The Influence of Dowel-Bearing Strength in Designing Timber Pegged Timber Joints

ABSTRACT

The employment of timber pegs in timber structure joints is a widespread technology in the field of timber frame building in the United States, where the Timber Frame Engineering Council has published a special Standard to supplement the National Design Specification for Wood Construction. The authors have been studying the possibility of supplementing the Eurocode 5 design formulas, thought for timber joints with metal connectors, with specifications needed for a reliable design when employing timber pegs. The field of application envisaged is that of restoring timber structures and results obtained until now are quite encouraging. In this step of the research, more attention has been paid to deformation process: fir and chestnut samples have been tested to determine their dowel-bearing behavior with steel and ash timber peg while double-shear plane joints made of the same wood species, and fastened with steel as well as timber pegs, have been analyzed.     

Food for all: An agent-based model to explore the emergence and implications of cooperation for food storage

Abstract

A consistent access to food is paramount for humans at individual and group level. Besides providing the basic nutritional needs, access to food defines social structures and has stimulated innovation in food procurement, processing and storage. We focus on the social aspects of food storage, namely the role of cooperation for the emergence and maintenance of common stocks. Cooperative food stocks are examined here as a type of common-pool resource, where appropriators must cooperate to avoid shortage (i.e. the tragedy of commons). ‘Food for all’ is an agent-based model in which agents face the social dilemma of whether or not to store in a cooperative stock, adapting their strategies through a simple reinforcement learning mechanism. The model provides insights on the evolution of cooperation in terms of storage efficiency and considering the presence of social norms that regulate reciprocity. For cooperative food storage to emerge and be maintained, a significant dependency on the stored food and some degree of external pressure are needed. In fact, cooperative food storage emerges as the best performing strategy when facing environmental stress. Likewise, an intermediate control over reciprocity favours cooperation for food storage, suggesting that concepts of closed reciprocity are precursors to cooperative stocks, while excess control over reciprocity is detrimental for such institution.     

Chronostratigraphy of an Eroding Complex Atlantic Round House,Baile Sear,Scotland

A high-resolution chronostratigraphy has been established for an eroding Atlantic round house at Sloc Sàbhaidh (North Uist, Scotland), combining detailed OSL profiling and dating of sediments encompassing the main bracketing events associated with the monument, radiocarbon AMS dates on bone recovered from excavated features and fills within it, and TL dates on pottery and burnt clay. Concordant OSL and radiocarbon evidence place construction of the wheelhouse in the first to second centuries AD, contemporary with dates from the primary occupation. Beneath the wheelhouse, clay deposits containing burnt material, attest to cultural activity in vicinity to the monument in the preceding second to first centuries BC. At a later date, the southern wall collapsed, was rebuilt, and the interior spaces to the monument re-structured. The chronology for the later horizons identified from the sediment luminescence dates extends to the second half of the first millennium AD, which goes beyond the range of the radiocarbon dates obtained. The data from ceramics encompass both periods. The juxtaposition of the dating evidence is discussed relative to short and longer chronologies for this Iron Age monument. Corollaries of this research are the implications that based on the long chronology, some of the ecofacts (bone) appear to be residual, and that the temporal duration of Hebridean Coarse Ware may extend into the second half of the first millennium AD.     

Stable Isotopes,Chronology, and Bayesian Models for the Viking Archaeology of North-East Iceland

This paper reviews the results of a long-term research project that used stable isotope analyses (δ¹³C, δ¹⁵N, δ³⁴S) and Bayesian mixing models to better model the chronology for a presumed Viking Age cemetery at Hofstaðir, near Lake Mývatn in north-east Iceland. δ¹³C and radiocarbon dating indicated that many of the individuals consumed a large amount of marine protein, which results in a marine reservoir effect (MRE), making ages older than expected. In addition to the MRE, geological activity in the region has the potential to introduce massive quantities of radioactive ‘dead’ carbon into the freshwater system, resulting in a very large freshwater reservoir effect (FRE) that can offset radiocarbon ages on the order of a few thousand years. The radiocarbon dates of organisms that derive an unknown proportion of their carbon from both marine and freshwater reservoirs are extremely difficult to ‘correct’, or, more appropriately, model. The research not only highlights the complexities of dealing with multiple reservoirs, but also how important it is to develop models that are temporally and geographically relevant to the site under study. Finally, it shows how this data can be used to inform the development of chronological models for refining the dating for archaeological activity.     

"A wealth of historical interest": the medical artifact collection at the University of Western Ontario

Along with a teaching collection, the Faculty of Medicine at the University of Western Ontario, London, Canada, began accepting medical artifacts for a historical museum in the early 1920s, although it never developed into more than an unofficial collection until the 1970s, when it was transformed into the Medical Museum and Archives at the University Hospital. In the 1990s, the artifacts were dispersed among several local institutions. The remaining objects at the university have been now reorganized as the Medical Artifact Collection. While these objects were once used to educate students about the practice and philosophy of medicine, they are now used to teach students about local, medical, Canadian and public history.     

Active learning through online quizzes: better learning and less (busy) work

Active learning is increasingly promoted within institutions of higher education to assist students develop higher order thinking and link knowledge to meaning. In this paper, the authors evaluate the use of weekly online quizzes based on prescribed preparatory material as a tool to incentivize preparatory reading in order to enable and encourage active learning. The study is based on mixed data sources, including three years of student-evaluation data, to understand student perceptions of the role and value of online quizzes. The study shows a high level of student engagement with the quizzes and positive assessment of their role in encouraging the completion of prescribed reading. Online quizzes were found to be an effective mechanism for incentivizing student completion of preparatory work, enhancing active learning (such as through in-class discussions), and were relatively time efficient from the perspective of the educator.     

Religious Transformations in the Middle Ages: Towards a New Archaeological Agenda

UNDERSTANDING RELIGIOUS CHANGE between the collapse of the Roman Empire and the Reformation forms one of the cornerstones of medieval archaeology, but has been riven by period, denominational, and geographical divisions. This paper lays the groundwork for a fundamental rethink of archaeological approaches to medieval religions, by adopting an holistic framework that places Christian, pagan, Islamic and Jewish case studies of religious transformation in a long-term, cross-cultural perspective. Focused around the analytical themes of ‘hybridity and resilience’ and ‘tempo and trajectories’, our approach shifts attention away from the singularities of national narratives of religious conversion, towards a deeper understanding of how religious beliefs, practices and identity were renegotiated by medieval people in their daily lives.     

The role of accredited zoos in the recovery process for species at risk in Canada

Zoos and aquariums are responding to the worldwide biodiversity crisis through major conservation initiatives like captive breeding for assurance populations and reintroduction programs. These institutions also fundraise, offer education programs, and provide critical research on biodiversity. Through a case study inside three accredited Canadian zoos, this paper illustrates that zoos and their staff members are being incorporated into many official species‐at‐risk recovery efforts on provincial, federal, and international levels. Specifically, the zoos studied are involved in every stage of the recovery process, from providing valuable research and habitat analyses, to captive breeding animals for reintroduction, to writing recovery strategies and creating recovery policy for multiple jurisdictional levels. Zoo staff indicate that zoos are uniquely suited to conservation because zoos have space, expertise, apolitical status, and the ability to connect with the public. Overall, the paper suggests that zoos can significantly contribute to species‐at‐risk protection and recovery in Canada and beyond.