8,587 results on '"SPATIAL variation"'
Search Results
2. The role of 3D electrostatic field in modeling the electrospinning process.
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Rahman, S. M., Gautam, S., Tafreshi, H. V., and Pourdeyhimi, B.
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ELECTROSPINNING , *ELECTROSTATIC fields , *TRACKING algorithms , *SPATIAL variation , *INDUCTIVE effect , *FIBERS - Abstract
Electrospinning is a cost-effective but very intricate method of producing polymeric nanofibers at room temperature. Unfortunately however, it is extremely difficult to predict the diameter or other properties of the fibers produced via electrospinning a prior. In this paper, we present a new approach to simulate fiber formation during electrospinning. Our work builds on the mathematical framework that was originally developed by Reneker and Yarin in 2000. Our approach incorporates the 3D electrostatic field that surrounds the fiber in a Lagrangian discrete particle tracking algorithm that tracks the trajectory of the fiber in air and predicts its deposition velocity and diameter. We investigate the effects of electrostatic field spatial variation on fiber electrospinning and compare our results with those obtained using a constant electrostatic field, the traditional approach, and with experiments (conducted using polyurethane). We considered three different electrospinning configurations of single-needle-plate-collector, single-needle-drum-collector, and two-needles-drum-collector to investigate how different electrostatic fields impact fiber formation. The computational model developed in this work helps to advance the current state of the art in modeling the electrospinning process. [ABSTRACT FROM AUTHOR]
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- 2024
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3. A modeling approach to understanding OLED performance improvements arising from spatial variations in guest:host blend ratio.
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Greenberg, M., Sanderson, S., White, R. D., Vamvounis, G., Burn, P. L., and Philippa, B.
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ORGANIC light emitting diodes , *CHARGE carrier mobility , *DRIFT diffusion models , *SPATIAL variation , *MULTISCALE modeling - Abstract
Phosphorescent organic light emitting diodes (OLEDs) suffer from efficiency roll off, where device efficiency rapidly decays at higher luminance. One strategy to minimize this loss of efficiency at higher luminance is the use of non-uniform or graded guest:host blend ratios within the emissive layer. This work applies a multi-scale modeling framework to elucidate the mechanisms by which a non-uniform blend ratio can change the performance of an OLED. Mobility and exciton data are extracted from a kinetic Monte–Carlo model, which is then coupled to a drift diffusion model for fast sampling of the parameter space. The model is applied to OLEDs with uniform, linear, and stepwise graduations in the blend ratio in the emissive layer. The distribution of the guests in the film was found to affect the mobility of the charge carriers, and it was determined that having a graduated guest profile broadened the recombination zone, leading to a reduction in second order annihilation rates. That is, there was a reduction in triplet–triplet and triplet-polaron annihilation. Reducing triplet–triplet and triplet-polaron annihilation would lead to an improvement in device efficiency. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Investigation on degree of non-ergodicity and local piezoelectric properties in Na0.5Bi0.5TiO3–BiFeO3–PbTiO3 system.
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Kuruvila, Krupa Maria, Shvartsman, V. V., Hotari, M., Kiselev, D. A., and Giridharan, N. V.
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RELAXOR ferroelectrics , *PIEZORESPONSE force microscopy , *PHASE transitions , *RIETVELD refinement , *ELECTRICAL conductivity transitions , *SPATIAL variation , *PIEZOELECTRICITY , *HYSTERESIS loop - Abstract
Knowledge of the statics and dynamics of ferroelectric domains is of immense importance since they are directly correlated with macroscopic polarization and strain. For the present work, piezoresponse force microscopy (PFM) is used to afford insight into field-induced phase transitions and local switching properties of a (1–2x)Na0.5Bi0.5TiO3–xBiFeO3–xPbTiO3 system for compositions, x = 0.01, 0.03, 0.05, and 0.07. Rietveld analysis of x-ray diffraction data reveals crystallization of the compound in single and dual phases in the chosen compositions. Upon the application of a local electric field, a phase transition from relaxor to normal ferroelectric (FE) is observed for all samples. A decrease in degree of non-ergodicity is realized within this composition range, which is found by analyzing the stability of field-induced ferroelectric domains. The field-induced FE domains for lower concentrations of x are found to be irreversible and a reversible nature was found for higher values of x. In addition, spatial variations of local switching parameters are investigated with the help of switching spectroscopic-PFM and a maximum local d 33 was found for compositions having dual phases. [ABSTRACT FROM AUTHOR]
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- 2023
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5. What do we know about zooplankton occurrence and distribution in Neotropical streams? A systematic review of published studies in Brazil.
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Bomfim, Francieli F., Bonecker, Claudia C., Lansac-Tôha, Fábio Amodêo, and Michelan, Thaisa S.
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ZOOPLANKTON , *STREAM function , *SPATIAL variation - Abstract
Studies on zooplankton in lakes, ponds, and rivers have always received more attention, while zooplankton from streams remains understudied worldwide. Therefore, the role of zooplankton in neotropical stream functioning is still poorly understood. In order to remedy this situation, we aimed to answer the following questions: (1) How many papers have been published on the zooplankton from Brazilian streams? (2) In which hydrographic regions were these studies conducted? (3) Are there specific patterns of zooplankton species occurrence in neotropical streams? (4) What are the main types of studies and what are the main environmental factors influencing zooplankton in streams? In order to answer these questions, we performed a systematic review of indexed scientific papers. We indeed observed a paucity of studies on zooplankton in Brazilian streams. But despite the low number of studies (24), many species (276 taxa) were reported from seven Brazilian hydrographic regions. The species composition showed great variability within the hydrographic regions and fourteen environmental variables (physical, chemical, and spatial), which can represent environmental filters and influence dispersion processes, were related to zooplankton occurrences. These bibliographic data helped to clarify patterns in species composition and community structure of zooplankton in these streams. More studies are needed to further investigate the role of zooplankton in neotropical streams, which can help to develop conservation strategies. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Clay larvae do not accurately measure biogeographic patterns in predation.
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Rodriguez‐Campbell, Antonio, Rahn, Olivia, Chiuffo, Mariana C., and Hargreaves, Anna L.
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PREDATION , *LARVAE , *CLAY , *BIOGEOGRAPHY , *SPATIAL variation - Abstract
Aim: Spatial variation in predation can shape geographic patterns in ecology and evolution, but testing how predation varies across ecosystems is challenging as differing species compositions and defensive adaptations can mask underlying patterns. Recently, biogeography has borrowed a tool from ecology: clay prey models. But clay models have not been adequately tested for geographic comparisons, and a well‐known problem –that clay prey only appeal to a subset of potential predators– could bias detected geographic patterns whenever the relative importance of predator guilds varies among sites. Here, we test whether clay larvae accurately capture geographic differences in predation on real larvae. Location: 90° of latitude and >2000 m elevation across the Americas. Taxon: Vertebrate and invertebrate predation on 'superworms' (Zophobas larvae). Methods: Across six sites that vary dramatically in latitude, elevation, and biome, we quantified predation on live, dead, and clay larvae. We physically excluded vertebrate predators from some larvae to distinguish total predation and invertebrate‐only predation. Results: Predation on live superworms almost doubled from our high‐elevation high‐latitude site to our low‐elevation tropical site. Geographic patterns were consistent among live and dead larvae, but clay larvae missed extremely high predation at some sites and therefore mis‐measured true geographic patterns. Clay larvae did a particularly bad job at capturing geographic patterns in predation by invertebrates, although sample sizes for invertebrate predation were small. Main Conclusions: Clay larvae are inappropriate for comparing predation rates across sites. They should be abandoned for biogeographic studies and reserved for comparisons within, rather than across, predator communities. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Spatial Variation in Hydrosedimentary Characteristics of the Alaknanda River Basin in the Indian Himalayas: A Field Study.
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Arora, Naman, Kumar, Arun, and Singal, Sunil Kumar
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SPATIAL variation , *WATERSHEDS , *KURTOSIS , *SUSPENDED sediments , *PARTICLE size distribution - Abstract
The Himalayas are the source of several perennial rivers with significant hydropower potential. In the region, many hydropower projects are in operation, and many more are being built. Sediment transport in Himalayan rivers is high. The Alaknanda River basin (ARB) in the Indian Himalayas has a total hydropower potential of 4,081 MW. Only 871 MW of this capacity is being utilized; the remaining 3,210 MW still needs to be tapped. Comprehensive information on hydrosedimentary characteristics is required to design and develop hydropower projects. The present study assessed the spatial variation of the hydrosedimentary characteristics of the ARB. Suspended sediment samples were collected in polyethylene bottles from 19 locations in the ARB. Suspended sediment concentration (SSC), particle size distribution (PSD), shape, and mineral composition were evaluated for all the selected locations. There were minor variations in SSC for the sampling locations. The Pindar tributary was the main influence on SSC in the ARB. Most locations exhibited clay to very fine sand particles. A graphic test method indicated sediment with moderate sorting, coarse skewness, and leptokurtic distributions at most locations. Sorting tended to increase with increasing skewness. Kurtosis showed an increasing trend with skewness; it began decreasing after reaching a maximum value (1.5). No significant spatial variations in particle shape were observed in the ARB. Most of the sampling locations had sediments with high sphericity and slight elongation. No significant spatial variation of mineralogy was observed in the ARB. Numerous minerals were identified in the ARB. Quartz (68.78% to 79.93%) was the most dominant mineral. This dominance was confirmed by an elemental analysis, in which silicon (Si) and oxygen (O) were the most abundant elements (54.73% and 37.92%, respectively). Following a procedure outlined in an international standard, the mean shape and hardness factors for the ARB were estimated at 1.36 and 0.84, respectively. The maximum random uncertainty values for SSC, PSD, sphericity, and aspect ratio were found to be 1.46%, 0.37%, 0.64%, and 0.65%, respectively. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Spatial Variation of Industrial Land Conversion and Its Influential Factors in Urban Redevelopment in China: Case Study of Shenzhen, China.
