Journal articles: 'Pressures'

1

Kindgen-Milles, D., A. Gabriel, R. Buhl, H. Böhner, and E. Müller. "Nasal continuous positive airway pressure: do mask pressures reliably reflect intratracheal pressures?" Critical Care 3, Suppl 1 (1999): P021. http://dx.doi.org/10.1186/cc396.

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Zhou, Yang, Shuanghui Hao, and Minghui Hao. "A two-dimensional numerical analysis of a circular-arc gear pump operating at high pressures and high speeds." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 231, no. 3 (August 27, 2015): 432–43. http://dx.doi.org/10.1177/0954408915602625.

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This paper examines the flow field of a circular-arc gear pump operating at high pressures and high speeds by the commercial finite-volume-based code Fluent. The performance of circular-arc gear pump operating at high pressures and high speeds have been discussed. The mathematical model of the tooth profile is established. The pressures including gears mesh, outlet pressures, and outlet flow rate are studied under different rated outlet pressures and rotational speeds. There are dynamic pressures at clearance between chamber and tip circle of gear. Moreover, parts of radial leakages are prevented by dynamic pressures. The outlet pressures almost remain constant. However, there are strong pressure fluctuations in gears mesh under the high pressures and high speeds. The pressures are several times higher than the rated outlet pressure when the circular-arc gear pump operates at 10,000 r/min and 12,000 r/min. Gear meshing pressure fluctuations increase with the increase in rotational speeds. However, gear meshing pressure fluctuations decrease with the increase of outlet rate pressures. There are rotational speeds and outlet rate pressure critical points for gear meshing pressures, and the variation tendency of gear meshing pressures changes dramatically when it exceeds the critical points. Hence, the research results provide base model for circular-arc gear pump operating at high pressures and high speeds.

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Glucksberg, M. R., and J. Bhattacharya. "Effect of alveolar and pleural pressures on interstitial pressures in isolated dog lungs." Journal of Applied Physiology 70, no. 2 (February 1, 1991): 914–18. http://dx.doi.org/10.1152/jappl.1991.70.2.914.

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We report the first direct measurements of perialveolar interstitial pressures in lungs inflated with negative pleural pressure. In eight experiments, we varied surrounding (pleural) pressure in a dog lung lobe to maintain constant inflation with either positive alveolar and ambient atmospheric pleural pressures (positive inflation) or ambient atmospheric alveolar and negative pleural pressures (negative inflation). Throughout, vascular pressure was approximately 4 cmH2O above pleural pressure. By the micropuncture servo-null technique we recorded interstitial pressures at alveolar junctions (Pjct) and in the perimicrovascular adventitia (Padv). At transpulmonary pressure of 7 cmH2O (n = 4), the difference of Pjct and Pady from pleural pressure of 0.9 +/- 0.4 and -1.1 +/- 0.2 cmH2O, respectively, during positive inflation did not significantly change (P less than 0.05) after negative inflation. After increase of transpulmonary pressure from 7 to 15 cmH2O (n = 4), the decrease of Pjct by 3.3 +/- 0.3 cmH2O and Pady by 2.0 +/- 0.4 cmH2O during positive inflation did not change during negative inflation. The Pjct-Pady gradient was not affected by the mode of inflation. Our measurements indicate that, in lung, when all pressures are referred to pleural or alveolar pressure, the mode of inflation does not affect perialveolar interstitial pressures.

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Gravlee, G. P., S. D. Brauer, M. F. O'Rourke, and A. P. Avolio. "A Comparison of Brachial, Femoral, and Aortic Intra-Arterial Pressures before and after Cardiopulmonary Bypass." Anaesthesia and Intensive Care 17, no. 3 (August 1989): 305–11. http://dx.doi.org/10.1177/0310057x8901700311.

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Following recent evidence that brachial and femoral artery pressures are more reliable than radial artery pressures after cardiopulmonary bypass, thirty-one adults had simultaneous pre and post-bypass measurements of brachial, femoral, and ascending aortic pressures. Two minutes after cardiopulmonary bypass, brachial artery systolic pressure and mean arterial pressure fell significantly below corresponding pressures in the femoral artery and aorta. Five minutes after cardiopulmonary bypass, only brachial artery systolic pressure was still less than femoral and aortic systolic pressures. By ten minutes after bypass, all significant pressure differences had resolved except between brachial and femoral artery systolic pressures. Clinically significant (≥ 5 mmHg) aortic-to-brachial reductions in mean arterial pressures occurred in six (19%) patients at two minutes and in three (10%) patients at five and ten minutes after bypass. Equivalent aortic-to-femoral mean pressure diminution occurred in two (6%) patients at two minutes and one (3%) patient at five and ten minutes after bypass. Neither systemic vascular resistance nor body temperatures contributed significantly to post-bypass central-to-peripheral pressure reductions. Immediately following bypass, femoral artery pressures reproduce central aortic pressures more reliably than do radial or brachial artery pressures.

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Mendelowitz, D., and A. M. Scher. "Pulsatile pressure can prevent rapid baroreflex resetting." American Journal of Physiology-Heart and Circulatory Physiology 258, no. 1 (January 1, 1990): H92—H100. http://dx.doi.org/10.1152/ajpheart.1990.258.1.h92.

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In a previous study [Am. J. Physiol. 255 (Heart Circ. Physiol. 24): H673-H678, 1988] we demonstrated that baroreflex responses decay (reset) to increased static sinus pressures, but with increased pulsatile pressure, responses are maintained. To determine more conclusively whether pulsatile pressure prevents rapid baroreflex resetting in this study we examined resetting as shifts of the baroreflex (sinus pressure-arterial pressure) curve. In seven anesthesized rabbits the left sinus was vascularly isolated and conditioned for 5 min to static or pulsatile pressures of 60, 100, or 140 mmHg mean pressure, 0 or 35–40 mmHg pulse pressure. The baroreflex curve was then determined by stepwise changing sinus pressure from 40 to 160 mmHg in 20-mmHg increments. Threshold, midpoint, and saturation sinus pressures shifted 25-39% with static conditioning pressures but did not shift significantly with pulsatile pressures. Also, the baroreflex responses to step increases in static sinus pressure decayed, as resetting occurred, but did not decay with pulsatile sinus pressure increases. Thus the baroreflex rapidly resets with static pressures, but there is minimal, if any, resetting with pulsatile pressures.

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Fixler, David E., W. Pennock Laird, and Kent Dana. "Usefulness of Exercise Stress Testing for Prediction of Blood Pressure Trends." Pediatrics 75, no. 6 (June 1, 1985): 1071–75. http://dx.doi.org/10.1542/peds.75.6.1071.

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The purpose of this study was to determine whether values of blood pressure during exercise help predict which adolescents are prone to maintain high blood pressure. Dynamic and isometric exercise stress tests were performed on 131 adolescents who had had systolic or diastolic pressures greater than the 95th percentile on three examinations the previous year. Follow-up blood pressures were measured 1 year after the stress testing, and outcomes were classified on the basis of the blood pressure status that year. Stepwise regression analysis was used to examine the association between earlier blood pressures and exercise pressures with outcome pressures. In both male and female adolescents, the average resting systolic pressure on the earlier survey was the best predictor of systolic pressure 2 years later. Blood pressures and heart rates during dynamic and isometric exercise did not significantly contribute to the models' prediction of future systolic or diastolic pressures. The data suggest that exercise stress testing is not a valid method for predicting youths whose blood pressures will remain elevated over the next 1 to 2 years.

