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Chinese Physics B 2015年第10期24卷 604-611页

作者： Gopi Krishna Saramekala Sarvesh Dubey pramod kumar tiwari Department of Electronics and Communication Engineering National Institute of Technology Shri Ramswaroop Memorial University

In this paper, a surface potential based threshold voltage model of fully-depleted（FD） recessed-source/drain（Re-S/D）silicon-on-insulator（SOI） metal-oxide semiconductor field-effect transistor（MOSFET） is presented while considering the effects of high-k gate-dielectric material induced fringing-field. The two-dimensional（2D） Poisson＇s equation is solved in a channel region in order to obtain the surface potential under the assumption of the parabolic potential profile in the transverse direction of the channel with appropriate boundary conditions. The accuracy of the model is verified by comparing the model＇s results with the 2D simulation results from ATLAS over a wide range of channel lengths and other parameters,including the dielectric constant of gate-dielectric material.

关键词： recessed-source/drain （Re-S/D） high-k gate-material fringing field and SCEs

On-current modeling of short-channel double-gate(DG) MOSFETs with a vertical Gaussian-like doping profile

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Journal of Semiconductors 2013年第5期34卷 46-53页

作者： Sarvesh Dubey pramod kumar tiwari S.Jit Department of Electronics Engineering Indian Institute of Technology(BHU)Varanasi-221005India Department of Electronics and Communication Engineering National Institute of Technology Rourkela-769008India

An analytic drain current model is presented for doped short-channel double-gate MOSFETs with a Gaussian-like doping profile in the vertical direction of the channel. The present model is valid in linear and satura- tion regions of device operation. The drain current variation with various device parameters has been demonstrated. The model is made more physical by incorporating the channel length modulation effect. Parameters like transcon- ductance and drain conductance that are important in assessing the analog performance of the device have also been formulated. The model results are validated by numerical simulation results obtained by using the commercially available ATLAS^TM, a two dimensional device simulator from SILVACO.

关键词： drain current DG MOSFET transconductance drain conductance

Analytical model for subthreshold current and subthreshold swing of short-channel double-material-gate MOSFETs with strained-silicon channel on silicon–germanium substrates

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Journal of Semiconductors 2014年第10期35卷 30-36页

作者： pramod kumar tiwari Gopi Krishna Saramekala Sarvesh Dubey Anand kumar Mukhopadhyay National Institute of Technology Rourkela Department of Electronics and Communication Engineering Faculty of Electronics and Communication SRM University

The present work gives some insight into the subthreshold behaviour of short-channel double-material- gate strained-silicon on silicon-germanium MOSFETs in terms of subthreshold swing and off-current. The formu- lation of subthreshold current and, thereupon, the subthreshold swing have been done by exploiting the expression of potential distribution in the channel region of the device. The dependence of the subthreshold characteristics on the device parameters, such as Ge mole fraction, gate length ratio, work function of control gate metal and gate length, has been tested in detail. The analytical models have been validated by the numerical simulation results that were obtained from the device simulation software ATLASTM by Silvaco Inc.

关键词： strained-Si channel Si1-xGex substrate dual-metal gate subthreshold current subthreshold swing

Analog and radio-frequency performance analysis of silicon-nanotube MOSFETs

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Journal of Semiconductors 2016年第6期37卷 60-63页

作者： pramod kumar tiwari mukesh kumar ramavathu sakru naik gopi krishna saramekala Department of Electronics and Communication Engineering National Institute of TechnologyRourkela-769008OdishaIndia

This work presents a comparative study of the influence of various parameters on the analog and RF properties of silicon-nanotube MOSFETs and nanowire-based gate-all-around（GAA） MOSFETs.The important analog and RF performance parameters of SiNT FETs and GAA MOSFETs,namely drain current（/d）,transconductance to drain current ratio（g_m/I_d）,I_（on）/I_（off）,the cut-off frequency（f_T） and the maximum frequency of oscillation（/max） are evaluated with the help of Y- and H-parameters which are obtained from a 3-D device simulator,ATLAS^（TM）.It is found that the silicon-nanotube MOSFETs have far more superior analog and RF characteristics（g_m/I_d,f_T and /max） compared to the nanowire-based gate-all-around GAA MOSFETs.The silicon-nanotube MOSFET shows an improvement of ~2.5 and 3 times in the case of f_T and /max values respectively compared with the nanowire-based gate-all-around（GAA） MOSFET.

