Rapid exploration with multi-rotors: A frontier selection method for high speed flight

Exploring and mapping previously unknown environments while avoiding collisions with obstacles is a fundamental task for autonomous robots. In scenarios where this needs to be done rapidly, multi-rotors are a good choice for the task, as they can cover ground at potentially very high velocities. Flying at high velocities, however, implies the ability to rapidly plan trajectories and to react to new information quickly. In this paper, we propose an extension to classical frontier -based exploration that facilitates exploration at high speeds. The extension consists of a reactive mode in which the multi-rotor rapidly selects a goal frontier from its field of view. The goal frontier is selected in a way that minimizes the change in velocity necessary to reach it. While this approach can increase the total path length, it significantly reduces the exploration time, since the multi-rotor can fly at consistently higher speeds

Analysis of Sequence Variation and Risk Association of Human Papillomavirus 52 Variants Circulating in Korea

<div><p>Introduction</p><p>Human papillomavirus (HPV) 52 is a carcinogenic, high-risk genotype frequently detected in cervical cancer cases from East Asia, including Korea.</p><p>Materials and Methods</p><p>Sequences of HPV52 detected in 91 cervical samples collected from women attending Seoul St. Mary’s Hospital were analyzed. HPV52 genomic sequences were obtained by polymerase chain reaction (PCR)-based sequencing and analyzed using Seq-Scape software, and phylogenetic trees were constructed using MEGA6 software.</p><p>Results</p><p>Of the 91 cervical samples, 40 were normal, 22 were low-grade lesions, 21 were high-grade lesions and 7 were squamous cell carcinomas. Four HPV52 variant lineages (A, B, C and D) were identified. Lineage B was the most frequently detected lineage, followed by lineage C. By analyzing the two most frequently detected lineages (B and C), we found that distinct variations existed in each lineage. We also found that a lineage B-specific mutation K93R (A379G) was associated with an increased risk of cervical neoplasia.</p><p>Conclusions</p><p>To our knowledge, we are the first to reveal the predominance of the HPV52 lineages, B and C, in Korea. We also found these lineages harbored distinct genetic alterations that may affect oncogenicity. Our findings increase our understanding on the heterogeneity of HPV52 variants, and may be useful for the development of new diagnostic assays and therapeutic vaccines.</p></div

HPV52 variant lineage distribution of study samples.

<p>(A) Lineages A (sublineages: A1 and A2), B (sublineage: B2), C (sublineage: C2) and D were detected. (B) A phylogenetic tree was constructed from 57 HPV52 variants using concatenated L1, LCR, E6 and E7. A maximum-likelihood tree was constructed using the program, MEGA6. Bootstrap values of key nodes generated by 1,000 resamplings are shown. The length of the scale bar represents 0.005 substitutions per nucleotide position. To root the tree, HPV67 prototype sequences (NCBI accession no. NC_004710) were set as outgroup. The GenBank accession no. of study samples are KY077824-KY077901.</p