11 research outputs found

    ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider

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    Elemental and isotope fingerprint of metal deficiency in soils

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    Metal deficiency in soils is a frequently observed phenomenon in (sub)-tropical regions, and both natural and anthropogenic processes contribute to the depletion of soil reservoirs. Advanced chemical weathering, in old regolith, can lead to very severe natural depletion of metals in certain soil types, while soil over-cropping represents the human impact that increases the net offtake of metals from many soils. In both cases, the health of humans can suffer since many trace metals have vital functions in the human body. For example, nearly half the world population is affected by Zn deficiency symptoms caused by over-dependence on local crops that are grown on Zn deficient soils. This is all the more concerning in view of the anticipated rise in world population that will put additional demands on crop production with likely knock-on effects for essential metal depletion in soil. This thesis presents petrographic, mineralogical and geochemical as well as isotopic investigations of two contrasting weathering profiles from the Deccan Traps, India to investigate the natural causes of metal deficiency in soils. Major- and trace elements (including essential metals), organic carbon (C) content, chemical weathering indices, uranium-series (U-series) systematics as well as zinc (Zn)- and chromium (Cr)- isotopes were analysed to quantify the mineralogical transformations, biogeochemical processes and environmental factors that lead to the loss of metals during soil formation. In addition, agricultural topsoil and animal manure samples were investigated from Zn deficient regions in India to compare and contrast their biogeochemical fingerprints to the findings from the weathering profiles. The work revealed that actively weathering soils are strongly depleted in the isotope 234U, hosted in labile sites in minerals. The chemical breakdown of metal-rich primary silicates and clay minerals in saprolite results in the mobilisation of substantial amounts of metals to aqueous solutions and plants. Ultimately, the breakdown of these minerals contributes to oceanic metal inventories, exemplified by the excess of 234U in seawater. By contrast, strongly weathered soils (i.e. laterites) have lost their natural capacity to supply bio-available forms of metals to the environment and concentrations of residual essential metals such as Zn or redistributed Cr are mainly hosted in weathering resistant iron (Fe)-oxides. The isotopic fractionation of Zn and Cr is strongly affected by the formation of Fe-oxides, whereas the metal stable isotope ratios in actively weathering saprolite remain in the range of unweathered bedrocks. Hence, Zn isotopes can be used to distinguish between fertile and Zn deficient soils. Importantly, the geochemical fingerprints in the agricultural topsoils reveal that high concentrations of essential metals (Zn, copper (Cu), cobalt (Co), nickel (Ni), Cr) are also hosted in bio-unavailable oxide phases, whereas the bio-available pool in the inorganic soil constituents is much lower. Since the bio-available concentrations of metals in animal manure are too low to counterbalance essential metal deficiencies in Indian soils, their fertility status remains delicate without application of industrial metal fertilisers. Overall, the findings of this thesis suggest that geochemical and isotopic data can contribute to a deeper understanding of metal deficiency in soils and help in the development of more sustainable farming practices in (sub)-tropical regions

    Silicon and chromium stable isotopic systematics during basalt weathering and lateritisation: A comparison of variably weathered basalt profiles in the Deccan Traps, India

