Streamers in air splitting into three branches

We investigate the branching of positive streamers in air and present the first systematic investigation of splitting into more than two branches. We study discharges in 100 mbar artificial air that is exposed to voltage pulses of 10 kV applied to a needle electrode 160 mm above a grounded plate. By imaging the discharge with two cameras from three angles, we establish that about every 200th branching event is a branching into three. Branching into three occurs more frequently for the relatively thicker streamers. In fact, we find that the surface of the total streamer cross-sections before and after a branching event is roughly the same.Comment: 6 pages, 7 figure

Climate Policy and Trade in Polluting Technologies

This paper studies international trade in equipment used in the combustion of fossil fuels. Informed by a theoretical analysis, we identify a type of technology leakage hitherto unexplored in the literature: a country’s export of combustion equipment tends to increase, all else equal, in the stringency of its climate policy. We test this prediction by estimating the impact of carbon pricing on international trade in combustion equipment using detailed data on bilateral trade and domestic carbon prices for the period 1995–2021. Our estimates reveal a robust positive association between the stringency of climate policies and exports of combustion equipment, providing clear evidence for the existence of technology leakage. We argue that standard policies to mitigate carbon leakage are unlikely to prevent technology leakage, raising novel policy questions

The future of the East Asian political economy: China, Japan and regional integration

As international newspaper headlines increasingly focus on energy and security issues, one could almost forget that the main ties that bind states and regions of the world together are trade and economic relations

Design and Fabrication of Cell-laden Gelatin Methacrylated Hydrogel Scaffold for Improving Biotransportation

One of the main goals of Tissue Engineering (TE), which has been developed rapidly over the recent years, is to re-create organs or tissues in vitro or in vivo with mimicked the anatomy and functions of body systems. Nowadays, replacing damaged tissues or organs has been a main focus in this field for addressing a significant shortage of donor tissues. Vascularisation plays a crucial role in supplying cells and tissue with essential oxygen and nutrients and removing waste products from the engineered tissue constructs. Any issue in nutrient perfusion and mass transport could significantly restrict construct development to dimensions smaller than clinically useful size, thus limiting the ability for in vivo integration. The main objectives of this study are to develop a novel framework for computational design using topology optimisation and microfabrication of 3D scaffolds using gelatin-based hydrogels (GelMa), allowing artificial vascularisation in vitro for testing if the framework is valid through the investigation into cellular viability inside the construct. In this thesis, computational models were first generated to simulate oxygen transport through solving the diffusion equation. The diffusion models are then used to optimise scaffold topology. By means of microfabrication technologies, hydrogel-based constructs were fabricated to prototype the sophisticated scaffolds. Cellular viability study was also performed to validate computational simulations and design. The results showed a higher cellular survival rate in optimally patterned constructs than the control. In summary, the work presented here is not only technically simple and cost-effective, but also establishes an effective approach to the design and fabrication of a vascularised biodegradable and scaffold-free constructs. The proposed methodology will be of considerable implication for engineering bulk tissue constructs which require sufficient ongoing vascularization in the future

Logarithmic mathematical morphology: a new framework adaptive to illumination changes

A new set of mathematical morphology (MM) operators adaptive to illumination changes caused by variation of exposure time or light intensity is defined thanks to the Logarithmic Image Processing (LIP) model. This model based on the physics of acquisition is consistent with human vision. The fundamental operators, the logarithmic-dilation and the logarithmic-erosion, are defined with the LIP-addition of a structuring function. The combination of these two adjunct operators gives morphological filters, namely the logarithmic-opening and closing, useful for pattern recognition. The mathematical relation existing between ``classical'' dilation and erosion and their logarithmic-versions is established facilitating their implementation. Results on simulated and real images show that logarithmic-MM is more efficient on low-contrasted information than ``classical'' MM