The long-term fate of permafrost peatlands under rapid climate warming

Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms.

Producing and Governing Community (Through) Resilience

This article argues that the UK government’s Community Resilience programme is less about responding to disasters and more a matter of producing community and governing its behaviour. The passing over of responsibility to local volunteers and organisations is not only about empowerment, but forming identities and relationships that can be more efficiently managed and directed. However, this attempt is hamstrung by its basis in a nostalgic, romantic view of community and the effacement of poverty and inequality as central to the vulnerability/resilience binary. The effect may be a more intense government of communities rather than their empowerment through resilience.

Inside the tent: Community and government in refugee camps

Refugee camps are increasingly managed through a liberal rationality of government similar to that of many industrialized societies, with security mechanisms being used to optimize the life of particular refugee populations. This governmentality has encompassed programmes introduced by the United Nations High Commissioner for Refugees (UNHCR) and various non-governmental organizations (NGOs) to build and empower communities through the spatial technology of the camp. The present article argues that such attempts to ‘govern through community’ have been too easily dismissed or ignored. It therefore examines how such programmes work to produce, manage and conduct refugees through the use of a highly instrumentalized understanding of community in the spatial and statistical management of displaced people in camps. However, community is always both more and less than what is claimed of it, and therefore undermines attempts to use it as a governing tactic. By shifting to a more ontological understanding of community as unavoidable coexistence, inspired by Jean-Luc Nancy, we can see how the scripting of and government through community in camps is continually exceeded, redirected and resisted. Ethnographies of specific camps in Africa and the Middle East enable us both to see how the necessary sociality of being resists its own instrumentalization and to view the camp as a spatial security technology. Such resistance does not necessarily lead to greater security, but it redirects our attention to how community is used to conduct the behaviour of refugees, while also producing counter-conducts that offer greater agency, meaning and mobility to those displaced in camps.

Ethics, power and space: International hospitality beyond Derrida

This article argues for the importance of hospitality in discussions of international ethics, suggesting that, while Jacques Derrida’s thought on the concept ought to be central, we also need to go beyond it. In particular, Derrida’s focus on the threshold moment of sovereign decision has the effect of reinforcing International Relations’ focus on the state as the only ethical actor and space. In contrast, this article suggests that we think of hospitality as a spatial relation with affective dimensions and a practice that continues once the guest crosses the threshold of the home. Conceived as such, hospitality reveals a constitutive relation between ethics, power and space, which directs us to the way hospitality produces international spaces and manages them through various tactics seeking to contain the resistant guest. This argument is illustrated through an examination of perhaps the most urgent of contemporary international ethical spaces: the refugee camp.

3D FEM simulation of helical milling hole process for titanium alloy Ti-6Al-4V

As an emerging hole-machining methodology, helical milling process has become increasingly popular in aeromaterials manufacturing research, especially in areas of aircraft structural parts, dies, and molds manufacturing. Helical milling process is highly demanding due to its complex tool geometry and the progressive material failure on the workpiece. This paper outlines the development of a 3D finite element model for helical milling hole of titanium alloy Ti-6Al-4V using commercial FE code ABAQUS/Explicit. The proposed model simulates the helical milling hole process by taking into account the damage initiation and evolution in the workpiece material. A contact model at the interface between end-mill bit and workpiece has been established and the process parameters specified. Furthermore, a simulation procedure is proposed to simulate different cutting processes with the same failure parameters. With this finite element model, a series of FEAs for machined titanium alloy have been carried out and results compared with laboratory experimental data. The effects of machining parameters on helical milling have been elucidated, and the capability and advantage of FE simulation on helical milling process have been well presented.

Analysis of the early-time optical spectra of SN 2011fe in M101

The nearby Type Ia supernova SN 2011fe in M101 (cz=241 km s^-1) provides a unique opportunity to study the early evolution of a "normal" Type Ia supernova, its compositional structure, and its elusive progenitor system. We present 18 high signal-to-noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, showing overlapping regions of burned and unburned material between ejection velocities of 10,000 and 16,000 km s^-1. This supports the notion that incomplete burning, in addition to progenitor scenarios, is a relevant source of spectroscopic diversity among SNe Ia. The observed evolution of the highly Doppler-shifted O I 7774 absorption features detected within five days post-explosion indicate the presence of O I with expansion velocities from 11,500 to 21,000 km s^-1. The fact that some O I is present above C II suggests that SN 2011fe may have had an appreciable amount of unburned oxygen within the outer layers of the ejecta.