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137 results

Page 1 of 7

  • P.109 Machine learning based approach to improving the prediction of neurological deterioration in mild Degenerative Cervical Myelopathy

  • A Al-Shawwa, M Craig, K Ost, S Tripathy, D Cadotte
  • Journal:
    Canadian Journal of Neurological Sciences / Volume 51 / Issue s1 / June 2024
    Published online by Cambridge University Press:
    24 May 2024, p. S46
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  • Background: Degenerative cervical myelopathy (DCM) is the most common form of atraumatic spinal cord injury globally, yet clinical guidelines remain unclear on surgical recommendations for patients with mild forms of DCM. This is in part due to limitations in current MR imaging interpretation and complex mechanisms of neurological deterioration. Supervised machine learning (ML) models can help to identify clinical and imaging indicators of deterioration within mild DCM patients. Methods: 127 MRI scans (T2w, Diffusion Tensor Imaging, and Magnetization transfer scans) accompanied by a series of clinical tests underwent a semi-automated analysis to derive quantitative metrics. Random forest classifier, Support Vector Machine, and Logistic Regression models were trained and tested to predict 6-month neurological deterioration within patients. Results: The ML models performed, on average, better than previous studies with a balanced accuracy ranging between 70-75%. “Advanced” imaging metrics such as diffusion tensor imaging and magnetization transfer scans played an important role in improving model accuracy but only when used near the maximally compressed disc level, suggesting that limited yet targetted imaging metrics support ML model performance. Conclusions: The inclusion of specific, targeted imaging and clinical metrics support ML model performance in predicting neurological deterioration within mild DCM patients.

  • Evaluation of phenological development and agronomic traits in exotic common bean germplasm across multiple environments

  • T. Basavaraja, Anupam Tripathi, Rahul Chandora, Aditya Pratap, L. Manjuanatha, S. Gurumurthy, Mohar Singh, J. C. Rana, S. D. Nitesh Kumar, P. K. Katiyar, Bansa Singh
  • Journal:
    Plant Genetic Resources / Volume 21 / Issue 3 / June 2023
    Published online by Cambridge University Press:
    29 August 2023, pp. 195-203
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  • Twenty-nine exotic common bean germplasms and three elite cultivars were examined for phenotypic diversity in two bean-producing environments (Kanpur and Shimla) across three winter seasons and one rainy season. The estimate of genetic variability parameters revealed that the exotic bean germplasm has enough diversity for all the evaluated features. The highest genotypic and phenotypic coefficients of variation were found in seed yield, followed by 100-seed weight, pods per plant and pod length. Furthermore, seed yield was the most heritable and genetically advanced quantitative feature, followed by 100-seed weight, pod length and pods per plant. According to a trait association study, the days to maturity of phenological traits have a strong positive correlation with the days to initial flowering and the days to 50% flowering. Pods per plant and seeds per pod most strongly influence increased grain yield. The first two principal components accounted for 63.3% of the variation and demonstrated significant diversity among exotic bean lines for the traits studied, according to the principal component analysis. According to the hierarchical clustering analysis, 29 accessions and three cultivars were divided into three groups. Cluster I contains early flowering and maturing accessions, while cluster III contains high pods per plant and an increased grain yield of germplasms. The fundamental source of phenological fluctuations in both environmental circumstances is temperature. This study found four genetically divergent and stable performance accessions, including EC932021, EC932189 (earliness), and EC931452, EC931971 (high grain yield), which may aid in the establishment of a bean breeding programme.

  • Perceived stigma, self stigma and barriers to treatment in alcohol dependent individuals

  • R. Tripathi, S. Singh, M. Prithviraj, A. Nair
  • Journal:
    European Psychiatry / Volume 66 / Issue S1 / March 2023
    Published online by Cambridge University Press:
    19 July 2023, p. S673
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  • Introduction

    Alcohol use disorder is a chronic relapsing disorder. It is a matter of global health concern affecting different countries, cultures, economic classes and ethnic groups. Although, many people benefit from alcohol related treatment, low occurrence of treatment seeking is a common denominator for the majority of people suffering from alcohol use disorder.

