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ECO-HYDRO-MORPHODYNAMICS OF RIVER DELTAS: HOW VEGETATION SHAPES WATER TRANSPORT TIMESCALES, CHANNEL NETWORKS, AND SYSTEM CONNECTIVITY
No full textRiver deltas are among the Earth\u27s most dynamic ecosystems, supporting over 500 million people globally while providing essential ecosystem services; yet they face unprecedented challenges from climate change, sea-level rise, and anthropogenic modifications. Vegetation acts as an ecosystem engineer, actively modifying hydrodynamic processes and morphological evolution. However, quantitative relationships between seasonal vegetation dynamics, water transport timescales, and system-scale hydrological connectivity remain poorly understood. This dissertation quantifies the influence of vegetation on water movement and age across seasonal to decadal timescales in river deltas. This research integrates high-resolution hydromorphodynamic modeling with dynamic vegetation simulation to investigate vegetation-hydrodynamic interactions from local to system-wide scales in river deltas. We find that vegetation creates multi-scale effects on transport processes, significantly influencing local-scale water age distributions within deltaic floodplains, while having limited effects on the network scale. Vegetation presence controls volumetric flow toward deltaic floodplains, with the spatial distribution of vegetation having a larger impact than stem density. Coupled ecomorphodynamic modeling reveals that seasonal vegetation dynamics facilitate the formation of larger islands while stabilizing channels and improving network geometric efficiency. Simulations that include biogeomorphic feedback result in more elongated morphologies, whereas non-vegetated deltas expand laterally. Seasonal vegetation dynamics emerge as a key influence on channel network formation and dynamics. Water age distributions are spatially partitioned: channels display unimodal distributions that are strongly correlated with sedimentation, while islands exhibit multimodal patterns with weakened sediment-age correlations. System-scale hydrologic connectivity exhibits regime shifts, with discharge being the main driver in non-vegetated systems compared to vegetation in vegetated systems. Key findings of this dissertation include: vegetation creates distinct local versus network scale transport effects; seasonal vegetation dynamics promote efficient network organization through biogeomorphic feedback, thereby enhancing system resilience; vegetation induces hydrological connectivity regime shifts that alter system responses to hydrological forcing; and seasonal dynamics are critical for predicting long-term evolution. This research advances understanding of deltaic ecohydromorphodynamics while providing practical insights for coastal management and restoration strategies. Findings demonstrate that coordinating sediment delivery with vegetation cycles can enhance the efficiency of coastal restoration strategies, such as sediment diversions, where network geometric efficiency can serve as a design criterion
Unraveling the Lullabies of Learning: Exploring the Role of Individual Components of Infant-Directed Speech in Language Learning
No full textChildren learn language more effectively from infant-directed speech (IDS) than adult-directed speech (ADS). Three experiments were run (a pilot and two full experiments) testing the effects of pitch and pitch variability on segmenting a target word out of the speech stream and then associating it to an object. Visual prosody via eyebrow movements and lip contours were added as additional cues after the Pilot Study. Additional factors included after the Pilot Study were shortened sentences from 10 syllables each to seven syllables each, shortened target words from three syllables to two syllables, consistent syllable onset of target words, and two different carrier phrases (utterances surrounding the target word) for each item rather than one carrier phrase presented twice. Target words were placed in the middle of the sentence (utterance-medial) in the Pilot Study and Experiment 2; target words were place at the end of the sentence (utterance-final) in Experiment 1. The results of the Pilot Study supported our hypothesis that contrasting the mean pitch and pitch variability of the target word from the carrier phrase benefits initial association task performance. The results of Experiment 1 did not support our hypothesis that contrasting the mean pitch and pitch variability of the target word from the carrier phrase facilitates segmentation and association, but the findings did indicate that utterance-final placement of target words yields successful segmentation and association performance, regardless of whether visual prosody was present. The results of Experiment 2 supported our hypothesis that the contrast between the carrier phrase and the target word facilitates initial and delay association task performance, especially when visual prosody was present, however regular IDS promoted successful association task performance regardless of whether visual cues were present or absent. Overall, we concluded that manipulating specific factors of speech may not be lucrative in the context of naturalistic speech and that the benefit of IDS exists as a result of the combination of its exaggerated acoustic and visual factors
AUTOMATED BIM-BASED RULE CHECKING OF FLOOD RESILIENCE REGULATIONS FOR SINGLE FAMILY HOUSES
No full textFlooding remains the most recurrent and economically disruptive natural hazard in Louisiana, where resilience efforts are often hindered by fragmented regulations, inconsistent code enforcement, and limited technical capacity. This dissertation develops and validates an automated Building Information Modeling (BIM)–based rule-checking framework designed to evaluate single-family residential buildings for flood-resilience compliance with the International Residential Code (IRC, 2021), ASCE 24-14, and FEMA Technical Bulletins.
