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Search Results: 1 - 10 of 259 matches for " Ananda Dasanayake "
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Tooth Decay in Alcohol Abusers Compared to Alcohol and Drug Abusers
Ananda P. Dasanayake,Saman Warnakulasuriya,Colin K. Harris,Derek J. Cooper,Timothy J. Peters,Stanley Gelbier
International Journal of Dentistry , 2010, DOI: 10.1155/2010/786503
Abstract: Alcohol and drug abuse are detrimental to general and oral health. Though we know the effects of these harmful habits on oral mucosa, their independent and combined effect on the dental caries experience is unknown and worthy of investigation. We compared 363 “alcohol only” abusers to 300 “alcohol and drug” abusers to test the hypothesis that various components of their dental caries experience are significantly different due to plausible sociobiological explanations. After controlling for the potential confounders, we observe that the “alcohol and drug” group had a 38% higher risk of having decayed teeth compared to the “alcohol only” group ( ). As expected, those who belonged to a higher social class ( ; 95%?? –2.75) and drank wine ( ; 95%?? –2.96) had a higher risk of having more filled teeth. We conclude that the risk of tooth decay among “alcohol only” abusers is significantly lower compared to “alcohol and drug” abusers. 1. Introduction Alcohol and drug dependence are conditions characterized by psychological, physiological, and pathological changes, all of which are directly relevant to dentistry [1]. The psychological effects and the personality changes in the abuser may affect the patient/dentist relationship as they take a reduced interest in seeking and paying for dental care. The physiological effect of alcohol intoxication may lead to the inability to understand and accept advice given by health care workers that may result in noncompliance. Pathological aspects of alcohol and drug abuse on dental and oral tissues have not been examined in detail except for its effects on the oral mucosa [2]. We hypothesize that “alcohol only” abusers have a significantly different caries experience compared to “alcohol and drug” abusers due to a variety of biological reasons. We propose the following biological model to explain the potential association between alcohol and drug abuse and dental caries. Microbial oxidation of ethanol in saliva in alcohol abusers will result in the formation of acetaldehyde [3] that may further alter the cariogenic oral flora by reducing their levels [4]. Warnakulasuriya et al. have shown that certain alcoholic beverages in the UK contain high levels of fluoride and those who consume three cans of beer a day in the UK would receive the recommended daily upper limit of fluoride through beer alone [5]. As most alcoholics may consume more than three cans, their exposure to higher levels of fluoride via alcoholic beverages may reduce their caries susceptibility. Alcoholic beverages may also enhance the fluoride release in
Association between Selected Oral Pathogens and Gastric Precancerous Lesions
Christian R. Salazar, Jinghua Sun, Yihong Li, Fritz Francois, Patricia Corby, Guillermo Perez-Perez, Ananda Dasanayake, Zhiheng Pei, Yu Chen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0051604
Abstract: We examined whether colonization of selected oral pathogens is associated with gastric precancerous lesions in a cross-sectional study. A total of 119 participants were included, of which 37 were cases of chronic atrophic gastritis, intestinal metaplasia, or dysplasia. An oral examination was performed to measure periodontal indices. Plaque and saliva samples were tested with real-time quantitative PCR for DNA levels of pathogens related to periodontal disease (Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, Actinobacillus actinomycetemcomitans) and dental caries (Streptococcus mutans and S. sobrinus). There were no consistent associations between DNA levels of selected bacterial species and gastric precancerous lesions, although an elevated but non-significant odds ratio (OR) for gastric precancerous lesions was observed in relation to increasing colonization of A. actinomycetemcomitans (OR = 1.36 for one standard deviation increase, 95% Confidence Interval = 0.87–2.12), P. gingivalis (OR = 1.12, 0.67–1.88) and T. denticola (OR = 1.34, 0.83–2.12) measured in plaque. To assess the influence of specific long-term infection, stratified analyses by levels of periodontal indices were conducted. A. actinomycetemcomitans was significantly associated with gastric precancerous lesions (OR = 2.51, 1.13–5.56) among those with ≥ median of percent tooth sites with PD≥3 mm, compared with no association among those below the median (OR = 0.86, 0.43–1.72). A significantly stronger relationship was observed between the cumulative bacterial burden score of periodontal disease-related pathogens and gastric precancerous lesions among those with higher versus lower levels of periodontal disease indices (p-values for interactions: 0.03–0.06). Among individuals with periodontal disease, high levels of colonization of periodontal pathogens are associated with an increased risk of gastric precancerous lesions.
