4,276 research outputs found
Symmetry enhanced first-order phase transition in a two-dimensional quantum magnet
Theoretical studies of quantum phase transitions have suggested critical points with higher symmetries than those of the underlying Hamiltonian. Here we demonstrate a surprising emergent symmetry of the coexistence state at a strongly discontinuous phase transition between two ordered ground states. We present a quantum Monte Carlo study of a two-dimensional S=1/2 quantum magnet hosting the antiferromagnetic (AFM) and plaquette-singlet solid (PSS) states recently detected in SrCu2(BO3)2. We observe that the O(3) symmetric AFM order and the Z2 symmetric PSS order form an O(4) vector at the transition. The control parameter g (a coupling ratio) rotates the vector between the AFM and PSS sectors and there are no energy barriers between the two at the transition point gc. This phenomenon may be observable in SrCu2(BO3)2.First author draf
Master of Science
thesisWe identify an interdecadal oscillatory mode of the North Atlantic atmosphere-ocean system via a Linear Inverse Model (LIM). This mode is shown to be related to the interior pathway propagation of Atlantic Meridional Overturning Circulation (AMOC) anomalies. The oscillation is an ocean-only mode while excited by atmospheric forcing; in particular, it can be approximated as a linearly driven damped oscillator while the North Atlantic Oscillation (NAO) acts as part of the ''external" force. We also show that the influence of NAO-induced surface wind stress forcing quickly damps while the NAO-induced deep flow anomaly, integrating with ocean topography, plays a crucial role in this interdecadal mode. Including such deep ocean dynamics besides surface temperature (SST) significantly improves and prolongs the LIM's prediction skill of SST evolution
Research on Effects of Chinese Current Tax System Adjustment on Income Distribution of Urban Residents
This article analyzes the adjustment effect of Chinese current tax system on income gap among urban residents, using statistical and econometric research methods, and a series of the Gini coefficient, income equality index and etc. to calculate and compare income disparity of urban residents in the existing tax system. The research result shows that the existing tax system has hardly any effect on income distribution of urban residents. Thus the last part of this article puts forward some suggestions to the government on how to reform currently tax system in order to improve people's livelihood, and promote harmonious development. Key words: Tax system; Income gap; Adjustment effects RĂ©sumĂ©: Cet article analyse l'effet de l'ajustement de l'actuel rĂ©gime fiscal chinois sur l'Ă©cart des revenus entre les habitants urbains, en utilisant des mĂ©thodes de recherche statistique et Ă©conomĂ©trique, ainsi qu'une sĂ©rie de coefficients de Gini, l'indice de l'Ă©galitĂ© des revenus afin de calculer et de comparer les disparitĂ©s de revenus des rĂ©sidents urbains dans la l'actuel rĂ©gime fiscal. Le rĂ©sultat de la recherche montre que le systĂšme fiscal actuel n'a guĂšre d'effet sur la rĂ©partition des revenus des rĂ©sidents urbains. Ainsi, la derniĂšre partie de cet article met en avant quelques suggestions au gouvernement sur la façon de rĂ©former l'actuel systĂšme fiscal en vue d'amĂ©liorer la vie du peuple, et de promouvoir un dĂ©veloppement harmonieux. Mots-clĂ©s: SystĂšme fiscal; Ăcart des revenues; Effets d'ajustemen
Reconstructing 3D Human Pose from RGB-D Data with Occlusions
We propose a new method to reconstruct the 3D human body from RGB-D images
with occlusions. The foremost challenge is the incompleteness of the RGB-D data
due to occlusions between the body and the environment, leading to implausible
reconstructions that suffer from severe human-scene penetration. To reconstruct
a semantically and physically plausible human body, we propose to reduce the
solution space based on scene information and prior knowledge. Our key idea is
to constrain the solution space of the human body by considering the occluded
body parts and visible body parts separately: modeling all plausible poses
where the occluded body parts do not penetrate the scene, and constraining the
visible body parts using depth data. Specifically, the first component is
realized by a neural network that estimates the candidate region named the
"free zone", a region carved out of the open space within which it is safe to
search for poses of the invisible body parts without concern for penetration.
