Evolving access networks: a European perspective

The diversity of telecommunications markets and access network infrastructure among the countries of Europe is a complicating factor in the development of effective standards for Europe's future access networks. The need for evolving access networks to make efficient use of a wide variety of existing infrastructure may at times conflict with the long-term requirement for a stable platform of self-consistent standards which allow future-proof evolution. In light of these constraints, the authors summarize progress made in the European Telecommunications Standards Institute (ETSI) toward standards for future access networks     

The Contribution of Vessel Volume Change and Blood Resistivity Change to the Electrical Impedance Pulse

An impedance pulse, recorded noninvasively, has contributions due to both the change in blood volume of the arteries and to the change in the blood resistivity. Other researchers have tried to quantify the relative contributions and have either underestimated or overestimated the contributions since they did not simulate the physiological conditions. We have used an in vitro flow circulation system to more closely simulate the physiological conditions and quantify the two contributions. We find that the blood resistivity change contribution is strong enough (21.5 percent of the arterial volume change contribution) to change the morphology of the impedance pulse. There is, however, a phase difference between the two contributions. As a result of this, the blood resistivity change contribution to the height of the impedance pulse will be less than 5.5 percent.     

Engineering Properties of Sand-Fiber Mixtures for Road Construction

The purpose of this investigation was to identify and quantify the effect of numerous variables on the performance of fiber-stabilized sand specimens. Laboratory unconfined compression tests were conducted on sand specimens reinforced with randomly oriented discrete fibers to isolate the effect of each variable on the performance of the fiber-reinforced material. Five primary conclusions were obtained from this investigation. First, the inclusion of randomly oriented discrete fibers significantly improved the unconfined compressive strength of sands. Second, an optimum fiber length of 51 mm (2 in.) was identified for the reinforcement of sand specimens. Third, a maximum performance was achieved at a fiber dosage rate between 0.6 and 1.0% dry weight. Fourth, specimen performance was enhanced in both wet and dry of optimum conditions. Finally, the inclusion of up to 8% of silt does not affect the performance of the fiber reinforcement.     

Low-distortion MMIC power amplifier using a new form of derivativesuperposition

Reduction of interchannel interference produced by a power amplifier near 1-dB compression is a key concern for the wireless communications industry. In this paper, we present a 100-mW monolithic-microwave integrated-circuit (MMIC) power amplifier designed using a novel form of the derivative superposition method. The measured results of the MMIC power amplifier showed a two-tone carrier-to-interference (C/I) ratio of 45 dBc with an efficiency of 22.5% when backed off by 4.5 dB from the 1-dB compression point. We demonstrate that the MMIC power amplifier represents a good compromise between C/I ratio, output power, efficiency, and gain at the cost of an increase in total gate width, by comparing it to class-A, class-AB, and class-B single field-effect-transistor amplifiers     

Preparation and Anti-Tumour Activity of Some Arylbismuth(III) Oxine Complexes.

New arylbismuth(lll) oxinates, PhBi(MeOx)(2), (p-MeC(6)H(4))Bi(Ox)(2), (p-MeC(6)H(4))Bi(MeOx)(2), (p-ClC(6)H(4))Bi(Ox)(2), and (p-ClC(6)H(4))Bi(MeOx)(2) (Ox(-) = quinolin-8-olate and MeOx(-)=2-methylquinolin-8-olate) have been prepared by reaction of the appropriate diarylbismuth chlorides with Na(Ox) or Na(MeOx) in the presence of 15-crown-5. An X-ray crystallographic study has shown PhBi(MeOx)(2) to be a five coordinate monomer with distorted square pyramidal stereochemistry. Chelating MeOx ligands have a cisoid arrangement in the square plane and the phenyl group is apical. The lattice is stabilised by significant pi-pi interactions between centrosymmetric molecules. A range of these complexes has been shown to have high in vitro biological activity (comparable with or better than cisplatin) against L1210 leukaemia, the corresponding cisplatin resistant line, and a human ovarian cell line, SKOV-3. However, initial in vivo testing against a solid mouse plasmacytoma (PC6) and P388 leukaemia has not revealed significant activity.     

Influence of raised floor on zone design cooling load in commercial buildings

The installation of a raised floor system can change the thermal behaviour of the building by reducing the interaction between the heat gains and the thermally massive concrete slab. In this study, the influence of the raised floor on the summer design day zone cooling load profile is evaluated with EnergyPlus for an office building located in San Francisco. The effects of structure type, window-to-wall ratio and the presence of carpet on the thermal behaviour of the raised floor are also investigated. The results show that the mere presence of the raised floor largely affects the zone cooling load profile and the peak cooling load over the range of −7 to +40%. The most significant parameters are the zone orientation, i.e. the exposure to direct solar radiation, and the presence of floor carpeting. If carpeting is present, commonly used in U.S. office buildings, the overall impact on zone peak cooling load is reduced, ranging from 0 to 5% greater for the raised floor than without it. Without carpet the peak cooling load is 4% greater with raised floor than without it in the north zone, 22% in the east and west zones, and 12% in the south zone.     

