Bottom-up Interactions Research Articles

Top-down and bottom-up interactions rely on nested brain oscillations to shape rhythmic visual attention sampling.

Adaptive visual processing is enabled through the dynamic interplay between top-down and bottom-up (feedback/feedforward) information exchange, presumably propagated through brain oscillations. Here, we causally tested for the oscillatory mechanisms governing this interaction in the human visual system. Using concurrent transcranial magnetic stimulation-electroencephalography (TMS-EEG), we emulated top-down signals by a single TMS pulse over the frontal eye field (right FEF), while manipulating the strength of sensory input through the presentation of moving concentric gratings (compared to a control-TMS site). FEF-TMS without sensory input led to a top-down modulated occipital phase realignment, alongside higher fronto-occipital phase connectivity, in the alpha/beta band. Sensory input in the absence of FEF-TMS increased occipital gamma activity. Crucially, testing the interaction between top-down and bottom-up processes (FEF-TMS during sensory input) revealed an increased nesting of the bottom-up gamma activity in the alpha/beta-band cycles. This establishes a causal link between phase-to-power coupling and top-down modulation of feedforward signals, providing novel mechanistic insights into how attention interacts with sensory input at the neural level, shaping rhythmic sampling.

Weaker top-down cognitive control and stronger bottom-up signaling transmission as a pathogenesis of schizophrenia

The clinical symptoms of schizophrenia are highly heterogeneous, with the most striking symptoms being cognitive deficits and perceptual disturbances. Cognitive deficits are typically linked to abnormalities in top-down mechanisms, whereas perceptual disturbances stem from dysfunctions in bottom-up processing. However, it remains unclear whether schizophrenia is primarily driven by top-down control mechanisms, bottom-up perceptual processes, or their interaction. We hypothesized that abnormal top-down and bottom-up interactions constitute the neural mechanisms of schizophrenia. Considering that autoencoders can identify hidden data features and support vector machines are capable of automatically locating the classification hyperplane, we developed an improved stacked autoencoder-support vector machine (ISAE-SVM) model for diagnosing schizophrenia based on resting-state functional magnetic resonance imaging data. A permutation test was used to identify the 213 most discriminative functional connections from the model’s output features. Functional connections linking regions of higher cognitive functions and lower perceptual tasks were extracted to further examine their relevance to clinical symptoms. Finally, spectral dynamic causal modeling (sDCM) was used to analyze the dynamic causal interaction between brain regions corresponding to these functional connections. Our results showed that the ISAE-SVM model achieved an average classification accuracy of 82%. Notably, five resting-state functional connections spanning both cognitive and sensory brain areas were significantly correlated with Positive and Negative Syndrome Scale scores. Furthermore, sDCM analysis revealed weakened top-down regulation and enhanced bottom-up signaling in schizophrenia. These findings support our hypothesis that impaired top-down regulation and enhanced bottom-up signaling contribute to the neural mechanisms of schizophrenia.

Functional and effective connectivity between reward and inhibitory control networks underlying subclinical binge eating.

Knowledge is growing on the essential role of neural circuits involved in aberrant cognitive control and reward sensitivity for the onset and maintenance of binge eating. To investigate how the brain's reward (bottom-up) and inhibition control (top-down) systems potentially and dynamically interact to contribute to subclinical binge eating. Functional magnetic resonance imaging data were acquired from 30 binge eaters and 29 controls while participants performed a food reward Go/NoGo task. Dynamic causal modelling with the parametric empirical Bayes framework, a novel brain connectivity technique, was used to examine between-group differences in the directional influence between reward and executive control regions. We explored the proximal risk factors for binge eating and its neural basis, and assessed the predictive ability of neural indices on future disordered eating and body weight. The binge eating group relative to controls displayed fewer reward-inhibition undirectional and directional synchronisations (i.e. medial orbitofrontal cortex [mOFC]-superior parietal gyrus [SPG] connectivity, mOFC → SPG excitatory connectivity) during food reward_nogo condition. Trait impulsivity is a key proximal factor that could weaken the mOFC-SPG connectivity and exacerbate binge eating. Crucially, this core mOFC-SPG connectivity successfully predicted binge eating frequency 6 months later. These findings point to a particularly important role of the bottom-up interactions between cortical reward and frontoparietal control circuits in subclinical binge eating, which offers novel insights into the neural hierarchical mechanisms underlying problematic eating, and may have implications for the early identification of individuals suffering from strong binge eating-associated symptomatology in the general population.

