Ultracold collisions in tight harmonic traps: Quantum defect model and application to metastable helium atoms

We analyze a system of two colliding ultracold atoms under strong harmonic confinement from the viewpoint of quantum defect theory and formulate a generalized self-consistent method for determining the allowed energies. We also present two highly efficient computational methods for determining the bound state energies and eigenfunctions of such systems. The perturbed harmonic oscillator problem is characterized by a long asymptotic region beyond the effective range of the interatomic potential. The first method, which is based on quantum defect theory and is an adaptation of a technique developed by one of the authors (GP) for highly excited states in a modified Coulomb potential, is very efficient for integrating through this outer region. The second method is a direct numerical solution of the radial Schr\"{o}dinger equation using a discrete variable representation of the kinetic energy operator and a scaled radial coordinate grid. The methods are applied to the case of trapped spin-polarized metastable helium atoms. The calculated eigenvalues agree very closely for the two methods, and with those computed self-consistently using the generalized self-consistent method.Comment: 11 pages,REVTEX, text substantially revised, title modifie

Individualised learning approach (the three ‘p’s) for a small to medium enterprise through work based learning

An ongoing challenge for education and training providers is to ensure learners can achieve maximum learning and recognition for their vocational education pathways. The strategy and case to be presented could best be described as the 3 ‘p’s approach to the provision of vocational education and training, that is: I. How we support people in their education and training II. What processes we use to provide education and training? III. The place where the learning opportunities are provided. The aim of this paper is to share an educational and training strategy that has been successfully implemented in an Australian enterprise. The strategy provided education and training for the members of the enterprise in a multidisciplinary manner from a certificate through to a degree outcome, entirely through work-based learning (WBL) pedagogy. The research was conducted with six candidates (employees of the enterprise) through their educational journey applying a range of WBL activities including projects and initiatives to improve processes and performances in the workplace. Each candidate's program involved designing the learning component following an initial phase of review of their previous learning’s and qualifications with a learning advisor. This process was deemed as 'the learning review'. The other component of this phase was to develop a learning plan to encapsulate an area of study or disciplinary process that would be relevant to the individual candidate. This process was deemed as 'the learning journey plan'. The second phase was for each candidate to prepare and undertake a problem based/research led learning activity through one or more workplace project/s with the support of the employer. The final phase involved a structured review and development of a final project report to outline the outcomes and learning’s achieved through the work based projects. The research undertaken included post-program interviews with the six candidates and the General Manager and provided an example of a relatable model for all workplaces as well as education and training provider

Work-based learning: a learning strategy in support of the Australian Qualifications Framework

Purpose – The purpose of this paper is to assess the extent to which work-based learning could potentially improve education and training pathways in Australia. Design/methodology/approach – The paper reviews education and training provision in Australia through a contextualisation of the Australian Qualification Framework (AQF) with work-based learning pedagogy to determine the extent to which it might contribute to improved outcomes for learners. Findings – People seeking to advance their career aspirations can consider the application of work-based learning to support lifelong learning pathways through the AQF. Research limitations/implications – There is a need for further longitudinal studies on the outcomes of work-based learning for organisations, individual learners and education and training institutions. Practical implications – The application of effective WBL approaches has the potential to create a much larger flow of learners from experiential and vocational backgrounds into undergraduate programmes and onto higher education programmes using a consistent and effective pedagogy. Social implications – By actively considering the opportunities for learning at work and through work learners, educators and business managers may recognise that there would be more demand for work-based learning. Originality/value – This paper represents an initial action research study which examines the role WBL can provide for life-long learning

An FFAG Transport Line for the PAMELA Project

The PAMELA project to design an accelerator for hadron therapy using non-scaling Fixed Field Alternating Gradient (NS-FFAG) magnets requires a transport line and gantry to take the beam to the patient. The NS-FFAG principle offers the possibility of a gantry much smaller, lighter and cheaper than conventional designs, with the added ability to accept a wide range of fast changing energies. This paper will build on previous work to investigate a transport line which could be used for the PAMELA project. The design is presented along with a study and optimisation of its acceptance

Effects of Elevated pCO2 and Irradiance on Growth, Photosynthesis and Calcification in Halimeda discoidea

