bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visibility of aperiodic patterns compared with that of sinusoidal gratings
Authors: Campbell F. W. , Carpenter R. H. S. , Levinson J. Z. 
Published: December 2014

1. Using experimental curves relating the threshold contrast of sinusoidal grating patterns to their spatial frequency, the expected threshold contrast curves for three aperiodic patterns, viz. a single half‐cycle sinusoid bar, a single full‐cycle sinusoid bar, and the boundary between an extended sinusoidal grating and a 50% grey surround, are calculated. In this calculation the assumption is made that the system is linear near the threshold.2. Experiments are described in which the actual threshold contrast curves are determined for these aperiodic patterns by three observers. The patterns were generated on the face of an oscilloscope and could be varied in size and contrast.3. These experimental curves agree well with the predictions in the high frequency region (i.e. above about 10 c/deg), but below this various complicating factors restrict the validity of the calculations.4. Thus there is no reason to suppose that a linear theory cannot be used to predict visibility of aperiodic patterns near threshold.
The effects of length and stimulus rate on tension in the isometric cat soleus muscle
Authors: Rack P. M. H. , Westbury D. R. 
Published: December 2014

1. By subdividing ventral roots and supplying stimulating pulses to different groups of motor units in rotation, smooth contractions of soleus could be obtained with low rates of stimulation.2. Isometric tension was recorded with different rates of stimulation, and at different muscle lengths.3. Longitudinal histological sections were cut from muscles fixed at different lengths, and sarcomeres were measured. Mean sarcomere lengths in soleus could then be related to the angle at the ankle.4. At high rates of stimulation the maximum active tension was obtained at a length corresponding to an angle of about 60° at the ankle, and a mean sarcomere length of about 2·8 μ. The isometric tension fell only slightly on shortening the muscle to a length equivalent to 100°, and a mean sarcomere length about 2·3 μ. Further shortening caused a marked fall in tension.5. There was a reciprocal relationship between stimulus rate and muscle length; when the muscle was long low rates of stimulation gave near maximal tension, whereas at short lengths the maximum tension was reached only when the stimulus rate was very high. It is suggested that stimulating pulses activate the contractile machinery of the muscle more effectively at long than at short muscle lengths.6. When at low rates of stimulation pulses were distributed among the motor units in rotation to give a smooth contraction, the tension rose higher than during the unfused tetanus that accompanied synchronous stimulation of the same motor units at the same rate. It is suggested that in an unfused tetanus internal movement of the muscle reduces the tension below that developed in a truly isometric state.7. The rate of rise of tension in an isometric tetanus varied with both muscle length and rate of stimulation. At each stimulus rate there was a range of lengths in which the isometric tension developed slowly, this was the same length range in which, at that stimulus rate, the length tension curve was steep.
Structure and some contractile properties of fast and slow muscles of the chicken
Authors: Page Sally G. 
Published: December 2014

1. A comparative study has been made of the structure of the posterior and anterior latissimus dorsi muscles (
P.L.D. and
A.L.D.) of the chicken. Some of the contractile properties of these muscles, particularly of the
A.L.D. muscle, have also been examined.2. In confirmation of earlier work, it is found that structural differences between these two muscles mainly reside in the organization of the T‐system and the sarcoplasmic reticulum.3. In the
P.L.D. muscle the T‐system and sarcoplasmic reticulum are tubular networks of regular pattern, with frequent regions of contact between them in the form of the familiar triads. As described earlier, two series of triads are present in each sarcomere, near the level of the A—I boundary.4. The presence in the
A.L.D. muscle of both T‐system and sarcoplasmic reticulum has been established here by the combined use of electron microscopic and histochemical techniques. The appearance of these structures is considerably less regular in this than in the
P.L.D. muscle, and the area of contact between them relatively small: in terms of contact area per sarcomere, about 15% or less of that in the
P.L.D. muscle. Regions of contact are mainly in the form of dyads, but a few triads are also present.5. Contractures of the
A.L.D. muscle in high K fluids have been recorded and their modification due to variation of the external concentration of Ca, K and Mg examined. The K contracture consists of two phases: an initial transient and a later maintained phase. The response of these phases to variation in the external medium is markedly different.6. Application of Ca‐free fluids causes contracture tension of the late phase to subside within a few minutes whilst that of the initial phase declines completely only after several hours. High Mg concentrations depress the later but not the early phase of contracture.7. Tentative interpretations of both the morphological and physiological differences described have been proposed.
The rate of osmotic influx of water by flexible and inflexible erythrocytes
Authors: Sirs John A. 
Published: December 2014

