Variation In Area Research Articles

Left-right difference in acetabular articular cartilage surface area and the quantification of acetabular fractures.

X-ray computer tomography scans were carried out on 11 female and 9 male dry bony pelvises. A 512 x 512 image matrix was used with a slice thickness and separation of 2 mm. Images were transferred onto a computer and the articular cartilage marked on each relevant image. The points were connected to form a triangle mesh and the total articular cartilage area calculated by summing the area of each triangle. There was a highly significant difference (p < 0.001) between the male and female acetabular areas, 25.4 ± 2.7 cm2 and 19.5 ± 2.0 cm2, respectively. The mean left-right difference was 0.2 ± 0.9 cm2 for males and-0.2 ± 0.47 cm2 for females. When the sign of the differences are removed, the mean and standard deviations of the differences is 0.5 ± 0.46 cm2 (2.3% ± 1.8%) for males and females, 0.66 ± 0.61 cm2 for males and 0.4 ± 0.27 cm2 for females. Each articular surface was outlined twice in order to assess the repeatability of the technique. The left-right variation in articular surface area was found to be similar to the variation in repeatability, suggesting that if any left-right difference does exist it is too small to be reliably detected by this technique. This enables the area of articular cartilage of the fragments of a fractured acetabulum to be compared directly with surface area of the contralateral intact acetabulum. Acetabular fractures can therefore be quantified by measurement of the articular surface area of the fracture components. Comparison with the clinical results will enable surface area to be developed as a prognostic factor in the management of acetabular fractures.

Experimental simulation of friction and wear between carbon fiber tow and heddle eye under periodic tension during the 3D weaving process

AbstractWeaving is the predominant technology for fabricating carbon fiber composite preforms. Carbon fibers are subjected to various forms of reciprocating friction in the weaving process. Especially, the friction between carbon tow and heddle eyes is difficult to describe due to the complex conditions of variable tension. In this study, a novel experimental simulator was developed to characterize the friction behavior between warp yarn and heddle eye under periodic tension variation. The friction force (Ff) and coefficient of friction (COF) under variable tension conditions were tested. To investigate the variation of real contact area between carbon tow and heddle eyes under variable tension conditions, a silicon‐film indentation method was developed, and the effect of pre‐tension on carbon tow was obtained by combining three‐dimensional micro surface morphology and Hertz analysis methods. The results indicated that both the COF and Ff decreased with increasing pre‐tension. 3D morphology analysis suggested that the tow contact area reached its maximum when the pre‐tension was 1.2 N. In the Hertzian calculation of the actual contact area, the change of the contact area and the pre‐tension was generated by taking into account the evolving contact length, which differed from the measured friction force value by a constant factor.Highlights A variable tension device was designed and developed. The friction between carbon tow and heddle eye was simulated under variable tension. The Ff and COF under different pre‐tensions were tested. A silicon‐film indentation method was proposed. The relationship between contact area and friction was studied.

Numerical study on the vehicle exhaust dispersion in a curved tunnel: Effects of the tunnel radius and tilt angle of jet fan

In the present work, computational fluid dynamics (CFD) was used to study the dispersion behaviours of vehicle exhaust, including the CO and PM in a curved tunnel with a consideration of the coupling effects of tunnel radius and tilt angle of jet fan. The simulation results showed the variations in the high-speed jet area in the tunnel under different tunnel radii and tilt angles of jet fan. For the pollutant diffusion, concentrations of CO and PM were shown to be inversely proportional to the tilt angle of jet fan and tunnel radius. In the vertical direction, the PM concentration was not always decreased with the increase in the altitude, which is different from distribution of CO concentration. In the horizontal direction, CO was mainly distributed at 20 – 60 m downstream from the fan, while PM accumulation covered the entire downstream of the tunnel. A close relationship between the distribution of pollutant concentration and vortex structures was found. The present work could contribute to knowledge for reducing the energy consumption of jet fans and the pollutant concentration in the curved tunnel and would provide significant guidance for the future design of curved road tunnels.

