Variation In Rates Research Articles

Urban primacy and slum prevalence in Latin American and Caribbean countries in the 1990-2020 period

Slums are a global concern due to their impact on urban health and urban planning. Although Latin America and the Caribbean is one of the most urbanized developing regions, slums are still a significant concern. However, most studies have concentrated on a single city, using a sample of Latin American and Caribbean (LAC) countries or treating the region as one unit to analyze income inequality and urban primacy. Here, we present an analysis of the relationship between slums and urban primacy for LAC countries for the 1990–2020 period, controlling for GDP per capita and public spending on housing. In addition, we model the relationship between slums and demographic variables such as the fertility rate, migration rate, and urbanization. e analysis is based on panel data from the World Bank and e Economic Commission for Latin America and the Caribbean (ECLAC). During the period of study, a clear positive relationship is evident between urban primacy in the largest city and the slum rate in each LAC country. However, a high level of heterogeneity is observed in this relationship and our model explains the variation in the slum rate within countries better than the variation between countries.

Elucidating Heterogeneous Li Insertion Using Single-Crystalline and Freestanding Layered Oxide Thin Film.

The kinetics of interfacial ion insertion govern the uniformity of electrochemical reactions, playing a crucial role in lithium-ion battery performance. In two-dimensional lithium-conducting layered-oxide battery particles, variation in insertion rates across insertion channels remains unclear due to poorly defined crystal orientation at the solid-liquid interface and solid-state-lithium-diffusion length. This ambiguity complicates understanding inhomogeneous lithium-insertion channels activation. A systematic study requires crystallographically predefined interfaces and in situ lithium-concentration mapping. Here, we fabricated a freestanding, (104)-oriented-LiNi1/3Mn1/3Co1/3O2 single-crystal thin film using dissolution-induced release and performed in situ scanning-transmission-X-ray-microscopy to spatially resolve lithium-insertion at well-defined-interfaces. We observed heterogeneous lithium-concentration evolution due to channel-by-channel insertion rate variation, despite the potential for homogeneous lithium distribution via a solid-solution-phase at equilibrium in NMC111. Increasing current density exacerbates this heterogeneity, highlighting channel-by-channel variation. Our findings provide critical insights into battery electrode utilization and lifetime management, potentially guiding the design of more efficient and durable lithium-ion batteries.

Numerical analysis of mixing performance in Y-junction mixers and its impact on yields from supercritical water hydrolysis

This study investigates the mixing behavior in a Y-junction mixer for supercritical water hydrolysis using large eddy simulation with a discrete phase model. Yield changes were simulated using a two-step reaction model with first-order kinetics, based on particles’ temporal temperature data. Effective mixing produced closely matched mass and particle flow temperature distributions, both exhibiting bell-shaped profiles near the mixed temperature. Although variations in flow rate within ±25 % and changes in the inlet temperatures of supercritical water from 350 °C to 430 °C and subcritical water from 100 °C to 170 °C did not significantly affect the overall mixing performance, they did alter the mixed temperature and, subsequently, yield changes. Additionally, backflow occurred when Richardson number for the subcritical inlet reached approximately 7. In effective mixing, simulated yields were approximately 15 % lower than the ideal theoretical yields, calculated using the reaction rate constant at the mixed temperature.

Trends in Road Traffic Injuries Mortality in India: An Analysis from the Global Burden of Disease Study 1990-2021.

Road traffic injury (RTI) is one of the most common causes of accidental deaths in India. The study investigates the changes in trends in age-standardised RTI mortality rates in India by sex and age groups, using data from the Global Burden of Disease (GBD) Study 2021. The trend segments are estimated from 1990 to 2021 employing a joinpoint regression model. Additionally, the influence of age, time period, and birth cohort on mortality rate trends was assessed using the age-period-cohort model. Over the past 32 years, the RTI mortality rates have experienced multiple trend segments. RTI mortality rate in the ≤ 14-year-old population has declined remarkably, dropping from 5.71 (4.65 to 6.88) per lakh population in 1990 to 3.66 (3.01 to 4.35) per lakh population in 2010, and further declining to 1.98 (1.65 to 2.37) per lakh population in 2021. The study found a positive correlation between RTI mortality rates and age, with rates consistently lower for women compared to men across all age groups. The variation in RTI mortality rates across Indian states has widened over time, with the coefficient of variation increasing from 30.58% in 1990 to 32.36% in 2010, and further to 35.11% in 2021. Despite efforts, Indian states are unlikely to achieve the goal of halving RTI deaths by 2030, based on 2010 levels. To address this, road conditions and road safety policies aimed at preventing the incidence of RTIs should be further intensified.

