Image Restoration using Plug-and-Play CNN MAP Denoisers

Plug-and-play denoisers can be used to perform generic image restoration tasks independent of the degradation type. These methods build on the fact that the Maximum a Posteriori (MAP) optimization can be solved using smaller sub-problems, including a MAP denoising optimization. We present the first end-to-end approach to MAP estimation for image denoising using deep neural networks. We show that our method is guaranteed to minimize the MAP denoising objective, which is then used in an optimization algorithm for generic image restoration. We provide theoretical analysis of our approach and show the quantitative performance of our method in several experiments. Our experimental results show that the proposed method can achieve 70x faster performance compared to the state-of-the-art, while maintaining the theoretical perspective of MAP.Comment: Code and models available at https://github.com/DawyD/cnn-map-denoiser . Accepted for publication in VISAPP 202

Efficient Blind-Spot Neural Network Architecture for Image Denoising

Image denoising is an essential tool in computational photography. Standard denoising techniques, which use deep neural networks at their core, require pairs of clean and noisy images for its training. If we do not possess the clean samples, we can use blind-spot neural network architectures, which estimate the pixel value based on the neighbouring pixels only. These networks thus allow training on noisy images directly, as they by-design avoid trivial solutions. Nowadays, the blind-spot is mostly achieved using shifted convolutions or serialization. We propose a novel fully convolutional network architecture that uses dilations to achieve the blind-spot property. Our network improves the performance over the prior work and achieves state-of-the-art results on established datasets

Terahertz photonic crystal quantum cascade lasers

We combine photonic crystal and quantum cascade band engineering to create an in-plane laser at terahertz frequency. We demonstrate that such photonic crystal lasers strongly improve the performances of terahertz quantum cascade material in terms of threshold current, waveguide losses, emission mode selection, tunability and maximum operation temperature. The laser operates in a slow-light regime between the M saddle point and K band-edge in reciprocal lattice. Coarse frequency control of half of a terahertz is achieved by lithographically tuning the photonic crystal period. Thanks to field assisted gain shift and cavity pulling, the single mode emission is continuously tuned over 30 GHz. (c) 2007 Optical Society of America

Challenges of diabetes prevention in the real world : results and lessons from the Melbourne diabetes prevention study

OBJECTIVE: To assess effectiveness and implementability of the public health programme Life! Taking action on diabetes in Australian people at risk of developing type 2 diabetes. RESEARCH DESIGN AND METHODS: Melbourne Diabetes Prevention Study (MDPS) was a unique study assessing effectiveness of Life! that used a randomized controlled trial design. Intervention participants with AUSDRISK score ≥15 received 1 individual and 5 structured 90 min group sessions. Controls received usual care. Outcome measures were obtained for all participants at baseline and 12 months and, additionally, for intervention participants at 3 months. Per protocol set (PPS) and intention to treat (ITT) analyses were performed. RESULTS: PPS analyses were considered more informative from our study. In PPS analyses, intervention participants significantly improved in weight (-1.13 kg, p=0.016), waist circumference (-1.35 cm, p=0.044), systolic (-5.2 mm Hg, p=0.028) and diastolic blood pressure (-3.2 mm Hg, p=0.030) compared with controls. Based on observed weight change, estimated risk of developing diabetes reduced by 9.6% in the intervention and increased by 3.3% in control participants. Absolute 5-year cardiovascular disease (CVD) risk reduced significantly for intervention participants by 0.97 percentage points from 9.35% (10.4% relative risk reduction). In control participants, the risk increased by 0.11 percentage points (1.3% relative risk increase). The net effect for the change in CVD risk was -1.08 percentage points of absolute risk (p=0.013). CONCLUSIONS: MDPS effectively reduced the risk of diabetes and CVD, but the intervention effect on weight and waist reduction was modest due to the challenges in recruiting high-risk individuals and the abbreviated intervention

Sustaining modified behaviours learnt in a diabetes prevention program in regional Australia : the role of social context

BackgroundThe Greater Green Triangle diabetes prevention program was conducted in primary health care setting of Victoria and South Australia in 2004--2006. This program demonstrated significant reductions in diabetes risk factors which were largely sustained at 18 month follow-up. The theoretical model utilised in this program achieved its outcomes through improvements in coping self-efficacy and planning. Previous evaluations have concentrated on the behavioural components of the intervention. Other variables external to the main research design may have contributed to the success factors but have yet to be identified. The objective of this evaluation was to identify the extent to which participants in a diabetes prevention program sustained lifestyle changes several years after completing the program and to identify contextual factors that contributed to sustaining changes.MethodsA qualitative evaluation was conducted. Five focus groups were held with people who had completed a diabetes prevention program, several years later to assess the degree to which they had sustained program strategies and to identify contributing factors.ResultsParticipants value the recruitment strategy. Involvement in their own risk assessment was a strong motivator. Learning new skills gave participants a sense of empowerment. Receiving regular pathology reports was a means of self-assessment and a motivator to continue. Strong family and community support contributed to personal motivation and sustained practice.ConclusionsFamily and local community supports constitute the contextual variables reported to contribute to sustained motivation after the program was completed. Behaviour modification programs can incorporate strategies to ensure these factors are recognised and if necessary, strengthened at the local level.<br /

Implementation salvage experiences from the Melbourne diabetes prevention study

Background Many public health interventions based on apparently sound evidence from randomised controlled trials encounter difficulties when being scaled up within health systems. Even under the best of circumstances, implementation is exceedingly difficult. In this paper we will describe the implementation salvage experiences from the Melbourne Diabetes Prevention Study, which is a randomised controlled trial of the effectiveness and cost-effectiveness nested in the state-wide Life! Taking Action on Diabetes program in Victoria, Australia.Discussion The Melbourne Diabetes Prevention Study sits within an evolving larger scale implementation project, the Life! program. Changes that occurred during the roll-out of that program had a direct impact on the process of conducting this trial. The issues and methods of recovery the study team encountered were conceptualised using an implementation salvage strategies framework. The specific issues the study team came across included continuity of the state funding for Life! program and structural changes to the Life! program which consisted of adjustments to eligibility criteria, referral processes, structure and content, as well as alternative program delivery for different population groups. Staff turnover, recruitment problems, setting and venue concerns, availability of potential participants and participant characteristics were also identified as evaluation roadblocks. Each issue and corresponding salvage strategy is presented.Summary The experiences of conducting such a novel trial as the preliminary Melbourne Diabetes Prevention Study have been invaluable. The lessons learnt and knowledge gained will inform the future execution of this trial in the coming years. We anticipate that these results will also be beneficial to other researchers conducting similar trials in the public health field. We recommend that researchers openly share their experiences, barriers and challenges when conducting randomised controlled trials and implementation research. We encourage them to describe the factors that may have inhibited or enhanced the desired outcomes so that the academic community can learn and expand the research foundation of implementation salvage.<br /

Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion.

Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found >2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics-similar to those associated with modern stratospheric ozone depletion over Antarctica-plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka