Month: February 2024

Ballast water management systems protect the Great Lakes from secondary spread of non-indigenous species

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Abstract

Approximately 65% of established non-indigenous species (NIS) identified in the Great Lakes–Saint Lawrence River basin (GLSLR) since 1959 were introduced by ballast water discharges from transoceanic vessels. While the rate of new detections has sharply declined, NIS already present may spread within the system—including upstream—through secondary invasions by domestic ballast water transferred mainly by ‘laker’ vessels. Canada has mandated that all vessels loading or unloading in waters under Canadian jurisdiction in the GLSLR will need to use ballast water management systems (BWMS) by 2030. Here we used simulations informed by empirical data to investigate the expected efficacy of BWMS in reducing zooplankton and phytoplankton introductions on a per-trip basis, and the corresponding probabilities of survival and establishment related to ballast water discharges within the GLSLR. We investigated three ballast water scenarios: no treatment, full treatment, and treatment by a partially-functioning BWMS (owing to malfunctions or challenging water quality). Fully-functioning BWMS reduced community pressure by > 99% and corresponding establishment risk of NIS by 38% and 66% relative to untreated ballast discharges for zooplankton and phytoplankton, respectively. Partial treatment (modelled as a 95% reduction in organism concentrations) resulted in 10–20% reduction in per-trip probability of NIS establishment; results indicate that trips with BWMS inoperability caused by highly turbid uptake conditions may be less risky than trips with BWMS inoperability due to plankton blooms. The implementation of BWMS is expected to reduce risk of secondary spread within the GLSLR system by ballast water, even if the BWMS are subject to periodic malfunction.

Addressing the gap: advancements in flow forecasting systems for small mountainous catchments

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Abstract

A comparison of methodologies was carried out to develop an operational flow forecasting system for a mountainous catchment. The case studied was the Boi River, which is located in a small mountainous catchment in southern Brazil. This catchment is part of a conservation unit well known for the beautiful landscapes and ecotourism activities carried out in that place. Among the activities, the Boi River trail can be highlighted, which is carried out following the riverbed. For this reason, the development of an alert system for this basin can help in determining the trail's closure in situations where the water flow is strong and could present risks to tourists’ safety. Thereby, the aim of this study was to assess two distinct scenarios for the development of the forecasting system. First, the flow forecasts were performed using SOPREVA and considered a horizon of 1 day (short-term forecasts). The second scenario considered medium-term forecasts (1–10 days horizon) and utilized the HEC-RTS as a basis for developing the forecast system. In both cases, the forecasts were based on the ensemble precipitation estimates of GEFS. The obtained results showed that the actual alarm rates were 0.77 and 0.86 for SOPREVA and HEC-RTS, respectively, when considering a horizon of one day in advance. The evaluation of the medium-term forecasts presented good results of this system for horizons up to 3 days in advance. Finally, the results of both considered scenarios showed that the systems could be used as a basis for management of the Boi River trail.

Lifetime maximization of wireless sensor networks while ensuring intruder detection

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Abstract

Wireless sensor networks (WSN) have a wide variety of application areas and one of these areas is border crossing security. Unauthorized crossing of border areas, unauthorized arms and drug trafficking can be avoided at a lower cost and easier than conventional methods by monitoring the borders with the help of a WSN. In this study, we offer a mathematical model that guarantees the detection of possible intruders by scheduling the activities of the sensors whatever the route the intruder follows throughout the border zone or whatever the time the intruder enters to the route. To achieve the highest possible WSN management efficiency, we integrate coverage, routing, data routing, and sensor scheduling WSN design issues into the mathematical model. We first demonstrate the effectiveness of scheduling the sensors by the help of the offered mathematical model by comparing it against a random activity schedule of the sensors with respect to network lifetime and intruder detection ratio performance measures. We also develop a Lagrangean heuristic strategy to solve realistic sized instances of the proposed problem. We produce several random border zone instances with varying sizes and test the proposed solution strategy to illustrate the effectiveness of the offered solution strategy by comparing its performance against the performance of a commercial mixed-integer linear programming (MILP) solver.

