Reliability Analysis of Hafnium Oxide Dielectric Based Nanoelectronics

With the physical dimensions ever scaling down, the increasing level of sophistication in nano-electronics requires a comprehensive and multidisciplinary reliability investigation. A kind of nano-devices, HfO2-based high-k dielectric films, are studied in the statistical aspect of reliability as well as electrical and physical aspects of reliability characterization, including charge trapping and degradation mechanisms, breakdown modes and bathtub failure rate estimation. This research characterizes charge trapping and investigates degradation mechanisms in high-k dielectrics. Positive charges trapped in both bulk and interface contribute to the interface state generation and flat band voltage shift when electrons are injected from the gate under a negative gate bias condition.A negligible number of defects are generated until the stress voltage increases to a certain level. As results of hot electrons and positive charges trapped in the interface region, the difference in the breakdown sequence is attributed to the physical thickness of the bulk high-k layer and the structure of the interface layer. Time-to-breakdown data collected in the accelerated life tests are modeled with a bathtub failure rate curve by a 3-step Bayesian approach. Rather than individually considering each stress level in accelerating life tests (ALT), this approach derives the change point and the priors for Bayesian analysis from the time-to-failure data under neighborhood stresses, based on the relationship between the lifetime and stress voltage. This method can provide a fast and reliable estimation of failure rate for burn-in optimization when only a small sample of data is available

The roles of endoglin gene in cerebrovascular diseases.

Endoglin (ENG, also known as CD105) is a transforming growth factor β (TGFβ) associated receptor and is required for both vasculogenesis and angiogenesis. Angiogenesis is important in the development of cerebral vasculature and in the pathogenesis of cerebral vascular diseases. ENG is an essential component of the endothelial nitric oxide synthase activation complex. Animal studies showed that ENG deficiency impairs stroke recovery. ENG deficiency also impairs the regulation of vascular tone, which contributes to the pathogenesis of brain arteriovenous malformation (bAVM) and vasospasm. In human, functional haploinsufficiency of ENG gene causes type I hereditary hemorrhagic telangiectasia (HHT1), an autosomal dominant disorder. Compared to normal population, HHT1 patients have a higher prevalence of AVM in multiple organs including the brain. Vessels in bAVM are fragile and tend to rupture, causing hemorrhagic stroke. High prevalence of pulmonary AVM in HHT1 patients are associated with a higher incidence of paradoxical embolism in the cerebral circulation causing ischemic brain injury. Therefore, HHT1 patients are at risk for both hemorrhagic and ischemic stroke. This review summarizes the possible mechanism of ENG in the pathogenesis of cerebrovascular diseases in experimental animal models and in patients

Matching Users' Preference Under Target Revenue Constraints in Optimal Data Recommendation Systems

This paper focuses on the problem of finding a particular data recommendation strategy based on the user preferences and a system expected revenue. To this end, we formulate this problem as an optimization by designing the recommendation mechanism as close to the user behavior as possible with a certain revenue constraint. In fact, the optimal recommendation distribution is the one that is the closest to the utility distribution in the sense of relative entropy and satisfies expected revenue. We show that the optimal recommendation distribution follows the same form as the message importance measure (MIM) if the target revenue is reasonable, i.e., neither too small nor too large. Therefore, the optimal recommendation distribution can be regarded as the normalized MIM, where the parameter, called importance coefficient, presents the concern of the system and switches the attention of the system over data sets with different occurring probability. By adjusting the importance coefficient, our MIM based framework of data recommendation can then be applied to system with various system requirements and data distributions.Therefore,the obtained results illustrate the physical meaning of MIM from the data recommendation perspective and validate the rationality of MIM in one aspect.Comment: 36 pages, 6 figure

