1,005 research outputs found
Century-scale environmental reconstruction by using stable carbon isotopes: just one method from the big bag of tricks
The field of 'historical ecology' is coming to maturity at a time when we, in Australia, are reflecting on our relationship with, and place in, the land. After an essentially ahistorical approach to land use we are now attempting to place land management into the context of environmental change since and immediately preceding Western European settlement. This volume reflects an emerging concern that, collectively, non-indigenous Australians have no 'environmental history'. One component of 'living in' rather than 'battling against' the land is developing a sense of our history. Without an oral narrative that is commonly shared, attempts to develop the story of environmental change have to be based on retrospective and reconstructive research. This volume captures part of this movement to develop an environmental narrative and context for our future relationship with the land. There are many methodological approaches to reconstructing a story of the past, from local knowledge and oral history to the 'high-tech' and hard sciences. This paper reviews methods that apply stable carbon isotope techniques to reconstruct environmental change. Although well suited to environmental history, carbon isotope techniques remain under-utilised in the Australian context. Here I review applications to highlight the strengths and limitations of carbon isotope techniques in the reconstruction of century-scale vegetation change. There have been two dominant applications of carbon isotope techniques to environmental reconstruction. These applications fall broadly into either stable carbon isotope analysis of organic matter in soils and sediments, or inferences of environmental states have been drawn from carbon isotope analysis of animal tissues and residues. The main strength of stable carbon isotope techniques is that they can be spatially precise while integrating a range of environmental information into one isotopic signal. This integrative strength is at the same time one of the major limitations of carbon isotope techniques because floristic (taxonomic) resolution is low
Radial distribution of stars, gas and dust in SINGS galaxies. I. Surface photometry and morphology
We present ultraviolet through far-infrared surface brightness profiles for
the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The
imagery used to measure the profiles includes GALEX UV data, optical images
from KPNO, CTIO and SDSS, near-IR data from 2MASS, and mid- and far-infrared
images from Spitzer. Along with the radial profiles, we also provide
multi-wavelength asymptotic magnitudes and several non-parametric indicators of
galaxy morphology: the concentration index (C_42), the asymmetry (A), the Gini
coefficient (G) and the normalized second-order moment of the brightest 20% of
the galaxy's flux (M_20). Our radial profiles show a wide range of morphologies
and multiple components (bulges, exponential disks, inner and outer disk
truncations, etc.) that vary not only from galaxy to galaxy but also with
wavelength for a given object. In the optical and near-IR, the SINGS galaxies
occupy the same regions in the C_42-A-G-M_20 parameter space as other normal
galaxies in previous studies. However, they appear much less centrally
concentrated, more asymmetric and with larger values of G when viewed in the UV
(due to star-forming clumps scattered across the disk) and in the mid-IR (due
to the emission of Polycyclic Aromatic Hydrocarbons at 8.0 microns and very hot
dust at 24 microns).Comment: 66 pages in preprint format, 14 figures, published in ApJ. The
definitive publisher authenticated version is available online at
http://dx.doi.org/10.1088/0004-637X/703/2/156
Artificial Immune Systems can find arbitrarily good approximations for the NP-Hard partition problem
Typical Artificial Immune System (AIS) operators such as hypermutations with mutation potential and ageing allow to efficiently overcome local optima from which Evolutionary Algorithms (EAs) struggle to escape. Such behaviour has been shown for artificial example functions such as Jump, Cliff or Trap constructed especially to show difficulties that EAs may encounter during the optimisation process. However, no evidence is available indicating that similar effects may also occur in more realistic problems. In this paper we perform an analysis for the standard NP-Hard Partition problem from combinatorial optimisation and rigorously show that hypermutations and ageing allow AISs to efficiently escape from local optima where standard EAs require exponential time. As a result we prove that while EAs and Random Local Search may get trapped on 4/3 approximations, AISs find arbitrarily good approximate solutions of ratio ( 1+ϵ ) for any constant ϵ within a time that is polynomial in the problem size and exponential only in 1/ϵ
In Search of the Optimal Surgical Treatment for Velopharyngeal Dysfunction in 22q11.2 Deletion Syndrome: A Systematic Review
