Studies of random demands on network costs

When network demands are uncertain, a planner might design a network based on some nominal set of point‐to‐point demands, and later be faced with a different set of offered demands. To accommodate the offered demands, modification of the network may be required. Given this scenario, it seems natural to question how these modification costs might affect the overall cost. To address such questions, we study the effects of random demands on network costs. In this study, we design a network based on nominal demands, generate random demands based on the nominal demands, and then modify the designed network to carry the random demands. We generate the offered demands randomly from four different distributions. For each demand distribution we perform 300 simulations. This paper describes our observations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Transdermal nitroglycerin: clinical and pharmacokinetic consequences of renewing the patch and the application site

OBJECTIVE: We examined whether nitroglycerin (glyceryl trinitrate, GTN) patch treatment for 24 h could induce local cutaneous changes that impaired drug delivery and clinical efficacy. METHODS: Twenty angina patients were exercise-tested after 2 and 24 h of treatment and then 2 h after patch renewal. The patch was either renewed on a new skin location or on the previous application site in a randomised, double-blind, cross-over protocol. GTN plasma concentrations and finger plethysmography were obtained before and after each exercise test. RESULTS AND CONCLUSIONS: The clinical efficacy, the effect seen on plethysmography and the GTN plasma concentrations tended to increase after patch renewal, regardless of the application site of the renewed patch. Hence, cutaneous changes of clinical importance could not be demonstrated.     

Employee response to a company-sponsored program of colorectal and prostate cancer screening

Studies done in the mid-1970s documented increased risk for respiratory cancer and leukemia among employees in a chemical company manufacturing plant where chloromethyl ethers were used in production from 1948 to 1971. In the late 1980s, the company informed current and former employees about the results of follow-up studies which showed a moderation of risk of respiratory cancer and leukemia. New data showing elevated rates of mortality from colorectal, prostate, bladder, and pancreatic cancer in the population were also reported. Via mailed correspondence, the company made a no-cost program of colorectal and prostate cancer screening available to employees upon request; and information about bladder and pancreatic cancer was made available. Thirteen percent of employees in the population indicated interest in colorectal and prostate cancer screening (response). Thirty-one percent of these responders were screened (adherence). Multivariate analyses showed that education and length of employment in the plant were positively associated with response. Being white was positively associated with response for younger workers; while among older workers being male was positively associated with response. In terms of adherence, we found that older, more highly educated workers were more likely to have a screening examination. Findings indicate that employee participation in workplace-sponsored colorectal and prostate cancer screening can vary according to worker sociodemographic factors and length of employment in areas of potential exposure.     

Effect of aspirin on prostaglandin E2 and leukotriene B4 production in human colonic mucosa from cancer patients

Elderly persons typically show diminished immune responsiveness to influenza vaccination. Chiron Vaccines has developed a novel oil-in-water adjuvant emulsion, MF59, to enhance vaccine immunogenicity without compromising safety and tolerability. MF59 was shown to augment influenza vaccine immunogenicity in senescent mice. Subsequently, eight similarly designed, randomized, controlled clinical trials of a subunit influenza vaccine combined with MF59 were conducted between 1992 and 1995 in 1807 elderly volunteers (> or = 65 years old). Mild, transient, injection-site reactions were increased with MF59, but systemic reactions generally were not. For two of the three vaccine antigens (B and A/H3N2), postimmunization haemagglutinin inhibition geometric mean titres were statistically significantly higher with MF59. During influenza season, fewer deaths occurred among MF59 recipients. This development programme demonstrates how an adjuvant that stimulates effectors associated with immunosenescence can improve the performance of an existing vaccine in elderly persons.     

Information Technology Measurement and Testing Activities at NIST

Our high technology society continues to rely more and more upon sophisticated measurements, technical standards, and associated testing activities. This was true for the industrial society of the 20th century and remains true for the information society of the 21st century. Over the last half of the 20th century, information technology (IT) has been a powerful agent of change in almost every sector of the economy. The complexity and rapidly changing nature of IT have presented unique technical challenges to the National Institute of Standards and Technology (NIST) and to the scientific measurement community in developing a sound measurement and testing infrastructure for IT. This measurement and testing infrastructure for the important non-physical and non-chemical properties associated with complex IT systems is still in an early stage of development. This paper explains key terms and concepts of IT metrology, briefly reviews the history of the National Bureau of Standards/National Institute of Standards and Technology (NBS/NIST) in the field of IT, and reviews NIST’s current capabilities and work in measurement and testing for IT. It concludes with a look at what is likely to occur in the field of IT over the next ten years and what metrology roles NIST is likely to play.     

Factors associated with food workers working while experiencing vomiting or diarrhea

This study sought to determine the frequency with which food workers said they had worked while experiencing vomiting or diarrhea, and to identify restaurant and worker characteristics associated with this behavior. We conducted interviews with food workers (n=491) and their managers (n=387) in the nine states that participate in the Centers for Disease Control and Prevention's Environmental Health Specialists Network. Restaurant and worker characteristics associated with repeatedly working while experiencing vomiting or diarrhea were analyzed via multivariable regression. Fifty-eight (11.9%) workers said they had worked while suffering vomiting or diarrhea on two or more shifts in the previous year. Factors associated with workers having worked while experiencing vomiting or diarrhea were (i) high volume of meals served, (ii) lack of policies requiring workers to report illness to managers, (iii) lack of on-call workers, (iv) lack of manager experience, and (v) workers of the male gender. Our findings suggest that policies that encourage workers to tell managers when they are ill and that help mitigate pressures to work while ill could reduce the number of food workers who work while experiencing vomiting or diarrhea.