Wounding patterns and human performance in knife attacks: optimising the protection provided by knife-resistant body armour

Stab attacks generate high loads,1 and to defeat them, armour needs to be of a certain thickness and stiffness.2,3 Slash attacks produce much lower loads and armour designed to defeat them can be far lighter and more flexible.Methods and subjects: Phase 1: Human performance in slash attacks: 87 randomly selected students at the Royal Military College of Science were asked to make one slash attack with an instrumented blade on a vertically mounted target. No instructions on how to slash the target were given. The direction, contact forces and velocity of each attack were recorded. Phase 2: Clinical experience with edged weapon attacks: The location and severity of all penetrating injuries in patients attending the Glasgow Royal Infirmary between 1993 and 1996 were charted on anatomical figures.Results Phase 1: Two types of human slash behaviour were evident: a ‘chop and drag’ blow and a ‘sweep motion’ type of attack. ‘Chop and drag’ attacks had higher peak forces and velocities than sweep attacks. Shoulder to waist blows (diagonal) accounted for 82% of attacks, 71% of attackers used a long diagonal slash with an average cut length of 34 cm and 11% used short diagonal attacks with an average cut length of 25 cm. Only 18% of attackers slashed across the body (short horizontal); the average measured cut length of this type was 28 cm. The maximum peak force for the total sample population was 212 N; the maximum velocity was 14.88 m s−1. The 95 percentile force for the total sample population was 181 N and the velocity was 9.89 m s−1. Phase 2: 431 of the 500 patients had been wounded with edged weapons. The average number of wounds sustained by victims in knife assaults was 2.4. The distribution of wounds by frequency and severity are presented.Conclusions Anti-slash protection is required for the arms, neck, shoulders, and thighs. The clinical experience of knife-attack victims provides information on the relative vulnerabilities of different regions of the body. It is anticipated that designing a tunic-type of Police uniform that is inherently stab and slash resistant will eventually replace the current obvious and often bulky extra protective vest. Attempts at making a combined garment will need to be guided by ergonomic considerations and field testing. A similar anatomical regional risk model might also be appropriate in the design of anti-ballistic armour and combined anti-ballistic and knife-resistant armour

Impact perforation testing of stab-resistant armour materials

This paper describes the development of a method for the investigation and comparison of materials for use in stab resistant body armour. A number of polymer composite panels of different thicknesses and construction have been tested. A dynamic test which simulated the real threat has been used and the results compared to a simpler quasi-static test that might be used in initial materials selection. The materials tested were glass-epoxy, and glass-nylon composite panels of several thicknesses between 1.8 and 5.8mm. Additional tests were also performed on similar composites containing tungsten wires. An accelerated instrumented drop-tower was used to drive a knife through composite panels and record the force resisting penetration by the knife. The final penetration of the knife through the armour into a soft backing was also measured. For comparison,a similar geometry quasi-static test was carried out on the same specimens. It was found that energy absorbtion took the form of an initial resistance to perforation and then by a resistance to further penetration. This is thought to stem from resistance to cutting ofthe panel material and gripping of the knife blade. The energy required to produce a given penetration in dynamic tests was found to be in good agreement with the penetration achieved at similar energies under quasi-static conditions. For the materials tested there was no significant difference between the penetration resistance of single or two layer systems. The penetration achieved through a panel of a given material was approximately proportional to the inverse square of the panel's thickness. The relative performance of different armour materials was assessed by plotting the energy required to penetrate a fixed distance against the areal density of the panel

The study of a human head simulant's dynamic response to a blast wave

The prevalence of body armour and helmets in military forces combined with the availability of combat medical support and timely evacuation of injured soldiers has increased the survivability rates of those who have been exposed to blast. Despite this, the incidents of traumatic brain injury (TBI), as a result of primary blast, have been described as the 'ignature injury' of modern warfare. The physical interaction between a blast wave and a human head is not well understood and there is some conjecture as to whether helmets are attenuating or amplifying the blast effects on the human head. The aim of this study was to improve the understanding of the interaction of primary blasts on the human head with different attachments such as a helmet and face shield

