78 research outputs found
A Survey of Research Progress and Development Tendency of Attribute-Based Encryption
With the development of cryptography, the attribute-based encryption (ABE) draws widespread attention of the researchers in recent years. The ABE scheme, which belongs to the public key encryption mechanism, takes attributes as public key and associates them with the ciphertext or the user’s secret key. It is an efficient way to solve open problems in access control scenarios, for example, how to provide data confidentiality and expressive access control at the same time. In this paper, we survey the basic ABE scheme and its two variants: the key-policy ABE (KP-ABE) scheme and the ciphertext-policy ABE (CP-ABE) scheme. We also pay attention to other researches relating to the ABE schemes, including multiauthority, user/attribute revocation, accountability, and proxy reencryption, with an extensive comparison of their functionality and performance. Finally, possible future works and some conclusions are pointed out
A Multistep Extending Truncation Method towards Model Construction of Infinite-State Markov Chains
The model checking of Infinite-State Continuous Time Markov Chains will inevitably encounter the state explosion problem when constructing the CTMCs model; our method is to get a truncated model of the infinite one; to get a sufficient truncated model to meet the model checking of Continuous Stochastic Logic based system properties, we propose a multistep extending advanced truncation method towards model construction of CTMCs and implement it in the INFAMY model checker; the experiment results show that our method is effective
Uncertainty-guided Boundary Learning for Imbalanced Social Event Detection
Real-world social events typically exhibit a severe class-imbalance
distribution, which makes the trained detection model encounter a serious
generalization challenge. Most studies solve this problem from the frequency
perspective and emphasize the representation or classifier learning for tail
classes. While in our observation, compared to the rarity of classes, the
calibrated uncertainty estimated from well-trained evidential deep learning
networks better reflects model performance. To this end, we propose a novel
uncertainty-guided class imbalance learning framework - UCL, and its
variant - UCL-EC, for imbalanced social event detection tasks. We aim
to improve the overall model performance by enhancing model generalization to
those uncertain classes. Considering performance degradation usually comes from
misclassifying samples as their confusing neighboring classes, we focus on
boundary learning in latent space and classifier learning with high-quality
uncertainty estimation. First, we design a novel uncertainty-guided contrastive
learning loss, namely UCL and its variant - UCL-EC, to manipulate
distinguishable representation distribution for imbalanced data. During
training, they force all classes, especially uncertain ones, to adaptively
adjust a clear separable boundary in the feature space. Second, to obtain more
robust and accurate class uncertainty, we combine the results of multi-view
evidential classifiers via the Dempster-Shafer theory under the supervision of
an additional calibration method. We conduct experiments on three severely
imbalanced social event datasets including Events2012\_100, Events2018\_100,
and CrisisLexT\_7. Our model significantly improves social event representation
and classification tasks in almost all classes, especially those uncertain
ones.Comment: Accepted by TKDE 202
High temperature superconductivity of quaternary hydrides XM3Be4H32 (X, M = Ca, Sr, Ba, Y, La, Ac, Th) under moderate pressure
The compressed hydrogen-rich compounds have received extensive attention as
promising candidates for room temperature superconductivity, however, the high
pressure required to stabilize such materials hinders their wide practical
application. In order to search for potential superconducting hydrides that are
stable at low pressures, we have investigated the crystal structures and
properties of quaternary hydrides, XM3Be4H32 (X, M = Ca, Sr, Ba, Y, La, Ac, Th)
based on the first-principles calculations. We identified nine dynamically
stable compounds at moderate pressure of 20 GPa. Strikingly, their
superconducting transition temperatures are much higher than that of liquid
nitrogen, especially CaTh3Be4H32 (124 K at 5 GPa), ThLa3Be4H32(134 K at 10
GPa), LaAc3Be4H32 (135 K at 20 GPa) and AcLa3Be4H32 (153 K at 20 GPa) exhibit
outstanding superconductivity at mild pressures. Metal atoms acting as
pre-compressors donate abundant electrons to hydrogen, weakening the H-H
covalent bond and thus facilitating the metallization of the hydrogen
sublattice. At the same time, the appropriate combination of metal elements
with different ionic radius and electronegativity can effectively tune the
electronic structure near the Fermi level and improve the superconductivity.
