326 research outputs found
OmniLocalRF: Omnidirectional Local Radiance Fields from Dynamic Videos
Omnidirectional cameras are extensively used in various applications to
provide a wide field of vision. However, they face a challenge in synthesizing
novel views due to the inevitable presence of dynamic objects, including the
photographer, in their wide field of view. In this paper, we introduce a new
approach called Omnidirectional Local Radiance Fields (OmniLocalRF) that can
render static-only scene views, removing and inpainting dynamic objects
simultaneously. Our approach combines the principles of local radiance fields
with the bidirectional optimization of omnidirectional rays. Our input is an
omnidirectional video, and we evaluate the mutual observations of the entire
angle between the previous and current frames. To reduce ghosting artifacts of
dynamic objects and inpaint occlusions, we devise a multi-resolution motion
mask prediction module. Unlike existing methods that primarily separate dynamic
components through the temporal domain, our method uses multi-resolution neural
feature planes for precise segmentation, which is more suitable for long
360-degree videos. Our experiments validate that OmniLocalRF outperforms
existing methods in both qualitative and quantitative metrics, especially in
scenarios with complex real-world scenes. In particular, our approach
eliminates the need for manual interaction, such as drawing motion masks by
hand and additional pose estimation, making it a highly effective and efficient
solution
OmniSDF: Scene Reconstruction using Omnidirectional Signed Distance Functions and Adaptive Binoctrees
We present a method to reconstruct indoor and outdoor static scene geometry
and appearance from an omnidirectional video moving in a small circular sweep.
This setting is challenging because of the small baseline and large depth
ranges, making it difficult to find ray crossings. To better constrain the
optimization, we estimate geometry as a signed distance field within a
spherical binoctree data structure and use a complementary efficient tree
traversal strategy based on a breadth-first search for sampling. Unlike regular
grids or trees, the shape of this structure well-matches the camera setting,
creating a better memory-quality trade-off. From an initial depth estimate, the
binoctree is adaptively subdivided throughout the optimization; previous
methods use a fixed depth that leaves the scene undersampled. In comparison
with three neural optimization methods and two non-neural methods, ours shows
decreased geometry error on average, especially in a detailed scene, while
significantly reducing the required number of voxels to represent such details
Peptidyl-prolyl cis/trans isomerase Pin1 interacts with hepatitis B virus core particle, but not with HBc protein, to promote HBV replication
Here, we demonstrate that the peptidyl-prolyl cis/trans isomerase Pin1 interacts noncovalently with the hepatitis B virus (HBV) core particle through phosphorylated serine/threonine-proline (pS/TP) motifs in the carboxyl-terminal domain (CTD) but not with particle-defective, dimer-positive mutants of HBc. This suggests that neither dimers nor monomers of HBc are Pin1-binding partners. The 162TP, 164SP, and 172SP motifs within the HBc CTD are important for the Pin1/core particle interaction. Although Pin1 dissociated from core particle upon heat treatment, it was detected as an opened-up core particle, demonstrating that Pin1 binds both to the outside and the inside of the core particle. Although the amino-terminal domain S/TP motifs of HBc are not involved in the interaction, 49SP contributes to core particle stability, and 128TP might be involved in core particle assembly, as shown by the decreased core particle level of S49A mutant through repeated freeze and thaw and low-level assembly of the T128A mutant, respectively. Overexpression of Pin1 increased core particle stability through their interactions, HBV DNA synthesis, and virion secretion without concomitant increases in HBV RNA levels, indicating that Pin1 may be involved in core particle assembly and maturation, thereby promoting the later stages of the HBV life cycle. By contrast, parvulin inhibitors and PIN1 knockdown reduced HBV replication. Since more Pin1 proteins bound to immature core particles than to mature core particles, the interaction appears to depend on the stage of virus replication. Taken together, the data suggest that physical association between Pin1 and phosphorylated core particles may induce structural alterations through isomerization by Pin1, induce dephosphorylation by unidentified host phosphatases, and promote completion of virus life cycle
Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions
We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC
Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe
Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV
Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe
Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV
Peer reviewe
Pseudorapidity and transverse-momentum distributions of charged particles in proton-proton collisions at root s=13 TeV
The pseudorapidity (eta) and transverse-momentum (p(T)) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy root s = 13 TeV. The pseudorapidity distribution in vertical bar eta vertical bar <1.8 is reported for inelastic events and for events with at least one charged particle in vertical bar eta vertical bar <1. The pseudorapidity density of charged particles produced in the pseudorapidity region vertical bar eta vertical bar <0.5 is 5.31 +/- 0.18 and 6.46 +/- 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 <p(T) <20 GeV/c and vertical bar eta vertical bar <0.8 for events with at least one charged particle in vertical bar eta vertical bar <1. The evolution of the transverse momentum spectra of charged particles is also investigated as a function of event multiplicity. The results are compared with calculations from PYTHIA and EPOS Monte Carlo generators. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV
The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe
Using di-hadron correlations to investigate jet modifications in Pb-Pb collisions with ALICE
The comparison of jets measured in heavy-ion collisions with jets measured in pp collisions is a rich source of information on jet-medium interactions. These medium-induced modifications can be prominent at low transverse momentum , where traditional jet reconstruction tools are difficult to use. The measurement of di-hadron correlations provide an alternative way to study jets in this regime. Calculating the pseudorapidity () and azimuthal angle () differences between trigger and associated particles, one observes the manifestation of the jet fragmentation as a peak around (,)=(0,0). The modification factor is defined as the yield of the jet-like peak in Pb-Pb divided by the corresponding yield in pp collisions at the same energy. In this contribution, we will present the latest ALICE measurements of with charged hadrons from collisions with a center of mass energy per nucleon-nucleon pair of 2.76 TeV. We observe that the -dependent shows a narrowing in pseudorapidity in central collisions for trigger particles with a high . We also investigate the path-length dependence of jet modification by measuring as a function of the relative angle between the trigger particle and the event plane. These measurements are compared to model calculations, and are expected to place strong constraints on energy loss models
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