Power limits for secondary devices operating on TV white spaces

The use of TV white spaces as an alternative to overcome spectrum scarcity is a huge opportunity for new telecommunication systems and services. While being attractive for its desirable propagation characteristics, this part of the spectrum imposes a major difficulty from design and regulatory perspectives: how to optimize the use of spectrum and to ensure the protection of primary users, TV systems for example, at the same time. This paper discusses strategies to be adopted by geo-location database operators to calculate adaptive maximum permitted power levels for secondary devices, according to permissible levels of interference into the digital terrestrial television primary system.     

Wireless LANs: From WarChalking to Open Access Networks

This work discusses the evolution of W-LANs from their current status of wireless termination of LAN services to a possible global infrastructure where the access networks become open to multiple operators and a vehicle of a win-win scenario, where both users and operators benefit from the new network architecture. The idea of Open Access Networks (OANs) can go beyond wireless HotSpots and be generalized to a generic shared access infrastructure that fosters service operators competition and drastically reduces the cost of last mile coverage.The general concept of Open Access Networks is detailed, highlighting its difference with the more traditional model of vertical integration of the access network into the global service. About the OANs development, it is shown how to support the quick and smooth evolution of the infrastructure toward a widespread and reliable communication support.Business models are discussed by mentioning the different actors, the market organization and the different organization forms.The final part of the paper is devoted to technical challenges such as access control, security, privacy, roaming, resource exploitation and service differentiation. As an example of how to tackle these problems, we discuss a pricing technique devoted to resource management and billing support.In addition we present a simulation on how the OAN concept can speed-up the deployment of broadband access in a real case.A preliminary version of this paper with the title “Global Growth of Open Access Networks: from WarChalking and Connection Sharing to Sustainable Business” was presented at WMASH 2003. Roberto Battiti received the Laurea degree from the University of Trento, Italy, in 1985 and the Ph.D. degree from the California Institute of Technology (Caltech), USA, in 1990. He has been a consultant in the area of parallel computing and pattern recognition and since 1991 he has been a faculty member at the University of Trento, where he is now full professor of Computer Networks. His main research interests are heuristic algorithms for optimization problems, in particular reactive search algorithms for maximum clique, maximum satisfiability, graph coloring, networks and massively parallel architectures, code assignment in wireless and cellular networks, protocols for pricing and Quality of Service in wireless networks.Prof. R. Battiti is currently Dean of the international Graduate School in Information and Communication Technologies at Trento, Deputy Dean at the Faculty of Science, member of the advisory committee for the future Telecommunications Plan of the Autonomous Province of Trento. Prof. R. Battiti is associate editor of various scientific journals. He is the author of more than fifty scientific publications, including special issues dedicated to experimental algorithmics and wireless on-demand networks.R. Battiti is a member of IEEE Computer Society and ACM Sigmobile. Renato Lo Cigno is Associate Professor at the Department of Computer Science and Telecommunications (DIT) of the University of Trento, Italy. He received a Dr. Ing. degree in Electronic Engineering from Politecnico di Torino in 1988. From 1989 to 2002 has been with the Telecommunication Research Group of the Electronics Department of Politecnico di Torino.From June 1998 to February 1999, he was at the CS Department at UCLA as Visiting Scholar under grant CNR 203.15.8. He is coauthor of more than 90 journal and conference papers in the area of communication networks and systems. His curent research interests are in performance evaluation of wired and wireless networks, modeling and simulation techniques, flow and congestion control, as well as network management and architecture. Renato Lo Cigno is member of the IEEE Communication Society and ACM Sigcomm. Mikalai Sabel received his master degree in radio physics from Belorussian State University in 2002. He is now pursuing his Ph.D. at the international Graduate School of Information and Communication Technologies at University of Trento, Italy. His research interest include wireless LANs, pricing and incentive engineering, IEEE802.11 MAC protocol. His current research is focused on optimization algorithms that can provide stability and maximum global welfare in a non-cooperative environment where singles tries to maximize their own benefit function. Experimentation of such schemes to pricing techniques and micro-payments in TLC networks provides the application environment of the fundamental research. Fredrik Orava is associate professor at KTH, Stockholm, Sweden. He conducts research into scalable (in terms of cost, capacity, number of users and devices etc.) communication system architectures and technologies. He has a MSc in engineering physics from Uppsala University and a PhD in computer systems also from Uppsala University. He previously held positions as researcher at the Swedish Institute for Computer Science (SICS); senior lecturer and manager of the telecommunications systems laboratory at the department for teleinformatics, KTH; acting professor in telecomunication systems at KTH; director for the Swedish Centre for Internet Technologies; and vice president of Dynarc AB with world wide responsibility for product management. Dynarc AB develops, manufactures and sells IP routers for optical IP networks. Bjorn Pehrson is a professor of telecommunication systems at KTH, the Royal Institute of Technology in Stockholm, since 1992, where he has also served as a department chairman and vice dean. He had his PhD from Uppsala University 1975 where he also served as senior lecturer and established a research group in computer and communication technology. During the period 1985-1992 he participated in the establishment of the Swedish Institute of Computer Science. Björn Pehrson research interests are currently focussed on open network topologies allowing different actors forming new value chains to build networks together based on different, sometimes very local business models. The results are applied in testbeds, especially in rural areas and in developing countries.This revised version was published online in August 2005 with a corrected cover date.     

