Depth Fluctuations Research Articles

Reducing capillary depth fluctuations in high-speed laser welding of stainless steel using multi-core laser technology

Laser welding was carried out in AISI304 (X5CrNi18-10) stainless steel using a multi-core fiber laser. High-speed X-ray imaging was used to monitor the process. When employing core-power only (400W) at high welding speeds (12m/min), the capillary depth was found to be inconsistent. The capillary penetration into the material varied from approximately 0.8 mm to approximately 0.2 mm, with fluctuation periods of between single milliseconds and tens of milliseconds. Employing a 0.5:0.5 ring-core power distribution (390W:390W) to achieve the same penetration (0.8mm) was found to reduce fluctuations in the depth of the welding process and the capillary penetration. Possible reasons for this reduction in depth fluctuations are discussed together with a detailed description of the resulting changes in weld cross-section.

Lithospheric Folding Controls the Intracontinental Orogen of South China: Insight from Numerical Simulation

Abstract Orogenic processes worldwide have been attributed to various deformation mechanisms. However, the significance of lithospheric folding in these processes has often been overlooked and underestimated. Within the South China Block (SCB), a region marked by notable temporal and spatial variability in intracontinental deformation, the emergence of fold-and-thrust belts during the Paleozoic and Mesozoic periods has captured a scientific interest. The mechanisms governing the genesis of these belts remain a subject of debate, with no discernible subduction interface accounting for the extensive-scale fold-thrust deformation. Moreover, the SCB presents a substantial variation in lithospheric thickness, exceeding 100 km, offering a plausible mechanism for lithospheric folding. To interrogate this mechanism, we conducted lithospheric compression simulations via two-dimensional finite element methods, incorporating variable viscosity both laterally and vertically within the SCB. Our models elucidate that disparities in lithospheric strength beget distinctive deformational manifestation within the SCB. We observe that a weaker lithosphere tends to uplift, whereas a stronger lithosphere tends to subside during compression. Lithospheric strength also influences the Xuefengshan uplift and the spatial distribution of deformational features. In addition, lithospheric folding can account for crustal shortening and the presence of deep anomaly structures. A compelling correlation emerges between lithospheric folding and fluctuations in Moho depth and lithospheric thickness, suggesting its potential influence over the prolonged topographical evolution and shifts in depositional environments within the SCB. This study sheds new light on the role of lithospheric folding in the complex geodynamic history of the SCB and highlights its importance in understanding the broader context of orogenic processes worldwide.

Understanding the Importance of Daily Imaging in the Treatment of Non-Melanoma Skin Cancer with Image-Guided Superficial Radiation Therapy

Image-guided superficial radiation therapy (IGSRT) combines superficial radiation therapy (SRT) with full dermal visualization (FDV) via high-resolution dermal ultrasound (HRDUS) for the treatment of non-melanoma skin cancer (NMSC). The gold standard for IGSRT delivery includes a comprehensive cancer care model with support for dermatologists from a multidisciplinary team. When delivered in this model, IGSRT can achieve cure rates of 99% for treatment of NMSC. This paper focuses on the benefits of HRDUS used in conjunction with SRT for NMSC. Medical records from 7 dermatology clinics of 883 patients with 1507 cases of NMSC treated with IGSRT between 2017 and 2018 were retrospectively reviewed. In total, 92% of the NMSC lesions showed daily depth fluctuations, 60.32% of lesions did not require changes during therapy, and nearly 40% of lesions required at least one compensatory change during therapy. In total, 83% of NMSC lesions were labeled as high risk based on the 2024 NCCN guidelines. Increasing and decreasing tumor depth measurements during IGSRT inform dermatologists when adaptive changes in energy (kV), TDF, and dose will result in more efficacy and less toxicity, respectively.

