Papers by Soumya Chakraborty
Econometrics and Statistics
As in other estimation scenarios, likelihood based estimation in the normal mixture setup is high... more As in other estimation scenarios, likelihood based estimation in the normal mixture setup is highly non-robust against model misspecification and presence of outliers (apart from being an ill-posed optimization problem). A robust alternative to the ordinary likelihood approach for this estimation problem is proposed which performs simultaneous estimation and data clustering and leads to subsequent anomaly detection. To invoke robustness, the methodology based on the minimization of the density power divergence (or alternatively, the maximization of the β-likelihood) is utilized under suitable constraints. An iteratively reweighted least squares approach has been followed in order to compute the proposed estimators for the component means (or equivalently cluster centers) and component dispersion matrices which leads to simultaneous data clustering. Some exploratory techniques are also suggested for anomaly detection, a problem of great importance in the domain of statistics and machine learning. The proposed method is validated with simulation studies under different setups ; it performs competitively or better compared to the popular existing methods like K-medoids, TCLUST, trimmed K-means and MCLUST, especially when the mixture components (i.e., the clusters) share regions with significant overlap or outlying clusters exist with small but non-negligible weights (particularly in higher dimensions). Two real datasets are also used to illustrate the performance of the newly proposed method in comparison with others along with an application in image processing. The proposed method detects the clusters with lower misclassification rates and successfully points out the outlying (anomalous) observations from these datasets.
Nanomaterials
Current–voltage characteristics of a quantum dot in double-barrier configuration, as formed in th... more Current–voltage characteristics of a quantum dot in double-barrier configuration, as formed in the nanoscale channel of silicon transistors, were analyzed both experimentally and theoretically. Single electron transistors (SET) made in a SOI-FET configuration using silicon quantum dot as well as phosphorus donor quantum dots were experimentally investigated. These devices exhibited a quantum Coulomb blockade phenomenon along with a detectable effect of variable tunnel barriers. To replicate the experimental results, we developed a generalized formalism for the tunnel-barrier dependent quantum Coulomb blockade by modifying the rate-equation approach. We qualitatively replicate the experimental results with numerical calculation using this formalism for two and three energy levels participated in the tunneling transport. The new formalism supports the features of most of the small-scaled SET devices.
2022 IEEE Silicon Nanoelectronics Workshop (SNW)
Indian Drugs
Azelnidipine is a dihydropyridine used as a calcium channel blocker. The main aim of this study w... more Azelnidipine is a dihydropyridine used as a calcium channel blocker. The main aim of this study was to develop a validated bio-analytical method (as per US-FDA and EMA guidelines) for in vivo pharmacokinetic and bioequivalence study of azelnidipine in human plasma by LC-MS/MS, API-4000. In this method, the drug was ionized in negative mode and gave adequate response because this drug was highly sensitive and had high electron affinity due to the presence of the electron-withdrawing the nitro group in the structure of azelnidipine. The deprotonated precursor ions [M-H]- at mz-1 581.2 and consistent fragment ion selected was mz-1 491.0. For internal standard, the deprotonated precursor ions [M-H]- at mz-1 269.0 (highest peak) was observed in Q1 MS and characteristic product ions or fragment ions found in Q3 MS were at mz-1 169.8. For plasma extraction, the liquid-liquid extraction technique was used. The calibration concentrated points of azelnidipine were 0.15 to 10.00 ng mL-1 includ...
Social Science Research Network, 2022
2019 IEEE Energy Conversion Congress and Exposition (ECCE), 2019
High-Efficiency Light-Fidelity (Li-Fi) transmitter for simultaneous illumination and Visible Ligh... more High-Efficiency Light-Fidelity (Li-Fi) transmitter for simultaneous illumination and Visible Light Communications (VLC) using LED lighting is presented in this work. The proposed transmitter is based on Single Inductor Multiple Output (SIMO) buck converter with two independently controllable outputs or channels, namely lighting channel and communications channel for enabling flicker free illumination without affecting high-speed modulation of LEDs. By this approach, power converter switching frequency is decoupled from modulation frequency of LEDs, thereby optimizing SIMO converter switching frequency for efficiency and the VLC modulator frequency for high speed data transfers. GaN devices are used to realize VLC modulator for high speed modulation to further enhance the efficiency. Light output with high Color Rendering Index (CRI) is achieved by controlling white LEDs as primary illumination source at lighting channel and red color LEDs at communication channel. Simulations and experimental results to validate the proposed transmitter are presented.
