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The decimal code scale for indicating the growth stages of cereals as developed by the authors and published by Eucarpia is explained and described

The effect of solvent viscosity on DNA renaturation rates has been investigated as a function of temperature for a number of solvent systems. The results are all consistent with a microscopic viscosity limitation of the rate determining step. Rates of renaturation in perchlorate and quaternary ammonium salt solutions are also discussed. Increasing the macroscopic viscosity with dissolved neutral or anionic polymers increases, rather than decreases, renaturation rates due to the excluded volume of the dissolved polymers.

An emission spectrographic determination of fifteen rare earth elements in thorium was developed, the spectrographic procedure was carried out using low current d.c. arc and using Sc as an internal standard. The rare earth impurities were concentrated with cation-exchange resin. Very high sensitivity was achieved with 1 g sample. The detection limits range from 0.01 μg for Yb to 0.5 μg for Pr and Nd.

Forced heterokaryons between auxotrophic strains of Aspergillus niger produce rare (10~4) heterokaryotic conidia which can interfere with the selective recovery of somatic diploid strains which occur with a frequency of approximately 104. Replating of conidia derived from prototrophic colonies which develop on the selective minimal medium results in enrichment for the somatic diploid since virtually all of the diploid conidia can germinate on the selective medium whereas only 10of the conidia derived from heterokaryotic colonies can germinate on the same medium.

DK-4000 Roskilde, Denmark. lack of separation in the magnetically driven shock tubes could be caused by either of these effects, or whether it is due to other phenomena as reported by previous investigators 5

TyHE present paper aims to present observations on hydras during six T Syears' cultivation in the laboratory and to compare them with the observations of others (Parke, I9oo; Grosz, 1925; Hyman, 1928). Surprisingly, tentacle formation and the determination of tentacle number have not been fully investigated previously. New problems attacked have been the formation, addition, and resorption of tentacles and the dependence of tentacle number on size, age, and other factors. Tentacle increase through treatment with chemicals will be reported elsewhere. The species used was designated Hydra oligactis Pallas 1776 in previous publications but is now believed to be an undescribed species.

Ketamine [2-(o-chlorophenyl)-2-(methylamino) cyclohexanone monohydrochloride], a new short-acting anesthetic agent which does not inhibit laryngeal or pharyngeal reflexes, has been studied in 14 pregnant subjects and 18 nonpregnant controls. Approximate clearances calculated indicated a reduced clearance in pregnant subjects (48 cf. 64 ml. per minute per kilogram). Side effects included a 30 to 40 per cent increase in systolic and diastolic blood pressure, an increase in pulse and respiration, salivation, and nausea, and vivid but usually pleasant dreams. The fetal pH did fall after administration of anesthesia, but remained in the normal range along with Pco 2 and Pco 2 . Intrauterine tone increased, and there were changes in fetal heart rate, but none that might not have occurred with advancing labor. Newborn infants were not unduly depressed if the dose was kept below a priming dose of 1.5 mg. per kilogram followed by infusing 0.08 mg. per kilogram per minute. Serum bilirubin concentrations in the newborn infant were slightly increased and could not be accounted for. Mothers and babies all went home at the expected time post partum in apparent good health.

The heterocaryon test was used to confirm the non-nuclear basis for UV sensitivity in a mutant of Neurospora crassa (uvs-2). A model is presented to explain the results from a cross and the heterocaryon test in which the determinants defined by the uvs-2 mutation are postulated as being bound to the nuclear membrane.