The system converts narrative regulatory provisions into machine-interpretable logic using First-Order Logic (FOL), operationalized through a JSON-based metadata schema and executed on Industry Foundation Classes (IFC) models via IfcOpenShell and Python. A total of 162 synthetic housing scenarios representing six foundation types and five flood-zone classifications were analyzed to assess system performance. Compliance outcomes across four regulatory categories—elevation and freeboard, flood openings, breakaway walls, and free-of-obstruction—were synthesized into a Regulatory Compliance Score (RCS). The RCS quantifies the degree of conformity between building designs and flood-resilient construction requirements, offering a standardized indicator for evaluating and comparing structural compliance.
This research introduces the RCS as a novel resilience indicator, enabling the automated evaluation of design compliance and providing a foundation for integrating rule-based validation into flood-resilient design practice. The proposed framework establishes a replicable, transparent, and data-driven model for regulatory automation, supporting decision-making in flood mitigation and housing policy.
The framework advances both theory and practice by uniting regulatory automation with resilience analytics, offering a scalable model for adaptive governance. It provides a replicable approach for digital code enforcement, enabling transparent, data-driven decision-making in hazard mitigation. The research concludes that the integration of logic-based automation and socio-environmental data can fundamentally transform resilience assessment from a reactive to a proactive process, positioning Louisiana as a leader in evidence-based flood governance
Non-Reciprocal Coupling of Minimal Active Colloids under Confinement: Rotating Ferromagnetic Janus Particles near Boundaries
No full textActive colloids are microscopic particles that convert energy at the single-particle level into sustained motion and dynamically evolving assemblies. Their ability to transform continuous energy input into controlled motion opens new frontiers in microrobotics, adaptive materials, and targeted transport. Yet, achieving efficient propulsion at the microscale remains fundamentally challenging because viscous forces dominate while inertia becomes negligible. Unlike macroscopic systems that sustain propulsion through momentum, active colloids must harness non-reciprocal interactions with the surrounding fluid to generate persistent, time-irreversible motion. Studying minimal active systems—the simplest realizations that still capture the essential physics—provides a powerful route to uncover the non-equilibrium principles governing collective behavior and to inform the design of intelligent active materials.
First, we investigate the boundary-driven dynamics of an active ferromagnetic Janus particle near a stationary substrate when actuated by an oscillating magnetic field. By systematically varying the particle–boundary separation, we identify distinct regimes of motion—rolling at the boundary, pure rotation far from the wall, and, at intermediate elevations, tumbling and trochoidal trajectories that depend on the field frequency. These dynamic states arise from the interplay between magnetic and gravitational torques and hydrodynamic resistance. Particle Image Velocimetry reveals elevation-dependent flow fields and fluctuating vortical structures, demonstrating how boundaries reshape particle–medium coupling and sustain non-reciprocal motion even far from contact.
Second, we explore the organizing principles of pairwise interactions between active Janus particles in confinement. Within a specific range of interparticle distances and orientations, the particles exhibit predator–prey–like chases, where one persistently follows the other without capture. These interactions amplify the system’s non-reciprocity through coupled hydrodynamic and magnetic fields, reducing drag and enhancing translational speeds relative to isolated motion. The identification of an effective interaction region and velocity–direction correlations provides a quantitative description of when such collective pursuit emerges.
