This paper presents the results of a simulation study designed to show how a moderator variable affects the form of the relationship between two other variables. Particular attention is paid to the relationship of the strength of a moderator to statistical significance and the magnitude of the increment in R2 associated with the moderator. The increment in R2 is viewed as an incomplete measure of the strength of moderator effects. We propose a standardized measure of the strength of moderator effects based on the rate of change in the slope of the regression surface. The relation of sample size and statistical power to this measure is investigated.

This paper uses a game–theoretic approach to analyse the taxation of interest income in Europe in the presence of tax evasion. The model allows us to assess the success of various reform proposals. We argue that the tax treatment of nonresidents' interest income plays a crucial role. When decisions on discrimination and on withholding tax rates are made non‐cooperatively, the outcome is similar to a prisoners' dilemma. All countries discriminate, but in equilibrium internationally mobile portfolio capital evades taxation successfully. In contrast, if all governments did not discriminate, tax competition leads to less tax evasion.

This paper explores the outcome of an international environmental agreement when the governments are elected by their citizens. It also considers a voter's incentives for supporting candidates who are less green than she is. In the extreme case of ''global'' pollution, the elected politicians pay no attention to the environment, and the resulting international agreement is totally ineffective. Moreover, if governments cannot negotiate and have to decide noncooperatively (and voters are aware of this), the elected politicians can be greener, ecological damage can be lower and the median voter's payoff can be higher than in the case with bargaining.

Minimally invasive surgical methods have been developed to provide patients the benefits of open operations with decreased pain and suffering. We have developed a system that allows the performance of cardiopulmonary bypass and myocardial protection with cardioplegic arrest without sternotomy or thoracotomy. In a canine model, we successfully used this system to anastomose the internal thoracic artery to the left anterior descending coronary artery in nine of 10 animals. The left internal thoracic artery was dissected from the chest wall, and the pericardium was opened with the use of thoracoscopic techniques and single lung ventilation. The heart was arrested with a cold blood cardioplegic solution delivered through the central lumen of a balloon occlusion catheter (Endoaortic Clamp; Heartport, Inc., Redwood City, Calif.) in the ascending aorta, and cardiopulmonary bypass was maintained with femorofemoral bypass. An operating microscope modified to allow introduction of the 3.5x magnification objective into the chest was positioned through a 10 mm port over the site of the anastomosis. The anastomosis was performed with modified surgical instruments introduced through additional 5 mm ports. In the cadaver model (n = 7) the internal thoracic artery was harvested and the pericardium opened by means of similar techniques. A precise arteriotomy was made with microvascular thoracoscopic instruments under the modified microscope on four cadavers. In three other cadavers we assessed the exposure provided by a small anterior incision (4 to 6 cm) over the fourth intercostal space. This anterior port can assist in dissection of the distal internal thoracic artery and provides direct access to the left anterior descending, circumflex, and posterior descending arteries. We have demonstrated the potential feasibility of grafting the internal thoracic artery to coronary arteries with the heart arrested and protected, without a major thoracotomy or sternotomy.

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