scholarly journals Identifying the absolute orientation of a low-symmetry surface in real space

2014 ◽  
Vol 90 (19) ◽  
Author(s):  
Stefan Kuhn ◽  
Markus Kittelmann ◽  
Yoshiaki Sugimoto ◽  
Masayuki Abe ◽  
Angelika Kühnle ◽  
...  
Keyword(s):  
Real Space ◽  
Absolute Orientation ◽  
The Absolute ◽  
Low Symmetry ◽  
Symmetry Surface

ABS: a program to determine absolute configuration and evaluate anomalous scatterer substructure

2004 ◽  
Vol 37 (3) ◽  
pp. 498-499 ◽  
Author(s):  
Quan Hao
Keyword(s):  
Absolute Configuration ◽  
Protein Structures ◽  
Real Space ◽  
Scattering Data ◽  
Anomalous Scattering ◽  
Acta Cryst ◽  
Mad Phasing ◽  
Unknown Protein ◽  
Multi Wavelength ◽  
The Absolute

In single- or multi-wavelength anomalous dispersion (SAD/MAD) phasing, one of the essential steps is to find the absolute configuration (hand) of the anomalous scatterers. A computer program,ABS, based on an algorithm proposed by Woolfson & Yao [Acta Cryst. (1994), D50, 7–10] has been written to determine the absolute configuration by using anomalous scattering data. It also calculates a real-space figure of merit (FOM) that can be used to assess the quality of the solution for anomalous scatterer sites. TheABSprogram has been successfully applied in severalab initiophasing cases, including some previously unknown protein structures. The program is included in theCCP4suite.

scholarly journals Constraining the absolute orientation of η Carinae’s binary orbit: a 3D dynamical model for the broad [Fe iii] emission★

2012 ◽  
Vol 420 (3) ◽  
pp. 2064-2086 ◽  
Author(s):  
T. I. Madura ◽  
T. R. Gull ◽  
S. P. Owocki ◽  
J. H. Groh ◽  
A. T. Okazaki ◽  
...  
Keyword(s):  
Dynamical Model ◽  
Absolute Orientation ◽  
The Absolute ◽  
Binary Orbit

scholarly journals Mapping domains in the weak ferromagnet CoCO3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1356-C1356
Author(s):  
Guillaume Beutier ◽  
Steve Collins ◽  
Gareth Nisbet ◽  
Elena Ovchinnikova ◽  
Vladimir Dmitrienko
Keyword(s):  
Magnetic Moments ◽  
Electric Polarization ◽  
Magnetic Scattering ◽  
Zero Field ◽  
Dm Interaction ◽  
X Ray ◽  
Absolute Orientation ◽  
Weak Ferromagnet ◽  
The Absolute ◽  
Perpendicular Component

The Dzyaloshinskii-Moriya (DM) interaction [1,2] produces a perpendicular component in the coupling of neighbouring spins when the symmetry between the spins is low, or can drive a distortion of intervening atoms to create a spontaneous electric polarization in some magnetoelectrics. In weak ferromagnets, the canting of the atomic moments due to the DM interaction leads to a small parasitic ferromagnetic polarization in an otherwise antiferromagnetic structure. Recently, we determined the sign of the Dzyaloshinskii–Moriya interaction in the weak ferromagnet FeBO3 by measuring the interference between resonant x-ray scattering and non-resonant magnetic scattering at a forbidden reflection [3]. Using the same method, we determine its sign in the carbonates MnCO3 and CoCO3. These isostructural materials turn out to show opposite interference effect: further analysis is underway to confirm or not that they actually have Dzyaloshinskii–Moriya interactions of opposite signs. We go one step further and apply the same principle to map the absolute orientation (direction and sense) of the magnetisation in a crystal of CoCO3: by mapping the 009 forbidden reflection at 3 azimuthal angles, we obtain 3 projections of the local magnetisation allowing its unambiguous determination. The reconstructed magnetisation map, whose spacial resolution is about 20 µm x 20 µm (the size of the focused x-ray beam), was measured after zero-field cooling to 9 K, well below the Neel temperature. It confirms the strong in-plane anisotropy of the material, with magnetisation domains essentially along 6 orientations separated by 600. Two of them, with orientation at 600to each other (green and orange in the figure), are largely dominant on the part of the sample that was imaged. To our knowledge it is the first experimental determination of the absolute orientation of the magnetic moments in a weak ferromagnet. The figure shows the reconstructed map of magnetisation, with the direction of the local in-plane magnetisation encoded (in radians) on a periodic colour map.

scholarly journals Computationally Efficient Iterative Pose Estimation for Space Robot Based on Vision

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xiang Wu ◽  
Ning Wu
Keyword(s):  
Pose Estimation ◽  
Error Function ◽  
Outer Space ◽  
Space Robot ◽  
Space Environment ◽  
Experimental Result ◽  
Computational Time ◽  
Computationally Efficient ◽  
Absolute Orientation ◽  
The Absolute

In postestimation problem for space robot, photogrammetry has been used to determine the relative pose between an object and a camera. The calculation of the projection from two-dimensional measured data to three-dimensional models is of utmost importance in this vision-based estimation however, this process is usually time consuming, especially in the outer space environment with limited performance of hardware. This paper proposes a computationally efficient iterative algorithm for pose estimation based on vision technology. In this method, an error function is designed to estimate the object-space collinearity error, and the error is minimized iteratively for rotation matrix based on the absolute orientation information. Experimental result shows that this approach achieves comparable accuracy with the SVD-based methods; however, the computational time has been greatly reduced due to the use of the absolute orientation method.

scholarly journals Are allocentric spatial reference frames compatible with theories of Enactivism?

2017 ◽  
Author(s):  
Sabine U. König ◽  
Caspar Goeke ◽  
Tobias Meilinger ◽  
Peter König
Keyword(s):  
Reference Frames ◽  
Spatial Information ◽  
Time Pressure ◽  
Relative Orientation ◽  
Human Cognition ◽  
Absolute Orientation ◽  
Cognitive Reasoning ◽  
Orientation Task ◽  
The Absolute ◽  
Oriented Approach

AbstractTheories of Enactivism propose an action-oriented approach to understand human cognition. So far, however, empirical evidence supporting these theories has been sparse. Here, we investigate whether spatial navigation based on allocentric reference frames that are independent of the observer’s physical body can be understood within an action-oriented approach. Therefore, we performed three experiments testing the knowledge of the absolute orientation of houses and streets towards north, the relative orientation of two houses and two streets, respectively, and the location of houses towards each other in a pointing task. Our results demonstrate that under time pressure, the relative orientation of two houses can be retrieved more accurately than the absolute orientation of single houses. With infinite time for cognitive reasoning, the performance of the task using house stimuli increased greatly for the absolute orientation and surpassed the slightly improved performance in the relative orientation task. In contrast, with streets as stimuli participants performed under time pressure better in the absolute orientation task. Overall, pointing from one house to another house yielded the best performance. This suggests, firstly, that orientation and location information about houses are primarily coded in house-to-house relations, whereas cardinal information is deduced via cognitive reasoning. Secondly, orientation information for streets is preferentially coded in absolute orientations. Thus, our results suggest that spatial information about house and street orientation is coded differently and that house orientation and location is primarily learned in an action-oriented way, which is in line with an enactive framework for human cognition.

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