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Search Results: 1 - 5 of 5 matches for " Kalamatianos "
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A nonextensive method for spectroscopic data analysis with artificial neural networks
Kalamatianos, Dimitrios;Anastasiadis, Aristoklis D.;Liatsis, Panos;
Brazilian Journal of Physics , 2009, DOI: 10.1590/S0103-97332009000400026
Abstract: in this paper we apply an evolving stochastic method to construct simple and effective artificial neural networks, based on the theory of tsallis statistical mechanics. our aim is to establish an automatic process for building a smaller network with high classification performance. we aim to assess the utility of the method based on statistical mechanics for the estimation of transparent coating material on security papers and cholesterol levels in blood samples. our experimental study verifies that there are indeed improvements in the overall performance in terms of classification success and at the size of network compared to other efficient backpropagation learning methods.
Aspectos éticos do uso de produtos fluorados no Brasil: uma vis?o dos formuladores de políticas públicas de saúde
Kalamatianos,Pola Alessandra; Narvai,Paulo Capel;
Ciência & Saúde Coletiva , 2006, DOI: 10.1590/S1413-81232006000100013
Abstract: fluoride has been used to prevent dental caries. it is used in supply water and toothpastes. one undesirable effect has been found: mild dental fluorosis. such stains have aroused concern among specialists. this paper examines, in the literature, ethical aspects resulting from the use of fluoride in public health associated with the "caries prevention versus mild fluorosis occurrence" contradiction and investigates the occurrence of any ethical dilemma among the professionals involved in decision on the use of such products. databases were assessed to identify papers through terms such as ética, bioética, ethics and fluor. the material contributed to the drawing up of a questionnaire answered by researchers and health authorities. the data provided by the interviews underwent content analysis. the ethics dilemma may be stated as: "the use of fluoride products to prevent dental caries has in public health the inconvenience of producing mild dental fluorosis in the population, however, the non-use of fluoride has the inconvenience of not preventing the appearance of a disease (caries) that can be prevented if such product is used." the dilemma has shown to be solved, by admitting that the use of such products would be fair and that its benefit would exceed its damages. nevertheless, some of the respondents admitted a violation of the principle of autonomy.
Optimal metabolic pathway activation
Diego Oyarzún,Brian Ingalls,Richard Middleton,Dimitrios Kalamatianos
Mathematics , 2008,
Abstract: This paper deals with temporal enzyme distribution in the activation of biochemical pathways. Pathway activation arises when production of a certain biomolecule is required due to changing environmental conditions. Under the premise that biological systems have been optimized through evolutionary processes, a biologically meaningful optimal control problem is posed. In this setup, the enzyme concentrations are assumed to be time dependent and constrained by a limited overall enzyme production capacity, while the optimization criterion accounts for both time and resource usage. Using geometric arguments we establish the bang-bang nature of the solution and reveal that each reaction must be sequentially activated in the same order as they appear in the pathway. The results hold for a broad range of enzyme dynamics which includes, but is not limited to, Mass Action, Michaelis-Menten and Hill Equation kinetics.
How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex
Yaki Setty, Chih-Chun Chen, Maria Secrier, Nikita Skoblov, Dimitrios Kalamatianos, Stephen Emmott
BMC Systems Biology , 2011, DOI: 10.1186/1752-0509-5-154
Abstract: The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1) the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2) we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1) under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2) under enhanced DCX expression in mice we predict a normal or a higher bipolar migration.We present here a system-wide computational model of neuronal migration that integrates theory and data within a precise, testable framework. Our model accounts for a range of observable behaviors and affords a computational framework to study aspects of neuronal migration as a complex process that is driven by a relatively simple molecular program. Analysis of the model generated new hypotheses and yet unobserved phenomena that may guide future experimental studies. This paper thus reports a first step toward a comprehensive in-silico model of neuronal migration.Neuronal migration is a highly dynamic process that is essential for the normal development and function of the mammalian brain. The migration process is regulated by cell-extrinsic signaling pathways and cell-intrinsic regulation and
Maternal Obesity Induced by Diet in Rats Permanently Influences Central Processes Regulating Food Intake in Offspring
Shona L. Kirk,Anne-Maj Samuelsson,Marco Argenton,Hannah Dhonye,Theodosis Kalamatianos,Lucilla Poston,Paul D. Taylor,Clive W. Coen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0005870
Abstract: Hypothalamic systems which regulate appetite may be permanently modified during early development. We have previously reported hyperphagia and increased adiposity in the adult offspring of rodents fed an obesogenic diet prior to and throughout pregnancy and lactation. We now report that offspring of obese (OffOb) rats display an amplified and prolonged neonatal leptin surge, which is accompanied by elevated leptin mRNA expression in their abdominal white adipose tissue. At postnatal Day 30, before the onset of hyperphagia in these animals, serum leptin is normal, but leptin-induced appetite suppression and phosphorylation of STAT3 in the arcuate nucleus (ARC) are attenuated; the level of AgRP-immunoreactivity in the hypothalamic paraventricular nucleus (PVH), which derives from neurones in the ARC and is developmentally dependent on leptin, is also diminished. We hypothesise that prolonged release of abnormally high levels of leptin by neonatal OffOb rats leads to leptin resistance and permanently affects hypothalamic functions involving the ARC and PVH. Such effects may underlie the developmental programming of hyperphagia and obesity in these rats.
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