Showing papers on "Water flow published in 1968"

Relationship of Water Potential to Growth of Leaves

Abstract: A thermocouple psychrometer that measures water potentials of intact leaves was used to study the water potentials at which leaves grow Water potentials and water uptake during recovery from water deficits were measured simultaneously with leaves of sunflower (Helianthus annuus L), tomato (Lycopersicon esculentum Mill), papaya (Carica papaya L), and Abutilon striatum Dickson Recovery occurred in 2 phases The first was associated with elimination of water deficits; the second with cell enlargement The second phase was characterized by a steady rate of water uptake and a relatively constant leaf water potential Enlargement was 70% irreversible and could be inhibited by puromycin and actinomycin D During this time, leaves growing with their petioles in contact with pure water remained at a water potential of -15 to -25 bars regardless of the length of the experiment It was not possible to obtain growing leaf tissue with a water potential of zero It was concluded that leaves are not in equilibrium with the potential of the water which is absorbed during growth The nonequilibrium is brought about by a resistance to water flow which requires a potential difference of 15 to 25 bars in order to supply water at the rate necessary for maximum growthLeaf growth occurred in sunflower only when leaf water potentials were above -35 bars Sunflower leaves therefore require a minimum turgor for enlargement, in this instance equivalent to a turgor of about 65 bars The high water potentials required for growth favored rapid leaf growth at night and reduced growth during the day

The mechanisms of sodium absorption in the human small intestine

Abstract: The present studies were designed to characterize sodium transport in the jejunum and ileum of humans with respect to the effects of water flow, sodium concentration, addition of glucose and galactose, and variations in aniomic composition of luminal fluid. In the ileum, sodium absorption occurred against very steep electrochemical gradients (110 mEq/liter, 5-15 mv), was unaffected by the rate or direction of water flow, and was not stimulated by addition of glucose, galactose, or bicarbonate. These findings led to the conclusion that there is an efficiently active sodium transport across a membrane that is relatively impermeable to sodium. In contrast, jejunal sodium (chloride) absorption can take place against only the modest concentration gradient of 13 mEq/liter, was dramatically influenced by water movement, and was stimulated by addition of glucose, galactose, and bicarbonate. The stimulatory effect of glucose and galactose was evident even when net water movement was inhibited to zero by mannitol. These observations led to the conclusion that a small fraction of jejunal sodium absorption was mediated by active transport coupled either to active absorption of bicarbonate or active secretion of hydrogen ions. The major part of sodium absorption, i.e. sodium chloride absorption, appeared to be mediated by a process of bulk flow of solution along osmotic pressure gradients. The stimulatory effect of glucose and galactose, even at zero water flow, was explained by a model in which the active transport of monosaccharide generates a local osmotic force for the absorption of solution (NaCl and water) from the jejunal lumen, which, in the presence of mannitol, is counterbalanced by a reverse flow of pure solvent (H(2)O) through a parallel set of channels which are impermeable to sodium. Support for the model was obtained by the demonstration that glucose and bicarbonate stimulated the absorption of the nonactively transported solute urea even when net water flow was maintained at zero by addition of mannitol to luminal contents.

Functional consequences of ultrastructural geometry in "backwards" fluid-transporting epithelia.

Abstract: Many fluid-transporting epithelia possess dead-end, long, and narrow channels opening in the direction to which fluid is being transported (basal infoldings, lateral intercellular spaces, etc.). These channels have been thought to possess geometrical significance as standing-gradient flow systems, in which active solute transport into the channel makes the channel contents hypertonic and permits water-to-solute coupling. However, some secretory epithelia (choroid plexus, Malpighian tubule, rectal gland, etc.) have "backwards" channels opening in the direction from which fluid is being transported. It is shown that these backwards channels can function as standing-gradient flow systems in which solute transport out of the channel makes the channel contents hypotonic and results in coupled water flow into the channel mouth. The dependence of the transported osmolarity (isotonic or hypertonic) on channel radius, length, and other parameters is calculated for backwards channels for values of these parameters in the physiological range. In addition to backwards channels' being hypotonic rather than hypertonic, they are predicted to differ from "forwards" channels in that some restrictions are imposed by the problem of solute exhaustion, and in the presence of a sweeping-in effect on other solutes which limits the solutes that may be transported.

