scholarly journals A study of the interaction of radio waves

1948 ◽  
Vol 193 (1034) ◽  
pp. 311-343 ◽  
Keyword(s):  
Wave Interaction ◽  
The Other ◽  
Radio Waves ◽  
Absorption Process ◽  
Absorption Mechanism ◽  
Linear Absorption ◽  
Standard Nomenclature ◽  
Ionospheric Absorption ◽  
Series Of Experiments ◽  
Crucial Experiments

Experiments are described in which the phenomenon of wave-interaction (‘Luxembourg effect’) is used to provide information about the height at which radio waves of different frequencies are absorbed in the ionosphere. It is first, demonstrated by two crucial experiments that the absorption mechanism suggested by Bailey & Martyn (1934 a and b ) is the true one. Measurements of the phase of the modulation transferred from one wave to the other by the non-linear absorption process in the ionosphere are described; and it is shown how, by measuring this phase at different modulation frequencies, it is possible to locate the region where the interaction occurs. The results of a series of experiments summarized in tables 2, 3 a and 3 b and figures 8 and 9 are discussed. The conclusion is reached that the frequency with which electrons collide with neutral molecules at a height of about 85 km. is of the order 5 x 10 5 sec. -1 , and that this is the height near which the main absorption of waves of frequency 1 Mcyc./sec. and 200 kcyc./sec. are absorbed at night. Waves of frequency 90 and 68 kcyc./sec. are absorbed, and possibly also reflected, below this level. With the approach of dawn the regions responsible for absorbing 1 Mcyc./sec. and 200 kcyc./sec. waves drift apart. The theory of Bailey & Martyn (1934 b ) and Bailey (1937 a ) is related to modern theories of ionospheric absorption and is restated with the standard nomenclature of Appleton’s magneto-ionic theory.

scholarly journals VIII. On the descending degenerations which follow lesions of the gyrus marginalis and gyrus fornicatus in monkeys

1889 ◽  
Vol 180 ◽  
pp. 331-354
Keyword(s):  
The Other ◽  
Post Mortem ◽  
Cerebral Lesions ◽  
Series Of Experiments ◽  
The Government ◽  
Government Grant

The following paper contains the record of an investigation into the degenerations which follow lesions of the gyrus marginalis and gyrus fornicatus in Monkeys. The work has been carried on under my direction by Mr. France, with the aid of a grant from the Government Grant Fund, and represents part of a long investigation into the degenerations which follow artificially produced cerebral lesions, the material for which has been furnished by cases operated upon in conjunction respectively with Professor V. Horsley and Dr. Sanger Brown. These cases and the physiological results of the operations have already been published in the ‘Philosophical Transactions.’ The experiments here dealt with, twelve in number, comprise only the lesions of the gyrus marginalis and gyrus fornicatus, and, with one exception (case 12), are taken from the series of experiments performed in conjunction with Mr. Horsley. Of the twelve cases, six were of removal, or attempted removal, of the gyrus marginalis, and six of removal, or attempted removal, of the gyrus fornicatus. But in only one or two instances was the lesion, as determined by post-mortem examination, exactly limited to the convolution which it was attempted to remove, for in most cases the adjacent gyrus was to a certain extent involved in the injury. This was especially the case when removal of the gyrus fornicatus had been attempted, on account of its deep situation, and the difficulty of getting at it without some manipulation of the superjacent gyrus. Nevertheless, the removal of one or the other gyrus was sufficiently complete in all the cases here selected to produce characteristic symptoms and characteristic descending degenerations.

scholarly journals XXI. On the construction of a new calorimeter for determining the radiating powers of surfaces in air; and its application to the surfaces of various mineral substances

1860 ◽  
Vol 150 ◽  
pp. 379-408
Keyword(s):  
Surrounding Medium ◽  
The Other ◽  
Absolute Amount ◽  
Present Communication ◽  
Atmospheric Air ◽  
Glass Bulb ◽  
Heated Body ◽  
Series Of Experiments ◽  
Quantity Of Heat ◽  
Limited Induction

