Gas bubble transport and emissions for shallow peat from a northern peatland: The role of pressure changes and peat structure

2015 ◽  
Vol 51 (1) ◽  
pp. 151-168 ◽  
Author(s):  
Xi Chen ◽  
Lee Slater
Keyword(s):  
Gas Bubble ◽  
Bubble Transport ◽  
Pressure Changes

scholarly journals Induction of Changes in Internal Gas Pressure of Bulky Plant Organs by Temperature Gradients

1990 ◽  
Vol 115 (2) ◽  
pp. 308-312 ◽  
Author(s):  
Kenneth A. Corey ◽  
Zhi-Yi Tan
Keyword(s):  
Bath Temperature ◽  
Ideal Gas ◽  
Gas Pressure ◽  
Temperature Gradients ◽  
Maximum Pressure ◽  
Plant Organs ◽  
Ideal Gas Law ◽  
Increasing Temperature ◽  
Pressure Changes

Water manometers were connected to fruits of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.), and then fruits were submerged in water baths providing initial temperature gradients between fruit and water of 0 to 19C. Apple (Malus domestics Borkh.) fruits, carrot (Daucus carota L.) roots, witloof chicory (Cichorium intybus L.) roots, rhubarb Rheum rhabarbarum L.) petioles, and pokeweed (Phytolacca americana L.) stems were subjected to water bath temperature gradients of 5C. Internal partial vacuums developed in all organs within minutes of imposing the gradients. The maximum partial vacuums in tomato and pepper fruits increased with increasing temperature gradients. Uptake of water accompanied changes in internal pressure reaching maxima of 17% (w/w) and 2% (w/w) of pepper and tomato fruits, respectively, after 22 hours. Maximum pressure changes achieved in bulky organs deviated from those predicted by the ideal gas law, possibly due to concomitant changes in gas pressure upon replacement of intercellular spaces with water and dissolution of CO2. Partial vacuums also developed in pepper fruits, rhubarb petioles, and pokeweed stems following exposure to air 15C cooler than initial organ temperatures. Results point to the role of temperature gradients in the transport of liquids and gases in plant organs.

The role of sediment structure in gas bubble storage and release

2016 ◽  
Vol 121 (7) ◽  
pp. 1992-2005 ◽  
Author(s):  
L. Liu ◽  
J. Wilkinson ◽  
K. Koca ◽  
C. Buchmann ◽  
A. Lorke
Keyword(s):  
Gas Bubble ◽  
Sediment Structure

Role of the Gonads in Control of Blood Pressure in Chickens

1957 ◽  
Vol 190 (1) ◽  
pp. 54-56 ◽  
Author(s):  
Robert K. Ringer ◽  
P. D. Sturkie ◽  
H. S. Weiss
Keyword(s):  
Blood Pressure ◽  
Sex Difference ◽  
Ovarian Activity ◽  
Adult Chicken ◽  
Sexual Stimulation ◽  
Gonadotrophin Secretion ◽  
Pressure Changes

Blood pressure changes in gonadectomized and gonadotrophin-treated chicks were utilized to determine the role of the gonads in establishing and maintaining the sex difference in pressure of the adult chicken. By the 23rd week, 4–5 weeks after the normal rise in male pressure, both capon and poulard pressures had climbed to near the male level and significantly above the female. This confirms that androgen is not essential to the rise in pressure, and indicates that other than ovarian activity, nothing inherent in the female prevents the rise. Furthermore, elevated poulard pressures could be depressed to near female levels with estrogen or 2-amino,5-nitrothiazole, presumably through suppression of pituitary gonadotrophin secretion. Exogenous gonadotrophin failed to change the pressure of the chick prematurely, despite marked sexual stimulation, suggesting that chronological maturation, possibly independent of the pituitary-gonad interrelationship, is a prerequisite.

