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Search Results: 1 - 10 of 219507 matches for " Efthyvoulos C Kyriacou "
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A standardised protocol for texture feature analysis of endoscopic images in gynaecological cancer
Marios S Neofytou, Vasilis Tanos, Marios S Pattichis, Constantinos S Pattichis, Efthyvoulos C Kyriacou, Dimitris D Koutsouris
BioMedical Engineering OnLine , 2007, DOI: 10.1186/1475-925x-6-44
Abstract: We investigate texture feature variability for a variety of targets encountered in clinical endoscopy. All images were captured at clinically optimum illumination and focus using 720 × 576 pixels and 24 bits color for: (i) a variety of testing targets from a color palette with a known color distribution, (ii) different viewing angles, (iv) two different distances from a calf endometrial and from a chicken cavity. Also, human images from the endometrium were captured and analysed. For texture feature analysis, three different sets were considered: (i) Statistical Features (SF), (ii) Spatial Gray Level Dependence Matrices (SGLDM), and (iii) Gray Level Difference Statistics (GLDS). All images were gamma corrected and the extracted texture feature values were compared against the texture feature values extracted from the uncorrected images. Statistical tests were applied to compare images from different viewing conditions so as to determine any significant differences.For the proposed acquisition procedure, results indicate that there is no significant difference in texture features between the panoramic and close up views and between angles. For a calibrated target image, gamma correction provided an acquired image that was a significantly better approximation to the original target image. In turn, this implies that the texture features extracted from the corrected images provided for better approximations to the original images. Within the proposed protocol, for human ROIs, we have found that there is a large number of texture features that showed significant differences between normal and abnormal endometrium.This study provides a standardized protocol for avoiding any significant texture feature differences that may arise due to variability in the acquisition procedure or the lack of color correction. After applying the protocol, we have found that significant differences in texture features will only be due to the fact that the features were extracted from differen
Effect of zooming on texture features of ultrasonic images
Stavros K Kakkos, Andrew N Nicolaides, Efthyvoulos Kyriacou, Constantinos S Pattichis, George Geroulakos
Cardiovascular Ultrasound , 2006, DOI: 10.1186/1476-7120-4-8
Abstract: Eighteen still B-mode images of carotid plaques were zoomed during carotid scanning (zoom factor 1.3) and both images were transferred to a PC and normalised. Using bilinear and bicubic interpolation, the original images were interpolated in a process of simulating off-line zoom using the same interpolation factor. With the aid of the colour-coded image, carotid plaques of the original, zoomed and two resampled images for each case were outlined and histogram, first order and second order statistics were subsequently calculated.Most second order statistics (21/25, 84%) were significantly (p < 0.05) sensitive to image zooming during scanning, in contrast to histogram and first order statistics (4/25, 16%, p < 0.001, Fisher's exact test). Median (interquartile range) change of those features sensitive to zooming was 18.14% (4.94–28.43). Image interpolation restored these changes, the bicubic interpolation being superior compared to bilinear interpolation (p = 0.036).Texture analysis of ultrasonic plaques should be performed under standardised resolution settings; otherwise a resolution normalisation algorithm should be applied.Cross-sectional studies have shown that echolucent and heterogeneous internal carotid artery plaques on B-mode ultrasound scanning are associated with neurological symptoms [1-3]; similarly prospective studies have confirmed that these subjective plaque characteristics predict future neurological symptoms [4,5]. Our group has investigated objective, computer-assisted methods, which involved standardisation of ultrasonic images (normalisation) and echogenicity measurements [6,7]. We have also, like other groups, investigated objective methods of accessing plaque heterogeneity, known also as texture analysis, and found these helpful in separating symptomatic from asymptomatic plaques [8-12].Image resolution has a significant effect on texture analysis results; this has been shown by studies on remote sensing [13-15], and ultrasound [16]. Images ob
Imaging and Image Transfer in Emergency Medicine
Tobias Lindner,Hein Lamprecht,Efthyvoulos Kyriacou,Raoul Breitkreutz,Stefan Puig,Aristomenis K. Exadaktylos
Emergency Medicine International , 2013, DOI: 10.1155/2013/952672
Abstract:
Eigenanalysis of Electromagnetic Structures Based on the Finite Element Method  [PDF]
C. L. Zekios, P. C. Allilomes, G. A. Kyriacou
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.47138
