Structural Variables Research Articles

Load-Bearing Wing Structures Inspired by Natural Cellular Materials

Abstract This paper presents the optimization frameworks for designing cellular internal structures of an aircraft wing subjected to aerodynamic loads. Inspired by natural cellular materials, this study employs lattice and foam cells as the internal structures of the aircraft wing. The distribution of the cell materials is optimized by minimizing the mass and maximizing the stiffness while avoiding the global buckling of the wing. The optimization variables for the lattice structure are the cell size distribution field and the strut radii (or cell face thicknesses). Various weighting factor combinations are applied to the two competing objectives to obtain the optimal solution, considering different priorities of reducing mass or increasing stiffness. The results demonstrate that the wings with optimized cellular internal structures have higher structural efficiency than the reference wings with uniform cellular internal structures. The optimized wings also achieve higher structural efficiency than conventional wing designs when requiring heavy loading or a balanced trade-off between load-bearing capacity and mass.

Season and Flow Drive Productivity of a Regulated River

Flow regimes of river ecosystems worldwide have undergone substantial changes because of water resource development, altering the way in which organic matter is generated and cycled throughout entire river catchments. Flow–ecology studies have focused on structural variables measured at small spatial scales. This creates a challenging mismatch when applying adaptive flow management for ecosystem functioning at a catchment or regional scale. Here, we sought to inform flow management by evaluating the drivers of ecosystem metabolism in a regulated river and assessing our ability to predict metabolism at unmonitored locations. We estimated rates of ecosystem metabolism from high-frequency monitoring of dissolved oxygen concentration at eight sites on the Lachlan River of Australia’s Murray–Darling Basin. We then applied a spatio-temporal stream network model to predict metabolism at unmonitored locations using only remotely sensed and gauging station predictor variables. Gross primary productivity (GPP) was higher at sites with lower mean annual discharge, and strong seasonal patterns in rates of productivity tended to be disrupted by rising flows. Similarly, ecosystem respiration (ER) was higher at sites with lower mean annual discharge and lower annual flow variation, but increased slightly in response to higher daily flows. Predictions at validation sites were generally accurate, albeit with substantial site-to-site variation. Our results suggest that flow changes may have altered metabolic rates from conditions prior to water abstraction and dam construction. These findings will assist in managing flows for ecosystem function outcomes and support extrapolation from monitored sites to the broad scales required for evaluating catchment-scale outcomes of river management.

Beyond the Toll-Like Receptor 4. Structure-Dependent Lipopolysaccharide Recognition Systems: How far are we?

With an enormous potential in immunology and vaccinology, lipopolysaccharides (LPSs) are among the most extensively studied bacteria-derived molecules. LPS centered studies are countless, and their results reverberate in all areas of the life sciences, including chemistry, biology, genetics, biophysics, and medicine. Most of these research activities are focused on the LPS-induced immune response activation by means of Myeloid Differentiation protein-2/Toll Like Receptor 4 (MD-2/TLR4) complex, which currently is the most largely explored LPS sensing pathway. However, the enormous structural variability of LPS allows interactions with numerous other receptors involved in a wide range of equally important immunological scenarios. In this review, we explore these additional LPS recognition systems, which operate within interconnected signaling cascades, highlighting their role in maintaining physiological homeostasis and their involvement in the development of severe human diseases. Understanding these pathways, their interconnections, and the crosstalk between them and TLR4/MD-2 is essential for guiding the development of pharmacologically active molecules that could specifically modulate the inflammatory response, paving the way to new strategies for combating immune-mediated diseases and resistant infections.

It's all about scale: The landscape effect on avian haemosporidians.

