134 research outputs found
Development of a new elastic path controller for the collaborative wheelchair assistant
Ph.DDOCTOR OF PHILOSOPH
Characterization of Small Interfering RNAs Derived from the Geminivirus/Betasatellite Complex Using Deep Sequencing
BACKGROUND: Small RNA (sRNA)-guided RNA silencing is a critical antiviral defense mechanism employed by a variety of eukaryotic organisms. Although the induction of RNA silencing by bipartite and monopartite begomoviruses has been described in plants, the nature of begomovirus/betasatellite complexes remains undefined. METHODOLOGY/PRINCIPAL FINDINGS: Solanum lycopersicum plant leaves systemically infected with Tomato yellow leaf curl China virus (TYLCCNV) alone or together with its associated betasatellite (TYLCCNB), and Nicotiana benthamiana plant leaves systemically infected with TYLCCNV alone, or together with TYLCCNB or with mutant TYLCCNB were harvested for RNA extraction; sRNA cDNA libraries were then constructed and submitted to Solexa-based deep sequencing. Both sense and anti-sense TYLCCNV and TYLCCNB-derived sRNAs (V-sRNAs and S-sRNAs) accumulated preferentially as 22 nucleotide species in infected S. lycopersicum and N. benthamiana plants. High resolution mapping of V-sRNAs and S-sRNAs revealed heterogeneous distribution of V-sRNA and S-sRNA sequences across the TYLCCNV and TYLCCNB genomes. In TYLCCNV-infected S. lycopersicum or N. benthamiana and TYLCCNV and βC1-mutant TYLCCNB co-infected N. benthamiana plants, the primary TYLCCNV targets were AV2 and the 5' terminus of AV1. In TYLCCNV and betasatellite-infected plants, the number of V-sRNAs targeting this region decreased and the production of V-sRNAs increased corresponding to the overlapping regions of AC2 and AC3, as well as the 3' terminal of AC1. βC1 is the primary determinant mediating symptom induction and also the primary silencing target of the TYLCCNB genome even in its mutated form. CONCLUSIONS/SIGNIFICANCE: We report the first high-resolution sRNA map for a monopartite begomovirus and its associated betasatellite using Solexa-based deep sequencing. Our results suggest that viral transcript might act as RDR substrates resulting in dsRNA and secondary siRNA production. In addition, the betasatellite affected the amount of V-sRNAs detected in S. lycopersicum and N. benthamiana plants
Amorphous photonic topological insulator
Photonic topological insulators (PTIs) exhibit robust photonic edge states
protected by band topology, similar to electronic edge states in topological
band insulators. Standard band theory does not apply to amorphous phases of
matter, which are formed by non-crystalline lattices with no long-range
positional order but only short-range order. Among other interesting
properties, amorphous media exhibit transitions between glassy and liquid
phases, accompanied by dramatic changes in short-range order. Here, we
experimentally investigate amorphous variants of a Chern-number-based PTI. By
tuning the disorder strength in the lattice, we demonstrate that photonic
topological edge states can persist into the amorphous regime, prior to the
glass-to-liquid transition. After the transition to a liquid-like lattice
configuration, the signatures of topological edge states disappear. This
interplay between topology and short-range order in amorphous lattices paves
the way for new classes of non-crystalline topological photonic materials.Comment: 13 pages, 4 figure
Observation of photonic antichiral edge states
Chiral edge states are a hallmark feature of two-dimensional topological
materials. Such states must propagate along the edges of the bulk either
clockwise or counterclockwise, and thus produce oppositely propagating edge
states along the two parallel edges of a strip sample. However, recent theories
have predicted a counterintuitive picture, where the two edge states at the two
parallel strip edges can propagate in the same direction; these anomalous
topological edge states are named as antichiral edge states. Here we report the
experimental observation of antichiral edge states in a gyromagnetic photonic
crystal. The crystal consists of gyromagnetic cylinders in a honeycomb lattice,
with the two triangular sublattices magnetically biased in opposite directions.
