A new SOLT calibration method for leaky on-wafer measurements using a 10-term error model

We present a new Short-Open-Load-Thru (SOLT) calibration method for on-wafer S-parameter measurements. The new calibration method is based on a 10-term error model which is a simplified version of the 16-term error model. Compared with the latter, the former ignores all signal leakages except the ones between the probes. Experimental results show that this is valid for modern vector network analyzers (VNA). The advantage of using this 10-term error model is that the exact values of all error terms can be obtained by using the same calibration standards as the conventional SOLT method. This avoids not only the singularity problem with approximate methods, such as least squares, but also the usage of additional calibration standards. In this paper, we first demonstrate how the 10-term error model is developed and then the experimental verification of the theory is given. Finally, a practical application of the error model using a 10 dB attenuator from 140 GHz to 220 GHz is presented. Compared with the conventional SOLT calibration method without crosstalk corrections, the new method shows approximately 1 dB improvement in the transmission coefficients of the attenuator at 220 GHz

A topological version of Furstenberg-Kesten theorem

Let $A(x): =(A_{i, j}(x))$ be a continuous function defined on some subshift of $\Omega:= \{0,1, \cdots, m-1\}^\mathbb{N}$, taking $d\times d$ non-negative matrices as values and let $\nu$ be an ergodic $\sigma$-invariant measure on the subshift where $\sigma$ is the shift map. Under the condition that $A(x)A(\sigma x)\cdots A(\sigma^{\ell-1} x)$ is a positive matrix for some point $x$ in the support of $\nu$ and some integer $\ell\ge 1$ and that every entry function $A_{i,j}(\cdot)$ is either identically zero or bounded from below by a positive number which is independent of $i$ and $j$, it is proved that for any $\nu$-generic point $\omega\in \Omega$, the limit defining the Lyapunov exponent $\lim_{n\to \infty} n^{-1} \log \|A(\omega) A(\sigma\omega)\cdots A(\sigma^{n-1}\omega)\|$ exists.Comment: 24 page

Ranking Biomedical Annotations with Annotator’s Semantic Relevancy

Biomedical annotation is a common and affective artifact for researchers to discuss, show opinion, and share discoveries. It becomes increasing popular in many online research communities, and implies much useful information. Ranking biomedical annotations is a critical problem for data user to efficiently get information. As the annotator’s knowledge about the annotated entity normally determines quality of the annotations, we evaluate the knowledge, that is, semantic relationship between them, in two ways. The first is extracting relational information from credible websites by mining association rules between an annotator and a biomedical entity. The second way is frequent pattern mining from historical annotations, which reveals common features of biomedical entities that an annotator can annotate with high quality. We propose a weighted and concept-extended RDF model to represent an annotator, a biomedical entity, and their background attributes and merge information from the two ways as the context of an annotator. Based on that, we present a method to rank the annotations by evaluating their correctness according to user’s vote and the semantic relevancy between the annotator and the annotated entity. The experimental results show that the approach is applicable and efficient even when data set is large

Object-Oriented Intensional Programming: Intensional Classes Using Java and Lucid

This article introduces Object-Oriented Intensional Programming (OO-IP), a new hybrid language between Object-Oriented and Intensional Programming Languages in the sense of the latest evolutions of Lucid. This new hybrid language combines the essential characteristics of Lucid and Java, and introduces the notion of object streams which makes it is possible that each element in a Lucid stream to be an object with embedded intensional properties. Interestingly, this hybrid language also brings to Java objects the power to explicitly express and manipulate the notion of context, creating the novel concept of intensional object, i.e. objects whose evaluation is context-dependent, which are here demonstrated to be translatable into standard objects. By this new approach, we extend the use and meaning of the notion of intensional objects and enrich the meaning of object streams in Lucid and semantics of intensional objects in Java.Comment: 27 pages, 8 listings, 2 tables, 5 figure

7-Fluoro-6-nitro­quinazolin-4(3H)-one

The quinazolinone unit of the title compound, C8H4FN3O3, is essentially planar, with a maximum deviation of 0.0538 (14) Å for the O atom. The nitro group is twisted by 12.0 (3)° from the mean plane of the quinazolinone ring system. The crystal structure is stabilized by inter­molecular N—H⋯O, C—H⋯N and C—H⋯O hydrogen bonds

Uncertainty Analysis of Calibration Standards for On-wafer Measurements over 110 GHz