Environmental characteristics drastically shape the host-parasite associations under natural conditions. This is the case of parasites such as avian haemosporidians which naturally infect birds and are transmitted by insect vectors. Landscape characteristics are known to determine the epidemiology of transmission of these parasites in the wild, but the strength of these factors may differ at different spatial scales. We studied the effects of the landscape structure and environmental variables on the prevalence and richness of lineages of avian haemosporidian parasites (genera Plasmodium, Haemoproteus and Leucocytozoon) infecting birds in a highly diverse area of Antioquia, Colombia. We screened blood samples from 678 individuals across 90 bird species for number of infections, prevalence and richness of haemosporidian lineages in sites surrounding three hydroelectric dams. We obtained environmental and landscape structure variables around the bird sampling points at different spatial scales (from 50 to 500m radii, every 50m) and selected the most important ones. We modelled the relationships between parasite infection variables and landscape structural and environmental characteristics. Effects of landscape structure on variables reflecting haemosporidian infections varied according to the selected scale of analyses. The scale of the effect of landscape structure was larger for the number of infections and prevalence (Average=350 and 425m radius) than for lineage richness (Average=Plasmodium 219m, Haemoproteus 244m). Agricultural patch density notably increased number of infection rates (pseudo-R2=0.68). The number of infections and the richness of Haemoproteus lineages correlated with agricultural connectivity at larger scales (500m). Haemosporidian prevalence was primarily linked with proportion forest and agricultural covers. Haemoproteus richness was influenced by connectivity and NDVI - Normalized Difference Vegetation Index (pseudo-R2=0.83), while Plasmodium richness was affected by anthropogenic density, edge density, forest proportion, and temperature (pseudo-R2=0.79). Changes in parasite infection and prevalence remain difficult to predict, as each parasite-host system is susceptible to many unaccounted variables. This study found that transformed landscapes, particularly density of anthropogenic and agricultural patches nearby increases haemosporidian parasites at different scales. These findings underscore the complex interplay between landscape structure and haemosporidian infections in avian hosts in tropical ecosystems.

Exploring the solubility of novel lamotrigine drug–drug salts: the role of pH and structural variability

Strong intermolecular interactions result in decreased pH-dependent solubility of lamotrigine salts.

Avian communities show distinct responses to forest-to-bog restoration.

Since the 1990's, attempted restoration of blanket bogs which have been previously afforested with non-native conifers has taken place in Ireland and Britain, with the aim of reinstating hydrological functioning and hence, peatland biodiversity. Here, we assess the conservation benefit of these restoration measures at sites in the west of Ireland, 16-20 years post works, by comparing avian communities between trios of restored (n=6), near-natural (n=6), and afforested (n=6) lowland blanket bogs. We assessed avian community response in terms of differences in the richness and density of all bird species and of Birds of Conservation Concern in Ireland (BoCCI), as well as community composition. We also investigated which structural habitat variables were responsible for variation in community composition among site types. Restoration resulted in no changes in overall species richness and lower overall bird density but importantly, increased BoCCI richness in comparison to afforested sites. In particular, restoration benefited red-listed species, with richness and density of these species being similar to that of near-natural sites. Avian communities of restored sites were variable but more similar overall to those of near-natural than afforested sites, indicating partial restoration success. Changes in conifer cover, dwarf shrub height, deadwood cover, and broadleaf cover explained the majority of variation occurring across site types. These results indicate that the response of avian communities following forest-to-bog restoration is a prolonged process influenced by the evolving habitat structure, which, in turn, is contingent on the effectiveness of hydrological restoration measures, local conditions and ongoing management.

Estimating the structural and spatial variables of allantoinase enzyme critical for protein adsorption.

Designing enzyme-based sensors necessitates a comprehensive exploration of macromolecular properties. Integrating enzymes with a suitable transducer involves immobilizing them onto a surface, facilitated through adsorption or entrapment techniques. Allantoin, a stable biomarkers metabolite, holds promise for detecting oxidative stress-related complications through its enzyme. In this study, we examined allantoinase from various taxa, with bacterial origin comprising over 70% of the dataset. Crucial residues such as Asp, His, and Gly in the active binding site and associated hydrophobic area play a critical role in maintaining binding specificity and sensitivity. In this work, we utilized bioinformatics tools to analyze properties such as pI, solubility index, amino acid hydropathy, stability, disordered regions, solvent-accessible surface area, and hydrodynamic parameters. The stability of allantoinase is assessed through surface Cys residues, hydrophobicity, and thermostability. Furthermore, the compactness and spherical geometry of the enzyme, which are crucial for protein adsorption are evaluated through parameters like spatial conformation, asphericity, and hydrodynamic radius distribution. Among the dataset, bacterial allantoinase demonstrates significant adaptability to environmental changes, as indicated by solvent-accessible surface area and instability index. This study highlights the importance of macromolecular properties underscoring their significance in optimizing, calibrating, and ensuring the stability of enzyme-based sensor design.

