User study on 3D multitouch interaction (3DMi) and gaze on surface computing

On a multitouch table, user’s interactions with 3D virtual representations of real objects should be influenced by task and their perceived physical characteristics. This article explores the development and user study of an interactive 3D application that allows users to explore virtual heritage objects on a surface device. To-date, most multitouch has focused on 2D or 2.5D systems. A user-study is reported where we analyse their multimodal behaviour – specifically how they interact on a surface device with objects that have similar properties to physical versions and the users’ associated gaze patterns with touch. The study reveals that gaze characteristics are different according to their interaction intention in terms of position and duration of visual attention. We discovered that virtual objects afford the perception of haptic attributes ascribed to their equivalent physical objects, and that differences in the summary statistics of gaze showed consistent characteristics between people and differences between natural and task based activities. An awareness of user behaviours using natural gestures can inform the design of interactive 3D applications which complements the user’s model of past experience with physical objects and with GUI interaction

Fractal Scales in a Schwarzschild Atmosphere

Recently, Glass and Krisch have extended the Vaidya radiating metric to include both a radiation fluid and a string fluid [1999 Class. Quantum Grav. vol 16, 1175]. Mass diffusion in the extended Schwarzschild atmosphere was studied. The continuous solutions of classical diffusive transport are believed to describe the envelope of underlying fractal behavior. In this work we examine the classical picture at scales on which fractal behavior might be evident.Comment: to appear in Class. Quantum Gra

Effect of Polyurethane Viscosity on Self-Healing Efficiency of Cementitious Materials Exposed to High Temperatures from Sun Radiation

Insulated concrete elements used in building facades, e.g.,sandwich panels, are frequently exposed to sun radiation, which causes high temperatures on the outside. Although the inner and outer cladding are supposed to be independent, a high temperature difference between the outside and the inside of the elements causes thermal bending, which can lead to cracking. These cracks may have an impact on the durability of the outer cladding and are not wanted from an esthetic point of view. A possible solution for this problem is the embedment of encapsulated polyurethane in the concrete matrix in order to repair cracks autonomously. However, healing agents with suitable properties are needed to heal cracks at these conditions. In this research, newly developed polyurethane resins with relatively high viscosity were tested for their healing efficiency at high temperatures. The mechanical properties of the polyurethanes such as bond strength and elasticity were determined. Second, the healing agents were encapsulated and evaluated for their efficiency to heal cracks by capillary absorption tests, strength regain evaluation, and X-ray computed tomography. The new polyurethanes were much more elastic than the commercially available ones and thus more able to withstand opening and closing of cracks due to temperature changes. The water ingress in specimens with healed cracks was found to decrease with increasing viscosity of the polyurethanes. At a temperature of 50 degrees C, the polyurethanes were able to heal cracks so that the water absorption of cracked mortar was reduced to a value that was comparable to the water absorption of uncracked mortar. Also, a strength regain of 100% or more was obtained. Therefore, using self-healing concrete in building facades may have a positive effect on the durability and service life of the construction elements. (c) 2018 American Society of Civil Engineers

Generation of maximum spin entanglement induced by cavity field in quantum-dot systems

Equivalent-neighbor interactions of the conduction-band electron spins of quantum dots in the model of Imamoglu et al. [Phys. Rev. Lett. 83, 4204 (1999)] are analyzed. Analytical solution and its Schmidt decomposition are found and applied to evaluate how much the initially excited dots can be entangled to the remaining dots if all of them are initially disentangled. It is demonstrated that the perfect maximally entangled states (MES) can only be generated in the systems of up to 6 dots with a single dot initially excited. It is also shown that highly entangled states, approximating the MES with a good accuracy, can still be generated in systems of odd number of dots with almost half of them being excited. A sudden decrease of entanglement is observed by increasing the total number of dots in a system with a fixed number of excitations.Comment: 6 pages, 7 figures, to appear in Phys. Rev.

Dimension in a Radiative Stellar Atmosphere

Dimensional scales are examined in an extended 3+1 Vaidya atmosphere surrounding a Schwarzschild source. At one scale, the Vaidya null fluid vanishes and the spacetime contains only a single spherical 2-surface. Both of these behaviors can be addressed by including higher dimensions in the spacetime metric.Comment: to appear in Gen. Rel. Gra

Investigating distribution of practice effects for the learning of foreign language verb morphology in the young learner classroom

