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Sample records for challenge reverse engineer

  1. Reverse engineering biomolecular systems using -omic data: challenges, progress and opportunities.

    PubMed

    Quo, Chang F; Kaddi, Chanchala; Phan, John H; Zollanvari, Amin; Xu, Mingqing; Wang, May D; Alterovitz, Gil

    2012-07-01

    Recent advances in high-throughput biotechnologies have led to the rapid growing research interest in reverse engineering of biomolecular systems (REBMS). 'Data-driven' approaches, i.e. data mining, can be used to extract patterns from large volumes of biochemical data at molecular-level resolution while 'design-driven' approaches, i.e. systems modeling, can be used to simulate emergent system properties. Consequently, both data- and design-driven approaches applied to -omic data may lead to novel insights in reverse engineering biological systems that could not be expected before using low-throughput platforms. However, there exist several challenges in this fast growing field of reverse engineering biomolecular systems: (i) to integrate heterogeneous biochemical data for data mining, (ii) to combine top-down and bottom-up approaches for systems modeling and (iii) to validate system models experimentally. In addition to reviewing progress made by the community and opportunities encountered in addressing these challenges, we explore the emerging field of synthetic biology, which is an exciting approach to validate and analyze theoretical system models directly through experimental synthesis, i.e. analysis-by-synthesis. The ultimate goal is to address the present and future challenges in reverse engineering biomolecular systems (REBMS) using integrated workflow of data mining, systems modeling and synthetic biology.

  2. Reverse engineering biomolecular systems using −omic data: challenges, progress and opportunities

    PubMed Central

    Quo, Chang F.; Kaddi, Chanchala; Phan, John H.; Zollanvari, Amin; Xu, Mingqing

    2012-01-01

    Recent advances in high-throughput biotechnologies have led to the rapid growing research interest in reverse engineering of biomolecular systems (REBMS). ‘Data-driven’ approaches, i.e. data mining, can be used to extract patterns from large volumes of biochemical data at molecular-level resolution while ‘design-driven’ approaches, i.e. systems modeling, can be used to simulate emergent system properties. Consequently, both data- and design-driven approaches applied to –omic data may lead to novel insights in reverse engineering biological systems that could not be expected before using low-throughput platforms. However, there exist several challenges in this fast growing field of reverse engineering biomolecular systems: (i) to integrate heterogeneous biochemical data for data mining, (ii) to combine top–down and bottom–up approaches for systems modeling and (iii) to validate system models experimentally. In addition to reviewing progress made by the community and opportunities encountered in addressing these challenges, we explore the emerging field of synthetic biology, which is an exciting approach to validate and analyze theoretical system models directly through experimental synthesis, i.e. analysis-by-synthesis. The ultimate goal is to address the present and future challenges in reverse engineering biomolecular systems (REBMS) using integrated workflow of data mining, systems modeling and synthetic biology. PMID:22833495

  3. Engineering Encounters: Reverse Engineering

    ERIC Educational Resources Information Center

    McGowan, Veronica Cassone; Ventura, Marcia; Bell, Philip

    2017-01-01

    This column presents ideas and techniques to enhance your science teaching. This month's issue shares information on how students' everyday experiences can support science learning through engineering design. In this article, the authors outline a reverse-engineering model of instruction and describe one example of how it looked in our fifth-grade…

  4. Reverse engineering and identification in systems biology: strategies, perspectives and challenges.

    PubMed

    Villaverde, Alejandro F; Banga, Julio R

    2014-02-06

    The interplay of mathematical modelling with experiments is one of the central elements in systems biology. The aim of reverse engineering is to infer, analyse and understand, through this interplay, the functional and regulatory mechanisms of biological systems. Reverse engineering is not exclusive of systems biology and has been studied in different areas, such as inverse problem theory, machine learning, nonlinear physics, (bio)chemical kinetics, control theory and optimization, among others. However, it seems that many of these areas have been relatively closed to outsiders. In this contribution, we aim to compare and highlight the different perspectives and contributions from these fields, with emphasis on two key questions: (i) why are reverse engineering problems so hard to solve, and (ii) what methods are available for the particular problems arising from systems biology?

  5. Reverse engineering and identification in systems biology: strategies, perspectives and challenges

    PubMed Central

    Villaverde, Alejandro F.; Banga, Julio R.

    2014-01-01

    The interplay of mathematical modelling with experiments is one of the central elements in systems biology. The aim of reverse engineering is to infer, analyse and understand, through this interplay, the functional and regulatory mechanisms of biological systems. Reverse engineering is not exclusive of systems biology and has been studied in different areas, such as inverse problem theory, machine learning, nonlinear physics, (bio)chemical kinetics, control theory and optimization, among others. However, it seems that many of these areas have been relatively closed to outsiders. In this contribution, we aim to compare and highlight the different perspectives and contributions from these fields, with emphasis on two key questions: (i) why are reverse engineering problems so hard to solve, and (ii) what methods are available for the particular problems arising from systems biology? PMID:24307566

  6. Reverse Engineering Molecular Hypergraphs

    PubMed Central

    Rahman, Ahsanur; Poirel, Christopher L.; Badger, David J.; Estep, Craig; Murali, T.M.

    2014-01-01

    Analysis of molecular interaction networks is pervasive in systems biology. This research relies almost entirely on graphs for modeling interactions. However, edges in graphs cannot represent multiway interactions among molecules, which occur very often within cells. Hypergraphs may be better representations for networks having such interactions, since hyperedges can naturally represent relationships among multiple molecules. Here, we propose using hypergraphs to capture the uncertainty inherent in reverse engineering gene-gene networks. Some subsets of nodes may induce highly varying subgraphs across an ensemble of networks inferred by a reverse engineering algorithm. We provide a novel formulation of hyperedges to capture this uncertainty in network topology. We propose a clustering-based approach to discover hyperedges. We show that our approach can recover hyperedges planted in synthetic data sets with high precision and recall, even for moderate amount of noise. We apply our techniques to a data set of pathways inferred from genetic interaction data in S. cerevisiae related to the unfolded protein response. Our approach discovers several hyperedges that capture the uncertain connectivity of genes in relevant protein complexes, suggesting that further experiments may be required to precisely discern their interaction patterns. We also show that these complexes are not discovered by an algorithm that computes frequent and dense subgraphs. PMID:24384702

  7. Reverse engineering molecular hypergraphs.

    PubMed

    Rahman, Ahsanur; Poirel, Christopher L; Badger, David J; Estep, Craig; Murali, T M

    2013-01-01

    Analysis of molecular interaction networks is pervasive in systems biology. This research relies almost entirely on graphs for modeling interactions. However, edges in graphs cannot represent multiway interactions among molecules, which occur very often within cells. Hypergraphs may be better representations for networks having such interactions, since hyperedges can naturally represent relationships among multiple molecules. Here, we propose using hypergraphs to capture the uncertainty inherent in reverse engineering gene-gene networks. Some subsets of nodes may induce highly varying subgraphs across an ensemble of networks inferred by a reverse engineering algorithm. We provide a novel formulation of hyperedges to capture this uncertainty in network topology. We propose a clustering-based approach to discover hyperedges. We show that our approach can recover hyperedges planted in synthetic data sets with high precision and recall, even for moderate amount of noise. We apply our techniques to a data set of pathways inferred from genetic interaction data in S. cerevisiae related to the unfolded protein response. Our approach discovers several hyperedges that capture the uncertain connectivity of genes in relevant protein complexes, suggesting that further experiments may be required to precisely discern their interaction patterns. We also show that these complexes are not discovered by an algorithm that computes frequent and dense subgraphs.

  8. Reverse Core Engine with Thrust Reverser

    NASA Technical Reports Server (NTRS)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)

    2017-01-01

    An engine system has a gas generator, a bi-fi wall surrounding at least a portion of the gas generator, a casing surrounding a fan, and the casing having first and second thrust reverser doors which in a deployed position abut each other and the bi-fi wall.

  9. Reverse engineering quantum field theory

    NASA Astrophysics Data System (ADS)

    Oeckl, Robert

    2012-12-01

    An approach to the foundations of quantum theory is advertised that proceeds by "reverse engineering" quantum field theory. As a concrete instance of this approach, the general boundary formulation of quantum theory is outlined.

  10. Can biological complexity be reverse engineered?

    PubMed

    Green, Sara

    2015-10-01

    Concerns with the use of engineering approaches in biology have recently been raised. I examine two related challenges to biological research that I call the synchronic and diachronic underdetermination problem. The former refers to challenges associated with the inference of design principles underlying system capacities when the synchronic relations between lower-level processes and higher-level systems capacities are degenerate (many-to-many). The diachronic underdetermination problem regards the problem of reverse engineering a system where the non-linear relations between system capacities and lower-level mechanisms are changing over time. Braun and Marom argue that recent insights to biological complexity leave the aim of reverse engineering hopeless - in principle as well as in practice. While I support their call for systemic approaches to capture the dynamic nature of living systems, I take issue with the conflation of reverse engineering with naïve reductionism. I clarify how the notion of design principles can be more broadly conceived and argue that reverse engineering is compatible with a dynamic view of organisms. It may even help to facilitate an integrated account that bridges the gap between mechanistic and systems approaches.

  11. Reverse engineering of biochar.

    PubMed

    Morales, Verónica L; Pérez-Reche, Francisco J; Hapca, Simona M; Hanley, Kelly L; Lehmann, Johannes; Zhang, Wei

    2015-05-01

    This study underpins quantitative relationships that account for the combined effects that starting biomass and peak pyrolysis temperature have on physico-chemical properties of biochar. Meta-data was assembled from published data of diverse biochar samples (n=102) to (i) obtain networks of intercorrelated properties and (ii) derive models that predict biochar properties. Assembled correlation networks provide a qualitative overview of the combinations of biochar properties likely to occur in a sample. Generalized Linear Models are constructed to account for situations of varying complexity, including: dependence of biochar properties on single or multiple predictor variables, where dependence on multiple variables can have additive and/or interactive effects; non-linear relation between the response and predictors; and non-Gaussian data distributions. The web-tool Biochar Engineering implements the derived models to maximize their utility and distribution. Provided examples illustrate the practical use of the networks, models and web-tool to engineer biochars with prescribed properties desirable for hypothetical scenarios. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Reverse engineering adverse outcome pathways.

    PubMed

    Perkins, Edward J; Chipman, J Kevin; Edwards, Stephen; Habib, Tanwir; Falciani, Francesco; Taylor, Ronald; Van Aggelen, Graham; Vulpe, Chris; Antczak, Philipp; Loguinov, Alexandre

    2011-01-01

    The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. The application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, metabolic, signaling) can be used to overcome these limitations. This approach was used to characterize adverse outcome pathways (AOPs) for chemicals that disrupt the hypothalamus-pituitary-gonadal endocrine axis in fathead minnows (FHM, Pimephales promelas). Gene expression changes in FHM ovaries in response to seven different chemicals, over different times, doses, and in vivo versus in vitro conditions, were captured in a large data set of 868 arrays. Potential AOPs of the antiandrogen flutamide were examined using two mutual information-based methods to infer gene regulatory networks and potential AOPs. Representative networks from these studies were used to predict network paths from stressor to adverse outcome as candidate AOPs. The relationship of individual chemicals to an adverse outcome can be determined by following perturbations through the network in response to chemical treatment, thus leading to the nodes associated with the adverse outcome. Identification of candidate pathways allows for formation of testable hypotheses about key biological processes, biomarkers, or alternative endpoints that can be used to monitor an AOP. Finally, the unique challenges facing the application of this approach in ecotoxicology were identified and a road map for the utilization of these tools presented.

  13. Reverse Engineering Adverse Outcome Pathways

    SciTech Connect

    Perkins, Edward; Chipman, J.K.; Edwards, Stephen; Habib, Tanwir; Falciani, Francesco; Taylor, Ronald C.; Van Aggelen, Graham; Vulpe, Chris; Antczak, Philipp; Loguinov, Alexandre

    2011-01-30

    The toxicological effects of many stressors are mediated through unknown, or poorly characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, metabolic, signaling) to characterize adverse outcome pathways (AOPs) for chemicals that disrupt the hypothalamus-pituitary-gonadal endocrine axis in fathead minnows. Gene expression changes in fathead minnow ovaries in response to 7 different chemicals, over different times, doses, and in vivo versus in vitro conditions were captured in a large data set of 868 arrays. We examined potential AOPs of the antiandrogen flutamide using two mutual information theory methods, ARACNE and CLR to infer gene regulatory networks and potential adverse outcome pathways. Representative networks from these studies were used to predict a network path from stressor to adverse outcome as a candidate AOP. The relationship of individual chemicals to an adverse outcome can be determined by following perturbations through the network in response to chemical treatment leading to the nodes associated with the adverse outcome. Identification of candidate pathways allows for formation of testable hypotheses about key biologic processes, biomarkers or alternative endpoints, which could be used to monitor an adverse outcome pathway. Finally, we identify the unique challenges facing the application of this approach in ecotoxicology, and attempt to provide a road map for the utilization of these tools. Key Words: mechanism of action, toxicology, microarray, network inference

  14. Challenges in cardiac tissue engineering.

    PubMed

    Vunjak-Novakovic, Gordana; Tandon, Nina; Godier, Amandine; Maidhof, Robert; Marsano, Anna; Martens, Timothy P; Radisic, Milica

    2010-04-01

    Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell-the actual "tissue engineer"-is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure.

  15. Reverse engineering of integrated circuits

    DOEpatents

    Chisholm, Gregory H.; Eckmann, Steven T.; Lain, Christopher M.; Veroff, Robert L.

    2003-01-01

    Software and a method therein to analyze circuits. The software comprises several tools, each of which perform particular functions in the Reverse Engineering process. The analyst, through a standard interface, directs each tool to the portion of the task to which it is most well suited, rendering previously intractable problems solvable. The tools are generally used iteratively to produce a successively more abstract picture of a circuit, about which incomplete a priori knowledge exists.

  16. Challenges in Cardiac Tissue Engineering

    PubMed Central

    Tandon, Nina; Godier, Amandine; Maidhof, Robert; Marsano, Anna; Martens, Timothy P.; Radisic, Milica

    2010-01-01

    Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell—the actual “tissue engineer”—is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure. PMID:19698068

  17. Szilard engine reversibility as quantum gate function

    NASA Astrophysics Data System (ADS)

    Mihelic, F. Matthew

    2012-06-01

    A quantum gate is a logically and thermodynamically reversible situation that effects a unitary transformation of qubits of superimposed information, and essentially constitutes a situation for a reversible quantum decision. A quantum decision is a symmetry break, and the effect of the function of a Szilard engine is a symmetry break. A quantum gate is a situation in which a reversible quantum decision can be made, and so if a logically and thermodynamically reversible Szilard engine can be theoretically constructed then it would function as a quantum gate. While the traditionally theorized Szilard engine is not thermodynamically reversible, if one of the bounding walls of a Szilard engine were to be constructed out of the physical information by which it functions in such a manner as to make that information available to both sides of the wall simultaneously, then such a Szilard engine would be both logically and thermodynamically reversible, and thus capable of function as a quantum gate. A theoretical model of the special case of a reversible Szilard engine functioning as a quantum gate is presented and discussed, and since a quantum decision is made when the shutter of a Szilard engine closes, the coherence of linked reversible Szilard engines should be considered as a state during which all of the shutters of linked Szilard engines are open simultaneously.

  18. Extending the boundaries of reverse engineering

    NASA Astrophysics Data System (ADS)

    Lawrie, Chris

    2002-04-01

    In today's market place the potential of Reverse Engineering as a time compression tool is commonly lost under its traditional definition. The term Reverse Engineering was coined way back at the advent of CMM machines and 3D CAD systems to describe the process of fitting surfaces to captured point data. Since these early beginnings, downstream hardware scanning and digitising systems have evolved in parallel with an upstream demand, greatly increasing the potential of a point cloud data set within engineering design and manufacturing processes. The paper will discuss the issues surrounding Reverse Engineering at the turn of the millennium.

  19. Hermes: the engineering challenges

    NASA Astrophysics Data System (ADS)

    Brzeski, Jurek; Gers, Luke; Smith, Greg; Staszak, Nicholas

    2012-09-01

    The Australian Astronomical Observatory is building a 4-channel VPH-grating High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the 3.9 meter Anglo-Australian Telescope (AAT). HERMES will provide a nominal spectral resolving power of 28,000 for Galactic Archaeology with an optional high-resolution mode of 45,000 with the use of a slit mask. HERMES is fed by a fibre positioning robot called 2dF at the telescope prime focus. There are a total of 784 science fibres, which interface with the spectrograph via two separate slit body assemblies, each comprising of 392 science fibers. The slit defines the spectral lines of 392 fibres on the detector. The width of the detector determines the spectral bandwidth and the detector height determines the fibre to fibre spacing or cross talk. Tolerances that follow from this are all in the 10 micrometer range. The slit relay optics must contribute negligibly to the overall image quality budget and uniformly illuminate the spectrograph exit pupil. The latter requirement effectively requires that the relay optics provide a telecentric input at the collimator entrance slit. As a result it is critical to align the optical components to extreme precision required by the optical design. This paper discusses the engineering challenges of designing, optimising, tolerancing and manufacturing of very precise mechanical components for housing optics and the design of low cost of jigs and fixtures for alignment and assembly of the optics.

  20. Reverse engineering the euglenoid movement

    PubMed Central

    Arroyo, Marino; Heltai, Luca; Millán, Daniel; DeSimone, Antonio

    2012-01-01

    Euglenids exhibit an unconventional motility strategy amongst unicellular eukaryotes, consisting of large-amplitude highly concerted deformations of the entire body (euglenoid movement or metaboly). A plastic cell envelope called pellicle mediates these deformations. Unlike ciliary or flagellar motility, the biophysics of this mode is not well understood, including its efficiency and molecular machinery. We quantitatively examine video recordings of four euglenids executing such motions with statistical learning methods. This analysis reveals strokes of high uniformity in shape and pace. We then interpret the observations in the light of a theory for the pellicle kinematics, providing a precise understanding of the link between local actuation by pellicle shear and shape control. We systematically understand common observations, such as the helical conformations of the pellicle, and identify previously unnoticed features of metaboly. While two of our euglenids execute their stroke at constant body volume, the other two exhibit deviations of about 20% from their average volume, challenging current models of low Reynolds number locomotion. We find that the active pellicle shear deformations causing shape changes can reach 340%, and estimate the velocity of the molecular motors. Moreover, we find that metaboly accomplishes locomotion at hydrodynamic efficiencies comparable to those of ciliates and flagellates. Our results suggest new quantitative experiments, provide insight into the evolutionary history of euglenids, and suggest that the pellicle may serve as a model for engineered active surfaces with applications in microfluidics. PMID:23047705

  1. Echidna: the engineering challenges

    NASA Astrophysics Data System (ADS)

    Brzeski, Jurek K.; Gillingham, Peter; Correll, David; Dawson, John; Moore, Anna M.; Muller, Rolf; Smedley, Scott; Smith, Greg A.

    2004-09-01

    The Anglo-Australian Observatory's (AAO's) FMOS-Echidna project is for the Fiber Multi-Object Spectroscopy system for the Subaru Telescope. It includes three parts: the 400-fiber positioning system, the focal plane imager (FPI) and the prime focus corrector. The Echidna positioner concept and the role of the AAO in the FMOS project have been described in previous SPIE proceedings. The many components for the system are now being manufactured, after prototype tests have demonstrated that the required performance will be achieved. In this paper, the techniques developed to overcome key mechanical and electronic engineering challenges for the positioner and the FPI are described. The major performance requirement is that all 400 science fiber cores and up to 14 guide fiber bundles are to be re-positioned to an accuracy of 10μm within 10 minutes. With the fast prime focus focal ratio, a close tolerance on the axial position of the fiber tips must also be held so efficiency does not suffer from de-focus. Positioning accuracy is controlled with the help of the FPI, which measures the positions of the fiber tips to an accuracy of a few μm and allows iterative positioning. Maintaining fiber tips sufficiently co-planar requires accurate control in the assembly of the several components that contribute to such errors. Assembly jigs have been developed and proven adequate for this purpose. Attaining high reliability in an assembly with many small components of disparate materials bonded together, including piezo ceramics, carbon fiber reinforced plastic, hardened steel, and electrical circuit boards, has entailed careful selection and application of cements and tightly controlled soldering for electrical connections.

  2. Reverse Engineering Adverse Outcome Pathways in Ecotoxicology

    EPA Science Inventory

    The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, meabolic, signaling) t...

  3. Reverse Engineering Adverse Outcome Pathways in Ecotoxicology

    EPA Science Inventory

    The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, meabolic, signaling) t...

  4. Challenges in tissue engineering

    PubMed Central

    Ikada, Yoshito

    2006-01-01

    Almost 30 years have passed since a term ‘tissue engineering’ was created to represent a new concept that focuses on regeneration of neotissues from cells with the support of biomaterials and growth factors. This interdisciplinary engineering has attracted much attention as a new therapeutic means that may overcome the drawbacks involved in the current artificial organs and organ transplantation that have been also aiming at replacing lost or severely damaged tissues or organs. However, the tissues regenerated by this tissue engineering and widely applied to patients are still very limited, including skin, bone, cartilage, capillary and periodontal tissues. What are the reasons for such slow advances in clinical applications of tissue engineering? This article gives the brief overview on the current tissue engineering, covering the fundamentals and applications. The fundamentals of tissue engineering involve the cell sources, scaffolds for cell expansion and differentiation and carriers for growth factors. Animal and human trials are the major part of the applications. Based on these results, some critical problems to be resolved for the advances of tissue engineering are addressed from the engineering point of view, emphasizing the close collaboration between medical doctors and biomaterials scientists. PMID:16971328

  5. Grand challenges for biological engineering.

    PubMed

    Yoon, Jeong-Yeol; Riley, Mark R

    2009-09-22

    Biological engineering will play a significant role in solving many of the world's problems in medicine, agriculture, and the environment. Recently the U.S. National Academy of Engineering (NAE) released a document "Grand Challenges in Engineering," covering broad realms of human concern from sustainability, health, vulnerability and the joy of living. Biological engineers, having tools and techniques at the interface between living and non-living entities, will play a prominent role in forging a better future. The 2010 Institute of Biological Engineering (IBE) conference in Cambridge, MA, USA will address, in part, the roles of biological engineering in solving the challenges presented by the NAE. This letter presents a brief outline of how biological engineers are working to solve these large scale and integrated problems of our society.

  6. Automated reverse engineering of nonlinear dynamical systems.

    PubMed

    Bongard, Josh; Lipson, Hod

    2007-06-12

    Complex nonlinear dynamics arise in many fields of science and engineering, but uncovering the underlying differential equations directly from observations poses a challenging task. The ability to symbolically model complex networked systems is key to understanding them, an open problem in many disciplines. Here we introduce for the first time a method that can automatically generate symbolic equations for a nonlinear coupled dynamical system directly from time series data. This method is applicable to any system that can be described using sets of ordinary nonlinear differential equations, and assumes that the (possibly noisy) time series of all variables are observable. Previous automated symbolic modeling approaches of coupled physical systems produced linear models or required a nonlinear model to be provided manually. The advance presented here is made possible by allowing the method to model each (possibly coupled) variable separately, intelligently perturbing and destabilizing the system to extract its less observable characteristics, and automatically simplifying the equations during modeling. We demonstrate this method on four simulated and two real systems spanning mechanics, ecology, and systems biology. Unlike numerical models, symbolic models have explanatory value, suggesting that automated "reverse engineering" approaches for model-free symbolic nonlinear system identification may play an increasing role in our ability to understand progressively more complex systems in the future.

  7. Engineering Design Challenge

    ERIC Educational Resources Information Center

    Wheeler, Lindsay B.; Whitworth, Brooke A.; Gonczi, Amanda L.

    2014-01-01

    The number of students majoring in science, technology, engineering, and math (STEM) is declining due in part to a lack of student interest (Fairweather 2008; NRC 2012; PCAST 2010). One reason may be the difference between how science is done in school and how it is done in the field (Osborne, Simon, and Collins 2003). An interdisciplinary…

  8. Engineering Design Challenge

    ERIC Educational Resources Information Center

    Wheeler, Lindsay B.; Whitworth, Brooke A.; Gonczi, Amanda L.

    2014-01-01

    The number of students majoring in science, technology, engineering, and math (STEM) is declining due in part to a lack of student interest (Fairweather 2008; NRC 2012; PCAST 2010). One reason may be the difference between how science is done in school and how it is done in the field (Osborne, Simon, and Collins 2003). An interdisciplinary…

  9. Engineering the LISA Project: Systems Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Evans, Jordan P.

    2006-01-01

    The Laser Interferometer Space Antenna (LISA) is a joint NASA/ESA mission to detect and measure gravitational waves with periods from 1 s to 10000 s. The systems engineering challenges of developing a giant interferometer, 5 million kilometers on a side, an: numerous. Some of the key challenges are presented in this paper. The organizational challenges imposed by sharing the engineering function between three centers (ESA ESTEC, NASA GSFC, and JPL) across nine time zones are addressed. The issues and approaches to allocation of the acceleration noise and measurement sensitivity budget terms across a traditionally decomposed system are discussed. Additionally, using LISA to detect gravitational waves for the first time presents significant data analysis challenges, many of which drive the project system design. The approach to understanding the implications of science data analysis on the system is also addressed.

  10. Engineering the LISA Project: Systems Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Evans, Jordan P.

    2006-01-01

    The Laser Interferometer Space Antenna (LISA) is a joint NASA/ESA mission to detect and measure gravitational waves with periods from 1 s to 10000 s. The systems engineering challenges of developing a giant interferometer, 5 million kilometers on a side, an: numerous. Some of the key challenges are presented in this paper. The organizational challenges imposed by sharing the engineering function between three centers (ESA ESTEC, NASA GSFC, and JPL) across nine time zones are addressed. The issues and approaches to allocation of the acceleration noise and measurement sensitivity budget terms across a traditionally decomposed system are discussed. Additionally, using LISA to detect gravitational waves for the first time presents significant data analysis challenges, many of which drive the project system design. The approach to understanding the implications of science data analysis on the system is also addressed.

  11. On the reliability of reverse engineering results.

    PubMed

    Amotchkina, Tatiana V; Trubetskov, Michael K; Pervak, Vladimir; Romanov, Boris; Tikhonravov, Alexander V

    2012-08-01

    Determination of actual parameters of manufactured optical coatings (reverse engineering of optical coatings) provides feedback to the design-production chain and thus plays an important role in raising the quality of optical coatings production. In this paper, the reliability of reverse engineering results obtained using different types of experimental data is investigated. Considered experimental data include offline normal incidence transmittance data, offline ellipsometric data, and online transmittance monitoring data recorded during depositions of all coating layers. Experimental data are obtained for special test quarter-wave mirrors with intentional errors in some layers. These mirrors were produced by a well-calibrated magnetron-sputtering process. The intentional errors are several times higher than estimated errors of layer thickness monitoring, and the reliability of their detection is used as a measure of reliability of reverse engineering results. It is demonstrated that the most reliable results are provided by online transmittance data.

  12. Analysis of Ten Reverse Engineering Tools

    NASA Astrophysics Data System (ADS)

    Koskinen, Jussi; Lehmonen, Tero

    Reverse engineering tools can be used in satisfying the information needs of software maintainers. Especially in case of maintaining large-scale legacy systems tool support is essential. Reverse engineering tools provide various kinds of capabilities to provide the needed information to the tool user. In this paper we analyze the provided capabilities in terms of four aspects: provided data structures, visualization mechanisms, information request specification mechanisms, and navigation features. We provide a compact analysis of ten representative reverse engineering tools for supporting C, C++ or Java: Eclipse Java Development Tools, Wind River Workbench (for C and C++), Understand (for C++), Imagix 4D, Creole, Javadoc, Javasrc, Source Navigator, Doxygen, and HyperSoft. The results of the study supplement the earlier findings in this important area.

  13. Reverse engineering the lordosis behavior circuit.

    PubMed

    Pfaff, D W; Kow, L-M; Loose, M D; Flanagan-Cato, L M

    2008-08-01

    Reverse engineering takes the facts we know about a device or a process and reasons backwards to infer the principles underlying the structure-function relations. The goal of this review is to apply this approach to a well-studied hormone-controlled behavior, namely the reproductive stance of female rodents, lordosis. We first provide a brief overview on the considerable amount of progress in the analysis of female reproductive behavior. Then, we propose an analysis of the mechanisms of this behavior from a reverse-engineering perspective with the goal of generating novel hypotheses about the properties of the circuitry elements. In particular, the previously proposed neuronal circuit modules, feedback signals, and genomic mechanisms are considered to make predictions in this manner. The lordosis behavior itself appears to proceed ballistically once initiated, but negative and positive hormonal feedback relations are evident in its endocrine controls. Both rapid membrane-initiated and slow genomic hormone effects contribute to the behavior's control. We propose that the value of the reverse-engineering approach is based on its ability to provide testable, mechanistic hypotheses that do not emerge from either traditional evolutionary or simple reductionistic perspectives, and several are proposed in this review. These novel hypotheses may generalize to brain functions beyond female reproductive behavior. In this way, the reverse-engineering perspective can further develop our conceptual frameworks for behavioral and systems neuroscience.

  14. Dynamic Protocol Reverse Engineering: A Grammatical Inference Approach

    DTIC Science & Technology

    2008-03-01

    instruments of tactical cyber power in digital computer networks. We do not discuss the broader topics of computer network exploitation/protection or...reverse engineering to generate effective instruments of tactical cyber power is a challenging problem. Generation of tactical cyber weapons requires...IP network port mirroring and hubbing out are two techniques for trace collection that do not require instrumenting the protocol under investigation

  15. Network Reverse Engineering Approach in Synthetic Biology

    NASA Astrophysics Data System (ADS)

    Zhang, Haoqian; Liu, Ao; Lu, Yuheng; Sheng, Ying; Wu, Qianzhu; Yin, Zhenzhen; Chen, Yiwei; Liu, Zairan; Pan, Heng; Ouyang, Qi

    2013-12-01

    Synthetic biology is a new branch of interdisciplinary science that has been developed in recent years. The main purpose of synthetic biology is to apply successful principles that have been developed in electronic and chemical engineering to develop basic biological functional modules, and through rational design, develop man-made biological systems that have predicted useful functions. Here, we discuss an important principle in rational design of functional biological circuits: the reverse engineering design. We will use a research project that was conducted at Peking University for the International Genetic Engineering Machine Competition (iGEM) to illustrate the principle: synthesis a cell which has a semi-log dose-response to the environment. Through this work we try to demonstrate the potential application of network engineering in synthetic biology.

  16. Earth Science Missions Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Marius, Julio L.

    2009-01-01

    This presentation gives a general overlook of the engineering efforts that are necessary to meet science mission requirement especially for Earth Science missions. It provides brief overlook of NASA's current missions and future Earth Science missions and the engineering challenges to meet some of the specific science objectives. It also provides, if time permits, a brief summary of two significant weather and climate phenomena in the Southern Hemisphere: El Nino and La Nina, as well as the Ozone depletion over Antarctica that will be of interest to IEEE intercom 2009 conference audience.

  17. Integrated reverse engineering and machining system

    NASA Astrophysics Data System (ADS)

    Li, Jianjun; Chow, Joe; Chen, Chinsheng; Xu, TianDi; Tsai, David; Xue, Weidong

    1998-10-01

    This paper deals with the integration of reverse engineering with CAM for duplicating an existing part without a CAD model quickly and accurately. Two commercial packages, SURFACER and SmartCAM, were selected as the software tools for reverse engineering and NC code generation respectively. By utilizing the open architecture environment provided by SURFACER, a machining-oriented feature model can be constructed during the model creation phase. This model consists of not only the part's geometric entities but also all the machining information required for toolpath generation. Upon a knowledge-based process planning, this machining-oriented feature model is converted into a process model, which will then be used to create a job file and a macro file, both in the SmartCAM format. The execution of these two files inside SmartCAM can automatically generate the toolpaths and NC codes required for part machining.

  18. Non-Destructive State Machine Reverse Engineering

    SciTech Connect

    Smith, Jessica L.

    2013-10-10

    Most of the integrated circuits (ICs) that are in electronic systems today are based on state machines. We are taking advantage of this to develop a hardware reverse engineering method that discovers the IC’s underlying state machine, rather than its transistors and gates. While there are other methods for destructively reverse engineering ICs or for non-destructively characterizing ICs, our method offers a fast and accurate analysis while remaining non-destructive. To do this, we present an intelligent brute-force method of exploring the logic of the IC using only the input and outputs designed into the IC - the I/O pins. From this exploration, we can apply a folding algorithm to discover the designed state machine.

  19. Variable Cycle Intake for Reverse Core Engine

    NASA Technical Reports Server (NTRS)

    Suciu, Gabriel L (Inventor); Chandler, Jesse M (Inventor); Staubach, Joseph B (Inventor)

    2016-01-01

    A gas generator for a reverse core engine propulsion system has a variable cycle intake for the gas generator, which variable cycle intake includes a duct system. The duct system is configured for being selectively disposed in a first position and a second position, wherein free stream air is fed to the gas generator when in the first position, and fan stream air is fed to the gas generator when in the second position.

  20. Thrust reverser for high bypass turbofan engine

    SciTech Connect

    Matta, R.K.; Bhutiani, P.K.

    1990-05-08

    This patent describes a thrust reverser for a gas turbine engine of the type which includes an outer wall spaced from the center body of a core engine to define a bypass duct therebetween. The thrust reverser comprising: circumferentially displaced blocker doors, each of the doors being movable between a normal position generally aligned with the outer wall and a thrust reversing position extending transversely of the bypass duct for blocking the exhaust of air through the bypass duct and directing the air through an opening in the outer wall for thrust reversal; each of the blocker doors being of lightweight construction and including a pit in the inner surface thereof in the normal position; means for covering the pit during normal flow of air through the bypass duct to reduce the pressure drop in the bypass duct and to reduce noise. The covering means including a pit cover hingedly mounted at one end thereof on the blocker door and means of biasing the pit cover away from the blocker door to a position providing smooth flow of air through the bypass duct during normal operation.

  1. iSTEM: The Aerospace Engineering Challenge

    ERIC Educational Resources Information Center

    English, Lyn D.; King, Donna T.; Hudson, Peter; Dawes, Les

    2014-01-01

    The authors developed The Paper Plane Challenge as one of a three-part response to The Aerospace Engineering Challenge. The Aerospace Engineering Challenge was the second of three multi-part activities that they had developed with the teachers during the year. Their aim was to introduce students to the exciting world of engineering, where they…

  2. iSTEM: The Aerospace Engineering Challenge

    ERIC Educational Resources Information Center

    English, Lyn D.; King, Donna T.; Hudson, Peter; Dawes, Les

    2014-01-01

    The authors developed The Paper Plane Challenge as one of a three-part response to The Aerospace Engineering Challenge. The Aerospace Engineering Challenge was the second of three multi-part activities that they had developed with the teachers during the year. Their aim was to introduce students to the exciting world of engineering, where they…

  3. Germline engineering: the moral challenges.

    PubMed

    Engelhardt, H Tristram

    2002-03-01

    Not only is the use of germline genetic engineering likely in the long run to be inevitable, there are also no convincing secular moral grounds to forbid this technology in principle. Instead, the general secular moral constraints on the use of germline genetic engineering are either procedural or without predetermined content. Nor can one develop a coherent distinction between eliminating disease and enhancing human abilities. At best, in secular morality one can establish the principle to proceed with care, though the invocation of the precautionary principle argues as much in favor of the development of germline genetic engineering as against its use. Because germline genetic engineering, by eliminating certain genetic defects, offers the prospect of decreasing human suffering and decreasing the use of prenatal diagnosis and abortion, there is an obligation, all else being equal, to change the human genome. In a post-modern world, humans face the challenge of directing their own evolution, although they share no common understanding of human destiny and purpose. Such understandings, though available within religious contexts, are not available to secular bioethics. Copyright 2002 Wiley-Liss, Inc.

  4. Efficient Reverse-Engineering of a Developmental Gene Regulatory Network

    PubMed Central

    Cicin-Sain, Damjan; Ashyraliyev, Maksat; Jaeger, Johannes

    2012-01-01

    Understanding the complex regulatory networks underlying development and evolution of multi-cellular organisms is a major problem in biology. Computational models can be used as tools to extract the regulatory structure and dynamics of such networks from gene expression data. This approach is called reverse engineering. It has been successfully applied to many gene networks in various biological systems. However, to reconstitute the structure and non-linear dynamics of a developmental gene network in its spatial context remains a considerable challenge. Here, we address this challenge using a case study: the gap gene network involved in segment determination during early development of Drosophila melanogaster. A major problem for reverse-engineering pattern-forming networks is the significant amount of time and effort required to acquire and quantify spatial gene expression data. We have developed a simplified data processing pipeline that considerably increases the throughput of the method, but results in data of reduced accuracy compared to those previously used for gap gene network inference. We demonstrate that we can infer the correct network structure using our reduced data set, and investigate minimal data requirements for successful reverse engineering. Our results show that timing and position of expression domain boundaries are the crucial features for determining regulatory network structure from data, while it is less important to precisely measure expression levels. Based on this, we define minimal data requirements for gap gene network inference. Our results demonstrate the feasibility of reverse-engineering with much reduced experimental effort. This enables more widespread use of the method in different developmental contexts and organisms. Such systematic application of data-driven models to real-world networks has enormous potential. Only the quantitative investigation of a large number of developmental gene regulatory networks will allow us to

  5. Efficient reverse-engineering of a developmental gene regulatory network.

    PubMed

    Crombach, Anton; Wotton, Karl R; Cicin-Sain, Damjan; Ashyraliyev, Maksat; Jaeger, Johannes

    2012-01-01

    Understanding the complex regulatory networks underlying development and evolution of multi-cellular organisms is a major problem in biology. Computational models can be used as tools to extract the regulatory structure and dynamics of such networks from gene expression data. This approach is called reverse engineering. It has been successfully applied to many gene networks in various biological systems. However, to reconstitute the structure and non-linear dynamics of a developmental gene network in its spatial context remains a considerable challenge. Here, we address this challenge using a case study: the gap gene network involved in segment determination during early development of Drosophila melanogaster. A major problem for reverse-engineering pattern-forming networks is the significant amount of time and effort required to acquire and quantify spatial gene expression data. We have developed a simplified data processing pipeline that considerably increases the throughput of the method, but results in data of reduced accuracy compared to those previously used for gap gene network inference. We demonstrate that we can infer the correct network structure using our reduced data set, and investigate minimal data requirements for successful reverse engineering. Our results show that timing and position of expression domain boundaries are the crucial features for determining regulatory network structure from data, while it is less important to precisely measure expression levels. Based on this, we define minimal data requirements for gap gene network inference. Our results demonstrate the feasibility of reverse-engineering with much reduced experimental effort. This enables more widespread use of the method in different developmental contexts and organisms. Such systematic application of data-driven models to real-world networks has enormous potential. Only the quantitative investigation of a large number of developmental gene regulatory networks will allow us to

  6. Engineering Innovations for Exploration Challenges

    NASA Technical Reports Server (NTRS)

    Dumbacher, Daniel L.

    2010-01-01

    This slide presentation reviews some of the engineering innovations requirements for the challenges of space exploration which NASA has and will be involved in. It reviews some significant successes in space transportation, exploration and science accomplished during 2009, and it reviews some of the places that are available for exploration in the near term and the specific missions that NASA has assigned to Marshall. It also reviews the project lifecycle management model, that is designed to reduce undefined, but known, risks. It also demonstrates the sustainable long-term program of block upgrades that contribute to long-term success of programs.

  7. High Pressure Reverse Flow APS Engine

    NASA Technical Reports Server (NTRS)

    Senneff, J. M.

    1972-01-01

    A design and test demonstration effort was undertaken to evaluate the concept of the reverse flow engine for the APS engine application. The 1500 lb (6672 N) thrust engine was designed to operate on gaseous hydrogen and gaseous oxygen propellants at a mixture ratio of 4 and to achieve the objective performance of 435 sec (4266 Nsec/kg) specific impulse. Superimposed durability requirements called for a million-cycle capability with 50 hours duration. The program was undertaken as a series of tasks including the initial preliminary design, design of critical test components and finally, the design and demonstration of an altitude engine which could be used interchangeably to examine operating parameters as well as to demonstrate the capability of the concept. The program results are reported with data to indicate that all of the program objectives were met or exceeded within the course of testing on the program. The analysis effort undertaken is also reported in detail and supplemented with test data in some cases where prior definitions could not be made. The results are contained of these analyses as well as the test results conducted throughout the course of the program. Finally, the test data and analytical results were combined to allow recommendations for a flight weight design. This preliminary design effort is also detailed.

  8. A Predictive Approach to Network Reverse-Engineering

    NASA Astrophysics Data System (ADS)

    Wiggins, Chris

    2005-03-01

    A central challenge of systems biology is the ``reverse engineering" of transcriptional networks: inferring which genes exert regulatory control over which other genes. Attempting such inference at the genomic scale has only recently become feasible, via data-intensive biological innovations such as DNA microrrays (``DNA chips") and the sequencing of whole genomes. In this talk we present a predictive approach to network reverse-engineering, in which we integrate DNA chip data and sequence data to build a model of the transcriptional network of the yeast S. cerevisiae capable of predicting the response of genes in unseen experiments. The technique can also be used to extract ``motifs,'' sequence elements which act as binding sites for regulatory proteins. We validate by a number of approaches and present comparison of theoretical prediction vs. experimental data, along with biological interpretations of the resulting model. En route, we will illustrate some basic notions in statistical learning theory (fitting vs. over-fitting; cross- validation; assessing statistical significance), highlighting ways in which physicists can make a unique contribution in data- driven approaches to reverse engineering.

  9. How bioinformatics can help reverse engineer human aging.

    PubMed

    de Magalhães, João Pedro; Toussaint, Olivier

    2004-04-01

    To study human aging is an enormous challenge. The complexity of the aging phenotype and the near impossibility of studying aging directly in humans oblige researchers to resort to models and extrapolations. Computational approaches offer a powerful set of tools to study human aging. In one direction we have data-mining methods, from comparative genomics to DNA microarrays, to retrieve information in large amounts of data. Afterwards, tools from systems biology to reverse engineering algorithms allow researchers to integrate different types of information to increase our knowledge about human aging. Computer methodologies will play a crucial role to reconstruct the genetic network of human aging and the associated regulatory mechanisms.

  10. Reverse engineering of inductive fault current limiters

    NASA Astrophysics Data System (ADS)

    Pina, J. M.; Suárez, P.; Ventim Neves, M.; Álvarez, A.; Rodrigues, A. L.

    2010-06-01

    The inductive fault current limiter is less compact and harder to scale to high voltage networks than the resistive one. Nevertheless, its simple construction and mechanical robustness make it attractive in low voltage grids. Thus, it might be an enabling technology for the advent of microgrids, low voltage networks with dispersed generation, controllable loads and energy storage. A new methodology for reverse engineering of inductive fault current limiters based on the independent analysis of iron cores and HTS cylinders is presented in this paper. Their electromagnetic characteristics are used to predict the devices' hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters' components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models' application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

  11. Data requirements of reverse-engineering algorithms.

    PubMed

    Just, Winfried

    2007-12-01

    Data Sets used in reverse engineering of biochemical networks contain usually relatively few high-dimensional data points, which makes the problem in general vastly underdetermined. It is therefore important to estimate the probability that a given algorithm will return a model of acceptable quality when run on a data set of small size but high dimension. We propose a mathematical framework for investigating such questions. We then demonstrate that without assuming any prior biological knowledge, in general no theoretical distinction between the performance of different algorithms can be made. We also give an example of how expected algorithm performance can in principle be altered by utilizing certain features of the data collection protocol. We conclude with some examples of theorems that were proven within the proposed framework.