Cryo-EM structure of the human Pannexin-3 channel.

Pannexin-3 (PANX3) is a member of the pannexin family of large-pore, ATP-permeable channels conserved across vertebrates. PANX3 contributes to various developmental and pathophysiological processes by permeating ATP and Ca2+ ions; however, the structural basis of PANX3 channel function remains unclear. Here, we present the cryo-EM structure of human PANX3 at 2.9-3.2Å. The PANX3 channel is heptameric and forms a transmembrane pore along the central symmetric axis. The narrowest constriction of the pore is composed of an isoleucine ring located in the extracellular region, and its size is comparable to that of other pannexins. A structural variability analysis revealed prominent structural dynamics in intracellular regions. Our structural studies provide a foundation for understanding the detailed properties of pannexin channels.

How Does Landscape Structure Affect Dung Beetle Assemblages in Amazon Cities?

The growth of cities is one of the main direct and indirect factors responsible for the loss of native vegetation cover. Urbanization directly affects the biological communities inhabiting forest remnants inserted in cities, compromising the maintenance of urban and natural ecosystems. By understanding the effects of landscape transformation due to urbanization, we can have insights regarding the distribution of land uses that allow a proper maintenance of the urban ecosystems. This work assessed the effects of landscape structure variables (forest cover, agricultural area, edge density, and number of forest patches) on dung beetle assemblages and functional groups (i.e., diet and resource removal strategy) sampled in 38 sites located along an urban-rural gradient of six cities belonging to the metropolitan area of Manaus in Central Amazonia. Losses of forest cover were the most determining factor, negatively affecting species richness, abundance, and body size. The increases in agriculture cover negatively affected dung beetle abundance, while edge density positively affected their abundance. The number of forest patches positively affected dung beetle abundances-except for dweller species-and negatively affected the body size of diet-generalist species. These results demonstrate that changes in ecological diversity caused by urbanization are driven mostly by forest cover loss, although forest configuration is important for dung beetle abundance. This study contributes to the understanding of how changes in the amount and distribution of forest cover in tropical cities affect the taxonomic diversity of dung beetle assemblages.

Decomposition of air pollution in Indonesia

The impact of environmental damage and pollution on health and the economy has become a global concern in recent years, including in Indonesia. In Indonesia, the average number of deaths caused by air pollution is 123,000 yearly, and a decrease in life expectancy by 1.4 - 2.4 years by WHO guidelines. This study investigates the decomposition of air pollution (CO2 emissions) in Indonesia from 1995 to 2022. We imposed structural variables comprising urbanization, liberalization, and fossil-based energy. We also associate renewable energy and environmental policy stringency index to describe the decarbonization skeleton. This study uses a dynamic autoregressive distributed approach to examine the interaction between independent variables and carbon emission levels. The results show a diverse influence of urbanization, liberalization, and fossil fuel when associated with skeleton variables that impact the pattern of pollution shaping. Renewable energy is the most critical factor in promoting inclusive decarbonization, while institutional quality is central to generating robust environmental policies. The implication is that a firm commitment is needed to achieve carbon neutrality through clean technology innovation and renewable energy.

An integrated approach to uncertainty and global sensitivity analysis in penstock structural modeling.

Enhanced penstock structural models significantly advance hydropower engineering, yet their increasing complexity introduces challenges. As model interactions intensify, predictability and comprehensibility decrease, complicating the evaluation of model accuracy and alignment with operational performance metrics and safety standards. This issue is particularly pronounced in dynamic modeling, where knowledge gaps hinder straightforward validation via observational data. Traditional techniques for model calibration and validation are becoming impractical, necessitating a strategic approach to prioritize sources of uncertainty related to critical response variability. This study aims to advance our understanding and management of structural variabilities in penstock models by developing a comprehensive, step-by-step Global Sensitivity Analysis (GSA), designed to meet the specific needs of penstock modeling. Illustrated through a free vibration analysis model of a penstock span, this structured methodology begins with Uncertainty Analysis (UA) to identify variabilities, followed by a screening phase using the Morris method to enhance computational efficiency. Subsequent application of multi-method GSA ranks parameter sensitivities, assesses robustness, and provides a comparative evaluation, providing insights into the effective tools for conducting GSA on penstock models. The process culminates with Regional Sensitivity Analysis (RSA), targeting local sensitivities and enhancing understanding of local parameter influences, thereby supporting model adjustments and design optimization. Results from this application characterize model sensitivities for the most prominent mode shapes to specific structural parameters and indicate that these sensitivity outcomes are influenced by variability in parameter spaces and output sub-range definitions. This study provides a practical framework for addressing uncertainties in penstock design, enhancing model accuracy, prioritizing parameters, managing risks, and improving the reliability and efficiency of hydropower infrastructure.