Abstract: This article presents a review of our research effort on the eigenanalysis of open radiating waveguides and closed resonating structures. A two dimensional (2-D) hybrid Finite Element method in conjunction with a cylindrical harmonics expansion is established to formulate the open waveguide generalized eigenvalue problem. The key element of this approach refers to the adoption of a vector Dirichlet-to-Neumann map to rigorously enforce the continuity of the two field expansions along a truncation surface. The resulting algorithm was able to evaluate both surface and leaky eigenmodes. The eigenanalysis of three dimensional (3-D) structures involves vast research challenges, especially when they are electrically large and open-radiating. The effort herein is focused on the electrically large case including the losses due to the finite conductivity of metallic walls and objects as well as the loading material losses. The former is introduced through impedance or Leontovich boundary condition, resulting to a non-linear-polynomial generalized eigenvalue problem. A straightforward linearization solution is adopted along with a more efficient alternative technique which mimics analytical approaches. For this one the linear eigenproblem formulated assuming metals as perfect electric conductors is initially solved and their finite conductivity is accounted through impedance boundary conditions enforced locally on the resulting eigenvectors. Finally, some numerical results are presented to verify the performance of these methodologies along with a discussion on their possibilities for extension to open 3D structures as well as to characteristic modes eigenanalysis.
A feasibility study for the provision of electronic healthcare tools and services in areas of Greece, Cyprus and Italy
Stavroula G Mougiakakou, Efthyvoulos Kyriacou, Kostas Perakis, Homer Papadopoulos, Aggelos Androulidakis, Georgios Konnis, Riccardo Tranfaglia, Leandro Pecchia, Umberto Bracale, Constantinos Pattichis, Dimitrios Koutsouris
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-49
Abstract: The support of primary healthcare, home care and the continuous education of physicians are the three major issues that the proposed platform is trying to facilitate. The proposed system is based on state-of-the-art telemedicine systems and is able to provide the following healthcare services: i) Telecollaboration and teleconsultation services between remotely located healthcare providers, ii) telemedicine services in emergencies, iii) home telecare services for "at risk" citizens such as the elderly and patients with chronic diseases, and iv) eLearning services for the continuous training through seminars of both healthcare personnel (physicians, nurses etc) and persons supporting "at risk" citizens.These systems support data transmission over simple phone lines, internet connections, integrated services digital network/digital subscriber lines, satellite links, mobile networks (GPRS/3G), and wireless local area networks. The data corresponds, among others, to voice, vital biosignals, still medical images, video, and data used by eLearning applications. The proposed platform comprises several systems, each supporting different services. These were integrated using a common data storage and exchange scheme in order to achieve system interoperability in terms of software, language and national characteristics.The platform has been installed and evaluated in different rural and urban sites in Greece, Cyprus and Italy. The evaluation was mainly related to technical issues and user satisfaction. The selected sites are, among others, rural health centers, ambulances, homes of "at-risk" citizens, and a ferry.The results proved the functionality and utilization of the platform in various rural places in Greece, Cyprus and Italy. However, further actions are needed to enable the local healthcare systems and the different population groups to be familiarized with, and use in their everyday lives, mature technological solutions for the provision of healthcare services.The sou
A new model of care collaboration for community-dwelling elders: findings and lessons learned from the NORC-health care linkage evaluation
Corinne Kyriacou
International Journal of Integrated Care , 2009,
Abstract:
Bridging theory and practice: design and implementation of the NORC-SSP linkage evaluation
Corinne Kyriacou
International Journal of Integrated Care , 2009,
Abstract:
Uncovering the Distribution of Option Implied Risk Aversion  [PDF]
Maria Kyriacou, Jose Olmo, Marius Strittmatter
Journal of Mathematical Finance (JMF) , 2019, DOI: 10.4236/jmf.2019.92006
Abstract: This paper explores the dynamics of risk aversion of a representative agent with an iso-elastic utility function. In contrast to most of the existing literature, we estimate the coefficient of relative risk aversion from option prices. To do this, we transform the risk-neutral density function obtained from a cross-section of option prices to an objective distribution function that reflects individuals’ risk aversion through a CRRA utility function. The dynamics of the relative risk-aversion coefficient are obtained by repeating the same estimation procedure over rolling windows. This procedure uncovers strong variation in risk aversion over time. We also propose a simulation procedure to construct confidence intervals for the risk-aversion coefficient in each period. We assess the robustness of these confidence intervals under different assumptions on the data generating process of stock prices. The results imply a strong influence of volatility on the variation of risk aversion. In an empirical application, we compare the forecasting performance of our approach based on our risk-aversion estimates against the method proposed in [1]. Overall, we find that our simulation based approach obtains better forecasting results than bootstrap methods.
