Acceptance tests sensitivity

MULTIPLE CHEMICAL SENSITIVITY An acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to many chemically-unrelated compounds at doses far below those established in the general population to cause harmful effects. No single widely accepted test of physiologic function can be shown to coiTelate with symptoms. 

D. A. Basketter, G. F. Gerberick, I. Kimber, and S. E. Loveless. The local lymph node assay A viable alternative to currently accepted skin sensitization tests. Food Chem. Toxicol. 34 985-997 (1996). 

The most commonly accepted definition of MCS was written by Mark Cullen, M.D., a professor of medicine and epidemiology at Yale University. In Workers With Multiple Chemical Sensitivities, Occupational Medicine 2 (1987) 655-626, he writes, Multiple chemical sensitivities is an acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful elfects. No single widely accepted test of physiologic function can be shown to correlate with symptoms. ... 

The term sensitiveness is sometimes used, particularly in British literature, to define the quality of being sensitive, when it connotes the hazard level associated with an explosive. In this usage sensitivity is a term reserved for the effectiveness or performance level of the explosive. The distinction is by no means universally accepted, and as will be clear from the content of this chapter, both measures are often based on explosions which occur with a relatively high probability. When testing sensitive explosives, such as azides, the range of stimuli directed at samples does not vary greatly, and the probability ranges encountered... 

Most of the standardized and well-accepted test methods evaluate the susceptibility of aerobic, nonfastidious bacteria. However, substantial progress has been made in the past decade toward the development of sensitive, specific, reproducible, and clinically useful susceptibility tests for anaerobic bacteria, yeasts, mycobacteria, and viruses. Continued advances in technology should further improve test methods and the rapidity with which the results can be applied to the management of patients. Although these newer systems are often very expensive, the increased quality and decreased overall costs of patient care may determine their cost-effectiveness. 

Sensitivity is given by volume sensitivity expressed in units of kcps/pCi/cc or cps/Bq/cc. It is determined by acquiring data in all projections for a given duration from a volume of activity (uniformly mixed) and dividing the total counts by the duration of counting and by the concentration of the activity in the source. Manufacturers normally use this unit as a specification for the PET scanners. The detailed method of determining volume sensitivity is described under acceptance tests in this chapter. The volume sensitivities of PET scanners from different manufacturers are given in Table 6.1. 

Acceptance tests are a battery of quality control tests performed to verify various parameters specified by the manufacturer for a PET scanner. These are essentially carried out soon after a PET scanner is installed in order to establish the compliance of specifications of the device. The most common and important specifications are transverse radial, transverse tangential, and axial resolutions sensitivity scatter fraction and count rate performance, ft is essential to have a standard for performing these tests so that a meaningful comparison of scanners from different manufacturers can be made. 

What are acceptance tests Describe the methods of determining sensitivity and scatter fraction for a PET scanner. 

Most of the Type II circuits required no particular refinement due to the relatively large capacitance change available. However, instances of false indications due to a decrease in capacitance with temperature were noted during preliminary acceptance testing. The majority of the Type II units are sensitive to cable length. 

Not surprisingly listeners exhibit biases related to hearing ability, and to a lesser extent, age. Broadband sensitivity is apparently the most important factor in the reliability of most test subjects evaluating loudspeaker systems. It is estimated that approximately 60% of the population possess acceptable broadband sensitivity to be reliable test subjects. It has been noted that stereo assessments tend to obscure slightly the discernment of typical listeners. Monophonic tests of the same loudspeaker systems revealed a more heightened sensitivity to colorations than when hsteners heard the systems in stereo. 

In terms of the data in Fig. 15, the requirement as mentioned above for freedom of sensitization corresponds to a requirement for a step structure in the oxalic acid etch test. Even though the oxalic acid etch is not a quantitative test, the step microstructure can be readily identified and has been used for laboratory acceptance testing in industry for more than 40 years to identify and screen acceptable material which needs no further testing in one of the boiling tests that provide quantitative data. The much simpler oxalic acid etch test also has been used as a nondestructive test on equipment in chemical plants. 

The third commonly used sensitization test method is called the mouse local lymph node assay (LLNA). The LLNA is an acceptable test method, but device manufacturers have been using the guinea pig tests for decades and are satisfied with the results obtained using those methods. The LLNA, like any test, has its pros and cons. On the positive side, it is shorter in duration, uses animals of a lower phylum, and requires far less test material. However, it also generates radioactive waste and is not accurate in distinguishing a sensitization response from an irritation response, which increases the possibility of a false-positive outcome. 

