37495 research outputs found
Sort by
Optimizing Plant Nutrient Uptake: Cost Function Sensitivity Analysis of the FUN Model
No full textThis study explores the cost functions of the Fixation & Uptake of Nutrients (FUN) model, which aims to optimize the amount of carbon used when plants acquire their necessary nutrients from the soil to maximize nitrogen (N) and phosphorus (P) uptake while minimizing the carbon cost. Specifically, we aimed to quantify the sensitivity of FUN outputs to the parameters belonging to the cost of nitrogen and phosphorus uptake functions by arbuscular mycorrhizal and ectomycorrhizal fungi. We present three dimensions of sensitivity analysis: (1) adjusting all parameters at the same time; (2) keeping one parameter constant while varying the other; and, (3) assessing the individual impacts by reversing the direction of the held constant parameter. We validated outcome variations of modeled outputs against measured observations including parameters of plant-soil interactions such as soil temperature, carbon net primary production, evapotranspiration, root carbon, and nitrogen and phosphorus contents in leaves and soil. When analyzing the cost of resorption of leaf phosphorus, increasing the kR cost parameter, which represents the cost of resorption, decreased the coefficient of determination (R2) value, and the model’s predictions became lower than observed, with a larger residual spread; this introduced uncertainty in the predictions with a more negative bias and increased root mean square error. We ran an optimization function on the parameters but found that this did not significantly improve the model, indicating that the original parameterizations are robust against the available data. This study aligns with and builds upon previous research in the field, emphasizing the need to perform sensitivity analysis further to enhance predictive accuracy of plant nutrient uptake and corresponding impacts to carbon cycling
Allosteric Control Overcomes Steric Limitations for Neutralizing Antibodies Targeting Conserved Binding Epitopes of the SARS-CoV-2 Spike Protein: Exploring the Intersection of Binding, Allostery, and Immune Escape with a Multimodal Computational Approach
Get PDFUnderstanding the atomistic basis of multi-layer mechanisms employed by broadly reactive neutralizing antibodies of the SARS-CoV-2 spike protein without directly blocking receptor engagement remains an important challenge in coronavirus immunology. Class 4 antibodies represent an intriguing case: they target a deeply conserved, cryptic epitope on the receptor-binding domain yet exhibit variable neutralization potency across subgroups F1 (CR3022, EY6A, COVA1-16), F2 (DH1047), and F3 (S2X259). The molecular basis for this variability is not fully understood. Here, we employed a multi-modal computational approach integrating atomistic and coarse-grained molecular dynamics simulations, binding free energy calculations, mutational scanning, and dynamic network analysis to elucidate how these antibodies engage the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and influence its function. Our results reveal that neutralization efficacy arises from the interplay of direct interfacial interactions and allosteric effects. Group F1 antibodies (CR3022, EY6A, COVA1-16) primarily operate via classic allostery, modulating flexibility in RBD loop regions to indirectly interfere with the ACE2 receptor binding through long-range effects. Group F2 antibody DH1047 represents an intermediate mechanism, combining partial steric hindrance—through engagement of ACE2-critical residues T376, R408, V503, and Y508—with significant allosteric influence, facilitated by localized communication pathways linking the epitope to the receptor interface. Group F3 antibody S2X259 achieves potent neutralization through a synergistic mechanism involving direct competition with ACE2 and localized allosteric stabilization, albeit with potentially increased escape vulnerability. Dynamic network analysis identified a conserved “allosteric ring” within the RBD core that serves as a structural scaffold for long-range signal propagation, with antibody-specific extensions modulating communication to the ACE2 interface. These findings support a model where Class 4 neutralization strategies evolve through the refinement of peripheral allosteric connections rather than epitope redesign. This study establishes a robust computational framework for understanding the atomistic basis of neutralization activity and immune escape for Class 4 antibodies, highlighting how the interplay of binding energetics, conformational dynamics, and allosteric modulation governs their effectiveness against SARS-CoV-2
Unraveling Crop Nitrogen-Water Dynamics with Hyperspectral-Thermal Sensing in Northern Central Valley, California
Get PDFEnsuring global food security in the face of climate change requires optimizing crop water use and nutrient management. This study investigates the relationship between canopy nitrogen (N) and evapotranspiration (ET) across sunflower, rice, walnut, alfalfa, and plum crops using advanced remote sensing technologies. High-resolution hyperspectral data from NASAs Earth Surface Mineral Dust Source Investigation (EMIT) and thermal multispectral data from the Landsat-based OpenET system were analyzed over 1,135 km2 in California. Regression analysis revealed strong spatial association between canopy N and ET for sunflower (R2 = 0.82), rice (R2 = 0.71), and walnut (R2 = 0.68), with weaker associations for alfalfa (R2 = 0.38) and plums (R2 = 0.26) over the average of growing season. Temporal variations highlighted the high nitrogen efficiency of sunflower, rice, and walnut, demonstrating the capability of hyperspectral sensors to monitor nutrient-water dynamics effectively. These findings emphasize the potential of integrating hyperspectral and thermal data to enhance fertilizer and irrigation strategies. Furthermore, the study aligns with NASAs Surface Biology and Geology (SBG) mission, offering valuable insights into precision agriculture and sustainable crop management under changing climatic conditions
