Chirped and modulated electron pulse free electron laser techniques

A potential method to improve the free electron laser’s output when the electron pulse has a large energy spread is investigate and results presented. A simplified model is the first given, in which there are a number of linearly chirped beamlets equally separated in energy and time. By using chicanes, radiation from one chirped beamlet is passed to the next, helping to negate the effect of the beamlet chirps and maintaining resonant interactions. Hence the addition of chicane allow the electrons to interact with a smaller range of frequencies (Δω<2ργr), sustaining the FEL interaction. One method to generate such a beamlet structure is presented and is shown to increase FEL performance by two orders of magnitude

Generation of variable polarisation in a short wavelength FEL amplifier

So far, short wave­length Free Elec­tron Laser am­pli­fiers have pro­duced lin­ear­ly po­larised ra­di­a­tion. For sev­er­al im­por­tant class­es of ex­per­i­ment, vari­able po­lar­i­sa­tion is re­quired. For ex­am­ple, in the wave­length range from 1.5 to 2.5 nm, light po­lar­i­sa­tion is im­por­tant in char­ac­ter­is­ing mag­net­ic ma­te­ri­als where mea­sure­ments de­pend crit­i­cal­ly upon the hand­ed­ness of the po­lar­i­sa­tion. It is there­fore im­por­tant that the po­lar­i­sa­tion does not fluc­tu­ate be­tween mea­sure­ments. In this paper, we study pos­si­ble meth­ods to gen­er­ate vari­ably po­larised light and con­sid­er its shot-to-shot sta­bil­i­ty

Socio-demographic characteristics, lifestyle factors and burden of morbidity associated with self-reported hearing and vision impairments in older British community-dwelling men: a cross-sectional study.

BACKGROUND: Hearing and vision problems are common in older adults. We investigated the association of self-reported sensory impairment with lifestyle factors, chronic conditions, physical functioning, quality of life and social interaction. METHODS: A population-based cross-sectional study of participants of the British Regional Heart Study aged 63-85 years. RESULTS: A total of 3981 men (82% response rate) provided data. Twenty-seven per cent (n = 1074) reported hearing impairment including being able to hear with aid (n = 482), being unable to hear (no aid) (n = 424) and being unable to hear despite aid (n = 168). Three per cent (n = 124) reported vision impairment. Not being able to hear, irrespective of use of hearing aid, was associated with poor quality of life, poor social interaction and poor physical functioning. Men who could not hear despite hearing aid were more likely to report coronary heart disease (CHD) [age-adjusted odds ratios (ORs) 1.89 (95% confidence interval 1.36-2.63)]. Vision impairment was associated with symptoms of CHD including breathlessness [OR 2.06 (1.38-3.06)] and chest pain [OR 1.58 (1.07-2.35)]. Vision impairment was also associated with poor quality of life, poor social interaction and poor physical functioning. CONCLUSIONS: Sensory impairment is associated with poor physical functioning, poor health and poor social interaction in older men. Further research is warranted on pathways underlying these associations

Up-sampling of electron beam simulation particles with addition of shot-noise

An algorithm and numerical code for the up-sampling of a system of particles, from a smaller to a larger number, is described. The method introduces a Poissonian `shot-noise' to the up-sampled distribution, typical of the noise statistics arising in a bunch of particles generated by a particle accelerator. The algorithm is applied to a 6-Dimensional phase-space distribution of relatively few simulation particles, representing an electron beam generated by particle accelerator modelling software, for subsequent injection into an Free Electron Laser (FEL) amplifier which is used here to describe the model. A much larger number of particles is usually required to model the FEL lasing process than is required to model the electron beam accelerators that drive it. FEL modelling software usually requires a much greater number of simulation particles than is required for modelling the acceleration stages and an increase in simulation particles is required while introducing the correct Poisson statistical properties of a real electron distribution. A numerical code developed from the algorithm was then used to generate electron bunches for injection into to an unaveraged 3D FEL simulation code, Puffin. Results show good qualitative and quantitative agreement with analytical theory. The program and user manual is available for download

