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Abstract-The lack of stability is one of the major limitations that constrains Physical Unclonable Function (PUF) from being put in widespread practical use. In this paper, we propose a weak PUF and a strong PUF that are both completely stable with 0% intra-distance. These PUFs are called Locally Enhanced Defectivity Physical Unclonable Function (LEDPUF). The source of randomness of a LEDPUF is extracted from locally enhance defectivity without affecting other parts of the chip. A LEDPUF is a pure functional PUF that does not require helper data, fuzzy comparator, or any kinds of correction schemes as conventional parametric PUFs do. A weak LEDPUF is constructed by forming arrays of Directed Self Assembly (DSA) random connections is presented, and the strong LEDPUF is implemented by using the weak LEDPUF as the key of a keyed-hash message authentication code (HMAC). Our simulation and statistical results show that the entropy of the weak LEDPUF bits is close to ideal, and the inter-distances of both weak and strong LEDPUFs are about 50%, which means that these LEDPUFs are not only stable but also unique.We develop a new unified framework for evaluating the level of security of PUFs, based on password security, by using information theoretic tools of guesswork. The guesswork model allows to quantitatively compare, with a single unified metric, PUFs with varying levels of stability, bias and available side information. In addition, it generalizes other measures to evaluate the security level such as min-entropy and mutual information. We evaluate guesswork-based security of some measured SRAM and Ring Oscillator PUFs as an example and compare them with LEDPUF to show that stability has a more severe impact on the PUF security than biased responses. Furthermore, we find the guesswork of three new problems: Guesswork under probability of attack failure, the guesswork of idealized version of a message authentication code, and the guesswork of strong PUFs that are used for authentication.

Hepatoma cells are relatively resistant to TRAIL. We have previously shown that isoobtusilactone A (IOA), a potent anticancer agent isolated from Cinnamomum kotoense, induced mitochondria-mediated apoptosis in hepatoma cells. Here, we report that IOA could potentiate TRAIL-induced apoptosis in Hep G2 cells. The combined treatment with IOA and TRAIL significantly induced caspase-dependent apoptosis. This correlated with the up-regulation of C/EBP homologous protein (CHOP) and death receptor 5 (DR5) protein levels. Gene silencing of the DR5 by small interfering RNA abrogated the apoptosis induced by the combined regimen of IOA and TRAIL, suggesting that the sensitization to TRAIL was mediated through DR5. By analyzing the DR5 promoter, we found that IOA induced a CHOP-dependent DR5 transactivation. DR5 expression after IOA treatment was accompanied by provoking intracellular reactive oxygen species (ROS) generation. Pretreatment with N-acetyl-L-cysteine (NAC) attenuated IOA-induced CHOP and DR5 expression and inhibited TRAIL-induced apoptosis. Taken together, our data suggested that ROS-dependent and CHOP-regulated DR5 expression played a pivotal role in the synergistic enhancement of TRAIL-induced apoptosis instigated by IOA in Hep G2 cells.

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Abstract-Vertical gate-all-around (VGAA) has been shown to be one of the most promising devices for the scaling beyond 10nm for its reduced delay, large driving current, and good gate control. Moreover, emerging devices such as heterojunction tunneling FETs are more amenable to vertical fabrication. However, past studies of vertical channel devices focused more on regular memory architectures and simple standard cells like inverter. Since naive migration of regular FinFET layouts to vertical FETs yields little benefits, we identify several vertical efficient layout structures and propose novel layout generation heuristics for vertical channel devices. We also compare VGAA with symmetric and asymmetric source/drain architectures. The layout efficiencies of several VGAA structures, vertical double gate (VDG), lateral gate-all-around (LGAA), and FinFET are presented in our experiments. We observe that even though most vertical channel standard cells have more diffusion gaps than lateral cells do, they still benefit from vertical architectures in area because of the elimination of diffusion contacts. For asymmetric architectures, the area is larger than symmetric architectures because of the extra diffusion gaps needed, but our experiments indicate that for both symmetric and asymmetric architectures, vertical channel devices are likely to have a density advantage over lateral channel devices assuming that current drive strengths of both are similar.