Double RIS-Assisted MIMO Systems Over Spatially Correlated Rician Fading Channels and Finite Scatterers

This paper investigates double RIS-assisted MIMO communication systems over Rician fading channels with finite scatterers, spatial correlation, and the existence of a double-scattering link between the transceiver. First, the statistical information is driven in closed form for the aggregated channels, unveiling various influences of the system and environment on the average channel power gains. Next, we study two active and passive beamforming designs corresponding to two objectives. The first problem maximizes channel capacity by jointly optimizing the active precoding and combining matrices at the transceivers and passive beamforming at the double RISs subject to the transmitting power constraint. In order to tackle the inherently non-convex issue, we propose an efficient alternating optimization algorithm (AO) based on the alternating direction method of multipliers (ADMM). The second problem enhances communication reliability by jointly training the encoder and decoder at the transceivers and the phase shifters at the RISs. Each neural network representing a system entity in an end-to-end learning framework is proposed to minimize the symbol error rate of the detected symbols by controlling the transceiver and the RISs phase shifts. Numerical results verify our analysis and demonstrate the superior improvements of phase shift designs to boost system performance.Comment: 15 pages, 9 figures, accepted by IEEE Transactions on Communication

Uplink Sum Throughput Analysis and Maximization for Integrated Satellite-Terrestrial Cell-Free Massive MIMO

peer reviewedThis paper studies multiple-access scenarios where users are cooperatively served by the satellite and terrestrial access points (APs). We derive the uplink ergodic throughput of scheduled users under practical conditions where maximumradio combining is exploited locally at the ground gateway and the APs. The analytical result explicitly unveils the effects of pilot contamination and channel conditions on the achievable throughput of each scheduled user in the uplink data transmission. The system can explicitly define the scheduled users and perform the power allocation by maximizing the sum throughput using either model-based or learning-based approaches. Numerical results demonstrate that the cooperation between space and ground systems brings superior throughput improvements over either space or ground networks. Even though most users can be simultaneously served, some may not be scheduled in each coherence interval due to limited radio resources

Nanocomposite Thin Film TiO2/CdS Electrodes Prepared by Thermal Evaporation Process for Photovoltaic Applications

The incorporation of cadmium sulfide (CdS) into TiO2 nanoparticle thin films was investigated. The nanoparticle TiO2 thin film onto an indium doped–tin oxide (ITO) substrate was deposited by Electron Beam Deposition (EBD) combined with thermal process. Then a CdS thin film was vacuum-deposited onto the pre-deposited TiO2 film by a thermal evaporation technique. The obtained TiO2/CdS was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). The TiO2/CdS nanocomposite film was used in a photo-electrochemical (PEC) cell as a working electrode and a platinum electrode as a counter electrode. The electrolyte solution contains 1 M KCl and 0.1M Na2S. The results show that the cell with TiO2/CdS composite film electrode has significantly improved photoelectric capability in comparison with that of the pure TiO2 thin films

Comparative analysis of root transcriptomes from two contrasting drought-responsive Williams 82 and DT2008 soybean cultivars under normal and dehydration conditions

The economically important DT2008 and the model Williams 82 (W82) soybean cultivars were reported to have differential drought-tolerant degree to dehydration and drought, which was associated with root trait. Here, we used 66K Affymetrix Soybean Array GeneChip to compare the root transcriptomes of DT2008 and W82 seedlings under normal, as well as mild (2h treatment) and severe (10h treatment) dehydration conditions. Out of the 38172 soybean genes annotated with high confidence, 822 (2.15%) and 632 (1.66%) genes showed altered expression by dehydration in W82 and DT2008 roots, respectively, suggesting that a larger machinery is required to be activated in the drought-sensitive W82 cultivar to cope with the stress. We also observed that long-term dehydration period induced expression change of more genes in soybean roots than the short-term one, independently of the genotypes. Furthermore, our data suggest that the higher drought tolerability of DT2008 might be attributed to the higher number of genes induced in DT2008 roots than in W82 roots by early dehydration, and to the expression changes of more genes triggered by short-term dehydration than those by prolonged dehydration in DT2008 roots vs. W82 roots. Differentially expressed genes (DEGs) that could be predicted to have a known function were further analyzed to gain a basic understanding on how soybean plants respond to dehydration for their survival. The higher drought tolerability of DT2008 vs. W82 might be attributed to differential expression in genes encoding osmoprotectant biosynthesis-, detoxification- or cell wall-related proteins, kinases, transcription factors and phosphatase 2C proteins. This research allowed us to identify genetic components that contribute to the improved drought tolerance of DT2008, as well as provide a useful genetic resource for in-depth functional analyses that ultimately leads to development of soybean cultivars with improved tolerance to drought