Groundwater recharge processes in the Lake Chad Basin based on isotopic and chemical data

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Abstract

The Lake Chad Basin is Africa’s largest endorheic basin. Because water supply for the rural population and most of the urban population depends on groundwater, assessment of groundwater recharge is crucial. Recharge sources for the upper Quaternary aquifer are precipitation, rivers, and swamps. Using water chemistry, and environmental (18O, 2H, 3H) and carbon (14C) isotopes, recharge processes can be assessed and groundwater ages roughly estimated. For this purpose, more than 1,000 samples from groundwater, surface water and precipitation were analysed for hydrochemistry and environmental stable isotopes. Furthermore, 3H measurements and 14C values of dissolved inorganic carbon for groundwater from the northeastern part of the Basin are included in the evaluation. The environmental isotope distribution shows recent recharge from precipitation north of Lake Chad (Kanem Region), where very low 3H values indicate occurrence before the 1960s bomb peak. Focused recharge from fresh river water is typical for Salamat Region in south Chad and the Komadugu Yobe wetlands between Nigeria and Niger. Slightly high δ-values in water occur in the Waza Logone area between Chad and Cameroon. Groundwater along the Lake Chad shore and the Bahr el Ghazal corridor show high δ-values (δ18O –0.78 to 7.45‰, δ2H –13.6 to 30.8‰). Recharge is caused by surface water that undergoes evaporative processes before percolation. Groundwater ages of 600–4,150 years, estimated from 14C analyses combined with high SO4 concentrations, along the Bahr el Ghazal indicate that recharge was caused by residuals of the Mega Lake before it dried out completely.

Environment geometry alters subiculum boundary vector cell receptive fields in adulthood and early development

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Abstract

Boundaries to movement form a specific class of landmark information used for navigation: Boundary Vector Cells (BVCs) are neurons which encode an animal’s location as a vector displacement from boundaries. Here we characterise the prevalence and spatial tuning of subiculum BVCs in adult and developing male rats, and investigate the relationship between BVC spatial firing and boundary geometry. BVC directional tunings align with environment walls in squares, but are uniformly distributed in circles, demonstrating that environmental geometry alters BVC receptive fields. Inserted barriers uncover both excitatory and inhibitory components to BVC receptive fields, demonstrating that inhibitory inputs contribute to BVC field formation. During post-natal development, subiculum BVCs mature slowly, contrasting with the earlier maturation of boundary-responsive cells in upstream Entorhinal Cortex. However, Subiculum and Entorhinal BVC receptive fields are altered by boundary geometry as early as tested, suggesting this is an inherent feature of the hippocampal representation of space.

Territoriality and the Quest for a Unitary Copyright Title

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Abstract

After 30 years of harmonization at EU level, copyright and related rights remain decidedly territorial in scope. This is despite the continuous quest for an internal market and the profound impact on cross-border creation, dissemination and use of cultural content. This contribution recounts the outcome of research done on territoriality in the context of the ReCreating Europe project. It discusses why national territorial rights persist, what type of legal mechanisms the EU legislature employs to address the adverse effects of territoriality, and sketches a number of models for a unitary title based on Art. 118 TFEU which could be explored going forward.

Jetting bubbles observed by x-ray holography at a free-electron laser: internal structure and the effect of non-axisymmetric boundary conditions

