Further studies of X-ray structure of the Perseus cluster

The X-ray sources in the Perseus cluster have been studied by many authors. Available data on the spatial and spectral distributions are examined and summarized. Based on these observations, a consistent model is proposed for the production of X-rays and gamma-rays in the region around NGC 1275. It is shown that good agreement with observations is obtained by assuming the emission of soft X-rays for thermal bremsstrahlung and of hard X-rays and gamma-rays from the inverse Compton process

PUBLIC POLICY RESPONSES TO INCREASED VERTICAL LINKAGES IN AGRI-FOOD SUPPLY CHAINS

vertical coordination, vertical linkage, public policy, agri-food supply chains, supply chain management, Agribusiness, Q1, L1,

Evaluation of actuator energy storage and power sources for spacecraft applications

The objective of this evaluation is to determine an optimum energy storage/power source combination for electrical actuation systems for existing (Solid Rocket Booster (SRB), Shuttle) and future (Advanced Launch System (ALS), Shuttle Derivative) vehicles. Characteristic of these applications is the requirement for high power pulses (50-200 kW) for short times (milliseconds to seconds), coupled with longer-term base or 'housekeeping' requirements (5-16 kW). Specific study parameters (e.g., weight, volume, etc.) as stated in the proposal and specified in the Statement of Work (SOW) are included

Coherent Exciton Lasing in ZnSe/ZnCdSe Quantum Wells?

A new mechanism for exciton lasing in ZnSe/ZnCdSe quantum wells is proposed. Lasing, occurring below the lowest exciton line, may be associated with a BCS-like condensed (coherent) exciton state. This state is most stable at low temperatures for densities in the transition region separating the exciton Bose gas and the coherent exciton state. Calculations show the gain region to lie below the exciton line and to be separated from the absorption regime by a transparency region of width, for example, about 80 meV for a 90 Angstrom ZnSe/Zn_(0.75)Cd_(0.25)Se quantum well. Experimental observation of the transparency region using differential spectroscopy would confirm this picture.Comment: 9 pages + 3 figs contained in 4 postscript files to appear Appl. Phys. Lett. March 13, 199

Identification and nucleotide sequences of mxaA, mxaC, mxaK, mxaL, and mxaD genes from Methylobacterium extorquens AM1

The DNA sequence for a 4.4-kb HindIII-XhoI Methylobacterium extorquens AM1 DNA fragment that is known to contain three genes (mxaAKL) involved in incorporation of calcium into methanol dehydrogenase (I. W. Richardson and C. Anthony, Biochem. J. 287:709-7115, 1992) was determined. Five complete open reading frames and two partial open reading frames were found, suggesting that this region contains previously unidentified genes. A combination of sequence analysis, mutant complementation data, and gene expression studies showed that these genes correspond to mxaSACKLDorf1. Of the three previously unidentified genes (mxaC, mxaD, and orf1), mutant complementation studies showed that mxaC is required for methanol oxidation, while the function of the other two genes is still unknown