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Fike, C. D., and S. J. Lai-Fook. "Effect of airway and left atrial pressures on microcirculation of newborn lungs." Journal of Applied Physiology 69, no. 3 (September 1, 1990): 1063–72. http://dx.doi.org/10.1152/jappl.1990.69.3.1063.

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To determine the effect of lung inflation and left atrial pressure on the hydrostatic pressure gradient for fluid flux across 20- to 60-microns-diam venules, we isolated and perfused the lungs from newborn rabbits, 7-14 days old. We used the micropuncture technique to measure venular pressures in some lungs and perivenular interstitial pressures in other lungs. For all lungs, we first measured venular or interstitial pressures at a constant airway pressure of 5 or 15 cmH2O with left atrial pressure greater than airway pressure (zone 3). For most lungs, we continued to measure venular or interstitial pressures as we lowered left atrial pressure below airway pressure (zone 2). Next, we inflated some lungs to whichever airway pressure had not been previously used, either 5 or 15 cmH2O, and repeated venular or interstitial pressures under one or both zonal conditions. We found that at constant blood flow a reduction of left atrial pressure below airway pressure always resulted in a reduction in venular pressure at both 5 and 15 cmH2O airway pressures. This suggests that the site of flow limitation in zone 2 was located upstream of venules. When left atrial pressure was constant relative to airway pressure, the transvascular gradient (venular-interstitial pressures) was greater at 15 cmH2O airway pressure than at 5 cmH2O airway pressure. These findings suggest that in newborn lungs edema formation would increase at high airway pressures only if left atrial pressure is elevated above airway pressure to maintain zone 3 conditions.

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VERSI, E., LINDA CARDOZO, and D. J. COOPER. "Urethral Pressures: Analysis of Transmission Pressure Ratios." British Journal of Urology 68, no. 3 (September 1991): 266–70. http://dx.doi.org/10.1111/j.1464-410x.1991.tb15320.x.

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Dunstan, D. J., N. W. A. Van Uden, and G. J. Ackland. "High Pressure Instrumentation: Low and Negative Pressures." High Pressure Research 22, no. 3-4 (January 2002): 773–78. http://dx.doi.org/10.1080/08957950212441.

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Ruth, P. J. van, R. R. Hillis, and R. E. Swarbrick. "DETECTING OVERPRESSURE USING POROSITY-BASED TECHNIQUES IN THE CARNARVON BASIN, AUSTRALIA." APPEA Journal 42, no. 1 (2002): 559. http://dx.doi.org/10.1071/aj01032.

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Overpressure has been encountered in many wells drilled in the Carnarvon Basin. Sonic logs are used to estimate pore pressure in shales in the Carnarvon Basin using the Eaton and equivalent depth methods of estimating pore pressure from velocity data with reference to a normal compaction trend. The crux of pore pressure estimation from the sonic log lies in the determination of the normal compaction trend, i.e. the acoustic travel time (Δt)/depth (z) trend for normally pressured sediments. The normal compaction trend for shales in the Carnarvon Basin was established by fitting an Athy-type exponential relationship to edited sonic log data, and is: Δt = 225 + 391exp(-0.00103z) Vertical stress estimates are also needed for the Eaton and equivalent depth methods used herein. A vertical stress (σv) relationship was obtained by fitting a regression line to vertical stress estimates from the density log, and is: σv = 0.0131 z1.0642 The Eaton and equivalent depth methods yield similar pressure estimates. However, the equivalent depth method can only be applied over a limited range of acoustic travel times, a limitation that does not apply to the Eaton method. The pressure estimates from the Eaton method were compared to pressures measured by direct pressure tests in adjacent permeable units. There is a good correlation between Eaton and test pressures in normally pressured intervals in three wells and overpressured intervals in two wells. Eaton pressure estimates underestimate overpressured direct pressure measurements in four wells by up to 13 MPa. This is consistent with overpressure being generated (at least in part) by a fluid expansion mechanism or lateral transfer of overpressure. The Eaton pressures in one well are, on average, 11 MPa lower than hydrostatic pore pressure recorded in direct pressure measurements below the Muderong Shale. The sediments in this well appear to be overcompacted due to exhumation. Mud weights can be used as a proxy for pore pressure in shales where direct pressure measurements are not available in the adjacent sandstones. The Eaton pressure estimates are consistent with mud weight in the Gearle Siltstone and Muderong Shale in 4 of the 8 wells studied. The Eaton pressures are on average 10 Mpa in excess of mud weight in the Muderong Shale and Gearle Siltstone in three wells. It is unclear whether the predicted Eaton pressures in these three wells accurately reflect pore pressure (i.e. the mud weights do not accurately reflect pore pressure), or whether they are influenced by changes in shale mineralogy (because the gamma ray filter does not differentiate between shale mineralogy).

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Fike, C. D., S. J. Lai-Fook, and R. D. Bland. "Alveolar liquid pressures in newborn and adult rabbit lungs." Journal of Applied Physiology 64, no. 4 (April 1, 1988): 1629–35. http://dx.doi.org/10.1152/jappl.1988.64.4.1629.

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To study the effects of lung maturation and inflation on alveolar liquid pressures, we isolated lungs from adult and newborn rabbit pups (1-11 days old). We used the micropuncture technique to measure alveolar liquid pressure at several transpulmonary pressures on lung deflation. Alveolar liquid pressure was greater than pleural pressure but less than airway pressure at all transpulmonary pressures. Alveolar liquid pressure decreased further below airway pressure with lung inflation. At high transpulmonary pressure, alveolar liquid pressure was less in newborn than in adult lungs. To study the effects of edema, we measured alveolar liquid pressures in newborn lungs with different wet-to-dry weight ratios. Alveolar liquid pressure increased with progressive edema. In addition, we compared alveolar liquid and perivenular interstitial pressures in perfused newborn lungs and found that they were similar. Thus alveolar liquid pressure can be used to estimate perivenular interstitial pressure. We conclude that the transvascular pressure gradient for fluid flux into the interstitium might increase with lung inflation and decrease with progressive edema. Furthermore, this gradient might be greater in newborn than adult lungs at high inflation pressures.

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Varan, Nilufer Yildiz. "Wireless pressure sensors for pressure garments treated with chitosan." International Journal of Clothing Science and Technology 29, no. 5 (September 4, 2017): 732–42. http://dx.doi.org/10.1108/ijcst-12-2016-0136.

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Purpose The purpose of this paper is to analyze the effects of chitosan treatments on exerted pressures of nylon 6.6/elastane pressure garments in three different knit structures using wireless pressure sensors for an accurate and a precise scar management for future designs. Design/methodology/approach Pressure garments designed in different structures consist of 70/30 and 75/25 nylon 6.6/elastane were treated with chitosan and the exerted pressures were analyzed using wireless pressure sensors including ultra-thin and flexible printed circuit sensors in comparison with untreated control samples. Antimicrobial activities and washing tests were also evaluated. Findings It is found that chitosan treatments have a significant effect on final pressures. Exerted pressures increased significantly for all samples after chitosan treatments. Higher pressures were measured for weft knit structured designs while lower pressures were recorded for powernet structured garments. It is found that the elasticity showed a small significant decrease and it has attributed due to a small significant shrinkage during processes. The mean scores of pressures were found in the acceptable medical range which will continue to help hypertrophic scar management for future designs. The exerted pressures of the fabrics remained constant after five washes and showed a small significant decrease after 10 and 50 washes which will provide a long period of compression. Permanent antimicrobial effectiveness has gained at around 90 percent after five washes and 50 percent after 50 washes. A small significant increase was observed for stiffness (CD, MD) after ten washes. Originality/value Chitosan treatments impact exerted pressures of pressure garments significantly. It is a reference to evaluate pressure functions of pressure garments using wireless pressure sensors while imparting antimicrobial activity.

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Salem, M. Ramez, Keith W. Bruninga, Jyothi Dodlapatii, and Ninos J. Joseph. "Metoclopramide Does Not Attenuate Cricoid Pressure–induced Relaxation of the Lower Esophageal Sphincter in Awake Volunteers." Anesthesiology 109, no. 5 (November 1, 2008): 806–10. http://dx.doi.org/10.1097/aln.0b013e31818a37dc.

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Background The authors examined the influence of metoclopramide on cricoid pressure-induced relaxation of the lower esophageal sphincter (LES) in awake human volunteers. Methods With local institutional review board approval, measurements of LES and intragastric pressures were made in 10 consenting volunteers before cricoid pressure application, during 15 s of cricoid pressure application, and after release of cricoid pressure. The measurements were repeated after 0.15 mg/kg intravenous metoclopramide. Cricoid pressure was applied by one investigator trained to consistently apply a force of 44 N. Results Cricoid pressure resulted in immediate decrease in LES and barrier pressures from 14.1 +/- 2.9 mmHg to 3.2 +/- 3.7 mmHg and from 9.6 +/- 3.4 mmHg to -1.8 +/- 2.9 mmHg, respectively. These pressures promptly returned to baseline values after release of cricoid pressure. LES and barrier pressures increased after metoclopramide from 14.5 +/- 3.1 to 19.6 +/- 4.7 mmHg and from 10.2 +/- 3.6 to 14.1 +/- 5.5 mmHg, respectively. Cricoid pressure applied after metoclopramide resulted in immediate decreases in LES and barrier pressures to levels comparable to cricoid pressure before metoclopramide, but immediately returned to precricoid values after release of pressure. Conclusions The current investigation demonstrates that cricoid pressure reflexly decreases LES tone and barrier pressure in awake subjects. Although metoclopramide increased LES and barrier pressures, it did not attenuate cricoid pressure-induced relaxation of the LES and barrier pressures and thus seems to have no value in preventing gastroesophageal reflux during cricoid pressure. Metoclopramide may be useful in preventing reflux when there is need to release or discontinue cricoid pressure.

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Panthee, Suman. "Vertical and Horizontal Support Pressure Along The Kulekhani Iii Hep Tunnel Alignment, Nepal." Journal of Institute of Science and Technology 21, no. 1 (November 24, 2016): 112–18. http://dx.doi.org/10.3126/jist.v21i1.16062.

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Support pressure obtained in tunnel is considered as stresses for applied support. Therefore, estimation of support pressure in tunnel is important task for tunnel support design. Several equations are proposed to estimate support pressures. In this study, Barton equation was used for estimation support pressures along the tunnel of Kulekhani III HEP. The calculated support pressures were highly dependent on Q value and joint characteristics. Vertical and horizontal support pressures in the Marble and Quartzite followed the pattern as followed by Q but for other rocks support pressures were not only dependent on Q but had high influence of the joint characteristics. Support pressures obtained from the equation can also be used to estimate support pressure to some extent but modification is necessary. The equations can be considered for obtaining maximum support pressures for support design.Journal of Institute of Science and TechnologyVolume 21, Issue 1, August 2016, page: 112-118

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Aldea, G. S., H. Mori, W. K. Husseini, R. E. Austin, and J. I. E. Hoffman. "Effects of increased pressure inside or outside ventricles on total and regional myocardial blood flow." American Journal of Physiology-Heart and Circulatory Physiology 279, no. 6 (December 1, 2000): H2927—H2938. http://dx.doi.org/10.1152/ajpheart.2000.279.6.h2927.

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Increasing pressures to 30 mmHg in right (RV) and left (LV) ventricles and surrounding heart (SH) in isolated, arrested, maximally vasodilated, blood-perfused dog hearts shifted pressure-flow (PF) curves rightward and increased zero flow pressure (Pzf) by an amount equal to the RV applied pressure, SH applied pressure, or two-thirds of the LV applied pressure. There were comparable increases in coronary venous pressures. Increasing LV or SH pressures decreased coronary blood flows, especially in the subendocardium. Decreases in driving pressure decreased flows in all layers, but even with driving pressure of 5 mmHg, a few subepicardial pieces had flow. We conclude with the following: 1) raising pressures inside or outside the heart shifts PF curves and raises Pzfby increasing coronary venous pressure; 2) the effects are most prominent in the subendocardial muscle layer; and 3) as driving pressures are decreased, there is a range of Pzfin the heart with the final Pzfrecorded due to the last little piece of muscle to be perfused.

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Langner, Shannon. "Gauging their pressure: evaluating automated blood pressures over 30 minutes with standard office blood pressures." Evidence-Based Practice 22, no. 5 (May 2019): 3. http://dx.doi.org/10.1097/ebp.0000000000000413.

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Song, Zhixiang, and Junwen Zhang. "Progressive failure mechanical behaviour and response characteristics of sandstone under stress-seepage coupling." Journal of Geophysics and Engineering 18, no. 2 (March 15, 2021): 200–218. http://dx.doi.org/10.1093/jge/gxab008.

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Abstract Conventional triaxial loading tests with different confining pressures and stress-seepage coupling tests on sandstone with different confining pressures and seepage pressures were conducted. A permeability model considering strength and strain was established, which better characterized the progressive deformation mechanical behaviour of sandstone under stress-seepage coupling. The results showed the following. (i) The confining pressure not only affects the peak strength of sandstone but also affects the axial deformation under conventional triaxial loading conditions. (ii) Compared with the seepage pressure effect, the degree of the confining pressure effect on the strength of sandstone was weaker, but the degree of that on the axial, radial and volumetric deformations of sandstone was stronger under stress-seepage coupling. (iii) With increasing confining pressure, the axial strain of sandstone decreased, while the corresponding radial and volumetric strains showed progressively increasing evolution characteristics under identical seepage pressures and different confining pressures. With increasing seepage pressure, the axial strain continuously decreased, while the corresponding radial and volumetric strains showed the progressive evolution characteristic of first increasing and then decreasing under identical confining pressures and different seepage pressures. (iv) Compared with the confining pressure effect, the degree of the seepage pressure effect on the permeability progressive evolution law of sandstone was weaker under stress-seepage coupling. The research conclusions could enrich the theories for the prevention and control of water inrush accidents in coal mines.

