Some Useful Testing Standards

The chapters are arranged in order of volume of usage, and wherever possible standard specifications are presented. In addition, some useful testing standards are quoted in an appendix. This book will serve as a ready reference for those readers who are involved in the construction industry such as civil engineers, consultants, chemists and technical service personnel. 

After the determination of the best-fit parameter values, the validity of the selected model should be tested does this model describe the available data properly or are there still indications that a part of the data is not explained by the model, indicating remaining model errors We need the means to assess whether or not the model is appropriate, that is, we need to test the goodness-af-fit against some useful statistical standard. 

In this stage of the investigation, poly(methyl methacrylates) (PMMAs) were selected as the polymeric probes of intermediate polarity. Polymers of medium broad molar mass distribution and of low tacticity (14) were a gift of Dr. W. Wunderlich of Rohm Co., Darmstadt, Germany. Their molar masses ranged from 1.6 X 10" to 6.13 X 10 g-mol. For some comparative tests, narrow polystyrene standards from Pressure Co. (Pittsburgh, PA) were used. 

Phosphate selection was based on the relative cost of anhydrous or crystalline grades and the amount of natural alkalinity present in the BW. The quantity of phosphate required could be determined by calculating the hardness present using a standard soap solution test (a test in widespread use in the 1970s and still employed today in some countries). 

Empirical tests are chosen by end-users because they have been shown to produce useful information. Some empirical tests have been elevated to the status of standard tests. Others remain in use by their inventors. 

A comparison of the imprecision of two methods may assist in the choice of one for routine use. Statistical comparison of values for the standard deviation using the F test (Procedure 1.2) may be used to compare not only different methods but also the results from different analysts or laboratories. Some caution has to be exercised in the interpretation of statistical data and particularly in such tests of significance. Although some statistical tests are outlined in this book, anyone intending to use them is strongly recommended to read an appropriate text on the subject. 

In most kinetic investigations, one assumes the enzyme remains stable over the course of the measurement. When this is the case, corrective measures must be taken to obtain valid kinetic data. A useful test for any enzyme system is to plot enzyme activity versus time. This is readily accomplished by using a standardized assay (usually at optimal or saturating substrate concentrations) to measure the enzyme s specific activity periodically during the course of some experiment. This approach may fail to detect a reduction in activity characterized by lower affinity for substrate however, use of a subsaturating substrate concentration in a time-course study will reveal this behavior. 

To help in law enforcement, a federal law was enacted in 1994 that established a Federal Bureau of Investigation (FBI) national DNA database called CODIS (Combined DNA Index System). By 1998, all 50 states had passed laws that require aU persons convicted of serious sex offenses and other crimes to provide a sample of blood for DNA analysis. The marker results are entered into the CODIS database, along with the results of crime scene samples. The methods and panel of markers used are standardized for all states so that results from a sample tested in one state can be compared with all the files in the database. Some groups argue that requiring a blood sample is a... 

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