Oscillation-based DFT for Second-order Bandpass OTA-C Filters

This document is the Accepted Manuscript version. Under embargo until 6 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s00034-017-0648-9.This paper describes a design for testability technique for second-order bandpass operational transconductance amplifier and capacitor filters using an oscillation-based test topology. The oscillation-based test structure is a vectorless output test strategy easily extendable to built-in self-test. The proposed methodology converts filter under test into a quadrature oscillator using very simple techniques and measures the output frequency. Using feedback loops with nonlinear block, the filter-to-oscillator conversion techniques easily convert the bandpass OTA-C filter into an oscillator. With a minimum number of extra components, the proposed scheme requires a negligible area overhead. The validity of the proposed method has been verified using comparison between faulty and fault-free simulation results of Tow-Thomas and KHN OTA-C filters. Simulation results in 0.25μm CMOS technology show that the proposed oscillation-based test strategy for OTA-C filters is suitable for catastrophic and parametric faults testing and also effective in detecting single and multiple faults with high fault coverage.Peer reviewedFinal Accepted Versio

Proportional hazards models with continuous marks

For time-to-event data with finitely many competing risks, the proportional hazards model has been a popular tool for relating the cause-specific outcomes to covariates [Prentice et al. Biometrics 34 (1978) 541--554]. This article studies an extension of this approach to allow a continuum of competing risks, in which the cause of failure is replaced by a continuous mark only observed at the failure time. We develop inference for the proportional hazards model in which the regression parameters depend nonparametrically on the mark and the baseline hazard depends nonparametrically on both time and mark. This work is motivated by the need to assess HIV vaccine efficacy, while taking into account the genetic divergence of infecting HIV viruses in trial participants from the HIV strain that is contained in the vaccine, and adjusting for covariate effects. Mark-specific vaccine efficacy is expressed in terms of one of the regression functions in the mark-specific proportional hazards model. The new approach is evaluated in simulations and applied to the first HIV vaccine efficacy trial.Comment: Published in at http://dx.doi.org/10.1214/07-AOS554 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

On Schr\"odinger equations involving the regional fractional Laplacian in a ball with the zero boundary condition

Our purpose in this article to show the existence of positive classical solutions of $$( - \Delta )_{B_1}^s u +u=h_1 u^p+\epsilon h_2 \quad {\rm in} \ \, B_1,\qquad u = 0 \quad {\rm on}\ \partial B_1$$ for $\epsilon>0$ small enough, where $( - \Delta )_{B_1}^s$ is the regional fractional Laplacian, $p>1$, $h_i$ with $i=1,2$ are H\"older continuous and satisfy some additional conditions. Our existence is based on the solution of $$( - \Delta )_{B_1}^s u +u=1 \quad {\rm in} \ \, B_1,\qquad u = 0 \quad {\rm on}\ \partial B_1.$$Comment: 2

Knowledge building and vocabulary growth over two years, Grades 3 and 4

High-level literacy and productive knowledge work are central to educational reforms. In the research reported in this article, students were engaged in sustained, collaborative knowledge building in science and social studies. The vocabulary growth of 22 students over Grades 3 and 4 was traced, based on their entries to Knowledge Forum—a knowledge building environment used as an integral part of classroom work. It is the communal space where ideas, reference material, results of experiments, and other inquiry work are entered and continually improved. Analysis of lexical frequency profiles indicated significant growth in productive written vocabulary, including academic words. In a Grade 4 inquiry, students incorporated almost all the domain-specific terms at and below their current grade level, and most of those expected for upper grade levels (5-8) based on the curriculum guidelines. Domain-specific and academic words were correlated with depth of understanding. High correlations between student engagement in knowledge building and vocabulary growth suggest that productive vocabulary can be developed through sustained knowledge building in subject areas

Developing Deep Understanding and Literacy while Addressing a Gender-Based Literacy Gap

