Structural sizing considerations for large space structures

A number of missions for the space shuttle were proposed which involve placing large truss platforms on-orbit. These platforms range in size from tens of meters in span for reflector application to several thousand meters for solar power collector application. These proposed sizes and the operational requirements considered are unconventional in comparison to Earthbound structures and little information exists concerning efficient proportions of the structural elements forming the framework of the platforms. Such proportions are of major concern because they have a strong influence on the packaging efficiency and, thus, the transportation effectiveness of the shuttle. The present study is undertaken to: (1) identify efficient ranges of application of deployable and erectable platforms configured for shuttle transport to orbit, and (2) determine sensitivity to key parameters of minimum mass deployable and erectable platform designs

Observation of Spin Flips with a Single Trapped Proton

Radio-frequency induced spin transitions of one individual proton are observed for the first time. The spin quantum jumps are detected via the continuous Stern-Gerlach effect, which is used in an experiment with a single proton stored in a cryogenic Penning trap. This is an important milestone towards a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector

The MSW and the MPA: Confrontation of Two Professions in Public Welfare

From its inception in the 1930\u27s, public welfare has emerged as a major service industry commanding a sizeable portion of the public tax dollar. Concomitant with growth and size and expenditure has come the federalization of the program. In the face of a series of changes--the growth of welfare, added administrative complexity, and the emergence of new economic function--public welfare\u27s identification with social work was weakened. Correspondingly, and perhaps logically, its identification with public administration has been strengthened. In this paper, there is exploration of the changes leading to the confrontation between social work and public administration within public welfare. A comparative analysis of this confrontation is undertaken, and the methods of conflict resolution between the professions are explored. The principal purpose of the paper, however, is to draw attention to the argument, stimulate further debate about this course of events, and encourage some public policy direction in public welfare

Deployable and erectable concepts for large spacecraft

Computerized structural sizing techniques were used to determine structural proportions of minimum mass tetrahedral truss platforms designed for low Earth and geosynchronous orbit. Optimum (minimum mass) deployable and erectable, hexagonal shaped spacecraft are sized to satisfy multiple design requirements and constraints. Strut dimensions characterizing minimum mass designs are found to be significantly more slender than those conventionally used for structural applications. Comparison studies show that mass characteristics of deployable and erectable platforms are approximately equal and that the shuttle flights required by deployable trusses become excessive above certain critical stiffness values. Recent investigations of eractable strut assembly are reviewed. Initial erectable structure assembly experiments show that a pair of astronauts can achieve EVA assembly times of 2-5 min/strut and studies indicate that an automated assembler can achieve times of less than 1 min/strut for around the clock operation

Laser cooling of new atomic and molecular species with ultrafast pulses

We propose a new laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires single-frequency vacuum-ultraviolet light, while multielectron atoms need single-frequency light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and many other species appears feasible, and extension of the technique to molecules may be possible.Comment: revision of quant-ph/0306099, submitted to PR

Two-loop contributions of the order O alpha t alpha s to the masses of the Higgs bosons in the CP-violating NMSSM

We provide the two-loop corrections to the Higgs boson masses of the CP-violating NMSSM in the Feynman diagrammatic approach with vanishing external momentum at O alpha t alpha s. The adopted renormalization scheme is a mixture between DR¯$$\overline{\mathrm{DR}}$$ and on-shell conditions. Additionally, the renormalization of the top/stop sector is provided both for the DR¯$$\overline{\mathrm{DR}}$$ and the on-shell scheme. The calculation is performed in the gaugeless limit. We find that the two-loop corrections compared to the one-loop corrections are of the order of 5-10%, depending on the top/stop renormalization scheme. The theoretical error on the Higgs boson masses is reduced due to the inclusion of these higher order corrections