Tentative Theory Research Articles

The Catalytic Action of Organic Peroxides on the Polymerization of Ethenoid Compounds. III. The Effects of α-and β-Naphthoyl Peroxide on the Polymerization of Styrene

Abstract (1) The rates of polymerization of styrene with α-and β-naphthoyl peroxide have been found to be in a parallel relation with the rates of decomposition of the peroxides at 35° and 60°C. (2) Aromatic amines such as dimethyl aniline and ethyl-benzyl aniline, and urotropine accelerate the decomposition of the peroxides. (3) In the experiments using α-peroxide, the presence of the aromatic amines and urotropine show a retarding influence on the rate of the polymerization. In the experiments using β-peroxide, on the contrary, dimethyl aniline and ethyl-benzyl aniline influence the peroxide to accelerate the polymerization. (4) Heterocyclic amines such as pyridine and quinoline manifest practically no influence either on the rate of decomposition of the peroxides or on that of the peroxide catalyzed polymerization of styrene. (5) In respect to the action of amines, a tentative theory has been made.

The Catalytic Action of Organic Peroxides on the Polymerization of Ethenoid Compounds. I. The Activity of Substituted Benzoyl Peroxides in the Polymerization of Styrene

Abstract (1) The rates of polymerization of styrene with m- and p-substituted benzoyl peroxides have been found to be inversely proportional to the square root of the dissociation constants of the corresponding substituted benzoic acids. (2) The thermal decomposition of the peroxides in styrene has been observed to be of first order in all cases. (3) It has been found that the rate of decomposition of peroxides is in a parallel relation with the rate of polymerization of styrene. (4) The relation between the amounts of radicals derived from the peroxides and the rates of polymerization has been studied. (5) In respect to the small activity of dinitro-benzoyl peroxides, a tentative theory has been made.

Observations on a transmissible agent determining sexual differentiation in Bacterium coli

SUMMARY: Analysis of a pair of Bacterium coli K-12 mutants which had ceased to show genetic recombination after storage, implicated mutant 58–161, which had previously behaved as a gene donor strain, as the infertile parent. Infertile 58–161 failed to display recombination when crossed with a gene acceptor strain (W-677) but was able to mate successfully with wild-type K-12 and prototrophic recombinant donor strains, i.e. it had become a gene acceptor. The terms ‘F + ’ and ‘F − ’ have been adopted (after Lederberg, Cavalli & Lederberg, 1952) to denote donor and acceptor strains respectively. Growth of either 58–161/F − or W-677/F − in mixed broth culture with 58–161/F + resulted in the conversion to F + of up to 75 % of re-isolated colonies of the initially F − strain. F − strains converted to F + by strains of dissimilar genotype showed no phenotypic alteration and, therefore, were not recombinants. Washed, mixed cultures on minimal agar yielded an F + conversion rate of only 3·6%, while 100 % recombinants were F + under the same conditions. The F + agent could be transmitted serially through F − strains and was not filterable. While F − × F − crosses were sterile, F + × F − crosses showed maximum fertility. F + × F + crosses were c. 1020 times less productive than F + × F −. The F + agent had a determining effect on the phenotype of recombinants. Thus, when the F + F − relationship was reversed in F + × F − crosses between the same pair of mutants, almost all recombinants which did not show new patterns of unselected marker characters had the phenotype of the F − parent. Among recombinants from F + × F + crosses, the phenotypes of both parents were represented though not always equally. This effect of F + on the phenotype of segregants invalidates much of the evidence for genetic linkage in K-12. Reversal of F + potential in otherwise similar crosses also had a marked effect on the efficiency of prototroph formation on minimal agar supplemented with various growth factors required by one of the parent auxotrophs. A tentative theory of the mechanism of recombination is presented on the basis of this and previous work. This supposes that F + is a non-lytic infectious agent, harboured by F + cells and absent from F − cells, which becomes effectively associated with a part (or parts) of the chromosomes of a small proportion of the cells it inhabits. The F + agent thus acts as a gene carrier in the transfer of genetic material from F + to F − cells.

