Interactive Feedforward for Improving Performance and Maintaining Intrinsic Motivation in VR Exergaming

Exergames commonly use low to moderate intensity exercise protocols. Their effectiveness in implementing high intensity protocols remains uncertain. We propose a method for improving performance while maintaining intrinsic motivation in high intensity VR exergaming. Our method is based on an interactive adaptation of the feedforward method: a psychophysical training technique achieving rapid improvement in performance by exposing participants to self models showing previously unachieved performance levels. We evaluated our method in a cycling-based exergame. Participants competed against (i) a self model which represented their previous speed; (ii) a self model representing their previous speed but increased resistance therefore requiring higher performance to keep up; or (iii) a virtual competitor at the same two levels of performance. We varied participants' awareness of these differences. Interactive feedforward led to improved performance while maintaining intrinsic motivation even when participants were aware of the interventions, and was superior to competing against a virtual competitor

A Machine Learning Approach to the Interpretation of Cardiopulmonary Exercise Tests: Development and Validation

Objective. At present, there is no consensus on the best strategy for interpreting the cardiopulmonary exercise test’s (CPET) results. This study is aimed at assessing the potential of using computer-aided algorithms to evaluate CPET data for identifying chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD). Methods. Data from 234 CPET files from the Pulmonary Institute, at Sheba Medical Center, and the Givat-Washington College, both in Israel, were selected for this study. The selected CPET files included patients with confirmed primary CHF (n=73), COPD (n=75), and healthy subjects (n=86). Of the 234 CPETs, 150 (50 in each group) tests were used for the support vector machine (SVM) learning stage, and the remaining 84 tests were used for the model validation. The performance of the SVM interpretive module was assessed by comparing its interpretation output with the conventional clinical diagnosis using distribution analysis. Results. The disease classification results show that the overall predictive power of the proposed interpretive model ranged from 96% to 100%, indicating very high predictive power. Furthermore, the sensitivity, specificity, and overall precision of the proposed interpretive module were 99%, 99%, and 99%, respectively. Conclusions. The proposed new computer-aided CPET interpretive module was found to be highly sensitive and specific in classifying patients with CHF or COPD, or healthy. Comparable modules may well be applied to additional and larger populations (pathologies and exercise limitations), thereby making this tool powerful and clinically applicable

Comparative Tax Law: Theory and Practice

On 3 October 2009, a Conference on Comparative Tax Law in Theory and Practice took place at the University of Michigan Law School. It was organized by Reuven Avi-Yonah (Professor, University of Michigan Law School) and Mathias Reimann (Editor, American Journal of Comparative Law and Professor, University of Michigan Law School), and was attended by Hugh Ault (Professor of Law, Boston College Law School), Victor Thuronyi (Senior Counsel, International Monetary Fund), Brian Arnold (Professor Emeritus, University of Western Ontario), William Barker (Professor, The Dickinson School of Law, Penn State), Michael Livingston (Professor, Rutgers School of Law-Camden), Carlo Garbarino (Professor of Taxation, Bocconi University, Milan), Assaf Likhovski (Associate Professor, Tel Aviv University Faculty of Law and Visiting Professor, UCLA Law School), Omri Marian (Scientiae Juridicae Doctor (SJD), University of Michigan Law School), and Nicola Sartori (International University College, Turin and SJD, University of Michigan Law School)

Comparison of thermoregulatory responses to exercise in dry heat among prepubertal boys, young adults and older males

The purpose of this investigation was to compare the thermoregulatory responses during exercise in a hot climate among three age categories. Eight prepubertal (PP), eight young adult (Y) and eight elderly (O) male subjects cycled at an intensity of 50 ± 1% of their maximum oxygen uptake (V[subscript]o2peak) for 85 min (three 20 min bouts with three 7 min rest periods) in hot and dry conditions (41 ± 0.67ºC, 21 ± .%.. relative humidity). During the exercise-in-heat protocol, rectal temperature (T[subscript]re) skin temperatures (T[subscript]sk), heart rate (HR), V[subscript]O2, V[subscript]CO2, Vsubscript]E, RER, sweat rate, and the number of heat activated sweat glands (HASG) were determined. Despite highest and lowest end-exposure T[subscript]re in the Y and O groups, respectively, the rise in rectal temperature (accounting for differences in baseline T[subscript]re) was similar in all age groups. Changes in body heat storage (Delta S), both absolute and relative to body mass, were highest in the Y and O groups and lowest in the PP group. While end-session as well as changes inmean skin temperature were similar in all three age groups, HR (absolute and percentage of maximum) was significantly lower for the O compared with the PP and Y groups. Total body as well as per body surface sweating rate was significantly lower for the PP group, while body mass-related net metabolic heat production ((M - W) kg [superscript]-1) and heat gained from the environment were highest in the PP and lowest in the O group. Since mass-related evaporative cooling (E[subscript]sk kg [superscript]-1) and sweating efficiency (E[subscript]sk/M[subscript]sw kg[superscript]-1) were highest in the PP and lowest in the O group, the mass-dependent heat stored in the body (Delta S kg[superscript]-1) was lowest in the PP (1.87± 0.03 W kg[superscript]-1) and highest in Y and O groups (2.19 ± 0.08 and1.97 ± 0.11 W kg [superscript]-1, respectively). Furthermore, it was calculated that while the O group required only 4.1 ± 0.5 W of heat energy to raise their body core temperature by 1ºC, and the Y group needed 6.9 ± 0.9 W(1º C)[superscript]-1, the PP group required as much as 12.3 ± 0.7 W to heat up their body core temperature by 1ºC. These results suggest that in conditions similar to those imposed during this study, age and age-related characteristics affect the overall rate of heat gain as well as the mechanisms through which this heat is being dissipated. While prepubertal boys seem to be the most efficient thermoregulators, the elderly subjects appear to be the least efficient thermoregulators