Estimation Of Volume Changes Research Articles

Model predictions of volume contractions in transition-metal alloys and implications for laves phase formation—II

A simple cellular model estimate of the site volume changes attending alloying of transition metals with each other, and with alkali and alkaline earth metals is made. Application is made to AB 2 (MgCu 2 and MgZn 2) Laves phases as well as the related AB 5 (CaCu 5 and AuBe 5) structures. Size factors and electron factors are considered as measures controlling the occurrence of Laves phases.

Chest wall configurational changes before and during acute obstructive episodes in asthma.

We induced bronchial obstruction in 7 otherwise healthy asthmatic subjects and then measured the degree of airway obstruction and the dimensions of the chest wall including the anteroposterior (AP) diameters of the upper and lower rib cage and the abdomen and the transverse diameter of the lower rib cage. Airway obstruction was accompanied by a pronounced increase in the end-expiratory AP diameter of the upper rib cage in all 7 subjects and of the low lateral rib cage in 3 of the 4 subjects in whom this was measured. Other end-expiratory dimensions showed variable changes. In 6 of 7 subjects, obstruction caused the lower rib cage to become more elliptical in cross section during inspiration; transient inward motion of the lower anterior rib cage during early inspiration was noted. This latter motion coupled with the continuous outward motion of the upper anterior rib cage produced a pronounced rocking motion of the sternum during inspiration. These distortions of the chest cage were maximal when obstruction was most severe and gradually diminished as obstruction resolved. These inspiratory changes in chest cage cross-sectional configuration are similar to those seen in normal subjects who attempt to overcome external resistive loading by the increased use of inspiratory muscles; the end-expiratory configuration in asthma indicates an increase in functional residual capacity, which is actively maintained. Multiple degrees of freedom of motion of the chest cage exist during obstructive episodes. Estimates of volume change from measurements of rib cage cross-sectional area and abdominal diameter should be made with caution.

Usefulness of Doppler echocardiography in cardiac pacing: assessment of mitral regurgitation, peak aortic flow velocity and atrial capture.

Doppler echocardiographic studies were performed in 14 patients with dual chamber pacemakers. Transmitral flow studies (12 patients) revealed absence of mitral regurgitation (MR) or no change in MR severity in 6, new development or increased MR during VVI and/or short or long AV interval lengths compared to more normal AV intervals (150-160 ms) in 5, and appearance of MR when the pacing mode was changed from VVI to DVI with a fixed AV interval of 250 ms in 1 patient. Aortic peak flow velocity measurements (7 patients) showed significant increases in stroke volume (range 9 to 25%, mean 19.5%) in all patients with DVI/VDD pacing compared to VVI pacing (4 patients) or to shortest available AV interval (3 patients). Presence of Doppler left atrial systolic flow correlated with evidence of atrial depolarization in all 7 patients in whom high quality 12-lead surface electrocardiograms were obtained. Our preliminary study demonstrates the value of Doppler echocardiography in the "fine tuning" of cardiac pacemaker parameters by assessment of presence, absence, or change in severity of MR, estimation of relative changes in stroke volume, and determination of atrial capture in different pacing modes and at various AV intervals.

Estimation of volume changes by comparative chemical analyses in heterogeneously deformed rocks (folds with mass transfer)

This paper presents a method for calculating the volume change between the various sectors of the same heterogeneously deformed layer (fold, shear zone) by comparing the chemical composition of deformed sectors with that of a reference sector. The principle consists of considering some minerals as being insoluble (illite, chlorite) and passively concentrated in deformed zones because of the loss of more soluble minerals (quartz, calcite, dolomite) by pressure-solution. Simple observations can be used to test the validity of the assumptions required to calculate volume change (Δ). In the analysis of a slaty matrix around a ptygmatic fold, a map of Δ values is drawn and these Δ values are shown to be compatible with the general strain pattern. For several limb-hinge pairs of straight-limbed folds, the relations between volume change (Δ), elongation parallel to limb layering ( Δl/ l o) and the angle between limb and hinge (α) are determined. The influence of various parameters (such as temperature, pressure, initial composition and structure of the rock) on these relations, is also pointed out.

High-Pressure Melting Curve ofHe4

The melting curve $P(T)$ of $^{4}\mathrm{He}$ has been measured from 220 to 360 K (8 to 16 GPa); it is found to exhibit a well-defined cusp point at 299 K and 11.65 GPa. The cusp, together with estimates of the relative volume change, points to the existence of a triple point and a new high-pressure phase in solid $^{4}\mathrm{He}$. The melting curve below this point is accurately fitted by theory on the basis of a modified Aziz interatomic potential.

A planimetric technique for measuring deformation of the carotid sinus region.