Together, these studies establish how boundaries act as decisive levers of non-reciprocal interaction, linking microscopic asymmetries to macroscopic organization. The insights developed here lay the foundation for designing next-generation microrobots and reconfigurable soft materials capable of navigating and adapting within complex, confined environments
Recovery of the X-ray polarisation of Swift J1727.8-1613 after the soft-to-hard spectral transition (Corrigendum) (Astronomy and Astrophysics (2024) 686 (L12) DOI: 10.1051/0004-6361/202450566)
No full text(Figure presented) In Fig. 4, the X-ray hardness value for observation 8 was plotted using a count-based ratio instead of the energy-flux-based ratio used for other points in the figure. The correction of the position of this point in Fig. 4 does not affect any other figures, results, or conclusions in the paper
X-Ray Polarization of the High-synchrotron-peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-Ray Flux States
No full textWe report the Imaging X-ray Polarimetry Explorer (IXPE) polarimetric and simultaneous multiwavelength observations of the high-energy-peaked BL Lacertae object (HBL) 1ES 1959+650, performed in 2022 October and 2023 August. In 2022 October, IXPE measured an average polarization degree ΠX = 9.4% ± 1.6% and an electric-vector position angle ψX = 53° ± 5°. The polarized X-ray emission can be decomposed into a constant component, plus a rotating component, with the rotation velocity ωEVPA = (−117 ± 12) deg day−1. In 2023 August, during a period of pronounced activity of the source, IXPE measured an average ΠX = 12.4% ± 0.7% and ψX = 20° ± 2°, with evidence (∼0.4% chance probability) for a rapidly rotating component with ωEVPA = 1864 ± 34 deg day−1. These findings suggest the presence of a helical magnetic field in the jet of 1ES 1959+650 or stochastic processes governing the field in turbulent plasma. Our multiwavelength campaigns from radio to X-ray reveal variability in both polarization and flux from optical to X-rays. We interpret the results in terms of a relatively slowly varying component dominating the radio and optical emission, while rapidly variable polarized components dominate the X-ray and provide minor contribution at optical wavelengths. The radio and optical data indicate that on parsec scales the magnetic field is primarily orthogonal to the jet direction. On the contrary, X-ray measurements show a magnetic field almost aligned with the parsec jet direction. Confronting with other IXPE observations, we guess that the magnetic field of HBLs on subparsec scale should be rather unstable, often changing its direction with respect to the Very Long Baseline Array jet
GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays
No full textWe present a complete analysis of Fermi Large Area Telescope (LAT) data of GRB 221009A, the brightest gamma-ray burst (GRB) ever detected. The burst emission above 30 MeV detected by the LAT preceded, by 1 s, the low-energy (\u3c 10 MeV) pulse that triggered the Fermi Gamma-Ray Burst Monitor (GBM), as has been observed in other GRBs. The prompt phase of GRB 221009A lasted a few hundred seconds. It was so bright that we identify a bad time interval of 64 s caused by the extremely high flux of hard X-rays and soft gamma rays, during which the event reconstruction efficiency was poor and the dead time fraction quite high. The late-time emission decayed as a power law, but the extrapolation of the late-time emission during the first 450 s suggests that the afterglow started during the prompt emission. We also found that high-energy events observed by the LAT are incompatible with synchrotron origin, and, during the prompt emission, are more likely related to an extra component identified as synchrotron self-Compton (SSC). A remarkable 400 GeV photon, detected by the LAT 33 ks after the GBM trigger and directionally consistent with the location of GRB 221009A, is hard to explain as a product of SSC or TeV electromagnetic cascades, and the process responsible for its origin is uncertain. Because of its proximity and energetic nature, GRB 221009A is an extremely rare event
Magnetotransport properties in epitaxial films of metallic delafossite PdCoO2: Effects of thickness and width variations in Hall bar devices
No full textWe report on a combined structural and magnetotransport study of Hall bar devices of various lateral dimensions patterned side-by-side on epitaxial PdCoO2 thin films. We study the effects of both the thickness of the PdCoO2 film and the width of the channel on the electronic transport and the magnetoresistance properties of the Hall bar devices. All the films with thicknesses down to 4.88 nm are epitaxially oriented, phase-pure, and exhibit metallic behavior. At room temperature, resistivity values as low as 6.85 and 8.17μωcm are achieved in Hall bar devices with channel width W=2.5μm and W=10μm, respectively. For the 4.88 nm thick sample, we find that while the density of the conduction electrons is comparable in both channels, the electrons move about twice as fast