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Sökning: WFRF:(Morais Joao) > Naturvetenskap

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1.
  • Carvalho, Joao, et al. (författare)
  • A drill-hole, geological and geophysical data-based 3D model for target generation in Neves-Corvo mine region, Portugal
  • 2022
  • Ingår i: International journal of earth sciences. - : Springer Nature. - 1437-3254 .- 1437-3262. ; 111, s. 403-424
  • Tidskriftsartikel (refereegranskat)abstract
    • The Neves-Corvo world class Iberian Pyrite Belt volcanogenic massive sulphide (VMS) deposit located in southern Portugal, constitutes an important Cu-Zn-Pb active mine. Seven deposits are currently known, among which the Lombador deposit alone has estimated 150 Mt of massive sulphides. The life-time of the mine is dependent on the discovery of new exploration targets and it is vital to have accurate 3D geological models, not only to guide drilling campaigns but also to drive a winning/new strategy, which in the past has led to Semblana and Monte Branco discoveries: geophysical inversion and modelling. Furthermore, 3D geological models can contribute to the understanding of the tectonic and stratigraphic evolution of the region. Therefore, the goal of this study is to produce a realistic 3D geological model of the Neves-Corvo region, as only one model is presently publicly available: the PROMINE model, which includes the study area of this work and extends from Aljustrel to the border with Spain. Lundin Mining has also produced two unpublished, confidential models in 2007 and 2017. The latest Lundin model incorporates the same geophysical data used in this work (2D and 3D seismic reflection and time-domain electromagnetic (TEM) ground loop data) and approximately 7500 surface and underground drill-holes. The model presented in this research has much more detail than the 2012 PROMINE model in the Neves-Corvo region and uses an updated and revised drill-hole database with approximately 8000 drill-holes, revised geological cross-sections built from surface geology and drill-hole logs, new geological outcrop data, petrophysical and reprocessed geophysical data, and is therefore more detailed and accurate than any of the previous models, in particular the 2007 and PROMINE models. Land gravimetric and aeromagnetic data are also available in the study area but were not directly used to build the geological model but rather to investigate and check the model produced. Modelling was performed with industry standard software and the 3D curves resulting from the geological/geophysical interpretation were interpolated using different approaches to respect the hard data (interpretation lines and drill-holes). The resulting 3D stratigraphic surfaces required strong manual editing to respect the interpretation, due to the presence of folds, thrusts and tectonic nappes in the study area. The surfaces were afterwards tied to the drill-holes, resulting in a 3D model with great accuracy and detail in the near mining area and covering a larger area than previously available 3D geological models. The model has three major stratigraphic layers: the Mertola Flysch Formation and the Volcano-Sedimentary Complex (VSC), overlying the Phyllite-Quartzite Formation basement, and also the known VMS deposits (underlying the top of the Lower VSC) geometries according to drill-hole data. In the central part of the study area, where more drill-holes are available, the top of the Lower VSC sequence surface was also built. This approach will contribute to a better exploration drill-hole planning and the generation of new targets for exploration.
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2.
  • Freitas, Felipe F., et al. (författare)
  • Impact of SM parameters and of the vacua of the Higgs potential in gravitational waves detection
  • 2022
  • Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; 2022:3
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we discuss two different phases of a complex singlet extension of the Standard Model (SM) together with an extension that also includes new fermion fields, in particular, a Majoron model equipped with an inverse seesaw mechanism. All considered scenarios contain a global U(1) symmetry and allow for first-order phase transitions while only two of them are strong enough to favour the detection of primordial gravitational waves (GWs) in planned experiments such as LISA. In particular, this is shown to be possible in the singlet extension with a non vanishing real VEV at zero temperature and also in the model with extra fermions. In the singlet extension with no additional fermions, the detection of GWs strongly depends on the U(1) symmetry breaking pattern of the scalar potential at zero temperature. We study for the first time the impact of the precision in the determination of the SM parameters on the strength of the GWs spectrum. It turns out that the variation of the SM parameters such as the Higgs boson mass and top quark Yukawa coupling in their allowed experimental ranges has a notable impact on GWs detectability prospects.
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4.
