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.

Tissue from etiolated or partially etiolated Pisum seedlings is widely used in work on growth substances and light responses. However, in the authors' experience growth under the conditions commonly employed is frequently irregular, and often affords little or no satisfactory experimental material. Although the literature records little evidence of such difficulties, personal communication with many investigators leaves no doubt they are widespread.

The crystal structure of MgSO4·4H2O has been refined using single crystal neutron diffraction data for the three main zones. The hydrogen positions which were found are essentially those which have been deduced from X-ray data in an earlier investigation.The mean value of the O-H bond lengths is 0.97Å. The O-H-O bonds are bent considerably. One hydrogen atom does not participate in hydrogen bonding, as can be concluded from the geometry of its surroundings and its thermal motion.

In high-energy particle physics the initial problem is to obtain information about the behavior of particles which are invisible by any known means (the radius of a proton is 10-13 cm) and which may be traveling at speeds greater than 180,000 miles per second, but at less than the speed of light. Some of the work is being done with the use of electronic counters, but the larger fraction is currently done by three techniques which employ the photographic process. These are the silver halide emulsion stack, the liquid hydrogen bubble chamber and the spark chamber. Counters provide immediate information but it is of a yes-or-no character, whereas the other methods are capable of actually mapping, with varying degrees of accuracy, an interaction between particles. The emulsion stack is quite familiar and need be discussed only briefly. Since individual silver halide crystals are rendered developable along the paths of charged particles, a sensitive detector may be built up with thick layers of specially sensitized emulsion having no base support. As the path of the particle may be through several emulsion having no base support. as the path of the particle may be through several emulsion layers and the track must …

The scope of the AGS complex has expanded rapidly during the three years since an accelerated beam was first obtained. Demand for research time far exceeds the amount available although facilities have been much increased. At the same time, experiments are being designed which are more complicated than previous ones and which make more stringent demands on the accelerator and on its auxiliary equipment. There is a continuous trend of experiments to particle beams of greater momentum, as the experimental techniques are refined. This use of increased momentum means that larger areas are required for the apparatus and that more power is necessary for the magnetic optics. All beam-sharing at the AGS is done by multiple use of each accelerated pulse because our experience indicates that pulse-by-pulse beam-sharing is relatively inefficient. (Expansion chambers have seldom been used at the AGS.) The problems of scheduling experiments becomes increasingly complex since combinations must be found satisfying the criteria: maximum number of experiments to run simultaneously; minimum downtime to be taken for rearrangement between successive experimental arrays

Binary fluorides of the type XMnF3 (X= Na, Rb, Cs, and NH4), which were investigated previously by means of x-ray, electron spin resonance specific heat, and magnetization measurements, have been reported to be antiferromagnetic. The present study reports powder neutron diffraction measurements on these compounds undertaken to confirm the antiferromagnetism and to study details of the magnetic ordering. Some information was also obtained concerning the nuclear structures.

A feedback technique has been developed to equalize the DC levels of two signal sources so that AC signal components which are much smaller than the DC levels can be compared accurately without introducing a low frequency cut-off and consequent rate-dependency into the system. A digital integrator in the feedback loop provides a highly stable long-term "memory" so that the correct level will be maintained during intervals when the signals are "frozen" at some arbitrary point.

In the vast field of radiation pathology we find pathologists, anatomists, and even physiologists busily at work, but the radiobiologist is conspicuously absent, although, according to Zirkle (1959), this field is clearly within his domain. Perhaps it is wise to take this broad hint of the scientifically so well equipped radiobiologist and to stay clear from an area in which an incalculable array of variables makes clearcut experimentation a hopeless venture, a priori. Perhaps it would be better if the pathologist, who must study pertinent material, restricts himself humbly to the recording of his observations, refraining from any attempt at interpretation. On the other hand, since seemingly audacious speculation has borne fruit in the past and the value of the information that results, if the speculation proves to be correct, is worth many times the effort, there is obvious justification for a thesis on the mechanism of delayed radionecrosis.

At this, the XI International Congress of Genetics, the major portion of the program has been devoted to synopsis, in which outstanding problems of modern genetics have been discussed. It required vision on the part of the Organizing Committee to conceive such a program for an international congress; and it required courage, a great deal courage, to schedule 25 symposium on a 6 meeting days. But the vision and courage have been amply rewarded. The symposia were outstanding, and have contributed toward making this Congress a strikingly successful gathering.

Evidence is rapidly accumulating that the genetic material carried in a chromosome is arranged in a highly organized manner. The nucleotides of DNA constituting a gene are grouped in sequence, like the letters of a word, and presumably each word uniformly consists of three letters. Successive words make up a sentence containing the information needed to build a protein molecule. Each word of the sentence is transcribed to form an amino acid of the protein for which the particular gene is responsible.