Evaporative characteristics of winter wheat in the guanzhong loess plateau region of shaanxi, china

This study explain the evaporative characteristics of winter wheat in the Guanzhong Loess Plateau region of Shaanxi through stem flow meters and weighing lysimeters. It examines the diurnal variations in evapotranspiration rates, leaf area index, and soil moisture's impact on winter wheat evaporation. Additionally, it explores the ratio of transpiration to evaporation and compares the evaporation measured by the water balance method with that of the lysimeters. The findings reveal distinct diurnal variations in transpiration rates under different weather conditions, with sunny days exhibiting an unimodal curve while cloudy and rainy days showcase irregular multi-peaked curves. The evaporation curve generally follows an unimodal pattern, with both leaf area index and soil moisture significantly influencing the evaporation process. From heading to early grain filling, the ratio of transpiration to evaporation ranges from 80.3 to 83.4%. Evaporation obtained through the water balance method (0-220 cm) is 6% less than that measured by the lysimeters. Bangladesh J. Bot. 53(3): 689-695, 2024 (September) Special

Glomerular Filtration Rate and Blood Urea Nitrogen Levels between Coastal and Desert Regions within Libya

Background: Limited research exists on how geographic location and environmental factors influence kidney function. This study investigates potential variations in Glomerular Filtration Rate (GFR) and Blood Urea Nitrogen (BUN) levels between individuals residing in the coastal and desert regions of Libya. Methods: An observational, retrospective analysis was conducted using medical records. Participants (n=260) were recruited from Benghazi (coastal) and Jalu/Samnu/Sabha (desert) regions. Inclusion criteria included age range (18-90 years) and residency in the designated location. Exclusion criteria focused on factors affecting GFR (e.g., pre-existing kidney disease). GFR was estimated using the CKD-EPI formula. BUN levels were obtained from medical records. T-tests and Mann-Whitney U tests were used for statistical analysis. Results: The final sample size (after exclusions) and participant demographics was 134 participants. The study found no statistically significant difference in GFR between the coastal and desert groups (p-value = 0.238). However, BUN levels were significantly higher in the desert group (mean = 28.2 SD = 30.5) compared to the coastal group (mean = 15.5, SD = 10.5) with a p-value of (p-value = 0.026). Conclusion: This study did not identify a significant association between GFR and geographic location (coastal vs. desert) within Libya. However, BUN levels were significantly higher in the desert population, suggesting potential differences in kidney function or contributing factors that warrant further investigation.

Review of high-precision femtosecond laser materials processing for fabricating microstructures: Effects of laser parameters on processing quality, ablation efficiency, and microhole shape

Femtosecond lasers are promising tools for achieving high-precision processing of thin materials without causing any thermal surface damage and bulk distortion. However, thermal damage can occur even with ultrashort laser pulses. This is because of high electron penetration depth and heat accumulation at high fluence and high repetition rate. Nanoparticle redeposition can be dramatically altered with variation in repetition rate. The symmetry of microholes and ablation efficiency vary with laser polarization. The laser wavelength affects the ablation efficiency and surface roughness. Therefore, understanding these laser–matter interactions that depend on the laser parameters is essential for high-precision laser processing. This article reviews laser–matter interactions in the 64FeNi alloy, as well as analytical models for designing the desired hole size and taper angles. This can help establish strategies for creating various high-precision microstructures using femtosecond lasers.

Tinnitus Suppression with Electrical Stimulation at the Most Basal Contact of the Cochlear Implant Electrode as a Model for Round Window Stimulation.

