The periodic health examination: a useless test?

A critical analysis of the theoretical concepts applying to mass screening (Frames' criteria) in relation with the "Evidence-Based Medicine" methodology leads to rule out the basic blood test from the periodic health examination. A good questioning with a good clinical examination will select high risk populations for specific health problems for which some oriented tests can be performed with an acceptable positive predictive value.     

Design of small hand‐launched solar‐powered UAVs: From concept study to a multi‐day world endurance record flight

We present the development process behind AtlantikSolar, a small 6.9 kg hand‐launchable low‐altitude solar‐powered unmanned aerial vehicle (UAV) that recently completed an 81‐hour continuous flight and thereby established a new flight endurance world record for all aircraft below 50 kg mass. The goal of our work is to increase the usability of such solar‐powered robotic aircraft by maximizing their perpetual flight robustness to meteorological deteriorations such as clouds or winds. We present energetic system models and a design methodology, implement them in our publicly available conceptual design framework for perpetual flight‐capable solar‐powered UAVs, and finally apply the framework to the AtlantikSolar UAV. We present the detailed AtlantikSolar characteristics as a practical design example. Airframe, avionics, hardware, state estimation, and control method development for autonomous flight operations are described. Flight data are used to validate the conceptual design framework. Flight results from the continuous 81‐hour and 2,338 km covered ground distance flight show that AtlantikSolar achieves 39% minimum state‐of‐charge, 6.8 h excess time and 6.2 h charge margin. These performance metrics are a significant improvement over previous solar‐powered UAVs. A performance outlook shows that AtlantikSolar allows perpetual flight in a 6‐month window around June 21 at mid‐European latitudes, and that multi‐day flights with small optical‐ or infrared‐camera payloads are possible for the first time. The demonstrated performance represents the current state‐of‐the‐art in solar‐powered low‐altitude perpetual flight performance. We conclude with lessons learned from the three‐year AtlantikSolar UAV development process and with a sensitivity analysis that identifies the most promising technological areas for future solar‐powered UAV performance improvements.     

Topic discovery and evolution in scientific literature based on content and citations

Researchers across the globe have been increasingly interested in the manner in which important research topics evolve over time within the corpus of scientific literature. In a dataset of scientific articles, each document can be considered to comprise both the words of the document itself and its citations of other documents. In this paper, we propose a citation- content-latent Dirichlet allocation (LDA) topic discovery method that accounts for both document citation relations and the con-tent of the document itself via a probabilistic generative model. The citation-content-LDA topic model exploits a two-level topic model that includes the citation information for ‘father’ topics and text information for sub-topics. The model parameters are estimated by a collapsed Gibbs sampling algorithm. We also propose a topic evolution algorithm that runs in two steps: topic segmentation and topic dependency relation calculation. We have tested the proposed citation-content-LDA model and topic evolution algorithm on two online datasets, IEEE Transactions on Pattern Analysis and Machine Intelligence (PAMI) and IEEE Computer Society (CS), to demonstrate that our algorithm effectively discovers important topics and reflects the topic evolution of important research themes. According to our evaluation metrics, citation-content-LDA outperforms both content-LDA and citation-LDA.     

Time-constrained services: a framework for using real-time web services in industrial automation

The use of web services in industrial automation, e.g. in fully automated production processes like car manufacturing, promises simplified interaction among the manufacturing devices due to standardized protocols and increased flexibility with respect to process implementation and reengineering. Moreover, the adoption of web services as a seamless communication backbone within the overall industrial enterprise has additional benefits, such as simplified interaction with suppliers and customers (i.e. horizontal integration) and avoidance of a break in the communication paradigm within the enterprise (i.e. vertical integration). The Time-Constrained Services (TiCS) framework is a development and execution environment that empowers automation engineers to develop, deploy, publish, compose, and invoke time-constrained web services. TiCS consists of four functional layers—tool support layer, real-time infrastructural layer, real-time service layer, and hardware layer—which contain several components to meet the demands of a web service based automation infrastructure. This article gives an overview of the TiCS framework. More precisely, the general design considerations and an architectural blueprint of the TiCS framework are presented. Subsequently, selected key components of the TiCS framework are discussed in detail: the SOAP4PLC engine for equipping programmable logic controllers with a web service interface, the SOAP4IPC engine for processing web services in real-time on industrial PCs, the WS-TemporalPolicy language for describing time constraints, and the TiCS Modeler for composing time-constrained web services into a time-constrained BPEL4WS workflow.     

Reinforcement learning for robot soccer

Batch reinforcement learning methods provide a powerful framework for learning efficiently and effectively in autonomous robots. The paper reviews some recent work of the authors aiming at the successful application of reinforcement learning in a challenging and complex domain. It discusses several variants of the general batch learning framework, particularly tailored to the use of multilayer perceptrons to approximate value functions over continuous state spaces. The batch learning framework is successfully used to learn crucial skills in our soccer-playing robots participating in the RoboCup competitions. This is demonstrated on three different case studies.

