Cross-Contamination During Food Preparation: A Mechanistic Model Applied to Chicken-Borne Campylobacter

We develop a model for bacterial cross-contamination during food preparation in the domestic kitchen and apply this to the case of Campylobacter-contaminated chicken breast. Building blocks of the model are the routines performed during food preparation, with their associated probabilities of bacterial transfer between food items and kitchen utensils. The model is used in a quantitative microbiological risk assessment (QMRA) of Campylobacter in the Netherlands. Using parameter values from the literature and performing elementary sensitivity analyses, we show that cross-contamination can contribute significantly to the risk of Campylobacter infection and find that cleaning frequency of kitchen utensils and thoroughness of rinsing of raw food items after preparation has more impact on cross-contamination than previously emphasized. Furthermore, we argue that especially more behavioral data on hygiene during food preparation is needed for a comprehensive Campylobacter risk assessment.     

Food Safety in the Domestic Environment: An Interdisciplinary Investigation of Microbial Hazards During Food Preparation

It has been established that, to a considerable extent, the domestic hygiene practices adopted by consumers can result in a greater or lesser microbial load in prepared meals. In the research presented here, an interdisciplinary study is reported in which interviews, observations of consumers preparing a recipe, and microbial contamination of the finished meals were compared. The results suggest that, while most consumers are knowledgeable about the importance of cross-contamination and heating in preventing the occurrence of foodborne illness, this knowledge is not necessarily translated into behavior. The adoption of habitual cooking practices may also be important. Potentially risky behaviors were, indeed, observed in the domestic food preparation environment. Eighteen of the participants made errors in food preparation that could potentially result in cross-contamination, and seven participants allowed raw meat juices to come in contact with the final meal. Using a tracer microorganism the log reduction as a result of consumer preparation was estimated at an average of log 4.1 cfu/salad. When combining these findings, it was found that cross-contamination errors were a good predictor for log reduction. Procedural food safety knowledge (i.e., knowledge proffered after general open questions) was a better predictor of efficacious bacterial reduction than declarative food safety knowledge (i.e., knowledge proffered after formal questioning). This suggests that motivation to prepare safe food was a better indicator of actual behavior than knowledge about food safety per se.     

Scheduling to Improve Field Service Quality*

This research addresses the problem of scheduling technicians to travel from customer site to customer site to perform emergency maintenance on office machines, computers, robots, telecommunications equipment, medical equipment, heating/cooling equipment, household appliances, and other equipment. We call this the Traveling Technician Problem (TTP). In its simplest form, the TTP is a multiserver, sequence-dependent, tardiness minimization problem. This research frames the TTP as a service quality maximization problem in which service quality is defined in terms of mean tardiness, mean technician phone response time, mean promise time, and mean response time. Tardiness is defined with respect to contractually guaranteed response times. Industry practice is to use dispatching rules to assign service calls to technicians. This research proposes scheduling procedures to maximize field service quality in a dynamic environment. A simulation experiment was used to compare three dispatching rules and three scheduling procedures for the TTP. The scheduling procedures dominated the dispatching rules on all four service quality measures. The proposed scheduling procedures hold promise for improving service quality in a wide variety of field service organizations and in other scheduling environments as well.     

Assessing Interventions to Reduce the Risk of Campylobacter Prevalence in Broilers

As part of a comprehensive risk assessment on the Campylobacter prevalence in the chicken production chain (from young born chicken till chicken fillet) in the Netherlands, we formulated a quantitative model on the transmission dynamics of Campylobacter at Dutch broiler farms. This model is used to quantify the risk of Campylobacter prevalence in broilers at the time that flocks leave the farm for processing. To this end, we assumed that the Campylobacter prevalence is primarily determined by two parameters, that is, the within- and between-flock transmission. The within-flock transmission was assessed fitting experimental data to a logistic growth model and the between-flock transmission was assessed fitting field data to a generalized linear model (GLM), which included three possible infection routes: (1) via an infected flock in the previous cycle, (2) via other infected flocks present on the farm, and (3) from other sources. This model was applied to assess the efficacy of three control scenarios; (1) a ban on other livestock on broiler farms, (2) a ban on thinning, and (3) a reduction of the between-flock transmission. In contrast to the other scenarios, the third one was shown to be most effective. Theoretically, this is accomplished by improved biosecurity. However, the impact of improved biosecurity cannot be specified into specific control measures, and therefore it is not clear what investments are needed. Finally, we also assessed the efficacy of scheduled treatment, that is, fresh meat production solely from test-negative flocks. We found that the reliability of negative test results, which is crucial, strongly depends on the length of time between testing and slaughter. The sensitivity and specificity of the test appeared to be of minor importance.     

