scholarly journals Active nitrogen of long duration, law of decay, and of increased brightness on compression

1935 ◽  
Vol 151 (874) ◽  
pp. 567-584 ◽  
Keyword(s):  
Small Area ◽  
Copper Surface ◽  
Metal Electrodes ◽  
Experimental Conditions ◽  
Active Nitrogen ◽  
Mercury Surface ◽  
Long Duration ◽  
Unfavourable Effect ◽  
The Subject ◽  
Low Pressures

1-Active Nitrogen-Influence of Vessel Walls on the Duration The length of time for which the afterglow associated with active nitrogen remains perceptible varies very greatly under different experimental conditions; and, what is more important, if we start from a given luminosity per cc of the gas, the integrated amount of light emitted before the luminosity sinks to zero varies also. This is connected with the fact that the walls of the certain gaseous impurities may have an unfavourable effect. In other words, the active nitrogen may go out of existence either by a luminous or a non-luminous reaction. If it is desired to study the homogeneous luminous reaction, then it becomes important to eliminate the other as far as possible. So far as I am aware, no systematic attempt has ever been made to do this, though many writers have referred to the subject. The electrodelss ring discharge at low pressures is suited for the production of active nitrogen, and it has the advantage that no metal electrodes need be introduced. An oxidized copper surface, even of very small area, immediately destroys the afterglow when introduced into it, and a clean (freshly formed) mercury surface is attacked with formation of nitride. In view of these facts it seemed best to avoid metal, though more information would be desirable.

scholarly journals V.—Note on an Undescribed Area of Lower Greensand or Vectian in Dorset

1891 ◽  
Vol 8 (10) ◽  
pp. 456-458 ◽  
Author(s):  
A. J. Jukes-Browne
Keyword(s):  
Lower Cretaceous ◽  
Small Area ◽  
Upper Cretaceous ◽  
The Other ◽  
Present Communication ◽  
The Subject ◽  
Geological Magazine

Until recently no outcrop of the Vectian or Lower Greensand was known to occur between Lulworth on the coast of Dorset and the neighbourhood of Devizes in Wiltshire. It was supposed that, with the exception of a small area of Wealden in the Vale of Wardour, the whole of the Lower Cretaceous Series in Dorset and South Wilts was concealed and buried beneath the overlapping Upper Cretaceous strata. A recent examination of this district however has revealed two areas where the Vectian sands emerge from beneath the Gault. One of these has already been indicated in the pages of the Geological Magazine; the other is the subject of the present communication.

Contralateral coordination and retargeting of limb movements during scratching in the locust

1998 ◽  
Vol 201 (13) ◽  
pp. 2021-2032 ◽  
Author(s):  
T Matheson
Keyword(s):  
Nerve Cord ◽  
Tactile Stimulation ◽  
Schistocerca Gregaria ◽  
Limb Movements ◽  
Single Cycle ◽  
Experimental Conditions ◽  
The Subject ◽  
The Common ◽  
Peripheral Sensory ◽  
Stimulus Site

Locusts, Schistocerca gregaria, in common with many limbed vertebrates, can make directed scratching movements in response to tactile stimulation. For instance, stimulation of different sites on a wing elicits different movements that are accurately targeted so that the hindleg tarsus passes across the stimulus site. I have analysed these limb movements to define the ability of a locust to target stimulus sites correctly under a range of experimental conditions. In particular, I describe aspects of the behaviour that reveal possible neuronal pathways underlying the responses. These neuronal pathways will be the subject of further physiological analyses. Limb targeting during scratching is continuously graded in form; different patterns of movement are not separated by sharp transitions. The computation of limb trajectory takes into account the starting posture of the hindleg, so that different trajectories can be used to reach a common stimulus site from different starting postures. Moreover, the trajectories of the two hindlegs moving simultaneously from different starting postures in response to a single stimulus can be different, so that their tarsi converge onto the common stimulus site. Different trajectories can be used to reach a common stimulus site from the same start posture. Targeting information from a forewing is passed not only down the nerve cord to the ipsilateral hindleg but also across the nerve cord, so that the contralateral hindleg can also make directed movements. This contralateral transmission does not rely on peripheral sensory feedback. When the stimulus site moves during a rhythmical scratch, the targeting of subsequent cycles reflects this change. Both ipsilateral and contralateral hindlegs can retarget their movements. The trajectory of a single cycle of scratching directed towards a particular stimulus site can be modified after it has begun, so that the tarsus is redirected towards a new stimulus site.

scholarly journals On the measurement of the dielectric constants of liquids, with a determination of the dielectric constant of benzene

