52,803 research outputs found
Diffusive synchrotron radiation from extragalactic jets
Flattenings of nonthermal radiation spectra observed from knots and interknot
locations of the jets of 3C273 and M87 in UV and X-ray bands are discussed
within modern models of magnetic field generation in the relativistic jets.
Specifically, we explicitly take into account the effect of the small-scale
random magnetic field, probably present in such jets, which gives rise to
emission of Diffusive Synchrotron Radiation, whose spectrum deviates
substantially from the standard synchrotron spectrum, especially at high
frequencies. The calculated spectra agree well with the observed ones if the
energy densities contained in small-scale and large-scale magnetic fields are
comparable. The implications of this finding for magnetic field generation,
particle acceleration, and jet composition are discussed.Comment: 5 pages with 2 figures, MNRAS Letters, accepte
The beginnings of geography teaching and research in the University of Glasgow: the impact of J.W. Gregory
J.W. Gregory arrived in Glasgow from Melbourne in 1904 to take up the post of foundation Professor of Geology in the University of Glasgow. Soon after his arrival in Glasgow he began to push for the setting up of teaching in Geography in Glasgow, which came to pass in 1909 with the appointment of a Lecturer in Geography. This lecturer was based in the Department of Geology in the University's East Quad. Gregory's active promotion of Geography in the University was matched by his extensive writing in the area, in textbooks, journal articles and popular books. His prodigious output across a wide range of subject areas is variably accepted today, with much of his geomorphological work being judged as misguided to varying degrees. His 'social science' publications - in the areas of race, migration, colonisation and economic development of Africa and Australia - espouse a viewpoint that is unacceptable in the twenty-first century. Nonetheless, that viewpoint sits squarely within the social and economic traditions of Gregory's era, and he was clearly a key 'Establishment' figure in natural and social sciences research in the first half of the twentieth century. The establishment of Geography in the University of Glasgow remains enduring testimony of J.W. Gregory's energy, dedication and foresight
FINANCIAL ANALYSIS OF A PROPOSED LARGE-SCALE ETHANOL COGENERATION PROJECT
Financial analysis of an ethanol/electricity cogeneration plant indicates a rapid payback of investment and a high internal rate of return. This is primarily because cogeneration of steam for generation of electricity and biomass conversion to ethanol results in increased engineering efficiency compared to alternative ethanol alone production processes. Economic sensitivity testing included alternative price levels, interest rates, capacities, costs, and a "stand alone" case with no federal government excise tax subsidies. Supply and price analyses suggest the procurement of locally produced feedstock in Alabama and surrounding states is feasible. The robustness of the economic analysis provides support for consideration of ethanol cogeneration as a currently feasible strategy to utilize excess agricultural production capacity.Resource /Energy Economics and Policy,
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