Analysis of the top-down and bottom-up effects on zooplankton biomass in eutrophic Lake Yeniçağa

Several aquatic ecological studies have focused on the contrasting effects of top-down and bottom-up interactions on zooplankton communities. It is essential to comprehend the relative strength of these interactions to evaluate the trophic interactions of pelagic food webs, an area that is still extensively researched due to its complexity. Therefore, we examined the biomass of zooplankton over a one-year period in a freshwater lake that is subject to multiple stressors such as anthropogenic activities, eutrophication. Top-down effects, namely fish biomass, and bottom-up effects, including total phosphorus, total nitrogen, and chlorophyll a concentrations were considered. Structural equation modelling (SEM) was employed to evaluate the relative impact of top-down and bottom-up effects on zooplankton. The SEM analysis revealed that zooplankton is influenced by both top-down and bottom-up effects in Lake Yeniçağa. The biomass of cladocerans was found to have a negative correlation with increasing chlorophyll a, while the Calanoida group was negatively affected by both fish biomass and chlorophyll a from top-down and bottom-up controls. The fish biomass had a positive effect on both Cyclopoida and Rotifera, but only Rotifera showed a negative interaction with chlorophyll a. Direct bottom-up effects of total phosphorus and total nitrogen on chlorophyll a were found, with total nitrogen having a stronger interaction than total phosphorus.

Water availability and biological interactions shape amphibian abundance and diversity in Mediterranean temporary rivers

Water availability and biological interactions shape amphibian abundance and diversity in Mediterranean temporary rivers

Are Interactive Exhibits at a Science Center Cognitive Artifacts?

AbstractThe paper examines the semiotic and cognitive status of interactive exhibits at science centers, taking the Copernicus Science Center in Warsaw (CSC) as an example. Such science centers support bottom-up interactions, encouraging visitors to spontaneously explore the exhibits in various ways. We analyze one distinctive way of interaction, when young visitors ignore an exhibit’s instruction and use it as if it were a kind of a toy or machine to play with (this is particularly common with exhibits that are unfamiliar “open-ended objects”). Drawing on cognitive semiotics we describe this particular way of interacting with exhibits as the reality mode of experience, in which the user ignores an intended exhibit’s representational function. We consider whether such interactive objects can be framed as cognitive artifacts, given that standard conceptualizations of artifacts emphasize their representational function. How can we convincingly describe the process by which the cognitive function of an exhibit experienced in reality mode is constituted? In this paper we apply concept of ecological cognitive artifact and the idea of the enactive signification to these questions. We argue that exhibits experienced in reality mode do indeed perform cognitive functions, even in the absence of a representational relation. Our investigation provides insights into the cognitive functions of exhibits and contributes to the conceptualization of non-representational cognitive artifacts.

Special Issue on Control and Applications of Multi-Agent Systems

“Multi-agent systems (MAS)” have been extensively studied across various fields, including robotics, economics, biology, and computer science. A distinctive feature of these systems is the ability of multiple agents, each with different characteristics, to perform system-wide tasks through local bottom-up interactions. Furthermore, design and control methods for system networks based on graph theory are being developed. Recent applications of these methods include autonomous driving technology, smart grids, and understanding social systems. This special issue aims to deepen the understanding of MAS, focusing on their control and applications. It features 16 papers, including one review paper. The accepted papers cover a wide range of topics, including reinforcement learning, autonomous mobility systems, and machine learning, presenting the latest research findings on MAS. These studies provide valuable insights into various aspects and potential applications of MAS. We hope that this issue will be beneficial to our readers and contribute to the advancement of future research.

Subcortical contributions to salience network functioning during negative emotional processing

