Stress factors

Perhaps the most important stress factor affecting corrosion fatigue is the frequency of the cyclic stress. Since corrosion is an essential component of the failure mechanism and since corrosion processes typically require time for the interaction between the metal and its environment, the corrosion-fatigue life of a metal depends on the frequency of the cyclic stress. Relatively low-stress frequencies permit adequate time for corrosion to occur high-stress frequencies may not allow sufficient time for the corrosion processes necessary for corrosion... 

Time dependency refers to the time available to cope with a process event. Time pressure is a well-known stress factor which affects human performance. Here, the time response of plant equipment and chemical processes will determine the time available to respond to an incident. 

The extent to which a particular combination of such "operating environment" factors will be perceived by the workers as being stressful will depend on the available resources such as the quality of the control panel, procedures, training, organizational and social factors, and, finally, the individual characteristics of the workers. The outcome of this transaction between stress factors and coping resources will influence the onset of worker stress. Situations are not stressful merely because of the presence of a number of external stressors, but because they are perceived as such by workers. 

Stress factors Sustained stress, cyclic stress, compression set (in rubbers) under continuous loading... 

Where stress factors are present in combination with high temperatures, these may result in both thermal fatigue cracking and corrosion fatigue. There are various potential stress factors, including ... 

Contemporary forest declines were initiated about 1950-1960, virtually simultaneously throughout the industrial world at the same time as damage to aquatic systems and structures became apparent. A broad array of natural and anthropogenic stresses have been identified as components of a complex web of primary causal factors that vary in time and space, interact among each other, affect various plant growth and development systems and may result in the death of trees in mountainous ecosystems. As these ecosystems decline, the alterations in forest ecology, independent of the initial causal complex, become themselves additional stress factor complexes leading to further alterations. 

When bacteria or almost any organism are exposed to high temperatures, the synthesis of a set of HSPs encoded by heat shock genes is rapidly and transiently induced this reaction has been designated as the heat shock response. Later, it was foimd that most heat shock genes are not only induced by heat, but by many other stress regimens (Table 1). The stress factors have been classified into three groups physicochemical factors, metabolically harmful substances and complex metaboHc processes. Therefore, the heat shock is often called the stress shock to comply with these observations. 

It transpires that the heat shock genes of one single bacterial species are regulated by different mechanisms. Genes and operons controlled by one particular regulator are called regulons and, if there are at least two regulons in one species induced by the same stress factor, they form a stimulon. 

Despite increased citrate accumulation in roots of Zn-deficient rice plants, root exudation of citrate was not enhanced. However, in distinct adapted rice cultivars, enhanced release of citrate could be observed in the presence of high bicarbonate concentrations in the rooting medium, a stress factor, which is frequently associated with Fe and Zn deficiency in calcareous soils (235) (Hajibo-huid, unpublished). This bicarbonate-induced citrate exudation has been related to improved Zn acquisition in bicarbonate-tolerant and Zn-efficient rice genotypes (Fig. 9) (23S). Increased exudation of sugars, amino acids, and phenolic compounds in response to Zn deficiency has been reported for various dicotyledonous and monocotyledonous plant species and seems to be related to increased... 

Aluminium toxicity is a major stress factor in many acidic soils. At soil pH levels below 5.0, intense solubilization of mononuclear A1 species strongly limits root growth by multiple cytotoxic effects mainly on root meristems (240,241). There is increasing evidence that A1 complexation with carboxylates released in apical root zones in response to elevated external Al concentration is a widespread mechanism for Al exclusion in many plant species (Fig. 10). Formation of stable Al complexes occurs with citrate, oxalate, tartarate, and—to a lesser extent— also with malate (86,242,243). The Al carboxylate complexes are less toxic than free ionic Al species (244) and are not taken up by plant roots (240). This explains the well-documented alleviatory effects on root growth in many plant species by carboxylate applications (citric, oxalic, and tartaric acids) to the culture media in presence of toxic Al concentrations (8,244,245) Citrate, malate and oxalate are the carboxylate anions reported so far to be released from Al-stressed plant roots (Fig. 10), and Al resistance of species and cultivars seems to be related to the amount of exuded carboxylates (246,247) but also to the ability to maintain the release of carboxylates over extended periods (248). In contrast to P deficiency-induced carboxylate exudation, which usually increases after several days or weeks of the stress treatment (72,113), exudation of carboxylates in response to Al toxicity is a fast reaction occurring within minutes to several hours... 

W = weight in kg, El = height in cm, A = age in years Energy expenditure then should be multiplied by a stress factor to estimate the total energy expenditure (TEE) ... 

It should be emphasised that if animals are suffering then the farmer is encouraged to use the most effective veterinary method for alleviating suffering as quickly as possible. However, attention to husbandry, nutrition and stress factors will markedly reduce the incidence of disease. 

This is determined by applying a suitable design stress factor (factor of safety) to the maximum stress that the material could be expected to withstand without failure under standard test conditions. The design stress factor allows for any uncertainty in the design methods, the loading, the quality of the materials, and the workmanship. 

For materials subject to conditions at which the creep is likely to be a consideration, the design stress is based on the creep characteristics of the material the average stress to produce rupture after 105 hours, or the average stress to produce a 1 per cent strain after 105 hours, at the design temperature. Typical design stress factors for pressure components are shown in Table 13.1. 

For many decades, the standard technique for measuring carotenoids has been high-pressure liquid chromatography (HPLC). This time consuming and expensive chemical method works well for the measurement of carotenoids in serum, but it is difficult to perform in human tissue since it requires biopsies of relatively large tissue volumes. Additionally, serum antioxidant measurements are more indicative of short-term dietary intakes of antioxidants rather than steady-state accumulations in body tissues exposed to external oxidative stress factors such as smoking and UV-light exposure. 

The theories on individual decision making from other scientific disciplines tend to stress factors such as status, social peer pressure, time availability, mood, cultural aspects, self-affirmation, altruism, and self-perception, as explanatory variables to decision making [12, 13]. These latter factors are far less favourable for economic valuation since the value would be unpredictable and varying dependent on situation. They may, however, provide an equally or even better description of decision making. 

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