  12. System Engineering Challenges of Future Space Missions

    NASA Technical Reports Server (NTRS)

    Hyde, Tristam Tupper

    2005-01-01

    A viewgraph presentation on the system engineering challenges that face NASA's future space missions is shown. The topics include: 1) Future Space Missions; 2) Trends; and 3) Developing System Engineers.

  13. Reverse thrust performance of the QCSEE variable pitch turbofan engine

    NASA Technical Reports Server (NTRS)

    Samanich, N. E.; Reemsnyder, D. C.; Blodmer, H. E.

    1980-01-01

    Results of steady state reverse and forward to reverse thrust transient performance tests are presented. The original quiet, clean, short haul, experimental engine four segment variable fan nozzle was retested in reverse and compared with a continuous, 30 deg half angle conical exlet. Data indicated that the significantly more stable, higher pressure recovery flow with the fixed 30 deg exlet resulted in lower engine vibrations, lower fan blade stress, and approximately a 20 percent improvement in reverse thrust. Objective reverse thrust of 35 percent of takeoff thrust was reached. Thrust response of less than 1.5 sec was achieved for the approach and the takeoff to reverse thrust transients.

  14. Reverse engineering of pelvic bone for hip joint replacement.

    PubMed

    Popov, I; Onuh, S O

    2009-01-01

    Research into fabrication of hip joint replacements combines knowledge from distinct domains, such as engineering, materials and medical fields. Recent computer assisted technologies have played an important role in the medical field. Unlike the modelling of most of the human bones, the creation of an accurate 3D model of a pelvic bone has been a challenging task. The main source of difficulties in this case has proven to be the complexity of the structure of the pelvis, having basically a free-form shape with a hole in the middle constituting some over-shadowed areas (undercuts), various cavities, areas with high form curvature, variable wall thickness with some very thin sections and inside layers with different mechanical properties. In this research work, a pelvic bone is generated using reverse engineering, rapid prototyping and rapid tooling techniques. The geometric data obtained from reverse engineering through laser scanning are used and manipulated to create accurate 3D CAD representations of these devices. These CAD models can be used for various virtual tests and simulations, as well as for reproduction through rapid manufacturing processes and then used as prototypes in tooling, physical tests and planning of surgical operations.

  15. Liquid rocket engine test facility engineering challenges

    NASA Astrophysics Data System (ADS)

    Ellerbrock, Hartwig; Ziegenhagen, Stefan

    2006-12-01

    Liquid rocket engines for launch vehicles and space crafts as well as their subsystems need to be verified and qualified during hot-runs. A high test cadence combined with a flexible test team helps to reduce the cost for test verification during development/qualification as well as during acceptance testing for production. Test facility intelligence allows to test subsystems in the same manner as during complete engine system tests and will therefore reduce development time and cost. This paper gives an overview of the maturing of test engineering know how for rocket engine test stands as well as high altitude test stands for small propulsion thrusters at EADS-ST in Ottobrunn and Lampoldshausen and is split into two parts: Part 1 gives a historical overview of the EADS-ST test stands at Ottobrunn and Lampoldshausen since the beginning of Rocket propulsion activities in the 1960s. Part 2 gives an overview of the actual test capabilities and the test engineering know-how for test stand construction/adaptation and their use during running programs. Examples of actual realised facility concepts are given to demonstrate cost saving potential for test programs in both cases for development/qualification issues as well as for production purposes.

  16. Incorporating Engineering Design Challenges into STEM Courses

    ERIC Educational Resources Information Center

    Householder, Daniel L., Ed.; Hailey, Christine E., Ed.

    2012-01-01

    Successful strategies for incorporating engineering design challenges into science, technology, engineering, and mathematics (STEM) courses in American high schools are presented in this paper. The developers have taken the position that engineering design experiences should be an important component of the high school education of all American…

  17. Making Recycled Paper: An Engineering Design Challenge

    ERIC Educational Resources Information Center

    Song, Ting; Becker, Kurt

    2013-01-01

    Science, technology, engineering, and mathematics (STEM) educators are facing the challenge of attracting more students. The disparity between the need for engineers and the enrollment of engineering students is growing (Genalo, Bruning, & Adams, 2000), and career aspirations of high school students are inconsistent with the employment…

  18. Making Recycled Paper: An Engineering Design Challenge

    ERIC Educational Resources Information Center

    Song, Ting; Becker, Kurt

    2013-01-01

    Science, technology, engineering, and mathematics (STEM) educators are facing the challenge of attracting more students. The disparity between the need for engineers and the enrollment of engineering students is growing (Genalo, Bruning, & Adams, 2000), and career aspirations of high school students are inconsistent with the employment…

  19. Reversible gelation of genetically engineered macromolecules

    NASA Astrophysics Data System (ADS)

    Petka, Wendy Ann

    Genetic engineering of protein-based polymers offers distinct advantages over conventional synthesis of polymers. Microorganisms can synthesize high molecular weight materials, in relatively large quantities, that are inherently stereoregular, monodisperse, and of controlled sequence. In addition, specific secondary and higher order structures are determined by this protein sequence. As a result, scientists can design polymers to have unique structural features found in natural protein materials and functional properties that are inherent in certain peptide sequences. For this reason, genetic engineering principles were used to create a set of artificial genes that encode twelve macromolecules having both alpha-helical and disordered coil protein sequences with the last amino acid being cysteine (cys) or tryptophan (trp). Triblock copolymer sequences having coiled-coil protein ends, A or B, where A and B represent alpha-helical acidic and basic leucine zipper proteins, separated by a water soluble flexible spacer coil protein, C, where C represents ((AG)sb3PEG) sbn (n = 10 or 28), showed reversible physical gelation behavior. This behavior is believed to result from the aggregation of two or more helices that form physical crosslinks with the disordered coil domain retaining solvent and preventing precipitation of the chain. Diffising wave spectroscopy was used to investigate the gelation behavior of ACsb{10}Acys in buffer when environmental conditions such as pH, temperature, and concentration were varied. The dynamic intensity autocorrelation function recorded over time for 5% (w/v) ACsb{10}Acys showed that the protein behaved as a gel at pH 6.7-8.0 and that the melting point was between 40sp°C and 48sp°C. In addition to the triblock results, the incorporation of 5sp',5sp',5sp'-trifluoroleucine (Tfl) in place of leucine (Leu) in the A and B blocks was accomplished by synthesizing proteins in bacterial hosts auxotrophic for Leu. The substitution of Tfl for Leu

  20. Reverse thrust performance of the QCSEE variable pitch turbofan engine

    NASA Technical Reports Server (NTRS)

    Samanich, N. E.; Reemsnyder, D. C.; Bloomer, H. E.

    1980-01-01

    Results of steady-state reverse and forward-to-reverse thrust transient performance tests are presented. The original QCSEE 4-segment variable fan nozzle was retested in reverse and compared with a continuous, 30-deg half-angle conical exlet. Data indicated that the significantly more stable, higher pressure recovery flow with the fixed 30-deg exlet resulted in lower engine vibrations, lower fan blade stress and approximately a 20% improvement in reverse thrust. Objective reverse thrust of 35% of takeoff thrust was reached. Thrust response of less than 1.5 sec was achieved for the approach and the takeoff-to-reverse thrust transients.

  1. NASA Now: Shuttle Engineering Challenge

    NASA Image and Video Library

    In this installment of NASA Now, you’ll meet Guidance, Navigation and Flight Controls engineer George Hatcher, who talks about the complex system needed to fly the space shuttle at extreme speeds...

  2. Reverse Engineering Cellular Networks with Information Theoretic Methods

    PubMed Central

    Villaverde, Alejandro F.; Ross, John; Banga, Julio R.

    2013-01-01

    Building mathematical models of cellular networks lies at the core of systems biology. It involves, among other tasks, the reconstruction of the structure of interactions between molecular components, which is known as network inference or reverse engineering. Information theory can help in the goal of extracting as much information as possible from the available data. A large number of methods founded on these concepts have been proposed in the literature, not only in biology journals, but in a wide range of areas. Their critical comparison is difficult due to the different focuses and the adoption of different terminologies. Here we attempt to review some of the existing information theoretic methodologies for network inference, and clarify their differences. While some of these methods have achieved notable success, many challenges remain, among which we can mention dealing with incomplete measurements, noisy data, counterintuitive behaviour emerging from nonlinear relations or feedback loops, and computational burden of dealing with large data sets. PMID:24709703

  3. Implementing Inclusive Engineering Challenges for Elementary Students

    ERIC Educational Resources Information Center

    Silva Mangiante, Elaine; Moore, Adam

    2015-01-01

    The Next Generation Science Standards emphasize the need to promote equitable opportunities for all students to engage in science and engineering. This article offers eight tips that educators can use to support students of all abilities, including those with special learning needs, to engage in engineering challenges at the elementary level.

  4. Implementing Inclusive Engineering Challenges for Elementary Students

    ERIC Educational Resources Information Center

    Silva Mangiante, Elaine; Moore, Adam

    2015-01-01

    The Next Generation Science Standards emphasize the need to promote equitable opportunities for all students to engage in science and engineering. This article offers eight tips that educators can use to support students of all abilities, including those with special learning needs, to engage in engineering challenges at the elementary level.

  5. Replaying the evolutionary tape: biomimetic reverse engineering of gene networks.

    PubMed

    Marbach, Daniel; Mattiussi, Claudio; Floreano, Dario

    2009-03-01

    In this paper, we suggest a new approach for reverse engineering gene regulatory networks, which consists of using a reconstruction process that is similar to the evolutionary process that created these networks. The aim is to integrate prior knowledge into the reverse-engineering procedure, thus biasing the search toward biologically plausible solutions. To this end, we propose an evolutionary method that abstracts and mimics the natural evolution of gene regulatory networks. Our method can be used with a wide range of nonlinear dynamical models. This allows us to explore novel model types such as the log-sigmoid model introduced here. We apply the biomimetic method to a gold-standard dataset from an in vivo gene network. The obtained results won a reverse engineering competition of the second DREAM conference (Dialogue on Reverse Engineering Assessments and Methods 2007, New York, NY).

  6. 30. 48' MILL STEAM ENGINE CRANKSHAFT, BALANCE WHEEL, AND REVERSING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. 48' MILL STEAM ENGINE CRANKSHAFT, BALANCE WHEEL, AND REVERSING MECHANISM. Martin Stupich, Photographer, 1989. - U.S. Steel Homestead Works, 48" Plate Mill, Along Monongahela River, Homestead, Allegheny County, PA

  7. Evolutionary Algorithm Based Automated Reverse Engineering and Defect Discovery

    DTIC Science & Technology

    2007-09-21

    A data mining based procedure for automated reverse engineering and defect discovery has been developed. The data mining algorithm for reverse...engineering uses a genetic program (GP) as a data mining function. A GP is an evolutionary algorithm that automatically evolves populations of computer...are used to create a fitness function for the GP, allowing GP-based data mining . This procedure incorporates not only the experts’ rules into the

  8. University Engineering Design Challenge Program

    DTIC Science & Technology

    2014-11-04

    Universities utilizing engineering seniors to bring design solution ideas to AFOSR as well as bring a structured design program for the students . Each year...up to the point where the concrete silo and hged to the point the nail gun could not penetrate the concrete. Our lift worked for the students , but...was not sufficiently powered to carry the appropriate weight. Although not as successful as we had hoped, the students gained a very good

  9. Engineering Encounters: The Tightrope Challenge

    ERIC Educational Resources Information Center

    Burton, Bill

    2014-01-01

    In order to prepare students to become the next innovators, teachers need to provide real-world challenges that allow children to exercise their innovation muscles. Innovation starts with a problem and innovators work to solve a problem by planning, creating, and testing. The real-world innovation process does not happen on a worksheet, and it…

  10. Engineering Encounters: The Tightrope Challenge

    ERIC Educational Resources Information Center

    Burton, Bill

    2014-01-01

    In order to prepare students to become the next innovators, teachers need to provide real-world challenges that allow children to exercise their innovation muscles. Innovation starts with a problem and innovators work to solve a problem by planning, creating, and testing. The real-world innovation process does not happen on a worksheet, and it…

  11. Genetic engineering of rotaviruses by reverse genetics.

    PubMed

    Komoto, Satoshi; Taniguchi, Koki

    2013-07-01

    The rotavirus genome is composed of 11 gene segments of dsRNA. A recent breakthrough in the field of rotaviruses is the development of a reverse genetics system for generating recombinant rotaviruses possessing a gene segment derived from cloned cDNA. Although this approach is a helper virus-driven system that is technically limited and gives low levels of recombinant viruses, it allows alteration of the rotavirus genome, thus contributing to our understanding of these medically important viruses. So far, this approach has successfully been applied to three of the 11 viral segments in our laboratory and others, and the efficiency of recovery of recombinant viruses has been improved. However, we are still waiting for the development of a helper virus-free reverse genetics system for generating an infectious rotavirus entirely from cDNAs, as has been achieved for other members of the Reoviridae family.

  12. University of Minnesota Duluth Engineering Design Challenge

    DTIC Science & Technology

    2015-03-23

    with the flammability of hydraulic fluid and unsuccessful resolution to supporting the device in case of leaks or failures . Figure 39: Hydraulic ...AFRL-OSR-VA-TR-2015-0077 University of Minnesota Duluth Engineering Design Challenge Bill Pederson REGENTS OF THE UNIVERSITY OF MINNESOTA MINNEAPOLIS...Final Performance 3.  DATES COVERED (From - To)      30-09-2011 to 29-09-2014 4.  TITLE AND SUBTITLE University of Minnesota Duluth Engineering Design

  13. Pollution Monitoring: An Engineering Challenge

    NASA Technical Reports Server (NTRS)

    Snodgrass, J. M.

    1971-01-01

    One purpose in presenting this material is to bring to the attention of engineers background material which they would not normally encounter in the course of routine development work. An excellent and timely reference is as follows: Seminar on Methods of Detection, Measurement and Monitoring of Pollutants in the Marine Environment. The international seminar was organized by FAO with the support of UNESCO, IAEA, SCOR and WMO, and was held in Rome, Italy, 4-10 December 1970. The final report, the title of which was given, is a very thoroughgoing document and certainly a must reference for anyone seriously considering the development of sensors for pollution measurement. Perhaps it would be appropriate to present some exact quotations selected from the referenced document. The quotations follow: 1) "The pressures to develop sensitive and reliable methods come about when those responsible for the management of our environment need an objective evaluation of existing or potential perils." 2) "Nearly all of the Panels concerned with the contaminants identified specific examples of man's waste products which may be leaking to the environment in substantial quantities and for which as yet there are no analytical techniques available ". 3) "Very few analyses for organochlorine pesticides appear to have been carried out on sea water and the panel considered that the present methodology was not capable of detecting, on a routine basis, the quantities of these compounds in open sea waters." and 4) "This corresponds essentially to the ratio of useful data produced to the labour expended, since instrumentation costs in the long run become negligible."

  14. Pollution Monitoring: An Engineering Challenge

    NASA Technical Reports Server (NTRS)

    Snodgrass, J. M.

    1971-01-01

    One purpose in presenting this material is to bring to the attention of engineers background material which they would not normally encounter in the course of routine development work. An excellent and timely reference is as follows: Seminar on Methods of Detection, Measurement and Monitoring of Pollutants in the Marine Environment. The international seminar was organized by FAO with the support of UNESCO, IAEA, SCOR and WMO, and was held in Rome, Italy, 4-10 December 1970. The final report, the title of which was given, is a very thoroughgoing document and certainly a must reference for anyone seriously considering the development of sensors for pollution measurement. Perhaps it would be appropriate to present some exact quotations selected from the referenced document. The quotations follow: 1) "The pressures to develop sensitive and reliable methods come about when those responsible for the management of our environment need an objective evaluation of existing or potential perils." 2) "Nearly all of the Panels concerned with the contaminants identified specific examples of man's waste products which may be leaking to the environment in substantial quantities and for which as yet there are no analytical techniques available ". 3) "Very few analyses for organochlorine pesticides appear to have been carried out on sea water and the panel considered that the present methodology was not capable of detecting, on a routine basis, the quantities of these compounds in open sea waters." and 4) "This corresponds essentially to the ratio of useful data produced to the labour expended, since instrumentation costs in the long run become negligible."

  15. Some Future Software Engineering Opportunities and Challenges

    NASA Astrophysics Data System (ADS)

    Boehm, Barry

    This paper provides an update and extension of a 2006 paper, “Some Future Trends and Implications for Systems and Software Engineering Processes,” Systems Engineering, Spring 2006. Some of its challenges and opportunities are similar, such as the need to simultaneously achieve high levels of both agility and assurance. Others have emerged as increasingly important, such as the challenges of dealing with ultralarge volumes of data, with multicore chips, and with software as a service. The paper is organized around eight relatively surprise-free trends and two “wild cards” whose trends and implications are harder to foresee. The eight surprise-free trends are:

  16. Bone Tissue Engineering: Recent Advances and Challenges

    PubMed Central

    Amini, Ami R.; Laurencin, Cato T.; Nukavarapu, Syam P.

    2013-01-01

    The worldwide incidence of bone disorders and conditions has trended steeply upward and is expected to double by 2020, especially in populations where aging is coupled with increased obesity and poor physical activity. Engineered bone tissue has been viewed as a potential alternative to the conventional use of bone grafts, due to their limitless supply and no disease transmission. However, bone tissue engineering practices have not proceeded to clinical practice due to several limitations or challenges. Bone tissue engineering aims to induce new functional bone regeneration via the synergistic combination of biomaterials, cells, and factor therapy. In this review, we discuss the fundamentals of bone tissue engineering, highlighting the current state of this field. Further, we review the recent advances of biomaterial and cell-based research, as well as approaches used to enhance bone regeneration. Specifically, we discuss widely investigated biomaterial scaffolds, micro- and nano-structural properties of these scaffolds, and the incorporation of biomimetic properties and/or growth factors. In addition, we examine various cellular approaches, including the use of mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), adult stem cells, induced pluripotent stem cells (iPSCs), and platelet-rich plasma (PRP), and their clinical application strengths and limitations. We conclude by overviewing the challenges that face the bone tissue engineering field, such as the lack of sufficient vascularization at the defect site, and the research aimed at functional bone tissue engineering. These challenges will drive future research in the field. PMID:23339648

  17. Bone tissue engineering: recent advances and challenges.

    PubMed

    Amini, Ami R; Laurencin, Cato T; Nukavarapu, Syam P

    2012-01-01

    The worldwide incidence of bone disorders and conditions has trended steeply upward and is expected to double by 2020, especially in populations where aging is coupled with increased obesity and poor physical activity. Engineered bone tissue has been viewed as a potential alternative to the conventional use of bone grafts, due to their limitless supply and no disease transmission. However, bone tissue engineering practices have not proceeded to clinical practice due to several limitations or challenges. Bone tissue engineering aims to induce new functional bone regeneration via the synergistic combination of biomaterials, cells, and factor therapy. In this review, we discuss the fundamentals of bone tissue engineering, highlighting the current state of this field. Further, we review the recent advances of biomaterial and cell-based research, as well as approaches used to enhance bone regeneration. Specifically, we discuss widely investigated biomaterial scaffolds, micro- and nano-structural properties of these scaffolds, and the incorporation of biomimetic properties and/or growth factors. In addition, we examine various cellular approaches, including the use of mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), adult stem cells, induced pluripotent stem cells (iPSCs), and platelet-rich plasma (PRP), and their clinical application strengths and limitations. We conclude by overviewing the challenges that face the bone tissue engineering field, such as the lack of sufficient vascularization at the defect site, and the research aimed at functional bone tissue engineering. These challenges will drive future research in the field.

  18. Genetic program based data mining to reverse engineer digital logic

    NASA Astrophysics Data System (ADS)

    Smith, James F., III; Nguyen, Thanh Vu H.

    2006-04-01

    A data mining based procedure for automated reverse engineering and defect discovery has been developed. The data mining algorithm for reverse engineering uses a genetic program (GP) as a data mining function. A genetic program is an algorithm based on the theory of evolution that automatically evolves populations of computer programs or mathematical expressions, eventually selecting one that is optimal in the sense it maximizes a measure of effectiveness, referred to as a fitness function. The system to be reverse engineered is typically a sensor. Design documents for the sensor are not available and conditions prevent the sensor from being taken apart. The sensor is used to create a database of input signals and output measurements. Rules about the likely design properties of the sensor are collected from experts. The rules are used to create a fitness function for the genetic program. Genetic program based data mining is then conducted. This procedure incorporates not only the experts' rules into the fitness function, but also the information in the database. The information extracted through this process is the internal design specifications of the sensor. Uncertainty related to the input-output database and the expert based rule set can significantly alter the reverse engineering results. Significant experimental and theoretical results related to GP based data mining for reverse engineering will be provided. Methods of quantifying uncertainty and its effects will be presented. Finally methods for reducing the uncertainty will be examined.

  19. [URETERAL TISSUE ENGINEERING: CHALLENGES AND PROSPECTS].

    PubMed

    Glybochko, P V; Alaev, Ju G; Vinarov, A Z; Butnaru, D V; Titov, A S; Bibikova, E E; Sevostjanova, S I

    2015-01-01

    A broad range of pathologic conditions of the ureter (strictures, obliterations, fistulas, and so on) requiring reconstructive plastic surgery is a challenging urological problem. A variety of approaches to solve the problem indicates the need of searching for new opportunities. A new direction in reconstructive surgery of the ureter is the tissue engineering. Tissue engineering involves the usage of matrices and cells. The matrices can be used both with cultured cells, and without them. This review represents the results of preclinical studies on feasibility of tissue engineering using as a matrix both natural and synthetic materials for different ureter impairments. Presently, there are no data on the use of tissue-engineering for the ureter reconstruction in clinical trials (i.e. involving human subjects). The results of studies presented in the review inspire certain optimism, but ureteral tissue-engineering is a difficult task requiring a balanced approach and well-thought-out design of preclinical studies.

  20. Mechanical Engineering Education and Its Challenges

    NASA Astrophysics Data System (ADS)

    Ow, C. S.; Kanan, M. M.

    2015-09-01

    The paper addresses historical development in Engineering Education in the country, its evolution till present day efforts toward the formation of Professional Engineers (PE). Of particular interest is the proposed recognition of more than one pathways towards PE Certification amongst member countries of the International Engineering Alliance (IEA). However, Engineering Education of Gen Y poses challenges at maintaining relevant benchmarks at the basic degree level. The widespread use of sophisticated software for simulation work in any undergraduate programme has its sacrifices with respect to emphasis on depth of knowledge. A definite mismatch between what is perceived by the educators and the actual performance of graduates had been identified in a forum and an employment survey conducted by the Institution of Engineers Malaysia (IEM). Suggestions as to how this can be addressed include the setting up of a Board of Educators to regulate the education industry.

  1. Reverse engineering of metabolic networks, a critical assessment.

    PubMed

    Hendrickx, Diana M; Hendriks, Margriet M W B; Eilers, Paul H C; Smilde, Age K; Hoefsloot, Huub C J

    2011-02-01

    Inferring metabolic networks from metabolite concentration data is a central topic in systems biology. Mathematical techniques to extract information about the network from data have been proposed in the literature. This paper presents a critical assessment of the feasibility of reverse engineering of metabolic networks, illustrated with a selection of methods. Appropriate data are simulated to study the performance of four representative methods. An overview of sampling and measurement methods currently in use for generating time-resolved metabolomics data is given and contrasted with the needs of the discussed reverse engineering methods. The results of this assessment show that if full inference of a real-world metabolic network is the goal there is a large discrepancy between the requirements of reverse engineering of metabolic networks and contemporary measurement practice. Recommendations for improved time-resolved experimental designs are given.

  2. Biomedical engineering at UCT - challenges and opportunities.

    PubMed

    Douglas, Tania S

    2012-03-02

    The biomedical engineering programme at the University of Cape Town has the potential to address some of South Africa's unique public health challenges and to contribute to growth of the local medical device industry, directly and indirectly, through research activities and postgraduate education. Full realisation of this potential requires engagement with the clinical practice environment and with industry.

  3. Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.

    PubMed

    Willing, Ryan; King, Graham J W; Johnson, James A

    2015-11-26

    Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (p<0.001) and -14±2% (p=0.008) using commercially available, bone reverse engineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p<0.006) and -6±1% (p=0.020), and peak contact stresses increased by 75±52% (p>0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics.

  4. Diversification and Challenges of Software Engineering Standards

    NASA Technical Reports Server (NTRS)

    Poon, Peter T.

    1994-01-01

    The author poses certain questions in this paper: 'In the future, should there be just one software engineering standards set? If so, how can we work towards that goal? What are the challenges of internationalizing standards?' Based on the author's personal view, the statement of his position is as follows: 'There should NOT be just one set of software engineering standards in the future. At the same time, there should NOT be the proliferation of standards, and the number of sets of standards should be kept to a minimum.It is important to understand the diversification of the areas which are spanned by the software engineering standards.' The author goes on to describe the diversification of processes, the diversification in the national and international character of standards organizations, the diversification of the professional organizations producing standards, the diversification of the types of businesses and industries, and the challenges of internationalizing standards.

  5. Diversification and Challenges of Software Engineering Standards

    NASA Technical Reports Server (NTRS)

    Poon, Peter T.

    1994-01-01

    The author poses certain questions in this paper: 'In the future, should there be just one software engineering standards set? If so, how can we work towards that goal? What are the challenges of internationalizing standards?' Based on the author's personal view, the statement of his position is as follows: 'There should NOT be just one set of software engineering standards in the future. At the same time, there should NOT be the proliferation of standards, and the number of sets of standards should be kept to a minimum.It is important to understand the diversification of the areas which are spanned by the software engineering standards.' The author goes on to describe the diversification of processes, the diversification in the national and international character of standards organizations, the diversification of the professional organizations producing standards, the diversification of the types of businesses and industries, and the challenges of internationalizing standards.

  6. On the Precarious Path of Reverse Neuro-Engineering

    PubMed Central

    Marom, Shimon; Meir, Ron; Braun, Erez; Gal, Asaf; Kermany, Einat; Eytan, Danny

    2009-01-01

    In this perspective we provide an example for the limits of reverse engineering in neuroscience. We demonstrate that application of reverse engineering to the study of the design principle of a functional neuro-system with a known mechanism, may result in a perfectly valid but wrong induction of the system's design principle. If in the very simple setup we bring here (static environment, primitive task and practically unlimited access to every piece of relevant information), it is difficult to induce a design principle, what are our chances of exposing biological design principles when more realistic conditions are examined? Implications to the way we do Biology are discussed. PMID:19503751

  7. CMS-2 Reverse Engineering and ENCORE/MODEL Integration

    DTIC Science & Technology

    1992-05-01

    14399 S92 6 01 0,68 I. Table of Contents CMS2 Reverse Engineering and NENCORE/MODEL Integration Study Final Report Part I CMS -2 Reverse Engineering...Automated extraction of design information from an existing software system written in CMS -2 can be used to document that system as-built, and that I The...Cadre Technologies Inc.a N00114-91 -C-0240 Final Report May 1992 The key features of the CMS RET system are: *The interactive visual interface to the

  8. Reverse engineering systems models of regulation: discovery, prediction and mechanisms.

    PubMed

    Ashworth, Justin; Wurtmann, Elisabeth J; Baliga, Nitin S

    2012-08-01

    Biological systems can now be understood in comprehensive and quantitative detail using systems biology approaches. Putative genome-scale models can be built rapidly based upon biological inventories and strategic system-wide molecular measurements. Current models combine statistical associations, causative abstractions, and known molecular mechanisms to explain and predict quantitative and complex phenotypes. This top-down 'reverse engineering' approach generates useful organism-scale models despite noise and incompleteness in data and knowledge. Here we review and discuss the reverse engineering of biological systems using top-down data-driven approaches, in order to improve discovery, hypothesis generation, and the inference of biological properties.

  9. Laser ignited engines: progress, challenges and prospects.

    PubMed

    Dearden, Geoff; Shenton, Tom

    2013-11-04

    Laser ignition (LI) has been shown to offer many potential benefits compared to spark ignition (SI) for improving the performance of internal combustion (IC) engines. This paper outlines progress made in recent research on laser ignited IC engines, discusses the potential advantages and control opportunities and considers the challenges faced and prospects for its future implementation. An experimental research effort has been underway at the University of Liverpool (UoL) to extend the stratified speed/load operating region of the gasoline direct injection (GDI) engine through LI research, for which an overview of some of the approaches, testing and results to date are presented. These indicate how LI can be used to improve control of the engine for: leaner operation, reductions in emissions, lower idle speed and improved combustion stability.

  10. Overcoming Challenges in Engineering the Genetic Code.

    PubMed

    Lajoie, M J; Söll, D; Church, G M

    2016-02-27

    Withstanding 3.5 billion years of genetic drift, the canonical genetic code remains such a fundamental foundation for the complexity of life that it is highly conserved across all three phylogenetic domains. Genome engineering technologies are now making it possible to rationally change the genetic code, offering resistance to viruses, genetic isolation from horizontal gene transfer, and prevention of environmental escape by genetically modified organisms. We discuss the biochemical, genetic, and technological challenges that must be overcome in order to engineer the genetic code. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Reverse Engineering Course at Philadelphia University in Jordan

    ERIC Educational Resources Information Center

    Younis, M. Bani; Tutunji, T.

    2012-01-01

    Reverse engineering (RE) is the process of testing and analysing a system or a device in order to identify, understand and document its functionality. RE is an efficient tool in industrial benchmarking where competitors' products are dissected and evaluated for performance and costs. RE can play an important role in the re-configuration and…

  12. Reverse Engineering Course at Philadelphia University in Jordan

    ERIC Educational Resources Information Center

    Younis, M. Bani; Tutunji, T.

    2012-01-01

    Reverse engineering (RE) is the process of testing and analysing a system or a device in order to identify, understand and document its functionality. RE is an efficient tool in industrial benchmarking where competitors' products are dissected and evaluated for performance and costs. RE can play an important role in the re-configuration and…

  13. Teach CAD and Measuring Skills through Reverse Engineering

    ERIC Educational Resources Information Center

    Board, Keith

    2012-01-01

    This article describes a reverse engineering activity that gives students hands-on, minds-on experience with measuring tools, machine parts, and CAD. The author developed this activity to give students an abundance of practical experience with measuring tools. Equally important, it provides a good interface between the virtual world of CAD 3D…

  14. Recognition vs Reverse Engineering in Boolean Concepts Learning

    ERIC Educational Resources Information Center

    Shafat, Gabriel; Levin, Ilya

    2012-01-01

    This paper deals with two types of logical problems--recognition problems and reverse engineering problems, and with the interrelations between these types of problems. The recognition problems are modeled in the form of a visual representation of various objects in a common pattern, with a composition of represented objects in the pattern.…

  15. REAR DETAIL OF RIGHT ENGINE AND WING. THRUST REVERSER REMAINS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REAR DETAIL OF RIGHT ENGINE AND WING. THRUST REVERSER REMAINS OPEN. MECHANICS JONI BAINE (R) AND BILL THEODORE(L) OPEN FLAP CARRIAGE ACCESS WITH AN IMPACT GUN. THEY WILL CHECK TRANSMISSION FLUID AND OIL THE JACK SCREW. AT FAR LEFT UTILITY MECHANICS BEGIN BODY POLISHING. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY

  16. Teach CAD and Measuring Skills through Reverse Engineering

    ERIC Educational Resources Information Center

    Board, Keith

    2012-01-01

    This article describes a reverse engineering activity that gives students hands-on, minds-on experience with measuring tools, machine parts, and CAD. The author developed this activity to give students an abundance of practical experience with measuring tools. Equally important, it provides a good interface between the virtual world of CAD 3D…

  17. The Use of Reverse Engineering to Analyse Student Computer Programs.

    ERIC Educational Resources Information Center

    Vanneste, Philip; And Others

    1996-01-01

    Discusses how the reverse engineering approach can generate feedback on computer programs without the user having any prior knowledge of what the program was designed to do. This approach uses the cognitive model of programming knowledge to interpret both context independent and dependent errors in the same words and concepts as human programmers.…

  18. A gene network simulator to assess reverse engineering algorithms.

    PubMed

    Di Camillo, Barbara; Toffolo, Gianna; Cobelli, Claudio

    2009-03-01

    In the context of reverse engineering of biological networks, simulators are helpful to test and compare the accuracy of different reverse-engineering approaches in a variety of experimental conditions. A novel gene-network simulator is presented that resembles some of the main features of transcriptional regulatory networks related to topology, interaction among regulators of transcription, and expression dynamics. The simulator generates network topology according to the current knowledge of biological network organization, including scale-free distribution of the connectivity and clustering coefficient independent of the number of nodes in the network. It uses fuzzy logic to represent interactions among the regulators of each gene, integrated with differential equations to generate continuous data, comparable to real data for variety and dynamic complexity. Finally, the simulator accounts for saturation in the response to regulation and transcription activation thresholds and shows robustness to perturbations. It therefore provides a reliable and versatile test bed for reverse engineering algorithms applied to microarray data. Since the simulator describes regulatory interactions and expression dynamics as two distinct, although interconnected aspects of regulation, it can also be used to test reverse engineering approaches that use both microarray and protein-protein interaction data in the process of learning. A first software release is available at http://www.dei.unipd.it/~dicamill/software/netsim as an R programming language package.

  19. Performance engineering challenges: the view from RENCI

    NASA Astrophysics Data System (ADS)

    Fowler, R.; Gamblin, T.; Porterfield, A.; Dreher, P.; Huang, S.; Joó, B.

    2008-07-01

    Trends in chip technology and system design are causing a revolution in high-performance computing. The emergence of multicore processor chips, the construction of very large computing systems, and the increasing need to deal with power and energy issues in these systems are three of the most significant changes. We focus on the way that these trends have created a new set of challenges in the area of performance engineering, the measurement, analysis, and tuning of computing systems and applications. We discuss these changes and outline recent work at the Renaissance Computing Institute to meet these challenges.

  20. Advancing Sustainable Surface Engineering: Challenges & Future Opportunities

    DTIC Science & Technology

    2014-11-01

    2013 Noblis , Inc. Advancing Sustainable Surface Engineering: Challenges & Future Opportunities Dr. Jeffrey Marqusee Chief Scientist...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Noblis Inc,3150 Fairview Park Drive,Falls Church,VA...unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 © 2013 Noblis , Inc

  1. Challenges in engineering large customized bone constructs.

    PubMed

    Forrestal, David P; Klein, Travis J; Woodruff, Maria A

    2017-06-01

    The ability to treat large tissue defects with customized, patient-specific scaffolds is one of the most exciting applications in the tissue engineering field. While an increasing number of modestly sized tissue engineering solutions are making the transition to clinical use, successfully scaling up to large scaffolds with customized geometry is proving to be a considerable challenge. Managing often conflicting requirements of cell placement, structural integrity, and a hydrodynamic environment supportive of cell culture throughout the entire thickness of the scaffold has driven the continued development of many techniques used in the production, culturing, and characterization of these scaffolds. This review explores a range of technologies and methods relevant to the design and manufacture of large, anatomically accurate tissue-engineered scaffolds with a focus on the interaction of manufactured scaffolds with the dynamic tissue culture fluid environment. Biotechnol. Bioeng. 2017;114: 1129-1139. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  2. Reverse engineering validation using a benchmark synthetic gene circuit in human cells.

    PubMed

    Kang, Taek; White, Jacob T; Xie, Zhen; Benenson, Yaakov; Sontag, Eduardo; Bleris, Leonidas

    2013-05-17

    Multicomponent biological networks are often understood incompletely, in large part due to the lack of reliable and robust methodologies for network reverse engineering and characterization. As a consequence, developing automated and rigorously validated methodologies for unraveling the complexity of biomolecular networks in human cells remains a central challenge to life scientists and engineers. Today, when it comes to experimental and analytical requirements, there exists a great deal of diversity in reverse engineering methods, which renders the independent validation and comparison of their predictive capabilities difficult. In this work we introduce an experimental platform customized for the development and verification of reverse engineering and pathway characterization algorithms in mammalian cells. Specifically, we stably integrate a synthetic gene network in human kidney cells and use it as a benchmark for validating reverse engineering methodologies. The network, which is orthogonal to endogenous cellular signaling, contains a small set of regulatory interactions that can be used to quantify the reconstruction performance. By performing successive perturbations to each modular component of the network and comparing protein and RNA measurements, we study the conditions under which we can reliably reconstruct the causal relationships of the integrated synthetic network.

  3. Reverse Engineering Validation using a Benchmark Synthetic Gene Circuit in Human Cells

    PubMed Central

    Kang, Taek; White, Jacob T.; Xie, Zhen; Benenson, Yaakov; Sontag, Eduardo; Bleris, Leonidas

    2013-01-01

    Multi-component biological networks are often understood incompletely, in large part due to the lack of reliable and robust methodologies for network reverse engineering and characterization. As a consequence, developing automated and rigorously validated methodologies for unraveling the complexity of biomolecular networks in human cells remains a central challenge to life scientists and engineers. Today, when it comes to experimental and analytical requirements, there exists a great deal of diversity in reverse engineering methods, which renders the independent validation and comparison of their predictive capabilities difficult. In this work we introduce an experimental platform customized for the development and verification of reverse engineering and pathway characterization algorithms in mammalian cells. Specifically, we stably integrate a synthetic gene network in human kidney cells and use it as a benchmark for validating reverse engineering methodologies. The network, which is orthogonal to endogenous cellular signaling, contains a small set of regulatory interactions that can be used to quantify the reconstruction performance. By performing successive perturbations to each modular component of the network and comparing protein and RNA measurements, we study the conditions under which we can reliably reconstruct the causal relationships of the integrated synthetic network. PMID:23654266

  4. Bioengineering challenges for heart valve tissue engineering.

    PubMed

    Sacks, Michael S; Schoen, Frederick J; Mayer, John E

    2009-01-01

    Surgical replacement of diseased heart valves by mechanical and tissue valve substitutes is now commonplace and enhances survival and quality of life for many patients. However, repairs of congenital deformities require very small valve sizes not commercially available. Further, a fundamental problem inherent to the use of existing mechanical and biological prostheses in the pediatric population is their failure to grow, repair, and remodel. It is believed that a tissue engineered heart valve can accommodate many of these requirements, especially those pertaining to somatic growth. This review provides an overview of the field of heart valve tissue engineering, including recent trends, with a focus on the bioengineering challenges unique to heart valves. We believe that, currently, the key bioengineering challenge is to determine how biological, structural, and mechanical factors affect extracellular matrix (ECM) formation and in vivo functionality. These factors are fundamental to any approach toward developing a clinically viable tissue engineered heart valve (TEHV), regardless of the particular approach. Critical to the current approaches to TEHVs is scaffold design, which must simultaneously provide function (valves must function from the time of implant) as well as stress transfer to the new ECM. From a bioengineering point of view, a hierarchy of approaches will be necessary to connect the organ-tissue relationships with underpinning cell and sub-cellular events. Overall, such approaches need to be structured to address these fundamental issues to lay the basis for TEHVs that can be developed and designed according to truly sound scientific and engineering principles.

  5. [Challenge to the desertification reversion in Horqin Sandy Land].

    PubMed

    Zhao, Xue-Yong; Zhang, Chun-Min; Zuo, Xiao-An; Huang, Gang; Huang, Ying-Xin; Luo, Ya-Yong; Wang, Shao-Kun; Qü, Hao

    2009-07-01

    Analyses of the changes in desertified land area, water resource availability, land use, and plant productivity in Horqin Sandy Land in recent 50 years showed that from 1950 to the late 1980s, the land desertification in Horqin Sandy Land had a rapid expansion, but reversed since then. The annual runoff of Xiliaohe River decreased consistently, and in 1999, the middle reach at Tongliao section was dried up. In recent 20 years, the water table of Xihu Lake was decreased by about 10 m, and dried up in 2001. The above-ground biomass of grasslands decreased from 520 g x m(-2) in 1937 to 197 g x m(-2) in 2005. The main cause of these results was the change of land use pattern, i. e., the overuse of water resources for re-vegetation or cropland irrigation. Water resources reduction was the major challenge to the desertification reversion in Horqin Sandy Land.

  6. Osteochondral tissue engineering: current strategies and challenges.

    PubMed

    Nukavarapu, Syam P; Dorcemus, Deborah L

    2013-01-01

    Osteochondral defect management and repair remain a significant challenge in orthopedic surgery. Osteochondral defects contain damage to both the articular cartilage as well as the underlying subchondral bone. In order to repair an osteochondral defect the needs of the bone, cartilage and the bone-cartilage interface must be taken into account. Current clinical treatments for the repair of osteochondral defects have only been palliative, not curative. Tissue engineering has emerged as a potential alternative as it can be effectively used to regenerate bone, cartilage and the bone-cartilage interface. Several scaffold strategies, such as single phase, layered, and recently graded structures have been developed and evaluated for osteochondral defect repair. Also, as a potential cell source, tissue specific cells and progenitor cells are widely studied in cell culture models, as well with the osteochondral scaffolds in vitro and in vivo. Novel factor strategies being developed, including single factor, multi-factor, or controlled factor release in a graded fashion, not only assist bone and cartilage regeneration, but also establish osteochondral interface formation. The field of tissue engineering has made great strides, however further research needs to be carried out to make this strategy a clinical reality. In this review, we summarize current tissue engineering strategies, including scaffold design, bioreactor use, as well as cell and factor based approaches and recent developments for osteochondral defect repair. In addition, we discuss various challenges that need to be addressed in years to come. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Space shuttle main engine: Interactive design challenges

    NASA Technical Reports Server (NTRS)

    Mccarty, J. P.; Wood, B. K.

    1985-01-01

    The operating requirements established by NASA for the SSME were considerably more demanding than those for earlier rocket engines used in the military launch vehicles or Apollo program. The SSME, in order to achieve the high performance, low weight, long life, reusable objectives, embodied technical demands far in excess of its predecessor rocket engines. The requirements dictated the use of high combustion pressure and the staged combustion cycle which maximizes performance through total use of all propellants in the main combustion process. This approach presented a myriad of technical challenges for maximization of performance within attainable state of the art capabilities for operating pressures, operating temperatures and rotating machinery efficiencies. Controlling uniformity of the high pressure turbomachinery turbine temperature environment was a key challenge for thrust level and life capability demanding innovative engineering. New approaches in the design of the components were necessary to accommodate the multiple use, minimum maintenance objectives. Included were the use of line replaceable units to facilitate field maintenance automatic checkout and internal inspection capabilities.

  8. Tissue-Engineered Skeletal Muscle Organoids for Reversible Gene Therapy

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman; DelTatto, Michael; Shansky, Janet; Lemaire, Julie; Chang, Albert; Payumo, Francis; Lee, Peter; Goodyear, Amy; Raven, Latasha

    1996-01-01

    Genetically modified murine skeletal myoblasts were tissue engineered in vitro into organ-like structures (organoids) containing only postmitotic myofibers secreting pharmacological levels of recombinant human growth hormone (rhGH). Subcutaneous organoid Implantation under tension led to the rapid and stable appearance of physiological sera levels of rhGH for up to 12 weeks, whereas surgical removal led to its rapid disappearance. Reversible delivery of bioactive compounds from postimtotic cells in tissue engineered organs has several advantages over other forms of muscle gene therapy.

