During the past five years, potentialities of space travel have greatly increased and new knowledge has become available regarding the nature of cosmic radiation. In the present article the knowledge pertinent to dose evaluation is reviewed for conditions of flight in space in the vicinity of the earth but away from the influence of its atmosphere or magnetic field. Certain properties of the heavy nuclei are also discussed as well as some of the available information on their actual biological effects. Development and completion of the new Heavy Ion Linear Accelerator allows extension of quantitative biological work with these particles. Finally, the statistical nature of the hazard from cosmic radiations and the limitations of space flight due to such rays are discussed.

The problem of photosynthesis is the problem of defining the way in which green plants are able to convert electromagnetic energy into chemical potential in the form of reduced carbon, usually as carbohydrate, and molecular oxygen. The use of tracer carbon, as carbon-14, has made possible considerable progress in the mapping of the routes taken by the carbon atom from CO2 into plant substances. The techniques of separation and identification that have made this progress possible lie largely in the region of chromatography and radioautography involving fractional-gamma amounts of material. A number of proposals have been made about the photochemical act itself. These proposals have led to the development of direct physical tests of their validity, and some results of these will be described.

Apparent [Sigma] hyperon decay events in a large emulsion stack of 240 9" x 12" pellicles have been classified into those judged to have occurred at rest and those in flight. Of 36 decay events at rest, 21 secondaries were observed to be protons of about 1675 microns range. Of the events decaying in flight, 23 were decays into protons and 46 were decays into near-minimum secondaries. Attempts have been made to trace the tracks of 35 of the lightly ionizing secondaries; the results of this effort are summarized in a table.

This is an attempt to summarize and relate at least some of the material presented in four talks during a symposium on radiobiological studies on yeast, and in addition discuss some related experimental results. The discussion will be divided into two sections: I) a discussion of the various manifestations of radiation damage in yeast; and II) a consideration of modification of these damages by variations of physico-chemical and biological parameters.

The basic investigation of transistor feedback amplifiers has proven mathematically simple and of great practical value. The behavior of single-stage common-emitter amplifiers is described and provides a building block with which cascaded feedback amplifiers can be analyzed and designed. From the results of this analysis the conditions for minimum drift for cascaded single-stages and cascaded loops have been derived.

The method of detecting unpaired electrons in liquid and solid systems by electron spin resonance is discussed. The significance of the hyperfine structure in electron spin resonance is discussed and the possible use of these structural features of the electron spin resonance spectrum to elucidate the nature of the photoproduced unpaired electrons in photosynthesizing systems is introduced.

This paper is intended as a preliminary report on the Homopolar configuration (axial magnetic field with radial electric field), which is the rotating configuration most thoroughly studied thus far. The analysis presented in this paper applies principally to the "ideal" Homopolar, that is, the configuration free from electrode-sheath drops and other disturbing but remediable phenomena. Design considerations for various interesting plasma appliances are derived and documented with preliminary experimental results. The experiments have been carried out under high-density (pinch-type) conditions which favor the creation of a totally rotating plasma and the actual physical measurement of the characteristics of such a plasma. When larger models of the Homopolar are built, it will be possible to use the present pinch-type technique of plasma formation at much lower density, just as has been done in the case of the toroidal stabilized pinch.

The present studies are carried out in order to elucidate the effect on enzyme activity of different kinds of radiation. Beams of protons and alpha particles from the Berkeley 60-inch cyclotron and beams of accelerated nuclei of helium, carbon 12, oxygen 16, and neon 20 from the Berkeley Heavy Ion Linear Accelerator (HILAC) have been used. With this variety of particles it has been possible to cover a range of LET 10 times greater than previously utilized in similar studies. The unattenuated energy of the different particles is exactly 10 MeV per nucleon for the HILAC radiation and approximately this value for the cyclotron radiation.

A general method is suggested for analyzing the scattering of particle A by particle B, leading to three or more final particles, in order to obtain the cross section for the interaction of A with a particle which is virtually contained in B. Binding complications are absent if a plausible assumption about the location and residues of poles in the S-matrix is accepted. The method is useful for unstable particles from which free targets cannot be made; the special examples of pion and neutron targets are discussed in detail.

The writer has initiated a comprehensive program of equipment development designed to give the maximum practical aid to the physicists and technicians who are carrying out track measurements. Some attention has also been given to developing systems of data handling using International Business Machine (IBM) equipment and Keysort cards. In addition, some of the steps to insure the accuracy of the emulsion data are taken long before the emulsion is studied under the microscope.

The basic information about the path of carbon in photosynthesis is reviewed, together with the methods that were used to discover it. This has led to the knowledge of what is required of the photochemical reaction in the form of chemical species. Attention is then directed to the structure of the photochemical apparatus itself insofar as it is viewable by electron microscopy, and some principles of ordered structure are devised for the types of molecules to be found in the chloroplasts. From the combination of these, a structure for the grana lamella is suggested and a mode of function proposed. Experimental test for this mode of function is underway; one method is to examine photoproduced unpaired electrons. This is discussed.

Existing experimental information about the nucleon-anitnucleon interaction is reviewed, and a description is given of a theoretical model, based on the Yukawa theory, which seems able to explain the experimental results.