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The functionality of atomic quantum emitters is intrinsically linked to their host lattice coordination. Structural distortions that spontaneously break the lattice symmetry strongly impact their optical emission properties and spin-photon interface. Here we report on the direct imaging of charge state-dependent symmetry breaking of two prototypical atomic quantum emitters in mono- and bilayer MoS₂by scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM). By changing the built-in substrate chemical potential, different charge states of sulfur vacancies (Vac_S) and substitutional rhenium dopants (Re_Mo) can be stabilized. Vac$${}_{{{{{{{{\rm{S}}}}}}}}}^{-1}$$${}_S^{-1}$as well as Re$${}_{{{{{{{{\rm{Mo}}}}}}}}}^{0}$$${}_{\mathrm{Mo}}^0$and Re$${}_{{{{{{{{\rm{Mo}}}}}}}}}^{-1}$$${}_{\mathrm{Mo}}^{-1}$exhibit local lattice distortions and symmetry-broken defect orbitals attributed to a Jahn-Teller effect (JTE) and pseudo-JTE, respectively. By mapping the electronic and geometric structure of single point defects, we disentangle the effects of spatial averaging, charge multistability, configurational dynamics, and external perturbations that often mask the presence of local symmetry breaking.

 

We present a new analysis of the rest-frame ultraviolet (UV) and optical spectra of a sample of three z > 8 galaxies discovered behind the gravitational lensing cluster RX J2129.4+0009. We combine these observations with z > 7.5 galaxies from the literature, for which similar measurements are available. As already pointed out in other studies, the high [O iii]λ5007/[O ii]λ3727 ratios (O32) and steep UV continuum slopes (β) are consistent with the values observed for low-redshift Lyman continuum emitters, suggesting that such galaxies contribute to the ionizing budget of the intergalactic medium. We construct a logistic regression model to estimate the probability of a galaxy being a Lyman continuum emitter based on the measured MUV, β, and O32. Using this probability and the UV luminosity function, we construct an empirical model that estimates the contribution of high-redshift galaxies to reionization. The preferred scenario in our analysis shows that at z ∼ 8, the average escape fraction of the galaxy population [i.e. including both LyC emitters (LCEs) and non-emitters] varies with MUV, with intermediate UV luminosity (−19 < MUV < −16) galaxies having larger escape fraction. Galaxies with faint UV luminosity (−16 < MUV < −13.5) contribute most of the ionizing photons. The relative contribution of faint versus bright galaxies depends on redshift, with the intermediate UV galaxies becoming more important over time. UV bright galaxies, although more likely to be LCEs at a given log(O32) and β, contribute the least of the total ionizing photon budget.

 

Genes that regulate hormone release are essential for maintaining metabolism and energy balance. Egr1 encodes a transcription factor that regulates hormone production and release, and a decreased in growth hormones has been reported in Egr1 knockout mice. A reduction in growth hormones has also been observed in Nestin-Cre mice, a model frequently used to study the nervous system. Currently, it is unknown how Egr1 loss or the Nestin-Cre driver disrupt pituitary gene expression. Here, we compared the growth curves and pituitary gene expression profiles of Nestin-Cre-mediated Egr1 conditional knockout (Egr1cKO) mice with those of their controls. Reduced body weight was observed in both the Nestin-Cre and Egr1cKO mice, and the loss of Egr1 had a slightly more severe impact on female mice than on male mice. RNA-seq data analyses revealed that the sex-related differences were amplified in the Nestin-Cre-mediated Egr1 conditional knockout mice. Additionally, in the male mice, the influence of Egr1cKO on pituitary gene expression may be overridden by the Nestin-Cre driver. Differentially expressed genes associated with the Nestin-Cre driver were significantly enriched for genes related to growth factor activity and binding. Altogether, our results demonstrate that Nestin-Cre and the loss of Egr1 in the neuronal cell lineage have distinct impacts on pituitary gene expression in a sex-specific manner.

