Remote probability

For a conventional trial, with concurrent controls, things would be a little more complex. Here we would have to judge the efficacy of the treatment compared with the control group being studied at the same time. Nevertheless, a point can be reached in a conventional trial at which, whatever the future results are, the trial will be significant. However, most trialists would want to stop a trial even if statistical significance at the end was a theoretical but remote probability. If the trial is stopped or extended on the basis of some calculation of what the likely conclusion might be, then this approach is referred to as stochastic curtailment. 

At least two dozen different risk assessment code (RAC) matrices are in use. They all are based on severity on one axis and probability on the other, but the size and layout of individual matrices vary significantly. Some have severity on the vertical axis others have it on the horizontal axis. One makes the low numbers bad (an RAC of 1 indicates a high probability of a catastrophic accident), whereas the next uses a 1 to indicate a very remote probability of an insignificant loss. Some use RACs from 1 to 4 others use 1 to 16 still others use a combination of numbers, roman numerals, and/or letters (II to 4V or lA to 5D). 

A remote probability of occurrence dnring the item operating time interval (i.e. 

If recommendations given below are implemented, particularly the 24-hr purge, monitoring to 3X levels, removal of porous parts exposed to the agent, and replacement of tubing, the probability of agent exposure for contractor personnel is categorized as D, remote probability. ... 

Occurrence This is the likelihood of the event happening (i.e. failme in the system) on the basis that the cause occurs . FMEA assrrmes that if the cause occurs, failure will occur too. The probability of occirrrence is ranked from 1 to 10, where 1 signifies a remote probability of occirrrence and 10 a very high probability of occurrence. 

For investigators, even if a catastrophic accident is calculated to be a remote probability, it is still a permanent possibility. A vivid illustration of the strength of this belief is provided by Extended Twin Engine Operations, ETOPS, where twin engine aircraft such as Boeing 777 are... 

This matrix also classifies risk of each hazard into three levels high, medium, and low. This matrix is useful if there is a need to allocate a risk allocation to the JAR/FAR criteria. However, be careful to distinguish between hazards and accidents, which could both be allocated the same risk level. For instance, an accident which has a remote probability of killing a small number of persons should surely have a higher risk level that a hazardous failure condition (such as loss of attitude data) which is also remote in occurrence. 

We will discuss the structural and mechanistic basis of Cram s rule in Chapter 3. As would probably be expected, the influence of a stereogenic center on the diastereoselec-tivity of the reaction is diminished when the center is more remote from the reaction site. 

The objective is to estimate, numerically, the probability that a system composed of many components will fail. The obvious question is, "Why don t you just estimate the failure rate of the system from operating experience " There are three reasons IJ the system may not exist, so new data are not available, 2) the injuries and fatalities from the developmental learning experience are unacceptable - the risk must be known ahead of time, and 3) by designing redundancy, the probability of the system failing can be made acceptably remote in which case system failure data caimot be collected directly. The only practical way uses part failure statistics in a system model to estimate the system s reliability. 

It would be going too far to say that no one should ever enter a cloud of flammable vapor to isolate a leak. There have been occasions when, by taking a risk for a minute, a man has isolated a leak that would otherwise have spread a long way and probably ignited, perhaps exploded. However, we should try to avoid putting people in such situations by providing remotely operated emergency isolation valves to isolate likely sources of leak. 

A credible spill for Probable Maximum Loss Potential. The minimum spill source is the largest process vessel. The maximum spill size is the combined contents of the largest process vessel, or train of process vessels connected together if not readily isolated. Between these extremes, a credible spill may be estimated after taking into account the presence of remotely operated shutoff valves adequate for an emergency, and automatic dump or flare systems. 

Keep in mind, however, that ranking facilities on this basis does not account for the impact of the potential hazards on surrounding communities. It may be that your most hazardous facilities are located in remote, unpopulated areas where there is little probability of any injuries outside the plant perimeter. 

Both time-related failure rates and demand-related failure rates can apply to and be reported for many pieces of equipment. Both types of rates are included in some of the data tables in Chapter 5. If a piece of equipment is in continuous service, such as a transformer, the failure rate is dominated by time-related stresses compared to demand-related stresses. Other failure rates may be dominated by demands. Take a piece of wire and repeatedly bend it. With each bend its probability of catastrophic failure increases. In a relatively short time, if the bending is continued, the wire will fail. On the other hand, the same wire could be installed in a manner that would prevent mechanical bending demands. In this case, the occurrence of catastrophic wire breakage would be remote. In the first instance, the failure rate is dominated by demand stresses and in the second by time-related stresses, such as corrosion. 

Fluorophenylacetyl and 4-fluorophenylacetyl chlorides selectively ac-ylated the C8-NH2 group of 7,8-diamino-l,2,4-triazolo[l,5-c]pyrimidine 139 (94JHC1171) to give 140 (Scheme 54) N6 of the ring system probably renders the closer C7-NH2 group less nucleophilic than the remoter C8-NH2 function. 

Room-temperature fluorescence (RTF) has been used to determine the emission characteristics of a wide variety of materials relative to the wavelengths of selected Fraunhofer lines in support of the Fraunhofer luminescence detector remote-sensing instrument. RTF techniques are now used in the compilation of excitation-emission-matrix (EEM) fluorescence "signatures" of materials. The spectral data are collected with a Perkin-Elraer MPF-44B Fluorescence Spectrometer interfaced to an Apple 11+ personal computer. EEM fluorescence data can be displayed as 3-D perspective plots, contour plots, or "color-contour" images. The integrated intensity for selected Fraunhofer lines can also be directly extracted from the EEM data rather than being collected with a separate procedure. Fluorescence, chemical, and mineralogical data will be statistically analyzed to determine the probable physical and/or chemical causes of the fluorescence. 

The present information does not allow discrimination between these two routes. The high-pH path probably involves concerted attack of OH and Mn04 upon neutral amine because the possibility of attack of oxidant upon C6H5CH2NH or C6H5CHNH2 is too remote in view of known acidities of amines. 

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