University of Cyprus

About: University of Cyprus is a education organization based out in Nicosia, Cyprus. It is known for research contribution in the topics: Large Hadron Collider & Context (language use). The organization has 3624 authors who have published 15157 publications receiving 412135 citations.

Beamforming for MISO Interference Channels with QoS and RF Energy Transfer

Abstract: We consider a multiuser multiple-input single-output interference channel where the receivers are characterized by both quality-of-service (QoS) and radio-frequency (RF) energy harvesting (EH) constraints. We consider the power splitting RF-EH technique where each receiver divides the received signal into two parts a) for information decoding and b) for battery charging. The minimum required power that supports both the QoS and the RF-EH constraints is formulated as an optimization problem that incorporates the transmitted power and the beamforming design at each transmitter as well as the power splitting ratio at each receiver. We consider both the cases of fixed beamforming and when the beamforming design is incorporated into the optimization problem. For fixed beamforming we study three standard beamforming schemes, the zero-forcing (ZF), the regularized zero-forcing (RZF) and the maximum ratio transmission (MRT); a hybrid scheme, MRT-ZF, comprised of a linear combination of MRT and ZF beamforming is also examined. The optimal solution for ZF beamforming is derived in closed-form, while optimization algorithms based on second-order cone programming are developed for MRT, RZF and MRT-ZF beamforming to solve the problem. In addition, the joint-optimization of beamforming and power allocation is studied using semidefinite programming (SDP) with the aid of rank relaxation.

Vitamin E and cancer: An insight into the anticancer activities of vitamin E isomers and analogs

Abstract: Current observations in the literature suggest that vitamin E may be a suitable candidate for the adjuvant treatment of cancer. Even though historically most research focused on α-tocopherol, more recent evidence suggests that the other isomers of vitamin E (β-, γ- and δ-tocopherols and α-, β-, γ- and δ-tocotrienols) differ in their proapoptotic potencies. The main focus of this communication is the current understanding of the molecular mechanisms regulated by vitamin E isomers and their analogs during the induction of apoptosis. This review highlights that the mitochondria are the major target for the induction of apoptosis by vitamin E isomers and analogs and that the various signaling pathways regulated by these agents are likely to contribute towards maximizing the intrinsic pathway of apoptosis triggered initially by the mitochondria. Overall, the presentation of recent studies from the literature in this communication allows the drawing of the following important conclusions: (i) no direct link exists between the antioxidant activity of each isomer/derivative and proapoptotic potency, (ii) tocotrienols are more effective proapoptotic agents than tocopherols, (iii) synthetic modifications of the naturally occurring compounds may improve their apoptotic potency and (iv) vitamin E isomers and derivatives regulate caspase-independent pathways of apoptosis. The latter combined with the evidence presented in this review regarding the additive or synergistic anticarcinogenic effects obtained when vitamin E analogs are used in combination with other cancer chemotherapeutic agents, supports further research to design the most promising vitamin E derivatives and clinically test them in adjuvant chemotherapeutic treatments. © 2008 Wiley-Liss, Inc.

A Low-Cost Sensor Network for Real-Time Monitoring and Contamination Detection in Drinking Water Distribution Systems

Abstract: This paper presents a low cost and holistic approach to the water quality monitoring problem for drinking water distribution systems as well as for consumer sites. Our approach is based on the development of low cost sensor nodes for real time and in-pipe monitoring and assessment of water quality on the fly. The main sensor node consists of several in-pipe electrochemical and optical sensors and emphasis is given on low cost, lightweight implementation, and reliable long time operation. Such implementation is suitable for large scale deployments enabling a sensor network approach for providing spatiotemporally rich data to water consumers, water companies, and authorities. Extensive literature and market research are performed to identify low cost sensors that can reliably monitor several parameters, which can be used to infer the water quality. Based on selected parameters, a sensor array is developed along with several microsystems for analog signal conditioning, processing, logging, and remote presentation of data. Finally, algorithms for fusing online multisensor measurements at local level are developed to assess the water contamination risk. Experiments are performed to evaluate and validate these algorithms on intentional contamination events of various concentrations of escherichia coli bacteria and heavy metals (arsenic). Experimental results indicate that this inexpensive system is capable of detecting these high impact contaminants at fairly low concentrations. The results demonstrate that this system satisfies the online, in-pipe, low deployment-operation cost, and good detection accuracy criteria of an ideal early warning system.

