Bubbles, seeds, stones, and striae can be detected by illuminating the sample with a bright light and observing the scattered light. The use of a shadow graph or Foucault knife-edge (Schlieren) is very useful in detecting internal defects. In the Schlieren test, shown in Fig. 2-1, the irregularities become visible since they deviate light past the stop. If the surfaces are not polished, they ma...

Thresholds for the discrimination of orientation were measured in the human fovea for figures and borders delineated by solid lines and by "pacman" tokens as introduced by Kanizsa, as well as by contours induced by monocular tokens giving a stereoscopic depth illusion of a knife edge. Orientation discrimination of these illusory contours is poorer by a factor of approximately 2 than that of equ...

Shearing stress of wheat stalk was measured for four moisture content levels (15, 25, 35 and 45%, w.b.), three cutting heights (100, 200 and 300 mm), two types of cutting knives, smooth and serrated edge and three blades oblique angle (0, 15 and 30 deg.). The results of data analysis showed that the shearing stress of wheat stems decreased as the moisture content decreased. The shearing force o...

A Langmuir monolayer trough that is equipped for simultaneous microrheology and standard rheology measurements has been constructed. The central elements are the trough itself with a full range of optical tools accessing the air-water interface from below the trough and a portable knife-edge torsion pendulum that can access the interface from above. The ability to simultaneously measure the mec...

We propose a new nonparametric test of affiliation, a strong form of positive dependence with independence as a special, knife–edge, case. The test is consistent against all departures from the null of affiliation, and its null distribution is standard normal. Like most nonparametric tests, a sample–size dependent input parameter is needed. We provide an informal procedure for choosing the inpu...

Circular and linear zone plates have been fabricated on the surface of silicon crystals for the energy of 8 keV by electron beam lithography and deep ion plasma etching methods. Various variants of compound zone plates with first, second, third diffraction orders have been made. The zone relief height is about 10 mkm, the outermost zone width of the zone plate is 0.4 mkm. The experimental testi...

Accurate microvascular morphometric information has significant implications in several fields, including the quantification of angiogenesis in cancer research, understanding the immune response for neural prosthetics, and predicting the nature of blood flow as it relates to stroke. We report imaging of the whole mouse brain microvascular system at resolutions sufficient to perform accurate mor...

The importance of primary elections is considered within the context of U.S. Senate elections where senators serve overlapping terms and voters are assumed to balance their two senators against each other. Voters behave strategically in the primaries but convergence to the median position is not achieved except as a knife-edge result. More generally, constraints in the party space prevent the p...

The pyramid wavefront sensor is very similar to the Fourier knife-edge test, but employs dynamic modulation to quantify the phase derivative. For circular modulation, we compare approximate geometrical optics calculations, more exact diffraction calculations, and experimental results. We show that both the sinusoidal and the approximate linear relationship between wavefront derivative and wavef...