1,583 research outputs found
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 -shift cross-orthogonal sequence families
(-CO-SFs). We show theoretical bounds on the size of -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
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