NASA rocket motor defects investigation. Volume 2 - Tables and figures Comprehensive report, Aug. 1966 - Jun. 1968

Static firing tests to reduce glass fiber defects and to improve field repair work on X-248 rocket motor case - Supporting tables and figure

NASA rocket motor defects investigation. Volume 3 - Appendices Comprehensive report, Aug. 1966 - Jun. 1968

Static firing tests to reduce glass fiber defects and to improve field repair work on X-248 rocket motor cases - Inspection, repair and firing dat

Optically Pumped Direct Extraction Electron Spin Filter System and Method of Use

Disclosed are a System, and method, for producing a directly extracted flow of preferred-spin-polarization-direction electrons. The present invention optically pumped electron Spin filter System provides a mixture of, typically alkali, atoms and electron polarization direction enhancing buffer gas, to a, preferably, Single chamber essentially enclosed Space, into which essentially enclosed space is entered a predominately single handedness, preferably laser System produced, beam of photons which optically pumps electrons in atoms to a dark-ground State with a preferred-spin-polarization, that is maintained in the presence of an imposed magnetic field, which magnetic field is oriented essentially co-linear with said beam of predominately single polarized photons. Con-currently electrons are, by practice of the method of the present invention, generated in the essentially enclosed space by a buffer gas mediated electric discharge, and are caused to be in a preferred-spin-polarization-direction via pumped dark-ground State atom-electron collision mediated exchange mechanism(s), prior to being directly extracted

Optically Pumped Electron Spin Filter

This paper reports the first experimental demonstration of an optically pumped electron spin filter. Unpolarized electrons produced in a cold-cathode discharge drift through a mixture of spin-polarized Rb and a nitrogen or helium buffer gas. Through spin-exchange collisions with the Rb, the drifting electrons become polarized along the optical pumping axis. We study the role of the buffer gas in both the optical pumping and the spin transfer to the free electrons. This spin filter produces electron beams with currents and polarizations comparable to first-generation GaAs polarized electron sources

Pattern formation driven by nematic ordering of assembling biopolymers

The biopolymers actin and microtubules are often in an ongoing assembling/disassembling state far from thermal equilibrium. Above a critical density this leads to spatially periodic patterns, as shown by a scaling argument and in terms of a phenomenological continuum model, that meets also Onsager's statistical theory of the nematic--to--isotropic transition in the absence of reaction kinetics. This pattern forming process depends much on nonlinear effects and a common linear stability analysis of the isotropic distribution of the filaments is often misleading. The wave number of the pattern decreases with the assembling/disassembling rate and there is an uncommon discontinuous transition between the nematic and the periodic state.Comment: 4 pages, 3 figure

Spatial variation in western corn rootworm (Coleoptera: Chrysomelidae) susceptibility to Cry3 toxins in Nebraska

Repeated use of field corn (Zea mays L.) hybrids expressing the Cry3Bb1 and mCry3A traits in Nebraska has selected for field-evolved resistance in some western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) populations. Therefore, this study was conducted to characterize spatial variation in local WCR susceptibility to Cry3Bb1 and mCry3A traits in Keith and Buffalo counties, Nebraska, and determine the relationship between past management practices and current WCR susceptibility. Adult WCR populations were collected from sampling grids during 2015 and 2016 and single-plant larval bioassays conducted with F1 progeny documented significant variation in WCR susceptibility to Cry3Bb1 and mCry3A on different spatial scales in both sampling grids. At the local level, results revealed that neighboring cornfields may support WCR populations with very different susceptibility levels, indicating that gene flow of resistant alleles from high trait survival sites is not inundating large areas. A field history index, comprised of additive and weighted variables including past WCR management tactics and agronomic practices, was developed to quantify relative selection pressure in individual fields. The field history index-Cry3 trait survivorship relationship from year 1 data was highly predictive of year 2 Cry3 trait survivorship when year 2 field history indices were inserted into the year 1 base model. Sensitivity analyses indicated years of trait use and associated selection pressure at the local level were the key drivers of WCR susceptibility to Cry3 traits in this system. Retrospective case histories from this study will inform development of optimal resistance management programs and increase understanding of plant-insect interactions that may occur when transgenic corn is deployed in the landscape. Results from this study also support current recommendations to slow or mitigate the evolution of resistance by using a multi-tactic approach to manage WCR densities in individual fields within an integrated pest management framework

Inorganic impact modifier and processing aid for PVC

An amorphous silica, SIDISTAR has been investigated as an impact modifier for rigid PVC. Optimal dispersion of the silica as primary particles is essential and this can be achieved by incorporating it at an early stage of the mixing process before other fillers are added. This ensures that the PVC grains are coated with SIDISTAR. This material is able to function as an impact modifier via the cavitation mechanism and it will also improve the dispersion of the other ingredients in the compound. It was found that SIDISTAR delayed gelation of the PVC compound, but this could be avoided by minor changes in formulation and processing conditions. Reduction in gelation time resulted in improved impact performance. Furthermore, compounds containing SIDISTAR possessed a wide processing window

Spectroscopy of 13B via the 13C(t,3He) reaction at 115 AMeV

Gamow-Teller and dipole transitions to final states in 13B were studied via the 13C(t,3He) reaction at Et = 115 AMeV. Besides the strong Gamow-Teller transition to the 13B ground state, a weaker Gamow-Teller transition to a state at 3.6 MeV was found. This state was assigned a spin-parity of 3/2- by comparison with shell-model calculations using the WBP and WBT interactions which were modified to allow for mixing between nhw and (n+2)hw configurations. This assignment agrees with a recent result from a lifetime measurement of excited states in 13B. The shell-model calculations also explained the relatively large spectroscopic strength measured for a low-lying 1/2+ state at 4.83 MeV in 13B. The cross sections for dipole transitions up to Ex(13B)= 20 MeV excited via the 13C(t,3He) reaction were also compared with the shell-model calculations. The theoretical cross sections exceeded the data by a factor of about 1.8, which might indicate that the dipole excitations are "quenched". Uncertainties in the reaction calculations complicate that interpretation.Comment: 11 pages, 6 figure