Journal ArticleDOI
Unit Cell Refinement from Powder Diffraction Data: The Use of Regression Diagnostics
Tim Holland,Simon A. T. Redfern +1 more
TLDR
The use of regression diagnostics combined with nonlinear least-squares to refine cell parameters from powder diffraction data, presenting a method which minimizes residuals in the experimentallydetermined quantity.Abstract:
We discuss the use of regression diagnostics combined with nonlinear least-squares to refine cell parameters from powder diffraction data, presenting a method which minimizes residuals in the experimentallydetermined quantity (usually 20hkt or energy, Ehkt). Regression diagnostics, particularly deletion diagnostics, are invaluable in detection of outliers and influential data which could be deleterious to the regressed results. The usual practice of simple inspection of calculated residuals alone often fails to detect the seriously deleterious outliers in a dataset, because bare residuals provide no information on the leverage (sensitivity) of the datum concerned. The regression diagnostics which predict the change expected in each cell constant upon deletion of each observation (hkl reflection) are particularly valuable in assessing the sensitivity of the calculated results to individual reflections. A new computer program, implementing nonlinear regression methods and providing the diagnostic output, is described. I~YWORDS: powder diffraction, regression diagnostics, lattice parameters, computer program.read more
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Journal ArticleDOI
Regression Diagnostics: Identifying Influential Data and Sources of Collinearity
TL;DR: This chapter discusses Detecting Influential Observations and Outliers, a method for assessing Collinearity, and its applications in medicine and science.
Journal ArticleDOI
Luminescence Properties of a Red Phosphor, CaAlSiN3 : Eu2 + , for White Light-Emitting Diodes
TL;DR: In this article, the authors developed a new red phosphor, CaAlSiN 3 :Eu 2+, which has a broad excitation band extended from UV region to 590 nm.
Journal ArticleDOI
Itokawa Dust Particles: A Direct Link Between S-Type Asteroids and Ordinary Chondrites
Tomoki Nakamura,Takaaki Noguchi,Masahiko Tanaka,Michael E. Zolensky,Makoto Kimura,Akira Tsuchiyama,Aiko Nakato,T. Ogami,Hatsumi Ishida,Masayuki Uesugi,Toru Yada,Kei Shirai,Akio Fujimura,Ryuji Okazaki,Scott A. Sandford,Yukihiro Ishibashi,Masanao Abe,Tatsuaki Okada,Munetaka Ueno,Toshifumi Mukai,Makoto Yoshikawa,Jun'ichiro Kawaguchi +21 more
TL;DR: Laboratory analysis of samples returned from an asteroid establishes a direct link between asteroids and meteorites and provides clues to the complex history of the asteroid and its surface.
Journal ArticleDOI
Tunable Blue-Green Color Emission and Energy Transfer of Ca2Al3O6F:Ce3+,Tb3+ Phosphors for Near-UV White LEDs
Zhiguo Xia,Ru-Shi Liu +1 more
TL;DR: In this paper, a series of new luminescent emission-tunable phosphors Ca2Al3O6F:Ce3+,Tb3+ have been synthesized by a high temperature solid-state reaction.
Journal ArticleDOI
Large gem diamonds from metallic liquid in Earth’s deep mantle
Evan M. Smith,Steven B. Shirey,Fabrizio Nestola,Emma S. Bullock,Jianhua Wang,Stephen H. Richardson,Wuyi Wang +6 more
TL;DR: It is reported that large, exceptional gem diamonds like the Cullinan, Constellation, and Koh-i-Noor carry direct evidence of crystallization from a redox-sensitive metallic liquid phase in the deep mantle, verifying previous predictions that Earth has highly reducing deep mantle regions capable of precipitating a metallic iron phase that contains dissolved carbon and hydrogen.
References
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Regression Diagnostics: Identifying Influential Data and Sources of Collinearity
TL;DR: In this article, the authors present a method for detecting and assessing Collinearity of observations and outliers in the context of extensions to the Wikipedia corpus, based on the concept of Influential Observations.
Journal ArticleDOI
Regression Diagnostics: Identifying Influential Data and Sources of Collinearity
TL;DR: This chapter discusses Detecting Influential Observations and Outliers, a method for assessing Collinearity, and its applications in medicine and science.
Journal ArticleDOI
Regression Diagnostics: Identifying Influential Data and Sources of Collinearity.
Journal ArticleDOI
Regression diagnostics and robust regression in geothermometer/geobarometer calibration: the garnet-clinopyroxene geothermometer revisited
TL;DR: In this paper, a new geothermometer equation for garnet-clinopyroxene Fe-Mg exchange was derived using robust regression and based on all the data.
Journal ArticleDOI
Precision Lattice Constants from X‐Ray Powder Photographs
TL;DR: In this article, a general method for the calculation of lattice constants from powder photographs is given, in which there is taken into account the various systematic errors inevitable in such photographs, including radius errors, film shrinkage, absorption, eccentricity and finite slit height.