Replication artifacts

Clean Water Blank Experiment. This experiment was performed for the purpose of identifying any artifacts that might arise from the resin in the course of normal resin experiments. Four replicate resin blanks were run by the normal resin separation-concentration procedure. Data from this experiment yielded the following conclusions ... 

SEM-EDS was not performed with the replicated samples before using it on the actual artifacts, because its frequent application to analyze historic and archaeological fibers has verified its usefulness. 

Using forensic photography as a precursor to any sample acquisition forms the foundation of the protocol, and allows purposive sampling. EDS should be performed to establish which elements to expect before attempting any quantitative elemental analysis such as ICP-OES/MS. Before working with actual artifacts, a set of replicated materials must be used and a successful trial run using the planned methods of analysis whether ICP-OES/MS, GC-MS or any others, must be achieved, so the methods of preparation can be adjusted properly. To facilitate this, appropriate materials must be replicated, which might mean that plants or minerals must be collected, and dyed or painted comparative standards must be created, so the unknown can be compared to the known. For many of the Old World dye plants these standards already exist. However, for North American dye plants comparative collections are in the early phases and subsequent analysis of colorant constituents have not yet been conducted (68,69). 

The answer is that artifacts originate in the human mind as mental objects, and afterwards are turned by man into physical objects (this is true even for a poem which must become ink on paper or soundwaves in air). Artifacts have therefore a genotype and a phenotype. The genotype of the pen that I am writing with is the idea that was born in its inventor s mind, and which was replicated countless times in the blueprints of its mass production. The real pen that my hand is holding is an inanimate object because it is a pure phenotype, a phenotype which is physically separated from its genotype, but I could never understand its existence if I didn t keep in mind that this physical object came from a mental object. 

Unfortunately the surface of the complexed sample cannot be replicated and examined by electron microscopy because the solvents normally used perturb the complex by introducing artifacts. However scanning electron micrographs of these fracture surfaces indicate that the morphology of the original polymer is modified considerably by the I2-KI treatment—a fact consistent with the wide angle x-ray and other evidence. It has been pointed out elsewhere (11) that thin films and fibers of complexed polyamides are very pliable and often putty-like when first removed from the complexing solution this fact is consistent... 

Dorinson and Broman [3, 4, 5] have published data for many replicate experiments which demonstrate that the structured curves seen in Fig. 13-2 are reliable patterns of behavior and not artifacts due to imprecise and unreproducible experimental results. The three-stage curve can be regarded as characteristic behavior for wear in the presence of non-compounded petroleum oils under moderately severe pressure conditions. At extremely high contact pressures it is difficult to discern such structured behavior in the course of the wear process because of the dispersion and the poor reproducibility of the data at very low pressures the structure of the curve shows only the transition from the initial rate to a stable phase with a much lower rate and the final transition to a higher rate does not appear at all. 

Sediment traps are intended to measure downward flux, but technical diflBculties may affect interpretation of the results. Loss of trapped material during recovery is still a problem (53,55), and replication is not always good (55) because the traps affect the flow of water around them (cf. Ref. 66). Also, trapping of what is really resuspended benthic material may create artifacts (for example, 67), even a few hundred meters off the bottom of the deep sea (55). 

Unlike DNA diagnostics with clinical samples, where the amount of DNA in a volume of blood or other biological fluid can be estimated with little consequence, postpurification DNAquantification is of the utmost importance in forensic sample analysis. The target mass of DNA required for effective use of the commercially available STR kits is 1 ng. When a reduced mass of DNA is added to the PCR, stochastic effects that could include allelic dropout, may make interpretation difficult. Alternatively, an excess of DNA in the PCR (>5 ng) can result in off-scale peaks, pull-up (color bleeding usually due to off-scale peaks), increased levels of stutter (small peaks typically one repeat unit shorter than the STR allele, believed to be due to slippage of the primer or template during replication) or other artifacts in the subsequent electrophoretic separation. 

Over the years there have been many anecdotes and much controversy over the wide variations in silica properties reported in the literature and the mechanisms of the processes by which silica and silicate species exert their influence. Much of the discussion results from the fact that both the exact nature of the speciation of silica in diluted solution and at the interface between sdicas and silicates and water and how this speciation changes in mixtures with other substances is unclear (25,26). Also, from a very practical standpoint sdica in some form is already present in many natural systems and in vitro experiments must seek to replicate the speciation to have any chance of learning from them. Complicating the situation, the extensive literature contains many observations drawn from experiments carried out under conditions where soluble silica might have been present in an uncontrolled manner and at concentrations sufficient to exert significant effects or conclusions drawn from insufficient mathematical models. The high potential for artifacts, which can influence the behavior of silica, even in the simplest systems, was well characterized by Hazel (my first college chemistry professor) [27], Debye [28] and Her [29] who made it clear that one had to be aware of the purity and/or preparation history of the silica. 

For several reasons, the interphase chromosome scaffold remains the most controversial of karyoskeletal elements. For example, it is currently uncertain whether the scaffold is one contiguous element, several discrete elements, or an in vitro artifact without biological significance. Nevertheless, roles for the scaffold in DNA replication, transcription, splicing, and (perhaps) mRNA export have been proposed. In the current context, it is critical to distinguish the interphase scaffold, referred to herein, from the mitotic or metaphase scaffold, studied extensively by others [for a review, see Saitoh and Laemmli (1993) and references therein]. 

Another trap is the fact that very often the art object has been restored using materials superficially similar to, but quite different from, the original (e.g., beeswax substituted by paraffin). Identification of this later addition could lead one to misleading conclusions. A further stumbling block is the understandable reluctance of curators to provide samples of adequate size. In practical terms, it means that it is very difficult to undertake controlled or replicate experiments to confirm or reject ambiguous results. Similarly, the extremely small size of the sample leads one to ask how representative it is. This is especially the case when artists use mixed media (or vary composition throughout the artifact). 

Analytical investigations also focus on new ways of protecting susceptible materials that have not yet shown signs of degradation. The continued efforts to replicate archaeological artifacts and antiques and subject them to accelerated deterioration experiments provide useful results in the development of new treatments. Much can be learned from understanding how compositions deteriorate due to their inherent incompatibility or instability to external agents. 

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