Optimal Design of Minimum-Power Stimuli for Spiking Neurons
Isuru Dasanayake,Jr-Shin Li
Mathematics , 2010,
Abstract: In this article, we study optimal control problems of spiking neurons whose dynamics are described by a phase model. We design minimum-power current stimuli (controls) that lead to targeted spiking times of neurons, where the cases with unbounded and bounded control amplitude are considered. We show that theoretically the spiking period of a neuron, modeled by phase dynamics, can be arbitrarily altered by a smooth control. However, if the control amplitude is bounded, the range of possible spiking times is constrained and determined by the bound, and feasible spiking times are optimally achieved by piecewise continuous controls. We present analytic expressions of these minimum-power stimuli for spiking neurons and illustrate the optimal solutions with numerical simulations.
Design of Charge-Balanced Time-Optimal Stimuli for Spiking Neuron Oscillators
Isuru S. Dasanayake,Jr-Shin Li
Mathematics , 2012,
Abstract: In this paper, we investigate the fundamental limits on how the inter- spike time of a neuron oscillator can be perturbed by the application of a bounded external control input (a current stimulus) with zero net electric charge accumulation. We use phase models to study the dynamics of neurons and derive charge-balanced controls that achieve the minimum and maximum inter-spike times for a given bound on the control amplitude. Our derivation is valid for any arbitrary shape of the phase response curve and for any value of the given control amplitude bound. In addition, we characterize the change in the structures of the charge-balanced time-optimal controls with the allowable control amplitude. We demonstrate the applicability of the derived optimal control laws by applying them to mathematically ideal and experimentally observed neuron phase models, including the widely-studied Hodgkin-Huxley phase model, and by verifying them with the corresponding original full state-space models. This work addresses a fundamental problem in the field of neural control and provides a theoretical investigation to the optimal control of oscillatory systems.
Charge-Balanced Minimum-Power Controls for Spiking Neuron Oscillators
Isuru Dasanayake,Jr-Shin Li
Mathematics , 2011,
Abstract: In this paper, we study the optimal control of phase models for spiking neuron oscillators. We focus on the design of minimum-power current stimuli that elicit spikes in neurons at desired times. We furthermore take the charge-balanced constraint into account because in practice undesirable side effects may occur due to the accumulation of electric charge resulting from external stimuli. Charge-balanced minimum-power controls are derived for a general phase model using the maximum principle, where the cases with unbounded and bounded control amplitude are examined. The latter is of practical importance since phase models are more accurate for weak forcing. The developed optimal control strategies are then applied to both mathematically ideal and experimentally observed phase models to demonstrate their applicability, including the phase model for the widely studied Hodgkin-Huxley equations.
Total Electron Content and Anomalous Appearance of GPS Satellites as Pointers to Epicentre Identification of Major Japan Earthquake of 2011  [PDF]
Minakshi Devi, Ananda Kumar Barbara
Positioning (POS) , 2012, DOI: 10.4236/pos.2012.31002
Abstract: The paper presents an analysis of variations in Total Electron Content (TEC) observed through Global Positioning System (GPS) at Guwahati (26?10'N, 91?45'E), in relation to the Japan Earthquakes (EQs) of March 9 and 11, 2011. For this purpose, the azimuthal positions and trajectories of abnormally increased number of satellites at the epicentre location appearing into the Field Of View (FOV) of GPS antenna at Guwahati and consequent pseudo enhancement in TEC are taken as inputs. The paper discusses how the analysis results could provide warning alarms of two earthquakes possibly one on March 8 or 9 and the other on March 11 or 12, 2011 with epicenter positions around 135?E to 145?E and 35?N to 40?N, that coincides with location of Japan Earthquakes. A projected forecast on EQ magnitude of M > 8.5 is also made. The explanations to the observed modifications in TEC features and abnormal increase in number of satellites are purported to be the result of coupling between lithosphere and troposphere forced in by pre-earthquake processes that had spread the zone of activities to as far as Guwahati.
