305 research outputs found
Starburst or AGN Dominance in Submillimetre-Luminous Candidate AGN?
It is widely believed that ultraluminous infrared (IR) galaxies and active
galactic nuclei (AGN) activity are triggered by galaxy interactions and
merging, with the peak of activity occurring at z~2, where submillimetre
galaxies are thousands of times more numerous than local ULIRGs. In this
evolutionary picture, submillimetre galaxies (SMGs) would host an AGN, which
would eventually grow a black hole (BH) strong enough to blow off all of the
gas and dust leaving an optically luminous QSO. To probe this evolutionary
sequence we have focussed on the 'missing link' sources, which demonstrate both
strong starburst (SB) and AGN signatures, in order to determine if the SB is
the main power source even in SMGs when we have evidence that an AGN is present
from their IRAC colours. The best way to determine if a dominant AGN is present
is to look for their signatures in the mid-infrared with the Spitzer IRS, since
often even deep X-ray observations miss identifying the presence of AGN in
heavily dust-obscured SMGs. We present the results of our audit of the energy
balance between star-formation and AGN within this special sub-population of
SMGs -- where the BH has grown appreciably to begin heating the dust emission.Comment: 2 pages, 1 figure. To appear in "Hunting for the Dark: The Hidden
Side of Galaxy Formation", Malta, 19-23 Oct. 2009, eds. V.P. Debattista and
C.C. Popescu, AIP Conf. Ser., in pres
The HiZELS/UKIRT large area survey for bright Lyman-alpha emitters at z~9
We present the largest area survey to date (1.4 deg2) for Lyman-alpha
emitters (LAEs) at z~9, as part of the Hi-z Emission Line Survey (HiZELS). The
survey, which primarily targets H-alpha emitters at z < 3, uses the Wide Field
CAMera on the United Kingdom Infrared Telescope and a custom narrow-band filter
in the J band to reach a Lyman-alpha luminosity limit of ~10^43.8 erg/s over a
co-moving volume of 1.12x10^6 Mpc^3 at z = 8.96+-0.06. Two candidates were
found out of 1517 line emitters, but those were rejected as LAEs after
follow-up observations. This improves the limit on the space density of bright
Lyman-alpha emitters by 3 orders of magnitude and is consistent with
suppression of the bright end of the Lyman-alpha luminosity function beyond
z~6. Combined with upper limits from smaller but deeper surveys, this rules out
some of the most extreme models for high-redshift Lyman-alpha emitters. The
potential contamination of narrow-band Lyman-alpha surveys at z>7 by Galactic
brown dwarf stars is also examined, leading to the conclusion that such
contamination may well be significant for searches at 7.7 < z < 8.0, 9.1 < z <
9.5 and 11.7 < z < 12.2.Comment: To appear in proceedings of "UKIRT at 30: A British Success Story
The mere exposure effect depends on an odorâs initial pleasantness
The mere exposure phenomenon refers to improvement of one's attitude toward an a priori neutral stimulus after its repeated exposure. The extent to which such a phenomenon influences evaluation of a priori emotional stimuli remains under-investigated. Here we investigated this question by presenting participants with different odors varying in a priori pleasantness during different sessions spaced over time. Participants were requested to report each odor's pleasantness, intensity, and familiarity. As expected, participants became more familiar with all stimuli after the repetition procedure. However, while neutral and mildly pleasant odors showed an increase in pleasantness ratings, unpleasant and very pleasant odors remained unaffected. Correlational analyses revealed an inverse U-shape between the magnitude of the mere exposure effect and the initial pleasantness of the odor. Consequently, the initial pleasantness of the stimuli appears to modulate the impact of repeated exposures on an individual's attitude. These data underline the limits of mere exposure effect and are discussed in light of the biological relevance of odors for individual survival
Progress toward sonifying Napoleonâs march and fluid flow simulations through binaural horizons
Cross-modal data analyticsâthat can be rendered for experience
through vision, hearing, and touchâposes a fundamental
challenge to designers. Non-linguistic sonification is a
well-researched means for non-visual pattern recognition but
higher density datasets pose a challenge. Because human hearing
is optimized for detecting locations on a horizontal plane, our
approach recruits this optimization by employing an immersive
binaural horizontal plane using auditory icons. Two case studies
demonstrate our approach: A sonic translation of a map and a
sonic translation of a computational fluid dynamics simulation
Origins of the extragalactic background at 1mm from a combined analysis of the AzTEC and MAMBO data in GOODS-N
We present a study of the cosmic infrared background, which is a measure of
the dust obscured activity in all galaxies in the Universe. We venture to
isolate the galaxies responsible for the background at 1mm; with spectroscopic
and photometric redshifts we constrain the redshift distribution of these
galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC
1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure
detections, 13 of which are new. By averaging the 1.16mm flux densities of
individually undetected galaxies with 24um flux densities > 25uJy, we resolve
31--45 per cent of the 1.16mm background. Repeating our analysis on the SCUBA
850um map, we resolve a higher percentage (40--64 per cent) of the 850um
background. A majority of the background resolved (attributed to individual
galaxies) at both wavelengths comes from galaxies at z > 1.3. If the ratio of
the resolved submillimeter to millimeter background is applied to a reasonable
scenario for the origins of the unresolved submillimeter background, 60--88 per
cent of the total 1.16mm background comes from galaxies at z > 1.3.Comment: 12 pages, 10 figures. Accepted by MNRAS. The combined map is publicly
available at http://www.astro.umass.edu/~pope/goodsn_mm
Sonification of Flow Instabilities in CFD Aneurysm Models
Paper presented at 2018 Canadian Society of Mechanical Engineers International Congress, 27-30 May 2018.Recent investigations using image-based computational flow dynamics (CFD) have revealed turbulent-like blood flow instabilities (hemodynamics) within intracranial cerebral aneurysms and surrounding vasculature, which may contribute to aneurysm initiation, growth, and rupture. We describe a method derived from spectral decomposition of flow for inspecting and characterizing these âturbulent-likeâ hemodynamic structures in intracranial aneurysms by sonification of CFD generated data. Motivated by auscultation techniques, the current research seeks to address the limitations of conventional CFD animations by allowing the user to listen to complex flow patterns that are often difficult to discern visually. In the process, the proposed method of sonification is successfully applied to a series of datasets resulting from highfidelity numerical simulations of intracranial aneurysms. The resulting framework is shown to be highly efficient in performing parametric sonification in real time
Know Your Audience: Designing a Nutrition Education Game for Middle School Kids
Purpose: In recent years video games have emerged as potential tools to tackle obesity. Games that use motion-sensing controllers and interfaces are often used to promote physical activity. Games are also used to impart education about diet, nutrition and health. Our goal in this project is to address childhood obesity through the design, development and implementation of a video game to teach nutrition concepts to middle-school-aged children.
