The size, density, and formation of the Orcus-Vanth system in the Kuiper belt

The Kuiper belt object Orcus and its satellite Vanth form an unusual system in the Kuiper belt. Orcus is amongst the largest objects known in the Kuiper belt, but the relative size of Vanth is much larger than that of the tiny satellites of the other large objects. From Hubble Space Telescope observations we find that Orcus and Vanth have different visible colors and that Vanth does not share the water ice absorption feature seen in the infrared spectrum of Orcus. We also find that Vanth has a nearly face-on circular orbit with a period of 9.5393 +-0.0001 days and semimajor axis of 8980+-20 km, implying a system mass of 6.32+- 0.01 X 10^20 kg or 3.8% the mass of dwarf planet Eris. From Spitzer Space Telescope observations we find that the thermal emission is consistent with a single body with diameter 940+-70 km and a geometric albedo of 0.28+-0.04. Assuming equal densities and albedos, this measurements implies sizes of Orcus and Vanth of 900 and 280 km, respectively, and a mass ratio of 33. Assuming a factor of 2 lower albedo for the non-icy Vanth, however, implies sizes of 820 and 640 km and a mass ratio of 2. The measured density depends on the assumed albedo ratio of the two objects but is approximately 1.5+-0.3 g cm^-3$, midway between typical densities measured for larger and for smaller objects. The orbit and mass ratio is consistent with formation from a giant impact and subsequent outward tidal evolution and even consistent with the system having now achieved a double synchronous state. The system can equally well be explained, however, by initial eccentric capture, Kozai cycling which increases the eccentricity and decreases the pericenter of the orbit of Vanth, and subsequent tidal evolution inward.Comment: Submitted to A

Human detection and tracking through temporal feature recognition

The ability to accurately track objects of interest – particularly humans – is of great importance in the fields of security and surveillance. In such scenarios, t he application of accurate, automated human tracking offers benefits over manual supervision. In this paper, recent efforts made to investigate the improvement of automated human detection and tracking techniques through the recognition of person-specific time-varying signatures in thermal video are detailed. A robust human detection algorithm is developed to aid the initialisation stage of a state-of-the art existing tracking algorithm. In addition, coupled with the spatial tracking methods present in this algorithm, the inclusion of temporal signature recognition in the tracking process is shown to improve human tracking results

Risk of Population Extinction from Periodic and Abrupt Changes of Environment

A simulation model of a population having internal (genetic) structure is presented. The population is subject to selection pressure coming from the environment which is the same in the whole system but changes in time. Reproduction has a sexual character with recombination and mutation. Two cases are considered - oscillatory changes of the environment and abrupt ones (catastrophes). We show how the survival chance of a population depends on maximum allowed size of the population, the length of the genotypes characterising individuals, selection pressure and the characteristics of the climate changes, either their period of oscillations or the scale of the abrupt shift.Comment: 8 pages, 25 references, 10 figures; preliminary version to be submitted to Physica

Coagulation Calculations of Icy Planet Formation at 15--150 AU: A Correlation Between the Maximum Radius and the Slope of the Size Distribution for Transneptunian Objects

We investigate whether coagulation models of planet formation can explain the observed size distributions of transneptunian objects (TNOs). Analyzing published and new calculations, we demonstrate robust relations between the size of the largest object and the slope of the size distribution for sizes 0.1 km and larger. These relations yield clear, testable predictions for TNOs and other icy objects throughout the solar system. Applying our results to existing observations, we show that a broad range of initial disk masses, planetesimal sizes, and fragmentation parameters can explain the data. Adding dynamical constraints on the initial semimajor axis of `hot' KBOs along with probable TNO formation times of 10-700 Myr restricts the viable models to those with a massive disk composed of relatively small (1-10 km) planetesimals.Comment: Text: 44 pages, Tables: 5, Figures: 17; Accepted for publication in the Astronomical Journa

