100 research outputs found

    Durrington Walls to West Amesbury by way of Stonehenge: a major transformation of the Holocene landscape

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    A new sequence of Holocene landscape change has been discovered through an investigation of sediment sequences, palaeosols, pollen and molluscan data discovered during the Stonehenge Riverside Project. The early post-glacial vegetational succession in the Avon valley at Durrington Walls was apparently slow and partial, with intermittent woodland modification and the opening-up of this landscape in the later Mesolithic and earlier Neolithic, though a strong element of pine lingered into the third millennium BC. There appears to have been a major hiatus around 2900 cal BC, coincident with the beginnings of demonstrable human activities at Durrington Walls, but slightly after activity started at Stonehenge. This was reflected in episodic increases in channel sedimentation and tree and shrub clearance, leading to a more open downland, with greater indications of anthropogenic activity, and an increasingly wet floodplain with sedges and alder along the river’s edge. Nonetheless, a localized woodland cover remained in the vicinity of DurringtonWalls throughout the third and second millennia BC, perhaps on the higher parts of the downs, while stable grassland, with rendzina soils, predominated on the downland slopes, and alder–hazel carr woodland and sedges continued to fringe the wet floodplain. This evidence is strongly indicative of a stable and managed landscape in Neolithic and Bronze Age times. It is not until c 800–500 cal BC that this landscape was completely cleared, except for the marshy-sedge fringe of the floodplain, and that colluvial sedimentation began in earnest associated with increased arable agriculture, a situation that continued through Roman and historic times

    Arbitrary finite intersections of doubling measures and applications

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    Using a wide array of machinery from diverse fields across mathematics, we provide a construction of a measure on the real line which is doubling on all nn-adic intervals for any finite list of nNn\in\mathbb{N}, yet not doubling overall. In particular, we extend previous results in the area, where only two coprime numbers nn were allowed, by using substantially new ideas. In addition, we provide several nontrivial applications to reverse H\"older weights, ApA_p weights, Hardy spaces, BMO and VMO function classes, and connect our results with key principles and conjectures across number theory.Comment: 24 pages, 3 figure

    Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

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    This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

    A communal catalogue reveals Earth’s multiscale microbial diversity

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    Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity

    A communal catalogue reveals Earth's multiscale microbial diversity

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    Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Bi-allelic loss-of-function CACNA1B mutations in progressive epilepsy-dyskinesia

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    The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Cav2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca2+ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Cav2.2 in normal human neurodevelopment

    Implications of market integration for cardiovascular and metabolic health among an indigenous Amazonian Ecuadorian population

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    BackgroundMarket integration (MI), the suite of social and cultural changes that occur with economic development, has been associated with negative health outcomes such as cardiovascular disease; however, key questions remain about how this transition manifests at the local level.AimThe present paper investigates the effects of MI on health among Shuar, an indigenous lowland Ecuadorian population, with the goal of better understanding the mechanisms responsible for this health transition.Subjects and methodsThis study examines associations between measures of MI and several dimensions of cardiovascular and metabolic health (fasting glucose, lipids [LDL, HDL and total cholesterol; triglycerides] and blood pressure) among 348 adults.ResultsOverall, Shuar males and females have relatively favourable cardiovascular and metabolic health. Shuar who live closer to town have higher total (p < 0.001) and HDL cholesterol (p < 0.001), while Shuar in more remote regions have higher diastolic blood pressure (p = 0.007). HDL cholesterol is positively associated with consumption of market foods (r = 0.140; p = 0.045) and ownership of consumer products (r = 0.184; p = 0.029).ConclusionsThis study provides evidence that MI among Shuar is not a uniformly negative process but instead produces complex cardiovascular and metabolic health outcomes

    Measurement of the W boson polarisation in ttˉt\bar{t} events from pp collisions at s\sqrt{s} = 8 TeV in the lepton + jets channel with ATLAS

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