1. The rate of osmotic influx of water into flexible and hardened erythrocytes has been studied using a stopped‐flow rapid‐reaction method, and diluting the cells 1:20 in hypotonic media.2. Neither the initial rate of swelling nor the time to the onset of haemolysis were changed after making the erythrocytes inflexible by adding formaldehyde or by heating at 48° C for 30 min.3. From a plot of the initial rate of uptake with hypotonicity, the permeability coefficient k can be calculated as 0·098 μ3/μ2. sec atm (± 10%) at 20·5° C.4. The value of k calculated from the time to the onset of haemolysis is 0·28 μ3/μ2 sec atm. This suggests individual cells may differ over a wide range of permeability.5. The results are consistent with the pores being at fixed sites in the membrane and unaffected by flexing of the cell.
The break‐down of [131I]γ‐globulin in the digestive tract of the new‐born pig
Authors: Hardy R. N. 
Published: December 2014

1. The intestinal absorption of [131I]porcine and bovine serum γ‐globulin after oral administration has been investigated in conscious pigs less than 20 hr old. Absorption was measured by the concentration of 131I in venous blood during the 6 hr after feeding and also by the distribution of 131I between homogenates of the alimentary tract and the rest of the animal at the end of the experiment.2. The concentration of 131I in the blood was always low after feeding [131I]γ‐globulin, although a large proportion of the isotope fed was found to have left the alimentary tract. This indicated that much of the [131I]‐γ‐globulin had been hydrolysed into fragments of low mol.wt. which were not retained in the plasma. There were no significant differences between results obtained with homologous and heterologous γ‐globulin.3. Examination by gel‐filtration confirmed that, after feeding [131I]‐serum γ‐globulin, much of the 131I in the plasma was associated with material of mol.wt. less than 12,400 and demonstrated that the break‐down of bovine γ‐globulin was comparable with that of homologous γ‐globulin.4. Comparison of the absorption of [131I]serum γ‐globulin from colostrum with that from a chloride solution with a similar Na+ and K+ concentration showed that, although the blood concentration remained low, colostrum reduced the hydrolysis of the labelled protein.5. This effect of colostrum could be simulated by the addition to the chloride solution of either the synthetic trypsin inhibitor Trasylol or a higher concentration of unlabelled protein.6. Gel‐filtration of samples of the contents of the stomach, duodenum and terminal ileum after feeding [131I]serum γ‐globulin showed that proteolysis occurred at all these sites.
Binocular depth discrimination and the nasotemporal division
Authors: Blakemore C. 
Published: December 2014

1. If classical partial decussation exactly segregates the projections of right and left hemi‐retinae on to the two optic tracts, the images of an object in central vision, nearer or further than the fixation point, should project to separate hemispheres. This would prevent the encoding of retinal disparity by binocularly driven neurones of the visual cortex.2. It is proposed that there is a central vertical strip of retina in each eye which is represented in both hemispheres. The angular width of this strip should be exactly one half the actual range of horizontal disparities of binocular receptive fields near the central vertical meridian.3. By recording from single neurones in the area 17/18 region in both hemispheres of a cat, it was found that there is such a strip of bilateral projection. The centres of receptive fields for units from the two hemispheres overlap in the middle of the visual field by about 1·5° and the
S.D. of the distribution is about 0·5°.4. The horizontal disparities of the centres of binocular receptive fields were measured for samples of units representing different parts of the visual field. The range of horizontal disparity for fields near the area centralis is about 2·3°, the
S.D. of the distribution about 0·9°. The proposed relationship between bilateral projection and disparity coding is thus confirmed.5. The origin of the bilateral projection is a matter of speculation, but in the cat some of it is almost certainly due to imprecision in the nature of the nasotemporal division of optic nerve fibres at the optic chiasma. A case can be made, however, that the overlap is partly due to connexions through the corpus callosum between the two occipital lobes.6. Evidence for the importance of the callosal pathway in man is drawn from the effects on stereopsis of section of the chiasma and the callosum.
Adaptation of canine pancreatic enzymes to diet composition
Authors: Behrman Harold R. , Kare Morley R. 
Published: December 2014

