Scheduling Truck Arrivals at an Air Cargo Terminal

We consider the scheduling of truck arrivals at an air cargo terminal. By coordinating arrivals of cargo delivery trucks with outbound flight departure schedules, some of the shipments can be transferred directly to the departing flights, while others will be stored at the terminal's storage facility and incur extra handling and storage costs. The objective is to obtain a feasible schedule so as to minimize the total cost of operations. We formulate the problem as a time‐indexed integer program and show that, even with limited number of unloading docks at the terminal, the problem is non‐trivial (NP‐hard in the strong sense). Our solution method includes an exact solution procedure to determine an optimal unloading sequence for the shipments carried by each truck, together with a Lagrangian relaxation‐based heuristic for assigning trucks to truck docks and determining truck arrival times. We conducted computational experiments to test the performance of our solution method. Computational results show that our method can generate near‐optimal solutions efficiently. Our simulation results indicate that the scheduling approach proposed in this paper has the potential to generate significant cost savings over a first‐come, first‐served approach currently used at the air cargo terminal that we observed.     

The healing power of dogs: Cocoa's story

Animals bring a sense of "at homeness" and even normalcy to people who are hospitalized or live in health care facilities. Illnesses, separation from family, fear, loneliness, and even depression may be lessened for those who receive a therapy dog visit by providing a welcome change in routine and something to look forward to. Individuals are often more active and responsive during and after a visit. Just stroking and petting a dog requires the use of hands and arms, as well as the motions of stretching and turning. Dogs are also unconcerned with age or physical ability; they accept people as they are. This alone causes many to reach out and interact with dogs. Animals provide a focus for conversation and a common interest. As Cocoa's human partner can attest, a pet also makes it easier for strangers to talk. Cocoa is known by so many people at the facilities she visits that residents' family members often stop to talk with "Cocoa's mom" when they meet her in the community, asking questions about how Cocoa is doing. When Cocoa is no longer able to perform her services, many in her community will mourn. Cocoa's story, as well as the limited research literature, supports the positive physical and psychological effects of animals, but continued research on the effect of therapy animals on health outcomes is needed. As advocates for clients, nurses are in key positions to facilitate the inclusion of animals in clients' care. Although not for everyone, including those who react negatively to animals or who are allergic, pet therapy offers important possibilities for providing holistic care that extends not only to clients, but also to family members and staff, and to the pets themselves.     

Characteristics of Older Adult Problem Gamblers Calling a Gambling Helpline

Background Few investigations have characterized groups of older adults with gambling problems, and published reports are currently limited by small samples of older adult problem gamblers. Gambling helplines represent a widespread mechanism for assisting problem gamblers to move into treatment settings. Given data from older adult problem gamblers in treatment, we hypothesized that older as compared with younger adult problem gamblers calling a gambling helpline would be less likely to report gambling-related problems.Design and methods Logistic regression analyses were performed on data obtained from January 1, 2000 to December 31, 2001, inclusive, from callers with gambling problems (N = 1,084) contacting the Connecticut Council on Problem Gambling Helpline.Results Of the 1,018 phone calls used in the logistic regression analyses, 168 (16.5%) were from older adults and 850 (83.5%) from younger adults. Age-related differences were observed in demographic features, types and patterns of gambling reported as problematic, gambling-related problems and psychiatric symptoms, substance use problems, patterns of indebtedness, and family histories of addictive disorders. Older as compared with younger adult problem gamblers were more likely to report having lower incomes, longer durations of gambling, fewer types of problematic gambling, and problems with casino slot machine gambling and less likely to report gambling-related anxiety, family problems, illegal behaviors and arrests, drug problems, indebtedness to bookies or acquaintances, family histories of drug abuse, and problems with casino table gambling.Conclusions Older as compared with younger adult problem gamblers calling a gambling helpline differ on many clinically relevant features. The findings suggest the need for improved and unique prevention and treatment strategies for older adults with gambling problems.     

Knowledge Life Cycle,Knowledge Inventory,and Knowledge Acquisition Strategies*

For a knowledge‐ and skill‐centric organization, the process of knowledge management encompasses three important and closely related elements: (i) task assignments, (ii) knowledge acquisition through training, and (iii) maintaining a proper level of knowledge inventory among the existing workforce. Trade‐off on choices between profit maximization in the short run and agility and flexibility in the long term is a vexing problem in knowledge management. In this study, we examine the effects of different training strategies on short‐term operational efficiency and long‐term workforce flexibility. We address our research objective by developing a computational model for task and training assignment in a dynamic knowledge environment consisting of multiple distinct knowledge dimensions. Overall, we find that organizational slack is an important variable in determining the effectiveness of training strategies. Training strategies focused on the most recent skills are found to be the preferred option in most of the considered scenarios. Interestingly, increased efficiencies in training can actually create preference conflict between employees and the firm. Our findings indicate that firms facing longer knowledge life cycles, higher slack in workforce capacity, and better training efficiencies actually face more difficult challenges in knowledge management.     

