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Transient execution attacks, also called speculative execution attacks, have drawn much interest as they exploit the transient execution of instructions, e.g., during branch prediction, to leak data. Transient execution is fundamental to modern computer architectures, yet poses a security risk as has been demonstrated. Since the first disclosure of Spectre and Meltdown attacks in January 2018, a number of new attack types or variants of the attacks have been presented. These attacks havearXiv:2005.13435v2 fatcat:fuigp3ipqnbghlf5dch2r6zp5u
more »... ed computer architects to rethink the design of processors and propose hardware defenses. This paper summarizes the components and the phases of the transient execution attacks. Each of the components is further discussed and categorized. A set of metrics is proposed for each component to evaluate the feasibility of an attack. Moreover, the data that can be leaked in the attacks are summarized. Further, the existing attacks are compared, and the limitations of these attacks are discussed based on the proposed metrics. In the end, existing mitigations at the micro-architecture level from literature are discussed.
The Least-Recently Used cache replacement policy and its variants are widely deployed in modern processors. This paper shows for the first time in detail that the LRU states of caches can be used to leak information: any access to a cache by a sender will modify the LRU state, and the receiver is able to observe this through a timing measurement. This paper presents LRU timing-based channels both when the sender and the receiver have shared memory, e.g., shared library data pages, and when theyarXiv:1905.08348v2 fatcat:c2l7njmzs5bthf7zvpzoyhzwgq
more »... are separate processes without shared memory. In addition, the new LRU timing-based channels are demonstrated on both Intel and AMD processors in scenarios where the sender and the receiver are sharing the cache in both hyper-threaded setting and time-sliced setting. The transmission rate of the LRU channels can be up to 600Kbps per cache set in the hyper-threaded setting. Different from the majority of existing cache channels which require the sender to trigger cache misses, the new LRU channels work with the sender only having cache hits, making the channel faster and more stealthy. This paper also demonstrates that the new LRU channels can be used in transient execution attacks, e.g., Spectre. Further, this paper shows that the LRU channels pose threats to existing secure cache designs, and this work demonstrates the LRU channels affect the secure PL cache. The paper finishes by discussing and evaluating possible defenses.
AbstractExosomes are lipid bilayer membrane vesicles and are emerging as competent nanocarriers for drug delivery. The clinical translation of exosomes faces many challenges such as massive production, standard isolation, drug loading, stability and quality control. In recent years, artificial exosomes are emerging based on nanobiotechnology to overcome the limitations of natural exosomes. Major types of artificial exosomes include 'nanovesicles (NVs)', 'exosome-mimetic (EM)' and 'hybriddoi:10.1186/s12951-021-00986-2 pmid:34384440 pmcid:PMC8359033 fatcat:qcb42qfgybdfrlt3gq5nrd2lvi
more »... s (HEs)', which are obtained by top-down, bottom-up and biohybrid strategies, respectively. Artificial exosomes are powerful alternatives to natural exosomes for drug delivery. Here, we outline recent advances in artificial exosomes through nanobiotechnology and discuss their strengths, limitations and future perspectives. The development of artificial exosomes holds great values for translational nanomedicine.
Syngas to ethanol, consisting of dimethyl ether (DME) carbonylation to methyl acetate (MA) over zeolites and MA hydrogenation to ethanol on copper catalyst, has been developed in recent years. DME carbonylation over zeolites, a key step in this new process, has attracted increasing attention due to the high reaction efficiency and promising industrial application. In recent years, continuous effort s have been made on improving the activity and stability of the zeolites. From a mechanisticdoi:10.1016/j.jechem.2019.04.015 fatcat:6kfxtm4hefevnhojofre3d7tza
more »... of view, DME carbonylation to MA, involving the formation of C -C bond, is achieved via the Koch-type CO insertion into DME within the 8-member ring (8-MR) pores of zeolites, typically HMOR and HZSM-35. The unique geometric configuration of the 8-MR pore endowed the formation of the key intermediate (acetyl, CH 3 CO * ), possibly by a spatial confinement of the transition state during CO insertion into the surface O -CH 3 group. This review article summarizes the main progress on zeolite-catalyzed DME carbonylation, including reaction kinetics and mechanism, theoretical calculations, and experimental strategies developed for populating acid sites and engineering pore structure of the zeolites in order to enhance the overall performance.