<div><h3>Background</h3><p>Patients with the 22q11.2 deletion syndrome (22qDS) and velopharyngeal dysfunction (VPD) tend to have residual VPD following surgery. This systematic review seeks to determine whether a particular surgical procedure results in superior speech outcome or less morbidity.</p> <h3>Methodology/ Principal Findings</h3><p>A combined computerized and hand-search yielded 70 studies, of which 27 were deemed relevant for this review, reporting on a total of 525 patients with 22qDS and VPD undergoing surgery for VPD. All studies were levels 2c or 4 evidence. The methodological quality of these studies was assessed using criteria based on the Cochrane Collaboration's tool for assessing risk of bias. Heterogeneous groups of patients were reported on in the studies. The surgical procedure was often tailored to findings on preoperative imaging. Overall, 50% of patients attained normal resonance, 48% attained normal nasal emissions scores, and 83% had understandable speech postoperatively. However, 5% became hyponasal, 1% had obstructive sleep apnea (OSA), and 17% required further surgery. There were no significant differences in speech outcome between patients who underwent a fat injection, Furlow or intravelar veloplasty, pharyngeal flap pharyngoplasty, Honig pharyngoplasty, or sphincter pharyngoplasty or Hynes procedures. There was a trend that a lower percentage of patients attained normal resonance after a fat injection or palatoplasty than after the more obstructive pharyngoplasties (11–18% versus 44–62%, p = 0.08). Only patients who underwent pharyngeal flaps or sphincter pharyngoplasties incurred OSA, yet this was not statistically significantly more often than after other procedures (p = 0.25). More patients who underwent a palatoplasty needed further surgery than those who underwent a pharyngoplasty (50% versus 7–13%, p = 0.03).</p> <h3>Conclusions/ Significance</h3><p>In the heterogeneous group of patients with 22qDS and VPD, a grade C recommendation can be made to minimize the morbidity of further surgery by choosing to perform a pharyngoplasty directly instead of only a palatoplasty.</p> </div
Partner relationship satisfaction and maternal emotional distress in early pregnancy
<p>Abstract</p> <p>Background</p> <p>Recognition of maternal emotional distress during pregnancy and the identification of risk factors for this distress are of considerable clinical- and public health importance. The mental health of the mother is important both for herself, and for the physical and psychological health of her children and the welfare of the family. The first aim of the present study was to identify risk factors for maternal emotional distress during pregnancy with special focus on partner relationship satisfaction. The second aim was to assess interaction effects between relationship satisfaction and the main predictors.</p> <p>Methods</p> <p>Pregnant women enrolled in the Norwegian Mother and Child Cohort Study (n = 51,558) completed a questionnaire with questions about maternal emotional distress, relationship satisfaction, and other risk factors. Associations between 37 predictor variables and emotional distress were estimated by multiple linear regression analysis.</p> <p>Results</p> <p>Relationship dissatisfaction was the strongest predictor of maternal emotional distress (β = 0.25). Other predictors were dissatisfaction at work (β = 0.11), somatic disease (β = 0.11), work related stress (β = 0.10) and maternal alcohol problems in the preceding year (β = 0.09). Relationship satisfaction appeared to buffer the effects of frequent moving, somatic disease, maternal smoking, family income, irregular working hours, dissatisfaction at work, work stress, and mother's sick leave (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>Dissatisfaction with the partner relationship is a significant predictor of maternal emotional distress in pregnancy. A good partner relationship can have a protective effect against some stressors.</p
Air pollution and the microvasculature: A cross-sectional assessment of in vivo retinal images in the population-based multi-ethnic study of atherosclerosis (MESA)
10.1371/journal.pmed.1000372PLoS Medicine711
Mismatches in Scale Between Highly Mobile Marine Megafauna and Marine Protected Areas
Marine protected areas (MPAs), particularly large MPAs, are increasing in number and size around the globe in part to facilitate the conservation of marine megafauna under the assumption that large-scale MPAs better align with vagile life histories; however, this alignment is not well established. Using a global tracking dataset from 36 species across five taxa, chosen to reflect the span of home range size in highly mobile marine megafauna, we show most MPAs are too small to encompass complete home ranges of most species. Based on size alone, 40% of existing MPAs could encompass the home ranges of the smallest ranged species, while only \u3c 1% of existing MPAs could encompass those of the largest ranged species. Further, where home ranges and MPAs overlapped in real geographic space, MPAs encompassed \u3c 5% of core areas used by all species. Despite most home ranges of mobile marine megafauna being much larger than existing MPAs, we demonstrate how benefits from MPAs are still likely to accrue by targeting seasonal aggregations and critical life history stages and through other management techniques
Mismatches in Scale Between Highly Mobile Marine Megafauna and Marine Protected Areas
Marine protected areas (MPAs), particularly large MPAs, are increasing in number and size around the globe in part to facilitate the conservation of marine megafauna under the assumption that large-scale MPAs better align with vagile life histories; however, this alignment is not well established. Using a global tracking dataset from 36 species across five taxa, chosen to reflect the span of home range size in highly mobile marine megafauna, we show most MPAs are too small to encompass complete home ranges of most species. Based on size alone, 40% of existing MPAs could encompass the home ranges of the smallest ranged species, while only \u3c 1% of existing MPAs could encompass those of the largest ranged species. Further, where home ranges and MPAs overlapped in real geographic space, MPAs encompassed \u3c 5% of core areas used by all species. Despite most home ranges of mobile marine megafauna being much larger than existing MPAs, we demonstrate how benefits from MPAs are still likely to accrue by targeting seasonal aggregations and critical life history stages and through other management techniques
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