Displacement Volume Research Articles

Effects of high-frequency oscillatory ventilation on vagal and phrenic nerve activities.

This study was undertaken to define the mechanism for the respiratory inhibition observed during high-frequency oscillatory ventilation (HFOV). The effects of HFOV on the activities of single units in the vagus (Vna) and phrenic nerves (Pna) were examined in pentobarbital-anesthetized dogs. The animals were either ventilated by intermittent positive-pressure ventilation (IPPV) with and without positive end-expiratory pressure (PEEP), or by HFOV at a frequency of 25 Hz and pump displacement volume of 3 ml/kg. In 13 vagal units the Vna was much higher during HFOV than during IPPV or airway occlusion at a matched airway pressure. Ten units in the phrenic nerves were examined, and Pna (expressed as bursts/min) was attenuated by HFOV in all of them. In four of them, the effect of cooling the vagi to 8-10 degrees C on Pna was examined, and it was found that HFOV failed to alter the Pna. We conclude that 1) HFOV stimulates the pulmonary vagal afferent fibers continuously and to a degree greater than that due to static lung inflation and increased airway pressure and 2) the increased vagal activity during HFOV probably causes phrenic nerve activity inhibition.

Male–female differences in predicting displaced volume: Strategy usage, aptitude relationships, and experience influences.

Male–female differences in predicting displaced volume: Strategy usage, aptitude relationships, and experience influences.

Male-female differences in predicting displaced volume: Strategy usage, aptitude relationships, and experience influences.

Male-female differences in predicting displaced volume: Strategy usage, aptitude relationships, and experience influences.

The Annual Cycle of Zooplankton in a Long Island Estuary

Zooplankton and chlorophyll-a samples and associated hydrographic data were collected at approximately weekly intervals in the Peconic Bay estuary for most of the period between May 1978 and June 1979. Surface zooplankton samples were obtained by simultaneously-towed 73 μm- and 202 μm-mesh nets, and subsurface samples were collected with 505 μm-mesh nets. Zooplankton numbers and displacement volumes fluctuated widely throughout the year, with highest values in early spring and summer. Juvenile or adult copepods accounted for means of 90.0% and 85.0% of the animals recorded for the 202 μm- and 73 μm-net samples, respectively. The combination of Acartia tonsa and A. hudsonica adults+copepodids accounted for a mean of 81.4% of the zooplankton recorded for the 202 μm-net samples, and the combination of copepod nauplii, Acartia spp. adults+copepodids, Oithona colcarva and Parvocalanus crassirostris accounted for a mean of 82.7% of the animals recorded for the 73 μm-net samples. Copepod nauplii were the most abundant zooplankters collected in the 73 μm-net samples, and they were generally collected in higher numbers than the total number of animals in the 202 μm-net samples. During the colder months, late copepodids and adults of larger copepod species comprised greater proportions of the total zooplankton than during the warmer months when nauplii and copepodids of smaller copepod species were predominant. The ctenophore Mnemiopsis leidyi and the medusa Cyanea capillata also had periods of abundance during warmer months. Differences between numbers of larger zooplankters collected over different depth intervals or in successive replicate tows over the same depth intervals, reveal the likely effects of both vertical and horizontal patchiness. Comparisons of zooplankton numbers from the present investigation, which were obtained with relatively fine-mesh nets, with values from previous studies in adjacent waters which used coarser-mesh nets, suggest that many previous investigations have seriously underestimated the numbers of smaller zooplankters, particularly copepod nauplii.

Simulation of Miscible Displacement in Full-Diameter Carbonate Cores

Abstract Miscible gas displacement data obtained from full-diameter carbonate reservoir cores have been fitted to a modified miscible flow dispersion-capacitance model. Starting with earlier approaches, we have synthesized an algorithm that provides rapid and accurate determination of the three parameters included in the model: the dispersion coefficient, the flowing fraction of displaceable volume, and the rate constant for mass transfer between flowing and stagnant volumes. Quality of fit is verified with a finite-difference simulation. The dependencies of the three parameters have been evaluated as functions of the displacement velocity and of the water saturation within four carbonate cores composed of various amounts of matrix, vug, and fracture porosity. Numerical simulation of a composite core made by stacking three of the individual cores has been compared with the experimental data. For comparison, an analysis of Berea sandstone gas displacement also has been provided. Although the sandstone displays a minor dependence of gas recovery on water saturation, we found that the carbonate cores are strongly affected by water content. Such behavior would not be measurable if small carbonate samples that can reflect only matrix properties were used. This study therefore represents a significant assessment of the dispersion-capacitance model for carbonate cores and its ability to reflect changes in pore interconnectivity that accompany water saturation alteration.