Catastrophic Drift of Insects in a Woodland Stream

Abstract: The effect of early fall rains on the downstream drift or displacement of insects was studied for two seasons by collecting the entire streamflow at one point through a drift net. Drift rate increased within 24 hr after the start of each rainy period, with the increase approximately proportional to the increase in stream flow. Freshets due to less than 1 in. (2.5 cm) of rain caused a fourfold increase in numbers and fivefold to eightfold increase in biomass. Major components of the drift were Ephemeroptera, Plecoptera, Diptera and terrestrial insects. Plecoptera and Ephemeroptera retained the day—night periodicity of behavioral drift during freshets, but drift of Chironomidae (Diptera) was attributed to catastrophic and constant drift. Mean weight per individual of several taxa was greater at night than day, in freshet than nonfreshet periods, and in drift compared with benthos samples. Though catastrophic drift due to fall freshets displaced large numbers of individuals, the standing crop of the benthos increased during the fall because of hatching. The drift may be beneficial in dispersing aggregations of young larvae. Removal of allochthonous food by increased water flow could be more detrimental to benthos populations than the direct mortality caused by catastrophic drift.

Theoretical Analysis of Two-Dimensional, Transient Flow of Water in Unsaturated and Partly Unsaturated Soils1

Abstract: The Darcian flow-equation for two-dimensional, transient transfer of water in rectangular, unsaturated or partly unsaturated soil slabs was solved numerically with the aid of alternating-directions, implicit difference methods. Two alternative processes were considered: predominantly horizontal infiltration and ditch-drainage. The results obtained for the horizontal infiltration process indicate that it involves upward flow-components which are due, primarily, to a gravity-induced variation in hydraulic conductivity along the inflow face. These components may materially affect the course of infiltration, especially during its earlier stages. The drainage case results demonstrate that transient water flow within the unsaturated zone and the outflow from the seepage zone may significantly affect the progress of water-table descent and the total outflow rates. Additional

Effects of Vasopressin, Theophylline and Cyclic Adenosine Monophosphate on Short-circuit Current across Isolated Rabbit Ileal Mucosa

Abstract: VASOPRESSIN causes rapid, equal increases in short-circuit current (Isc) and rate of transport of sodium when added to the serosal surface of frog skin or toad bladder1,2. Several investigators have presented convincing evidence that this alteration in the active transport of sodium is primarily, if not entirely, a consequence of increased passive permeability of the mucosal surface to sodium, as well as to other small hydrophilic solutes3–5. Adenosine-3′,5′-monophosphate (cyclic AMP) and theophylline have been shown to mimic the effects of vasopressin on Isc and osmotic water flow across toad bladder6. It has been suggested that cyclic AMP is the more direct mediator of the permeability change and that vasopressin and theophylline exert their effects by increasing the concentration of cyclic AMP in the epithelial cells7.

Design of Optimal Water Distribution Networks

Abstract: A linear programming solution is presented for the problem of selecting optimal pipe diameters, and head at the source for a water distribution network. The water discharge and pressure requirements at all points in the system are assumed to be known and remain constant, and the configuration of the network connecting the points to the single source is regarded as given. Solution of the model using a digital computer yields the combination of diameters and lengths of pipes for all sections of the network and the required head at the source to minimize the total cost of the system.

The Effect of Ouabain on the Rabbit Corneal Endothelium

Abstract: With the method of in vitro incubation of the isolated rabbit cornea with the modified KEI medium, the effects of ouabain applied to the endothelial surface have been investigated. The change in corneal hydration with varying concentrations of ouabain was determined; one-half maximum rate of corneal swelling was found at an ouabain concentration of 3 x 10~ 7 moles per liter. Endothelial permeability in corneas exposed to ouabain was evaluated by assessing permeability to water flow and to radioactive nonelectrolytes. No significant change in these permeability coefficients was found in the corneas which were swelling under the influence of ouabain as compared to normal corneas.

