Showing papers by "University of the Aegean published in 2021"

Disruptions and resilience in global container shipping and ports: the COVID-19 pandemic versus the 2008–2009 financial crisis

Abstract: Economic shocks test the resilience and adaptability of the shipping industry and container ports. Each crisis triggers different ramifications in the container market. This paper investigates the temporal and spatial sequences of the supply and demand shocks of COVID-19 on container ports and the container shipping industry by comparing these events to the 2008–2009 financial crisis. Using operational and financial data from primary and secondary sources, we analyze short-term impacts and their differences, the reasons for these variations, and the evolution in the adaptive capacity and resilience of ports, terminal operators, and carriers. The analysis revolves around several inter-related domains: impacts on global supply chains; impacts on operational aspects, market structure, and strategic behavior of shipping lines and terminal operators; impacts on port activity levels in terms of vessel calls and container volumes handled; and network impacts in terms of changes in aspects of container port connectivity. The changes observed and the strategic behavior of the market players involved reveal that further adaptation mechanisms, such as slow steaming, economies of scale, and capacity management, have been applied differently between the financial crisis and COVID-19, resulting in different outcomes. For an external shock such as COVID-19, impacts are the outcome of how ports and the shipping industry fit within complex supply chains and the cargo composition handled by ports.

Jet energy scale and resolution measured in proton-proton collisions at s =13 TeV with the ATLAS detector

Abstract: Jet energy scale and resolution measurements with their associated uncertainties are reported for jets using 36-81 fb$^{-1}$ of proton-proton collision data with a centre-of-mass energy of $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC. Jets are reconstructed using two different input types: topo-clusters formed from energy deposits in calorimeter cells, as well as an algorithmic combination of charged-particle tracks with those topo-clusters, referred to as the ATLAS particle-flow reconstruction method. The anti-$k_t$ jet algorithm with radius parameter $R=0.4$ is the primary jet definition used for both jet types. Jets are initially calibrated using a sequence of simulation-based corrections. Next, several $\textit{in situ}$ techniques are employed to correct for differences between data and simulation and to measure the resolution of jets. The systematic uncertainties in the jet energy scale for central jets ($|\eta| 2.5$ TeV). The relative jet energy resolution is measured and ranges from ($24 \pm 1.5$)% at 20 GeV to ($6 \pm 0.5$)% at 300 GeV.

Floating macrolitter leaked from Europe into the ocean

Abstract: Riverine systems act as converging pathways for discarded litter within drainage basins, becoming key elements in gauging the transfer of mismanaged waste into the ocean. However, riverine litter data are scarce and biased towards microplastics, generally lacking information about larger items. Based on the first ever database of riverine floating macrolitter across Europe, we have estimated that between 307 and 925 million litter items are released annually from Europe into the ocean. The plastic fraction represented 82% of the observed litter, mainly fragments and single-use items (that is, bottles, packaging and bags). Our modelled estimates show that a major portion of the total litter loading is routed through small-sized drainage basins (<100 km2), indicating the relevance of small rivers, streams and coastal run-off. Moreover, the major contribution of high-income countries to the macrolitter inputs suggests that reducing ocean pollution cannot be achieved only by improving waste management, but also requires changing consumption habits and behaviour to curb waste generation at source. The inability of countries with well-developed recovery systems to control the leakage of waste into the environment further supports the need to regulate the production and use of plastic on a global scale. Riverine systems help transfer mismanaged waste into the ocean, but riverine litter data are scarce. Using a database of riverine floating macrolitter across Europe, this study estimates that 307–925 million litter items—82% of which is plastic—are transferred annually from Europe into the ocean.

Muon reconstruction and identification efficiency in ATLAS using the full Run 2 pp collision data set at √ s = 13 TeV

Abstract: This article documents the muon reconstruction and identification efficiency obtained by the ATLAS experiment for 139 $$\hbox {fb}^{-1}$$ fb - 1 of pp collision data at $$\sqrt{s}=13$$ s = 13 TeV collected between 2015 and 2018 during Run 2 of the LHC. The increased instantaneous luminosity delivered by the LHC over this period required a reoptimisation of the criteria for the identification of prompt muons. Improved and newly developed algorithms were deployed to preserve high muon identification efficiency with a low misidentification rate and good momentum resolution. The availability of large samples of $$Z\rightarrow \mu \mu $$ Z → μ μ and $$J/\psi \rightarrow \mu \mu $$ J / ψ → μ μ decays, and the minimisation of systematic uncertainties, allows the efficiencies of criteria for muon identification, primary vertex association, and isolation to be measured with an accuracy at the per-mille level in the bulk of the phase space, and up to the percent level in complex kinematic configurations. Excellent performance is achieved over a range of transverse momenta from 3 GeV to several hundred GeV, and across the full muon detector acceptance of $$|\eta |<2.7$$ | η | < 2.7 .