Timing-based side or covert channels in processor caches continue to present a threat to computer systems, and they are the key to many of the recent Spectre and Meltdown attacks. Based on improvements to an existing three-step model for cache timing-based attacks, this work presents 88 Strong types of theoretical timing-based vulnerabilities in processor caches. To understand and evaluate all possible types of vulnerabilities in processor caches, this work further presents and implements a newarXiv:1911.08619v1 fatcat:h3lbynlumzbbtg22fisw6f7444
more »... benchmark suite which can be used to test to which types of cache timing-based attacks a given processor or cache design is vulnerable. In total, there are 1094 automatically-generated test programs which cover the 88 theoretical vulnerabilities. The benchmark suite generates the Cache Timing Vulnerability Score which can be used to evaluate how vulnerable a specific cache implementation is to different attacks. A smaller Cache Timing Vulnerability Score means the design is more secure, and the scores among different machines can be easily compared. Evaluation is conducted on commodity Intel and AMD processors and shows the differences in processor implementations can result in different types of attacks that they are vulnerable to. Beyond testing commodity processors, the benchmarks and the Cache Timing Vulnerability Score can be used to help designers of new secure processor caches evaluate their design's susceptibility to cache timing-based attacks.
. * Xiang Li is the corresponding author and the work is done while Wenjie Qin is doing research intern at Xiaomi AI Lab Clean Input 建一所小学 Output of NMT build a primary school Noisy Input 建议所小学 Output ...arXiv:2012.08396v1 fatcat:proiohxh7ja3rirl2vcuek3pxe
The precast shear wall behavior in the serviceability and ultimate limit states depends on the shear and shear-flexural behavior of the joints between the precast components or between the precast component and footing. This study presents a series of tests on the shear strength of joints, which were applied to the interface of precast shear walls. The tested parameters included the joint types, the numbers of shear keys, the existence of high strength steel bars inserted at the joints, and thedoi:10.3390/ma13071726 pmid:32272664 fatcat:vysg66cq2jdwxjb2o7tfh62mgu
more »... levels of confining stress. The shear capacity, stiffness, and shear transfer mechanisms of these joints were investigated. It could be concluded that the epoxied and high strength reinforcing joints had consistently higher shear strength than that of dry and plain joints. For the specimens with an inclined angle at the end of the keys of less than 60 degrees, the width of the dry joint opening may be excessively large, resulting in large shear slip and the key not shearing-off under confining stress of less than 1.0 MPa. The tested results were compared with AASHTO and other design criteria. Several formulas regarding the joint shear capacities were also proposed according to the specifications and the tested results.
Zhiyuan Cai, Huanhui Cao, Wenjie Lu, and Hao Xiong are with the School of Mechanical Engineering and Automation, Harbin Institute of Technology Shenzhen, Shenzhen, China. 2 Lin Zhang is with the Department ...arXiv:2103.12553v1 fatcat:dqowkp4kojcntemtm5hsyy46rq
Aflatoxins - Detection, Measurement and Control
How to reference In order to correctly reference this scholarly work, feel free to copy and paste the following: Huili Zhang, Jianwei He, Bing Li, Hui Xiong, Wenjie Xu and Xianjun Meng (2011) . ...doi:10.5772/23282 fatcat:wcfbjtfeq5exzaxc4wftio45dq
Image captioning is the task of generating textual descriptions of images. In order to obtain a better image representation, attention mechanisms have been widely adopted in image captioning. However, in existing models with detection-based attention, the rectangular attention regions are not fine-grained, as they contain irrelevant regions (e.g., background or overlapped regions) around the object, making the model generate inaccurate captions. To address this issue, we propose panopticdoi:10.3390/app10010391 fatcat:d7q7fqpxefbsvn4fs3u4ct47tq
more »... ation-based attention that performs attention at a mask-level (i.e., the shape of the main part of an instance). Our approach extracts feature vectors from the corresponding segmentation regions, which is more fine-grained than current attention mechanisms. Moreover, in order to process features of different classes independently, we propose a dual-attention module which is generic and can be applied to other frameworks. Experimental results showed that our model could recognize the overlapped objects and understand the scene better. Our approach achieved competitive performance against state-of-the-art methods. We made our code available.
