454 results on '"Helen Zhang"'
Search Results
202. Analysis of Gene Expression at Proteomic Level via Western Blotting
- Author
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Michael J. Welsh, Helen Zhang, William Wu, and Peter B. Kaufman
- Subjects
Blot ,Chemistry ,Gene expression ,Molecular biology - Published
- 2016
203. Quantitative Analysis of Functional Genome by Real-Time RT-PCR
- Author
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William Wu, Michael J. Welsh, Peter Kaufman, and Helen Zhang
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Real-time polymerase chain reaction ,Computational biology ,Biology ,Quantitative analysis (chemistry) ,Genome - Published
- 2016
204. Construction and Screening of Human Antibody Libraries Using Phage Display Technology
- Author
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Helen Zhang, Peter Kaufman, Michael J. Welsh, and William Wu
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Phage display ,biology ,biology.protein ,Antibody ,Virology - Published
- 2016
205. Gene Overexpression by Sense RNA in Mammalian Systems
- Author
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Michael J. Welsh, William Wu, Helen Zhang, and Peter Kaufman
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Genetics ,RNA silencing ,Chemistry ,Sense (molecular biology) ,RNA ,Gene - Published
- 2016
206. Improving performance of nanoscale ultrasound contrast agents using N,N-diethylacrylamide stabilization
- Author
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Pubudu M. Peiris, Christopher Hernandez, Hanping Wu, Alan Burke, Agata A. Exner, Reshani Perera, and Helen Zhang
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Materials science ,Polymers ,Biomedical Engineering ,Pharmaceutical Science ,Medicine (miscellaneous) ,Nanoparticle ,Contrast Media ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,Mice ,Drug Delivery Systems ,Pulmonary surfactant ,Cell Line, Tumor ,Animals ,Humans ,General Materials Science ,Lipid bilayer ,Ultrasonography ,Acrylamides ,Microbubbles ,business.industry ,Ultrasound ,Echogenicity ,021001 nanoscience & nanotechnology ,Xenograft Model Antitumor Assays ,0104 chemical sciences ,Drug delivery ,Molecular Medicine ,Nanoparticles ,Molecular imaging ,0210 nano-technology ,business ,Colorectal Neoplasms ,Biomedical engineering - Abstract
The design of nanoscale yet highly echogenic agents for imaging outside of the vasculature and for ultrasound-mediated drug delivery remains a formidable challenge. We have previously reported on formulation of echogenic perfluoropropane gas nanobubbles stabilized by a lipid-Pluronic surfactant shell. In the current work we describe the development of a new generation of these nanoparticles which consist of perfluoropropane gas stabilized by a surfactant and lipid membrane and a crosslinked network of N, N-diethylacrylamide. The resulting crosslinked nanobubbles (CL-PEG-NB) were 95.2 ± 25.2 nm in diameter and showed significant improvement in stability and retention of echogenic signal over 24 h. In vivo analysis via ultrasound and fluorescence mediated tomography showed greater tumor extravasation and accumulation with CL-PEG-NB compared to microbubbles. Together these results demonstrate the capabilities and advantages of a new, more stable, nanometer-scale ultrasound contrast agent that can be utilized in future work for diagnostic scans and molecular imaging.
- Published
- 2016
207. Evaluating IPMN and pancreatic carcinoma utilizing quantitative histopathology
- Author
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Michael Yozwiak, Joseph C. Watkins, Evan S. Glazer, Kimberly A. Hill, Hao Helen Zhang, Charmi Patel, David S. Alberts, Stephanie T. Kha, Hubert G. Bartels, Robert S. Krouse, and Nellie N. Nafissi
- Subjects
Adult ,Male ,Cancer Research ,medicine.medical_specialty ,quantitative histopathology ,endocrine system diseases ,Library science ,Quantitative histopathology ,Intraductal papillary mucinous neoplasms ,Diagnosis, Differential ,03 medical and health sciences ,0302 clinical medicine ,Medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Pancreatic carcinoma ,nuclear chromatin pattern ,Aged ,Original Research ,Aged, 80 and over ,pancreatic carcinoma ,business.industry ,Clinical Cancer Research ,Middle Aged ,Adenocarcinoma, Mucinous ,Carcinoma, Papillary ,3. Good health ,Surgery ,Pancreatic Neoplasms ,Oncology ,030220 oncology & carcinogenesis ,karyometry ,030211 gastroenterology & hepatology ,Female ,business ,Carcinoma, Pancreatic Ductal - Abstract
Intraductal papillary mucinous neoplasms (IPMN) are pancreatic lesions with uncertain biologic behavior. This study sought objective, accurate prediction tools, through the use of quantitative histopathological signatures of nuclear images, for classifying lesions as chronic pancreatitis (CP), IPMN, or pancreatic carcinoma (PC). Forty‐four pancreatic resection patients were retrospectively identified for this study (12 CP; 16 IPMN; 16 PC). Regularized multinomial regression quantitatively classified each specimen as CP, IPMN, or PC in an automated, blinded fashion. Classification certainty was determined by subtracting the smallest classification probability from the largest probability (of the three groups). The certainty function varied from 1.0 (perfectly classified) to 0.0 (random). From each lesion, 180 ± 22 nuclei were imaged. Overall classification accuracy was 89.6% with six unique nuclear features. No CP cases were misclassified, 1/16 IPMN cases were misclassified, and 4/16 PC cases were misclassified. Certainty function was 0.75 ± 0.16 for correctly classified lesions and 0.47 ± 0.10 for incorrectly classified lesions (P = 0.0005). Uncertainty was identified in four of the five misclassified lesions. Quantitative histopathology provides a robust, novel method to distinguish among CP, IPMN, and PC with a quantitative measure of uncertainty. This may be useful when there is uncertainty in diagnosis.
