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Radiation - Induced Mammary Gland Neoplasia in the Rat: In discussing this subject, data on radiation induced mammary gland neoplasia in the rat indicating that direct interaction between the radiation and target tissue is necessary for maximum neoplasia induction will be presented mainly. Other types of radiation induced neoplasia, in which little or no information on the mechanisms involved is available, will be discussed briefly. In particular, investigations on radiation induced mouse lymphoma will be reviewed, in which neoplasia appears to be an abscopal effect. Implications of these data will be discussed, particularly with regard to possible mechanisms involved, and extrapolation to man.
The Radiation Processing Research and Development Program at Brookhaven National Laboratory: The generic term "chemonuclear" has been assigned to any chemical process system using nuclear energy as the prime energy source. The type of effect which induces the chemical change, or produces the chemical is of importance in classifying the type of chemonuclear process, or reactor involved. Four types of effects are identified for this classification. These are radiation, thermal, electrical, and photolytic effects. The radiation effects include the interaction with matter of high energy particles, or photons carrying energy in the range of a million electron volts (MEV) or higher, and causing primarily ionization effects. Thermal effects include transfer of thermal energy to matter and usually is directed towards producing a thermodynamic equilibrium in the system. Electrical effects are concerned with interaction with matter of particles carrying energy in the range of electron volts up to thousands of electron volts (EV to KEV). The photolytic effects utilize photon energy in the range of infrared through the visible to the ultraviolet radiation (IR, Visible, and UV). As is evident, this classification is somewhat arbitrary since it is primarily based on a division of the energy spectrum which is in reality continuous. It does, however, separate the more conventional methods of inducing chemical reactions from the less conventional, and demonstrates the various techniques in the utilization of nuclear energy. All these techniques must be compared when selecting an economically competitive process.
The Radiolysis and Pyrolysis of Several Polyaromatic Compounds: The radiolysis of several polyaromatic compounds which might be used as coolant material in a reactor was investigated using both gamma and reactor radiation. The compounds selected were naphthalene, anthracene, naphthacene, pyrene, phenanthrene, 1, 2 benzanthracene, chrysene, triphenylene, 9, 10 dihydrophenanthrene, phenazine, 7, 8, benzoquinoline and m-phenanthroline, in addition to the uncondensed ring compounds, biphenyl, ortho, meta and para terphenyl and bibenzyl. Gas yields, percentage decomposition, percentage "high boiler" and number average molecular weights were determined. A correlation was found between radiation stability and electron affinity and singlet triplet excitation energies. The most stable compounds were the condensed ring compounds, naphthalene, pyrene, chrysene, phenanthrene and triphenylene.
Rare Gas Isotope Contents in Mineral Fractions of the Indarch Meteorite: We have measured the rare gas isotopes in mineral concentrates of the Indarch meteorite. We obtained samples from C. Frondel, who crushed some of the meteorite into small particles mainly in the 44 to 88 micron size. He fractionated the minerals into groups according to specific gravity, using heavy liquids and magnetic techniques. The fraction with specific gravity less than 2.4 is approximately 95% tridymite and represents about 1% of the whole stone. The fraction with specific gravity between 2.4 and 2.8 contains calcium sulfide, calcium phosphate, two unidentified minerals, and tridymite and enstatite impurities. This fraction represents a few percent of the meteorite. The fraction with specific gravity between 2.8 and 3.3 consists largely of clinoenstatite and represents about 75% of the meteorite. The troilite is concentrated in the fraction with specific gravity greater than 3.3, and kamacite is concentrated in the magnetic fraction.
RBE of Monoenergetic Fast Neutrons: Cytogenetic Effects in Maize: Investigations on the relative biological effectiveness (RBE) of densely ionizing radiations (with high LET, rate of linear energy transfer) are of importance in both fundamental and applied radiobiology. In the latter, they serve as a basis in setting permissible exposure levels for types of radiation about which little long range experience is available. Some of the best RBE studies have been done on chromosomal aberrations. The difficulty is determining RBE on the basis of chromosomal exchanges or 2-break aberrations is that the dose-response curves differ for radiations of different LET and dose rate. The dose-squared term tends to predominate with radiations of low LET (such as γ rays and most X rays) and high doses or dose rates; the linear term dominates with high LET tracks in general and at low doses or dose rates. The shape of the curves is thought to reflect the existence of two classes of mechanisms by which chromosome exchanges are produced; exchanges caused by the passage of a single ionizing particle account for the linear component of the dose-response curve, exchanges due to the interaction of effects of two independent ionizing particles are responsible for the dose-squared component. This model has been amply confirmed by time-dose studies. The differences in shape of the dose-response curves indicate thus that with densely ionizing radiations, single particle events dominate the radiation response, while with sparsely ionizing radiations, events based on interaction of two or more particles play the leading role; hence the relative effectiveness of the kinds of radiations can not be the same for the two classes of mechanisms. Now the usual method of assessing RBE is based on comparing the doses which produce matching responses, i.e. equal amounts of effect, but at every response level both single action and interaction mechanisms contribute to the total …
A Re-Analysis of Short-Range Order in Cu3Au: Cowley's measurements of the short-range order parameters, αi, in Cu3Au at T=405°C have been re-evaluated taking into account the effects of thermal vibrations and static displacements due to differing atomic sizes. The separate corrections for the thermal vibrations and the first-neighbor atomic size factor are found to be quite large, demonstrating their importance in the usual experiments. When combined, the corrections in this case largely cancel, and only the values of α1 and α3 are appreciably changed. The corrected values are: α1= -.113, α2= +.185, α3= -.009, α4= +.082, α5= -.058.
The Rearrangement of Diphenyl: We wish to report unequivocal evidence for the water promoted, aluminum chloride induced intramolecular rearrangement of the benzene rings in diphenyl. When diphenyl 1→1,1'-C14, prepared in 80% yield via an Ullmann reaction on iodobenzene-1-C1 14, was heated to 100° for 30 min. with 10 mole % of aluminum chloride and 1 mole % of water, the radioactivity, originally localized at the two connecting carbons had been randomly distributed. Recovered active diphenyl was also shown to be randomized when the reaction was carried out for 12 hrs. in a refluxing benzene solution. The degradation method used is outlined in Fig. 1. The view that the reaction in intramolecular is supported by the following facts: (1) The inactive benzene used in the solvent experiments was devoid of activity at the end of a run within the precision of our assay methods. A rearrangement carried out with inactive diphenyl in benzene-1-C- 14 yielded diphenul having an activity indicating less than 0.001% intermolecularity.
Recent Studies on the Experimental Program Requirements for a Super High Energy Accelerator: Brookhaven has sponsored a summer program to study possible experimentation with super-high-energy accelerators of ~ 1000 BeV and to examine the feasibility of colliding beam experiments. A group of about fifty physicists took part in this study program. These investigations are a continuation and supplementary to our previous studies at Brookhaven about two years ago.
Recovery of U from Pyrolytic Carbon-Coated UC2 Spheroids: 100% recovery of uranium from pyrolytic carbon-coated spheroids of uranium dicarbide has been accomplished by an aqueous electrolytic process at the small scale laboratory level. This result was obtained in a system which circulated 1 molar nitric acid through a thin bed of the spheres. The bed was supported between a glass frit and the anode, with which the bed was in contact. The anode was a spiral of platinum wire; the cathode was a grid of titanium wire. Current density was about 0.2 amp/cm2 based on geometric surface area calculated from the average particle size of 150 microns. Initial flow rate was about 1.3 ml/cm2/sec. Reaction temperature was 72-82°C; time was 15 hours. At 1/5 the above current density and at the same temperature recovery was smaller and was independent of concentration of nitric acid over the range 1-4 molar; also recovery in 1 molar ammonium nitrate was about the same as in 1 molar HNO3. About a 100-fold increase in recovery was obtained by going from a convection stirred cell at 90°C to the pumped type of cell at 54°C using ammonium nitrate as the electrolyte.
Reflections on Pools: A pool of material in steady-state turnover is a collection of identical molecules from which deletions are made at a constant rate, along with simultaneous addition of new identical molecules at the same rate, the total pool size remaining unchanged. It is of interest to consider what may be expected in the way of such pools among the various chemical species which can be isolated from biological systems. It is clear what the model requires, i.e. any molecule belonging to the pool must have as much chance as any other pool molecule to make its exit. This situation is approximated by molecules in solution in a well mixed volume of fluid, hence the choice of the word "pool." The mixing brings pool molecules into proximity with the exit mechanism in a random way.
