Natural laminar flow nacelle for transport aircraft

The potential of laminar flow nacelles for reducing installed engine/nacelle drag was studied. The purpose was twofold: to experimentally verify a method for designing laminar flow nacelles and to determine the effect of installation on the extent of laminar flow on the nacelle and on the nacelle pressure distributions. The results of the isolated nacelle tests illustrated that laminar flow could be maintained over the desired length. Installing the nacelles on wing/pylon did not alter the extent of laminar flow occurring on the nacelles. The results illustrated that a significant drag reduction was achieved with this laminar flow design. Further drag reduction could be obtained with proper nacelle location and pylon contouring

The Value of Demonstration in Human Maze Learning

In a first experiment, forty subjects were assigned to one of four groups. Each of these groups received one, two or three demonstrations, or no demonstration at all of a task on a bolt-head maze. It was found that number of demonstrations and reduction of errors per trial were positively related up to two demonstrations but no additional increment in performance appeared for three demonstrations. In a second experiment, error making by a demonstrator was contrasted with skilled demonstration. Three demonstrations with errors resulted in significantly fewer errors per trial than two demonstrations with errors. Three skilled errorless demonstration was nonsignificantly superior to three demonstrations with errors

Plant speciation in the Namib Desert : potential origin of a widespread derivative species from a narrow endemic

This research was funded in part by the award of a Natural Environment Research Council (NERC) CASE research studentship to J.J.M.Background:  Parapatric (or ‘budding’) speciation is increasingly recognised as an important phenomenon in plant evolution but its role in extreme (e.g. desert) environments is poorly documented.  Aims:  To test this speciation model in a hypothesised sister pair, the Southwest – North African disjunct Senecio flavus and its putative progenitor, the Namibian Desert endemic S. englerianus.  Methods:  Phylogenetic inferences were combined with niche divergence tests, morphometrics, and experimental-genetic approaches. We also evaluated the potential role of an African Dry Corridor (ADC) in promoting the hypothesised northward expansion of S. flavus (from Namibia), using palaeodistribution models.  Results:  Belonging to an isolated (potential ‘relict’) clade, the two morphologically distinct species showed pronounced niche divergence in Namibia and signs of digenic-epistatic hybrid incompatibility (based on F2 pollen fertility). The presence of ‘connate-fluked’ pappus hairs in S. flavus, likely increasing dispersal ability, is controlled by a single gene locus.  Conclusions:  Our results provide evidence for a possible (and rare) example of ‘budding’ speciation in which a wider-ranged derivative (S. flavus) originated at the periphery of a smaller-ranged progenitor (S. englerianus) in the Namib Desert region. The Southwest – North African disjunction of S. flavus could have been established by dispersal across intermediate ADC areas during periods of (Late) Pleistocene aridification.Publisher PDFPeer reviewe

Exascale Agent-Based Modelling for Policy Evaluation in Real-Time (ExAMPLER)

Exascale computing can potentially revolutionise the way in which we design and build agent-based models (ABM) through, for example, enabling scaling up, as well as robust calibration and validation. At present, there is no exascale computing operating with ABM (that we are aware of), but pockets of work using High Performance Computing (HPC). While exascale computing is expected to become more widely available towards the latter half of this decade, the ABM community is largely unaware of the requirements for exascale computing for agent-based modelling to support policy evaluation. This project will engage with the ABM community to understand what computing resources are currently used, what we need (both in terms of hardware and software) and to set out a roadmap by which to make it happen

Cost-effectiveness of a smoking cessation program after myocardial infarction

AbstractObjectives. The purpose of this study was to evaluate the cost-effectiveness of a smoking cessation program initiated after acute myocardial infarction.Background. The value of allocating health care resources to smoking cessation programs after myocardial infarction has not been compared with the value of other currently accepted interventions.Methods. A model was developed to examine the cost-effectiveness of a recently reported smoking cessation program after an acute myocardial infarction. The cost was estimated by considering the resources necessary to implement the program, and the effectiveness was expressed as discounted years of life saved. Years of life saved were estimated by modeling life expectancy using a single declining exponential approximation of life expectancy based on data from published reports.Results. The cost-effectiveness of the nurse-managed smoking cessation program was estimated to be $220/year of life saved. In a one-way sensitivity analysis, the cost-effectiveness of the program remained <$20,000/year of life saved if the program decreased the smoking rate by only 3/1,000 smokers (baseline assumption 26/100 smokers), or if the program cost as much as $8,840/smoker (baseline assumption$100). In a two-way sensitivity analysis, even if the cost of the program were as high as $2,000/participant, the cost-effectiveness of the program would be <$10,000/year of life saved so as the an program helped an additional 12 smokers quit for every 100 enrolled.Conclusions. Over a wide range of estimates of costs and effectiveness, a nurse-managed smoking cessation program after acute myocardial infarction is an extremely cost-effective intervention. This program is more cost-elective than beta-adrenergic antagonist therapy after myocardial infarction

