bluuebunny/crossref_metadata_2025_split huggingface dataset:
The sensitivity of the sodium pump to external sodium
Authors: Garrahan P. J. , Glynn I. M. 
Published: December 2014

1. When red cells are incubated in potassium‐free solutions, ouabain‐sensitive sodium efflux is nearly absent with 5 m
M‐Na externally, but increases as the external sodium concentration is reduced from 5 m
M to zero. This increase suggests that the transport mechanism is very sensitive to small amounts of sodium at the outside surface of the cell membrane. Further evidence for such sensitivity has been obtained from the effects of external sodium on the relation between potassium influx and external potassium concentration.2. With 5 m
M‐[K]o, potassium influx is rather insensitive to [Na]o but at low potassium concentrations even low levels of sodium inhibit.3. With 140 m
M‐[Na]o the potassium influx curve is S‐shaped below 1 m
M [K]o. At much lower sodium concentrations, the S‐shaped region and the value of [K]o for which potassium influx is half‐maximal are both shifted progressively towards zero. At 10 μ
M‐[Na]o, potassium influx is half maximal at 0·14 m
M‐[K]o and the curve is close to a rectangular hyperbola down to 22 μ
M‐[K]o; there seems to be a trace of inflexion at about 15 μ
M‐[K]o.4. When [Na]o is reduced from 5 m
M to zero, removal of the inhibitory effect of external sodium ions on sodium: potassium exchange could lead to an increase in sodium efflux into nominally potassium‐free solutions if these solutions did in fact contain traces of potassium. Such traces could arise by leakage from the cells, but, in a number of experiments, direct measurements showed that [K]o was too low to account in this way for all of the observed ouabain‐sensitive sodium efflux. A further reason for rejecting this explanation is that ouabain‐sensitive potassium loss into nominally (Na+K)‐free solutions was unaffected by adding 5 m
M‐Na. (A slight increase in ouabain‐resistant loss was observed.)5. The ouabain‐sensitive efflux of sodium into (Na+K)‐free solutions therefore seems to represent a mode of behaviour of the transport mechanism distinct both from the sodium: potassium exchange that occurs under physiological conditions and from the sodium: sodium exchange that occurs in K‐free, Na‐rich media.
The relation between secretion of urate and p‐aminohippurate in the rabbit kidney
Authors: Møller Jesper V. 
Published: December 2014

1. The renal excretion of urate in the rabbit was examined during infusion of other anions which are secreted by the kidney. A reduction of urate excretion occurred after administration of p‐aminohippurate (PAH) and Diodrast which was proportional to the secretory rate of these compounds. On the other hand, urate was a less efficient inhibitor of PAH secretion.2. Stop‐flow experiments showed that tubular secretion of urate at maximal values for secretion of PAH and Diodrast was almost completely suppressed.3. 2,4‐Dinitrophenol, fumarate, succinate, salicylate, and probenecid depressed the excretion of urate and PAH, but the tubular secretion of urate was apparently more depressed than that of PAH by these inhibitors.4. It is concluded that a common transport system for urate and PAH is involved in the tubular secretion of urate and PAH in the rabbit. However, the affinity of urate for the transport system appears to be smaller than that of PAH.
Local and reflex factors affecting the distribution of the peripheral blood flow during arterial hypoxia in the rabbit
Authors: Chalmers J. P. , Korner P. I. , White S. W. 
Published: December 2014

1. The effects of severe arterial hypoxia on the blood flow in the portal vein, and in kidney, muscle and skin beds have been determined in normal unanaesthetized rabbits, in animals without functioning autonomic effectors, and in rabbits with section of the carotid sinus and aortic nerves.2. The resting blood flows in the above regions were not significantly different in the three groups.3. The susceptibilities of the various beds to the local dilator effects of arterial hypoxia (assessed from the responses of animals without functioning autonomic effectors) were markedly different; vasodilatation was by far the greatest in the portal bed, followed in order by the renal, skin and muscle beds.4. Section of the carotid sinus and aortic nerves completely abolished reflex activity, and the pattern of peripheral blood flow changes was similar to that of animals without functioning autonomic effectors. The findings suggest that the arterial chemoreceptors are the primary afferent source of reflex control of the peripheral circulation in arterial hypoxia.5. In normal animals with intact reflexes there was sustained vasoconstriction throughout the treatment period in the portal and renal bed. The net vasomotor effects in muscle and limb skin were small owing to the operation of a number of factors, which opposed the effects of reflexly increased sympathetic nerve activity.
The responses of thalamic neurones to iontophoretically applied monoamines
Authors: Phillis J. W. , Tebēcis A. K. 
Published: December 2014

