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Maria S Zakynthinaki

Maria S Zakynthinaki
Hellenic Medditeranean University · Electronics

BSc, MSc, MPhil, MSc, PhD

About

53
Publications
17,973
Reads
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805
Citations
Additional affiliations
September 2013 - present
Hellenic Mediterranean University
Position
  • Lecturer
September 2011 - present
Technical University of Crete
Position
  • Lecturer
July 2011 - present
Technical University of Crete
Position
  • Lecturer

Publications

Publications (53)
Article
Full-text available
Estimating the heart rate (HR) response to exercises of a given intensity without the need of direct measurement is an open problem of great interest. We propose here a model that can estimate the heart rate response to exercise of constant intensity and its subsequent recovery, based on soft computing techniques. Multilayer perceptron artificial n...
Article
Full-text available
This paper presents a novel work on localization of transmitters using triangulation with sensors at fixed positions. This is achieved when three or more sensors cover the whole area, a factor which enables the system to perform localization via triangulation. The network needs to keep a high detection rate which, in most cases, is achieved by adeq...
Article
Full-text available
Study aim : To analyse the distribution of effort in the 800 m event at the IAAF World Athletics Championships in London 2017 (outdoor, 44 men, 45 women) and in Birmingham 2018 (indoor, 9 men, 14 women). Material and methods : A total of 187 individual performances during heats, semi-finals, and finals were analysed. The official split times of eac...
Article
In this paper we explore the difficulties engineering undergraduates encounter with tertiary mathematics. Results from our survey (N = 71) show that students in our sample face issues mostly related to the challenging nature of university mathematics, the absence of worked examples during lectures and the discontinuity of school and university math...
Article
Recently, there has been much controversy over the International Association of Athletics Federation (IAAF) regulations regarding eligibility to compete and natural testosterone levels in female athletes. Much interest lies in the analysis of Caster Semenya's extraordinary performance. The objective of this work were, a) Complete an analysis of Cas...
Article
Full-text available
The ability to stabilize the gun, a crucial factor for performance in air pistol Olympic shooting, is thought to be strongly related to the muscular work of the shooter´s shoulder and forearm. The objective of the present study was to confirm this relationship by analysing the influence of maximal finger flexor forces and maximal isometric shoulder...
Conference Paper
A model, based on multilayer perceptron artificial neural networks, is proposed for the estimation of the heart rate response to exercise of constant intensity and the subsequent recovery. The numerical results are very encouraging.
Article
Full-text available
The objective of the study was to examine, via use of a simple specific test, the correlation between body sway and performance in Juvenile Olympic shooters, to compare the differences in body morphology between different shooting modalities and to know if the anthropometric profile of a shooter influences performance. 38 national level juvenile sh...
Article
Full-text available
The purpose of this study was to examine whether the difference in elite-standard track and field performance between women athletes with and without hyperandrogenism reaches the 10–12% difference in performance between men and women, using only results from elite-standard track and field final competitions. Officially available data from two hyper...
Article
Full-text available
The purpose of this study was to assess the veracity of the Court of Arbitration for Sport's assertion that sex-differences in athletic performance in elite-standard track and field competition is of the order of 10-12%. Exponential curves were fitted to the data of selected track and field events of the finals of all IAAF World Championships and O...
Article
Full-text available
RESUMEN El principal objetivo de este estudio es realizar un estudio previo a la validación de un test de medición del equilibrio en tiro olímpico sin el uso de la pistola. Para ello, se han comparado los resultados del análisis del movimiento del centro de presiones (CP) de dos pruebas de equilibrio estático: en la primera prueba se usó una mancue...
Article
Full-text available
The present study implements a stochastic optimization technique to optimally manage freshwater pumping from coastal aquifers. Our simulations utilize the well-known sharp interface model for saltwater intrusion in coastal aquifers together with its known analytical solution. The objective is to maximize the total volume of freshwater pumped by the...
Article
Full-text available
Study aim: To apply a recently proposed dynamical systems model to simulate, for the first time, the heart rate (HR) response to exercise of time-dependent intensity. Material and methods: The applied model is expressed in the form of two coupled ordinary differential equations, one giving the rate of change of HR and the other providing the time d...
Article
Full-text available
The ability to stabilize the gun is crucial for performance in Olympic pistol shooting and is thought to be related to the shooters muscular strength. The present study examines the relation between performance and finger flexor force as well as shoulder abduction isometric force in senior male air pistol shooting. 46 Spanish national level shooter...
Article
Full-text available
The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise). Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The mod...
Preprint
Full-text available
The present study validates use of a dumbbell to simulate the air pistol in female Olympic shooting, examining, at the same time, the relation between body sway and performance. The study’s participants were 23 senior female Olympic pistol shooters who competed at a Spanish air pistol championship. The participants’ performance was measured at comp...
Preprint
The present study validates use of a dumbbell to simulate the air pistol in female Olympic shooting, examining, at the same time, the relation between body sway and performance. The study’s participants were 23 senior female Olympic pistol shooters who competed at a Spanish air pistol championship. The participants’ performance was measured at comp...
