing any set of vertices and/or edges from Sn of cardinality at most r(n) the diameter of Sn does not increase. Subsequently, we give an algorithm for broadcasting a message in Sn in optimal time (the diameter of Sn) and using the minimum possible number of message transmissions, i.e., n! − 1, in presence of up to r(n) vertex or edge faults, assuming the set of faults is known to all vertices of the network. We also extend this result to the case in which there is no global knowledge on the faulty elements
Laguerre geometry of hypersurfaces in R-n
No full textLaguerre geometry of surfaces in R-3 is given in the book of Blaschke [Vorlesungen uber Differentialgeometrie, Springer, Berlin Heidelberg New York (1929)], and has been studied by Musso and Nicolodi [Trans. Am. Math. soc. 348, 4321-4337 (1996); Abh. Math. Sem. Univ. Hamburg 69, 123-138 (1999); Int. J. Math. 11(7), 911-924 (2000)], Palmer [Remarks on a variation problem in Laguerre geometry. Rendiconti di Mathematica, Serie VII, Roma, vol. 19, pp. 281-293 (1999)] and other authors. In this paper we study Laguerre differential geometry of hypersurfaces in R-n. For any umbilical free hypersurface x:M -> R-n with non-zero principal curvatures we define a Laguerre invariant metric g on M and a Laguerre invariant self-adjoint operator S:TM -> TM, and show that {g,S} is a complete Laguerre invariant system for hypersurfaces in R-n with >= 4. We calculate the Euler-Lagrange equation for the Laguerre volume functional of Laguerre metric by using Laguerre invariants. Using the Euclidean space R-n, the semi-Euclidean space R-1(n) and the degenerate space R-0(n) we define three Laguerre space forms URn, UR1n and UR0n and define the Laguerre embeddings URn1 -> URn and UR0n -> URn, analogously to what happens in the Moebius geometry where we have Moebius space forms S-n, H-n and R-n (spaces of constant curvature) and conformal embeddings H-n -> S-n and R-n -> S-n[cf. Liu et al. in Tohoku Math. J. 53, 553-569 (2001) and Wang in Manuscr. Math. 96, 517-534 (1998)]. Using these Laguerre embeddings we can unify the Laguerre geometry of hypersurfaces in R-n, R-1(n) and R-0(n). As an example we show that minimal surfaces in R-1(3) or R-0(3) are Laguerre minimal in R-3.MathematicsSCI(E)0ARTICLE173-9512
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Experimental investigation into the effect of substrate clamping on the piezoelectric behaviour of thick-film PZT elements
No full textThis paper details an experimental investigation of the clamping effect associated with thick-film piezoelectric elements printed on a substrate. The clamping effect reduces the measured piezoelectric coefficient, d33, of the film. This reduction is due to the influence of the d31 component in the film when a deformation of the structure occurs, by either the direct or indirect piezoelectric effect. Theoretical analysis shows a reduction in the measured d33 of 62%, i.e. a standard bulk lead zirconate titanate (PZT)-5H sample with a manufacturer specified d33 of 593pC/N would fall to 227.8pC/N. To confirm this effect, the d33 coefficients of five thin bulk PZT-5H samples of 220µm thickness were measured before and after their attachment to a metallized 96% alumina substrate. The experimental results show a reduction in d33 of 74% from 529pC/N to 139pC/N. The theoretical analysis was then applied to existing University of Southampton thick-film devices. It is estimated that the measured d33 value of 131pC/N of the thick-film devices is the equivalent of an unconstrained d33 of 345pC/N
R-matrix calculations of low-energy electron alkane collisions
No full textAb initio electron scattering calculations are presented for methane, ethane and propane with particular emphasis on elastic cross sections. Calculations are performed with the Quantemol-N expert system which runs the UK polyatomic R-matrix code. These calculations are presented which systematically increase the size of the coupled states expansion which is used to represent polarisation effects in the scattering wave function. Agreement with experimental measurements is obtained provided sufficient coupled states are included in the expansion. Whether these coupled states expansions really converge the polarisation potential and the prospects for further calculations are discussed. (c) 2007 Elsevier B.V. All rights reserved
Dynamic imaging of dendritic cell extension into the small bowel lumen in response to epithelial cell TLR engagement
No full textCells lining the gastrointestinal tract serve as both a barrier to and a pathway for infectious agent entry. Dendritic cells (DCs) present in the lamina propria under the columnar villus epithelium of the small bowel extend processes across this epithelium and capture bacteria, but previous studies provided limited information on the nature of the stimuli, receptors, and signaling events involved in promoting this phenomenon. Here, we use immunohistochemical as well as dynamic explant and intravital two-photon imaging to investigate this issue. Analysis of CD11c-enhanced green fluorescent protein (EGFP) or major histocompatibility complex CII-EGFP mice revealed that the number of trans-epithelial DC extensions, many with an unusual "balloon" shape, varies along the length of the small bowel. High numbers of such extensions were found in the proximal jejunum, but only a few were present in the terminal ileum. The extensions in the terminal ileum markedly increased upon the introduction of invasive or noninvasive Salmonella organisms, and chimeric mouse studies revealed the key role of MyD88-dependent Toll-like receptor (TLR) signaling by nonhematopoietic (epithelial) elements in the DC extension response. Collectively, these findings support a model in which epithelial cell TLR signaling upon exposure to microbial stimuli induces active DC sampling of the gut lumen at sites distant from organized lymphoid tissues
L'importanza dei nutriceutici: un'indagine dell'Associazione Donne Dermatologhe Italiane
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