An off-board quantum point contact as a sensitive detector of cantilever motion

Recent advances in the fabrication of microelectromechanical systems (MEMS) and their evolution into nanoelectromechanical systems (NEMS) have allowed researchers to measure extremely small forces, masses, and displacements. In particular, researchers have developed position transducers with resolution approaching the uncertainty limit set by quantum mechanics. The achievement of such resolution has implications not only for the detection of quantum behavior in mechanical systems, but also for a variety of other precision experiments including the bounding of deviations from Newtonian gravity at short distances and the measurement of single spins. Here we demonstrate the use of a quantum point contact (QPC) as a sensitive displacement detector capable of sensing the low-temperature thermal motion of a nearby micromechanical cantilever. Advantages of this approach include versatility due to its off-board design, compatibility with nanoscale oscillators, and, with further development, the potential to achieve quantum limited displacement detection.Comment: 5 pages, 5 figure

Towards Lean and Elegant Self-Motion Simulation in Virtual Reality

Despite recent technological advances, convincing self-motion simulation in Virtual Reality (VR) is difficult to achieve, and users often suffer from motion sickness and/or disorientation in the simulated world. Instead of trying to simulate self-motions with physical realism (as is often done for, e.g., driving or flight simulators), we propose in this paper a perceptually oriented approach towards selfmotion simulation. Following this paradigm, we performed a series of psychophysical experiments to determine essential visual, auditory, and vestibular/tactile parameters for an effective and perceptually convincing self-motion simulation. These studies are a first step towards our overall goal of achieving lean and elegant selfmotion simulation in Virtual Reality (VR) without physically moving the observer. In a series of psychophysical experiments about the self-motion illusion (circular vection), we found that (i) vection as well as presence in the simulated environment is increased by a consistent, naturalistic visual scene when compared to a sliced, inconsistent version of the identical scene, (ii) barely noticeable marks on the projection screen can increase vection as well as presence in an unobtrusive manner, (iii) physical vibrations of the observer’s seat can enhance the vection illusion, and (iv) spatialized 3D audio cues embedded in the simulated environment increase the sensation of self-motion and presence. We conclude that providing consistent cues about self-motion to multiple sensory modalities can enhance vection, even if physical motion cues are absent. These results yield important implications for the design of lean and elegant self-motion simulators

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The proteasome system in health and disease.

The proteasome is involved in the regulation of all cellular pathways and consequently plays a central role in the control of cellular homeostasis. Together with its regulators, it is at the frontline, both as an actor and as a target, in human health and when homeostasis is disturbed in disease. In this review, we aim to provide an overview of the many levels at which the functions of the proteasome and its regulators can be regulated to cope with cellular needs or are altered in pathological conditions