Until recently, there have been only two primary techniques available for the detection of botulinum neurotoxins. The first of these, which is the most widely accepted and sensitive technique for the detection of botulinum neurotoxins in semm and food extracts, is the mouse bioassay (Sakaguchi, 1983). Although the mouse bioassay is the most sensitive method, with the ability to detect less than 5 mouse 50% lethal doses (MLD5os)/mL, the assay takes up to four days to complete and requires a large number of mice if the toxin is to be quantified. In addition, the mouse toxicity results are not in themselves specific specificity is imparted only by carrying out parallel toxin neutralization tests with homologous antisera (Shone et al., 1985). Furthermore, as future modifications are made to botulinum neurotoxins relative to their use as therapeutic agents, quantification relative to its toxicity to mice may not be possible. Thus, despite the apparent sensitivity offered by the mouse bioassay, its use as a routine detection technique for botulinum neurotoxins is not only impractical, but also may be obsolete in some areas of research. 

The computer also can leam from a defect-free test piece by rutming such a piece in a readmode. For example, if a drilled hole for lubrication purposes is present at the same location on all parts, the computer will recognise this signal and accept it on all test pieces. The computer will actually be comparing the test piece under scrutiny with standard non-defect master. In addition a reference test piece should be used to check that the specified reference defects really will be detected. This is needed to adjust the settings and sensitivity of the system. 

A particular mode of neurotoxicity was discovered for tricresyl phosphate that correlated with the presence of the o-cresyl isomer (or certain other specific aLkylphenyl isomers) in the triaryl phosphates. Many details of the chemistry and biochemistry of the toxic process have been elucidated (139,140,143—146). The use of low ortho-content cresols has become the accepted practice in industrial production of tricresyl phosphate. Standard in vivo tests, usually conducted with chickens sensitive to this mode of toxicity, have been developed for premarket testing of new or modified triaryl phosphates. As of 1992, the EPA called for extensive new toxicity and environmental data on this group of products (147). The Vederal e ster AoQ xm. ci. calling for this... 

Maximum acceptable concentiation figures expressed as fractions of 96 h for most sensitive species in given area. The 96 h is that concentration of a substance which kills 50% of the test species within 96 h under standard bioassay conditions. 

Specifications and Standards. Typical specifications for phthahc anhydride are given in Table 10. AH specifications are measures of purity. Sohdification point is a sensitive indicator of absolute purity, and is a key specification. Another key specification is molten color stabiUty, which is the color after being held at 250°C for two hours. This test ensures acceptable color after shipment in molten form and detects the presence of impurities that can cause discoloration at elevated temperatures. Phthahc acid level is a monitor of how well moisture has been excluded during storage and shipment. 

Environmental. The toxicity of cyanide in the aquatic environment or natural waters is a result of free cyanide, ie, as HCN and CN . These forms, rather than complexed forms such as iron cyanides, determine the lethal toxicity to fish. Complexed cyanides may revert to free cyanide under uv radiation, but the rate is too slow to be a significant toxicity factor. Much work has been done to estabhsh stream and effluent limits for cyanide to avoid harmful effects on aquatic life. Fish are extremely sensitive to cyanide, and the many tests indicate that a free cyanide stream concentration of 0.05 mg/L is acceptable (46), but some species are sensitive to even lower concentrations. 

The important question, then, is not whether a substance is pure but whether a given sample is sufficiently pure for some intended purpose. That is, are the contaminants likely to interfere in the process or measurement that is to be studied. By suitable manipulation it is often possible to reduce levels of impurities to acceptable limits, but absolute purity is an ideal which, no matter how closely approached, can never be attained. A negative physical or chemical test indicates only that the amount of an impurity in a substance lies below a certain sensitivity level no test can demonstrate that a specified impurity is entirely al ent. 

The information obtained during the background search and from the source inspection will enable selection of the test procedure to be used. The choice will be based on the answers to several questions (1) What are the legal requirements For specific sources there may be only one acceptable method. (2) What range of accuracy is desirable Should the sample be collected by a procedure that is 5% accurate, or should a statistical technique be used on data from eight tests at 10% accuracy Costs of different test methods will certainly be a consideration here. (3) Which sampling and analytical methods are available that will give the required accuracy for the estimated concentration An Orsat gas analyzer with a sensitivity limit of 0.02% would not be chosen to sample carbon monoxide... 

Optimized grit blast/silane treatments can provide wedge test durability as good as PAA with failure entirely cohesive within the adhesive (Fig. 21) [89]. Maintaining the process parameters within acceptable tolerances is critical with the heat drying of the silane on the treated surface being the most sensitive process parameter. 

This report presents an analysis of DG unavailability, caused both by failure occurring while the DG is on standby and test-caused failures. The report presents a methodology for determining testing intervals (TIs) so that diesel unavailability is at an acceptably low level. Sensitivity analyses of test unavailability to varying TIs are presented. 

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