Sequential Internet Auctions with Different Ending Rules

Two ending rules, a soft close and a hard close, exist in Internet auctions. In hard close auctions, each auction ends with a fixed deadline determined by a seller. In soft close auctions, the end time automatically extends if at least one bid is submitted in the last few minutes, so each buyer has an opportunity to reply to other buyers' bids. The reserve prices set by the seller in hard close auctions are higher than the reserve prices in soft close auctions. The result is consistent with data of DS Lite auctions in Yahoo! Japan.

Market research and complementary advertising under asymmetric information

We consider whether market research can always increase a seller's sales under bilateral asymmetric information. If a monopoly seller provides a high quality object, market research cannot increase sales even when the cost is sufficiently low. A low quality seller, on the other hand, can likely benefit from market research. However, this research has shown that market research alone does not improve sales and that advertising complements market research. Thus the high quality seller can increase sales by using both methods. The availability of advertising and market research to both types of seller results in disappearance of information asymmetry and efficient trade.

Spectral Variation of the Seyfert 1 Galaxy MCG-6-30-15 observed with Suzaku

We have investigated spectral variation of the Seyfert 1 galaxy MCG-6-30-15 observed with Suzaku in January 2006 for three separate periods spreading over fourteen days. We found that the time-averaged continuum energy spectrum between 1 keV and 40 keV can be approximated with a spectral model composed of the direct power-law component, its reflection component, two warm absorbers with different ionization states, and neutral absorption. We have taken two approaches to study its spectral variation at various timescales: The first approach is to make intensity-sliced spectra and study correlation between the intensity and spectral shape. The second approach is to study spectral changes between the intervals when the source flux is above ("bright state") and below ("faint state") the average for fixed time-intervals. In both approaches, we found a clear correlation between the intensity in the 6 -- 10 keV band and the spectral ratio of 0.5 -- 3.0 keV/6.0-- 10 keV. Such a spectral variation requires change of the apparent slope of the direct component, whereas the shape and intensity of the reflection component being invariable. The observed apparent spectral change is explained by variation of the ionization degree of one of the two warm absorbers due to intrinsic source luminosity variation. Current results suggest that the warm absorber has a critical role to explain the observed continuum spectral shape and variation of MCG-6-30-15, which is essential to constrain parameters of the putatively broadened iron line emission feature.Comment: 11 pages, accepted for publication in PAS

Clinical characteristics and outcomes of heart failure with preserved ejection fraction: Lessons from epidemiological studies

SummaryRecent epidemiological studies have demonstrated that nearly half of all patients with heart failure (HF) have preserved left ventricular ejection fraction (HFPEF). Compared to those with reduced EF, patients with HFPEF are older, more likely to be women, less likely to have coronary artery disease, and more likely to have hypertension and atrial fibrillation. Patients with HFPEF receive different pharmacological as well as nonpharmacological treatments from those with reduced EF. Morbidity and mortality in patients with HFPEF are largely similar to those with reduced EF. Although much information has recently been obtained about the clinical characteristics, medications, and outcomes of HFPEF by large-scale clinical and epidemiological studies, effective management strategies need to be established for this type of HF

Environmental Factors and Seasonal Influenza Onset in Okayama City, Japan: Case-Crossover Study

Seasonal influenza infection is a major challenge in public health. The term "seasonal influenza" refers to the typical increase in the number of influenza patients in the winter season in temperature zones. However, it is not clear how environmental factors within a single flu season affect influenza infection in a human population. Therefore, we evaluated the effects of temperature and humidity in the 2006-7 flu season on the onset of seasonal influenza using a case-crossover study. We targeted patients who attended one pediatric clinic in Okayama city, Japan and who were diagnosed as being infected with the seasonal influenza virus. Using 2 references (time-stratified and symmetric bidirectional design), we estimated the effects of average temperature and relative humidity from the onset day (lag0) to 10 days before (lag10). The total number of subjects was 419, and their onset days ranged from 26 December 2006 to 30 April 2007. While the onset was significantly associated with lower temperature, relative humidity was not related. In particular, temperatures before the 3-day incubation period had higher-magnitude odds ratios. For example, the odds ratio and 95% confidence interval for average temperature at time lag 8 was 1.12 (1.08-1.17) per 1.0℃ decrease. Low environmental temperature significantly increased the risk of seasonal influenza onset within the 2006-7 winter season