The objective of this research was to test whether efficient tinnitus suppression could be achieved by electrical stimulation of the single most basal electrode contact of a cochlear implant. This approach simulates the effects of electrical stimulation using a round-window electrode. The study was performed in 10 adult cochlear implant patients showing complete or almost complete tinnitus suppression during electrical stimulation with their standard fitting-MAP. In all patients, tinnitus appeared again when the implant was switched off. Five Nucleus implant (1 CI532, 4 CI24RE CA) users and 5 Mi12xx series with FLEX28 electrodes with at least 6 months of CI experience were included. Two types of stimulation were presented at the most basal CI contact: a constant pulse train and a modulated pulse train. The variation in pulse rates was low rate (100-300 pps) and high (≥900 pps), and the current level ranged from the C-level to less than the T-level for both stimulation types. The effect of acute electrical stimulation at the most basal electrode contact was compared to the effect obtained with multichannel stimulation with the patient's current fitting MAP. Electrical stimulation was paused between tests with different stimulation types until tinnitus returned to baseline intensity. Patients reported Visual Analog Scale (VAS) scores for tinnitus loudness and intrusiveness during normal CI use and for each single contact stimulation type. Eight participants perceived complete suppression with one or more stimulation patterns. In 2 patients, suppression was less efficient than full-band CI stimulation. Louder stimuli are generally perceived as annoying and less effective in reducing tinnitus. In FLEX28 patients, it was also possible to obtain full tinnitus suppression with current amplitudes under the thresholds for auditory perception (this was not tested in patients with the Nucleus device). In 8 of the 10 included patients, we were able to obtain complete or almost complete tinnitus suppression with electrical stimulation at only 1 most basal electrode contact. Therefore, round-window stimulation with a single electrode may be a potential treatment for tinnitus in patients with significant residual hearing. The long-term effects of this therapy should be confirmed in future studies.

Intragenomic conflicts with plasmids and chromosomal mobile genetic elements drive the evolution of natural transformation within species.

Natural transformation is the only mechanism of genetic exchange controlled by the recipient bacteria. We quantified its rates in 786 clinical strains of the human pathogens Legionella pneumophila (Lp) and 496 clinical and environmental strains of Acinetobacter baumannii (Ab). The analysis of transformation rates in the light of phylogeny revealed they evolve by a mixture of frequent small changes and a few large quick jumps across 6 orders of magnitude. In standard conditions close to half of the strains of Lp and a more than a third in Ab are below the detection limit and thus presumably non-transformable. Ab environmental strains tend to have higher transformation rates than the clinical ones. Transitions to non-transformability were frequent and usually recent, suggesting that they are deleterious and subsequently purged by natural selection. Accordingly, we find that transformation decreases genetic linkage in both species, which might accelerate adaptation. Intragenomic conflicts with chromosomal mobile genetic elements (MGEs) and plasmids could explain these transitions and a GWAS confirmed systematic negative associations between transformation and MGEs: plasmids and other conjugative elements in Lp, prophages in Ab, and transposable elements in both. In accordance with the hypothesis of modulation of transformation rates by genetic conflicts, transformable strains have fewer MGEs in both species and some MGEs inactivate genes implicated in the transformation with heterologous DNA (in Ab). Innate defense systems against MGEs are associated with lower transformation rates, especially restriction-modification systems. In contrast, CRISPR-Cas systems are associated with higher transformation rates suggesting that adaptive defense systems may facilitate cell protection from MGEs while preserving genetic exchanges by natural transformation. Ab and Lp have different lifestyles, gene repertoires, and population structure. Nevertheless, they exhibit similar trends in terms of variation of transformation rates and its determinants, suggesting that genetic conflicts could drive the evolution of natural transformation in many bacteria.

Transient flow and noise characteristics of vortex-turbulence-noise interaction in centrifugal pump

