Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

Nuclear rings at centers of barred galaxies exhibit strong star formation activities. They are thought to undergo gravitational instability when sufficiently massive. We approximate them as rigidly-rotating isothermal objects and investigate their gravitational instability. Using a self-consistent field method, we first construct their equilibrium sequences specified by two parameters: alpha corresponding to the thermal energy relative to gravitational potential energy, and R_B measuring the ellipticity or ring thickness. Unlike in the incompressible case, not all values of R_B yield an isothermal equilibrium, and the range of R_B for such equilibria shrinks with decreasing alpha. The density distributions in the meridional plane are steeper for smaller alpha, and well approximated by those of infinite cylinders for slender rings. We also calculate the dispersion relations of nonaxisymmetric modes in rigidly-rotating slender rings with angular frequency Omega_0 and central density rho_max. Rings with smaller alpha are found more unstable with a larger unstable range of the azimuthal mode number. The instability is completely suppressed by rotation when Omega_0 exceeds the critical value. The critical angular frequency is found to be almost constant at ~ 0.7 sqrt(G*rho_c) for alpha > 0.01 and increases rapidly for smaller alpha. We apply our results to a sample of observed star-forming rings and confirm that rings without a noticeable azimuthal age gradient of young star clusters are indeed gravitationally unstable.Comment: 17 figures and 2 tables; Accepted for publication in the Ap

A Fast Poisson Solver of Second-Order Accuracy for Isolated Systems in Three-Dimensional Cartesian and Cylindrical Coordinates

We present an accurate and efficient method to calculate the gravitational potential of an isolated system in three-dimensional Cartesian and cylindrical coordinates subject to vacuum (open) boundary conditions. Our method consists of two parts: an interior solver and a boundary solver. The interior solver adopts an eigenfunction expansion method together with a tridiagonal matrix solver to solve the Poisson equation subject to the zero boundary condition. The boundary solver employs James's method to calculate the boundary potential due to the screening charges required to keep the zero boundary condition for the interior solver. A full computation of gravitational potential requires running the interior solver twice and the boundary solver once. We develop a method to compute the discrete Green's function in cylindrical coordinates, which is an integral part of the James algorithm to maintain second-order accuracy. We implement our method in the {\tt Athena++} magnetohydrodynamics code, and perform various tests to check that our solver is second-order accurate and exhibits good parallel performance.Comment: 24 pages, 13 figures; accepted for publication in ApJ

Matching Level And Investors’ Heterogeneous Beliefs

This study investigated the relation between matching level and investors’ heterogeneous beliefs using listed firm (KOSPI) data in Korea. This study is based on prior research that reported that the higher the matching level, the less the noise included in accounting earnings and the higher the earnings quality. Karpoff (1986), Bamber (1987), Ajinkya, Atiase, & Gift (1991) and Dormeier (2011) explain that if there are different interpretations among investors regarding intrinsic value of a company, as a result, the trading volume can represent investors’ heterogeneous beliefs. Whereas the previous studies on matching level analyzed what kind of impact matching level improvement has on earnings quality, accumulated market adjusted return, foreign ownership, future earnings response coefficient (FERC) and bond credit rating. However, these studies have problems in measuring the matching level. So this study suggested additional proxy on matching level in addition to the proxy used in previous studies. Specifically, we analyzed the matching level model of Paek’s (2011b) by using the Prais-Winsten estimation method and then used the calculated explanatory power (Adj.R2) as a proxy for the additional matching level. To empirically analyze hypothesis of this study, we used firm-year observation from 4,094 firms listed on Korean Stock Exchange over the period from 2003 to 2011. We found that matching level regression coefficient consistently showed significantly negative values for each measurement. Moreover, we analyzed additionally by measuring the calculated regression coefficient (?2) of current expenses as matching level response coefficient after analyzing Dichev and Tang’s (2008) matching level measuring model by Prais-Winsten estimation method. It showed that regression coefficient of the current expenses and trading volume have negative correlation. This is consistent with this study, and it can be analyzed that as matching level improves, investors’ heterogeneous beliefs decrease. According to microeconomics theory of Mas-Colell, Whinston, and Green (1995), trading volume is explained to affect price changes. However, accounting and related studies analyze the information effect by using price change only. In this sense, this study is meaningful in that it conducted an analysis on the information effect of matching level through trading volume. In addition, this study contributes to understand the microscopic structure of the capital market

The Effect Of Internal Capital Market Of Korean Large Business Groups On Investment Efficiency

This study examines whether the effect of funding through internal capital markets on investment efficiency is differentiated by the incentives of controlling shareholders as measured by the divergence between cash flow rights and voting rights of controlling shareholders (hereafter, wedge). To empirically analyze hypotheses of this study, 1,189 firm-year observations were collected from Korean firms listed on the Korea Composite Stock Price Index (KOSPI) belonging to a large business group designated by the Korea Fair Trade Commission over the period from 2005 to 2012. The results of the analysis are as follows. First, we find that the magnitude of internal funding, as measured by total payables to the related parties, is positively (+) associated with investment inefficiency. Second, the interaction variables of total payables to the related parties and the wedge have a significant positive (+) effect on investment inefficiency. In other words, the deterioration of investment efficiency due to the increase in total payables to the related parties was mainly caused by firms with a big wedge. This result suggests that the effect of internal capital markets on investment efficiency of large business groups may be differentiated by the wedge that is proxy of the controlling shareholder’s incentive. This study provides additional evidence on previous studies on the investment efficiency of large business groups by considering both the internal capital market and incentives for funding using the internal capital market, which are important factors affecting the investment of large corporate groups. Also, the results of this study are expected to provide implications for the regulatory policy of large business groups which have recently become an issue in Korea

