Technology Directions for the 21st Century

The Office of Space Communications (OSC) is tasked by NASA to conduct a planning process to meet NASA's science mission and other communications and data processing requirements. A set of technology trend studies was undertaken by Science Applications International Corporation (SAIC) for OSC to identify quantitative data that can be used to predict performance of electronic equipment in the future to assist in the planning process. Only commercially available, off-the-shelf technology was included. For each technology area considered, the current state of the technology is discussed, future applications that could benefit from use of the technology are identified, and likely future developments of the technology are described. The impact of each technology area on NASA operations is presented together with a discussion of the feasibility and risk associated with its development. An approximate timeline is given for the next 15 to 25 years to indicate the anticipated evolution of capabilities within each of the technology areas considered. This volume contains four chapters: one each on technology trends for database systems, computer software, neural and fuzzy systems, and artificial intelligence. The principal study results are summarized at the beginning of each chapter

Intuitive visualization of surface properties of biomolecules

In living cells, proteins are in continuous motion and interaction with the surrounding medium and/or other proteins and ligands. These interactions are mediated by protein features such as Electrostatic Potential (EP) and hydropathy expressed as Molecular Lipophilic Potential (MLP). The availability of protein structures enables the study of their surfaces and surface characteristics, based on atomic contribution. Traditionally, these properties are calculated by phisicochemical programs and visualized as range of colours that vary according to the tool used and imposes the necessity of a legend to decrypt it. The use of colour to encode both characteristics makes the simultaneous visualization almost impossible. This is why most of the times EP and MLP are presented in two different images. In this thesis, we describe a novel and intuitive code for the simultaneous visualization of these properties. For our purpose we use Blender, an open-source, free, cross-platform 3D application used for modelling, animation, gaming and rendering. On the basis of Blender, we developed BioBlender, a package dedicated to biological work: elaboration of proteins motion with the simultaneous visualization of their chemical and physical features. Blender's Game Engine, equipped with specific physico-chemical rules is used to elaborate the motion of proteins, interpolating between different conformations (NMR collections or different X-rays of the same protein). We obtain a physically plausible sequence of intermediate conformations which are the basis for the subsequent visual elaboration. A new visual code is introduced for MLP visualization: a range of optical features that goes from dull-rough surfaces for the most hydrophilic areas to shiny-smooth surfaces for the most lipophilic ones. This kind of representation permits a photorealistic rendering of the smooth spatial distribution of the values of MLP on the surface of the protein. EP is represented as animated line particles that flow along field lines, from positive to negative, proportional to the total charge of the protein. Our system permits EP and MLP simultaneous visualization of molecules and, in the case of moving proteins, the continuous perception of these features, calculated for each intermediate conformation. Moreover, this representation contributes to gain insight into the molecules function by drawing viewer's attention to the most active regions of the protein

TOWARDS THE UNDERSTANDING OF THE EFFECT OF FUNCTIONAL MONOMERS ON LATEX PARTICLE MORPHOLOGY FORMED BY EMULSION POLYMERIZATION

Emulsion polymerization is a multiphase reaction process and the overall kinetics depend on the reaction rates in both the aqueous and particle phases. The morphology development within composite latex particles is controlled by both kinetic and thermodynamic factors. Functional monomers like acrylic acid and 2-hydroxyethyl methacrylate are widely used in emulsion polymerization at low concentrations (usually \u3c 10% to total monomers) to improve various properties like shear and freeze thaw stability of the latex, adhesion of the polymer to metal and paper, and to create the possibility for post-polymerization chemical modifications. These monomers are highly water soluble and very much more polar than the commonly used acrylate and styrene monomers. This dissertation deals with the effect of such functional monomers on the reaction kinetics during the emulsion polymerization and on the resulting morphology of the composite latex particles. A detailed examination of the distribution behavior of vinyl acid and hydroxy (meth)acrylate functional monomers between the nonfunctional monomer phase and the aqueous phase is reported here. Due to the dimerization and multimer formation capabilities of vinyl acid and hydroxy (meth)acrylate monomer via hydrogen bonding, the distribution of these monomers between aqueous and organic phases can be highly concentration dependent. In addition, the distribution of vinyl acids is a strong function of pH. Common emulsion polymerization with functional monomers uses more than one nonfunctional monomer. We found that the distribution of functional monomers can be effectively predicted for multicomponent nonfunctional monomer mixtures using appropriate `mixing rules\u27. The distribution of a monomer between the aqueous phase and the polymer particle phase is normally estimated using monomer-polymer Flory-Huggins interaction parameters and we have carefully determined such parameters for the functional monomers and various polymers examined in this work. From the experimental and simulation studies for seeded emulsion copolymerizations with functional monomers, we found that both the aqueous phase and the particle phase kinetics are affected by these monomers. The functional monomers produced longer oligoradicals (Z-mers) in the water phase which then entered the particles to promote polymerization. Moreover, the distribution studies revealed an increase in the water phase monomer concentrations when these functional monomers were present. Both of these phenomena combined to result in an increase in the radical entry rate into the particles as compared to reactions without functional monomers under similar conditions. The particle morphologies obtained from seeded emulsion polymerizations with functional monomers were characterized and compared to those without the functional monomers. In these studies the levels of the functional monomers were varied between 0% and 10% and the polarity differences between the seed and second stage polymers changed in different directions depending on the particular system. For all of the systems studied, it was found that for the cases where the final particle morphology was either at or close to equilibrium (in terms of the minimization of free energy), the incorporation of the functional monomers did not impact the morphology significantly. However for the cases where the final morphologies were kinetically controlled, increases in the amount of functional monomer in a nonpolar second stage monomer increased the amount of phase mixing with a polar seed polymer