- Published
- 2016
208. Joint structure selection and estimation in the time-varying coefficient Cox model
- Author
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Hao Helen Zhang, Wenbin Lu, and Wei Xiao
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0301 basic medicine ,Statistics and Probability ,Proportional hazards model ,Model selection ,Estimator ,01 natural sciences ,Article ,010104 statistics & probability ,03 medical and health sciences ,030104 developmental biology ,Null (SQL) ,Linear regression ,Statistics ,Covariate ,0101 mathematics ,Statistics, Probability and Uncertainty ,Constant (mathematics) ,Selection (genetic algorithm) ,Mathematics - Abstract
Time-varying coefficient Cox model has been widely studied and popularly used in survival data analysis due to its flexibility for modeling covariate effects. It is of great practical interest to accurately identify the structure of covariate effects in a time-varying coefficient Cox model, i.e. covariates with null effect, constant effect and truly time-varying effect, and estimate the corresponding regression coefficients. Combining the ideas of local polynomial smoothing and group nonnegative garrote, we develop a new penalization approach to achieve such goals. Our method is able to identify the underlying true model structure with probability tending to one and simultaneously estimate the time-varying coefficients consistently. The asymptotic normalities of the resulting estimators are also established. We demonstrate the performance of our method using simulations and an application to the primary biliary cirrhosis data.
- Published
- 2016
209. Chinese Cultural Kaleidoscope
- Author
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Yuehong (Helen) Zhang
- Published
- 2016
210. Against Plagiarism
- Author
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Yuehong (Helen) Zhang
- Published
- 2016
211. Time-Varying Latent Effect Model for Longitudinal Data with Informative Observation Times
- Author
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Na Cai, Hao Helen Zhang, and Wenbin Lu
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Statistics and Probability ,Biometry ,Computer science ,Information Storage and Retrieval ,Estimating equations ,Latent variable ,Article ,General Biochemistry, Genetics and Molecular Biology ,Matrix (mathematics) ,Statistics ,Statistical inference ,Applied mathematics ,Computer Simulation ,Longitudinal Studies ,Models, Statistical ,General Immunology and Microbiology ,Estimation theory ,Applied Mathematics ,Estimator ,General Medicine ,Zero (linguistics) ,Data Interpretation, Statistical ,Epidemiologic Methods ,General Agricultural and Biological Sciences ,Constant (mathematics) ,Algorithms - Abstract
In analysis of longitudinal data, it is not uncommon that observation times of repeated measurements are subject-specific and correlated with underlying longitudinal outcomes. Taking account of the dependence between observation times and longitudinal outcomes is critical under these situations to assure the validity of statistical inference. In this article, we propose a flexible joint model for longitudinal data analysis in the presence of informative observation times. In particular, the new procedure considers the shared random-effect model and assume a time-varying coefficient for the latent variable, allowing a flexible way of modeling longitudinal outcomes while adjusting their association with observation times. Estimating equations are developed for parameter estimation. We show that the resulting estimators are consistent and asymptotically normal, with variance-covariance matrix that has a closed form and can be consistently estimated by the usual plug-in method. One additional advantage of the procedure is that, it provides a unified framework to test whether the effect of the latent variable is zero, constant, or time-varying. Simulation studies show that the proposed approach is appropriate for practical use. An application to a bladder cancer data is also given to illustrate the methodology.
- Published
- 2012
212. Variable selection for covariate-adjusted semiparametric inference in randomized clinical trials
- Author
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Marie Davidian, Hao Helen Zhang, and Shuai Yuan
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Statistics and Probability ,Selection bias ,Analysis of covariance ,Models, Statistical ,Epidemiology ,media_common.quotation_subject ,Inference ,Context (language use) ,Feature selection ,Statistics, Nonparametric ,Article ,Standard error ,Research Design ,Covariate ,Statistics ,Econometrics ,Humans ,Algorithms ,Selection Bias ,Selection (genetic algorithm) ,Randomized Controlled Trials as Topic ,media_common ,Mathematics - Abstract
Extensive baseline covariate information is routinely collected on participants in randomized clinical trials, and it is well recognized that a proper covariate-adjusted analysis can improve the efficiency of inference on the treatment effect. However, such covariate adjustment has engendered considerable controversy, as post hoc selection of covariates may involve subjectivity and may lead to biased inference, whereas prior specification of the adjustment may exclude important variables from consideration. Accordingly, how to select covariates objectively to gain maximal efficiency is of broad interest. We propose and study the use of modern variable selection methods for this purpose in the context of a semiparametric framework, under which variable selection in modeling the relationship between outcome and covariates is separated from estimation of the treatment effect, circumventing the potential for selection bias associated with standard analysis of covariance methods. We demonstrate that such objective variable selection techniques combined with this framework can identify key variables and lead to unbiased and efficient inference on the treatment effect. A critical issue in finite samples is validity of estimators of uncertainty, such as standard errors and confidence intervals for the treatment effect. We propose an approach to estimation of sampling variation of estimated treatment effect and show its superior performance relative to that of existing methods. Copyright © 2012 John Wiley & Sons, Ltd.
