251 research outputs found
Giant lobelias exemplify convergent evolution
Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution
Marine macroalgae as food for earthworms: Growth and selection experiments across ecotypes
Historically, subsistence farmers around the Atlantic coast of NW Europe utilised marine algae as a fertiliser in agroecosystems, a practice that continued in small areas and is now considered to have real potential for re-establishing sustainable food production systems on marginal soils. Earthworms form a significant component of soil fauna and their ecosystem services are well documented. Therefore, palatability of marine organic amendments to faunal detritivores of terrestrial systems is of interest. This work aimed to assess the potential for growth of Aporrectodea caliginosa, Lumbricus rubellus and Aporrectodea longa fed with two common macroalgae (seaweeds), Laminaria digitata and Fucus serratus. In addition, choice chambers were constructed to permit earthworm selection of these macroalgae with more conventional organic materials, horse manure (HM) and birch leaves (BL). Over a period of two months, earthworm species showed significantly greater mass gain with conventional food (p<0.05). Laminaria outperformed Fucus, which in turn was superior to soil alone. Similarly, when given a choice, a significant preference (p<0.001) was shown for the more nitrogen-rich HM and BL over the seaweeds. No removal was recorded for A. caliginosa when offered seaweeds only. By contrast, L. rubellus and A. longa showed significant preferences (p<0.001) for Laminaria over Fucus and fresh material over degraded. These results underline an interest to profit from natural resources (seaweeds) to maintain or improve soil biological quality in marginal coastal areas
An examination of cancer epidemiology studies among populations living close to toxic waste sites
<p>Abstract</p> <p>Background</p> <p>Toxic waste sites contain a broad range of suspected or confirmed human carcinogens, and remain a source of concern to many people, particularly those living in the vicinity of a site. Despite years of study, a consensus has not emerged regarding the cancer risk associated with such sites.</p> <p>Methods</p> <p>We examined the published, peer-reviewed literature addressing cancer incidence or mortality in the vicinity of toxic waste sites between 1980 and 2006, and catalogued the methods employed by such studies.</p> <p>Results</p> <p>Nineteen studies are described with respect to eight methodological criteria. Most were ecological, with minimal utilization of hydrogeological or air pathway modeling. Many did not catalogue whether a potable water supply was contaminated, and very few included contaminant measurements at waste sites or in subjects' homes. Most studies did not appear to be responses to a recognized cancer mortality cluster. Studies were highly variable with respect to handling of competing risk factors and multiple comparisons.</p> <p>Conclusion</p> <p>We conclude that studies to date have generated hypotheses, but have been of limited utility in determining whether populations living near toxic waste sites are at increased cancer risk.</p
Fermi velocity engineering in graphene by substrate modification
The Fermi velocity is one of the key concepts in the study of a material, as
it bears information on a variety of fundamental properties. Upon increasing
demand on the device applications, graphene is viewed as a prototypical system
for engineering Fermi velocity. Indeed, several efforts have succeeded in
modifying Fermi velocity by varying charge carrier concentration. Here we
present a powerful but simple new way to engineer Fermi velocity while holding
the charge carrier concentration constant. We find that when the environment
embedding graphene is modified, the Fermi velocity of graphene is (i) inversely
proportional to its dielectric constant, reaching ~2.5 m/s, the
highest value for graphene on any substrate studied so far and (ii) clearly
distinguished from an ordinary Fermi liquid. The method demonstrated here
provides a new route toward Fermi velocity engineering in a variety of
two-dimensional electron systems including topological insulators.Comment: accepted in Scientific Report
Hv-CBF2A overexpression in barley accelerates COR gene transcript accumulation and acquisition of freezing tolerance during cold acclimation
Abstract C-Repeat Binding Factors (CBFs) are DNAbinding
transcriptional activators of gene pathways imparting
freezing tolerance. Poaceae contain three CBF subfamilies,
two of which, HvCBF3/CBFIII and HvCBF4/CBFIV,
are unique to this taxon. To gain mechanistic insight into
HvCBF4/CBFIV CBFs we overexpressed Hv-CBF2A in
spring barley (Hordeum vulgare) cultivar ‘Golden Promise’.
The Hv-CBF2A overexpressing lines exhibited stunted
growth, poor yield, and greater freezing tolerance compared
to non-transformed ‘Golden Promise’. Differences in
freezing tolerance were apparent only upon cold acclimation.
