Swiss cheese effect

Figure 24. Swiss Cheese effect in GMC negative resist produced by shock rinsing after development.

Usually, an accident is caused not by a single event but by the occurrence of several concurrent events, sometimes called Swiss cheese effect, in which corrosion phenomena occur at the microscopic and macroscopic levels and cause strong deterioration of material properties, leading to the failure of a structure. In such situations, the solution to a problem can be the identification of a corrosion barrier that hinders the concatenation of events that would lead to failure. 

FIGURE 16.10 Distance from trace to copper plane.(The copper planes do not take into account the swiss-cheese effect from vias.The planes are assumed to be continuous solid planes.)... 

Bacteria from the genera Lactobacillus and Streptococcus are involved in the first steps of dairy production (3). The raw materials produced by their effects usually only acquire their final properties after additional fermentation processes. For example, the characteristic taste of Swiss cheese develops during a subsequent propionic acid fermentation. In this process, bacteria from the genus Propionibacterium convert pyruvate to propionate in a complex series of reactions (2). 

Chen, G., Kocaoglu-Vurma, N. A., Harper, W. J., and Rodriguez-Saona, L. E. (2009). Application of infrared microspectroscopy and multivariate analysis for monitoring the effect of adjunct cultures during Swiss cheese ripening. J. Dairy Sci. 92,3575-3584. 

The effective management of medical equipment-related risk requires a meaningful and practical framework or paradigm from which to start. As described here. Reason s modified Swiss cheese model provides one such paradigm. Metaphorically and conceptually, the model also tends to be readily understood, which further aids in its acceptance as a risk management tool. 

Table 2.1 shows examples of how the elements of an accident fit together. Reading the table from left to right, you can see how an accident evolves. First, there is a hazardous condition—such as large quantities of flammable liquids. Then the initiating event occurs—for example, a valve sticks open. The effect of a valve-failed-open propagates a pressure rise in the system. Now, an in-line relief valve can mitigate the effects of the initial event. If not, an accident ensues—explosion. Chapter 11 discusses and details the events that lead to an accident. It also discusses James Reason s famous Swiss cheese accident model. 

Propionic acid is an active microbicide in the undissociated form only in consequence it exhibits optimum efficacy at pH values below 5. Propionic acid is primarily effective against moulds. The activity against yeasts is minimal and the activity against bacteria is poor. Microbes belonging to the genus Propionibac-terium produce propionic acid during fermentation of Swiss Gruy re cheese. However, Bacterium mesentericus is an exception as it is very sensitive to the effect of propionic acid. 

The growth, acid production and lactate utilization by propionibacteria (especially P. freudenreichii and P. shermanii) are inhibited by long-chain fatty acids (10-100 mg/1 each) lauric (C o), myristic (C o), oleic (Cis i) and linoleic (Ci8 2) acids (Boyaval et al, 1995), present in milk lipids. However, the inhibitory effects of these acids were only observed in lactate-yeast extract medium (YEL), but not in milk or curd. The work was undertaken in connection with the often poor eyes formation in Swiss-type cheese. 

---