76 research outputs found
Non-personal services to provide metering effort at NAB, Little Creek, VA
Issued as Progress reports no. 1-4, and Final report, Project no. A-289
Grizzly bear monitoring by the Heiltsuk people as a crucible for First Nation conservation practice
Guided by deeply held cultural values, First Nations in Canada are rapidly regaining legal authority to manage natural resources. We present a research collaboration among academics, tribal government, provincial and federal government, resource managers, conservation practitioners, and community leaders supporting First Nation resource authority and stewardship. First, we present results from a molecular genetics study of grizzly bears inhabiting an important conservation area within the territory of the Heiltsuk First Nation in coastal British Columbia. Noninvasive hair sampling occurred between 2006 and 2009 in the Koeye watershed, a stronghold for grizzly bears, salmon, and Heiltsuk people. Molecular demographic analyses revealed a regionally significant population of bears, which congregate at the Koeye each salmon-spawning season. There was a minimum of 57 individual bears detected during the study period. Results also pointed to a larger than expected source geography for salmon-feeding bears in the study area (\u3e 1000 km²), as well as early evidence of a declining trend in the bear population potentially explained by declining salmon numbers. Second, we demonstrate and discuss the power of integrating scientific research with a culturally appropriate research agenda developed by indigenous people. Guided explicitly by principles from Gvi’ilas or customary law, this research methodology is coupled with Heiltsuk culture, enabling results of applied conservation science to involve and resonate with tribal leadership in ways that have eluded previous scientific endeavors. In this context, we discuss the effectiveness of research partnerships that, from the outset, create both scientific programs and integrated communities of action that can implement change. We argue that indigenous resource management requires collaborative approaches like ours, in which science-based management is embedded within a socially and culturally appropriate context. We emerge not only with a set of guiding principles for resource management by the Heiltsuk, but a broadly applicable strategy that fosters intimacy with traditional lands and resources and provides a powerful engine for conservation
Spectropolarimetric Evidence for Radiatively Inefficient Accretion in an Optically Dull Active Galaxy
We present Subaru/FOCAS spectropolarimetry of two active galaxies in the
Cosmic Evolution Survey. These objects were selected to be optically dull, with
the bright X-ray emission of an AGN but missing optical emission lines in our
previous spectroscopy. Our new observations show that one target has very weak
emission lines consistent with an optically dull AGN, while the other object
has strong emission lines typical of a host-diluted Type 2 Seyfert galaxy. In
neither source do we observe polarized emission lines, with 3-sigma upper
limits of P_BLR < 2%. This means that the missing broad emission lines (and
weaker narrow emission lines) are not due to simple anisotropic obscuration,
e.g., by the canonical AGN torus. The weak-lined optically dull AGN exhibits a
blue polarized continuum with P = 0.78 +/- 0.07% at 4400 A < lambda_rest < 7200
A (P = 1.37 +/- 0.16% at 4400 A < lambda_rest < 5050 A). The wavelength
dependence of this polarized flux is similar to that of an unobscured AGN
continuum and represents the intrinsic AGN emission, either as synchrotron
emission or the outer part of an accretion disk reflected by a clumpy dust
scatterer. Because this intrinsic AGN emission lacks emission lines, this
source is likely to have a radiatively inefficient accretion flow.Comment: Accepted to ApJ. 6 pages, 2 figure
Molecular Gas in the z=1.2 Ultraluminous Merger GOODS J123634.53+621241.3
We report the detection of CO(2-1) emission from the z=1.2 ultraluminous
infrared galaxy (ULIRG) GOODS J123634.53+621241.3 (also known as the
sub-millimeter galaxy GN26). These observations represent the first discovery
of high-redshift CO emission using the new Combined Array for Research in
Millimeter-Wave Astronomy (CARMA). Of all high-redshift (z>1) galaxies within
the GOODS-North field, this source has the largest far-infrared (FIR) flux
observed in the Spitzer 70um and 160um bands. The CO redshift confirms the
optical identification of the source, and the bright CO(2-1) line suggests the
presence of a large molecular gas reservoir of about 7x10^10 M(sun). The
infrared-to-CO luminosity ratio of L(IR)/L'(CO) = 80+/-30 L(sun) (K Km/s
pc^2)^-1 is slightly smaller than the average ratio found in local ULIRGs and
high-redshift sub-millimeter galaxies. The short star-formation time scale of
about 70 Myr is consistent with a starburst associated with the merger event
and is much shorter than the time scales for spiral galaxies and estimates made
for high-redshift galaxies selected on the basis of their B-z and z-K colors.Comment: Accepted for publication in ApJ Letter
Luminous Red Galaxy Clustering at z~0.7 - First Results using AAOmega
We report on the AAT-AAOmega LRG Pilot observing run to establish the
feasibility of a large spectroscopic survey using the new AAOmega instrument.
