246 research outputs found
Synthesis and Biological Study of Adenylyl Cyclase Inhibitors
Adenylyl cyclases (AC) is a critical family of enzymes which modulates the dynamic cellular level of cAMP, cyclic adenosine monophosphate. The study of cAMP showed that it is indispensable for the signal transduction cascades during many physiological processes, such as immune responses and metabolism which highly relate to cancers. Previous studies of AC inhibitors have been limited due to a lack of isoform-selective small molecule modulators. Selectivity of the molecules is imperative to the activation of only the desired AC inhibitor. The design of the described project was to test the structure activity relationship (SAR) by synthesizing a class of AC I inhibitors and then use the results to develop a small molecule with maximum selectivity for therapeutic targeting. Multi-step synthesis featured with epoxide ring-opening reaction followed by the Friedel–Crafts reaction. Compounds were differentiated by changing substituents on the nitrogen atom. The synthetic molecules have been tested via SAR of AC I inhibitor and IC50. Once synthesized, the compounds were tested for their inhibition rate and the results showed that the majority of scaffolds had great SAR rates at 40 µM and two also had impressive rates as low as 4 µM. Further investigation with IC50 studies is on-going. The results suggest that the current synthetic compounds are potentially great AC I inhibitors and further study will continue which will contribute to cancer research
Joint Token Pruning and Squeezing Towards More Aggressive Compression of Vision Transformers
Although vision transformers (ViTs) have shown promising results in various
computer vision tasks recently, their high computational cost limits their
practical applications. Previous approaches that prune redundant tokens have
demonstrated a good trade-off between performance and computation costs.
Nevertheless, errors caused by pruning strategies can lead to significant
information loss. Our quantitative experiments reveal that the impact of pruned
tokens on performance should be noticeable. To address this issue, we propose a
novel joint Token Pruning & Squeezing module (TPS) for compressing vision
transformers with higher efficiency. Firstly, TPS adopts pruning to get the
reserved and pruned subsets. Secondly, TPS squeezes the information of pruned
tokens into partial reserved tokens via the unidirectional nearest-neighbor
matching and similarity-based fusing steps. Compared to state-of-the-art
methods, our approach outperforms them under all token pruning intensities.
Especially while shrinking DeiT-tiny&small computational budgets to 35%, it
improves the accuracy by 1%-6% compared with baselines on ImageNet
classification. The proposed method can accelerate the throughput of DeiT-small
beyond DeiT-tiny, while its accuracy surpasses DeiT-tiny by 4.78%. Experiments
on various transformers demonstrate the effectiveness of our method, while
analysis experiments prove our higher robustness to the errors of the token
pruning policy. Code is available at
https://github.com/megvii-research/TPS-CVPR2023.Comment: Accepted to CVPR202
Constrained Multiview Representation for Self-supervised Contrastive Learning
Representation learning constitutes a pivotal cornerstone in contemporary deep learning paradigms, offering a conduit to elucidate distinctive features within the latent space and interpret the deep models. Nevertheless, the inherent complexity of anatomical patterns and the random nature of lesion distribution in medical image segmentation pose significant challenges to the disentanglement of representations and the understanding of salient features. Methods guided by the maximization of mutual information, particularly within the framework of contrastive learning, have demonstrated remarkable success and superiority in decoupling densely intertwined representations. However, the effectiveness of contrastive learning highly depends on the quality of the positive and negative sample pairs, i.e. the unselected average mutual information among multi-views would obstruct the learning strategy so the selection of the views is vital. In this work, we introduce a novel approach predicated on representation distance-based mutual information (MI) maximization for measuring the significance of different views, aiming at conducting more efficient contrastive learning and representation disentanglement. Additionally, we introduce an MI re-ranking strategy for representation selection, benefiting both the continuous MI estimating and representation significance distance measuring. Specifically, we harness multi-view representations extracted from the frequency domain, re-evaluating their significance based on mutual information across varying frequencies, thereby facilitating a multifaceted contrastive learning approach to bolster semantic comprehension. The statistical results under the five metrics demonstrate that our proposed framework proficiently constrains the MI maximization-driven representation selection and steers the multi-view contrastive learning process
Excitation of extraordinary modes inside the source of Saturn's kilometric radiation
The electron cyclotron maser instability (ECMI) of extraordinary mode waves
was investigated with the parameters observed in Saturn's kilometric radiation
(SKR) sources. Previous studies employed simplified dispersion relations, and
did not consider the excitation of the relativistic (R) mode. This mode is
introduced by considering the relativistic effect in plasmas consisting of both
cold and hot electrons. Using particle-in-cell simulations, we investigated the
excitation of R and X modes based on the measured data. Using the reported
value of the density ratio of energetic to total electrons , the
most unstable mode is the R mode. The escaping X-mode emissions are amplified
only if the energetic electrons are dominant with . For these
cases, only the X mode is excited and the R mode disappears due to its strong
coupling. The results are well in line with the linear kinetic theory of ECMI.