High-speed synchrotron X-ray imaging of melt pool dynamics during ultrasonic melt processing of Al6061

Ultrasonic processing of solidifying metals in additive manufacturing can provide grain refinement and advantageous mechanical properties. However, the specific physical mechanisms of microstructural refinement relevant to laser-based additive manufacturing have not been directly observed because of sub-millimeter length scales and rapid solidification rates associated with melt pools. Here, high-speed synchrotron X-ray imaging is used to observe the effect of ultrasonic vibration directly on melt pool dynamics and solidification of Al6061 alloy. The high temporal and spatial resolution enabled direct observation of cavitation effects driven by a 20.2 kHz ultrasonic source. We utilized multiphysics simulations to validate the postulated connection between ultrasonic treatment and solidification. The X-ray results show a decrease in melt pool and keyhole depth fluctuations during melting and promotion of pore migration toward the melt pool surface with applied sonication. Additionally, the simulation results reveal increased localized melt pool flow velocity, cooling rates, and thermal gradients with applied sonication. This work shows how ultrasonic treatment can impact melt pools and its potential for improving part quality.

In situ x-ray imaging to understand subsurface behavior during continuous wave laser drilling

A limited understanding regarding the underlying dynamics and mechanisms of material removal during continuous wave laser drilling has presented significant challenges in achieving precision and process control. To address this, we employed high-fidelity, in situ synchrotron x-ray imaging to reveal previously unknown material behaviors during continuous wave laser drilling with power modulation. Our findings highlight that high-aspect ratio drill holes are achieved when the laser modulation frequency falls within the range of 8–12 kHz, provided that the laser average power and modulation amplitude levels meet the specified limits. Under these conditions, we identified a material removal mechanism driven by incremental accumulation of recoil pressure that gradually pushes material upward from deep within the substrate to the surface. This mechanism manifested as a low-frequency fluctuation in the vapor depression depth, resulting in periodic instances of material ejection. Furthermore, our study underscores that rapid expansion of the melt pool and the widening of the drill hole opening can impede effective material removal by redirecting energy from material ejection to increasing the melt pool size. This investigation contributes essential insights into the subsurface dynamics involved in the drilling of high-aspect ratio holes, furthering our fundamental understanding of this intricate process.

Porosity suppression mechanism analysis in narrow-gap oscillating laser-MIG hybrid welding of aluminum alloys based on keyhole stability and molten pool flow behavior

In this study, the keyhole dynamic behavior and molten pool flow were investigated to elucidate the effects of oscillating laser on porosity in narrow-gap oscillating laser-MIG hybrid welding of aluminum alloys. A weld with a porosity of 0.08% was produced at the laser oscillating frequency of 600 Hz and diameter of 1 mm, while 2.27% without oscillating laser. Compared to non-oscillating laser, keyhole opening size increased by about 2.3 times and keyhole depth fluctuation was suppressed. The forces acted on the interface between keyhole wall and molten pool became more balanced. The increased vapor recoil pressure overcame the combined closure effect of gravity and molten pool pressure. While applying oscillating laser, the vortex in molten pool was eliminated and the liquid metal flow was more stable. The combined impact force caused by droplets transfer and liquid metal convection due to constraining effect of narrow gap was buffered, which had less effect on molten pool and keyhole stability. The liquid metal tended to flow from the molten pool inside to surface, which favored the escape of bubbles from the molten pool.

Assessment of future trends and spatial orientation of groundwater resources as an essential climate variable in the Ganga basin

The dynamic climatic conditions, and anthropogenic activities have a significant impact on the Ganga basin, which is crucial for sustaining the eco-hydrological processes within the agricultural landscape of northern India. Additionally, the Ganga basin represents one of the largest and most densely inhabited aquifer systems globally. Inadequate management practices of groundwater in the current context are likely to contribute to a shortage of food insecurity in the near future. The multi-point statistics using non-parametric test based on the well data point for the period of 1996–2016, were analysed and geoprocessed for the seasonal (pre-monsoon, monsoon, post-monsoon) trend of groundwater depth, fluctuation, and drought in the Ganga basin. The zonal statistical mean of groundwater depletion/loss were maximum observed in post-monsoon season (10 ± 21 cm/year), followed by pre-monsoon(9 ± 22 cm/year), and monsoon (9 ± 21 cm/year). The groundwater depth fluctuation trend magnitude in the Ganga basin ranges from −0.57 m/year to 0.85 m/year, having mean of −0.01 ± 0.07 m/year. The areal percentage of the Ganga basin showing the groundwater drought propagation regions for the pre-monsoon, monsoon, and post-monsoon are found as 74.86%, 74.17%, and 78.52%, respectively. The severity of groundwater drought increased 22 times during pre-monsoon, 9 times in monsoon, and 7 times in the post-monsoon season from 1996 to 2016. The negative groundwater depth fluctuation leads to the groundwater mining at an alarming rate, and formation of dark zone. The decadal trend migration of the mean center shows high spatial variability based on the overexploitation of groundwater. The spatial mapping of declining depth, and increasing drought magnitude of groundwater leads to the groundwater scarcity in most of the regions, which could affect to achieve UN-SDG, Sendai Framework for Disaster Risk Reduction (SFDRR) (2015–2030).