  9. Tissue-Engineered Skeletal Muscle Organoids for Reversible Gene Therapy

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman; DelTatto, Michael; Shansky, Janet; Lemaire, Julie; Chang, Albert; Payumo, Francis; Lee, Peter; Goodyear, Amy; Raven, Latasha

    1996-01-01

    Genetically modified murine skeletal myoblasts were tissue engineered in vitro into organ-like structures (organoids) containing only postmitotic myoribers secreting pharmacological levels of recombinant human growth hormone (rhGH). Subcutaneous organoid implantation under tension led to the rapid and stable appearance of physiological sera levels of rhGH for up to 12 weeks, whereas surgical removal led to its rapid disappearance. Reversible delivery of bioactive compounds from postmitotic cells in tissue engineered organs has several advantages over other forms of muscle gene therapy.

  10. Reverse engineering chemical structures from molecular descriptors : how many solutions?

    SciTech Connect

    Brown, William Michael; Martin, Shawn Bryan; Faulon, Jean-Loup Michel

    2005-06-01

    Physical, chemical and biological properties are the ultimate information of interest for chemical compounds. Molecular descriptors that map structural information to activities and properties are obvious candidates for information sharing. In this paper, we consider the feasibility of using molecular descriptors to safely exchange chemical information in such a way that the original chemical structures cannot be reverse engineered. To investigate the safety of sharing such descriptors, we compute the degeneracy (the number of structure matching a descriptor value) of several 2D descriptors, and use various methods to search for and reverse engineer structures. We examine degeneracy in the entire chemical space taking descriptors values from the alkane isomer series and the PubChem database. We further use a stochastic search to retrieve structures matching specific topological index values. Finally, we investigate the safety of exchanging of fragmental descriptors using deterministic enumeration.

  11. Reverse engineering: algebraic boundary representations to constructive solid geometry.

    SciTech Connect

    Buchele, S. F.; Ellingson, W. A.

    1997-12-17

    Recent advances in reverse engineering have focused on recovering a boundary representation (b-rep) of an object, often for integration with rapid prototyping. This boundary representation may be a 3-D point cloud, a triangulation of points, or piecewise algebraic or parametric surfaces. This paper presents work in progress to develop an algorithm to extend the current state of the art in reverse engineering of mechanical parts. This algorithm will take algebraic surface representations as input and will produce a constructive solid geometry (CSG) description that uses solid primitives such as rectangular block, pyramid, sphere, cylinder, and cone. The proposed algorithm will automatically generate a CSG solid model of a part given its algebraic b-rep, thus allowing direct input into a CAD system and subsequent CSG model generation.

  12. Mobile Timekeeping Application Built on Reverse-Engineered JPL Infrastructure

    NASA Technical Reports Server (NTRS)

    Witoff, Robert J.

    2013-01-01

    Every year, non-exempt employees cumulatively waste over one man-year tracking their time and using the timekeeping Web page to save those times. This app eliminates this waste. The innovation is a native iPhone app. Libraries were built around a reverse- engineered JPL API. It represents a punch-in/punch-out paradigm for timekeeping. It is accessible natively via iPhones, and features ease of access. Any non-exempt employee can natively punch in and out, as well as save and view their JPL timecard. This app is built on custom libraries created by reverse-engineering the standard timekeeping application. Communication is through custom libraries that re-route traffic through BrowserRAS (remote access service). This has value at any center where employees track their time.

  13. Reverse engineering gene networks: Integrating genetic perturbations with dynamical modeling

    PubMed Central

    Tegnér, Jesper; Yeung, M. K. Stephen; Hasty, Jeff; Collins, James J.

    2003-01-01

    While the fundamental building blocks of biology are being tabulated by the various genome projects, microarray technology is setting the stage for the task of deducing the connectivity of large-scale gene networks. We show how the perturbation of carefully chosen genes in a microarray experiment can be used in conjunction with a reverse engineering algorithm to reveal the architecture of an underlying gene regulatory network. Our iterative scheme identifies the network topology by analyzing the steady-state changes in gene expression resulting from the systematic perturbation of a particular node in the network. We highlight the validity of our reverse engineering approach through the successful deduction of the topology of a linear in numero gene network and a recently reported model for the segmentation polarity network in Drosophila melanogaster. Our method may prove useful in identifying and validating specific drug targets and in deconvolving the effects of chemical compounds. PMID:12730377

  14. Computer-aided dental prostheses construction using reverse engineering.

    PubMed

    Solaberrieta, E; Minguez, R; Barrenetxea, L; Sierra, E; Etxaniz, O

    2014-01-01

    The implementation of computer-aided design/computer-aided manufacturing (CAD/CAM) systems with virtual articulators, which take into account the kinematics, constitutes a breakthrough in the construction of customised dental prostheses. This paper presents a multidisciplinary protocol involving CAM techniques to produce dental prostheses. This protocol includes a step-by-step procedure using innovative reverse engineering technologies to transform completely virtual design processes into customised prostheses. A special emphasis is placed on a novel method that permits a virtual location of the models. The complete workflow includes the optical scanning of the patient, the use of reverse engineering software and, if necessary, the use of rapid prototyping to produce CAD temporary prostheses.

  15. Reverse engineering of gene regulatory networks: a comparative study.

    PubMed

    Hache, Hendrik; Lehrach, Hans; Herwig, Ralf

    2009-01-01

    Reverse engineering of gene regulatory networks has been an intensively studied topic in bioinformatics since it constitutes an intermediate step from explorative to causative gene expression analysis. Many methods have been proposed through recent years leading to a wide range of mathematical approaches. In practice, different mathematical approaches will generate different resulting network structures, thus, it is very important for users to assess the performance of these algorithms. We have conducted a comparative study with six different reverse engineering methods, including relevance networks, neural networks, and Bayesian networks. Our approach consists of the generation of defined benchmark data, the analysis of these data with the different methods, and the assessment of algorithmic performances by statistical analyses. Performance was judged by network size and noise levels. The results of the comparative study highlight the neural network approach as best performing method among those under study.

  16. Systems biology: the role of engineering in the reverse engineering of biological signaling.

    PubMed

    Iglesias, Pablo A

    2013-05-31

    One of the principle tasks of systems biology has been the reverse engineering of signaling networks. Because of the striking similarities to engineering systems, a number of analysis and design tools from engineering disciplines have been used in this process. This review looks at several examples including the analysis of homeostasis using control theory, the attenuation of noise using signal processing, statistical inference and the use of information theory to understand both binary decision systems and the response of eukaryotic chemotactic cells.

  17. Imaging challenges in biomaterials and tissue engineering.

    PubMed

    Appel, Alyssa A; Anastasio, Mark A; Larson, Jeffery C; Brey, Eric M

    2013-09-01

    Biomaterials are employed in the fields of tissue engineering and regenerative medicine (TERM) in order to enhance the regeneration or replacement of tissue function and/or structure. The unique environments resulting from the presence of biomaterials, cells, and tissues result in distinct challenges in regards to monitoring and assessing the results of these interventions. Imaging technologies for three-dimensional (3D) analysis have been identified as a strategic priority in TERM research. Traditionally, histological and immunohistochemical techniques have been used to evaluate engineered tissues. However, these methods do not allow for an accurate volume assessment, are invasive, and do not provide information on functional status. Imaging techniques are needed that enable non-destructive, longitudinal, quantitative, and three-dimensional analysis of TERM strategies. This review focuses on evaluating the application of available imaging modalities for assessment of biomaterials and tissue in TERM applications. Included is a discussion of limitations of these techniques and identification of areas for further development.

  18. Engineering challenges for detectors at the ILC

    SciTech Connect

    Oriunno, Marco

    2016-05-31

    Over the last years two proposals for experiments at the ILC have been developed, ILD and SID. Extensive R&D has been carried out around the world to develop the needed technologies. Furthermore a first round of engineering studies was made as part of the ILC TDR to understand the integration of these different sub-systems into coherent and integrated detector concepts. Among the key challenges for the sub detectors are the extreme low mass/low power requirements or the extreme channel densities needed in particle flow based detectors. Throughout these studies special care was taken to ensure that the engineering models and the simulation models, used in studies of the physics capabilities of the detectors, stay synchronized. In the near future, the models will need to be evolved to take the special requirements of the potential ILC site in Japan into account. Furthermore, the state of the integration of the detectors, and the future directions, will be discussed.

  19. Cranioplasty prosthesis manufacturing based on reverse engineering technology.

    PubMed

    Chrzan, Robert; Urbanik, Andrzej; Karbowski, Krzysztof; Moskała, Marek; Polak, Jarosław; Pyrich, Marek

    2012-01-01

    Most patients with large focal skull bone loss after craniectomy are referred for cranioplasty. Reverse engineering is a technology which creates a computer-aided design (CAD) model of a real structure. Rapid prototyping is a technology which produces physical objects from virtual CAD models. The aim of this study was to assess the clinical usefulness of these technologies in cranioplasty prosthesis manufacturing. CT was performed on 19 patients with focal skull bone loss after craniectomy, using a dedicated protocol. A material model of skull deficit was produced using computer numerical control (CNC) milling, and individually pre-operatively adjusted polypropylene-polyester prosthesis was prepared. In a control group of 20 patients a prosthesis was manually adjusted to each patient by a neurosurgeon during surgery, without using CT-based reverse engineering/rapid prototyping. In each case, the prosthesis was implanted into the patient. The mean operating times in both groups were compared. In the group of patients with reverse engineering/rapid prototyping-based cranioplasty, the mean operating time was shorter (120.3 min) compared to that in the control group (136.5 min). The neurosurgeons found the new technology particularly useful in more complicated bone deficits with different curvatures in various planes. Reverse engineering and rapid prototyping may reduce the time needed for cranioplasty neurosurgery and improve the prosthesis fitting. Such technologies may utilize data obtained by commonly used spiral CT scanners. The manufacturing of individually adjusted prostheses should be commonly used in patients planned for cranioplasty with synthetic material.

  20. Cranioplasty prosthesis manufacturing based on reverse engineering technology

    PubMed Central

    Chrzan, Robert; Urbanik, Andrzej; Karbowski, Krzysztof; Moskała, Marek; Polak, Jarosław; Pyrich, Marek

    2012-01-01

    Summary Background Most patients with large focal skull bone loss after craniectomy are referred for cranioplasty. Reverse engineering is a technology which creates a computer-aided design (CAD) model of a real structure. Rapid prototyping is a technology which produces physical objects from virtual CAD models. The aim of this study was to assess the clinical usefulness of these technologies in cranioplasty prosthesis manufacturing. Material/Methods CT was performed on 19 patients with focal skull bone loss after craniectomy, using a dedicated protocol. A material model of skull deficit was produced using computer numerical control (CNC) milling, and individually pre-operatively adjusted polypropylene-polyester prosthesis was prepared. In a control group of 20 patients a prosthesis was manually adjusted to each patient by a neurosurgeon during surgery, without using CT-based reverse engineering/rapid prototyping. In each case, the prosthesis was implanted into the patient. The mean operating times in both groups were compared. Results In the group of patients with reverse engineering/rapid prototyping-based cranioplasty, the mean operating time was shorter (120.3 min) compared to that in the control group (136.5 min). The neurosurgeons found the new technology particularly useful in more complicated bone deficits with different curvatures in various planes. Conclusions Reverse engineering and rapid prototyping may reduce the time needed for cranioplasty neurosurgery and improve the prosthesis fitting. Such technologies may utilize data obtained by commonly used spiral CT scanners. The manufacturing of individually adjusted prostheses should be commonly used in patients planned for cranioplasty with synthetic material. PMID:22207125

  1. Engineering Challenges for Closed Ecological System facilities

    NASA Astrophysics Data System (ADS)

    Dempster, William; Nelson, Mark; Allen, John P.

    2012-07-01

    Engineering challenges for closed ecological systems include methods of achieving closure for structures of different materials, and developing methods of allowing energy (for heating and cooling) and information transfer through the materially closed structure. Methods of calculating degree of closure include measuring degradation rates of inert trace gases introduced into the system. An allied problem is developing means of locating where leaks are located so that they may be repaired and degree of closure maintained. Once closure is achieved, methods of dealing with the pressure differentials between inside and outside are needed: from inflatable structures which might adjust to the pressure difference to variable volume chambers attached to the life systems component. These issues are illustrated through the engineering employed at Biosphere 2, the Biosphere 2 Test Module and the Laboratory Biosphere and a discussion of methods used by other closed ecological system facility engineers. Ecological challenges include being able to handle faster cycling rates and accentuated daily and seasonal fluxes of critical life elements such as carbon dioxide, oxygen, water, macro- and mico-nutrients. The problems of achieving sustainability in closed systems for life support include how to handle atmospheric dynamics including trace gases, producing a complete human diet and recycling nutrients and maintaining soil fertility, healthy air and water and preventing the loss of crucial elements from active circulation. In biospheric facilities the challenge is also to produce analogue to natural biomes and ecosystems, studying processes of self-organization and adaptation in systems that allow specification or determination of state variables and cycles which may be followed through all interactions from atmosphere to soils.

  2. Genome Engineering and Agriculture: Opportunities and Challenges.

    PubMed

    Baltes, Nicholas J; Gil-Humanes, Javier; Voytas, Daniel F

    2017-01-01

    In recent years, plant biotechnology has witnessed unprecedented technological change. Advances in high-throughput sequencing technologies have provided insight into the location and structure of functional elements within plant DNA. At the same time, improvements in genome engineering tools have enabled unprecedented control over genetic material. These technologies, combined with a growing understanding of plant systems biology, will irrevocably alter the way we create new crop varieties. As the first wave of genome-edited products emerge, we are just getting a glimpse of the immense opportunities the technology provides. We are also seeing its challenges and limitations. It is clear that genome editing will play an increased role in crop improvement and will help us to achieve food security in the coming decades; however, certain challenges and limitations must be overcome to realize the technology's full potential. © 2017 Elsevier Inc. All rights reserved.

  3. Reverse engineering course at Philadelphia University in Jordan

    NASA Astrophysics Data System (ADS)

    Bani Younis, M.; Tutunji, T.

    2012-03-01

    Reverse engineering (RE) is the process of testing and analysing a system or a device in order to identify, understand and document its functionality. RE is an efficient tool in industrial benchmarking where competitors' products are dissected and evaluated for performance and costs. RE can play an important role in the re-configuration and redesign of legacy and/or undocumented systems. It can also play a key role in helping students understand engineering products. This paper presents the Philadelphia University experience in constructing a RE course and integrating it within the engineering curricula. This paper can be used as a guide to other universities that wish to introduce RE to their curricula. The information provided in this paper covers the RE methodology for a system level, as well as mechanical, electronics and software levels. Finally, samples of student projects are presented in order to show the learning capabilities provided throughout the course.

  4. 14 CFR 25.934 - Turbojet engine thrust reverser system tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Turbojet engine thrust reverser system tests. 25.934 Section 25.934 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet...

  5. 14 CFR 25.934 - Turbojet engine thrust reverser system tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Turbojet engine thrust reverser system tests. 25.934 Section 25.934 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet...

  6. 14 CFR 25.934 - Turbojet engine thrust reverser system tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Turbojet engine thrust reverser system tests. 25.934 Section 25.934 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet...

  7. 14 CFR 25.934 - Turbojet engine thrust reverser system tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Turbojet engine thrust reverser system tests. 25.934 Section 25.934 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet...

  8. 14 CFR 25.934 - Turbojet engine thrust reverser system tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet engine thrust reverser system tests. 25.934 Section 25.934 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet...

  9. Translational Challenges in Cardiovascular Tissue Engineering.

    PubMed

    Emmert, Maximilian Y; Fioretta, Emanuela S; Hoerstrup, Simon P

    2017-04-01

    Valvular heart disease and congenital heart defects represent a major cause of death around the globe. Although current therapy strategies have rapidly evolved over the decades and are nowadays safe, effective, and applicable to many affected patients, the currently used artificial prostheses are still suboptimal. They do not promote regeneration, physiological remodeling, or growth (particularly important aspects for children) as their native counterparts. This results in the continuous degeneration and subsequent failure of these prostheses which is often associated with an increased morbidity and mortality as well as the need for multiple re-interventions. To overcome this problem, the concept of tissue engineering (TE) has been repeatedly suggested as a potential technology to enable native-like cardiovascular replacements with regenerative and growth capacities, suitable for young adults and children. However, despite promising data from pre-clinical and first clinical pilot trials, the translation and clinical relevance of such TE technologies is still very limited. The reasons that currently limit broad clinical adoption are multifaceted and comprise of scientific, clinical, logistical, technical, and regulatory challenges which need to be overcome. The aim of this review is to provide an overview about the translational problems and challenges in current TE approaches. It further suggests directions and potential solutions on how these issues may be efficiently addressed in the future to accelerate clinical translation. In addition, a particular focus is put on the current regulatory guidelines and the associated challenges for these promising TE technologies.

  10. Comparison of reverse-engineering methods using an in silico network.

    PubMed

    Camacho, Diogo; Vera Licona, Paola; Mendes, Pedro; Laubenbacher, Reinhard

    2007-12-01

    The reverse engineering of biochemical networks is a central problem in systems biology. In recent years several methods have been developed for this purpose, using techniques from a variety of fields. A systematic comparison of the different methods is complicated by their widely varying data requirements, making benchmarking difficult. Also, because of the lack of detailed knowledge about most real networks, it is not easy to use experimental data for this purpose. This paper contains a comparison of four reverse-engineering methods using data from a simulated network. The network is sufficiently realistic and complex to include many of the challenges that data from real networks pose. Our results indicate that the two methods based on genetic perturbations of the network outperform the other methods, including dynamic Bayesian networks and a partial correlation method.

  11. The Need and Challenges for Distributed Engine Control

    NASA Technical Reports Server (NTRS)

    Culley, Dennis E.

    2013-01-01

    The presentation describes the challenges facing the turbine engine control system. These challenges are primarily driven by a dependence on commercial electronics and an increasingly severe environment on board the turbine engine. The need for distributed control is driven by the need to overcome these system constraints and develop a new growth path for control technology and, as a result, improved turbine engine performance.

  12. Engineering challenges in biodiesel production from microalgae.

    PubMed

    Aguirre, Ana-Maria; Bassi, Amarjeet; Saxena, Priyanka

    2013-09-01

    In recent years, the not too distant exhaustion of fossil fuels is becoming apparent. Apart from this, the combustion of fossil fuels leads to environmental concerns, the emission of greenhouse gases and issues with global warming and health problems. Production of biodiesel from microalgae may represent an attractive solution to the above mentioned problems, and can offer a renewable source of fuel with fewer pollutants. This review presents a compilation of engineering challenges related to microalgae as a source of biodiesel. Advantages and current limitations for biodiesel production are discussed; some aspects of algae cells biology, with emphasis on cell wall composition, as it represents a barrier for fatty acid extraction and lipid droplets are also presented. In addition, recent advances in the different stages of the manufacturing process are included, starting from the strain selection and finishing in the processing of fatty acids into biodiesel.

  13. Engineering challenges for brain tumor immunotherapy.

    PubMed

    Lyon, Johnathan G; Mokarram, Nassir; Saxena, Tarun; Carroll, Sheridan L; Bellamkonda, Ravi V

    2017-05-15

    Malignant brain tumors represent one of the most devastating forms of cancer with abject survival rates that have not changed in the past 60years. This is partly because the brain is a critical organ, and poses unique anatomical, physiological, and immunological barriers. The unique interplay of these barriers also provides an opportunity for creative engineering solutions. Cancer immunotherapy, a means of harnessing the host immune system for anti-tumor efficacy, is becoming a standard approach for treating many cancers. However, its use in brain tumors is not widespread. This review discusses the current approaches, and hurdles to these approaches in treating brain tumors, with a focus on immunotherapies. We identify critical barriers to immunoengineering brain tumor therapies and discuss possible solutions to these challenges. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  14. Reverse-engineering a detector with false alarms

    NASA Astrophysics Data System (ADS)

    Craver, Scott; Yu, Jun

    2007-02-01

    Inspired by results from the Break Our Watermarking System (BOWS) contest, we explored techniques to reverse-engineer watermarking algorithms via oracle attacks. We exploit a principle called "superrobustness," which allows a watermarking algorithm to be characterized by its resistance to specific distortions. The generic application of this principle to an oracle attack seeks to find a severe false alarm, or a point on the watermark detection region as far as possible from the watermarked image. For specific types of detection regions, these severe false positives can leak information about the feature space as well as detector parameters. We explore the specific case of detectors using normalized correlation, or correlation coefficient.

  15. Variable neighborhood search for reverse engineering of gene regulatory networks.

    PubMed

    Nicholson, Charles; Goodwin, Leslie; Clark, Corey

    2017-01-01

    A new search heuristic, Divided Neighborhood Exploration Search, designed to be used with inference algorithms such as Bayesian networks to improve on the reverse engineering of gene regulatory networks is presented. The approach systematically moves through the search space to find topologies representative of gene regulatory networks that are more likely to explain microarray data. In empirical testing it is demonstrated that the novel method is superior to the widely employed greedy search techniques in both the quality of the inferred networks and computational time.

  16. Engineering Challenges in Antiproton Triggered Fusion Propulsion

    SciTech Connect

    Cassenti, Brice; Kammash, Terry

    2008-01-21

    During the last decade antiproton triggered fusion propulsion has been investigated as a method for achieving high specific impulse, high thrust in a nuclear pulse propulsion system. In general the antiprotons are injected into a pellet containing fusion fuel with a small amount of fissionable material (i.e., an amount less than the critical mass) where the products from the fission are then used to trigger a fusion reaction. Initial calculations and simulations indicate that if magnetically insulated inertial confinement fusion is used that the pellets should result in a specific impulse of between 100,000 and 300,000 seconds at high thrust. The engineering challenges associated with this propulsion system are significant. For example, the antiprotons must be precisely focused. The pellet must be designed to contain the fission and initial fusion products and this will require strong magnetic fields. The fusion fuel must be contained for a sufficiently long time to effectively release the fusion energy, and the payload must be shielded from the radiation, especially the excess neutrons emitted, in addition to many other particles. We will review the recent progress, possible engineering solutions and the potential performance of these systems.

  17. Imaging challenges in biomaterials and tissue engineering

    PubMed Central

    Appel, Alyssa A.; Anastasio, Mark A.; Larson, Jeffery C.; Brey, Eric M.

    2013-01-01

    Biomaterials are employed in the fields of tissue engineering and regenerative medicine (TERM) in order to enhance the regeneration or replacement of tissue function and/or structure. The unique environments resulting from the presence of biomaterials, cells, and tissues result in distinct challenges in regards to monitoring and assessing the results of these interventions. Imaging technologies for three-dimensional (3D) analysis have been identified as a strategic priority in TERM research. Traditionally, histological and immunohistochemical techniques have been used to evaluate engineered tissues. However, these methods do not allow for an accurate volume assessment, are invasive, and do not provide information on functional status. Imaging techniques are needed that enable non-destructive, longitudinal, quantitative, and three-dimensional analysis of TERM strategies. This review focuses on evaluating the application of available imaging modalities for assessment of biomaterials and tissue in TERM applications. Included is a discussion of limitations of these techniques and identification of areas for further development. PMID:23768903

  18. Engineering challenges for detectors at the ILC

    DOE PAGES

    Oriunno, Marco

    2016-05-31

    Over the last years two proposals for experiments at the ILC have been developed, ILD and SID. Extensive R&D has been carried out around the world to develop the needed technologies. Furthermore a first round of engineering studies was made as part of the ILC TDR to understand the integration of these different sub-systems into coherent and integrated detector concepts. Among the key challenges for the sub detectors are the extreme low mass/low power requirements or the extreme channel densities needed in particle flow based detectors. Throughout these studies special care was taken to ensure that the engineering models andmore » the simulation models, used in studies of the physics capabilities of the detectors, stay synchronized. In the near future, the models will need to be evolved to take the special requirements of the potential ILC site in Japan into account. Furthermore, the state of the integration of the detectors, and the future directions, will be discussed.« less

  19. Reverse engineering for biologically inspired cognitive architectures: a critical analysis.

    PubMed

    Schierwagen, Andreas

    2011-01-01

    Research initiatives on both sides of the Atlantic try to utilize the operational principles of organisms and brains to develop biologically inspired, artificial cognitive systems. This paper describes the standard way bio-inspiration is gained, i.e. decompositional analysis or reverse engineering. The indisputable complexity of brain and mind raise the issue of whether they can be understood by applying the standard method. Using Robert Rosen's modeling relation, the scientific analysis method itself is made a subject of discussion. It is concluded that the fundamental assumption of cognitive science, i.e. complex cognitive systems are decomposable, must be abandoned. Implications for investigations of organisms and behavior as well as for engineering artificial cognitive systems are discussed.

  20. Engineering Challenges for Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2011-01-01

    Recent modeling studies on the instability of the debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have underlined the need for active debris removal. A 2009 analysis by the NASA Orbital Debris Program Office shows that, in order to maintain the LEO debris population at a constant level for the next 200 years, an active debris removal of about five objects per year is needed. The targets identified for removal are those with the highest mass and collision probability products in the environment. Many of these objects are spent upper stages with masses ranging from 1 to more than 8 metric tons, residing in several altitude regions and concentrated in about 10 inclination bands. To remove five of those objects on a yearly basis, in a cost-effective manner, represents many challenges in engineering, technology development, and operations. This paper outlines a conceptual end-to-end debris removal operation, including launch, precision tracking, rendezvous, stabilization (of the tumbling targets), capture, and deorbit of the targets; and highlights major challenges associated with the operations. Pros and cons of several proposed removal techniques are also evaluated.

  1. Update of GRASP/Ada reverse engineering tools for Ada

    NASA Technical Reports Server (NTRS)

    Cross, James H., II

    1992-01-01

    The GRASP/Ada project (Graphical Representations of Algorithms, Structures, and Processes for Ada) has successfully created and prototyped a new algorithmic level graphical representation of Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and, as a result, improve reliability and reduce costs. The emphasis was on the automatic generation of the CSD from Ada PDL or source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada source code. In Phase 1 of the GRASP/Ada project, the CSD graphical constructs were created and applied manually to several small Ada programs. A prototype (Version 1) was designed and implemented using FLEX and BISON running under VMS on a VAS 11-780. In Phase 2, the prototype was improved and ported to the Sun 4 platform under UNIX. A user interface was designed and partially implemented using the HP widget toolkit and the X Windows System. In Phase 3, the user interface was extensively reworked using the Athena widget toolkit and X Windows. The prototype was applied successfully to numerous Ada programs ranging in size from several hundred to several thousand lines of source code. Following Phase 3, the prototype was evaluated by software engineering students at Auburn University and then updated with significant enhancements to the user interface including editing capabilities. Version 3.2 of the prototype was prepared for limited distribution to facilitate further evaluation. The current prototype provides the capability for the user to generate CSD's from Ada PDL or source code in a reverse engineering as well as forward engineering mode with a level of flexibility suitable for practical application.

  2. Women in engineering conference: capitalizing on today`s challenges

    SciTech Connect

    Metz, S.S.; Martins, S.M.

    1996-06-01

    This document contains the conference proceedings of the Women in Engineering Conference: Capitalizing on Today`s Challenges, held June 1-4, 1996 in Denver, Colorado. Topics included engineering and science education, career paths, workplace issues, and affirmative action.

  3. Categories in the pigeon brain: A reverse engineering approach.

    PubMed

    Koenen, Charlotte; Pusch, Roland; Bröker, Franziska; Thiele, Samuel; Güntürkün, Onur

    2016-01-01

    Pigeons are well known for their visual capabilities as well as their ability to categorize visual stimuli at both the basic and superordinate level. We adopt a reverse engineering approach to study categorization learning: Instead of training pigeons on predefined categories, we simply present stimuli and analyze neural output in search of categorical clustering on a solely neural level. We presented artificial stimuli, pictorial and grating stimuli, to pigeons without the need of any differential behavioral responding while recording from the nidopallium frontolaterale (NFL), a higher visual area in the avian brain. The pictorial stimuli differed in color and shape; the gratings differed in spatial frequency and amplitude. We computed representational dissimilarity matrices to reveal categorical clustering based on both neural data and pecking behavior. Based on neural output of the NFL, pictorial and grating stimuli were differentially represented in the brain. Pecking behavior showed a similar pattern, but to a lesser extent. A further subclustering within pictorial stimuli according to color and shape, and within gratings according to frequency and amplitude, was not present. Our study gives proof-of-concept that this reverse engineering approach-namely reading out categorical information from neural data--can be quite helpful in understanding the neural underpinnings of categorization learning. © 2015 Society for the Experimental Analysis of Behavior.

  4. Reverse-Engineering Post-Transcriptional Regulation of Gap Genes in Drosophila melanogaster

    PubMed Central

    Becker, Kolja; Balsa-Canto, Eva; Cicin-Sain, Damjan; Hoermann, Astrid; Janssens, Hilde; Banga, Julio R.; Jaeger, Johannes

    2013-01-01

    Systems biology proceeds through repeated cycles of experiment and modeling. One way to implement this is reverse engineering, where models are fit to data to infer and analyse regulatory mechanisms. This requires rigorous methods to determine whether model parameters can be properly identified. Applying such methods in a complex biological context remains challenging. We use reverse engineering to study post-transcriptional regulation in pattern formation. As a case study, we analyse expression of the gap genes Krüppel, knirps, and giant in Drosophila melanogaster. We use detailed, quantitative datasets of gap gene mRNA and protein expression to solve and fit a model of post-transcriptional regulation, and establish its structural and practical identifiability. Our results demonstrate that post-transcriptional regulation is not required for patterning in this system, but is necessary for proper control of protein levels. Our work demonstrates that the uniqueness and specificity of a fitted model can be rigorously determined in the context of spatio-temporal pattern formation. This greatly increases the potential of reverse engineering for the study of development and other, similarly complex, biological processes. PMID:24204230

  5. Reverse-engineering post-transcriptional regulation of gap genes in Drosophila melanogaster.

    PubMed

    Becker, Kolja; Balsa-Canto, Eva; Cicin-Sain, Damjan; Hoermann, Astrid; Janssens, Hilde; Banga, Julio R; Jaeger, Johannes

    2013-10-01

    Systems biology proceeds through repeated cycles of experiment and modeling. One way to implement this is reverse engineering, where models are fit to data to infer and analyse regulatory mechanisms. This requires rigorous methods to determine whether model parameters can be properly identified. Applying such methods in a complex biological context remains challenging. We use reverse engineering to study post-transcriptional regulation in pattern formation. As a case study, we analyse expression of the gap genes Krüppel, knirps, and giant in Drosophila melanogaster. We use detailed, quantitative datasets of gap gene mRNA and protein expression to solve and fit a model of post-transcriptional regulation, and establish its structural and practical identifiability. Our results demonstrate that post-transcriptional regulation is not required for patterning in this system, but is necessary for proper control of protein levels. Our work demonstrates that the uniqueness and specificity of a fitted model can be rigorously determined in the context of spatio-temporal pattern formation. This greatly increases the potential of reverse engineering for the study of development and other, similarly complex, biological processes.

  6. Dialogue on reverse-engineering assessment and methods: the DREAM of high-throughput pathway inference.

    PubMed

    Stolovitzky, Gustavo; Monroe, Don; Califano, Andrea

    2007-12-01

    The biotechnological advances of the last decade have confronted us with an explosion of genetics, genomics, transcriptomics, proteomics, and metabolomics data. These data need to be organized and structured before they may provide a coherent biological picture. To accomplish this formidable task, the availability of an accurate map of the physical interactions in the cell that are responsible for cellular behavior and function would be exceedingly helpful, as these data are ultimately the result of such molecular interactions. However, all we have at this time is, at best, a fragmentary and only partially correct representation of the interactions between genes, their byproducts, and other cellular entities. If we want to succeed in our quest for understanding the biological whole as more than the sum of the individual parts, we need to build more comprehensive and cell-context-specific maps of the biological interaction networks. DREAM, the Dialogue on Reverse Engineering Assessment and Methods, is fostering a concerted effort by computational and experimental biologists to understand the limitations and to enhance the strengths of the efforts to reverse engineer cellular networks from high-throughput data. In this chapter we will discuss the salient arguments of the first DREAM conference. We will highlight both the state of the art in the field of reverse engineering as well as some of its challenges and opportunities.

  7. Combining phage display with de novo protein sequencing for reverse engineering of monoclonal antibodies.

    PubMed

    Rickert, Keith W; Grinberg, Luba; Woods, Robert M; Wilson, Susan; Bowen, Michael A; Baca, Manuel

    2016-01-01

    The enormous diversity created by gene recombination and somatic hypermutation makes de novo protein sequencing of monoclonal antibodies a uniquely challenging problem. Modern mass spectrometry-based sequencing will rarely, if ever, provide a single unambiguous sequence for the variable domains. A more likely outcome is computation of an ensemble of highly similar sequences that can satisfy the experimental data. This outcome can result in the need for empirical testing of many candidate sequences, sometimes iteratively, to identity one which can replicate the activity of the parental antibody. Here we describe an improved approach to antibody protein sequencing by using phage display technology to generate a combinatorial library of sequences that satisfy the mass spectrometry data, and selecting for functional candidates that bind antigen. This approach was used to reverse engineer 2 commercially-obtained monoclonal antibodies against murine CD137. Proteomic data enabled us to assign the majority of the variable domain sequences, with the exception of 3-5% of the sequence located within or adjacent to complementarity-determining regions. To efficiently resolve the sequence in these regions, small phage-displayed libraries were generated and subjected to antigen binding selection. Following enrichment of antigen-binding clones, 2 clones were selected for each antibody and recombinantly expressed as antigen-binding fragments (Fabs). In both cases, the reverse-engineered Fabs exhibited identical antigen binding affinity, within error, as Fabs produced from the commercial IgGs. This combination of proteomic and protein engineering techniques provides a useful approach to simplifying the technically challenging process of reverse engineering monoclonal antibodies from protein material.

  8. Combining phage display with de novo protein sequencing for reverse engineering of monoclonal antibodies

    PubMed Central

    Rickert, Keith W.; Grinberg, Luba; Woods, Robert M.; Wilson, Susan; Bowen, Michael A.; Baca, Manuel

    2016-01-01

    ABSTRACT The enormous diversity created by gene recombination and somatic hypermutation makes de novo protein sequencing of monoclonal antibodies a uniquely challenging problem. Modern mass spectrometry-based sequencing will rarely, if ever, provide a single unambiguous sequence for the variable domains. A more likely outcome is computation of an ensemble of highly similar sequences that can satisfy the experimental data. This outcome can result in the need for empirical testing of many candidate sequences, sometimes iteratively, to identity one which can replicate the activity of the parental antibody. Here we describe an improved approach to antibody protein sequencing by using phage display technology to generate a combinatorial library of sequences that satisfy the mass spectrometry data, and selecting for functional candidates that bind antigen. This approach was used to reverse engineer 2 commercially-obtained monoclonal antibodies against murine CD137. Proteomic data enabled us to assign the majority of the variable domain sequences, with the exception of 3–5% of the sequence located within or adjacent to complementarity-determining regions. To efficiently resolve the sequence in these regions, small phage-displayed libraries were generated and subjected to antigen binding selection. Following enrichment of antigen-binding clones, 2 clones were selected for each antibody and recombinantly expressed as antigen-binding fragments (Fabs). In both cases, the reverse-engineered Fabs exhibited identical antigen binding affinity, within error, as Fabs produced from the commercial IgGs. This combination of proteomic and protein engineering techniques provides a useful approach to simplifying the technically challenging process of reverse engineering monoclonal antibodies from protein material. PMID:26852694

  9. Engineering challenges of ocean alkalinity enhancement

    NASA Astrophysics Data System (ADS)

    Kruger, T.; Renforth, P.

    2012-04-01

    The addition of calcium oxide (CaO) to the ocean as a means of enhancing the capacity of the ocean as a carbon sink was first proposed by Haroon Kheshgi in 1995. Calcium oxide is created by heating high purity limestone in a kiln to temperatures of approximately 1000°C. Addition of this material to the ocean draws carbon dioxide out of the atmosphere (approximately 1 tonne of CaO could sequester 1.3 tonnes of CO2). Abiotic carbonate precipitation is inhibited in the surface ocean. This is a carbon and energy expensive process, where approximately 0.8 tonnes of CO2 are produced at a point source for every tonne sequestered. The feasibility of ocean alkalinity enhancement requires capture and storage of the point source of CO2. We present details of a feasibility study of the engineering challenges of Kheshgi's method focusing on the potential scalability and costs of the proposed process. To draw down a PgC per year would require the extraction and processing of ~6Pg of limestone per year, which is similar in scale to the current coal industry. Costs are estimated at ~USD30-40 per tonne of CO2 sequestered through the process, which is favourable to comparative processes. Kheshgi, H. (1995) Energy 20 (9) 915-922

  10. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

  11. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

  12. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

  13. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

  14. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

  15. Update of GRASP/Ada reverse engineering tools for Ada

    NASA Technical Reports Server (NTRS)

    Cross, James H., II

    1993-01-01

    The GRASP/Ada project (Graphical Representations of Algorithms, Structures, and Processes for Ada) successfully created and prototyped a new algorithmic level graphical representation for Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and, as a result, improve reliability and reduce costs. The emphasis was on the automatic generation of the CSD from Ada PDL or source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional pretty printed Ada source code. In Phase 1 of the GRASP/Ada project, the CSD graphical constructs were created and applied manually to several small Ada programs. A prototype CSD generator (Version 1) was designed and implemented using FLEX and BISON running under VMS on a VAX 11-780. In Phase 2, the prototype was improved and ported to the Sun 4 platform under UNIX. A user interface was designed and partially implemented using the HP widget toolkit and the X Windows System. In Phase 3, the user interface was extensively reworked using the Athena widget toolkit and X Windows. The prototype was applied successfully to numerous Ada programs ranging in size from several hundred to several thousand lines of source code. Following Phase 3,e two update phases were completed. Update'92 focused on the initial analysis of evaluation data collected from software engineering students at Auburn University and the addition of significant enhancements to the user interface. Update'93 (the current update) focused on the statistical analysis of the data collected in the previous update and preparation of Version 3.4 of the prototype for limited distribution to facilitate further evaluation. The current prototype provides the capability for the user to generate CSD's from Ada PDL or source code in a reverse engineering as well as forward engineering mode with a level of flexibility suitable for practical

  16. Reverse engineering of a Hamiltonian by designing the evolution operators

    PubMed Central

    Kang, Yi-Hao; Chen, Ye-Hong; Wu, Qi-Cheng; Huang, Bi-Hua; Xia, Yan; Song, Jie

    2016-01-01

    We propose an effective and flexible scheme for reverse engineering of a Hamiltonian by designing the evolution operators to eliminate the terms of Hamiltonian which are hard to be realized in practice. Different from transitionless quantum driving (TQD), the present scheme is focus on only one or parts of moving states in a D-dimension (D ≥ 3) system. The numerical simulation shows that the present scheme not only contains the results of TQD, but also has more free parameters, which make this scheme more flexible. An example is given by using this scheme to realize the population transfer for a Rydberg atom. The influences of various decoherence processes are discussed by numerical simulation and the result shows that the scheme is fast and robust against the decoherence and operational imperfection. Therefore, this scheme may be used to construct a Hamiltonian which can be realized in experiments. PMID:27444137

  17. [The inlay computer aided design based on reverse engineering technology].

    PubMed

    Liu, Ming-li; Lü, Pei-jun; Wang, Yong; Han, Jing-yun; Zhao, Jian-jiang

    2005-01-01

    This study was to explore a CAD method for constructing occlusal and proximal surfaces of inlays using reverse engineering (RE) software and to develop a CAD software for the inlay fabrication. The dentition model of a volunteer with individual normal occlusion was scanned with a 3D mechanical scanner. The scanned objects were prepared teeth with G. V. Black class I, class II and class VI (MOD) cavities, neighbor teeth, intercuspal position (ICP) record, and functional bite record (or functional generate path, FGP). Inlays were constructed based on RE technology using the database of Chinese normal teeth. The technique guideline of inlay CAD was developed based on RE softwares. Inlays designed with CAD technique showed smooth and continuous contours. The occlusal and proximal contacts of inlay met physiologic demands. It is a feasible method to develop a CAD software for inlay fabrication based on RE software.

  18. Reverse Engineering Nature to Design Biomimetic Total Knee Implants.

    PubMed

    Varadarajan, Kartik Mangudi; Zumbrunn, Thomas; Rubash, Harry E; Malchau, Henrik; Muratoglu, Orhun K; Li, Guoan

    2015-10-01

    While contemporary total knee arthroplasty (TKA) provides tremendous clinical benefits, the normal feel and function of the knee is not fully restored. To address this, a novel design process was developed to reverse engineer "biomimetic" articular surfaces that are compatible with normal soft-tissue envelope and kinematics of the knee. The biomimetic articular surface is created by moving the TKA femoral component along in vivo kinematics of normal knees and carving out the tibial articular surface from a rectangular tibial block. Here, we describe the biomimetic design process. In addition, we utilize geometric comparisons and kinematic simulations to show that; (1) tibial articular surfaces of conventional implants are fundamentally incompatible with normal knee motion, and (2) the anatomic geometry of the biomimetic surface contributes directly to restoration of normal knee kinematics. Such biomimetic implants may enable us to achieve the long sought after goal of a "normal" knee post-TKA surgery.

  19. Reverse engineering of a Hamiltonian by designing the evolution operators

    NASA Astrophysics Data System (ADS)

    Kang, Yi-Hao; Chen, Ye-Hong; Wu, Qi-Cheng; Huang, Bi-Hua; Xia, Yan; Song, Jie

    2016-07-01

    We propose an effective and flexible scheme for reverse engineering of a Hamiltonian by designing the evolution operators to eliminate the terms of Hamiltonian which are hard to be realized in practice. Different from transitionless quantum driving (TQD), the present scheme is focus on only one or parts of moving states in a D-dimension (D ≥ 3) system. The numerical simulation shows that the present scheme not only contains the results of TQD, but also has more free parameters, which make this scheme more flexible. An example is given by using this scheme to realize the population transfer for a Rydberg atom. The influences of various decoherence processes are discussed by numerical simulation and the result shows that the scheme is fast and robust against the decoherence and operational imperfection. Therefore, this scheme may be used to construct a Hamiltonian which can be realized in experiments.

  20. Reverse engineering of a Hamiltonian by designing the evolution operators.

    PubMed

    Kang, Yi-Hao; Chen, Ye-Hong; Wu, Qi-Cheng; Huang, Bi-Hua; Xia, Yan; Song, Jie

    2016-07-22

    We propose an effective and flexible scheme for reverse engineering of a Hamiltonian by designing the evolution operators to eliminate the terms of Hamiltonian which are hard to be realized in practice. Different from transitionless quantum driving (TQD), the present scheme is focus on only one or parts of moving states in a D-dimension (D ≥ 3) system. The numerical simulation shows that the present scheme not only contains the results of TQD, but also has more free parameters, which make this scheme more flexible. An example is given by using this scheme to realize the population transfer for a Rydberg atom. The influences of various decoherence processes are discussed by numerical simulation and the result shows that the scheme is fast and robust against the decoherence and operational imperfection. Therefore, this scheme may be used to construct a Hamiltonian which can be realized in experiments.

