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364 results on '"Roy Shyamal"'

1. Microprocesses of Agglomeration, Hetero-coagulation and Particle Deposition of Poorly Wetted Surfaces in the Context of Metal Melt Filtration and Their Scale Up

Author

Nicklas, Jan, Ditscherlein, Lisa, Roy, Shyamal, Sandfeld, Stefan, Peuker, Urs A., Hull, Robert, Series Editor, Jagadish, Chennupati, Series Editor, Kawazoe, Yoshiyuki, Series Editor, Kruzic, Jamie, Series Editor, Osgood Jr., Richard, Series Editor, Parisi, Jürgen, Series Editor, Pohl, Udo W., Series Editor, Seong, Tae-Yeon, Series Editor, Uchida, Shin-ichi, Series Editor, Wang, Zhiming M., Series Editor, Aneziris, Christos G., editor, and Biermann, Horst, editor

Published
2024
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3. Sintering of Alumina Nanoparticles: Comparison of Interatomic Potentials, Molecular Dynamics Simulations, and Data Analysis

Author

Roy, Shyamal, Prakash, Arun, and Sandfeld, Stefan

Subjects
Condensed Matter - Materials Science
Abstract

Sintering of alumina nanoparticles is of interest both from the view of fundamental research as well as for industrial applications. Atomistic simulations are tailor-made for understanding and predicting the time- and temperature-dependent sintering behaviour. However, the quality and predictability of such analysis is strongly dependent on the performance of the underlying interatomic potentials. In this work, we investigate and benchmark four empirical interatomic potentials and discuss the resulting properties and drawbacks based on experimental and density functional theory data from the literature. The potentials, which have different origins and formulations, are then used in molecular dynamics simulations to perform a systematic study of the sintering process. To analyse the results, we develop a number of tailored data analysis approaches that are able to characterise and quantify the sintering process. Subsequently, the disparities in the sintering behaviour predicted by the potentials are critically discussed. Finally, we conclude by providing explanations for the differences in performance of the potentials, together with recommendations for molecular dynamics sintering simulations of alumina.

Published
2022
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6. Characterizing the spatial and temporal variation of malaria incidence in Bangladesh, 2007

Author

Reid Heidi L, Haque Ubydul, Roy Shyamal, Islam Nazrul, and Clements Archie CA

Subjects
Malaria, Bangladesh, Spatial, Temporal, Seasonality, Bayesian, Plasmodium falciparum, Plasmodium vivax, Arctic medicine. Tropical medicine, RC955-962, Infectious and parasitic diseases, RC109-216
Abstract

Abstract Background Malaria remains a significant health problem in Bangladesh affecting 13 of 64 districts. The risk of malaria is variable across the endemic areas and throughout the year. A better understanding of the spatial and temporal patterns in malaria risk and the determinants driving the variation are crucial for the appropriate targeting of interventions under the National Malaria Control and Prevention Programme. Methods Numbers of Plasmodium falciparum and Plasmodium vivax malaria cases reported by month in 2007, across the 70 endemic thanas (sub-districts) in Bangladesh, were assembled from health centre surveillance reports. Bayesian Poisson regression models of incidence were constructed, with fixed effects for monthly rainfall, maximum temperature and elevation, and random effects for thanas, with a conditional autoregressive prior spatial structure. Results The annual incidence of reported cases was 34.0 and 9.6 cases/10,000 population for P. falciparum and P. vivax respectively and the population of the 70 malaria-endemic thanas was approximately 13.5 million in 2007. Incidence of reported cases for both types of malaria was highest in the mountainous south-east of the country (the Chittagong Hill Tracts). Models revealed statistically significant positive associations between the incidence of reported P. vivax and P. falciparum cases and rainfall and maximum temperature. Conclusions The risk of P. falciparum and P. vivax was spatially variable across the endemic thanas of Bangladesh and also highly seasonal, suggesting that interventions should be targeted and timed according to the risk profile of the endemic areas. Rainfall, temperature and elevation are major factors driving the spatiotemporal patterns of malaria in Bangladesh.

Published
2012
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23. Bone morphogenetic protein 2- and estradiol-17β-induced changes in ovarian transcriptome during primordial follicle formation

Author

Chakraborty, Prabuddha, Anderson, Rebecca L, and Roy, Shyamal K

Subjects
Mice, Estradiol, Reproductive Medicine, Cricetinae, Ovary, Animals, Bone Morphogenetic Protein 2, Female, RNA, Messenger, Cell Biology, General Medicine, Transcriptome, Research Article
Abstract

Estradiol-17β has been shown to promote primordial follicle formation and to involve bone morphogenetic protein 2 (BMP2) as a downstream effector to promote primordial follicle in hamsters. However, the molecular mechanism whereby these factors regulate ovarian somatic cells to pre-granulosa cells transition leading to primordial follicle formation remains unclear. The objective of this study was to determine whether BMP2 and/or estradiol-17β would regulate the expression of specific ovarian transcriptome during pre-granulosa cells transition and primordial follicle formation in the mouse ovary. BMP2 mRNA level increased during the period of primordial follicle formation with the concurrent presence of BMP2 protein in ovarian somatic cells. Estradiol-17β but not BMP2 exposure led to increased expression of ovarian BMP2 messenger RNA (mRNA), and the effect of estradiol-17β could not be suppressed by 4-[6-[4-(1-Piperazinyl)phenyl]pyrazolo[1,5-a]pyrimidin-3-yl]quinoline dihydrochloride (LDN) 193189. BMP2 or estradiol-17β stimulated primordial follicle formation without inducing apoptosis. Ribonucleic acid-sequence analysis (RNA-seq) of ovaries exposed to exogenous BMP2 or estradiol-17β revealed differential expression of several thousand genes. Most of the differentially expressed genes, which were common between BMP2 or estradiol-17β treatment demonstrated concordant changes, suggesting that estradiol-17β and BMP2 affected the same set of genes during primordial follicle formation. Further, we have identified that estradiol-17β, in cooperation with BMP2, could affect the expression of three major transcription factors, GATA binding protein 2, GATA binding protein 4 and Early growth response 2, and one serine protease, hepsin, in pre-granulosa cells during primordial follicle formation. Taken together, results of this study suggest that estradiol-17β and BMP2 may regulate ovarian gene expression that promote somatic cells to pre-granulosa cells transition and primordial follicle formation in the mouse ovary.

Published
2022

49. Comparative analysis of endothelial cell loss following phacoemulsification in pupils of different sizes

Author

Maggon, Rakesh, Bhattacharjee, Raghudev, Shankar, Sandeep, Kar, Rajesh, Sharma, Vivek, and Roy, Shyamal

Subjects
Pupil (Eye) -- Care and treatment, Endothelium -- Research, Phacoemulsification -- Usage, Health
Abstract

Byline: Rakesh. Maggon, Raghudev. Bhattacharjee, Sandeep. Shankar, Rajesh. Kar, Vivek. Sharma, Shyamal. Roy Purpose: To compare Endothelial cell(EC) loss following Phacoemulsification (PKE) in pupils of different sizes. Methods: A prospective [...]

Published
2017

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