Canine left ventricular volume and mass during thoracotomy by two-dimensional echocardiography: Increased ventricular mass after ischemia and reperfusion

Left ventricular end-diastolic volume ( V c) and mass ( M c) were studied in 10 dogs by two-dimensional echocardiography after thoracotomy and construction of a pericardial well filled with sound-conducting gel. Five selected LV sections were obtained in vivo by two-dimensional ultrasound. After X-ray angiography and thermal dilution cardiac outputs, 9 of the 10 hearts were fixed by glutaraldehyde coronary perfusion while filling pressures were maintained equal to LVEDP and RVEDP in vivo. Silastic casts of the left ventricle were used to measure cavity volume ( V c) by displacement, and LV mass was determined by weighing ( V pm). Study of postmortem casts with a Simpson's rule algorithm revealed that volume calculations with two of six possible pairs of orthogonal sections were congruent with the line of identity vs cast displacement volume. Optimum results in vivo were obtained from averaged data based on these section pairs (from three echo sections) as V c = 0.94 V c + 0.2 ( r = 0.88). LV mass was given by M c = 0.95 M pm + 6.6 ( r = 0.90). Systolic volume, stroke volume, and ejection fraction were less satisfactory, reflecting difficulties with long axis sections during systole in the open chest. To examine the suitability of these methods for physiologic studies, LV mass was measured before and after 30 min of normothermic ischemic arrest and reperfusion in six dogs. LV mass increased from 109 ± 7 (SE) g before ischemia to 153 ± 13 g after ischemia ( P < 0.01). Two-dimensional echocardiography thus demonstrates unique potential for experimental cardiovascular physiology.

Lung tissue volume estimated by simultaneous radiographic and helium dilution methods.

The pulmonary total tissue volume (blood, extravascular water, and dry tissue volume) was measured by finding the difference between the radiographic displacement volume of the thorax (RDVT) and the lung gas volume. Simultaneous determinations of RDVT and gas volume were made in 10 healthy subjects sitting upright. RDVT was determined from posteroanterior and lateral chest radiographs, a computerised modification of the Barnhard method being used; and gas volume was measured by helium dilution with each radiographic exposure. At functional residual capacity pulmonary total tissue volume was 843 +/- 110 ml (1 SD). The density of the lung (ml tissue per ml tissue and gas) was 0.19 +/- 0.03 (1 SD). This method, different in principle from indicator-dilution and acetylene rebreathing studies, provides measurements of total tissue volume.

Morphological Grading of White Pine Nursery Stock

In the spring of 1975 regular white pine (Pinus strobus L.) stock, 3 + 0 and 2 + 2, were measured for top length, root length, stem diameter, and top-root ratio by volume of water displacement and then planted at the Midhurst Research Unit. Survival and growth was measured for 5 years.The 2 + 2 stock was superior in survival, growth and cost for a specified stand (aggregate height per unit area at 5 years). Top length, stem diameter and root volume were found to be highly significant predictors of subsequent performance. Tentative recommendations are given for 2 + 2 white pine stock specifications as minimums of: 20 cm for top length, 0.40 cm for stem diameter, 12 ml for root volume, and a top-root ratio less than 3.5:1.

A developmental analysis of certain Piagetian concepts among some Nigerian children

AbstractThe concepts of distance, area, and the coordinate reference systems were investigated in relation to the displacement volume task among 300 randomly selected primary and high school children in Nigeria. Piaget and Inhelder (1971) theorized a developmental progression in the acquisition of these concepts among Genevan children, and a number of studies have confirmed pancultural stability in the acquisition of these concepts. Four tasks were used to investigate the acquistion of these concepts developmentally, and the data obtained were analyzed by the chi‐square, Pearson correlation coefficient and the 50% success criterion suggested by Laurendea and Pinard (1962, 1970). The data confirmed Piaget's theorizing but when compared with similar studies in Europe and America (Lovell (1971), Dasen (1972), &amp; Karplus et al. (1977), a “developmental lag” of about two years was observed among the Nigerian Ss. The concept of horizontal decalages was discussed in relation to the data including some implications for science teaching particularly in developing countries.

2, How big are the lungs?