Effect of particle impact on spatial and temporal erosion characteristics of turboshaft engine compressor

When turboshaft engines operate in dusty environments, particulate matter erodes the compressor blades, which may leads to structural damage and presents a severe threat to the operational reliability and safety of helicopters. The aim of this study is to determine the erosion characteristics of compressor blades and how it changes with time. Particle velocimetry and erosive experiments were conducted to obtain the SiO2 particle velocity and the erosion rate of the Ti-6Al-4V titanium alloy. Based on the measured data, the parameters of the Tabakoff erosion model have been refined, which is critical for establishing a transient erosion model for the 1.5-stage compressor of a turboshaft engine that accounts for the effect of particle erosion time. Simulation results show that the motion behaviour of particles exhibits changing patterns at different time intervals, which leads to variations in the erosion area and erosion rate of the compressor. The erosion area and rate on blades increase nonlinearly with time. In some locations, when erosion time increases, the erosion area and erosion rate also increase. While, in other locations, the erosion area and erosion rate hardly change with time. The maximum erosion rates increased by 27.3%, 28.6%, and 87.2% for the guide blades, 42.9%, 69.6%, and 84.0% for the rotor blades, and 69.0%, 103.6%, and 142.8% for the stator blades at 0.50s, 0.75s, and 1.00s, respectively, in comparison to 0.25s.

Establishing the Hydrological Controls on Water Surface Area Variations in Oxbow Lakes

ABSTRACTOxbow lakes are iconic fluvial landforms found in the floodplains of meandering rivers around the world. Their formation is associated with meander cutoff, a process that excises sections of river channel to optimise the downstream transmission of water and sediment. Overbank floods and conveyance through tie channels maintain some hydrological connectivity, but lakes are generally considered to passively infill until they are terrestrialised. Here, a suite of 64 lakes across two meandering rivers in the Bolivian Amazon Basin are used to demonstrate the hydrological dynamism of oxbow lakes by quantifying interannual variations in lake water surface area (WSA), using the modified Normalised Difference Water Index (mNDWI) on an archive of Landsat images, and evaluating the mechanisms controlling these changes using remotely sensed rainfall data and geospatial analysis. The majority of lakes (75%) decreased in size over the study period, while 25% increased in size. The results suggest that WSA variations are controlled by proximity to the active channel, with the magnitude of these variations being set by mechanisms of connectivity. Lakes connected by tie channels experienced WSA changes up to 3.9 times larger than lakes with no visible connection mechanisms. Incursion lakes displayed similar WSA changes to those with tie channels, while isolated lakes were found furthest from the mainstem and had the smallest range of WSAs. Chute lakes experienced a wider range of WSA change (−95% to +281%) and were more strongly controlled by mainstem proximity than neck lakes. Connectivity between the river and oxbow lakes is essential for governing lake hydrodynamics, and tie channels provide the critical conduit by which water can be transmitted deep into the floodplain.

Analysis of the dependence of the observed urban air pollution extremes in the vicinity of coal fuelled power plants on combined effects of anthropogenic and meteorological drivers

In this paper we assessed effects of changes of meteorological drivers, taken from datasets of observational records and modelling outputs, and human-made pollution, derived from records of energy production, on the mainly wintertime extreme observed values of urban particulate matter (PM) concentrations in the relative vicinity of coal fuelled thermoelectric power plants (TPPs) in Montenegro and Serbia. We used wavelet transform analysis, together with the dependency analysis and analysis of averages of climatic conditions, to study temporal dynamics of urban air pollution extremes in the vicinity of TPPs, the coincidence of their changes with observed levels of SO2 and NO2 concentrations in the air, and dependence of PM changes on several possible meteorological and anthropogenic drivers. We found that PM variations in urban areas are most probably caused by PM-SO2/NO2 coincidences that appear after a 2- to 3-hour time lags needed for transformation of SO2/NO2 TPP emissions into PM particles, if pollution is caused by TPP emissions alone. When other causes of PM variations than the TPP production exist, we found that PM-SO2/NO2 correlations appear at time ranges from several hours to several days. In our analysis only the changes in the planetary boundary layer height (PBLH) coincided with the drive to extremes in PM values, at PBLH levels lower than 300m. Following these findings, we suggested that PM extremes in our sample could be viewed as preconditioned compound events, where TPP and urban heating emissions provide preconditions for PM extremes and PBLH serves as a major meteorological driver to such events.

