On the imaging depth limit of photoacoustic tomography in the visible and first near-infrared windows.

It is well known that photoacoustic tomography (PAT) can circumvent the photon scattering problem in optical imaging and achieve high-contrast and high-resolution imaging at centimeter depths. However, after two decades of development, the long-standing question of the imaging depth limit of PAT in biological tissues remains unclear. Here we propose a numerical framework for evaluating the imaging depth limit of PAT in the visible and the first near-infrared windows. The established framework simulates the physical process of PAT and consists of seven modules, including tissue modelling, photon transportation, photon to ultrasound conversion, sound field propagation, signal reception, image reconstruction, and imaging depth evaluation. The framework can simulate the imaging depth limits in general tissues, such as the human breast, the human abdomen-liver tissues, and the rodent whole body and provide accurate evaluation results. The study elucidates the fundamental imaging depth limit of PAT in biological tissues and can provide useful guidance for practical experiments.

Pass-through of diesel taxes and the effect on carbon emissions: Evidence from China.

As one of the most important instruments for reducing emissions from fossil fuels, taxes have been widely used in government battles against air pollution and climate change across the world. However, the pass-through of taxes and their effect on emissions are not evident in all situations. This study investigates the pass-through of diesel consumption taxes to retail prices and estimates the consequent effect on diesel consumption and carbon emissions in China. The results show that the pass-through rate of diesel taxes in China is around 0.49. Also, there is a significant effect of an oil company's market share on the pass-through rate. Based on the pass-through rate and estimated price elasticity, we conduct further estimations of the impact on diesel consumption and carbon emissions and find that the increase in the diesel consumption tax in 2014/2015 reduces 1.64% of annual diesel consumption and 0.096% of annual carbon emissions in China.

Consumption-based greenhouse gas emissions accounting with capital stock change highlights dynamics of fast-developing countries.

Traditional consumption-based greenhouse gas emissions accounting attributed the gap between consumption-based and production-based emissions to international trade. Yet few attempts have analyzed the temporal deviation between current emissions and future consumption, which can be explained through changes in capital stock. Here we develop a dynamic model to incorporate capital stock change in consumption-based accounting. The new model is applied using global data for 1995-2009. Our results show that global emissions embodied in consumption determined by the new model are smaller than those obtained from the traditional model. The emissions embodied in global capital stock increased steadily during the period. However, capital plays very different roles in shaping consumption-based emissions for economies with different development characteristics. As a result, the dynamic model yields similar consumption-based emissions estimation for many developed countries comparing with the traditional model, but it highlights the dynamics of fast-developing countries.