1. The effects of noradrenaline (NA), adrenaline, dopamine (DA) 5‐hydroxytryptamine (5‐HT) and a number of related drugs were tested on the extracellularly recorded responses of neurones in the feline thalamus. Substances were applied iontophoretically and tested on synaptically, antidromically and chemically evoked neuronal activity.2. NA, adrenaline, isoprenaline and 5‐HT had a variety of effects, depressing some cells, exciting others and not affecting the responses of a third group. DA depressed most of the cells tested; excitation was not observed with this compound.3. The magnitude of depressant actions and their duration varied considerably. The more sensitive cells responded to extremely small amounts of catecholamine or 5‐HT and recovery often took several minutes. Recovery after DA was always rapid. Neurones in the dorsal thalamus were generally more susceptible to depression than those in the ventro‐basal complex.4. Excitatory responses were most marked in the ventro‐basal complex of the thalamus. Desensitization occurred if NA or adrenaline was applied repeatedly and this tachyphylaxis lasted for several minutes. After desensitization to the excitatory effects, some of these cells were depressed by catecholamines. These findings suggest the presence of at least two types of membrane receptor.5. β‐adrenergic antagonists (alderlin,
D‐INPEA and MJ 1999) and α‐antagonists (phentolamine, dibenzyline and chlorpromazine) had pronounced depressant actions on some thalamic neurones. With the exceptions of
D‐INPEA and MJ 1999 they also excited cells that were excited by the catecholamines. Alderlin and phentolamine had both excitatory and inhibitory effects on some cells.6. The monoamine oxidase inhibitor, iproniazid, depressed neurones which were sensitive to NA depression. It did not appear to potentiate the effects of NA on most of the cells tested.7. Reticular formation stimulation depressed some neurones in the thalamus and excited others. The depressant effects of NA and reticular formation stimulation were reduced or abolished by an intravenous injection of picrotoxin (1 mg/kg).8. It is suggested that NA and 5‐HT may be inhibitory transmitters in the thalamus, released at the terminals of ascending pathways from the brain stem that have been defined by fluorescence microscopy. The excitatory actions of these compounds may also be related to a synaptic role.
Circulatory responses of supine subjects to the exposure of parts of the body below the xiphisternum to subatmospheric pressure
Authors: Ardill B. L. , Bannister R. G. , Fentem P. H. , Greenfield A. D. M. 
Published: December 2014

1. Observations are reported on the effects of exposure of parts of the body below the level of the xiphisternum of supine subjects to a pressure 70 mm Hg below atmospheric for 1 min.2. The stress on the circulation was greater than when parts below the iliac crests were similarly exposed. Heart rate increased by 15‐20 beats/min, there was a sustained fall in arterial blood pressure, and forearm blood flow fell profoundly and in some subjects was reduced to below 0·1 ml./100 ml. min.3. In arms that were sympathectomized, or had received an intraarterial infusion of an adrenergic blocking drug, the fall in forearm blood flow was much less and could be related to the fall in arterial pressure.4. When the suction was released there was a brief overshoot of arterial blood pressure and brief cardiac slowing. Forearm blood flow rose to reach a peak some 15 sec after the release.5. In the sympathectomized forearm on release of suction there was an immediate rise in blood flow which was proportionately much greater than the rise in arterial blood pressure.6. This rise was not due to circulating vasodilator substances or to the activity of cholinergic vasodilator nerves. The possibility that it was the result of a change in the tone of the resistance vessels occurring in response to the sudden change in transmural pressure is discussed.
Intracellular autogenetic and synergistic effects of muscular contraction on flexor motoneurones
Authors: Green D. G. , Kellerth J.-O. 
Published: December 2014