Additive manufacturing of alumide jewellery

Additive Manufacturing (AM) has been used for various jewellery applications in the recent past - both through direct and indirect use of AM products. The typical trend for direct manufactured jewellery has however, been dominated by metals-based applications. Materialise, through their MGX collection, has helped to set a new trend of doing functional design / functional art through amongst others, direct laser sintered polymers. They have created a significant demand for direct manufactured products that are not possible to manufacture with conventional technologies. More importantly, some of these designs enable an element of personalisation, to lead to "bespoke art". Within a collaborative research project between De Montfort University (UK), Loughborough University (UK) and Vaal University of Technology (SA), one of the specific research outcomes was aimed at producing designs for direct AM jewellery in AlumideTM, an Aluminum and Nylon matrix. The objective was to go beyond complex shapes, to also create innovative techniques for insertion of gemstones in these designs, to result in limited production of "bespoke jewellery series". The paper and associated presentation will report on work in progress from the collaborative project, and will discuss first results, problem areas and future possibilities

Cutting cardiovascular risk in barbershops

http://dx.doi.org/10.1016/j.jomh.2009.07.00

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

Influence of Dietary Oil Content and Conjugated Linoleic Acid (CLA) on Lipid Metabolism Enzyme Activities and Gene Expression in Tissues of Atlantic Salmon (Salmo salar L.)

The overall objective is to test the hypothesis that conjugated linoleic acid (CLA) has beneficial effects in Atlantic salmon through affecting lipid and fatty acid metabolism. The specific aims of the present study were to determine the effects of CLA on some key pathways of fatty acid metabolism including fatty acid oxidation and highly unsaturated fatty acid (HUFA) synthesis. Salmon smolts were fed diets containing two levels of fish oil (low, ~18% and high, ~34%) containing three levels of CLA (a 1:1 mixture of 9-cis,trans-11 and trans-10,cis-12 at 0, 1 and 2% of diet) for 3 months. The effects of dietary CLA on HUFA synthesis and β-oxidation were measured and the expression of key genes in the fatty acid oxidation and HUFA synthesis pathways, and potentially important transcription factors, peroxisome proliferators activated receptors (PPARs), determined in selected tissues. Liver HUFA synthesis and desaturase gene expression was increased by dietary CLA and decreased by high dietary oil content. Carnitine palmitoyltransferase-I (CPT-I) activity and gene expression were generally increased by CLA in muscle tissues although dietary oil content had relatively little effect. In general CPT-I activity or gene expression was not correlated with β-oxidation. Dietary CLA tended to increase PPARα and β gene expression in both liver and muscle tissues, and PPARγ in liver. In summary, gene expression and activity of the fatty acid pathways were altered in response to dietary CLA and/or oil content, with data suggesting that PPARs are also regulated in response to CLA. Correlations were observed between dietary CLA, liver HUFA synthesis and desaturase gene expression, and liver PPARα expression, and also between dietary CLA, CPT-I expression and activity, and PPARα expression in muscle tissues. In conclusion, this study suggests that dietary CLA has effects on fatty acid metabolism in Atlantic salmon and on PPAR transcription factors. However, further work is required to assess the potential of CLA as a dietary supplement, and the role of PPARs in the regulation of lipid metabolism in fish

The semiology of changing brand image

This article considers the attempted change to the image of an established brand by studying the semiotics within the brand’s historical advertising campaigns. The use of semiotics to study the interpretation of messages is discussed, and the link between interpretation of messages and advertising effectiveness in changing brand image is explored. The authors deconstruct advertisements of a brand to provide a model containing opposing dialectics that may aid managers by highlighting alternative symbolic messages contained in advertisements. Oncwe identified, these alternative symbolic messages may be used to help change brand image and influence advertising effectiveness. Although the study focuses upon a major brand of beer, this is an industry in which there are numerous small firms, and many of those have constrained marketing budgets, and thus need to make sure that their advertising is effective. Equally, entrepreneurial marketing is not to found only in the small firm, and the case study discusses a radical and imaginative brand repositioning of a well established product