155 research outputs found
Ranking algorithms for implicit feedback
This report presents novel algorithms to use eye movements as an implicit relevance feedback in order to improve the performance of the searches. The algorithms are evaluated on "Transport Rank Five" Dataset which were previously collected in Task 8.3. We demonstrated that simple linear combination or tensor product of eye movement and image features can improve the retrieval accuracy
Adaptive sampling in context-aware systems: a machine learning approach
As computing systems become ever more pervasive, there is an increasing need for them to understand and adapt to the state of the environment around them: that is, their context. This understanding comes with considerable reliance on a range of sensors. However, portable devices are also very constrained in terms of power, and hence the amount of sensing must be minimised. In this paper, we present a machine learning architecture for context awareness which is designed to balance the sampling rates (and hence energy consumption) of individual sensors with the significance of the input from that sensor. This significance is based on predictions of the likely next context. The architecture is implemented using a selected range of user contexts from a collected data set. Simulation results show reliable context identification results. The proposed architecture is shown to significantly reduce the energy requirements of the sensors with minimal loss of accuracy in context identification
A Near-Total Decline in Caribou on Prince of Wales, Somerset, and Russell Islands, Canadian Arctic
The number of caribou (Rangifer tarandus) on Prince of Wales, Somerset, and Russell islands in the south-central Canadian Arctic declined by 98% in 15 years, from an estimated 6048 (16% calves) in 1980 to an estimated 100 (0% calves) in 1995. Those estimates were obtained by systematic aerial surveys that used the same design and methods and comparable survey coverage. We do not have the data needed to determine the rate of decrease between 1980 and 1995 or its possible causes. There is no evidence for large-scale winter mortality in any one year or few consecutive years. A probable explanation for the decline is consequential reductions in long-term survival rates, both of breeding females and of calves in their first year of life, associated with continued caribou harvesting and markedly increased wolf (Canis lupus) predation on the dwindling number of caribou through the 1980s and early 1990s. The delay in detecting the decline and the lack of understanding of its causes will handicap the development of an ecologically sound recovery plan. As previous caribou declines have been followed by recovery, some comfort may be drawn from the likelihood of unaided recovery. However, the number of caribou has declined to the point where recovery will be tenuous and lengthy, at best. Unaided recovery could easily fail to occur, so we should not be complacent, especially as extirpation of these few remaining caribou would remove a distinct genetic group and reduce the biodiversity of caribou on Canadaâs Arctic Islands.Le nombre de caribous (Rangifer tarandus) se trouvant sur les Ăźles Prince of Wales, Somerset et Russell, dans le centresud de lâArctique canadien, a chutĂ© de 98 % en 15 ans, passant dâun nombre estimĂ© Ă 6 048 (dont 16 % Ă©taient des veaux) en 1980 Ă un nombre estimĂ© Ă 100 (dont aucun veau) en 1995. Ces estimations ont Ă©tĂ© obtenues au moyen de relevĂ©s aĂ©riens systĂ©matiques recourant aux mĂȘmes dĂ©finitions, aux mĂȘmes mĂ©thodes et Ă des aires de relevĂ©s comparables. On ne possĂšde pas les donnĂ©es nĂ©cessaires pour dĂ©terminer le taux de diminution entre 1980 et 1995 ou les causes possibles de cette diminution. Par ailleurs, rien nâindique quâun taux de mortalitĂ© hivernal Ă©levĂ© a Ă©tĂ© enregistrĂ© pendant une annĂ©e quelconque ou pendant quelques annĂ©es de suite. Il se peut que le dĂ©clin du nombre de caribous enregistrĂ© dans les annĂ©es 1980 et au dĂ©but des annĂ©es 1990 soit attribuable aux rĂ©ductions correspondantes des taux de survie Ă long terme chez les femelles de reproduction et les veaux pendant leur premiĂšre annĂ©e de vie, le tout jumelĂ© au prĂ©lĂšvement continuel des caribous ainsi quâĂ la prĂ©dation grandement accrue des caribous par les loups (Canis lupus). Le retard Ă dĂ©tecter ce dĂ©clin et le manque de comprĂ©hension de ses causes pourront nuire Ă lâĂ©laboration dâun plan de rĂ©cupĂ©ration solide du point de vue Ă©cologique. Puisque les dĂ©clins prĂ©cĂ©dents de caribous ont Ă©tĂ© suivis de rĂ©cupĂ©ration, on peut se consoler en se disant quâil est possible que la rĂ©cupĂ©ration se fasse spontanĂ©ment. Cependant, le nombre de caribous a chutĂ© au point oĂč la rĂ©cupĂ©ration sera longue et difficile, mĂȘme dans le meilleur des cas. Il se peut quâil nây ait pas de rĂ©cupĂ©ration spontanĂ©e et par consĂ©quent, on ne devrait pas se contenter de cette situation, surtout puisque lâextirpation des quelques caribous qui restent pourrait Ă©liminer un groupe gĂ©nĂ©tique distinct et rĂ©duire la biodiversitĂ© du caribou dans lâarchipel Arctique canadien
An interdisciplinary approach to identify adaptation strategies that enhance flood resilience and urban liveability
Extinction in Star-Forming Disk Galaxies from Inclination-Dependent Composite Spectra
Extinction in galaxies affects their observed properties. In scenarios
describing the distribution of dust and stars in individual disk galaxies, the
