Supporting flight data analysis for Space Shuttle Orbiter experiments at NASA Ames Research Center

The space shuttle orbiter experiments program is responsible for collecting flight data to extend the research and technology base for future aerospace vehicle design. The infrared imagery of shuttle (IRIS), catalytic surface effects, and tile gap heating experiments sponsored by Ames Research Center are part of this program. The software required to process the flight data which support these experiments is described. In addition, data analysis techniques, developed in support of the IRIS experiment, are discussed. Using the flight data base, the techniques provide information useful in analyzing and correcting problems with the experiment, and in interpreting the IRIS image obtained during the entry of the third shuttle mission

On Being Relevant to the Future of IS Practice

In this essay, we argue that being relevant to practice must imply a concern with influencing future IS practices. Discussions of IS research relevance, however, are rarely explicit about how research is meant to shape the future. Drawing on Feenberg’s (2002) critical theory of technology and his concepts of primary-secondary instrumentalization and potentialities, we consider how IS research about the past can inform the future of IS practice. We then explore implicit assumptions about shaping the future in positivism, interpretivism and critical research, and consider how design science and action research may be addressing technological potentialities. We draw attention to Zald’s (1993) enlightenment model as an alternative to suggest how IS researcher might be more open to research approaches drawn from the humanities for social and technical critique. We conclude by considering the feasibility of our suggestions

An Economic Evaluation of Venous Thromboembolism Prophylaxis Strategies in Critically Ill Trauma Patients at Risk of Bleeding

Using decision analysis, Henry Stelfox and colleagues estimate the cost-effectiveness of three venous thromboembolism prophylaxis strategies in patients with severe traumatic injuries who were also at risk for bleeding complications

Enhanced Practical Photosynthetic CO₂ Mitigation

This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO2 uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization

Distributed Load Balancing in the Presence of Node Failure and Network Delays

In this paper, we present a new dynamic, and adaptive distributed load balancing algorithm. This algorithm is able to handle the loss of some computational nodes, the connectivity of the network, and the variations in tasks and transfer delays. An experimental verification of the algorithm is presented using PlanetLab

Flow-Controlling Header

An apparatus and method for holding a membrane, screen or other flexible planar body in tension, while providing a conduit for water or other liquid to flow to the membrane being held. The membrane extends from inside a manifold body that carries the liquid, and the manifold body supports the membrane at one edge while the membrane is pulled in tension. Liquid pressure builds up inside the manifold body, preferably by entering a pressure chamber at the top of the manifold body. At a feeding pressure in the pressure chamber the liquid is distributed to the membrane for microbe growth. The liquid can be elevated to a higher, microbe-harvesting pressure by increasing the pressure in the pressure chamber, thereby deflecting a shim separating the pressure chamber from the membrane. The change in pressure is carried out by manually or automatically opening and closing a conventional water valve

Apparatus and Method for Growing Biological Organisms for Fuel and Other Purposes

A bioreactor apparatus in which a container has sidewalls, a floor and a ceiling defining a chamber that contains a slurry of water, nutrients and photosynthetic microorganisms. A plurality of optical fibers, each of which has a first end disposed outside the chamber and a second end in the mixture. A light collector spaced from the container has light incident on it and focuses the light onto the first ends of the plurality of optical fibers, thereby permitting the light to be conveyed into the mixture to promote photosynthesis. At least one nozzle is in fluid communication with a source of gas, such as exhaust gas from a fossil-fuel burning power plant containing carbon dioxide. The nozzle is disposed in the mixture beneath the second ends of the optical fibers for injecting the gas into the mixture

Dynamic time delay models for load balancing, Part II: A stochastic analysis of the effect of delay uncertainty

In large-scale distributed computing systems, in which the computational elements are physically or virtually distant from each other, there are communication-related delays that can significantly alter the expected performance of load-balancing policies that do not account for such delays. This is a particularly significant problem in systems for which the individual units are connected by means of a shared broadband communication medium (e.g., the Internet, ATM, wireless LAN or wireless Internet). In such cases, the delays, in addition to being large, fluctuate randomly, making their one-time accurate prediction impossible. In this work, the stochastic dynamics of a load-balancing algorithm in a cluster of computer nodes are modeled and used to predict the effects of the random time delays on the algorithm’s performance. A discrete-time stochastic dynamical-equation model is presented describing the evolution of the random queue size of each node. Monte Carlo simulation is also used to demonstrate the extent of the role played by the magnitude and uncertainty of the various time-delay elements in altering the performance of load balancing. This study reveals that the presence of delay (deterministic or random) can lead to a significant degradation in the performance of a load-balancing policy. One way to remedy such a problem is to weaken the load-balancing mechanism so that the load-transfer between nodes is down-scaled (or discouraged) appropriately

The effect of time delays on the stability of load balancing algorithms for parallel computations

A deterministic dynamic nonlinear time-delay system is developed to model load balancing in a cluster of computer nodes used for parallel computations. The model is shown to be self consistent in that the queue lengths cannot go negative and the total number of tasks in all the queues and the network are conserved (i.e., load balancing can neither create nor lose tasks). Further, it is shown that using the proposed load balancing algorithms, the system is stable in the sense of Lyapunov. Experimental results are presented and compared with the predicted results from the analytical model. In particular, simulations of the models are compared with an experimental implementation of the load balancing algorithm on a distributed computing network

Incidence of sexually transmitted infections during pregnancy

Prevalence of sexually transmitted infections (STI) is high among pregnant women in certain settings. We estimated STI incidence and compared STI risk in pregnant and non-pregnant women. Data came from the Methods for Improving Reproductive Health in Africa (MIRA) study conducted in South Africa and Zimbabwe 2003–2006. Women aged 18–50 years with at least one follow-up visit within 6 months of enrollment were included. Follow-up visits included laboratory testing for pregnancy, chlamydia, gonorrhea, trichomoniasis, and HIV, as well as self-report of hormonal contraceptive (HC) use, sexual behaviors and intravaginal practices. All visits were classified according to pregnancy status. Incidence of each STI was calculated using follow-up time. Cox proportional hazards models were fitted using pregnancy as a time-varying exposure and sexual behaviors and intravaginal practices as time-varying covariates. Among 4,549 women, 766 (16.8%) had a positive pregnancy test. Median follow-up time was 18 months [IQR: 12–24]. The overall incidence rate of chlamydia was 6.7 per 100 person years (py) and 9.9/100py during pregnancy; gonorrhea incidence was 2.7/100py and 4.9/100py during pregnancy; trichomoniasis incidence was 7.1/100py overall and 9.2/100py during pregnancy. Overall HIV incidence was 3.9/100py and 3.8/100py during pregnancy. In crude models, pregnancy increased risk for chlamydia (hazard ratio (HR) 1.5, 95%CI: 1.1–1.2), however there was no increased risk of any measured STI in adjusted models. STI Incidence was high during pregnancy however pregnancy did not increase STI risk after adjustment for sexual behaviors. Greater efforts are needed to help pregnant women avoid STIs