Nature inspired optimization algorithms or simply variations of metaheuristics

Abstract: In the last decade, we observe an increasing number of nature-inspired optimization algorithms, with authors often claiming their novelty and their capabilities of acting as powerful optimization techniques. However, a considerable number of these algorithms do not seem to draw inspiration from nature or to incorporate successful tactics, laws, or practices existing in natural systems, while also some of them have never been applied in any optimization field, since their first appearance in literature. This paper presents some interesting findings that have emerged after the extensive study of most of the existing nature-inspired algorithms. The need for irrationally introducing new nature inspired intelligent (NII) algorithms in literature is also questioned and possible drawbacks of NII algorithms met in literature are discussed. In addition, guidelines for the development of new nature-inspired algorithms are proposed, in an attempt to limit the misleading appearance of variation of metaheuristics as nature inspired optimization algorithms.

COVID-19 impact on global maritime mobility.

Abstract: To prevent the outbreak of the Coronavirus disease (COVID-19), many countries around the world went into lockdown and imposed unprecedented containment measures. These restrictions progressively produced changes to social behavior and global mobility patterns, evidently disrupting social and economic activities. Here, using maritime traffic data collected via a global network of Automatic Identification System (AIS) receivers, we analyze the effects that the COVID-19 pandemic and containment measures had on the shipping industry, which accounts alone for more than 80% of the world trade. We rely on multiple data-driven maritime mobility indexes to quantitatively assess ship mobility in a given unit of time. The mobility analysis here presented has a worldwide extent and is based on the computation of: Cumulative Navigated Miles (CNM) of all ships reporting their position and navigational status via AIS, number of active and idle ships, and fleet average speed. To highlight significant changes in shipping routes and operational patterns, we also compute and compare global and local vessel density maps. We compare 2020 mobility levels to those of previous years assuming that an unchanged growth rate would have been achieved, if not for COVID-19. Following the outbreak, we find an unprecedented drop in maritime mobility, across all categories of commercial shipping. With few exceptions, a generally reduced activity is observable from March to June 2020, when the most severe restrictions were in force. We quantify a variation of mobility between -5.62 and -13.77% for container ships, between +2.28 and -3.32% for dry bulk, between -0.22 and -9.27% for wet bulk, and between -19.57 and -42.77% for passenger traffic. The presented study is unprecedented for the uniqueness and completeness of the employed AIS dataset, which comprises a trillion AIS messages broadcast worldwide by 50,000 ships, a figure that closely parallels the documented size of the world merchant fleet.

8 Pillars X 8 Layers Model of Metacognition: Educational Strategies, Exercises &Trainings

Abstract: Metacognition is one of the foremost cardinal factors of achievement in the 21st century. Despite extensive research, there is still the need to build a unique model based on multidisciplinary research illuminating questions as regards the real nature of metacognition and the methods to develop metacognitive abilities. The current study presents a new layered model of metacognition based on well-established theories derived from cognitive science, psychology, physical and computer sciences, environmental and other sciences, even from philosophy. We describe in detail the cognitive and metacognitive processes involved in each layer, while particular emphasis is placed on the relation between the control processes as well as the special role of attention. According to our model, each layer of metacognition describes a higher-order control system which operates under the rule of a series of attention processes at an ever more refined, abstract, united and holistic level. The same applies to the cognitive processes and abilities such as attention, memory, perception, pattern recognition. At each higher level, they display more advanced attributes and functions responding to the necessity of creating more abstract mental representations and upper class motivations, thoughts and emotions. In addition, we recommend a number of strategies that support the metacognitive development at each level of the hierarchy. The multi-layered model of metacognition targets at enriching our understanding of how metacognition evolves and it has the potential to guide the development of more effective strategies in educational system.

Are litter, plastic and microplastic quantities increasing in the ocean?