We have selected Luminous Red Galaxies (LRGs) using single epoch SDSS
riz-photometry to i<20.5 and z<20.2. We have observed in 3 fields including the
COSMOS field and the COMBO-17 S11 field, obtaining a sample of ~600 redshift
z>=0.5 LRGs. Exposure times varied from 1 - 4 hours to determine the minimum
exposure for AAOmega to make an essentially complete LRG redshift survey in
average conditions. We show that LRG redshifts to i<20.5 can measured in
approximately 1.5hr exposures and present comparisons with 2SLAQ and COMBO-17
(photo-)redshifts. Crucially, the riz selection coupled with the 3-4 times
improved AAOmega throughput is shown to extend the LRG mean redshift from
z=0.55 for 2SLAQ to z=0.681+/- 0.005 for riz-selected LRGs. This extended range
is vital for maximising the S/N for the detection of the baryon acoustic
oscillations (BAOs). Furthermore, we show that the amplitude of LRG clustering
is s_0 = 9.9+/-0.7 h^-1 Mpc, as high as that seen in the 2SLAQ LRG Survey.
Consistent results for the real-space amplitude are found from projected and
semi-projected correlation functions. This high clustering amplitude is
consistent with a long-lived population whose bias evolves as predicted by a
simple ``high-peaks'' model. We conclude that a redshift survey of 360 000 LRGs
over 3000deg^2, with an effective volume some 4 times bigger than previously
used to detect BAO with LRGs, is possible with AAOmega in 170 nights.Comment: 12 pages, 7 figures, 8 tables, minor changes, matches published
versio
The Evolution of the Star Formation Rate of Galaxies at 0.0 < z < 1.2
We present the 24 micron rest-frame luminosity function (LF) of star-forming
galaxies in the redshift range 0.0 < z < 0.6 constructed from 4047
spectroscopic redshifts from the AGN and Galaxy Evolution Survey of 24 micron
selected sources in the Bootes field of the NOAO Deep Wide-Field Survey. This
sample provides the best available combination of large area (9 deg^2), depth,
and statistically complete spectroscopic observations, allowing us to probe the
evolution of the 24 micron LF of galaxies at low and intermediate redshifts
while minimizing the effects of cosmic variance. In order to use the observed
24 micron luminosity as a tracer for star formation, active galactic nuclei
(AGNs) that could contribute significantly at 24 micron are identified and
excluded from our star-forming galaxy sample based on their mid-IR spectral
energy distributions or the detection of X-ray emission. The evolution of the
24 micron LF of star-forming galaxies for redshifts of z < 0.65 is consistent
with a pure luminosity evolution where the characteristic 24 micron luminosity
evolves as (1+z)^(3.8+/-0.3). We extend our evolutionary study to encompass 0.0
< z < 1.2 by combining our data with that of the Far-Infrared Deep
Extragalactic Legacy Survey. Over this entire redshift range the evolution of
the characteristic 24 micron luminosity is described by a slightly shallower
power law of (1+z)^(3.4+/-0.2). We find a local star formation rate density of
(1.09+/-0.21) x 10^-2 Msun/yr/Mpc^-3, and that it evolves as (1+z)^(3.5+/-0.2)
over 0.0 < z < 1.2. These estimates are in good agreement with the rates using
optical and UV fluxes corrected for the effects of intrinsic extinction in the
observed sources. This agreement confirms that star formation at z <~ 1.2 is
robustly traced by 24 micron observations and that it largely occurs in
obscured regions of galaxies. (Abridged)Comment: ApJ, in press, 16 pages 9 figure
The Chandra COSMOS Survey, I: Overview and Point Source Catalog
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program
that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h,
+02deg) with an effective exposure of ~160ksec, and an outer 0.4sq.deg. area
with an effective exposure of ~80ksec. The limiting source detection depths are
1.9e-16 erg cm(-2) s(-1) in the Soft (0.5-2 keV) band, 7.3e(-16) erg cm^-2 s^-1
in the Hard (2-10 keV) band, and 5.7e(-16) erg cm(-2) s(-1) in the Full (0.5-10
keV) band. Here we describe the strategy, design and execution of the C-COSMOS
survey, and present the catalog of 1761 point sources detected at a probability
of being spurious of <2e(-5) (1655 in the Full, 1340 in the Soft, and 1017 in
the Hard bands). By using a grid of 36 heavily (~50%) overlapping pointing
positions with the ACIS-I imager, a remarkably uniform (to 12%) exposure across
the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower
flux limit. The widely different PSFs obtained in each exposure at each point
in the field required a novel source detection method, because of the
overlapping tiling strategy, which is described in a companion paper. (Puccetti
et al. Paper II). This method produced reliable sources down to a 7-12 counts,
as verified by the resulting logN-logS curve, with sub-arcsecond positions,
enabling optical and infrared identifications of virtually all sources, as
reported in a second companion paper (Civano et al. Paper III). The full
catalog is described here in detail, and is available on-line.Comment: Revised to omit egregious bold facing and fix missing ',' in author
lis
Isolation and Characterization of Intestinal Stem Cells Based on Surface Marker Combinations and Colony-Formation Assay
Identification of intestinal stem cells (ISCs) has relied heavily on the use of transgenic reporters in mice, but this approach is limited by mosaic expression patterns and difficult to directly apply to human tissues. We sought to identify reliable surface markers of ISCs and establish a robust functional assay to characterize ISCs from mouse and human tissues
- …