1. Intracellular records have been taken from cat motoneurones innervating flexor muscles of the hind limb. Contractions of the ankle flexors tibialis anterior and extensor digitorum longus were elicited by stimulation of the peripheral end of the cut L 7 ventral root and the reflex effects of these contractions were recorded in silent and repetitively firing motoneurones.2. Contraction usually produces a hyperpolarizing response inside flexor motoneurones. This hyperpolarization is tension‐sensitive in the sense that when, at constant muscle extension, the strength of the contraction is increased, the magnitude of the inhibitory response is augmented.3. Increasing the resting length of the muscles, while using a stimulus of constant strength to the ventral root, causes this inhibitory response to increase in some cells. More often, however, the hyperpolarization caused by contraction is gradually reduced in duration and/or amplitude as the muscles are extended.4. Even with the muscles slackened, so that they develop no tension at their ends, contraction usually produces prominent hyperpolarization of the motoneurones.5. By passing polarizing currents or injecting chloride ions through the intracellular micro‐electrode, the hyperpolarizing potentials produced by contraction of the slack and extended muscles are shown to be, at least in part, genuinely post‐synaptic inhibitory events.6. When the neurone is fired repetitively by injected current, the ‘silent period’ in contraction corresponds to the hyperpolarization of the post‐synaptic membrane.7. Monosynaptic testing of the flexor motoneurone pool has been used to confirm the essential features of the intracellularly recorded activity.8. Acutely spinalizing the animal increases the magnitude of the inhibitory responses caused by contraction.9. Recordings from dorsal root fibres show that Golgi tendon organs of the ankle flexors are very sensitive to contraction and are indeed often activated by the internal forces developed in a contracting slack muscle.10. A number of muscle spindles of the ankle flexors are activated by stimulation of the ventral root at a strength submaximal or just maximal for the α‐motor fibres, despite the simultaneous unloading effect of the contracting extrafusal fibres. This spindle activation, which occurs mainly during the phase of tension development in contraction, is favoured by an increased extension of the muscle. Attempts were made to establish whether it is due to α‐motor innervation of the receptors or to some mechanical interaction between the intra‐ and extrafusal muscle fibres.11. The possible central and peripheral causes of the changes in motoneurone excitability produced by flexor muscle contraction are discussed. It is suggested that tendon organs of flexor muscles strongly inhibit flexor motoneurones and that α‐motor innervation of muscle spindles is likely to play a more prominent role in flexors than in extensor muscles.
Transport of potassium by the colon of normal and sodium‐depleted rats
Authors: Edmonds C. J. 
Published: December 2014

1. Ascending and descending segments of colon of normal and Nadepleted rats were perfused with solutions of differing KCl concentration. Net K flux, electrical p.d. and, in some experiments, unidirectional K fluxes were measured.2. Variation of luminal K concentration over the range 0‐40 m
M did not affect p.d. or K efflux rate.3. K secretion rate fell about 30% when Na‐free choline chloride solution was perfused.4. Net flux was a linear function of the luminal K concentration, and fell as the latter increased. Na depletion increased K secretion rate and passive permeability of the mucosa to K. Adrenalectomy had the reverse effect. The luminal K concentration, associated with zero net K flux was much greater than expected if the colonic mucosa behaved passively with respect to K.5. Unidirectional fluxes determined when 5 m
M‐KCl was in the lumen showed that the ratio influx/efflux was much less than predicted by Ussing's flux ratio equation.6. It was concluded that K influx was due to simple diffusion and K efflux to diffusion and active transport, both processes being increased by Na depletion.
The experimental induction of hypophosphataemia in goats using anion exchange columns
Authors: Symonds H. W. , Treacher R. J. 
Published: December 2014

1. Inorganic phosphate was selectively removed from the circulating blood of five anaesthetized goats by means of columns of anion‐exchange resin. Concentrations of other ions were unaffected by the column.2. Rates of inorganic phosphate extraction in excess of 5 m‐moles/hr caused a fall in plasma inorganic phosphate of up to 50% in 30 min.3. In four of the goats the calculated inorganic phosphate mobilization rate rose sharply to a maximum between 5.8 and 12.7 m‐moles/hr and then fell progressively as more phosphate was removed.4. During the course of the experiments a fall in blood pressure occurred, accompanied by a rise in blood glucose. The reasons for this are discussed.
A Study of the Development of an Analytical Wall Function for LES
Authors: Amano R. S. , Hasegawa Takahiko , Shen Shaohua 
Published: December 2014

