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Search Results: 1 - 10 of 3336 matches for " Souparno Ghosh "
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Scaling Integral Projection Models for Analyzing Size Demography
Alan E. Gelfand,Souparno Ghosh,James S. Clark
Statistics , 2013, DOI: 10.1214/13-STS444
Abstract: Historically, matrix projection models (MPMs) have been employed to study population dynamics with regard to size, age or structure. To work with continuous traits, in the past decade, integral projection models (IPMs) have been proposed. Following the path for MPMs, currently, IPMs are handled first with a fitting stage, then with a projection stage. Model fitting has, so far, been done only with individual-level transition data. These data are used in the fitting stage to estimate the demographic functions (survival, growth, fecundity) that comprise the kernel of the IPM specification. The estimated kernel is then iterated from an initial trait distribution to obtain what is interpreted as steady state population behavior. Such projection results in inference that does not align with observed temporal distributions. This might be expected; a model for population level projection should be fitted with population level transitions.
A generalized linear mixed model for longitudinal binary data with a marginal logit link function
Michael Parzen,Souparno Ghosh,Stuart Lipsitz,Debajyoti Sinha,Garrett M. Fitzmaurice,Bani K. Mallick,Joseph G. Ibrahim
Statistics , 2011, DOI: 10.1214/10-AOAS390
Abstract: Longitudinal studies of a binary outcome are common in the health, social, and behavioral sciences. In general, a feature of random effects logistic regression models for longitudinal binary data is that the marginal functional form, when integrated over the distribution of the random effects, is no longer of logistic form. Recently, Wang and Louis [Biometrika 90 (2003) 765--775] proposed a random intercept model in the clustered binary data setting where the marginal model has a logistic form. An acknowledged limitation of their model is that it allows only a single random effect that varies from cluster to cluster. In this paper we propose a modification of their model to handle longitudinal data, allowing separate, but correlated, random intercepts at each measurement occasion. The proposed model allows for a flexible correlation structure among the random intercepts, where the correlations can be interpreted in terms of Kendall's $\tau$. For example, the marginal correlations among the repeated binary outcomes can decline with increasing time separation, while the model retains the property of having matching conditional and marginal logit link functions. Finally, the proposed method is used to analyze data from a longitudinal study designed to monitor cardiac abnormalities in children born to HIV-infected women.
CFD evaluation of thermal convection inside the DACON convection sensor in actual space flight  [PDF]
Pradyumna Ghosh, M. K. Ghosh
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.36057
Abstract: A CFD(Computational Fluid Dynamics) model has been developed using the commercial CFD package FLUENT for the thermal convection inside air filled cylindrical DACON sensor, where the onboard time dependent gravitational micro acceleration has been considered. Time dependent, curve fitted gravitational accelera-tion in x- and y-axes from published data have been incorporated in FLUENT through a User Defined Function (UDF), developed in C which includes space craft rotation. At the sensor plane the two-dimensional flow has also been visualized. A good agreement is between simu-lation and published experimental data. Last but not the least, for checking its response to suffi-ciently strong perturbations in an orbital flight, physical and numerical experiments are carried out where an astronaut swung the sensor in hands along the y axis with amplitude of 10cm and a frequency of 0.2 Hz. A good qualitative validation has been achieved between CFD and actual experimental results.
Studies on Synthesis and Characterization of Magnesia Based Refractory Aggregates Developed from Indian Magnesite  [PDF]
Manas Kamal Haldar, Chandrima Ghosh, Arup Ghosh
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.210001
Abstract:

The present work intends to study the properties of magnesia based refractory aggregates developed from Indian magnesite by changing lime/silica ratio. The material has been sintered in the temperature range of 1550C - 1700C. The sintered samples are characterized in terms of bulk density, apparent porosity, true density, percentage densification, mechanical, thermo-mechanical properties like cold modulus of rupture, hot modulus of rupture and thermal shock resistance and structural properties by XRD. The developed microstructures at different temperatures are studied through FESEM study and compositional analysis of the developed phases is done by EDX study.