  1. Femur Model Reconstruction Based on Reverse Engineering and Rapid Prototyping

    NASA Astrophysics Data System (ADS)

    Tang, Tongming; Zhang, Zheng; Ni, Hongjun; Deng, Jiawen; Huang, Mingyu

    Precise reconstruction of 3D models is fundamental and crucial to the researches of human femur. In this paper we present our approach towards tackling this problem. The surface of a human femur was scanned using a hand-held 3D laser scanner. The data obtained, in the form of point cloud, was then processed using the reverse engineering software Geomagic and the CAD/CAM software CimatronE to reconstruct a digital 3D model. The digital model was then used by the rapid prototyping machine to build a physical model of human femur using 3D printing. The geometric characteristics of the obtained physical model matched that of the original femur. The process of "physical object - 3D data - digital 3D model - physical model" presented in this paper provides a foundation of precise modeling for the digital manufacturing, virtual assembly, stress analysis, and simulated surgery of artificial bionic femurs.

  2. Reversible S-Nitrosylation in an Engineered Azurin

    PubMed Central

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; Hosseinzadeh, Parisa; Marshall, Nicholas M.; Yu, Yang; Robinson, Howard; Nilges, Mark J.

    2016-01-01

    S-nitrosothiols are known as reagents for NO storage and transportation, and as regulators in many physiological processes. While the S-nitrosylation catalyzed by heme proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here we report reversible insertion of NO into a copper-thiolate bond in an engineered copper center in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential via deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine within metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)-S(Cys)NO species. The fast, efficient, and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions. PMID:27325093

  3. Reversible S-nitrosylation in an engineered azurin

    DOE PAGES

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; ...

    2016-04-25

    Here, S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper–thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but alsomore » shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)–S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.« less

  4. Reversible S-nitrosylation in an engineered azurin

    SciTech Connect

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; Hosseinzadeh, Parisa; Marshall, Nicholas M.; Yu, Yang; Robinson, Howard; Nilges, Mark J.; Blackburn, Ninian J.; Solomon, Edward I.; Lu, Yi

    2016-04-25

    Here, S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper–thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)–S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.

  5. Reversible S-nitrosylation in an engineered azurin

    SciTech Connect

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; Hosseinzadeh, Parisa; Marshall, Nicholas M.; Yu, Yang; Robinson, Howard; Nilges, Mark J.; Blackburn, Ninian J.; Solomon, Edward I.; Lu, Yi

    2016-04-25

    S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper–thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)–S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.

  6. Reversible S-nitrosylation in an engineered azurin

    SciTech Connect

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; Hosseinzadeh, Parisa; Marshall, Nicholas M.; Yu, Yang; Robinson, Howard; Nilges, Mark J.; Blackburn, Ninian J.; Solomon, Edward I.; Lu, Yi

    2016-04-25

    Here, S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper–thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)–S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.

  7. Un-Building Blocks: A Model of Reverse Engineering and Applicable Heuristics

    DTIC Science & Technology

    2015-12-01

    DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Reverse engineering is the problem - solving activity that ensues when one takes a...Douglas Moses, Vice Provost for Academic Affairs iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT Reverse engineering is the problem - solving ...following proposed definition: reverse engineering is the problem - solving activity that ensues when one takes a human-made system, in whole or in part, and

  8. Grand challenges in interfacing engineering with life sciences and medicine.

    PubMed

    He, Bin; Baird, Richard; Butera, Robert; Datta, Aniruddha; George, Steven; Hecht, Bruce; Hero, Alfred; Lazzi, Gianluca; Lee, Raphael C; Liang, Jie; Neuman, Michael; Peng, Grace C Y; Perreault, Eric J; Ramasubramanian, Melur; Wang, May D; Wikswo, John; Yang, Guang-Zhong; Zhang, Yuan-Ting

    2013-03-01

    This paper summarizes the discussions held during the First IEEE Life Sciences Grand Challenges Conference, held on October 4-5, 2012, at the National Academy of Sciences, Washington, DC, and the grand challenges identified by the conference participants. Despite tremendous efforts to develop the knowledge and ability that are essential in addressing biomedical and health problems using engineering methodologies, the optimization of this approach toward engineering the life sciences and healthcare remains a grand challenge. The conference was aimed at high-level discussions by participants representing various sectors, including academia, government, and industry. Grand challenges were identified by the conference participants in five areas including engineering the brain and nervous system; engineering the cardiovascular system; engineering of cancer diagnostics, therapeutics, and prevention; translation of discoveries to clinical applications; and education and training. A number of these challenges are identified and summarized in this paper.

  9. Reverse engineering and verification of gene networks: principles, assumptions, and limitations of present methods and future perspectives.

    PubMed

    He, Feng; Balling, Rudi; Zeng, An-Ping

    2009-11-01

    Reverse engineering of gene networks aims at revealing the structure of the gene regulation network in a biological system by reasoning backward directly from experimental data. Many methods have recently been proposed for reverse engineering of gene networks by using gene transcript expression data measured by microarray. Whereas the potentials of the methods have been well demonstrated, the assumptions and limitations behind them are often not clearly stated or not well understood. In this review, we first briefly explain the principles of the major methods, identify the assumptions behind them and pinpoint the limitations and possible pitfalls in applying them to real biological questions. With regard to applications, we then discuss challenges in the experimental verification of gene networks generated from reverse engineering methods. We further propose an optimal experimental design for allocating sampling schedule and possible strategies for reducing the limitations of some of the current reverse engineering methods. Finally, we examine the perspectives for the development of reverse engineering and urge the need to move from revealing network structure to the dynamics of biological systems.

  10. Reverse osmosis desalination: water sources, technology, and today's challenges.

    PubMed

    Greenlee, Lauren F; Lawler, Desmond F; Freeman, Benny D; Marrot, Benoit; Moulin, Philippe

    2009-05-01

    Reverse osmosis membrane technology has developed over the past 40 years to a 44% share in world desalting production capacity, and an 80% share in the total number of desalination plants installed worldwide. The use of membrane desalination has increased as materials have improved and costs have decreased. Today, reverse osmosis membranes are the leading technology for new desalination installations, and they are applied to a variety of salt water resources using tailored pretreatment and membrane system design. Two distinct branches of reverse osmosis desalination have emerged: seawater reverse osmosis and brackish water reverse osmosis. Differences between the two water sources, including foulants, salinity, waste brine (concentrate) disposal options, and plant location, have created significant differences in process development, implementation, and key technical problems. Pretreatment options are similar for both types of reverse osmosis and depend on the specific components of the water source. Both brackish water and seawater reverse osmosis (RO) will continue to be used worldwide; new technology in energy recovery and renewable energy, as well as innovative plant design, will allow greater use of desalination for inland and rural communities, while providing more affordable water for large coastal cities. A wide variety of research and general information on RO desalination is available; however, a direct comparison of seawater and brackish water RO systems is necessary to highlight similarities and differences in process development. This article brings to light key parameters of an RO process and process modifications due to feed water characteristics.

  11. GRASP/Ada 95: Reverse Engineering Tools for Ada

    NASA Technical Reports Server (NTRS)

    Cross, James H., II

    1996-01-01

    The GRASP/Ada project (Graphical Representations of Algorithms, Structures, and Processes for Ada) has successfully created and prototyped an algorithmic level graphical representation for Ada software, the Control Structure Diagram (CSD), and a new visualization for a fine-grained complexity metric called the Complexity Profile Graph (CPG). By synchronizing the CSD and the CPG, the CSD view of control structure, nesting, and source code is directly linked to the corresponding visualization of statement level complexity in the CPG. GRASP has been integrated with GNAT, the GNU Ada 95 Translator to provide a comprehensive graphical user interface and development environment for Ada 95. The user may view, edit, print, and compile source code as a CSD with no discernible addition to storage or computational overhead. The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and, as a result, improve reliability and reduce costs. The emphasis has been on the automatic generation of the CSD from Ada 95 source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada source code. The current update has focused on the design and implementation of a new Motif compliant user interface, and a new CSD generator consisting of a tagger and renderer. The Complexity Profile Graph (CPG) is based on a set of functions that describes the context, content, and the scaling for complexity on a statement by statement basis. When combined graphicafly, the result is a composite profile of complexity for the program unit. Ongoing research includes the development and refinement of the associated functions, and the development of the CPG generator prototype. The current Version 5.0 prototype provides the capability for the user to generate CSDs and CPGs from Ada 95 source code in a reverse engineering as well as forward engineering mode with a level of flexibility suitable for

  12. Reverse engineering the mechanical and molecular pathways in stem cell morphogenesis.

    PubMed

    Lu, Kai; Gordon, Richard; Cao, Tong

    2015-03-01

    The formation of relevant biological structures poses a challenge for regenerative medicine. During embryogenesis, embryonic cells differentiate into somatic tissues and undergo morphogenesis to produce three-dimensional organs. Using stem cells, we can recapitulate this process and create biological constructs for therapeutic transplantation. However, imperfect imitation of nature sometimes results in in vitro artifacts that fail to recapitulate the function of native organs. It has been hypothesized that developing cells may self-organize into tissue-specific structures given a correct in vitro environment. This proposition is supported by the generation of neo-organoids from stem cells. We suggest that morphogenesis may be reverse engineered to uncover its interacting mechanical pathway and molecular circuitry. By harnessing the latent architecture of stem cells, novel tissue-engineering strategies may be conceptualized for generating self-organizing transplants. Copyright © 2013 John Wiley & Sons, Ltd.

  13. Genome-wide analytical approaches for reverse metabolic engineering of industrially relevant phenotypes in yeast.

    PubMed

    Oud, Bart; van Maris, Antonius J A; Daran, Jean-Marc; Pronk, Jack T

    2012-03-01

    Successful reverse engineering of mutants that have been obtained by nontargeted strain improvement has long presented a major challenge in yeast biotechnology. This paper reviews the use of genome-wide approaches for analysis of Saccharomyces cerevisiae strains originating from evolutionary engineering or random mutagenesis. On the basis of an evaluation of the strengths and weaknesses of different methods, we conclude that for the initial identification of relevant genetic changes, whole genome sequencing is superior to other analytical techniques, such as transcriptome, metabolome, proteome, or array-based genome analysis. Key advantages of this technique over gene expression analysis include the independency of genome sequences on experimental context and the possibility to directly and precisely reproduce the identified changes in naive strains. The predictive value of genome-wide analysis of strains with industrially relevant characteristics can be further improved by classical genetics or simultaneous analysis of strains derived from parallel, independent strain improvement lineages.

  14. Genome-wide analytical approaches for reverse metabolic engineering of industrially relevant phenotypes in yeast

    PubMed Central

    Oud, Bart; Maris, Antonius J A; Daran, Jean-Marc; Pronk, Jack T

    2012-01-01

    Successful reverse engineering of mutants that have been obtained by nontargeted strain improvement has long presented a major challenge in yeast biotechnology. This paper reviews the use of genome-wide approaches for analysis of Saccharomyces cerevisiae strains originating from evolutionary engineering or random mutagenesis. On the basis of an evaluation of the strengths and weaknesses of different methods, we conclude that for the initial identification of relevant genetic changes, whole genome sequencing is superior to other analytical techniques, such as transcriptome, metabolome, proteome, or array-based genome analysis. Key advantages of this technique over gene expression analysis include the independency of genome sequences on experimental context and the possibility to directly and precisely reproduce the identified changes in naive strains. The predictive value of genome-wide analysis of strains with industrially relevant characteristics can be further improved by classical genetics or simultaneous analysis of strains derived from parallel, independent strain improvement lineages. PMID:22152095

  15. Challenges Faced by Female-Students in Engineering-Education

    ERIC Educational Resources Information Center

    Madara, Diana Starovoytova; Cherotich, Sharon

    2016-01-01

    Gender-related challenges in learning technical courses are universal phenomenon. These challenges could restrain female students from achieving their fullest potential. The main focus of this study, therefore, is to examine self-recognized challenges faced by undergraduate female students in pursuing engineering at the School of Engineering…

  16. Database Search Engines: Paradigms, Challenges and Solutions.

    PubMed

    Verheggen, Kenneth; Martens, Lennart; Berven, Frode S; Barsnes, Harald; Vaudel, Marc

    2016-01-01

    The first step in identifying proteins from mass spectrometry based shotgun proteomics data is to infer peptides from tandem mass spectra, a task generally achieved using database search engines. In this chapter, the basic principles of database search engines are introduced with a focus on open source software, and the use of database search engines is demonstrated using the freely available SearchGUI interface. This chapter also discusses how to tackle general issues related to sequence database searching and shows how to minimize their impact.

  17. Reverse engineering a hierarchical regulatory network downstream of oncogenic KRAS

    PubMed Central

    Stelniec-Klotz, Iwona; Legewie, Stefan; Tchernitsa, Oleg; Witzel, Franziska; Klinger, Bertram; Sers, Christine; Herzel, Hanspeter; Blüthgen, Nils; Schäfer, Reinhold

    2012-01-01

    RAS mutations are highly relevant for progression and therapy response of human tumours, but the genetic network that ultimately executes the oncogenic effects is poorly understood. Here, we used a reverse-engineering approach in an ovarian cancer model to reconstruct KRAS oncogene-dependent cytoplasmic and transcriptional networks from perturbation experiments based on gene silencing and pathway inhibitor treatments. We measured mRNA and protein levels in manipulated cells by microarray, RT–PCR and western blot analysis, respectively. The reconstructed model revealed complex interactions among the transcriptional and cytoplasmic components, some of which were confirmed by double pertubation experiments. Interestingly, the transcription factors decomposed into two hierarchically arranged groups. To validate the model predictions, we analysed growth parameters and transcriptional deregulation in the KRAS-transformed epithelial cells. As predicted by the model, we found two functional groups among the selected transcription factors. The experiments thus confirmed the predicted hierarchical transcription factor regulation and showed that the hierarchy manifests itself in downstream gene expression patterns and phenotype. PMID:22864383

  18. Automating laser scanning of 3D surfaces for reverse engineering

    NASA Astrophysics Data System (ADS)

    Chan, Vincent H.; Bradley, Colin H.; Vickers, Geoffrey W.

    1997-12-01

    Application of current 3-D laser scanning systems to reverse engineering is limited by two obstacles. The meticulous guidance of the laser scanner over the surface of the object being scanned and the segmentation of the cloud data which is collected by the laser scanner. Presently, both obstacles are being manually solved. The guidance of the laser scanning sensor at the correct surface to sensor distance is dependent on operator judgement and the segmentation of the collected data is reliant on the user to manually define surface boundaries on a computer screen. By applying a 2-D CCD camera, both of these problems can be resolved. Depth information on the location of the object surface can be derived from a pair of stereo images from the CCD camera. Using this depth information, the scanner path can be automatically calculated. Segmentation of the object surface can be accomplished by employing a Kohonen neural network into the CCD image. Successful segmentation of the image is conditional on the locations selected to start neural nodes as well as the prevention of the neuron connectors from bleeding onto neighboring patches. Thus the CCD camera allows for the automatic path planning of the laser scanner as well as the segmentation of the surface into patches defined along its natural boundaries.

  19. Spherical/cylindrical laser scanner for geometric reverse engineering

    NASA Astrophysics Data System (ADS)

    Chan, Vincent H.; Samaan, Medhat

    2004-04-01

    Laser scanners are often used in geometric reverse engineering to generate a CAD drawing out of an existing physical part. This often requires careful path planning to ensure the correct stand-off distance of the sensor, to prevent any collisions of the sensor with the target object and to prevent any scan occlusions in the resulting data. A dedicated system was constructed to collect data using a 3-axis cylindrical/prismatic device. The benefit of this scanning system is the ability to scan completely around the target object, including the bottom of the object. A stripe-type laser diode is used along with a CCD camera. The target object sits on a transparent plexi-glass table, which can be rotated 360 degrees. Both the laser and the CCD are mounted on an arm, such that they can be traversed along a linear path, as well as being rotated 360° around the table. This permits the device to scan in either spherical or cylindrical paths with 360° rotation around the target object. This system allows for the quick scanning of any object while minimizing the number of occlusions in the resulting scan data.

  20. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    This paper discusses the status and application of Computational Fluid Dynamics )CFD) models to address environmental engineering challenges for more detailed understanding of air pollutant source emissions, atmospheric dispersion and resulting human exposure. CFD simulations ...

  1. Wind Energy Status and Future Wind Engineering Challenges: Preprint

    SciTech Connect

    Thresher, R.; Schreck, S.; Robinson, M.; Veers, P.

    2008-08-01

    This paper describes the current status of wind energy technology, the potential for future wind energy development and the science and engineering challenges that must be overcome for the technology to meet its potential.

  2. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    This paper discusses the status and application of Computational Fluid Dynamics )CFD) models to address environmental engineering challenges for more detailed understanding of air pollutant source emissions, atmospheric dispersion and resulting human exposure. CFD simulations ...

  3. Engineering Challenges for Floating Offshore Wind Turbines

    SciTech Connect

    Butterfield, S.; Musial, W.; Jonkman, J.; Sclavounos, P.

    2007-09-01

    The major objective of this paper is to survey the technical challenges that must be overcome to develop deepwater offshore wind energy technologies and to provide a framework from which the first-order economics can be assessed.

  4. The Grand Challenges for Engineering in the 21st

    NASA Astrophysics Data System (ADS)

    Katsouleas, Thomas

    2014-10-01

    The Grand Challenges for Engineering in the 21st century identified by the NAE re-frame the engineering profession in human facing terms rather than in terms of disciplines or devices. Nevertheless, plasmas will play a major role in solving many of these challenges. The challenges involve making the world more sustainable, more healthful, more secure and more joyful. From the challenge of Provide Clean Water (to nearly a billion people who lack regular access to it), to Provide Energy from Fusion and Engineer the Tools of Scientific Discovery, plasmas will play an essential role. This talk highlights progress on the NAE Grand Challenges and the role that plasmas are playing in addressing them. Particular attention will be given to plasma-based particle accelerators and the question of whether they really offer a path to smaller, cheaper accelerators that could impact human health through cancer therapies or enable new discoveries at the high energy frontier.

  5. Student Learning in Challenge-Based Engineering Curricula

    ERIC Educational Resources Information Center

    Berland, Leema K.; Martin, Taylor H.; Ko, Pat; Peacock, Stephanie Baker; Rudolph, Jennifer J.; Golubski, Chris

    2013-01-01

    In recent years, there has been a demand to teach engineering in high schools, particularly using a challenge-based curriculum. Many of these programs have the dual goals of teaching students the engineering design process (EDP), and teaching to deepen their understanding and ability to apply science and math concepts. Using both quantitative and…

  6. Math and Science Teaching Challenges Student Engineers.

    ERIC Educational Resources Information Center

    Ryan, Barbara Haddad

    1985-01-01

    The Colorado School of Mines and the Cherry Creek (Colorado) School District cooperate in a program using engineering students as part-time instructional technicians in mathematics and science for the district. The program provides role models and highly trained support personnel for district students, and helps recruit teachers. (PGD)

  7. Informatics challenges in tissue engineering and biomaterials.

    PubMed

    Rekow, D

    2003-12-01

    Both tissue engineering and biomaterials have made tremendous strides recently, yet major questions remain unanswered. Tissue-engineered products have come to the market; others are in development. A fundamental issue that informatics could address for tissue engineering is to describe and to predict the cascade of biochemical and cellular reactions that occur as a function of time and implant material: surface texture, microporosity; pore size, density, and connectivity; and three-dimensional configuration. Behavior of ceramics, a subset of tissue-engineering scaffold materials and a mainstay of dental restorations, has been studied extensively for very thin layers and for thicknesses greater than 2 mm. Until recently, little has been known about dentally relevant thickness of 1-2 mm. Results have been surprising and are continuing to develop. Still, at least one fundamental question remains that could be addressed by informatics techniques: Where, along the spectrum of flat-polished material to 10-year clinical in vivo study, can we test to predict clinical performance of all-ceramic crowns accurately?

  8. The Crab Boat Engineering Design Challenge

    ERIC Educational Resources Information Center

    Love, Tyler S.; Ryan, Larry

    2017-01-01

    Crab cakes and football, that's what Maryland does!" (Abrams, Levy, Panay, & Dobkin, 2005). Although the Old Line State is notorious for harvesting delectable blue crabs, the movie "Wedding Crashers" failed to highlight something else Maryland does well: engineering design competitions. This article discusses how a multistate…

  9. Optimizing Your K-5 Engineering Design Challenge

    ERIC Educational Resources Information Center

    Coppola, Matthew Perkins; Merz, Alice H.

    2017-01-01

    Today, elementary school teachers continue to revisit old lessons and seek out new ones, especially in engineering. Optimization is the process by which an existing product or procedure is revised and refined. Drawn from the authors' experiences working directly with students in grades K-5 and their teachers and preservice teachers, the…

  10. Optimizing Your K-5 Engineering Design Challenge

    ERIC Educational Resources Information Center

    Coppola, Matthew Perkins; Merz, Alice H.

    2017-01-01

    Today, elementary school teachers continue to revisit old lessons and seek out new ones, especially in engineering. Optimization is the process by which an existing product or procedure is revised and refined. Drawn from the authors' experiences working directly with students in grades K-5 and their teachers and preservice teachers, the…

  11. Math and Science Teaching Challenges Student Engineers.

    ERIC Educational Resources Information Center

    Ryan, Barbara Haddad

    1985-01-01

    The Colorado School of Mines and the Cherry Creek (Colorado) School District cooperate in a program using engineering students as part-time instructional technicians in mathematics and science for the district. The program provides role models and highly trained support personnel for district students, and helps recruit teachers. (PGD)

  12. Reverse engineering and analysis of large genome-scale gene networks.

    PubMed

    Aluru, Maneesha; Zola, Jaroslaw; Nettleton, Dan; Aluru, Srinivas

    2013-01-07

    Reverse engineering the whole-genome networks of complex multicellular organisms continues to remain a challenge. While simpler models easily scale to large number of genes and gene expression datasets, more accurate models are compute intensive limiting their scale of applicability. To enable fast and accurate reconstruction of large networks, we developed Tool for Inferring Network of Genes (TINGe), a parallel mutual information (MI)-based program. The novel features of our approach include: (i) B-spline-based formulation for linear-time computation of MI, (ii) a novel algorithm for direct permutation testing and (iii) development of parallel algorithms to reduce run-time and facilitate construction of large networks. We assess the quality of our method by comparison with ARACNe (Algorithm for the Reconstruction of Accurate Cellular Networks) and GeneNet and demonstrate its unique capability by reverse engineering the whole-genome network of Arabidopsis thaliana from 3137 Affymetrix ATH1 GeneChips in just 9 min on a 1024-core cluster. We further report on the development of a new software Gene Network Analyzer (GeNA) for extracting context-specific subnetworks from a given set of seed genes. Using TINGe and GeNA, we performed analysis of 241 Arabidopsis AraCyc 8.0 pathways, and the results are made available through the web.

  13. Reverse engineering human neurodegenerative disease using pluripotent stem cell technology.

    PubMed

    Liu, Ying; Deng, Wenbin

    2016-05-01

    With the technology of reprogramming somatic cells by introducing defined transcription factors that enables the generation of "induced pluripotent stem cells (iPSCs)" with pluripotency comparable to that of embryonic stem cells (ESCs), it has become possible to use this technology to produce various cells and tissues that have been difficult to obtain from living bodies. This advancement is bringing forth rapid progress in iPSC-based disease modeling, drug screening, and regenerative medicine. More and more studies have demonstrated that phenotypes of adult-onset neurodegenerative disorders could be rather faithfully recapitulated in iPSC-derived neural cell cultures. Moreover, despite the adult-onset nature of the diseases, pathogenic phenotypes and cellular abnormalities often exist in early developmental stages, providing new "windows of opportunity" for understanding mechanisms underlying neurodegenerative disorders and for discovering new medicines. The cell reprogramming technology enables a reverse engineering approach for modeling the cellular degenerative phenotypes of a wide range of human disorders. An excellent example is the study of the human neurodegenerative disease amyotrophic lateral sclerosis (ALS) using iPSCs. ALS is a progressive neurodegenerative disease characterized by the loss of upper and lower motor neurons (MNs), culminating in muscle wasting and death from respiratory failure. The iPSC approach provides innovative cell culture platforms to serve as ALS patient-derived model systems. Researchers have converted iPSCs derived from ALS patients into MNs and various types of glial cells, all of which are involved in ALS, to study the disease. The iPSC technology could be used to determine the role of specific genetic factors to track down what's wrong in the neurodegenerative disease process in the "disease-in-a-dish" model. Meanwhile, parallel experiments of targeting the same specific genes in human ESCs could also be performed to control

  14. Can cancer be reversed by engineering the tumor microenvironment?

    PubMed Central

    Ingber, Donald E.

    2008-01-01

    To advance cancer research in a transformative way, we must redefine the problem. Although epithelial cancers, such as breast cancer, may be caused by random somatic gene mutations, the reality is that this is only one of many ways to induce tumor formation. Cancers also can be produced in experimental systems in vitro and in vivo, for example, by inducing sustained alterations of extracellular matrix (ECM) structure. Moreover, certain epithelial cancers can be induced to ‘reboot’ and regenerate normal tissue morphology when combined with embryonic mesenchyme or exogenous ECM scaffolds that are produced through epithelial-stromal interactions. At the same time, work in the field of Mechanical Biology has revealed that many cell behaviors critical for cancer formation (e.g., growth, differentiation, motility, apoptosis) can be controlled by physical interactions between cells and their ECM adhesions that alter the mechanical force balance in the ECM, cell and cytoskeleton. Epithelial tumor progression also can be induced in vitro by changing ECM mechanics or altering cytoskeletal tension generation through manipulation of the Rho GTPase signaling pathway. Mechanical interactions between capillary cells and ECM that are mediated by Rho signaling similarly mediate control of capillary cell growth and angiogenesis, which are equally critical for cancer progression and metastasis. These findings question basic assumptions in the cancer field, and raise the intriguing possibility that cancer may be a reversible disease that results from progressive deregulation of tissue architecture, which leads to physical changes in cells and altered mechanical signaling. This perspective raises the possibility of developing a tissue engineering approach to cancer therapy in which biologically-inspired materials that mimic the embryonic microenvironment are used to induce cancers to revert into normal tissues. PMID:18472275

  15. Challenges in engineering microbes for biofuels production.

    PubMed

    Stephanopoulos, Gregory

    2007-02-09

    Economic and geopolitical factors (high oil prices, environmental concerns, and supply instability) have been prompting policy-makers to put added emphasis on renewable energy sources. For the scientific community, recent advances, embodied in new insights into basic biology and technology that can be applied to metabolic engineering, are generating considerable excitement. There is justified optimism that the full potential of biofuel production from cellulosic biomass will be obtainable in the next 10 to 15 years.

  16. Engineering natural heart valves: possibilities and challenges.

    PubMed

    Namiri, Mehrnaz; Ashtiani, Mohammad Kazemi; Mashinchian, Omid; Hasani-Sadrabadi, Mohammad Mahdi; Mahmoudi, Morteza; Aghdami, Nasser; Baharvand, Hossein

    2017-05-01

    Heart valve replacement is considered to be the most prevalent treatment approach for cardiac valve-related diseases. Among current solutions for heart valve replacement, e.g. mechanical and bioprosthetic valves, the main shortcoming is the lack of growth capability, repair and remodelling of the substitute valve. During the past three decades, tissue engineering-based approaches have shown tremendous potential to overcome these limitations by the development of a biodegradable scaffold, which provides biomechanical and biochemical properties of the native tissue. Among various scaffolds employed for tissue engineering, the decellularized heart valve (DHV) has attracted much attention, due to its native structure as well as comparable haemodynamic characteristics. Although the human DHV has shown optimal properties for valve replacement, the limitation of valve donors in terms of time and size is their main clinical issue. In this regard, xenogenic DHV can be a promising candidate for heart valve replacement. Xenogenic DHVs have similar composition to human valves, which will overcome the need for human DHVs. The main concern regarding xenogeneic DHV replacement is the immunological reaction and calcification following implantation, weak mechanical properties and insufficient recellularization capacity. In this review, we describe the essential steps required to address these impediments through novel engineering approaches. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Moral status revisited: the challenge of reversed potency.

    PubMed

    Baertschi, Bernard; Mauron, Alexandre

    2010-02-01

    Moral status is a vexing topic. Linked for so long to the unending debates about ensoulment and the morality of abortion, it has recently resurfaced in the embryonic stem cell controversy. In this new context, it should benefit from new insights originating in recent scientific advances. We believe that the recently observed capability of somatic cells to return to a pluripotential state (a capability we propose to name 'reversed potency') in a controlled manner requires us to modify the traditional concept of moral status and to consider it as referring not only to intrinsic properties (like 'to possess reason' or 'to be a person'), but also to extrinsic or relational ones.

  18. Structural Engineering Managers - Innovation Challenges for their Skills

    NASA Astrophysics Data System (ADS)

    Linkeschová, D.; Tichá, A.

    2015-11-01

    The profession of a structural engineer is highly responsible, because the consequences of a structural engineer's errors result not only in economic damage to the property and often irreversible damage to the environment, they can also lead to direct loss of lives. In the current turbulent, dynamically developing society the managerial methods of structural engineers should not stagnate at the level of the last century applications. This paper deals with the challenges which the ongoing century poses to structural engineers and managers. It compares the results of research regarding the current state of managerial skills of structural engineers in Czech building companies to the defined skills of the 21st century's managers according to the global research programme ITL Research and according to the Vision for the Future of Structural Engineering, drawn up by Structural Engineering Institute - SEI ASCE.

  19. Analysis of the reverse jet influence on particle ingestion at the engine inlet

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. Yu.; Pudovikov, D. E.

    2015-06-01

    The reverse mode of an operating near-ground jet engine is considered. The air flow and particle trajectories under the engine intake are calculated. On the base of numerical and theoretical analysis of the air flow and particle trajectories, some conclusions about reducing the probability of transportation of large particles to the engine are drawn.

  20. Bone Tissue Engineering Challenges in Oral & Maxillofacial Surgery.

    PubMed

    Smith, Brandon T; Shum, Jonathan; Wong, Mark; Mikos, Antonios G; Young, Simon

    2015-01-01

    Over the past decades, there has been a substantial amount of innovation and research into tissue engineering and regenerative approaches for the craniofacial region. This highly complex area presents many unique challenges for tissue engineers. Recent research indicates that various forms of implantable biodegradable scaffolds may play a beneficial role in the clinical treatment of craniofacial pathological conditions. Additionally, the direct delivery of bioactive molecules may further increase de novo bone formation. While these strategies offer an exciting glimpse into potential future treatments, there are several challenges that still must be overcome. In this chapter, we will highlight both current surgical approaches for craniofacial reconstruction and recent advances within the field of bone tissue engineering. The clinical challenges and limitations of these strategies will help contextualize and inform future craniofacial tissue engineering strategies.

  1. Technology Transfer Challenges for High-Assurance Software Engineering Tools

    NASA Technical Reports Server (NTRS)

    Koga, Dennis (Technical Monitor); Penix, John; Markosian, Lawrence Z.

    2003-01-01

    In this paper, we describe our experience with the challenges thar we are currently facing in our effort to develop advanced software verification and validation tools. We categorize these challenges into several areas: cost benefits modeling, tool usability, customer application domain, and organizational issues. We provide examples of challenges in each area and identrfj, open research issues in areas which limit our ability to transfer high-assurance software engineering tools into practice.

  2. Technology Transfer Challenges for High-Assurance Software Engineering Tools

    NASA Technical Reports Server (NTRS)

    Koga, Dennis (Technical Monitor); Penix, John; Markosian, Lawrence Z.

    2003-01-01

    In this paper, we describe our experience with the challenges thar we are currently facing in our effort to develop advanced software verification and validation tools. We categorize these challenges into several areas: cost benefits modeling, tool usability, customer application domain, and organizational issues. We provide examples of challenges in each area and identrfj, open research issues in areas which limit our ability to transfer high-assurance software engineering tools into practice.

  3. Hydrogel scaffolds for tissue engineering: Progress and challenges

    PubMed Central

    El-Sherbiny, Ibrahim M.; Yacoub, Magdi H.

    2013-01-01

    Designing of biologically active scaffolds with optimal characteristics is one of the key factors for successful tissue engineering. Recently, hydrogels have received a considerable interest as leading candidates for engineered tissue scaffolds due to their unique compositional and structural similarities to the natural extracellular matrix, in addition to their desirable framework for cellular proliferation and survival. More recently, the ability to control the shape, porosity, surface morphology, and size of hydrogel scaffolds has created new opportunities to overcome various challenges in tissue engineering such as vascularization, tissue architecture and simultaneous seeding of multiple cells. This review provides an overview of the different types of hydrogels, the approaches that can be used to fabricate hydrogel matrices with specific features and the recent applications of hydrogels in tissue engineering. Special attention was given to the various design considerations for an efficient hydrogel scaffold in tissue engineering. Also, the challenges associated with the use of hydrogel scaffolds were described. PMID:24689032

  4. Hydrogel scaffolds for tissue engineering: Progress and challenges.

    PubMed

    El-Sherbiny, Ibrahim M; Yacoub, Magdi H

    2013-01-01

    Designing of biologically active scaffolds with optimal characteristics is one of the key factors for successful tissue engineering. Recently, hydrogels have received a considerable interest as leading candidates for engineered tissue scaffolds due to their unique compositional and structural similarities to the natural extracellular matrix, in addition to their desirable framework for cellular proliferation and survival. More recently, the ability to control the shape, porosity, surface morphology, and size of hydrogel scaffolds has created new opportunities to overcome various challenges in tissue engineering such as vascularization, tissue architecture and simultaneous seeding of multiple cells. This review provides an overview of the different types of hydrogels, the approaches that can be used to fabricate hydrogel matrices with specific features and the recent applications of hydrogels in tissue engineering. Special attention was given to the various design considerations for an efficient hydrogel scaffold in tissue engineering. Also, the challenges associated with the use of hydrogel scaffolds were described.

  5. Toward protein engineering for phytoremediation: possibilities and challenges.

    PubMed

    Jez, Joseph M

    2011-01-01

    The combination of rational protein engineering and directed evolution techniques allow for the redesign of enzymes with tailored properties for use in environmental remediation. This review summarizes current molecular methods for either altering or improving protein function and highlights examples of how these methods can address bioremediation problems. Although much of the protein engineering applied to environmental clean-up employs microbial systems, there is great potential for and significant challenges to translating these approaches to plant systems for phytoremediation purposes. Protein engineering technologies combined with genomic information and metabolic engineering strategies hold promise for the design of plants and microbes to remediate organic and inorganic pollutants.

  6. Solar power satellites: The Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Woodcock, G. R.

    1978-01-01

    Certain elements of solar power satellite design and system engineering studies are reviewed analyzing solar power satellites as a potential baseload electric power source. The complete system concept concept includes not only the satellites and their ground stations, but also the space transportation for delivery of the satellites, piece by piece, into space, and the factories for their construction in space. Issues related to carrying the solar power satellite concept from the present design study phase through implementation of actual hardware are considered. The first issue category is environmental aspects of the SPS systems. The second category of issues is the technology risks associated with achieving the necessary component and subsystem performances. The third category includes the engineering issues associated with carrying out such a large scale project. The fourth issue category is financial: the funding required to bring such a project into being and the costs of the satellites and resulting cost of the power produced as compared to potential alternative energy sources.

  7. Solar power satellites: The Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Woodcock, G. R.

    1978-01-01

    Certain elements of solar power satellite design and system engineering studies are reviewed analyzing solar power satellites as a potential baseload electric power source. The complete system concept concept includes not only the satellites and their ground stations, but also the space transportation for delivery of the satellites, piece by piece, into space, and the factories for their construction in space. Issues related to carrying the solar power satellite concept from the present design study phase through implementation of actual hardware are considered. The first issue category is environmental aspects of the SPS systems. The second category of issues is the technology risks associated with achieving the necessary component and subsystem performances. The third category includes the engineering issues associated with carrying out such a large scale project. The fourth issue category is financial: the funding required to bring such a project into being and the costs of the satellites and resulting cost of the power produced as compared to potential alternative energy sources.

  8. Chemogenomic profiling on a genome-wide scale using reverse-engineered gene networks.

    PubMed

    di Bernardo, Diego; Thompson, Michael J; Gardner, Timothy S; Chobot, Sarah E; Eastwood, Erin L; Wojtovich, Andrew P; Elliott, Sean J; Schaus, Scott E; Collins, James J

    2005-03-01

    A major challenge in drug discovery is to distinguish the molecular targets of a bioactive compound from the hundreds to thousands of additional gene products that respond indirectly to changes in the activity of the targets. Here, we present an integrated computational-experimental approach for computing the likelihood that gene products and associated pathways are targets of a compound. This is achieved by filtering the mRNA expression profile of compound-exposed cells using a reverse-engineered model of the cell's gene regulatory network. We apply the method to a set of 515 whole-genome yeast expression profiles resulting from a variety of treatments (compounds, knockouts and induced expression), and correctly enrich for the known targets and associated pathways in the majority of compounds examined. We demonstrate our approach with PTSB, a growth inhibitory compound with a previously unknown mode of action, by predicting and validating thioredoxin and thioredoxin reductase as its target.

  9. Durability Challenges for Next Generation of Gas Turbine Engine Materials

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    2012-01-01

    Aggressive fuel burn and carbon dioxide emission reduction goals for future gas turbine engines will require higher overall pressure ratio, and a significant increase in turbine inlet temperature. These goals can be achieved by increasing temperature capability of turbine engine hot section materials and decreasing weight of fan section of the engine. NASA is currently developing several advanced hot section materials for increasing temperature capability of future gas turbine engines. The materials of interest include ceramic matrix composites with 1482 - 1648 C temperature capability, advanced disk alloys with 815 C capability, and low conductivity thermal barrier coatings with erosion resistance. The presentation will provide an overview of durability challenges with emphasis on the environmental factors affecting durability for the next generation of gas turbine engine materials. The environmental factors include gaseous atmosphere in gas turbine engines, molten salt and glass deposits from airborne contaminants, impact from foreign object damage, and erosion from ingestion of small particles.

  10. Tendon tissue engineering: progress, challenges, and translation to the clinic.

    PubMed

    Shearn, J T; Kinneberg, K R; Dyment, N A; Galloway, M T; Kenter, K; Wylie, C; Butler, D L

    2011-06-01

    The tissue engineering field has made great strides in understanding how different aspects of tissue engineered constructs (TECs) and the culture process affect final tendon repair. However, there remain significant challenges in developing strategies that will lead to a clinically effective and commercially successful product. In an effort to increase repair quality, a better understanding of normal development, and how it differs from adult tendon healing, may provide strategies to improve tissue engineering. As tendon tissue engineering continues to improve, the field needs to employ more clinically relevant models of tendon injury such as degenerative tendons. We need to translate successes to larger animal models to begin exploring the clinical implications of our treatments. By advancing the models used to validate our TECs, we can help convince our toughest customer, the surgeon, that our products will be clinically efficacious. As we address these challenges in musculoskeletal tissue engineering, the field still needs to address the commercialization of products developed in the laboratory. TEC commercialization faces numerous challenges because each injury and patient is unique. This review aims to provide tissue engineers with a summary of important issues related to engineering tendon repairs and potential strategies for producing clinically successful products.

  11. Tendon Tissue Engineering: Progress, Challenges, and Translation to the Clinic

    PubMed Central

    Shearn, Jason T.; Kinneberg, Kirsten R.C.; Dyment, Nathaniel A.; Galloway, Marc T.; Kenter, Keith; Wylie, Christopher; Butler, David L.

    2013-01-01

    The tissue engineering field has made great strides in understanding how different aspects of tissue engineered constructs (TECs) and the culture process affect final tendon repair. However, there remain significant challenges in developing strategies that will lead to a clinically effective and commercially successful product. In an effort to increase repair quality, a better understanding of normal development, and how it differs from adult tendon healing, may provide strategies to improve tissue engineering. As tendon tissue engineering continues to improve, the field needs to employ more clinically relevant models of tendon injury such as degenerative tendons. We need to translate successes to larger animal models to begin exploring the clinical implications of our treatments. By advancing the models used to validate our TECs, we can help convince our toughest customer, the surgeon, that our products will be clinically efficacious. As we address these challenges in musculoskeletal tissue engineering, the field still needs to address the commercialization of products developed in the laboratory. TEC commercialization faces numerous challenges because each injury and patient is unique. This review aims to provide tissue engineers with a summary of important issues related to engineering tendon repairs and potential strategies for producing clinically successful products. PMID:21625053

  12. [Reverse engineering and rapid prototyping technique for restoration of mandibular bone defect].

    PubMed

    Yang, Juncheng; Zheng, Guangyong

    2009-04-01

    The application principle and procedure of reverse engineering and rapid prototyping techniques are introduced in this paper. The description is concentrated on the applications of the above techniques in medical field, especially in reconstructive surgery of mandibular bone defect.

  13. [The application of the reverse engineering and rapid prototyping technology in the design of respiratory masks].

    PubMed

    Hu, Ming-xi; Gao, Wang-yu; Du, Zheng-jie; Zhang, Yan-jun

    2006-05-01

    The application of the reverse engineering and rapid prototyping technologies in the design of respiratory masks is introduced in this paper. Practice indicates that the technologies can reduce the cost and save the time in product developments.

  14. Reverse engineering by design: using history to teach.

    PubMed

    Fagette, Paul

    2013-01-01

    Engineering students rarely have an opportunity to delve into the historic antecedents of design in their craft, and this is especially true for biomedical devices. The teaching emphasis is always on the new, the innovative, and the future. Even so, over the last decade, I have coupled a research agenda with engineering special projects into a successful format that allows young biomedical engineering students to understand aspects of their history and learn the complexities of design. There is value in having knowledge of historic engineering achievements, not just for an appreciation of these accomplishments but also for understanding exactly how engineers and clinicians of the day executed their feats-in other words, how the design process works. Ultimately, this particular educational odyssey confirms that history and engineering education are not only compatible but mutually supportive.

  15. [Application status of rapid prototyping technology in artificial bone based on reverse engineering].

    PubMed

    Fang, Ao; Zheng, Min; Fan, Ding

    2015-02-01

    Artificial bone replacement has made an important contribution to safeguard human health and improve the quality of life. The application requirements of rapid prototyping technology based on reverse engineering in individualized artificial bone with individual differences are particularly urgent. This paper reviewed the current research and applications of rapid prototyping and reverse engineering in artificial bone. The research developments and the outlook of bone kinematics and dynamics simulation are also introduced.

  16. Reverse Engineering: Strategy to Teach Evidence-Based Practice to Online RN-to-BSN Students.

    PubMed

    Gary, Jodie C; Hudson, Cindy E

    2016-01-01

    This article describes an innovative approach to introducing RN-to-BSN students to nursing research and evidence-based practice (EBP). Reverse engineering updates an existing EBP project to better emphasize the role of research and evidence to practicing RNs enrolled in an RN-to-BSN program. Reverse engineering of a nursing practice guideline offers a method for teaching an appreciation of research and supporting nursing practice with best evidence.

  17. Challenges and opportunities in synthetic biology for chemical engineers

    PubMed Central

    Luo, Yunzi; Lee, Jung-Kul; Zhao, Huimin

    2012-01-01

    Synthetic biology provides numerous great opportunities for chemical engineers in the development of new processes for large-scale production of biofuels, value-added chemicals, and protein therapeutics. However, challenges across all scales abound. In particular, the modularization and standardization of the components in a biological system, so-called biological parts, remain the biggest obstacle in synthetic biology. In this perspective, we will discuss the main challenges and opportunities in the rapidly growing synthetic biology field and the important roles that chemical engineers can play in its advancement. PMID:24222925

  18. Challenges and opportunities in synthetic biology for chemical engineers

    SciTech Connect

    Luo, YZ; Lee, JK; Zhao, HM

    2013-11-15

    Synthetic biology provides numerous great opportunities for chemical engineers in the development of new processes for large-scale production of biofuels, value-added chemicals, and protein therapeutics. However, challenges across all scales abound. In particular, the modularization and standardization of the components in a biological system, so-called biological parts, remain the biggest obstacle in synthetic biology. In this perspective, we will discuss the main challenges and opportunities in the rapidly growing synthetic biology field and the important roles that chemical engineers can play in its advancement. (C) 2012 Elsevier Ltd. All rights reserved.

