Generation of spatio-temporal concentration profiles for cell culture systems: A case study in ammonia

Cellular behavior is influenced by micro-concentration gradients existing in their immediate spatio-environment. A practical real-time measurement system, composed of miniaturized long-lasting sensors placed within a two-dimensional bioreactor and a 32-channel data acquisition system for ammonia, is presented in this paper aiming to generate the spatio-temporal ammonia concentration profiles for the whole culture process. Our results demonstrate the feasibility of the system and its applicability in elucidating the cell growth micro-environment within a bioreactor, which can potentially facilitate the intelligent control of ammonia levels in cell culture systems. The presented system is flexible enough to interface other sensors for generating their spatio-temporal profiles of the sensed cell culture parameters.     

Cloud-assisted body area networks: state-of-the-art and future challenges

Body area networks (BANs) are emerging as enabling technology for many human-centered application domains such as health-care, sport, fitness, wellness, ergonomics, emergency, safety, security, and sociality. A BAN, which basically consists of wireless wearable sensor nodes usually coordinated by a static or mobile device, is mainly exploited to monitor single assisted livings. Data generated by a BAN can be processed in real-time by the BAN coordinator and/or transmitted to a server-side for online/offline processing and long-term storing. A network of BANs worn by a community of people produces large amount of contextual data that require a scalable and efficient approach for elaboration and storage. Cloud computing can provide a flexible storage and processing infrastructure to perform both online and offline analysis of body sensor data streams. In this paper, we motivate the introduction of Cloud-assisted BANs along with the main challenges that need to be addressed for their development and management. The current state-of-the-art is overviewed and framed according to the main requirements for effective Cloud-assisted BAN architectures. Finally, relevant open research issues in terms of efficiency, scalability, security, interoperability, prototyping, dynamic deployment and management, are discussed.     

An adaptive and efficient buffer management scheme for resource-constrained delay tolerant networks

Provisioning buffer management mechanism is especially crucial in resource-constrained delay tolerant networks (DTNs) as maximum data delivery ratio with minimum overhead is expected in highly congested environments. However, most DTN protocols do not consider resource limitations (e.g., buffer, bandwidth) and hence, results in performance degradation. To strangle and mitigate the impact of frequent buffer overflows, this paper presents an adaptive and efficient buffer management scheme called size-aware drop (SAD) that strives to improve buffer utilization and avoid unnecessary message drops. To improve data delivery ratio, SAD exactly determines the requirement based on differential of newly arrived message(s) and available space. To vacate inevitable space from a congested buffer, SAD strives to avoid redundant message drops and deliberate to pick and discard most appropriate message(s) to minimize overhead. The performance of SAD is validated through extensive simulations in realistic environments (i.e., resource-constrained and congested) with different mobility models (i.e., Random Waypoint and disaster). Simulation results demonstrate the performance supremacy of SAD in terms of delivery probability and overhead ratio besides other metrics when compared to contemporary schemes based on Epidemic (DOA and DLA) and PRoPHET (SHLI and MOFO).     

High resolution melting analysis for quantitative detection of bovine milk in pure water buffalo mozzarella and other buffalo dairy products

Identification of buffalo dairy products has become an important issue to ascertain product quality, consumer rights and absence of food-borne allergic reactions. A polymerase chain reaction (PCR) followed by a high resolution melting (HRM) analysis was developed and applied for species specific detection of bovine milk in nine different commercial buffalo dairy products. A specific buffalo 12S rRNA and a bovine d-loop primer pair, targeting the mitochondrial genome, were employed in a duplex PCR assay. The analysis developed was found capable of identifying the presence of bovine milk down to 1% in commercial buffalo milk products and also of quantifying the ratio of bovine into buffalo milk. HRM was proven to be a fast and accurate technique for a routine authentication testing of mozzarella and other buffalo milk products.     

Critical Behavior in the Low-Energy Spin Fluctuations in High-Tc Superconductors

We study the spin fluctuations of pure and Zn-substituted La_{2 – x} Sr _x CuO₄ using the muon spin relaxation technique. Superconductivity is found to coexist with low-frequency spin fluctuations over a large region of the superconducting phase diagram. The characteristic temperature of spin fluctuations detected by SR decreases with increasing x and vanishes above a critical doping x _c 0.19. This value of x _c coincides with the doping at which the normal state pseudogap extrapolates to zero. These results are discussed in terms of a quantum transition that separates the superconducting phase diagram of high-temperature superconductors into two distinct ground states.     

Causal ordering of physical self-concept and exercise behavior: Reciprocal effects model and the influence of physical education teachers.