A New Technique of Two Iliac Cortical Bone Blocks Sandwich Technique for Secondary Alveolar Bone Grafting in Cleft Lip and Palate Patients

Alveolar cleft bone graft in the second stage of surgery was a crucial part of the cleft palate treatment protocol with many advantages: reconstructing bone for tooth eruption, supporting the periodontal structure for the teeth adjacent to the cleft, supporting and lifting the arch and preventing from collapsing of maxillary arch. Grafting technique and material are selected based on the treatment purpose that for orthodontic moving tooth into the arch or for dental implant rehabilitation. Cancellous material provides rapid vascularization and healing facilitating for tooth moving into the cleft site but easy to resorb that unsuitable for dental implant placement. While dense material is difficult to move teeth into the cleft but increase initial stability. Therefore, we offered a method that limit bone resorption, easily obtain the implant initial stability, quick osseointegration called two iliac cortical bone blocks sandwich technique for a purposes of dental implant rehabilitation. Treatment protocol started with orthodontic treatment prior alveolar bone grafting to create proper space for implant restoration. Our clinical experience with 32 cleft sites using two iliac cortical bone blocks sandwich had shown potential clinical application in follow-up time up to 96 months. Evaluation criteria of bone grafting for alveolar cleft included soft tissue condition of graft area, nasal fistula closure, bone grafting outcome, success in osseointegration and implant prosthesis. This chapter described in detail treatment procedure and outcomes of a new technique of two iliac cortical bone blocks sandwich for alveolar cleft in patients with unilateral cleft palate

The results of deep magnetotelluric sounding for studying the Nha Trang - Tanh Linh fault

The profile of deep magnetotelluric sounding (MT) from Duc Trong - Tuy Phong has been carried out in Lam Dong and Binh Thuan  provinces. The length of the Duc Trong - Tuy Phong profile is about 80 km with 15 stations and the distance between the stations measures about 5 km. Two-dimensional MT inversion was used to find a resistivity model that fits the data. The 2D resistivity model allows determining position and development formation of the Nha Trang - Tanh Linh  fault. This is the deep fault, which is showed by the boundaries of remarkable change of resistivity. In the near surface of the Earth (from ground to the depth of 6 km), the angle of inclination of this fault is about 60o; in the next part, the direction of the Nha Trang - Tanh Linh  faut is vertical. Geoelectrical section of the Nha Trang - Tanh Linh  profile shows that the resistivity of mid-crust is higher than that of lower-crust and of upper-crust

Function of KAI2 signaling in plant drought adaptation

Drought causes substantial reductions in crop yields worldwide. Therefore, we set out to identify new chemical and genetic factors that regulate drought resistance in Arabidopsis thaliana. Karrikins (KARs) are a class of butenolide compounds found in smoke that promote seed germination, and have been reported to improve seedling vigor under stressful growth conditions. Here, we discovered that mutations in KARRIKIN INSENSITIVE2 (KAI2), encoding the proposed karrikin receptor, result in hypersensitivity to water deprivation. We performed transcriptomic, physiological and biochemical analyses of kai2 plants to understand the basis for KAI2-regulated drought resistance. We found that kai2 mutants have increased rates of water loss and drought-induced cell membrane damage, enlarged stomatal apertures, and higher cuticular permeability. In addition, kai2 plants have reduced anthocyanin biosynthesis during drought, and are hyposensitive to abscisic acid (ABA) in stomatal closure and cotyledon opening assays. We identified genes that are likely associated with the observed physiological and biochemical changes through a genome-wide transcriptome analysis of kai2 under both well-watered and dehydration conditions. These data provide evidence for crosstalk between ABA- and KAI2-dependent signaling pathways in regulating plant responses to drought. A comparison of the strigolactone receptor mutant d14 (DWARF14) to kai2 indicated that strigolactones also contributes to plant drought adaptation, although not by affecting cuticle development. Our findings suggest that chemical or genetic manipulation of KAI2 and D14 signaling may provide novel ways to improve drought resistance