The Pressure Sensitivity of Marine Invertebrates—a résumé after 25 years

1972 ◽  
Vol 73 ◽  
pp. 287-299 ◽  
Author(s):  
Elfed Morgan
Keyword(s):  
Marine Invertebrates ◽  
Surface Film ◽  
Pressure Sensitivity ◽  
Ecological Role ◽  
Tidal Amplitude ◽  
Pressure Sense ◽  
Pressure Changes

SynopsisEarly investigations into the effects of pressure on marine invertebrates were concerned mainly with determining limits of tolerance to extreme pressures, but within the last 25 years it has gradually emerged that many invertebrates are sensitive to quite small changes in pressure, often less than one atmosphere (1000 mb). The responses of most planktonic animals appear to be of a depth regulatory nature but certain littoral organisms show rhythmic changes in activity in response to cyclical pressure changes of tidal amplitude and frequency. The ecological role of such responses is considered.The parameters of the pressure sense are known only from behavioural studies and offer little information concerning the process of reception. A possible mechanism of transduction based on the compression of a surface film of gas is described.

The role of brain acetylcholine in GABAA receptor antagonist-induced blood-pressure changes in rat

1996 ◽  
Vol 317 (2-3) ◽  
pp. 301-307 ◽  
Author(s):  
Tahir Tellioǧlu ◽  
Serap Akin ◽  
Uǧur Özkutlu ◽  
Şule Oktay ◽  
Filiz Onat
Keyword(s):  
Blood Pressure ◽  
Receptor Antagonist ◽  
Gabaa Receptor ◽  
Gabaa Receptor Antagonist ◽  
Pressure Changes ◽  
Brain Acetylcholine

Intracranial Pressure at High Altitude and Acute Mountain Sickness

1995 ◽  
Vol 89 (2) ◽  
pp. 201-204 ◽  
Author(s):  
A. D. Wright ◽  
C. H. E. Imray ◽  
M. S. C. Morrissey ◽  
R. J. Marchbanks ◽  
A. R. Bradwell
Keyword(s):  
Intracranial Pressure ◽  
High Altitude ◽  
Acute Hypoxia ◽  
Acute Mountain Sickness ◽  
Raised Intracranial Pressure ◽  
Rapid Ascent ◽  
Mountain Sickness ◽  
Pressure Changes ◽  
Serial Measurements

1. Raised intracranial pressure has been noted in severe forms of acute mountain sickness and high-altitude cerebral oedema, but the role of intracranial pressure in the pathogenesis of mild to moderate acute mountain sickness is unknown. 2. Serial measurements of intracranial pressure were made indirectly by assessing changes in tympanic membrane displacement in 24 healthy subjects on rapid ascent to 5200 m. 3. Acute hypoxia at 3440 m was associated with a rise in intracranial pressure, but no difference was found in pressure changes at 4120 or 5200 m in subjects with or without symptoms of acute mountain sickness. 4. Raised intracranial pressure, though temporarily associated with acute hypoxia, is not a feature of acute mountain sickness with mild or moderate symptoms.

Wellbore Failure During Water-Alternating-Gas Injection by Use of Flow-Stress Coupling Method

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 172-183 ◽  
Author(s):  
Mahmood Bataee ◽  
Sonny Irawan ◽  
Syahrir Ridha ◽  
Hamed Hematpour ◽  
Zakaria Hamdi
Keyword(s):  
Coupling Method ◽  
Injection Wells ◽  
Iterative Coupling ◽  
Water Alternating Gas ◽  
Porosity And Permeability ◽  
Volume Method ◽  
Pressure Changes ◽  
Wellbore Failure

Summary Accurate evaluation of failure pressure is crucial in the design of injection wells. Besides, in-situ stresses play an important role in obtaining the results. Pressure and rock stresses are related together as the role of effective-stress theorem. In fact, pressure changes with stress alteration caused by change in porosity and permeability. Therefore, it should be obtained with the coupling method. Moreover, to calculate pressure, temperature, and stress in the fully coupling method, a huge matrix should be solved, and it takes long processing time to implement it. Therefore, this study developed a wellbore geomechanical model for stability during injection by use of the iterative coupling method. The processing speed was enhanced in this study because the parameters were calculated separately. The parameters of pressure, temperature, saturation, and stress were obtained for the multiphase-flow condition with numerical modeling. Furthermore, in this study, the finite-difference method (FDM) had been used to solve pressure, temperature, and saturation, whereas the finite-volume method (FVM) was applied to solve the wellbore stress. On top of that, the iterative coupling method was used to improve the accuracy of the stress results. As a result, a correction of approximately 20 psi (0.14 MPa) was noted for pressure in relation to stress, which is 1 psi (6.89 kPa). Moreover, the Drucker-Prager failure criterion was used to model the fracturing on the basis of the stress results. Other than that, sensitivity analysis on horizontal maximum (σH) and minimum (σh) stresses showed that by increasing σH, the maximum injection pressures to avoid fracturing had been reduced, whereas in the case for σh, an increment was observed.