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Chen, Ke, Lai, Yani, Tao, Li, and Lin, Yanliu
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URBAN renewal , *SPATIAL variation , *URBAN land use , *SUSTAINABLE urban development , *CHINA studies - Abstract
Redevelopment of industrial land is an essential component of urban regeneration in China, which has profound implications for promoting urban sustainable development. Therefore, quantitative evaluations of the spatial variation of industrial land transformation and its influencing factors are required. This study explores the spatial patterns of industrial land transformation using overlay analysis. Then, it establishes a multinomial logistic regression model to explore their influential factors by collecting empirical data, including of the industrial renewal projects from 2010 to 2018 in Shenzhen, China. The findings show that urban redevelopment practices have profoundly transformed industrial land use in the recent urban renewal process. Market actors implement industrial land redevelopment projects with policy guidance. These actors with diversified redevelopment goals have directly shaped the spatial outcomes of industrial land transformation. A small portion of industrial sites has been transformed into public facilities and open space as required by redevelopment policies. At the same time, the majority have been converted into residential and commercial spaces, as well as new industrial spaces for innovative industries under market orientation. Significant spatial differences in regeneration outcomes exist at the urban level. The regression results indicate that policy and planning regulations, and land ownership, are the critical factors affecting the transformation of urban industrial land into different types of land uses. A favorable plot location tends to promote the transition of industrial parcels for commercial functions, with less impact on other options. The impact of public demand is almost negligible. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Model misspecification, measurement error, and apparent supralinearity in the concentration-response relationship between PM2.5 and mortality.
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Glasgow, Garrett, Ramkrishnan, Bharat, and Smith, Anne E.
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MEASUREMENT errors , *AIR quality standards , *MORTALITY , *SPATIAL variation - Abstract
A growing number of studies have produced results that suggest the shape of the concentration-response (C-R) relationship between PM2.5 exposure and mortality is "supralinear" such that incremental risk is higher at the lowest exposure levels than at the highest exposure levels. If the C-R function is in fact supralinear, then there may be significant health benefits associated with reductions in PM2.5 below the current US National Ambient Air Quality Standards (NAAQS), as each incremental tightening of the PM2.5 NAAQS would be expected to produce ever-greater reductions in mortality risk. In this paper we undertake a series of tests with simulated cohort data to examine whether there are alternative explanations for apparent supralinearity in PM2.5 C-R functions. Our results show that a linear C-R function for PM2.5 can falsely appear to be supralinear in a statistical estimation process for a variety of reasons, such as spatial variation in the composition of total PM2.5 mass, the presence of confounders that are correlated with PM2.5 exposure, and some types of measurement error in estimates of PM2.5 exposure. To the best of our knowledge, this is the first simulation-based study to examine alternative explanations for apparent supralinearity in C-R functions. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Io's Long‐Wavelength Topography as a Probe for a Subsurface Magma Ocean.
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Gyalay, S. and Nimmo, F.
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TOPOGRAPHY , *MAGMAS , *SPATIAL variation , *ISOSTASY , *INTERNAL friction , *SEISMIC anisotropy - Abstract
We investigated how spatial variations in tidal heating affect Io's isostatic topography at long wavelengths. The long‐wavelength relief is less than the 0.3 km uncertainty in Io's global shape. Assuming Airy isostasy, degree‐2 topography <0.3 km amplitude is only possible if surface heat flux varies spatially by <19% of the mean value. This is consistent with Io's volcano distribution and is possible if tidal heat is generated within and redistributed by a convecting layer underneath the lithosphere. However, that layer would require a viscosity <1010 Pa s. A magma ocean would have low enough viscosity but would not generate enough tidal heat internally. Conversely, assuming Pratt isostasy, we found ∼0.15 km degree‐2 topography is easily achievable. If a magma ocean was present, Airy isostasy would dominate; we therefore conclude that Io is unlikely to possess a magma ocean. Plain Language Summary: As it orbits Jupiter elliptically, the difference in gravitational pull experienced by the moon Io results in tidal heating due to internal friction. Some evidence suggests this heat forms a magma ocean beneath Io's crust. If so, there would be a difference in the amount of heat generated at Io's equator versus its poles and would alter the thickness of Io's crust between the two locales. Assuming the crust has a uniform density, its thickness would be inversely proportional to the tidal heat beneath the crust, which in turn affects the difference in Io's radius at the equator versus at its poles. However, reasonable variation in tidal heating across Io would result in a greater difference in radius than is observed. The difference in observed radius is more likely if variation in tidal heat across Io affects crustal density rather than crustal thickness. Then, it is more likely that Io does not have a magma ocean. Key Points: Long‐wavelength relief implies low spatial variation in Io's tidal heating when assuming Airy isostasyTidal heat produced in a convecting aesthenosphere can reduce spatial variation in tidal heating, but requires prohibitively low viscosityIo's topography is consistent with expected tidal heating spatial variations if thermal expansion drives crustal density variations [ABSTRACT FROM AUTHOR]
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- 2024
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11. Exploring the Impact of Public Health Emergencies on Urban Vitality Using a Difference-In-Difference Model.
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Chen, Yuqiao, Li, Bozhao, Liu, Songcao, and Cai, Zhongliang
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URBAN health , *STANDARD metropolitan statistical areas , *URBAN planners , *SPATIAL variation - Abstract
Urban vitality, a multifaceted construct, is influenced by economic conditions and urban structural characteristics, and can significantly be impacted by public health emergencies. While extensive research has been conducted on urban vitality, prevailing studies often rely on singular data sources, limiting the scope for holistic assessment. Moreover, there is a conspicuous absence of longitudinal analyses on urban vitality's evolution and a dearth of quantitative causal evaluations of the effects of public health emergencies. Addressing these gaps, this study devises a comprehensive framework for evaluating urban vitality, assessing Wuhan's vitality from 2018 to 2020 across economic, social, spatial, and ecological dimensions. Utilizing a Difference-In-Difference (DID) model, the impact of public health emergencies is quantified. The findings indicate pronounced spatial variations in Wuhan's urban vitality, with a gradational decline from the city center; public health emergencies exhibit differential impacts across vitality dimensions, detrimentally affecting economic, social, and spatial aspects, while bolstering ecological vitality. Moreover, high population and high public budget revenue are identified as factors enhancing urban vitality and bolstering the city's resilience against sudden adversities. This study offers valuable insights for geographers and urban planners, contributing to the refinement of urban development strategies. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Spatial variations in the osteocyte lacuno-canalicular network density and analysis of the connectomic parameters.
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Chen, Junning, Aido, Marta, Roschger, Andreas, van Tol, Alexander, Checa, Sara, Willie, Bettina M., and Weinkamer, Richard
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SPATIAL variation , *BONE shafts , *BONE remodeling , *DENSITY , *BONE diseases , *LASER microscopy , *COMPACT bone - Abstract
Osteocyte lacuno-canalicular network (LCN) is comprised of micrometre-sized pores and submicrometric wide channels in bone. Accumulating evidence suggests multiple functions of this network in material transportation, mechanobiological signalling, mineral homeostasis and bone remodelling. Combining rhodamine staining and confocal laser scanning microscopy, the longitudinal cross-sections of six mouse tibiae were imaged, and the connectome of the network was quantified with a focus on the spatial heterogeneities of network density, connectivity and length of canaliculi. In-vivo loading and double calcein labelling on these tibiae allowed differentiating the newly formed bone from the pre-existing regions. The canalicular density of the murine cortical bone varied between 0.174 and 0.243 μm/μm3, and therefore is three times larger than the corresponding value for human femoral midshaft osteons. The spatial heterogeneity of the network was found distinctly more pronounced across the cortex than along the cortex. We found that in regions with a dense network, the LCN conserves its largely tree-like character, but increases the density by including shorter canaliculi. The current study on healthy mice should serve as a motivating starting point to study the connectome of genetically modified mice, including models of bone diseases and of reduced mechanoresponse. [ABSTRACT FROM AUTHOR]
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- 2024
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13. The metallicity gradients of star-forming regions store information of the assembly history of galaxies.
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Jara-Ferreira, F, Tissera, P B, Sillero, E, Rosas-Guevara, Y, Pedrosa, S E, De Rossi, M E, Theuns, T, and Bignone, L
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GALAXIES , *STAR formation , *BLACK holes , *GALACTIC evolution , *SPATIAL variation - Abstract
The variations in metallicity and spatial patterns within star-forming regions of galaxies result from diverse physical processes unfolding throughout their evolutionary history, with a particular emphasis on recent events. Analysing MaNGA and EAGLE galaxies, we discovered an additional dependence of the mass–metallicity relation (MZR) on metallicity gradients (∇(O/H)). Two regimes emerged for low- and high-stellar mass galaxies, distinctly separated at approximately M ⋆ > 109.75 |$\rm{M}_{\odot}$|. Low-mass galaxies with strong positive ∇(O/H) appear less enriched than the MZR median, while those with strong negative gradients are consistently more enriched in both simulated and observed samples. Interestingly, low-mass galaxies with strong negative ∇(O/H) exhibit high star-forming activity, regardless of stellar surface density or ∇(O/H). In contrast, a discrepancy arises for massive galaxies between MaNGA and EAGLE data sets. The latter exhibit a notable anticorrelation between specific star formation rate and stellar surface density, independent of ∇(O/H), while MaNGA galaxies show this trend mainly for strong positive ∇(O/H). Further investigation indicates that galaxies with strong negative gradients tend to host smaller central black holes in observed data sets, a trend not replicated in simulations. These findings suggest disparities in metallicity recycling and mixing history between observations and simulations, particularly in massive galaxies with varying metallicity gradients. These distinctions could contribute to a more comprehensive understanding of the underlying physics. [ABSTRACT FROM AUTHOR]
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- 2024
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14. The resolution of face perception varies systematically across the visual field.
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Morsi, Anisa Y., Goffaux, Valérie, and Greenwood, John A.
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VISUAL fields , *PERIPHERAL vision , *SELECTIVITY (Psychology) , *PERCEPTION testing , *SPATIAL variation , *VISION - Abstract
Visual abilities tend to vary predictably across the visual field–for simple low-level stimuli, visibility is better along the horizontal vs. vertical meridian and in the lower vs. upper visual field. In contrast, face perception abilities have been reported to show either distinct or entirely idiosyncratic patterns of variation in peripheral vision, suggesting a dissociation between the spatial properties of low- and higher-level vision. To assess this link more clearly, we extended methods used in low-level vision to develop an acuity test for face perception, measuring the smallest size at which facial gender can be reliably judged in peripheral vision. In 3 experiments, we show the characteristic inversion effect, with better acuity for upright faces than inverted, demonstrating the engagement of high-level face-selective processes in peripheral vision. We also observe a clear advantage for gender acuity on the horizontal vs. vertical meridian and a smaller-but-consistent lower- vs. upper-field advantage. These visual field variations match those of low-level vision, indicating that higher-level face processing abilities either inherit or actively maintain the characteristic patterns of spatial selectivity found in early vision. The commonality of these spatial variations throughout the visual hierarchy means that the location of faces in our visual field systematically influences our perception of them. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Quantitative characterization of microstructure and research on spatial variation characteristics of loess of different strata in Luochuan, Shaanxi, China.