Genotype and corticosteroid treatment are distinctively associated with gray matter characteristics in patients with Duchenne muscular dystrophy

This study investigated if structural variation in specific gray matter areas is associated with corticosteroid treatment or genotype, and if cerebral morphological variations are related to neuropsychological and behavioral outcomes.The CAT12 toolbox in SPM was used for MRI segmentations, assessing subcortical structures, cortical thickness, gyrification, and sulci depths for DMD patients (n=40; 9-18 years) and age-matched controls (n=40). Comparisons were made between DMD vs. controls, daily vs. intermittent corticosteroid treatment (n=20 each), and Dp140+ vs. Dp140- gene mutations (n=15 vs. 25). MANCOVA, CAT12 3D statistics and Pearson correlations were conducted.DMD patients showed differences in volumes of distinct subcortical structures, left hemisphere cortical thickness, and gyrification in multiple brain areas compared with healthy controls. The daily treated DMD group exhibited differences in subcortical volumes and different patterns of cortical thickness, sulci depth, and gyrification compared to the intermittent treated DMD group. DMD Dp140+ patients displayed altered gyrification and sulci depth compared to DMD Dp140- patients. Finally, we found correlations between neurobehavioral outcomes and brain areas that showed differences in cortical morphology associated with corticosteroid treatment.Both genotype and corticosteroid treatment are associated with variations in subcortical volumes and cortical morphology, albeit in different ways. Corticosteroid treatment appears to have a more profound association with differences in gray matter characteristics of brain regions that are associated with functional outcomes.

The fluctuation characteristics of typical lakes in arid areas

Study regionThree typical lakes in Xinjiang, Ulungur Lake is a fractured lake, located in the north of the Junggar Basin; China's largest inland freshwater throughput lake named Bosten Lake; known for Barkol Lake’s salt content, it is also a closed inland lake. Study focusThe study aims to investigate and contrast the spatio-temporal variation characteristics of three lake types in Xinjiang and to evaluate the accuracy of four water body indices: NDWI, MNDWI, AWEI, and MAWEI. These indices reflect water body information by calculating differences in reflectivity. The research analyzes spatial and temporal variations of these typical Xinjiang lakes from 2001 to 2022 and explores the relationship between meteorological elements and lake regulation. New hydrological insights for the regionThe study examined the relationship between typical Xinjiang lakes and meteorological elements using wavelet coherence analysis and cross wavelet transform. The findings indicate that: 1) Among the three lakes, Ulungur Lake's area variation is most directly influenced by its average air temperature, evaporation, and precipitation. 2) In the semi-arid region, temperature significantly impacts the fluctuations of Bosten and Ulungur Lakes. Temperature affects Bosten Lake the most, accounting for 55.53 %, while Ulungur Lake is also primarily affected by temperature, accounting for 58.71 %. Barkol Lake is mostly influenced by precipitation, which accounts for 35.95 %. 3) Temporally, Bosten Lake exhibits the largest area change range, whereas Ulungur Lake shows the smallest. Spatially, Barkol Lake experiences the most significant changes, and Bosten Lake undergoes the least. This suggests that ERA5 data can be utilized for regional meteorological and hydrological trend studies, and the Google Earth Engine (GEE) platform's long-term water change monitoring capabilities may support sustainable development management of inland lakes.

Assessing road construction effects on turbidity in adjacent water bodies using Sentinel-1 and Sentinel-2

Road construction significantly affects water resources by introducing contaminants, fragmenting habitats, and degrading water quality. This study examines the use of Remote Sensing (RS) data of Sentinel-1 (S1) and Senitnel-2 (S2) in Google Earth Engine (GEE) to do spatio-temporal analysis of turbidity in adjacent water bodies during the construction and operation of the E18 Arendal-Tvedestrand highway in southeastern Norway from 2017 to 2021. S1 radiometric data helped delineate water extents, while S2-Top of Atmosphere (TOA) multispectral data, corrected using the Modified Atmospheric correction for INland waters (MAIN), used to estimate turbidity levels. To ensure a comprehensive time series of RS data, we utilized S2-TOA data corrected with the MAIN algorithm rather than S2-Bottom Of Atmosphere (BOA) data. We validated the MAIN algorithm's accuracy against GLORIA (Global Observatory of Lake Responses to Interventions and Drivers) observations of surface water reflectance in lakes, globally. Subsequently, the corrected S2 data is used to calculate turbidity using the Novoa and Nechad retrieval algorithms and compared with GLORIA turbidity observations. Findings indicate that the MAIN algorithm adequately estimates water-leaving surface reflectance (Pearson correlation > 0.7 for wavelengths between 490 and 705 nm) and turbidity (Pearson correlation > 0.6 for both algorithms), determining Nechad as the more effective algorithm. In this regard, we used S2 corrected images with MIAN to estimate turbidity in the study area and evaluated with local gauge data and observational reports. Results indicate that the proposed framework effectively captures trends and patterns of turbidity variation in the study area. Findings verify that road construction can increase turbidity in adjacent water bodies and emphasis the employing RS data in cloud platforms like GEE can provide insights for effective long-term water quality management strategies during construction and operation phases.

