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Rotation Method (rotation + method)
Selected AbstractsFBR: a robust method to determine the basis matrix of the Bravais lattice from oscillation imagesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-2 2000Klaus Döhring The FBR (Fourier basis reconstruction) method described in this paper has been designed to determine the basis matrix of the Bravais lattice with respect to the laboratory frame of reference and without prior knowledge of cell constants, particularly for protein crystals of comparatively low quality. It is based on Fourier analysis of a three-dimensional intensity distribution in reciprocal space, which is directly obtained from observed intensity distributions, provided that they are recorded by the rotation method using a fixed X-ray wavelength, resulting in a direct-space determination of the basis vectors. After a description of the motivation and theory behind the method, it is tested by application to numerically generated images of a virtual sample crystal and to experimental data of a lysozyme crystal with well known cell constants. Finally, FBR is applied to a set of images of bacteriorhodopsin crystals suffering from strong anisotropic spot broadening; this case provided the original motivation for the present work. [source] Reply to "Comment on Aromatic-Backbone Interactions in Model ,-Helical Peptides"JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2008József Csontos Abstract In response to Van Mourik's comments on our paper (J Comput Chem 2007, 28, 1208.) we present an extended version of our rotation method. We also prove that intramolecular interaction energies as well the basis set superposition errors calculated with our rotation method are comparable with those obtained by the counterpoise method of Boys and Bernardi (Mol Phys 1970, 19, 533). In intramolecular interaction energy calculations, if the interacting groups are in proximity, our rotation method is recommended to avoid artificial interactions, which can be induced by fragmentation. © 2007 Wiley Periodicals, Inc.J Comput Chem, 2008 [source] Aspects Regarding the Conception, Modeling and Implementation of an Articulated Robot in Space with Noises and VibrationsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Virgil Ispas The authors want to conceive and to model a structure of a 6R serial modular industrial robot with six freedom degrees. Some specific points are followed: the direct geometric modelling of the robot using the matrix of rotation method, the given in 3D modelling of the robot, the presentation of its components having some possible applications in the processes of production in the spaces with noises and vibrations. The direct geometrical modelling will be determinate the relative orientation matrices, which express the position of each system Ti, (i=1-6), according to the system Ti,1, also expressing the vectors of relative position of origin Oi of the systems Ti. They will be expressed the orientation of each system Ti in account to the fixed system To attached to the robot base, the set of independent parameters of orientation then are obtained the final equation of the column vector of the generalized coordinates, which express the position and the orientation of the clamping device. The paper presents the two possible applications of the studied robot implementation in a flexible manufacturing cel for the manipulation operations of parts. The robot will be used on the other side for the execution of weld in a points applied to the car carcases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Population-specific deviations of global human craniometric variation from a neutral modelAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010John H. Relethford Abstract Past studies have revealed that much of human craniometric variation follows a neutral model of population relationships. At the same time, there is evidence for the influence of natural selection in having shaped some global diversity in craniometrics. In order to partition these effects, and to explore other potential population-specific influences, this article analyzes residuals of craniometric distances from a geographically based neutral model of population structure. W.W. Howells' global craniometric data set was used for these analyses, consisting of 57 measurements for 22 populations around the world, excluding Polynesia and Micronesia because of the relatively recent settlement of these regions. Phenotypic and geographic distances were derived between all pairs of populations. Three-dimensional multidimensional scaling configurations were obtained for both distance matrices, and compared using a Procrustes rotation method to show which populations do not fit the geographic model. This analysis revealed three major deviations: the Buriat, Greenland Inuit, and Peru. The deviations of the Buriat and Greenland Inuit appear to be related to long-term adaptation to cold environments. The Peruvian sample is more similar to other New World populations than expected based on geographic distance alone. This deviation likely reflects the evolutionarily recent movement of human populations into South America, such that these populations are further from genetic equilibrium. This same pattern is seen in South American populations in a comparative analysis of classical genetic markers, but not in a comparative analysis of STR loci, perhaps reflecting the higher mutation rate for the latter. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Simulation of X-ray frames from macromolecular crystals using a ray-tracing approachACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2009Kay Diederichs An algorithm is described which simulates a data set obtained from a protein crystal using the rotation method. The diffraction pattern of an ideal crystal is specified by the orientation of the crystal's cell axes with respect to a specified laboratory coordinate system, the distance between the crystal and the detector, the wavelength and the rotation range per frame. However, a realistic simulation of an experiment additionally requires at least a plausible physical model for crystal mosaicity and beam properties. To explore the physical basis of reflection shape and rocking-curve variation, the algorithm simulates the diffraction of a real crystal composed of mosaic blocks which is illuminated with a beam of given divergence and dispersion. Ray tracing for each reflection leads to reflection shapes and rocking curves that appear realistic. A program implementing the algorithm may be used to reproducibly generate data sets that model different physical aspects (imperfections) of the crystal and the experiment. Certain types of systematic errors of the experimental apparatus may also be simulated. Further applications include teaching and characterization of the properties of data-reduction algorithms. [source] | ||||||||||