The importance of soil aeration to plant development has been recognized since the beginnings of agriculture. As our knowledge of the physiology of roots has grown, the beneficial effects of soil aeration have been assigned to a stimulation of root growth (4) and thus an increase of root area and penetration, and more recently to a direct stimulation of aerobic processes of salt accumulation. Hoagland and his associates particularly have shown that the rate of mineral accumulation in roots containing respirable carbohydrates may be positively correlated with the oxygen supply (8, 24). Although many data upon the toxic effect of carbon dioxide on protoplasm are available, this phase of the soil aeration problem has been generally overlooked. Free (7) and Kramer (16) have shown a reduction of water absorption by roots with increased C02 concentrations. Hoagland and Broyer (9), however, thought the effect of C02 related to its displacement of oxygen, and Arrington and Shive (3) concluded that reduced C02 concentrations were not a factor in the beneficial effects of the aeration of a

Shoot apices of 7-day old foxtail millet(Setaria italica(L) Beauv.) seedlings treated with 2 and 20 mg/L of dimethyltetrachloroterephthalate (DCPA) were examined under the electron microscope. Cell division is interrupted. The nucleus and nucleolus do not disintegrate and chromosomes do not differentiate. Instead, giant nuclei and giant nucleoli occupy most of the cell volume in the meristematic regions. Several nucleolar caps form on the giant nucleolus; and in the advanced stages, they separate and are encircled by a nuclear membrane to form multiple nuclei. Other organelles are also affected. Cristae and thylakoid membranes of mitochondria and chloroplasts degenerate and multiple vacuoles form. Cell walls are markedly more osmophilic after DCPA treatment. Treated cells are less turgid than controls.

Velocity fields of tube extrusion problems through curved dies are presented for an incompressible material. These velocity fields are also applicable to conical and square-cornered dies. Thus, in principle, upper bound solutions for tube extrusion problems through arbitrarily shaped dies are obtained. As an illustration, tube extrusion processes through conical dies of small cone angle have been treated. Effect of die geometry and friction is presented graphically.

The direct reaction model of ion–molecule reactions proposed by Wolfgang to explain the velocity dependence of products of exothermic reactions is refined and extended to yield the angular distribution of products as well. The model consists of consecutive “two‐body” trajectories for reactants and products with “reflection” of radial relative velocities at a reaction radius. It is found that a single value of the reaction radius yields velocity and angular distributions in substantial agreement with experiment for the Ar++D2 reaction over a substantial energy range. Some predictions of the model and some possible modifications are also discussed.

An improved finite difference method is presented. This is exemplified by computing the natural frequency of vibrating plates. A new formulation of the problem showing computational advantages is derived. A procedure for efficient implementation of the improved method is given. Numerical examples are calculated showing results comparable to other methods but employing far fewer unknowns.

The so-called quasiclassical approximations are shown to give, in a certain restricted sense, lower bounds to energy eigenvalues. Variational calculations of the energies of hydrogenlike atoms are carried out as an illustration.

The exponential matrix method of Magnus is applied to the solution of the time‐independent Schrodinger equation for potential scattering. The formal properties of this method as a numerical technique are analyzed and the close connections to the WKBJ approximation are also shown. The use of the Magnus series is shown to yield the correct behavior near the origin without the Langer modification of the WKBJ equation. Applications to the scattering from above a potential barrier and to the phase shifts for a Lennard‐Jones (12–6) potential are given.

Successful growth of Mycobacterium lepraemurium was observed in cultures of mouse peritoneal macrophages. The optimal host cell maintenance medium was composed of 40% horse serum, 50% of the chemically defined medium NCTC 109, and 10% of a 1:5 dilution of beef embryo extract, supplemented with both liver extract and ferric nitrate. Multiplication of the bacilli was observed in 1 week and maximal growth in 6 to 7 weeks. All macrophages were filled with tens to hundreds of the organisms in cultures showing maximal growth. Glycerol caused an increase in the normal length of M. lepraemurium , without a corresponding increase in the number of the bacilli. Elongation of M. lepraemurium was observed 3 or 4 days after infection. Rapid and uniform growth of M. lepraemurium was achieved in serially transferred cultures (subcultures). The cumulative increase of the number of intracellular bacilli was 1.4 × 10 20 -fold in 14 transfers over a period of 68 weeks in one series, and 10 17 -fold in 12 transfers over a period of 56 weeks in another series. The generation time of M. lepraemurium was 7 days, a growth rate which approximates the fastest growth of the organisms in vivo. Organisms harvested from cultures at various stages of growth produced murine leprosy in mice, but showed no growth in bacteriological media. The present model offers an opportunity for studies on the host-parasite relationship without the complication of extracellular growth of the parasites.

By taking the effect of surface tension and viscosity into consideration, Bellman and Pennington [2] have generalized the original treatment of the problem of Taylor instability [1]. They claim, however, that a problem in which the motion starts from rest cannot be treated with their linearized formulation. In this paper, the initial value problem is treated and, although the algebra becomes more complicated, the linearized analysis suffices. In particular, the cut-off wave number as found in [2] is not modified.

The classical averaging procedure of Roberts for the determination of the parameter Cn in the simple distortion potential, V0n(x)  Cn exp(−αx), is examined further. An analogous quantum averaging procedure is also investigated.

All auxotrophs of Aspergillus foetidus and all but two auxotrophs of A. niger which we isolated yield glucoamylase and citric acid, respectively, at levels below that of the prototrophic strain from which they were derived. Results of representative heterokaryon tests suggest that the nucleus was principally responsible for the inheritance of citric acid or glucoamylase production. Most somatic diploid strains of A. foetidus gave rise to higher yields of glucoamylase when compared to their haploid component strains. Both heterokaryons and somatic diploid strains of A. niger synthesized between auxotrophs which were simultaneously reduced in citric acid yields also gave rise to enhanced yields when compared with their haploid components. The yields of a heterokaryon and somatic diploid synthesized between two high producers of citric acid were not higher than those of respective haploid components. We concluded from these results that gene dosage (or ploidy) does not increase the yield of citric acid. The apparent enhancement in yields observed in diploids or heterokaryons synthesized between auxotrophs with reduced yields in both species can be interpreted as resulting from intergenic complementation.

SummaryThe mean cardiac output per minute per square meter of body surface for a group of 10 normal ferrets was found to be 2.476 liters. The average circulation time by the fluorescein technic was 6.8 seconds and 4.5 seconds as determined by the cyanide method. The average mean arterial blood pressure was 147 mm Hg. Various other related data were also tabulated.

The pattern of the electrical response of the visual cortex to the stimulation of optic nerve or lateral geniculate body has been analyzed into three components representing the activity of three conducting pathways composed of three different sized fibers. The three components of the cortical response to geniculate stimulation can be selectively potentiated by continuous illumination of the retina with monochromatic lights. The red light enhances predominately the first component, green the second and blue the third. It is concluded that the nerve impulses for red are probably transmitted mainly by large sized fibers, those for green by medium and large sized fibers and those for blue by small fibers., Chang H. T. IV. - Triple conducting pathway in the visual system and trichromatic vision. In: L'année psychologique. 1949 vol. 50. pp. 135-144.

ConclusionThese observations indicate that a fraction of the PR8 strain of influenza virus possesses the toxic property of lowering arterial blood pressure in rats.

The discrepancy between the measured steady-state speed of the current sheet and the theoretically predicted value is examined through a detailed analytical and experimental study of the basic assumptions used in the model. It is found phenomenologicaly that the observed deviation at dis-charge conditions of low voltage and high pressure could be attributed mainly to the spreading of the current-carrying region in time. The deviation occurring at discharge conditions of high voltage and low pressure could be attributed to the possible presence of an ion drag caused by the interaction between the plasma and the electrode surface.

This investigation was conducted to define the plastic stress distribution at a section 90 degrees from the point of load application on a ring. The elastic and plastic stress distribution was determined experimentally by using postyield strain gages and the stress-strain relationship obtained from a uniaxial tensile test. The experimental results in the elastic range were found to agree with presently available theoretical predictions. A theoretical plasticity analysis of the ring was made by assuming that it deforms to the shape of an ellipse and that plane sections remain plane. The strains determined in this manner were used to calculate stresses off the tensile stress-strain curve. The experimental results indicated that this initial analysis gave a good approximation of the stress distribution for large deflections of the ring.

The effect of wall friction on the current-sheet speed is examined by taking some plausible forms of the friction into consideration. The analysis shows that the current-sheet always attains a steady state regardless of the types of friction concerned. It further shows that the experimentally observed velocity limitation of the current-sheet at discharge conditions of high voltage and low pressure might be attributed to a friction drag varying linearly with the driving current and the current-sheet speed.

A thermodynamic investigation of the U3O8−z phase, mole ratio n(O)/n(U) from 2.60 to 2.67, from 840 to 1450 K via measured partial pressures of O2, p(O2), ranging from 10−6 to 1 atm was obtained by a thermogravimetric gas-equilibration method. Values of the chemical potential of O2 and the standard Gibbs free energy of formation of the U3O8−z phase were calculated for various compositions and temperatures. The nature of the defect structure of the sub-stoichiometric U3O8 at low temperature and/or high p(O2) appears to be randomly distributed doubly charged oxygen vacancies. However, at high temperature and/or low p(O2), i.e. greater departure from stoichiometry, a more complex defect structure appears to occur. The z-dependence of the standard Gibbs free energy of formation of solid U3O8−z was calculated, and hence, a more accurate evaluation of the standard Gibbs free energy of formation of the gaseous UO3 was made via the reaction: ( 1 / 3 ) U 3 O 8 − z ( s ) + { ( 1 + z ) / 6 } O 2 ( g ) = U O 3 ( g ) .

The high and low resolution mass spectra of the N-acetyl-N,O-methyl and N-acetyl-O-trimethylsilyl derivatives of kanamycin A have been determined and interpreted, along with those of deuterated analogs under conditions of electron impact. In addition, the chemical ionization mass spectrum of the N-acetyl-N,O-methyl derivative is presented. The use of these spectra for recognizing structural features, such as the sequence of the sugar units, is discussed. The characteristics of the two types of derivatives are compared. The value of the chemical ionization spectrum and the complementary nature of the data obtained from it are emphasized.

The effect of streptomycin on the growth of an obligate intracellular bacterium was studied in a new host-parasite cell system. The system consisted of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages. Since these organisms do not grow in bacteriological media, the influence of extracellular bacterial growth can be ruled out. The suppressive activity of streptomycin was observed in a total of five experiments. At the end of 4 weeks, the average number of organisms per macrophage for the controls was 65.7; for cultures with streptomycin at concentrations of 0.5, 1, 5, 10, 50, and 100 μg/ml of medium, it was 45.4, 38.3, 28.7, 22.7, 13.4, and 8.2, respectively. A good dose-response relationship was evident. M. lepraemurium which had been treated in macrophage cultures with various concentrations of the antibiotic for 6 to 8 weeks was used to infect fresh macrophages. These cultures were in turn treated with streptomycin. Resistance of the organisms to streptomycin did not occur.

Many materials were surveyed with the hope of finding a material which could be used in room temperature simulations of forming processes on hot steel—particularly the process of the rotary piercing of tubes. By comparing the results of simulations on a model mill with the results of an actual production process, it was found that a composition of 81.0 percent (by weight) Plasticine clay, 16.2 percent kaolin, and 2.8 percent paraffin proved to be an excellent, if not optimum, analog material when used at 55 deg F. As a result of strength data collected in this investigation it is expected that this composition-temperature combination might also be used for the simulation of the plastic deformation of steel at room temperature.

The instability of the accelerated interface between a liquid (methanol or carbon tetrachloride) and air has been investigated experimentally for approximate sinusoidal disturbances of wave-number range from well below to well above the cut-off. The growth rates are measured and compared with theoretical results. A third-order theory shows the phenomena of overstability which is found in the experimental results. Some measurements of later stages of growth agree moderately well with the available theory and disclose some additional phenomena of bubble competition, Helmholtz instability with transition to turbulence, and jet instability with production of drops.