Computerized detection of pulmonary embolism in spiral CT angiography based on volumetric image analysis

A fully automated method for computerized detection of pulmonary embolism in spiral computed tomography angiography was developed based on volumetric image analysis. The detection method is based on segmentation of pulmonary vessels to limit the search space, and analysis of several three-dimensional features inside segmented vessel volume. The features utilized are vascular size, local contrast based on mathematical morphology, degree of curvilinearity based on second derivatives, and geometric features such as volume and length. Detection results were obtained for 19 clinical data sets and the performance of the method was evaluated. Using the number and locations of thrombi diagnosed by radiologists as the gold standard, 100% sensitivity was achieved with 7.7 false positives per case, and 85% sensitivity was obtained with 2.6 false positives. For identification of all the positive cases as positive, i.e., detection of at least one thrombus per positive case, 1.9 false positives per case were obtained. These preliminary results suggest that the method has potential for fully automated detection of pulmonary embolism.     

Quantitative analysis of double-stranded DNA amplified by a polymerase chain reaction employing surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) was utilized for the quantitative analysis of double-stranded (ds) DNA amplified by a polymerase chain reaction (PCR). 4?, 6-Diamidino-2-phenylindole dihydrochloride (DAPI), which intercalates into ds-DNA but does not form a complex with single-stranded (ss) DNA, was added to a DNA solution after amplification by PCR. When the solution was mixed, including ds-DNA-DAPI complexes and free DAPI with silver colloid sol, only free DAPI was adsorbed on the colloid surface. The dye on the colloid gave very intense SERS signals with excitation at 514.5 nm, whereas DAPI engaging in the intercalation with ds-DNA did not show any SERS signal. The SERS spectrum of DAPI on the colloid showed a strong band at 1610 cm(-1) due to the C?N stretching mode, and a linear relationship was observed between the peak intensity of the C?N stretching band and the concentration of free DAPI. Therefore one can determine the concentration of free DAPI by the SERS measurement. The more ds-DNA there is in the solution, the less free DAPI there is. Thus it is possible to quantitatively analyze the ds-DNA amplified by PCR indirectly by using SERS. The correlation coefficient between the peak intensity of the C?N stretching band and the concentration of ds-DNA amplified by PCR was calculated to be 0.988 for a concentration range from 0.1 to 1.3 mg/ml.     

Influence of aging heat treatment on mechanical properties of biomedical Ti–Zr based ternary alloys containing niobium

Titanium–zirconium based alloys containing a small amount of niobium were investigated in order to evaluate their possible use as biomedical materials. Zirconium, which belongs to the IVa group, is known to have good corrosion resistance and biocompatibility similar to titanium. As the titanium–zirconium system shows a complete solid solution, a wide variation of alloy design is available and large quantities of solid-solution hardening must be possible. Niobium, having a -phase stabilizing effect, was chosen as a ternary element in order to control desirably the microstructure. There have been no reports which suggest its harm to a living body. The alloys containing 2% or 3% niobium showed the highest hardness value after aging heat treatment at 773 K. In contrast to this, no alteration of hardness was seen in specimens aged at 1073 K. Through conventional X-ray diffractometry and in situ X-ray analysis using a hot stage, -phase precipitation in the A matrix was identified. From the above results, it is concluded that alloys containing 2%–3% niobium are hopeful candidates for new kinds of biomedical alloys, when they are heat treated under suitable conditions. © 1998 Kluwer Academic Publishers     

Continuous measurements of bronchial exposure induced by radon decay products during inhalation

The deposition of radon decay products is not equal in each of the respiratory regions and as the presence of radon has been linked with an increase in lung cancer risk, it is important to calculate the deposition of radon decay products in each of the respiratory regions. Recently, many studies on the deposition of radon in respiratory regions have been simulated using wire screens. The systems and equipment used in those studies are not suitable for field measurements as their dimensions are relatively massive, nor can they measure continuously. We developed a continuous bronchial dosimeter (CBD) which is suitable for field measurements. It was designed with specifications that allow it to be remain compact. The CBD simulates the deposition of radon decay products in the different respiratory regions by the use of a combination of wire screens. Deposition in the simulated regions of the lung can be continuously estimated in various environments. The ratio of activities deposited in a simulated nasal cavity (N) and tracheobronchial (TB) regions was calculated from the results of simultaneous measurements using CBD-R (reference), CBD-N (nasal), and CBD-TB (tracheobronchial) measurement units. After aerosols were injected into the radon chamber, the ratio of N and TB depositions decreased. This results indicate that the CBD gave a good response to changes in the environment. It was found that the ratio of N and TB deposition also varied with time in each actual environment.     

