Multiobjective optimization guided by image quality index for limited-angle CT image reconstruction.

BACKGROUND: Due to the incomplete projection data collected by limited-angle computed tomography (CT), severe artifacts are present in the reconstructed image. Classical regularization methods such as total variation (TV) minimization, ℓ0 minimization, are unable to suppress artifacts at the edges perfectly. Most existing regularization methods are single-objective optimization approaches, stemming from scalarization methods for multiobjective optimization problems (MOP). OBJECTIVE: To further suppress the artifacts and effectively preserve the edge structures of the reconstructed image. METHOD: This study presents a multiobjective optimization model incorporates both data fidelity term and ℓ0-norm of the image gradient as objective functions. It employs an iterative approach different from traditional scalarization methods, using the maximization of structural similarity (SSIM) values to guide optimization rather than minimizing the objective function.The iterative method involves two steps, firstly, simultaneous algebraic reconstruction technique (SART) optimizes the data fidelity term using SSIM and the Simulated Annealing (SA) algorithm for guidance. The degradation solution is accepted in the form of probability, and guided image filtering (GIF) is introduced to further preserve the image edge when the degradation solution is rejected. Secondly, the result from the first step is integrated into the second objective function as a constraint, we use ℓ0 minimization to optimize ℓ0-norm of the image gradient, and the SSIM, SA algorithm and GIF are introduced to guide optimization process by improving SSIM value like the first step. RESULTS: With visual inspection, the peak signal-to-noise ratio (PSNR), root mean square error (RMSE), and SSIM values indicate that our approach outperforms other traditional methods. CONCLUSIONS: The experiments demonstrate the effectiveness of our method and its superiority over other classical methods in artifact suppression and edge detail restoration.

New Conceptual Catalyst on Spatial High-Entropy Alloy Heterostructures for High-Performance Li-O2 Batteries.

High-entropy alloys (HEAs) are attracting increased attention as an alternative to noble metals for various catalytic reactions. However, it is of great challenge and fundamental importance to develop spatial HEA heterostructures to manipulate d-band center of interfacial metal atoms and modulate electron-distribution to enhance electrocatalytic activity of HEA catalysts. Herein, an efficient strategy is demonstrated to construct unique well-designed HEAs spatial heterostructure electrocatalyst (HEA@Pt) as bifunctional cathode to accelerate oxygen reduction and evolution reaction (ORR/OER) kinetics for Li-O2 batteries, where uniform Pt dendrites grow on PtRuFeCoNi HEA at a low angle boundary. Such atomically connected HEA spatial interfaces engender efficient electrons from HEA to Pt due to discrepancy of work functions, modulating electron distribution for fast interfacial electron transfer, and abundant active sites. Theoretical calculations reveal that electron redistribution manipulates d-band center of interfacial metal atoms, allowing appropriate adsorption energy of oxygen species to lower ORR/OER reaction barriers. Hence, Li-O2 battery based on HEA@Pt electrocatalyst delivers a minimal polarization potential (0.37 V) and long-term cyclability (210 cycles) under a cut-off capacity of 1000 mAh g-1 , surpassing most previously reported noble metal-based catalysts. This work provides significant insights on electron-modulation and d-band center optimization for advanced electrocatalysts.

RICT: Rotating image computed tomography with a one-to-one reversible image rotation algorithm.

