16 research outputs found
Palaeoecological studies: the role of remote sensing and GIS applications
No full textInternational audienceThis edited volume of proceedings brings together a diversity of papers that presents a multitude of approaches and proxies used in understanding global climatic and environmental changes during the Quaternary period of the earth’s history, focusing on the most recent or “Late Quaternary”. Regionally, the focus is on the south Asian region with contributions from Bangladesh, Sri Lanka and Thailand in addition to the majority from India. The volume is subdivided into 6 sections grouped thematically and comprises papers dealing with diverse themes such as Radiometric dating methods, Geological and Biological proxies, Model specific datasets and data specific models and applications of new technologies such as remote sensing to the study of palaeoenvironments
Multi-level iterative methods and the strengthened CBS inequality
No full textThe paper describe new results obtained by the author in estimates of the strengthened C.B.S. constant for hierarchical decomposition of conforming FE spaces. Also some results for nonconforming FE obtained in collaboration with S. Margenov and M. Neytcheva are mentioned
Deforestation in the Tropics: Reconciling Disparities in Estimates for India
No full textHere we examine recent disparate estimates of deforestation obtained for India. We discuss the sources of disparity and the implications of inaccurate estimates and suggest ways in which future attempts at estimating deforestation might reconcile the disparity. Despite the importance of deforestation and its consequences, no attempt has been made to reconcile the different estimates obtained for India
Arp2/3 complex inhibition radically alters lamellipodial actin architecture, suspended cell shape, and the cell spreading process
No full text© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Molecular Biology of the Cell 26 (2015): 887-900, doi:10.1091/mbc.E14-07-1244.Recent studies have investigated the dendritic actin cytoskeleton of the cell edge's lamellipodial (LP) region by experimentally decreasing the activity of the actin filament nucleator and branch former, the Arp2/3 complex. Here we extend these studies via pharmacological inhibition of the Arp2/3 complex in sea urchin coelomocytes, cells that possess an unusually broad LP region and display correspondingly exaggerated centripetal flow. Using light and electron microscopy, we demonstrate that Arp2/3 complex inhibition via the drug CK666 dramatically altered LP actin architecture, slowed centripetal flow, drove a lamellipodial-to-filopodial shape change in suspended cells, and induced a novel actin structural organization during cell spreading. A general feature of the CK666 phenotype in coelomocytes was transverse actin arcs, and arc generation was arrested by a formin inhibitor. We also demonstrate that CK666 treatment produces actin arcs in other cells with broad LP regions, namely fish keratocytes and Drosophila S2 cells. We hypothesize that the actin arcs made visible by Arp2/3 complex inhibition in coelomocytes may represent an exaggerated manifestation of the elongate mother filaments that could possibly serve as the scaffold for the production of the dendritic actin network.This research was supported by National Science Foundation STEP grant 0856704 to Dickinson College, student/faculty summer research grants from the Dickinson College Research and Development Committee, Laura and Arthur Colwin Summer Research Fellowships from the Marine Biological Laboratory to J.H.H. and C.B.S., National Institutes of Health Grant EB002583 to R.O., and National Science Foundation collaborative research grants to J.H.H. (MCB-1412688) and C.B.S. (MCB-1412734)
Characterization of air–sea interaction processes over the Bay of Bengal during the winter phase of ICARB field experiment
No full textEvidence of stratosphere–troposphere exchange during severe cyclones: a case study over Bay of Bengal, India
No full textThe role of cyclones in atmospheric mixing and troposphere–stratosphere exchange of ozone and relative humidity (RH) is investigated for two severe cyclones PHAILIN and HUDHUD over the Bay of Bengal. Ozone concentration from Microwave Limb Sounder along with RH profiles obtained from Sounder for Probing Vertical Profiles of Humidity instrument aboard Meghatropiques platform, upon analysis at different pressure levels, revealed a rapid increase in RH and ozone concentration from lower troposphere to upper troposphere one day prior to landfall for both cyclones. The Weather Research and Forecasting model based simulations of convergence and divergence were used to estimate mass and momentum exchanges between troposphere and stratosphere which suggest the drastic increase in RH and ozone concentrations in UT due to high convective activity. Variations in the vertical profiles of ozone and RH during cyclonic period acts as a tracer for stratosphere–troposphere exchanges during peak cyclone intensity period
A method for assessing evergreen habitats using phytodiversity and geospatial techniques in tropical rain forests of Southern Western Ghats (India)
