The numerical solution of certain differential equations occurring in Crocco's theory of the laminar boundary layer

A numerical method is described for the solution of certain differential equations which result from the application of Crocco’s transformation to the laminar boundary layer equations appropriate to high supersonic Mach numbers. (i.e. at hypersonic speeds). Continues

The view from elsewhere: perspectives on ALife Modeling

Many artificial life researchers stress the interdisciplinary character of the field. Against such a backdrop, this report reviews and discusses artificial life, as it is depicted in, and as it interfaces with, adjacent disciplines (in particular, philosophy, biology, and linguistics), and in the light of a specific historical example of interdisciplinary research (namely cybernetics) with which artificial life shares many features. This report grew out of a workshop held at the Sixth European Conference on Artificial Life in Prague and features individual contributions from the workshop's eight speakers, plus a section designed to reflect the debates that took place during the workshop's discussion sessions. The major theme that emerged during these sessions was the identity and status of artificial life as a scientific endeavor

Estimating the health benefits of progeny extraction units as a means of reducing exposure to radon

Radon exposure to the general public can be reduced by preventing entry of radon gas into buildings using a passive radon-proof membrane or an active sump and pump system. However, a significant majority of the radiation dose delivered is from the decay products of radon rather than from the gas itself. These decay products (also referred to as progeny) are present in indoor air, with an equilibrium factor – a measure of the ratio of progeny to radon gas – of between 0.4 to 0.5. As a result, systems which extract radon progeny from the air by filtering have been promoted as means of reducing exposure to the general population. The European Community Radon Software (ECRS) offers a means of estimating lung-cancer risk associated with an individual’s exposure to radon, and includes the possibility of estimating the health risk from different proportions of radon gas and its progeny by varying the value of the Equilibrium Factor. This software was used to estimate the health benefits associated with reduced decay products in differing concentrations of radon gas. The results were compared to health benefits expected if the risk was reduced by the standard method of reducing the radon gas concentration below the Action Level, which in the UK is 200 Bq·m-3 for domestic properties. These calculations showed that there is the potential for efficient extraction units to provide the necessary dose and risk reduction where initial average radon gas concentrations are up to 800 Bq·m-3. However, above 1000 Bq·m-3, such systems cannot reduce the health risk sufficiently to reach levels comparable to those resulting from radon gas reduction to below the Action Leve

Using e-mail recruitment and an online questionnaire to establish effect size: A worked example

Background\ud Sample size calculations require effect size estimations. Sometimes, effect size estimations and standard deviation may not be readily available, particularly if efficacy is unknown because the intervention is new or developing, or the trial targets a new population. In such cases, one way to estimate the effect size is to gather expert opinion. This paper reports the use of a simple strategy to gather expert opinion to estimate a suitable effect size to use in a sample size calculation.\ud \ud Methods\ud Researchers involved in the design and analysis of clinical trials were identified at the University of Birmingham and via the MRC Hubs for Trials Methodology Research. An email invited them to participate.\ud \ud An online questionnaire was developed using the free online tool 'Survey Monkey©'. The questionnaire described an intervention, an electronic participant information sheet (e-PIS), which may increase recruitment rates to a trial. Respondents were asked how much they would need to see recruitment rates increased by, based on 90%. 70%, 50% and 30% baseline rates, (in a hypothetical study) before they would consider using an e-PIS in their research.\ud \ud Analyses comprised simple descriptive statistics.\ud \ud Results\ud The invitation to participate was sent to 122 people; 7 responded to say they were not involved in trial design and could not complete the questionnaire, 64 attempted it, 26 failed to complete it. Thirty-eight people completed the questionnaire and were included in the analysis (response rate 33%; 38/115). Of those who completed the questionnaire 44.7% (17/38) were at the academic grade of research fellow 26.3% (10/38) senior research fellow, and 28.9% (11/38) professor. Dependent upon the baseline recruitment rates presented in the questionnaire, participants wanted recruitment rate to increase from 6.9% to 28.9% before they would consider using the intervention.\ud \ud Conclusions\ud This paper has shown that in situations where effect size estimations cannot be collected from previous research, opinions from researchers and trialists can be quickly and easily collected by conducting a simple study using email recruitment and an online questionnaire. The results collected from the survey were successfully used in sample size calculations for a PhD research study protocol.\ud \u

