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The axial distribution of the electron density and temperature in the discharge plasma of a water-vapor Hall thruster is measured by a cylindrical Langmuir probe using a fast-moving system. They are evaluated in two ways; by integrating full trace of the measured electron energy distribution function (EEDF) and by fitting a Maxwellian EEDF to the low-energy part of the measured EEDF. The ion current density for each species produced by electron-impact ionization is estimated using the obtained electron density and temperature. It is revealed that OH + and H + can be contained other than H 2 O + with non-negligible fractions, causing an additional 20%–25% loss of the anode efficiency estimated by the plume diagnostics. It is also suggested that elastic momentum transfer, electronic excitation, and dissociation to the neutral fragments are more dominant processes than ionization, whereas the electron attachment, rotational excitation and vibrational excitation are minor events among the electron-impact reactions. The subsequent ionization processes from the neutral fragments are also expected to play an important role in determining the effective design and operating parameters for further improvement of the mass utilization efficiency. [ABSTRACT FROM AUTHOR]

The electron energy probability function (EEPF) is experimentally identified in a miniature microwave discharge neutralizer over wide operating conditions. A tiny Langmuir probe coupled with the analog differentiation technique offers precise time-averaged EEPFs over about three orders of magnitude, including high-energy, low-density electrons. The non-Maxwellian, concave EEPFs are observed in all experimental conditions. They approach Maxwellian with higher gas pressure, where they deviate from Maxwellian with the absorbed microwave power. Analyzing the measured EEPFs by the generalized EEPF theory, the index that determines the shape of EEPFs (Maxwellian corresponds to 1) is found to be 0.7 ± 0.15. The ionization frequency is estimated using the measured non-Maxwellian EEPFs, and it is found that one would underestimate the ionization frequency with the Maxwellian approximation about up to ∼ 20 %, the value almost negatively correlating with the shape index. These results also suggest that the electron fluid model in microwave discharge neutralizers leads to the overestimation of the electron temperature and the Bohm velocity. [ABSTRACT FROM AUTHOR]

The ability of the mature mammalian nervous system to continually produce neuronal precursors is of considerable importance, as manipulation of this process might one day permit the replacement of cells lost as a result of injury or disease. In mammals, the anterior subventricular zone (SVZa) region is one of the primary sites of adult neurogenesis. Here we show that doublecortin (DCX), a widely used marker for newly generated neurons, when deleted in mice results in a severe morphological defect in the rostral migratory stream and delayed neuronal migration that is independent of direction or responsiveness to Slit chemorepulsion. DCX is required for nuclear translocation and maintenance of bipolar morphology during migration of these cells. Our data identifies a critical function for DCX in the movement of newly generated neurons in the adult brain.

Embedded systems have been applied widely, not only to consumer products and industrial machines, but also to new applications such as ubiquitous or sensor networking. The increasing role of software (SW) in embedded system development has caused a great demand for embedded SW engineers, and university education for embedded SW engineering has become important. The embedded software engineers should learn system architecture design and hardware (HW) technologies as well as SW technologies. However, only a few universities offer education courses for embedded software engineering that include system architecture design and HW technologies. This paper proposes a student experiment method that is designed to nurture embedded SW engineers by teaching these technologies. The proposed method includes an experiment for embedded SW development, an experiment for embedded HW development and a HW/SW co-design experiment, which help students learn system architecture design skills such as system modeling, HW/SW tradeoff design, and SW and HW module design. A model of each experiment was developed and evaluated. (Contains 5 tables and 11 figures.)

An investigation was carried out into the instability of the crystal/melt interface in Si-rich SiGe, and the effects of the Ge concentration and growth velocity on the periodicity of zigzag facets at the interface were determined. It was found that the periodicity at the onset of instability became shorter with the increasing growth velocity and Ge concentration. [ABSTRACT FROM AUTHOR]

The development of integrated coal gasification combined cycle (IGCC) systems ensures higher thermal efficiency and environmentally sound options for supplying future coal utilizing power generation needs. The Japanese government and electric power industries in Japan promoted research and development of an IGCC system using an air-blown entrained-flow coal gasifier. On the other hand, Europe and the United States are now developing the oxygen-blown IGCC demonstration plants. Gasified coal fuel produced in an oxygen-blown entrained-flow coal gasifier, has a calorific value of 8-13 MJ/[m.sup.3] which is only 1/5-1/3 that of natural gas. However, the flame temperature of medium-Btu gasified coal fuel is higher than that of natural gas and so N[O.sub.x] production from nitrogen fixation is expected to increase significantly. In the oxygen-blown IGCC, a surplus nitrogen produced in the air-separation unit (ASU) is premixed with gasified coal fuel (medium-Btu fuel) and injected into the combustor, to reduce thermal-N[O.sub.x] production and to recover the power used for the ASU. In this case, the power to compress nitrogen increases. Low N[O.sub.x] emission technology which is capable of decreasing the power to compress nitrogen is a significant advance in gas turbine development with an oxygen-blown IGCC system. Analyses confirmed that the thermal efficiency of the plant improved by approximately 0.3% (absolute) by means of nitrogen direct injection into the combustor, compared with a case where nitrogen is premixed with gasified coal fuel before injection into the combustor. In this study, based on the fundamental test results using a small diffusion burner and a model combustor, we designed the combustor in which the nitrogen injection nozzles arranged on the burner were combined with the lean combustion technique for low-N[O.sub.x] emission. In this way, we could reduce the high-temperature region, where originated the thermal-N[O.sub.x] production, near the burner positively. And then, a combustor with a swirling nitrogen injection function used for a gas turbine, was designed and constructed, and its performance was evaluated under pressurized conditions of actual operations using a simulated gasified coal fuel. From the combustion test results, the thermal-N[O.sub.x] emission decreased under 11 ppm (corrected at 16% [O.sub.2]), combustion efficiency was higher than 99.9% at any gas turbine load. Moreover, there was different effects of pressure on thermal-N[O.sub.x] emission in medium-Btu fuel fired combustor from the case of a natural gas fired combustor. [DOI: 10.1115/1.1496772]