21 research outputs found
Far-infrared dust properties in the Galaxy and the Magellanic Clouds
A recent data analysis of the far-infrared (FIR) map of the Galaxy and the
Magellanic Clouds has shown that there is a tight correlation between two FIR
colours: the 60 um-100 um and 100 um-140 um colours. This FIR colour relation
called ``main correlation'' can be interpreted as indicative of a sequence of
various interstellar radiation fields with a common FIR optical property of
grains. In this paper, we constrain the FIR optical properties of grains by
comparing the calculated FIR colours with the observational main correlation.
We show that neither of the ``standard'' grain species (i.e. astronomical
silicate and graphite grains) reproduces the main correlation. However, if the
emissivity index at ~ 100--200 um is changed to ~ 1--1.5 (not ~ 2 as the above
two species), the main correlation can be successfully explained. Thus, we
propose that the FIR emissivity index is ~ 1--1.5 for the dust in the Galaxy
and the Magellanic Clouds at ~ 100--200 um. We also consider the origin of the
minor correlation called ``sub-correlation'', which can be used to estimate the
Galactic star formation rate.Comment: 12 pages, 8 figures, accepted for publication in MNRA
The Far-Infrared Surveyor (FIS) for AKARI
The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the
AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and
uses two kinds of array detectors. The FIS arrays and optics are designed to
sweep the sky with high spatial resolution and redundancy. The actual scan
width is more than eight arcmin, and the pixel pitch is matches the diffraction
limit of the telescope. Derived point spread functions (PSFs) from observations
of asteroids are similar to the optical model. Significant excesses, however,
are clearly seen around tails of the PSFs, whose contributions are about 30% of
the total power. All FIS functions are operating well in orbit, and its
performance meets the laboratory characterizations, except for the two longer
wavelength bands, which are not performing as well as characterized.
Furthermore, the FIS has a spectroscopic capability using a Fourier transform
spectrometer (FTS). Because the FTS takes advantage of the optics and detectors
of the photometer, it can simultaneously make a spectral map. This paper
summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the
AKARI special issue of the Publications of the Astronomical Society of Japa
Optimal Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Patients With Multivessel Disease
BACKGROUND: Intravascular ultrasound (IVUS) was only rarely used in landmark trials comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel disease. OBJECTIVES: The authors aimed to evaluate clinical outcomes after optimal IVUS-guided PCI in patients undergoing multivessel PCI. METHODS: The OPTIVUS (OPTimal IntraVascular UltraSound)-Complex PCI study multivessel cohort was a prospective multicenter single-arm study enrolling 1, 021 patients undergoing multivessel PCI, including left anterior descending coronary artery using IVUS, aiming to meet the prespecified criteria (OPTIVUS criteria: minimum stent area > distal reference lumen area [stent length ≥28mm], and minimum stent area >0.8 × average reference lumen area [stent length <28mm]) for optimal stent expansion. The primary endpoint was major adverse cardiac and cerebrovascular events (MACCE) (death/myocardial infarction/stroke/any coronary revascularization). The predefined performance goals were derived from the CREDO-Kyoto (Coronary REvascularization Demonstrating Outcome study in Kyoto) PCI/CABG registry cohort-2 fulfilling the inclusion criteria in this study. RESULTS: In this study, 40.1% of the patients met OPTIVUS criteria in all stented lesions. The cumulative 1-year incidence of the primary endpoint was 10.3% (95% CI: 8.4%-12.2%), which was significantly lower than the predefined PCI performance goal of 27.5% (P < 0.001), and which was numerically lower than the predefined CABG performance goal of 13.8%. The cumulative 1-year incidence of the primary endpoint was not significantly different regardless of meeting or not meeting OPTIVUS criteria. CONCLUSIONS: Contemporary PCI practice conducted in the OPTIVUS-Complex PCI study multivessel cohort was associated with a significantly lower MACCE rate than the predefined PCI performance goal, and with a numerically lower MACCE rate than the predefined CABG performance goal at 1 year