Early-type Host Galaxies of Type Ia Supernovae. I. Evidence for Downsizing

Type Ia supernova (SN Ia) cosmology provides the most direct evidence for the presence of dark energy. This result is based on the assumption that the look-back time evolution of SN Ia luminosity, after light-curve corrections, would be negligible. Recent studies show, however, that the Hubble residual (HR) of SN Ia is correlated with the mass and morphology of host galaxies, implying the possible dependence of SN Ia luminosity on host galaxy properties. In order to investigate this more directly, we have initiated spectroscopic survey for the early-type host galaxies, for which population age and metallicity can be more reliably determined from the absorption lines. As the first paper of the series, here we present the results from high signal-to-noise ratio (>100 per pixel) spectra for 27 nearby host galaxies in the southern hemisphere. For the first time in host galaxy studies, we find a significant (~3.9sigma) correlation between host galaxy mass (velocity dispersion) and population age, which is consistent with the "downsizing" trend among non-host early-type galaxies. This result is rather insensitive to the choice of population synthesis models. Since we find no correlation with metallicity, our result suggests that stellar population age is mainly responsible for the relation between host mass and HR. If confirmed, this would imply that the luminosity evolution plays a major role in the systematic uncertainties of SN Ia cosmology.Comment: Accepted for publication in ApJ

Heisenberg-picture approach to the exact quantum motion of a time-dependent forced harmonic oscillator

In the Heisenberg picture, the generalized invariant and exact quantum motions are found for a time-dependent forced harmonic oscillator. We find the eigenstate and the coherent state of the invariant and show that the dispersions of these quantum states do not depend on the external force. Our formalism is applied to several interesting cases.Comment: 15 pages, two eps files, to appear in Phys. Rev. A 53 (6) (1996

Markers and meaning of authenticity : narratives of Mosuo, Bhutan and Harris Tweed weavers

This research aimed to discover whether weavers could identify markers of authenticity of their own community-based and culturally bound hand-woven textiles. If so, how do they do it? What is the nature and meaning of these markers? Three case studies were selected that represented communities making such textiles at different levels of institutionalisation. The first case focused on the non-insitutionalised Mosuo hand-woven textiles, a minority group in southwest China. This is contrasted with the fully legally institutionalised and branded Harris Tweed of Scotland. In between these two extremes, a study on Bhutanese kiras where the design and weaving of textiles are culturally institutionalised without a legal framework or a commercial brand. A pilot study phase informed the use of an ethnographic approach to field research conducted at the three sites employing a diverse range of methods including face-to-face interviews based on semi-structured questionnaires. When opportunities arose, indirect methods were included such as unobtrusive observations, examinations of exemplar textiles, and review through 'thick' descriptions in reflective journals. Data from these qualitative studies were distilled and confirmed through quantitative follow-up methods. The results indicated that for the Mosuo weavers, it is her experience of being a Mosuo weaver and the spirit in which the textiles are woven that determined authenticity. For culturally structured societies such as in Bhutan, authenticity was dependent on the contexts in which the kira was meant to be worn, reflected in turn through the physical characteristics of the kira. The markers of authenticity of Harris Tweed relied on objective characteristics including the geographical site where the cloth is produced. Central to the experience of the weaver in all three studies was the pride in weaving the textile, a finding which identifies this element as a common marker of its authenticity

A Test of the Adaptive Market Hypothesis using a Time-Varying AR Model in Japan

This study examines the adaptive market hypothesis (AMH) in Japanese stock markets (TOPIX and TSE2). In particular, we measure the degree of market efficiency by using a time-varying model approach. The empirical results show that (1) the degree of market efficiency changes over time in the two markets, (2) the level of market efficiency of the TSE2 is lower than that of the TOPIX in most periods, and (3) the market efficiency of the TOPIX has evolved, but that of the TSE2 has not. We conclude that the results support the AMH for the more qualified stock market in Japan.Comment: 10 pages, 2 figure, 2 table

Effect of Outlier Removal from Temporal ASF Corrections on Multichain Loran Positioning Accuracy

The widely used global navigation satellite systems (GNSSs) are vulnerable to radio frequency interference (RFI). Long-range navigation (Loran), a terrestrial navigation system, can compensate for this weakness; however, it suffers from low positioning accuracy, and studies are under way to improve its positioning performance. One such study has proposed the multichain Loran positioning method that uses the signals of transmitting stations belonging to different chains. Although the multichain Loran positioning performance is superior to the performance of conventional methods, the additional secondary factor (ASF) can still degrade its positioning accuracy. To mitigate the effects of temporal ASF, which is one of the ASF components, it is necessary to obtain temporal correction data from a nearby reference station at a known location. In this study, an experiment is performed to verify the effect of removing the outliers in the temporal correction data on the multichain Loran positioning accuracy.Comment: Submitted to ICCAS 202