BACKGROUND: The Mueller, Siddon and Joseph weighting algorithms are frequently used for projection and back-projection, which are relatively complicated when they are implemented in computer code. OBJECTIVE: This study aims to reduce the actual complexity of the projection and back-projection. METHODS: First, we neglect the exact shape of the pixel, so that its shadow is a rectangle projecting precisely to a detector bin, which implies that all the pixel weights are exactly 1 for each ray through them, otherwise are exactly 0. Next, a one-to-one reversible image rotation algorithm (RIRA) is proposed to compute the projection and back-projection, where two one-to-one mapping lists namely, U and V, are used to store the coordinates of a rotated pixel and its corresponding new coordinates, respectively. For each 2D projection, the projection is simply the column sum in each orientation according to the lists U and V. For each 2D back-projection, it is simply to arrange the projection to the corresponding column element according to the lists U and V. Thus, there is no need for an interpolation in the projection and back-projection. Last, a rotating image computed tomography (RICT) based on RIRA is proposed to reconstruct the image. RESULTS: Experiments show the RICT reconstructs a good image that is close to the result of filtered back-projection (FBP) method according to the RMSE, PSNR and MSSIM values. What's more, our weight, projection and back-projection are much easier to be implemented in computer code than the FBP method. CONCLUSION: This study demonstrates that the RIRA method has potential to be used to simplify many computed tomography image reconstruction algorithms.

Pan-KRAS inhibitors suppress proliferation through feedback regulation in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is currently one of the most lethal cancers worldwide. Several basic studies have confirmed that Kirsten rat sarcoma virus (KRAS) is a key driver gene for the occurrence of PDAC, and KRAS mutations have also been found in most patients in clinical studies. In this study, two pan-KRAS inhibitors, BI-2852 and BAY-293, were chosen as chemical probes to investigate their antitumor potency in PDAC. Their inhibitory effects on KRAS activation were validated in vitro and their antiproliferative potency in PDAC cell lines were profiled, with half-maximal inhibitory concentration (IC50) values of approximately 1 µM, demonstrating the therapeutic potential of pan-KRAS inhibitors in the treatment of PDAC. However, feedback regulation in the KRAS pathway weakened inhibitor activity, which was observed by a 50 times difference in BAY-293 from in vitro activity. Furthermore, pan-KRAS inhibitors effectively inhibited cell proliferation in 3D organoids cultured from PDAC patient samples; however, there were some variations between individuals. These results provide a sufficient theoretical foundation for KRAS as a clinical therapeutic target and for the application of pan-KRAS inhibitors in the treatment of PDAC, with important scientific significance in translational medicine.

Cancer associates with risk and severe events of COVID-19: A systematic review and meta-analysis.

Evidence is mounting to indicate that cancer patients may have more likelihood of having coronavirus disease 2019 (COVID-19) but lack consistency. A robust estimate is urgently needed to convey appropriate information to the society and the public, in the time of ongoing COVID-19 pandemic. We performed a systematic review and meta-analysis through a comprehensive literature search in major databases in English and Chinese, and two investigators conducted publication selection and data extraction independently. A meta-analysis was used to obtain estimates of pooled prevalence of cancer in patients with COVID-19 and determine the association of cancer with severe events, after assessment of potential heterogeneity, publication bias, and correction for the estimates when necessary. Total 38 studies comprising 7094 patients with COVID-9 were included; the pooled prevalence of cancer was estimated at 2.3% (95% confidence limit [CL] [0.018, 0.029]; P < .001) overall and 3.2% (95% CL [0.023, 0.041]; P < .001) in Hubei province; the corresponding estimates were 1.4% and 1.9% after correction for publication bias; cancer was significantly associated with the events of severe cases (odds ratio [OR] = 2.20, 95% CL [1.53, 3.17]; P < .001) and death (OR = 2.97, 95% CL [1.48, 5.96]; P = .002) in patients with COVID-19, there was no significant heterogeneity and a minimal publication bias. We conclude that cancer comorbidity is associated with the risk and severe events of COVID-19; special measures should be taken for individuals with cancer.

Analysis of terpenoid biosynthesis pathways in German chamomile (Matricaria recutita) and Roman chamomile (Chamaemelum nobile) based on co-expression networks.

