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The chapter summarises the main findings from the SDG chapters (1–17) combined with the results from a workshop in 2018 to answer the following questions: How is Agenda 2030 likely to interact with forests and people? What are the possible synergies, trade-offs between goals and targets? What are the contextual conditions that shape the interactions between SDGs and targets and subsequent impacts on forests and people? Two broad groups of SDGs emerge. One includes SDGs that primarily focus on institutional, governance and social conditions. Those contribute to an enabling environment for inclusive forest management and conservation with associated livelihood benefits. A second group of SDGs affect land use directly and thus are expected to impact forests. Progress in the first group of SDGs results in synergistic interactions and positive outcomes for forests and peoples. Among the second group of SDGs, the potential for trade-offs is high, with important repercussions for forest and people. Understanding the potential for these trade-offs is essential in order to avoid implementation pathways that favour a small subset of these SDGs at the expense of the others.
Paternalist policymakers face a severe knowledge problem that is analogous to the knowledge problem faced by central planners. They do not and often cannot possess the kind of local and tacit knowledge needed to craft policy interventions that reliably improve human welfare. We provide a taxonomy of types of knowledge that paternalist planners need but typically do not have: true preferences, extent of bias, self-debiasing and small-group debiasing, dynamic impacts on self-regulation, counteracting behaviors, bias interactions, and population heterogeneity. We also critique two leading efforts to surmount knowledge problems of behavioral paternalism: the augmented revelatory frame approach and unified behavioral revealed preference.
The fluid–structure interactions (FSI) of compliant lifting surfaces is complicated by free-surface and multiphase flows such as cavitation and ventilation. This paper describes the dynamic FSI response of a flexible surface-piercing hydrofoil in dry, wetted, ventilating and cavitating conditions. Experimental modal analysis is used to quantify the resonant frequencies and damping ratios of the fluid–structure system in each flow regime. The generalized hydrodynamic stiffness, fluid damping and fluid added mass are also determined as ratios to the corresponding structural modal forces. Added mass increases with increasing partial immersion of the hydrofoil and decreases in the presence of gaseous cavities. In particular, modal frequencies were observed to increase significantly in fully ventilated flow compared to fully wetted flow. The modal frequencies varied non-monotonically with speed in fully wetted flow. Gaseous cavities reduced the modal added mass and reduced the fluid disturbing force. Modal damping increases non-monotonically with increasing immersion depth. Forward speed causes the fluid damping force to increase with an approximately quadratic functional behaviour, consistent with a series expansion of the Morison equation, although damping identification became increasingly difficult at high flow speeds. The results indicate that fluid damping is greater than the associated structural damping in a quiescent liquid, and increasingly so with increasing immersion, suggesting viscous dissipation as a dominant mechanism. A preliminary investigation of modal vibration as a means of controlling the size and stability of ventilated cavities indicates that low-order modes encourage the formation of ventilation, while higher-order modes encourage the washout and elimination of ventilation.
Sketching is a natural and intuitive communication tool used for expressing concepts or ideas which are difficult to communicate through text or speech alone. Sketching is therefore used for a variety of purposes, from the expression of ideas on two-dimensional (2D) physical media, to object creation, manipulation, or deformation in three-dimensional (3D) immersive environments. This variety in sketching activities brings about a range of technologies which, while having similar scope, namely that of recording and interpreting the sketch gesture to effect some interaction, adopt different interpretation approaches according to the environment in which the sketch is drawn. In fields such as product design, sketches are drawn at various stages of the design process, and therefore, designers would benefit from sketch interpretation technologies which support these differing interactions. However, research typically focuses on one aspect of sketch interpretation and modeling such that literature on available technologies is fragmented and dispersed. In this paper, we bring together the relevant literature describing technologies which can support the product design industry, namely technologies which support the interpretation of sketches drawn on 2D media, sketch-based search interactions, as well as sketch gestures drawn in 3D media. This paper, therefore, gives a holistic view of the algorithmic support that can be provided in the design process. In so doing, we highlight the research gaps and future research directions required to provide full sketch-based interaction support.
