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1950 — The air motor as a cloud generatorAbstract
As a result of the current interest in theories designed to explain the processes whereby precipitation originates in clouds and, if possible, to devise methods of causing or initiating precipitation at times or places more desirable than those chosen by Nature, and particularly in view of certain assumptions made in the formulation of some of these theories, experiments are in progress to study the behaviour of water particles in a region of moist air and small water droplets such as is found in a cloud. For such experiments, some means of producing a cloud, preferably of controlled characteristics, in the … Read more
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1950 — Baudelaire, critique littéraireAbstract
Charles Baudelaire apparaît aujourd'hui comme le premier en date des poètes dits "modernes” et c'est parmi les poètes que le placent les anthologies contemporaines. Mais la renommée et l'influence de la poésie baudelairienne ont tendance à faire oublier le fait que Baudelaire fut également prosateur et que c’est à la prose qu'il dut ses premiers lauriers littéraires. La traduction des "Histoires Extraordinaires" d’Edgar Poe ne fut-elle pas son premier succès, et le plus indiscutable? Néanmoins, l’oeuvre en prose de Baudelaire ne représente qu'environ un quart de son oeuvre publiée — elle souffre donc d'un manque de volume par rapport à … Read more
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1950 — A follow-up study of brief service contacts in a child guidance centerAbstract
A follow-up study in the child guidance field usually stems from an interest in the amount of success met with in past treatment endeavours. From the material obtained by interviewing former patients or speaking to persons close to them it often becomes possible to arrive at some conclusions as to the benefits derived by these patients from past contacts with the clinic. Such a study may also serve to indicate the need for refinements in the present treatment approach which might add to the type of service given in the future. Read more
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1950 — Permeability of cellophane to liquids and vapoursAbstract
To interpret the permeability phenomena which are exhibited by cellulose, a knowledge of its structure and certain physical properties is essential. Although the present study is concerned with cellophane, which is a regenerated form of cellulose, it is preferable first to consider these aspects in native cellulose, and subsequently to describe the changes which occur as a result of regeneration. Read more
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1950 — Montaigne et les nouvelletésAbstract
Montaigne qui a le don d'être toujours nouveau et inattendu a, on serait tenté de dire, le don de l'ubiquité morale et philosophique aussi, de sorte que des esprits de tendances opposées ont pu se réclamer de lui avec la même facilité, et peut-être avec la même justification. La littérature sur Montaigne est volumineuse, et les commentaires en sont nombreux, de sorte qu'il faut beaucoup d'invention pour pouvoir trouver quelque chose de nouveau à dire sur notre auteur. Read more
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1950 — George Peele : the man and his workAbstract
Few of the people who paid a tester to attend Elizabeth’s coronation in 1558 could have realized that they were entering upon one of the most glorious periods in English history, the spacious days of Queen Elizabeth. They did not know that a new era was being born - the era of the defeat of the great Armada and the force of His Most Catholic Majesty, the era of Drake on the seas, Bacon in science, Gilbert and Harvey and their discoveries, Shakespeare in the drama. Read more
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1950 — The effect of pH on the agglutination of H and O suspensions of Salmonella typhosa in human and rabbit antiseraAbstract
The Laboratory of Hygiene, Department of National Health and Welfare, at the request of the Directors of the Provincial Laboratories, undertook to supply each of these laboratories with H and O suspensions of the following species in the genus Salmonella: S. typhosa, S. paratyphosa A, S. paratyphosa B, S. paratyphosa C, and S. cholerae-suis var. Kunzendorf, to be used in their routine widal tests. Read more
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1950 — The Hay river limestone, Northwest territoriesAbstract
During the latter part of the 1949 field season, the author served as geologist on a California Standard Company field party which was sent to the Northwest Territories to make an examination of the Upper Devonian limestone strata exposed along the Hay river. The objects of this survey were: (1) to further the completion of the California Standard Company's geological map of possible "petroleum bearing formations in northern Alberta and the Northwest Territories, and, (2) to attempt a correlation of the Hay River limestone formation with the petroliferous limestones underlying Leduc, Alberta. The thesis of this paper is a detailed … Read more
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1950 — Some investigations into the properties of a double-stream, microwave amplifierAbstract
The original theory of J.R. Pierce and A.V. Haeff pertaining to the problem of the existence of waves within a narrow beam of electrons of two different average velocities, is discussed. The theory is then extended to the case of wide beams separated by a finite distance. A special case of this theory is then considered, that of a wide pencil of two superimposed streams and the variation of signal amplification that may occur under suitable conditions is studied, as a function of beam width. The results indicate considerable discrepancies between the two theories in cases of narrow beams. As … Read more