State Control, Marketization, And Firm Value: Evidence From China

Using a firm-level panel data of Chinese listed firms, this paper examines the effects of state control on firm value and the different impacts that have under different degree of marketization deeply. The results show: compared with non-state controlled firms, state controlled firms are imposed by much policy burden and have more serious tunneling or expropriation behaviors. Therefore, firm values in state controlled firms are lower than in non-state controlled firms. For state controlled firms, the lower the government administrative ranks, the more serious the intervention or expropriation behaviors imposed by government, and thus the lower the firm value. Compared with low marketization regions, the negative effects of state control and low government administrative rank control on firm value is relatively smaller in regions with high degree of marketization

The unexpected magnetism in 2D group-IV-doped GaN for spintronic applications

In this study, the structural and magnetic properties of group-IV-doped monolayer GaN were systematically investigated by first-principles calculations. Among all the group-IV dopants, only Ge and Sn atoms prefer to substitute the Ga atom of monolayer GaN and form a buckling structure with a magnetic moment of 1 $\mu_B$ per dopant. The N-rich growth conditions are more desirable for such a substitution process than the Ga-rich grow conditions. With a large diffusion barrier vertical to the monolayer GaN, both Ge and Sn atoms tend to stay on the same side of monolayer GaN with an antiferromagnetic coupling between them. When intrinsic vacancies exist in monolayer GaN, the magnetic moments of group-IV dopants vanish due to the charge transferring from the dopants to Ga or N vacancies. The precondition creation of Ga vacancies, a plentiful supply of Ge or Sn dopants, and the N-rich conditions can be adopted to maintain the magnetic properties of group-IV-doped monolayer GaN. These theoretical results help to promote the applications of 2D GaN-based materials in spintronics

Silencing of host genes directed by virus-derived short interfering RNAs in Caenorhabditis elegans

Small interfering RNAs (siRNAs) processed from viral replication intermediates by RNase III-like enzyme Dicer guidesequence-specific antiviral silencing in fungi, plants, and invertebrates. In plants, virus-derived siRNAs (viRNAs) can target and silence cellular transcripts and, in some cases, are responsible for the induction of plant diseases. Currently it remains unclear whether viRNAs are also capable of modulating the expression of cellular genes in the animal kingdom, although animal virus-encoded microRNAs (miRNAs) are known to guide efficient silencing of host genes, thereby facilitating virus replication. In this report, we showed that viRNAs derived from a modified nodavirus triggered potent silencing of homologous cellular transcripts produced by the endogenous gene or transgene in the nematode worm Caenorhabditis elegans.Like that found in plants, virus-induced gene silencing (VIGS) in C. elegans also involves RRF-1, a worm RNA-dependent RNA polymerase (RdRP) that is known to produce single-stranded secondary siRNAs in a Dicer-independent manner. We further demonstrated that VIGS in C. elegans is inheritable, suggesting that VIGS has the potential to generate profound epigenetic consequences in future generations. Altogether, these findings, for the first time, confirmed that viRNAshave the potential to modulate host gene expression in the animal kingdom. Most importantly, the success in uncoupling the trigger and the target of the antiviral silencing would allow for the exploration of novel features of virus-host interactions mediated by viRNAs in the animal kingdom. © 2012, American Society for Microbiology

Effects of zero and reversed magnetic shear on resistive wall modes in a limiter tokamak plasma

Advanced tokamak scenarios often feature equilibriums with zero and reversed magnetic shear. To isolate and investigate their impacts on the resistive wall mode (RWM) instability analytically, we construct a series of cylindrical limiter equilibriums with reversed magnetic shear in the core and zero magnetic shear towards plasma edge, as a prototype of the configurations in advanced tokamak scenarios. Uniform plasma pressure is assumed, so that we can focus our analysis on the current-driven RWMs. Based on the reduced ideal MHD equations, analytical solutions for the $n=1$ resistive wall mode are obtained, which indicate that increasing the reversal of magnetic shear in the core region enhances the RWM instability, whereas the widened region of zero shear near edge leads to lower growth rate of RWM, except when the $q$ value with zero magnetic shear approaches rational values. On the other hand, enhanced positive shear at plasma edge is found to be stabilizing on RWM. NIMROD calculation results confirm these analytical findings