Practical Distributed Control for VTOL UAVs to Pass a Tunnel

Unmanned Aerial Vehicles (UAVs) are now becoming increasingly accessible to amateur and commercial users alike. An air traffic management (ATM) system is needed to help ensure that this newest entrant into the skies does not collide with others. In an ATM, airspace can be composed of airways, intersections and nodes. In this paper, for simplicity, distributed coordinating the motions of Vertical TakeOff and Landing (VTOL) UAVs to pass an airway is focused. This is formulated as a tunnel passing problem, which includes passing a tunnel, inter-agent collision avoidance and keeping within the tunnel. Lyapunov-like functions are designed elaborately, and formal analysis based on invariant set theorem is made to show that all UAVs can pass the tunnel without getting trapped, avoid collision and keep within the tunnel. What is more, by the proposed distributed control, a VTOL UAV can keep away from another VTOL UAV or return back to the tunnel as soon as possible, once it enters into the safety area of another or has a collision with the tunnel during it is passing the tunnel. Simulations and experiments are carried out to show the effectiveness of the proposed method and the comparison with other methods

Extensive tRNA gene changes in synthetic Brassica napus

Allopolyploidization, where two species come together to form a new species, plays a major role in speciation and genome evolution. Transfer RNAs (abbreviated tRNA) are typically 73-94 nucleotides in length, and are indispensable in protein synthesis, transferring amino acids to the cell protein synthesis machinery (ribosome). To date, the regularity and function of tRNA gene sequence variation during the process of allopolyploidization have not been well understood. In this study, the inter-tRNA gene corresponding to tRNA amplification polymorphism method was used to detect changes in tRNA gene sequences in the progeny of interspecific hybrids between Brassica rapa and B. oleracea, mimicking the original B. napus (canola) species formation event. Cluster analysis showed that tRNA gene variation during allopolyploidization did not appear to have a genotypic basis. Significant variation occurred in the early generations of synthetic B. napus (F and F generations), but fewer alterations were observed in the later generation (F). The variation-prone tRNA genes tended to be located in AT-rich regions. BlastN analysis of novel tRNA gene variants against a Brassica genome sequence database showed that the variation of these tRNA-gene-associated sequences in allopolyploidization might result in variation of gene structure and function, e.g., metabolic process and transport

Regularities in simple sequence repeat variations induced by a cross of resynthesized Brassica napus and natural Brassica napus

Interspecific hybridization can induce extensive variation in genome sequences, including simple sequence repeat (SSR) regions. To determine the characteristics of SSR variation induced by interspecific hybridization and the possible effect of SSR variation on gene function, we constructed a Brassica napus doubled-haploid (DH) population from a cross between natural B. napus and resynthesized B. napus (B. oleracea × B. rapa) and identified, located, sequenced and functionally annotated SSR variants.The results showed that novel SSR variants were generated in the F generation and maintained in the introgressed DH population. Elimination of sequences carrying SSRs also occurred in the F hybrids, with three times as many sequences lost in the introgressed DH population compared to in the F hybrids, probably due to non-homologous recombination. The degree of SSR variation observed depended primarily on the number of SSR repeats and secondarily on the nucleotide composition of the SSR motifs.In the introgressed DH population, many genes containing SSRs exhibited frameshift mutations (62.5%) due to the expansion or contraction of the SSR motifs following deletion deletion (25%) or insertion (12.5%) mutations.Most genes harboring SSR variants were associated with vital metabolic processes, such as protein or DNA metabolic processes. The SSR variation induced by interspecific hybridization reflects an intrinsic property of species adaptability post-hybridization through variation. This study is beneficial to understanding the origin of SSRs and the effects of SSR mutation on polyploid genomes

NBS-Encoding Genes in Brassica napus Evolved Rapidly After Allopolyploidization and Co-localize With Known Disease Resistance Loci