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1950 — Geology of the Balachey Lake area, Northwest TerritoriesAbstract
During the 1947 field season the northern portion of the Camsell River Map area was mapped at a scale of two miles to one inch, by W. H. Parsons and the writer for the Geological Survey of Canada, the southern portion of the area having been completed the previous year by C. S. Lord (15) This paper deals with the northwest quarter of the "Camsell River Map Sheet" because of its geological end economical importance. Read more
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1950 — Part I. Synthesis of radioactive organic reagents. Part II. Attempted total synthesis in the estrogen series.Abstract
A study of the metabolism of steroid hormones is beset with many difficulties if the usual biochemical methods are to be applied. One of the most important difficulties, perhaps, is that the quantities of material present in animal tissues are usually extremely small. With the availability of radioactive isotopes, the problem was considerably simplified. In fact, if a steroidal hormone is made radioactive, it becomes a simple matter to determine its distribution in tissues and therefore much easier to obtain extracts indicative of its metabolic pathway. Read more
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1950 — Migration for employment : legal and institutional aspectsAbstract
From time immemorial population movements represented an important phenomenon in the life of man. Beginning with the instinctive movements of the primitive man and ending with the rational and purposeful migration of modern times, they held an important place in the development and history of mankind. Though the aim of this work is neither the study of the vast problem of population movements as such, nor the tracing of its historical development, it is necessary - in order to understand the legal implications of the movement of workers in the modern world - to give, at least a brief, survey … Read more
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1950 — Generation of short electrical impulses for gating miniature type vacuum tubes.Abstract
A particular application requires a voltage pulse of l/100th microsec. duration, 30 volts amplitude and 100 kc/sec. recurrence frequency. Methods usually employed for low-frequency, microsecond duration impulses are found inadequate. The author analyzes, using the La Place transform theory, the transient response of two circuits. The differentiating circuit is found impractical. Class C operation of a pentode, having sinusoidal input, with a parallel LC plate circuit can give the desired pulse. For analysis an idealized plate current-grid bias characteristic is used. The transient response of a 6 mc/sec. circuit to a 700 kc/sec. input was measured. Definite values of Gm … Read more
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1950 — The web strength of I beam sections in light alloysAbstract
This investigation deals with the possibility of local failure in 4" aluminum I beams due to insufficient bearing area at end reactions and includes an investigation of the column theory of such failure. A comparison is made between the failure of two types of aluminum alloy, 17-ST and 65-ST. The application and determination of design formulae to determine the width of bearing necessary is explained and demonstrated for the 4” I beam. Read more
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1950 — Unions and wage rates in the newsprint industries of Quebec and Ontario, 1909 to 1948 : a method of assessing the influence of Labour Unions on wage rates as exemplified by the Canadian newsprint industryAbstract
This project is an effort to study the influence of unionization upon the wages of labour, a subject in which the writer has been interested for some time. The importance of this question is one which needs little demonstration. The economic life of the modern world has been characterized, particularly during the present century by the vast growth of organized labour within the productive processes. The unions of to-day can control the supply or labour in given industries and can bargain on terms of equality with management. Read more
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1950 — Specific heats of crystalline solids containing more than one atom per unit cellAbstract
The theory of Specific Heat has two very distinct parts to its development. These are a) the Classical Theory, b) the Quantum Theory. The Quantum theory was first applied by Einstein in 1907 and it was in this paper (1) that Einstein solved the fundamental problem of the subject. Einstein replaced the classical mean energy for a linear oscillator by an expression derived using Planck's hypothesis as to the quantal relationship between energy and frequency. Since the specific heat is defined as being the derivative of the energy with respect to temperature, it was a simple matter, once having an … Read more
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1950 — The reaction of nitrogen atoms with methane and ethaneAbstract
With the exception of the inert gases, the gaseous elements do not exist in the atomic state at ordinary temperatures. They combine with themselves to form stable molecules which will dissociate only at elevated temperatures. However, there are many chemical processes which involve these materials and which indicate that, at some time during the reaction, they exist as atoms. Read more
