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Search Results: 1 - 10 of 224152 matches for " Martin P. Mintchev "
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Development of Wearable Semi-invasive Blood Sampling Devices for Continuous Glucose Monitoring: A Survey  [PDF]
Gang Wang, Martin P. Mintchev
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55B009
Abstract: Semi-invasive blood sampling devices mimic the way female mosquitoes extract blood from a host. They generally consist of a microneedle, a microactuator for needle insertion, a blood extraction mechanism and a blood glucose sensor. These devices have great potential to overcome the major disadvantages of several current blood glucose monitoring methods. Over last two decades, extensive research has been made in all of these related fields. More recently, several wearable devices for semi-invasive blood sampling have been developed. This review aims at summarizing the current state-of-the-art development and utilization of such wearable devices for continuous monitoring of blood glucose levels, with a special attention on design considerations, fabrication technologies and testing methods.
Pseudobezoars: Technology Progress and New Prospects as a Medical Platform  [PDF]
Orly Yadid-Pecht, Martin P. Mintchev
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55B003
Abstract: In recent years, pseudobezoars have been a subject of research, mainly serving as a basis for a new non-invasive alternative to obesity treatment. A pill incorporating the technology has been proven to be successful as a weight loss therapy. It enables patients to sustain a diet longer, due to an increase in the level of satiety, resulting in a smaller amount of food intake. Utilization of the technology has recently found new prospects in another organ of the GI tract, the colon. Pseudobezoar technology can be utilized as an enhanced method for colon cancer screening and also as an alternative carrier for bacterial therapy.
Gastric Electrical Stimulation for the Treatment of Obesity: From Entrainment to Bezoars—A Functional Review
Martin P. Mintchev
ISRN Gastroenterology , 2013, DOI: 10.1155/2013/434706
Abstract:
Gastric Electrical Stimulation for the Treatment of Obesity: From Entrainment to Bezoars—A Functional Review
Martin P. Mintchev
ISRN Gastroenterology , 2013, DOI: 10.1155/2013/434706
Abstract: Growing worldwide obesity epidemic has prompted the development of two main treatment streams: (a) conservative approaches and (b) invasive techniques. However, only invasive surgical methods have delivered significant and sustainable benefits. Therefore, contemporary research exploration has focused on the development of minimally invasive gastric manipulation methods featuring a safe but reliable and long-term sustainable weight loss effect similar to the one delivered by bariatric surgeries. This antiobesity approach is based on placing external devices in the stomach ranging from electrodes for gastric electrical stimulation to temporary intraluminal bezoars for gastric volume displacement for a predetermined amount of time. The present paper examines the evolution of these techniques from invasively implantable units to completely noninvasive patient-controllable implements, from a functional, rather than from the traditional, parametric point of view. Comparative discussion over the available pilot and clinical studies related to gastric electrical stimulation outlines the promises and the fallacies of this concept as a reliable alternative anti-obesity strategy. 1. Introduction 1.1. Obesity as a World Wide Health Problem The World Health Organization (WHO) announced recently that worldwide obesity has increased more than twice since 1980 [1]. WHO statistics outlined 1.5 billion overweight adults in 2008. A significant percentage of them were obese: nearly 300 million women and over 200 million men. An earlier report [2] revealed a diminishing initial age of obesity onset, with nearly 43 million overweight children under the age of five [1]. Even veterinary scientists have researched obesity in pets and its correlation with the obesity of their owners [3]. The WHO list of world’s top 25 fattest countries covers all continents except Antarctica and sub-Saharan Africa [1, 4]. 65% of the world’s population lives in countries where overweight and obesity kill more people than underweight and hunger. Moreover, obesity rates in the United States, Australia, and Canada increase faster than the overall worldwide rate [5]. Projections up to 2030 indicate that more than 36% of the population in the developed countries will be overweight and more than 22%—obese [6]. WHO prognosis for 2015 is that overweight adults will balloon to 2.3 billion, affecting both the developed and developing world [1, 2, 6]. Obesity is an important key factor for comorbidities and related mortality and is also increasingly considered as a type of cellular malnutrition and a
Acoustic and Intraluminal Ultrasonic Technologies in the Diagnosis of Diseases in Gastrointestinal Tract: A Review  [PDF]
Qian Lu, Orly Yadid-Pecht, Dan Sadowski, Martin P. Mintchev
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55B015
Abstract: Gastrointestinal (GI) auscultation (listening to sounds from stomach and bowel) has been applied for abdominal physical assessment for many years. This article evaluates the technique involved in listening to both bowel and stomach sounds and the significance of both normal and abnormal GI auscultation findings. Moreover, intraluminal ultrasonic techniques have been widely used for gastrointestinal disease diagnosis by providing intraluminal images since 1980s, this article also reviews the existing intraluminal ultrasonic technology for diagnosing of GI disorders.