The properties of both the R and X modes are consistent with the observed SKR
emissions. This raises questions about the nature of the measured electric
field fluctuations within ``presumed'' SKR sources. The study provides new
insights into the ECMI process relevant to SKR emission mechanisms
Efficient Meta Neural Heuristic for Multi-Objective Combinatorial Optimization
Recently, neural heuristics based on deep reinforcement learning have
exhibited promise in solving multi-objective combinatorial optimization
problems (MOCOPs). However, they are still struggling to achieve high learning
efficiency and solution quality. To tackle this issue, we propose an efficient
meta neural heuristic (EMNH), in which a meta-model is first trained and then
fine-tuned with a few steps to solve corresponding single-objective
subproblems. Specifically, for the training process, a (partial)
architecture-shared multi-task model is leveraged to achieve parallel learning
for the meta-model, so as to speed up the training; meanwhile, a scaled
symmetric sampling method with respect to the weight vectors is designed to
stabilize the training. For the fine-tuning process, an efficient hierarchical
method is proposed to systematically tackle all the subproblems. Experimental
results on the multi-objective traveling salesman problem (MOTSP),
multi-objective capacitated vehicle routing problem (MOCVRP), and
multi-objective knapsack problem (MOKP) show that, EMNH is able to outperform
the state-of-the-art neural heuristics in terms of solution quality and
learning efficiency, and yield competitive solutions to the strong traditional
heuristics while consuming much shorter time.Comment: Accepted at NeurIPS 202
Towards Benchmarking GUI Compatibility Testing on Mobile Applications
GUI is a bridge connecting user and application. Existing GUI testing tasks
can be categorized into two groups: functionality testing and compatibility
testing. While the functionality testing focuses on detecting application
runtime bugs, the compatibility testing aims at detecting bugs resulting from
device or platform difference. To automate testing procedures and improve
testing efficiency, previous works have proposed dozens of tools. To evaluate
these tools, in functionality testing, researchers have published testing
benchmarks. Comparatively, in compatibility testing, the question of ``Do
existing methods indeed effectively assist test cases replay?'' is not well
answered. To answer this question and advance the related research in GUI
compatibility testing, we propose a benchmark of GUI compatibility testing. In
our experiments, we compare the replay success rate of existing tools. Based on
the experimental results, we summarize causes which may lead to ineffectiveness
in test case replay and propose opportunities for improving the
state-of-the-art
Coupled superconducting qudit-resonator system: Energy spectrum, state population, and state transition under microwave drive
Superconducting quantum multilevel systems coupled to resonators have recently been considered in some
applications such as microwave lasing and high-fidelity quantum logical gates. In this work, using an rf-SQUID
type phase qudit coupled to a microwave coplanar waveguide resonator, we study both theoretically and
experimentally the energy spectrum of the system when the qudit level spacings are varied around the resonator
frequency by changing the magnetic flux applied to the qudit loop. We show that the experimental result can
be well described by a theoretical model that extends from the usual two-level Jaynes-Cummings system to the
present four-level system. It is also shown that due to the small anharmonicity of the phase device a simplified
model capturing the leading state interactions fits the experimental spectra very well. Furthermore we use the
Lindblad master equation containing various relaxation and dephasing processes to calculate the level populations
in the simpler qutrit-resonator system, which allows a clear understanding of the dynamics of the system under
the microwave drive. Our results help to better understand and perform the experiments of coupled multilevel
and resonator systems and can be applied in the case of transmon or Xmon qudits having similar anharmonicity
to the present phase device.This work was supported by the Ministry of Science and Technology of China (Grants No. 2014CB921202, No. 2015CB921104, and No. 2016YFA0300601),the National Natural Science Foundation of China (Grants No. 91321208 and No. 11674380)the Key Research Program of the Chinese Academy of Sciences (Grant No. XDPB08-3)S.H. acknowledges support by the US NSF (PHY-1314861)
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