Centrifugal pump operation noise is an avoidable common phenomenon in engineering practices, and its characteristics are closely influenced by the flow characteristics of the fluid. In this paper, a numerical simulation of centrifugal pump operation with different flow rates is carried out using the detached eddy simulation turbulence model and compared with the experimental results. Then the noise source and far-field radiated noise characteristics of the centrifugal pump are investigated using Lighthill’s analogy. The results show that the noise of centrifugal pump is closely related to the flow characteristics of impeller, especially the generation and development of vortex. The relationship between turbulent kinetic energy (TKE) and vortex is complex, involving the generation, development and shedding of vortex. The influence of flow rate variation on vortex structure in impeller is studied by vortex transport equation. It is found that the relative vortex stretching (RVS) term is the main driving force of vortex distribution. The distribution of the Coriolis force (CORF) term is mainly concentrated in the inlet and outlet areas of the flow channel, which is related to the rotational motion of the impeller and the dynamic characteristic of the fluid. The power spectral density inside the impeller is mainly concentrated in the low frequency region, indicating that the low frequency noise component is dominant in energy. The directivity curve of far-field noise pressure level is influenced by hydrodynamic effect, impeller rotation direction and pump design structure, and will have a certain deviation. The spectral curve analysis of velocity, vorticity, pressure and sound pressure level shows that these physical quantities have strong correlation on the spectrum, in which the low frequency component is large, and the high frequency component is complex and volatile.

The Effects of Sedation on Auditory Brainstem Response in Pediatric Population: A Systematic Review

Background and Aim: Auditory Brainstem Response (ABR) is crucial for evaluating auditory pathway function in pediatric patients. However, obtaining reliable ABR measurements in young children can be challenging due to their inability to stay still and quiet during the test. Sedation is frequently used to facilitate ABR testing in this population, but the most practically effective sedation method and its impact are still uncertain. This systematic review aimed to thoroughly investigate the success rates (completion of ABR in both ears) associated with different sedation techniques. Recent Findings: In recent review (2000-2022), Ten studies, identified through a comprehensive search of electronic databases, were included in the analysis. The studies reported significant variation in success rates for ABR testing with sedation, ranging from 70% to 100%. This suggests that the effectiveness of sedation may not be uniform across all situations. The included studies employed a wide variety of sedation techniques, highlighting the lack of a standardized approach in this area. Conclusion: These findings highlight the heterogeneity in sedation practices and success rates for pediatric ABR testing. This emphasizes the importance of tailoring the sedation approach to the specific needs of each child while carefully considering the potential risks associated with each sedation method. Further research is warranted to establish standardized protocols for sedation in pediatric ABR , ensuring optimal test efficacy while prioritizing patient safety. Research Square registration.Keywords: Auditory brainstem response; sedation; chloral hydrate; children; dexmedetomidine; intranasal drug administration

Concurrent photothermal therapy and nuclear magnetic resonance imaging with plasmonic–magnetic nanoparticles: A numerical study

Background and Objective: Theranostics is the combination of the diagnostic and therapeutic phases. Here we focus on simultaneous use of photothermal therapy and magnetic resonance imaging, employing a contrast-photothermal agent that converts incident light into heat and affects the transverse relaxation time, a key magnetic resonance imaging parameter. Our work considers a gold–magnetite nanoshell platform to gauge the feasibility of magnetic resonance imaging monitoring of the heating associated with phototherapy, by studying the modification of the transverse relaxation rate induced by laser illumination of a solution containing these hybrid nanoparticles. Methods:We simulate a system composed of an aqueous solution with hybrid nanoshells under continuous laser irradiation, enabling the evaluation of spatial variations of the transverse relaxation rate within the sample. We work with the hybrid nanoshell platform comprising a metal/gold shell for thermoplasmonic effects and a magnetite core for magnetic resonance imaging contrast enhancement. The optical properties of the nanoshells are first obtained through simulations using the finite element method. Next, the heating generated by the laser illumination is calculated by numerical integration. Finally, the transverse relaxation rate is obtained through the application of an analytical model. Additionally, we conduct an optimization of the nanoshell geometry to fulfill requirements of both magnetic resonance imaging and phototherapy techniques. Results:Our findings demonstrate a narrow range of nanoshell sizes exhibiting both a plasmonic absorption peak in the human biological window and a high response to laser illumination of the transverse relaxation rate. Furthermore, the illumination can induce up to a 30% modification in transverse relaxation rate compared to the non-illuminated scenario in this range of nanoshell sizes. Conclusions:In this work we establish the numerical understanding of the interplay between phototherapy and nuclear magnetic resonance imaging when employed concurrently. This allows magnetic resonance imaging monitoring of the heating associated with phototherapy.

