2,060 research outputs found

    Rapid retreat of permafrost coastline observed with aerial drone photogrammetry

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    Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500&thinsp;m permafrost coastal reach at high temporal frequency (seven surveys over 40&thinsp;d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5&thinsp;m, more than 6 times faster than the long-term average rate of 2.2±0.1&thinsp;m&thinsp;a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1&thinsp;m&thinsp;d−1 over a single 4&thinsp;d period. Over 40&thinsp;d, we estimated removal of ca. 0.96&thinsp;m3&thinsp;m−1&thinsp;d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.</p

    CsI(Tl) Pulse Shape Discrimination with the Belle II Electromagnetic Calorimeter as a Novel Method to Improve Particle Identification at Electron-Positron Colliders

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    This paper describes the implementation and performance of CsI(Tl) pulse shape discrimination for the Belle II electromagnetic calorimeter, representing the first application of CsI(Tl) pulse shape discrimination for particle identification at an electron-positron collider. The pulse shape characterization algorithms applied by the Belle II calorimeter are described. Control samples of Îł\gamma, ÎŒ+\mu^+, π±\pi^\pm, K±K^\pm and p/pˉp/\bar{p} are used to demonstrate the significant insight into the secondary particle composition of calorimeter clusters that is provided by CsI(Tl) pulse shape discrimination. Comparisons with simulation are presented and provide further validation for newly developed CsI(Tl) scintillation response simulation techniques, which when incorporated with GEANT4 simulations allow the particle dependent scintillation response of CsI(Tl) to be modelled. Comparisons between data and simulation also demonstrate that pulse shape discrimination can be a new tool to identify sources of improvement in the simulation of hadronic interactions in materials. The KL0K_L^0 efficiency and photon-as-hadron fake-rate of a multivariate classifier that is trained to use pulse shape discrimination is presented and comparisons are made to a shower-shape based approach. CsI(Tl) pulse shape discrimination is shown to reduce the photon-as-hadron fake-rate by over a factor of 3 at photon energies of 0.2 GeV and over a factor 10 at photon energies of 1 GeV

    Assessing the influence of the Responsibility to Protect on the UN Security Council during the Arab Spring

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    This article challenges those perspectives which assert first, that the Security Council’s engagement with the Responsibility to Protect (R2P) during the Arab Spring evidences a generally positive trend, and second, that the response to the Arab Spring, particularly Syria, highlights the need for veto restraint. With respect to the first point, the evidence presented in this article suggests that the manner in which R2P has been employed by the Security Council during this period evidences three key trends: first, a willingness to invoke R2P only in the context of Pillar I; second, a pronounced lack of consensus surrounding Pillar III; and third, the persistent prioritisation of national interests over humanitarian concerns. With respect to veto restraint, this article argues that there is no evidence that this idea will have any significant impact on decision-making at the Security Council; the Council’s response to the Arab Spring suggests that national interests continue to trump humanitarian need

    Prevalence of enteropathogenic viruses and molecular characterization of group A rotavirus among children with diarrhea in Dar es Salaam Tanzania

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    Different groups of viruses have been shown to be responsible for acute diarrhea among children during their first few years of life. Epidemiological knowledge of viral agents is critical for the development of effective preventive measures, including vaccines. In this study we determined the prevalence of the four major enteropathogenic viruses - rotavirus, norovirus, adenovirus and astrovirus - was determined in 270 stool samples collected from children aged 0 - 60 months who were admitted with diarrhea in four hospitals in Dar es Salaam, Tanzania, using commercially available ELISA kits. In addition, the molecular epidemiology of group A rotavirus was investigated using reverse transcriptase multiplex polymerase chain reaction (RT-PCR). At least one viral agent was detected in 87/270 (32.2%) of the children. The prevalence of rotavirus, norovirus, adenovirus and astrovirus was 18.1%, 13.7%, 2.6% and 0.4%, respectively. In most cases (62.1%) of viruses were detected in children aged 7-12 months. The G and P types (VP7 and VP4 genotypes respectively) were further investigated in 49 rotavirus ELISA positive samples. G9 was the predominant G type (81.6%), followed by G1 (10.2%) and G3 (0.2%). P[8] was the predominant P type (83.7%), followed by P[6] (0.4%) and P[4] (0.2%). The following G and P types were not detected in this study population; G2, G4, G8 G10, P[9], P[10] and P[11]. The dominating G/P combination was G9P[8], accounting for 39 (90.7%) of the 43 fully characterized strains. Three (6.1%) of the 49 rotavirus strains could not be typed. Nearly one third of children with diarrhea admitted to hospitals in Dar es Salaam had one of the four viral agents. The predominance of rotavirus serotype G9 may have implication for rotavirus vaccination in Tanzania

    The doctrine of the 'responsibility to protect' as a practice of political exceptionalism

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    The consensus on the doctrine of the ‘responsibility to protect’ has replaced ideas of humanitarian intervention with a new vision of the responsibilities that states have to protect their peoples from the most egregious suffering. The contention of this article is that this is a politics of exceptionalism, whereby power is legitimated by reference to its effectiveness in responding to emergency or crisis. By analysing the doctrine in this way, new light is shed on the debate surrounding the responsibility to protect. First, understanding the doctrine in terms of exceptionalism helps explain the paradox of how the doctrine has been assimilated so readily into institutional and state practice without manifesting any greater commitment to international intervention. Second, understanding these new security practices in terms of exceptionalism allows us to move beyond questions of imperialism. Once understood in terms of exceptionalism, it can be shown that the stakes in the debate on the responsibility to protect are restricted not only to relations between states, but also to relations within them: principles of representative government are to be substituted with paternalist and authoritarian visions of state power

    Differential branching fraction and angular analysis of the decay B0→K∗0ÎŒ+Ό−

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    The angular distribution and differential branching fraction of the decay B 0→ K ∗0 ÎŒ + ÎŒ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions

    Observation of the decay Bc→J/ψK+K−π+B_c \rightarrow J/\psi K^+ K^- \pi^+

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    The decay Bc→J/ψK+K−π+B_c\rightarrow J/\psi K^+ K^- \pi^+ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb−1^{-1}. A signal yield of 78±1478\pm14 decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+ decays to that of Bc→J/ψπ+B_c \rightarrow J/\psi \pi^+ decays is measured to be 0.53±0.10±0.050.53\pm 0.10\pm0.05, where the first uncertainty is statistical and the second is systematic.Comment: 18 pages, 2 figure
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