University of Central Greece
Lamia, Greece

The University of Central Greece , was a public university located in Central Greece, which was founded by the Greek Government in April 2003 in Lamia. It comprised two departments, the Department of Computer Science and Biomedical Informatics and the Department of Regional Economic Development. The first students were admitted to the University of Central Greece in September 2004, at which time only the informatics department was in operation. A total of 71 students were enrolled to that department, of whom 11 graduated in October 2008. The Department of Regional Economic Growth, which was founded in 2005, began its operation in the academic year 2005-2006. The University operated two campuses, in the municipalities of Lamia and Livadeia. The Department of Computer Science and Biomedical Informatics was housed in the former Lamia Academy, near the old municipal hospital and the public aquatics centre. Administrative functions and a cafeteria were housed in the ground floor to facilitate student access. The first floor housed facilities such as lecture classes, two labs, one computer cluster, as well as administrative services and the faculty offices. A library was also available, which was occasionally used by students and for faculty meetings.The University was closed in June 2013. The Department of Computer Science and Biomedical Informatics was added to the University of Thessaly with the campus remaining in Lamia, while the Department of Regional Economic Growth was merged with the Department of Economic and Regional Development of Panteion University. Wikipedia.

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Bangalore S.,New York University | Pursnani S.,California Pacific Medical Center | Kumar S.,University of Nebraska at Omaha | Bagos P.G.,University of Central Greece
Circulation | Year: 2013

Background-Contemporary studies have shown that spontaneous but not procedural myocardial infarction (MI) is related to subsequent mortality. Whether percutaneous coronary intervention (PCI) reduces spontaneous (nonprocedural) MI is unknown. Methods and Results-PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for randomized clinical trials until October 2012 comparing PCI with optimal medical therapy (OMT) for stable ischemic heart disease and reporting MI outcomes: spontaneous nonprocedural MI, procedural MI, and all MI, including procedure-related MI. Given the varying length of follow-up between trials, a mixed-effect Poisson regression meta-analysis was used. From 12 randomized clinical trials with 37 548 patient-years of follow-up, PCI compared with OMT alone was associated with a significantly lower incident rate ratio (IRR) for spontaneous nonprocedural MI (IRR=0.76; 95% confidence interval [CI], 0.58-0.99) at the risk of a higher rate of procedural MI (IRR=4.11; 95% CI, 2.53-6.88) without any difference in the risk of all MI (IRR=0.96; 95% CI, 0.74-1.21). The point estimate for PCI versus OMT for all-cause mortality (IRR=0.88; 95% CI, 0.75-1.03) and cardiovascular mortality (IRR=0.70; 95% CI, 0.44-1.09) paralleled that for spontaneous nonprocedural MI (but not procedural or all nonfatal MI), although these were not statistically significant. Conclusions-PCI compared with OMT reduced spontaneous MI at the risk of procedural MI without any difference in all MI. Consistent with prior studies showing that spontaneous MI but not procedural MI is related to subsequent mortality, in the present report the point estimate for reduced mortality with PCI compared with OMT paralleled the prevention of spontaneous MI with PCI. Further studies are needed to determine whether these associations are causal. © 2012 American Heart Association, Inc.

Tsirigos K.D.,National and Kapodistrian University of Athens | Bagos P.G.,University of Central Greece | Hamodrakas S.J.,National and Kapodistrian University of Athens
Nucleic Acids Research | Year: 2011

We describe here OMPdb, which is currently the most complete and comprehensive collection of integral β-barrel outer membrane proteins from Gram-negative bacteria. The database currently contains 69 354 proteins, which are classified into 85 families, based mainly on structural and functional criteria. Although OMPdb follows the annotation scheme of Pfam, many of the families included in the database were not previously described or annotated in other publicly available databases. There are also cross-references to other databases, references to the literature and annotation for sequence features, like transmembrane segments and signal peptides. Furthermore, via the web interface, the user can not only browse the available data, but submit advanced text searches and run BLAST queries against the database protein sequences or domain searches against the collection of profile Hidden Markov Models that represent each family's domain organization as well. The database is freely accessible for academic users at and we expect it to be useful for genome-wide analyses, comparative genomics as well as for providing training and test sets for predictive algorithms regarding transmembrane β-barrels. © The Author(s) 2010.

