Basic operations weighing

The instrumentation developed employs units for (1) automation of the basic operations (2) sample transport (3) central control (4) the entry and weighing station and (5) the output for results and logistics. 

Each of these steps involves a certain number of basic operations, such as weighings, dilutions and volume readings. 

Knowledge of statistics (Chapter 26) is basic to effective handling of the last unit operation, evaluation of data. Many chemists rarely go beyond a calculation of the standard deviation for a set of determinations and have the erroneous notion that the use of more advanced statistical methods is restricted to enormous bodies of data. A point often overlooked is that a relatively small number of systematically planned observations may yield more information than a larger number of repeated identical observations. For example, in the simple matter of running triplicate analyses of a sample, it may be best to weigh three samples of substantially different sizes. The results obtained may reveal determinate errors that would be unsuspected with samples of equal size. 

Basic Eco-Efficiency Metrics. The above eco-efficiency categories can be captured by a small number of metrics. For illustration, let us consider the set of basic metrics adopted by BRIDGES to Sustainability (Schwarz et al., 2000, 2002), shown in Table 6.2. Informed by the work of NRTEE (1999) and WBCSD (Verfaillie and Bidwell, 2000), the metrics were chosen as ratios. Impacts are placed in the numerators and a measure of output is in the denominator. The denominator can be mass or other unit of product, functional unit, sales revenue, monetary value-added, or a certain measure of societal benefits. Expressing the metrics as ratios allow them to be compared and used in weighing decision alternatives and comparing operational units. Defined in this manner, the lower metrics are better as they reflect lower impacts per unit of value generation. 

In day-to-day practice, clinicians must weigh the risk/benefit ratio for each medication they prescribe to patients. Given their widespread usage peri-operatively as well as non-peri-operatively, a basic understanding of NSAIDs, COX-2 inhibitors, and acetaminophen is certainly imperative. The following chapters provide an overview of key points regarding specific agents within these classes, such as their recommended doses. 

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