With microwave measurement, unique properties of antichiral edge states have
been observed directly, which include the titled dispersion, the chiral-like
robust propagation in samples with certain shapes, and the scattering into
backward bulk states at certain terminations. These results extend and
supplement the current understanding of chiral edge states
Assessment of codivergence of Mastreviruses with their plant hosts
Background: Viruses that have spent most of their evolutionary time associated with a single host lineage should have sequences that reflect codivergence of virus and host. Several examples for RNA viruses of host-virus tree congruence are being challenged. DNA viruses, such as mastreviruses, are more likely than RNA viruses to have maintained a record of host lineage association.Results: The full genomes of 28 isolates of Wheat dwarf virus (WDV), a member of the Mastrevirus genus, from different regions of China were sequenced. The analysis of these 28 entire genomes and 18 entire genome sequences of cereal mastreviruses from other countries support the designation of wheat, barley and oat mastrevirus isolates as separate species. They revealed that relative divergence times for the viruses WDV, Barley dwarf virus (BDV), Oat dwarf virus (ODV) and Maize streak virus (MSV) are proportional to divergence times of their hosts, suggesting codivergence. Considerable diversity among Chinese isolates was found and was concentrated in hot spots in the Rep A, SIR, LIR, and intron regions in WDV genomes. Two probable recombination events were detected in Chinese WDV isolates. Analysis including further Mastrevirus genomes concentrated on coding regions to avoid difficulties due to recombination and hyperdiversity. The analysis demonstrated congruence of trees in two branches of the genus, but not in the third. Assuming codivergence, an evolutionary rate of 10-8 substitutions per site per year was calculated. The low rate implies stronger constraints against change than are obtained by other methods of estimating the rate.Conclusion: We report tests of the hypothesis that mastreviruses have codiverged with their monocotyledonous hosts over 50 million years of evolution. The tests support the hypothesis for WDV, BDV and ODV, but not for MSV and other African streak viruses.Peer reviewedBiochemistry and Molecular Biolog
The prognostic value of multiparametric cardiac magnetic resonance in patients with systemic light chain amyloidosis
BackgroundLate gadolinium enhancement (LGE) is a classic imaging modality derived from cardiac magnetic resonance (CMR), which is commonly used to describe cardiac tissue characterization. T1 mapping with extracellular volume (ECV) and native T1 are novel quantitative parameters. The prognostic value of multiparametric CMR in patients with light chain (AL) amyloidosis remains to be thoroughly investigated.MethodsA total of 89 subjects with AL amyloidosis were enrolled from April 2016 to January 2021, and all of them underwent CMR on a 3.0 T scanner. The clinical outcome and therapeutic effect were observed. Cox regression was used to investigate the effect of multiple CMR parameters on outcomes in this population.ResultsLGE extent, native T1 and ECV correlated well with cardiac biomarkers. During a median follow-up of 40 months, 21 patients died. ECV (hazard ratio [HR]: 2.087 for per 10% increase, 95% confidence interval [CI]: 1.379-3.157, P < 0.001) and native T1 (HR: 2.443 for per 100 ms increase, 95% CI: 1.381-4.321, P=0.002) were independently predictive of mortality. A novel prognostic staging system based on median native T1 (1344 ms) and ECV (40%) was similar to Mayo 2004 Stage, and the 5-year estimated overall survival rates in Stage I, II, and III were 95%, 80%, and 53%, respectively. In patients with ECV > 40%, receiving autologous stem cell transplantation had higher cardiac and renal response rates than conventional chemotherapy.ConclusionBoth native T1 and ECV independently predict mortality in patients with AL amyloidosis. Receiving autologous stem cell transplantation is effective and significantly improves the clinical outcomes in patients with ECV > 40%
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Author Correction: A deep-learning pipeline for the diagnosis and discrimination of viral, non-viral and COVID-19 pneumonia from chest X-ray images.
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