Optimally Distributed Receiver Placements Versus an Environmentally Aware Source: New England Shelf Break Acoustics Signals and Noise Experiment

This article describes the results of the Spring of 2021 New England Shelf Break Acoustics (NESBA) Signals and Noise experiment as they pertain to the optimization of a field of passive receivers versus an environmentally aware source with end-state goals. A discrete optimization has been designed and used to demonstrate providing an acoustic system operator with actionable guidance relating to optimally distributed receiver locations and depths and likely mean source detection times and associated uncertainties as a function of source and receiver levels of environmental awareness. The uncertainties considered here are those due to the imperfect spatial and temporal sensing of the water column, ambient noise (AN), and the seabed, and the impact this has on ocean forecasting and acoustic performance prediction accuracy. As a part of the NESBA experiment, high-resolution (1 km spatial) regional Navy Coastal Ocean Model ensemble forecasts were generated to capture oceanographic variability and uncertainty. Passive AN-based seabed measurements were conducted to estimate seabed properties including variability and uncertainty. Extensive AN and conductivity, temperature, and depth measurements were also conducted. In this article, operationally relevant metrics are employed to estimate the potential value-added of optimal receiver location and depth placements as a function of source end-state goals and assumed level of environmental awareness. A concept for generating stochastic acoustic prediction metrics and associated optimally distributed receiver locations and depths in an operational environment is proposed

Brightness and mass accretion rate evolution during the 2022 burst of EX~Lupi

EX Lupi is the prototype by which EXor-type outbursts were defined. It has experienced multiple accretion-related bursts and outbursts throughout the last decades, whose study have greatly extended our knowledge about the effects of these types of events. This star experienced a new burst in 2022. We used multi-band photometry to create color-color and color-magnitude diagrams to exclude the possibility that the brightening could be explained by a decrease in extinction. We obtained VLT/X-shooter spectra to determine the Lacc and Macc during the peak of the burst and after its return to quiescence using 2 methods: empirical relationships between line luminosity and Lacc, and a slab model of the whole spectrum. We examined the 130 year light curve of EX Lupi to provide statistics on the number of outbursts experienced during this period of time. Our analysis of the data taken during the 2022 burst confirmed that a change in extinction is not responsible for the brightening. Our two approaches in calculating the Macc were in agreement, and resulted in values that are 2 orders of magnitude above what had previously been estimated, thus suggesting that EX Lupi is a strong accretor even when in quiescence. We determined that in 2022 March the Macc increased by a factor of 7 with respect to the quiescent level. We also found hints that even though the Macc had returned to almost its pre-outburst levels, certain physical properties of the gas had not returned to the quiescent values. We found that the mass accreted during this three month event was 0.8 lunar masses, which is approximately half of what is accreted during a year of quiescence. We calculated that if EX Lupi remains as active as it has been for the past 130 years, during which it has experienced at least 3 outbursts and 10 bursts, then it will deplete the mass of its circumstellar material in less than 160000 yr

Ocean Ensemble-Enabled Stochastic Acoustic Prediction with Operational Metrics: New England Shelf Break Acoustics Signals and Noise Experiment

This article describes the results of the New England shelf break acoustics (NESBA) experiment as they pertain to acoustic prediction and the quantification of associated uncertainties in relevant operational metrics. The uncertainties considered here are those due to the imperfect sensing of the water column, ambient noise (AN), and the seabed, and the impact this has on ocean forecasting and acoustic performance prediction accuracy. Operational metrics are designed to provide an acoustic system operator with actionable guidance relating to likely mean source detection ranges and associated uncertainties with specific guidance on the degree to which specific environmental factors (e.g., oceanography, seabed, and ambient noise) contribute to the predicted uncertainty levels. High-resolution regional Navy Coastal Ocean Model (NCOM) ensemble forecasts were generated to capture oceanographic variability and uncertainty. Passive ambient noise-based seabed measurements were conducted to estimate seabed properties. Extensive AN and conductivity, temperature, and depth (CTD) measurements were also conducted. Measurement-based versus model-based acoustic prediction metrics are compared as an initial validation of the underlying methodology. It is shown that Global Hybrid Coordinate Ocean Model (HYCOM) ocean forecasts with databased AN and seabed parameters result in very large metric uncertainties, while leveraging high-resolution NCOM with ensembles and in situ AN and seabed measurements can result in substantially reduced uncertainties. It is also demonstrated that improved ocean modeling and sensing can be leveraged to determine the best receiver depth, associated uncertainty levels, and uncertainty drivers. An operational concept for generating acoustic prediction metrics and associated operator environmental sensing guidance is proposed

Chemicals Inducing Seed Germination and Early Seedling Development

Seed germination and early seedling development are essential events in the plant life cycle that are controlled largely by the interplay and cross-talk between several plant hormones. Recently, major progress has been achieved in the elucidation at the molecular level of the signalling of these phytohormones. In this review, we summarise the data for the most promising classes of compounds, which could find potential agronomic applications for promoting seed germination and early seedling development even under abiotic stress conditions. Structural modifications of plant hormones are required to improve their biological performance and their specificity to allow commercial application