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1. Hybrid Timestamping Using Crystal and RC Oscillators for Shock-Resistant Precision

   https://doi.org/10.1109/TVLSI.2025.3544410  

   Hamed, Ehab A; Carichner, Gordy; Green, Delbert A; Kim, Hun-Seok; Lee, Inhee (July 2025, IEEE Transactions on Very Large Scale Integration (VLSI) Systems)
2. Penicillin-binding protein redundancy in Bacillus subtilis enables growth during alkaline shock

   https://doi.org/10.1128/aem.00548-23  

   Mitchell, Stephanie L.; Kearns, Daniel B.; Carlson, Erin E. (December 2023, Applied and Environmental Microbiology)

   Bose, Arpita (Ed.)

   ABSTRACT Penicillin-binding proteins (PBPs) play critical roles in cell wall construction, cell shape maintenance, and bacterial replication. Bacteria maintain a diversity of PBPs, indicating that despite their apparent functional redundancy, there is differentiation across the PBP family. Apparently-redundant proteins can be important for enabling an organism to cope with environmental stressors. In this study, we evaluated the consequence of environmental pH on PBP enzymatic activity inBacillus subtilis. Our data show that a subset of PBPs inB. subtilischange activity levels during alkaline shock and that one PBP isoform is rapidly modified to generate a smaller protein (i.e., PBP1a to PBP1b). Our results indicate that a subset of the PBPs are favored for growth under alkaline conditions, while others are readily dispensable. Indeed, we found that this phenomenon could also be observed inStreptococcus pneumoniae, implying that it may be generalizable across additional bacterial species and further emphasizing the evolutionary benefit of maintaining many, seemingly-redundant periplasmic enzymes. IMPORTANCEMicrobes adapt to ever-changing environments and thrive over a vast range of conditions. While bacterial genomes are relatively small, significant portions encode for “redundant” functions. Apparent redundancy is especially pervasive in bacterial proteins that reside outside of the inner membrane. While conditions within the cytoplasm are carefully controlled, those of the periplasmic space are largely determined by the cell’s exterior environment. As a result, proteins within this environmentally exposed region must be capable of functioning under a vast array of conditions, and/or there must be several similar proteins that have evolved to function under a variety of conditions. This study examines the activity of a class of enzymes that is essential in cell wall construction to determine if individual proteins might be adapted for activity under particular growth conditions. Our results indicate that a subset of these proteins are preferred for growth under alkaline conditions, while others are readily dispensable. 

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3. In Situ Observations of Preferential Pickup Ion Heating at an Interplanetary Shock

   https://doi.org/10.1103/PhysRevLett.121.075102  

   Zirnstein, E. J.; McComas, D. J.; Kumar, R.; Elliott, H. A.; Szalay, J. R.; Olkin, C. B.; Spencer, J.; Stern, S. A.; Young, L. A. (August 2018, Physical Review Letters)
4. Substorm‐Time Ground d B / d t Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study

   https://doi.org/10.1029/2023SW003767  

   Oliveira, Denny M; Weygand, James M; Coxon, John C; Zesta, Eftyhia (March 2024, Space Weather)

   Abstract In this study, we investigate the effects caused by interplanetary (IP) shock impact angles on the subsequent grounddB/dtvariations during substorms. IP shock impact angles have been revealed as a major factor controlling the subsequent geomagnetic activity, meaning that shocks with small inclinations with the Sun‐Earth line are more likely to trigger higher geomagnetic activity resulting from nearly symmetric magnetospheric compressions. Such field variations are linked to the generation of geomagnetically induced currents (GICs), which couple to artificial conductors on the ground leading to deleterious consequences. We use a sub‐set of a shock data base with 237 events observed in the solar wind at L1 upstream of the Earth, and large arrays of ground magnetometers at stations located in North America and Greenland. The spherical elementary current system methodology is applied to the geomagnetic field data, and field‐aligned‐like currents in the ionosphere are derived. Then, such currents are inverted back to the ground anddB/dtvariations are computed. Geographic maps are built with these field variations as a function of shock impact angles. The main findings of this investigation are: (a) typicaldB/dtvariations (5–10 nT/s) are caused by shocks with moderate inclinations; (b) the more frontal the shock impact, the more intense and the more spatially defined the ionospheric current amplitudes; and (c) nearly frontal shocks trigger more intensedB/dtvariations with larger equatorward latitudinal expansions. Therefore, the findings of this work provide new insights for GIC forecasting focusing on nearly frontal shock impacts on the magnetosphere. 

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5. R1 retrotransposons in the nucleolar organizers of Drosophila melanogaster are transcribed by RNA polymerase I upon heat shock

   https://doi.org/10.1080/21541264.2018.1506682  

   Raje, Himanshu S.; Lieux, Molly E.; DiMario, Patrick J. (May 2018, Transcription)