The physical and chemical properties of electroless nickel-phosphorous alloys and low reflectance nickel-phosporous black surfaces

Novel insights into the manufacture of nickel-phosphorus black surfaces by chemical etching of electrolessdeposited Ni-P alloy has been achieved by examining the influence of pre-etch phosphorus composition and etching method on the resulting morphology, composition and reflectance of the black surface produced. An optimum phosphorus composition and etching regime to produce low reflectance blacks of 0.4% or lower in the visible region is proposed. Cross-sectional analysis of the etched surface has allowed, for the first time, an accurate determination of the scale of the enhanced morphologies produced and the thickness of the oxidised black layer itself. AFM studies have also provided information on the phase structure of the as-deposited Ni-P alloy

Electromagnetic Modelling of Raman Enhancement from Nanoscale Structures as a Means to Predict the Efficacy of SERS Substrates

The requirement to optimise the balance between signal enhancement and reproducibility in surface enhanced Raman spectroscopy (SERS) is stimulating the development of novel substrates for enhancing Raman signals. This paper describes the application of finite element electromagnetic modelling to predict the Raman enhancement produced from a variety of SERS substrates with differently sized, spaced and shaped morphologies with nanometre dimensions. For the first time, a theoretical comparison between four major generic types of SERS substrate (including metal nanoparticles, structured surfaces, and sharp tips) has been performed and the results are presented and discussed. The results of the modelling are consistent with published experimental data from similar substrates

Is There a Role for Benefit-Cost Analysis in Environmental, Health, and Safety Regulation?

Benefit-cost analysis has a potentially important role to play in helping inform regulatory decision-making, although it should not be the sole basis for such decision-making. This paper offers eight principles on the appropriate use of benefit-cost analysis.Environment, Health and Safety, Regulatory Reform

Benefit-Cost Analysis in Environmental, Health, and Safety Regulation: A Statement of Principles

Benefit-cost analysis can play a very important role in legislative and regulatory policy debates on improving the environment, health, and safety. It can help illustrate the tradeoffs that are inherent in public policymaking as well as make those tradeoffs more transparent. It can also help agencies set regulatory priorities. Benefit-cost analysis should be used to help decisionmakers reach a decision. Contrary to the views of some, benefit-cost analysis is neither necessary nor sufficient for designing sensible public policy. If properly done, it can be very helpful to agencies in the decisionmaking process. Decisionmakers should not be precluded from considering the economic benefits and costs of different policies in the development of regulations. Laws that prohibit costs or other factors from being considered in administrative decisionmaking are inimical to good public policy. Currently, several of the most important regulatory statutes have been interpreted to imply such prohibitions. Benefit-cost analysis should be required for all major regulatory decisions, but agency heads should not be bound by a strict benefit-cost test. Instead, they should be required to consider available benefit-cost analyses and to justify the reasons for their decision in the event that the expected costs of a regulation far exceed the expected benefits. Agencies should be encouraged to use economic analysis to help set regulatory priorities. Economic analyses prepared in support of particularly important decisions should be subjected to peer review both inside and outside government. Benefits and costs of proposed major regulations should be quantified wherever possible. Best estimates should be presented along with a description of the uncertainties. Not all benefits or costs can be easily quantified, much less translated into dollar terms. Nevertheless, even qualitative descriptions of the pros and cons associated with a contemplated action can be helpful. Care should be taken to ensure that quantitative factors do not dominate important qualitative factors in decisionmaking. The Office of Management and Budget, or some other coordinating agency, should establish guidelines that agencies should follow in conducting benefit-cost analyses. Those guidelines should specify default values for the discount rate and certain types of benefits and costs, such as the value of a small reduction in mortality risk. In addition, agencies should present their results using a standard format, which summarizes the key results and highlights major uncertainties.