Defect structures in cosputtered thin films of transition-metal disilicides with C11<Subscript><Emphasis Type="Italic">b</Emphasis></Subscript>, C40 and C54 structures

Defect structures in crystallites of the stable phases in thin films of transition-metal (TM) disilicides (C11 _b MoSi₂, C40 TaSi₂, and C54 TiSi₂) produced by cosputtering and subsequent annealing have been investigated by transmission electron microscopy (TEM). Crystallites in thin films of MoSi₂, TaSi₂, and TiSi₂ all contain planar faults parallel to hexagonally arranged TMSi₂ planes, which are a characteristic feature commonly observed in all three crystal structures. These planar faults are twin boundaries in all cases. Twins in thin films of these disilicides, thus, have a common characteristic that the twin habit plane is parallel to hexagonally arranged TMSi₂ stoichiometric planes. For twins in thin films of C11 _b MoSi₂, and C54 TiSi₂, the twining elements can be deduced and the twin habit plane is found not to be parallel to the twinning (K ₁) plane, but to be perpendicular to it. Twins formed in C40 TaSi₂ thin films are different from those formed in C11 _b MoSi₂ and C54 TiSi₂ thin films, in that the crystal orientation of the twin is exactly the same as that of the matrix, since they are racemic twins that are only enantiomorphically (space groups of P6₂22 or P6₄22) related to each other. This article is based on a presentation in the symposium “Terence E. Mitchell Symposium on the Magic of Materials: Structures and Properties” from the TMS Annual Meeting in San Diego, CA in March 2003.     

System design of “Ba”-like stages for improvisational acts via Leibnizian space–time and Peirce’s existential graph concepts

A framework for “improvisational” social acts and communication is introduced by referring to the idea of “relationalism” such as natural farming, permaculture and deep ecology. Based on this conception, the notion of Existential Graph by C. S. Peirce is introduced. The notion of extended self in deep ecology is substantiated based on the Roy Adaptation Model in Nursing Theory and Narrative approaches. By focusing on Leibnizian notions of space and time and by introducing Petri net, a spatio-temporal model of improvisation is constructed. This model is expected to substantiate the interesting notion of “Ba” proposed by H. Shimizu reflecting Japanese culture.     

Two-dimensional pattern matching by two-dimensional on-line tessellation acceptors

By reducing an array matching problem to a string matching problem in a natural way, it is shown that efficient string matching algorithms may be applied to arrays. In this paper, based on the ideas due to Baker, an application of the two-dimensional on-line tessellation acceptor (2-dota) is presented for very rapid on-line detection of occurrences of a fixed set of keyarrays as embedded subarrays in a text array. The main part of the algorithm described in this paper consists of constructing two finite state pattern (string) matching machines from the keyarrays. By combining these two finite state pattern matching machines, we construct the 2-dota which, given an m × n text array, solves the two-dimensional pattern matching problem in m + n?1 steps.     

A note on closure properties of the classes of sets accepted by tape-bounded two-dimensional turing machines

For the classes of sets accepted by several tape-bounded two-dimensional Turing machines, we examine closure properties concerning the operations of taking row catenation, column catenation, row closure, column closure, and projection.     

Cyclic closure properties of automata on a two-dimensional tape

In this paper, we investigate cyclic closure properties of several types of automata on a two-dimensional tape. It is shown that (1) the classes of sets accepted by two-dimensional finite automata, deterministic one-way parallel/sequential array automata, and two-dimensional deterministic on-line tessellation acceptors are not closed under row or column cyclic closure, and (2) the class of sets accepted by two-way parallel-sequential array automata is not closed under row cyclic closure.     

