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• Use of fire enables surface dwelling humans to access the Earth's subsurface. • Early human fire use linked to evolution in tectonically active landscapes. • Mineral extraction and chambered fire underpin political power in ancient city-states. • Gunpowder and explosive weapons crucial to expansion of early modern empires. • Climate change calls for new ways of using fire to negotiate the subsurface. The geopolitical - or more specifically pyropolitical – crisis triggered by combusting fossilized hydrocarbons can be viewed in the context of a much longer human history of utilising fire as a means of traversing and utilising the Earth's subsurface. The paper develops a conceptual framework to show how the developing fire-subsurface nexus advances through a succession of different human enfoldings or 'involutions' of fire that serve to intensify its force. This is explored at three critical junctures: the earliest hominin uses of fire in the geologically active landscape of the Great Rift Valley, the chambering of fire by ancient artisans and the material and political significance of its products in emergent city-states, and the role of explosive weapons in gunpowder empires. Finally, the paper circles back on the question of how revisiting the longue durée of human fire-subsurface entanglements might help us conceive of alternative pyropolitical realities. [ABSTRACT FROM AUTHOR]

New techniques in the simulation of nature are giving computer-generated environments a more organic appearance. In particular, developments in 'artificial life' modelling promise to populate future cyberspaces with diverse, autonomous beings. This can be viewed as an impending estrangement from 'real' nature, but we might better conceive of virtual natures as a culmination of a lengthy Western tradition of representing the natural world in increasingly exuberant two- and three-dimensional forms. It is suggested that the ecology movement is implicated in the ascendance of simulated nature, and must come to terms with the 'reality' of mediation, rather than privileging the notion of unmediated, 'primordial' nature. (Reprinted by permission of the publisher.)

Highlights • The percent of flexure's moving mass is in the range of 29–31%. • Spiral length and diameter are the first two most significant design parameters. • Thickness and number of arms take the third and fourth places of significance. • Modifications of spiral ends can reduce the maximum stress by 20%. • The max achievable resonant frequency and the max stress are linearly proportional. Abstract A method for optimization of a high-stroke, high-frequency flexural bearing was completed. The main goal was to design a flexural bearing system as the energy restoration component of a one kW free piston linear engine alternator (LEA) operating at 90 Hz and maximum targeted displacement of 22 mm. Defined electricity output of 1 kW, with more than 30% efficiency, required engine operation under high speed and high stroke conditions. Under such challenging stroke and frequency requirements, a method of design was required to select between a wide range of parameters in flexural bearing design. A parametric CAD model was prepared and used in the optimization package of a finite element analysis (FEA) software. Four main parameters of flexural bearing geometry were identified and included the outer diameter, thickness, number of arms, and sweep angle of spiral cuts. Other design parameters including spiral gap width, shape factor and spiral start points angle were shown to be less important compared to these four main parameters in primary design and were examined separately. A neural network algorithm was used to investigate the interactions and effects of design parameters. The sensitivity of each parameter on output criteria such as maximum stress and natural frequency was examined and design charts developed. Methods for further modification of the spiral curve at end points were introduced to reduce the maximum stress level by up to 20%. Several steel alloys and a titanium-based alloy were identified as proper material candidates for high cycle applications and the final designed spring was manufactured and tested to validate the FEA results of axial stiffness and strain level throughout the flexure arms. The percent of the flexure's moving mass was estimated to be 29% with FEA analysis and compared well with the experimental value of 31%. The stress/strain results of the FEA analysis matched with the experimental results – within ±5%. [ABSTRACT FROM AUTHOR]

Abstract: How might geographers respond ‘generously’ to a disaster on the scale of the Indian Ocean tsunami? Critical geographers and other left intellectuals have chosen to stress the way pre-existing social forces conditioned human vulnerability, and have implied that ordinary people ‘here’ were implicated in the suffering of others ‘there’ through their positioning in chains of causality. Critics have also sought to expose the bias, unjustness and inappropriateness of post-tsunami patterns of donation and programs of aid and recovery. A supplement to this mode of critique is offered in the form of a view of disasters and human vulnerability that hinges on the idea of the self as ‘radically passive’: that is, as inherently receptive to both the stimuli that cause suffering, and to the demands of others who are suffering. All forms of thought – including geography and disaster studies should themselves be seen as ‘vulnerable’ and responsive to the impact to disasters. The idea that every ‘self’ bears the trace of past disasters – and past gifts of others – forms the basis of a vision of bodies and communities as always already ‘fractured’ by disaster – in ways which resist being ‘brought to light’. This offers a way of integrating human and physical geographies through a shared acknowledgement of what is unknowable and absent. It is also suggestive that gratitude might be an appropriate response to a sense of indebtedness to others – for who we are, as much as for what we have done. [Copyright &y& Elsevier]

