School of Geography, Earth and Atmospheric Sciences - Research Publications
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ItemPrecarity, illicit markets, and the 'mystery' of prices(Taylor and Francis Group, 2023)Stand-alone price analysis of illicit opium and coca does not explain why smallholders turn to illicit crops for coping and survival. Under conditions of precarity, illicit crop markets can stimulate productivity. They generate returns that can tame crises and relieve pressures. To smallholders facing marginalisation, violence, and climate change – growing opium and coca, despite their illegality, can reduce or spread risks and provide more predictability. Thus, rather than fix on the ‘invisible hand’ of price theory, the focus should be on the ‘visible hand’ of political entrepreneurship, interdependent relationships, and the metrics of precarity. To do this, this paper retrospectively compares illicit crop prices before and after certain historical moments in Bolivia, Myanmar, Colombia, and Afghanistan.
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ItemCriminal entrepreneurs as pioneers, intermediaries, and arbitrageurs in borderland economies(ELSEVIER, 2021-03)Many discussions of mafia and criminal entrepreneurs typically focus on violence and illegality, and less on their possible roles in rural transformation, even when they are located in borderland economies linking the subsistence cultivators of illicit crops to regional and global markets. This paper assesses the life stories of drug lords, the Castaño brothers of Colombia and Roberto Suárez Gomez of Bolivia, to draw inferences into how such rural elites in the illicit drugs trade are not only specialists in crime but are also actors who regulate and manipulate, often coercively, access to land and resources, mobilise labour and shape its divisions, and promote certain forms of capital accumulation. This paper contends that a better understanding of the roles of these rural elites as pioneers for capital, intermediaries in commodity chains, and arbitrageurs between state and borderlands may provide ways of unpacking key challenges to peacebuilding and economic transformation in borderlands where illicit economies thrive.
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ItemThe paradox of illicit economies: survival, resilience, and the limits of development and drug policy orthodoxy(Taylor and Francis Group, 2020)The illicit drug crops opium and coca are conventionally regarded as sources of instability, an ‘evil’ that breeds fragility and violence. Fragile states are supposed to be most vulnerable to their production and consequent harms. Yet by looking into the local contexts of the world’s leading opium and coca producers – Afghanistan, Myanmar, Colombia and Bolivia – these illicit crops are found to also be sources of stability, even drivers of economic growth. They enable marginalized communities and territories abandoned by the state to be reinserted into national and global markets. Within so-called ‘fragile’ and conflict-affected areas are displaced and dispossessed households adopting innovative and unorthodox strategies for coping and survival in changing and insecure environments. This paper maps out an approach, useful for examining the resilience that has emerged amidst violence and uncertainty in illicit-crop-producing territories, and which can hopefully tackle the continuing disconnect between drugs and development policy.
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ItemBringing the forest back: Restoration priorities in Colombia(Wiley, 2024-04)Aim: Colombia has committed to ambitious forest restoration targets which include a 1 million ha Bonn Challenge commitment and 6.47–8.31 million ha (rehabilitation and restoration, respectively) under the National Restoration Plan. Determining where and how to implement programs to achieve these targets remains a significant challenge. Location: Colombia. Methods: We adopt a multi‐objective optimisation framework for restoration planning and apply it to Colombia. We explore cost‐effective solutions that leverage the potential for assisted natural regeneration benefits while accounting for opportunity and establishment costs of restoration and maximising biodiversity conservation and climate change mitigation benefits. We explore four politically relevant restoration area‐based targets (1, 6, 6.47 and 8.31 million ha) and identify minimum cost, and suites of maximum benefit and cost‐effective solutions. Results: We identify solutions that simultaneously perform well across biodiversity and carbon objectives, despite trade‐offs between these objectives. We find that cost‐effective solutions can achieve on average 91.1%, 90.8%, 90.5% and 90.1% of maximum carbon benefit and 100% of the maximum biodiversity benefit while significantly reducing costs. On average, the cost‐effective solutions reduce the cost by 87.5%, 56.8%, 59.6% and 46.2% compared to the maximum benefit solutions considering one, six, 6.47 and 8.31 million ha restoration targets, respectively. Main Conclusions: Colombia has committed to bold restoration and conservation targets, such as those under the new 2030 Convention on Biological Diversity Global Biodiversity Framework. Strategic forest restoration planning will play an important role in achieving Colombia's biodiversity conservation and climate mitigation goals. We provide quantitative evidence to inform planning for environmentally and economically sensible restoration policy and practice in the country. Our framework and results can help guide Colombia towards meeting its ambitious forest restoration targets cost‐effectively.
