29,357 research outputs found
The Cultivation of Hydrogen-fixing Bacteria Quarterly Status Report, 1 Jul. - 30 Sep. 1966
Optimum environmental conditions steady state growth of hydrogen fixing bacteria culture
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Three-dimensional cometary dust coma modelling in the collisionless regime: strengths and weaknesses
Inverse coma and tail modelling of comets based on the method developed by Finson & Probstein is commonly used to analyse cometary coma images. Models of this type often contain a large number of assumptions that may not be constrained unless wide temporal or spectral coverage is available and the comets are bright and at relatively small geocentric distance. They are used to predict physical parameters, such as the mass distribution of the dust, but rarely give assessments of the accuracy of the estimate. A three-dimensional cometary dust coma model in the collisionless regime has been developed to allow the effectiveness of such models to constrain dust coma properties to be tested. The model is capable of simulating the coma morphology for the following input parameters: the comet nucleus shape, size, rotation, emission function (including active fraction and jets), grain velocity distribution (and dispersion), size distribution, dust production rate, grain material and light scattering from the cometary dust.
Characterization of the model demonstrates that the mass distribution cannot be well constrained as is often assumed; the cumulative mass distribution index ? can only be constrained to within ±0.15. The model is highly sensitive to the input grain terminal velocity distribution so model input can be tested with a large degree of confidence. Complex secondary parameters such as jets, rotation and grain composition all have an effect on the structure of the coma in similar ways, so unique solutions for these parameters cannot be derived from a single optical image alone. Multiple images at a variety of geometries close in time can help constrain these effects.
The model has been applied to photometric observations of comets 126P/IRAS and 46P/Wirtanen to constrain a number of physical properties including the dust production rate and mass distribution index. The derived dust production rate (Qdust) for 46P/Wirtanen was 3+7/1.5 kg s1 at a pre-perihelion heliocentric distance of 1.8 au, and for P/IRAS was 50+100/20 kg s1 at a pre-perihelion heliocentric distance of 1.7 au; both comets exhibited a mass distribution index ? = 0.8 ± 0.15
New Records of Five Ground Beetles From Ohio (Coleoptera: Carabidae)
Five ground beetles (Carabidae), Carabus sylvosus, Elaphrus americanus, Cyclotrachelus incisus, Piesmus submarginatus and Amara crassispina are reported from Ohio for the first time
Improved apparatus for continuous culture of hydrogen-fixing bacteria
Improved apparatus permits the continuous culture of Hydrogenomonas eutropha. System incorporates three essential subsystems - /1/ environmentally isolated culture vessel, /2/ analytical system with appropriate sensors and readout devices, /3/ control system with feedback responses to each analytical measurement
Semiclassical description of the kinematically complete experiments
Based on the semiclassical, impact parameter method a theoretical model is
constructed to calculate totally differential cross sections for single
ionization of helium by impact with fast C ions. Good agreement with the
experiment is achieved in the scattering plane, while in the perpendicular
plane a similar structure to that observed experimentally is obtained. The
contribution of different partial waves to the cross section is also
investigated.Comment: 9 pages, 6 figure
Systems approach to evaluating Hydrogenomonas cultures
Hydrogenomonas cultures investigated for metabolic waste utilization in aerospace life support system
Engineering requirements for culturing of Hydrogenomonas bacteria
Cultivation of Hydrogenomonas for waste management in closed cycle life support syste
Shuttle system ascent aerodynamic and plume heating
The shuttle program provided a challenge to the aerothermodynamicist due to the complexity of the flow field around the vehicle during ascent, since the configuration causes multiple shock interactions between the elements. Wind tunnel tests provided data for the prediction of the ascent design heating environment which involves both plume and aerodynamic heating phenomena. The approach for the heating methodology based on ground test firings and the use of the wind tunnel data to formulate the math models is discussed
DCU at the TREC 2008 Blog Track
In this paper we describe our system, experiments and re-
sults from our participation in the Blog Track at TREC
2008. Dublin City University participated in the adhoc re-
trieval, opinion finding and polarised opinion finding tasks.
For opinion finding, we used a fusion of approaches based
on lexicon features, surface features and syntactic features.
Our experiments evaluated the relative usefulness of each of
the feature sets and achieved a significant improvement on
the baseline
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