Article
Full-text available
Study aim: We examine the body sway differences between a) pistol and rifle and b) elite and national level senior male Olympic shooters, as well as the possible relation between body sway and performance at competition in Olympic shooting. Material and methods: Two body sway tests (feet together and feet apart) were performed by 28 Spanish male s...
Article
Full-text available
Study aim: We examine the body sway differences between a) pistol and rifle and b) elite and national level senior male Olympic shooters, as well as the possible relation between body sway and performance at competition in Olympic shooting.
Article
Full-text available
We present and validate a test able to provide reliable body sway measurements in air pistol shooting, without the use of a gun. 46 senior male pistol shooters who participated in Spanish air pistol championships participated in the study. Body sway data of two static bipodal balance tests have been compared: during the first test, shooting was sim...
Article
Full-text available
Saltwater intrusion in freshwater aquifers is a problem of increasing significance in areas nearby the coastline. Apart from natural disastrous phenomena, such as earthquakes or floods, intense pumping human activities over the aquifer areas may change the chemical composition of the freshwater aquifer. Working towards the direction of real time ma...
Article
Full-text available
A method that provides a three-dimensional representation of the basin of attraction of a dynamical system from experimental data was applied to the problem of dynamic balance restoration. The method is based on the density of the data on the phase space of the system under study and makes use of modeling and numerical curve fitting tools. For the...
Article
Full-text available
This paper aims to analyse the use of anabolic drugs among Greek students participating in school championships of physical education (PE). In order to do it, a survey was conducted during the 2008 to 2009 academic year in suburban, urban and metropolitan areas in Greece. The sample was 2,535 high school students from the 10 to 12th grade, particip...
Article
The stochastic optimization method ALOPEX IV has been successfully applied to the problem of detecting possible changes in the maternal heart rate kinetics during pregnancy. For this reason, maternal heart rate data were recorded before, during and after gestation, during sessions of exercises of constant mild intensity; ALOPEX IV stochastic optimi...
Article
We have studied the effect of moderate physical activity that is performed by healthy women during their entire pregnancy on their perception of health status. Eighty sedentary women were assigned randomly to either an exercise group (n = 40) or a control group (n = 40). Maternal perception of health status and several pregnancy outcomes were recor...
Article
Full-text available
Resumen Históricamente la relación entre la actividad física y el embarazo no ha estado completamente clara. La gran cantidad de estudios científicos no han producido suficientes hallazgos que otorguen información clara y concreta sobre la dosis adecuada de ejercicio durante la gestación. El presente trabajo pretende conocer la relación entre los h...
Article
Full-text available
We show how asymmetries in the movement patterns during the process of regaining balance after perturbation from quiet stance can be modeled by a set of coupled vector fields for the derivative with respect to time of the angles between the resultant ground reaction forces and the vertical in the anteroposterior and mediolateral directions. In our...
Article
Full-text available
We present a method of modeling the basin of attraction as a three-dimensional function describing a two-dimensional manifold on which the dynamics of the system evolves from experimental time series data. Our method is based on the density of the data set and uses numerical optimization and data modeling tools. We also show how to obtain analytic...
Article
Full-text available
Historically the relationship between physical activity and pregnancy has not been totally clear. Despite the large number of scientific studies carried out, the appropriate amount of exercise during pregnancy is still not clarified and the question remains open. The aim of the present study was to understand the relationship between the physical a...
Article
Full-text available
The existence of time-delayed phases ([1][1]) is not supported by oxygen uptake kinetics data. Despite many attempts for a number of years, no convincing physiological mechanism for such behavior has been proven to exist. The reason is that these time-delayed phases are a figment of the incorrect
Article
Full-text available
TO THE EDITOR: Not one of the proposed physiological mechanisms support the existence of time-delayed instantaneous stepwise increments in oxygen demand that mark the beginning of each time-delayed phase and are the very foundation of the time-delayed three-phase exponential model. The chance of finding physiological mechanisms to support such beha...
Article
We examined the effect of light-intensity resistance exercise training that is performed during the second and third trimester of pregnancy by previously sedentary and healthy women on the type of delivery and on the dilation, expulsion, and childbirth time. We randomly assigned 160 sedentary women to either a training (n=80) or a control (n=80) gr...
Article
The stochastic optimization method ALOPEX IV is successfully applied to the problem of estimating the time dependency of the physiological demand in response to exercise. This is a fundamental and unsolved problem in the area of exercise physiology, where the lack of appropriate tools and techniques forces the assumption and the use of a constant d...
Article
Full-text available
We demonstrate the successful application of ALOPEX stochastic optimization to the problem of calculating the optimal critical curve in a dynamical systems model of the process of regaining balance after perturbation from quiet stance. Experimental data provide the time series of angles for which the subjects were able to regain balance after an in...
Article
Full-text available
