Nonhomogeneous geometric distributions with relations to birth and death processes

In this paper we introduce and study nonhomogeneous geometric random variables and their representations. We relate these to standard probability mass functions and to representations using birth-and-death processes. This facilitates comparison of various queueing models by birth/death models. We examine different queueing models with the same limiting distribution.      

The B(3) Field from Curved Spacetime Embedded in the Irreducible Representation of the Einstein Group

The details of this paper build on the previous work of M. Sachs and M. Evans that describe an enhanced form of general relativity which contains an inherently non-abelian field tensor. We focus on a particular field arising from the non-abelian form of electrodynamics. In particular, the form of this field will be demonstrated in a first-order perturbation approach within the context of a simple manifold, and also the leading order contribution to this field due to the presence of matter. The enhanced form of general relativity, as detailed in [1], is that of antisymmetrized general relativity which relies on the irreducible representation of the Einstein translation group. We also discuss the possibility of an inherent energy induced by curvature.     

Network Model of Flow,Transport and Biofilm Effects in Porous Media

In this paper, we develop a network model to determine porosity and permeability changes in a porous medium as a result of changes in the amount of biomass. The biomass is in the form of biofilms. Biofilms form when certain types of bacteria reproduce, bond to surfaces, and produce extracellular polymer (EPS) filaments that link together the bacteria. The pore spaces are modeled as a system of interconnected pipes in two and three dimensions. The radii of the pipes are given by a lognormal probability distribution. Volumetric flow rates through each of the pipes, and through the medium, are determined by solving a linear system of equations, with a symmetric and positive definite matrix. Transport through the medium is modeled by upwind, explicit finite difference approximations in the individual pipes. Methods for handling the boundary conditions between pipes and for visualizing the results of numerical simulations are developed. Increases in biomass, as a result of transport and reaction, decrease the pipe radii, which decreases the permeability of the medium. Relationships between biomass accumulation and permeability and porosity reduction are presented.     

Non-Thermal Plasma Sources Based on Cometary and Point-to-Ring Discharges

A non-thermal plasma (NTP) is a promising tool against the development of bacterial, viral, and fungal diseases. The recently revealed development of microbial resistance to traditional drugs has increased interest in the use of NTPs. We have studied and compared the physical and microbicidal properties of two types of NTP sources based on a cometary discharge in the point-to-point electrode configuration and a corona discharge in the point-to-ring electrode configuration. The electrical and emission properties of both discharges are reported. The microbicidal effect of NTP sources was tested on three strains of the bacterium Staphylococcus aureus (including the methicillin-resistant strain), the bacterium Pseudomonas aeruginosa, the yeast Candida albicans, and the micromycete Trichophyton interdigitale. In general, the cometary discharge is a less stable source of NTP and mostly forms smaller but more rapidly emerging inhibition zones on agar plates. Due to the point-to-ring electrode configuration, the second type of discharge has higher stability and provides larger affected but often not completely inhibited zones. However, after 60 min of exposure, the NTP sources based on the cometary and point-to-ring discharges showed a similar microbicidal effect for bacteria and an individual effect for microscopic fungi.     

Application of conjugate-gradient-like methods to a hyperbolic problem in porous-media flow

This paper presents the application of a preconditioned conjugate-gradient-like method to a non-self-adjoint problem of interest in underground flow simulation. The method furnishes a reliable iterative solution scheme for the non-symmetric matrices arising at each iteration of the non-linear time-stepping scheme. The method employs a generalized conjugate residual scheme with nested factorization as a preconditioner. Model runs demonstrate significant computational savings over direct sparse matrix solvers.     

Point-group symmetry and transition metal superconductivity: Nb?Mo?Tc alloys

Using a factorization of the band density of states into point-group symmetries, it is shown that the variation of the fractional density of states of one type—Γ₁₂—correlates closely (ρ₁₂ = 0.997) with variations in λM〈ω²〉. It is also shown that the Hopfield parameter η does not correlate with N_p(0)N_d(0)/N(0), which would be true if superconductivity in d-band materials was dominated by local atomic processes. It is concluded that bonding plays an important role in superconductivity in Nb-Mo-Tc alloys.     

Inhibition of DNA polymerization and antifungal specificity of furanocoumarins present in traditional medicines

Antifungal activity is positively correlated to furanocoumarin content in extracts of the traditional phytomedicine northern prickly ash (Zanthoxylum americanum Mill. [Rutaceae]). The specificity of these furanocoumarins in inhibiting replication of DNA was investigated with reference to significant base composition differences between fungal and mammalian mitochondrial DNA. We developed a polymerase chain reaction-based assay to investigate whether (1) furanocoumarins inhibit DNA polymerization and (2) distinct furanocoumarins specifically inhibit DNA replication depending on base composition. Specific inhibition of DNA polymerization by 5-methoxypsoralen and psoralen through high-adenine and thymine (AT) (84.3%) and low-AT (51.9%) DNA, respectively, suggests that furanocoumarins inhibit replicative functions of genomes or of regions within the genome that differ in base composition. Greater overall inhibition of DNA polymerization by Z. americanum husk extracts than with single or mixed furanocoumarins suggests that inhibitory compounds in addition to the major furanocoumarins are present in Z. americanum.