The effect of repeated cold exposure of the hand on the reactivity of digital vessels

1969 ◽  
Vol 47 (3) ◽  
pp. 261-265 ◽  
Author(s):  
Peter Gaskell ◽  
Kathleen L. Long
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Cold Exposure ◽  
Opening Pressure ◽  
Relative Flow Rate ◽  
Opposite Hand ◽  
Critical Opening ◽  
Before And After ◽  
Relative Change ◽  
Relative Flow

One hand of each of 10 subjects was immersed in stirred water at 4 °C for 1 h per day, 5 days per week, for 3 weeks, to produce local acclimatization to cold. The opposite hand was immersed at the same time in water at 32 °C. The reactivity of digital vessels in a finger of each hand was measured as the increase in the critical opening pressure of the vessels in response to an intravenous infusion of noradrenaline at 2 and 5 μg/min. The reactivity of digital vessels in the test hand was compared with that in the control hand both before and after the repeated cold exposure of the test hand to see whether the cold exposure altered the reactivity of vessels in the test hand relative to that in the control hand. No evidence of such a relative change was obtained. Resting blood flow at 21 and 32 °C in the test hand was compared with that in the control hand both before and after the repeated cold exposure. No change in the relative flow rate in the two hands was observed as a result of the cold exposure. Roentgen studies of the hands did not reveal any effect of the repeated cold exposure on the mineralization of the bones of the hands.

scholarly journals Increase fish protective efficiency constructions of meliorative water intake

2020 ◽  
pp. 69-73
Author(s):  
Svetlana Mikhailovna Dragunova ◽  
Yevgeniy Vladimirovich, Кuznetsov ◽  
Anna Yevgenievna Khadzhidi
Keyword(s):  
Physical Model ◽  
Water Intake ◽  
Flow Rate ◽  
Juvenile Fish ◽  
Protective Efficiency ◽  
Irrigation Systems ◽  
Relative Flow Rate ◽  
Reclamation System ◽  
Relative Flow ◽  
Fish Protection

The article solves the problem of increasing the level of protection of juvenile fish to a standard indicator by the modernization of individual elements of fish protection of ameliorative water intake of irrigation systems. The design of an integrated fish-protecting structure with a logging boom adapted to hydrology and the rhythm of migration of juvenile fish from irrigation sources has been proposed. The results of studies on a physical model, taking into account the costs of the reclamation system, show an increase in the efficiency of the combined fish protection structure with a harbor for reclamation water intakes in the range of 78,5–84,0 %, depending on the relative flow rate on the shelf of the sanctuary.

Critical opening pressure and reactivity of tail vessels in conscious hypertensive rats

1976 ◽  
Vol 54 (3) ◽  
pp. 314-321
Author(s):  
A. C. Darke ◽  
P. G. Nair ◽  
P. Gaskell
Keyword(s):  
Blood Pressure ◽  
Renovascular Hypertension ◽  
Vascular Reactivity ◽  
Experimental Hypertension ◽  
Hypertensive Rats ◽  
Opening Pressure ◽  
Critical Opening ◽  
Resistance Vessels ◽  
Before And After ◽  
Desoxycorticosterone Acetate

The possible role of increased vascular reactivity in the mechanism of experimental hypertension was studied by measurements of the critical opening pressure (COP) of tail vessels in conscious rats. In hypertension induced by administration of desoxycorticosterone acetate (DOCA) and replacement of the drinking water by 1% NaCl solution (DOCA–NaCl hypertension), and in one-kidney Goldblatt renovascular hypertension, the raised level of blood pressure was associated with an increased COP of the tail vessels when measured both before and after ganglionic blockade. In rats treated with either DOCA alone or 1% NaCl alone there was no significant increase in systolic blood pressure (SBP) or COP relative to the corresponding controls. In all four experimental series intravenous infusion of angiotensin or norepinephrine in conscious ganglion-blocked rats produced dose-dependent increases in SBP and COP. In DOCA–NaCl hypertensive rats but not in renovascular hypertensives, nor in rats treated with DOCA alone or 1% NaCl alone, the increase in COP for a given increment in dose of angiotensin or norepinephrine was significantly greater than in the control rats. It is concluded that in DOCA–NaCl hypertension there is a true increase in the reactivity of the smooth muscle of the resistance vessels to angiotensin and norepinephrine. In renovascular hypertension this is not the case and other factors must therefore be involved in causing the increased blood pressure and COP.