When my paper on the Conductivity of various Substances was presented to the Society, it was intimated to me on the part of the Council of the Society, that it might be advisable to determine absolute instead of relative conductivities, the latter being alone attempted in my previous experiments. It has been partly in consequence of this intimation, as well as from the desire to make my investigations the more complete, that I have given my attention to the construction of a calorimeter which might serve for this purpose. The present communication contains a description of this instrument, with the results which it has enabled me to obtain respecting the absolute quantities of heat which emanate from the surfaces of certain substances under given conditions. 1. When a body is placed in atmospheric air (or any gas), the quantity of heat which is lost from its surface in a given time, when its temperature is higher than that of the surrounding medium, will be greater than if it were placed in a vacuum, other conditions remaining unaltered. In the latter case the heat escapes by simple radiation; in the other case a portion of the heat also escapes in consequence of the contact of the air with the surface of the heated body. Dulong and Petit ascertained by a careful series of experiments, the laws according to which the mercury contained in the bulb of a thermometer cools, or those which govern the quantity of heat which escapes from the surface of the containing bulb, when placed in a vacuum, in air, or in several kinds of gases. These experiments were made with the glass bulb naked, and also when it was silvered, so that the laws of radiation which they established were strictly in reference only to surfaces of glass and those of silver. Certain laws were identical in both these cases, and hence it was concluded, though by a limited induction, that the same laws were applicable to all other surfaces. They did not, however, give the absolute quantity of heat which, under given circumstances, and in a given time, emanates from the surfaces of the glass or silver with which they experimented. The instrument which I have constructed gives very easily this absolute amount of heat, as I believe, with very approximate accuracy.

Specification of retinotectal connexions during development of the toad Xenopus laevis

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 77-92
Author(s):  
S. C. Sharma ◽  
J. G. Hollyfield
Keyword(s):  
Xenopus Laevis ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Optic Tectum ◽  
Ganglion Cells ◽  
The Other ◽  
Retinal Ganglion ◽  
Visual Projection ◽  
Series Of Experiments ◽  
The Right

The specification of central connexions of retinal ganglion cells was studied in Xenopus laevis. In one series of experiments, the right eye primordium was rotated 180° at embryonic stages 24–32. In the other series, the left eye was transplanted into the right orbit, and vice versa, with either 0° or 180° rotation. After metamorphosis the visual projections from the operated eye to the contralateral optic tectum were mapped electrophysiologically and compared with the normal retinotectal map. In all cases the visual projection map was rotated through the same angle as was indicated by the position of the choroidal fissure. The left eye exchanged into the right orbit retained its original axes and projected to the contralateral tectum. These results suggest that retinal ganglion cell connexions are specified before stage 24.

I. On the volumetric relations of ozone and the action of the electrical discharge on oxygen and other gases

1860 ◽  
Vol 10 ◽  
pp. 427-428 ◽  
Keyword(s):  
Electrical Discharge ◽  
The Other ◽  
Pure Oxygen ◽  
Silent Discharge ◽  
Gaseous Substance ◽  
Series Of Experiments ◽  
The One

This paper contains the full details of the authors’ experiments on the volumetric changes which occur in the formation of ozone. From three distinct series of experiments, performed by different methods, they show that when ozone is formed from pure oxygen by the action of the electrical discharge, a condensation takes place, as had already been announced in a former Note published in the 'Proceedings.’ But the condensation is much greater than the earlier experiments of the authors on the expansion by heat of electrolytic ozone had indicated. It is, in fact, so great, that if the allotropic view of the constitution of ozone be correct, the density of that body, as compared with oxygen, would be represented by a number corresponding to the density of a solid or liquid rather than that of a gaseous substance. This conclusion follows necessarily from the authors’ experiments, unless it be assumed that when ozone comes into contact with such substances as iodine, or a solution of iodide of potassium, one portion of it is changed back into common oxygen, while the remainder enters into combination, and that these portions are so related to one another, that the expansion due to the one is exactly equal to the contraction arising from the other. For the details of the experiments and of the methods of investigation employed, reference must be made to the original paper. The second part of the communication is devoted to the action of the silent discharge and of the electrical spark on other gases. Hydrogen and nitrogen undergo no change of volume when exposed to the action of either form of discharge. Cyanogen is readily decomposed by the spark, but presents so great a resistance to the passage of electricity, that the action of the silent discharge can scarcely be observed. Protoxide of nitrogen is readily attacked by both forms of discharge, with increase of volume and formation of nitrogen and hyponitric acid. Deutoxide of nitrogen exhibits the remarkable example of a gas which, under the action either of the silent discharge or of the spark, undergoes, like oxygen, a diminution of volume. It also is resolved into nitrogen and hyponitric acid. Carbonic oxide has given results of great interest; but the nature of the reaction has been only partially investigated. The silent discharge decomposes this gas with production of a substance of a bronze colour on the positive wire. The spark acts differently, destroying, as in the case of oxygen, the greater part of the contraction produced by the silent discharge. The authors are engaged in the further prosecution of this inquiry.