Reutilization of DNA-Thymine, and Conversion of RNA-Pyrimidines for DNA-Thymine, in Normal Rat Bone Marrow Studies with Tritiated Nucleosides: If one injects into an animal H3-thymidine, 50% of it is incorporated into deoxyribonucleic acid (DNA), within approximately 30 to 45 minutes, while the rest is catabolized. A storage of H3-thymidine for later incorporation into DNA does not occur, on the basis of available evidence. Once incorporated, the label remains bound to DNA until cell death and no unequivocal evidence has as yet been presented to indicate metabolic renewal or intracellular turnover of the DNA molecule. The loss of labeled DNA from the bone marrow is therefore directly influenced by the rate of proliferation of the various cell types with release of mature cells into the peripheral blood.
Secondary Tetanus Antitoxin Responses in Mice Elicited Prior to Irradiation: The pioneer study by Benjamin and Sluka in 1908 on inhibition of antibody formation by X-rays revealed the importance of the temporal relationship between exposure to radiation and injection of antigen. X-radiation delivered three days before injection of beef serum inhibited precipitin formation in rabbits. A similar exposure to X-rays delivered three days after injection of the antigen failed to repress production of specific antibody. These observations were partially confirmed in 1915 when Hektoen reported inhibition of hemolysin production in the rat when X-radiation was delivered either before or after injection of sheep red cells. Although an absolute difference in radiosensitivity was not evident, the depressant effect of radiation on antibody production appeared to be less effective when radiation was given after injection of the antigen.
A Simple Theory of the Process P+P → D+W+: The discovery of the vector meson which mediates the weak interactions, W,1 would be of extreme importance for weak interaction physics and for field theory in general. The W, if it exists, will be made in a variety of processes such as v+N →W+ + e- + N, or n- + P →W- + P, or, as studied in this note, P + P → D + W+. The W couples to leptons with a dimensionless constant [constant not transcribed] where G is the Feral constant defined t=so that [constant not transcribed]. Thus for [equation not transcribed] and the smallness of this constant is, evidently, what makes any of the above processes difficult to detect. The W may have a variety of decay modes.
The Simultaneous Labeling of Cells in Different Segments of the Mitotic Cycle with Tritiated Thymidine and Colchicine and the Effect of Colchicine on Thymidine Uptake: Treatment of Pisum root meristems with nutrient solutions containing tritiated thymidine (H3-T) and colchicine simultaneously labeled cells in two different segments of the mitotic cycle. Tracings of the serial progression of these differently labeled cells through mitosis resembled sine-cosine curves. When the labeled cells are in interphase the sign of the curves is negative, when they are in mitosis the sign is positive. The concept of the mitotic cycle in terms of trigonometric functions was presented as one way of transferring cycle from a celestial time scale to that of a biological clock.
Some Further Remarks on Beam Current Measurements in the AGS: A previous report on this subject (Brookhaven National Laboratory, AGS Internal Report, ECR-4) described in detail the methods of measuring the injected and accelerated proton currents in the Brookhaven AGS up to May 1961. At that time the accelerated current was measured by extracting the bunch frequency component of the signal given by a pair of radial position observation electrodes. The injected current was also determined by the signal induced on a similar pair of radial position electrodes. Absolute values were then determined from machine parameters and a wire measurement of the electrode sensitivities. Linac currents, however, were measured with transformers, calibrated by putting known current pulses through a single turn loop. As described in ECR-4, a crude current transformer was placed on the AGS ring and cross-calibration measurements were carried out using a half turn injected beam. The pickup electrode value was then found to be about 10% higher than that given by the current transformer. This amount of disagreement was within the estimated accuracy of the measurements and calibrations used at that time.
Some Problems in the Interpretation of Exponential Experiments: Buckling measurements at BNL have employed two experimental methods which in principle should yield identical results but in practice show a systematic and significant discrepancy. In this paper the experimental evidence of these errors is reviewed and their source is traced by means of theory to the radial flux transients which perturb the asymptotic neutron spectrum in the exponential assemblies. Some alternate and apparently more precise methods of analyzing the data are examined theoretically, including the possibility of anisotropy in the leakage probability.
Structure of HCrO2 and DCrO2: A neutron diffraction study of polycrystalline HCrO2 and DCrO2 (chromous acid) is described. Intensity data from the two substances were refined together by the least-squares method, with the constraint that the Cr-O distance be the same in the two substances. Estimates of individual contributions to multiple peaks were included in the least-squares refinement through the use of a non-diagonal weight matrix. The O-D-O bond is found to be asymmetric, O-D = 0.96 ± 0.04 A, O...O - 2.55 ± 0.02 A. The symmetry of the O-H-O bond cannot be determined, but agreement with observation is as good with a symmetric bond as with any other model. The O-H-O bond length is 2.49 ± 0.02 A. These results are consistent with those from previous studies of the HCrO2-DCrO2 system by nuclear magnetic resonance and infrared techniques.
Studies of the Binding of Insulin to a Muscle Cell Membrane Preparation: Recent studies suggest that the primary action of insulin is on the permeability of cell membranes. This idea may account for the effects of the hormone in broken cell preparations as well as in tissue preparations with intact cells if the concept of the cell membrane is broadened to include endoplasmic reticular extensions and the membranes of subcellular organelles. Following on the initial demonstration that insulin was bound to muscle and the elucidation of the structure of insulin, evidence was presented that this binding involves a sulfur-sulfur linkage between hormone and target tissue. In the present work, skeletal muscle cell ghosts were prepared for use in studying the chemical nature of the attachment of insulin to a relatively pure cell membrane preparation.
Studies of the Rapid Beam Ejector at the Cosmotron: For an experiment to measure the magnetic moment of the Λ hyperon, it was necessary to extract the external beam of the Cosmotron with maximum efficiency and with minimum time duration. To accomplish this end, the standard external beam of the machine was supplemented with the Rapid Beam Ejector. It was found that, unfortunately, the ejection efficiency of the beam was less than normal when the RBE was used. Measurements of the ejection efficiency were made by irradiating polyethylene foils at the second focus of Beam 1 with 3 BeV protons. The external beam was tuned up and optimized in a standard manner. It was found that the ratio of the number of protons ejected with the RBE to the number ejected without the RBE was 0.3 in one run and 0.22 in another try. It was also observed that the RBE did not shift the position of the external proton beam focus to within ± 1/8 in.
Study of Low Frequency Molecular Motions in HF, KHF2, KH2F3 and NaH2F3: The spectra of KHF2, KH2F3, NaH2F3, liquid and solid HF were measured between 1200 and 30 cm-1 by the inelastic scattering of "cold neutrons" (0.005e.v.). The spectrum of KHF2 is in agreement with previous infrared measurements and shows a peak at 147 mV corresponding to a deformation frequency v2 of the F-H-F group and a broad peak at 13 mV due to a libration of this group. The observed spectra for KH2F3, NaH2F3 solid and liquid HF were compared with that for KHF2 considering the known results that the F-F distance increases, the position of the H atom between the two fluorines becomes more asymmetrical, and the strength of the hydrogen bond decreases in going from the HF2- ion to H2F3- ion to HF. In this comparison the known structure of the H2F3- ion is considered as being intermediate between that of HF2- and the zig-zag hydrogen bonded chains in solid HF. As a result, the lines observed at 112 mV and 67 mV in the H2F3- spectra and in HF respectively are associated with the deformation frequency v2 of the H-F-H group in these compounds. In addition the spectra of H2F3- ions show a peak at a 15 mV attributed to a libration of the group. Both H2F3- and HF show peaks at 8 and 7 mV respectively attributed to a rotational motion of one F-H-F unit around the F-F bond. The observed spectrum of HF liquid, showing a high degree of association is also discussed with respect to these motions.
Theoretical Analysis of the Exponential Experiment in Natural Uranium: Methods of calculating the "Snell Experiment" (the exponential experiment in natural uranium) are examined. It is found that integral transport theory is required for accurate predictions. The effect of spatial transients upon measured quantities is studied and it is found that experiments have not been done in a large enough mass of uranium to achieve an asymptotic neutron distribution. However deviations from the asymptotic values of integral quantities are not large and corrections are calculated and applied to recent experiments. It is shown that the use of recent cross section data improves the agreement between theory and experiment. The relaxation length and all spectral indices are in fairly good agreement except for Np237 to U238 average fission cross section ratio.
Thermodynamics of Fused Salt Mixtures From EMF Measurements. The Systems NaCl-KCl, NaCl-MgCl2, and NaCl-CeCl3.: The following cells were operated at 820°C: [equations not transcribed] where the over-all reaction in each cell is simply the transfer of NaCl from pure NaCl to the mixtures of the right hand compartment. The porcelain acts as a pure sodium ion conductor in these cells. The relative partial molar free energy of mixing for sodium chloride, FMNaCl, is given by [equation not transcribed] where E is the EMF of the cell. Results are given over the entire composition range in each system and compared with previous measurements from other sources. Other thermodynamic quantities are calculated from the results. Experiments using a H2, HCl mixture in place of Cl2 are discussed, as well as the extension of the measurements to other systems.