An examination of some site and transmission-path errors of the Decca Navigator system when used over land

The errors in phase-difference measurement which arise when using the Decca Navigator system, operating at frequencies near 100 kc/s, in the immediate neighbourhood of obstacles such as trees and telegraph wires, have been examined; the results of the measurements are described and discussed. Vertical obstacles show some uniformity of behaviour, but long horizontal conductors produce widely varying effects. A tentative theory of the phase errors due to a single tree is given in an Appendix, and fairly good agreement with observations is obtained.In Section 2 of the paper, errors obtained at good sites on the base line extensions of the red and green lattices are shown graphically. The effects of the near-field components and of the finite conductivity of the ground are apparent. Good agreement is obtained between the mean of the observations and a composite theoretical curve, based on the use of Norton's plane-earth theory and Bremmer's curved-earth theory of ground-wave propagation. Rapid fluctuations of error about the mean curve are observed, indicating that the phase velocity of the ground wave may show variations from point to point of up to 1% of the mean value.

Enuresis; a brief review; a tentative theory and a suggested treatment.

Enuresis; a brief review; a tentative theory and a suggested treatment.

Electrical Noise from Instrument Cables Subjected to Shock and Vibration

Existing information on the reduction of spurious signals from instrument cables is reviewed. A tentative theory is formulated to account for the known data. Subsequent experiments confirm this theory and allow the formulation of a detailed mechanism of noise generation in cables. The noise may be eliminated for practical purposes (reduced by a factor of 500 or more in some cases) by having continuous electrical conduction between both surfaces of the insulating dielectric and the adjacent conductors. A simple procedure is outlined to make short lengths of this cable for laboratory use, and an industrially applicable method is suggested. There appears to be no limit on how small the diameter of such cables could be made.

Les ondes atmosphériques considérées comme associées aux discontinuités du tourbillon

It is suggested that the jet stream at about 12 km-level may be idealized as a system of two or three zonal currents with uniform but different values of absolute vertical vorticity ζ, and such that the wind velocity itself is continuous at each boundary. The approximation of a horizontal non-divergent motion is made for the jet-stream's waves (chapter II), and a proper system of equations is derived for these waves (by using the meridional coordinate γ defined by tanh γ = sin ? (? = latitude), the equations are particularly simple even when the earth's curvature is taken into account, and in the case of constant ζ the problem is reduced to the resolution of the very classical equation ?2 ? = o, where ? is the local disturbance of the stream function. The case of a simple jet (two currents), then that of a double jet (three currents) are successively considered in the next chapter, the wave motion being assumed to vanish at each pole, and it is also shown how some of the results can be generalized for a larger number of currents. (In any case the dispersion equation, giving the angular phase-velocity α in terms of the angular wave-length λ (inverse of the wave number, which must be an integer), is an algebraic one in α, and its degree equals the number of internal boundaries.) The waves of a simple jet are therefore all stable (their dispersion equation is α = ω0 – σ0λ, if ω0 is the angular wind-velocity at the axis, and 2σ0 denotes the ζ-discontinuity, positive northwards). On the contrary, a system of more than two currents may have unstable (amplified) waves, if one discontinuity 2σ0 is negative while the other ones are all positive. If in addition σ0 is small, the wave lengths of the unstable waves form a definite series of spectral lines, the maximum number of which equals the number of the positive discontinuities, and the phase velocity of these waves is approximately the wind velocity at the latitude of the negative discontinuity: in the special case of a double jet, there is therefore at most one unstable wave length λ0, given by λ0 = (ω1–ω0)/σ1, where the subscripts 0 and 1 are relative to the negative and positive discontinuity, respectively. For all the waves of a simple or double jet, there is a maximum of the amplitude at a definite latitude and the wave motion becomes negligible at a distance of the order of the wave length. The effect of horizontal eddy-viscosity is discussed in chapter IV. If the kinematical coefficient is of the order of 106 C. G. S. at most, it is found that the wave motion is generally modified only in the vicinity of the boundaries. The conclusions are however different in the special case where one discontinuity is very small: some of the stable waves are then changed to damped waves, while the unstable waves are practically unmodified. The problem involves Bessel functions of order 1/3.