Viscous anti-parallel vortex reconnection is studied by means of direct numerical simulation for vortex Reynolds numbers
, circulation/viscosity) up to 40 000. To suppress the inherent symmetry breaking due to the Kelvin–Helmholtz (planar jet) instability, as prevalent in prior studies, and to better explore the progression of the mechanism details, the simulation is performed by imposing symmetry and using double-precision arithmetic. We show, for the first time, the evidence of vortex reconnection cascade scenario initially proposed by Melander and Hussain (CTR Report, 1988), who suggested that the remnant threads, following the first reconnection, undergo successive reconnections in a cascade. Secondary reconnection (the details distinctly captured and visualized at a lower
) leads to the successive generation of numerous small-scale structures, including vortex rings, hairpin-like vortex packets and vortex tangles. As
increases, the third and higher generations of reconnection form a turbulent cloud avalanche consisting of a tangle of fine vortices. The energy is rapidly transferred to finer scales during reconnection, and a distinct - 5/3 inertial range is observed for the kinetic energy spectrum, associated with numerous resulting fine-scale bridgelets and thread filaments. In addition, we also discover an inverse cascade at large scales through the accumulation of bridgelets. The separation distance
before the first reconnection is found to scale as
, which is different from the typical 1/2 scaling for classical and quantum vortex filament reconnections. Both peak enstrophy and its production rate grow with
faster than the power law suggested by Hussain and Duraisamy (Phys. Fluids, vol. 23, 2011, 021701). Our simulations not only reveal the detailed mechanisms of high-
reconnection, but also shed light on the physics of turbulence cascade and present the reconnection avalanche as a realistic physical model for turbulence cascade.
The spatial and temporal structure of the resonant fluid response in a narrow gap (the so-called gap resonance) between two identical fixed boxes is investigated experimentally. Transient wave groups are used to excite the gap resonance from different wave approach directions. This shows a strong beating pattern and a very long duration, reflecting that gap resonance is a multi-mode resonant and weakly damped phenomenon. For head sea excitation the linear transfer function of the
gap mode is as significant as that of the
mode. Gap resonance can be driven through different mechanisms, e.g. linear excitation and a nonlinear frequency-doubling process. Significant wave group structure is shown in the gap, and the group structure is more distinct in the case with frequency doubling, i.e. long wave, excitation. Then it is clearer visually that the groups originate at the end of the gap, propagate along the gap and are then partially reflected from the other end. The groups within the gap are very clear because the group velocity is close to constant for the first few gap resonance modes, and much smaller than that for free waves on the open sea. In contrast, the phase speed of waves in the gap is larger than that for free waves outside. Only in the limit of short waves do the group velocity and phase speed of the gap modes tend to those of deep-water free waves. The group and phase speeds from these experiments match well the theoretical forms given by Molin et al. (Appl. Ocean Res., vol. 24 (5), 2002, pp. 247–260), albeit for a slightly different box cross-sectional shape.
Introductions of predators can have strong effects on native ecosystems and knowledge of the prey size selection of invasive predators is pivotal to understand their impact on native prey and intraguild competitors. Here, we investigated the prey size selection of two invasive crabs (Hemigrapsus sanguineus and Hemigrapsus takanoi) recently invading European coasts and compared them with native shore crabs (Carcinus maenas) which are known to feed on similar prey species. In laboratory experiments, we offered different size classes of native blue mussels (Mytilus edulis) to different size classes of the crab species in an effort to identify the respective prey size preferences and potential overlap in prey size range of native and invasive crabs. In all three species, the preferred prey size increased with crab size reflecting general predator–prey size relationships. Prey size preference did not differ among the crab species, i.e. crabs showed similar mussel size preference in relation to carapace width. Given that additional morphological measurements showed that both of the invasive crab species have much larger claws relative to their body size compared with the native species, this finding was surprising and may relate to differential claw morphologies or structural strength. These results suggest that the invasive crabs exert predation pressure on the same size classes of native mussels as the native crabs, with potential effects on mussel population dynamics due to the high densities of the invaders. In addition, the overlap in prey size range is likely to result in resource competition between invasive and native crabs.