Landscape Effects on Local Species Richness of Woody Specialists in Subtropical Montane Cloud Forest of Taiwan

ABSTRACTAimHow is the local species richness of woody specialists in vegetation plots located within subtropical montane cloud forests (SMCFs) affected by the landscape structure of the surrounding SMCF habitat patch?LocationSubtropical montane cloud forests in Taiwan.TaxonWoody species specialised in growing in foggy conditions.MethodsWe used plant occurrence data from major herbaria together with fog frequency data to identify fog specialists of SMCFs in Taiwan. Subsequently, we extracted 20 × 20 m forest vegetation plots from the National Vegetation Database of Taiwan and calculated the richness of woody specialists in each of them. Using a published predicted SMCFs distribution map, we estimated the landscape context of SMCFs around each vegetation plot within circular buffer zones of increasing radius. The variables of landscape structure include those related to the area of SMCFs habitat (area and connectivity), surrounding heterogeneity (topographical heterogeneity and vegetation diversity) and edge effect (the nearest distance from the plot to the edge and the edge length). The multiple linear regression model was used to investigate which of the three mechanisms of landscape context has the strongest effect on the local richness of fog specialists.ResultsOnly the area of SMCFs habitat patch shows a significant positive effect on the local species richness of woody specialists in the plot when considering all the landscape variables. Area per se might be a possible mechanism that supports this positive species‐area relationship. Additionally, the area of SMCFs patch is highly correlated with connectivity, indicating that larger SMCF patches enhance connectivity beyond buffer zones, sustaining species through the rescue effect from the regional species pool.Main ConclusionsPatch size and connectivity are crucial for the species richness of woody specialists in SMCFs in Taiwan. For conservation, we recommend protecting larger, less fragmented SMCF patches to maintain biodiversity.

Optimizing Dynamic Properties of Dissimilar Plate Structures: A Model Updating and Response Surface Methodology Approach

This paper presents a comprehensive exploration of a multi-objective optimization methodology targeting structural parameters to enhance the dynamic properties of dissimilar structures, emphasizing the integration of experimental and numerical modal analysis techniques. In this study, the correlation technique was employed to compare the modal data obtained from FEA with experimental modal analysis, revealing that the CBAR element exhibited the least error rate of 0.86% among the modes, indicating its superior accuracy in simulating bolted structures. Subsequent model updating processes effectively improved the natural frequency predictions, particularly for NF2, leading to an overall reduction in error from 4.65% to 3.08%. Additionally, the RSM approach successfully optimized the structural design variables, achieving a desirability rate of 0.937 and indicating a significant reduction in percentage error. The comparison between the two optimization methods demonstrated their respective strengths, with model updating offering greater precision in setting boundaries, and RSM providing efficient mathematical models for optimization. This study provides valuable insights into the effective enhancement of dynamic properties for dissimilar plate structures, underscoring the significance of both optimization techniques for achieving superior accuracy in structural analysis and design.

