Modeling accident frequencies as zero-altered probability processes: An empirical inquiry

This paper presents an empirical inquiry into the applicability of zero-altered counting processes to roadway section accident frequencies. The intent of such a counting process is to distinguish sections of roadway that are truly safe (near zero-accident likelihood) from those that are unsafe but happen to have zero accidents observed during the period of observation (e.g. one year). Traditional applications of Poisson and negative binomial accident frequency models do not account for this distinction and thus can produce biased coefficient estimates because of the preponderance of zero-accident observations. Zero-altered probability processes such as the zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) distributions are examined and proposed for accident frequencies by roadway functional class and geographic location. The findings show that the ZIP structure models are promising and have great flexibility in uncovering processes affecting accident frequencies on roadway sections observed with zero accidents and those with observed accident occurrences. This flexibility allows highway engineers to better isolate design factors that contribute to accident occurrence and also provides additional insight into variables that determine the relative accident likelihoods of safe versus unsafe roadways. The generic nature of the models and the relatively good power of the Vuong specification test used in the non-nested hypotheses of model specifications offers roadway designers the potential to develop a global family of models for accident frequency prediction that can be embedded in a larger safety management system.     

Estimation of the reliability of measurement control of a technical system as regards system performance

A quantitative measure of the performance of a technical system is proposed. Mathematical models that establish the dependence of system performance on the probabilities of incorrect decisions in control of a technical system are obtained.     

Social ties and foreign market entry: An empirical inquiry

Abstract and Key Results

Reading as a method of inquiry: Representations of the born global

There exists a tension between the texture and complexity of what we investigate in IB and how we often convey to others our interpretations through research representations. Constructing rich, meaning-laden representations of IB research demands greater attention to not only how we write, but also how we read. For illustration, three different ‘readings’ of a Born Global narrative are offered.     

Assessing uncertainty and risk in exploited marine populations

The assessment and management of exploited fish and invertebrate populations is subject to several types of uncertainty. This uncertainty translates into risk to the population in the development and implementation of fishery management advice. Here, we define risk as the probability that exploitation rates will exceed a threshold level where long term sustainability of the stock is threatened. We distinguish among several sources of error or uncertainty due to (a) stochasticity in demographic rates and processes, particularly in survival rates during the early fife stages; (b) measurement error resulting from sampling variation in the determination of population parameters or in model estimation; and (c) the lack of complete information on population and ecosystem dynamics. The first represents a form of aleatory uncertainty while the latter two factors represent forms of epistemic uncertainty. To illustrate these points, we evaluate the recent status of the Georges Bank cod stock in a risk assessment framework. Short term stochastic projections are made accounting for uncertainty in population size and for random variability in the number of young surviving to enter the fishery. We show that recent declines in this cod stock can be attributed to exploitation rates that have substantially exceeded sustainable levels.     

我国水泥工业采标初探

随着改革开放的深入和社会主义市场经济的建立,标准化工作也要与国际接轨,采用国际标准和国外先进标准（以下简称采标）已逐渐成为国家与地方、行业与企业关注的焦点。而采标的目的是为提高我国产品质量和技术水平,适应发展社会主义市场经济和国际贸易的需要。作为泱泱...     

An assessment of the safety effects of the French speed camera program

This article presents the results of an evaluation of the speed camera program implemented in France in November 2003. The effects of this program on traffic casualties were estimated using interrupted time-series analyses. Various parametizations were attempted in order to capture changes in the constant and the slope of our traffic injury series. Results of the study reveal significant decreases in both fatal and non-fatal traffic injuries on the whole road network following deployment of the speed camera program. The fatality rate per 100,000 vehicles fell by 21% whereas the decrease in non-fatal traffic injuries displayed a decay function: a 26.2% reduction was recorded in the first month but dropped to 0.8% for the last observation of the series.     

