Magnetic cycles at different ages of stars

We study the different patterns of interannual magnetic variability in stars on or near the lower main sequence, approximately solar-type (G-K dwarf) stars in time series of 36 years from the Mount Wilson Observatory Ca\,{\sc ii}\,H\&K survey. Our main aim is to search for correlations between cycles, activity measures and ages. Time-frequency analysis has been used to discern and reveal patterns and morphology of stellar activity cycles, including multiple and changing cycles, in the datasets. Both the results from short-term Fourier transform and its refinement using the Choi-Williams distribution, with better frequency resolution, are presented in this study. Rotational periods of the stars were derived using multi-frequency Fourier analysis.From the studied 29 stars we found at least one activity cycle on 28 of them. Twelve stars, with longer rotational periods ($39.7\pm6.0$ days) have simple, smooth cycles, and the rest of the stars, with on-average much faster rotation ($18.1\pm12.2$ days) show complex and sometimes vigorously changing, multiple cycles. The cycles are longer and quite uniform in the first group ($9.7\pm1.9$ years), while are generally shorter and with greater variety in the second one ($7.6\pm4.9$). There is a clear age division between stars with smooth and complex cycles that follows the known separation between the older and younger stars at around 2 to 3~Gyr of age.Comment: Accepted to Astronomy and Astrophysic

Borders and Blood Pressure: Understanding the Role of Acculturation in a Hypertension Diagnosis Among Hispanic Americans: 2014 California Health Interview Survey

Background: In the U.S. Hispanic population overall, heart disease is the leading cause of death. The prevalence of hypertension among Mexican American immigrants is lower than the general population, yet it is on the rise. Health risks among Hispanics vary depending on their length of stay in the US (as proxy measure of acculturation). The purpose of this study was to examine the association between acculturation and the individual\u27s likelihood of being diagnosed with hypertension among Hispanic Americans. Methods: We used data from the 2014 California Health Interview Survey (CHIS) and performed univariate analysis to examine racial differences in prevalence of hypertension. We also performed a multivariate logistic regression to identify if acculturation was significantly related to hypertension diagnoses, after controlling for sociodemographic characteristics (e.g., age, gender, level of education, marital status), access to care, and health status (e.g., self-reported health status, BMI), among Mexican Americans and all Hispanics, respectively. Results: Of 3,793 Hispanic American participating in the survey, 81.8% were Mexican Americans and 18.2% were other Hispanics. The prevalence of hypertension among Hispanic was 24.0% (95% CI: 21.5%. 26.7%) which was lower than that of African Americans (39.2%, 95% CI 33.7%, 44.9%) and White (30.2%, 95% CI: 28.5%, 31.9%). In multivariate analyses, acculturation was associated with hypertension among Mexican Americans, but not all Hispanics. For both Mexican Americans and Hispanics, age, health status and BMI were associated with having hypertension: Older people, those with poor health status, and overweight and obese people were more likely than their comparison groups to have hypertension. Those without health insurance were less likely to have hypertension. Conclusion: The results show a positive association between length of time in the United States for longer periods of time, and a diagnosis of hypertension. These results, along with others conducted around Hispanic American immigration, acculturation and chronic disease prevalence, help medical providers, to understand the effects of acculturation on specific health care needs among immigrants, and offer suggestions to patients which are culturally sensitive and relevant. Poster presented at AHPA conference in Atlanta Georgia.https://jdc.jefferson.edu/jcphposters/1014/thumbnail.jp

Robust Beamforming for Secrecy Rate in Cooperative Cognitive Radio Multicast Communications

In this paper, we propose a cooperative approach to improve the security of both primary and secondary systems in cognitive radio multicast communications. During their access to the frequency spectrum licensed to the primary users, the secondary unlicensed users assist the primary system in fortifying security by sending a jamming noise to the eavesdroppers, while simultaneously protect themselves from eavesdropping. The main objective of this work is to maximize the secrecy rate of the secondary system, while adhering to all individual primary users' secrecy rate constraints. In the case of passive eavesdroppers and imperfect channel state information knowledge at the transceivers, the utility function of interest is nonconcave and involved constraints are nonconvex, and thus, the optimal solutions are troublesome. To address this problem, we propose an iterative algorithm to arrive at a local optimum of the considered problem. The proposed iterative algorithm is guaranteed to achieve a Karush-Kuhn-Tucker solution.Comment: 6 pages, 4 figures, IEEE ICC 201

BFT Hamiltonian embedding for SU(3) Skyrmion

We newly apply the Batalin, Fradkin and Tyutin (BFT) formalism to the SU(3) flavor Skyrmion model to investigate the Weyl ordering correction to the structure of the hyperfine splittings of strange baryons. On the other hand, the Berry phases and Casimir effects are also discussed.Comment: 14 pages, modified titl

Hyers-Ulam stability of a generalized Hosszu functional equation

In this paper, we investigate the Hyers-Ulam stability of a generalized Hosszu functional equation, namely f(x + y - xy ) + g(xy) = h(x) + k(y), where f, g, h, k are functions of a real variable with values in a Banach space

N,N′-Bis[(E)-4-nitro­benzyl­idene]-4,4′-oxydianiline

The title compound, C26H18N4O5, can be regarded as an extended ether with two terminal nitro groups. The two aryl rings bonded to the central O atom form a dihedral angle of 75.72 (6)°, and the terminal nitro groups are slightly twisted [by 6.4 (2) and 3.3 (3)°] from the benzene rings to which they are attached. The crystal packing exhibits weak inter­molecular C—H⋯O hydrogen bonds and π–π inter­actions [centroid–centroid distances = 3.794 (3) Å]

l2Match: Optimization Techniques on Subgraph Matching Algorithm using Label Pair, Neighboring Label Index, and Jump-Redo method

Graph database is designed to store bidirectional relationships between objects and facilitate the traversal process to extract a subgraph. However, the subgraph matching process is an NP-Complete problem. Existing solutions to this problem usually employ a filter-and-verification framework and a divide-and-conquer method. The filter-and-verification framework minimizes the number of inputs to the verification stage by filtering and pruning invalid candidates as much as possible. Meanwhile, subgraph matching is performed on the substructure decomposed from the larger graph to yield partial embedding. Subsequently, the recursive traversal or set intersection technique combines the partial embedding into a complete subgraph. In this paper, we first present a comprehensive literature review of the state-of-the-art solutions. l2Match, a subgraph isomorphism algorithm for small queries utilizing a Label-Pair Index and filtering method, is then proposed and presented as a proof of concept. Empirical experimentation shows that l2Match outperforms related state-of-the-art solutions, and the proposed methods optimize the existing algorithms.Comment: This short version of this article (6 pages) is accepted by ICEIC 202