Template-Guided Hierarchical Multi-View Registration Framework of Unordered Bridge Terrestrial Laser Scanning Data.

The registration of bridge point cloud data (PCD) is an important preprocessing step for tasks such as bridge modeling, deformation detection, and bridge health monitoring. However, most existing research on bridge PCD registration only focused on pairwise registration, and payed insufficient attention to multi-view registration. In addition, to recover the overlaps of unordered multiple scans and obtain the merging order, extensive pairwise matching and the creation of a fully connected graph of all scans are often required, resulting in low efficiency. To address these issues, this paper proposes a marker-free template-guided method to align multiple unordered bridge PCD to a global coordinate system. Firstly, by aligning each scan to a given registration template, the overlaps between all the scans are recovered. Secondly, a fully connected graph is created based on the overlaps and scanning locations, and then a graph-partition algorithm is utilized to construct the scan-blocks. Then, the coarse-to-fine registration is performed within each scan-block, and the transformation matrix of coarse registration is obtained using an intelligent optimization algorithm. Finally, global block-to-block registration is performed to align all scans to a unified coordinate reference system. We tested our framework on different bridge point cloud datasets, including a suspension bridge and a continuous rigid frame bridge, to evaluate its accuracy. Experimental results demonstrate that our method has high accuracy.

High-throughput dual-colour precision imaging for brain-wide connectome with cytoarchitectonic landmarks at the cellular level.

The precise annotation and accurate identification of neural structures are prerequisites for studying mammalian brain function. The orientation of neurons and neural circuits is usually determined by mapping brain images to coarse axial-sampling planar reference atlases. However, individual differences at the cellular level likely lead to position errors and an inability to orient neural projections at single-cell resolution. Here, we present a high-throughput precision imaging method that can acquire a co-localized brain-wide data set of both fluorescent-labelled neurons and counterstained cell bodies at a voxel size of 0.32 × 0.32 × 2.0 µm in 3 days for a single mouse brain. We acquire mouse whole-brain imaging data sets of multiple types of neurons and projections with anatomical annotation at single-neuron resolution. The results show that the simultaneous acquisition of labelled neural structures and cytoarchitecture reference in the same brain greatly facilitates precise tracing of long-range projections and accurate locating of nuclei.

Assembling and disassembling Ag clusters on Si(111)-(7×7) by vertical atomic manipulation.

Atomic manipulation has been rarely used in the studies of complex structures and a low temperature requirement usually limits its application. Herein we have demonstrated a vertical manipulation technique to reproducibly and reversibly manipulating Ag atoms on an Si(111)-(7×7) surface by a scanning tunneling microscope tip at room temperature. Simple and complex Ag nanoclusters were assembled and disassembled with a precise control of single Ag atoms, which provided critical information on the size of these nanoclusters. The manipulation showed the growth processes of these Ag clusters and even partly unveiled their atomic structures. This technique can form a fundamental basis for further studies of the Ag/Si(111)-(7×7) system and for fabricating functional nanodevices in various metal-semiconductor systems.

Size-dependent superconducting state of individual nanosized Pb islands grown on Si(111) by tunneling spectroscopy.

By measuring the temperature-dependent tunneling spectroscopy of a set of flat-top Pb islands from 3.2 to 15 K, the limiting size of a nine-monolayer-thick Pb island with superconductivity above 3.2 K was determined to be ∼ 30 nm(2), in good agreement with the Anderson criterion. Further analysis indicates that the zero-temperature energy gap decreases significantly faster than the transition temperature when the Pb island size approaches this limit. This leads to a decrease of 2Δ(0)/k(B)T(C) from 4.5 to 3.3, thus showing that the Pb island superconductors undergo a change from strong to weak electron-phonon coupling.