131 research outputs found
Structures and Magnetic Properties of Tm1-yYyMn1-xCoxO3
The structure and magnetic properties of Tm1−y Y y Mn1−x Co x O3 with 0 ≦ x ≦ 0.5 and 0 ≦ y ≦ 0.3 were investigated by X-ray diffraction, specific heat and magnetization measurements. Thulium manganite TmMnO3 prepared by solid-state synthesis at ambient pressure is hexagonal and antiferromagnetic with a Nèel temperature T N of 86 K. The substitution of Y for Tm in TmMnO3 does not greatly affect the fundamental hexagonal structure. The magnetization and specific heat measurement results for Tm1−y Y y MnO3 can be qualitatively explained in terms of the dilution effect of Tm by Y. On the other hand, the structure of TmMn1−x Co x O3 changes gradually from hexagonal to orthorhombic with the substitution of Co for Mn; hexagonal and orthorhombic phases coexist in samples for x ≦ 0.3 whereas TmMn0.6Co0.4O3 is almost a single orthorhombic phase. The magnetization of TmMn0.6Co0.4O3 in a field of 250 Oe increases rapidly at about 60K with decreasing temperature. The difference between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations increases remarkably at about 60 K. Moreover, the temperature dependences of the ZFC and the FC magnetizations exhibit peaks at about 40 and 30K, respectively. Thus, TmMn1−x Co x O3 exhibits complex magnetic properties
Improvement of shipborne sky radiometer and its demonstration aboard the Antarctic research vessel Shirase
動揺する船上においても太陽直達光を観測できるように,船舶用スカイラジオメータの太陽追尾性能を改良した.改良点は,太陽追尾精度の向上,測器視野角の拡大,太陽追尾速度の迅速化および測定手法の改良である.改良後の装置を用いて,第51次および第52次日本南極地域観測隊の本観測時に,南極観測船「しらせ」船上において太陽直達光および天空輝度分布を測定し,動揺した船上での直達光観測に成功した.直達光から算出された波長500nm における大気エアロゾルの光学的厚さは0.01-0.34であり,東南アジアおよび春季の西太平洋上で高い値を示した.オングストローム指数は-0.06~2.00の範囲であり,東南アジアおよびシドニー付近で最大を示した.今後,船舶用スカイラジオメータが,海洋上の大気エアロゾルに関する知見を深めると期待される.The sun-tracking performance of a shipborne sky radiometer was improved to attain accurate aerosol optical thickness (AOT) from direct solar measurements on a pitching and rolling vessel. Improvements were made in the accuracy of sun-pointing measurements, field-of-view expansion, sun-tracking speed, and measurement method. Radiometric measurements of direct solar and sky brightness distribution were performed using the shipborne sky radiometer onboard the Antarctic research vessel (R/V) Shirase during JARE-51 (2009-2010) and JARE-52 (2010-2011). The temporal variation of signal intensity measured by the radiometer under cloudless conditions was smooth, demonstrating that the radiometer could measure direct sunlight onboard the R/V. AOT at 500 nm ranged from 0.01 to 0.34, and values over Southeast Asia and over the western Pacific Ocean in spring were higher than those over other regions. The Angstrom exponent ranged from -0.06 to 2.00, and values over Southeast Asia and off the coast near Sydney were the highest. The improved shipborne sky radiometer will contribute to a good understanding of the nature of aerosols over the ocean
Typical performance of low-density parity-check codes over general symmetric channels
Typical performance of low-density parity-check (LDPC) codes over a general
binary-input output-symmetric memoryless channel is investigated using methods
of statistical mechanics. Theoretical framework for dealing with general
symmetric channels is provided, based on which Gallager and MacKay-Neal codes
are studied as examples of LDPC codes. It has been shown that the basic
properties of these codes known for particular channels, including the property
to potentially saturate Shannon's limit, hold for general symmetric channels.
