65 research outputs found

    GIS Applications on the Essential Public Services in Mozambique

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    A thesis submitted in partial fulfillment of the requirements for the degree of Doctor in Information Management, specialization in Geographic Information SystemsWater supply and health are considered essential public services and are therefore a fundamental right for human development. The use of GIS in public services has had a tremendous growth as result of the availability of various information technology services and software, and is currently being considered useful to the understanding and treatment of health problems in different geographic areas and and optimize the locations of infrastructure and public services. The aim of this study is to measure the geographic accessibility of population to existing healthcare centers, and find the most suitable locations for small dams/water reservoirs in the Tete province region, Mozambique, which has a pronounced water deficit. The objectives were achieved using the GIS approach, where accessibility to health services was first measured using travel time and driving scenarios to the health centers. On the other hand, to find the most suitable locations for small dams / reservoirs a multi-criteria evaluation (MCE) analysis through an Analytic Hierarchical Process (AHP) were implemented, including local experts ’consultation. The study consider 9 criteria including slope, elevation, rainfall, stream density, lineaments, soil, land-use, distance to roads and distance to villages as the most important criteria in locating a dam.Findings from this study highlight accessibility problems, especially in the walking scenario, in which 90.2% of Mozambique was considered an underserved area. In this scenario, Maputo City (69.8%) is the province with the greatest coverage of HC. On the other hand, Tete (93.4%), Cabo Delgado (93%) and Gaza (92.8%) are the provinces with the most underserved areas. The driving scenario was less problematic, with about 66.9 % of Mozambique being considered a served area. For dam/reservoir site location study, the results show three main categories of suitability: “Not suitable” (15% of total area), “Modestly suitable” (78%), and “Suitable” (7%). We found that 92% abandoned small dams/reservoirs were in areas classified as “Modestly suitable” confirming the robustness of our model. We also found that most of the dams/reservoirs currently operating (78%) and planned (73%) are in modestly suitable areas. This finding suggests that the decision to construct dams/reservoirs may not have considered the most critical suitability factors identified in this study. The mapped outputs may have policy implications and could be used for future decision-making processes and analysis for both the health and water resources managemen

    Performance of the ATLAS Track Reconstruction Algorithms in Dense Environments in LHC Run 2

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    With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13  TeV\text {TeV} for Run 2, events with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb1^{-1} of data collected by the ATLAS experiment and simulation of proton–proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13  TeV\text {TeV} . The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 GeV\text {GeV} is quantified using a novel, data-driven, method. The method uses the energy loss,  dE/dx{\text { d}}{} \textit{E}/d\textit{x} , to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is 0.061±0.006 (stat.)±0.014 (syst.)0.061 \pm 0.006\ {\text {(stat.)}} \pm 0.014\ {\text {(syst.)}} and 0.093±0.017 (stat.)±0.021 (syst.)0.093 \pm 0.017\ {\text {(stat.)}}\pm 0.021\ {\text {(syst.)}} for jet transverse momenta of 200–400  GeV\text {GeV} and 1400–1600  GeV\text {GeV} , respectively.Peer Reviewe

    Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13\sqrt{s}=13\, TeV using the ATLAS detector

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    Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and tt¯ system kinematic observables using proton-proton collisions at a center-of-mass energy of s=13  TeV. The data set corresponds to an integrated luminosity of 36.1  fb-1, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum pT>500  GeV and a second with pT>350  GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a b-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated χ2 values. The cross-section for tt¯ production in the fiducial phase-space region is 292±7(stat)±71(syst)  fb, to be compared to the theoretical prediction of 384±36  fb.Peer Reviewe

    Measurement of charged-particle distributions sensitive to the underlying event in s=13 \sqrt{s}=13 TeV proton-proton collisions with the ATLAS detector at the LHC