No full textInternational audienceWe have used data generated using remote sensing and geographical information systems to categorize habitats, and then determined the relationship between the habitat categorizations and species-distribution patterns. A biologically rich hotspot—Kalakad-Mundanthurai Tiger Reserve, located at Southern Western Ghats, India, was chosen for this study. In order to spatially delineate areas of high species richness/diversity and endemic habitat zones, we have identified evergreen habitats in conjunction with landscape metrics, species assemblage, micro-habitats like slope, topography, species endemism, and proportion of core and edge species. A total of 236 species and 2,920 individuals were recorded using systematic stratified plots of 0.1 ha covering 47 plots. Hierarchical cluster analysis was done using Ward’s method. Plot information was used to identify clusters based on species density. The analysis showed five species assemblages that are quite distinct from each other in terms of dominant species. The distribution of endemic and edge species, land cover heterogeneity, and continuity of patches in these clusters were evaluated to understand the degree of disturbance and intactness at landscape scale. Integration of species assemblages and topography brought out four major elevation-slope complexes. Information on species composition (robust field survey) with spectral (hybrid classification) properties has shown 72% overall accuracy and distinguished four evergreen sub-groups and other land cover classes. The developed approach assumes great importance in the assessment of biodiversity and prioritizing the areas of conservation
Regularized Regression and Density Estimation based on Optimal Transport
No full textThe aim of this paper is to investigate a novel nonparametric approach for estimating and smoothing density functions as well as probability densities from discrete samples based on a variational regularization method with the Wasserstein metric as a data fidelity. The approach allows a unified treatment of discrete and continuous probability measures and is hence attractive for various tasks. In particular, the variational model for special regularization functionals yields a natural method for estimating densities and for preserving edges in the case of total variation regularization. In order to compute solutions of the variational problems, a regularized optimal transport problem needs to be solved, for which we discuss several formulations and provide a detailed analysis. Moreover, we compute special self-similar solutions for standard regularization functionals and we discuss several computational approaches and results. © 2012 The Author(s).The work of M.B. has been supported by the German Science Foundation (DFG) through project Regularization with Singular Energies. C.B.S acknowledges the financial support provided by the Cambridge Centre for Analysis (CCA), the DFG Graduiertenkolleg 1023 Identification in Mathematical Models: Synergy of Stochastic and Numerical Methods and the project WWTF Five senses-Call 2006, Mathematical Methods for Image Analysis and Processing in the Visual Arts. Further, this publication is based on work supported by Award No. KUK-I1-007-43, made by King Abdullah University of Science and Technology (KAUST)
Spatial and temporal variabilities in vertical structure of the Marine Atmospheric Boundary Layer over Bay of Bengal during Winter Phase of Integrated Campaign for Aerosols, gases and Radiation Budget
No full textEstudo do potencial hipoglicemiante da Wilbrandia ebracteata em ratos normais e diabéticos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Farmácia.Wilbrandia ebracteata pertence à família Cucurbitaceae e é popularmente conhecida como taiuiá. Das raízes e folhas da espécie foram isoladas cucurbitacinas e flavonóides C-glicosídeos. Estudos in vitro e in vivo demonstraram atividades analgésica, antiinflamatória e antiulcerogênica das raízes e folhas da planta. Alguns C-glicosídeos presentes nas raízes de W. ebracteata, como vitexina e swertisina mostraram ainda ação antioxidante e inibição de -glicosidases intestinais. O presente trabalho teve como objetivo caracterizar a ação e o mecanismo de ação anti-hiperglicêmica de extratos, frações, subfrações e dos compostos isolados das raízes de W. ebracteata, swertisina e isovitexina, em ratos normais hiperglicêmicos e diabéticos. Foram utilizados ratos Wistar machos adultos entre 50-55 dias em jejum de 16 h prévio ao tratamento. Nos experimentos para determinação da glicemia e da concentração plasmática de insulina, as preparações de W. ebracteata foram administradas em diferentes doses por via oral em ratos normais após sobrecarga de glicose e as determinações foram realizadas nos tempos de 0, 15, 30, 60 e 180 min. O conteúdo de glicogênio muscular foi determinado após 180 min. A glicemia de ratos diabéticos foi determinada nos tempos 0, 1, 2 e 3 h após tratamento. A captação de glicose foi estudada em músculo sóleo na ausência (controle) ou presença dos C-glicosídeos isovitexina e swertisina e/ou insulina (tratado). A administração do extrato bruto metanólico (400 e 800 mg/kg) reduziu a glicemia de ratos normais hiperglicêmicos entre os tempos 15-60 min e elevou a concentração plasmática de insulina entre 30 e 60 min. O aumento do conteúdo de glicogênio muscular também foi observado. A fração n-butanol (50 mg/kg) apresentou maior potência nos tempos 15 e 30 min, entretanto esta fração não alterou a glicemia de ratos diabéticos. Efeito semelhante foi observado para a subfração metanólica. Os flavonóides C-glicosídeos isovitexina e swertisina (15 mg/kg) apresentaram ação anti-hiperglicêmica mais potente que a observada para frações e extratos e não alteraram a captação de glicose em músculo sóleo de ratos normais. A partir dos resultados obtidos, pode-se concluir que os extratos, frações, subfrações e flavonóides C-glicosídeos isolados de W. ebracteata possuem ação anti-hiperglicêmica provavelmente pelo estímulo da secreção de insulina pelo pâncreas
