Type B evaluation

Type B evaluation (of uncertainty) Method of evaluation of uncertainty by means other than the statistical analysis of series of observations. [Definitions from VIM]... 

Each contribution is assessed as a standard uncertainty, either by statistical procedure on experimental data in the form of an a posteriori distribution, the so-called Type A evaluation, or by scientific judgement based on an a priori chosen distribution, Type B evaluation. The few standard uncertainties of important magnitude are combined quadraticahy, including any covariances, and the combined uncertainty, uc, is obtained as the positive square root. 

Many methods of uncertainty evaluation do not involve the statistical analysis of series of observations these are called Type B evaluations. One of the most common Type B methods of uncertainty evaluation in radioanalytical chemistry is the common practice of estimating the standard uncertainty of an observed count C by its square root Vc (see Section 10.3.4). 

Another way to perform a Type B evaluation is to estimate the maximum possible absolute error b in an input estimate jc, and to assume that the distribution of the estimator is either rectangular or triangular, with half-width equal to To evaluate the standard deviation of the estimator, if the distribution is rectangular with halfwidth b, the standard deviation (i.e., the standard uncertainty of x, ) equals A/3. If the distribution is triangular, the standard deviation equals b/. ... 

Given these assumptions, the distribution of the observed total number of counts according to probability theory should be binomial with parameters N and p. Because p is so small, this binomial distribution is approximated very well by the Poisson distribution with parameter Np, which has a mean of Np, and a standard deviation of Np. The mean and variance of a Poisson distribution are numerically equal so, a single counting measurement provides an estimate of the mean of the distribution Np and its square root is an estimate of the standard deviation /Np. When this Poisson approximation is valid, one may estimate the standard uncertainty of the counting measurement without repeating the measurement (a Type B evaluation of uncertainty). 

This article adopted the measurement uncertainty assessment methods, which contains type A and type B evaluation methods, to evaluate the uncertainty of gas flow measurement via pitot tube. The synthesis of relative standard uncertainty is acquired for the flow velocity measurement. 

Depending on the method for deterrnining uncertainty components, the GUM distinguishes between type A and type B evaluations. Type A evaluations are based on a statistical analysis of a measurement series type B evaluations cover all other methods based on the available knowledge. Both components are combined and... 

Quantifying the main uncertainty contributions. Each of the input quantities receives a standard uncertainty m(x ) either in the form of a standard deviation of a measurement series (type A evaluation) or a standard deviation of a reasonable distribution of values (type B evaluation). In case of a normal... 

Note 3 Measurement uncertainty comprises, in general, many components. Some of these may be evaluated by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity values from series of measurements and can be characterized by experimental standard deviations. The other components, which may be evaluated by Type B evaluation of measurement uncertainty, can also be characterized by standard deviations, evaluated from probability density functions based on experience or other information. The meaning of Type A and Type B will be clarified further in the text. 

The NRC also imposes special security requirements for spent fuel shipments and transport of highly enriched uranium or plutonium materials that can be used in the manufacture of nuclear weapons. These security measures include route evaluation, escort personnel and vehicles, communications capabiHties, and emergency plans. State governments are notified in advance of any planned shipment within their state of spent fuel, or any other radioactive materials requiring shipment in accident-proof. Type B containers. 

When the system contains more than one component it is important to be able to explore the distribution of the different components both locally and at long range. One way in which this can be achieved is to evaluate the distribution function for the different species. For example in a binary mixture of components A and B there are four radial distribution functions, g (r), g (r), g (r) and g (r) which are independent under certain conditions. More importantly they would, with the usual definition, be concentration dependent even in the absence of correlations between the particles. It is convenient to remove this concentration dependence by normalising the distribution function via the concentrations of the components [26]. Thus the radial distribution function of g (r) which gives the probability of finding a molecule of type B given one of type A at the origin is obtained from... 

If one includes functions with n - / even in (1.1) (i.e. one uses set b) the basis is formally overcomplete. However the error decreases exponentially with the size of the basis [2,16]. Unfortunately for this type ofbasis the evaluation of the integrals is practically as difficult as for Slater type basis functions, such that basis sets of type (b) have not been used in practice. 

