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Search Results: 1 - 10 of 651 matches for " Selin Metin "
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From Occasional Choices to Inevitable Musts: A Computational Model of Nicotine Addiction
Selin Metin,N. Serap Sengor
Computational Intelligence and Neuroscience , 2012, DOI: 10.1155/2012/817485
Abstract: Although, there are considerable works on the neural mechanisms of reward-based learning and decision making, and most of them mention that addiction can be explained by malfunctioning in these cognitive processes, there are very few computational models. This paper focuses on nicotine addiction, and a computational model for nicotine addiction is proposed based on the neurophysiological basis of addiction. The model compromises different levels ranging from molecular basis to systems level, and it demonstrates three different possible behavioral patterns which are addict, nonaddict, and indecisive. The dynamical behavior of the proposed model is investigated with tools used in analyzing nonlinear dynamical systems, and the relation between the behavioral patterns and the dynamics of the system is discussed. 1. Introduction The value of an experience or an action is imposed by the reward gained afterwards. An action inducing a greater reward is sensed as a superior action, and thus the successive occurrences of this type of actions are rewarded more frequently [1]. In the case of addiction, the abusive substance (nicotine, drugs, etc.) has a value greater than other forms of reward imposing actions. Some persistent modifications in the synaptic plasticity in the neural subsystems of the brain are believed to lead to addiction; thus, it is claimed that addiction is a disorder in the mesolimbic system which develops by the modification of responses to rewarding actions [1–4]. Mislead by the overemphasized reward perception, the addicts compulsively seek for the substance they are addicted to. Since the reward mechanism has been persistently changed, addicts usually cannot be completely cured, and they often relapse into drug use after treatment [2]. Considering the negative social and physical impacts of addiction, any attempt to understand the neural mechanisms underlying this phenomenon is valuable. So, in this study, a computational model of addiction is given. We propose a model for nicotine addiction which is composed of a cortico-striato-thalamic action selection circuit and a dopamine signaling unit operating according to reinforcement learning. The proposed model is based on the interaction of neural structures known to be taking role in addiction and the effect of neurotransmitters on these structures. The proposed model focuses on the neurophysiological basis of addiction and the results obtained by the model show that the model is capable of demonstrating different behavioral patterns. (See the Supplementary Material containing the source codes
360 Derece Performans De erlendirme ve Geri Bildirim: Bir üniversite Mediko-Sosyal Merkezi Birim Amirlerinin Y netsel Yetkinliklerinin De erlendirilmesi üzerine Pilot Uygulama rne i(360 Degree Performance Appraisal And Feedback: “A Pilot Study Illustration in Appraising the Managerial Skills of Supervisors Working in Health Care Centre of a University”)
Selin Metin CAMG?Z,?. Nurdan ALPERTEN
Y?netim ve Ekonomi , 2006,
Abstract: In this study, “360 Degree Performance Appraisal” which is one of the most current and controversial issues of human resource practices is extensively examined and supported with an empirical research. The study contains 2 parts. After explaining the necessity and the general utilities of the classical performance appraisal system, the first theoretical part shifts to the emergence of 360 degree performance appraisal, discusses its distinctive benefits over the classical appraisal system and focuses its attention to the raters (superiors, subordinates, peers, self) involving in the 360 degree performance appraisal.The second empirical part illustrates the development of 360 degree performance appraisal system as well as its application and sample feedback reports for feedback purposes in order to appraise the managerial skills of supervisors working in Health Care Centre of a public university.
Changes of Reef Community near Ku Lao Cham Islands (South China Sea) after Sangshen Typhoon  [PDF]
Yuri Ya. Latypov, Nikolai Selin
American Journal of Climate Change (AJCC) , 2012, DOI: 10.4236/ajcc.2012.11004
Abstract: Coral reefs of Ku Lao Cham Islands in the Central Vietnam were studied over a quarter of a century. It was established that the reefs of these Islands were lost after the Sangshen typhoon and a heavy flood, which happened in 2006. As a result of these natural phenomena a significant part of coral populations was physically destroyed, and a powerful export of clay substances from the nearest Vietnamese coast and from the Bung River, flowing into the sea opposite the Islands, causing abundant sedimentation and death of almost all the remaining scleractinian corals. At present, where formerly there were coral reefs, now there is algal-alcyonarian stage of succession of reef communities. This is typical, as a rule, for restoration of reefs after a destructive typhoon effect.
