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1. T1 and T2 measurements across multiple 0.55T MRI systems using open‐source vendor‐neutral sequences

   https://doi.org/10.1002/mrm.30281  

   Keenan, Kathryn E; Tasdelen, Bilal; Javed, Ahsan; Ramasawmy, Rajiv; Rizzo, Rudy; Martin, Michele N; Stupic, Karl F; Seiberlich, Nicole; Campbell‐Washburn, Adrienne E; Nayak, Krishna S (January 2025, Magnetic Resonance in Medicine)

   Abstract PurposeTo compare T1 and T2 measurements across commercial and prototype 0.55T MRI systems in both phantom and healthy participants using the same vendor‐neutral pulse sequences, reconstruction, and analysis methods. MethodsStandard spin echo measurements and abbreviated protocol measurements of T1, B1, and T2 were made on two prototype 0.55 T systems and two commercial 0.55T systems using an ISMRM/NIST system phantom. Additionally, five healthy participants were imaged at each system using the abbreviated protocol for T1, B1, and T2 measurement. The phantom measurements were compared to NMR‐based reference measurements to determine accuracy, and both phantom and in vivo measurements were compared to assess reproducibility and differences between the prototype and commercial systems. ResultsVendor‐neutral sequences were implemented across all four systems, and the code for pulse sequences and reconstruction is freely available. For participants, there was no difference in the mean T1 and T2 relaxation times between the prototype and commercial systems. In the phantom, there were no significant differences between the prototype and commercial systems for T1 and T2 measurements using the abbreviated protocol. ConclusionQuantitative T1 and T2 measurements at 0.55T in phantom and healthy participants are not statistically different across the prototype and commercial systems. 

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2. A separation theorem for simple theories

   https://doi.org/10.1090/tran/8513  

   Malliaris, M.; Shelah, S. (April 2022, Transactions of the American Mathematical Society)

   This paper builds model-theoretic tools to detect changes in complexity among the simple theories. We develop a generalization of dividing, called shearing, which depends on a so-called context c. This leads to defining c-superstability, a syntactical notion, which includes supersimplicity as a special case. The main result is a separation theorem showing that for any countable context and any two theories T1, T2, such that T1 is c-superstable and T2 is c-unsuperstable, and for arbitrarily large mu, it is possible to build models of any theory interpreting both T1 and T2 whose restriction to tau(T1) is mu-saturated and whose restriction to tau(T2) is not aleph1-saturated. (This suggests “c-superstable” is really a dividing line.) The proof uses generalized Ehrenfeucht-Mostowski models, and along the way, we clarify the use of these techniques to realize certain types while omitting others. In some sense, shearing allows us to study the interaction of complexity coming from the usual notion of dividing in simple theories and the more combinatorial complexity detected by the general definition. This work is inspired by our recent progress on Keisler’s order, but does not use ultrafilters, rather aiming to build up the internal model theory of these classes. https://doi.org/10.1090/tran/8513 

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3. Two-Level Private Information Retrieval

   https://doi.org/10.1109/ISIT45174.2021.9518167  

   Zhou, Ruida; Tian, Chao; Sun, Hua; Plank, James S. (July 2021, 2021 IEEE International Symposium on Information Theory (ISIT))

   null (Ed.)

   In the conventional robust T -colluding private information retrieval (PIR) system, the user needs to retrieve one of the possible messages while keeping the identity of the requested message private from any T colluding servers. Motivated by the possible heterogeneous privacy requirements for different messages, we consider the ( N,T1:K1,T2:K2 ) two-level PIR system, where K1 messages need to be retrieved privately against T1 colluding servers, and all the messages need to be retrieved privately against T2 colluding servers where T2≤T1 . We obtain a lower bound to the capacity by proposing a novel coding scheme, namely the non-uniform successive cancellation scheme. A capacity upper bound is also derived. The gap between the upper bound and the lower bound is analyzed, and shown to vanish when T1=T2 . 

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4. Programmable Nuclear-Spin Dynamics in Ti(IV) Coordination Complexes

   https://doi.org/10.1021/acs.inorgchem.0c00244  

   Johnson, Spencer H.; Jackson, Cassidy E.; Zadrozny, Joseph M. (April 2020, Inorganic Chemistry)

   Interstitial patterning of nuclear spins is a nascent design principle for controlling electron spin superposition lifetimes in open-shell complexes and solid-state defects. Herein we report the first test of the impact of the patterning principle on ligand-based nuclear spin dynamics. We test how substitutional patterning of 1H and 79/81Br nuclear spins on ligands modulates proton nuclear spin dynamics in the ligand shell of metal complexes. To do so, we studied the 1H nuclear magnetic resonance relaxation times (T1 and T2) of a series of eight polybrominated catechol ligands and six complexes formed by coordination of the ligands to a Ti(IV) ion. These studies reveal that 1H T1 values can be enhanced in the individual ligands by a factor of 4 (from 10.8(3) to 43(5) s) as a function of substitution pattern, reaching the maximum value for 3,4,6-tribromocatechol. The T2 for 1H is also enhanced by a factor of 4, varying by ∼14 s across the series. When complexed, the impact of the patterning design strategy on nuclear spin dynamics is amplified and 1H T1 and T2 values vary by over an order of magnitude. Importantly, the general trends observed in the ligands also match those when complexed. Hence, these results demonstrate a new design principle to control 1H spin dynamics in metal complexes through pattern-based design strategies in the ligand shell. 

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5. Promoting Diverse Youth’s Career Development through Informal Science Learning: The Role of Inclusivity and Belonging

   https://doi.org/10.1007/s10964-022-01694-2  

   Zhao, Mengya; Mathews, Channing J.; Mulvey, Kelly Lynn; Hartstone-Rose, Adam; McGuire, Luke; Hoffman, Adam J.; Winterbottom, Mark; Joy, Angelina; Law, Fidelia; Balkwill, Frances; et al (February 2023, Journal of Youth and Adolescence)

   Abstract Little research has examined the associations between perceived inclusivity within informal science learning sites, youth program belonging and perceptions of program career preparation. This study explored relations between these factors at three timepoints (T1 = start of program, T2 = 3 months and T3 = 12 months after start). Participants were a diverse sample of 209 adolescents participating in STEM youth programs within informal science learning sites situated in the United States and United Kingdom (70% females: M age  = 15.27, SD age  = 1.60), with 53.1% British and 64.1% non-White. Path analysis revealed that only perceptions of inclusivity for own social identity group (i.e., gender, ethnicity) at T1 were associated with T2 STEM youth program belonging. There was a significant indirect effect of T1 perceptions of inclusivity for one’s own social identity groups on T3 perceptions of program career preparation via T2 program belonging. This study highlights that, over time, perceptions of inclusivity around youth’s own social identity groups (i.e., gender and ethnicity/culture) are related to a sense of youth program belonging, which in turn is later associated with perceptions of program career preparation. 

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