The Wash, in eastern England, supports internationally important populations of 11 species of shorebird. A major commercial shellfishery provides potential conflict between fishermen and nature conservation interests. During the 1990s, high fishing mortality and low recruitment substantially reduced the stocks of cockle (Cerastoderma edule) and mussel (Mytilus edulis). Population models, constructed from estimates of survival and recruitment, indicated that declines in the availability of cockles and mussels were associated with changes in oystercatcher (Haemotopus ostralegus) survival between 1970 and 1998, including three periods of mass mortality, and also the recruitment of juvenile birds to both oystercatcher and knot (Calidris canutus) populations. Emigration of knot may also have taken place. Cockle recruitment was dependent on climatic conditions, whereas mussel populations tended to be stable. The decline in mussel stocks, due to over-fishing, increased the vulnerability of the oystercatcher population to mass-mortality episodes in poor cockle years. The key to preventing major oystercatcher kills in future is to ensure sufficient mussels are available in poor cockle years. Recent cultivation of mussels in inter-tidal areas has been beneficial and is an important management tool for maintaining bird populations. [Copyright &y& Elsevier]

Highlights • LPDI increased indicated efficiency to 28–30% dependent on engine speed. • Start of direct injection at 180 CA BTDC minimized fuel loss. • LPDI met current emissions regulations, cutting fuel slip by over a factor of 2. • Higher volumetric efficiency led to increased power density. • LPDI augmented energy distribution, to capitalize on heat recovery for CHP. Abstract This paper examines methods to simultaneously improve efficiency and reduce emissions from a 34 cc air-cooled two-stroke engine configured to operate on natural gas, using tuned intake plus exhaust resonators designed from Helmholtz resonance theory to promote effective scavenging. The engine was developed for novel application in a small, free piston engine for decentralized power generation. Operation occurred at wide-open-throttle at a speed of 5400 RPM for both port injection (PI) and low-pressure direct injection (LPDI). In both cases, the electronic ignition timing was adjusted for maximum brake torque, while the fuel was adjusted such that both rich and lean combustion were examined. The LPDI engine was then operated over a variety of engine speeds. An energy balance was completed for both PI and LPDI operation, which quantified all energy pathways, as engine operating regimes changed. Results showed that exhaust chemical energy (ECE) for LPDI was reduced significantly when compared to PI, mostly due to less fuel slip. The fuel slip rate ranged from 35 to 40% for PI operation while it was in the range of 6–20% for LPDI operation. However, mixture stratification with LPDI operation increased carbon monoxide emissions. The start-of-injection (SOI) was also examined, targeting a SOI to provide the highest trapping efficiency and most stable combustion. For LPDI operation, trapping efficiency, which is function of engine speed, showed significant effects on overall efficiency and fuel slip. Air volumetric efficiency increased due to the absence of gaseous fuel within the intake manifold. It was shown that, relative to PI, the overall engine indicated efficiency increased by 90% to a maximum indicated efficiency of 30% for LPDI operation with a SOI of 180 CAD BTDC. [ABSTRACT FROM AUTHOR]

We collected data focusing on in-use emissions and efficiency of engines servicing the unconventional well development industry to elucidate real world impacts from current and newly applied engine technologies. The engines examined during the campaigns were diesel only (DO) and dual fuel (DF) diesel/natural gas, compression-ignition (CI) engines and dedicated natural gas, spark-ignition (SI) engines. These included two CI drilling engines outfitted with two different DF kits, two SI drilling engines, and two CI well stimulation engines. Our data were gathered under the load and speed requirements in the field, and the engines were not under our direct control. Greenhouse gas (GHG) emissions were measured from all engines and fueling types and included both exhaust and crankcase emissions. Fuel consumption and engine data were collected to determine fuel efficiency. During steady-state operation, fuel efficiency was 38%, 26%, and 20% for DO, DF, and SI engines, respectively. The loss of efficiency during DF operation was due in part to uncombusted methane (CH 4 ) slip in the exhaust, which accounted for 18% of the fuel supplied. GHG emissions (carbon dioxide and CH 4 ) from CI engines were 2.25 times higher during DF compared to DO operation. During DF operation, substitution ratio varied depending on engine load and DF kit, ranging from 9% to 74%. GHG emissions from the SI engines were 1.33 times higher than DO due to lower efficiencies of throttled and rich operation as compared to unthrottled and lean operation for CI engines. [ABSTRACT FROM AUTHOR]

The marine environment is increasingly pressured from human activities, such as offshore renewable energy developments. Offshore wind farms may pose direct risks to seabirds at protected breeding sites. However, changes in food availability may influence foraging behaviour and habitat use during the breeding season or between years. Consequently, seabird–wind farm interactions, and risks posed to populations, may vary over longer time scales, but this has seldom been quantified. We used GPS-telemetry to study the movements of 25 lesser black-backed gulls from the Alde–Ore Special Protection Area (SPA), UK between 2010 and 2012, while birds were associated with their breeding colony. Variation in movements away from the colony, offshore, and in operational, consented and proposed Offshore Wind Farm Areas (“OWFAs”) was investigated: (1) between years and (2) across the breeding season, addressing: (3) sex-specific, (4) individual and (5) diurnal/nocturnal differences. The extent of overlaps with OWFAs varied between years, being greatest in 2010 (7/10 birds showing connectivity; area overlap: 6.2 ± 7.1%; time budget overlap: 4.6 ± 6.2%) and least in 2012. Marine habitats close to the colony were used before breeding. Birds spent little time offshore as incubation commenced, but offshore usage again peaked during the early chick-rearing period, corresponding with use of OWFAs. Individuals differed in their seasonal interactions with OWFAs between years, and males used OWFAs significantly more than females later in the breeding season. This study demonstrates the importance of tracking animals over longer periods, without which impact assessments may incorrectly estimate the magnitude of risks posed to protected populations. [ABSTRACT FROM AUTHOR]

