Methods of Determining Thermal Accommodation Coefficients from Free Molecular Flow Heat Transfer Data

Heat transfer in rarefied gases, a previously little investigated subject, has undergone advances in the past few years due to increased areas of application. Among new areas of application are the insulation of booster propellant storage vessels and heat transfer to exterior surfaces of space vehicles. Low density heat transfer is subdivided into several regimes with the Knudsen number, Kn (The ration of mean free path to characteristic dimension of the system) serving as the criteria for designation.\u27 At sufficiently low pressures Kn becomes large compared with unity. For Kn greater than about 3, intermolecular collisions in a gas become negligible compared with gas molecule - boundary collisions. This is referred to as the free molecule flow region of gas dynamics and heat conduction. Heat conducted between surfaces separated by a gas with Kn\u3e3 occurs predominately by the mechanism of thermal exchange by direct molecule - wall collisions

A method of determining where to target surveillance efforts in heterogeneous epidemiological systems

The spread of pathogens into new environments poses a considerable threat to human, animal, and plant health, and by extension, human and animal wellbeing, ecosystem function, and agricultural productivity, worldwide. Early detection through effective surveillance is a key strategy to reduce the risk of their establishment. Whilst it is well established that statistical and economic considerations are of vital importance when planning surveillance efforts, it is also important to consider epidemiological characteristics of the pathogen in question—including heterogeneities within the epidemiological system itself. One of the most pronounced realisations of this heterogeneity is seen in the case of vector-borne pathogens, which spread between ‘hosts’ and ‘vectors’—with each group possessing distinct epidemiological characteristics. As a result, an important question when planning surveillance for emerging vector-borne pathogens is where to place sampling resources in order to detect the pathogen as early as possible. We answer this question by developing a statistical function which describes the probability distributions of the prevalences of infection at first detection in both hosts and vectors. We also show how this method can be adapted in order to maximise the probability of early detection of an emerging pathogen within imposed sample size and/or cost constraints, and demonstrate its application using two simple models of vector-borne citrus pathogens. Under the assumption of a linear cost function, we find that sampling costs are generally minimised when either hosts or vectors, but not both, are sampled

Risk-based management of invading plant disease

- Effective control of plant disease remains a key challenge. Eradication attempts often involve removal of host plants within a certain radius of detection, targeting asymptomatic infection. Here we develop and test potentially more effective, epidemiologically motivated, control strategies, using a mathematical model previously fitted to the spread of citrus canker in Florida. - We test risk-based control, which preferentially removes hosts expected to cause a high number of infections in the remaining host population. Removals then depend on past patterns of pathogen spread and host removal, which might be nontransparent to affected stakeholders. This motivates a variable radius strategy, which approximates risk-based control via removal radii that vary by location, but which are fixed in advance of any epidemic. - Risk-based control outperforms variable radius control, which in turn outperforms constant radius removal. This result is robust to changes in disease spread parameters and initial patterns of susceptible host plants. However, efficiency degrades if epidemiological parameters are incorrectly characterised. - Risk-based control including additional epidemiology can be used to improve disease management, but it requires good prior knowledge for optimal performance. This focuses attention on gaining maximal information from past epidemics, on understanding model transferability between locations and on adaptive management strategies that change over time.Part of this work was funded by the USDA-APHIS Farm Bill; C.A.G. acknowledges support from USDA-APHIS

Transient Response of a Hollow Cylindrical-Cross-Section Solid Sensible Heat: Storage Unit- Single Fluid

plosion which have been interpreted in terms of the kinetic theory of nucleation can likewise be viewed in terms of film boiling destabilization with attendant fine scale fragmentation of the hot material. Vol. 77, No. 23, 1973, pp. 2730-2736 26 Cronenberg, A. W., Benz, R., to be published, Advances in Nuclear Science and Technology, 1978. 27 Anderson, R. P., Armstrong, D. R., ASME Meeting on Nuclear Reactor Safety Heat Transfer, Atlanta, Ga., Nov. 1977. 28 Henry, R. E., Fauske, H. K., McUmber, L. M., Proceedings of ANS Conference on Fast Reactor Safety, Chicago, 111. (Oct. 1976). Conclusions 29 Fauske, H. K., Nuclear Science and Engineering, Vol. 51, 1973, pp. 95-101. 30 Fauske, H. K., Reactor Technology, Vol. 15, No. 4, 1972-1973 3

Due Process—Revocation of Driver’s License: \u3ci\u3eStauffer v. Weedlun\u3c/i\u3e, 188 Neb. 105, 195 N.W.2.d 218 (1972)

In Stauffer v. Weedlun, the Nebraska Supreme Court held revocation of a driver\u27s license upon accumulation of twelve or more traffic violation points meets due process requirements despite the absence of statutory provisions for prior hearing and notice to the driver. The decision merits further consideration in light of an earlier case, Bell v. Burson, in which the United States Supreme Court held due process was violated when a driver\u27s license was suspended pursuant to a financial responsibility law, because of lack of a prior notice and an opportunity for a hearing on the driver\u27s possible liability. This casenote considers the grounds on which the Nebraska Supreme Court distinguished revocation of a driver\u27s license for traffic violations from suspension pursuant to financial responsibility laws. Specifically, analysis will focus on the Nebraska Supreme Court\u27s reliance on the emergency doctrine and the court\u27s decision that a judicial stay of the order of revocation pending judicial review affords the licensee due process