6,295 research outputs found
Spin-Wave Spectrum in `Single-Domain' Magnetic Ground State of Triangular Lattice Antiferromagnet CuFeO2
By means of neutron scattering measurements, we have investigated spin-wave
excitation in a collinear four-sublattice (4SL) magnetic ground state of a
triangular lattice antiferromagnet CuFeO2, which has been of recent interest as
a strongly frustrated magnet, a spin-lattice coupled system and a multiferroic.
To avoid mixing of spin-wave spectrum from magnetic domains having three
different orientations reflecting trigonal symmetry of the crystal structure,
we have applied uniaxial pressure on [1-10] direction of a single crystal
CuFeO2. By elastic neutron scattering measurements, we have found that only 10
MPa of the uniaxial pressure results in almost 'single domain' state in the 4SL
phase. We have thus performed inelastic neutron scattering measurements using
the single domain sample, and have identified two distinct spin- wave branches.
The dispersion relation of the upper spin-wave branch cannot be explained by
the previous theoretical model [R. S. Fishman: J. Appl. Phys. 103 (2008)
07B109]. This implies the importance of the lattice degree of freedom in the
spin-wave excitation in this system, because the previous calculation neglected
the effect of the spin-driven lattice distortion in the 4SL phase. We have also
discussed relationship between the present results and the recently discovered
"electromagnon" excitation.Comment: 5 pages, 3 figures, accepted for publication in J. Phys. Soc. Jp
Discovery of Crystallized Water Ice in a Silhouette Disk in the M43 Region
We present the 1.9--4.2um spectra of the five bright (L<11.2) young stars
associated with silhouette disks with moderate to high inclination angle of
39--80deg in the M42 and M43 regions. The water ice absorption is seen toward
d121-1925 and d216-0939, while the spectra of d182-316, d183-405, and d218-354
show no water ice feature around 3.1um within the detection limits. By
comparing the water ice features toward nearby stars, we find that the water
ice absorption toward d121-1925 and d216-0939 most likely originates from the
foreground material and the surrounding disk, respectively. The angle of the
disk inclination is found to be mainly responsible for the difference of the
optical depth of the water ice among the five young stars. Our results suggest
that there is a critical inclination angle between 65deg and 75deg for the
circumstellar disk where the water ice absorption becomes strong. The average
density at the disk surface of d216-0939 was found to be 6.38x10^(-18) g
cm^(-3). The water ice absorption band in the d216-0939 disk is remarkable in
that the maximum optical depth of the water ice band is at a longer wavelength
than detected before. It indicates that the primary carrier of the feature is
purely crystallized water ice at the surface of the d216-0939 disk with
characteristic size of ~0.8um, which suggests grain growth. This is the first
direct detection of purely crystallized water ice in a silhouette disk.Comment: 28 pages, 8 figures, Accepted by Ap
Malignant melanoma of the nasal cavity: a case report with examination of KIT and platelet derived growth factor receptor-α(PDGFRA)
Although several clinicopathological studies of malignant melanoma of the nasal cavity have been reported, there are no studies of the expression and gene mutation of KIT and platelet derived growth factor receptor-α (PDGFRA) in melanoma of the nasal cavity. A 92-year-old Japanese woman consulted to our hospital because of right nasal obstruction and epistaxis. Physical examination and imaging modalities showed a tumor of the right nasal cavity. A biopsy was taken, and it showed malignant epithelioid cells with melanin deposition. Immunohistochemically, the tumor was positive for S100 protein, HMB45, p53, Ki-67 (labeling=20%), KIT and PDGFRA. The tumor was negative for cytokeratins (AE1/3 and CAM5.2). A genetic analysis using PCR-direct sequencing revealed no mutation of KIT gene (exons 9, 11, 13, and 17) or the PDGFRA gene (exons 12 and 18). The pathological diagnosis was primary malignant melanoma of the nasal cavity. The tumor was reduced in size by local resection and chemotherapy (Darthmose regimen: dacarbazine, carmustine, cisplatine, and tamoxifen), and the patient is now alive and free from metastasis 9 months after the first manifestation. In conclusion, the author reported a case of melanoma of the nasal cavity expressing KIT and PDGFRA without gene mutations of KIT and PDGFRA
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
Cytokeratin-negative small cell lung carcinoma
Cytokeratins (CK) are good markers of epithelial tumors, and most of carcinomas including small cell lung carcinoma (SCLC) expresses CK. Herein reported is a case of SCLC without CK expression
Simulation results of a New type of sandwich calorimeter, Double readout Sandwich Calorimeter (DSC) performance
In this study, we propose a novel fully active total absorption calorimeter
with enhanced read out capabilities through fine splitting. The proposed
calorimeter employs a sandwich structure composed of scintillator glasses and
lead glasses, which are subdivided into small tiles. This configuration enables
the creation of a finely segmented three-dimensional calorimeter that is
compatible with Particle Flow Algorithms (PFA). This article presents a
comprehensive description of the calorimeter design and reports performance
results obtained through simulations. Notable, calorimeter demonstrates
exceptional linearity and energy resolution, closely rivaling that of
homogeneous calorimeters. The simulated calorimeter achieves an impressive
energy resolution of approximately
Myopericytoma of low grade malignancy in the oral cavity
Myopericytoma (MPC) of the oral cavity is extremely rare. Herein reported is a case of MPC of low grade malignancy in the oral cavity. A 61-year-old man noticed a tumor of the cheek mucosa, and admitted to our hospital. Oral examination revealed a reddish elevated tumor of the cheek mucosa. Tumorectomy with wide margins was performed. The clinical diagnosis was pyogenic granuloma. Grossly, the tumor was reddish, and measured 1×1×1 cm. Microscopically, oval to spindle tumor cells with hyperchromatic vesicular nuclei and many vasculatures were seen. The tumor cells were contiguous and mixed with endothelial cells in many blood vessels, thus resembling pericytes. Mitotic figures were scattered. The surgical margins were negative for tumor cells. Immunohistochemically, the tumor cells were positive for vimentin, α-smooth muscle actin and p53. The Ki67 labeling was 40%. The tumor cells were negative for cytokeratins (AE1/3 and CAM5.2), CD31, CD34, S100 protein, HMB45, CD10, vimentin, desmin, and factor VIII-related antigen. The endothelium of the vessels were positive for vimentin, CD31, CD34 and factor VIII-related antigen, but negative for α-smooth muscle actin, p53, cytokeratins (AE1/3 and CAM5.2), S100 protein, HMB45, CD10, vimentin, and desmin. The Ki67 labeling was 5%. Because the pericytoid tumor cells showed α-smooth muscle actin and negative for endothelial markers, MPC was diagnosed. In addition, because there was some atypia and mitotic figures were scatters and also because the tumor cells were positive for p53 and Ki67 labeling was high, a pathological diagnosis of MPC with low grade malignancy was made. No recurrence was observed, and the patient is now free from tumor 6 months after the operation
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