自然数196的回文数猜想检验的新算法

回文教的猜想是一个著名的数学命题,尤其是特殊的自然数196的回文数,到目前为止尚未得到证实.在字长为32位的计算机上,如果使用整型变量进行处理,最多能检验到17步,使用整型数组的计算量也不过上万步.为了继续检验,提出了用字符数组存储原数、新数和逆序数的新算法,突破了WindowsXP 32位字长的限制,可以达到上千万步的运算量.     

基于VC的回文数猜想检验算法

回文数猜想是一个著名的数学问题,尤其是自然数196,至今尚未证实是否是Lychrel数。为了在32位计算机上实现检验回文数猜想的196算法,提出在VC＋＋平台下用字符串来实现。给出了算法的具体形式,对程序中每一个步骤予以详细说明。最后实验证实了算法突破了Windows XP的32位字长限制。     

Dissection of centromeric DNA from yeast Yarrowia lipolytica and identification of protein-binding site required for plasmid transmission

In a dimorphic yeast, Yarrowia lipolytica, replicative plasmids can be established only in the coexistence of the replication origin (ORI) and centromere (CEN) from its own chromosomal DNA. Although six CEN sequences so far isolated from this yeast exhibit no similarity with conventional CEN DNA elements from other budding yeasts, they are confined within short regions (approximately 0.2 kb) and contain various conserved sequence blocks. We surveyed here a CEN1-1 sequence on an ORI-containing plasmid by deletion and site-directed mutagenesis, and found a partial palindrome, CCTAATTTGG designated DS9, to be an essential element for high-efficiency transformation. In particular, point mutations that alter symmetry and/or length of the palindrome abrogated the activity of CEN1-1. Gel mobility shift assay of CEN1-1 DNA fragments incubated with Y. lipolytica nuclear proteins revealed four bands corresponding to protein-DNA complexes, whereas the mutations within DS9 that disabled transformation also abolished the formation of part of these complexes, depending on particular mutations. These results demonstrate that the palindrome is a binding site for specific protein(s) necessary for plasmid transmission in Y. lipolytica.     

Solutions to the involution language equation

In this paper, we study a generalization of the classical notions of language equations: involution language equations. This notion is motivated by DNA strand design where Watson–Crick complementarity can be modular as an antimorphic involution function. Characterizations of words u and languages A and B which satisfy the equation θ(u)B=Au are obtained. For a language L, solutions of the equation θ(L)B=AL are considered. We also study the characteristics of L _θ-commutative equivalent languages.     

Partial Symmetry in Cellular Automata Rule Vectors

This letter demonstrates a partial symmetry in the rule vectors ofone-dimensional linear hybrid cellular automata (CA). The symmetry wasdiscovered in the CA realizations of the minimal cost primitive polynomialspublished by Bardell (1992). This symmetry turns out to be a simple functionof the structure of the polynomials coefficients, though the proof of thisseems to be far from trivial. This letter presents the symmetry function,and outlines its proof.     

Real-time recognition of substring repetition and reversal

Real-time multitape Turing machine algorithms are presented for recognizing the languages {wxyxz^*:|w|=r|x,|z| =t|x|} and {wxyx ^R _z ^*:|w|=r|x,|z| =t|x|} for fixedr, s, andt and for string-matching with forced mismatches.This research was supported in part by the National Science Foundation under Grant MCS77-06613 (first author) and the Bat-Sheva Fund (second author). Part of the work was conducted while the second author was at the IBM Thomas J. Watson Research Center, Yorktown Heights, New York. A preliminary report was included in a paper the authors presented at the Seventeenth Annual IEEE Symposium on Foundations of Computer Science, Houston, Texas, October 1976.     

CRISPR/Cas系统在食品质量安全检测中的应用研究进展

规律间隔成簇短回文重复序列(regularly spaced clustered short palindrome repeats-associated, CRISPR/Cas)系统是基于原核生物的一种适应性免疫系统, 因其可编程性和易操作的优点已被开发为基因编辑技术, 并且凭借其快速和高效的特点被广泛用于生物、医学等领域。目前, CRISPR/Cas系统已开始在基于核酸检测和单核苷酸多态性检测等食品安全检测技术中应用。本文就CRISPR/Cas系统中Cas9、Cas12a和Cas13a的原理以及其在掺假检测、溯源检测、食源性微生物和动物疫病等食品质量安全检测中的应用进展进行了综述, 以期为CRISPR/Cas系统应用于食品质量安全的快速现场检测提供理论和技术参考。