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The molecular architecture of engulfment during Bacillus subtilis sporulation.
The study of bacterial cell biology is limited by difficulties in visualizing cellular structures at high spatial resolution within their native milieu. Here, we visualize Bacillus subtilis sporulation using cryo-electron tomography coupled with cryo-focused ion beam milling, allowing the reconstruction of native-state cellular sections at molecular resolution. During sporulation, an asymmetrically-positioned septum generates a larger mother cell and a smaller forespore. Subsequently, the mother cell engulfs the forespore. We show that the septal peptidoglycan is not completely degraded at the onset of engulfment. Instead, the septum is uniformly and only slightly thinned as it curves towards the mother cell. Then, the mother cell membrane migrates around the forespore in tiny finger-like projections, whose formation requires the mother cell SpoIIDMP protein complex. We propose that a limited number of SpoIIDMP complexes tether to and degrade the peptidoglycan ahead of the engulfing membrane, generating an irregular membrane front
Channel Measurements and Modeling for Dynamic Vehicular ISAC Scenarios at 28 GHz
Integrated sensing and communication (ISAC) is a promising technology for 6G,
with the goal of providing end-to-end information processing and inherent
perception capabilities for future communication systems. Within ISAC emerging
application scenarios, vehicular ISAC technologies have the potential to
enhance traffic efficiency and safety through integration of communication and
synchronized perception abilities. To establish a foundational theoretical
support for vehicular ISAC system design and standardization, it is necessary
to conduct channel measurements, and modeling to obtain a deep understanding of
the radio propagation. In this paper, a dynamic statistical channel model is
proposed for vehicular ISAC scenarios, incorporating Sensing Multipath
Components (S-MPCs) and Clutter Multipath Components (C-MPCs), which are
identified by the proposed tracking algorithm. Based on actual vehicular ISAC
channel measurements at 28 GHz, time-varying sensing characteristics in front,
left, and right directions are investigated. To model the dynamic evolution
process of channel, number of new S-MPCs, lifetimes, initial power and delay
positions, dynamic variations within their lifetimes, clustering, power decay,
and fading of C-MPCs are statistically characterized. Finally, the paper
provides implementation of dynamic vehicular ISAC model and validates it by
comparing key simulation statistics between measurements and simulations
Characterization of Wireless Channel Semantics: A New Paradigm
Recently, deep learning enabled semantic communications have been developed
to understand transmission content from semantic level, which realize effective
and accurate information transfer. Aiming to the vision of sixth generation
(6G) networks, wireless devices are expected to have native perception and
intelligent capabilities, which associate wireless channel with surrounding
environments from physical propagation dimension to semantic information
dimension. Inspired by these, we aim to provide a new paradigm on wireless
channel from semantic level. A channel semantic model and its characterization
framework are proposed in this paper. Specifically, a channel semantic model
composes of status semantics, behavior semantics and event semantics. Based on
actual channel measurement at 28 GHz, as well as multi-mode data, example
results of channel semantic characterization are provided and analyzed, which
exhibits reasonable and interpretable semantic information
Transformer-Based Multi-Aspect Multi-Granularity Non-Native English Speaker Pronunciation Assessment
Automatic pronunciation assessment is an important technology to help
self-directed language learners. While pronunciation quality has multiple
aspects including accuracy, fluency, completeness, and prosody, previous
efforts typically only model one aspect (e.g., accuracy) at one granularity
(e.g., at the phoneme-level). In this work, we explore modeling multi-aspect
pronunciation assessment at multiple granularities. Specifically, we train a
Goodness Of Pronunciation feature-based Transformer (GOPT) with multi-task
learning. Experiments show that GOPT achieves the best results on
speechocean762 with a public automatic speech recognition (ASR) acoustic model
trained on Librispeech.Comment: Accepted at ICASSP 2022. Code at https://github.com/YuanGongND/gopt
Interactive Colab demo at
https://colab.research.google.com/github/YuanGongND/gopt/blob/master/colab/GOPT_GPU.ipynb
. ICASSP 202
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