We examined the effects of multiple repetitive airway obstruction (RAO) on arterial oxygen saturation (SaO2) and pulmonary and systemic arterial pressure in eight anesthetized spontaneously breathing dogs. SaO2 was monitored at the tongue with a pulse oximeter. RAO created by an electrical valve that was attached to a tracheal cannula was alternated with seven consecutive spontaneous breaths until the nadir SaO2 (nSaO2) became constant or decreased to less than 35%. Tracheal occlusion durations of 15, 30, 45 and 60 s were chosen arbitrarily. In each animal nSaO2 decreased with every trial number in an exponential fashion, and the rate of nSaO2 fall was greater for the longer occlusion duration. In each animal the increases in pulmonary arterial pressure (PAP) and systemic arterial pressure (SAP) were inversely related to the nSaO2 values, and the relationship between nSaO2 and PAP or SAP was identical for all occlusion durations. Moreover, when the animals breathed pure oxygen and SaO2 did not decrease, there were no significant increases in the PAP and SAP at similar levels of pleural pressure (Ppl). In another six dogs, the effects of RAO on PAP and SAP were compared with those of intermittent hypoxic exposure without apnea, which was achieved by the inhalation of hypoxic gas (4 to 6% O2, 5% CO2 in N2) instead of RAO, to examine the effects of interruption of ventilation. The relationships between nSaO2 and both pressures did not differ significantly from those during RAO.(ABSTRACT TRUNCATED AT 250 WORDS)

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A sympathetic neurogram is potentially useful for the development of a real time total artificial heart (TAH) control system. We used sympathetic tone and hemodynamic derivatives to estimate the following cardiac output in acute animal experiments using adult mongrel dogs. Moving averages of the mean left atrial pressure and mean aortic pressure were used as parameters of the preload and afterload, respectively. Renal sympathetic nerve activity (RSNA) was employed as a parameter of sympathetic tone. Equations for the following cardiac output were calculated using multiple linear regression analysis of the time series data. A significant correlation was observed between the estimated and following measured cardiac output. These results suggest the potential usefulness of the sympathetic neurogram for the real time TAH automatic control system.

An account of a simple method of prodvcing short pulses of radiofrequency energy is given, together with notes on its application in the investigation of wireless echoes of short delay. Details of simultaneous visual and photographic methods of delineating such echoes are also described. The discussion of sample records and results serves as a basis for drawing conclusions concerning the relative advantages of the frequency-change and group-retardation methods of investigating the ionized regions of the upper atmosphere.

A new oxidation reaction at ultralow temperature (-30ºC) by bombardment of O 2 neutral beam can be enhanced at the extremely low activation energy, which can efficiently form a thin oxide film of all transition metal, such as platinum and ruthenium. Meanwhile, a novel neutral beam enhanced chemical etching for transition metals and magnetic materials was proposed without chemical and physical damages at ultralow temperature through Metallic Complex Reaction process. Highly anisotropic etching profile without both any sidewall re-deposition and damages on magnetic properties could be achieved just with a pure chemical reaction between ethanol and metallic oxide with low kinetic energy by neutral beam for the first time. This new etching technology has been considered as a breakthrough technology to develop next generation MRAM devices. IntroductionMagnetic random access memory (MRAM), which can offer similar performance to that of DRAM, higher density than SRAM, and faster speed and longer write endurance with nonvolatility than flash memory, might be suitable for replacement of numerous volatile and nonvolatile semiconductor memories that are currently in use. The etching technology of magnetic tunnel junction (MTJ) stack, which is composed of magnetic materials (nickel-iron alloy (NiFe), cobalt-iron alloy (CoFe) etc.) and transition metals (ruthenium (Ru), platinum (Pt), tantalum (Ta) etc.), is the serious problem to limit the miniaturization of MRAM devices. Several methods have been applied as shown in Table I. Halogen-gas-based reactive ion etching (RIE) require a high temperature (>200°C) due to low vapor pressure, which causes thermal damages to magnetic properties, as well as post-corrosion generation. Conversely, the ion milling was limited by the several problems, such as miniaturization, sidewall re-deposition and physical sputtering damages due to the high energy [1][2][3].In this study, to overcome these processing problems, a damage-free and low temperature (-30°C) neutral beam etching technology [4, 5] without any halogen gases has been proposed for etching transition metals and magnetic materials through our newly proposed Metallic Complex Reaction process. Experimental Figure 1 shows a neutral beam enhanced chemical etching apparatus. Oxygen (O 2 ) and/or argon (Ar) gases are introduced into the plasma chamber, which excited by an inductively couples plasma (ICP) source, and then accelerated Ar + or O 2 + pass through the silicon aperture, and Ar, O 2 neutral beams are efficiently formed by maintaining the kinetic energy without any charge built-up. Then, the ethanol (C 2 H 5 OH or EtOH) gas directly injected into the process chamber without any dissociation in plasmas and directly absorbed on the material surface. Finally, the etching of these materials was investigated by combination of surface oxidation and Metallic Complex Reaction due to bombardment of Ar+O 2 neutral beams. Results and discussionsAs Ta was widely used in MRAM as electrode, Ta etching was investigated through Metallic Complex...

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