The development of a quick-running prediction tool for the assessment of human injury owing to terrorist attack within crowded metropolitan environments

In the aftermath of the London '7/7' attacks in 2005, UK government agencies required the development of a quick-running tool to predict the weapon and injury effects caused by the initiation of a person borne improvised explosive device (PBIED) within crowded metropolitan environments. This prediction tool, termed the HIP (human injury predictor) code, was intended to:--assist the security services to encourage favourable crowd distributions and densities within scenarios of 'sensitivity'; --provide guidance to security engineers concerning the most effective location for protection systems; --inform rescue services as to where, in the case of such an event, individuals with particular injuries will be located; --assist in training medical personnel concerning the scope and types of injuries that would be sustained as a consequence of a particular attack; --assist response planners in determining the types of medical specialists (burns, traumatic amputations, lungs, etc.) required and thus identify the appropriate hospitals to receive the various casualty types. This document describes the algorithms used in the development of this tool, together with the pertinent underpinning physical processes. From its rudimentary beginnings as a simple spreadsheet, the HIP code now has a graphical user interface (GUI) that allows three-dimensional visualization of results and intuitive scenario set-up. The code is underpinned by algorithms that predict the pressure and momentum outputs produced by PBIEDs within open and confined environments, as well as the trajectories of shrapnel deliberately placed within the device to increase injurious effects. Further logic has been implemented to transpose these weapon effects into forms of human injury depending on where individuals are located relative to the PBIED. Each crowd member is subdivided into representative body parts, each of which is assigned an abbreviated injury score after a particular calculation cycle. The injury levels of each affected body part are then summated and a triage state assigned for each individual crowd member based on the criteria specified within the 'injury scoring system'. To attain a comprehensive picture of a particular event, it is important that a number of simulations, using what is substantively the same scenario, are undertaken with natural variation being applied to the crowd distributions and the PBIED output. Accurate mathematical representation of such complex phenomena is challenging, particularly as the code must be quick-running to be of use to the stakeholder community. In addition to discussing the background and motivation for the algorithm and GUI development, this document also discusses the steps taken to validate the tool and the plans for further functionality implementation.     

Sorption of plutonium, americium and fission products from reprocessing effluents using Rhizopus arrhizus

Rhizopus arrhizus biomass removed more than 95% of 239Pu, 241Am, 95Zr, 144Ce and 152+154Eu from different waste streams generated in Purex as well as Truex processes after suitable adjustment of pH. © Rapid Science Ltd. 1998     

Estimates of absolute cause-specific risk in cohort studies

In this paper we study methods for estimating the absolute risk of an event c1 in a time interval [t1, t2], given that the individual is at risk at t1 and given the presence of competing risks. We discuss some advantages of absolute risk for measuring the prognosis of an individual patient and some difficulties of interpretation for comparing two treatment groups. We also discuss the importance of the concept of absolute risk in evaluating public health measures to prevent disease. Variance calculations permit one to gauge the relative importance of random and systematic errors in estimating absolute risk. Efficiency calculations were also performed to determine how much precision is lost in estimating absolute risk with a nonparametric approach or with a flexible piecewise exponential model rather than a simple exponential model, and other calculations indicate the extent of bias that arises with the simple exponential model when that model is invalid. Such calculations suggest that the more flexible models will be useful in practice. Simulations confirm that asymptotic methods yield reliable variance estimates and confidence interval coverages in samples of practical size.     

Estimates of methane emissions in Beijing using a backward trajectory inversion model

Abstract

From July to December 2000, ambient methane concentrations were continuously monitored at one sampling site 92 m above ground in Beijing city. Together with meteorological data measured at 22 municipal stations, a backward trajectory inversion model was developed to calculate methane emissions in the city. Model results were compared with a methane emission inventory established with updated emission factors and intensive survey of sources.

