957 research outputs found

    Quadrupole and octupole collectivity in the semi-magic nucleus 80206Hg126

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    The first low-energy Coulomb-excitation measurement of the radioactive, semi-magic, two proton-hole nucleus 206Hg, was performed at CERN's recently-commissioned HIE-ISOLDE facility. Two γ rays depopulating low-lying states in 206Hg were observed. From the data, a reduced transition strength B(E2;21+→01+)=4.4(6) W.u. was determined, the first such value for an N=126 nucleus south of 208Pb, which is found to be slightly lower than that predicted by shell-model calculations. In addition, a collective octupole state was identified at an excitation energy of 2705 keV, for which a reduced B(E3) transition probability of 30−13+10 W.u. was extracted. These results are crucial for understanding both quadrupole and octupole collectivity in the vicinity of the heaviest doubly-magic nucleus 208Pb, and for benchmarking a number of theoretical approaches in this key region. This is of particular importance given the paucity of data on transition strengths in this region, which could be used, in principle, to test calculations relevant to the astrophysical r-process

    Stock assessments of bream, whiting and flathead (Acanthopagrus australis, Sillago ciliata and Platycephalus fuscus) in South East Queensland

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    Yellowfin bream, sand whiting and dusky flathead are major target species for both commercial and recreational fishers in south east Queensland. Their fishery and regional social and economic importance prompted stock assessments to inform on the sustainability of fishing. The assessments covered both estuarine and ocean-beach waters between Baffle Creek north of Bundaberg and Coolangatta on the Gold Coast. Over the last five years (2013 to 2017), the South East Queensland total harvest for yellowfin bream, sand whiting and dusky flathead averaged 242, 272 and 121 tonnes per year respectively. The catches split for bream was 54 per cent commercial versus 46 per cent recreational, 77 per cent commercial versus 23 per cent recreational for whiting and 36 per cent commercial versus 64 per cent recreational for flathead. The stock assessments used commercial, recreational, charter and indigenous catch, and research data. Inputs to the model included fish harvest sizes (1945 to present), standardised catch rates from commercial net logbook data (1988 to present), and fish age–length data collected from the fishery (2007 to present). All three assessments were challenging due to lack of contrast in the data since the commercial logbook system began in 1988. All three species had been subject to high harvests prior to that year, and commercial catch rates had not varied much since then. In addition, the only available catch rates came from net fishing, which can target whole schools of fish. Net catch rates may be ‘hyperstable’ and not sensitive to trends in fish population size. Bream biomass was estimated to be at 33.8 per cent of unfished biomass. The equilibrium maximum sustainable yield (MSY) was estimated as 420 tonnes per year (commercial and recreational sectors combined, and Moreton and Fraser regions combined). The model indicated that maintenance of a harvest size of 220 t ⁄ yr will recover the biomass to 60 per cent of unfished in about 25 years. A lower harvest of 150 t ⁄ yr would recover to 60 per cent in about 12 years. Whiting biomass in 2017 was estimated as 28.7 per cent of unfished biomass, which is approximately the biomass corresponding to MSY (denoted BMSY). The model’s estimate of equilibrium MSY was 452 t ⁄ yr. Current combined harvest size is approximately equal to the equilibrium harvest at 60 per cent unfished biomass (B60). Rebuilding of the stock from its current level to B60, however, would require the harvest to be reduced, ideally to about 150 t (commercial and recreational sectors combined, and Moreton and Fraser regions combined) to rebuild within about five years. Yearly harvests between 150 and 270 t ⁄ yr would recover the stock more slowly; the midpoint 210 t ⁄ yr would reach B60 in about seven years. The status of flathead is more uncertain than bream and whiting. The precautionary estimate of dusky flathead biomass in the Moreton region in 2017 was between 36 per cent and 39 per cent of unfished spawning biomass, approximately equal to or slightly below BMSY. The estimated MSY was 104 t ⁄ yr to 112 t ⁄ yr, approximately equal to current harvests. Recovery of the spawning stock to 60 per cent in the Moreton region would require the harvest to be reduced, ideally to 63 t ⁄ yr (commercial and recreational sectors combined, Moreton region only) which would recover to B60 within eight years. An intermediate harvest level of 73 t ⁄ yr would reach B60 within 16 years. In the Fraser region, fishing pressure on flathead was lower, and 2017 estimated spawning biomass was 70 per cent of unfished. Although the results for flathead are already precautionary, additional caution may be needed in view of fishing club catch rates which date back to the 1950s and indicate that flathead were already heavily fished by 1988

