A Systematic Framework for the Construction of Optimal Complete Complementary Codes

The complete complementary code (CCC) is a sequence family with ideal correlation sums which was proposed by Suehiro and Hatori. Numerous literatures show its applications to direct-spread code-division multiple access (DS-CDMA) systems for inter-channel interference (ICI)-free communication with improved spectral efficiency. In this paper, we propose a systematic framework for the construction of CCCs based on $N$-shift cross-orthogonal sequence families ($N$-CO-SFs). We show theoretical bounds on the size of $N$-CO-SFs and CCCs, and give a set of four algorithms for their generation and extension. The algorithms are optimal in the sense that the size of resulted sequence families achieves theoretical bounds and, with the algorithms, we can construct an optimal CCC consisting of sequences whose lengths are not only almost arbitrary but even variable between sequence families. We also discuss the family size, alphabet size, and lengths of constructible CCCs based on the proposed algorithms

Nucleus from String Theory

In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass number (A) dependence r A^{1/3} for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multi-baryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1) x A^{1/3} [fm], which is consistent with experiments.Comment: 4 pages; Ver.2: terminology on nuclear density saturation modified, a reference adde

The meaning of kindness and gratitude in Japan: A mixed-methods study

Kindness and gratitude expression have significant wellbeing enhancing effects. However, the effect of engaging in these activities may be influenced by cultural factors. The purpose of this research was to explore how Japanese young adults construe kindness and gratitude, as well as to investigate the effect of kindness and gratitude expression on their wellbeing. Fifty-eight Japanese students were randomly allocated to three groups: acts of kindness, gratitude expression, and memorable events (as control), and engaged in the activities for three weeks. Exploratory content analysis revealed that participants in the kindness and gratitude groups referred to similar types of social support when describing the activities they had engaged in, including instrumental support (offering objects), emotional support (encouragement), and informational support (teaching). As for the effect of kindness and gratitude on wellbeing, analyses revealed a significant decrease in depression and negative affect from pretest to posttest in all groups. Future research should clarify whether practicing the character strengths of kindness and gratitude is effective for participants with an Asian-cultural background