Impact of Beam Misalignment on Hybrid Beamforming NOMA for mmWave Communications

This paper analyzes the effect of beam misalignment on rate performance in downlink of hybrid beamforming-based non-orthogonal multiple access (HB-NOMA) systems. First an HB-NOMA framework is designed in multiuser millimeter wave (mmWave) communications. A sum-rate maximization problem is formulated for HB-NOMA, and an algorithm is introduced to design digital and analog precoders and efficient power allocation. Then, regarding perfectly aligned line-of-sight (LoS) channels, a lower bound for the achievable rate is derived. Next, when the users experience misaligned LoS or non-LoS (NLoS) channels, the impact of beam misalignment is evaluated. To this end, a misalignment factor is modeled and each misaligned effective channel is described in terms of the perfectly aligned effective channel parameters and the misalignment factor. Further, a lower bound for the achievable rate is extracted. We then derive an upper bound for the rate gap expression between the aligned and misaligned HB-NOMA systems. The analyses reveal that a large misalignment can remarkably degrade the rate. Extensive numerical simulations are conducted to verify the findings

Lens-Based Millimeter Wave Reconfigurable Antenna NOMA

This paper proposes a new multiple access technique based on the millimeter wave lens-based reconfigurable antenna systems. In particular, to support a large number of groups of users with different angles of departures (AoDs), we integrate recently proposed reconfigurable antenna multiple access (RAMA) into non-orthogonal multiple access (NOMA). The proposed technique, named reconfigurable antenna NOMA (RA-NOMA), divides the users with respect to their AoDs and channel gains. Users with different AoDs and comparable channel gains are served via RAMA while users with the same AoDs but different channel gains are served via NOMA. This technique results in the independence of the number of radio frequency chains from the number of NOMA groups. Further, we derive the feasibility conditions and show that the power allocation for RA-NOMA is a convex problem. We then derive the maximum achievable sum-rate of RA-NOMA. Simulation results show that RA-NOMA outperforms conventional orthogonal multiple access (OMA) as well as the combination of RAMA with the OMA techniques

Non-Orthogonal Multiple Access Based on Hybrid Beamforming for mmWave Systems

This paper aims to study the utilization of non-orthogonal multiple access (NOMA) in hybrid beamforming (HB) multiuser systems, called HB-NOMA, to serve a large number of mobile users. First, a sum-rate expression for the HB-NOMA problem is formulated. Second, an effective algorithm is proposed to maximize the sum-rate. Then, a lower bound is derived under two cases: i) the angle between the effective channel vectors of the MU with the highest channel gain and other MUs located inside a cluster is zero (or close to it) which is denoted by perfect correlation, and ii) this angle is non-zero, which we denote by imperfect correlation. For the second case, the relationship between the effective channels of two HB-NOMA users is modeled. The lower bound for the first case indicates that only the presence of inter-cluster interference and the use of an analog precoder negatively impact the sum-rate. However, in the case of imperfect correlation, which is more realistic, an inefficient MU cluster, can cause severe intra-cluster interference in the network. To verify our findings, numerical simulations have been conducted

Reconfigurable Antennas in mmWave MIMO Systems

The key obstacle to achieving the full potential of the millimeter wave (mmWave) band has been the poor propagation characteristics of wireless signals in this band. One approach to overcome this issue is to use antennas that can support higher gains while providing beam adaptability and diversity, i.e., reconfigurable antennas. In this article, we present a new architecture for mmWave multiple-input multiple-output (MIMO) communications that uses a new class of reconfigurable antennas. More specifically, the proposed lens-based antennas can support multiple radiation patterns while using a single radio frequency chain. Moreover, by using a beam selection network, each antenna beam can be steered in the desired direction. Further, using the proposed reconfigurable antenna in a MIMO architecture, we propose a new signal processing algorithm that uses the additional degrees of freedom provided by the antennas to overcome propagation issues at mmWave frequencies. Our simulation results show that the proposed reconfigurable antenna MIMO architecture significantly enhances the performance of mmWave communication systems

ROLE OF HETEROCHROMATIN VARIATION IN THE LONGEVITY AND GENE EXPRESSION PROFILES OF HETEROCHROMATIC AND AGING-ASSOCIATED GENES IN D. MELANOGASTER