1. Lipase, protease and amylase activity in canine pancreatic juice were determined during the feeding of basal, high fat, high protein and high carbohydrate diets for 3‐week periods.2. The level of lipase in pancreatic juice was significantly augmented by increasing the dietary intakes of fat (P < 0·05) and carbohydrate (P < 0·05) but was not affected by increasing the protein intake.3. Protease activity was highly augmented by increasing the intake of protein (P < 0·01), was less strongly augmented by increasing carbohydrate (P < 0·10), but was not affected by the level of dietary fat ingested.4. Enzyme activities in canine pancreatic juice were modified by the nature of the diet on which the animals were maintained and the response for a given enzyme may be influenced by more than one dietary constituent.
The effect of the renin—angiotensin system on mucosal water and sodium transfer in everted sacs of rat jejunum
Authors: Crocker Ann D. , Munday Kenneth A. 
Published: December 2014

1. Mucosal water and sodium transfer were measured in everted sacs of rat jejunum.2. Rats maintained on a high sodium diet did not show consistently reduced mucosal water transfer and aldosterone also failed to stimulate transfer unless the control untreated values were low.3. Adrenalectomy produced little reduction in mucosal water transfer and aldosterone was without effect on water transfer in sacs from adrenalectomized rats.4. Vasopressin had no effect on mucosal transfer.5. Levels of water transfer were not reduced after hypophysectomy nor did aldosterone injection increase transfer.6. Mucosal water transfer in sacs from adrenalectomized—nephrectomized rats was low and was significantly increased by aldosterone injection or by injection of crude kidney extract.7. A significant increased mucosal water and sodium transfer was observed when sacs from adrenalectomized—nephrectomized rats were incubated with angiotensin at a concentration of 10−10g/ml.8. It is suggested that the renin—angiotensin system may be involved in the maintenance of sodium homoeostasis by a direct action on sodium transporting mechanisms.
Species and tissue variation in extraneuronal and neuronal accumulation of noradrenaline
Authors: Gillespie J. S. , Muir T. C. 
Published: December 2014

1. The ability of arterial and non‐arterial smooth muscle in five tissues (vas deferens, heart, bladder, colon, spleen) in four species (mouse, rabbit, rat, guinea‐pig) to accumulate and retain noradrenaline (NA) was measured in thin tissue slices exposed to NA for 30 min, then washed in cold saline solution for 30 min. NA accumulation was assessed histochemically by measuring the fluorescence brightness of the tissue with the Leitz MPV microphotometer. In addition, similar measurements were made on smooth muscle in the cat spleen, on cardiac muscle and on the terminal adrenergic nerves.2. In general, arterial smooth muscle had a greater capacity to accumulate and retain NA than non‐arterial smooth muscle, but there was a great species and organ variability. The ability to accumulate and retain NA was best developed in the mouse, followed by the rabbit, rat and guinea‐pig in that order. Among organs the artery to the vas and the coronary arteries showed the greatest retention. Among non‐arterial smooth muscle the mouse vas and the rabbit colon were notable.3. Cardiac muscle accumulates NA during exposure to the amine but, unlike smooth muscle, cannot retain it when washed with NA‐free solution.4. Terminal adrenergic nerves in different tissues show some variability in fluorescence intensity, and this is increased after exposure to NA. This may indicate a variable capacity of these cells to accumulate and retain NA.
Place and modality analysis in nucleus of posterior commissure
Authors: Bowsher David , Petit Denise 
Published: December 2014

