Automotive antennas are gaining importance due to their increasingly important role for autonomous driving with the development of the Internet of Vehicles. However, over‐the‐air testing on ...automotive antennas is difficult owing to its large volume and complex body structure. Plane wave generators can approximate uniform plane waves in the near field of the device under test, which can greatly reduce the measurement distance and thereby decreasing the cost compared with direct far‐field solutions. This letter designs three plane wave generators for three quiet zone sizes selected according to the vehicle structure at 5.9 GHz, achieving quiet zone sizes of 1.45 m ×0.23$\times 0.23$ m, 2.9m ×0.56$\times 0.56$ m, and 3.9 m ×1.27$\times 1.27$ m, respectively. Within the three quiet zones, amplitude deviations of 0.82, 0.34, and 0.34 dB and phase deviations of 9.4∘${9.4^\circ }$, 6.72∘${6.72^\circ }$ and 1.42∘${1.42^\circ }$ are realized, respectively, according to the numerical simulations. Uncertainty analysis is further implemented to investigate the robustness of the designed PWGs proposed in this letter.
This letter designs three plane wave generators for three quiet zone sizes selected according to the vehicle structure at sub‐6 GHz, achieving amplitude deviations of 0.82, 0.34, and 0.34 dB and phase deviations of 9.4∘$9.4^{\circ }$, 6.72∘$6.72^{\circ }$, and 1.42∘$1.42^{\circ }$, respectively, according to the numerical simulations. Uncertainty analysis is further implemented to investigate the robustness of the designed PWGs proposed in this letter.
Women with polycystic ovary syndrome are prone to develop gestational diabetes mellitus, a disease which may have significant impact on the postpartum health of both mother and infant. We performed a ...retrospective cohort study to develop and test a model that could predict gestational diabetes mellitus in the first trimester in women with polycystic ovary syndrome. Our study included 434 pregnant women who were referred to the obstetrics department between December 2017 and March 2020 with a diagnosis of polycystic ovary syndrome. Of these women, 104 were diagnosed with gestational diabetes mellitus in the second trimester. Univariate analysis revealed that in the first trimester, Hemoglobin A1c (HbA1C), age, total cholesterol(TC), low-density lipoprotein cholesterol (LDL-C), SBP (systolic blood pressure), family history, body mass index (BMI), and testosterone were predictive factors of gestational diabetes mellitus (P < 0.05). Logistic regression revealed that TC, age, HbA1C, BMI and family history were independent risk factors for gestational diabetes mellitus. The area under the ROC curve of the gestational diabetes mellitus risk prediction model was 0.937 in this retrospective analysis, demonstrating a great discriminatory ability. The sensitivity and specificity of the prediction model were 0.833 and 0.923, respectively. The Hosmer-Lemeshow test also showed that the model was well calibrated.
Tanshinone IIA (Tan IIA) is a natural product that has been identified to have anti-proliferative properties against cervical cancer. The study was designed to investigate the anti-tumor effects of ...Tan IIA at different concentrations on the proliferation and apoptosis of human cervical carcinoma C4-1 cells. Human cervical carcinoma C4-1 cells were treated with different doses of Tan IIA, and MTT assay was performed to determine effects on cell viability. Flow cytometry was used to detect apoptosis and Western blot analysis was carried out to determine alterations in the expression of key proteins. Tan IIA treatment (0.5, 1.0, 2.0, and 5.0 mg/mL) significantly inhibited the growth of C4-1 cells in a time- and dose-dependent manner. Significant differences were observed in the growth inhibition rate between Tan IIA group and the control group (0.5-1.0 mg/L Group: p < 0.05; 2.0-5.0 mg/L Group: p < 0.01). Flow cytometry showed that C4-1 cells became apoptotic after treatment with Tan IIA. In the control group, the apoptosis rate of C4-1 cells was 2.56 ± 0.21% whilst in the Tan IIA-treated groups, different concentrations markedly increased the rate of apoptosis (1.0 mg/L group, 7.9 ± 0.43% p < 0.05; 2.0 g/L group, 10.2 ± 0.42%; 5.0 mg/L, 20.44 ± 1.24% p < 0.01; except 0.5 mg/L group, 5.8 ± 0.32% p > 0.05). Western blot assays indicated that the Tan IIA decreased Bcl-2, HPV 16 E6 and E7 protein levels, but elevated Bax and cleaved-Caspase-3 expression in cells. Tan IIA may inhibit the proliferation and induce the apoptosis of C4-1 cells in a concentration-dependent manner.
