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In this work, we demonstrate a high mobility two-dimensional electron gas (2DEG) formed at the beta-(AlxGa1-x)(2)O-3/Ga2O3 interface through modulation doping. Shubnikov-de Haas (SdH) oscillations were observed in the modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 structure, indicating a high-quality electron channel formed at the heterojunction interface. The formation of the 2DEG channel was further confirmed by the weak temperature dependence of the carrier density, and the peak low temperature mobility was found to be 2790 cm(2)/Vs, which is significantly higher than that achieved in bulk-doped Beta-phase Gallium Oxide (beta-Ga2O3). The observed SdH oscillations allowed for the extraction of the electron effective mass in the (010) plane to be 0.313 +/- 0.015 m(0) and the quantum scattering time to be 0.33 ps at 3.5K. The demonstrated modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 structure lays the foundation for future exploration of quantum physical phenomena and semiconductor device technologies based on the beta-Ga2O3 material system. Published by AIP Publishing.

"Some currently proposed strategies for educational and employment selection are based on a group-parity concept of fairness towards groups of persons... We suggest that a socially desirable and constitutionally acceptable selection strategy can be fashioned more readily by the formalism of statistical decision theory."

The level of active return, the volatility of active return, and the covariance structure of active return are three important dimensions of active management for understanding optimal portfolio structure. An optimal portfolio structure is highly sensitive to various assumptions about the covariance structure of active return; it varies with both the degree of diversification in active returns and the number of unique sources of active return. If the sources of active return are not diversified, investors should make a substantial allocation to risk-controlled active strategies. As there are more separate sources of active return or greater diversification among those sources, the optimal allocation to index strategies and risk-controlled active strategies may be lower.

This paper develops a two-country international business-cycle model with variable capital utilization, using a standard depreciation-in-use technology. Variable capital utilization significantly reduces the required size of productivity shocks needed to replicate observed output volatility by 20–40%. Further, the model generates positive comovement across countries in wages, hours, and investment, while preserving empirically accurate predictions regarding the relative cross-country correlations of output and consumption and the countercyclical behavior of net exports. Finally, accounting for variable capital utilization reduces cross-country correlation of true productivity shocks relative to that of the standard Solow residual.

For many private investors, tax efficiency is often addressed by employing investment managers with low portfolio turnover or by incorporating a “tax efficient core” as part of a more diversified portfolio. In this paper, the author suggests that there are situations where the pursuit of tax efficiency can and should take place outside of an investor9s core portfolio. His proposed solution, ironically, relies on hedge funds, which are notoriously known as tax inefficient investment strategies. He maintains that certain types of hedge funds—when managed appropriately—can be excellent vehicles for increasing the tax efficiency of a portfolio.

This research tested hypotheses that negative evaluations of important roles predict vulnerability to stress-related increases in psychological distress, that stressful events are related to increases in distress in part by increasing negative role evaluations, and that domain-specific measures are superior to aggregate measures in making such predictions. In a prospective study controlling for social desirability and initial symptoms, negative role evaluations were associated with increased vulnerability to dysphoric, but not anxious, reactions to negative life events. Negative events were associated with increases in negative role evaluations over time, and these increases accounted for much of the stress—symptom relation. Aggregate measures were better predictors of stress vulnerability, but domain-specific measures had an advantage in analyses of cognitive mediators of life events. Thus, the advantages of using aggregate vs. domain-specific measures may depend upon the aspect of the stress process under investigation.

Dynamic factor models are widely used in modern portfolio management. These models are based on factors such as equity style, industry or geographic location, macroeconomic factors (e.g., the term structure of interest rates, credit spreads, inflation, and GDP growth), or microeconomic factors (e.g., beta, liquidity, profitability, or leverage). Modeling of the time series variation in factor exposure is based on a variety of methods, including relative value spreads, momentum and trends, as well as other combinations. The implementation of these strategies is challenging, but it has been facilitated by new developments in modeling, benchmarking, computing power, and trading technology. Implementation may be achieved at the macro level—via direct exposure to one or more factors—or at the micro level through factor based security selection models. Keywords: portfolio management; style management; factor models; tactical asset allocation; portfolio attribution; return attribution; fundamental factors; momentum; valuation; indexes; exchange-traded funds (ETFs)

This paper explores how accounting for variations in factor utilization rates alters the empirical characteristics of productivity residuals in the United States and Canada. Using data on 19 manufacturing industries, we study the behavior of productivity using three proxies for capital services. We find that adjusting for cyclical movements in capital utilization alters many of the empirical characteristics of productivity, both within and across countries.