4,136 research outputs found
Ergodic Achievable Rate Analysis and Optimization of RIS-assisted Millimeter-Wave MIMO Communication Systems
Reconfigurable intelligent surfaces (RISs) have emerged as a prospective
technology for next-generation wireless networks due to their potential in
coverage and capacity enhancement. Previous works on achievable rate analysis
of RIS-assisted communication systems have mainly focused on the
rich-scattering environment where Rayleigh and Rician channel models can be
applied. This work studies the ergodic achievable rate of RIS-assisted
multiple-input multiple-output communication systems in millimeter-wave band
with limited scattering under the Saleh-Valenzuela channel model. Firstly, we
derive an upper bound of the ergodic achievable rate by means of majorization
theory and Jensen's inequality. The upper bound shows that the ergodic
achievable rate increases logarithmically with the number of antennas at the
base station (BS) and user, the number of the reflection units at the RIS, and
the eigenvalues of the steering matrices associated with the BS, user and RIS.
Then, we aim to maximize the ergodic achievable rate by jointly optimizing the
transmit covariance matrix at the BS and the reflection coefficients at the
RIS. Specifically, the transmit covariance matrix is optimized by the
water-filling algorithm and the reflection coefficients are optimized using the
Riemannian conjugate gradient algorithm. Simulation results validate the
effectiveness of the proposed optimization algorithms.Comment: 30 pages, 11 figure
How to Differentiate between Near Field and Far Field: Revisiting the Rayleigh Distance
Future wireless communication systems are likely to adopt extremely large
aperture arrays and millimeter-wave/sub-THz frequency bands to achieve higher
throughput, lower latency, and higher energy efficiency. Conventional wireless
systems predominantly operate in the far field (FF) of the radiation source of
signals. As the array size increases and the carrier wavelength shrinks,
however, the near field (NF) becomes non-negligible. Since the NF and FF differ
in many aspects, it is essential to distinguish their corresponding regions. In
this article, we first provide a comprehensive overview of the existing NF-FF
boundaries, then introduce a novel NF-FF demarcation method based on effective
degrees of freedom (EDoF) of the channel. Since EDoF is intimately related to
spectral efficiency, the EDoF-based border is able to characterize key channel
performance more accurately, as compared with the classic Rayleigh distance.
Furthermore, we analyze the main features of the EDoF-based NF-FF boundary and
provide insights into wireless system design
Airborne Polarimetric Remote Sensing for Atmospheric Correction
The problem, whose targets can not be effectively identified for airborne remote sensing images, is mainly due to the atmospheric scattering effect. This problem is necessary to be overcome. According to the statistical evaluations method and the different characteristics of polarization between the objects radiance and atmospheric path radiation, a new atmospheric correction method for airborne remote sensing images was proposed. Using this new method on the airborne remote sensing images which acquired on the north coast areas of China during the haze weather, we achieved a high quality corrected atmosphere-free image. The results demonstrate the power of the method on the harbor area. The results show that the algorithm, improving image contrast and image information entropy, can effectively identify the targets after atmospheric correction. The image information entropy was enhanced from 5.59 to 6.62. The research provides a new and effective atmospheric correction technical approach for the airborne remote sensing images
Effect of edaravone-urinary kallidinogenase combination treatment on acute cerebral infarction
Purpose: To investigate the curative effect of edaravone in combination with urinary kallidinogenase in the treatment of acute cerebral infarction and its effect on serum high-sensitivity C-reactive protein (hs-CRP) and interleukin (IL).Methods: One hundred and eighty patients with acute cerebral infarction (ACI) who were on admission from March 2015 to July 2016 participated in this study as research subjects. They were assigned to study group (59 patients) and control group (59 patients). Edaravone and conventional treatment were administered to the control group. In contrast, in addition to conventional treatment, the study group was given edaravone in combination with urinary kallidinogenase. Clinical effects, neurological function and serum IL-17 and hs-CRP levels in the two groups were determined.Results: The overall response of the study group was significantly higher than that of the control group (p < 0.05). Scores in the National Institute of Health stroke scale (NIHSS) were reduced in both groups, and modified Barthel index (MBI) of both groups remarkably increased, when compared to values before treatment. Improvements in NIHSS score and MBI of the study group were higher than those of the control group (p < 0.05). Serum IL-17 and hs-CRP levels declined significantly in the two groups (p < 0.05), but post-treatment serum IL-17 and hs-CRP levels of the study group were significantly reduced, relative to control values (p < 0.05). There were no significant differences in incidence of adverse reactions between the two groups.Conclusion: The use of edaravone in combination with urinary kallidinogenase in the treatment of ACI can significantly reduce serum IL-17 and hs-CRP levels without inducing severe adverse reactions.Keywords: Edaravone, Urinary kallidinogenase, Acute cerebral infarctio
Molybdenum disulfide nanoflowers mediated anti-inflammation macrophage modulation for spinal cord injury treatment
Spinal cord injury (SCI) can cause locomotor dysfunctions and sensory deficits. Evidence shows that functional nanodrugs can regulate macrophage polarization and promote anti-inflammatory cytokine expression, which is feasible in SCI immunotherapeutic treatments. Molybdenum disulfide (MoS2) nanomaterials have garnered great attention as potential carriers for therapeutic payload. Herein, we synthesize MoS2@PEG (MoS2 = molybdenum disulfide, PEG = poly (ethylene glycol)) nanoflowers as an effective carrier for loading etanercept (ET) to treat SCI. We characterize drug loading and release properties of MoS2@PEG in vitro and demonstrate that ET-loading MoS2@PEG obviously inhibits the expression of M1-related pro-inflammatory markers (TNF-α, CD86 and iNOS), while promoting M2-related anti-inflammatory markers (Agr1, CD206 and IL-10) levels. In vivo, the mouse model of SCI shows that long-circulating ET-MoS2@PEG nanodrugs can effectively extravasate into the injured spinal cord up to 96 h after SCI, and promote macrophages towards M2 type polarization. As a result, the ET-loading MoS2@PEG administration in mice can protect survival motor neurons, thus, reducing injured areas at central lesion sites, and significantly improving locomotor recovery. This study demonstrates the anti-inflammatory and neuroprotective activities of ET-MoS2@PEG and promising utility of MoS2 nanomaterial-mediated drug delivery
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Efficient Prodrug Activator Gene Therapy by Retroviral Replicating Vectors Prolongs Survival in an Immune-Competent Intracerebral Glioma Model.
Prodrug activator gene therapy mediated by murine leukemia virus (MLV)-based retroviral replicating vectors (RRV) was previously shown to be highly effective in killing glioma cells both in culture and in vivo. To avoid receptor interference and enable dual vector co-infection with MLV-RRV, we have developed another RRV based on gibbon ape leukemia virus (GALV) that also shows robust replicative spread in a wide variety of tumor cells. We evaluated the potential of GALV-based RRV as a cancer therapeutic agent by incorporating yeast cytosine deaminase (CD) and E. coli nitroreductase (NTR) prodrug activator genes into the vector. The expression of CD and NTR genes from GALV-RRV achieved highly efficient delivery of these prodrug activator genes to RG-2 glioma cells, resulting in enhanced cytotoxicity after administering their respective prodrugs 5-fluorocytosine and CB1954 in vitro. In an immune-competent intracerebral RG-2 glioma model, GALV-mediated CD and NTR gene therapy both significantly suppressed tumor growth with CB1954 administration after a single injection of vector supernatant. However, NTR showed greater potency than CD, with control animals receiving GALV-NTR vector alone (i.e., without CB1954 prodrug) showing extensive tumor growth with a median survival time of 17.5 days, while animals receiving GALV-NTR and CB1954 showed significantly prolonged survival with a median survival time of 30 days. In conclusion, GALV-RRV enabled high-efficiency gene transfer and persistent expression of NTR, resulting in efficient cell killing, suppression of tumor growth, and prolonged survival upon CB1954 administration. This validates the use of therapeutic strategies employing this prodrug activator gene to arm GALV-RRV, and opens the door to the possibility of future combination gene therapy with CD-armed MLV-RRV, as the latter vector is currently being evaluated in clinical trials
Comparison of outcomes between immediate implant-based and autologous reconstruction: 15-year, single-center experience in a propensity score-matched Chinese cohort
