4,187 research outputs found
Calculation of Critical Nucleation Rates by the Persistent Embryo Method: Application to Quasi Hard Sphere Models
We study crystal nucleation of the Weeks-Chandler-Andersen (WCA) model, using
the recently introduced Persistent Embryo Method (PEM). The method provides
detailed characterization of pre-critical, critical and post-critical nuclei,
as well as nucleation rates that compare favorably with those obtained using
other methods (umbrella sampling, forward flux sampling or seeding). We further
map our results to a hard sphere model allowing to compare with other existing
predictions. Implications for experiments are also discussed.Comment: 27 pages, 11 figure
Aggregating Long-term Sharp Features via Hybrid Transformers for Video Deblurring
Video deblurring methods, aiming at recovering consecutive sharp frames from
a given blurry video, usually assume that the input video suffers from
consecutively blurry frames. However, in real-world blurry videos taken by
modern imaging devices, sharp frames usually appear in the given video, thus
making temporal long-term sharp features available for facilitating the
restoration of a blurry frame. In this work, we propose a video deblurring
method that leverages both neighboring frames and present sharp frames using
hybrid Transformers for feature aggregation. Specifically, we first train a
blur-aware detector to distinguish between sharp and blurry frames. Then, a
window-based local Transformer is employed for exploiting features from
neighboring frames, where cross attention is beneficial for aggregating
features from neighboring frames without explicit spatial alignment. To
aggregate long-term sharp features from detected sharp frames, we utilize a
global Transformer with multi-scale matching capability. Moreover, our method
can easily be extended to event-driven video deblurring by incorporating an
event fusion module into the global Transformer. Extensive experiments on
benchmark datasets demonstrate that our proposed method outperforms
state-of-the-art video deblurring methods as well as event-driven video
deblurring methods in terms of quantitative metrics and visual quality. The
source code and trained models are available at
https://github.com/shangwei5/STGTN.Comment: 13 pages, 11 figures, and the code is available at
https://github.com/shangwei5/STGT
A Biomechanical Analysis of the Interlock Suture and a Modified Kessler-Loop Lock Flexor Tendon Suture
OBJECTIVE: In this work, we attempted to develop a modified single-knot Kessler-loop lock suture technique and compare the biomechanical properties associated with this single-knot suture technique with those associated with the conventional modified Kessler and interlock suture techniques. METHODS: In this experiment, a total of 18 porcine flexor digitorum profundus tendons were harvested and randomly divided into three groups. The tendons were transected and then repaired using three different techniques, including modified Kessler suture with peritendinous suture, interlock suture with peritendinous suture, and modified Kessler-loop lock suture with peritendinous suture. Times required for suturing were recorded and compared among groups. The groups were also compared with respect to 2-mm gap load, ultimate failure load, and gap at failure. RESULTS: For tendon repair, compared with the conventional modified Kessler suture technique, the interlock and modified Kessler-loop lock suture techniques resulted in significantly improved biomechanical properties. However, there were no significant differences between the interlock and modified Kessler-loop lock techniques with respect to biomechanical properties, gap at failure, and time required. CONCLUSIONS: The interlock and modified Kessler-loop lock techniques for flexor tendon sutures produce similar mechanical characteristics in vitro
Joint Video Multi-Frame Interpolation and Deblurring under Unknown Exposure Time
Natural videos captured by consumer cameras often suffer from low framerate
and motion blur due to the combination of dynamic scene complexity, lens and
sensor imperfection, and less than ideal exposure setting. As a result,
computational methods that jointly perform video frame interpolation and
deblurring begin to emerge with the unrealistic assumption that the exposure
time is known and fixed. In this work, we aim ambitiously for a more realistic
and challenging task - joint video multi-frame interpolation and deblurring
under unknown exposure time. Toward this goal, we first adopt a variant of
supervised contrastive learning to construct an exposure-aware representation
from input blurred frames. We then train two U-Nets for intra-motion and
inter-motion analysis, respectively, adapting to the learned exposure