Unveiling the future: A simulation and analysis of hydrogen production using 1kW electrolyzer with MATLAB approach

This research concentrates on optimizing hydrogen production via a 1kW electrolyzer powered by renewable solar energy, specifically targeting efficiency enhancement through adjusting membrane area. The rising global demand for clean energy solutions has positioned hydrogen as a pivotal element in the shift toward sustainable energy systems. Nonetheless, the efficacy of hydrogen generation via electrolysis continues to pose a challenge, particularly at reduced scales. This research involved the creation of a comprehensive simulation model utilizing MATLAB Simulink to investigate the impact of membrane area variations on hydrogen production and overall system efficiency. The simulation results indicate that optimizing the membrane area can substantially enhance hydrogen production rates. The system was capable of producing up to 2.5 kg/h of hydrogen, signifying a substantial enhancement over traditional methods. Moreover, incorporating solar energy as the principal power source diminishes environmental repercussions while guaranteeing a sustainable and clean approach to hydrogen production. This research introduces an innovative method for optimizing small-scale electrolyzers, offering insights applicable to industrial hydrogen production and the integration of renewable energy. The findings facilitate the advancement of sustainable hydrogen production technologies, consistent with international initiatives to diminish dependence on fossil fuels.

Features of gas chromatographic analysis of thermally unstable compounds

Confirming the stability of analytes during gas chromatographic (GC) analysis is an important criterion, especially for previously uncharacterized compounds. However, the variations of absolute peak areas at different injector temperatures usually do not allow us to reveal the thermal instability of analytes during GC analysis. Such variations may be caused by peak area known discrimination typical for using capillary columns, especially at low split injection. The thermal instability can be revealed only when using relative peak areas.The dependences of the relative peak areas of unstable analytes on the injector temperature (descending), as well as similar dependences for products of their decomposition (ascending), are characterized by the existence of two limits. Low-temperature limits correspond to the initial quantities of unstable analytes, and high-temperature limits, to their complete transformations. Such dependences can be approximated with an equation of logistic regression (synonymous: sigmoid or Boltzmann approximation).The relationships and features of gas chromatographic analysis of thermally unstable compounds are considered with products of free-radical isopropylbenzene (cumene) chlorination and with solutions of ethyl diazoacetate in different solvents as examples. The major cumene chlorination product, (1-chloro-1-methylethyl)benzene, undergoes dehydrochlorination at injector temperatures above 200 °С to form a single product, α-methylstyrene. The analysis of the ethyl diazoacetate solutions is accompanied by the formation of ethyl alkoxyacetates, products of the insertion of intermediate ethoxycarbonylcarbene into OH bonds of alcohols, if they are used as solvents. Comparing the temperatures of half-conversion of the initial ester, T(50 %), and half-formation of the products shows that they are equal to each other. This confirms both the process mechanism and the correctness of the data approximation.

2-D CFD modeling of gasification of a large biomass char particle in CO2 environment

There is a dearth in the literature of simple but robust models for gasification of large biomass particles that can address all important aspects of the reaction. A transient two-dimensional single-particle model of biomass gasification in the CO2 environment was developed in this work that incorporates chemical kinetics and heat transfer resistances, mass transfer inside the particle and boundary layer, non-equimolar counter diffusion including Knudsen diffusion, spatiotemporal variation in specific char surface area and thermophysical properties. The model was validated extensively with experimental results. Detailed simulation was carried out at reactor temperatures of 923–1123 K) using COMSOL Multiphysics software for two biomass samples – casuarina and acacia. Simulated conversion, reaction rate, temperature and gas composition profiles revealed that the reactions initially followed a shrinking core model, shifting subsequently to a shrinking reactive core model. Sensitivity analysis identified the sensitivities of process parameters as: reactor temperature > particle diameter (constant length) > initial specific char surface area > porosity > pore parameter > particle diameter (constant volume). Casuarina was found to be a more reactive and better-suited biomass than acacia for gasification applications. The work has furnished important guidelines for selecting suitable biomass type and process parameters to design an appropriate gasifier for industrial use.

