Pivotal event

It has already been stressed that the discovery of superoxide as the enzymatically produced diffusion-free dioxygen radical anion [1-3] was a pivotal event in the study of free radical processes in biology. It is not of course that the McCord and Fridovich works were the first ones in free radical biology, but the previous works were more of hypothetical character, and only after the identification of superoxide by physicochemical, spectral, and biochemical analytical methods the enzymatic superoxide production became a proven fact. 

Several different changes in mitochondria occur during apoptosis. These include a change in membrane potential (usually depolarization), increased production of reactive oxygen species, potassium channel activation, calcium ion uptake, increased membrane permeability and release of cytochrome c and apoptosis inducing factor (AIF) [25]. Increased permeability of the mitochondrial membranes is a pivotal event in apoptosis and appears to result from the formation of pores in the membrane the proteins that form such permeability transition pores (PTP) may include a voltage-dependent anion channel (VDAC), the adenine nucleotide translocator, cyclophilin D, the peripheral benzodiazepine receptor, hexokinase and... 

It seems likely that the pivotal events in the evolution of a differentiated cell reflect changes in gene expression that result from a complex hierarchy of controls. The key to understanding differentiation, therefore, is to identify the regulatory factors responsible for the controls involved in differentiation and to explain how they act. 

Radicals such as CCI3, produced during the oxidation of carbon tetrachloride, may induce lipid peroxidation and subsequent destruction of lipid membranes (Figure 8.3). Because of the critical nature of various cellular membranes (nuclear, mitochondrial, lysosomal, etc.), lipid peroxidation can be a pivotal event in cellular necrosis. 

A pivotal event for the surge of interest in process control, we believe, was the publication of three insightful critiques [1-3] that analyzed the gap between academic theory and industrial practice. Bridging this gap became the goal of the new generation of process control theory. 

The following example comes from a story, in which a poor man becomes rich by eavesdropping. The poor man has overheard that a certain bush has a special medical potency. In the following excerpt, the pivotal event in the story is described. The poor man, who is unemployed, is staying at an old woman s house. He learns that the king is in a critical condition. The poor man will eventually cure the king with the leaves from the magical bush, which makes him rich. 

In some ways this was a pivotal event, because a different situation in the UK thereafter became clear it was expected of the pharmaceutical industry—and very much still is—that it would take forthright action against any doctor found beyond all shadow of doubt to have committed fraud. This has led to 23 further cases since the Siddiqui case was submitted by companies and the trade associ-... 

Oxidase activation is the pivotal event with respect to microbicidal metabolism in that its products, 02 and H, serve as reactants in a variety of disproportionation and radical reactions yielding H2O2 and highly reactive oxidizing species such as hydroxyl radical (-OH), and either singlet molecular oxygen ( O2) or an oxidant having the reactive po-... 

ETA and ETA are two distinct methods used in PRA. ETA is a technique used to display sequences of system (or human) failures or successes that can lead to specific end states and estimate the likelihoods (frequency) of each end state. ETA is often used to analyze the probability of failure or success of pivotal events in an event tree. A pivotal event is treated as top event and proceeded down to basic events using logic gates in each fault tree. Despite the fact that the two methods are widely adopted, some limitations as the lack of ability of modeling dependencies are suffered (Khakzad et al. 2011). 

Event trees are used to display sequences of events that can lead to specific end states. The headings of an ET are the Initiating Events (IE), the Pivotal Events (PEs), and the End States (ESs). An illustration of an ET is shown in Figure 3(a). 

We call the elements in the power set of an ES node General End States (GESs) and use them as the states of ES nodes in ENs. For end states of an ET are influenced by all the pivotal events, the graphic representation of ETs in a network form is clear. The graphic representation of the ET in Figure 3(a) is shown in Figure 3(b). 

Noticing from the CBMT in Table 4, the size of a CBMT also faces the problem of state explosion. With n end states and m pivotal events the size of the ET s CBMT is 3 x (2" - 1). 

The event tree is shown in Figure 4. It consists of one initiating event, three pivotal events and five end states. The initiating event is fire in one of the two tunnel tubes. 

Recognizing the richness and fullness of history, the ReferencePoint Press Understanding World History series fosters an evaluation and interpretation of history and its influence on later generations. Each volume in the series approaches its subject chronologically and topically, with specific focus on nations, periods, or pivotal events. Primary and secondary source quotations are included, along with complete source notes and suggestions for further research. 

By induction of flowering we mean all those processes that cause the cells of the shoot meristem to switch from the course of development that they have hitherto pursued and now form the leaf organs of the flower instead of leaves. Once this pivotal event has been initiated, the switches are thrown so that the processes of differentiation leading to flowers or inflorescences foWo w (Fig. 230). The induction of flowering is of particular interest to the physiologist and the plant grower. This is because differentiation follows the induction of flowering almost automatically. Control of flower... 

The light stimulus is received by the leaf but the pivotal event takes place in the shoot meristem. This finding alone suggests the existence of a flowering hormone even in plants that are dependent on day length, which migrates from the leaves to the apical meristem. Another experi-... 

See Event Tree Analysis (ETA), Initiating Event (IE), and Pivotal Event (PE) for additional related information. 

The discovery of the antibacterial activity of sulfanilamide in 1932 and that of penicillin in 1940 were pivotal events that served to establish the drug industry in its present form. An intensive research effort was initiated that continues at an ever increasing pace and has made available many new and effective drugs. These drugs form the basis of current nonsurgical treatment of disease. Some examples of these drugs are given in Table... 

But perhaps the pivotal event of nineteenth-century celestial mechanics was the successful prediction of the orbit of Neptune through the analysis of orbital perturbations on Uranus. Accomplished by Adams and Le Verrier, the discovery in 1846 of this hitherto unknown planet served to inspire much of the revived interest in orbital dynamies and the detailed exploration of perturbation theory. Significant contributions were made by Delaunay, Hill, Hansen, Brown, and Airy in this regard, especially concerning the motion of the moon (a problem that had even perplexed... 

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