The Low Column Density Lyman-alpha Forest

We develop an analytical method based on the lognormal approximation to compute the column density distribution of the Lyman-alpha forest in the low column density limit. We compute the column density distributions for six different cosmological models and found that the standard, COBE-normalized CDM model cannot fit the observations of the Lyman-alpha forest at z=3. The amplitude of the fluctuations in that model has to be lowered by a factor of almost 3 to match observations. However, the currently viable cosmological models like the lightly tilted COBE-normalized CDM+Lambda model, the CHDM model with 20% neutrinos, and the low-amplitude Standard CDM model are all in agreement with observations, to within the accuracy of our approximation, for the value of the cosmological baryon density at or higher than the old Standard Bing Bang Nucleosynthesis value of 0.0125 for the currently favored value of the ionizing radiation intensity. With the low value for the baryon density inferred by Hogan & Rugers (1996), the models can only marginally match observations.Comment: three postscript figures included, submitted to ApJ

An experimental investigation of criteria for continuous variable entanglement

We generate a pair of entangled beams from the interference of two amplitude squeezed beams. The entanglement is quantified in terms of EPR-paradox [Reid88] and inseparability [Duan00] criteria, with observed results of $\Delta^{2} X_{x|y}^{+} \Delta^{2} X_{x|y}^{-} = 0.58 \pm 0.02$ and $\sqrt{\Delta^{2} X_{x \pm y}^{+} \Delta^{2} X_{x \pm y}^{-}} = 0.44 \pm 0.01$, respectively. Both results clearly beat the standard quantum limit of unity. We experimentally analyze the effect of decoherence on each criterion and demonstrate qualitative differences. We also characterize the number of required and excess photons present in the entangled beams and provide contour plots of the efficacy of quantum information protocols in terms of these variables.Comment: 4 pages, 5 figure

The effect of legislation on the contractor's attitudes on solid waste reduction

It has been a difficult task to reduce and handle solid wastes generated from construction and demolition (C&D) activities in a number of countries. In Hong Kong, the C&D soHd wastes of which many of them are suitable for recycling land reclamation were typically disposed to landfills. Regarding this, in December 2005, a main piece of legislation regarding the C&D solid waste minimization namely the Construction Waste Disposal Charging Scheme (CWDCS) was enacted in Hong Kong. Since then disposal of C&D solid waste to public landfill sites has no longer been a 'free meal' for the contractors. While the government statistics indicate that the average quantity of C&D solid waste disposed to the public landfill has been tremendously decreased, disgraceful news about the illegal disposal of C&D waste by contractors have begun to mount. Some criticized that the illegal disposal was indeed driven by the legislation. It is because the legislation itself basically cannot solve the problems encountered by the contractors i.e. an effective solid waste reduction and management. As such, a behavioral change of solid waste disposal by the contractors has yet been noted. This study uses the enactment of the CWCS as a benchmark, and seeks to investigate [I] whether the Scheme has prompted the construction contractors to adopt C&D solid wastes reduction strategies in the construction projects; and [2] the effect of the strategy applied by the contractors on C&D solid waste reduction in their projects. A questionnaire survey was conducted. The analysed results based on the Pearson correlation analysis show that the enactment of the CWCS merely led the main contractors reorient their operational practices. Collaboration among project team members in C&D solid waste reduction remains inadequate. Recommendation in response to the research findings was suggested

Energy flux of electromagnetic field in stochastic model of radiative heat transfer in dielectric solid medium

The stochastic model that describes radiative heat tran sfe r in dielectric medium is analyzed. The model is based on the representation that heat tran sfer is realized both by its heat conductivity and by electromagnetic radiation th a t is generated by thermal fluctuations in the medium. Such physical suppositions, using fluctuation-dissipative theorem, are realized in the form of the infinite dimensional Ornstein-Uhlenbeck process that describes medium fluctuation

String Organization of Field Theories: Duality and Gauge Invariance

String theories should reduce to ordinary four-dimensional field theories at low energies. Yet the formulation of the two are so different that such a connection, if it exists, is not immediately obvious. With the Schwinger proper-time representation, and the spinor helicity technique, it has been shown that field theories can indeed be written in a string-like manner, thus resulting in simplifications in practical calculations, and providing novel insights into gauge and gravitational theories. This paper continues the study of string organization of field theories by focusing on the question of local duality. It is shown that a single expression for the sum of many diagrams can indeed be written for QED, thereby simulating the duality property in strings. The relation between a single diagram and the dual sum is somewhat analogous to the relation between a old- fashioned perturbation diagram and a Feynman diagram. Dual expressions are particularly significant for gauge theories because they are gauge invariant while expressions for single diagrams are not.Comment: 20 pages in Latex, including seven figures in postscrip

Gauge Consistent Wilson Renormalization Group II: Non-Abelian Case

We give a wilsonian formulation of non-abelian gauge theories explicitly consistent with axial gauge Ward identitities. The issues of unitarity and dependence on the quantization direction are carefully investigated. A wilsonian computation of the one-loop QCD beta function is performed.Comment: 34 pages, 1 eps figure, latex2e. Minor changes, version to appear in Int. J. Mod. Phy

Higher-order non-symmetric counterterms in pure Yang-Mills theory

We analyze the restoration of the Slavnov-Taylor (ST) identities for pure massless Yang-Mills theory in the Landau gauge within the BPHZL renormalization scheme with IR regulator. We obtain the most general form of the action-like part of the symmetric regularized action, obeying the relevant ST identities and all other relevant symmetries of the model, to all orders in the loop expansion. We also give a cohomological characterization of the fulfillment of BPHZL IR power-counting criterion, guaranteeing the existence of the limit where the IR regulator goes to zero. The technique analyzed in this paper is needed in the study of the restoration of the ST identities for those models, like the MSSM, where massless particles are present and no invariant regularization scheme is known to preserve the full set of ST identities of the theory.Comment: Final version published in the journa