From the source inventory, the total methane emissions were estimated to be 296.4Gg/yr, while municipal solid waste and fossil fuel account for 54.5% and 32.4% of total emissions. This showed that methane emissions in Beijing were dominated by anthropogenic sources. The inversion model described real-time methane emitted into the mixing layer along a backward trajectory path and also the exchange between reservoir layer and mixing layer. The Singular Value Decomposition (SVD) matrix inversion technique was used to calculate the methane emissions in each grid in the simulated region. The source distribution and quantitative results from model agreed well with the emission inventory, and the largest uncertainty in it was the distribution of methane emission from coal mines due to lack of trajectories covering coal mine areas.     

Estimates of survival of stream-dwelling brown trout using

Estimated monthly apparent survival of stream-dwelling brown trout Salmo trutta in south-east Norway was higher in winter than in summer, and lower in Alpine bullhead Cottus poecilopus sites than in allopatric sites. Apparent survival denotes true survival x local site fidelity. Emigration may also explain differences in apparent survival. All brown trout included in this Study were at least 1 year old.     

Oral contraception and risk of a cerebral thromboembolic attack: results of a case-control study.

OBJECTIVE--To assess the risk of cerebral thromboembolism in women using low dose oral contraceptives. DESIGN--A retrospective case-control study. SETTING--All Danish medical, neurological, neurosurgical, and gynaecological departments. SUBJECTS--All 794 women in Denmark aged 15-44 who had suffered a cerebral thromboembolic attack during 1985-9 and 1588 age matched randomly selected controls. RESULTS--Of 692/1584 case/control questionnaires sent out, 590/1396 (85.3%/88.1%) were returned. Among the cases, 15 refused to participate, 69 had a revised or unreliable diagnosis, 40 had had thromboembolic disease previously, 13 were pregnant, and 152 had a disease predisposing to a cerebral thromboembolic attack. Of the 323 cases without a known predisposition, 320 reported use or non-use of oral contraception. Among the 1396 controls, eight refused to participate, were mentally retarded, or lived abroad; 18 returned an uncompleted questionnaire; 17 had had thromboembolic disease previously; 31 were pregnant; and 130 had a disease predisposing to a cerebral thromboembolic attack. Thus 1198 non-predisposed controls were available, among whom 1197 reported use or non-use of oral contraception. Among the 320 cases, 116 (36.3%) were oral contraceptive users at the time of the cerebral thromboembolic attack. By comparison there were 191 users (16.0%) among the 1197 controls, giving a crude odds ratio of 3.0. After multivariate analysis, including confounder control for age, smoking, years of schooling, and trend in use of different types of oral contraceptives during 1985-90, pills containing 50 micrograms oestrogen were associated with an odds ratio for cerebral thromboembolic attack of 2.9 (95% confidence interval 1.6 to 5.4), those containing 30-40 micrograms oestrogen an odds ratio of 1.8 (1.1 to 2.9), those containing progestogen only an odds ratio of 0.9 (0.4 to 2.4). The odds ratio did not change with increasing age or with duration of oral contraceptive use. A 50% increased risk of a cerebral thromboembolic attacks among cigarette smokers (after confounder control) was independent of oral contraception status and age. CONCLUSION--Low dose oral contraceptives are associated with an increased risk of cerebral thromboembolic attack. Combined or sequential pills containing 30-40 micrograms oestrogen are associated with a one third reduced risk compared with preparations containing 50 micrograms oestrogen. Progestogen only pills did not increase the risk of a cerebral thromboembolic attack.     

