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Comparison of Cox Model Methods in A Low-dimensional Setting with Few Events

Genomics, Proteomics & Bioinformatics 2016年第4期14卷 235-243页

作者： Francisco M. Ojeda Christian Miiller Daniela Bornigen david-alexandre tregouet Arne Schillert Matthias Heinig Tanja Zeller Renate B. Schnabel Department of General and Interventional Cardiology University Heart Center Hamburg-Eppendorf 20246 Hamburg Germany German Center for Cardiovascular Research (DZHK) Hamburg |Kiel| Luebeck Germany Sorbonne Universites University Pierre et Marie Curie Paris 06 Institut National pour la Sante et la Recherche Medicale (INSERM) Unite Mixte de Recherche en Sante (UMR_S) 1166 F-75013 Paris France Institute for Cardiometaholism and Nutrition (ICAN) F-75013 Paris France Institut fur Medizinische Biometrie und Statistik Universitat zu Lubeck Universitatsklinikum Schleswig-Holstein Campus Lubeck 23562 Lubeck Germany Institute of Computational Biology German Research Center for Environmental Health Helmholtz Zentrum Munchen 85764 Neuherberg Germany

Prognostic models based on survival data frequently make use of the Cox proportional hazards model. Developing reliable Cox models with few events relative to the number of predictors can be challenging, even in low-dimensional datasets, with a much larger number of observations than variables. In such a setting we examined the performance of methods used to estimate a Cox model, including （i） full model using all available predictors and estimated by standard techniques, （ii） backward elimination （BE）, （iii） ridge regression, （iv） least absolute shrinkage and selection operator （lasso）, and （v） elastic net. Based on a prospective cohort of patients with manifest coronary artery disease （CAD）, we performed a simulation study to compare the predictive accuracy, calibration, and discrimination of these approaches, Candidate predictors for incident cardiovascular events we used included clinical variables, biomarkers, and a selection of genetic variants associated with CAD. The penalized methods, i.e., ridge, lasso, and elastic net, showed a comparable performance, in terms of predictive accuracy, calibration, and discrimination, and outperformed BE and the full model. Excessive shrinkage was observed in some cases for the penalized methods, mostly on the simulation scenarios having the lowest ratio of a number of events to the number of variables. We conclude that in similar settings, these three penalized methods can be used interchangeably. The full model and backward elimination are not recommended in rare event scenarios.

关键词： Proportional hazards regression Penalized regression Events per variable Coronary artery disease

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Making bridges between preclinical and clinical insights into age-related cognitive decline

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Neural Regeneration Research 2025年第8期20卷 2321-2322页

作者： david VC Brito Clévio Nóbrega Algarve Biomedical Center-Research Institute(ABC-RI) Campus GambelasFaroPortugal Algarve Biomedical Center-(ABC) Campus GambelasFaroPortugal Faculty of Medicine and Biomedical Sciences(FMCB) University of AlgarveGambelas CampusFaroPortugal

With people living longer,the societal impact of age-related cognitive decline is becoming more pronounced(Crimmins,2015).Thus,it is increasingly important to comprehend the cognitive shifts linked to aging-whether th... 详细信息

关键词： bridges becoming insight

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Women in visual neural regeneration research

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Neural Regeneration Research 2025年第2期20卷 489-490页

作者： Tonia S.Rex david J.Calkins Vanderbilt Eye Institute Vanderbilt University Medical CenterNashvilleTNUSA

The year 2024 marks the 60^(th)anniversary of Title IX and 25 years since the New York Times revealed bias against female faculty members at the Massachusetts Institute of *** take an opportunity here to examine the state of gender bias in a relatively new yet already prominent field,neural regeneration in the visual system,for which there is a well-defined context useful for this *** National Eye Institute(NEI)provided the first round of research funding for its Audacious Goals Initiative(AGI)on visual neural regeneration in 2013 and the last round in ***,we focus on this *** sources included PubMed,the National Science Foundation(NSF),the NEI,the Blue Ridge Institute for Medical Research and data from the major professional organization for eye and vision research,the Association for Research in Vision and Ophthalmology(ARVO).