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Tsai, M.-H., John D. Dow, and R. V. Kasowski. "InP under high pressures." Journal of Materials Research 7, no. 8 (August 1992): 2205–10. http://dx.doi.org/10.1557/jmr.1992.2205.

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The direct energy gaps, Eg, and the indirect gaps at the X point, E(X), of GaAs and AlxGa1−xAs alloys are essentially linear functions of hydrostatic pressure, P. Recent photoluminescence measurements of Tozer et al. for InP under high pressures, however, found that Eg(P) is not quite linear, but bends down slightly at high pressures. Using the first-principles pseudofunction method, we have calculated Eg and E(X) as functions of pressure, as well as the zero-temperature equation of state P(V). Our calculated gap curve for InP, Eg(P), bends down slightly, as found in photoluminescence studies. The slope dEg/dP is 8.8 meV/kbar for small pressures P, and is in good agreement with the experimental value, 8.32 meV/kbar. The observed nonlinearity in the dependence of Eg on pressure for InP is attributed to a large derivative of the bulk modulus with respect to pressure. The calculated bond length, bulk modulus, and critical pressure for a phase transition from the zinc blende to a rocksalt structure, and the unit cell volume change at this phase transition are all in good agreement with the data.

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Hakim, T. S., and S. Kelly. "Occlusion pressures vs. micropipette pressures in the pulmonary circulation." Journal of Applied Physiology 67, no. 3 (September 1, 1989): 1277–85. http://dx.doi.org/10.1152/jappl.1989.67.3.1277.

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Because of the discrepancies between the arterial and venous occlusion technique and the micropuncture technique in estimating pulmonary capillary pressure gradient, we compared measurements made with the two techniques in the same preparations (isolated left lower lobe of dog lung). In addition, we also obtained direct and reliable measurements of pressures in 0.9-mm arteries and veins using a retrograde catheterization technique, as well as a microvascular pressure made with the double-occlusion technique. The following conclusions were made from dog lobes perfused with autologous blood at normal flow rate of 500–600 ml/min and pressure gradient of 12 mmHg. 1) The double-occlusion technique measures pressure in the capillaries, 2) a small pressure gradient (0.5 mmHg) exists between 30- to 50-micron arteries and veins, 3) a large pressure gradient occurs in arteries and veins greater than 0.9 mm, 4) the arterial and venous occlusion techniques measure pressures in vessels that are less than 900 microns diam but greater than 50 microns, very likely close to 100 microns, 5) serotonin constricts arteries (larger and smaller than 0.9 mm) whereas histamine constricts veins (larger and smaller than 0.9 mm). Thus three different techniques (small retrograde catheter, arterial and venous occlusion, and micropuncture) show consistent results, confirming the presence of significant resistance in large arteries and veins with minimal resistance in the microcirculation.

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Fike, C. D., and M. R. Kaplowitz. "Effect of airway and left atrial pressures on microvascular and interstitial pressures in adult lungs." Journal of Applied Physiology 74, no. 5 (May 1, 1993): 2112–20. http://dx.doi.org/10.1152/jappl.1993.74.5.2112.

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The purpose of this study was to determine the effect of lung inflation and left atrial pressure on the hydrostatic pressure gradient for fluid flux across 20- to 80-microns-diam arterioles and venules in isolated perfused lungs of adult rabbits. We used the micropuncture technique and measured microvascular or interstitial pressures at constant airway pressures of 5 and 15 cmH2O with left atrial pressure adjusted above (zone 3 conditions) or below (zone 2 conditions) airway pressure. Only in lungs inflated to the higher airway pressure did a reduction in left atrial pressure below airway pressure result in concomitant reductions in venular pressure. This suggests that the site of flow limitation in zone 2 shifted from venules > 80 microns diam toward vessels <20 microns diam with inflation from 5 to 15 cmH2O. With the lungs under zone 3 conditions, both transarteriolar and transvenular gradients (microvascular-interstitial pressures) were greater at the higher compared with the lower airway pressure. In contrast, transarteriolar and transvenular gradients changed in opposite directions when compared at the two inflation pressures under zone 2 conditions. Counteracting changes in transmicrovascular gradients make it difficult to predict the effect on fluid filtration from lung inflation under zone 2 conditions. When zone 3 conditions are maintained during inflation, the tendency for edema formation should increase.

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Eisenhoffer, J., R. M. Elias, and M. G. Johnston. "Effect of outflow pressure on lymphatic pumping in vitro." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 1 (July 1, 1993): R97—R102. http://dx.doi.org/10.1152/ajpregu.1993.265.1.r97.

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The objective of this study was to determine how lymphatic vessels responded to outflow pressure changes in vitro. Bovine mesenteric lymphatics were suspended in an organ bath preparation with both inflow and outflow ends cannulated. Input to the duct was provided from a reservoir filled with Krebs solution. To initiate pumping, a transmural pressure was applied to the ducts by elevating the fluid reservoir and outflow catheters and making their heights equal to one another. The outflow catheter was then elevated above the liquid in the reservoir in 2-cmH2O increments, and pumping activity was monitored for 10 min at each outflow pressure. Outflow pressures were calculated as the product of the flow rate and outflow cannula resistance plus the height of the tip of the outflow catheter above the liquid in the organ bath. At low transmural pressures (2-4 cmH2O), elevations in outflow pressure often had little effect on flow rates until high outflow pressures had been attained. In contrast, elevations in outflow pressures resulted in an increasingly rapid decline in flow rates as transmural pressures were incrementally increased. The mean power (in mu W) required to produce the observed flow rate was estimated at each outflow pressure as the product of the flow rate and the pressure across the lymphatic vessel. The ability of the lymphatics to generate sustained or enhanced power output in response to an increasing outflow pressure challenge was most pronounced at lower transmural pressures. As transmural pressures were increased, the range of outflow pressures that stimulated increased power production was diminished. We conclude that elevations in outflow pressure in an in vitro preparation result in a nonlinear decline in flow rates. This nonlinearity is due to an active lymphatic pump mechanism.

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Dave, Jaydev K., Valgerdur G. Halldorsdottir, John R. Eisenbrey, Joel S. Raichlen, Ji-Bin Liu, Maureen E. McDonald, Kris Dickie, Shumin Wang, Corina Leung, and Flemming Forsberg. "Subharmonic microbubble emissions for noninvasively tracking right ventricular pressures." American Journal of Physiology-Heart and Circulatory Physiology 303, no. 1 (July 1, 2012): H126—H132. http://dx.doi.org/10.1152/ajpheart.00560.2011.