- Published
- 2012
213. Can generating representations enhance learning with dynamic visualizations?
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Zhihui Helen Zhang and Marcia C. Linn
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Multimedia ,Hydrogen combustion ,Energy (esotericism) ,computer.software_genre ,Science education ,Education ,Visualization ,Molecular level ,Human–computer interaction ,Dynamic visualization ,Curriculum development ,Chemistry (relationship) ,Psychology ,computer - Abstract
This study explores the impact of asking middle school students to generate drawings of their ideas about chemical reactions on integrated understanding. Students explored atomic interactions during hydrogen combustion using a dynamic visualization. The generation group drew their ideas about how the reaction takes place at the molecular level. The interaction group conducted multiple experiments with the visualization by varying the amount of energy provided to ignite the reaction. The generation group integrated more ideas about chemical reactions and made more precise interpretations of the visualization than the interaction group. Embedded assessments show that generation motivated students to interpret the visualization carefully and led to more productive explanations about ideas represented in the dynamic visualization. In contrast, the interaction group was less successful in linking the visualization to underlying concepts and observable phenomena and wrote less detailed explanations. The study suggests that drawing is a promising way to help students interpret complex visualizations and integrate information. 2011 Wiley Periodicals, Inc. J Res Sci Teach 48: 1177-1198, 2011
- Published
- 2011
214. Multiple Forms of Activity-Dependent Competition Refine Hippocampal Circuits In Vivo
- Author
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Jack M. Parent, Hisashi Umemori, Helen Zhang, Erin M. Johnson-Venkatesh, Masahiro Yasuda, and Michael A. Sutton
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Neurogenesis ,Neuroscience(all) ,Neural Inhibition ,Hippocampus ,Mice, Transgenic ,Hippocampal formation ,Biology ,Article ,Mice ,Memory ,Neuroplasticity ,Neural Pathways ,medicine ,Animals ,Entorhinal Cortex ,Gene Silencing ,Axon ,Cellular Senescence ,Neurons ,Neuronal Plasticity ,General Neuroscience ,Dentate gyrus ,Axons ,medicine.anatomical_structure ,nervous system ,Dentate Gyrus ,Neuroscience ,Cell aging - Abstract
SummaryEfficient memory formation relies on the establishment of functional hippocampal circuits. It has been proposed that synaptic connections are refined by neural activity to form functional brain circuitry. However, it is not known whether and how hippocampal connections are refined by neural activity in vivo. Using a mouse genetic system in which restricted populations of neurons in the hippocampal circuit are inactivated, we show that inactive axons are eliminated after they develop through a competition with active axons. Remarkably, in the dentate gyrus, which undergoes neurogenesis throughout life, axon refinement is achieved by a competition between mature and young neurons. These results demonstrate that activity-dependent competition plays multiple roles in the establishment of functional memory circuits in vivo.
- Published
- 2011
- Full Text
- View/download PDF
215. Hard or Soft Classification? Large-Margin Unified Machines
- Author
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Hao Helen Zhang, Yufeng Liu, and Yichao Wu
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Statistics and Probability ,business.industry ,Conditional probability ,Fisher consistency ,Linear discriminant analysis ,Machine learning ,computer.software_genre ,Class (biology) ,Article ,Support vector machine ,Random subspace method ,ComputingMethodologies_PATTERNRECOGNITION ,Margin (machine learning) ,Statistics ,Decision boundary ,Artificial intelligence ,Statistics, Probability and Uncertainty ,business ,computer ,Mathematics - Abstract
Margin-based classifiers have been popular in both machine learning and statistics for classification problems. Among numerous classifiers, some are hard classifiers while some are soft ones. Soft classifiers explicitly estimate the class conditional probabilities and then perform classification based on estimated probabilities. In contrast, hard classifiers directly target on the classification decision boundary without producing the probability estimation. These two types of classifiers are based on different philosophies and each has its own merits. In this paper, we propose a novel family of large-margin classifiers, namely large-margin unified machines (LUMs), which covers a broad range of margin-based classifiers including both hard and soft ones. By offering a natural bridge from soft to hard classification, the LUM provides a unified algorithm to fit various classifiers and hence a convenient platform to compare hard and soft classification. Both theoretical consistency and numerical performance of LUMs are explored. Our numerical study sheds some light on the choice between hard and soft classifiers in various classification problems.
- Published
- 2011
216. Bayesian Inference of Odds Ratios in Misclassified Binary Data with a Validation Substudy
- Author
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Hao Helen Zhang, Dewi Rahardja, and Yan D. Zhao
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Statistics and Probability ,Bayesian statistics ,Frequentist inference ,Modeling and Simulation ,Statistics ,Bayesian experimental design ,Fiducial inference ,Statistical inference ,Bayesian hierarchical modeling ,Bayesian linear regression ,Bayesian inference ,Mathematics - Abstract
We propose a fully Bayesian model with a non-informative prior for analyzing misclassified binary data with a validation substudy. In addition, we derive a closed-form algorithm for drawing all parameters from the posterior distribution and making statistical inference on odds ratios. Our algorithm draws each parameter from a beta distribution, avoids the specification of initial values, and does not have convergence issues. We apply the algorithm to a data set and compare the results with those obtained by other methods. Finally, the performance of our algorithm is assessed using simulation studies.