German chamomile and Roman chamomile are the two most widely known chamomile species due to the medicinal properties of volatile compounds from their flowers. We determined the volatile compound content of different organs of these two chamomiles, and found that main volatile compounds in German chamomile were terpenoids and those in Roman chamomile were esters. Furthermore, 24 tissues from two chamomiles were sequenced and analyzed by gene co-expression network. The results showed higher terpene synthase expression levels and more modules correlated with sesquiterpenoids in German chamomile, which may explain its high sesquiterpenoid content. In both chamomiles, unigenes in volatile compound-correlated modules were significantly enriched in pathways related to plant-pathogen interactions and circadian rhythm, demonstrating that volatile compounds of chamomiles are influenced by these factors. There were ten times more unigenes related to plant-pathogen interactions in German chamomile than in Roman chamomile, which indicates German chamomile has higher resistance to pathogens.

[Network pharmacological analysis and experimental study of Pulsatilla chinensis against inflammatory injury caused by pneumonia in mice infected with influenza virus FM_1].

Network pharmacology and the mouse model of viral pneumonia caused by influenza virus FM_1 were employed to explore the main active components and the mechanism of Pulsatilla chinensis against the inflammatory injury of influenza virus-induced pneumonia. The components and targets of P. chinensis were searched from TCMSP, and the targets associated with influenza virus-induced pneumonia were searched from GeneCards. The common targets between P. chinensis and influenza virus-induced pneumonia were identified with Venn diagram established in Venny 2.1. The herb-component-disease-target(H-C-D-T) network was constructed by Cytoscape 3.7.2. The above data were imported into STRING for PPI network analysis. Gene Ontology(GO) enrichment and KEGG pathway enrichment were performed with DAVID. BALB/cAnN mice were infected with the influenza virus FM_1 by nasal drip to gene-rate the mouse model of pneumonia. Immunohistochemistry was adopted to the expression profiling of inflammatory cytokines in the lung tissues of mice in the blank group, model group, and P. chinensis group 1, 3, 5, and 7 days after infection. The pathological changes of lung and trachea of mice in blank group, model group, and P. chinensis group were observed with light microscope and scanning electron microscope at all the time points. The network pharmacological analysis indicated that 9 compounds of P. chinensis were screened out, with a total of 57 targets, 22 of which were overlapped with those of influenza virus-induced pneumonia. A total of 112 GO terms(P<0.05) were enriched, including 81 terms of biological processes, 11 terms of cell components, and 20 terms of molecular functions. A total of 53 KEGG signaling pathways(P<0.05) were enriched, including TNF signaling pathway, influenza A signaling pathway, NF-κB signaling pathway, MAPK signaling pathway and other signaling pathways related to influenza/inflammation. In the P. chinensis group, the expression of TNF-α and IL-1 in the lung tissue was down-regulated on the 3 rd day after infection, and that of IL-6 in the lung tissue was down-regulated on the 5 th day after infection. Light microscopy and scanning electron microscopy showed that P. chinensis significantly alleviated the pathological damage of lung and trachea compared with the model group. This study reflects the multi-components, multi-targets, and multi-pathways of P. chinensis against influenza virus-induced pneumonia. P. chinensis may reduce the production of proinflammatory cytokines and mediators and block the pro-inflammatory signaling pathways to alleviate viral pneumonia, which provides reference for future research.

Phytochemical and comparative transcriptome analyses reveal different regulatory mechanisms in the terpenoid biosynthesis pathways between Matricaria recutita L. and Chamaemelum nobile L.

BACKGROUND: Matricaria recutita (German chamomile) and Chamaemelum nobile (Roman chamomile) belong to the botanical family Asteraceae. These two herbs are not only morphologically distinguishable, but their secondary metabolites - especially the essential oils present in flowers are also different, especially the terpenoids. The aim of this project was to preliminarily identify regulatory mechanisms in the terpenoid biosynthetic pathways that differ between German and Roman chamomile by performing comparative transcriptomic and metabolomic analyses. RESULTS: We determined the content of essential oils in disk florets and ray florets in these two chamomile species, and found that the terpenoid content in flowers of German chamomile is greater than that of Roman chamomile. In addition, a comparative RNA-seq analysis of German and Roman chamomile showed that 54% of genes shared > 75% sequence identity between the two species. In particular, more highly expressed DEGs (differentially expressed genes) and TF (transcription factor) genes, different regulation of CYPs (cytochrome P450 enzymes), and rapid evolution of downstream genes in the terpenoid biosynthetic pathway of German chamomile could be the main reasons to explain the differences in the types and levels of terpenoid compounds in these two species. In addition, a phylogenetic tree constructed from single copy genes showed that German chamomile and Roman chamomile are closely related to Chrysanthemum nankingense. CONCLUSION: This work provides the first insights into terpenoid biosynthesis in two species of chamomile. The candidate unigenes related to terpenoid biosynthesis will be important in molecular breeding approaches to modulate the essential oil composition of Matricaria recutita and Chamaemelum nobile.

