High Density Research Articles

Spatially Localized Visual Perception Estimation by Means of Prosthetic Vision Simulation

Retinal prosthetic devices aim to repair some vision in visually impaired patients by electrically stimulating neural cells in the visual system. Although there have been several notable advancements in the creation of electrically stimulated small dot-like perceptions, a deeper comprehension of the physical properties of phosphenes is still necessary. This study analyzes the influence of two independent electrode array topologies to achieve single-localized stimulation while the retina is electrically stimulated: a two-dimensional (2D) hexagon-shaped array reported in clinical studies and a patented three-dimensional (3D) linear electrode carrier. For both, cell stimulation is verified in COMSOL Multiphysics by developing a lifelike 3D computational model that includes the relevant retinal interface elements and dynamics of the voltage-gated ionic channels. The evoked percepts previously described in clinical studies using the 2D array are strongly associated with our simulation-based findings, allowing for the development of analytical models of the evoked percepts. Moreover, our findings identify differences between visual sensations induced by the arrays. The 2D array showed drawbacks during stimulation; similarly, the state-of-the-art 2D visual prostheses provide only dot-like visual sensations in close proximity to the electrode. The 3D design could offer a technique for improving cell selectivity because it requires low-intensity threshold activation which results in volumes of stimulation similar to the volume surrounded by a solitary RGC. Our research establishes a proof-of-concept technique for determining the utility of the 3D electrode array for selectively activating individual RGCs at the highest density via small-sized electrodes while maintaining electrochemical safety.

Characterizing juvenile blacktip shark (Carcharhinus limbatus) nursery areas in the Galapagos: new methods and understandings.

New approaches to abundance surveying utilizing unoccupied aerial vehicles (UAVs) are proving to be effective tools in marine and terrestrial environments. We explored UAV efficacy for surveys in the Galapagos Marine Reserve (GMR), where relative abundance patterns of juvenile sharks and subsequent classifications of putative nursery areas based on environmental drivers are lacking. The UAV method allowed greater temporal and spatial coverage. We expanded classification of shark nursery habitat through monthly drone surveys and environmental data collection at 14 sites around San Cristobal Island (GMR) from November 2018 to July 2019. In the period of surveying, 56 flights identified 453 juvenile Carcharhinus limbatus (blacktip shark). Classification of nurseries followed three criteria, necessitating higher density, short-term residency, and annual site fidelity in target locations. We developed preliminary generalized linear models to elucidate potential environmental parameters influencing the perceived abundance and habitat preference of juveniles. Four sites were identified as either potential nurseries or nursery areas for the target species based on previous excursions. An averaged model was subsequently created from the models found to best explain deviance patterns (R2 = 0.10-0.44) in perceived shark abundance and habitat preference. Relative variable importance (RVI) values further clarified the parameters most associated with higher juvenile presence. This approach provides a systematic method of abundance surveying while simultaneously beginning the process of defining when and where we expect to find higher abundance through environmental modelling of most influential parameters to perceived abundance in this environment.

Factors Influencing Corneal Endothelial Cell Density after Descemet Stripping Automated Endothelial Keratoplasty

Purpose: To identify determinants of corneal endothelial cell density at 12 months after Descemet stripping automated endothelial keratoplasty (DSAEK).Methods: This study included patients with bullous keratopathy who underwent DSAEK with internationally sourced donor corneas from March 2021 to March 2022. We assessed various preoperative factors in recipients (age, cause of bullous keratopathy, intraocular pressure, visual acuity, anterior chamber volume, depth and angle, pupil size, white-to-white corneal diameter, and preoperative corneal endothelial cell density) and donors (age, death to preservation time, preservation to transplantation time, death to transplantation time, corneal endothelial cell density, trephine size, and precut tissue thickness). We analyzed factors influencing corneal endothelial cell density up to 12 months after keratoplasty.Results: This study involved 53 patients, with an average recipient age of 65.9 ± 14.6 years prior to surgery. Donor corneas had an average endothelial cell density of 2,871.6 ± 271.6 cells/mm<sup>2</sup>. At 6 and 12 months postoperatively, endothelial cell densities had decreased by 36.9% and 47.2%, respectively, compared with preoperative levels. Multivariate linear regression analysis indicated that endothelial cell densities at 3 and 12 months postoperatively were linked to recipient age and anterior chamber depth.Conclusions: Corneal endothelial cell density after DSAEK typically stabilized after initial decline; higher densities were found in older recipients and individuals with shallower anterior chambers.