In order to invent a new near-wall treatment for turbulence in Computational Fluid Dynamics (CFD) simulation, an Analytical Wall Function (AWF) has been studied and shown that it is possible to work accurately with Reynolds Averaged Navier-Stokes (RANS) Simulation even for complicated geometry such as impinging jet flow or separation and reattachment flow. One of the most common wall functions is the Standard Wall Function (SWF) which assumes log-law inside the boundary layer. However, there is a problem that SWF has been used for industrial applications even though it is difficult to analyze the turbulence phenomenon in a complicated geometry accurately because log-law is not applicable in that geometry. On the other hand, since AWF derives the boundary condition on the wall by integrating analytically the boundary layer equation in wall adjacent cells, it can analyze the turbulence accurately even in complicated geometry. AWF has an advantage over SWF from this point of view.
In this study, AWF was improved and optimized for Large Eddy Simulation (LES) by changing the way of modeling of eddy viscosity inside the boundary layer for steady state simulation to that for unsteady state simulation. This is because RANS is a steady state simulation; on the other hand, LES is unsteady state simulation, which is one of the largest differences between them. The accuracy of the new AWF for LES (LES-AWF) was validated by both of experimental results and CFD simulation results. Both of the experiment and CFD simulation are conducted in the wind tunnel.
Numerical Investigation of the Flow Around a Generic Car Using Dynamic Mode Decomposition
Authors: Peichl Martin , Mack Steffen , Indinger Thomas , Decker Friedhelm 
Published: December 2014

The drag of a car is highly dependent on the topology of its complex wake system. Small changes in the shape of the car, that do not have a big effect when considered separately, can lead to significant changes in the total drag when the vortex systems of the changed part of the car body interact with the wake vortices. To understand these interferences, a method is necessary that decomposes the flow based on dynamic information. In this paper, the feasibility of using the Dynamic Mode Decomposition (DMD) to analyze the dynamic behavior of the wake flow of a car is investigated. The DMD is found to extract useful information from the flow when applied to three dimensional velocity vector fields.
The CFD simulations are validated by yet unpublished experimental results from experiments in two different wind tunnels.
Numerical Modeling of Vertical Axis Wind Turbines
Authors: Parra-Santos Teresa , Gallegos-Muñoz Armando , Rodriguez-Beneite Miguel A. , Uzarraga-Rodriguez Cristobal , Castro-Ruiz Francisco 
Published: December 2014

This paper aims to predict the performance of Vertical Axis Wind Turbine (VAWT), hence the modeling of kinetic energy extraction from wind and its conversion to mechanical energy at the rotor axis, is carried out. The H-type Darrieus turbine consists of three straight blades with shape of aerofoil attached to a rotating vertical shaft. The criterion on the selection of this kind of turbines, despite its reduced efficiency, is the easy manufacture in workshops.
A parametric study has been carried out to analyze the camber effect on the non dimensional curves of power coefficient so that the self starting features as well as the range of tip speed ratio of operation could be predicted.
Thermodynamic Effect on Cavitation in High Temperature Water
Authors: Yamaguchi Yuki , Iga Yuka 
Published: December 2014

Thermodynamic effect on cavitation appears in cryogenic fluids, refrigerant and high temperature water. The thermodynamic effect is considered to suppress the development of cavitation and improve the performance of hydraulic machinery. However, the actual appearance degree of thermodynamic effect depends on not only thermal property of each fluid but also each hydraulic machinery and its operating condition. So, the clarification of the influence of the flow field with unsteady cavitation on the degree of thermodynamic effect is necessary. In order to investigate thermodynamic effect, many experiments had been conducted with using cryogenic fluids or refrigerant as working fluids. However, there are some difficulties to visualize cryogenic fluids and the experimental results cannot be directly correlated to the condition without thermodynamic effect in same fluid.
In the present study, in order to conduct cavitation experiments with and without thermodynamic effect in same fluid, high temperature and high pressure cavitation tunnel had been constructed. The working fluid of this tunnel is water and the free-stream temperature can be varied from room temperature to 140 °C. In the present study, NACA 0015 hydrofoil had been chosen as a cavitator.
The extent of thermodynamic effect was estimated through the measurement of temperature in the cavity. The temperature was measured by a thermistor probe which has high accuracy. When the thermodynamic effect appears, temperature depression in the cavity is observed. The maximum temperature depression of cavity about 0.3 K had been measured in water of 80 °C.
Turbulent Kinetic Energy Budget and Dissipation in the Wake of 2D Obstacle: Analysis of the K-ε Closure Model
Authors: Gamel H. , Salizzoni P. , Soulhac L. , Méjean P. , Marro M. , Grosjean N. , Carissimo B. 
Published: December 2014