Ocean acidification (OA) effects on photophysiology and calcification were examined in Halimeda discoidea, a calcifying macroalga that produces tropical reef sediments. Photosynthetic parameters, including maximum photosynthetic rate (Pmax), photosynthetic efficiency (α) and compensating irradiance (Ic) were determined in short-term assays on live thalli after a 10 d exposure to 4 levels of CO2 partial pressures (pCO2; 491, 653, 982 and 1201 µatm) under saturating (300 µmol photons m-2 s-1) and sub-saturating (90 µmol photons m-2 s-1) irradiance in an aquaria study. Morphology of aragonite crystals produced in segments formed on adult thalli was characterized using scanning electron microscopy (SEM). Further, we examined crystal morphology and changes in inorganic content of non-living segments exposed to elevated (1201 µatm) and ambient pCO2 for 27 d to assess OA effects on carbonate sediments generated from H. discoidea. Even though Pmax was higher under elevated pCO2, this photophysiological response did not result in higher calcification rates. Based on crystal measurements and SEM imagery, aragonite crystals within new segments were indistinguishable across pCO2 and irradiance treatments. Under high irradiance, new segments showed a greater investment in organic versus inorganic production. Non-living segments contained narrower crystals after 27 d exposure to elevated pCO2 relative to controls, but differences were small (0.03 µm) and did not contribute significantly to changes in normalized biomass or inorganic content. Based on these results, H. discoidea will likely produce new calcified segments with intact aragonite crystals under year 2100 pCO2 levels at high and low irradiance, while aragonite crystals of the sediment may produce thinner needle carbonate muds

Data-driven unsupervised clustering of online learner behaviour

The widespread adoption of online courses opens opportunities for analysing learner behaviour and optimising web-based learning adapted to observed usage. Here we introduce a mathematical framework for the analysis of time series of online learner engagement, which allows the identification of clusters of learners with similar online temporal behaviour directly from the raw data without prescribing a priori subjective reference behaviours. The method uses a dynamic time warping kernel to create a pairwise similarity between time series of learner actions, and combines it with an unsupervised multiscale graph clustering algorithm to identify groups of learners with similar temporal behaviour. To showcase our approach, we analyse task completion data from a cohort of learners taking an online post-graduate degree at Imperial Business School. Our analysis reveals clusters of learners with statistically distinct patterns of engagement, from distributed to massed learning, with different levels of regularity, adherence to pre-planned course structure and task completion. The approach also reveals outlier learners with highly sporadic behaviour. A posteriori comparison against student performance shows that, whereas high performing learners are spread across clusters with diverse temporal engagement, low performers are located significantly in the massed learning cluster, and our unsupervised clustering identifies low performers more accurately than common machine learning classification methods trained on temporal statistics of the data. Finally, we test the applicability of the method by analysing two additional datasets: a different cohort of the same course, and time series of different format from another university

Flight tests of IFR landing approach systems for helicopters

Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed

Relativistic fine structure oscillator strengths for Li-like ions: C IV - Si XII, S XIV, Ar XVI, Ca XVIII, Ti XX, Cr XXII, and Ni XXVI

Ab initio calculations including relativistic effects employing the Breit-Pauli R-matrix (BPRM) method are reported for fine structure energy levels and oscillator strengths upto n = 10 and 0.leq. l .leq.9 for 15 Li-like ions: C IV, N V, O VI, F VII, Ne VIII, Na IX, Mg X, Al XI, Si XII, S XIV, Ar XVI, Ca XIII, Ti XX, Cr XXII, and Ni XXVI. About one hundred bound fine structure energy levels of total angular momenta, 1/2 .leq. J .leq. 17/2 of even and odd parities, total orbital angular momentum, 0 .leq L .leq. 9 and spin multiplicity (2S+1) = 2, 4 are considered for each ion. The levels provide almost 900 dipole allowed and intercombination bound-bound transitions. The BPRM method enables consideration of large set of transitions with uniform accuracy compared to the best available theoretical methods. The CC eigenfunction expansion for each ion includes the lowest 17 fine structure energy levels of the core configurations 1s^2, 1s2s, 1s2p, 1s3s, 1s3p, and 1s3d. The calculated energies of the ions agree with the measured values to within 1% for most levels. The transition probabilities show good agreement with the best available calculated values. The results provide the largest sets of energy levels and transition rates for the ions and are expected to be useful in the analysis of X-ray and EUV spectra from astrophysical sources.Comment: 16 pgs., to appear in Astronomy and Astrophysic