3,179 research outputs found
NASA Technology Demonstrations Missions Program Overview
The National Aeronautics and Space Administration (NASA) Fiscal Year 2010 (FY10) budget introduced a new strategic plan that placed renewed emphasis on advanced missions beyond Earth orbit. This supports NASA s 2011 strategic goal to create innovative new space technologies for our exploration, science, and economic future. As a result of this focus on undertaking many and more complex missions, NASA placed its attention on a greater investment in technology development, and this shift resulted in the establishment of the Technology Demonstrations Missions (TDM) Program. The TDM Program, within the newly formed NASA Office of the Chief Technologist, supports NASA s grand challenges by providing a steady cadence of advanced space technology demonstrations (Figure 1), allowing the infusion of flexible path capabilities for future exploration. The TDM Program's goal is to mature crosscutting capabilities to flight readiness in support of multiple future space missions, including flight test projects where demonstration is needed before the capability can transition to direct mission The TDM Program has several unique criteria that set it apart from other NASA program offices. For instance, the TDM Office matures a small number of technologies that are of benefit to multiple customers to flight technology readiness level (TRL) 6 through relevant environment testing on a 3-year development schedule. These technologies must be crosscutting, which is defined as technology with potential to benefit multiple mission directorates, other government agencies, or the aerospace industry, and they must capture significant public interest and awareness. These projects will rely heavily on industry partner collaboration, and funding is capped for all elements of the flight test demonstration including planning, hardware development, software development, launch costs, ground operations, and post-test assessments. In order to inspire collaboration across government and industry, more than 70% of the TDM funds will be competitively awarded as a result of yearly calls for proposed flight demonstrators and selected based on possible payoff to NASA, technology maturity, customer interest, cost, and technical risk reduction. This paper will give an overview of the TDM Program s mission and organization, as well as its current status in delivering advanced space technologies that will enable more flexible and robust future missions. It also will provide several examples of missions that fit within these parameters and expected outcomes
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Towards computer supported cooperative design
This thesis first reviews the literature about the nature of cooperative design activity and its technological support. It is noted that knowledge of how designers work together in real-world settings is less than complete. Moreover, after over a decade of developments in Computer Supported Cooperative Work, the state-of-the-art in collaborative technology does not fully support such activities. Two substantial case studies are presented. The first draws upon fieldwork with designers at a large, distributed engineering design company, where a pilot study of collaborative technologies was carried out, focusing on the organisational context for such interventions and the reasons behind the qualified success of the experimental technology. In the light of the lack of use of synchronous tools in particular, a second case study was carried out. This was a complementary analysis of face-to-face co-working in a series of meetings held by a small design group. The results of both pieces of fieldwork are analysed in the context of existing studies of designers in both real-world and laboratory settings. This leads to the identification of a number of important characteristics of cooperative design, some newly identified, others confirming or extending the results of existing work. They include the identification of tension between traditional engineering design culture and the underlying assumptions of new technology; the intrinsic difficulties in sharing some types of design artefacts; and the way in which design entails an interweaving of individual and group activity, with consequences for resource exploitation, distributed cognition and workspace navigation in group sessions. The findings are integrated into an organising framework for cooperative design, with emphasis on the support of coworking designers distributed across multiple sites. Current technologies are reviewed against scenarios based on the framework and recommendations are made for further work
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Molecular Recognition of Damaged DNA Using Synthetic Affinity Reagents
Potentially carcinogenic DNA damage that may be derived from dietary sources can be quantified using a number of methods. Some of the best of these methods are based on the use of antibodies that have high affinity and specificity for modified DNA bases. However, given the sometimes limited availability of antibodies there is a requirement for novel reagents that mimic the properties of the best antibodies. From a chemical perspective antibodies are 'over engineered' and synthetic affinity reagents would recreate the optimal properties of the binding site with respect to selectivity and affinity.
Phage display was used to identify amino acid residues that contribute to recognition of a diet derived DNA adduct O6-carboxymethyl-2'-deoxyguanosine. However, this information was not sufficient to synthesise a novel peptide reagent directly and it was decided to develop an approach whereby a library of compounds was synthesised which includes the characteristics expected within the binding site of an antibody. This library was based around cholic acid, a readily available scaffold molecule with suitable functionality compatible with linking amino acids and a fluorescent tag.