In the marginal ice zone, surface waves drive motion of sea ice floes. The motion of floes relative to each other can cause periodic collisions, and drives the formation of pancake sea ice. Additionally, the motion of floes relative to the water results in turbulence generation at the interface between the ice and ocean below. These are important processes for the formation and growth of pancakes, and likely contribute to wave energy loss. Models and laboratory studies have been used to describe these motions, but there have been no in situ observations of relative ice velocities in a natural wave field. Here, we use shipboard stereo video to measure wave motion and relative motion of pancake floes simultaneously. The relative velocities of pancake floes are typically small compared to wave orbital motion (i.e. floes mostly follow the wave orbits). We find that relative velocities are well-captured by existing phase-resolved models, and are only somewhat over-estimated by using bulk wave parameters. Under the conditions observed, estimates of wave energy loss from ice–ocean turbulence are much larger than from pancake collisions. Increased relative pancake floe velocities in steeper wave fields may then result in more wave attenuation by increasing ice–ocean shear.
Infection severity and persistence in a host population is affected by variation in host susceptibility. External disturbance can exacerbate/reduce individual variation by affecting the interactions between the host and its parasites and the dynamics of infection and transmission. We investigated the impact of three sources of disturbance (climate change, the presence of a second parasite species and anthelmintic treatment) on the dynamics of infection and shedding of three common parasites of the rabbit. Data were collected from long-term field studies and laboratory experiments and analysed using mathematical modelling and analytical tools. Our studies show that they all affect host–parasite interactions by altering the intensity of infection and/or the degree of parasite shedding. They also generate patterns of infections that could not have been predicted in the absence of these disturbances or from performing analyses at a different temporal scale. Modelling simulations confirmed the complexity of the processes involved and identified the critical interactions shaping the patterns observed.
Since the discovery of the magnetosphere-magnetotail system in the1950s-1960s), and the associated beginning of the satellite era, we have gained a well-informed understanding of this space plasma region permeated by the geomagnetic field and home to a variety of charged particle populations and plasma waves. Over the last six decades, IAGA has played an important role in supporting international magnetospheric research. Here we provide an overview of recent developments in energy transport from the solar wind into the Earth’s environment. Topics include, magnetosphere energy input, the role of the boundary layer. Solar wind interaction with the magnetosphere creates geomagnetic activity and the response of the region leading to sub-storms and steady magnetospheric convection are discussed. The charged particle energy (eV to MeV) inherent/contained in the magnetospheric ring current and Van Allen radiation belts establish many properties of the region, giving rise to boundary regions and waves. Results from recent state of the art and currently operating Earth orbiting satellites (Cluster, THEMIS, Van Allen Probes, Magnetosphere MultiScale), are providing exciting new results. Waves from magnetospheric scale ultra-low frequency (ULF) from a few milliHertz, up to upper hybrid waves and continuum radiation in the 1-2 MHz band. Finally, current understanding of the plasmasphere and associated boundary the plasmapause, are considered.
For simplicity’s sake, standard population genetic models of host–parasite coevolution often exclude ecological and epidemiological detail. In particular, they assume that each host is exposed to a single infectious propagule, regardless of the parasite’s prevalence. On the other hand, standard epidemiological models usually assume that all hosts are equally susceptible to infection. Here, we summarise models in which we relax these simplifying assumptions, thereby allowing for feedbacks between evolution, ecology, and epidemiology. One major result from these models is that, under certain general conditions, a parasite’s potential for disease spread (R0) decreases as genetic diversity for resistance increases in the host population. Moreover, R0 can increase if we allow the parasite population to track common host genotypes. Feedbacks between ecology and evolution mean that as a common genotype comes to dominate the host population, the parasite population adapts to preferentially infect this genotype, increasing the prevalence of infection and the mean number of parasite exposures per host. We further connect these findings to the major evolutionary hypothesis that coevolving parasites can favour sexual reproduction.