Core regions of the salience network (SN), including the anterior insula (aINS) and dorsal anterior cingulate cortex (dACC), coordinate rapid adaptive changes in attentional and autonomic processes in response to negative emotional events. In doing so, the SN incorporates bottom-up signals from subcortical brain regions, such as the amygdala and periaqueductal gray (PAG). However, the precise influence of these subcortical regions is not well understood. Using ultra-high field 7-Tesla functional magnetic resonance imaging, this study investigated the bottom-up interactions of the amygdala and PAG with the SN during negative emotional salience processing. Thirty-seven healthy participants completed an emotional oddball paradigm designed to elicit a salient negative emotional response via the presentation of random, task-irrelevant negative emotional images. Negative emotional processing was associated with prominent activation in the SN, spanning the amygdala, PAG, aINS, and dACC. Consistent with previous research, analysis using dynamic causal modelling revealed an excitatory influence from the amygdala to the aINS, dACC, and PAG. In contrast, the PAG showed an inhibitory influence on amygdala, aINS and dACC activity. Our findings suggest that the amygdala may amplify the processing of negative emotional stimuli in the SN to enable upstream access to attentional resources. In comparison, the inhibitory influence of the PAG possibly reflects its involvement in modulating sympathetic-parasympathetic autonomic arousal mediated by the SN. This PAG-mediated effect may be driven by amygdala input and facilitate bottom-up processing of negative emotional stimuli. Overall, our results show that the amygdala and PAG modulate divergent functions of the SN during negative emotional processing.

Microstates of Dynamic Directed Connectivity Networks Revealing Visual Color Influences on the Brain Information Processing During Learning

Color has the exceptional ability to capture visual attention and is also capable of enhancing positive emotions, leading to a significant impact on human learning and memory. However, the influence of color on the spatiotemporal dynamics of brain connectivity networks during learning has remained unexplored. This study aimed to propose an analytical approach based on time-frequency decomposition and microstate analysis to capture temporal variations in dynamic directed connectivity networks using electroencephalography (EEG) signals for investigating the influence of visual color on network dynamics of the brain during a learning task. Wavelet transform and phase slope index were employed to estimate the dynamic directed connectivity networks of EEG signals. The estimated dynamic directed connectivity networks were then characterized using graph theoretical analysis. The recurring patterns of dynamic directed connectivity networks were classified using cluster analysis before the temporal dynamics of directed connectivity networks were quantified using microstate analysis. Forty-five healthy participants participated in the experiment, which included memorizing learning materials presented in three different colors (achromatic, cool, and warm). The results revealed that the dynamic directed connectivity networks could be grouped into several quasi-stable states and the presence of common and unique brain states repetitive across frequency bands under individual conditions. A joint analysis of all conditions revealed that the temporal dynamics (coverage, mean duration, and state transition probability) differed significantly between the achromatic and colored conditions. Few dynamic brain states were shared between conditions and tended to remain in particular brain states for a longer duration in specific frequency bands. Our observations provided the first evidence of temporal dynamics of frequency-specific directed connectivity networks in the brain during multimedia learning tasks, that is, increased coverage of top-down interactions in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> bands and switching between top-down and bottom-up interactions (information flow from anterior to posterior regions and vice versa) in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> band, in colored conditions compared to that of achromatic conditions. Therefore, these results suggest that several frequency-specific directed connectivity networks cooperate during knowledge acquisition and may change over time (from one state to another). The proposed framework captures the temporal dynamics of directed connectivity networks, and provides implications for monitoring and assessing emotional and cognitive processes in various contexts.

Clues of Lithosphere, Atmosphere and Ionosphere Variations Possibly Related to the Preparation of La Palma 19 September 2021 Volcano Eruption

On 19 September 2021, La Palma Cumbre Vieja Volcano started an eruption classified as Volcanic Explosive Index (VEI) 3. In this study, at least the six months prior to such an event have been investigated to search for possible lithosphere–atmosphere–ionosphere bottom-up interactions. The lithosphere has been analysed in terms of seismicity getting advantages from the high-density local seismic network. Possible atmospheric alterations related to the volcano emissions or release of gases due to the uplift of the magmatic chamber have been searched in SO2, aerosol, dimethyl sulphide, and CO. The magnetic field on Earth’s surface has been studied by ground geomagnetic observatories. The status of the ionosphere has been investigated with two satellite missions: China Seismo Electromagnetic Satellite (CSES) and European Space Agency Swarm constellation, with Total Electron Content (TEC) retrieved from global maps. We identified a temporal migration of the seismicity from November 2020 at a depth of 40 km that seems associable to magma migration, firstly to a deep chamber at about 15 km depth and in the last 10 days in a shallow magma chamber at less than 5 km depth. The atmospheric composition, ground geomagnetic field, and ionosphere showed anomalies from more than three months before the eruption, suggesting a possible influence from the bottom geo-layers to the upper ones. CSES-01 detected an increase of electron density, confirmed by TEC data, and alterations of vertical magnetic field on ground Guimar observatory that are temporal compatible with some volcanic low seismic activity (very likely due to the magma uplift), suggesting an eventual electromagnetic disturbance from the lithosphere to the ionosphere. A final increase of carbon monoxide 1.5 months before the eruption with unusually high values of TEC suggests the last uplifting of the magma before the eruption, confirmed by a very high shallow seismicity that preceded the eruption by ten days. This work underlines the importance of integrating several observation platforms from ground and overall space to understand geophysics better, and, in particular, the natural hazard affecting our planet.