Impact of Cassava Cultivars on Stylet Penetration Behavior and Settling of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)

This study investigates the settling preferences and feeding behavior of the Bemisia tabaci whitefly on six cassava cultivars using electrical penetration graph techniques. Six distinct electrical penetration graph waveforms—non-probing, stylet pathway, phloem salivation, phloem ingestion, intracellular puncture, and xylem feeding—were identified and analyzed. Significant differences in the frequency and duration of these waveforms were observed among the cassava cultivars. The whiteflies spent the majority of their time in the non-probing phase, particularly on the Huaybong 80, Kasetsart 50, Rayong 9, and Rayong 72 cultivars. CMR-89 cultivar exhibited higher total probe durations in the phloem salivation and ingestion waveforms, suggesting a greater potential for transmission of the Sri Lankan cassava mosaic virus. The study also examined trichome density and size across the cassava cultivars, revealing that CMR-89 had the highest density and small trichomes, while Huaybong 80 had the lowest density. Trichome characteristics significantly impacted whitefly behavior: larger trichomes were negatively correlated with whitefly settling, whereas higher trichome density was positively correlated with longer settling durations. These findings indicate that trichome-based resistance mechanisms are crucial in whitefly deterrence. Overall, the results suggest that cultivars with lower trichome density and larger trichomes are more resistant to whitefly infestation and subsequent Sri Lankan cassava mosaic virus transmission. These insights are valuable for cassava breeding programs focused on enhancing pest resistance, highlighting the importance of trichome characteristics in developing more resilient cassava varieties.

Genomic Prediction Using Imputed Whole-Genome Sequence Data in Australian Angus Cattle.

Whole-genome sequence (WGS) data was used to estimate genomic breeding values for growth and carcass traits in Australian Angus cattle. The study aimed to compare the accuracy and bias of genomic predictions with three marker densities, including 50K, high-density (HD) and WGS. The dataset used in this study consisted of animals born between 2013 and 2022. Body weight traits included birthweight, weight at 400 days and weight at 600 days of age. The carcass traits were carcass weight, carcass intramuscular fat and carcass marbling score. The accuracy and bias of prediction were assessed using the cross-validation. Further, for the growth traits, animals in the validation group were subdivided into two subgroups, which were moderately or highly related to the reference. Genomic best linear unbiased prediction (GBLUP) was used to compare genomic predictions with the three marker densities. The prediction accuracies were generally similar across the marker densities, ranging between 0.61 and 0.68 for the body weight traits and between 0.40 and 0.52 for the carcass traits. However, the accuracies marginally decreased as the marker density increased for all the traits studied. A similar lack of difference was found when considering the accuracy by the relatedness subgroups. The results indicated that no meaningful difference in prediction accuracy was estimated when comparing the three marker densities due to the population structure. In conclusion, there was no substantial improvement in genomic prediction when using the WGS in this study.

Empirical versus estimated accuracy of imputation: optimising filtering thresholds for sequence imputation.

Genotype imputation is a cost-effective method for obtaining sequence genotypes for downstream analyses such as genome-wide association studies (GWAS). However, low imputation accuracy can increase the risk of false positives, so it is important to pre-filter data or at least assess the potential limitations due to imputation accuracy. In this study, we benchmarked three different imputation programs (Beagle 5.2, Minimac4 and IMPUTE5) and compared the empirical accuracy of imputation with the software estimated accuracy of imputation (Rsqsoft). We also tested the accuracy of imputation in cattle for autosomal and X chromosomes, SNP and INDEL, when imputing from either low-density or high-density genotypes. The accuracy of imputing sequence variants from real high-density genotypes was higher than from low-density genotypes. In our software benchmark, all programs performed well with only minor differences in accuracy. While there was a close relationship between empirical imputation accuracy and the imputation Rsqsoft, this differed considerably for Minimac4 compared to Beagle 5.2 and IMPUTE5. We found that the Rsqsoft threshold for removing poorly imputed variants must be customised according to the software and this should be accounted for when merging data from multiple studies, such as in meta-GWAS studies. We also found that imposing an Rsqsoft filter has a positive impact on genomic regions with poor imputation accuracy due to large segmental duplications that are susceptible to error-prone alignment. Overall, our results showed that on average the imputation accuracy for INDEL was approximately 6% lower than SNP for all software programs. Importantly, the imputation accuracy for the non-PAR (non-Pseudo-Autosomal Region) of the X chromosome was comparable to autosomal imputation accuracy, while for the PAR it was substantially lower, particularly when starting from low-density genotypes. This study provides an empirically derived approach to apply customised software-specific Rsqsoft thresholds for downstream analyses of imputed variants, such as needed for a meta-GWAS. The very poor empirical imputation accuracy for variants on the PAR when starting from low density genotypes demonstrates that this region should be imputed starting from a higher density of real genotypes.