During cold acclimation freezing tolerance of the
Hv-CBF2A overexpressing lines increased more rapidly
than that of ‘Golden Promise’ and paralleled the freezing
tolerance of the winter hardy barley ‘Dicktoo’. Transcript
levels of candidate CBF target genes, COR14B and DHN5
were increased in the overexpressor lines at warm temperatures,
and at cold temperatures they accumulated to much
higher levels in the Hv-CBF2A overexpressors than in
‘Golden Promise’. Hv-CBF2A overexpression also
increased transcript levels of other CBF genes at FROST
RESISTANCE-H2-H2 (FR-H2) possessing CRT/DRE sites
in their upstream regions, the most notable of which was
CBF12. CBF12 transcript levels exhibited a relatively constant
incremental increase above levels in ‘Golden Promise’
both at warm and cold. These data indicate that Hv-CBF2A
activates target genes at warm temperatures and that transcript
accumulation for some of these targets is greatly
enhanced by cold temperatures
Vessel-Associated Transforming Growth Factor-Beta1 (TGF-β1) Is Increased in the Bronchial Reticular Basement Membrane in COPD and Normal Smokers
BACKGROUND: Transforming growth factor-beta1 (TGF-β1) is a multipotential cytokine with angiogenic activity. There are only limited data about its role in airway remodeling in COPD. We have previously shown that the reticular basement membrane (Rbm) is hypervascular in the airways of current smokers either with or without chronic obstructive pulmonary disease (COPD). This study evaluated TGF-β1 immunostaining in the Rbm and its relationship to vascularity in smokers with or without COPD. METHODOLOGY/PRINCIPAL FINDINGS: Bronchial biopsies from 15 smokers with normal lung function, 19 current and 14 ex-smokers with COPD were immunostained for TGF-β1 antibody and compared to 17 healthy controls. The percentage area of tissue and also number and area of vessels staining positively for TGF-β1 were measured and compared between groups. Some bronchial biopsies from current smoking COPD subjects were also stained for phosphorylated (active) Smad2/3. Epithelial TGF- β1 staining was not different between COPD current smokers and normal controls. TGF-β1 stained vessels in the Rbm were increased in smokers with normal lung function, current smoking COPD and ex-smokers with COPD compared to controls [median (range) for number of vessels/mm Rbm 2.5 (0.0-12.7), 3.4 (0.0-8.1) and 1.0 (0.0-6.3) vs. 0.0 (0.0-7.0), p<0.05]. Percentage of vessels stained was also increased in these clinical groups. Preliminary data suggest that in current smoking COPD subjects endothelial cells and cells in the Rbm stain positively for phosphorylated Smad2/3 suggesting TGF-β1 is functionally active in this situation. CONCLUSIONS/SIGNIFICANCE: Vessel-associated TGF-β1 activity is increased in the bronchial Rbm in smokers and especially those with COPD
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
β-Diversity and Species Accumulation in Antarctic Coastal Benthos: Influence of Habitat, Distance and Productivity on Ecological Connectivity
High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in β-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models) to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and β–diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on β-diversity at scales <290 km, while the effects of productivity were low and significant only at scales >40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance
Knowledge about complementary, alternative and integrative medicine (CAM) among registered health care providers in Swedish surgical care: a national survey among university hospitals
<p>Abstract</p> <p>Background</p> <p>Previous studies show an increased interest and usage of complementary and alternative medicine (CAM) in the general population and among health care workers both internationally and nationally. CAM usage is also reported to be common among surgical patients. Earlier international studies have reported that a large amount of surgical patients use it prior to and after surgery. Recent publications indicate a weak knowledge about CAM among health care workers. However the current situation in Sweden is unknown. The aim of this study was therefore to explore perceived knowledge about CAM among registered healthcare professions in surgical departments at Swedish university hospitals.</p> <p>Method</p> <p>A questionnaire was distributed to 1757 registered physicians, nurses and physiotherapists in surgical wards at the seven university hospitals in Sweden from spring 2010 to spring 2011. The questionnaire included classification of 21 therapies into conventional, complementary, alternative and integrative, and whether patients were recommended these therapies. Questions concerning knowledge, research, and patient communication about CAM were also included.</p> <p>Result</p> <p>A total of 737 (42.0%) questionnaires were returned. Therapies classified as complementary; were massage, manual therapies, yoga and acupuncture. Alternative therapies; were herbal medicine, dietary supplements, homeopathy and healing. Classification to integrative therapy was low, and unfamiliar therapies were Bowen therapy, iridology and Rosen method. Therapies recommended by > 40% off the participants were massage and acupuncture. Knowledge and research about CAM was valued as minor or none at all by 95.7% respectively 99.2%. Importance of possessing knowledge about it was valued as important by 80.9%. It was believed by 61.2% that more research funding should be addressed to CAM research, 72.8% were interested in reading CAM-research results, and 27.8% would consider taking part in such research. Half of the participants (55.8%) were positive to learning such therapy. Communication about CAM between patients and the health care professions was found to be rare.</p> <p>Conclusion</p> <p>There is a lack of knowledge about CAM and research about it among registered health care professions in Swedish surgical care. However, in contrast to previous studies the results revealed that the majority perceived it as important to gain knowledge in this field.</p
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