A Time-Shared Computer Data Collection System at the Brookhaven Graphite Research Reactor: The increasing complexity of the data of nuclear physics has led to widespread interest in the possibility of utilizing a digital computer for on-line data collection. Through the combined efforts of the Instrumentation Division and the Neutron Physics group at Brookhaven such a system has been placed into operation. Several features of this system are believed to be unique and of interest to research groups centered about a major facility like a reactor or an accelerator.
Tissue Distribution and Storage Forms of Vitamin B12 Injected and Orally Administered to the Dog: Previous attempts by the present authors to compare the behavior of orally administered vitamin B12 with that of injected material have been inconclusive. Thus, 30 days after administration to normal humans, 0.19% of a tracer amount (0.5 μg) of injected radioactive vitamin B12 is excreted per day; and in an independent study, the eventual daily output was found to be 0.23% of a 3 μg dose. By contrast the total excretion rate of normal vitamin B12 from body stores appears to be only ≈0.03% per day. Such a divergence may result from incomplete mixing of radioactive vitamin B12 and body stores of the vitamin. Alternatively it may actually reflect the functioning of different compartments attending the several modes of administration involved. The possibility of degradation or transformation of vitamin within tissues and organs must also be considered.
Total Cross Sections for K Mesons and π Mesons on Protons and Deuterons between 2.5 and 6 BeV/c: Recent measurements of the pion-proton total cross section, taken with small statistical errors, have shown the existence of two new maxima in the momentum range between 2 and 3 BeV/c. Measurements of comparable statistical accuracy, covering the momentum range from 2.5 to 8 BeV/c are reported in the present paper. In addition to the total cross sections for π± mesons on protons, their total cross sections on deuterons have also been determined. Some data were also taken on the total cross sections for K+ mesons on protons and deuterons and for K- mesons on protons.
Total Neutron Average Cross Sections in the keV Region and the Optical Model: Many workers have recently attempted to evaluate the P-wave strength function from a measurement of average capture cross sections or average total cross sections in the kiloelectron volt region. The primary interest of these measurements has been to determine the strength of the spin-orbit potential in the optical model. In view of the interest in determining the size of the spin-orbit coupling and in view of the considerable disagreement group has undertaken to measure the average total neutron cross sections from 10 to 100 keV in the region of the P-wave giant resonance. The following elements were studied: Nb, Mo, Rh, Ag, Cd, and In. The wok was carried out at the BNL-AECL fast chopper facility at Chalk River, using an 88-meter flight path and a nominal resolution of 15 nsec/meter.
Trajectories for a Rectangular Magnet with Uniform Field: In connection with the design of a hodoscope system for the momentum analysis of secondary particles from a target bombarded by monoenergetic particles, it has been considered to use a large-aperature rectangular magnet with uniform field, and a hodoscope set of counters behind the magnet after a suitably long flight path of the particles. For accurate calibration of the momentum of the particles, it will probably be necessary to map very completely the field inside the magnet and the fringing fields at the entrance and exit boundaries, in order to calculate typical trajectories as a function of the position of the particle path at the entrance to the magnet, and the entrance angle and particle momentum. Nevertheless, for the sake of orientation, it may be useful to obtain the projections of the trajectory in the horizontal and vertical planes in the approximation that the effect of the fringing field can be represented by adding a correction to the length of the magnet and assuming that the field is uniform over the distance of the total effective length, and is zero outside the effective field boundaries. For treatment of the vertical motion, we will also assume that the object (source) lies in the median plane of the magnet. This condition will be approximately satisfied in the important practical case that the source is a target which is small in the vertical direction and from which the secondary particles are emitted.
Transport, Homeostasis and Specificity in Trace Metal Metabolism: A working definition of homeostasis is the following: the sum total of the processes which maintain a steady level of various substances or functions within a living baby. Our own concern will be with the homeostasis of trace metals. I will begin with a slide which shows the total body concentration of various metals, including "trace" ones. Only metallic constituents which play a role in the maintenance of the body's structure and function are shown. The essential trace metals among them are represented by black bars. Iron is both black and white. Indeed, if one excludes the fixed sequestered iron of myoglobin and of hemoglobin, one is left with a trace fraction of iron about which I will be talking later on. Note that the scale is logarithmic, indicating that the concentrations of essential metals in the body fall off sharply and smoothly.