Implementation of substitution treatment in Finland: Beyond rationalisation and medicalisation
Jani Selin
Nordic Studies on Alcohol and Drugs , 2011, DOI: 10.2478/v10199-011-0003-6
Abstract: AIMS - Finnish treatment of drug abuse has during the last two decades shifted from a predominantly psychosocial approach to a more medical mode. This is especially evident in the rapid implementation of substitution treatments (STs). My aim is to show that labelling this development as ‘medicalisation’ or ‘rationalisation’ as a form of medical progress will not increase our understanding of the change. MATERIAL AND DESIGN - I analysed texts from several periodicals with psychosocial, social policy and medical perspectives between 1997 and 2005. Four basic conceptual and argumentative underpinnings emerged which gave credence to the medical and rational approach, and the validity of these four elements was then investigated. I also collected all the texts on drug addiction and its treatment from two medical journals in 1965-1976 to examine the way in which drug addiction was conceptualised during this earlier phase. RESULTS - The material shows that there are at least four reasons why medicalisation and rationalisation cannot explain the implementation of substitution treatments in Finland. First, progress in medical research on addiction did not make STs necessary. Second, the effectiveness of substitution treatments hinges on a particular kind of scientific rationality that cannot be equated with rationality per se. Third, it was not the 1990s and 2000s that drug addiction was coded as a medical problem for the first time. Fourth, it is difficult to include into the medicalisation theory how people actively want to be ‘medicalised’. Medical knowledge and technology open up new domains of knowledge with possible relations to practices of power and offer people new ways of self-understanding. How these different practices work is a question of empirical research. Both ‘rationalisation’ and ‘medicalisation’ are concepts often used in an inflationary way, and this may make them insensitive as analytical instruments.
17. sajandi usuline situatsioon Vene-Rootsi piirialal
Adrian Selin
M?etagused. Hüperajakiri , 2004,
Abstract: The article is based on two data corpora. The first corpus is the so called "Porubezhnye (Borderline) Acts" which is a part of the 17th century Novgorod Ambassador Court Archives held in the Archives of St. Petersburg Branch of the Institute of Russian History. The second corpus is a part of Kammararkivet, named Baltiska Fogder kenskaper, and consists of the economic acts and deeds made in Ivangorod, Iam, Koporie, Oreshek (Noteburg), Nevsky Ostrozhek (Nyen), Gdov and on the territories ascribed to the fortresses in 1580-1589 and 1612-1618. During the Novgorod-Swedish administration 1611-1617 these relations were pliable (there were even parleys about a possible contact between the two Churches), but after the Stolbovo Treaty 1617 interrelations between the churches had become deteriorating. The Swedish government tried to control the Orthodox clergy in the annexed districts, while the Moscow state attempted to leave it under the control of the archbishop of Novgorod. In the mid-17th century new factors in the everyday life in the Russian-Swedish border region revealed. A new wave of Orthodox migrants from Ingermanland and the Kexholm district in Sweden arrived at the Moscow State and at the same time patriarch Nikon's church reform was held. This circumstance has partly shaped the general attitudes towards the migrants: traditionally they were perceived as schismatics. The most important factor was the language barrier between the migrants, Izhorians and Karelians, and the autochthonous Russian population in the borderline area and the inside territories where the migrants had settled (the so called Tver' Karelia). To sum up, the transition of some Novgorod Orthodox districts to the Lutheran State had created a principally new precedent. As known, the concepts of confession and citizenship were practically identical in the 16th -17th century popular thought, when Orthodoxy automatically meant Moscow citizenship. The transition of a number of Orthodox parishioners to foreign citizenship had significantly troubled both the Moscow Governors and the clergy, and had created an atmosphere of uncertainty, where nobody knew who factually had the right to appoint priests, etc. The possible way out was to appoint a local bishop for the Orthodox parishes in Ingermanland but that, of course, was impossible for the Moscow governors. The result was a paradoxical situation where the church ruling, justice, and administration of the Orthodox parishes were handed over to probsts - special officials appointed by the Swedish Lutheran government.
Computationally Efficient Scale Covariant Time-Frequency Distributions
Selin Aviyente
EURASIP Journal on Advances in Signal Processing , 2009, DOI: 10.1155/2009/204351
Abstract: Scale is a physical attribute of a signal which occurs in many natural settings. Time-frequency distributions (TFDs) belonging to Cohen's class are invariant to time and frequency shifts, but are not necessarily covariant to the time scalings of the signal. Conditions on the time-frequency kernel for yielding a scale covariant distribution have been previously derived (Cohen, 1995). In this paper, a new class of computationally efficient scale covariant distributions is introduced. These distributions are constructed using the eigendecomposition of time-frequency kernels (Burrus et al., 1997). The performance of this new class of distributions is illustrated with examples and is compared to conventional scale covariant distributions.