Land use and land cover changes in Notwane watershed, Botswana, using extreme gradient boost (XGBoost) machine learning algorithm

ABSTRACT Botswana’s Notwane watershed is crucial for supplying water to Gaborone and surrounding areas. However, urbanization and climate variability threaten its water resources. Land Use and Land Cover (LULC) changes contribute to climate variability, impacting food security, water supply, and weakening rural economies and socio-cultural structures. This study employs geospatial techniques to model LULC changes and inform sustainable environmental management. This study utilized Extreme Gradient Boost (XGBoost), Support Vector Machine (SVM), and Random Forest (RF) algorithms to classify multi-temporal Landsat images from 1984 to 2022. The XGBoost model achieved the highest overall accuracy of 0.81%. Results indicated a 21,239.2% increase in built-up areas between the year, while agricultural land and natural vegetation decreased significantly by 9.38%. These shifts are driven by urbanization, which heightens climate change through increased greenhouse gas emissions and reduced carbon sinks. Variations in water-covered areas were, influenced by dam construction, droughts, and cyclones. A strong correlation between built-up areas and population data highlights the impact of urban expansion. To ensure sustainable urban growth and mitigate negative effects on biodiversity, urban planners must integrate sustainable land use strategies. These findings highlight the necessity for informed decision-making to balance development with environmental sustainability in the Notwane watershed.

Temporal variation in utilisation distribution and direction distribution of dugong feeding trails in intertidal seagrass beds in Talibong Island, Thailand: an insight into dugong feeding routes

Context A better understanding of animal habitat use informs fundamental ecology and can provide underpinnings for effective management. Aims This study explored the temporal variation in feeding ground utilisation by dugongs (Dugong dugon) in two intertidal seagrass beds in Talibong Island, Thailand (Sites A and B), focusing on the distribution and direction of dugong feeding trails. Methods Drone-based aerial photography was conducted quarterly over 1 year and daily over 2 weeks to observe feeding trails and behaviour. Key results During five and seven separate photography periods over 1 year, 0.04 ± 0.01% (range: 0.03–0.06%) of Site A (200,000 m2) was covered with new feeding trails daily, while 0.35 ± 0.31% (range: 0.07–0.96%) of Site B (278,000 m2) was covered daily. This temporal variation in the feeding trail area corresponded to that in seagrass coverage. Daily observations over 2 weeks during six separate photography periods revealed a significant decrease in overlapping rates (intersection over union) of the core areas (50% kernel density estimation [KDE]) as time elapsed. The 1-year observation highlighted relatively higher overlapping rates of home ranges (95% KDE) (Site A: 0.27 ± 0.09; Site B: 0.49 ± 0.08) and low overlapping rates of core areas (Site A: 0.02 ± 0.03; Site B: 0.09 ± 0.09). The relative frequencies of the feeding trail direction remained consistent across survey seasons, and the most and least dominant directions were common across all survey seasons and sites. The circular correlation coefficient between the directions of dugong body axis and the estimated tidal current was 0.45, suggesting that feeding generally occurred in the upstream direction. The direction and spatial range of dugong feeding may be affected by temporally consistent factors. One factor that can affect the feeding direction is the tidal current. Conclusions Overall, dugongs may feed and move within seagrass beds in a temporally consistent manner, even when there are shifts in feeding hotspots. Implications This research enhances our understanding of how dugongs utilise their feeding grounds and highlights the importance of not only identifying feeding hotspots but also predicting their feeding routes by considering the direction and distribution of feeding trails.

A Rapid Quantitative Assessment Method for Liver Damage Effects of Compounds Based on Zebrafish Liver Partition Area Ratio.

