A contribution to the discussion on the safety of air weapons

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

Disruption of glycerol metabolism by RNAi targeting of genes encoding glycerol kinase results in a range of phenotype severity in Drosophila.

In Drosophila, RNAi targeting of either dGyk or dGK can result in two alternative phenotypes: adult glycerol hypersensitivity or larval lethality. Here we compare these two phenotypes at the level of glycerol kinase (GK) phosphorylation activity, dGyk and dGK-RNA expression, and glycerol levels. We found both phenotypes exhibit reduced but similar levels of GK phosphorylation activity. Reduced RNA expression levels of dGyk and dGK corresponded with RNAi progeny that developed into glycerol hypersensitive adult flies. However, quantification of dGyk/dGK expression levels for the larval lethality phenotype revealed unexpected levels possibly due to a compensatory mechanism between dGyk and dGK or RNAi inhibition. The enzymatic role of glycerol kinase converts glycerol to glycerol 3-phosphate. As expected, elevated glycerol levels were observed in larvae that went on to develop into glycerol hypersensitive adults. Interestingly, larvae that died before eclosion revealed extremely low glycerol levels. Further characterization identified a wing phenotype that is enhanced by a dGpdh null mutation, indicating disrupted glycerol metabolism underlies the wing phenotype. In humans, glycerol kinase deficiency (GKD) exhibits a wide range of phenotypic variation with no obvious genotype-phenotype correlations. Additionally, disease severity often does not correlate with GK phosphorylation activity. It is intriguing that both human GKD patients and our GKD Drosophila model show a range of phenotype severity. Additionally, the lack of correlation between GK phosphorylation and dGyk/dGK-RNA expression with phenotypic severity suggests further study including understanding the alternative functions of the GK protein, could provide insights into the complex pathogenic mechanism observed in human GKD patients

Factors affecting the sticking of insects on modified aircraft wings

Past studies have shown that the surface energy of a polymer coating has an important effect on the sticking of insects to the surface. However, mechanical properties of polymer coatings such as elasticity may also be important. A further study is suggested using polymer coatings of known surface energy and modulus so that a better understanding of the mechanism of the sticking of insects to surfaces can be achieved. As the first step for the study, surface analysis and road tests were performed using elastomers having different energies and different moduli. The number of insects sticking to each elastomer was counted and compared from sample to sample and with a control (aluminum). An average height moment was also calculated and comparisons made between samples

Factors affecting the sticking of insects on modified aircraft wings

Previous work showed that the total number of insects sticking to an aluminum surface was reduced by coating the aluminum surface with elastomers. Due to a large number of possible experimental errors, no correlation between the modulus of elasticity, the elastomer, and the total number of insects sticking to a given elastomer was obtained. One of the errors assumed to be introduced during the road test is a variable insect flux so the number of insects striking one surface might be different from that striking another sample. To eliminate this source of error, the road test used to collect insects was simulated in a laboratory by development of an insect impacting technique using a pipe and high pressure compressed air. The insects are accelerated by a compressed air gun to high velocities and are then impacted with a stationary target on which the sample is mounted. The velocity of an object exiting from the pipe was determined and further improvement of the technique was achieved to obtain a uniform air velocity distribution

One month of cocaine abstinence potentiates rapid dopamine signaling in the nucleus accumbens core

Cocaine addiction is a chronic relapsing disorder that is difficult to treat in part because addicts relapse even after extended periods of abstinence. Given the importance of the mesolimbic dopamine (DA) system in drug addiction, we sought to characterize cocaine abstinence induced changes in rapid DA signaling in the nucleus accumbens (NAc). Here, rats were trained to self-administer cocaine for 14 consecutive days, then divided into two groups. Day 1 rats (D1; n = 7) underwent 24 hours of abstinence; Day 30 rats (D30; n = 7) underwent one month of abstinence. After abstinence, all rats underwent a single extinction session. Immediately after, rats were deeply anesthetized and fast scan cyclic voltammetry (FSCV) was used to measure DA release and uptake dynamics in the NAc core before and following a single cocaine injection. We show that one month of cocaine abstinence potentiates the peak concentration of electrically evoked DA in the NAc core following an acute injection of cocaine. This potentiation is not related to alterations in DA uptake parameters, which are unchanged following abstinence, but may reflect alterations in release. These results further support the abundance of literature showing that cocaine abstinence induces neuroplasticity in brain areas implicated in drug reward and relapse. The present findings also demonstrate critical differences between abstinence-induced neuroadaptations in DA signaling and those caused by drug exposure itself

