Community indicators: a framework for observing and supporting community activity on Cloudworks

Cloudworks (Cloudworks.ac.uk) is a social networking site designed for sharing, finding and discussing learning and teaching ideas and experiences. Design and development of the site has been based on an iterative analysis, development and implementation approach, underpinned by ongoing research and evaluation. To this end, we have been seeking to establish strategies to enable us to systematically position transactions and emerging patterns of activity on the site so that we can more reliably use the empirical evidence we have gathered (Galley, 2009a, Galley 2009b, Alevizou et al., 2010a, Conole et al, 2010). In this paper we will introduce a framework we have developed for observing and supporting community development on the site. In building our framework we have used empirical evidence gathered from the site, then related it to the literature from a range of disciplines concerned with professional and learning communities. We link research relating to distance learning communities with studies into Computer Mediated Communication (CMC), self-organising communities on the web, and wider research about the nature of learning organisations and continuous professional development. We argue that this framework can be used to capture the development of productive communities in the space (i.e. how far cohesive, productive groups can be said to be emerging or not) and also help focus futur

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Application of miniature heart rate data loggers for use in large free-moving decapod crustaceans: Method development and validation

Cardiovascular responses of decapod crustaceans to environmental challenges have received extensive attention. However, nearly all of these studies have been restricted to lab-based experiments; here we describe a methodology that will enable measurement of heart rate (HR) in free-moving decapods in the field. Data storage tag heart rate and temperature loggers (DST micro-HRT; Star-Oddi) were used to record electrocardiograms (ECG) and HR in large decapod crustaceans. These loggers were originally designed for use in vertebrates and must be surgically implanted in the body cavity near the heart in order to function. We adapted these loggers for external use in large decapod crustaceans. The method involved abrading the carapace directly above the heart and placing the electrodes of the logger directly on top of the dermal tissue. The loggerwas then secured in place with periphery wax. This method negated some of the more intricate operations used for vertebrates. The rapid setup time of approximately 5 min suggested that animals could be easily instrumented in the field and without the use of anesthetic. The logger was calibrated by simultaneously measuring theHRchanges of aWest Indianspider crabMith