Distance measurement using the change in junction voltage across a laser diode due to the self-mixing effect

Conventional detection scheme for self-mixing sensors uses an integrated photodiode within the laser package to monitor the self mixing signal. This arrangement can be simplified by directly obtaining the self-mixing signals across the laser diode itself and omitting the photodiode. This work reports on a Vertical-Cavity Surface-Emitting Laser (VCSEL) based selfmixing sensor using the laser junction voltage to obtain the selfmixing signal. We show that the same information can be obtained with only minor changes to the extraction circuitry leading to potential cost saving with reductions in component costs and complexity and significant increase in bandwidth favoring high speed modulation. Experiments using both photo current and voltage detection were carried out and the results obtained show good agreement with the theory.

Performance analysis of multi-radio AODV in hybrid wireless mesh networks

Wireless Mesh Networks (WMNs), based on commodity hardware, present a promising technology for a wide range of applications due to their self-configuring and self-healing capabilities, as well as their low equipment and deployment costs. One of the key challenges that WMN technology faces is the limited capacity and scalability due to co-channel interference, which is typical for multi-hop wireless networks. A simple and relatively low-cost approach to address this problem is the use of multiple wireless network interfaces (radios) per node. Operating the radios on distinct orthogonal channels permits effective use of the frequency spectrum, thereby, reducing interference and contention. In this paper, we evaluate the performance of the multi-radio Ad-hoc On-demand Distance Vector (AODV) routing protocol with a specific focus on hybrid WMNs. Our simulation results show that under high mobility and traffic load conditions, multi-radio AODV offers superior performance as compared to its single-radio counterpart. We believe that multi-radio AODV is a promising candidate for WMNs, which need to service a large number of mobile clients with low latency and high bandwidth requirements.

Sharing Narratives Online: An international, self-organising curriculum in rural health

The aim of the Rural Medicine Rotation (RMR) at the University of Queensland (UQ) is to give all third year medical students exposure to and an understanding of, clinical practice in Australian rural or remote locations. A difficulty in achieving this is the relatively short period of student clinical placements, in only one or two rural or remote locations. A web-based Clinical Discussion Board (CDB) has been introduced to address this problem by allowing students at various rural sites to discuss their rural experiences and clinical issues with each other. The rationale is to encourage an understanding of the breadth and depth of rural medicine through peer-based learning. Students are required to submit a minimum of four contributions over the course of their six week rural placement. Analysis of student usage patterns shows that the majority of students exceeded the minimum submission criteria indicating motivation rather than compulsion to contribute to the CDB. There is clear evidence that contributing or responding to the CDB develops studentâ??s critical thinking skills by giving and receiving assistance from peers, challenging attitudes and beliefs and stimulating reflective thought. This is particularly evident in regard to issues involving ethics or clinical uncertainty, subject areas that are not in the medical undergraduate curriculum, yet are integral to real-world medical practice. The CDB has proved to be a successful way to understand the concerns and interests of third year medical students immersed in their RMR and also in demonstrating how technology can help address the challenge of supporting students across large geographical areas. We have recently broadened this approach by including students from the Rural Program at The Ohio State University College of Medicine. This important international exchange of ideas and approaches to learning is expected to broaden clinical training content and improve understanding of rural issues.