The development of mental processing: efficiency, working memory, and thinking.

Abstract: This Monograph aims to contribute to the information processing, the differential, and the developmental modeling of the mind, and to work these into an integrated theory. Toward this aim, a longitudinal study is presented that investigates the relations between processing efficiency, working memory, and problem solving from the age of 8 years to to the age of 16 years. The study involved 113 participants, about equally drawn among 8-, 10-, 12-, and 14-year-olds at the first testing; these participants were tested two more times spaced one year apart. Participants were tested with a large array of tasks addressed to processing efficiency (i.e., speed of processing and inhibition), working memory (in terms of Baddeley's model, phonological storage, visual storage, and the central executive of working memory), and problem solving (quantitative, spatial, and verbal reasoning). Confirmatory factor analysis validated the presence of each of the above dimensions and indicated that they are organized in a three-stratum hierarchy. The first stratum includes all of the individual dimensions mentioned above. These dimensions are organized, at the second stratum, in three constructs: processing efficiency, working memory, and problem solving. Finally, all second-order constructs are strongly related to a third-order general factor. This structure was stable in time. Structural equation modeling indicated that the various dimensions are interrelated in a cascade fashion so that more fundamental dimensions are part of more complex dimensions. That is, speed of processing is the most important aspect of processing efficiency, and it perfectly relates to the condition of inhibition, indicating that the more efficient one is in stimulus encoding and identification, the more efficient one is in inhibition. In turn, processing efficiency is strongly related to the condition of executive processes in working memory, which, in turn, is related to the condition of the two modality-specific stores (phonological and visual). Finally, problem solving is related to processing efficiency and working memory, the central executive in particular. All dimensions appear to change systematically with time. Growth modeling suggested that there are significant individual differences in attainment in each of the three aspects of the mind investigated. Moreover, each of the three aspects of the mind as well as their interrelations change differently during development. Mixture growth modeling suggested that there are four types of developing persons, each defined by a different combination of performance in these aspects of the mind. Some types are more efficient and stable developers than others. These analyses indicated that processing efficiency is a factor closely associated with developmental differences in problem solving, whereas working memory is associated with individual differences. Modeling by logistic equations uncovered the rates and form of change in the various dimensions and their reciprocal interactions during development. These findings are discussed from the point of view of information processing, differential, and developmental models of thinking, and an integrative model is proposed.

Fetal-specific DNA methylation ratio permits noninvasive prenatal diagnosis of trisomy 21.

Abstract: The trials performed worldwide toward noninvasive prenatal diagnosis (NIPD) of Down's syndrome (or trisomy 21) have shown the commercial and medical potential of NIPD compared to the currently used invasive prenatal diagnostic procedures. Extensive investigation of methylation differences between the mother and the fetus has led to the identification of differentially methylated regions (DMRs). In this study, we present a strategy using the methylated DNA immunoprecipitation (MeDiP) methodology in combination with real-time quantitative PCR (qPCR) to achieve fetal chromosome dosage assessment, which can be performed noninvasively through the analysis of fetal-specific DMRs. We achieved noninvasive prenatal detection of trisomy 21 by determining the methylation ratio of normal and trisomy 21 cases for each tested fetal-specific DMR present in maternal peripheral blood, followed by further statistical analysis. The application of this fetal-specific methylation ratio approach provided correct diagnosis of 14 trisomy 21 and 26 normal cases.