17 research outputs found
Certifiable Black-Box Attack: Ensuring Provably Successful Attack for Adversarial Examples
Black-box adversarial attacks have shown strong potential to subvert machine
learning models. Existing black-box adversarial attacks craft the adversarial
examples by iteratively querying the target model and/or leveraging the
transferability of a local surrogate model. Whether such attack can succeed
remains unknown to the adversary when empirically designing the attack. In this
paper, to our best knowledge, we take the first step to study a new paradigm of
adversarial attacks -- certifiable black-box attack that can guarantee the
attack success rate of the crafted adversarial examples. Specifically, we
revise the randomized smoothing to establish novel theories for ensuring the
attack success rate of the adversarial examples. To craft the adversarial
examples with the certifiable attack success rate (CASR) guarantee, we design
several novel techniques, including a randomized query method to query the
target model, an initialization method with smoothed self-supervised
perturbation to derive certifiable adversarial examples, and a geometric
shifting method to reduce the perturbation size of the certifiable adversarial
examples for better imperceptibility. We have comprehensively evaluated the
performance of the certifiable black-box attack on CIFAR10 and ImageNet
datasets against different levels of defenses. Both theoretical and
experimental results have validated the effectiveness of the proposed
certifiable attack
L-SRR: Local Differential Privacy for Location-Based Services with Staircase Randomized Response
Location-based services (LBS) have been significantly developed and widely
deployed in mobile devices. It is also well-known that LBS applications may
result in severe privacy concerns by collecting sensitive locations. A strong
privacy model ''local differential privacy'' (LDP) has been recently deployed
in many different applications (e.g., Google RAPPOR, iOS, and Microsoft
Telemetry) but not effective for LBS applications due to the low utility of
existing LDP mechanisms. To address such deficiency, we propose the first LDP
framework for a variety of location-based services (namely ''L-SRR''), which
privately collects and analyzes user locations with high utility. Specifically,
we design a novel randomization mechanism ''Staircase Randomized Response''
(SRR) and extend the empirical estimation to significantly boost the utility
for SRR in different LBS applications (e.g., traffic density estimation, and
k-nearest neighbors). We have conducted extensive experiments on four real LBS
datasets by benchmarking with other LDP schemes in practical applications. The
experimental results demonstrate that L-SRR significantly outperforms them.Comment: accepted to CCS'22; full versio
Circulating Mucosal-Associated Invariant T Cells in a Large Cohort of Healthy Chinese Individuals From Newborn to Elderly
Mucosal-associated invariant T (MAIT) cells, which are enriched in human blood and express a semi-invariant TCR chain, play important roles in conditions such as infectious diseases and cancer. The influence of age on levels and functional characteristics of circulating MAIT cells have not been fully addressed. Here we have collected blood samples from a large cohort of healthy Chinese individuals from newborn (cord blood) to the elderly and assessed the levels of circulating MAIT cells as well as their phenotype, activation and apoptosis status, and cytokine expression profiles after in vitro stimulation. We found that the frequencies of circulating MAIT cells gradually increased in blood from newborns as they progressed into adulthood (20–40 years old) but then decreased during further progression toward old age (>60 years old). The lowered numbers of circulating MAIT cells in the elderly was correlated with a gradual increase of apoptosis. A majority of circulating MAIT cells expressed the chemokine receptors CCR5 and CCR6, and most also expressed CD8 and CD45RO. Few expressed CD69 in cord blood, but the frequency increased with age. Upon in vitro activation with PMA plus ionomycin or IL12 plus IL18, fewer MAIT cells isolated from the young adult group expressed IFN-γ, IL17A and Granzyme B then cells from other age groups while the proportion of cells that expressed TNF-α was similar. Taken together, our data provide information for guiding the assessment of normal levels and phenotypes of MAIT cells at different ages in healthy individuals and patients
numericalsimulationandexperimentalverificationofgasbubbleemittingdownwardsintowaterormagneticfluid
