Optimal Timing in Trading Japanese Equity Mutual Funds: Theory and Evidence

This paper provides both theoretical and empirical analyses of market participants' optimal decision-making in trading Japanese equity mutual funds. First, we build an intertemporal decision-making model under uncertainty in the presence of transaction costs. This setting enables us to shed light on the investors' option to delay investment. A comparative analysis shows that an increase in uncertainty over the expected rate of return on mutual funds has a negative impact not only on market participants' buying behavior but also on their selling behavior. In addition, a several percent increase in front-end loads and redemption fees is likely to change the optimal holding ratio of mutual funds in investors' portfolios, by up to 10 percent. Second, we empirically examine the theoretical implications using daily transaction data of selected equity mutual funds in Japan. By estimating a panel data model, we conclude that for the sample period, from August 2000 to July 2001, investment behavior has been rational in light of our theoretical model. Our results suggest that investors are likely to rationally postpone their purchases of equity mutual funds under the present circumstances of low expected returns, high degree of uncertainty, and high trading costs.

Progression of coronary atherosclerosis: Is coronary spasm related to progression?

AbstractA total of 239 patients undergoing serial coronary angiography with a concomitant ergonovine provocation test were studied between July 1974 and June 1987. The progression of coronary artery disease was evaluated in relation to risk factors, especially coronary artery spasm. Patients were classified into three groups: 1) new myocardial infarction group (39 patients); 2) progression without infarction group (90 patients); and 3) nonprogression group (110 patients).To assess how risk factors and coronary spasm are related to the occurrence of new myocardial infarction and progression without infarction, 11 variables in the three groups were examined: age, gender, the time interval between the studies, fasting blood sugar, systolic blood pressure, diastolic blood pressure, smoking, serum cholesterol, triglyceride, uric acid and a positive response to the ergonovine provocation test. Multiple regression analysis selected three independent predictors of progression without infarction: cholesterol (p < 0.01), systolic blood pressure (p < 0.05) and a positive response to the ergonovine provocation test (p < 0.001). Multiple regression analysis also selected three independent predictors of the occurrence of new myocardial infarction: fasting blood sugar (p < 0.01), systolic blood pressure (p < 0.05) and a positive response to the ergonovine provocation test (p < 0.001). A positive response to the ergonovine provocation test was the strongest factor for occurrence of both new myocardial infarction and progression without infarction.To evaluate segmental arterial changes, 3,275 coronary artery segments were analyzed in the 239 patients. Both new myocardial infarction and progression without infarction frequently occurred in the proximal segments of the right coronary artery, the proximal and middle segments of the left anterior descending artery and the middle segments of the circumflex coronary artery. Although occurrence of both new myocardial infarction and progression without infarction were often evident in coronary artery segments with severe narrowing, >50% of new myocardial infarctions occurred in relation to segments narrowed <50%.The study strongly suggests that coronary spasticity may play a significant role in progression of coronary artery disease and that usual risk factors are closely related to the disease progression. The study also demonstrates that patients with myocardial infarction often show a “jump-up” phenomenon in which a minimal coronary stenosis progresses to total obstruction

Dynamic imaging of somatosensory cortical activity in the rat visualized by flavoprotein autofluorescence

We used autofluorescence of mitochondrial flavoproteins to image cortical neural activity in the rat. Green autofluorescence in blue light was examined in slices obtained from rat cerebral cortex. About half of the basal autofluorescence was modulated by the presence or absence of O2 or glucose in the medium. Repetitive electrical stimulation at 20 Hz for 1 s produced a localized fluorescence increase in the slices. The amplitude of the increase was 27 ± 2 % (mean ± s.d., n = 35). Tetrodotoxin or diphenyleneiodonium, an inhibitor of flavoproteins, blocked the autofluorescence responses. The autofluorescence responses were not observed in slices perfused with calcium-, glucose- or O2-free medium. In the primary somatosensory cortex of rats anaesthetized with urethane (1.5 g kg−1, i.p.), an activity-dependent increase in autofluorescence of 20 ± 4 % (n = 6) was observed after electrical cortical stimulation at 100 Hz for 1 s, and an increase of 2.6 ± 0.5 % (n = 33) after vibratory skin stimulation at 50 Hz for 1 s applied to the plantar hindpaw. These responses were large enough to allow visualization of the neural activity without having to average a number of trials. The distribution of the fluorescence responses after electrical or vibratory skin stimulation was comparable to that of the cortical field potentials in the same rats. The fluorescence responses were followed by an increase in arterial blood flow. The former were resistant to an inhibitor of nitric oxide synthase, while the latter was inhibited. Thus, activity-dependent changes in the autofluorescence of flavoproteins are useful for functional brain imaging in vivo