Subspace subcodes of Reed-Solomon codes

We introduce a class of nonlinear cyclic error-correcting codes, which we call subspace subcodes of Reed-Solomon (SSRS) codes. An SSRS code is a subset of a parent Reed-Solomon (RS) code consisting of the RS codewords whose components all lie in a fixed ν-dimensional vector subspace S of GF (2m). SSRS codes are constructed using properties of the Galois field GF(2m). They are not linear over the field GF(2ν), which does not come into play, but rather are Abelian group codes over S. However, they are linear over GF(2), and the symbol-wise cyclic shift of any codeword is also a codeword. Our main result is an explicit but complicated formula for the dimension of an SSRS code. It implies a simple lower bound, which gives the true value of the dimension for most, though not all, subspaces. We also prove several important duality properties. We present some numerical examples, which show, among other things, that (1) SSRS codes can have a higher dimension than comparable subfield subcodes of RS codes, so that even if GF(2ν) is a subfield of GF(2m), it may not be the best ν-dimensional subspace for constructing SSRS codes; and (2) many high-rate SSRS codes have a larger dimension than any previously known code with the same values of n, d, and q, including algebraic-geometry codes. These examples suggest that high-rate SSRS codes are promising candidates to replace Reed-Solomon codes in high-performance transmission and storage systems

X-ray dose reduction using additional copper filtration for abdominal digital radiography: Evaluation using signal difference-to-noise ratio

Purpose: X-ray dose reduction using additional copper filters (Cu-filters) for abdominal general radiography was indicated in a report using a simulation study. We validated the dose reduction effects using a clinical digital radiography system equipped with an indirect-type CsI detector and an automatic Cu-filter insertion function. Methods: The image qualities were evaluated using signal difference-to-noise ratio (SDNR) for different radiation qualities with and without Cu-filters for a 20-cm acrylic phantom. Acrylic and bone equivalent material plates were used for contrast measurements. The dose reduction using Cu-filters was estimated from the ratios of the SDNR2 values. Results: For the same entrance surface dose (ESD), Cu-filters with 0.1- and 0.2-mm thicknesses increased the image quality as evaluated by SDNR2 and the estimated dose reduction without degrading the image quality. For the acrylic contrast, the dose reductions with the 0.1- and 0.2-mm-thick Cu-filters were approximately 30% and 44% at 70kV and 29% and 35% at 80kV, respectively. For the bone contrast, the reduction rates were slightly reduced. Conclusions: We validated the dose reduction capability of additional Cu-filters without degrading the image quality for abdominal radiography. The estimated entrance surface dose reductions of the Cu-filters were approximately 30-40% and 20-30% for the acrylic and bone contrasts, respectively, and effective dose reductions for acrylic were nearly half of those for ESD. At these reduced dose conditions, the current time product values needed to be increased by factors of 1.4 and 1.8 for the 0.1- and 0.2-mm-thick Cu-filters, respectively. © 2017 Associazione Italiana di Fisica Medica.Embargo Period 12 month

Statistical Properties of the Nebular Spectra of 103 Stripped-envelope Core-collapse Supernovae

We present an analysis of the nebular spectra of 103 stripped-envelope (SE) supernovae (SNe) collected from the literature and observed with the Subaru Telescope from 2002 to 2012, focusing on [O i] λλ6300, 6363. The line profile and width of [O i] are employed to infer the ejecta geometry and the expansion velocity of the inner core; these two measurements are then compared with the SN subtypes, and further with the [O i]/[Ca ii] ratio, which is used as an indicator of the progenitor CO core mass. Based on the best-fit results of the [O i] profile, the objects are classified into different morphological groups, and we conclude that the deviation from spherical symmetry is a common feature for all types of SESNe. There is a hint (at the ∼1σ level) that the distributions of the line profile fractions are different between canonical SESNe and broad-line SNe Ic. A correlation between [O i] width and [O i]/[Ca ii] is discerned, indicating that the oxygen-rich material tends to expand faster for objects with a more massive CO core. Such a correlation can be utilized to constrain the relation between the progenitor mass and the kinetic energy of the explosion. Further, when [O i]/[Ca ii] increases, the fraction of objects with Gaussian [O i] profile increases, while those with double-peaked profile decreases. This phenomenon connects ejecta geometry and the progenitor CO core mass

Phylogenetic examination of crude drugs derived from Yunnanese Swertia plants

Aiming to examine whether the genetic background of the crude drugs derived from four Yunnanese Swertia plants and their chemical constituent profiles correlate, we analyzed the nucleotide sequences of their nuclear ribosomal DNA regions including ITS1, 5.8S ribosomal RNA gene, and ITS2, together with those of Japanese S. japonica and S. pseudochinensis from Hebei Province. The result that two of the Yunnanese Swertia plants, S. binchuanensis and S. punicea, were genetically similar may explain their similarity in chemical constituent profiles. On the other hand, in spite of differences in chemical profile, S. decora and S. pseudochinensis were genetically close. The other Yunnanese Swertia plants, S. delavayi, and S. japonica, stood at intermediate positions between these two genetically similar pairs. The result suggests that although genetic background would have an influence, environmental factors, e.g., soil and weather conditions, might be critical for their production of secondary metabolites. © The Japanese Society of Pharmacognosy and Springer Japan 2013

High Contrast and High Angular Imaging at Subaru Telescope

Adaptive Optics projects at Subaru Telescope span a wide field of capabilities ranging from ground-layer adaptive optics (GLAO) providing partial correction over a 20 arcmin FOV to extreme adaptive optics (ExAO) for exoplanet imaging. We describe in this paper current and upcoming narrow field-of-view capabilities provided by the Subaru Extreme Adaptive Optics Adaptive Optics (SCExAO) system and its instrument modules, as well as the upcoming 3000-actuator upgrade of the Nasmyth AO system.Comment: 11 pages, to appear in SPIE Proceedings of Astronomical Telescopes + Instrumentation, 202