Short rotation willow to restore degraded marginal land and enhance climate resiliency within the Prairie Pothole Region: A potential nature-based solution

Short rotation willow (SRW) is a land management strategy involving the cultivation of rapidly growing, biomass-rich herbaceous-woody plants. This practice holds promise for renewable energy production, water quality preservation, carbon sequestration, greenhouse gas (GHG) mitigation, enhancement of soil extracellular enzyme activities (EEAs), and promotion of overall soil health. The rapid growth of SRW demands substantial water and nutrient resources, posing concerns when cultivated in marginal riparian lands within the Prairie Pothole Region (PPR), potentially leading to alterations in groundwater table (GWT) depth fluctuations, elevated soil salinity levels, and disruptions to biogeochemical cycles. Hence, this study comprehensively evaluated the effects of establishing SRW as a degraded marginal riparian land use practice in the PPR and attempted to answer several vital questions in the field and microcosm scale on soil hydrology, salinity, nutrients, soil organic carbon (SOC), GHG emissions, and EEAs involved in biogeochemical cycling. In a field experiment, the effects of SRW were evaluated by measuring the depth to GWT, groundwater and soil electrical conductivity (EC), macronutrients (N, P, K, and S), and SOC content in different fractions and chemical compositions during the first rotation (3-year cycle) compared with adjacent annual crop and pasture in two semi-arid PPR sites. In a microcosm experiment, GHG (CO2, CH4, and N2O) emissions and EEAs [β-glucosidase (BG), N-acetyl glucosaminidase (NAG), and alkaline phosphatase (AP)] were measured in intact soil cores treated with declining water tables and different groundwater salinity levels. No consistent land use impacts on GWT or soil EC were observed between sites. Land use in site B significantly impacted GWT depth, implying site-specific factors, such as topography and soil characteristics, may be dominant over land use effects. Under SRW, the levels of macronutrients in the soil varied but did not significantly reduce the overall nutrient content of the soil. Total SOC was highest in pasture; light fraction organic carbon and particulate organic carbon followed a similar land use pattern, i.e., pasture > SRW = annual crop. Land uses affected GHG emissions significantly in the order of pasture > annual crop = SRW. GHG emission varied with salinity and GWT but there was no interaction with land use practices. Soil EEAs were significantly impacted by different land uses, i.e., pasture > annual crop = SRW, suggesting that the effects resulted from associated SOC. Our microcosm experiment suggests that the SRW land use practice holds promise as a sustainable Nature-Based Solution for enhancing climate resiliency in PPR. It exhibits a lower global warming potential compared to annual crop and pasture. Therefore, widespread implementation of the SRW land use practice in degraded marginal land could help mitigate the effects of climate change in the region.

Response of Functional Traits of Aquatic Plants to Water Depth Changes under Short-Term Eutrophic Clear-Water Conditions: A Mesocosm Study.