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    Global biomass production is fundamentally affected by the hydrological cycling of elements at the Earth?s surface. Continental weathering processes are the major source for most bio-essential elements in marine environments and therefore affect primary productivity. In addition, critical zone biomass depends on energy and chemical exchange reactions in weathering profiles. The latter reservoirs are in turn influenced by different climatic conditions that control weathering and pore water parameters like pH and Eh, these then regulate mineral break down rates that dictate the mobility and mass flux of elements. Two Deccan Trap basalt-weathering profiles of contrasting age and alteration intensity provide a natural laboratory for investigating the effects of rock alteration on Si and Cr and their isotopic systematics. The sub-recent Chhindwara profile has progressed to a moderate degree of alteration (saprolite), whilst the Paleogene Bidar example displays an extremely altered laterite. The Chhindwara profile shows a near uniform Cr and Si concentration and isotopic composition, whereas the Bidar profile is characterised by an intense loss of Si, a large enrichment of Cr within the most altered uppermost levels, and a wide range of Cr stable isotope ratios (-0.85 to 0.36 ? ?53/52Cr). A co-variation between Si and Cr isotopes, as well as their co-variation with iron content, provides empirical evidence that iron redistribution within the profile has a large effect on Cr mobility. Therefore, it is concluded that iron oxides exert a primary control over the isotopic composition of both Cr and Si in pore waters of laterites. Because laterite formation is promoted by tropical climates, the results of this study provide new evidence to suggest that the hydrological Cr and Si fluxes originating from continental weathering have changed in accordance with large-scale, deep time climate variation and continental plate configuration. An increased flux of Si and greater magnitude of Cr mobility and isotopic fractionation are possibly amplified under CO2-rich, greenhouse episodes and/or when large landmasses were tectonically arranged at near equatorial latitudes

    Search for Scalar Diphoton Resonances in the Mass Range 6560065-600 GeV with the ATLAS Detector in pppp Collision Data at s\sqrt{s} = 8 TeVTeV

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    A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using 20.3fb120.3\text{}\text{}{\mathrm{fb}}^{-1} of s=8TeV\sqrt{s}=8\text{}\text{}\mathrm{TeV} pppp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches

    Search for Higgs and ZZ Boson Decays to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma with the ATLAS Detector

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    A search for the decays of the Higgs and ZZ bosons to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma (n=1,2,3n=1,2,3) is performed with pppp collision data samples corresponding to integrated luminosities of up to 20.3fb120.3\mathrm{fb}^{-1} collected at s=8TeV\sqrt{s}=8\mathrm{TeV} with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above expected backgrounds and 95% CL upper limits are placed on the branching fractions. In the J/ψγJ/\psi\gamma final state the limits are 1.5×1031.5\times10^{-3} and 2.6×1062.6\times10^{-6} for the Higgs and ZZ bosons, respectively, while in the Υ(1S,2S,3S)γ\Upsilon(1S,2S,3S)\,\gamma final states the limits are (1.3,1.9,1.3)×103(1.3,1.9,1.3)\times10^{-3} and (3.4,6.5,5.4)×106(3.4,6.5,5.4)\times10^{-6}, respectively

    Finska tingsdomares bedömningar av partsutlåtanden givna på plats i rätten eller via videokonferens

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    Professionals within the judicial system sometimes believe they can assess whether someone is lying or not based on cues such as body language and emotional expression. Research has, however, shown that this is impossible. The Finnish Supreme Court has also given rulings in accordance with this demonstrated fact. There has also been previous research on whether party or witness statements are assessed differently in court depending on whether they are given live, via videoconference, or via prerecorded video. In the present study, we investigated how a Finnish sample of district judges (N=47) assigned probative value to different variables concerning the statement or the statement giver, such as body language and emotional expression. We also investigated the connection between the judges’ beliefs about the relevance of body language and emotional expression and their preference for live statements or statements via videoconference. The judges reported assigning equal amounts of probative value to statements given live and statements given via videoconference. However, judges found it easier to detect deception live, and this preference correlated with how relevant they thought body language is when assessing the probative value of the statement. In other words, a slight bias to assess live statements more favorably than statements given via videoconference might still exist. More effort needs to be put into making judges and Supreme Courts aware of robust scientific results that have been the subject of decades of research, such as the fact that one cannot assess whether someone is lying or not based on cues such as body language