A Method of Estimating the Relative Volumes of Water Flowing Over the Different Gills of a Freshwater Fish

Abstract: 1. A technique is described which uses marker parasites to estimate the relative volumes of water flowing over the different gills of a freshwater fish. 2. It was found that in brown trout from Windermere most of the respiratory current flows over the second and third pairs of gills, less flows over the first pair on each side and least of all across the most posterior pairs of gill. Similarly, the median pair of gill slits carries more of the respiratory current than any of the other slits whereas first and fifth pairs of gill slits together carry only about one-sixth of the total water flow. 3. Hatchery-bred brown trout showed a slight but significant difference in pattern of water movement over their gills following vigorous exercise. Possible reasons for this are discussed.

Cyclic Variations in Plant Properties under Constant Environmental Conditions

Abstract: Cyclic fluctuations in stomatal aperture, transpiration rate and leaf water potential under constant environmental conditions have been investigated in intact plants of cotton, pepper, and sunflower. Stomatal aperture and transpiration rate were least when leaf water potential was high and were greatest when leaf water potential was low. Lowest leaf water potential values lagged behind the occurrence of highest transpiration rates, and high overall resistance to water flow occurred in cycling plants. Both of these are considered essential for the occurrence of persistent cyclic behaviour. Hydropassive opening of stomates as the leaves wilted facilitated cycling in cotton and pepper, but not in sunflower, where hydropassive opening did not occur. The roots were identified as the site of the major resistance to water flow in the plant and further experiments directly showed the importance of this root resistance in initiating cycling by causing water stress in the leaves as the stomates opened. Root resistance varied diurnally, becoming increasingly important at night. Root resistance naturally rose to high levels in cotton. High levels were induced in pepper or sunflower by having the roots in deionized water for several days or by anoxia. Quantitative measurements of overall plant resistance were made from leaf water potential and transpiration rate data. The results are discussed and it suggested that plant resistance may indirectly be of importance in the movement of water from the plant to the air.

Water movements and their role in rocky shore ecology

Abstract: Water movement is considered in terms of water flow and wave crash, although differentation is not always possible. Ocean currents and residual drift mainly effect geographical distributio...

Nonlinear Flow Through Granular Media

Abstract: Relative roles of steady and unsteady fluid motion in causing deviation from the linear Darcy resistance law are described. Air velocities and turbulence intensities were measured within the pores of a gravel bed by hot-wire anemometers. Results indicate that although the linear resistance relation ceases to be valid at a Reynolds number of about 2, velocity fluctuations do not begin until the Reynolds number is about 100, and turbulence is not fully established until it is at least 800. Studies of water flow through a coarse sand bed showed that convergence of the macro-streamlines significantly reduced the resistance at Reynolds numbers over about 10, the proportionate reduction increasing with flow. The observations are interpreted in terms of flow through coiled pipes or round immersed objects, and four regimes of flow through granular media are proposed.

Defined Velocity Gradient Model Flocculator

Abstract: The importance of flocculation in the removal of up to micron sized mineral and biological particles led to the study of a defined velocity gradient flocculator. The design desiderata are outlined and the theoretical basis given. The coaxial cylinder, Couette device developed is described and its hydraulic testing discussed. Mention is made of floc flow patterns observed in flocculation tests with quartette particles and alum.

Oxygen consumption and gill water flow in the dogfish Scyliorhinus canicula L.

Abstract: 1. Determinations of the standard oxygen consumption of the dogfish Scyliorhinus canicula , by several different methods, gave values in the range of 20-55 c.c./kg./hr. at 12°C. 2. When the rate of water flow over the resting fish is increased, there is an increase in oxygen consumption, but no marked change in respiratory frequency at the flow rates studied. An increase of respiratory frequency took place when the P O 2 of the inspired water was reduced. 3. The ventilation volume of the dogfish was measured by collecting the water in chambers after it had passed over the gills. The resting ventilation volume was about 120 c.c./min./kg. at 12° C. 4. The relationship between the flow across the gills and the imposed hydrostatic pressure gradient (Δ p ) showed a linear relationship. The fish was unable to continue pumping water across the gills against adverse gradients in excess of 0.7 cm. H 2 O. 5. When the flow across the gills was relatively low, utilization of oxygen of at least 70% was observed, but with increasing flow rates this fell to between 40 and 50%.

