5,064 research outputs found

    A contribution to the discussion on the safety of air weapons

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    Firearms legislation in the UK stems from the Firearms Act 1968 with its definition of a firearm as a lethal barrelled weapon of any description. The Act allows certain exceptions to be held without licence, most notably air weapons although these are limited by The Firearms (Dangerous Air Weapons) Rules 1969 and related regulations to below 12 ft lb (16.3 J) for air rifles and below 6 ft lb (8.1 J) for air pistols. Despite this there are occasional fatalities, typically 1 or 2 each year in the UK, from legally owned air weapons. In the USA there are over 20,000 visits each year to emergency departments due to injuries from air weapons and paintball guns. Despite this, limited research appears to have been carried out into the safety of air weapons and the present study tries to address this.Fresh samples of animal tissue were obtained from an abattoir or butcher and were embedded in ballistic gelatin. Pig heart, lung, liver and shoulder were used. By firing pellets into gelatin alone and into the combination of the gelatin and animal tissue it was possible to compare gelatin as a model for these tissues. The depth of penetration was similar but the residual track appeared to remain more open in the animal tissue. Pellets penetrated completely through the organ, with total penetration of gelatin and organ being typically around 10–15 cm.Samples of pig, cow and chicken skin were placed in contact with the gelatin or embedded in the gelatin to simulate the effect of skin on penetration into a body. Chicken skin had no effect, pig skin stopped the pellet and cow skin was perforated by the pellet. If cow skin was embedded in the gelatin there was little effect on the total amount of penetration, but cow skin on the front surface of the gelatin reduced penetration by about 30%.Computed tomography was used to examine the pellet track and to calculate the volume of damage produced. However, due to the similar densities of gelatin and organ a technique had to be developed to differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue.Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited.Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limit which could be proposed as safe

    Sabbatical Leave Proposal

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    I intend to study those aspects of planetarium education of which, at the time of the sabbatical, the college most urgently needs an understanding. I intend to do whatever is necessary to enable the Parkland Planetarium to commence successful operations in 1987. I also wish to attend meetings of those professional planetarium societies in which I hold membership, Β·and to participate in two planetarium education workshops

    Double coset enumeration

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    AbstractCoset enumeration is the principal method for solving the word problem in finitely presented groups. The technique has a long history and was one of the first applications of electronic computers to pure mathematics. Present applications are limited by the space available to store the coset table in computer memory. Enumerating double cosets offers a substantial saving of space in suitable cases. An algorithm is described with some notes on implementation

    Inactive alleles of cytochrome P450 2C19 may be positively selected in human evolution Genome evolution and evolutionary systems biology

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    Β© 2014 Janha et al.; licensee BioMed Central Ltd.Background: Cytochrome P450 CYP2C19 metabolizes a wide range of pharmacologically active substances and a relatively small number of naturally occurring environmental toxins. Poor activity alleles of CYP2C19 are very frequent worldwide, particularly in Asia, raising the possibility that reduced metabolism could be advantageous in some circumstances. The evolutionary selective forces acting on this gene have not previously been investigated. We analyzed CYP2C19 genetic markers from 127 Gambians and on 120 chromosomes from Yoruba, Europeans and Asians (Japanese + Han Chinese) in the Hapmap database. Haplotype breakdown was explored using bifurcation plots and relative extended haplotype homozygosity (REHH). Allele frequency differentiation across populations was estimated using the fixation index (FST) and haplotype diversity with coalescent models. Results: Bifurcation plots suggested conservation of alleles conferring slow metabolism (CYP2C19βˆ—2 and βˆ—3). REHH was high around CYP2C19βˆ—2 in Yoruba (REHH 8.3, at 133.3 kb from the core) and to a lesser extent in Europeans (3.5, at 37.7 kb) and Asians (2.8, at -29.7 kb). FST at the CYP2C19 locus was low overall (0.098). CYP2C19βˆ—3 was an FST outlier in Asians (0.293), CYP2C19 haplotype diversity ST is low at the CYP2C19 locus, suggesting balancing selection overall. The biological factors responsible for these selective pressures are currently unknown. One possible explanation is that early humans were exposed to a ubiquitous novel toxin activated by CYP2C19. The genetic adaptation took place within the last 10,000 years which coincides with the development of systematic agricultural practices.This work was supported by the Medical Research Council Unit The Gambia and the European and Developing Countries Clinical Trials Partnership [grant number CG_ta_05_40204_018]
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