Abstract: A multi-phase instrument comparison study was conducted on two different diesel engines on a dynamometer to compare commonly used particulate matter (PM) measurement techniques while sampling the same diesel exhaust aerosol and to evaluate inter- and intra-method variability. Included in this evaluation were a Tapered Element Oscillating Microbalance (TEOM), three Scanning Mobility Particle Sizers (SMPSs), a Condensation Particle Counter (CPC), a TSI DustTrak, a MET-One E-BAM, and two Electrical Low Pressure Impactors (ELPIs) as well as two types of time-integrated filter samplers. Of the five on-line analyzers evaluated for PM mass concentration, the TEOM was shown to have the best overall correlation to the gravimetric filter method. For measuring concentration by particle number, the two ELPIs and the Model 3936L25 SMPS provided generally comparable results during both test phases (data for the stand-alone CPC were invalidated). With respect to measuring particle size distribution (PSD) by gravimetric analysis, the ELPIs were not found to be useful for a variety of reasons whereas for differential number distribution, the SMPSs and ELPIs provided generally comparable results. [Copyright &y& Elsevier]

The implementation of a comprehensive heavy-duty vehicle (HDV) Inspection and Maintenance (I/M) program could be a critical element in ensuring the emission control effectiveness of diesel HDVs over their full useful life. An on-board diagnostics (OBD)-based I/M program could be a cost-effective emission reduction program for diesel HDVs. Forty-five vehicles equipped with selective catalytic reduction (SCR) with either the check-engine-light-on or malfunction-indicator-light (MIL)-on, or both, and in certain repairs categories, were identified and their emissions were measured before and after the repairs in this study. The post-repair nitrogen oxides (NOx) emissions decreased by 46%–75% for check-engine-light-on vehicles and by 53%–81% for MIL-on vehicles at different test speeds. NOx reductions for more than 55% of the vehicles showed reductions greater than 80% for at least one test speed. Pre-repair opacity readings from these HDVs were mostly lower than 5%, except for 6 vehicles that showed the opacity readings from 5.3% to 12.3%. After the repairs, opacity readings for all vehicles were below 5%, and average reductions of 43% in opacity were found for both check-engine-light-on and MIL-on cases. The testing results suggest that an OBD-based HDV I/M program would provide significant and tangible emission benefits. Image 1 • More than 45% of the tested vehicles showed NOx reductions greater than 80%. • Vehicles with check engine light on had an average NOx reduction of 75% at 30 mph. • Vehicles with malfunction indicator light on had an average NOx reduction of 81%. • Fleet average reductions of 43% in opacity were found for SCR-equipped vehicles. • The pre-repair opacity readings were 5% or less for all but 6 vehicles. [ABSTRACT FROM AUTHOR]

This paper scrutinizes the assertion that knowledge gaps concerning health risks from climate change are unjust, and must be addressed, because they hinder evidence-led interventions to protect vulnerable populations. First, we construct a taxonomy of six inter-related forms of invisibility (social marginalization, forced invisibility by migrants, spatial marginalization, neglected diseases, mental health, uneven climatic monitoring and forecasting) which underlie systematic biases in current understanding of these risks in Latin America, and advocate an approach to climate-health research that draws on intersectionality theory to address these inter-relations. We propose that these invisibilities should be understood as outcomes of structural imbalances in power and resources rather than as haphazard blindspots in scientific and state knowledge. Our thesis, drawing on theories of governmentality, is that context-dependent tensions condition whether or not benefits of making vulnerable populations legible to the state outweigh costs. To be seen is to be politically counted and eligible for rights, yet evidence demonstrates the perils of visibility to disempowered people. For example, flood-relief efforts in remote Amazonia expose marginalized urban river-dwellers to the traumatic prospect of forced relocation and social and economic upheaval. Finally, drawing on research on citizenship in post-colonial settings, we conceptualize climate change as an 'open moment' of political rupture, and propose strategies of social accountability, empowerment and trans-disciplinary research which encourage the marginalized to reach out for greater power. These achievements could reduce drawbacks of state legibility and facilitate socially-just governmental action on climate change adaptation that promotes health for all. • Use invisibility to explore biases in understanding of climate-health risks. • Review invisibilities linked to marginalization of peoples, places, diseases. • Contend that invisibilities arise from structural imbalances in power and resources. • Tension shapes whether the benefits of being seen by the state outweigh the costs. • Propose strategies to enable the marginalized to reach for greater power. [ABSTRACT FROM AUTHOR]