Difference mode EXELFS with parallel-detection EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1262-1263
Author(s):  
Michael K. Kundmann ◽  
Ondrej L. Krivanek
Keyword(s):  
Edge Detection ◽  
Important Distinction ◽  
Edge Structure ◽  
Parallel Detection ◽  
Gain Variation ◽  
Ideal Solutions ◽  
Detector Cell ◽  
The Difference ◽  
Elemental Detection ◽  
Partial Correction

Parallel detection has greatly improved the elemental detection sensitivities attainable with EELS. An important element of this advance has been the development of differencing techniques which circumvent limitations imposed by the channel-to-channel gain variation of parallel detectors. The gain variation problem is particularly severe for detection of the subtle post-threshold structure comprising the EXELFS signal. Although correction techniques such as gain averaging or normalization can yield useful EXELFS signals, these are not ideal solutions. The former is a partial throwback to serial detection and the latter can only achieve partial correction because of detector cell inhomogeneities. We consider here the feasibility of using the difference method to efficiently and accurately measure the EXELFS signal.An important distinction between the edge-detection and EXELFS cases lies in the energy-space periodicities which comprise the two signals. Edge detection involves the near-edge structure and its well-defined, shortperiod (5-10 eV) oscillations. On the other hand, EXELFS has continuously changing long-period oscillations (∼10-100 eV).

Acquisition of EELS spectra for high-resolution spectroscopy

1993 ◽  
Vol 51 ◽  
pp. 578-579
Author(s):  
Maoxu Qian ◽  
Mehmet Sarikaya ◽  
Edward A. Stern
Keyword(s):  
Energy Loss ◽  
Detection System ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Short Report ◽  
Edge Structure ◽  
High Background ◽  
Gain Variation ◽  
Sufficient Energy ◽  
On Line

It is difficult, in general, to perform quantitative EELS to determine, for example, relative or absolute compositions of elements with relatively high atomic numbers (using, e.g., K edge energies from 500 eV to 2000 eV), to study ELNES (energy loss near edge structure) signal using the white lines to determine oxidation states, and to analyze EXELFS (extended energy loss fine structure) to study short range ordering. In all these cases, it is essential to have high signal-to-noise (S/N) ratio (low systematical error) with high overall counts, and sufficient energy resolution (∽ 1 eV), requirements which are, in general, difficult to attain. The reason is mainly due to three important inherent limitations in spectrum acquisition with EELS in the TEM. These are (i) large intrinsic background in EELS spectra, (ii) channel-to-channel gain variation (CCGV) in the parallel detection system, and (iii) difficulties in obtaining statistically high total counts (∽106) per channel (CH). Except the high background in the EELS spectrum, the last two limitations may be circumvented, and the S/N ratio may be attained by the improvement in the on-line acquisition procedures. This short report addresses such procedures.

scholarly journals Towards a Validation Methodology for Macroeconomic Agent-Based Models

2021 ◽  
Author(s):  
Sebastiaan Tieleman
Keyword(s):  
Emergent Properties ◽  
Agent Based Models ◽  
Important Distinction ◽  
Agent Based ◽  
Model Classification ◽  
Classification Framework ◽  
The Difference ◽  
To Come

AbstractAgent-based models provide a promising new tool in macroeconomic research. Questions have been raised, however, regarding the validity of such models. A methodology of macroeconomic agent-based model (MABM) validation, that provides a deeper understanding of validation practices, is required. This paper takes steps towards such a methodology by connecting three elements. First, is a foundation of model validation in general. Second is a classification of models dependent on how the model is validated. An important distinction in this classification is the difference between mechanism and target validation. Third, is a framework that revolves around the relationship between the structure of models of complex systems with emergent properties and validation in practice. Important in this framework is to consider MABMs as modelling multiple non-trivial levels. Connecting these three elements provides us with a methodology of the validation of MABMs and allows us to come to the following conclusions regarding MABM validation. First, in MABMs, mechanisms at a lower level are distinct from, but provide input to higher levels of mechanisms. Since mechanisms at different levels are validated in different ways we can come to a specific characterization of MABMs within the model classification framework. Second, because the mechanisms of MABMs are validated in a direct way at the level of the agent, MABMs can be seen as a move towards a more realist approach to modelling compared to DSGE.

The Secular City in Cross-Cultural Perspective

2013 ◽  
Author(s):  
Harvey Cox
Keyword(s):  
Western Europe ◽  
World Wide ◽  
The United States ◽  
New Delhi ◽  
Cultural Perspective ◽  
Important Distinction ◽  
The Rich ◽  
The Difference ◽  
Historical Movement ◽  
Urban Civilization

This chapter illustrates the rich variety of the secularization process, looking at four cities representing four distinctive regions. These cities include New Delhi, Rome, Prague, and Boston. They represent the march of secularization and urbanization in, respectively, Southeast Asia, Western Europe, Eastern Europe, and the United States. Each of the four has felt the pressure of secularization differently, in part because of their diverse histories. The careers of these cities prove that the emergence of a world-wide urban civilization need not obliterate the distinctive coloration of particular cities or erase the uniqueness of their character. The chapter also demonstrates an important distinction made in an earlier chapter—the difference between secularization as a historical movement and secularism as ideology.