The subfornical organ and relaxin-induced inhibition of reflex milk ejection in lactating rats

1987 ◽  
Vol 115 (2) ◽  
pp. 347-353 ◽  
Author(s):  
A. J. S. Summerlee ◽  
K. T. O'Byrne ◽  
S. A. Jones ◽  
L. Eltringham
Keyword(s):  
Cerebrospinal Fluid ◽  
Subfornical Organ ◽  
Behavioural Response ◽  
Milk Ejection ◽  
Blood Brain ◽  
Radiofrequency Lesions ◽  
Pressure Changes ◽  
And Control

ABSTRACT Experiments were carried out on anaesthetized, lactating rats to investigate the possible role of the subfornical organ in mediating relaxin-induced inhibition of reflex milk ejection. Milk ejection was judged by the behavioural response of the sucklings and by transient rises in intramammary pressure. Radiofrequency lesions of the subfornical organ, or control lesions in adjacent areas of the cerebrum, did not affect the pattern or the magnitude of intramammary pressure changes at reflex milk ejection. Purified porcine relaxin given by either i.v. (5 μg) or intracerebroventricular (50 ng) injection suppressed reflex milk ejection in intact, sham-lesioned and control-lesioned rats, but had no effect on either the pattern or magnitude of reflex milk ejection in rats with lesions of the subfornical organ. The subfornical organ, which is situated at the interface between the blood, brain and the cerebrospinal fluid appears to mediate, at least in part, the relaxin-induced inhibition of reflex milk ejection in the rat. J. Endocr. (1987) 115, 347–353

Polymorphisms of EDNRB, ATG, and ACE genes in salt-sensitive hypertensionThis article is one of a selection of papers published in the special issue (part 2 of 2) on Forefronts in Endothelin.

2008 ◽  
Vol 86 (8) ◽  
pp. 505-510 ◽  
Author(s):  
Jessica Caprioli ◽  
Caterina Mele ◽  
Chiara Mossali ◽  
Laura Gallizioli ◽  
Gilberta Giacchetti ◽  
...  
Keyword(s):  
Protective Role ◽  
Receptor Subtype ◽  
Genotype Distribution ◽  
High Salt Diet ◽  
Subtype B ◽  
Salt Depletion ◽  
Sensitivity Data ◽  
Pressure Changes ◽  
Salt Sensitive Hypertension

Almost 50% of hypertensive individuals manifest blood pressure changes in response to salt depletion or repletion and are termed “salt sensitive” (SS). Blunted activity of the endothelin (ET) system and the renin–angiotensin–aldosterone system (RAAS) have been reported as possible mechanisms contributing to salt sensitivity. Data are available that endothelin receptor subtype B (ETBR)-deficient rats develop salt-sensitive hypertension when fed a high-salt diet. Whether the ETBR gene (EDNRB) is involved in genetic predisposition to human salt-sensitive hypertension has not been studied so far. We screened EDNRB in 104 hypertensive patients (49 salt sensitive and 55 salt resistant) and 110 normotensive controls. No new sequence variation was found, but genotype distribution of the common polymorphism G1065A revealed that the AA + GA genotypes were significantly more frequent in salt-resistant than in salt-sensitive individuals (p = 0.007), suggesting a protective role for the A allele. We also screened angiotensinogen gene AGT M235T and angiotensin-converting enzyme insertion/deletion polymorphism ACE I/D and found an association between TT genotype and hypertension. A possible synergistic effect to salt-sensitive hypertension was found by combining EDNRB GG with ACE DD/ID genotypes. In conclusion, our data confirm the role of ET system and RAAS in salt-sensitive hypertension.

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