Cardiovascular diseases have become one of the most prevalent threats to human health throughout the world. As a noninvasive assistant diagnostic tool, the heart sound detection techniques play an important role in the prediction of cardiovascular diseases. In this paper, the latest development of the computer-aided heart sound detection techniques over the last five years has been reviewed. There are mainly the following aspects: the theories of heart sounds and the relationship between heartdoi:10.1155/2020/5846191 pmid:32420352 pmcid:PMC7201685 fatcat:iyzetxo2cvhw3o3jqizoynhsi4
more »... ounds and cardiovascular diseases; the key technologies used in the processing and analysis of heart sound signals, including denoising, segmentation, feature extraction and classification; with emphasis, the applications of deep learning algorithm in heart sound processing. In the end, some areas for future research in computer-aided heart sound detection techniques are explored, hoping to provide reference to the prediction of cardiovascular diseases.
Acoustic localization for a moving source plays a key role in engineering applications, such as wildlife conservation and health protection. Acoustic detection methods provide an alternative to traditional radar and infrared detection methods. Here, an acoustic locating method of array signal processing based on intersecting azimuth lines of two arrays is introduced. The locating algorithm and the precision simulation of a single array shows that such a single array has good azimuth precisiondoi:10.3390/app8081281 fatcat:mgfzhtq2v5dzfdukkcv6ib2iuy
more »... d bad range estimation. Once another array of the same type is added, the moving acoustic source can be located precisely by intersecting azimuth lines. A low-speed vehicle is used as the simulated moving source for the locating experiments. The length selection of short correlation and moving path compensation are studied in the experiments. All results show that the proposed novel method locates the moving sound source with high precision (<5%), while requiring fewer instruments than current methods.
Then, the Jaccard index for the two DRAM PUF responses is defined as: J (F 1 , F 2 ) = |F 1 ∩ F 2 | |F 1 ∪ F 2 | (1) As shown by Xiong et al. ...doi:10.1145/3373087.3375322 dblp:conf/fpga/Tian0GRS20 fatcat:m5ki5f76drhrtkmfrzfqcrexdy
Recently, two-dimensional MXenes and MXene-based nanocomposites have become the most important electrode materials because of their unique physical and chemical characteristics. As the electrode of a lithium-ion capacitor, MXenes have exhibited metallic conductivity and plastic layer structure that provide more chemically active interfaces and shortened ion-diffusion lengths, and thus the unbalanced ion kinetics between the anode and cathode can be effectively alleviated. In order to furtherdoi:10.1021/acsomega.9b03662 pmid:31956753 pmcid:PMC6963900 fatcat:wo33ucoro5h3towmdnc4edbkdy
more »... rove the electrochemical performance of MXenes, the composition, morphology and texture, surface chemistry, and structural configuration of MXenes are extensively investigated. In this mini-review, some recent research and progress of MXenes and MXene-based nanocomposites in lithium-ion capacitors are summarized, which focus on their nanostructure designs and chemical preparation methods, such as prepillaring MXenes, delaminated MXenes, and MXene-based hybrids. Finally, some future perspectives and critical challenges of MXene-based material for lithium-ion capacitor application are also presented and briefly discussed.
Background Early diagnostic indicators and the identification of possible progression to severe or critical COVID-19 in children are unknown. To investigate the immune characteristics of early SARS-CoV-2 infection in children and possible key prognostic factors for early identification of critical COVID-19, a retrospective study including 121 children with COVID-19 was conducted. Peripheral blood lymphocyte subset counts, T cell-derived cytokine concentrations, inflammatory factordoi:10.1186/s12887-021-02561-y pmid:33865340 fatcat:bxajurfmovgytchp5wvobatnri
more »... , and routine blood counts were analyzed statistically at the initial presentation. Results The T lymphocyte subset and natural killer cell counts decreased with increasing disease severity. Group III (critical cases) had a higher Th/Tc ratio than groups I and II (common and severe cases); group I had a higher B cell count than groups II and III. IL-6, IL-10, IFN-γ, SAA, and procalcitonin levels increased with increasing disease severity. Hemoglobin concentration, and RBC and eosinophil counts decreased with increasing disease severity. Groups II and III had significantly lower lymphocyte counts than group I. T, Th, Tc, IL-6, IL-10, RBC, and hemoglobin had relatively high contribution and area under the curve values. Conclusions Decreased T, Th, Tc, RBC, hemoglobin and increased IL-6 and IL-10 in early SARS-CoV-2 infection in children are valuable indices for early diagnosis of severe disease. The significantly reduced Th and Tc cells and significantly increased IL-6, IL-10, ferritin, procalcitonin, and SAA at this stage in children with critical COVID-19 may be closely associated with the systemic cytokine storm caused by immune dysregulation.
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