Cortical-subcortical interactions in goal-directed behavior.

Flexibly selecting appropriate actions in response to complex, ever-changing environments requires both cortical and subcortical regions, which are typically described as participating in a strict hierarchy. In this traditional view, highly specialized subcortical circuits allow for efficient responses to salient stimuli, at the cost of adaptability and context specificity, which are attributed to the neocortex. Their interactions are often described as the cortex providing top-down command signals for subcortical structures to implement; however, as available technologies develop, studies increasingly demonstrate that behavior is represented by brainwide activity and that even subcortical structures contain early signals of choice, suggesting that behavioral functions emerge as a result of different regions interacting as truly collaborative networks. In this review, we discuss the field's evolving understanding of how cortical and subcortical regions in placental mammals interact cooperatively, not only via top-down cortical-subcortical inputs but through bottom-up interactions, especially via the thalamus. We describe our current understanding of the circuitry of both the cortex and two exemplar subcortical structures, the superior colliculus and striatum, to identify which information is prioritized by which regions. We then describe the functional circuits these regions form with one another, and the thalamus, to create parallel loops and complex networks for brainwide information flow. Finally, we challenge the classic view that functional modules are contained within specific brain regions; instead, we propose that certain regions prioritize specific types of information over others, but the subnetworks they form, defined by their anatomical connections and functional dynamics, are the basis of true specialization.

Information Transmission in Delay-Coupled Neuronal Circuits in the Presence of a Relay Population.

Synchronization between neuronal populations is hypothesized to play a crucial role in the communication between brain networks. The binding of features, or the association of computations occurring in spatially segregated areas, is supposed to take place when a stable synchronization between cortical areas occurs. While a direct cortico-cortical connection typically fails to support this mechanism, the participation of a third area, a relay element, mediating in the communication was proposed to overcome this limitation. Among the different structures that could play the role of coordination during the binding process, the thalamus is the best placed region to carry out this task. In this paper we study how information flows in a canonical motif that mimics a cortico-thalamo-cortical circuit composed by three mutually coupled neuronal populations (also called the V-motif). Through extensive numerical simulations, we found that the amount of information transferred between the oscillating neuronal populations is determined by the delay in their connections and the mismatch in their oscillation frequencies (detuning). While the transmission from a cortical population is mostly restricted to positive detuning, transmission from the relay (thalamic) population to the cortical populations is robust for a broad range of detuning values, including negative values, while permitting feedback communication from the cortex at high frequencies, thus supporting robust bottom up and top down interaction. In this case, a strong feedback transmission between the cortex to thalamus supports the possibility of robust bottom-up and top-down interactions in this motif. Interestingly, adding a cortico-cortical bidirectional connection to the V-motif (C-motif) expands the dynamics of the system with distinct operation modes. While overall transmission efficiency is decreased, new communication channels establish cortico-thalamo-cortical association loops. Switching between operation modes depends on the synaptic strength of the cortico-cortical connections. Our results support a role of the transthalamic V-motif in the binding of spatially segregated cortical computations, and suggest an important regulatory role of the direct cortico-cortical connection.

Foliar Aphid Herbivory Alters the Tomato Rhizosphere Microbiome, but Initial Soil Community Determines the Legacy Effects

