Applying path‐counting methods for measuring the robustness of the network‐structured system

We consider the path‐counting problem that asks how many paths exist between any two different nodes in a network after deleting an arbitrary number of edges or nodes from the original network. Using path‐counting methods, we propose a quantitative method for measuring the robustness of the network‐structured system. First we define the connectivity function and attempt to obtain the expected connectivity function for the network. Applying the Monte Carlo method, we estimate expected edge deletion and node deletion connectivity functions when an arbitrary number of edges or nodes are deleted from the original network. We attempt to approximate the expected edge deletion connectivity function using an appropriate nonlinear function with two parameters. We also show the numerical results of applying the path‐counting method with their analysis in order to quantitatively evaluate the connectivity for some special types of networks.     

NQR in La1.85Sr0.15Cu1−x Li x O4 under high pressure (1.9GPa)

Nuclear quadrupole resonance (NQR) under steady pressure (1.9GPa) was performed on La _1.85 Sr _0.15 Cu _1–x Li _x O ₄ where Li substitution causes metal (x = 0)-insulator (x = 0.5) transition. Two kinds of Cu-NQR signals corresponding to both states have been observed at the intermediate amount of x. Effect of the pressure was investigated for x = 0.25 and 0.3 samples. Possible Li-distribution pattern was proposed for the x = 0.3 sample.     

Macroscopic estimation method of the mixedness of Kenics type static mixer

We investigated the mixing process of the Kenics type static mixer, in which the mixing is enhanced by both advective mixing and mixing due to molecular diffusion in order to propose an estimation method of the mixedness. The results show that the element divides, folds and stretches the mixing fluids and forms a lamellar structure with striation width l _a . The value of l _a decreases with an increase in the number of elements by l _a -(2 ⁿ⁻¹)⁻¹, which represents the characteristics length of advective mixing. The characteristic length of mixing due to molecular diffusion l _d can be estimated by solving the one-dimensional unsteady species conservation equation analytically. The macroscopic estimation and prediction method of mixedness is proposed as function of l _a and l _d . When l _a >l _d , the advective mixing is dominant, while, when l _a <l _d , the mixing due to molecular diffusion plays an important role.     

Stabilizing control method for suppressing oscillations ofinduction motors driven by PWM inverters

A novel control method that suppresses oscillations generated when an induction motor is driven by PWM (pulse width modulated) inverters is described. The suppression is done by keeping the power direction constant throughout the period of oscillation of the negative current component of the inverter input current. This period is determined only by the frequency of the PWM signals. Because it is not affected by motor parameters, such as the number of poles or motor capacity, the gains of the regulator in the control system do not have to be adjusted, even if this method is applied to various kinds of induction motor drive systems. Experiments have proven that oscillations can be suppressed regardless of the motor type or speed. This stabilizing control is suitable for general-purpose inverters that drive various types of motors     

A kinetic study of 3-chlorophenol enhanced hydroxyl radical generation during ozonation

Hydroxyl (OH) radical is proposed as an important factor in the ozonation of water. In the present study, the enhancing effect of 3-chlorophenol on OH radical generation was mathematically evaluated using electron spin resonance (ESR)/spin-trapping technique. OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO–OH. The initial velocity of DMPO–OH generation in ozonated water containing 3-chlorophenol was quantitatively measured using a combined system of ESR spectroscopy with stopped-flow apparatus which was controlled by home-made software. The initial velocity of DMPO–OH generation increased as a function of the concentration of ozone and the more effectively of 3-chlorophenol concentration. The relation among ozone concentration, amount of 3-chlorophenol and the initial velocity (ν₀) of DMPO–OH generation was mathematically analyzed and the following equation was obtained, ν₀ (10⁻⁶M/s)={9.7×[3-chlorophenol (10⁻⁹M)]+0.0005} exp(57×[ozone (10⁻⁹M)]). The equation fitted very well with the experimental results, and the correlation coefficient was larger than 0.99. The equation for the enhancing effect by 3-chlorophenol should provide useful information to optimize the condition in ozone treatment process of water containing phenolic pollutants.     