These findings fully reveal the great promise of hosting high-temperature
superconductivity of quaternary hydrides at moderate pressures and will further
promote related exploration.Comment: 14 pages, 6 figure
Anti-oxidative effects of the biennial flower of Panax notoginseng against H2O2-induced cytotoxicity in cultured PC12 cells
<p>Abstract</p> <p>Background</p> <p><it>Radix notoginseng </it>is used in Chinese medicine to improve blood circulation and clotting; however, the pharmacological activities of other parts of <it>Panax notoginseng </it>have yet to be explored. The present study reports the anti-oxidative effects of various parts of <it>Panax notoginseng</it>.</p> <p>Methods</p> <p>Various parts of <it>Panax notoginseng</it>, including the biennial flower, stem-leaf, root-rhizome, fiber root and sideslip, were used to prepare extracts and analyzed for their anti-oxidation effects, namely suppressing xanthine oxidase activity, H<sub>2</sub>O<sub>2</sub>-induced cytotoxicity and H<sub>2</sub>O<sub>2</sub>-induced ROS formation.</p> <p>Results</p> <p>Among various parts of the herb (biennial flower, stem-leaf, root-rhizome, fiber root and sideslip), the water extract of the biennial flower showed the strongest effects in (i) inhibiting the enzymatic activity of xanthine oxidase and (ii) protecting neuronal PC12 cells against H<sub>2</sub>O<sub>2</sub>-induced cytotoxicity. Only the water extracts demonstrated such anti-oxidative effects while the ethanol extracts did not exert significant effects in suppressing xanthine oxidase and H<sub>2</sub>O<sub>2</sub>-induced neuronal cytotoxicity.</p> <p>Conclusions</p> <p>The present study demonstrates the biennial flower of <it>Panax notoginseng </it>to have neuroprotection effect on cultured neurons and the underlying protection mechanism may involve anti-oxidation.</p
mTOR Kinase Inhibition Effectively Decreases Progression of a Subset of Neuroendocrine Tumors that Progress on Rapalog Therapy and Delays Cardiac Impairment
Inhibition of mTOR signaling using the rapalog everolimus is an FDA-approved targeted therapy for patients with lung and gastroenteropancreatic neuroendocrine tumors (NET). However, patients eventually progress on treatment, highlighting the need for additional therapies. We focused on pancreatic NETs (pNET) and reasoned that treatment of these tumors upon progression on rapalog therapy, with an mTOR kinase inhibitor (mTORKi), such as CC-223, could overcome a number of resistance mechanisms in tumors and delay cardiac carcinoid disease. We performed preclinical studies using human pNET cells in vitro and injected them subcutaneously or orthotopically to determine tumor progression and cardiac function in mice treated with either rapamycin alone or switched to CC-223 upon progression. Detailed signaling and RNA sequencing analyses were performed on tumors that were sensitive or progressed on mTOR treatment. Approximately 57% of mice bearing pNET tumors that progressed on rapalog therapy showed a significant decrease in tumor volume upon a switch to CC-223. Moreover, mice treated with an mTORKi exhibited decreased cardiac dilation and thickening of heart valves than those treated with placebo or rapamycin alone. In conclusion, in the majority of pNETs that progress on rapalogs, it is possible to reduce disease progression using an mTORKi, such as CC-223. Moreover, CC-223 had an additional transient cardiac benefit on valvular fibrosis compared with placebo- or rapalog-treated mice. These results provide the preclinical rationale to further develop mTORKi clinically upon progression on rapalog therapy and to further test their long-term cardioprotective benefit in those NET patients prone to carcinoid syndrome
THEORETICAL MODELING AND TEST SIMULATION RESEARCH OF DOUBLE-LAYER VIBRATION ISOLATION SYSTEM
The theoretical model of double-layer vibration isolation system based on the icebox compressor was built through the four-point parameter method,and got the force transportation-rate pattern,found the finite element simulation model of double-layer vibration isolation,obtained the main mode of the system through mode analysis and the force transportation-rate through dynamic reaction analysis. The force transportation-rate results through theoretical model and finite simulation method and test were compared and analyzed,the results show,the natural frequencies obtained from the theoretical model and simulation model are basically same,the force transportation-rate has the same trend on the whole,the theoretical results and simulated results accord well with the test results in the low frequency between 0 to 150 Hz,when the frequency exceeds 150 Hz,there are some differences between theoretical results,simulation results and test results to some extent
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