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- 2010
217. On Estimation of Partially Linear Transformation Models
- Author
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Hao Helen Zhang and Wenbin Lu
- Subjects
Statistics and Probability ,Iterative method ,Kernel density estimation ,Linear model ,Article ,Delta method ,Nonlinear system ,Kernel method ,Statistics ,Covariate ,Applied mathematics ,Statistics, Probability and Uncertainty ,Mathematics ,Parametric statistics - Abstract
We study a general class of partially linear transformation models, which extend linear transformation models by incorporating nonlinear covariate effects in survival data analysis. A new martingale-based estimating equation approach, consisting of both global and kernel-weighted local estimation equations, is developed for estimating the parametric and nonparametric covariate effects in a unified manner. We show that with a proper choice of the kernel bandwidth parameter, one can obtain the consistent and asymptotically normal parameter estimates for the linear effects. Asymptotic properties of the estimated nonlinear effects are established as well. We further suggest a simple resampling method to estimate the asymptotic variance of the linear estimates and show its effectiveness. To facilitate the implementation of the new procedure, an iterative algorithm is developed. Numerical examples are given to illustrate the finite-sample performance of the procedure. Supplementary materials are available online.
- Published
- 2010
218. The Developmental Stage of Dentate Granule Cells Dictates Their Contribution to Seizure-Induced Plasticity
- Author
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Michelle M. Kron, Helen Zhang, and Jack M. Parent
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Male ,Neurogenesis ,Status epilepticus ,Hippocampal formation ,Biology ,Epileptogenesis ,Rats, Sprague-Dawley ,Status Epilepticus ,Cell Movement ,Seizures ,Neuroplasticity ,medicine ,Animals ,Neuronal Plasticity ,Stem Cells ,General Neuroscience ,Dentate gyrus ,Dendrites ,Articles ,Granule cell ,Rats ,medicine.anatomical_structure ,Epilepsy, Temporal Lobe ,Dentate Gyrus ,Mossy Fibers, Hippocampal ,Stem cell ,medicine.symptom ,Neuroscience ,Cell Division - Abstract
Dentate granule cell (DGC) neurogenesis persists throughout life in the hippocampal dentate gyrus. In rodent temporal lobe epilepsy models, status epilepticus (SE) stimulates neurogenesis, but many newborn DGCs integrate aberrantly and are hyperexcitable, whereas others may integrate normally and restore inhibition. The overall influence of altered neurogenesis on epileptogenesis is therefore unclear. To better understand the role DGC neurogenesis plays in seizure-induced plasticity, we injected retroviral (RV) reporters to label dividing DGC progenitors at specific times before or after SE, or used x-irradiation to suppress neurogenesis. RV injections 7 weeks before SE to mark DGCs that had matured by the time of SE labeled cells with normal placement and morphology 4 weeks after SE. RV injections 2 or 4 weeks before seizure induction to label cells still developing during SE revealed normally located DGCs exhibiting hilar basal dendrites and mossy fiber sprouting (MFS) when observed 4 weeks after SE. Cells labeled by injecting RV after SE displayed hilar basal dendrites and ectopic migration, but not sprouting, at 28 d after SE; when examined 10 weeks after SE, however, these cells showed robust MFS. Eliminating cohorts of newborn DGCs by focal brain irradiation at specific times before or after SE decreased MFS or hilar ectopic DGCs, supporting the RV labeling results. These findings indicate that developing DGCs exhibit maturation-dependent vulnerability to SE, indicating that abnormal DGC plasticity derives exclusively from aberrantly developing DGCs. Treatments that restore normal DGC development after epileptogenic insults may therefore ameliorate epileptogenic network dysfunction and associated morbidities.
- Published
- 2010
219. Automatic model selection for partially linear models
- Author
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Hao Helen Zhang, Xiao Ni, and Daowen Zhang
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Shrinkage estimator ,Statistics and Probability ,Variable selection ,Smoothly clipped absolute deviation ,01 natural sciences ,Article ,010104 statistics & probability ,Smoothing spline ,0502 economics and business ,Statistics ,Statistics::Methodology ,Applied mathematics ,0101 mathematics ,050205 econometrics ,Mathematics ,Numerical Analysis ,Smoothing splines ,Model selection ,05 social sciences ,Linear model ,Semiparametric regression ,Estimator ,Efficient estimator ,Parametric model ,Statistics, Probability and Uncertainty ,Smoothing - Abstract
We propose and study a unified procedure for variable selection in partially linear models. A new type of double-penalized least squares is formulated, using the smoothing spline to estimate the nonparametric part and applying a shrinkage penalty on parametric components to achieve model parsimony. Theoretically we show that, with proper choices of the smoothing and regularization parameters, the proposed procedure can be as efficient as the oracle estimator [J. Fan, R. Li, Variable selection via nonconcave penalized likelihood and its oracle properties, Journal of American Statistical Association 96 (2001) 1348–1360]. We also study the asymptotic properties of the estimator when the number of parametric effects diverges with the sample size. Frequentist and Bayesian estimates of the covariance and confidence intervals are derived for the estimators. One great advantage of this procedure is its linear mixed model (LMM) representation, which greatly facilitates its implementation by using standard statistical software. Furthermore, the LMM framework enables one to treat the smoothing parameter as a variance component and hence conveniently estimate it together with other regression coefficients. Extensive numerical studies are conducted to demonstrate the effective performance of the proposed procedure.