•Firms registered in governors’ hometowns may have more investment expenditures.•Governances’ social identity affects corporate investment.•Chinese-listed firm data reveals the factors influencing ...hometown favoritism.•Governors prioritize their administrative duties over hometown favoritism.•Increased hometown firm investments lead to investment inefficiency.
We investigate the effects of governors’ hometown favoritism on the corporate investments of Chinese listed firms. Exploiting the exogenous distribution of governors’ tenure in a difference-in-differences research design, we find that firms in an incumbent governor's hometown make higher investments by 10.26%. This favoritism effect is more pronounced when any of the following are true about a governor's hometown: has a culture background of high collectivism, has strong clan culture, uses a minor local dialect, or if the governor has strong clan ties. Additional analyses rule out the social ties generated through living or working experiences as an alternative explanation. Neither political connections nor self-interest incentives explain the effects of hometown favoritism. Furthermore, the increased investments are overall detrimental for investment efficiency.Our study contributes to the literature by applying the social identity theory in corporate research and provides novel evidence on how politicians’ social identity affects corporate investment.
Species authentication of meat product origins has become an important subject for ensuring the health of consumers. Based on the cytochrome b gene, we developed a PCR-based assay kit for ...identification of Chinese mink tissues from 10 animal species in meat products, and to evaluate its quality indices including specificity, stability, sensitivity, and repeatability. Kits were made up of DNA extraction and PCR amplification systems based on species-specific, and universal primers. The reference meat mixtures and commercial samples were extracted by the kit and PCR technique was performed to identify the species of mink authenticity. The kit was effective after 20 repeated freeze-thaw cycles and it could be stored at -20 °C for 1 year. The sensitivity showed that a concentration as low as 0.1 ng/μL still can amplify the target band. The specificity test confirmed that the kit was 100% specific. The kit proved to be effective, stable, and reliable for extraction of efficient contents of the genomic DNA and routine analysis of Chinese mink source composition from meat products.
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•Spontaneous Raman spectroscopy can be used to measure the purity of chiral molecules.•The O–H stretching vibration band can be used to infer enantiomeric excess (ee value).•A rapid ...method for detecting the ee value of mandelic acid is proposed.
Chiral molecules play a very important role in biological systems, and more and more chiral drugs are used in the treatment of diseases. Mandelic acid (MA) is an important chiral starting substance or the key intermediate of some chiral drugs, and the rapid detection of its chiral purity is very important in the synthesis, separation and detection of drugs. In this study, we developed a method for rapid determination of chiral purity of MA by Raman spectroscopy, and measured a series of Raman spectra of different chiral MA. Through the analysis, it is found that the OH stretching vibration peak can be used to identify the components of chiral molecules, and the enantiomeric excess (ee value) obtained is in good agreement with the real value, and the error is about 5%. The experimental detection speed is fast and the efficiency is high. Our work firstly provides a new idea for the purity detection of chiral molecules by the original Raman spectrum.
PurposeThe reviews submitted by users are the foundation of user-generated content (UGC) platforms. However, the rapid growth of users brings the problems of information overload and spotty content, ...which makes it necessary for UGC platforms to screen out reviews that are really helpful to users. The authors put forward in this paper the factors influencing review helpfulness voting from the perspective of review characteristics and reviewer characteristics.Design/methodology/approachThis study uses 8,953 reviews from 20 movies listed on Douban.com with variables focusing on review characteristics and reviewer characteristics that affect review helpfulness. To verify the six hypotheses proposed in the study, Stata 14 was used to perform tobit regression.FindingsFindings show that review helpfulness is significantly influenced by the length, valence, timeliness and deviation rating of the reviews. The results also underlie that a review submitted by a reviewer who has more followers and experience is more affected by review characteristics.Originality/valuePrevious literature has discussed the factors that affect the helpfulness of reviews; however, the authors have established a new model that explores more comprehensive review characteristics and the moderating effect reviewer characteristics have on helpfulness. In this empirical research, the authors selected a UGC community in China as the research object. The UGC community may encourage users to write more helpful reviews by highlighting the characteristics of users. Users in return can use this to establish his/her image in the community. Future research can explore more variables related to users.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/OIR-05-2020-0186.