关键词： neural visual Times

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The geography of introgression in a patchy environment and the thorn in the side of ecological speciation

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Current Zoology 2013年第1期59卷 72-86页

作者： Nicolas BIERNE Pierre-alexandre GAGNAIRE Patrice david Universit6 Montpellier 2 Place Eugene Bataillon 34095 Montpellier Cedex 5 France ISEM - CNRS UMR 5554 SMEL 2 rue des Chantiers 34200 S6te France CEFE - CNRS UMR 5175 34293 MontpeUier Cedex 5 France

When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic structure of selected traits/loci tends to coincide with habitat variables （producing Genetic-Environment Association or GEA）, genetic differentiation at neutral loci unlinked to any selected locus rather depends on geographic connectivity at a large scale （e.g. Isolation- By-Distance or IBD）, although these loci often display GEA at a small scale. This discrepancy has been repeatedly taken as evi- dence for parallel primary divergence driven by local adaptation. We argue that this interpretation needs to be addressed more thoroughly by considering the alternative hypothesis that speciation was initiated in allopatry and secondary introgression has subsequently erased the signal of past differentiation at neutral loci. We present a model of neutral introgression after secondary contact in a mosaic hybrid zone, which describes how GEAs dissipate with time and how neutral variation self-organizes accord- ing to the environmental and geographic structures. We show that although neutral loci can be affected by environmental selection they are often more affected by history and connectivity： the neutral structure retains the initial geographic separation more than it correlates with the environment during the colonization and introgression phases, and then converges to a migration-drift balance, the most frequent outcome of which is GEA at a local scale but IBD at a large scale. This is the exact pattern usually attributed to parallel ecological speciation. Introgression is heterogeneous in space and depends on the landscape structure （e.g. it is faster in small patches, which are more impacted by immigration）. Furthermore, there is no directionality in the association and it is possi- ble to observe reversed GEAs between distant regions. We argue that the his

关键词： Ecological speciation Local adaptation Mosaic hybrid zone Reproductive isolation Genetic-environment association

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A new modeling approach of pressure waves at the inlet of internal combustion engines

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Journal of Thermal Science 2011年第2期20卷 181-188页

作者： david Chalet alexandre Mahé Jean-Franois Hétet Jérme Migaud Internal Combustion Engine Team Laboratory of Fluid Mechanics UMR CNRS 6598 Ecole Centrale de Nantes Advanced development Mann+Hummel France

This paper presents a new model used to describe the propagation of pressure waves at the inlet systems of internal combustion engine. In the first part, an analogy is made between the compressible air in a pipe and a mechanical ideal mass damper spring system. A new model is then presented and the parameters of this model are determined by the use of an experimental setup (shock tube test bench). With this model, a transfer function is defined in order to link directly the pressure and the air mass flow rate. In the second part, the model is included into an internal combustion engine simulation code. The results obtained with this code are compared to experimental ones which are measured on a one-cylinder engine test bench. This last one is driven by an electric motor in order to study only the effect of the pressure waves on the engine behavior. A good agreement is obtained between the experimental results and the numerical ones and the new approach is an alternative method for modeling the pressure wave phenomena in an internal combustion engine manifold.

关键词： gas dynamics pressure wave compressible flow frequency analysis transfer function internal combustion engine

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Gate length dependent transport properties of in-plane core-shell nanowires with raised contacts

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Nano Research 2020年第1期13卷 61-66页

作者： alexandre Bucamp Christophe Coinon david Troadec Sylvie Lepilliet Gilles Patriarche Xavier Wallart Ludovic Desplanque Univ.Lille CNRSCentrale LilleYncréa ISENUniv.Polytechnique Hauts-de-FranceUMR 8520-IEMNF-59000LilleFrance C2N-UMR 9001 CNRS UniversitéParis-Sud-UniversitéParis-Saclay91120PalaiseauFrance

Three-dimensional(3D)nanoscale crystal shaping has become essential for the precise design of advanced electronic and quantum devices based on electrically gated *** this context,Ⅲ-Ⅴ semiconductor-based nanowires with low electron effective mass and strong spin-orbit coupling are particularly investigated because of their exceptional quantum transport properties and the good electrostatic control they *** the main challenges involved in the processing of these nanodevices are(i)the management of the gate stack which requires ex-situ passivation treatment to reduce the density of traps at the oxide/semiconductor interface,(ii)the ability to get good ohmic contacts for source and drain electrodes and(iii)the scalability and reliability of the process for the fabrication of complex architectures based on nanowire *** this paper,we show that selective area molecular beam epitaxy of in-plane InGaAs/InP core-shell nanowires with raised heavily doped source and drain contacts can address these different *** characterization of the devices down to 4 K reveals the positive impact of the InP shell on the gate electrostatic control and effective electron *** comparable to the best reported values for In(Ga)As nanostructures grown on InP,this latter is severely reduced for sub-100 nm channel highlighting remaining issue to reach the ballistic regime.

