The undecidability of self-embedding for term rewriting systems

The self-embedding property of term rewriting systems is closely related to the uniform termination property, since a nonself-embedding term rewriting system is uniform terminating. The self-embedding property is shown to be undecidable and partially decidable. It follows that the nonself-embedding property is not partially decidable. This is true even for globally finite term rewriting systems. The same construction gives an easy alternate proof that uniform termination is undecidable in general and also for globally finite term rewriting systems. Also, the looping property is shown to be undecidable in the same way.     

[PSI] and [URE3] as yeast prions

[URE3] is a non-Mendelian genetic element that mimics recessive mutations in the chromosomal URE2 gene making cells derepressed for nitrogen catabolic enzymes. [PSI] is a non-Mendelian enhancer of readthrough of translational termination similar in its effects to some mutations in the chromosomal SUP35 gene. Three lines of evidence led to the proposal⁷⁵ that both [URE3] and [PSI] are prions, infectious proteins analogous to the scrapie agent mediating transmissible spongiform encephalopathies of mammals. (1) Both [PSI] and [URE3] are reversibly curable. (2) [PSI] propagation requires SUP35 and [URE3] propagation requires URE2 with recessive chromosomal mutants having the same phenotypes as the presence of the respective dominant non-Mendelian element. (3) Overproduction of Sup35p and Ure2p increases the frequency of cells acquiring [PSI] or [URE3], respectively.     

A Fully Integrated Current-Steering 10-b CMOS D/A Converter with a Self-Calibrated Current Bias Circuit

A fully integrated current-steering 10-b CMOS Digital-to-Analog Converter with internal termination resistors is presented. In order to improve the device-mismatching problem of internal termination resistors, a self-calibrated current bias circuit is designed. With the self-calibrated current bias circuit, the gain error of the output voltage swing is reduced within 0.5%. For the purpose of reducing glitch noises, further, a novel current switch based on a deglitching circuit is proposed. The prototype circuit has been fabricated with a 3 V 0.35 μm 2-poly 3-metal CMOS technology, and it occupies 1350 × 750 μm silicon area with 45 mW power consumption. The measured INL and DNL are within 0.5 LSB, respectively. The measured SFDR is about 65 dB, when an input signal is about 8 MHz at 100 MHz clock frequency.     

Unification Grammars and Off-Line Parsability

Unification grammars are known to be Turing-equivalent; given a grammar G and a word w, it is undecidable whether w L(G). In order to ensure decidability, several constraints on grammars, commonly known as off-line parsability (OLP), were suggested, such that the recognition problem is decidable for grammars which satisfy OLP. An open question is whether it is decidable if a given grammar satisfies OLP. In this paper we investigate various definitions of OLP and discuss their interrelations, proving that some of the OLP variants are indeed undecidable. We then present a novel, decidable OLP constraint which is more liberal than the existing decidable ones.     

The postherapy period.

18 mo. after psychotherapy, a variety of tests were read-ministered to 69 available Ss constituting a biased subgroup from 93 tested previously at the beginning and at the termination of therapy. While the group as a whole showed no reliable movement after therapy, individuals made reliable and correlated changes. Only the Ss' direct report of such change was found to be predictable from several earlier measures. Less favorable movement was found on some measures for the 16 Ss who had additional therapy. While status at termination of therapy appears to be an adequate index of group effects associated with therapy, individuals show systematic trends in the subsequent 18 mo. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

微波电路用共面电极TaNx薄膜片式电阻器

采用反应溅射方法制作TaNx电阻薄膜,并通过溅射Ni、Au形成双层共面电极。研究了溅射条件对电阻薄膜组分的影响以及此类电阻器的微波特性。结果显示,溅射工作真空度小于0.5Pa,氮气体积分数大于5%时,可以得到阻值稳定的六方晶体结构TaNx电阻薄膜,其共面电极的电阻器使用频率上限大于20GHz。     

MT-E50F深水钻井隔水管终端接头研制

为满足深水钻井隔水管系统的需要,采用等强度螺栓连接、高压动态密封、高强度厚壁管体全熔透对接焊接等技术,研制了MT-E50F型深水隔水管终端接头,并进行了8 896 kN载荷试验、静水压试验和连接互换性试验。试验结果表明,MT-E50F型隔水管终端接头满足深水使用要求和载荷工作要求,密封性能可靠。提出了进一步完成MT-E50F型隔水管终端接头深水水下工业性海试、开展隔水管LMRP系统集成研究和试验等建议。该装置的成功开发对海洋钻井隔水管系统国产化具有一定的参考作用。     

Ending child psychotherapy: Continuing the cycle of life.

Focuses on the termination of psychoanalytic treatment with young children, taking into account the relationship to the parents and its impact on the conduct of treatment, especially at the sensitive ending phase. The author reflects on D. W. Winnicott's (1977) case, "The Piggle," from this perspective. The verbatim notes and comments offer a classic, detailed example of the complex factors impinging upon the conclusion of treating a young child and the wisdom of an outstanding therapist. A 2nd case of a 7-yr-old girl who came to treatment because of a reaction of delayed mourning is also reviewed. The case illustrates the issues involved in the early traumatic loss of a parent, how this loss is reflected within the transference relationship, and the subsequent unfolding of treatment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

适用于迭代型去模糊算法粗精检测相结合的自适应终止机制

由于缺乏合适的去模糊图像质量度量方法,迭代型去模糊算法通常将其迭代次数简单地设置为固定值,无法在执行效率和去模糊质量之间获得最优的平衡点。为此,提出一种粗精检测相结合的迭代终止机制并将其应用到迭代型去模糊算法中以自适应地确定它们最佳的迭代次数。具体地,在每一步迭代过程中利用伪PSNR值细粒度地判断去模糊图像质量是否趋于稳定,另一方面每隔若干步利用从反向卷积残差图像中提取的统计特征值粗粒度准确地判定图像质量是否达到最佳,将两种去模糊图像质量度量方法有机结合以实现一种效率高且准确的迭代终止判定机制。评估结果显示,将所提出的粗精相结合的终止机制应用于NCSR、GSR和ADMM共三种主流去模糊算法后,执行效率可提高50%左右,而去模糊图像质量也得到了最佳保证。实验结果表明,提出的检测机制能够有效地解决各种迭代型去模糊算法因采用固定迭代次数而存在的无益迭代和过迭代问题,非常具有普适性。     

Atomic-Scale Metal–Insulator Transition in SrRuO3 Ultrathin Films Triggered by Surface Termination Conversion

The metal–insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO₃ ultrathin films is reported. Uniform and effective termination engineering at the SrRuO₃(001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO₂, a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO₃ monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision.