Integrated Sensing and Secure Communication with XL-MIMO.

This paper studies extremely large-scale multiple-input multiple-output (XL-MIMO)-empowered integrated sensing and secure communication systems, where both the radar targets and the communication user are located within the near-field region of the transmitter. The radar targets, being untrusted entities, have the potential to intercept the confidential messages intended for the communication user. In this context, we investigate the near-field beam-focusing design, aiming to maximize the achievable secrecy rate for the communication user while satisfying the transmit beampattern gain requirements for the radar targets. We address the corresponding globally optimal non-convex optimization problem by employing a semidefinite relaxation-based two-stage procedure. Additionally, we provide a sub-optimal solution to reduce complexity. Numerical results demonstrate that beam focusing enables the attainment of a positive secrecy rate, even when the radar targets and communication user align along the same angle direction.

Attention-Linear Trajectory Prediction.

Recently, a large number of Transformer-based solutions have emerged for the trajectory prediction task, but there are shortcomings in the effectiveness of Transformers in trajectory prediction. Specifically, while position encoding preserves some of the ordering information, the self-attention mechanism at the core of the Transformer has its alignment invariance that leads to the loss of temporal information, which is crucial for trajectory prediction. For this reason, we design a simple and efficient strategy for temporal information extraction and prediction of trajectory sequences using the self-attention mechanism and linear layers. The experimental results show that the strategy can improve the average accuracy by 15.31%, effectively combining the advantages of the linear layer and the self-attention mechanism, while compensating for the shortcomings of the Transformer. Additionally, we conducted an empirical study to explore the effectiveness of the linear layer and sparse self-attention mechanisms in trajectory prediction.

Multiattention Mechanism 3D Object Detection Algorithm Based on RGB and LiDAR Fusion for Intelligent Driving.

This paper proposes a multimodal fusion 3D target detection algorithm based on the attention mechanism to improve the performance of 3D target detection. The algorithm utilizes point cloud data and information from the camera. For image feature extraction, the ResNet50 + FPN architecture extracts features at four levels. Point cloud feature extraction employs the voxel method and FCN to extract point and voxel features. The fusion of image and point cloud features is achieved through regional point fusion and voxel fusion methods. After information fusion, the Coordinate and SimAM attention mechanisms extract fusion features at a deep level. The algorithm's performance is evaluated using the DAIR-V2X dataset. The results show that compared to the Part-A2 algorithm; the proposed algorithm improves the mAP value by 7.9% in the BEV view and 7.8% in the 3D view at IOU = 0.5 (cars) and IOU = 0.25 (pedestrians and cyclists). At IOU = 0.7 (cars) and IOU = 0.5 (pedestrians and cyclists), the mAP value of the SECOND algorithm is improved by 5.4% in the BEV view and 4.3% in the 3D view, compared to other comparison algorithms.

Elasticity of a Pseudoproper Ferroelastic Transition from Stishovite to Post-Stishovite at High Pressure.

Elastic moduli (C_{ij}) of single-crystal stishovite and post-stishovite are determined using Brillouin light scattering, impulsive stimulated light scattering, and x-ray diffraction up to 70 GPa. The C_{12} of stishovite converges with the C_{11} at ∼55 GPa, where the transverse wave V_{S1} propagating along [110] also vanishes. Landau modeling of the C_{ij}, B_{1g} optic mode, and lattice parameters reveals a pseudoproper type ferroelastic post-stishovite transition. The transition would cause peculiar anomalies in V_{S} and Poisson's ratio in silica-bearing subducting slabs in the mid-lower mantle.

Pressure-induced phase changes in natural fluorapophyllite-(K) studied by Raman spectroscopy.

The high-pressure Raman spectra in the low-wavenumber region (50-1200 cm-1) and the hydroxyl stretching vibration region (2600-3800 cm-1) of fluorapophyllite-(K) were collected in the interval of 0.0-50.7 GPa. Experimental results show that fluorapophyllite-(K) undergoes a crystalline-crystalline phase transition from a tetragonal structure (P4/mnc) to an orthorhombic structure (Pnnm) and then amorphization under high pressure conditions. Discontinuous changes in Raman peaks in the hydroxyl vibration region (2600-3800 cm-1) and the low-wavenumber region (50-1200 cm-1) occur at different onset pressures, suggesting that the destabilization of sub-lattices in fluorapophyllite-(K) under high pressure is not synchronous; the weak interlayer H2O structural units are more prone to destabilization at lower pressures than the rigid SiO4 tetrahedral layer units. Therefore, H2O groups in fluorapophyllite-(K) serve as sensitive local probes during the pressure-induced phase transition and amorphization.