- Published
- 2009
- Full Text
- View/download PDF
220. A new chi-square approximation to the distribution of non-negative definite quadratic forms in non-central normal variables
- Author
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Yongqiang Tang, Hao Helen Zhang, and Huan Liu
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Statistics and Probability ,Applied Mathematics ,Mathematical analysis ,Quadratic function ,Isotropic quadratic form ,Quadratic residuosity problem ,Definite quadratic form ,Computational Mathematics ,Computational Theory and Mathematics ,Quadratic form ,Binary quadratic form ,Quadratic field ,Quadratic programming ,Mathematics - Abstract
This note proposes a new chi-square approximation to the distribution of non-negative definite quadratic forms in non-central normal variables. The unknown parameters are determined by the first four cumulants of the quadratic forms. The proposed method is compared with Pearson's three-moment central @g^2 approximation approach, by means of numerical examples. Our method yields a better approximation to the distribution of the non-central quadratic forms than Pearson's method, particularly in the upper tail of the quadratic form, the tail most often needed in practical work.
- Published
- 2009
221. FIRST: Combining forward iterative selection and shrinkage in high dimensional sparse linear regression
- Author
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Hao Helen Zhang, Subhashis Ghosal, and Wook-Yeon Hwang
- Subjects
Statistics and Probability ,Elastic net regularization ,business.industry ,Applied Mathematics ,Linear model ,Estimator ,Feature selection ,Machine learning ,computer.software_genre ,Lasso (statistics) ,Linear regression ,Convergence (routing) ,Statistics::Methodology ,Artificial intelligence ,business ,computer ,Algorithm ,Selection (genetic algorithm) ,Mathematics - Abstract
We propose a new class of variable selection techniques for regression in high dimensional linear models based on a forward selection version of the LASSO, adaptive LASSO or elastic net, respectively to be called as forward iterative regression and shrinkage technique (FIRST), adaptive FIRST and elastic FIRST. These methods seem to work effectively for extremely sparse high dimensional linear models. We exploit the fact that the LASSO, adaptive LASSO and elastic net have closed form solutions when the predictor is onedimensional. The explicit formula is then repeatedly used in an iterative fashion to build the model until convergence occurs. By carefully considering the relationship between estimators at successive stages, we develop fast algorithms to compute our estimators. The performance of our new estimators are compared with commonly used estimators in terms of predictive accuracy and errors in variable selection. AMS 2000 subject classifications: Primary 62J05, 62J05; secondary 62J07.
- Published
- 2009
222. Role of LPA4/p2y9/GPR23 in Negative Regulation of Cell Motility
- Author
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Jinhua Wu, Helen Zhang, Jolene J. Windle, Zendra Lee, Xianjun Fang, Mark A. Subler, Ching-Kang Chen, Ching-Ting Cheng, and Abir Mukherjee
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Male ,Biology ,Endothelial cell differentiation ,Mice ,chemistry.chemical_compound ,Cell Movement ,Cell Line, Tumor ,Lysophosphatidic acid ,Animals ,Humans ,Protein Isoforms ,Neoplasm Invasiveness ,Tissue Distribution ,Receptors, Lysophosphatidic Acid ,Receptor ,Molecular Biology ,Protein kinase B ,Cells, Cultured ,Mice, Knockout ,Purinergic receptor ,Receptors, Purinergic ,Cell migration ,Articles ,Cell Biology ,Fibroblasts ,rac GTP-Binding Proteins ,Cell biology ,Enzyme Activation ,Rac GTP-Binding Proteins ,chemistry ,Colonic Neoplasms ,Female ,lipids (amino acids, peptides, and proteins) ,Lysophospholipids ,biological phenomena, cell phenomena, and immunity ,Signal transduction ,Proto-Oncogene Proteins c-akt ,Signal Transduction - Abstract
Lysophosphatidic acid (LPA) is a ligand of multiple G protein–coupled receptors. The LPA1–3receptors are members of the endothelial cell differentiation gene (Edg) family. LPA4/p2y9/GPR23, a member of the purinergic receptor family, and recently identified LPA5/GPR92 and p2y5 are structurally distant from the canonical Edg LPA receptors. Here we report targeted disruption of lpa4in mice. Although LPA4-deficient mice displayed no apparent abnormalities, LPA4-deficient mouse embryonic fibroblasts (MEFs) were hypersensitive to LPA-induced cell migration. Consistent with negative modulation of the phosphatidylinositol 3 kinase pathway by LPA4, LPA4deficiency potentiated Akt and Rac but decreased Rho activation induced by LPA. Reconstitution of LPA4converted LPA4-negative cells into a less motile phenotype. In support of the biological relevance of these observations, ectopic expression of LPA4strongly inhibited migration and invasion of human cancer cells. When coexpressed with LPA1in B103 neuroblastoma cells devoid of endogenous LPA receptors, LPA4attenuated LPA1-driven migration and invasion, indicating functional antagonism between the two subtypes of LPA receptors. These results provide genetic and biochemical evidence that LPA4is a suppressor of LPA-dependent cell migration and invasion in contrast to the motility-stimulating Edg LPA receptors.
