Discovery of a Binary Centaur

We have identified a binary companion to (42355) 2002 CR46 in our ongoing deep survey using the Hubble Space Telescope's High Resolution Camera. It is the first companion to be found around an object in a non-resonant orbit that crosses the orbits of giant planets. Objects in orbits of this kind, the Centaurs, have experienced repeated strong scattering with one or more giant planets and therefore the survival of binaries in this transient population has been in question. Monte Carlo simulations suggest, however, that binaries in (42355) 2002 CR46 -like heliocentric orbits have a high probability of survival for reasonable estimates of the binary's still-unknown system mass and separation. Because Centaurs are thought to be precursors to short period comets, the question of the existence of binary comets naturally arises; none has yet been definitively identified. The discovery of one binary in a sample of eight observed by HST suggests that binaries in this population may not be uncommon.Comment: 20 pages, 4 figures, 1 table accepted for publication in Icaru

What are the patterns of personal learning environments (PLE) for undergraduate students undertaking degrees in nursing.

This is the Core Paper Abstract submitted for the NET conference September 201

Lithium and Lithium Depletion in Halo Stars on Extreme Orbits

We have determined Li abundances in 55 metal-poor (3.6 < [Fe/H] < -0.7) stars with extreme orbital kinematics. We find the Li abundance in the Li-plateau stars and examine its decrease in low-temperature, low-mass stars. The Li observations are primarily from the Keck I telescope with HIRES (spectral resolution of ~48,000 and median signal-to-noise per pixel of 140). Abundances or upper limits were determined for Li for all the stars with typical errors of 0.06 dex. Our 14 stars on the Li plateau give A(Li) = log N(Li)/N(H) + 12.00 of 2.215 +-0.110, consistent with earlier results. We find a dependence of the Li abundance on metallicity as measured by [Fe/H] and the Fe-peak elements [Cr/H] and [Ni/H], with a slope of ~0.18. We also find dependences of A(Li) with the alpha elements, Mg, Ca, and Ti. For the n-capture element, Ba, the relation between A(Li) and [Ba/H] has a shallower slope of 0.13; over a range of 2.6 dex in [Ba/H], the Li abundance spans only a factor of two. We examined the possible trends of A(Li) with the characteristics of the orbits of our halo stars, but find no relationship with kinematic or dynamic properties. The stars cooler than the Li plateau are separated into three metallicity subsets. The decrease in A(Li) sets in at hotter temperatures at high metallicities than at low metallicities; this is in the opposite sense of the predictions for Li depletion from standard and non-standard models.Comment: 29 pages including 3 tables and 12 figures Accepted by The Astrophysical Journal, for the 1 November 2005 issue, v. 63

Understanding the ecology of the Personally Significant Learning Environment (PSLE): one year on

Background: Personal learning environments (PLE) have been shown to be critical in how students negotiate, manage and experience their learning. Understandings of PLEs are largely restricted by narrow definitions that focus on technology alone. The idea of a PLE is often conflated with virtual learning environments (VLEs). In this presentation, we draw on empirical findings from an international study that spanned four countries. Our findings will be of interest to students, educators, researchers and institutions and will facilitate a more in depth understanding of how to support students to create appropriate PLEs for effectively managing their own learning. Aims: The study aim was to provide in-depth insights into how undergraduate students of nursing manage and experience learning through a range of formal and informal components that comprise the PLE. It is a longitudinal mixed-method study that incorporates two key phases. The first phase will be the focus of this presentation. Research design: The first phase comprised a series of focus groups held at each of four institutions in Australia, England, Scotland, Hong Kong and Canada. Ethical approval was obtained at each individual study site. Recruitment at each site was through student emails, flyers and invitations on eLearning sites. Inclusion criteria were that students needed to be enrolled in an undergraduate degree leading to a nurse registration. An important ethical consideration was that students understood that participation or non-participation would not impact relationships with their academic institutions or study outcomes. Nominal group techniques were used in the focus groups together with providing visual representations of their PLE in the form of a sketch or conceptual map. The themed sticky notes and visual representations were photographed and stored for subsequent analysis. Data were analyzed independently by researchers at each site. This initial analysis was at the broadest level of abstraction in order to identify main emerging categories. Via a series of meetings through voice over IP (VoIP) technologies, investigators were able to employ a process of triangulation to provide and reach a consensus regarding commonalities that appeared from focus groups. Key Findings: Eight groups comprising a total of 46 students took part in focus groups across the four sites. The findings from the focus groups generated a range of different types of data that were organized into three major themes; technologies, learning modalities and influencing factors. Technologies included physical items such as; devices; computers; books; journals; newspapers; and furniture; and virtual technology such as; software; applications; and internet resources. PLEs are influenced by individual learning preferences and the learning contexts that students find themselves in. Participants described how the ways they were expected to learn at university, did not always suit their personal learning preferences. Understanding their own learning style was important to enable an effective PLE and customising learning to suit personal preferences was seen as important. An individual’s PLE is impacted by external, interpersonal and intrapersonal factors. A PLE is influenced by these factors both individually, and by the interplay between the factors. External factors included the physical, built aspects of the environment and the learner’s ambient environment. Intrapersonal factors included attitudes, beliefs, preferences and emotions. Interpersonal factors such as how, when and where participants engaged with others also played a significant role in their PLE. Findings suggest a broader understanding of the term personal learning environment than currently exists. Their PLE was relational and comprised a space with personal meaning and significance to the learner - in support of their educational goals. Current definitions of PLE do not capture the broader understanding identified by this study, we therefore propose a new term: personally significant learning environment

