Simultaneous Readings Research Articles

Galactic Structure from Photoelectric Distances of Early-Type Stars.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galactic Structure from Photoelectric Distances of Early-Type Stars. Beer, Arthur Abstract An analysis is presented of 3080 direct observations of the integrated light of the Hw region in 435 stars of types O and B in the northern sky and brighter than 7'~5. Two independent and consistent series of measurements were obtained, in 1960 and 1961, with the narrow-band spectrometer attached to the 36-inch reflector (f/18 coude' focus) of the Observatories, Cambridge, England. Using the pulse-counting method and two photomultipliers fed by appropriate windows in the focal-plane diaphragm of the grating, simultaneous readings were recorded of the intensity A due to the light through the Hw window at AA4325- 4357, as well as of the total intensity B due to two comparison windows placed at AX4255~289 and ~x4399-4427. At least two successive one-minute counts S per star were made in each of its nights, followed after about every third star by counts L of a standard lamp. The quotients S (B ) /L (B) over S(A)YL(A) gave the final H~ ratios R. On the average, each star was covered by 7.1 observations; each of these took an over-all telescope time of 7.4 min, inclusive of the lamp measurements spaced in the mean by 22.8 min. The program included 130 standard stars whose known absolute magnitudes were adopted for the present calibration, as a result of discussions by R. W. Petrie, Victoria 1953, by I. M. Kopylov, Crimea 1958, and by U. Sinnerstad, Stockholm 1961. The error of the mean of all the R values per star is t0.65%, corresponding to ft0rn.1 ~i~ absolute magnitude; and this, together with the intrinsic scatter within the whole of the calibration stars, leads to an estimated total error in luminosity of the order of about -~0.3 mag. Using measured color excesses to allow for interstellar absorption, the calibrated R values provide some three hundred new B-star distances. Their map- ping with respect to the 21-cm H I pattern of the Milky Way amplifies the author's conclusions from his recent equivalent-width measurements on some 420 spectrograms of 137 southern stars (Beer, A. Monthly Notices Roy. Asfron. Soc. 123, 191, 1961). New evidence is discussed, based on a close relationship between R and the MK luminosity system, comparisons with the concept of equivalent width, and the spatial distribution of clusters, associations, and H ii regions. The over-all picture has been correlated with proposed features of galactic structure and Milky Way arms. There are clearly great potentialities in further developments of this rapid observational method, particularly in view of the suggested large-scale applications to faint stars (e.g., by extending the counting time to several minutes), and it might well replace methods of detailed equivalent-width measurements by its speed, accuracy, and scope. Publication: The Astronomical Journal Pub Date: March 1962 DOI: 10.1086/108814 Bibcode: 1962AJ.....67Q.268B full text sources ADS |

Transmittance Measurements with an Interference Microscope

Interference microscopy has proved useful for the detection and measurement of path differences between an object and its surround. For objects which absorb a fraction of the incident light an additional valuable measurement is the transmittance. Modifications of the AO Baker interference microscope which permit its use as a double-beam microphotometer are described. In some of the systems it is possible to make simultaneous readings of transmittance and optical path. Both visual and photoelectric detection are possible, and in most of the systems light of a finite range of wavelengths may be used.