Pressure-induced phase transitions in TmVO4 investigated by Raman spectroscopy.

The structural behavior of TmVO4 at pressures up to âˆ¼ 55 GPa was investigated by Raman spectroscopy. The changes in Raman spectra suggest the existence of three phase transitions upon compression. The first phase transition appeared at âˆ¼ 7.7 GPa, which was an irreversible phase transition from the ambient-pressure zircon phase to the scheelite phase, confirming previous X-ray measurements. Subsequently, the second reversible phase transition from the scheelite phase to the fergusonite phase occurred at âˆ¼ 23 GPa. Additional changes in the Raman spectra were observed at âˆ¼ 37 GPa, validating the third phase transition. Based on a comparison to related rare earth orthovanadates, we assumed that the post-fergusonite of TmVO4 has an orthorhombic structure described by space group Cmca. The wavenumbers of the Raman modes and their pressure coefficients for all four phases of TmVO4 are reported. Our study provides the vibrational difference in various polymorphs of TmVO4, which will refine our understanding of the structural behavior of rare-earth orthovanadates.

The application and progress of stem cells in auricular cartilage regeneration: a systematic review.

Background: The treatment of microtia or acquired ear deformities by surgery is a significant challenge for plastic and ENT surgeons; one of the most difficult points is constructing the scaffold for auricular reconstruction. As a type of cell with multiple differentiation potentials, stem cells play an essential role in the construction of cartilage scaffolds, and therefore have received widespread attention in ear reconstructive research. Methods: A literature search was conducted for peer-reviewed articles between 2005 and 2023 with the following keywords: stem cells; auricular cartilage; ear cartilage; conchal cartilage; auricular reconstruction, regeneration, and reparation of chondrocytes; tissue engineering in the following databases: PubMed, MEDLINE, Cochrane, and Ovid. Results: Thirty-three research articles were finally selected and their main characteristics were summarized. Adipose-derived stem cells (ADSCs), bone marrow mesenchymal stem cells (BMMSCs), perichondrial stem/progenitor cells (PPCs), and cartilage stem/progenitor cells (CSPCs) were mainly used in chondrocyte regeneration. Injecting the stem cells into the cartilage niche directly, co-culturing the stem cells with the auricular cartilage cells, and inducing the cells in the chondrogenic medium in vitro were the main methods that have been demonstrated in the studies. The chondrogenic ability of these cells was observed in vitro, and they also maintained good elasticity and morphology after implantation in vivo for a period of time. Conclusion: ADSC, BMMSC, PPC, and CSPC were the main stem cells that have been researched in craniofacial cartilage reconstruction, the regenerative cartilage performed highly similar to normal cartilage, and the test of AGA and type II collagen content also proved the cartilage property of the neo-cartilage. However, stem cell reconstruction of the auricle is still in the initial stage of animal experiments, transplantation with such scaffolds in large animals is still lacking, and there is still a long way to go.

The application and progress of tissue engineering and biomaterial scaffolds for total auricular reconstruction in microtia.

Microtia is a congenital deformity of the ear with an incidence of about 0.8-4.2 per 10,000 births. Total auricular reconstruction is the preferred treatment of microtia at present, and one of the core technologies is the preparation of cartilage scaffolds. Autologous costal cartilage is recognized as the best material source for constructing scaffold platforms. However, costal cartilage harvest can lead to donor-site injuries such as pneumothorax, postoperative pain, chest wall scar and deformity. Therefore, with the need of alternative to autologous cartilage, in vitro and in vivo studies of biomaterial scaffolds and cartilage tissue engineering have gradually become novel research hot points in auricular reconstruction research. Tissue-engineered cartilage possesses obvious advantages including non-rejection, minimally invasive or non-invasive, the potential of large-scale production to ensure sufficient donors and controllable morphology. Exploration and advancements of tissue-engineered cartilaginous framework are also emerging in aspects including three-dimensional biomaterial scaffolds, acquisition of seed cells and chondrocytes, 3D printing techniques, inducing factors for chondrogenesis and so on, which has greatly promoted the research process of biomaterial substitute. This review discussed the development, current application and research progress of cartilage tissue engineering in auricular reconstruction, particularly the usage and creation of biomaterial scaffolds. The development and selection of various types of seed cells and inducing factors to stimulate chondrogenic differentiation in auricular cartilage were also highlighted. There are still confronted challenges before the clinical application becomes widely available for patients, and its long-term effect remains to be evaluated. We hope to provide guidance for future research directions of biomaterials as an alternative to autologous cartilage in ear reconstruction, and finally benefit the transformation and clinical application of cartilage tissue engineering and biomaterials in microtia treatment.