  19. High-End Computing Challenges in Aerospace Design and Engineering

    NASA Technical Reports Server (NTRS)

    Bailey, F. Ronald

    2004-01-01

    High-End Computing (HEC) has had significant impact on aerospace design and engineering and is poised to make even more in the future. In this paper we describe four aerospace design and engineering challenges: Digital Flight, Launch Simulation, Rocket Fuel System and Digital Astronaut. The paper discusses modeling capabilities needed for each challenge and presents projections of future near and far-term HEC computing requirements. NASA's HEC Project Columbia is described and programming strategies presented that are necessary to achieve high real performance.

  20. Dynamics of high-bypass-engine thrust reversal using a variable-pitch fan

    NASA Technical Reports Server (NTRS)

    Schaefer, J. W.; Sagerser, D. R.; Stakolich, E. G.

    1977-01-01

    The test program demonstrated that successful and rapid forward-to reverse-thrust transients can be performed without any significant engine operational limitations for fan blade pitch changes through either feather pitch or flat pitch. For through-feather-pitch operation with a flight inlet, fan stall problems were encountered, and a fan blade overshoot technique was used to establish reverse thrust.

  1. Challenges in translating vascular tissue engineering to the pediatric clinic.

    PubMed

    Duncan, Daniel R; Breuer, Christopher K

    2011-10-14

    The development of tissue-engineered vascular grafts for use in cardiovascular surgery holds great promise for improving outcomes in pediatric patients with complex congenital cardiac anomalies. Currently used synthetic grafts have a number of shortcomings in this setting but a tissue engineering approach has emerged in the past decade as a way to address these limitations. The first clinical trial of this technology showed that it is safe and effective but the primary mode of graft failure is stenosis. A variety of murine and large animal models have been developed to study and improve tissue engineering approaches with the hope of translating this technology into routine clinical use, but challenges remain. The purpose of this report is to address the clinical problem and review recent advances in vascular tissue engineering for pediatric applications. A deeper understanding of the mechanisms of neovessel formation and stenosis will enable rational design of improved tissue-engineered vascular grafts.

  2. Engineering Education and Students' Challenges: Strategies toward Enhancing the Educational Environment in Engineering Colleges

    ERIC Educational Resources Information Center

    Alkandari, Nabila Y.

    2014-01-01

    The main goal of this research is to gain an understanding of the challenges which have to be confronted by the engineering students at the College of Engineering and Petroleum at Kuwait University. The college has a large number of students, of which three hundred and eighty five were selected on a random basis for study purposes. The results…

  3. Engineering Education and Students' Challenges: Strategies toward Enhancing the Educational Environment in Engineering Colleges

    ERIC Educational Resources Information Center

    Alkandari, Nabila Y.

    2014-01-01

    The main goal of this research is to gain an understanding of the challenges which have to be confronted by the engineering students at the College of Engineering and Petroleum at Kuwait University. The college has a large number of students, of which three hundred and eighty five were selected on a random basis for study purposes. The results…

  4. The Teaching Challenge: Science, Engineering and the Knowledge Economy.

    ERIC Educational Resources Information Center

    Dowling, Patrick

    2001-01-01

    Presents the presidential address delivered to the Association for Science Education (ASE) at its annual meeting held at the University of Surrey, January 2001. Consists of three sections: (1) science and engineering and the knowledge economy; (2) teaching challenge and the role of science teachers; and (3) partnerships to support science,…

  5. Secondary Level Engineering Professional Development: Content, Pedagogy, and Challenges

    ERIC Educational Resources Information Center

    Daugherty, Jenny L.; Custer, Rodney L.

    2012-01-01

    The design of this study was a multiple case study conducted to examine the knowledge, pedagogical principles, and challenges involved in providing engineering-oriented professional development for teachers at the secondary school level. A set of criteria was used to identify five representative projects for analysis in the US. A variety of tools…

  6. Control Engineering, System Theory and Mathematics: The Teacher's Challenge

    ERIC Educational Resources Information Center

    Zenger, K.

    2007-01-01

    The principles, difficulties and challenges in control education are discussed and compared to the similar problems in the teaching of mathematics and systems science in general. The difficulties of today's students to appreciate the classical teaching of engineering disciplines, which are based on rigorous and scientifically sound grounds, are…

  7. A reverse transfection technology to genetically engineer adult stem cells.

    PubMed

    Okazaki, Arimichi; Jo, Jun-Ichiro; Tabata, Yasuhiko

    2007-02-01

    A new non-viral method of gene transfection was designed to enhance the level of gene expression for rat mesenchymal stem cells (MSCs). Pullulan was cationized using chemical introduction of spermine to prepare cationized pullulan of non-viral carrier (spermine-pullulan). The spermine-pullulan was complexed with a plasmid deoxyribonucleic acid (DNA) of luciferase and coated on the surface of culture substrate together with Pronectin of artificial cell adhesion protein. MSCs were cultured and transfected on the complex-coated substrate (reverse transfection), and the level and duration of gene expression were compared with those of MSCs transfected by culturing in the medium containing the plasmid DNA-spermine-pullulan complex (conventional method). The reverse transfection method enhanced and prolonged gene expression significantly more than did the conventional method. The reverse method permitted the transfection culture of MSCs in the presence of serum, in contrast to the conventional method, which gave cells a good culture condition to lower cytotoxicity. The reverse transfection was carried out for a non-woven fabric of polyethylene terephthalate (PET) coated with the complex and Pronectin using agitation and stirring culture methods. The two methods enhanced the level and duration of gene expression for MSCs significantly more than did the static method. It is possible that medium circulation improves the culture conditions of cells in terms of oxygen and nutrition supply and waste excretion, resulting in enhanced gene expression.

  8. Fiber-Based Tissue Engineering: Progress, Challenges, and Opportunities

    PubMed Central

    Tamayol, Ali; Akbari, Mohsen; Annabi, Nasim; Paul, Arghya; Khademhosseini, Ali; Juncker, David

    2013-01-01

    Tissue engineering aims to improve the function of diseased or damaged organs by creating biological substitutes. To fabricate a functional tissue, the engineered construct should mimic the physiological environment including its structural, topographical, and mechanical properties. Moreover, the construct should facilitate nutrients and oxygen diffusion as well as removal of metabolic waste during tissue regeneration. In the last decade, fiber-based techniques such as weaving, knitting, braiding, as well as electrospinning, and direct writing have emerged as promising platforms for making 3D tissue constructs that can address the above mentioned challenges. Here, we critically review the techniques used to form cell-free and cell-laden fibers and to assemble them into scaffolds. We compare their mechanical properties, morphological features and biological activity. We discuss current challenges and future opportunities of fiber-based tissue engineering (FBTE) for use in research and clinical practice. PMID:23195284

  9. Fiber-based tissue engineering: Progress, challenges, and opportunities.

    PubMed

    Tamayol, Ali; Akbari, Mohsen; Annabi, Nasim; Paul, Arghya; Khademhosseini, Ali; Juncker, David

    2013-01-01

    Tissue engineering aims to improve the function of diseased or damaged organs by creating biological substitutes. To fabricate a functional tissue, the engineered construct should mimic the physiological environment including its structural, topographical, and mechanical properties. Moreover, the construct should facilitate nutrients and oxygen diffusion as well as removal of metabolic waste during tissue regeneration. In the last decade, fiber-based techniques such as weaving, knitting, braiding, as well as electrospinning, and direct writing have emerged as promising platforms for making 3D tissue constructs that can address the abovementioned challenges. Here, we critically review the techniques used to form cell-free and cell-laden fibers and to assemble them into scaffolds. We compare their mechanical properties, morphological features and biological activity. We discuss current challenges and future opportunities of fiber-based tissue engineering (FBTE) for use in research and clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. The New Global Responsibilities of Engineers Create Challenges for Engineering Education

    ERIC Educational Resources Information Center

    Fuchs, Willi

    2012-01-01

    Modern societies aim to solve the global challenges of the 21st century with sustainable solutions such as resource efficiency, use of renewable energy sources and recycling. Engineers are called upon to create the cutting edge technological solutions that can help to address these challenges. In developed as well as in developing countries,…

  11. The New Global Responsibilities of Engineers Create Challenges for Engineering Education

    ERIC Educational Resources Information Center

    Fuchs, Willi

    2012-01-01

    Modern societies aim to solve the global challenges of the 21st century with sustainable solutions such as resource efficiency, use of renewable energy sources and recycling. Engineers are called upon to create the cutting edge technological solutions that can help to address these challenges. In developed as well as in developing countries,…

  12. Thrust-reverser flow investigation on a twin-engine transport

    NASA Technical Reports Server (NTRS)

    Gatlin, Gregory M.; Quinto, P. Frank

    1988-01-01

    An investigation was conducted in the NASA Langley 14 x 22 foot Subsonic Tunnel to study the effects of engine thrust reversing on an aft-mounted twin-engine transport and to develop effective testing techniques. Testing was done over a fixed and a moving-belt ground plane and over a pressure instrumented ground board. Free-stream dynamic pressure was set at values up to 12.2 psf, which corresponded to a maximum Reynolds number based on the mean aerodynamic chord of 765,000. The thrust reversers examined included cascade, target and four-door configurations. The investigation focused on the range of free-stream velocities and engine thrust-reverser flow rates that would be typical for landing ground-roll conditions. Flow visualization techniques were investigated, and the use of water or smoke injected into the reverser flow proved effective to determine the forward progression of the reversed flow and reingestion limits. When testing over a moving-belt ground plane, as opposed to a fixed ground plane, forward penetration of the reversed flow was reduced. The use of a pressure-instrumented ground board enabled reversed flow ground velocities to be obtained, and it provided a means by which to identify the reversed flow impingement point on the ground.

  13. Noise of model target type thrust reversers for engine-over-the-wing applications

    NASA Technical Reports Server (NTRS)

    Stone, J. R.; Gutierrez, O. A.

    1974-01-01

    The present work reports on experiments concerning the noise generated by V-gutter and semicylindrical target reversers with circular and short-aspect-ratio slot nozzles having equivalent diameters of about 5 cm. At subsonic jet velocities of interest for engine-over-the-wing (OTW) powered-lift aircraft, the reversers were noisier than the nozzles alone and had a more uniform directional distribution and more high-frequency noise. Reverser shape was more important than nozzle shape in determining the reverser noise characteristics. An estimate is made of perceived noise level along the 152-m sideline for a hypothetical OTW powered-lift airplane.

  14. Noise of model target type thrust reversers for engine-over-the-wing applications

    NASA Technical Reports Server (NTRS)

    Stone, J. R.; Gutierrez, O. A.

    1974-01-01

    The present work reports on experiments concerning the noise generated by V-gutter and semicylindrical target reversers with circular and short-aspect-ratio slot nozzles having equivalent diameters of about 5 cm. At subsonic jet velocities of interest for engine-over-the-wing (OTW) powered-lift aircraft, the reversers were noisier than the nozzles alone and had a more uniform directional distribution and more high-frequency noise. Reverser shape was more important than nozzle shape in determining the reverser noise characteristics. An estimate is made of perceived noise level along the 152-m sideline for a hypothetical OTW powered-lift airplane.

  15. Reverse engineering the embryo: a graduate course in developmental biology for engineering students at the University of Manitoba, Canada.

    PubMed

    Gordon, Richard; Melvin, Cameron A

    2003-01-01

    Our desire to educate engineers to be able to understand the component processes of embryogenesis, is driven by the notion that only when principles borrowed from mathematics, fluid mechanics, materials science, etc. are applied to classical problems in developmental biology, will sufficient comprehension be achieved to permit successful understanding and therapeutic manipulation of embryos. As it now stands, biologists seldom possess either skills or interest in those areas of endeavor. Thus, we have determined that it is easier to educate engineers in the principles of developmental biology than to help biologists deal with the complexities of engineering. We describe a graduate course that has been taken, between 1999 and 2002, by 17 engineering students. Our goal is to prepare them to reverse engineer the embryo, i.e., to look at it as an object or process whose construction, albeit self-construction, might be explicable in terms of engineering principles applied at molecular, cellular and whole embryo levels.

  16. A yeast synthetic network for in vivo assessment of reverse-engineering and modeling approaches.

    PubMed

    Cantone, Irene; Marucci, Lucia; Iorio, Francesco; Ricci, Maria Aurelia; Belcastro, Vincenzo; Bansal, Mukesh; Santini, Stefania; di Bernardo, Mario; di Bernardo, Diego; Cosma, Maria Pia

    2009-04-03

    Systems biology approaches are extensively used to model and reverse engineer gene regulatory networks from experimental data. Conversely, synthetic biology allows "de novo" construction of a regulatory network to seed new functions in the cell. At present, the usefulness and predictive ability of modeling and reverse engineering cannot be assessed and compared rigorously. We built in the yeast Saccharomyces cerevisiae a synthetic network, IRMA, for in vivo "benchmarking" of reverse-engineering and modeling approaches. The network is composed of five genes regulating each other through a variety of regulatory interactions; it is negligibly affected by endogenous genes, and it is responsive to small molecules. We measured time series and steady-state expression data after multiple perturbations. These data were used to assess state-of-the-art modeling and reverse-engineering techniques. A semiquantitative model was able to capture and predict the behavior of the network. Reverse engineering based on differential equations and Bayesian networks correctly inferred regulatory interactions from the experimental data.

  17. The reversal of diabetes in rat model using mouse insulin producing cells - a combination approach of tissue engineering and macroencapsulation.

    PubMed

    Muthyala, Sudhakar; Raj, V R Rana; Mohanty, Mira; Mohanan, P V; Nair, Prabha D

    2011-05-01

    Type 1 diabetes is a chronic disorder resulting from the autoimmune destruction of insulin-producing cells, a leading cause of morbidity and mortality all over the world. In this study a tissue engineering approach was compared with a macroencapsulation approach to reverse type 1 diabetes in a rat model, using mouse pancreatic progenitor cell (PPC)-derived islet-like clusters and mouse islets. For the tissue engineering approach the cells were cultured on gelatin scaffolds cross-linked with EDC in the presence of polyvinylpyrrolidone in vitro (GPE scaffolds), while for the macroencapsulation approach the cells were encapsulated in polyurethane-polyvinylpyrrolidone semi-interpenetrating networks. In the combination approach the cells cultured on GPE scaffolds were further encapsulated in a polyurethane-polyvinylpyrrolidone capsule. Real time PCR studies and the glucose challenge assay have shown that cells on GPE scaffolds could express and secrete insulin and glucagon in vitro. However, under in vivo conditions the animals treated by the tissue engineering approach died within 15-20 days and showed no reversal of their diabetes, due to infiltration of immune cells such as CD4 and CD8 cells and macrophages. In the macroencapsulation approach the animals showed euglycemia within 25 days, which was maintained for further 20 days, but after that the animals died. Interestingly, in the combination approach the animals showed reversal of hyperglycemia, and remained euglycemic for up to 3 months. The time needed to achieve initial euglycemia was different with different cell types, i.e. the combination approach with mouse islets achieved euglycemia within 15 days, whereas with PPC-derived islet-like clusters euglycemia was achieved within 25 days. This study confirmed that a combination of tissue engineering and macroencapsulation with mouse islets could reverse diabetes and maintain euglycemia in an experimental diabetes rat model for 90 days.

  18. 14 CFR 23.1155 - Turbine engine reverse thrust and propeller pitch settings below the flight regime.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Turbine engine reverse thrust and propeller... COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime. For turbine engine installations, each...

  19. 14 CFR 23.1155 - Turbine engine reverse thrust and propeller pitch settings below the flight regime.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Turbine engine reverse thrust and propeller... COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime. For turbine engine installations, each...

  20. 14 CFR 23.1155 - Turbine engine reverse thrust and propeller pitch settings below the flight regime.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Turbine engine reverse thrust and propeller... COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime. For turbine engine installations, each...

  1. 14 CFR 23.1155 - Turbine engine reverse thrust and propeller pitch settings below the flight regime.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Turbine engine reverse thrust and propeller... COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime. For turbine engine installations,...

  2. 14 CFR 23.1155 - Turbine engine reverse thrust and propeller pitch settings below the flight regime.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbine engine reverse thrust and propeller... COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime. For turbine engine installations,...

  3. Cell sheet engineering for regenerative medicine: current challenges and strategies.

    PubMed

    Owaki, Toshiyuki; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo

    2014-07-01

    Substantial progress made in the areas of stem cell research and regenerative medicine has provided a number of innovative methods to repair or regenerate defective tissues and organs. Although previous studies regarding regenerative medicine, especially those involving induced pluripotent stem cells, have been actively promoted in the past decade, there remain some challenges that need to be addressed in order to enable clinical applications. Designed for use in clinical applications, cell sheet engineering has been developed as a unique, scaffold-free method of cell processing utilizing temperature-responsive cell culture vessels. Clinical studies using cell sheets have shown positive outcomes and will be translated into clinical practice in the near future. However, several challenges stand in the way of the industrialization of cell sheet products and the widespread acceptance of regenerative medicine based on cell sheet engineering. This review describes current strategies geared towards the realization of the regenerative medicine approach.

  4. The 727 airplane target thrust reverser static performance model test for refanned JT8D engines

    NASA Technical Reports Server (NTRS)

    Chow, C. T. P.; Atkey, E. N.

    1974-01-01

    The results of a scale model static performance test of target thrust reverser configurations for the Pratt and Whitney Aircraft JT8D-100 series engine are presented. The objective of the test was to select a series of suitable candidate reverser configurations for the subsequent airplane model wind tunnel ingestion and flight controls tests. Test results indicate that adequate reverse thrust performance with compatible engine airflow match is achievable for the selected configurations. Tapering of the lips results in loss of performance and only minimal flow directivity. Door pressure surveys were conducted on a selected number of lip and fence configurations to obtain data to support the design of the thrust reverser system.

  5. Efforts and Challenges in Engineering the Genetic Code

    PubMed Central

    Lin, Xiao; Yu, Allen Chi Shing; Chan, Ting Fung

    2017-01-01

    This year marks the 48th anniversary of Francis Crick’s seminal work on the origin of the genetic code, in which he first proposed the “frozen accident” hypothesis to describe evolutionary selection against changes to the genetic code that cause devastating global proteome modification. However, numerous efforts have demonstrated the viability of both natural and artificial genetic code variations. Recent advances in genetic engineering allow the creation of synthetic organisms that incorporate noncanonical, or even unnatural, amino acids into the proteome. Currently, successful genetic code engineering is mainly achieved by creating orthogonal aminoacyl-tRNA/synthetase pairs to repurpose stop and rare codons or to induce quadruplet codons. In this review, we summarize the current progress in genetic code engineering and discuss the challenges, current understanding, and future perspectives regarding genetic code modification. PMID:28335420

  6. Efforts and Challenges in Engineering the Genetic Code.

    PubMed

    Lin, Xiao; Yu, Allen Chi Shing; Chan, Ting Fung

    2017-03-14

    This year marks the 48th anniversary of Francis Crick's seminal work on the origin of the genetic code, in which he first proposed the "frozen accident" hypothesis to describe evolutionary selection against changes to the genetic code that cause devastating global proteome modification. However, numerous efforts have demonstrated the viability of both natural and artificial genetic code variations. Recent advances in genetic engineering allow the creation of synthetic organisms that incorporate noncanonical, or even unnatural, amino acids into the proteome. Currently, successful genetic code engineering is mainly achieved by creating orthogonal aminoacyl-tRNA/synthetase pairs to repurpose stop and rare codons or to induce quadruplet codons. In this review, we summarize the current progress in genetic code engineering and discuss the challenges, current understanding, and future perspectives regarding genetic code modification.

  7. Tissue engineering of heart valves: advances and current challenges.

    PubMed

    Mol, Anita; Smits, Anthal I P M; Bouten, Carlijn V C; Baaijens, Frank P T

    2009-05-01

    It is estimated that the number of patients requiring heart valve replacement will triple over the next five decades. None of the current replacement valves can fully restore native valve function because they lack growth and remodeling capabilities. Heart valve tissue engineering is a promising technology to overcome these limitations. Various approaches are being employed, either aimed at development of the valve substitute in vitro or at the use of the regenerative potential of the body (in situ) for the tissue culture phase. This review provides an overview of the progress within both the in vitro and in situ tissue engineering approaches for trileaflet heart valve tissue engineering. Current challenges with these approaches are discussed, focusing in particular on the use of synthetic scaffold materials.

  8. Reverse Flow Engine Core Having a Ducted Fan with Integrated Secondary Flow Blades

    NASA Technical Reports Server (NTRS)

    Kisska, Michael K. (Inventor); Princen, Norman H. (Inventor); Kuehn, Mark S. (Inventor); Cosentino, Gary B. (Inventor)

    2014-01-01

    Secondary air flow is provided for a ducted fan having a reverse flow turbine engine core driving a fan blisk. The fan blisk incorporates a set of thrust fan blades extending from an outer hub and a set of integral secondary flow blades extending intermediate an inner hub and the outer hub. A nacelle provides an outer flow duct for the thrust fan blades and a secondary flow duct carries flow from the integral secondary flow blades as cooling air for components of the reverse flow turbine engine.

  9. Challenges in engineering osteochondral tissue grafts with hierarchical structures.

    PubMed

    Gadjanski, Ivana; Vunjak-Novakovic, Gordana

    2015-01-01

    A major hurdle in treating osteochondral (OC) defects is the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens and harnessing of inflammatory responses of the host will likely drive the further progress.

  10. Reverse quantum state engineering using electronic feedback loops

    NASA Astrophysics Data System (ADS)

    Kießlich, Gerold; Emary, Clive; Schaller, Gernot; Brandes, Tobias

    2012-12-01

    We propose an all-electronic technique to manipulate and control interacting quantum systems by unitary single-jump feedback conditioned on the outcome of a capacitively coupled electrometer and, in particular, a single-electron transistor. We provide a general scheme for stabilizing pure states in the quantum system and use an effective Hamiltonian method for the quantum master equation to elaborate on the nature of stabilizable states and the conditions under which state purification can be achieved. The state engineering within the quantum feedback scheme is shown to be linked with the solution of an inverse eigenvalue problem. Two applications of the feedback scheme are presented in detail: (i) stabilization of delocalized pure states in a single charge qubit and (ii) entanglement stabilization in two coupled charge qubits. In the latter example, we demonstrate the stabilization of a maximally entangled Bell state for certain detector positions and local feedback operations.

  11. Reversed Janus Micro/Nanomotors with Internal Chemical Engine

    PubMed Central

    2016-01-01

    Self-motile Janus colloids are important for enabling a wide variety of microtechnology applications as well as for improving our understanding of the mechanisms of motion of artificial micro- and nanoswimmers. We present here micro/nanomotors which possess a reversed Janus structure of an internal catalytic “chemical engine”. The catalytic material (here platinum (Pt)) is embedded within the interior of the mesoporous silica (mSiO2)-based hollow particles and triggers the decomposition of H2O2 when suspended in an aqueous peroxide (H2O2) solution. The pores/gaps at the noncatalytic (Pt) hemisphere allow the exchange of chemical species in solution between the exterior and the interior of the particle. By varying the diameter of the particles, we observed size-dependent motile behavior in the form of enhanced diffusion for 500 nm particles, and self-phoretic motion, toward the nonmetallic part, for 1.5 and 3 μm ones. The direction of motion was rationalized by a theoretical model based on self-phoresis. For the 3 μm particles, a change in the morphology of the porous part is observed, which is accompanied by a change in the mechanism of propulsion via bubble nucleation and ejection as well as a change in the direction of motion. PMID:27598543

  12. Compact Reversed-Field Pinch Reactors (CRFPR): preliminary engineering considerations

    SciTech Connect

    Hagenson, R.L.; Krakowski, R.A.; Bathke, C.G.; Miller, R.L.; Embrechts, M.J.; Schnurr, N.M.; Battat, M.E.; LaBauve, R.J.; Davidson, J.W.

    1984-08-01

    The unique confinement physics of the Reversed-Field Pinch (RFP) projects to a compact, high-power-density fusion reactor that promises a significant reduction in the cost of electricity. The compact reactor also promises a factor-of-two reduction in the fraction of total cost devoted to the reactor plant equipment (i.e., fusion power core (FPC) plus support systems). In addition to operational and developmental benefits, these physically smaller systems can operate economically over a range of total power output. After giving an extended background and rationale for the compact fusion approaches, key FPC subsystems for the Compact RFP Reactor (CRFPR) are developed, designed, and integrated for a minimum-cost, 1000-MWe(net) system. Both the problems and promise of the compact, high-power-density fusion reactor are quantitatively evaluated on the basis of this conceptual design. The material presented in this report both forms a framework for a broader, more expanded conceptual design as well as suggests directions and emphases for related research and development.

  13. Liver tissue engineering and cell sources: issues and challenges.

    PubMed

    Palakkan, Anwar A; Hay, David C; Anil Kumar, P R; Kumary, T V; Ross, James A

    2013-05-01

    Liver diseases are of major concern as they now account for millions of deaths annually. As a result of the increased incidence of liver disease, many patients die on the transplant waiting list, before a donor organ becomes available. To meet the huge demand for donor liver, alternative approaches using liver tissue engineering principles are being actively pursued. Even though adult hepatocytes, the primary cells of the liver are most preferred for tissue engineering of liver, their limited availability, isolation from diseased organs, lack of in vitro propagation and deterioration of function acts as a major drawback to their use. Various approaches have been taken to prevent the functional deterioration of hepatocytes including the provision of an adequate extracellular matrix and co-culture with non-parenchymal cells of liver. Great progress has also been made to differentiate human stem cells to hepatocytes and to use them for liver tissue engineering applications. This review provides an overview of recent challenges, issues and cell sources with regard to liver tissue engineering.

  14. Chemical engineering challenges and investment opportunities in sustainable energy.

    PubMed

    Heller, Adam

    2008-01-01

    The chemical and energy industries are transforming as they adjust to the new era of high-priced petroleum and severe global warming. As a result of the transformation, engineering challenges and investment opportunities abound. Rapid evolution and fast growth are expected in cathode and anode materials as well as polymeric electrolytes for vehicular batteries and in high-performance polymer-ceramic composites for wind turbines, fuel-efficient aircraft, and lighter and safer cars. Unique process-engineering opportunities exist in sand-oil, coal, and possibly also shale liquefaction to produce transportation fuel; and also in genetic engineering of photosynthesizing plants and other organisms for their processing into high-performance biodegradable polymers and high-value-added environmentally friendly chemicals. Also, research on the feasibility of mitigation of global warming through enhancement of CO(2) uptake by the southern oceans by fertilization with trace amounts of iron is progressing. Because chemical engineers are uniquely well trained in mathematical modeling of mass transport, flow, and mixing, and also in cost analysis, they are likely to join the oceanographers and marine biologists in this important endeavor.

  15. Challenges and Perspectives in Nucleic Acid Enzyme Engineering.

    PubMed

    Balke, Darko; Hieronymus, Robert; Müller, Sabine

    2017-08-04

    Engineering of nucleic acids has been a goal in research for many years. Since the discovery of catalytic nucleic acids (ribozymes and DNAzymes), this field has attracted even more attention. One reason for the increased interest is that a large number of ribozymes have been engineered that catalyze a broad range of reactions of relevance to the origin of life. Another reason is that the structures of ribozymes or DNAzymes have been modulated such that activity is dependent on allosteric regulation by an external cofactor. Such constructs have great potential for application as biosensors in medicinal or environmental diagnostics, and as molecular tools for control of cellular processes. In addition to the development of nucleic acid enzymes by in vitro selection, rational design is a powerful strategy for the engineering of ribozymes or DNAzymes with tailored features. The structures and mechanisms of a large number of nucleic acid catalysts are now well understood. Therefore, specific design of their functional properties by structural modulation is a good option for the development of custom-made molecular tools. For rational design, several parameters have to be considered, and a number of tools are available to help/guide sequence design. Here, we discuss sequence, structural and functional design using the example of hairpin ribozyme variants to highlight the challenges and opportunities of rational nucleic enzyme engineering. Graphical Abstract.

  16. Rapid prototyping in tissue engineering: challenges and potential.

    PubMed

    Yeong, Wai-Yee; Chua, Chee-Kai; Leong, Kah-Fai; Chandrasekaran, Margam

    2004-12-01

    Tissue engineering aims to produce patient-specific biological substitutes in an attempt to circumvent the limitations of existing clinical treatments for damaged tissue or organs. The main regenerative tissue engineering approach involves transplantation of cells onto scaffolds. The scaffold attempts to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. Scaffolds should have suitable architecture and strength to serve their intended function. This paper presents a comprehensive review of the fabrication methods, including conventional, mainly manual, techniques and advanced processing methods such as rapid prototyping (RP) techniques. The potential and challenges of scaffold-based technology are discussed from the perspective of RP technology.

  17. Bioreactors in Tissue Engineering: Scientific Challenges and Clinical Perspectives

    NASA Astrophysics Data System (ADS)

    Wendt, D.; Riboldi, S. A.; Cioffi, M.; Martin, I.

    In this Chapter we discuss the role of bioreactors in the translational paradigm of Tissue Engineering approaches from basic research to streamlined tissue manufacturing. In particular, we will highlight their functions as: (1) Pragmatic tools for tissue engineers, making up for limitations of conventional manual and static techniques, enabling automation and allowing physical conditioning of the developing tissues; (2) 3D culture model systems, enabling us to recapitulate specific aspects of the actual in vivo milieu and, when properly integrated with computational modeling efforts and sensing and control techniques, to address challenging scientific questions; (3) Tissue manufacturing devices, implementing bioprocesses so as to support safe, standardized, scaleable, traceable and possibly cost-effective production of grafts for clinical use. We will provide evidences that fundamental knowledge gained through the use of well-defined and controlled bio-reactor systems at the research level will be essential to define, optimize, and moreover, streamline the key processes required for efficient manufacturing models.

  18. Development of mobile, on-site engine coolant recycling utilizing reverse-osmosis technology

    SciTech Connect

    Kughn, W.; Eaton, E.R.

    1999-08-01

    This paper presents the history of the development of self-contained, mobile, high-volume, engine coolant recycling by reverse osmosis (R/O). It explains the motivations, created by government regulatory agencies, to minimize the liability of waste generators who produce waste engine coolant by providing an engine coolant recycling service at the customer`s location. Recycling the used engine coolant at the point of origin minimizes the generators` exposure to documentation requirements, liability, and financial burdens by greatly reducing the volume of used coolant that must be hauled from the generator`s property. It describes the inherent difficulties of recycling such a highly contaminated, inconsistent input stream, such as used engine coolant, by reverse osmosis. The paper reports how the difficulties were addressed, and documents the state of the art in mobile R/O technology. Reverse osmosis provides a purified intermediate fluid that is reinhibited for use in automotive cooling systems. The paper offers a review of experiences in various automotive applications, including light-duty, medium-duty and heavy-duty vehicles operating on many types of fuel. The authors conclude that mobile embodiments of R/O coolant recycling technology provide finished coolants that perform equivalently to new coolants as demonstrated by their ability to protect vehicles from freezing, corrosion damage, and other cooling system related problems.

  19. System Engineering and Technical Challenges Overcome in the J-2X Rocket Engine Development Project

    NASA Technical Reports Server (NTRS)

    Ballard, Richard O.

    2012-01-01

    Beginning in 2006, NASA initiated the J-2X engine development effort to develop an upper stage propulsion system to enable the achievement of the primary objectives of the Constellation program (CxP): provide continued access to the International Space Station following the retirement of the Space Station and return humans to the moon. The J-2X system requirements identified to accomplish this were very challenging and the time expended over the five years following the beginning of the J- 2X effort have been noteworthy in the development of innovations in both the fields for liquid rocket propulsion and system engineering.

  20. Tissue engineering interventions for esophageal disorders--promises and challenges.

    PubMed

    Kuppan, Purushothaman; Sethuraman, Swaminathan; Krishnan, Uma Maheswari

    2012-01-01

    The diseases of the esophagus include congenital defects like atresia, tracheoesophageal fistula as well as others such as gastro-esophageal reflux disease (GERD), Barrett's esophagus, carcinoma and strictures. All esophageal disorders require surgical intervention and reconstruction with appropriate substitutes. Primary anastomosis is used to treat most cases but treatment of long gap atresia still remains a clinical challenge. Autologous graft therapies using tissues from colon, and small and large intestine or gastric transplantations have been attempted but have constraints like leakage, infection and stenosis at the implanted site, which leads to severe morbidity and mortality. An alternative for autologous grafts are allogenic and xenogenic grafts, which have better availability but disease transmission and immunogenicity limit their applications. Use of biodegradable and biocompatible scaffolds to engineer the esophagus promises to be an effective regenerative strategy for treatment of esophageal disorders. Nanotopography of the fibrous scaffolds mimics the natural extracellular matrix (ECM) of the tissue and incorporation of chemical cues and tailoring mechanical properties provide the right microenvironment for co-culture of different cell types. Scaffolds cultured with esophageal cells (epithelial cells, fibroblast and smooth muscle cells) might show enhancement of the biofunctionality in vivo. This review attempts to address the various strategies and challenges involved in successful tissue engineering of the esophagus. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. The Challenge of Centennial Earthquakes to Improve Modern Earthquake Engineering

    SciTech Connect

    Saragoni, G. Rodolfo

    2008-07-08

    The recent commemoration of the centennial of the San Francisco and Valparaiso 1906 earthquakes has given the opportunity to reanalyze their damages from modern earthquake engineering perspective. These two earthquakes plus Messina Reggio Calabria 1908 had a strong impact in the birth and developing of earthquake engineering. The study of the seismic performance of some up today existing buildings, that survive centennial earthquakes, represent a challenge to better understand the limitations of our in use earthquake design methods. Only Valparaiso 1906 earthquake, of the three considered centennial earthquakes, has been repeated again as the Central Chile, 1985, Ms = 7.8 earthquake. In this paper a comparative study of the damage produced by 1906 and 1985 Valparaiso earthquakes is done in the neighborhood of Valparaiso harbor. In this study the only three centennial buildings of 3 stories that survived both earthquakes almost undamaged were identified. Since for 1985 earthquake accelerogram at El Almendral soil conditions as well as in rock were recoded, the vulnerability analysis of these building is done considering instrumental measurements of the demand. The study concludes that good performance of these buildings in the epicentral zone of large earthquakes can not be well explained by modern earthquake engineering methods. Therefore, it is recommended to use in the future of more suitable instrumental parameters, such as the destructiveness potential factor, to describe earthquake demand.

  2. Novel opportunities and challenges offered by nanobiomaterials in tissue engineering

    PubMed Central

    Gelain, Fabrizio

    2008-01-01

    Over the last decades, tissue engineering has demonstrated an unquestionable potential to regenerate damaged tissues and organs. Some tissue-engineered solutions recently entered the clinics (eg, artificial bladder, corneal epithelium, engineered skin), but most of the pathologies of interest are still far from being solved. The advent of stem cells opened the door to large-scale production of “raw living matter” for cell replacement and boosted the overall sector in the last decade. Still reliable synthetic scaffolds fairly resembling the nanostructure of extracellular matrices, showing mechanical properties comparable to those of the tissues to be regenerated and capable of being modularly functionalized with biological active motifs, became feasible only in the last years thanks to newly introduced nanotechnology techniques of material design, synthesis, and characterization. Nanostructured synthetic matrices look to be the next generation scaffolds, opening new powerful pathways for tissue regeneration and introducing new challenges at the same time. We here present a detailed overview of the advantages, applications, and limitations of nanostructured matrices with a focus on both electrospun and self-assembling scaffolds. PMID:19337410

  3. Perfect quantum state engineering by the combination of the counterdiabatic driving and the reverse-engineering technique

    NASA Astrophysics Data System (ADS)

    Wu, Qi-Cheng; Huang, Bi-Hua; Chen, Ye-Hong; Shi, Zhi-Cheng; Song, Jie; Xia, Yan

    2017-10-01

    We propose a method to design shortcuts to adiabaticity for implementing perfect quantum state engineering by the combination of the counterdiabatic driving and the reverse engineering technique. Based on the method, we can design simple schemes to realize the intended dynamics. For the sake of clearness, we apply this method to several examples including two-level, three-level and four-level system. We show that fast quantum state engineering can be realized by utilizing simply-designed auxiliary Hamiltonian. Furthermore, a suitable choice of the control parameters can eliminate the additional couplings in the introduced auxiliary Hamiltonian. Numerical simulation reveals that the constructed scheme is reliable and robust against various dissipation effects and the fluctuations of control parameters in current technology.

  4. Navier-Stokes analysis of a very-high-bypass-ratio turbofan engine in reverse thrust

    NASA Astrophysics Data System (ADS)

    Brown, Jeffrey J.

    1987-06-01

    An algorithm based upon MacCormack's implicit line Gauss-Seidel Navier-Stokes scheme has been modified to model the flowfield in very-high-bypass-ratio turbofan engines under reverse-thrust conditions. It is assumed that reverse thrust is to be achieved through fan blade pitch changes. The physics at the fan blade is modeled using an actuator disk to simulate the fan pumping characteristics. The algorithm, including boundary conditions, is described, and three different flowfields are presented as illustrations of possible results.

  5. Bayesian approaches to reverse engineer cellular systems: a simulation study on nonlinear Gaussian networks.

    PubMed

    Ferrazzi, Fulvia; Sebastiani, Paola; Ramoni, Marco F; Bellazzi, Riccardo

    2007-05-24

    Reverse engineering cellular networks is currently one of the most challenging problems in systems biology. Dynamic Bayesian networks (DBNs) seem to be particularly suitable for inferring relationships between cellular variables from the analysis of time series measurements of mRNA or protein concentrations. As evaluating inference results on a real dataset is controversial, the use of simulated data has been proposed. However, DBN approaches that use continuous variables, thus avoiding the information loss associated with discretization, have not yet been extensively assessed, and most of the proposed approaches have dealt with linear Gaussian models. We propose a generalization of dynamic Gaussian networks to accommodate nonlinear dependencies between variables. As a benchmark dataset to test the new approach, we used data from a mathematical model of cell cycle control in budding yeast that realistically reproduces the complexity of a cellular system. We evaluated the ability of the networks to describe the dynamics of cellular systems and their precision in reconstructing the true underlying causal relationships between variables. We also tested the robustness of the results by analyzing the effect of noise on the data, and the impact of a different sampling time. The results confirmed that DBNs with Gaussian models can be effectively exploited for a first level analysis of data from complex cellular systems. The inferred models are parsimonious and have a satisfying goodness of fit. Furthermore, the networks not only offer a phenomenological description of the dynamics of cellular systems, but are also able to suggest hypotheses concerning the causal interactions between variables. The proposed nonlinear generalization of Gaussian models yielded models characterized by a slightly lower goodness of fit than the linear model, but a better ability to recover the true underlying connections between variables.

  6. [Reversible cerebral vasoconstriction syndrome. Challenge for diagnostics and intensive care therapy].

    PubMed

    Jansen, G; Mertzlufft, F; Bach, F

    2015-08-01

    Reversible cerebral vasoconstriction syndrome (RCVS) is a disease of unclear incidence frequently affecting middle aged women and is usually associated with use of adrenergic or serotoninergic substances. The exclusion of relevant differential diagnoses, such as aneurysmal subarachnoid hemorrhage, primary cerebral angiitis, posterior reversible encephalopathy syndrome and carotid artery dissection is critical in terms of time and significance. Thunderclap headache as well as multiple and multilocular vasospasms with direct or indirect angiography without substantial findings in cerebrospinal fluid diagnostics are typical symptoms. The necessity for intensive care treatment is often justified by initial acute impairment of vital functions and possible development of cerebral or extracerebral complications. Because the exact pathophysiology remains unknown, a specific therapy does not exist. This poses significant challenges in intensive care medicine, which are illustrated on the basis of the case study presented.

  7. Reversals.

    ERIC Educational Resources Information Center

    National Center on Educational Media and Materials for the Handicapped, Columbus, OH.

    Selected from the National Instructional Materials Information System (NIMIS)--a computer based on-line interactive retrieval system on special education materials--the bibliography covers nine materials for remediating reversals in handicapped students at the early childhood and elementary levels. Entries are presented in order of NIMIS accession…

  8. Effect of forward velocity and crosswind on the reverse-thrust performance of a variable-pitch fan engine

    NASA Technical Reports Server (NTRS)

    Reemsnyder, D. C.; Sagerser, D. A.

    1979-01-01

    A full-size variable-pitch fan engine was tested in the Ames 40 by 80 foot wind tunnel to determine the effect of forward velocity and crosswind on reverse-thrust performance. Two flight-type inlet configurations were tested, and a flared fan nozzle was installed as an inlet for reverse-thrust operation. Steady-state reverse-thrust performance was obtained up to 54 m/s (105 knots). An abrupt decrease in reverse thrust occurred at about 30 m/s (60 knots). Reverse thrust was established following forward-to-reverse thrust transients both statically and with forward velocities only up to 30 m/s.

  9. Advanced dimensional inspection for the reverse engineering of power plant equipment

    SciTech Connect

    Kotteakos, B.; Ball, K.A.

    1996-12-31

    Forced outages and critical path situations often leave electric utilities with very few options other than the OEM. What does the utility do when faced with the situation of long lead time or obsolete items necessary to bring units back on-line, or off load restrictions. At Southern California Edison Company (SCE), a proactive approach to the reverse engineering and inspection process was undertaken to reduce the effects of similar situations. Advances in dimensional measurement technology have afforded the authors` company a cost effective method for obtaining the necessary inspection data to remanufacture certain items. This paper identifies equipment utilized by SCE for the reverse engineering and inspection of turbine and turbine related components and their typical applications in the power generation industry.

  10. A Survey of Statistical Models for Reverse Engineering Gene Regulatory Networks

    PubMed Central

    Huang, Yufei; Tienda-Luna, Isabel M.; Wang, Yufeng

    2009-01-01

    Statistical models for reverse engineering gene regulatory networks are surveyed in this article. To provide readers with a system-level view of the modeling issues in this research, a graphical modeling framework is proposed. This framework serves as the scaffolding on which the review of different models can be systematically assembled. Based on the framework, we review many existing models for many aspects of gene regulation; the pros and cons of each model are discussed. In addition, network inference algorithms are also surveyed under the graphical modeling framework by the categories of point solutions and probabilistic solutions and the connections and differences among the algorithms are provided. This survey has the potential to elucidate the development and future of reverse engineering GRNs and bring statistical signal processing closer to the core of this research. PMID:20046885

  11. Reverse engineering of a nonlossy adiabatic Hamiltonian for non-Hermitian systems

    NASA Astrophysics Data System (ADS)

    Wu, Qi-Cheng; Chen, Ye-Hong; Huang, Bi-Hua; Xia, Yan; Song, Jie

    2016-11-01

    We generalize the quantum adiabatic theorem to the non-Hermitian system and build a strict adiabaticity condition to make the adiabatic evolution nonlossy when taking into account the effect of the adiabatic phase. According to the strict adiabaticity condition, the nonadiabatic couplings and the effect of the imaginary part of adiabatic phase should be eliminated as much as possible. Also, the non-Hermitian Hamiltonian reverse-engineering method is proposed for adiabatically driving an artificial quantum state. A concrete two-level system is adopted to show the usefulness of the reverse-engineering method. We obtain the desired target state by adjusting extra rotating magnetic fields at a predefined time. Furthermore, the numerical simulation shows that certain noise and dissipation in the systems are no longer undesirable but play a positive role in the scheme. Therefore, the scheme is quite useful for quantum information processing in some dissipative systems.

