2,184 research outputs found
Cooling mechanical resonators to quantum ground state from room temperature
Ground-state cooling of mesoscopic mechanical resonators is a fundamental
requirement for test of quantum theory and for implementation of quantum
information. We analyze the cavity optomechanical cooling limits in the
intermediate coupling regime, where the light-enhanced optomechanical coupling
strength is comparable with the cavity decay rate. It is found that in this
regime the cooling breaks through the limits in both the strong and weak
coupling regimes. The lowest cooling limit is derived analytically at the
optimal conditions of cavity decay rate and coupling strength. In essence,
cooling to the quantum ground state requires , with being the mechanical quality factor and
being the thermal phonon number. Remarkably, ground-state
cooling is achievable starting from room temperature, when mechanical
-frequency product , and both of the
cavity decay rate and the coupling strength exceed the thermal decoherence
rate. Our study provides a general framework for optimizing the backaction
cooling of mesoscopic mechanical resonators
GPA-Net:No-Reference Point Cloud Quality Assessment with Multi-task Graph Convolutional Network
With the rapid development of 3D vision, point cloud has become an
increasingly popular 3D visual media content. Due to the irregular structure,
point cloud has posed novel challenges to the related research, such as
compression, transmission, rendering and quality assessment. In these latest
researches, point cloud quality assessment (PCQA) has attracted wide attention
due to its significant role in guiding practical applications, especially in
many cases where the reference point cloud is unavailable. However, current
no-reference metrics which based on prevalent deep neural network have apparent
disadvantages. For example, to adapt to the irregular structure of point cloud,
they require preprocessing such as voxelization and projection that introduce
extra distortions, and the applied grid-kernel networks, such as Convolutional
Neural Networks, fail to extract effective distortion-related features.
Besides, they rarely consider the various distortion patterns and the
philosophy that PCQA should exhibit shifting, scaling, and rotational
invariance. In this paper, we propose a novel no-reference PCQA metric named
the Graph convolutional PCQA network (GPA-Net). To extract effective features
for PCQA, we propose a new graph convolution kernel, i.e., GPAConv, which
attentively captures the perturbation of structure and texture. Then, we
propose the multi-task framework consisting of one main task (quality
regression) and two auxiliary tasks (distortion type and degree predictions).
Finally, we propose a coordinate normalization module to stabilize the results
of GPAConv under shift, scale and rotation transformations. Experimental
results on two independent databases show that GPA-Net achieves the best
performance compared to the state-of-the-art no-reference PCQA metrics, even
better than some full-reference metrics in some cases
Changes in Climate Extremes and Catastrophic Events in the Mongolian Plateau from 1951 to 2012
AbstractThe spatiotemporal changes in 21 indices of extreme temperature and precipitation for the Mongolian Plateau from 1951 to 2012 were investigated on the basis of daily temperature and precipitation data from 70 meteorological stations. Changes in catastrophic events, such as droughts, floods, and snowstorms, were also investigated for the same period. The correlations between catastrophic events and the extreme indices were examined. The results show that the Mongolian Plateau experienced an asymmetric warming trend. Both the cold extremes and warm extremes showed greater warming at night than in the daytime. The spatial changes in significant trends showed a good homogeneity and consistency in Inner Mongolia. Changes in the precipitation extremes were not as obvious as those in the temperature extremes. The spatial distributions in changes of precipitation extremes were complex. A decreasing trend was shown for total precipitation from west to east as based on the spatial distribution of decadal trends. Drought was the most serious extreme disaster, and prolonged drought for longer than 3 yr occurred about every 7–11 yr. An increasing trend in the disaster area was apparent for flood events from 1951 to 2012. A decreasing trend was observed for the maximum depth of snowfall from 1951 to 2012, with a decreased average maximum depth of 10 mm from the 1990s.</jats:p
Multi-Domain Learning From Insufficient Annotations