This paper describes a planimetric technique for measuring the volume of the carotid sinus region from still photographs taken during pressure and volume forcings. The method consists of first digitizing the curves defining the boundary of the carotid sinus and then calculating its volume by assuming that the carotid sinus region is made up of a finite number of circular "pancake" slices. Plots of the calculated volume (Vc) vs. applied pressure forcings (P) were compared with plots of injected volume (Vi) vs. recorded pressure to assess the sensitivity of the method used to calculate volume changes from still photographs. The plots of Vc vs. P were remarkably similar to the plots of Vi vs. recorded pressure, and a plot of Vc vs. Vi was linear, suggesting that this method provides a good estimate of volume changes. Application of this method can yield useful data on mechanisms of the baroreceptor process.

Perception of changes in breathing in normal human subjects.

Respiratory sensation was evaluated in normal subjects from their ability to quantitate changes in tidal volume. Subjects attempted to duplicate or double tidal volumes of different sizes while breathing freely or against a resistive or elastic load. When the mechanical conditions during control and test breaths were constant, tidal volume duplication was accomplished with an error of approximately 100 ml, regardless of the control volume. The error in doubling, however, increased progressively with increasing control tidal volume. There was a greater error in both volume duplication and doubling when the mechanical conditions between control and test breaths were changed. When test breaths against a load followed unloaded control breaths, tidal volume failed to double, but intrathoracic pressure changes twice exceeded control values. Conversely, when unloaded test breaths followed loaded control breaths, pressure changes underwent less than a twofold increase while tidal volume more than doubled. The results indicate that tidal volume changes are normally sensed with considerable accuracy and suggest that both tidal volume per se, as well as the forces generated by the respiratory muscles, are used in the estimation of tidal volume changes.

The development of a red-brown earth. III. The segree of weathering and translocation of clay

The degree of weathering of coarse particles throughout the profile of the Urrbrae loam was evaluated by measuring the CaO: ZrO2 and Na2O: ZrO2 ratios in the 5-125 �m fraction. Ratios showed little variation throughout the profile. There was therefore no evidence to suggest that the large amount of clay in the B horizon was due to a greater intensity of weathering of primary minerals in that part of the profile. Thin sections of soil revealed few void argillans and therefore little direct evidence of clay movement. However, the vo-masepic plasmic fabric and thick stress cutans throughout the B horizon were evidence that forces associated with shrinking and swelling may have disrupted any argillans or prevented their formation. High coefficient of linear extensibility values support this argument. Estimation of volume and weight changes accompanying soil formation showed that there had been a 20 % increase in volume of the soil (and a 126% increase in the B2) but only 1.8% increase in weight. The bulk density of the whole profile decreased 15%. Losses and gains of clay, and the elemental oxides of iron, potassium, silicon and magnesium were partitioned between those due to formation of clay and those caused by migration of clay. The majority of changes were ascribed to clay migration. Clay formation by weathering in position cannot account for the strong textural differentiation of the Urrbrae loam (a Rhodoxeralf). Illuviation of fine clay is the most likely mechanism to account for the high content of clay in the B horizon. The relationship between this work, and that of others on the same profile, is discussed.

Impedance cardiography.

ABSTRACTThe purpose of this review was to integrate recent evidence supporting the reliability of thoracic impedance plethysmography as an estimator of cardiodynamic function. Reports regarding the development of the method for NASA, and numerous investigations comparing impedance cardiography to indicator dilution and other methods were discussed. It was concluded that impedance cardiography provides a reliable intra‐subject estimation of relative changes in stroke volume and cardiac output. However, the reliability of the technique was found to depend greatly upon its use within a limited range of applications. Myocardial contractility and cardiopathology were also considered.

Estimation of stroke volume changes by ultrasonic doppler.

The purpose of this study was to conduct a controlled evaluation of the continuous-wave Doppler technique for the estimation of stroke volume changes. Six anesthetized dogs were studied. Aortic blood velocity was recorded from the suprasternal notch by a special continuous-wave Doppler unit. Cardiac output was varied by fluid infusion and exsanguination, and over 300 simultaneous records of aortic blood velocity and thermodilution cardiac output were taken. Average stroke volume and average systolic velocity integral (SVI), the area under the Doppler velocity curve were calculated. The relationship of SVI to stroke volume was evaluated for each animal using linear regression. Average results were: correlation coefficient 0.95 +/- 0.04 SD; y-intercept 0.38 +/- 0.14 cm(SD); standare error of fit 0.29 +/- 0.03 cm (SD). These data show that the systolic integral of aortic blood velocity was essentially directly proportional to stroke volume, even over a six-fold range. Thus, this technique will provide an accurate non-invasive estimate of changes in stroke volume.