    Objectives

    The aim of the present study was to study barriers of treatment seeking and assess self and perceived stigma in alcohol dependent male patients in rural population of India

    Methods

    An observational study was conducted at a private de-addiction center in India. Male patients who were more than 18 years old, alcohol dependent with more than seven days of admission (not currently in withdrawal) were included in the study

    Results

    The mean age of the sample was 29.1 (7.8) years and age of onset of alcohol use was 18.5 (3.3) years. The mean quantity of alcohol used per day was around 550 millilitres of IMFL per day. The mean number of previous abstinent attempt were two. The most common barrier to treatment was financial (poor affordability). Not serious enough to change and being afraid of what others might think (stigma) were other common barriers. The mean value of perceived stigma was 21.9 (2.3). No co-relation was observed between stigma (both perceived and self stigma) and age of onset and quantity of alcohol consumed

    Conclusions

    These barriers and stigma needs to be addressed to improve treatment seeking and reduce relapse in our population

    Disclosure of Interest

    None Declared

  • Low dose Amantadine and Escitalopram combination in Atypical Parkinsonian disorders- A Retrospective chart review

  • S. M. Tripathi, P. Chutia
  • Journal:
    European Psychiatry / Volume 66 / Issue S1 / March 2023
    Published online by Cambridge University Press:
    19 July 2023, pp. S235-S236
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  • Introduction

    The response to conventional antiparkinsonian medications is elusive in atypical parkinsonian disorders. Improvement in parkinsonian symptoms in atypical parkinsonian disorders has been reported with anecdotal use of Amantadine. The role of serotonergic control over the nigrostriatal pathway led to the use of Escitalopram.

    Objectives

    To examine the efficacy of low dose Amantadine and Escitalopram combination treatment in atypical parkinsonian disorder

    Methods

    A retrospective chart review of Atypical Parkinsonian disorder patients who received the combination of low dose Amantadine and Escitalopram and had follow up assessment available for a minimum of four months were studied. The primary outcome measure was change in Progressive Supranuclear Palsy rating scale, Unified Multiple System Atrophy rating scale score and Clinical Global Improvement Scale Change score in follow up visits.

    Results

    A total of 8 patients with a mean age of 68.5 years, 6 with a diagnosis of Progressive Supranuclear Palsy(PSP) and 2 with a diagnosis of Multiple System Atrophy(MSA) met the selection criteria for the study. Patients were treated with the dose of Amantadine 50mg twice daily and Escitalopram 5mg once daily. The symptom domain to respond first was autonomic symptoms followed by gait, mentation, limb and bulbar symptoms. Amantadine has unique dopaminergic and NMDA antagonist properties. Serotonin has a role in modulation of the autonomic functions and nigrostriatal circuitry. Thus, combining Escitalopram with Amantadine can help ameliorate the array of symptoms in atypical parkinsonian disorders.

    Conclusions

    The PSP and MSA patients responded to the combination of low dose Amantadine and Escitalopram as evidenced by objective rating scales and subjective clinician assessment. Further prospective trials for longer duration are needed to establish the effect size and stability of response.

    KEYWORDS: steele richardson olszewski disease, shy dragger syndrome, antidepressants

    Disclosure of Interest

    None Declared

  • Vascular risk factors affect different brain regions in people with Alzheimer’s disease

  • S. Tripathi, A. Murray, C. Wischik, B. Schelter
  • Journal:
    European Psychiatry / Volume 65 / Issue S1 / June 2022
    Published online by Cambridge University Press:
    01 September 2022, pp. S334-S335
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  • Introduction

    Vascular risk factors including hypertension, diabetes and dyslipidaemia promote diverse pathological mechanisms in the brain leading to cerebral hypoperfusion and ultimately cognitive decline in people. Medial temporal, medial frontal and anterior cingulate atrophy has been closely associated with diabetes and medial temporal lobe atrophy is associated with hypertension in people with Alzheimer’s disease (AD).

    Objectives

    To assess if hypertension, diabetes and dyslipidaemia have differential effects on different brain locations using brain imaging in people with AD.

    Methods

    The current study is based on [18F] fluorodeoxyglucose- positron emission tomography (FDG-PET) data of 970 participants from two large Phase III multi-centre clinical trials of a novel tau aggregation inhibitor drug Leuco-Methylthioninium (LMTX)meeting research criteria for mild to moderate AD. Vascular risk factor data including hypertension, diabetes and dyslipidaemia were collected and quantification of FDG PET hypo-metabolism was done by calculating Standardized Uptake Value Ratio(SUVR).

