1,712 research outputs found
Trion formation resolves observed peak shifts in the optical spectra of transition metal dichalcogenides
Monolayer transition metal dichalcogenides (TMDs) have the potential to
unlock novel photonic and chemical technologies if their optoelectronic
properties can be understood and controlled. Yet, recent work has offered
contradictory explanations for how TMD absorption spectra change with carrier
concentration, fluence, and time. Here, we test our hypothesis that the large
broadening and shifting of the strong band-edge features observed in optical
spectra arise from the formation of negative trions. We do this by fitting an
ab initio based, many-body model to our experimental electrochemical data. Our
approach provides an excellent, global description of the potential-dependent
linear absorption data. We further leverage our model to demonstrate that trion
formation explains the non-monotonic potential dependence of the transient
absorption spectra, including through photoinduced derivative lineshapes for
the trion peak. Our results motivate the continued development of theoretical
methods to describe cutting-edge experiments in a physically transparent way.Comment: 5 pages, 5 figures main text. 4 pages, 6 figures, several passages of
pseudocode SI, 66 reference
Consequences of fish kills for long-term trophic structure in shallow lakes: implications for theory and restoration
Fish kills are a common occurrence in shallow, eutrophic lakes, but their ecological consequences, especially in the long-term, are poorly understood. We studied the decadal-scale response of two UK shallow lakes to fish kills using a palaeolimnological approach. Eutrophic and turbid Barningham Lake experienced two fish kills in the early 1950s and late 1970s with fish recovering after both events, whereas less eutrophic, macrophyte-dominated Wolterton Lake experienced one kill event in the early 1970s from which fish failed to recover. Our palaeo-data show fish-driven trophic cascade effects across all trophic levels (covering benthic and pelagic species) in both lakes regardless of pre-kill macrophyte coverage and trophic status. In turbid Barningham Lake, similar to long-term studies of biomanipulations in other eutrophic lakes, effects at the macrophyte-level are shown to be temporary after the first kill (c.20 years) and non-existent after the second kill. In plant-dominated Wolterton Lake permanent fish disappearance failed to halt a long-term pattern of macrophyte community change (e.g. loss of charophytes and over-wintering macrophyte species) symptomatic of eutrophication. Important implications for theory and restoration ecology arise from our study. Firstly, our data support ideas of slow eutrophication-driven change in shallow lakes where perturbations are not necessary prerequisites for macrophyte loss. Secondly, the study emphasises a key need for lake managers to reduce external nutrient-loading if sustainable and long-term lake restoration is to be achieved. Our research highlights the enormous potential of multi-indicator palaeolimnology and alludes to an important need to consider potential fish kill signatures when interpreting results
Piketty's Calibration Economics: Inequality and the Dissolution of Solutions?
© 2015 Taylor & Francis. Abstract: By popularising interest in inequality, Thomas Piketty's Capital in the Twenty-First Century has made a significant contribution. It has helped to change the basic terms of debate regarding wealth and income. However, Capital exhibits several weaknesses. The overall statement of Piketty's 3 laws tends to confuse the reader by conflating capital with all forms of wealth, and capital with the current market valuation of wealth assets. The whole creates a form of empiricism by metrics or calibration. The aggregation also lends itself to data as history rather than as historically grounded explanation of evidence. Concomitantly, it lacks a theorisation of capitalism, of power, of the state, of social movements, and of social transformations. This affects the way in which possible solutions to inequality are conceived. However, it does provoke further grounds for ethical counterargument productive of more progressive solutions to the problems it highlights
Influences on academics' approaches to development: voices from below
The purpose of this qualitative case study research was to explore faculty-based academicsâ views on what influences their behaviours and attitudes towards their development. Informed by critical realist ontology, the data collection was carried out through narrative interviews with academics in two contrasting English Universities. Findings, or areas for reflection, have emerged about the constraints and enablements academics perceive in respect of their professional development. In particular, themes such as the significance of professional status; misaligned initiatives and priorities; the influence of supportive networks; and emergent personal, individual concerns have surfaced. The conclusion is drawn that the significance of agency raises the importance of responding to the âvoices from belowâ
Participation after multidisciplinary rehabilitation for moderate to severe traumatic brain injury in adults: A systematic review
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Where constructionism and critical realism converge: interrogating the domain of epistemological relativism
The paper interrogates the status, nature and significance of epistemological relativism as a key element of constructionism and critical realism. It finds that epistemological relativism is espoused by authorities in critical realism and marginalized or displaced in the field of management and organization studies, resulting in forms of analysis that are empirically, but not fully critically, realist. This evaluation prompts reflection on the question of whether, how and with what implications epistemological relativism might be recast at the heart of critical realist studies of management and organization
South Australian Digital Youth Survey Research Report: Year 2 Results
This report was produced by The Digital Youth Research Laboratory.Morgan Sayer, Tyson Whitten, Russell Brewer, Jesse Cale, Thomas Holt and Andrew Goldsmit
The biodiversity benefit of native forests and mixed-species plantations over monoculture plantations
Aim: China's Grain for Green Program (GFGP) is the largest reforestation programme in the world and has been operating since 1999. The GFGP has promoted the establishment of tree plantations over the restoration of diverse native forests. In a previous study, we showed that native forests support a higher species richness and abundance of birds and bees than do GFGP plantations and that mixed-species GFGP plantations support a higher level of bird (but not bee) diversity than do any individual GFGP monocultures (although still below that of native forests). Here, we use metabarcoding of arthropod diversity to test the generality of these results. Location: Sichuan, China. Methods: We sampled arthropod communities using pan traps in the land cover types concerned under the GFGP. These land use types include croplands (the land cover being reforested under the GFGP), native forests (the reference ecosystem as the benchmark for the GFGPâs biodiversity effects) and the dominant GFGP reforestation outcomes: monoculture and mixed-species plantations. We used COI-amplicon sequencing (âmetabarcodingâ) of the arthropod samples to quantify and assess the arthropod community profiles associated with each land cover type. Results: Native forests support the highest overall levels of arthropod species diversity, followed by mixed-species plantations, followed by bamboo and other monocultures. Also, the arthropod community in native forests shares more species with mixed-species plantations than it does with any of the monocultures. Together, these results broadly corroborate our previous conclusions on birds and bees but show a higher arthropod biodiversity value of mixed-species plantations than previously indicated by bees alone. Main conclusion: In our previous study, we recommended that GFGP should prioritize the conservation and restoration of native forests. Also, where plantations are to be used, we recommended that the GFGP should promote mixed-species arrangements over monocultures. Both these recommendations should result in more effective protection of terrestrial biodiversity, which is an important objective of China's land-sustainability spending. The results of this study strengthen these recommendations because our policy prescriptions are now also based on a dataset that includes over 500 species-resolution taxa, ranging across the Arthropoda
Updated extinction risk assessments of Madagascarâs freshwater decapod crustaceans reveal fewer threatened species but more Data Deficient species.
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