The relationship between radio power at 22 and 43 GHz and black hole properties of AGN in elliptical galaxies

We investigate the relationship between radio power and properties related to active galactic nuclei (AGNs). Radio power at 1.4 or 5 GHz, which has been used in many studies, can be affected by synchrotron self-absorption and free-free absorption in a dense region. On the other hand, these absorption effects get smaller at higher frequencies. Thus, we performed simultaneous observations at 22 and 43 GHz using the Korean VLBI Network (KVN) radio telescope based on a sample of 305 AGN candidates residing in elliptical galaxies from the overlap between the Sloan Digital Sky Survey (SDSS) Data Release 7 and Faint Images of the Radio Sky at Twenty-Centimeters (FIRST). About 37% and 22% of the galaxies are detected at 22 and 43 GHz, respectively. Assuming no flux variability between the FIRST and KVN observation, spectral indices were derived from FIRST and KVN data and we found that over 70% of the detected galaxies have flat or inverted spectra, implying the presence of optically thick compact regions near the centres of the galaxies. Core radio power does not show a clear dependence on black hole mass at either low (1.4 GHz) or high (22 and 43 GHz) frequencies. However, we found that the luminosity of the [OIII] $\lambda$5007 emission line and the Eddington ratio correlate with radio power more closely at high frequencies than at low frequencies. This suggests that radio observation at high frequencies can be an appropriate tool for unveiling the innermost region. In addition, the luminosity of the [OIII] $\lambda$5007 emission line and the Eddington ratio can be used as a tracer of AGN activity. Our study suggests a causal connection between high frequency radio power and optical properties of AGNs.Comment: 14 pages, 13 figures, 5 tables, Accepted for publication in A&

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

A hexagonal array of optically active ZnO nanoparticles was synthesized in situ on the solid substrate by utilizing a single-layered film of diblock copolymer micelles as a nanostructured template.X1135sciescopu

A possible physical connection between helium-rich stellar populations of massive globular clusters and the UV upturn of galactic spheroids

We discuss a possible physical connection between helium-rich (Y > 0.35) stellar populations of massive globular clusters (GCs) and the ultraviolet (UV) upturn of galactic spheroids by using analytical and numerical models. In our model, all stars are initially formed as bound or unbound star clusters (SCs) formed from giant molecular clouds (GMCs) and the SCs can finally become GCs, open clusters, and field stars depending on physical properties of their host GMCs. An essential ingredient of the model is that helium-rich stars are formed almost purely from gas ejected from massive asymptotic giant branch (AGB) stars. The helium-rich star formation is assumed to occur within massive SCs if the masses of the progenitor GMCs are larger than a threshold mass (M_thres). These massive SCs can finally become either massive GCs or helium-rich field stars depending on whether they are disintegrated or not. Using this model, we show that if the initial mass functions (IMFs) in galactic spheroids are mildly top-heavy, then the mass fractions of helium-rich main-sequence stars (F_He) can be as large as ~ 0.1 for M_thres=10^7 M_sun. F_He is found to depend on IMFs and M_thres such that it can be larger for shallower IMFs and smaller M_thres. The inner regions of galactic spheroids show larger F_He in almost all models. Based on these results, we suggest that if the UV upturn of elliptical galaxies is due to the larger fractions of helium-rich stars, then the origin can be closely associated with top-heavy IMFs in the galaxies.Comment: 20 pages, 8 figures, accepted by Ap

The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies

Recent observations and modeling of globular clusters with multiple populations strongly indicate the presence of super helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies. We find that our models with helium- enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old globular clusters in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal- poor and helium-enhanced hot horizontal branch stars and their progeny. The Burstein et al. (1988) relation of the F U V - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in early-type galaxies.Comment: 12 pages, 4 figures, 1 table, Accepted for publication in ApJ

Knowledge of Cardiovascular Medications in a Culturally Diverse Elderly Community: Health Assessment Outcomes by Nursing Students

Lack of knowledge in medication use appears a major hindrance in managing cardiovascular diseases. The cross-sectional study examined the determinants of knowledge of cardiovascular medications in elderly community, using the survey questionnaire and structured interviews to collect data from 99 culturally-diverse elderly people at independent-living facilities in California. Results indicate that the majority of participants was women (82.8%), living alone with an educational level of high-school or higher. Sixty-six participants took at least one cardiovascular medication, and the average number of cardiovascular medications taken was 2.02 (±1.10). The most frequently used cardiovascular medications were lipid-lowering agents and aspirin. Thirtyeight participants demonstrated a lack of knowledge of cardiovascular medication use. After adjusting for age, gender, education, and living status, it was found that having a BMI higher than 25 (OR: 5.46; 95% CI; 1.12, 26.52), drinking alcohol beverages (OR: 0.075; 95% CI: 0.01, 0.83), and having a history of ever-smoking (OR: 54.90; 95% CI: 4.39, 686.29) were statistically significant, independent predictors of a lack of knowledge about cardiovascular medications

Adversarial Learning of Privacy-Preserving and Task-Oriented Representations

Data privacy has emerged as an important issue as data-driven deep learning has been an essential component of modern machine learning systems. For instance, there could be a potential privacy risk of machine learning systems via the model inversion attack, whose goal is to reconstruct the input data from the latent representation of deep networks. Our work aims at learning a privacy-preserving and task-oriented representation to defend against such model inversion attacks. Specifically, we propose an adversarial reconstruction learning framework that prevents the latent representations decoded into original input data. By simulating the expected behavior of adversary, our framework is realized by minimizing the negative pixel reconstruction loss or the negative feature reconstruction (i.e., perceptual distance) loss. We validate the proposed method on face attribute prediction, showing that our method allows protecting visual privacy with a small decrease in utility performance. In addition, we show the utility-privacy trade-off with different choices of hyperparameter for negative perceptual distance loss at training, allowing service providers to determine the right level of privacy-protection with a certain utility performance. Moreover, we provide an extensive study with different selections of features, tasks, and the data to further analyze their influence on privacy protection