Derivation of classical capacity of quantum channel for discrete information source

In this letter, we prove that the classical capacity of quantum channel for $M$ symmetric states is achieved by an uniform distribution on a priori probabilities. We also investigate non-symmetric cases such as a ternary amplitude shift keyed signal set and a 16-ary quadrature amplitude modulated signal set in coherent states.Comment: 9 pages, RevTeX, 3 figures(EPSF

Realization of a collective decoding of codeword states

This was also extended from the previous article quant-ph/9705043, especially in a realization of the decoding process.Comment: 6 pages, RevTeX, 4 figures(EPS

Accessible information and optimal strategies for real symmetrical quantum sources

We study the problem of optimizing the Shannon mutual information for sources of real quantum states i.e. sources for which there is a basis in which all the states have only real components. We consider in detail the sources ${\cal E}_M$ of $M$ equiprobable qubit states lying symmetrically around the great circle of real states on the Bloch sphere and give a variety of explicit optimal strategies. We also consider general real group-covariant sources for which the group acts irreducibly on the subset of all real states and prove the existence of a real group-covariant optimal strategy, extending a theorem of Davies (E. B. Davies, IEEE. Inf. Theory {\bf IT-24}, 596 (1978)). Finally we propose an optical scheme to implement our optimal strategies, enough simple to be realized with present technology.Comment: RevTeX, 16 pages, 4 eps figures with psfig, submitted to Phys. Rev. A, corrected output error of Fig. 1 in the previous versio

Physical Meaning of the Optimum Measurement Process in Quantum Detection Theory

The optimum measurement processes are represented as the optimum detection operators in the quantum detection theory. The error probability by the optimum detection operators goes beyond the standard quantum limit automatically. However the optimum detection operators are given by pure mathematical descriptions. In order to realize a communication system overcoming the standard quantum limit, we try to give the physical meaning of the optimum detection operators

Gender differences in dietary behaviors among Japanese adolescents

Unhealthy dietary behaviors in adolescence are an important public health problem. Gender differences in dietary behaviors have already appeared during adolescence. However, few studies have assessed a variety of adolescent dietary behaviors in Japan. We aimed to clarify gender differences in unhealthy dietary behaviors among Japanese adolescents. The participants consisted of 84,988 participants from seventh to 12th grades. Unhealthy dietary behaviors were defined according to the National Health and Nutrition Survey. Multivariable logistic regression was used to analyze a nationally representative sample of Japanese adolescents from the 2014 to 2015 Lifestyle Survey. The effective response rate was 51.4%. The prevalence of unhealthy dietary behaviors (skipping breakfast, snacking, eating out, skipping meals, eating alone at dinner, and subjectively poor diet quality) among boys and girls was 14.2% versus 12.4%, 19.6% versus 14.1%, 10.6% versus 7.0%, 7.9% versus 5.6%, 13.3% versus 12.1%, and 12.3% versus 15.8%, respectively. Compared with boys, girls were more negatively associated with skipping breakfast [OR = 0.76 (95% CI 0.73–0.79)], snacking [OR = 0.67 (95% CI 0.65–0.70)], eating out [OR = 0.62 (95% CI 0.59–0.66)], skipping meals [OR = 0.61 (95% CI 0.58–0.65)], and eating alone at dinner [OR = 0.79 (95% CI 0.76–0.83)]. However, girls were more positively associated with subjectively poor diet quality [OR = 1.19 (95% CI 1.14.1.24)]. The findings suggest that gender differences existed in dietary behaviors. Gender differences in dietary behaviors suggest opportunities for tailoring interventions related to dietary education in schools

Design and Performance of Superconducting Magnets for Hybrid Magnets(Part I. Establishment and Tests of Hybrid Magnet System at HFLSM)

Design, construction and performance of three superconducting magnets for the hybrid magnets installed in the High Field Laboratory for Superconducting Materials are described in detail. The compact solenoid, SM-3, without fully cryostable design forms the outer part of the most compact hybrid magnet in the world, HM-3 (32 mm bore, 20 T). Fully cryostable superconducting magnet designed under the Steckly criterion, SM-2, is the outer part of HM-2 (52 mm bore, 23 T), which has been most attractive to many experimentalists. SM-1, the outer part of HM-1 (32/52 mm bore, 31/28 T), with the Williams cryostability criterion is the world largest one of the superconducting magnets which employ Ti-doped Nb_3Sn multifilamentary conductors and can generate more than 12 T

Trends in sleep problems and patterns among Japanese adolescents: 2004 to 2017

Background Sleep problems in adolescence, such as insomnia and short sleep duration, are associated with physical and mental health problems. However, little is known about the recent trends in sleep problems among adolescents. Therefore, this study examined trends in sleep problems among Japanese adolescents. Methods Using data from the Lifestyle Survey of Adolescents collected in 2004 (n = 102,451), 2008 (n = 95,680), 2010 (n = 98,867), 2012 (n = 101,134), 2014 (n = 85,931), and 2017 (n = 64,417), we calculated the trends of insomnia, shorter sleep duration, late bedtimes, and poor sleep quality. Multivariable logistic regression analysis models were used to examine the association of each sleep problem and survey years. Findings We analyzed data from 545,285 Japanese adolescents. Results indicated that, since 2004, the odds ratio for insomnia have decreased (Adjusted odds ratio [AOR] 0•85, 95% CI 0•82–0•87), as have the odds ratio for poor sleep quality (AOR 0•92, 95% CI 0•88–0•95). However, the odds ratio for shorter sleep duration (AOR 1•13, 95% CI 1•10–1•17) and late bedtimes tended to increase (AOR 1•06, 95% CI 1•03–1•08) during this period. Interpretation The prevalence of insomnia symptoms and poor sleep quality among adolescents decreased from 2004 to 2017. However, there were increasing trends toward shorter sleep duration and late bedtimes. These changes are both relieving and concerning. Teachers, parents, and health professionals should consider educating adolescents regarding sleep hygiene, adjusting schedules of extracurricular activities, and enhancing time management to improve their sleep quantity

General Survey of Tohoku Hybrid Magnet System(Part I. Establishment and Tests of Hybrid Magnet System at HFLSM)

Outline of Tohoku Hybrid Magnet system is briefly described. High Field Laboratory was established in the Research Institute for Iron, Steel and Other Metals, Tohoku University, in 1981, for accelerating research and development of high field superconducting materials. Three hybrid magnets generating magnetic fields more than 20 T have been constructed as its main apparatuses. The strongest hybrid magnet, HM-1, could produce 31.1 T in November, 1986, which was the world record as this kind of hybrid magnet. Several important features of the hybrid magnet system are introduced which will be also useful to understand the following papers