Estimated plant water use and crop coefficients for drip-irrigated hybrid polars

Estimations of plant water use can provide great assistance to growers, irrigators, engineers and water resource planners. This is especially true concerning the introduction of a new crop into irrigated agriculture. Growing hybrid poplar trees for wood chip stock and veneer production under agronomic practices is currently being explored as an alternative to traditional forestry practices. To this author's knowledge, no water use estimates or crop coefficients, the ratio of a specified crop evapotranspiration to a reference crop evapotranspiration, have been verified for hybrid poplars grown under drip irrigation. Four years of weekly, neutron probe measured, soil water data were analyzed to determine averaged daily, monthly and seasonal plant water use, or crop evapotranspiration. The plantation studied was located near Boardman, Oregon on the arid Columbia River Plateau of North-Central Oregon. Water was applied by periodic applications via drip irrigation. Irrigation application data, weekly recorded rainfall and changes in soil water content permitted the construction of a soil water balance model to calculate weekly hybrid poplar water use. Drainage was estimated by calculating a potential soil water flux from the lower soil profile. Sites with significant estimated potential drainage were removed from the analysis so that all sites used in the development coefficients were calculated using reference evapotranspiration estimates obtained from a nearby AGRIMET weather station. Mean crop coefficients were estimated using a 2nd order polynomial with 95% confidence intervals. Plant water use estimates and crop curves are presented for one, two and three year old hybrid poplars. Numerical simulation of irrigation practices was attempted using weekly soil water content and soil physical characterization data. Parameter optimization and numerical simulations were attempted using the HYDRUS-2D Soil Water and Solute Transport model. Parameter optimization and numerical simulations were largely unsuccessful due to lack of adequate soil physical and root zone system representation and dimensional differences between drip irrigation processes and the model design used in this study

Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties

The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids

Approaches to Macromolecular and Supramolecular Structure Determination

All of the common techniques for obtaining structural information from macromolecular and supramolecular objects suffer from one type of drawback or another. X-ray and neutron diffraction methods have the phase problem (only the amplitude and not the phase angle of the complex diffraction vector can be experimentally observed). Low-dose 3-dimensional electron microscopy suffers from the inability to collect a complete data set due to instrumental limitations. Although light microscopy allows the sample to be kept under biological conditions (compare with standard electron microscopic techniques), the low resolution has limited its appeal to more qualitative aspects of ultrastructure analysis. All of these limitations can be considered as a lack of information in the Fourier space domain. A generalized mathematical approach is presented where global real-space constraints are utilized to ameliorate this loss of information. In simple cases (one-dimensional analysis) it is possible to solve the phase problem, and in more complex cases (two- and three-dimensional analyses) the added real-space information is used to augment the experimentally derived data. The iterative Fourier refinement scheme was chosen as it represents the most versatile means for incorporating global knowledge concerning the real-space behavior of the object. This approach was used to solve the three-dimensional x-ray structure of the snake polypeptide neurotoxin α-Bungarotoxin, the one dimensional transmembrane electron density profile. for acetylcholine receptor containing membranes, and to solve the missing cone problem of electron microscopic structure analysis. Real-space constraints were also incorporated into an iterative deconvolution scheme used both for image processing and for the quantitative analysis of overlapping gel electrophoretogram peaks. None of this work would have been possible if the information supplied by real-space constraints had not been utilized . The approaches presented to these problems are general ones and should be applicable to other systems.</p

Investigations carried out under the Director's Discretionary Fund

This annual report comprises a set of summaries, describing task objectives, progress and results or accomplishments, future outlook, and financial status for each director's discretionary fund (DDF) task that was active during fiscal year 1984. Publications and conference presentations related to the work are listed. The individual reports are categorized as interim or final according to whether the task efforts are ongoing or completed. A partial list of new tasks to be initiated with fiscal year 1985 funds and a glossary of abbreviations and acronyms, used by the task authors in their summaries are included. The table of contents lists the DDF reports in sequence by their task number, which is derived from the 13-digit code assigned to account for the fund awarded to the task project