Prediagnostic presentations of Parkinson's disease in primary care: a case-control study

Background: Parkinson’s disease (PD) has an insidious onset and is diagnosed when typical motor features occur. A number of motor and non-motor features may occur during a “pre-diagnostic” phase, reflecting the early disease process. Previously there has been no comprehensive analysis in the general population of the relative magnitude and timing of their association with PD diagnosis. Aim: To assess the association of first presentation of several pre-diagnostic features in primary care with a subsequent diagnosis of PD, and to chart the timeline of these first presentations before diagnosis of PD. Methods: 8,166 individuals with a first diagnosis of PD and 46,755 individuals without PD were identified from 1st January 1996 to 31st December 2012 from The Health Improvement Network, United Kingdom primary care database. Codes were extracted for a wide range of possible pre-diagnostic or early symptoms comprising motor features (tremor, rigidity, balance impairment, neck pain and shoulder pain), autonomic features (constipation, hypotension, dizziness, erectile dysfunction, urinary dysfunction), mental disturbances (memory problems, depression, anxiety) and additional features (fatigue, insomnia) in the years prior to diagnosis. Incidence rates for symptoms recorded in more than 1% of cases per 1000 person years and incidence risk ratio (RR) were calculated and compared for individuals with and without PD at two, five and ten years before diagnosis. Findings: At two years before PD diagnosis the incidence of all examined pre-diagnostic features except neck pain was higher in patients (n=7,232) than in controls (n=40,541). At five years before diagnosis, patients with PD (n=4,769) had higher incidence rates of tremor (RR 13.70 (95%CI 7.82-24.31), balance impairment (RR, 2.19 (95%CI 1.09-4.16), depression (RR 1.76 (95%CI 1.41-2.17), anxiety (RR 1.41 (95%CI 1.09-1.79), constipation (RR 2.24 (95%CI 2.04-2.46), postural hypotension (RR 3.23 (95%CI 1.85-5.52), dizziness (RR 1.99 (95%CI 1.67-2.37), erectile dysfunction (RR 1.30 (95%CI 1.11-1.51), fatigue (RR 1.56 (95%CI 1.27-1.91), and urinary dysfunction (RR 1.96 (95%CI 1.34-2.80) than controls (n=25,544). At ten years before diagnosis of PD the incidence of constipation (RR 2.01 (95%CI 1.62-2.49) and tremor (RR 7.59 (95%CI 1.1-44.8) was already higher in those with later diagnosis with PD (n=1,680) than in controls (n=8,305). Interpretation: This study for the first time provides evidence for a range of pre-diagnostic features that can be detected several years before diagnosis of PD in primary care, estimating the comparative magnitude of risk for each and where they fit in the prodromal timeline. These data on the pre-diagnostic symptoms of PD can be incorporated into ongoing efforts to identify individuals at the earliest stages of the disease in future trials and help understand progression in the earliest phase of PD

Teacher perspectives of cultivating learning through practitioner enquiry to transform practice

This paper reports on the first year of an innovative Postgraduate Certificate (PGCert) in Advanced Education Practice, designed to meet the specific staff and development needs of one school in the North West of England. The programme is underpinned by three strands of practice based learning: learning about practice (theory), learning in practice (application) and learning through practice (reflection) through critical reflection. This paper considers professional development situated around teaching and learning and outlines a new approach to cultivating learning, both for teachers and educational practitioners through a collaborative learning model with a Higher Education Institute (HEI). A further strand to the research considers transformative impact on practice including references to personal experience and reflections by the participants. Throughout the report it is evident that school leaders were keen to enhance the performance of staff by supporting them in Masters level study to enhance professional practice and impact on learning. Through questionnaires and interviews, an insight into personal and professional impact, challenges, evaluation, details of the progression, next steps in the small scale research study were considered