Wearable Hydrogel SERS Chip Utilizing Plasmonic Trimers for Uric Acid Analysis in Sweat.

Uric acid is typically measured through blood tests, which can be inconvenient and uncomfortable for patients. Herein, we propose a wearable surface-enhanced Raman scattering (SERS) chip, incorporating a hydrogel membrane with integrated plasmonic trimers, for noninvasive monitoring of uric acid in sweat. The plasmonic trimers feature sub 5 nm nanogaps, generating strong electromagnetic fields to boost the Raman signal of surrounding molecules. Simultaneously, the hydrogel membrane pumps sweat through these gaps, efficiently capturing sweat biomarkers for SERS detection. The chip can achieve saturation adsorption of sweat within 5 min, eliminating variations in individual sweat production rates. Dynamic SERS tracking of uric acid and lactic acid levels during anaerobic exercise reveals a temporary suppression of uric acid metabolism, likely due to metabolic competition with lactic acid. Furthermore, long-term monitoring correlates well with blood test results, confirming that regular exercise helps reduce serum uric acid levels and supporting its potential in managing hyperuricemia.

Late Quaternary slip rate of the strike-slip faults on the eastern margin of the Qaidam Basin on the Tibetan Plateau and its implication on regional strain partitioning

The spatial variation in slip rates of large-scale strike-slip faults provides crucial support for the conceptual models of continental collision. However, the reasons for the decrease in slip rate of the East Kunlun Fault at the eastern margin of the Qaidam Basin on the Tibetan Plateau are still unclear. At the eastern margin of the Qaidam Basin, we identified four active strike-slip faults—two NW-SE−orientated dextral (the Xiariha Fault and Yingdeerkang Fault) and two E-W−orientated sinistral (the Reshui-Taosituohe Fault and Taosituohenan Fault)—and determined their slip rates using uncrewed aerial vehicle-based topography and optically stimulated luminescence dating. For the Xiariha Fault, from north to south slip rates are 1.39 +0.51/−0.34 mm/yr, 1.19 +0.15/−0.14 mm/yr, and 0.9 +0.19/−0.16 mm/yr. The Yingdeerkang Fault slips at 0.66 +0.08/−0.07 mm/yr. The Reshui-Taosituohe Fault, from west to east, slips at 0.95 +0.22/−0.19 mm/yr and 1.20 +0.11/−0.09 mm/yr. The Taosituohenan Fault, west to east, slips at 0.62 +0.12/−0.12 mm/yr to 1.01 +0.21/−0.19 mm/yr and 1.21 +0.43/−0.25 mm/yr. We believe that the gradual decrease in slip rate of the East Kunlun Fault at the Tuosuo Lake segment toward the east is influenced by the activity of the four active strike-slip faults with a slip rate of ∼1 mm/yr along the eastern margin of the Qaidam Basin and the Elashan Fault. The decrease in fault slip rate is not solely attributed to the diverse structural styles of the fault itself but also to the strain absorption by the development of differently oriented faults around its periphery.

Phosphorus limitation regulates the responses of microbial carbon metabolism to long-term combined additions of nitrogen and phosphorus in a cropland

Microorganisms play central roles in the decomposition and retention of soil organic carbon (SOC), but how nutrient addition in intensively managed croplands influences microbial C metabolism remains uncertain. Here, we investigated the effects of coupled phosphorus (P) and nitrogen (N) additions on microbial respiration, growth rate, C use efficiency (CUE), and biomass turnover time in a continuously managed Zea mays cropland, by combining an 18-year field fertilization experiment with the 18O–H2O labeling approach. Results showed that adding P at 50 and 100 kg P ha−1, combined with 150 kg N ha−1, increased respiration by 109% and 50.7%, increased growth rate by 207% and 135%, and increased CUE from approximately 0.26 without P addition to around 0.33 and 0.35, respectively. Conversely, adding N at varying rates (0, 100, 150, and 250 kg N ha−1), combined with 50 kg P ha−1, generated variable responses. These findings underscore the significance of P as the primary limiting element for microbial metabolism in this system. Ecoenzyme stoichiometry analysis further revealed that P addition decreased microbial P vs. N limitation, as well as decreased relative C limitation. In total, changes in P vs. N limitation with P and N additions accounted for 39.6% of the variation in microbial respiration, and in conjunction with relative C limitation, co-explained 51.4% of variations in growth rate and 44.0% of variations in CUE. Furthermore, our investigation identified positive associations of CUE with the activities of N and P-acquiring enzymes, but not with SOC. These results demonstrate flexible responses of microbial C metabolism to long-term anthropogenic N and P additions, highlighting their dependence on soil nutrient limitation. Consequently, optimizing the P-to-N fertilization ratio to alleviate relative P and C limitations may maximize microbial C assimilation and SOC retention in agroecosystems.