Latest Results

Abstract

In this work, we study the jetting dynamics of individual cavitation bubbles using x-ray holographic imaging and high-speed optical shadowgraphy. The bubbles are induced by a focused infrared laser pulse in water near the surface of a flat, circular glass plate, and later probed with ultrashort x-ray pulses produced by an x-ray free-electron laser (XFEL). The holographic imaging can reveal essential information of the bubble interior that would otherwise not be accessible in the optical regime due to obscuration or diffraction. The influence of asymmetric boundary conditions on the jet’s characteristics is analysed for cases where the axial symmetry is perturbed and curved liquid filaments can form inside the cavity. The x-ray images demonstrate that when oblique jets impact the rigid boundary, they produce a non-axisymmetric splash which grows from a moving stagnation point. Additionally, the images reveal the formation of complex gas/liquid structures inside the jetting bubbles that are invisible to standard optical microscopy. The experimental results are analysed with the assistance of full three-dimensional numerical simulations of the Navier–Stokes equations in their compressible formulation, which allow a deeper understanding of the distinctive features observed in the x-ray holographic images. In particular, the effects of varying the dimensionless stand-off distances measured from the initial bubble location to the surface of the solid plate and also to its nearest edge are addressed using both experiments and simulations. A relation between the jet tilting angle and the dimensionless bubble position asymmetry is derived. The present study provides new insights into bubble jetting and demonstrates the potential of x-ray holography for future investigations in this field.

Navigating the myriad of corporate quality standards: a CSR and stakeholder perspective

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Abstract

Quality standards (QS) (e.g., ISO 9001) play an important role in assuring the quality of goods and services for organizational stakeholders on a global scale. Recent work has highlighted the role of QS in communicating corporate social responsibility (CSR) practices to a firm’s stakeholders making both the QS adoption decision and the timing of adoption of immense strategic importance to top managers. However, the types of QS and their intended and unintended beneficiaries vary widely, making it difficult for managers to choose QS that are in accord with their CSR goals. Further, current economic (cost/benefit) and institutionally-based theoretical approaches do not provide managers with adequate guidance in making strategic adoption decisions. Rapid developments in QS practices have also made it difficult for researchers to incorporate them into CSR theory. Drawing upon a literature review of QSs and stakeholder theory, this study presents a QS framework and taxonomy that integrates QS adoption timing and beneficiaries. The framework also presents four configurations of QS adopters and their associated beneficiary stakeholder groups, enabling both researchers and practitioners to more completely understand the complex nature of stakeholder pressures on organizations.

Analysis of brain and blood single-cell transcriptomics in acute and subacute phases after experimental stroke

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Abstract

Cerebral ischemia triggers a powerful inflammatory reaction involving peripheral leukocytes and brain resident cells that contribute to both tissue injury and repair. However, their dynamics and diversity remain poorly understood. To address these limitations, we performed a single-cell transcriptomic study of brain and blood cells 2 or 14 days after ischemic stroke in mice. We observed a strong divergence of post-ischemic microglia, monocyte-derived macrophages and neutrophils over time, while endothelial cells and brain-associated macrophages showed altered transcriptomic signatures at 2 days poststroke. Trajectory inference predicted the in situ trans-differentiation of macrophages from blood monocytes into day 2 and day 14 phenotypes, while neutrophils were projected to be continuously de novo recruited from the blood. Brain single-cell transcriptomes from both female and male aged mice were similar to that of young male mice, but aged and young brains differed in their immune cell composition. Although blood leukocyte analysis also revealed altered transcriptomes after stroke, brain-infiltrating leukocytes displayed higher transcriptomic divergence than their circulating counterparts, indicating that phenotypic diversification occurs within the brain in the early and recovery phases of ischemic stroke. A portal (https://anratherlab.shinyapps.io/strokevis/) is provided to allow user-friendly access to our data.

Twitter’s pulse on hydrogen energy in 280 characters: a data perspective

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Abstract

Uncovering the public discourse on hydrogen energy is essential for understanding public behaviour and the evolving nature of conversations over time and across different regions. This paper presents a comprehensive analysis of a large multilingual dataset pertaining to hydrogen energy collected from Twitter spanning a decade (2013–2022) using selected keywords. The analysis aims to explore various aspects, including the temporal and spatial dimensions of the discourse, factors influencing Twitter engagement, user engagement patterns, and the interpretation of conversations through hashtags and ngrams. By delving into these aspects, this study offers valuable insights into the dynamics of public discourse surrounding hydrogen energy and the perceptions of social media users.