Protecting Memories against Soft Errors: The Case for Customizable Error Correction Codes

As technology scales, radiation induced soft errors create more complex error patterns in memories with a single particle corrupting several bits. This poses a challenge to the Error Correction Codes (ECCs) traditionally used to protect memories that can correct only single bit errors. During the last decade, a number of codes have been developed to correct the emerging error patterns, focusing initially on double adjacent errors and later on three bit burst errors. However, as the memory cells get smaller and smaller, the error patterns created by radiation will continue to change and thus new codes will be needed. In addition, the memory layout and the technology used may also make some patterns more likely than others. For example, in some memories, there maybe elements that separate blocks of bits in a word, making errors that affect two blocks less likely. Finally, for a given memory, depending on the data stored, some error patterns may be more critical than others. For example, if numbers are stored in the memory, in most cases, errors on the more significant bits have a larger impact. Therefore, for a given memory and application, to achieve optimal protection, we would like to have a code that corrects a given set of patterns. This is not possible today as there is a limited number of code choices available in terms of correctable error patterns and word lengths. However, most of the codes used to protect memories are linear block codes that have a regular structure and which design can be automated. In this paper, we propose the automation of error correction code design for memory protection. To that end, we introduce a software tool that given a word length and the error patterns that need to be corrected, produces a linear block code described by its parity check matrix and also the bit placement. The benefits of this automated design approach are illustrated with several case studies. Finally, the tool is made available so that designers can easily produce custom error correction codes for their specific needs.Jiaqiang Li and Liyi Xiao would like to acknowledge the support of the Fundamental Research Funds for the Central Universities (Grant No. HIT.KISTP.201404), Harbin science and innovation research special fund (2015RAXXJ003), and Special found for development of Shenzhen strategic emerging industries (JCYJ20150625142543456). Pedro Reviriego would like to acknowledge the support of the TEXEO project TEC2016-80339-R funded by the Spanish Ministry of Economy and Competitivity and of the Madrid Community research project TAPIR-CM Grant No. P2018/TCS-4496

Co-administration of a DNA vaccine encoding the prostate specific membrane antigen and CpG oligodeoxynucleotides suppresses tumor growth

BACKGROUND: Prostate-specific membrane antigen (PSMA) is a well characterized prostate-specific tumor associated antigen. Its expression is elevated in prostate carcinoma, particularly in metastatic and recurrent lesions. These observations suggest that PSMA can be used as immune target to induce tumor cell-specific recognition by the host and, consequently tumor rejection. We utilized a DNA-based vaccine to specifically enhance PSMA expression. An immune modulator, such as CpG oligodeoxynucleotides which promote Th1-type immune responses was combined to increase the efficacy of tumor recognition and elimination. METHODS: A eukaryotic expression plasmid pCDNA3.1-PSMA encoding full-length PSMA was constructed. C57BL/6 mice were immunized with endotoxin-free pCDNA3.1-PSMA alone or in combination with CpG oligodeoxynucleotides by intramuscular injection. After 4 immunizations, PSMA specific antibodies and cytotoxic T lymphocyte reactivity were measured. Immunized C57BL/6 mice were also challenged subcutaneously with B16 cells transfected with PSMA to evaluate suppression of tumor growth. RESULTS: Vaccine-specific cytotoxic T lymphocytes reactive with B16 cells expressing PSMA could be induced with this treatment schedule. Immune protection was observed in vaccinated mice as indicated by increased tumor growth in the control group (100%) compared with the groups vaccinated with DNA alone (66.7%) or DNA plus CpG oligodeoxynucleotides (50%) respectively. Average tumor volume was smaller in vaccinated groups and tumor-free survival time was prolonged by the vaccination. CONCLUSION: The current findings suggest that specific anti-tumor immune response can be induced by DNA vaccines expressing PSMA. In addition, the suppression of in vivo growth of tumor cells expressing PSMA was augmented by CpG oligodeoxynucleotides. This strategy may provide a new venue for the treatment of carcinoma of prostate after failure of standard therapy

Spatial popularity and similarity of watching videos in a large city

With the popularity of watching mobile videos, many works focus on the geographic features of user viewing behaviors, but few study them in the context of an entire metropolitan city. Different regions of a large city have different intensity of economy activities with respect to their different distances to the downtown, and how this will influence video popularity and similarity is still unclear. To quantitatively study the spatial popularity and similarity of watching videos in a large urban environment, we collect a dataset with two-month video view requests from the largest network provider in Shanghai, containing top six content providers, and study the spatial features of video access in regions of different scales. We find that 1) video popularity and similarity exist at different scales of city division; 2) the concentration of video popularity becomes higher as the region is closer to downtown; 3) when comparing the regions of same scale, the similarity of popular videos becomes lower as the region is farther away from the downtown. Finally, we correlate our findings with cache deployment, advertising and video recommendation to illustrate the implication