89 research outputs found
Conformal Field Theories generated by Chern Insulators under Quantum Decoherence
We demonstrate that the fidelity between a pure state trivial insulator and
the mixed state density matrix of a Chern insulator under decoherence can be
mapped to a variety of two-dimensional conformal field theories (CFT); more
specifically, the quantity is mapped to the partition function of the desired CFT,
where and are respectively the density
matrices of the decohered Chern insulator and a pure state trivial insulator.
For a pure state Chern insulator with Chern number , the fidelity
is mapped to the partition function of the CFT;
under weak decoherence, the Chern insulator density matrix can experience
certain instability, and the "partition function" can flow to
other interacting CFTs with smaller central charges. The R\'{e}nyi relative
entropy
is mapped to the free energy of the CFT, and we demonstrate that the central
charge of the CFT can be extracted from the finite size scaling of
, analogous to the well-known finite size scaling of CFT.Comment: 8.5 pages, including reference
A Multicritical Point with Infinite Fractal Symmetries
Recently a ``Pascal's triangle model" constructed with rotor
degrees of freedom was introduced, and it was shown that (.) this
model possesses an infinite series of fractal symmetries; and (.)
it is the parent model of a series of fractal models each with its own
distinct fractal symmetry. In this work we discuss a multi-critical point of
the Pascal's triangle model that is analogous to the Rokhsar-Kivelson (RK)
point of the better known quantum dimer model. We demonstrate that the
expectation value of the characteristic operator of each fractal symmetry at
this multi-critical point decays as a power-law of space, and this
multi-critical point is shared by the family of descendent fractal
models. Afterwards, we generalize our discussion to a model termed the
``Pascal's tetrahedron model" that has both planar and fractal subsystem
symmetries. We also establish a connection between the Pascal's tetrahedron
model and the Haah's code.Comment: 10.5 pages, 4 figure
AdaptNet: Policy Adaptation for Physics-Based Character Control
Motivated by humans' ability to adapt skills in the learning of new ones,
this paper presents AdaptNet, an approach for modifying the latent space of
existing policies to allow new behaviors to be quickly learned from like tasks
in comparison to learning from scratch. Building on top of a given
reinforcement learning controller, AdaptNet uses a two-tier hierarchy that
augments the original state embedding to support modest changes in a behavior
and further modifies the policy network layers to make more substantive
changes. The technique is shown to be effective for adapting existing
physics-based controllers to a wide range of new styles for locomotion, new
task targets, changes in character morphology and extensive changes in
environment. Furthermore, it exhibits significant increase in learning
efficiency, as indicated by greatly reduced training times when compared to
training from scratch or using other approaches that modify existing policies.
Code is available at https://motion-lab.github.io/AdaptNet.Comment: SIGGRAPH Asia 2023. Video: https://youtu.be/WxmJSCNFb28. Website:
https://motion-lab.github.io/AdaptNet, https://pei-xu.github.io/AdaptNe
Signal identification with Kalman Filter towards background-free neutrinoless double beta decay searches in gaseous detectors
Particle tracks and differential energy loss measured in high pressure
gaseous detectors can be exploited for event identification in neutrinoless
double beta decay~() searches. We develop a new method based
on Kalman Filter in a Bayesian formalism (KFB) to reconstruct meandering tracks
of MeV-scale electrons. With simulation data, we compare the signal and
background discrimination power of the KFB method assuming different detector
granularities and energy resolutions. Typical background from Th and
U decay chains can be suppressed by another order of magnitude than
that in published literatures, approaching the background-free regime. For the
proposed PandaX-III experiment, the search half-life
sensitivity at the 90\% confidence level would reach ~yr
with 5-year live time, a factor of 2.7 improvement over the initial design
target
NLRP6 Serves as a Negative Regulator of Neutrophil Recruitment and Function During Streptococcus pneumoniae Infection
Streptococcus pneumoniae is an invasive pathogen with high morbidity and mortality in the immunocompromised children and elderly. NOD-like receptor family pyrin domain containing 6 (NLRP6) plays an important role in the host innate immune response against pathogen infections. Our previous studies have shown that NLRP6 plays a negative regulatory role in host defense against S. pneumoniae, but the underlying mechanism is still unclear. The further negative regulatory role of NLRP6 in the host was investigated in this study. Our results showed that NLRP6(-/-) mice in the lung had lower bacterial burdens after S. pneumoniae infection and expressed higher level of tight junction (TJ) protein occludin compared to WT mice, indicating the detrimental role of NLRP6 in the host defense against S. pneumoniae infection. Transcriptome analysis showed that genes related to leukocytes migration and recruitment were differentially expressed between wild-type (WT) and NLRP6 knockout (NLRP6(-/-)) mice during S. pneumoniae infection. Also, NLRP6(-/-) mice showed higher expression of chemokines including C-X-C motif chemokine ligand 1 (CXCL1) and 2 (CXCL2) and lower gene expression of complement C3a receptor 1 (C3aR1) and P-selectin glycoprotein ligand-1 (PSGL-1) which are the factors that inhibit the recruitment of neutrophils. Furthermore, NLRP6(-/-) neutrophils showed increased intracellular bactericidal ability and the formation of neutrophil extracellular traps (NETs) during S. pneumoniae infection. Taken together, our study suggests that NLRP6 is a negative regulator of neutrophil recruitment and function during S. pneumoniae infection. Our study provides a new insight to develop novel strategies to treat invasive pneumococcal infection
Frustrated magnetic interactions in a Wigner-Mott insulator
Two-dimensional semiconductor moir\'e materials have emerged as a highly
controllable platform to simulate and explore quantum condensed matter.
