Defining factors

The limit of detection is the smallest amount of an analyte that is required for reliable determination, identification or quantitation. More mathematically, it may be defined as that amount of analyte which produces a signal greater than the standard deviation of the background noise by a defined factor. Strictly for quantitative purposes, this should be referred to as the limit of determination . The factor used depends upon the task being carried out and for quantitative purposes a higher value is used than for identification. Typical values are 3 for identification and 5 or 10 for quantitation. 

The most clearly defined factors in determining the differentiation of Th responses are the cytokines present during T cell receptor engagement of the peptide MHC complex. IL-12 and IFN-y are important in the development of type 1 responses (Hsieh et al., 1993 Seder et al, 1993), while IL-4 is important in the induction of type 2 responses (Abishira-Amar et al., 1992 Seder et al., 1992). The importance of these cytokines in influencing... 

This minimal model can be used in many situations where one clearly defined factor is crucial for the quality of the product. It can be organised as a voluntary agreement between independent enterprises, or it can be imposed by a dominant enterprise such as a wholesaler or retailer, as a condition for obtaining a contract to sell products to this enterprise. 

Takahashi K, Tanabe K, Yamanaka S et al (2007) Induction of pluripotent stem cells from adult human fibroblasts by defined factors. Cell 131 861-872... 

The term "standard" is not meant to denote a digestion procedure which should be routinely used to determine potentially available calcium. Since the number of foods tested so far is limited, it will be more useful to think of the "standard" procedure as a set of conditions to be used to see how well we understand food chemistry and calcium solubility in the gastrointestinal environment. It should be used for measuring the relative solubility of calcium from foods and meals, but mostly in the context of comparisons with in vivo results to define factors which require further study. 

The Producing System. The questions of particular concern here are the nature of the system used to manufacture the desired substance, and the precision with which it is controlled. If the system consists of prokaryotic cells, then how well-defined is their provenance and how is their consistency demonstrated If mammalian cells are employed, their lineage must be considered. In both instances, it is important to ensure that extraneous virus, infections, DNA and less well-defined factors such as slow viruses are excluded by the origins and history of the producer strain, or because the physical (e.g., filtration) or chemical (pH, solvents, affinity separation) nature of the production process can be relied upon to exclude passage of an infectious agent. 

Sperling and coworkers looked at the question of how many chains are broken and the defining factors related to this breakage when a polymeric material is cut or broken. They used various chain lengths of PS, and employed a dental drill as the cutting implement. 

Considerable activity has been concerned with polymeric attachment of the 8-hydroxyquinoline heterocycle because of its excellent metal complexing ability. A comprehensive examination of attachment of the group to a variety of polymers has revealed that the overall capacity for a variety transition metals depends not only on the 8-hydroxyquinoline content but also on rather ill-defined factors introduced by the polymer modified (73MI11105). 

It is important once again to note that, when considering factors, all variables having the least possible chance to affect the research subject are included. It is better in such a situation to include more factors, for the nonessential ones will be rejected in the process of selection. An example of defining factors is shown in Table 2.9 ... 

Environmental data may be classified according to the level of associated total error as screening data and definitive data. These two data types are also different with respect to their intended use and QC elements. The selection of the type of data to collect depends on the project DQOs and is made in the planning phase. The realm of possible data uses and methods of data collection are the defining factors in the selection. 

At a time not too long ago, ethnic groups, or human races were defined by geography and appearence, most often simply by skin color, sometimes additionally by language. These factors are still considered by many people as main indicators, but at the present time, the scientifically defining factors are genetic differences between populations. 

These values are not accurate and cannot be reproduced in a reliable manner. It is due to the fact that apart from the easily definable factors (such as current density, material of electrodes, temperature, pressure etc.) the overvoltage also depends to a great degree on factors that cannot be controlled so easily i. e. on the state of the electrode surface, way of the mechanical treatment of the same, its past (i. e. whether it had been polarized beforehand or not) even traces of impurities prove important. The difficulties connected with the definition of surface properties of electrodes are aggravated by the variability of the overvoltage in the very course of electrolysis. 

Evidently further work will be needed to define factors in both the catalyst and feed character that can affect coking. 

The defining factor for the determination of selectivity on a-Al203-supported Ag catalysts is the strength of the Ag-O bond. The lower the Ag-O bond strength, the more selective is the adsorbed O atom. 

Theoretical generalization is not enough to evaluate the availability of metals to benthic fauna. In actual fact, the rate of uptake of any element and the extent of its retention in an organism are dependent on a number of ill-defined factors. As the data in Table 6 indicate, the extent of biological enrichment varies considerably between species. It is likely governed by ... 

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