Semi-classical Quantization in N=4 Supersymmetric Yang-Mills Theory and Duality

At a generic point in the moduli space of vacua of an N=4 supersymmetric gauge theory with arbitrary gauge group the Higgs force does not cancel the magneto-static force between magnetic monopoles of distinct charge. As a consequence the moduli space of magnetically charged solutions is related in a simple way to those of the SU(2) theory. This leads to a rather simple test of S-duality. On certain subspaces of the moduli space of vacua the forces between distinct monopoles cancel and the test of S-duality becomes more complicated.Comment: 11 pages, plain tex with macro included, one Postscript figure, uses psfig.te

Student experiences and perceptions of compulsory research projects: a veterinary perspective

Background Although research underpins clinical work, many students training to be clinicians are not inherently interested in developing research skills. Aim To characterise and understand veterinary student experiences and perceptions of compulsory research projects. Methods This was an explanatory sequential mixed-methods study, with a questionnaire survey of an entire cohort informing purposive selection for focus group discussions. Student views were triangulated with staff questionnaire data. Results About a third of the cohort felt that the project had not been worthwhile or had not fostered useful skills. Focus group data analysis identified fragility of motivation and lack of clear schemata for the research process as key themes. Students were easily demotivated by typical research challenges and lack of schemata contributed to a poor understanding of the rationale for the project, encouraging highly extrinsic forms of motivation. Triangulation with staff questionnaire data indicated that staff understood students’ challenges, but were more likely than students to consider it to be a valuable learning experience. Conclusions Findings support ongoing curriculum development and emphasise that, to optimise motivation, engagement and learning, students training to be clinicians need a clear rationale for research, based on development of critical inquiry skills as a core clinical competency

The Value of College Graduates to the Scottish Economy

Scotland’s colleges are significant economic institutions in their own right. Their activities help support and sustain employment across the communities that they serve. However, the key contribution that colleges make extends well beyond simply how much they spend or invest in the local economy. Colleges play a crucial role in developing Scotland’s growth potential through enhancing human capital – whether that be providing routes from school to work, further training or university; continuous skills-development (often in conjunction with employers); or re-training people for new opportunities. By developing a more productive workforce and boosting participation, colleges help deliver long-term sustainable and inclusive economic growth. Sustainable growth is more important than ever given the new revenue raising responsibilities of the Scottish Parliament. This study undertakes a detailed assessment of the contribution to Scotland's economy from a cohort of college learners over the eight years 2008/09-2015/16. To do this we assess the costs and benefits to the economy from graduates leaving college with a nationally recognised qualification. We use the Fraser of Allander's macroeconomic model of the Scottish economy to provide a robust estimate of the impact on Gross Domestic Product (GDP), employment and tax revenues. For the period 2008/09-2015/16 graduate cohorts we estimate that: The Scottish economy (as measured by GDP) will be better off by over £20 billion in present value terms (i.e. with future benefits discounted) over the long-term. This corresponds to around an additional £55,000 boost to productivity for the Scottish economy per graduate. The present value of the increase in public sector revenues is estimated to be £6.8 billion. Over the years studied, the total costs to the public sector of investing in these learners through nationally-recognised qualifications was approximately £2.4 billion – just 35% of the cumulative tax revenues generated over the long-term. The investment is estimated to support 13,896 full time equivalent (FTE) jobs in present value terms. The analysis in this report has been conducted by the Fraser of Allander Institute (FAI) at the University of Strathclyde. The report was commissioned by Colleges Scotland. Colleges Scotland asked the FAI to estimate the long-term value to the Scottish economy from graduates of Scotland’s colleges. The technical analysis, methodology and writing of the results was undertaken independently by the FAI, using their detailed macroeconomic model of the Scottish economy to undertake the analysis

Particle production processes in high energy physics

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Fraser of Allander Institute : Economic Commentary [June 2018]

As the financial year draws to a close, it is a good time to reflect on Scotland's economic performance over the past twelve months and perhaps more so, to consider the significant challenges that lie ahead. Little has changed since December's Fraser Economic Commentary on Scotland’s economic performance; there is growth, but the pace is slow with little expectation it will accelerate at any significant rate over the coming three years. As has been well established, increasing productivity has been, and remains, one of Scotland’s key economic challenges