332 research outputs found
Using distributional similarity to organise biomedical terminology
We investigate an application of distributional similarity techniques to the problem of structural organisation of biomedical terminology. Our application domain is the relatively small GENIA corpus. Using terms that have been accurately marked-up by hand within the corpus, we consider the problem of automatically determining semantic proximity. Terminological units are dened for our purposes as normalised classes of individual terms. Syntactic analysis of the corpus data is carried out using the Pro3Gres parser and provides the data required to calculate distributional similarity using a variety of dierent measures. Evaluation is performed against a hand-crafted gold standard for this domain in the form of the GENIA ontology. We show that distributional similarity can be used to predict semantic type with a good degree of accuracy
The Green Wave of Electrification: Systems Solution to the Energy Challenges Facing the U.S.
Atlanta Conference on Science and Innovation Policy 2009This presentation was part of the session : Achieving National and Global GoalsIEEE-US
Laudato Siâ and the Consumption Challenge: Giving Students a Visceral Exercise in Saving Our Planet
Laudato Siâ is arguably the most comprehensive, powerful, and influential manifesto in the canon of environment stewardship. Pope Francis calls for nothing short of upending our consumer culture in the service of saving the planet. Gandhiâs plea to âlive simply so that others may simply liveâ is the Popeâs ultimate admonition in his encyclical and the essence of his call to action on behalf of human survival. The following discussion highlights an innovative and powerful classroom experience pioneered in one of Regis Universityâs capstone interdisciplinary seminars. The transformational learning outcomes of this Consumption Challenge (the name of the assignment) eclipsed all reasonable expectations and delivered to its students a visceral connection to what Pope Francis is asking from us in Laudato Siâ. Furthermore, the basic structure of this experiential course assignment can be used across all disciplines in Jesuit higher education. The authors offer this exercise as a tested and proven vehicle for bringing to our students the critical hopes, expectations, and personal challenges of the Popeâs historic encyclical
A Glimpse at Quasar Host Galaxy Far-UV Emission, Using DLAs as Natural Coronagraphs
In merger-driven models of massive galaxy evolution, the luminous quasar
phase is expected to be accompanied by vigorous star formation in quasar host
galaxies. In this paper, we use high column density Damped Lyman Alpha (DLA)
systems along quasar sight lines as natural coronagraphs to directly study the
far-UV (FUV) radiation from the host galaxies of luminous background quasars.
We have stacked the spectra of 2,000 DLA systems (N_HI>10^{20.6} cm^{-2})
with a median absorption redshift = 2.6 selected from quasars observed in
the SDSS-III Baryon Oscillation Spectroscopic Survey. We detect residual flux
in the dark troughs of the composite DLA spectra. The level of this residual
flux significantly exceeds systematic errors in the SDSS fiber sky subtraction;
furthermore, the residual flux is strongly correlated with the continuum
luminosity of the background quasar, while uncorrelated with DLA column density
or metallicity. We conclude that the flux could be associated with the average
FUV radiation from the background quasar host galaxies (with medium redshift <
z > = 3.1) that is not blocked by the intervening DLA. Assuming all of the
detected flux originates from quasar hosts, for the highest quasar luminosity
bin (= 2.5x 10^{13} L_sun), the host galaxy has a FUV intensity of 1.5 +/-
0.2 x 10^{40} erg s^{-1} A^{-1}; this corresponds to an unobscured UV star
formation rate of 9 M_sun/yr.Comment: 15 pages, 10 figures, Accepted for publication in Ap
Using Local Knowledge, Hydrologic, and Climate Data to Develop a Driftwood Harvest Model in Interior Alaska
Many rural Alaska residents rely on harvested driftwood from the Yukon River for fuel and construction materials, however they have stated that the character of the summer discharge in the Yukon River is changing and affecting their ability to harvest this resource. We examined whether the perceived changes in driftwood availability are related to changes in river hydrology and how changes in hydrology may affect future driftwood flows and the livelihoods of rural Alaskans.IAB, NSF, RAP, WERC, Alaska APSCo
A glimpse at quasar host galaxy Far-UV emission using damped Lyα's as natural coronagraphs
In merger-driven models of massive galaxy evolution, the luminous quasar phase is expected to be accompanied by vigorous star formation in quasar host galaxies. In this paper, we use high column density damped Lyα (DLA) systems along quasar sight lines
Phonons, electronic charge response and electron-phonon interaction in the high-temperature superconductors
We investigate in the framework of linear response theory the complete phonon
dispersion, phonon induced electronic charge response, electron-phonon
interaction and dielectric and infrared properties of the high-temperature
superconductors (HTSC's). In particular the experimentally observed strong
renormalization of the in-plane oxygen bond-stretching modes (OBSM) which
appear upon doping in the HTSC's is discussed. It is shown that the
characteristic softening, indicating a strong EPI, is most likely a generic
effect of the CuO plane and is driven by a nonlocal coupling of the displaced
ions to the localized charge-fluctuations (CF's) at the Cu and O ions. The
different behaviour of the OBSM during the insulator-metal transition via the
underdoped phase is calculated and from a comparison of these modes conclusions
about the electronic state in the HTSC's are drawn. The underdoped state is
modelled in terms of a charge response which is insulator-like at the Cu and is
competing with a metallic charge response at the O-network in the CuO plane.