We present uncertainty analysis of calibration standards on a commercial calibration substrate for on-wafer S-parameter measurements over 110 GHz. At these frequencies, manufacturing tolerance is comparable to the sizes of calibration standards. Thus accurate knowledge about the actual dimensions of calibration standards becomes critical for system calibration and establishment of uncertainty budget. In this work, three different tools namely surfaceprofiler, optical interferometer, and Scanning Electron Microscope (SEM) have been used to measure calibration standards and investigate the effect of manufacturing tolerance on electrical parameters by using numerical software. Finally uncertainty of calibration standards will be given. In this work, we use three different techniques to characterise calibration standards and obtain manufacturing tolerance. And then numerical software is used to simulate how the electrical parameters are affected by the manufacturing imperfections. Finally uncertainty of the calibration is analysed

Electrical transport across metal/two-dimensional carbon junctions: Edge versus side contacts

Metal/two-dimensional carbon junctions are characterized by using a nanoprobe in an ultrahigh vacuum environment. Significant differences were found in bias voltage (V) dependence of differential conductance (dI/dV) between edge- and side-contact; the former exhibits a clear linear relationship (i.e., dI/dV \propto V), whereas the latter is characterized by a nonlinear dependence, dI/dV \propto V3/2. Theoretical calculations confirm the experimental results, which are due to the robust two-dimensional nature of the carbon materials under study. Our work demonstrates the importance of contact geometry in graphene-based electronic devices

Development of a Verification Technique for On-wafer Noise Figure Measurement Systems

We present the development of a verification technique for on-wafer noise figure (NF) measurement systems. As the key element of the technique, a verification device consisting of a mismatched attenuator and a low noise amplifier (LNA) has been developed. The attenuator and the LNA are fabricated on two separate chips but joined with a bondwire. The verification procedure based on the device has also been developed and tested on an on-wafer vector network analyzer system with a noise measurement option across the frequency range from 2 GHz to 20 GHz. It has also been found that the bondwire contributes to negligible effect on the system when NF is high e.g. 3 dB but slightly higher when NF is smaller e.g. 1 dB

Bandgap engineering of zigzag graphene nanoribbons by manipulating edge states via defective boundaries

One of severe limits of graphene nanoribbons (GNRs) in future applications is that zigzag GNRs (ZGNRs) are gapless, so cannot be used in field effect transistors (FETs). In this paper, using tight-binding approach and first principles method, we derived and proved a general edge (boundary) condition for the opening of a significant bandgap in ZGNRs with defective edge structures. The proposed semiconducting GNRs have some interesting properties including the one that they can be embedded and integrated in a large piece of graphene without the need of completely cutting them out. We also demonstrated a new type of high-performance all-ZGNR FET

Immediate Antiretroviral Therapy Decreases Mortality Among Patients With High CD4 Counts in China: A Nationwide, Retrospective Cohort Study.

BackgroundClinical trials have demonstrated that immediate initiation of antiretroviral therapy (ART) reduces AIDS-related morbidity and mortality. We tested the hypothesis that initiating ART ≤30 days after human immunodeficiency virus (HIV) diagnosis would be associated with reduced mortality among people living with HIV (PLWH) with CD4 counts >500 cells/μL.MethodsPLWH enrolled in the Chinese National HIV Information System between January 2012 and June 2014 with CD4 counts >500 cells/μL were followed for 12 months. Cox proportional hazards model was used to determine hazard ratios (HRs) for PLWH who initiated ART after HIV diagnosis. ART initiation was treated as a time-dependent variable.ResultsWe enrolled 34581 PLWH with CD4 >500 cells/μL; 1838 (5.3%) initiated ART ≤30 days after diagnosis (immediate ART group), and 19 deaths were observed with a mortality rate of 1.04 per 100 person-years (PY). Fifty-eight deaths were documented among the 5640 PLWH in the delayed ART group with a mortality rate of 2.25 per 100 PY. There were 713 deaths among the 27103 PLWH in the no ART group with a mortality rate of 2.39 per 100 PY. After controlling for potential confounding factors, ART initiation at ≤30 days (adjusted HR, 0.37 [95% confidence interval, .23-.58]) was a statistically significant protective factor.ConclusionsWe found that immediate ART is associated with a 63% reduction in overall mortality among PLWH with CD4 counts >500 cells/μL in China, supporting the recommendation to initiate ART immediately following HIV diagnosis