Semantic Entropy Can Simultaneously Benefit Transmission Efficiency and Channel Security of Wireless Semantic Communications

Recently proliferated deep learning-based semantic communications (DLSC) focus on how transmitted symbols efficiently convey a desired meaning to the destination. However, the sensitivity of neural models and the openness of wireless channels cause the DLSC system to be extremely fragile to various malicious attacks. This inspires us to ask a question: "Can we further exploit the advantages of transmission efficiency in wireless semantic communications while also alleviating its security disadvantages?". Keeping this in mind, we propose SemEntropy, a novel method that answers the above question by exploring the semantics of data for both adaptive transmission and physical layer encryption. Specifically, we first introduce semantic entropy, which indicates the expectation of various semantic scores regarding the transmission goal of the DLSC. Equipped with such semantic entropy, we can dynamically assign informative semantics to Orthogonal Frequency Division Multiplexing (OFDM) subcarriers with better channel conditions in a fine-grained manner. We also use the entropy to guide semantic key generation to safeguard communications over open wireless channels. By doing so, both transmission efficiency and channel security can be simultaneously improved. Extensive experiments over various benchmarks show the effectiveness of the proposed SemEntropy. We discuss the reason why our proposed method benefits secure transmission of DLSC, and also give some interesting findings, e.g., SemEntropy can keep the semantic accuracy remain 95% with 60% less transmission.Comment: 13 pages, 12 figure

An Evolutionarily Conserved Enhancer Regulates Bmp4 Expression in Developing Incisor and Limb Bud

To elucidate the transcriptional regulation of Bmp4 expression during organogenesis, we used phylogenetic footprinting and transgenic reporter analyses to identify Bmp4 cis-regulatory modules (CRMs). These analyses identified a regulatory region located ∼46 kb upstream of the mouse Bmp4 transcription start site that had previously been shown to direct expression in lateral plate mesoderm. We refined this regulatory region to a 396-bp minimal enhancer, and show that it recapitulates features of endogenous Bmp4 expression in developing mandibular arch ectoderm and incisor epithelium during the initiation-stage of tooth development. In addition, this enhancer directs expression in the apical ectodermal ridge (AER) of the developing limb and in anterior and posterior limb mesenchyme. Transcript profiling of E11.5 mouse incisor dental lamina, together with protein binding microarray (PBM) analyses, allowed identification of a conserved DNA binding motif in the Bmp4 enhancer for Pitx homeoproteins, which are also expressed in the developing mandibular and incisor epithelium. In vitro electrophoretic mobility shift assays (EMSA) and in vivo transgenic reporter mutational analyses revealed that this site supports Pitx binding and that the site is necessary to recapitulate aspects of endogenous Bmp4 expression in developing craniofacial and limb tissues. Finally, Pitx2 chromatin immunoprecipitation (ChIP) demonstrated direct binding of Pitx2 to this Bmp4 enhancer site in a dental epithelial cell line. These results establish a direct molecular regulatory link between Pitx family members and Bmp4 gene expression in developing incisor epithelium

Pluronic F-127 hydrogel as a promising scaffold for encapsulation of dental-derived mesenchymal stem cells

Dental-derived mesenchymal stem cells (MSCs) provide an advantageous therapeutic option for tissue engineering due to their high accessibility and bioavailability. However, delivering MSCs to defect sites while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated tissue regeneration. Here, we tested the osteogenic and adipogenic differentiation capacity of dental pulp stem cells (DPSCs) in a thermoreversible Pluronic F127 hydrogel scaffold encapsulation system in vitro. DPSCs were encapsulated in Pluronic(®) F-127 hydrogel and stem cell viability, proliferation and differentiation into adipogenic and osteogenic tissues were evaluated. The degradation profile and swelling kinetics of the hydrogel were also analyzed. Our results confirmed that Pluronic F-127 is a promising and non-toxic scaffold for encapsulation of DPSCs as well as control human bone marrow MSCs (hBMMSCs), yielding high stem cell viability and proliferation. Moreover, after 2 weeks of differentiation in vitro, DPSCs as well as hBMMSCs exhibited high levels of mRNA expression for osteogenic and adipogenic gene markers via PCR analysis. Our histochemical staining further confirmed the ability of Pluronic F-127 to direct the differentiation of these stem cells into osteogenic and adipogenic tissues. Furthermore, our results revealed that Pluronic F-127 has a dense tubular and reticular network morphology, which contributes to its high permeability and solubility, consistent with its high degradability in the tested conditions. Altogether, our findings demonstrate that Pluronic F-127 is a promising scaffold for encapsulation of DPSCs and can be considered for cell delivery purposes in tissue engineering