Q-Class Authentication System for Double Arbiter PUF

Physically Unclonable Function (PUF) is a cryptographic primitive that is based on physical property of each entity or Integrated Circuit (IC) chip. It is expected that PUF be used in security applications such as ID generation and authentication. Some responses from PUF are unreliable, and they are usually discarded. In this paper, we propose a new PUF-based authentication system that exploits information of unreliable responses. In the proposed method, each response is categorized into multiple classes by its unreliability evaluated by feeding the same challenges several times. This authentication system is named Q-class authentication, where Q is the number of classes. We perform experiments assuming a challenge-response authentication system with a certain threshold of errors. Considering 4-class separation for 4-1 Double Arbiter PUF, it is figured out that the advantage of a legitimate prover against a clone is improved form 24% to 36% in terms of success rate. In other words, it is possible to improve the tolerance of machine-learning attack by using unreliable information that was previously regarded disadvantageous to authentication systems

String Theory on AdS_3 as Discrete Light-Cone Liouville Theory

We investigate (super) string theory on $AdS_3$ background based on an approach of free field realization. We demonstrate that this string theory can be reformulated as a string theory defined on a linear dilaton background along the transverse direction (``Liouville mode'') and compactified onto $S^1$ along a {\em light-like} direction. Under this reformulation we analyze the physical spectrum as that of a free field system, and discuss the consequences when we turn on the Liouville potential. The discrete light-cone momentum in our framework is naturally interpreted as the ``winding number'' of the long string configuration and is identified with the spectral flow parameter that is introduced in the recent work by Maldacena and Ooguri \cite{MO}. Moreover we show that there exist infinite number of the on-shell chiral primary states possessing the different light-cone momenta and the spectral flow consistently acts on the space of chiral primaries. We observe that they are also chiral primaries in the sense of space-time (or the conformal theory of long string) and the spectrum of space-time $U(1)_R$ charge is consistent with the expectation from the $AdS_3/CFT_2$-duality. We also clarify the correspondence between our framework and the symmetric orbifold theory of multiple long string system \cite{HS2}.Comment: 41 pages, no figure, the version to appear in Nucl. Phys. B. Section 3 and 4 are improved, and a discussion about the multiple long string system is adde

Seasonal Variation of Arbuscular Mycorrhizal Fungal Colonization for Coexisting Plant Species in Miscanthus-Type Semi-Natural Grassland

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Grazing Use of Native Pastures by Beef Cattle in Japan : Recent Researches on Plant-animal Interactions in Native Pastures

Understandings of plant-animal interactions are vital for adequate control of vegetation and animal conditions and sustainable use of the natural resources in grazing systems. In this paper, studies of plant-animal interactions that were carried out in native pastures at the Kawatabi Field Science Center (KFSC) in Tohoku University were reviewed. 1. Although forage quality of native grasses is known to lower than that of grasses in sown temperate pastures, fresh and masticated native grasses have higher ruminal degradability than dried and ground ones, indicating the importance of using fresh samples when estimating the nutritive value and ruminal digestibility. Native pastures are also suggested to supply more copper to animals than sown pastures. 2. The indigenous vegetation of the KFSC is composed of 61-80 plant species, of which cattle graze upon 44-75 species. Among these species, Miscanthus sinensis, Zoysia japonica and Sasa palmata are especially valuable for cattle grazing in Japanese native pastures. A new technique using plant opal phytoliths as markers is effective to obtain information on intake of individual plant species. 3. Studies of grazing impacts of cattle on plant succession are also essential to the grazing system in a native pasture. In the KFSC, shrubs such as Weigela hortensis have been increasing in M. sinensis pastures by cattle grazing, due to a decline in aboveground biomass and seed production of M. sinensis, and the removal of litter on the ground. Seed dispersal by grazing animals also exerts significant effects on vegetational change. 4. Beyond these studies, estimating environmental impacts of grazing on such ecosystems will require long-term investigations and quantification of nutrient flow in native pastures, including soil and soil microorganisms as variables

Absorption of Horseradish Peroxidase (HRP) In Vitro Across Bovine Jejunal and Ileal Epithelia Around the Time of Weaning

Using the everted sac methodology as well as an Ussing chamber, we investigated changes in the absorption of horseradish peroxidase (EC 1.11.1.7, HRP (40 kDa)) in jejunum and ileum segments isolated from male Holstein cattle around the time of weaning (6 to 15 wks old). By the everted sac method, HRP transport (HRP concentration on the serosal side sampled after a 60-min-incubation) at 15 wks of age was significantly greater than that at 6 wks of age, in both segments of the intestine. Absorption was not significantly different between the jejunum and ileum. Addition of Na^+/K^+ ATPase inhibitor (ouabain, 1 mM) did not cause any significant change in HRP absorption, whereas Na^+/H^+ anti-transporter inhibitor (amiloride, 1μM) significantly increased the absorption in both sacs at 8 wks of age. By the Ussing chamber method, there were no significant differences between the values for Jsm and Jms, while the Jnet value was nearly zero for both epithelia. In addition, the flux (Jms) of Lucifer yellow, a cell-membrane-impermeable fluorescence dye, was significantly greater at 6 than at 13 wks of age in the ileal epithelia, although the flux was significantly greater in the jejunal than the ileal epithelia at both ages. From these findings, we conclude that: 1) bovine jejunal and ileal epithelia are able to absorb a large molecule such as the HRP protein; 2) HRP transport occurs in a concentration-dependent manner and may in part be via a paracellular pathway; 3) the increased HRP transport shown at 15 wks of age may not be caused by an increased use of the paracellular pathway.horseradish peroxidaseabsorptiontransportcal