Circular RNA hsa_circ_0030018 acts as a sponge of miR-599 to aggravate esophageal carcinoma progression by regulating ENAH expression.

Esophageal carcinoma (EC) bears one of the most rapid-growing incidences in cancers, which also has the highest mortality rate worldwide. Multiple studies have authenticated that circular RNAs (circRNAs) significantly work on the progression of cancers. circRNA hsa_circ_0030018 was also verified to exert functions on the development of glioma previously. Nevertheless, the biological function of hsa_circ_0030018 in EC has not been well elucidated yet. In the present study, the results displayed the expression of hsa_circ_0030018 was dramatically increased in EC cells. Inhibition of has_circ_0030018 suppressed cell proliferation, migration, and epithelial-mesenchymal transition (EMT) process in EC. Based on molecular mechanism assays, has_circ_0030018 served as a sponge of miR-599. Enabled homolog (ENAH), which exhibited high expression in EC cells, was confirmed to be a downstream target gene of miR-599. Additionally, has_circ_0030018 positively regulated ENAH expression while miR-599 negatively regulated ENAH expression. Finally, by employing rescue assays, ENAH deficiency partially counteracted the promoting function of miR-599 silence on cell proliferation, migration, and EMT process in EC cotransfected with sh- has_circ_0030018#1 cells. In conclusion, hsa_circ_0030018 acted as a sponge of miR-599 to aggravate EC progression by regulating ENAH expression. Therefore, hsa_circ_0030018 might serve as a promising biomarker and therapeutic target for EC.

Identification of a cellularly active SIRT6 allosteric activator.

SIRT6, a member of the SIRT deacetylase family, is responsible for deacetylation of histone H3 Nε-acetyl-lysines 9 (H3K9ac) and 56 (H3K56ac). As a tumor suppressor, SIRT6 has frequently been found to have low expression in various cancers. Here, we report the identification of MDL-800, a selective SIRT6 activator. MDL-800 increased the deacetylase activity of SIRT6 by up to 22-fold via binding to an allosteric site; this interaction led to a global decrease in H3K9ac and H3K56ac levels in human hepatocellular carcinoma (HCC) cells. Consequently, MDL-800 inhibited the proliferation of HCC cells via SIRT6-driven cell-cycle arrest and was effective in a tumor xenograft model. Together, these data demonstrate that pharmacological activation of SIRT6 is a potential therapeutic approach for the treatment of HCC. MDL-800 is a first-in-class small-molecule cellular SIRT6 activator that can be used to physiologically and pathologically investigate the roles of SIRT6 deacetylation.

Effect of BMI on blood value of patients on HCG day with IUI treatment.