Polemis M.L.,University of Piraeus | Fotis P.N.,University of Central Greece
Energy Policy | Year: 2013

This paper uses the generalized method of moments (GMM) estimation to a panel data error correction model (ECM) in order to measure the asymmetries in the transmission of shocks to input prices and exchange rate onto the wholesale and retail gasoline price, respectively. For this purpose, we use an updated data set of 6369 weekly observations (January 2000 to February 2011) for 11 euro zone countries. The results indicate the existence of asymmetric responses in the retail and wholesale segment due to possible reasons (oligopolistic structure of the refining industry, existence of consumers search costs, regulatory and legal barriers). © 2013 Elsevier Ltd.

Epitropakis M.G.,University of Patras | Plagianakos V.P.,University of Central Greece | Plagianakos V.P.,University of Patras | Vrahatis M.N.,University of Patras
Information Sciences | Year: 2012

In recent years, the Particle Swarm Optimization has rapidly gained increasing popularity and many variants and hybrid approaches have been proposed to improve it. In this paper, motivated by the behavior and the spatial characteristics of the social and cognitive experience of each particle in the swarm, we develop a hybrid framework that combines the Particle Swarm Optimization and the Differential Evolution algorithm. Particle Swarm Optimization has the tendency to distribute the best personal positions of the swarm particles near to the vicinity of problem's optima. In an attempt to efficiently guide the evolution and enhance the convergence, we evolve the personal experience or memory of the particles with the Differential Evolution algorithm, without destroying the search capabilities of the algorithm. The proposed framework can be applied to any Particle Swarm Optimization algorithm with minimal effort. To evaluate the performance and highlight the different aspects of the proposed framework, we initially incorporate six classic Differential Evolution mutation strategies in the canonical Particle Swarm Optimization, while afterwards we employ five state-of-the-art Particle Swarm Optimization variants and four popular Differential Evolution algorithms. Extensive experimental results on 25 high dimensional multimodal benchmark functions along with the corresponding statistical analysis, suggest that the hybrid variants are very promising and significantly improve the original algorithms in the majority of the studied cases. © 2012 Elsevier Inc. All rights reserved.

Bagos P.G.,University of Central Greece
Statistical Applications in Genetics and Molecular Biology | Year: 2013

In genetic association studies (GAS) as well as in genome-wide association studies (GWAS), the mode of inheritance (dominant, additive and recessive) is usually not known a priori. Assuming an incorrect mode of inheritance may lead to substantial loss of power, whereas on the other hand, testing all possible models may result in an increased type I error rate. The situation is even more complicated in the metaanalysis of GAS or GWAS, in which individual studies are synthesized to derive an overall estimate. Metaanalysis increases the power to detect weak genotype effects, but heterogeneity and incompatibility between the included studies complicate things further. In this review, we present a comprehensive summary of the statistical methods used for robust analysis and genetic model selection in GAS and GWAS. We then discuss the application of such methods in the context of meta-analysis. We describe the theoretical properties of the various methods and the foundations on which they are based. We also present the available software implementations of the described methods. Finally, since only few of the available robust methods have been applied in the meta-analysis setting, we present some simple extensions that allow robust meta-analysis of GAS and GWAS. Possible extensions and proposals for future work are also discussed. © 2013 Walter de Gruyter GmbH, Berlin/Boston.

Bagos P.G.,University of Central Greece
Statistics in Medicine | Year: 2012

In many applications two correlated estimates of an effect size need to be considered simultaneously to be combined or compared. Apparently, there is a need for calculating their covariance, which however requires access to the individual data that may not be available to a researcher performing the analysis. We present a simple and efficient method for calculating the covariance of two correlated log-odds ratios. The method is very simple, is based on the well-known large sample approximations, can be applied using only data that are available in the published reports and more importantly, is very general, because it is shown to encompass several previously derived estimates (multiple outcomes, multiple treatments, dose-response models, mutually exclusive outcomes, genetic association studies) as special cases. By encompassing the previous approaches in a unified framework, the method allows easily deriving estimates for the covariance concerning problems that were not easy to be obtained otherwise. We show that the method can be used to derive the covariance of log-odds ratios from matched and unmatched case-control studies that use the same cases, a situation that has been addressed in the past only using individual data. Future applications of the method are discussed. © 2012 John Wiley & Sons, Ltd.