应用数值与实验的方法分析了气泡向下鼓入水和磁性液体的过程,通过数学模型应用PLIC-VOF方法仿真重现了气泡的形成与破裂机理,通过数值模拟获得了气泡的形状与生长周期,用CCD摄像头完成实验测量,实验与模拟达到了数值上的吻合
向下鼓气泡进入水或磁性液体的数值模拟与实验验证
应用数值与实验的方法分析了气泡向下鼓入水和磁性液体的过程,通过数学模型应用PLIC-VOF方法仿真重现了气泡的形成与破裂机理,通过数值模拟获得了气泡的形状与生长周期,用CCD摄像头完成实验测量,实验与模拟达到了数值上的吻合
向下鼓气泡进入水或磁性液体的数值模拟与实验验证
应用数值与实验的方法分析了气泡向下鼓入水和磁性液体的过程,通过数学模型应用PLIC-VOF方法仿真重现了气泡的形成与破裂机理,通过数值模拟获得了气泡的形状与生长周期,用CCD摄像头完成实验测量,实验与模拟达到了数值上的吻合
Dendroclimatological Analysis of Chinese Fir Using a Long-Term Provenance Trial in Southern China
The Chinese fir, Cunninghamia lanceolata (Lamb.) Hook, is an essential fast-growing timber species that is widely distributed in southern China, producing timber with high economic value. Understanding the climate sensitivity of the tree species and its intra-specific variation would help us to estimate the potential climatic adaptation of the Chinese fir. Consequently, we developed radial growth (tree-ring, earlywood and latewood width) and wood density (earlywood, latewood, minimum and maximum density) chronologies for the period 1981–2013 to evaluate whether Chinese fir provenances varied in their tree-ring characteristics and the strength of their responses to seasonal and monthly climate variables. The results showed that more climatic information was obtainable from the trees’ radial growth than from their wood densities. Moreover, the wood density variables provided additional information about seasonal precipitation, which could not be found in tree-ring widths. Specifically, radial growth was highly sensitive to spring and fall temperature, whereas the wood density (particularly that of maximum density) was mainly limited by spring precipitation. Importantly, each tree-ring chronology of Chinese fir provenances varied in the intensity of its response to climate variables, reflecting population acclimation via genetic adaptation or plasticity to local conditions. By providing a theoretical basis for the climate–growth relationships of Chinese fir provenance within a subtropical climate, one can evaluate future climate change impacts on forests and the feedback of forest systems
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Mutant p53 regulates enhancer-associated H3K4 monomethylation through interactions with the methyltransferase MLL4.
Monomethylation of histone H3 lysine 4 (H3K4me1) is enriched at enhancers that are primed for activation and the levels of this histone mark are frequently altered in various human cancers. Yet, how alterations in H3K4me1 are established and the consequences of these epigenetic changes in tumorigenesis are not well understood. Using ChIP-Seq in human colon cancer cells, we demonstrate that mutant p53 depletion results in decreased H3K4me1 levels at active enhancers that reveal a striking colocalization of mutant p53 and the H3K4 monomethyltransferase MLL4 following chronic tumor necrosis factor alpha (TNFα) signaling. We further reveal that mutant p53 forms physiological associations and direct interactions with MLL4 and promotes the enhancer binding of MLL4, which is required for TNFα-inducible H3K4me1 and histone H3 lysine 27 acetylation (H3K27ac) levels, enhancer-derived transcript (eRNA) synthesis, and mutant p53-dependent target gene activation. Complementary in vitro studies with recombinant chromatin and purified proteins demonstrate that binding of the MLL3/4 complex and H3K4me1 deposition is enhanced by mutant p53 and p300-mediated acetylation, which in turn reflects a MLL3/4-dependent enhancement of mutant p53 and p300-dependent transcriptional activation. Collectively, our findings establish a mechanism in which mutant p53 cooperates with MLL4 to regulate aberrant enhancer activity and tumor-promoting gene expression in response to chronic immune signaling
An investigation on the relationship between the stability of lithium anode and lithium nitrate in electrolyte
Understanding the relationship between lithium anode and electrolyte is important to develop a more compatible lithium/electrolyte system for stable and safe cycling of lithium-metal based batteries. However, to date, there has not been any work to quantify the effects of electrolyte on the performance of electrode due to the complexity. Herein, we quantify the relationship between an electrolyte additive, LiNO3, and the stability of lithium anode. It is found that, with increasing the amount of LiNO3, the cyclability of lithium anode rises linearly and the risk of dendrite-induced short circuits can be reduced. Low Coulombic efficiency (CE) and short circuits tend to occur in tandem. LiNO3 is found to be continuously consumed upon electrochemical cycling, which leads to a low CE and a high risk of short circuits.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Published versio