A block-diagonal structured model reduction scheme for power grid networks

We propose a block-diagonal structured model order reduction (BDSM) scheme for fast power grid analysis. Compared with existing power grid model order reduction (MOR) methods, BDSM has several advantages. First, unlike many power grid reductions that are based on terminal reduction and thus error-prone, BDSM utilizes an exact column-by-column moment matching to provide higher numerical accuracy. Second, with similar accuracy and macromodel size, BDSM generates very sparse block-diagonal reduced-order models (ROMs) for massive-port systems at a lower cost, whereas traditional algorithms such as PRIMA produce full dense models inefficient for the subsequent simulation. Third, different from those MOR schemes based on extended Krylov subspace (EKS) technique, BDSM is input-signal independent, so the resulting ROM is reusable under different excitations. Finally, due to its blockdiagonal structure, the obtained ROM can be simulated very fast. The accuracy and efficiency of BDSM are verified by industrial power grid benchmarks. © 2011 EDAA.published_or_final_versionDesign, Automation and Test in Europe Conference and Exhibition (DATE 2011), Grenoble, France, 14-18 March 2011. In Design, Automation, and Test in Europe Conference and Exhibition Proceedings, 2011, p. 44-4

Sequence Variations of Full-Length Hepatitis B Virus Genomes in Chinese Patients with HBsAg-Negative Hepatitis B Infection

BACKGROUND: The underlying mechanism of HBsAg-negative hepatitis B virus (HBV) infection is notoriously difficult to elucidate because of the extremely low DNA levels which define the condition. We used a highly efficient amplification method to overcome this obstacle and achieved our aim which was to identify specific mutations or sequence variations associated with this entity. METHODS: A total of 185 sera and 60 liver biopsies from HBsAg-negative, HBV DNA-positive subjects or known chronic hepatitis B (CHB) subjects with HBsAg seroclearance were amplified by rolling circle amplification followed by full-length HBV genome sequencing. Eleven HBsAg-positive CHB subjects were included as controls. The effects of pivotal mutations identified on regulatory regions on promoter activities were analyzed. RESULTS: 22 and 11 full-length HBV genomes were amplified from HBsAg-negative and control subjects respectively. HBV genotype C was the dominant strain. A higher mutation frequency was observed in HBsAg-negative subjects than controls, irrespective of genotype. The nucleotide diversity over the entire HBV genome was significantly higher in HBsAg-negative subjects compared with controls (p = 0.008) and compared with 49 reference sequences from CHB patients (p = 0.025). In addition, HBsAg-negative subjects had significantly higher amino acid substitutions in the four viral genes than controls (all p<0.001). Many mutations were uniquely found in HBsAg-negative subjects, including deletions in promoter regions (13.6%), abolishment of pre-S2/S start codon (18.2%), disruption of pre-S2/S mRNA splicing site (4.5%), nucleotide duplications (9.1%), and missense mutations in "alpha" determinant region, contributing to defects in HBsAg production. CONCLUSIONS: These data suggest an accumulation of multiple mutations constraining viral transcriptional activities contribute to HBsAg-negativity in HBV infection.published_or_final_versio

PEDS: Passivity enforcement for descriptor systems via Hamiltonian- symplectic matrix pencil perturbation

Passivity is a crucial property of macromodels to guarantee stable global (interconnected) simulation. However, weakly nonpassive models may be generated for passive circuits and systems in various contexts, such as data fitting, model order reduction (MOR) and electromagnetic (EM) macromodeling. Therefore, a post-processing passivity enforcement algorithm is desired. Most existing algorithms are designed to handle poleresidue models. The few algorithms for state space models only handle regular systems (RSs) with a nonsingular D+D T term. To the authors' best knowledge, no algorithm has been proposed to enforce passivity for more general descriptor systems (DSs) and state space models with singular D + D T terms. In this paper, a new post-processing passivity enforcement algorithm based on perturbation of Hamiltonian-symplectic matrix pencil, PEDS, is proposed. PEDS, for the first time, can enforce passivity for DSs. It can also handle all kinds of state space models (both RSs and DSs) with singular D + D T terms. Moreover, a criterion to control the error of perturbation is devised, with which the optimal passive models with the best accuracy can be obtained. Numerical examples then verify that PEDS is efficient, robust and relatively cheap for passivity enforcement of DSs with mild passivity violations. ©2010 IEEE.published_or_final_versionThe IEEE/ACM International Conference on Computer-Aided Design (ICCAD 2010), San Jose, CA., 7-11 November 2010. In Proceedings of ICCAD, 2010, p. 800-80

A Latent Class Growth Analysis Of School Bullying And Its Social Context: The Self-determination Theory Perspective

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On Sparse Vector Recovery Performance in Structurally Orthogonal Matrices via LASSO

