Electromagnetic energy transfer and switching in nanoparticle chain arrays below the diffraction limit

Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners (bending radius much less than wavelength of visible light). Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale ≪1 μm

Self-similar solutions of semilinear wave equations with a focusing nonlinearity

We prove that in three space dimensions a nonlinear wave equation $u_{tt}-\Delta u = u^p$ with $p\geq 7$ being an odd integer has a countable family of regular spherically symmetric self-similar solutions.Comment: 12 pages, 3 figures, minor corrections to match the published versio

A journey through interprofessional education: Students’ perspectives of teamwork in a transforming curriculum

Background. Student engagement in curricular transformation is topical at the University of Cape Town (UCT), including in its Faculty of Health Sciences (FHS). Teamwork, which is essential to contemporary interprofessional healthcare, is an objective of transformative health sciences education. This study offers a contemporary contribution from the perspective of students to earlier work on shared learning at UCT FHS. Objectives. There is a paucity of research literature on this study’s target population. Therefore, a qualitative design was used to explore first-year health sciences students’ perceptions and experiences of teamwork within an undergraduate shared learning programme. Methods. The primary data collection method was focus group discussion. Two additional qualitative methods, free-listing and pile-sorting, were used to expand upon data collected in the focus groups. Results were analysed thematically. Results. The study sample (N=32) included first-year audiology, medical, occupational therapy, physiotherapy, and speech and language pathology students. The findings revealed that although their experiences of teamwork varied, students had a comprehensive perception of what teamwork entailed in their educational context. Therefore, the findings were used to generate a heuristic for teamwork learning for undergraduate health sciences students. Conclusion. The study positions students to contribute tangibly to the curricular transformation process at their university. Students’ perspectives of teamwork may be useful in the future design and delivery of entry-level interprofessional courses aiming to instil teamwork skills

Life-cycle of the European compost worm Dendrobaena veneta (Oligochaeta)

The life-cycle of Dendrobaena veneta was studied to assess the potential of this species in vermiculture. The development, growth and reproduction were investigated by rearing worms at 25°C on urine-free cattle manure with a moisture content of 80% over a period of 200 days. It was found that cocoons are produced at a mean rate of 0,28 cocoons per worm per day and production can be sustained for at least 200 days. The mean incubation period of the cocoons is 42,1 days with a very low hatching success. The mean number of hatchlings per cocoon that hatched was 1,1. Sexual maturity may be attained within 20 to 35 days but some worms take up to 130 days. Dendrobaena veneta grew well on cattle manure. This species seems to be less suitable than some other epigeic species for vermiculture, at least in terms of its reproductive capacity in the experimental climatic conditions

The last Gift of BeppoSAX: PDS Observations of the two Blazars 1ES 0507-040 and PKS 1229-021

Towards the end of the BeppoSAX mission, the only operated Narrow Field Instrument was the PDS, which covers the energy range 13-300 keV. Two blazars, 1ES 0507-040 (z=0.304) and PKS 1229-021 (z= 1.045), suitably located in the sky for BeppoSAX pointing, were observed for about 2 days each in Spring 2002 with the PDS and detected up to 50 keV. 1ES0507-040 had been already observed by the BeppoSAX NFIs at an earlier epoch for a much shorter time. We have re-analysed those data as well, and identified a possible contamination problem in the PDS spectrum. We present our recent PDS data on both sources, combined with the previous BeppoSAX data and with non-simultaneous observations at other frequencies. The derived Spectral Energy Distributions allow us to discuss the origin of the high energy component.Comment: 4 pages, 6 figures, poster presented at the symposium: The Restless High-Energy Universe, Amsterdam, May 200

The HATNet and HATSouth Exoplanet Surveys

The Hungarian-made Automated Telescope Network (HATNet) has been in operation since 2003, with the key science goal being the discovery and accurate characterization of transiting extrasolar planets (TEPs) around bright stars. Using six small, 11\,cm\ aperture, fully automated telescopes in Arizona and Hawaii, as of 2017 March, it has discovered and accurately characterized 67 such objects. The HATSouth network of telescopes has been in operation since 2009, using slightly larger, 18\,cm diameter optical tubes. It was the first global network of telescopes using identical instrumentation. With three premier sites spread out in longitude (Chile, Namibia, Australia), the HATSouth network permits round-the-clock observations of a 128 square arcdegree swath of the sky at any given time, weather permitting. As of this writing, HATSouth has discovered 36 transiting exoplanets. Many of the altogether ~100 HAT and HATSouth exoplanets were the first of their kind. They have been important contributors to the rapidly developing field of exoplanets, motivating and influencing observational techniques, theoretical studies, and also actively shaping future instrumentation for the detection and characterization of such objects.Comment: Invited review chapter, accepted for publication in "Handbook of Exoplanets", edited by H.J. Deeg and J.A. Belmonte, Springer Reference Work

Secular spin-down of the AMP XTE J1751-305

Context. Of the 13 known accreting millisecond pulsars, only a few showed more than one outburst during the RXTE era. XTE J1751-305 showed, after the main outburst in 2002, other three dim outbursts. We report on the timing analysis of the latest one, occurred on October 8, 2009 and serendipitously observed from its very beginning by RXTE. Aims. The detection of the pulsation during more than one outburst permits to obtain a better constraint of the orbital parameters and their evolution as well as to track the secular spin frequency evolution of the source. Methods. Using the RXTE data of the last outburst of the AMP XTE J1751-305, we performed a timing analysis to improve the orbital parameters. Because of the low statistics, we used an epoch folding search technique on the whole data set to improve the local estimate of the time of ascending node passage. Results. Using this new orbital solution we epoch folded data obtaining three pulse phase delays on a time span of 1.2 days, that we fitted using a constant spin frequency model. Comparing this barycentric spin frequency with that of the 2002 outburst, we obtained a secular spin frequency derivative of -0.55(12) x 10^{-14} Hz s^{-1}. In the hypothesis that the secular spin-down is due to a rotating magneto-dipole emission, consistently with what is assumed for radio pulsars, we estimate the pulsar's magnetic dipole value. We derive an estimate of the magnetic field strength at the polar cap of B_{PC} = 4.0(4) x 10^8 Gauss, for a neutron star mass of 1.4M\odot, assuming the Friedman Pandharipande Skyrme equation of state.Comment: 7 pages, 4 figures, accepted for publication on A&

Projected Impact of Visitor Limitations in Glacier National Park

With consistently increasing visitor numbers in Glacier National Park (GNP), park managers are working to come up with management solutions for transportation, visitation, visitor use, trails, and access within the Going-to-the-Sun Road (GTSR) corridor during peak season. The GTSR Corridor Management Plan Environmental Assessment was developed in September, 2019. The preferred alternative included in the assessment is an adaptive management approach to address visitation levels, which includes strategies such as expanding the shuttle system, adding hiking and biking trails, and some changes to parking availability in various areas. The objective of this study is to provide a review of various reservation systems used in other protected areas to address visitation levels, and gain an understanding of what the impact may be to areas around the park if a visitation cap or restricted access is enacted by GNP management