The lungs are much the same size as a large old-fashioned kettle. Like the lungs, the ‘empty’ kettle is an irregular air-filled vessel with a complex curved surface and a single long tube linking the air outside to that within. Its volume can be measured in many ways. We could seal the spout, sink the kettle in a bath and note the volume of water dislodged. In effect, we would be using strings of water molecules to measure an almost infinite number of dimensions across the kettle, and then be packing all the strings together, or at least another supposedly equal number of them in the dislodged fluid, to determine the volume displaced by the external surface of the vessel. Although it would be laborious, we could take a pair of calipers and calculate that volume in a nearly identical manner, directly or from the size of its shadows. However, the fewer the dimensions we took, the more vulnerable the estimate would be to assumptions about the types of curves linking one point on the surface to another. In much the same way, we could weigh the kettle before and after filling it with water or helium, taking care to dislodge all the air trapped within. We would need to devise some test to prove that all the air had gone. The weighings would give us the displacement volume of the internal surface of the kettle and that would differ from the external measurement by the volume of material of which the vessel was made. We could approach the problem differently, inject a known amount of air through the sealed spout, note the pressure rise it caused and, using Boyle’s law, calculate the volume of compressible gas within. Or, we could inject a known amount of an alien gas, ensure that it was thoroughly mixed (which is not easy in rigid vessels) and determine the volume of gas that was accessible within. Volume is an odd and complex attribute: a sphere and some regular polyhedra such as a cube are the only solids whose volumes can be determined from a single dimension, and even then a test of sphericity or its equivalent is required if we are to calculate the volume of such a shape with confidence. Similarly, a cone and a cylinder are perhaps the only common objects whose volumes can be calculated from two dimensions, but tests of circularity of cross-section, and of straightness of ends and sides, will be required before these can be relied on. Normally, to measure the volume of a rigid object, we have to use some ‘digital’ counters such as water or helium molecules (or ping-pong balls in cars), much smaller than the volume to be determined, and depend on them distributing themselves in an orderly way within or around its volume. If we tried to measure the volume of a floppy half-filled balloon, instead of a kettle, we would run into quite different problems. Any attempt to submerge the balloon would

LUNG TISSUE VOLUME ESTIMATE BY SIMULTANEOUS RADIOGRAPHIC AND HELIUM DILUTION METHODS

Lung tissue volume measurement adds quantitative information to the diagnosis and assessment of the response to therapy in patients with increased extravascular lung water. Indicator-dilution and acetylene rebreathing measurements are difficult and limited to research investigations. We reasoned that total lung tissue (lung tissue, blood and extravascular water) volume (VTT) could be estimated using the difference between radiographic displacement volume of the thorax (RDVT and alveolar gas volume (VA) by helium rebreathing. Ten healthy subjects underwent simultaneous RDVT and VA determinations using upright posteroanterior (PA) and lateral (LAT) chest radiographs and helium rebreathing. RDVT was measured from radiographs using a computerized modification of the Barnhard method (Barrett WA et al: 1976 AARD 113: 239–244). VA was obtained simultaneously following the PA and LAT radiographic exposures. The average VTT at functional residual capacity (FRC) was 730 + 75 ml which includes capillary blood, most of the major arterial and venous blood in the pulmonary circulation, extra-vascular water and lung tissue (dry weight). This estimate is greater than those measured with acetylene (approximately 630 ml) (Farney FJ, Morris AH, Gardner RM, Armstrong JD, J Appl Physiol 1977 43: 246–253) but falls below the expected by 135 ml (lung dry weight 160 ml, lung blood volume 320 ml and extravascular water 385 ml). The agreement of radiographic estimates of total tissue volume with data obtained by other methods is promising and may provide accurate measurements of VTT in selected patients with uncomplicated heart failure or diffuse interstitial processes.

Morphological Grading of White Spruce Nursery Stock

An experiment was begun in 1974 to examine morphological criteria of 3 + 0 and 2 + 2 white spruce planting stock in relation to subsequent performance. Trees (250) of each age-class were obtained from Midhurst Nursery and measured (top length, stem diameter and top-root ratio by volume of water displacement) and then planted on a cultivated site at Midhurst Research Unit. Survival and growth was measured for 6 years after planting.The 3 + 0 seedling stock was found to be inferior in survival, growth and cost for a stated objective aggregate height of stand. Top length, stem diameter and root volume were all good indicators of subsequent height growth. Tentative recommendations for 2 + 2 white spruce are: a minimum 22 cm top length, minimum 4 mm stem diameter, minimum 5 ml root volume, and top-root ratio range of 1.0 to 3.5:1.