The binary-input additive-white-Gaussian-noise channel and the binary-input
Laplace channel are considered as specific channel noise models.Comment: 10 pages, 4 figures, RevTeX4; an error in reference correcte
Ship-borne measurement of maritime aerosol with new sky radiometer
第3回極域科学シンポジウム/第35回極域気水圏シンポジウム 11月30日(金) 国立国語研究所 2階ロビ
Hemorrhage from varices in hepaticojejunostomy in the fifth and tenth year after surgery for hepatic hilar bile duct cancer: a case report
We report a case of a 64-year-old female patient who underwent a right lobectomy of the liver (including total resection of the caudate lobe), dissection of the group 2 lymph nodes, left hepaticojejunostomy (Roux-en-Y fashion), and reconstruction of the portal vein (end-to-end anastomosis between the main portal vein and the left portal branch) for treatment of hepatic hilar bile duct cancer in 1996. In 2001, the anastomotic site of the hepaticojejunostomy was dissected and re-anastomosed due to gastrointestinal bleeding caused by variceal rupture in the jejunal loop. In 2006, splenectomy was performed for recurrence of gastrointestinal bleeding due to another variceal rupture in the jejunal loop. Portal venography performed perioperatively showed a decrease in portal blood flow into the liver via the jejunal varices and an increase in portal blood flow into the liver via the left gastric vein. She had two jejunal variceal ruptures at five-year intervals after extrahepatic portal obstruction and underwent successful treatments
Preliminary results of proton radiotherapy for pediatric rhabdomyosarcoma: a multi-institutional study in Japan
To evaluate preliminary results of proton radiotherapy (PRT) for pediatric patients with rhabdomyosarcoma (RMS). From 1987 to 2014, PRT was conducted as initial radiotherapy in 55 patients (35 males, 20 females, median age 5 years, range 0–19) with RMS at four institutes in Japan. Thirty‐one, 18, and six patients had embryonal, alveolar, and other RMS, respectively. One, 11, 37, and six patients were in IRSG groups I, II, III, and IV, respectively, and the COG risk group was low, intermediate, and high for nine, 39, and seven patients, respectively. The irradiation dose was 36–60 GyE (median: 50.4 GyE). The median follow‐up period was 24.5 months (range: 1.5–320.3). The 1‐ and 2‐year overall survival rates were 91.9% (95% CI: 84.3–99.5%) and 84.8% (95% CI 75.2–94.3%), respectively, and these rates were 100% and 100%, 97.1% and 90.1%, and 57.1% and 42.9% for COG low‐, intermediate‐, and high‐risk groups, respectively. There were 153 adverse events of Grade ≥3, including 141 hematologic toxicities in 48 patients (87%) and 12 radiation‐induced toxicities in nine patients (16%). Proton‐specific toxicity was not observed. PRT has the same treatment effect as photon radiotherapy with tolerable acute radiation‐induced toxicity
A Shock-Induced Pair of Superbubbles in the High-Redshift Powerful Radio Galaxy MRC 0406-244
We present new optical spectroscopy of the high-redshift powerful radio
galaxy MRC 0406244 at redshift of 2.429. We find that the two extensions
toward NW and SE probed in the rest-frame ultraviolet image are heated mainly
by the nonthermal continuum of the active galactic nucleus. However, each
extension shows a shell-like morphology, suggesting that they are a pair of
superbubbles induced by the superwind activity rather than by the interaction
between the radio jet and the ambient gas clouds. If this is the case, the
intense starburst responsible for the formation of superbubbles could occur
yr ago. On the other hand, the age of the radio jets may
be of the order of yr, being much shorter than the starburst age.
