Hard aspects defined

Voluntary Aspects. People voluntarily accept some risks, such as driving a car, and have others imposed upon them, such as water pollution. The line between voluntary and involuntary risks is often hard to define and is frequently determined by availabilty of resources and social practices, e.g., if one has a filter, one could drink only filtered water. In general, the American public, probably reflecting our individualistic biases, is more tolerant of voluntary risks (8). Americans do not readily accept their government to be the arbiter of personal risk, demonstrated by the brouhaha that developed over governmental attempts to mandate use of seat belts and motorcycle helmets (9). (For a good discussion of the broader concept of risk and consent, see 10). Much more acceptable appears to be government efforts to protect the public from imposed risks. 

As a rational compromise, the comparison of modeling results with experiments may be considered as the way to select between alternative descriptions if other criteria cannot be applied. Otherwise it is hard to define the ambit beyond which an optimization of parameters for a limited set of important stages transforms into the total adjustment of the kinetic scheme to some particular experiment. This aspect will be further discussed in Section II.C. 

The topic of hair and skin conditioning is complex and not easily covered by a short discussion of the polymers used to condition these surfaces. The very concept of conditioning is hard to define and describe, yet it is an important aspect to understand if one is to appreciate the benefits of conditioning polymers. Two recent reviews have attempted to summarize what it means when consumers talk about the condition of their hair and skin (152,153). It is generally accepted that conditioning describes the perceived benefits a consumer receives from a personal care product when it is applied to the hair or skin. These benefits manifest themselves in the way the hair and skin feel, look, shine, and so forth after the consumer applies a particular product. 

Risks as a result of synergy failure An important aspect of mechatronic systems risk assessment is a mutual connection of the individual components. Even a minor, hard-to-define failure of a part of the system could cause, following incorrect assessment, a shutdown of the whole system followed by accidents or injuries. Malfunction of a mechanical element that cannot be detected, for example, due to the absence or malfunction of a sensor, may also cause an accident or injury. 

It would be incomplete for any discussion of soap crystal phase properties to ignore the colloidal aspects of soap and its impact. At room temperature, the soap—water phase diagram suggests that the soap crystals should be surrounded by an isotropic Hquid phase. The colloidal properties are defined by the size, geometry, and interconnectiviness of the soap crystals. Correlations between the coUoid stmcture of the soap bar and the performance of the product are somewhat quaUtative, as there is tittle hard data presented in the literature. However, it might be anticipated that smaller crystals would lead to a softer product. Furthermore, these smaller crystals might also be expected to dissolve more readily, leading to more lather. Translucent and transparent products rely on the formation of extremely small crystals to impart optical clarity. 

These excitations are widely used to characterize electronic states and excitations, to test theories about electronic phenomena, and to delineate the nature of local sites in glasses, disordered soHds, intercalates, etc. However, this aspect of changing color with pressure is so general as to be hardly satisfactory for defining piezochromism. 

The all-important difference between the friction properties of elastomers and hard solids is its strong dependence on temperature and speed, demonstrating that these materials are not only elastic, but also have a strong viscous component. Both these aspects are important to achieve a high friction capability. The most obvious effect is that temperature and speed are related through the so-called WLF transformation. For simple systems with a well-defined glass transition temperature the transform is obeyed very accurately. Even for complex polymer blends the transform dominates the behavior deviations are quite small. 

Skeletal fluorosis can be defined as excessive deposition of fluoride in bone. This is a pathological condition that is by far the most important aspect of chronic exposure to elevated levels of fluoride, either by inhalation or by ingestion. The skeletal deformities may be associated with or accentuated by nutritional deficiencies or even malnutrition and hard manual work or, possibly, other conditions found in areas of long-term social and nutritional deprivation [6]. See, for instance Fig. 1 of [54]. The situation is specific also for populations consuming large volumes of water, such as athletes or people with certain medical conditions or... 

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