BACKGROUND: This study aims to analyze the effect of the body mass index (BMI) on E2, P and LH values in females who received intrauterine insemination (IUI) treatment on human chorionic gonadotropin (HCG) day. METHODS: A total of 2319 cycles of IUI-assisted pregnancy treatment were selected in our hospital. Based on the BMI, female infertility patients are divided into three groups: normal weight group, overweight and obese group. RESULTS: For patients with natural cycles and ≤ 35 years old, there were 440, 178 and 197 cases in the three groups, respectively. For patients with natural cycles and > 35 years old, there were 90, 83 and 81 cycles in the three groups, respectively. For patients with induced ovulation cycle and ≤ 35 years old, there were 425, 203 and 516 cases in the three groups, respectively. For patients with induced ovulation cycle and > 35 years old, there were 26, 26 and 54 cases in the three groups, respectively. CONCLUSION: When a patient is ≤35 years old, the BMI affects the E2, LH and P values on the day of artificial insemination. However, the BMI is negatively correlated with E2, LH and P in IUI on HCG day. After controlling for age and assisted pregnancy, the correlation analysis revealed that the BMI is negatively correlated with hormone E2 and LH. The higher the BMI was, the lower the levels of hormones E2, LH and P became. However, in the present study, the BMI did not significantly improve the clinical pregnancy rate of patients who received IUI.

The characteristics of the frequent exacerbator with chronic bronchitis phenotype and non-exacerbator phenotype in patients with chronic obstructive pulmonary disease: a meta-analysis and system review.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) patients with different phenotypes show different clinical characteristics. Therefore, we conducted a meta-analysis to explore the clinical characteristics between the non-exacerbator (NE) phenotype and the frequent exacerbator with chronic bronchitis (FE-CB) phenotype among patients with COPD. METHODS: CNKI, Wan fang, Chongqing VIP, China Biology Medicine disc, PubMed, Cochrane Library, and EMBASE databases were searched from the times of their inception to April 30, 2019. All studies that reported the clinical characteristics of the COPD phenotypes and which met the inclusion criteria were included. The quality assessment was analyzed by Cross-Sectional/Prevalence Study Quality recommendations. The meta-analysis was carried out using RevMan5.3. RESULTS: Ten cross-sectional observation studies (n = 8848) were included. Compared with the NE phenotype, patients with the FE-CB phenotype showed significantly lower forced expiratory volume in 1 s percent predicted (FEV1%pred) (mean difference (MD) -8.50, 95% CI -11.36--5.65, P < 0.001, I2 = 91%), forced vital capacity percent predicted (FVC%pred) [MD - 6.69, 95% confidence interval (CI) -7.73--5.65, P < 0.001, I2 = 5%], and forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) (MD -3.76, 95% CI -4.58--2.95,P < 0.001, I2 = 0%); in contrast, Charlson comorbidity index (MD 0.47, 95% CI 0.37-0.58, P < 0.001, I2 = 0], COPD assessment test (CAT) score (MD 5.61, 95% CI 4.62-6.60, P < 0.001, I2 = 80%), the quantity of cigarettes smoked (pack-years) (MD 3.09, 95% CI 1.60-4.58, P < 0.001, I2 = 41%), exacerbations in previous year (2.65, 95% CI 2.32-2.97, P < 0.001, I2 = 91%), modified Medical British Research Council (mMRC) score (MD 0.72, 95% CI 0.63-0.82, P < 0.001, I2 = 57%), and body mass index (BMI), obstruction, dyspnea, exacerbations (BODEx) (MD 1.78, 95% CI 1.28-2.28, P < 0.001, I2 = 91%), I2 = 34%) were significantly higher in patients with FE-CB phenotype. No significant between-group difference was observed with respect to BMI (MD-0.14, 95% CI -0.70-0.42, P = 0.62, I2 = 75%). CONCLUSION: COPD patients with the FE-CB phenotype had worse pulmonary function and higher CAT score, mMRC scores, frequency of acute exacerbations, and the quantity of cigarettes smoked (pack-years) than those with the NE phenotype.

Long noncoding RNA CCAT2 functions as a competitive endogenous RNA to regulate FOXC1 expression by sponging miR-23b-5p in lung adenocarcinoma.