  12. Spatiotemporal control of cell-cell reversible interactions using molecular engineering

    NASA Astrophysics Data System (ADS)

    Shi, Peng; Ju, Enguo; Yan, Zhengqing; Gao, Nan; Wang, Jiasi; Hou, Jianwen; Zhang, Yan; Ren, Jinsong; Qu, Xiaogang

    2016-10-01

    Manipulation of cell-cell interactions has potential applications in basic research and cell-based therapy. Herein, using a combination of metabolic glycan labelling and bio-orthogonal click reaction, we engineer cell membranes with β-cyclodextrin and subsequently manipulate cell behaviours via photo-responsive host-guest recognition. With this methodology, we demonstrate reversible manipulation of cell assembly and disassembly. The method enables light-controllable reversible assembly of cell-cell adhesion, in contrast with previously reported irreversible effects, in which altered structure could not be reused. We also illustrate the utility of the method by designing a cell-based therapy. Peripheral blood mononuclear cells modified with aptamer are effectively redirected towards target cells, resulting in enhanced cell apoptosis. Our approach allows precise control of reversible cell-cell interactions and we expect that it will promote further developments of cell-based therapy.

  13. Noise of model target type thrust reversers for engine-over-the-wing applications

    NASA Technical Reports Server (NTRS)

    Stone, J. R.; Gutierrez, O. A.

    1974-01-01

    The results of experiments on the noise generated by V-gutter and semicylindrical target reversers with circular and short-aspect-ratio slot nozzles having diameters of about 5 cm are presented. The experiments were conducted with cold-flow jets at velocities from 190-290 m/sec. The reversers at subsonic jet velocities had a more uniform noise distribution and higher frequency than the nozzles alone. The reverser shape was shown to be more important than the nozzle shape in determining the noise characteristics. The maximum sideline pressure level varied with the sixth power of the jet velocity, and the data were correlated for angles along the sideline. An estimate of the noise level along the 152 m sideline for an engine-over-the-wing powered-lift airplane was made.

  14. Spatiotemporal control of cell–cell reversible interactions using molecular engineering

    PubMed Central

    Shi, Peng; Ju, Enguo; Yan, Zhengqing; Gao, Nan; Wang, Jiasi; Hou, Jianwen; Zhang, Yan; Ren, Jinsong; Qu, Xiaogang

    2016-01-01

    Manipulation of cell–cell interactions has potential applications in basic research and cell-based therapy. Herein, using a combination of metabolic glycan labelling and bio-orthogonal click reaction, we engineer cell membranes with β-cyclodextrin and subsequently manipulate cell behaviours via photo-responsive host-guest recognition. With this methodology, we demonstrate reversible manipulation of cell assembly and disassembly. The method enables light-controllable reversible assembly of cell–cell adhesion, in contrast with previously reported irreversible effects, in which altered structure could not be reused. We also illustrate the utility of the method by designing a cell-based therapy. Peripheral blood mononuclear cells modified with aptamer are effectively redirected towards target cells, resulting in enhanced cell apoptosis. Our approach allows precise control of reversible cell–cell interactions and we expect that it will promote further developments of cell-based therapy. PMID:27708265

  15. DEFINING THE PLAYERS IN HIGHER-ORDER NETWORKS: PREDICTIVE MODELING FOR REVERSE ENGINEERING FUNCTIONAL INFLUENCE NETWORKS

    SciTech Connect

    McDermott, Jason E.; Costa, Michelle N.; Stevens, S.L.; Stenzel-Poore, Mary; Sanfilippo, Antonio P.

    2011-01-20

    A difficult problem that is currently growing rapidly due to the sharp increase in the amount of high-throughput data available for many systems is that of determining useful and informative causative influence networks. These networks can be used to predict behavior given observation of a small number of components, predict behavior at a future time point, or identify components that are critical to the functioning of the system under particular conditions. In these endeavors incorporating observations of systems from a wide variety of viewpoints can be particularly beneficial, but has often been undertaken with the objective of inferring networks that are generally applicable. The focus of the current work is to integrate both general observations and measurements taken for a particular pathology, that of ischemic stroke, to provide improved ability to produce useful predictions of systems behavior. A number of hybrid approaches have recently been proposed for network generation in which the Gene Ontology is used to filter or enrich network links inferred from gene expression data through reverse engineering methods. These approaches have been shown to improve the biological plausibility of the inferred relationships determined, but still treat knowledge-based and machine-learning inferences as incommensurable inputs. In this paper, we explore how further improvements may be achieved through a full integration of network inference insights achieved through application of the Gene Ontology and reverse engineering methods with specific reference to the construction of dynamic models of transcriptional regulatory networks. We show that integrating two approaches to network construction, one based on reverse-engineering from conditional transcriptional data, one based on reverse-engineering from in situ hybridization data, and another based on functional associations derived from Gene Ontology, using probabilities can improve results of clustering as evaluated by a

  16. Using a Formal Approach for Reverse Engineering and Design Recovery to Support Software Reuse

    NASA Technical Reports Server (NTRS)

    Gannod, Gerald C.

    2002-01-01

    This document describes 3rd year accomplishments and summarizes overall project accomplishments. Included as attachments are all published papers from year three. Note that the budget for this project was discontinued after year two, but that a residual budget from year two allowed minimal continuance into year three. Accomplishments include initial investigations into log-file based reverse engineering, service-based software reuse, and a source to XML generator.

  17. CMS-2 Reverse Engineering and ENCORE/SRE Integration, Revised Final Report

    DTIC Science & Technology

    1992-07-01

    approved for piblic release and sale; its disttibution is unlimited. 92- 18302 92 Table of Contents CMS -2 Reverse Engineering and ENCORE/SRE Integration...contract demonstrates that: e Automated extraction of design information from an existing software system written in CMS -2 can be used to document that...1992 1 The key features of the CMS RET system are: 9 The interactive visual interface to the extracted information is provided by a commer- cially

  18. A proposal for reverse engineering CASE tools to support new software development

    SciTech Connect

    Maxted, A.

    1993-06-01

    Current CASE technology provides sophisticated diagramming tools to generate a software design. The design, stored internal to the CASE tool, is bridged to the code via code generators. There are several limitations to this technique: (1) the portability of the design is limited to the portability of the CASE tools, and (2) the code generators offer a clumsy link between design and code. The CASE tool though valuable during design, becomes a hindrance during implementation. Frustration frequently causes the CASE tool to be abandoned during implementation, permanently severing the link between design and code. Current CASE stores the design in a CASE internal structure, from which code is generated. The technique presented herein suggests that CASE tools store the system knowledge directly in code. The CASE support then switches from an emphasis on code generators to employing state-of-the-art reverse engineering techniques for document generation. Graphical and textual descriptions of each software component (e.g., Ada Package) may be generated via reverse engineering techniques from the code. These reverse engineered descriptions can be merged with system over-view diagrams to form a top-level design document. The resulting document can readily reflect changes to the software components by automatically generating new component descriptions for the changed components. The proposed auto documentation technique facilitates the document upgrade task at later stages of development, (e.g., design, implementation and delivery) by using the component code as the source of the component descriptions. The CASE technique presented herein is a unique application of reverse engineering techniques to new software systems. This technique contrasts with more traditional CASE auto code generation techniques.

  19. Engineering of obligate intracellular bacteria: progress, challenges and paradigms.

    PubMed

    McClure, Erin E; Chávez, Adela S Oliva; Shaw, Dana K; Carlyon, Jason A; Ganta, Roman R; Noh, Susan M; Wood, David O; Bavoil, Patrik M; Brayton, Kelly A; Martinez, Juan J; McBride, Jere W; Valdivia, Raphael H; Munderloh, Ulrike G; Pedra, Joao H F

    2017-09-01

    It is estimated that approximately one billion people are at risk of infection with obligate intracellular bacteria, but little is known about the underlying mechanisms that govern their life cycles. The difficulty in studying Chlamydia spp., Coxiella spp., Rickettsia spp., Anaplasma spp., Ehrlichia spp. and Orientia spp. is, in part, due to their genetic intractability. Recently, genetic tools have been developed; however, optimizing the genomic manipulation of obligate intracellular bacteria remains challenging. In this Review, we describe the progress in, as well as the constraints that hinder, the systematic development of a genetic toolbox for obligate intracellular bacteria. We highlight how the use of genetically manipulated pathogens has facilitated a better understanding of microbial pathogenesis and immunity, and how the engineering of obligate intracellular bacteria could enable the discovery of novel signalling circuits in host-pathogen interactions.

  20. Quantifying and imaging engineered nanomaterials in vivo: challenges and techniques.

    PubMed

    He, Xiao; Ma, Yuhui; Li, Meng; Zhang, Peng; Li, Yuanyuan; Zhang, Zhiyong

    2013-05-27

    Quantifying and imaging the engineered nanomaterials (ENMs) in vivo can provide information on the bio-distribution and fate of ENMs in living systems. A necessary amount of in vivo quantitative data is indispensable to verify the extrapolation from in vitro tests, to modify the predictive models of ENM exposure, and to underpin the risk management strategy for ENMs. However, it remains a challenge to quantitatively assess the bio-distribution of ENMs under realistic exposure, their long-term deposition (especially in non-targeted tissues), their passage across the natural barriers, and the impacts of nano-bio interactions on their in vivo behaviors. Some commonly used techniques for in vivo ENM quantification, such as electron microscopy, fluorescence-based detection, atomic spectroscopy, radiotracing, and techniques basing on synchrotron radiation are reviewed, and their technical characteristics, the state of the art, limitations, and future prospects are addressed.

  1. Rapid prototyping for biomedical engineering: current capabilities and challenges.

    PubMed

    Lantada, Andrés Díaz; Morgado, Pilar Lafont

    2012-01-01

    A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends.

  2. Reverse engineering biological networks :applications in immune responses to bio-toxins.

    SciTech Connect

    Martino, Anthony A.; Sinclair, Michael B.; Davidson, George S.; Haaland, David Michael; Timlin, Jerilyn Ann; Thomas, Edward Victor; Slepoy, Alexander; Zhang, Zhaoduo; May, Elebeoba Eni; Martin, Shawn Bryan; Faulon, Jean-Loup Michel

    2005-12-01

    Our aim is to determine the network of events, or the regulatory network, that defines an immune response to a bio-toxin. As a model system, we are studying T cell regulatory network triggered through tyrosine kinase receptor activation using a combination of pathway stimulation and time-series microarray experiments. Our approach is composed of five steps (1) microarray experiments and data error analysis, (2) data clustering, (3) data smoothing and discretization, (4) network reverse engineering, and (5) network dynamics analysis and fingerprint identification. The technological outcome of this study is a suite of experimental protocols and computational tools that reverse engineer regulatory networks provided gene expression data. The practical biological outcome of this work is an immune response fingerprint in terms of gene expression levels. Inferring regulatory networks from microarray data is a new field of investigation that is no more than five years old. To the best of our knowledge, this work is the first attempt that integrates experiments, error analyses, data clustering, inference, and network analysis to solve a practical problem. Our systematic approach of counting, enumeration, and sampling networks matching experimental data is new to the field of network reverse engineering. The resulting mathematical analyses and computational tools lead to new results on their own and should be useful to others who analyze and infer networks.

  3. Reverse Engineering Boolean Networks: From Bernoulli Mixture Models to Rule Based Systems

    PubMed Central

    Saeed, Mehreen; Ijaz, Maliha; Javed, Kashif; Babri, Haroon Atique

    2012-01-01

    A Boolean network is a graphical model for representing and analyzing the behavior of gene regulatory networks (GRN). In this context, the accurate and efficient reconstruction of a Boolean network is essential for understanding the gene regulation mechanism and the complex relations that exist therein. In this paper we introduce an elegant and efficient algorithm for the reverse engineering of Boolean networks from a time series of multivariate binary data corresponding to gene expression data. We call our method ReBMM, i.e., reverse engineering based on Bernoulli mixture models. The time complexity of most of the existing reverse engineering techniques is quite high and depends upon the indegree of a node in the network. Due to the high complexity of these methods, they can only be applied to sparsely connected networks of small sizes. ReBMM has a time complexity factor, which is independent of the indegree of a node and is quadratic in the number of nodes in the network, a big improvement over other techniques and yet there is little or no compromise in accuracy. We have tested ReBMM on a number of artificial datasets along with simulated data derived from a plant signaling network. We also used this method to reconstruct a network from real experimental observations of microarray data of the yeast cell cycle. Our method provides a natural framework for generating rules from a probabilistic model. It is simple, intuitive and illustrates excellent empirical results. PMID:23284654

  4. Reverse engineering Boolean networks: from Bernoulli mixture models to rule based systems.

    PubMed

    Saeed, Mehreen; Ijaz, Maliha; Javed, Kashif; Babri, Haroon Atique

    2012-01-01

    A Boolean network is a graphical model for representing and analyzing the behavior of gene regulatory networks (GRN). In this context, the accurate and efficient reconstruction of a Boolean network is essential for understanding the gene regulation mechanism and the complex relations that exist therein. In this paper we introduce an elegant and efficient algorithm for the reverse engineering of Boolean networks from a time series of multivariate binary data corresponding to gene expression data. We call our method ReBMM, i.e., reverse engineering based on Bernoulli mixture models. The time complexity of most of the existing reverse engineering techniques is quite high and depends upon the indegree of a node in the network. Due to the high complexity of these methods, they can only be applied to sparsely connected networks of small sizes. ReBMM has a time complexity factor, which is independent of the indegree of a node and is quadratic in the number of nodes in the network, a big improvement over other techniques and yet there is little or no compromise in accuracy. We have tested ReBMM on a number of artificial datasets along with simulated data derived from a plant signaling network. We also used this method to reconstruct a network from real experimental observations of microarray data of the yeast cell cycle. Our method provides a natural framework for generating rules from a probabilistic model. It is simple, intuitive and illustrates excellent empirical results.

  5. A novel technique for presurgical nasoalveolar molding using computer-aided reverse engineering and rapid prototyping.

    PubMed

    Yu, Quan; Gong, Xin; Wang, Guo-Min; Yu, Zhe-Yuan; Qian, Yu-Fen; Shen, Gang

    2011-01-01

    To establish a new method of presurgical nasoalveolar molding (NAM) using computer-aided reverse engineering and rapid prototyping technique in infants with unilateral cleft lip and palate (UCLP). Five infants (2 males and 3 females with mean age of 1.2 w) with complete UCLP were recruited. All patients were subjected to NAM before the cleft lip repair. The upper denture casts were recorded using a three-dimensional laser scanner within 2 weeks after birth in UCLP infants. A digital model was constructed and analyzed to simulate the NAM procedure with reverse engineering software. The digital geometrical data were exported to print the solid model with rapid prototyping system. The whole set of appliances was fabricated based on these solid models. Laser scanning and digital model construction simplified the NAM procedure and estimated the treatment objective. The appliances were fabricated based on the rapid prototyping technique, and for each patient, the complete set of appliances could be obtained at one time. By the end of presurgical NAM treatment, the cleft was narrowed, and the malformation of nasoalveolar segments was aligned normally. We have developed a novel technique of presurgical NAM based on a computer-aided design. The accurate digital denture model of UCLP infants could be obtained with laser scanning. The treatment design and appliance fabrication could be simplified with a computer-aided reverse engineering and rapid prototyping technique.

  6. Metabolic Engineering of Microalgal Based Biofuel Production: Prospects and Challenges

    PubMed Central

    Banerjee, Chiranjib; Dubey, Kashyap K.; Shukla, Pratyoosh

    2016-01-01

    The current scenario in renewable energy is focused on development of alternate and sustainable energy sources, amongst which microalgae stands as one of the promising feedstock for biofuel production. It is well known that microalgae generate much larger amounts of biofuels in a shorter time than other sources based on plant seeds. However, the greatest challenge in a transition to algae-based biofuel production is the various other complications involved in microalgal cultivation, its harvesting, concentration, drying and lipid extraction. Several green microalgae accumulate lipids, especially triacylglycerols (TAGs), which are main precursors in the production of lipid. The various aspects on metabolic pathway analysis of an oleaginous microalgae i.e., Chlamydomonas reinhardtii have elucidated some novel metabolically important genes and this enhances the lipid production in this microalgae. Adding to it, various other aspects in metabolic engineering using OptFlux and effectual bioprocess design also gives an interactive snapshot of enhancing lipid production which ultimately improvises the oil yield. This article reviews the current status of microalgal based technologies for biofuel production, bioreactor process design, flux analysis and it also provides various strategies to increase lipids accumulation via metabolic engineering. PMID:27065986

  7. Environmental noise-a challenge for an acoustical engineer

    NASA Astrophysics Data System (ADS)

    Genuit, Klaus

    2003-10-01

    People live in a landscape full of noises which are composed of both natural environmental noises and technically created sounds. Regarding environmental noise, more and more people feel heavily annoyed by noises. Noise is defined as an audible sound which either disturbs the silence or an intentional sound listening or leads to annoyance. Thus, it is clearly defined that the assignment of noise cannot be reduced to simple determining objective parameters such as the A-weighted sound pressure level or the equivalent continuous sound pressure level. The question of whether a sound is judged as noise can only be made after the transformation from the sound event into an auditory event has been accomplished. The evaluation of noise depends on the physical characteristics of the sound event, on the psycho-acoustical features of the human ear, as well as on the psychological aspects of man. For the acoustical design of environmental noise and in order to create a better soundscape the acoustical engineer has to consider these aspects. That means a specific challenge for the sound engineering.

  8. Metabolic Engineering of Microalgal Based Biofuel Production: Prospects and Challenges.

    PubMed

    Banerjee, Chiranjib; Dubey, Kashyap K; Shukla, Pratyoosh

    2016-01-01

    The current scenario in renewable energy is focused on development of alternate and sustainable energy sources, amongst which microalgae stands as one of the promising feedstock for biofuel production. It is well known that microalgae generate much larger amounts of biofuels in a shorter time than other sources based on plant seeds. However, the greatest challenge in a transition to algae-based biofuel production is the various other complications involved in microalgal cultivation, its harvesting, concentration, drying and lipid extraction. Several green microalgae accumulate lipids, especially triacylglycerols (TAGs), which are main precursors in the production of lipid. The various aspects on metabolic pathway analysis of an oleaginous microalgae i.e., Chlamydomonas reinhardtii have elucidated some novel metabolically important genes and this enhances the lipid production in this microalgae. Adding to it, various other aspects in metabolic engineering using OptFlux and effectual bioprocess design also gives an interactive snapshot of enhancing lipid production which ultimately improvises the oil yield. This article reviews the current status of microalgal based technologies for biofuel production, bioreactor process design, flux analysis and it also provides various strategies to increase lipids accumulation via metabolic engineering.

  9. Challenges for reducing the size of laser activated remote phosphor light engines for DLP projection

    NASA Astrophysics Data System (ADS)

    Hartwig, Ulrich; Bruemmer, Mathias

    2014-12-01

    Laser activated remote phosphor (LARP) is an upcoming technology for high luminance SSL light engines. This presentation outlines some of the challenges met reducing the engine's size, so it can be retrofitted into DLP-projectors.

  10. Synthetic biology of metabolism: using natural variation to reverse engineer systems.

    PubMed

    Kliebenstein, Daniel J

    2014-06-01

    A goal of metabolic engineering is to take a plant and introduce new or modify existing pathways in a directed and predictable fashion. However, existing data does not provide the necessary level of information to allow for predictive models to be generated. One avenue to reverse engineer the necessary information is to study the genetic control of natural variation in plant primary and secondary metabolism. These studies are showing that any engineering model will have to incorporate information about 1000s of genes in both the nuclear and organellar genome to optimize the function of the introduced pathway. Further, these genes may interact in an unpredictable fashion complicating any engineering approach as it moves from the one or two gene manipulation to higher order stacking efforts. Finally, metabolic engineering may be influenced by a previously unrecognized potential for a plant to measure the metabolites within it. In combination, these observations from natural variation provide a beginning to help improve current efforts at metabolic engineering.

  11. Additional challenges for uncertainty analysis in river engineering

    NASA Astrophysics Data System (ADS)

    Berends, Koen; Warmink, Jord; Hulscher, Suzanne

    2016-04-01

    The management of rivers for improving safety, shipping and environment requires conscious effort on the part of river managers. River engineers design hydraulic works to tackle various challenges, from increasing flow conveyance to ensuring minimal water depths for environmental flow and inland shipping. Last year saw the completion of such large scale river engineering in the 'Room for the River' programme for the Dutch Rhine River system, in which several dozen of human interventions were built to increase flood safety. Engineering works in rivers are not completed in isolation from society. Rather, their benefits - increased safety, landscaping beauty - and their disadvantages - expropriation, hindrance - directly affect inhabitants. Therefore river managers are required to carefully defend their plans. The effect of engineering works on river dynamics is being evaluated using hydraulic river models. Two-dimensional numerical models based on the shallow water equations provide the predictions necessary to make decisions on designs and future plans. However, like all environmental models, these predictions are subject to uncertainty. In recent years progress has been made in the identification of the main sources of uncertainty for hydraulic river models. Two of the most important sources are boundary conditions and hydraulic roughness (Warmink et al. 2013). The result of these sources of uncertainty is that the identification of single, deterministic prediction model is a non-trivial task. This is this is a well-understood problem in other fields as well - most notably hydrology - and known as equifinality. However, the particular case of human intervention modelling with hydraulic river models compounds the equifinality case. The model that provides the reference baseline situation is usually identified through calibration and afterwards modified for the engineering intervention. This results in two distinct models, the evaluation of which yields the effect of

  12. Application and challenges of big data in quality monitoring of highway engineering

    NASA Astrophysics Data System (ADS)

    Xiao, Xianglin; Zhou, Chunrong

    2017-03-01

    Generation of big data brings opportunities and challenges to quality monitoring technologies of highway engineering. Big data of highway engineering quality monitoring is featured by typical "4V" characteristics. In order to deeply analyze application of big data in quality monitoring of highway engineering, the paper discusses generation, processing processes, key technologies as well as other aspects of big data of highway engineering quality monitoring. The paper analyzes storage structure, computing courses and data visualized processing processes of the big data of highway engineering quality monitoring and points out the problems and challenges encountered by application of big data in quality monitoring of highway engineering.

  13. Reverse Engineering: A Key Component of Systems Biology to Unravel Global Abiotic Stress Cross-Talk

    PubMed Central

    Friedel, Swetlana; Usadel, Björn; von Wirén, Nicolaus; Sreenivasulu, Nese

    2012-01-01

    Understanding the global abiotic stress response is an important stepping stone for the development of universal stress tolerance in plants in the era of climate change. Although co-occurrence of several stress factors (abiotic and biotic) in nature is found to be frequent, current attempts are poor to understand the complex physiological processes impacting plant growth under combinatory factors. In this review article, we discuss the recent advances of reverse engineering approaches that led to seminal discoveries of key candidate regulatory genes involved in cross-talk of abiotic stress responses and summarized the available tools of reverse engineering and its relevant application. Among the universally induced regulators involved in various abiotic stress responses, we highlight the importance of (i) abscisic acid (ABA) and jasmonic acid (JA) hormonal cross-talks and (ii) the central role of WRKY transcription factors (TF), potentially mediating both abiotic and biotic stress responses. Such interactome networks help not only to derive hypotheses but also play a vital role in identifying key regulatory targets and interconnected hormonal responses. To explore the full potential of gene network inference in the area of abiotic stress tolerance, we need to validate hypotheses by implementing time-dependent gene expression data from genetically engineered plants with modulated expression of target genes. We further propose to combine information on gene-by-gene interactions with data from physical interaction platforms such as protein–protein or TF-gene networks. PMID:23293646

  14. Reverse engineering: a key component of systems biology to unravel global abiotic stress cross-talk.

    PubMed

    Friedel, Swetlana; Usadel, Björn; von Wirén, Nicolaus; Sreenivasulu, Nese

    2012-01-01

    Understanding the global abiotic stress response is an important stepping stone for the development of universal stress tolerance in plants in the era of climate change. Although co-occurrence of several stress factors (abiotic and biotic) in nature is found to be frequent, current attempts are poor to understand the complex physiological processes impacting plant growth under combinatory factors. In this review article, we discuss the recent advances of reverse engineering approaches that led to seminal discoveries of key candidate regulatory genes involved in cross-talk of abiotic stress responses and summarized the available tools of reverse engineering and its relevant application. Among the universally induced regulators involved in various abiotic stress responses, we highlight the importance of (i) abscisic acid (ABA) and jasmonic acid (JA) hormonal cross-talks and (ii) the central role of WRKY transcription factors (TF), potentially mediating both abiotic and biotic stress responses. Such interactome networks help not only to derive hypotheses but also play a vital role in identifying key regulatory targets and interconnected hormonal responses. To explore the full potential of gene network inference in the area of abiotic stress tolerance, we need to validate hypotheses by implementing time-dependent gene expression data from genetically engineered plants with modulated expression of target genes. We further propose to combine information on gene-by-gene interactions with data from physical interaction platforms such as protein-protein or TF-gene networks.

  15. Engineering Risk Assessment of Space Thruster Challenge Problem

    NASA Technical Reports Server (NTRS)

    Mathias, Donovan L.; Mattenberger, Christopher J.; Go, Susie

    2014-01-01

    The Engineering Risk Assessment (ERA) team at NASA Ames Research Center utilizes dynamic models with linked physics-of-failure analyses to produce quantitative risk assessments of space exploration missions. This paper applies the ERA approach to the baseline and extended versions of the PSAM Space Thruster Challenge Problem, which investigates mission risk for a deep space ion propulsion system with time-varying thruster requirements and operations schedules. The dynamic mission is modeled using a combination of discrete and continuous-time reliability elements within the commercially available GoldSim software. Loss-of-mission (LOM) probability results are generated via Monte Carlo sampling performed by the integrated model. Model convergence studies are presented to illustrate the sensitivity of integrated LOM results to the number of Monte Carlo trials. A deterministic risk model was also built for the three baseline and extended missions using the Ames Reliability Tool (ART), and results are compared to the simulation results to evaluate the relative importance of mission dynamics. The ART model did a reasonable job of matching the simulation models for the baseline case, while a hybrid approach using offline dynamic models was required for the extended missions. This study highlighted that state-of-the-art techniques can adequately adapt to a range of dynamic problems.

  16. The bioartificial pancreas (BAP): Biological, chemical and engineering challenges.

    PubMed

    Iacovacci, Veronica; Ricotti, Leonardo; Menciassi, Arianna; Dario, Paolo

    2016-01-15

    The bioartificial pancreas (BAP) represents a viable solution for the treatment of type 1 diabetes (T1D). By encapsulating pancreatic cells in a semipermeable membrane to allow nutrient, insulin and glucose exchange, the side effects produced by islets and whole organ transplantation-related immunosuppressive therapy can be circumvented. Several factors, mainly related to materials properties, capsule morphology and biological environment, play a key role in optimizing BAP systems. The BAP is an extremely complex delivery system for insulin. Despite considerable efforts, in some instances meeting with limited degree of success, a BAP capable of restoring physiological pancreas functions without the need for immunosuppressive drugs and of controlling blood glucose levels especially in large animal models and a few clinical trials, does not exist. The state of the art in terms of materials, fabrication techniques and cell sources, as well as the current status of commercial devices and clinical trials, are described in this overview from an interdisciplinary viewpoint. In addition, challenges to the creation of effective BAP systems are highlighted including future perspectives in terms of component integration from both a biological and an engineering viewpoint.

  17. Gene therapy for haemophilia: prospects and challenges to prevent or reverse inhibitor formation.

    PubMed

    Scott, David W; Lozier, Jay N

    2012-02-01

    Monogenic hereditary diseases, such as haemophilia A and B, are ideal targets for gene therapeutic approaches. While these diseases can be treated with protein therapeutics, such as factor VIII (FVIII) or IX (FIX), the notion that permanent transfer of the genes encoding these factors can cure haemophilia is very attractive. An underlying problem with a gene therapy approach, however, is the patient's immune response to the therapeutic protein (as well as to the transmission vector), leading to the formation of inhibitory antibodies. Even more daunting is reversing an existing immune response in patients with pre-existing inhibitors. In this review, we will describe the laboratory and clinical progress, and the challenges met thus far, in achieving the goal of gene therapy efficacy, with a focus on the goal of tolerance induction.

  18. Prevention and reversal of type 1 diabetes--past challenges and future opportunities.

    PubMed

    Skyler, Jay S

    2015-06-01

    Over the past three decades there have been a number of clinical trials directed at interdicting the type 1 diabetes (T1D) disease process in an attempt to prevent the development of the disease in those at increased risk or to stabilize-potentially even reverse-the disease in people with T1D, usually of recent onset. Unfortunately, to date there has been no prevention trial that has resulted in delay or prevention of T1D. And, trials in people with T1D have had mixed results with some showing promise with at least transient improvement in β-cell function compared with randomized control groups, while others have failed to slow the decline in β-cell function when compared with placebo. This Perspective will assess the past and present challenges in this effort and provide an outline for potential future opportunities.

  19. Issues impacting genetic network reverse engineering algorithm validation using small networks.

    PubMed

    Vinh, Nguyen Xuan; Chetty, Madhu; Coppel, Ross; Wangikar, Pramod P

    2012-12-01

    Genetic network reverse engineering has been an area of intensive research within the systems biology community during the last decade. With many techniques currently available, the task of validating them and choosing the best one for a certain problem is a complex issue. Current practice has been to validate an approach on in-silico synthetic data sets, and, wherever possible, on real data sets with known ground-truth. In this study, we highlight a major issue that the validation of reverse engineering algorithms on small benchmark networks very often results in networks which are not statistically better than a randomly picked network. Another important issue highlighted is that with short time series, a small variation in the pre-processing procedure might yield large differences in the inferred networks. To demonstrate these issues, we have selected as our case study the IRMA in-vivo synthetic yeast network recently published in Cell. Using Fisher's exact test, we show that many results reported in the literature on reverse-engineering this network are not significantly better than random. The discussion is further extended to some other networks commonly used for validation purposes in the literature. The results presented in this study emphasize that studies carried out using small genetic networks are likely to be trivial, making it imperative that larger real networks be used for validating and benchmarking purposes. If smaller networks are considered, then the results should be interpreted carefully to avoid over confidence. This article is part of a Special Issue entitled: Computational Methods for Protein Interaction and Structural Prediction.

  20. A synthetic biology approach to engineer a functional reversal of the β-oxidation cycle.

    PubMed

    Clomburg, James M; Vick, Jacob E; Blankschien, Matthew D; Rodríguez-Moyá, María; Gonzalez, Ramon

    2012-11-16

    While we have recently constructed a functional reversal of the β-oxidation cycle as a platform for the production of fuels and chemicals by engineering global regulators and eliminating native fermentative pathways, the system-level approach used makes it difficult to determine which of the many deregulated enzymes are responsible for product synthesis. This, in turn, limits efforts to fine-tune the synthesis of specific products and prevents the transfer of the engineered pathway to other organisms. In the work reported here, we overcome the aforementioned limitations by using a synthetic biology approach to construct and functionally characterize a reversal of the β-oxidation cycle. This was achieved through the in vitro kinetic characterization of each functional unit of the core and termination pathways, followed by their in vivo assembly and functional characterization. With this approach, the four functional units of the core pathway, thiolase, 3-hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydratase, and acyl-CoA dehydrogenase/trans-enoyl-CoA reductase, were purified and kinetically characterized in vitro. When these four functional units were assembled in vivo in combination with thioesterases as the termination pathway, the synthesis of a variety of 4-C carboxylic acids from a one-turn functional reversal of the β-oxidation cycle was realized. The individual expression and modular construction of these well-defined core components exerted the majority of control over product formation, with only highly selective termination pathways resulting in shifts in product formation. Further control over product synthesis was demonstrated by overexpressing a long-chain thiolase that enables the operation of multiple turns of the reversal of the β-oxidation cycle and hence the synthesis of longer-chain carboxylic acids. The well-defined and self-contained nature of each functional unit makes the engineered reversal of the

  1. Reverse engineering gene networks using singular value decomposition and robust regression

    PubMed Central

    Yeung, M. K. Stephen; Tegnér, Jesper; Collins, James J.

    2002-01-01

    We propose a scheme to reverse-engineer gene networks on a genome-wide scale using a relatively small amount of gene expression data from microarray experiments. Our method is based on the empirical observation that such networks are typically large and sparse. It uses singular value decomposition to construct a family of candidate solutions and then uses robust regression to identify the solution with the smallest number of connections as the most likely solution. Our algorithm has O(log N) sampling complexity and O(N4) computational complexity. We test and validate our approach in a series of in numero experiments on model gene networks. PMID:11983907

  2. Reverse Engineering of Genome-wide Gene Regulatory Networks from Gene Expression Data.

    PubMed

    Liu, Zhi-Ping

    2015-02-01

    Transcriptional regulation plays vital roles in many fundamental biological processes. Reverse engineering of genome-wide regulatory networks from high-throughput transcriptomic data provides a promising way to characterize the global scenario of regulatory relationships between regulators and their targets. In this review, we summarize and categorize the main frameworks and methods currently available for inferring transcriptional regulatory networks from microarray gene expression profiling data. We overview each of strategies and introduce representative methods respectively. Their assumptions, advantages, shortcomings, and possible improvements and extensions are also clarified and commented.

  3. Reverse engineering of ECT probes for nondestructive evaluation of moving conductors

    NASA Astrophysics Data System (ADS)

    Porzig, Konstantin; Carlstedt, Matthias; Ziolkowski, Marek; Brauer, Hartmut; Toepfer, Hannes

    2014-02-01

    Numerical modeling of commercial ECT equipment requires preparatory work in reverse engineering. The reconstruction of given ECT probes was performed in terms of (i) geometry, (ii) material properties and source parameters, (iii) impedance computation. High-resolution X-ray images were taken in order to build appropriate CAD models of given ECT probes. An optimization strategy was applied in order to estimate the permeability of the magnetic shield as well as the supply current by means of measurement data of the magnetic flux density. Subsequently, normalized impedance calculations were performed and compared to measurements in generic benchmark models containing artificial defects.

  4. Reverse Engineering of Genome-wide Gene Regulatory Networks from Gene Expression Data

    PubMed Central

    Liu, Zhi-Ping

    2015-01-01

    Transcriptional regulation plays vital roles in many fundamental biological processes. Reverse engineering of genome-wide regulatory networks from high-throughput transcriptomic data provides a promising way to characterize the global scenario of regulatory relationships between regulators and their targets. In this review, we summarize and categorize the main frameworks and methods currently available for inferring transcriptional regulatory networks from microarray gene expression profiling data. We overview each of strategies and introduce representative methods respectively. Their assumptions, advantages, shortcomings, and possible improvements and extensions are also clarified and commented. PMID:25937810

  5. Using nonlinear optimization methods to reverse engineer liner material properties from EFP tests

    SciTech Connect

    Murphy, M.J.; Baker, E.L.

    1995-02-27

    The utility of variable metric nonlinear optimization methods for reverse engineering liner material constitutive modeling parameters is described. We use an effective new code created by coupling the nonlinear optimization code NLQPEB with the DYNA2D finite element hydrocode. The optimization code determines the ``best`` set of liner material properties by running DYNA2D in a loop, varying the liner model constitutive parameters, and minimizing the difference between the EFP profiles of the calculation and experiment. The results of four different EFP warhead tests with the same copper liner material are used to determine material parameters for the Steinberg-Guinan, Johnson-Cook, & Armstrong-Zerilli models. In a companion paper we describe the successful application of this methodology to the forward engineering of liner contours to achieve desired EFP shapes. The methodology of utilizing a coupled optimization/finite element code provides a significant improvement in warhead designs and the warhead design process.

  6. Get a Grip! A Middle School Engineering Challenge

    ERIC Educational Resources Information Center

    Olds, Suzanne A.; Harrell, Deborah A.; Valente, Michael E.

    2006-01-01

    Investigating the field of engineering offers the opportunity for interdisciplinary, hands-on, inquiry-based units that integrate real-world applications. However, many K-12 students are not exposed to engineering until they enter college. Get a Grip! is a problem-based unit that places middle school students in the role of engineers who are…

  7. High School Engineering and Technology Education Integration through Design Challenges

    ERIC Educational Resources Information Center

    Mentzer, Nathan

    2011-01-01

    This study contextualized the use of the engineering design process by providing descriptions of how each element in a design process was integrated in an eleventh grade industry and engineering systems course. The guiding research question for this inquiry was: How do students engage in the engineering design process in a course where technology…

  8. Get a Grip! A Middle School Engineering Challenge

    ERIC Educational Resources Information Center

    Olds, Suzanne A.; Harrell, Deborah A.; Valente, Michael E.

    2006-01-01

    Investigating the field of engineering offers the opportunity for interdisciplinary, hands-on, inquiry-based units that integrate real-world applications. However, many K-12 students are not exposed to engineering until they enter college. Get a Grip! is a problem-based unit that places middle school students in the role of engineers who are…

  9. Academic Preparedness as a Predictor of Achievement in an Engineering Design Challenge

    ERIC Educational Resources Information Center

    Mentzer, Nathan; Becker, Kurt

    2010-01-01

    The purpose of this study was to determine if a student's academic success, measured by grade point average (GPA) in mathematics, science, and communication courses, is correlated with student change in achievement during an engineering design challenge. Engineering design challenges have been implemented and researched in K-16 environments where…

  10. Reverse osmosis integrity monitoring in water reuse: The challenge to verify virus removal - A review.

    PubMed

    Pype, Marie-Laure; Lawrence, Michael G; Keller, Jurg; Gernjak, Wolfgang

    2016-07-01

    A reverse osmosis (RO) process is often included in the treatment train to produce high quality reuse water from treated effluent for potable purposes because of its high removal efficiency for salinity and many inorganic and organic contaminants, and importantly, it also provides an excellent barrier for pathogens. In order to ensure the continued protection of public health from pathogen contamination, monitoring RO process integrity is necessary. Due to their small sizes, viruses are the most difficult class of pathogens to be removed in physical separation processes and therefore often considered the most challenging pathogen to monitor. To-date, there is a gap between the current log credit assigned to this process (determined by integrity testing approved by regulators) and its actual log removal capability as proven in a variety of laboratory and pilot studies. Hence, there is a challenge to establish a methodology that more closely links to the theoretical performance. In this review, after introducing the notion of risk management in water reuse, we provide an overview of existing and potentially new RO integrity monitoring techniques, highlight their strengths and drawbacks, and debate their applicability to full-scale treatment plants, which open to future research opportunities.

  11. THE DIESEL ENGINE'S CHALLENGE IN THE NEW MILLENIUM

    SciTech Connect

    Fairbanks, John W.

    2000-08-20

    Diesel engines are the dominant propulsion engine of choice for most of the commercial surface transportation applications in the world. Consider agricultural uses: Diesel engine power is used to prepare the soil, transport the bulk seed or seedlings, pump irrigation water, and spray fertilizers, mechanically harvest some crops and distribute the produce to market. Diesel engines power virtually all of the off-highway construction equipment. Deep water commercial freighters or containerships are almost all diesel engine powered. The passenger ships are primarily either diesel or a combination of diesel and gas turbine, referred to as CODAG or CODOG.

  12. Engineering's Grand Challenges: Priorities and Integration Recommendations for Technology Education Curriculum Development

    ERIC Educational Resources Information Center

    Buelin, Jennifer; Clark, Aaron C.; Ernst, Jeremy V.

    2016-01-01

    In this study, the 14 Grand Challenges for Engineering in the 21st Century identified by the National Academy of Engineering were examined by a panel of experts in an effort to identify prospective curricular integration opportunities in the field of technology and engineering education. The study utilized a three-round modified Delphi methodology…

  13. Identifying the Challenging Factors in the Transition from Colleges of Engineering to Employment

    ERIC Educational Resources Information Center

    Baytiyeh, Hoda; Naja, Mohamad

    2012-01-01

    The transition from university to a career in engineering is a challenging process. This study examined the perceptions of engineering graduates regarding the difficulties they encountered in their transition from the university to the workplace. Lebanese practising engineers (n=217), living around the world, were surveyed to identify their…

  14. Identifying the challenging factors in the transition from colleges of engineering to employment

    NASA Astrophysics Data System (ADS)

    Baytiyeh, Hoda; Naja, Mohamad

    2012-03-01

    The transition from university to a career in engineering is a challenging process. This study examined the perceptions of engineering graduates regarding the difficulties they encountered in their transition from the university to the workplace. Lebanese practising engineers (n=217), living around the world, were surveyed to identify their current employment situations and their attitudes toward their academic preparation. Factor analysis revealed three main challenges facing engineering graduates: communication; responsibility; self-confidence. Seventeen interviews were conducted to gather information on ways to facilitate this transition. Comments reflected the need for better collaboration between engineering schools and engineering firms. The results will provide insight for engineering colleges, faculty members and administrators into the challenges faced by graduates and their aspirations for a smoother transition into employment.

  15. Challenges of bone tissue engineering in orthopaedic patients.

    PubMed

    Guerado, Enrique; Caso, Enrique

    2017-02-18

    Bone defects may impede normal biomechanics and the structural stability of bone as an organ. In many cases, the correction of bone defects requires extensive surgical intervention involving the use of bone-grafting techniques and other procedures in which healing is slow, there is a high risk of infection and considerable pain is provoked - with no guarantee of complete correction of the defect. Therefore, the search for surgical alternatives continues to present a major challenge in orthopaedic traumatology. The reamer-irrigator-aspirator (RIA) system, which was devised to avoid the problems that can arise with autograft harvesting from the iliac crest, consists of collecting the product of the femoral canal after reaming. The RIA technique improves osteogenic differentiation of mesenchymal stem cells, compared to bone marrow aspiration or cancellous bone harvesting from the iliac crest using a spoon. Another approach, the Masquelet technique, consists of reconstructing a long bone defect by means of an induced membrane grown onto an acrylic cement rod inserted to fill the defect; in a second surgical step, once the membrane is constituted, the cement rod is removed and cancellous autograft is used to fill the defect. Both in RIA and in the Masquelet technique, osteosynthesis is usually needed. Bone transportation by compression-distraction lengthening principles is commonly implemented for the treatment of large bone loss. However, complications are frequently encountered with these techniques. Among new techniques that have been proposed to address the problem of large bone loss, the application of stem cells in conjunction with tissue engineering techniques is very promising, as is the creation of personalised medicine (or precision medicine), in which molecular profiling technologies are used to tailor the therapeutic strategy, to ensure the right method is applied for the right person at the right time, after determining the predisposition to disease among

  16. Challenges of bone tissue engineering in orthopaedic patients

    PubMed Central

    Guerado, Enrique; Caso, Enrique

    2017-01-01

    Bone defects may impede normal biomechanics and the structural stability of bone as an organ. In many cases, the correction of bone defects requires extensive surgical intervention involving the use of bone-grafting techniques and other procedures in which healing is slow, there is a high risk of infection and considerable pain is provoked - with no guarantee of complete correction of the defect. Therefore, the search for surgical alternatives continues to present a major challenge in orthopaedic traumatology. The reamer-irrigator-aspirator (RIA) system, which was devised to avoid the problems that can arise with autograft harvesting from the iliac crest, consists of collecting the product of the femoral canal after reaming. The RIA technique improves osteogenic differentiation of mesenchymal stem cells, compared to bone marrow aspiration or cancellous bone harvesting from the iliac crest using a spoon. Another approach, the Masquelet technique, consists of reconstructing a long bone defect by means of an induced membrane grown onto an acrylic cement rod inserted to fill the defect; in a second surgical step, once the membrane is constituted, the cement rod is removed and cancellous autograft is used to fill the defect. Both in RIA and in the Masquelet technique, osteosynthesis is usually needed. Bone transportation by compression-distraction lengthening principles is commonly implemented for the treatment of large bone loss. However, complications are frequently encountered with these techniques. Among new techniques that have been proposed to address the problem of large bone loss, the application of stem cells in conjunction with tissue engineering techniques is very promising, as is the creation of personalised medicine (or precision medicine), in which molecular profiling technologies are used to tailor the therapeutic strategy, to ensure the right method is applied for the right person at the right time, after determining the predisposition to disease among

  17. The development of a program analysis environment for Ada: Reverse engineering tools for Ada

    NASA Technical Reports Server (NTRS)

    Cross, James H., II

    1991-01-01

    The Graphical Representations of Algorithms, Structures, and Processes for Ada (GRASP/Ada) has successfully created and prototyped a new algorithm level graphical representation for Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and thus improve reliability and reduce costs. The emphasis was on the automatic generation of the CSD from Ada source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada source code. In Phase 1 of the GRASP/Ada project, the CSD graphical constructs were created and applied manually to several small Ada programs. A prototype (Version 1) was designed and implemented using FLEX and BISON running under the Virtual Memory System (VMS) on a VAX 11-780. In Phase 2, the prototype was improved and ported to the Sun 4 platform under UNIX. A user interface was designed and partially implemented. The prototype was applied successfully to numerous Ada programs ranging in size from several hundred to several thousand lines of source code. In Phase 3 of the project, the prototype was prepared for limited distribution (GRASP/Ada Version 3.0) to facilitate evaluation. The user interface was extensively reworked. The current prototype provides the capability for the user to generate CSD from Ada source code in a reverse engineering mode with a level of flexibility suitable for practical application.

