Topological Density and Instantons on a Lattice

We present an update on the study of topological structure of QCD. Issues addressed include a comparison between the plaquette and the geometric methods of calculating the topological density. We show that the improved gauge action based on sqrt(3) blocking transformation suppresses the formation of topologically charged dislocations with low action. Using a cooling method we identify the instantons' location, estimate their size and density, and calculate the renormalization constant Z_Q for the plaquette method.Comment: 3 Pages, submitted to Proceedings of XII International Symposium on Lattice Field Theory (Lattice 94, Bielefeld). uuencoded tar file includes figures as TeXDraw (.tex) file

The evolution of the stellar populations in low surface brightness galaxies

We investigate the star formation history and chemical evolution of low surface brightness (LSB) disk galaxies by modelling their observed spectro-photometric and chemical properties using a galactic chemical and photometric evolution model incorporating a detailed metallicity depen dent set of stellar input data. For a large fraction of the LSB galaxies in our sample, observed properties are best explained by models incorporating an exponentially decreasing global star formation rate (SFR) ending at a present-day gas fraction (M_{gas}/(M_{gas}+M_{stars}) = 0.5 for a galaxy age of 14 Gyr. For some galaxies small amplitude star formation bursts are required to explain the contribution of the young (5-50 Myr old) stellar population to the galaxy integrated luminosity. This suggests that star formation has proceeded in a stochastic manner. The presence of an old stellar population in many late-type LSB galaxies suggests that LSB galaxies roughly follow the same evolutionary history as HSB galaxies, except at a much lower rate. In particular, our results imply that LSB galaxies do not form late, nor have a delayed onset of star formation, but simply evolve slowly.Comment: To be published in A&

Use of untreated wastewater in peri-urban agriculture in Pakistan: risks and opportunities

Water reuse / Waste waters / Water quality / Groundwater / Irrigation practices / Soil properties / Environmental effects / Conjunctive use / Pakistan / Haroonabad

Dynamic model of gene regulation for the lac operon

Gene regulatory network is a collection of DNA which interact with each other and with other matter in the cell. The lac operon is an example of a relatively simple genetic network and is one of the best-studied structures in the Escherichia coli bacteria. In this work we consider a deterministic model of the lac operon with a noise term, representing the stochastic nature of the regulation. The model is written in terms of a system of simultaneous first order differential equations with delays. We investigate an analytical and numerical solution and analyse the range of values for the parameters corresponding to a stable solution

Plain Packaging, Pictorial Warnings and Tobacco Products: An Empirical Assessment

Although tobacco marketing is restricted, tobacco product packaging continues to communicate brand imagery, thereby maintaining brand salience and potentially reducing the impact of health warnings. This study used respondent conditioning theory to predict how disruption of brand imagery would affect the attractiveness of known, unknown and generic tobacco packages. A best-worst study found that familiar branding offset the negative connotations created by a pictorial warning label (PWL). These are the first findings to document the combined effect of PWLs and plain packaging; they suggest generic packs will stimulate cessation attempts and deter smoking initiation

Risks, Benefits and DTC - An Analysis of Information Formats

Critics of direct to consumer prescription medicine advertising (DTC) claim it is unbalanced because benefit information features more prominently than risk information, and that it thus fails to meet the high standards of social responsibility called for in regulatory codes. We used respondent conditioning theory to examine whether variations in risk information format could improve recall of benefits, side effects and contra-indications in print DTC advertisements. A best-worst study confirmed striking differences in preference for varied information formats, while a second study found that visual heuristics increased recall of both risk and benefit information. The findings question marketers reluctance to provide easily accessible risk information and suggest prominent drug information panels may discharge manufacturers social responsibilities while simultaneously improving the effectiveness of their promotions

Optimal linear estimation and data fusion

©2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Optimal mean square linear estimators are determined for general uncorrelated noise. We allow the noise variance matrix in the observation process to be singular. This requires properties of generalized inverses which are developed in Section II. The proofs appear to be new. When there are two observation sequences the optimal method of recursively fusing the two is determined. We derive a new formula for the covariance of the two estimates which then provides exact dynamics for a fused estimate.Elliott, R.J. ; van der Hoek, J

Testing the heating method with perturbation theory

The renormalization constants present in the lattice evaluation of the topological susceptibility can be non-perturbatively calculated by using the so-called heating method. We test this method for the $O(3)$ non-linear $\sigma$-model in two dimensions. We work in a regime where perturbative calculations are exact and useful to check the values obtained from the heating method. The result of the test is positive and it clarifies some features concerning the method. Our procedure also allows a rather accurate determination of the first perturbative coefficients.Comment: 15 pages, LaTeX file, needs RevTeX style. Tarred, gzipped, uuencode