Joint Optimization of Power Allocation and Training Duration for Uplink Multiuser MIMO Communications

In this paper, we consider a multiuser multiple-input multiple-output (MU-MIMO) communication system between a base station equipped with multiple antennas and multiple mobile users each equipped with a single antenna. The uplink scenario is considered. The uplink channels are acquired by the base station through a training phase. Two linear processing schemes are considered, namely maximum-ratio combining (MRC) and zero-forcing (ZF). We optimize the training period and optimal training energy under the average and peak power constraint so that an achievable sum rate is maximized.Comment: Submitted to WCN

A Nonconvex Splitting Method for Symmetric Nonnegative Matrix Factorization: Convergence Analysis and Optimality

Symmetric nonnegative matrix factorization (SymNMF) has important applications in data analytics problems such as document clustering, community detection and image segmentation. In this paper, we propose a novel nonconvex variable splitting method for solving SymNMF. The proposed algorithm is guaranteed to converge to the set of Karush-Kuhn-Tucker (KKT) points of the nonconvex SymNMF problem. Furthermore, it achieves a global sublinear convergence rate. We also show that the algorithm can be efficiently implemented in parallel. Further, sufficient conditions are provided which guarantee the global and local optimality of the obtained solutions. Extensive numerical results performed on both synthetic and real data sets suggest that the proposed algorithm converges quickly to a local minimum solution.Comment: IEEE Transactions on Signal Processing (to appear

Liquidity Risk, Return Predictability, and Hedge Funds' Performance: An Empirical Study

This article analyzes the effect of liquidity risk on the performance of equity hedge fund portfolios. Similarly to Avramov, Kosowski, Naik, and Teo (2007), (2011), we observe that, before accounting for the effect of liquidity risk, hedge fund portfolios that incorporate predictability in managerial skills generate superior performance. This outperformance disappears or weakens substantially for most emerging markets, event-driven, and long/short hedge fund portfolios once we account for liquidity risk. Moreover, we show that the equity market-neutral and long/short hedge fund portfolios' "alphas” also entail rents for their service as liquidity providers. These results hold under various robustness test

Effect of Ba-Duan-Jin on Immune Function and Autonomic Nervous Balance in Ageing People

[Objective] Ba-Duan-Jin, formed in the 12th century, is an excellent traditional Chinese health exercises. Ancients likened it to “brocade (Jin)”, meaning its action is as elegant as brocade. The total movements are divided into 8 sections, so it is called “ Ba-Duan-Jin (8-section-action)”. Because of its simple action and significantly healthy effect, Ba-Duan-Jin is widely used to enhance physical fitness and prevent diseases. This study was aimed to evaluate the immunological effect of Ba-Duan-Jin in ageing people and analyze its autonomic nervous mechanism. [Methods] 60 healthy women (64.06±2.53 years old) were divided into exercising group and sedentary group. Exercising group trained Ba-Duan-Jin 12 weeks（5 day/week, 3 repetition/day）. Record electrocardiosignal to analyze heart rate variability (HRV) , and then take blood sample to measure blood routine, immune globulin, complement, sub-T lymphocyte, catecholamines and acetylcholine. These measurements were performed before and after the 8-week’s intervening duration. [Results] The plasma immune globulin, complement, catecholamines and acetylcholine have no significant difference between two groups. But when it came to lymphocyte in peripheral blood, the women in exercising group have less CD8+ T-lymphocyte and higher rate of CD4+/CD8+ than sedentary group. The analysis of HRV showed an increasing total HRV (TF), a enhanced activity of parasympathetic nerve (RRmean, SDNN, RMSSD, HFnorm) and an attenuated activity of sympathetic nerve (LFnorm) in Ba-Duan-Jin exercising group. Correlation analysis confirmed that there is a close relationship between immune function and autonomic nervous activities. [Conclusion] Ba-Duan-Jin can transfer the autonomic nervous balance to parasympathetic dominance, which may partially explain the increasing immunity function (especially in cell immunity) in ageing people. Fig: the 8 sections of Ba-Duan-Jin Note: 1. Holding heaven in the palms2. Posing as an archer shooting3. Holding one arm aloft4. Looking backward5. Swinging the head and lowering the body6. Moving the hands down the back and legs, and touching the Feet7. Thrusting the fists and making the eyes glare8. Raising and Lowering the Heel

Factor Misallocation and Declining Labor Income-Share in China

In China’s present economic development, factor misallocation and labor’s low income-share both are important and interrelated, with factor misallocation being an important reason for the decline in China’s labor income-share. Theoretical modeling demonstrates that if capital-labor is substitutable, the factor misallocation will lead to a decline in labor income-share. Empirical studies, using 2001-2013 provincial panel data show that factor misallocation significantly reduces labor income-share, even after controlling for other factors that affect the labor-share. The conclusion is both significant and robust. Therefore, economic policy which optimizes factor allocation will improve labor’s income-share

The More, The Better? A Case History Of Audit Committee Regulations

An understanding of changing auditing regulatory environment is vital in preparing students for the challenges in the accounting profession. The revised requirements for audit committees are one of the significant changes after the Sarbanes-Oxley Act of 2002. Presenting a case history of regulatory changes for audit committees, this study requires students to critically analyze information and to conduct research on auditing topics. Meanwhile, integrating further discussion on corporate governance into auditing class can enrich students learning experience by stimulating critical thinking

Stability and bifurcation analysis of Westwood+ TCP congestion control model in mobile cloud computing networks

In this paper, we first build up a Westwood+ TCP congestion control model with communication delay in mobile cloud computing networks. We then study the dynamics of this model by analyzing the distribution ranges of eigenvalues of its characteristic equation. Taking communication delay as the bifurcation parameter, we derive the linear stability criteria depending on communication delay. Furthermore, we study the direction of Hopf bifurcation as well as the stability of periodic solution for the Westwood+ TCP congestion control model with communication delay. We find that the Hopf bifurcation occurs when the communication delay passes a sequence of critical values. The stability and direction of the Hopf bifurcation are determined by the normal form theory and the center manifold theorem. Finally, numerical simulation is done to verify the theoretical results