  • Addazi, Andrea, et al. (författare)
  • Gravitational echoes of lepton number symmetry breaking with light and ultralight Majorons
  • 2023
  • Ingår i: Journal of Cosmology and Astroparticle Physics. - 1475-7516. ; 2023:9
  • Tidskriftsartikel (refereegranskat)abstract
    • We formulate a version of the low-scale Majoron model equipped with an inverse seesaw mechanism featuring lepton-number preserving dimension-6 operators in the scalar potential. Contrary to its dimension-4 counterpart, we find that the model can simultaneously provide light and ultralight Majorons, neutrino masses and their mixing, while featuring strong first-order cosmological phase transitions associated to the spontaneous breaking of the lepton number and the electroweak symmetries in the early Universe. We show by a detailed numerical analysis under which circumstances the model can be probed via the primordial gravitational wave spectrum potentially observable at LISA and other planned facilities. We discuss which implications result for collider physics observables, such as scalar trilinear couplings, the scalar mixing angle and the mass of a new CP-even Higgs boson.
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5.
  • Donis, Daphne, et al. (författare)
  • Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer
  • 2021
  • Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:12, s. 4314-4333
  • Tidskriftsartikel (refereegranskat)abstract
    • To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
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6.
  • Lundström, Jens, 1981-, et al. (författare)
  • Halmstad intelligent home - Capabilities and opportunities
  • 2016
  • Ingår i: Internet of Things Technologies for HealthCare. - Berlin : Springer Berlin/Heidelberg. - 9783319512334 ; , s. 9-15
  • Konferensbidrag (refereegranskat)abstract
    • Research on intelligent environments, such as smart homes, concerns the mechanisms that intelligently orchestrate the pervasive technical infrastructure in the environment. However, significant challenges are to build, configure, use and maintain these systems. Providing personalized services while preserving the privacy of the occupants is also difficult. As an approach to facilitate research in this area, this paper presents the Halmstad Intelligent Home and a novel approach for multioccupancy detection utilizing the presented environment. This paper also presents initial results and ongoing work. © ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2016.
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7.
  • Pires, Ana Elisabete, et al. (författare)
  • The curious case of the Mesolithic Iberian dogs : An archaeogenetic study
  • 2019
  • Ingår i: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 105, s. 116-129
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigated the genetic composition of six Canis remains from western Iberia, directly radiocarbon dated to 7,903-7,570 years (cal BP). They were identified as dogs via their archaeological and depositional context, osteometry, and a high percentage of aquatic diet shared with humans. For comparison, genetic data were obtained from an additional 37 Iberian dog remains from the Neolithic to Late Antiquity, as well as two Palaeolithic and a Chalcolithic Canis identified as wolves. Previous data indicated that dog mtDNA haplogroup A (HgA) is prevalent in extant European dogs ( > 50%), in the Near East and Asia, but rare or absent ( < 10%) in European Canis older than 3,000 years (cal BP). We found a high frequency (83%) of dog HgA in Mesolithic Iberian dog remains. This is the first report of a high frequency of dog HgA in pre-Neolithic Europe. We show that, contrary to the current view, Canis with HgA did not necessarily arrive in Europe from East-Asia. This phylogeographical difference in HgA frequency demonstrates that genetic differentiation was high prior to, or as a consequence of, domestication which may be linked with pre-Neolithic local processes for Iberian wolf domestication. Our results emphasize that knowledge of both ancient wolves' and early dogs' genetic profiles from the European periphery should improve our understanding of the evolution of the European dog.
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8.
  • Bonilla, Cesar, et al. (författare)
  • Collider signatures of vector-like fermions from a flavor symmetric model
  • 2022
  • Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2022:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a model with two Higgs doublets and several SU(2) scalar singlets with a global non-Abelian flavor symmetry Q6× Z2. This discrete group accounts for the observed pattern of fermion masses and mixing angles after spontaneous symmetry breaking. In this scenario only the third generation of fermions get their masses as in the Standard Model (SM). The masses of the remaining fermions are generated through a seesaw-like mechanism. To that end, the matter content of the model is enlarged by introducing electrically charged vector-like fermions (VLFs), right handed Majorana neutrinos and several SM scalar singlets. Here we study the processes involving VLFs that are within the reach of the Large Hadron Collider (LHC). We perform collider studies for vector-like leptons (VLLs) and vector-like quarks (VLQs), focusing on double production channels for both cases, while for VLLs single production topologies are also included. Utilizing genetic algorithms for neural network optimization, we determine the statistical significance for a hypothetical discovery at future LHC runs. In particular, we show that we can not safely exclude VLLs for masses greater than 200 GeV. For VLQ’s in our model, we show that we can probe their masses up to 3.8 TeV, if we take only into account the high-luminosity phase of the LHC. Considering Run-III luminosities, we can also exclude VLQs for masses up to 3.4 TeV. We also show how the model with predicted VLL masses accommodates the muon anomalous magnetic moment.