关键词： molecular beam epitaxy core-shell nanowire selective area growth effective electron mobility

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An evaluation framework for energy aware buildings using statistical model checking

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Science China(Information Sciences) 2012年第12期55卷 2694-2707页

作者： david alexandre LARSEN Kim G. MIKUIONIS Marius SKOU Arne Center for Embedded Software Systems Department of Computer ScienceAalborg University

Cyber-physical systems are to be found in numerous applications throughout *** principal barrier to develop trustworthy cyber-physical systems is the lack of expressive modelling and specification formalisms supported by efficient tools and *** overcome this barrier,we extend in this paper the modelling formalism of the tool UPPAAL-SMC to stochastic hybrid automata,thus providing the expressive power required for modelling complex cyber-physical *** application of Statistical Model Checking provides a highly scalable technique for analyzing performance properties of this formalisms.A particular kind of cyber-physical systems are Smart Grids which together with Intelligent,Energy Aware Buildings will play a major role in achieving an energy efficient society of the *** this paper we present a framework in UPPAAL-SMC for energy aware buildings allowing to evaluate the performance of proposed control strategies in terms of their induced comfort and energy profiles under varying environmental settings(***,user behavior etc.).To demonstrate the intended use and usefulness of our framework,we present an application to the Hybrid Systems Verification Benchmark.

关键词： timed automata stochastic hybrid systems model checking statistical model checking performance evaluation energy consumption cyber physical systems smart grid energy aware buildings

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Research and development of VUV optical coatings for micro mirror applications

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光学精密工程 2005年第4期13卷 465-470页

作者： alexandre Gatto Norbert Kaiser Fraunhofer IOF Albert-Einstein-Str. 7 D-07745 Jena GermanyFraunhofer IOF Albert-Einstein-Str. 7 D-07745 Jena Germany

This paper deals with vacuum UV optical coatings for micro mirror applications. High reflecting low-stress optical coatings have been developed for the next-generation of micro mechanical mirrors. The optimized metal systems are applicable in the VUV spectral region and can be integrated in the technology of MOEMS, such as spatial light modulators (SLM) and micro scanning mirrors.

关键词： VUV 光学涂覆技术微镜技术薄膜调节器

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Towards a modular and scalable holographic display

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Light(Science & Applications) 2022年第5期11卷 739-740页

作者： Pierre-alexandre Blanche Wyant College of Optical Sciences University of ArizonaTucsonAZUSA

Holographic three-dimensional(3D)display can be made very large using a modular system that allows seamless spatial tiling of multiple coarse integral holographic images.

关键词： holographic system integral

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Colon mucus in colorectal neoplasia and beyond

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World Journal of Gastroenterology 2022年第32期28卷 4475-4492页

作者： alexandre Loktionov DiagNodus Ltd Cambridge CB40WSUnited Kingdom

Little was known about mammalian colon mucus(CM)until the beginning of the 21^(st) *** that time considerable progress has been made in basic research addressing CM structure and *** CM is formed by two distinct layers composed of gel-forming glycosylated mucins that are permanently secreted by goblet cells of the colonic *** inner layer is dense and impenetrable for bacteria,whereas the loose outer layer provides a habitat for abundant commensal *** barrier integrity is essential for preventing bacterial contact with the mucosal epithelium and maintaining homeostasis in the gut,but it can be impaired by a variety of factors,including CM-damaging switch of commensal bacteria to mucin glycan consumption due to dietary fiber *** is proven that impairments in CM structure and function can lead to colonic barrier deterioration that opens direct bacterial access to the ***-induced damage dysregulates epithelial proliferation and causes mucosal inflammatory responses that may expand to the loosened CM and eventually result in severe disorders,including colitis and neoplastic *** described formation of bacterial biofilms within the inner CM layer was shown to be associated with both inflammation and *** obvious gaps in our knowledge of human CM remain,its importance for the pathogenesis of major colorectal diseases,comprising inflammatory bowel disease and colorectal cancer,is already *** progress in CM exploration is likely to result in the development of a range of new useful clinical applications addressing colorectal disease diagnosis,prevention and therapy.

关键词： Colon Colon mucus Mucins Goblet cells Gut microbiota Inflammatory bowel disease Colorectal cancer

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