- Published
- 2008
223. Machine, Industry and Manufacturing Based on Applied-Information Technology IV
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Bioengineering, Building, Building materials, Chemical engineering, Chemistry, Engineering, Environmental engineering, Highway engineering, Industrial engineering, Mechanical engineering, Physics, Railroad engineering, Science, Technology--Environmental aspects
- Abstract
Selected, peer reviewed papers from the 2014 4th International Conference on Mechanical Engineering, Industry and Manufacturing Engineering (MEIME 2014), October 25-26, 2014, Beijing, China
- Published
- 2014
224. Advanced Development of Engineering Science IV
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Engineering--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 4th International Conference on Automation, Communication, Architectonics and Materials (ACAM 2014) September 27-28, 2014, Wuhan, China
- Published
- 2014
225. Advanced Research on Material Engineering, Chemistry, Bioinformatics III
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Bioinformatics--Congresses, Materials--Congresses, Chemistry--Congresses
- Abstract
Selected, peer reviewed papers from the 2013 3rd International Conference on Material Engineering, Chemistry, Bioinformatics (MECB 2013), October 26-27, 2013, Hefei, China
- Published
- 2014
226. Materials Science, Environment Protection and Applied Research
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Materials science--Congresses, Environmental sciences--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 2nd International Conference on Environmental Science and Material Application (ESME 2014), March 22-23, 2014, Wuhan, China
- Published
- 2014
227. Advanced Research on Material Science, Environment Science and Computer Science III
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Bioengineering, Chemical engineering, Chemistry, Engineering, Environmental engineering, Mechanical engineering, Physics, Science, Technology--Environmental aspects
- Abstract
Selected, peer reviewed papers from the 2014 3rd International Conference on Material Science, Environment Science and Computer Science, (MSESCS 2014), January 11-12, 2014, Wuhan, China
- Published
- 2014
228. Advanced Research on Intelligent System, Mechanical Design Engineering and Information Engineering III
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Mechanical engineering--Congresses, Intelligent control systems--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 3rd International Conference on Intelligent Materials and Mechanical Engineering (MEE 2014), May 24-25, 2014, Guangzhou, China
- Published
- 2014
229. Advanced Research on Mechanics, Manufacturing Engineering and Applied Technology II
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Production engineering--Research--Congresses, Mechanical engineering--Research--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 2nd International Conference on Applied Mechanics and Manufacturing System (AMMS 2014), April 26-27, 2014, Zhengzhou, China
- Published
- 2014
230. Advanced Research on Mechanical and Electronic Information Engineering II
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Electrical engineering--Congresses, Mechanical engineering--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 2nd International Conference on Mechanical and Electronic Engineering (ICMEE 2014), June 21-22, 2014, Wuhan, China
- Published
- 2014
231. Advanced Research on Energy, Chemistry, Materials and Informatization III
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Materials science--Congresses, Mechanics, Applied--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 3rd International Conference on Energy Materials and Material Application (EMMA 2014), August 23-24, 2014, Wuhan, China
- Published
- 2014
232. Advanced Research on Information Science, Automation and Material System IV
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Information technology--Congresses, Materials--Congresses, Automatic control--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 4th International Conference on Information Science, Automation and Material System (ISAM 2014), August 23-24, 2014, Wuhan, China
- Published
- 2014
233. Advanced Research on Structure, Materials, Engineering and Information Technology III
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Information display systems--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 3rd International Conference on Advanced Structure, Materials and Engineering (ASME 2014), August 23-24, 2014, Wuhan, China
- Published
- 2014
234. Material Science, Engineering Research, Management and Information Technologies
- Author
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Helen Zhang, David Jin, X.J. Zhao, Helen Zhang, David Jin, and X.J. Zhao
- Subjects
- Power (Mechanics)--Congresses, Materials science--Congresses, Power resources--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 4th International Conference on Engineering Materials, Energy, Management and Control (MEMC 2014), June 21-22, 2014, Wuhan, China
- Published
- 2014
235. Advanced Research in Material Engineering, Machinery and Applied Technologies
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Building, Building materials, Chemical engineering, Chemistry, Engineering, Environmental engineering, Highway engineering, Mechanical engineering, Physics, Railroad engineering, Science, Technology--Environmental aspects
- Abstract
Selected, peer reviewed papers from the 2014 International Conference on Material Engineering, Energy and Applied Technology (MEEA 2014), November 29-30, 2014, Hefei, China
- Published
- 2014
236. Advanced Research on Industry, Information System and Material Engineering IV
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Technology--Congresses, Telecommunication--Congresses, Materials--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 4th International Conference on Industry, Information System and Material Engineering (IISME 2014), July 26-27, 2014, Nanjing, China
- Published
- 2014
237. Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- Author
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Helen Zhang, M. Han, X.J. Zhao, Helen Zhang, M. Han, and X.J. Zhao
- Subjects
- Insulating materials--Testing--Congresses
- Abstract
Selected, peer reviewed papers from the 2014 2nd International Conference on Insulating Materials, Material Application and Electrical Engineering (MAEE 2014), July 26-27, 2014, Nanjing, China
- Published
- 2014
238. Adaptive Lasso for Cox's proportional hazards model
- Author
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Wenbin Lu and Hao Helen Zhang
- Subjects
Statistics and Probability ,Mathematical optimization ,Applied Mathematics ,General Mathematics ,Model selection ,Estimator ,Feature selection ,Agricultural and Biological Sciences (miscellaneous) ,Lasso (statistics) ,Linear regression ,Convex optimization ,Statistics::Methodology ,Penalty method ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,Selection (genetic algorithm) ,Mathematics - Abstract
We investigate the variable selection problem for Cox's proportional hazards model, and propose a unified model selection and estimation procedure with desired theoretical properties and computational convenience. The new method is based on a penalized log partial likelihood with the adaptively weighted L 1 penalty on regression coefficients, providing what we call the adaptive Lasso estimator. The method incorporates different penalties for different coefficients: unimportant variables receive larger penalties than important ones, so that important variables tend to be retained in the selection process, whereas unimportant variables are more likely to be dropped. Theoretical properties, such as consistency and rate of convergence of the estimator, are studied. We also show that, with proper choice of regularization parameters, the proposed estimator has the oracle properties. The convex optimization nature of the method leads to an efficient algorithm. Both simulated and real examples show that the method performs competitively. Copyright 2007, Oxford University Press.