Assessing Functional Communication in Persons With Aphasia: A Scoping Review of Formal and Informal Measures
No full textBackground
The communicative effectiveness of persons with aphasia (PWA) has been assessed through a range of functional communication measures. However, variability in interpretations of what is covered by the term “functional communication” may have resulted in challenges to the implementation of appropriate and consistent patient-centred evaluations, with different measures focusing on subsets of the components of functional communication. Aims
This paper aims to examine the current literature on informal and formal evaluation of functional communication in PWA and to identify gaps in currently available assessment tools. Methods
This scoping review included studies published between 1965 and 2024 that assessed functional communication in PWA, excluding studies focused on non-aphasic populations or impairment-based assessments without real-world application. Systematic searches were conducted in PubMed, Embase, CINAHL, Scopus, and PsycINFO using predefined search terms. Of the 541 studies identified, 67 met the inclusion criteria after title/abstract and full-text screening. Measures were categorized as formal (standardized) or informal (non-standardized) and evaluated based on contextuality, multimodality, and interactiveness. Informal assessments also emphasized life participation, quality of life, augmentative alternative communication (AAC) strategies, conversational discourse, the informativeness and complexity of language use, and real-world communicative transactions. Main Contribution
In the 67 studies included in the literature review, 32 functional communication assessments were identified across the categories of informal and formal evaluation. Informal assessments (28) included patient-reported, clinician-reported, observer-reported, and performance-based outcome measures. Formal functional communication assessments (4) included systematically normed instruments provided to PWA under controlled conditions, yielding a diagnosis or level of specified functional communication capability. Of the reviewed informal and formal measures, a limited quantity met all criteria for a comprehensive assessment of functional communication in aphasia, namely, being contextual, multimodal, and interactive. Conclusions
Existing assessments reveal gaps in the comprehensive evaluation of functional communication. The findings emphasize the need for standardized, multimodal, and context-sensitive tools that better reflect the dynamic, real-world communicative needs of PWA
P–12 District Equity “Shutdown”: Equity Directors’ Experiences Amid Anti-Equity Organizing, 2020–2022
No full textThis article examines local experiences of the national attack on district equity work intended to better support Students of Color and LGBTQ+ students over the 2020–2022 school years. Drawing on theory on zones of mediation and interviews with over 70 district “equity directors” (EDs) nationally, I analyze how together national, state, and local pressure led to district equity “shutdown.” Forms of district equity shutdown included censoring equity-focused communication and language, eliminating district equity-focused programming or personnel, and restricting books and learning resources, with 40% of EDs reporting at least one form of district equity shutdown
Dictators and Lying Dictators: An Experimental Investigation of Preference Based-Group Biases in Chinese and American Interactions
No full textThis study examines preference-based behavioral biases in social interactions between two distinct communities: students from Chapman University in the United States and Wuhan University in China. Using controlled experiments, participants interacted within or across communities in Dictator games. Two versions of the Dictator game were used: one where decisions were observable by both the experimenter and the recipient, and another where allocators could misreport outcomes with plausible deniability. Results revealed unexpected patterns, including similar allocation distributions across communities in the transparent task, and differing behaviors in the misreporting task, with Chapman allocators being more generous to out-group members and Wuhan allocators choosing more selfishly. The study challenges traditional theories of in-group favoritism and highlights the role of cultural differences and image concerns in decision-making. Findings contribute to understanding cross-cultural interactions, particularly in the context of increasing global connectivity
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1002/thumbnail.jp
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1007/thumbnail.jp
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1034/thumbnail.jp
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1041/thumbnail.jp