Methylmercury levels in predatory fish species marketed in Canada

Mercury was detected in all analysed samples of swordfish, marlin, shark and tuna purchased from major supermarket outlets and fish retailers in three cities across Canada. Total mercury and methylmercury levels ranged up to 3845 and 2346 ng g^-1, respectively. Swordfish contained the highest levels, followed by shark, fresh/frozen tuna and marlin. Levels in canned tuna were considerably less than the other examined samples. Methylmercury was extracted with toluene from enzymatically hydrolysed samples after the addition of sulphuric acid and potassium bromide. An L-cysteine back-extraction was used to separate the methylmercury from most organic co-extractives. Analysis of methylmercury (as methylmercury bromide) was by gas chromatography with pulsed discharge detection.     

A cognitive and social psychological analysis of disclosure laws and call for mortgage counseling to prevent predatory lending.

The federal government’s primary method of protecting consumers from “predatory lending” has been to enact disclosure laws that were supposed to enable consumers to make informed decisions. This article contends that notwithstanding these disclosure laws, unscrupulous mortgage brokers and lenders have been able to take advantage of certain described cognitive and social psychological phenomena to induce borrowers to enter into predatory loans, and argues that disclosures alone—even the recently revised disclosure forms—are inadequate. To better empower consumers to make informed decisions on their home loans, this article proposes and details a mortgage counseling intervention that contains both “in-person” and interactive computer counseling as a necessary supplement to disclosure laws. Designed properly, such an intervention would more effectively address the cognitive and social psychological barriers to rational decision making than disclosure alone. The article also examines the likely costs and benefits of the proposed mortgage counseling intervention in light of Illinois experience with mortgage counseling and urges policymakers to consider not only the costs of implementing mortgage counseling but also the costs of not providing for this counseling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of chemically mediated prey-search response in postlarval lobsters (Homarus americanus) through feeding experience

Postlarval lobsters were fed live amphipods (Gammarus oceanicus), soft clam spat (Mya arenaria), or frozen brine shrimp (Artemia salina) for five weeks in order to determine by behavioral bioassay if chemically mediated prey-search behavior is established by feeding experience. Chemosensory responses of predatorily naive lobsters to live clam and amphipod metabolites were low and erratic. After five weeks, amphipod-fed lobsters had developed strong responses towards amphipod metabolites but not clam metabolites. In contrast, clam-fed lobsters did not develop responses to either prey. Chemical fractionation of amphipod metabolites indicated that attractants were confined to the same fraction as for prey extracts, i.e., polar, low-molecular-weight compounds. Survival (80–90%) was similar for each diet group; growth was greatest for amphipod-fed lobsters (100%), followed by clam-fed lobsters (72%) and brine shrimp-fed lobsters (18%); and feeding rates increased for amphipod-fed lobsters and decreased for clam-fed lobsters. Coloration of lobsters indicated that only amphipod diet provided desirable pigments. Differences in ingestive conditioning results between clamfed and amphipod-fed lobsters may have been related to (1) clam metabolites being qualitatively or quantitatively less attractive than amphipod metabolites or (2) differences in the predisposition of lobsters to show ingestive conditioning to different prey and their associated metabolites as a function of quality of prey as a diet.     

Herbivory induces systemic production of plant volatiles that attract predators of the herbivore: Extraction of endogenous elicitor

It was previously shown that in response to infestation by spider mites (Tetranychus urticae), lima bean plants produce a volatile herbivoreinduced synomone that attracts phytoseiid mites (Phytoseiulus persimilis) that are predators of the spider mites. The production of predator-attracting infochemicals was established to occur systemically throughout the spider mitein-fested plant. Here we describe the extraction of a water-soluble endogenous elicitor from spider mite-infested lima bean leaves. This elicitor was shown to be transported out of infested leaves and was collected in water in which the petiole of the infested leaf was placed. When the petioles of uninfested lima bean leaves were placed in water in which infested leaves had been present for the previous seven days, these uninfested lima bean leaves became highly attractive to predatory mites in an olfactometer when an appropriate control of uninfested lima bean leaves was offered as alternative. The strength of this effect was dependent on the number of spider mites infesting the elicitor-producing leaves. Higher numbers of spider mites resulted in an elicitor solution with a stronger effect. In addition, spider mite density was important. The elicitor obtained from one leaf with 50 spider mites had a stronger effect on the attractiveness of uninfested leaves than the elicitor obtained from three leaves with 17 spider mites each. This suggests that the stress intensity imposed on a plant is an important determinant of the elicitor quantity. While the elicitor has a strong effect on the attractiveness of uninfested leaves, spider mite-infested leaves are still much more attractive to predatory mites than elicitor-exposed leaves. The data are discussed in the context of systemic effects in plant defense and the biosynthesis of herbivore-induced terpenoids in plants.     