The European Physical Journal C, 2021
The present work deals with Cosmological model of a three-form field, minimally coupled to gravit... more The present work deals with Cosmological model of a three-form field, minimally coupled to gravity and interacting with cold dark matter in the background of flat FLRW space-time. By suitable choice of the dimensionless variables, the evolution equations are converted to an autonomous system and cosmological study is done by dynamical system analysis. The critical points are determined and the stability of the (non-hyperbolic) equilibrium points are examined by center manifold Theory. Possible bifurcation scenarios have been examined by the Poincaré index theory to identify possible cosmological phase transition. Also stabilities of the critical points have been analyzed globally using geometric features.
Italian journal of anatomy and embryology, 2018
Good clinicians are expected to demonstrate empathetic behaviour whereby it is necessary for medi... more Good clinicians are expected to demonstrate empathetic behaviour whereby it is necessary for medical students to develop an empathetic attitude during the curriculum. The anatomy classroom is possibly the ideal place to cultivate the sense of empathy among medical students as they deal with the feelings associated with dissecting a human cadaver. Hence we conducted this knowledge, attitude and practice study to assess the empathetic attitude among first-year medical students. A self designed, pretested questionnaire was framed to explore the sense of empathy and the questionnaire was administered among 100 first year MBBS students before the summative assessment and their responses were collected and analyzed. We observed that 55% and 16.3% of the respondents were inclined for adopting a mechanized approach to patient care as they were in favour of investigation oriented diagnosis and medicine based treatment respectively as primary component of medical practice. Only 16.3% and 12.2...
Italian journal of anatomy and embryology = Archivio italiano di anatomia ed embriologia, 2015
The practice of the anatomist himself dissecting the human body and demonstrating the details to ... more The practice of the anatomist himself dissecting the human body and demonstrating the details to the students was prevalent in the European universities during the Renaissance (Ghosh, 2015). The great Paduan anatomist, Andreas Vesalius (1514-1564) was a pioneer in this method of teaching as he displayed his exceptional dissection skills to the students during anatomical sessions (Goodrich, 1982). Later on, accomplished anatomists like Hieronymus Fabricius ab Acquapendente (1533-1619), Johann Vesling (1598-1649), Bernhard Siegfried Albinus (1697-1770), William Hunter (17181783) and many others followed the same tradition while teaching in the dissection lab (Mavrodi et al., 2013). Their efforts were instrumental in human cadaveric dissection achieving the central role in medical training and research in those days. Human cadaveric dissection has been the primary medium of teaching gross anatomy to medical students for centuries, however in recent times teaching anatomy by dissection ...
Cureus, 2021
Purpose: The spleen is a fist-sized largest lymphoid organ located in the left hypochondrium. It ... more Purpose: The spleen is a fist-sized largest lymphoid organ located in the left hypochondrium. It has a unique location, embryological and histological structure that differs significantly from other lymphoid organs. The present work was undertaken to study the microscopic and ultramicroscopic histogenesis patterns of the spleen in relation to gestational age. Methods: The splenic tissue of nine aborted fetuses of various gestational ages was studied. For cytology study, special stains like Masson's trichrome, Periodic Acid-Schiff, and Reticulin were used; immunohistochemical staining was performed with triple antibodies (C-myc, Ki-67, and Ber-H2); and for ultrastructure study, aluminum mounted specimens coated with gold and argon gas were observed under scanning electron microscopy (SEM). Results: Microscopy and immunohistochemistry showed the developmental changes in the spleen from the emergence of the primordium to the end of the embryonic period in all stages of fetogenesis. The spleen primordium of a fetus at the developmental stage of the primary vascular reticulum was seen in the first trimester fetuses. The primordium is comprised mainly of mesenchymal tissue; numerous lymphocytes invading the area surrounding the central artery forming the periarterial lymphoid sheaths (PALS) were seen surrounded by venous sinuses in the early second trimester fetuses. Conclusion: The organizational changes in the reticuloendothelial system and microstructure of the spleen during fetogenesis are very crucial to achieving adult morphology in the future. Histogenesis of the fetal spleen follows a multistep process depending upon the gestational age. Any deviation from normalcy may lead to structural and functional abnormality later in life.