Compared to real solids, electrons in semiconductor moir\'e materials are less
strongly attracted to the moir\'e lattice sites, making the nonlocal
contributions to the magnetic interactions as important as the Anderson
super-exchange. It provides a unique platform to study the effects of competing
magnetic interactions. Here, we report the observation of strongly frustrated
magnetic interactions in a Wigner-Mott insulating state at 2/3 filling of the
moir\'e lattice in angle-aligned WSe2/WS2 heterobilayers. Magneto-optical
measurements show that the net exchange interaction is antiferromagnetic for
filling factors below 1 with a strong suppression at 2/3 filling. The
suppression is lifted upon screening of the long-range Coulomb interactions and
melting of the Wigner-Mott insulator by a nearby metallic gate. The results can
be qualitatively captured by a honeycomb-lattice spin model with an
antiferromagnetic nearest-neighbor coupling and a ferromagnetic second-neighbor
coupling. Our study establishes semiconductor moir\'e materials as a model
system for the lattice-spin physics and frustrated magnetism
Efficient generation of P53 biallelic knockout Diannan miniature pigs via TALENs and somatic cell nuclear transfer
Jet characteristics and optimal design of hydraulic perforating nozzles for natural gas hydrate reservoirs
Jet nozzle is a core component of the hydraulic perforating fracturing tool, and the design of the nozzle structure directly affects the perforating effectiveness and efficiency. In this paper, the flow field characteristics of hydraulic perforating nozzles are calculated by the SST k - ω turbulence model. The results show that the nozzle structure parameters significantly influence the jet performance. Through orthogonal experiments, the conical-cylindrical nozzle geometric parameters are preliminarily optimized as follows: the cylindrical segment diameter is 6 mm, the contraction angle is 10°, the contraction segment length is 8 mm, and the cylindrical segment length is 12 mm. The results can provide theoretical guidance for later experimental research on jet rock breaking and optimization design of the jet tools
Consolidation-acidizing experiments on methane natural gas sediment skeleton
During the development of natural gas hydrates, it is important to ensure the stability of the reservoir. The hydrate reservoirs in the South China Sea are clayey silt sediments, which are prone to sand production and collapse during hydrate dissociation. This study innovatively proposes the idea of consolidation-acidizing for NGH reservoir modification. Based on the core parameters of well A drilling in the Shenhu Sea area of the South China Sea, NGH sediment skeleton samples were artificially prepared. Core sensitivity testing indicates that the NGH reservoir has the potential for acidizing modification. After using tetraethyl orthosilicate to solidify the sample, it was found that Young’s modulus of the sample increased by 58.8%, and the compressive strength increased by 54.78%. Although the porosity decreased by 39.33%, the pores were not completely blocked. After the acidizing experiment, the permeability of the consolidated sample was 2.88 mD, and the porosity increased by 10.63%; The permeability of the unconsolidated sample was 1.86 mD, and the porosity decreased by 10.73%. The CT scan images also showed that the pores of the sample after consolidation-acidizing developed uniformly without significant deformation; The unconsolidated sample undergoes severe deformation and sand production after acidizing. This study demonstrates that the consolidation-acidizing modification method is feasible in clayey silt hydrate reservoirs
- …