Parcourir par auteur "Nakas, C. T."
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Accuracy and cut-off point selection in three-class classification problems using a generalization of the Youden index
Nakas, C. T.; Alonzo, T. A.; Yiannoutsos, C. T. (2010)We study properties of the index J(3), defined as the accuracy, or the maximum correct classification, for a given three class classification problem Specifically, using J(3) one can assess the discrimination between the ... -
Ancestral populations perform better in a novel environment: domestication of Mediterranean fruit fly populations from five global regions
Diamantidis, A. D.; Carey, J. R.; Nakas, C. T.; Papadopoulos, N. T. (2011)Geographically isolated populations of a species may differ in several aspects of life history, morphology, behaviour and genetic structure as a result of adaptation in ecologically diverse habitats. We used a global ... -
Assessing multiple-group diagnostic problems with multi-dimensional receiver operating characteristic surfaces: Application to proton MR Spectroscopy (MRS) in HIV-related neurological injury
Yiannoutsos, C. T.; Nakas, C. T.; Navia, B. A.; Proton, M. R. S. Consortium (2008)We present the multi-dimensional Receiver Operating Characteristic (ROC) surface, a plot of the true classification rates of tests based on levels of biological markers, for multi-group discrimination, as an extension of ... -
A comparative study among landraces of Phaseolus vulgaris L. and P. coccineus L. based on molecular, physicochemical and sensory analysis for authenticity purposes
Mavromatis, A. G.; Arvanitoyannis, I. S.; Chatzitheodorou, V.; Kaltsa, A.; Patsiaoura, I.; Nakas, C. T. (2012)The common and runner beans are the two most widely cultivated species because of their highly nutritive value for humans and animals. This study was undertaken to interpret data from physicochemical, sensory and molecular ... -
A comparison of tests for restricted orderings in the three-class case
Alonzo, T. A.; Nakas, C. T.; Yiannoutsos, C. T.; Bucher, S. (2009)A variety of methods for comparing three distributions have been proposed in the literature. These methods assess the same null hypothesis of equal distributions but differ in the alternative hypothesis they consider. The ... -
Competition among Species of Stored-Product Psocids (Psocoptera) in Stored Grain
Athanassiou, C. G.; Kavallieratos, N. G.; Throne, J. E.; Nakas, C. T. (2014)We evaluated the competition among stored-product psocid species by conducting two series of laboratory experiments. In the first series, three species of Liposcelididae were used: Liposcelis bostrychophila, Liposcelis ... -
Condition-Dependent Effects of Mating on Longevity and Fecundity of Female Medflies: The Interplay between Nutrition and Age of Mating
Papanastasiou, S. A.; Nakas, C. T.; Carey, J. R.; Papadopoulos, N. T. (2013)Background: In various species mating exerts direct and indirect effects on female demographic traits ranging from life span shortening to behavioural shifts. A wealth of data regarding effects of nutrition on longevity ... -
Considerations on what constitutes a 'qualified statistician' in regulatory guidelines
Gerlinger, C.; Edler, L.; Friede, T.; Kieser, M.; Nakas, C. T.; Schumacher, M.; Seldrup, J.; Victor, N. (2012)International regulatory guidelines require that a qualified statistician takes responsibility for the statistical aspects of a clinical trial used for drug licensing. No consensus on what constitutes a qualified statistician ... -
Construction of Confidence Regions in the ROC Space after the Estimation of the Optimal Youden Index-Based Cut-Off Point
Bantis, L. E.; Nakas, C. T.; Reiser, B. (2014)After establishing the utility of a continuous diagnostic marker investigators will typically address the question of determining a cut-off point which will be used for diagnostic purposes in clinical decision making. The ... -
DEVELOPMENTS IN ROC SURFACE ANALYSIS AND ASSESSMENT OF DIAGNOSTIC MARKERS IN THREE-CLASS CLASSIFICATION PROBLEMS
Nakas, C. T. (2014)This article reviews current state of the art of ROC surface analysis and illustrates its use through an application on a pancreatic cancer diagnostic marker. Receiver Operating Characteristic (ROC) surfaces have been ... -