Magnetic Susceptibility of Manganese Selenide

The susceptibility-temperature relation for the antiferromagnetic compound MnSe was measured over a range of temperatures between 70\ifmmode^\circ\else\textdegree\fi{}C and -196\ifmmode^\circ\else\textdegree\fi{}C. Evidence was found of a large thermal hysteresis and a dependence of susceptibility on field strength. A tentative theory is advanced to explain the thermal hysteresis in terms of three phases which possess different susceptibilities.

Fluid Film Lubrication of Parallel Thrust Surfaces

During the course of an investigation into the general characteristics of various types of thrust bearing, it has been shown that opposed parallel surfaces, under certain conditions of operation, have a load carrying capacity approaching that of tilting pad bearings of the Michell type and of the same bearing area. Considerable evidence has been obtained, such as the low friction losses, the dependence of coefficient of friction on viscosity, speed and load, and the apparent absence of metallic contact, which strongly indicates that these bearings operate under fluid film conditions. Their performance does not seem to depend on a rounded inlet edge, and the apparent establishment of fluid film conditions without the usually accepted requirement of convergence of the bearing surfaces is regarded as a new phenomenon in lubrication. A tentative theory on broad lines is suggested as an explanation of the behaviour.

STUDIES ON THE ANTIBACTERIAL ACTION OF THE SULFONAMIDE DRUGS

1. In cultures of Staphylococus aureus in a synthetic medium nicotinamide and cozymase were shown to block the bacteriostatic action of chemically unrelated sulfonamide drugs as well as the chemically related compound sulfapyridine. The antibacterial properties of organic dyes totally unrelated to the sulfonamide compounds (methylene blue and thionine) were also nullified by the addition of cozymase to the culture medium. 2. The antagonistic action of the pyridine-containing coenzyme, cozymase, was found, by quantitative study, to be no greater against sulfapyridine than against other structurally dissimilar sulfonamide compounds. 3. The antidrug effects of nicotinamide and cozymase in staphylococcus cultures were observed to be directly proportional to their ability to stimulate the growth of the organism in the synthetic medium. When tested in cultures of B. coli in which they failed to accelerate bacterial growth, these same substances failed to influence the bacteriostatic action of the sulfonamide drugs. 4. The in vitro action of the coenzyme, cocarboxylase, as measured in the Warburg respirometer, was shown to be unaffected by the chemically related drug, sulfathiazole, even when the latter was present in great excess. The above observations fail to support the theory that sulfapyridine, sulfathiazole, and sulfadiazine prevent bacterial growth by interfering with the functioning of the chemically related coenzymes, cozymase, and cocarboxylase. The mode of action of sulfanilamide and its more common derivatives is discussed in the light of these observations, and a tentative theory is offered to explain the differences in bacteriostatic potency exhibited by the various sulfonamide compounds.

Photosynthesis with Radioactive Carbon. IV. Molecular Weight of the Intermediate Products and a Tentative Theory of Photosynthesis

Photosynthesis with Radioactive Carbon. IV. Molecular Weight of the Intermediate Products and a Tentative Theory of Photosynthesis

