258 research outputs found
Observations of High Energy Cosmic-Ray Electrons from 30 GeV to 3 TeV with Emulsion Chambers
We have performed a series of cosmic-ray electron observations using the
balloon-borne emulsion chambers since 1968. While we previously reported the
results from subsets of the exposures, the final results of the total exposures
up to 2001 are presented here. Our successive experiments have yielded the
total exposure of 8.19 m^2 sr day at the altitudes of 4.0 - 9.4 g/cm^2. The
performance of the emulsion chambers was examined by accelerator beam tests and
Monte-Carlo simulations, and the on-board calibrations were carried out by
using the flight data. In this work we present the cosmic-ray electron spectrum
in the energy range from 30 GeV to 3 TeV at the top of the atmosphere, which is
well represented by a power-law function with an index of -3.28+-0.10. The
observed data can be also interpreted in terms of diffusive propagation models.
The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of
cosmic-ray electron sources at distances within ~1 kpc and times within ~1x10^5
yr ago.Comment: 38 pages, 10 figures, 3 tables, Accepted for publication in Ap
Residual mitral regurgitation after repair for posterior leaflet prolapse- Importance of preoperative anterior leaflet tethering
Background
Carpentier's techniques for degenerative posterior mitral leaflet prolapse have been established with excellent long‐term results reported. However, residual mitral regurgitation (
MR
) occasionally occurs even after a straightforward repair, though the involved mechanisms are not fully understood. We sought to identify specific preoperative echocardiographic findings associated with residual
MR
after a posterior mitral leaflet repair.
Methods and Results
We retrospectively studied 117 consecutive patients who underwent a primary mitral valve repair for isolated posterior mitral leaflet prolapse including a preoperative 3‐dimensional transesophageal echocardiography examination. Twelve had residual
MR
after the initial repair, of whom 7 required a corrective second pump run, 4 underwent conversion to mitral valve replacement, and 1 developed moderate
MR
within 1 month. Their preoperative parameters were compared with those of 105 patients who had an uneventful mitral valve repair. There were no hospital deaths. Multivariate analysis identified preoperative anterior mitral leaflet tethering angle as a significant predictor for residual
MR
(odds ratio, 6.82; 95% confidence interval, 1.8–33.8;
P
=0.0049). Receiver operator characteristics curve analysis revealed a cut‐off value of 24.3° (area under the curve, 0.77), indicating that anterior mitral leaflet angle predicts residual
MR
. In multivariate regression analysis, smaller anteroposterior mitral annular diameter (
P
<0.001) and lower left ventricular ejection fraction (
P
=0.002) were significantly associated with higher anterior mitral leaflet angle, whereas left ventricular and left atrial dimension had no significant correlation.
Conclusions
Anterior mitral leaflet tethering in cases of posterior mitral leaflet prolapse has an adverse impact on early results following mitral valve repair. The findings of preoperative 3‐dimensional transesophageal echocardiography are important for consideration of a careful surgical strategy.
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Development of an Operating Strategy for On-Demand Earth Observation Missions of the Diwata-2 Microsatellite
Diwata-2 is the Philippines’ 2nd microsatellite developed by Tohoku University, Hokkaido University, University of the Philippines, and the Philippine Department of Science and Technology. Its primary purpose is gathering remote sensing data through imaging areas of interest for the Philippines. This paper presents the study of Diwata-2’s initial Earth observation pointing performance, investigation of its Attitude Determination and Control System, the tuning of its Star Tracker sensor parameters, the in-flight target pointing calibration, and the sequential scheduling of its components forming an operation strategy for an effective on-demand earth observation mission. This operation strategy has managed to improve the satellite’s pointing performance from the initial 2.88°±2.06° RMS pointing error to having an accuracy of 0.204°±0.12° RMS for its High Precision Telescope payload. This strategy has been implemented to the university-built microsatellite for over 400 successful Earth observation missions and has covered about 82.8% of the Philippine’s land area with its Spaceborne Multispectral Imager payload
Pulmonary Fibrosis in Response to Environmental Cues and Molecular Targets Involved in Its Pathogenesis
Chronic lung injury resulting from a variety of different causes is frequently
associated with the develop ment of pulmonary fibrosis in humans. Although the etiology of
pulmonary fibrosis is generally unknown, several sources of evidence support the
hypothesis that a number of environmental and occupational agents play an etiologic role
in the pathogenesis of this disease. The agents discussed in this review include
beryllium, nylon flock, textile printing aerosols, polyvinyl chloride and
didecyldimethylammonium chloride. The authors also describe a variety of animal models,
