On the dynamics of vortex modes within magnetic islands

Recent work investigating the interaction of magnetic islands with micro-turbulence has uncovered the striking observation of large scale vortex modes forming within the island structure [W.A. Hornsby {\it et al.}, Phys. Plasmas {\bf 17} 092301 (2010)]. These electrostatic vortices are found to be the size of the island and are oscillatory. It is this oscillatory behaviour and the presence of turbulence that leads us to believe that the dynamics are related to the Geodesic Acoustic Mode (GAM), and it is this link that is investigated in this paper. Here we derive an equation for the GAM in the MHD limit, in the presence of a magnetic island modified three-dimensional axisymmetric geometry. The eigenvalues and eigenfunctions are calculated numerically and then utilised to analyse the dynamics of oscillatory large-scale electrostatic potential structures seen in both linear and non-linear gyro-kinetic simulations

Macroinvertebrate communities in streams with contrasting water sources in the Japanese Alps

Alpine streams are typically fed from a range of water sources including glacial meltwater, snowmelt, groundwater flow, and surface rainfall runoff. These contributions are projected to shift with climate change, particularly in the Japanese Alps where snow is expected to decrease, but rainfall events increase. The overarching aim of the study was to understand the key variables driving macroinvertebrate community composition in groundwater and snowmelt-fed streams (n = 6) in the Kamikochi region of the northern Japanese Alps (April–December 2017). Macroinvertebrate abundance, species richness, and diversity were not significantly different between the two stream types. Community structure, however, was different between groundwater and snowmelt-fed streams with macroinvertebrate taxa specialized for the environmental conditions present in each system. Temporal variation in the abundance, species richness, and diversity of macroinvertebrate communities was also significantly different between groundwater and snowmelt streams over the study period, with snowmelt streams exhibiting far higher levels of variation. Two snowmelt streams considered perennial proved to be intermittent with periodic drying of the streambed, but the macroinvertebrates in these systems rebounded rapidly after flows resumed with no reduction in taxonomic diversity. These same streams, nevertheless, showed a major reduction in diversity and abundance following periods of high flow, indicating floods rather than periodic drying was a major driver of community structure. This conclusion was also supported from functional analyses, which showed that the more variable snowmelt streams were characterized by taxa with resistant, rather than resilient, life-history traits. The findings demonstrate the potential for significant turnover in species composition with changing environmental conditions in Japanese alpine stream systems, with groundwater-fed streams potentially more resilient to future changes in comparison to snowmelt-fed streams

Crystal Symmetry Lowering in Chiral Multiferroic Ba3_3TaFe3_3Si2_2O14_{14} observed by X-Ray Magnetic Scattering

Chiral multiferroic langasites have attracted attention due to their doubly-chiral magnetic ground state within an enantiomorphic crystal. We report on a detailed resonant soft X-ray diffraction study of the multiferroic Ba$_3$TaFe$_3$Si$_2$O$_{14}$ at the Fe $L_{2,3}$ and oxygen $K$ edges. Below $T_N$ ($\approx27K$) we observe the satellite reflections $(0,0,\tau)$, $(0,0,2\tau)$, $(0,0,3\tau)$ and $(0,0,1-3\tau)$ where $\tau \approx 0.140 \pm 0.001$. The dependence of the scattering intensity on X-ray polarization and azimuthal angle indicate that the odd harmonics are dominated by the out-of-plane ($\mathbf{\hat{c}}$-axis) magnetic dipole while the $(0,0,2\tau)$ originates from the electron density distortions accompanying magnetic order. We observe dissimilar energy dependences of the diffraction intensity of the purely magnetic odd-harmonic satellites at the Fe $L_3$ edge. Utilizing first-principles calculations, we show that this is a consequence of the loss of threefold crystal symmetry in the multiferroic phase

Microplastic ingestion by riverine macroinvertebrates

Although microplastics are a recognised pollutant in marine environments, less attention has been directed towards freshwater ecosystems despite their greater proximity to possible plastic sources. Here, we quantify the presence of microplastic particles (MPs) in river organisms upstream and downstream of five UK Wastewater Treatment Works (WwTWs). MPs were identified in approximately 50% of macroinvertebrate samples collected (Baetidae, Heptageniidae and Hydropsychidae) at concentrations up to 0.14 MP mg tissue−1 and they occurred at all sites. MP abundance was associated with macroinvertebrate biomass and taxonomic family, but MPs occurred independently of feeding guild and biological traits such as habitat affinity and ecological niche. There was no increase in plastic ingestion downstream of WwTW discharges averaged across sites, but MP abundance in macroinvertebrates marginally increased where effluent discharges contributed more to total runoff and declined with increasing river discharge. The ubiquity of microplastics within macroinvertebrates in this case study reveals a potential risk from MPs entering riverine food webs through at least two pathways, involving detritivory and filter-feeding, and we recommend closer attention to freshwater ecosystems in future research

