Comment on: Stochastic local operations and classical communication Invariant and the residual entanglement for n qubits

In a recent paper [Phys. Rev. A 76, 032304(2007)], Li et al. proposed the definition of the residual entanglement for n qubits by means of the Stochastic local operations and classical communication. Here we argue that their definition is not suitable for the case of odd-n qubits.Comment: 3 pages, submitted to PR

Deformable Groupwise Registration Using a Locally Low-Rank Dissimilarity Metric for Myocardial Strain Estimation from Cardiac Cine MRI Images

Objective: Cardiovascular magnetic resonance-feature tracking (CMR-FT) represents a group of methods for myocardial strain estimation from cardiac cine MRI images. Established CMR-FT methods are mainly based on optical flow or pairwise registration. However, these methods suffer from either inaccurate estimation of large motion or drift effect caused by accumulative tracking errors. In this work, we propose a deformable groupwise registration method using a locally low-rank (LLR) dissimilarity metric for CMR-FT. Methods: The proposed method (Groupwise-LLR) tracks the feature points by a groupwise registration-based two-step strategy. Unlike the globally low-rank (GLR) dissimilarity metric, the proposed LLR metric imposes low-rankness on local image patches rather than the whole image. We quantitatively compared Groupwise-LLR with the Farneback optical flow, a pairwise registration method, and a GLR-based groupwise registration method on simulated and in vivo datasets. Results: Results from the simulated dataset showed that Groupwise-LLR achieved more accurate tracking and strain estimation compared with the other methods. Results from the in vivo dataset showed that Groupwise-LLR achieved more accurate tracking and elimination of the drift effect in late-diastole. Inter-observer reproducibility of strain estimates was similar between all studied methods. Conclusion: The proposed method estimates myocardial strains more accurately due to the application of a groupwise registration-based tracking strategy and an LLR-based dissimilarity metric. Significance: The proposed CMR-FT method may facilitate more accurate estimation of myocardial strains, especially in diastole, for clinical assessments of cardiac dysfunction

Numerical modeling on the seismic responses of a large underground structure in soft ground

To estimate the earthquake damages of a large subway station built in soft ground, a soil-underground structure static and dynamic coupling interaction model is advanced with the strong nonlinear properties of soil modeled by a developed viscous-plastic constitutive model. The numerical modeling results show that the large underground structure in soft site has a large vertical relative deformation during the horizontal earthquake, which could be larger than its horizontal relative deformation. The dynamic deformation responses of the components near to the middle span of the underground structure are obviously larger those of the other components at the side spans, which means that these components near to the middle span are more apt to be damaged in horizontal earthquake. According to the horizontal relative deformation and the seismic damage process of the large underground structure, which limited elastic working state and the limited elastic-plastic working state are determined, and the maximal interlayer displacement angles are suggested to be 1/430 for the limited elastic working state and 1/185 for the limited elastic-plastic working state. In addition, the seismic soil pressure coefficients on the upper side wall have significant changes. To the large underground structure shown in this paper, the seismic soil pressure coefficients on the top half of the upper side wall should be defined alone in its seismic design

Chinese university students' awareness and attitudes towards forest based bioenergy

Forest biomass is considered as one of the most important alternative energy sources across the globe. Growing attention has been given to the studies concerning biomass and related bioenergy and biofuel, and their potential for future development. This study takes higher education as unique aspect, focusing on the awareness of Chinese university students of Forest Based Bioenergy (FBB) development and how education background / awareness may influence the FBB development in China. Since FBB is relatively a new concept in China, its development and further utilization are believed to largely relay on the matters of education, social trend and awareness. Students in higher education are considered as a special group: they may be educated related to FBB and will become the future consumers and even decision-makers. This make awareness, attitude and opinions about FBB from the students` point of view significant. A literature review was made for the background study and quantitative research, plus surveys and interviews were conducted as data collection methods. Objectives of the thesis are to study the awareness of and attitudes towards FBB among Chinese university students and if those opinions were influenced by their studies. Results indicate that education strongly affects students´ attitudes. FBB development is seen as a positive signal and students are likely to support FBB development. FBB is believed as a new trend of renewable energy development. However, FBB in China will not see a rapid booming in the near future and it has only limited impact towards the traditional fossil fuel domination, but due to its characteristics, governmental recognition and growing awareness, it certainly shall be seen as strong supporter of China´s sustainable development. It also has to be holistically utilized considering environmental, social and economic aspects, to reach its full potential and to support China´s target of sustainable energy development

Security and Energy-aware Collaborative Task Offloading in D2D communication

Device-to-device (D2D) communication technique is used to establish direct links among mobile devices (MDs) to reduce communication delay and increase network capacity over the underlying wireless networks. Existing D2D schemes for task offloading focus on system throughput, energy consumption, and delay without considering data security. This paper proposes a Security and Energy-aware Collaborative Task Offloading for D2D communication (Sec2D). Specifically, we first build a novel security model, in terms of the number of CPU cores, CPU frequency, and data size, for measuring the security workload on heterogeneous MDs. Then, we formulate the collaborative task offloading problem that minimizes the time-average delay and energy consumption of MDs while ensuring data security. In order to meet this goal, the Lyapunov optimization framework is applied to implement online decision-making. Two solutions, greedy approach and optimal approach, with different time complexities, are proposed to deal with the generated mixed-integer linear programming (MILP) problem. The theoretical proofs demonstrate that Sec2D follows a [O(1∕V),O(V)] energy-delay tradeoff. Simulation results show that Sec2D can guarantee both data security and system stability in the collaborative D2D communication environment