200 research outputs found
Effect of dust size and structure on scattered light images of protoplanetary discs
We study scattered light properties of protoplanetary discs at near-infrared
wavelengths for various dust size and structure by performing radiative
transfer simulations. We show that different dust structures might be probed by
measuring disk polarisation fraction as long as the dust radius is larger than
the wavelength. When the radius is larger than the wavelength, disc scattered
light will be highly polarised for highly porous dust aggregates, whereas more
compact dust structure tends to show low polarisation fraction. Next, roles of
monomer radius and fractal dimension for scattered light colours are studied.
We find that, outside the Rayleigh regime, as fractal dimension or monomer
radius increases, colours of the effective albedo at near-infrared wavelengths
vary from blue to red. Our results imply that discs showing grey or slightly
blue colours and high polarisation fraction in near-infrared wavelengths might
be explained by the presence of large porous aggregates containing sub-microns
sized monomers.Comment: Accepted for publication in MNRAS, 18 pages, 19 figure
Utility of a Fluorescence Microscopy Imaging System for Analyzing the DNA Ploidy of Pathological Megakaryocytes Including 5q- Syndrome
To investigate megakaryocyte (MK) DNA ploidy in various hematological diseases, fluorescence microscopy imaging system (FMI) can be used to analyze DNA ploidy with cell morphology at the single-cell level by using specialized image-processing software. Here we compared DNA ploidy obtained by FMI measured with that obtained flow cytometry (FCM). With FMI, we could evaluate the DNA ploidy in long-term preserved bone marrow smear samples after staining. We next analyzed the MK DNA ploidy in 42 bone marrow smear samples including 26 myeloid neoplasm cases, and we compared the DNA ploidy and platelet counts in the patients' peripheral blood; the production of platelets was significantly high compared to DNA ploidy in the myeloproliferative neoplasms group. The FMI method revealed that the patients with 5q- syndrome exhibited relatively low DNA ploidy despite high platelet counts, and this result suggested that increased DNA ploidy is not indispensable to abundant platelet production. The FMI method for DNA ploidy will be a useful tool to clarify the relationship between DNA ploidy and platelet production by MKs
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