1929 ◽  
Vol 123 (792) ◽  
pp. 664-685 ◽  
Keyword(s):  
Dielectric Constant ◽  
Physical Properties ◽  
Dielectric Constants ◽  
Experimental Conditions ◽  
The Past ◽  
A Value ◽  
The Subject ◽  
Important Indication

It has long been recognised that the dielectric constant of a substance gives an important indication of its constitution, and the classical papers of Nernst and Drude giving methods for the determination of dielectric constants, have been followed by a long series of papers giving the dielectric constants of several hundreds of pure liquids and solutions. Since the publication of Debye’s dipole theory in 1912, the literature of the subject has become even more voluminous than before. In surveying the mass of data one is struck by the very large discrepancies which exist in the values obtained by different observers for any one substance, and it is very difficult to decide whether they are due to the difficulty of pre­paring and purifying the substance, differences in experimental conditions such as frequency of the applied E. M. F., or errors in the methods of measure­ment. In order to make it possible to compare the results of different observers, and to provide a fundamental basis for new measurements, it is important that the value of at least one standard liquid should be known with unquestion­able accuracy. The object of the present investigation was to provide such a value. Benzene was chosen as the standard liquid since it has been very widely used in the past, and it is used as a standard in the measurement of other physical properties.

A new local feedback model of the saccadic burst generator

1988 ◽  
Vol 59 (5) ◽  
pp. 1455-1475 ◽  
Author(s):  
C. A. Scudder
Keyword(s):  
Target Position ◽  
Burst Frequency ◽  
Experimental Conditions ◽  
Burst Neurons ◽  
Feedback Model ◽  
Long Duration ◽  
Important Input ◽  
Local Feedback ◽  
The Brain ◽  
Omnipause Neurons

1. To accommodate the finding that the superior colliculus is an important input to the brain stem pathways that generate saccades (the saccadic burst generator), a new model of the burst generator is proposed. Unlike the model of Robinson (61) from which it was derived, the model attempts to match a neural replica of change in eye position, which is the output of the burst generator, to a neural replica of change in target position, which is the output of the colliculus and the input to the model. 2. The elements of the model correspond to neurons known or thought to be associated with the actual primate saccadic burst generator and are mostly connected together in accord with the results of anatomical and physiological experiments. 3. The model was simulated on a digital computer to compare its behavior with that of the actual burst generator under normal and experimental conditions. Simulated peak burst frequency and saccade duration matched that obtained from monkey excitatory burst neurons and inhibitory burst neurons for saccades up to 15 degrees but did not match at larger sizes; stimulation of the omnipause neurons caused an interruption of the saccade, and the saccade resumed at the end of stimulation as in actual data; the model can generate the abnormally long-duration saccades seen under decreased alertness or various pathologies by changing the burst generator inputs and without having to change any properties of the neurons themselves or their connections; a simulated horizontal and vertical burst generator pair connected only through the omnipause neurons can generate realistic oblique saccades. 4. The implications of the model for higher-order control of the saccadic burst generator are discussed.

scholarly journals THE EFFECTS OF VARIATIONS IN THE CONCENTRATION OF OXYGEN AND OF GLUCOSE ON DARK ADAPTATION

1940 ◽  
Vol 24 (1) ◽  
pp. 69-98 ◽  
Author(s):  
R. A. McFarland ◽  
W. H. Forbes
Keyword(s):  
Blood Sugar ◽  
Dark Adaptation ◽  
Control Level ◽  
Light Sensitivity ◽  
Individual Variability ◽  
Similar Degree ◽  
Base Line ◽  
Low Oxygen ◽  
Experimental Conditions ◽  
The Subject