CHARTS FOR THE REDUCTION OF HEIGHTS FROM ANEROID READINGS BASED ON A STANDARD ATMOSPHERE AND A STANDARD LAPSE-RATE

Atmospheric pressure at a given point is measured by the weight of the vertical column of air on a uniform cross section above that point, which again depends on the density and chemical composition of the air and also on the temperature and the gravity value throughout the air column. The humidity is deduced from simultaneous readings of both wet and dry bulb thermometers and the air temperature is known from the dry bulb thermometer readings. Since the thermometer readings are obtainable only at the points of observation, some assumptions with regard to the temperature distribution in the air column are necessary for an accurate estimation of heights. The methods generally used for the reduction of aneroid readings are thus based on two assumptions—the isothermal and the lapse-rate. According to the isothermal assumption the temperature of the air column is considered uniform throughout. But this is contrary to observed facts; for normally up to a certain limiting height the telnperature of the air is observed to fall with increase of height at a more or less constant rate. The assumption of a standard lapse-rate does on the other hand conform more closely to nature and has therefore been now in general use. The relevant “Aneroid Tables Based on a Standard Atmosphere and a Standard Lapse-Rate” by H.M.S.O. provide an accurate and straightforward computation. But the main defect with these elaborate tables, as rightly indicated by Col. D. R. Crone in his article on “Heights by Aneroid Barometers” (E.S.R. ix, 69, 311–317),is that “these are not well suited for rapid entry and the method of correction for observed humidities with the wet and dry bulb is fiddling and not suited for mass reduction of readings”. Moreover, the tables are also defective in the sensethat they give rise to errors which become appreciable when dealing with higher altitudes.

CHARTS FOR THE REDUCTION OF HEIGHTS FROM ANEROID READINGS BASED ON A STANDARD ATMOSPHERE AND A STANDARD LAPSE-RATE

Atmospheric pressure at a given point is measured by the weight of the vertical column of air on a uniform cross section above that point, which again depends on the density and chemical composition of the air and also on the temperature and the gravity value throughout the air column. The humidity is deduced from simultaneous readings of both wet and dry bulb thermometers and the air temperature is known from the dry bulb thermometer readings. Since the thermometer readings are obtainable only at the points of observation, some assumptions with regard to the temperature distribution in the air column are necessary for an accurate estimation of heights. The methods generally used for the reduction of aneroid readings are thus based on two assumptions—the isothermal and the lapse-rate. According to the isothermal assumption the temperature of the air column is considered uniform throughout. But this is contrary to observed facts; for normally up to a certain limiting height the telnperature of the air is observed to fall with increase of height at a more or less constant rate. The assumption of a standard lapse-rate does on the other hand conform more closely to nature and has therefore been now in general use. The relevant “Aneroid Tables Based on a Standard Atmosphere and a Standard Lapse-Rate” by H.M.S.O. provide an accurate and straightforward computation. But the main defect with these elaborate tables, as rightly indicated by Col. D. R. Crone in his article on “Heights by Aneroid Barometers” (E.S.R. ix, 69, 311–317),is that “these are not well suited for rapid entry and the method of correction for observed humidities with the wet and dry bulb is fiddling and not suited for mass reduction of readings”. Moreover, the tables are also defective in the sensethat they give rise to errors which become appreciable when dealing with higher altitudes.

A Concentrator For Coordinated Corrosion Testing—A Contribution to the Work of NACE Technical Unit Committee T-4B on Corrosion of Cable Sheaths(1)

Abstract A concentrator for coordinated corrosion testing is described with which 19 simultaneous voltage readings can be made and which requires only one suitable voltmeter. The test box contains nineteen 4 mf capacitors, each of which accepts a charge from one of the external test circuits. At the desired instant of testing, the external circuits are all disconnected from the capacitors by the opening of gang-type relays. The voltage standing on each capacitor is then the corresponding voltage of the particular external circuit at the instant of disconnection. By means of a rotary switch, these voltages can be taken off in sequence and read out on a suitable external voltmeter at the convenience of the observer. The advantages derived from the use of the test box are as follows: (1) One meter observer can duplicate the work of up to nineteen observers on a meter-per-circuit basis; (2) One accurate voltmeter, having a high input impedance, can be selected for use rather than using an assemblage of 19 meters; (3) Despite fluctuation in measured voltages, the data obtained are more accurate than ordinarily can be obtained by direct readings of a meter on a test circuit; (4) The readings are truly simultaneous; (5) The use of one observer and one meter avoids variances formerly introduced by human characteristics and meter dissimilarities. 4.5.3