关键词： analog and RF SiNT MOSFETs GAA MOSFETs unity gain frequency unity power frequency

A Bayesian multi-model inference methodology for imprecise momentindependent global sensitivity analysis of rock structures

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 840-859页

作者： Akshay kumar Gaurav tiwari Department of Civil Engineering Indian Institute of Technology(IIT)KanpurKanpur208016India

Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(i.***.type of distribution type and its parameters)of input rock properties emanating due to the small size of datasets while mapping the relative importance of properties to the model response.This paper proposes an augmented Bayesian multi-model inference(BMMI)coupled with GSA methodology(BMMI-GSA)to address this issue by estimating the imprecision in the momentindependent sensitivity indices of rock structures arising from the small size of input data.The methodology employs BMMI to quantify the epistemic uncertainties associated with model type and parameters of input properties.The estimated uncertainties are propagated in estimating imprecision in moment-independent Borgonovo’s indices by employing a reweighting approach on candidate probabilistic models.The proposed methodology is showcased for a rock slope prone to stress-controlled failure in the Himalayan region of India.The proposed methodology was superior to the conventional GSA(neglects all epistemic uncertainties)and Bayesian coupled GSA(B-GSA)(neglects model uncertainty)due to its capability to incorporate the uncertainties in both model type and parameters of properties.Imprecise Borgonovo’s indices estimated via proposed methodology provide the confidence intervals of the sensitivity indices instead of their fixed-point estimates,which makes the user more informed in the data collection efforts.Analyses performed with the varying sample sizes suggested that the uncertainties in sensitivity indices reduce significantly with the increasing sample sizes.The accurate importance ranking of properties was only possible via samples of large sizes.Further,the impact of the prior knowledge in terms of prior ranges and distributions was significant;hence,any related assumption should be made carefully.

关键词： Bayesian inference Multi-model inference Statistical uncertainty Global sensitivity analysis(GSA) Borgonovo’s indices Limited data

Tubularized incised plateurethroplasty and grafted tubularized incised plate urethroplasty: systematic review, metaanalysis and trial sequential analysis

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World Journal of Pediatric Surgery 2024年第1期7卷 10-19页

作者： Nitinkumar Borkar Charu tiwari Abhijit Nair Debajyoti Mohanty C K Sinha Jai kumar Mahajan Paediatric Surgery All India Institute of Medical Sciences-RaipurRaipurChhattisgardhIndia Department of Anaesthesiology Ibra HospitalbraOman General Surgery All India Institute of Medical Sciences-RaipurRaipurChhattisgardhIndia Paediatric Surgery St George's University Hospitals NHS Foundation TrustLondonUK Pediatric Surgery PGIMERChandigarhIndia

Background Hypospadias is one of the most common genital birth defects.There are around 300 various techniques available for the repair of hypospadias.This study aims to compare the reported outcomes of Tubularized incised plate urethroplasty(TIP)and Grafted TIP(GTIP)repair in children undergoing primary hypospadiasrepair.Methods This meta-analysisadhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines,and we framed our research question using the population,intervention,control and outcomes format.We conducted comprehensive electronic searches across various databases,employing a Boolean search strategy with predefined search terms.Only randomized controlled trials(RCTs)were included for quantitative analysis.Results Totally,10 RCTs met our inclusion criteria for quantitative analysis.The results indicated that urethrocutaneous fistula,glans dehiscence,and stricture rates were comparable between the two groups.The incidence of meatal stenosis was found to be significantly lower in the GTIP group with a relative risk(RR)of 0.32(95%confidence interval(Cl)0.15 to 0.67).Conclusion The coucomes UCF,glans dehiscence,and stricture rates were comparable between the two groups.Notably,the incidence of meatal stenosis was found to be significantly lower in the grafted TIP group.In terms of operative time,our quantitative synthesis demonstrated that the TIP group had a shorter operative time than the GTIP group with significant heterogeneity.

关键词： plate grafted analysis

Role of fecal microbiota transplant in management of hepatic encephalopathy: Current trends and future directions

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World Journal of Hepatology 2024年第1期16卷 17-32页

