Dynamic FOV visible light communications receiver for dense optical networks

This study explores how the field-of-view (FOV) of a visible light communications (VLCs) receiver can be manipulated to realise the best signal-to-noise ratio (SNR) while supporting device mobility and optimal access point (AP) selection. The authors propose a dynamic FOV receiver that changes its aperture according to receiver velocity, location, and device orientation. The D-FOV technique is evaluated through modelling, analysis, and experimentation in an indoor environment comprised of 15 VLC APs. The proposed approach is also realised as an algorithm that is studied through analysis and simulation. The results of the study indicate the efficacy of the approach including a 3X increase in predicted SNR over static FOV approaches based on measured received signal strength in the testbed. Additionally, the collected data reveal that D-FOV increases effectiveness in the presence of noise. Finally, the study describes the tradeoffs among the number of VLC sources, FOV, user device velocity, and SNR as a performance metric.Accepted manuscrip

Further detections of OH masers in carbon stars with silicate features

A sample of J-type carbon stars was searched for OH maser emission. The new detection of three OH lines towards two silicate carbon stars is reported. In V778 Cyg, previously known as the main-lines (1665 and 1667 MHz) maser source, the satellite 1612 MHz emission was discovered while in NSV 2814 the main OH lines were detected. The presence of OH maser lines confirms the former suggestion that oxygen-rich material is located in the vicinity ($\approx$ $10^{15-16}$ cm) of silicate carbon stars.Comment: LaTeX2e, 4 pages with 2 figure

Marginalizing experience: A critical analysis of public discourse surrounding stem cell research in Australia (2005-6).

Over the past decade, stem cell science has generated considerable public and political debate. These debates tend to focus on issues concerning the protection of nascent human life and the need to generate medical and therapeutic treatments for the sick and vulnerable. The framing of the public debate around these issues not only dichotomises and oversimplifies the issues at stake, but tends to marginalise certain types of voices, such as the women who donate their eggs and/or embryos to stem cell research and the patients who might benefit from its potential clinical outcomes. This paper draws on empirical research conducted on a recent stem cell policy episode in Australia. From the qualitative examination of 109 newspaper opinion editorials and twenty-three in-depth interviews, it is argued that these voices are marginalised because they are based on discourses that have less epistemological status in public debate. Our results suggest that the personal experiences of women and patients are marginalised by the alliances that form between more powerful discourse communities that use science as a source of authority and legitimation. It is argued that members of these communities establish legitimacy and assert authority in public debate by discursively deploying science in claims that marginalise other epistemologies. Implications are discussed along with suggestions for a more enriched and inclusive public debate. Keywords Stem cellsCloningBioethicsPublic polic

Continuous volumetric imaging via an optical phase-locked ultrasound lens

In vivo imaging at high spatiotemporal resolution is key to the understanding of complex biological systems. We integrated an optical phase-locked ultrasound lens into a two-photon fluorescence microscope and achieved microsecond-scale axial scanning, thus enabling volumetric imaging at tens of hertz. We applied this system to multicolor volumetric imaging of processes sensitive to motion artifacts, including calcium dynamics in behaving mouse brain and transient morphology changes and trafficking of immune cells

High performance photonic microwave filters based on a 50GHz optical soliton crystal Kerr micro-comb

We demonstrate a photonic radio frequency (RF) transversal filter based on an integrated optical micro-comb source featuring a record low free spectral range of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high number of taps, or wavelengths for the transversal filter results in significantly increased performance including a QRF factor more than four times higher than previous results. Further, by employing both positive and negative taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using Gaussian apodization, together with a tunable centre frequency covering the RF spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically adjustable filter shapes. Our experimental results match well with theory, showing that our transversal filter is a competitive solution to implement advanced adaptive RF filters with broad operational bandwidths, high frequency selectivity, high reconfigurability, and potentially reduced cost and footprint. This approach is promising for applications in modern radar and communications systems.Comment: 19 pages, 12 figures, 107 reference

Selective decrease in consultations and antibiotic prescribing for acute respiratory tract infections in UK primary care up to 2006

BACKGROUND: The aim of this study was to estimate trends in primary care consultations and antibiotic prescribing for acute respiratory tract infections (RTIs) in the UK from 1997 to 2006.METHODS: Data were analysed for 100,000 subjects registered with 78 family practices in the UK General Practice Research Database; the numbers of consultations for RTI and associated antibiotic prescriptions were enumerated.RESULTS: The consultation rate for RTI declined in females from 442.2 per 1000 registered patients in 1997 to 330.9 in 2006, and in males from 318.5 to 249.0. The rate of consultations for colds, rhinitis and upper respiratory tract infection (URTI) declined by 4.2 (95% CI 2.3-6.1) per 1000 per year in females and by 3.6 (2.3-4.8) in males. The rate of antibiotic prescribing for RTI was higher in females and declined by 8.5 (2.0-15.1) per 1000 in females and 6.7 (2.7-10.8) in males. For colds, rhinitis and URTI, the proportion of consultations with antibiotics was prescribed declined by 1.7% per year in females and 1.8% in males.CONCLUSIONS: Decreasing frequency of consultation and antibiotic prescription for colds, rhinitis and 'URTI' continues to drive a reduction in the rate of antibiotic utilization for RTIs