Total liver area is a traditional indicator in evaluating compound liver damage with zebrafish models. However, in some experiments, compounds changed zebrafish liver morphology but total liver area showed no significant difference, indicating it is inaccurate for evaluating compound effects on zebrafish liver damage. Therefore, in this study, transgenic zebrafish Tg(l-fabp:EGFP) labeled with liver cells using green fluorescent protein was used to evaluate compound effects on liver by the liver partition area ratio. The coefficient of variation of the total liver area and the liver partition area ratio of normal zebrafish at different development stages was calculated to determine the precision and dispersion of the liver partition area ratio. Three known hepatotoxic compounds (water extract of psoralea, alcohol, and α-naphthalene isothiocyanate) were used to treat zebrafish, and liver partition area ratio was calculated and verified by liver tissue pathological sections. The Pearson correlation coefficient was used to analyze the correlation between the liver partition area ratio, total liver area, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Results showed significant difference in liver partition area ratio between hepatotoxic compound treated group and control group, and it could accurately reflect liver morphology changes. There was a strong correlation between liver partition area ratio and ALT and AST level, whereas that between total liver area and ALT and AST level was low. Therefore, the change in zebrafish liver partition area ratio can be an evaluation indicator for rapid assessment of compound effects on zebrafish liver function damage, more sensitive and accurate than total liver area.

DLP 3D printing of alumina catalyst architectures: Design, kinetics and modeling of structure effects on catalyst performance

The impact of the 3D structural design on the catalytic performance was investigated in this work. Four catalyst architectures (squared honeycomb, Schwartz P, face centered cubic and gyroid), made of alumina, were designed and printed with the Digital Light Processing (DLP) printing technology. The obtained shaped catalysts were loaded in a tubular reactor and their activities were evaluated in continuous ethanol dehydration to diethyl ether. The kinetic experiments revealed that both the conversion per unit of the reactor volume and the specific activity were highly affected by the selected design of the catalyst geometry. An advanced 1-D heterogeneous mathematical model employing geometrical features of the catalyst structures was proposed to describe the experimental data. The model included local variations of contact perimeters and cross-section areas to describe the periodic architectures. The assumption of plug flow pattern in the catalyst channels was revealed to be inadequate in predicting the structure effects, thus axial dispersion effects were included to obtain a successful and statistically significant description of the experimental observations. The proposed approach forms a solid basis to describe chemical processes operated with 3D printed catalyst structures.

Microstructural Evolution and Damage Mechanism of Water-Immersed Coal Based on Physicochemical Effects of Inorganic Minerals.

Coal seam water injection technology enables seam permeability enhancement and facilitates outburst risk reduction. This study investigated the microscale effects of water infiltration on coal and the evolution mechanisms of its mechanical properties. To this end, we systematically analyzed dynamic changes (such as mineral composition, pore structure, and mechanical performance) in coal soaked for various durations using X-ray diffraction, low-field nuclear magnetic resonance (NMR), and uniaxial compression testing. The results indicate: (1) the coal NMR T2 spectrum displays three characteristic peaks, corresponding to rapid water absorption, uniform transition, and stabilization stages of soaking traditionally divided according to peak area variation trends. (2) The coal strength decreases with progressive soaking, influenced by water content, pore volume, mineral composition, etc. Its compressive strength and elastic modulus drop by 22.4% and 19.5%, respectively, compared to the initial values. (3) The expansion of clay minerals during immersion reduces average pore size. In contrast, quartz particle displacement, pore water movement, and soluble mineral dissolution increase pore volume, reducing the overall structure strength. (4) The dominant factors driving the degradation of mechanical properties vary across immersion stages, including water content and specific mineral concentration. This work offers new insights into how hydraulic technology alters coal seams, providing theoretical support for optimizing water injection strategies in the seam.

Abstract 4140136: Aortic Valve Calcification Density Performs Better Compared to Absolute Aortic Valve Calcification in Aortic Stenosis Risk Stratification

