Acquisition techniques

Analyzers especially equipped to handle noise are required for most industrial applications. There are at least three commercially available microprocessor-based analyzers capable of acquiring data below 600 cpm. These systems use special filters and data-acquisition techniques to separate real vibration frequencies from electronic... 

The type of transducers and data acquisition techniques that you will use for the program is the final critical factor that can determine the success or failure of your program. Their accuracy, proper application and mounting will determine whether valid data will be collected. 

Conventional utilization of solution-phase NMR data acquisition techniques on solid samples yields broad, featureless spectra (Fig. 1A). The broad nature of the signal is due primarily to dipolar interactions, which do not average out to zero in the solid state, and chemical shift anisotropy (CSA), which again occurs because our compound of interest is in the solid state. Before one describes the two principal reasons for the broad, featureless spectra, it is important to understand the main interactions that a nucleus with a magnetic moment experiences when situated within a magnetic field in the solid state. In addition, manifestations of these interactions in the solid state NMR spectrum need to be discussed. 

While new data acquisition techniques under development may significantly reduce the time and increase the precision of recording diffraction patterns, it is obvious that X-ray diffraction techniques will be restricted to the study of conformations and intermediates which are stable for periods that exceed the normal half-life of these transient species. It is therefore necessary to increase the lifetime of such species so that their three-dimensional structures may be determined in the same manner as a native enzyme. 

It has long been recognized that NMR cross relaxation data can provide information on the solution conformation of biological macromolecules, mainly through the inverse sixth power dependence of the cross-relaxation rates on internuclear distance. Only recently with the advent of sophisticated two-dimensional acquisition techniques has it become possible to attempt the a-priori determination of the solution conformation... 

For the examinations of intracranial vessels the same coil systems are used as for conventional MRI of the skull. For a combined examination of intracranial and cervical vessels specially integrated coil systems are needed which can receive signals from the circle of Willis down to the aortic arch. Improvements of coil design and high frequency (HF) capabilities allow remarkable reduction in acquisition times by the use of parallel acquisition techniques (Tintera et al. 2004). 

The algorithm just discussed is a qualitative version of what must be done for each particle detectable above the noise level at both 6° and 12°. In reality the allowable 3° signal range depends on the observed 12°/6° ratio. Thus any data acquisition technique must be able to observe the 12°/6° ratio, to calculate a corresponding allowable 3°/6° ratio for comparison with that actually measured, and finally to decide on the validity of the particle based on this comparison. 

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