Kazuyuki Tamura

Mapping the spatial distribution of dust extinction in NGC 959 using broadband visible and mid-infrared filters

We present a method to estimate and map the two-dimensional distribution of dust extinction in the late-type spiral galaxy NGC 959 from the theoretical and observed flux ratio of optical V and mid-IR (MIR) 3.6 μm images. Our method is applicable to both young and old stellar populations for a range of metallicities, and is not restricted to lines of sight toward star-formation (SF) regions. We explore this method using a pixel-based analysis on images of NGC 959 obtained in the V band at the Vatican Advanced Technology Telescope and at 3.6 μm (L band) with Spitzer/Infrared Array Camera. We present the original and extinction corrected Galaxy Evolution Explorer (GALEX) far-UV (FUV) and near-UV (NUV) images, as well as optical UBVR images of NGC 959. While the dust lanes are not clearly evident at GALEX resolution, our dust map clearly traces the dust that can be seen silhouetted against the galaxys disk in the high-resolution Hubble Space Telescope (HST) images of NGC 959. The advantages of our method are (1) it only depends on two relatively common broadband images in the optical V band and in the MIR at 3.6 μm (but adding a near-UV band improves its fidelity); and (2) it is able to map the two-dimensional spatial distribution of dust within a galaxy. This powerful tool could be used to measure the detailed distribution of dust extinction within higher redshift galaxies to be observed with, e.g., the Hubble Space Telescope (HST)/WFC3 (optical near-IR) and James Webb Space Telescope (mid-IR), and to distinguish properties of dust within galaxy bulges, spiral arms, and inter-arm regions.

LIFTING THE VEIL OF DUST FROM NGC 0959: THE IMPORTANCE OF A PIXEL-BASED TWO-DIMENSIONAL EXTINCTION CORRECTION

ABSTRACTWe present the results of a study of the late-type spiral galaxy NGC 0959, before and after application of thepixel-based dust extinction correction described in Tamura et al. (Paper I). Galaxy Evolution Explorer far-UV,and near-UV, ground-based Vatican Advanced Technology Telescope, UBVR , and Spitzer/ Infrared Array Camera3.6, 4.5, 5.8, and 8.0 μ m images are studied through pixel color–magnitude diagrams and pixel color–colordiagrams (pCCDs). We define groups of pixels based on their distribution in a pCCD of ( B − 3.6 μ m)versus (FUV − U ) colors after extinction correction. In the same pCCD, we trace their locations beforethe extinction correction was applied. This shows that selecting pixel groups is not meaningful when usingcolors uncorrected for dust. We also trace the distribution of the pixel groups on a pixel coordinate map ofthe galaxy. We find that the pixel-based (two-dimensional) extinction correction is crucial for revealing thespatial variations in the dominant stellar population, averaged over each resolution element. Different types andmixtures of stellar populations, and galaxy structures such as a previously unrecognized bar, become readilydiscernible in the extinction-corrected pCCD and as coherent spatial structures in the pixel coordinate map.

A semi-automated analysis method of small sensory nerve fibers in human skin-biopsies

Computerized detection method (CDM) software programs have been extensively developed in the field of astronomy to process and analyze images from nearby bright stars to tiny galaxies at the edge of the Universe. These object-recognition algorithms have potentially broader applications, including the detection and quantification of cutaneous small sensory nerve fibers (SSNFs) found in the dermal and epidermal layers, and in the intervening basement membrane of a skin punch biopsy. Here, we report the use of astronomical software adapted as a semi-automated method to perform density measurements of SSNFs in skin-biopsies imaged by Laser Scanning Confocal Microscopy (LSCM). In the first half of the paper, we present a detailed description of how the CDM is applied to analyze the images of skin punch biopsies. We compare the CDM results to the visual classification results in the second half of the paper. Abbreviations used in the paper, description of each astronomical tools, and their basic settings and how-tos are described in the appendices. Comparison between the normalized CDM and the visual classification results on identical images demonstrates that the two density measurements are comparable. The CDM therefore can be used - at a relatively low cost - as a quick (a few hours for entire processing of a single biopsy with 8-10 scans) and reliable (high-repeatability with minimum user-dependence) method to determine the densities of SSNFs.

Laminated Specimens of Polystyrene Foams for Microscopic Observation of Two-Dimensional Structure

We developed a teaching material for a microscopic observation of two-dimensional structure of polystyrene foams. The specimen is made with a thin slice of polystyrene foam laminated in between polyethylene terephthalate films. Using this teaching material, we practiced a series of learning activities for high school students to study structure and physical properties of polystyrene foams. Based on their learning, we conclude this teaching material is useful for understanding physical properties of foams in relation to everyday life and products at high school science classes.