The Effect of Sand/Cement Ratio and Cement Grade on the Compressive Strength of Foam Concrete

2013 ◽  
Vol 405-408 ◽  
pp. 2933-2937
Author(s):  
Ji Chuan Geng ◽  
Kun Ni ◽  
Shan Qi Fang ◽  
Yun Xing Shi ◽  
Yi Ning Ding ◽  
...  
Keyword(s):  
Compressive Strength ◽  
The Other ◽  
Foam Concrete ◽  
Cement Ratio ◽  
Series Of Experiments

A series of experiments have been undertaken to investigate the effects, on compressive strength, of variable sand/cement ratios and cement grade. Ten mixtures of different s/c ratios used two kinds of cement were cast and the compressive strength at different curing ages was tested. The results indicate that the compressive strength gets lower as the s/c ratio increases for both 42.5R and 32.5R cement. For the mixtures used 32.5R cement, the 28-day compressive strength is pretty low for the s/c ratios of 1.5 and 2. The specimens used 42.5R cement have higher compressive strength than those with 32.5R cement. The compressive strength decreases from 42.5R to 32.5R cement are significantly smaller for the s/c ratios of 0.5 and 1 than the other three s/c ratios.

scholarly journals Phytoremediation as a Prospective Method for Rehabilitation of Areas Contaminated by Long-Term Sewage Sludge Storage: The Greek Experience

2017 ◽  
pp. 836-853
Author(s):  
N. Suchkova ◽  
E. Darakas ◽  
J. Ganoulis ◽  
Y. Vergeles
Keyword(s):  
Sewage Sludge ◽  
Plant Species ◽  
Shoot Growth ◽  
The Other ◽  
Control Treatment ◽  
Distilled Water ◽  
Series Of Experiments ◽  
And Control ◽  
Control Samples

In this work the suitability of several plant species for phytoremediation under natural and artificially installed conditions was studied. Brassica napus, Medicago sativa, Zea mays, Triticum aestivum, and Hordeum vulgare were grown in pots with sewage sludge from Sindos Main WWTP in Thessaloniki and from Sindos Industrial WWTP in Thessaloniki, Greece. The first series of experiments included comparing measurements of various parameters for the above mentioned plants and the sludge to those for control samples (the same plants growing in compost). It was shown that shoot growth was less reduced in T. aestivum and H. vulgare than in the other plant species studied. B. napus had lower germination tax, followed by M. sativa with the lowest germination tax. Generally B. napus, giving less biomass production than Z. mays and T. aestivum, is characterised by a higher ability to accumulate heavy metals like Cd, Cu, Ni, Pb, Zn, Cr, As and Hg. The second series of experiments included comparing measurements of various parameters of B. napus grown in sludge and treated each 7 days with metal solutions of Ni, Zn and Pb containing 10-2mg/l, 10-4mg/l, 10-6mg/l of each metal, to those for control plants treated with double distilled water. Results showed that shoot growth of B. napus were increased at treatments with lower concentrations of metals (10-6 mg/l) and control (treatment with d-distilled water). At the same time uptake of metal ions was increased with the concentration of the solution, i.e. at higher concentrations (10-2 mg/l). It is truly for Pb and Zn, transfer coefficient TC of which (indicates a plant’s potential to concentrate a metal) was quite high 15 % and 7 % correspondingly. It was noticed that B. napus has high ability to accumulate Cr, from the other hand it did not accumulate Ni (at present case).

scholarly journals A Discussion of Ionospheric Demodulation Near Gyro Frequency

1959 ◽  
Vol 12 (2) ◽  
pp. 157 ◽  
Author(s):  
GL Goodwin
Keyword(s):  
Modulation Frequency ◽  
Wave Interaction ◽  
Radio Waves ◽  
Large Magnitude ◽  
Reflected Wave ◽  
Made In

Observations made in Adelaide of the ionospheric demodulation of radio waves near gyro frequency at vertical incidence are discussed. The effect occurs in the region of about 90 km, and does not appear to decrease through dawn. An F-Iayer reflected wave is demodulated by unequal amounts during its two passages through the region. The large magnitude of the effect and its lack of dependence on modulation frequency seem to be inconsistent with the theory of wave interaction.