Bongo Net Retention Rates as Effected by Towing Speed and Mesh Size

A comparison of 0.253- and 0.333-mm mesh bongo net retention rates at towing speeds of 1.5 and 3.5 knots showed no significant mesh size related variation in filtration efficiency or in abundance of larval herring at either towing speed. For 1.5-knot tows there was no significant mesh size difference in larval herring length frequency distribution. For 3.5-knot tows, the distributions of lengths were significantly different for the two mesh sizes. The condition of herring larvae was noticeably better in the 1.5-knot tow samples (3%, of yolk-sac larvae caught in 3.5-knot tows had their yolk sac intact compared to 50% from 1.5-knot tows). Feeding incidence was higher for larvae caught in 1.5-knot tows (71%) than for larvae caught in 3.5-knot tows (50%).At a towing speed of 3.5 knots the 0.253-mm mesh zooplankton displacement volumes were significantly greater than the 0.333-mm mesh displacement volumes. At a towing speed of 1.5 knots the difference in displacement volumes was not significant. Adult Oithona spp. and Pseudo-Paracalanus spp., unidentified copepodites, and adult and juvenile Hyperia spp. were caught in significantly greater numbers by the 0.253-mm mesh net at both towing speeds. The 0.253-mm/0.333-mm abundance ratios were greatest for the smaller and more abundant invertebrate taxa. The variation in zooplankton retention rates resulted in large part from differences in mesh size, although catching efficiency was also influenced by tow speed. A substantial proportion of the food items in the guts of all size groups of larval herring consisted of taxa which were not retained by either mesh net (invertebrate eggs, copepod nauplii, Oithona spp., and Pseudo-Paracalanrrs spp. copepodites). Size was the most important factor in prey selection and the average size of food items increased with increased length of herring larvae. On the basis of this analysis, sampling strategies are suggested for future surveys. Key words: bongo nets, retention rates, ichthyoplankton, larval herring, zooplankton, feeding incidence

Factors determining degree of inflation in intratracheally fixed rat lungs.

The total lung capacity (TLC) of rats was measured in vivo and was compared to the displacement volume of the lungs following intratracheal fixation with glutaraldehyde or formaldehyde solution. When glutaraldehyde was used the speed of infusion of the fixative was an important factor in the final degree of lung inflation achieved. With a low rate of fixative infusion and a final pressure of 20 cm of fixative the glutaraldehyde-fixed lungs inflated to 55% TLC. With a high initial flow of glutaraldehyde and a final pressure of 20 cm of fixative the lungs inflated to 84% TLC. Fixation of lungs inside the intact chest wall was found to result in a higher degree of inflation. With a reservoir height of 20 cm and a low rate of fixative infusion lungs fixed in situ reached 74% TLC, whereas lungs fixed in situ, but from animals that have been exsanguinated prior to fixation, inflated to only 58% TLC. This suggests that the volume of the blood in the lungs prior to infusion of glutaraldehyde influences the degree of inflation achieved. Formaldehyde-fixed lungs required 72 h to be completely fixed and they were inflated to 90% TLC when a reservoir height of 20 cm was used. Because of the slow rate of fixation using with formaldehyde solution the rate of infusion was found not to limit the degree of inflation that could be achieved.

Estimation of lung volumes from chest radiographs using shape information.

The cross-sectional shapes of the chest and its contained structures have been assessed in post-mortem anatomical sections and from computerised tomographic scans in living subjects. These shapes are described by simple equations that can be used to increase the accuracy of measuring lung volumes from chest radiographs. Radiographic estimates of total lung capacity, using the equations, were compared with plethysmographic and single-breath helium dilution measurements in 35 normal subjects. The postures commonly used for taking chest radiographs were found, on average, to decrease total lung capacity (TLC) and to increase residual volume by about 200 ml when compared with the sitting positions used for the other two measurements (studies made in 18 of the subjects). After correction for this effect, the radiographic estimates of TLC, which measure the displacement volume of the lung, exceeded the plethysmographic estimates of contained gas volume by a mean of 720 ml, which was taken as the volume of tissue, blood, and water in the lungs. The single-breath dilution estimates of TLC fell short of the plethysmographic values by a mean of 480 ml, taken as the volume of contained gas that was inaccessible to helium in 10 seconds. The tomographic studies suggested that the radiographic technique of measuring lung displacement volumes has an accuracy of +/- 210 ml. The method is rapid and simple to use and has intra- and inter-observer variabilities of less than 1% and less than 5% respectively.

Silhouette photography of oceanic zooplankton

No adequate method has been available to characterise a sample of Zooplankton quickly and accurately. As Mullen noted1, although relatively rapid, measures of standing crop such as displacement volume, dry weight, carbon content and electronic size spectra do not distinguish clearly between animals and plant or detrital material, much less between herbivores and carnivores. Direct microscopic enumeration has remained the only approach giving information detailed enough for many ecological studies. Unfortunately, this method is time-consuming, it cannot be undertaken routinely at sea, and it is feasible only after chemical agents have been added to ‘fix’ and then ‘preserve’ the sample. With time, plankton samples always deteriorate in preservatives, although the degree of this effect varies with species. We report here that a little-known photographic technique—high-speed silhouette photography2,3—can be used to analyse live Zooplankton samples at sea.

