In this paper, a two-hop decode-and-forward (DF) multiple-input multiple-output (MIMO) relay system is investigated, where the relay node harvests the radio frequency energy transmitted by the source node and uses the harvested energy to forward information from source to destination. We consider both the time switching (TS) and power splitting (PS)-based protocols between wireless information and energy transfer. For each protocol, we study the optimal source and relay covariance matrices to maximize the source-destination mutual information (MI), under the source energy constraint and the harvested energy constraint at the relay node. For the TS protocol, the peak transmission power constraints are also considered at the source and relay nodes. The numerical results are presented to demonstrate the effectiveness of the proposed methods. It is shown that the proposed DF relay system achieves a higher MI than that of the amplify-and-forward relay system. Moreover, the PS-based protocol achieves a higher system MI than the TS-based protocol, but at a higher computational complexity. INDEX TERMS Decode-and-forward, energy harvesting, MIMO relay, power splitting, time switching. I. INTRODUCTION A. BACKGROUND VOLUME 7, 2019

We conducted this meta-analysis to explore the prognostic value of outpatient (or office) hysteroscopy (OH) preceding in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles in women who had experienced repeated implantation failure (RIF), particularly in regard to the conflicting evidence reported by previous studies. Two reviewers independently searched Pubmed, MEDLINE, Web of Science, Cochrane Library and Embase to identify all publications of clinical trials of hysteroscopy with or without endometrial biopsy in RIF patients. The primary outcome measures were clinical pregnancy rate (CPR) and live birth rate (LBR). Pooled relative ratios (RRs) with 95% confidence intervals (CIs) were calculated. Publication bias was detected using funnel plots and Egger's regression tests. Six eligible studies comprising 4143 patients were included. The CPR and LBR were both significantly higher in RIF patients with OH than RIF patients without OH (CPR: RR 1.34, 95% CI 1.14-1.57, P < 0.05; LBR: RR 1.29, 95% CI 1.03-1.62, P < 0.05). Subgroup analysis revealed a significant association between OH and CPR in Asia (CPR: RR 1.49, 95% CI 1.31-1.69; P < 0.05) rather than in Europe (CPR: RR 1.08, 95% CI 0.93-1.26; P = 0.291). However, there was no evidence of a significant difference in either CPR or LBR between the normal and abnormal OH groups (CPR: RR 0.92, 95% CI 0.83-1.02, P = 0.12; LBR: RR 0.76, 95% CI 0.37-1.56, P = 0.450). Hysteroscopy may potentially improve pregnancy outcomes in patients with RIP.

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ObjectiveThis study aimed to examine the prognostic value of overexpressed p16INK4a in vulvar cancer. Although the tumor suppressor p16INK4a has been shown to be of prognostic value in a wide variety of cancers and precancerous lesions, its role in the vulvar cancer is still unclear.MethodsAll publications in English language on the association between p16INK4a and clinicopathological features of vulvar cancer were searched from Pubmed, Embase, and Web of Science, and those in Chinese language were identified manually and online from the China National Knowledge Infrastructure. Strict inclusion and exclusion criteria were followed. Odds ratios(ORs) or risk ratios(RRs) with 95% confidence intervals(CIs) were pooled to assess the strength of association. Publication bias was estimated using funnel plots and the Egger’s regression test.ResultsA total of 17 studies with 2309 patients were included. The p16INK4a overexpression was found to correlate significantly with the lower International Federation of Gynecology and Obstetrics stage(I+II vs III+IV; OR = 0.60,95%CI:0.41–0.86,P = 0.006),negative lymph node metastasis(negative vs positive; OR = 0.61,95%CI:0.39–0.95,P = 0.029),patient’s age<55(OR = 0.54,95%CI:0.31–0.96,P = 0.034),human papillomavirus–positive status(OR = 0.01,95%CI:0.00–0.11,P<0.001),and higher overall survival(RR = 0.53,95%CI = 0.35–0.80,P = 0.003).ConclusionThe p16INK4a might be associated with a higher survival and indicates better prognosis of vulvar cancer.