Plant roots steer resilience to perturbation of river floodplains

Freshwater ecosystems along river floodplains host among the greatest biodiversity on Earth and are known to respond to anthropic pressure. For water impounded systems, resilience to changes in the natural flow regime is believed to be bi-directional. Whether such resilience prevents the system from returning to pristine conditions after the flow regime changes reverse is as yet unclear, though widely documented. In this work we show that temporal irreversibility of river floodplains to recover their status may be explained by the dynamics of riparian water-tolerant plant roots. Our model is a quantitative tool that will benefit scientists and practitioners in predicting the impact of changing flow regimes on long-term river floodplain dynamics

Globular clusters as probes of dark matter cusp-core transformations

Bursty star formation in dwarf galaxies can slowly transform a steep dark matter cusp into a constant density core. We explore the possibility that globular clusters (GCs) retain a dynamical memory of this transformation. To test this, we use the nbody6df code to simulate the dynamical evolution of GCs, including stellar evolution, orbiting in static and time-varying potentials for a Hubble time. We find that GCs orbiting within a cored dark matter halo, or within a halo that has undergone a cusp-core transformation, grow to a size that is substantially larger ($R_{\rm eff} > 10$ pc) than those in a static cusped dark matter halo. They also produce much less tidal debris. We find that the cleanest signal of an historic cusp-core transformation is the presence of large GCs with tidal debris. However, the effect is small and will be challenging to observe in real galaxies. Finally, we qualitatively compare our simulated GCs with the observed GC populations in the Fornax, NGC 6822, IKN and Sagittarius dwarf galaxies. We find that the GCs in these dwarf galaxies are systematically larger ($\langle R_{\rm eff}\rangle \simeq 7.8$ pc), and have substantially more scatter in their sizes, than in-situ metal rich GCs in the Milky Way and young massive star clusters forming in M83 ($\langle R_{\rm eff} \rangle \simeq 2.5$ pc). We show that the size, scatter and survival of GCs in dwarf galaxies are all consistent with them having evolved in a constant density core, or a potential that has undergone a cusp-core transformation, but not in a dark matter cusp.Comment: 14 pages, 10 figure

Fluid-induced transition from banded kyanite- to bimineralic eclogite and implications for the evolution of cratons

Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 �C/km to reach peak conditions of 5.8 GPa and 890 �C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 �C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The d18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of d18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compressio

A palaeoenvironmental study of particle size-specific connectivity- new insights and implications from the West Sussex Rother Catchment, United Kingdom

Connectivity has become an important conceptual and practical framework for understanding and managing sediment transfers across hillslopes, between hillslopes and rivers and between rivers and other compartments along the river corridor (e.g. reservoirs, channel substrate, floodplain). Conventionally, connectivity focuses on the quantity of sediment transferred but here we also consider the size of the finer sediment (typically particles < 500 µm diameter). We examine the role of small rapidly silting reservoirs in the River Rother on storing sediment and disrupting downstream sediment transfers. Spatial and temporal changes in the particle size characteristics of sediment deposited in one of the ponds is explored in detail. Downstream of this pond we collected sediment from the river on nine occasions over 17 months using two sampling methods at two locations; one immediately downstream of the pond and a second ~700 m further downstream but upstream of the confluence with the Rother. Results showed a significant depletion in sand sized particles immediately downstream of the pond but the sand had been recovered from an in-channel source before the river reached the downstream sampling point

Risks, alternative knowledge strategies and democratic legitimacy: the conflict over co-incineration of hazardous industrial waste in Portugal.

