Assessing the Impact of Automatic vs. Controlled Rotations on Spatial Transfer with a Joystick and a Walking Interface in VR

Part 1: Long and Short PapersInternational audienceWe present a user study assessing spatial transfer in a 3D navigation task, with two different motor activities: a minimal (joystick) and an extensive motor activity (walking Interface), with rotations of the viewpoint either controlled by the user, or automatically managed by the system. The task consisted in learning a virtual path of a 3D model of a real city, with either one of these four conditions: Joystick / Treadmill Vs Manual Rotation / Automatic Rotation. We assessed spatial knowledge with six spatial restitution tasks. To assess the interfaces used, we analyzed also the interaction data acquired during the learning path. Our results show that the direct control of rotations has different effects, depending on the motor activity required by the input modality. The quality of spatial representation increases with the Treadmill when rotations are enabled. With the Joystick, controlling the rotations affect spatial representations. We discuss our findings in terms of cognitive, sensorimotor processes and human computer interaction issues

Do Nurses Use Discourse Markers Differently when Using Their Second Language as Opposed to Their First while Interviewing Patients?

This study examined whether discourse-marker use changes in nurse-patient interactions as a function of nurses using their first (L1) or second (L2) language. Discourse markers were analyzed as turn-maintenance markers that indicate acknowledgement and discourse-shift markers that signal shifts of a topic or speaker in the conversation. These two categories differ in terms of degree of discourse management and interactional control. Sixteen nurses conducted a pain-assessment interview with a patient native speaker of English and with a patient native speaker of French, where the nurses used their own L1 in one case and their own weaker L2 in the other. The first hypothesis, that nurses would generally use discourse markers more frequently in the L1 than in the L2, was not supported. The second hypothesis, that nurses would use discourse-shift markers less frequently in their L2 compared to the L1, relative to their (baseline) use of turn-maintenance markers, was supported. The findings, especially the support for the second hypothesis, could have implications for the development of L2 training for health practitioners.</p

UNC-4 antagonizes Wnt signaling to regulate synaptic choice in the C. elegans motor circuit

Coordinated movement depends on the creation of synapses between specific neurons in the motor circuit. In C. elegans, this important decision is regulated by the UNC-4 homeodomain protein. unc-4 mutants are unable to execute backward locomotion because VA motor neurons are mis-wired with inputs normally reserved for their VB sisters. We have proposed that UNC-4 functions in VAs to block expression of VB genes. This model is substantiated by the finding that ectopic expression of the VB gene ceh-12 (encoding a homolog of the homeodomain protein HB9) in unc-4 mutants results in the mis-wiring of posterior VA motor neurons with VB-like connections. Here, we show that VA expression of CEH-12 depends on a nearby source of the Wnt protein EGL-20. Our results indicate that UNC-4 prevents VAs from responding to a local EGL-20 cue by disabling a canonical Wnt signaling cascade involving the Frizzled receptors MIG-1 and MOM-5. CEH-12 expression in VA motor neurons is also opposed by a separate pathway that includes the Wnt ligand LIN-44. This work has revealed a transcriptional mechanism for modulating the sensitivity of specific neurons to diffusible Wnt ligands and thereby defines distinct patterns of synaptic connectivity. The existence of comparable Wnt gradients in the vertebrate spinal cord could reflect similar roles for Wnt signaling in vertebrate motor circuit assembly

Novel instrument for high-pressure research at ultra-high temperatures

A resistively heated diamond-anvil cell has been used to achieve pressures of 110 kbar at temperatures exceeding 1200/sup 0/C for periods long enough to collect x-ray powder diffraction data with energy-dispersive techniques using ''white'' x-radiation produced at the Stanford Synchrotron Radiation Laboratory. 9 refs., 1 fig