A Semi-automatic method for segmentation and 3D modeling of glioma tumors from brain MRI  [PDF]
S. Ananda Resmi, Tessamma Thomas
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.57048
Abstract: This work presents an efficient method for volume rendering of glioma tumors from segmented 2D MRI Datasets with user interactive control, by replacing manual segmentation required in the state of art methods. The most common primary brain tumors are gliomas, evolving from the cerebral supportive cells. For clinical follow-up, the evaluation of the preoperative tumor volume is essential. Tumor portions were automatically segmented from 2D MR images using morphological filtering techniques. These segmented tumor slices were propagated and modeled with the software package. The 3D modeled tumor consists of gray level values of the original image with exact tumor boundary. Axial slices of FLAIR and T2 weighted images were used for extracting tumors. Volumetric assessment of tumor volume with manual segmentation of its outlines is a time-consuming process and is prone to error. These defects are overcome in this method. Authors verified the performance of our method on several sets of MRI scans. The 3D modeling was also done using segmented 2D slices with the help of medical software package called 3D DOCTOR for verification purposes. The results were validated with the ground truth models by the Radiologist.
Identification of segmental duplications in the human genome
Ananda Fonseka
Sri Lanka Journal of Bio-Medical Informatics , 2013, DOI: http://dx.doi.org/10.4038/sljbmi.v3i1.2467
Abstract: Sequencing the human genome early in this decade marked one of the greatest achievements in the advancement in to science. Soon it opened up a great opportunity to the scientific community worldwide with a massive amount of biological data to be explored.Segmental duplication is one of the structural variations found in the genome sequence. It counts for about 5% of genome and with relatively long segments of sequence of more than 1KB in length and more than 90% of sequence identity. Segmental duplications are distributed within the chromosome and throughout the genome and mostly denced in the subtelometric and pericentrometric regions. Segmental duplications play major rule in the evolutionary history and its association with genetic disorders.This review intends to explore in to the publications on previous studies and to tools and methodology they followed to achieve of their objective of identifying segmental duplications. Finding the similar sequences was done by local sequence alignment algorithms, most frequently with Blast program followed by global alignment algorithms. Further some other tools such as Blat, DupMasker and MUMmer also were being used.
Peacekeeping in Africa: Capabilities and Culpabilities
Ananda Nel
Scientia Militaria : South African Journal of Military Studies , 2012, DOI: 10.5787/30-2-183
Abstract: African states increasingly carry the responsibility for the promotion and maintenance of peace and security on the African continent. This book provides a detailed discussion on the efforts made by African states to do so and explores the ways and means to enhance Africa's peacekeeping capacity. An analysis is also made of external efforts to develop and enhance the capacity of African states to undertake peacekeeping operations. The content of this book is based on a two year research project conducted by means of fieldwork in more than 20 countries and interviews with more than 200 policy makers and members of civil society.
NETLab: An Online Laboratory Management System
Ananda Maiti
International Journal of Online Engineering (iJOE) , 2010, DOI: 10.3991/ijoe.v6i2.1292
Abstract: Online hardware-based educational laboratories are increasingly being deployed in traditional on-campus as well as Web-based distance-learning courses around the world. An online laboratory generally will consist of several hardware-based remote experiments. However, one particular experiment can be performed at a time by an individual student or a group of students which require a careful scheduling of the experiments. For the proper implementation of an online laboratory an efficient laboratory management system (LMS) is thus essential. Also for an online laboratory, the students need to fully understand the experimental system setup and feel comfortable as in an actual laboratory environment which, however, can be effectively done by adding suitable videos and animations etc. Besides, the students should be able to run the remote experiments, extract, save and analyze the data and submit laboratory reports online. The front end of the laboratory management system should be made browser-based so that one can use the laboratory facility from anywhere. Also, for the teachers, the laboratory management system should include an online evaluation for the quiz/viva-voce, checking experimental data, grading of submitted laboratory reports and feedback for the students. In this paper, we describe the design and prototype implementation of an online laboratory management system (for use with shared hardware-based remote laboratory resources) which may be employed for running internet-based online laboratory courses for geographically dispersed Institutions.
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