Radioactivity contents in dicalcium phosphate and the potential radiological risk to human populations

Potentially harmful phosphate-based products derived from the wet acid digestion of phosphate rock represent one of the most serious problems facing the phosphate industry. This is particularly true for dicalcium phosphate (DCP), a food additive produced from either sulphuric acid or hydrochloric acid digestion of raw rock material. This study determined the natural occurring radionuclide concentrations of 12 DCP samples and 4 tricalcium phosphate (TCP) samples used for animal and human consumption, respectively. Metal concentrations (Al, Fe, Zn, Cd, Cr, As, Hg, Pb and Mg) were also determined. Samples were grouped into three different clusters (A, B, C) based on their radionuclide content. Whereas group A is characterized by high activities of ²³⁸U, ²³⁴U (10³ Bq kg⁻¹), ²¹⁰Pb (2 × 10³ Bq kg⁻¹) and ²¹⁰Po (800 Bq kg⁻¹); group B presents high activities of ²³⁸U, ²³⁴U and ²³⁰Th (10³ Bq kg⁻¹). Group C was characterized by very low activities of all radionuclides (<50 Bq kg⁻¹). Differences between the two groups of DCP samples for animal consumption (groups A and B) were related to the wet acid digestion method used, with group A samples produced from hydrochloric acid digestion, and group B samples produced using sulphuric acid. Group C includes more purified samples required for human consumption. High radionuclide concentrations in some DCP samples (reaching 2 × 10³ and 10³ Bq kg⁻¹ of ²¹⁰Pb and ²¹⁰Po, respectively) may be of concern due to direct or indirect radiological exposure via ingestion. Our experimental results based on ²¹⁰Pb and ²¹⁰Po within poultry consumed by humans, suggest that the maximum radiological doses are 11 ± 2 μSv y⁻¹. While these results suggest that human health risks are small, additional testing should be conducted.     

有机插层微晶白云母作环境矿物材料的探索综述

中国首次发现的沉积微晶白云母岩,其矿石组分比较简单,白云母呈板状微晶产出,矿石储量大,易采、易选、易加工,成本低廉,用途广阔.本文介绍有机插层微晶白云母作环境矿物材料的可行性、方法,及环境治理用途以及其巨大的潜在开发利用前景.     

Regeneration of the limb: opinions on the reality

Whenever the topic of re-growing human limbs is posed for discussion, it is often argued that ‘if a newt can do it, then so can we’. This notion, albeit promising, is somewhat like watching a science-fiction film; the individual components are currently available but we are far from realizing the complete picture. Today’s reality is that if we are faced with a limb-severing injury, any regenerative attempt would endeavour to accelerate the pace at which the tissue heals to a clinically relevant/functional state. The science of limb regeneration can be approached from three different angles, developmental biology; regenerative medicine; and tissue engineering. This opinion piece describes how each approach can be used to understand the concepts behind regeneration, how far each approach has advanced and the hurdles faced by each of the approaches.     

An ecology of ideology: theory and evidence from four populations

This paper analyzes the founding rates of two types of Jewishagricultural cooperatives, the moshav and the kibbutz, to showhow political ideology intersects with resource requirementsto produce competition and mutualism between organizations.These two populations, which share ideology and a resource base,competed with each other. They both enjoyed mutualism with thepopulation of credit cooperatives, which represented a kindredideology, but relied on different resources. They both sufferedcompetition from the population of corporations, which representeda rival ideology, capitalism.     

Different risk thresholds in pedestrian road crossing behaviour: A comparison of French and Japanese approaches

When crossing the road, pedestrians have to make a trade-off between saving time and avoiding any risk of injuries. Here, we studied how culture influences an individual's perception of risks when crossing a street, using survival analysis. This study is the first to use this analysis to assess cognitive mechanisms and optimality of decisions underlying road crossing behaviour. We observed pedestrian behaviour in two city centres: Inuyama (Japan) and Strasbourg (France). In each city, observations were made at a safe site consisting of a crosswalk and a street light and at an unsafe site (i.e. no crosswalk or street light). At the unsafe site, we measured the time needed by a pedestrian to take a decision (T_dec). During T_dec, a pedestrian estimates whether he can (T_safe) or cannot (T_risk) cross the road. Using survival analysis, we studied the distributions of these three time variables and showed that French pedestrians took more risks than Japanese pedestrians, and that males took more risks than females, but only in Japan. More studies would considerably broaden our understanding on how culture may affect decision-making processes under risky circumstances.     