Colometer: A real-time quality feedback system for screening colonoscopy
Dobromir Filip,Xuexin Gao,Leticia Angulo-Rodríguez,Martin P Mintchev
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i32.4270
Abstract: AIM: To investigate the performance of a new software-based colonoscopy quality assessment system. METHODS: The software-based system employs a novel image processing algorithm which detects the levels of image clarity, withdrawal velocity, and level of the bowel preparation in a real-time fashion from live video signal. Threshold levels of image blurriness and the withdrawal velocity below which the visualization could be considered adequate have initially been determined arbitrarily by review of sample colonoscopy videos by two experienced endoscopists. Subsequently, an overall colonoscopy quality rating was computed based on the percentage of the withdrawal time with adequate visualization (scored 1-5; 1, when the percentage was 1%-20%; 2, when the percentage was 21%-40%, etc.). In order to test the proposed velocity and blurriness thresholds, screening colonoscopy withdrawal videos from a specialized ambulatory colon cancer screening center were collected, automatically processed and rated. Quality ratings on the withdrawal were compared to the insertion in the same patients. Then, 3 experienced endoscopists reviewed the collected videos in a blinded fashion and rated the overall quality of each withdrawal (scored 1-5; 1, poor; 3, average; 5, excellent) based on 3 major aspects: image quality, colon preparation, and withdrawal velocity. The automated quality ratings were compared to the averaged endoscopist quality ratings using Spearman correlation coefficient. RESULTS: Fourteen screening colonoscopies were assessed. Adenomatous polyps were detected in 4/14 (29%) of the collected colonoscopy video samples. As a proof of concept, the Colometer software rated colonoscope withdrawal as having better visualization than the insertion in the 10 videos which did not have any polyps (average percent time with adequate visualization: 79% ± 5% for withdrawal and 50% ± 14% for insertion, P < 0.01). Withdrawal times during which no polyps were removed ranged from 4-12 min. The median quality rating from the automated system and the reviewers was 3.45 [interquartile range (IQR), 3.1-3.68] and 3.00 (IQR, 2.33-3.67) respectively for all colonoscopy video samples. The automated rating revealed a strong correlation with the reviewer’s rating (ρ coefficient= 0.65, P = 0.01). There was good correlation of the automated overall quality rating and the mean endoscopist withdrawal speed rating (Spearman r coefficient= 0.59, P = 0.03). There was no correlation of automated overall quality rating with mean endoscopists image quality rating (Spearman r coefficient= 0.41, P
Finite Temperature Quantum Field Theory with Impurities
M. Mintchev,P. Sorba
Statistics , 2004, DOI: 10.1088/1742-5468/2004/07/P07001
Abstract: We apply the concept of reflection-transmission (RT) algebra, originally developed in the context of integrable systems in 1+1 space-time dimensions, to the study of finite temperature quantum field theory with impurities in higher dimensions. We consider a scalar field in $(s+1)+1$ space-time dimensions, interacting with impurities localized on $s$-dimensional hyperplanes, but without self-interaction. We discuss first the case $s=0$ and extend afterwards all results to $s>0$. Constructing the Gibbs state over an appropriate RT algebra, we derive the energy density at finite temperature and establish the correction to the Stefan-Boltzmann law generated by the impurity. The contribution of the impurity bound states is taken into account. The charge density profiles for various impurities are also investigated.
Bosonization and Scale Invariance on Quantum Wires
B. Bellazzini,M. Mintchev,P. Sorba
Physics , 2006, DOI: 10.1088/1751-8113/40/10/017
Abstract: We develop a systematic approach to bosonization and vertex algebras on quantum wires of the form of star graphs. The related bosonic fields propagate freely in the bulk of the graph, but interact at its vertex. Our framework covers all possible interactions preserving unitarity. Special attention is devoted to the scale invariant interactions, which determine the critical properties of the system. Using the associated scattering matrices, we give a complete classification of the critical points on a star graph with any number of edges. Critical points where the system is not invariant under wire permutations are discovered. By means of an appropriate vertex algebra we perform the bosonization of fermions and solve the massless Thirring model. In this context we derive an explicit expression for the conductance and investigate its behavior at the critical points. A simple relation between the conductance and the Casimir energy density is pointed out.
Quantum Fields on Star Graphs with Bound States at the Vertex
B. Bellazzini,M. Mintchev,P. Sorba
Physics , 2008, DOI: 10.1063/1.3318159
Abstract: We investigate the propagation of a massless scalar field on a star graph, modeling the junction of $n$ quantum wires. The vertex of the graph is represented by a point-like impurity (defect), characterized by a one-body scattering matrix. The general case of off-critical scattering matrix with bound and/or antibound states is considered. We demonstrate that the contribution of these states to the scalar field is fixed by causality (local commutativity), which is the key point of our investigation. Two different regimes of the theory emerge at this stage. If bound sates are absent, the energy is conserved and the theory admits unitary time evolution. The behavior changes if bound states are present, because each such state generates a kind of damped harmonic oscillator in the spectrum of the field. These oscillators lead to the breakdown of time translation invariance. We study in both regimes the electromagnetic conductance of the Luttinger liquid on the quantum wire junction. We derive an explicit expression for the conductance in terms of the scattering matrix and show that antibound and bound states have a different impact, giving raise to oscillations with exponentially damped and growing amplitudes respectively.
Scattering in the Presence of a Reflecting and Transmitting Impurity
M. Mintchev,E. Ragoucy,P. Sorba
Physics , 2002, DOI: 10.1016/S0370-2693(02)02776-4
Abstract: We investigate factorized scattering from a reflecting and transmitting impurity. Bulk scattering is non trivial, provided that the bulk scattering matrix depends separately on the spectral parameters of the colliding particles, and not only on their difference. We show that a specific extension of a boundary algebra encodes the underlying scattering theory. The total scattering operator is constructed in this framework and shown to be unitary.
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