Aquatic plants play a key role in the structuring and functioning of shallow lake ecosystems. However, eutrophication often triggers shifts in plant communities and species diversity, especially in the early stages when the water is still clear. Additionally, water depth is an important factor regulating aquatic plant communities. We conducted a 50-day mesocosm study to investigate how water depth (50 cm and 100 cm) affected the functional traits (vertical expansion versus horizontal colonisation) of 20 aquatic plants under eutrophic clear-water conditions. Among the selected species, the submerged plants Hydrocotyle vulgaris and Limnophila indica exhibited higher plant height or biomass in deeper water, while the emergent plants Myriophyllum aquaticum showed the opposite trend. Additionally, Ludwigia peploides subsp. stipulacea exhibited better vertical growth than the remaining species, and the submerged species Vallisneria denseserrulata had better horizontal colonisation. There was a positive correlation between plant height and rhizome length, indicating the absence of a trade-off between vertical growth and horizontal expansion. Our findings suggest an overall resilience of aquatic plants to varying water depths within our study range and highlight the importance of analysing functional traits when selecting appropriate species in freshwater ecosystem restoration, particularly in the face of climate change-induced water depth fluctuations.

Design of an Overhead Water Tank as a Passive Tuned Damper Using an Innovative Support System Adaptive to Liquid Depth Fluctuation in the Tank

Difficulty in maintaining tuning due to water depth fluctuation makes overhead water tanks (OWTs) ineffective as tuned liquid or mass dampers. Recently, a semi-active damper involving OWT, that varies the stiffness of the tank-supporting columns with liquid depth variation to maintain the impulsive frequency of the tank constant at a value required for tuning, has been proposed. In this paper, the concept is extended to develop a passive tuned damper involving the OWT (PTD-OWT), which is more reliable, cost-effective, and has a simpler configuration than its semi-active counterpart but achieves the same objective as the latter. For the PTD-OWT, a novel mechanism involving a spring-supported platform, a rigid frame, and tank-supporting columns is developed. The working principle and mathematical model of the PTD-OWT are presented followed by an illustrative design example considering the host building undergoing base excitation. The results revealed that the PTD-OWT remains tuned and thereby performs consistently despite wide variations in water depth in the tank. Significant reductions have been achieved by the PTD-OWT in peak and root-mean-square displacement and acceleration responses of the structure for a variation in liquid depth between 100% full tank to empty tank condition, with the maximum fall in control achieved as only 6.8%. A comparison of PTD-OWT is made with the case when the tank is designed as a conventional passive tuned mass damper (TMD) without the provision for maintaining tuning. The conventional mass damper suffers significant performance degradation as liquid depth fluctuates in the tank.

Gap in Noise Auditory Brainstem Responses: A Systematic Review

Background and Objectives: The gap in noise auditory brainstem responses (GIN-ABR) is a valuable assessment tool for auditory temporal processing, offering non-invasive and objective measurements encompassing the entire auditory system from the cochlea to the brainstem. This method has been utilized in investigating various factors, including age-related effects, hearing loss, and tinnitus. This systematic review was conducted to present a thorough examination of (GIN-ABR), encompassing its methodology, applications, and inherent limitations. Methods: This study was conducted based on preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Cochrane, PubMed, and Ovid databases were used to extract English articles from 1990 to June 2023. The search terms used were “gap in noise auditory brainstem response”, “ABR gap detection”, “ABR gap duration”, “ABR gap threshold”, and “ABR temporal processing”. Articles were included if gap-evoked ABR was used, investigating the effect of any factor on the responses, and using any gapped stimulus type. Articles whose evoked potentials did not include ABR waves were excluded. The outcome of interest was gap-evoked ABR in different participant groups. Results: A total of 10 studies were deemed suitable for inclusion in the review. The articles were reviewed that including the study population, the methods, and the results. Despite the variability in the results of the studies, in the aged group, longer latency shifts and decreased peak amplitude were reported compared to the young group. Correspondence of behavioral thresholds with GIN-ABR has also been mentioned in studies. Conclusion: The GIN-ABR method has been extensively utilized in investigating various factors, including age-related effects, hearing loss, and tinnitus. Notably, GIN-ABR has several clinical advantages, such as cost-effectiveness, shorter test duration, independence from alertness levels, attention, sleep depth fluctuations, or medication. Additionally, it has shown its compatibility with psychophysical tests. Further research is warranted to explore the impact of various factors on different components of GIN-ABR. Consequently, with its promising findings and growing body of research, the gap in noise test has the potential to be gradually integrated into the set of audiological clinical evaluations.