Aortic valve calcification (AVC) scores can be used to stratify aortic stenosis (AS) severity. Current practice guidelines recommend use of absolute AVC scores without considering body surface area or aortic annulus size. We investigated whether size variation in aortic annular area should be considered in identifying optimal AVC cutoffs for patients with severe AS. This was a retrospective analysis of AS patients that underwent AVC assessment during 2018-2023. Outcomes were composite of valve intervention or all-cause mortality. AVC density was defined by dividing AVC by echo-derived left ventricular tract area. Receiver operator curve analysis determined optimal AVC density scores. Absolute AVC cutoffs of &gt;1200AU for females and &gt;2000AU for males were used to identify severe AS. The study included 749 patients (mean age 78 years, 46% female). Median CT-annulus area was larger for males compared with females (532mm 2 [Q1, Q3: 479, 582] vs. 413mm 2 [370, 458], p&lt;0.001). There was a strong association of absolute AVC with CT-annulus area for both males and females (Spearman coefficient: 0.87 and 0.83, p&lt;0.01 each) respectively (Figure 1). The optimal AVC density cutoffs for males and females were 427 and 326, respectively (accuracy 76%, sensitivity 83%, specificity 51%). Composite outcomes were better differentiated with AVC density (males: HR 2.48, 95% CI: 1.82-3.37, p&lt;0.001; females: HR 2.37 (1.71-3.28), p&lt;0.001) compared with absolute AVC scores (males: HR 1.81 (1.43-2.30), p&lt;0.001; females: HR 2.11 (1.62-2.74), p&lt;0.001) (Figure 2). AVC is strongly associated with CT-annulus area and risk stratification is improved with the use of AVC density compared with absolute AVC. This may be especially helpful in patients with extremes of annulus area sizes.

Isotopic heterogeneity in U.S. Urban water supply systems reflects climatic, environmental, and sociodemographic factors: Implications for forensic identification.

The forensic application of stable oxygen isotope data from human tissues depends on naturally occurring isotopic variation in drinking water across geographic areas. One factor which complicates interpretation of forensic data is local variability: if a wide range of drinking water values is in a small geographic region it may be difficult to identify or rule out that region as a location of origin. We examine data from community collection programs documenting tap water isotope variation within 30 cities\developed areas throughout the United States. Isotopic variation within individual developed areas ranged widely, from essentially nil to greater than 9‰ (δ18O interdecile range). Many (14/30) of the study areas exhibited multi-modal isotope distributions, even in cases where the isotopic range was very small (e.g., <2.0‰), suggesting that the use of multiple, isotopically different sources was common. Most variation was attributed to differences in the source-region altitude or degree of evaporation for different water sources, and we observe limited variation in areas where contrasts in these variables are small. Variation tended to be largest in cities across the western USA. We explored correlations between the magnitude of local isotopic variation and climatic, environmental, and socioeconomic variables. We found that higher levels of variation occurred at sites where local water resources were likely to be more isotopically heterogeneous and in lower supply, consistent with the development of supply systems in these areas that access diverse and isotopically heterogeneous water resources. We also found that variation was positively correlated with larger developed areas, suggesting that pressures related to city growth may affect the degree to which infrastructure tapping diverse water resources is developed. Collectively, our results suggest that the influence of local tap water isotope heterogeneity on the precision of forensic geolocation is systematic and somewhat predictable, information to be factored into future applications.

Factors Associated With Ocular Perfusion Measurements as Obtained With Laser Speckle Contrast Imaging.

To study the ocular and systemic factors affecting optic nerve head (ONH) perfusion data as obtained using a commercially available laser speckle flowgraphy (LSFG) device in a cohort of Caucasian subjects without ocular diseases. Also, to assess the intrasession repeatability and intersession reproducibility of ONH, macular, retinal, and choroidal perfusion. Seventy-five healthy eyes of 75 Caucasian participants underwent LSFG and spectral-domain optical coherence tomography (SD-OCT) on the same visit. Perfusion of the ONH was assessed with LSFG, and SD-OCT was used to measure peripapillary retinal nerve fiber layer thickness (RNFLT) and macular ganglion cell plus inner plexiform layer thickness (GCIPLT). The intrasession repeatability and intersession reproducibility of ONH and macular perfusion and retinal and choroidal relative flow volume (RFV) were evaluated in 20 participants measured on three different days over a 6-month period. Intrasession and intersession intraclass correlation coefficients of LSFG parameters ranged from 0.787 to 0.967 and from 0.776 to 0.935, respectively. Intersession 95% prediction intervals for the ratio of two measurements were wider for RFV indices than for ONH and macular perfusion parameters. The multiple regression analysis indicated that higher ONH perfusion was associated with younger age, female sex, smaller optic disc area, and higher RNFLT. RNFLT was an independent predictor of ONH perfusion, whereas GCIPLT was not. Each 1-µm increase in RNFLT was associated with a 0.272 arbitrary unit increase in ONH perfusion. LSFG measurements of optic disc perfusion are influenced by sex, age, and anatomical variations in optic disc area and RNFLT. Better evaluation of ocular blood flow will result in better diagnosis and treatment of various ocular diseases.