Secrecy sum rate maximization in non-orthogonal multiple access

Non-orthogonal multiple access (NOMA) has been recognized as a promising technique for providing high data rates in 5G systems. This letter is to study physical layer security in a single-input single-output (SISO) NOMA system consisting of a transmitter, multiple legitimate users and an eavesdropper. The aim of this letter is to maximize the secrecy sum rate (SSR) of the NOMA system subject to the users' quality of service (QoS) requirements. We firstly identify the feasible region of the transmit power for satisfying all users' QoS requirements. Then we derive the closed-form expression of an optimal power allocation policy that maximizes the SSR. Numerical results are provided to show a significant SSR improvement by NOMA compared with conventional orthogonal multiple access (OMA)

Distributional effects of carbon taxation

The carbon tax is a frequently discussed economic instrument for carbon emissions mitigation and prevention of global climate change. However, a range of issues may emerge when introducing a carbon tax; among these issues, the distributional impact has been frequently highlighted as an obstacle to the public acceptance of such a mitigation policy. This literature review focuses specifically on the distributional effects of carbon taxes and contributes to existing studies by providing a classification and discussion on how to comprehensively assess distributional impacts and what measures can be taken to mitigate the potential adverse distributional impact We confirm that a pure carbon tax without revenue recycling in developed economies tends to be regressive, i.e. lower income households being more affected, while our research does not support the perception that it reveals progressivity in developing countries. In terms of its effects on economic sectors, we find that sectors with higher energy intensity are more affected by a uniform carbon tax, while preferential measures to protect these industries face a trade-off between environmental effectiveness and economic growth. We also stress that different designs for carbon tax mechanisms play a key role in affecting the distributional impacts and impacts in other policy arenas, indicating that trade-offs between efficiency and equity always exist when designing a carbon tax. This study may help to identify the shortcomings of existing designs and puts forward practical implications for future research; moreover, it offers valuable information to help policy-makers to understand the trade-off between equity and efficiency when designing a carbon tax. (C) 2016 Published by Elsevier Ltd

Dietary plant soot supplementation improves the intestinal health status of farmed American eels (<em>Anguilla rostrata</em>)

The current study evaluated the effect of different dietary plant soot supplementation levels on the intestinal health status of American eels (Anguilla rostrata) cultured in concrete tanks. Nine concrete fish tanks were randomly divided into three groups and fed the diets with plant soot (PS) supplementation levels at 0, 3 g/kg, and 5 g/kg, respectively. After a feeding trial for 60 days, the intestinal tissues were sampled to measure health status parameters. The D-lactate level and DAO activity in the serum of the PS5 group were significantly lower than those of the PS0 group (P <0.05). Compared with the PS0 group, the villi length of the intestine in both PS3 group and PS5 group increased significantly (P<0.05). The muscular thickness of the intestine of the PS5 group was significantly higher than the PS0 group (P<0.05). The microvillus density of the intestine of the American eel was increased obviously in the PS5 group. The intestinal microbiota composition of plant soot groups was beneficially regulated with certain probiotics' higher relative abundances and some pathogenic bacteria' lower relative abundance. In conclusion, dietary 5 g/kg plant soot supplementation could benefit the intestinal health of farmed American eels