Abstract: Whilst both plastic production and inputs at sea have increased since the 1950s, several modelling studies predict a further increase in the coming years in these respective quantities. We compiled scientific literature on trends in marine litter, consisting largely of plastic and microplastics in the ocean, understanding that monitoring programs or assessments for these aspects are varied, frequently focusing on limited components of the marine environment in different locations, and covering a wide spectrum of marine litter types, with limited standardization. Here we discuss how trends in the amounts of litter in the marine environment can be compared with the information provided by models. Increasing amounts of plastic are found in some regions, especially in remote areas, but many repeated surveys and monitoring efforts have failed to demonstrate any consistent real temporal trend. An observed steady state situation of plastic quantities in many marine compartments and the fate and transport of plastic in the marine environment remain areas for much needed further research.

Endocrine Disruptors Acting on Estrogen and Androgen Pathways Cause Reproductive Disorders through Multiple Mechanisms: A Review.

Abstract: Increasing contamination of the environment by toxic compounds such as endocrine disrupting chemicals (EDCs) is one of the major causes of reproductive defects in both sexes Estrogen/androgen pathways are of utmost importance in gonadal development, determination of secondary sex characteristics and gametogenesis Most of the EDCs mediate their action through respective receptors and/or downstream signaling The purpose of this review is to highlight the mechanism by which EDCs can trigger antagonistic or agonistic response, acting through estrogen/androgen receptors causing reproductive defects that lead to infertility In vitro, in vivo and in silico studies focusing on the impact of EDCs on estrogen/androgen pathways and related proteins published in the last decade were considered for the review PUBMED and PUBCHEM were used for literature search EDCs can bind to estrogen receptors (ERα and ERβ) and androgen receptors or activate alternative receptors such as G protein-coupled receptors (GPCR), GPR30, estrogen-related receptor (ERRγ) to activate estrogen signaling via downstream kinases Bisphenol A, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethylene, polychlorinated biphenyls and phthalates are major toxicants that interfere with the normal estrogen/androgen pathways leading to infertility in both sexes through many ways, including DNA damage in spermatozoids, altered methylation pattern, histone modifications and miRNA expression

Search for doubly and singly charged Higgs bosons decaying into vector bosons in multi-lepton final states with the ATLAS detector using proton-proton collisions at √s = 13 TeV

Abstract: A search for charged Higgs bosons decaying into W±W± or W±Z bosons is performed, involving experimental signatures with two leptons of the same charge, or three or four leptons with a variety of charge combinations, missing transverse momentum and jets. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb−1. The search is guided by a type-II seesaw model that extends the scalar sector of the Standard Model with a scalar triplet, leading to a phenomenology that includes doubly and singly charged Higgs bosons. Two scenarios are explored, corresponding to the pair production of doubly charged H±± bosons, or the associated production of a doubly charged H±± boson and a singly charged H± boson. No significant deviations from the Standard Model predictions are observed. H±± bosons are excluded at 95% confidence level up to 350 GeV and 230 GeV for the pair and associated production modes, respectively. [Figure not available: see fulltext.]

Search for squarks and gluinos in final states with jets and missing transverse momentum using 139 fb$^{-1}$ of $\sqrt{s}$ =13 TeV $pp$ collision data with the ATLAS detector

Abstract: A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded by the ATLAS experiment in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$. The results are interpreted in the context of various $R$-parity-conserving models where squarks and gluinos are produced in pairs or in association and a neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.30 TeV for a simplified model containing only a gluino and the lightest neutralino, assuming the latter is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.85 TeV are excluded if the lightest neutralino is massless. These limits extend substantially beyond the region of supersymmetric parameter space excluded previously by similar searches with the ATLAS detector.

Measurement of light-by-light scattering and search for axion-like particles with 2.2 nb$^{-1}$ of Pb+Pb data with the ATLAS detector

Abstract: This paper describes a measurement of light-by-light scattering based on Pb+Pb collision data recorded by the ATLAS experiment during Run 2 of the LHC. The study uses 2.2 nb$^{−1}$ of integrated luminosity collected in 2015 and 2018 at $ \sqrt{s_{\mathrm{NN}}} $ = 5.02 TeV. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy $ {E}_{\mathrm{T}}^{\gamma } $> 2.5 GeV, pseudorapidity |η$_{γ}$| 5 GeV, and with small diphoton transverse momentum and diphoton acoplanarity. The integrated and differential fiducial cross sections are measured and compared with theoretical predictions. The diphoton invariant mass distribution is used to set limits on the production of axion-like particles. This result provides the most stringent limits to date on axion-like particle production for masses in the range 6–100 GeV. Cross sections above 2 to 70 nb are excluded at the 95% CL in that mass interval.[graphic not available: see fulltext]