In-line and cascaded DWDM transmission using a 15dB net-gain polarization-insensitive fiber optical parametric amplifier

We demonstrate and characterize polarization-division multiplexed (PDM) DWDM data transmission for the first time in a range of systems incorporating a net-gain polarization-insensitive fiber optical parametric amplifier (PI-FOPA) for loss compensation. The PI-FOPA comprises a modified diversity-loop architecture to achieve 15dB net-gain, and up to 2.3THz (~18nm) bandwidth. Three representative systems are characterized using a 100Gb/s PDM-QPSK signal in conjunction with emulated DWDM neighbouring channels: (a) a 4x75km in-line fiber transmission system incorporating multiple EDFAs and a single PI-FOPA (b) N cascaded PI-FOPA amplification stages in an unlevelled Nx25km recirculating loop arrangement, with no EDFAs used within the loop signal path, and (c) M cascaded PI-FOPA amplification stages as part of an Mx75.6km gain-flattened recirculating loop system with the FOPA compensating for the transmission fiber loss, and EDFA compensation for loop switching and levelling loss. For the 4x75km in-line system (a), we transmit 45x50GHz-spaced signals (‘equivalent’ data-rate of 4.5Tb/s) with average OSNR penalty of 1.3dB over the band at 10−3 BER. For the unlevelled ‘FOPA-only’ 25.2km cascaded system (b), we report a maximum of eight recirculations for all 10x100GHz-spaced signals, and five recirculations for 20x50GHz-spaced signals. For the 75.6km levelled system (c), we achieve eight recirculations for all 20x50GHz signals resulting in a total transmission distance of 604.8km

Effective Critical Exponents for Dimensional Ccrossover and Quantum Systems from an Environmentally Friendly Renormalization Group

Series for the Wilson functions of an ``environmentally friendly'' renormalization group are computed to two loops, for an $O(N)$ vector model, in terms of the ``floating coupling'', and resummed by the Pad\'e method to yield crossover exponents for finite size and quantum systems. The resulting effective exponents obey all scaling laws, including hyperscaling in terms of an effective dimensionality, {d\ef}=4-\gl, which represents the crossover in the leading irrelevant operator, and are in excellent agreement with known results.Comment: 10 pages of Plain Tex, Postscript figures available upon request from [email protected], preprint numbers THU-93/18, DIAS-STP-93-1

Spin-rotor Interpretation of Identical Bands and Quantized Alignment in Superdeformed A ≈\approx 190 Nuclei

The ``identical'' bands in superdeformed mercury, thallium, and lead nuclei are interpreted as examples of orbital angular momentum rotors with the weak spin-orbit coupling of pseudo-$SU(3)$ symmetries and supersymmetries.Comment: 15 pages, revtex 3.0, 7 figures available upon request from [email protected]