Cross-Layer Design in Dynamic Spectrum Sharing Systems

We consider a dynamic spectrum sharing system consisting of a primary user, whose licensed spectrum is allowed to be accessed by a secondary user as long as it does not violate the prescribed interference limit inflicted on the primary user. Assuming the Nakagami-m block-fading environment, we aim at maximizing the performance of secondary user's link in terms of average spectral efficiency (ASE) and error performance under the specified packet error rate (PER) and average interference limit constraints. To this end, we employ a cross-layer design policy which combines adaptive power and coded discrete M-QAM modulation scheme at the physical layer with a truncated automatic repeat request (ARQ) protocol at the data link layer, and simultaneously satisfies the aforementioned constraints. Numerical results affirm that the secondary link of spectrum sharing system combining ARQ with adaptive modulation and coding (AMC) achieves significant gain in ASE depending on the maximum number of retransmissions initiated by the ARQ protocol. The results further indicate that the ARQ protocol essentially improves the packet loss rate performance of the secondary link

Optical coherence tomography enables imaging of tumor initiation in the TAg-RB mouse model of retinoblastoma

PURPOSE: Retinoblastoma is the most common primary intraocular malignancy in children. Although significant advances in treatment have decreased mortality in recent years, morbidity continues to be associated with these therapies, and therefore, there is a pressing need for new therapeutic options. Transgenic mouse models are popular for testing new therapeutics as well as studying the pathophysiology of retinoblastoma. The T-antigen retinoblastoma (TAg-RB) model has close molecular and histological resemblance to human retinoblastoma tumors; these mice inactivate pRB by retinal-specific expression of the Simian Virus 40 T-antigens. Here, we evaluated whether optical coherence tomography (OCT) imaging could be used to document tumor growth in the TAg-RB model from the earliest stages of tumor development. METHODS: The Micron III rodent imaging system was used to obtain fundus photographs and OCT images of both eyes of TAg-RB mice weekly from 2 to 12 weeks of age and at 16 and 20 weeks of age to document tumor development. Tumor morphology was confirmed with histological analysis. RESULTS: Before being visible on funduscopy, hyperreflective masses arising in the inner nuclear layer were evident at 2 weeks of age with OCT imaging. After most of these hyperreflective cell clusters disappeared around 4 weeks of age, the first tumors became visible on OCT and funduscopy by 6 weeks. The masses grew into discrete, discoid tumors, preferentially in the periphery, that developed more irregular morphology over time, eventually merging and displacing the inner retinal layers into the vitreous. CONCLUSIONS: OCT is a non-invasive imaging modality for tracking early TAg-RB tumor growth in vivo. Using OCT, we characterized TAg-positive cells as early as 2 weeks, corresponding to the earliest stages at which tumors are histologically evident, and well before they are evident with funduscopy. Tracking tumor growth from its earliest stages will allow better analysis of the efficacy of novel therapeutics and genetic factors tested in this powerful mouse model

Scale Effects of Footings on Geocell Reinforced Sand Using Large-Scale Tests

The scale effect on bearing capacity of shallow footings supported by unreinforced granular soils has been evaluated extensively. However, the subject has not been addressed for shallow footings on geocell-reinforced granular soils. In this study, load-settlement characteristic of large square footings is investigated by performing large-scale loading tests on unreinforced and geocell-reinforced granular soils. The effects of footing width (B), soil relative density of soil (Dr), and reinforcement depth (u) have been investigated. The test results show that the scale effects exist in geocell-reinforced soils, like unreinforced soils, and the behavior of small-scale models of footings cannot be directly related to the behavior of full-scale footings due to the difference between initial conditions of tests and the initial state of mean stresses in the soil beneath the footings having different dimensions. Large footings create higher mean stresses in the soil, resulting in low soil friction angle and initial conditions of the test approach to the critical state lines. The results of tests indicate that model experiments should be conducted on low-density soil for better prediction of the behavior of full-scale footings, otherwise, the predicted behavior of full-scale footings does not seem conservative

The relationship between genetic variants associated with primary ovarian insufficiency and lipid profile in women recruited from MASHAD cohort study

Background and aim: Primary Ovarian Insufficiency (POI) is defined by the occurrence of menopause before the age of 40 years. It is often associated with cardiovascular disease (CVD). The purpose of this study was to explore the relationship between POI-associated genotypes cardiometabolic disorder risk factors. Methods: One hundred seventeen women with POI and one hundred eighty-three healthy women without POI were recruited in this study. DNA was extracted and analyzed using ASO-PCR or Tetra ARMS-PCR. Lipid profiles were also assessed. Results: Multivariate logistic regression analysis showed that individuals with GG vs. TT genotype of the rs1046089 SNP were more likely to have a higher serum LDL (p = 0.03) compared to the control group. There was also a significant association between low serum HDL and rs2303369 and rs4806660 SNP genotypes in the POI group. In the POI group, the percentage of those with high total cholesterol was lower in those with a CC genotype compared to those with a TT genotype (p = 0.03). Conclusion: Some SNPs reported to be associated with POI appear to be independently associated with dyslipidemia. These results may be helpful to identify subjects with POI who may be susceptible to CVD

