Efficiency of Stock Exchange Markets in G7 Countries： Bootstrap Causality Approach

Market efficiency is based on efficient market hypothesis （EMH）. EMH claims that market totally contains the available information. In case of EMH, valid investors who take position will not gain abnormal profits. If the efficiency can not be established, that is, if markets are not efficient, investors will have the opportunity of abnormal profits. This paper investigates the causality relations to determine validity of EMH among G7 （Canada, France, Germany, Italy, Japan, United Kingdom, and United States） countries＇ stock exchange markets for the period from July 2003 to October 2014. To find out whether the variables cause each other or not provides knowledge about the market efficiency. The implication of this analysis is twofold. One implication is that if the markets are informationally efficient, the possibility of abnormal returns through arbitrage is ruled out and investors can reduce the risk of their investment for the same expected returns, if they establish portfolios that consist of both markets rather than consisting of only one market. Based on this, Hacker-Hatemi-J. bootstrap causality test that is newer and has many advantages contrary to other tests was used. Results showed that EMH is valid among each G7 countries＇ stock exchange markets. Also portfolio diversification benefits exist among these markets.

The Information Efficiency and Functionality Efficiency of Stock Markets

The efficiency of a stock market is principally measured by its information efficiency and functionality efficiency. Both metrics are closdy related to the information of stock markets. However, there is no uniform definition of information in the economy field since researchers may have various opinions on the information of stock markets. In this research, a comparatively strict definition of information in sense of economy is presented. Based on this definition, the optimal conditions to reach the maximum information efficiency and functionality efficiency of stock markets are derived. The conclusion is, only when the market＇s operation and information transmission mechanisms are fully effective, its information completeness degree is optimal, all investors take optimal equilibrium actions, and the information efficiency and functionality efficiency of stock markets will be optimal. Based on the conclusions, the information efficiency and functionality efficiency of reality stock markets in China are studied and the corresponding supervision countermeasures are suggested.

Temperature Effects on Information Capacity and Energy Efficiency of Hodgkin-Huxley Neuron

Recent experimental and theoretical studies show that energy efficiency, which measures the amount of infor- mation processed by a neuron with per unit of energy consumption, plays an important role in the evolution of neural systems. Here we calculate the information rates and energy efficieneies of the Hodgkin-Huxley （HH） neuron model at different temperatures in a noisy environment. It is found that both the information rate and energy efficiency are maximized by certain temperatures. Though the information rate and energy efficiency cannot be maximized simultaneously, the neuron holds a high information processing capacity at the tempera- ture corresponding to the maximal energy efficiency. Our results support the idea that the energy efficiency is a selective pressure that influences the evolution of nervous systems.

Optimal Size for Maximal Energy Efficiency in Information Processing of Biological Systems Due to Bistability

Energy efficiency is closely related to the evolution of biological systems and is important to their information processing. In this work, we calculate the excitation probability of a simple model of a bistable biological unit in response to pulsatile inputs, and its spontaneous excitation rate due to noise perturbation. Then we analytically calculate the mutual information, energy cost, and energy efficiency of an array of these bistable units. We find that the optimal number of units could maximize this array＇s energy efficiency in encoding pulse inputs, which depends on the fixed energy cost. We conclude that demand for energy efficiency in biological systems may strongly influence the size of these systems under the pressure of natural selection.

The Information Efficiency of QFII's Investment in China's Capital Market

This paper takes stock price synchronization and price delay as indicators of information efficiency, and uses mixed cross-sectional data of listed companies into which Qualified Foreign Institutional Investors(QFII) have made investments, to study the impact of QFII's investment behaviors on the information efficiency of China's stock market. The results show that QFII's investments can improve the information efficiency of China's stock market, but its impact is varied. The impact of QFII's investments on market information efficiency is more significant in bear markets than in bull markets, the impact on private enterprises is more significant than on state-owned enterprises, and the impact on Small and Medium Enterprises(SME) market is more significant than in main board market. Further research also finds that QFII has a certain threshold effect on the information efficiency of China's stock market. This research paper provides a problem-solving perspective for China's capital markets to achieve information efficiency through opening up, and at the same time warns against financial risks.

