2,318 research outputs found
The Relationship Between Religion and Attention Deficit Hyperactivity Disorder
Research shows that religious people have higher levels of self-control. Scientists also hypothesize that individuals with Attention Deficit Hyperactivity Disorder (ADHD) are less likely to participate in religious services which require long periods of attention and self discipline. However, little research has investigated the potential relationship between ADHD and religious participation. Using the National Longitudinal Study of Adolescent Health (Add Health), this study finds (1) mothers’ prayer frequency is marginally related to children’s ADHD symptoms and diagnosis although other religious indicators are not significantly related, (2) childhood religious involvement and affiliation are not significantly related to ADHD symptoms and diagnosis, and (3) childhood ADHD is not significantly related to adult religious involvement and affiliation
Spatial Contours of Potential Biomass Crop Production: An Examination of Variations by U.S. Region
The recent and projected status of energy production and consumption in the United States, resulting in substantial dependencies upon foreign oil, has continued to provide pressure on domestic energy security. All told, bio-energy systems, and biomass crop production in particular, will be important elements of national security, economic vitality, and public policy. Using biomass crop estimates based upon models developed at the Oak Ridge National Laboratory and the Department of Energy (DOE) National Renewable Energy Laboratory, we identify potential biomass crop production zones using spatial analysis methods. The Midwest and the South are, by far, the largest regions of potential production. Once potential biomass crop yield is made proportional to estimated land and production costs, the South’s optimal crop zones fall along the Gulf Coast and Atlantic Seaboard, whereas in the Midwest, they are largely in non-metropolitan localities. The implications of these spatial contours for energy policy for alternative biomass crop production are discussed
Correcting the z~8 Galaxy Luminosity Function for Gravitational Lensing Magnification Bias
We present a Bayesian framework to account for the magnification bias from
both strong and weak gravitational lensing in estimates of high-redshift galaxy
luminosity functions. We illustrate our method by estimating the UV
luminosity function using a sample of 97 Y-band dropouts (Lyman break galaxies)
found in the Brightest of Reionizing Galaxies (BoRG) survey and from the
literature. We find the luminosity function is well described by a Schechter
function with characteristic magnitude of ,
faint-end slope of , and number density of
. These
parameters are consistent within the uncertainties with those inferred from the
same sample without accounting for the magnification bias, demonstrating that
the effect is small for current surveys at , and cannot account for the
apparent overdensity of bright galaxies compared to a Schechter function found
recently by Bowler et al. (2014a,b) and Finkelstein et al. (2014). We estimate
that the probability of finding a strongly lensed source in our sample
is in the range depending on limiting magnitude. We identify one
strongly-lensed candidate and three cases of intermediate lensing in BoRG
(estimated magnification ) in addition to the previously known
candidate group-scale strong lens. Using a range of theoretical luminosity
functions we conclude that magnification bias will dominate wide field surveys
-- such as those planned for the Euclid and WFIRST missions -- especially at
. Magnification bias will need to be accounted for in order to derive
accurate estimates of high-redshift luminosity functions in these surveys and
to distinguish between galaxy formation models.Comment: Accepted for publication in ApJ. 20 pages, 13 figure
Birds as surrogates for mammals and reptiles: Are patterns of cross-taxonomic associations stable over time in a human-modified landscape?
Cross-taxonomic surrogates can be feasible alternatives to direct measurements of biodiversity in conservation if validated with robust data and used with explicit goals. However, few studies of cross-taxonomic surrogates have examined how temporal changes in composition or richness in one taxon can drive variation in concordant patterns of diversity in another taxon, particularly in a dynamic and heavily modified landscape. We examined this problem by assessing changes in cross-taxonomic associations over time between the surrogate (birds) and target vertebrate taxa (mammals, reptiles) that demand high sampling effort, in a heterogeneous mosaic landscape comprising pine monoculture, eucalypt woodland remnants and agricultural land. Focussing on four study years (1999, 2001, 2011, 2013) from a dataset spanning 15 years, we: (1) investigated temporal changes in cross-taxonomic congruency among three animal taxa, (2) explored how temporal variation in composition and species richness of each taxon might account for variation in cross-taxonomic congruency, and (3) identified habitat structural variables that are strongly correlated with species composition of each taxon. We found the strength of cross-taxonomic congruency varied between taxa in response to both landscape context and over time. Among the three taxa, overall correlations were weak but were consistently positive and strongest between birds and mammals, while correlations involving reptiles were usually weak and negative. We also found that stronger species richness and composition correlations between birds and mammals were not only more prevalent in woodland remnants in the agricultural matrix, but they also increased in strength over time. Temporal shifts in species composition differed in rate and extent among the taxa even though these changes were significant over time, while important habitat structural correlates were seldom shared across taxa. Our study highlights the role of the landscape matrix and time in shaping animal communities and the resulting cross-taxonomic associations in the woodland remnants, especially after a major perturbation event (i.e. plantation establishment). In such dynamic landscapes, differing and taxon-specific shifts in diversity over time can influence the strength, direction and consistency of cross-taxonomic correlations, therefore posing a �temporal� problem for the use of surrogates like birds in monitoring and assessments of biodiversity, and conservation management practices.Lesslie Foundation; Australian Research Council Laureate Fellowship
Cross-sectional and temporal relationships between bird occupancy and vegetation cover at multiple spatial scales
