Capability Memory Protection for Embedded Systems

This dissertation explores the use of capability security hardware and software in real-time and latency-sensitive embedded systems, to address existing memory safety and task isolation problems as well as providing new means to design a secure and scalable real-time system. In addition, this dissertation looks into how practical and high-performance temporal memory safety can be achieved under a capability architecture. State-of-the-art memory protection schemes for embedded systems typically present limited and inflexible solutions to memory protection and isolation, and fail to scale as embedded devices become more capable and ubiquitous. I investigate whether a capability architecture is able to provide new angles to address memory safety issues in an embedded scenario. Previous CHERI capability research focuses on 64-bit architectures in UNIX operating systems, which does not translate to typical 32-bit embedded processors with low-latency and real-time requirements. I propose and implement the CHERI CC-64 encoding and the CHERI-64 coprocessor to construct a feasible capability-enabled 32-bit CPU. In addition, I implement a real-time kernel for embedded systems atop CHERI-64. On this hardware and software platform, I focus on exploring scalable task isolation and fine-grained memory protection enabled by capabilities in a single flat physical address space, which are otherwise difficult or impossible to achieve via state-of-the-art approaches. Later, I present the evaluation of the hardware implementation and the software run-time overhead and real-time performance. Even with capability support, CHERI-64 as well as other CHERI processors still expose major attack surfaces through temporal vulnerabilities like use-after-free. A naive approach that sweeps memory to invalidate stale capabilities is inefficient and incurs significant cycle overhead and DRAM traffic. To make sweeping revocation feasible, I introduce new architectural mechanisms and micro-architectural optimisations to substantially reduce the cost of memory sweeping and capability revocation. Another factor of the cost is the frequency of memory sweeping. I explore tradeoffs of memory allocator designs that use quarantine buffers and shadow space tags to prevent frequent unnecessary sweeping. The evaluation shows that the optimisations and new allocator designs reduce the cost of capability sweeping revocation by orders of magnitude, making it already practical for most applications to adopt temporal safety under CHERI.CSC Cambridge Scholarshi

A construct with fluorescent indicators for conditional expression of miRNA

<p>Abstract</p> <p>Background</p> <p>Transgenic RNAi holds promise as a simple, low-cost, and fast method for reverse genetics in mammals. It may be particularly useful for producing animal models for hypomorphic gene function. Inducible RNAi that permits spatially and temporally controllable gene silencing in vivo will enhance the power of transgenic RNAi approach. Furthermore, because microRNA (miRNA) targeting specific genes can be expressed simultaneously with protein coding genes, incorporation of fluorescent marker proteins can simplify the screening and analysis of transgenic RNAi animals.</p> <p>Results</p> <p>We sought to optimally express a miRNA simultaneously with a fluorescent marker. We compared two construct designs. One expressed a red fluorescent protein (RFP) and a miRNA placed in its 3' untranslated region (UTR). The other expressed the same RFP and miRNA, but the precursor miRNA (pre-miRNA) coding sequence was placed in an intron that was inserted into the 3'-UTR. We found that the two constructs expressed comparable levels of miRNA. However, the intron-containing construct expressed a significantly higher level of RFP than the intron-less construct. Further experiments indicate that the 3'-UTR intron enhances RFP expression by its intrinsic gene-expression-enhancing activity and by eliminating the inhibitory effect of the pre-miRNA on the expression of RFP. Based on these findings, we incorporated the intron-embedded pre-miRNA design into a conditional expression construct that employed the Cre-loxP system. This construct initially expressed EGFP gene, which was flanked by loxP sites. After exposure to Cre recombinase, the transgene stopped EGFP expression and began expression of RFP and a miRNA, which silenced the expression of specific cellular genes.</p> <p>Conclusion</p> <p>We have designed and tested a conditional miRNA-expression construct and showed that this construct expresses both the marker genes strongly and can silence the target gene efficiently upon Cre-mediated induction of the miRNA expression. This construct can be used to increase the efficiency of making cell lines or transgenic animals that stably express miRNA targeting specific genes.</p

Temporal Convolutional Attention-based Network For Sequence Modeling

With the development of feed-forward models, the default model for sequence modeling has gradually evolved to replace recurrent networks. Many powerful feed-forward models based on convolutional networks and attention mechanism were proposed and show more potential to handle sequence modeling tasks. We wonder that is there an architecture that can not only achieve an approximate substitution of recurrent network, but also absorb the advantages of feed-forward models. So we propose an exploratory architecture referred to Temporal Convolutional Attention-based Network (TCAN) which combines temporal convolutional network and attention mechanism. TCAN includes two parts, one is Temporal Attention (TA) which captures relevant features inside the sequence, the other is Enhanced Residual (ER) which extracts shallow layer's important information and transfers to deep layers. We improve the state-of-the-art results of bpc/perplexity to 26.92 on word-level PTB, 1.043 on character-level PTB, and 6.66 on WikiText-2.Comment: 7 pages, 4 figure