作者： Yash R Shah Hassam Ali Angad tiwari David Guevara-Lazo Natalia Nombera-Aznaran Bhanu Siva Mohan Pinnam Manesh kumar Gangwani Harishankar Gopakumar Amir H Sohail SriLakshmiDevi Kanumilli Ernesto Calderon-Martinez Geetha Krishnamoorthy Nimish Thakral Dushyant Singh Dahiya Department of Internal Medicine Trinity Health Oakland/Wayne State UniversityPontiacMI 48341United States Division of Gastroenterology and Hepatology East Carolina University/Brody School of MedicineGreenvilleNC 27858United States Department of Internal Medicine Maharani Laxmi Bai Medical CollegeJhansi 284001India Faculty of Medicine Universidad Peruana Cayetano HerediaLima 15102Peru Department of Internal Medicine John H.Stroger Hospital of Cook CountyChicagoIL 60612United States Department of Internal Medicine The University of ToledoToledoOH 43606United States Department of Gastroenterology and Hepatology University of Illinois College of Medicine at PeoriaPeoriaIL 61605United States Department of Surgery University of New MexicoAlbuquerqueNM 87106United States Department of Internal Medicine GSL Medical CollegeRajamahendravaram 533296India Department of Internal Medicine Universidad Nacional Autonoma de MexicoCiudad De Mexico 04510Mexico Department of Digestive Diseases and Nutrition University of KentuckyLexingtonKY 40536United States Division of Gastroenterology Hepatology&MotilityThe University of Kansas School of MedicineKansas CityKS 66160United States

Fecal microbiota transplantation(FMT)offers a potential treatment avenue for hepatic encephalopathy(HE)by leveraging beneficial bacterial displacement to restore a balanced gut microbiome.The prevalence of HE varies with liver disease severity and comorbidities.HE pathogenesis involves ammonia toxicity,gut-brain communication disruption,and inflammation.FMT aims to restore gut microbiota balance,addressing these factors.FMT's efficacy has been explored in various conditions,including HE.Studies suggest that FMT can modulate gut microbiota,reduce ammonia levels,and alleviate inflammation.FMT has shown promise in alcohol-associated,hepatitis B and C-associated,and non-alcoholic fatty liver disease.Benefits include improved liver function,cognitive function,and the slowing of disease progression.However,larger,controlled studies are needed to validate its effectiveness in these contexts.Studies have shown cognitive improvements through FMT,with potential benefits in cirrhotic patients.Notably,trials have demonstrated reduced serious adverse events and cognitive enhancements in FMT arms compared to the standard of care.Although evidence is promising,challenges remain:Limited patient numbers,varied dosages,administration routes,and donor profiles.Further large-scale,controlled trials are essential to establish standardized guidelines and ensure FMT's clinical applications and efficacy.While FMT holds potential for HE management,ongoing research is needed to address these challenges,optimize protocols,and expand its availability as a therapeutic option for diverse hepatic conditions.

关键词： Hepatic encephalopathy Fecal microbiota transplant Cognitive impairment Liver cirrhosis Chronic liver disease

Some Features of Black Carbon Aerosols Connected with Regional Climate Over Pristine Environment

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Journal of Atmospheric Science Research 2024年第1期7卷 1-18页

作者： Saurabh Yadav Panuganti C.S.Devara S.M.Sonbawne B.S.Murthy S.tiwari S.Wadhwa A.kumar Amity Centre of Excellence in Ocean-Atmosphere Science and Technology(ACOAST) Amity University Haryana(AUH)Gurugram122413India Indian Institute of Tropical Meteorology(IITM) PashanPune411008India

The authors report the results of aethalometer black carbon(BC)aerosol measurements carried out over a rural(pristine)site,Panchgaon,Haryana State,India during the winter months of 2021-2022 and 2022-2023.They are compared with collocated and concurrent observations from the Air Quality Monitoring Station(AQMS),which provides synchronous air pollution and surface meteorological parameters.Secular variations in BC mass concentration are studied and explained with variations in local meteorological parameters.The biomass burning fire count retrievals from NASA-NOAA VIIRS satellite,and backward airmass trajectories from NOAA-ERL HYSPLIT Model analysis have also been utilized to explain the findings.They reveal that the north-west Indian region contributes maximum to the BC mass concentration over the study site during the study period.Moreover,the observed BC mass concentrations corroborate the synchronous fire count,primary and secondary pollutant concentrations.The results were found to aid the development of mitigation methods to achieve a sustainable climate system.

关键词： Carbonaceous aerosols Dual-spot technique Temporal variations Primary and secondary pollutants Stubble burning Long-range transport Satellite products

Implications of Elevated Serum Cortisol in the Onset of Postoperative Delirium Following Off-Pump Coronary Artery Bypass Grafting: Insights from a Bangladesh-Based Single Center Experience

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World Journal of Cardiovascular Diseases 2024年第4期14卷 252-267页

