Stress unpredictable

The condition of the test metal is important. Clean metal samples with uniform finishes are preferred. The accelerating effects of surface defects lead to deceptive results in samples. The ratio of the area of a defect to the total surface area of the metal is much higlier in a sample than in any metal in service. This is an indication of the inaccuracy of tests made on metals with improper finishes. The sample metal should have the same type of heat treatment as the metal to be used in service. Different heat treatments have different effects on corrosion. Heat treatment may improve or reduce the corrosion resistance of a metal in an unpredictable manner. For the purpose of selectivity, a metal stress corrosion test may be performed. General trends of the performance of a material can be obtained from such tests however, it is difficult to reproduce the stress that actually will occur during service. 

Yield Stress The effect of hydrogen on the yield stress of iron and steels is unpredictable. For very pure iron single crystals and polycrystals the yield stress is frequently found to be decreased by hydrogen, but it may increase or stay the same, depending on the dislocation structure, crystal orientation and purity of the iron . Little information is available for steels. 

Jones, H.G. (1980). Interaction and integration of adaptive responses to water stress the implications of an unpredictable environment. In Adaptation of Plants to Water and High Temperature Stress, ed. N.C. Turner and P.J. Kramer, pp. 353-65. New York Wiley. 

This behavioural syndrome, rather emotively called learned helplessness", is widely believed to share many features of depression, not least because both culminate in psychomotor retardation and both are linked with experience of uncontrollable, unpredictable stress. Whether or not learned helplessness really is an analogue of depression remains controversial (Maier 1993). Nevertheless, escape deficits in rats are prevented by pretreatment with antidepressants from different generic groups. Other psychotropic agents, such as CNS stimulants and neuroleptics, are generally ineffective. 

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. 

Haile, C.N., GrandPre, T., Kosten, T.A. Chronic unpredictable stress, but not chronic predictable stress, enhances the sensitivity to the behavioral effects of cocaine in rats. Psychopharmacology. 154 213, 2001. 

Panic disorder is characterized by the occurrence of panic attacks that occur spontaneously and lead to persistent worry about subsequent attacks and/or behavioral changes intended to minimize the likelihood of further attacks. Sporadic panic attacks are not limited, however, to those with syndromal panic disorder as they do occur occasionally in normal individuals and in those with other syndromal psychiatric disorders. The hallmark of panic disorder is that the panic attacks occur without warning in an unpredictable variety of settings, whereas panic attacks associated with other disorders typically occur in response to a predictable stimulus. For example, a person with acrophobia might experience a panic attack when on a glass elevator. A patient with obsessive-compulsive disorder (OCD) with contamination fears may have a panic attack when confronted with the sight of refuse, and a combat veteran with post-traumatic stress disorder (PTSD) may experience a panic attack when a helicopter flies overhead or an automobile backfires. 

Having shown that both Sprengel explosives and organic peroxides have been seriously studied, and in numerous cases applied as commercial energetic materials, their current status needs to be addressed. As stressed in each case, these materials were too unstable, unfriendly, and unpredictable for continued use in a field populated with much better alternatives. Terrorists, however, often do not have ready access to the commercial and military alternatives in use today. They are not deterred by the factors that forced the Sprengel explosives and the peroxides into mainstream obscurity. 

According to prevailing concepts, stress is being experienced when an individual is confronted with a situation that is appraised as personally threatening and for which adequate coping resources are unavailable (Lazarus, 1985). Biological stress reactions are particularly elicited during novel, uncertain, and unpredictable situations (Mason, 1968). These concepts emphasize that individual perception and behavioral adaptations to an event are critical to the experience of stress. In addition, physical stimuli, such as injury. 

Studies on the noradrenergic axis in nonhuman primates provide evidence that early environmental stressors may provoke biological and behavioral phenocopies of human clinical anxiety states. We have used the primate model of developmental psychopathology pioneered by Rosenblum et al. (1991) to explore this issue. Nonhuman primates who were reared as infants by mothers undergoing environmental stress induced by unpredictable or variable foraging demand (VFD-reared) conditions were compared with nonhuman primates reared as infants by mothers exposed to predictable (either low [LFD-reared] or high [HFD-reared]) foraging demand conditions. 

Consistent with earlier studies, Muscat et al. ( 58) reported on chronic exposure to mild unpredictable stress in rats as a model to study the antidepressant-reversible decreases in the consumption of palatable sweets. Using this model, they found that certain dopamine agonists (i.e., quinpirole, bromocriptine) administered intermittently had the same positive effects as TCAs. They further postulated that the infrequent, intermittent administration of dopamine agonists (e.g., psychostimulants) may avoid problems with tolerance and abuse while providing a clinically relevant antidepressant strategy. A report by Kapur and Mann ( 59) comprehensively reviews the role of dopamine in depressive disorders. They discuss several lines of evidence, including the following ... 

Many of these parameters are quite predictable, especially when applying some of the thermodynamic concepts described earlier. The increased processing time, which brings with it increased exposure to stressful conditions (both mechanical and as a result of environmental conditions used in the process, especially when that process is aqueous based) is much more unpredictable, and is often the root cause of much angst during the preparation of early commercial batches. 

Malo-Lacttc Starter Culture. This must be monitored with great care and precision. Most California wineries don t use Leuconostoc starter cultures for malo-lactic fermentations because the organisms are generally so unpredictable and difficult to control. Where used, in the cooler coastal areas, the results are worth the effort, but it must be stressed that this is not for amateurs. Precise control is absolutely essential. See Pilone and Kunkee (10), Tchelistcheff et al. (II), and earlier papers by Kunkee. 

Chronic mild stress (CMS) presents mice with an unpredictable barrage of stressors to induce (rather than simply measure) a depressed state. CMS reduces sucrose or saccharin intake in mice, a symptom of anhedonia (see above). CMS may also be responsible for decreases in sexual and aggressive... 

I., Lesch, K. P., et al. (2008) Animal models of depression in dopamine, serotonin, and norepinephrine transporter knockout mice prominent effects of dopamine transporter deletions. Behav Pharmacol 19, 566-574. Luo, D. D., An, S. C. and Xhang, X. (2008) Involvement of hippocampal serotonin and neuropeptide Y in depression induced by chronic unpredicted mild stress. Brain Res Bull 77, 8-12. 

Yalcin, I., Aksu, F., Bodard, S., Chalon, S. and Belzung, C. (2007) Antidepressantlike effect of tramadol in the unpredictable chronic mild stress procedure possible involvement of the noradrenergic system. Behav Pharmacol 18, 623-631. 

Pothion, S., Bizot, J. C., Trovero, K and Belzung, C. (2004) Strain differences in sucrose preference and in the consequences of unpredictable chronic mild stress. Rehav Brain Res 155, 135-146. 

Mineur, Y. S., Prasol, D. J., Belzung, C. and Crusio, W. E. (2003) Agonistic behavior and unpredictable chronic mild stress in mice. Behav Genet 33, 513-519. 

Papp M, Willner P, Muscat R (1991) An animal model of anhedonia attenuation of sucrose consumption and place preference conditioning by chronic unpredictable mild stress. Psychopharmacology 704 255-259. 

---