5,194 research outputs found
Universal magneto-orbital ordering in the divalent -site quadruple perovskite manganites MnO ( = Ca, Sr, Cd, and Pb)
Through analysis of variable temperature neutron powder diffraction data, we
present solutions for the magnetic structures of SrMnO,
CdMnO, and PbMnO in all long-range ordered phases. The
three compounds were found to have magnetic structures analogous to that
reported for CaMnO. They all feature a higher temperature lock-in
phase with \emph{commensurate} magneto-orbital coupling, and a delocked,
multi-\textbf{k} magnetic ground state where \emph{incommensurate}
magneto-orbital coupling gives rise to a constant-moment magnetic helix with
modulated spin helicity. CdMnO represents a special case in which
the orbital modulation is commensurate with the crystal lattice and involves
stacking of fully and partially polarized orbital states. Our results provide a
robust confirmation of the phenomenological model for magneto-orbital coupling
previously presented for CaMnO. Furthermore, we show that the model
is universal to the quadruple perovskite manganites synthesised to
date, and that it is tunable by selection of the -site ionic radius
Malignant melanoma of the conjunctiva: a case report with examination of KIT and PDGFRA
Although many clinicopathological studies of malignant melanoma of the conjunctiva have been reported, there have been no studies of the expression and gene mutations of KIT and PDGFRA in melanoma of the conjunctiva. A 69-year-old Japanese woman consulted our hospital because of black mass (0.7 × 0.7 × 0.6 cm) in the conjunctiva. A biopsy was taken. The biopsy showed malignant epithelioid cells with melanin deposition. Immunohistochemically, the tumor was positive for S100 protein, HMB45, p53, Ki-67 (labeling=30%), KIT and PDGFRA. The tumor was negative for pancytokeratins (AE1/3 and CAM5.2). A genetic analysis using PCR-direct sequencing revealed no mutations of KIT gene (exons 9, 11, 13, and 17) and PDGFRA gene (exons 12 and 18). The pathological diagnosis was conjunctival melanoma. Despite chemotherapy, the patient developed multiple metastases of melanoma, and died of melanoma 7 years after the biopsy. In conclusion, the author reported a case of melanoma of conjunctive expressing KIT and PDGFRA proteins without gene mutations of KIT and PDGFRA
Numerical and experimental verification of a theoretical model of ripple formation in ice growth under supercooled water film flow
Little is known about morphological instability of a solidification front
during the crystal growth of a thin film of flowing supercooled liquid with a
free surface: for example, the ring-like ripples on the surface of icicles. The
length scale of the ripples is nearly 1 cm. Two theoretical models for the
ripple formation mechanism have been proposed. However, these models lead to
quite different results because of differences in the boundary conditions at
the solid-liquid interface and liquid-air surface. The validity of the
assumption used in the two models is numerically investigated and some of the
theoretical predictions are compared with experiments.Comment: 30 pages, 9 figure
Distribution of dust clouds around the central engine of NGC 1068
We studied the distribution of dust clouds around the central engine of NGC
1068 based on shifted-and-added 8.8 - 12.3 micron (MIR) multi-filter images and
3.0 - 3.9 micron (L-band) spectra obtained with the Subaru Telescope. In a
region of 100 pc (1.4") around the central peak, we successfully constructed
maps of color temperatures and emissivities of the MIR and L-band continua as
well as the 9.7 micron and 3.4 micron dust features with spatial resolutions of
26 pc (0.37") in the MIR and 22 pc (0.3") in the L-band. Our main results are:
1) color temperature of the MIR continuum scatters around the thermal
equilibrium temperature with the central engine as the heat source while that
of the L-band continuum is higher and independent upon distance from the
central engine; 2) the peak of the 9.7 micron silicate absorption feature is
shifted to a longer wavelength at some locations; 3) the ratio of the optical
depths of the dust features is different from the Galactic values and show
complicated spatial distribution; and 4) there is a pie shaped warm dust cloud
as an enhancement in the emissivity of the MIR continuum extending about 50 pc
to the north from the central engine. We speculate that material falls into the
central engine through this cloud.Comment: 26 pages, 9 figures. Accepted for publication on Ap
Summary of the 13th IACHEC Meeting
We summarize the outcome of the 13th meeting of the International
Astronomical Consortium for High Energy Calibration (IACHEC), held at Tenuta
dei Ciclamini (Avigliano Umbro, Italy) in April 2018. Fifty-one scientists
directly involved in the calibration of operational and future high-energy
missions gathered during 3.5 days to discuss the current status of the X-ray
payload inter-calibration and possible approaches to improve it. This summary
consists of reports from the various working groups with topics ranging from
the identification and characterization of standard calibration sources,
multi-observatory cross-calibration campaigns, appropriate and new statistical
techniques, calibration of instruments and characterization of background, and
communication and preservation of knowledge and results for the benefit of the
astronomical community.Comment: 12 page
H Emission Nebulosity Associated with KH 15D
An H emission filament is found in close proximity to the unique object
KH 15D using the adaptive optics system of the Subaru Telescope. The morphology
of the filament, the presence of spectroscopic outflow signatures observed by
Hamilton et al., and the detection of extended H emission from KH 15D by
Deming, Charbonneau, & Harrington suggest that this filament arises from
shocked H in an outflow. The filament extends about 15" to the north of KH
15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres
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