Long noncoding RNA (lncRNA) may regulate the process of tumor formation. Although lncRNA CCAT2 has been identified as a key point in many diseases, its pathophysiological mechanism in lung adenocarcinoma remains unknown. We measured the expression level of CCAT2 in lung adenocarcinoma cells and normal lung epithelial cell line BEAS-2B by quantitative real-time polymerase chain reaction (qRT-PCR). As well, cell migration and proliferation were detected by transwell detection and CCK8 assay. At the same time, the new target point of CCAT2 was confirmed with bioinformatics analysis and dual-luciferase reporter assay. In addition, potential mechanisms were studied by Western blot analysis and RNA immunoprecipitation (RIP) analysis. The expression of CCAT2 was upregulated obviously in lung adenocarcinoma cells. Cell function analysis showed that upregulation of CCAT2 significantly promoted cell proliferation and migration, and reduction of CCAT2 inhibited cell migration and proliferation. In addition, CCAT2 positively regulated the expression of FOXC1 by competitive binding with miR-23b-5p. These findings indicated that CCAT2 may act as a competitive endogenous RNA (ceRNA) to regulate FOXC1 expression by competitively binding miR-23b-5p in lung adenocarcinoma.

One-Step Route Synthesized Co2 P/Ru/N-Doped Carbon Nanotube Hybrids as Bifunctional Electrocatalysts for High-Performance Li-O2 Batteries.

The large-scale commercial application of lithium-oxygen batteries (LOBs) is overwhelmed by the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) associated with insoluble and insulated Li2 O2 . Herein, an elaborate design on a highly catalytic LOBs cathode constructed by N-doped carbon nanotubes (CNT) with in situ encapsulated Co2 P and Ru nanoparticles is reported. The homogeneously dispersed Co2 P and Ru catalysts can effectively modulate the formation and decomposition behavior of Li2 O2 during discharge/charge processes, ameliorating the electronically insulating property of Li2 O2 and constructing a homogenous low-impedance Li2 O2 /catalyst interface. Compared with Co/CNT and Ru/CNT electrodes, the Co2 P/Ru/CNT electrode delivers much higher oxygen reduction triggering onset potential and higher ORR and OER peak current and integral areas, showing greatly improved ORR/OER kinetics due to the synergistic effects of Co2 P and Ru. Li-O2 cells based on the Ru/Co2 P/CNT electrode demonstrate improved ORR/OER overpotential of 0.75 V, excellent rate capability of 12 800 mAh g-1 at 1 A g-1 , and superior cycle stability for more than 185 cycles under a restricted capacity of 1000 mAh g-1 at 100 mA g-1 . This work paves an exciting avenue for the design and construction of bifunctional catalytic cathodes by coupling metal phosphides with other active components in LOBs.

Lipidomics coupled with pathway analysis characterizes serum metabolic changes in response to potassium oxonate induced hyperuricemic rats.

BACKGROUND: Hyperuricemia as a metabolic disease is usually associated with lipid metabolic disorder. The purpose of this study is to identify potential lipid biomarkers and provide the evidence for the relationship between hyperuricemia and lipid-related diseases. METHODS: Lipidomics-a specialized study of lipid metabolites-has become a highly sensitive and powerful tool for biomarker discovery. In this work, an ultra-performance liquid chromatography-quadruole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS)-based on Lipidomics approach was employed to investigate serum samples from potassium oxonate-treated rats to find potential biomarkers. Principal component analysis (PCA) was used to analyze the MS data to assess the establishment of hyperuricemia model. Orthogonal partial least-squares discriminant analysis (OPLS-DA) in combination with independent samples t-test was performed for biomarker selection and identification. RESULTS: Thirteen potential biomarkers in rat serum were identified in the screen, and two abnormal metabolism pathways were found, namely glycerolphospholipid metabolism and glycosylphosphatidylinositol-anchored protein biosynthesis. CONCLUSIONS: In this work, the Lipidomics approach based on UPLC-Q-TOF/MS was employed to investigate serum metabolic changes in the rat model, 13 potential biomarkers related to hyperuricemia were identified, primarily involved in glycerolphospholipid metabolism and glycosylphosphatidylinositol-anchored protein biosynthesis. Abnormal glycerophospholipid metabolism pathway may be associated with lipid metabolism disorder caused by hyperuricemia, while the relationship between hyperuricemia and glycosylphosphatidylinositol-anchored protein biosynthesis needs further study.