A discussion on carbon and oxygen isotopes of secondary carbonates in loess-paleosol sequences

Although carbon and oxygen isotopic compositions of carbonates are valuable for Quaternary climate reconstruction due to their sensitivity to paleoclimate changes, a comprehensive understanding regarding the formation, factors influencing isotopic variations, and age uncertainties of secondary carbonates in loess deposits remains elusive. This study investigates the microstructure and stable isotopes of secondary carbonates, specifically calcified root cells (CRC) and needle-fiber calcite (NFC), found within the loess deposits of the last glacial period in the northwestern region of the Chinese Loess Plateau. The average δ13C values of soil total organic matter, CRC, NFC, and total inorganic carbonates in the YuanBao sections are −22.1‰, −14.9‰, −7.0‰, −4.6‰, respectively. Radiocarbon dating results reveal that both CRC and NFC were not of synsedimentary origin. The pronounced negativity of the carbon isotopic composition and the microstructures offer insights that CRC formation is closely tied to C3 plants. The synchronous depletion of δ13CCRC and δ18OCRC values during the transition period from the last glacial to the Holocene, underscores the sensitivity of isotopic composition of CRC to local environmental changes, making it a potential candidate for paleo-climate studies. Additionally, CRC formed during the glacial period provides a close approximation to the true sedimentation age. The radiocarbon dating of NFC highlights a significant fluctuation in carbon source translocation depth, resulting in a pronounced temporal and spatial decoupling between NFC formation and the surrounding deposits. Consequently, values of δ13CNFC and δ18ONFC seem to exhibit no significant trend across the limited depth range in this research. We propose that, when using NFC for paleoclimate reconstruction, careful consideration of variations in translocation depths of carbon sources is imperative to prevent misestimations. NFC could potentially be more fitting for broader temporal-scale paleoclimate reconstructions rather than high-resolution investigations.

Recent hummock establishment in the margin of a subarctic fen, Finnish Lapland

Northern fens, that host unique biota and form a remarkable carbon stock, are sensitive to changes in the moisture balance and, therefore, may be strongly affected by climatic fluctuations. However, long‐term monitoring and palaeoecological studies of fens are relatively rare and, as a result, their responses to past and current climatic fluctuations are poorly known. In this study, we examined the recent vegetation change as well as changes in testate amoeba communities in the mire margin of a subarctic fen in Finnish Lapland with four peat profiles. Testate amoebae were used as indicators of past fluctuations in water table depth. The vegetation showed a drastic shift from sedge‐dominated fen to Sphagnum‐dominated communities during the late 20th and the early 21st centuries. This shift was accompanied by a turnover in the testate amoeba community. Testate amoeba‐based water table reconstructions indicated recent drying. This may be due to the lowering of the water table either from accelerated Sphagnum increment or enhanced evaporation. The observed hummock establishment concurs with the documented hemisphere‐wide expansion trend of hummock communities in fens. This change may strengthen the carbon sink and storage capacity of these peatlands, which could be viewed as a welcome negative feedback process to the ongoing climate warming. However, the change also poses a threat to biodiversity since fens are not only species‐rich habitats but are also endangered ecosystems.