International Journal of Scientific and Research Publications (IJSRP), 2020
E-learning in Anatomy is an improved scalability of educational development in this digital era w... more E-learning in Anatomy is an improved scalability of educational development in this digital era which breaks down geographical and temporal barriers presenting opportunities for learners through availability of authentic information, subject content, skill development procedures. The present study involved a total of 195 MBBS students of 2014-2015 and 2015-2016 batches who answered a close and open questionnaire comprising of 12 questions related to utilization of e-learning tools while learning Anatomy in a collaborative manner. Results revealed that 100% 1 st year MBBS students were aware of the availability of elearning Anatomy tools. 89.8% of 2014-2015 and 92.8% students of 2015-2016 batches utilized these learning tools in addition to traditional class room teaching in Anatomy thus adopting a blended approach for effective learning of Anatomy. 75.5% and 70.1% students of the '14-'15 and '15-'16 batches respectively applied group learning strategies and 73.6% and 70.1% students could utilize e-learning of Anatomy in a collaborative manner. Elearning engines utilized by these students were identified and archived establishing Anatomy department's e-learning bank. Thus it has been observed in this study that e-learning in Anatomy allows blended collaborative discovery learning for better alignment of the subject through use of technology, information, communication and networking.
Investigación en Educación Médica, 2018
Introduction: Body donation has emerged as the preferred source of human cadavers around the worl... more Introduction: Body donation has emerged as the preferred source of human cadavers around the world for anatomical education as medical schools around the world are emphasizing on the ethical acquisition of human cadavers because a neo-model of anatomical education is evolving around the world. In some countries, there is a disinterested gift of a human body, for the benefit of medical education and society. In contrast, there are countries, like India, where cadaver donation programs have a lot of problems and medical schools continue to use unclaimed corpses for anatomical studies, raising ethical concerns. Objective: The present study was undertaken to unearth the factors prevalent in the Indian society that adversely affects the health of body bequest programs in the country. Method: A study was conducted based on a questionnaire that included a representative sample of first year medical students Results: Although it was noted that 74.5% respondents were aware of the shortage of human bodies for teaching anatomy in Indian medical schools and 52% responded in favour of donating their bodies in the future, however, just 6.1% of their relatives had made the same decision. Conclusions: The analysis of study observations helped to identify specific factors that adversely affect the outcome of organ donation programs in the country and the authors made some recommendations to improve the scenario. The religious perception of this reality, in a medical education scenario, should be considered.
National Journal of Clinical Anatomy, 2015
In this rare case, found during routine dissection of head and neck in North Bengal Medical Colle... more In this rare case, found during routine dissection of head and neck in North Bengal Medical College on the right side of the neck, common carotid artery bifurcated at a higher level than usual and 1.25 cm below the bifurcation, gave a common origin of lingual and superior thyroid artery from its medial side (thyorolingual trunk). No such anomaly was noted on the left side. This type of combination of variations has important clinical implications.
The Leading Edge, 2019
The offshore Lakshmi Field, located in the southern part of Cambay Basin in the CB/OS-2 block in ... more The offshore Lakshmi Field, located in the southern part of Cambay Basin in the CB/OS-2 block in western India, is a success story of transitioning from a plateauing gas field to an oil-producing asset. Hydrocarbons sourced from Hazira Shale at Lakshmi Field are trapped in inversion-related four-way dip closures. The reservoirs are within the Miocene-age Tarkeshwar and overlying Babaguru formations; both have excellent reservoir quality with porosity ranging from 25% to 30% and Darcy-scale permeability. During the initial exploration stage, presence of oil was established in the deeper lower Tarkeshwar sands. However, the full oil potential of the field was not realized in the early stage of development due to difficulty in characterizing laterally and vertically discontinuous thin sands. These sands are often not detected in conventional 3D seismic data due to severe attenuation-related masking by overlying thick gas sands. Given the uncertainty of the oil potential of the field, a...
Journal of Chromatographic Science, 2019
Among the secondary metabolites which are widely distributed in plants and foods in plant origin ... more Among the secondary metabolites which are widely distributed in plants and foods in plant origin flavonoids is important one. Flavonoids have antioxidant activities as free radical scavenging action. They also have anti-inflammatory, antiulcer and anti-carcinogenic activities. Diosmin and hesperidin, the metabolites of which are diosmetin and hesperitin respectively are considered in the present study. Diosmetin has anticancer, antioxidant and blood lipid lowering activities. It also enhances venous tone and microcirculation and by reducing systemic oxidative stress it protects capillaries. Hesperitin also has antioxidant, anti-inflammatory, blood lipid and cholesterol lowering, anti-carcinogenic activities. In the present study efforts were given to develop and validate a bioanalytical method for simultaneous estimation of diosmetin and hesperitin in human plasma by liquid chromatography electron spray ionization mass spectrometry with an application to the analysis of plasma samples obtained from the comparative pharmacokinetic studies on healthy human volunteers under the framework of bioequivalence study. The developed method for simultaneous determination and quantification of diosmetin and hesperitin in human plasma was validated as per the US-FDA guidelines. The validation parameters found within the specified regulatory limit, hence acceptable. The present method also has a short run time (6.0 min) and easy extraction process. The developed method was found to be simple, specific, highly selective, sensitive and reproducible. This was applied for the analysis of the volunteer plasma samples. On the basis of comparison of the AUC 0−t , the relative bioavailability of the test preparation was found 100.94 and 95.09% for diosmetin and hesperitin respectively of that of the reference preparation.