Comparison of Two Detailed Models of Aedes aegypti Population Dynamics

The success of control programs for mosquito-­borne diseases can be enhanced by crucial information provided by models of the mosquito populations. Models, however, can differ in their structure, complexity, and biological assumptions, and these differences impact their predictions. Unfortunately, it is typically difficult to determine why two complex models make different predictions because we lack structured side-­by-­side comparisons of models using comparable parameterization. Here, we present a detailed comparison of two complex, spatially explicit, stochastic models of the population dynamics of Aedes aegypti, the main vector of dengue, yellow fever, chikungunya, and Zika viruses. Both models describe the mosquito?s biological and ecological characteristics, but differ in complexity and specific assumptions. We compare the predictions of these models in two selected climatic settings: a tropical and weakly seasonal climate in Iquitos, Peru, and a temperate and strongly seasonal climate in Buenos Aires, Argentina. Both models were calibrated to operate at identical average densities in unperturbedconditions in both settings, by adjusting parameters regulating densities in each model (number of larval development sites and amount of nutritional resources). We show that the models differ in their sensitivityto environmental conditions (temperature and rainfall) and trace differences to specific model assumptions.Temporal dynamics of the Ae. aegypti populations predicted by the two models differ more markedly under strongly seasonal Buenos Aires conditions. We use both models to simulate killing of larvae and/or adults with insecticides in selected areas. We show that predictions of population recovery by the models differ substantially, an effect likely related to model assumptions regarding larval development and (director delayed) density dependence. Our methodical comparison provides important guidance for model improvement by identifying key areas of Ae. aegypti ecology that substantially affect model predictions, and revealing the impact of model assumptions on population dynamics predictions in unperturbed and perturbed conditions.Fil: Legros, Mathieu. University of North Carolina; Estados UnidosFil: Otero, Marcelo Javier. Universidad de Buenos Aires; ArgentinaFil: Romeo Aznar, Victoria Teresa. Universidad de Buenos Aires; ArgentinaFil: Solari, Hernan Gustavo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Gould, Fred. National Institutes of Health; Estados UnidosFil: Lloyd, Alun L.. National Institutes of Health; Estados Unido

Movement side effects of antipsychotic drugs in adults with and without intellectual disability: UK population-based cohort study

OBJECTIVES: To measure the incidence of movement side effects of antipsychotic drugs in adults with intellectual disability and compare rates with adults without intellectual disability. DESIGN: Cohort study using data from The Health Improvement Network. SETTING: UK primary care. PARTICIPANTS: Adults with intellectual disability prescribed antipsychotic drugs matched to a control group of adults without intellectual disability prescribed antipsychotic drugs. OUTCOME MEASURES: New records of movement side effect including acute dystonias, akathisia, parkinsonism, tardive dyskinaesia and neuroleptic malignant syndrome. RESULTS: 9013 adults with intellectual disability and a control cohort of 34 242 adults without intellectual disability together contributed 148 709 person-years data. The overall incidence of recorded movement side effects was 275 per 10 000 person-years (95% CI 256 to 296) in the intellectual disability group and 248 per 10 000 person-years (95% CI 237 to 260) in the control group. The incidence of any recorded movement side effect was significantly greater in people with intellectual disability compared with those without (incidence rate ratio 1.30, 95% CI 1.18 to 1.42, p<0.001, after adjustment for potential confounders), with parkinsonism and akathisia showing the greatest difference between the groups. Neuroleptic malignant syndrome, although occurring infrequently, was three times more common in people with intellectual disability-prescribed antipsychotic drugs (incidence rate ratio 3.03, 95% CI 1.26 to 7.30, p=0.013). Differences in rates of movement side effects between the groups were not due to differences in the proportions prescribed first and second-generation antipsychotic drugs. CONCLUSIONS: This study provides evidence to substantiate the long-held assumption that people with intellectual disability are more susceptible to movement side effects of antipsychotic drugs. Assessment for movement side effects should be integral to antipsychotic drug monitoring in people with intellectual disability. Regular medication review is essential to ensure optimal prescribing in this group