Guest Editorial: Selected Papers on Wireless and Mobility from IEEE INFOCOM

The three papers in this special section were originally presented at the IEEE INFOCOM 2006 conference in Barcelona. The augmented papers, which address issues in wireless networks and mobile computing, represent the high quality of research presented at the conference.     

Conflict and Cooperation on International Rivers: The Case of the Colorado River on the US‐Mexico Border

This paper describes the work of the International Boundary and Water Commission, United States and Mexico (IBWC), to find cooperative solutions to issues pertaining to the Colorado River along the US-Mexico border. Since 1944, the IBWC has worked to resolve issues related to the distribution of the waters of the Colorado River between the United States and Mexico; salinity of waters delivered to Mexico; conveyance capacity of the Colorado River; and the conditions of the Colorado River Delta. The IBWC has emphasized binational cooperation to explore both short-term and long-term solutions to these issues.     

Changes in quality and phenolic compounds of virgin olive oils during objectively described fruit maturation

The effect of fruit ripening on the quality of the oil extracted and on the changes in the amount of phenolic compounds was determined in two olive varieties (Olea europaea, cvs. Arbequina and Picual) in two crop seasons, characterized by showing the same mean temperature and different rainfalls. Maturation level was evaluated using six methods: Harvest date, ripening index (RI), fruit skin colour, fruit firmness, and amount of chlorophylls and carotenoids in the oil. Oil quality, evaluated using the parameters established to determine the quality level of virgin olive oils (acidity, K₂₃₂, K₂₇₀, peroxide index, and panel test), was not affected by fruit ripening or by the increase in rainfall of the season. However, the changes in oil stability and phenolic compounds in the oils extracted during fruit ripening strongly differed according to the variety, the maturity level of the fruit and the crop season tested. Fruit skin colour and firmness allowed a better discrimination at the initial maturity stages than the other methods tested.     

Developing an Irreversible Inhibitor of Human DDAH‐1, an Enzyme Upregulated in Melanoma

Inhibitors of the human enzyme dimethylarginine dimethylaminohydrolase‐1 (DDAH‐1) can raise endogenous levels of asymmetric dimethylarginine (ADMA) and lead to a subsequent inhibition of nitric oxide synthesis. In this study, N⁵‐(1‐imino‐2‐chloroethyl)‐L ‐ornithine (Cl‐NIO) is shown to be a potent time‐ and concentration‐dependent inhibitor of purified human DDAH‐1 (K_I=1.3±0.6 μM ; k_inact=0.34±0.07 min^?1), with >500‐fold selectivity against two arginine‐handling enzymes in the same pathway. An activity probe is used to measure the “in cell” IC₅₀ value (6.6±0.2 μM ) for Cl‐NIO inhibition of DDAH‐1 artificially expressed within cultured HEK293T cells. A screen of diverse melanoma cell lines reveals that a striking 50/64 (78 %) of melanoma lines tested showed increased levels of DDAH‐1 relative to normal melanocyte control lines. Treatment of the melanoma A375 cell line with Cl‐NIO shows a subsequent decrease in cellular nitric oxide production. Cl‐NIO is a promising tool for the study of methylarginine‐mediated nitric oxide control and a potential therapeutic lead compound for other indications with elevated nitric oxide production, such as septic shock and idiopathic pulmonary fibrosis.     

Physical basis for the design of CdS/CdTe thin film solar cells

Solar cells based on polycrystalline semiconductor thin films have great potential for decreasing the cost of photovoltaic energy. However, this kind of solar cells has characteristics very different from those fabricated on crystalline silicon for which the carrier-transport and behavior is clearly known. Instead, for hetero-junction solar cells made on less known polycrystalline materials the design is almost empirical. In this work, several physical aspects related to the behavior of polycrystalline thin film solar cells will be discussed, and some considerations for an adequate design of this kind of solar cells will be made. For example, the recombination at the grain boundaries and its influence on the short circuit current as a function of the crystallite sizes on the active material is considered. Based on this, the appropriate thickness of each layer and their resistivity will be discussed. As an example, these considerations will be applied to CdS/CdTe heterojunction solar cells, taking into account typical properties of CdTe thin films used for solar cells.     