大力改进领导方式和领导方法

江泽民同志在安徽视察时强调,进一步改进领导方式和领导方法,实现领导方式和领导方法的创新,是当前加强党的建设,也是做好各项工作面临的一个重大课题.在纪念建党80周年重要讲话中,江泽民同志又重申了这一要求.这一重要思想具有强烈的针对性和重要的现实意义.     

A Review of Training Strategies to Teach Individuals Implementation of Behavioral Interventions

The purpose of this review is to provide a critical analysis of research on staff training procedures to identify best practices as well as unanswered questions, which may be addressed in future research. We analyzed 24 articles along the dimensions of participant and intervention characteristics; the procedures targeted for training, training components, and mediums of delivery; the duration of training and the effectiveness of the outcomes; the generality; and the social validity of the training strategies. We discussed the implication of the findings as they relate to research and practice.     

Setting Priorities in Behavioral Interventions: An Application to Reducing Phishing Risk

Phishing risk is a growing area of concern for corporations, governments, and individuals. Given the evidence that users vary widely in their vulnerability to phishing attacks, we demonstrate an approach for assessing the benefits and costs of interventions that target the most vulnerable users. Our approach uses Monte Carlo simulation to (1) identify which users were most vulnerable, in signal detection theory terms; (2) assess the proportion of system‐level risk attributable to the most vulnerable users; (3) estimate the monetary benefit and cost of behavioral interventions targeting different vulnerability levels; and (4) evaluate the sensitivity of these results to whether the attacks involve random or spear phishing. Using parameter estimates from previous research, we find that the most vulnerable users were less cautious and less able to distinguish between phishing and legitimate emails (positive response bias and low sensitivity, in signal detection theory terms). They also accounted for a large share of phishing risk for both random and spear phishing attacks. Under these conditions, our analysis estimates much greater net benefit for behavioral interventions that target these vulnerable users. Within the range of the model's assumptions, there was generally net benefit even for the least vulnerable users. However, the differences in the return on investment for interventions with users with different degrees of vulnerability indicate the importance of measuring that performance, and letting it guide interventions. This study suggests that interventions to reduce response bias, rather than to increase sensitivity, have greater net benefit.     

领导者韧性领导力的增进思路

韧性领导力是一个组织走出危机、持续成长的核心战略资源,其增进之道在于从领导者的心智思维角度切入,形成批判式思维,培育平衡式思维,激发集体智慧和强化学习能力。     

Bayesian Networks to Compare Pest Control Interventions on Commodities Along Agricultural Production Chains

The production of an agricultural commodity involves a sequence of processes: planting/growing, harvesting, sorting/grading, postharvest treatment, packing, and exporting. A Bayesian network has been developed to represent the level of potential infestation of an agricultural commodity by a specified pest along an agricultural production chain. It reflects the dependency of this infestation on the predicted level of pest challenge, the anticipated susceptibility of the commodity to the pest, the level of impact from pest control measures as designed, and any variation from that due to uncertainty in measure efficacy. The objective of this Bayesian network is to facilitate agreement between national governments of the exporters and importers on a set of phytosanitary measures to meet specific phytosanitary measure requirements to achieve target levels of protection against regulated pests. The model can be used to compare the performance of different combinations of measures under different scenarios of pest challenge, making use of available measure performance data. A case study is presented using a model developed for a fruit fly pest on dragon fruit in Vietnam; the model parameters and results are illustrative and do not imply a particular level of fruit fly infestation of these exports; rather, they provide the most likely, alternative, or worst‐case scenarios of the impact of measures. As a means to facilitate agreement for trade, the model provides a framework to support communication between exporters and importers about any differences in perceptions of the risk reduction achieved by pest control measures deployed during the commodity production chain.     

