The impulsive phase of solar flares. 2: Characteristics of the hard X-rays

The results of an investigation into the electron distribution in the general non-thermal models of solar flares were used to calculate the characteristics of the impulsive hard X-rays. The height distribution, the spectrum, the polarization, and directivity of the X-rays were observed and how these X-ray characteristics are affected by the parameters defining the model was investigated. An expression is obtained for the X-ray intensity as a function of source height which is an excellent fit under certain constraints. Some available data with spatial resolution are examined and it is shown that it is possible to reproduce these data adequately with the non-thermal model and to determine the values of the parameters describing the flares

Correlation of hard X-ray and type 3 bursts in solar flares

Correlations between X-ray and type 3 radio emission of solar bursts are described through a bivariate distribution function. Procedures for determining the form of this distribution are described. A model is constructed to explain the correlation between the X-ray spectral index and the ratio of X-ray to radio intensities. Implications of the model are discussed

A polyphonic acoustic vortex and its complementary chords

Using an annular phased array of eight loudspeakers, we generate sound beams that simultaneously contain phase singularities at a number of different frequencies. These frequencies correspond to different musical notes and the singularities can be set to overlap along the beam axis, creating a polyphonic acoustic vortex. Perturbing the drive amplitudes of the speakers means that the singularities no longer overlap, each note being nulled at a slightly different lateral position, where the volume of the other notes is now nonzero. The remaining notes form a tri-note chord. We contrast this acoustic phenomenon to the optical case where the perturbation of a white light vortex leads to a spectral spatial distribution

The interpretation of hard X-ray polarization measurements in solar flares

Observations of polarization of moderately hard X-rays in solar flares are reviewed and compared with the predictions of recent detailed modeling of hard X-ray bremsstrahlung production by non-thermal electrons. The recent advances in the complexity of the modeling lead to substantially lower predicted polarizations than in earlier models and more fully highlight how various parameters play a role in determining the polarization of the radiation field. The new predicted polarizations are comparable to those predicted by thermal modeling of solar flare hard X-ray production, and both are in agreement with the observations. In the light of these results, new polarization observations with current generation instruments are proposed which could be used to discriminate between non-thermal and thermal models of hard X-ray production in solar flares

Future energy transitions for bagasse cogeneration: Lessons from multi-level and policy innovations in Mauritius

Agro-industries have the potential to catalyse energy access and promote development. Mauritius is one of the most advanced countries in the use of waste from sugar processing (bagasse) to simultaneously generate heat and electricity (cogeneration) to feed into the grid, but developments have evolved over several decades with complex dynamics between different actors. A multi-level perspective is used in this paper to examine this process and to extract policy lessons for other countries. The analysis shows how policies influenced the development of the bagasse cogeneration niche and changes in the sugar and energy regimes over time. The formation of independent power producers, centralisation of sugar mills, the use of a complementary fuel (coal) in the off-crop season, and targeted financial incentives were important for the development of bagasse cogeneration in Mauritius. Mauritian sugar mills are at the forefront of niche technological and organisational innovations in response to recent reduction in sugar prices. The country has been able to respond to changes and manage niche innovations strategically due to the deployment of finance, technical expertise and strong governance structures which enabled the government to coordinate with industry. Therefore, local capacity and institutional context are important for managing transitions towards sustainable energy

Analytic Behaviour of Competition among Three Species

We analyse the classical model of competition between three species studied by May and Leonard ({\it SIAM J Appl Math} \textbf{29} (1975) 243-256) with the approaches of singularity analysis and symmetry analysis to identify values of the parameters for which the system is integrable. We observe some striking relations between critical values arising from the approach of dynamical systems and the singularity and symmetry analyses.Comment: 14 pages, to appear in Journal of Nonlinear Mathematical Physic

Nodular lymphocyte predominant Hodgkin lymphoma behaves as a distinct clinical entity with good outcome: evidence from 14-year followup in the West of Scotland Cancer Network

Clinically and biologically, nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) has much more in common with germinal-center derived B-cell non-Hodgkin lymphoma (NHL) than with classical Hodgkin lymphoma (cHL). Management of NLPHL remains controversial. In a 14-year multicenter series, 69 cases were analyzed, and the median follow-up was 53 months (range 11–165.) B-symptoms were present in only 4.3% of patients, and 81.1% of patients had stage I/II disease. Treatment was with radiotherapy (53.6%), chemotherapy (21.7%), combined modality (17.4%), and observation (7.2%). In all, 10.1% of patients relapsed and 2.9% of patients developed high-grade transformation to DLBCL. All relapses and transformations were salvageable. No patient died of their disease. The 5-year relapse-free survival was 92%, transformation-free survival 98.4%, and overall survival 100%. We conclude that NLPHL behaves as a distinct clinical entity, often presenting at an early stage without risk factors. It has an excellent outcome. It may be possible, in early-stage disease, to reduce the intensity of therapy in NLPHL, to single-modality radiotherapy, without affecting OS

Ocular structure in vitamin A deficiency in the monkey

1. The role of vitamin A in the metabolism of cone cells of the retina was investigated, from the morphological angle, by studying their structure in induced deficiency of vitamin A in three monkeys. 2. Unequivocal signs of structural damage were observed in the cone and rod cells of the deficient animals, which also showed the classical signs of vitamin A deficiency in other organs. 3. In vitamin A deficiency, damage to the visual cell layer of the retina occurred in one monkey in the absence of corneal involvement. This finding suggests that chronic vitamin A deficiency in the community may lead to progressive damage to the visual cells in a much larger number of persons than the incidence figures for keratomalacia indicate. 4. Degeneration of pigment epithelium was present in retinal sections from all the deficient animals. The possible role of the pigment epithelium in the pathogenesis of the visual defect in vitamin A deficiency has been discussed. 5. Degenerative changes were noted in Descemet's endothelium. This damage may contribute to the degeneration of the corneal epithelium

Novel duplex vapor electrochemical method for silicon solar cells

Progress in the development of low-cost solar arrays is reported. Topics covered include: (1) development of a simplified feed system for the Na used in the Na-SiF4 reactor; (2) production of high purity silicon through the reduction of sodium fluosilicate with sodium metal; (3) the leaching process for recovering silicon from the reaction products of the SiF4-Na reaction; and (4) silicon separation by the melting of the reaction product

Invalid party wall awards and how to avoid them

Considers the reasons for the invalidity of party wall awards. Examines decided cases under earlier party wall legislation in the context of the Party Wall etc. Act 1996. Explains invalidity on the basis of an excess of the surveyors’ statutory authority. Defines this authority in terms of jurisdiction and power. Demonstrates the limits of the surveyors’ authority and emphasises the importance of strict compliance with statutory procedures. Concludes that surveyors should adopt an inquisitive and analytical approach to the scope of their authority to avoid the possibility of invalid awards. Echoes John Anstey’s earlier warning that surveyors should avoid a broad-brush approach to their duties which will only leave them “covered in soot”