Drug release kinetics from in-situ modulated agar/chitosan-bacterial cellulose patches for differently soluble drugs.

Bacterial cellulose (BC) stands out as a promising candidate for novel drug delivery systems due to its micro-mesoporous nanofibrous interconnected structure. However, its performance is limited by the burst release of hydrophilic drugs and lower incorporation of the less water-soluble or insoluble drugs. In this study, we explored its potential as a drug carrier for two distinct types of drugs: Diclofenac sodium and Simvastatin, representing water-soluble and water insoluble compounds, respectively. To tune the morphology and drug-BC interaction, agar and chitosan were introduced into the culture medium during BC synthesis for in-situ modification. These modulated BCs are characterized and further analyzed through drug release studies and mathematical modeling to understand the mechanisms and key factors controlling the drug release behavior. Incorporating agar and chitosan into the BC network results in changes to its microstructure and crystallinity, which in turn affects the overall swelling, drug loading and release properties. Our results revealed that the BC followed a first-order quasi-Fickian kinetics for water-soluble drug and non-Fickian release mechanism for water-insoluble drug. In contrast, agar-modulated BC (A-MBC) demonstrated a non-Fickian first-order diffusion kinetics, with slow release for water-soluble drug and sustained release for the water-insoluble drug due to the higher density which impedes drug release. Chitosan-modulated BC (C-MBC) exhibited non-Fickian first-order kinetics, with slower release for water soluble drug. Further, C-MBC exhibited extended release for water insoluble drug to over 14 days, following first-order kinetics for the first 12 h, then transitioning to zero-order kinetics with a Case II release mechanism, attributed to drug-matrix interactions. These findings successfully demonstrate the possibility to tailor BC thus the release kinetics for both water-soluble and less soluble or insoluble drugs.

Hydraulic and structural traits of trees across light gradients in the Amazon secondary forest.

Amazonian species are generally unable to adapt to long drought periods, indicating a low capacity to adjust their hydraulic traits. Secondary forests account for 20% of forest cover in the Amazon, making natural regeneration species crucial under climate change scenarios. In this study, we compared the hydraulic traits of five species, including non-pioneers (Bertholletia excelsa Bonpl., Carapa guianensis Aubl., Hymenaea courbaril L.) and pioneers (Cedrela fissilis Vell., Tabebuia rosea (Bertol.) Bertero ex A.DC.), across light conditions (understory, intermediate, gap) in a 22-year-old secondary forest in Central Amazon, Brazil. Twenty-five saplings were planted and monitored in 3 plots × 5 blocks. Five years after the plantation, we assessed growth, wood density, leaf water potential at predawn and midday, xylem embolism resistance (P50), and hydraulic safety margins (HSM). Leaf water potential ranged from -2.9 to 0MPa. The non-pioneer species C. guianensis and H. courbaril exhibited the lowest P50 (-4.06MPa), indicating higher embolism resistance, whereas the pioneer T. rosea had the highest P50 (-1.25MPa), indicating lower resistance. HSM varied from -1.60 to 3.26MPa, with lower values in gap conditions during the dry period (-1.60MPa), especially affecting pioneer species. Wood density was influenced by both light and species type, with non-pioneers showing generally higher density, with H. courbaril reached 0.75gcm-3 in the understory while the pioneer T. rosea showed the lowest density (0.27gcm-3). These results highlight that light conditions affect hydraulic traits differently across species strategies, especially during early growth. Non-pioneer, slow-growing native species appear more resilient to light variation, making them suitable for future plantations aimed at climate adaptation in secondary forests.

