Why Measure

The world spent an estimated US 3.1 billion on chemical measurements for medical diagnosis in 1998, most of this measurement being done in the United States and the European Union. These measurements were carried out to discover something about the patients. 

---

The first step in the addition of an electrophile such as HBr to an alkyne involves protonation and subsequent formation of an intermediate vinyl cation. Where does propyne protonate Compare energies of 1-methylvinyl and 2-methylvinyl cations. Which is more stable Why Measure CC bond distance in the more stable cation. Does the cation incorporate a full triple bond (as in propyne) or a double bond (as in propene). Examine atomic charges and electrostatic potential maps to locate the positive charge in the two cations. Is the more stable ion the one in which the charge is better delocalized Use the charges together with information about the ions geometry to draw Lewis structures (or a series of Lewis structures) for 1-methylvinyl and 2-methylvinyl cations. 

It should be mentioned that the predicted curve at highest benzene level in Figure 13 agrees with classical kinetics (no diffusion-control). It is not clear therefore why measured data at even higher benzene concentrations do not agree with classical kinetics. There may be some subtle chemical interactions at these high solvent levels. Duerksen(lT) fomd similar effects with styrene polymerization in benzene and had to correct kp for solvent. 

To appreciate why measurement results are not complete without an estimate of the measurement uncertainty. 

In the first section of my talk I hope to show why measurement of these effects as a function of regulatory actions under TSCA is not practical. If such effects are not measurable, then for regulatory purposes they must be estimated, usually by extrapolation from animal experiments. I will briefly indicate that quantitative extrapolation is an uncertain business. In the second section, I will summarize TSCA s probable impact on health, methodological difficulties in measurement notwithstanding. I will conclude with some remarks about recent regulatory pronouncements which seem to indicate that if past policies have had little discernible health impact, future ones may have even less. 

We are now in a position to see why measurement at zero current is important the emf that is measured for a cell will be incorrect if V from equation (2.3) is other than zero. In fact, we can say ... 

Numerous tests exist for determining ignition temperature, but few of them give the same result. Results may vary as much as 100° depending on the method used, on the rate of heating, on the size of the sample used, on the state of division etc. See Thermal Explosions for a discussion of why measurement variables affect ignition temp results... 

Among the antimicrobial residues giving rise to such technological problems in the manufacture of dairy products, residues of penicillin G in particular have been determined as most important. This is the reason why measures to reduce the presence of penicillin G residues in milk were originally taken to prevent economic loss and not due to public health concerns. 

Although the value of the term L often can be determined, the value of the term Xkd[Q] usually cannot, which is why measured values of [Ox]avg are used in simple second order kinetic relations for estimating the rate of oxidation by each oxidant, and by the sum of the oxidants as Equations (18) through (22) show. 

The FSTR ( Freshwater Salinity Toxicity Relationship ) model (Mount et al., 1997) was also applied with selected Daphnia magna samples. The results indicated that for most samples, the model accurately predicted toxicity. Percent differences between measured and predicted TUs were generally less than or equal to 20%. In several cases the model either over- or under-estimated toxicity. Its failure to consistently predict mortality was supported by Mount et al. (1997), who observed that in its preliminary application in field-collected samples, the Daphnia magna model tended to over-predict toxicity. Alternatively, the presence of Cu could also explain why measured toxicity was occasionally higher than the predicted toxicity. 

Table 2 demonstrates that the concentration and diffusion coefficient of dioxygen in the recast film are quite different than those in the bulk ionomer, both parameters showing values which fall between aqueous solution and bulk ionomer levels. Table 2 shows why measurements of ORR kinetics should preferably be performed at model Pt/recast ionomer interfaces in order to evaluate the ORR process in fuel cell cathodes which employ recast films of the ionomer. Gottesfeld et al. interpreted the ORR results shown in Table 1 in light of the parameters shown in Table 2, suggesting... 

There is another reason why measuring the response close to the interesting event is beneficial, viz. that any unnecessary manipulation will increase the experimental error, thus lowering the probability of detecting influences of the experimental variables on the response. 

After building the model, it is necessary to test its performance and validate it with independent measurement data. Basically, there are two reasons why measured data might be out of line with model predictions measurement or sampling errors and model failure. If sampling and measurement errors can be excluded, the model needs adjustment and modification. An adequate model is seldom obtained at the first attempt. In general, an iterative procedure is needed, where improvements are continuously made until an adequate model is achieved and measurement results are within the confidence limits of the model. 

A disease may have many symptoms and a treatment may have many effects. A particular disease may affect individuals differently and so may a given treatment. We do not study all individuals to whom we may eventually apply the treatment but a rather unrepresentative subset who form the patients in our clinical trial. We should like to be able to use the experience gained with these patients to say something about future patients. Measuring to the best extent that we are able what a particular treatment does is not the same as measuring how well it does what we should like it to do. Furthermore, certain standard statistical tools require measurements of a particular form. All of these are reasons why the measurement of effects in a clinical trial is not necessarily a simple matter. They are also reasons why measurement is not just the concern of the physician but also the concern of the statistician. 

Numerical evaluation of Eq. (6.86) reveals why measurements of the osmotic pressure 77 are more sensitive than measurements of the elevation of the boiling point. 

Why measure customer satisfaction Collecting this type of information, and understanding customers needs and desires, can help drive continuous improvement. 

Roscoe, A H. (1992). Assessing pilot workload. Why measure heart rate, HRV and respiration Biological Psychology, 34, 259 287. 

A. Why Measure Fast Interfacial Electron Transfer Rate Constants And How 103... 

Behn RD (2003) Why measure ptaformanee Difftaent purposes require different measures. PubUc Adm Rev 63(5) 586-606... 

This is why measurements are usually taken in the limiting current region where E E°. In this region = Fj . 

Humidity scans from 1 to 90 %RH at temperatures from 30°C to 80°C were generated by a computer-controlled humidifier (Tecnequip Enterprises Pty. Ltd.). The humid air was achieved by mixing dry and fully saturated air streams heated to the chosen temperature. Humidity ramps of 1 or 0.1%RH/minute were used, with an airflow of 1.4 1/min. The rate of the ramps did not affect the position or shape of the main transition of the material. However, a softening at low relative humidity was affected why measurements at the rate of 0.1%RH/minute were used in this case. A schematic view of the testing system is shown in Figure 1. 

A US manufacturer of precise non-contact product and process measurement systems, Bytewise Measurement Systems, has introduced a dedicated tyre sidewall bulge/ dent inspection system. Full details are given under the headings why measure tyre sidewalls , principle of operation, benefits of laser measurement technology, letter elimination software, and summary. 

Explain why measurement of colligative properties yields the number average molar mass. 

---