A Tentative Theory of the Origin of Cosmic Rays

A Tentative Theory of the Origin of Cosmic Rays

TEMPERATURE CHANGES IN THE CORTEX AND HYPOTHALAMUS DURING SLEEP

ArticlesTEMPERATURE CHANGES IN THE CORTEX AND HYPOTHALAMUS DURING SLEEPH. M. SerotaH. M. SerotaPublished Online:01 Jan 1939https://doi.org/10.1152/jn.1939.2.1.42MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByBrain temperature and its role in physiology and pathophysiology: Lessons from 20 years of thermorecording3 December 2019 | Temperature, Vol. 6, No. 4Brain temperature: from physiology and pharmacology to neuropathologyBrain temperature and its fundamental properties: a review for clinical neuroscientists8 October 2014 | Frontiers in Neuroscience, Vol. 8Physiological Fluctuations in Brain Temperature as a Factor Affecting Electrochemical Evaluations of Extracellular Glutamate and Glucose in Behavioral Experiments14 March 2013 | ACS Chemical Neuroscience, Vol. 4, No. 5Brain temperature fluctuations during physiological and pathological conditions12 April 2007 | European Journal of Applied Physiology, Vol. 101, No. 1Physiological and pathological brain hyperthermiaBrain hyperthermia as physiological and pathological phenomenaBrain Research Reviews, Vol. 50, No. 1Fluctuations in neural activity during cocaine self-administration: clues provided by brain thermorecordingNeuroscience, Vol. 116, No. 2Functional imaging of the brain by infrared radiation (thermoencephaloscopy)Progress in Neurobiology, Vol. 56, No. 3Brain metabolism and blood flow during sleepJournal of Sleep Research, Vol. 1, No. 1Preservation of brain temperature during ischemia in rats.Stroke, Vol. 21, No. 5Epidural temperature and possible intracerebral temperature gradients in man6 July 2009 | British Journal of Neurosurgery, Vol. 4, No. 1Effect of 2450 MHz microwave energy on the blood-brain barrier to hydrophilic molecules. D. Brain temperature and blood-brain barrier permeability to hydrophilic tracersBrain Research Reviews, Vol. 7, No. 2Brain, blood and rectal temperature during whole body coolingComparative Biochemistry and Physiology Part A: Physiology, Vol. 79, No. 4Temperature Regulation during Sleep: A Study in HomeostasisAbsence of thermoregulatory vasomotor responses during fast wave sleep in catsElectroencephalography and Clinical Neurophysiology, Vol. 42, No. 3Respiratory frequency as a function of preoptic temperature during sleepBrain Research, Vol. 111, No. 2Gehirntemperatur als Maß der Erregung bei Hühnern26 April 2010 | Zeitschrift für Tierpsychologie, Vol. 35, No. 2Sommeil et température cérébrale du rat au cours de l'exposition chronique en ambiance chaudeBrain Research, Vol. 55, No. 1Origin of temperature changes evoked in the brain by sensory stimulationExperimental Neurology, Vol. 38, No. 3Brain temperature as related to gross motor activity in the unanesthetized chickenPhysiology & Behavior, Vol. 10, No. 3Central Thermoreceptors and ThermoregulationA comparative study of the role of the cerebral arterial blood in the regulation of brain temperature in five mammalsBrain Research, Vol. 16, No. 2Homeostatic mechanisms in the hypothalamusBrain Research, Vol. 13, No. 3Gehirntemperaturen bei HühnernPflüger's Archiv für die gesamte Physiologie des Menschen und der Tiere, Vol. 301, No. 2Brain temperature regulation during sleep and arousal in the dogExperimental Neurology, Vol. 21, No. 2Intracranial heat exchange and regulation of brain temperature in sheepLife Sciences, Vol. 7, No. 7Carotid Rete and Brain Temperature of CatNature, Vol. 216, No. 5111Autonomic Basis for the Rise in Brain Temperature during Paradoxical SleepScience, Vol. 157, No. 3796Temperature changes in the rabbit brain during paradoxical sleepElectroencephalography and Clinical Neurophysiology, Vol. 21, No. 5Local temperature, blood flow, and electrical activity correlations in the posterior hypothalamus of the catExperimental Neurology, Vol. 16, No. 2Brain temperature and brain blood flow in unanesthetized ratsLife Sciences, Vol. 4, No. 24Biochemical changes during sleepZur Registrierung der lokalen Gehirndurchblutung mit W�rmeleitsondenPfl�gers Archiv f�r die Gesamte Physiologie des Menschen und der Tiere, Vol. 284, No. 3Acute Effects of Ataractic Drugs on Spontaneous Autonomic and Metabolic Oscillating Systems in Schizophrenic and Other Psychiatric Patients26 April 2017 | Canadian Psychiatric Association Journal, Vol. 7, No. 2Vegetatives SystemGehirn und vegetatives NervensystemKörpertemperatur und vegetatives NervensystemPhysiologie, pathologische Physiologie und vegetatives NervensystemPsychiatrie, Psychologie und vegetatives NervensystemZwischenhirn und vegetatives NervensystemEnuresis: A Brief Review, a Tentative Theory and a Suggested TreatmentArchives of Disease in Childhood, Vol. 27, No. 135Effect of Hypothalamic Cooling on Cutaneous Blood Flow in the Unanesthetized DogActa Physiologica Scandinavica, Vol. 21, No. 2-3Hirnelektrische Befunde bei gestuften aktiven HypnoseübungenArchiv für Psychiatrie und Nervenkrankheiten, Vol. 181-181, No. 3-4Hirnelektrische Befunde bei gestuften aktiven HypnoseübungenPhysiological Psychology8 February 2018 | Journal of Mental Science, Vol. 90, No. 378 More from this issue > Volume 2Issue 1January 1939Pages 42-47 https://doi.org/10.1152/jn.1939.2.1.42History Published online 1 January 1939 Published in print 1 January 1939 Metrics