Cross-Layer Design for Interference-Limited Spectrum Sharing Systems

In this paper, we consider a dynamic spectrum sharing system consisting of a primary user, whose licensed spectrum is allowed to be accessed by a secondary user as long as it does not violate the prescribed interference limit inflicted on the primary user. Assuming the Nakagami-m block-fading environment, we aim at maximizing the performance of secondary user's link in terms of average spectral efficiency (ASE) and error performance under the specified packet error rate (PER) and average interference limit constraints. To this end, we employ a cross-layer design policy which combines adaptive power and coded discrete M-QAM modulation scheme at the physical layer with a truncated automatic repeat request (ARQ) protocol at the data link layer, and simultaneously satisfies the aforementioned constraints. Numerical results affirm that the secondary link of spectrum sharing system combining ARQ with adaptive modulation and coding (AMC) achieves significant gain in ASE depending on the maximum number of retransmissions initiated by the ARQ protocol. The results further indicate that the ARQ protocol essentially improves the packet loss rate performance of the secondary link

Wavelet-based downlink scheduling and resource allocation for long-term evolution cellular systems

This study proposes the use of wavelet transform in long-term evolution (LTE) cellular systems. Mathematical expressions are derived to represent data rate in LTE downlink transmission based on Wavelet and Fourier Transforms. Furthermore, a comparison between these two systems is provided. Simulation results show the proposed orthogonal wavelet division multiplexing (OWDM) approach outperforms the traditional orthogonal frequency division multiplexing-based systems. The data rate can also be increased by the amount of CyclicPrefix/SymbolTime%, as there is no need for a channel prefix in an OWDM-based system.</p

Novel LCL filter for non-isolated photovoltaic inverters with CM current trapping capability for weak grids

© 2018 IEEE. In this work, a novel LCL filter topology for non-isolated Photovoltaic (PV) applications is developed. This topology has the ability to trap the High-Frequency (HF) Common Mode (CM) current inside the PV inverter. Consequently, suppressing the ground leakage current. Furthermore, the proposed solution is immune to ground leakage current resonance issues (i.e. effective for applications where the utility grid is characterized as a weak grid). Moreover, the theoretical analyses were validated on a 10 kW grid-connected PV system. The results demonstrated that at resonance conditions, the proposed system reduced the leakage current root-mean-square (RMS) value from 1 A to 25 mA. Thus, satisfying the VDE standard's leakage current limit.This publication was made possible by NPRP grant # [X-033-2-007] from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors

Optical coherence tomography enables imaging of tumor initiation in the TAg-RB mouse model of retinoblastoma

PURPOSE: Retinoblastoma is the most common primary intraocular malignancy in children. Although significant advances in treatment have decreased mortality in recent years, morbidity continues to be associated with these therapies, and therefore, there is a pressing need for new therapeutic options. Transgenic mouse models are popular for testing new therapeutics as well as studying the pathophysiology of retinoblastoma. The T-antigen retinoblastoma (TAg-RB) model has close molecular and histological resemblance to human retinoblastoma tumors; these mice inactivate pRB by retinal-specific expression of the Simian Virus 40 T-antigens. Here, we evaluated whether optical coherence tomography (OCT) imaging could be used to document tumor growth in the TAg-RB model from the earliest stages of tumor development. METHODS: The Micron III rodent imaging system was used to obtain fundus photographs and OCT images of both eyes of TAg-RB mice weekly from 2 to 12 weeks of age and at 16 and 20 weeks of age to document tumor development. Tumor morphology was confirmed with histological analysis. RESULTS: Before being visible on funduscopy, hyperreflective masses arising in the inner nuclear layer were evident at 2 weeks of age with OCT imaging. After most of these hyperreflective cell clusters disappeared around 4 weeks of age, the first tumors became visible on OCT and funduscopy by 6 weeks. The masses grew into discrete, discoid tumors, preferentially in the periphery, that developed more irregular morphology over time, eventually merging and displacing the inner retinal layers into the vitreous. CONCLUSIONS: OCT is a non-invasive imaging modality for tracking early TAg-RB tumor growth in vivo. Using OCT, we characterized TAg-positive cells as early as 2 weeks, corresponding to the earliest stages at which tumors are histologically evident, and well before they are evident with funduscopy. Tracking tumor growth from its earliest stages will allow better analysis of the efficacy of novel therapeutics and genetic factors tested in this powerful mouse model

Edge Computing for Low Delay to Cache and Transfer Electronic Medical Records

. A new method is proposed to decrease the transmission delay of visual and non-visual medical records by using edge computing and Dynamic Vision Sensing technologies. The simulation results show that the proposed scheme can decrease the transmission delay by 89.15% to 93.23%. The maximum number of patients who can be served by edge devices is analysed.</p