    Results

    Hypertension, diabetes and dyslipidaemia were found to have differential effects on brain locations in people with AD. When people with hypertension, diabetes and dyslipidaemia were compared to those without, mean SUVR was increased significantly in both left and right parietal and occipital lobes and decreased in left and right anterior cingulate gyri in hypertensives. SUVR was significantly higher in both left and right temporal lobes in diabetics andlower in both left and right anterior cingulate gyri in people with dyslipidaemia.

    Conclusions

    Vascular risk factors including hypertension, diabetes and dyslipidaemia have differential effects on different brain regions, measured using SUVR analysis of FDG-PET.

    Disclosure

    The FDG-PET data was taken from participants of two large phase III clinical trials sponsored by TauRx Therapeutics (Singapore). TauRx Therapeutics has contributed towards my studentship during my PhD but the data related to drug used in the clinical tria

  • Efficacy of middle-ear packing in success of type 1 tympanoplasty: a prospective randomised study

  • S R Sahoo, J Tripathi, S Kumari, S Rastogi
  • Journal:
    The Journal of Laryngology & Otology / Volume 135 / Issue 10 / October 2021
    Published online by Cambridge University Press:
    26 July 2021, pp. 864-868
    Print publication:
    October 2021
  • Objective

    A prospective randomised study was undertaken to compare the results of type 1 tympanoplasty with and without middle-ear packing with gelfoam.

    Method

    Eighty patients undergoing type 1 tympanoplasty were randomised into two groups according to packing in the middle ear: with gelfoam and without gelfoam. The data in terms of graft uptake rate, hearing gain and subjective improvement were analysed at one and three months.

    Results

    The graft uptake rate between both groups did not show a statistically significant difference. There was conductive hearing loss in the gelfoam group in the early post-operative period. Subjectively, patients were more comfortable with respect to heaviness and hearing gain than in the non-gelfoam group.

    Conclusion

    Gelfoam use in middle-ear packing is not an essential step and causes more discomfort in patients during the early post-operative period. It should be a surgeon's choice to use it when and where it is necessary.

  • Evaluation of diverse germplasm of cowpea [Vigna unguiculata (L.) Walp.] against bruchid [Callosobruchus maculatus (Fab.)] and correlation with physical and biochemical parameters of seed

  • Kuldeep Tripathi, T. V. Prasad, R. Bhardwaj, S. K. Jha, D. P. Semwal, P. G. Gore, P. K. Sharma, S. Bhalla
  • Journal:
    Plant Genetic Resources / Volume 18 / Issue 3 / June 2020
    Published online by Cambridge University Press:
    27 July 2020, pp. 120-129

  • The current study was undertaken to identify the sources of tolerance to bruchid in cowpea, by screening a set of germplasm accessions as a source for natural resistance. A total of 103 diverse accessions of cowpea were evaluated for resistance to Callosobruchus maculatus Fab. under no-choice artificial infestation conditions. Significant differences among the cowpea accessions were observed for oviposition, adult emergence, exit holes and per cent seed weight loss (PSWL) caused by the bruchid infestation. The accessions showed variation in physical seed parameters viz., colour, shape, testa texture, length, width and seed hardness. Among the seed biochemical parameters studied, per cent sugar content ranged from 0.322 (IC330950) to 1.493 (IC249137), and per cent phenol content ranged from 0.0326 (EC390261) to 1.081 (EC528423). Correlation studies indicated that PSWL had significant positive correlation (r = 0.335) with exit holes, oviposition (r = 0.219), adult emergence (r = 0.534) and seed roundness (r = 0.219). Adult emergence had a significant negative correlation with seed hardness (r = −0.332). Correlation with biochemical parameters indicated that PSWL had a significant positive correlation (r = 0.231) with sugar content and a significant negative correlation with phenol content (r = −0.219). None of the accessions were found to be immune to bruchid infestation. However, out of studied accessions, EC528425 and EC528387 were identified as resistant based on PSWL and moderately resistant based on adult emergence. These resistance sources of cowpea germplasm can be used as potential donors for development of bruchid tolerant/resistant cultivars.

  • 13 - Vlasov and Particle-in-Cell Simulations

  • C. S. Liu, University of Maryland, College Park, V. K. Tripathi, Indian Institute of Technology, Delhi, Bengt Eliasson, University of Strathclyde
  • Book:
    High-Power Laser-Plasma Interaction
    Published online:
    26 April 2019
    Print publication:
    16 May 2019, pp 263-274

  • Summary

    Introduction

    Particle-in-cell (PIC) and Vlasov simulations both solve the Vlasov equation. The Vlasov equation (cf. Chapter 2) governs the evolution of the distribution function of charged particles (electrons, ions) in the six-dimensional phase space, consisting of three velocity (or momentum) dimensions and three position dimensions, plus time. It offers an accurate description of a plasma in the collisionless limit; that is, when the particles are affected by long-range electric and magnetic fields only, and when short-range fields from their nearest neighbors can be neglected.

