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We report a generalized Geertsma solution with which we can calculate the surface deformation from a subsurface made of an arbitrary number of isotropic homogeneous layers and a thick reservoir at any depth. We validate the generalized Geertsma solution by solving simple numerical examples and comparing the results with a reference finite-element solution. Then, we apply the generalized Geertsma solution to more realistic subsurface models to study the effect of subsurface layering on surface deformation and the impact of acquisition-processing accuracy on inverted reservoir pressure. The modelling demonstrates the surface deformation (both magnitude and shape) is most influenced by the reservoir stiffness. Finally, the inversion exercise demonstrates that for the case of In Salah-inspired synthetic model, 3% noise resulting from data acquisition-processing error may introduce 15% deviation in the inverted pressure compared to the true reservoir pressure.

QC 20220322

QC 20220322

The aims were to study effects of iterative exposures to moderate elevations of local intravascular pressure on arterial/arteriolar stiffness and plasma levels of vasoactive substances. Pressures in the vasculature of an arm were increased by 150mmHg in healthy men (n = 11) before and after a 5-wk regimen, during which the vasculature in one arm was exposed to fifteen 40-min sessions of moderately increased transmural pressure (+65 to +105 mmHg). This vascular pressure training and the pressuredistension determinations were conducted by exposing the subjects' arm versus remaining part of the body to differential ambient pressure. During the pressure-distension determinations, venous samples were simultaneously obtained from pressurized and unpressurized vessels. Pressure training reduced arterial pressure distension by 40 ± 23% and pressure-induced flow by 33 ± 30% (P < 0.01), but only in the pressure-trained arm, suggesting local adaptive mechanisms. The distending pressure-diameter and distending pressure-flow curves, with training-induced increments in pressure thresholds and reductions in response gains, suggest that the increased precapillary stiffness was attributable to increased contractility and structural remodeling of the walls. Acute vascular pressure provocation induced local release of angiotensin-II (ANG II) and endothelin-1 (ET-1) (P < 0.05), suggesting that these vasoconstrictors limited the pressure distension. Pressure training increased basal levels of ET-1 and induced local pressure release of matrix metalloproteinase 7 (P < 0.05), suggesting involvement of these substances in vascular remodeling. The findings are compatible with the notion that local intravascular pressure load acts as a prime mover in the development of primary hypertension. QC 20220214

Purpose It has been reported that the cold-induced vasodilation (CIVD) response can be trained using either regular local cold stimulation or exercise training. The present study investigated whether repeated exposure to environmental stressors, known to improve aerobic performance (heat and/or hypoxia), could also provide benefit to the CIVD response. Methods Forty male participants undertook three 10-day acclimation protocols including daily exercise training: heat acclimation (HeA; daily exercise training at an ambient temperature, T-a = 35 degrees C), combined heat and hypoxic acclimation (HeA/HypA; daily exercise training at T-a = 35 degrees C, while confined to a simulated altitude of similar to 4000 m) and exercise training in normoxic thermoneutral conditions (NorEx; no environmental stressors). To observe potential effects of the local acclimation on the CIVD response, participants additionally immersed their hand in warm water (35 degrees C) daily during the HeA/HypA and NorEx. Before and after the acclimation protocols, participants completed hand immersions in cold water (8 degrees C) for 30 min, followed by 15-min recovery phases. The temperature was measured in each finger. Results Following the HeA protocol, the average temperature of all five fingers was higher during immersion (from 13.9 +/- 2.4 to 15.5 +/- 2.5 degrees C; p = 0.04) and recovery (from 22.2 +/- 4.0 to 25.9 +/- 4.9 degrees C; p = 0.02). The HeA/HypA and NorEx protocols did not enhance the CIVD response. Conclusion Whole-body heat acclimation increased the finger vasodilatory response during cold-water immersion, and enhanced the rewarming rate of the hand, thus potentially contributing to improved local cold tolerance. Daily hand immersion in warm water for 10 days during HeA/Hyp and NorEx, did not contribute to any changes in the CIVD response.