- Published
- 2007
239. Support vector machines with adaptive penalty
- Author
-
Yufeng Liu, Jeongyoun Ahn, Cheolwoo Park, and Hao Helen Zhang
- Subjects
Statistics and Probability ,Iterative method ,Applied Mathematics ,Feature selection ,Function (mathematics) ,Support vector machine ,Computational Mathematics ,Noise ,Computational Theory and Mathematics ,Hinge loss ,Penalty method ,Adaptive learning ,Algorithm ,Mathematics - Abstract
The standard support vector machine (SVM) minimizes the hinge loss function subject to the L"2 penalty or the roughness penalty. Recently, the L"1 SVM was suggested for variable selection by producing sparse solutions [Bradley, P., Mangasarian, O., 1998. Feature selection via concave minimization and support vector machines. In: Shavlik, J. (Ed.), ICML'98. Morgan Kaufmann, Los Altos, CA; Zhu, J., Hastie, T., Rosset, S., Tibshirani, R., 2003. 1-norm support vector machines. Neural Inform. Process. Systems 16]. These learning methods are non-adaptive since their penalty forms are pre-determined before looking at data, and they often perform well only in a certain type of situation. For instance, the L"2 SVM generally works well except when there are too many noise inputs, while the L"1 SVM is more preferred in the presence of many noise variables. In this article we propose and explore an adaptive learning procedure called the L"q SVM, where the best q>0 is automatically chosen by data. Both two- and multi-class classification problems are considered. We show that the new adaptive approach combines the benefit of a class of non-adaptive procedures and gives the best performance of this class across a variety of situations. Moreover, we observe that the proposed L"q penalty is more robust to noise variables than the L"1 and L"2 penalties. An iterative algorithm is suggested to solve the L"q SVM efficiently. Simulations and real data applications support the effectiveness of the proposed procedure.
- Published
- 2007
240. The 𝐿_{𝑞} support vector machine
- Author
-
Yufeng Liu, Hao Helen Zhang, Cheolwoo Park, and Jeongyoun Ahn
- Published
- 2007
241. Variable selection for proportional odds model
- Author
-
Wenbin Lu and Hao Helen Zhang
- Subjects
Statistics and Probability ,Likelihood Functions ,Mathematical optimization ,Epidemiology ,Proportional hazards model ,Computation ,Process (computing) ,Feature selection ,Survival Analysis ,United States ,Marginal likelihood ,Lasso (statistics) ,Statistics ,Ordered logit ,Algorithms ,Proportional Hazards Models ,Mathematics - Abstract
In this paper we study the problem of variable selection for the proportional odds model, which is a useful alternative to the proportional hazards model and might be appropriate when the proportional hazards assumption is not satisfied. We propose to fit the proportional odds model by maximizing the marginal likelihood subject to a shrinkage-type penalty, which encourages sparse solutions and hence facilitates the process of variable selection. Two types of shrinkage penalties are considered: the LASSO and the adaptive-LASSO (ALASSO) penalty. In the ALASSO penalty, different weights are imposed on different coefficients such that important variables are more protectively retained in the final model while unimportant ones are more likely to be shrunk to zeros. We further provide an efficient computation algorithm to implement the proposed methods, and demonstrate their performance through simulation studies and an application to real data. Numerical results indicate that both methods can produce accurate and interpretable models, and the ALASSO tends to work better than the usual LASSO.
- Published
- 2007
242. Publication in More Than One Language
- Author
-
Yuehong (Helen) Zhang
- Subjects
History ,Publishing ,business.industry ,Journal editor ,Library science ,Duplicate publication ,business ,Variety (linguistics) ,Audience measurement - Abstract
For a variety of reasons, journal articles may be republished in translation (although this cannot be detected by computerized text-matching tools such as CrossCheck). It may be, for example, that the original language of publication is unlikely to reach one part of the author’s intended readership. This raises the difficult question of whether or not this constitutes duplicate publication.