Effect of sourdough on quality and acceptability of wheat flour tortillas

As an alternative on the search for functional food products, this study evaluated the use of sourdough in the preparation of wheat flour tortillas. The sourdough was elaborated with Lactobacillus sanfranciscensis and the wheat flour tortillas were prepared with different concentrations of mother sponge (5%, 15%, and 25%) and fermentation times (1 and 3 h) at room temperature (25 ± 2 °C). Quality (diameter, height, color, pH, stretchability scores, and Kramer shear cell results) of wheat tortillas was evaluated after 24 h of preparation. The mother sponge concentration and fermentation time affected some quality parameters and acceptability properties (taste, aroma, color, opacity, and rollability). In addition, the sourdough tortillas had higher stretchability values than control tortillas. Since most of the prepared sourdough tortillas had acceptability values similar to those of tortilla controls, the introduction of sourdough is a viable means to incorporate additional nutritional and nutraceutical value into wheat tortillas.     

Atmospheric-pressure dielectric barrier discharge generation by a full-bridge flying capacitor multilevel inverter

A new configuration of a resonant full-bridge flying capacitor multicell inverter has been designed and constructed with the aim of achieving an extended output voltage frequency range with low harmonic distortion and reduced semiconductor commutation losses. This configuration was tested as a power supply for two different coaxial dielectric barrier discharge reactors, one of them employed for electric characterization and the other one for inorganic compound elimination in an aqueous solution. Two different gas mixtures, 90% Ar–10% O_2 and80% Ar–20% O_2, were individually supplied during the experiments; the results showed a highefficiency removal of meta-cresol(m-cresol) to the order of 98%, which was obtained by adding more oxygen to the plasma gas mixture.     

Iron deficiency enhances bioactive phenolics in lemon juice

BACKGROUND This study was designed to describe the phenolic status of lemon juice obtained from fruits of lemon trees differing in iron (Fe) nutritional status. Three types of Fe(III) compound were used in the experiment, namely a synthetic chelate and two complexes derived from natural polymers of humic and lignine nature. RESULTS All three Fe(III) compounds were able to improve the Fe nutritional status of lemon trees, though to different degrees. This Fe(III) compound effect led to changes in the polyphenol content of lemon juice. Total phenolics were decreased (～33% average decrease) and, in particular, flavanones, flavones and flavonols were affected similarly. CONCLUSION Iron‐deficient trees showed higher phenolic contents than Fe(III) compound‐treated trees, though Fe deficiency had negative effects on the yield and visual quality of fruits. However, from a human nutritional point of view and owing to the health‐beneficial properties of their bioavailable phenolic compounds, the nutritional quality of fruits of Fe‐deficient lemon trees in terms of phenolics was higher than that of fruits of Fe(III) compound‐treated lemon trees. Moreover, diosmetin‐6,8‐di‐C‐glucoside in lemon juice can be used as a marker for correction of Fe deficiency in lemon trees. Copyright © 2011 Society of Chemical Industry     

Performance analysis of the domestic water meter park in water supply network of Ibarra,Ecuador

Apparent losses are one of the most important components of non-revenue water and mainly caused by water meter under-registration. This paper studies the performance of a water meter park from a developing country water utility in Ibarra city, Ecuador. The study includes three major aspects: water meter error curve reconstruction with seven different flow rates; water meter evaluation as a function of class, manufacturer and totalized registered volume, use of two water consumption patterns for weighted error determination and their influence on water balance and performance indicators analysis. Results indicate that 44% of analyzed meters works at optimal conditions. Weighted error obtained by using two different consumption patterns indicates a 0.95% difference, which has an important impact on water balance and performance indicator results. This detailed analysis of water meters can help to develop a more efficient water meter replacement strategy and to estimate apparent water loss volume more accurately.