Continuity of symplectically adjoint maps and the algebraic structure of Hadamard vacuum representations for quantum fields on curved spacetime

We derive for a pair of operators on a symplectic space which are adjoints of each other with respect to the symplectic form (that is, they are sympletically adjoint) that, if they are bounded for some scalar product on the symplectic space dominating the symplectic form, then they are bounded with respect to a one-parametric family of scalar products canonically associated with the initially given one, among them being its ``purification''. As a typical example we consider a scalar field on a globally hyperbolic spacetime governed by the Klein-Gordon equation; the classical system is described by a symplectic space and the temporal evolution by symplectomorphisms (which are symplectically adjoint to their inverses). A natural scalar product is that inducing the classical energy norm, and an application of the above result yields that its ``purification'' induces on the one-particle space of the quantized system a topology which coincides with that given by the two-point functions of quasifree Hadamard states. These findings will be shown to lead to new results concerning the structure of the local (von Neumann) observable-algebras in representations of quasifree Hadamard states of the Klein-Gordon field in an arbitrary globally hyperbolic spacetime, such as local definiteness, local primarity and Haag-duality (and also split- and type III_1-properties). A brief review of this circle of notions, as well as of properties of Hadamard states, forms part of the article.Comment: 42 pages, LaTeX. The Def. 3.3 was incomplete and this has been corrected. Several misprints have been removed. All results and proofs remain unchange

Conformally invariant wave-equations and massless fields in de Sitter spacetime

Conformally invariant wave equations in de Sitter space, for scalar and vector fields, are introduced in the present paper. Solutions of their wave equations and the related two-point functions, in the ambient space notation, have been calculated. The ``Hilbert'' space structure and the field operator, in terms of coordinate independent de Sitter plane waves, have been defined. The construction of the paper is based on the analyticity in the complexified pseudo-Riemanian manifold, presented first by Bros et al.. Minkowskian limits of these functions are analyzed. The relation between the ambient space notation and the intrinsic coordinates is then studied in the final stage.Comment: 21 pages, LaTeX, some details adde

On the Localization of One-Photon States

Single photon states with arbitrarily fast asymptotic power-law fall-off of energy density and photodetection rate are explicitly constructed. This goes beyond the recently discovered tenth power-law of the Hellwarth-Nouchi photon which itself superseded the long-standing seventh power-law of the Amrein photon.Comment: 7 pages, tex, no figure

Relativistic Operator Description of Photon Polarization

We present an operator approach to the description of photon polarization, based on Wigner's concept of elementary relativistic systems. The theory of unitary representations of the Poincare group, and of parity, are exploited to construct spinlike operators acting on the polarization states of a photon at each fixed energy momentum. The nontrivial topological features of these representations relevant for massless particles, and the departures from the treatment of massive finite spin representations, are highlighted and addressed.Comment: Revtex 9 page

New concept of relativistic invariance in NC space-time: twisted Poincar\'e symmetry and its implications

We present a systematic framework for noncommutative (NC) QFT within the new concept of relativistic invariance based on the notion of twisted Poincar\'e symmetry (with all 10 generators), as proposed in ref. [7]. This allows to formulate and investigate all fundamental issues of relativistic QFT and offers a firm frame for the classification of particles according to the representation theory of the twisted Poincar\'e symmetry and as a result for the NC versions of CPT and spin-statistics theorems, among others, discussed earlier in the literature. As a further application of this new concept of relativism we prove the NC analog of Haag's theorem.Comment: 15 page