Self-assembly and phase behavior of Janus rods: Competition between shape and potential anisotropy.

We characterize the self-assembly and phase behavior of Janus rods over a broad range of temperatures and volume fractions, using Langevin dynamics simulations and free energy calculations. The Janus rods consist of a line of fused overlapping spheres that interact via a soft-core repulsive potential, with the addition of an attractive pseudo-square-well tail to a fraction of the spheres (the coverage) ranging from 5% to 100% of sites. Competition between the stability of liquid crystal phases originating from shape anisotropy and assembly driven by directional interactions gives rise to a rich polymorphism that depends on the coverage. At low densities near the Boyle temperature, we observe the formation of spherical and tubular micelles at low coverages, while at higher coverages, randomly oriented monolayers form as the attractive parts of the rods overlap. At higher densities, bilayer structures appear and merge to form smectic and crystalline lamellar phases. All these structures gradually become unstable as the temperature is increased until eventually regular nematic and smectic phases appear, consistent with the hard rod limit. Our results indicate that the intermediate regime where shape-entropic effects compete with anisotropic attractions provided by site specificity is rich in structural possibilities and should help guide the design of rod-like colloids for specific applications.

Mechanical properties of beech wood treated with malic acid-based polyester

Abstract While chemical modification enhances wood’s resistance to deterioration and dimensional stability, it often results in alterations to the mechanical properties, limiting its engineering applications. This study focuses on the in situ esterification of beech wood using malic acid/polyol mixtures and evaluates its impact on mechanical properties. The results of the compression tests yielded limited information, characterized by a notable degree of variability as indicated by the high standard deviation. The four-point bending tests conducted here revealed an increase in the modulus of elasticity (MOE). However, this improvement in MOE was accompanied by a decrease in the modulus of rupture (MOR), indicating a trade-off between stiffness and strength. To better understand the mechanisms affecting the treated wood’s mechanical properties, we compared the experimental and theoretical glass transition (Tg) of the polymers with material stiffness. X-ray computed tomography revealed that treatment increases specimen density and creates a gradient, with higher density near the surface, potentially contributing to increased stiffness. These findings suggest a nuanced impact of the in situ esterification process using malic acid/polyol mixtures on the mechanical properties of beech wood.

Rosettes in a matrix: Predicting spatial variation in density of a large felid in a forest‐production mosaic

AbstractLarge carnivores are keystone for ecosystems and flagships for conservation efforts but face severe threats globally. Protected areas are vital for the conservation of these charismatic species along with a host of ecological processes. However, the extent and scope of protected areas for conservation of all threatened species is limited, especially in the global south. Considering larger landscapes that can be compatible with large carnivore conservation goals is an alternative approach to ensure their persistence. This study explores the potential of multi‐use landscapes for the persistence of a globally threatened large felid, the Indian leopard (Panthera pardus fusca). This study investigated the spatial variability of leopard densities across a land‐use gradient using spatially explicit capture‐recapture framework in a tea‐plantation‐dominated forest‐production landscape mosaic in the Duars region of northeastern India. While the density of leopards in this landscape was estimated to be 7.96 ± 1.56 (SE) per 100 km2, significant (p = .048, t = 2.02, df=61) differences in estimates were observed between tea‐plantations (11.53 ± 2.72 (SE) leopards per 100 km2) and the forested habitats (4.67 ± 2.07 (SE) per 100 km2). Densities between tea plantations and protected areas (a subset of the forested habitat) were found to be comparable (9.19 ± 4.55 (SE) per 100 km2). The study posits that conservation‐compatible land use in landscapes shared with people can host a higher density of adaptable large felids like leopard than forested areas and that conservation planning needs to move beyond the dominant PA‐centric paradigm. The study also reinforces the importance of multi‐use landscapes for wildlife conservation, especially for an adaptable large felid.

Non‐breeding home range and habitat use by European Pied Flycatcher (Ficedula hypoleuca) in northwest Liberia: apparent resilience to forest degradation?