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    We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV, in low-luminosity Large Hadron Collider fills corresponding to an integrated luminosity of 1.6 nb1^{−1}. The distributions were constructed using charged particles with absolute pseudorapidity less than 2.5 and with transverse momentum greater than 500 MeV, in events with at least one such charged particle with transverse momentum above 1 GeV. These distributions characterise the angular distribution of energy and particle flows with respect to the charged particle with highest transverse momentum, as a function of both that momentum and of charged-particle multiplicity. The results have been corrected for detector effects and are compared to the predictions of various Monte Carlo event generators, experimentally establishing the level of underlying-event activity at LHC Run 2 energies and providing inputs for the development of event generator modelling. The current models in use for UE modelling typically describe this data to 5% accuracy, compared with data uncertainties of less than 1%.Peer Reviewe

    Measurement of the cross section for isolated-photon plus jet production in pppp collisions at s=13\sqrt s=13 TeV using the ATLAS detector

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    The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb −1 . Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- kt algorithm with radius parameter R=0.4 and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements.Peer Reviewe

    Measurement of the inclusive jet cross-sections in proton-proton collisions at s=8 \sqrt{s}=8 TeV with the ATLAS detector

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    Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of s=8 \sqrt{s}=8 TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb1^{−1}. Double-differential cross-sections are measured for jets defined by the anti-kt_{t} jet clustering algorithm with radius parameters of R = 0.4 and R = 0.6 and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed.Peer Reviewe

    Measurements of top-quark pair differential cross-sections in the eμe\mu channel in pppp collisions at s=13\sqrt{s} = 13 TeV using the ATLAS detector

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    This article presents measurements of ttˉt\bar{t} differential cross-sections in a fiducial phase-space region, using an integrated luminosity of 3.2 fb1^{-1} of proton–proton data at a centre-of-mass energy of s=13\sqrt{s} = 13  TeV recorded by the ATLAS experiment at the LHC in 2015. Differential cross-sections are measured as a function of the transverse momentum and absolute rapidity of the top quark, and of the transverse momentum, absolute rapidity and invariant mass of the ttˉt\bar{t} system. The ttˉt\bar{t} events are selected by requiring one electron and one muon of opposite electric charge, and at least two jets, one of which must be tagged as containing a b-hadron. The measured differential cross-sections are compared to predictions of next-to-leading order generators matched to parton showers and the measurements are found to be consistent with all models within the experimental uncertainties with the exception of the Powheg-Box ++ Herwig++ predictions, which differ significantly from the data in both the transverse momentum of the top quark and the mass of the ttˉt\bar{t} system.Peer Reviewe

    Search for dark matter in association with a Higgs boson decaying to bb-quarks in pppp collisions at s=13\sqrt s=13 TeV with the ATLAS detector

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    A search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks is presented, using 3.2 fb −1 of pp collisions at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum bb¯ system with either a pair of small-radius jets, or a single large-radius jet with substructure. The observed data are found to be consistent with the expected backgrounds. Results are interpreted using a simplified model with a Z′ gauge boson mediating the interaction between dark matter and the Standard Model as well as a two-Higgs-doublet model containing an additional Z′ boson which decays to a Standard Model Higgs boson and a new pseudoscalar Higgs boson, the latter decaying into a pair of dark matter particles.Peer Reviewe

    A search for top squarks with R-parity-violating decays to all-hadronic final states with the ATLAS detector in s\sqrt{s} = 8 TeV proton-proton collisions

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    A search for the pair production of top squarks, each with R-parity-violating decays into two Standard Model quarks, is performed using 17.4 fb1^{−1} of s=8 \sqrt{s}=8 TeV proton-proton collision data recorded by the ATLAS experiment at the LHC. Each top squark is assumed to decay to a b- and an s-quark, leading to four quarks in the final state. Background discrimination is achieved with the use of b-tagging and selections on the mass and substructure of large-radius jets, providing sensitivity to top squark masses as low as 100 GeV. No evidence of an excess beyond the Standard Model background prediction is observed and top squarks decaying to bs \overline{b}\overline{s} are excluded for top squark masses in the range 100 mt 315 100\ \le {m}_{\overline{t}}\le\ 315 GeV at 95% confidence level.Peer Reviewe

    The performance of the jet trigger for the ATLAS detector during 2011 data taking

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    The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction.Peer Reviewe
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