Introduction

The Good Kill ◽  
2021 ◽  
pp. 1-14
Author(s):  
Marc LiVecche
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Moral Injury ◽  
Psychic Trauma ◽  
Important Distinction ◽  
Critical Understanding ◽  
Just War Tradition ◽  
The Difference ◽  
Definition Of ◽  
Realist Perspective

The introduction provides an overview of the book’s content. Opening with an illustration attending the issue of killing in war, it gestures toward the important link between killing and psychic trauma. To interrogate this linkage, it introduces critical distinctions between different kinds of killing, divergent warfighter attitudes toward killing, various Christian responses to killing and war, and between moral injury and posttraumatic stress disorder. Because it endorses a definition of moral injury as a psychic trauma that occurs when one does something that transgresses a deeply held moral norm, it stresses a critical understanding of the difference between grief and guilt and posits an important distinction between “moral injury” and what it terms “moral bruising.” To elaborate on these distinctions, it introduces the just war tradition as a Christian realist perspective best able to help warfighters navigate the morally bruising battlefield without becoming irreparably injured morally.

Rutile- and anatase-type temperature-dependent pre-edge peak intensities in K-edge XANES spectra for AO (A = Mn), A 2O3 (A = Sc, Cr and Mn) and AO2 (A = Ti and V)

2018 ◽  
Vol 25 (4) ◽  
pp. 1129-1134 ◽  
Author(s):  
Tsubasa Tobase ◽  
Akira Yoshiasa ◽  
Tatsuya Hiratoko ◽  
Akihiko Nakatsuka
Keyword(s):  
Temperature Dependence ◽  
Difference Spectrum ◽  
True Temperature ◽  
Energy Position ◽  
Edge Structure ◽  
Peak Intensity ◽  
Transition Metal Element ◽  
Peak Energy ◽  
Bending Mode ◽  
The Difference

Pre-edge peaks in 3d transition-metal element (Sc, Ti, V, Cr and Mn) K-edge XANES (X-ray absorption near-edge structure) spectra in AO2 (A = Ti and V), A 2O3 (A = Sc, Cr and Mn) and AO (A = Mn) are measured at various temperatures. Quantitative comparisons for the XANES spectra were investigated by using absorption intensity invariant point normalization. The energy position of the difference peak (D peak) is obtained from the difference between the low- and high-temperature XANES spectra. There are two kinds of temperature dependence for pre-edge peak intensity: rutile- and anatase-type. The true temperature dependence of a transition to each orbital is obtained from the difference spectrum. In both anatase and rutile, the pre-edge peak positions of A2 and A3 are clearly different from the D1- and D2-peak positions. The A1 peak-top energies in both phases of VO2 differ from the D1 peak-top energies. The D-peak energy position determined by the difference spectrum should represent one of the true energies for the transition to an independent orbital. The peak-top positions for pre-edge peaks in XANES do not always represent the true energy for independent transitions to orbitals because several orbital transitions overlap with similar energies. This work suggests that deformation vibration (bending mode) is effective in determining the temperature dependence for the D-peak intensity.

Effect of thickness variations on EELS spatial-difference profiles

1996 ◽  
Vol 54 ◽  
pp. 564-565
Author(s):  
J. Bruley ◽  
D. B. Williams
Keyword(s):  
Difference Spectrum ◽  
Spatial Difference ◽  
Probe Position ◽  
Difference Spectra ◽  
Characteristic Structure ◽  
Edge Structure ◽  
Dependent Signal ◽  
The Difference ◽  
Thickness Variations ◽  
Energy Dependent

This paper concerns the influence of sample thickness on spatial-difference spectra, and seeks to identify if an interface dependent signal may be generated as an artifact of grain boundary grooving. The spatial-difference profiling technique may be used to identify variations in composition and electronic structure across interfaces at sub-nanometer length scales. The signal-to-background ratios and hence visibility of small changes to the near-edge structure and edge intensities are enhanced using this technique by removing intense energy dependent backgrounds. These backgrounds are assumed to be only slowly varying with respect to the electron probe position. A spatial-difference spectrum is generated from the difference between two spectra after suitable normalization or scaling. This scaling is achieved by either matching intensities of the background prior to a characteristic absorption edge (for compositional profiles) or by normalizing to some characteristic structure of the near-edge structure (for bonding profiles). The latter is performed typically after subtraction of a smooth power-law background modeled in the region immediately preceding the edge.