MAGICIAN: MAG simulation for investigating criteria for bioinformatic analysis

BackgroundThe possibility of recovering metagenome-assembled genomes (MAGs) from sequence reads allows for further insights into microbial communities and their members, possibly even analyzing such sequences with tools designed for single-isolate genomes. As result quality depends on sequence quality, performance of tools for single-isolate genomes on MAGs should be tested beforehand. Bioinformatics can be leveraged to quickly create varied synthetic test sets with known composition for this purpose.ResultsWe present MAGICIAN, a flexible, user-friendly pipeline for the simulation of MAGs. MAGICIAN combines a synthetic metagenome simulator with a metagenomic assembly and binning pipeline to simulate MAGs based on user-supplied input genomes, allowing users to test performance of tools on MAGs while having a ground truth to compare results to. Using MAGICIAN, we found that even very slight (1%) changes in depth of coverage can drastically affect whether a genome can be recovered. We also demonstrate the use of simulated MAGs by evaluating the suitability of such genomes obtained with MAGICIAN’s current default pipeline for analysis with the antimicrobial resistance gene identification tool ResFinder.ConclusionsUsing MAGICIAN, it is possible to simulate MAGs which, while generally high in quality, reflect issues encountered with real-world data, thus providing realistic best-case data. Evaluating the results of ResFinder analysis of these genomes revealed a risk for plausible-looking false positives, which underlines the need for pipeline validation so that researchers are aware of the potential issues when interpreting real-world data. Furthermore, the effects of fluctuations in depth of coverage on genome recovery in our simulated “random sequencing” warrant further investigation and indicate random subsampling of reads may affect discovery of more genomes.

Fluctuations in depth and associated primes of powers of ideals

Fluctuations in depth and associated primes of powers of ideals

Analysis of line spectral fluctuation characteristics for source depth discrimination in shallow water

The difference in intensity fluctuation between a surface signal and a submerged signal can be used to discriminate the source depth in the shallow water waveguide. However, the properties of fluctuation distinction in intensity between surface source and submerge source are rarely studied, resulting in the poor performance of fluctuation-based methods sometimes. In this work, the intensity fluctuations caused by source depth fluctuations is analyzed by differential method and variance statistics method to figure out the physics of intensity fluctuations, and to present the suitable quantity for depth discrimination. Firstly, the derivative expression of real part, power and amplitude of the pressure field are respectively derived from the normal mode theory, hence their fluctuation quantities are specified. Then, the numerical examples, including the factor of receiver depth, source frequency and source range, are treated to verify the derivation and summarize the characteristic of fluctuations. The property of the intensity fluctuations is also compared with the distribution of normalized quantity on the depth dimension. Finally, the SWellEx-96 experimental data processing results validate the conclusions. The processing results of derivation, simulation data and experimental data show that the interactions between modes excited by the source give rise to the fluctuations. Meanwhile, the property of the interactions is affected by the received depth, source range and source frequency. Amplitude is capable of building a quantity based on fluctuations for source depth discrimination. For surface and submerged sources with lower frequency, their distinction in their fluctuations is stably represented by amplitude. In the SWellEx-96 experiment, the normalized values calculated from the amplitude of surface noise and submerged sound sources show the lowest difference of 0.5 and the highest difference of 2.5, indicating the effectiveness of using amplitude fluctuations to discriminate the sound source depth.

Evaluation of AnnAGNPS Wetland Nitrogen Removal Component on Farmed Prairie Potholes

Highlights AnnAGNPS offers a wetland module (AgWET) to simulate farmed prairie potholes soluble nitrogen dynamics. Three key parameters of the AgWET nitrogen removal components show high and very high Relative Sensitivity (Sr ). AnnAGNPS tends to underestimate the soluble nitrogen concentration at the beginning of the cropping season. Abstract. Farmed prairie potholes are common in northern Iowa and have been considered an impediment to agricultural development. Potholes have distinctive wetland characteristics where they might contain a high concentration of soluble nitrogen coming from agricultural upland runoff. With sub-surface drainage underneath them, providing short circuit nutrient transport downstream, Iowa poses a significant threat to nitrogen export to the Gulf of Mexico. Watershed models, such as AnnAGNPS, developed a wetland module allowing users to find the possible BMPs to accomplish nutrient reduction targets. Previous research indicates that AnnAGNPS may be used to mimic inundation depth fluctuations in potholes with moderate success. However, there has been little research on the wetland nitrogen removal components of the model. This study aims to evaluate the AnnAGNPS wetland module's performance in simulating the soluble nitrogen concentration in three farmed prairie potholes by comparing the simulation output with the observed data. The sensitivity analysis of the three key parameters of the model shows high and very high levels of sensitivity, with the temperature coefficient's relative sensitivity ranging from -6.7 to 8.6. Attempts in parameterization on the three targeted parameters indicated that the model poorly simulated the soluble nitrogen concentration. The comparison between observed and simulated data shows that the model fails to predict the high concentration of soluble nitrogen in the early cropping season. This conclusion is consistent with earlier research indicating that AnnAGNPS tends to underestimate the nitrogen concentration during the cropping season. Keywords: AnnAGNPS wetland module, Farmed prairie pothole, Soluble nitrogen concentration.