Studies on Characters of Various Impression Materials by means of Holography

The present study is desined to Silicone Rubber Impression materials on manipulated condition, that is impression thickness, making and remove of impression its time elapse of mixing, have influence on occulusal surface and axial surface used with Holography.As the results of these effort, the following conclusions were obtained.1. This study is good method used with the Holography. This method can measured deformation and infinitesimal displacement of dental materials, don't touch the object and that can observe with the bodily eye.2. Silicone Rubber Impression materials showed various displacement volume severally on manipulated conditions.3. Impression surface of axial surface condition that impression thickness 1, 0mm, making of impression after 75 seconds, removed after 5 minutes its time elapse of mixing showed minimum. And the state added between occulusal surface and axial surface, that condition showed minimum displacement volume too.4. Silicone Rubber Impression materials surface keep on after 60 minutes displacement all condition that this study established.

The deep chlorophyll maximum and mesoscale environmental heterogeneity in the western half of the North Pacific central gyre

Abstract A traverse of the western half of the North Pacific central gyre along 28°N from 162°30′W to 146°15′E provided sections of temperature, salinity, chlorophyll-a, PO4, NO2, NO3, O2, sigma-t, and zooplankton displacement volume. The deep chlorophyll maximum known to occur in the eastern half of the gyre extends completely across the Pacific. The section crossed at least two hydrographic features that can be interpreted as rings or eddies. The physical environment in the upper 300 m appears to be heterogenous on a horzontal scale of hundreds of kilometers. Nutrient and chlorophyll distributions parallel the hydrographic features and are equally heterogenous. Large differences exist in species assemblages between a site in the eastern half and one in the western half of the gyre. These differences are consistent with either a two-gyre system of surface circulation or with samples taken at the ends of a cline. Hydrographic data are more supportative of the two-gyre hypothesis.

Method for Accurately Measuring Produced Oil Volumes During Laboratory Waterflood Tests at Reservoir Conditions

Introduction Much usable information can be obtained from laboratory waterflood tests conducted at reservoir temperatures and pressures using reservoir fluids. Consequently, reservoir-conditions waterflood tests have been conducted by several laboratories even though such tests are much more difficult and expensive than routine waterflood tests. One of the most difficult problems with these reservoir-conditions tests is measuring incremental and total displaced oil volumes accurately. This study describes a method that produces a continuous record of oil production during a high-pressure, high-temperature waterflood test. With this method, oil is accumulated in a high-pressure separator, where its volume is monitored with a very sensitive differential pressure transducer. If the dimensions of the separator are selected properly, very small volumes (less than 1% of the pore volumes of typical test cores) can be measured reliably using commercially available pressure transducers. The basic method also can be used for tests involving gas displacing oil or water and water displacing gas. With minor modifications of equipment and operating procedures, produced volumes of gas, oil, and water can be measured during three-phase flow tests. The waterflood technique discussed here now is being used routinely and has proved satisfactory for the past 15 years. Using this method experienced operators easily can record the production history from several core floods running concurrently. EXPERIMENTAL METHOD Fig. 1 schematically shows the main items of required equipment. All components are off-the-shelf items except the core holder and high pressure separator, which must be shop built. During a waterflood test, fluid leaving the core enters a high-pressure separator, where produced oil accumulates in a collecting tube. Both the core and separator are in a constant temperature oven. The separator is a blind cell, thus the inconvenience and hazards associated with viewing windows are avoided. The system is designed so only one phase (gas or water is displaced through a backpressure regulator. This design has two advantages over methods that require all production to flow through a regulator:conventional commercial backpressure regulators can be used without modification to reduce holdup volumes andpressure fluctuations at the upstream side of the regulator are reduced significantly so the pressures in the separator and at the outlet end of the core are kept much more uniform. The difference between pressures at the top of the collecting cube and the top of the annulus is measured with a sensitive differential pressure transducer. The portion of the annulus containing oil and the lines from the separator to the transducer normally are filled with live crude oil. At the start of the test water in the separator should have the same density as the flood water and water initially in the core. SPEJ P. 239

Displacement Volume, An Indicator of Early Formal Thought; Developing a Paper‐and‐Pencil Test

Displacement Volume, An Indicator of Early Formal Thought; Developing a Paper‐and‐Pencil Test