Aboveground herbivory can impact the root-associated microbiome, while simultaneously different soil microbial communities influence herbivore performance. It is currently unclear how these reciprocal top-down and bottom-up interactions between plants, insects and microbes vary across different soils and over successive plant generations. In this study, we examined top-down impacts of above-ground herbivory on the rhizosphere microbiome across different soils, assessed bottom-up impacts of soil microbial community variation on herbivore performance, and evaluated their respective contributions to soil legacy effects on herbivore performance. We used Macrosiphum euphorbiae (potato aphid) and Solanum pimpinellifolium (wild tomato) to capture pre-domestication microbiome interactions with a specialist pest. First, using 16S rRNA sequencing we compared bacterial communities associated with rhizospheres of aphid-infested and uninfested control plants grown in three different soils over three time points. High aphid infestation impacted rhizosphere bacterial diversity in a soil-dependent manner, ranging from a 22% decrease to a 21% increase relative to uninfested plants and explained 6–7% of community composition differences in two of three soils. We next investigated bottom-up and soil legacy effects of aphid herbivory by growing wild tomatoes in each of the three soils and a sterilized “no microbiome” soil, infesting with aphids (phase one), then planting a second generation (phase two) of plants in the soil conditioned with aphid-infested or uninfested control plants. In the first phase, aphid performance varied across plants grown in different soil sources, ranging from a 20 to 50% increase in aphid performance compared to the “no microbiome” control soil, demonstrating a bottom-up role for soil microbial community. In the second phase, initial soil community, but not previous aphid infestation, impacted aphid performance on plants. Thus, while herbivory altered the rhizosphere microbiome in a soil community-dependent manner, the bottom-up interaction between the microbial community and the plant, not top-down effects of prior herbivore infestation, affected herbivore performance in the following plant generation. These findings suggest that the bottom-up effects of the soil microbial community play an overriding role in herbivore performance in both current and future plant generations and thus are an important target for sustainable control of herbivory in agroecosystems.

Soil engineering by ants facilitates plant compensation for large herbivore removal of aboveground biomass.

The interplay between top-down and bottom-up processes determines ecosystem productivity. Yet, the factors that mediate the balance between these opposing forces remain poorly understood. Furthering this challenge, complex and often cryptic factors like ecosystem engineering and trait-mediated interactions may play major roles in mediating the outcomes of top-down and bottom-up interactions. In semiarid grasslands of northeastern China, we conducted a large-scale, three-year experiment to evaluate how soil engineering by ants and plasticity in plants independently and jointly influenced the top-down effects of grazing by a ubiquitous herbivore (cattle) on aboveground standing biomass of the dominant perennial grass, Leymus chinensis. Herbivory had strong top-down effects, reducing L. chinensis AB by 25% relative to baseline levels without cattle or ants. In contrast, soil engineering by ants facilitated weak bottom-up effects in the absence of herbivory. However, in the presence of herbivory, soil engineering effects were strong enough to fully offset herbivore removal of aboveground biomass. This outcome was mediated by L. chinensis's plasticity in reallocating growth from below- to aboveground biomass, a result linked to additive effects of engineers and herbivores increasing soil N availability and engineering effects improving soil structure. Soil engineering increased soil N by 12%, promoting aboveground biomass. Herbivores increased soil N by 13% via defecation, but this increase failed to offset their reductions in aboveground biomass in isolation. However, when combined, engineers and herbivores increased soil N by 26% and engineers improved soil bulk density, facilitating L. chinensis to shift resource allocations from below- to aboveground biomass sufficiently to fully offset herbivore suppression of aboveground biomass. Our results demonstrate that soil engineering and trait-mediated effects of plant plasticity can strongly mediate the outcome of top-down and bottom-up interactions. These cryptic but perhaps ubiquitous processes may help to explain the long-debated phenomenon of plant compensatory responses to large grazers.

A review of the non-indigenous Chinese mystery snail, Cipangopaludina chinensis (Viviparidae), in North America, with emphasis on occurrence in Canada and the potential impact on indigenous aquatic species

Evidence suggests that the Chinese mystery snail, Cipangopaludina chinensis, a freshwater, dioecious, snail of Asian origin has become invasive in North America, Belgium, and the Netherlands. Invasive species threaten indigenous biodiversity and have socioeconomic consequences where invasive. The aim of this review is to synthesize the relevant literature pertaining to C. chinensis in Canada. In doing so, we (i) describe C. chinensis ecosystem interactions in both indigenous (Asia) and non-indigenous habitats (North America and Europe), (ii) identify gaps in the literature, and (iii) determine where the species potential distribution in North America requires further exploration. We also briefly discuss potential management strategies for this species, as an aquatic invasive species (AIS), in Canada. Due to the much larger relative size of adult C. chinensis, multiple feeding mechanisms, and resistance to predation, C. chinensis can out-compete and displace indigenous freshwater gastropods and other molluscs. Furthermore, C. chinensis can affect food webs through bottom-up interactions with the bacterial and zooplankton communities by changing nitrogen and phosphorous concentrations. Also, the Chinese literature indicates the potential for C. chinensis to act as a biotransfer of contaminants between polluted ecosystems and consumers. In its indigenous range, C. chinensis was identified as a host for numerous parasites harmful to human and animal consumers alike. A comparison of the Canadian geographical distribution of reported occurrences with that for the United States indicates several potential gaps in Canadian reporting, which merits further investigation and consideration, especially in regard to federal and provincial non-indigenous monitoring and regulations. Southern Ontario had the highest number of reports that were mostly from web-based photo-supported sources. This suggests that interactive citizen science through popular apps backed by well-supported educational campaigns may be a highly effective means of tracking C. chinensis spread, which can be complementary to traditional methods using specimen-vouchered taxonomically verified natural-history collections overseen by professional curators.