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Chang, Yupeng and Yuan, Shaoqing
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LOESS , *SPATIAL variation , *STATISTICAL correlation , *MICROSTRUCTURE , *SEDIMENTATION & deposition - Abstract
The complete sequence of loess strata in Luochuan has become a typical section in loess strata, and is the main focus of research for many scholars studying loess. We were based on the theory of aeolian loess and established a set of quantitative index parameters for loess microstructure through our previous research, such as equivalent diameter, sphericity, morphology ratio, orientation angle Phi, orientation angle Theta, pore Eq-Radius, throat Eq-Radius and throat channelLength. Through the quantitative characterization of various index parameters of the Luochuan loess, we found that the probability density of each index parameter meets a specific distribution well, and in terms of spatial dimension, it shows that as the depth of the strata increases, the average particle size and the mode of pore Eq-Radius, throat Eq-Radius and throat channelLength generally increase, while the mode of particle morphology ratio generally decreases. In addition, loess particles in deeper strata are less prone to vertical sedimentation and tend to deposit gently or horizontally. Most particles in different strata are distributed in a northwest or southwest direction. During the formation period of strata, the main cause for spatial differences is the material carrying force. We conducted a statistical analysis on the correlation between the macroscopic physical properties of loess and its microstructure index parameters. Specifically, we found a positive correlation between loess density and the average particle size and the mode of particle equivalent diameter, Additionally, we found a negative correlation between loess liquid limit and plastic limit, and the mode of particle morphology ratio. Furthermore, there was a negative correlation between permeability coefficient and the mode of pore Eq-Radius, throat Eq-Radius, and throat channelLength. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Taxonomic distinctness and diversity patterns of a polychaete (Annelida) community on the continental shelf of the Southern Gulf of Mexico.
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Quiroz-Martínez, Benjamín, Hernández-Alcántara, Pablo, Salas de León, David Alberto, Solís-Weiss, Vivianne, Monreal Gómez, María Adela, and Álvarez Sánchez, León Felipe
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POLYCHAETA , *CONTINENTAL shelf , *ANNELIDA , *SPATIAL variation , *MULTIVARIATE analysis , *SPECIES distribution - Abstract
The spatial patterns of taxonomic diversity of annelid polychaete species from the continental shelf in the Southern Gulf of Mexico were examined in this study. We used taxonomic distinctness and its spatial variations to explore the diversity patterns and how they change between Southern Gulf of Mexico regions. In addition, using taxonomic distinctness as a dissimilarity measure and Ward's Clustering, we characterized three distinct faunal assemblages. We also investigated patterns of richness, taxonomic distinctness, and distance decay of similarity between sampling stations as a ß-diversity measure. Finally, we examined the spatial relationships between polychaete assemblages and environmental variables to test the relative importance of spatial and environmental components in annelid polychaete community structure from the Southern Gulf of Mexico. We used a combination of eigenvector-based multivariate analyses (dbMEMs) and distance-based redundancy analysis (dbRDA) to quantify the relative importance of these explanatory variables on the spatial variations of taxonomic distinctness. The significance level of spatial and environmental components to the distribution of polychaete species showed that the combined effect of spatial processes and sediment characteristics explained a higher percentage of the variance than those parameters could alone. [ABSTRACT FROM AUTHOR]
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- 2024
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17. Spatiotemporal Characteristics and Rainfall Thresholds of Geological Landslide Disasters in ASEAN Countries.
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Lu, Weiping, Xiao, Zhixiang, Chen, Yuhang, Sun, Jingwen, and Chen, Feisheng
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LANDSLIDES , *RAINFALL , *NATURAL disaster warning systems , *DISASTERS , *SPATIAL variation , *DATABASES , *DEATH rate - Abstract
Drawing upon a comprehensive global database of landslides and utilizing high-resolution IMERG satellite precipitation data, this study investigates the spatial and temporal variations of landslide occurrences across the member states of the Association of Southeast Asian Nations (ASEAN). This study constructs a region-specific, graded warning system by formulating an average effective intensity–duration (I–D) rainfall threshold curve for each ASEAN member. Examination of 1747 landslide events spanning from 2006 to 2018 illustrates a significant association between the frequency of landslides in ASEAN regions and the latitudinal movement of local precipitation bands. Incidences of landslides hit their lowest in March and April, while a surge is observed from October to January, correlating with the highest mortality rates. Geographical hotspots for landslide activity, characterized by substantial annual rainfall and constrained landmasses, include the Philippine archipelago, Indonesia's Java Island, and the Malay Peninsula, each experiencing an average of over 2.5 landslides annually. Fatalities accompany approximately 41.4% of ASEAN landslide events, with the Philippines and Indonesia registering the most substantial numbers. Myanmar stands out for the proportion of large-scale landslide incidents, with an average casualty rate of 10.89 deaths per landslide, significantly surpassing other countries in the region. The I–D rainfall threshold curves indicate that the Philippines experienced the highest precipitation levels before landslide initiation, whereas Myanmar has the threshold set at a considerably lower level. [ABSTRACT FROM AUTHOR]
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- 2024
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18. Visualising Daily PM10 Pollution in an Open-Cut Mining Valley of New South Wales, Australia—Part I: Identification of Spatial and Temporal Variation Patterns.
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Jiang, Ningbo, Riley, Matthew L., Azzi, Merched, Puppala, Praveen, Duc, Hiep Nguyen, and Di Virgilio, Giovanni
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SPATIAL variation , *COAL reserves , *POLLUTION , *PRINCIPAL components analysis , *WAVELETS (Mathematics) , *STRIP mining - Abstract
The Upper Hunter Valley is a major coal mining area containing approximately 40% of the currently identified total coal reserves in New South Wales (NSW), Australia. Due to the ongoing increase in mining activities, PM10 (airborne particles with an aerodynamic diameter of less than 10 micrometres) pollution has become a major air quality concern in local communities. This paper summarises the spatial and temporal variability modes of PM10 pollution in the region, based on long-term multi-site monitoring data and the application of the rotated principal component analysis (RPCA) and wavelet analysis techniques. RPCA identified two distinct air quality clusters/subregions in the valley: one in the west/northwest and the other in the southeast. Wavelet analysis revealed the annual cycle to be the most persistent temporal mode of PM10 variability in both subregions, with intermittent signals also observed at time scales of around 120, 30~90, and under 30 days. How these variation modes are related to the effects of local PM10 emissions and the influence of meteorology at different time scales deserves further attention in future work. The findings will be used in air quality reporting and forecasting in NSW. The methodology and results can also be useful for air quality research in similar regions elsewhere. [ABSTRACT FROM AUTHOR]
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- 2024
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19. Relation between the relative abundance and collapse of Aphanizomenon flos-aquae and microbial antagonism in Upper Klamath Lake, Oregon.
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Underwood, Jennifer C, Hall, Natalie C, Mumford, Adam C, Harvey, Ronald W, Bliznik, Paul A, and Jeanis, Kaitlyn M
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APHANIZOMENON , *ENDANGERED ecosystems , *LAKES , *SPATIAL variation , *MICROCYSTIS , *PHOTOSYNTHETIC bacteria , *FLAVOBACTERIUM , *ECOSYSTEMS - Abstract
Aphanizomenon flos-aquae (AFA) is the dominant filamentous cyanobacterium that develops into blooms in Upper Klamath Lake, Oregon, each year. During AFA bloom and collapse, ecosystem conditions for endangered Lost River and shortnose suckers deteriorate, thus motivating the need to identify processes that limit AFA abundance and decline. Here, we investigate the relations between AFA and other members of the microbial community (photosynthetic and nonphotosynthetic bacteria and archaea), how those relations impact abundance and collapse of AFA, and the types of microbial conditions that suppress AFA. We found significant spatial variation in AFA relative abundance during the 2016 bloom period using 16S rRNA sequencing. The Pelican Marina site had the lowest AFA relative abundance, and this was coincident with increased relative abundance of Candidatus Sericytochromatia, Flavobacterium , and Rheinheimera , some of which are known AFA antagonists. The AFA collapse coincided with phosphorus limitation relative to nitrogen and the increased relative abundance of Cyanobium and Candidatus Sericytochromatia, which outcompete AFA when dissolved inorganic nitrogen is available. The data collected in this study indicate the importance of dissolved inorganic nitrogen combined with microbial community structure in suppressing AFA abundance. [ABSTRACT FROM AUTHOR]
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- 2024
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20. Timing of egg-laying in relation to a female's social environment in European starlings.
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Leonard, Kathryn M and Williams, Tony D
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STURNUS vulgaris , *SOCIAL context , *SOCIAL cues , *SPATIAL variation , *SOCIAL factors , *EGGS , *FEMALES - Abstract
It is widely assumed that female birds use nonphotic supplemental cues, including social factors, to fine-tune timing of egg-laying to local conditions, but our knowledge of the nature of these social cues and how they operate remains limited. We analyzed the relationship between a female's social environment (nearest neighbor distances, residency, female -and- network familiarity, synchrony) and variation in timing of egg-laying in European starlings (Sturnus vulgaris) using individual, residual laying date (controlling for annual variation) and temperature-independent residual laying date (accounting for the effect of ambient temperature on laying date). Female social environment varied systematically with overall spatial distribution of nest-boxes (linear vs clumped boxes) but this was not associated with spatial variation in laying date or temperature-independent residual laying date. We found no evidence for any relationships between individual variation in social environment and individual, residual laying date and only weak evidence for any association with individual, temperature-independent residual laying date. The latter was associated with (1) nearest neighbor distances in the linear habitat, with females nesting closer to neighbors laying earlier than predicted by temperature, but not in the two clumped habitats, and (2) neighbor familiarity: females with an intermediate number of returning females (3/8) laid closest to the predicted date. Finally, despite the fact that synchrony was not associated with other social environment metrics, females with lower laying synchrony among neighbors laid earlier than predicted by temperature. This suggests that some components of the female-female social environment could act as supplemental cues for timing of egg-laying. [ABSTRACT FROM AUTHOR]
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- 2024
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21. Evolution and Built-Up Age Dependency of Urban Thermal Environment.
