Threshold-free Evaluation of Medical Tests for Classification and Prediction: Average Precision versus Area Under the ROC Curve

When evaluating medical tests or biomarkers for disease classification, the area under the receiver-operating characteristic (ROC) curve is a widely used performance metric that does not require us to commit to a specific decision threshold. For the same type of evaluations, a different metric known as the average precision (AP) is used much more widely in the information retrieval literature. We study both metrics in some depths in order to elucidate their difference and relationship. More specifically, we explain mathematically why the AP may be more appropriate if the earlier part of the ROC curve is of interest. We also address practical matters, deriving an expression for the asymptotic variance of the AP, as well as providing real-world examples concerning the evaluation of protein biomarkers for prostate cancer and the assessment of digital versus film mammography for breast cancer screening.Comment: The first two authors contributed equally to this paper, and should be regarded as co-first author

Spin Current and Current-Induced Spin Transfer Torque in Ferromagnet-Quantum Dot-Ferromagnet Coupled Systems

Based on Keldysh's nonequilibrium Green function method, the spin-dependent transport properties in a ferromagnet-quantum dot (QD)-ferromagnet coupled system are investigated. It is shown the spin current shows quite different characteristics from its electrical counterpart, and by changing the relative orientation of both magnetizations, it can change its magnitude even sign. The current-induced spin transfer torque (CISTT) is uncovered to be greatly enhanced when the bias voltage meets with the discrete levels of the QD at resonant positions. The relationship between the CISTT, the electrical current and the spin current is also addressed.Comment: 21 pages, 8 figure

Recognition of 3D arm movements using neural networks

[[abstract]]There are many different approaches to recognition of spatio-temporal patterns. Each has its own merits and disadvantages. In this paper we present a neural-network-based approach to spatio-temporal pattern recognition. The effectiveness of this method is evaluated by recognizing 3D arm movements involved in Taiwanese sign language (TSL).[[conferencetype]]國際[[conferencedate]]19990710~19990716[[booktype]]紙本[[conferencelocation]]Washington, DC, US

Rule extraction using a novel class of fuzzy degraded hyperellipsoidal composite neural networks

[[abstract]]Presents an innovative approach to rule extraction directly from experimental numerical data for system identification. The authors discuss how to use a novel class of fuzzy degraded hyperellipsoidal composite neural networks (FDHECNN's) to extract fuzzy if-then rules. The fuzzy rules are defined by hyperellipsoids of which principal axes are parallel to the coordinates of the input space. These rules are extracted from the parameters of the trained FDHECNN's. Based on a special learning scheme, the FDHECNN's can evolve automatically to acquire a set of fuzzy rules for approximating the input/output functions considered systems. A highly nonlinear system is used to test the proposed neuro-fuzzy systems.[[conferencetype]]國際[[conferencedate]]19950320~19950324[[conferencelocation]]Yokohama, Japa

Boosting Reinforcement Learning and Planning with Demonstrations: A Survey

Although reinforcement learning has seen tremendous success recently, this kind of trial-and-error learning can be impractical or inefficient in complex environments. The use of demonstrations, on the other hand, enables agents to benefit from expert knowledge rather than having to discover the best action to take through exploration. In this survey, we discuss the advantages of using demonstrations in sequential decision making, various ways to apply demonstrations in learning-based decision making paradigms (for example, reinforcement learning and planning in the learned models), and how to collect the demonstrations in various scenarios. Additionally, we exemplify a practical pipeline for generating and utilizing demonstrations in the recently proposed ManiSkill robot learning benchmark

An Empirical Research on Hotel Revenue Management Financial Performance Influencing Factors

In recent years, revenue management has become an important competitive strategy in the hotel, and the level of hotel performance directly reflects the effectiveness of the application of revenue management. But so far, academic research about hotel revenue management performance influencing mechanism and evaluation is still extremely limited. Based on fully retrieving the relevant literature, the author summarized the factors affecting revenue management financial performance and built a conceptual model, using structural equation model (SEM) to verify and correct it. Then the author concluded: hotel quality attributes which contain hotel scale, star rating, owner type and management company type have no significant effect on hotel revenue management performance; technical drivers which include pricing and non-pricing factors have significant positive impact on RM performance, and the impact of pricing tools is more intense; organizational drivers including organizational support, manager quality, incentive and training have positive impact on RM performance, second only to pricing tools; and finally, organizational drivers had significant impact on technical drivers

Hotel Revenue Management Performance Influencing Mechanism: Theoretical Framework and Research Propositions

Revenue management, a management concept which was first used in the US airline industry and has been widely used in other service industries especially hotel industry because of the significant effect. Especially in recent years, revenue management has become an important competition strategy in the hotel. But so far, academic research about hotel revenue management influence mechanism and performance evaluation is still extremely limited. Based on the influencing factors-decision behavior-performance evaluation logical relationship, combing through the literature review, this paper discussed the relationship between revenue management influence factors and the performance evaluation, proposed the theory framework concerning influence mechanism of hotel revenue management performance evaluation and research propositions

Spin-Polarized Transport in Ferromagnet-Marginal Fermi Liquid Systems

Spin-polarized transport through a marginal Fermi liquid (MFL) which is connected to two noncollinear ferromagnets via tunnel junctions is discussed in terms of the nonequilibrium Green function approach. It is found that the current-voltage characteristics deviate obviously from the ohmic behavior, and the tunnel current increases slightly with temperature, in contrast to those of the system with a Fermi liquid. The tunnel magnetoresistance (TMR) is observed to decay exponentially with increasing the bias voltage, and to decrease slowly with increasing temperature. With increasing the coupling constant of the MFL, the current is shown to increase linearly, while the TMR is found to decay slowly. The spin-valve effect is observed.Comment: 5 pages, 6 figures, Phys. Rev. B 71, 064412 (2005