Error Performance of Amplitude Shift Keying-Type Asymmetric Quantum Communication Systems.

We propose an amplitude shift keying-type asymmetric quantum communication (AQC) system that uses an entangled state. As a first step toward development of this system, we evaluated and considered the communication performance of the proposed receiver when applied to the AQC system using a two-mode squeezed vacuum state (TSVS), the maximum quasi-Bell state, and the non-maximum quasi-Bell state, along with an asymmetric classical communication (ACC) system using the coherent state. Specifically, we derived an analytical expression for the error probability of the AQC system using the quasi-Bell state. Comparison of the error probabilities of the ACC system and the AQC systems when using the TSVS and the quasi-Bell state shows that the AQC system using the quasi-Bell state offers a clear performance advantage under specific conditions. Additionally, it was clarified that there are cases where the universal lower bound on the error probability for the AQC system was almost achieved when using the quasi-Bell state, unlike the case in which the TSVS was used.

Simplification of the Gram Matrix Eigenvalue Problem for Quadrature Amplitude Modulation Signals.

In quantum information science, it is very important to solve the eigenvalue problem of the Gram matrix for quantum signals. This allows various quantities to be calculated, such as the error probability, mutual information, channel capacity, and the upper and lower bounds of the reliability function. Solving the eigenvalue problem also provides a matrix representation of quantum signals, which is useful for simulating quantum systems. In the case of symmetric signals, analytic solutions to the eigenvalue problem of the Gram matrix have been obtained, and efficient computations are possible. However, for asymmetric signals, there is no analytic solution and universal numerical algorithms that must be used, rendering the computations inefficient. Recently, we have shown that, for asymmetric signals such as amplitude-shift keying coherent-state signals, the Gram matrix eigenvalue problem can be simplified by exploiting its partial symmetry. In this paper, we clarify a method for simplifying the eigenvalue problem of the Gram matrix for quadrature amplitude modulation (QAM) signals, which are extremely important for applications in quantum communication and quantum ciphers. The results presented in this paper are applicable to ordinary QAM signals as well as modified QAM signals, which enhance the security of quantum cryptography.

Perception of and anxiety about COVID-19 infection and risk behaviors for spreading infection: An international comparison

To control the spread of the newly developed corona viral infection diseases (COVID-19), peoples appropriate precautionary behaviors should be promoted. We conducted a series of online questionnaire survey, to gather a total of 8,000 citizens responses on March 27-28, 2020 in Japan and April 17-21 in the UK and Spain. Compared to Japan, the knowledge and anxiety level and the frequency of precautionary behaviors were higher in the UK and Spain. Participants with infected acquaintances were more concerned about COVID-19. However, participants in the UK rarely wore a medical mask. Participants in the UK and Spain were eager to get information about COVID-19 compared to those in Japan. The participants in Spain tended not to trust official information and to believe specialists' comments instead. The urgency of the spread of COVID-19, cultural backgrounds, and recent political situations appear to contribute to the differences among countries revealed herein.

Prevalence of Chronic Nonspecific Low Back Pain and Its Associated Factors among Middle-Aged and Elderly People: An Analysis Based on Data from a Musculoskeletal Examination in Japan

STUDY DESIGN: A cross-sectional study. PURPOSE: To clarify the prevalence of chronic nonspecific low back pain (CNSLBP) and its associated factors among middle-aged and elderly Japanese individuals using data from a musculoskeletal examination conducted in general Japanese populations. OVERVIEW OF LITERATURE: Most studies evaluating low back pain-associated factors have been conducted in Western countries, but they have not always evaluated CNSLBP. METHODS: We obtained data on 213 subjects aged >50 years who responded to a survey regarding age, gender, body mass index, lifestyle-related diseases (diabetes mellitus, hypertension, and hyperlipidemia), glucocorticoid use, smoking and alcohol-drinking habits, labor intensity, and chronic low back pain (CLBP) and underwent screening for lumbar spinal stenosis, evaluation for quality of life (QOL), and evaluation for specific spinal pathology via thoracolumbar spine X-rays. We investigated the prevalence of CNSLBP and association between CNSLBP and measured variables. RESULTS: The prevalence of CNSLBP and chronic specific low back pain (CSLBP) was 15.4% and 9.3%, respectively. Among the subjects with CLBP, 62.2% had CNSLBP. In age-adjusted logistic models, smoking habits (p=0.049, odds ratio [OR]=2.594), low back pain (p < 0.001, OR=0.974), lumbar function (p=0.001, OR=0.967), and social function (p=0.023, OR=0.976) in the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were significantly associated with CNSLBP, whereas EQ-5D utility score (p=0.024, OR=0.068), low back pain (p=0.007, OR=0.981), lumbar function (p=0.001, OR=0.963), walking ability (p=0.001, OR=0.968), and social function (p=0.002, OR=0.966) in JOABPEQ were significantly associated with CSLBP. CONCLUSIONS: CNSLBP among middle-aged and elderly individuals was associated with smoking habits and decreased QOL; however, CSLBP was considered to be more multilaterally associated decreased QOL.

An Open Study of Sulforaphane-rich Broccoli Sprout Extract in Patients with Schizophrenia

OBJECTIVE: Schizophrenia is a mental disorder characterized by severe cognitive impairment. Accumulating evidence suggests a role for oxidative stress in the pathophysiology of schizophrenia. Sulforaphane (SFN) extracted from broccoli sprout is an agent with potent anti-oxidant and anti-inflammatory activity. In this study, we attempted to evaluate the effect of SFN on cognitive impairment in medicated patients with schizophrenia. METHODS: We recruited a total of 10 outpatients with schizophrenia, all of whom gave informed consent. Participants took 3 tablets of SFN, consisting of 30 mg of SFN-glucosinolate per day, for 8 weeks. Clinical symptoms using the Positive and Negative Syndrome Scale (PANSS) and cognitive function using the Japanese version of CogState battery were evaluated at the beginning of the study and at week 8. RESULTS: A total of 7 patients completed the trial. The mean score in the Accuracy component of the One Card Learning Task increased significantly after the trial. However, we detected no other significant changes in participants. CONCLUSION: This result suggests that SFN has the potential to improve cognitive function in patients with schizophrenia.