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Li, Yuanyuan, Liu, Shuguang, Liu, Maochou, Guo, Rui, Shi, Yi, Peng, Xi, and Feng, Shuailong
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URBAN heat islands , *LAND surface temperature , *SURFACE of the earth , *METROPOLIS , *SPATIAL variation - Abstract
The urban heat island (UHI) represents an anthropogenic modification to the earth's surface, and its relationship with urban development, built-up age dependency in particular, is poorly understood. We integrated global artificial impervious areas to analyze the impacts of built-up age and urban development intensity (UDI) on land surface temperatures (LSTs) in Hefei, the capital of Anhui Province of China, from 2000 to 2019. A key finding was that the built-up areas with different built-up ages were strongly associated with LST, and this relationship does not change significantly over time, suggesting temporal stability of spatial patterns of LSTs. This finding puts forward a challenge to the application of the classic concept of space-for-time in LST studies because the premise of space-for-time is that spatial and temporal variation are equivalent. This result reveals the vital importance of annual development activities on the urban thermal environment. Another highlighted result was LST sensitivity to UDI, an effective measure of the impact of urbanization on LST, which increased significantly from 0.255 °C per 10% UDI to 0.818 °C per 10% UDI. The more than doubling of LST sensitivity to UDI should be a major concern for city administration. These findings have crucial theoretical and practical significance for the regulation of LSTs and UHI. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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22. Monitoring Total Phosphorus Concentration in the Middle Reaches of the Yangtze River Using Sentinel-2 Satellites.
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Yang, Fan, Feng, Qi, Zhou, Yadong, Li, Wen, Zhang, Xiaoyang, and He, Baoyin
- Subjects
- *
PHOSPHORUS , *SPRING , *AUTUMN , *WATER quality , *SPATIAL variation , *TURBIDITY , *SUMMER - Abstract
Total phosphorus (TP, a non-optical sensitivity parameter) has become the primary pollutant in the Yangtze River, the third largest river in the world. It is strongly correlated with turbidity (an optical sensitivity parameter) in rivers. In this study, we constructed a turbidity-mediated TP retrieval model using Sentinel-2 observations and field-measured daily-scale water quality. The model was successfully applied to estimate the temporal and spatial variations of TP concentration in the middle reaches of the Yangtze River (MYR) from 2020 to 2023. Our results show: (1) the model accuracy of TP concentration retrieval with turbidity is significantly higher (R2 = 0.71, MAPE = 15.78%) than that for the model without turbidity (R2 = 0.62, MAPE = 16.38%); (2) the turbidity and TP concentration in the MYR is higher in summer and autumn than in winter and spring; and (3) the turbidity and total phosphorus (TP) concentration of the Yangtze River showed a significant increase after passing through Dongting Lake (p < 0.05). [ABSTRACT FROM AUTHOR]
- Published
- 2024
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23. Moving Object Detection in Freely Moving Camera via Global Motion Compensation and Local Spatial Information Fusion.
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Chen, Zhongyu, Zhao, Rong, Guo, Xindong, Xie, Jianbin, and Han, Xie
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OPTICAL flow , *COMPUTER vision , *IMAGE stabilization , *CAMERAS , *RANGE of motion of joints , *SPATIAL variation - Abstract
Motion object detection (MOD) with freely moving cameras is a challenging task in computer vision. To extract moving objects, most studies have focused on the difference in motion features between foreground and background, which works well for dynamic scenes with relatively regular movements and variations. However, abrupt illumination changes and occlusions often occur in real-world scenes, and the camera may also pan, tilt, rotate, and jitter, etc., resulting in local irregular variations and global discontinuities in motion features. Such complex and changing scenes bring great difficulty in detecting moving objects. To solve this problem, this paper proposes a new MOD method that effectively leverages local and global visual information for foreground/background segmentation. Specifically, on the global side, to support a wider range of camera motion, the relative inter-frame transformations are optimized to absolute transformations referenced to intermediate frames in a global form after enriching the inter-frame matching pairs. The global transformation is fine-tuned using the spatial transformer network (STN). On the local side, to address the problem of dynamic background scenes, foreground object detection is optimized by utilizing the pixel differences between the current frame and the local background model, as well as the consistency of local spatial variations. Then, the spatial information is combined using optical flow segmentation methods, enhancing the precision of the object information. The experimental results show that our method achieves a detection accuracy improvement of over 1.5% compared with the state-of-the-art methods on the datasets of CDNET2014, FBMS-59, and CBD. It demonstrates significant effectiveness in challenging scenarios such as shadows, abrupt changes in illumination, camera jitter, occlusion, and moving backgrounds. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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24. Disentangling the relative contributions of factors determining seed physical defence: A global‐scale data synthesis.
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Wu, La‐Mei, Chen, Si‐Chong, Quan, Rui‐Chang, and Wang, Bo
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SEED dormancy , *SEEDS , *PLANT growth , *PLANT species , *DATABASES , *PERIODICAL articles , *SPATIAL variation , *VARIANCES - Abstract
Physical defence investment in seeds varies greatly among plant species and is associated with many potential factors. Exploring the factors explaining the interspecific variation in physical defence has long attracted particular attention in both ecology and evolution studies. However, the relative importance of the factors has not yet been quantitatively evaluated, which may lead to the misunderstanding of the main driver generating such interspecific variation.Here, by compiling a global database of the seed coat ratio (SCR), a proxy of seed physical defence, for 1362 species, we provided the first quantification of the relative explanations of six factors that have been commonly considered to be associated with the interspecific variation in SCR: seed mass, seed desiccation response (desiccation‐sensitive vs. desiccation‐tolerant), seed dormancy (nondormant, physical dormant or other dormant types), growth form (herbaceous vs. woody), fruit type (dry vs. fleshy) and climate (19 bioclimatic variables representing temperature and precipitation). Using partial R2 calculation that can estimate the reduction in explained variance of a given factor after removing it from a full model containing all the other factors, we disentangled the relative contribution of each factor to explain variation in the SCR.Seed desiccation response was the most important factor associating with SCR variation, followed by seed dormancy, with a partial R2lik value of 9.70% and 1.41%, respectively. Plant growth form, seed mass, climate and fruit type showed little power to explain SCR variation, although they are often cited in the literature as potential factors.Our results highlight the important roles of seed desiccation response in shaping interspecific variation in the SCR. These findings provide a detailed interpretation of ecological patterns underlying the physical defence mechanisms and allocation strategies of plant seeds. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]
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- 2024
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25. Crack Evolution and Failure Mechanisms of Rock Specimens with Oblique Cylindrical Holes in Biaxial Compression Tests.
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Kun, Du, Tengfei, Niu, Yu, Sun, Jian, Zhou, Jian, Liu, Shaofeng, Wang, and Kai, Liu
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ROCK deformation , *DIGITAL image correlation , *DISCRETE element method , *COMPRESSION loads , *ACOUSTIC emission , *FAILURE mode & effects analysis , *SPATIAL variation - Abstract
Due to the angular deviation between the tunnel axis and the in-situ principal stress direction, the stress conditions of deep surrounding rocks become more notably intricate, giving rise to significant engineering geological disasters. This study aims to investigate the effect of the angle between principal stress and tunnel axis on the failure characteristics of surrounding rocks. To achieve this, a novel granite cuboid specimen featuring an oblique cylindrical hole was designed. The cylindrical hole was set at five angle levels (0°, 5°, 15°, 30°, and 45°) and two scenarios, including the rotation plane of the cylindrical hole parallel or perpendicular to the direction of the maximum principal stress σ 1 , were considered. A comprehensive investigation on the strain field around the hole and the mechanical response of the specimens was conducted through a series of biaxial compression tests, integrating acoustic emission and digital image correlation (DIC) detection, alongside the numerical simulations using discrete element method (DEM). The results revealed that the acoustic emission characteristics exhibited marginal variation as the rotation angle increased under biaxial compression. The predominant failure mode was a tension-shear failure, primarily governed by tensile cracks. The biaxial strength of the specimens exhibited a decreasing trend with the increase of horizontal rotation angle α. Conversely, the biaxial strength initially decreased, then increased, and ultimately decreased again with an increase in the vertical rotation angle β. An X-shaped high-strain band emerged around the hole when σ 1 exceeded 60% of peak stress. As the rotation angle increased, this high-strain band extended into the interior of the specimens, with only a small portion visible on their surfaces. Numerical results confirmed that the failure characteristics inside the specimens aligned with those observed in physical test results. The spatial variation of micro-cracks in different specimens was thoroughly analyzed to discern the influences of the hole rotation angle on the failure behaviors. Highlights: An innovative granite cuboid specimen featuring an oblique cylindrical hole was introduced. The strike direction effect of the cylindrical hole on the mechanical properties of granite specimens under biaxial compression was investigated. The experimental and numerical modeling approaches were employed to study the failure mode and microcrack distribution in rock specimens with an oblique cylindrical hole. [ABSTRACT FROM AUTHOR]
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- 2024
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26. Probing the Spatial Variation of Magnetic Order in Strained SrMnO3 Thin Films Using Spin Hall Magnetoresistance.
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van Rijn, Job J. L. and Banerjee, Tamalika
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MAGNETIC declination , *SPATIAL variation , *MAGNETORESISTANCE , *THIN films , *MAGNETIC insulators - Abstract
SrMnO3 (SMO) is a magnetic insulator and is predicted to exhibit a multiferroic phase upon straining. Strained films of SMO display a wide range of magnetic orders, ranging from G‐type to C‐and A‐type, indicative of competing magnetic interactions. The potential of spin Hall magnetoresistance (SMR) is exploited as an electrical probe for detecting surface magnetic order, to read surface magnetic moments in SMO and its spatial variation, by designing and positioning electrodes of different sizes on the film. The findings demonstrate antiferromagnetic domains with different magnetocrystalline anisotropies along with a ferromagnetic order, where the magnetization arises from double exchange‐mediated ferromagnetic order and canted antiferromagnetic moments. Further, from a complete analysis of the SMR, a predominance of antiferromagnetic domain sizes of 3.5 μm2 is extracted. This work enhances the applicability of SMR in unraveling the richness of correlation effects in complex oxides, as manifested by the detection of coexisting and competing ground states, and lays the foundation for the study of magnon transport for different magnetoelectric‐based computing applications. [ABSTRACT FROM AUTHOR]
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- 2024
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27. Evaluation of Hydraulic Conductivity Estimates from Various Approaches with Groundwater Flow Models.
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Sun, Dongwei, Luo, Ning, Vandenhoff, Aaron, McCall, Wesley, Zhao, Zhanfeng, Wang, Chenxi, Rudolph, David L., and Illman, Walter A.
