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We study the transport and deposition of inhaled aerosols in a mid-generation, mucus-lined lung airway, with the aim of understanding if and how airborne particles can avoid the mucus and deposit on the airway wall – an outcome that is harmful in case of allergens and pathogens, but beneficial in case of aerosolised drugs. We adopt the weighted-residual integral boundary-layer model of Dietze and Ruyer-Quil (J. Fluid Mech. 762, 2015, 68–109, to describe the dynamics of the mucus–air interface, as well as the flow in both phases. The transport of mucus induced by wall-attached cilia is also considered, via a coarse-grained boundary condition at the base of the mucus. We show that the capillary-driven Rayleigh–Plateau instability plays an important role in particle deposition by drawing the mucus into large annular humps and leaving substantial areas of the wall exposed to particles. We find, counter-intuitively, that these mucus-depleted zones enlarge on increasing the mucus volume fraction. Our simulations are eased by the fact that the effects of cilia and air turn out to be rather simple: the long-term interface profile is slowly translated by cilia and is unaffected by the laminar airflow. The streamlines of the airflow, though, are strongly modified by the non-uniform mucus film, and this has important implications for aerosol entrapment. Particles spanning a range of sizes (0.1–50 microns) are modelled using the Maxey–Riley equation, augmented with Brownian forces. We find a non-monotonic dependence of deposition on size. Small particles diffuse across streamlines due to Brownian motion, while large particles are thrown off streamlines by inertial forces – particularly when air flows past mucus humps. Intermediate-sized particles are tracer-like and deposit the least. Remarkably, increasing the mucus volume need not increase entrapment: the effect depends on particle size, because more mucus produces not only deeper humps that intercept inertial particles, but also larger depleted zones that enable diffusive particles to deposit on the wall.
This chapter examines the national-scale origins and political linkages of land mafias and rural militias in Brazil. These linkages, especially to political power, explain how, over just a few decades, an RDPE of active and open land-grabbing mafias has spread from southern Brazil to the Amazon. These cases illustrate the dynamics by which federal-level changes can expand an RDPE system to the national scale and to other parts of the same jurisdiction, polity, and political system. The land-grabbing process is linked to illegalities and violence, which are mutually self-reinforcing through the logics operating in these systems. This chapter examines the rapid post-2019 transformation of pastures into monoculture soybean or corn plantations, especially in southeastern Acre and along the paved BR-163 highway. Part of the problem is the institutionalization of illegal land grabbing and its mafia-like tactics, whose continuation is ensured through legal loopholes and ambiguities. The situation worsened, especially during the reign of Jair Bolsonaro (2019–2023), as land mafia dynamics penetrated deeper into the sociopolitical fabric of Brazil.
This chapter explores the ongoing and novel merging of gold mining with organized crime, highlighting the relation of drug trafficking, land grabbing, and other related sectors to deforestation. The recent gold-mining expansion and boom in the Amazon is linked to gold markets and the global political economy. The chapter scrutinizes the rise of narco-gold mining, linking drug trade, organized criminal groups, and money laundering with rainforest gold and the surge of authoritarian and mafia-like power. During the Bolsonaro era there was a significant deepening of the link between gold-mining activities and organized drug traffickers and criminal networks. In southwestern Pará, gold mining is the leading cause of deforestation inside areas like the upper Tapajós Munduruku Indigenous lands near Jacareacanga. This chapter utilizes field research experiences, interviews, and ethnographic observations to illustrate the complex dilemmas faced by communities currently being pressured and divided by increasing gold extraction in their territories. In the end of the chapter the discussion turns to solutions for how to address these and other root causes of deforestation in political economy.
As gold prices have soared, the Amazon and its inhabitants have had to bear the brunt of a rampant, environmentally destructive gold-mining rush. Small and medium-sized illegal, informal, and other irregular forms of so-called artisanal gold mining, as well as large-scale corporate gold mines, cause major and multifaceted socioenvironmental–health–human rights crises. The dynamics of the gold-mining boom are important to understand the key political economic sectors behind forest degradation and deforestation and to highlight how RDPEs work. The overall situation in the Amazon is presented, analyzing the causes of gold mining and the violence, especially in Peru, Brazil, and other key regions. The triple frontier between Colombia, Venezuela, and Brazil is also analyzed as the irregular gold-mining RDPE is one of the most important drivers of deforestation. In this region, gold-mining operations are led by ex-guerilla groups in Venezuela, paramilitaries and other armed groups in Colombia, and, increasingly, by the First Capital Command and other drug factions from southeastern Brazil in Roraima’s Yanomami Indigenous lands.
A new theoretical framework is required to expose how the underlying political economic systems function and drive deforestation. The hypotheses and case studies are presented while situating deforesting processes in the international system and its many subsystems, which are composed of partially interlinked sectors that often compete for the same land areas. This is a detailed political economic analysis, based on regionally situated world-ecological analyses, which consider the power that different sectors have in causing the loss of forests, such as Brazilian ranching speculation, Amazonian gold mining, and Finnish pulp and energywood forestry. The chapter contends that there is a need to cultivate a deeper, comparative, and global crises-situated understanding of the role these forces have in driving deforesting. One must also understand the local-level enabling factors and the role of resistance. Insights are woven together from several disciplines and approaches such as political ecology and world-ecology into a new conceptual framework that can be widely applied to explain global development dynamics, beyond the specific application to deforestation.
