Interactive image segmentation based on level sets of probabilities

In this paper, we present a robust and accurate algorithm for interactive image segmentation. The level set method is clearly advantageous for image objects with a complex topology and fragmented appearance. Our method integrates discriminative classification models and distance transforms with the level set method to avoid local minima and better snap to true object boundaries. The level set function approximates a transformed version of pixelwise posterior probabilities of being part of a target object. The evolution of its zero level set is driven by three force terms, region force, edge field force, and curvature force. These forces are based on a probabilistic classifier and an unsigned distance transform of salient edges. We further propose a technique that improves the performance of both the probabilistic classifier and the level set method over multiple passes. It makes the final object segmentation less sensitive to user interactions. Experiments and comparisons demonstrate the effectiveness of our method.     

Automated identification of vessel contours in coronary arteriograms by an adaptive tracking algorithm

A tracking algorithm for identification of vessel contours in digital coronary arteriograms was developed and validated. Given an initial start-of-search point, the tracking process was fully automated by utilizing the spatial continuity of the vessel's centerline, orientation, diameter, and density. The incremental sections along a major vessel were sequentially identified, based on the assumptions of geometric similarity and continuation between adjacent incremental sections. The algorithm consisted of an extrapolation-update process which was guided by a matched filter. The filter parameters were adapted to the measured lumen width. The tracking process was robust and extremely efficient as indicated by test results on synthetic images, digital subtraction angiograms, and cineangiograms. The algorithm provided accurate measurement of lumen width and percent stenosis that was relatively invariant to the vessel's orientation, dynamic range, background variation, and degree of blurring     

An acoustic micrometer and its application to layer thickness measurements

The principle and system of the acoustic micrometer are described. Its basic performance, with respect to the stability, accuracy, spatial resolution, and temperature dependence, is also discussed. Gold layers electroplated on substrates of 42% Ni-Fe alloy were taken as test specimens in the present study. The measurable range of the thickness for gold layers covered from 1 to 20 mum when a frequency range of 10-200 MHz was used. Stability and accuracy were achieved to within +/-0.2% and +/-1%, respectively.     

Excitation of plate waves in thickness measurements of layers deposited on thin plates

Layer thickness measurements with an acoustic micrometer using pseudo-Sezawa waves in which ultrasonic waves are obliquely applied to a layered surface of a specimen have been proposed. A case in which the plate thickness of the specimen is so thin that it cannot be regarded as a half space is studied. A number of modes of plate waves are then excited in addition to pseudo-Sezawa waves. The plate waves, giving rise to the appearance of extra dips in the power spectrum of reflected waves, cause difficulties in the measurements. To prevent the excitation of plate waves, it is proposed that a mask of a sound-insulating material with a slit aperture should be placed on the layered surface of the specimen. Experiments and theoretical calculations, using lead frames of LSI chips as typical test specimens with thin substrates, were performed to demonstrate the effectiveness of the present method in preventing the excitation of plate waves.     

Pressure-induced conversion of α-connectin to β-connectin

The mechanism of the pressure-induced tenderization of meat has not been fully established in spite of its beneficial effect. To detect the changes in the large structural proteins of the myofibrils induced by pressurization without heat treatment, high hydrostatic pressure (100-300 MPa) was applied to rabbit at-death skeletal muscle for 10 min at low temperature (0-2°C). Significant differences in the electrophoretic pattern of connectin (also called titin) in isolated myofibrils were observed between the control and pressurized muscle samples. The conversion of α-connectin (2800 kDa) to β-connectin (2100 kDa) was accelerated with increasing pressure applied to the muscle; also nebulin (800 kDa) was degraded by pressure treatment. From the results it is clear that the degradation of connectin is induced by pressurization alone without heat treatment. If the conversion of α-connectin to β-connectin during conditioning has some influence on meat tenderization, the pressure-induced conversion of α- to β-connectin is possibly one of the causes of pressure-induced tenderization of meat.     

Heme pigment content in meat as affected by the addition of curing agents

The effects of curing agents on the content of heme pigments (HP) in meat were examined. Minced porcine skeletal muscle was treated with NaCl, NaNO(2) and sodium ascorbate (NaAsA), separately or in combination, and stored at 2-3°C for 7 days. HP content decreased with increase in NaCl concentration and the decrease was about 50% and 80% at NaCl concentrations of 2% and 10%, respectively. Two percent NaCl prevented HP destruction, when previously mixed with 100 ppm NaNO(2) or 0·1% NaAsA. Although some decrease in HP content was noted following application of a mixture of NaCl, NaNO(2) and NaAsA, it was essentially the same as that of the control during 7 days of refrigerated storage. In a model solution containing the same curing agents as those applied to the meat. NaCl had no effect and myoglobin (Mb) content remained constant during storage. From the present results, endogenous muscle constituents appear to act in concert with NaCl to bring about a decrease in HP content.     

On the merits of ancient Chinese eye acupressure practices

Chinese schoolchildren and adults with strenuous visual tasks routinely perform massage-and-pressure exercises on selected acupressure points around the eyes. This practice, taught by the Jing-Luo school of acupuncture for more than 4000 years, is claimed to prevent and cure myopia and other afflictions thought to result from visual close work. A four-week pilot experiment was carried out with the aim of designing a proper study on the possible short-term benefits of eye acupressure programmes. Questionnaire data revealed that the subjects did experience various eye/vision symptoms as a result of the 90 min experimental task. This could not be verified by the measurements of accommodation precision and critical flicker fusion, nor could any beneficial effects of acupressure be seen over the four experimental weeks.     

Laser spectroscopic measurement of quenching and doublet mixing rates of the Na(3P(3/2, 1/2)) doublet in a propane-air flame

We have measured the quenching rate of the Na 3P level and the doublet mixing rates of the Na 3P(3/2) and 3P(1/2) levels in a propane-air flame at atmospheric pressure. To obtain these rates, subnanosecond time-resolved fluorescence measurements were made using a mode-locked dye laser and the time-correlated single-photon counting method. Our results are 1.4 x 10(9) s(-1) for the quenching rate and 3.0 x 10(9) s(-1) for the 3P(3/2) --> 3P(1/2) mixing rate.