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1950 — A sociological study of three philanthropic financial campaigns in MontrealAbstract
Although philanthropy is a traditional pattern of activity in our society, its sociological implications, particularly the institutional and money-raising aspects, have not been greatly explored or investigated. It is this type of activity which the sociologist should investigate since, from common sense observation, it is evident that it is a recurrent feature of our urban life requiring the efforts of numerous individuals, fincially and otherwise. Read more
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1950 — Measurement of heat transfer from precipitation particles to the atmosphereAbstract
An original method la devised here and instrumentated for the measurement of heat transfer from precipitation particles (particularly liquid drops) to the atmosphere when the particles are falling at their terminal velocities. The results of the measurements made by this system are compared to what simple theory predicts. A qualitative discussion is made of the reasons for the discrepancy. The shortcomings of the general measurement method are discussed and suggestions are made for extension and improvement of the system. Heat transfer data for various drop sizes at terminal velocity and for an artificial snow-flake are presented. Read more
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1950 — Crystallographic investigations using the shape of the nuclear magnetic resonance lineAbstract
The proton nuclear magnetic resonance was observed in NH4Cl at -195°C. The line shape was interpreted in terms of nuclear spin, nuclear g-factors and lattice parameters of NH4Cl according to the theory of Van Vleck. From these considerations, the N-H distance in NH4Cl was measured as 1.075 ± 0.015 A0. A correction factor for the effect of the modulation field on the line shape has been derived and applied to the results of other experiments of the same type. Read more
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1950 — A theoretical and technical study of autography as a histological method for localization of radioactive elementsAbstract
An "autograph", also known as a "radioautograph", "autoradiography or "historadiograph", is the "signature" left by a radioactive particle in a photographic emulsion, and is, therefore, the visual evidence of the presence of radioactivity in the structure in contact with the photographic emulsion. Radioisotopes present in biological material may be detected in two ways: 1) chemically, using the Geiger counter method and 2) histologically, using the above photographic technique - autography. It is the latter technique, however, that not only reveals the presence of the radioisotope within the specimen but also allows the isotope to be traced to its precise site … Read more
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1950 — Lens measurement of antenna radiation patternsAbstract
The E-plane radiation patterns of two horn radiators have been measured in the laboratory with a metal lens by the same method as that used in optical diffraction pattern measurements. Comparison with patterns measured outdoors by standard methods show little deterioration over the angular interval ± 15 degrees, for horns of aperture 32 cms, lens of aperture 11O cms, at a wavelength of 3.20 cms. It was found that a stepped lens was unsuited for the purpose because of diffraction caused by the steps. Read more
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1950 — Le drame intime de Marcel Proust et la psychologie de l’amour dans À la recherche du temps perduAbstract
La recherche du temps perdu est une quête de l’amour, vaine et navrante poursuite d'un “mirage délicieux" (1) qui se dérobe et se renouvelle sans cesse dans le désert sentimental d'où l'amour est exile. "Illusion" (2) funeste, "la chimère amoureuse" (3) reserve aux malheureux qui s’éprennent d’un fantôme et qui lui sacrifient leur chair, "un exemple frappant du peu qu'est la réalité pour nous." (4) Read more
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1950 — The construction of a Dempster type mass spectrometer: its use in the measurement of the diffusion rates of certain alkali metals in tungstenAbstract
Details concerning the design and performance of a conventional l80° mass spectrometer are given. The operation of a new type of high frequency positive ion source is discussed and its characteristics are compared with two conventional ion sources, the hot filament and electron-impaction source. Observations on the decay of positive ion emission from heated tungsten filaments have been interpreted in terms of a diffusion process. Analysis of these observations has given values for the diffusion constants of potassium and sodium in tungsten. Read more
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1950 — Anti-Entente tendencies in French opinion, 1904-1912.Abstract
The treaty which initiated the Anglo-French Entente was signed April 8, 1904. It assumed the modest appearance of a new colonial accord having as its essential basis the recognition by Great Britain of French interests in Morocco and by France of those of Great Britain in Egypt. The two countries by the ninth article of the convention "agreed to afford one another diplomatic support in order to obtain the execution of clauses of the present Declaration regarding Egypt and Morocco. The British view of the arrangement was that it was concerned with colonial questions in certain specified localities. Read more
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1950 — The post-natal development of the antero-lateral abdominal wallAbstract
