What can we infer about the underlying physics from burst distributions observed in an RMHD simulation ?

We determine that the sizes of bursts in mean-square current density in a reduced magnetohydrodynamic (RMHD)simulation follow power-law probability density function (PDF). The PDFs for burst durations and waiting time between bursts are clearly not exponential and could also be power-law. This suffices to distinguish their behaviour from the original Bak et al. sandpile model which had exponential waiting time PDFs. However, it is not sufficient to distinguish between turbulence, some other SOC-like models, and other red noise sources.Comment: In press, Planetary and Space Science. Proceedings of a session at European Geophysical Society General Assembly, Nice, 200

Power law burst and inter-burst interval distributions in the solar wind: turbulence or dissipative SOC ?

We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval tau for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P(e) and P(T) to be power laws, consistent with self-organised criticality (SOC). We find also a power law form for P(tau) that distinguishes this turbulent cascade from the exponential P(tau) of ideal SOC, but not from some other SOC-like sandpile models. We discuss the implications for the relation between SOC and turbulence.Comment: 3 pages, 1 figure. Submitted to PRL on 25th February 2000. Revised version re-submitted on 9th May 2000. Second revised version submitted Phys. Rev. E on 26th June, 200

Enhancing graduate employability in product design: a case study exploring approaches taken on a BSc Product Design course

Purpose – This paper presents a case study to discuss approaches taken within a traditional undergraduate degree course to embed employability skills, encourage student uptake of sandwich placement and increase graduate prospects. A number of new initiatives are presented, including working with live industrial clients, formally preparing students for placement applications and the introduction of an externally facing student run design consortium. Alongside these new initiatives, details of the existing sandwich year provision are also considered and their effectiveness. Design/methodology/approach – A case study based action research approach presents changes to a specific undergraduate course, measuring the effectiveness over a 4-year period using externally collected national DLHE data and internal student feedback to assess the long-term effects on employability. Findings – The paper considers improvements in the graduate employability over the 4 year period covered, in particular, an increase in the graduate employability from 81%-100% and graduate prospects from 62.5% to 95.2% for sandwich students. Data presented also considers additional student feedback correlating with an increase in their preparedness for employment. Practical implications – The implications of undertaking the changes highlighted within this paper have been relatively straightforward, due to the small incremental nature of the changes and the opportunities available through the agencies within the university, and should be replicable at least in part at other HE institutions. Originality/value – This paper considers the impact of employability initiatives undertaken on a single undergraduate course and how these have affected the employability of graduates over a 4-year period, supported by student feedback both internally and externally through national feedback mechanisms. It is anticipated that this research would be beneficial for informing and guiding the development of employability on other undergraduate programmes

Stellar Encounters with Massive Star-Disk Systems

The dense, clustered environment in which massive stars form can lead to interactions with neighboring stars. It has been hypothesized that collisions and mergers may contribute to the growth of the most massive stars. In this paper we extend the study of star-disk interactions to explore encounters between a massive protostar and a less massive cluster sibling using the publicly available SPH code GADGET-2. Collisions do not occur in the parameter space studied, but the end state of many encounters is an eccentric binary with a semi-major axis ~ 100 AU. Disk material is sometimes captured by the impactor. Most encounters result in disruption and destruction of the initial disk, and periodic torquing of the remnant disk. We consider the effect of the changing orientation of the disk on an accretion driven jet, and the evolution of the systems in the presence of on-going accretion from the parent core.Comment: 11 pages, 10 figures, accepted to Ap

The London Heat Island – surface and air temperature measurements in a park and street gorges

This paper reports results from short-term tests carried out as part of a project to characterize the urban heat island in London. The investigations looked at air temperatures upstream and downstream of a park and the surface and air temperatures within street gorges. It was found that the air in the park was associated with lower mean (0.6°C [1.1°F] less) and peak temperatures (1.1°C [2.0°F] less) compared to residential or shopping streets on either side. The apparent cooling influence of the park extended downstream between 200 and 400 meters (200 to 400 yards). Measurements in four street gorges showed a wide variation in surface temperatures—up to 22°C (40°F)—although 5ºC to 10°C (9ºF to 18°F) was more typical. For a given façade, lighter surfaces were associated with lower temperatures, between 6ºC and 10°C (11ºF and 18°F) cooler. A strong relationship was found between mean gorge surface temperature and the gorge air temperature measured at 6 m (20 ft) (half-gorge height). This was true for both a sunny day and a cloudy day. The results suggest that significant reductions in air temperature may be possible by adjusting the albedo of urban surfaces

Efficacy of a self-help manual in increasing resilience in carers of adults with depression in Thailand

Caring for a person with a mental illness can have adverse effects on caregivers; however, little is known about how best to help such caregivers. The aim of the present study was to examine the efficacy of a cognitive behaviour therapy-guided self-help manual in increasing resilience in caregivers of individuals with depression, in comparison to caregivers who receive routine support only. A randomized, controlled trial was conducted, following CONSORT guidelines, with 54 caregivers allocated to parallel intervention (self-help manual) (n = 27) or control (standard support) (n = 27) groups. Resilience was assessed at baseline, post-test (week 8), and follow up (week 12). Intention-to-treat analyses were undertaken. Repeated-measures ANOVA indicated a significant difference in resilience scores between the three time points, showing a large effect. Pairwise comparisons between intervention and control groups indicated resilience to be significantly different between baseline and post-test, and between baseline and follow up, but not between post-test and follow up. Overall, the intervention group showed a slightly greater increase in resilience over time than the control group; however, the time–group interaction was not significant. Guided self-help is helpful in improving caregivers’ resilience and could be used as an adjunct to the limited support provided to carers by mental health nurses and other clinicians

Searching for Planets in the Hyades. I. The Keck Radial Velocity Survey

We describe a high-precision radial velocity search for jovian-mass companions to main sequence stars in the Hyades star cluster. The Hyades provides an extremely well controlled sample of stars of the same age, the same metallicity, and a common birth and early dynamical environment. This sample allows us to explore the dependence of the process of planet formation on only a single independent variable: the stellar mass. In this paper we describe the survey and summarize results for the first five years.Comment: 8 pages, 3 figures; To appear in the July 2002 issue of The Astronomical Journa

The Decay of Accreting Triple Systems as Brown Dwarf Formation Scenario

We investigate the dynamical decay of non-hierarchical accreting triple systems and its implications on the ejection model as Brown Dwarf formation scenario. A modified chain-regularization scheme is used to integrate the equations of motion, that also allows for mass changes over time as well as for momentum transfer from the accreted gas mass onto the bodies. We integrate an ensemble of triple systems within a certain volume with different accretion rates, assuming several prescriptions of how momentum is transferred onto the bodies. We follow their evolution until the systems have decayed. We analyze the end states and decay times of these systems and determine the fraction of Brown Dwarfs formed, their escape speeds as well as the semi-major axis distribution of the formed Brown Dwarf binaries. We find that the formation probability of Brown Dwarfs depends strongly on the assumed momentum transfer which is related to the motion of the gas. Due to ongoing accretion and consequent shrinkage of the systems, the median escape velocity is increased by a factor of 2 and the binary separations are decreased by a factor of 5 compared with non-accreting systems. Furthermore, the obtained semi-major axis distribution drops off sharply to either side of the median, which is also supported by observations. We conclude that accretion and momentum transfer of accreted gas during the dynamical decay of triple systems is able to produce the observed distribution of close binary Brown Dwarfs, making the ejection model a viable option as Brown Dwarf formation scenario.Comment: 31 pages, 8 figures, accepted for publication in Ap