Bioengineered MSC-derived exosomes in skin wound repair and regeneration.

Refractory skin defects such as pressure ulcers, diabetic ulcers, and vascular ulcers represent a challenge for clinicians and researchers in many aspects. The treatment strategies for wound healing have high cost and limited efficacy. To ease the financial and psychological burden on patients, a more effective therapeutic approach is needed to address the chronic wound. MSC-derived exosomes (MSC-exosomes), the main bioactive extracellular vesicles of the paracrine effect of MSCs, have been proposed as a new potential cell-free approach for wound healing and skin regeneration. The benefits of MSC-exosomes include their ability to promote angiogenesis and cell proliferation, increase collagen production, regulate inflammation, and finally improve tissue regenerative capacity. However, poor targeting and easy removability of MSC-exosomes from the wound are major obstacles to their use in clinical therapy. Thus, the concept of bioengineering technology has been introduced to modify exosomes, enabling higher concentrations and construction of particles of greater stability with specific therapeutic capability. The use of biomaterials to load MSC-exosomes may be a promising strategy to concentrate dose, create the desired therapeutic efficacy, and maintain a sustained release effect. The beneficial role of MSC-exosomes in wound healing is been widely accepted; however, the potential of bioengineering-modified MSC-exosomes remains unclear. In this review, we attempt to summarize the therapeutic applications of modified MSC-exosomes in wound healing and skin regeneration. The challenges and prospects of bioengineered MSC-exosomes are also discussed.

[Clinical application of link-pattern lateral popliteal artery perforator flap in repair of popliteal fossa scar].

OBJECTIVE: To discuss the feasibility and effectiveness of link-pattern lateral popliteal artery perforator flap in repairing popliteal fossa scar contracture in children or teenagers. METHODS: Between January 2009 and January 2013, 12 patients with popliteal fossa scar were admitted. Of them, 7 cases were male and 5 cases were female, aged from 3 to 17 years (median, 12 years). The disease duration was from 6 months to 5 years (median, 3 years). Wound was repaired with link-pattern lateral popliteal artery perforator flap after remission of popliteal fossa scar. The wound ranged from 6 cm x 4 cm to 10 cm x 7 cm, and the flap size ranged from 7 cm x 4 cm to 12 cm x 9 cm. The flap was with lateral sural cutaneous nerve in 5 cases, and lateral sural cutaneous nerve was retained at the donor area of 7 cases. The donor site was repaired using split- thickness skin graft. RESULTS: All pedicled flaps and skin graft survived smoothly after operation. The wound at donor site healed by first intention. All the cases were followed up 12-36 months, with an average of 18 months. The flaps had good color, texture, and shape; scar obviously became softened, without hyperplasia or ulceration. The patients were free from lameness with knee range of motion of 0-180°. The squatting function was normal. Grafting skin was smooth in the donor area of the calf, without depression or scar hyperplasia. The senses of posterior-inferior calf and lateral of foot decreased or disappeared in 5 cases of flaps with lateral sural cutaneous nerve; at 6 months after operation, two-point discrimination was 12-14 mm (mean, 13 mm). The posterior-inferior calf was numb and discomfort in 7 cases of flaps with retained lateral sural cutaneous nerve; but after 3-6 months, the sense was obviously recovered, with no sense loss; at 6 months after operation, two-point discrimination was 5-7 mm (mean, 6 min). CONCLUSION: Link-pattern lateral popliteal artery perforator flap has reliable blood supply and the operation was simple. The cutaneous nerve can be retained in donor area. It is an ideal method for repairing wound after remission of popliteal fossa scar in children or teenagers.