3D Question Answering

Visual Question Answering (VQA) has witnessed tremendous progress in recent years. However, most efforts only focus on the 2D image question answering tasks. In this paper, we present the first attempt at extending VQA to the 3D domain, which can facilitate artificial intelligence's perception of 3D real-world scenarios. Different from image based VQA, 3D Question Answering (3DQA) takes the color point cloud as input and requires both appearance and 3D geometry comprehension ability to answer the 3D-related questions. To this end, we propose a novel transformer-based 3DQA framework "3DQA-TR", which consists of two encoders for exploiting the appearance and geometry information, respectively. The multi-modal information of appearance, geometry, and the linguistic question can finally attend to each other via a 3D-Linguistic Bert to predict the target answers. To verify the effectiveness of our proposed 3DQA framework, we further develop the first 3DQA dataset "ScanQA", which builds on the ScanNet dataset and contains $\sim$6K questions, $\sim$30K answers for $806$ scenes. Extensive experiments on this dataset demonstrate the obvious superiority of our proposed 3DQA framework over existing VQA frameworks, and the effectiveness of our major designs. Our code and dataset will be made publicly available to facilitate the research in this direction.Comment: To Appear at IEEE Transactions on Visualization and Computer Graphics (TVCG) 202

The Accelerated Urbanization Process: A Threat to Soil Resources in Eastern China

The eastern coastal region of China has been experiencing rapid urbanization which has imposed great challenges on soil resources, characterized by soil sealing and fragmented soil landscapes. Taking Zhejiang Province—a fairly economically-developed and highly-urbanized region in eastern China—as a case study, a practical framework that integrates remote sensing, GIS, soil quality assessment and landscape analysis was employed to track and analyze the rapid urbanization process and spatiotemporal dynamics of soil sealing and landscape change from 1990 to 2010. Meanwhile, this paper qualitatively explored the regional inequality and characteristics in soil sealing intensity among cities of different geo-zones in Zhejiang Province. Results showed that total area of 6420 km2 had been sealed during the past two decades for the entire study area, which represents 6.2% of the provincial area. Among these sealed soils, 68.6% are fertile soils located in flat plains, such as Paddy soils. Soil landscapes became more fragmented and dispersed in distribution, more irregular and complex in shape, and less dominant and diverse in soil type, as evidenced by the constant change of various spatial landscape metrics. What is more, different geo-zones exhibited significant differences in dynamics of soil sealing intensity, soil composition and soil landscape patterns. The permanent loss of valuable soil resource and increasing fragmented soil landscape patterns concomitant with rapid urbanization processes may inevitably bring about potential threats to regional soil resources and food security

A novel complex A/C/G intergenotypic recombinant of hepatitis B virus isolated in southern China.

Hepatitis B virus (HBV) genotypes and subgenotypes may vary in geographical distribution and virological features. Previous investigations, including ours, showed that HBV genotypes B and C were respectively predominant in South and North China, while genotypes A and D were infrequently detected and genotype G was not found. In this study, a novel A/C/G intergenotype was identified in patients with chronic HBV infection in Guilin, a city in southern China. Initial phylogenetic analysis based on the S gene suggested the HBV recombinant to be genotype G. However, extended genotyping based on the entire HBV genome indicated it to be an A/C/G intergenotype with a closer relation to genotype C. Breakpoint analysis using the SIMPLOT program revealed that the recombinant had a recombination with a arrangement of genotypes A, G, A and C fragments. Compared with the HBV recombinants harboring one or two genotype G fragments found in Asian countries, this Guilin recombinant was highly similar to the Vietnam (98-99%) and Long An recombinants (96-99%), but had a relatively low similarity to the Thailand one (89%). Unlike those with the typical genotype G of HBV, the patients with the Guilin recombinant were seropositive for HBeAg. Moreover, a relatively high HBV DNA viral load (>2 × 10(6) IU/ml) was detected in the patients, and the analysis of viral replication capacity showed that the Guilin recombinant strains had a competent replication capacity similar to genotypes B and C strains. These findings can aid in not only the clarification of the phylogenetic origin of the HBV recombinants with the genotype G fragment found in Asian countries, but also the understanding of the virological properties of these complicated HBV recombinants

Bootscan analysis demonstrating the complex recombination among genotypes A, C and G in the Guilin recombinant.

<p>The isolate from the female patient (A) and the isolate from the male patient (B) were subjected to bootscan analysis over the complete genome using the SIMPLOT program with a 500 bp window size, 10 bp step size and 100 bootstrap replicates, using gap-stripped alignments and neighbor-joining analysis, and were compared with three representative HBV genotypes: A (GenBank accession no. AB126580), C (GenBank accession no. AB050018) and G (GenBank accession no. AB064310). Woolly monkey was a known out-group (GenBank accession no. AF046996). Analysis was stared from nt 2700.</p

Figure 1. Phylogenetic analysis of the 14 clones derived from the Guilin recombinant compared with reference strains.

<p>GenBank accession numbers and clone numbers are showed on each tree, and the genotype is indicated after every accession number. Bootstrap values are showed at each nodes, and only bootstrap values of >70% are indicated. Phylogenetic trees comparing the 14 clones with 34 reference strains representing genotypes A–H, were constructed based on the S gene (A), pre-S region (B) and whole genomes (C). And the phylogenetic tree was constructed by comparing the Guilin recombinant with the Vietnam, Thailand and Long An recombinants as well as HBV C subgenotype based on the whole genomes (D).</p

Nucleotide distances between the Guilin HBV recombinant and other reference genotype strains^*.

<p>The reference genotype strains used in the table are the same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084005#pone-0084005-g001" target="_blank">Figure 1C</a>.</p