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1. Transposase-assisted target-site integration for efficient plant genome engineering

   https://doi.org/10.1038/s41586-024-07613-8  

   Liu, Peng; Panda, Kaushik; Edwards, Seth A; Swanson, Ryan; Yi, Hochul; Pandesha, Pratheek; Hung, Yu-Hung; Klaas, Gerald; Ye, Xudong; Collins, Megan V; et al (July 2024, Nature)

   The current technologies to place new DNA into specific locations in plant genomes are low frequency and error-prone, and this inefficiency hampers genome-editing approaches to develop improved crops. Often considered to be genome ‘parasites’, transposable elements (TEs) evolved to insert their DNA seamlessly into genomes. Eukaryotic TEs select their site of insertion based on preferences for chromatin contexts, which differ for each TE type. Here we developed a genome engineering tool that controls the TE insertion site and cargo delivered, taking advantage of the natural ability of the TE to precisely excise and insert into the genome. Inspired by CRISPR-associated transposases that target transposition in a programmable manner in bacteria, we fused the rice Pong transposase protein to the Cas9 or Cas12a programmable nucleases. We demonstrated sequence-specific targeted insertion (guided by the CRISPR gRNA) of enhancer elements, an open reading frame and a gene expression cassette into the genome of the model plant Arabidopsis. We then translated this system into soybean—a major global crop in need of targeted insertion technology. We have engineered a TE ‘parasite’ into a usable and accessible toolkit that enables the sequence-specific targeting of custom DNA into plant genomes. 

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2. Wave Generation by Flare-accelerated Ions and Implications for ³ He Acceleration

   https://doi.org/10.3847/1538-4357/ad217f  

   Fitzmaurice, A.; Drake, J. F.; Swisdak, M. (March 2024, The Astrophysical Journal)

   Abstract The waves generated by high-energy proton and alpha particles streaming from solar flares into regions of colder plasma are explored using particle-in-cell simulations. Initial distribution functions for the protons and alphas consist of two populations: an energetic, streaming population represented by an anisotropic (T_∥>T_⊥), one-sided kappa function and a cold, Maxwellian background population. The anisotropies and nonzero heat fluxes of these distributions destabilize oblique waves with a range of frequencies below the proton cyclotron frequency. These waves scatter particles out of the tails of the initial distributions along constant-energy surfaces in the wave frame. Overlap of the nonlinear resonance widths allows particles to scatter into near-isotropic distributions by the end of the simulations. The dynamics of³He are explored using test particles. Their temperatures can increase by a factor of nearly 20. Propagation of such waves into regions above and below the flare site can lead to heating and transport of³He into the flare acceleration region. The amount of heated³He that will be driven into the flare site is proportional to the wave energy. Using values from our simulations, we show that the abundance of³He driven into the acceleration region should approach that of⁴He in the corona. Therefore, waves driven by energetic ions produced in flares are a strong candidate to drive the enhancements of³He observed in impulsive flares. 

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3. Contrastive Learning and Cycle Consistency-Based Transductive Transfer Learning for Target Annotation

   https://doi.org/10.1109/TAES.2023.3337768  

   Sami, Shoaib Meraj; Hasan, Md Mahedi; Nasrabadi, Nasser M.; Rao, Raghuveer (January 2024, IEEE Transactions on Aerospace and Electronic Systems)

   Annotating automatic target recognition images is challenging; for example, sometimes there is labeled data in the source domain but no labeled data in the target domain. Therefore, it is essential to construct an optimal target domain classifier using the labeled information of the source domain images. For this purpose, we propose a transductive transfer learning (TTL) network consisting of an unpaired domain translation network, a pretrained source domain classifier, and a gradually constructed target domain classifier. We delve into the unpaired domain translation network, which simultaneously optimizes cycle consistency and modulated noise contrastive losses (MoNCE). Furthermore, the proposed hybrid CUT module integrated into the TTL network generates synthetic negative patches by noisy features mixup, and all the negative patches provide modulated weight into the NCE loss by considering similarity to the query. Apart from that, this hybrid CUT network considers query selection by entropy-based attention to specifying domain variants and invariant regions. The extensive analysis depicted that the proposed transductive network can successfully annotate civilian, military vehicles, and ship targets into the three benchmark ATR datasets. We further demonstrate the importance of each component of the TTL network through extensive ablation studies into the DSIAC dataset. 

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4. Effect of skull morphology on fox snow diving

   https://doi.org/10.1073/pnas.2321179121  

   Yuk, Jisoo; Pandey, Anupam; Park, Leena; Bemis, William E; Jung, Sunghwan (May 2024, Proceedings of the National Academy of Sciences)

   Certain fox species plunge-dive into snow to catch prey (e.g., rodents), a hunting mechanism called mousing. Red and arctic foxes can dive into snow at speeds ranging between 2 and 4 m/s. Such mousing behavior is facilitated by a slim, narrow facial structure. Here, we investigate how foxes dive into snow efficiently by studying the role of skull morphology on impact forces it experiences. In this study, we reproduce the mousing behavior in the lab using three-dimensional (3D) printed fox skulls dropped into fresh snow to quantify the dynamic force of impact. Impact force into snow is modeled using hydrodynamic added mass during the initial impact phase. This approach is based on two key facts: the added mass effect in granular media at high Reynolds numbers and the characteristics of snow as a granular medium. Our results show that the curvature of the snout plays a critical role in determining the impact force, with an inverse relationship. A sharper skull leads to a lower average impact force, which allows foxes to dive head-first into the snow with minimal tissue damage. 

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5. Solvent Interface Trapping as an Effective Technique to Fabricate Graphite-Nanomaterial Composite Thin Films

   https://doi.org/10.1557/adv.2017.621  

   Padmanabhan, Medini; Meyen, Rachel; Houghton, Kerri; John, Miles St. (January 2018, MRS Advances)

   ABSTRACT Natural graphite can be exfoliated into thin films by trapping it at the interface between water and heptane [S. J Woltornist, A. J. Oyer, J-M. Y. Carrillo, A.V. Dobrynin, and D.H. Adamson, ACS Nano 7 , 7062 (2013)]. In this work, we add functional elements into these graphitic thin films by introducing additives into the water phase prior to exfoliation. We report the successful incorporation of ZnO nanoparticles thereby enabling the composite films to act as effective ultraviolet photodetectors. In a similar manner, integration of silver nanowires is achieved, which results in an enhancement of the electrical conductivity of graphite. 

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