1,529 research outputs found
HCV Genotyping with Concurrent Profiling of Resistance-Associated Variants by NGS Analysis
Determination of viral characteristics including genotype (GT), subtype (ST) and resistance-associated variants (RAVs) profile is important in assigning direct-acting antivirals regimes in HCV patients. To help achieve the best clinical management of HCV patients, a routine diagnostic laboratory should aim at reporting accurate viral GT/ST and RAVs using a reliable diagnostic platform of choice. A laboratory study was conducted to evaluate performance characteristics of a new commercial next-generation sequencing (NGS)-based HCV genotyping assay in comparison to another widely used commercial line probe assay for HCV genotyping. Information on RAVs from deeply sequenced NS3, NS5A and NS5B regions in samples classified as HCV 1a and 1b was harnessed from the fully automated software. Perfect (100%) concordance at HCV genotype level was achieved in GT2 (N = 13), GT3 (N = 55) and GT5 (N = 7). NGS refined the ST assignment in GTs 1, 4 and 6, and resolved previously indeterminate GTs reported by line probe assay. NGS was found to have consistent intra- and inter-run reproducibility in terms of genotyping, subtyping and RAVs identification. Detection of infections with multiple HCV GTs or STs is feasible by NGS. Deep sequencing allows sensitive identification of RAVs in the GT 1a and 1b NS3, NS5A and NS5B regions, but the list of target RAVs is not exhaustive
Ensemble reweighting using Cryo-EM particles
Cryo-electron microscopy (cryo-EM) has recently become a premier method for
obtaining high-resolution structures of biological macromolecules. However, it
is limited to biomolecular samples with low conformational heterogeneity, where
all the conformations can be well-sampled at many projection angles. While
cryo-EM technically provides single-molecule data for heterogeneous molecules,
most existing reconstruction tools cannot extract the full distribution of
possible molecular configurations. To overcome these limitations, we build on a
prior Bayesian approach and develop an ensemble refinement framework that
estimates the ensemble density from a set of cryo-EM particles by reweighting a
prior ensemble of conformations, e.g., from molecular dynamics simulations or
structure prediction tools. Our work is a general approach to recovering the
equilibrium probability density of the biomolecule directly in conformational
space from single-molecule data. To validate the framework, we study the
extraction of state populations and free energies for a simple toy model and
from synthetic cryo-EM images of a simulated protein that explores multiple
folded and unfolded conformations
Deep Learning in Single-Cell Analysis
Single-cell technologies are revolutionizing the entire field of biology. The
large volumes of data generated by single-cell technologies are
high-dimensional, sparse, heterogeneous, and have complicated dependency
structures, making analyses using conventional machine learning approaches
challenging and impractical. In tackling these challenges, deep learning often
demonstrates superior performance compared to traditional machine learning
methods. In this work, we give a comprehensive survey on deep learning in
single-cell analysis. We first introduce background on single-cell technologies
and their development, as well as fundamental concepts of deep learning
including the most popular deep architectures. We present an overview of the
single-cell analytic pipeline pursued in research applications while noting
divergences due to data sources or specific applications. We then review seven
popular tasks spanning through different stages of the single-cell analysis
pipeline, including multimodal integration, imputation, clustering, spatial
domain identification, cell-type deconvolution, cell segmentation, and
cell-type annotation. Under each task, we describe the most recent developments
in classical and deep learning methods and discuss their advantages and
disadvantages. Deep learning tools and benchmark datasets are also summarized
for each task. Finally, we discuss the future directions and the most recent
challenges. This survey will serve as a reference for biologists and computer
scientists, encouraging collaborations.Comment: 77 pages, 11 figures, 15 tables, deep learning, single-cell analysi
FroDO: From Detections to 3D Objects
Object-oriented maps are important for scene understanding since they jointly
capture geometry and semantics, allow individual instantiation and meaningful
reasoning about objects. We introduce FroDO, a method for accurate 3D
reconstruction of object instances from RGB video that infers object location,
pose and shape in a coarse-to-fine manner. Key to FroDO is to embed object
shapes in a novel learnt space that allows seamless switching between sparse
point cloud and dense DeepSDF decoding. Given an input sequence of localized
RGB frames, FroDO first aggregates 2D detections to instantiate a
category-aware 3D bounding box per object. A shape code is regressed using an
encoder network before optimizing shape and pose further under the learnt shape
priors using sparse and dense shape representations. The optimization uses
multi-view geometric, photometric and silhouette losses. We evaluate on
real-world datasets, including Pix3D, Redwood-OS, and ScanNet, for single-view,
multi-view, and multi-object reconstruction.Comment: To be published in CVPR 2020. The first two authors contributed
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Airflow Dynamics of Coughing in Healthy Human Volunteers by Shadowgraph Imaging: An Aid to Aerosol Infection Control
Cough airflow dynamics have been previously studied using a variety of experimental methods. In this study, real-time, non-invasive shadowgraph imaging was applied to obtain additional analyses of cough airflows produced by healthy volunteers. Twenty healthy volunteers (10 women, mean age 32.2±12.9 years; 10 men, mean age 25.3±2.5 years) were asked to cough freely, then into their sleeves (as per current US CDC recommendations) in this study to analyze cough airflow dynamics. For the 10 females (cases 1–10), their maximum detectable cough propagation distances ranged from 0.16–0.55 m, with maximum derived velocities of 2.2–5.0 m/s, and their maximum detectable 2-D projected areas ranged from 0.010–0.11 m2, with maximum derived expansion rates of 0.15–0.55 m2/s. For the 10 males (cases 11–20), their maximum detectable cough propagation distances ranged from 0.31–0.64 m, with maximum derived velocities of 3.2–14 m/s, and their maximum detectable 2-D projected areas ranged from 0.04–0.14 m2, with maximum derived expansion rates of 0.25–1.4 m2/s
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