We present a mathematical model, in the form of two coupled ordinary differential equations, for the heart rate kinetics in response to exercise. Our heart rate model is an adaptation of the model of oxygen uptake kinetics of Stirling et al. [21]; a physiological justification for this adaptation, as well as the physiological basis of our heart rat...
Article
Full-text available
Abstract A substantial amount of research has investigated the influence of physical exercise during pregnancy on certain maternal and foetal parameters. Regarding the behaviour of the foetal heart rate (FHR) during the maternal exercise certain controversy exists; as several investigations have studied this parameter obtaining varied results. To t...
Article
Full-text available
We present a geometric analysis of the model of Stirling. In particular we analyze the curvature of a heart rate time series in response to a step like increment in the exercise intensity. We present solutions for the point of maximum curvature which can be used as a marker of physiological interest. This marker defines the point after which the he...
Article
Full-text available
In this paper, we present an application of a number of tools and concepts for modeling and analyzing raw, unaveraged, and unedited breath-by-breath oxygen uptake data. A method for calculating anaerobic capacity is used together with a model, in the form of a set of coupled nonlinear ordinary differential equations to make predictions of the \(\do...
Article
Full-text available
This paper applies geometric methods developed to understand chaos and transport in Hamiltonian systems to the study of power distribution in nonlinear waveguide arrays. The specific case of two linearly coupled chi((2)) waveguides is modeled and analyzed in terms of transport and geometry in the phase space. This gives us a transport problem in th...
Article
Full-text available
Una cantidad importante de investigaciones han valorado la influencia del ejercicio físico durante el embarazo en ciertos parámetros fetales. En relación al comportamiento de la frecuencia cardiaca foetal (FCF) durante la realización del ejercicio existe cierta controversia, muchas investigaciones han estudiado este parámetro con resultados variado...
Article
Full-text available
Stochastic optimization is applied to the problem of optimizing the fit of a model to the time series of raw physiological (heart rate) data. The physiological response to exercise has been recently modeled as a dynamical system. Fitting the model to a set of raw physiological time series data is, however, not a trivial task. For this reason and in...
Article
Full-text available
We present a new model of the underlying dynamics of the oxygen uptake VO2(v,t) kinetics for various exercise intensities. This model is in the form of a set of nonlinear coupled vector fields for the VO2(v,t) and v, the derivative of the exercise intensity with respect to time. We also present a new and novel means for calculating the oxygen deman...
Article
Full-text available
We investigate stability and the maintenance of balance with the use of tools from dynamical systems. In particular we investigate the application of such tools to the study of the ground reaction forces resulting from an athlete being perturbed from quiet stance. We develop a nonlinear model consisting of a set of coupled vector fields for the der...
Article
Full-text available
We have investigated the performance of an adaptive optics system subjected to changing atmospheric conditions, under the guidance of the ALOPEX stochastic optimization. Atmospheric distortions are smoothed out by means of a deformable mirror, the shape of which can be altered in order to follow the rapidly changing atmospheric phase fluctuations....
Article
We present computer simulations of a tip-tilt adaptive optics system, where stochastic optimization is applied to the problem of dynamic compensation of atmospheric turbulence. The system uses a simple measure of the light intensity that passes through a mask and is recorded on the image plane, to generate signals for the tip-tilt mirror. A feedbac...
Article
Full-text available
Some first results of simulation studies for the control of deformable mirrors used to correct the effects of atmospheric turbulence to the image quality in a 1.5m telescope at a wavelength of 0.5µn are reported here. Images based on Kolmogorov turbulence have been formed and an attempt has been made to correct them via a deformable mirror, inciden...
Article
Quench of superconducting wires can be regarded as probabilistic phenomena due to local instability in the wire. This paper describes statistical scattering in quench current of a.c. superconducting wires and coils using Weibull statistics. Experimental results revealed that, in some cases, the scattering was expressed by mixed Weibull distribution...
Article
Optical observations by ground-based astronomical telescopes have long been affected by the distorting effects of the earth's atmosphere. A real time system of optical elements (Adaptive Optics (AO) system) must be introduced to change the distorted wavefront into a nearly planar one. Adaptive corrections are to be achieved by a deformable or a seg...
Article
Adaptive corrections of distorted astronomical images are to be achieved by a segmented mirror, which is driven by an optimization device using the ALOPEX stochastic optimization algorithm. The ALOPEX II version of this algorithm has been modified in order to overcome the sensitivity of the known method on the choice of the free parameter, by norma...
Article
Full-text available
We give examples of how mathematical modelling is used to model processes in sport. We start by giving a general overview of areas cur-rently employing mathematical tools to analyze the processes involved. We then go onto look in more detail at the use of mathematics to model the physiological response to exercise. It should also be noted that this...
Article
Full-text available
In the applied mathematics literature there exist a significant number of tools that can reveal the interaction between mother and fetus during rest and also during and after exercise. These tools are based on techniques from a number of areas such as signal processing, time series analysis, neural networks, heart rate variability as well as dynami...

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Projects

Projects (7)
Project
Determine the possible factors influencing performance in Olympic shooting