Two monopoles of one type and one of another

The metric on the moduli space of charge (2,1) SU(3) Bogomolny-Prasad-Sommerfield monopoles is calculated and investigated. The hyperKahler quotient construction is used to provide an alternative derivation of the metric. Various properties of the metric are derived using the hyperKahler quotient construction and the correspondence between BPS monopoles and rational maps. Several interesting limits of the metric are also considered.Comment: 48 pages, LaTeX, 2 figures. Typos corrected. Version in JHE

Coexistence of OFDM and FBMC for Underlay D2D Communication in 5G Networks

Device-to-device (D2D) communication is being heralded as an important part of the solution to the capacity problem in future networks, and is expected to be natively supported in 5G. Given the high network complexity and required signalling overhead associated with achieving synchronization in D2D networks, it is necessary to study asynchronous D2D communications. In this paper, we consider a scenario whereby asynchronous D2D communication underlays an OFDMA macro-cell in the uplink. Motivated by the superior performance of new waveforms with increased spectral localization in the presence of frequency and time misalignments, we compare the system-level performance of a set-up for when D2D pairs use either OFDM or FBMC/OQAM. We first demonstrate that inter-D2D interference, resulting from misaligned communications, plays a significant role in clustered D2D topologies. We then demonstrate that the resource allocation procedure can be simplified when D2D pairs use FBMC/OQAM, since the high spectral localization of FBMC/OQAM results in negligible inter-D2D interference. Specifically, we identify that FBMC/OQAM is best suited to scenarios consisting of small, densely populated D2D clusters located near the encompassing cell's edge.Comment: 7 pages, 9 figures, Accepted at IEEE Globecom 2016 Workshop

A Multi-Survey Approach to White Dwarf Discovery

By selecting astrometric and photometric data from the Sloan Digital Sky Survey (SDSS), the L{\'e}pine & Shara Proper Motion North Catalog (LSPM-North), the Two Micron All Sky Survey (2MASS), and the USNO-B1.0 catalog, we use a succession of methods to isolate white dwarf candidates for follow-up spectroscopy. Our methods include: reduced proper motion diagram cuts, color cuts, and atmospheric model adherence. We present spectroscopy of 26 white dwarfs obtained from the CTIO 4m and APO 3.5m telescopes. Additionally, we confirm 28 white dwarfs with spectra available in the SDSS DR7 database but unpublished elsewhere, presenting a total of 54 WDs. We label one of these as a recovered WD while the remaining 53 are new discoveries. We determine physical parameters and estimate distances based on atmospheric model analyses. Three new white dwarfs are modeled to lie within 25 pc. Two additional white dwarfs are confirmed to be metal-polluted (DAZ). Follow-up time series photometry confirms another object to be a pulsating ZZ Ceti white dwarf.Comment: 9 figures, 3 Tables; http://stacks.iop.org/1538-3881/143/10

Titan's Surface Temperatures from Cassini CIRS

The surface brightness temperature of Titan can be measured from Cassini through a spectral window at 19 microns where the atmosphere is low in opacity. The Composite Infrared Spectrometer (CIRS) on Cassini observes this wavelength in its far-infrared channel. Because the Cassini tour has provided global coverage and a range of viewing geometries, CIRS has been able to go beyond the earlier flyby results of Voyager IRIS Near the equator, CIRS measures the zonally-averaged surface brightness temperature to be 917 K, very close to the temperature found at the surface by Huygens. Latitude maps show that Titan's surface temperatures drop off by about 2 K toward the south and by about 3 K toward the north. This temperature distribution is consistent with Titan's late northern winter when the data were taken. As the seasons progress, CIRS is continuing to search for corresponding changes in the temperatures of the surface and lower atmosphere. CIRS is also extending global mapping to both latitude and longitude to look for correlations between surface temperatures and geological features

50 Years of Spaceflight with Fourier Transform Spectrometers (FTS) Built at NASA GSFC

Over the past 50 years, NASA Goddard Space Flight Center (GSFC) has been developing, building, testing and flying a series of Fourier Transform Spectrometers (FTS). This began with the IRIS instruments on the Earth-orbiting Nimbus satellites and progressed to more sophisticated designs optimized for interplanetary spacecraft sent to Mars and later to the outer solar system. Adaptions have been made over time, including progressively higher spectral resolution, sensitivity, numbers of detectors and complexity. Instrument operating temperatures have decreased to enable remote sensing of the cold giant planet systems. In this paper we describe the historical evolution of this instrument line, comparing and contrasting different aspects such as optical design and materials, detector types and data handling. We conclude by looking towards the future. At present the CIRS-Lite prototype is being tested at NASA GSFC for potential use on a future mission to the ice giants, Uranus and Neptune. Surpassing the previous performance of the Voyager IRIS instruments remains challenging, and new technologies that could enable these measurements are discussed