应用捕食搜索策略的改进多态蚁群算法

结合捕食搜索策略对多态蚁群算法进行改良。该算法引入以下机制：在人工蚁选择路径阶段，设置侦查素路径为优先，为非侦查素路径设置惩罚因子；利用权值在侦查素和非侦查素路径都施加信息素，通过该机制避免多态蚁群算法陷入停滞；在每轮人工蚁最优结果的邻域应用捕食搜索策略，并通过竞争机制选择最优解更新信息素。通过TSP的仿真实验结果表明，提出的融合算法可以有目的地指导信息素分布，加快算法向最优解的收敛速度及提高最优解质量，克服传统多态蚁群算法的缺陷。     

粉末涂装中逸粉的危害及解决措施

列举了粉末喷涂过程设备逸粉的危害，提出粉末喷涂设备设计要“五位一体”统筹考虑的设计思想，并从设备选型、设备设计、设备管理、设备改造诸方面提出防止粉末外逸的解决方案。     

Volatile Allelochemicals in the <Emphasis Type="Italic">Ageratum conyzoides</Emphasis> Intercropped Citrus Orchard and their Effects on Mites <Emphasis Type="Italic">Amblyseius newsami</Emphasis> and <Emphasis Type="Italic">Panonychus citri</Emphasis>

Ageratum conyzoides L. weed often invades cultivated fields and reduces crop productivity in Southeast Asia and South China. However, intercropping this weed in citrus orchards may increase the population of predatory mite Amblyseius newsami, an effective natural enemy of citrus red mite Panonychus citri, and keep the population of P. citri at low and noninjurious levels. This study showed that A. conyzoides produced and released volatile allelochemicals into the air in the intercropped citrus orchard, and these volatiles influenced the olfactory responses of A. newsami and P. citri. At test temperature (25°C), A. conyzoides fresh leaves, its essential oil, and major constituents, demethoxy-ageratochromene, β-caryophyllene, α-bisabolene, and E-β-farnesene, attracted A. newsami and slightly repelled P. citri. Field experiments demonstrated that spraying A. conyzoides essential oil emulsion in an A. conyzoides nonintercropped citrus orchard increased the population density of A. newsami from below 0.1 to over 0.3 individuals per leaf, reaching the same level as in an A. conyzoides intercropped citrus orchard. However, this effect could not be maintained beyond 48 hr because of the volatility of the essential oil. In contrast, in the A. conyzoides intercropped citrus orchard, A. conyzoides plants continuously produced and released volatile allelochemicals and maintained the A. newsami population for a long time. The results suggest that intercropping of A. conyzoides not only made the citrus orchard ecosystem more favorable for the predatory mite A. newsami, but also that the volatile allelochemicals released from A. conyzoides regulated the population of A. newsami and P. citri.     

Fear, risk assessment, and playfulness in the juvenile rat.

The effects of predatory odors on play were assessed in juvenile rats. When rats were exposed directly to a collar previously worn by a cat, play was abolished and remained suppressed for up to 6 days. Providing rats with an opportunity to hide did not alter cat odor's ability to reduce their play. Rat play was also suppressed shortly after they were exposed to cat odor in their home cage, and a substantial amount of risk assessment behavior was present up to 24 hr later. Trimethylthiazoline, a component found in fox feces, only reduced play during exposure. These data suggest that predatory odor-induced reductions in play may provide a useful model for gaining insight into the consequences of fear and anxiety in young animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

加油站逃单事件的分析及预防

对某公司加油站发生的21起逃单事件，从逃单时间、选单车辆及逃单当事人的一些特征进行了分析，介绍了一些预防加油站逃单事件发生的对策，以及出现逃单事件后的注意事项。     

防洪避难系统在东平湖滞洪区的运用

本研究选用动态规划中的最优控制方法，为滞洪区内的居民避难设计了相对最优的避难路径，选用的目标函数避难路径最短，相对而言，实施避难时最为省时，基于分洪区内居民居分散，首路锚综复杂及行政区划分等特定约束，本模型中对不同道路采用分级考虑，且分别计入不同气候，不同分区各自避难等诸多因素，进行了多工况的实施方案比较，研究成果不仅为滞洪区内各村民提供了具体的相对最优的避难路径，且根据各方宁比较中得知的优劣，对