    Integrating cross-frequency and within band functional networks in resting-state MEG: A multi-layer network approach

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    Neuronal oscillations exist across a broad frequency spectrum, and are thought to provide a mechanism of interaction between spatially separated brain regions. Since ongoing mental activity necessitates the simultaneous formation of multiple networks, it seems likely that the brain employs interactions within multiple frequency bands, as well as cross-frequency coupling, to support such networks. Here, we propose a multi-layer network framework that elucidates this pan-spectral picture of network interactions. Our network consists of multiple layers (frequency-band specific networks) that influence each other via inter-layer (cross-frequency) coupling. Applying this model to MEG resting-state data and using envelope correlations as connectivity metric, we demonstrate strong dependency between within layer structure and inter-layer coupling, indicating that networks obtained in different frequency bands do not act as independent entities. More specifically, our results suggest that frequency band specific networks are characterised by a common structure seen across all layers, superimposed by layer specific connectivity, and inter-layer coupling is most strongly associated with this common mode. Finally, using a biophysical model, we demonstrate that there are two regimes of multi-layer network behaviour; one in which different layers are independent and a second in which they operate highly dependent. Results suggest that the healthy human brain operates at the transition point between these regimes, allowing for integration and segregation between layers. Overall, our observations show that a complete picture of global brain network connectivity requires integration of connectivity patterns across the full frequency spectrum

    Modulation of post-movement beta rebound by contraction force and rate of force development

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    Movement induced modulation of the beta rhythm is one of the most robust neural oscillatory phenomena in the brain. In the preparation and execution phases of movement, a loss in beta amplitude is observed (movement related beta decrease (MRBD)). This is followed by a rebound above baseline on movement cessation (post movement beta rebound (PMBR)). These effects have been measured widely, and recentwork suggests that they may have significant importance. Specifically, they have potential to form the basis of biomarkers for disease, and have been used in neuroscience applications ranging from brain computer interfaces to markers of neural plasticity. However, despite the robust nature of both MRBD and PMBR, the phenomena themselves are poorly understood. In this study, we characterise MRBD and PMBR during a carefully controlled isometric wrist flexion paradigm, isolating two fundamental movement parameters;force output, and the rate of force development (RFD). Our results show that neither altered force output nor RFD has a significant effect on MRBD. In contrast, PMBR was altered by both parameters. Higher force output results in greater PMBR amplitude, and greater RFD results in a PMBR which is higher in amplitude and shorter in duration. These findings demonstrate that careful control of movement parameters cansystematically change PMBR. Further, for temporally protracted movements, the PMBR can be over 7 s in duration. This means accurate control of movement and judicious selection of paradigm parameters are critical in future clinical and basic neuroscientific studies of sensorimotor beta oscillations

    Extracellular ascorbate modulates glutamate dynamics: role of behavioral activation

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    <p>Abstract</p> <p>Background</p> <p>A physiological increase in extracellular ascorbate (AA), an antioxidant vitamin found throughout the striatum, elevates extracellular glutamate (GLU). To determine the role of behavioral arousal in this interaction, microdialysis was used to measure striatal GLU efflux in rats tested in either a lights-off or lights-on condition while reverse dialysis either maintained the concentration of AA at 250 ÎŒM or increased it to 1000 ÎŒM to approximate endogenous changes.</p> <p>Results</p> <p>When lights were off, both locomotion and GLU increased regardless of AA dose. In contrast, animals in the lights-on condition were behaviorally inactive, and infusion of 1000, but not 250, ÎŒM AA significantly increased extracellular GLU. Interestingly, when ambient light returned to the lights-off group, 1000 ÎŒM prolonged the GLU increase relative to the 250 ÎŒM group.</p> <p>Conclusion</p> <p>Our results not only support evidence that elevated striatal AA increases extracellular GLU but also indicate that this effect depends on behavioral state and the corresponding level of endogenous GLU release.</p

