Positive accuracy

The force F which has to be applied to a molecular lever requires accurate knowledge of its position x if reversible work is to be perfonned. Specifying the positional accuracy as Ax, the uncertainty principle gives the energy requirement as... 

There are several techniques available for SFA to drive a sample along the normal direction and to position it to a specified site. A common feature of these techniques is to employ a multi-stage driving system of increasing sensitivity. The apparatus developed by Israelachivili s team, for example, uses a two-stage screw as the coarse and medium control, which gives positioning accuracy of 1 /rm and 1 nm. 

The situation can be improved by a range-to-track association technique. The blue line in the left part of Figure 10 shows the result of a range-velocity-to track association procedure as described in section 3.4. In this case the target can be tracked over the complete measurement time but with limited accuracy, especially in the azimuth angle. The target position accuracy is increased for short-range positions. 

Positive accuracy the ratio of true to observed positives ... 

Arrayer performance is commonly measured in terms of its positional accuracy, or resolution, and repeatability. For example, a typical manufacturer s specification may state a positional resolution (x,y) at 10 p with a repeatability of 1 p (x,y). Whaf fhis means is that the arrayer can print down a spot within 10 p of the desired position and return to within 1 p of that x,y coordinate most often. For printing down 100-p spots, such levels of resolution are easily met. However, how does this arrayer perform after printing 10,000 spots on 100 slides ... 

There is now no doubt that SN 1987A is positionally coincident with the B31 star, Sk-69 202. This has been established by astrometry with a positional accuracy of 0.1 arc sec, or less (White and Malin a,b West et al.). This star had the following parameters (Rousseau et al. 1978) ... 

Fig. 2 Positional detection and mean-square displacement (MSD). (a) The x, y-coordinates of a particle at a certain time point are derived from its diffraction limited spot by fitting a 2D-Gaussian function to its intensity profile. In this way, a positional accuracy far below the optical resolution is obtained, (b) The figure depicts a simplified scheme for the analysis of a trajectory and the corresponding plot of the time dependency of the MSD. The average of all steps within the trajectory for each time-lag At, with At = z, At = 2z,... (where z = acquisition time interval from frame to frame) gives a point in the plot of MSD = f(t). (c) The time dependence of the MSD allows the classification of several modes of motion by evaluating the best fit of the MSD plot to one of the four formulas. A linear plot indicates normal diffusion and can be described by = ADAt (D = diffusion coefficient). A quadratic dependence of on At indicates directed motion and can be fitted by = v2At2 + ADAt (v = mean velocity). An asymptotic behavior for larger At with = [1 - exp (—AA2DAt/)] indicates confined diffusion. Anomalous diffusion is indicated by a best fit with = ADAf and a < 1 (sub-diffusive)...

The standard deviation of each scanner reading has been estimated to be 0. 7 when using a scale of 0-255 units, and the positional accuracy of the instrument is claimed to be 2pm. Data from the microdensitometer are stored in binary format on magnetic tape as an array, typical dimensions being 600 x 600. Prior to analysis the data are reconverted to integer format and copied into a random-access disc file. 

A summary of the results for ABRF-96SEQ dataset B minor are shown in Table I. There were 1310 cycles assigned and 177 unassigned residues. Of the assigned residues, 1020 (77.8 %) were correct and 290 (22.1%) were incorrect. The positive accuracy was 87.6% which is average compared with previous studies (1-8). However, it must be noted that this peptide was present at only 2 pmol and was a minor component of the sample and thus did represent a challenging sequence calling exercise. 

Sample Amount Distributed Positive Accuracy Cysteine Accuracy Tryptophan Accuracy... 

Three-dimensional positioning of the scanner is obtained by placing three piezoelectric tubes in an orthogonal arrangement as shown in the illustration of the STM structure (Figure 5.2). The positioning accuracy of the scanner is determined by the characteristics of piezoelectric... 

Since the adhesives only crosslink at specific wavelengths, the parts to be joined can be premounted and fixed with a high degree of positional accuracy under normal workplace conditions. Quality control can also be realized (proof of adhesive application, positional correction) without affecting the adhesion of the bond. 

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