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Principal axes of M-DOF structures Part I:Static loading

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Earthquake Engineering and Engineering Vibration 2002年第2期1卷 293-302页

作者： zack Liang George C.Lee Department of Civil Structural and Environmental EngineeringUniversity.at BuffaloState University.of New YorkBuffaloNew YorkUSA Multidisciplinary Center for Earthquake Engineering Research University at BuffaloState University of New YorkBuffaloNew YorkUSA

This paper is the first in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads. The primary purpose of this series is to understand the magnitude of the dynamic response of structures to enable better design of structures and control modification devices/systems. Under idealized design conditions, the structural responses are obtained by using single direction input ground motions in the direction of the intended control devices/systems, and by assuming that the responses of the structure is decoupleable in three mutually perpendicular directions. This standard practice has been applied to both new and retrofitted structures using various seismic protective systems. Very limited information is available on the effects of neglecting the impact of directional couplings (cross effects - of which torsion is a component) of the dynamic response of structures. In order to quantify such effects, it is necessary to examine the principal axes of structures under both static and dynamic loading. This first paper deals with quantitative definitions of principal axes and “cross effects” of three-dimensional structures under static load by using linear algebra. It shows theoretically that, for three-dimensional structures, such principal axes rarely exist. Under static loading conditions, the cross effect is typically small and negligible from the viewpoint of engineering applications. However, it provides the theoretical base for subsequent quantification of the response couplings under dynamic loads, which is reported in part II of this series.

关键词： principal axes of M-DOF structures structural response couplings cross effect theoretical base

Characterization of Binding Sites of Eukaryotic Transcription Factors

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Genomics, Proteomics & Bioinformatics 2006年第2期4卷 67-79页

作者： Jiang Qian Jimmy Lin Donald J. zack The Wilmer Institute Department of Molecular Biology and Genetics Department of Neuroscience McKusick-Nathans Institute of Genetic Medicine Johns Hopkins University School of Medicine Baltimore MD 21287 USA.

To explore the nature of eukaryotic transcription factor （TF） binding sites and determine how they differ from surrounding DNA sequences, we examined four features associated with DNA binding sites： G＋C content, pattern complexity, palindromic structure, and Markov sequence ordering. Our analysis of the regulatory motifs obtained from the TRANSFAC databases using yeast intergenic sequences as background, revealed that these four features show variable enrichment in motif sequences. For example, motif sequences were more likely to have palindromic structure than were background sequences. In addition, these features were tightly localized to the regulatory motifs, indicating that they are a property of the motif sequences themselves and are not shared by the general promoter ＂environment＂ in which the regulatory motifs reside. By breaking down the motif sequences according to the TF classes to which they bind, more specific associations were identified. Finally, we found that some correlations, such as G＋C content enrichment, were species-specific, while others, such as complexity enrichment, were universal across the species examined. The quantitative analysis provided here should increase our understanding of protein-DNA interactions and also help facilitate the discovery of regulatory motifs through bioinformatics.

关键词： transcription factor promoter gene regulation bioinformatics

Single-layer graphene as a highly selective barrier for vanadium crossover with high proton selectivity

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Journal of Energy Chemistry 2021年第8期30卷 419-430,I0009页

作者： Saheed Bukola Zhaodong Li Jason zack Christopher Antunes Carol Korzeniewski Glenn Teeter Jeffrey Blackburn Bryan Pivovar National Renewable Energy Laboratory(NREL) 80401 GoldenUnited States Department of Chemistry Texas Tech University79409 LubbockUnited States*Corresponding author(email:Saheed.Bukola@nrel.gov

We report near-zero crossover for vanadium cross-permeation through single-layer graphene immobilized at the interface of two Nafion?polymer electrolyte *** ion diffusion and migration,including proton mobility through membrane composites,were studied with and without graphene under diffusion and migration ***-layer graphene was found to effectively inhibit vanadium ion diffusion and migration under specific *** single-layer graphene composites also enabled remarkable ion transmission selectivity improvements over pure Nafion membranes,with proton transport being four orders of magnitude faster than vanadium ion *** values of 0.02±0.005Ωcm^(2) for proton and 223±4Ωcm^(2) for vanadium ion through single atomic layer graphene are *** high selectivity may have significant impact on flow battery applications or for other electrochemical devices where proton conductivity is required,and transport of other species is *** results emphasize that crossover may be essentially completely eliminated in some cases,enabling for greatly improved operational viability.

