Preliminary design-lift/cruise fan research and technology airplane flight control system

This report presents the preliminary design of a stability augmentation system for a NASA V/STOL research and technology airplane. This stability augmentation system is postulated as the simplest system that meets handling qualities levels for research and technology missions flown by NASA test pilots. The airplane studied in this report is a T-39 fitted with tilting lift/cruise fan nacelles and a nose fan. The propulsion system features a shaft interconnecting the three variable pitch fans and three power plants. The mathematical modeling is based on pre-wind tunnel test estimated data. The selected stability augmentation system uses variable gains scheduled with airspeed. Failure analysis of the system illustrates the benign effect of engine failure. Airplane rate sensor failure must be solved with redundancy

The role of dietary polyphenols in the moderation of the inflammatory response in early stage colorectal cancer

Current focus in colorectal cancer management is on reducing overall mortality by increasing the number of early stage cancers diagnosed and treated with curative intent. Despite the success of screening programmes in down-staging colorectal cancer, interval cancer rates are substantial and other strategies are desirable. Sporadic colorectal cancer is largely associated with lifestyle factors including diet. Polyphenols are phytochemicals ingested as part of a normal diet which are abundant in plant foods including fruits/berries and vegetables. These may exert their anti-carcinogenic effects via the modulation of inflammatory pathways. Key signal transduction pathways are fundamental to the association of inflammation and disease progression including those mediated by NF-κB and STAT, PI3K and COX. Our aim was to examine the evidence for the effect of dietary polyphenols intake on tumour and host inflammatory responses to determine if polyphenols may be effective as part of a dietary intervention. There is good epidemiological evidence of a reduction in colorectal cancer risk from case-control and cohort studies assessing polyphenol intake. It would be premature to suggest a major public health intervention to promote their consumption however, dietary change is safe and feasible, emphasising the need for further investigation of polyphenols and colorectal cancer risk

Involving patients in decisions about preventive medication : A focus group study

Original article can be found at: http://www.pccj.eu/ Copyright Sherborne Gibbs Ltd. [reproduced here with permission of publishers]Background: Patients may have unrealistic expectations of preventive treatment and frequently do not take long-term medication. Involvement of the patient in the decision to start such medication may improve this, but enabling an informed decision is notoriously difficult. Aims: To explore patients' perceptions of preventive medication, the desire for informed choice and how this could best be achieved. Method: Purposive sampling was used to select patients registered with one of two general practices in South England. Audio recording, transcription and computer-assisted textual analysis were conducted for focus group discussions. Results: This was a small study, but the majority of focus group participants who had been prescribed a preventive medication said they received very little or no information about benefits and disadvantages when it was started. Some felt that doctors did not want to share information. Older participants thought that choice was over-rated, trusted their doctor to recommend appropriate medication and did not necessarily wish to be involved in the decision. Younger participants wanted to be more involved. However, even those who expressed little interest in involvement felt that personalised information compared with population norms comparing individuals to the 'average person' would be helpful. Written information specific to the individual and on how the medication or lifestyle changes might affect them was considered welcome. Conclusions: Doctors need to be sensitive to patients' preferences for involvement in the decision-making process and for the way information on risk is shared. Providing written information specific to the individual patient is likely to facilitate shared decisions about preventive medication.Peer reviewedFinal Published versio

Bar-Halo Friction in Galaxies II: Metastability

It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at resonances. While some particles gain and others lose, friction arises when there is an excess of gainers over losers. This imbalance results from the generally decreasing numbers of particles with increasing angular momentum, and friction can therefore be avoided if there is no gradient in the density of particles across the major resonances. Here we show that anomalously weak friction can occur for this reason if the pattern speed of the bar fluctuates upwards. After such an event, the density of resonant halo particles has a local inflexion created by the earlier exchanges, and bar slowdown can be delayed for a long period; we describe this as a metastable state. We show that this behavior in purely collisionless N-body simulations is far more likely to occur in methods with adaptive resolution. We also show that the phenomenon could arise in nature, since bar-driven gas inflow could easily raise the bar pattern speed enough to reach the metastable state. Finally, we demonstrate that mild external, or internal, perturbations quickly restore the usual frictional drag, and it is unlikely therefore that a strong bar in a galaxy having a dense halo could rotate for a long period without friction.Comment: 13 pages, 11 figures, to appear in Ap