Complex Models of Sequence Evolution Improve Fit, but not Gene Tree Discordance, for Tetrapod Mitogenomes.

Variation in gene tree estimates is widely observed in empirical phylogenomic data and is often assumed to be the result of biological processes. However, a recent study using tetrapod mitochondrial genomes to control for biological sources of variation due to their haploid, uniparentally inherited, and non-recombining nature found that levels of discordance among mitochondrial gene trees were comparable to those found in studies that assume only biological sources of variation. Additionally, they found that several of the models of sequence evolution chosen to infer gene trees were doing an inadequate job fitting the sequence data. These results indicated that significant amounts of gene tree discordance in empirical data may be due to poor fit of sequence evolution models, and that more complex and biologically realistic models may be needed. To test how the fit of sequence evolution models relates to gene tree discordance, we analyzed the same mitochondrial datasets as the previous study using two additional, more complex models of sequence evolution that each includes a different biologically realistic aspect of the evolutionary process: a covarion model to incorporate site-specific rate variation across lineages (heterotachy), and a partitioned model to incorporate variable evolutionary patterns by codon position. Our results show that both additional models fit the data better than the models used in the previous study, with the covarion being consistently and strongly preferred as tree size increases. However, even these more preferred models still inferred highly discordant mitochondrial gene trees, thus deepening the mystery around what we label the "Mito-Phylo Paradox" and leading us to ask whether the observed variation could, in fact, be biological in nature after all.

Implementation of a Nurse-Initiated Antibiotic Time-Out (NATO) in Childhood Cancer Patients in Central America

Abstract Background Children with cancer are at high risk for infection and frequently require antimicrobials. Antimicrobial stewardship (AMS) interventions can mitigate toxicity and development of antibiotic resistance yet the pharmacy and infectious diseases specialists who usually perform AMS are often absent in global settings. We report our experience testing a novel intervention to shift the antibiotic timeout to nurses in six pediatric oncology units in Central America. Methods The Nurse-initiated Antibiotic Timeout (NATO) is a scripted conversation between nurses and physicians to reevaluate antibiotic appropriateness after 48 to 72 hours of empiric use for febrile neutropenia. First, we performed a baseline assessment of AMS capacity using the WHO Practical Toolkit for AMS Programmes checklist. Based on these results, sites tailored a generic implementation plan emphasizing educational and documentation tools and iterative PDSA (Plan-Do, Study-Act) cycles to improve implementation and effectiveness outcomes. Results All sites collected antimicrobial use data for a minimum of two months. Four sites then piloted NATO, producing change ideas, including changes to documentation tools, antimicrobial decision categories, communication processes, and times. From August 2022 – October 2023, NATO was performed in 53.4% of febrile neutropenia episodes in the three sites reporting data. Sites had substantial NATO performance rate variation from month to month. Sites reported changes in antimicrobial therapy in 47% of episodes after a 6-month period (Figure 1). Conclusion The difference in performance rate of NATO underscores the importance of real-time reporting to adjust AMS implementation strategies. The change ideas developed by each site differed, however, core tools emerged, which will support AMS in other global settings. Next steps include comparing antimicrobial use pre- and post-intervention and determining a sustainability and scalability plan. Figure 1. Incidence of change in antibiotic therapy over time.

