An Ecological Comparison of Two Types of Woodland (A Preliminary Report)

During parts of the growing seasons of 1924 and 1925 a preliminary study has been made of two types of woodland in the vicinity of Cedar Falls, Iowa. In later studies, now under way, an attempt will be made to determine more accurately the structure of these woodlands and to correlate the differences in structure with the ecological factors

Investigation of the dc-excited xenon laser final report, 24 mar. 1964 - 24 mar. 1965

Electron energy spectra in gas laser discharges and investigation of new discharge configuration

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma X-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays, while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y onto a thin formvar film or by extracting the sample (with or without an internal standard) onto ion exchange resin which is pressed into a pellet

Infrared properties of dust grains derived from IRAS observations

The analysis of several diffuse interstellar clouds observed by the Infrared Astronomy Satellite (IRAS) is presented. The 60/100 micron flux ratios appear to be nearly constant in clouds with up to 1 sup m visual extinction at the center. Observations of a highly regular cloud in Chamaeleon show that the 12/100 micron ratio peaks at an intermediate radial distance and declines towards the center of the cloud. These observations indicate that nonequilibrium emission accounts only for the 12 and 25 micron bands; strong emission observed at the 60 micron band is probably due to equilibrium thermal radiation. The correlation of the 12 micron emission with a red excess observed for a high latitude cloud, L1780, is shown to be consistent with the assumption that both features are due to fluorescence by the same molecular species

Dust emission from high latitude cirrus clouds

In order to study dust emission from grains in the interstellar medium, the infrared properties were analyzed in a number of isolated high latitude dust clouds which contain no dominant internal heating sources. The clouds are spatially resolved, have a simple geometry, and are mapped in the IRAS bands at 12, 25, 60, and 100 microns. For a number of these clouds, extinction data (A sub B) were obtained from starcounts. A large part (30 to 50 percent) of the infrared radiation of the clouds in the IRAS wavelength range of 8 to 130 micron is emitted in the short wavelength bands at 12 and 25 micron. The 60/100 micron ratios for the integrated fluxes of the clouds have a typical value of 0.19 + or - 0.05

Inheritance of aluminum tolerance in maize.

In a set of 3 experiments, a number of parental lines and various of their hybrid and backcross generations (from crosses of tolerant and sensitive lines) were raised in nutrient solution containing 195 umol Al/litre. An analysis of relative seminal root lengths showed than additive gene effects contributed most to genetic variation in Al tolerance, with dominance effects accounting for only half as much varation. Epistatic effects were minor. The frequency distributions of tolerance in the F2 were typical of a quantitatively inherited trait. There was a tendency for non-tolerance to be dominant over tolerance although this was not consistent. Analysis of the F1 from a diallel cross among 8 inbred lines indicated that general combining ability variance explained most of the variation, but specific combining ability effects were significant in each case

Operational Problems with Large Space Boosters

THE LAST TWO YEARS have seen the vigorous inauguration by the United States of an ambitious program for the exploration of space. This multi-pronged effort, under the direction of the National Aeronautics and Space Administration, is critically dependent upon the successful development of a new generation of large boosters, far greater in size than any missile or booster previously developed. The concept of the NASA Merritt Island launch facilities and the basic principles of the test operations that will be conducted there have been discussed in a number of recent papers but the operational problems that will be encountered in the use of such facilities have ha.d little discussion and indeed it is still too early in the stage design and ground support equipment design of the Saturn V vehicle to define these problems in any detail. Using, however, the known dimensions of the Saturn V vehicle and the published characteristics of the Merritt Island Launch Area as examples, it is possible to make a general study of the nature of the operational problems that will be encountered during the testing, checkout, and launch of such large space vehicles

The Formation and Fragmentation of Disks around Primordial Protostars

The very first stars to form in the Universe heralded an end to the cosmic dark ages and introduced new physical processes that shaped early cosmic evolution. Until now, it was thought that these stars lived short, solitary lives, with only one extremely massive star, or possibly a very wide binary system, forming in each dark matter minihalo. Here we describe numerical simulations that show that these stars were, to the contrary, often members of tight multiple systems. Our results show that the disks that formed around the first young stars were unstable to gravitational fragmentation, possibly producing small binary and higher-order systems that had separations as small as the distance between the Earth and the Sun.Comment: This manuscript has been accepted for publication in Science. This version has not undergone final editing. Please refer to the complete version of record at http://www.sciencemag.org

Final-state interactions in the response of nuclear matter

Final-state interactions in the response of a many-body system to an external probe delivering large momentum are normally described using the eikonal approximation, for the trajectory of the struck particle, and the frozen approximation, for the positions of the spectators. We propose a generalization of this scheme, in which the initial momentum of the struck particle is explicitly taken into account. Numerical calculations of the nuclear matter response at 1 $< |{\bf q}| <$ 2 GeV/c show that the inclusion of this momentum dependence leads to a sizable effect in the low energy tail. Possible implications for the analysis of existing electron-nucleus scattering data are discussed.Comment: 21 pages, 4 figure