442 research outputs found

    Brexit outcome unlikely to satisfy anyone

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    https://www.bu.edu/bostonia/2016/brexit-eu-referendum/Published versio

    The Journal of the Center for Interdisciplinary Teaching and Learning

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    IMPACT: The Journal of the Center for Interdisciplinary Teaching & Learning is a peer-reviewed, biannual online journal that publishes scholarly and creative non-fiction essays about the theory, practice and assessment of interdisciplinary education. Impact is produced by the Center for Interdisciplinary Teaching & Learning at the College of General Studies, Boston University (www.bu.edu/cgs/citl).In this issue, podcasts are looked at as a pedagogical game changer. Using the award-wining podcast Serial as their catalyst, this issue's essayists look at podcast's emerging role in higher education, how multimodal learning can help students find their voices, the podcast's place in the curriculum at a criminal justice college, and how podcasts can inspire students to reflectively assess their own writing. Our reviewers take a critical look at the podcasts Welcome to Night Vale and Revisionist History

    Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation

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    The extended Kepler mission, K2, is now providing photometry of new fields every three months in a search for transiting planets. In a recent study, Foreman-Mackey and collaborators presented a list of 36 planet candidates orbiting 31 stars in K2 Campaign 1. In this contribution, we present stellar and planetary properties for all systems. We combine ground-based seeing-limited survey data and adaptive optics imaging with an automated transit analysis scheme to validate 21 candidates as planets, 17 for the first time, and identify 6 candidates as likely false positives. Of particular interest is K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a 2.23 \pm 0.25 R_Earth planet with T_eq = 272 \pm 15 K and an orbital period of 33 days. We also present two new open-source software packages which enable this analysis. The first, isochrones, is a flexible tool for fitting theoretical stellar models to observational data to determine stellar properties using a nested sampling scheme to capture the multimodal nature of the posterior distributions of the physical parameters of stars that may plausibly be evolved. The second is vespa, a new general-purpose procedure to calculate false positive probabilities and statistically validate transiting exoplanets.Comment: 17 pages, 5 figures, 5 tables, accepted for publication in the Astrophysical Journal. Updated to closely reflect published version in ApJ (2015, 809, 25

    Early Breast Cancer Therapy and Cardiovascular Injury

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    Although recent advances in curative-intent therapies are beginning to produce significant survival gains in early breast cancer, these improvements may ultimately be attenuated by increased risk of long-term cardiovascular mortality. This paper reviews emerging evidence on the cardiovascular effects of breast cancer adjuvant therapy and proposes a new entity that we have labeled the “multiple-hit” hypothesis. The evidence that lifestyle modification, especially exercise therapy, may mitigate these adverse effects is also reviewed. These issues are of considerable practical importance for cardiovascular clinicians, as identification and intervention in those at high risk for cardiovascular complications may reduce a major cause of mortality in women with early breast cancer

    The Effects of Background Pressure on SPT-140 Thruster Performance at Multiple Power Levels

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    NASA's planned Psyche mission is scheduled to launch in 2022 and begin a 3.5-year cruise to the metallic asteroid Psyche, where it would examine this unique body. The baseline spacecraft design is a hybrid of JPL's deep-space heritage subsystems with commercial partner SSL's power, structure, and SPT-140 electric propulsion subsystems. Since the deep-space implementation of the SPT-140 differs from the commercial implementation, primarily in the need for deep power throttling, characterization of the system at lower powers is necessary. One specific area of interest is the sensitivity of thruster performance to background pressure in ground-based test facilities, which can have an impact on the prediction of in-space performance. Measurements of this pressure dependence were performed on a qualification-model SPT-140 thruster over the 0.9-4.5 kW range of interest for the Psyche mission. Thrust sensitivity to pressure, in an absolute sense, was largest at 4.5 kW and decreased with power until there was little-to-no measurable effect at 0.9 kW. In a relative sense, thrust sensitivity was similar at all powers above 0.9 kW with about 2-4% higher thrust measured at 10 Torr than at the lowest operating pressure. Thruster stability margin, examined as a function of magnet current, did not have a strong dependence on facility pressure. Finally, an investigation of low-power operation at the lowest facility pressure showed that a combination of added cathode keeper current and additional cathode propellant flow significantly mitigated the larger negative cathode-to-ground voltages that were observed. These test results, combined with thruster life test results, inform the selection of proper low-power operating conditions for Psyche

