207 research outputs found

    The Asymptotic Giant Branches of GCs: Selective Entry Only

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    The handful of available observations of AGB stars in Galactic Globular Clusters suggest that the GC AGB populations are dominated by cyanogen-weak stars. This contrasts strongly with the distributions in the RGB (and other) populations, which generally show a 50:50 bimodality in CN band strength. If it is true that the AGB populations show very different distributions then it presents a serious problem for low mass stellar evolution theory, since such a surface abundance change going from the RGB to AGB is not predicted by stellar models. However this is only a tentative conclusion, since it is based on very small AGB sample sizes. To test whether this problem really exists we have carried out an observational campaign specifically targeting AGB stars in GCs. We have obtained medium resolution spectra for about 250 AGB stars across 9 Galactic GCs using the multi-object spectrograph on the AAT (2df/AAOmega). We present some of the preliminary findings of the study for the second parameter trio of GCs: NGC 288, NGC 362 and NGC 1851. The results indeed show that there is a deficiency of stars with strong CN bands on the AGB. To confirm that this phenomenon is robust and not just confined to CN band strengths and their vagaries, we have made observations using FLAMES/VLT to measure elemental abundances for NGC 6752.We present some initial results from this study also. Our sodium abundance results show conclusively that only a subset of stars in GCs experience the AGB phase of evolution. This is the first direct, concrete confirmation of the phenomenon.Comment: 4 pages, to appear in conference proceedings of "Reading the book of globular clusters with the lens of stellar evolution", Rome, 26-28 November 201

    Phylogenetic inference using cytochrome c oxidase subunit I (COI) in the poultry red mite, Dermanyssus gallinae in the United Kingdom relative to a European framework

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    The poultry red mite (Dermanyssus gallinae), an obligatory blood feeding ectoparasite, is primarily associated with laying hens where it is estimated to cause losses of ~€231 million per annum to European farmers. Moderate to high infestation levels result in negative impacts on hen welfare, including increased cannibalism, irritation, feather pecking, restlessness, anaemia and mortality. Acaricides are currently the prevailing method of population control for D. gallinae, although resistance against some classes of acaricide has been widely reported. The development of resistance highlights a growing need for research into alternative control methods, including the development of a suitable and effective vaccine. Understanding the genetic structure of D. gallinae populations can support improved management of acaricide resistance and sustainability of future vaccines, but limited data are currently available. The aim of this study was to characterise D. gallinae isolates from Europe, targeting the cytochrome c oxidase subunit 1 (COI) gene to gain an insight into population structure and genetic diversity of currently circulating mites. Dermanyssus gallinae isolates were collected from Albania, Belgium, Croatia, Czech Republic, Denmark, France, Greece, Italy, the Netherlands, Portugal, Romania, Slovenia, Turkey and the United Kingdom. Genomic DNA was extracted from individual adult D. gallinae mites and a 681bp fragment of the COI gene was amplified and sequenced. Phylogenetic analyses of 195 COI sequences confirmed the presence of multiple lineages across Europe with 76 distinct haplotypes split across three main haplogroups and six sub-haplogroups. Importantly there is considerable inter- and intra-country variation across Europe, which could result from the movement of poultry or transfer of contaminated equipment and/or materials and husbandry practices

    Corynebacterium jeikeium bacteremia in a hemodialyzed patient

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    SummaryCorynebacterium jeikeium, frequently encountered in clinical specimens, is part of the normal skin flora. Nevertheless, a few cases of C. jeikeium bacteremia followed by severe clinical manifestations have been reported. C. jeikeium has been reported to cause endocarditis, septicemia, meningitis, pneumonia and osteomyelitis, along with soft tissue and trauma infections. Herein we describe a case of C. jeikeium bacteremia in Greece. The isolation of a coryneform bacterium from a clinical specimen should not immediately be considered a superinfection by the skin flora. Clinical and laboratory investigations are essential in order to evaluate such cases before applying appropriate treatment. On the other hand, the association of coryneform bacteria and disease should be critically investigated, with a thorough identification of the strain, ideally beyond the classical methods, at a specialized center

