An Australian abroad : the secret life of the brushtail possum (Trichosurus vulpecula) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatu, New Zealand

The “superspreader” hypothesis relates disease transmission to social contacts and assumes transmission is driven by the frequency, type and distribution of contacts among infected and susceptible individuals. I investigated characteristics of brushtail possum (Trichosurus vulpecula) home ranges for six wild free-living subpopulations, (four grids were studied; all of them before possum depopulation and two of them after possum depopulation) constructing social networks relevant to bovine tuberculosis (TB) transmission before and after depopulation. I also experimentally infected possums with a novel strain of TB to monitor secondary case infections in relation to these contact and other factors, including population density and sex ratio. Before depopulation home range estimates showed adult males had larger home ranges than female and younger possums. Home range overlap and area of overlap differed between subpopulations, and possum sex and age; with adult males having more and larger overlaps with other possums. Possums were fitted with proximity-logging collars and contacts registered between April and October, 2012. The number of connections an individual has with others and the probability of the distribution of contacts it has within the population, or node degree and betweenness, also known as the shortest distance between individuals, were associated with sex, with males having higher values for each. Males also contacted more possums than females. Post-depopulation results showed an influx of male possums, higher population density, and smaller home range sizes than before depopulation. Possums post-depopulation also lacked an apparent ‘routine’ in contact networks, interacting with other possums haphazardly. The greater level of contact among adult males, than before depopulation, and their effects on recovering populations post-depopulation, was likely the cause of more TB infection in adults and males. This thesis provides empirical evidence that adult male possums have home range and contact network characteristics that are likely to enhance their involvement in the transmission and persistence of TB, relative to female and younger possums. Observations of experimentally infected individuals showed that infected males survived longer than females and that, as a consequence, those males potentially acted as a “supershedding” subgroup. I therefore provide evidence that adult male possums are the most important drivers of TB transmission and persistence of infection in populations, and could be targeted for control measures

BACKWARD IMPLICIT CONTRACTS, PRE-COMMITMENT AND MARKET POWER IN THE INTERNATIONAL DURUM WHEAT MARKET

We devise a formal test of market power that is applied to the international durum market. The model captures the asymmetric cost structure brought about the initial payment system of the Canadian Wheat Board. The model generates testable hypotheses about market conduct and optimal strategic positioning.Crop Production/Industries, Industrial Organization,

Cybernetic Implications for the U.C.C.

In the following iBrief, the authors assess the impact of recent a recent decision from the 9th Circuit assessing whether the patent system\u27s filing mechanism preempts the U.C.C. Article 9 requirement that creditors perfect their security interests in patents offered as collateral by their debtors

Patent Amendments and Prosecution History Estoppel Under Festo

On November 29, 2000, the Federal Circuit retroactively reduced the value of nearly 1.2 million unexpired United States patents by announcing a new rule for the somewhat obscure doctrine of prosecution history estoppel. Designed to foster clarity in patent applications, this new pronouncement in Festo Corp v. Shoketsu Kinzoku Kogyo Kabushiki Co. allows for easy copying of some patented inventions and reduces patent owner\u27s ability to prove infringement. This article outlines the change in the law and discusses the positive and negative consequences of the decision

Oligopsony Power: Evidence from the U.S. Beef Packing Industry

Replaced with revised version of paper 08/24/09.Margin, Beef Packing, Fed Cattle Prices, Markov Regime Switching, Industrial Organization,

Who’s Afraid of amazon.com v. barnesandnoble.com?

On October 2, 2000, the Court of Appeals for the Federal Circuit heard the appeal in the case of Amazon.com, Inc. v. Barnesandnoble.com, Inc. This appeal revolves around the alleged infringement by Barnesandnoble.com of a one-click web-shopping system patented by Amazon.com. The one-click system is among a series of recent controversial business method patents. According to some, business methods are legitimate inventions that deserve the protection of the US Patent and Trademark Office (PTO). According to others, business methods are unworthy of patent protection and may inhibit innovation in e-commerce. The outcome of this case has been widely anticipated by both sides of the business method patent debate as a signal that these patents will or will not be upheld by courts

How Does Advertising Affect Market Performance? The Case of Generic Advertising

The effect of advertising on market performance has been a long-standing debate. Advertising that increases the dispersion of consumers’ valuations for advertised goods raises the market power of firms, while advertising that decreases the dispersion of consumers’ valuations leads to narrower price-cost margins and superior performance in markets for advertised goods. Numerous challenges confound the empirical identification of advertising effects on market performance. This paper proposes a simple method that relies on the revealed preferences of firms participating in generic advertising programs. Generic advertising programs provide a unique window through which to observe advertising effects on market performance, because changes in the dispersion of consumers’ valuations systematically redistributes rents among firms according to observable characteristics on producer size. We examine producer attitudes towards generic advertising in the “Beef. It’s What’s for Dinner” campaign of the U.S. Beef Checkoff program and find the likelihood a producer favors an expansion of the advertising program increases in operating scale. This finding is consistent with advertising effects that have led to a decrease in the dispersion of consumers’ valuations for beef products and a commensurate increase in market performance.Advertising, Oligopoly, Marketing, L1, M37,

Computationally designed variants of Escherichia coli chorismate mutase show altered catalytic activity

Computational protein design methods were used to predict five variants of monofunctional Escherichia coli chorismate mutase expected to maintain catalytic activity. The variants were tested experimentally and three active site mutants exhibited catalytic activity similar to or greater than the wild-type enzyme. One mutant, Ala32Ser, showed increased catalytic efficiency

Exhaustive mutagenesis of six secondary active-site residues in Escherichia coli chorismate mutase shows the importance of hydrophobic side chains and a helix N-capping position for stability and catalysis

Secondary active-site residues in enzymes, including hydrophobic amino acids, may contribute to catalysis through critical interactions that position the reacting molecule, organize hydrogen-bonding residues, and define the electrostatic environment of the active site. To ascertain the tolerance of an important model enzyme to mutation of active-site residues that do not directly hydrogen bond with the reacting molecule, all 19 possible amino acid substitutions were investigated in six positions of the engineered chorismate mutase domain of the Escherichia coli chorismate mutase-prephenate dehydratase. The six secondary active-site residues were selected to clarify results of a previous test of computational enzyme design procedures. Five of the positions encode hydrophobic side chains in the wild-type enzyme, and one forms a helix N-capping interaction as well as a salt bridge with a catalytically essential residue. Each mutant was evaluated for its ability to complement an auxotrophic chorismate mutase deletion strain. Kinetic parameters and thermal stabilities were measured for variants with in vivo activity. Altogether, we find that the enzyme tolerated 34% of the 114 possible substitutions, with a few mutations leading to increases in the catalytic efficiency of the enzyme. The results show the importance of secondary amino acid residues in determining enzymatic activity, and they point to strengths and weaknesses in current computational enzyme design procedures