Development and characterization of an aerosol time-of-flight mass spectrometer with increased detection efficiency

This paper describes the development and characterization studies of a more efficient aerosol time-of-flight mass spectrometer (ATOFMS), showing results for the on-line detection and determination of the size and chemical composition of single fine (100-300 nm) and ultrafine (<100 nm) particles. An aerodynamic lens inlet was implemented, replacing the converging nozzle inlet used on conventional ATOFMS instruments. In addition, the light scattering region was modified to enhance the scattering signals for smaller particles. Polystyrene latex spheres (PSL) with aerodynamic diameters ranging from 95 to 290 nm were used to characterize the particle sizing efficiency (product of particle transmission efficiency and particle scattering efficiency), particle detection efficiency (product of particle sizing efficiency and particle hit rate), and particle beam profile and perform instrument calibration. At number concentrations of <20 particles/cm(3), the particle sizing efficiencies were determined to be approximately 0.5% for 95 nm and approximately 47% for 290-nm PSL particles, while the particle detection efficiencies were measured to be approximately 0.3% for 95 nm and 44% for 290-nm PSL particles. This represents a significant increase (i.e., at least 3 orders of magnitude) in detection efficiencies for smaller particles over the conventional ATOFMS. In addition, the beam profiles for PSL particles of various sizes were measured in the ion source of the mass spectrometer and follow a Gaussian distribution with a full width at half-maximum of approximately 0.35 mm. The resulting higher detection efficiencies allow ATOFMS to obtain higher temporal resolution measurements of the composition of fine and ultrafine individual particles as demonstrated in initial ambient measurements in La Jolla, CA. At typical ambient particle number concentrations of 10(2)-10(3) particles/cm(3), approximately 30 000 particles with aerodynamic diameters of <300 nm were detected with average 24-h hit rates of 30% for particles between 50 and 300 nm. This advancement, allowing for high temporal resolution measurements of the composition of smaller particles with higher efficiency, adds to a growing number of instruments that can chemically characterize individual fine and ultrafine particles, with the goal of providing new insights into a number of areas including environmental and material sciences, health effects studies, industrial hygiene, and national security.     

A spherical code and stress tensor inversion

A spherical code is a set of many points arranged at more or less uniform intervals on a hypersphere. Here, we present a spherical code comprising 60,000 points in five-dimensional space and the list of the uniformly distributed reduced stress tensors corresponding to the points. This code benefits tectonic studies. By the way of example, it is demonstrated how the code improves the resolution of stress tensor inversion.     

Lattice Boltzmann simulation on continuously regenerating diesel filter

To reduce particulate matter (PM) including soot in diesel exhaust gas, a diesel particulate filter (DPF) has been developed. Since it is difficult to observe the phenomena in a DPF experimentally, we have conducted a lattice Boltzmann simulation. In this study, we simulated the flow in a metallic filter. An X-ray computed tomography (CT) technique was applied to obtain its inner structure. The processes of soot deposition and oxidation were included for a continuously regenerating diesel filter. By comparing experimental data, a parameter of soot deposition probability in the numerical model was determined.     

Predictive value of vascular endothelial growth factor (VEGF) in metastasis and prognosis of human colorectal cancer

Vascular endothelial growth factor (VEGF) may affect the phenotype of cancer cells, such as growth velocity and metastatic potential, due to its probable multifunctional property including a mitogenic activity for vascular endothelial cells. The present study was designed to investigate the association of VEGF mRNA expression with progression and metastasis of human colorectal cancer. The level of VEGF mRNA expression was quantified by Northern blot hybridization in tumorous and non-tumorous tissues obtained from 60 primary colorectal cancer patients. The ratio of the former to the latter was defined as the VEGF T/N ratio, and the prognostic significance of this ratio, following surgery, in addition to the relationship to progression and metastatic potential, was evaluated. The value of the VEGF T/N ratio was significantly correlated with the depth of tumour infiltration (P=0.046), the incidence of liver metastasis (P < 0.0001) and lymph node metastasis (P=0.036). Patient prognosis was estimated by the Kaplan-Meier method and the log-rank test. When the VEGF T/N ratio was higher than 4.8 for which the chi2 value of the log-rank test was maximal, the tumour was defined as showing overexpression of VEGF mRNA. Patients with overexpression of VEGF mRNA demonstrated poorer survival than patients without overexpression of VEGF mRNA (P < 0.001). The overall estimated hazard ratio for death in patients with overexpression of VEGF mRNA was 1.94 according to a multivariate analysis (P=0.005). Thus, VEGF is associated with the progression, invasion and metastasis of colorectal cancer, and overexpression of VEGF mRNA in the primary tumour is assumed to be closely correlated with poor prognosis in colorectal cancer patients. Moreover, the VEGF T/N ratio may be used as an independent prognostic marker in colorectal cancer patients.