Investigation into the impact of integral suppressor configurations on the pressure levels within the suppressor

This paper reports on an experimental investigation supported by basic modeling in to the performance of an integral suppressor on a low power firearm. A model was developed to determine the pressure within a suppressor chamber using iterative empirical calculations of the gas properties and flow within the system. The design of a reconfigurable suppressor chamber has been undertaken allowing suppressor chamber volume to be varied through the use of baffles. Pressure transducers were used to determine the pressure within the suppressor chamber for a series of firings. The results of the firings with different configurations within the suppressor are presented allowing trends to be established. The modeling and experimental results show an increase in suppressor chamber volume results in a reduction of recorded pressure within the suppressor chamber

Opportunities for weed manipulation using GMHT row crops

The herbicides and cultivation systems available in most non-GM crops allow farmers little flexibility as to when they control weeds. However, glyphosate and glufosinate-ammonium, as used in GM herbicide tolerant crops, offer the opportunity to control large weeds and weed control can be timed according to the agronomic and environmental aims of the user. This paper will use sugar beet as a model crop and report results where different approaches to weed control have been used and discuss their relevance in the wider agricultural and environmental contextNon peer reviewe

Comparison of porcine thorax to gelatine blocks for wound

Published online first in International Journal of Legal Medicine. The support of EPSRC and The Home Office are recognised. Open Access, this article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:/ /creativecommons.org/licenses/by/4.0/)Tissue simulants are typically used in ballistic testing as substitutes for biological tissues. Many simulants have been used, with gelatine amongst the most common. While two concentrations of gelatine (10 and 20 %) have been used extensively, no agreed standard exists for the preparation of either. Comparison of ballistic damage produced in both concentrations is lacking. The damage produced in gelatine is also questioned, with regards to what it would mean for specific areas of living tissue. The aim of the work discussed in this paper was to consider how damage caused by selected pistol and rifle ammunition varied in different simulants. Damage to gelatine blocks 10 and 20 % in concentration were tested with 9 mm Luger (9 × 19 full metal jacket; FMJ) rounds, while damage produced by .223 Remington (5.56 × 45 Federal Premium® Tactical® Bonded®) rounds to porcine thorax sections (skin, underlying tissue, ribs, lungs, ribs, underlying tissue, skin; backed by a block of 10 % gelatine) were compared to 10 and 20 % gelatine blocks. Results from the .223 Remington rifle round, which is one that typically expands on impact, revealed depths of penetration in the thorax arrangement were significantly different to 20 % gelatine, but not 10 % gelatine. The level of damage produced in the simulated thoraxes was smaller in scale to that witnessed in both gelatine concentrations,though greater debris was produced in the thoraxes.The support of EPSRC and The Home Office are recognised

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

PSR J1453+1902 and the radio luminosities of solitary versus binary millisecond pulsars

We present 3 yr of timing observations for PSR J1453+1902, a 5.79-ms pulsar discovered during a 430-MHz drift-scan survey with the Arecibo telescope. Our observations show that PSR J1453+1902 is solitary and has a proper motion of 8(2) mas/yr. At the nominal distance of 1.2 kpc estimated from the pulsar's dispersion measure, this corresponds to a transverse speed of 46(11) km/s, typical of the millisecond pulsar population. We analyse the current sample of 55 millisecond pulsars in the Galactic disk and revisit the question of whether the luminosities of isolated millisecond pulsars are different from their binary counterparts. We demonstrate that the apparent differences in the luminosity distributions seen in samples selected from 430-MHz surveys can be explained by small-number statistics and observational selection biases. An examination of the sample from 1400-MHz surveys shows no differences in the distributions. The simplest conclusion from the current data is that the spin, kinematic, spatial and luminosity distributions of isolated and binary millisecond pulsars are consistent with a single homogeneous population.Comment: 8 pages, 5 figures and 3 tables, accepted for publication by MNRA

Comparison of physiological and perceptual responses to a maximal exhaustive test performed on the SRM and the Cyclus2 ergometer