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ItemA field work report on newly discovered and documented megalithic jar sites in the Lao People’s Democratic Republic(Springer Science and Business Media LLC, 2023-12)Abstract Xieng Khouang and neighboring provinces in Central Laos are home to a vast megalithic landscape featuring large stone jars, discs, and imported boulders located in elevated positions. Sites were first noted in the late nineteenth century, with systematic recording commencing in the 1930s. Continuing on from the 2019 field survey by the Plain of Jars Archaeological Research Project, this paper presents the results of a 2020 survey across Xieng Khouang Province, Lao People’s Democratic Republic (PDR) which led to the documentation of 27 previously unreported megalithic sites, growing the Lao PDR Government database from 102 to 127 known jar sites, with 124 geo-located. In addition, a preliminary analysis of the known jar sites to date is conducted regarding distribution and jar characteristics providing a basis for further investigation.
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ItemMicroglial ferroptotic stress causes non-cell autonomous neuronal death(BMC, 2024-02-05)BACKGROUND: Ferroptosis is a form of regulated cell death characterised by lipid peroxidation as the terminal endpoint and a requirement for iron. Although it protects against cancer and infection, ferroptosis is also implicated in causing neuronal death in degenerative diseases of the central nervous system (CNS). The precise role for ferroptosis in causing neuronal death is yet to be fully resolved. METHODS: To elucidate the role of ferroptosis in neuronal death we utilised co-culture and conditioned medium transfer experiments involving microglia, astrocytes and neurones. We ratified clinical significance of our cell culture findings via assessment of human CNS tissue from cases of the fatal, paralysing neurodegenerative condition of amyotrophic lateral sclerosis (ALS). We utilised the SOD1G37R mouse model of ALS and a CNS-permeant ferroptosis inhibitor to verify pharmacological significance in vivo. RESULTS: We found that sublethal ferroptotic stress selectively affecting microglia triggers an inflammatory cascade that results in non-cell autonomous neuronal death. Central to this cascade is the conversion of astrocytes to a neurotoxic state. We show that spinal cord tissue from human cases of ALS exhibits a signature of ferroptosis that encompasses atomic, molecular and biochemical features. Further, we show the molecular correlation between ferroptosis and neurotoxic astrocytes evident in human ALS-affected spinal cord is recapitulated in the SOD1G37R mouse model where treatment with a CNS-permeant ferroptosis inhibitor, CuII(atsm), ameliorated these markers and was neuroprotective. CONCLUSIONS: By showing that microglia responding to sublethal ferroptotic stress culminates in non-cell autonomous neuronal death, our results implicate microglial ferroptotic stress as a rectifiable cause of neuronal death in neurodegenerative disease. As ferroptosis is currently primarily regarded as an intrinsic cell death phenomenon, these results introduce an entirely new pathophysiological role for ferroptosis in disease.
