Clinical planning support system-CliPSS

Clinical planning support system (CliPSS), which is software developed to support neurosurgical planning and to enable a surgeon to generate 3-D computed images interactively and simulate sterotactic surgery on them, is discussed. The basic functions of CliPSS, involving section display, editing, extraction, and rendering, are reviewed. A method of thinning the volume of polygonal data for a surface-rendered image, which improves CliPPS's performance and interactivity, is presented     

Specific isoprenyl group linked to transducin gamma-subunit is a determinant of its unique signaling properties among G-proteins

Among 11 subtypes of heterotrimeric G-protein gamma-subunit, gamma1 (rod), gamma8 (cone) and gamma11 are modified with farnesyl while the others are modified with geranylgeranyl at the C-terminus. To understand the role of specific isoprenylation (farnesylation) of retinal transducin, we examined how and to what extent the type of isoprenyl group affects transducin-beta gamma (beta1 gamma1) functions such as interactions with membranes, Galpha/receptor, and effectors. To this end, the C-terminal farnesylation signal sequence (CVIS) of gamma1 was replaced by a geranylgeranylation signal (CVIL), and the resultant mutant (S74L) or wild-type (WT) gamma1 was coexpressed with beta1 in the baculovirus-Tn5 insect cell system. Both gamma1WT and gamma1S74L expressed as a beta gamma complex were mixtures modified with farnesyl and geranylgeranyl groups. The ratio of farnesyl to geranylgeranyl in preparations of beta1 gamma1WT and beta1 gamma1S74L purified from the Tn5 cell membrane fraction was about 1:2 and 1:6, respectively. These two forms of recombinant beta1 gamma1 and retinal beta1 gamma1 were different in their abilities to associate with rod outer segment membranes with the following rank order: beta1 gamma1S74L > beta1 gamma1WT > retinal beta1 gamma1. Functionally, beta1 gamma1S74L was the most potent to promote pertussis toxin-catalyzed ADP ribosylation of transducin-alpha (Talpha), to stimulate metarhodopsin II-catalyzed GTPgammaS-binding reaction to Talpha and to modulate adenylyl cyclase and phospholipase C activities. All of the beta1 gamma1 functions absolutely required the isoprenylation of the gamma-subunit. As for the interaction with Goalpha and adenylyl cyclase, predominantly geranylgeranylated beta1 gamma1S74L was less effective than geranylgeranylated beta1 gamma2 purified from bovine brain. These results demonstrate that the properties of Gbeta gamma are strongly affected by the type of functionally indispensable isoprenylation in addition to the amino acid sequence of Ggamma. The relative contribution of the two factors depends on proteins with which Gbeta gamma interacts.     

Mechanisms of tubulin modification by phosphatidylcholine hydroperoxides

The interaction of lipid peroxides with cellular proteins has been postulated to contribute to cellular aging. A potential target for such effects is tubulin, the building block of microtubules. We examined the concentration-dependent effects of phosphatidylcholine hydroperoxides on the ability of tubulin to polymerize into microtubules. The results demonstrated that even very low concentrations of peroxides were sufficient to interfere with the tubulin and, therefore, the microtubule function. Decreased tubulin activity (as measured by tubulin GTPase activity) showed correlation with the modification of methionine and cysteine in tubulin and a change in the tubulin conformational state as indicated by fluorescence and ultraviolet spectroscopic measurements. As no effect on electric conductivity was observed, indicating that modulation of ionic binding was not involved, the interaction mechanism may be a hydrophobic one.     

Field-induced silver injection into lithium disilicate glass

The objective of this work was to study field-induced silver injection into Li₂O · 2SiO₂ glass by the techniques of secondary ion mass spectrometry and thermally stimulated polarization/depolarization current (TSPC/TSDC), with an emphasis on the comparison experiments between gold and silver electrodes. For both anode materials, accumulation of lithium was found near the cathode. The blocking nature of the gold anode was demonstrated by the closeness of the observed and estimated width of the alkali-depleted region near the anode. For silver-anode samples, field-induced silver injection as well as lithium conduction occured and increased the TSPC slope from that of the gold-anode samples.     

A Spatial-Domain Technique for the Design of 3-D Separable-Denominator State-Space Digital Filters

In this paper,a technique for designing 3-D separable-denominator state-spacedigital filters is developed. The design process is divided intotwo phases. First, the coefficient matrices related to stabilityare constructed for the filter to be stable by using alternatingvariable method. Next, the other matrices are obtained by solvinglinear equations. These phases are repeated until there is nosignificant change in the squared error function.     

Complex impedance and admittance of a silver-conducting glass

From the analysis of complex impedance and admittance data of (Agl)₇₅(Ag₄P₂O₇)₂₅ glass, an Ag⁺-ion conductor, it was revealed that the sample can be approximated by a seriesRC ₁ circuit at high temperature, with the capacitorC ₁ arising from the charge-carrier depleted region near the anode which develops as conduction proceeds, and by a parallelRC ₂ circuit at low temperature, with the capacitorC ₂ arising from the saturated value for ionic polarization of, say, the silver-iodine pairs as well as from the relaxation effect of the Ag⁺ ions for conduction. TheC ₁ andC ₂ values were found to be almost temperature-independent at peak frequencies of the distorted semicircles in respective complex planes, with the ratioC ₁/C ₂ as large as 10⁴.     

The black layer underneath the anode of dc-biased silver metaphosphate glass

The black layer was generated underneath the anode when a gold-electroded silver metaphosphate glass, a silver-ion conductor, was dc biased with 500 V/cm or 250 V/cm at 140°C . It was concluded that this layer corresponded to the silver-depleted region formed by conduction of the silver ions towards the cathode. The blackening was ascribed to be due to the shortened Ag-O distance, caused by structural rearrangement within the region into the P₂O₅-like structure on biasing.     

Effects of light guides and optical filters for a high density lead glass counter

Effects of various light guides on energy resolution, position dependence of the output pulse and the hadron suppression factor were studied for a high density lead glass counter with particles of energies between 1 GeV and 16 GeV. The best hadron suppression factor was obtained for a configuration with a plastic light guide and a short wave cutoff filter at little expense to energy resolution. The energy resolution is worse at high energy and is dependent on the hit position of an incident particle for a BK7 light guide.     

Titanium-aluminum oxynitride (TAON) as high-k gate dielectric for sub-32 nm CMOS technology

High-k insulators for the next generation (sub-32 nm CMOS (complementary metal-oxide-semiconductor) technology), such as titanium-aluminum oxynitride (TAON) and titanium-aluminum oxide (TAO), have been obtained by Ti/Al e-beam evaporation, with additional electron cyclotron resonance (ECR) plasma oxynitridation and oxidation on Si substrates, respectively. Physical thickness values between 5.7 and 6.3 nm were determined by ellipsometry. These films were used as gate insulators in MOS capacitors fabricated with Al electrodes, and they were used to obtain capacitance-voltage (C-V) measurements. A relative dielectric constant of 3.9 was adopted to extract the equivalent oxide thickness (EOT) of films from C-V curves under strong accumulation condition, resulting in values between 1.5 and 1.1 nm, and effective charge densities of about 10¹¹ cm⁻². Because of these results, nMOSFETs with Al gate electrode and TAON gate dielectric were fabricated and characterized by current-voltage (I-V) curves. From these nMOSFETs electrical characteristics, a sub-threshold slope of 80 mV/dec and an EOT of 0.87 nm were obtained. These results indicate that the obtained TAON film is a suitable gate insulator for the next generation (MOS) devices.