Objective: The number of immediate breast reconstruction (IBR) procedures has been increasing in China. This study aimed to investigate the oncological safety of IBR, and to compare the survival and surgical outcomes between implant-based and autologous reconstruction. Methods: Data from patients diagnosed with invasive breast cancer who underwent immediate total breast reconstruction between 2001 and 2016 were retrospectively reviewed. Long-term breast cancer-specific survival (BCSS), disease-free survival (DFS), and locoregional recurrence-free survival (LRFS) were evaluated. Patient satisfaction with the breast was compared between the implant-based and autologous groups. BCSS, DFS, and LRFS were compared between groups after propensity score matching (PSM). Results: A total of 784 IBR procedures were identified, of which 584 were performed on patients with invasive breast cancer (implant-based, n = 288; autologous, n = 296). With a median follow-up of 71.3 months, the 10-year estimates of BCSS, DFS, and LRFS were 88.9% [95% confidence interval (CI) (85.1%–93.0%)], 79.6% [95% CI (74.7%–84.8%)], and 94.0% [95% CI (90.3%–97.8%)], respectively. A total of 124 patients completed the Breast-Q questionnaire, and no statistically significant differences were noted between groups (P = 0.823). After PSM with 27 variables, no statistically significant differences in BCSS, DFS, and LRFS were found between the implant-based (n = 177) and autologous (n = 177) groups. Further stratification according to staging, histological grade, lymph node status, and lymph-venous invasion status revealed no significant survival differences between groups. Conclusions: Both immediate implant-based and autologous reconstruction were reasonable choices with similar long-term oncological outcomes and patient-reported satisfaction among patients with invasive breast cancer in China
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Shear stress regulation of miR-93 and miR-484 maturation through nucleolin.
Pulsatile shear (PS) and oscillatory shear (OS) elicit distinct mechanotransduction signals that maintain endothelial homeostasis or induce endothelial dysfunction, respectively. A subset of microRNAs (miRs) in vascular endothelial cells (ECs) are differentially regulated by PS and OS, but the regulation of the miR processing and its implications in EC biology by shear stress are poorly understood. From a systematic in silico analysis for RNA binding proteins that regulate miR processing, we found that nucleolin (NCL) is a major regulator of miR processing in response to OS and essential for the maturation of miR-93 and miR-484 that target mRNAs encoding Krüppel-like factor 2 (KLF2) and endothelial nitric oxide synthase (eNOS). Additionally, anti-miR-93 and anti-miR-484 restore KLF2 and eNOS expression and NO bioavailability in ECs under OS. Analysis of posttranslational modifications of NCL identified that serine 328 (S328) phosphorylation by AMP-activated protein kinase (AMPK) was a major PS-activated event. AMPK phosphorylation of NCL sequesters it in the nucleus, thereby inhibiting miR-93 and miR-484 processing and their subsequent targeting of KLF2 and eNOS mRNA. Elevated levels of miR-93 and miR-484 were found in sera collected from individuals afflicted with coronary artery disease in two cohorts. These findings provide translational relevance of the AMPK-NCL-miR-93/miR-484 axis in miRNA processing in EC health and coronary artery disease
On Enabling Mobile Crowd Sensing for Data Collection in Smart Agriculture
Smart agriculture enables the efficiency and intelligence of production in physical farm management. Though promising, due to the limitation of the existing data collection methods, it still encounters few challenges that are required to be considered. Mobile Crowd Sensing (MCS) embeds three beneficial characteristics: a) cost-effectiveness, b) scalability, and c) mobility and robustness. With the Internet of Things (IoT) becoming a reality, the smart phones are widely becoming available even in remote areas. Hence, both the MCSs characteristics and the plug and play widely available infrastructure provides huge opportunities for the MCS-enabled smart agriculture.opening up several new opportunities at the application level. In this paper, we extensively evaluate the Agriculture Mobile Crowd Sensing
(AMCS) and provide insights for agricultural data collection schemes. In addition, we provide a comparative study with the existing agriculture data collection solutions and conclude that AMCS has significant benefits in terms of flexibility, collecting implicit data, and low cost requirements. However, we note that AMCSs may still posses limitations in regard to data integrity and quality to be considered as a future work. To this end, we perform a detailed analysis of the challenges and opportunities that concerns the MCS-enabled agriculture by putting forward six potential applications of AMCS-enabled agriculture. Finally, we propose future research and focus on agricultural characteristics, e.g., seasonality and regionality
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