2,083 research outputs found
Winter wren populations show adaptation to local climate
Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λâ=â1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain
Equipment for local hyperthermia therapy of cancer
Rapid improvements in hyperthermia apparatus are being achieved by industrial and university-based research groups that have already led to the marketing of a variety of commercial systems for heat therapy of malignancy. These tissue heating systems employ microwaves, capacitively or inductively coupled radiofrequency current, or high intensity ultrasound to produce controlled local heating of tumor tissues. No single system is superior to others in all applications; each has its limitations
Hydrothermal activity lowers trophic diversity in Antarctic sedimented hydrothermal vents
Sedimented hydrothermal vents are those in which hydrothermal fluid vents through sediment and are among the least studied deep-sea ecosystems. We present a combination of microbial and biochemical data to assess trophodynamics between and within hydrothermally active and off-vent areas of the Bransfield Strait (1050â1647âm depth). Microbial composition, biomass and fatty acid signatures varied widely between and within vent and non-vent sites and provided evidence of diverse metabolic activity. Several species showed diverse feeding strategies and occupied different trophic positions in vent and non-vent areas and stable isotope values of consumers were generally not consistent with feeding structure morphology. Niche area and the diversity of microbial fatty acids reflected trends in species diversity and was lowest at the most hydrothermally active site. Faunal utilisation of chemosynthetic activity was relatively limited but was detected at both vent and non-vent sites as evidenced by carbon and sulphur isotopic signatures, suggesting that the hydrothermal activity can affect trophodynamics over a much wider area than previously thought
The glacial geomorphology of upper GodthÄbsfjord (Nuup Kangerlua) in south-west Greenland
© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps. 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 use, distribution, and reproduction in any medium, provided the original work is properly cited.The Greenland Ice Sheet (GrIS) is known to have experienced widespread retreat over the last century. Information on outlet glacier dynamics, prior to this, are limited due to both a lack of observations and a paucity of mapped or mappable deglacial evidence which restricts our understanding of centennial to millennial timescale dynamics of the GrIS. Here we present glacial geomorphological mapping, for upper GodthÄbsfjord, covering 5800 km 2 at a scale of 1:92,000, using a combination of ASTER GDEM V2, a medium-resolution DEM (error < 10 m horizontal and < 6 m vertical accuracy), panchromatic orthophotographs and ground truthing. This work provides a detailed geomorphological assessment for the area, compiled as a single map, comprising of moraines, meltwater channels, streamlined bedrock, sediment lineations, ice-dammed lakes, trimlines, terraces, gullied sediment and marine limits. Whilst some of the landforms have been previously identified, the new information presented here improves our understanding of ice margin behaviour and can be used for future numerical modelling and landform dating programmes. Data also form the basis for palaeoglaciological reconstructions and contribute towards understanding of the centennial to millennial timescale record of this sector of the GrIS.Peer reviewedFinal Published versio
Laboratory Tests of Scour at a Seawall
A set of medium-scale laboratory tests of wave-induced scour at seawalls has been performed in a flume at HR Wallingford. The methodology is presented along with test conditions and summarized results. The scour depth at the toe of the seawall is highly dependent on the form of wave breaking onto the structure. Sea states where waves plunge directly onto the wall generate jets of water that may penetrate to the seabed and cause a local scour hole immediately adjacent to the seawall. This is a different scouring mechanism to that observed in deeper water and is also absent when the seawall is well within the surf zone and most of the large waves have broken before they reach the seawall. Theoretical limitations are discussed
Construction of temperature compensated constant voltage (VT) curves for super Ni-Cd (tm) cells
Tests to establish current-voltage characteristics at selected temperatures for 9 a-h Super Nickel-Cadmium cells were conducted at Hughes Industrial Electronics Company's Electron Dynamics Division (HIEC/EDD) under sponsorship of NASA/GSFC through their prime spacecraft contractors Fairchild Space (SMEX/SAMPEX) and TRW (TOMSEP). Curves were constructed using techniques established by Webster, Ford, et al, at NASA/GSFC in the late 1960's - early 1970's time period for conventional nickel cadmium cells used on OAO and OSO aircraft. The NASA/GSFC techniques were slightly modified by HIEC/EDD to fit the Super Ni-Cd situation
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Identification of a candidate gene for a QTL for spikelet number per spike on wheat chromosome arm 7AL by high-resolution genetic mapping.