Pharmacological assessment of ibuprofen arginate on platelet aggregation and colon cancer cell killing

This work was funded in part by grants from the Wellcome Trust (0852551Z108/Z, to J.A.M.) and British Heart Foundation (FS/16/1/31699, to NSK). SM is a recipient of a PhD award from the King of Saud University, AT is a recipient of a MRC PhD studentship

Investigating the role of endothelin receptor subtypes in the response to vascular injury

Neointimal hyperplasia, the proliferative growth of the innermost layer of the blood vessel wall, is a key process in the response to vascular injury, underlying conditions such as post-interventional restenosis and vein/arterial graft disease. One of the many mediators implicated in this process is endothelin-1 (ET-1), a potent vasoconstrictor with pro-inflammatory and pro-mitogenic actions, which acts through ETA and ETB receptor subtypes. It is well established that ET-1 increases, and ETA blockade reduces, neointima formation following vascular injury. The role of ETB is less clear because these receptors mediate potentially beneficial actions in endothelial cells (EC; such as nitric oxide production, and ET-1 clearance) but detrimental effects elsewhere (such as vascular smooth muscle) and it has been recently reported that non-cell-specific ETB deficiency is associated with increased neointimal lesion size following injury. The work described in this thesis addressed the hypothesis that endogenous ET-1 contributes to neointimal hyperplasia by activation of the ETA receptor, and that this action is moderated by concurrent activation of the ETB receptor expressed in EC. The role of ET receptors in neointimal lesion development was assessed using two models of femoral arterial injury in the mouse: (i) an established method of intraluminal wire-injury, and (ii) adaptation of a model of ligation injury that induces robust neointimal lesion formation without physical damage to the endothelium. Lesion development was assessed using standard histological techniques and this was augmented by development of quantitative optical projection tomography (OPT) to allow three-dimensional analysis of lesions. The role of ETA and ETB receptors in these models was addressed using suitable pharmacological ET receptor antagonists. Following wire-injury, selective ETB blockade (A192621; 30mg.kg-1.day-1; 35 days) increased lesion size and blood pressure without significant altering lesion composition. In contrast, selective ETA blockade (atrasentan; 10mg.kg-1.day-1; 35 days) reduced lesion size and blood pressure. Combined ETA+ETB antagonism had no effect on lesion size, despite reducing blood pressure, and reducing collagen content of the lesions. In the ligation model, neither ETA selective, ETB selective nor ETA+ETB blockade altered lesion size as assessed by standard histology but analysis by OPT indicated that ETA blockade, with or without concurrent ETB blockade, reduced lesion volume. The influence of ETB receptors expressed by ECs on lesion formation was addressed using EC-specific ETB knockout mice. Small vessel myography indicated that endothelium-dependent relaxation was unaltered in femoral arteries from these mice. In addition, no effect on lesion size or rate of development was observed in either wire- or ligation-injury models of neointima formation (although subtle effects on lesion and medial composition were apparent after intra-luminal injury). These results indicate that ETB receptor activation can moderate the detrimental actions of the ETA receptor on neointimal lesion progression, and that this role is dependent on the mode of vascular injury. Furthermore, in this setting, this beneficial action is not primarily mediated by ETB expressed by EC, suggesting that ETB in other cell types can reduce lesion development through another, unidentified mechanism. Therefore, while both ETA selective and non-selective ETA/B antagonists are currently in clinical use, in conditions where similar arterial remodelling processes occur, selective ETA receptor antagonists might be preferred

Comparison of optical model results from a microscopic Schr\"odinger approach to nucleon-nucleus elastic scattering with those from a global Dirac phenomenology

Comparisons are made between results of calculations for intermediate energy nucleon-nucleus scattering for 12C, 16O, 40Ca, 90Zr, and 208Pb, using optical potentials obtained from global Dirac phenomenology and from a microscopic Schr\"odinger model. Differential cross sections and spin observables for scattering from the set of five nuclei at 65 MeV and 200 MeV have been studied to assess the relative merits of each approach. Total reaction cross sections from proton-nucleus and total cross sections from neutron-nucleus scattering have been evaluated and compared with data for those five targets in the energy range 20 MeV to 800 MeV. The methods of analyses give results that compare well with experimental data in those energy regimes for which the procedures are suited.Comment: 22 pages, 12 figure