Electrical Resistance Networks for Beam and Column Problems

A similar formula in terms of the pitot tube reading shows that the overshoots indicated in Fig. 4 of reference 2 could be explained by a 1-5 per cent rise in static pressure pu in front of the pitot mouth. The preceding conjecture as well as the general up­ stream effect can be checked by taking simultaneous readings of pitot pressure at each y position and of static pressure from wall orifices under and slightly upstream of the pitot tip. If there is a demonstrable effect of upstream influence when a relatively large probe is outside of the layer, it would follow that similar or even larger effects could occur throughout the boundary layer and that some effect should be present for smaller probes. The presence of this effect and that due to the leading edge makes the near agreement with theory (which takes account of neither) in references 1, 2, and 3 the more remarkable. The question remains as to the non-dimensional parameters properly characterizing the above interference, with or without separation. Clearly, the probe height h has to be non-dimension alized with respect to some characteristic layer thickness in order to account for the observed effect of relative size. Just how this should be accomplished is not clear since it involves ques­ tions of pressure disturbance strength as function of y and the upstream viscous influence. The width of the probe must be significant since its increase means closer approach to the ob­ served two-dimensional critical pressure disturbance for sepa­ ration, P for instance, the upstream distance, s, through which a given (linearized) pressure disturbance at wall diminishes by a factor e1, measured with boundary layer thick­ ness as a unit, depends on the parameters approximately as fol­ lows :

Telemetering for system operation

The paper outlines the requirements of power-system control engineers in respect of telemetered intelligence to facilitate load dispatching. The problems associated with providing these continuous readings are dealt with, and a new electronic telemeter system is described which has advantages with regard to response and accuracy, and permits several simultaneous readings over a restricted bandwidth. Equipments of the type described have received field trials, and are in commercial use.

Effects of daily irradiation by fast neutrons on male fertility.

SINCE January 1, 1951, the smaller pile at Harwell has been used for irradiating CBA mice daily with fast neutrons. These were fission neutrons obtained by allowing thermal neutrons escaping from the graphite reflector to interact with uranium on the floor of the compartments in which the animals were housed. It is believed that less than 5 per cent of the biological effects produced was due to contaminating radiations. Dose-rates were measured with homogeneous ‘tissue’ (C0.15 H1.00 N0.00 O0.48) and hydrocarbon (CH) ionization chambers, an allowance being made for gamma-ray ionization by simultaneous readings with an argon chamber1.

A method for approximating the water content of soils

A procedure is described for calibrating fiberglas soil‐moisture units, and for preparing the tables required to convert resistance readings into inches of water. The shape and slope of the calibration curves are determined in the laboratory with the units placed in undisturbed soil samples. After the units have been placed in the field, the laboratory curves are translated laterally along the moisture axis by an amount determined through simultaneous field moisture samples and resistance readings. Regression equations characterizing the bulk density of the soil (as a function of moisture content and depth) are taken into account in converting soil‐moisture content from a per cent dry‐weight basis to inches of water. For thin horizons subject to large errors of measurement, a method is described for correcting the bulk‐density regression equation so as to conform with its corresponding calibration curve.

A METHOD TO DETERMINE THE PERIPHERAL ARTERIAL BLOOD PRESSURE IN THE MOUSE

Advantage has been taken of the relative transparency of the claw of the mouse to devise a method, here described, to measure the blood pressure in the animal's leg. Direct measurements of the systolic blood pressure from the carotid arteries of anesthetized mice have also been made. Simultaneous blood pressure readings by both these methods applied to the same animal showed close agreement. The systolic pressure ranged from 60 to 126 mm. Hg, according to the conditions.

METHODS OF SAMPLING VISIBLE RADIATION

There is perhaps no factor in the measurement of light which is more essential to the correct evaluation of light records and their correlation with various biological phenomena than the method of sampling of this radiation. Yet a survey of the literature on the subject discloses that no comprehensive tests have been made on the various possible physical arrangements of the sensitive surfaces of the receiving units and the degree of similarity which these various combinations will exhibit when checked by simultaneous readings of the same light station. We are all aware that the method so commonly used of exposing a single-plane receiving surface in one direction gives erratic results. Thus any one that has used any of the numerous exposure meters or illuminometers, having a flat surface as the receiving unit, knows from experience that a reading may vary from a few to perhaps almost 100 per cent, if the receiving unit is tilted a few degrees. This indicates a fundamental flaw in the sampling, for the original value will be found when the first position is again obtained. It would seem, therefore, that we must, if we are to use light records with any degree of success, have methods of sampling that make impossible these great fluctuations in value.

