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Christopher K. Butler,Jessica L. Jones 한국외국어대학교 국제지역연구센터 2016 International Area Studies Review Vol.19 No.3
Are levels of sexual violence committed by government security forces in a country prior to conflict predictive of levels of sexual violence in that country during conflict? Most of the scholarship on sexual violence focuses on the phenomenon during armed conflict, and in general the assumption made by these scholars is that conflict exacerbates the sexual violence problem. Cross-sectional analysis appears to support this assertion; however, we argue that the comparison group used by cross-sectional analyses is inappropriate for answering the question of whether conflict impacts the amount of sexual violence in a country. Instead, we propose that the appropriate comparison is between peacetime levels of sexual violence and conflict levels of sexual violence for the same country. To test this relationship, we employ data on sexual violence committed by government security forces in a sample of 170 countries for the time period 1999–2011, using a measure similar to that from Butler, Gluch, and Mitchell. Then, we use a variety of descriptive and inferential statistical tests to examine the relationship between conflict from the UCDP/PRIO Armed Conflict Dataset and the level of sexual violence in a country. We find that for cases with variation in conflict across our time period, pre-conflict levels of sexual violence are predictive of conflict levels but, contrary to the common assumption, the prediction is no change in the level of sexual violence for most cases.
Machine learning for molecular and materials science
Butler, Keith T.,Davies, Daniel W.,Cartwright, Hugh,Isayev, Olexandr,Walsh, Aron Nature Publishing Group UK 2018 Nature Vol.559 No.7715
<P>Here we summarize recent progress in machine learning for the chemical sciences. We outline machine-learning techniques that are suitable for addressing research questions in this domain, as well as future directions for the field. We envisage a future in which the design, synthesis, characterization and application of molecules and materials is accelerated by artificial intelligence.</P>
BUTLER, GEORGE B.,DO, CHOON H.,ZERNER, MICHAEL C. 순천대학교 기초과학연구소 1990 基礎科學硏究誌 Vol.1 No.-
The stereochemistry of alternating copolymers of styrene (ST) with maleic anhydride (MA) was examined by ^13C-NMR spectroscopy, and the stabilization energies and the most stable geometries of complexes and adducts between ST and MA were calculated by the PVCILO program and by INDO/1. The methine and carbonyl atoms of the MA portion and the quaternary carbon atom of the ST portion reveal defferent stereochemistries due to various polymerization conditions, suggesting that the donor-acceptor complex may participate in the copolymerization. The complex postulated according to the Diels-Alder geometry was more stable than that according to [2+2] cycloaddition geometry. It is believed that the stabilization energy is so great that the copolymerization occurs spontaneously via forming a donor-acceptor complex and adducts. The geometries of 1:1 adducts formed by endo and exo approaches in the Diels-Alder geometry mode were also calculated.
Electronic structure design for nanoporous, electrically conductive zeolitic imidazolate frameworks
Butler, Keith T.,Worrall, Stephen D.,Molloy, Christopher D.,Hendon, Christopher H.,Attfield, Martin P.,Dryfe, Robert A. W.,Walsh, Aron Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.31
<▼1><P>Electronic structure calculations are used to develop design rules for enhanced electrical conductivity in zeolitic imidazolate frameworks.</P></▼1><▼2><P>Electronic structure calculations are used to develop design rules for enhanced electrical conductivity in zeolitic imidazolate frameworks. The electrical resistivity of Co<SUP>2+</SUP> based zeolitic imidazolate frameworks has previously been found to be ∼1000 times lower than that of Zn<SUP>2+</SUP> based materials. The electrical conductivity of the frameworks can also be tuned by ligand molecule selection. Using density functional theory calculations, this controllable electrical conductivity is explained in terms of tuneable conduction band edge character, with calculations revealing the improved hybridisation and extended band character of the Co<SUP>2+</SUP> frameworks. The improvements in the methylimidazolate frameworks are understood in terms of improved frontier orbital matching between metal and ligand. The modular tuneability and previously demonstrated facile synthesis provides a route to rational design of stable framework materials for electronic applications. By outlining these design principles we provide a route to the future development of stable, electrically conductive zeolitic imidazolate frameworks.</P></▼2>
An Analytic Study of Channeled substrate planar Phased Arrays
Butler,J.K.,Oh, Hwan Sool 건국대학교 부설 산업기술연구소 1986 논문집 Vol.11 No.-
CSP 레이저들의 線形 어레이들의 모우드에 대한 발진 波長과 利得特性을 나타내었다. 어레이 모우드들의 利得값들은 배열이 인접한 요소들의 場을 이용하여 계산된 복소 결합 계수들로 결정된다. 계산결과는 거의 실수값인 場을 가지는 index guided lasers에 대하여 最高次 어레이 모우드가 쉽게 발진함을 보았다. Far field radiation pattern에서, 단지 하나의 단일 로브빔만으로 이루어지는 基本 모우드는 모든 배열 모우드들 중 가장 낮은 모우드 利得을 가진다. 最高次 모우드와 基本 모우드들 사이에서 ??보다 적은 모우드 利得差를 가지며 이것은 약 20%의 光拘束因子에 대해서, 利得差는 근사적으로 ??의 활성층 利得에 해당한다. The lasing wavelengths and gain characteristics of the modes of linear arrays of channel-substrate-planar (CSP) lasers are presented. The gain values of array modes are determined from the complex coupling coefficients calculated using the fields of neighboring elements of the array. The computations show that for index guided lasers which have fields that are almost real valued, or have only slight phase curvature, the highest order array mode will have preferred oscillation. The inphase or fundamental mode which produces only one major lobe in the far-field radiation, will have the lowest modal gain of all array modes. Some of the devices discussed have modal gain differences, between the highest and fundamental modes, of less than ??. For optical field confinement factors of about 20%, this gain difference corresponds to active layer gains of approximately ??.
Computational materials design of crystalline solids
Butler, K.,Frost, J.,Skelton, J.,Svane, K.,Walsh, A. Royal Society of Chemistry 2016 Chemical Society reviews Vol.45 No.22
<P>The modelling of materials properties and processes from first principles is becoming sufficiently accurate as to facilitate the design and testing of new systems in silico. Computational materials science is both valuable and increasingly necessary for developing novel functional materials and composites that meet the requirements of next-generation technology. A range of simulation techniques are being developed and applied to problems related to materials for energy generation, storage and conversion including solar cells, nuclear reactors, batteries, fuel cells, and catalytic systems. Such techniques may combine crystal-structure prediction (global optimisation), data mining (materials informatics) and high- throughput screening with elements of machine learning. We explore the development process associated with computational materials design, from setting the requirements and descriptors to the development and testing of new materials. As a case study, we critically review progress in the fields of thermoelectrics and photovoltaics, including the simulation of lattice thermal conductivity and the search for Pb-free hybrid halide perovskites. Finally, a number of universal chemical-design principles are advanced.</P>