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9.
  • Courbis, Anne-Lise, et al. (författare)
  • Electronic Clinical Decision Support System for allergic rhinitis management : MASK e-CDSS
  • 2018
  • Ingår i: Clinical and Experimental Allergy. - : WILEY. - 0954-7894 .- 1365-2222. ; 48:12, s. 1640-1653
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Allergic rhinitis (AR) management has changed in recent years following the switch from the concept of disease severity to the concept of disease control, publication of the AR clinical decision support system (CDSS) and development of mobile health (m-health) tools for patients (eg Allergy Diary). The Allergy Diary Companion app for healthcare providers is currently being developed and will be launched in 2018. It incorporates the AR CDSS to provide evidence-based treatment recommendations, linking all key stakeholders in AR management.Objective: To produce an electronic version of the AR CDSS (e-CDSS) for incorporation into the Allergy Diary Companion, to describe the app interfaces used to collect information necessary to inform the e-CDSS and to summarize some key features of the Allergy Diary Companion.Methods: The steps involved in producing the e-CDSS and incorporating it into the Allergy Diary Companion were (a) generation of treatment management scenarios; (b) expert consensus on treatment recommendations; (c) generation of electronic decisional algorithms to describe all AR CDSS scenarios; (d) digitization of these algorithms to form the e-CDSS; and (e) embedding the e-CDSS into the app to permit easy user e-CDSS interfacing.Results: Key experts in the AR field agreed on the AR CDSS approach to AR management and on specific treatment recommendations provided by Allergy Diary Companion. Based on this consensus, decision processes were developed and programmed into the Allergy Diary Companion using Titanium Appcelerator (JavaScript) for IOS tablets. To our knowledge, this is the first time the development of any m-health tool has been described in this transparent and detailed way, providing confidence, not only in the app, but also in the provided management recommendations.Conclusion: The Allergy Diary Companion for providers provides guideline and expert-endorsed AR management recommendations. [MASK paper No 32].
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10.
  • Dias, Pedro, et al. (författare)
  • Geophysical investigation of the down-dip extension of the Lombador massive sulphide deposit, Neves-Corvo, Portugal
  • 2021
  • Ingår i: International journal of earth sciences. - : Springer Nature. - 1437-3254 .- 1437-3262. ; 110:3, s. 911-922
  • Tidskriftsartikel (refereegranskat)abstract
    • The 150 Mt Lombador massive sulphide deposit is one of the seven known deposits of the Neves-Corvo mine. The deposit dips approximately 30o-35o to the NE and is open down dip, with current exploitation reaching down at 1 km depth. To investigate the possible downwards continuation of the deposit, a 1D constrained inversion of time-domain electromagnetic (TEM) ground loop data was conducted, followed by 3D electromagnetic (EM) forward modeling and a constrained 3D gravimetric inversion over the same area. To perform the EM and gravity modeling/inversion, a 3D geologic model was built using a density database comprising of approximately 300 drill-holes, and an electrical conductivity database with measurements from resistivity surveys and 1D inversion of the TEM data. The EM modeling shows that the Neves Formation shales are a regional conductive layer extending down to approximately 1.6 km depth in the Lombador area. This layer, often topped by massive sulphides, has an average density of 2.83 g/cm(3), whereas stockwork and massive sulphide reach on average 3.1 g/cm(3) and 4.5 g/cm(3), respectively. The 3D constrained gravity inversion results do not support the hypothesis of the presence of massive sulphides located in the down-dip direction of the Lombador deposit in the immediate vicinity of the known deposit. The lack of spatial resolution of the gravity grid, the study area limited size and the lack of information from within the basement suggest further studies are required to confirm the presence and amount of stockwork mineralization down-dip the Lombador deposit inside the Neves-Formation or the Phyllite-Quartzite basement.
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