3,808 research outputs found
The Yang-Mills Vacuum in Coulomb Gauge in D=2+1 Dimensions
The variational approach to the Hamilton formulation of Yang-Mills theory in
Coulomb gauge developed by the present authors previously is applied to
Yang-Mills theory in 2+1 dimensions and is confronted with the existing lattice
data. We show that the resulting Dyson-Schwinger equations (DSE) yield
consistent solutions in 2+1 dimensions only for infrared divergent ghost form
factor and gluon energy. The obtained numerical solutions of the DSE reproduce
the analytic infrared results and are in satisfactory agreement with the
existing lattice date in the whole momentum range.Comment: 20 pages, 6 figure
Infrared analysis of propagators and vertices of Yang--Mills theory in Landau and Coulomb gauge
The infrared behaviour of gluon and ghost propagators, ghost-gluon vertex and
three-gluon vertex is investigated for both the covariant Landau and the
non-covariant Coulomb gauge. Assuming infrared ghost dominance, we find a
unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb
gauge we find two different infrared exponents. We also show that a finite
dressing of the ghost-gluon vertex has no influence on the infrared exponents.
Finally, we determine the infrared behaviour of the three-gluon vertex
analytically and calculate it numerically at the symmetric point in the Coulomb
gauge.Comment: 25 pages, 6 figures, accepted by Phys. Rev. D, references added,
typos correcte
Photonic bandgap plasmonic waveguides
A novel type of a plasmonic waveguide has been proposed featuring an "open"
design that is easy to manufacture, simple to excite and that offers a
convenient access to a plasmonic mode. Optical properties of photonic bandgap
(PBG) plasmonic waveguides are investigated experimentally by leakage radiation
microscopy and numerically using the finite element method confirming photonic
bandgap guidance in a broad spectral range. Propagation and localization
characteristics of a PBG plasmonic waveguide have been discussed as a function
of the wavelength of operation, waveguide core size and the number of ridges in
the periodic reflector for fundamental and higher order plasmonic modes of the
waveguide
Corporate Social Responsibility Through an Economic Lens
Business leaders, government officials, and academics are focusing considerable attention on the concept of “corporate social responsibility” (CSR), particularly in the realm of environmental protection. Beyond complete compliance with environmental regulations, do firms have additional moral or social responsibilities to commit resources to environmental protection? How should we think about the notion of firms sacrificing profits in the social interest? May they do so within the scope of their fiduciary responsibilities to their shareholders? Can they do so on a sustainable basis, or will the forces of a competitive marketplace render such efforts and their impacts transient at best? Do firms, in fact, frequently or at least sometimes behave this way, reducing their earnings by voluntarily engaging in environmental stewardship? And finally, should firms carry out such profit-sacrificing activities (i.e., is this an efficient use of social resources)? We address these questions through the lens of economics, including insights from legal analysis and business scholarship.corporate social responsibility, voluntary environmental performance
Gamma spectrometry supported ethnopedological soil mapping in Tanzania
Within the framework of the Trans-SEC project, financed by BMBF, two food value chains for the Dodoma region in Tanzania were inspected in order to make propositions for improvements reaching from soil preparation to product consumption. For this purpose, rapid and reliable soil mapping approaches were established to obtain information for site-adapted cropping trials. A combination of local soil knowledge and gamma spectrometry assisted soil mapping was applied to create soil maps of two villages in the Dodoma region. Local farmers possess decade-old experience and knowledge of the terrain; gamma spectrometry is a proximal, non-invasive method delivering quick results in the field which can be related to soil types and soil properties. In the course of the mapping procedure, soil type distributions in the landscape and laboratory data were related to gamma signals and correlations were investigated.
In order to get a first idea of landscape and local soils, focus group discussions were carried out and resulted in a preliminary soil map, drawn together with local farmers on high resolution satellite images. On this basis, reference soil profiles of the major soil types were described, sampled and gamma signatures as fingerprints were recorded. The latter served as reference for later soil distinction in the field. In the next step, transect walks with soil samplings and gamma ray measurements were carried out together with local key informants. In addition, plots for later cropping experiments were investigated with gamma spectrometry and soil sampling. On first hand, gamma signals depended on bedrock composition. The signals were, in second order, altered by weathering processes and led to further interpretation opportunities. Soil gamma signatures served well for soil distinction. In the laboratory, major soil nutrients and properties were determined, i.e. total carbon, total nitrogen, pH and plant-available P and K. Gamma data were explored in detail for interpretation and further information extraction possibilities. Relationships between gamma radiation and soil properties, valid for the study area, but also transferable to other studies were examined
Corporate Social Responsibility Through an Economic Lens
Business leaders, government officials, and academics are focusing considerable attention on the concept of "corporate social responsibility" (CSR), particularly in the realm of environmental protection. Beyond complete compliance with environmental regulations, do firms have additional moral or social responsibilities to commit resources to environmental protection? How should we think about the notion of firms sacrificing profits in the social interest? May they do so within the scope of their fiduciary responsibilities to their shareholders? Can they do so on a sustainable basis, or will the forces of a competitive marketplace render such efforts and their impacts transient at best? Do firms, in fact, frequently or at least sometimes behave this way, reducing their earnings by voluntarily engaging in environmental stewardship? And finally, should firms carry out such profit-sacrificing activities (i.e., is this an efficient use of social resources)? We address these questions through the lens of economics, including insights from legal analysis and business scholarship.Corporate Social Responsibility, Voluntary Environmental Performance
Two-Point Functions of Coulomb Gauge Yang-Mills Theory
The functional approach to Coulomb gauge Yang-Mills theory is considered
within the standard, second order, formalism. The Dyson-Schwinger equations and
Slavnov-Taylor identities concerning the two-point functions are derived
explicitly and one-loop perturbative results are presented.Comment: 12 pages, no figure
Variational solution of the Yang-Mills Schr\"odinger equation in Coulomb gauge
The Yang-Mills Schr\"odinger equation is solved in Coulomb gauge for the
vacuum by the variational principle using an ansatz for the wave functional,
which is strongly peaked at the Gribov horizon. A coupled set of
Schwinger-Dyson equations for the gluon and ghost propagators in the Yang-Mills
vacuum as well as for the curvature of gauge orbit space is derived and solved
in one-loop approximation. We find an infrared suppressed gluon propagator, an
infrared singular ghost propagator and a almost linearly rising confinement
potential.Comment: 24 pages, revtex, 13 figure
Self-Consistent Pushing and Cranking Corrections to the Meson Fields of the Chiral Quark-Loop Soliton
We study translational and spin-isospin symmetry restoration for the
two-flavor chiral quark-loop soliton. Instead of a static soliton at rest we
consider a boosted and rotating hedgehog soliton. Corrected classical meson
fields are obtained by minimizing a corrected energy functional which has been
derived by semi-classical methods ('variation after projection'). We evaluate
corrected meson fields in the region 300 MeV \le M \le 600 MeV of constituent
quark masses M and compare them with the uncorrected fields. We study the
effect of the corrections on various expectation values of nuclear observables
such as the root-mean square radius, the axial-vector coupling constant,
magnetic moments and the delta-nucleon mass splitting.Comment: 19 pages, LaTeX, 7 postscript figures included using 'psfig.sty', to
appear in Int.J.Mod.Phys.
Ultrasound monitoring of the influence of different accelerating admixtures and cement types for shotcrete on setting and hardening behaviour
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