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- *
GROUNDWATER flow , *HYDRAULIC conductivity , *MULTISENSOR data fusion , *PARAMETER estimation , *SPATIAL variation , *GRAIN size , *BOREHOLES - Abstract
Significant efforts have been expended for improved characterization of hydraulic conductivity (K) and specific storage (Ss) to better understand groundwater flow and contaminant transport processes. Conventional methods including grain size analyses (GSA), permeameter, slug, and pumping tests have been utilized extensively, while Direct Push‐based Hydraulic Profiling Tool (HPT) surveys have been developed to obtain high‐resolution K estimates. Moreover, inverse modeling approaches based on geology‐based zonations, and highly parameterized Hydraulic Tomography (HT) have also been advanced to map spatial variations of K and Ss between and beyond boreholes. While different methods are available, it is unclear which one yields K estimates that are most useful for high resolution predictions of groundwater flow. Therefore, the main objective of this study is to evaluate various K estimates at a highly heterogeneous field site obtained with three categories of characterization techniques including: (1) conventional methods (GSA, permeameter, and slug tests); (2) HPT surveys; and (3) inverse modeling based on geology‐based zonations and highly parameterized approaches. The performance of each approach is first qualitatively analyzed by comparing K estimates to site geology. Then, steady‐state and transient groundwater flow models are employed to quantitatively assess various K estimates by simulating pumping tests not used for parameter estimation. Results reveal that inverse modeling approaches yield the best drawdown predictions under both steady and transient conditions. In contrast, conventional methods and HPT surveys yield biased predictions. Based on our research, it appears that inverse modeling and data fusion are necessary steps in predicting accurate groundwater flow behavior. Article impact statement: Evaluating K from various approaches showed that inverse modeling and data fusion are necessary steps in building robust groundwater models. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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28. Spatial variation in spring arrival patterns of Afro‐Palaearctic bird migration across Europe.
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Border, Jennifer A., Boersch‐Supan, Philipp H., Pearce‐Higgins, James W., Hewson, Chris M., Howard, Christine, Stephens, Philip A., Willis, Stephen G., Houston, Alasdair I., Gargallo, Gabriel, and Baillie, Stephen R.
- Abstract
Aim Location Time Period Major Taxa Studied Methods Results Main Conclusions Geographical patterns of migrant species arrival have been little studied, despite their relevance to global change responses. Here, we quantify continent‐wide interspecific variation in spatiotemporal patterns of spring arrival of 30 common migrant bird species and relate these to species characteristics and environmental conditions.Europe.2010–2019.Birds, 30 species.Using citizen science data from EuroBirdPortal, we modelled arrival phenology for 30 Afro‐Palaearctic migrant species across Europe to extract start and duration of species arrival at a 400 km square resolution. We related inter and intraspecific variation in arrival and duration to species characteristics and temperature at the start of the growing season (green‐up).Spatial variation in start of arrival times indicates that it took, on average, 1.6 days for the leading migratory front to move northwards by 100 km (range: 0.6–2.5 days). There was a major gradient in arrival phenology, from species which arrived earlier, least synchronously, in colder temperatures and progressed slowly northwards to species which arrived later, most synchronously and in warmer temperatures and advanced quickly through Europe. The slow progress of early arrivers suggests that temperature limits their northward advance; this group included Aerial Insectivores and species wintering north of the Sahel. For the late arrivers, which included species wintering further south, seasonal resource availability in Africa may delay their arrival into Europe.We found support for the green‐wave hypothesis applying widely to migratory landbirds. Species arrival phenologies are linked to ecological differences between taxa, such as diet, and wintering location. Understanding these differences informs predictions of species' sensitivity to global change. Publishing these arrival phenologies will facilitate further research and have additional conservation benefits such as informing designation of hunting seasons. Our methods are applicable to any taxa with repeated occurrence data across large scales. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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29. The Nanling Mountains of southern China played a variable role as a barrier and refuge for birds depending upon landscape structure and timing of events.
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Wang, Zhengzhen, Zhang, Min, Zhao, Xuebing, Xie, Jiami, Peng, Yougui, Sheldon, Frederick H., and Zou, Fasheng
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BIRD refuges , *BIRD populations , *MOUNTAIN watersheds , *GENE flow , *PLANT species , *GENETIC correlations , *SPATIAL variation - Abstract
The Nanling Mountains, an important mountain range and watershed in south China, harbor a wealth of relictual plant species, and are considered a 'museum' of subtropical biodiversity. With respect to birds, however, the roles of the Nanling Mountains in impeding the dispersal of the subtropical birds and, as a result, shaping their population and community structures have received little consideration. To examine these roles, we compiled and analyzed two datasets. 1) To test the mountains' influence on gene flow, we undertook a comparative phylogeographic study comparing mitochondrial COI and Cytb DNA sequences of five sylvioid resident bird species of the mountains (Huet's fulvetta Alcippe hueti, red‐billed leiothrix Leiothrix lutea, greater necklaced laughingthrush Pterorhinus pectoralis, Indochinese yuhina Staphida torqueola and mountain bulbul Ixos mcclellandii). 2) To examine differential community development over the history of modern birds, we examined distributional data of all species of the Nanling region using public species occurrence records. For part 1), we sampled 327 individuals from 36 sites and conducted correlation analysis of genetic and geographic distances, taking into account the landscape of the mountains. We found that the mountains do not seriously impede gene flow among populations but influenced species differently. For part 2), comparative analysis of 446 species in 81 families indicated that family membership influenced the community composition of birds in Nanling region. Variation in family distributions is attributable to both environmental and evolutionary factors. Overall, we found that the Nanling Mountains are not currently a substantial barrier to gene flow among the species we studied but act as a corridor and refuge for these birds. However, analyses on higher ranked community data suggest the mountains acted as a barrier in older times, corresponding to the known diversification events in southeast Asian avifauna. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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30. A statistical framework for detection of b-value anomalies in Italy.
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Lombardi, Anna Maria
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EARTHQUAKE magnitude , *MONTE Carlo method , *DATA distribution , *MAGNITUDE estimation , *SPATIAL variation , *STATISTICAL bias - Abstract
This study presents a new robust statistical framework, in which to measure relative differences, or deviations from a hypothetical reference value, of Gutenberg–Richter b -value. Moreover, it applies this method to recent seismicity in Italy, to find possible changes of earthquake magnitude distribution in time and space. The method uses bootstrap techniques, which have no prior assumptions about the distribution of data, keeping their basic features. Excluding Central Italy, no significative b -value variation is found, revealing that the frequency–magnitude distribution exponent is substantially stable or that data are not able to reveal hidden variations. Considering the small size of examined magnitude samples, we cannot definitively decide if the higher b -values in Central Italy, consistently founded by all applied tests, have a physical origin or result from a statistical bias. In any case, they indicate short-lived excursions which have a temporary nature and, therefore, cannot be associated solely to spatial variations in tectonic framework. Both the methodological issues and the results of the application to seismicity in Italy show that a correct assessing of b -value changes requests appropriate statistics, that accurately quantify the low accuracy and precision of b -value estimation for small magnitude samples. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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31. Morphological and genetic diversity in a South American forest‐dependent bat.
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Silva, Sofia Marques, Pavan, Ana Carolina, de Souza, Samara Alves Barroso, Ferreira, Gilmax Gonçalves, Silva, José de Sousa e, and Trevelin, Leonardo C.
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BATS , *GENETIC variation , *BIOLOGICAL classification , *SPATIAL variation , *SPECIES distribution , *PHYLLOSTOMIDAE , *KARYOTYPES - Abstract
The Neotropical realm is vastly known for its richness, being the Amazon one of the main cradles of taxonomic diversity in the region. In the last decades, molecular analyses have been further increasing the number of Amazonian vertebrate species, hidden under traditional taxonomy due to morphological convergence. Bats represent an interesting example, as the number of recognized bat species is continuously expanding with the identification of numerous cryptic taxa. Studies combining different lines of evidence, such as morphometric and molecular approaches, have been playing an important role in addressing knowledge gaps on Neotropical bat diversity. Within the Phyllostomidae family, the dwarf little fruit bat Rhinophylla pumilio is a forest‐dependent species, with a disjunct distribution in the Amazonian and Atlantic forests. Moreover, different karyotypes have been recovered across the species distribution, suggesting this might be one more example of cryptic diversity. Here, we test this assumption by identifying geographic patterns of morphological and molecular variation within the species' entire range of distribution. Our results point to an overall morphological and morphometric homogeneity, except between Atlantic Forest and Amazonian specimens, with significant dissimilarity among some cranial characters. Furthermore, genetic data suggest a rapid and recent diversification, with these two lineages most likely corresponding to speciating taxa. Within the Amazonian forest, our molecular analyses also recovered four additional lineages, likely encompassing intraspecific diversity. Furthermore, studies are required to confirm the need for a taxonomic rearrangement. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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32. The effects of spatially-constrained treatment regions upon a model of wombat mange.
- Author
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Hindle, Ivy J., Forbes, Lawrence K., Walters, Stephen J., and Carver, Scott
- Abstract
The use of therapeutic agents is a critical option to manage wildlife disease, but their implementation is usually spatially constrained. We seek to expand knowledge around the effectiveness of management of environmentally-transmitted Sarcoptes scabiei on a host population, by studying the effect of a spatially constrained treatment regime on disease dynamics in the bare-nosed wombat Vombatus ursinus. A host population of wombats is modelled using a system of non-linear partial differential equations, a spatially-varying treatment regime is applied to this population and the dynamics are studied over a period of several years. Treatment could result in mite decrease within the treatment region, extending to a lesser degree outside, with significant increases in wombat population. However, the benefits of targeted treatment regions within an environment are shown to be dependent on conditions at the start (endemic vs. disease free), as well as on the locations of these special regions (centre of the wombat population or against a geographical boundary). This research demonstrates the importance of understanding the state of the environment and populations before treatment commences, the effects of re-treatment schedules within the treatment region, and the transient large-scale changes in mite numbers that can be brought about by sudden changes to the environment. It also demonstrates that, with good knowledge of the host-pathogen dynamics and the spatial terrain, it is possible to achieve substantial reduction in mite numbers within the target region, with increases in wombat numbers throughout the environment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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33. Efficient Bayesian model selection and calibration using field data for a reinforced concrete slab bridge.
