2,896 research outputs found
Signatures of Confinement in Axial Gauge QCD
A comparative dynamical study of axial gauge QED and QCD is presented.
Elementary excitations associated with particular field configurations are
investigated. Gluonic excitations analogous to linearly polarized photons are
shown to acquire infinite energy. Suppression of this class of excitations in
QCD results from quantization of the chromelectric flux and is interpreted as a
dual Meissner effect, i.e. as expulsion from the QCD vacuum of chromo-electric
fields which are constant over significant distances. This interpretation is
supported by a comparative evaluation of the interaction energy of static
charges in the axial gauge representation of QED and QCD.Comment: 22 pages (no figures
Noteworthy: hurricane season, venture capital, exports
Ike deals severe blow to Texas economy. Texas investment funding slips in 2nd quarter. Latin America, China lead Texas surge in overseas sales.Economic conditions - Texas ; Natural disasters ; Venture capital - Texas ; International trade ; Exports
London Calling to the Underground: Waste Heat in Urban Morphology is Going Down the Tube
Buildings in urban areas are entirely lacking in significant energy-use developments. Energy production and distribution in urban areas are hugely inefficient, losing most of their production to waste heat. Over the past 100 years, the clay surrounding London’s Underground has warmed and is no longer able to absorb the trapped waste heat, causing the Underground temperature to increase to over 30°C
First results on a process-oriented rain area classification technique using Meteosat Second Generation SEVIRI nighttime data
A new technique for process-oriented rain area classification using Meteosat Second Generation SEVIRI nighttime data is introduced. It is based on a combination of the Advective Convective Technique (ACT) which focuses on precipitation areas connected to convective processes and the Rain Area Delineation Scheme during Nighttime (RADS-N) a new technique for the improved detection of stratiform precipitation areas (e.g. in connection with mid-latitude frontal systems). The ACT which uses positive brightness temperature differences between the water vapour (WV) and the infrared (IR) channels (&Delta;T<sub>WV-IR</sub>) for the detection of convective clouds and connected precipitating clouds has been transferred from Meteosat First Generation (MFG) Metesoat Visible and Infra-Red Imager radiometer (MVIRI) to Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI). RADS-N is based on the new conceptual model that precipitating cloud areas are characterised by a large cloud water path (<i>cwp</i>) and the presence of ice particles in the upper part of the cloud. The technique considers information about both parameters inherent in the channel differences &Delta;T<sub>3.9-10.8</sub>, &Delta;T<sub>3.9-7.3</sub>, &Delta;T<sub>8.7-10.8</sub>, and &Delta;T<sub>10.8-12.1</sub>, to detect potentially precipitating cloud areas. All four channel differences are used to gain implicit knowledge about the <i>cwp</i>. &Delta;T<sub>8.7-10.8</sub> and &Delta;T<sub>10.8-12.1</sub> are additionally considered to gain information about the cloud phase. First results of a comparison study between the classified rain areas and corresponding ground based radar data for precipitation events in connection with a cold front occlusion show encouraging performance of the new proposed process-oriented rain area classification scheme
Discriminating raining from non-raining clouds at mid-latitudes using Meteosat Second Generation daytime data
International audienceA new method for the delineation of precipitation during daytime using multispectral satellite data is proposed. The approach is not only applicable to the detection of mainly convective precipitation by means of the commonly used relation between infrared cloud top temperature and rainfall probability but enables also the detection of stratiform precipitation (e.g. in connection with mid-latitude frontal systems). The presented scheme is based on the conceptual model that precipitating clouds are characterized by a combination of particles large enough to fall, an adequate vertical extension (both represented by the cloud water path (cwp)), and the existence of ice particles in the upper part of the cloud. The technique considers the VIS0.6 and the NIR1.6 channel to gain information about the cloud water path. Additionally, the channel differences ?T8.7-10.8 and ?T10.8-12.1 are considered to supply information about the cloud phase. Rain area delineation is realized by using a minimum threshold of the rainfall confidence. To obtain a statistical transfer function between the rainfall confidence and the channel differences, the value combination of the four variables is compared to ground based radar data. The retrieval is validated against independent radar data not used for deriving the transfer function and shows an encouraging performance as well as clear improvements compared to existing optical retrieval techniques using only IR thresholds for cloud top temperature
Covariant boost and structure functions of baryons in Gross-Neveu models
Baryons in the large N limit of two-dimensional Gross-Neveu models are
reconsidered. The time-dependent Dirac-Hartree-Fock approach is used to boost a
baryon to any inertial frame and shown to yield the covariant energy-momentum
relation. Momentum distributions are computed exactly in arbitrary frames and
used to interpolate between the rest frame and the infinite momentum frame,
where they are related to structure functions. Effects from the Dirac sea
depend sensitively on the occupation fraction of the valence level and the bare
fermion mass and do not vanish at infinite momentum. In the case of the kink
baryon, they even lead to divergent quark and antiquark structure functions at
x=0.Comment: 13 pages, 12 figures; v2: minor correction
An Alliance Unravels
On 1 September 1951, representatives of Australia , New Zealand , and the United States met in San Fran cisco to sign a treaty of alliance commonly known as the Anzus pact.1 The signing ceremony had been preceded by two years of sporadic negotiations during which the Australians had pressed hard for joint military planning and discu ssion of global strategy. The Americans, however, had been determined to limit formal security arrangements to the minimum necessary to win the consent of their negotiating partners to the relatively mild peace treaty the United States intended to sign with Japan.2 The American view prevailed, and Anzus thus came into being with a council charged with considering matters related to the implementation of the treaty but with no standing military organization and no integrated military force
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