A Dual Stealthy Backdoor: From Both Spatial and Frequency Perspectives

Backdoor attacks pose serious security threats to deep neural networks (DNNs). Backdoored models make arbitrarily (targeted) incorrect predictions on inputs embedded with well-designed triggers while behaving normally on clean inputs. Many works have explored the invisibility of backdoor triggers to improve attack stealthiness. However, most of them only consider the invisibility in the spatial domain without explicitly accounting for the generation of invisible triggers in the frequency domain, making the generated poisoned images be easily detected by recent defense methods. To address this issue, in this paper, we propose a DUal stealthy BAckdoor attack method named DUBA, which simultaneously considers the invisibility of triggers in both the spatial and frequency domains, to achieve desirable attack performance, while ensuring strong stealthiness. Specifically, we first use Discrete Wavelet Transform to embed the high-frequency information of the trigger image into the clean image to ensure attack effectiveness. Then, to attain strong stealthiness, we incorporate Fourier Transform and Discrete Cosine Transform to mix the poisoned image and clean image in the frequency domain. Moreover, the proposed DUBA adopts a novel attack strategy, in which the model is trained with weak triggers and attacked with strong triggers to further enhance the attack performance and stealthiness. We extensively evaluate DUBA against popular image classifiers on four datasets. The results demonstrate that it significantly outperforms the state-of-the-art backdoor attacks in terms of the attack success rate and stealthinessComment: 10 pages, 7 figures. Submit to ACM MM 202

Prototype Active Silicon Sensor in 150 nm HR-CMOS Technology for ATLAS Inner Detector Upgrade

The LHC Phase-II upgrade will lead to a significant increase in luminosity, which in turn will bring new challenges for the operation of inner tracking detectors. A possible solution is to use active silicon sensors, taking advantage of commercial CMOS technologies. Currently ATLAS R&D programme is qualifying a few commercial technologies in terms of suitability for this task. In this paper a prototype designed in one of them (LFoundry 150 nm process) will be discussed. The chip architecture will be described, including different pixel types incorporated into the design, followed by simulation and measurement results.Comment: 9 pages, 9 figures, TWEPP 2015 Conference, submitted to JINS

Serum osteocalcin and urinary free deoxypyridinoline as potential risk factors in predicting the prevalence of bone trauma among the post-menopausal Chinese women

This study was designed to understand whether the post-menopausal Chinese women (n=175) receiving tablet containing vitamin D (500 IU) and calcium (500 mg) had lower incidence of bone fracture compared to the post-menopausal Chinese women ((n=175) receiving a diet rich in calcium, vitamin D, and protein  (milk, cheese, and yogurt, soybeans, spinach, fish including fatty fish, cheese, egg). This study assessed whether the levels of serum osteocalcin and urinary free deoxypyridinoline could be used as predictors of early bone trauma during post-menopausal period. After randomization, subjects were followed-up for up to 3 years to capture required data. The results suggested that therapeutic intervention (vitamin D and calcium) does not predict bone fracture among the post-menopausal Chinese women. However, correlation analysis revealed that the decreased level of serum osteocalcin and urinary free deoxypyridinoline were associated with higher incidence of fracture. The results suggest that the low level of serum osteocalcin and urinary free deoxypyridinoline cause increase susceptibility of fracture among the post-menopausal Chinese women

Simulation study of BESIII with stitched CMOS pixel detector using ACTS

Reconstruction of tracks of charged particles with high precision is very crucial for HEP experiments to achieve their physics goals. As the tracking detector of BESIII experiment, the BESIII drift chamber has suffered from aging effects resulting in degraded tracking performance after operation for about 15 years. To preserve and enhance the tracking performance of BESIII, one of the proposals is to add one layer of thin CMOS pixel sensor in cylindrical shape based on the state-of-the-art stitching technology, between the beam pipe and the drift chamber. The improvement of tracking performance of BESIII with such an additional pixel detector compared to that with only the existing drift chamber is studied using the modern common tracking software ACTS, which provides a set of detector-agnostic and highly performant tracking algorithms that have demonstrated promising performance for a few high energy physics and nuclear physics experiments

CYP2C19 genotype and platelet aggregation test-guided dual antiplatelet therapy after off-pump coronary artery bypass grafting: A retrospective cohort study

BackgroundDual antiplatelet therapy (DAPT) is recommended in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB). Clopidogrel is less effective among patients with loss-of-function (LoF) of CYP2C19 alleles, while ticagrelor has direct effects on P2Y12 receptor. Whether a CYP2C19 genotype plus platelet aggregation test (PAgT)-guided DAPT after CABG could improve clinical outcomes remain uncertain.Materials and methodsFrom August 2019 to December 2020, 1,134 consecutive patients who underwent OPCAB received DAPT for 1 year after surgery in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine. According to the actual treatment they received in real-world, 382 (33.7%) of them received a traditional DAPT: aspirin 100 mg qd + clopidogrel 75 mg qd, no matter the CYP2C19 genotype and response in platelet aggregation test (PAgT). The other 752 (66.3%) patients received an individual DAPT based on CYP2C19 genotype and PAgT: aspirin 100 mg qd + clopidogrel 75 mg qd if CYP2C19 was extensive metabolizer, or moderate metabolizer but normal response in PAgT; aspirin 100 mg qd + ticagrelor 90 mg bid if CYP2C19 was poor metabolizer, or moderate metabolizer but no or low response in PAgT. One-year follow-up was achieved for all patients. The primary outcome was major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, and stroke. The safety outcome was thrombolysis in myocardial infarction (TIMI) criteria major bleeding.ResultsCompared with the traditional DAPT group, the risk of MACE in the individual DAPT group was significantly lower (5.5 vs. 9.2%, HR 0.583; 95% CI, 0.371–0.915; P = 0.019), mainly due to the decreased risk of MI (1.7 vs. 4.2%, HR 0.407; 95% CI, 0.196–0.846; P = 0.016). The risk of TIMI major bleeding events was similar between the two groups (5.3 vs. 6.0%, RR 0.883; 95% CI, 0.537–1.453; P = 0.626).ConclusionFor patients who underwent OPCAB, individual DAPT (CYP2C19 genotype plus PAgT-guided strategy) was associated with a lower risk of MACE and a similar risk of major bleeding