An Experimental Method for Studying In Vivo Gallbladder Absorption

A perfusion technique has been developed for the study of net absorption in the gallbaldder of the cat. The lumen of the gallbladder in situ with intact blood vessels and nerves is perfused at a constant rate with bile or a solution of known composition. Differences in volume input and output from the gallbladder are measured with a volume transducer, which in the absence of changes in gallbladder volume reflects net water absorption. By adding polyethylene glycol to the perfusate, net water absorption rate can be calculated from the changes in concentration of this test substance regardless of gallbladder motility. A combined use of these two methods makes possible a concomitant estimation of net water absorption and changes in gallbladder volume. The technique was tested and used for the study of net water absorption from bile, saline and isotonic mannitol solution in the gallbladder lumen.

The thermal transition behavior of polyorganophosphazenes

The thermal transition behavior of poly[bis(trifluoroethoxyphosphazene)] (I) and two samples of poly[bis(p-chlorophenoxyphosphazene)] (II) have been studied as representative alkoxy- and aryloxy-substituted polyorganophosphazenes. Several of the polymers of this class are reported to exhibit two first-order transitions, denoted herein as T (1) for the transition from a crystalline to mesomorphic state and Tm for the true melt. Studies of these two polymers were undertaken to gain a further understanding of this behavior. Optical microscopy on a solution-cast film of I showed that the details of spherulitic morphology persist through T(1) = 90°C and remain undisturbed through the temperature interval up to Tm = 240°C. The study of II by x-ray diffraction reveals that two sharp lines are observed above T(1) = 165°C and that orientation is not randomized upon heating to temperatures as high as 238°C. Considerable improvement in the crystalline diffraction pattern results from the thermal treatment. A detailed examination was also made by differential scanning calorimetry (DSC) of the effects of cycling through T(1), annealing in the temperature interval between T(1) and Tm and for I, the influence of controlled crystallization from the melt. The results indicate that the organization in the mesomorphic state, as influenced by thermal history, has a profound affect on the peak position, area, and sharpness of the endotherm at T(1). For I, the apparent heat of fusion at T(1) is about ten times greater than at Tm, whereas for II, no DSC peak is observed at Tm = 365°C, suggesting that the ratio of the heats of fusion at T(1) and Tm is greater than 50. However, estimated volume changes at the two transitions are nearly equal. These results are compared with those of other polymers which exhibit an intermediate state of order and with molecular liquid crystals.

Haemodynamics and body fluid volumes in response to fluid loading in conscious dogs: non-excretory renal influences.

1. Twelve conscious, chronically instrumented dogs were subjected to rapid loading with sodium chloride solution (150 mmol/1; saline) before and 1 day after bilateral nephrectomy (six dogs) or ureterocaval anastomosis (six dogs). Measurements were performed up to 3 h after the fluid load and included cardiac output with an electromagnetic flowmeter, mean arterial pressure and right atrial pressure with chronically implanted catheters, interstitial fluid pressure with a plastic capsule, heart rate, extracellular fluid volume, erythrocyte volume, plasma volume, plasma protein concentration and other variables. 2. The increase in cardiac output in response to saline load was significantly prolonged in the anephric dogs compared with those with uretero-caval anastomosis; mean arterial pressure, right atrial pressure and heart-rate changes were similar in both groups. 3. Plasma volume appeared to increase more in the anephric dogs than in those with uretero-caval anastomosis during the first hour after the infusion, although conflicting results were obtained with different estimates of plasma volume changes. Interstitial fluid pressure increased significantly less in the anephric dogs in the early stages of the fluid load. 4. Effective vascular compliance (the ratio of the change in blood volume to the change in right atrial pressure) appeared increased in the anephric dogs. On the other hand, the change in cardiac output for a given change in right atrial pressure was found to increase after bilateral nephrectomy. 5. It is suggested that the prolonged increase in cardiac output observed in anephric dogs was not the consequence of preferential plasma volume expansion nor of decreased venous compliance, but may reflect an alteration in the cardiac function curve.

Changes in total plasma content of electrolytes and proteins with maximal exercise.

To determine to what extent the increases in concentration of plasma proteins and electrolytes with short maximal work were a result of hemoconcentration, the changes in plasma volume and total content of the plasma constituents were simultaneously evaluated. The results obtained from six human subjects indicated that in comparison to preexercise values there was a net decrease in total content of plasma protein, sodium, and chloride in the first 2 min of the postexercise period, due primarily to a significant loss (13-15%) of plasma fluid. The total plasma potassium content was increased immediately after exercise but was significantly below the preexercise plasma content after 2 min of recovery.