- Published
- 2015
243. Avoiding Plagiarism as an Author
- Author
-
Yuehong (Helen) Zhang
- Subjects
Academic career ,ComputingMilieux_THECOMPUTINGPROFESSION ,Academic skills ,Notice ,Order (business) ,Engineering ethics ,Psychology ,Scientific misconduct ,Paraphrase ,Compliance (psychology) - Abstract
As an author in order to avoid plagiarism, the best way is learning and compliance with the basic principles of good academic from your academic career’s starting. And as signaled by the University of Oxford’s website ‘avoiding plagiarism is not simply a matter of making sure your references are all correct, or changing enough words so the examiner will not notice your paraphrase; it is about deploying your academic skills to make your work as good as it can be’.
- Published
- 2015
244. Dealing with Plagiarism as an Editor
- Author
-
Yuehong (Helen) Zhang
- Subjects
World Wide Web ,Set (abstract data type) ,Academic integrity ,Software ,business.industry ,Computer science ,Journal editor ,Research integrity ,business ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Data science - Abstract
As comments by Nature in 2010, ‘Major science publishers are gearing up to fight plagiarism… including Elsevier and Springer, are set to roll out software across their journals that will scan submitted papers for identical or paraphrased chunks of text that appear in previously published articles [1]’.
- Published
- 2015
245. Concluding Remarks: The Future of Plagiarism
- Author
-
Yuehong (Helen) Zhang
- Subjects
Philosophy ,Research integrity ,Scientific misconduct ,Open access journal ,Epistemology - Abstract
As this book has made clear, plagiarism is an offence against research integrity itself. So, in looking forward, let us consider how the whole culture of research integrity might be improved.
- Published
- 2015
246. Biosciences: Replication of Methods Sections
- Author
-
Yuehong (Helen) Zhang
- Subjects
Engineering ,business.industry ,Journal editor ,Key (cryptography) ,Subject areas ,Engineering ethics ,business ,Discipline ,Biomedicine ,Replication (computing) - Abstract
In our first survey (see Chap. 2), we noticed some significant differences in the responses to some of the questions between the subject areas of Biomedicine and Biotechnology, and Computers and Electronics. We therefore decided to conduct a further investigation focusing on these key differences in approach in these disciplinary fields.
- Published
- 2015
247. What Is Plagiarism?
- Author
-
Yuehong (Helen) Zhang
- Subjects
Academic dishonesty ,Honesty ,media_common.quotation_subject ,Engineering ethics ,Psychology ,Human society ,media_common - Abstract
Plagiarism is a form of academic dishonesty, and the importance of honesty in human society is not a new topic!
- Published
- 2015
248. Differences Between Anglophone and Non-anglophone Journals
- Author
-
Yuehong (Helen) Zhang
- Subjects
Publishing ,business.industry ,Zhàng ,Publication ethics ,Library science ,Sociology ,business - Abstract
As mentioned in the Preface, in 2011 the author and her colleagues received a grant from the Committee on Publication Ethics (COPE) in support of a research study intended to develop evidence-based guidance for journal editors on how to deal with different kinds of plagiarism detected through the use of CrossCheck (COPE Research Grant in CrossCheck guidance: an analysis of typical cases of plagiarism in different disciplines, 2010). The first part of the research was a global survey of journal editors and publishers, the results of which were published in an article entitled ‘A survey on the use of Cross Check in detecting plagiarism in academic journals’, which appeared in Learned Publishing in 2012 (Zhang and Jia in Learned Publishing 25, 2012). The article is reproduced in its entirety (with the publisher’s permission) below.
- Published
- 2015
249. Detecting Potential Plagiarism
- Author
-
Yuehong (Helen) Zhang
- Subjects
World Wide Web ,Computer science ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,Journal editor ,Plagiarism detection ,Knowledge infrastructure ,China ,Variety (linguistics) - Abstract
There are now a variety of online tools available which can compare a submitted text with texts already in its database (or freely available online). The most widely used are CrossCheck, which is mainly used for texts in English, and AMLC (Academic Manuscript Literature Checking) from CNKI (China National Knowledge Infrastructure) that almost covers all contents of Chinese Integrated Knowledge Resources Database and is mainly used for texts in Chinese.
- Published
- 2015
250. Computing and Electrical and Electronic Engineering: Republication of Conference Papers
- Author
-
Yuehong (Helen) Zhang
- Subjects
Computer science ,Electronic engineering ,Permission ,Field (computer science) - Abstract
The republication of conference proceedings as journal articles seems to be particularly prevalent in the areas of Computing and Electrical and Electronic Engineering. Our own use of CrossCheck turned up a disproportionate amount of duplication of this type in these particular disciplines; we also noted in our previous survey (see Chap. 2) that the attitudes to this question of authors in this area were markedly different from those in other fields. We therefore felt that it would be useful to carry out a survey of the attitudes of the editors of relevant journals to this issue; we surveyed over 300 journals in the field, and the results were published in an article entitled ‘Republication of conference papers in journals?’, which is reproduced in full (with the publisher’s permission) below [1].
- Published
- 2015
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