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Right heart catheterization is often required to monitor intra-cardiac pressures in a number of disease states. Ultrasound contrast agents can produce pressure modulated subharmonic emissions that may be used to estimate right ventricular (RV) pressures. A technique based on subharmonic acoustic emissions from ultrasound contrast agents to track RV pressures noninvasively has been developed and its clinical potential evaluated. The subharmonic signals were obtained from the aorta, RV, and right atrium (RA) of five anesthetized closed-chest mongrel dogs using a SonixRP ultrasound scanner and PA4-2 phased array. Simultaneous pressure measurements were obtained using a 5-French solid state micromanometer tipped catheter. Initially, aortic subharmonic signals and systemic blood pressures were used to obtain a calibration factor in units of millimeters of mercury per decibel. This factor was combined with RA pressures (that can be obtained noninvasively) and the acoustic data from the RV to obtain RV pressure values. The individual calibration factors ranged from −2.0 to −4.0 mmHg/dB. The subharmonic signals tracked transient changes in the RV pressures within an error of 0.6 mmHg. Relative to the catheter pressures, the mean errors in estimating RV peak systolic and minimum diastolic pressures, and RV relaxation [isovolumic negative derivative of change in pressure over time (−dP/d t)] by use of the subharmonic signals, were −2.3 mmHg, −0.8 mmHg, and 2.9 mmHg/s, respectively. Overall, acoustic estimates of RV peak systolic and minimum diastolic pressures and RV relaxation were within 3.4 mmHg, 1.8 mmHg, and 5.9 mmHg/s, respectively, of the measured pressures. This pilot study demonstrates that subharmonic emissions from ultrasound contrast agents have the potential to noninvasively track in vivo RV pressures with errors below 3.5 mmHg.

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Wang, Xiao Fei, and Yang Ping Wang. "The Conventional Triaxial Compressive Test of Plain Reactive Powder Concrete." Applied Mechanics and Materials 670-671 (October 2014): 401–6. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.401.

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Through the conventional triaxial test about plain reactive powder concrete under different confining pressures at 0Mpa, 25 Mpa,50 Mpa and 75 Mpa, this paper obtained the stress-strain curves in axial direction and radial direction of plain reactive powder concrete under different confining pressures, compared and analyzed the effects of confining pressures on peak strength, peak strain, Elastic modulus, Poisson ratio and failure modes of plain reactive power concrete also. The results showed that peak strength increases with the increase of confining pressure, when confining pressure increases from 0Mpa to 25Mpa, the peak strength increases most rapidly. The results also showed that peak strain increases linearly with the increase of confining pressure, when confining pressure increase from 0Mpa to 75Mpa gradually, the peak strain increases from 0.2 percent to 0.93 percent, meanwhile Poisson ratio increase with the increase of confining pressures, yet Elastic modulus changes slight at different confining pressures, failure modes of plain reactive powder concrete at different confining pressures exhibit different modes, when confining pressure is 0Mpa, failure mode presents as splitting failure, shear failure mode at 25Mpa, while shear failure merge local crushing at 50MPa and 75MPa.

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Mousavi, Seyed Nasrollah, Renato Steinke Júnior, Eder Daniel Teixeira, Daniele Bocchiola, Narjes Nabipour, Amir Mosavi, and Shahabodin Shamshirband. "Predictive Modeling the Free Hydraulic Jumps Pressure through Advanced Statistical Methods." Mathematics 8, no. 3 (March 2, 2020): 323. http://dx.doi.org/10.3390/math8030323.

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Pressure fluctuations beneath hydraulic jumps potentially endanger the stability of stilling basins. This paper deals with the mathematical modeling of the results of laboratory-scale experiments to estimate the extreme pressures. Experiments were carried out on a smooth stilling basin underneath free hydraulic jumps downstream of an Ogee spillway. From the probability distribution of measured instantaneous pressures, pressures with different probabilities could be determined. It was verified that maximum pressure fluctuations, and the negative pressures, are located at the positions near the spillway toe. Also, minimum pressure fluctuations are located at the downstream of hydraulic jumps. It was possible to assess the cumulative curves of pressure data related to the characteristic points along the basin, and different Froude numbers. To benchmark the results, the dimensionless forms of statistical parameters include mean pressures (P*m), the standard deviations of pressure fluctuations (σ*X), pressures with different non-exceedance probabilities (P*k%), and the statistical coefficient of the probability distribution (Nk%) were assessed. It was found that an existing method can be used to interpret the present data, and pressure distribution in similar conditions, by using a new second-order fractional relationships for σ*X, and Nk%. The values of the Nk% coefficient indicated a single mean value for each probability.

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Take, W. A., and A. J. Valsangkar. "Earth pressures on unyielding retaining walls of narrow backfill width." Canadian Geotechnical Journal 38, no. 6 (December 1, 2001): 1220–30. http://dx.doi.org/10.1139/t01-063.

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Arching theory predicts a significant reduction in earth pressures behind retaining walls of narrow backfill width. An extensive series of centrifuge tests has been performed to evaluate the use of flexible subminiature pressure cells in the centrifuge environment and their subsequent use to measure lateral earth pressures behind retaining walls of narrow backfill width. Although the flexible earth pressure cells exhibit hysteresis and nonlinear calibration behaviour, the extensive calibration studies indicate that stiff diaphragm type earth pressure cells may be used with replicate models to measure earth pressures. Measurements of lateral pressures acting on the unyielding model retaining walls show good agreement with Janssen's arching theory. Tests on backfills bounded by vertical planes of dissimilar frictional characteristics indicate arching theory with an average interface friction angle provides a reasonable estimate of lateral earth pressures.Key words: fascia retaining walls, silos, earth pressures, pressure cells, centrifuge modelling.

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26

Chaves, Paula, Daniela Simões, Maria Paço, Francisco Pinho, José Alberto Duarte, and Fernando Ribeiro. "Pressure Applied during Deep Friction Massage: Characterization and Relationship with Time of Onset of Analgesia." Applied Sciences 10, no. 8 (April 14, 2020): 2705. http://dx.doi.org/10.3390/app10082705.

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This study aims to determine if a dose–response relationship exists between the pressure applied during deep friction massage (DFM) and the time to the onset of analgesia in an asymptomatic patellar tendon. For this purpose, pressures applied by physiotherapists during DFM (study 1) were characterized and then, based on these pressures, the effects of different DFM pressures on the time to the onset of analgesia were assessed (study 2). First, the mean pressure applied by 40 physiotherapists during a DFM session was assessed with a pressure sensor through an observational, cross-sectional and analytical study. Next, the effects of different pressure intensities (the median, the percentile 25 (P25), and the percentile 75 (P75) of the mean pressure obtained in study 1) were studied in a crossover trial enrolling 30 participants with an asymptomatic patellar tendon. A pressure sensor was used to register the pressures applied during DFM. Our main results indicated that the physiotherapists applied pressures with a wide variation ((mean pressure: 2.317 kg/cm2 (P25: 1.022 kg/cm2; P75: 4.161 kg/cm2)). It was also shown that higher pressures had shorter times to the onset of analgesia (pressure: 1 kg/m2, time to the onset of analgesia: 67.0 s (P25: 84.5 s; P75: 113.5 s); pressure: 2.3 kg/m2, time to the onset of analgesia: 59.0 s (P25: 73.5 s; P75: 87.3 s); pressure: 4.2 kg/m2, time to the onset of analgesia: 37.8 s (P25: 54.0 s; P75: 62.0 s)) (p ≤ 0.001). In conclusion, the mean DFM pressure obtained by the physiotherapists was 2.3 kg/cm2 (P25: 1.02 kg/cm2; P75: 4.16 kg/cm2). Higher pressures of DFM resulted in shorter times to the onset of analgesia.