  18. Reverse-engineering a watermark detector based on a more precise model

    NASA Astrophysics Data System (ADS)

    Yu, Jun; Craver, Scott

    2010-01-01

    Detection results obtained from an oracle can be used to reverse-engineer the underlying detector structure, or parameters thereof. In particular, if a detector uses a common structure like correlation or normalized correlation, detection results can be used to estimate feature space dimensionality, watermark strength, and detector threshold values. Previous estimation techniques used a simplistic but tractable model for a watermarked image in the detection cone of a normalized correlation detector; in particular a watermarked image is assumed to lie along the axis of the detection cone, essentially corresponding to an image of zero magnitude. This produced useful results for feature spaces of fewer dimensions, but increasingly imprecise estimates for larger feature spaces. In this paper we model the watermarked image properly as a sum of a cover vector and approximately orthogonal watermark vector, offsetting the image within the cone, which is the geometry of a detector using normalized correlation. This symmetry breaking produces a far more complex model which boils down to a quartic equation. Although it is infeasible to find its symbolic solution even with the aid of computer, our numerical analysis results show certain critical behavior which reveals the relationship between the attacking noise strength and the detector parameters. The critical behavior predicted by our model extends our reverse-engineering capability to the case of detectors with large feature space dimensions, which is not uncommon in multimedia watermarking algorithms.

  19. Qualification of a 3D structured light sensor for a reverse engineering application

    NASA Astrophysics Data System (ADS)

    Guarato, Alexandre Z.; Loja, Alexandre C.; Pereira, Leonardo P.; Braga, Sergio L.; Trevilato, Thales R. B.

    2016-11-01

    This paper deals with the qualification of a 3D structured light scanning system for an application of reverse engineering of a mechanical part. As this white light scanner is an electro-optical device and based on the principle of optical triangulation, the measurement accuracy is affected by the measured part geometry and its position within the scanning window. The effects of the scan depth and the projected angle, characterizing the surface normal of the measured surface to the scanning point of view, on the measurement of accuracy are not considered in the standard calibration process of manufacturers and have been identified by experiments in the present work. The digitization errors are analyzed and characterized thanks to a measurement protocol based on quality indicators. Theses quality indicators are evaluated thanks to simple calibrated artifacts. The aim of this work is to redefine the ideal relative distance and relative angle for minimizing the digitizing errors in relation to those stated by the manufacturer for a reverse engineering application.

  20. Quality assessment of reverse engineering process based on full-field true-3D optical measurements

    NASA Astrophysics Data System (ADS)

    Kujawinska, Malgorzata; Sitnik, Robert

    2000-08-01

    In the paper the sequential steps of reverse engineering based on the data gathered by full-field optical system are discussed. Each step is concerned from the point of view of its influence on the final quality of the shape of manufactured object. At first the modern shape measurement system based on the combination of fringe projection, Grey code and experimental calibration is presented. The system enables the determination of absolute coordinates of the object measured from many directions. The dependence of the quality of the cloud of points on the type of object and the measurement procedure is discussed. Then the methods of transferring the experimental data into CAD/CAM/CAE system are presented. The quality of the virtual object in the form of closed triangular mesh is analyzed. Basing on this virtual object the copy of initial body is produced and measured. The accuracy of the object manufactured is determined and the main sources of errors are discussed. The modifications of the system and algorithms that minimize the errors are proposed. The reverse engineering sequence is presented is illustrated by several examples.

  1. A shape-based inter-layer contours correspondence method for ICT-based reverse engineering

    PubMed Central

    Duan, Liming; Yang, Shangpeng; Zhang, Gui; Feng, Fei; Gu, Minghui

    2017-01-01

    The correspondence of a stack of planar contours in ICT (industrial computed tomography)-based reverse engineering, a key step in surface reconstruction, is difficult when the contours or topology of the object are complex. Given the regularity of industrial parts and similarity of the inter-layer contours, a specialized shape-based inter-layer contours correspondence method for ICT-based reverse engineering was presented to solve the above problem based on the vectorized contours. In this paper, the vectorized contours extracted from the slices consist of three graphical primitives: circles, arcs and segments. First, the correspondence of the inter-layer primitives is conducted based on the characteristics of the primitives. Second, based on the corresponded primitives, the inter-layer contours correspond with each other using the proximity rules and exhaustive search. The proposed method can make full use of the shape information to handle industrial parts with complex structures. The feasibility and superiority of this method have been demonstrated via the related experiments. This method can play an instructive role in practice and provide a reference for the related research. PMID:28489867

  2. A shape-based inter-layer contours correspondence method for ICT-based reverse engineering.

    PubMed

    Duan, Liming; Yang, Shangpeng; Zhang, Gui; Feng, Fei; Gu, Minghui

    2017-01-01

    The correspondence of a stack of planar contours in ICT (industrial computed tomography)-based reverse engineering, a key step in surface reconstruction, is difficult when the contours or topology of the object are complex. Given the regularity of industrial parts and similarity of the inter-layer contours, a specialized shape-based inter-layer contours correspondence method for ICT-based reverse engineering was presented to solve the above problem based on the vectorized contours. In this paper, the vectorized contours extracted from the slices consist of three graphical primitives: circles, arcs and segments. First, the correspondence of the inter-layer primitives is conducted based on the characteristics of the primitives. Second, based on the corresponded primitives, the inter-layer contours correspond with each other using the proximity rules and exhaustive search. The proposed method can make full use of the shape information to handle industrial parts with complex structures. The feasibility and superiority of this method have been demonstrated via the related experiments. This method can play an instructive role in practice and provide a reference for the related research.

  3. DeGNServer: deciphering genome-scale gene networks through high performance reverse engineering analysis.

    PubMed

    Li, Jun; Wei, Hairong; Zhao, Patrick Xuechun

    2013-01-01

    Analysis of genome-scale gene networks (GNs) using large-scale gene expression data provides unprecedented opportunities to uncover gene interactions and regulatory networks involved in various biological processes and developmental programs, leading to accelerated discovery of novel knowledge of various biological processes, pathways and systems. The widely used context likelihood of relatedness (CLR) method based on the mutual information (MI) for scoring the similarity of gene pairs is one of the accurate methods currently available for inferring GNs. However, the MI-based reverse engineering method can achieve satisfactory performance only when sample size exceeds one hundred. This in turn limits their applications for GN construction from expression data set with small sample size. We developed a high performance web server, DeGNServer, to reverse engineering and decipher genome-scale networks. It extended the CLR method by integration of different correlation methods that are suitable for analyzing data sets ranging from moderate to large scale such as expression profiles with tens to hundreds of microarray hybridizations, and implemented all analysis algorithms using parallel computing techniques to infer gene-gene association at extraordinary speed. In addition, we integrated the SNBuilder and GeNa algorithms for subnetwork extraction and functional module discovery. DeGNServer is publicly and freely available online.

  4. Systematic reverse engineering of network topologies: a case study of resettable bistable cellular responses.

    PubMed

    Mondal, Debasish; Dougherty, Edward; Mukhopadhyay, Abhishek; Carbo, Adria; Yao, Guang; Xing, Jianhua

    2014-01-01

    A focused theme in systems biology is to uncover design principles of biological networks, that is, how specific network structures yield specific systems properties. For this purpose, we have previously developed a reverse engineering procedure to identify network topologies with high likelihood in generating desired systems properties. Our method searches the continuous parameter space of an assembly of network topologies, without enumerating individual network topologies separately as traditionally done in other reverse engineering procedures. Here we tested this CPSS (continuous parameter space search) method on a previously studied problem: the resettable bistability of an Rb-E2F gene network in regulating the quiescence-to-proliferation transition of mammalian cells. From a simplified Rb-E2F gene network, we identified network topologies responsible for generating resettable bistability. The CPSS-identified topologies are consistent with those reported in the previous study based on individual topology search (ITS), demonstrating the effectiveness of the CPSS approach. Since the CPSS and ITS searches are based on different mathematical formulations and different algorithms, the consistency of the results also helps cross-validate both approaches. A unique advantage of the CPSS approach lies in its applicability to biological networks with large numbers of nodes. To aid the application of the CPSS approach to the study of other biological systems, we have developed a computer package that is available in Information S1.

  5. Parameter estimation in spiking neural networks: a reverse-engineering approach.

    PubMed

    Rostro-Gonzalez, H; Cessac, B; Vieville, T

    2012-04-01

    This paper presents a reverse engineering approach for parameter estimation in spiking neural networks (SNNs). We consider the deterministic evolution of a time-discretized network with spiking neurons, where synaptic transmission has delays, modeled as a neural network of the generalized integrate and fire type. Our approach aims at by-passing the fact that the parameter estimation in SNN results in a non-deterministic polynomial-time hard problem when delays are to be considered. Here, this assumption has been reformulated as a linear programming (LP) problem in order to perform the solution in a polynomial time. Besides, the LP problem formulation makes the fact that the reverse engineering of a neural network can be performed from the observation of the spike times explicit. Furthermore, we point out how the LP adjustment mechanism is local to each neuron and has the same structure as a 'Hebbian' rule. Finally, we present a generalization of this approach to the design of input-output (I/O) transformations as a practical method to 'program' a spiking network, i.e. find a set of parameters allowing us to exactly reproduce the network output, given an input. Numerical verifications and illustrations are provided.

  6. Reverse Engineering of Vaccine Antigens Using High Throughput Sequencing-enhanced mRNA Display

    PubMed Central

    Guo, Nini; Duan, Hongying; Kachko, Alla; Krause, Benjamin W.; Major, Marian E.; Krause, Philip R.

    2015-01-01

    Vaccine reverse engineering is emerging as an important approach to vaccine antigen identification, recently focusing mainly on structural characterization of interactions between neutralizing monoclonal antibodies (mAbs) and antigens. Using mAbs that bind unknown antigen structures, we sought to probe the intrinsic features of antibody antigen-binding sites with a high complexity peptide library, aiming to identify conformationally optimized mimotope antigens that capture mAb-specific epitopes. Using a high throughput sequencing-enhanced messenger ribonucleic acid (mRNA) display approach, we identified high affinity binding peptides for a hepatitis C virus neutralizing mAb. Immunization with the selected peptides induced neutralizing activity similar to that of the original mAb. Antibodies elicited by the most commonly selected peptides were predominantly against specific epitopes. Thus, using mRNA display to interrogate mAbs permits high resolution identification of functional peptide antigens that direct targeted immune responses, supporting its use in vaccine reverse engineering for pathogens against which potent neutralizing mAbs are available. Research in Context We used a large number of randomly produced small proteins (“peptides”) to identify peptides containing specific protein sequences that bind efficiently to an antibody that can prevent hepatitis C virus infection in cell culture. After the identified peptides were injected into mice, the mice produced their own antibodies with characteristics similar to the original antibody. This approach can provide previously unavailable information about antibody binding and could also be useful in developing new vaccines. PMID:26425692

  7. Route towards the optimization at given power of thermoelectric heat engines with broken time-reversal symmetry

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Li, Qian-Wen; Tang, F. R.; Yang, X. Q.; Bai, L.

    2017-08-01

    We investigate the performance at a given power of a thermoelectric heat engine with broken time-reversal symmetry, and derive analytically the efficiency at a given power of a thermoelectric generator within linear irreversible thermodynamics. A universal bound on the efficiency of the thermoelectric heat engine is achieved under a strong constraint on the Onsager coefficients, and some interesting features are further revealed. Our results demonstrate that there exists a trade-off between efficiency and power output, and the efficiency at a given power may surpass the Curzon-Ahlborn limit due to broken time-reversal symmetry. Moreover, optimal efficiency at a given power can be achieved, which indicates that broken time-reversal symmetry offers physically allowed ways to optimize the performance of heat engines. Our study may contribute to the interesting guidelines for optimizing actual engines.

  8. Reverse engineering of free-form surface based on the closed-loop theory.

    PubMed

    He, Xue Ming; He, Jun Fei; Wu, Mei Ping; Zhang, Rong; Ji, Xiao Gang

    2015-01-01

    To seek better methods of measurement and more accurate model of reconstruction in the field of reverse engineering has been the focus of researchers. Based on this, a new method of adaptive measurement, real-time reconstruction, and online evaluation of free-form surface was presented in this paper. The coordinates and vectors of the prediction points are calculated according to a Bézier curve which is fitted by measured points. Final measured point cloud distribution is in agreement with the geometric characteristics of the free-form surfaces. Fitting the point cloud to a surface model by the nonuniform B-spline method, extracting some check points from the surface models based on grids and a feature on the surface, review the location of these check points on the surface with CMM and evaluate the model, and then update the surface model to meet the accuracy. Integrated measurement, reconstruction, and evaluation, with the closed-loop reverse process, established an accurate model. The results of example show that the measuring points are distributed over the surface according to curvature, and the reconstruction model can be completely expressed with micron level. Meanwhile, measurement, reconstruction and evaluation are integrated in forms of closed-loop reverse system.

  9. Reversible Tuning of Individual Carbon Nanotube Mechanical Properties via Defect Engineering.

    PubMed

    Zhang, Bin; Zhao, Longze; Cheng, Yong; Golberg, Dmitri; Wang, Ming-Sheng

    2016-08-10

    The structural defects that inevitably exist in real-world carbon nanotubes (CNTs) are generally considered undesirable because they break the structural perfection and may result in drastically degraded CNT properties. On the other hand, the deliberate defect introduction can provide a possibility to tailor the tube mechanical properties. Herein, we present a fully controllable technique to handle defects by using in situ transmission electron microscopy (TEM). Young's modulus, quality factor of the resonation and tensile strength of CNTs can be controllably, reversibly, and repeatedly tuned. Parallel high-resolution visualizing of structural defects suggests that the property tuning cycles are primarily attributed to the reversible conversion of defects at the atomic scale: the defects are created in the form of vacancies and interstitials under electron irradiation, and they vanish through the recombination via current-induced annealing. For applications, such as reversible frequency-tuned CNT resonators, this defect-engineering technique is demonstrated to be uniquely precise; the frequency may be tuned with 0.1%/min accuracy, improved by 1 order of magnitude compared with the existing approaches. We believe that these results will be highly valuable in a variety of property-tunable CNT-based composites and devices.

  10. Teacher Challenges to Implement Engineering Design in Secondary Technology Education

    ERIC Educational Resources Information Center

    Kelley, Todd R.; Wicklein, Robert C.

    2009-01-01

    This descriptive study examined the current status of technology education teacher practices with respect to engineering design. This article is the third article in a three-part series presenting the results of this study. The first article in the series titled "Examination of Engineering Design Curriculum Content" highlighted the research…

  11. Engineering central metabolism - a grand challenge for plant biologists.

    PubMed

    Sweetlove, Lee J; Nielsen, Jens; Fernie, Alisdair R

    2016-12-22

    The goal of increasing crop productivity and nutrient-use efficiency is being addressed by a number of ambitious research projects seeking to re-engineer photosynthetic biochemistry. Many of these projects will require the engineering of substantial changes in fluxes of central metabolism. However, as has been amply demonstrated in simpler systems such as microbes, central metabolism is extremely difficult to rationally engineer. This is because of multiple layers of regulation that operate to maintain metabolic steady state and because of the highly connected nature of central metabolism. In this review we discuss new approaches for metabolic engineering that have the potential to address these problems and dramatically improve the success with which we can rationally engineer central metabolism in plants. In particular, we advocate the adoption of an iterative 'design-build-test-learn' cycle using fast-to-transform model plants as test beds. This approach can be realised by coupling new molecular tools to incorporate multiple transgenes in nuclear and plastid genomes with computational modelling to design the engineering strategy and to understand the metabolic phenotype of the engineered organism. We also envisage that mutagenesis could be used to fine-tune the balance between the endogenous metabolic network and the introduced enzymes. Finally, we emphasise the importance of considering the plant as a whole system and not isolated organs: the greatest increase in crop productivity will be achieved if both source and sink metabolism are engineered.

  12. Tissue Engineering-Current Challenges and Expanding Opportunities

    NASA Astrophysics Data System (ADS)

    Griffith, Linda G.; Naughton, Gail

    2002-02-01

    Tissue engineering can be used to restore, maintain, or enhance tissues and organs. The potential impact of this field, however, is far broader-in the future, engineered tissues could reduce the need for organ replacement, and could greatly accelerate the development of new drugs that may cure patients, eliminating the need for organ transplants altogether.

  13. Integrating Engineering Design Challenges into Secondary STEM Education

    ERIC Educational Resources Information Center

    Carr, Ronald L.; Strobel, Johannes

    2011-01-01

    Engineering is being currently taught in the full spectrum of the P-12 system, with an emphasis on design-oriented teaching (Brophy, Klein, Portsmore, & Rogers, 2008). Due to only a small amount of research on the learning of engineering design in elementary and middle school settings, the community of practice lacks the necessary knowledge of the…

  14. Growth of Engineering Education in India: Status, Issues, and Challenges

    ERIC Educational Resources Information Center

    Choudhury, Pradeep Kumar

    2016-01-01

    This article examines the growth of engineering education in India in the post-economic reform period using the secondary data published by Ministry of Human Resource Development, University Grants Commission and All India Council for Technical Education. Particularly, this article has focused on three important dimensions of engineering and…

  15. Growth of Engineering Education in India: Status, Issues, and Challenges

    ERIC Educational Resources Information Center

    Choudhury, Pradeep Kumar

    2016-01-01

    This article examines the growth of engineering education in India in the post-economic reform period using the secondary data published by Ministry of Human Resource Development, University Grants Commission and All India Council for Technical Education. Particularly, this article has focused on three important dimensions of engineering and…

  16. Crystal Engineering of HIV-1 Reverse Transcriptase for structure-Based Drug Design

    SciTech Connect

    Bauman,J.; Das, K.; Ho, W.; Baweja, M.; Himmel, D.; Clark, A.; Oren, D.; Shatkin, A.; Arnold, E.

    2008-01-01

    HIV-1 reverse transcriptase (RT) is a primary target for anti-AIDS drugs. Structures of HIV-1 RT, usually determined at {approx}2.5-3.0 Angstroms resolution, are important for understanding enzyme function and mechanisms of drug resistance in addition to being helpful in the design of RT inhibitors. Despite hundreds of attempts, it was not possible to obtain the structure of a complex of HIV-1 RT with TMC278, a nonnucleoside RT inhibitor (NNRTI) in advanced clinical trials. A systematic and iterative protein crystal engineering approach was developed to optimize RT for obtaining crystals in complexes with TMC278 and other NNRTIs that diffract X-rays to 1.8 Angstroms resolution. Another form of engineered RT was optimized to produce a high-resolution apo-RT crystal form, reported here at 1.85 Angstroms resolution, with a distinct RT conformation. Engineered RTs were mutagenized using a new, flexible and cost effective method called methylated overlap-extension ligation independent cloning. Our analysis suggests that reducing the solvent content, increasing lattice contacts, and stabilizing the internal low-energy conformations of RT are critical for the growth of crystals that diffract to high resolution. The new RTs enable rapid crystallization and yield high-resolution structures that are useful in designing/developing new anti-AIDS drugs.

  17. Crystal engineering of HIV-1 reverse transcriptase for structure-based drug design.

    PubMed

    Bauman, Joseph D; Das, Kalyan; Ho, William C; Baweja, Mukta; Himmel, Daniel M; Clark, Arthur D; Oren, Deena A; Boyer, Paul L; Hughes, Stephen H; Shatkin, Aaron J; Arnold, Eddy

    2008-09-01

    HIV-1 reverse transcriptase (RT) is a primary target for anti-AIDS drugs. Structures of HIV-1 RT, usually determined at approximately 2.5-3.0 A resolution, are important for understanding enzyme function and mechanisms of drug resistance in addition to being helpful in the design of RT inhibitors. Despite hundreds of attempts, it was not possible to obtain the structure of a complex of HIV-1 RT with TMC278, a nonnucleoside RT inhibitor (NNRTI) in advanced clinical trials. A systematic and iterative protein crystal engineering approach was developed to optimize RT for obtaining crystals in complexes with TMC278 and other NNRTIs that diffract X-rays to 1.8 A resolution. Another form of engineered RT was optimized to produce a high-resolution apo-RT crystal form, reported here at 1.85 A resolution, with a distinct RT conformation. Engineered RTs were mutagenized using a new, flexible and cost effective method called methylated overlap-extension ligation independent cloning. Our analysis suggests that reducing the solvent content, increasing lattice contacts, and stabilizing the internal low-energy conformations of RT are critical for the growth of crystals that diffract to high resolution. The new RTs enable rapid crystallization and yield high-resolution structures that are useful in designing/developing new anti-AIDS drugs.

  18. Engineering and Technology Challenges for Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2011-01-01

    After more than fifty years of space activities, the near-Earth environment is polluted with man-made orbital debris. The collision between Cosmos 2251 and the operational Iridium 33 in 2009 signaled a potential collision cascade effect, also known as the "Kessler Syndrome", in the environment. Various modelling studies have suggested that the commonly-adopted mitigation measures will not be sufficient to stabilize the future debris population. Active debris removal must be considered to remediate the environment. This paper summarizes the key issues associated with debris removal and describes the technology and engineering challenges to move forward. Fifty-four years after the launch of Sputnik 1, satellites have become an integral part of human society. Unfortunately, the ongoing space activities have left behind an undesirable byproduct orbital debris. This environment problem is threatening the current and future space activities. On average, two Shuttle window panels are replaced after every mission due to damage by micrometeoroid or orbital debris impacts. More than 100 collision avoidance maneuvers were conducted by satellite operators in 2010 to reduce the impact risks of their satellites with respect to objects in the U.S. Space Surveillance Network (SSN) catalog. Of the four known accident collisions between objects in the SSN catalog, the last one, collision between Cosmos 2251 and the operational Iridium 33 in 2009, was the most significant. It was the first ever accidental catastrophic destruction of an operational satellite by another satellite. It also signaled the potential collision cascade effect in the environment, commonly known as the "Kessler Syndrome," predicted by Kessler and Cour-Palais in 1978 [1]. Figure 1 shows the historical increase of objects in the SSN catalog. The majority of the catalog objects are 10 cm and larger. As of April 2011, the total objects tracked by the SSN sensors were more than 22,000. However, approximately 6000 of

  19. Medical and biological engineering in the next 20 years: the promise and the challenges.

    PubMed

    2013-07-01

    In 2011, the American Institute for Medical and Biological Engineering (AIMBE) (www.aimbe.org) celebrated its 20th anniversary by undertaking to identify major societal challenges to which medical and biological engineers can contribute solutions in the next 20 years. This report is a summary of the six major challenges that were identified. The report also discusses some specific areas within these high-level challenges that can form the basis for policy action, provides a brief rationale for pursuing those areas, and discusses roadblocks to progress. The six overarching challenges are: 1) engineering safe and sustainable water and food supply, 2) engineering personalized health care, 3) engineering solutions to injury and chronic diseases, 4) engineering global health through infectious disease prevention and therapy, 5) engineering sustainable bioenergy production, and 6) engineering the 21st century US economy. While arrived at independently by AIMBE, many of the elements overlap with similar challenges identified by other bodies. The similarities highlight the central mission of medical and biological engineers, working with other experts, which is to solve important problems central to human health and welfare.

  20. Reverse engineering of machine-tool settings with modified roll for spiral bevel pinions

    NASA Astrophysics Data System (ADS)

    Liu, Guanglei; Chang, Kai; Liu, Zeliang

    2013-05-01

    Although a great deal of research has been dedicated to the synthesis of spiral bevel gears, little related to reverse engineering can be found. An approach is proposed to reverse the machine-tool settings of the pinion of a spiral bevel gear drive on the basis of the blank and tooth surface data obtained by a coordinate measuring machine(CMM). Real tooth contact analysis(RTCA) is performed to preliminary ascertain the contact pattern, the motion curve, as well as the position of the mean contact point. And then the tangent to the contact path and the motion curve are interpolated in the sense of the least square method to extract the initial values of the bias angle and the higher order coefficients(HOC) in modified roll motion. A trial tooth surface is generated by machine-tool settings derived from the local synthesis relating to the initial meshing performances and modified roll motion. An optimization objective is formed which equals the tooth surface deviation between the real tooth surface and the trial tooth surface. The design variables are the parameters describing the meshing performances at the mean contact point in addition to the HOC. When the objective is optimized within an arbitrarily given convergence tolerance, the machine-tool settings together with the HOC are obtained. The proposed approach is verified by a spiral bevel pinion used in the accessory gear box of an aviation engine. The trial tooth surfaces approach to the real tooth surface on the whole in the example. The results show that the convergent tooth surface deviation for the concave side on the average is less than 0.5 μm, and is less than 1.3 μm for the convex side. The biggest tooth surface deviation is 6.7 μm which is located at the corner of the grid on the convex side. Those nodes with relative bigger tooth surface deviations are all located at the boundary of the grid. An approach is proposed to figure out the machine-tool settings of a spiral bevel pinion by way of reverse

  1. [Tissue engineering of heart valves: new opportunities and challenges].

    PubMed

    Bobylev, D O; Chebotar', S; Tudorake, I; Khaverikh, A

    2011-01-01

    Replacement of heart valves appears to be prevailing method of surgical correction of end stage valvular heart defects. Main drawback of contemporary artificial valves is lack of growth, potential for remodeling, and inclination to degeneration. To overcome these limitations the modern science in the last decade focuses on tissue engineering of valves as an alternative to their prostheses. Basic idea of the technique is the use of decellularized xenogenic allogenic matrix or biopolymers seeded with autologous cells under special conditions created in bioreactor. This literature review is devoted to a novel direction in experimental cardiosurgery - tissue engineering of heart valves which in a unique way combines biological, engineering, and technological achievements.

  2. Modeling Planarian Regeneration: A Primer for Reverse-Engineering the Worm

    PubMed Central

    Lobo, Daniel; Beane, Wendy S.; Levin, Michael

    2012-01-01

    A mechanistic understanding of robust self-assembly and repair capabilities of complex systems would have enormous implications for basic evolutionary developmental biology as well as for transformative applications in regenerative biomedicine and the engineering of highly fault-tolerant cybernetic systems. Molecular biologists are working to identify the pathways underlying the remarkable regenerative abilities of model species that perfectly regenerate limbs, brains, and other complex body parts. However, a profound disconnect remains between the deluge of high-resolution genetic and protein data on pathways required for regeneration, and the desired spatial, algorithmic models that show how self-monitoring and growth control arise from the synthesis of cellular activities. This barrier to progress in the understanding of morphogenetic controls may be breached by powerful techniques from the computational sciences—using non-traditional modeling approaches to reverse-engineer systems such as planaria: flatworms with a complex bodyplan and nervous system that are able to regenerate any body part after traumatic injury. Currently, the involvement of experts from outside of molecular genetics is hampered by the specialist literature of molecular developmental biology: impactful collaborations across such different fields require that review literature be available that presents the key functional capabilities of important biological model systems while abstracting away from the often irrelevant and confusing details of specific genes and proteins. To facilitate modeling efforts by computer scientists, physicists, engineers, and mathematicians, we present a different kind of review of planarian regeneration. Focusing on the main patterning properties of this system, we review what is known about the signal exchanges that occur during regenerative repair in planaria and the cellular mechanisms that are thought to underlie them. By establishing an engineering

  3. Precision Genome Engineering and Agriculture: Opportunities and Regulatory Challenges

    PubMed Central

    Voytas, Daniel F.; Gao, Caixia

    2014-01-01

    Plant agriculture is poised at a technological inflection point. Recent advances in genome engineering make it possible to precisely alter DNA sequences in living cells, providing unprecedented control over a plant's genetic material. Potential future crops derived through genome engineering include those that better withstand pests, that have enhanced nutritional value, and that are able to grow on marginal lands. In many instances, crops with such traits will be created by altering only a few nucleotides among the billions that comprise plant genomes. As such, and with the appropriate regulatory structures in place, crops created through genome engineering might prove to be more acceptable to the public than plants that carry foreign DNA in their genomes. Public perception and the performance of the engineered crop varieties will determine the extent to which this powerful technology contributes towards securing the world's food supply. PMID:24915127

  4. Computer-aided tissue engineering: overview, scope and challenges.

    PubMed

    Sun, Wei; Darling, Andrew; Starly, Binil; Nam, Jae

    2004-02-01

    Advances in computer-aided technology and its application with biology, engineering and information science to tissue engineering have evolved a new field of computer-aided tissue engineering (CATE). This emerging field encompasses computer-aided design (CAD), image processing, manufacturing and solid free-form fabrication (SFF) for modelling, designing, simulation and manufacturing of biological tissue and organ substitutes. The present Review describes some salient advances in this field, particularly in computer-aided tissue modeling, computer-aided tissue informatics and computer-aided tissue scaffold design and fabrication. Methodologies of development of CATE modelling from high-resolution non-invasive imaging and image-based three-dimensional reconstruction, and various reconstructive techniques for CAD-based tissue modelling generation will be described. The latest development in SFF to tissue engineering and a framework of bio-blueprint modelling for three-dimensional cell and organ printing will also be introduced.

  5. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    In the field of environmental engineering, modeling tools are playing an ever larger role in addressing air quality issues, including source pollutant emissions, atmospheric dispersion and human exposure risks. More detailed modeling of environmental flows requires tools for c...

  6. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    In the field of environmental engineering, modeling tools are playing an ever larger role in addressing air quality issues, including source pollutant emissions, atmospheric dispersion and human exposure risks. More detailed modeling of environmental flows requires tools for c...

  7. Precision genome engineering and agriculture: opportunities and regulatory challenges.

    PubMed

    Voytas, Daniel F; Gao, Caixia

    2014-06-01

    Plant agriculture is poised at a technological inflection point. Recent advances in genome engineering make it possible to precisely alter DNA sequences in living cells, providing unprecedented control over a plant's genetic material. Potential future crops derived through genome engineering include those that better withstand pests, that have enhanced nutritional value, and that are able to grow on marginal lands. In many instances, crops with such traits will be created by altering only a few nucleotides among the billions that comprise plant genomes. As such, and with the appropriate regulatory structures in place, crops created through genome engineering might prove to be more acceptable to the public than plants that carry foreign DNA in their genomes. Public perception and the performance of the engineered crop varieties will determine the extent to which this powerful technology contributes towards securing the world's food supply.

  8. The challenges of biomedical engineering education in latin america.

    PubMed

    Monzon, Jorge

    2005-01-01

    The broad scope of Biomedical Engineering requires careful planning when designing educational programs of the discipline, which must prepare students for a successful professional performance in a constantly changing field. Throughout the world, BME education must adapt to the dynamic concept of the profession and its scope. In this paper we present the issues that should be addressed for the successful preparation of future BM engineers in Latin America.

  9. Political science. Reverse-engineering censorship in China: randomized experimentation and participant observation.

    PubMed

    King, Gary; Pan, Jennifer; Roberts, Margaret E

    2014-08-22

    Existing research on the extensive Chinese censorship organization uses observational methods with well-known limitations. We conducted the first large-scale experimental study of censorship by creating accounts on numerous social media sites, randomly submitting different texts, and observing from a worldwide network of computers which texts were censored and which were not. We also supplemented interviews with confidential sources by creating our own social media site, contracting with Chinese firms to install the same censoring technologies as existing sites, and--with their software, documentation, and even customer support--reverse-engineering how it all works. Our results offer rigorous support for the recent hypothesis that criticisms of the state, its leaders, and their policies are published, whereas posts about real-world events with collective action potential are censored. Copyright © 2014, American Association for the Advancement of Science.

  10. Modified high-accuracy 3D shape data conversion system for reverse engineering applications

    NASA Astrophysics Data System (ADS)

    Sitnik, Robert; Kujawinska, Malgorzata

    2001-10-01

    In the paper the sequential steps of reverse engineering based on the data gathered by full-field optical system are discussed. The compete conversion process of a cloud of point coordinates to CAD/CAM is presented. The triangulation algorithm, which automatically creates the triangle mesh from the input cloud of points is described. Each block of this algorithm is explained din details with special attention paid to the parameters controlling the quality of the data conversion process. The adaptive process of reducing the number of the triangles on the base of second derivative of local curvature of objects' surface is explained. The error analysis is discussed at each step of the cloud data processing in dependency of the algorithm initial parameters.

  11. Reverse engineering gene regulatory networks related to quorum sensing in the plant pathogen Pectobacterium atrosepticum.

    PubMed

    Lin, Kuang; Husmeier, Dirk; Dondelinger, Frank; Mayer, Claus D; Liu, Hui; Prichard, Leighton; Salmond, George P C; Toth, Ian K; Birch, Paul R J

    2010-01-01

    The objective of the project reported in the present chapter was the reverse engineering of gene regulatory networks related to quorum sensing in the plant pathogen Pectobacterium atrosepticum from micorarray gene expression profiles, obtained from the wild-type and eight knockout strains. To this end, we have applied various recent methods from multivariate statistics and machine learning: graphical Gaussian models, sparse Bayesian regression, LASSO (least absolute shrinkage and selection operator), Bayesian networks, and nested effects models. We have investigated the degree of similarity between the predictions obtained with the different approaches, and we have assessed the consistency of the reconstructed networks in terms of global topological network properties, based on the node degree distribution. The chapter concludes with a biological evaluation of the predicted network structures.

  12. [Research on point cloud smoothing in knee joint prosthesis modeling based on reverse engineering].

    PubMed

    Zhang, Guoliang; Yao, Jin; Wei, Xing; Pei, Fuxing; Zhou, Zongke

    2008-10-01

    At present, foreign standard knee joint prosthesis is mostly used in clinical practice; it can well represent the biological characteristic of knee joint on human being. So this paper adopts the reverse engineering technology in that connexion, presents novel positioning method of acquiring the point data on the surface of knee joint prosthesis, puts forward the algorithm of three-point angle method for removing the noise error and correcting the noise error based on the least squares plane to smooth point cloud. And then, the surface of knee joint prosthesis with better accuracy and smoothness can be generated. Finally, the knee joint prosthesis model can be generated. Thus, a basis is provided for the localization of knee joint prosthesis. This new algorithm is mainly used for the surface modeling based on point cloud smoothing, including the surface of knee joint prosthesis, the surface of regular shape, and the surface with gentle change in curvature.

  13. Application of Reverse Engineering Template for the Correction of Asymmetric Deformity of Maxillofacial Fibrous Dysplasia.

    PubMed

    Pan, Jianwei; Ye, Bin; Hu, Jing; Li, Xiang; Zhang, Yiqun; Li, Jihua

    2016-03-01

    Facial asymmetry deformity is the most common symptom of patients with fibrous dysplasia. This study provides a novel method based on computed tomography scan data, mirror-imaged reverse engineering and rapid prototyping for design and manufacture of an individual template guiding accurately the extent and quantity of partial resection of hyperplastic tissues to reshape the affected bones during operation. Ten adult patients with unilateral facial fibrous dysplasia accepted these treatments, the postoperative appearances showed that the protrusions were effectively reduced; bilateral faces were basically symmetric with no serious complications. This method shorts operation time, decreases surgical risk, and guarantees the aesthetic symmetry. Apparent recurrence was not observed during the follow-up period, and the final outcomes were satisfactory for both surgeons and patients.

  14. Engineering the oxyanion hole of trypsin for promoting the reverse of proteolysis.

    PubMed

    Franke, Lars; Liebscher, Sandra; Bordusa, Frank

    2014-02-01

    Although proteases are capable of synthesizing peptide bonds via the reverse of proteolysis, they are not proficient at peptide fragment ligation. Further manipulations are needed to shift the native enzyme activity from the cleavage to the synthesis of peptides especially when longer peptides or even proteins are the target molecules of the reaction. This account reports on the synthetic potential of trypsin variants with engineered oxyanion holes mutated by proline mutations, which were designed to minimize proteolytic side reactions during peptide bond synthesis. From the six single and double proline-mutated trypsins, in particular, trypsinQ192P came out as the most promising biocatalyst enabling not only the ligation of cleavage-sensitive peptide fragments but also the selective N-terminal modification of a real protein substrate.

  15. Inferring the Forces Controlling Metaphase Kinetochore Oscillations by Reverse Engineering System Dynamics

    PubMed Central

    McAinsh, Andrew D.; Burroughs, Nigel J.

    2015-01-01

    Kinetochores are multi-protein complexes that mediate the physical coupling of sister chromatids to spindle microtubule bundles (called kinetochore (K)-fibres) from respective poles. These kinetochore-attached K-fibres generate pushing and pulling forces, which combine with polar ejection forces (PEF) and elastic inter-sister chromatin to govern chromosome movements. Classic experiments in meiotic cells using calibrated micro-needles measured an approximate stall force for a chromosome, but methods that allow the systematic determination of forces acting on a kinetochore in living cells are lacking. Here we report the development of mathematical models that can be fitted (reverse engineered) to high-resolution kinetochore tracking data, thereby estimating the model parameters and allowing us to indirectly compute the (relative) force components (K-fibre, spring force and PEF) acting on individual sister kinetochores in vivo. We applied our methodology to thousands of human kinetochore pair trajectories and report distinct signatures in temporal force profiles during directional switches. We found the K-fibre force to be the dominant force throughout oscillations, and the centromeric spring the smallest although it has the strongest directional switching signature. There is also structure throughout the metaphase plate, with a steeper PEF potential well towards the periphery and a concomitant reduction in plate thickness and oscillation amplitude. This data driven reverse engineering approach is sufficiently flexible to allow fitting of more complex mechanistic models; mathematical models of kinetochore dynamics can therefore be thoroughly tested on experimental data for the first time. Future work will now be able to map out how individual proteins contribute to kinetochore-based force generation and sensing. PMID:26618929

  16. Inferring the Forces Controlling Metaphase Kinetochore Oscillations by Reverse Engineering System Dynamics.

    PubMed

    Armond, Jonathan W; Harry, Edward F; McAinsh, Andrew D; Burroughs, Nigel J

    2015-11-01

    Kinetochores are multi-protein complexes that mediate the physical coupling of sister chromatids to spindle microtubule bundles (called kinetochore (K)-fibres) from respective poles. These kinetochore-attached K-fibres generate pushing and pulling forces, which combine with polar ejection forces (PEF) and elastic inter-sister chromatin to govern chromosome movements. Classic experiments in meiotic cells using calibrated micro-needles measured an approximate stall force for a chromosome, but methods that allow the systematic determination of forces acting on a kinetochore in living cells are lacking. Here we report the development of mathematical models that can be fitted (reverse engineered) to high-resolution kinetochore tracking data, thereby estimating the model parameters and allowing us to indirectly compute the (relative) force components (K-fibre, spring force and PEF) acting on individual sister kinetochores in vivo. We applied our methodology to thousands of human kinetochore pair trajectories and report distinct signatures in temporal force profiles during directional switches. We found the K-fibre force to be the dominant force throughout oscillations, and the centromeric spring the smallest although it has the strongest directional switching signature. There is also structure throughout the metaphase plate, with a steeper PEF potential well towards the periphery and a concomitant reduction in plate thickness and oscillation amplitude. This data driven reverse engineering approach is sufficiently flexible to allow fitting of more complex mechanistic models; mathematical models of kinetochore dynamics can therefore be thoroughly tested on experimental data for the first time. Future work will now be able to map out how individual proteins contribute to kinetochore-based force generation and sensing.

  17. The challenges of cellular compartmentalization in plant metabolic engineering.

    PubMed

    Heinig, Uwe; Gutensohn, Michael; Dudareva, Natalia; Aharoni, Asaph

    2013-04-01

    The complex metabolic networks in plants are highly compartmentalized and biochemical steps of a single pathway can take place in multiple subcellular locations. Our knowledge regarding reactions and precursor compounds in the various cellular compartments has increased in recent years due to innovations in tracking the spatial distribution of proteins and metabolites. Nevertheless, to date only few studies have integrated subcellular localization criteria in metabolic engineering attempts. Here, we highlight the crucial factors for subcellular-localization-based strategies in plant metabolic engineering including substrate availability, enzyme targeting, the role of transporters, and multigene transfer approaches. The availability of compartmentalized metabolic network models for plants in the near future will greatly advance the integration of localization constraints in metabolic engineering experiments and aid in predicting their outcomes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Interleukin-6 treatment reverses apoptosis and blunts susceptibility to intraperitoneal bacterial challenge following hemorrhagic shock.

    PubMed

    Arikan, Ayse Akcan; Yu, Bi; Mastrangelo, Mary-Ann; Tweardy, David J

    2006-03-01

    Resuscitation from hemorrhagic shock (HS) predisposes to subsequent infections. Susceptibility to infection following sepsis has been attributed to apoptosis. Interleukin (IL)-6 has been shown to have antiapoptotic properties and to decrease postresuscitation inflammation in rodent and porcine models of HS. The objective was to determine if HS increases host susceptibility to infection, if IL-6 administration at resuscitation reduces this susceptibility, and if changes in susceptibility to infection are accompanied by parallel changes in apoptosis. Mice were randomized into three groups-HS, sham, and no-surgery control-and each group was further randomized to receive either IL-6 (3 microg/kg; HS/IL-6) or placebo (HS/P) at the start of resuscitation. In the HS-infection protocol, each mouse was challenged intraperitoneally the next day with a sublethal dose of Staphylococcus aureus (4x107 colony-forming units); 24 hrs later, the peritoneal cavity was lavaged and the major organs were harvested for culture. In the HS-apoptosis protocol, the livers were harvested the next day and analyzed by means of the terminal deoxynucleotidyl transferase dUTP-biotin nick-end-labeling (TUNEL) assay. HS/P mice had a six- to eight-fold increase in total bacterial counts in comparison with sham and control mice that was attributable to a seven- to nine-fold increase in liver burden. IL-6 treatment reduced total and liver bacterial counts in HS/IL-6 mice by 62% and 69%, respectively, to levels statistically indistinguishable from IL-6-treated sham and control mice. The number of TUNEL-positive liver cells in the HS/P group was increased eight-fold vs. that in the sham group (p=.002); IL-6 resuscitation completely reversed the HS-induced increase in TUNEL-positive cells in the HS/IL-6 group (p=.002). IL-6 treatment at resuscitation eliminated the HS-mediated increase in total and liver bacterial burden and protected the liver from HS-induced apoptosis. Reduced liver apoptosis may

  19. Space Human Factors Engineering Challenges in Long Duration Space Flight

    NASA Technical Reports Server (NTRS)

    Garland, Daniel J.; Endsley, Mica R.; Ellison, June; Caldwell, Barrett S.; Mount, Frances E.; Bond, Robert L. (Technical Monitor)

    1999-01-01

    The focus of this panel is on identifying and discussing the critical human factors challenges facing long duration space flight. Living and working aboard the International Space Station (ISS) will build on the experience humans have had to date aboard the Shuttle and MIR. More extended missions, involving lunar and planetary missions to Mars are being planned. These missions will involve many human factors challenges regarding a number of issues on which more research is needed.

