A New Liquid Level Sensor for Process-Control Applications

Many process-control systems are air-operated. In such an environment, it would be desirable and economical to use pneumatic sensors. Bubble-back pressure sensors perform quite satisfactorily, but in case of viscous inflammable and slurry-like liquids with a tendency to froth, this level sensor is inadequate. The method suggested in this paper utilizes a pneumatic capacitor, one boundary of which is formed by the liquid level, to modulate a fluid amplifier feedback oscillator. The absence of moving parts and economy obtained makes this method attractive for process-control applications. The system has been mathematically modeled and simulated on an IBM 360/44 digital computer. Experimental values compare fairly well with the theoretical results. For the range tested, the sensor is found to have a linear frequency variation with the liquid level Extended running in the laboratory shows that the system is very reliable. This system has been found insensitive to temperature variations of up to 15ðC

A Fluidic Drive System for Intra-Aortic Balloon Heart Assist Device

Intra-aortic balloon pumping is a counter pulsation technique for temporary circulatory assistance in cardiogenic shock and other low cardiac output conditions. Conventional systems use a balloon at the end of a catheter driven by a solenoid valve, controlled by patient's ECG or ventricular pressure signal. This results in time delay introducted by solenoid spool inertia, gas inertia, and hysteresis effects of the solenoid. Fluidics, because of their non-moving part operation and high switching speeds, minimizes the inertial effects while contributing high reliability. This communication describes a fluidic system developed for driving the balloon accepting electric control signals

A Nonmoving-Part Fluidic Display Using Photoelastic Effect

Digital fluidic and pneumatic systems incorporate displays for the presentation of information to the operator. Displays reported so far for such systems use moving pistons, tapes, and other mechanisms leading to lower reliability. This paper describes a nonmoving part fluidic display employing the photoelastic effect. The display is pressure actuated and has a long life. When fabricated from compatible materials, this device can withstand hostile environments like nuclear radiation, vibrations, etc. The display is compact, economical and is virtually maintenance free. The display unit has been tested in the laboratory for reliability and speed of response

Experimental autoimmune encephalomyelitis - achievements and prospective advances

Multiple sclerosis (MS) is an autoimmune disorder of the CNS. Different subtypes of the disease have been noted, and characterized by distinct clinical courses and histopathologic manifestations. The most intensively studied animal model of MS, experimental autoimmune encephalomyelitis (EAE), classically leads to deficits in motor functions, and is mediated by T helper cells. Recently, T(H)17 cells were ascribed an even greater pathogenic impact than T(H)1 cells, but new findings render this view controversial. Although classic EAE has been an invaluable tool, it does not cover the entire pathogenic entity of MS. Especially B-cell contribution and autoantibody-dependence are not mirrored adequately: therefore, new B-cell-dependent models, such as MP4-induced EAE, have been introduced. Furthermore, certain symptoms and the spontaneous onset of MS are not featured in classic EAE. Herein, atypical and spontaneous EAE models can be used for investigation of common symptoms, such as tremor and ataxia, as well as spontaneous disease development. MS displays a marked inter-individual heterogeneity, and no single model will be able to cover all features. Thus, depending on the objective of one's study, the appropriate EAE model has to be carefully chosen. In addition, refined models should be designed to gain a more complete understanding of MS