Food web transfer of plastics to an apex riverine predator

As a rapidly accelerating expression of global change, plastics now occur extensively in freshwater ecosystems, yet there is barely any evidence of their transfer through food webs. Following previous observations that plastics occur widely in their prey, we used a field study of free‐living Eurasian dippers (Cinclus cinclus ), to test the hypotheses that (1) plastics are transferred from prey to predators in rivers, (2) plastics contained in prey are transferred by adults to altricial offspring during provisioning and (3) plastic concentrations in faecal and regurgitated pellets from dippers increase with urbanization. Plastic occurred in 50% of regurgitates (n = 74) and 45% of faecal samples (n = 92) collected non‐invasively from adult and nestling dippers at 15 sites across South Wales (UK). Over 95% of particles were fibres, and concentrations in samples increased with urban land cover. Fourier transform infrared spectroscopy identified multiple polymers, including polyester, polypropylene, polyvinyl chloride and vinyl chloride copolymers. Although characterized by uncertainty, steady‐state models using energetic data along with plastic concentration in prey and excreta suggest that around 200 plastic particles are ingested daily by dippers, but also excreted at rates that suggest transitory throughput. As some of the first evidence revealing that plastic is now being transferred through freshwater food webs, and between adult passerines and their offspring, these data emphasize the need to appraise the potential ecotoxicological consequences of increasing plastic pollution

An Integrative framework of buyer-supplier negative relationship quality and dysfunctional interfirm conflict

Purpose: Problems of relationship quality and interfirm conflict in business to business settings are serious concerns that need to be addressed. Thus, the authors have engaged in an extensive review to promote an understanding of these complex issues. This paper develops an integrated framework for analyzing wide-ranging relations between individual representatives and patterns of interfirm incompatibility for managerial control. Methodology/Approach: The review involves numerous sources that include articles and monographs. A theoretical framework is constructed to integrate fragmented empirical data. In particular, social identity and commitment-trust theories are mobilized for this framework. Findings: The review of studies has a substantial consistency with the theoretical framework. The paper outlines a causal chain from interpersonal agent dissimilarities to dysfunctional buyer-supplier relations, culminating in interfirm pathological conflict. Moderating factors in the causal chain are: agent identity differentiation (for interpersonal dissimilarity), supplier relations mismanagement (for buyer-supplier relationship quality), and interfirm opportunism (for interfirm pathological conflict). Buyer-supplier interfirm incompatibility mediates the causal link between interpersonal dissimilarity and buyer-supplier relationship quality. Identity differentiation, the validation of one’s self-image, is introduced as a process that determines buyer-supplier agent interpersonal dissimilarity judgments. This framework employs a contextual perspective. It describes interactions between observations of micro-level phenomena of interpersonal dissimilarities and macro-level models of interfirm fit. From a managerial perspective, interpersonal relations between individual buyer and supplier agents may be further strengthened by such strategies as expanding the scope of the interpersonal relationship, relaxation of role responsibilities, and volunteering business-related contact referrals. Originality/Value: A new theoretical framework has been devised to predict and explain relationship quality and interfirm pathological conflict in the B to B context. The framework contributes to the value of the knowledge base by serving as a means for building new diagnostic tools for assessment of interfirm behavioral issues affecting exchanges. New concepts are introduced to enhance current literature on B to B marketing. The framework provides concrete indicators that operationally define ideas and enable or improve measurement for empirical modeling

Endocrine disruption in aquatic systems: up-scaling research to address ecological consequences

Endocrine-disrupting chemicals (EDCs) can alter biological function in organisms at environmentally relevant concentrations and are a significant threat to aquatic biodiversity, but there is little understanding of exposure consequences for populations, communities and ecosystems. The pervasive nature of EDCs within aquatic environments and their multiple sub-lethal effects make assessments of their impact especially important but also highly challenging. Herein, we review the data on EDC effects in aquatic systems focusing on studies assessing populations and ecosystems, and including how biotic and abiotic processes may affect, and be affected by, responses to EDCs. Recent research indicates a significant influence of behavioural responses (e.g. enhancing feeding rates), transgenerational effects and trophic cascades in the ecological consequences of EDC exposure. In addition, interactions between EDCs and other chemical, physical and biological factors generate uncertainty in our understanding of the ecological effects of EDCs within aquatic ecosystems. We illustrate how effect thresholds for EDCs generated from individual-based experimental bioassays of the types commonly applied using chemical test guidelines [e.g. Organisation for Economic Co-operation and Development (OECD)] may not necessarily reflect the hazards associated with endocrine disruption. We argue that improved risk assessment for EDCs in aquatic ecosystems urgently requires more ecologically oriented research as well as field-based assessments at population-, community- and food-web levels

Bad apples in bad barrels revisited: Cognitive moral development, just world beliefs, rewards, and ethical decision-making

In this study, we test the interactive effect on ethical decision-making of (1) personal characteristics, and (2) personal expectancies based on perceptions of organizational rewards and punishments. Personal characteristics studied were cognitive moral development and belief in a just world. Using an in-basket simulation, we found that exposure to reward system information influenced managers' outcome expectancies. Further, outcome expectancies and belief in a just world interacted with managers' cognitive moral development to influence managers' ethical decision-making. In particular, low-cognitive moral development managers who expected that their organization condoned unethical behavior made less ethical decisions while high cognitive moral development managers became more ethical in this environment. Low cognitive moral development managers also behaved less ethically when their belief in a just world was high