Identifying population drivers of migratory birds requires knowledge of species' ecology throughout their annual cycle. For most Afro‐Palaearctic migratory species, little is known about non‐breeding habitat use, despite extensive land use change in non‐breeding areas of sub‐Saharan Africa being a key factor implicated in population decline. We radio‐tracked 54 Pied Flycatchers Ficedula hypoleuca at two sites of differing levels of forest disturbance, in Liberia, western Africa, over three non‐breeding seasons to determine home range size and site fidelity, and describe habitat and tree species preference within home ranges. We found high territory fidelity both within and between years, and a preference for well‐wooded landscapes. We found that Pied Flycatcher presence was positively associated with large and mature trees, and areas with a higher density of trees. Pied Flycatchers preferred several tree species that were uncommon within home ranges, and several non‐native tree species likely to support a high invertebrate abundance. Pied Flycatchers preferentially selected areas burnt in the same or previous winter, possibly related to enhanced food resources associated with vegetation regrowth following burning. We also found no significant difference in home range size between sites and similar habitat associations despite differences in habitat disturbance. This suggests that human‐modified habitats may remain suitable for Pied Flycatchers, as long as they retain moderate tree cover, especially larger, taller and more mature trees, whether native or non‐native.

Overview of plant species translocations in Luxembourg

In Luxembourg, 34 % of native plants and archaeophytes are considered threatened or regionally extinct. Species translocations have been implemented in Luxembourg for more than 25 years as a conservation strategy to counteract biodiversity loss. In this overview, we have compiled data on conservation actions implemented between 1997 and 2023. The information collected includes the translocation locations, the plant taxa targeted, the methods used, and the monitoring conducted. For a subset of translocations, we have also included data on the survival of planted juveniles. Examples of translocations from various habitat types were also presented to illustrate different approaches. We found that 585 translocations involving 99 taxa from 26 families were initiated by four main institutions in Luxembourg. The conservation actions mainly targeted Endangered and Critically Endangered, but also Least Concern species. Translocations mainly took place in open land habitats, particularly in grasslands and arable land, with a higher density in the southwestern part of the country. 39 % of the translocations took place in national nature reserves whereas 21 % were in areas without any legal protection status. Planting young plants was the preferred method rather than sowing seeds. In 89 % of the translocations, monitoring was conducted by recording survival of the plants, while natural recruitment of new individuals was rarely recorded. 68 % of the translocations were judged successful by the practitioners, mostly based on transplant survival. Detailed data for the subset of 31 grassland species showed that the survival rate of about half of the species considered successful varied between 25 and 71 %. Translocations are essential for the long-term conservation of plant species, but protection and adaptive management of translocation sites are also essential. Translocations conform to national and European priorities for increasing habitat restorations to counteract species decline. To improve conservation outcomes, actions such as translocations need to be consistently documented, monitoring standardized, and experience needs to be shared among stakeholders.

IMMU-23. NEOADJUVANT ANTI-PD-1 AND ANTI-CTLA-4 COMBINATION THERAPY INDUCED INTRATUMORAL IMMUNOLOGIC ALTERATIONS IN RECURRENT GBM PATIENTS