Invasive species drive biodiversity loss and lead to changes in parasite–host associations. Parasites are linked to invasions and can mediate invasion success and outcomes. We review theoretical and empirical research into parasites in biological invasions, focusing on a freshwater invertebrate study system. We focus on the effects of parasitic infection on host traits (behaviour and life history) that can mediate native/invader trophic interactions. We review evidence from the field and laboratory of parasite-driven changes in predation, intraguild predation and cannibalism. Theoretical work shows that the trait-mediated effects of parasites can be as strong as classical density effects and their impact on the host’s trophic interactions merits more consideration. We also report on evidence of broader cascading effects warranting deeper study. Biological invasion can lead to altered parasite–host associations. Focusing on amphipod invasions, we find patterns of parasite introduction and loss that mirror host invasion pathways, but also highlight the risks of introducing invasive parasites. Horizon scanning and impact predictions are vital in identifying future disease risks, potential pathways of introduction and suitable management measures for mitigation.
Parasites live and interact in multi-species communities. As these interactions are often hidden, the extent to which they occur, their relative strength and consequences are poorly understood. We review work on parasite interactions occurring in free-living African buffalo, which are distributed across the African continent and host a diversity of parasites, from bacteria and viruses to helminths. Three case studies of pairwise interactions between some of the most common and economically important parasites of buffalo shed new light on the effects of parasite interactions for individual hosts and population-level disease dynamics. Work on interactions between macro- and microparasites (common gastrointestinal worm infections and bovine tuberculosis, TB) suggests that immune responses underlie complex interactions. At individual host level, worms enhance TB infection severity, but at population level they can limit TB spread. Analysis of interactions between TB and Rift Valley Fever virus (RVFV) shows that TB presence makes increases RVFV effects. Work into how two dominant members of the worm community living in the buffalo gastrointestinal tract reassemble after perturbation reveals that the processes driving interactions between parasites can be dynamic over time. We use combined approaches to bridge the gap between individual and population scales and show how studies of natural populations can advance understanding of parasite interactions.
Individuals are typically coinfected with multiple parasite species. Laboratory studies have shown that coinfecting parasites can interact strongly within individual hosts with potentially serious consequences for disease progression and successful treatment. Understanding the occurrence of these interactions in natural systems and their effect on host health and parasite epidemiology in the wild are only beginning. Rodents are the ideal ‘wild’ model taxon to study these effects due to their ubiquity, high abundance, ease of capture, diagnostic assessment, and experimentation in their natural setting. Also, their close phylogenetic relatedness to the standard laboratory mouse (Mus musculus) model means that studies of wild rodents have great potential to advance our understanding of the dynamics and mechanisms of coinfection interactions. We review coinfection studies in wild rodents and compare the findings with predictions of general coinfection theory. We show that the relationship between coinfection interactions at the within-host scale and their pattern of association at the host population scale can be complex, as predicted by the general theory. Patterns of parasite association at the host population level can be poor predictors of the occurrence or direction of the underlying within-host interaction.
The geomagnetic field extending outward beyond Earth’s solid surface encounters a strong, highly variable flow of hot ionized gas from the Sun called the solar wind. This compresses and shapes the dayside of Earth’s magnetic field. On the night (anti-sunward) side of the Earth, the magnetic field gets drawn out into a long, comet-like tail. Present evidence is that this magnetotail region extends to hundreds or thousands of Earth radii. Research over the past six decades has revealed much about the various current systems that shape the Earth’s "magnetosphere". This chapter is devoted to providing a broad overview of the individual current systems that, acting together, generate the complex and fascinating geomagnetic field.