2,538 research outputs found
How long is a hillslope?
Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope–area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope–area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length–relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridgetop pixel in a DEM, we show that the resulting population of hillslope length–relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient
Unheard voices: practice based arts research and the PID landscape
A breakout session at Repository Fringe in Edinburgh in 2018 began the discussion on capturing practice-based arts research in repositories in the UK and discussed the fact that many repository systems don’t adequately reflect what this research looks like. At a similar time the UK focussed Practice Research Advisory Group – a researcher led community – was having discussions about how to ensure this research is discoverable and preserved for the long term. Awareness and experiences captured by these communities led Jisc to hold an event in March 2019 on Capturing Practice Research: improving visibility and searchability. What had been a UK focussed discussion was then taken to an international audience with a panel discussion session at Open Repositories in 2019 in Hamburg. These discussions have identified that the persistent identifier landscape isn’t really an even playing field for this research which doesn’t tend to look like other, more traditional forms of research.
This session aimed to bring together interested people from all over the world to talk about PIDs in practice-based arts research. It started with a brief case study on the experience at the University of Westminster, based in London in the UK, who engaged with their practice-based arts research community (and supplier Haplo) to develop their new open source repository software to identify what this research looks like and how the repository could better reflect it. We then highlighted how various Persistent Identifiers don’t quite fit the practice-research landscape – or where they could do, how and where practitioners require more specific guidance that addresses practice research. Without this, the many benefits of the PID graph/landscape are not available to the practice-based research community. The specific examples we covered included: ORCID iDs, DOIs, RAID and the CRediT taxonomy
From legacy to next generation: a story of collaboration to push the boundaries of the open source Haplo repository from Cayuse
This article describes the development of the Haplo standards-based, open source repository software, from Cayuse, that meets the findable, accessible, interoperable and reusable (FAIR) principles, and which captures all research, regardless of what it is, with a focus on prioritizing the capture of ‘practice research’ – ‘… an umbrella term that describes all manners of research where practice is the significant method of research conveyed in a research output.’ in the arts and architecture. This research has been neglected by the repository landscape and surrounding discoverability infrastructure, which has traditionally focused on text-based research publications in the STEM disciplines where there is a policy mandate (and funding) for open access. As practice research has not been captured effectively in repositories, it has not been possible for it to be preserved for long-term access via appropriate integrated digital preservation solutions. This story of collaboration between the University of Westminster and Haplo (now Cayuse), puts researchers at the centre of development, using a co-design approach, while ensuring the Research and Scholarly Communications team (then based within the Library and Archives Service) at the University were driving this work in alignment with sector-wide standards. The role of user engagement, advocacy and inclusive policy development is highlighted and illustrates that this underpins, and is crucial to, successful software development. While the successes are documented and celebrated, the challenges are acknowledged and the lessons learned are shared
Practice made Practical. Reducing the OTHER of non-text
The academy has become increasingly expert at the creation and description of STEM textual articles and data along with building platforms for their discovery, access and inquiry. However, for disciplines where outputs are not typically textual in nature, such as architecture, practice research, etc. there are still many challenges in the way these outputs and related resources are described. We propose that working with existing expert communities, such as repositories that have built taxonomies to address these outputs, we can build the vocabularies of the wider global infrastructure - the persistent identifiers and metadata that underpin scholarly information networks - so that the work types are richer, more descriptive, allowing better discoverability, and bringing a future where all aspects of research are equally valued
van der Waals epitaxy of monolayer hexagonal boron nitride on copper foil : growth, crystallography and electronic band structure
We investigate the growth of hexagonal boron nitride (h-BN) on copper foil by low pressure chemical vapour deposition (LP-CVD). At low pressure, h-BN growth proceeds through the nucleation and growth of triangular islands. Comparison between the orientation of the islands and the local crystallographic orientation of the polycrystalline copper foil reveals an epitaxial relation between the copper and h-BN, even on Cu(100) and Cu(110) regions whose symmetry is not matched to the h-BN. However, the growth rate is faster and the islands more uniformly oriented on Cu(111) grains. Angle resolved photoemission spectroscopy measurements reveal a well-defined band structure for the h-BN, consistent with a band gap of 6 eV, that is decoupled from the copper surface beneath. These results indicate that, despite a weak interaction between h-BN and copper, van der Waals epitaxy defines the long range ordering of h-BN even on polycrystalline copper foils and suggest that large area, single crystal, monolayer h-BN could be readily and cheaply produced
Low temperature removal of surface oxides and hydrocarbons from Ge(100) using atomic hydrogen
Germanium is a group IV semiconductor with many current and potential applications in the modern semiconductor industry. Key to expanding the use of Ge is a reliable method for the removal of surface contamination, including oxides which are naturally formed during the exposure of Ge thin films to atmospheric conditions. A process for achieving this task at lower temperatures would be highly advantageous, where the underlying device architecture will not diffuse through the Ge film while also avoiding electronic damage induced by ion irradiation. Atomic hydrogen cleaning (AHC) offers a low temperature, damage-free alternative to the common ion bombardment and annealing (IBA) technique which is widely employed. In this work, we demonstrate with xray photoelectron spectroscopy (XPS) that the AHC method is effective in removing surface oxides and hydrocarbons, yielding an almost completely clean surface when the AHC is conducted at a temperature of 250 â—¦C. We compare the post-AHC cleanliness and
(2 × 1) low energy electron diffraction (LEED) pattern to that obtained via IBA, where the sample is annealed at 600 ◦C. We also demonstrate that the combination of a sample temperature of 250 ◦C and atomic H dosing is required to clean the surface. Lower temperatures prove less effective in removal of the oxide layer and hydrocarbons, whilst annealing in ultra-high vacuum conditions only removes weakly bound hydrocarbons. Finally, we examine the subsequent H-termination of an IBA-cleaned sample using XPS, LEED and ultraviolet photoelectron spectroscopy (UPS) in order to examine changes in the work function of Ge(100) upon hydrogenation
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