Languages and langages

2020 ◽  
pp. 19-36
Keyword(s):  
Modern World ◽  
Important Distinction ◽  
The World ◽  
Oral Expression ◽  
The Caribbean ◽  
The Difference ◽  
The Way

This chapter in fact covers a range of subjects: the need for literature to express the ‘world totality’; the difference between ‘atavistic’ and ‘composite’ (i.e., creolized) communities; the ‘Chaos-world’ (Glissant’s term for the unpredictability that he sees as characterizing the modern world); the transition from written to oral expression; and the rejection of ‘monolingualism’ – i.e., the recognition that even if we only speak one language, we nevertheless write ‘in the presence of all the world’s languages’, and this awareness transforms the way we use our own language. There is an important distinction between a language (Creole, French, English, etc.) and a langage (for which there is no equivalent term in English), which is defined as the speaker’s or writer’s subjective relationship to the language that he or she uses. Speakers of different languages can share the same langage: thus there is a langage that is common to the Caribbean as a whole. Finally, Glissant discusses the art and the importance of translation.

Progress in parallel-detection electron energy loss spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 660-661
Author(s):  
Ondrej L. Krivanek
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Dynamic Range ◽  
Detection Efficiency ◽  
Acquisition Time ◽  
Electron Spectrometer ◽  
Parallel Detection ◽  
Gain Variation ◽  
Electron Energy Loss ◽  
Spectral Intensities

Parallel-detection electron energy loss spectrometers improve the detection efficiency by several hundred times compared to the traditional serial-detection spectrometers, but they have their own set of difficulties, such as the limited dynamic range of solid state detectors, the possibility of stray reflections of the intense zero loss beam giving rise to spurious background, and channel-to-channel gain variation. Fortunately, none of these difficulties is turning out to be insoluble. Here we report on improvements of the Gatan 666 parallel detection electron spectrometer in the areas of increasing the dynamic range of the detector, and in eliminating stray reflections.The increase in the dynamic range of the detector was needed especially for low energy losses (high spectral intensities), which usually saturated the detector even at the minimum acquisition time of 12 msecs. Accordingly, we have developed an electron attenuator which uses a magnetic dipole to sweep the spectrum across the detector perpendicular to the dispersion direction (Fig. 1).

The Time of Reenactment in Basse Danse and Bassadanza

2017 ◽  
Author(s):  
Seeta Chaganti
Keyword(s):  
Fifteenth Century ◽  
Temporal Structure ◽  
Historical Reconstruction ◽  
Temporal Experience ◽  
Important Distinction ◽  
The Future ◽  
The Difference

Fifteenth-century dance manuals reveal an important distinction between the work of historical reconstruction and that of theoretical reenactment. Basse danse and bassadanza manuals clarify that the difference between reenactment and reconstruction is a difference in temporal experience. When we use these documents simply to reconstruct—to piece together and attempt to replicate a past step pattern—we discern in the manuals and in their dances an anticipatory temporality that privileges looking toward the future. When, however, we approach these texts through the theoretical discourse of reenactment, we discover a different kind of time. It is recursive, multidirectional, and far more layered than the anticipatory model that the dance instructions appear on the surface to adopt. When this more complex temporal structure becomes visible, this chapter argues, we recognize how these early dances and their instruction manuals theorize their own uses of time and thus their own reenactment.

scholarly journals Feature Point Matching Method Based on Consistent Edge Structures for Infrared and Visible Images

2020 ◽  
Vol 10 (7) ◽  
pp. 2302
Author(s):  
Qi Wang ◽  
Xiang Gao ◽  
Fan Wang ◽  
Zhihang Ji ◽  
Xiaopeng Hu
Keyword(s):  
Feature Detection ◽  
Edge Length ◽  
Superior Performance ◽  
Matching Accuracy ◽  
Visible Image ◽  
Edge Structure ◽  
Image Match ◽  
Visible Images ◽  
The Difference ◽  
Public Datasets

Infrared and visible image match is an important research topic in the field of multi-modality image processing. Due to the difference of image contents like pixel intensities and gradients caused by disparate spectrums, it is a great challenge for infrared and visible image match in terms of the detection repeatability and the matching accuracy. To improve the matching performance, a feature detection and description method based on consistent edge structures of images (DDCE) is proposed in this paper. First, consistent edge structures are detected to obtain similar contents of infrared and visible images. Second, common feature points of infrared and visible images are extracted based on the consistent edge structures. Third, feature descriptions are established according to the edge structure attributes including edge length and edge orientation. Lastly, feature correspondences are calculated according to the distance of feature descriptions. Due to the utilization of consistent edge structures of infrared and visible images, the proposed DDCE method can improve the detection repeatability and the matching accuracy. DDCE is evaluated on two public datasets and are compared with several state-of-the-art methods. Experimental results demonstrate that DDCE can achieve superior performance against other methods for infrared and visible image match.

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