In this study we have analyzed the effects of variations in the concentrations of oxygen and of blood sugar on light sensitivity; i.e. dark adaptation. The experiments were carried out in an air-conditioned light-proof chamber where the concentrations of oxygen could be changed by dilution with nitrogen or by inhaling oxygen from a cylinder. The blood sugar was lowered by the injection of insulin and raised by the ingestion of glucose. The dark adaptation curves were plotted from data secured with an apparatus built according to specifications outlined by Hecht and Shlaer. During each experiment, observations were first made in normal air with the subject under basal conditions followed by one, and in most instances two, periods under the desired experimental conditions involving either anoxia or hyper- or hypoglycemia or variations in both the oxygen tension and blood sugar at the same time. 1. Dark adaptation curves were plotted (threshold against time) in normal air and compared with those obtained while inhaling lowered concentrations of oxygen. A decrease in sensitivity was observed with lowered oxygen tensions. Both the rod and cone portions of the curves were influenced in a similar way. These effects were counteracted by inhaling oxygen, the final rod thresholds returning to about the level of the normal base line in air or even below it within 2 to 3 minutes. The impairment was greatest for those with a poorer tolerance for low O2. Both the inter- and intra-individual variability in thresholds increased significantly at the highest altitude. 2. In a second series of tests control curves were obtained in normal air. Then while each subject remained dark adapted, the concentrations of oxygen were gradually decreased. The regeneration of visual purple was apparently complete during the 40 minutes of dark adaptation, yet in each case the thresholds continued to rise in direct proportion to the degree of anoxia. The inhalation of oxygen from a cylinder quickly counteracted the effects for the thresholds returned to the original control level within 2 to 3 minutes. 3. In experiments where the blood sugar was raised by the ingestion of glucose in normal air, no significant changes in the thresholds were observed except when the blood sugar was rapidly falling toward the end of the glucose tolerance tests. However, when glucose was ingested at the end of an experiment in low oxygen, while the subject remained dark adapted, the effects of the anoxia were largely counteracted within 6 to 8 minutes. 4. The influence of low blood sugar on light sensitivity was then studied by injecting insulin. The thresholds were raised as soon as the effects of the insulin produced a fall in the blood sugar. When the subjects inhaled oxygen the thresholds were lowered. Then when the oxygen was withdrawn so that the subject was breathing normal air, the thresholds rose again within 1 to 2 minutes. Finally, if the blood sugar was raised by ingesting glucose, the average threshold fell to the original control level or even below it. 5. The combined effects of low oxygen and low blood sugar on light sensitivity were studied in one subject (W. F.). These effects appeared to be greater than when a similar degree of anoxia or hypoglycemia was brought about separately. 6. In a series of experiments on ten subjects the dark adaptation curves were obtained both in the basal state and after a normal breakfast. In nine of the ten subjects, the food increased the sensitivity of the subjects to light. 7. The experiments reported above lend support to the hypothesis that both anoxia and hypoglycemia produce their effects on light sensitivity in essentially the same way; namely, by slowing the oxidative processes. Consequently the effects of anoxia may be ameliorated by giving glucose and the effects of hypoglycemia by inhaling oxygen. In our opinion, the changes may be attributed directly to the effects on the nervous tissue of the visual mechanism and the brain rather than on the photochemical processes of the retina.

scholarly journals Recombination and the long duration of the Balmer spectrum

1946 ◽  
Vol 186 (1005) ◽  
pp. 236-241 ◽  
Keyword(s):  
Electric Field ◽  
Experimental Conditions ◽  
Balmer Series ◽  
Electrodeless Discharge ◽  
Long Duration

Lord Rayleigh has recently found that the time of relaxation of the Balmer series of hydrogen excited by an electrodeless discharge is at least of the order 10 -5 sec. after it has been blown out of the electric field by its own expansion. Following Page, it is assumed that the luminosity is due to recombination of electrons with protons, and then Kramers’s theory yields halfvalue periods certainly larger than 10 -5 sec. under the special experimental conditions. Difficulties in the application of this theory raised by Cillié and Page are briefly discussed.

Evaluation of the Arousal Level in Motorcar Driving Using Skin Potential Level: Changes in Skin Potential Level under Various Driving Conditions

1994 ◽  
Vol 6 (1) ◽  
pp. 2-8
Author(s):  
Chiaki Nishimura ◽  
◽  
Akio Kosaka ◽  
Kazuko Terada ◽  
Shuji Yoshizawa ◽  
...  
Keyword(s):  
Arousal Level ◽  
Experimental Conditions ◽  
Skin Potential ◽  
Traffic Conditions ◽  
Palmar Surface ◽  
The Subject ◽  
Range Correction ◽  
Maximal Reduction ◽  
Electro Negativity ◽  
Potential Level

The skin potential level (SPL) on the palmar surface is known to reflect the level of arousal in some behavioral situations. In this paper, this relationship was ascertained in motorcar driving. The SPL was measured for two subjects on ordinary roads under various experimental conditions. The results show that (1) in general, the SPL was kept at high negative levels, and (2) the SPL reduced its electro-negativity when traffic conditions around the motorcar required less tension of the subjects. In the case, the arousal level of the subjects was thought to be low. From these results, it is concluded that the SPL has sufficient sensitivity in detecting the decrease of the arousal level in motorcar driving. In the data processing of the SPL, a range correction was effective in reducing individual differences. The observed maximal reduction of electro-negativity was 80%, in which case the subject complained of serious drowsiness. The SPL was kept at high negative levels when the driver performed an additional light task or conversed with an assistant driver.

