Are Lévy flight patterns derived from the Weber–Fechner law in distance estimation?

Honeybees (Apis mellifera) are regularly faced with the task of navigating back to their hives from remote food sources. They have evolved several methods to do this, including compass-directed “vector” flights and the use of landmarks. If these hive-centered mechanisms are disrupted, bees revert to searching for the hive, using an optimal Lévy flight searching strategy. The same strategy is adopted when a food source at a known location ceases to be available. Here, we show that the programming for this Lévy strategy does not need to be very sophisticated or clever on the bee’s part, as Lévy flight patterns can be derived from the Weber–Fechner law in a bee’s odometer. Odometry errors of a different kind occur in desert ants (Cataglyphis spp., Melophorus bagoti). The searching behaviors of these ants are very similar in overall structure to that of honeybees but do not display any Lévy flight characteristics. We suggest that errors in the estimation of distance can be implicitly involved in shaping the structure of systematic search behavior and should not be regarded as merely deficiencies in the odometer.     

Royal jelly inhibited N-acetylation and metabolism of 2-aminofluorene in human liver tumor cells (J5)

The present study was carried out to evaluate the question of whether or not royal jelly affects N-acetylation and metabolism of 2-aminofluorene (2-AF) in the human liver tumor cell line (J 5). N-acetylation and metabolism of 2-AF in intact J5 cells was determined by using high performance liquid chromatography for the amounts of acetylated and nonacetylated 2-AF and profile of 2-AF metabolism. The results indicated that royal jelly displayed a dose-dependent inhibition of N-acetylation of 2-AF in J5 cells. Royal jelly also decreased the profile of 2-AF metabolites in J5 cells. This report is the first demonstration which showed that royal jelly affects N-acetylation of 2-AF in human liver tumor cells (J5).     

Molecular sieve material from liquid–crystal-display waste glass and silicon carbide sludge via hydrothermal process with alkali fusion pretreatment

Journal of Material Cycles and Waste Management - The goal of this paper was to synthesize eco-humidity-conditioned Al-MCM-41 mesoporous molecular sieves (CHCMs) from liquid–crystal-display...     

再生聚丙烯的洁净化和高质化应用

聚丙烯以其优异的机械性能、高的性价比和多重改性方式成为重要的通用树脂之一,这些产品废弃后产生了种类繁多和数量巨大的再生聚丙烯.通过将再生聚丙烯根据性能和来源进行分类,然后分类阐述各再生聚丙烯物料特点,结合再生聚丙烯改性方式,为高质化应用提出方向.     

我国环境监测仪器向规范化方向发展刍议

从我国环境监测事业发展和建立社会主义市场经济体制的需要，论述了加速我国环境监测仪器规范化的必要和可行性，并阐述了具体实施意见。     

我国地方煤矿的事故分析及预防对策

概述了我国煤矿事故的现状，对近几年我国地方煤矿的伤亡事故进行了统计分析，探讨了事故发生的原因，提出了预防对策     

社会主义市场经济条件下劳动安全卫生工作中的第三方认证与注册

我国正处在从计划经济向市场经济转轨的过程，劳动安全卫生管理系统也在发生着重要变化。根据劳动安全卫生管理工作中存在的问题，分析并提出利用非官方的、独立自主的第三方认证／注册机构的优点和缺点。     

Experimental study on non-destructive testing of rock bolts based on pseudo-random signal

The quality of rock bolt anchoring is closely related to the stability and safety of underground engineering and slope protection. In this paper, non-destructive testing of rock bolts is proposed based on pseudo-random signal, owing to the deficiencies of the conventional detecting method of stress wave reflection. The characteristics of pseudo-random signal for non-destructive testing of rock bolts are introduced. And the rock bolts are tested in the experiment, the time of reflection wave is identified and the length of rock bolts is calculated through cross correlation analysis between the extracted wavelet signal and the test signal. It is proved that the testing results of non-destructive testing methods based on pseudo-random signal are of low deviation. The experiment has shown that non-destructive testing of rock bolts based on pseudo-random signal is feasible with high precision.     

Exploring the perceived influence of safety management practices on project performance in the construction industry

Although safety management is known to be vital to construction projects, very few studies have solicited views from construction practitioners about their perceptions of which safety management practices (SMPs) are important to construction projects and related to project performance. An empirical study was undertaken in Hong Kong in order to shed more light on this topic. In the study, the importance levels of 15 popular SMPs and five project performance criteria were rated by 232 respondents. An exploratory factor analysis was conducted, and three SMP categories - information, process, and committees - were extracted. Of these three categories, safety management process was perceived by the construction practitioners as being the most important, followed by safety management information and committees. Moreover, the effect of the three SMP categories on a composite project performance variable was tested using hierarchical regression analysis. Results indicate that the “information” and “committees” categories were associated with project performance positively and significantly. One of the major conclusions of the study is that the construction industry has paid relatively less attention to safety management committees, which were empirically analyzed as having a strong perceived impact on project performance. In order to improve project performance, construction companies should promote the criticality of safety management committees.     

Quantitative indicator of homeostatic risk perception in car following

Driving behavior is largely affected by the risk perception of drivers. On the basis of risk homeostasis theory, we regard that drivers may adjust car movement according to the perceived risks fluctuating around a target level. However, the manner by which risk perception is quantified remains unclear. We propose assumptions on the quantitative indicators of risk perception and identify a suitable quantitative indicator of risk perception in car-following process. Three risk indicators are discussed, i.e. time-to-collision (TTC), time headway (TH), and safety margin (SM). Using homeostatic features as bases, we found that SM more suitably quantifies homeostatic risk perception than TTC or TH does. Data collected from video drive recorders installed in taxis operating in Beijing are used to analyze the target risk level of SM (desired SM, or DSM) of professional drivers during the car-following process. The data collected by Ahn et al. (2004) to verify Newell’s model are converted into DSM data to further analyze the target risk level of general drivers. The DSM histogram of professional drivers shows that the standard deviation of the DSM value is 0.115, with a mean value of 0.862 and a total distribution close to the normal distribution. For a general driver, the mean value of DSM is 0.896, which is higher than that of professional drivers. This research may shed lights on the understanding of driving behavior.