Therefore, the two events, i.e., the starburst and the radio-jet activities,
are independent phenomena. However, their directions of the expanding motions
could be governed by the rotational motion of the gaseous component in the host
galaxy. This idea appears to explain the alignment effect of MRC 0406244.Comment: 4 pages (emulateapj.sty), Fig. 1 (jpeg) + Fig.2 (eps). Accepted for
publications in ApJ (Letters
The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
We report an extensive search for Lyman-alpha emitters (LAEs) at z=6.5 in the
Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified
eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at
z=6.5. Based on this spectroscopic sample of 17, complemented by a photometric
sample of 58 LAEs, we have derived a more accurate Lyman-alpha luminosity
function of LAEs at z=6.5, which reveals an apparent deficit at the bright end
of ~0.75 mag fainter L*, compared with that observed at z=5.7. The difference
in the LAE luminosity functions between z=5.7 and 6.5 is significant at the
3-sigma level, which is reduced to 2-sigma when cosmic variance is taken into
account. This result may imply that the reionization of the universe has not
been completed at z=6.5. We found that the spatial distribution of LAEs at
z=6.5 was homogeneous over the field. We discuss the implications of these
results for the reionization of the universe.Comment: To appear in APJ vol.648. Only minor corrections have been made.
Black&White version is available at
http://zone.mtk.nao.ac.jp/~kashik/sdf/z6p5lae/paper/sdf_z6p5lae_bw.pd
Long-term follow-up after proton beam therapy for pediatric tumors: a Japanese national survey
Proton beam therapy (PBT) is a potential new alternative to treatment with photon radiotherapy that may reduce the risk of late toxicity and secondary cancer, especially for pediatric tumors. The goal of this study was to evaluate the long-term benefits of PBT in cancer survivors. A retrospective observational study of pediatric patients who received PBT was performed at four institutions in Japan. Of 343 patients, 62 were followed up for 5 or more years. These patients included 40 males and 22 females, and had a median age of 10 years (range: 0–19 years) at the time of treatment. The irradiation dose ranged from 10.8 to 81.2 GyE (median: 50.4 GyE). The median follow-up period was 8.1 years (5.0–31.2 years). The 5-, 10- and 20-year rates for grade 2 or higher late toxicities were 18%, 35% and 45%, respectively, and those for grade 3 or higher late toxicities were 6%, 17% and 17% respectively. Univariate analysis showed that the irradiated site (head and neck, brain) was significantly associated with late toxicities. No malignant secondary tumors occurred within the irradiated field. The 10- and 20-year cumulative rates for all secondary tumors, malignant secondary tumors, and malignant nonhematologic secondary tumors were 8% and 16%, 5% and 13%, and 3% and 11%, respectively. Our data indicate that PBT has the potential to reduce the risk of late mortality and secondary malignancy. Longer follow-up is needed to confirm the benefits of PBT for pediatric tumors
Clustering of Lyman Break Galaxies at z=4 and 5 in The Subaru Deep Field: Luminosity Dependence of The Correlation Function Slope
We explored the clustering properties of Lyman Break Galaxies (LBGs) at z=4
and 5 with an angular two-point correlation function on the basis of the very
deep and wide Subaru Deep Field data. We found an apparent dependence of the
correlation function slope on UV luminosity for LBGs at both z=4 and 5. More
luminous LBGs have a steeper correlation function. To compare these
observational results, we constructed numerical mock LBG catalogs based on a
semianalytic model of hierarchical clustering combined with high-resolution
N-body simulation, carefully mimicking the observational selection effects. The
luminosity functions for LBGs predicted by this mock catalog were found to be
almost consistent with the observation. Moreover, the overall correlation
functions of LBGs were reproduced reasonably well. The observed dependence of
the clustering on UV luminosity was not reproduced by the model, unless
subsamples of distinct halo mass were considered. That is, LBGs belonging to
more massive dark haloes had steeper and larger-amplitude correlation
functions. With this model, we found that LBG multiplicity in massive dark
halos amplifies the clustering strength at small scales, which steepens the
slope of the correlation function. The hierarchical clustering model could
therefore be reconciled with the observed luminosity-dependence of the angular
correlation function, if there is a tight correlation between UV luminosity and
halo mass. Our finding that the slope of the correlation function depends on
luminosity could be an indication that massive dark halos hosted multiple
bright LBGs (abridged).Comment: 16 pages, 17 figures, Accepted for publication in ApJ, Full
resolution version is available at
http://zone.mtk.nao.ac.jp/~kashik/sdf/acf/sdf_lbgacf.pd
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