Water-filled Container Research Articles

The origin of the tubular jet

A vertical cylindrical tube is partially immersed in a water-filled container and pressurized to lower the fluid level inside the tube. A sudden release of the pressure in the tube creates a singularity on top of the rising free surface. At the very beginning of the process a jet emerges at the centre of the surface, the strength of which strongly depends on the initial shape of the meniscus. Here, the time-evolution of the complex shape of the free surface and the flow around the cylindrical tube are analysed using high-speed imaging, particle image velocimetry, and numerical simulations. The tubular jet is found to be created by the following series of events, which eventually lead to the flow focusing at the tube's centre. A circular surface wave, produced by the funnelling of flow into the tube, is pushed inwards by the radial flow directly underneath the surface. As the wave moves inward and eventually collapses at the centre of the tube, a bump of fluid grows in the centre due to the converging flow in the bulk. This converging flow continues to feed the jet after the circular wave has collapsed. The singularity of the wave collapse is manifested in the initial sharp tip of the jet. All of the above events are traced back to a single origin: the convergence of the flow as it enters the tube. Movies are available with the online version of the paper.

Archimedes revisited: a faster, better, cheaper method of accurately measuring the volume of small objects

A little-known method of measuring the volume of small objects based on Archimedes' principle is described, which involves suspending an object in a water-filled container placed on electronic scales. The suspension technique is a variation on the hydrostatic weighing technique used for measuring volume. The suspension method was compared with two other traditional water displacement methods of measuring volume, i.e. placing an object in a measuring cylinder and recording the rise in the water level and immersing the object in a water-filled container with an overflow spout to record the volume of overflow. The accuracy and precision of the three methods was compared using ten accurately machined PVC cylinders ranging in volume from 1.5 to 15.7 ml. The mean difference between the actual and measured volumes was 3.3 ± 7.3%, -1.6 ± 7.2% and 0.03 ± 0.45%, for the level, overflow and suspension methods respectively. Each measurement was repeated twice to obtain the reproducibility of the three displacement techniques. The reproducibility was -1.7 ± 8.5%, 0.09 ± 3% and -0.04 ± 0.43% for the level, overflow and suspension techniques respectively. The results show that the suspension technique is more accurate and precise than the traditional water displacement methods and is more accurate than measuring volume using Vernier calliper measurements.

Artifacts of Vena Cava Filters ex vivo on MR Angiography

We evaluated magnetic susceptibility artifacts of nine types of vena cava filters in MR angiography (MRA) at 1.0T ex vivo in order to assess the filters' compatibility with MRA. Each filter (tulip filter, tulip MReye filter, stainless Greenfield filter, titanium Greenfield filter, TrapEase filter, Simon filter, LGM Vena-Tech filter, Antheor temporary filter, and Bird's nest filter) was inserted into an acrylic tube (20 or 25 mm in diameter, 15 or 30 cm in length). Gd-DTPA was poured into each tube at a concentration of 1/500 and each was placed in a water-filled container for imaging. We evaluated artifacts of the filters according to the following criteria: signal void beyond the tube, 3+; signal void within the tube but at more than one-half the diameter of the tube, 2+; and signal void within the tube but at less than one-half the diameter of the tube, 1+. We evaluated artifacts originating at the tip, intermediate portion, and distal end of the filters. We judged the artifacts as follows: tulip (3+, 3+, 3+); tulip MReye (2+, 1+, 1+); stainless Greenfield (2+, 1+, 2+); titanium Greenfield (1+, 1+, 1+); TrapEase (1+, 2+, 1+); Simon (2+, 2+, 1+); LGM (2+, 2+, 1+); Antheor (2+, 2+, 2+); and Bird's nest (3+, 3+, 3+). The numbers in parentheses refer to the degree of signal void at the tip, intermediate portion, and distal end of the filter, respectively. The tulip filter and Bird's nest filter made of 304 stainless steel caused extensive signal voids beyond the areas defined by the filters. The signal voids in the remaining seven filters were limited to within the tube. We concluded that seven of the nine filters were compatible with MRA ex vivo.