Sustainability Performance Analysis of Small and Medium Sized Enterprises: Criteria, Methods and Framework

Abstract: Small and medium sized enterprises (SMEs) play an important role in any economy as they contribute to GDP and employment. However, sustainability (right combination of economic, environmental and social) of SMEs is a major concern as they prioritize economic performance over environmental and social to remain competitive. Majority of prior researches on SMEs' sustainability either look at the impact of a few limited enablers (e.g. lean, green, innovation etc.) on sustainability performance or the effect of pressures and barriers on the sustainability performance. There is a clear gap of a holistic and robust framework for sustainability performance analysis in order to measure and improve sustainability performance. This research bridges this knowledge gap by addressing two research questions – what practice and performance criteria are being considered for sustainability performance analysis in a broad environmental, economic and social context, how are they related, and what methods are being used to derive the relationship between sustainability practices and performance. These research questions are addressed through a systematic literature review of 58 papers, published between 2005 and 2018 in leading journals. First, an objective content analysis is undertaken in order to identify sustainability practices and performance criteria along with their frequency of usage in prior research. Second, the correlation among the variables is studied. Third, the methods for analyzing the relationships of the criteria are identified. Finally, a framework for analysing correlation of SMEs’ sustainability practices and performance in order to measure and improve performance using statistical modeling approach is proposed.

Cruise and container shipping companies: a comparative analysis of sustainable development goals through environmental sustainability disclosure

Abstract: The shipping industry, due to the ships’ gigantism trend and the concentration of operations in specific regions, is considered the source of both positive and negative impacts for port-cities. The...

Cyber Threats to Industrial IoT: A Survey on Attacks and Countermeasures

Abstract: In today’s Industrial Internet of Things (IIoT) environment, where different systems interact with the physical world, the state proposed by the Industry 4.0 standards can lead to escalating vulnerabilities, especially when these systems receive data streams from multiple intermediaries, requiring multilevel security approaches, in addition to link encryption. At the same time taking into account the heterogeneity of the systems included in the IIoT ecosystem and the non-institutionalized interoperability in terms of hardware and software, serious issues arise as to how to secure these systems. In this framework, given that the protection of industrial equipment is a requirement inextricably linked to technological developments and the use of the IoT, it is important to identify the major vulnerabilities and the associated risks and threats and to suggest the most appropriate countermeasures. In this context, this study provides a description of the attacks against IIoT systems, as well as a thorough analysis of the solutions for these attacks, as they have been proposed in the most recent literature.

Trends in flow intermittence for European rivers

Abstract: Intermittent rivers are prevalent in many countries across Europe, but little is known about the temporal evolution of intermittence and its relationship with climate variability. Trend analysis of...

Behavioral finance and market efficiency in the time of the COVID-19 pandemic: does fear drive the market?

Abstract: In this study, we examine the efficiency of the US stock markets during the COVID-19 outbreak using a fundamental financial analysis approach, the constant growth model and a behavioral model inclu...

Thwarting All Logic Locking Attacks: Dishonest Oracle With Truly Random Logic Locking

Abstract: While logic locking is a promising defense to protect hardware designs, many attacks have been shown to undermine its security by retrieving the secret key. All the powerful attacks rely on a working chip, i.e., an oracle, and in particular, heavily use the test access. The proposed technique DisORC turns the oracle into a dishonest one whenever a potential attack is detected. DisORC works on the premise that structural testing of chips need not be performed with the correct functionality. We implement this capability by adding circuitry around a logic-locked design that reconfigures its functionality upon detecting access to scan chains. Any attempt to access scan chains disconnects the secret key from the circuit, and clears all of its traces, isolating and securing it. We also pair this defense with a truly random logic locking (TRLL) scheme that makes random decisions in inserting key gates and retaining signal polarities without relying on any logic synthesis technique to perform bubble pushing. Any netlist analysis-based attack, known or anticipated, will then learn nothing useful to infer the key values. The combined defense DisORC + TRLL thwarts oracle-based and netlist analysis-based attacks while delivering sufficient corruption levels at the outputs. We also show that the proposed defense is cost effective and can be integrated into the design flow easily. The proposed logic locking defense provides protection against untrusted foundry, testing facility, end users, and any combination of them colluding together.

