Conducting a Self-Assessment of a Long-Term Archive for Interdisciplinary Scientific Data as a Trustworthy Digital Repository

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PresentationsDate: 2009-05-19 03:00 PM – 04:30 PMLong-term preservation and stewardship of scientific data and research-related information is paramount to the future of science and scholarship. Disciplinary and interdisciplinary scientific data archives can offer capabilities for managing and preserving data for research, education, and decision-making activities of future communities representing various scientific and scholarly disciplines. However, meeting the requirements for a trusted digital repository presents challenges to ensure that archived collections will be discoverable, accessible, and usable in the future. Assessing whether scientific data archives meet the requirements for trustworthy repositories will help to ensure that todayâ s collections of scientific data will be available in the future. A continuing self-assessment of a long-term archive for interdisciplinary scientific data is being conducted to identify improvements needed to become a trustworthy repository for managing and providing access to interdisciplinary scientific data by future communities of users. Recommendations are offered for archives of scientific data to meet the requirements of a trustworthy repository.NAS

When Does Learning in Games Generate Convergence to Nash Equilibria? The Role of Supermodularity in an Experimental Setting

This study clarifies the conditions under which learning in games produces convergence to Nash equilibria in practice. Previous work has identified theoretical conditions under which various stylized learning processes achieve convergence. One technical condition is supermodularity, which is closely related to the more familiar concept of strategic complementarities. We experimentally investigate the role of supermodularity in achieving convergence through learning. Using a game from the literature on solutions to externalities, we systematically vary a free parameter below, close to, at and beyond the threshold of supermodularity to assess its effects on convergence. We find that supermodular and ¡°near-supermodular¡± games converge significantly better than those far below the threshold. From a little below the threshold to the threshold, the improvement is statistically insignificant. Within the class of supermodular games, increasing the parameter far beyond the threshold does not significantly improve convergence. Simulation shows that while most experimental results persist in the long run, some become more pronounced.learning, supermodular games

Abrupt bifurcations in chaotic scattering : view from the anti-integrable limit

Bleher, Ott and Grebogi found numerically an interesting chaotic phenomenon in 1989 for the scattering of a particle in a plane from a potential field with several peaks of equal height. They claimed that when the energy E of the particle is slightly less than the peak height Ec there is a hyperbolic suspension of a topological Markov chain from which chaotic scattering occurs, whereas for E > Ec there are no bounded orbits. They called the bifurcation at E = Ec an abrupt bifurcation to chaotic scattering. The aim of this paper is to establish a rigorous mathematical explanation for how chaotic orbits occur via the bifurcation, from the viewpoint of the anti-integrable limit, and to do so for a general range of chaotic scattering problems

Influence of dynamic inflow on the helicopter vertical response

A study was conducted to investigate the effects of dynamic inflow on rotor-blade flapping and vertical motion of the helicopter in hover. Linearized versions of two dynamic inflow models, one developed by Carpenter and Fridovich and the other by Pitt and Peters, were incorporated in simplified rotor-body models and were compared for variations in thrust coefficient and the blade Lock number. In addition, a comparison was made between the results of the linear analysis, and the transient and frequency responses measured in flight on the CH-47B variable-stability helicopter. Results indicate that the correlations are good, considering the simplified model used. The linear analysis also shows that dynamic inflow plays a key role in destabilizing the flapping mode. The destabilized flapping mode, along with the inflow mode that the dynamic inflow introduces, results in a large initial overshoot in the vertical acceleration response to an abrupt input in the collective pitch. This overshoot becomes more pronounced as either the thrust coefficient or the blade Lock number is reduced. Compared with Carpenter's inflow model, Pitt's model tends to produce more oscillatory responses because of the less stable flapping mode predicted by it

CRISPR/Cas9-mediated gene manipulation to create single-amino-acid-substituted and floxed mice with a cloning-free method.

Clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology is a powerful tool to manipulate the genome with extraordinary simplicity and speed. To generate genetically modified animals, CRISPR/Cas9-mediated genome editing is typically accomplished by microinjection of a mixture of Cas9 DNA/mRNA and single-guide RNA (sgRNA) into zygotes. However, sgRNAs used for this approach require manipulation via molecular cloning as well as in vitro transcription. Beyond these complexities, most mutants obtained with this traditional approach are genetically mosaic, yielding several types of cells with different genetic mutations. Recently, a growing body of studies has utilized commercially available Cas9 protein together with sgRNA and a targeting construct to introduce desired mutations. Here, we report a cloning-free method to target the mouse genome by pronuclear injection of a commercial Cas9 protein:crRNA:tracrRNA:single-strand oligodeoxynucleotide (ssODN) complex into mouse zygotes. As illustration of this method, we report the successful generation of global gene-knockout, single-amino-acid-substituted, as well as floxed mice that can be used for conditional gene-targeting. These models were produced with high efficiency to generate non-mosaic mutant mice with a high germline transmission rate

Comparing Approaches for the Sustainability of Scientific Data Repositories

Sustainable data systems are critical components of the cyberinfrastructure needed to provide long-term stewardship of scientific data, including Earth science data, throughout their entire life cycle. A variety of approaches may help ensure the sustainability of such systems, but these approaches must be able to survive the demands of competing priorities and decreasing budgets over long time periods. Analyzing and comparing various approaches can identify viable aspects of each approach and inform decisions for developing, managing, and supporting the cyberinfrastructure needed to facilitate discovery, access, and analysis of data by future communities of users. A typology of sustainability approaches is proposed, and example use cases are offered for assessing the approaches over time. These examples help illustrate the potential strengths and weaknesses of each approach under various conditions and with regard to different objectives, e.g., open vs. limited access. By applying the results of these analyses to their particular circumstances, systems stakeholders can assess their options for a sustainable systems approach, which may incorporate multiple sustainability options, along with other metrics to ensure the sustainability of the scientific data and information for which they are responsible. In addition, clarifying and comparing sustainability approaches should inform the design of new systems and the improvement of existing systems to meet the needs for long-term stewardship of scientific data, and support education and workforce development efforts needed to ensure that the appropriate scientific and technical skills are available to operate and further develop sustainable cyberinfrastructure

Independent Evaluation of a Scientific Data Center for Compliance with the ISO 16363 Requirements for Audit and Certification of Trustworthy Digital Repositories

Scientific data centers and other digital repositories need to continuously improve so that they can meet the challenge of providing stewardship for the scientific data that are used by scientists, policy-makers, educators and their students, and the general public. As part of its efforts to continuously improve its capabilities and services offered to communities that are interested in using scientific data on human interactions in the environment, SEDAC, the NASA Socioeconomic Data and Applications Center, requested an independent test audit to evaluate its compliance with the draft requirements of ISO 16363:2012, the international standard for Audit and Certification of Trustworthy Digital Repositories. SEDAC has conducted various audits through the years as part of its self-improvement efforts. However, obtaining an independent test audit for compliance with the draft metrics in ISO 16363 offers an opportunity to identify ways in which the scientific data center could im! prove its organization and management, its processes for managing and disseminating data, and its systems and security infrastructure. Similarly, when organizations and auditors are authorized to offer certification of trustworthy digital repositories, SEDAC will be better prepared to apply for certification as a result of having been previously audited by independent evaluators for compliance with the draft ISO 16363 metrics

A piloted simulation of helicopter air combat to investigate effects of variations in selected performance and control response characteristics

A piloted simulation study investigating handling qualities and flight characteristics required for helicopter air to air combat is presented. The Helicopter Air Combat system was used to investigate this role for Army rotorcraft. Experimental variables were the maneuver envelope size (load factor and sideslip), directional axis handling qualities, and pitch and roll control-response type. Over 450 simulated, low altitude, one-on-one engagements were conducted. Results from the experiment indicate that a well damped directional response, low sideforce caused by sideslip, and some effective dihedral are all desirable for weapon system performance, good handling qualities, and low pilot workload. An angular rate command system was favored over the attitude type pitch and roll response for most applications, and an enhanced maneuver envelope size over that of current generation aircraft was found to be advantageous. Pilot technique, background, and experience are additional factors which had a significant effect on performance in the air combat tasks investigated. The implication of these results on design requirements for future helicopters is presented

A Portfolio Approach to a Sustainable Business Model for Scientific Data Stewardship

Examination of sustainable business models is conducted to identify opportunities for ensuring continuing support of scientific data centers and other digital repositories that are responsible for the stewardship of resources to support science and scholarship. Based on a typology of sustainable approaches for scientific data stewardship, a portfolio approach is proposed for repositories that are seeking to improve the sustainability of their business models. Such a diversified approach should not only support current operational services but also reduce the risks to long-term data stewardship