480 research outputs found
Patterns of genetic diversity in three plant lineages endemic to the Cape Verde Islands
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. The file attached is the published version of the article
A Deep Multiwavelength View of Binaries in Omega Centauri
We summarize results of a search for X-ray-emitting binary stars in the
massive globular cluster Omega Centauri (NGC 5139) using Chandra and HST.
ACIS-I imaging reveals 180 X-ray sources, of which we estimate that 45-70 are
associated with the cluster. We present 40 identifications, most of which we
have obtained using ACS/WFC imaging with HST that covers the central 10'x10' of
the cluster. Roughly half of the optical IDs are accreting binary stars,
including 9 very faint blue stars that we suggest are cataclysmic variables
near the period limit. Another quarter comprise a variety of different systems
all likely to contain coronally active stars. The remaining 9 X-ray-bright
stars are an intriguing group that appears redward of the red giant branch,
with several lying along the anomalous RGB. Future spectroscopic observations
should reveal whether these stars are in fact related to the anomalous RGB, or
whether they instead represent a large group of "sub-subgiants" such as have
been seen in smaller numbers in other globular and open clusters.Comment: 6 pages, 2 figures, to appear in the proceedings of the conference
"Binary Star Evolution: Mass Loss, Accretion, and Mergers," Mykonos, Greece,
June 22-25, 201
Sources of variation in small rodent trophic niche: New insights from DNA metabarcoding and stable isotope analysis
Intraspecific competition for food is expected to increase the trophic niche width of consumers, defined here as their diet diversity, but this process has been little studied in herbivores. Population densities of small rodents fluctuate greatly, providing a good study model to evaluate effects of competition on trophic niche. We studied resource use in five arctic small rodent populations of four species combining DNA metabarcoding of stomach contents and stable isotope analysis (SIA). Our results suggest that for small rodents, the most pronounced effect of competition on trophic niche is due to increased use of secondary habitats and to habitat-specific diets, rather than an expansion of trophic niche in primary habitat. DNA metabarcoding and SIA provided complementary information about the composition and temporal variation of herbivore diets. Combing these two approaches requires caution, as the underlying processes causing observed patterns may differ between methodologies due to different spatiotemporal scales.
The final version of this research has been published in Isotopes in Environmental and Health Studies. © 2014 Taylor & Franci
Analysing diet of small herbivores: the efficiency of DNA barcoding coupled with high-throughput pyrosequencing for deciphering the composition of complex plant mixtures
Background
In order to understand the role of herbivores in trophic webs, it is essential to know what they feed on. Diet analysis is, however, a challenge in many small herbivores with a secretive life style. In this paper, we compare novel (high-throughput pyrosequencing) DNA barcoding technology for plant mixture with traditional microhistological method. We analysed stomach contents of two ecologically important subarctic vole species, Microtus oeconomus and Myodes rufocanus, with the two methods. DNA barcoding was conducted using the P6-loop of the chloroplast trnL (UAA) intron.
Results
Although the identified plant taxa in the diets matched relatively well between the two methods, DNA barcoding gave by far taxonomically more detailed results. Quantitative comparison of results was difficult, mainly due to low taxonomic resolution of the microhistological method, which also in part explained discrepancies between the methods. Other discrepancies were likely due to biases mostly in the microhistological analysis.
Conclusion
We conclude that DNA barcoding opens up for new possibilities in the study of plant-herbivore interactions, giving a detailed and relatively unbiased picture of food utilization of herbivores
Highly overlapping winter diet in two sympatric lemming species revealed by DNA metabarcoding
Sympatric species are expected to minimize competition by partitioning resources, especially
when these are limited. Herbivores inhabiting the High Arctic in winter are a prime example
of a situation where food availability is anticipated to be low, and thus reduced diet
overlap is expected. We present here the first assessment of diet overlap of high arctic lemmings
during winter based on DNA metabarcoding of feces. In contrast to previous analyses
based on microhistology, we found that the diets of both collared (Dicrostonyx
groenlandicus) and brown lemmings (Lemmus trimucronatus) on Bylot Island were dominated
by Salix while mosses, which were significantly consumed only by the brown lemming,
were a relatively minor food item. The most abundant plant taxon, Cassiope
tetragona, which alone composes more than 50% of the available plant biomass, was not
detected in feces and can thus be considered to be non-food. Most plant taxa that were
identified as food items were consumed in proportion to their availability and none were
clearly selected for. The resulting high diet overlap, together with a lack of habitat segregation,
indicates a high potential for resource competition between the two lemming species.
However, Salix is abundant in the winter habitats of lemmings on Bylot Island and the nonSalix
portion of the diets differed between the two species. Also, lemming grazing impact on
vegetation during winter in the study area is negligible. Hence, it seems likely that the high
potential for resource competition predicted between these two species did not translate
into actual competition. This illustrates that even in environments with low primary productivity
food resources do not necessarily generate strong competition among herbivores
Measurement of the top quark mass using the matrix element technique in dilepton final states
We present a measurement of the top quark mass in ppÂŻ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7ââfbâ1. The matrix element technique is applied to ttÂŻ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of ttÂŻ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84ââGeV
In a New Land:Mobile Phones, Amplified Pressures and Reduced Capabilities
Framed within the theoretical lens of positive and negative security, this paper presents a study of newcomers to Sweden and the roles of mobile phones in the establishment of a new life. Using creative engagement methods through a series of workshops, two researchers engaged 70 adult participants enrolled into further education colleges in Sweden. Group narratives about mobile phone use were captured in creative outputs, researcher observations and notes and were analysed using thematic analysis. Key findings show that the mobile phone offers security for individuals and a safe space for newcomers to establish a new life in a new land as well as capitalising on other spaces of safety, such as maintaining old ties. This usage produces a series of threats and vulnerabilities beyond traditional technological security thinking related to mobile phone use. The paper concludes with recommendations for policies and support strategies for those working with newcomers
Kinned to be Norwegian : transnational adoptees' positioning in relation to whiteness and the negotiation of nationhood
Author's accepted version (postprint).This is an Accepted Manuscript of an article published by John Wiley & Sons Ltd in Nations and Nationalism on 13 April 2019.Available online: https://onlinelibrary.wiley.com/doi/full/10.1111/nana.12525acceptedVersio
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