A ‘No Panacea Theorem’ for classifier combination

We introduce the ‘No Panacea Theorem’ (NPT) for multiple classifier combination, previously proved only in the case of two classifiers and two classes. In this paper, we extend the NPT to cases of multiple classifiers and multiple classes. We prove that if the combination function is continuous and diverse, there exists a situation in which the combination algorithm will give very bad performance. The proof relies on constructing ‘pathological’ probability density distributions that have high densities in particular areas such that the combination functions give incorrect classification. Thus, there is no optimal combination algorithm that is suitable in all situations. It can be seen from this theorem that the probability density functions (pdfs) play an important role in the performance of combination algorithms, so studying the pdfs becomes the first step of finding a good combination algorithm. Although devised for classifier combination, the NPT is also relevant to all supervised classification problems.     

Broadband slat noise prediction based on CAA and stochastic sound sources from a fast random particle-mesh (RPM) method

The application of a low-cost computational aeroacoustics (CAA) approach to a slat noise problem is studied. A fast and efficient stochastic method is introduced to model the unsteady turbulent sound sources in the slat-cove of a high-lift airfoil. It is based on the spatial convolution of spatiotemporal white-noise and can reproduce target distributions of turbulence kinetic energy and length scales, such as that provided by a RANS computation of the time-averaged turbulent flow problem. The computational method yields a perfectly solenoidal velocity field. For homogeneous isotropic turbulence, the complete second-order two-point velocity correlation tensor is realized exactly. Two RANS turbulence models are applied to the slat noise problem to study how sensitive the aeroacoustics predictions depend on turbulence kinetic energy predictions. Results for the sound generation at the slat are given for a Menter SST turbulence model with and without Kato-Launder modification. The aeroacoustic simulations yield a characteristic narrow band spectrum that compares very well with the experimental data. The directivities found point toward an edge noise mechanism at the slat as the main cause for slat noise sound generation.     

Should learners use their hands for learning? Results from an eye-tracking study

Given the widespread use of touch screen devices, the effect of the users' fingers on information processing and learning is of growing interest. The present study drew on cognitive load theory and embodied cognition perspectives to investigate the effects of pointing and tracing gestures on the surface of a multimedia learning instruction. Learning performance, cognitive load and visual attention were examined in a one-factorial experimental design with the between-subject factor pointing and tracing gestures. The pointing and tracing group were instructed to use their fingers during the learning phase to make connections between corresponding text and picture information, whereas the control group was instructed not to use their hands for learning. The results showed a beneficial effect of pointing and tracing gestures on learning performance, a significant shift in visual attention and deeper processing of information by the pointing and tracing group, but no effect on subjective ratings of cognitive load. Implications for future research and practice are discussed.     

Influence of long-range and strong correlation effects on the electron-phonon coupling in high-Tc oxides

Calculations of the Eliashberg function ²F and the corresponding transport function _tr ² F for high-T _c oxides are presented using a screened ionic model (rigidly shifted ionic potentials screened by charge carriers in the CuO₂ planes within the RPA) for the electron-phonon coupling. It is shown that this model yields a large difference between the transport and the superconducting electron-phonon interaction due to imperfect screening and contributions beyond nearest-neighbor interactions. Using these results, the electron and the lattice heat conductivities are calculated both in the normal and the superconducting state and compared with experiment. Finally, effects due to a strong on-site electron-electron repulsion are included in leading order in an 1/N expansion, whereN is the number of spin degrees of freedom. In particular, it is shown for the infiniteU, one-band Hubbard model that correlations tend to suppress _tr ² F strongly and ² F somewhat.The author thanks M. Kulic for discussions and cooperation on the topic discussed in Section 4.     

Phonon Polaritons in Monolayers of Hexagonal Boron Nitride

Phonon polaritons in van der Waals materials reveal significant confinement accompanied with long propagation length: important virtues for tasks pertaining to the control of light and energy flow at the nanoscale. While previous studies of phonon polaritons have relied on relatively thick samples, here reported is the first observation of surface phonon polaritons in single atomic layers and bilayers of hexagonal boron nitride (hBN). Using antenna‐based near‐field microscopy, propagating surface phonon polaritons in mono‐ and bilayer hBN microcrystals are imaged. Phonon polaritons in monolayer hBN are confined in a volume about one million times smaller than the free‐space photons. Both the polariton dispersion and their wavelength–thickness scaling law are altered compared to those of hBN bulk counterparts. These changes are attributed to phonon hardening in monolayer‐thick crystals. The data reported here have bearing on applications of polaritons in metasurfaces and ultrathin optical elements.