If one accepts the hypothesis that in general the development of a new structure in the animal kingdom follows closely upon the demand for a new function, then the original function of a given structure can be determined by tracing it backwards in the animal scale to the point at which it first appears and noting the particular functional demand acting on the organism at that time. It will be seen that his original function need not be retained, but rather may be lost or transferred to some other structure, and the original structure adapted to some other use. Read more
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1950 — Emotional patterns in skin diseaseAbstract
It has been traditionally assumed by most physicians that illnesses of the body are to be treated as such; and that they are not related to the problems of the psychiatrist or the psychologist. In the treatment of skin diseases, it might be reasonable, then, to suppose that one would be concerned solely with salves, ointments, and such specific care of the affected areas. During the past twenty-five years, however, it has become generally recognised, both by physicians and by psychologists, that such an approach to medical problems leaves out of account many factors which it would be profitable to … Read more
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1950 — A study of the selection of University C.O.T.C. candidatesAbstract
The dissertation that follows is the study of a particular area of officer selection for the Canadian Army. This particular area, the University Contingents of the Canadian Officers’ Training Corps (COTC), is and will be, unless Army policy changes considerably, the principal source for obtaining officers required by the various components of the Army in peacetime. The present Army consists of three main parts, (a) the Active Force, the full-time, standing or permanent force, (b) the Reserve Force, a part-time component which is to be the basis of the main field force in the event of general mobilization, and (c) … Read more
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1950 — Russo-Soviet nationalismAbstract
Nationalism, which we will attempt to define later, has been the stimulating force of European power-politics for the last century and a half; it is now in the process of sweeping the vast Asiatic continent, it has an exceedingly solid hold on the Latin republics in South and Central America, it has taken firm roots in the United States, it is being consciously and purposely developed and indoctrinated in Canada, it is not being forgotten in the Soviet Union - in short, it is still a dominant force throughout the world. Nationalism has played an important role in almost every … Read more
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1950 — Preparation and properties of cellulose crotonoate and acetatecrotonoatesAbstract
Within recent years attention has been drawn to cellulosic materials cross linked by primary valence bonds between the macromolecules because such cross linking might impart certain valuable properties to cellulose derivatives. This chemical bonding between the linear high polymer macromolecules, of which cellulose is built, changes a two- into a three-dimensional molecular lattice and causes change in one or more of the following physical properties: temperature at the softening point, tensile strength and the elongation at break, water vapour permeability and moulding characteristics as well as in solubility. Read more
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1950 — The effect of certain mineral nutrients on the yield and quality of tomatoesAbstract
The Tomato - Lycopersicon esculentum -,a member of the Solanaceae family, is one of the most useful and interesting of all horticulture plants. It ranks next to the potato and the sweet potato in total value on this continent. It heads the list among the perishable vegetables as well as ranking first as a canning crop. If "variety is the spice of life” then we owe this crop a great deal for according to Carver (1918) there are 115 ways of preparing it for the table. Read more
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1950 — The dramatic elements in the novels of Jane AustenAbstract
Jane Austen wrote six novels of manners in the late eighteenth and early nineteenth centuries. Each novel is distinguished by an interesting plot, truthful characterization, and natural dialogue. By a skilful combination of these elements she gave her writings a dramatic quality which tempts a reader to consider them as promising material for adaptation to the theatre. In each story a definite pattern may be pointed out in the development of the action. The pattern followed is that of a comedy which follows a natural order of beginning, middle, and end. Read more
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1950 — The effects of radiation on the properties of quarter-wavelength resonant unshielded parallel-wire transmission lines in frequency range 300 Mc/sec. to 1300 Mc/secAbstract
There is at present uncertainty as to whether radiation takes place from the length of a transmission line as well as the terminations, or from the terminations alone. An attempt has been made to determine the answer to this question, for the case of odd quarter wavelength resonant lines. A short historical survey of the different theoretical considerations, and the reasoning behind them, is given as a preamble to the present investigation. The resonant line method of Chipman was used to measure impedance of resonant lines for various resonant lengths and at various frequencies. From this data, the apparent terminating … Read more
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1950 — The effects of an axial pressure gradient on the boundary layerAbstract
