Water Cushion Research Articles

Study of cell deformability by a simple method

Cell deformability plays an important role in many immunological processes, such as phagocyte chemotaxis and endocytosis. The most widely used method of assay consists in aspirating cells into glass micropipettes and measuring the length of the protrusion induced by a given pressure, or the minimum pressure required to drive cells into the micropipette. This procedure requires specialized equipment and delicate manipulation. The present report describes a simpler procedure: cells are centrifuged in petri dishes floating on a water cushion, then fixed and coated with 0.8 μm diameter latex beads, which allows rapid and accurate determination of their height. This method is compared with the micropipette technique by studying lymphocyte and macrophage-like cell lines in physiological medium and in the presence of a divalent cation chelator or a microfilament inhibitor. In addition to simplicity, the main advantages of this technique are that (i) many cells may be examined within a reasonable period of time, which allows testing of heterogenous cell populations, and (ii) unexpectedly, centrifugation was quite harmless under our experimental conditions, since it did not impair cell proliferative ability nor phagocytic ability. It is concluded that the method may be used in clinical laboratories to explore phagocyte dysfunctions, as well as in experimental studies.

The water cushion in dermatological diagnostic ultrasound. A new method.

A novel way of using diagnostic ultrasound in the examination of the skin is presented. A water-filled surgeon’s glove acts like a water-cushion, providing more detailed and precise information.

Choosing a Wheelchair Cushion

A preliminary survey of twelve cushions on the standard 8L chair suggests that sheepskin and ministry cushions compare favourably with commercial cushions in respect to pressure and displacement characteristics. Ripple and water cushions were best.

On the water cushion between Sabo main and counter-dam

On the water cushion between Sabo main and counter-dam

The Height of a Deflector at the End of a Basin of Water Cushion Type Torrent Intakes

The Height of a Deflector at the End of a Basin of Water Cushion Type Torrent Intakes

Practical Use of Drill-Stem Tests

Abstract Drill-stem testing has advanced from simple sampling of the formation to complete pressure buildup analysis. This paper reviews the mechanical arrangement of the tool, its running and pressure measurements. Various typical drill-stern test pressure charts are shown as an aid in trouble-shooting. Purpose THE ORIGINAL PURPOSE of drill-stem tests included recovery of a sample of the formation fluids and possibly measurement of the formation pressure. Today, the nature and use of the drill-stem test is more sophisticated and most techniques developed for drawdown and buildup tests have been adapted to the shorter drill-stem test. These might include computation of formation permeability, k, skin, s, flow efficiency or damage ratio, D.R., productivity index, P.I., and radius of investigation, ri. At times, reservoir discontinuities such as faults, small reservoirs, two-layer performance, lenses in the pay and fluid contacts may be recognized. A sample of the formation fluids is usually caught at near formation pressure during the test and brought to the surface without release of pressure. If properly removed and transported, such sample might be analysed in a PVT laboratory. At present, the sample usually is only used to establish fluid-type, gas-oil ratio, viscosity, gravity, etc., as measured in the field. In a drill-stem test the pipe above a shut-off valve is filled with air adjusted by water cushion as the pipe is lowered into the mud-filled well. This valve can be intentionally opened and closed after the pipe has been lowered to the desired depth and packer, set to seal off the mud liquid within the annulus of the well. Thus the well may be produced against a controlled amount of back pressure when the tool is initially opened. Test Procedure-Mechanical Equipment Most drill-stem tests taken today are using equipment and procedures developed by major service companies. Some of the tools involved and typical charts for two such companies are included in this paper as exhibits A and H, respectively, to give the reader an appreciation of complexity. Two or more bottom hole pressure gauges are usually employed. The upper gauge measures the pressure inside the drill pipe or tubing string below the shut-in valve. The lower gauge measures the pressure on the outside of the tool. Both gauges are located near the bottom of the equipment. A section of slotted pipe is used to permit entry of the fluids from the well bore below the set packers into the inside of the string of pipe. To reduce buildup of pressure ahead of the unset packer while it is being lowered into the well, fluids are permitted to flow through these slots and various other mechanisms located below the shut-in tool. Such fluids constantly move from below the unset packer through the pipe to the annulus above the packer while the tools are run into the well. In most cases this technique results in a shorter running time without damage to the tools or plugging of the slots or other restrictions in the flow string below the shut-in tool in the drill pipe.

HYDRAULICS OF WATER CUSHIONS

HYDRAULICS OF WATER CUSHIONS

LUMBAR PUNCTURE AND THE PREVENTION OF POSTPUNCTURE HEADACHE

As the result of experiments made during 1923 and my experience since that time with the use of a small needle 1 having a round, sharp, tapering point, I am convinced that postpuncture headache is caused by trauma to the spinal dura sufficient to result in excessive leakage of cerebrospinal fluid to the point at which the brain is left without a water cushion. These experiments demonstrated that a greater trauma was produced by the use of a needle with a blunt cutting point than by a needle of the same caliber with a point rounded, tapering and sharp. It was also shown that leakage followed puncture of the spinal dura in every instance in which the membrane was suspended and filled with water, and that the amount of leakage was in direct relation to the size of the needle used (Fig. 1). The problem is, then, to do the

HOT WATER CUSHIONS IN CHOLERA

HOT WATER CUSHIONS IN CHOLERA

On a water cushion for electrical machines

On a water cushion for electrical machines