1,880 research outputs found
HDP 2 - A Digital Program Calculation the Surfaces and the Efficiencies of a Heat Exchanger Coupled with a Turbine at Nominal Power and at Part Load. Part I: Description of the code version HD 2 calculating the nominal power characteristics. EUR 4252.
Attentional control of spatial scale: effects on self-organized motion patterns
AbstractPrior to the presentation of a test stimulus, subjectsâ attentional state was either narrowly focused on a particular location or broadly spread over a large spatial region. In previous studies, it was found that broadly spread attention enhances the sensitivity of relatively large spatial filters (increasing the perceiverâs spatial scale), thereby diminishing spatial resolution and enhancing sensitivity to global stimulus structure. In this study it is shown that attentional spread also affects the self-organization of unidirectional versus oscillatory motion patterns for the directionally ambiguous, counterphase presentation of rows of evenly-spaced visual elements (lines segments; dots); i.e. qualitatively different motion patterns can be formed for the same stimulus at different spatial scales. Although the degree to which attention is spread along a spatial axis can be controlled by the perceiver, the effects of spread attention are not limited to a single axis. These results, as well as previously observed effects of attentional spread on spatial resolution, are accounted for by a neural model involving large, foveally-centered receptive fields with co-operatively interacting subunits (probably at the level of MST or higher)
Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature
It is widely believed that magnetic excitations become increasingly
incoherent as temperature is raised due to random collisions which limit their
lifetime. This picture is based on spin-wave calculations for gapless magnets
in 2 and 3 dimensions and is observed experimentally as a symmetric Lorentzian
broadening in energy. Here, we investigate a three-dimensional dimer
antiferromagnet and find unexpectedly that the broadening is asymmetric -
indicating that far from thermal decoherence, the excitations behave
collectively like a strongly correlated gas. This result suggests that a
temperature activated coherent state of quasi-particles is not confined to
special cases like the highly dimerized spin-1/2 chain but is found generally
in dimerized antiferromagnets of all dimensionalities and perhaps gapped
magnets in general
Magnetic ground state of the Kitaev NaCoTeO spin liquid candidate
As a candidate Kitaev material, NaCoTeO exhibits intriguing
magnetism on a honeycomb lattice that is believed to be -symmetric. Here
we report a neutron diffraction study of high quality single crystals under
-axis magnetic fields. Our data support the less common notion of a magnetic
ground state that corresponds to a triple- magnetic structure with
symmetry, rather than the multi-domain zigzag structure typically assumed
in prototype Kitaev spin liquid candidates. In particular, we find that the
field is unable to repopulate the supposed zigzag domains, where the only
alternative explanation is that the domains are strongly pinned by hitherto
unidentified structural reasons. If the triple- structure is
correct then this requires reevaluation of many candidate Kitaev materials. We
also find that fields beyond about 10 Tesla suppress the long range
antiferromagnetic order, allowing new magnetic behavior to emerge different
from that expected for a spin liquid.Comment: 4 pages, 4 figures, plus Supplemental Materia
Orientation Study on the Economic Potential of an Orgel Power Plant Equipped with a G-30 Fuel Element. EUR 4251.
Investigation of ground deformation in Taiyuan Basin, China from 2003 to 2010, with atmosphere-corrected time series InSAR
Excessive groundwater exploitation is common through the Taiyuan basin, China, and is
well known to result in ground subsidence. However, most ground subsidence studies in this
region focus on a single place (Taiyuan city), and thus fail to demonstrate the regional extent of
the deformation phenomena in the whole basin. In this study, we used Interferometric Synthetic
Aperture Radar (InSAR) time series analysis to investigate land subsidence across the entire Taiyuan
basin region. Our data set includes a total of 75 ENVISAT ASAR images from two different frames
acquired from August 2003 to September 2010 and 33 TerraSAR-X scenes spanning between March
2009 and March 2010. ERA-Interim reanalysis was used to correct the stratified delay to reduce
the bias expected from the systematic components of tropospheric delay. The residual delay after
correction of stratified delay can be considered as a stochastic component and be mitigated through
spatial-temporal filtering. A comparison with MERIS (Medium-Resolution Imaging Spectrometer)
measurements indicates that our atmospheric corrections improved agreement over the conventional
spatial-temporal filtering by about 20%. The displacement results from our atmosphere-corrected
time series InSAR were further validated with continuous GPS data. We found eight subsiding centers
in the basin and a surface uplift to the north of Taiyuan city. The causes of ground deformation are
analyzed and discussed in relation to gravity data, pre-existing faults, and types of land use
Effects of urban stream burial on organic matter dynamics and reach scale nitrate retention
Nitrogen (N) retention in streams is an important ecosystem service that may be affected by the widespread burial of streams in stormwater pipes in urban watersheds. We predicted that stream burial suppresses the capacity of streams to retain nitrate (NO3 â) by eliminating primary production, reducing respiration rates and organic matter availability, and increasing specific discharge. We tested these predictions by measuring whole-stream NO3 â removal rates using 15NO3 â isotope tracer releases in paired buried and open reaches in three streams in Cincinnati, Ohio (USA) during four seasons. Nitrate uptake lengths were 29 times greater in buried than open reaches, indicating that buried reaches were less effective at retaining NO3 â than open reaches. Burial suppressed NO3 â retention through a combination of hydrological and biological processes. The channel shape of two of the buried reaches increased specific discharge which enhanced NO3 â transport from the channel, highlighting the relationship between urban infrastructure and ecosystem function. Uptake lengths in the buried reaches were further lengthened by low stream biological NO3 â demand, as indicated by NO3 â uptake velocities 17-fold lower than that of the open reaches. We also observed differences in the periphyton enzyme activity between reaches, indicating that the effects of burial cascade from the microbial to the ecosystem scale. Our results suggest that stream restoration practices involving âdaylightingâ buried streams have the potential to increase N retention. Further work is needed to elucidate the impacts of stream burial on ecosystem functions at the larger stream network scale
Head of State of Exception
During the escalation of the âGerman Autumnâ in 1977 the Federal German government resorted to a specific form of crisis management that had been described as an undeclared state of exception. It was Federal chancellor Helmut Schmidt in the first place who oversaw the anti-terrorist measures in the situation room where the executive branch ruled for six weeks beyond any parliamentary control. This article examines the role that Helmut Schmidt had played for the creation of a âsubjective state of exceptionâ (Julius Hatschek) and how this could be seen as stemming from Schmidtâs earlier experiences and handling of crisis situations dating back to the 1960s. In this regard it has to be asked with Giorgio Agamben, if in the West German case, the state of exception had become the rule
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