Effect Relationships

Both contamination and pollution entail the perturbation of the natural state of the environment by anthropogenic activity. The two terms are distinguishable by the severity of the effect pollution induces the loss of potential resources. Additionally, a clear cause-effect relationship must be established for a substance to be classified as a pollutant towards a particular organism. 

That some enhancement of local temperature is required for explosive initiation on the time scale of shock-wave compression is obvious. Micromechanical considerations are important in establishing detailed cause-effect relationships. Johnson [51] gives an analysis of how thermal conduction and pressure variation also contribute to thermal explosion times. 

Air quality criteria are cause-effect relationships, observed experimentally, epidemiologically, or in the field, of exposure fo various ambient levels of specific pollutants. The relationships between adverse responses to air pollution and the air quality levels at which they occur have been discussed in Chapter 4 and illustrated in Table 4-5 and Fig. 4-10. 

KDC has a cause and effect relationship between as the primary cause leading to secondary failures. Besides its drastic operational effects on redundant systems, the numerical etlects that reduce sy.stem reliability are pronounced Equation 2.4-5 shows that the probability ut failing a redundant. system composed of n components is the component probability raised to the n-th power. If a common clement couples the subsystems. Equation 2.4-5 is not correct and the failure rate is the failure rate of the common element. KDC is very serious because the time from primary failure to secondary failures may be too short to mitigate. The PSA Procedures Guide (NUREG,/CR-2.3(X)) cl.issities this type as "Type 2."... 

A toxic reaction may take place during or soon after exposure, or it may only appear after a latency period. Chronic toxicity requires exposure of several years for a toxic effect to occur in humans. With respect to experimental animals, the animals are usually exposed for most or all of their life time to ascertain the occurrence of chronic toxicity. Acute toxic reactions that occur immediately are easy to associate with the exposure and the exposure-effect relationship can readily be demonstrated. The longer the time interval between exposure and effect, the more difficult it is to delineate the relationship between exposure and effect. 

Ultimately physical theories should be expressed in quantitative terms for testing and use, but because of the eomplexity of liquid systems this can only be accomplished by making severe approximations. For example, it is often neeessary to treat the solvent as a continuous homogeneous medium eharaeterized by bulk properties such as dielectric constant and density, whereas we know that the solvent is a molecular assemblage with short-range structure. This is the basis of the current inability of physical theories to account satisfactorily for the full scope of solvent effects on rates, although they certainly can provide valuable insights and they undoubtedly capture some of the essential features and even cause-effect relationships in solution kinetics. Section 8.3 discusses physical theories in more detail. 

The essential weakness of the correlation approach is that it lacks a linkage to molecular events. A correlation is not a cause-effect relationship. Nevertheless, with sufficient weight of evidence it becomes reasonable to seek an underlying... 

It is important to keep in mind that statistically based studies by themselves can never prove the e.xistence of a cause and effect relationship. However, such obseix ations may be used to generate or to test a hypothesis. Many possibilities exist for introducing bias in this type of investigation, and statistical correlations may be fortuitous. 

The ANN was able to assimilate the cause-effect relationship of the density of the ester, its structure and temperature. The training and testing results are shown in Fig. 10-14 for individual ester series. The network with the proposed training routine converged in less than 100 iterations for all the esters. 

In this approach, connectivity indices were used as the principle descriptor of the topology of the repeat unit of a polymer. The connectivity indices of various polymers were first correlated directly with the experimental data for six different physical properties. The six properties were Van der Waals volume (Vw), molar volume (V), heat capacity (Cp), solubility parameter (5), glass transition temperature Tfj, and cohesive energies ( coh) for the 45 different polymers. Available data were used to establish the dependence of these properties on the topological indices. All the experimental data for these properties were trained simultaneously in the proposed neural network model in order to develop an overall cause-effect relationship for all six properties. 

The distinction between machine conditions and fabricating variables is a necessary one to avoid mistakes in using problem-and-solution or cause-and-effect relationships to advantage. If the processing variables are properly defined and measured, not necessarily the machine settings, they can be directly... 

As a preamble to looking at some of these specific problems, it is worth reiterating effective control strategies are achieved through the planned avoidance of problems and understanding cause-and-effect relationships. 

With regard to cause-and-effect relationships, in practice, a problem originating from a single-source cause may have a lead-on effect that gives rise to multiple localized problems or becomes evident in several different areas of the boiler plant. Conversely, what appears to be a single localized problem may in fact be the combined effect of a number of smaller separate causes. 

A wide range of cause-and-effect relationship alternatives may arise, depending on the particular circumstances, especially in smaller residential and commercial properties. But combinations of poor system design,... 

Selected graphs in the text are available in interactive form. Students can manipulate parameters and see cause-and-effect relationships. 

The uncertainties associated with the data base of an individual river basin are compounded when the intent is to provide a global perspective. This point is made in a recent bound volume of UNEP data in which a number of data interpretation limitations are sited. Quality of data varies from one individual reporting entity to another and the precision of the data is usually not possible to ascertain. Thus direct comparisons between data from one country, or even one laboratory to the next are not always possible. Since uncertainties associated with the data (variability, accuracy, precision, etc.) are often not specified, the significance of the data may be difficult to determine and no valid interpretation of the data may therefore be possible. It comes as no surprise that these and similar data from other data bases are often, if not usually, inadequate to establish cause and effect relationships. 

Mechanistic Approaches. Adequate and appropriate river-quality assessment must provide predictive information on the possible consequences of water and land development. This requires an understanding of the relevant cause and effect relationships and suitable data to develop predictive models for basin management. This understanding may be achieved through qualitative, semi-quantitative or quantitative approaches. When quantitative or semi-quantitative methods are not available the qualitative approach must be applied. Qualitative assessments involve knowledge of how basin activities may affect river quality. This requires the use of various descriptive methods. An example of this kind of assessment is laboratory evaluation of the extent to which increases in plant nutrients, temperature or flow may lead to accelerated eutrophication with consequent reduction of water quality. 

Cause and effect relationships associated with erosion and river quality can be clearly established for many activities. For example construction activity at a site could be clearly responsible for a resulting landslide into a river. But other activities such as those related to agriculture and forestry may not be so apparent. Spatial and temporal linkages may not be so clearly established. 

What is needed is an alternative approach which permits development of valid cause and effect relationships. This strategy, one involving intensive surveys, is referred to here as mechanistic. The Willamette River, Oregon, USA, is used as a case study to illustrate quantitative, semi-quantitative and qualitative approaches to mechanistic assessment of river water quality using, respectively, dissolved oxygen depletion, erosion/deposition and potentially toxic trace elements as examples. 

In evaluating the influence of individual climate controls, we have three major concerns the time frame over which the control operates, the potential magnitude of the control s influence on climate, and whether a strong correlation between some forcing phenomenon and climatic response actually indicates a cause-effect relationship. 

These measures are vital steps towards helping participants to feel less isolated, to develop further, and to create highly effective relationships. 

The easiness of the DSS to explore the problem at hand, to derive possible solutions, and discover and analyse the cause-effect relationships... 

Simulation is best described as the process of translating a real system into a working model in order to run experiments. A simulation does not duplicate a system rather it is an abstraction of reality using mathematics to express cause-and-effect relationships that determine the behavior of the system. Hence the representation displayed on a computer may not always be pictori-ally similar to the real system, and, if it is, then it must be regarded as an added bonus. Software for computer simulation is often customized and based on that developed in academia. There are not many commercial packages available for pharmaceutical formulation. 

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