Wuxi – a Chinese City on its Way to a Low Carbon Future

Urbanization and climate change are amongst the greatest challenges of the 21st century. In the “Low Carbon Future Cities” project (LCFC), three important problem dimensions are analysed: current and future GHG emissions and their mitigation (up to 2050), resource use and material flows and vulnerability to climate change. The industrial city of Wuxi has been the Chinese pilot city of the project. To establish the pathway for a low carbon future, it is crucial to understand the current situation and possible future developments. The paper presents the key results of the status quo analysis and the future scenario analysis carried out for Wuxi. Two scenarios are outlined. The Current Policy Scenario (CPS) shows the current most likely development in the area of energy demand and GHG emissions until 2050. Whereas the extra low carbon scenario (ELCS) assumes a significantly more ambitious implementation, it combines a market introduction of best available technologies with substantial behavioural change. All scenarios are composed of sub-scenarios for the selected key sectors. Looking at the per capita emissions in Wuxi, the current levels are already high at around 12 tonnes CO2 per capita compared to Western European cities. Although Wuxi has developed a low carbon plan, the projected results under current policies (CPS) show that the total emissions would increase to 23.6 tonnes CO2 per capita by 2050. If the ELCS pathway was to be adopted, these CO2 emission levels could be reduced to 6.4 tonnes per capita by 2050. However, this is not a problem unique to Wuxi or China. A comprehensive rethink at global level on how to increase energy and resource efficiency and sustainability is required

Importance-based Resilience Assessment and Optimization of Unmanned Ship Swarm System

Based on the unmanned ship swarm system, a resilience model for unmanned ship swarms is proposed by comprehensively considering the preventive indicators, robustness indicators, recoverability indicators, and reconfigurability indicators of the swarm system. Firstly, preventive and robust indicators are proposed based on the characteristics of the unmanned ship swarm system, and the improvement of system performance efficiency by redundant unmanned ships is established as a recoverability indicator. Then, reconfigurable indicators are proposed based on importance, and the resilience indicator of the unmanned ship swarm is determined. Finally, a numerical example is used to model and simulate the performance change and capricious process of the unmanned ship swarm. Most of the research on the resilience assessment model of unmanned ship swarms considered too single indicators. The model of the unmanned ship swarm under attack is constructed, and the superiority of the resilience optimization strategy proposed in this paper is verified

Effect of zinc acetate concentration on optimization of photocatalytic activity of p-Co3O4/n-ZnO heterostructures

In this work, p-Co3O4/n-ZnO heterostructures were fabricated on Ni substrate by hydrothermal-decomposition method using cobaltous nitrate hexahydrate (Co(NO3)(2)center dot 6H(2)O) and zinc acetate dihydrate (Zn(CH3COO)(2)center dot 2H(2)O) as precursors with zinc acetate concentration varying from 5.0 to 55.0 mM. Structure and morphology of the developed samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Effect of zinc acetate concentration on the photocatalytic activity of p-Co3O4/n-ZnO heterostructures was investigated by degradation of methyl orange (MO) under the UV light irradiation. The fabricated p-Co3O4/n-ZnO heterostructures exhibited higher photocatalytic activity than pure Co3O4 particles. In order to obtain the maximum photocatalytic activity, zinc acetate concentration was optimized. Specifically, at 35 mM of zinc acetate, the p-Co3O4/n-ZnO showed the highest photocatalytic activity with the degradation efficiency of MO reaching 89.38% after 72 h irradiation. The improvement of photocatalytic performance of p-Co3O4/n-ZnO heterostructures is due to the increased concentration of photo-generated holes on Co3O4 surface and the higher surface-to-volume ratio in the hierarchical structure formed by nano-lamellas

Exploring the interplay between circadian rhythms and prostate cancer: insights into androgen receptor signaling and therapeutic opportunities

Circadian rhythm disruption is closely related to increased incidence of prostate cancer. Incorporating circadian rhythms into the study of prostate cancer pathogenesis can provide a more comprehensive understanding of the causes of cancer and offer new options for precise treatment. Therefore, this article comprehensively summarizes the epidemiology of prostate cancer, expounds the contradictory relationship between circadian rhythm disorders and prostate cancer risk, and elucidates the relationship between circadian rhythm regulators and the incidence of prostate cancer. Importantly, this article also focuses on the correlation between circadian rhythms and androgen receptor signaling pathways, as well as the applicability of time therapy in prostate cancer. This may prove significant in enhancing the clinical treatment of prostate cancer