Role of fuel carbon intensity in achieving 2050 greenhouse gas reduction goals within the light-duty vehicle sector

Recent U.S. climate change policy developments include aggressive proposals to reduce greenhouse gas emissions, including cap-and-trade legislation with a goal of an 83% reduction below 2005 levels by 2050. This study examines behavioral and technological changes required to achieve this reduction within the light-duty vehicle (LDV) sector. Under this "fair share" sectoral assumption, aggressive near-term actions are necessary in three areas: vehicle miles traveled (VMT), vehicle fuel economy (FE), and fuel carbon intensity (FCI). Two generic scenarios demonstrate the important role of FCI in meeting the 2050 goal. The first scenario allows deep reductions in FCI to compensate for relatively modest FE improvements and VMT reductions. The second scenario assumes optimistic improvements in FE, relatively large reductions in VMT and less aggressive FCI reductions. Each generic scenario is expanded into three illustrative scenarios to explore the theoretical implications of meeting the 2050 goal by relying exclusively on biofuels and hybrid vehicles, biofuels and plug-in hybrid vehicles, or hydrogen fuel cell electric vehicles. These scenarios inform a discussion of resource limitations, technology development and deployment challenges, and policy goals required to meet the 2050 GHG goal for LDVs.     

Fate of endogenous steroid hormones in steer feedlots under simulated rainfall-induced runoff

Steroid hormones pose potential risks to fish and other aquatic organisms at extremely low concentrations. To assess the factors affecting the release of endogenous estrogenic and androgenic steroids from feedlots during rainfall, runoff, and soil samples were collected after simulated rainfall on a 14-steer feedlot under different rainfall rates and aging periods and analyzed for six steroid hormones. While only 17α-estradiol, testosterone, and progesterone were detected in fresh manure, 17β-estradiol, estrone, and androstenedione were present in the surficial soil after two weeks. In the feedlot surficial soil, concentrations of 17α-estradiol decreased by approximately 25% accompanied by an equivalent increase in estrone and 17β-estradiol. Aging of the feedlot soils for an additional 7 days had no effect on estrogen and testosterone concentrations, but androstenedione concentrations decreased substantially, and progesterone concentrations increased. Androstenedione and progesterone concentrations in the surficial soil were much higher than could be accounted for by excretion or conversion from testosterone, suggesting that other potential precursors, such as sterols, were converted after excretion. The concentration of androgens and progesterone in the soil were approximately 85% lower after simulated rainfall, but the estrogen concentrations remained approximately constant. The decreased masses could not be accounted for by runoff, suggesting the possibility of rapid microbial transformation upon wetting. All six steroids in the runoff, with the exception of 17β-estradiol, were detected in both the filtered and particle-associated phases at concentrations well above thresholds for biological responses. Runoff from the aged plots contained less 17α-estradiol and testosterone, but more estrone, androstenedione, and progesterone relative to the runoff from the unaged plots, and most of the steroids had a lower particle-associated fraction.     

Preliminary investigation of the impact of polymer composition on electrochemical properties of coatings as determined by electrochemical impedance spectroscopy

The influence of structural and systematic compositional variations in glycidyl carbamate (GC) functional polymers on the electrochemical properties of their coatings was studied. There are few reports which focus on the correlation of structural and compositional variations in polymer films with their electrochemical barrier properties, diffusion properties with regards to water and aqueous electrolytes, and corrosion performance. To begin to fill this knowledge gap, two sets of GC functional polymers were studied. The polymer compositions were designed to vary the extent of polar hydrophilic groups, non-polar hydrophobic groups, and reactive epoxy groups in the final coatings. Impedance responses of the coatings were found to be closely related to the structural and compositional variations of these GC polymer films. In addition, single frequency EIS experiments were used in an attempt to understand the water uptake behavior of these polymer films using NaCl solution and ionic liquid under immersed condition. The resulting transport property data of the films was correlated to their polymer structure and composition. Moreover, a novel attempt at ranking the stability of coating using capacitance measurement during a cyclic wetting–drying condition was also attempted. The information obtained from this work can potentially be used to optimize the polymer for the specific performance properties needed in the protective coating applications, saving significant time and effort in the research and development stage.