Efficient Constant Envelope Precoding for Massive MU-MIMO Downlink via Majorization-Minimization Method.

The practical implementation of massive multi-user multi-input-multi-output (MU-MIMO) downlink communication systems power amplifiers that are energy efficient; otherwise, the power consumption of the base station (BS) will be prohibitive. Constant envelope (CE) precoding is gaining increasing interest for its capability to utilize low-cost, high-efficiency nonlinear radio frequency amplifiers. Our work focuses on the topic of CE precoding in massive MU-MIMO systems and presents an efficient CE precoding algorithm. This algorithm uses an alternating minimization (AltMin) framework to optimize the CE precoded signal and precoding factor, aiming to minimize the difference between the received signal and the transmit symbol. For the optimization of the CE precoded signal, we provide a powerful approach that integrates the majorization-minimization (MM) method and the fast iterative shrinkage-thresholding (FISTA) method. This algorithm combines the characteristics of the massive MU-MIMO channel with the second-order Taylor expansion to construct the surrogate function in the MM method, in which minimizing this surrogate function is the worst-case of the system. Specifically, we expand the suggested CE precoding algorithm to involve the discrete constant envelope (DCE) precoding case. In addition, we thoroughly examine the exact property, convergence, and computational complexity of the proposed algorithm. Simulation results demonstrate that the proposed CE precoding algorithm can achievean uncoded biterror rate (BER) performance gain of roughly 1dB compared to the existing CE precoding algorithm and has an acceptable computational complexity. This performance advantage also exists when it comes to DCE precoding.

Assessing the environmental impact of phenanthrene in different types of land use based on the binding characteristics with dissolved organic matter.

The binding characteristics of phenanthrene with dissolved organic matter (DOM) were studied by the excitation emission matrix fluorescence spectroscopy with parallel factor analysis in four types of land use which derived from forest (F), meadow (M), cropland (C), and greenhouse (G). The results showed that the humification degree and binding characteristics of phenanthrene with DOM were distinct differences in the four soils. The binding capacities of humic-like components with phenanthrene were stronger than those of protein-like components. The log K derived from the Stern-Volmer equation significantly correlated with the humification degree of DOM (p < 0.05) in different types of land use. Besides, correlation analysis demonstrated that the potential binding index (Fk) obtained from the modified Stern-Volmer model was a more accurate parameter to describe the combination degree of DOM with phenanthrene than log K, which presented a decrease order of C > F > M > G. Therefore, the environmental impact of phenanthrene in different types of land use could be assessed deeply based on the Fk and DOM concentration.

Gonadotropin-releasing hormone agonists for ovarian protection during breast cancer chemotherapy: a systematic review and meta-analysis.

IMPORTANCE: The increasing trend of delaying childbirth means that more women are being diagnosed with breast cancer before having given birth to their desired number of children. Although chemotherapy can significantly improve the prognosis of this population, it also causes ovarian damage, including premature ovarian insufficiency and infertility. Gonadotropin-releasing hormone agonists (GnRHa) have shown promising fertility protective activity in premenopausal women, but their clinical usage remains controversial. OBJECTIVE: Here, we conducted a meta-analysis to assess the efficacy of GnRHa when administered concurrently with chemotherapy that included cyclophosphamide in the prevention of chemotherapy-induced ovarian damage in premenopausal women. EVIDENCE REVIEW: An extensive literature search was performed using the PubMed, Embase, and Cochrane databases. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were determined. FINDINGS: Eleven randomized controlled trials with a total of 1,219 participants were included in the analyses. A significantly higher number of women treated with GnRHa experienced the resumption of ovarian function after chemotherapy than those who did not receive this treatment (OR, 3.04; 95% CI, 1.87-4.94; P < 0.001). Regarding spontaneous pregnancy, a statistically significant difference was observed only in hormone receptor-negative participants (OR, 2.06; 95% CI, 1.03-4.11; P = 0.04). CONCLUSIONS AND RELEVANCE: When treating premenopausal women with breast cancer, the administration of GnRHa concurrently with chemotherapy appeared to improve the resumption rate of ovarian function; however, the spontaneous pregnancy rate only improved in hormone receptor-negative patients. Thus, the use of GnRHa during chemotherapy may represent a feasible strategy for preserving ovarian function in women with breast cancer.

[Periphytic Algae Community Structure and Its Relation to Environment Factors in the Main Stream of the Songhua River from 2014 to 2019].

