3,812,108 research outputs found
Evolution from a hinge actuator mechanism to an antenna deployment mechanism for use on the European large communications satellite (L-SAT/OLYMPUS)
The evolution of an Antenna Deployment Mechanism (ADM) from a Hinge Actuator Mechanism (HAM) is described as it pertains to the deployment of large satellite antennas. Design analysis and mechanical tests are examined in detail
Benthic and hyporheic invertebrate community responses to seasonal flow recession in a groundwater-dominated stream
Natural hydrological variability in lotic ecosystems can include prolonged periods of flow recession. A reduction in discharge is accompanied by abiotic changes in benthic and hyporheic habitats, often including reductions in s habitat availability. Whilst the benthic invertebrate community response to low flows is well documented, little research has considered how the composition of the community within the hyporheic zone is affected. We examined benthic and hyporheic invertebrate community composition during flow recession in a temperate karst stream, at sites with contrasting historic flow permanence regimes. Changes in the benthic invertebrate community composition primarily reflected changes in habitat availability associated with discharge variability; in particular, the population density of the dominant amphipod, Gammarus pulex, increased as the area of submerged benthic sediments declined. Concurrent significant increase in the hyporheic abundance of G. pulex, and moderate increase in the proportion of the total G. pulex population inhabiting the hyporheic zone were recorded. It is postulated that G. pulex migrated into the hyporheic zone to reduce exposure to intensifying biological interactions in the benthic sediments. Increase in the hyporheic abundance of G. pulex was particularly pronounced at sites with historic intermittent flow, which could be attributed to downwelling stream water dominating vertical hydrologic exchange. The increase in G. pulex abundance reduced community diversity in the benthic sediments, but had no apparent detrimental effects on the hyporheic invertebrate assemblages
Who speaks for the future of Earth? How critical social science can extend the conversation on the Anthropocene
This paper asks how the social sciences can engage with the idea of the Anthropocene in productive ways. In response to this question we outline an interpretative research agenda that allows critical engagement with the Anthropocene as a socially and culturally bounded object with many possible meanings and political trajectories. In order to facilitate the kind of political mobilization required to meet the complex environmental challenges of our times, we argue that the social sciences should refrain from adjusting to standardized research agendas and templates. A more urgent analytical challenge lies in exposing, challenging and extending the ontological assumptions that inform how we make sense of and respond to a rapidly changing environment. By cultivating environmental research that opens up multiple interpretations of the Anthropocene, the social sciences can help to extend the realm of the possible for environmental politics
Modelling abrupt glacial North Atlantic freshening: Rates of change and their implications for Heinrich events
The abrupt delivery of large amounts of freshwater to the North Atlantic in the form of water or icebergs has been thought to lead to significant climate change, including abrupt slowing of the Atlantic Ocean meridional overturning circulation. In this paper we examine intermediate complexity coupled modelling evidence to estimate the rates of change, and recovery, in oceanic climate that would be expected for such events occurring during glacial times from likely sources around the North Atlantic and Arctic periphery. We show that rates of climate change are slower for events with a European or Arctic origin. Palaeoceanographic data are presented to consider, through the model results, the origin and likely strength of major ice-rafting, or Heinrich, events during the last glacial period. We suggest that Heinrich events H1-H3 are likely to have had a significant contribution from an Arctic source as well as Hudson Strait, leading to the observed climate change. In the case of H1 and H2, we hypothesise that this secondary input is from a Laurentide Arctic source, but the dominant iceberg release for H3 is hypothesised to derive from the northern Fennoscandian Ice Sheet, rather than Hudson Strait. Earlier Heinrich events are suggested to be predominantly Hudson Strait in origin, with H6 having the lowest climate impact, and hence iceberg flux, but H4 having a climate signal of geographically variable length. We hypothesise that this is linked to a combination of climate-affecting events occurring around the globe at this time, and not just of Laurentide origin. (C) 2010 Elsevier B.V. All rights reserved
Unfamiliar families and disturbing climate futures
Ecomaternalism remains the dominant narrative concerning the role of families in climate politics. The centrality of ecomaternalist narratives to intersectional constructions of race, gender, heteronormativity, and nature means that interrogating and disrupting these dominant representations of families is a crucial task of ecofeminist, postcolonial, and queer political theory. This article explores other ways to narrate familial politics that might challenge rather than reproduce dominant power relations. Examining three Africanfuturist short stories by Nnedi Okorafor (âSpider the Artistâ), Tlotlo Tsamaase (âVirtual Snapshotsâ), and Terh Agbedeh (âMango Republicâ), set in Nigeria and Botswana, I argue that they draw our attention to transformations within cyborg, digitized, and utopian families and social structures, as well as the potential for violence within the heteronormative patriarchal family. They narrate alternative discourses about families in crisis, families as threat, and families as ruination that are rarely articulated in climate politics. In these stories, the family is not the solution to climate politics, but a social relation that will (and should) change as the climatic and social context changes
Governmentality at the limits of the international: African politics and Foucauldian theory
AbstractThe ability of International Relations theory to âtravel wellâ to other parts of the world has become one of the central questions within the discipline. This article argues that a Foucauldian-derived âanalytics of governmentâ framework has particular advantages in overcoming some of the difficulties IR theory has faced abroad. These advantages include a methodological focus on specific practices of power at their point of application; attention to similarities between practices of power that cut across perceived binaries such as the domestic and international, and public and private; and an illumination of the ways in which practices of freedom are combined and interrelate with forms of coercion and violence. This argument is illustrated in the context of debates about the applicability of Foucauldian theory to African politics, through examples drawn from Bayart's work on globalisation, the power of development partnerships, and violence and civil war. It argues that deploying governmentality as an analytical framework, rather than seeing it as a specifically neoliberal form of power relation, can not only facilitate the application of IR theory outside Europe and North America but can also help develop a broader perspective on genuinely world politics.</jats:p
Summit theatre: Exemplary governmentality and environmental diplomacy in Johannesburg and Copenhagen
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