Recovering Phase Information from Intensity Data(Nobel Lecture)

1986 ◽  
Vol 25 (7) ◽  
pp. 614-629 ◽  
Author(s):  
Jerome Karle
Keyword(s):  
Intensity Data ◽  
Phase Information ◽  
Nobel Lecture

Recovering Phase Information from Intensity Data

Science ◽  
1986 ◽  
Vol 232 (4752) ◽  
pp. 837-843 ◽  
Author(s):  
J. KARLE
Keyword(s):  
Intensity Data ◽  
Phase Information

Direct phase determination and refinement in the electron crystallography of small structures

1993 ◽  
Vol 51 ◽  
pp. 684-685
Author(s):  
Douglas L. Dorset ◽  
Mary P. McCourt
Keyword(s):  
Electron Diffraction ◽  
Scattering Theory ◽  
Heavy Atom ◽  
Intensity Data ◽  
Phase Information ◽  
Diffraction Intensity ◽  
Phase Determination ◽  
X Ray ◽  
Primary Extinction

The use of electron diffraction intensity data for quantitative determination of crystal structures was largely pioneered by Vainshtein, Pinsker and their co-workers, as recently reviewed, and was shown to produce results consistent with more typical X-ray structure analyses. Despite these encouraging results for a number of representative inorganic and organic materials, it is accurate to say that the technique has not been widely accepted by the crystallographic community. This is probably because, in several of the early analyses, contemporary X-ray structure results were used to provide heavy atom positions, thus providing much of the crystallographic phase information. Since it is also known that correct phases, combined with even scrambled structure factor amplitudes, will lead to a Fourier map that appears to be ’correct’, it is commonly (but incorrectly) thought that no ab initio electron diffraction determinations have been carried out for previously unsolved structures. In addition, the very complexity of n-beam dynamical scattering theory compared to ’primary extinction’ corrections has dampened enthusiasm to continue this work.

Direct phase determination in electron crystallography: small organic molecules

1992 ◽  
Vol 50 (2) ◽  
pp. 1166-1167
Author(s):  
Douglas L. Dorset
Keyword(s):  
Organic Molecules ◽  
Data Sets ◽  
Temperature Structure ◽  
3D Analysis ◽  
Intensity Data ◽  
Electron Crystallography ◽  
Phase Determination ◽  
Measured Intensity ◽  
3D Data

The quantitative use of electron diffraction intensity data for the determination of crystal structures represents the pioneering achievement in the electron crystallography of organic molecules, an effort largely begun by B. K. Vainshtein and his co-workers. However, despite numerous representative structure analyses yielding results consistent with X-ray determination, this entire effort was viewed with considerable mistrust by many crystallographers. This was no doubt due to the rather high crystallographic R-factors reported for some structures and, more importantly, the failure to convince many skeptics that the measured intensity data were adequate for ab initio structure determinations.We have recently demonstrated the utility of these data sets for structure analyses by direct phase determination based on the probabilistic estimate of three- and four-phase structure invariant sums. Examples include the structure of diketopiperazine using Vainshtein's 3D data, a similar 3D analysis of the room temperature structure of thiourea, and a zonal determination of the urea structure, the latter also based on data collected by the Moscow group.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Rational Expectations and Inflation

2017 ◽  
Author(s):  
Thomas J. Sargent
Keyword(s):  
World War I ◽  
French Revolution ◽  
Rational Expectations ◽  
Ronald Reagan ◽  
Fiscal Policies ◽  
Economic Policies ◽  
Budget Deficits ◽  
Nobel Lecture ◽  
Economic Decisions ◽  
The French Revolution

This collection of essays uses the lens of rational expectations theory to examine how governments anticipate and plan for inflation, and provides insight into the pioneering research for which the author was awarded the 2011 Nobel Prize in economics. Rational expectations theory is based on the simple premise that people will use all the information available to them in making economic decisions, yet applying the theory to macroeconomics and econometrics is technically demanding. This book engages with practical problems in economics in a less formal, noneconometric way, demonstrating how rational expectations can satisfactorily interpret a range of historical and contemporary events. It focuses on periods of actual or threatened depreciation in the value of a nation's currency. Drawing on historical attempts to counter inflation, from the French Revolution and the aftermath of World War I to the economic policies of Margaret Thatcher and Ronald Reagan, the book finds that there is no purely monetary cure for inflation; rather, monetary and fiscal policies must be coordinated. This fully expanded edition includes the author's 2011 Nobel lecture, “United States Then, Europe Now.” It also features new articles on the macroeconomics of the French Revolution and government budget deficits.

Accurate Synchronization of Speech and EGG Signal Using Phase Information

2017 ◽  
Author(s):  
Sunil Kumar S.B. ◽  
K. Sreenivasa Rao ◽  
Tanumay Mandal
Keyword(s):  
Phase Information ◽  
Egg Signal

3D localization for subcentimeter-sized devices

2021 ◽  
Vol 64 (3) ◽  
pp. 117-125
Author(s):  
Rajalakshmi Nandakumar ◽  
Vikram Iyer ◽  
Shyamnath Gollakota
Keyword(s):  
Metropolitan Area ◽  
Ultra Wideband ◽  
Phase Information ◽  
Noise Floor ◽  
Localization System ◽  
Coin Cell ◽  
3D Localization ◽  
Button Cell ◽  
Iot Devices ◽  
5 Ghz

The vision of tracking small IoT devices runs into the reality of localization technologies---today it is difficult to continuously track objects through walls in homes and warehouses on a coin cell battery. Although Wi-Fi and ultra-wideband radios can provide tracking through walls, they do not last more than a month on small coin and button cell batteries because they consume tens of milliwatts of power. We present the first localization system that consumes microwatts of power at a mobile device and can be localized across multiple rooms in settings such as homes and hospitals. To this end, we introduce a multiband backscatter prototype that operates across 900 MHz, 2.4 GHz, and 5 GHz and can extract the backscatter phase information from signals that are below the noise floor. We build subcentimeter-sized prototypes that consume 93 μW and could last five to ten years on button cell batteries. We achieved ranges of up to 60 m away from the AP and accuracies of 2, 12, 50, and 145 cm at 1, 5, 30, and 60 m, respectively. To demonstrate the potential of our design, we deploy it in two real-world scenarios: five homes in a metropolitan area and the surgery wing of a hospital in patient pre-op and post-op rooms as well as storage facilities.

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