amplitude of the extinction can be modulated by the inclination of the
galaxies. In this work we investigate the inclination dependency in composite
spectra of star-forming disk galaxies from the Sloan Digital Sky Survey Data
Release 5. In a volume-limited sample within a redshift range 0.065-0.075 and a
r-band Petrosian absolute magnitude range -19.5 to -22 which exhibits a flat
distribution of inclination, the inclined relative to face-on extinction in the
stellar continuum is found empirically to increase with inclination in the g,
r, and i bands. Within the central 0.5 intrinsic half-light radius of the
galaxies, the g-band relative extinction in the stellar continuum for the
highly-inclined objects (axis ratio b/a = 0.1) is 1.2 mag, agreeing with
previous studies. The extinction curve of the disk galaxies is given in the
restframe wavelengths 3700-8000 angstrom, identified with major optical
emission and absorption lines in diagnostics. The Balmer decrement remains
constant with inclination, suggesting a different kind of dust configuration
and/or reddening mechanism in the HII region from that in the stellar
continuum. One factor is shown to be the presence of spatially non-uniform
interstellar extinction, presumably caused by clumped dust in the vicinity of
the HII region.Comment: To appear in the Astrophysical Journa
Understanding the Astrophysics of Galaxy Evolution: the role of spectroscopic surveys in the next decade
Over the last decade optical spectroscopic surveys have characterized the low
redshift galaxy population and uncovered populations of star-forming galaxies
back to z ~ 7. This work has shown that the primary epoch of galaxy building
and black hole growth occurs at redshifts of 2 to 3. The establishment of the
concordance LCDM cosmology shifted the focus of galaxy population studies from
constraining cosmological parameters to characterizing the processes which
regulate the formation and evolution of galaxies.In the next decade, high
redshift observers will attempt to formulate a coherent evolutionary picture
connecting galaxies in the high redshift Universe to galaxies today. In order
to link galaxy populations at different redshifts, we must not only
characterize their evolution in a systematic way, we must establish which
physical processes are responsible for it. Considerable progress has already
been made in understanding how galaxies evolved from z ~ 1 to the present day.
Large spectroscopic surveys in the near infrared are required to push these
studies back towards the main epoch of galaxy building. Only then will we
understand the full story of the formation of L* galaxies like our own Milky
Way. A large near-IR spectroscopic survey will also provide the calibration
needed to avoid systematics in the large photometric programs proposed to study
the nature of dark matter and dark energy. We provide an outline design for a
multi-object 0.4 to 1.8 micron spectrograph, which could be placed on an
existing telescope, and which would allow a full characterization of the galaxy
population out to z ~ 2. We strongly recommend a serious further study to
design a real instrument, which will be required for galaxy formation studies
to advance to the next frontier.Comment: White paper, primary author J.E. Gunn, submitted to Astro2010 Decadal
Survey, see http://www7.nationalacademies.org/bpa/Astro2010_SWP_byTitle.htm
Concert recording 2014-04-20
[Track 01]. Wie Melodien zieht es mir / J. Brahms -- [Track 02]. Sogno / F.P. Tosti -- [Track 03]. Ombra mai fu / F. Handel -- [Track 04]. O del mio dolce ardor / C.W. Gluck -- [Track 05]. Sebben crudele / A. Caldara -- [Track 06]. An den Mond / F. Schubert -- [Track 07]. Preghiera / F.P. Tosti -- [Track 08]. Vaghissima sembianza / F. Donaudy -- [Track 09]. Ich liebe dich / Beethoven -- [Track 10]. Caro mio ben / G. Giordani -- [Track 11]. Spiagge amate / C.W. Gluck -- [Track 12]. Ordinary people / John Stephens and Will Adams -- [Track 13]. For good / Stephen Schwartz -- [Track 14]. I\u27m a part of that / Jason Robert Brown -- [Track 15]. Stars / Claude-Michel Schonberg -- [Track 16]. In your atmosphere / John Mayer -- [Track 17]. Istanbul (Not Constantinople) / They Might Be Giant
A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey II: Discovery of Three Additional Quasars at z>6
We present the discovery of three new quasars at z>6 in 1300 deg^2 of SDSS
imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23) and
J163033.90+401209.6 (z=6.05). The first two objects have weak Ly alpha emission
lines; their redshifts are determined from the positions of the Lyman break.
They are only accurate to 0.05 and could be affected by the presence of broad
absorption line systems. The last object has a Ly alpha strength more typical
of lower redshift quasars. Based on a sample of six quasars at z>5.7 that cover
2870 deg^2 presented in this paper and in Paper I, we estimate the comoving
density of luminous quasars at z 6 and M_{1450} < -26.8 to be (8 +/-
3)x10^{-10} Mpc^{-3} (for H_0 = 50 km/s/Mpc, Omega = 1). HST imaging of two
z>5.7 quasars and high-resolution ground-based images (seeing 0.4'') of three
additional z>5.7 quasars show that none of them is gravitationally lensed. The
luminosity distribution of the high-redshfit quasar sample suggests the bright
end slope of the quasar luminosity function at z 6 is shallower than Psi
L^{-3.5} (2-sigma), consistent with the absence of strongly lensed objects.Comment: AJ in press (Apr 2003), 26 pages, 9 figure
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