The depth of rain water on road surfaces

Abstract: THE DEPTH OF WATER RESULTING FROM STEADY RAINFALL ON PLANE ROAD SURFACES OF BRUSHED CONCRETE AND ROLLED ASPHALT WITH CHIPPINGS WAS STUDIED. THE SURFACES, WHICH ARE CURRENTLY USED ON MOTORWAYS IN THE UNITED KINGDOM, WERE STUDIED WITH THE AID OF A LARGE TILTING PLATFORM WHICH COULD BE SPRAYED WITH WATER TO SIMULATE RAINFALL OF VARIOUS INTENSITIES. THE DISTRIBUTION OF WATER ON THE SURFACES OF ROLLED ASPHALT WITH CHIPPINGS AND ON THE BRUSHED CONCRETE WAS SIMILAR, INDICATING THAT AS FAR AS THE HYDRAULICS OF RAIN WATER FLOW IS CONCERNED, THE SURFACES CAN BE CONSIDERED TO HAVE SIMILAR ROUGHNESSES. THIS IS PROBABLY DUE TO THE RAINDROP IMPACT BEING THE SIGNIFICANT FACTOR AFFECTING THE SHALLOW WATER FLOW. THE WATER DEPTH (D CM) IS RELATED TO THE DRAINAGE LENGTH (L M), RAINFALL INTENSITY (I CM/H) AND SLOPE (1/N) BY THE FORMULA D = 0.015 (L X I)TO THE 1/2 POWER TIMES N TO THE 1/5 POWER. INCREASING THE SLOPE OF A ROAD PAVEMENT FROM 1 IN 60 TO 1 IN 30 DECREASES THE DEPTH OF WATER ON THE ROAD BY ONLY 11 PER CENT AND IT IS CONCLUDED THAT THE MAJOR BENEFIT OF A STEEP CROSSFALL IS THE REDUCED VOLUME OF WATER WHICH CAN POND IN DEFORMATIONS OF THE PAVEMENT. /RRL/A/

Stochastic Analysis of Daily River Flow

Abstract: Optimum water resources design may be achieved using data generation techniques based on models statistically derived from historical records of a hydrologic variable. However, certain statistical techniques of time series analysis are restricted to series possessing the time-invariance property which hydrologic data might not possess. The analysis of river flow records in the light of this limitation is presented. To obtain a mathematical representation of daily streamflow, a trend-free model made up of an oscillatory component and an autoregressive process is postulated to apply to the records of five rivers. The oscillatory component is detected and isolated using spectral and fourier analyses, and Markov schemes are fitted to the standardized residual series. The adequacy of the models fitted is examined through a comparison of the theoretical variance with the computed variance resulting from the application of the model. The importance of the underlying series, which is the sequence generated in Monte Carlo techniques, is discussed.

Der Einfluß von Hydrochlorothiazid und anderen sulfonamidierten Diuretica auf die 3′,5′-AMP-Phosphodiesterase-Aktivität in der Rattenniere

