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Catalytic Asymmetric Carbosilylation of Methyl Propiolate with Bis-silyl Ketene Acetals
No full textWe report a catalytic asymmetric silylative α-alkenylation of bis-silyl ketene acetals (bis-SKAs) with methyl propiolate via conjugate addition. In contrast to prior Brønsted-base activation of C–H acidic nucleophiles (β-ketoesters and oxazolones), electrophilic activation of the alkynoate through silylium-asymmetric counteranion-directed catalysis (Si-ACDC) enables this transformation. DFT studies support a pathway in which silylium-mediated addition forms a substituted alkoxy(trimethylsilyloxy)propadiene (silyl propadienone acetal, SPA) that rapidly isomerizes via C-silylation accompanied by an O-desilylation to the α,β-unsaturated α-silyl ester with high stereocontrol. The reaction shows a broad scope with uniformly excellent enantio- and diastereoselectivities, and we demonstrate several downstream modifications of the products
Peeling layers reveal hidden quantum states in kagome materials
No full textFlat-band kagome materials exhibit a unique interplay between geometric frustration and strong electron correlations. Huang et al. demonstrate that exfoliating Nb3Cl8 flakes introduces strain, stabilizing a high-temperature phase with spin fluctuations that persist down to cryogenic temperatures. This finding has implications for future research into hidden quantum phases and the exotic properties of kagome materials
Scheme of Arrangement – Triangular Merger – Aktientausch: Variationen zum Konzerntransaktionsrecht
No full textInteractions between crabs and the environment: progress and prospects from a behavioral perspective
No full textThe link between GABA levels and P300 abnormalities in schizophrenia spectrum disorders: regional and symptom-based insights
No full textAccording to the excitation-inhibition imbalance theory, GABAergic and glutamatergic systems influence the clinical symptoms, particularly cognitive deficits in schizophrenia spectrum disorders (SSD). These systems have been found disrupted in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) in SSD, and may contribute to P300 abnormalities in electroencephalography recordings. Therefore, we explored the relationships among MRS-derived GABA and Glx levels in the ACC and left DLPFC (lDLPFC), auditory P3b subcomponent amplitudes and latencies, cognition, and symptom severity in SSD. In total, 107 patients and 107 healthy controls (HC) were included in the study, with the exact numbers varying across specific analyses. We grouped patients into higher (SSD+, N = 41) and lower (SSD−, N = 65) symptom severity clusters based on PANSS total scores. P3b amplitudes were lower in SSD patients than HC at central and parietal sites. SSD+ exhibited widespread P3b amplitude reductions, significant at parietal and trend-level at central and frontal regions, while SSD− showed a trend-level amplitude reduction limited to the parietal region. GABA levels in the lDLPFC were higher in SSD− compared to controls and were positively associated with P3b amplitudes at central and parietal sites within SSD− and overall SSD group. Although P3b amplitudes positively correlated with the BACS composite scores and behavioral performance, lDLPFC GABA levels showed no direct association with cognitive or behavioral performance. ACC GABA, ACC Glx, and lDLPFC Glx levels showed no group differences or P3b associations. Our findings suggest P3b amplitude reductions as a marker of cognitive dysfunction in SSD, more pronounced in patients with higher illness severity, and that enhanced lDLPFC GABA may contribute to offsetting these reductions. Our work provides the first empirical evidence of the interplay between the GABAergic system and cortical electrophysiological signal patterns associated with cognitive dysfunction in SSD
Does predation risk constrain behavior in prey species? A test with five species of Neotropical forest mammals
No full textA smart challenge but ultimately mistimed and misleading: Commentary on Baumard and André
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Infinite hidden Markov models can dissect the complexities of learning
No full textLearning the contingencies of a task is difficult. Individuals learn in an idiosyncratic manner, revising their approach multiple times as they explore and adapt. Quantitative characterization of these learning curves requires a model that can capture both new behaviors and slow changes in existing ones. Here we suggest a dynamic infinite hidden semi-Markov model, whose latent states are associated with specific components of behavior. This model can describe new behaviors by introducing new states and capture more modest adaptations through dynamics in existing states. We tested the model by fitting it to behavioral data of >100 mice learning a contrast-detection task. Although animals showed large interindividual differences while learning this task, most mice progressed through three stages of task understanding, new behavior often arose at session onset, and early response biases did not predict later ones. We thus provide a new tool for comprehensively capturing behavior during learning
Versatile molecular tools enabling customizable DNA methylation editing in Arabidopsis
No full textTools to edit DNA methylation in a targeted manner are vital for establishing causal relationships between DNA methylation and its function, as well as for plant breeding and gene therapy. Here, by constructing dCas9 fusions to a panel of effectors and cofactors, we develop a range of highly effective tools for editing DNA methylation in Arabidopsis, including five tools for DNA methylation and six tools for DNA demethylation. Our tools show a diversity of performance features in terms of specificity and efficiency, offering either the capacity to edit DNA methylation in a target-specific manner or the ability to edit DNA methylation genome-wide due to potent off-target effect. Importantly, DNA methylation edited by these tools is inherited in the absence of transgene. These versatile tools pave the way for diverse applications of DNA methylation editing in not only research but also epigenetic breeding of crops