Background: Meta-analysis is a popular methodology in several fields of medical research, including genetic association studies. However, the methods used for meta-analysis of association studies that report haplotypes have not been studied in detail. In this work, methods for performing meta-analysis of haplotype association studies are summarized, compared and presented in a unified framework along with an empirical evaluation of the literature.Results: We present multivariate methods that use summary-based data as well as methods that use binary and count data in a generalized linear mixed model framework (logistic regression, multinomial regression and Poisson regression). The methods presented here avoid the inflation of the type I error rate that could be the result of the traditional approach of comparing a haplotype against the remaining ones, whereas, they can be fitted using standard software. Moreover, formal global tests are presented for assessing the statistical significance of the overall association. Although the methods presented here assume that the haplotypes are directly observed, they can be easily extended to allow for such an uncertainty by weighting the haplotypes by their probability.Conclusions: An empirical evaluation of the published literature and a comparison against the meta-analyses that use single nucleotide polymorphisms, suggests that the studies reporting meta-analysis of haplotypes contain approximately half of the included studies and produce significant results twice more often. We show that this excess of statistically significant results, stems from the sub-optimal method of analysis used and, in approximately half of the cases, the statistical significance is refuted if the data are properly re-analyzed. Illustrative examples of code are given in Stata and it is anticipated that the methods developed in this work will be widely applied in the meta-analysis of haplotype association studies. © 2011 Bagos; licensee BioMed Central Ltd.

We present an analytical framework for the performance evaluation of laser satellite uplinks over the major probabilistic impairments, i.e., atmospheric turbulence and beam wander. Specifically, we consider a ground-station-to-space laser uplink with a Gaussian beam wave model, and we focus on the particular regime assuming untracked beams where beam wandering takes place. In that regime, the modulated gamma-gamma distribution has been proposed as an effective irradiance model to characterize the combined effect of turbulence and beam wander. First we provide a closed-form expression of the probability density function and deduce the fundamental statistics of the new model. Then we evaluate the performance of the laser system assuming coherent detection for several modulation schemes. An appropriate set of numerical results is presented to verify the accuracy of the derived expressions. © 2011 Optical Society of America.

Sandalidis H.G.,University of Central Greece
IEEE Transactions on Communications | Year: 2011

The performance of optical wireless systems deteriorates to a large extent from the presence of turbulence and pointing error effects. To meet the typical bit error rate (BER) targets for reliable communications within the practical ranges of signal-to-noise ratio, error control coding schemes are often proposed. This paper investigates the error performance for convolutional coded on-off keying free-space optical systems through symbol by symbol interleaved channels characterized by strong turbulence and/or pointing error effects. We consider several channel types and derive exact analytical expressions for the pairwise error probability. These expressions are applied to obtain upper bounds on the BER performance using the transfer function technique. © 2011 IEEE.

Maglogiannis I.,University of Central Greece
Journal of Healthcare Engineering | Year: 2012

As the Electronic Health Record (EHR) systems constantly expand to support more clinical activities and their implementations in healthcare organizations become more widespread, several communities have been working intensively for several years to develop open access and open source EHR software, aiming at reducing the costs of EHR deployment and maintenance. In this paper, we describe and evaluate the most popular open source electronic medical records such as openEMR, openMRS and patientOS, providing their technical features and potentials. These systems are considered quite important due to their prevalence. The article presents the key features of each system and outlines the advantages and problems of Open Source Software (OSS) Systems through a review of the literature, in order to demonstrate the possibility of their adoption in modern electronic healthcare systems. Also discussed are the future trends of OS EHRs in the context of the Personal Health Records and mobile computing paradigm.

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