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1. Arg302 governs the pK _a of Glu325 in LacY

   https://doi.org/10.1073/pnas.1820744116  

   Grytsyk, Natalia; Santos Seiça, Ana Filipa; Sugihara, Junichi; Kaback, H. Ronald; Hellwig, Petra (February 2019, Proceedings of the National Academy of Sciences)

   Lactose permease is a paradigm for the major facilitator superfamily, the largest family of ion-coupled membrane transport proteins known at present. LacY carries out the coupled stoichiometric symport of a galactoside with an H⁺, using the free energy released from downhill translocation of H⁺to drive accumulation of galactosides against a concentration gradient. In neutrophilicEscherichia coli, internal pH is kept at ∼7.6 over the physiological range, but the apparent pK (pK^app) for galactoside binding is 10.5. Surface-enhanced infrared absorption spectroscopy (SEIRAS) demonstrates that the high pK_ais due to Glu325 (helix X), which must be protonated for LacY to bind galactoside effectively. Deprotonation is also obligatory for turnover, however. Here, we utilize SEIRAS to study the effect of mutating residues in the immediate vicinity of Glu325 on its pK_a. The results are consistent with the idea that Arg302 (helix IX) is important for deprotonation of Glu325. 

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2. Analysis of $$ {\Lambda}_b^0 $$ → pK−μ+μ− decays

   https://doi.org/10.1007/JHEP12(2024)147  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (December 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> The differential branching fraction and angular coefficients of$$ {\Lambda}_b^0 $$ ${\Lambda }_b^0$→pK⁻μ⁺μ⁻decays are measured in bins of the dimuon mass squared and dihadron mass. The analysis is performed using a data set corresponding to 9 fb⁻¹of integrated luminosity collected with the LHCb detector between 2011 and 2018. The data are consistent with receiving contributions from a mixture of Λ resonances with different spin-parity quantum numbers. The angular coefficients show a pattern of vector-axial vector interference that is a characteristic of the type of flavour-changing neutral-current transition relevant for these decays. 

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3. Ionization waves in the PK-4 direct current neon discharge

   https://doi.org/10.1088/1361-6595/abb955  

   Hartmann, Peter; Rosenberg, Marlene; Juhasz, Zoltan; Matthews, Lorin S; Sanford, Dustin L.; Vermillion, Katrina; Reyes, Jorge Carmona; Hyde, Truell W (November 2020, Plasma Sources Science and Technology)

   null (Ed.)

   The PK-4 system is a micro-gravity dusty plasma experiment currently in operation on-board the International Space Station. The experiment utilizes a long DC discharge in neon or argon gases. We apply our 2D particle-in-cell with Monte Carlo collisions discharge simulation to compute local plasma parameters that serve as input data for future dust dynamics models. The simulation includes electrons, Ne+ ions, and Nem metastable atoms in neon gas and their collisions at solid surfaces including secondary electron emission and glass wall charging. On the time scale of the on-board optical imaging, the positive column appears stable and homogeneous. On the other hand, our simulations show that on microsecond time scales the positive column is highly inhomogeneous: ionization waves with phase velocities in the range between 500 m s−1 and 1200 m s−1 dominate the structure. In these waves, the electric field and charged particle densities can reach amplitudes up to 10 times of their average value. Our experiments on ground-based PK-4 replica systems fully support the numerical findings. In the experiment, the direction of the DC current can be alternated, which has been found to favor dust particle chain formation. We discuss possible mechanisms for how the highly oscillatory plasma environment contributes to the dust particle chain formation. 

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4. Independent Set on Pk-Free Graphs in Quasi-Polynomial Time

   https://doi.org/10.1109/FOCS46700.2020.00063  

   Gartland, Peter; Lokshtanov, Daniel (November 2020, 61st IEEE Annual Symposium on Foundations of Computer Science)
5. Integrating STEM and Computing in PK-12: Operationalizing Computational Thinking for STEM Learning and Assessment

   https://doi.org/https://doi.dx.org/10.22318/icls2020.1479 https://repository.isls.org//handle/1/6353  

   Grover, S.; Biswas, G.; Dickes, A.; Farris, A.; Sengupta, P.; Covitt, B.; Gunckel, K.; Berkowitz, A.; Moore, J.; Irgens, G. A.; et al (June 2020, The Interdisciplinarity of the Learning Sciences, 14th International Conference of the Learning Sciences (ICLS) 2020)

   Gresalfi, M.; Horn, I. S. (Ed.)

   There is broad belief that preparing all students in preK-12 for a future in STEM involves integrating computing and computational thinking (CT) tools and practices. Through creating and examining rich “STEM+CT” learning environments that integrate STEM and CT, researchers are defining what CT means in STEM disciplinary settings. This interactive session brings together a diverse spectrum of leading STEM researchers to share how they operationalize CT, what integrated CT and STEM learning looks like in their curriculum, and how this learning is measured. It will serve as a rich opportunity for discussion to help advance the state of the field of STEM and CT integration. 

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