Transport of FissionProducts Through the Soil Following Injection From a Well and Methods Used for Removal: In the summer of 1960 one of the little used wells on the Brookhaven National Laboratory site became accidentally contaminated with radioactive material. The contamination was discovered during a routine sampling of all wells in the waste disposal area, so there was a period of several weeks between the time of discharge.
The Ultraviolet Sensitivity of Frozen Phage: Recent reports (1, 2, 3, 4, 5) suggest that the crystalline structure of ice permits unusual forms of energy relationships and that the structured state of water may be of importance in the whole cell. A number of biologically interesting compounds show significantly altered responses to the excitation energy of ultraviolet light in ice as compared to the liquid state. This paper describes the effect of a change in phase state on a biologically active nucleoprotein, a bacteriophage particle. Phage is found to be much more sensitive to inactivation by ultraviolet light when irradiated in frozen aqueous suspension than when irradiated at room temperature (7): the sensitive target appears to be the phage DNA.
Use of a Digital Computer in the Development of a Positron Scanning Procedure: The problem to be discussed originates in our interest in the diagnosis and treatment of brain tumors. It has been established by others that some positron-emitting radioactive isotopes, in particular Arsenic-74 and Copper-64, can be causal to localize in brain tumors and thus to serve as agents for locating the tumors. Although other kinds of radioisotopes have also been used successfully in locating tumors, positron emitters have some especially attractive features. Their use is based on the principle that a positron, or positively charged electron, is a form of "anti-matter," and when it encounters an ordinary negatively charged electron both are annihilated, giving rise to two gamma rays that are emitted in opposite directions. Such an event is detectable through the use of coincidence counting. The data for which the method of analysis is to be discussed in the present paper is generated by a device using the coincidence counting method with multiple detectors in an arrangement potentially suitable for three-dimensional localization of brain tumors.
The Use of Low Energy Radioactive Isotopes in The Examination of Paintings on Thin Supports: The importance of the examination of paper and textile supported art objects by means of low energy X-rays has been ably discussed in the preceding papers of this session. The apparatus used for such radiography, however, has tended to be both expensive and confined to laboratory use. A lack of mobility arises from the weight and size of X-ray apparatus and the fact that its installation frequently requires shielding and special electric power lines. An inexpensive radiographic apparatus that required no special installation or external power and is small and light enough to be easily portable should be quite useful.
Use of Neutron Irradiations in the Brookhaven Mutations Program: In brief, these facilities consist of a 250 KvP X-ray generator; two areas of a research reactor, one a well thermalized unit of moderate capacity and a larger area with a mixed thermal and fast neutron distribution, all of which are used for brief, acute exposure. A 10 acre field, currently with almost 4000 curies of cobalt 60, serves to irradiate entire plants for either short or long periods of time. Recently, the flux density of the thermal column was increased by a factor of 5 over the original density. This was accomplished by lowering the thermal column 12 inches deeper into the reactor shield. Fast neutrons at this higher flux density are also available to the cooperator. An additional facility available to the program is the array of kilocurie gamma sources in the Nuclear Engineering Department of Brookhaven National Laboratory.
The Use of Tritiated Thymidine in the Study of Tissue Activation During Germination in Zea Mays L.: The transition from dormancy to growth in plant seeds has been the topic of many biological studies (1,2). Of particular interest to the radiobiologist are the dramatic changes in radiosensitivity occurring soon after the soaking of the seeds (3). These changes are thought to be associated with the commencement of proliferative activity. The recently developed method of labeling DNA with tritiated thymidine allows analysis of proliferative activity in greater detail than was heretofore possible. In the present study, uptake of tritiated thymidine and mitotic counts were used to determine the sequence of activation of proliferation in tissues or organs of the germinating corn embryo.
Wave Functions for Quadrupole Antishielding Factors: The purpose of this paper is to present tables of the perturbed wave functions which have been recently obtained in a calculation of the quadruple antishielding factors γ∞ for the Mn+2, Fe+3, Ga+3, and Ag+ ions. The wave functions v'1(nℓ-ℓ) which are tabulated represent the effect of the perturbation due to a nuclear quadruple moment Q on the wave functions of the outermost electrons of the ion core.
Ytterbium and Terbium Dodecaborides: The synthesis of several rare earth dodecaborides, isomorphous with UB12 and ZrB12, and crystallographic data for these phases were reported recently. The unit cells are face centered cubic with four formula weights of MeB12 per unit cell; the structures may be visualized in terms of boron atoms linked in a rigid three-dimensional network, with the metal atoms in large cubo-octahedral holes.

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