    Search for Scalar-Charm pair production in pp collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    The results of a dedicated search for pair production of scalar partners of charm quarks are reported. The search is based on an integrated luminosity of 20.3 fb1^{-1} of pp collisions at s=8\sqrt{s}=8 TeV recorded with the ATLAS detector at the LHC. The search is performed using events with large missing transverse momentum and at least two jets, where the two leading jets are each tagged as originating from c-quarks. Events containing isolated electrons or muons are vetoed. In an R-parity-conserving minimal supersymmetric scenario in which a single scalar-charm state is kinematically accessible, and where it decays exclusively into a charm quark and a neutralino, 95% confidence-level upper limits are obtained in the scalar-charm-neutralino mass plane such that, for neutralino masses below 200 GeV, scalar-charm masses up to 490 GeV are excluded

    Search for Higgs and Z Boson Decays to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma with the ATLAS Detector

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    A search for the decays of the Higgs and Z bosons to J/ψγ and ϒ(nS)γ (n=1,2,3) is performed with pp collision data samples corresponding to integrated luminosities of up to 20.3 fb-1 collected at s=8 TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above expected backgrounds and 95% C.L. upper limits are placed on the branching fractions. In the J/ψγ final state the limits are 1.5×10-3 and 2.6×10-6 for the Higgs and Z boson decays, respectively, while in the ϒ(1S,2S,3S)γ final states the limits are (1.3,1.9,1.3)×10-3 and (3.4,6.5,5.4)×10-6, respectively

    Measurement of differential J/ψJ/\psi production cross-sections and forward-backward ratio in p+Pb collisions with the ATLAS detector

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    Measurements of differential cross-sections for J/ψJ/\psi production in p+Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV at the LHC with the ATLAS detector are presented. The data set used corresponds to an integrated luminosity of 28.1 nb1^{-1}. The J/ψJ/\psi mesons are reconstructed in the dimuon decay channel over the transverse momentum range 8<pT<308<p_{\mathrm{T}}<30 GeV and over the center-of-mass rapidity range 2.87<y<1.94-2.87<y^{*}<1.94. Prompt J/ψJ/\psi are separated from J/ψJ/\psi resulting from bb-hadron decays through an analysis of the distance between the J/ψJ/\psi decay vertex and the event primary vertex. The differential cross-section for production of nonprompt J/ψJ/\psi is compared to a FONLL calculation that does not include nuclear effects. Forward-backward production ratios are presented and compared to theoretical predictions. These results constrain the kinematic dependence of nuclear modifications of charmonium and bb-quark production in p+Pb collisions

    Measurements of the Total and Differential Higgs Boson Production Cross Sections Combining the H??????? and H???ZZ*???4??? Decay Channels at s\sqrt{s}=8??????TeV with the ATLAS Detector

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    Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3~fb1^{-1} of pppp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8\sqrt{s} = 8 TeV and recorded by the ATLAS detector. Cross sections are obtained from measured HγγH \rightarrow \gamma \gamma and HZZ4H \rightarrow ZZ ^{*}\rightarrow 4\ell event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σppH=33.0±5.3(stat)±1.6(sys)pb\sigma_{pp \to H} = 33.0 \pm 5.3 \, ({\rm stat}) \pm 1.6 \, ({\rm sys}) \mathrm{pb}. The measurements are compared to state-of-the-art predictions.Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3  fb-1 of pp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8  TeV and recorded by the ATLAS detector. Cross sections are obtained from measured H→γγ and H→ZZ*→4ℓ event yields, which are combined accounting for detector efficiencies, fiducial acceptances, and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σpp→H=33.0±5.3 (stat)±1.6 (syst)  pb. The measurements are compared to state-of-the-art predictions.Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb1^{-1} of pppp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8\sqrt{s} = 8 TeV and recorded by the ATLAS detector. Cross sections are obtained from measured HγγH \rightarrow \gamma \gamma and HZZ4H \rightarrow ZZ ^{*}\rightarrow 4\ell event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σppH=33.0±5.3(stat)±1.6(sys)pb\sigma_{pp \to H} = 33.0 \pm 5.3 \, ({\rm stat}) \pm 1.6 \, ({\rm sys}) \mathrm{pb}. The measurements are compared to state-of-the-art predictions
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