A review of the literature on laminar and turbulent boundary layers was made; a resume of this is included. The review and resume cover both theoretical and experimental studies, and was used to indicate the methods employed in expressing the results. The experimental work described in the thesis consisted of a series of tests carried out in a variable pressure wind tunnel. The results of the tests enabled a study of the effects of an adverse pressure gradient on the characteristics of a turbulent boundary layer to be made. The studies confirm salient known effects of an axial pressure gradient … Read more
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1950 — Methods of evaluation the germicidal activity of quaternary ammonium compoundsAbstract
The quaternary ammonium compounds (QAC) are complex organic compounds possessing great surface activity and germicidal properties. At the present time there are hundreds of preparations on the market in the United States and about 100 licensed for sale in Canada which are compounded from or are composed entirely of one of the many QAC available. About 45 per cent of those available in Canada are composed in whole or in part of di-isobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride which, for brevity, will be referred to as Hyamine 1622, the trade name given this substance by the manufacturers, Rohm and Haas of … Read more
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1950 — Experimental studies on complete deprivation of arterial supply to the liver, with special reference to welch bacillus infectionAbstract
It has been known for many years that complete ligation of the arterial supply to the liver was rapidly fatal in several mammalian species. Considerable speculation as to the pathological changes and mechanism of death have failed to uncover a satisfactory explanation. In general, if the portal vein is left intact, arterial ligation alone does not produce definite infarction, but a focal or massive necrosis usually appears within twenty-four hours. In 1949 it was reported by Markowitz, Rappaport and Scott that dogs which were treated with penicillin were able to survive complete hepatic arterial ligation. Read more
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1950 — Studies of the effect of polymerizing temperatures on the nutritive value of herring and linseed oilsAbstract
Diets containing unheated and heat polymerized herring and linseed oils were fed to male white rats. The oils were incorporated in the diets at 20$ (herring and linseed) and 10$ (linseed) levels. Linseed oil, segregated by propanol or with additions of antioxidants were tested. Supplements of sheep feces and dried brewers yeast were fed with linseed oil diets to determine their prophylactic and curative properties. Heat polymerization decreased the nutritive value of the oils as assessed by the growth rates, feed consumption, and the physical condition of the animals. Increasing the heated oil content of the diet from 10 to … Read more
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1950 — Le développement du concept de personnalité juridique et les unions ouvrières au Canada.Abstract
«Travailleurs de tous les pays, unissez-vous! » Cette exhortation pathétique, lancée il y a bientôt un siècle, fut désormais pour la classe ouvrière le but suprême de ses efforts. Cette formule donna naissance au syndicalisme. Les relations du travail ont, dès lors, évolué dans un sens collectif. Progressivement, des relations s’établissent entre employeurs et salariés, dépassant le cadre de relations d’homme à homme. A la notion d’individu, se superpose la notion de groupe. Cette notion, d ‘ ailleurs, n’a pu vraiment s‘établir que du jour où la coalition a été reconnue par les uns et les autres comme un moyen … Read more
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1950 — The effect of oxygen enrichment of the air intake of a diesel engine on the exhaust gas composition and the combustion processesAbstract
Small additions of oxygen to the air intake of a Diesel engine increase the temperature at which the combustion processes occur in the cylinder, and have very pronounced effects on the composition of the exhaust gases. Under no load conditions and at constant speed, the concentration of nitrogen oxides continuously increases with enrichment, while those of aldehydes and carbon monoxide decrease. Similar trends are observed for a medium load at constant speed. The behavior may be explained by the effect of an increased temperature. Beyond a critical oxygen enrichment of the intake, a reaction temperature is eventually reached at which … Read more
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1950 — Reading difficulties as a social work problem: a study of social and emotional factors in reading difficulties, and the role of the social worker in the treatment of reading difficultiesAbstract
Irrespective of the setting within which he works, the social worker is likely to encounter children who are not making progress in school because of difficulties with reading. Such children tend to become "problem children," and to find their way into Child Guidance Clinics and Juvenile Courts. Retardation in reading makes school work progressively more difficult for the child, since, as he advances in grades, his success in all subjects tends to depend more on reading ability. As he experiences failure in his school work, he is apt to lose interest in it and eventually leave school before he has … Read more
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1950 — 3-Hydroxyethyl glucoseAbstract
