208 research outputs found
Sensor node localisation using a stereo camera rig
In this paper, we use stereo vision processing techniques to
detect and localise sensors used for monitoring simulated
environmental events within an experimental sensor network testbed. Our sensor nodes communicate to the camera through patterns emitted by light emitting diodes (LEDs). Ultimately, we envisage the use of very low-cost, low-power,
compact microcontroller-based sensing nodes that employ
LED communication rather than power hungry RF to transmit data that is gathered via existing CCTV infrastructure.
To facilitate our research, we have constructed a controlled
environment where nodes and cameras can be deployed and
potentially hazardous chemical or physical plumes can be
introduced to simulate environmental pollution events in a
controlled manner. In this paper we show how 3D spatial
localisation of sensors becomes a straightforward task when
a stereo camera rig is used rather than a more usual 2D
CCTV camera
Influence of the charge carrier tunneling processes on the recombination dynamics in single lateral quantum dot molecules
We report on the charge carrier dynamics in single lateral quantum dot
molecules and the effect of an applied electric field on the molecular states.
Controllable electron tunneling manifests itself in a deviation from the
typical excitonic decay behavior which is strongly influenced by the tuning
electric field and inter-molecular Coulomb energies. A rate equation model is
developed to gain more insight into the charge transfer and tunneling
mechanisms. Non-resonant (phonon-mediated) electron tunneling which changes the
molecular exciton character from direct to indirect, and vice versa, is found
to be the dominant tunable decay mechanism of excitons besides radiative
recombination.Comment: 4 pages, 4 figure
Polarization fine-structure and enhanced single-photon emission of self-assembled lateral InGaAs quantum dot molecules embedded in a planar micro-cavity
Single lateral InGaAs quantum dot molecules have been embedded in a planar
micro-cavity in order to increase the luminescence extraction efficiency. Using
a combination of metal-organic vapor phase and molecular beam epitaxy samples
could be produced that exhibit a 30 times enhanced single-photon emission rate.
We also show that the single-photon emission is fully switchable between two
different molecular excitonic recombination energies by applying a lateral
electric field. Furthermore, the presence of a polarization fine-structure
splitting of the molecular neutral excitonic states is reported which leads to
two polarization-split classically correlated biexciton exciton cascades. The
fine-structure splitting is found to be on the order of 10 micro-eV.Comment: 14 pages, 4 figures; the following article has been submitted to
Journal of Applied Physics (29th ICPS - invited paper); after it is
published, it will be found at http://jap.aip.org
Remote real-time monitoring of subsurface landfill gas migration
The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months. Copyright 2011 by the authors; licensee MDPI, Basel, Switzerland
Guided self-assembly of lateral InAs/GaAs quantum-dot molecules for single molecule spectroscopy
We report on the growth and characterization of lateral InAs/GaAs (001) quantum-dot molecules (QDMs) suitable for single QDM optical spectroscopy. The QDMs, forming by depositing InAs on GaAs surfaces with self-assembled nanoholes, are aligned along the [] direction. The relative number of isolated single quantum dots (QDs) is substantially reduced by performing the growth on GaAs surfaces containing stepped mounds. Surface morphology and X-ray measurements suggest that the strain produced by InGaAs-filled nanoholes superimposed to the strain relaxation at the step edges are responsible for the improved QDM properties. QDMs are Ga-richer compared to single QDs, consistent with strain- enhanced intermixing. The high optical quality of single QDMs is probed by micro-photoluminescence spectroscopy in samples with QDM densities lower than 108 cmâ2
Effect of Bio-OssÂź Collagen and Collagen Matrix on Bone Formation
Objective: to compare the amount of new bone produced by Bio-Oss Ÿ Collagen to that produced by collagen matrix in vivo. Method: eighteen bone defects, 5mm by 10mm were created in the parietal bone of 9 New Zealand White rabbits. 6 defects were grafted with Bio-Oss Ÿ Collagen. 6 defects were grafted with collagen matrix alone (positive control) and 6 were left empty (negative control). Animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Quantitative analysis of new bone formation was made on 100 sections (50 sections for each group) using image analysis. Results: A total of 339% more new bone was present in defects grafted with Bio-Oss Ÿ Collagen than those grafted with collagen matrix (positive control). No bone was formed in the negative control group. Conclusion: Bio-Oss Ÿ Collagen has the effect of stimulating new bone formation locally compared with collagen matrix in vivo. Bio-Oss Ÿ Collagen may be utilized as a bone graft material. © Wong and Rabie; Licensee Bentham Open.published_or_final_versio
Non-invasive management of peripheral arterial disease.
BACKGROUND: Peripheral arterial disease (PAD) is common and symptoms can be debilitating and lethal. Risk management, exercise, radiological and surgical intervention are all valuable therapies, but morbidity and mortality rates from this disease are increasing. Circulatory enhancement can be achieved using simple medical electronic devices, with claims of minimal adverse side effects. The evidence for these is variable, prompting a review of the available literature. METHODS: Embase and Medline were interrogated for full text articles in humans and written in English. Any external medical devices used in the management of peripheral arterial disease were included if they had objective outcome data. RESULTS: Thirty-one papers met inclusion criteria, but protocols were heterogenous. The medical devices reported were intermittent pneumatic compression (IPC), electronic nerve (NMES) or muscle stimulators (EMS), and galvanic electrical dressings. In patients with intermittent claudication, IPC devices increase popliteal artery velocity (49-70Â %) and flow (49-84Â %). Gastrocnemius EMS increased superficial femoral artery flow by 140Â %. Over 4.5-6 months IPC increased intermittent claudication distance (ICD) (97-150Â %) and absolute walking distance (AWD) (84-112Â %), with an associated increase in quality of life. NMES of the calf increased ICD and AWD by 82Â % and 61-150Â % at 4 weeks, and 26Â % and 34Â % at 8 weeks. In patients with critical limb ischaemia IPC reduced rest pain in 40-100Â % and was associated with ulcer healing rates of 26Â %. IPC had an early limb salvage rate of 58-83Â % at 1-3 months, and 58-94Â % at 1.5-3.5Â years. No studies have reported the use of EMS or NMES in the management of CLI. CONCLUSION: There is evidence to support the use of IPC in the management of claudication and CLI. There is a building body of literature to support the use of electrical stimulators in PAD, but this is low level to date. Devices may be of special benefit to those with limited exercise capacity, and in non-reconstructable critical limb ischaemia. Galvanic stimulation is not recommended
Research data management as a âwicked problemâ
Purpose â The purpose of this paper is to explore the usefulness of the concept to thinking about Research Data Management (RDM). The concept of âwicked problemsâ seeks to differentiate very complex, intractable challenges from tamer issues where approaches to problem solving are well-understood. Design/methodology/approach â The paper is based on and co-authored by a collaboration of practitioners from libraries, information technology and research administration, with facilitators from the Sheffield Information School. Participants worked together in two-day-long workshops to understand the wicked problem concept and advice on leadership in wicked problem contexts. Findings â Participants concurred that RDM had many features of a wicked problem and most of Grintâs advice on leadership for wicked problems also resonated. Some elements of the issue were simple; participants were optimistic about improving the situation over time. Participants were resistant to the more negative or fatalistic connotations of the phrase âwicked problemâ. Viewing RDM as a wicked problem is an interesting way of looking at it as a challenge for support professionals. Practical implications â The notion of a wicked problem is a generative concept that can be usefully added to professional vocabulary. Originality/value â The paper captures an in-depth response from practitioners to the notion of wicked problems as a lens for examining RDM
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