Quadruped walking robots at Tokyo Institute of Technology

I(Hirose) was walking along a mountain path near Mt. Fuji on a summer day of 1976, when I found a daddy long-legs walking on the ground. I picked it up in my palm and allowed it to walk over my fingers, and the bug walked effortlessly even over finger-made obstacles ten times larger than its own body. While I was watching the motion of the bug, I started to have the desire to make bigger multilegged walking robots, which can walk over large buildings. This was the beginning of our study of walking robots, which was to last for more than 30 years.     

Modulatory role of protein tyrosine kinase activation in the receptor-induced contractions of the bovine cerebral artery

Changes in contractile force were measured during isometric contraction of the bovine middle cerebral artery caused by stimulation of various receptors and by application of high K+, caffeine, and protein kinase C (PKC)-activators. The protein tyrosine kinase (PTK)-inhibitors, such as genistein and tyrphostin, were applied before testing the effect on the contractions or during the maximal plateau of the contraction. The contractions induced by serotonin, prostaglandin F2 alpha, endothelin-1, and thromboxane A2 were significantly and dose-dependently depressed by the PTK-inhibitors (IC50 2-15 microM). In contrast, contractions were significantly augmented by 1 microM pervanadate, an inhibitor of phosphoprotein tyrosine phosphatase. Lineweaver-Burk plotting of the dose-response curves with an increase in inhibitor concentration indicated that the receptor affinity for each agonist remained unchanged in spite of marked depression of the responses. Although the effect was not significant, contractions induced by both high K+ and caffeine were also depressed slightly by PTK-inhibitors in the same range of concentrations used for receptor-induced contractions. Contractions induced by PKC-activators, such as 1-oleoyl-2-acetyl-sn-glycerol and phorbol-12,13-diacetate, were significantly depressed by PTK-inhibitors at concentrations similar to those used for receptor-induced contractions. The results suggest that receptor stimulations which produce sequential activation of phospholipase C and PKC can activate PTK and trigger the so-called "PTK-cascade" causing a sustained or long-lasting contraction similar to the cerebral vasospasm observed clinically.     

Pore size control technique in the spinning of polysulfone hollow fiber ultrafiltration membranes

Conditions for finger-like void formation in polysulfone (PS) ultrafiltration membranes were studied empirically. It was found that both the “mixability parameter” which was obtained in separate titration experiments and the viscosity of coagulants could be used to predict membrane morphology. It was also found that finger-like void layers appeared under the conditions which dope had concentrations quite apart from the phase separation area and which coagulant had both a low mixability parameter and low viscosity.

These factors proved to play a very important role in controlling the pore size of membranes. The results of this study were applied to obtaining pore size variations of PS hollow fiber membranes.     

A 2-approximation NC algorithm for connected vertex cover and tree cover

The connected vertex cover problem is a variant of the vertex cover problem, in which a vertex cover is additional required to induce a connected subgraph in a given connected graph. The problem is known to be NP-hard and to be at least as hard to approximate as the vertex cover problem is. While several 2-approximation NC algorithms are known for vertex cover, whether unweighted or weighted, no parallel algorithm with guaranteed approximation is known for connected vertex cover. Moreover, converting the existing sequential 2-approximation algorithms for connected vertex cover to parallel ones results in RNC algorithms of rather high complexity at best.In this paper we present a 2-approximation NC (and RNC) algorithm for connected vertex cover (and tree cover). The NC algorithm runs in O(log²n) time using O(Δ²(m+n)/logn) processors on an EREW-PRAM, while the RNC algorithm runs in O(logn) expected time using O(m+n) processors on a CRCW-PRAM, when a given graph has n vertices and m edges with maximum vertex degree of Δ.     

An ultrahigh‐definition display using the pixel‐offset method

Abstract— An ultrahigh‐definition display system quadrupling the horizontal and vertical resolution of HDTV has been developed. In order to obtain the ultrahigh definition, four LCD panels (red, green 1, green 2, and blue) are combined using the spatial pixel‐offset method. Therefore, only green images have an ultrahigh resolution of 4096 × 7680 pixels, while red and blue images have 2048 × 3840 pixels. The ultrahigh resolution was confirmed by subjective assessment testing. The scores of the test have the same tendencies as the SQRI values. The necessary accuracy of the convergence correction is calculated to be within 0.3 pixels by the modified s‐CIELAB method.