Clean-Up and Pressure Effects in Low Pressure Mercury Vapor Discharges: A Reversible Electrical Clean-Up of Mercury

Studies with the ionization gauge reveal that in a positive column discharge in Hg vapor at low pressure there occurs a type of reversible electrical clean-up in which, under equilibrium conditions, a large and continuous exchange of Hg takes place between the space and the walls. The amount of Hg held temporarily in this way on the walls may be several times that in the gas phase. Thus if the current is suddenly stopped, the pressure may rise momentarily to several times its normal value; while if it is suddenly raised from a low value to a high one the lowering of the pressure may be so extreme as to cause surges across the arc or extinction of the arc (common occurrences during the starting of the Cooper Hewitt lamp). Evaporation from and condensation on free Hg surfaces, if these are at all limited in extent, are not rapid enough to prevent the effects. Electrophoretic and pressure effects are shown to be of great importance in these experiments. Thus in equilibrium, in a 2.1 cm tube, 1 m long, the pressure at the anode end was double that at the cathode end when the current was 2 amp. (mean pressure about 1 micron). This result is shown to be sufficiently accounted for by Langmuir's theory of the positive pressure effect. A method for calculating the drift speeds of ions and of the neutral gas in special cases is described. In the present case, a considerable drift of neutral gas is shown to take place under electron impacts towards the anode which compensates for the motion of the ions in the field. The initiation (due to clean-up) and phenomena of isolated surge regions in long tubes are discussed. These regions of aggravated low pressure which are usually situated toward the anode end of the tube, are plainly distinguishable by their relatively weak and reddish luminosity. Also the surges are evidenced by a sharp hissing noise which emanates mainly from the inductance. On suddenly stopping an arc in a tube at 185°C, the Hg which came off the wall spontaneously afterward appeared to have a mean life (τ) on the wall of about 4 min. τ did not appear to vary rapidly with the wall temperature nor did the amount of Hg (Q) so coming off. Q did not vary nearly as rapidly as the positive ion current to the walls. Assuming the clean-up to be due to these ions striking the walls, this and other more direct evidence indicate that Hg is dislodged by ions striking the walls as well as cleaned up thereby and that it is largely the balance between these two effects which determines the equilibrium amount of Hg held reversibly on the wall. The reversible clean-up here described is probably of considerable importance in all practical low pressure Hg discharge devices wherein rapid changes of current occur. In addition to this so-called reversible part of the clean-up, a much larger amount of cleaned up Hg was found which could only be recovered by heating. If the heating were carried out in stages, a quantity of Hg came off with each rise in temperature in such a way as to suggest that the Hg is held with varying degrees of binding. A clean-up on an iron surface was found similar to that on a glass or quartz surface. A tube containing unsaturated Hg vapor when strongly irradiated with the Hg resonance lines failed to show any clean-up from which it is inferred that the clean-up here described is not due to excited or metastable atoms. Careful tests with a McLeod gauge showed that gases other than Hg were not appreciably involved in the present experiments. The observations can be sufficiently accounted for on the tentative theory that ions penetrate into the walls to varying distances or to positions of varying stability, by virtue of their relatively high energies (15 volts or more), where they are held for greater or shorter lengths of time, according to their effective degrees of binding, until they escape as a result of random heat motions occurring either at the original wall temperature or at temperatures artificially elevated either in the oven or locally by ion bombardment.