in the narrower channel. At low temperatures, for Hall bar devices of channel width 2.5μm fabricated on epitaxial films of thicknesses 4.88 and 5.21 nm, the electron mobilities of ≈65 and 40cm2V-1s-1, respectively, are extracted. For thin-film Hall bar devices of width 10μm fabricated on the same 4.88 and 5.21 nm thick samples, the mobility values of ≈32 and 18cm2V-1s-1 are obtained. The magnetoresistance characteristics of these PdCoO2 films are observed to be temperature- dependent and exhibit a dependency with the orientation of the applied magnetic field. When the applied field is oriented 90° away from the crystal c-axis, a persistent negative MR at all temperatures is observed. However when the field is parallel to the c-axis, the negative magnetoresistance is suppressed at temperatures above 150 K
ENVIS: A USER-CENTERED WEB-BASED TOOL FOR INTERACTIVE VISUALIZATION OF ENVIRONMENTAL GEOSPATIAL DATA
No full textData visualization is an essential part of analyzing environmental geospatial data. Despite having the availability of large environmental datasets, there remains a lack of easily accessible, user-friendly, and interactive visualization tools in this field. Therefore, this study aims to develop a user-friendly and easily available web-based visualization tool. Before developing the tool, we conducted a survey of researchers at the LSU Coastal Studies Institute to collect their opinions on currently available visualization tools. In the survey, 55% of participants responded between somewhat satisfied to dissatisfied with their current visualization tools. Most of the participants mentioned two major limitations of existing visualization tools. These limitations are overly complex interfaces of the existing visualization tools and the need for basic programming knowledge to use these tools. To address these issues, we have developed EnVis, an easily accessible, interactive, and dynamic web-based tool that provides effective data analysis and visualizations for large environmental datasets. EnVis combines a React-based frontend and a Flask backend, which delivers user-friendly and responsive map-based data visualizations. The key feature of this web tool is that users can upload their own environmental datasets for quick visualization. On the Leaflet map, users can hover over and click on each datapoint to examine individual grid-cell values in detail without writing a single line of code. Researchers can also assess their large datasets and make informed decisions whether they want to invest their time in the datasets for further analysis. Additionally, EnVis provides daily visualization for two widely used environmental variables, such as sea surface temperature (SST) and atmospheric dust. These daily visualizations help researchers to explore seasonal patterns and trends in SST and atmospheric dust more easily and effectively. After developing EnVis, we conducted a follow-up survey to evaluate its accessibility and feature usefulness of this tool. In the survey, 77% of participants rated the EnVis interface as excellent, 92% of participants rated the CSV upload feature of EnVis as very clear and easy, and 92% of participants mentioned that they will use EnVis and recommend it to other environmental researchers. Overall, these results indicate that EnVis is a promising web-based visualization tool for environmental researchers to analyze and visualize large-scale dataset
The Impact of Attention Management Strategies on Ontask Behavior In Early Childhood Education: A Quantitative Single Case Study of Preschool Settings
No full textBACKGROUND: Attention is a critical cognitive process significantly influencing learning and task performance in preschoolers. Effective attention management can enhance engagement and reduce off-task behavior, essential for academic success.
OBJECTIVE: This study aimed to evaluate the impact of an attention management intervention on improving on-task behavior among preschool children aged 4-5 years. It was hypothesized that these strategies would significantly enhance child attention. METHOD: A quantitative single-case research design, specifically a multiple baseline across children aged 48-53 months, was employed to measure the impact of an Attention Management Intervention. The Attention Management Intervention consisted of verbal prompt and charts (Fisher et al., 2011), visual cues and verbal prompt (Mateo et al., 2020), physical movement breaks (Oberle et al., 2020) and mindfulness techniques (DiCarlo et al., 2020).
RESULTS: Results indicate that using the increase in attention leads to an increase in children’s on-task behaviors, which is consistent with previous research (Smith et al., 2014). CONCLUSIONS: The study provides empirical evidence that an Attention Management Intervention can be successfully used within the context of the normally occurring routines of the early childhood classroom to increase child attention.
Keywords: Child attention, preschool education, on-task behavior, verbal prompt, physical movements, mindfulness techniques, visual cues