Among the longest Antarctic biological time series is that of Adélie penguin Pygoscelis adeliae population size at Cape Royds, 1955 to the present. Demographic trends over the 66 years fall into five periods: 1) decrease then recovery due to control of tourism from McMurdo Station/Scott Base; 2) further increase responding to the removal of > 20 000 trophically competing Antarctic minke whales Balaenoptera bonaerensis from the colony's wintering area; 3) stabilization but not decrease upon the ban of whaling in 1982, and whale recovery, owing to increased winds facilitating McMurdo Sound Polynya presence (easier ocean access during nesting); 4) decrease in 2001–2005 when two mega-icebergs, B15A/C16, opposed the wind effect by increasing sea-ice cover, thus limiting ocean access; and 5) after iceberg departure, minimal recovery due to the increased velocity of the wind-generated Ross Gyre reducing penguin breeding probability. A multivariant model using 1998–2018 data confirmed the roles of gyre speed (negative) and open water (positive) in colony growth. Additional negative influence came from high nest predation by south polar skuas Stercorarius maccormicki, reducing chick production, as well as perhaps increased trophic competition from nearby Weddell seals Leptonychotes weddellii. Clearly, long time series increase our understanding of penguin population dynamics responding to a complexity of factors.

In the 19th century, sealing vessels visited the South Shetland Islands to exploit animal resources for the global skin and oil markets. The captains or mates of these vessels were responsible for keeping a logbook in which they recorded daily observations of weather conditions, hunting activities, etc. Despite the value of these documents as a source of information, archaeologists studying Antarctic sealing have not always relied on them. This paper examines the potential of logbooks for providing information that is relevant to the archaeological study of sealing in the South Shetland Islands. In particular, it discusses how documentary analysis of exploitation strategies can provide insight into the dynamics that influenced the configuration of sealers’ sites. To this end, we propose a methodology for investigating exploitation strategies, taking into account several archaeologically sensitive variables, including the number, location and duration of landings, as well as the activities carried out during these events. We have taken four logbooks dating from the early and late 19th century – specifically those of the Aurora (1820–1821), the Huron (1820–1822), the Thomas Hunt (1873–1874) and the Sarah W. Hunt (1887–1888) – as case studies to test the proposed methodology.

Approximately five centuries of the involvement of Portugal in Antarctic regions is described. Discoveries, the sealing and whaling industries, and modern developments are discussed.

International environmental non-governmental organizations (IENGOs) have a long and checkered history of involvement and impact in, and on, the North. Using the example of Greenpeace, arguably one of the most stigmatized IENGOs in the North American North, this paper explores the questions: why are IENGOs stigmatized in the North American North and how might they overcome their stigma with local audiences? It outlines the role of moral legitimacy in stigmatization and overcoming stigma, and the challenges of (re)establishing moral legitimacy with a stigmatizing audience, in this case, Inuit in Northern Canada and Greenland.

The aim of this study was to investigate if load cycling affects interfacial integrity of glass ionomer cements bonded to sound- or caries-affected dentin. A conventional glass ionomer, Ketac Bond, and a resin-modified glass ionomer (Vitrebond Plus), were applied to dentin. Half of the specimens were load cycled. The interfaces were submitted to dye-assisted confocal microscopy evaluation. The unloaded specimens of sound and carious dentin were deficiently hybridized when Ketac Bond was used. Ketac Bond samples showed an absorption layer and an adhesive layer that were scarcely affected by fluorescein penetration (nanoleakage), in sound dentin. Nevertheless, a higher degree of micropermeability was found in carious dentin. In Ketac Bond specimens, load cycling improves the sealing capability and remineralization at the cement–dentin interface as porosity and nanoleakage was reduced. In contrast, samples treated with Vitrebond Plus exhibited a Rhodamine B-labeled absorption layer with scarce nanoleakage in both sound and carious unloaded dentin. The adhesive layer was affected by dye sorption throughout the porous cement–dentin interface. Samples treated with Vitrebond Plus had significant increases in nanoleakage and cement–dye sorption after load cycling. Within the limitations of an in vitro study, it is expected that conventional glass ionomers will provide major clinical efficacy when applied to carious-affected or sound dentin.

Man's activities have impacted on the Southern Ocean ecosystem for more than 200 years. The exploitation of Southern Ocean resources has followed the same pattern as in other parts of the World Ocean with exploitation starting at the highest trophic levels when seals and whales were taken in the 19th and 20th centuries. After serious over-exploitation of these groups attention moved down the food web to begin exploitation of fish and krill from the late 1960s onwards. The establishment of international management regimes for whales (International Whaling Convention) in 1948 and the remaining marine resources (Convention for the Conservation of Antarctic Marine Living Resources) in 1982 were based on different perceptions of management, the former only considering management by species whilst the latter adopted management at an ecosystem level. These fundamentally different approaches, together with major political interference, have resulted in very different outcomes for management. The Scientific Committee of the IWC developed a sustainable management system, the Revised Management Procedure, in the first half of the 1990s which, however, is still awaiting inclusion into an overall management regime, the Revised Management Scheme, and its acceptance by the Commission. The IWC is now paralysed by political agendas that have nothing to do with scientific management. In contrast, after an early period of slow progress, CCAMLR has improved its performance substantially from the beginning of the 1990s onwards and is now hailed worldwide for its ecosystem approach to sustainable management.

Le fonctionnement optimal des joints d'étanchéité à faces radiales impose que les faces de frottement soient séparées par un film lubrifiant pour éviter l'usure, mais celui-ci doit être aussi mince que possible pour limiter la fuite. Ce compromis nécessite l'équilibrage précis des forces exercées sur l'anneau flottant du joint. Cet équilibre est principalement contrôlé par la déformation thermo-élastique des faces qui est de l'ordre de grandeur de l'épaisseur du film lubrifiant (quelques micromètres). Il est donc important de modéliser le comportement thermoélastohydrodynamique (TEHD) du joint en particulier pendant les périodes transitoires durant laquelle des instabilités peuvent survenir. Le modèle étudié comporte deux anneaux alignés ayant un degré de liberté axial. Les faces sont très légèrement coniques. La température dans les anneaux ne varie que dans la direction axiale. La vitesse de rotation du rotor suit une loi de démarrage exponentielle. La vitesse et la pression dans le film lubrifiant sont obtenues par la résolution analytique de l'équation de Reynolds. Le champ de température unidimensionnel dans les anneaux est déterminé par l'équation de la chaleur. Cette équation est résolue numériquement, par différences finies, au moyen d'une méthode implicite d'intégration. La déformée des faces est établie analytiquement en fonction de la variation axiale de la température dans les anneaux. À chaque pas de temps l'équation de l'équilibre axial permet de déterminer la distance des centres des faces. Les résultats d'une étude paramétrique sont ensuite présentés.