Preventing Premature Death in the M&S Lifecycle: Lessons Learned from Resurrection and Modernization of a Space System Contamination Model

Models and simulations (M&S) are often developed to meet specific needs and unique requirements for a particular situation. Once the M&S is implemented for a specific case and questions are answered, the M&S may go dormant until a similar need arises again at a later time, perhaps months to years later. Possible modification of the M&S may be required, and issues may arise if the M&S is not well documented, captured, or available. This can severely limit the useful life of the M&S and hinder future development or enhancements. This situation occurred with an M&S tool that had been developed to determine the impact to space system performance due to the presence of molecular contaminant films accumulating on key spacecraft surfaces. The challenges and issues encountered when resurrecting, executing, and modernizing the tool will be presented as a case study. To stay ahead of tomorrows challenges, resources to create M&S tools must be utilized efficiently. Lessons learned from this case study will aid M&S developers and users in planning for proper maintenance, transfer, and capture of key M&S tools and knowledge to avoid increased cost, increased development time, and wasted resources for projects relying on M&S

Diet analysis of two data deficient stingray species, the southern stingray (Hypanus americanus) and the Caribbean whiptail ray (Styracura schmardae), with methodological insights into the use of stomach content analysis and stable isotope analysis

The study of animal diet has long been a fundamental area of biological sciences and has developed significantly over the centuries. An understanding of animal diet goes beyond species-specific biology providing insights into interspecific interactions and whole ecosystem functions essential for ecosystem-based management. Anthropogenic activities have caused major declines in marine vertebrate populations many of which are top predators. It is therefore vital to establish an ecological understanding of mesopredators in the oceans who may either mediate or exacerbate the cascading impacts of such declines. Elasmobranch batoids (otherwise referred to as rays) are a diverse, yet highly vulnerable group of mesopredators many of which are considered data deficient and lack comprehensive dietary assessments. Studies that do exist use stomach content analysis (SCA) or stable isotope analysis (SIA) independently of one another. In contrast, the present thesis integrates these two methods. Chapter one aimed to utilize both SCA and SIA techniques to provide the first integrative dietary assessment of the southern stingray (Hypanus americanus), and the first ever quantitative dietary study of the Caribbean whiptail ray (Styracura schmardae), two sympatric and data deficient species. Our results suggested that the diets of both species were similar in structure and composition, though Caribbean whiptail ray diet was dominated by arthropod and annelid prey, while southern stingray diet was dominated by molluscs. The broad variety of taxa identified in the stomachs of both species indicates opportunistic feeding, likely as mesopredators at a trophic level similar to other ray species in their respective families. Our integration of SCA and SIA highlights the advantages of combining the two methods, for example, the higher representation of soft-bodied prey in stable isotope mixed models (SIMM) compared to those of SCA. The focus of Chapter two was the isotopic variances between three metabolically different tissues (blood, white muscle and barb) from both the southern stingray and the Caribbean whiptail ray, highlighting how the use of multiple tissues in diet assessments may give better insight into the temporal variability of diet. This was the first quantitative comparison of SCA and SIA across tissue types in rays, the results of which suggest that method agreement is influenced by tissue type incorporated in SIMM. A limitation of our inferences, however, is the lack of data available on isotopic turnover rates in ray and elasmobranch tissues, thus we recognise the need for further literature and diet manipulation experiments. Nonetheless, the results of the present thesis provide a novel insight into the diets of these two data deficient stingray species and highlight potential avenues for future research which would improve our understanding of these ecologically significant and vulnerable animals

Looking Back 30 Years: AIDS, San Francisco, and How We Learned There and Then

Employing Cultural Historical Activity Theory as a theoretical lens, this study examines the first three years of the AIDS crisis, with the purpose of examining how the San Francisco gay community (SFGC) and the San Francisco medical community (SFMC) entered a cycle of expansive learning while confronting the AIDS crisis