关键词： Ion selectivity Polymer electrolyte membrane Redox flow battery Single-layer graphene Vanadium crossover 2D nanomaterial

Current progress in use of adipose derived stem cells in peripheral nerve regeneration

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World Journal of Stem Cells 2015年第1期7卷 51-64页

作者： Shomari DL zack-Williams Peter E Butler Deepak M Kalaskar Centre for Nanotechnology and Regenerative Medicine Division of Surgery and Interventional Science University College London WC1E 6BT London United Kingdom Department of Plastic and Reconstructive Surgery Royal Free Hampstead NHS Trust Hospital NW3 2QG London United Kingdom

Unlike central nervous system neurons; those in the peripheral nervous system have the potential for full regeneration after injury. Following injury, recovery is controlled by schwann cells which replicate and modulate the subsequent immune response. The level of nerve recovery is strongly linked to the severity of the initial injury despite the significant advancements in imaging and surgical techniques. Multiple experimental model shave been used with varying successes to augment the natural regenerative processes which occur following nerve injury. Stem cell therapy in peripheral nerve injury may be an important future intervention to improve the best attainable clinical results. In particular adipose derived stem cells(ADSCs) are multipotent mesenchymal stem cells similar to bone marrow derived stem cells, which are thought to have neurotrophic properties and the ability to differentiate into multiple lineages. They are ubiquitous within adipose tissue; they can form many structures resembling the mature adult peripheral nervous system. Following early in vitro work; multiple small and large animal in vivo models have been used in conjunction with conduits, autografts and allografts to successfully bridge the peripheral nerve gap. Some of the ADSC related neuroprotective and regenerative properties have been elucidated however much work remains before a model can be used successfully in human peripheral nerve injury(PNI). This review aims to provide a detailed overview of progress made in the use of ADSC in PNI, with discussion on the role of a tissue engineered approach for PNI repair.

关键词： Peripheral nerve injury Adipose derivedstem cells Cell based therapies Stem cells

Adaptive Thermoforming and Structural Design of Millimeter-Wave Antenna Panels

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Nanomanufacturing and Metrology 2022年第4期5卷 327-335页

作者： zack Hatfield Alex St.Peter Christian Davila-Peralta Joel Berkson Daewook Kim Justin Hyatt James C.Wyant College of Optical Sciences University of Arizona1630 E.University BlvdTucsonAZ85721USA Department of Astronomy and Steward Observatory University of Arizona933 N.Cherry AveTucsonAZ85721USA

Future large-scale radio telescope observatories,such as the next-generation Very Large Array,involve extremely large collection *** collection areas are divided into smaller shaped panels,which typically require their own unique molds to *** these projects to be cost-effective,an efficient fabrication method for the shaped panels is *** paper outlines the development and success of a novel adaptive freeform panel molding technology that greatly improves manufacturing efficiency due to its repeatable and reusable ***,it presents an analysis of a proposed panel structural design for the shaped panels,which incorporates a study on surface deformation due to gravity and wind loading under realistic operational conditions.

关键词： Radio telescope Millimeter-wave Thermoform Adaptable mold

Late Cenozoic sedimentary process and its response to the slip history of the central Altyn Tagh fault,NW China

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Science China Earth Sciences 2001年第S1期44卷 103-111页

作者：陈正乐张岳桥陈宣华王小凤 A.S.Ramon W.B.zack Chinese Acad Geol Sci Inst Geomech Beijing 100081 Peoples R China Arizona State Univ Dept Geol Tempe AZ 85287 USA

The ENE-striking Altyn Tagh fault (ATF), extending along the northern edge of the Tibetan Plateau, is one of the major important strike-slip faults, and has been known as one of the key areas to debate the eastward extrusion and crustral shortening models of the Tibetan Plateau during and after India-Asia collision. This paper mainly presents new evidence of Late Cenozoic sedimentary process to reconstruct the slip history of the ATF during the Late Cenozoic. Field measurements and laboratory analyses of the sedimentary characteristics in the Late Cenozoic basins in the central Altyn Tagh fault suggest that Late Cenozoic sedimentary sequence should be divided into three units according to facies changes. The paleo-topography reconstruction shows that the sedimentation in these basins was tightly related with the fault, indicating that the ATF has experienced at least three stages of strike slipping in the Late Cenozoic. New geological data from the Late Cenozoic sedimentary basins and the formation of the present Suo'erkuli basin provide evidence for the displacement of the fault. The result shows that the 80-100 km left-lateral strike-slip displacement of the fault has been accumulated in the Late Cenozoic.

关键词： Altyn Tagh fault Late Cenozoic slip history sedimentary process.

Then and Now： A Content Analysis of Media Used in the Presidential Election Campaigns of Kennedy and Obama

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Sociology Study 2011年第1期1卷 1-10页

作者： zack Stiegler Mary Beth Leidman Indiana University of Pennsylvania Indiana PA USA

American campaigning has become increasingly complex as it adjusts to our ever-changing cultural landscape. The use of electronic media in the presidential campaigns of 1960 and 2008 is illustrative of this shift. A content analysis of these two campaigns demonstrates how each applied the newest technologies available at the time to define the candidate＇s image and export the messages to the electorate. Whether it be Kennedy＇s use of television or Obama＇s usage of social media, the role that new media of the day played in both campaigns clearly set the tone for future political campaigns. This examination of the role of media in both elections serves to form a primer for how the successful applications of new media lead to campaign victory. Then and now, the growing influence of new technologies on campaigning makes it necessary to compare and contrast the successful usages and strategies employed. The need for continuing analysis will grow in the coming years.

关键词： Presidential politics campaigns political communication Barack Ohama John F. Kennedy

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我要成为专业摄影师

作者： (美)zack Arias

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