Orthogonal invariant sets of the diffusion tensor and the development of a curvilinear set suitable for low-anisotropy tissues.

We develop a curvilinear invariant set of the diffusion tensor which may be applied to Diffusion Tensor Imaging measurements on tissues and porous media. This new set is an alternative to the more common invariants such as fractional anisotropy and the diffusion mode. The alternative invariant set possesses a different structure to the other known invariant sets; the second and third members of the curvilinear set measure the degree of orthotropy and oblateness/prolateness, respectively. The proposed advantage of these invariants is that they may work well in situations of low diffusion anisotropy and isotropy, as is often observed in tissues such as cartilage. We also explore the other orthogonal invariant sets in terms of their geometry in relation to eigenvalue space; a cylindrical set, a spherical set (including fractional anisotropy and the mode), and a log-Euclidean set. These three sets have a common structure. The first invariant measures the magnitude of the diffusion, the second and third invariants capture aspects of the anisotropy; the magnitude of the anisotropy and the shape of the diffusion ellipsoid (the manner in which the anisotropy is realised). We also show a simple method to prove the orthogonality of the invariants within a set

Mixed-State Entanglement and Quantum Teleportation through Noisy Channels

The quantum teleportation with noisy EPR state is discussed. Using an optimal decomposition technique, we compute the concurrence, entanglement of formation and Groverian measure for various noisy EPR resources. It is shown analytically that all entanglement measures reduce to zero when $\bar{F} \leq 2/3$, where $\bar{F}$ is an average fidelity between Alice and Bob. This fact indicates that the entanglement is a genuine physical resource for the teleportation process. This fact gives valuable clues on the optimal decomposition for higher-qubit mixed states. As an example, the optimal decompositions for the three-qubit mixed states are discussed by adopting a teleportation with W-stateComment: 18 pages, 4 figure

A study on the key performance indicator of the dynamic positioning system

AbstractThe dynamic positioning system (DPS) maintains an offshore vessel's position and heading under various environmental conditions by using its own thrust. DPS is regarded as one of the most important systems in offshore vessels. So, efficient operation and maintenance of the DPS are important issues. To monitor the DPS, it is necessary to define an appropriate key performance indicator (KPI) that can express the condition of the DPS from the perspective of operational efficiency and maintenance. In this study, a new KPI for the DPS is proposed considering the efficiency of the machinery and controller, the energy efficiency, and the environmental conditions in which the DPS is operated. The KPI is defined as a function of control deviation, energy consumption, and environmental load. A normalization factor is used to normalize the effect of environmental load on the KPI. The KPI value is calculated from DPS simulation and model test data. The possibility of applying the KPI to monitoring of DPS condition is discussed by comparing the values. The result indicates the feasibility of the new KPI

Combination of sugar-sweetened beverage consumption, screen-based sedentary time, and sleep duration and their association with South Korean adolescents' mental health

IntroductionThis study examines the combinations of sugar-sweetened beverage (SSB) consumption, screen-based sedentary time, and sleep duration and their association with adolescents' depressive symptoms and suicidal ideation.MethodsThis research followed a crosssectional study design. Secondary data analysis was conducted on the data collected from 21,046 high school students who had participated in the 17th Korea Youth Risk Behavior Web-Based Survey in 2021. A complex sampling analysis, including descriptive and logistic regression analyses, was conducted in SPSS Statistics 26.0.ResultsThe combination of low SSB consumption, excessive screen-based sedentary time, and short sleep duration was associated with an increase in depressive symptoms. In addition, a combination of medium/high SSB consumption, appropriate/excessive screen-based sedentary time, and short sleep duration was associated with an increase in depressive symptoms. Finally, the combination of high SSB consumption, excessive screen-based sedentary time, and short sleep duration was associated with an increase in suicidal ideation.DiscussionThe findings demonstrate that healthcare providers should develop and conduct family-and school-based programs to restrict SSB consumption, screen-based sedentary behaviors, and sleep duration to improve adolescents' mental health