Key messageA high-resolution genetic map combined with haplotype analyses identified a wheat ortholog of rice gene APO1 as the best candidate gene for a 7AL locus affecting spikelet number per spike. A better understanding of the genes controlling differences in wheat grain yield components can accelerate the improvements required to satisfy future food demands. In this study, we identified a promising candidate gene underlying a quantitative trait locus (QTL) on wheat chromosome arm 7AL regulating spikelet number per spike (SNS). We used large heterogeneous inbred families (â> 10,000 plants) from two crosses to map the 7AL QTL to an 87-kb region (674,019,191-674,106,327 bp, RefSeq v1.0) containing two complete and two partial genes. In this region, we found three major haplotypes that were designated as H1, H2 and H3. The H2 haplotype contributed the high-SNS allele in both H1 Ă H2 and H2 Ă H3 segregating populations. The ancestral H3 haplotype is frequent in wild emmer (48%) but rare (~â1%) in cultivated wheats. By contrast, the H1 and H2 haplotypes became predominant in modern cultivated durum and common wheat, respectively. Among the four candidate genes, only TraesCS7A02G481600 showed a non-synonymous polymorphism that differentiated H2 from the other two haplotypes. This gene, designated here as WHEAT ORTHOLOG OF APO1 (WAPO1), is an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1), which affects spikelet number. Taken together, the high-resolution genetic map, the association between polymorphisms in the different mapping populations with differences in SNS, and the known role of orthologous genes in other grass species suggest that WAPO-A1 is the most likely candidate gene for the 7AL SNS QTL among the four genes identified in the candidate gene region
Exploring student participation across different arenas of school life
Much has now been written on student participation at school. Yet a lack of conceptual clarity, contestation over purpose and benefits, and uncertainty about how to culturally embed and effectively facilitate participation in school contexts continue to pose considerable challenges. This article reports the qualitative findings from a largeâscale, mixedâmethod study that sought to explore how participation is perceived and practised in schools. The qualitative phase involved students from Years 7â10 (n = 177) and staff (n = 32) across 10 government and Catholic secondary schools in New South Wales (NSW), Australia. The data demonstrate that considerable efforts are being made in NSW schools to expand opportunities through which students might âparticipateâ, with these explored across three key arenas of school life: the classroom; coâcurricular activities, including formal participatory structures; and informal relational spaces. Although participatory opportunities were largely ad hoc and often dependent upon the approach of individual teachers or school initiatives, differing enactments of childhood and adulthood were identifiable between the three arenas, along with varying expectations in this regard. The classroom emerged as a positive arena at present, and one in which adultâchild relations are beginning to become reconfigured. The coâcurricular arena was much more contested, with the breadth of potential participatory opportunities perhaps distracting from the need to address underlying intergenerational issues. However, informal relational encounters between students and teachers were becoming increasingly egalitarian, and these offer scope for creating the cultural preconditions such that student participation might expand more evenly across school life
Microsurgical Techniques in Cerebral Revascularization
The surgical management of patients with cerebrovascular disease is reviewed. Our approach to the management of extracranial cerebral vasculature is discussed first, and increasingly more complex areas are then presented. Our discussion reviews the applications of carotid endarterectomy, extracranial-intracranial bypass procedures, and vertebral extracranial reconstruction
Magnetic Field Evolution in Merging Clusters of Galaxies
We present initial results from the first 3-dimensional numerical
magnetohydrodynamical (MHD) simulations of magnetic field evolution in merging
clusters of galaxies. Within the framework of idealized initial conditions
similar to our previous work, we look at the gasdynamics and the magnetic field
evolution during a major merger event in order to examine the suggestion that
shocks and turbulence generated during a cluster/subcluster merger can produce
magnetic field amplification and relativistic particle acceleration and, as
such, may play a role in the formation and evolution of cluster-wide radio
halos. The ICM, as represented by the equations of ideal MHD, is evolved
self-consistently within a changing gravitational potential defined largely by
the collisionless dark matter component represented by an N-body particle
distribution. The MHD equations are solved by the Eulerian, finite-difference
code, ZEUS. The particles are evolved by a standard particle-mesh (PM) code. We
find significant evolution of the magnetic field structure and strength during
two distinct epochs of the merger evolution.Comment: 21 pages, 7 figures, Figure 2 is color postscript. Accepted for
publication in Ap
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