An experiment on the evaluation of information under risk and ambiguity

Assume a decision maker has a choice between several acts. Some of the alternatives are simple lotteries; others consist of gathering additional (costy) information on outcomes or probabilities of the available simple lotteries prior to making a binding choice between them. In this paper hypotheses are derived from the Choquet Expected Utility model about the relationship between the degree of ambiguity aversion and the willingness-to-pay for information revealing the outcome of simple two-state-lotteries. These hypotheses are tested experimentally. 157 students are asked to state their willingness-to-pay for information, revealing the true payment relevant state, before making choices between a certain amount of money and two-state-lotteries of varying degrees of ambiguity. In the experiment the pessimism predicted by the Choquet Expected Utility model is not observed empirically.Funding for the work was provided by the Deutsche Forschungsgemeinschaft, grant No. We 993/5-3     

Performance Measurement in the Belgian Document Ordering and Delivery System Impala

This paper deals with performance measures and performance indicators in the Impala electronic document ordering and delivery system for research libraries in Belgium and compares these with some international standards as, e.g., the ProLib/PI study commissioned by the European Commission.Performance measures: Costs (clearinghouse principle) Number of ILL requests made to other libraries Number of ILL requests made to other libraries without success Number of ILL requests made to other libraries with success Number of ILL requests received from other libraries Number of ILL requests received from other libraries and not satisfied Number of ILL requests received from other libraries that were satisfied Frequency asked titlesPerformance indicators: Success rate Borrowing-lending ratio per library Response times, split into several segments of the ILL-procedureThe article concludes with some indications for quality measurement in electronic document delivery where Impala will be able to measure the real supply times as perceived by the end user.     

对氧气设施安全的一些意见

文章就氧气设施安全的重要性作了论述 ,对历年来氧气设施的事故 (设备、管道、气瓶 )进行了回顾 ,对如何加强氧气设施的安全提出了 5点意见     

Control of the risk of exposure to alpha emitting radionuclides in French nuclear power plants: example of Cattenom

Control of the risk of internal exposure of EDF PWR plant maintenance workers by alpha-emitting radioactive elements is based on identification and quantification of the contamination of the systems. In 2001, an experiment carried out at Cattenom Power Plant during a unit outage in the presence of a leaking fuel cladding, based on measurement of alpha-emitting radioactive elements, made it possible to determine a realistic particle resuspension coefficient. A resuspension coefficient of 10(-6) m(-1) was adopted for operational radiological protection. An appropriate monitoring system for workers was set in place in collaboration with the occupational medicine and radiological protection department. It was based on prior estimation of the level of alpha contamination, and confirmed by swipe measurements, atmospheric surveillance by monitors, and collective analysis by nose blow samples from workers selected on the basis of their workstations, as well as supplementary individual measurements (monitoring of faeces). This surveillance made it possible to validate an appropriate work area monitoring system.     

Intelligent machines in the twenty-first century: foundations of inference and inquiry

The last century saw the application of Boolean algebra to the construction of computing machines, which work by applying logical transformations to information contained in their memory. The development of information theory and the generalization of Boolean algebra to Bayesian inference have enabled these computing machines, in the last quarter of the twentieth century, to be endowed with the ability to learn by making inferences from data. This revolution is just beginning as new computational techniques continue to make difficult problems more accessible. Recent advances in our understanding of the foundations of probability theory have revealed implications for areas other than logic. Of relevance to intelligent machines, we recently identified the algebra of questions as the free distributive algebra, which will now allow us to work with questions in a way analogous to that which Boolean algebra enables us to work with logical statements. In this paper, we examine the foundations of inference and inquiry. We begin with a history of inferential reasoning, highlighting key concepts that have led to the automation of inference in modern machine-learning systems. We then discuss the foundations of inference in more detail using a modern viewpoint that relies on the mathematics of partially ordered sets and the scaffolding of lattice theory. This new viewpoint allows us to develop the logic of inquiry and introduce a measure describing the relevance of a proposed question to an unresolved issue. Last, we will demonstrate the automation of inference, and discuss how this new logic of inquiry will enable intelligent machines to ask questions. Automation of both inference and inquiry promises to allow robots to perform science in the far reaches of our solar system and in other star systems by enabling them not only to make inferences from data, but also to decide which question to ask, which experiment to perform, or which measurement to take given what they have learned and what they are designed to understand.     

Comparison between thermoluminescence and electronic dosimetry results at the Belgian Nuclear Research Centre

At the Belgian Nuclear Research Centre, SCK.CEN, the official dose of record is measured by thermoluminescence dosemeters (TLDs), read out on a monthly basis. The workers who frequently enter controlled areas also wear an electronic dosemeter (ED), in addition, as an ALARA tool. In this paper the dose values registered by both dosimetry systems during 1 year are compared. Special attention was given to the determination of the background radiation. The general agreement was good, although the TLD gave slightly higher values. An exercise like this yielded useful information on the storage and use of dosemeters by personnel and on the lowest limit of detection obtained with both systems.