Contrast enhancement of the gastrointestinal tract on MR images using intravenous gadolinium-DTPA

Gadopentetate dimeglumine was administered intravenously to 16 patients undergoing abdominal magnetic resonance (MR) imaging. T1-weighted and fat-suppressed T1-weighted images were acquired before and after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine. The stomach, small bowel, and colon were analyzed regarding the presence and relative intensity of contrast enhancement. Diffuse enhancement of the gastrointestinal tract wall was observed in all patients following contrast material administration. Such enhancement was most conspicuous on fat-suppressed T1-weighted images. Quantitative measurements indicated that the wall of the gastrointestinal tract enhanced approximately 100% with gadopentetate dimeglumine. This study demonstrates that enhancement of the normal gastrointestinal tract occurs routinely when intravenous gadopentetate dimeglumine is administered, and such enhancement should not be considered indicative of gastrointestinal pathology. Furthermore, it suggests the potential utility for using intravenous rather than orally administered contrast agents to provide enhancement of the gastrointestinal tract on MR images.     

Party alternation,divided government,and fiscal performance within US States

The literature on US state government fiscal performance has examined the role of institutional factors such as budget rules and divided government, but has largely ignored the impact of party alternation. This paper primarily focuses on whether party alternation in the governor’s office affects fiscal performance. Our hypothesis is that frequent party changes create a political environment that impacts fiscal performance. To further assess the impact of party alternation on fiscal performance, we consider our primary hypothesis in conjunction with the degree of division that exists between the governor’s office and the legislature. Using panel data from 37 states between 1971 and 2000 we test the hypothesis that frequent party alternation can be expected to affect fiscal performance and find strong support for the hypothesis. An earlier version of this paper was presented at the 2005 Public Choice Society Meetings. The authors would like to thank the conference participants, William Shughart, Charles Register, Jocelyn Evans, John D. Jackson, Amihai Glazer, and two anonymous referees for their comments. We would also like to thank Craig R. Stiller for his help in the collection of data. Any remaining errors remain the responsibility of the authors.     

Olson's Logic of Collective Action: A Review Article

This comment is offered as a defense of humanistic economics whose feminist credentials have been questioned by Julie Nelson. To her, our contribution is little less than orthodox economics, an ideology enshrining masculine values. We find her arguments based on a clear misreading or misinterpretation of our work. Especially needing correction is her charge that our key notion of a dual self is contaminated by traditional hierarchy and masculinized reason, and the idea of a ‘mushroom man’ operating in a social vacuum. Once her arguments, which we find contrived, are deconstructed it can be readily seen that there remains little difference between her own and our economics.     

Non-parametric estimation of historical volatility

Evolving volatility is a dominant feature observed in most financial time series and a key parameter used in option pricing and many other financial risk analyses. A number of methods for non-parametric scale estimation are reviewed and assessed with regard to the stylized features of financial time series. A new non-parametric procedure for estimating historical volatility is proposed based on local maximum likelihood estimation for the t-distribution. The performance of this procedure is assessed using simulated and real price data and is found to be the best among estimators we consider. We propose that it replaces the moving variance historical volatility estimator.     

Growth Opportunities and the Choice of Leverage, Debt Maturity, and Covenants

We investigate the effect of growth opportunities in a firm's investment opportunity set on its joint choice of leverage, debt maturity, and covenants. Using a database that contains detailed debt covenant information, we provide large‐sample evidence of the incidence of covenants in public debt and construct firm‐level indices of bondholder covenant protection. We find that covenant protection is increasing in growth opportunities, debt maturity, and leverage. We also document that the negative relation between leverage and growth opportunities is significantly attenuated by covenant protection, suggesting that covenants can mitigate the agency costs of debt for high growth firms.     

Shifting reactions to risks: a case study

Social science research in the field of risk analysis has emphasised evaluating the magnitude of individuals’ reactions to risks (e.g. strength and salience of concerns, frequency and forcefulness of behaviours that respond to risks). Fewer studies assess the factors that contribute to risk reactions or the types of risks to which reactions are directed (e.g. human health, wildlife health or ecosystem health risks; economic or aesthetic concerns). Theoretical and empirical research on amplification and attenuation of risk (e.g. the Social Amplification of Risk Framework) reveals that the strength of people’s reaction to risks can change markedly over time, as a function of new stimuli. We expand on this foundation to consider here how the types of risks members of the public react to may also shift over the course of their exposure to a hazard, particularly as more information about the hazard becomes available. This case study of risk reactions related to an outbreak of type E botulism in north-western Michigan, USA, demonstrates that the types of risks people react to can change substantially over time. We identify factors that contributed to changes in types of risk reactions, and then consider how these factors potentially distinguish the botulism outbreak from other outbreaks. This case study suggests that, under certain conditions, risk communication can meaningfully alter the types of risks that people react to in response to an environmental hazard. We discuss implications of these findings for risk research, risk communication and environmental conservation.