Objective
To identify both the trends in placenta accreta spectrum (PAS) disorders in the context of the universal two‐child policy in China and risk factors for hysterectomy.
Methods
The present ...retrospective analysis included confirmed PAS disorders during cesarean delivery at a tertiary hospital in Changsha, Hunan, China, from January 1, 2007, to December 31, 2016. Multivariable logistic regression was used to estimate the risk of hysterectomy.
Results
During the 10‐year study period, the overall incidence of cesarean delivery was 51.6% (13 530/26 214) and that of PAS disorders was 1.2% (302/26 214). The PAS rate increased from 0.1% (5/4617) in 2007–2008 to 2.1% (133/6351) in 2015–2016, alongside a rise in elective repeat cesarean delivery from 5.0% (106/2124) to 38.4% (1385/3603). Previous cesarean delivery greatly increased the likelihood of PAS disorders (odds ratio OR 97.4; P<0.001). Invasive depth (OR 92.0; P<0.001), inter‐cesarean interval less than 36 months (OR 7.0; P=0.002), rural residence (OR 5.3; P=0.018), and advanced maternal age (OR 3.0; P=0.045) were independent risk factors for hysterectomy among women with PAS disorders.
Conclusion
The increasing incidence of elective repeat cesarean delivery combined with a high overall rate of cesarean delivery implies a high prevalence of PAS disorders within the context of the universal two‐child policy in China. The main predictor of hysterectomy was invasive depth.
Increasing elective repeat cesarean delivery and placenta accreta spectrum disorder rates were observed at a tertiary hospital in China. Hysterectomy was associated with invasive depth.
With the fast development of communication techniques, over-the-air testing has developed into the main testing method for current communication systems due to its advantages including no cable ...connection, high measurement efficiency, and independence from environment. OTA testing has become almost the only solution for 5G system testing especially after the popularity of 5G massive multiple-input-multiple-output. In this paper, we summarize the three main methods of OTA testing including the reverberation chamber-based method, the radiation two-step method, and the multiprobe anechoic chamber- (MPAC-) based method, among which we focus on the MPAC method systematically. In the MPAC method, there are two main channel synthesis techniques that have been heavily studied, namely, prefaded signal synthesis and plane wave synthesis. We summarize the current main research based on these two techniques including probe configurations, probe selection algorithms, and probe design based on the PFS technique and the design of plane wave generators based on PWS technique. The main comparisons are made for the performance of different probe selection algorithms and the performance of different plane wave generators as well as the latest advances.
To carry out preimplantation genetic testing (PGT) for a Chinese pedigree affected with Rett syndrome (RTT).
A pedigree affected with RTT who had presented at the First Hospital of Jilin University ...on June 4, 2021 was selected as the study subject. Variant of the MECP2 gene was analyzed by next generation sequencing (NGS) and Sanger sequencing. Direct sequencing was also used to determine the carrier status for the c.925C>T variant of the MECP2 gene in the blastocysts, and Sanger sequencing was used to validate the results. The MECP2 gene and 168 effective single nucleotide polymorphism (SNP) loci within 2 Mb ranges up- and downstream of the gene were used to construct a haplotype for analyzing the variant site in the embryos, and embryos without the variant were subjected to the analysis for chromosomal aneuploidies.
PGT analysis revealed that five out of seven blastocysts did not harbor the pathogenic variant. The results of aneuploidy analysis indicated that two out of five blastocysts without the variant
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