representation via gain tuning. We finally build our video reconstruction
network upon the exposure and motion representation by progressive
exposure-adaptive convolution and motion refinement. Extensive experiments on
both simulated and real-world datasets show that our optimized method achieves
notable performance gains over the state-of-the-art on the joint video x8
interpolation and deblurring task. Moreover, on the seemingly implausible x16
interpolation task, our method outperforms existing methods by more than 1.5 dB
in terms of PSNR.Comment: Accepted by CVPR 2023, available at
https://github.com/shangwei5/VIDU
Bis[2,6-bis(4,5-dihydro-1H-imidazol-2-yl)pyridine]manganese(II) bis(perchlorate) acetonitrile solvate
In the cation of the title compound, [Mn(C11H13N5)2](ClO4)2·CH3CN, the metal atom is located on a twofold rotation axis and is six-coordinated by six N atoms from two different 2,6-bis(4,5-dihydro-1H-imidazol-2-yl)pyridine (bip) ligands in a distorted octahedral geometry. The O atoms of the perchlorate anions are disordered with occupancies in the ratio 0.593 (10):0.407 (10). In the crystal, molecules are stabilized by two N—H⋯O hydrogen bonds, forming zigzag chains along the a axis, which are further interconnected by N—H⋯O hydrogen bonds and π–π interactions [centroid–centroid distance = 3.50 (1) Å] into a three-dimensional network
Stacking Group Structure of Fermionic Symmetry-Protected Topological Phases
In the past decade, there has been a systematic investigation of
symmetry-protected topological (SPT) phases in interacting fermion systems.
Specifically, by utilizing the concept of equivalence classes of finite-depth
fermionic symmetric local unitary (FSLU) transformations and the decorating
symmetry domain wall picture, a large class of fixed-point wave functions have
been constructed for fermionic SPT (FSPT) phases. Remarkably, this construction
coincides with the Atiyah-Hirzebruch spectral sequence, enabling a complete
classification of FSPT phases. However, unlike bosonic SPT phases, the stacking
group structure in fermion systems proves to be much more intricate. The
construction of fixed-point wave functions does not explicitly provide this
information. In this paper, we employ FSLU transformations to investigate the
stacking group structure of FSPT phases. Specifically, we demonstrate how to
compute stacking FSPT data from the input FSPT data in each layer, considering
both unitary and anti-unitary symmetry, up to 2+1 dimensions. As concrete
examples, we explictly compute the stacking group structure for crystalline
FSPT phases in all 17 wallpaper groups using the fermionic crystalline
equivalence principle. Importantly, our approach can be readily extended to
higher dimensions, offering a versatile method for exploring the stacking group
structure of FSPT phases
Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model
A first principle prediction of the binary nanoparticle phase diagram
assembled by solvent evaporation has eluded theoretical approaches. In this
paper, we show that a binary system interacting through Lennard-Jones (LJ)
potential contains all experimental phases in which nanoparticles are
effectively described as quasi hard spheres. We report a phase diagram
consisting of 53 equilibrium phases, whose stability is quite insensitive to
the microscopic details of the potentials, thus giving rise to some type of
universality. Furthermore, we show that binary lattices may be understood as
consisting of certain particle clusters, i.e. motifs, which provide a
generalization of the four conventional Frank-Kasper polyhedral units. Our
results show that meta-stable phases share the very same motifs as equilibrium
phases. We discuss the connection with packing models, phase diagrams with
repulsive potentials and the prediction of likely experimental superlattices
1,4-Bis(4,5-dihydro-1H-imidazol-2-yl)benzene–4-aminobenzenesulfonic acid–water (1/2/2)
The asymmetric unit of the title compound, C12H14N4·2C6H7NO3S·2H2O, contains one half of a centrosymmetric 1,4-bis(4,5-dihydro-1H-imidazol-2-yl)benzene (bib) molecule, one 4-aminobenzenesulfonic acid molecule and one water molecule. In the bib molecule, the imidazole ring adopts an envelope conformation. The benzene rings of bib and 4-aminobenzenesulfonic acid are oriented at a dihedral angle of 21.89 (4)°. In the crystal structure, intermolecular N—H⋯O, O—H⋯N and O—H⋯O interactions link the molecules into a three-dimensional network. Weak π–π contacts between the benzene and imidazole rings and between the benzene rings [centroid–centroid distances = 3.895 (1) and 3.833 (1) Å, respectively] may further stabilize the structure
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