Explorations in social memory - rock art. Landscape and the reuse of place

publishedVersio

Automatic assembly design project 1968/69: report of the control and motivation committee

Methods of control for automatic assembly machines are surveyed. The control requirements of the versatile automatic assembly machine are analysed, and the most practical system is specified and designed in detail

Predicting September sea ice: Ensemble skill of the SEARCH Sea Ice Outlook 2008-2013

Abstract Since 2008, the Study of Environmental Arctic Change Sea Ice Outlook has solicited predictions of September sea-ice extent from the Arctic research community. Individuals and teams employ a variety of modeling, statistical, and heuristic approaches to make these predictions. Viewed as monthly ensembles each with one or two dozen individual predictions, they display a bimodal pattern of success. In years when observed ice extent is near its trend, the median predictions tend to be accurate. In years when the observed extent is anomalous, the median and most individual predictions are less accurate. Statistical analysis suggests that year-to-year variability, rather than methods, dominate the variation in ensemble prediction success. Furthermore, ensemble predictions do not improve as the season evolves. We consider the role of initial ice, atmosphere and ocean conditions, and summer storms and weather in contributing to the challenge of sea-ice prediction. Key Points Analysis of Sea Ice Outlook contributions 2008-2013 shows bimodal success Years when observations depart from trend are hard to predict despite preconditioning Yearly conditions dominate variations in ensemble prediction success

Predicting September sea ice: Ensemble skill of the SEARCH Sea Ice Outlook 2008–2013

Since 2008, the Study of Environmental Arctic Change Sea Ice Outlook has solicited predictions of September sea-ice extent from the Arctic research community. Individuals and teams employ a variety of modeling, statistical, and heuristic approaches to make these predictions. Viewed as monthly ensembles each with one or two dozen individual predictions, they display a bimodal pattern of success. In years when observed ice extent is near its trend, the median predictions tend to be accurate. In years when the observed extent is anomalous, the median and most individual predictions are less accurate. Statistical analysis suggests that year-to-year variability, rather than methods, dominate the variation in ensemble prediction success. Furthermore, ensemble predictions do not improve as the season evolves. We consider the role of initial ice, atmosphere and ocean conditions, and summer storms and weather in contributing to the challenge of sea-ice prediction

Emotional connections with the past:Exploring engagement with historical images from an online museum collection

Many museums are taking steps to open their collections to the public online. The motivations for this are varied but raise new questions about how people make connections with the historical past. On the one hand, visitors are presented with forms of artefact other than the tangible content of a physical museum exhibition. On the other, the digitisation of the past brings with it the potential to explore and see the connectedness of museum items that support new forms of sense making for visitors. The idea of a “visitor”, in this context, is similarly taking on a new significance to museums, beyond that of the paying observer, referring to depth and range of knowledge, interests and degrees of engagement with the past.</p

The reversibility of sea ice loss in a state-of-the-art climate model

Rapid Arctic sea ice retreat has fueled speculation about the possibility of threshold (or ‘tipping point’) behavior and irreversible loss of the sea ice cover. We test sea ice reversibility within a state-of-the-art atmosphere–ocean global climate model by increasing atmospheric carbon dioxide until the Arctic Ocean becomes ice-free throughout the year and subsequently decreasing it until the initial ice cover returns. Evidence for irreversibility in the form of hysteresis outside the envelope of natural variability is explored for the loss of summer and winter ice in both hemispheres. We find no evidence of irreversibility or multiple ice-cover states over the full range of simulated sea ice conditions between the modern climate and that with an annually ice-free Arctic Ocean. Summer sea ice area recovers as hemispheric temperature cools along a trajectory that is indistinguishable from the trajectory of summer sea ice loss, while the recovery of winter ice area appears to be slowed due to the long response times of the ocean near the modern winter ice edge. The results are discussed in the context of previous studies that assess the plausibility of sea ice tipping points by other methods. The findings serve as evidence against the existence of threshold behavior in the summer or winter ice cover in either hemisphere