Psychological Determinants of Reactions to Food Risk Messages

In recent years, European countries have witnessed a number of food crises such as dioxin-contaminated chicken, foot-and-mouth disease, and BSE. In such cases, food might be contaminated by microorganisms or chemicals that could pose a risk to the consumer. These cases attract media attention and might instigate the consumer to reduce the consumption of the allegedly contaminated products. Although a decline in consumption of (potentially) contaminated products has been observed, it is not yet clear what determines the individual's reaction to food risk messages. To study the psychological determinants of the reaction to food risk messages, a survey was conducted in the Netherlands (n= 280). Subjects had to imagine two situations involving chicken contamination and report how they would react behaviorally if this situation occurred. Risk perception, affective response, perceived susceptibility to foodborne disease, self-efficacy, outcome expectation, trust, experience with foodborne disease, and need for information were also assessed. It was found that 60% of the subjects would allegedly avoid the risks by not consuming chicken for a while and approximately 60% would seek additional information. Risk avoidance was significantly related to information seeking and the psychological determinants, especially risk perception, affective response, need for information, perceived susceptibility to foodborne disease, and trust. Seeking information was also significantly related to risk perception, affective response, need for information, susceptibility to foodborne disease, and trust, but to a lesser degree. A model describing the relationships between the variables was tested using AMOS. Results are presented and implications are discussed.     

提升单位治理效能的关键因素与创新路径

治理客观环境复杂化、治理内在需求多样化和治理主体多元化是促使单位提升治理效能的客观要求。从单位角度看,员工参与度、公平感、幸福感和满意度是影响单位治理效能提升的关键因素。单位领导者可以从打造多元共治治理格局、建构公平共建共享制度、优化单位人文关怀机制和完善单位公共服务体系等方面出发创新单位治理机制,提升单位治理效能。     

Faculty Performance Evaluation: Modeling to Improve Personnel Decisions*

Based on likely future changes in faculty evaluation practices, this paper examines how institutions of higher education might operationalize performance evaluation as related to research, teaching, and service. A model is developed that allows coupling performance evaluation and relevant market considerations with merit pay, tenure, and promotion decisions. The approach is specifically applicable to tenure-track faculty members in colleges and universities.     

The Use of Telematics Devices to Improve Automobile Insurance Rates

Most automobile insurance databases contain a large number of policyholders with zero claims. This high frequency of zeros may reflect the fact that some insureds make little use of their vehicle, or that they do not wish to make a claim for small accidents in order to avoid an increase in their premium, but it might also be because of good driving. We analyze information on exposure to risk and driving habits using telematics data from a pay‐as‐you‐drive sample of insureds. We include distance traveled per year as part of an offset in a zero‐inflated Poisson model to predict the excess of zeros. We show the existence of a learning effect for large values of distance traveled, so that longer driving should result in higher premiums, but there should be a discount for drivers who accumulate longer distances over time due to the increased proportion of zero claims. We confirm that speed limit violations and driving in urban areas increase the expected number of accident claims. We discuss how telematics information can be used to design better insurance and to improve traffic safety.     

加强组工干部能力建设的思考

加强组工干部的能力建设,既是一个新话题,又是一个老课题。在开展保持共产党员先进性教育活动中,如何通过进一步加强能力建设,切实发挥组工干部的表率作用,是我们必须认真审视和思考的问题。刻苦学习,充实自己要确立终身刻苦学习的好态度。一要注重学习。要把学习作为进步的基础和阶梯,不受社会上学风不浓、玩风太盛现象的影响,让电子计算机的键盘声代替麻将桌上的洗牌声,让朗朗的读书声代替酒桌上的划拳声。要通过刻苦学习,增强自己的真才实学。否则,一个没有真才实学的人,即使通过种种不正当的手段升到了高位,也终有一天会被别人一脚踹下…     

A Procedure to Improve Compliance with Coal Mine Safety Regulations

Safety performance in underground coal mines consists of a wide array of preventive behaviors designed to lessen the possibility of accidental injury or a major mine disaster. Recognizing that some of the greatest catastrophes in the past have been due to fires and explosions, underground coal mines are now required to establish and maintain working ventilation systems, with numerous support behaviors required on each working section. Compliance is monitored through periodic inspections by Mine Safety and Health Administration (MSHA) inspectors, who have the authority to cite and impose a monetary fine on the company when any of these preventive measures are in non-compliance. The current study was targeted toward a reduction in ventilation violations issued by MSHA inspectors at a mine with four coal-producing sections. Performance data were monitored through weekly inspections of each section by a company health and safety inspector assigned to the mine. Through a combined program of periodic observation, contingent punitive control, praise, and graphic feedback, the mine operated for 10 consecutive months without a ventilation violation.     