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27

Zhong, Xing-Fu, and Zhi-Jing Chen. "Variational principles for topological pressures on subsets." Nonlinearity 36, no. 2 (January 5, 2023): 1168–91. http://dx.doi.org/10.1088/1361-6544/acadca.

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Abstract In this paper, we investigate the relations between various types of topological pressures and different versions of measure-theoretical pressures. We extend Feng–Huang’s variational principle for packing entropy to packing pressure and obtain two new variational principles for Pesin–Pitskel and packing pressures respectively. We show that various types of Katok pressures for an ergodic measure with respect to a potential function are equal to the sum of measure-theoretic entropy of this measure and the integral of the potential function. Moreover, we obtain Billingsley type theorem for packing pressure, which indicates that packing pressure can be determined by measure-theoretic upper local pressure of measures, and a variational principle for packing pressure of the set of generic points for any invariant ergodic Borel probability measure.

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28

Dou, Yi Hua, Yin Ping Cao, Fu Xiang Zhang, and Xiang Tong Yang. "Analysis of Influence to the Connect and Seal Ability of Tubing Connection of Inner Pressures." Advanced Materials Research 503-504 (April 2012): 790–93. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.790.

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To know the stress distribution of tubing connections with varied inner pressures for further understanding of the influence of pressures to the connection and seal ability, finite element model of API tubing connection was established and the Von Mises stresses and contact pressures of tubing connection was analyze by full make-up torque and varied inner pressures with nonlinear finite element method. It was found that the contact pressures and stresses on engagement threads may be increased with limited inner pressure. Meanwhile, stresses of engagement threads on both ends increased more sharply than others. And plastic deformation even breakage of engagement threads may occur if the inner pressure exceeds 70MPa

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29

Moulton, N. E., S. A. Wolf, E. F. Skelton, D. H. Liebenberg, T. A. Vanderah, A. M. Hermann, and H. M. Duan. "Pressure dependence ofTcinTl2Ba2CaCu2O8at hydrostatic pressures to 6 GPa." Physical Review B 44, no. 22 (December 1, 1991): 12632–34. http://dx.doi.org/10.1103/physrevb.44.12632.

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30

Giele, Henk, Katrina Liddiard, Kris Booth, and Fiona Wood. "Anatomical Variations in Pressures Generated by Pressure Garments." Plastic and Reconstructive Surgery 101, no. 2 (February 1998): 399–406. http://dx.doi.org/10.1097/00006534-199802000-00021.

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31

Ashraf, A., JM Conil, B. Georges, H. Gonzalez, P. Cougot, and K. Samii. "Relation between ventilatory pressures and intra-abdominal pressure." Critical Care 12, Suppl 2 (2008): P324. http://dx.doi.org/10.1186/cc6545.

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32

Christensen, Niels E., Arthur L. Ruoff, and C. O. Rodriguez. "Pressure strengthening: A way to multimegabar static pressures." Physical Review B 52, no. 13 (October 1, 1995): 9121–24. http://dx.doi.org/10.1103/physrevb.52.9121.

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33

Miao, Isaac, Robert Jee, and Christopher L. Pysyk. "Under pressure: an audit of airway device pressures." Canadian Journal of Anesthesia/Journal canadien d'anesthésie 65, no. 6 (January 10, 2018): 726–27. http://dx.doi.org/10.1007/s12630-018-1053-y.

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34

Kettenbeil, C., Z. Lovinger, S. Ravindran, M. Mello, and G. Ravichandran. "Pressure-Shear Plate Impact Experiments at High Pressures." Journal of Dynamic Behavior of Materials 6, no. 4 (June 17, 2020): 489–501. http://dx.doi.org/10.1007/s40870-020-00250-y.

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35

Macintyre, Lisa, and Rhona Ferguson. "Pressure garment design tool to monitor exerted pressures." Burns 39, no. 6 (September 2013): 1073–82. http://dx.doi.org/10.1016/j.burns.2013.05.012.

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36

Groothuis, Jan T., Linda van Vliet, Miriam Kooijman, and Maria T. E. Hopman. "Venous cuff pressures from 30 mmHg to diastolic pressure are recommended to measure arterial inflow by plethysmography." Journal of Applied Physiology 95, no. 1 (July 2003): 342–47. http://dx.doi.org/10.1152/japplphysiol.00022.2003.

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Venous occlusion strain gauge plethysmography (VOP) is based on the assumption that the veins are occluded and arterial inflow is undisturbed by the venous cuff pressure. Literature is not clear concerning the pressure that should be used. The purpose of this study was to determine the optimal venous occlusion pressure at which the highest arterial inflow is achieved in the forearm, calf, and leg by using VOP. We hypothesized that, for each limb segment, an optimal (range of) venous cuff pressure can be determined. Arterial inflow in each limb segment was measured in nine healthy individuals by VOP by using pressures ranging from 10 mmHg up to diastolic blood pressure. Arterial inflows were similar at cuff pressures between 30 and 60 mmHg for the forearm, leg, and calf. Arterial inflow in the forearm was significantly lower at 10 mmHg compared with the other cuff pressures. In addition, arterial inflows at 20 mmHg tended to be lower in each limb segment than flow at higher cuff pressures. In conclusion, no single optimum venous cuff pressure, at which a highest arterial inflow is achieved, exists, but rather a range of optimum cuff pressures leading to a similar arterial inflow. Venous cuff pressures ranging from 30 mmHg up to diastolic blood pressure are recommended to measure arterial inflow by VOP.

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37

Godbey, P. S., J. A. Graham, R. G. Presson, W. W. Wagner, and T. C. Lloyd. "Effect of capillary pressure and lung distension on capillary recruitment." Journal of Applied Physiology 79, no. 4 (October 1, 1995): 1142–47. http://dx.doi.org/10.1152/jappl.1995.79.4.1142.

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To investigate the effect of capillary pressure and alveolar distension on capillary recruitment, we used video-microscopy to quantify capillary recruitment in individual subpleural alveolar walls. Canine lobes were perfused with autologous blood either while inflated by positive airway pressure or while inflated by negative intrapleural pressure in the intact thorax with airway pressure remaining atmospheric. Low flow rates minimized the arteriovenous pressure gradient (< 5 mmHg), permitting capillary pressure estimation by averaging these pressures. Capillary pressure was varied stepwise from airway pressure to 30 mmHg above airway pressure. Capillary recruitment always began as capillary pressure exceeded airway pressure. At low positive airway pressures, the capillaries of the excised lobes opened suddenly over a narrow pressure range. AT higher airway pressures and in the intact thorax, recruitment occurred over a wide range of capillary pressures. We conclude that capillary perfusion begins when intracapillary pressure just exceeds alveolar pressure but that further increases in capillary pressure recruit capillaries depending on tension in the alveolar wall, whether imposed by positive airway pressure or by gravity when the lung is suspended in an intact thorax.

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38

Kimura, Tatsuto, Masahiro Masuko, Naoki Fujii, Hideki Kaida, and Naoto Kihara. "NUMERICAL AND HYDRAULIC EXPERIMENTS ON BORE PRESSURE DUE TO TSUNAMI." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 18. http://dx.doi.org/10.9753/icce.v36.currents.18.

