Magnetoelastic standing waves induced in UO2 by microsecond magnetic field pulses

Magnetoelastic dilatometry of the piezomagnetic antiferromagnet UO2 was performed via the fiber Bragg grating method in magnetic fields up to 150 T generated by a single-turn coil setup. We show that in microsecond timescales, pulsed-magnetic fields excite mechanical resonances at temperatures ranging from 10 to 300 K, in the paramagnetic as well as within the robust antiferromagnetic state of the material. These resonances, which are barely attenuated within the 100-µs observation window, are attributed to the strong magnetoelastic coupling in UO2 combined with the high crystalline quality of the single crystal samples. They compare well with mechanical resonances obtained by a resonant ultrasound technique and superimpose on the known nonmonotonic magnetostriction background. A clear phase shift of π in the lattice oscillations is observed in the antiferromagnetic state when the magnetic field overcomes the piezomagnetic switch field Hc=−18 T. We present a theoretical argument that explains this unexpected behavior as a result of the reversal of the antiferromagnetic order parameter at Hc.

Meta-evaluation of Conversational Search Evaluation Metrics

Conversational search systems, such as Google assistant and Microsoft Cortana, enable users to interact with search systems in multiple rounds through natural language dialogues. Evaluating such systems is very challenging, given that any natural language responses could be generated, and users commonly interact for multiple semantically coherent rounds to accomplish a search task. Although prior studies proposed many evaluation metrics, the extent of how those measures effectively capture user preference remain to be investigated. In this article, we systematically meta-evaluate a variety of conversational search metrics. We specifically study three perspectives on those metrics: (1) reliability : the ability to detect “actual” performance differences as opposed to those observed by chance; (2) fidelity : the ability to agree with ultimate user preference; and (3) intuitiveness : the ability to capture any property deemed important: adequacy, informativeness, and fluency in the context of conversational search. By conducting experiments on two test collections, we find that the performance of different metrics vary significantly across different scenarios, whereas consistent with prior studies, existing metrics only achieve weak correlation with ultimate user preference and satisfaction. METEOR is, comparatively speaking, the best existing single-turn metric considering all three perspectives. We also demonstrate that adapted session-based evaluation metrics can be used to measure multi-turn conversational search, achieving moderate concordance with user satisfaction. To our knowledge, our work establishes the most comprehensive meta-evaluation for conversational search to date.

Vlogging as a Tool in the Self-Reflective Journey: Professional Identity Development as a Space Between

The authors present an interpretative phenomenological analysis (IPA) case study used to uncover the meaning-making system of professional identity development experienced by a graduate student completing a two-semester school counseling internship. The intern engaged in critical self-reflections as weekly vloggings, which are single-turn video monologs. The rigor of IPA allowed the researchers to explore the intern’s personal reflexivity as a space between what the intern was doing and his process of becoming a professional. The super-ordinate theme that emerged from the analysis in this case study was connecting the dots. . . it’s all about the kids. Findings from this research have implications in higher education and professional studies for creating a transformative learning environment and engaging individuals in the professional identity development process.

Nanomolar, noncovalent antagonism of hedgehog cholesterolysis: exception to the irreversibility rule for protein autoprocessing inhibition.

HHedgehog (Hh) signaling ligands undergo carboxy terminal sterylation through specialized autoprocessing, called cholesterolysis. Sterylation is brought about intramolecularly in a single turn-over by an enzymatic domain, called HhC. HhC is found in precursor Hh proteins only. Through cholesterolysis, HhC is cleaved from the precursor. Attempts to identify molecules that inhibit intramolecular cleavage/sterylation activity of HhC have resulted in antagonists that bind HhC irreversibly through covalent mechanisms, as is commonplace for protein autoprocessing inhibitors. Here we report an exception to the irreversibility rule for protein autoprocessing inhibition. Using a FRET-based activity assay for HhC, we screened a focused library of sterol-like analogs for HhC cholesterolysis inhibitors. We identified and validated four structurally related noncovalent inhibitors, which were then used for SAR studies. The most effective derivative, tBT-HBT, binds HhC reversibly with an IC50 of 300 nM. An allosteric binding site for tBT-HBT, encompassing interactions from the two subdomains of HhC, is suggested by kinetic analysis, mutagenesis studies, and photoaffinity labeling. A striking resemblance is found between the inhibitors described here and a family of noncovalent, allosteric activators of HhC, which we described previously. The inhibitor/activator duality appears to be mediated by the same allosteric site, which displays sensitivity to subtle differences in the structure of a heterocycle substituent on the effector molecule.

L2 Syntactic Alignment in the Reading-Writing Integrated Continuation Task: Evidence From Chinese EFL Learners’ Description of Motion Events

This study investigated how the mode in which the reading-writing integrated continuation task was conducted modulates the effects of second language (L2) syntactic alignment, through the English motion event construction with manner verbs. Ninety Chinese students were assigned to either of the two experimental groups or a control group, and they all experienced a pretest, an alignment phase and a posttest. In the alignment phase, the two experimental groups completed a reading-writing integrated continuation task but in different modes. For the multi-turn mode, participants reconstructed a picture story by continuing the episodes extracted from the story with one episode presented and continued at a time; for the single-turn mode, the first half of the same picture story was presented as a chunk, and then participants read and continued it. Results show that L2 learners aligned with the target structure in completing the story, and the alignment effect was retained in the posttest conducted after a delay of two weeks. Moreover, syntactic alignment was modulated by task mode with the multi-turn group exhibiting stronger immediate and longterm alignment effects. We conclude that the continuation task is a fruitful context for L2 structural alignment, and the magnitude of alignment effect hinges on interactive intensity.

Efficiency of Prolonged Prone Positioning for Mechanically Ventilated Patients Infected with COVID-19

Hypoxemia of the acute respiratory distress syndrome can be reduced by turning patients prone. Prone positioning (PP) is labor intensive, risks unplanned tracheal extubation, and can result in facial tissue injury. We retrospectively examined prolonged, repeated, and early versus later PP for 20 patients with COVID-19 respiratory failure. Blood gases and ventilator settings were collected before PP, at 1, 7, 12, 24, 32, and 39 h after PP, and 7 h after completion of PP. Analysis of variance was used for comparisons with baseline values at supine positions before turning prone. PP for >39 h maintained PaO2/FiO2 (P/F) ratios when turned supine; the P/F decrease at 7 h was not significant from the initial values when turned supine. Patients turned prone a second time, when again turned supine at 7 h, had significant decreased P/F. When PP started for an initial P/F ≤ 150 versus P/F > 150, the P/F increased throughout the PP and upon return to supine. Our results show that a single turn prone for >39 h is efficacious and saves the burden of multiple prone turns, and there is no significant advantage to initiating PP when P/F > 150 compared to P/F ≤ 150.