In three experiments, using a two-alternative forced-choice task, we obtained depth judgments of displays containing transparent regions. The regions varied in lightness, size, and animation. Observers nearly always strongly preferred one certain depth ordering among the regions, even though their lightness conditions were expected to give rise to ambiguity among possible orderings. This expectation was based on the contrast polarity model, which expects ambiguity in the absence of contrast polarity reversal. The expectation was founded also on a stronger condition based on the transmittance anchoring principle, which gives preference to the largest lightness contrast between regions. In the absence of contrast polarity reversal and in conditions of balanced regional contrast, preferences were shown to depend on additional conditions of contrast between two respective regions and their overlap. Depth ordering judgment seems to be based on a critical decision threshold, independently of the coordinate system used to specify lightness. We also investigated the role of non-photometric factors such as motion and relative size, and concluded that these variables can modulate depth ordering judgments in transparency.
An experimental evidence of subwavelength imaging with a "lens", which is a uniaxial negative permittivity wire medium slab, is reported. The slab is formed by gratings of long thin parallel conducting cylinders. Taking into account the anisotropy and spatial dispersion in the wire medium we theoretically show that there are no usual plasmons that could be exited on surfaces of such a slab, and there is no resonant enhancement of evanescent fields in the slab. The experimentally observed clear improvement of the resolution in the presence of the slab is explained as filtering out the harmonics with small wavenumbers. In other words, the wire gratings (the wire medium) suppress strong traveling-mode components increasing the role of evanescent waves in the image formation. This effect can be used in near-field imaging and detection applications.
matrices are compared on the basis of the general metrological criteria of A-, D-, and E-optimality taken from the mathematical theory of experimental design and the statistical properties of the sources under study. Optimal values of the mean transmission of encoders as a function of the ratio of the statistical characteristics of the particular distribution of radiation sources under study and of the interference superimposed on the measurement are obtained.In [1] an analytic survey of multiplex measurement systems, types of codes, and types of encoders constructed on the base of cyclic (0, 1)-, (-1, 1), and (-1, 0, 1)-tables and matrices was presented. It was noted that the initial motivation for the use of these types of codes and encoders was the opportunity they afforded for reducing the measurement error produced by interference. However, it is a difficult problem to evaluate and minimize measurement errors, which may include random and systematic components caused by interference, encountered in the use of multiplex measurement systems. Even in traditional experiments, there are numerous criteria employed, for example, in the area of radiation introscopy, for the purpose of selecting detectors, collimators, measurement conditions, etc.[2]. The existence of different criteria is due especially to difficulties or even the impossibility of solving in general form the problem of minimizing the deviation of an unknown threedimensional function on the basis of an evaluation of this function obtained as a result of measurements and subsequent processing.When multiplex measurement systems are employed, the systematic measurement error is largely determined by the type of encoder in use, especially when it is a matter of obtaining tomographic (focused) images of a three-dimensional object, the source of the radiation. As in the traditional experiment (i.e., without the use of multiplex measurement systems), the statistical nature of the interference superimposed on the results of measurements, together with the statistical (quantum) nature of the particular types of measured quantities under study (called the "statistics of effect'), are determined. However, when multiplex measurement systems are employed, the expressions for the calculations and properties of the random errors are substantially different from what is encountered in the traditional experiment. In the case of multiplex measurement systems, the target of the optimization process may be selection of the type of encoder as well as selection of its mean transmission p, which is equal, for example, to the number of open cells of a collimator (pinholes) k divided by the total number of cells v (o = k/v), which, for a fixed value of v, is equivalent to optimization of k. The systematic component of the measurement error will be analyzed in the discussion which follows. In the present study, the random component of the measurement error and the possibility of minimizing this component of the error in the application of'multiplex measurement systems will be...
The concentrations of 109Cd in fallout and in surface air at observation points in the Soviet Union during 1964–1967 are summarized. Analysis of these data and their comparison with results from experiments on 102Rh suggest that the mean residence time of finely divided aerosols in the atmosphere above 21 km from sources above 100 km is 14 years. Analysis of the 238Pu fallout data indicates that the mean residence time of aerosols injected at about 40–60 km altitude is significantly lower, possibly about 4 years.
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