Abstract: Vasopressin has been reported to accelerate the conversion of adenosine triphosphate to cyclic 3′,5′-AMP by stimulating the activity of the adenyl cyclase. According to the view of Orloff and Handler cyclic 3′,5′-AMP is responsible for the augmentation of osmotic water flow. The cyclic nucleotide ist degraded by the enzyme 3′,5′-AMP phosphodiesterase (PDE) to 5′-AMP. Inhibition of this enzyme by theophylline results in an increase in the concentration of 3′,5′-AMP and a concomittant increase in osmotic water flow, as shown in the urinary bladder of the toad (Bufo marinus). The experiments presented in this paper derived from a previous observation that furosemide and hydrochlorothiazide inhibit PDE. Both diuretics have been shown to reduce renal PDE activity when injected i.v. to rats in a dose of 25 mg/kg. Following injection of furosemide PDE activity has been found reduced only in the cortex, the effect of hydrochlorothiazide has been shown to be restricted to the inner medulla. Studies on the subcellular distribution of renal PDE revealed two fractions, one third of total activity bound to large particles, probably cell membranes, two third soluble in the hyaloplasm. The two fractions of the enzyme differ in their k m-value for 3′,5′-AMP. Subcellular distribution and k m-values of PDE in the liver have been found to be identical with those in the kidney. Hydrochlorothiazide has been shown to affect both fractions of renal PDE. Because of the restriction of the action of furosemide to the renal cortex no attempt was made to differentiate the effect of the compound with respect to its subcellular localization. Accumulation of 3′,5′-AMP caused by an impaired degradation of the nucleotide in this region could lead to an increase in the permeability of the distal convoluted tubules to water. As the difference in the osmotic pressure between distal tubular fluid and the surrounding interstitial fluid is relatively small, the increase in water permeability can only result in a small increase in tubular water reabsorption. In view of hydrochlorothiazide reducing PDE activity in the inner medulla and the high difference in the osmotic pressure between the fluid in the collecting tubules and the interstitial fluid it is suggested that a hydrochlorothiazide induced increase in water permeability results in a high increase in water rea-absorption, especially in diabetes insipidus where there is a low osmolarity of the tubular fluid in the collecting duct with an unimpaired cortico-papillary osmotic gradient. This corresponds to the paradoxical antidiuretic effect of diuretics in the treatment of diabetes insipidus centralis and renalis, especially after diuretic induced sodium depletion and reduction of the osmolarity of tubular fluid resulting in an increased osmotic difference between fluids within collecting ducts and interstitium.

Electric pressing iron

Abstract: An electric pressing iron having a smooth, substantially non-porous, corrosion resistant member secured within a recess at the bottom of a valve seat. This member, surrounding the orifice portion of the water control valve between the iron water tank and steam generating chamber, will reduce corrosion and the attachment of mineral deposits at this critical section of the steam iron, thereby extending the life of the iron as well as maintaining consistent control of water flow.

Stability of towed, totally submerged flexible cylinders

Abstract: A general theory is presented to account for the small, free, lateral motions of a flexible, slender, cylindrical body with tapered ends, totally submerged in liquid and towed at steady speed U. For particular shapes of the ends and length of tow-rope, it is shown that the body may be subject to oscillatory and non-oscillatory instabilities for U > 0; at small U, these instabilities correspond to those of a rigid body. At higher U, the system generally regains stability in the above modes, but may be subject to higher-mode, flexural oscillatory instabilities. The critical conditions of stability are calculated extensively and the effect on stability of a number of dimensionless parameters is discussed. It is shown that optimum stability is achieved with a streamlined nose, a blunt tail and a short tow-rope.Some experiments are described which were designed to test the theory. Rubber cylinders of neutral buoyancy were held in vertical water flow by a nylon ‘tow-rope’. Provided the tail was streamlined and the tow-rope not too short, ‘criss-crossing’, non-flexural oscillations developed at very low flow. Increasing the flow, these oscillations ceased and the cylinder buckled like a column; subsequently higher-mode flexural oscillations developed. However, for a sufficiently blunt tail and short tow-rope, the system was completely stable.The experimental observations are generally in qualitative agreement with theory. Quantitative comparison of the various instability thresholds and stable zones between experiment and theory, based on estimated values of some of the theoretical dimensionless parameters, is also fairly good.

A System for Measuring Conductivity, Acidity, and Rate of Water Flow in a Forest Soil

Abstract: An integrated system for collecting, recording, and analyzing data describing the behavior of water flowing through a forest soil has been developed. The collecting and recording components are located on a lower terrace of the City of Seattle Cedar River watershed in western Washington. This system includes tension lysimeters installed such that the overlying soil and rooting systems are undisturbed. The lysimeters are constructed from a fused aluminum oxide disk 11 inches (28 cm) in diameter. The suction to each lysimeter is maintained through a single controlled vacuum source. Solutions collected during periods of flow are passed through flow cells measuring conductivity, acidity, and rate of water flow. The sensitivity of the soil moisture flowmeter is in excess of 0.002 cm/hr. The electrical output from the flow cells is coupled to a data-logging facility and printed as perforations in paper tape. Computer analysis converts these data to tabular and graphic form. Examples demonstrating the functioning of the system during periods of flow are presented.

