Bias restraint

The second general method for performing PMF calculations relies on the use of Umbrella Sampling.50 In its simplest form, Umbrella Sampling adds a bias restraint (umbrella) term to the standard potential function... 

The accuracy of a procedure for structure determination can also be assessed using NMR data simulated for model structures 238-240,326 Using this approach, a possible bias in refined structures due to a particular choice of computational procedure, force field, number and type of experimental restraints, and so on can be investigated. However, the source of the bias may also be due to experimental data, such as mis-assignments, incorrectly estimated experimental errors, or conformational averaging. 

There are certain practical aspects that need to be taken into account in assessing the significance of temperature factors. Errors in measurement of intensities, arising for example from incomplete correction of radiation damage or absorption, will have more serious effects on temperature factors than on atomic positions. The data must extend to a resolution of better than 2 A, otherwise temperature factors tend to be underestimated. Restraints in the refinement which assume that positional disorders of bonded atoms are highly correlated may bias the results. However, it is encouraging that in several structures (e.g., rubredoxin [193] and avian pancreatic polypeptide [194]) where the restraints were relaxed these assumptions were found to be valid. 

Elbicki etal. 984) reviewed the optimum configurations for each of the above electrodes (thin-layer, tubular, and wall-jet) based on a mathematical treatment of the diffusive and convective phenomena in force. Boundary conditions on such physical restraints as electrode area, cell dimensions, and inlet configuration were established. Some confusion in the past has resulted from misinterpreting these equations (Weber, 1983) they are derived for cells in which the boundary layer may freely grow unencumbered. In certain cells (e.g., low-volume wall-jet or long-channel electrodes), walls, nozzles, etc. may impede the growth of the diffusion layer and bias the output current expected. Under these conditions, the wall-jet electrode behaves virtually as a thin-layer cell (if the nozzle spacing is small and the nozzle acts as a point source). Both detectors were concluded to yield output currents of... 

The upward bias is inherent in a technological approach to traffic safety. The rigid approach caused problems in measuring the contribution of vehicle safety regulation export and it causes problems for evaluating mandatory passive restraints ex ante. The individual net benefit approach is a better approach because it incorporates zero risk compensation as a special case and permits attempts to measure any risk compensation. 

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