Note Conventional safety pharmacology studies can reasonably be expected to predict "Type A" ADRs. Functional toxicological measurements may predict "Type C" ADRs. Conventional toxicology studies address "Type D" ADRs. Prediction of "Type B" responses requires a more extensive non-clinical and clinical evaluation, often only addressing risk factors for the idiosyncratic response. "Type E" ADRs are rarely investigated non-clinically using functional measurements unless there is cause for concern. 

Construction of the Hup mutant strain by interposon mutagenesis (A) and evaluation test of its hydrogen photoproduction performace in comparison to the wild type (B) (courtesy of Enitecnologie, Milano). 

J. Wouters, Rational approaches towards reversible inhibition of type B monoamine oxidase. Design and evaluation of a novel 5H-indeno[1,2-c]pyridazin-5-one derivative, Bioorg. Med. Chem. Lett. 13 (2003) 69-73. 

The 3d ab initio simulations [4] for Na3 are based, in a similar way, on three ab initio potential-energy surfaces for Na3(X), Na3(B), and Na3(X), with 3d ab initio dipole coupling between Na3(X) and Na3(B) evaluated by V. Bonacic-Koutecky et al. [5] plus Condon-type coupling between Na3(B) and Na3(X). Additional potential-energy surfaces interfere at the conical intersections of the pseudo-Jahn-Teller distorted Na3(B) state (see Ref. 6), but we have tested carefully [4] that these interferences are negligible in the frequency domains of the experimental femtosecond/picosecond laser pulse experiments [7] as well as in the continuous-wave experiments [8]. 

Gill JC, Ottum M, Schwartz B. Evaluation of high concentration intranasal and intravenous desmopressin in pediatric patients with mild hemophilia A or mild-to-moderate type 1 von Willebrand disease. J Pediatr 2002 140(5) 595-9. 

The distinction between the two categories of uncertainties (types A and B) is based on the method of their evaluation. Those of type A, but not those of type B, can be evaluated by statistical methods [6], These categories do not correspond exactly to the former grouping of uncertainties into random and systematic. No distinction is made between types A and B for the combination of uncertainties... 

Ubelaker, D. H., Buchholz, B. A., and Stewart, J. E. B. (2006). Analysis of artificial radiocarbon in different skeletal and dental tissue types to evaluate date of death. /. Forensic Sci. 51, 484-488. 

While scant literature is available on persistence and distribution after inhalation exposure, several studies have evaluated the systemic behavior of parenterally administered toxins. One group investigated toxin persistence in serum and tissue distribution in white mice following intravenous (IV) administration of 1,000 lethal doses of S-labeled type B toxin (Pak and Bulatova, 1962). Mice were sacrificed at 20, 60, and 150 min after toxin administration, and blood and tissues were harvested for toxin distribution analysis. These mice showed symptoms of severe intoxication, including atypical breathing patterns and paralysis, at 150 min post-exposure. Toxin levels (as determined by... 

Two reaction mechanisms were proposed [602] a) the catalyst acts as a simple adsorbent on which the reactants react on the surface (Langmuir-Hinshelwood type) b) the active catalyst sites are successively oxidized and reduced by the adsorbed reactants (Rideal-Eley type). Evaluation of the vast amount of experimental material leads to the conclusion that the HT shift (and also the LT shift) proceeds via mechanism (b), which schematically may be formulated as shown in Figure 62. 

The cyclobutane radical cation was calculated by several groups, who evaluated Jahn-Teller distorted structures potentially arising upon ionization of cyclobutane [79, 83-87]. Four distorted local minima were considered (Figure 13). A rectangular structure with two weakened C-C bonds (type A) and a rhomboidal structure with four weakened C-C bonds (type B) result from first order Jahn-Teller distortion. Two further structures, a trapezoidal one (one weakened C-C bond type C), and an irregular structure shaped like a kite (two lengthened C-C bonds type D) can be envisaged as a consequence of second-order Jahn-Teller distortion [86]. A detailed recent study also considered puckered equivalents of the planar structure types, A-D... 

Other substances that are being evaluated in Alzheimer s disease include the antioxidant vitamin E, the monoamine oxidase type B inhibitor, selegeline (see p. 425) and the plant extract gingko biloba, which is though to have antioxidant and cholinergic activity. Oestrogens and nonsteroidal anti-inflammatory agents may also have protective effects. 

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