Search for heavy resonances decaying into a pair of Z bosons in the ℓ+ℓ-ℓ′ +ℓ′ - and ℓ+ℓ-νν¯ final states using 139 fb - 1 of proton–proton collisions at √s=13 TeV with the ATLAS detector

Abstract: A search for heavy resonances decaying into a pair of Z bosons leading to $\ell ^+\ell ^-\ell '^+\ell '^-$ and $\ell ^+\ell ^- u {{\bar{ u }}}$ final states, where $\ell $ stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV collected from 2015 to 2018 that corresponds to the integrated luminosity of 139 $\mathrm {fb}^{-1}$ recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Different mass ranges spanning 200 GeV to 2000 GeV for the hypothetical resonances are considered, depending on the final state and model. In the absence of a significant observed excess, the results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, and the limits for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.

Virtual and Augmented Reality for Developing Emotional Intelligence Skills

Abstract: The development and the cultivation of emotional intelligence and of the skills it can offer to the individual are the main elements and pursuits of contemporary research. The enhancement of self-control, the reinforcement of self-criticism and self-awareness and the cultivation of the constant self-development are the most central objectives of all the people and of the scientists since they are the cornerstone for euphoria. The aim of the present study is the review and the critical reproduction of information and conclusions that have been extracted from the international bibliography regarding the issue in question. More specifically, there will be an effort to evaluate and present the significance of the activities of virtual reality and of augmented reality that contribute to the development of emotional intelligence skills. Along the same lines, there will be an important review of the articles that refer to the exploitation of such digital tools, to achieve the same results for the people suffering from autism as well. Besides, the care for all the members of the society with no exceptions, and certainly of those members that suffer from mental retardation, should be of upmost importance. The present article focuses on the role that those tools play for the amplification of the skills in the sphere of emotional intelligence not only as far as the duration of the research is concerned.

Empirical Evaluation of Attacks Against IEEE 802.11 Enterprise Networks: The AWID3 Dataset

Abstract: This work serves two key objectives. First, it markedly supplements and extends the well-known AWID corpus by capturing and studying traces of a wide variety of attacks hurled in the IEEE 802.1X Extensible Authentication Protocol (EAP) environment. Second, given that all the 802.11-oriented attacks have been carried out when the defenses introduced by Protected Management Frames (PMF) were operative, it offers the first to our knowledge full-fledged empirical study regarding the robustness of the IEEE 802.11w amendment, which is mandatory for WPA3 certified devices. Under both the aforementioned settings, the dataset, and study at hand are novel and are anticipated to be of significant aid towards designing and evaluating intrusion detection systems. Moreover, in an effort to deliver a well-rounded dataset of greater lifespan, and under the prism of an attacker escalating their assault from the wireless MAC layer to higher ones, we have additionally included several assaults that are common to IEEE 802.3 networks. Since the corpus is publicly offered in the form of raw cleartext pcap files, future research can straightforwardly exploit any subset of features, depending on the particular application scenario.

Cyber Threats to Industrial IoT: A Survey on Attacks and Countermeasures

Abstract: In today’s Industrial Internet of Things (IIoT) environment, where different systems interact with the physical world, the state proposed by the Industry 4.0 standards can lead to escalating vulnerabilities, especially when these systems receive data streams from multiple intermediaries, requiring multilevel security approaches, in addition to link encryption. At the same time taking into account the heterogeneity of the systems included in the IIoT ecosystem and the non-institutionalized interoperability in terms of hardware and software, serious issues arise as to how to secure these systems. In this framework, given that the protection of industrial equipment is a requirement inextricably linked to technological developments and the use of the IoT, it is important to identify the major vulnerabilities and the associated risks and threats and to suggest the most appropriate countermeasures. In this context, this study provides a description of the attacks against IIoT systems, as well as a thorough analysis of the solutions for these attacks, as they have been proposed in the most recent literature.

