Direct standardization

In the direct standardization introduced by Wang et al. [42] one finds the transformation needed to transfer spectra from the child instrument to the parent instrument using a multivariate calibration model for the transformation matrix = ZgF. The transformation matrix F (qxq) translates spectra Zg that are actually measured on the child instrument B into spectra Z that appear as if they were measured on instrument A. Predictions are then obtained by applying the old calibration model to these simulated spectra Z ... 

Piece goods, detersive systems for, <5 413t Piecewise Direct Standardization, 6 67 Pierce s Disease, 26 309... 

Standardizing the spectral response is mathematically more complex than standardizing the calibration models but provides better results as it allows slight spectral differences - the most common between very similar instruments - to be corrected via simple calculations. More marked differences can be accommodated with more complex and specific algorithms. This approach compares spectra recorded on different instruments, which are used to derive a mathematical equation, allowing their spectral response to be mutually correlated. The equation is then used to correct the new spectra recorded on the slave, which are thus made more similar to those obtained with the master. The simplest methods used in this context are of the univariate type, which correlate each wavelength in two spectra in a direct, simple manner. These methods, however, are only effective with very simple spectral differences. On the other hand, multivariate methods allow the construction of matrices correlating bodies of spectra recorded on different instruments for the above-described purpose. The most frequent choice in this context is piecewise direct standardization... 

PDS), which is based on the use of moving windows that allow corrections to be applied in specihc spectral regions. Other methods used for this purpose include simple wavelength standardization (SWS), multivariate wavelength standardization (MWS) and direct standardization (DS). 

CEC capillary electochromotography DS design space direct standardization... 

The compoimding effect of so many added burdens from all directions - standards, size, quality and speed - has itself produced new dimensions of complexity and costs not readily apparent to those outside - or even inside - the system. There is a real danger that the system will collapse of its own weight growth at this pace cannot continue forever. 

This method assumes that the differences between the primary and secondary instruments follow a simple linear relationship. In fact, the differences may be much more complex, in which case more-advanced methods like piecewise direct standardization (PDS) may be more useful. 

The goal of methods that standardize instrument response is to find a function that maps the response of the secondary instrument to match the response of the primary instrument. This concept is used in the statistical analysis procedure known as Procrustes analysis [97], One such method for standardizing instrument response is the piecewise direct standardization (PDS) method, first described in 1991 [98,100], PDS was designed to compensate for mismatches between spectroscopic instruments due to small differences in optical alignment, gratings, light sources, detectors, etc. The method has been demonstrated to work well in many NIR assays where PCR or PLS calibration models are used with a small number of factors. 

Intermittent discharges Dangerous Substances Directive standards (UK)... 

Calcium-41 Ca-41 is produced by neutron activation of natural Ca-40. It has been found to exceed the GQ by a factor of 2 in both graphite fuel struts and desiccant from HNA (3 streams). The reported desiccant value is an upper limit probably based on trace contamination by graphite dust. In decommissioning wastes, activation of the concrete bioshield would also be expected to produce Ca-41 but these wastes streams are regarded as low level wastes in the NIREX inventory and hence GQ values do not apply. Measurements of Ca-41 can be obtained after chemical separation of Ca, which is done routinely for Ca-45 measurements. After any Ca-45 (t 14 =163 days) has decayed away, it can be measured by liquid scintillation counting. Procurement of direct standards from NPL would be required. In fresh samples, if the Ca-45 has been measured, then the Ca-41 could be estimated by comparison of activation... 

These studies also revealed the difficulty in transfer of training sets between different NMR instruments without some type of standardization to minimize spectral variation. In many instances large data sets may be compiled from individual NMR experiments run over several months (if not years), as well as data collected on different instruments and from different groups. There is no guarantee that the performance of an NMR instrument over time, or different NMR instruments, are equivalent. Gislason and co-workers have recently reported a study on the protocol for transferring PLS methods between low field process NMR spectrometers in which they found that a piece-wise direct standardization methods for accurate model transfer. This study appears to be one of the few concerning instrumental transfer of chemometric models in NMR. The development of efficient methods that allow for accurate transfer and combination of NMR spectral data from a variety of sources is an important area for future research. 

Internal standard External standard Calibration method Number of calibration standards Finear range of calibration direct/standard additions... 

The contamination of the Danube river, with pesticides in particular, is in excess of the criteria of 0.1 pg 1 for individual pesticides — the EC drinking wato- directive standard — in a number of areas. This is a matter of great concern for the population s long-term health. 

FIGURE 16.6 (a) Vertical variation of the lateral wind direction standard deviation, gq as a function of stability, (b) Vertical variation of the vertical wind direction standard deviation as a function of stability (Slade, 1968). 

This Handbook consists of two volumes. Voliune 1 contains the core material, including a discussion of the elements of a quality chemical program and information on applicable DOE, Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA) directives, standards, and requirements. The appendices to Volume 1 contain sample lines of inquiry, which may be used for ISM verification lessons learned to allow readers an opportunity to learn from the experiences of their peers and a listing of program resources. 

Application of Council Directives Standards to Which Conformity Is Declared 73/23fEEC and 89/33< /EEC... 

In the direct standard calibration method, narrowly distributed standards of the same polymer being analyzed are used. The retention volume at the peak maximum of each standard is equated with its stated molecular weight. This is the simplest method, but it is generally restricted in its utility owing to the lack of availability of many different polymer standard types. It also requires a sufficient number of standards of different molecular weights to cover completely the entire dynamic range of the column set or, at least, the range of molecular... 

Nervous system In an analysis of mortality data in Taiwan from 1971 to 2005 in two areas where exposure to arsenic in drinking water is high, the direct standardized mortality rate for cerebrovascular disease fell from 2.46/1000 person-years in 1971 to 0.63/1000 person-years in 2005 women had significantly lower mortality than men (SMR = 0.80) [27 ]. The mortality rates in populations with chronic arsenic exposure were significantly higher than in the reference populations (SMR = 1.06-1.09 in men and 1.12-1.14 in women). Although mortality fell between 1971 and 2005, chronic arsenic exposure from drinking water was associated with increased risks of cerebrovascular disease. 

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