Factors Affecting Human Potassium Tolerance

A relation of the adrenal cortex to potassium metabolism is substantiated by the following facts. In experimental adrenal insufficiency, and in Addison's disease there is a definite rise in plasma potassium. This high potassium can be lowered by injection of adrenal cortex extract. In adrenal insufficiency there is an increased susceptibility to exogenous potassium, which has been quantitatively contrasted with normal potassium tolerance in experimental animals. The application of potassium tolerance determinations in the human is here briefly described. Solutions of potassium salts were administered by mouth, the dose being 10 mg. or 20 mg. of K per pound of body weight. Duplicate determinations of potassium were done for plasma and whole blood taken from the finger or ear immediately before taking the drink, and at intervals of 30 min., 1 hr., and 2 hr., thereafter. Simultaneous hematocrit readings enabled us to calculate the red cell potassium content. If similar amounts of potassium contained in food are taken, slower assimilation makes it necessary to continue the test for 5 hours. Seventeen human potassium tolerance curves on 12 individuals have been completed to date. Since this preliminary paper does not permit detailed discussion of all the curves, a few typical ones only are shown. The plasma K of normal individuals is not affected by ingestion of 10 mg. K per pound body weight (Graph 1). In Addison's disease, however, there is a rapid and very considerable rise in plasma K (Graph 2), much greater than can be accounted for by hemoconcentration. At the end of 2 hours both cell volume and plasma K are again approaching the initial values, but the red cell K content has increased, the increase being perhaps compensatory.

Concerning the Degree of Accuracy of the Gibson Method of Measuring the Flow of Water

Abstract The paper first discusses the limitations of various methods of measuring water which were in use when the Gibson method was first announced. These limitations of the current-meter method of flow measurement include: The effect of turbulent accessory motions which cause periodic velocity changes in the direction and magnitude of flow; the difficulty in obtaining readings close to the wall of the canal or closed conduit; and the necessity of determining the velocity at several points simultaneously due to temporary changes in distribution; and the expense involved in taking a number of such simultaneous readings. Reference is also made to the use of the pitot tube for taking readings close to the wall of the passage. The greater part of the paper, devoted to a discussion of the Gibson method of water measurement, includes the derivation of formulas involved in this method of water measurement, its limits of accuracy, and the errors which may arise in its use. These errors, due to (a) accessory motions, (b) to false valuation of friction, (c) to friction of the mercury column, and (d) to inertia of the mercury column, are presented with derived formulas and approximate values together with suggestions for minimizing them.

The Bionomics and Importance ofGlossina Longipalpis, Wied., in the Gold Coast

The Bionomics and Importance of<i>Glossina Longipalpis</i>, Wied., in the Gold Coast

INFLUENCE OF SCLEROTIC ARTERIAL WALL ON BLOOD PRESSURE MEASUREMENTS

Many studies have been made to determine whether a markedly sclerotic artery requires considerably more pressure to obliterate its lumen than a normal soft artery. The results of these investigations, largely derived from studies made directly on excised arteries, support the view that the pressure of but a few more millimeters of mercury is required to obliterate the lumen of a calcified artery. These findings apparently have not been verified in the living person. A person who had a markedly sclerotic radial artery in one arm and a soft radial artery in the other arm would offer an opportunity for an answer to this question by a comparison of simultaneous readings of the blood pressure in both arms. We have recently observed such a person, and the results of studies on him are presented in this paper. REVIEW OF THE LITERATURE An excellent summary of the literature on this subject