    PIC simulations resolve the distribution function statistically with macro-particles (or super-particles) and follows the solution over trajectories along which the distribution function is constant; the characteristics are given by the equations of motion for the charged particles. This is the Lagrangian description. Many PIC codes have been developed over the years; modern PIC codes include the plasma simulation code (PSC) originally developed by Hartmut Ruhl, the implicit iPIC3D code aimed at connecting kinetic and magnetohydrodynamic time scales, the EPOCH code, partially based on PSC, the VSIM/VORPAL code, the OSIRIS code, and QuickPIC. PIC simulations are very adaptive and efficient for many problems, such as high-energy beam–plasma and laser–plasma interactions. On the other hand, they also have limitations; the numerical noise and slow convergence with increasing number of particles are some issues. There is also the need to resolve the Debye length with particles to avoid artificial numerical heating.

    A different strategy is followed in Vlasov simulations using a Eulerian description. Here, the distribution function is treated as a phase fluid resolved on a fixed numerical grid. Vlasov simulations do not have the statistical noise of PIC simulations; they can also more accurately resolve the high-velocity tail of the particle distribution functions. On the other hand, Vlasov simulations in higher dimensions are very memory demanding due to the need to resolve the six-dimensional phase space on a numerical grid. In some cases, the distribution function can also become oscillatory in phase space, leading to sharp gradients and a need to introduce numerical dissipation in velocity space whilst avoiding artificial numerical heating due to the broadening of the distribution in velocity space. Hence, the choice between PIC and Eulerian Vlasov simulations strongly depends on the physical problem at hand.

  • Preface

  • C. S. Liu, University of Maryland, College Park, V. K. Tripathi, Indian Institute of Technology, Delhi, Bengt Eliasson, University of Strathclyde
  • Book:
    High-Power Laser-Plasma Interaction
    Published online:
    26 April 2019
    Print publication:
    16 May 2019, pp xix-xx

  • Summary

    The laser, with its coherent, monochromatic, and well collimated character, has been a most remarkable discovery of the twentieth century. Along with semiconductors, its multifaceted applications have broadly touched and greatly improved our lives – it has made an indelible mark in the field of sensing, printing, barcode scanning, surgery, communications, and so on. It has also become a major tool for scientific research. For example, Thomson scattering and laser induced fluorescence are important tools for plasma diagnostics. Lasers have been used successfully for cooling of atoms and heating of plasmas.

    The laser peak power has increased about a 1000 fold every decade since its invention. Starting from hundred watts in the 1960s, table top terawatt Ti: sapphire lasers became available in the 1990s following the discovery of the chirped pulse amplification (CPA) by Mourou and Strickland in 1985. These lasers do not only have high power but also very short pulses of a few femtoseconds, opening a new field of ultra-short pulse lasers and their interactions with matter, such as electron dynamics in molecules. In the past few years, we have seen worldwide efforts to build high power laser infrastructures. The Extreme Light Infrastructure (ELI) has been approved to construct three petawat laser facilities in Eastern Europe. Similar efforts are being made in Korea, Japan and China.

    With the rise in laser power, there has been a phenomenal growth in the field of high power laser-plasma interaction with diverse applications, ranging from laser driven fusion and laser acceleration of charged particles to laser ablation of materials. The field has revealed a rich variety of fascinating new phenomena. Parametric coupling between lasers and plasma eigenmodes and quasi-modes gives rise to stimulated Raman, Brillouin, and Compton scattering, two-plasmon decay, and four-wave processes of filamentation, modulational, and oscillating two-stream instabilities of the laser. Nonlinear refraction gives rise to selffocusing and self-guiding of lasers over long distances in plasma and air, offsetting diffraction divergence. Laser interaction with rough metallic surfaces reveals surface-enhanced Raman scattering (SERS) where Raman scattered power from adsorbed molecules rises a million times due to surface plasmon resonance. Laser mode conversion to surface plasma waves (SPWs) on metallic surfaces has been shown to enhance the ablation yield and thin film deposition rates by orders of magnitude, making pulsed laser deposition a very attractive scheme.

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