A Time Decay Vacuum is a New Era of Space Science with Reference to Magnetohydrodynamic Flows  [PDF]
Swapan Kumar Ghosh
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.13012
Abstract: A controlled thermonuclear fusion reaction of the Sun is the heart of the space craft propulsion system. A band of ultraviolet radiation and X-ray emission of shorter wave length permeated by a magnetic mirror in the presence of a radiofrequency accelerator with the Sun at the resonant level is to produce hydrogen fusion laser due to a driving force to act as a laser fusion thruster. A superfluid helium (4He2) of burning with the Sun is a fifth state of matter. A higher state of matter is confined to a typical helical line which corresponds to the existence of outer universe.
Pancreatic Body Fracture does not Necessarily Imply Loss of Ductal Integrity Following Blunt Trauma Abdomen—A Rare Image  [PDF]
Disha Syal, Arindam Ghosh
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.25054
Abstract: Pancreatic injuries can result in significant morbidity and mortality if missed or unnoticed and also pose a great challenge in terms of diagnosis and treatment. We present a case of an 11 year old boy presenting with history of blunt trauma abdomen following handle bar injury. He had signs of abdominal distension and CECT of the abdomen showed transection of the pancreas in the region of junction between the body and tail. On exploratory laparotomy there was rupture at junction of body and tail of pancreas with intact pancreatic duct and a spleen preserving distal pancreatectomy was performed. In the presence of an intact pancreatic duct conservative management should be offered however this patient underwent spleen preserving distal pancreatectomy because of pancreatitis and necrosis ensuing in the pancreatic remnant margin. Hence, complete transection does not necessarily mean loss of ductal integrity and decision to preserve or remove the distal pancreas should not be based merely on ductal integrity but probably other factors also i.e. pancreatitis and necrosis.
Asymmetric Variation in Soil Carbon Emission in Sub-Tropics  [PDF]
Rashmi Kant, Chirashree Ghosh
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.21012
Abstract: Carbon dioxide emission from soil, known as soil respiration, is one of the major sources of the atmospheric carbon. Understanding the relationship between emission rate and the factors associated with the emission process is important in global carbon emission management. The present study investigated soil respiration at three ecologically diverse locations in northern India. CO2 emission was measured in-situ by modified alkali absorption method at three different depths, top-soil (0 cm - 2 cm depth), mid-soil (20 cm depth) and deep-soil (40 cm depth) at each location. Rate of carbon emission from soil varied with location and time. The rate was higher at Riverine Zone (RZ) which had high soil moisture content and profuse ground vegetation compared to Hilly Zone (HZ) containing dry soil and scarce vegetation. The emission rate was also greater in grassland than the plantation area. Rate of carbon emission from soil was heterogeneous along different depths below the ground. Diel variation in emission rate was greater at HZ compared to RZ. Higher microbial population in soil was detected in RZ than HZ. However, the bacterial count out-numbered the fungal count in soils at most places. The study indicates a positive relationship between soil respiration rate and microbial abundance. The fungal population was strongly correlated with CO2 emission rate.
Design Consideration in the Development of Multi-Fin FETs for RF Applications  [PDF]
Peijie Feng, Prasanta Ghosh
World Journal of Nano Science and Engineering (WJNSE) , 2012, DOI: 10.4236/wjnse.2012.22011
Abstract: In this paper, we propose multi-fin FET design techniques targeted for RF applications. Overlap and underlap design configuration in a base FinFET are compared first and then multi-fin device (consisting of transistor unit up to 50) is studied to develop design limitations and to evaluate their effects on the device performance. We have also investigated the impact of the number of fins (up to 50) in multi-fin structure and resulting RF parameters. Our results show that as the number of fin increases, underlap design compromises RF performance and short channel effects. The results provide technical understanding that is necessary to realize new opportunities for RF and analog mixed-signal design with nanoscale FinFETs.
Encapsulation of PCM for Thermo-Regulating Fabric Application  [PDF]
Subhas Ghosh, Prasad Bhatkhande
International Journal of Organic Chemistry (IJOC) , 2012, DOI: 10.4236/ijoc.2012.24050
Abstract: Polyethylene glycol (PEG) has been used as a phase change material (PCM) to create a thermo-regulating fabric. PEG-600 (Mw) was encapsulated using an in-situ polymerization technique in an oil-in water emulsion with encapsulating water-immiscible liquid by the reaction of urea with formaldehyde at acidic pH. Both FTIR analysis and DSC studies verified the formation of PEG microcapsules (MC). Melting temperature (Tm) of the microcapsules was found approximately 21°C which was the same as neat PEG. The heat storage capacity of these MCs was determined to be 12.78 J/g by DSC analysis. FTIR analysis of the MCs exhibited the peaks at 3211 cm﹣1, 1650 cm﹣1, and 1400 cm﹣1. These are the characteristic absorption peaks of -NH2, -C=O stretching and -CH bending vibrations, respectively. Fabric coated with PEG microcapsules showed a 20% higher thermal resistance, than the uncoated fabric, when heated on a Sweating Hot Plate (MTNW Corporation).
Gold Nanoparticles: Acceptors for Efficient Energy Transfer from the Photoexcited Fluorophores  [PDF]
Debanjana Ghosh, Nitin Chattopadhyay
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.31004
Abstract:

The citrate reduction method of synthesis of gold nanoparticles (AuNP) is standardized with the assistance of instruments like spectrophotometer and TEM. A correlation has been developed between the particle diameter and the fractional concentration of the reductant. This enables one to assess the diameter of the AuNP to be synthesized, in advance, from the composition of the reaction mixture and the diameter of the synthesized particles can be confirmed simply from spectrophotometry. Further, it has been demonstrated that the synthesized AuNPs serve as excellent acceptors for a super-efficient energy transfer (ET) from the donor coumarin 153, leading to a quenching of fluorescence of the latter. The Stern-Volmer constants determined from the fluorescence lifetimes are in the range 107 - 109 mol-1·dm3 and are orders of magnitude higher than the normal photochemical quenching processes. The energy transfer efficiency increases radically with an increase in the size of the metal nanoparticle. The highly efficient energy transfer and the variation of the efficiency of the ET process with a variation of the particle size is ascribed to a large enhancement in the extinction coefficient and an increase in the spectral overlap between the plasmon absorption band of AuNPs and the fluorescence spectrum of C153 with an increase in the size of the nanoparticles. The impact of the work remains in providing a demonstration of a super quenching effect of the AuNPs and projects that they can be exploited for developing biosensors with high degree of sensitivity, if tagged to the biomacromolecules.

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