49,083 research outputs found
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
Correction to: Visual acuity correlates with multimodal imaging-based categories of central serous chorioretinopathy (Eye, (2021), 10.1038/s41433-021-01788-4)
No full textIn this article the author name Ramesh Venkatesh was incorrectly written as Ramesh Vankatesh. The original article has been corrected
Correction to: Influence of fellow eye on the diagnosis and classification of central serous chorioretinopathy (Graefe's Archive for Clinical and Experimental Ophthalmology, (2021), 10.1007/s00417-021-05435-2)
No full textIn the original published article, one of the author names has been misspelled. “Ramesh Vankatesh” should be “Ramesh Venkatesh” This is being corrected in this publication
"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
Multimodal Imaging Based Predictors for the Development of Choroidal Neovascularization in Patients with Central Serous Chorioretinopathy
No full textThis study evaluated predictors for choroidal neovascularization (CNV) associated with central serous chorioretinopathy (CSCR) based on multimodal imaging. A retrospective multicenter chart review was conducted on 134 eyes of 132 consecutive patients with CSCR. Eyes were classified as per the multimodal imaging-based classification of CSCR at baseline into simple/complex CSCR and primary episode/recurrent/resolved CSCR. Baseline characteristics of CNV and predictors were evaluated with ANOVA. In 134 eyes with CSCR, 32.8% had CNV (n = 44) with 72.7% having complex CSCR (n = 32), 22.7% having simple (n = 10) and 4.5% having atypical (n = 2). Primary CSCR with CNV were older (58 vs. 47, p = 0.00003), with worse visual acuity (0.56 vs. 0.75, p = 0.01) and of longer duration (median 7 vs. 1, p = 0.0002) than those without CNV. Similarly, recurrent CSCR with CNV were older (61 vs. 52, p = 0.004) than those without CNV. Patients with complex CSCR were 2.72 times more likely to have CNV than patients with simple CSCR. In conclusion, CNV associated with CSCR was more likely in complex CSCR and older age of presentation. Both primary and recurrent CSCR are implicated in CNV development. Patients with complex CSCR were 2.72 times more likely to have CNV than patients with simple CSCR. Multimodal imaging-based classification of CSCR supports detailed analysis of associated CNV
Activity of a novel sulfonamide compound 2-nitro-N-(pyridin-2-ylmethyl)benzenesulfonamide against Leishmania donovani
No full textManas R Dikhit,1,* Bidyut Purkait,1,* Ruby Singh,1 Bikash Ranjan Sahoo,2 Ashish Kumar,1 Rajiv K Kar,3 Md Yousuf Ansari,1,4 Savita Saini,1,5 Kumar Abhishek,1 Ganesh C Sahoo,1 Sushmita Das,6 Pradeep Das11Department of Molecular Parasitology and Biomedical Informatics, Rajendra Memorial Research Institute of Medical Sciences, Indian Council of Medical Research, Agamkuan, Patna, Bihar, India; 2Laboratory of Molecular Biophysics, Institute for Protein Research, Osaka University, Japan; 3Biomolecular Nuclear Magnetic Resonance and Drug Design Laboratory, Department of Biophysics, Bose Institute, Kolkata, West Bengal, 4Department of Pharmacoinformatics, 5Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Hajipur, 6Department of Microbiology, All India Institute of Medical Sciences, Patna, Bihar, India*These authors contributed equally to this workAbstract: New treatments for visceral leishmaniasis, caused by Leishmania donovani, are needed to overcome sustained toxicity, cost, and drug resistance. The aim of this study was to evaluate the therapeutic effects of 2-nitro-N-(pyridin-2-ylmethyl)benzenesulfonamide (2NB) against promastigote and amastigote forms of L. donovani and examine its effect in combination with amphotericin B (AmB) against AmB-resistant clinical isolates. Effects were assessed against extracellular promastigotes in vitro and intracellular amastigotes in L. donovani-infected macrophages. Levels of inducible nitric oxide and Th1 and Th2 cytokines were measured in infected 2NB-treated macrophages, and levels of reactive oxygen species and NO were measured in 2NB-treated macrophages. 2NB was active against promastigotes and intracellular amastigotes with 50% inhibitory concentration values of 38.5±1.5 µg/mL and 86.4±2.4 µg/mL, respectively. 2NB was not toxic to macrophages. Parasite titer was reduced by >85% in infected versus uninfected macrophages at a 2NB concentration of 120 µg/mL. The parasiticidal activity was associated with increased levels of Th1 cytokines, NO, and reactive oxygen species. Finally, 2NB increased the efficacy of AmB against AmB-resistant L. donovani. These results demonstrate 2NB to be an antileishmanial agent, opening up a new avenue for the development of alternative chemotherapies against visceral leishmaniasis.Keywords: visceral leishmaniasis, AmB resistance, benzenesulfonamide, ROS, NO, Th1/Th2 cytokine
Optical coherence tomography angiography findings in cystoid macular degeneration associated with central serous chorioretinopathy.
No full textAIM
To describe the optical coherence tomography (OCT) characteristics and to identify and analyse the incidence of choroidal neovascular (CNV) network seen on optical coherence tomography angiography (OCTA) in eyes with cystoid macular degeneration (CMD) associated with central serous chorioretinopathy (CSCR).
METHODS
This was a retrospective, observational study of 29 eyes of 25 patients who were previously diagnosed as CSCR with CMD. Baseline patient characteristics, best-corrected visual acuity (BCVA), evidence of CNV network and its pattern on OCTA, distribution of CMD changes and OCT parameters, such as height of the neurosensory retinal detachment (NSD), presence of double layer sign, central macular thickness, were analysed. The eyes were classified into two groups depending on the presence or absence of CNV network on OCTA. BCVA, OCT parameters and CMD distribution were compared in the two groups at baseline using independent t-test.
RESULT
A total of 13 (44.8 %) eyes had a CNV network, while only 9 out of the 13 eyes had pattern-I CNV. Among the eyes with CNV network (13 eyes), mean height of NSD was of 65.2±22.7 µ, whereas, among the eyes without CNV (16 eyes), it was 134.6±77.4 µ. The difference was statistically significant (p=0.013). There was no statistically significant difference between eye having a CNV and eyes without CNV in terms of other parameters.
CONCLUSION
A CNV network is seen in a large subset of patients with CMD in CSCR. A shallower subretinal fluid may point towards the presence of an underlying CNV network
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