Scale is a key concept in ecology, but the statistically based quantification of scale effects has often proved difficult. This is exemplified by the challenges of quantifying relationships between biodiversity and vegetation cover at different spatial scales to guide restoration and conservation efforts in agricultural environments. We used data from 2002 to 2010 on 184 sites (viz., site scale) nested within 46 farms (the farm scale), nested within 23 landscapes (the landscape scale). We found cross-sectional relationships with the amount of vegetation cover that were typically positive for woodland birds and negative for open-country birds. However, for some species, relationships differed between spatial scales, suggesting differences in nesting and foraging requirements. There was a 3.5% increase in the amount of native vegetation cover in our study region between 2002 and 2010, and our analyses revealed that some open country species responded negatively to these temporal changes, typically at the farm and/or site scale, but not the landscape scale. Species generally exhibited stronger cross-sectional relationships with the amount of vegetation cover than relationships between changes in occupancy and temporal changes in vegetation cover. This unexpected result can be attributed to differences in habitat use by birds of existing vegetation cover (typically oldgrowth woodland) vs. plantings and natural regeneration, which are the main contributors to temporal increases in vegetation cover. By taking a multi-scaled empirical approach, we have identified species-specific, scale-dependent responses to vegetation cover. These findings are of considerable practical importance for understanding which species will respond to different scales of protection of existing areas of native vegetation, efforts to increase the amount of native vegetation over time, and both approaches together
Not All Kinds of Revegetation Are Created Equal: Revegetation Type Influences Bird Assemblages in Threatened Australian Woodland Ecosystems
The value for biodiversity of large intact areas of native vegetation is well established. The biodiversity value of regrowth vegetation is also increasingly recognised worldwide. However, there can be different kinds of revegetation that have different origins. Are there differences in the richness and composition of biotic communities in different kinds of revegetation? The answer remains unknown or poorly known in many ecosystems. We examined the conservation value of different kinds of revegetation through a comparative study of birds in 193 sites surveyed over ten years in four growth types located in semi-cleared agricultural areas of south-eastern Australia. These growth types were resprout regrowth, seedling regrowth, plantings, and old growth
Cross-taxonomic surrogates for biodiversity conservation in human-modified landscapes – A multi-taxa approach
Cross-taxonomic surrogates are often used in conservation planning because inventorying large suites of taxa is either not feasible or too costly. However, cross-taxonomic surrogates are seldom tested rigorously using both correlational and representation-based approaches at the spatial scales at which conservation management occurs. Here, we evaluated the effectiveness of five ecologically contrasting taxa (birds, herpetofauna, wild bees, beetles, trees) as cross-taxonomic surrogates in native woodland patches within a heavily modified, farming and plantation-dominated landscape. We first compared species richness and compositional heterogeneity across taxa before testing for cross-taxonomic congruence using a correlative approach. We then quantified how well each taxon incidentally represented other taxa in their best patch sets, and the costs of doing so using a complementarity-based approach. We found significant pairwise associations between some taxa (birds, bees), but no single taxon was strongly correlated with all other taxa. Woodland patch sets prioritised for beetles represented other taxa best, followed by birds, but were the costliest and required the largest amount of woodland. This contrasted with patch sets prioritised for wild bees or herpetofauna, which achieved higher representation of other taxa at lower costs. Our study highlighted the influence of taxon-specific patterns of diversity and heterogeneity on how remnant vegetation patches should be prioritised for conservation, a consideration not immediately obvious in correlative analyses of surrogacy. Second, taxa that are not the most speciose (e.g. wild bees) can be efficient surrogates for other taxa, achieving higher incidental representation at lower costs. Thus, while species-rich taxa are ideal as surrogates for prioritising conservation, conservation planners should not overlook the potential of less speciose taxa such as bees, while considering the cost-effectiveness of surveying multiple different taxa.DLY is supported by the Lesslie Foundation and an Australian National University Postgraduate Scholarship. DBL is supported by an Australian Research Council Laureate Fellowship
Binary Star Orbits from Speckle Interferometry. VI. The Nearby Solar-Type Speckle-Spectroscopic Binary HR 6697
Interferometric, spectroscopic, astrometric, and photometric observations are presented for the nearby solar-type binary HR 6697. The system consists of a G0-2 V primary and a K2-S V secondary. From a combined solution of the speckle and spectroscopic data the orbital period is 881 days or 2.41 yr, the semimajor axis is 2.1 A.U., the eccentricity is 0.42, and the inclination is 68°. The masses and luminosities are 1.16±0.12 Msun, 0.77±0.05 Msun, 1.61±0.15 Lsun, and 0.17±0.05 Lsun. Two independent determinations of the parallax, a trigonometric parallax of 0 .0379±0 .0030, and an orbital parallax of 0 .0375±0 .0014, are in excellent agreement and give a mean distance of 26.6±0.9 pc. The system appears to be metal rich relative to the Sun, and space motions do not identify it with any moving group
A Phase Glass is a Bose Metal: New Conducting State in 2D
In the quantum rotor model with random exchange interactions having a
non-zero mean, three phases, a 1) phase (Bose) glass, 2) superfluid, and 3)
Mott insulator, meet at a bi-critical point. We demonstrate that proximity to
the bi-critical point and the coupling between the energy landscape and the
dissipative degrees of freedom of the phase glass lead to a metallic state at
T=0. Consequently, the phase glass is unique in that it represents a concrete
example of a metallic state that is mediated by disorder, even in 2D. We
propose that the experimentally observed metallic phase which intervenes
between the insulator and the superconductor in a wide range of thin films is
in actuality a phase glass.Comment: 4 pages, 1 .eps figure, final version to appear in Phys. Rev. Let
Theory of sound attenuation in glasses: The role of thermal vibrations
Sound attenuation and internal friction coefficients are calculated for a
realistic model of amorphous silicon. It is found that, contrary to previous
views, thermal vibrations can induce sound attenuation at ultrasonic and
hypersonic frequencies that is of the same order or even larger than in
crystals. The reason is the internal-strain induced anomalously large
Gr\"uneisen parameters of the low-frequency resonant modes.Comment: 8 pages, 3 figures; to appear in PR
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