Online discourse from a class of 22 students (11 boys and 11 girls) was analysed to assess advances in conceptual understanding and literacy. The students worked over a two-­‐year period (Grades 3-­‐4), during which they contributed notes to an online Knowledge Building environment—Knowledge Forum®. Contributions revealed that both boys and girls produced a substantial amount of text and graphics, and that their written texts incorporated an increasing proportion of less-­‐frequent, advanced words, including academic vocabulary and domain-­‐specific words from grade levels higher than their own. Brief accounts of classroom discourse indicate how deep understanding and vocabulary growth mutually support each other in online and offline exchanges. The gender differences that were observed show boys doing slightly better than girls, suggesting that Knowledge Building has the potential to help boys overcome weaknesses in literacy

The Two-sample Problem for Failure Rates Depending on a Continuous Mark: An Application to Vaccine Efficacy

The efficacy of an HIV vaccine to prevent infection is likely to depend on the genetic variation of the exposing virus. This paper addresses the problem of using data on the HIV sequences that infect vaccine efficacy trial participants to 1) test for vaccine efficacy more powerfully than procedures that ignore the sequence data; and 2) evaluate the dependence of vaccine efficacy on the divergence of infecting HIV strains from the HIV strain that is contained in the vaccine. Because hundreds of amino acid sites in each HIV genome are sequenced, it is natural to treat the divergence (defined in terms of Hamming distance say) as a continuous mark variable that accompanies each failure (infection) time. Problems 1) and 2) can then be approached by testing whether the ratio of the mark-specific hazard functions for the vaccine and placebo groups is unity or independent of the mark, respectively. We develop nonparametric and semiparametric tests for these null hypotheses, based on contrasts of Nelson–Aalen-type estimates of cumulative mark-specific hazard functions for the two groups. Techniques for nonparametric estimation of mark-specific vaccine efficacy based on the cumulative mark-specific incidence functions are also developed. Numerical studies show satisfactory performance of the procedures. The methods are illustrated with application to HIV genetic sequence data collected in the first HIV vaccine efficacy trial. The methodology applies generally to the study of relative risks of failure wherein a continuous mark variable accompanies each failure event

Tests for Comparing Mark-Specific Hazards and Cumulative Incidence Functions

It is of interest in some applications to determine whether there is a relationship between a hazard rate function (or a cumulative incidence function) and a mark variable which is only observed at uncensored failure times. We develop nonparametric tests for this problem when the mark variable is continuous. Tests are developed for the null hypothesis that the mark-specific hazard rate is independent of the mark versus ordered and two-sided alternatives expressed in terms of mark-specific hazard functions and mark-specific cumulative incidence functions. The test statistics are based on functionals of a bivariate test process equal to a weighted average of differences between a Nelson--Aalen-type estimator of the mark-specific cumulative hazard function and a nonparametric estimator of this function under the null hypothesis. The weight function in the test process can be chosen so that the test statistics are asymptotically distribution-free.Asymptotically correct critical values are obtained through a simple simulation procedure. The testing procedures are shown to perform well in numerical studies, and are illustrated with an AIDS clinical trial example. Specifically, the tests are used to assess if the instantaneous or absolute risk of treatment failure depends on the amount of accumulation of drug resistance mutations in a subject\u27s HIV virus. This assessment helps guide development of anti-HIV therapies that surmount the problem of drug resistance

Herb-resistant UPEC strains have different biofilm formation abilities and different expression of certain biofilm related genes

Background: The mechanisms and patterns of drug resistances of E. coli strains that cause uncomplicated urinary tract infections (UTIs) vary considerably. The emerging herbresistance of uropathogenic Escherichia coli (UPEC) has been a serious health problem, yet with unknown underlying mechanisms.Methods: To explore the potential herb-resistance mechanisms of E. coli strains that cause uncomplicated UTIs, three clinically isolated herb-resistant UPEC strains (1351, 4996, 5028) were analyzed for their abilities to form biofilms and the expressions of the pga ABCD and luxS genes.Results: We found that the expression of pgaA and pgaB are very different between 1351 and 5028, and the loss-offunction of luxS in 4996 has impact on biofilm formation.Conclusions: 1. Herb-resistance of the strains is related to their abilities of biofilm formation. 2. Biofilm formation capabilities of herb-resistant strains show different responses to the presence of glucose. 3. luxS encoded AI-2 is not essential for biofilm formation in this strain but may help with more biofilm formation.Keywords: Herb-resistance; Biofilm formation; Uropathogenic Escherichia coli (UPEC); pga ABCD; lux