High-speed tunable microwave photonic notch filter based on phase modulator incorporated Lyot filter.

A high-speed tunable microwave photonic notch filter with ultrahigh rejection ratio is presented, which is achieved by semiconductor optical amplifier (SOA)-based single-sideband modulation and optical spectral filtering with a phase modulator-incorporated Lyot (PM-Lyot) filter. By varying the birefringence of the phase modulator through electro-optic effect, electrically tuning of the microwave photonic notch filter is experimentally achieved at tens of gigahertz speed. The use of SOA-polarizer based single-sideband modulation scheme provides good sideband suppression over a wide frequency range, resulting in an ultrahigh rejection ratio of the microwave photonic notch filter. Stable filter spectrum with bandstop rejection ratio over 60 dB is observed over a frequency tuning range from 1.8 to 10 GHz. Compare with standard interferometric notch filter, narrower bandwidth and sharper notch profile are achieved with the unique PM-Lyot filter, resulting in better filter selectivity. Moreover, bandwidth tuning is also achieved through polarization adjustment inside the PM-Lyot filter, that the 10-dB filter bandwidth is tuned from 0.81 to 1.85 GHz.

A cost effectiveness analysis of community water fluoridation in New Zealand.

AIM: The aim of the study was to use recent data to determine whether Community Water Fluoridation (CWF) remains a cost effective public health intervention in New Zealand, given a reduction in dental caries in all communities over time. METHOD: Local authorities that fluoridated their water supplies were asked to complete a questionnaire regarding fixed and variable costs incurred from CWF. Cost savings were calculated using data from the 2009 New Zealand Oral Health Survey. The cost effectiveness of CWF in conjunction with treatment per dmft/DMFT averted was compared to an alternative of treatment alone. Calculations were made for communities with populations of less than 5,000, 5,000 to 10,000, 10,001 to 50,000 and greater than 50,000. RESULTS: CWF was cost effective in all communities at base case. CWF remained cost effective for communities over 5,000 under all scenarios when sensitivity analysis was conducted. For communities under 5,000 the there was a positive net cost for CWF under certain scenarios. CONCLUSION: In this study, CWF was a cost effective public health intervention in New Zealand. For smaller communities cost effectiveness would be more dependent upon the population risk profile of the community.

Wideband co-site interference cancellation based on hybrid electrical and optical techniques.

A wideband co-site co-channel interference cancellation system (ICS), based on hybrid electrical and optical techniques, is proposed and is experimentally demonstrated. The demonstrated cancellation system subtracts the in-band wideband interfering signal from the received signal, such that the weak signal of interest (SOI) can be recovered. Our system utilizes a broadband radio frequency (RF) Balun transformer to invert the phase of the interfering signal, while electro-absorption modulated lasers are used for converting the RF signals into the optical domain to enable fine adjustment with the hybrid ICS. We experimentally achieve 45 dB of cancellation over a 220 MHz bandwidth, and over 57 dB of cancellation for a 10 MHz bandwidth, at a center frequency of 900 MHz. The proposed system also experimentally shows good cancellation (30 dB) over an enormously wide bandwidth of 5.5 GHz. To the best of our knowledge, this is the first demonstration of such a wide bandwidth cancellation with good cancellation depth. This property is extremely useful when there are multiple interference signals at various frequency bands. The proposed hybrid ICS has a spurious-free dynamic range of 93.2 dBm/Hz(2/3). Moreover, a 10 Gb/s SOI is recovered from a strong interfering signal, sweeping over 3 GHz bandwidth. A widely open eye diagram, as well as error-free bit-error rate measurements, is experimentally achieved, with the use of the hybrid ICS. The approach also works well for various frequency bands that are within the bandwidth of the Balun transformer and electro-absorption modulated lasers.

Insomnia - treatment pathways, costs and quality of life.