In a Ph.D. Thesis submitted in 1946 from this Laboratory, Tasker prepared in pure form the series of the monoethyl ethers of the polyethylene glycols, R(OCH2CH2)n0H, where n was 1, 2 or 3. The tendency of several of these compounds to form peroxides when exposed to light and air was noted, the esters made with p-toluenesulfonyl chloride (tosyl chloride) and pyridine were prepared, and the replacement by iodine atoms of the tosyloxy groups in the products was studied. Tasker then applied the tosylation-iodination technique to a commercial hydroxyethyl ether of cellulose, but his results made it clear that side-reactions of … Read more
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1950 — The effect of potassium deficiency on gastric secretionAbstract
Webster, D. (Supervisor) Read more
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1950 — Biology of daphniaAbstract
Swammerdam, the Dutch scientist, was the first author who took notice of any of the Daphniae. In his Historla Insectorum Generalis, 1669, he gave a description of a species of Daphnia, which resembled Daphnia pulex and which he named Pulex arboreus or arborencens. He stated that its beak was slender and pointed, and was used for drawing up food. He called the second antennae arms and described their motion as three-fold—rectilinear, unequal, and gyratory. He asserted that there were two eyes which seemed to be joined together. Merrett mentioned Daphnia in his Pinax rerum Britannicarum, published in 1677. Read more
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1950 — Protamine-heparin titration methods for the determination of circulating anti-coagulantsAbstract
The hemorrhagic syndromes that occurred after atomic bomb irradiation (1) have attracted attention, because the phenomena did not seem to be fully explicable on the basis of thrombocytopenia alone. It was first suggested by Allen and Jacobson (2), that an excess of heparin in the blood might be the cause of the decreased coagulability and bleeding tendency after acute ionizing irradiation. Allen then developed a heparin-protamine titration test (3) tor the demonstration of heparin or heparin-like substances in the circulating blood. Read more
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1950 — The meaning of diabetes mellitus to the patient : with special reference to a group of twenty-five patients at the Royal Victoria Hospital 1942-43Abstract
Diabetes Mellitus is a chronic disease which requires active participation by the patient in order for treatment to be effective. Because of the responsibility which must be placed upon the diabetic and the nature of the symptoms of the disease as well as its complications, it is reasonable to expect that such an illness would create special problems for those who have it. The provision of adequate instruction to permit diabetics to carry out the treatment prescribed is a prime requisite. Some degree of intelligence is necessary to absorb the instruction given. Read more
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1950 — The y-ray induced oxidation of Fr+2 ion in dilute aqueous solutionAbstract
In 1895, Roentgen (1) discovered that invisible rays emanating from an electrical discharge tube produced blackening of a covered photographic plate. In the following year Beoqueral (2) observed a similar phenomenon produced by invisible rays from uranium-containing compounds. These were the first observations of a chemical change produced by ionizing radiations. The discovery of the radioactivity of radium by Mme. Curie (3) in 1898 led to the observation of a multitude of other effects produced by these radiations. For example, it was a matter of great concern that aqueous solutions of radium compounds continuously evolved hydrogen and oxygen. Read more
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1950 — An investigation of the motivational factor involved in academic successAbstract
This investigation is an attempt to obtain a quantitative measure of the motivational factor involved in academic achievement at the university level. Intelligence tests can be used successfully to discriminate between those who would most likely profit from a university education and those who would not, but their ability to predict success within the university group itself, is of a low order. The primary assumption in this piece of research is that prediction at this level involves more factors than intelligence, and that probably the most important among these other factors is motivation. If tests of these two factors were … Read more
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1950 — Demonstration of a ‘steady state’ of thyroidal iodineAbstract
Nowadays it is customary to regard all cells as miniature physical-chemical factories with specializations particular to each tissue or organ. The activity of cells may involve only the synthesis of substances for the upkeep of the cells themselves, or, in addition, the synthesis of substances to be released to the outside. In the latter case, raw materials are taken into the cell, incorporated into some new substance, and then released in this new form into the extra-cellular spaces or to the outside. The activity of such a secreting cell can be subdivided into a number of phases. Those may be … Read more
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1950 — Relation of estimates of the availability of phosphorus to soil treatments and to crop yieldsAbstract
"Phosphorus is so basic to the whole problem of crop production that probably no other subject in the field of soil fertility has received more attention than the phosphorus problem in its various soil-plant and soil-animal relationships and it probably will continue to challenge the best efforts of investigators for many years”. (27). "Phosphorus is the only element which must be purchased and returned to the most common soils of the United States, it is the key to permanent agriculture on these soils". (20). Read more