The second component constrains the visible body parts using the "truncated
shadow volume" of the scanned body point cloud. Furthermore, we propose to use
a volume matching strategy, which yields better performance than surface
matching, to match the human body with the confined region. We conducted
experiments on the PROX dataset, and the results demonstrate that our method
produces more accurate and plausible results compared with other methods
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On the genesis and dynamics of MaddenâJulian oscillationâlike structure formed by equatorial adjustment of localized heating
By means of a new multilayer pseudoâspectral moistâconvective thermal rotating shallowâwater (mcTRSW) model in a full sphere, we present a possible equatorial adjustment beyond Gill's mechanism for the genesis and dynamics of the MaddenâJulian oscillation (MJO). According to this theory, an eastwardâpropagating MJOâlike structure can be generated in a selfâsustained and selfâpropelled manner due to nonlinear relaxation (adjustment) of a largeâscale positive buoyancy anomaly, depressed anomaly, or a combination of these, as soon as this anomaly reaches a critical threshold in the presence of moist convection at the Equator. This MJOâlike episode possesses a convectively coupled âhybrid structureâ that consists of a âquasiâequatorial modonâ with an enhanced vortex pair and a convectively coupled baroclinic Kelvin wave (BKW), with greater phase speed than that of dipolar structure on an intraseasonal timeâscale. Interaction of the BKW, after circumnavigating the entire Equator, with a new largeâscale buoyancy anomaly may contribute to excitation of a recurrent generation of the next cycle of MJOâlike structure. Overall, the generated âhybrid structureâ captures a few of the crudest features of the MJO, including its quadrupolar structure, convective activity, condensation patterns, vorticity field, phase speed, and westerly and easterly inflows in the lower and upper troposphere. Although moistureâfed convection is a necessary condition for the âhybrid structureâ to be excited and maintained in the proposed theory in this study, it is fundamentally different from moistureâmode theories, because the barotropic equatorial modon and BKW also exist in âdryâ environments, while there are no similar âdryâ dynamical basic structures in moistureâmode theories. The proposed theory can therefore be a possible mechanism to explain the genesis and backbone structure of the MJO and to converge some theories that previously seemed divergent. By means of a new multilayer pseudoâspectral moistâconvective thermal rotating shallowâwater model in a full sphere, we present a mechanism in which geostrophic adjustment of largeâscale localized heating in the lower troposphere over the equatorial zone can lead to generation of a structure similar to that of the MaddenâJulian oscillation
ZeroGen: Zero-shot Multimodal Controllable Text Generation with Multiple Oracles
Automatically generating textual content with desired attributes is an
ambitious task that people have pursued long. Existing works have made a series
of progress in incorporating unimodal controls into language models (LMs),
whereas how to generate controllable sentences with multimodal signals and high
efficiency remains an open question. To tackle the puzzle, we propose a new
paradigm of zero-shot controllable text generation with multimodal signals
(\textsc{ZeroGen}). Specifically, \textsc{ZeroGen} leverages controls of text
and image successively from token-level to sentence-level and maps them into a
unified probability space at decoding, which customizes the LM outputs by
weighted addition without extra training. To achieve better inter-modal
trade-offs, we further introduce an effective dynamic weighting mechanism to
regulate all control weights. Moreover, we conduct substantial experiments to
probe the relationship of being in-depth or in-width between signals from
distinct modalities. Encouraging empirical results on three downstream tasks
show that \textsc{ZeroGen} not only outperforms its counterparts on captioning
tasks by a large margin but also shows great potential in multimodal news
generation with a higher degree of control. Our code will be released at
https://github.com/ImKeTT/ZeroGen.Comment: 17 pages, preprin
Symmetry enhanced first-order phase transition in a two-dimensional quantum magnet
Theoretical studies of quantum phase transitions have suggested critical
points with higher symmetries than those of the underlying Hamiltonian. Here we
demonstrate a surprising emergent symmetry of the coexistence state at a
strongly discontinuous phase transition between two ordered ground states. We
present a quantum Monte Carlo study of a two-dimensional quantum magnet
hosting the antiferromagnetic (AFM) and plaquette-singlet solid (PSS) states
recently detected in SrCu(BO). We observe that the O(3) symmetric
AFM order and the Z symmetric PSS order form an O(4) vector at the
transition. The control parameter (a coupling ratio) rotates the vector
between the AFM and PSS sectors and there are no energy barriers between the
two at the transition point . This phenomenon may be observable in
SrCu(BO).Comment: 12 pages, 12 figure
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