69 research outputs found
Reporting participation rates in studies of non-pharmacological interventions for patients with chronic obstructive pulmonary disease: a systematic review
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Scalable Bandwidth and High-Precision Spectral Measurement by Frequency Chirped Comb
A cost-effective scan technique enabling scalable measurement range is presented by injecting a sweep RF signal of 27.5-30 GHz into an electro-optic comb generator. The 10th-order harmonic scans over an extended span (275-300 GHz) where an ultra-narrow (Q >106) resonance is well-resolved with sub-MHz resolution
"Test me and treat me" - attitudes to vitamin D deficiency and supplementation: a qualitative study
Β© 2015 BMJ Open, "Test me and treat me"-attitudes to vitamin D deficiency and supplementation: a qualitative study. This manuscript version is made available under the Creative Commons Attribution Licens
Multipoint-to-point data aggregation using a single receiver and frequency-multiplexed intensity-modulated ONUs
We demonstrate 2.5-GHz-spaced frequency multiplexing capable of aggregating 64 intensity-modulated end-users using low-speed electronic and optoelectronic components. All optical network units (ONUs) achieved high per-user capacity with dedicated optical bands, enabling future low latency applications
Pilot-aided Pump Dithering Removal in Degenerate FWM-based Optical Phase Conjugation Systems with Higher-order QAM
A pump dithering removal algorithm, based on pilot sequence-aided DSP, is proposed and experimentally validated in dual polarization 64 QAM optical phase conjugation system. A 4.2 dB SNR improvement was observed due to the SBS suppression
Implementing psychological interventions delivered by respiratory professionals for people with COPD. A stakeholder interview study.
Implementing psychological interventions in healthcare services requires an understanding of the organisational context. We conducted an interview study with UK National Health Service stakeholders to understand the barriers and facilitators for implementing psychological interventions for people with chronic obstructive pulmonary disorder (COPD). We used TANDEM as an exemplar intervention; a psychological intervention recently evaluated in a randomised controlled trial. Twenty participants providing care and/or services to people with COPD were purposively sampled from NHS primary/secondary care, and commissioning organisations. Participants were recruited via professional networks and referrals. Verbatim transcripts of semi-structured interviews were analysed using thematic analysis. Four themes were identified: (1) Living with COPD and emotional distress affects engagement with physical and psychological services; (2) Resource limitations affects service provision in COPD; (3) Provision of integrated care is important for patient well-being; and (4) Healthcare communication can be an enabler or a barrier to patient engagement. People need support with physical and psychological symptoms inherent with COPD and healthcare should be provided holistically. Respiratory healthcare professionals are considered able to provide psychologically informed approaches, but resources must be available for training, staff supervision and service integration. Communication between professionals is vital for clear understanding of an intervention's aims and content, to facilitate referrals and uptake. There was widespread commitment to integrating psychological and physical care, and support of respiratory healthcare professionals' role in delivering psychological interventions but significant barriers to implementation due to concerns around resources and cost efficiency. The current study informs future intervention development and implementation
Clock and Data Recovery-Free Data Communications Enabled by Multi-core Fiber with Low Thermal Sensitivity of Skew
Optical switching has the potential to scale the
capacity of data center networks (DCN) with a simultaneously
reduction in latency and power consumption. One of the main
challenges of optically-switched DCNs is the need for fast clock
and data recovery (CDR). Because the DCN traffic is dominated
by small packets, the CDR locking time is required to be less
than one nanosecond for achieving high network throughput.
This need for sub-nanosecond CDR locking time has motivated
research on optical clock synchronization techniques, which
deliver synchronized clock signals through optical fibers such that
the CDR modules in each transceiver only need to track the slow
change of clock phase, due to change of the time of flight as temperature varies. It is desired to remove the need for clock phase
tracking (and thereby the CDR modules) if the temperatureinduced clock phase drift can be significantly reduced, which
would reduce the power consumption and the cost of transceivers.
Previous studies have shown that the temperature-induced skew
change between multi-core fiber (MCF) cores can be forty
times lower than that of standard single mode fibers. Thus,
clock-synchronized transmission maybe possible by using two
different MCF cores for clock and data transmission, respectively,
enabling the sharing of an optical clock with stable clock phase.
To investigate the potential of MCF for CDR-free short-reach
communications, we first improve the measurement method of
the temperature dependent inter-core skew change by using a
modified delay interferometer, achieving a resolution of 3.8 femtoseconds for accurate inter-core skew measurements. Building
on the MCF measurement results, we carried out an MCF-based
clock-synchronized transmission experiment, demonstrating the
feasibility of CDR-free data communications over a temperature
range of 43 β¦C that meets DCN requirements
Optical network physical layer parameter optimization for digital backpropagation using Gaussian processes
We present a novel methodology for optimizing fiber optic network performance by determining the ideal values for attenuation, nonlinearity, and dispersion parameters in terms of achieved signal-to-noise ratio (SNR) gain from digital backpropagation (DBP). Our approach uses Gaussian process regression, a probabilistic machine learning technique, to create a computationally efficient model for mapping these parameters to the resulting SNR after applying DBP. We then use simplicial homology global optimization to find the parameter values that yield maximum SNR for the Gaussian process model within a set of a priori bounds. This approach optimizes the parameters in terms of the DBP gain at the receiver. We demonstrate the effectiveness of our method through simulation and experimental testing, achieving optimal estimates of the dispersion, nonlinearity, and attenuation parameters. Our approach also highlights the limitations of traditional one-at-a-time grid search methods and emphasizes the interpretability of the technique. This methodology has broad applications in engineering and can be used to optimize performance in various systems beyond optical networks
- β¦