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We propose a homogenization scheme for metamaterials that utilizes causality to determine their effective parameters. By requiring the Kramers-Kronig causality condition in the homogenization of metamaterials, we show that the effective parameters can be chosen uniquely, in contrast to the conventional parameter retrieval method which has unavoidable phase ambiguity arising from the multivalued logarithm function. We demonstrate that the effective thickness of metamaterials can also be determined to a specific value by saturating the minimum-error condition for the causality restriction. Our causal homogenization provides a robust and accurate characterization method for metamaterials.

In 2018, the OECD Development Assistance Committee (DAC) created a new policy marker for disaster risk reduction (DRR) to help member states to monitor and report the progress made on the mainstreaming of DRR into their development activities. Drawing on this DRR marker, this study found that DAC members' DRR mainstreaming remains in the incipient stage, with a significant gap between rhetoric and action. Important areas for improvement include a more comprehensive understanding of disaster risk; increased funding for activities principally targeting DRR, larger scale projects; enhanced financial stability without compromising other development objectives; and further integration of DRR and climate change adaption into development projects. [ABSTRACT FROM AUTHOR]

This study explores how the Japanese and Korean governments use multi-bi aid to complement their bilateral aid and compares their allocation behaviors. As opposed to traditional multilateral aid, multi-bi aid is earmarked for a specific country, project, region, sector, or theme. Japan—a traditional leading donor—and Korea—a small but growing donor—are considerably different in terms of their ODA history and size; although, they are comparable in meaningful manners in terms of their level of cooperation with multilateral organizations. Over the past 10 years, both countries used the multilateral system to a significantly lesser extent yet showed a higher proportion of earmarked funding within multilateral aid compared to the average DAC donor. This study identified more similarities than differences between Japan and South Korea—both countries commit a large proportion of their multi-bi to fragile and conflict-affected states, countries under-represented in their bilateral aid programs. Accordingly, a large proportion of their aid has been channeled through multilateral organizations leading the sectors that are not prioritized with their bilateral aid. Overall, this study identified strong complementarities between the composition of Japan's and Korea's bilateral and multi-bi aid. [ABSTRACT FROM AUTHOR]