scholarly journals Investigation of Low-Temperature Lean Combustion Characteristics in Power Plants with External Heating of Components

2021 ◽  
Vol 2(50) ◽  
Author(s):  
Nikolay Bachev ◽  
◽  
Alena Shilova ◽  
Oleg Matyunin ◽  
Oksana Betinskaya ◽  
...  
Keyword(s):  
Low Temperature ◽  
Combustion Chamber ◽  
Flow Rate ◽  
Turbulent Combustion ◽  
Power Plants ◽  
Lean Combustion ◽  
Relative Flow Rate ◽  
External Heating ◽  
Low Emission ◽  
Relative Flow

An integral part of any open-type gas turbine plant is a low-emission combustion chamber, which is usually two-zone and cooled. One of the ways to reduce emission of harmful substanc-es is organizing low-emission low-temperature lean combustion with external heating of compo-nents. This paper investigates the effect of external heating of air and fuel gas on expansion of the lower combustion limit and stable flame position in a single-zone uncooled combustion chamber of a microgas turbine power plant. Stable position of the flame front in combustion chambers of this type mainly depends on the ratio between the average flow rate of the combus-tible-air mixture and the rate of turbulent combustion. This ratio depends on thermal, gas-dynamic, thermochemical and geometric factors. The purpose of this work is to substantiate the possibility of using the relative flow rate as a generalized characteristic. This goal was achieved in processing a large amount of published experimental data and numerical modeling of low-temperature combustion of lean mixtures. The most significant research result is determination of the range of relative flow rate (gk = 0.3…3.5·10-4 kg⁄s∙N), at which it is possible to ensure sta-ble flame position in a single-zone combustion chamber. Significance of the obtained results lies in the fact that using the relative flow rate makes it possible to quickly determine and analyze the geometric and gas-dynamic parameters and characteristics of turbulent combustion in com-bustion chambers of micro-gas turbine power plants.

Abstract W P76: Parent Artery Curvature May Help Determine the Effectiveness of Flow Diverter Treatment

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Brando Dimapasoc ◽  
Aichi Chien
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Simulation Analysis ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Parent Artery ◽  
Flow Volume ◽  
Aneurysm Neck ◽  
Flow Reduction ◽  
Before And After

Introduction: Flow diverters (FDs) aim to treat intracranial aneurysms by altering intra-aneurysmal hemodynamics. Reports have suggested aneurysm and parent artery shape may affect flow reduction in FD-treatment. The purpose of this study is to gain insight into the way in which aneurysm shape and parent artery curvature influence the ability of FDs to redirect flow. Hypothesis: Aneurysm dome size and parent artery curvature affect FD-induced flow reduction within an aneurysm. Methods: FD models constructed based on the Pipeline Embolization Device with 35% area coverage, 30 um strand diameter, and 4 mm nominal diameter were implemented for hemodynamic simulation analysis. The flow reduction effects were tested using aneurysm models featuring different dome sizes and parent artery curvatures. Aneurysm blood flow was analyzed before and after FD stenting in regions of the aneurysm neck, body, and dome. Results: We found that aneurysms with higher parent artery curvature had increased systole flow volume entering aneurysms before and after stenting, regardless of aneurysm size, with pre-FD volume flow rates for curvatures of 20 and 30 degrees, respectively, 1.54 and 2.40 times those for 10 degree curvature. Furthermore, FD reduced flow less in aneurysms with higher curvature. For parent artery curvatures of 10, 20, and 30 degrees, overall reductions of flow volume entering the aneurysm were 91.1±0.56%, 88.2±1.2%, and 85.5±0.28%, respectively. 97.2% of models had more flow reduction at the aneurysm dome than neck. Figure 1 shows representative, post-FD flow in 10 and 30 degree parent arteries, with a greater volume flow rate in (b) depicted by denser streamlines. Aneurysm dome size was not found to have a significant effect on volume flow rate. Conclusions: We found that artery curvature may have a large influence on FD flow reduction, indicating that FD may be less effective at reducing blood flow entering aneurysms located within higher curvature arteries.