Three Recipes for Better 3D Pseudo-GTs of 3D Human Mesh Estimation in the Wild

Recovering 3D human mesh in the wild is greatly challenging as in-the-wild (ITW) datasets provide only 2D pose ground truths (GTs). Recently, 3D pseudo-GTs have been widely used to train 3D human mesh estimation networks as the 3D pseudo-GTs enable 3D mesh supervision when training the networks on ITW datasets. However, despite the great potential of the 3D pseudo-GTs, there has been no extensive analysis that investigates which factors are important to make more beneficial 3D pseudo-GTs. In this paper, we provide three recipes to obtain highly beneficial 3D pseudo-GTs of ITW datasets. The main challenge is that only 2D-based weak supervision is allowed when obtaining the 3D pseudo-GTs. Each of our three recipes addresses the challenge in each aspect: depth ambiguity, sub-optimality of weak supervision, and implausible articulation. Experimental results show that simply re-training state-of-the-art networks with our new 3D pseudo-GTs elevates their performance to the next level without bells and whistles. The 3D pseudo-GT is publicly available in https://github.com/mks0601/NeuralAnnot_RELEASE.Comment: Published at CVPRW 202

Prediction of Electricity Consumption of a HVAC System in a Multi-Complex Building Using Back Propagation and Radial Basis Function Neural Networks

This study examined approaches to predict electricity consumption of a Heating, Ventilation and Air- Conditioning (HVAC) system in a multi-complex building using two neural network models: Back Propagation (BP) and Radial Basis Function (RBF) with input nodes, e.g., temperature, humidity ratio, and wind speed. Predicting HVAC energy consumption of buildings is a crucial part of energy management systems. We used two main neural network models, BP and RBF, to evaluate the prediction performance of electricity consumption of HVAC systems. The BP neural network method exhibited good performance, but it exhibited relatively large fluctuations and slow convergence in the training process. In contrast, RBF exhibited relatively fast learning and reduced computing costs. The HVAC energy consumption rate of working days was higher than that of non-working days. The results indicate that the prediction of HVAC energy consumption using neural networks can effectively control the relationship between the HVAC system and environment conditions.publishedVersio

Optimal Message Bundling with Delay and Synchronization Constraints in Wireless Sensor Networks

Energy efficiency and end-to-end delay are two of the major requirements for the monitoring and detection applications based on resource-constrained wireless sensor networks (WSNs). As new advanced technologies for accurate monitoring and detection—such as device-free wireless sensing schemes for human activity and gesture recognition—have been developed, time synchronization accuracy becomes an important requirement for those WSN applications too. Message bundling is considered one of the effective methods to reduce the energy consumption for message transmissions in WSNs, but bundling more messages increases the transmission interval of bundled messages and thereby their end-to-end delays; the end-to-end delays need to be maintained within a certain value for time-sensitive applications like factory monitoring and disaster prevention, while the message transmission interval affects time synchronization accuracy when the bundling includes synchronization messages as well. Taking as an example a novel WSN time synchronization scheme recently proposed for energy efficiency, we investigate an optimal approach for message bundling to reduce the number of message transmissions while maintaining the user-defined requirements on end-to-end delay and time synchronization accuracy. Formulating the optimal message bundling problem as integer linear programming, we compute a set of optimal bundling numbers for the sensor nodes to constrain their link-level delays, thereby achieving and maintaining the required end-to-end delay and synchronization accuracy. Extensive experimental results based on a real WSN testbed using TelosB sensor nodes demonstrate that the proposed optimal bundling could reduce the number of message transmissions about 70% while simultaneously maintaining the required end-to-end delay and time synchronization accuracy

WISDOM Project - XXI. Giant molecular clouds in the central region of the barred spiral galaxy NGC 613: a steep size - linewidth relation

NGC 613 is a nearby barred spiral galaxy with a nuclear ring. Exploiting high spatial resolution (≈20 pc) Atacama Large Millimetre/submillimetre Array 12CO(1–0) observations, we study the giant molecular clouds (GMCs) in the nuclear ring and its vicinity, identifying 158 spatially and spectrally resolved GMCs. The GMC sizes (Rc) are comparable to those of the clouds in the Milky Way (MW) disc, but their gas masses, observed linewidths (σobs,los), and gas mass surface densities are larger. The GMC size–linewidth relation (⁠ ⁠) is steeper than that of the clouds of the MW disc and centre, and the GMCs are on average only marginally gravitationally bound (with a mean virial parameter 〈αobs,vir〉 ≈ 1.7). We discuss the possible origins of the steep size–linewidth relation and enhanced observed linewidths of the clouds and suggest that a combination of mechanisms such as stellar feedback, gas accretion, and cloud–cloud collisions, as well as the gas inflows driven by the large-scale bar, may play a role

Relation Between Real Earnings Management And Audit Quality

Net income is composed of CFO and accruals. Auditors generally detect discretionary accruals to raise reliability of financial reporting and call upon managers to correct their financial reports according to the materiality. From these viewpoints, prior researches use the size of discretionary accruals as proxies for the audit quality. However, manager can also use CFO factors as means of earnings management. We confirm whether abnormal CFO factors, that is, real activity earnings management (hereafter RAM) by Roychordhury model(2006), can be as a proxy for the audit quality with comparing the size of RAM with existing proxies of audit quality such as auditors’ size (e.g. big4), audit time and audit fee. Our results show that the size of RAM is positively correlated with some existing proxies of audit quality. Also, we find discretionary accruals positively correlated with RAM in Korea. The result implies managers in Korea simultaneously use RAM as well as discretionary accruals as a means of earnings management