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ItemThe distribution of fossil pollen and charcoal in stalagmites(CAMBRIDGE UNIV PRESS, 2023-05-16)Abstract Pollen preserved in caves provides a little-appreciated opportunity to study past vegetation and climate changes in regions where conventional wetland sediments are either unavailable, contain little organic matter, and/or are difficult to date accurately. Most palynology in caves has focused on clastic infill sediments, but pollen preserved in growing speleothems provides important new opportunities to develop vegetation and climatic records that can be dated accurately with radiometric methods. However, when pollen is present in speleothems, concentrations can vary by orders of magnitude, highlighting how little we know about the processes that transport pollen into caves and onto speleothem surfaces, and that determine the pollen's preservation probability. To explore these aspects of speleothem pollen taphonomy, we investigated the distribution of pollen and microscopic charcoal within several stalagmites from southwest Australia. We examined spatial patterns in pollen and charcoal preservation in order to distinguish whether observed gradients result from preservation or are products of systematic transport processes working along stalagmite surfaces. We find that pollen grains and charcoal fragments are located preferentially on the flanks of most stalagmites. This suggests that pollen grain and charcoal deposition on speleothems is influenced by transport and accumulation of detrital debris on growing surfaces. These insights will assist in future sampling campaigns focusing on speleothem pollen and charcoal contents.
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ItemNo Preview AvailableOn the relationship between mesoscale cellular convection and meteorological forcing: comparing the Southern Ocean against the North Pacific(Copernicus GmbH, 2023-12-20)Abstract. Marine atmospheric boundary layer (MABL) clouds cover vast areas over the ocean and have important radiative effects on the Earth's climate system. These radiative effects are known to be sensitive to the local organization, or structure, of the mesoscale cellular convection (MCC). A convolutional neural network model is used to identify the two idealized classes of MCC clouds, namely open and closed, over the Southern Ocean (SO) and Northwest Pacific (NP) from high-frequency geostationary Himawari-8 satellite observations. The results of the climatology show that MCC clouds are evenly distributed over the mid-latitude storm tracks for both hemispheres, with peaks poleward of the 40∘ latitude. Open-MCC clouds are more prevalent than closed MCC in both regions. An examination of the presumed meteorological forcing associated with open- and closed-MCC clouds is conducted to illustrate the influence of large-scale meteorological conditions. We establish the importance of the Kuroshio western boundary current in the spatial coverage of open and closed MCC across the NP, presumably through the supply of strong heat and moisture fluxes during marine cold-air outbreaks events. In regions where static stability is higher, we observe a more frequent occurrence of closed MCCs. This behavior contrasts markedly with that of open MCCs, whose formation and persistence are significantly influenced by the difference in temperature between the air and the sea surface. The occurrence frequency of closed MCC over the SO exhibits a significant diurnal cycle, while the diurnal cycle of closed MCC over the NP is less noticeable.
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ItemNo Preview AvailableEvidence for decreased copper associated with demyelination in the corpus callosum of cuprizone-treated mice(OXFORD UNIV PRESS, 2024-01-05)Demyelination within the central nervous system (CNS) is a significant feature of debilitating neurological diseases such as multiple sclerosis and administering the copper-selective chelatorcuprizone to mice is widely used to model demyelination in vivo. Conspicuous demyelination within the corpus callosum is generally attributed to cuprizone's ability to restrict copper availability in this vulnerable brain region. However, the small number of studies that have assessed copper in brain tissue from cuprizone-treated mice have produced seemingly conflicting outcomes, leaving the role of CNS copper availability in demyelination unresolved. Herein we describe our assessment of copper concentrations in brain samples from mice treated with cuprizone for 40 d. Importantly, we applied an inductively coupled plasma mass spectrometry methodology that enabled assessment of copper partitioned into soluble and insoluble fractions within distinct brain regions, including the corpus callosum. Our results show that cuprizone-induced demyelination in the corpus callosum was associated with decreased soluble copper in this brain region. Insoluble copper in the corpus callosum was unaffected, as were pools of soluble and insoluble copper in other brain regions. Treatment with the blood-brain barrier permeant copper compound CuII(atsm) increased brain copper levels and this was most pronounced in the soluble fraction of the corpus callosum. This effect was associated with significant mitigation of cuprizone-induced demyelination. These results provide support for the involvement of decreased CNS copper availability in demyelination in the cuprizone model. Relevance to human demyelinating disease is discussed.
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ItemNo Preview AvailablePotential to use free satellite imagery to retrieve the past bathymetry of large rivers(Elsevier BV, 2024-01-01)