Oversampling

For instance, with the introduction of SR sources, particles with a radius of a few nanometers can be studied with conventional methods. This has also stimulated a new kind of microscopy, named diffraction microscopy, where the Fraunhofer diffraction intensity patterns are measured at fine intervals in reciprocal space. By means of this oversampling a computer assisted solution of the... 

The fourth factor affecting sampling frequency is efficiency, that is, to collect the minimum number of samples needed to address the key questions. The costs of collecting and analyzing samples are substantial, and the oversampling of a particular indicator would reduce resomces available for monitoring other indicators or other sites. 

Unlike the continuous zone development mechanism utilized in a planar separation experiment, comprehensive MDLC is a sequential operation in which finite volumes of eluant are injected into the next dimension column. Because of this finite volume aspect, the mechanism and consequences of sampling eluant from one column with subsequent injection into the next column must be understood. Undersampling would lead to a loss in two-dimensional resolution and oversampling would lead to excessively long run times as the second dimension column would be used in a very inefficient way. 

Key words Electron diffraction, crystallographic image processing, 3D reconstruction. Structure factors, ultrafast electron crystallography, aberration corrected electron microscope, oversampling phasing method... 

The Fourier frequency bandpass of the spectrometer is determined by the diffraction limit. In view of this fact and the Nyquist criterion, the data in the aforementioned application were oversampled. Although the Nyquist sampling rate is sufficient to represent all information in the data, it is not sufficient to represent the estimates o(k) because of the bandwidth extension that results from information implicit in the physical-realizability constraints. Although it was not shown in the original publication, it is clear from the quality of the restoration, and by analogy with other similarly bounded methods, that Fourier bandwidth extrapolation does indeed occur. This is sometimes called superresolution. The source of the extrapolation should be apparent from the Fourier transform of Eq. (13) with r(x) specified by Eq. (14). 

The CHPA commissioned a study entitled Self-Care in the New Millenium American Attitudes Toward Maintaining Personal Health and Treatment. They conducted 1505 telephone interviews in January of 2001, using random telephone numbers. African-Americans and Hispanics were oversampled to conduct in-depth subgroup analysis. Of particular interest is the finding that 96% of respondents felt confident that they could take care of their own health. This might explain why so many people want access to pharmacologically active botanicals. These products do not require a prescription and thus allow patients to treat themselves. 

Figure 1. Representation of an aircraft aerosol sampling inlet showing flow streamlines for subisokinetic, superisokinetic, and isokinetic sampling. Under subisokinetic conditions large particles will be oversampled under superisokinetic conditions small particles will be oversampled and under isokinetic conditions, the particle size distribution will be preserved.

After the anti-aliasing filter, the analog/digital converter (ADC) quantizes the continuous input into discrete levels. ADC technology has shown considerable improvement in recent years due to the development of oversampling and noise-shaping converters. However, a look at the previous technologies [Blesser, 1978] [Blesser and Kates, 1978][Fielder, 1989] will help appreciate the current state-of-the-art. 

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