Ultrasonography in amphibians

Special anatomic structures of the amphibians ease the ultrasonographic examination (ie, skin, uncompartmented pleuro-peritoneal cavity, fluid within the celom). Heart, liver, gallbladder, fat bodies, stomach, intestines, gonads, kidneys, and bladder are displayable. Main differences to reptile sonography are the hyperechoic liver with only few large vessels, the large sinus venosus, the amount of follicles and ova within the ovaries, and therefore the problems in differentiation between ovary, liver, and fat bodies. The fat bodies of anura are finger-like projections in the celom. The bladder is always visible. Preferred technique involves applying the scanner with the patient in a water-filled plastic container.

The theoretical and experimental evaluation of the heat balance in perfused tissue

Accurate treatment planning is necessary for the successful application of hyperthermia in the clinic. The validity of four different bioheat models or combinations of models is evaluated: the conventional bioheat transfer equation, the limited effective conductivity model, a mixed heat sink-effective conductivity model and a discrete vessel model. The heat balance for the heated volume, and especially the ratio between conductive heat removal and heat escape through the veins, is different for each of these models. Model predictions were compared with results from experiments on isolated perfused bovine tongues. Tongues were suspended in a water-filled container and heated by conduction. The steady state temperature distribution and heat balance were determined at various blood flow rates. Increased blood flow was found to lower the mean tissue temperature and to enhance both conductive and venous heat removal. This result agrees only with the mixed heat sink-effective conductivity and the discrete vessel model predictions. At low flow rates a modified heat sink term should be used because the venous efflux temperature was significantly lower than the mean tissue temperature.

Productivity, Disturbance and Food Web Structure at a Local Spatial Scale in Experimental Container Habitats

We report the results of an experiment using water-filled container analogues of natural treeholes placed in a subtropical rainforest. The source of energy in both experimental and natural systems is detrital leaves. This feature allows the productivity of the systems to be controlled and the effects on various aspects of food web structure to be measured. Ten-fold and hundred-fold reductions in energy input reduced food chain lengths by an extra link. The principal predator was less prevalent in less productive habitat units. Food webs with fewer trophic links and fewer species were found in habitat units that were less productive

Cross-borehole compressional wave imaging of unconsolidated sediments

Cross-borehole elastic wave tomography offers great potential for nondestructive imaging of near-surface sediments, fluids, and soils. This method was used to create a high-resolution tomographic image of velocity structure from simulated sedimentary layers obtained using compressional wave travel times. The image shows three distinct layers and a water-filled container located in the center of the middle layer. An image obtained from computer-simulated travel times shows good agreement with the image from laboratory data. The high-quality data and the resulting image were due in part to a novel transmitter and receiver design. These were composed of cylindrical piezoelectric transducers individually sealed in oil-filled Teflon containers and stacked to form stringers. The transmitters were extremely efficient at coupling energy into the medium. The transmitter frequency was 135 kHz, velocities ranged from 1.4 to 1.8 km/s, and thus wavelengths were 1.0-1.4 cm. The distance between boreholes was 30 cm, with about 60 cm of vertical coverage. >

AN EASILY MADE APPARATUS FOR USE IN "CLOSED SYSTEM" PNEUMOENCEPHALOGRAPHY

The increasing use of pneumoencephalography has led to a search for the safest method which will give the most uniformly satisfactory roentgenograms and the least distress to the patient. Liberson1was the first to advocate the steady withdrawal of cerebrospinal fluid and its simultaneous replacement with gas. He used a double-chambered needle connected with a gas-filled stoppered bottle by two pieces of rubber tubing. He called attention to the rapid fluctuations in intracranial pressure produced by the method introduced by Dandy, employing a single needle and syringe, with alternate withdrawal of fluid and injection of air, and claimed that both greater safety and less discomfort resulted from the use of the simultaneous replacement method. A manometer and syringe were attached to the rubber tubing in Liberson's apparatus. Many modifications have since been described, the addition of a water-filled container through which the injected gas must bubble being the only