Abstract Glioblastoma (GBM) is a highly aggressive brain tumor that responds poorly to checkpoint blockade inhibitors (ICIs), such as anti-PD-1. We previously reported that neoadjuvant anti-PD-1 therapy activated and recruited T cells into recurrent GBM (rGBM) tumors, but also increased immune checkpoint interactions between T cells and myeloid cells. To overcome this resistance mechanism, we are currently conducting a phase 1B clinical trial of neoadjuvant anti-PD-1 (Nivolumab, BMS) +/- anti-CTLA-4 (Ipilimumab, BMS) combination therapy for rGBM patients (NCT04606316). To evaluate the local tumor microenvironment effects of these checkpoint inhibitors, we used multiplex immunofluorescence (mIF), bulk RNA sequencing, and T cell receptor sequencing to analyze the intratumoral immune profile of tumors. Using mIF, we are able to determine the density of key immune cell phenotypes within the section of tumor sample as well as the proximity between phenotypes to better understand their interactions. Patients who received the combination therapy (n=15) trended to have a higher median density of cytotoxic T cells (CD45+CD8+; median density of 27.13 cells/mm2 for combination therapy and 13.78 cells/mm2 for anti-PD-1), helper T cells (CD45+CD4+; median density of 33.73 cells/mm2 for combination therapy and 9.82 cells/mm2 for anti-PD-1), monocytes (CD14+), and HLA-DR+ macrophages (CD45+CD14+HLA-DR+) while patients treated with anti-PD-1 alone (n=16) trended to have densities similar to placebo treated patients (n=6). Patients treated with combination therapy are also trending to have a higher density of macrophages in close proximity (≤20μm) to T cells, particularly HLA-DR+ macrophages, suggesting a higher frequency of interactions within their tumor microenvironments. This data set is currently incomplete, but the final data set will be completed by the meeting. Nonetheless, these preliminary results, as well as the bulk RNA sequencing and T cell receptor sequencing, suggest distinct immunologic effects of monotherapy vs. combination neoadjuvant anti-PD-1 and anti-CTLA-4 therapy in the tumor microenvironment of rGBM patients.

Energy relaxation of N2O in gaseous, supercritical, and liquid xenon and SF6.

Rotational and vibrational energy relaxation (RER and VER) of N2O embedded in xenon and SF6 environments ranging from the gas phase to the liquid, including the supercritical regime, is studied at a molecular level. Calibrated intermolecular interactions from high-level electronic structure calculations, validated against experiments for the pure solvents, were used to carry out classical molecular dynamics simulations corresponding to experimental state points for near-critical isotherms. The computed RER rates in low-density solvents of krotXe=(3.67±0.25)×1010 s-1 M-1 and krotSF6=(1.25±0.12)×1011 s-1 M-1 compare well with the rates determined by the analysis of two-dimensional infrared experiments. Simulations find that an isolated binary collision description is successful up to solvent concentrations of ∼4 M. For higher densities, including the supercritical regime, the simulations do not correctly describe RER, probably due to the neglect of solvent-solute coupling in the analysis of the rotational motion. For VER, the near-quantitative agreement between simulations and pump-probe experiments captures the solvent density-dependent trends.

Life Cycle Assessment and Experimental Mechanical Investigation of Test Samples for High-Performance Racing Boats

This paper investigates the environmental impact and mechanical performance of two composite sandwich structures, named Series 1 and Series 2, used in high-performance racing boats. Mechanical tests, including four-point bending and drop impact tests, were performed. It was found on a general basis that Series 2 has higher load-bearing capacity and limited deflection. Series 1, which has a higher density, was able to absorb more impact energy but was more susceptible to damage. A Life Cycle Assessment (LCA) was conducted to evaluate the environmental impact associated with the materials, considering also the testing phase, which plays an important role in the life cycle of materials and structures for advanced marine applications. In addition, two performance indexes were introduced to correlate the mechanical and environmental properties of the analyzed materials. This study emphasizes the importance of considering the testing phase in LCA, as the energy-intensive nature of mechanical testing contributes significantly to the overall environmental impact. The introduced indexes allow for a more comprehensive understanding of the balance between mechanical performance and environmental sustainability. The findings suggest a trade-off between mechanical performance and sustainability, calling for further research into recyclable composites and greener manufacturing processes to balance these competing priorities.

Warming promotes expansion of a key demersal fishing resource of the western Mediterranean

Climate change is affecting marine ecosystems altering the distribution and abundance of organisms, with implications for fisheries and food security. This warming-induced reshuffle in species abundance could bring threats and opportunities to the fisheries, but needs to be assessed to promote effective actions and to foster resilience. We analyzed the density and distribution patterns of deep-sea rose shrimp (Parapenaeus longirostris), as well as identified the main environmental have identified the environmental drivers shaping its habitat along the western Mediterranean (Iberian Peninsula) during the period 2001–2020. Using spatial distribution models developed concurrently with an ensemble of four Regional Climate Models (RCMs), we have projected the density of this species during the next century under two climate scenarios (RCP4.5 and RCP8.5). Bathymetry and sea bottom temperature drove the density of the species, leading to a marked northward expansion during the last two decades. Our results projected an increase in its distribution and especially in density throughout the area along the 21st century, mirroring the effect of global warming. Consequently, the most distant period (i.e. 2100s) and the warmest scenario (RCP8.5) presented also the highest densities and low internal variability of the ensemble. We discussed the power of assessing uncertainties using a RCM ensemble, particularly under complex oceanographic features, to bring robust information for an effective scientific advice to fisheries management.