12. The Mineral Requirements of Dairy Cattle

1930 ◽  
Vol 2 (1) ◽  
pp. 1-37 ◽  
Author(s):  
J. A. Crichton
Keyword(s):  
Milk Yield ◽  
Mineral Content ◽  
Mineral Metabolism ◽  
Common Knowledge ◽  
Practical Importance ◽  
Mineral Elements ◽  
Knowledge Based ◽  
Feeding Experiments ◽  
Long Duration ◽  
The Subject

The most important fact brought out by a review of the present position of our knowledge of mineral metabolism and the mineral requirements in the dairy cow is, that, in spite of the amount of work which has been done on the subject, our information is exceedingly scanty. We know that deficiency of calcium or phosphorus may affect rate of growth, milk yield, breeding capacity, and in all probability susceptibility to certain diseases. We know also that even on what are counted good rations, depletion of the tissues, especially of calcium, in heavy milking cows during lactation is common. In some districts deficiency of iodine causes pathological conditions, and it is common knowledge based on practical observations that even on pasture there is liable to be a deficiency of chlorine. With regard to the possibility of deficiencies of other mineral elements and the effect of such deficiencies on the health and milk production of cows, we have not yet even begun to accumulate knowledge. It is thus impossible to make a final pronouncement with regard to any of the main problems. We need many more data on the metabolism of minerals in the lactating animal and on feeding experiments of long duration with rations of different mineral content. Such information as we have, however, suggests that the subject is one of great potential practical importance, and that if the necessary information were available it might be applied to the more economical production of milk, both by increasing milk yield and by reducing mortality from disease.With regard to the information we do possess, much of it is not immediately applicable in practice because the data have been accumulated with diets and under conditions which have no parallel in practice. The following conclusions sum up in a general way the practical bearing of our present knowledge.

scholarly journals The diamagnetic susceptibilities of salts forming ions with inert gas configurations - Part I—The halides of sodium and potassium

1934 ◽  
Vol 147 (860) ◽  
pp. 88-100 ◽  
Keyword(s):  
Diamagnetic Susceptibility ◽  
Theoretical Work ◽  
Systematic Investigation ◽  
Inert Gas ◽  
Experimental Conditions ◽  
The Past ◽  
The Subject ◽  
Complete Investigation ◽  
Sodium And Potassium ◽  
Quantitative Nature

Although the subject of diamagnetic susceptibility has attracted the attention of many experimental and theoretical investigators during the past decade, it is remarkable that no complete systematic investigation of the susceptibilities of salts forming ions with inert gas configurations has been made. As a result, in comparing experimental and theoretical work, results for various salts obtained by quite different methods are used in conjunction with one another, and it is hardly surprising that the agreement should be of an approximate quantitative nature only in view of the wide discordance of the experimental results. The work of Ikenmeyer is the most complete investigation, but here the susceptibilities of certain salts, notably the fluorides, have not been measured. This is a serious omission for the data upon fluorides should prove to be amongst the most interesting. The present investigation is part of an attempt to obtain a series of results under the same experimental conditions and with the same apparatus, in order that the comparative values so obtained may be as accurate as possible.

scholarly journals III - The hydatids of Morgagni under normal and experimental conditions

1937 ◽  
Vol 228 (550) ◽  
pp. 147-172 ◽  
Keyword(s):  
Experimental Work ◽  
Tunica Vaginalis ◽  
Experimental Conditions ◽  
The Subject

Anatomical investigations of the appendages attached to the testis and epididymis began with enquiries into the origin of the fluid found in hydrocoeles. Morgagni (1682-1771), who was the first to draw attention to these minute structures, was opposed to the hypothesis that the tunica vaginalis is a secreting membrane. In place of that view, he advocated the opinion (1769) that the fluid is derived from ruptured testicular and epididymal hydatids. The several investigations which followed Morgagni’s observations showed clearly that his designation of these bodies as hydatids is fundamentally incorrect. Partly because of alternative descriptions advanced by subsequent workers, and partly because the subject has not been seriously considered since the earlier years of the present century, textbook descriptions of the testicular and epididymal appendages vary greatly with respect to the number, nomenclature, topography and embryological significance of these bodies. The following synthesis of available views regarding the hydatids in man provides a necessary background to the consideration of the corresponding structures in monkeys, from which the material for the experimental work recorded in this paper was obtained.

Sign in / Sign up

Export Citation Format

Share Document