    PAndAS in the mist: The stellar and gaseous mass within the halos of M31 and M33

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    Large scale surveys of the prominent members of the Local Group have provided compelling evidence for the hierarchical formation of massive galaxies, revealing a wealth of substructure that is thought to be the debris from ancient and on-going accretion events. In this paper, we compare two extant surveys of the M31-M33 subgroup of galaxies; the Pan-Andromeda Archaeological Survey (PAndAS) of the stellar structure, and a combination of observations of the HI gaseous content, detected at 21cm. Our key finding is a marked lack of spatial correlation between these two components on all scales, with only a few potential overlaps between stars and gas.The paucity of spatial correlation significantly restricts the analysis of kinematic correlations, although there does appear to the HI kinematically associated with the Giant Stellar Stream where it passes the disk of M31. These results demonstrate that that different processes must significantly influence the dynamical evolution of the stellar and HI components of substructures, such as ram pressure driving gas away from a purely gravitational path. Detailed modelling of the offset between the stellar and gaseous substructure will provide a determination of the properties of the gaseous halo of M31 and M33.Comment: 11 pages, 6 figures. Accepted for publication in the Astrophysical Journal. Figure quality reduced. High quality version available at http://www.physics.usyd.edu.au/~gfl/Arxiv_Papers/PAndAS_Mist

    Primary open angle glaucoma due to T377M MYOC: Population mapping of a Greek founder mutation in Northwestern Greece

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    BACKGROUND: Mutations in the MYOC gene have been shown to explain 5% of unrelated primary open angle glaucoma (POAG) in different populations. In particular, the T377M MYOC mutation has arisen at least three separate times in history, in Great Britain, India, and Greece. The purpose of this study is to investigate the distribution of the mutation among different population groups in the northwestern region of Greece. MATERIALS AND METHODS: We explored the distribution of the "Greek" T377M founder mutation in the Epirus region in Northwestern Greece, which could be its origin. Genotyping was performed in POAG cases and controls by PCR amplification of the MYOC gene, followed by digestion with restriction enzyme. Statistical analyses were performed by an exact test, the Kaplan-Meier method and the t-test. RESULTS: In the isolated Chrysovitsa village in the Pindus Mountains, a large POAG family demonstrated the T377M mutation in 20 of 66 family members while no controls from the Epirus region (n = 124) carried this mutation (P < 0.001). Among other POAG cases from Epirus, 2 out of 14 familial cases and 1 out of 80 sporadic cases showed the mutation (P = 0.057). The probability of POAG diagnosis with advancing age among mutation carriers was 23% at age 40, and reached 100% at age 75. POAG patients with the T377M mutation were diagnosed at a mean age of 51 years (SD +/- 13.9), which is younger than the sporadic or familial POAG cases: 63.1 (SD +/- 11) and 66.8 (SD +/- 9.8) years, respectively. CONCLUSIONS: The T377M mutation was found in high proportion in members of the Chrysovitsa family (30.3%), in lower proportion in familial POAG cases (14.2%) and seems rare in sporadic POAG cases (1.2%), while no controls (0%) from the Epirus region carried the mutation. Historical and geographical data may explain the distribution of this mutation within Greece and worldwide

    Bayesian Methods for Exoplanet Science

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    Exoplanet research is carried out at the limits of the capabilities of current telescopes and instruments. The studied signals are weak, and often embedded in complex systematics from instrumental, telluric, and astrophysical sources. Combining repeated observations of periodic events, simultaneous observations with multiple telescopes, different observation techniques, and existing information from theory and prior research can help to disentangle the systematics from the planetary signals, and offers synergistic advantages over analysing observations separately. Bayesian inference provides a self-consistent statistical framework that addresses both the necessity for complex systematics models, and the need to combine prior information and heterogeneous observations. This chapter offers a brief introduction to Bayesian inference in the context of exoplanet research, with focus on time series analysis, and finishes with an overview of a set of freely available programming libraries.Comment: Invited revie

    Snake in the Clouds::a new nearby dwarf galaxy in the Magellanic bridge

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    We report the discovery of a nearby dwarf galaxy in the constellation of Hydrus, between the Large and the Small Magellanic Clouds. Hydrus 1 is a mildy elliptical ultra-faint system with luminosity MVM_V\sim -4.7 and size \sim 50 pc, located 28 kpc from the Sun and 24 kpc from the LMC. From spectroscopy of \sim 30 member stars, we measure a velocity dispersion of 2.7 km/s and find tentative evidence for a radial velocity gradient consistent with 3 km/s rotation. Hydrus 1's velocity dispersion indicates that the system is dark matter dominated, but its dynamical mass-to-light ratio M/L \sim 66 is significantly smaller than typical for ultra-faint dwarfs at similar luminosity. The kinematics and spatial position of Hydrus~1 make it a very plausible member of the family of satellites brought into the Milky Way by the Magellanic Clouds. While Hydrus 1's proximity and well-measured kinematics make it a promising target for dark matter annihilation searches, we find no evidence for significant gamma-ray emission from Hydrus 1. The new dwarf is a metal-poor galaxy with a mean metallicity [Fe/H]=-2.5 and [Fe/H] spread of 0.4 dex, similar to other systems of similar luminosity. Alpha-abundances of Hyi 1 members indicate that star-formation was extended, lasting between 0.1 and 1 Gyr, with self-enrichment dominated by SN Ia. The dwarf also hosts a highly carbon-enhanced extremely metal-poor star with [Fe/H] \sim -3.2 and [C/Fe] \sim +3.0.Comment: submitted to MNRAS; 21 page
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