Reduction of Delia radicum attack in field brassicas using a vertical barrier

According to life‐history theory, longer development time may result in bigger adults. However, reaction norms describing age and size at maturity often follow an L‐shaped form. This relationship is attributable to the simple notion that slowly growing individuals may not lengthen their development excessively after the maturation decision has been made, for example, when development is time limited in seasonal environments. In arthropods, growth occurs within instars, and thus the optimal growth strategy might be mediated by the phenotypic adjustment of instar numbers. We studied the relationship between age and size at maturity of a lichen‐feeding moth, Eilema depressum (Esper) (Lepidoptera: Arctiidae: Lithosiinae), and the variability of instar numbers in relation to achieved adult body mass and time used for maturation. A positive relationship between age and size at maturity was found across developmental pathways and a negative one within the developmental pathways. Directly developing larvae had higher growth rates, attained smaller pupal mass, and passed fewer instars than larvae maturing after overwintering. Host quality did not affect whether larvae matured during the remaining or the next season. High variation in the number of instars together with variable growth rates indicates high plasticity in adaptation to varying environmental conditions. Our results also confirm previous results that instar number variability may be a key characteristic mediating age and size at maturity in insects.     

Estimates of genetic parameters and breeding values from western larch open-pollinated families using marker-based relationship

The availability and affordability of genetic markers made it possible to estimate quantitative genetic parameters without mating designs' structured pedigree. Here, we compared 4-year height's heritability and individuals' breeding values for a western larch common-garden population of 1,418 offspring representing 15 open-pollinated families from a 41-clone seed orchard using (a) classical pedigree models such as half- and full-sib families and (b) a molecular marker-based pedigree-free model using four pair-wise relationship estimation methods using eight informative SSR markers. The results highlighted the commonly observed inflated estimates of genetic parameters often obtained from half-sib analyses, as well as demonstrating some of the full-sib analyses' caveats. The pedigree reconstruction permitted the identification of selfed individuals, thus allowing evaluating the impact of selfing on marker-based genetic parameter estimation. The results demonstrated the utility of marker-based methods as an alternative to the classical pedigree-based approaches. Unlike the pedigree-based methods, the marker-based approach allowed better partitioning the variance components as well as separating the non-additive and additive genetic variance. The theoretical underpinning of the marker-based approach was discussed.     

Mathematical elements of attack risk analysis for mountain pine beetles

Three different mathematical approaches are combined to develop a spatial framework in which risk of mountain pine beetle (MPB) attack on individual hosts may be assessed. A density-based partial differential equation model describes the dispersal and focusing behavior of MPB. A local projection onto a system of ordinary differential equations predicts the consequences of the density equations at individual hosts. The bifurcation diagram of these equations provides a natural division into categories of risk for each host. A stem-competition model links host vigor to stand age and demographics. Coupled together, these models illuminate spatial risk structures which may also shed light on the role of climatic variables in population outbreaks. Preliminary results suggest that stand microclimate has much greater influence on risk of attack than host vigor and stand age.     

Estimates of Survival from Radiotelemetry: a Response to Guthery and Lusk

Abstract: Radiotelemetry has become an important and frequently used tool in wildlife research. Inferences drawn from radiotelemetry data depend on the assumption that the radiotransmitters are not influencing parameter(s) of interest. An article by Guthery and Lusk (2004) in the Wildlife Society Bulletin questioned the validity of this assumption for estimating survival rates of northern bobwhites (Colinus virginianus) using radiotelemetry data. In this evaluation, we address technical and philosophical flaws in Guthery and Lusk's (2004) critique of northern bobwhite studies utilizing radiotelemetry. They concluded that biologists should be skeptical of radiotelemetry studies and they advised researchers to design studies to address potential biases caused by radiotransmitters using independent data. Although we agree that researchers are responsible for testing key assumptions of their techniques, we believe Guthery and Lusk's (2004) conclusions were not well supported and were based on tenuous assumptions. Guthery and Lusk (2004) calculated the level of productivity (given as a fall age ratio) required to balance a simple population model that contained published estimates of annual survival and assumed an annual finite population growth rate of 1.0. We review their population model and show that the relationship between an annual survival rate and fall age ratio is nonlinear. This nonlinearity can lead to biased estimates of a fall age ratio, especially at lower values of annual survival. We also question the validity of using fall age ratios as an estimator of productivity. Further, we suggest that this assessment of a radiotransmitter effect from a survival rate itself is not appropriate. This rate can be depressed (or elevated) for a variety of reasons not related to the influence of radiotransmitters. In addition, Guthery and Lusk (2004) assumed that daily survival rates (as calculated from both annual and seasonal published estimates) were constant throughout the year; thus, they scaled daily survival rates from seasonal to annual estimates. Further, their meta-analysis was hindered by temporal pseudoreplication and a lack of independence among the observations used in the analysis. We conclude the weight of the evidence presented by Guthery and Lusk (2004) is not as strong as they claim because it fails to meet the test of sufficient causation. While scientists should always be skeptical and critical of assumptions of all methods employed in wildlife research, more rigorous tests are necessary before we discredit a valuable technique without sufficient empirical evidence.     