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Vereecken, Eline, Slobbe, Arthur, Rózsásb, Árpád, Bottea, Wouter, Lombaertc, Geert, and Caspeele, Robby
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CONCRETE bridges , *CONCRETE slabs , *FINITE element method , *CALIBRATION , *SPATIAL variation - Abstract
In this work, a reinforced concrete slab bridge (instrumented and tested in 2018) is investigated. Based on field data, a finite element model of the bridge is calibrated. Model selection is performed both based on log evidence and posterior predictive capabilities. It is investigated if the models selected based on the log evidence also induce the most accurate posterior predictions. The influence of different assumptions on modelling the spatial distribution of the stiffness and different possible suggestions on how to include prediction errors and model bias are investigated. Comparing the conclusions based on log evidence and posterior predictions, only using the log evidence for model selection could be debated. Models performing best when considering the log evidence led to the least accurate posterior predictions, and models rejected based on the log evidence could still have good predictive capabilities. Considering the different model classes, introducing spatial variation of the stiffness leads to a posterior prediction closer to the measurements. Introducing a global model bias leads to a better match between predictions and measurements compared to not including this model bias. Even better posterior predictions are achieved if this model bias is quantified locally for the different considered datapoints. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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34. Topographical gradient of the structure and diversity of a woody plant community in a seasonally dry tropical forest in northwestern Madagascar.
- Author
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Fujimoto, Yutaro, Kaneko, Takayuki, Sato, Hiroki, Rakotomamonjy, Ando Harilalao, Razafiarison, Zo Lalaina, and Kitajima, Kaoru
- Abstract
Few studies have evaluated the structure and dynamics of forests in Madagascar with high levels of endemism. Ankarafantsika National Park holds the largest of the remaining primary dry forests in northwestern Madagascar, where most of the forests have been lost or degraded by fire and other human activities. In this primary forest, we established a 15‐ha forest dynamics monitoring plot and mapped and identified all woody stems with a diameter at breast height (DBH) ≥5 cm. The forest stand was characterized by small‐sized individuals (75% of stems with DBH <10 cm, with 99% of trees with height <15 m), encompassing 35,758 tree and 513 liana individuals belonging to 160 species in 53 families (including 20 species of lianas accounting for 1.4% of the stems). Most species‐rich families were Rubiaceae, Fabaceae, Lamiaceae, and Malvaceae, which together encompassed 43 tree species and 23% of all tree individuals. The plot was located on a hill consisting of white sand at elevations from 150 to 200 m, with a gentle slope down from southwest to northeast. Over this elevation gradient, stem density and species diversity increased with elevation, while tree height and diameter decreased. The most abundant two species, Drypetes perrieri (Putranjivaceae) and Noronhia alleizettei (Oleaceae) are evergreen, suggesting the importance of a nutrient conservation strategy. These results provide the foundational knowledge necessary for the conservation and restoration of natural semi‐deciduous dry forests that used to cover large areas in northwestern Madagascar until recently. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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35. Propagation thresholds and driving mechanism detection of karst meteorological- agricultural drought: A case study in Guizhou Province.
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Chen, Lihui, He, Zhonghua, Tan, Hongmei, Xu, Mingjin, and Gu, Xiaolin
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DROUGHT management , *DROUGHTS , *AGRICULTURE , *KARST , *AGRICULTURAL exhibitions , *SOIL moisture , *SPATIAL variation - Abstract
It is significant to systematically quantify the propagation thresholds of meteorological drought to different levels of agricultural drought in karst areas, and revealit's the propagation driving mechanisms. This can guide early warning and fine management of agricultural drought. In this study,we selected Guizhou Province as an example. The standardized precipitation evapotranspiration index (SPEI) and standardized soil moisture index (SSI) were used to characterize meteorological and agricultural drought. The run theory was used to identify, merge and eliminate drought events. The maximum correlation coefficient was used to capture the propagation time of meteorological-agricultural drought. The regression models were used to quantify the propagation intensity threshold from meteorological drought to different levels of agricultural drought. Finally, the propagation threshold driving mechanism was explored using geographical detectors. The results show that: (1) in terms of temporal variations during the past 21 years, regional meteorological drought had a shorter duration and a higher intensity than agricultural drought, Particularly, 2011 was a year of severe drought, and agricultural drought was significantly alleviated after 2014. (2) In terms of spatial variations, the "long duration area" of meteorological drought duration showed an "S" shaped distribution in the northeast, and the "short duration area" showed a point-like distribution. The overall duration of agricultural drought showed a spatial distribution of northeast to "medium-high in the northeast and low in the southwest. (3) The drought propagation time showed an alternating distribution of "valley-peak-valley-peak" from southeast to northwest. In terms of propagation intensity thresholds, light drought showed an overall spatial distribution of high in the east and low in the west. Moderate, severe, and extreme droughts showed a spatial distribution of low in the center north of southern Guizhou) and high in the borders. (4) There was a strong spatial coupling relationship between karst development intensity, altitude and meteorological-agricultural drought propagation thresholds. The interaction of different factors exhibited a two-factor enhancement and nonlinear enhancement on the propagation threshold. This indicates that synergistic effects of different factors on the propagation threshold were larger than single-factor effects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Spatial and Temporal Variation Patterns of NO 5.3 µm Infrared Radiation during Two Consecutive Auroral Disturbances.
- Author
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Wu, Fan, Dai, Congming, Chen, Shunping, Zhang, Cong, Lian, Wentao, and Wei, Heli
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AURORAS , *SPATIAL variation , *SOLAR wind , *MAGNETIC storms , *WIND speed , *DATABASES , *INFRARED radiation - Abstract
The variation in key parameters of the solar–terrestrial space during two consecutive auroral disturbances (the magnetic storm index, Dst index = −422 nT) that occurred during the 18–23 November 2003 period was analyzed in this paper, as well as the spatiotemporal characteristics of NO 5.3 μm radiation with an altitude around the location of 55°N 160°W. The altitude was divided into four regions (50–100 km, 100–150 km, 150–200 km, and 200–250 km), and it was found that the greatest amplification occurs at the altitude of 200–250 km. However, the radiance reached a maximum of 3.38 × 10−3 W/m2/sr at the altitude of 123 km during the aurora event, which was approximately 10 times higher than the usual value during "quiet periods". Based on these findings, the spatiotemporal variations in NO 5.3 μm radiance within the range of latitude 51°S–83°N and longitude of 60°W–160°W were analyzed at 120 km, revealing an asymmetry between the northern and southern hemispheres during the recovery period. Additionally, the recovery was also influenced by the superposition of a second auroral event. The data used in this study were obtained from the OMNI database and the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) infrared radiometer onboard the TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) satellite. Finally, the correlation of NO 5.3 μm radiance at 120 km with temperature, solar wind speed, auroral electrojet index (AE index), and Dst index were analyzed. It was found that only the Dst index had a good correlation with the radiance value. Furthermore, the correlation between the Dst index and radiance at different altitudes was also analyzed, and the highest correlation was found at 170 km. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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37. Patterns of Tadpole β Diversity in Temperate Montane Streams.
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Kang, Da, Sun, Zijian, Tao, Jiacheng, Huang, Yan, and Zhao, Tian
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TADPOLES , *SPATIAL variation , *AMPHIBIANS - Abstract
Simple Summary: Beta diversity is considered to be more accurate in reflecting the dynamics of community structure, as well as community assembly rules. However, many previous studies were only conducted in islands and lakes, while more attention is still needed for montane ecosystems. The main objective of the present study was to understand tadpole β diversity in temperate montane streams. The field work was conducted in 18 streams of Mount Emei, southwestern China, in 2018 and 2019. Our results indicated a high total tadpole β diversity, which was mainly contributed by a turnover process, and this pattern was shaped by both spatial and environmental factors. Understanding the spatial variation and formation mechanism of biological diversity is a hot topic in ecological studies. Comparing with α diversity, β diversity is more accurate in reflecting community dynamics. During the past decades, β diversity studies usually focused on plants, mammals, and birds. Studies of amphibian β diversity in montane ecosystems, in particular, tadpoles, are still rare. In this study, Mount Emei, located in southwestern China, was selected as the study area. We explored the tadpole β diversity in 18 streams, based on a two-year survey (2018–2019). Our results indicated a high total β diversity in tadpole assemblages, which was determined by both turnover and nestedness processes, and the dominant component was turnover. Both the total β diversity and turnover component were significantly and positively correlated with geographical, elevational, and environmental distances, but no significant relationship was detected between these and the nestedness component. Moreover, the independent contributions of river width, current velocity, and chlorophyll α were larger than that of geographical and elevational distance. Overall, tadpole β diversity was determined by both spatial and environmental factors, while the contribution of environmental factors was larger. Future studies can focus on functional and phylogenetic structures, to better understand the tadpole assembly process. [ABSTRACT FROM AUTHOR]
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- 2024
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38. Lunar South Polar Water Cycle and Water Resources: Diurnal and Spatial Variations in Surficial Hydration From Repeated Moon Mineralogy Mapper Observations.
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Lu, Yu, Wang, Wenwen, Jiao, Hengyue, Xu, Tianyi, Chen, Xuejiao, and Wu, Yunzhao
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LUNAR south pole , *HYDROLOGIC cycle , *MOON , *SPATIAL variation , *WATER supply - Abstract
The diurnal variation and distribution of lunar surficial hydration (OH/H2O) is of great significance for understanding the solar wind implantation and water cycle on the Moon. Lunar south pole is an ideal place to study the diurnal variation of surficial hydration due to the large number of repeat observations of the same region, which is very limited in mid‐ or low‐latitudes. Here we showed clear 0.5‐hr interval diurnal variation of surficial hydration at lunar south pole. The variation of hydration band depth with local time is exactly the opposite to the variation of temperature, indicating that lunar surficial hydration changes sufficiently with temperature. This relationship indicates that both the diurnal variation and hydration content are latitude dependent. Our observations support the hypothesis that the diurnal variation of hydration on the Moon is due to the formation of metastable hydroxyl. Plain Language Summary: Hydration (OH/H2O) has been found on the surface of the Moon due to the implantation of solar wind. Hydration contents in the morning and evening were observed to be higher than that at local noon. Lunar south pole is a very good place to study the diurnal variation of surficial hydration compared with other places of the Moon as there are a lot of repeat observations of the same area at different local times. We conducted a detailed investigation of surficial hydration at the lunar south pole based on repeat Moon Mineralogy Mapper near‐infrared data. We found surficial hydration at lunar south pole gradually decreases toward local noon, and then recovers to the morning level at evening. The variation trend is exactly the opposite to the temperature, indicating lunar surficial hydration changes sufficiently with instantaneous temperature. These observations provide clues for studies on the formation and evolution of volatiles on the Moon and other airless bodies. Key Points: 0.5‐hr interval diurnal variation of lunar surficial hydration was revealed at lunar south pole for the first timeLunar surficial hydration changes sufficiently with instantaneous temperatureLunar surficial hydration did not change when the Moon enters the Earth's magnetotail [ABSTRACT FROM AUTHOR]
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- 2024
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39. Spatial versus spatio-temporal approaches for studying metacommunities: a multi-taxon analysis in Mediterranean and tropical temporary ponds.