scholarly journals Biological treatment of drippers clogged by the use of treated domestic wastewater

2016 ◽  
Vol 20 (7) ◽  
pp. 595-599
Author(s):  
Danniely O. Costa ◽  
Rafael O. Batista ◽  
Hudson S. M. Vale ◽  
Amanda B. de Sousa ◽  
Solange A. G. Dombroski ◽  
...  
Keyword(s):  
Flow Rate ◽  
Biological Treatment ◽  
Statistical Difference ◽  
Domestic Wastewater ◽  
Rate Reduction ◽  
Relative Flow Rate ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Different Doses ◽  
Relative Flow

ABSTRACT This study aimed to recover the flow rate of clogged drippers with different doses and permanence times of the product MaxBio. The experiment was conducted in a completely randomized design in split-split-plot scheme, where the plots corresponded to product doses (80, 160, 240 and 320 mg L-1), subplots to the applied treatments (T1 - without biological treatment, T2 - 1st application of the product, and T3 - 2nd application of the product) and in sub-subplots the types of emitters (Plastro Hydrodrip Super, Netafim Tiran and Netafim PCJ-CNJ), with three replicates. The four irrigation units operated with treated domestic wastewater for 400 h in order to clog the emitters. After applying the product MaxBio, the flow rate of the drippers and the relative flow rate reduction were determined to express the unclogging levels. There was significant effect of T2 and T3 on the recovery of the flow rate of the drippers, while for the reduction of relative flow rate, the doses of the product did not show statistical difference regarding the types of drippers.

The Blood Supply of the Tendon with a Paratenon

HAND ◽  
1983 ◽  
Vol os-15 (1) ◽  
pp. 9-14 ◽  
Author(s):  
M. Naito ◽  
K. Ogata
Keyword(s):  
Blood Flow ◽  
Soft Tissue ◽  
Achilles Tendon ◽  
Blood Supply ◽  
Flow Rate ◽  
Vascular System ◽  
Blood Flow Rate ◽  
Soft Tissue Dissection ◽  
Tissue Dissection ◽  
Before And After

The blood supply to the central third of the Achilles tendon was studied in adult rabbits using the hydrogen washout technique before and after soft tissue dissection including paratenon. The soft tissue dissection caused a decrease of the blood flow rate in the Achilles tendon by approximately 35 per cent. These results may indicate that the central third of the tendon with a paratenon receives its blood supply from the extrinsic vascular system by approximately 35 per cent and from the intrinsic vascular system by approximately 65 per cent.

High Blood flow Rates with Adjustment of Needle Diameter do not Increase Hemolysis during Hemodialysis Treatment

2007 ◽  
Vol 8 (4) ◽  
pp. 252-257 ◽  
Author(s):  
F. Techert ◽  
S. Techert ◽  
L. Woo ◽  
W. Beck ◽  
H. Lebsanft ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Venous Pressure ◽  
Blood Flow Rate ◽  
Needle Size ◽  
Flow Rates ◽  
Blood Damage ◽  
Before And After ◽  
Needle Diameter ◽  
Hb Concentration

Background Higher blood flow in dialysis therapy is often avoided due to concerns about shear-induced blood damage despite the lack of reliable data. Objective This study investigated the influence of higher blood flow rates on plasma free hemoglobin (Hb) concentration after hemodialysis (HD) treatment. Methods Thirty-two chronic HD patients were treated once with a blood flow rate of 250 mL/min using a 17G needle, and once with a blood flow rate of 500 mL/min using a 14G needle. Arterial and venous pressure and blood pressure (BP) were recorded before and after treatment. Blood samples were taken before and after treatment for analysis of plasma free Hb, pH, HCO3, base excess, hematocrit value, urea, sodium, potassium and calcium. Results HD treatment at blood flow rates of 500 mL/min did not increase plasma free Hb compared to treatments at blood flow rates of 250 mL/min. Frequency of intradialytic BP drops was not different either. By adaptation of the needle size, negative arterial pressure could be kept at a similar level. Urea reduction rates were significantly higher during treatments with higher blood flow rates. Conclusion Higher blood flow rates can be applied without an increased hemolysis risk provided that needle sizes are adapted accordingly.