Spatiotemporal Variation and Long-Range Correlation of Groundwater Levels in Odessa, Ukraine

Increasing groundwater levels (GWLs) may become one of the most serious issues for the city of Odessa, Ukraine. This study investigated the spatial distribution characteristics and multifractal scaling behaviour of the groundwater-level/-depth fluctuations for a Quaternary aquifer in the city of Odessa using a geostatistical approach and multifractal detrended fluctuation analysis (MF-DFA). These two methods were applied to monthly GWL fluctuation time series from 1970 to 2020 to monitor 72 hydrogeological wells situated in different parts of the city of Odessa. The spatial distribution of the GWLs revealed an overall trend of decline and recovery from 1970 to 2020 in the study area, except for most of the southern region, where a persistent recovery of the groundwater depth was observed. The MF-DFA results suggest that the dynamics of the GWL fluctuations have multifractal characteristics in the Odessa area. In addition, both long-range correlations and fat-tail probability distribution contribute to the multifractality. However, long-range correlations among the fluctuations made a major contribution to the observed multifractality of the GWL fluctuation time series. The generalised Hurst exponents show a wide range of change (0.20 < h(q) < 2.85), indicating the sensitivity of the GWL fluctuations to changes in small-scale factors and large-scale factors. Regarding the long-range correlations of the GWL depths, the Hurst exponents (q = 2) demonstrated the positive persistence of groundwater-depth recovery in the southern region and the persistence of groundwater-depth variation in the other regions of the study area. The dynamic changes in the GWL depths in the Odessa area may be influenced by both natural and anthropogenic factors.

A new metric for sunlight exposure in rivers, lakes, and oceans

AbstractVertical motion is an important driver of sunlight exposure in aquatic environments, shaping the growth and fate of materials and organisms. We derive a simple model accounting for turbulent depth fluctuations of particles to predict the depth that contributes the most sunlight exposure (effective depth) as well as the single depth that, if measured at one place over time, produces the same total sunlight exposure as a moving particle (functional depth). Field measurements of light and depth in rivers using neutrally buoyant drifters and buoys validate our model. Effective depth varied from 0.1 to 1.5 m below the water surface and was ~ 30% of the overall water depth on average. Functional depth varied from 0.67 to 2.3 m and was ~ 50% of the overall water depth on average. Functional and effective depth are physically based concepts incorporating turbulent motion, spatial variability, and water clarity offering new approaches to characterize light exposure in aquatic environments.

Turbulent Structure in Supernova Remnants G46.8−0.3 and G39.2−0.3 from THOR Polarimetry

We present the continued analysis of polarization and Faraday rotation for the supernova remnants (SNRs) G46.8−0.3 and G39.2−0.3 in L-band (1–2 GHz) radio continuum in The H i/OH/Recombination line (THOR) survey. In this work, we present our investigation of Faraday depth fluctuations from angular scales comparable to the size of the SNRs down to scales less than our 16″ beam (≲0.7 pc) from Faraday dispersion (σ ϕ ). From THOR, we find median σ ϕ of 15.9 ± 3.2 rad m−2 for G46.8−0.3 and 17.6 ± 1.6 rad m−2 for G39.2−0.3. When comparing to polarization at 6 cm, we find evidence for σ ϕ ≳ 30 rad m−2 in localized regions where we detect no polarization in THOR. We combine Faraday depth dispersion with the rotation measure (RM) structure function (SF) and find evidence for a break in the SF on scales less than the THOR beam. We estimate the RM SF of the foreground interstellar medium using the SF of extragalactic radio sources and pulsars to find that the RM fluctuations we measure originate within the SNRs for all but the largest angular scales.