[Effect of Scutellariae Radix on expression of inflammatory cytokine protein and gene in lung of mice with viral pneumonia caused by influenza virus FM1 infection].

Mice models of viral pneumonia were induced by pulmonary adaptive strain FM1 of influenza A virus in Asian mice.RT-PCR and immunohistochemistry were used to dynamically observe the effect of Scutellariae Radix on the protein and gene expression of inflammatory cytokine in the lungs of the model mice infected by influenza virus FM1 at different phases. The partial mechanism of Scutellariae Radix in repairing the immune inflammatory damage of target organs of pneumonia caused by influenza virus was further explored. The results showed that Scutellariae Radix reduced protein and gene expression of proinflammatory cytokines tumor necrosis factor( TNF-α),interleukin IL-1,IL-6 in lung tissues from 3 rd to 5 th day after infection,and increased protein and gene expression of IL-10 and IFN-γ in lung tissues on the 5 th day after infection. Scutellariae Radix may inhibit excessive release of pro-inflammatory cytokines and promote the expression of anti-inflammatory cytokines,thereby inhibiting the systemic inflammatory response syndrome,reducing the immunoinflammatory pathological damage of lung caused by influenza virus FM1 infection,and promoting lung repair of tissue inflammatory lesions.

Joint Transmit Power Allocation and Splitting for SWIPT Aided OFDM-IDMA in Wireless Sensor Networks.

In this paper, we propose to combine Orthogonal Frequency Division Multiplexing-Interleave Division Multiple Access (OFDM-IDMA) with Simultaneous Wireless Information and Power Transfer (SWIPT), resulting in SWIPT aided OFDM-IDMA scheme for power-limited sensor networks. In the proposed system, the Receive Node (RN) applies Power Splitting (PS) to coordinate the Energy Harvesting (EH) and Information Decoding (ID) process, where the harvested energy is utilized to guarantee the iterative Multi-User Detection (MUD) of IDMA to work under sufficient number of iterations. Our objective is to minimize the total transmit power of Source Node (SN), while satisfying the requirements of both minimum harvested energy and Bit Error Rate (BER) performance from individual receive nodes. We formulate such a problem as a joint power allocation and splitting one, where the iteration number of MUD is also taken into consideration as the key parameter to affect both EH and ID constraints. To solve it, a sub-optimal algorithm is proposed to determine the power profile, PS ratio and iteration number of MUD in an iterative manner. Simulation results verify that the proposed algorithm can provide significant performance improvement.

Exact Distributions of Finite Random Matrices and Their Applications to Spectrum Sensing.

The exact and simple distributions of finite random matrix theory (FRMT) are critically important for cognitive radio networks (CRNs). In this paper, we unify some existing distributions of the FRMT with the proposed coefficient matrices (vectors) and represent the distributions with the coefficient-based formulations. A coefficient reuse mechanism is studied, i.e., the same coefficient matrices (vectors) can be exploited to formulate different distributions. For instance, the same coefficient matrices can be used by the largest eigenvalue (LE) and the scaled largest eigenvalue (SLE); the same coefficient vectors can be used by the smallest eigenvalue (SE) and the Demmel condition number (DCN). A new and simple cumulative distribution function (CDF) of the DCN is also deduced. In particular, the dimension boundary between the infinite random matrix theory (IRMT) and the FRMT is initially defined. The dimension boundary provides a theoretical way to divide random matrices into infinite random matrices and finite random matrices. The FRMT-based spectrum sensing (SS) schemes are studied for CRNs. The SLE-based scheme can be considered as an asymptotically-optimal SS scheme when the dimension K is larger than two. Moreover, the standard condition number (SCN)-based scheme achieves the same sensing performance as the SLE-based scheme for dual covariance matrix K = 2 . The simulation results verify that the coefficient-based distributions can fit the empirical results very well, and the FRMT-based schemes outperform the IRMT-based schemes and the conventional SS schemes.