Early risk of stroke after a transient ischemic attack in patients with internal carotid artery disease

BackgroundTransient ischemic attacks (TIAs) often herald a stroke, but little is known about the acute natural history of TIAs. Our objective was to quantify the early risk of stroke after a TIA in patients with internal carotid artery disease.MethodsUsing patient data from the medical arm of the North American Symptomatic Carotid Endarterectomy Trial, we calculated the risk of ipsilateral stroke in the territory of the symptomatic internal carotid artery within 2 and 90 days after a first-recorded hemispheric TIA. We also studied similar outcomes among patients in the trial who had a first-recorded completed hemispheric stroke.ResultsFor patients with a first-recorded hemispheric TIA (n = 603), the 90-day risk of ipsilateral stroke was 20.1% (95% confidence interval [CI] 17.0%–23.2%), higher than the 2.3% risk (95% CI 1.0%–3.6%) for patients with a hemispheric stroke (n = 526). The 2-day risks were 5.5% and 0.0%, respectively. Patients with more severe stenosis of the internal carotid artery (> 70%) appeared to be at no greater risk of stroke than patients with lesser degrees of stenosis (adjusted hazard ratio 1.1, 95% CI 0.7–1.7). Infarct on brain imaging (adjusted hazard ratio 2.1, 95% CI 1.5–3.0) and the presence of intracranial major-artery disease (adjusted hazard ratio 1.9, 95% CI 1.3-2.7) doubled the early risk of stroke in patients with a hemispheric TIA.InterpretationPatients who had a hemispheric TIA related to internal carotid artery disease had a high risk of stroke in the first few days after the TIA. Early risk of stroke was not affected by the degree of internal carotid artery stenosis.A transient ischemic attack (TIA) is a common neurological condition that is seen by all physician groups including family and emergency physicians, internists, vascular surgeons, and neurologists. In Canada, half a million adults aged 18 and over have been diagnosed with a TIA.¹ Presenting symptoms vary depending on which arterial supply is compromised, but they commonly consist of a brief episode of weakness, numbness, loss of vision or speech difficulty with complete recovery.Atherosclerotic disease of the carotid arteries outside the cranial cavity has long been recognized as the most common source of emboli that then travel to the brain causing stroke.^2,3,4 TIAs are often early warning signs of atherosclerotic disease. About 10% of patients with a TIA presenting to California emergency departments returned to the emergency department with a stroke within 90 days.⁵ In half of the patients, the stroke occurred within the first 48 hours after the TIA. Similar 90-day results have been observed in earlier community-based studies.^6,7,8 However, these studies all included some patients who had emboli from heart lesions or arrhythmias and some patients who had small-vessel disease as a cause of their TIA.Although several large stroke-prevention trials among patients with TIAs^{9,10,11,12,13,14,15,16,17,18} have presented some data on the risk of stroke from pre-existing atherosclerotic disease of the carotid arteries, they are limited because enrolment in the trials was delayed by 1 or more months after the TIA occurred. Small case series^19,20 have examined the relation between carotid artery disease and TIA, but without assessment of stroke outcome. Thus, the influence of atherosclerotic disease in the carotid artery on early stroke occurrence among people presenting with a TIA has not been assessed in any large study.²¹Using patients from the medical arm of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), we describe the early risk of stroke in a large number of patients with a TIA in whom internal carotid artery disease was the only presumed cause.