- Author
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Gálvez, Ángel, Peres-Neto, Pedro R., Castillo-Escrivà, Andreu, Bonilla, Fabián, Camacho, Antonio, García-Roger, Eduardo M., Iepure, Sanda, Miralles, Javier, Monrós, Juan S., Olmo, Carla, Picazo, Antonio, Rojo, Carmen, Rueda, Juan, Sasa, Mahmood, Segura, Mati, Armengol, Xavier, and Mesquita-Joanes, Francesc
- Abstract
Prior research on metacommunities has largely focused on snapshot surveys, often overlooking temporal dynamics. In this study, our aim was to compare the insights obtained from metacommunity analyses based on a spatial approach repeated over time, with a spatio-temporal approach that consolidates all data into a single model. We empirically assessed the influence of temporal variation in the environment and spatial connectivity on the structure of metacommunities in tropical and Mediterranean temporary ponds. Employing a standardized methodology across both regions, we surveyed multiple freshwater taxa in three time periods within the same hydrological year from multiple temporary ponds in each region. To evaluate how environmental, spatial and temporal influences vary between the two approaches, we used nonlinear variation partitioning analyses based on generalized additive models. Overall, this study underscores the importance of adopting spatio-temporal analytics to better understand the processes shaping metacommunities. While the spatial approach suggested that environmental factors had a greater influence, our spatio-temporal analysis revealed that spatial connectivity was the primary driver influencing metacommunity structure in both regions. Temporal effects were equally important as environmental effects, suggesting a significant role of ecological succession in metacommunity structure. [ABSTRACT FROM AUTHOR]
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- 2024
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40. Spatial variations and determinants of timely completion of vaccination in Ethiopia using further analysis of EDHS 2019 data: Spatial and multilevel analysis.
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Agimas, Muluken Chanie, Belew, Aysheshim Kassahun, Sisay, Mekonnen, Daniel Baffa, Lemlem, Gashaw, Moges, Yiheyis Abriham, Zufan, Ali Muhammad, Esmael, Anteneh Yigzaw, Zeamanuel, and Mengistu, Berhanu
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MULTILEVEL models , *SPATIAL variation , *VACCINATION of children , *VACCINATION , *LOGISTIC regression analysis , *DATA scrubbing - Abstract
Background: Timely vaccination is the practice of administering the vaccine within the first birthday of the child. Not vaccinating the child at the appropriate age is the cause of improper protection of diseases and can be a possible factor in death. The problem of not completing the vaccine in the scheduled period is a globally distributed problem, but especially in sub-Saharan African countries, it is a bottleneck to child health. Even if timely vaccination is crucial for reducing the impact of VPDs, there are no current national-level studies to generate conclusive and tangible evidence in Ethiopia. Objective: To assess spatial variations and determinants of timely completion of vaccination in Ethiopia using further analysis of EDHS 2019 data. Method: The secondary data analysis of a community-based cross-sectional study design was employed among 3094 participants. Stata-14 software was used for data cleaning, recording, and analysis. Arc GIS version 10.3 and Kuldorff SAT scan version 9.6 software are used for spatial and SAT scan statistics. A multilevel mixed-effect binary logistic regression analysis was used to identify the predictors of timely vaccination. The clustering effect was also evaluated by Moran's I statistics and intra class correlation. Results: The timely completion of vaccination among Ethiopian women who had a child aged 12–35 months was 19.5% (95%CI: 18.2–20.8), and the spatial distribution of timely completion of vaccinations in Ethiopia was non-randomly distributed. A statistically significant high proportion of timely completion areas were clustered in the eastern part of Amhara, the south part of Afar, Addis Ababa, and Oromia. The primary cluster was located at a 13.11 km radius in Diredawa, which was 3.68 times higher than outside the window (RR = 3.68, LLR = 68.76, p-value < 0.001). History of antenatal care follow-up (AOR = 1.63, 95% CI: 1.3–2.04), giving birth at health facilities (AOR = 1.63, 95% CI: 1.25–2.13), age ≥ 35 years (AOR = 186, 95% CI: 1.35–2.63), age 25–34 years (AOR = 1.72, 95% CI: 1.33–2.21), and being richest (AOR = 2.71, 95% CI: 1.86–3.94) were the factors contributing to the timely completion of vaccination. Conclusion: The prevalence of timely completion of vaccination was low in Ethiopia, and the spatial distribution of timely completion of vaccination in Ethiopia was non-randomly distributed across the regions. The factors associated with the timely completion of vaccinations were ANC follow-up, place of delivery, age of the participant, and wealth index. We recommend expanding facility delivery, antenatal care services, and empowering women to scale up timely vaccination in Ethiopia. [ABSTRACT FROM AUTHOR]
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- 2024
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41. Spatial analysis of PM2.5 using a Concentration Similarity Index applied to air quality sensor networks.
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Byrne, Rósín, Wenger, John C., and Hellebust, Stig
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AIR quality indexes , *SENSOR networks , *AIR quality monitoring , *RESEMBLANCE (Philosophy) , *AIR quality , *SPATIAL variation - Abstract
Air quality sensor (AQS) networks are useful for mapping PM2.5 in urban environments, but quantitative assessment of the observed spatial and temporal variation is currently under-developed. This study introduces a new metric – the Concentration Similarity Index (CSI) – to facilitate a quantitative and time-averaged comparison of the concentration‑time profiles of PM2.5 measured by each sensor within an air quality sensor network. Following development on a dataset with minimal unexplained variation and robust tests, the CSI function is ensured to represent an unbiased and fair depiction of the air quality variation within an area covered by a monitoring network. The measurement data is used to derive a CSI value for every combination of sensor pairs in the network, which can then be compared with others in the network, yielding valuable information on spatial variation in PM2.5. This new method is applied to two separate AQS networks in Dungarvan and Cork City, Ireland. Dungarvan yielded a lower mean CSI, indicating lower overall similarity between locations in the network, possibly due to the town's coastal location giving rise to higher variation within the network. In both networks, the average diurnal plots for each sensor exhibit an evening peak in PM2.5 concentration due to emissions from residential solid fuel burning, however, there is considerable variation in the size of this peak. Clustering techniques applied to the CSI matrices identify two different location types in each network; locations in central or residential areas which experience more pollution from sold fuel burning and locations on the edge of the urban areas which experience cleaner air. Furthermore, the examination of isolated data periods (January and May) indicates higher PM2.5 levels during periods of increased residential solid fuel burning act as a major driver for greater differences (lower similarity indices) between locations in both networks. Additionally, the CSI method facilitates the assessment of the representativeness of the PM2.5 measured at regulatory air quality monitoring locations with respect to population exposure, showing here that location type is more important than physical proximity in terms of similarity assessment. Applying the CSI in this manner can allow for the placement of monitoring infrastructure to be optimised. The findings of this work underscore the influence of solid fuel combustion as a local contributor to PM2.5 and the variation it can cause between the measurements at different monitoring locations in a network while also highlighting the importance of including wintertime PM data for accurate comparisons. The CSI method developed here could be a valuable tool for quantitative comparisons of air quality within a monitoring network, offering insights for further regulatory monitoring and exposure assessments. [ABSTRACT FROM AUTHOR]
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- 2024
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42. The impact of thixotropic behavior on microfluidic mixing in a staggered-herringbone mixer.
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Park, Jo Eun, Kang, Tae Gon, and Jung, Seon Yeop
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SHEAR (Mechanics) , *THIXOTROPY , *SPATIAL variation , *VISCOSITY , *FLUIDS - Abstract
This study numerically explores the influence of thixotropy on flow and mixing in a staggered-herringbone micromixer (SHM), employing a structure-kinetics model to simulate the microstructure formation and breakup in thixotropic fluids. This study represents the first of its kind to incorporate a thixotropic fluid model into microfluidic mixing in channels with patterned grooves. Specifically, we examine the effects of the destruction factor ( k d ) and the thixotropy number (Th) on microstructure, flow, and mixing in the SHM, covering extensive ranges (0.01 ≤ k d ≤ 10 and 0.01 ≤ Th ≤ 100). Higher values of k d and Th , particularly for k d > 1 and Th > 1 , lead to larger spatial variations of the structure parameter (λ) and viscosity (η), with a notable decrease in λ near the groove tops, leading to the lowest viscosity in these areas. Conversely, at the groove bottoms, where shear deformation is minimal, there is less reduction in λ , leading to increased viscosity and higher flow resistance. The viscosity variations inside the grooves impede lateral flows, adversely affecting mixing in the higher k d and Th regimes. Therefore, an in-depth understanding of the complex thixotropic behaviors, as influenced by k d and Th near the grooves, is essential for achieving effective mixing in the SHM when using thixotropic fluids. Our results suggest that lowering the channel height, for a given groove depth, slightly improves the mixing of thixotropic fluids. Further enhanced mixing is achieved by combining a reduced channel height with double-sided groove patterns. [ABSTRACT FROM AUTHOR]
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- 2024
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43. Spatial and temporal variation of the Formicidae assemblage in different forest types of the Chaco Seco ecoregion, Argentina.
- Author
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BARRIENTOS, GUALTERRO, DETTLER, ANTONELLA, and MARTINEZ, EMILIA
- Subjects
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FORESTS & forestry , *SPATIAL variation - Abstract
Ants have been widely used as bioindicators of natural and disturbed environments. In Argentine Chaco Seco, ants represent an important part of the total biodiversity and fulfil various functions in forest ecosystems. With the aim of evaluating β diversity and identifying indicator ants, surveys were carried out in three types of implanted forests: Neltuma alba (mesquite), Eucalyptus tereticornis (eucalyptus) and mixed forests without intervention for 50 years, mainly composed of Ceiba speciosa and Phoenix canariensis, located at the Fernández Experimental Station of the Catholic University of Santiago del Estero. The samplings were carried out in spring, summer and autumn, between 2019 and 2022, using pitfall traps that remained active for 24 h. The abundance and composition of Formicidae at each site and season were evaluated using the Jaccard similarity index and generalized linear mixed models. A total of 7366 individuals grouped into 28 species belonging to 6 Formicidae subfamilies were identified. Some species were present at all sites and seasons, with Solenopsis saevissima, Camponotus mus and Pheidole bergii being the most abundant in the mesquite, eucalyptus and mixed stands, respectively. In addition, three exclusive species of N. alba, two of E. tereticornis and one of the mixed stand were identified. Furthermore, it was observed that the myrmecological composition varied seasonally, mainly during autumn. These results demonstrate that due to the characteristics of each site, representative groups of ants can be found for each that could be used as indicators of each type of environment and that the temporal variation of the communities is favored by the diversification of the habitats, which offer different resources during each season of the year, increasing the turnover rate. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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44. Preventing multiple resistance above all: New insights for managing fungal adaptation.
