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We consider the competitive dynamics of two viral strains using compartmental epidemiological models that incorporate temporary cross-immunity with a discrete time delay, and are calibrated using wastewater surveillance data. We identify biological conditions for strain coexistence based on the strain-specific basic reproduction number $$\mathcal{R}_i$$. For instance, $$\mathcal{R}_1>\mathcal{R}_2$$ enables strain 1 persistence. We also demonstrate that immune enhancement of infection ($$\epsilon>1$$) is necessary for the establishment of a less fit strain ($$\mathcal{R}_2<1<\mathcal{R}_1$$). We define parameter thresholds that induce stability switches that lead to complex dynamical behaviors such as the emergence of limit cycles around strain 1's equilibrium. In addition, we perform data fitting, simulations, and global sensitivity analysis to evaluate the influence of the recovered class on wastewater viral signals. Our results illustrate that infection-immune dynamics can naturally give rise to the multi-wave epidemic patterns and support the integration of dynamical models in wastewater-based epidemiology. 

We consider the competitive dynamics of two viral strains using compartmental epidemiological models that incorporate temporary cross-immunity with a discrete time delay, and are calibrated using wastewater surveillance data. We identify biological conditions for strain coexistence based on the strain-specific basic reproduction number $$\mathcal{R}_i$$. For instance, $$\mathcal{R}_1>\mathcal{R}_2$$ enables strain 1 persistence. We also demonstrate that immune enhancement of infection ($$\epsilon>1$$) is necessary for the establishment of a less fit strain ($$\mathcal{R}_2<1<\mathcal{R}_1$$). We define parameter thresholds that induce stability switches that lead to complex dynamical behaviors such as the emergence of limit cycles around strain 1's equilibrium. In addition, we perform data fitting, simulations, and global sensitivity analysis to evaluate the influence of the recovered class on wastewater viral signals. Our results illustrate that infection-immune dynamics can naturally give rise to the multi-wave epidemic patterns and support the integration of dynamical models in wastewater-based epidemiology. 

Norovirus is a leading cause of gastroenteritis globally, yet its true infection burden in the community remains poorly understood due to widespread asymptomatic transmission and underreporting. Wastewater-based surveillance is a promising approach for tracking infection trends, but methods for mechanistically linking wastewater viral concentrations to infection dynamics remain limited. Here, we developed a mechanistic SEIR-V framework to infer community-level norovirus transmission dynamics from wastewater data by jointly modeling disease transmission, viral shedding kinetics, and wastewater viral load. We leveraged temporal fecal shedding data from a controlled human challenge study and systematic literature review to parameterize symptom-specific shedding profiles and integrate them into the framework. Applied to wastewater data from four treatment plants in El Paso, Texas, the model showed consistent agreement between out-of-sample predictions and observed wastewater viral load across sewersheds, while generating model-inferred temporal infection dynamics across disease compartments. Sensitivity analysis further showed that wastewater viral load was influenced by transmission, shedding, and viral loss parameters, whereas inferred infection dynamics were primarily influenced by transmission rate and infectious duration. This work provides a mechanistic wastewater modeling framework to infer norovirus transmission dynamics and could support proactive public health surveillance, particularly for pathogens with high asymptomatic transmission and limited clinical reporting. 

Abstract An overview is presented of our current understanding and open questions related to magnetic reconnection in solar flares and the near-sun (within around 20$$R_{s}$$ $R_s$ ) solar wind. The solar-flare-related topics include the mechanisms that facilitate fast energy release and that control flare onset, electron energization, ion energization and abundance enhancement, electron and ion transport, and flare-driven heating. Recent observations and models suggesting that interchange reconnection of multipolar magnetic fields within coronal holes could provide the energy required to drive the fast solar wind are also discussed. Recentin situobservations that reconnection in the heliospheric current sheet close to the sun drives energetic ions are also presented. The implications ofin situobservations of reconnection in the Earth space environment for understanding flares are highlighted. Finally, the impact of emerging computational and observational tools for understanding flare dynamics are discussed. 

