Reproducibility defined

Figure 1.6. Repeatability and reproducibility are defined using historical data. The length of the time interval over which the parameter is reviewed is critical the shorter it is, the better defined the experimental boundary conditions tend to be the repeatability sets the limit on what could potentially be attained, the reproducibility defines what is attained in practice using a given set of instrumentation and SOPs.

Reproducibility, defined as the closeness of agreement between individual test results obtained with the same method on identical test material but in different laboratories with different operators using different equipment and not necessarily in short intervals of time. 

Appropriate SPE sorbent selection is critical to obtaining efficient SPE recovery of semivolatile organics from liquids. Henry [58] notes that an SPE sorbent must be able to sorb rapidly and reproducibly, defined quantities of sample components of interest. Fritz [73] states that successful SPE has two major requirements (1) a high, reproducible percentage of the analytical solutes must be taken up by the solid extractant and (2) the solutes must then be easily and completely eluted from the solid particles. The sorption process must be reversible. In addition to reversible sorption, SPE sorbents should be porous with large surface areas, be free of leachable impurities, exhibit stability toward the sample matrix and the elution solvents, and have good surface contact with the sample solution [68,73],... 

Reproducibility. Defined by the standard deviation of the results obtained by different laboratories. 

The determination of the consensus measurement reproducibility for HX-MS is an integral part of method validation, as its derived uncertainty supports the estimation of precision under reproducibility conditions. Measurement reproducibility is determined through a statistical analysis of HX-MS measurements conducted on the same protein sample in many laboratories. The results from this analysis can help investigators detect measurement variance due to different realizations of the HX-MS technique. For studies of unknowns, measurement reproducibility defines where measurements of D uptake differ statistically. It is expected that rigorously evaluated measurement reproducibility can foster a broader understanding and acceptance of HX-MS data. To date, no study leading to the determination of the measurement reproducibility of HX-MS has been reported. 

Our work has focused on the production of synthetic protein analogs of the four best knovm structural protein materials, silk, elastin, collagen, and keratin (Fi ite 1). Initially we set out to prove that synthetically designed protein polymers, which consisted of repeating structural blocks from natural structural proteins, could be produced by microbial synthesis. We demonstrated that these synthetic proteins would reproduce defined properties of their natural counterparts and that we... 

To operate the MPI or LPI equipment at stable and reprodncable inspection conditions modern units are equipped with a monitoring and control system called "Quality Assurance Package" (termed QAP). The QAP System is ba.sed on an industrial PC with a bus system and field sensors. It ensures that process parameters important for the reproducability of the MPI or LPI are controlled an held between defined limits by a central computer system. It can be adapted to any old system, as well as integrated into new systems. 

To define the thennodynamic state of a system one must specify fhe values of a minimum number of variables, enough to reproduce the system with all its macroscopic properties. If special forces (surface effecls, external fields—electric, magnetic, gravitational, etc) are absent, or if the bulk properties are insensitive to these forces, e.g. the weak terrestrial magnetic field, it ordinarily suffices—for a one-component system—to specify fliree variables, e.g. fhe femperature T, the pressure p and the number of moles n, or an equivalent set. For example, if the volume of a surface layer is negligible in comparison with the total volume, surface effects usually contribute negligibly to bulk thennodynamic properties. 

Before discussing the different ways of representing a chemical compound, some terms have to be defined concerning the reproducibility or transformation of structures and notations. 

The explicit definition of water molecules seems to be the best way to represent the bulk properties of the solvent correctly. If only a thin layer of explicitly defined solvent molecules is used (due to hmited computational resources), difficulties may rise to reproduce the bulk behavior of water, especially near the border with the vacuum. Even with the definition of a full solvent environment the results depend on the model used for this purpose. In the relative simple case of TIP3P and SPC, which are widely and successfully used, the atoms of the water molecule have fixed charges and fixed relative orientation. Even without internal motions and the charge polarization ability, TIP3P reproduces the bulk properties of water quite well. For a further discussion of other available solvent models, readers are referred to Chapter VII, Section 1.3.2 of the Handbook. Unfortunately, the more sophisticated the water models are (to reproduce the physical properties and thermodynamics of this outstanding solvent correctly), the more impractical they are for being used within molecular dynamics simulations. 

It is sometimes desirable to include the effect of the rest of the system, outside of the QM and MM regions. One way to do this is using periodic boundary conditions, as is done in liquid-state simulations. Some researchers have defined a potential that is intended to reproduce the effect of the bulk solvent. This solvent potential may be defined just for this type of calculation, or it may be a continuum solvation model as described in the next chapter. For solids, a set of point charges, called a Madelung potential, is often used. 

The pH value is defined for an aqueous solution in an operational (arbitrary but reproducible) manner according to the Bates-Guggenheim convention ... 

Documentation of experimental method so that work can be reproduced at a later time Appropriate data handling statistical methods conclusions based on fact, supportable by data Define and execute critical experiments to prove or disprove hypothesis Mechanistic or fundamental interpretation of data preferred Communication of Conclusions to Incorporate Technical Learning in Organization Experimental W rk Done in Support of New or Existing Processes Should be Captured in Process Models... 

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