21 research outputs found
Screening and evaluating of long noncoding RNAs in the puberty of goats
GO analysis of predicted targets of lncRNAs in trans. (XLS 1551 kb
The Impact of Eclipsing GNSS Satellites on the Precise Point Positioning
When satellites enter into the noon maneuver or the shadow crossing regimes, the actual attitudes will depart from their nominal values. If improper attitude models are used, the induced-errors due to the wind-up effect and satellite antenna PCO (Phase Center Offset) will deteriorate the positioning accuracy. Because different generations of satellites adopt different attitude control models, the influences on the positioning performances deserve further study. Consequently, the impact of three eclipsing strategies on the single-system and multi-GNSS (Global Navigation Satellite System) Precise Point Positioning (PPP) are analyzed. According to the results of the eclipsing monitor, 65 globally distributed MGEX (Multi-GNSS EXperiment) stations for 31-day period in July 2017 are selected to perform G/R/E/C/GR/GREC PPP in both static and kinematic modes. The results show that the influences of non-nominal attitudes are related to the magnitude of the PCO values, maximum yaw angle differences, the duration of maneuver, the value of the sun angle and the satellite geometric strength. For single-system, using modeled attitudes rather than the nominal ones will greatly improve the positioning accuracy of GLONASS-only and BDS-only PPP while slightly contributions to the GPS-only and GALILEO-only PPP. Deleting the eclipsing satellites may sometimes induce a longer convergence time and a worse solution due to the poor satellite geometry, especially for GLONASS kinematic PPP when stations are located in the low latitude and BDS kinematic PPP. When multi-GNSS data are available, especially four navigation systems, the accuracy improvements of using the modeled attitudes or deleting eclipsing satellites are non-significant
The Impact of Yaw Attitude of Eclipsing GPS/GALILEO Satellites on Kinematic PPP Solutions and Their Correction Models
When GPS/GALILEO satellite runs to the position where it is approximately collinear with the sun and the earth, it is difficult for the satellite to keep nominal attitude, so it will show abnormal yaw attitude for a period of time. Based on the precision orbit and clock correction products offered by different analysis centers, we design different attitude correction strategies for satellite that is in abnormal yaw attitude period, select 10-day measured data from 7 MGEX stations distributed globally, and analyze the influence of antenna phase center offset and phase wind-up of GPS/GALILEO satellite on residuals of observations and kinematic PPP positioning result in this paper. The research results show that when the satellite is in abnormal yaw attitude period, adopting nominal yaw attitude can have an impact up to 8 cm and 11 cm on the residuals of GPS/GALILEO satellite observations. GPS/GALILEO satellite is in model yaw attitude during the period and its positioning accuracy of kinematic PPP positioning results in three directions of E, N and U shows an increasing rate of 13.30%, 15.77% and 12.98%, respectively in comparison with that in nominal yaw attitude. Comparing with satellite deletion strategy, the accuracy of kinematic PPP positioning results in three directions of E, N and U when the satellite is in model yaw attitude shows an increasing rate of 5.399%, 4.430% and 5.992%, respectively
Numerical study of the radio-frequency biased accelerating system in ion thrusters
A 2D-3V implicit immersed-finite-element particle-in-cell (IFE-PIC) model is introduced to investigate the radio-frequency (RF) self-bias accelerating system applied in the RF ion thruster. A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates. The characteristics of the plasma plume, such as the ion density, the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes (600-1200 V) and frequencies (6-30 MHz). Furthermore, the performance of the thruster was also carefully studied. The simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time (>= 12 MHz) in our simulation cases. The performance of the system can be evidently improved by increasing the voltage amplitude and the frequency, and the losses of the particle and thrust are reduced correspondingly. The bulk region of the plasma beam downstream shows good quasi-neutrality, and the ions are dominant in the peripheral region when a well-focused state is achieved. The high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing, while it is expanded radially when increasing the frequency. Backstream electrons have been observed upstream, and this mainly occurs in the phase in which the electron cannot escape
RNA-seq analysis of lncRNA-controlled developmental gene expression during puberty in goat & rat
Abstract Background Puberty is a pivotal stage in female animal development, and marks the onset of reproductive capability. However, little is known about the function of lncRNAs (long noncoding RNAs) in puberty. Therefore, RNA-seq analysis were performed between goats and rats to clarify the roles of lncRNAs and mRNAs in the onset of puberty. Results In the present study, the length of lncRNAs, the length of the open reading frame and the exon count were compared between the two species. Furthermore, functional annotation analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis of lncRNAs target genes and differentially expressed mRNA demonstrated the significantly enriched terms, such as AMPK signaling pathway, oxytocin signaling pathway, insulin secretion as well as pheromone receptor activity, and some other signaling pathways which were involved in the regulation of female puberty. Moreover, our results of siRNA interference in vitro showed the candidate lncRNA XLOC_446331 may play a crucial role in regulating female puberty. Conclusion In conclusion, the RNA-seq analysis between goat and rat provide novel candidate regulators for genetic and molecular studies on female puberty
DNA Methylation Patterns in the Hypothalamus of Female Pubertal Goats.
Female pubertal development is tightly controlled by complex mechanisms, including neuroendocrine and epigenetic regulatory pathways. Specific gene expression patterns can be influenced by DNA methylation changes in the hypothalamus, which can in turn regulate timing of puberty onset. In order to understand the relationship between DNA methylation changes and gene expression patterns in the hypothalamus of pubertal goats, whole-genome bisulfite sequencing and RNA-sequencing analyses were carried out. There was a decline in DNA methylation levels in the hypothalamus during puberty and 268 differentially methylated regions (DMR) in the genome, with differential patterns in different gene regions. There were 1049 genes identified with distinct expression patterns. High levels of DNA methylation were detected in promoters, introns and 3'-untranslated regions (UTRs). Levels of methylation decreased gradually from promoters to 5'-UTRs and increased from 5'-UTRs to introns. Methylation density analysis demonstrated that methylation level variation was consistent with the density in the promoter, exon, intron, 5'-UTRs and 3'-UTRs. Analyses of CpG island (CGI) sites showed that the enriched gene contents were gene bodies, intergenic regions and introns, and these CGI sites were hypermethylated. Our study demonstrated that DNA methylation changes may influence gene expression profiles in the hypothalamus of goats during the onset of puberty, which may provide new insights into the mechanisms involved in pubertal onset