2,683 research outputs found
The Local Food System Vitality Index: A Pilot Analysis to Demonstrate a Process for Measuring System Performance and Development
Identifying successful development priorities for local food systems (LFSs) is a challenge for producers, LFS advocates, Extension agents, and policymakers. Consumer perceptions and preferences regarding what constitutes an active, healthy, and vibrant LFS often differ within and between diverse communities. Producers, development entities, and others would benefit from rapid assessment processes that provide detailed information on consumer preferences and potential market opportunities within their LFS.
In this paper, we introduce the analytic possibilities of our Local Food System Vitality Index (LFSVI). Using data collected from a pilot survey in Lexington, Kentucky, we rapidly assess the performance of 20 different components of our LFS. The LFSVI differs from most other food system and quality-of-life indices by focusing on the perceptions of resident food consumers.
In our analysis, we identify that Lexington residents generally associate farmers markets, farm-to-fork restaurants, local product diversity, and retail sourcing of local food with high overall vitality of the local food system. While residents score the first three components as high performing, they perceive the retail component to be less functional. We use results such as these to compare which aspects of the LFS are valued versus which are high performing. We do this comparison across different resident food consumer segments in and between geographic locations. Throughout our analysis, we discuss how this index method is generally applicable and conducive to identifying LFS development priorities
Evidence of boosted 13CO/12CO ratio in early-type galaxies in dense environments
We present observations of CO(1-0) in 17 Combined Array for Research
in Millimeter Astronomy (CARMA) Atlas3D early-type galaxies (ETGs), obtained
simultaneously with CO(1-0) observations. The CO in six ETGs is
sufficiently bright to create images. In these 6 sources, we do not detect any
significant radial gradient in the CO/CO ratio between the
nucleus and the outlying molecular gas. Using the CO channel maps as 3D
masks to stack the CO emission, we are able to detect 15/17 galaxies to
(and 12/17 to at least 5) significance in a spatially
integrated manner. Overall, ETGs show a wide distribution of
CO/CO ratios, but Virgo cluster and group galaxies preferentially
show a CO/CO ratio about 2 times larger than field galaxies,
although this could also be due to a mass dependence, or the CO spatial extent
(). ETGs whose gas has a morphologically-settled
appearance also show boosted CO/CO ratios. We hypothesize that
this variation could be caused by (i) the extra enrichment of gas from
molecular reprocessing occurring in low-mass stars (boosting the abundance of
C to C in the absence of external gas accretion), (ii) much
higher pressure being exerted on the midplane gas (by the intracluster medium)
in the cluster environment than in isolated galaxies, or (iii) all but the
densest molecular gas clumps being stripped as the galaxies fall into the
cluster. Further observations of CO in dense environments, particularly
of spirals, as well as studies of other isotopologues, should be able to
distinguish between these hypotheses.Comment: 13 pages, 3 tables, 7 figures, accepted by MNRA
AEGIS: Chandra Observation of DEEP2 Galaxy Groups and Clusters
We present a 200 ksec Chandra observation of seven spectroscopically
selected, high redshift (0.75 < z < 1.03) galaxy groups and clusters discovered
by the DEEP2 Galaxy Redshift Survey in the Extended Groth Strip (EGS). X-ray
emission at the locations of these systems is consistent with background. The
3-sigma upper limits on the bolometric X-ray luminosities (L_X) of these
systems put a strong constraint on the relation between L_X and the velocity
dispersion of member galaxies sigma_gal at z~1; the DEEP2 systems have lower
luminosity than would be predicted by the local relation. Our result is
consistent with recent findings that at high redshift, optically selected
clusters tend to be X-ray underluminous. A comparison with mock catalogs
indicates that it is unlikely that this effect is entirely caused by a
measurement bias between sigma_gal and the dark matter velocity dispersion.
Physically, the DEEP2 systems may still be in the process of forming and hence
not fully virialized, or they may be deficient in hot gas compared to local
systems. We find only one possibly extended source in this Chandra field, which
happens to lie outside the DEEP2 coverage.Comment: 5 pages, 3 figures. Accepted for publication in AEGIS ApJ Letters
special editio
Star Formation in Nearby Early-Type Galaxies: The Radio Continuum Perspective
We present a 1.4 GHz Karl G. Jansky Very Large Array (VLA) study of a sample
of early-type galaxies (ETGs) from the volume- and magnitude-limited ATLAS-3D
survey. The radio morphologies of these ETGs at a resolution of 5" are diverse
and include sources that are compact on sub-kpc scales, resolved structures
similar to those seen in star-forming spiral galaxies, and kpc-scale radio
jets/lobes associated with active nuclei. We compare the 1.4 GHz, molecular
gas, and infrared (IR) properties of these ETGs. The most CO-rich ATLAS-3D ETGs
have radio luminosities consistent with extrapolations from H_2-mass-derived
star formation rates from studies of late-type galaxies. These ETGs also follow
the radio-IR correlation. However, ETGs with lower molecular gas masses tend to
have less radio emission relative to their CO and IR emission compared to
spirals. The fraction of galaxies in our sample with high IR-radio ratios is
much higher than in previous studies, and cannot be explained by a systematic
underestimation of the radio luminosity due to the presence extended,
low-surface-brightness emission that was resolved-out in our VLA observations.
In addition, we find that the high IR-radio ratios tend to occur at low IR
luminosities, but are not associated with low dynamical mass or metallicity.