    Fusidic acid and clindamycin resistance in community-associated, methicillin-resistant Staphylococcus aureus infections in children of Central Greece

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    <p>Abstract</p> <p>Introduction</p> <p>In Greece, fusidic acid and clindamycin are commonly used for the empiric therapy of suspected staphylococcal infections.</p> <p>Methods</p> <p>The medical records of children examined at the outpatient clinics or admitted to the pediatric wards of the University General Hospital of Larissa, Central Greece, with community-associated staphylococcal infections from January 2003 to December 2009 were reviewed.</p> <p>Results</p> <p>Of 309 children (0-14 years old), 21 (6.8%) had invasive infections and 288 (93.2%) skin and soft tissue infections (SSTIs). Thirty-five patients were ≀30 days of age. The proportion of staphylococcal infections caused by a community-associated methicillin-resistant <it>Staphylococcus aureus </it>(CA-MRSA) isolate increased from 51.5% (69 of 134) in 2003-2006 to 63.4% (111 of 175) in 2007-2009 (<it>P </it>= 0.037). Among the CA-MRSA isolates, 88.9% were resistant to fusidic acid, 77.6% to tetracycline, and 21.1% to clindamycin. Clindamycin resistance increased from 0% (2003) to 31.2% (2009) among the CA-MRSA isolates (<it>P </it>= 0.011). Over the 7-year period, an increase in multidrug-resistant CA-MRSA isolates was observed (<it>P </it>= 0.004). One hundred and thirty-one (93.6%) of the 140 tested MRSA isolates were Panton-Valentine leukocidin-positive. Multilocus sequence typing of 72 CA-MRSA isolates revealed that they belonged to ST80 (n = 61), ST30 (n = 6), ST377 (n = 3), ST22 (n = 1), and ST152 (n = 1). Resistance to fusidic acid was observed in ST80 (58/61), ST30 (1/6), and ST22 (1/1) isolates.</p> <p>Conclusion</p> <p>In areas with high rate of infections caused by multidrug-resistant CA-MRSA isolates, predominantly belonging to the European ST80 clone, fusidic acid and clindamycin should be used cautiously as empiric therapy in patients with suspected severe staphylococcal infections.</p

    Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development.

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    BACKGROUND: We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. RESULTS: The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements. CONCLUSIONS: Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution

    Dynamic recruitment of resting state sub-networks

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    Resting state networks (RSNs) are of fundamental importance in human systems neuroscience with evidence suggesting that they are integral to healthy brain function and perturbed in pathology. Despite rapid progress in this area, the temporal dynamics governing the functional connectivities that underlie RSN structure remain poorly understood. Here, we present a framework to help further our understanding of RSN dynamics. We describe a methodology which exploits the direct nature and high temporal resolution of magnetoencephalography (MEG). This technique, which builds on previous work, extends from solving fundamental confounds in MEG (source leakage) to multivariate modelling of transient connectivity. The resulting processing pipeline facilitates direct (electrophysiological) measurement of dynamic functional networks. Our results show that, when functional connectivity is assessed in small time windows, the canonical sensorimotor network can be decomposed into a number of transiently synchronising sub-networks, recruitment of which depends on current mental state. These rapidly changing sub-networks are spatially focal with, for example, bilateral primary sensory and motor areas resolved into two separate sub-networks. The likely interpretation is that the larger canonical sensorimotor network most often seen in neuroimaging studies reflects only a temporal aggregate of these transient sub-networks. Our approach opens new frontiers to study RSN dynamics, showing that MEG is capable of revealing the spatial, temporal and spectral signature of the human connectome in health and disease

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
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