International Journal of Anatomy and Research, 2017
Background: Nutrient foramen (NF) is an opening on the surface of bone which conduct peripheral n... more Background: Nutrient foramen (NF) is an opening on the surface of bone which conduct peripheral nerve and nutrient artery. The major blood supply for long bones arise from this nutrient arteries. This supply is essential during the growing period and early phases of ossification and surgical interventions such as bone grafts, tumour resection, congenital pseudoarthrosis and in transplant techniques in Orthopaedics. This study was aimed to determine the number, direction, position of nutrient foramen and whether the nutrient foramina obey the general rule that is directed away from the growing end of the bone. Materials and Methods: The present study involved a review of 80 dry humerus of adult population of West Bengal (WB) which were taken from Department of Anatomy, ESI-PGIMSR & ESIC Medical College. Results: 60% bones had single foramen while 30% bones had double foramen, and 5% bones had triple foramen 5% bones showed no foramen. Major nutrient foramina were directed distally i.e. towards elbow and 76.85% NF were located on antero-medial surface of shaft and there were no change in the obliquity of the foramina. Conclusion: Majority of the bones followed "Growing End Theory". This study recorded data related to WB population, providing comparable ethnic data which may help in surgical procedures and in the interpretation of radiological images.
Indian journal of anaesthesia, 2017
Laryngoscopic manipulation and endotracheal intubation are noxious stimuli capable of producing t... more Laryngoscopic manipulation and endotracheal intubation are noxious stimuli capable of producing tachycardia, arrhythmias and hypertension. The aim of this study was to arrive at an optimal dose of dexmedetomidine by comparing two doses with placebo to attenuate stress response during laryngoscopy and endotracheal intubation. It was a randomised, prospective, double-blind placebo-controlled study. After Institutional Ethical Committee clearance, ninety patients of American Society of Anesthesiologists Physical Status 1 were enrolled in the study and divided into three equal groups. Group A received normal saline, Group B received injection dexmedetomidine 0.5 μg/kg and Group C received injection dexmedetomidine 0.75 μg/kg as infusion over 10 min. The general anaesthesia technique was standardised for all three groups. The primary outcome measures were haemodynamic response at 1, 3 and 5 min after intubation. The secondary outcome measures were to note down any adverse effects associa...
Review of Professional Management- A Journal of New Delhi Institute of Management, 2013
The paper focuses on the behavioural aspect of undergraduate students who want to pursue higher e... more The paper focuses on the behavioural aspect of undergraduate students who want to pursue higher educational especially professional courses and deals with how students perceive full time and part time courses along with course fee structures. This also shows the perception of students regarding job guarantee along with course duration. The finding in the paper gives a clear idea that job guarantee is an important factor while opting for professional courses irrespective of gender. The investigation here finds that if students were offered a professional course that would actualize their dreams, they were even willing to migrate to other cities. The paper also investigates preference order of sample students' career options in some selected sector among FMCG/CD, Retail, Manufacturing, IT, and BPO.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 2015
Acoustic-electric channels have been used in the recent past to send power and data through thin ... more Acoustic-electric channels have been used in the recent past to send power and data through thin metallic barriers. Acoustic-electric channels formed along a structure which are highly attenuative and nonreverberant could have potential applications in aerospace, nuclear, and oil industries, among others. This work considers data transmission along the length of a cylindrical pipe both when in air and when filled and immersed in water using shear waves of transverse polarity. To combat the effects of frequency selectivity and to address the available power constraints, a simple modulation scheme using noncoherent demodulation is employed for data transmission: chirp-on-off keying (Chirp-OOK). The wideband nature of the chirp waveform provides resilience against nulls in the channel response while making it possible to implement a simple noncoherent energy detector. Monte Carlo simulation results using measured channel responses suggest that the bit error rate performance of the sche...
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Papers by Soumya Chakraborty