Thus, we have identified a population of ETGs that have a genuine shortfall of
radio emission relative to both their IR and molecular gas emission. A number
of mechanisms may conspire to cause this radio deficiency, including a
bottom-heavy stellar initial mass function, weak magnetic fields, a higher
prevalence of environmental effects compared to spirals and enhanced cosmic ray
losses.Comment: accepted for publication in MNRA
The DEEP2 Galaxy Redshift Survey: Clustering of Groups and Group Galaxies at z~1
We study the clustering properties of groups and of galaxies in groups in the
DEEP2 Galaxy Redshift Survey dataset at z~1. Four clustering measures are
presented: 1) the group correlation function for 460 groups with estimated
velocity dispersions of sigma>200 km/s, 2) the galaxy correlation for the full
galaxy sample, using a flux-limited sample of 9800 objects between 0.7<z<1.0,
3) the galaxy correlation for galaxies in groups, and 4) the group-galaxy
cross-correlation function. Using the observed number density and clustering
amplitude of the groups, the estimated minimum group dark matter halo mass is
M_min~6 10^12 h^-1 M_Sun for a flat LCDM cosmology. Groups are more clustered
than galaxies, with a relative bias of b=1.7 +/-0.04 on scales r_p=0.5-15
Mpc/h. Galaxies in groups are also more clustered than the full galaxy sample,
with a scale-dependent relative bias which falls from b~2.5 +/-0.3 at r_p=0.1
Mpc/h to b~1 +/-0.5 at r_p=10 Mpc/h. The correlation functions for all galaxies
and galaxies in groups can be fit by a power-law on scales r_p=0.05-20 Mpc/h.
We empirically measure the contribution to the projected correlation function
for galaxies in groups from a `one-halo' term and a `two-halo' term by counting
pairs of galaxies in the same or in different groups. The projected
cross-correlation between shows that red galaxies are more centrally
concentrated in groups than blue galaxies at z~1. DEEP2 galaxies in groups
appear to have a shallower radial distribution than that of mock galaxy
catalogs made from N-body simulations, which assume a central galaxy surrounded
by satellite galaxies with an NFW profile. We show that the clustering of
galaxies in groups can be used to place tighter constraints on the halo model
than can be gained from using the usual galaxy correlation function alone.Comment: 22 pages, 12 figures, in emulateapj format, accepted to ApJ, minor
changes made to match published versio
To exclose nests or not: structured decision making for the conservation of a threatened species
Decisions regarding endangered species recovery often face sparse data and multiple sources of uncertainty about the effects of management. Structured decision making (SDM) provides a framework for assembling knowledge and expert opinion and evaluating the tradeoffs between different objectives while formally incorporating uncertainty. The Atlantic Coast piping plover provides an illustrative case for the utility of SDM in endangered species management because its population growth is simple to model, most populations are monitored, decision alternatives are well defined, and many managers are open to recovery recommendations. We built a model to evaluate the decision to use nest exclosures to protect piping plover eggs from predators, where the objective was to maximize λ and the tradeoff was between nest survival and adult survival. The latter can be reduced by exclosures. We used a novel mixed multinomial logistic exposure model to predict daily nest fates and incorporated the results into a stochastic projection matrix that included renesting after nest failure, and adult mortality associated with abandonment. In our test data set (n = 329 nests from 28 sites over four years), the mean nest survival over 34 days was markedly higher for exclosed nests (0.76 ± 0.03 SE) than for unexclosed nests (0.37 ± 0.07). Abandonment rates were also higher for exclosed nests (0.092 ± 0.017) than for unexclosed nests (0.045 ± 0.017), but the difference was not statistically signifi- cant and the loss rate to “other sources” (mostly predators) was much lower for exclosed nests (0.15 ± 0.03) than for unexclosed nests (0.58 ± 0.07). Population growth rate (λ) was clearly improved by exclosure use at the sites with high background nest loss rates, but λ was still \u3c1 with exclosure use. Where the background nest loss rates were low, the decision to use exclosures was ambiguous, and λ could benefit from reducing uncertainty in vital rates. Our process demonstrated that geographic and temporal variation in nest mortality determines whether exclosures will be useful in attaining positive population growth rates and that other management options must be considered where the background nest mortality rates are high
The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups
We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). The catalog contains 1165 groups with two or more members in the EGS over the redshift range 0 0.6 in the rest of DEEP2. Twenty-five percent of EGS galaxies and fourteen percent of high-z DEEP2 galaxies are assigned to galaxy groups. The groups were detected using the Voronoi-Delaunay method (VDM) after it has been optimized on mock DEEP2 catalogs following similar methods to those employed in Gerke et al. In the optimization effort, we have taken particular care to ensure that the mock catalogs resemble the data as closely as possible, and we have fine-tuned our methods separately on mocks constructed for the EGS and the rest of DEEP2. We have also probed the effect of the assumed cosmology on our inferred group-finding efficiency by performing our optimization on three different mock catalogs with different background cosmologies, finding large differences in the group-finding success we can achieve for these different mocks. Using the mock catalog whose background cosmology is most consistent with current data, we estimate that the DEEP2 group catalog is 72% complete and 61% pure (74% and 67% for the EGS) and that the group finder correctly classifies 70% of galaxies that truly belong to groups, with an additional 46% of interloper galaxies contaminating the catalog (66% and 43% for the EGS). We also confirm that the VDM catalog reconstructs the abundance of galaxy groups with velocity dispersions above ~300 km s^(–1) to an accuracy better than the sample variance, and this successful reconstruction is not strongly dependent on cosmology. This makes the DEEP2 group catalog a promising probe of the growth of cosmic structure that can potentially be used for cosmological tests
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