In this paper, we consider the compressed sensing problem of reconstructing a sparse signal from an undersampled set of noisy linear measurements. The regularized least squares or least absolute shrinkage and selection operator (LASSO) formulation is used for signal estimation. The measurement matrix is assumed to be constructed by concatenating several randomly orthogonal bases, which we refer to as structurally orthogonal matrices. Such measurement matrix is highly relevant to large-scale compressive sensing applications because it facilitates rapid computation and parallel processing. Using the replica method in statistical physics, we derive the mean-squared-error (MSE) formula of reconstruction over the structurally orthogonal matrix in the large-system regime. Extensive numerical experiments are provided to verify the analytical result. We then consider the analytical result to investigate the MSE behaviors of the LASSO over the structurally orthogonal matrix, with an emphasis on performance comparisons with matrices with independent and identically distributed (i.i.d.) Gaussian entries. We find that structurally orthogonal matrices are at least as good as their i.i.d. Gaussian counterparts. Thus, the use of structurally orthogonal matrices is attractive in practical applications

Metastasis dormancy in estrogen receptor-positive breast cancer.

About 20% to 40% of patients with breast cancer eventually develop recurrences in distant organs, which are often not detected until years to decades after the primary tumor diagnosis. This phenomenon is especially pronounced in estrogen receptor-positive (ER(+)) breast cancer, suggesting that ER(+) cancer cells may stay dormant for a protracted period of time, despite adjuvant therapies. Multiple mechanisms have been proposed to explain how cancer cells survive and remain in dormancy, and how they become reactivated and exit dormancy. These mechanisms include angiogenic switch, immunosurveillance, and interaction with extracellular matrix and stromal cells. How to eradicate or suppress these dormant cancer cells remains a major clinical issue because of the lack of knowledge about the biologic and clinical nature of these cells. Herein, we review the clinical manifestation of metastasis dormancy in ER(+) tumors, the current biologic insights regarding tumor dormancy obtained from various experimental models, and the clinical challenges to predict, detect, and treat dormant metastases. We also discuss future research directions toward a better understanding of the biologic mechanisms and clinical management of ER(+) dormant metastasis

Differential contribution of psycholinguistic and cognitive skills to written composition in Chinese as a second language

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.This study examined the contribution of the constructs of orthographic processing (orthographic choice and orthographic choice in context), syntactic processing (grammaticality and sentence integrity), and verbal working memory (two reading span indicators) to written Chinese composition (narration, explanation, and argumentation) in 129 fifteen-year-old L2 learners. A matrix task was also administered as a control task to tap cognitive flexibility. Structural Equation Modeling (SEM) analysis with written composition as a latent variable revealed orthographic processing and working memory as two significant, independent contributors, whereas the unique contribution of syntactic processing was not significant. Subsequent SEM analysis with narration, explanation, and argumentation as separate endogenous variables found varied patterns of the contribution of each latent predictor to written composition in different genres. These patterns are discussed in light of the importance of attention to learners’ developmental stage and genre-sensitive measures to capture the psycholinguistic and cognitive underpinnings of written composition in L2 Chinese

Passivity enforcement for descriptor systems via matrix pencil perturbation

Passivity is an important property of circuits and systems to guarantee stable global simulation. Nonetheless, nonpassive models may result from passive underlying structures due to numerical or measurement error/inaccuracy. A postprocessing passivity enforcement algorithm is therefore desirable to perturb the model to be passive under a controlled error. However, previous literature only reports such passivity enforcement algorithms for pole-residue models and regular systems (RSs). In this paper, passivity enforcement algorithms for descriptor systems (DSs, a superset of RSs) with possibly singular direct term (specifically, D+D T or I-DD T) are proposed. The proposed algorithms cover all kinds of state-space models (RSs or DSs, with direct terms being singular or nonsingular, in the immittance or scattering representation) and thus have a much wider application scope than existing algorithms. The passivity enforcement is reduced to two standard optimization problems that can be solved efficiently. The objective functions in both optimization problems are the error functions, hence perturbed models with adequate accuracy can be obtained. Numerical examples then verify the efficiency and robustness of the proposed algorithms. © 2012 IEEE.published_or_final_versio

A Simple and Efficient Way to Combine Microcontrollers with RSA Cryptography

Microcontroller can be easily adopted in various applications with a variety of peripherals due to its merits of small size, simple architecture and etc. However, the limited computing power restricts its application in cryptography. In this paper, we try to integrate microcontroller with different peripheral devices to support more powerful cryptography computation in a simple and efficient way. Based on the most popular open source microcontroller development platform, Arduino, we design and develop a cryptographic hardware device for a real-life application which provides data protection functions for authority and integrity with RSA cryptography supported. With the peripherals Java card, our Arduino-cored solution is able to efficiently generate digital signature of photos taken by smart phone using the asymmetric cryptographic algorithm, RSA, which has a poor performance if it is directly implemented on microcontroller. The experimental results show that the device can finish a RSA 1024-bit encryption in 82.2 microseconds, which is reasonable in real application scenario and illustrates the feasibility of implementing more complicated cryptographic system using microcontroller.published_or_final_versio