Effect of Low Velocity Impact Damage on Buckling Properties  [PDF]
Ahmet YAPICI, Mehmet METIN
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.13019
Abstract: The work described herein consists of experimental measurement of the post-impact buckling loads of E- glass/epoxy laminates. Composite samples with stacking sequence of [+45/?45/90/0]2s were subjected to low-velocity impact loading at energy levels of 36, 56.13, 79.95, 110.31 and 144 J. The impact tests were conducted with a specially developed vertical drop weight testing machine. Impact parameters like peak load, absorbed energy, deflection at peak load and damage area were evaluated and compared. Damaged specimens were subjected to compressive axial forces and buckling loads of the specimens were obtained. The relation between energy levels and buckling loads is investigated.
Spectral Analysis for Fractional Hydrogen Atom Equation  [PDF]
Erdal Bas, Funda Metin
Advances in Pure Mathematics (APM) , 2015, DOI: 10.4236/apm.2015.513070
Abstract: In this paper, spectral analysis of fractional Sturm Liouville problem defined on (0, 1], having the singularity of type \"\"?at zero and researched the fundamental properties of the eigenfunctions and eigenvalues for the operator. We show that the eigenvalues and eigenfunctions of the problem are real and orthogonal, respectively.
Quantification of Effective Connectivity in the Brain Using a Measure of Directed Information
Ying Liu,Selin Aviyente
Computational and Mathematical Methods in Medicine , 2012, DOI: 10.1155/2012/635103
Abstract: Effective connectivity refers to the influence one neural system exerts on another and corresponds to the parameter of a model that tries to explain the observed dependencies. In this sense, effective connectivity corresponds to the intuitive notion of coupling or directed causal influence. Traditional measures to quantify the effective connectivity include model-based methods, such as dynamic causal modeling (DCM), Granger causality (GC), and information-theoretic methods. Directed information (DI) has been a recently proposed information-theoretic measure that captures the causality between two time series. Compared to traditional causality detection methods based on linear models, directed information is a model-free measure and can detect both linear and nonlinear causality relationships. However, the effectiveness of using DI for capturing the causality in different models and neurophysiological data has not been thoroughly illustrated to date. In addition, the advantage of DI compared to model-based measures, especially those used to implement Granger causality, has not been fully investigated. In this paper, we address these issues by evaluating the performance of directed information on both simulated data sets and electroencephalogram (EEG) data to illustrate its effectiveness for quantifying the effective connectivity in the brain.
Density-Dependent Habitat Selection in a Growing Threespine Stickleback Population
Ulrika Candolin,Marita Selin
International Journal of Zoology , 2012, DOI: 10.1155/2012/378913
Abstract: Human-induced eutrophication has increased offspring production in a population of threespine stickleback Gasterosteus aculeatus in the Baltic Sea. Here, we experimentally investigated the effects of an increased density of juveniles on behaviours that influence survival and dispersal, and, hence, population growth—habitat choice, risk taking, and foraging rate. Juveniles were allowed to choose between two habitats that differed in structural complexity, in the absence and presence of predators and conspecific juveniles. In the absence of predators or conspecifics, juveniles preferred the more complex habitat. The preference was further enhanced in the presence of a natural predator, a perch Perca fluviatilis (behind a transparent Plexiglas wall). However, an increased density of conspecifics relaxed the predator-enhanced preference for the complex habitat and increased the use of the open, more predator-exposed habitat. Foraging rate was reduced under increased perceived predation risk. These results suggest that density-dependent behaviours can cause individuals to choose suboptimal habitats where predation risk is high and foraging rate low. This could contribute to the regulation of population growth in eutrophicated areas where offspring production is high. 1. Introduction Individuals are usually forced to balance costs against benefits when choosing a habitat [1, 2]. Structurally complex habitats are often more favourable than open habitats, as they provide more resources and better refuges against predators [3–5]. However, complex habitats can also be costly if they harbour more predators and competitors than open habitats [6, 7]. In addition, the costs and benefits of choosing a habitat depend on what other individuals in the population are doing [8–10]. The profitability of a habitat decreases the more individuals that occupy it, because of a reduction in the amount of resources available per individual. As high quality habitats become saturated, more and more individuals are forced to occupy poor-quality habitats [11, 12]. Interactions among individuals will then influence habitat selection, and, thus, density-dependent processes will affect individual fitness and the temporal and spatial distribution of the population. Human activities are currently altering habitats at an unprecedented rate and scale around the world. The consequences that this will have for the populations that were well adapted to the past conditions are poorly known. An environment that is changing rapidly because of human activities is the Baltic Sea. Increased input of
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