Periphytic algae are often used as an indicator to evaluate water quality. Here, the community structure of periphytic algae and its relationship with environment factors were analyzed in the main stream of the Songhua River during the summers of 2014 to 2019. The status and trends in ecological water quality were also evaluated based on bioassessments. Phytoplankton species belonging to 4 phyla and 58 genera were recorded, including 28 Bacillariophyta genera, 17 Chlorophyta genera, 10 Cyanophyta genera, and 3 Euglenophyta genera; Bacillariophyta, Chlorophyta, and Cyanophyta accounted for 48.28%, 29.31%, and 17.24% of the community, respectively. Cell densities varied between 1.29×104 and 8.42×104 ind·cm-3, with an average of 4.35×104 ind·cm-3. The dominant genera were Cyclotella, Melosira, Asterionella, Cymbella, Synedra, Pinnularia, Navicula, and Scenedesmus. The physicochemical water quality showed notable changes during the past six-year monitoring period. Specifically, the dissolved oxygen content increased year on year; ammonia nitrogen, total phosphorus, and total nitrogen first increased and then decreased; and, overall, water quality significantly improved in 2019. Relationship between periphytic algae and environmental factors was further examined using redundancy analysis (RDA), which showed that time was the main factor driving the succession of algal community structure. Dissolved oxygen (DO), ammonia nitrogen (NH4+-N), total nitrogen (TN), total phosphorus (TP), five-day biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were also important environmental variables affecting algal community structure.

Polymorphisms in the telomerase reverse transcriptase promoter are associated with risk of breast cancer: A meta-analysis.

AIMS: Recently, the relationship between telomerase reverse transcriptase (TERT) polymorphisms and breast cancer risk has been investigated in several publications. However, the results were inconclusive. In this study, we examined the association between TERT polymorphisms and breast cancer risk by meta-analysis. MATERIALS AND METHODS: The PubMed, Cochrane Library, and EMBASE databases were searched independently by two investigators to retrieve relevant studies published to March 21, 2015. The strength of the association was calculated with the odds ratio (OR) and 95% confidence interval (CI). All statistical tests were used by the RevMan 5.1 software (Nordic Cochrane Center, Copenhagen, Denmark). RESULTS: We observed a statistically significant association between rs2736109 polymorphism and breast cancer risk (OR = 1.13; 95% CI: 1.00-1.28; P = 0.04). In addition, rs2736109 polymorphism was associated with breast cancer risk in Caucasian population (OR = 1.18; 95% CI: 1.00-1.38; P = 0.04). We also found rs2853669 and rs2736098 polymorphisms were significantly associated with breast cancer risk (OR = 0.76; 95% CI: 0.63-0.90; P = 0.002 and OR = 0.79; 95% CI: 0.72-0.87; P < 0.00001), respectively. Furthermore, rs10069690 polymorphism was showed to be associated with breast cancer risk (OR = 1.16; 95% CI: 1.11-1.22; P < 0.00001). In the subgroup analysis, this polymorphism might be associated with estrogen receptor-negative breast cancer risk (OR = 1.16; 95% CI: 1.12-1.21; P < 0.00001) and breast cancer risk in Caucasian population (OR = 1.18; 95% CI: 1.14-1.23; P < 0.00001). One single nucleotide polymorphism, rs2735940, was not significantly associated with breast cancer risk (OR = 0.85; 95% CI: 0.66-1.11; P = 0.24). CONCLUSION: This meta-analysis suggested that TERT rs2736109, rs2853669, rs2736098, and rs10069690 polymorphisms were associated with increased risk of developing breast cancer.

[The surgical timing and effects for vitreous hemorrhage caused by ocular blunt trauma].

OBJECTIVE: To investigate the surgical timing and effects for vitreous hemorrhage caused by blunt ocular trauma. METHOD: 116 eyes of vitreous hemorrhage caused by ocular blunt trauma were divided into two groups, non-vitrectomy group (46 eyes) and vitrectomy group (70 eyes). The treating results and follow-up results were compared. RESULTS: 50 of 70 eyes (71.4%) in vitrectomy group and 10 of 46 eyes (21.7%) in non-vitrectomy group achieved a visual acuity of 0.1 or better over a follow-up period of 1 month, which indicated a significant difference between two groups. In the non-vitrectomy group, visual acuity of 10 eyes were better than 0.1, 7 eyes (70.0%) of them improved within 2 weeks of injury. In surgery group, 27.1% underwent only vitrectomy and 70.9% needed combining with other manipulations. In vitrectomy group the retina detachment was found in 3 eyes (4.3%) post-operatively and were cured by second operation. In non-vitrectomy group, the retinal detachment was found in 14 eyes (30.4%) during the follow-up period, and 8 eyes (72.7%) of 11 eyes received operation were cured. CONCLUSION: Early vitreous surgery can improve curative effect for vitreous hemorrhage caused by blunt ocular trauma when no improvement was observed after applied drugs 2 - 3 weeks.