Blood volume changes in cyanotic congenital heart disease

Simultaneous red cell volume and plasma volume determinations were performed in 20 patients with cyanotic congenital heart disease. Significant hypervolemia was shown to result from an increased red cell volume. Plasma volume may be reduced but usually remains within the normal range. The good correlation between the venous hematocrit and red cell volume per kilogram provides the basis for the estimation of the red cell volume from the venous hematocrit. The common clinical practice of estimating the degree of hypoxemia from the red cell volume (or hematocrit) is at best very gross due to the large variability of the red cell volume at any given level of arterial oxygen saturation in patients with cyanotic heart disease. Red cell volume and plasma volume should be independently and simultaneously measured if accurate estimates of total blood volume changes are desired. Blood volume measurements serve as an index and guide in the medical and surgical treatment of polycythemic cyanotic patients.

Sediment budget along a barrier island chain

The sediment budget for a stretch of coast along a barrier chain is calculated through use of historical records, covering a time span of nearly 100 years, mapped short-term changes, and estimates of volume changes caused by physical processes. For the section studied along the southeastern United States, accretion has exceeded erosion. The sediment deficit requires an input at an average rate of 796,000 m 3 (1,041,000 cubic yards) annually. This deficit is partially filled by longshore drift from adjoining sections and by biogenous contributions. Currents are insufficient to carry material from the mainland across the lagoons. Longshore drift and biogenous source cannot account for approximately 337,000 m 3 (441,000 cubic yards) of sediment annually. It is postulated that this material is being moved in from a reservoir on the continental shelf. This reservoir is either the unconsolidated relict sediments or outcrops of poorly consolidated Tertiary rocks which are only thinly veneered by Holocene sediments.

High Pressure Manganin Gauge with Multiple Integral Calibrants

A high pressure Manganin gauge with multiple integral calibrants has been developed. It allows accurate and continuous pressure measurement in the 100-kbar range at both room and elevated temperatures. The gauge is designed for use in piston-cylinder, multianvil, and other relatively large volume pressure apparatus. One modification of the gauge consists of a Manganin coil wound on a threaded insulating sleeve which encloses a core of primary calibrants. Bismuth, thallium, and barium have been used for calibrants because they provide four widely separated fixed points in the 100-kbar range. The principle of the gauge's operation is based on (a) the nearly linear dependence of the resistance of Manganin on pressure, (b) the volume discontinuities accompanying pressure-induced first-order phase transitions in the calibrants, and (c) the appreciable strength and rigidity at high pressure of commonly used solid pressure-transmitting media. The over-all response of the gauge consists of nearly linear segments of increasing resistance vs pressure between well-established fixed points. The extension of the range of the gauge to higher pressures and its use for semiquantitative estimates of unknown volume changes accompanying polymorphic transitions are described.

Blood, Plasma, and "Drawn Blood" Volumes in the Rat

Summary1. Blood and plasma volumes have been determined in the normal albino rat, and have been found to be approximately related to a power of body weight, the deviation being ascribed to deposition of avascular fat as the rat matures. There appeared to be no significant difference in this regard between the sexes.2. An estimation of blood volume changes may be made from the “drawn blood” volumes.

Dilatometric Ultra-Micro-Estimation of Peptidase Activity

As appears from recent publications of Indian workers (Sreenivasaya and Bhagvat1, compare also Rona and Fischgold2), a considerable volume change is observed in systems in which enzymatic cleavages take place. This volume change may be applied to the estimation of enzyme activity, and the dilatometric methods thus developed possess certain advantages, among which may be mentioned the continuous observation of the undisturbed enzymatic process. While looking around for possible means of refining the histochemical methods previously de-scribed (Linderstrom-Lang and Holter3), I came across the falling drop method for the measurement of specific gravity (Barbour and Hamilton4), a method which recently was re-investigated and improved by Fenger-Eriksen, Krogh and Ussing5. Experience with this method led to the development of a static principle of measurement especially suited for estimation of volume changes in small drops and therefore for micro-estimation of enzyme activity. The following description is concerned only with the application of the method for this latter purpose, but the method may prove useful for the estimation of specific gravity also in other cases.

Effect of respiration on cardiac output: Eyster, J. A. E., and Hicks, Earl V.: Am. J. Physiol. 104: 358, 1933

Simultaneous red cell volume and plasma volume determinations were performed in 20 patients with cyanotic congenital heart disease. Significant hypervolemia was shown to result from an increased red cell volume. Plasma volume may be reduced but usually remains within the normal range. The good correlation between the venous hematocrit and red cell volume per kilogram provides the basis for the estimation of the red cell volume from the venous hematocrit. The common clinical practice of estimating the degree of hypoxemia from the red cell volume (or hematocrit) is at best very gross due to the large variability of the red cell volume at any given level of arterial oxygen saturation in patients with cyanotic heart disease. Red cell volume and plasma volume should be independently and simultaneously measured if accurate estimates of total blood volume changes are desired. Blood volume measurements serve as an index and guide in the medical and surgical treatment of polycythemic cyanotic patients.