This study aimed to explore the effects of changes in heterochromatin levels on the process of aging in D. melanogaster. X/O and XXY karyotypes, lacking and carrying an added copy of Y chromosome, respectively, were generated, and their average lifespan relative to that of the normal XY males and XX females was measured. My goal was to see if changing the heterochromatin levels would impact the longevity of these karyotypes. Next, the expression profiles of the heterochromatic and aging genes in different karyotypes of the fruit fly models were studies. The expression profiles of the heterochromatic and aging genes differentially varied between X/O vs XY males, and XX vs XXY females from 2-days y1/Dp(1;Y)Bs stock. The differential gene expression patterns were confirmed between the same karyotypes at 60 days, as well as between the Df(2R)Ms2-10/CyO, S males and females which carried heterochromatic deletion from the right arm of chromosome 2

ROLE OF HETEROCHROMATIN VARIATION IN THE LONGEVITY AND GENE EXPRESSION PROFILES OF HETEROCHROMATIC AND AGING-ASSOCIATED GENES IN D. MELANOGASTER

This study aimed to explore the effects of changes in heterochromatin levels on the process of aging in D. melanogaster. X/O and XXY karyotypes, lacking and carrying an added copy of Y chromosome, respectively, were generated, and their average lifespan relative to that of the normal XY males and XX females was measured. My goal was to see if changing the heterochromatin levels would impact the longevity of these karyotypes. Next, the expression profiles of the heterochromatic and aging genes in different karyotypes of the fruit fly models were studies. The expression profiles of the heterochromatic and aging genes differentially varied between X/O vs XY males, and XX vs XXY females from 2-days y1/Dp(1;Y)Bs stock. The differential gene expression patterns were confirmed between the same karyotypes at 60 days, as well as between the Df(2R)Ms2-10/CyO, S males and females which carried heterochromatic deletion from the right arm of chromosome 2

Prevalence of cagA, cagT, cagE, vacA and hrgA genes in Helicobacter pylori strains isolated from patients with gastric cancer in Karaj city, 2016

Background: It is estimated that approximately half of the planet's population is infected with Helicobacter pylori and 70-60 of the infections in the Western countries are caused by cagA-positive strains. The aim of this study was to determine the frequency of cagA, cagT, cagE, vacA and hrgA genes in H. pylori isolated from patients with gastric cancer. Materials and Methods: A total of 50 non-repetitive biopsy samples were collected from patients undergoing endoscopy in the endoscopic center of the Shahid Fayaz Hospital in Karaj. The presence of cagA, cagT, cagE, vacA and hrgA genes was determined using the multiplex PCR method. Results: Of the 50 gastric biopsies, 44 samples (88) were positive for the presence of various virulence genes. The molecular analysis of virulence factors showed that the prevalence rates of cagA, cagT, cagE, vacA and hrgA genes were 16 (32), 8 (16), 13 (26), 7 (14) and 17 (34), respectively. There was a significant relationship between sex, smoking and gastric ulcer with some genes, but no significant relationship was found between the family history and age group with any of the genes. Conclusion: The presence of various pathogenic genes has a significant effect on gastric ulcer, duodenal ulcer and gastric cancer. The effects of other genes, such as hrgA, are important in tissue damage and inflammatory responses

Detrimental effects of cerium oxide nanoparticles on testis, sperm parameters quality, and in vitro fertilization in mice: An experimental study

Background: Cerium oxide nanoparticles (CeO2 NPs) as an important nanomaterial have a wide range of applications in many fields and human beings’ exposure to this nanomaterial is unavoidable. The effects of CeO2 NPs on the male reproductive system are controversial. Objective: To determine the effects of the administration of CeO2 NPs on the testis tissue, sperm parameters, and in vitro fertilization (IVF) in mice. Materials and Methods: Twenty-four male mice were divided into three groups (n = 8/each): one control and two experimental groups receiving CeO2 NPs at doses of 50 and 100 mg/kg body weight, respectively, for 35 days. At the end of the experiment, the diameter of seminiferous tubules (SNTs), epithelial height of SNTs, spermiogenesis index in testes, sperm parameters (count, motility, viability, and morphology), sperm chromatin condensation, DNA integrity, and IVF assays were analyzed. Results: Histological results showed that the tubular diameter, the epithelial height of the SNTs, and the spermiogenesis index were significantly decreased in the experimental groups receiving CeO2 NPs. All sperm parameters in the experimental groups were significantly reduced and, additionally, the percentages of immature sperms and sperms with DNA damage were significantly increased in groups treated with CeO2 NPs compared to the control. Furthermore, the rates of IVF and in vitro embryo development were decreased. Conclusion: Collectively, the current study showed that oral administration of CeO2 NPs in mice had detrimental effects on the male reproductive system through inducing testicular tissue alterations, decreasing sperm parameters quality, and also diminishing the IVF rate and in vitro embryonic development. Key words: Cerium oxide, Testis, Sperm, Fertilization, Mice