The SEALS Yardsticks for Ontology Management

This paper describes the rst SEALS evaluation campaign over ontology engineering tools (i.e., the SEALS Yardsticks for Ontology Management). It presents the dierent evaluation scenarios dened to evaluate the conformance, interoperability and scalability of these tools, and the test data used in these scenarios

Speeding up liquid crystal SLMs using overdrive with phase change reduction

Nematic liquid crystal spatial light modulators (SLMs) with fast switching times and high diffraction efficiency are important to various applications ranging from optical beam steering and adaptive optics to optical tweezers. Here we demonstrate the great benefits that can be derived in terms of speed enhancement without loss of diffraction efficiency from two mutually compatible approaches. The first technique involves the idea of overdrive, that is the calculation of intermediate patterns to speed up the transition to the target phase pattern. The second concerns optimization of the target pattern to reduce the required phase change applied to each pixel, which in addition leads to a substantial reduction of variations in the intensity of the diffracted light during the transition. When these methods are applied together, we observe transition times for the diffracted light fields of about 1 ms, which represents up to a tenfold improvement over current approaches. We experimentally demonstrate the improvements of the approach for applications such as holographic image projection, beam steering and switching, and real-time control loops

Dyadic existential rules

In the field of ontology-based query answering, existential rules (a.k.a. tuple-generating dependencies) form an expressive Datalog-based language to specify implicit knowledge. The presence of existential quantification in rule-heads, however, makes the main reasoning tasks undecidable. To overcome this limitation, in the last two decades, a number of classes of existential rules guaranteeing the decidability of query answering have been proposed. Unfortunately, such classes are typically based on different syntactic conditions imposing the development of different ad hoc reasoners. This paper introduces a novel general condition that allows to define, systematically, from any decidable class C of existential rules, a new class called Dyadic-C that enjoys the following properties: (i) it is decidable; (ii) it generalizes C; (iii) it keeps the same data complexity as C; and (iv) it can exploit any reasoner for query answering over C. Additionally, the paper proposes a simple and elegant syntactic condition that gives rise to the class Ward+ generalizing the well-known decidable classes Shy and Ward, and being included in Dyadic-Shy

The effects of rolling resistance on the stress-strain and strain localization behavior of granular materials due to simple shear loading conditions.

The previous studies has conclusively shown that rolling resistance is a significant parameter influencing the stress-strain and strain localization response of granular materials when a failure state can be reached in biaxial test with small strain, (2-4%) of axial strain [1, 2]. However, in order to allow for larger deformations, numerical experiments are carried out for a simple shear test. In these simulations strain localization can be obtained for relatively high shear strain. The main objective of this paper is to present the results of a comprehensive study using DEM modeling of the effects of the variation in rolling resistance on the elasticity, shear strength, dilation and bifurcation response of granular materials subjected to simple shear loading. A comprehensive parametric study is performed whereby the magnitude of rolling resistance is varied within its full range of possible values in conjunction with variations in other model parameters, and more practically to interpret the macroscopic behavior of granular specimens subjected to different loading conditions from the viewpoint of micromechanics

Optomechanical deformation and strain in elastic dielectrics

Light forces induced by scattering and absorption in elastic dielectrics lead to local density modulations and deformations. These perturbations in turn modify light propagation in the medium and generate an intricate nonlinear response. We generalise an analytic approach where light propagation in one-dimensional media of inhomogeneous density is modelled as a result of multiple scattering between polarizable slices. Using the Maxwell stress tensor formalism we compute the local optical forces and iteratively approach self-consistent density distributions where the elastic back-action balances gradient- and scattering forces. For an optically trapped dielectric we derive the nonlinear dependence of trap position, stiffness and total deformation on the object's size and field configuration. Generally trapping is enhanced by deformation, which exhibits a periodic change between stretching and compression. This strongly deviates from qualitative expectations based on the change of photon momentum of light crossing the surface of a dielectric. We conclude that optical forces have to be treated as volumetric forces and that a description using the change of photon momentum at the surface of a medium is inappropriate

Orbital angular momentum exchange in an optical parametric oscillator

We present a study of orbital angular momentum transfer from pump to down-converted beams in a type-II Optical Parametric Oscillator. Cavity and anisotropy effects are investigated and demostrated to play a central role in the transverse mode dynamics. While the idler beam can oscillate in a Laguerre-Gauss mode, the crystal birefringence induces an astigmatic effect in the signal beam that prevents the resonance of such mode.Comment: 10 pages, 8 figures, regular articl

The history of the pediatric inguinal hernia repair

The history of inguinal hernia repair is a rich one. For centuries, hernia healers, doctors, anatomists, surgeons and quacks have been devoted to this pathology that has afflicted mankind throughout its evolution. The development of surgical correction mainly focused on adult pathology, with treatments that often involved the loss of the testis. Hernia management in children, however, also dates from antiquity. Described as a swelling on the surface of the belly in ancient papyri, it was treated with tight bandages by the early physicians of Alexandria. For centuries, conservative treatment had been used for the child using primordial trussess, many prayers, and often pagan rituals as the arboreal passage of children described by Marcello of Bordeaux, doctor of the Emperor Theodosius I (347-395 AD), reserving medical intervention only for cases of strangulation in which only reduction was attempted. The middle ages were characterized by an increase in cultural and scientific exchange, during which the first comprehensive surgical textbooks and atlases were written. Different approaches to the inguinal hernia were not taught and passed down through generations of surgeons. The modern era brought a better understanding of the inguinal anatomy, which led to surgical techniques associated with less post-operative complications. Today, the pediatric inguinal hernia repair is one of the most common pediatric operations performed. It is considered a safe procedure with very low complication rate

Digital skills critical for education: Video analysis of students' technology use in Norwegian secondary English classrooms

Background: Globally, digital skills are a crucial aspect of education that schoolsshould develop systematically. Research on digital skills tends to be measured usingself-reports, performance tests or interventions. There is less knowledge about stu-dent and teacher uptake of technology in school, making it important to investigatethe actual use of technology and digital skills in authentic classroom settings. Objectives:This study contributes unique baseline data concerning students' use oftechnology and digital skills across mandatory English courses in real classroom set-tings in secondary schools in Norway over time. Methods:The study adapted a national framework for digital skills into an observa-tion protocol. With it, this study analysed videos from 60 naturally occurring Englishlessons in 13 English classes at seven lower secondary schools over two school years(grades 9 and 10), following 186 students (aged 13–15) and 10 teachers. Results and Conclusions:Students used digital skills critical for education in half ofthe video-recorded English lessons, with more digital skill use at some schools overtime. The main finding across classrooms and school years regards students' use ofbasic, not advanced, digital skills. Takeaways:Although teachers provide opportunities for students to use digital skillsin school, more advanced skills are needed. This work calls for continued use of videorecordings to provide systematic comparisons of potential shifts in students' digitalskills in real English secondary classroom settings over time.publishedVersio

Mode hopping strongly affects observability of dynamical instability in optical parametric oscillators

Theoretical investigations of dynamical behavior in optical parametric oscillators (OPO) have generally assumed that the cavity detunings of the interacting fields are controllable parameters. However, OPOs are known to experience mode hops, where the system jumps to the mode of lowest cavity detuning. We note that this phenomenon significantly limits the range of accessible detunings and thus may prevent instabilities predicted to occur above a minimum detuning from being evidenced experimentally. As a simple example among a number of instability mechanisms possibly affected by this limitation, we discuss the Hopf bifurcation leading to periodic behavior in the monomode mean-field model of a triply resonant OPO and show that it probably can be observed only in very specific setups.Comment: submitted to Phys. Rev.