Development of a Dose‐Response Model for SARS Coronavirus

In order to develop a dose‐response model for SARS coronavirus (SARS‐CoV), the pooled data sets for infection of transgenic mice susceptible to SARS‐CoV and infection of mice with murine hepatitis virus strain 1, which may be a clinically relevant model of SARS, were fit to beta‐Poisson and exponential models with the maximum likelihood method. The exponential model (k= 4.1 × l0²) could describe the dose‐response relationship of the pooled data sets. The beta‐Poisson model did not provide a statistically significant improvement in fit. With the exponential model, the infectivity of SARS‐CoV was calculated and compared with those of other coronaviruses. The does of SARS‐CoV corresponding to 10% and 50% responses (illness) were estimated at 43 and 280 PFU, respectively. Its estimated infectivity was comparable to that of HCoV‐229E, known as an agent of human common cold, and also similar to those of some animal coronaviruses belonging to the same genetic group. Moreover, the exponential model was applied to the analysis of the epidemiological data of SARS outbreak that occurred at an apartment complex in Hong Kong in 2003. The estimated dose of SARS‐CoV for apartment residents during the outbreak, which was back‐calculated from the reported number of cases, ranged from 16 to 160 PFU/person, depending on the floor. The exponential model developed here is the sole dose‐response model for SARS‐CoV at the present and would enable us to understand the possibility for reemergence of SARS.     

A Bayesian approach to statistical inference in stochastic DEA

Stochastic DEA can deal effectively with noise in the non-parametric measurement of efficiency but unfortunately formal statistical inference on efficiency measures in not possible. In this paper, we provide a Bayesian approach to the problem organized around simulation techniques that allow for finite-sample inferences on efficiency scores. The new methods are applied to efficiency analysis of the Greek banking system for the period 1993–1999. The results show that the majority of the Greek banks operate close to best market practices.     

家庭政策的悖论

美国在制定“支持家庭”(family friendly)的社会政策方面要远远落后于欧洲发达的工业化民主国家,这是为人们所广泛公认的。即便如此,在2 0 0 0年,美国的人口出生率( 2 0 6‰)明显高于欧洲主要工业化国家的人口出生率(西班牙和意大利:1 2 2‰;英国:1 72‰;法国:1 74‰;德国:1 4 4‰;瑞典:1 5 4‰;荷兰:1 66‰)。1 996年,欧盟1 5国中平均每1 0 0 0人当中有5 1对男女结婚,明显低于美国每1 0 0 0人中8 8对的比例。就婚姻地位而言,欧洲国家有更多的人是采取自愿同居的方式生活,例如1 997年,在1 6～2 9岁的人群中,法国有48%的夫…     

Simultaneous Confidence Intervals for the Parameters of Pareto Distribution under Progressive Censoring

In this article, we consider the progressive Type II right censored sample from Pareto distribution. We introduce a new approach for constructing the simultaneous confidence interval of the unknown parameters of this distribution under progressive censoring. A Monte Carlo study is also presented for illustration. It is shown that this confidence region has a smaller area than that introduced by Ku? and Kaya (2007 Ku? , C. , Kaya , M. F. ( 2007 ). Estimation for the parameters of the Pareto distribution under progressive censoring . Commun. Statist. Theor. Meth. 36 : 1359 – 1365 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]).     

Moment Information for Probability Distributions,Without Solving the Moment Problem. I: Where is the Mode?

How much information does a small number of moments carry about the unknown distribution function? Is it possible to explicitly obtain from these moments some useful information, e.g., about the support, the modality, the general shape, or the tails of a distribution, without going into a detailed numerical solution of the moment problem? In this paper a theoretical result of Johnson and Rogers is generalized to be valid for all moment problems and is exploited to demonstrate that a few moments are able to provide us with valuable information about the position of the mode of an unknown (unimodal) distribution.     

IPPS Sampling Plans Excluding Adjacent Units

The concept of inclusion probability proportional to size sampling plans excluding adjacent units separated by at most a distance of m (≥ 1) units {IPPSEA plans} is introduced. IPPSEA plans ensure that the first-order inclusion probabilities of units are proportional to size measures of the units, while the second-order inclusion probabilities are zero for pairs of adjacent units separated by a distance of m units or less. IPPSEA plans have been obtained by making use of binary, proper, and unequireplicated block designs and linear programing approach. The performance of IPPSEA plans using Horvitz–Thompson estimator of population total has been compared with existing sampling plans such as simple random sampling without replacement (SRSWOR), balanced sampling plans excluding adjacent units {BSA (m) plans}, probability proportional to size with replacement, Hartley and Rao's plan (1962 Hartley , H. O. , Rao , J. N. K. ( 1962 ). Sampling with unequal probabilities and without replacement . Ann. Math. Statist. 33 : 350 – 374 .[Crossref] , [Google Scholar]), Rao et al.'s strategy (1962 Rao , J. N. K. , Hartley , H. O. , Cochran , W. G. ( 1962 ). On a simple procedure of unequal probability sampling without replacement . J. Roy. Statist. Soc. B 24 : 482 – 491 . [Google Scholar]), and Sampford's IPPS plan (1967 Sampford , M. R. ( 1967 ). On sampling without replacement with unequal probabilities of selection . Biometrika 54 ( 3 ): 499 – 513 .[Crossref], [PubMed] , [Google Scholar]) using a real life population. Unbiased estimation of Horvitz–Thompson estimator of population total is not possible in these types of plans because some of the second-order inclusion probabilities are zero. To resolve this problem, one approximate variance estimation technique has been suggested.