For the non-cuprate HTSC Ba-Bi-O also a strong renormalization of the OBSM is
predicted. C-axis polarized infrared and Raman-active modes of the HTSC's are
calculated in terms of CF's and anisotropic dipole-fluctuations and the problem
of a metallic character of the BiO planes is studied.Interlayer phonons and
their accompanying charge response are investigated. Depending on the
interlayer coupling calculations are performed from the static, adiabatic- to
the non-adiabatic regime.It is shown that phonon-plasmon mixing and a strong
long-ranged non-adiabatic EPI becomes evident within a certain region around
the c-axis. Both the OBSM and the non-adiabatic coupled c-axis phonon-plasmon
modes are found to be important for pairing in the HTSC's.Comment: 65 pages,20 figures. Extended version to appear in Physica Status
Solidi (b) 2004; figure 20 has been corrected; references have been adde
Progress in Spacecraft Environment Interactions: International Space Station (ISS) Development and Operations
The set of spacecraft interactions with the space flight environment that have produced the largest impacts on the design, verification, and operation of the International Space Station (ISS) Program during the May 2000 to May 2007 time frame are the focus of this paper. In-flight data, flight crew observations, and the results of ground-based test and analysis directly supporting programmatic and operational decision-making are reported as are the analysis and simulation efforts that have led to new knowledge and capabilities supporting current and future space explorations programs. The specific spacecraft-environment interactions that have had the greatest impact on ISS Program activities during the first several years of flight are: 1) spacecraft charging, 2) micrometeoroids and orbital debris effects, 3) ionizing radiation (both total dose to materials and single event effects [SEE] on avionics), 4) hypergolic rocket engine plume impingement effects, 5) venting/dumping of liquids, 6) spacecraft contamination effects, 7) neutral atmosphere and atomic oxygen effects, 8) satellite drag effects, and 9) solar ultraviolet effects. Orbital inclination (51.6deg) and altitude (nominally between 350 km and 460 km) determine the set of natural environment factors affecting the performance and reliability of materials and systems on ISS. ISS operates in the F2 region of Earth s ionosphere in well-defined fluxes of atomic oxygen, other ionospheric plasma species, solar UV, VUV, and x-ray radiation as well as galactic cosmic rays, trapped radiation, and solar cosmic rays. The micrometeoroid and orbital debris environment is an important determinant of spacecraft design and operations in any orbital inclination. The induced environment results from ISS interactions with the natural environment as well as environmental factors produced by ISS itself and visiting vehicles. Examples include ram-wake effects, hypergolic thruster plume impingement, materials out-gassing, venting and dumping of fluids, and specific photovoltaic (PV) power system interactions with the ionospheric plasma. Vehicle size (L) and velocity (v), combined with the magnitude and direction of the geomagnetic field (B) produce operationally significant magnetic induction voltages (VxB.L) in ISS conducting structure during high latitude flight (>+/- 45deg) during each orbit. In addition, ISS is a large vehicle and produces a deep wake structure from which both ionospheric plasma and neutrals species are largely excluded. ISS must fly in a very limited number of approved flight attitudes, so that exposure of a particular material or system to environmental factors depends upon: 1) location on ISS, 2) ISS flight configuration, 3) ISS flight attitude, and 4) variation of solar exposure (Beta angle), and hence thermal environment, with time. Finally, an induced ionizing radiation environment is produced by trapped radiation and solar/cosmic ray interactions with the relatively massive ISS structural shielding
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