Executive Compensation: The Role of Human Capital and Geographic Preferences

Human capital is crucial for sustainable competitive advantage, and certain workforce groups have a greater impact than others. The top management team, responsible for directing firm strategy and structure, is one such group, and executive turnover can be detrimental for a firm. While existing literature often suggests that executives change jobs primarily for higher pay, this is not always true. Drawing on human capital research and the geographic preference theory, we examine how an executive’s human capital and geographic preferences affect changes in compensation during job transitions. Using a sample of 351 executives who moved among S&P 500 companies from 2000 to 2015 (378 inter-organizational moves), we find that education (a proxy for human capital) and area desirability (a proxy for geographic desirability) correlate with changes in executive compensation. Additionally, a higher density of geographically proximal executive pay packages increases an executive’s compensation premium when changing jobs.

Multi‐aspect assessment and multi‐objective optimization of preheated tallow biodiesel‐diesel blend as alternate fuel in CI engine

AbstractThis study meticulously examined the impact of preheated tallow biodiesel on the performance and emission characteristics of a diesel engine. Employing a single‐cylinder, water‐cooled diesel engine configured with exhaust gas recirculation in this investigation, exhaust gas temperature (EGT) could be used to preheat the biodiesel, reducing its viscosity and density. This improvement in viscosity and density could enhance the injection process, which is often hindered by the higher density and viscosity of biodiesel compared with diesel fuel. The investigation achieved a peak preheat temperature of 70°C for the biodiesel, leading to notable improvements in brake thermal efficiency and brake power, particularly under high‐load conditions. A significant reduction in emissions was observed, with hydrocarbon and carbon monoxide levels decreasing by 46.87% and 50%, respectively, when using preheated biodiesel. To refine the engine's performance further, this study utilized response surface methodology (RSM) for the optimization of operational parameters, including injection timing, engine load, and biodiesel preheat temperatures. Optimal conditions were identified at an injection timing of 21° before top dead centre, a preheat temperature of 64°C, and an engine load of 45.45% for which output response was 18.68% brake thermal efficiency, 307°C EGT, 0.0247% vol. CO, 15.32 ppm hydrocarbons, and 131.37 ppm nitrogen oxides (NOx). The successful implementation of preheated tallow biodiesel signifies a crucial step forward in the pursuit of a more sustainable and efficient transportation industry. This advancement holds the promise of reducing reliance on traditional fossil fuels, thereby contributing to the global efforts towards achieving a more environmentally friendly energy landscape.

Spatial and temporal predictions of mosquito potential breeding sites and densities: integration of satellite imagery, in-situ data, and process-based modeling

Abstract. Dengue fever, primarily transmitted worldwide by the mosquito Aedes aegypti, poses significant public health challenges in tropical and subtropical regions. While effective vector control is crucial in the absence of reliable dengue vaccines, traditional control methods face obstacles like mosquito resistance to insecticides and a very high cost. By combining geospatial data, including satellite imagery, as descriptors, and entomological surveys as target variables in a Random Forest model, we predicted the number of potential mosquito breeding sites, derived the associated environmental carrying capacity for larvae, and used the Arbocarto process-based model to predict Ae.aegypti population densities in an urban region of French Guiana, South America. Our findings highlight that remote sensing data may help predict the number of potential breeding sites over urban areas. Our simulations indicate higher mosquito densities in urban residential areas and a strong spatial and temporal heterogeneity. These densities fluctuate according to intra-annual variations in temperature and precipitation, with higher densities associated with intermediate housing. A comparison with the conventional estimation of environmental carrying capacity for larvae in the current Arbocarto procedure highlights the advantages of our approach. Our study demonstrates the utility of integrating remote sensing with predictive modeling to enhance vector surveillance and control strategies, and provides a replicable approach for monitoring a dengue vector mosquito population in dynamic urban landscapes.