A Comparison of Unconstraining Methods to Improve Revenue Management Systems

Asuccessful revenue management system requires accurate demand forecasts for each customer segment. The forecasts are used to set booking limits for lower value customers to ensure an adequate supply for higher value customers. The very use of booking limits, however, constrains the historical demand data needed for an accurate forecast. Ignoring this interaction leads to substantial penalties in a firm's potential revenues. We review existing unconstraining methods and propose a new method that includes some attractive properties not found in the existing methods. We evaluate several of the common unconstraining methods against our proposed method by testing them on intentionally constrained simulated data. Results indicate our proposed method outperforms other methods in two of three data sets. We also test the revenue impact of our proposed method, expectation maximization (EM), and “no unconstraining” on actual booking data from a hotel/casino. We show that performance varies with the initial starting protection limits and a lack of unconstraining leads to significant revenue losses.     

如何有效利用我国失业保险基金以促进再就业

我国失业保险基金大量闲置,促进就业功能难以发挥,国内对失业保险优化相关领域的研究又基本空缺.本文针对这一问题总结了西方基于促进就业的优化失业保险的四种途径,并在此基础上根据我国目前的状况,提出了合理运用我国失业保险基金、优化我国失业保险的一系列政策建议.     

Multi‐Exposure Pathway Model to Compare Escherichia coli O157 Risks and Interventions

The relative contributions of exposure pathways associated with cattle‐manure‐borne Escherichia coli O157:H7 on public health have yet to be fully characterized. A stochastic, quantitative microbial risk assessment (QMRA) model was developed to describe a hypothetical cattle farm in order to compare the relative importance of five routes of exposure, including aquatic recreation downstream of the farm, consumption of contaminated ground beef processed with limited interventions, consumption of leafy greens, direct animal contact, and the recreational use of a cattle pasture. To accommodate diverse environmental and hydrological pathways, existing QMRAs were integrated with novel and simplistic climate and field‐level submodels. The model indicated that direct animal contact presents the greatest risk of illness per exposure event during the high pathogen shedding period. However, when accounting for the frequency of exposure, using a high‐risk exposure‐receptor profile, consumption of ground beef was associated with the greatest risk of illness. Additionally, the model was used to evaluate the efficacy of hypothetical interventions affecting one or more exposure routes; concurrent evaluation of multiple routes allowed for the assessment of the combined effect of preharvest interventions across exposure pathways—which may have been previously underestimated—as well as the assessment of the effect of additional downstream interventions. This analysis represents a step towards a full evaluation of the risks associated with multiple exposure pathways; future incorporation of variability associated with environmental parameters and human behaviors would allow for a comprehensive assessment of the relative contribution of exposure pathways at the population level.     

领导者提高变革性决策安全系数的技术途径

技术嵌入具有推动单位决策实现从经验决策走向数据决策、从封闭决策走向开放决策、从被动决策走向主动决策、从粗放决策走向精细化决策等多重优势,领导者可借助信息技术来夯实决策根基、优化决策机制、加强决策监控、提高决策能力,从而提高变革性决策安全系数。     

The Potential of Next-Generation Microbiological Diagnostics to Improve Bioterrorism Detection Speed

Emerging, rapid, multivalent, microbial diagnostic technologies can produce results in hours, as contrasted to the standard methods that require at least the better part of a week. Used in bioterrorism surveillance in medical settings, the new biodetectors could significantly reduce the time between a covert attack and its detection. By how much is determined by the intensity of sampling. If used to screen all patients reporting flu-like symptoms to their doctors, this basic level of "front-line" sampling would reduce life-threatening medical floundering and missteps and give responders 3-5 days of warning that they otherwise would not have had. Being miniaturized and amenable to mass production, these devices could reduce the cost of screening to a fraction of current costs and so it is tempting to imagine their use in more intensive bioterrorism screening programs aimed at the apparently healthy population, programs that could detect a covert attack even before the victims felt ill. This article examines the tradeoffs between surveillance effort and probability of detection for such programs. Dual-use deployment, where the biodetector provides some medically useful information in addition to bioterrorism surveillance, is discussed.