A General Equilibrium Financial Asset Economy with Transaction Costs and Trading Constraints

This paper presents a unified framework for examining the general equilibrium effects of transactions costs and trading constraints on security market trades and prices. The model uses a discrete time/state framework and Kuhn-Tucker theory to characterize the optimal decisions of consumers and financial intermediaries. Transaction costs and constraints give rise to regions of no trade and to bid-ask spreads: their existence frustrate the derivation of standard results in arbitrage-based pricing. Nevertheless, we are able to obtain as dual characterizations of our primal problems, one-sided arbitrage pricing results and a personalized martingale representation of asset pricing. These pricing results are identical to those derived by Jouini and Kallal (1995) using arbitrage arguments. The paper's framework incorporates a number of specialized existing models and results, proves new results and discusses new directions for research. In particular, we include characterizations of intermediaries who hold optimal portfolios; brokers who do not hold portfolios, and consumer-specific transactions costs and trading constraints. Furthermore we show that in the special case of equiproportional transaction costs and a sufficient number of assets, there is an analogue of the arbitrage pricing result for European derivatives where prices are interpreted as mid-prices between the bid-ask spread. We discuss the effects of non-convex transaction technologies on prices and trades.Financial Markets, Transaction Costs, Trading Constraints, Asset Pricing, General Equilibrium, Incomplete Markets

Economic aspects of the bee industry /

B55

Feedforward and feedback control in apraxia of speech: effects of noise masking on vowel production

PURPOSE: This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. METHOD: The authors used noise masking to minimize auditory feedback during speech. Six speakers with AOS and aphasia, 4 with aphasia without AOS, and 2 groups of speakers without impairment (younger and older adults) participated. Acoustic measures of vowel contrast, variability, and duration were analyzed. RESULTS: Younger, but not older, speakers without impairment showed significantly reduced vowel contrast with noise masking. Relative to older controls, the AOS group showed longer vowel durations overall (regardless of masking condition) and a greater reduction in vowel contrast under masking conditions. There were no significant differences in variability. Three of the 6 speakers with AOS demonstrated the group pattern. Speakers with aphasia without AOS did not differ from controls in contrast, duration, or variability. CONCLUSION: The greater reduction in vowel contrast with masking noise for the AOS group is consistent with the feedforward system deficit hypothesis but not with the feedback system deficit hypothesis; however, effects were small and not present in all individual speakers with AOS. Theoretical implications and alternative interpretations of these findings are discussed.R01 DC002852 - NIDCD NIH HHS; R01 DC007683 - NIDCD NIH HH

Student learning of simple orthodontic model analysis using plaster and digital casts

INTRODUCTION: Cast analysis plays an essential role in orthodontic diagnosis. Intraoral scanning to produce digital models is a relatively new but increasingly common practice in graduate orthodontic programs. It is unknown how incorporating digital models in post graduate orthodontic programs will influence student learning of model analysis. The purpose of this study was to investigate the possible differences in learning speed and accuracy of basic orthodontic model analysis using digital models or traditional plaster casts. MATERIALS/METHODS: Two groups of senior dental students participated, one for each mode of cast analysis. A study moderator provided a 15-minute tutorial instructing participants on how to analyze the casts. A standardized scoring sheet was used for data collection. Each group was given five sets of orthodontic models to measure the following parameters: Right molar occlusion, overbite, overjet, arch length, required arch space, crowding, and incisor irregularity. The accuracy of the measurements as well as the time taken to complete all measurements on each model were recorded. Learning as measured by increasing accuracy or decreased time over the group of five casts was determined. Five orthodontic faculty served as the control group. RESULTS: Twenty-five students analyzed plaster casts; forty students analyzed digital casts. Molar occlusion was judged as either correct or incorrect; means of the millimetric measurements of the other parameters were compared between groups using general linear modeling. The digital learning group had 15 measurements that were significantly different from the faculty mean; the plaster learning group had only 2 (p<0.05). Regarding molar occlusion, the plaster group was always more accurate. The time required for the measurements decreased in each group to a similar extent, with the greatest decrease between digital casts 1 and 2. CONCLUSIONS: Senior dental students learned how to analyze plaster orthodontic models more accurately than digital casts. The time required for analysis decreased over 5 trials, but was not significantly different between the groups

Advances of treatment in atypical cartilaginous tumours

Atypical cartilaginous tumours (ACT) are tumours arising in bone and mainly only locally aggressive. Over the last decades, treatment of these tumours has become less and less aggressive, in order to prevent unnecessary complications or functional deficits after surgery. This thesis has reviewed the current literature on surgical treatment of these tumours and the results in our own hands. Moreover, we have studied new technical developments in this field: Computer assisted surgery (CAS) makes real-time navigation during surgery possible, hereby maximizing local precision while minimizing X-ray radiation during the procedure. In addition, we analyzed the application of radiofrequency ablation (RFA) in treatment of ACT in the long bones. The results of this thesis show that scraping out of the tumour is as effective as removal of whole sections of bone. Advantages of this technique is that it has lower complication rates and preserves function better. Results of our own center are comparable to other centers worldwide, in the largest study on these patients to date. CAS has an advantageous role for treatment of ACT, but might be even more of value in more challenging tumours and locations. The use of RFA has resulted in the possibility of treatment in daycare, with even lower complication rates compared to surgery and minimal functional setback after treatment

Coordinate Systems in One and Two Dimensions

Presented to the Faculty of the Graduate School of The University of Kansas In Partial Fulfillment of the Requirements for the Degree of Master of Arts