This paper presents the palaeoecological analysis of five latest Pleistocene (17,500–13,500 cal yr BP) Arctic ground squirrel (Urocitellus parryii) middens from three sites in the Klondike goldfields of central Yukon Territory. Plant and invertebrate macrofossil records were represented by 24 and 20 taxa, respectively, providing a record of the local environment and the earliest known occurrences in Yukon Territory for several taxa (e.g., the robber fly [Lasiopogon sp.] and marsh yellowcress [Rorippa cf. palustris]). The plant and invertebrate assemblages indicate the persistence of steppe-tundra to at least 13,680 cal yr BP by the preservation of taxa typically occupying dry sites, many of which remain components of grasslands and south-facing azonal steppe communities in present-day Yukon Territory. In the context of shrub expansion that is documented to have occurred by 14,000 cal yr BP in interior Alaska, we consider the taphonomic biases associated with Arctic ground squirrel middens that may lead to the lack of shrub macrofossils preserved at the sites. Our study provides an ecologically unique and chronologically constrained perspective on the local persistence of steppe-tundra in easternmost Beringia despite the regional expansion of shrubs.
During the Ordovician, the brachiopod order Atrypida originated and diversified. However, speciation patterns and evolutionary drivers within three atrypide Laurentian genera, Anazyga, Catazyga, and Zygospira, remain poorly known. Herein, we propose a Bayesian phylogenetic framework for these clades. Morphological character data, including 34 internal and external characters, were collected for 20 species, including seven species assigned to Zygospira, six species previously assigned to Anazyga, and seven species previously assigned to Catazyga. Morphological data were analyzed in BEAST2.5 via an Mk Model of morphological character evolution implementing the fossilized birth–death (FBD) model. In addition, FBD-based rates of extinction, origination, and fossil sampling were estimated across four Late Ordovician time intervals. Primary results include: (1) each genus was polyphyletic as traditionally established; (2) proposed transfer of all Anazyga and two Catazyga species to Zygospira based on reconstructed evolutionary relationships; (3) recognition of one new species, Zygospira idahoensis Vilela-Andrade n. sp., and the elevation of Z. multicostata Howe, 1965, originally a subspecies, to species status; and (4) updated understanding of clade origination and speciation. The origination age for the clade is calibrated to be 453 Ma (Sandbian 2). Recovered biodiversification rates indicate that the highest speciation and extinction rates occurred in the Katian 3 stage slice, when the number of species in the clade peaked. Subsequently, a decline in biodiversification led to an extinction episode in the Katian 4 for all lineages. Catazyga and Zygospira are interpreted as early Late Ordovician atrypids that experienced both rapid radiation and extinction during the Katian.
This chapter discusses the relation of global extractivisms to global deforestation, making novel claims about the role of forests in the international system. This is a global, world-ecological analysis of why forests seem to have not mattered in the interstate system and how they are still overlooked in favor of a free flow of commodity trade and interstate competition. The impacts of the world system on forests are explored over the past 5,000 years, focusing especially on the past 550 years. “Epochal moments,” for example, wars or events like the COVID-19 pandemic, are particularly detrimental to retaining the world’s old-growth forests. One should avoid overgeneralizations of how global capitalism or humanity (as the “Anthropocene”) drive deforestation. Thus, the chapter utilizes a long-term, world-system perspective, focusing on how the current structures of the world-system drive deforestation. The chapter uncovers how the nature of the interstate system affects the efforts by global environmental governance and other means to try to curb or control deforestation. This curbing is fundamentally restricted by the lobbying and political power of RDPEs.
Peru’s Amazon is the site of a violent and fast-moving gold-mining rush, which has caused divides within Indigenous communities and devastating environmental impacts from the mercury used in gold extractivism. There has been a massive increase in illegal or informal gold mining, especially in Peru’s Madre de Dios province. Tens of thousands of miners operate on rafts in the rivers or dig for gold by increasingly mechanized means. In Madre de Dios there is a gold-mining RDPE that explains the bulk of land and forest use. In addition to an exploration of the dynamics of gold extractivism, this chapter also assesses the conflicts and resistance at play in this context. Indigenous communities, especially in the Amazon, are currently facing huge extractivist pressures, which has started to polarize many communities and change their relationship with the extractivist phenomena. Some community members have started to extract gold illegally and destructively, while most resist these temptations, invoking nonmodernist cosmologies and understandings that place barriers to extractivist expansions.
This study reconstructs the fluvial dynamics of the Bras de Fer distributary in the Rhône Delta (France) during the Little Ice Age (LIA) in response to short-term climatic forcing. A multiproxy approach combining historical cartography, sedimentology, geochemistry, magnetic susceptibility, and hydrological archives reveals accelerated meander migration and extensive overbank accretion between the late seventeenth and early eighteenth centuries CE. Increased flood frequency, coinciding with positive phases of the Atlantic Multidecadal Oscillation (AMO+), promoted rapid lateral channel shifts and the formation of crevasse splay complexes along the outside bank of the Grande Ponche meander. The results demonstrate that, despite stable relative sea levels, deltaic morphology remained highly sensitive to decadal-scale climatic variability, highlighting the dominant role of hydrological extremes in shaping fluvial-deltaic environments of Rhône delta during the late LIA.