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The 2011 Tohoku earthquake tsunami struck a wide area of the northeastern coast of Japan, and many coastal structures and buildings were damaged by the tsunami. Most of the buildings were damaged by the tsunami wave pressure. After the tsunami, characteristics of tsunami waive pressures have been investigated by many researcher, and are being clarified. As shown in previous studies, there are three regimes charactering the vertical pressure profiles. The first one is the impulsive pressure, which is observed just after the tsunami-bore impacted structures. In this regime, strong hydrodynamic pressures are generated by the fluid-solid impact process. After that, the bore pressure is observed, and both the hydrodynamic and hydrostatic pressures contribute the pressure profile. After that, the flow near the structures reaches a quasi-steady state, and the pressure profile becomes hydrostatic. Most of the evaluation equations of tsunami wave pressure proposed by the previous studies can be used against the impulsive pressures and the pressures in the quasi-steady-state regime. On the other hand, the characteristics and quantitative evaluations of the bore pressure remain immature. In this study, in order to clarify the characteristics of the bore pressure, experiments on the bore pressure are carried out, and furthermore, three-dimensional numerical simulations are also carried out.

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39

Feng, Yaoguang, Hongxun Hao, Yiqing Chen, Na Wang, Ting Wang, and Xin Huang. "Enhancement of Crystallization Process of the Organic Pharmaceutical Molecules through High Pressure." Crystals 12, no. 3 (March 20, 2022): 432. http://dx.doi.org/10.3390/cryst12030432.

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The enhancement of the crystallization process through high pressures was studied by using ribavirin (RVB) as a model compound. The effects of high pressure on crystallization thermodynamics, nucleation kinetics, and process yield were evaluated and discussed. The solubility of ribavirin in three pure solvents was measured at different pressures from 283.15 to 323.15 K. The results indicate that the solubility data of ribavirin decreased slightly when pressure was increased. The induction time of the cooling crystallization of ribavirin under different pressures was measured. The results show that high pressure could significantly reduce the nucleation induction period. Furthermore, the nucleation kinetic parameters under different pressures were calculated according to the classical nucleation theory. The effect of high pressure on the anti-solvent crystallization of ribavirin was also studied.

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40

SMITH, ANDREW M. "NEGATIVE PRESSURE GENERATED BY OCTOPUS SUCKERS: A STUDY OF THE TENSILE STRENGTH OF WATER IN NATURE." Journal of Experimental Biology 157, no. 1 (May 1, 1991): 257–71. http://dx.doi.org/10.1242/jeb.157.1.257.

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The decrease in hydrostatic pressure generated by octopus suckers adhering to wettable and non-wettable surfaces was measured using a flush-mounted miniature pressure transducer. The cavitation thresholds, or lowest sustainable pressures, of sea water on the same surfaces were also measured and were compared with the pressures generated by octopuses. It is shown that suckers can generate hydrostatic pressures below OMPa on moderately wettable surfaces. This disprovesthe commonly repeated assumption that suckers cannot produce pressures below a vacuum and suggests that the importance of suction in attachment mechanisms may have been overlooked. On epoxy, the lowest recorded pressure was −0.168MPa (0.268MPa or 2.66atm below ambient), and the octopus generated negative pressure in 35% of the pulls that were considered maximal efforts. The suckers never generated negative pressures on non-wettable surfaces. These results are in agreement with the range of pressures that sea water can sustain on the same surfaces. It is suggested, therefore, that cavitation, the failure of water in tension, limits the attachment force of suckers. The difference between the cavitation threshold of water in nature and the cavitation threshold of pure water is discussed.

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41

Miller, Larry S., Joseph K. Kim, Qing Dai, Jyothi Mekapati, James Izanec, Chan Chung, Ji-Bin Liu, et al. "Mechanics and hemodynamics of esophageal varices during peristaltic contraction." American Journal of Physiology-Gastrointestinal and Liver Physiology 287, no. 4 (October 2004): G830—G835. http://dx.doi.org/10.1152/ajpgi.00015.2004.

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Our hypothesis states that variceal pressure and wall tension increase dramatically during esophageal peristaltic contractions. This increase in pressure and wall tension is a natural consequence of the anatomy and physiology of the esophagus and of the esophageal venous plexus. The purpose of this study was to evaluate variceal hemodynamics during peristaltic contraction. A simultaneous ultrasound probe and manometry catheter was placed in the distal esophagus in nine patients with esophageal varices. Simultaneous esophageal luminal pressure and ultrasound images of varices were recorded during peristaltic contraction. Maximum variceal cross-sectional area and esophageal luminal pressures at which the varix flattened, closed, and opened were measured. The esophageal lumen pressure equals the intravariceal pressure at variceal flattening due to force balance laws. The mean flattening pressures (40.11 ± 16.77 mmHg) were significantly higher than the mean opening pressures (11.56 ± 25.56 mmHg) ( P ≤ 0.0001). Flattening pressures >80 mmHg were generated during peristaltic contractions in 15.5% of the swallows. Variceal cross-sectional area increased a mean of 41% above baseline (range 7–89%, P < 0.0001) during swallowing. The peak closing pressures in patients that experience future variceal bleeding were significantly higher than the peak closing pressures in patients that did not experience variceal bleeding ( P < 0.04). Patients with a mean peak closing pressure >61 mmHg were more likely to bleed. In this study, accuracy of predicting future variceal bleeding, based on these criteria, was 100%. Variceal models were developed, and it was demonstrated that during peristaltic contraction there was a significant increase in intravariceal pressure over baseline intravariceal pressure and that the peak intravariceal pressures were directly proportional to the resistance at the gastroesophageal junction. In conclusion, esophageal peristalsis in combination with high resistance to blood flow through the gastroesophageal junction leads to distension of the esophageal varices and an increase in intravariceal pressure and wall tension.

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42

Sun, Wei Ming, Shui Sheng Chen, and Li Qun Tu. "Effect of Contact Pressure and Cyclic Stress Amplitude on Fretting Fatigue of 45-Carbon Steel." Key Engineering Materials 353-358 (September 2007): 134–37. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.134.

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The effect of contact pressure on fretting fatigue in quenched and tempered 45-carbon steel is studied. With an increase in contact pressure, fretting fatigue life is decreased quickly at low contact pressures; however it almost unchanged at high contact pressures. With an increase in cyclic stress amplitude, fretting fatigue life decreased. In the test, concavity is formed at the fretted area accompanying wear. The main crack is initiated at the outer edge corner of the concavity at high contact pressures, and initiated at the middle portion of the fretted area at low contact pressures.

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Orasanu, Judith, and Barry Strauch. "Temporal Factors in Aviation Decision Making." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 38, no. 14 (October 1994): 935–39. http://dx.doi.org/10.1177/154193129403801431.

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Time pressure has been found to reduce the quality of decision making by restricting consideration of information and options and by inducing strategy shifts. Time pressure is usually considered an external variable manipulated by the experimenter. In this paper we distinguish between externally-induced time pressures and crew-generated time pressures, and examine how crews can mitigate or exacerbate external pressures. The roles of both types of time pressures in crew decision making are examined in three air transport accidents and in crew performance in full-mission simulated flight. Implications for crew training are discussed.