Tentative Theory of Novae

Tentative Theory of Novae

Origin of the Cochlear Effect

IN 1934 Hallpike and Rawdon-Smith advanced a tentative theory to account for the production of synchronous potential waves within the mammalian cochlea, in response to auditory stimuli1. According to this, the potential waves were held to be set up by movements of a membrane, thought to be polarized, and bounded on either side by the cochlear fluids. It has now proved possible to show that a membrane, polarized in such a fashion, will in fact yield potential waves of the required type.

A Note on Psychopathology and Periodicity

The following tentative theory is to a large extent influenced by Rouart's work. This psychiatrist recognizes two fundamental forms of behaviour—periodic and intermittent.

The Bakerian lecture - The anomalous specific heats of crystals, with special reference to the contribution of molecular rotations

The primary purpose of this lecture is to describe a tentative theory, which I have recently tried to improve, of the contribution that molecular rotations may make to the specific heats and in general to the equilibrium properties of crystals. The occasion of the Bakerian lecture, however, seems a fitting one for a general survey rather than for the detailed exposition of a particular theory, which at best is still far from a final state. I shall spend most of my time therefore in such a general survey of the theory of the specific heats of crystalline solids. Strictly speaking, the theory is not so much a theory of the specific heat as a theoretical construction of the free-energy function of the solid in terms of an assumed model for the atoms or molecules constituting its crystal lattice. From this free energy, the total energy content, specific heat, equation of state and other related equilibrium properties of the solid can of course be deduced by differentiation, and specific heats provide the most striking property easily submitted to comparison with experiment. When we set out to construct theoretical free-energy functions in this way, using the methods of statistical mechanics, the function that we actually construct is the partition function, the quantum mechanical generalization of Gibb’s phase integral ∫ e -E/ k T d Ω over the phase space of solid or other system. The free energy is merely - k T log (partition function). My first object is therefore to describe the present state of the theory of the partition functions of solids and their success or failure in describing the observed facts. This will lead us on naturally to the discussion of various types of anomaly in the specific heat curves not provided for by the simpler versions of the theory, and so to a description of attempts that have been made to explain them, among which the theory of molecular rotations in solids finds its natural place.

STUDIES ON THE ELIMINATION OF DYES IN THE GASTRIC AND PANCREATIC SECRETIONS, AND INFERENCES THEREFROM CONCERNING THE MECHANISMS OF SECRETION OF ACID AND BASE

1. All dyes appearing in gastric juice after intravenous injection in the dog are characterized by having their chromogen in the electropositive ion under suitable conditions. 2. All dyes eliminated in pancreatic juice ionize with the chromogen electronegative under proper circumstances. 3. The amphoteric characteristics of certain dyestuffs, as well as the changes in charge associated with reversible reduction in others, have been taken into consideration, and the lack of success of previous investigators in finding a common characteristic of dyes secreted by the gastric glands differentiating them from those secreted by the pancreas, has been shown to have been due to failure to take these potentialities of the dyestuffs into account. 4. Several possible hypotheses concerning the mechanism of selectivity to dyestuffs have been considered. Differences in distribution in acid, neutral, and alkaline phases will not account for selective secretion without postulating also specific membrane permeability. It is pointed out that the theory most thoroughly in accord with all the facts observed is based upon the pore concept. To restrain electronegative dyes by polar adsorption, the pores of the membranes of the gastric glands would have to be positively charged. Such pores would constitute an electrostatic filter, restraining from passage all mobile ions of the same charge. The anions, which in plasma are mostly chloride, could pass this barrier into the secretion. In order to have hydrochloric acid formation, anion exchange would have to occur, bicarbonate, lactate, or some other anion from the gland lumen returning to balance chloride entering, leaving the hydrogen ion from the weaker acid in the secretion. This tentative theory can also be seen to fit many of the facts of pancreatic secretion, where electropositive dyes are restrained, and alkali is secreted.

LXII.Lattice distortion in nitrided steels and theory of hardness

Summary An X-ray investigation has been made of the changes brought about in the case-hardening of steels by the nitriding process. It is shown that the method produces a surface layer of nitrides and a case of steel characterized by an abnormally diffused and weakened spectrum. Extreme hardness values are associated with this type of spectrum. The interpretation of the X-ray results require the postulation of a distorted atomic lattice and a disturbance of the electron distribution. On the basis of the latter effect a tentative theory of hardness is developed.