1,842 research outputs found

    Kaffircorn malting and brewing studies

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    Utilizing Remote Multispectral Scanner Data and Computer Analysis Techniques

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    This research was designed to study the ability of present automatic computer analysis techniques with the use of multispectral scanner data to differentiate land use categories represented in a complex urban scene and in a selected flightline. An airborne multispectral scanner was used to collect the visible and reflective infrared data. A small subdivision near Lafayette, Indiana was selected as the test site for the urban land use study. Multispectral scanner data were collected over the subdivision on May 1, 1970 from an altitude of 915 meters. The data were collected in twelve wavelength bands from 0.40 to 1.00 micrometers by the scanner. The results indicated that computer analysis of multispectral data can be very accurate in classifying and estimating the natural and man-made materials that characterize land uses in an urban scene. A 1.6 km. wide and 16 km. long flightline located in Sullivan County, Indiana, which represented most major land use categories, was selected for analysis. Multispectral scanner data were collected on three flights from an altitude of 1,500 meters. Energy in twelve wavelength bands from 0.46 to 11.70 micrometers was recorded by the scanner. A new, more objective approach to computer training was developed for analysis of the three dates of data. Emphasis was placed on the standardization of a procedure for analysis of data. The procedure offered faster and consistently good duplication of attained results. The results indicated an ability for automatic computer analysis-of remotely sensed multispectral scanner data to characterize and map land use categories within the test area. Additionally, results indicated an alteration of the data analysis procedure and land use classification scheme

    Modeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models

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    An initial three-station version of the Event Horizon Telescope, a millimeter-wavelength very-long baseline interferometer, has observed Sagittarius A* (Sgr A*) repeatedly from 2007 to 2013, resulting in the measurement of a variety of interferometric quantities. Of particular importance, there is now a large set of closure phases, measured over a number of independent observing epochs. We analyze these observations within the context of a realization of semi-analytic radiatively inefficient disk models, implicated by the low luminosity of Sgr A*. We find a broad consistency among the various observing epochs and between different interferometric data types, with the latter providing significant support for this class of models of Sgr A*. The new data significantly tighten existing constraints on the spin magnitude and its orientation within this model context, finding a spin magnitude of a=0.10−0.10−0.10+0.30+0.56a=0.10^{+0.30+0.56}_{-0.10-0.10}, an inclination with respect to the line of sight of Ξ=60∘−8∘−13∘+5∘+10∘\theta={60^\circ}^{+5^\circ+10^\circ}_{-8^\circ-13^\circ}, and a position angle of Ο=156∘−17∘−27∘+10∘+14∘\xi={156^\circ}^{+10^\circ+14^\circ}_{-17^\circ-27^\circ} east of north. These are in good agreement with previous analyses. Notably, the previous 180∘180^\circ degeneracy in the position angle has now been conclusively broken by the inclusion of the closure phase measurements. A reflection degeneracy in the inclination remains, permitting two localizations of the spin vector orientation, one of which is in agreement with the orbital angular momentum of the infrared gas cloud G2 and the clockwise disk of young stars. This possibly supports a relationship between Sgr A*'s accretion flow and these larger-scale features.Comment: 16 pages, 11 figures, accepted to Ap

    Chlorinated biphenyls and p,p'-DDE in Mediterranean surface waters

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    Individual chlorobiphenyls (CBs) and p,p'-DDE were determined in solution and suspension in surface transects of the open Mediterranean Sea in 1987. Large volumes of sea water (1400—1700 dm3) were analyzed. Concentrations of CBs were low in solution (<5 pg/dm3) and in suspension (<60 pg/dm3). Values for their sum (XCB) were 1.7-43.9 and 190-615 pg/dm3, respectively. Compositions of the CB mixtures in solution as well as those in suspension were very similar in the various transects, but considerable differences were present between solution and suspension in each transect. It was attempted to interpret these differences in terms of molecular characteristics (octanol-water distribution coefficients, Kaw). The resulting plots of log Kovl vs. the apparent distribution coefficient (log K&) gave evidence for the uptake of CBs by suspended particles, followed by sedimentation out of the surface layer. Concentrations in solution were much lower (1-2 orders of magnitude) than those reported before. This may result from improvements in the sampling and analytical techniques. No clear evidence for significant local sources of these compounds was detected in the surface waters, as the levels in solution were very similar to the very low concentrations in the adjacent open Atlantic

    Evidence of reduced surface electron-phonon scattering in the conduction band of Bi_{2}Se_{3} by non-equilibrium ARPES

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    The nature of the Dirac quasiparticles in topological insulators calls for a direct investigation of the electron-phonon scattering at the \emph{surface}. By comparing time-resolved ARPES measurements of the TI Bi_{2}Se_{3} with different probing depths we show that the relaxation dynamics of the electronic temperature of the conduction band is much slower at the surface than in the bulk. This observation suggests that surface phonons are less effective in cooling the electron gas in the conduction band.Comment: 5 pages, 3 figure

    Chlorinated Biphenyls and p,p\u27-DDE in Mediterranean Surface Waters

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    Individual chlorobiphenyls (CBs) and p,p\u27-DDE were determined in solution and suspension in surface transects of the open Mediterranean Sea in 1987. Large volumes of sea water (1400—1700 dm3) were analyzed. Concentrations of CBs were low in solution (<5 pg/dm3) and in suspension (<60 pg/dm3). Values for their sum (XCB) were 1.7-43.9 and 190-615 pg/dm3, respectively. Compositions of the CB mixtures in solution as well as those in suspension were very similar in the various transects, but considerable differences were present between solution and suspension in each transect. It was attempted to interpret these differences in terms of molecular characteristics (octanol-water distribution coefficients, Kaw). The resulting plots of log Kovl vs. the apparent distribution coefficient (log K&) gave evidence for the uptake of CBs by suspended particles, followed by sedimentation out of the surface layer. Concentrations in solution were much lower (1-2 orders of magnitude) than those reported before. This may result from improvements in the sampling and analytical techniques. No clear evidence for significant local sources of these compounds was detected in the surface waters, as the levels in solution were very similar to the very low concentrations in the adjacent open Atlantic

    Inclusive quasielastic electron scattering on 6^6He: a probe of the halo structure

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    We investigate inclusive electron scattering reactions on two-neutron halo nuclei in the quasielastic region. Expressions for the cross section and structure functions are given assuming that the halo nucleus can be described as a three-body system (core+n+n{core}+n+n). The method is applied to 6^6He. We compute cross sections and structure functions, and investigate the kinematic conditions for which the observables are determined either by α\alpha-knockout or by halo neutron-knockout. The optimal kinematical domain to disantangle the momentum distributions of the various components of the three--body system (qâ‰Č200q \lesssim 200 MeV/c and ω<q2/2MN+20\omega < q^2/2M_N + 20 MeV) are explored.Comment: 10 pages, 3 figures. Physics Letters B, in pres

    Cross sections for Coulomb and nuclear breakup of three-body halo nuclei

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    All possible dissociation cross sections for the loosely bound three-body halo nuclei 6^6He (n+n+α\alpha) and 11^{11}Li (n+n+9^{9}Li) are computed as functions of target and beam energy. Both Coulomb and nuclear interactions are included in the same theoretical framework. The measurements agree with the calculations for energies above 100 Mev/nucleon. The largest cross sections correspond to final states with zero or three particles for heavy and with two neutrons for light targets.Comment: 5 pages, 3 figures, revte
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