Analysis of the Energy Distribution in Speech1

The frequency distribution of energy in speech has been determined for six speakers, four men and two women, for a 50-syllable sentence of connected speech, and also for a list of 50 disconnected syllables. The speech was received by a condenser transmitter whose voltage output, amplified 3,000 fold, was impressed on the grids of twin single stage amplifiers. The unmodified output of one of these amplifiers was measured by a thermocouple and was a known function of the total energy received by the transmitter, corrections being made for the slight variation with frequency of the response of the circuit. The output of the other amplifier was limited by a series resonant circuit to a narrow band of frequencies, the energy in this band being measured by a second thermocouple. The damping of the resonant circuit was so chosen that sufficient resolving power and sufficient energy, sensitiveness were obtained over the range from 75 to 5,000 cycles per second; and 23 frequency settings were made to cover this range. For each syllable simultaneous readings were recorded on the two thermocouples at each frequency setting. The consecutive syllables were pronounced deliberately by each speaker, maintaining as nearly as possible the normal modulation of the voice. Corrections were applied to offset the unavoidable variations in total energy incidental to repetition of a given syllable. 13,800 observations were made for all speakers. The energy distribution curves obtained are essentially the same for connected as for disconnected speech, and indicate that differences between individuals are more important than variations due to the particular test material chosen. A composite curve drawn from the individual curves shows a great concentration of speech energy in the low frequencies, a result which would not be expected from data previously published by others. The actual results contain a factor due to standing waves between the speaker's mouth and the transmitter, a complication always present in telephoning; this could not be eliminated. The rate of energy output in speech for the normally modulated voice, was determined from the readings for total energy and was found to be about 125 ergs per second.

Analysis of the Energy Distribution in Speech

The frequency distribution of energy in speech has been determined for six speakers, four men and two women, for a 50-syllable sentence of connected speech, and also for a list of 50 disconnected syllables. The speech was received by a condenser transmitter whose voltage output, amplified 3,000 fold, was impressed on the grids of twin single stage amplifiers. The unmodified output of one of these amplifiers was measured by a thermocouple and was a known function of the total energy received by the transmitter, corrections being made for the slight variation with frequency of the response of the circuit. The output of the other amplifier was limited by a series resonant circuit to a narrow band of frequencies, the energy in this band being measured by a second thermocouple. The damping of the resonant circuit was so chosen that sufficient resolving power and sufficient energy-sensitiveness were obtained over the range from 75 to 5,000 cycles per second; and 23 frequency settings were made to cover this range. For each syllable simultaneous readings were recorded on the two thermocouples at each frequency setting. The consecutive syllables were pronounced deliberately by each speaker, maintaining as nearly as possible the normal modulation of the voice. Corrections were applied to offset the unavoidable variations in total energy incidental to repetition of a given syllable. 13,800 observations were made for all speakers. The energy distribution curves obtained are essentially the same for connected as for disconnected speech, and indicate that differences between individuals are more important than variations due to the particular test material chosen. A composite curve drawn from the individual curves shows a great concentration of speech energy in the low frequencies, a result which would not be expected from data previously published by others. The actual results contain a factor due to standing waves between the speaker's mouth and the transmitter, a complication always present in telephoning; this could not be eliminated.The rate of energy output in speech for the normally modulated voice, was determined from the readings for total energy and was found to be about 125 ergs per second.

On the Thermo-electric Properties of Solid Mercury

AbstractThis paper contained an account of a redetermination of the thermo-electric position of solid mercury, by a method described in a note read last session. The only difference was that, by the use of three galvanometers, simultaneous readings of the deflection due to the Hg-Fe circuit, and of the deflections due to thermoelectric circuits giving the temperatures of the two Hg-Fe junctions, were taken.

