Comparison of spontaneous fetal loss rates between women with singleton and twin pregnancies after mid-trimester amniocentesis - A historical cohort study.

OBJECTIVE: To assess and compare fetal loss rates before 28 weeks of singleton and twin pregnancies after mid-trimester amniocentesis. METHOD: This historic cohort study included 13 773 women with singletons and 426 women with twins undergoing mid-trimester amniocentesis from 1/2015 to 3/2017. Pregnancies resulting in termination or selective reduction before 28 weeks were excluded, as well as twin gestations undergoing single-puncture amniocentesis. Fetal loss rates were compared between singleton and twins taking into account maternal characteristics, amniocentesis procedure, and fetal chromosomal abnormalities. RESULTS: The rates of fetal chromosomal abnormalities were similar in singleton and twin gestations (1.13% vs 0.70%, P = .253). No difference was found in maternal or fetal characteristics, or amniocentesis procedure between the two groups. The fetal loss rate was significantly higher in twin compared with singleton pregnancies (1.91% vs 0.24%, P < .001, RR = 8.25 [95% CI: 4.51 to 15.09]). The fetal loss rate between monochorionic twins and dichorionic twins was similar (1.80% vs 1.78%, P = 1.000). CONCLUSIONS: Twin pregnancies have higher risk of fetal loss after mid-trimester amniocentesis, which cannot be explained by differences in rates of fetal chromosomal abnormalities, maternal characteristic, or amniocentesis technique.

Modeling and Analysis of Micro-Spacecraft Attitude Sensing with Gyrowheel.

This paper proposes two kinds of approaches of angular rate sensing for micro-spacecraft with a gyrowheel (GW), which can combine attitude sensing with attitude control into one single device to achieve a compact micro-spacecraft design. In this implementation, during the three-dimensional attitude control torques being produced, two-dimensional spacecraft angular rates can be sensed from the signals of the GW sensors, such as the currents of the torque coils, the tilt angles of the rotor, the motor rotation, etc. This paper focuses on the problems of the angular rate sensing with the GW at large tilt angles of the rotor. For this purpose, a novel real-time linearization approach based on Lyapunov's linearization theory is proposed, and a GW linearized measurement model at arbitrary tilt angles of the rotor is derived. Furthermore, by representing the two-dimensional rotor tilt angles and tilt control torques as complex quantities and separating the twice periodic terms about the motor spin speed, the linearized measurement model at smaller tilt angles of the rotor is given and simplified. According to the respective characteristics, the application schemes of the two measurement models are analyzed from the engineering perspective. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed strategy.

Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer.

A gyrowheel (GW) is a kind of electronic electric-mechanical servo system, which can be applied to a spacecraft attitude control system (ACS) as both an actuator and a sensor simultaneously. In order to solve the problem of two-dimensional spacecraft angular rate sensing as a GW outputting three-dimensional control torque, this paper proposed a method of an extended high gain observer (EHGO) with the derived GW mathematical model to implement the spacecraft angular rate estimation when the GW rotor is working at large angles. For this purpose, the GW dynamic equation is firstly derived with the second kind Lagrange method, and the relationship between the measurable and unmeasurable variables is built. Then, the EHGO is designed to estimate and calculate spacecraft angular rates with the GW, and the stability of the designed EHGO is proven by the Lyapunov function. Moreover, considering the engineering application, the effect of measurement noise in the tilt angle sensors on the estimation accuracy of the EHGO is analyzed. Finally, the numerical simulation is performed to illustrate the validity of the method proposed in this paper.

[A new teaching mode improves the effect of comprehensive experimental teaching of genetics].

To improve the research atmosphere in genetics experimental teaching and develop students' creativity in research, we carried out a reform in comprehensive experimental teaching which is one of important modules for genetics practice. In our new student-centered teaching mode, they chose research topics, performed experiments and took innovative approaches independently. With the open laboratory and technical platform in our experimental teaching center, students finished their experiments and were required to write a mini-research article. Comprehensive experimental teaching is a scientific research practice before they complete their thesis. Through this teaching practice, students' research skills in experimental design and operation, data analysis and results presentation, as well as their collaboration spirit and innovation consciousness are strengthened.

[Research progress on the cloning of Mendel's gene in pea (Pisum sativum L.) and its application in genetics teaching].