Analysis of complete genomes of Mycobacterium tuberculosis sublineage 2.1 (Proto-Beijing) revealed the presence of three pe_pgrs3-pe_pgrs4-like genes

Mycobacterium tuberculosis Complex (MTBC), the etiological agent of tuberculosis (TB), demonstrates considerable genotypic diversity with distinct geographic distributions and variable virulence profiles. The pe-ppe gene family is especially noteworthy for its extensive variability and roles in host immune response modulation and virulence enhancement. We sequenced an Mtb genotype L2.1 isolate from Chiangrai, Northern Thailand, using second and third-generation sequencing technologies. Comparative genomic analysis with two additional L2.1 isolates and two L2.2.AA3 (Asia Ancestral 3 Beijing) isolates revealed significant pe-ppe gene variations. Notably, all L2.1 isolates harbored three copies of pe_pgrs3-pe_pgrs4-like genes (pe_pgrs3*, pe_pgrs4*, and pe_pgrs4), different from L2.2.AA3 and H37Rv strains. Additionally, ppe53 was duplicated in all but H37Rv, and ppe50 was deleted in L2.1 isolates, contrasting with an extended ppe50 in an L2.2 isolate (Mtb 18b), which contains an additional SVP motif. Complete deletion of ppe66 and loss of wag22 were observed in L2.1 isolates. These findings highlight the high structural variability of the pe-ppe gene family, emphasizing its complex roles in Mtb-host immune interactions. This genetic complexity offers potentially critical insights into mycobacterial pathogenesis, with significant implications for vaccine development and diagnostics.

Landscape influences bat suppression of pine processionary moth: Implications for pest management.

Bats provide important ecosystem services, particularly in agriculture, yet integrating bat management into conservation plans remains challenging. Some landscape features considerably influence bat presence, diversity, and ecosystem service provision. Understanding the relationship between landscape structure, composition, pest suppression, and ecosystem services is crucial. We modelled areas where bats most effectively suppress pine processionary moths (Thaumetopoea pityocampa), considering landscape characteristics to predict ecosystem services and optimise pest suppression in Serra da Estrela, Portugal. Faecal samples collected during fieldwork were analysed for pine processionary moth presence in bat diets. Lasso regression assessed spatial landscape variables to create an "optimal landscape" for predation. Landscape structure and composition influenced pest suppression differently, with the greatest impact within a 5000-m buffer. "Riparian edge" and "tree cover density" were key habitat structure variables supporting bat navigation and access to hunting areas, while "other forest" and "vineyard/orchard" areas were important composition variables. Optimising landscape composition involves incorporating diverse forest within agroforestry systems to enhance pest suppression by creating habitats reflecting bats' foraging preferences. We recommend strategies focusing on riparian edge conservation, selective canopy reduction, and promoting diverse forest compositions. These strategies aim to create mosaic landscapes balancing land uses, fostering optimal conditions for bat foraging. Our study shows edges provide the highest rates of bats-pine processionary moth interactions. However, caution is needed to avoid excessive fragmentation, which may reduce habitat suitability and increase pest presence before effective bat predation. A balanced approach, focusing on edge creation without over-fragmenting the landscape, is key to promoting sustainable pest management.

Managing south-east Asia’s savannas: challenges and holistic approaches through community-based fire management

Savannas, characterised by a continuous grass layer and discontinuous tree layer, are widespread globally and highly flammable during dry seasons, contributing to 90% of annual global burned areas and significant emissions. Asian savannas, often mismanaged owing to structural variability and misclassification as ‘poor forests’, face excessive or insufficient fire regimes. Addressing trans-boundary haze and climate mitigation requires improved understanding and sustainable management. This paper addresses savanna management challenges, particularly misclassified dry dipterocarp forests in the Lower Mekong, by synthesising knowledge on their distribution and the role of fire use by local communities, and recommends holistic, community-based fire management, integrated planning and incentives.

Structure Design and Optimization of MRE Vibration Isolator

As an intelligent component, the high-performance MRE vibration isolator has great advantages, such as a wide vibration isolation frequency range and good performance in semi-active vibration reduction applications. In order to develop high-performance MRE devices, Firstly, this paper makes use of the advantages of real-time tracking/away from external excitation frequency of MRE devices, analyzes the working mode of MRE, and designs a shear MRE vibration isolator based on airborne equipment. Secondly, the material selection and magnetic circuit analysis of the MRE are also completed, and the magnetic field in the MRE region is maximized under the same input energy, thus improving the working efficiency of the MRE isolator. Finally, the relationship between magnetic induction intensity and structural size variables is established by the finite element method and the structural dimensionless method. Based on COMSOL multi-physics simulation software (version 6.0), the global optimization is carried out, the results show that the optimal solution satisfying the comprehensive index of optimal vibration isolation performance of the MRE isolator is obtained, then the structural parameters of the isolator are optimized, and its magnetic control performance is improved. The MRE vibration isolator designed in this paper meets the vibration isolation requirements of airborne optical equipment and has certain engineering application value.

