18,660 research outputs found

    Observed antiprotons and energy dependent confinement of cosmic rays: A conflict?

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    In the frame work of energy dependent confinement for cosmic rays, the energy spectrum inside the source is flatter than that observed. Antiproton observation suggests large amount of matter is being traversed by cosmic rays in some sources. As a result, secondary particles are produced in abundance. Their spectra was calculated and it is shown that the energy dependent confinement model is in conflict with some observations

    Supernova explosion in dense clouds in the galaxy and the COS-B gamma-ray sources

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    Supernova (SN) exploding in dense cloudlets produce large fluxes of gamma-rays. They would shine on gamma-ray sources, but their life time is small. Flux distribution of these sources in the Galaxy are calculated and compared with the COS-B catalogue of sources

    Spectral evolution of gamma-rays from adiabatically expanding sources in dense clouds

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    The excess of antiprotons (P) observed in cosmic ray was attributed to their production in supernova (SN) envelopes expanding in dense clouds. While creating P, gamma rays are also produced and these clouds would shine as gamma-ray sources. The evolution of the gamma-ray spectrum is calculated for clouds of r sub H = 10.000 and 100.000/cu cm

    Electrons and positrons from expanding supernova envelopes in dense clouds

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    If antiprotons in cosmic rays are produced as secondary particles in sources, it is expected that positrons are also created by the same process. The interstellar spectra of positrons and electrons are calculated by taking into account such sources. Spectra are then compared with observations

    Propagation of cosmic rays in the galaxy

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    The characteristics of a model for analyzing the propagation of cosmic rays are discussed. The requirements for analyzing the relevant observational data on cosmic rays are defines as: (1) the chemical and isotopic composition of cosmic rays as a function of energy, (2) the flux and energy spectrum of the individual nucleonic components, (3) the flux and energy spectrum of the electronic component, (4) the cosmic ray prehistory, and (5) the degree of isotropy in their arrival directions as a function of energy. It is stated that the model which has been able to bring to pass the greatest measure of success is the galactic confinement model

    Development of electromagnetic cascades in the atmosphere including the Landau-Pomeranchuk-Migdal effect

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    Numerical solutions have been obtained for the one-dimensional atmospheric electromagnetic cascade diffusion equations, including the Landau-Pomeranchuk-Migdal and screening effects. Spectra produced by primary gamma rays of various energies are given at a number of deths in the atmosphere

    Health and sustainable development

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    If sustainable development is to mean anything, people must be healthy enough to benefit from it and not have their lives cut off prematurely. Development without health is meaningless. But the processes which are likely to occur in a world undergoing globalisation, climate change, urbanisation, population increase and many other changes, will impact upon human health in complex ways. Some of them will benefit us, others will create new or augmented threats to survival and health, while many others will have a complex mixture of effects

    The real Living Wage in the London hospitality sector: opportunities and challenges

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    This report explores the opportunities and challenges of the implementation of the real Living Wage (rLW) in the hospitality sector in London, based on in-depth interviews with rLW-accredited hospitality employers and hospitality workers. Interviews with the hospitality employers show that there are clear opportunities that come with rLW adoption. It helps employers to position themselves as an ‘employer of choice’, thus improving their ability to recruit and retain good staff. Some see rLW adoption as a way to help improve the image of the industry. Even where employers already pay at London Living Wage levels they see value in seeking rLW accreditation, as it comes with various reputational benefits, including the ability to credibly portray themselves as a reputable employer and trusted brand. Challenges include the need to carefully consider the balance between service charges and a higher base pay, the maintenance of pay differentials, and the incorporation of the rLW in annual budget planning. Interviews with hospitality workers highlight financial and psychological benefits that those working in hospitality experience if they are paid a rLW as opposed to just a minimum wage. Findings also show that workers will only feel the full benefit of the rLW if they are offered sufficient and guaranteed hours; and if other aspects such as a good work environment, good additional benefits and development opportunities are available to them. Based on the insights gained from the research, this report proposes a number of recommendations to promote rLW adoption in the hospitality sector aimed at hospitality employers, industry bodies, the Living Wage Foundation, as well as policy makers and government

    Laboratory simulations of comet surfaces

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    The geometric albedos of frozen mixtures consisting of colloidal silica and carbon black mixed with water have been measured over the wavelength range of 400 to 800 nm to compare with recent observations of Comet Halley. Data were obtained as a function of sample temperature, scattering angle, and wavelength as the frozen samples warmed to 0 C in vacuum. Scattering from water ice, flat black paint, and Kodak white reflectance paint were also measured. Lab simulations show that the change in albedo of the samples show that sublimation of the water from the sample surface can have a major effect on the albedo of a particle/ice sample in the visible. Such processing may have a marked effect on the visible albedo of comet surfaces as well
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