Genes containing nucleotide-binding sites (NBS) play an important role in pathogen resistance in plants. However, the evolutionary fate of NBS-encoding genes after formation of allotetraploid Brassica napus (AnAnCnCn, 2n = 38) is still unknown. We performed a genome-wide comparison of putatively functional NBS-encoding genes in B. napus and its progenitor species Brassica rapa (ArAr, 2n = 20) and Brassica oleracea (CoCo, 2n = 18), identifying 464, 202, and 146 putatively functional NBS-encoding genes respectively, with genes unevenly distributed in several clusters. The An-subgenome of B. napus possessed similar numbers of NBS-encoding genes (191 genes) to the Ar genome of B. rapa (202 genes) and similar clustering patterns. However, the Cn genome of B. napus had many more genes (273) than the B. oleracea Co genome (146), with different clustering trends. Only 97 NBS-encoding genes (66.4%) in B. oleracea were homologous with NBS-encoding genes in B. napus, while 176 NBS-encoding genes (87.1%) were homologous between B. rapa and B. napus. These results suggest a greater diversification of NBS-encoding genes in the C genome may have occurred after formation of B. napus. Although most NBS-encoding genes in B. napus appeared to derive from the progenitors, the birth and death of several NBS-encoding genes was also putatively mediated by non-homologous recombination. The Ka/Ks values of most homologous pairs between B. napus and the progenitor species were less than 1, suggesting purifying selection during B. napus evolution. The majority of NBS-encoding genes (60% in all species) showed higher expression levels in root tissue (out of root, leaf, stem, seed and flower tissue types). Comparative analysis of NBS-encoding genes with mapped resistance QTL against three major diseases of B. napus (blackleg, clubroot and Sclerotinia stem rot) found 204 NBS-encoding genes in B. napus located within 71 resistance QTL intervals. The majority of NBS-encoding genes were co-located with resistance QTLs against a single disease, while 47 genes were co-located with QTLs against two diseases and 3 genes were co-located with QTLs against all three. Our results revealed significant variation as well as interesting evolutionary trajectories of NBS-encoding genes in the different Brassica subgenomes, while co-localization of NBS-encoding genes and resistance QTL may facilitate resistance breeding in oilseed rape

Horizontal gene transfer in plants

Horizontal gene transfer (HGT) describes the transmission of genetic material across species boundaries. HGT often occurs in microbic and eukaryotic genomes. However, the pathways by which HGTs occur in multicellular eukaryotes, especially in plants, are not well understood. We systematically summarized more than ten possible pathways for HGT. The intimate contact which frequently occurs in parasitism, symbiosis, pathogen, epiphyte, entophyte, and grafting interactions could promote HGTs between two species. Besides these direct transfer methods, genes can be exchanged with a vector as a bridge: possible vectors include pollen, fungi, bacteria, viruses, viroids, plasmids, transposons, and insects. HGT, especially when involving horizontal transfer of transposable elements, is recognized as a significant force propelling genomic variation and biological innovation, playing an important functional and evolutionary role in both eukaryotic and prokaryotic genomes. We proposed possible mechanisms by which HGTs can occur, which is useful in understanding the genetic information exchange among distant species or distant cellular components

Postoperative high-density lipoprotein cholesterol level: an independent prognostic factor for gastric cancer

ObjectiveThe relationship between serum lipids and prognosis of gastric cancer has not been confirmed. Our purpose in the study was to investigate the associations between preoperative and postoperative serum lipids level and prognosis in patients with gastric cancer.MethodsA retrospective study was performed on 431 patients who received radical (R0) gastrectomy from 2011 to 2013. Preoperative and postoperative serum lipids level were recorded. Clinical-pathological characteristics, oncologic outcomes, disease-free survival (DFS) and overall survival (OS) were collected. The prognostic significance was determined by Kaplan-Meier analysis and Cox proportional hazards regression model.ResultsThere was no significant difference in DFS and OS according to preoperative serum lipids level. Regarding postoperative serum lipids level, compared to normal high-density lipoprotein cholesterol (HDL-C), low postoperative HDL-C level indicated a shorter OS (hazard ratio: 1.76, 99% confidence interval: 1.31–2.38; P=0.000) and a shorter DFS (hazard ratio: 2.06, 99% confidence interval: 1.55–2.73; P=0.000). However, other postoperative serum lipid molecules were not associated with DFS and OS.ConclusionPostoperative HDL-C might be an independent prognostic factor of gastric cancer

The Lunar Lander Neutron and Dosimetry (LND) Experiment on Chang'E 4

Chang'E 4 is the first mission to the far side of the Moon and consists of a lander, a rover, and a relay spacecraft. Lander and rover were launched at 18:23 UTC on December 7, 2018 and landed in the von K\'arm\'an crater at 02:26 UTC on January 3, 2019. Here we describe the Lunar Lander Neutron \& Dosimetry experiment (LND) which is part of the Chang'E 4 Lander scientific payload. Its chief scientific goal is to obtain first active dosimetric measurements on the surface of the Moon. LND also provides observations of fast neutrons which are a result of the interaction of high-energy particle radiation with the lunar regolith and of their thermalized counterpart, thermal neutrons, which are a sensitive indicator of subsurface water content.Comment: 38 pages, submitted to Space Science Review

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701