Maternal levels of organochlorines in two communities in southern Vietnam

Some pesticides and PCBs continue to be reported as environmental problems in some areas of Vietnam. In 2005, a study among delivering women took place in two communities in south-central Vietnam (Khanh Hoa Province), namely the coastal city of Nha Trang and the rural district of Dien Khanh located about 10 km inland. The main findings in plasma (n = 189) were relatively high mean concentrations of p,p′-DDE (12.2 µg/l in Nha Trang and 11.4 µg/l in Dien Khanh) and p,p′-DDT (1.2 µg/l in Nha Trang and 1.1 µg/l in Dien Khanh) with no significant community differences. The ratio of p,p′-DDE/p,p′-DDT (11.5 in Nha Trang/12.7 in Dien Khanh) suggests, as in other Vietnamese OCs studies, a relatively recent use of this pesticide. Mean concentrations of PCB 153 (0.15 µg/l in Nha Trang and 0.10 µg/l in Dien Khanh) and other congeners were low in both communities. Age and parity (all compounds), as well as community of residence for PCB 153, were the most important predictors of plasma OCs concentrations.     

Comparative study of distraction versus topical anesthesia for pediatric pain management during immunizations.

This study compared distraction, an anesthetic (eutectic mixture of local anesthetics [EMLA]), and typical care during pediatric immunizations. Participants were 39 4th graders receiving a 3-injection vaccination series over a 6-month period. Children displayed low distress despite reporting moderate anxiety and pain. Distraction resulted in more nurse coaching and child coping and less child distress than did EMLA or typical care on an observational measure. EMLA did not result in increased child coping or decreased distress. In fact, the nurse coached more, and trends suggested that children coped more with typical care than with EMLA. Whereas participant ratings and heart rate did not differ among conditions, all 3 conditions demonstrated improvements over time with these measures. Satisfaction ratings suggested that children preferred the treatments to typical care, whereas the nurse appreciated aspects of each of the conditions. Finally, distraction was more economical than EMLA. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

消除汽车和工业环境中的视频共模噪声

图1中显示的电路能有效地去除在汽车电子应用和工业应用中视频信号的背景噪声(图1).这种特殊的设计可使共模噪声降低1000倍,比起其它基于运算放大器的拓扑简单得多.该设计采用一个高CMRR差分放大器,只需两个电阻器就可设置差分增益(此例中的增益=2).     

The specific gravity of biodiesel and its blends with diesel fuel

The specific gravities of biodiesel and 75, 50, and 20% blends with No. 1 and No. 2 diesel fuels were measured as a function of temperature from the onset of crystallization to 100°C. The results indicate that biodiesel and its blends demonstrate temperature-dependent behavior that is qualitively similar to the diesel fuels. The temperature dependence of the specific gravity for biodiesel and its blends was compared with the ASTM D 1250-80 procedure for the temperature correction of hydrocarbon fuels, and the procedure was found to provide accurate corrections. A blending equation was developed that allows the specific gravity of blends to be calculated from the specific gravities of the biodiesel and diesel fuels.     

Pulse resistance effects due to charging or discharging of high-power lithium-ion cells: A path dependence study

Battery life estimations and state-of-health projections for commercial applications such as hybrid electric vehicles are highly dependent on accurate resistance monitoring. This study examined discharge/charge hysteresis (path dependency) effects on measuring resistance using two different lithium-ion cell chemistries. Cells were either discharged or charged to a target voltage, followed by a rest at open-circuit for electrochemical and thermal equilibration, immediately prior to a resistance measurement using a high-current pulse profile. Results show that a voltage hysteresis effect has an impact on cell resistance measurements, depending on the direction a target voltage is reached. Specifically, charging to a target condition yields different and less consistent resistance measurements compared to discharging to that same condition. Further, using slower rates to approach the target condition has a small impact on resistance on the discharge curve but does give a noticeable improvement on the charge curve. Unfortunately, slow charging and discharging are generally not practical for hybrid electric vehicle applications due to the rapidly changing power demands of the driver. Consequently, these results indicate that life estimates should be primarily based on resistances determined from pulses on the discharge curve.     

Heat management for hydrogen production by high temperature steam electrolysis

Many research and development projects throughout the world are devoted to sustainable hydrogen production processes. Low-temperature electrolysis, when consuming electricity produced without greenhouse gas emissions, is a sustainable process, though having limited efficiency.     

Retrospective on Aurora

This experience paper summarizes the key lessons we learned throughout the design and implementation of the Aurora stream-processing engine. For the past 2 years, we have built five stream-based applications using Aurora. We first describe in detail these applications and their implementation in Aurora. We then reflect on the design of Aurora based on this experience. Finally, we discuss our initial ideas on a follow-on project, called Borealis, whose goal is to eliminate the limitations of Aurora as well as to address new key challenges and applications in the stream-processing domain.Received: 21 October 2003, Accepted: 16 April 2004, Published online: 14 September 2004Edited by: J. Gehrke and J. Hellerstein.