ABSTRACT IntroductionCurcumin is a naturally occurring compound with anti‐inflammatory, cholesterol‐lowering, antidiabetic, and antioxidant properties. Curcumin can be biosynthesized in microbial hosts despite being found natively inCurcuma longaroots. ObjectivesIt is unclear whether curcumin is transported out of microbial cells, binds to the inner or outer cell membrane, or accumulates inside. This study aims to gain a better understanding of curcumin's behavior after its formation in the host, which could lead to the development of new approaches to improve curcumin production. Material and MethodsAdvanced imaging techniques, including SEM, TEM, SHS, and TPF, were utilized to understand the behavior of curcumin within and outside of engineeredEscherichia colicells. ResultsCurcumin was biosynthesized from ferulic acid in engineeredE. coliBL21(DE3) by coexpressing 4‐coumarate: CoA ligase and curcuminoid synthase. Second harmonic scattering (SHS) spectroscopy experiments utilized curcumin as a probe to investigate the surface binding of curcumin onto livingE. colicells with experimentally determined adsorption free energy,ΔG, values of −14.0 kcal/mol. By employing second harmonic and two‐photon fluorescence imaging methods, the spatial distribution of curcumin aggregates was determined. Electron microscopy images revealed the presence of curcumin aggregates within the cells, at the surface, and in the media. ConclusionThese experiments demonstrate that curcumin biosynthesis from ferulic acid leads to significant product aggregation within the cells, which could ultimately halt production by inducing cell death. Understanding the localization, transport, and removal of curcumin is crucial in developing more efficient biosynthetic pathways to enhance its production in microbial systems. 

Today's robotic laboratories for drones are housed in a large room. At times, they are the size of a warehouse. These spaces are typically equipped with permanent devices to localize the drones, e.g., Vicon Infrared cameras. Significant time is invested to fine-tune the localization apparatus to compute and control the position of the drones. One may use these laboratories to develop a 3D multimedia system with miniature sized drones configured with light sources. As an alternative, this brave new idea paper envisions shrinking these room-sized laboratories to the size of a cube or cuboid that sits on a desk and costs less than 10K dollars. The resulting Dronevision (DV) will be the size of a 1990s Television. In addition to light sources, its Flying Light Specks (FLSs) will be network-enabled drones with storage and processing capability to implement decentralized algorithms. The DV will include a localization technique to expedite development of 3D displays. It will act as a haptic interface for a user to interact with and manipulate the 3D virtual illuminations. It will empower an experimenter to design, implement, test, debug, and maintain software and hardware that realize novel algorithms in the comfort of their office without having to reserve a laboratory. In addition to enhancing productivity, it will improve safety of the experimenter by minimizing the likelihood of accidents. This paper introduces the concept of a DV, the research agenda one may pursue using this device, and our plans to realize one. 

Abstract We report observations of direct evidence of energetic protons being accelerated above ∼400 keV within the reconnection exhaust of a heliospheric current sheet (HCS) crossing by NASA’s Parker Solar Probe (PSP) at a distance of ∼16.25 solar radii (R_s) from the Sun. Inside the exhaust, both the reconnection-generated plasma jet and the accelerated protons up to ∼400 keV propagated toward the Sun, unambiguously establishing their origin from HCS reconnection sites located antisunward of PSP. Within the core of the exhaust, PSP detected stably trapped energetic protons up to ∼400 keV, which is ≈1000 times greater than the available magnetic energy per particle. The differential energy spectrum of the accelerated protons behaved as a pure power law with spectral index of ∼−5. Supporting simulations using thekglobalmodel suggest that the trapping and acceleration of protons up to ∼400 keV in the reconnection exhaust are likely facilitated by merging magnetic islands with a guide field between ∼0.2 and 0.3 of the reconnecting magnetic field, consistent with the observations. These new results, enabled by PSP’s proximity to the Sun, demonstrate that magnetic reconnection in the HCS is a significant new source of energetic particles in the near-Sun solar wind. Our findings of in situ particle acceleration via magnetic reconnection at the HCS provide valuable insights into this fundamental process, which frequently converts the large magnetic field energy density in the near-Sun plasma environment and may be responsible for heating the Sun’s atmosphere, accelerating the solar wind, and energizing charged particles to extremely high energies in solar flares.