The decision to incinerate hazardous industrial waste in cement plants (the socalled ‘co-incineration’ process) gave rise to one of the most heated environmental conflicts ever to take place in Portugal. The bitterest period was between 1997 and 2002, after the government had made a decision. Strong protests by residents, environmental organizations, opposition parties, and some members of the scientific community forced the government to backtrack and to seek scientific legitimacy for the process through scientific expertise. The experts ratified the government’s decision, stating that the risks involved were socially acceptable. The conflict persisted over a decade and ended up clearing the way for a more sustainable method over which there was broad social consensus – a multifunctional method which makes it possible to treat, recover and regenerate most wastes. Focusing the analysis on this conflict, this paper has three aims: (1) to discuss the implications of the fact that expertise was ‘confiscated’ after the government had committed itself to the decision to implement co-incineration and by way of a reaction to the atmosphere of tension and protest; (2) to analyse the uses of the notions of ‘risk’ and ‘uncertainty’ in scientific reports from both experts and counter-experts’ committees, and their different assumptions about controllability and criteria for considering certain practices to be sufficiently safe for the public; and (3) to show how the existence of different technical scientific and political attitudes (one more closely tied to government and the corporate interests of the cement plants, the other closer to the environmental values of reuse and recycling and respect for the risk perception of residents who challenged the facilities) is closely bound up with problems of democratic legitimacy. This conflict showed how adopting more sustainable and lower-risk policies implies a broader view of democratic legitimacy, one which involves both civic movements and citizens themselves

Industrial constructions of publics and public knowledge: a qualitative investigation of practice in the UK chemicals industry

This is a post print version of the article. The official published version can be obtained from the link below - © 2007 by SAGE PublicationsWhile the rhetoric of public engagement is increasingly commonplace within industry, there has been little research that examines how lay knowledge is conceptualized and whether it is really used within companies. Using the chemicals sector as an example, this paper explores how companies conceive of publics and "public knowledge," and how this relates to modes of engagement/communication with them. Drawing on qualitative empirical research in four companies, we demonstrate that the public for industry are primarily conceived as "consumers" and "neighbours," having concerns that should be allayed rather than as groups with knowledge meriting engagement. We conclude by highlighting the dissonance between current advocacy of engagement and the discourses and practices prevalent within industry, and highlight the need for more realistic strategies for industry/public engagement.Funding was received from the ESRC Science in Society Programme

As a Pediatrician, I Don’t Know the Second, Third, or Fourth Thing to Do: A Qualitative Study of Pediatric Residents’ Training and Experiences in Behavioral Health

Despite a mandated 1-month rotation in developmental-behavioral pediatrics (DBP), pediatric residents report inadequate training in behavioral health care. As a first step in much needed curriculum development in this area, this study sought to assess learner experiences regarding the management of behavioral health problems during residency. Four focus groups were conducted for residents in years 1-3 of training in 2 residency programs in a northeastern state. Transcripts were analyzed and coded by researchers through qualitative classical content analysis. The exploratory analysis revealed 9 key themes: time requirements, rapport building, resources and referrals for behavioral health, psychiatric medications, diagnosis vs. treatment, working with families, the importance of behavioral health, fears of working with a pediatric population, and training issues. These qualitative data further identify gaps in the behavioral health training of pediatric residents and may inform future innovations in training curricula

Structural complexity influences the ecosystem engineering effects of instream large wood

Large wood (LW) is an ecosystem engineer and keystone structure in river ecosystems, influencing a range of hydromorphological and ecological processes and contributing to habitat heterogeneity and ecosystem condition. LW is increasingly being used in catchment restoration, but restored LW jams have been observed to differ in physical structure to naturally occurring jams, with potential implications for restoration outcomes. This article examines the structural complexity and ecosystem engineering effects of LW jams at four sites with varying management intensity incorporating natural and restored wood. Our results reveal: (i) structural complexity and volume of jams was highest in the site with natural jams and low intensity riparian management, and lowest in the suburban site with simple restored jams; and (ii) that structural complexity influences the ecosystem engineering role of LW, with more complex jams generating the greatest effects on flow hydraulics (flow concentration, into bed flows) and sediment characteristics (D50, organic content, fine sediment retention) and the simplest flow deflector-style restored jams having the least pronounced effects. We present a conceptual model describing a continuum of increasing jam structural complexity and associated hydromorphological effects that can be used as a basis for positioning and evaluating other sites along the management intensity spectrum to help inform restoration design and best practice