Background: No cycle ergometer perfectly replicates the physiological demands and movement patterns associated with real world cycling (Abbiss et al., 2009: International Journal of Sports Medicine, 30(2), 107-112). The purpose of this research was to compare physiological and perceptual responses during a standardized exercise test using the classical SRM ergometer (Schoberer Rad Messtechnik, GmbH, Jülich, Germany) and the Cyclus2 ergometer (RBM elektronik-automation GmbH, Leipzig, Germany) which allows the use of personal bikes and allows lateral movement. Methods: 13 moderately trained cyclists (mean ± SD: age 35 ± 7 years, body mass 74.1 ± 9.6 kg) performed two graded cycling tests to volitional exhaustion in a randomized order on the SRM and the Cyclus2 ergometer. Maximal aerobic capacity (VO2max), maximal aerobic power (MAP), blood lactate concentrations and heart rate responses were compared using a paired t-test. Participants were also required to fill in the NASA Task Load Index (TLX) questionnaire (Hart, 2006: NASA-Task Load Index, 50th Human Factors and Ergonomics Society Meeting, Santa Monica, USA) after each test to assess the perceived workload in an effort to understand if one ergometer is perceived to be more or less of a workload than its counterpart. In order to analyse the workload from each participant, individual TXL factors were summed for each ergometer TLX administration creating an overall workload score per ergometer. After conclusion of the experiment participants were asked to state their preference in ergometers. Lastly, a correlation was performed on the level of performance within the ergometer testing and the perceived performance. Results: Compared physiological responses and MAP (321 ± 44 W; SRM and 326 ± 41 W; Cyclus2) did not find any significant differences. A constructed ANOVA model which examined the difference of the overall workload scores between the two ergometers did not show any significant difference (F(1,12) = .025, p = .876). In order to examine if there were individual factor differences between the six TLX factors of each ergometer, a constructed repeated measure MANOVA did not reveal any significant differences between ergometers and within individual TLX scores (F(5,8) = .995, p = .477). Interestingly, the absolute VO2max performance score was significantly correlated on the Cyclus2 ergometer with the self-reported performance TLX factor (r = .560, p = .047) while the same score was not significant for the SRM ergometer (r = .247, p = .415). However, participants were highly positively correlated between perceived performance on each ergometer (r = .736, p = .004). Participants were asked to name which ergometer they felt they performed better on. Eight participants named the SRM Ergometer, while 5 named the Cyclus2. When asked which ergometer they preferred to use, 4 named the SRM Ergometer, while 9 named the Cyclus2. When asked which ergometer the participant would prefer to use if the test were to be run again, 5 named the SRM Ergometer, while 8 named the Cyclus2. Participants were lastly asked to think of how comfortable they were for each of the ergometers. A paired t-test examined the differences between the comfort ratings of revealed a significant difference (t = -2.803, p = .016), with this being driven by the higher favourable ratings of the Cyclus2 compared to the SRM (Figure 1). These differences can be accounted for by 6 participants stating that they preferred the Cyclus2 and increased comfort owning to the usage of their own bike. Those that preferred the SRM stated it was more solid and stable (n = 4). Discussion: Biomechanical factors can influence physiological responses, perception of exercise and efficiency of an individual riding a bicycle or ergometer at a given power output (Patterson and Moreno, 1990: Medicine & Science in Sports & Exercise, 22(4), 512-516. Whilst not demonstrating any differences in physiological variables and MAP, participants generally felt more comfortable on the ergometer, which allows the use of personal bikes and which appears to replicate real world cycling more closel

An investigation of pulsar searching techniques with the Fast Folding Algorithm

Here we present an in-depth study of the behaviour of the Fast Folding Algorithm, an alternative pulsar searching technique to the Fast Fourier Transform. Weaknesses in the Fast Fourier Transform, including a susceptibility to red noise, leave it insensitive to pulsars with long rotational periods (P > 1 s). This sensitivity gap has the potential to bias our understanding of the period distribution of the pulsar population. The Fast Folding Algorithm, a time-domain based pulsar searching technique, has the potential to overcome some of these biases. Modern distributed-computing frameworks now allow for the application of this algorithm to all-sky blind pulsar surveys for the first time. However, many aspects of the behaviour of this search technique remain poorly understood, including its responsiveness to variations in pulse shape and the presence of red noise. Using a custom CPU-based implementation of the Fast Folding Algorithm, ffancy, we have conducted an in-depth study into the behaviour of the Fast Folding Algorithm in both an ideal, white noise regime as well as a trial on observational data from the HTRU-S Low Latitude pulsar survey, including a comparison to the behaviour of the Fast Fourier Transform. We are able to both confirm and expand upon earlier studies that demonstrate the ability of the Fast Folding Algorithm to outperform the Fast Fourier Transform under ideal white noise conditions, and demonstrate a significant improvement in sensitivity to long-period pulsars in real observational data through the use of the Fast Folding Algorithm.Comment: 19 pages, 15 figures, 3 table

New Binary and Millisecond Pulsars from Arecibo Drift-Scan Searches

We discuss four recycled pulsars found in Arecibo drift-scan searches. PSR J1944+0907 has a spin period of 5.2 ms and is isolated. The 5.8-ms pulsar J1453+19 may have a low-mass companion. We discuss these pulsars in the context of isolated millisecond pulsar formation and the minimum spin period of neutron stars. The isolated 56-ms pulsar J0609+2130 is possibly the remnant of a disrupted double neutron star binary. The 41-ms pulsar J1829+2456 is in a relativistic orbit. Its companion is most likely another neutron star, making this the eighth known double neutron star binary system.Comment: 6 pages, 3 figures, to appear in proceedings of Aspen Center for Physics Conference on ``Binary Radio Pulsars'' Eds. F. Rasio and I. Stair

The JKind Model Checker

JKind is an open-source industrial model checker developed by Rockwell Collins and the University of Minnesota. JKind uses multiple parallel engines to prove or falsify safety properties of infinite state models. It is portable, easy to install, performance competitive with other state-of-the-art model checkers, and has features designed to improve the results presented to users: inductive validity cores for proofs and counterexample smoothing for test-case generation. It serves as the back-end for various industrial applications.Comment: CAV 201