Multi-domain learning (MDL) refers to simultaneously constructing a model or
a set of models on datasets collected from different domains. Conventional
approaches emphasize domain-shared information extraction and domain-private
information preservation, following the shared-private framework (SP models),
which offers significant advantages over single-domain learning. However, the
limited availability of annotated data in each domain considerably hinders the
effectiveness of conventional supervised MDL approaches in real-world
applications. In this paper, we introduce a novel method called multi-domain
contrastive learning (MDCL) to alleviate the impact of insufficient annotations
by capturing both semantic and structural information from both labeled and
unlabeled data.Specifically, MDCL comprises two modules: inter-domain semantic
alignment and intra-domain contrast. The former aims to align annotated
instances of the same semantic category from distinct domains within a shared
hidden space, while the latter focuses on learning a cluster structure of
unlabeled instances in a private hidden space for each domain. MDCL is readily
compatible with many SP models, requiring no additional model parameters and
allowing for end-to-end training. Experimental results across five textual and
image multi-domain datasets demonstrate that MDCL brings noticeable improvement
over various SP models.Furthermore, MDCL can further be employed in
multi-domain active learning (MDAL) to achieve a superior initialization,
eventually leading to better overall performance.Comment: This paper has been accepted to ECAI-2
Dydrogesterone has no effect on uterine fibroids when used to prevent miscarriage in pregnant women with uterine fibroids
Objectives: To analyse the effect of dydrogesterone use during pregnancy on uterine fibroids, pregnancy complications, and pregnancy outcome.
Material and methods: In all, 372 pregnant women with uterine fibroids who were treated at the Affiliated Provincial Hospital of Shandong University were included in this study. Thirty-three of these women received dydrogesterone and constituted the treatment group, and the 27 women who were found to have uterine fibroids during the first trimester but did not receive intervention to prevent miscarriage composed the control group. The changes in uterine fibroids before and after pregnancy and the pregnancy complications were recorded; immunohistochemistry was used to detect the expression of progesterone receptor (PR) and proliferation- and apoptosis-related proteins in the uterine fibroid tissue.
Results: No significant difference was observed in the change in uterine fibroid volume during pregnancy between the treatment group and the control group (p > 0.05). The percentage of uterine fibroids with red degeneration was lower in the treatment group than in the control group, but the difference was not statistically significant. No significant difference was observed in newborn weight, height, Apgar score, threatened miscarriage, or premature birth, among other characteristics, between the two groups (p > 0.05). Immunohistochemistry showed no significant difference in the expression of PR, cyclinD1, insulin-like growth factor (IGF1), or B-cell lymphoma 2 (Bcl2) between the two groups.
Conclusions: The use of dydrogesterone during pregnancy has no significant effect on uterine fibroids, pregnancy progression, or pregnancy outcomes in pregnant patients with uterine fibroids
5-Bromo-2-iodo-1,3-dimethylbenzene
The asymmetric unit of the title compound, C8H8BrI, contains three independent molecules. In each molecule, the Br, I and C atoms of the methyl groups lie in the benzene ring plane. Intramolecular C—H⋯I hydrogen bonds result in the formation of three planar five-membered rings, which are nearly coplanar with the adjacent rings
4-Bromo-2,6-dimethylaniline
The asymmetric unit of the title compound, C8H10BrN, contains two independent molecules. The Br, N and methyl group C atoms lie in the benzene ring planes. In the crystal structure, N—H⋯N hydrogen bonds link the molecules
1-Diphenylphosphino-1′-(diphenylphosphinoyl)cobaltocenium hexafluoridophosphate
The title compound, [Co(C17H14OP)(C17H14P)]PF6, was obtained unintentionally as the product of an attempted synthesis of [1,1′-bis(oxodiphenylphosphoranyl)cobaltocenium] hexafluoridophosphate. The O atom of the oxo group is disordered over two positions with site occupancies of 0.65:0.35. The crystal structure contains weak intermolecular C—H⋯F hydrogen bonds, connecting the components of the structure into chains parallel to [010]
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