scholarly journals Predicting the Curvature of the Cosmos, and Point of Volume Contraction in a Big Bounce Scenario

2021 ◽  
Vol 11 (02) ◽  
pp. 265-278
Author(s):  
Christopher Pilot
Keyword(s):  
Volume Contraction ◽  
Big Bounce

Volume-regulated arginine vasopressin release in conscious dogs. Evidence for dopaminergic or opioid modulation?

1988 ◽  
Vol 119 (1) ◽  
pp. 106-112 ◽  
Author(s):  
L.J. Hellebrekers ◽  
E. Lagerweij ◽  
H W. de Vries ◽  
Tj. B. van Wimersma Greidanus
Keyword(s):  
Body Weight ◽  
Conscious Dogs ◽  
Control Group ◽  
Vasopressin Release ◽  
Volume Contraction ◽  
Endogenous Dopamine ◽  
Respective Control Group ◽  
Basal Release ◽  
Basal Plasma ◽  
Baseline Levels

Abstract. The possibility of a dopaminergic and/or opioid modulation of the volume-regulated release of AVP was investigated in conscious dogs. Either bromocriptine, 10 μg/kg body weight po, or naloxone, 0.1 mg/kg body weight iv, was administered prior to induction of nonhypotensive hypovolemia. Volume contraction of 15 ml/kg body weight was induced gradually, over a period of 30 min. Basal plasma AVP levels in the bromocriptine group were not significantly different from control group values. Bromocriptine administration significantly augmented AVP release following volume contraction. Mean arterial pressure in the bromocriptine group decreased to a slightly, but significantly, lower level than that in the control group. Mean arterial pressures, however, did not adequately explain the magnitude of the AVP response in the bromocriptine group. In the naloxone group, neither baseline levels, nor AVP values following volume contraction, differed significantly from respective control group values. In conclusion, the results suggest the possibility of a stimulatory role for endogenous dopamine in the volume-regulated, but not the basal, release of AVP in conscious dogs.

scholarly journals How to quantify isotropic negative thermal expansion: magnitude, range, or both?

2019 ◽  
Vol 6 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Chloe S. Coates ◽  
Andrew L. Goodwin
Keyword(s):  
Thermal Expansion ◽  
Material Property ◽  
Negative Thermal Expansion ◽  
Volume Contraction ◽  
Magnitude Range

Negative thermal expansion (NTE) is the counterintuitive material property of volume contraction on heating. We compare different systems with contrasting mechanisms for isotropic NTE using the metric of NTE capacity.

Importance of chloride for the correction of chronic metabolic alkalosis in the rat

1987 ◽  
Vol 253 (5) ◽  
pp. F1031-F1039 ◽  
Author(s):  
B. M. Wall ◽  
G. V. Byrum ◽  
J. H. Galla ◽  
R. G. Luke
Keyword(s):  
Plasma Volume ◽  
Metabolic Alkalosis ◽  
Choline Chloride ◽  
Plasma Renin ◽  
Sodium Balance ◽  
Sprague Dawley ◽  
Volume Contraction ◽  
Chloride Depletion ◽  
Sprague Dawley Rats ◽  
Sodium And Potassium

To determine whether chloride repletion without sodium could correct chronic chloride depletion metabolic alkalosis (CDA) in Sprague-Dawley rats without volume expansion and without increasing glomerular filtration rate (GFR), CDA was generated by peritoneal dialysis (PD) against 0.15 M NaHCO3 and maintained for 7-10 days by a chloride-restricted diet supplemented with sodium and potassium salts. Control animals were dialyzed against Ringer bicarbonate. The maintenance period of chronic CDA, compared with control, was characterized by hypokalemic metabolic alkalosis (serum TCO2 31.9 +/- 0.6 vs. 23.1 +/- 0.5 meq/l, P less than 0.05), volume contraction (plasma volume 3.76 +/- 0.08 vs. 4.19 +/- 0.22 ml/100 g body wt, P less than 0.05), decreased GFR (838 +/- 84 vs. 1045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), increased plasma renin activity (PRA) (63 +/- 13 vs. 12 +/- 3 ng.ml-1.h-1, P less than 0.05), but unchanged plasma aldosterone concentrations (PAC) (4.1 +/- 1.0 vs. 3.4 +/- 1.6 ng/dl, P = NS). Complete correction of chronic CDA was accomplished by 24 h of ingestion of choline chloride drink, and despite negative sodium balance, neutral potassium balance, continued bicarbonate ingestion, and persistent volume contraction (plasma volume 3.76 +/- 0.08 vs. 3.73 +/- 0.12 ml/100 g body wt pre- and postcorrection, P = NS), GFR remained decreased (659 +/- 87 vs. 1,045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), PRA decreased (63 +/- 13 vs. 33 +/- 5 ng.ml-1.h-1, P less than 0.05), but PAC did not change (4.1 +/- 1.0 vs. 6.1 +/- 1.6 ng/dl, P = NS) after correction of CDA.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals How to Quantify Isotropic Negative Thermal Expansion: Magnitude, Range or Both?

