A method for computing Lucas sequences

AbstractMost of public-key cryptosystems rely on one-way functions, which can be used to encrypt and sign messages. Their encryption and signature operations are based on the computation of exponentiation. Recently, some public-key cryptosystems are proposed and based on Lucas functions, and the Lucas sequences are performed as S = V(d)modN. In this paper, we will transform the concept of addition chains for computing the exponentiation evaluations to the Lucas chains for computing the Lucas sequences. Theoretically, the shorter Lucas chain for d is generated, the less computation time for evaluating the value V(d) is required. Therefore, we proposed a heuristic algorithm for evaluating a shorter Lucas chain and then use it to compute the Lucas sequence with less modular multiplications

An Elusive Vector Dark Matter

Even though the sensitivity of direct dark matter search experiments reach the level about $10^{-45}~{\rm cm}^2$, there is no confident signal of dark matter been observed. We point out that, if dark matter is a vector boson, the null result in direct dark matter search experiments may due to the destructive effects in dark-matter-nucleon elastic scattering. We illustrate the scenario using a modified Higgs portal model that includes exotic quarks. The significant cancellation can occur for certain mass gap between heavy quark and dark matter. As a result, the spin-independent dark-matter-nucleon elastic scattering is so suppressed that the future direct search experiments can hardly observe the signal of dark matter.Comment: 11 pages, 5 figure

TOXICOLOGICAL EVALUATION OF LEPISTA NUDA (BULL. EX FR.) COOKE MYCELIUM PRODUCED BY AN IN VITRO CULTURE METHODOLOGY

Objective: Considering the interest in L. nuda as a source of ingredients for the development of functional food and nutraceuticals has increased, the objective of this study was to evaluate its general toxicity and possible genotoxic effects in rats to assess its safety.Methods: This study evaluated the safety of L. nuda mycelium by using genotoxicity assays (reverse mutation, chromosomal aberration, and micronuclei tests) and a short-term toxicity test.Results: Our results have indicated that L. nuda mycelium did not significantly increase the number of revertant colonies and chromosomal aberration in both in vitro assays. Furthermore, it did not induce any increase in micronuclei formation in mouse bone marrow.Conclusion: In summary, no mutagenic effects and no evidence of systemic toxicity were found in this safety assessment, and the use of L. nuda mycelia is safe at a dose of 3 g/kg body weight in S-D rats. Using a safety factor of 100, the calculated acceptable daily intake in humans is 30 mg/kg body weight/d

A 90-DAY SUBCHRONIC TOXICOLOGICAL ASSESSMENT of DEINOCOCCUS GRANDIS FERMENTED SOYMILK IN SPRAGUE-DAWLEY RATS

Objective: Despite the fact that there was no adverse effect observed in previous animal safety studies of Deinococcus grandis (D. grandis) fermented soymilk, including acute oral toxicity assay, 3 different test systems of genotoxicity test and teratogenicity study, whether D. grandis fermented soymilk is safe for long-term use remains unknown. Therefore, the study was conducted further to clarify the edible safety of D. grandis fermented soymilk for long term use.Methods: Eighty Sprague-Dawley (SD) rats were divided into four groups, each consisting of ten male and ten female rats. Rats were orally administrated with reverse osmosis water (control) or 1,000, 2,000 and 3,000 mg/kg b.w./d freeze dried D. grandis fermented soymilk powder for 90 consecutive days. Clinical observation of the rats was carried out daily. The body weight and feed intake of the rats were recorded weekly. At the end of the study, all rats were sacrificed and the blood and organs were collected for hematology, clinical biochemistry and histopathological examination.Results: During the study period, no abnormality occurred in clinical signs, body weight, and ophthalmological examination. There were no significant differences in urinalysis, hematology and clinical biochemistry parameters between the treatment and control group. Necropsy and histopathological examination showed no treatment-related change.Conclusion: According to the results, the no-observed-adverse-effect level (NOAEL) of D. grandis fermented soymilk was greater than 3,000 mg/kg b.w./d in SD rats.Keywords: Deinococcus grandis (D. grandis), 90-day subchronic toxicity, NOAEL, Safety assessment, GKB-Aid 199

Paxillin facilitates timely neurite initiation on soft-substrate environments by interacting with the endocytic machinery.

Neurite initiation is the first step in neuronal development and occurs spontaneously in soft tissue environments. Although the mechanisms regulating the morphology of migratory cells on rigid substrates in cell culture are widely known, how soft environments modulate neurite initiation remains elusive. Using hydrogel cultures, pharmacologic inhibition, and genetic approaches, we reveal that paxillin-linked endocytosis and adhesion are components of a bistable switch controlling neurite initiation in a substrate modulus-dependent manner. On soft substrates, most paxillin binds to endocytic factors and facilitates vesicle invagination, elevating neuritogenic Rac1 activity and expression of genes encoding the endocytic machinery. By contrast, on rigid substrates, cells develop extensive adhesions, increase RhoA activity and sequester paxillin from the endocytic machinery, thereby delaying neurite initiation. Our results highlight paxillin as a core molecule in substrate modulus-controlled morphogenesis and define a mechanism whereby neuronal cells respond to environments exhibiting varying mechanical properties