The normal spectral emittance of erbium,dysprosium and samarium above 1000 K

An apparatus for measuring the normal spectral emittance (λ = 0.645 μ.) of metals with very high vapor pressures has been designed and used for erbium, dysprosium and samarium at temperatures above 1000 K. The samples are maintained in an argon atmosphere at a pressure slightly above atmospheric pressure. The measured normal spectral emittances are: Erbium, (solid), ∈ _nλ = 0.372 ± 0.011; (liquid), ∈ _nλ = 0.372 ± 0.011; Dysprosium, (solid), ∈ _nλ = 0.631 – 1.889 × 10^–4 T (deg K); (liquid), ∈ _nλ = 0.297 ± 0.088; Samarium, (solid), ∈ _nλ = 0.437 ± 0.030; (liquid, estimated), ∈ _nλ = 0.437 ± 0.03. TERRY S. KING, formerly Undergraduate Research Helper. DORAB N. BARIA, formerly NSF Presidential Intern and Post-Doctoral Fellow. Prepared for the Energy Research and Development Administration under Contract No. W-7405-eng-82.     

Comparison of bioactive phytochemical content and release of isothiocyanates in selected brassica sprouts

The consumption of brassica sprouts as raw vegetables provides a fair amount of glucosinolates (GLs) and active plant myrosinase, which enables the breakdown of GLs into health-promoting isothiocyanates (ITCs). This study reports the determination of the main constituents related to human health found in edible sprouts of two Brassica oleracea varieties, broccoli and Tuscan black kale, and two Raphanus sativus varieties, Daikon and Sango. Radish sprouts exhibited the highest ability to produce ITCs, with Daikon showing the greatest level of conversion of GLs into bioactive ITCs (96.5%), followed by Sango (90.0%). Tuscan black kale gave a value of 68.5%, whereas broccoli displayed the lowest with 18.7%. ITCs were not the exclusive GL breakdown products in the two B. oleracea varieties, since nitriles were also produced, thus accounting for the lower conversion observed. Measuring the release of plant ITCs is a valuable tool in predicting the potential level of exposure to these bioactive compounds after the consumption of raw brassica sprouts.     

Identification and analysis of isothiocyanates and new acylated anthocyanins in the juice of Raphanus sativus cv. Sango sprouts

The freeze-dried sprouts’ juice of Raphanus sativus (L.) cv. Sango was prepared and analysed for the first time. HPLC analysis of total isothiocyanates, after protein displacement, resulted in 77.8 ± 3.0 μmol/g of dry juice while GC–MS analysis of hexane and acetone extracts showed E- and Z-raphasatin (8.9 and 0.11 μmol/g, respectively) and sulforaphene (11.7 μmol/g), summing up to 20.7 ± 1.7 μmol/g of free isothiocyanates. Sprouts’ juice contained an unprecedented wealth of anthocyanins and a new fractionation methodology allowed us to isolate 34 mg/g of acylated anthocyanins (28.3 ± 1.9 μmol/g), belonging selectively to the cyanidin family. Analysis was performed by HPLC–PDA–ESI–MSⁿ and extended to deacylated anthocyanins and aglycones, obtained, respectively, by alkaline and acid hydrolysis. This study identified 70 anthocyanins, 19 of which have never been described before and 32 of which are reported here in R. sativus for the first time. Sango radish sprouts are exceptional dietary sources of heath-promoting micronutrients.     

Quantitative determination of physical and chemical measurands in honey by near-infrared spectrometry

Fourier transform near-infrared spectroscopy (FT-NIR) was evaluated to quantitatively determine 24 different measurands in honey. The reference values of 421 honey samples of different botanical origins were determined by classical physical and chemical methods. Partial least squares regression was used to develop the calibration models for the measurands studied. These calibrations were then validated using independent samples and proved satisfying accuracies for the determination of water (standard error of prediction: 0.3 g/100 g), glucose (1.3 g/100 g), fructose (1.6 g/100 g), sucrose (0.4 g/100 g), total monosaccharide content (2.6 g/100 g) as well as fructose/glucose ratio (0.09) and glucose/water ratio (0.12). The prediction accuracy for hydroxymethylfurfural, proline, pH-value, electrical conductivity, free acidity and the minor sugars maltose, turanose, nigerose, erlose, trehalose, isomaltose, kojibiose, melezitose, raffinose, gentiobiose, melibiose, maltotriose was poor and unreliable. The results demonstrate that near-infrared spectrometry is a valuable, rapid and non-destructive tool for the quantitative analysis of some measurands related to the main components in honey.     

Determination of catechins in green tea infusions by reduced flow micellar electrokinetic chromatography

A sulfated-β-cyclodextrin (s-β-CD) modified reduced flow micellar electrokinetic chromatography (RF-MEKC) method was developed and validated for the determination of catechins in green tea. The optimal electrolyte consisted of 0.2% triethylamine, 50 mmol/L SDS and 0.8% s-β-CD (pH = 2.9), allowing baseline separation of five catechins in 4 min. The samples and standards were injected at 0.6 psi for 5 s under constant voltage of −30 kV. Sample preparation simply involved extraction of 2 g of tea with 200 mL water at 95 °C under constant stirring for 5 min. The method demonstrated excellent performance, with limits of detection (LOD) and quantification (LOQ) of 0.02–0.1 and 0.1–0.5 μg/mL, respectively, and recovery percentages of 94–101%. The method was applied to six samples of Brazilian green tea infusions. Epigallocatechin gallate (23.4–112.4 μg/mL) was the major component, followed by epigallocatechin (18.4–78.9 μg/mL), epicatechin gallate (5.6–29.6 μg/mL), epicatechin (4.6–14.5 μg/mL) and catechin (3.2–8.2 μg/mL).     

Zinc Oxide Nanoparticles: Synthesis,Antimicrobial Activity and Food Packaging Applications

Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are also discussed.