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This study explores the respective out‐of‐sample exchange rate forecasting abilities of five macroeconomic fundamental models in comparison to a naïve random walk model for Japan during the post‐Bretton Woods era. To assess the influence of major economic changes, we estimate both linear and nonlinear models for all the macroeconomic fundamentals. Overall, most structural exchange rate models outperform a naïve random walk model in terms of forecasting accuracy in the short horizon. When the fundamentals are only linearly modelled, the forecasting ability of the Taylor rule is generally superior to other fundamental models. When the fundamentals are nonlinearly specified, the predictability of some other models rises dramatically to match that of the Taylor rule models in short and/or long horizons. Of importance, we determine that the yen/dollar exchange rate forecasting performance effectively improves in several fundamental models when influential economic changes are incorporated.

Objective: Since virus infections in AIDS patients are mostly inevitable and as they frequently cause disease deterioration and therapeutic failures, a comprehensive investigation was made of the influence of the coinfections of 9 well-known viruses on disease progression in patients infected with human immunodeficiency virus type 1 (HIV). Methods: A cross-sectional study of 62 HIV-positive patients was conducted to correlate the prevalence rates for the 9 viruses with the alanine aminotransferase (ALT) levels and CD4 cell counts of the patients. Results: The rates of HIV-positive patients infected with the 9 viruses are significantly higher than those of the control groups. Furthermore, almost one third of the patients in the studied group was coinfected with transfusion-transmitted virus (TTV) and manifested significantly higher ALT levels (p = 0.020), and these were raised further if coinfection with TTV and human hepatitis C virus had occurred (p = 0.010). By analyzing CD4 cell counts, the only significant effect on AIDS progression which could be detected was coinfection with human herpesvirus 8. Conclusion: This result confirmed that immune-suppressed persons are more vulnerable to common virus infections. Unlike hepatitis B or C virus, TTV seems to accelerate the progression of chronic hepatitis in HIV-infected patients.