Method: Our target audience is middle-school students in a low-income neighborhood in Dallas. To guide us in the game design, we collected data about studentsâ gaming preferences through surveys, focus groups and student critiques of existing games. The survey addressed studentsâ choice of gaming platform and frequency of game play. Through focus groups we explored their gaming preferences and opinions on game features. For the critiques, students played nutrition-themed games from the âApps for Healthy Kidsâ competition and completed an open-ended survey about those games.
Results: We collected data from 76 students (ages 12 â 15 years). 72% of them play games regularly (at least once a week) on consoles while 73% play on portable devices, 68% on computers and 62% play browser-based games. Console games were preferred by 89% of boys but only 56% of girls. The numbers were 81% & 66% for portable devices, but almost the same for computer games and browser-based games. Students preferred action games, games that allowed character customization and games that had multiple levels. Several students are turned off by strong depictions of violence. Students liked the nutrition themed games, but only one game really engaged them. They wanted the food in these games to look real and wanted more familiar food choices.
Conclusions: Our observations and height and weight data indicate that malnutrition rather than obesity is likely a bigger problem for these children. Consoles and portable devices were the platforms of choice although there are differences by gender. The results also provide insights into what is likely to work for this audience in terms of game mechanics and game features. The results also reinforce the need for using multiple approaches to collecting data
Satellite inventory of Minnesota forest resources
The methods and results of using Landsat Thematic Mapper (TM) data to classify and estimate the acreage of forest covertypes in northeastern Minnesota are described. Portions of six TM scenes covering five counties with a total area of 14,679 square miles were classified into six forest and five nonforest classes. The approach involved the integration of cluster sampling, image processing, and estimation. Using cluster sampling, 343 plots, each 88 acres in size, were photo interpreted and field mapped as a source of reference data for classifier training and calibration of the TM data classifications. Classification accuracies of up to 75 percent were achieved; most misclassification was between similar or related classes. An inverse method of calibration, based on the error rates obtained from the classifications of the cluster plots, was used to adjust the classification class proportions for classification errors. The resulting area estimates for total forest land in the five-county area were within 3 percent of the estimate made independently by the USDA Forest Service. Area estimates for conifer and hardwood forest types were within 0.8 and 6.0 percent respectively, of the Forest Service estimates. A trial of a second method of estimating the same classes as the Forest Service resulted in standard errors of 0.002 to 0.015. A study of the use of multidate TM data for change detection showed that forest canopy depletion, canopy increment, and no change could be identified with greater than 90 percent accuracy. The project results have been the basis for the Minnesota Department of Natural Resources and the Forest Service to define and begin to implement an annual system of forest inventory which utilizes Landsat TM data to detect changes in forest cover
Structure and function of an insect α-carboxylesterase (α Esterase 7) associated with insecticide resistance
Insect carboxylesterases from the αEsterase gene cluster, such as αE7 (also known as E3) from the Australian sheep blowfly Lucilia cuprina (LcαE7), play an important physiological role in lipid metabolism and are implicated in the detoxification of or
A bright, spatially extended lensed galaxy at z = 1.7 behind the cluster RCS2 032727-132623
We present the discovery of an extremely bright and extended lensed source
from the second Red Sequence Cluster Survey (RCS2). RCSGA 032727-132609 is
spectroscopically confirmed as a giant arc and counter-image of a background
galaxy at , strongly-lensed by the foreground galaxy cluster RCS2
032727-132623 at . The giant arc extends over \,\arcsec and
has an integrated -band magnitude of 19.15, making it times larger
and times brighter than the prototypical lensed galaxy MS1512-cB58.
This is the brightest distant lensed galaxy in the Universe known to date. Its
location in the `redshift desert' provides unique opportunities to connect
between the large samples of galaxies known at and . We have
collected photometry in 9 bands, ranging from to , which densely
sample the rest-frame UV and optical light, including the age-sensitive
4000\AA\ break. A lens model is constructed for the system, and results in a
robust total magnification of for the counter-image; we
estimate an average magnification of for the giant arc based on
the relative physical scales of the arc and counter-image. Fits of
single-component spectral energy distribution (SED) models to the photometry
result in a moderately young age, \,Myr, small amounts of dust,
, and an exponentially declining star formation history with
\textit{e}-folding time \,Myr. After correcting for the lensing
magnification, we find a stellar mass of
. Allowing for episodic star
formation, an underlying old burst could contain up to twice the mass inferred
from single-component modeling. This stellar mass estimate is consistent with
the average stellar mass of a sample of `BM' galaxies () studied
by Reddy et al. (2006).Comment: 13 pages, 8 figures, abstract abridge
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