Rectal tone, distensibility, and perception: reproducibility and response to different distensions

1998 ◽  
Vol 274 (3) ◽  
pp. G584-G590 ◽  
Author(s):  
H. F. Hammer ◽  
S. F. Phillips ◽  
M. Camilleri ◽  
R. B. Hanson
Keyword(s):  
The Other ◽  
Rectal Distension ◽  
Abdominal Symptoms ◽  
Temporal Features ◽  
Balloon Distension ◽  
Basal Tone ◽  
Experimental Approaches ◽  
Series Of Experiments ◽  
Healthy Persons

Increasing interest is focusing on the role of intestinal tone, distensibility, and mechanosensation in the genesis of abdominal symptoms. Experimental approaches usually feature balloon distension of the bowel with measurements of perception, tone, and compliance and/or elastance; however, the methodologies are standardized incompletely. We examined the reproducibility of repeated assessments of sensory perception, basal tone, and compliance and/or elastance of the rectum during distension. We also evaluated the response to inflations that varied in regard to control of pressure or volume, pattern of distension, and rate of inflation. Five healthy volunteers were studied under two separate protocols. The first featured a series of experiments on each of 5 days; the other consisted of 2 separate days of study. Repeated distensions evoked reproducible responses of sensation and compliance and/or elastance on a single day, providing a conditioning distension preceded them. Day-to-day variability was also sufficiently small to allow valid comparisons to be made on different days in healthy persons. The configuration of the distension profile (phasic, staircase, or ramp) and the rate of inflation (from 1 to 40 ml/s) had little effect on distensibility or perception. Perceptions were sometimes transient and sometimes constant, but no relationship was found between these temporal features and the magnitude of the stimulus. These observations help provide a basis as to how the responses to rectal distension can be best studied.

Alternative developments of the theory of radio wave interaction

1953 ◽  
Vol 218 (1135) ◽  
pp. 520-536 ◽  
Keyword(s):  
Radio Wave ◽  
Wave Interaction ◽  
The Other ◽  
Laboratory Measurements ◽  
Alternative Development ◽  
Slow Electrons

New laboratory measurements on the motions of slow electrons in air suggest alternative developments in detail of the theory of radio wave interaction. One alternative development appears to be in better accordance with the results of measurements of radio wave interaction using large powers, than the other.

scholarly journals ASTROD I: Mission Concept and Venus Flybys

2005 ◽  
Vol 13 ◽  
pp. 921-921 ◽  
Author(s):  
Guangyu Li ◽  
Wei-Tou Ni ◽  
Chien-Jen Tang
Keyword(s):  
Gravitational Wave ◽  
Inertial Sensor ◽  
Initial Period ◽  
Test Mass ◽  
The Other ◽  
The Sun ◽  
Radio Waves ◽  
Spacecraft Control ◽  
Doppler Tracking ◽  
Relativistic Parameter

ASTROD I with one spacecraft ranging optically with ground stations is a first step for a full ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) mission. The goals are testing relativity with the relativistic parameter γ measured to 10~7, measuring solar-system parameters more precisely, and improving the present-day sensitivity for gravitational wave detection using Doppler tracking by radio waves. In this paper, we present the mission concept and the orbit design for ASTROD I with an emphasis on Venus flybys. The spacecraft is to be launched into an inner solar orbit with initial period about 290 days to encounter Venus twice to receive gravity-assistance for achieving shorter period (165 days or less) to reach the other side of the Sun for a sooner measurement of Shapiro time delay. For a launch on June 17, 2010, after two encounters with Venus, the orbital period can be shortened to 165 days and the spacecraft orbit reaches inside Mercury orbit. After about 400 days from launch, the spacecraft will arrive at the other side of the Sun and the relativistic parameter γ can be determined to 0.1 ppm or better. A simulation of the accuracy for determining the relativistic parameters γ and β, and the solar quadrupole parameter J2 gives 10−7, 10−7 and 10−8 for their respective uncertainties. In this simulation, we assume a 10 ps timing accuracy and 10−13 m/s2(Hz)1/2 at frequency f ~ 100μHz inertial sensor/accelerometer noise. Other orbits separated by synodic periods of Venus can readily be found. We discuss the sensitivity and noise reduction requirements, the atmosphere transmission noise, timing noise, spacecraft environmental noise, test-mass sensor back-action, and test mass-spacecraft control-loop noise and stiffness. In the second Venus flyby, the ASTROD I could also be swung into an elliptic 360-day orbit and stay near opposite side of the Sun for many good measurements of the Shapiro time delays — 19 times in 10 years. This is an interesting alternative. In the two Venus flybys, Venus multiple moments can be determined very precisely. In this paper, we also review ASTROD and discuss its gravitational-wave sensitivities.

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