The prediction of the flow dynamics produced by the interaction between a sheared turbulent flow and a bluff body has important implications in the domain of the wind engineering and for what concerns the simulation of atmospheric dispersion of air-born pollutants.
In this study we present the results of the experimental investigation on the wake of a 2D obstacle, immersed in a neutrally stratified boundary layer flow. Measurements are performed by means of two different techniques, namely Laser Doppler Anemometry and Stereo-Particle Image Velocimetry. These allow us to map the spatial evolution of the velocity statistics up to their third order moments.
The study focuses in particular on the budget of the turbulent kinetic energy (t.k.e.) and the estimate of its mean dissipation rate. The experimental data-set is the basis for a detailed analysis of the reliability and the main limitations of a classical k-ϵ closure model. This has major implication for the numerical simulation of pollutant dispersion in the built environment.
LES of Turbulent Airflow Field and Microparticle Deposition in a Realistic Model of Human Upper Airways
Authors: Ghahramani Ebrahim , Abouali Omid , Emdad Homayoon , Ahmadi Goodarz 
Published: December 2014

The Large Eddy Simulation (LES) technique was used to study the turbulent airflow field in a realistic model of human upper airways. The geometric model includes nasal cavity, pharynx, larynx and trachea. The Lagrangian approach was used to calculate the trajectories and deposition of micro-particles for the breathing rate of 60 l/min. The results are compared with those obtained from the RANS model from an earlier study. For the latter model the effect of airflow turbulent velocity fluctuations on particle trajectories was modeled using a Continuum Random Walk (CRW) stochastic model.
A qualitative comparison of the results obtained by the LES method with the earlier RANS model reveals that the total depositions of micro-particles evaluated be these two methods are similar. The LES and RANS predictions for regional depositions, however, differ significantly.
Reynolds Number Dependence of Laminar Loss Coefficients for a Rectangular-Cross Section Square-Cornered Tee Junction
Authors: Ring Brock P. , Lin Yunhao , Henderson Andrew W. , Hossan Mohammad , Lemley Evan C. 
Published: December 2014

Energy losses in junctions are often found by using an assumed loss coefficient for the particular geometry. While this coefficient remains nearly constant under turbulent conditions, this is not true for laminar flow. The loss coefficient through a dividing junction tends to decrease as a function of Reynolds number converging to some value once fully turbulent flow occurs. Research has been done to catalog losses for various geometries under turbulent flow; yet, there has not been the same detailed research for the laminar conditions. This is mostly due to many applications at the macro scale where turbulent flow is prevalent. Flow in microchannels and nanochannels is mostly laminar. Applications at this small scale have created a demand for the study of these loss coefficients under the laminar flow conditions.
This paper focuses on simulations done of flow through a square-cornered tee-junction with a rectangular cross sectional area of 6 by 7 millimeters. The fluid consisted of a glycerin and water mixture that was 30 percent water and 70 percent glycerin by volume. Measurements were made of an actual mixture’s density and viscosity and these parameters were used in the simulations. The mixture was chosen to give sufficient pressure drop to measure in validation experiments. Using these simulations, a detailed account of the energy losses in the junction was observed as a function of Reynolds number. The Reynolds number range in this study was 1–100. Higher Reynolds numbers were simulated where signs of a transition to turbulence were observed.
The stagnation loss coefficient, which includes kinetic energy and pressure changes through the junction, was found to be inversely proportional to Reynolds number. Initial experimental verification has been performed, in which the experimental stagnation loss coefficient followed the same trend as the simulations. Additional experimental validation is underway.