Application of simulation modeling for wildfire exposure and transmission assessment in Sardinia, Italy

Abstract: The development of comprehensive fire management and risk assessment strategies is of prominent concern in Southern Europe, due to the expanding scale of wildfire risk. In this work, we applied simulation modeling to analyze fine-scale (100-m resolution) wildfire exposure and risk transmission in the 24,000 km2 island of Sardinia (Italy). Sardinia contains a variety of ecological, cultural, anthropic and touristic resources that each summer are threatened by wildfires, and represents well the Mediterranean Basin environments and conditions. Wildfire simulations based on the minimum travel time algorithm were used to characterize wildfire exposure and risk transmission in terms of annual burn probability, flame length, structures exposed and type and amount of transmission. We focused on the historical conditions associated with large (>50 ha) and very large (>200 ha) wildfires that occurred in Sardinia in the period 1998–2016, and combined outputs from wildfire simulation modeling with land uses, building footprint locations, weather, and historical ignition data. The outputs were summarized for weather zones, main wind scenarios and land uses. Our study characterized spatial variations in wildfire spread, exposure and risk transmission among and within weather zones and the main winds associated with large events. This work provides a novel quantitative approach to inform wildfire risk management and planning in Mediterranean areas. The proposed methodology can serve as reference for wildfire risk assessment and can be replicated elsewhere. Findings can be used to better understand the spatial dynamics and patterns of wildfire risk and evaluate expected wildfire behavior or transmission potential in Sardinia and neighboring regions.

Who Is Willing to Share Their AV? Insights about Gender Differences among Seven Countries

Abstract: The introduction of shared autonomous vehicles into the transport system is suggested to bring significant impacts on traffic conditions, road safety and emissions, as well as overall reshaping travel behaviour. Compared with a private autonomous vehicle, a shared automated vehicle (SAV) is associated with different willingness-to-adopt and willingness-to-pay characteristics. An important aspect of future SAV adoption is the presence of other passengers in the SAV—often people unknown to the cotravellers. This study presents a cross-country exploration of user preferences and WTP calculations regarding mode choice between a private non-autonomous vehicle, and private and shared autonomous vehicles. To explore user preferences, the study launched a survey in seven European countries, including a stated-preference experiment of user choices. To model and quantify the effect of travel mode attributes and socio-demographic characteristics, the study employs a mixed logit model. The model results were the basis for calculating willingness-to-pay values for all countries and travel modes, and provide insight into the significant heterogeneous, gender-wise effect of cotravellers in the choice to use an SAV. The study results highlight the importance of analysis of the effect of SAV attributes and shared-ride conditions on the future acceptance and adoption rates of such services.

Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at √{s } = 13 TeV with the ATLAS detector

Abstract: A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton is presented The search is based on a dataset of pp collisions at s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1 Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons In addition, two or more jets, at least one of which must be identified as containing b-hadrons, are required Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds The signal-rich event categories require at least one hadronically decaying τ-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 143 TeV while, for a branching fraction of 50% into tτ, the lower mass limit is 122 TeV [Figure not available: see fulltext]

Pansharpening PRISMA Data for Marine Plastic Litter Detection Using Plastic Indexes

Abstract: Hyperspectral PRISMA images are new and have not yet been evaluated for their ability to detect marine plastic litter. The hyperspectral PRISMA images have a fine spectral resolution, however, their spatial resolution is not high enough to enable the discrimination of small plastic objects in the ocean. Pansharpening with the panchromatic data enhances their spatial resolution and makes their detection capabilities a technological challenge. This study exploits, for the first time, the potential of using satellite hyperspectral data in detecting small-sized marine plastic litter. Controlled experiments with plastic targets of various sizes constructed from several materials have been conducted. The required pre-processing steps have been defined and 13 pansharpening methods have been applied and evaluated for their ability to spectrally discriminate plastics from water. Among them, the PCA-based substitution efficiently separates plastic spectra from water without producing duplicate edges, or pixelation. Plastic targets with size equivalent to 8% of the original hyperspectral image pixel coverage are easily detected. The same targets can also be observed in the panchromatic image, however, they cannot be detected solely by the panchromatic information as they are confused with other appearances. Exploiting spectra derived from the pan-sharpened hyperspectral images, an index combining methodology has been developed, which enables the detection of plastic objects. Although spectra of plastic materials present similarities with water spectra, some spectral characteristics can be utilized for producing marine plastic litter indexes. Based on these indexes, the index combining methodology has successfully detected the plastic targets and differentiated them from other materials.