The kinetics of several oxidation-reduction reactions involving manganese (III) have been studied spectrophotometrically by the use of a flow technique. The free energies of activation for the oxidation of various substituted tris-(1,10-phenanthroline) complexes of iron (II) by manganese (III) in perchloric acid and in pyrophosphoric-sulfuric acid media were found to be linearly related to the standard free energy changes of the reactions. The application of the Marcus theory to the reactions of manganese (III) with iron (II) and with various substituted iron (II)-phenanthroline complexes and to the reaction of cobalt (III) with manganese (II) in perchloric acid leads to an estimate of about 10 -4 F -1 sec -1 for the rate constant of the manganese (II)-manganese (III) electron exchange reaction at 25.0°. Attempts to determine the rate constant for this exchange by a radioactive tracer method were unsuccessful.

The duration of mitosis is of great importance in an evaluation of growth rates in proliferating somatic tissues, since calculations are based on observations of mitotic activity, and therefore final results are directly proportional to an assumed value for mitotic time. This duration cannot be measured directly in vivo at a tissue level, since the mode of distribution of the single cell value is not known. This difficulty is not overcome in extrapolations from in vitro measurements. Also it is not overcome with the labeling of proliferating cells after tritiated thymidine injection in vivo if subsequent observation is limited to the rate of progression into mitosis of labeled cells that incorporated the tracer during the period of DNA-synthesis. Observation of separate mitotic phases, however, offers the possibility of following the progression of the wave of labeled cells at successive, short-lasting checking steps, and to analyze the variability in the times of passage through mitosis. In the present work, the progression of labeled cells as a function of time, after a single injection of tritiated thymidine, was followed in successive phases of mitosis in erythroblasts of dog bone marrow.

Studies on a large variety of plant species, particularly by Sparrow and his colleagues, have shown that radiosensitivity, as measured by growth inhibition and lethality, is strongly correlated with various parameters of the cell nucleus. Foremost among these are nuclear volume, SNA content and chromosome number. It is generally accepted that in proliferating cell systems chromosome damage may well be the principal radiobiological lesion, and the observed correlations are in line with the contention that loss of genetic materials following such fragmentation is a factor of a major importance in radiation-induced lethality and growth inhibition in plants.

The development of nuclear arms added the effects of ionizing radiation to the direct and indirect mechanical, chemical or thermal hazards of "conventional" weapons. The biological effects of ionizing radiation are the result of absorption of energy and the morphologically recognizable damage is poorly understood. Although new in their use in weapons and difficult to evaluate in their consequences, ionizing radiations are by no means new to physicians. Furthermore, medical experience has shown that clinical consequences of radiation injury are similar to those with which the clinician has to deal with every day in the treatment of neoplastic disorders and its complications. Soon after the discovery of x-rays by Roentgen and of the phenomenon of radioactivity by Bequerrel in the last decade of the last decade of the 19th century, it was found that ionizing radiation can produce marked biological effects by interfering with cell- and organ functions. Senn and Hussey were the first to effectively treat leukemia by this means. This, since about 60 years, ionizing radiation has been a powerful tool in the hands of physicians both in diagnostic procedures and for therapy of malignant disease. It should not be forgotten however, that the price paid for this …

In a continuation of the study of the properties of the φ meson we have roughly doubled the available data on the φ production via the reactions [equations were not transcribed]. The data discussed here was obtained in the Brookhaven National 20" Hydrogen Bubble Chamber exposed at a separated beam of K- of 2.24 Gev/c.

Monoclinic FeSO4·7H2O is the stable solid phase between -1.82° and 56.6° C in contact with a saturated water solution of FeSO4. It occurs in nature as an oxidation product of Fe-containing sulfides an is called melanterite. FeSO4·7H2O belongs to a series of compounds Me2+SO4·nH2O, where Mn2+ is a cation with an approximate ionic radius of 0.7Å. The 1-, 4- and 5-hydrates are known to crystalize each in only one form, whereas the hexa- and the heptahydrates occur both in two different forms. The crystal structure of the tetragonal NiSO4·6H2O; Zalkin, Ruben and Templeton reported the structure of the monoclinic CoSO·6H2O. Of the structure of the heptahydrates but one was described: the orthorhombic form of NiSO4·7H2O. No details were known about one of the monoclinic heptahydrates, though Leonhardt and Ness published the cell constants and the space group of FeSO4·7H2O.. In addition they stated essentially correct positional parameters for the sulfur atom and gave the correct positions of the iron atoms. The present investigation has been undertaken as part of an extensive study of salt hydrates. A preliminary account has been published before.

The experimental measurements of electron ejection in Po210 decay are discussed, and the theory of the process is outlined. The order-of-magnitude discrepancy between theory and experiment which was evident a decade ago has not yet been definitively resolved. The discrepancy is ascribed to an inadequacy of the theory, in particular to the use of an asymptotic expansion in that theory. Brief mention is made of some very recent unpublished calculations by G. W. Schaefer in which a reasonable estimate of the K ejection probability is obtained by a procedure that avoids the asymptotic expansion.

A study has been made of entrainment generation in a submerged coil evaporator and a vertical-tube natural circulation evaporator. Both evaporators generated about the same amount of entrainment at comparable boil-up rates. The decontamination efficiency of a submerged coil evaporator is correlated to the boil-up rate. The efficiency of a bubble-cap column, a Raschig ring packed tower, and a glass wool packed tower as de-entrainment devices was studied, the glass wool packed tower proving to be the most effective.