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Nellis, S. H., and L. Whitesell. "Phasic pressures and diameters in small epicardial veins of the unrestrained heart." American Journal of Physiology-Heart and Circulatory Physiology 257, no. 4 (October 1, 1989): H1056—H1061. http://dx.doi.org/10.1152/ajpheart.1989.257.4.h1056.

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Previous data from this laboratory have revealed a large pressure pulse in small veins on the epicardial surface of the right ventricle of the rabbit. The phasic relationship between venule pressures and venule diameters in a beating heart was examined. Luminal pressures were measured in 39 different veins on the epicardial surface of the rabbit right ventricle. The venous luminal pressures averaged 12.6 mmHg maximum and 1.0 mmHg minimum. Pressures in 23 different small veins were also obtained at different right ventricular afterloads. Peak venous pressures increased with peak right ventricular pressure. The phasic diameter changes of 119 different vessels were examined. Vessel diameters decreased as luminal pressures increased. The average change in vessel diameter through a cardiac cycle was 20%, with a range from 0 to 60%. The large pulse pressures found in small veins appear to be related to decreasing vessel diameters and probably result from the displacement of blood as the vessels narrow.

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Miller, J. D., D. F. Peeler, J. Pattisapu, and A. D. Parent. "Supratentorial pressures: Part I: Differential intracranial pressures." Neurological Research 9, no. 3 (September 1987): 193–97. http://dx.doi.org/10.1080/01616412.1987.11739794.

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Shankar, Venkat, Kevin Churchwell, and Jayant Deshpande. "Peak pressures or plateau pressures in asthma." Intensive Care Medicine 33, no. 1 (October 26, 2006): 204. http://dx.doi.org/10.1007/s00134-006-0424-y.

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47

Grzesik, Zbigniew, Anna Kaczmarska, and Stanisław Mrowec. "Nonstoichiometry and Chemical Diffusion in Co₃O₄ Cobalt Oxide." Solid State Phenomena 227 (January 2015): 421–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.421.

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Nonstoichiometry and chemical diffusion in Co3O4oxide have been studied as a function of temperature (973-1173 K) and oxygen pressure (30-105Pa), using thermogravimetric techniques. It has been found that at very low oxygen pressures, close to the dissociation pressure of the oxide, interstitial cations and quasi-free electrons are the predominant point defects, while at high pressures cation vacancies and electron holes predominate. This behaviour is reflected in complex dependence of the deviation from stoichiometry, y, in the Co3±yO4oxide on oxygen pressure. At low pressures, namely, deviation from stoichiometry decreases with increasing oxygen pressure, reaching virtually constant value in intermediate pressures and increases at highest pressure range. Finally, these data as well as the results of kinetic rate measurements of Co3±yO4formation have been utilized in calculating the chemical diffusion coefficient as a function of temperature.

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48

Eisenhoffer, J., S. Lee, and M. G. Johnston. "Pressure-flow relationships in isolated sheep prenodal lymphatic vessels." American Journal of Physiology-Heart and Circulatory Physiology 267, no. 3 (September 1, 1994): H938—H943. http://dx.doi.org/10.1152/ajpheart.1994.267.3.h938.

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The objective of this study was to determine how isolated sheep prenodal popliteal lymphatic vessels responded to transmural and outflow pressure changes. Afferent lymphatics (0.5-1.0 mm diameter) were suspended in an organ bath with both inflow and outflow ends cannulated. Input to the duct was provided from a reservoir filled with Krebs solution. Two types of experiments were performed. In one group, a transmural pressure was applied to the ducts. In a second group of studies, the inflow pressure was fixed (at 2, 4, or 6 cmH2O) and the outflow pressure was increased in 4-cmH2O increments. The transmural pressure-flow relationship was expressed as a bell-shaped curve with pumping increasing up to 18-26 cmH2O and declining at higher pressures. Maximum flow rates averaged 1.4 +/- 0.6 ml/10 min. Greater than 50% of maximum pumping activity was available between approximately 12 and 43 cmH2O. In response to outflow pressures, variable responses were observed. In some vessels, elevations of outflow pressure had little impact on flow rates, until high outflow pressures were attained. In other ducts, pumping declined in response to outflow pressure challenge. With lower inflow pressures (2 or 4 cmH2O), flow rates occasionally increased with elevations of the outflow catheter. In ducts preset with inflow pressures of 6 cmH2O, the mean stop-flow pressure was 60 +/- 4.6 cmH2O. In comparison with previously published data on the pressure-flow relationships in postnodal lymphatics, prenodal vessels pumped over a larger range of transmural or outflow pressures.

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Glucksberg, M. R., and J. Bhattacharya. "Effect of vascular pressure on interstitial pressures in the isolated dog lung." Journal of Applied Physiology 75, no. 1 (July 1, 1993): 268–72. http://dx.doi.org/10.1152/jappl.1993.75.1.268.

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We report the first direct measurements of the effect of pulmonary vascular pressures on perialveolar interstitial pressures. In seven experiments we varied the intravascular pressure (Pvas) in isolated dog lungs held at constant airway pressure (PA). By the micropuncture servo-null technique, we recorded perialveolar interstitial pressures with respect to pleural pressure (0 cmH2O) at the alveolar junctions (Pjct) and in microvascular adventitia (Padv). At PA = 7 cmH2O, increase from 5 to 15 cmH2O did not affect Pjct, although it decreased Padv by 1.2 +/- 0.4 cmH2O. The Pjct-Padv gradient increased by 77%. Increasing Pvas to 25 cmH2O had no further effect on either interstitial pressure. In four experiments we also determined interstitial pressure in the hilum (Phil). When Pvas was increased from 5 to 15 cmH2O, Phil increased by 4.5 +/- 0.9 cmH2O. Further elevation of Pvas to 25 cmH2O increased Phil further by 2.4 +/- 0.4 cmH2O. At PA = 15 cmH2O, all interstitial pressures decreased, but their responses to Pvas were similar. We conclude that increase of Pvas 1) increases Phil but not perialveolar interstitial pressures and 2) increases the perialveolar interstitial pressure gradient, which may promote local liquid clearance.

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50

Lê Vũ Ngọc, Thanh, Bích Phạm Thị Ngọc, Uyên Nguyễn Đình Hoàng, and Nguyên Lê Thành Thái. "The Determination of Pressures toward Fraudulent Behavior on Financial Statements of Vietnamese Listed Companies." JOURNAL OF ASIAN BUSINESS AND ECONOMIC STUDIES 33, no. 8 (August 1, 2022): 121–40. http://dx.doi.org/10.24311/jabes/2022.33.08.08.

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The study focuses on understanding the pressures leading to fraudulent behavior on the financial statements of companies listed on the Vietnamese stock markets. First, the study identifies the pressures affecting fraudulent financial reporting behavior one by one, then turn to the interactive effects of the pressures on the behavior of corporate. The regression results of 2831 samples from 2014 to 2020 show that the pressure of maintaining the position of a large enterprise, the pressure of strictly complying with debt covenants, a profit pressure or reward incentive make managers commit financial statement fraud, and, if an enterprise is under a plethora of pressures at the same time, it will increase the fraudulent financial reporting behavior.

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Journal articles on the topic 'Pressures'

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