Close friend and group influence on adolescent cigarette smoking and alcohol use.

The relative influence of adolescents' closest friends and their friendship group on their cigarette smoking and alcohol use was investigated in a short-term, longitudinal study of 1,028 students in the 6th, 8th and 10th grades in 2 school systems. The amount of influence over the school year was modest in magnitude and came from the closest friend for initiation of cigarette and alcohol use. Only the friendship group use predicted transition into current cigarette use, whereas only the close friend use predicted transition into current alcohol use. Both group and close friends independently contributed to the prediction of adolescents' drinking to intoxication. No difference in the amount of influence, was found between stable and unstable close friendships or friendship groups; neither grade nor gender of the adolescents related to the amount of influence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Size distribution of wastewater COD fractions as an index for biodegradability

The study proposes direct particle size measurement by sequential filtration and ultrafiltration as a convenient method for wastewater characterization for appropriate treatment technology. It also explores the correlation between particle size distribution (PSD) and chemical oxygen demand (COD) fractionation, as an index for biological treatability. Profiles obtained through PSD-based COD fractionation serve as the fingerprints for wastewaters, and as demonstrated in this study, reflect different pictures for textile wastewater and domestic sewage. PSD-based COD fractionation profiles identify the soluble range below 2 nm as the size interval housing both the soluble inert COD initially present in the wastewater and soluble inert microbial products generated during biological treatment, as also supported by the metabolic fractionation attained through respirometric analyses. Moreover, PSD-based color profiling offers a good index for the fate of biologically resistant chemicals passing through biological treatment. Compatible results obtained from comparative evaluation of PSD-based COD and color profiles provide useful information on the biodegradability of the textile wastewater studied.     

Sensitivity analysis of submerged arc welding process parameters

Selection of process parameters has great influence on the quality of a welded connection. Mathematical modelling can be utilized in the optimization and control procedure of parameters. Rather than the well-known effects of main process parameters, this study focuses on the sensitivity analysis of parameters and fine tuning requirements of the parameters for optimum weld bead geometry. Changeable process parameters such as welding current, welding voltage and welding speed are used as design variables. The objective function is formed using width, height and penetration of the weld bead. Experimental part of the study is based on three level factorial design of three process parameters. In order to investigate the effects of input (process) parameters on output parameters, which determine the weld bead geometry, a mathematical model is constructed by using multiple curvilinear regression analysis. After carrying out a sensitivity analysis using developed empirical equations, relative effects of input parameters on output parameters are obtained. Effects of all three design parameters on the bead width and bead height show that even small changes in these parameters play an important role in the quality of welding operation. The results also reveal that the penetration is almost non-sensitive to the variations in voltage and speed.     

Maximising low voltage grid hosting capacity for PV and electric mobility by distributed voltage control

European low voltage grids host an increasing amount of energy from rooftop PV installations. Experience in Germany has shown that PV installations do not grow uniformly but with regional hot spots. Meanwhile it is widely agreed that low voltage grids should only be updated to accommodate some 90 % or less of available PV power in peak times in order to avoid extensive costs for grid reinforcement. The main limiting factor in rural distribution grids is the grid voltage. In the Austrian research project “DG DemoNet—Smart LV Grid” new approaches to deal with restricted grid capacities are analysed using active voltage control. In three pilot regions, the actual amount of installed PV is increased to reach physical limits. Voltage control schemes are developed, tested in simulations and then validated in the field. In one pilot region, electric mobility as additional future load in low voltage grids and its integration into the overall system is considered. This paper analyses the performance of the developed control approaches in simulation.     

An analysis of cyclic scheduling problems in robot centered cells

The focus of this study is a robot centered cell consisting of m computer numerical control (CNC) machines producing identical parts. Two pure cycles are singled out and further investigated as prominent cycles in minimizing the cycle time. It has been shown that these two cycles jointly dominate the rest of the pure cycles for a wide range of processing time values. For the remaining region, the worst case performances of these pure cycles are established. The special case of 3-machines is studied extensively in order to provide further insight for the more general case. The situation where the processing times are controllable is analyzed. The proposed pure cycles also dominate the rest when the cycle time and total manufacturing cost objectives are considered simultaneously from a bicriteria optimization point of view. Moreover, they also dominate all of the pure cycles in in-line robotic cells. Finally, the efficient frontier of the 3-machine case with controllable processing times is depicted as an example.     

Secondhand smoke exposure and the risk of hearing loss

Hearing loss has been associated with tobacco smoking, but its relationship with secondhand smoke is not known. We sought to investigate the association between secondhand smoke exposure and hearing loss in a nationally representative sample of adults. The National Health and Nutrition Examination Survey (NHANES), a nationally representative cross-sectional dataset, was utilised to investigate the association between secondhand smoke exposure and hearing loss. Data collected from non-smoking participants aged 20-69 years were included in the analysis if they had completed audiometric testing, had a valid serum continue value, and provided complete smoking, medical co-morbidity and noise exposure histories (N=3307). Hearing loss was assessed from averaged pure-tone thresholds over low- or mid-frequencies (500, 1000 and 2000 Hz) and high-frequencies (3000, 4000, 6000 and 8000 Hz), and was defined as mild or greater severity (pure-tone average in excess of 25 dB HL). Second-Hand Smoke (SHS) exposure was significantly associated with increased risk of hearing loss for low-/mid-frequencies (adjusted OR=1.14; 95% CI 1.02-1.28 for never smokers and 1.30; 1.10-1.54 for former smokers) and high-frequencies (1.40; 1.22-1.81 for former smokers), after controlling for potential confounders. Findings from the present analysis indicate that SHS exposure is associated with hearing loss in non-smoking adults.     

Investigation of the abrasive wear behaviour of ZA-27 alloy and CuSn10 bronze

In this study, abrasive wear behaviours of ZA-27 alloy and CuSn10 bronze were investigated using a purpose-built wear tester. The ZA-27 alloy was produced by permanent mould casting. The abrasive SiC particles having 63 μm grit size was added to the lubricant oil. The wear rate and friction coefficient of alloys were determined at the different test conditions such as sliding distance, applied load, linear velocity and percentage SiC weight content. The wear surfaces of alloys were examined using SEM and EDS analysis. The results showed that the wear rate of alloys decreased with the increasing of applied load and increased with the increasing linear velocity and abrasive SiC content. It was found that the SiC particle fracture was an important mechanism determining the friction and the wear rate of alloys. CuSn10 bronze showed higher wear resistance than ZA-27 alloy under abrasive test conditions except at high linear velocities.     

Differentiation, Conformity, and Construction Firm Performance

Competitive strategy and neo-institutional scholars offer different views for studying a firm’s relationship with its environment. Competitive strategy scholars propose that a firm’s environment hosts competitive forces and that a firm’s performance is closely related with its ability to differentiate itself from its rivals. Neo-institutional scholars, on the other hand, propose that a firm’s environment hosts institutional forces and that a firm’s performance is closely related with its ability to conform to institutional norms. The research presented here builds on the premise that the propositions set forth by competitive strategy and neo-institutional scholars are complementary rather than contradictory. It empirically explores these propositions in the context of the U.S. construction industry. Research findings provide considerable empirical support for the competitive strategy scholars’ proposition that differentiation vis-à-vis rivals is positively related with a firm’s performance. On the other hand, research findings do not provide any empirical support to the neo-institutional scholars’ proposition that conformity to regulatory and societal expectations is positively related to a firm’s performance.