Multiple replications

The summary suggests that a number of psychopathology taxa have been identified to date and some forms of psychopathology were found to be continuous. However, support for many of these taxa and continua is rather weak and replications are desperately needed. In fact, at this point we cannot say that the taxonic status of any of the DSM disorders is known with certainty. Constructs where the structure has been consistently supported (e.g., schizotypy or depression severity) do not map clearly on the DSM. Only a handful of taxometric studies have directly evaluated DSM diagnoses, and multiple replications are needed before any firm conclusions can be drawn. 

The complexity of the method in terms of number of steps and solvents needed depends on the sorbent chemistry. The development in a simplified scenario involves running an analyte in several concentrations in multiple replicates and assaying for recovery and performance. This procedure is described in detail for several silica and polymeric sorbents by Wells.42 However, if a number of sorbents are to be evaluated, the process becomes time-consuming if multiple 96-well plates (each with one sorbent packed in all the wells) must be screened separately. This process may take a week or more and consume an analyst s precious time as well. The most plausible solution is to pack different sorbents in the same well plate and use a universal procedure that applies to all of them. An example of such a multisorbent method development plate is the four-sorbent plate recently introduced by Phenomenex demonstrated124 to require only 1 to 2 hr to determine optimal sorbent and SPE conditions. 

External precision is the ability to demonstrate analytical repeatability with multiple preparations and analyses of a material over a long period of time. The MC-ICP-MS techniques and the more widespread TIMS methods either demonstrate or claim external precisions in the range 0.5 to 1.0%o (2ct). The stated precision for most TIMS methods is estimated from the reproducibility of the L-SVEC standard. In many cases the analysis of individual samples prepared multiple times yields precisions poorer than this estimate. This is in part due to the heterogeneity of natural samples and in part due to effects introduced during preparation and analysis that are not experienced by the standard. Zhang et al. (1998) cite reproducibility of the L-SVEC standard of <1.0%o (2ct), but their duplicate measurements of individual pore water samples vary from 0.1 %o to 6.1 %o (mean 2.3%o all 2cj). Later studies using refined TIMS procedures appear to achieve superior replicate precision (e.g., 0.4%o to 1. l%o for multiple replicates in Chan et al. 2002c). 

Experiments 10-27 are designed to check the autosampler injection precision, pump repeatability and detector/system linearity. One programs the system to automatically inject multiple replicate volumes of a certified test standard. One typically injects 6-10 replicates per volume. The standard component s peak areas are used for calculated injection precision (reproducibility) and system linearity whereas, the retention times are used to calculate pump repeatability. 

Repeatability of a method can be determined by multiple replicate preparations of the same sample. This can be done either by multiple sample preparations (n = 6) in the same experiment or by preparing three replicates at three different concentrations. In general, one should evaluate results of individual related substances, total related substances, and the consistency of related substance profiles in all experiments. The percent RSD and confidence level of these results are reported to illustrate the method repeatability. 

Number of Samples Multiple replicates (six samples are recommended) to determine the release rate (profile) of the topical dermatological product. 

Unique sequences (genes), dispersed repeats, and multiple replication origins... 

Precision is the agreement between the measurements of the same property under a given set of conditions. Precision or random error is a quantitative parameter that can be calculated in several different ways as the standard deviation relative standard deviation (RSD) or as relative percent difference (RPD). The first two are common statistical parameters that are used for the evaluation of multiple replicate measurements, whereas RPD is used for measuring precision between two duplicate measurements. Equation 1 in Table 2.2 illustrates the method for calculating RPD as a measure of precision. 

These template polymerizations suffer from three fundamental problems (i) In most cases the binding of the polymer to the template is stronger than the binding of the monomer due to the cooperativity of the interaction between the polymers. As a consequence the newly formed macromolecules are not released from the template and multiple replication is not possible without multiple separation steps, (ii) We lack the possibility to start the polymerisation reaction at the terminal group of the monomer-template complex, (iii) While a weak interaction between the template and the monomer is favourable to allow easy separation of the template and the newly formed macromolecule, it leads to incomplete complexation of the template and interraption of the polymerisation along the chain. A solution of these problems would require a relatively strong complexation of the monomers in combination with sufficient anticooperativity in the complexation of the polymer. The latter however would inevitably impede the polymerisation reaction and require therefore a living polymerisation mechanism which does not suffer from a slowed down rate of polymerisation. 

Fig. 1. Comparative chromosomal organization of prokaryotes and eukaryotes. The question mark indicates that we do not know whether archaebacteria have a single origin or multiple replication origins. The diagrams correspond to the average situation a few eubacteria have linear chromosomes but without telomeres whereas some eubacteria and Haloferax species have several circular chromosomes and/or giant plasmids. The cell size is also only indicative a few eubacteria are bigger...

An interesting aspect of the template effect also dependent on electrostatic interactions, is the parabolic self-multiplication - replication - with the aid of amidinium carboxylate bridges (Scheme 6) [25 a]. Replication generally takes place by way of (-1-)- or (-)-strands The (-i-)-strand, as matrix, catalyzes formation of the (-)-strand and vice versa. In the self-complementary (palindromic)... 

The ideal chemical isotopic tag is one that will react with every protein or peptide present in the sample and be reactive enough that the protein/peptide becomes fully labeled. However, the intrinsic reactivity of the compound should not be so high that it degrades upon storage under proper conditions. Also, the ideal tag will be stable upon mass spectrometry and not readily break apart under standard conditions. The ideal chemical tag will either be commercially available or relatively easy to synthesize, and the price should be reasonable. At a minimum, the tag needs to be available in a heavy and light form, but ideally would be available in a range of masses so that multiple replicates can be combined. It is also important that peptides labeled with the heavy and light forms of the tag coelute from HPLC otherwise, the quantitation is less accurate when... 

Consequently, approximately one month is required for this DNA replication. Eukaryotic DNA synthesis is significantly faster than expected because each chromosome contains multiple replication units (replicons). 

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