Focus drive mechanism for the IUE scientific instrument

A compact, lightweight mechanism was developed for in-orbit adjustment of the position of the secondary mirror (focusing) of the International Ultraviolet Explored telescope. This device is a linear drive with small (.0004 in.) and highly repeatable step increments. Extremely close tolerances are also held in tilt and decentering. The unique mechanization is described with attention to the design details that contribute to positional accuracy. Lubrication, materials, thermal considerations, sealing, detenting against launch loads, and other features peculiar to flight hardware are discussed. The methods employed for mounting the low expansion quartz mirror with minimum distortion are also given

Research notes: Significance of incompatibility reactions of Rhizobium japonicum strains with soybean host genotypes

Soybeans normally nodulate with Rhizobium japonicum and fix nitrogen in symbiotic association. However, several interactions, under genetic control, have been reported which result in ineffective nodulation or failure of the fixation process despite substantial nodule development. The recessive gene, rj1 , (Williams and Lynch, 1954) in homozygous mode, results in the exclusion from nodulation of a broad spectrum of Rhizobium jabonicum strains in soil culture

Research Notes: Genetic Studies of Soybean Host Cultivar Interactions with Rhizobium Strains

Several genetic factors have been identified which govern specific nodulation response in soybeans. The RJ2 genotype, carried by the cultivars \u27Hardee\u27 and \u27CNS,\u27 conditions an ineffective response in specific combination with Rhizobium japonicum strains of serogroups c1 and 122. The ineffective response is characterized as the development of either cortical proliferations on the roots or rudimentary nodules, rather than normal nodules

Breeding and Evaluation of Forage Soyabeans

The principal use of soyabean in the US in the early 1900s was as livestock forage. Soyabeans are less expensive to establish than small seeded perennial legume forages and can provide legume protein after winter killing of perennial legumes. Soyabean can improve production distribution by vigorous growth during the hot summer season when traditional perennial legumes are less productive

Research Notes : Genetic linkage analysis

The Rj2 gene (Caldwell, 1966), which conditions ineffective nodulation wtth strains of the cl and 122 serogroup of Rhizobium japonicum (Kirchner) Buhanan, and the Rj4 gene (Vest and Caldwell, 1972), conditioning an inef-fective nodulation response with rhizobial strain 61 of the Beltsville Culture Collection R. japonicum, were tested for linkage association with the gene L1 (black pod). The rj1 gene (Williams and Lynch, 1954), conditon-. ing a non-nodulating response with a broad spectrum of strains of R. Japonicum, was tested for linkage with the gene fr (roots nonfluorescent in UV light) and L1 (black pod). The gene y9 (chlorophyll defective) was tested for possible linkage with the genes ln (narrow leaf), and P1 (glabrous). The P1 gene was also tested for linkage with the gene fr

Research notes: Genetic analysis of factors controlling nodulation response in soybeans

Two of the genes controlling nodulation response in soybeans were tested for linkage associations with genes controlling pubescence color (T) and flower color (W1 ), chlorophyll deficiency (y9 ) and absence of pubescence (P). The rj1 gene (W1lliams and Lynch, 1954) in homozygous recessive condition results in a non-nodulating phenotype with a broad spectrum of Rhizobium japonicum strains. The dominant gene, Rj4 (Vest and Caldwell, 1972) conditions an ineffective nodulation response when inoculated specifically with R. japonicum strain 61 of the Beltsville Culture Collection

Research Notes: A technique for evaluating nodulation response of soybean genotypes with specific Rhizobium strains

Previous research on the interactions of Rhizobium strains with host cultivars has involved the testing of small numbers of plants with a specific strain of Rhizobium in Leonard jar assemblies (Leonard, 1943). The Leonard jar technique in our greenhouse requires frequent watering (up to twice daily) and periodic adjustment of the wick element. We have found the traditional Leonard jar assembly technique inadequate to efficiently accommodate the large plant populations required in plant selection and genetic studies of allelism and linkage

Research Notes: Vegetative Propagation of Soybeans

During the course of genetic studies of possible linkage associations involving factors controlling nodulation response in soybeans, we found it desirable to increase the size of the F2 population produced in the greenhouse during the winter. We endeavored to do this by vegetatively propagating the F1 hybrid plants for use in seed production. We visualize that vegetative propagation would also be useful for other purposes: (1) maintaining aneuploids which segregate at meiosis, and (2) providing propagules which may be subjected to different photoperiod regimes, thus providing coincidence of flowering in crosses of uncertain maturity when little seed is available

Research Notes : United States : Genetic linkage information

Descriptions of the genetic traits indicated by the gene symbols in Table 1 are given in the chapter on Qualitative Genetics in the Soybean Monograph (Bernard and Weiss, 1973). Recombination was calculated on F2 data us-ing the product method as described by Irrnner and Henderson (1943). All link-age combinations tested were found to follow independent assortment except the combination ln and p2

Does tiny-scale atomic structure exist in the interstellar medium ?

We report on preliminary results from the recent multi-epoch neutral hydrogen absorption measurements toward three pulsars, B0823+26, B1133+16 and B2016+28, using the Arecibo telescope. We do not find significant variations in optical depth profiles over periods of 0.3 and 9--10 yr, or on spatial scales of 10--20 and 70--85 AU. The large number of non detections of the tiny scale atomic structure suggests that the AU-sized structure is not ubiquitous in the interstellar medium and could be quite a rare phenomenon.Comment: Accepted by ApJ Letters, 5 pages, 2 figure