1. Single units (157) responsive to somatic stimulation in the nucleus of the posterior commissure were examined in the cat under chloralose anaesthesia. 87·3% responded to stimulation of all four limbs, 2·4% to three limbs, 8·7% to two limbs and 2% to one limb.2. 44·7% of units could be activated by phasic hair movement; 52·4% responded additionally to auditory stimuli and 34·6% to visual stimuli, although there are marked differences in degree of heterosensory convergence between hair‐sensitive units and others.3. Analysis by spike numbers and latencies show marked preference for contralateral limbs.4. Results are compared with those obtained under identical experimental conditions from units of the gigantocellular bulbar reticular formation, and show that anatomically discrete areas of the reticular formation are capable of differential analysis of afferent input.
The roles of striated and smooth muscle in the movement of the cat's nictitating membrane
Authors: Paton W. D. M. , Thompson J. W. 
Published: December 2014

1. When the movement of the nictitating membrane is recorded in the usual way, pulled out under load in cat, dog, or rabbit, end‐plate‐depolarizing drugs such as succinylcholine, decamethonium, nicotine, and 2268F, cause a retraction.2. This movement is due to activation of orbital striated muscle, as evidenced by the resistance of the movement to ganglion block or excision of the superior cervical ganglion and to administration of phentolamine or atropine, and by its great sensitivity to dimethyltubocurarine.3. End‐plate‐depolarizing drugs produce contractions of the superior and inferior oblique and of the recti muscles strong enough to account for the movements of the nictitating membrane, provided the known fascial connexions of the orbit allow transmission of a fraction of the extraocular muscle movement to the membrane.4. In post mortem specimens with the front of the orbit undisturbed, retraction of the central end of any of the ocular muscles produces movement of the nictitating membrane; the movement was greatest with the superior oblique and medial rectus. In vivo, detaching the superior oblique from its insertion into the globe sometimes abolished or reduced the response to end‐plate‐depolarizing drugs.5. With the membrane unloaded and retracted into the medial canthus, in the lightly anaesthetized or unanaesthetized dog or cat, these drugs cause a protrusion of the membrane, which can be sufficient to cover the cornea. This response also resists ganglion‐block and is highly sensitive to dimethyltubocurarine.6. It is suggested that in the normal conscious animal the nictitating membrane is held retracted by a relatively small amount of sympathetic activity, and that its protrusion is an active mechanism under voluntary control mediated by the striated muscles of the orbit.7. The importance of these mechanisms in the interpretation of experiments in which the nictitating membrane is used are discussed.
The relation between body size and maximum and minimum metabolic rates in the new‐born pig
Authors: Mount L. E. , Stephens D. B. 
Published: December 2014

1. Measurements of rates of oxygen consumption were made on a total of sixty‐two Large White pigs aged between 1 hr and 6 days, with a range of body weight from 0·75 to 2·40 kg.2. The maximum rate was determined from the continuous estimation of oxygen consumption as the environmental temperature fell past the point at which the maximum occurred.3. The minimum rate was determined both as the environmental temperature rose through the zone of thermal neutrality, and from measurements at thermal neutrality.4. In animals aged 1‐6 days the mean maximum rate was 49·0 ml. O2/kg.min, and the mean minimum was 15·3 ml. O2/kg.min. Both rates were proportional to body weight and not to surface area.5. Pigs less than 1 day old exhibited lower maximum and minimum rates than the older pigs.
The effect of adrenaline on the contraction of human muscle
Authors: Marsden C. D. , Meadows J. C. 
Published: December 2014

