Null-result measurement

The scenario, at first glance, seems to escape the standard experimental approach, namely comparison of the outcome from a set of observations with predictions based on a fittable model The control of all degrees of freedom of a quantum object is hard to achieve. Moreover, any measurement requires the interaction of quantum object and classical meter, and the object is supposed to suffer intolerable back action. However, there is a loophole based on "indirect null-result" measurements [10]. Fortunately enough, there are predictions, stated more than half a century ago, that may be matched with the results of measurements on a well-isolated and available type of microphysical system. A very counterintuitive prediction proclaims The evolution of a measured quantum system becomes slowed down, or, in the extreme, even completely frustrated [11,12]. This prediction, the "quantum Zeno effect" (QZE) [13], has evoked a wealth of theoretical work [14] but very little, and highly controversial experimental evidence. 

In a null comparison measurement of resistance, the effect of an unknown resistance must be compared with the effect of a variable standard resistance under conditions as identical as possible. Therefore, the unknown and standard resistances are placed in identical circuits in such a way that the resulting voltage or current in each circuit can be compared. Then the standard is varied until the difference in voltage or current between the two circuits is zero. Several methods for performing this comparison have been devised, of which the Wheatstone bridge is by far the most common. Comparison methods for resis-... 

One way to understand special relativity is to see how time dilation and Lorentz contraction of objects parallel to motion can be used to explain the null results of the Michelson-Morley [1] experiment, which was performed to measure the velocity of earth in relation to an assumed ether. The result was that the expected influence of such an ether on the velocity of light was not found. Let us now study this double-pass example, where one arm of a Michelson interferometer was perpendicular to the velocity of the earth s surface, while the other... 

Michelson and Morley [50] used an interferometer to measure the speed of light along two orthogonal directions parallel and perpendicular to the earth s orbital speed. They found that the speeds differed by a value somewhere in the range between 5 and 7.5 km/s. Michelson and Morley were extremely surprised because they expected to observe a difference of 30 km/s. At that time they had no plausible explanation for their empirical observation and decided to interpret the outcome of the experiment as a null result no difference in speed along both direction (apparently, the reason for this choice was that Fresnel s theory predicted no difference). 

Detector quality control records are reviewed to assure that control samples and the radiation background have been measured recently and that the detectors in use are within control limits (Section 11.2.10). Brief control source and background measurements are performed before the screening process begins to assure that detectors continue to operate appropriately and have not been contaminated recently. The detection limit in terms of activity per sample is calculated for all radionuclides of interest to determine whether a null result will meet radionuclide detection requirements for the submitted samples. 

The obstruction of the ion s evolution was said comprehensible, at least in principle, in terms of physical reaction of the apparatus on the ion ensemble, and as such not being too surprising. Only the non-local correlation of system and meter, and a null result of the detection, however, would exclude dynamical coupling and qualify as back-action-free measurement. Such a procedure would prove the obstruction of the evolution by measurement, that is, by gain of information, and would establish a real QZE, or "quantum Zeno paradox" (QZP) [21]. 

The ZEBRA-8 series of null-zone measurements featured a different neutron spectrum for each assembly. The series covers a range of spectra both harder and softer than that of the LMFBR and also emphasizes different structural/ diluent materials. The experimental data base was ideal for validating the cross-section processing technique because the experimental results had been reduced to simulating the infinite medium, and uncertainties in the extrapolation have been included. The homogeneous compositions for each assembly are shown in Table I. 

The result (only with not null importance measurements) for the criticality of power system and heat system are presented in Figure 8 and Figure 9. 

There are two procedures for doing this. The first makes use of a metal probe coated with an emitter such as polonium or Am (around 1 mCi) and placed above the surface. The resulting air ionization makes the gap between the probe and the liquid sufficiently conducting that the potential difference can be measured by means of a high-impedance dc voltmeter that serves as a null indicator in a standard potentiometer circuit. A submerged reference electrode may be a silver-silver chloride electrode. One generally compares the potential of the film-covered surface with that of the film-free one [83, 84]. 

Suppose we have two methods of preparing some product and we wish to see which treatment is best. When there are only two treatments, then the sampling analysis discussed in the section Two-Population Test of Hypothesis for Means can be used to deduce if the means of the two treatments differ significantly. When there are more treatments, the analysis is more detailed. Suppose the experimental results are arranged as shown in the table several measurements for each treatment. The goal is to see if the treatments differ significantly from each other that is, whether their means are different when the samples have the same variance. The hypothesis is that the treatments are all the same, and the null hypothesis is that they are different. The statistical validity of the hypothesis is determined by an analysis of variance. 

The records required are only for formal calibrations and verification and not for instances of self-calibration or zeroing using null adjustment mechanisms. While calibration usually involves some adjustment to the device, non-adjustable devices are often verified rather than calibrated. However, as was discussed previously, it is not strictly correct to regard all calibration as involving some adjustment. Slip gages and surface tables are calibrated but not adjusted. An error record is produced to enable users to determine the uncertainty of measurement in a particular range or location and compensate for the inaccuracies when recording the results. 

Another way to measure the Vhi is by means of photovoltaic measurements [97, 113. The technique is based on the fact that, at near zero applied bias, the OLED acts as a photovoltaic cell, where photogencraled carriers drift under the influence of Vhi to produce a current in an external cireuit. In a way similar to electroabsorption, an external bias is applied in order to compensate the built-in potential and null the net pholocurrent (Fig. 13-6). However, it has been shown that the measurement produces accurate results only at low temperatures, where diffusive transport of charges that are phoiogcneraled at the interlaces is negligible [97]. 

Given that the measured content for a certain product has been within 2% of the theoretical amount over the past, say, 12 batches, the expectation of a further result conforming with previous ones constitutes the so-called null hypothesis, Hq, i.e. no deviation is said to be observed. 

Figure 1.22. The null and the alternate hypotheses Hq resp. Hi. The normal distribution probability curves show the expected spread of results. Since the alternate distribution ND(/tb, a might be shifted toward higher or lower values, two alternative hypotheses Hi and H are given. Compare with program HYPOTHESIS. Measurement B is clearly larger than A, whereas S is just inside the lower CL(A).

Test Method (Narasimhan and Mah, 1987), the Modified Iterative Measurement Test (MIMT), and the Simultaneous Estimation of Gross Error Method (SEGE). In order to compare results on the same basis, the level of significance of each method is chosen such that it gives an AVTI, under null hypothesis, equal to 0.1. 

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