Wiener-Hopf Analysis of Planar Canonical Structures Loaded with Longitudinally Magnetized Plasma Biased Normally to the Extra-Ordinary Wave Propagation
George A. Kyriacou
PIER B , 2008, DOI: 10.2528/PIERB07121907
Abstract: The canonical problem of an extra-ordinary Transverse Electromagnetic wave propagating in a parallel plane waveguide with a semi-infinite upper conductor and loaded with magnetized plasma is considered. The homogeneous biasing constant magnetic field is assumed parallel to the substrate and normal to the wave propagation, which incidents normally on the truncated edge. The Wiener-Hopf technique is employed and the corresponding equations are formulated for the open-radiating structure as well as for a closed one resulting from the placement of a metallic shield parallel to the waveguide planes. Closed form field expressions are obtained for the shielded geometry, while the open geometry Kernel factorization is left for future extensions. Important non-reciprocal wave propagation phenomena are involved, which lend non-even function properties to the involved Kernels. Hence, their factorization becomes non-trivial requiring new mathematical approaches. Finally, a review of the involved non-reciprocal and/or unidirectional surface waves is given, which is related to the involved mathematical complexities.
A new model of care collaboration for community-dwelling elders: findings and lessons learned from the NORC-health care linkage evaluation
Corinne Kyriacou,Fredda Vladeck
International Journal of Integrated Care , 2011,
Abstract: Introduction and Background: Few financial incentives in the United States encourage coordination across the health and social care systems. Supportive Service Programs (SSPs), operating in Naturally Occurring Retirement Communities (NORCs), attempt to increase access to care and enhance care quality for aging residents. This article presents findings from an evaluation conducted from 2004 to 2006 looking at the feasibility, quality and outcomes of linking health and social services through innovative NORC-SSP and health organization micro-collaborations. Methods: Four NORC-SSPs participated in the study by finding a health care organization or community-based physicians to collaborate with on addressing health conditions that could benefit from a biopsychosocial approach. Each site focused on a specific population, addressed a specific condition or problem, and created different linkages to address the target problem. Using a case study approach, incorporating both qualitative and quantitative methods, this evaluation sought to answer the following two primary questions: 1) Have the participating sites created viable linkages between their organizations that did not exist prior to the study; and, 2) To what extent have the linkages resulted in improvements in clinical and other health and social outcomes? Results: Findings suggest that immediate outcomes were widely achieved across sites: knowledge of other sector providers’ capabilities and services increased; communication across providers increased; identification of target population increased; and, awareness of risks, symptoms and health seeking behaviors among clients/patients increased. Furthermore, intermediate outcomes were also widely achieved: shared care planning increased across providers; continuity of care was enhanced; disease management improved; and self care among clients improved. Finally, several linkage partnerships were also able to demonstrate improvements in distal outcomes: falls risk decreased; clinical indicators for diabetes management improved; and inappropriate hospitalizations decreased.
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