Diapause termination of Rhagoletis cerasi pupae is regulated by local adaptation and phenotypic plasticity: escape in time through bet-hedging strategies
Moraiti, C. A.; Nakas, C. T.; Papadopoulos, N. T. (2014)Persistence and thriving of univoltine, herbivore insect species of the temperate zone rely on obligate diapause response that ensures winter survival and synchronization with host phenology. We used a stenophagous fruit ... -
Dual reproductive cost of aging in male medflies: Dramatic decrease in mating competitiveness and gradual reduction in mating performance
Papanastasiou, S. A.; Diamantidis, A. D.; Nakas, C. T.; Carey, J. R.; Papadopoulos, N. T. (2011)Although age-based effects on the reproductive success of males have been reported in several animal taxa the cost of aging on male mating success in lekking species has not been fully explored. We used the Mediterranean ... -
Early abnormal amplitude-integrated electroencephalography (aEEG) is associated with adverse short-term outcome in premature infants
Soubasi, V.; Mitsakis, K.; Sarafidis, K.; Griva, M.; Nakas, C. T.; Drossou, V. (2012)Background: In preterm infants with IVH the electrocortical background activity is affected and there is a correlation between the severity of cerebral injury to the degree of depression, however the usefulness of the early ... -
Estimating changes in mean population age using the death distributions of live-captured medflies
Carey, J. R.; Papadopoulos, N. T.; Papanastasiou, S.; Diamantidis, A.; Nakas, C. T. (2012)1. A simple, low-cost approach to estimating population ageing was introduced based on a modified version of the captive cohort method a technique developed earlier (Carey et al., Aging Cell, 7, 426437, 2008) in which ... -
Generalization of Youden index for multiple-class classification problems applied to the assessment of externally validated cognition in Parkinson disease screening
Nakas, C. T.; Dalrymple-Alford, J. C.; Anderson, T.; Alonzo, T. A. (2013)Routine cognitive screening in Parkinson disease (PD) has become essential for management, to track progression and to assess clinical status in therapeutic trials. Patients with mild cognitive impairment (PD-MCI) are more ... -
Geographical variation in adult life-history traits of the European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae)
Moraiti, C. A.; Nakas, C. T.; Koppler, K.; Papadopoulos, N. T. (2012)To understand the evolution of local adaptation, the interplay between natural selection and gene flow should be considered. Rhagoletis cerasi L. (Diptera: Tephritidae) is a patchily distributed, stenophagous species of ... -
The influence of extrauterine life on the aEEG maturation in normal preterm infants
Soubasi, V.; Mitsakis, K.; Nakas, C. T.; Petridou, S.; Sarafidis, K.; Griva, M.; Agakidou, E.; Drossou, V. (2009)Objective: To study, the maturational changes of the amplitude-integrated electroencephalogram (aEEG) in preterm infants without neurological disorders and especially the influence of the duration of extrauterine life, ... -
Life history evolution in a globally invading tephritid: Patterns of survival and reproduction in medflies from six world regions
Diamantidis, A. D.; Papadopoulos, N. T.; Nakas, C. T.; Wu, S.; MÜller, H. G.; Carey, J. R. (2009)Comparisons among populations from different localities represent an important tool in the study of evolution. Medflies have colonized many temperate and tropical areas all over the world during the last few centuries. In ... -
The MoCA Well-suited screen for cognitive impairment in Parkinson disease
Dalrymple-Alford, J. C.; MacAskill, M. R.; Nakas, C. T.; Livingston, L.; Graham, C.; Crucian, G. P.; Melzer, T. R.; Kirwan, J.; Keenan, R.; Wells, S.; Porter, R. J.; Watts, R.; Anderson, T. J. (2010)Objective: To establish the diagnostic accuracy of the Montreal Cognitive Assessment (MoCA) when screening externally validated cognition in Parkinson disease (PD), by comparison with a PD-focused test (Scales for Outcomes ... -
Nonparametric Bayesian estimation of the three-way receiver operating characteristic surface
Inacio, V.; Turkman, A. A.; Nakas, C. T.; Alonzo, T. A. (2011)We describe a nonparametric Bayesian approach for estimating the three-way ROC surface based on mixtures of finite Polya trees (MFPT) priors. Mixtures of finite Polya trees are robust models that can handle nonstandard ...