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Ballu, Agathe, Ugazio, Claire, Duplaix, Clémentine, Noly, Alicia, Wullschleger, Juerg, Torriani, Stefano F. F., Dérédec, Anne, Carpentier, Florence, and Walker, Anne‐Sophie
- Subjects
- *
PLANT protection , *SPATIAL variation , *FOOD security , *PHYSIOLOGICAL adaptation - Abstract
Sustainable crop protection is vital for food security, yet it is under threat due to the adaptation of a diverse and evolving pathogen population. Resistance can be managed by maximising the diversity of selection pressure through dose variation and the spatial and temporal combination of active ingredients. This study explores the interplay between operational drivers for maximising the sustainability of management strategies in relation to the resistance status of fungal populations. We applied an experimental evolution approach to three artificial populations of Zymoseptoria tritici, an economically significant wheat pathogen, each differing in initial resistance status. Our findings reveal that diversified selection pressure curtails the selection of resistance in naïve populations and those with low frequencies of single resistance. Increasing the number of modes of action most effectively delays resistance development, surpassing the increase in the number of fungicides, fungicide choice based on resistance risk, and temporal variation in fungicide exposure. However, this approach favours generalism in the evolved populations. The prior presence of multiple resistant isolates and their subsequent selection in populations override the effects of diversity in management strategies, thereby invalidating any universal ranking. Therefore, the initial resistance composition must be specifically considered in sustainable resistance management to address real‐world field situations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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45. Characterization of Wildland Fuels Based on Topography and Forest Attributes in North-Central Appalachia.
- Author
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Dong, Ziyu and Williams, Roger A.
- Subjects
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OAK , *TOPOGRAPHY , *WOODY plants , *SPATIAL variation , *BEHAVIORAL research - Abstract
Forest ecosystem attributes and their spatial variation across the landscape have the potential to subsequently influence variations in fire behavior. Understanding this variation is critical to fire managers in their ability to predict fire behavior and rate of spread. However, a fine-scale description of fuel patterns and their relationship with overstory and understory attributes for north-central Appalachia is lacking due to the complicated quantification of variations in topography, forest attributes, and their interactions. To better understand the fire environment in north-central Appalachia and provide a comprehensive evaluation based on fine-scale topography, ninety-four plots were established across different aspects and slope positions within an oak–hickory forest located in southeast Ohio, USA, which historically fell within fire regime group I with a fire return interval ranging from 7 to 26 years. The data collected from these plots were analyzed by four components of the fire environment, which include the overstory, understory, shrub and herbaceous layers, surface fuels, and fuel conditions. The results reveal that fuel bed composition changed across aspects and slope position, and it is a primary factor that influences the environment where fire occurs. Specifically, the oak fuel load was highest on south-facing slopes and in upper slope positions, while maple fuel loads were similar across all aspects and slope positions. Oak and maple basal areas were the most significant factors in predicting the oak and maple fuel load, respectively. In the shrub and undergrowth layers, woody plant coverage was higher in upper slope positions compared to lower slope positions. Overstory canopy closure displayed a significant negative correlation with understory trees/ha and woody plant variables. The findings in this study can provide a better understanding of fine-scale fuel bed and vegetation characteristics, which can subsequently feed into fire behavior modeling research in north-central Appalachia based on the different characterizations of the fire environment by landscape position. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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46. Analysis of spatial and seasonal variations of Haemaphysalis longicornis population based on field survey collected under different habitats and years.
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Yoon, Sunhee, Jung, Jae‐Min, Oh, Sumin, Bae, Jongmin, Byun, Hye‐Min, Choi, Subin, Jang, Geunho, Kang, Minjoon, Kim, Eunji, Park, Jaekook, Seong, Keon Mook, Lee, Wang‐Hee, and Jung, Sunghoon
- Subjects
- *
FIELD research , *SPATIAL variation , *DECIDUOUS forests , *HABITATS , *TICK-borne diseases - Abstract
Ticks are vectors of disease‐causing pathogens and are found on domestic and wild animals; thus, they are also vectors of significant human diseases. For this reason, pre‐emptive measures to prevent tick‐borne diseases are necessary in the form of exploring their major habitats, population increase period, and factors affecting their population growth, all of which indicate the purpose of this study. In the study, a variation of Haemaphysalis longicornis, a major vector of fever‐causing conditions, was statistically analyzed to identify the spatial and climatic factors affecting the time‐dependent variations of its population. The survey occurred in different habitats (grassland, mixed forest, deciduous forest, and coniferous forest) in South Korea. In addition, we fitted a phenology model by using a probability function to find the peak occurrence time annually. As a result, the numbers of adults and nymphs were found to be related to temperature and relative humidity and their population peaked at the end of May in all habitats except deciduous forests. This study is expected to provide information on habitat types, times, and climate patterns that require attention to help control H. longicornis populations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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47. Response of Chironomids (Diptera, Chironomidae) to Environmental Factors at Different Spatial Scales.
- Author
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Rossaro, Bruno and Marziali, Laura
- Subjects
- *
SPATIAL variation , *DISCRIMINANT analysis , *CHIRONOMIDAE , *FRESHWATER habitats , *AQUATIC insects , *DIPTERA , *BENTHIC animals - Abstract
Simple Summary: Chironomids are probably the most speciose family among aquatic insects, colonizing almost all freshwater habitats. The emphasis of the present research is on: (1) taxonomic composition as the most efficient tool for describing biodiversity in natural habitats; and (2) natural habitat type as the most important factor able to explain different chironomid assemblages. This is because the habitat type summarizes a combination of different biotic and abiotic factors present at each site, determining taxa assemblages. Different spatial scales are often proposed as relevant factors for modeling community composition, but with regard to chironomids, spatial factors act only at a small scale, while environmental factors are the most important determinants for species distribution. Factors responsible for species distribution of benthic macroinvertebrates, including responses at different spatial scales, have been previously investigated. The aim of the present research was to review the most relevant factors explaining chironomid species distribution focusing on factors operating at different spatial scales, such as latitude, longitude, altitude, substrate, salinity, water temperature, current velocity, conductivity, acidity, dissolved oxygen, nutrient content etc. acting at regional levels and at a large or small water basin level. Data including chironomid species abundances from different lentic and lotic waters in Italy and other surrounding countries were analyzed using partial canonical correspondence analysis (pCCA) and multiple discriminant analysis (DISCR). Spatial analyses, including univariate Moran's I correlograms, multivariate Mantel correlograms and Moran's eigenvector maps (MEMs), were thereafter carried out. The results showed that habitat type, including different types of lotic waters (i.e., kryal, crenal, rhithral, potamal) and different lake types (i.e., littoral, sublittoral, profundal zones), is the most significant factor separating chironomid assemblages, while spatial factors act only as indirect influencers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Meteor Radar for Investigation of the MLT Region: A Review.
- Author
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Reid, Iain M.
- Subjects
- *
METEOR showers , *METEORS , *METEOROIDS , *WORLD War II , *SPATIAL variation - Abstract
This is an introductory review of modern meteor radar and its application to the measurement of the dynamical parameters of the Mesosphere Lower Thermosphere (MLT) Region within the altitude range of around 70 to 110 km, which is where most meteors are detected. We take a historical approach, following the development of meteor radar for studies of the MLT from the time of their development after the Second World War until the present. The application of the meteor radar technique is closely aligned with their ability to make contributions to Meteor Astronomy in that they can determine meteor radiants, and measure meteoroid velocities and orbits, and so these aspects are noted when required. Meteor radar capabilities now extend to measurements of temperature and density in the MLT region and show potential to be extended to ionospheric studies. New meteor radar networks are commencing operation, and this heralds a new area of investigation as the horizontal spatial variation of the upper-atmosphere wind over an extended area is becoming available for the first time. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. The effects of spatial and temporal variations in spawning on offspring survival in Northeast Arctic cod.
- Author
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Endo, C A K, Skogen, M D, Stige, L C, Hjøllo, S S, and Vikebø, F B
- Subjects
- *
SPAWNING , *CODFISH , *SPATIAL variation , *ATLANTIC cod , *CLIMATE change , *TUNDRAS - Abstract
Climate change and harvesting result in temporal and spatial changes and variability in spawning, and thus in offspring ambient drift conditions. As a result, variable survival of offspring and thereby in recruitment are expected. This is especially true for species with long reproduction migration as is the case for some Atlantic cod stocks. We utilize biophysical model simulations to analyze survival from spawning until age 1 resulting from different scenarios of spatial and temporal changes in spawning. We find that survival is 1.5–2 times higher when spawning is shifted southwards as compared to northerly shifts. In general, survival is more sensitive to shifts in spawning location than in spawning time. Early spawning is only favourable if spawning is concurrently shifted farther north. A future spawning scenario with a northward shift in spawning grounds beyond what has been observed historically suggests reduced offspring survival and increased sensitivity to the timing of spawning. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Spatial and temporal variation of seismic b-values across the West Tehran.
- Author
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Azizi, Mehrzad and Saffari, Hamid
- Subjects
- *
SPATIAL variation , *SEISMIC event location , *NATURAL disaster warning systems , *SEISMIC networks , *EARTHQUAKES , *SEISMOGRAMS - Abstract
Until now, numerous efforts have been made to find earthquake precursors. One of the factors that can predict the occurrence of future earthquakes is a decrease in the b-value parameter. In this study, for the metropolis of Tehran, with a population of over 8 million, located on or near many active faults, it is estimated that if the maximum seismic potential of these faults happened again, the greatest disaster in human history would occur. In this case, the analyses indicate a minimum of several hundred thousand casualties and sometimes more than a million. In the current study, various faults around Tehran were investigated, and given that the faults on Tehran have not had serious seismic activity for over a thousand years, this article focused exclusively on adjacent faults, particularly the Eshtehard faults. Therefore, in the current study, the seismicity and tectonics of western Tehran were investigated by analyzing seismic parameters using earthquake data collected from 2003 to 2023. In general, the investigation of the temporal changes in the study area showed that the b-value decreased before the December 20, 2017, earthquake and an increasing trend afterward. Observing anomalies in the b-value before and after the main movement in the area shows that changes in this parameter can be considered a precursor for estimating the time and location of earthquakes. Therefore, a useful step can be taken toward knowing the local seismic hazards by using earthquake data recorded by seismic networks and continuously monitoring the changes in the b-value. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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