including genetically modified mice, in order to investigate the molecular mechanism of
pulmonary fibrosis, focusing on chemokine receptors, regulatory T cells and transforming
growth factor-β and bone morphogenetic protein signaling. Overall, we propose the concept
of toxicological pulmonary fibrosis as a lung disease induced in response to environmental
cues
現像温度および時間のマンモフイルム特性に与える影響
The influence for developing temperature and processing time within film processing conditions was investigated using four mammographic films, Konica New CM, Fuji UM-MA HC, Kodak Min-R M and Kodak EB/RA (for rapid system). And Fuji UR-2, a double-emulsion film, was used as a control. Those sensitometric strips exposed by a sensitometer were processed in the different combinations of developing temperatures ranging from 28 to 36℃, processing times from 45 to 210 sec. Average gradient, relative speed and base plus fog obtained from the measured film characteristic
curves were evaluated for the different developing temperatures and times. Fuji UR-2 was scarcely affected and mammographic films were greatly affected in the different combinations without an increase in base plus fog except EB/RA. In New CM, UM-MA HC and Min-R M, the average gradients and the relative speeds increased as the developing temperature was higher and the developing time was longer, but the increases were limit on the combination of 36℃ and 210 sec in New CM and UM-MA HC. In EB/RA, the average gradients were almost constant and the relative speeds increased slightly like the double-emulsion film. These results suggested that it would be
possible to contribute to dose reduction and advancement of contrast in New CM, UM-MA HC and Min-R M by changing these processing parameters.フィルム処理条件において,現像温度と処理時間に対する影響を4種類のマンモグラフィ用フィルムKonica New CM, Fuji UM-MA HC,Kodak Min-R M,迅速処理用Kodak EB/RAについて調べた。そして,比較基準用として両面乳剤フィルムFuji UR-2を用いた。感光計で露光したフィルムを現像温度28~36℃,処理時間45~210秒で処理した。特性曲線から得られたフィルム特性(平均階調度,相対感度,カブリ濃度)を異なる現像温度,現像時間に対して評価した。UR-2はほとんど影響を受けず,マンモグラフィ用フィルムは,カブリ濃度が上昇することなく,現像条件の影響を大きく受けた。New CM, UM-MA HC,Min-R Mは現像温度の上昇,処理時間の延長に伴い,平均階調度と相対感度は増加した。しかし,New CM, UM-MA HCの36℃,210秒で増加は限度に達した。EB/RAの平均階調度は一定で,相対感度は両面乳剤フイルムと同
様にわずかな増加であった。これらの結果は,New CM, UM-MA HC, Min-R Mにおいて,処理条件を変化させることにより,被曝低減,コントラスト向上に貢献できる可能性を示唆していた
A Case of Periodontal Necrosis following Embolization of Maxillary Artery for Epistaxis
Embolization of the maxillary artery (MA) is a common treatment modality for refractory epistaxis. Tissue necrosis after embolization of the MA is a rare complication. Here, we reported the first case of the development of necrosis of soft tissue and alveolar bone in the periodontium after embolization. A 48-year-old man with poor oral hygiene and a heavy smoking habit was referred to our clinic due to intractable epistaxis. After treatment with anterior-posterior nasal packing (AP nasal packing), the epistaxis relapsed. Therefore, he underwent embolization of the MA. Although he did not experience epistaxis after embolization, periodontal necrosis developed gradually. The wound healed with necrotomy, administration of antibiotics and prostaglandin, and hyperbaric oxygen therapy. We speculated that the periodontal necrosis was provoked by reduction of blood supply due to embolization and AP nasal packing based on this preexisting morbid state in the periodontium. Poor condition of the oral cavity and smoking may increase the risk of periodontal necrosis after embolization
Superwind-Driven Intense H_2 Emission in NGC 6240
We have performed a long-slit K band spectroscopic observation of the
luminous infrared galaxy NGC 6240. The peak position of the H_2 v=1-0 S(1)
emission in the slit is located ~0.3" - 0.4" north of the southern nucleus. It
is almost the midpoint between the southern nucleus and the peak position of
the ^12CO J=1-0 emission. Based on the line-ratio analyses, we suggest the
excitation mechanism of H_2 is pure thermal at most positions. In the southern
region we find the following three velocity components in the H_2 emission: the
blueshifted shell component (~-250 km s^-1 with respect to V_sys) which is
recognized as a distinct C-shape distortion in the velocity field around the
southern nucleus, the high-velocity blueshifted ``wing'' component (~-1000 km
s^-1 with respect to V_sys), and the component indicating possible line
splitting of ~500 km s^-1. The latter two components are extended to the south
from the southern nucleus. We show that the kinematic properties of these three
components can be reproduced by expanding motion of a shell-like structure
around the southern nucleus. The offset peak position of the H_2 emission can
be understood if we assume that the shell expanding to the north interacts with
the extragalactic molecular gas. At the interface between the shell and the
molecular gas concentration the cloud-crushing mechanism proposed by Cowie et
al. (1981) may work efficiently, and the intense H_2 emission is thus expected
there. All these findings lead us to propose a model that the most H_2 emission
is attributed to the shock excitation driven by the superwind activity of the
southern nucleus.Comment: 33 pages, 9 figures, accepted for publication in PAS
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