Morphological and geological responses of barrier estuaries to dam-opening systems

River discharge depending on the dam gate operation method is an important factor underlying changes in estuarine sedimentation dynamics, but comprehensive studies are limited by data collection constraints. The hydrological operation of Nakdong Dam, designed to prevent seawater intrusion by opening during ebb tides and heavy rains and closing during flood tides, presents an ideal setting for such investigations. This study focused on the Nakdong River Estuary (NRE), utilizing aerial photography, bathymetry data, and sedimentation rate data to determine alterations in sediment transport and deposition patterns within the two tributary estuaries. Spatial discrepancies in sedimentation patterns across the eastern and western regions of the NRE were particularly evident in the spatial variations of textural characteristics and sedimentation rates. An enhanced ebb tidal prism resulting from dam gate opening in the eastern region caused the development of erosional topography and a rough depositional environment, forming a landward migrating (transgressive) barrier island system. Conversely, the predominantly closed dam gates in the western region maintained a consistent deposition pattern due to a regular tidal prism, facilitating the formation of sedimentary topography and fine sediment deposition. Consequently, barrier islands followed a seaward building (prograding) system. Therefore, the results suggested a role of modern dam gate operation as a major sedimentation mechanism, providing valuable insights for the sustainable management of estuarine sediment environments.

Influence of bottom supporting columns and cooling rate on the surface shape characteristics of sapphire substrates

The manufacturing process of sapphire substrates involves several key steps, including epitaxy, annealing, cutting, and processing. Among these, epitaxy and annealing are particularly crucial. The temperature variances along both the longitudinal and transverse axes within the furnace during the crystallization process play a significant role in determining the crystallization rate and internal structure of sapphire crystals. Furthermore, annealing sapphire serves to alleviate internal stress, enhance crystal structure, optimize physical properties, improve optoelectronic characteristics, enhance surface quality, and increase overall yield. This step is paramount in enhancing the performance and application value of sapphire materials. In order to investigate and optimize the effects of different thermal conductivities of support columns at the base and various annealing procedures on the surface characteristics of sapphire substrates, thereby improving product quality, this study conducted research by utilizing support columns made of different materials and carefully controlling the cooling rate parameters for sapphire. The findings revealed that using graphite as the base support column for the crystal furnace can reduce both the longitudinal and transverse temperature gradients within the furnace, consequently promoting crystal growth and enhancing the quality of sapphire ingots. Additionally, sapphire chips annealed using the rapid one-step annealing program exhibited the highest average warpage and bending rate variation, reaching 2.0 μm, and the average dislocation density was half that of conventionally produced chips, at 108.89 pits/cm2.

Assessment of soil carbon dioxide efflux from contrasting land uses in a semi-arid savannah ecosystem, northeastern Ghana (West Africa)

Soil respiration (SR) emits a vast amount of atmospheric carbon dioxide (CO2) and contributes largely to the global greenhouse gas budget. The study assessed the dynamics of SR rates in the Vea catchment in northeastern Ghana, a sparsely gauged semi-arid savannah ecosystem characterized by distinct patterns of soil CO2 efflux. Through field measurements using soil chambers, the study quantified soil CO2 efflux rates in different land use types (woodland, cropland and grazeland), and assessed the influence of soil moisture, temperature, and soil organic carbon stocks on SR variability. The highest soil CO2 fluxes (12.97 ± 0.89 Mg CO2C ha−1 yr−1) were recorded in woodland, followed by grazeland (9.10 ± 0.42 Mg CO2C ha−1 yr−1) with cropland having the lowest rate (5.61 ± 0.29 Mg CO2C ha−1 yr−1). We recorded mean annual soil CO2 flux of 9.23 ± 0.53 Mg CO2C ha−1 yr−1 across the land use types and also observed significant seasonal and spatial variations in SR rates. The highest SR rate (220 mg CO2C m−2h−1) was recorded in the wet months (Jul-Sept and Mar-May) and the lowest rate (30 mg CO2C m−2h−1) in the dry months (Nov-Jan). For the wet season, the mean weekly soil CO2 fluxes ranged between 140 and 160 mg CO2C m−2 hr−1 as opposed to 60–75 mg CO2C m−2 hr−1 for the dry season. Seasonal and spatial variations in SR rates were largely driven by land use type, soil moisture and the interaction of soil temperature and moisture. The results underscore the importance of understanding the emission patterns from various land uses in West African savanna ecosystems to harnessing their potential for climate change mitigation.