Threshold definition

The NSR and RACT requirements apply to major stationary sources. The CAA s definition of major stationary source varies with the classification of the ozone nonattainment area. For marginal and moderate nonattainment areas a major stationary source for NOx is any stationary source that emits or has the potential to emit 100 tons per year or more of NOx. In the case of serious, severe, or extreme ozone nonattainment areas within the transport region, lower threshold definitions of major stationary source apply to NOx sources (50, 25 and 10 tons per year, respectively). 

Threshold lamit Value - The term refers to toxicity by inhalation. The abbreviation used is TLV. The TLV is usually expressed in units of parts per million (ppm) - i.e., the parts of vapor (gas) per million parts of contaminated air by volume at 25 °C (77°F) and atmospheric pressure. For chemicals that form a fine mist or dust, the concentration is given in milligrams per cubic meter (mg/m ). The TLV is defined as the concentration of the chemical in air that can be breathed for five consecutive eight-hour workdays (i.e., 40 hours per week) by most people without suffering adverse health effiects. This is the definition given by the American Conference of Governmental Industrial Hygienists. 

Maximum allowable concentration (MAC) An old American definition used before the term TLV came into use (the term is still used in Germany). See Threshold limit value (TLV). 

We recognize that 0id majority merely a special case of the generalized threshold rule defined in equation 5.121. In particulm-, majority may be defined using that more general definition by setting... 

As outlined in Section III.A, knowledge of the molecular wavefunction implies knowledge of the electron distribution. By setting a threshold value for this function, the molecular boundaries can be established, and the path is open to a definition of molecular shape. A quicker, but quite effective, approach to this entity is taken by assuming that each atom in a molecule contributes an electron sphere, and that the overall shape of a molecular object results from interpenetration of these spheres. The necessary radii can be obtained by working backwards from the results of MO calculations21, or from some kind of empirical fitting22. 

The construction starts at the root node of the tree, where all the available (x, y) pairs are initially placed. One identifies the particular split or test, s, that maximizes a given measure of information gain (Shannon and Weaver, 1964), 0(.s). The definition of a split, s, involves both the choice of the decision variable and the threshold to be used. Then, the (x, y) root node pairs are divided according to the best split found, and assigned to one of the children nodes emanating fi-om it. The information gain measure, 0is), for a particular parent node t, is... 

We can now revise Algorithm 1 with the definition of the error threshold. 

Peak width definition (threshold) Lets the computer know how to distinguish between true peaks and detector spikes. 

Endpoint/Concentration/Rationale Because the exposures did not result in effects consistent with the definition of an AEGL-3, the concentration vs percent hemoglobin formation data presented by the authors was graphed and projected to a methemoglobin level of 70-80%, which was considered the threshold for lethality in humans. This value was approximately 250 ppm. An 8-h exposure to 250 ppm was chosen as the basis for the AEGL-3 calculations. 

The most notable data deficiency is the absence of a well-defined exposure response relationship for monomethylhydrazine toxicity related to AEGL-2 effects. This deficiency precluded a definitive determination of the thresholds... 

Critical research needs include definition of thresholds for adverse health effects and how these thresholds vary with exposure concentration and duration. Such data would be valuable for affirming AEGL values. Additionally, the mode of dimethylhydrazine toxicity is not fully understood and, therefore, research providing insight into the underlying mechanism(s) of dimethylhydrazine toxicity would reduce current uncertainties in quantitative health risk issues. 

As in the molecular case (Dl), the definition (D2) allows the supramolecular unit(s) to be determined by an operational NBO search of a given electron distribution ir(fi, r2,..., Fjv ) 12. Given the NBO molecular units of the distribution, we can search the intermolecular interactions (e.g., the table of perturbative donor-acceptor stabilizations) to determine the connecting noncovalent bonds that satisfy the required thermal threshold, and thereby determine the contiguously bonded supramolecular unit(s) by (D2). 

Table 2-7 Definitions for Threshold Limit Values (TLVs)1...

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