8,467 research outputs found

    The making of Britain’s first urban landscapes: the case of late Iron Age and Roman Essex

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    This paper presents preliminary research into the social and economic impact of early urban settlement in Britain, focusing on the case-study area of Late Iron Age to Roman Essex. Through fresh analysis of ceramic assemblages from Colchester and Heybridge, we describe hitherto unrecognised socio-cultural groupings and identities through subtle differences in the deposition of pottery in the generations before and after conquest. The concluding discussion concentrates on problems that we still have to address in describing the economic basis of early urban society in Britain

    Improved molecular sorbent trap for high-vacuum systems

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    Closed cycle refrigeration loop in which trays holding molecular sorbent are made to serve as cooling baffles improves the performance of high vacuum systems. High performance is obtained with almost no decrease in pumping speed

    Empirical studies of upper atmospheric species

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    The first month of spin-scan ozone imaging (SOI) data (October 1981) was processed and compared with total ozone mapping spectrometer and ground based data. Short term variations in the ozone field have been revealed using animated sequences of SOI data. High correlations were observed between SOI ozone and upper tropospheric meteorological data. The relationship between ozone and temperature in the stratosphere was investigated by examining Nimbus 4 backscattered ultraviolet ozone and selective chopper radiometer temperature measurements as well as solar Nimbus 7 solar backscattered ultraviolet ozone and stratospheric and mesospheric sounder temperature measurements. Results from these ozone temperature studies were compared with calculations from theoretical 2-D models. All of the lims infrared monitor of the stratosphere data was processed at 10 pressure levels and correlations between various species have been performed. The Venus Atmospheric Drag model was modified taking into account recent investigations on the Venus thermosphere and the resulting model was considered for incorporation into the Venus International Reference Atmosphere

    Composite multilayer insulations for thermal protection of aerospace vehicles

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    Composite flexible multilayer insulation systems (MLI), consisting of alternating layers of metal foil and scrim cloth or insulation quilted together using ceramic thread, were evaluated for thermal performance and compared with a silica fibrous (baseline) insulation system. The systems studied included: (1) alternating layers of aluminoborosilicate (ABS) scrim cloth and stainless steel foil, with silica, ABS, or alumina insulation; (2) alternating layers of scrim cloth and aluminum foil, with silica or ABS insulation; (3) alternating layers of alumininum foil and silica or ABS insulation; and (4) alternating layers of aluminum-coated polyimide placed on the bottom of the silica insulation. The MLIs containing aluminum were the most efficient, measuring as little as half the backface temperature increase of the baseline system

    Proceedings of the 1974 Lyndon B. Johnson Space Center Wheat-Yield Conference

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    The proceedings of the 1974 Lyndon B. Johnson Space Center Wheat-Yield Conference are presented. The state of art of wheat-yield forecasting and the feasibility of incorporating remote sensing into this forecasting were discussed with emphasis on formulating common approach to wheat-yield forecasting, primarily using conventional meteorological measurements, which can later include the various applications of remote sensing. Papers are presented which deal with developments in the field of crop modelling

    Characterizing groupoid C*-algebras of non-Hausdorff \'etale groupoids

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    Given a non-necessarily Hausdorff, topologically free, twisted etale groupoid (G,L)(G, L), we consider its "essential groupoid C*-algebra", denoted Cess(G,L)C^*_{ess}(G, L), obtained by completing Cc(G,L)C_c(G, L) with the smallest among all C*-seminorms coinciding with the uniform norm on Cc(G0)C_c(G^0). The inclusion of C*-algebras (C0(G0),Cess(G,L))(C_0(G^0), C^*_{ess}(G, L)) is then proven to satisfy a list of properties characterizing it as what we call a "weak Cartan inclusion". We then prove that every weak Cartan inclusion (A,B)(A, B), with BB separable, is modeled by a topologically free, twisted etale groupoid, as above. In another main result we give a necessary and sufficient condition for an inclusion of C*-algebras (A,B)(A, B) to be modeled by a twisted etale groupoid based on the notion of "canonical states". A simplicity criterion for Cess(G,L)C^*_{ess}(G, L) is proven and many examples are provided.Comment: New references and a new main result characterizing arbitrary twisted etale groupoid C*-algebras were added. The title was changed to account for the inclusion of the new main result. Still a preliminary versio

    The human, primate and rabbit ultraviolet action spectra

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    A 5000 watt xenon-mercury high pressure lamp was used to produce a continuous ultraviolet spectrum. Human and animal exposures were made to establish the photokeratitis threshold and abiotic action spectrum. The lower limit of the abiotic action spectrum was 220 nm while the upper limit was 310 nm. The radiant exposure threshold at 270 nm was 0.005 watts/sq cm for the rabbit, 0.004 watts/sq cm for the primate, and 0.004 watts/ sq cm for the human. The rabbit curve was bi-peaked with minimums at 220 nm, 240 nm and 270 nm. The primate curve was tri-peaked with minimums at 220 nm, 240 nm and 270 nm. The human data showed a rather shallow curve with a minimum at 270 nm. Formulas and calculations are given to predict minimum exposure times for ocular damage to man in outer space, to establish valid safety criteria, and to establish protective design criteria

    Two force component measuring device Patent

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    Development of two force component measuring devic

    A model atmosphere for earth resources applications

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    Computer subprogram set permitting use of radiosonde data to provide model atmosphere data for earth resources applicatio
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