    Factors affecting the effectiveness of the pick and roll offense at the 2017 European Men's Championship

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    Abstract The evolution of basketball made the game faster, leading coaches to increase the use of pick and roll cooperation in offense. The purpose of this research was to investigate the performance time of the pick and roll every five minutes, the pair of players who participated in the pick and roll and the offensive action of the ball handler after the screen, in the European Men's Championship of 2017. The sample of the research was the sixteen games of the second round of the Championship. The instrument used for the analysis of the matches was the SportScout STA Version 3.2. Analysis with ê­“2 (Chi-square) was used. In the results analysis, a total of 714 screens were found, of which 356 were successful (49.9%) and 358 (50.1%) failed. Most pick and rolls were performed in the second five-minute span of the third period of the games (14.8%) and in the first five-minute span of the first period (14.1%). Regarding the pairs of players participating in the action, most of them had the guard as the ball handler and the center as the screener (63.4%). In about 60% of the pick and rolls the ball handler chose to finish the action himself either by driving to the basket (31.8%) or with a shot (28.6%). The results of this study provide more information and directions to basketball coaches in order for them to better organize their training and maximize the offensive performance of their teams

    Effect of shot peening on the residual stress and mechanical behaviour of low-temperature and high-temperature annealed martensitic gear steel 18CrNiMo7-6

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    A martensitic gear steel (18CrNiMo7-6) was annealed at 180 \ub0C for 2h and at ∼ 750 \ub0C for 1h to design two different starting microstructures for shot peening. One maintains the original as-transformed martensite while the other contains irregular-shaped sorbite together with ferrite. These two materials were shot peened using two different peening conditions. The softer sorbite + ferrite microstructure was shot peened using 0.6 mm conditioned cut steel shots at an average speed of 25 m/s in a conventional shot peening machine, while the harder tempered martensite steel was shot peened using 1.5 mm steel shots at a speed of 50 m/s in an in-house developed shot peening machine. The shot speeds in the conventional shot peening machine were measured using an in-house lidar set-up. The microstructure of each sample was characterized by optical and scanning electron microscopy, and the mechanical properties examined by microhardness and tensile testing. The residual stresses were measured using an Xstress 3000 G2R diffractometer equipped with a Cr Kα x-ray source. The correspondence between the residual stress profile and the gradient structure produced by shot peening, and the relationship between the microstructure and strength, are analyzed and discussed

    The motion of trees in the wind: a data synthesis

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    Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees, and wind is a key disturbance agent in many of the world\u27s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically important, rather than broadleaf forests, which dominate the forest carbon cycle. This study brings together tree motion time-series data to systematically evaluate the factors influencing tree responses to wind loading, including data from both broadleaf and coniferous trees in forests and open environments. We found that the two most descriptive features of tree motion were (a) the fundamental frequency, which is a measure of the speed at which a tree sways and is strongly related to tree height, and (b) the slope of the power spectrum, which is related to the efficiency of energy transfer from wind to trees. Intriguingly, the slope of the power spectrum was found to remain constant from medium to high wind speeds for all trees in this study. This suggests that, contrary to some predictions, damping or amplification mechanisms do not change dramatically at high wind speeds, and therefore wind damage risk is related, relatively simply, to wind speed. Conifers from forests were distinct from broadleaves in terms of their response to wind loading. Specifically, the fundamental frequency of forest conifers was related to their size according to the cantilever beam model (i.e. vertically distributed mass), whereas broadleaves were better approximated by the simple pendulum model (i.e. dominated by the crown). Forest conifers also had a steeper slope of the power spectrum. We interpret these finding as being strongly related to tree architecture; i.e. conifers generally have a simple shape due to their apical dominance, whereas broadleaves exhibit a much wider range of architectures with more dominant crowns

    Spatial-spectral flexible optical networking:enabling switching solutions for a simplified and efficient SDM network platform

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    The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution

    Cyanogen in NGC 1851 red giant branch and asymptotic giant branch stars: Quadrimodal distributions

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    The Galactic globular cluster NGC 1851 has raised much interest since Hubble Space Telescope photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) band strengths in the red giant branc
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