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Photoacoustic (PA) imaging combines optical excitation with ultrasonic detection to achieve high-resolution imaging of biological samples. A high-energy pulsed laser is often used for imaging at multi-centimeter depths in tissue. These lasers typically have a low pulse repetition rate, so to acquire images in real-time, only one pulse of the laser can be used per image. This single pulse necessitates the use of many individual detectors and receive electronics to adequately record the resulting acoustic waves and form an image. Such requirements make many PA imaging systems both costly and complex. This investigation proposes and models a method of volumetric PA imaging using a state-of-the-art compressed sensing approach to achieve real-time acquisition of the initial pressure distribution (IPD) at a reduced level of cost and complexity. In particular, a single exposure of an optical image sensor is used to capture an entire Fabry–Pérot interferometric acoustic sensor. Time resolved encoding as achieved through spatial sweeping with a galvanometer. This optical system further makes use of a random binary mask to set a predetermined subset of pixels to zero, thus enabling recovery of the time-resolved signals. The Two-Step Iterative Shrinking and Thresholding algorithm is used to reconstruct the IPD, harnessing the sparsity naturally occurring in the IPD as well as the additional structure provided by the binary mask. We conduct experiments on simulated data and analyze the performance of our new approach.

We introduce a method for volumetric photoacoustic imaging from a single laser shot using compressive sensing. We demonstrate the accuracy and efficiency of a 3D pressure distribution reconstruction.

The Fogg Behavior Model (FBM) is a new framework which posits that behavior happens when three factors - motivation, ability, and a prompt - occur in the same moment. The FBM categorizes people into four groups based on motivation and ability and posits that those with high motivation and high ability will adopt a behavior when prompted. Two rounds of panel survey data from 617 married men in urban Pakistan were used to test this hypothesis. Multilevel mixed-effects logistic regression was used for the analysis. The results show the relationships between ability, motivation, the prompt and condom use to be as hypothesized by the FBM. After adjustment for a range of variables including fertility desires, education, and household wealth, the odds of condom use among men with high motivation and high ability were 34 times higher than the odds of condom use among men with low motivation and low ability. Moreover, the association between the prompt and condom use operated through increased motivation and ability. The FBM has potential for use in the design and evaluation of behavior change interventions in developing countries.

Introduction In 2014, the Government of Thailand recommended pre‐exposure prophylaxis (PrEP) as an additional HIV prevention programme within Thailand's National Guidelines on HIV/AIDS Treatment Prevention. However, to date implementation and uptake of PrEP programmes have been limited, and evidence on the costs and the epidemiological and economic impact is not available. Methods We estimated the costs associated with PrEP provision among men having sex with men (MSM) participating in a facility‐based, prospective observational cohort study: the Test, Treat and Prevent HIV Programme in Thailand. We created a suite of scenarios to estimate the cost‐effectiveness of PrEP and sensitivity of the results to the model input parameters, including PrEP programme effectiveness, PrEP uptake among high‐risk and low‐risk MSM, baseline and future antiretroviral therapy (ART) coverage, condom use, unit cost of delivering PrEP, and the discount rate. Results Drug costs accounted for 82.5% of the total cost of providing PrEP, followed by lab testing (8.2%) and personnel costs (7.8%). The estimated costs of providing the PrEP package in accordance with the national recommendation ranges from US$223 to US$311 per person per year. Based on our modelling results, we estimate that PrEP would be cost‐effective when provided to either high‐risk or all MSM. However, we found that the programme would be approximately 32% more cost‐effective if offered to high‐risk MSM than it would be if offered to all MSM, with an incremental cost‐effectiveness ratio of US$4,836 per disability‐adjusted life years (DALY) averted and US$7,089 per DALY averted respectively. Cost‐effectiveness acceptability curves demonstrate that 80% of scenarios would be cost‐effective when PrEP is provided solely to higher‐risk MSM. Conclusion We provide the first estimates on cost and cost‐effectiveness of PrEP in the Asia‐Pacific region, and offer insights on how to deliver PrEP in combination with ART. While the high drug cost poses a budgeting challenge, incorporating PrEP delivery into an existing ART programme could be a cost‐effective strategy to prevent HIV infections among MSM in Thailand.