Multimodal metaphors for generic interaction tasks in virtual environments

Virtual Reality (VR) Systeme bieten zusätzliche Ein- und Ausgabekanäle für die Interaktion zwischen Mensch und Computer in virtuellen Umgebungen. Solche VR Technologien ermöglichen den Anwendern bessere Einblicke in hochkomplexe Datenmengen, stellen allerdings auch hohe Anforderungen an den Benutzer bezüglich der Fähigkeiten mit virtuellen Objekten zu interagieren. In dieser Arbeit werden sowohl die Entwicklung und Evaluierung neuer multimodaler Interaktionsmetaphern für generische Interaktionsaufgaben in virtuellen Umgebungen vorgestellt und diskutiert. Anhand eines VR Systems wird der Einsatz dieser Konzepte an zwei Fallbeispielen aus den Domänen der 3D-Stadtvisualisierung und seismischen Volumendarstellung aufgezeigt

Conception et évaluation d'une technique d'interaction pour la sélection d'un volume dans un nuage de point 3D

International audienceA fundamental task needed when using a 3D virtual environment is the ability to select. This is necessary to perform local treatments, such as translating an object. While classical techniques, such as ray-casting, works well for large objects it becomes more difficult when the need for precision is greater and almost impossible for a point selection. To select a set of points in a point cloud we created a novel selection technique. It allows to select complex shapes while remaining simple to use. Using our technique relies on three principles: 1) selecting points consists in progressively elaborating a cylinder-like shape (the worm) through the sequential definition of several sections ; 2) a section is defined between two contours linked together with straight lines; 3) each contour is a freely drawn closed line. A user study reveals that our technique is significantly faster than a classical selection mechanism based on predefined volumes such as spheres or cuboids while maintaining a comparable level of precision and recall .Une tâche fondamentale d'interaction dans un environne-ment 3D est la possibilité de réaliser une sélection. Elle est nécessaire pour appliquer des traitements locaux, comme le déplacement d'un objet. Bien que pour les objets larges les techniques classiques fonctionnent bien, comme le lancer de rayon, elles deviennent moins adaptées quand le besoin en précision augmente. Elles sont même impossibles à utiliser pour sélectionner des ensembles de points. Pour ces ensembles de points, nous proposons une nouvelle technique de sélection. Elle permet de sélectionner des formes complexes tout en restant simple d'utilisation. Elle repose sur trois principes : 1) la sélection de points consiste à progressivement élaborer une forme rappelant vaguement un cylindre à travers la définition itérative de sections ; 2) une section est définie par deux contours liés ensemble par des lignes droites ; 3) chaque contour est un tracé fermé dessiné librement. Les résultats d'une évaluation utilisateur établissent que notre technique est significativement plus rapide que les techniques plus classiques basées sur des volumes prédéfinis, comme des sphères ou des cuboïdes, tout en gardant un niveau de précision et de rappel comparable

Cardiac Troponin and Recurrent Major Vascular Events after Minor Stroke or Transient Ischemic Attack

Objective: This study was undertaken to investigate whether high-sensitivity cardiac troponin T (hs-cTnT) is associated with major adverse cardiovascular events (MACE) in patients with minor stroke or transient ischemic attack (TIA), and whether this association differs after risk stratification based on the Age, Blood Pressure, Clinical Features, Duration of Symptoms, Diabetes (ABCD2 ) score. Methods: INSPiRE-TMS was a randomized controlled trial allocating patients with minor stroke or TIA to an intensified support program or conventional care. In this post hoc analysis, participants were categorized using hs-cTnT levels (5th generation; Roche Diagnostics, Manheim, Germany; 99th percentile upper reference limit [URL] = 14ng/l). Vascular risk was stratified using the ABCD2 score (lower risk = 0-5 vs higher risk = 6-7). Cox proportional hazard regression was performed using covariate adjustment and propensity score matching (PSM) for the association between hs-cTnT and MACE (stroke/nonfatal coronary event/vascular death). Results: Among 889 patients (mean age = 70 years, 37% female), MACE occurred in 153 patients (17.2%) during a mean follow-up of 3.2 years. hs-cTnT was associated with MACE (9.3%/yr, >URL vs 4.4%/yr, ≤URL, adjusted hazard ratio [HR] = 1.63 [95% confidence interval (CI) = 1.13-2.35], adjusted HR [Q4 vs Q1 ] = 2.57 [95% CI = 1.35-4.97], adjusted HR [log-transformed] = 2.31 [95% CI = 1.37-3.89]). This association remained after PSM (adjusted HR = 1.76 [95% CI = 1.14-2.72]). There was a significant interaction between hs-cTnT and ABCD2 category for MACE occurrence (pinteraction = 0.04). In the lower risk category, MACE rate was 9.5%/yr in patients with hs-cTnT > URL, which was higher than in those ≤URL (3.8%/yr) and similar to the overall rate in the higher risk category. Interpretation: hs-cTnT levels are associated with incident MACE within 3 years after minor stroke or TIA and may help to identify high-risk individuals otherwise deemed at lower risk based on the ABCD2 score. If confirmed in independent validation studies, this might warrant intensified secondary prevention measures and cardiac diagnostics in stroke patients with elevated hs-cTnT

Phylogenetic placement of environmental sequences using taxonomically reliable databases helps to rigorously assess dinophyte biodiversity in Bavarian lakes (Germany).

1. Reliable determination of organisms is a prerequisite to explore their spatial and temporal occurrence and to study their evolution, ecology, and dispersal. In Europe, Bavaria (Germany) provides an excellent study system for research on the origin and diversification of freshwater organisms including dinophytes, due to the presence of extensive lake districts and ice age river valleys. Bavarian freshwater environments are ecologically diverse and range from deep nutrient‐poor mountain lakes to shallow nutrient‐rich lakes and ponds. 2. We obtained amplicon sequence data (V4 region of small subunit‐rRNA, c. 410 bp long) from environmental samples collected at 11 sites in Upper Bavaria. We found 186 operational taxonomic units (OTUs) associated with Dinophyceae that were further classified by means of a phylogenetic placement approach. 3. The maximum likelihood tree inferred from a well‐curated reference alignment comprised a systematically representative set of 251 dinophytes, covering the currently known molecular diversity and OTUs linked to type material if possible. Environmental OTUs were scattered across the reference tree, but accumulated mostly in freshwater lineages, with 79% of OTUs placed in either Apocalathium, Ceratium, or Peridinium, the most frequently encountered taxa in Bavaria based on morphology. 4. Twenty‐one Bavarian OTUs showed identical sequences to already known and vouchered accessions, two of which are linked to type material, namely Palatinus apiculatus and Theleodinium calcisporum. Particularly within Peridiniaceae, delimitation of Peridinium species was based on the intraspecific sequence variation. 5. Our approach indicates that high‐throughput sequencing of environmental samples is effective for reliable determination of dinophyte species in Bavarian lakes. We further discuss the importance of well‐curated reference databases that remain to be developed in the future

Moving Towards Consistent Depth Perception In Stereoscopic Projection-Based Augmented Reality

Stereoscopic projection-based augmented reality (AR) is a promising technology for creating an effective illusion of virtual and real objects coexisting within the same space. By using projection technology, two-dimensional (2D) textures as well as three-dimensional (3D) virtual objects can be displayed on arbitrary physical objects. However, depending on the geometry of the projection surface, even a single virtual object could be projected with varying depths, orientations, and forms. For these reasons, it is an open question whether or not a geometrically-correct projection leads to a consistent depth perception of the AR environment. We performed an experiment to analyze how humans perceive depths of objects that are stereoscopically projected at different surfaces in a projection-based AR environment. In a perceptual matching task the participants had to adjust the depth of one of two visual stimuli, which were displayed at different depths with varying parallaxes, until they estimated the depths of both stimuli to match. The results indicate that the effect of parallax on the estimation of matching depths significantly depends on the participant\u27s experience with stereoscopic display. Regular users were able to match the depths of both stimuli with a mean absolute error of less than one centimeter, whereas less experienced users made errors in the range of more than 2cm on average. We performed a confirmatory study to verify our findings with more ecologically valid projection-based AR stimuli