BACKGROUND: Insomnia is perhaps the most common sleep disorder in the general population, and is characterised by a range of complaints around difficulties in initiating and maintaining sleep, together with impaired waking function. There is little quantitative information on treatment pathways, costs and outcomes. The aims of this New Zealand study were to determine from which healthcare practitioners patients with insomnia sought treatment, treatment pathways followed, the net costs of treatment and the quality of life improvements obtained. METHODS: The study was retrospective and prevalence based, and was both cost effectiveness (CEA) and a cost utility (CUA) analysis. Micro costing techniques were used and a societal analytic perspective was adopted. A deterministic decision tree model was used to estimate base case values, and a stochastic version, with Monte Carlo simulation, was used to perform sensitivity analysis. A probability and cost were attached to each event which enabled the costs for the treatment pathways and average treatment cost to be calculated. The inputs to the model were prevalence, event probabilities, resource utilisations, and unit costs. Direct costs and QALYs gained were evaluated. RESULTS: The total net benefit of treating a person with insomnia was $482 (the total base case cost of $145 less health costs avoided of $628). When these results were applied to the total at-risk population in New Zealand additional treatment costs incurred were $6.6 million, costs avoided $28.4 million and net benefits were $21.8 million. The incremental net benefit when insomnia was "successfully" treated was $3,072 per QALY gained. CONCLUSIONS: The study has brought to light a number of problems relating to the treatment of insomnia in New Zealand. There is both inadequate access to publicly funded treatment and insufficient publicly available information from which a consumer is able to make an informed decision on the treatment and provider options. This study suggests that successful treatment of insomnia leads to direct cost savings and improved quality of life.

Societal costs of obstructive sleep apnoea syndrome.

AIM: To estimate the societal costs of obstructive sleep apnoea syndrome (OSAS) in New Zealand and develop a simulation tool to evaluate treatment options. METHOD: Treatment profiles, availability, uptake, and costs were based on services in the Wellington Region, and were used to develop a decision analytic model with micro costing of each potential outcome. Sensitivity analyses were conducted with 10,000 Monte Carlo simulations randomly varying each model parameter between high and low estimates. RESULTS: Total annual societal costs of OSAS for New Zealanders aged 30-60 years were estimated at $40 million (range $33-$90 million) or $419 per case, with accidents being the major contributor. This included 58% direct medical, 13% direct non-medical, 25% indirect, and 3% intangible costs. The estimated incremental net cost of treating OSAS was $389 per case treated (range $338-$427). The estimated incremental net direct medical cost per quality of life year (QALY) gained was $94 (range $56-$310). CONCLUSION: The estimated incremental direct medical cost per QALY gained by OSAS treatment is well below the average QALY cost ($6865) for drugs selected by PHARMAC to receive government subsidy for use in the healthcare system. Thus, the analysis strongly supports the cost effectiveness of OSAS treatment.

Economic cost of community-acquired pneumonia in New Zealand adults.

AIMS: The aim of this study was to evaluate the economic cost of community-acquired pneumonia (CAP) in New Zealand adults. Although this is an important illness, there is little published information on the national costs of treatment. Without such information, new treatment options cannot be evaluated in economic terms. METHODS: Costs were estimated from a societal perspective for the adult population (aged 15 years and over) using New Zealand age-specific hospital admission rates (average of 2000-2002), population data (2003), and unit costs (2003) in combination with international data on the proportion of pneumonia cases hospitalised. Univariate and multivariate sensitivity analyses were used to determine the major cost drivers and evaluate uncertainty in the estimates. RESULTS: It was estimated that in 2003 there were 26,826 episodes of pneumonia in adults; a rate of 859 per 100,000 people. The annual cost was estimated to be 63 million dollars, (direct medical costs of 29 million dollars; direct non-medical costs of 1 million dollars; lost productivity of 33 million dollars). CONCLUSIONS: The major generators of costs for community-acquired pneumonia are the number of hospitalisations (particularly for the group aged 65 years and over) and loss of productivity. Intensified prevention and effective community treatment programmes focussing on the 65 years and older age groups should be investigated (as they have the greatest potential to reduce healthcare costs).