2018 ◽  
Author(s):  
Chloe Coates ◽  
Andrew Goodwin
Keyword(s):  
Thermal Expansion ◽  
Material Property ◽  
Negative Thermal Expansion ◽  
Microscopic Mechanism ◽  
Volume Contraction ◽  
Magnitude Range ◽  
Simple Question

<div>Negative thermal expansion (NTE) is the useful and counterintuitive material property of volume contraction on heating. Isotropic NTE is the rarest and most useful type, and is known to occur in a variety of different classes of materials. In this mini-review we ask the simple question of how best to compare NTE behaviour amongst these different systems? We summarise the two main mechanisms for isotropic NTE, and illustrate how these favour alternatively NTE magnitude</div><div>and NTE range. We argue in favour of a combined metric of NTE capacity, which balances both effects and allows unbiased identification of the most remarkable NTE materials, irrespective of the underlying microscopic mechanism at play. By organising known NTE materials according to these various metrics, we find intuitive trends in behaviour that help identify key materials for specific NTE applications.</div>

scholarly journals Primordial gravitational waves in a quantum model of big bounce

2018 ◽  
Vol 2018 (05) ◽  
pp. 057-057 ◽  
Author(s):  
Hervé Bergeron ◽  
Jean Pierre Gazeau ◽  
Przemysław Małkiewicz
Keyword(s):  
Gravitational Waves ◽  
Quantum Model ◽  
Primordial Gravitational Waves ◽  
Big Bounce

scholarly journals CYCLIC SHEAR-INDUCED VOLUME CONTRACTION CHARACTERISTICS AND ITS ASSESSMENT CHART OF ROCK DEBRIS UNDER EARTHQUAKES

2014 ◽  
Vol 70 (2) ◽  
pp. I_924-I_929
Author(s):  
Shinji SASSA ◽  
Yusuke GOTOH ◽  
Hiroyuki YAMAZAKI ◽  
Hidenori TAKAHASHI ◽  
Eiji KOHAMA
Keyword(s):  
Cyclic Shear ◽  
Volume Contraction

scholarly journals Big bounce with finite-time singularity: The F(R) gravity description

2017 ◽  
Vol 26 (08) ◽  
pp. 1750085 ◽  
Author(s):  
S. D. Odintsov ◽  
V. K. Oikonomou
Keyword(s):  
Big Bang ◽  
Einstein Frame ◽  
Jordan Frame ◽  
Cosmological Perturbations ◽  
Scale Invariant ◽  
Type Iv ◽  
Big Rip ◽  
Cosmological Scenario ◽  
The Big Bang ◽  
Big Bounce

An alternative to the Big Bang cosmologies is obtained by the Big Bounce cosmologies. In this paper, we study a bounce cosmology with a Type IV singularity occurring at the bouncing point in the context of [Formula: see text] modified gravity. We investigate the evolution of the Hubble radius and we examine the issue of primordial cosmological perturbations in detail. As we demonstrate, for the singular bounce, the primordial perturbations originating from the cosmological era near the bounce do not produce a scale-invariant spectrum and also the short wavelength modes after these exit the horizon, do not freeze, but grow linearly with time. After presenting the cosmological perturbations study, we discuss the viability of the singular bounce model, and our results indicate that the singular bounce must be combined with another cosmological scenario, or should be modified appropriately, in order that it leads to a viable cosmology. The study of the slow-roll parameters leads to the same result indicating that the singular bounce theory is unstable at the singularity point for certain values of the parameters. We also conformally transform the Jordan frame singular bounce, and as we demonstrate, the Einstein frame metric leads to a Big Rip singularity. Therefore, the Type IV singularity in the Jordan frame becomes a Big Rip singularity in the Einstein frame. Finally, we briefly study a generalized singular cosmological model, which contains two Type IV singularities, with quite appealing features.

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