Theory and Performance of Water Jet Pump

Abstract: The theoretical maximum ideal pumping efficiency of a water jet pump is 50% at a flow ratio of unity. Pump performance can be predicted theoretically. With a pump designed with theoretically obtained optimum dimensions, a maximum efficiency of 39.8% was achieved. Efficiencies on the order of 42% could be obtained by selecting proper materials to reduce friction losses to a minimum. If a jet pump with fixed nozzle is constructed for maximum efficiency, the area ratio should be between 0.33 to 0.543; for adjustable nozzle pumps, the area ratio should be about 0.205, and the pump should be operated at a nozzle distance of one to two nozzle diameters.

Critical reynolds number for sinusoidal flow of water in rigid tubes

Abstract: Experimental friction factor for pulsatile water flow, obtaining empirically pressure drop and flow rate data

Location of Bulinus (Physopsis) globosus by miracidia of Schistosoma haematobium.

Abstract: Young Bulinus (Physopsis) globosus snails were exposed to miracidia of Schistosoma haematobium under various conditions of mutual dispersion to investigate host location mechanisms. There is little variation in infectivity of miracidia taken from different human hosts on different days. Exposure of one snail to one miracidium in cylindrical vessels with diameters ranging from 2.3 to 29.0 cm filled to 0.5 cm depth resulted in infection of about 42% of snails; this percentage did not increase if three snails were used in each exposure. With the snails confined under small perspex cages, the percentage infected by single miracidia rose significantly. It is suggested that this was the result of a chemotaxis, and experiments using a simple Y-maze demonstrated an initial response some distance from the snail. In a long trough miracidia were found to range over 294 cm in still water; in water flowing at 15 cm/sec 10 miracidia per snail produced no infections. At 7.5 cm/sec 6.7% of snails became infected. The introduction of a weir to cause turbulence increased infection. It is suggested that miracidia of S. haematobium are unable to infect snails in moderately fast-flowing water unless turbulence occurs near the snails. The success of the free swimming miracidium in finding its host is an important feature in the bionomics of schistosomes. Selective pressures must have evolved the most efficient means of finding and infecting the appropriate snail. It is therefore reasonable to presume that in the miracidium specific mechanisms exist adapted to the behavior and physiology of the appropriate intermediate host. Faust (1924) pointed out a distinct difference between the behavior of miracidia of Schistosoma japonicum (Mollendorf) and those of S. haematobium (Weinland) derived from the northern African snail Bulinus truncatus (Audouin), and suggested that this was an adaptation to the habits of the different intermediate host snails. Wright (1959a) in discussing host location by trematode miracidia has presented arguments suggesting the presence of a chemical attraction between the host snail Biomphalaria (= Australorbis) glabrata (Say) and the miracidia of S. mansoni Sambon. Recently, Maclnnis (1965) showed that miracidia of S. mansoni react positively to chemostimulation in the form of either the appropriate host snails, or extracts of these snails, or to small agar pyramids impregnated with chemicals such as butyric, glutamic, or sialic acids. He reports Gottschalk (1960) as stating that sialic acids are known to be components of mucopolysaccharides, substances which may be present in the mucus of snails Received for publication 16 February 1968. (Wright, 1959b); similarly, Etges and Decker (1963), using a four-arm maze, concluded that S. mansoni miracidia were attracted to B. glabrata. However, Chernin and Dunavan (1962), investigating infection of B. glabrata by miracidia of S. mansoni in various sized vessels, concluded that attraction between the miracidium and the snail had not been demonstrated unequivocally. Host location in running water has been investigated by Webbe (1966) using a trough and the miracidia of S. mansoni with Biomphalaria sudanica tanganyicensis (Smith). He concluded that water flow may enhance the scanning capacity of miracidia because he obtained high infection rates in caged snails exposed to miracidia in water flowing at velocities of 0.5 to 3.5 ft/sec (15 to 105 cm/sec). The work reported here concerns the ability of S. haematobium miracidia to infect Bulinus (Physopsis) globosus (Morelet) under different conditions of mutual dispersion in still and flowing water. Many of Chernin and Dunavan's experiments have been repeated and acknowledgment for these is duly tendered. MATERIALS AND METHODS Snails were laboratory-bred B. globosus. They were exposed when the shell height was between 3.5 to 5.0 mm; i.e., between 4 and 8 weeks old. Parent colonies and young snails were maintained at room temperature in the laboratory. Unless otherwise stated, all exposures of snails to miracidia were carried out in the dark and in constant temperature cabinets regulated to 22 ? 0.5 C. In this way extraneous stimuli were elim-