Does prior physical self-concept influence subsequent exercise behavior? On the basis of a large sample of physical education classes (2,786 students, 200 classes, 67 teachers) collected early (Time 1) and late (Time 2) in the school year, findings support a reciprocal effects model in which prior physical self-concept and exercise behavior both influence subsequent physical self-concept and exercise behavior. Whereas variables from the theory of planned behavior (TOPB; behavioral intentions, perceived behavioral control, exercise attitudes) also contributed to the prediction of subsequent exercise behavior, the effect of prior physical self-concept was significant for subsequent outcomes after controlling these variables, suggesting that the TOPB should be supplemented with self-concept measures. On the basis of multilevel models, there were systematic differences in these variables for students taught by different teachers that generalized over time and across different classes taught by the same teacher. Support for the reciprocal effects model was robust. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MIMO Channel Characterization for Short Range Fixed Wireless Propagation Environments

This paper reports results from wideband MIMO measurements performed in short range fixed wireless environments at 5.2 GHz. The objective is to provide MIMO channel characterization results for the measured environments and contribute to the limited available similar studies. Two kinds of propagation scenarios are investigated, rooftop to rooftop and street to rooftop, at three different sites always under LOS propagation conditions. The analysis of measurement data is performed in the context of non physical modeling, providing insight into the statistics of the measured channels. In particular, the slow time varying nature of the channel is studied and the narrow Doppler spectrum shape is approximated. Furthermore, frequency correlation results are obtained and the typical delay dispersion measures are extracted. Then, the antenna correlation is studied and the error of the Kronecker product approximation is evaluated. Finally, capacity results are provided and the channel measurements are characterized in terms of spatial multiplexing quality and multipath richness through condition number analysis. Nikolaos D. Skentos received his Diploma in Electrical and Computer Engineering from the National Technical University of Athens (NTUA), Greece in October 2000. Since January 2001 he has been a research associate at the Mobile Radio Communications Laboratory at the NTUA, and he is currently working towards the Ph.D. degree. His research interests include channel measurements, MIMO channel characterization, MIMO algorithms and space time processing. He has been active in the IST STINGRAY project, the COST 273 Action and the ACE Network of Excellence. He is also a member of the National Technical Chamber of Greece since 2001. Athanasios G. Kanatas received the Diploma in Electrical Engineering from the National Technical University of Athens, Greece, in 1991, the M.Sc. degree in Satellite Communication Engineering from the University of Surrey, Surrey, UK in 1992, and the Ph.D. degree in Mobile Satellite Communications from the National Technical University of Athens, Greece in February 1997. From 1993 to 1994 he was with National Documentation Center of National Research Institute. In 1995 he joined SPACETEC Ltd. where he was Technical Project Manager for VISA/EMEA VSAT Project in Greece. In 1996 he joined the Mobile Radio Communications Laboratory as a research associate. From 1999 to 2002 he was with the Institute of Communication & Computer Systems. In 2000 he became a member of the Board of Directors of OTESAT S.A. He is an Assistant Professor in the Department of Technology Education and Digital Systems at University of Piraeus. His current research interests include channel characterization and estimation, simulation and modeling for mobile, mobile satellite, and future wireless communication systems. He has been a Senior Member of IEEE since 2002, and is also a member of the Technical Chamber of Greece. In 1999 he was elected Chairman of the Communications Society of the Greek IEEE Section. Panagiotis I. Dallas was born 1967 in Thessaloniki, Greece. He obtained his diploma and Ph.D. degree from the Electrical and Computer Engineering Department of Aristotle University of Thessaloniki, Greece, in 1990 and 1997, respectively. Since 1998 he joined with INTRACOM where he currently is Section Manager of Advanced Communications Technologies branch of Emerging Technologies & Markets department, leading the next generation of broadband wireless access systems for internal and EU projects. He runs the relevant standardization activities (IEEE 802.16 and ETSI/BRAN HIPERMAN) in INTRACOM and he represents the company in WiMAX forum. Finally, he has over 30 publications in international journals and conferences. Philip Constantinou received the Diploma in Physics from the National University of Athens in 1972, the Master of Applied Science in Electrical Engineering from the University of Ottawa, Ontario, Canada in 1976, and the Ph.D. degree in Electrical Engineering in 1983 from Carleton University, Ottawa, Ontario, Canada. From 1976 to 1979 he was with Telesat Canada as a Communications System Engineer. In 1980 he joined the Ministry of Communications in Ottawa, Canada where he was engaged in the area of Mobile Communication. From 1984 to 1989 he was with the National Research Center Demokritos in Athens, Greece where he was involved in several research projects in the area of Mobile Communications. In 1989 he joined the National Technical University of Athens where he is currently a Professor and Director of the Mobile Radio Communications Laboratory. His current research interests include Personal Communications, Mobile Satellite Communications, and Interference Problems on Digital Communications Systems.     

ON THE ACCURATE MODELING OF MILLIMETER WAVE FIXED WIRELESS CHANNELS EXCEEDANCE PROBABILITY

The ever increasing demand for high date rate multimedia services has led to the deployment of Fixed Wireless Access (FWA) networks operating in frequencies above 10GHz. Propagation characteristics of such networks include line-of-sight (LOS) transmissions highly influenced by the presence of rain. In this paper a methodology for evaluating the outage probability of a FWA channel is introduced, making use of the forward scattering amplitude by distorted raindrops of transmitted signals. Expressions for the imaginary part of the scattering amplitude are derived through a regression fitting analysis on the results of the Method of Auxiliary Sources (MAS) to the problem of electromagnetic scattering from a Pruppacher-Pitter raindrop. These expressions are employed and an analytical method to evaluate the rain attenuation exceedance probability over a fixed wireless access link is presented. The derived exceedance probabilities are compared with experimental data from ITU-R databank with encouraging results.