Does Margin Trading Enhance Information Efficiency of the Capital Market?——Evidence from China

On March 31,2010,China formally introduced a margin trading system,which announced that China's capital market has completed the transformation from a unilateral transaction model to a bilateral transaction model with a short-selling mechanism.However,the current development of China's margin trading and securities lending businesses is seriously unbalanced,and the scale of financing far exceeds the scale of securities lending.The short selling effect of securities lending exchanges is extremely limited,which to some extent violates the original intention of introducing the system.In order to help margin trading and securities lending to correct a healthy and sustainable development path,this article uses stock price synchronicity as a proxy indicator to measure the information efficiency of the capital market,explores the impact of the margin trading system on the information efficiency of the capital market,and study the detailed characteristics and economic consequences of the margin trading system.Aiming at this topic,this article analyzes the relationship between margin financing and securities lending and stock price synchronicity.Finally,it analyzes the influence of margin financing and securities lending system on stock price synchronicity from three dimensions of corporate governance,external supervision,and institutional environment mechanism.In terms of empirical research,this article takes advantage of the“quasi-natural experiment”provided by the gradual opening of margin trading and securities lending in China’s securities market,and selects listed companies on the Shanghai and Shenzhen stock exchanges from 2007 to 2019 as the research objects,starting from the perspective of stock price synchronicity,and passing The DID-FE model studies the impact of the margin trading and securities lending system on the information efficiency of the capital market.It uses three methods:parallel trend and dynamic testing,PSM-DID analysis,and placebo testing for robustness testing to solve the endogeneity problem of the experiment.This article also conducts deeper research on the subject based on the two dimensions of the impact mechanism of margin financing and securities lending and the size of the company,and finally discusses the economic impact of margin financing and securities lending on the level of company innovation.

A contention-based efficient-information perception algorithm (CEiPA) for vehicular ad hoc networks

The problem of information dissemination is researched for vehicular ad-hoc networks （VANET） in this paper, and a contention-based effficient-information perception algorithm （CEiPA） is proposed. The idea of CEiPA is that beacons are delivered over VANET with limited lifetime and efficient information. CEiPA consists of two phases. The first one is initialization phase, during which the count timers Tcyce and Tlocal are set to start beacon delivery while Tcycle is also used to monitor and restart beaconing. The second one is beacon delivery phase. An elaborate distance function is employed to set contention delay for beacons of each vehicle. In this way beacons will be sent in order, which decreases the collision of beacons. Simulation results show that CEiPA enables each beacon to carry more efficient information and spread them over more vehicles with lower network overhead than the periodic beacon scheme. CEiPA is also flexible and scalable because the efficient information threshold it employs is a balance among the freshness of information, network overhead and perception area of a vehicle.

An Efficient CSI Feedback Scheme for Dual-Polarized MIMO Systems Using Layered Multi-Paths Information

Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However, current CSI（channel state information） feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover, the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback （LMPIF）, which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components （multipath directions and amplitudes） and short term components （multipath phases）. The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead, different granularities in feedback time have been applied for the long term components and short term components Link and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.

Methods for the Efficient Energy Management in a Smart Mini Greenhouse

To solve the problem of energy efficiency of modern enterprise it is necessary to reduce energy consumption.One of the possible ways is proposed in this research.A multi-level hierarchical system for energy efficiency management of the enterprise is designed,it is based on the modular principle providing rapid modernization.The novelty of the work is the development of new and improvement of the existing methods and models,in particular:1)models for dynamic analysis of IT tools for data acquisition and processing(DAAP)in multilevel energy management systems,which are based on Petri nets;2)method of synthesis of DAAP tools in energy efficiency management information systems(EEMIS)of the enterprise which provides a reduction in hardware and time costs from 10%to 40%;3)method of conflict-free data exchange determining the minimum memory speed for the synthesis of realtime exchanges,it reduces the cost and energy consumption;4)method of calculating the signal of postsynaptic excitation of neural elements decreases the processing time of technological data two or more times.The proposed methods,models and tools have been tested while implementing the EEMIS of the intelligent mini-greenhouse,as a result,energy efficiency has increased by 12%-25%(depending on season and peculiarities of growing plants).

Adaptive Energy-Efficient Power Allocation for DAS with Imperfect Channel State Information and Antenna Selection

Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.