A weighting scale

A weighting scale, dBA The unit of sound intensity expressed as a logarithmic scale, related to a reference level of 10 W m"-. The A weighting scale is the most commonly used scale, as it reduces the response of sound meters to very high and low frequencies and emphasize those within the range audible by the human ear. 

Although pharmacists can receive objective patient data from local laboratories or from physicians, it may be decided that it is more convenient for the patient and pharmacist if a laboratory monitoring/screening service is performed at the point of care. Several types of monitors and equipment can be purchased by pharmacists and integrated into their practices. For example, pharmacists who implement a wellness program may purchase a body-fat analyzer, a weight scale, or a monitor that measures the lipid and glucose levels of... 

Human loudness perception depends in a complex manner on both frequency and the overall loudness of sound. (For example, bass is more difficult to hear in music played at low volume than in the same music played at high volume.) To capture this behavior, two weighting scales have been developed for use in sound hazard analysis. The most common of these is the A weighting scale, which is commonly used to assess occupational and environmental noise. The A scale weights sounds in the 1000-6000 Hz range much more heavily than low-frequency sounds. The A-weighted intensities (dBA) of some common sounds are listed in Table 5. By contrast, the C weighting scale is used for very loud sounds and is a much flatter function of frequency. 

One other distinction needs to be made between random X and X with random measurement error. Neither implies that X is biased. Bias implies a constant effect across all measurements. For example, if a weight scale is not calibrated properly and when no one is standing on it, the scale records a measure of 1 kg, then when any person is measured the weight will be biased high by 1 kg. This is not the type of measurement error that is being discussed here because any constant bias in a measuring instrument will be reflected in the... 

What is the significance of the A weighting scale when measuring sound ... 

If the descriptors are on different scales then those which naturally occupy a larger scale may be given more weight in the subsequent analysis, simply because of their natura units. In autoscaling the descriptors are scaled to zero mean and a standard deviatior of 1. 

P or preparations on a larger scale, a stoneware vessel may be conveniently employed and the lowering of temperature achieved by the addition of a quantity of crushed ice equal in weight to that of the hydrochloric acid and water. The mixture should be stirred mechanically. 

Dimerization in concentrated sulfuric acid occurs mainly with those alkenes that form tertiary carbocations In some cases reaction conditions can be developed that favor the formation of higher molecular weight polymers Because these reactions proceed by way of carbocation intermediates the process is referred to as cationic polymerization We made special mention m Section 5 1 of the enormous volume of ethylene and propene production in the petrochemical industry The accompanying box summarizes the principal uses of these alkenes Most of the ethylene is converted to polyethylene, a high molecular weight polymer of ethylene Polyethylene cannot be prepared by cationic polymerization but is the simplest example of a polymer that is produced on a large scale by free radical polymerization... 

An example of a size-exclusion chromatogram is given in Figure 7 for both a bench-scale (23.5 mL column) separation and a large-scale (86,000 mL column) mn. The stationary phase is Sepharose CL-6B, a cross-linked agarose with a nominal molecular weight range of 5000-2 x 10 (see Fig. 6) (31). 

The polymeric products can be made to vary widely in physical properties through controlled variation in the ratios of monomers employed in thek preparation, cross-linking, and control of molecular weight. They share common quaHties of high resistance to chemical and environmental attack, excellent clarity, and attractive strength properties (see Acrylic ester polymers). In addition to acryHc acid itself, methyl, ethyl, butyl, isobutyl, and 2-ethylhexyl acrylates are manufactured on a large scale and are available in better than 98—99% purity (4). They usually contain 10—200 ppm of hydroquinone monomethyl ether as polymerization inhibitor. 

Quality Specifications. Because of the extreme sensitivity of polyamide synthesis to impurities ia the iagredients (eg, for molecular-weight control, dye receptivity), adipic acid is one of the purest materials produced on a large scale. In addition to food-additive and polyamide specifications, other special requirements arise from the variety of other appHcations. Table 8 summarizes the more important specifications. Typical impurities iaclude monobasic acids arising from the air oxidation step ia synthesis, and lower dibasic acids and nitrogenous materials from the nitric acid oxidation step. Trace metals, water, color, and oils round out the usual specification Hsts. 

Comparing two or more complex alternatives is more difficult than examining equipment capacity or first cost. Characteristics of alternatives should be weighted for relative importance and measured on a common scale to aEow proper evaluation. Many characteristics such as first cost, capacity, space requirement, and annual energy use can be measured objectively and used for system comparisons. Experience has shown that items such as maintenance expense, component life, and downtime can also be rehably estimated. Other factors, eg, system maintainabEity, flexibEity, and comfort, are more arbitrary. 

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