Geographical Notes

LIEUT. GREELY has been lecturing in Scotland on the Arctic Expedition of which he was the commander. At Dundee, on Monday night, having described the retreat from Discovery Harbour, Lady Franklin Bay, he went on to speak of the results of the Expedition, which could be done only in a general manner. The temperature observations, he remarked, were mainly important in determining the fact that Grinnell Land had the lowest mean temperature in the globe, about 4° F., or 20° C. below zero. This was in accordance with their expectations. The tidal observations, only roughly reduced by him at Conger, confirmed the work of 1875–76, but a large number of simultaneous readings at seven special stations in the Polar Sea, Robeson and Kennedy Channels, should enable tidal experts to determine quite accurately the shape and direction of the tidal wave, an important element in the theoretical determination of the configuration of lands and sea-bottom to the north. In Grinnell Land the discovery of coal not only at various points along the sea-coast, but at others in the interior, proved conclusively the changed climatic condition, as did the fossil forest found near Cape Baird in 81° 30′ N. Discoveries of Eskimo remains were of interest as showing the possible extent of this immigration of a new race into the Polar Basin. The Lieutenant next spoke of geographical discoveries. The furthest point seen by Beaumont was Cape Britannia, nearly 50 miles beyond the extreme point actually attained by that heroic officer. From Britannia Island Lieut. Lockwood and Sergeant Brainard pushed on 100 miles further, and passed a day and a half at Lockwood Island, the furthest point by land or sea ever attained by civilised man, in 83° 24′ N., 40° 46′ W. From an elevation of nearly 3000 feet it was evident that no land existed within a radius of sixty miles to the north or north-westward, but to the north-east the Greenland coast yet trended, ending to the eye at Cape Washington in 83° 35′ N. To Greenland was thus added 125 miles of new coast excluding the fiord lines, and from Cape May the mainland was carried a degree of latitude to the northward. In carrying Greenland 10° of longitude further to the eastward, Lieut. Lockwood left but, 16° for his successors to fill in. The new land is composed of high precipitous promontories along the coast, and equally broken country inland, in which but three glaciers were seen, none discharging. It was evident that the inland ice-cap of Greenland stopped far to the southward of the 82nd parallel. In short, there existed from Robeson and Kennedy Channels, westward to Greely Fiord and the Polar Sea, a series of fertile valleys clothed with vegetation of luxuriant growth, whereon were large herds of musk oxen. He desired to say a few words as to his discoveries concerning the much-talked-of palæocrystic ice, especially the floebergs from 100 to 1000 feet thick. The opinion advanced by Sir G. Nares that this ice formed over the Arctic Ocean was not borne out by facts, and he could not commit himself to the judgment that this sea was for ever unnavigable, for they knew that a quantity of the ice changed from year to year, and little of it was seen by Lieut. Lockwood to the northward of Cape May. Dr. Moss was certainly correct as to the universality of stratification in this ancient ice, and he concurred in the opinion that its salinity was due to effiorescence and infiltration, There was no doubt in his mind that these floes were simply detachments of slowly-moving glacial ice-caps from an ice-covered land in the neighbourhood of the Pole. Lieut. Lockwood found small floebergs, perhaps 100 to 200 feet thick, detached from the adjacent ice-caps. In Kane Sea he visited a floeberg a third of a mile wide, a quarter of a mile long, and from a fifth to a sixth of a mile thick. The proof as to its terrestrial origin no one would dispute; on its surface were two valleys about 30 feet deep, along which were the medial moraines of the glacier—fully 100 large stones polished and worn smooth in places by the parent ice. He thought it doubtful whether such an ice-cap increased by more than three or four inches yearly, so that from 3000 to 4000 years might easily have elapsed since the incipient birth of the berg in question. Lieut. Greely advocated future Arctic exploration in the direction of Franz Josef Land.

Scientific Report of the Austro-Hungarian North Polar Expedition of 1872–74*

II. MAGNETIC disturbances are closely connected with the Auiroræ; while in temperate zones they are the exception, they form the rule in Arctic regions, at least the instruments are almost in constant action. This is the case for the inclination, declination, and intensity needles. As long as the vessel was drifting, i.e. until October 1873, the fixed variation instruments could not be used; absolute determinations with Lamont's magnetic theodolite were made, and several “magnetic journals” (only declination-readings) were kept, but already when near Nowaja Semlja, Lieut. Weyprecht found out that on account of the constant disturbances these readings were of very little value, as they could not be compared with simultaneous readings of the variation-instruments. In November, as soon as it was ascertained that the ice-field which enclosed the ship had come to a standstill, Lieut. Weyprecht had snow-huts constructed in which he fixed the variation-instruments, the magnetic theodolite, the inclinometer for the absolute determinations, and the astronomical instruments. The three variation-instruments for declination, horizontal intensity, and inclination had been furnished to the expedition by Prof. Lamont, director of the Munich Observatory.