Effects of Water Temperature on Bed-Load Movement

Abstract: LABORATORY INVESTIGATIONS HAVE INDICATED THAT THE EFFECTS OF WATER TEMPERATURE ON THE MOVEMENT OF SEDIMENT AND ON FLOW IN ALLUVIAL STREAMS CAN BE APPRECIABLE. SOME VARIATIONS NOTED IN FLOW CONDITIONS IN THE FIELD CAN BE ATTRIBUTED TO THE EFFECTS OF WATER TEMPERATURE. INFORMATION AVAILABLE ON THE SUBJECT HAS BEEN CONFUSING, OR TOO GENERAL TO PERMIT THE DEVELOPMENT OF DEFINITE RELATIONS. AN INVESTIGATION UNDERTAKEN TO DETERMINE THE EFFECTS OF CHANGES IN WATER TEMPERATURE ON SEDIMENT TRANSPORT, STREAM-BED FORMS, AND BED ROUGHNESS FOR VARIOUS TYPES OF MATERIAL IS DESCRIBED. AN INTERIM REPORT ON PROGRESS OF THIS INVESTIGATION AND PROCEDURES USED INCLUDES SOME OF THE PRELIMINARY INDICATIONS AND CONCLUSIONS. /ASCE/

Electromyography of the respiratory muscles and gill water flow in the dragonet.

Abstract: 1. An account is given of the main skeletal elements and muscles involved in the respiratory movements of the dragonet, Callionymus lyra . 2. Using electromyographic techniques it has been shown that the muscles chiefly involved in rapid ejection of water out of the opercular slit are the adductor mandibulae, protractor hyoideus, and hyohyoideus. During the expansion phase of the cycle, which is about six times the duration of the contraction phase, the levator hyomandibulae and sternohyoideus are active, though in some cases the latter only comes in at higher levels of pumping. 3. Changes in volume flow across the gills have been produced by either ( a ) altering the hydrostatic pressure gradient (Δ p ) across the system, or ( b ) altering the oxygen or carbon dioxide content of the water inspired by the fish. With ( a ), the volume flow decreases linearly at a rate of about 30 ml./min./cm. H 2 O static pressure head until an inflexion is reached in the curve at which rate of flow decreases and is normally when Δ p is zero. That the relative increase in flow rate with negative Δ p 9s is due to the activity of the fish pumping against the adverse pressure gradient has been confirmed by electromyogram recordings during such experiments. With ( b ), it was possible to demonstrate a clear relationship between stroke volume and the level of electrical activity as measured by the height of the integrated electromyogram. The integrated EMG increases more than linearly with increasing stroke volume during P O 2 changes, but this relationship seems to be more nearly linear during changes in CO 2 concentration. 4. The respiratory frequency is scarcely affected by changes in flow produced by altering the hydrostatic pressure gradient, but following a decrease in P O 2 or an increase in CO 2 there is a significant fall in frequency which accompanies the increased electromyogram. The time course of these changes during recovery from a decrease in P O 2 or an increase in P CO CO2 suggests that the gas tensions of the inspired water are detected by receptors on the gills and thus influence the electromyogram activity, but the frequency change observed is due to a change in the blood affecting receptors in the brain.