Design and test of field programmable gate arrays in space applications

Field Programmable Gate Arrays (FPGAU's) offer substantial benefits in terms of flexibility and design integration. In addition to qualifying this device for space applications by establishing its reliability and evaluating its sensitivity to radiation, screening the programmed devices with Automatic Test Equipment (ATE) and functional burn-in presents an interesting challenge. This paper presents a review of the design, qualification, and screening cycle employed for FPGA designs in a space program, and demonstrates the need for close interaction between design and test engineers

What makes a planet habitable?

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane–ethane surface lakes on Saturn’s large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life

Time trends in antiretroviral treatment use in Australia, 1997-2000

Objectives: To assess how developing knowledge surrounding combination antiretroviral treatment for people living with HIV infection since mid-1 996 has altered how drugs are used in Australia. Methods: Time trends in use of antiretroviral treatment were calculated on patients recruited to the Australian HIV Observational Database. For each six month period, patients were on one or more antiretroviral drugs for at least two weeks. Other patients were in the no-treatment group. Patients receiving antiretrovirals for more than two weeks were allocated to the category of treatment (mono, double or triple-plus therapy) they received for the longest period. Results: 1476 patients were recruited by September 2000. Of patients currently receiving antiretroviral therapy, 32 per cent took three or more antiretrovirals including an HIV protease inhibitor (PI) and 27 per cent took triple-plus therapy including a nonnucleoside reverse transcriptase inhibitor (NNRTI). The proportion of patients receiving regimens containing stavudine (D4T) decreased from 60 per cent in January to June 1999 to 46 per cent in July to September 2000. The proportion of patients receiving zidovudine (AZT) increased slightly from 26 per cent to 30 per cent. The addition of ritonavir to PI- containing regimens increased from 12 per cent in January to June 1999 to 33 per cent in July to September 2000. The proportion of patients ceasing treatment also increased. By July to September 2000, 10 per cent of patients had ceased treatment for more than three months. Conclusion: Antiretroviral treatment use has changed in Australia. Whether these changes are associated with improved clinical outcomes remains uncertain