作者： Vivek kumar Jha Md Abir Tazim Chowdhury Munama Magdum Manoj tiwari Md Abul Bashar Maruf Md Saiful Islam Khan Priyanka Sinha Rajesh Naryan Kapar Md. Rezwanul Hoque Department of Cardiothoracic and Vascular Surgery BP Koirala Institute of Health Sciences Dharan Nepal Department of Cardiothoracic and Vascular Surgery Evercare Hospital Dhaka Dhaka Bangladesh Department of Preventive and Social Medicine National Institute of Preventive and Social Medicine Dhaka Bangladesh Department of Thoracic Surgery BP Koirala Memorial Cancer Hospital Bharatpur Nepal Department of Cardiac Surgery United Hospital Limited Dhaka Bangladesh Department of Cardiothoracic Anesthesia Evercare Hospital Dhaka Dhaka Bangladesh Department of Microbiology Kathmandu Medical College Kathmandu Nepal Department of Nephrology Bangabandhu Sheikh Mujib Medical University Dhaka Bangladesh Department of Cardiac Surgery Bangabandhu Sheikh Mujib Medical University Dhaka Bangladesh

Background: Following coronary artery bypass grafting (CABG), delirium emerges as a prevalent complication. This study aimed to assess the correlation between elevated serum cortisol levels and the occurrence of postoperative delirium subsequent to off-pump CABG. Methods: Conducted in the Department of Cardiac Surgery at BSMMU from October 2020 to September 2022, this comparative cross-sectional study included a total of 44 participants. Subjects, meeting specific criteria, were purposefully assigned to two groups based on off-pump CABG. Group A (n = 22) consisted of patients with normal serum cortisol levels, while Group B (n = 22) comprised individuals with high serum cortisol levels on the first postoperative day. Delirium onset was assessed at the bedside in the ICU on the 1st, 2nd, 3rd, 4th, and 5th postoperative days using standard tools, namely the Richmond Agitation Sedation score (RASS) and The Confusion Assessment Method (CAM-ICU). Data were collected based on the presence or absence of delirium. Statistical analysis utilized SPSS version 26.0, employing an independent Student’s t-test for continuous data and chi-square and Fischer’s exact test for categorical data. A p-value ≤ 0.05 was considered statistically significant. Results: Group-A had a mean age of 54.50 ± 17.97, and Group-B had a mean age of 55.22 ± 15.45, both with a male predominance (81.81% and 86.36% respectively). The mean serum cortisol level was significantly higher in Group B (829.71 ± vs. 389.98 ± 68.77). Postoperative delirium occurred in 27.3% of Group B patients, statistically significant compared to the 4.5% in Group A. However, patients in Group B who developed delirium experienced significantly longer postoperative ICU and hospital stays (79.29 ± 12.27 vs. 11.44 ± 2.85, p ≤ 0.05). There was one mortality in Group B, which was statistically not significant. Conclusion: This study observed a significant association between elevated serum cortisol levels in the postoperative period and the occurrence of postoperative delirium afte

关键词： Coronary Artery Bypass Grafting (CABG) Serum Cortisol Postoperative Delirium Bangladesh

Reliability assessment of deep excavations in spatially random cohesion weakening friction strengthening massive rocks:Application to nuclear repositories

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Underground Space 2023年第6期13卷 48-73页

作者： Akshay kumar Gaurav tiwari Department of Civil Engineering Indian Institute of Technology KanpurKanpurUttar Pradesh 208016India

An augmented methodology is developed to estimate the reliability of deep excavations along spatially variable massive rock masses using the cohesion weakening friction strengthening(CWFS)model.Sensitive parameters of the CWFS model were initially identified using Sobol’s global sensitivity analysis based on their influence on the displacements and excavation damage zone around excavations.The probability of failure was estimated by performing Mont–Carlo Simulations on random finite difference models of excavations generated via MATLAB-FLAC2D coupling,considering the spatial variation of these sensitive parameters.Spatial variation was modeled by generating anisotropic random fields of sensitive CWFS parameters via the recently developed Fourier series method and updated correlations suggested by Walton(2019).The proposed methodology was demonstrated for a proposed deep nuclear waste repository to be located in Canada.Results from the developed methodology were systematically compared with those of traditional reliability(ignoring spatial variation)and deterministic methods(ignoring uncertainty).Although the developed methodology was computationally complex,it was judged to be the most realistic due to the realistic consideration of heterogeneous distributions of rock properties.Traditional methodologies underestimate/overestimate the excavation performance due to negligence of uncertainty and spatial variability.Finally,a parametric analysis was performed using developed methodology by varying the initial friction angle,scale of fluctuations(SOFs)and dilation angle.The effect of initial friction angle was observed to be more pronounced on the probability of failures as compared to SOFs and dilation angle.Similar observations were made related to the excavation damage zone(EDZ)development quantified using yield area ratio.

关键词： Deep excavations Brittle failures CWFS model Sobol’s sensitivity Moving least square response surface Fourier series random field