Controlling risks in the safe city: The rise of pre-emptive practices in law enforcement, public surveillance and mental health and addiction care (1970–2020)

This article describes pre-emptive practices in law enforcement, public surveillance and mental health and addiction care in the Dutch city Amersfoort and the Netherlands in general between 1970 and 2020. These developments are driven by top-down as well as bottom-up interactions on an urban level. The development of this ‘preventive gaze’, though intensified by 9/11, has deeper origins in the urban crisis: the struggle against communal crime and the heroin epidemic in circumstances of austerity encouraged a shift from post-hoc repression to prevention of public nuisance. This shift is analysed in light of the concepts of the risk society, the culture of control and the Disneyisation of inner cities, and its legal and moral implications are assessed. Aiming at unknown future risks, the ‘precautionary culture’ itself risks encroaching on the freedoms of citizens, ultimately making cities less safe.

Integrating top-down and bottom-up effects of local density across scales and a complex life cycle.

Effects of group size (local conspecific density) on individual performance can be substantial, yet it is unclear how these translate to larger-scale and longer-term outcomes. Effects of group size can be mediated by both top-down and bottom-up interactions, can change in type or direction across the life cycle, and can depend on the spatial scale at which group size is assessed. Only by determining how these different processes combine can we make predictions about how selection operates on group size or link hierarchical patterns of density dependence with population dynamics. We manipulated the density of a leaf beetle, Leptinotarsa juncta, at three nested spatial scales (patch, plant within a patch, and leaf within plant) to investigate how conspecific density affects predator-mediated survival and resource-mediated growth during different life stages and across multiple spatial scales. We then used data from field predation experiments to assess how L.juncta densities at hierarchical scales affect different aspects of predation. Finally, we incorporated predator- and resource-mediated effects of density in a model to explore how changes in group size due to density-dependent predation might affect mass at pupation for survivors. The effects of L.juncta density on predation risk differed among scales. Per capita predation risk of both eggs and late instars was lowest at high patch-scale densities, but increased with plant-scale density. The final mass of late instars declined with increasing plant-scale larval density, potentially because of truncated development of high-density larvae. Predation incidence (i.e., group attack rate) increased with larval density at all spatial scales. A high coefficient of variation (i.e., greater aggregation) of L.juncta density was associated with lower predation incidence at some scales. Our model suggested that predator- and resource-mediated effects of density interact: lower survival at high larval density is mitigated by high final mass of larvae in the resulting smaller groups. Our results emphasize the importance of spatial scale and demonstrate that effects of top-down and bottom-up interactions are not necessarily independent. To understand how group size influences fitness, predator- and resource-mediated effects of density should be measured in their demographic and spatial context, and not in isolation.

Agent-based modelling as a tool for elephant poaching mitigation

Agent-based modelling as a tool for elephant poaching mitigation

Atmosphere in Participatory Design

ABSTRACTThe relationship between democracy and design has been the topic of significant discussion in the design community. It is also at the core of participatory design that relies on the principle of genuine participation. According to this, users are not mere informants but legitimate participants in the design process. A great deal of participatory design, however, is driven by instrumental logics rather than participatory and democratic principles. In analysing these power relations, science and technology studies (STS) provides the starting point to introduce the concepts of ‘engineering an atmosphere’ (i.e. the process) and ‘engineered atmosphere’ (i.e. the outcome). These concepts problematise the principles and modes of participatory design, highlighting the tensions between economic and social agendas and top-down and bottom-up interactions. This problematic can be shown in the way that new teachnologies are targeted at older populations, necessitating an interrogation of the processes underpirnning the design and development of technological products and devices. It is important to reflect on who is included and who is excluded from technological design and innovation, which is always, and necessarily so, a fluid process.

Global change-driven modulation of bottom-up forces and cascading effects on biocontrol services.

Global change-driven modulation of bottom-up forces and cascading effects on biocontrol services.