Phase Diagrams of Three-Dimensional Anderson and Quantum Percolation Models using Deep Three-Dimensional Convolutional Neural Network

The three-dimensional Anderson model is a well-studied model of disordered electron systems that shows the delocalization--localization transition. As in our previous papers on two- and three-dimensional (2D, 3D) quantum phase transitions [J. Phys. Soc. Jpn. {\bf 85}, 123706 (2016), {\bf 86}, 044708 (2017)], we used an image recognition algorithm based on a multilayered convolutional neural network. However, in contrast to previous papers in which 2D image recognition was used, we applied 3D image recognition to analyze entire 3D wave functions. We show that a full phase diagram of the disorder-energy plane is obtained once the 3D convolutional neural network has been trained at the band center. We further demonstrate that the full phase diagram for 3D quantum bond and site percolations can be drawn by training the 3D Anderson model at the band center.Comment: 11 pages, 5 figures. Published versio

Analytic Solutions of Teukolsky Equation in Kerr-de Sitter and Kerr-Newman-de Sitter Geometries

The analytic solution of Teukolsky equation in Kerr-de Sitter and Kerr-Newman-de Sitter geometries is presented and the properties of the solution are examined. In particular, we show that our solution satisfies the Teukolsky-Starobinsky identities explicitly and fix the relative normalization between solutions with the spin weight $s$ and $-s$.Comment: 24 pages, LaTe

Assessment of the economic impacts of climate change on agriculture in Zimbabwe : a ricardian approach

This study uses the Ricardian approach to examine the economic impact of climate change on agriculture in Zimbabwe. Net farm revenue is regressed against various climate, soil, hydrological and socio-economic variables to help determine the factors that influence variability in net farm revenues. The study is based on data from a survey of 700 smallholder farming households interviewed across the country. The empirical results show that climatic variables (temperature and precipitation) have significant effects on net farm revenues in Zimbabwe. In addition to the analysis of all farms, the study also analyzes the effects on dryland farmsand farms with irrigation. The analysis indicates that net farm revenues are affected negatively by increases in temperature and positively by increases in precipitation. The results from sensitivity analysis suggest that agricultural production in Zimbabwe's smallholder farming system is significantly constrained by climatic factors (high temperature and low rainfall). The elasticity results show that the changes in net revenue are high for dryland farming compared to farms with irrigation. The results show that farms with irrigation are more resistant to changes in climate, indicating that irrigation is an important adaptation option to help reduce the impact of further changes in climate. An overview of farmer adaptation to changing climate indicates that farmers are already using some adaptation strategies-such as dry and early planting, growing drought resistant crops, changing planting dates, and using irrigation-to cushion themselves against further anticipated adverse climatic conditions. An important policy message from the empirical findings is that there is a need to provide adequate extension information services to ensure that farmers receive up-to-date information about rainfall patterns in the forthcoming season so that they make well-informed decisions on their planting dates. Policies that increase farmer training and access to credit and aid facilities and help farmers acquire livestock and other important farm assets can help improve net farm performance. Ensuring the availability and accessibility of fertilizers and crop seeds before the onset of the next cropping season can also significantly improve net farm performance across households.Climate Change,Environmental Economics&Policies,Crops&Crop Management Systems,Agriculture&Farming Systems,Rural Development Knowledge&Information Systems