1. Infusions of adrenaline in physiological amounts alter human muscle contractions evoked by nerve stimulation.2. Adrenaline shortens the duration of the slow calf muscle twitch, but has no effect on the fast twitch of adductor pollicis.3. Adrenaline decreases unfused tetanic tension and increases the oscillation of tension in 10/sec tetani of calf muscle and adductor pollicis. The usual rise of tension and decrease in oscillation in unfused tetani (‘ramp’ phenomenon) is abolished.4. Adrenaline has no effect on maximal tetanic tension or maximal rate of rise of tension in a fused tetanus of adductor pollicis.5. The effects of adrenaline on human muscle are due to stimulation of β‐adrenotropic receptors, for they are abolished by the β‐adrenotropic antagonist
DL‐propranolol (but not by
D‐propranolol), and are mimicked by isoprenaline but not by noradrenaline.6. The effect of adrenaline on adductor pollicis is abolished by local β‐blockade of one arm with intra‐arterial
DL‐propranolol, indicating that the responsible β‐receptors lie peripherally.7. The changes in muscle contraction observed cannot be explained by altered muscle temperature, for this falls during adrenaline infusion; nor are they due to an action on neuromuscular transmission, for these small doses of adrenaline do not affect the muscle action potential. The evidence points to a direct action of adrenaline on muscle.
Oxygen intake in track and treadmill running with observations on the effect of air resistance
Authors: Pugh L. G. C. E. 
Published: December 2014

1. The relation of V̇O2 and speed was measured on seven athletes running on a cinder track and an all‐weather track. The results were compared with similar observations on four athletes running on a treadmill.2. In treadmill running the relation was linear and the zero intercept coincided with resting V̇O2.3. In track running the relation was curvilinear, but was adequately represented by a linear regression over a range of speeds extending from 8·0 km/hr (2·2 m/sec) to 21·5 km/hr (6·0 m/sec). The slope of this line was substantially steeper than the regression line slope for treadmill running.4. The influence of air resistance in running was estimated from measurements of V̇O2 on a subject running on a treadmill at constant speed against wind of varying velocity.5. The extra O2 intake (ΔV̇O2) associated with wind increased as the square of wind velocity. If wind velocity and running velocity are equal, as in running on a track in calm air, ΔV̇O2 will increase as the cube of velocity.6. It was estimated that the energy cost of overcoming air resistance in track running is about 8% of total energy cost at 21·5 km/hr (5000 m races) and 16% for sprinting 100 m in 10·0 sec.
Conduction velocity in myelinated nerve fibres of Xenopus laevis
Authors: Hutchinson N. A. , Koles Z. J. , Smith R. S. 
Published: December 2014

1. The relationship between conduction velocity and nerve diameter in single myelinated nerve fibres from Xenopus laevis was measured and was found to be linear.2. The relationship between conduction velocity and temperature in nerve fibres of various diameters was measured over the range 15–30° C and was found to be linear for each fibre.3. The slope of the conduction velocity—temperature relationship was directly proportional to the diameter of the nerve fibre.4. The form of the conduction velocity—temperature relationship was determined by numerical solution of the Frankenhaeuser—Huxley equations for the case of a propagated action potential. The computation predicted that conduction velocity is a linear function of temperature over the range studied.
Role of naso‐buccal passages in thermoregulation in sheep
Authors: Phillips G. D. , Raghavan G. V. 
Published: December 2014

1. Experiments with a face‐mask in which the temperature of the air in the face‐mask was raised to 40° C while the ambient temperature in the chamber was maintained at 20° C, resulted in a marked increase in respiratory frequency and a slight decline in carotid blood temperature of unshorn sheep. Partially shorn sheep showed only small respiratory responses.2. Localized infra‐red irradiation of the naso‐buccal area of unshorn sheep also resulted in an increased respiratory rate.3. It is suggested that the initiation of polypnoea during infra‐red irradiation of the naso‐buccal region and following rise in the temperature of the air in the face‐mask is due to stimulation of warm receptors in the upper respiratory tract.4. Cooling the naso‐buccal air in the face‐mask to 10° C after thermal polypnoea had been established at an ambient temperature of 40° C resulted in a moderate decline of 30–40 respirations/min. This decline was attributed to the stimulation of cold receptors located in the upper respiratory tract.