scholarly journals EFFECT OF OXIDANT RELATIVE FLOW RATE ON OBTAINING RAW MATERIAL FOR PULVERIZED COAL PRODUCTION FROM HIGH-SULFURIC LOW GRADE COAL

2017 ◽  
Vol 11 (2) ◽  
pp. 236-241 ◽  
Author(s):  
Mariіa Shved ◽  
◽  
Serhiy Pyshyev ◽  
Yuriy Prysiazhnyi ◽  
◽  
...  
Keyword(s):  
Flow Rate ◽  
Pulverized Coal ◽  
Raw Material ◽  
Low Grade ◽  
Coal Production ◽  
Relative Flow Rate ◽  
Relative Flow

Investigation of Hydrodynamic Focusing in a Microfluidic Coulter Counter Device

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Muheng Zhang ◽  
Yongsheng Lian ◽  
Cindy Harnett ◽  
Ellen Brehob
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Coulter Counter ◽  
Hydrodynamic Focusing ◽  
Relative Flow Rate ◽  
Advection Diffusion Equation ◽  
Sample Stream ◽  
Voltage Signal ◽  
The Impact ◽  
Relative Flow

The Coulter technique enables rapid analysis of particles or cells suspended in a fluid stream. In this technique, the cells are suspended in an electrically conductive solution, which is hydrodynamically focused by nonconducting sheath flows. The cells produce a characteristic voltage signal when they interrupt an electrical path. The population and size of the cells can be obtained through analyzing the voltage signal. In a microfluidic Coulter counter device, the hydrodynamic focusing technique is used to position the conducting sample stream and the cells and also to separate close cells to generate distinct signals for each cell and avoid signal jam. The performance of hydrodynamic focusing depends on the relative flow ratio between the sample stream and sheath stream. We use a numerical approach to study the hydrodynamic focusing in a microfluidic Coulter counter device. In this approach, the flow field is described by solving the incompressible Navier-Stokes equations. The sample stream concentration is modeled by an advection-diffusion equation. The motion of the cells is governed by the Newton-Euler equations of motion. Particle motion through the flow field is handled using an overlapping grid technique. A numerical model for studying a microfluidic Coulter counter has been validated. Using the model, the impact of relative flow rate on the performance of hydrodynamic focusing was studied. Our numerical results show that the position of the sample stream can be controlled by adjusting the relative flow rate. Our simulations also show that particles can be focused into the stream and initially close particles can be separated by the hydrodynamic focusing. From our study, we conclude that hydrodynamic focusing provides an effective way to control the position of the sample stream and cells and it also can be used to separate cells to avoid signal jam.

Effect of potassium on renal vascular resistance and urine flow rate

1959 ◽  
Vol 197 (2) ◽  
pp. 305-308 ◽  
Author(s):  
Jerry Scott ◽  
Dean Emanuel ◽  
Francis Haddy
Keyword(s):  
Blood Flow ◽  
Potassium Chloride ◽  
Vascular Resistance ◽  
Flow Rate ◽  
Blocking Agent ◽  
Urine Flow ◽  
Renal Vascular Resistance ◽  
Urine Flow Rate ◽  
Before And After ◽  
Renal Vascular

The effect of potassium chloride upon renal vascular resistance and urine flow rate was studied in anesthetized laparotomized dogs. Potassium chloride was infused directly into the renal artery with the rate of blood flow to the kidney held constant and with flow rate not controlled. Resistance progressively decreased when serum potassium level in the kidney was elevated by infusing 0.11–0.69 mEq K+/min. It progressively increased when the infusion rate exceeded 0.69 mEq/min. This relationship was unaltered by the adrenergic blocking agent phentolamine. Urine flow rate increased both before and after denervation of the kidney when potassium was infused at the rate of 0.6 mEq/min. This increase was not apparent when the rate of blood flow was held constant. These findings indicate that a local potassium excess in amounts which might occur naturally leads to dilatation of renal vessels and increase of urine flow rate. The latter probably is related to the former.

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