 

Post-transcriptional RNA modifications have been recognized as key regulators of neuronal differentiation and synapse development in the mammalian brain. While distinct sets of 5-methylcytosine (m5C) modified mRNAs have been detected in neuronal cells and brain tissues, no study has been performed to characterize methylated mRNA profiles in the developing brain. Here, together with regular RNA-seq, we performed transcriptome-wide bisulfite sequencing to compare RNA cytosine methylation patterns in neural stem cells (NSCs), cortical neuronal cultures, and brain tissues at three postnatal stages. Among 501 m5C sites identified, approximately 6% are consistently methylated across all five conditions. Compared to m5C sites identified in NSCs, 96% of them were hypermethylated in neurons and enriched for genes involved in positive transcriptional regulation and axon extension. In addition, brains at the early postnatal stage demonstrated substantial changes in both RNA cytosine methylation and gene expression of RNA cytosine methylation readers, writers, and erasers. Furthermore, differentially methylated transcripts were significantly enriched for genes regulating synaptic plasticity. Altogether, this study provides a brain epitranscriptomic dataset as a new resource and lays the foundation for further investigations into the role of RNA cytosine methylation during brain development. 

Massive MIMO systems can achieve high spectrum and energy efficiency in downlink (DL) based on accurate estimate of channel state information (CSI). Existing works have developed learning-based DL CSI estimation that lowers uplink feedback overhead. One often overlooked problem is the limited number of DL pilots available for CSI estimation. One proposed solution leverages temporal CSI coherence by utilizing past CSI estimates and only sending CSI-reference symbols (CSIRS) for partial arrays to preserve CSI recovery performance. Exploiting CSI correlations, FDD channel reciprocity is helpful to base stations with direct access to uplink CSI. In this work, we propose a new learning-based feedback architecture and a reconfigurable CSI-RS placement scheme to reduce DL CSI training overhead and to improve encoding efficiency of CSI feedback. Our results demonstrate superior performance in both indoor and outdoor scenarios by the proposed framework for CSI recovery at substantial reduction of computation power and storage requirements at UEs. 

Key Points Enhancement of field‐aligned warm ions observed in the plasma sheet was energy‐dispersive with increasing energy from 20 eV to >100 eV The probe at larger r observed the energy‐dispersive enhancements 20 min earlier than did the probe at smaller r The enhancements were likely caused by enhanced convection and the dispersion was likely due to acceleration by field‐aligned potential 

A tight positive correlation between the stellar mass and the gas-phase metallicity of galaxies has been observed at low redshifts. The redshift evolution of this correlation can strongly constrain theories of galaxy evolution. The advent of JWST allows probing the mass–metallicity relation at redshifts far beyond what was previously accessible. Here we report the discovery of two emission line galaxies at redshifts 8.15 and 8.16 in JWST NIRCam imaging and NIRSpec spectroscopy of targets gravitationally lensed by the cluster RX J2129.4+0005. We measure their metallicities and stellar masses along with nine additional galaxies at 7.2 <z_spec< 9.5 to report the first quantitative statistical inference of the mass–metallicity relation atz≈ 8. We measure ∼0.9 dex evolution in the normalization of the mass–metallicity relation fromz≈ 8 to the local universe; at a fixed stellar mass, galaxies are 8 times less metal enriched atz≈ 8 compared to the present day. Our inferred normalization is in agreement with the predictions of FIRE simulations. Our inferred slope of the mass–metallicity relation is similar to or slightly shallower than that predicted by FIRE or observed at lower redshifts. We compare thez≈ 8 galaxies to extremely low-metallicity analog candidates in the local universe, finding that they are generally distinct from extreme emission line galaxies or “green peas,” but are similar in strong emission line ratios and metallicities to “blueberry galaxies.” Despite this similarity, at a fixed stellar mass, thez≈ 8 galaxies have systematically lower metallicities compared to blueberry galaxies.