Thermal-distortion analysis of a spacecraft box truss in geostationary orbit

The Mission to Planet Earth enlists the use of a geostationary platform to support Earth science monitoring instruments. The strongback for a proposed geostationary platform is a deployable box truss that supports two large diameter passive microwave radiometer (PMR) and several other science instruments. A study was performed to estimate the north-south and east-west pointing errors at the mounting locations of the two PMRs due to on-orbit thermal distortions of the main truss. The baseline configuration indicated that the east-west pointing error greatly exceeded the required limits. Primary origins of the pointing errors were identified, and methods for their reduction were discussed. Thermal performance enhancements to the truss structure were modeled and analyzed, including state-of-the-art surface coatings and insulation techniques. Comparisons of the thermal enhancements to the baseline were performed. Results demonstrated that using a thermal enclosure insulating technique reduced external heat fluxes, and distributed those heat fluxes more evenly throughout the structure, sufficiently reducing the pointing error to satisfy pointing accuracy requirements for the PMR's

Conceptual design of a synchronous Mars telecommunications satellite

Future missions to Mars will require a communications system to link activities on the Martian surface with each other and with mission controllers on Earth. A conceptual design is presented for an aerosynchronous communications satellite to provide these links. The satellite provides the capability for voice, data/command, and video transmissions. The mission scenario assumed for the design is described, and a description of a single aerosynchronous satellite is explained. A viable spacecraft design is then presented. Communication band selection and channel allocation are discussed. The communications system conceptual design is presented along with the trades used in sizing each of the required antennas. Also, the analyses used to develop the supporting subsystem designs are described as is the communications impact on each subsystem design

A Bit-String Model for Biological Aging

We present a simple model for biological aging. We studied it through computer simulations and we have found this model to reflect some features of real populations.Comment: LaTeX file, 4 PS figures include

A family of filters to search for frequency dependent gravitational wave stochastic backgrounds

We consider a three dimensional family of filters based on broken power law spectra to search for gravitational wave stochastic backgrounds in the data from Earth-based laser interferometers. We show that such templates produce the necessary fitting factor for a wide class of cosmological backgrounds and astrophysical foregrounds and that the total number of filters required to search for those signals in the data from first generation laser interferometers operating at the design sensitivity is fairly smallComment: 4 pages, 4 figures, uses iopart.cls, accepted for publications on Classical and Quantum Gravity (Special Issue, Proceedings of Amaldi 2003

Economic Analysis of Children's Surgical Care in Low- and Middle-Income Countries: A Systematic Review and Analysis.

BackgroundUnderstanding the economic value of health interventions is essential for policy makers to make informed resource allocation decisions. The objective of this systematic review was to summarize available information on the economic impact of children's surgical care in low- and middle-income countries (LMICs).MethodsWe searched MEDLINE (Pubmed), Embase, and Web of Science for relevant articles published between Jan. 1996 and Jan. 2015. We summarized reported cost information for individual interventions by country, including all costs, disability weights, health outcome measurements (most commonly disability-adjusted life years [DALYs] averted) and cost-effectiveness ratios (CERs). We calculated median CER as well as societal economic benefits (using a human capital approach) by procedure group across all studies. The methodological quality of each article was assessed using the Drummond checklist and the overall quality of evidence was summarized using a scale adapted from the Agency for Healthcare Research and Quality.FindingsWe identified 86 articles that met inclusion criteria, spanning 36 groups of surgical interventions. The procedure group with the lowest median CER was inguinal hernia repair ($15/DALY). The procedure group with the highest median societal economic benefit was neurosurgical procedures ($58,977). We found a wide range of study quality, with only 35% of studies having a Drummond score ≥ 7.InterpretationOur findings show that many areas of children's surgical care are extremely cost-effective in LMICs, provide substantial societal benefits, and are an appropriate target for enhanced investment. Several areas, including inguinal hernia repair, trichiasis surgery, cleft lip and palate repair, circumcision, congenital heart surgery and orthopedic procedures, should be considered "Essential Pediatric Surgical Procedures" as they offer considerable economic value. However, there are major gaps in existing research quality and methodology which limit our current understanding of the economic value of surgical care

Stochastic background from extra-galactic double neutron stars

We present Monte Carlo simulations of the extra galactic population of inspiralling double neutron stars, and estimate its contribution to the astrophysical gravitational wave background, in the frequency range of ground based interferometers, corresponding to the last thousand seconds before the last stable orbit when more than 96 percent of the signal is released. We show that sources at redshift z>0.5 contribute to a truly continuous background which may be detected by correlating third generation interferometers.Comment: 13 pages, 7 figures - proceeding of a talk given at the 11th GWDAW, to appear in CQ