A Predictive Analysis of Beach Susceptibility to Jellyfish Arrivals in Costa del Sol

This study investigates the susceptibility of beaches to jellyfish arrivals, focusing on the summer seasons from 2015 to 2020. The objective was to develop a predictive model that identifies the characteristics of beaches prone to higher jellyfish presence. This research utilized data from the Infomedusa application, with a focus on key structural and circumstantial variables, such as beach orientation, coastal currents, and morphology. Binomial logistic regression was applied to two models to assess the influence of these variables on jellyfish occurrence. The results showed that beaches oriented toward the east and south, with protection from natural or artificial barriers, and those with limited open sea exposure are more likely to experience jellyfish arrivals. Conversely, beaches facing southwest, with opposing currents and freshwater inflows, tend to have lower risks. Although the models’ predictive capacity was moderate, with a 76% validation rate against empirical data, they provided valuable insights for coastal management and risk prevention. The findings highlight the importance of beach-specific characteristics in forecasting jellyfish presence, contributing to more effective coastal protection strategies.

The Effect of Capital Structure, Profitability, Liquidity, and Solvency on Firm Value with Managerial Ownership as a Moderating Variable in Food and Beverage Sub-Sector Companies Listed on the Indonesia Stock Exchange 2020-2023

The purpose of this study was to analyze how the influence of capital structure, profitability, liquidity, and solvency, can affect firm value moderated by managerial ownership in food and beverage sub-sector companies listed on the Indonesia Stock Exchange (IDX) for the period 2020-2023. This research was conducted on food and beverage sub-sector companies listed on the IDX, data information was obtained through the official website of the Indonesia Stock Exchange www.idx.com, the sampling technique used purposive sampling with a population of 94 food and beverage companies listed on the Indonesia Stock Exchange for the period 2020-2023 and a sample of 16 companies. Tests were carried out with regression panel data analysis and Moderated Regression Analysis (MRA) using E-views statistical data processing software. The results of this study indicate that liquidity and solvency variables have no significant effect on firm value, capital structure variables and profitability have a significant effect on firm value. Managerial ownership is also unable to moderate the relationship between capital structure, profitability, liquidity, and solvency on firm value.

Interactions Determining Stereoselectivity in Two-Dimensional Systems─The Case of 22-Hydroxycholesterol Epimers.

Oxidized derivatives of cholesterol play an important role in the functioning of biomembranes. Unlike other biomolecules, which are physiologically active in only one enantiomeric form, some oxysterols exist endogenously as two stereoisomers that exhibit strictly different biological effects. In this paper, we focused our attention on 22-hydroxycholesterol (22-OH) epimers, 22(R)-OH and 22(S)-OH, and examined their properties in Langmuir monolayers spread at the air/water interface, using classical surface manometry complemented with Brewster angle microscopy (BAM) images of the film texture. The studied epimers showed quite different monolayer characteristics. Namely, 22(S)-OH formed homogeneous, condensed monolayers of high collapse pressure, while 22(R)-OH films were more disordered and expanded with quite low collapse pressure. Interestingly, the latter compound showed in the course of the surface pressure-molecular area isotherm a temperature-dependent plateau transition, characterized by the coexistence of domains of molecules with different inclinations, visible in BAM images as patches of varying brightness. Molecular dynamics (MD) simulations confirmed this and revealed that the greater structural variability of 22(R)-OH is due to the greater hydration of the oxygen atom at C(22) compared to the other epimer. Next, we tested whether 22-OH epimers could differentiate interactions with sphingomyelin (SM). Although the strength of interaction with SM was similar for both epimers, the composition of the films corresponding to this minimum was different. With the aid of MD, it was found that these differences result directly from the interplay between 22-OH molecules and their ability for hydrogen bond formation. Therefore, the stereochemistry of oxysterols seems to play a crucial role in the overall structural organization of the membrane.