Within limited-input language classrooms, understanding the effect of distribution of practice (spacing between practice) on learning is critical, yet evidence is conflicting and of limited relevance for young learners. For second language (L2) grammar learning, some studies reveal advantages for spacing of 7 days or more (Bird, 2010; Rogers, 2015), but others for shorter spacing (Suzuki, 2017). Further, little is known about the role of cognitive individual differences (e.g., language analytic ability) in mediating practice distribution effects for L2 grammatical knowledge development and retention (Suzuki & DeKeyser, 2017). To address this gap, this classroom-based study investigated whether distribution of practice and language analytic ability moderated the effectiveness of explicit, input-based grammar instruction for young first language (L1) English learners of French (aged 8 to 11). The study revealed minimal differences between longer (7-day) versus shorter (3.5-day) spacing of practice for learning an L2 French verb inflection subsystem, at either post- or delayed post-test. Minimal group-level gains and substantial within-group variation in performance at post-tests was observed. Accuracy of practice during training and language analytic ability were significantly associated with post-test performance under both practice schedules. These findings indicated that within an ecologically valid classroom context, differences in distribution of practice had limited impact on learner performance on our tests; rather, individual learner differences were more critical in moderating learning. This highlights the importance of considering individual learner differences in the development of resources and the potential of digital tools for dynamically adapting instruction to suit individuals

Periodontal screening and referral behaviour of general dental practitioners in Flanders.

peer reviewedOBJECTIVES: The objective of this study was to investigate the screening and referral behaviour of Flemish dentists concerning periodontitis and more specific, the use of the Dutch Periodontal Screening Index (DPSI). MATERIALS AND METHODS: An online questionnaire was electronically distributed through the different professional dental societies. It consisted of two parts: the first aimed at describing the profile of the dentist. The second part inquired the screening method, when this was applied, periodontal risk factors and referral behaviour. RESULTS: One thousand fifty dentists attended to the questionnaire. One hundred fifty-nine questionnaires were excluded since they did not match the target audience. Sixty-four percent of Flemish dentists used DPSI as a periodontal screening method, 28% screened based on probing pocket depth, 4% used solely radiographs and 4% had no screening method at all. The usage of DPSI is influenced by the year of graduation: the longer the dentists were graduated, the less they used DPSI. No influence of sex, education centre and location was found. Referral behaviour is influenced by different patient- and dentist-related factors. CONCLUSIONS: Regarding the screening behaviour, there seems a consensus among Flemish dentists that a periodontal probe should be used. For referral, there is no consensus about if and when to refer to a specialist. CLINICAL RELEVANCE: It is encouraging that 92% of the Flemish general dental practitioners use a probe when screening for periodontitis. However, DPSI is mainly used by younger dentists. An effort should be made to encourage all dentists to use this, so that in every patient, periodontitis can be detected timely, securing the best treatment outcome

Morphosyntactic processing in late second-language learners

The goal of the present study was to investigate the electro- physiological correlates of second-language (L2) morphosyn- tactic processing in highly proficient late learners of an L2 with long exposure to the L2 environment. ERPs were col- lected from 22 English–Spanish late learners while they read sentences in which morphosyntactic features of the L2 present or not present in the first language (number and gender agree- ment, respectively) were manipulated at two different sentence positions—within and across phrases. The results for a control group of age-matched native-speaker Spanish participants in- cluded an ERP pattern of LAN-type early negativity followed by P600 effect in response to both agreement violations and for both sentence positions. The late L2 learner results included a similar pattern, consisting of early negativity followed by P600, in the first sentence position (within-phrase agreement viola- tions) but only P600 effects in the second sentence position (across-phrase agreement violation), as well as significant am- plitude and onset latency differences between the gender and the number violation effects in both sentence positions. These results reveal that highly proficient learners can show electro- physiological correlates during L2 processing that are qualita- tively similar to those of native speakers, but the results also indicate the contribution of factors such as age of acquisition and transfer processes from first language to L

A database of whole-body action videos for the study of action, emotion, and untrustworthiness

We present a database of high-definition (HD) videos for the study of traits inferred from whole-body actions. Twenty-nine actors (19 female) were filmed performing different actions—walking, picking up a box, putting down a box, jumping, sitting down, and standing and acting—while conveying different traits, including four emotions (anger, fear, happiness, sadness), untrustworthiness, and neutral, where no specific trait was conveyed. For the actions conveying the four emotions and untrustworthiness, the actions were filmed multiple times, with the actor conveying the traits with different levels of intensity. In total, we made 2,783 action videos (in both two-dimensional and three-dimensional format), each lasting 7 s with a frame rate of 50 fps. All videos were filmed in a green-screen studio in order to isolate the action information from all contextual detail and to provide a flexible stimulus set for future use. In order to validate the traits conveyed by each action, we asked participants to rate each of the actions corresponding to the trait that the actor portrayed in the two-dimensional videos. To provide a useful database of stimuli of multiple actions conveying multiple traits, each video name contains information on the gender of the actor, the action executed, the trait conveyed, and the rating of its perceived intensity. All videos can be downloaded free at the following address: http://www-users.york.ac.uk/~neb506/databases.html. We discuss potential uses for the database in the analysis of the perception of whole-body actions