Space Transportation System Meteorological Expert

Computers are being used today to build the expert systems of tomorrow. Expert systems are computer programs that are smart about a domain in the way that people are smart. Expert systems technology is being applied to weather forecasting to support Shuttle operations for launch and for ground processing at Kennedy Space Center (KSC), Florida. The Space Transportation System Meterological ExperT (STSMET) is a long term project, now-in its third year, to capture general Shuttle operational weather forecasting expertise specific to our locale, to apply it to Shuttle operational weather forecasting tasks at the Cape Canaveral Forecast Facility (CCFF) at the Cape Canaveral Air Force Station (CCAFS), and to ultimately provide an on-line, real-time operational aid to the duty forecasters in performing their tasks. The first domain addressed by the project has been summer thunderstorms. The effort to represent this knowledge and a control structure to reason about it has resulted in an approach that we call scenario-based reasoning. Other meteorological domains on our agenda are frontal weather phenomena, visibility including fog, and wind shear. We believe that scenario-based reasoning is also applicable to these other meteorological domains. The specific operational tasks to which to apply the general knowledge about summer thunderstorms are being identified during this phase of the contract. The project is being developed using state-of-the-art hardware and software: a Symbolics Lisp Machine, Zetalisp and Automated Reasoning Tool (ART), an expert system shell. Scenario-based reasoning appears to have applications outside of weather forecasting. The abilities of a scenario-based system to reason qualitatively, to reason over time, and to reason across scale are all applicable to planning in autonomous systems. With further research, we expect to add analogical reasoning to the abilities of scenario-based reasoning

7-Li(p,n) Nuclear Data Library for Incident Proton Energies to 150 MeV

We describe evaluation methods that make use of experimental data, and nuclear model calculations, to develop an ENDF-formatted data library for the reaction p + Li7 for incident protons with energies up to 150 MeV. The important 7-Li(p,n_0) and 7-Li(p,n_1) reactions are evaluated from the experimental data, with their angular distributions represented using Lengendre polynomial expansions. The decay of the remaining reaction flux is estimated from GNASH nuclear model calculations. The evaluated ENDF-data are described in detail, and illustrated in numerous figures. We also illustrate the use of these data in a representative application by a radiation transport simulation with the code MCNPX.Comment: 11 pages, 8 figures, LaTeX, submitted to Proc. 2000 ANS/ENS International Meeting, Nuclear Applications of Accelerator Technology (AccApp00), November 12-16, Washington, DC, US

Decay of Superflow Confined in Thin Torus: A Realization of Tunneling Quantum Fields

The quantum nucleation of phase slips in neutral superfluids confined in a thin torus is investigated by means of the collective coordinate method. We have devised, with numerical justification, a certain collective coordinate to describe the quantum nucleation process of a phase slip. Considering the quantum fluctuation around the local minimum of the action, we calculate the effective mass of the phase slip. Due to the coherence of the condensate throughout the torus, the effective mass is proportional to the circumference L of the torus, and the decay rate has a strong exponential L-dependence.Comment: 4 pages, 2 figures, REVTe

Cob Development in Forage Maize: Influence of Harvest Date, Cultivar and Plastic Mulch

Forage maize grown for silage tends to be a compromise between reproductive and vegetative yield, and the cob component is the main driver of feeding value (Keane et al., 2003). Thus the aim is to produce a well-developed crop of high dry matter (DM) and starch content reflecting large cobs of well-filled grains rather than crops with low DM and starch contents reflecting poorly developed (immature) cob components at harvest. The use of plastic mulch can increase total DM yields with the increase in cob yield accounting for 75% of the total yield increase (Easson & Fearnehough, 1997). In this experiment the composition of cob components (i.e. rachis plus kernel) of two cultivars of different maturity under Irish conditions grown with or without plastic mulch were monitored between the harvest dates of 10 September to 9 November