Sensitivity of the Lidar ratio to changes in size distribution and index of refraction

In order to invert lidar signals to obtain reliable extinction coefficients, sigma, a relationship between sigma and the backscatter coefficient, beta, must be given. These two coefficients are linearly related if the complex index of refraction, m, particle shape size distribution, N, does not change along the path illuminated by the laser beam. This, however, is generally not the case. An extensive Mie computation of the lidar ratio R = beta/sigma and the sensitivity of R to the changes in a parametric space defined by N and m were examined

Interaction driven real-space condensation

We study real-space condensation in a broad class of stochastic mass transport models. We show that the steady state of such models has a pair-factorised form which generalizes the standard factorized steady states. The condensation in this class of models is driven by interactions which give rise to a spatially extended condensate that differs fundamentally from the previously studied examples. We present numerical results as well as a theoretical analysis of the condensation transition and show that the criterion for condensation is related to the binding-unbinding transition of solid-on-solid interfaces.Comment: 4 page

Condensation transitions in a model for a directed network with weighted links

An exactly solvable model for the rewiring dynamics of weighted, directed networks is introduced. Simulations indicate that the model exhibits two types of condensation: (i) a phase in which, for each node, a finite fraction of its total out-strength condenses onto a single link; (ii) a phase in which a finite fraction of the total weight in the system is directed into a single node. A virtue of the model is that its dynamics can be mapped onto those of a zero-range process with many species of interacting particles -- an exactly solvable model of particles hopping between the sites of a lattice. This mapping, which is described in detail, guides the analysis of the steady state of the network model and leads to theoretical predictions for the conditions under which the different types of condensation may be observed. A further advantage of the mapping is that, by exploiting what is known about exactly solvable generalisations of the zero-range process, one can infer a number of generalisations of the network model and dynamics which remain exactly solvable.Comment: 23 pages, 8 figure

Building a single repository to meet all use cases: a collaboration between institution, researchers and supplier

Repositories have historically focused on a single use case, primarily the capture of traditional (text-based) open access publications, requiring separate solutions for different use cases (e.g. research data). This made capturing the variety of research outputs challenging at the University of Westminster, which engages in practice-based arts research, alongside traditional research. Building on a history of collaboration, Haplo and the University and its research community have built a single, open source repository meeting multiple use cases including text-based and non-text based outputs, portfolios and research data. Made possible through the flexible technical architecture of the Haplo platform, whose underlying technology is based on semantic web principles and meets COAR’s vision for next-generation repositories. Improvements to the repository now enable better capture and display of research outputs across disciplines. Highlights include the development of dynamic portfolios, improved support for non-text based outputs and ongoing engagement with practice-based arts researchers to understand their needs, build workflows, review metadata and build, test and implement a transformed repository

Re-examination of the possible tidal stream in front of the LMC

It has recently been suggested that the stars in a vertical extension of the red clump feature seen in LMC color-magnitude diagrams could belong to a tidal stream of material located in front of that galaxy. If this claim is correct, this foreground concentration of stars could contribute significantly to the rate of gravitational microlensing events observed in the LMC microlensing experiments. Here we present radial velocity measurements of stars in this so-called ``vertical red clump'' (VRC) population. The observed stellar sample, it transpires, has typical LMC kinematics. It is shown that it is improbable that an intervening tidal stream should have the same distribution of radial velocities as the LMC, which is consistent with an earlier study that showed that the VRC feature is more likely a young stellar population in the main body of that galaxy. However, the kinematic data do not discriminate against the possibility that the VRC is an LMC halo population.Comment: 10 pages, 3 figures, 1 table. Accepted for publication in ApJ

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

Spatial Particle Condensation for an Exclusion Process on a Ring

We study the stationary state of a simple exclusion process on a ring which was recently introduced by Arndt {\it et al} [J. Phys. A {\bf 31} (1998) L45;cond-mat/9809123]. This model exhibits spatial condensation of particles. It has been argued that the model has a phase transition from a ``mixed phase'' to a ``disordered phase''. However, in this paper exact calculations are presented which, we believe, show that in the framework of a grand canonical ensemble there is no such phase transition. An analysis of the fluctuations in the particle density strongly suggests that the same result also holds for the canonical ensemble.Comment: 20 pages, 4 figure