Dynamic structures of motor proteins myosin and kinesin, and switch protein troponin as detected by SDSL-ESR

We have studied biological nano-machines, motor and switch proteins operating as supramolecular complexes by electron spin resonance (ESR) and found key features of their molecular movements. In all the systems, the specific movements of elements or domains were detected and quite dynamic at nanometer scale. We have observed two broad but distinct orientations, separated by a 25 degrees axial rotation, of a spin label attached specifically to the light chain (LC) domain of myosin motor in the muscle fibers. The distribution became only narrower upon muscle activation. ESR spectrum from the spin label of the neck-linker of dimeric kinesin motor consisted of immobilized and mobilized components and did not exhibit nucleotide-dependent mobility change. The distance between two labels of kinesin dimer was also measured by spin dipole-dipole interaction, showing a broad distribution and a nucleotide-dependent change on the nanometer scale (>1.5 nm). These results suggest that two LC domains of myosin and two neck linkers of kinesin play a similar role for sliding movement using two conformations. The spin label of the skeletal (Tn)-I regulatory domain (TnIreg) showed a large mobility change by Ca2+ ion suggesting a Ca-induced switch movement of TnIreg. Spin dipole-dipole interaction showed that in reconstituted muscle fibers both skeletal and cardiac TnC undergo Ca2+-induced structural change that is thought to be essential for TnIreg movement. We also succeeded in fixing the newly-synthesized bifunctional spin label rigidly on the TnC molecule in solution, indicating that we can determine the precise coordinate of the spin principal axis of troponin on the oriented filament.     

Positologica: A Positron ECT Device with a Continuously Rotating Detector Ring

A rotary positron emission computed tomography device is developed for human brain and animal studies. The device utilizes 64 rectangular BGO detectors arranged at unequal spacing on a circular ring. The detector ring is continuously rotated at a constant speed of 60 rpm or less. This single continuous motion of the ring with the detector array provides excellent sampling characteristics and high detector redundancy. The device has a field of view 24 cm in diameter with a slice thickness adjustable from 1 cm to 2 cm. Measured width of system response to a 2 mm diameter line source is 5.8 mm FWHM at the center and less than 9 mm FWHM within a circle 16 cm in diameter. Measured sensitivity including scattered coincidence events is about 17 kcps/pCi/ml for a 20 cm diameter water phantom and 2 cm thick slice.     

Preparations of Solid Particulates of Amino-Pyrine-Barbital Complex (Pyrabital) wiithout Autoxidation Ey a Spray Drying Technique

Aminopyrine, barbital and colloidal silica dispersed in buffer solutions having pH 5.46 to 8.01 were spray-dried by a centrifugal wheel atomizer at 130 ± 5°C. When the pH of the feeding liquid for spray drying was 5.70 to 7.24, the resultant product was a mixture of amlnopyrine-barbital complex (pyrabital), aminopyrine and the exci-pient. When the pH was lower than 5.84 or higher than 7.84, barbital or sodium barbital coexisted in the above mixture products. Autoxidation of aminopyrine occurred during the spray drying was greatly prevented by introducing chelating agent, e.g. ethylenediaminetetraacetic acid and glycine, or antioxidation agent, e.g. sodium thiosulfate and citric acid in the feeding liquid. It was also found that reducing the pH of the feeding liquid effectively depressed the autoxidation of aminopyrine.     

Two large subunits of the fission yeast RNA polymerase II provide platforms for the assembly of small subunits

BACKGROUND: We analyse whether the tuberculin skin test is a good survival marker in a cohort of pulmonary tuberculosis patients with HIV infection (PTB/HIV). In all, 494 PTB/HIV patients were enrolled in Barcelona (Spain) between January 1992 and December 1994 in the Tuberculosis Program of Barcelona. The main data problem was the large proportion of missing values in the covariates percentage of T CD4+ lymphocytes and the tuberculin test results: only 157 patients (31.8%) had both covariates recorded. METHODS: Patients were dichotomized into two groups according to their level of immunosuppression (< or = 14 and >14% T CD4+ cells). First, we carried out the semiparametric and parametric complete case analysis. After this, we analysed the data assuming a missing at random non-response pattern. We developed a bootstrap approach where missing data in the markers are imputed via a two-way linear model. Using Weibull regression estimation, we used a multiple imputation scheme to estimate the parameters of interest. RESULTS: We found significative differences for the most immunosuppressed group when comparing positive tuberculin patients with those who were tuberculin negative. From a complete case approach and through a multivariate Cox analysis, we obtained a significant relative hazard of 0.3657 (95% CI: 0.13-1.02; P = 0.054). When a Weibull model was fitted, we estimated a constant relative percentile value of pR = 4.1329 (95% CI: 0.97-17.59). From a missing data approach, we obtain a higher constant relative percentile 5.48 (P = 0.079). CONCLUSIONS: The imputation method allows us to assess the protective character of positivity for the tuberculin test for the lowest CD4+ level. These findings strongly suggest the value of the tuberculin skin test as a qualitative measure of the immunological response and its interest for developing countries where specific laboratory tests are not affordable.