One hundred and fifty years ago, Gregor Mendel investigated the segregation of seven traits in pea (Pisum sativum) and established the law of segregation and the law of independent assortment in genetics. After the two laws of genetics were rediscovered in 1900, the seven traits have been extensively investigated in the fields of plant physiology and biochemistry as well as in the cell and molecular levels. Recently, with the development of molecular technology in genetics, four genes for seed shape (R), stem length (Le), cotyledon colour (I), and flower colour (A) have been cloned and sequenced; and another three genes for immature pod colour (Gp), fasciation (Fa) and pod form (V) have been located in the linkage groups, respectively. The identification and cloning of the four Mendel's genes will help deeply understand the basic concept of gene in many respects: like the diversity of gene function, the different origins for gene mutation in molecular level, and the molecular nature of a dominant gene or a recessive gene. In teaching of genetics, the introduction of most recent research advancements of cloning of Mendel's genes to the students and the interpretation of the Mendel's laws in molecular level will help students promote their learning interests in genetics and help students grasp the whole content from classical genetics to molecular genetics and the developmental direction of this subject.

[Effect of three-stage sequential method on interleukin-5 mRNA expression in the lung tissue of asthmatic model rat treated with steroid].

OBJECTIVE: To observe the effect of three-stage sequential method (TSSM) on interleukin-5 (IL-5) mRNA expression in the lung tissue of asthmatic rat model treated with steroid. METHODS: SD rats were randomly divided into 8 groups, the normal control group (GA), the model group (GB), the model with steroid intervention group (GC) and the 5 treated groups (GD - GH). Excepting those in the GA, all rats were established into the asthma model and rats in GC-GH were intervened by dexamethasone, with the dosage reduced by 0.1 mg/kg per week starting from the 3rd week and withdrawn completely till the 7th week. At the same time, rats in GD - GH were treated with TSSM, and the 1st, 2nd and 3rd recipe of TSSM, as well as pulmicort respules (as positive control) respectively. IL-5 mRNA expression in the lung tissue of rats was detected at different time points by in situ hybridization. RESULTS: Comparisons of GD with other groups in IL-5 mRNA expression showed: it was remarkably lowered than that in GB and GC at all time points (P < 0.01); compared to GH, the difference was insignificant at the end of the 2nd week, but significant at the end of the 7th and 9th week (P < 0.01); as for the difference between GD with GE, GF and GG, it showed very significant difference (P < 0.01) at all the time points besides that at the end of the 2nd week, it showed insignificance to GE (P > 0.05) and significance to GF (P < 0.05). The dynamic changes of IL-5 mRNA expression in GD during the steroid withdrawal period showed the lowering was more significantly at the end of the 7th and 9th week than that at the end of the 2nd week (P < 0.05, P < 0.01), but its levels were equal at the former two time points; its lowest level appeared at the end of the 9th week, which approaching the level in GA (P > 0.05). CONCLUSION: Three-stage sequential method could remarkably inhibit IL-5 mRNA expression in the lung tissue of asthmatic rats undergoing steroid treatment.

Development of a wide population of chromosome single-segment substitution lines in the genetic background of an elite cultivar of rice (Oryza sativa L.).

Naturally occurring allelic variations underlying complex traits are useful resources for the functional analysis of plant genes. To facilitate the genetic analysis of complex traits and the use of marker-assisted breeding in rice, we developed a wide population consisting of 217 chromosome single-segment substitution lines (SSSLs) using Oryza sativa L. 'Hua-Jing-Xian74' (HJX74), an elite Indica cultivar, as recipient, and 6 other accessions, including 2 Indica and 4 Japonica, as donors. Each SSSL contains a single substituted chromosome segment derived from 1 of the 6 donors in the genetic background of HJX74. The total size of the substituted segments in the SSSL population was 4695.0 cM, which was 3.1 times that of rice genome. To evaluate the potential application of these SSSLs for quantitative trait loci detection, phenotypic variations of the quantitative traits of days to heading and grain length in the population consisting of 210 SSSLs were observed under natural environmental conditions. The results demonstrated that there was a wide range of phenotypic variation in the traits in the SSSL population. These genetic materials will be powerful tools to dissect complex traits into a set of monogenic loci and to assign phenotypic values to different alleles at the locus of interest.

[Developing single segment substitution lines (SSSLs) in rice (Oryza sativa L.) using advanced backcrosses and MAS].

A novel population consisted of 86 single segment substitution lines (SSSLs) were developed from advanced backcrosses between the recipient, Huajingxian 74 and six donors by microsatellite marker-assisted selection (MAS). Fifty-two SSSLs were selected in BC3F2, and 34 others were selected in BC3F3. Every SSSL contains a single chromosome segment introgressed from one donor on the genetic background of Huajingxian 74. The substituted segments in SSSLs were distributed on 12 rice chromosomes. The estimated length of the substituted segments in SSSLs ranged from 1.5 cM to 56.3 cM with an average of 23.0 cM. Total of the substituted segments covered 57.1% of the rice genome.