A synthetic procedure based on the formation of stable oxime derivatives of cholic acid was optimised and a small library of pyrene-tagged trisubstituted cholic acid derivatives was characterised. The library was examined for its ability to bind to affinity columns containing immobilised O6-carboxymethylguanosine and there was some evidence that indicated specific binding of a subset of library molecules
"Functional analysis of the prokaryotic metallothionein locus, smt"
The localisation of the prokaryotic metallothionein (MT) divergon smt (which includes the MT gene smtA and a divergently transcribed gene smtB] was examined, and smt deficient mutants of Synechococcus PCC 7942 (strain R2-PIM8) have been generated by insertional inactivation/partial gene deletion mediated by homologous recombination. The structure and homozygosity (of the smt region) of these mutants, designated R2-PIM8(smt), was confirmed by Southern analyses and plasmid recovery in Escherichia coli (involving the generation of a ca. 7.8 kb plasmid from Soil digested R2-PIM8(smt) DNA). Furthermore, smtA transcripts were not detected in R2-PIM8(smt) RNA. Viability of R2-PIM8(smt) reveals that smt performs no essential role in Synechococcus under these culture conditions. R2-PIM8(smt) has reduced tolerance to Zn(^2+) and Cd(^2+), and short term reduced resistance to Ag(^+). Restoration of Zn(^2+) tolerance was used as a phenotypic selection to isolate recombinants derived from R2-PIM8(smt) after reintroduction of a linear DNA fragment containing an uninterrupted smt divergon. These smt-restored cells also exhibited restored Cd(^2+) tolerance. Hypersensitivity to Cu(^2+) or Hg(^2+)was not detected in R2-PIM8(smt) indicating independence of Cu(^2+) and Hg(^2+) resistance to smt-mediated metal tolerance. Sequences upstream of smtA (Including smtB and/or the smt operator-promoter) fused to a promoterless locZ, conferred metal-dependent β-galactosidase expression in R2-PIM8. At maximum permissive concentrations for growth, β-galactosidase assays revealed Zn(^2+) to be a more potent elicitor of metal-dependent expression from the smtA operator-promoter than Cd(^2+). Equivalent experiments, in R2-PIM8(smQ and R2-PIM8(smtA+/B-) (containing functional chromosomal smtA and non-functional chromosomal smtB), revealed that smtB encodes a repressor of smtA transcription. In addition, it is demonstrated that SmtB can act in trans. It is proposed that Zn(^2+) is the most potent (metal ion) inducer of SmtB mediated derepression of smtA transcription. Furthermore, β-galactosidase assays indicated that, in addition to SmtB, other regulatory elements (including a transcriptional activator) are involved in the regulation of expression from the smt operator-promoter. Restoration of Zn(^2+) tolerance was also used as a phenotypic selection to isolate recombinants derived from R2-PIM8(smt) after reintroduction of a linear DNA fragment, containing functional smtA and non-functional smtB. The resulting transformants, R2-PIM8(smtA+/B-), exhibited increased (early) tolerance to Zn(^2+) and Cd(^2+) as compared to R2-PIM8(smt-. reintroduced ) (equivalent to R2-PIM8).The work presented in this thesis proposes a role for SmtA in Zn(^2+) homoeostasis/metabolism and Cd(^2+) detoxification. SmtB is confirmed to be a trans-acting inducer- (metal ion) responsive negative regulator of smtA. The phenotype of R2-PIM8(sm(A+/B-) (with respect to metal tolerance) has significance regarding previous work (Gupta et al., 1993. Molecular Microbiology 7, 189-195), in which analysis of the smt region of Synechococcus PCC 6301 cells selected for Cd(^2+) resistance, by stepwise adaptation, revealed the functional deletion of smtB. It was proposed that loss of smtB may be beneficial for continuously metal challenged cells. Loss of smtB, now shown to encode a repressor of smtA transcription, is shown to confer constitutive derepressed expression from the smtA operator- promoter and determine an (early) increase in metal (Zn(2+)/Cd(^2+)) tolerance
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