  20. Space Human Factors Engineering Challenges in Long Duration Space Flight

    NASA Technical Reports Server (NTRS)

    Garland, Daniel J.; Endsley, Mica R.; Ellison, June; Caldwell, Barrett S.; Mount, Frances E.; Bond, Robert L. (Technical Monitor)

    1999-01-01

    The focus of this panel is on identifying and discussing the critical human factors challenges facing long duration space flight. Living and working aboard the International Space Station (ISS) will build on the experience humans have had to date aboard the Shuttle and MIR. More extended missions, involving lunar and planetary missions to Mars are being planned. These missions will involve many human factors challenges regarding a number of issues on which more research is needed.

  1. Practical limits for reverse engineering of dynamical systems: a statistical analysis of sensitivity and parameter inferability in systems biology models.

    PubMed

    Erguler, Kamil; Stumpf, Michael P H

    2011-05-01

    The size and complexity of cellular systems make building predictive models an extremely difficult task. In principle dynamical time-course data can be used to elucidate the structure of the underlying molecular mechanisms, but a central and recurring problem is that many and very different models can be fitted to experimental data, especially when the latter are limited and subject to noise. Even given a model, estimating its parameters remains challenging in real-world systems. Here we present a comprehensive analysis of 180 systems biology models, which allows us to classify the parameters with respect to their contribution to the overall dynamical behaviour of the different systems. Our results reveal candidate elements of control in biochemical pathways that differentially contribute to dynamics. We introduce sensitivity profiles that concisely characterize parameter sensitivity and demonstrate how this can be connected to variability in data. Systematically linking data and model sloppiness allows us to extract features of dynamical systems that determine how well parameters can be estimated from time-course measurements, and associates the extent of data required for parameter inference with the model structure, and also with the global dynamical state of the system. The comprehensive analysis of so many systems biology models reaffirms the inability to estimate precisely most model or kinetic parameters as a generic feature of dynamical systems, and provides safe guidelines for performing better inferences and model predictions in the context of reverse engineering of mathematical models for biological systems.

  2. [Engineering by reverse genetics and characterization of the new reassortant influenza virus strain H5N1].

    PubMed

    Zeberezhnyĭ, A D; Grebennikova, T V; Vorkunova, G K; Yuzhakov, A G; Kostina, L V; Norkina, S N; Aliper, T I; Nepoklonov, E A; Lvov, D K

    2014-01-01

    Reverse genetics was applied to engineering of the reassortantvaccine candidate strain against highly pathogenic avian influenza viruses (HPAIVs) of the H5 subtype. The new strain recPR8-H5N1 contains the HA gene from the Russian HPAIV A/Kurgan/05/2005 (H5N1), the NA and internal genes from A/Puerto Rico/8/34 (H1N1). The strain recPR8-H5N1 demonstrated the antigenic specificity (H5), high proliferation rate in 12 days chicken embryos, and was lethal for the embryos in 36 hours. An inactivated emulsified vaccine based on the strain recPR8-H5N1 elicited high antibody titers and protected 6-week-old chickens from lethal challenge with the HPAIV A/Kurgan/05/2005 (H5N1) on day 21 after single immunization. Infection of non-vaccinated birds with the strain recPR8-H5N1 did not cause any pathology, and the virus was not detected using PCR in blood and cloacal swabs on day 7 p.i. Specific weak seroconversion caused by infection with the strain recPR8-H5N1 was detected on day 14 p.i. As a result, a new influenza virus strain was obtained with modified properties.

  3. Public health engineering education in India: current scenario, opportunities and challenges.

    PubMed

    Hussain, Mohammad Akhtar; Sharma, Kavya; Zodpey, Sanjay

    2011-01-01

    Public health engineering can play an important and significant role in solving environmental health issues. In order to confront public health challenges emerging out of environmental problems we need adequately trained public health engineers / environmental engineers. Considering the current burden of disease attributable to environmental factors and expansion in scope of applications of public health / environmental engineering science, it is essential to understand the present scenario of teaching, training and capacity building programs in these areas. Against this background the present research was carried out to know the current teaching and training programs in public health engineering and related disciplines in India and to understand the potential opportunities and challenges available. A systematic, predefined approach was used to collect and assemble the data related to various teaching and training programs in public health engineering / environmental engineering in India. Public health engineering / environmental engineering education and training in the country is mainly offered through engineering institutions, as pre-service and in-service training. Pre-service programs include diploma, degree (graduate) and post-graduate courses affiliated to various state technical boards, institutes and universities, whereas in-service training is mainly provided by Government of India recognized engineering and public health training institutes. Though trainees of these programs acquire skills related to engineering sciences, they significantly lack in public health skills. The teaching and training of public health engineering / environmental engineering is limited as a part of public health programs (MD Community Medicine, MPH, DPH) in India. There is need for developing teaching and training of public health engineering or environmental engineering as an interdisciplinary subject. Public health institutes can play an important and significant role in this

  4. New Challenging Approaches to Engineering Education: Enhancing University-Industry Co-Operation

    ERIC Educational Resources Information Center

    Korhonen-Yrjanheikki, Kati; Tukiainen, Taina; Takala, Minna

    2007-01-01

    Globalization, accelerated time-based competition, qualitative dynamics, rapid development of technology and especially Information and Communications Technology (ICT) developments challenge engineering education and capability development of each engineer. The success and the competitiveness of companies are increasingly based on their employees.…

  5. Ethics in the Engineering Curricula: Topics, Trends and Challenges for the Future.

    ERIC Educational Resources Information Center

    Zandvoort, H.; Van de Poel, I.; Brumsen, M.

    2000-01-01

    Presents a collection of regional papers that give an overview of the present state of ethics teaching in engineering curricula. Provides historical information concerning the motivation for and the development of engineering ethics, points to important topics and trends that arise from the papers, and identifies the main challenges for the…

  6. View of the Flight Readiness Firing (FRF) of the Challengers engines

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Space shuttle orbiter Challenger is given a 20-second test firing of its new main engines on December 18, 1982 on pad 39A at the Kennedy Space Center. This test was the first time these engines ahd been tested in the clustered flight configuration.

  7. New Challenging Approaches to Engineering Education: Enhancing University-Industry Co-Operation

    ERIC Educational Resources Information Center

    Korhonen-Yrjanheikki, Kati; Tukiainen, Taina; Takala, Minna

    2007-01-01

    Globalization, accelerated time-based competition, qualitative dynamics, rapid development of technology and especially Information and Communications Technology (ICT) developments challenge engineering education and capability development of each engineer. The success and the competitiveness of companies are increasingly based on their employees.…

  8. View of the Flight Readiness Firing (FRF) of the Challengers engines

    NASA Image and Video Library

    1983-01-05

    The Space shuttle orbiter Challenger is given a 20-second test firing of its new main engines on December 18, 1982 on pad 39A at the Kennedy Space Center. This test was the first time these engines ahd been tested in the clustered flight configuration.

  9. Promoting Collaborative Problem-Solving Skills in a Course on Engineering Grand Challenges

    ERIC Educational Resources Information Center

    Zou, Tracy X. P.; Mickleborough, Neil C.

    2015-01-01

    The ability to solve problems with people of diverse backgrounds is essential for engineering graduates. A course on engineering grand challenges was designed to promote collaborative problem-solving (CPS) skills. One unique component is that students need to work both within their own team and collaborate with the other team to tackle engineering…

  10. Promoting Collaborative Problem-Solving Skills in a Course on Engineering Grand Challenges

    ERIC Educational Resources Information Center

    Zou, Tracy X. P.; Mickleborough, Neil C.

    2015-01-01

    The ability to solve problems with people of diverse backgrounds is essential for engineering graduates. A course on engineering grand challenges was designed to promote collaborative problem-solving (CPS) skills. One unique component is that students need to work both within their own team and collaborate with the other team to tackle engineering…

  11. Responsible authorship in engineering fields: an overview of current ethical challenges.

    PubMed

    Borenstein, Jason

    2011-06-01

    The primary aim of this article is to identify ethical challenges relating to authorship in engineering fields. Professional organizations and journals do provide crucial guidance in this realm, but this cannot replace the need for frequent and diligent discussions in engineering research communities about what constitutes appropriate authorship practice. Engineering researchers should seek to identify and address issues such as who is entitled to be an author and whether publishing their research could potentially harm the public.

  12. Challenges and opportunities for tissue-engineering polarized epithelium.

    PubMed

    Paz, Ana C; Soleas, John; Poon, James C H; Trieu, Dennis; Waddell, Thomas K; McGuigan, Alison P

    2014-02-01

    The epithelium is one of the most important tissue types in the body and the specific organization of the epithelial cells in these tissues is important for achieving appropriate function. Since many tissues contain an epithelial component, engineering functional epithelium and understanding the factors that control epithelial maturation and organization are important for generating whole artificial organ replacements. Furthermore, disruption of the cellular organization leads to tissue malfunction and disease; therefore, engineered epithelium could provide a valuable in vitro model to study disease phenotypes. Despite the importance of epithelial tissues, a surprisingly limited amount of effort has been focused on organizing epithelial cells into artificial polarized epithelium with an appropriate structure that resembles that seen in vivo. In this review, we provide an overview of epithelial tissue organization and highlight the importance of cell polarization to achieve appropriate epithelium function. We next describe the in vitro models that exist to create polarized epithelium and summarize attempts to engineer artificial epithelium for clinical use. Finally, we highlight the opportunities that exist to translate strategies from tissue engineering other tissues to generate polarized epithelium with a functional structure.

  13. Are women engineers in Lebanon prepared for the challenges of an engineering profession?

    NASA Astrophysics Data System (ADS)

    Baytiyeh, Hoda

    2013-08-01

    This study investigates the status of women engineers in the Middle East, considering women engineers in Lebanon as a case study. The author investigated the following questions: What are the influences behind females' decisions to choose engineering as their major course of study? What are the motives behind this decision? What are the perceptions of females regarding the essential skills for a successful engineering career? An online survey consisting of Likert-scale items was completed by 327 female engineers who graduated from universities in Lebanon and now work in various locations around the world. A genuine interest in the field appeared to be the main influence in the participants' decisions to choose engineering profession. The potential for professional growth was the leading motivator for choosing engineering. Although participants reported that they possessed adequate theoretical knowledge and technical skills before graduation, in the actual practice of engineering, they noted weaknesses in creativity and innovation.

  14. Challenger

    ERIC Educational Resources Information Center

    Allday, Jonathan

    2002-01-01

    The events that led to the spectacular destruction of the Space Shuttle "Challenger" in 1986 are detailed here. They show how NASA should have heeded engineers' worries over materials problems resulting from a launch in cold weather. Suggestions are made of how pupils could also learn from this tragedy. (Contains 4 figures and 2 footnotes.)

  15. Challenger

    ERIC Educational Resources Information Center

    Allday, Jonathan

    2002-01-01

    The events that led to the spectacular destruction of the Space Shuttle "Challenger" in 1986 are detailed here. They show how NASA should have heeded engineers' worries over materials problems resulting from a launch in cold weather. Suggestions are made of how pupils could also learn from this tragedy. (Contains 4 figures and 2 footnotes.)

  16. Mitigation of reversible self-association and viscosity in a human IgG1 monoclonal antibody by rational, structure-guided Fv engineering

    PubMed Central

    Geoghegan, James C.; Fleming, Ryan; Damschroder, Melissa; Bishop, Steven M.; Sathish, Hasige A.; Esfandiary, Reza

    2016-01-01

    ABSTRACT Undesired solution behaviors such as reversible self-association (RSA), high viscosity, and liquid-liquid phase separation can introduce substantial challenges during development of monoclonal antibody formulations. Although a global mechanistic understanding of RSA (i.e., native and reversible protein-protein interactions) is sufficient to develop robust formulation controls, its mitigation via protein engineering requires knowledge of the sites of protein-protein interactions. In the study reported here, we coupled our previous hydrogen-deuterium exchange mass spectrometry findings with structural modeling and in vitro screening to identify the residues responsible for RSA of a model IgG1 monoclonal antibody (mAb-C), and rationally engineered variants with improved solution properties (i.e., reduced RSA and viscosity). Our data show that mutation of either solvent-exposed aromatic residues within the heavy and light chain variable regions or buried residues within the heavy chain/light chain interface can significantly mitigate RSA and viscosity by reducing the IgG's surface hydrophobicity. The engineering strategy described here highlights the utility of integrating complementary experimental and in silico methods to identify mutations that can improve developability, in particular, high concentration solution properties, of candidate therapeutic antibodies. PMID:27050875

  17. Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities

    NASA Technical Reports Server (NTRS)

    Leavitt, L. D.; Burley, J. R., II

    1985-01-01

    An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0.

  18. An Application of Reverse Engineering to Automatic Item Generation: A Proof of Concept Using Automatically Generated Figures

    ERIC Educational Resources Information Center

    Lorié, William A.

    2013-01-01

    A reverse engineering approach to automatic item generation (AIG) was applied to a figure-based publicly released test item from the Organisation for Economic Cooperation and Development (OECD) Programme for International Student Assessment (PISA) mathematical literacy cognitive instrument as part of a proof of concept. The author created an item…

  19. [DEVELOPMENT AND CHALLENGES OF ANNULUS FIBROSUS TISSUE ENGINEERING].

    PubMed

    Li, Xiaolong; Kong, Qingquan

    2015-04-01

    To review the biomaterial and clinical prospects of annulus tibrosus tissue engineering. The recent literature concerning annulus fibrosus tissue engineering, including cell source, bioactive molecules, and biomaterial was extensively reviewed and summarized. Mesenchymal stem cells (MSCs) is an ideal seed cells. When annulus fibrosus cells and MSCs in the ratio of 2:1 are cultured, it shows the closest mRNA expression levels of annulus fibrosus-related markers. Bioactive molecules can be divided into 4 types: growth factors, morphogens, catabolic enzyme inhibitors, and intracellular regulators. They play an active role in promoting the synthesis of extracellular matrix, and maintaining intervertebral disc homeostasis and a balance between anabolic- and catabolic process in the disc. Based on the source, biological materials can be divided into natural materials, synthetic materials, and composite materials. The mechanical properties of the annulus fibrosus is an important basis for material design. Up to now, none of these scaffold materials is accepted as the most suitable one. The selection of scaffold materials is still to be further studied. The development of novel composite biomaterials is a trend. The annulus fibrosus tissue engineering for the anulus fibrosus regeneration and repair will bring very broad prospects for clinical application in future.

  20. Challenges in Learning Communication Skills in Chemical Engineering.

    ERIC Educational Resources Information Center

    Dannels, Deanna P.; Anson, Chris M.; Bullard, Lisa; Peretti, Steven

    2003-01-01

    Notes that communication across the curriculum initiatives face multiple curricular and pedagogical challenges that are especially appropriate for investigation within a scholarship of teaching and learning framework. Examines technical classes that emphasize speaking and writing. Indicates that students were resistant toward the incursion of…

  1. Engineered Nanoscale Materials and Derivative Products: Regulatory Challenges

    DTIC Science & Technology

    2008-01-22

    to microbes, and some product manufacturers have made antibacterial claims for their products containing nanosilver . In addition, research has...intent to regulate nanosilver under FIFRA when it is released from certain washing machines and other products for which manufacturers claim...nanomaterials, including nanosilver , under certain conditions. To address this challenge, EPA’s Science Policy Council, an internal policy group, formed

  2. Grand challenge commentary: Synthetic immunology to engineer human immunity.

    PubMed

    Spiegel, David A

    2010-12-01

    Rationally designing new strategies to control the human immune response stands as a key challenge for the scientific community. Chemical biologists have the opportunity to address specific issues in this area that have important implications for both basic science and clinical medicine.

  3. Development of Cryogenic Engine for GSLV MkIII: Technological Challenges

    NASA Astrophysics Data System (ADS)

    Praveen, RS; Jayan, N.; Bijukumar, KS; Jayaprakash, J.; Narayanan, V.; Ayyappan, G.

    2017-02-01

    Cryogenic engine capable of delivering 200 kN thrust is being developed for the first time in the country by ISRO for powering the upper stage of GSLV Mk-III, the next generation launch vehicle of ISRO capable of launching four tonne class satellites to Geo-synchronous Transfer Orbit(GTO). Development of this engine started a decade ago when various sub-systems development and testing were taken up. Starting with injector element development, the design, realization and testing of the major sub-systems viz the gas generator, turbopumps, start-up system and thrust chamber have been successfully done in a phased manner before conducting a series of developmental tests in the integrated engine mode. Apart from the major sub-systems, many critical components like the igniter, control components etc were independently developed and qualified. During the development program many challenges were faced in almost all areas of propulsion engineering. Systems engineering of the engine was another key challenge in the realization. This paper gives an outlook on various technological challenges faced in the key areas related to the engine development, insight to the solutions and measures taken to overcome the challenges.

  4. Status, Vision, and Challenges of an Intelligent Distributed Engine Control Architecture

    NASA Technical Reports Server (NTRS)

    Behbahani, Alireza; Culley, Dennis; Garg, Sanjay; Millar, Richard; Smith, Bert; Wood, Jim; Mahoney, Tim; Quinn, Ronald; Carpenter, Sheldon; Mailander, Bill; Battestin, Gary; Roney, Walter; Bluish, Colin; Rhoden, William; Storey, Bill

    2007-01-01

    A Distributed Engine Control Working Group (DECWG) consisting of the Department of Defense (DoD), the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) and industry has been formed to examine the current and future requirements of propulsion engine systems. The scope of this study will include an assessment of the paradigm shift from centralized engine control architecture to an architecture based on distributed control utilizing open system standards. Included will be a description of the work begun in the 1990's, which continues today, followed by the identification of the remaining technical challenges which present barriers to on-engine distributed control.

  5. Automation of reverse engineering process in aircraft modeling and related optimization problems

    NASA Technical Reports Server (NTRS)

    Li, W.; Swetits, J.

    1994-01-01

    During the year of 1994, the engineering problems in aircraft modeling were studied. The initial concern was to obtain a surface model with desirable geometric characteristics. Much of the effort during the first half of the year was to find an efficient way of solving a computationally difficult optimization model. Since the smoothing technique in the proposal 'Surface Modeling and Optimization Studies of Aerodynamic Configurations' requires solutions of a sequence of large-scale quadratic programming problems, it is important to design algorithms that can solve each quadratic program in a few interactions. This research led to three papers by Dr. W. Li, which were submitted to SIAM Journal on Optimization and Mathematical Programming. Two of these papers have been accepted for publication. Even though significant progress has been made during this phase of research and computation times was reduced from 30 min. to 2 min. for a sample problem, it was not good enough for on-line processing of digitized data points. After discussion with Dr. Robert E. Smith Jr., it was decided not to enforce shape constraints in order in order to simplify the model. As a consequence, P. Dierckx's nonparametric spline fitting approach was adopted, where one has only one control parameter for the fitting process - the error tolerance. At the same time the surface modeling software developed by Imageware was tested. Research indicated a substantially improved fitting of digitalized data points can be achieved if a proper parameterization of the spline surface is chosen. A winning strategy is to incorporate Dierckx's surface fitting with a natural parameterization for aircraft parts. The report consists of 4 chapters. Chapter 1 provides an overview of reverse engineering related to aircraft modeling and some preliminary findings of the effort in the second half of the year. Chapters 2-4 are the research results by Dr. W. Li on penalty functions and conjugate gradient methods for

  6. Wright St Univ Participation in AFRL University Engineering Design Challenge

    DTIC Science & Technology

    2014-12-23

    capstone sequence through the end of the year. Depending on the nature of the objectives of the competition , the team members were chosen depending on...advisor to provide the current project status, and to plan the following week’s objectives. Student Design Challenge Competition U U U SAR Scott K...the vehicle utilizing four-wheels also successfully ascended a testing wall. All three designs will be presented at the competition in order to ensure

  7. Sexing a sex-role-reversed species based on plumage: potential challenges in the red phalarope.

    PubMed

    Giroux, Marie-Andrée; Ditlecadet, Delphine; Martin, Luc J; Lanctot, Richard B; Lecomte, Nicolas

    2016-01-01

    Sex-role reversal, in which males care for offspring, can occur when mate competition is stronger between females than males. Secondary sex traits and mate attracting displays in sex-role-reversed species are usually more pronounced in females than in males. The red phalarope (Phalaropus fulicarius) is a textbook example of a sex-role-reversed species. It is generally agreed that males are responsible for all incubation and parental care duties, whereas females typically desert males after having completed a clutch and may pair with new males to lay additional clutches. The breeding plumage of female red phalaropes is usually more brightly colored than male plumage, a reversed sexual dichromatism usually associated with sex-role reversal. Here, we confirm with PCR-based sexing that male red phalaropes can exhibit both the red body plumage typical of a female and the incubation behavior typical of a male. Our result, combined with previous observations of brightly colored red phalaropes incubating nests at the same arctic location (Igloolik Island, Nunavut, Canada), suggests that plumage dichromatism alone may not be sufficient to distinguish males from females in this breeding population of red phalaropes. This stresses the need for more systematic genetic sexing combined with standardized description of intersexual differences in red phalarope plumages. Determining whether such female-like plumage on males is a result of phenotypic plasticity or genetic variation could contribute to further understanding sex-role reversal strategies in the short Arctic summer.

  8. Sexing a sex-role-reversed species based on plumage: potential challenges in the red phalarope

    PubMed Central

    Ditlecadet, Delphine; Martin, Luc J.; Lanctot, Richard B.; Lecomte, Nicolas

    2016-01-01

    Sex-role reversal, in which males care for offspring, can occur when mate competition is stronger between females than males. Secondary sex traits and mate attracting displays in sex-role-reversed species are usually more pronounced in females than in males. The red phalarope (Phalaropus fulicarius) is a textbook example of a sex-role-reversed species. It is generally agreed that males are responsible for all incubation and parental care duties, whereas females typically desert males after having completed a clutch and may pair with new males to lay additional clutches. The breeding plumage of female red phalaropes is usually more brightly colored than male plumage, a reversed sexual dichromatism usually associated with sex-role reversal. Here, we confirm with PCR-based sexing that male red phalaropes can exhibit both the red body plumage typical of a female and the incubation behavior typical of a male. Our result, combined with previous observations of brightly colored red phalaropes incubating nests at the same arctic location (Igloolik Island, Nunavut, Canada), suggests that plumage dichromatism alone may not be sufficient to distinguish males from females in this breeding population of red phalaropes. This stresses the need for more systematic genetic sexing combined with standardized description of intersexual differences in red phalarope plumages. Determining whether such female-like plumage on males is a result of phenotypic plasticity or genetic variation could contribute to further understanding sex-role reversal strategies in the short Arctic summer. PMID:27168992

  9. Reverse engineering of Ayurvedic lipid based formulation, ghrita by combined column chromatography, normal and reverse phase HPTLC analysis.

    PubMed

    Duraipandi, Selvakumar; Selvakumar, Vijaya; Er, Ng Yun

    2015-03-13

    Ghritas are ayurvedic lipid based preparations in which oil or ghee is boiled with prescribed kasaya (polyherbal decoction) and kalka (fine paste of herbs) until the evaporation of aqueous phase transfers the contents into oily phase. The polyherbal decoction used in the preparation predominantly contains water soluble Active Botanical Ingredients (ABIs). The column chromatography was used to fractionate the ghrita into polar and non-polar fractions on silica gel as adsorbent using petroleum ether and mixture of ethanol, methanol & water as eluents. These fractions were further analysed by normal and reverse phase HPTLC analysis for the presence of the contents and its polarity. The results showed that all the ABIs present in the formulation were polar since the fractionated non-polar fraction did not show the presence of any active botanical ingredients on normal and reverse phase HPTLC analysis. The ayurvedic system of medicine has got its own technique of incorporating the polar contents into a lipid base for enhanced absorption and delivery of the ABIs at targets.

  10. Technology Challenges for Deep-Throttle Cryogenic Engines for Space Exploration

    NASA Astrophysics Data System (ADS)

    Brown, Kendall K.; Nelson, Karl W.

    2005-02-01

    Historically, cryogenic rocket engines have not been used for in-space applications due to their additional complexity, the mission need for high reliability, and the challenges of propellant boil-off. While the mission and vehicle architectures are not yet defined for the lunar and Martian robotic and human exploration objectives, cryogenic rocket engines offer the potential for higher performance and greater architecture/mission flexibility. In-situ cryogenic propellant production could enable a more robust exploration program by significantly reducing the propellant mass delivered to low earth orbit, thus warranting the evaluation of cryogenic rocket engines versus the hypergolic bipropellant engines used in the Apollo program. A multi-use engine, one which can provide the functionality that separate engines provided in the Apollo mission architecture, is desirable for lunar and Mars exploration missions because it increases overall architecture effectiveness through commonality and modularity. The engine requirement derivation process must address each unique mission application and each unique phase within each mission. The resulting requirements, such as thrust level, performance, packaging, burn duration, number of operations; required impulses for each trajectory phase; operation after extended space or surface exposure; availability for inspection and maintenance; throttle range for planetary descent, ascent, acceleration limits and many more must be addressed. Within engine system studies, the system and component technology, capability, and risks must be evaluated and a balance between the appropriate amount of technology-push and technology-pull must be addressed. This paper will summarize many of the key technology challenges associated with using high-performance cryogenic liquid propellant rocket engine systems and components in the exploration program architectures. The paper is divided into two areas. The first area describes how the mission

  11. Technology Challenges for Deep-Throttle Cryogenic Engines for Space Exploration

    NASA Technical Reports Server (NTRS)

    Brown, Kendall K.; Nelson, Karl W.

    2005-01-01

    Historically, cryogenic rocket engines have not been used for in-space applications due to their additional complexity, the mission need for high reliability, and the challenges of propellant boil-off. While the mission and vehicle architectures are not yet defined for the lunar and Martian robotic and human exploration objectives, cryogenic rocket engines offer the potential for higher performance and greater architecture/mission flexibility. In-situ cryogenic propellant production could enable a more robust exploration program by significantly reducing the propellant mass delivered to low earth orbit, thus warranting the evaluation of cryogenic rocket engines versus the hypergolic bi-propellant engines used in the Apollo program. A multi-use engine. one which can provide the functionality that separate engines provided in the Apollo mission architecture, is desirable for lunar and Mars exploration missions because it increases overall architecture effectiveness through commonality and modularity. The engine requirement derivation process must address each unique mission application and each unique phase within each mission. The resulting requirements, such as thrust level, performance, packaging, bum duration, number of operations; required impulses for each trajectory phase; operation after extended space or surface exposure; availability for inspection and maintenance; throttle range for planetary descent, ascent, acceleration limits and many more must be addressed. Within engine system studies, the system and component technology, capability, and risks must be evaluated and a balance between the appropriate amount of technology-push and technology-pull must be addressed. This paper will summarize many of the key technology challenges associated with using high-performance cryogenic liquid propellant rocket engine systems and components in the exploration program architectures. The paper is divided into two areas. The first area describes how the mission

  12. Tissue engineering and regenerative medicine: history, progress, and challenges.

    PubMed

    Berthiaume, François; Maguire, Timothy J; Yarmush, Martin L

    2011-01-01

    The past three decades have seen the emergence of an endeavor called tissue engineering and regenerative medicine in which scientists, engineers, and physicians apply tools from a variety of fields to construct biological substitutes that can mimic tissues for diagnostic and research purposes and can replace (or help regenerate) diseased and injured tissues. A significant portion of this effort has been translated to actual therapies, especially in the areas of skin replacement and, to a lesser extent, cartilage repair. A good amount of thoughtful work has also yielded prototypes of other tissue substitutes such as nerve conduits, blood vessels, liver, and even heart. Forward movement to clinical product, however, has been slow. Another offshoot of these efforts has been the incorporation of some new exciting technologies (e.g., microfabrication, 3D printing) that may enable future breakthroughs. In this review we highlight the modest beginnings of the field and then describe three application examples that are in various stages of development, ranging from relatively mature (skin) to ongoing proof-of-concept (cartilage) to early stage (liver). We then discuss some of the major issues that limit the development of complex tissues, some of which are fundamentals-based, whereas others stem from the needs of the end users.

  13. How to Overcome Numerical Challenges to Modeling Stirling Engines

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger W.; Wilson, Scott D.; Tew, Roy C.

    2004-01-01

    Nuclear thermal to electric power conversion carries the promise of longer duration missions and higher scientific data transmission rates back to Earth for a range of missions, including both Mars rovers and deep space missions. A free-piston Stirling convertor is a candidate technology that is considered an efficient and reliable power conversion device for such purposes. While already very efficient, it is believed that better Stirling engines can be developed if the losses inherent in current designs could be better understood. However, they are difficult to instrument and so efforts are underway to simulate a complete Stirling engine numerically. This has only recently been attempted and a review of the methods leading up to and including such computational analysis is presented. And finally it is proposed that the quality and depth of Stirling loss understanding may be improved by utilizing the higher fidelity and efficiency of recently developed numerical methods. One such method, the Ultra HI-FI technique is presented in detail.

  14. A Data-Driven Approach to Reverse Engineering Customer Engagement Models: Towards Functional Constructs

    PubMed Central

    de Vries, Natalie Jane; Carlson, Jamie; Moscato, Pablo

    2014-01-01

    Online consumer behavior in general and online customer engagement with brands in particular, has become a major focus of research activity fuelled by the exponential increase of interactive functions of the internet and social media platforms and applications. Current research in this area is mostly hypothesis-driven and much debate about the concept of Customer Engagement and its related constructs remains existent in the literature. In this paper, we aim to propose a novel methodology for reverse engineering a consumer behavior model for online customer engagement, based on a computational and data-driven perspective. This methodology could be generalized and prove useful for future research in the fields of consumer behaviors using questionnaire data or studies investigating other types of human behaviors. The method we propose contains five main stages; symbolic regression analysis, graph building, community detection, evaluation of results and finally, investigation of directed cycles and common feedback loops. The ‘communities’ of questionnaire items that emerge from our community detection method form possible ‘functional constructs’ inferred from data rather than assumed from literature and theory. Our results show consistent partitioning of questionnaire items into such ‘functional constructs’ suggesting the method proposed here could be adopted as a new data-driven way of human behavior modeling. PMID:25036766

  15. Modeling of multisensory convergence with a network of spiking neurons: a reverse engineering approach.

    PubMed

    Lim, Hun Ki; Keniston, Leslie P; Cios, Krzysztof J

    2011-07-01

    Multisensory processing in the brain underlies a wide variety of perceptual phenomena, but little is known about the underlying mechanisms of how multisensory neurons are formed. This lack of knowledge is due to the difficulty for biological experiments to manipulate and test the parameters of multisensory convergence, the first and definitive step in the multisensory process. Therefore, by using a computational model of multisensory convergence, this study seeks to provide insight into the mechanisms of multisensory convergence. To reverse-engineer multisensory convergence, we used a biologically realistic neuron model and a biology-inspired plasticity rule, but did not make any a priori assumptions about multisensory properties of neurons in the network. The network consisted of two separate projection areas that converged upon neurons in a third area, and stimulation involved activation of one of the projection areas (or the other) or their combination. Experiments consisted of two parts: network training and multisensory simulation. Analyses were performed, first, to find multisensory properties in the simulated networks; second, to reveal properties of the network using graph theoretical approach; and third, to generate hypothesis related to the multisensory convergence. The results showed that the generation of multisensory neurons related to the topological properties of the network, in particular, the strengths of connections after training, was found to play an important role in forming and thus distinguishing multisensory neuron types.

  16. A data-driven approach to reverse engineering customer engagement models: towards functional constructs.

    PubMed

    de Vries, Natalie Jane; Carlson, Jamie; Moscato, Pablo

    2014-01-01

    Online consumer behavior in general and online customer engagement with brands in particular, has become a major focus of research activity fuelled by the exponential increase of interactive functions of the internet and social media platforms and applications. Current research in this area is mostly hypothesis-driven and much debate about the concept of Customer Engagement and its related constructs remains existent in the literature. In this paper, we aim to propose a novel methodology for reverse engineering a consumer behavior model for online customer engagement, based on a computational and data-driven perspective. This methodology could be generalized and prove useful for future research in the fields of consumer behaviors using questionnaire data or studies investigating other types of human behaviors. The method we propose contains five main stages; symbolic regression analysis, graph building, community detection, evaluation of results and finally, investigation of directed cycles and common feedback loops. The 'communities' of questionnaire items that emerge from our community detection method form possible 'functional constructs' inferred from data rather than assumed from literature and theory. Our results show consistent partitioning of questionnaire items into such 'functional constructs' suggesting the method proposed here could be adopted as a new data-driven way of human behavior modeling.

  17. Genetic Network Inference: From Co-Expression Clustering to Reverse Engineering

    NASA Technical Reports Server (NTRS)

    Dhaeseleer, Patrik; Liang, Shoudan; Somogyi, Roland

    2000-01-01

    Advances in molecular biological, analytical, and computational technologies are enabling us to systematically investigate the complex molecular processes underlying biological systems. In particular, using high-throughput gene expression assays, we are able to measure the output of the gene regulatory network. We aim here to review datamining and modeling approaches for conceptualizing and unraveling the functional relationships implicit in these datasets. Clustering of co-expression profiles allows us to infer shared regulatory inputs and functional pathways. We discuss various aspects of clustering, ranging from distance measures to clustering algorithms and multiple-duster memberships. More advanced analysis aims to infer causal connections between genes directly, i.e., who is regulating whom and how. We discuss several approaches to the problem of reverse engineering of genetic networks, from discrete Boolean networks, to continuous linear and non-linear models. We conclude that the combination of predictive modeling with systematic experimental verification will be required to gain a deeper insight into living organisms, therapeutic targeting, and bioengineering.

  18. Reveal, A General Reverse Engineering Algorithm for Inference of Genetic Network Architectures

    NASA Technical Reports Server (NTRS)

    Liang, Shoudan; Fuhrman, Stefanie; Somogyi, Roland

    1998-01-01

    Given the immanent gene expression mapping covering whole genomes during development, health and disease, we seek computational methods to maximize functional inference from such large data sets. Is it possible, in principle, to completely infer a complex regulatory network architecture from input/output patterns of its variables? We investigated this possibility using binary models of genetic networks. Trajectories, or state transition tables of Boolean nets, resemble time series of gene expression. By systematically analyzing the mutual information between input states and output states, one is able to infer the sets of input elements controlling each element or gene in the network. This process is unequivocal and exact for complete state transition tables. We implemented this REVerse Engineering ALgorithm (REVEAL) in a C program, and found the problem to be tractable within the conditions tested so far. For n = 50 (elements) and k = 3 (inputs per element), the analysis of incomplete state transition tables (100 state transition pairs out of a possible 10(exp 15)) reliably produced the original rule and wiring sets. While this study is limited to synchronous Boolean networks, the algorithm is generalizable to include multi-state models, essentially allowing direct application to realistic biological data sets. The ability to adequately solve the inverse problem may enable in-depth analysis of complex dynamic systems in biology and other fields.

  19. Reconstructing 3D CAD models for simulation using imaging-based reverse engineering

    NASA Astrophysics Data System (ADS)

    Voisin, Sophie; Page, David; Koschan, Andreas; Abidi, Mongi

    2006-05-01

    The purpose of this research is to investigate imaging-based methods to reconstruct 3D CAD models of real-world objects. The methodology uses structured lighting technologies such as coded-pattern projection and laser-based triangulation to sample 3D points on the surfaces of objects and then to reconstruct these surfaces from the dense point samples. This reverse engineering (RE) research presents reconstruction results for a military tire that is important to tire-soil simulations. The limitations of this approach are the current level of accuracy that imaging-based systems offer relative to more traditional CMM modeling systems. The benefit however is the potential for denser point samples and increased scanning speeds of objects, and with time, the imaging technologies should continue to improve to compete with CMM accuracy. This approach to RE should lead to high fidelity models of manufactured and prototyped components for comparison to the original CAD models and for simulation analysis. We focus this paper on the data collection and view registration problems within the RE pipeline.

  20. A Critical Analysis of a Hand Orthosis Reverse Engineering and 3D Printing Process

    PubMed Central

    2016-01-01

    The possibility to realize highly customized orthoses is receiving boost thanks to the widespread diffusion of low-cost 3D printing technologies. However, rapid prototyping (RP) with 3D printers is only the final stage of patient personalized orthotics processes. A reverse engineering (RE) process is in fact essential before RP, to digitize the 3D anatomy of interest and to process the obtained surface with suitable modeling software, in order to produce the virtual solid model of the orthosis to be printed. In this paper, we focus on the specific and demanding case of the customized production of hand orthosis. We design and test the essential steps of the entire production process with particular emphasis on the accurate acquisition of the forearm geometry and on the subsequent production of a printable model of the orthosis. The choice of the various hardware and software tools (3D scanner, modeling software, and FDM printer) is aimed at the mitigation of the design and production costs while guaranteeing suitable levels of data accuracy, process efficiency, and design versatility. Eventually, the proposed method is critically analyzed so that the residual issues and critical aspects are highlighted in order to discuss possible alternative approaches and to derive insightful observations that could guide future research activities. PMID:27594781

  1. Reverse engineering nuclear properties from rare earth abundances in the r process

    NASA Astrophysics Data System (ADS)

    Mumpower, M. R.; McLaughlin, G. C.; Surman, R.; Steiner, A. W.

    2017-03-01

    The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or r process of nucleosynthesis. The solar r-process residuals show a small peak in the rare earths around A∼ 160, which is proposed to be formed dynamically during the end phase of the r process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main r process. We explore the formation of the rare earth peak from the perspective of an inverse problem, using Monte Carlo studies of nuclear masses to investigate the unknown nuclear properties required to best match rare earth abundance sector of the solar isotopic residuals. When nuclear masses are changed, we recalculate the relevant β-decay properties and neutron capture rates in the rare earth region. The feedback provided by this observational constraint allows for the reverse engineering of nuclear properties far from stability where no experimental information exists. We investigate a range of astrophysical conditions with this method and show how these lead to different predictions in the nuclear properties influential to the formation of the rare earth peak. We conclude that targeted experimental campaigns in this region will help to resolve the type of conditions responsible for the production of the rare earth nuclei, and will provide new insights into the longstanding problem of the astrophysical site(s) of the r process.

  2. Paraquat-Melanin Redox-Cycling: Evidence from Electrochemical Reverse Engineering.

    PubMed

    Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; Panzella, Lucia; Alfieri, Maria Laura; Napolitano, Alessandra; Bentley, William E; Payne, Gregory F

    2016-08-17

    Parkinson's disease is a neurodegenerative disorder associated with oxidative stress and the death of melanin-containing neurons of the substantia nigra. Epidemiological evidence links exposure to the pesticide paraquat (PQ) to Parkinson's disease, and this link has been explained by a redox cycling mechanism that induces oxidative stress. Here, we used a novel electrochemistry-based reverse engineering methodology to test the hypothesis that PQ can undergo reductive redox cycling with melanin. In this method, (i) an insoluble natural melanin (from Sepia melanin) and a synthetic model melanin (having a cysteinyldopamine-melanin core and dopamine-melanin shell) were entrapped in a nonconducting hydrogel film adjacent to an electrode, (ii) the film-coated electrode was immersed in solutions containing PQ (putative redox cycling reductant) and a redox cycling oxidant (ferrocene dimethanol), (iii) sequences of input potentials (i.e., voltages) were imposed to the underlying electrode to systematically engage reductive and oxidative redox cycling, and (iv) output response currents were analyzed for signatures of redox cycling. The response characteristics of the PQ-melanin systems to various input potential sequences support the hypothesis that PQ can directly donate electrons to melanin. This observation of PQ-melanin redox interactions demonstrates an association between two components that have been individually linked to oxidative stress and Parkinson's disease. Potentially, melanin's redox activity could be an important component in understanding the etiology of neurological disorders such as Parkinson's disease.

  3. Minimum network constraint on reverse engineering to develop biological regulatory networks.

    PubMed

    Shao, Bin; Wu, Jiayi; Tian, Binghui; Ouyang, Qi

    2015-09-07

    Reconstructing the topological structure of biological regulatory networks from microarray expression data or data of protein expression profiles is one of major tasks in systems biology. In recent years, various mathematical methods have been developed to meet this task. Here, based on our previously reported reverse engineering method, we propose a new constraint, i.e., the minimum network constraint, to facilitate the reconstruction of biological networks. Three well studied regulatory networks (the budding yeast cell cycle network, the fission yeast cell cycle network, and the SOS network of Escherichia coli) were used as the test sets to verify the performance of this method. Numerical results show that the biological networks prefer to use the minimal networks to fulfill their functional tasks, making it possible to apply minimal network criteria in the network reconstruction process. Two scenarios were considered in the reconstruction process: generating data using different initial conditions; and generating data from knock out and over-expression experiments. In both cases, network structures are revealed faithfully in a few steps using our approach.

  4. Reverse engineering of gene regulatory networks based on S-systems and Bat algorithm.

    PubMed

    Mandal, Sudip; Khan, Abhinandan; Saha, Goutam; Pal, Rajat Kumar

    2016-06-01

    The correct inference of gene regulatory networks for the understanding of the intricacies of the complex biological regulations remains an intriguing task for researchers. With the availability of large dimensional microarray data, relationships among thousands of genes can be simultaneously extracted. Among the prevalent models of reverse engineering genetic networks, S-system is considered to be an efficient mathematical tool. In this paper, Bat algorithm, based on the echolocation of bats, has been used to optimize the S-system model parameters. A decoupled S-system has been implemented to reduce the complexity of the algorithm. Initially, the proposed method has been successfully tested on an artificial network with and without the presence of noise. Based on the fact that a real-life genetic network is sparsely connected, a novel Accumulative Cardinality based decoupled S-system has been proposed. The cardinality has been varied from zero up to a maximum value, and this model has been implemented for the reconstruction of the DNA SOS repair network of Escherichia coli. The obtained results have shown significant improvements in the detection of a greater number of true regulations, and in the minimization of false detections compared to other existing methods.

  5. Using reverse engineering and computational fluid dynamics to investigate a lower arm amputee swimmer's performance.

    PubMed

    Lecrivain, Gregory; Slaouti, Arezki; Payton, Carl; Kennedy, Ian

    2008-09-18

    In front crawl swimming, the hand and the corresponding forearm generate major propulsive forces. Such forces have been studied largely through experimental tests and more recently through the use of steady computational fluid dynamics (CFD). However, the effect of the upper arm on the propulsive forces has generally not been taken into consideration. An understanding of such forces is fundamental for the performance of swimmers who have an arm amputation at the level of the elbow. This study introduces the great potential offered by the multidisciplinary approach combining reverse engineering and unsteady CFD in a novel dynamic and interactive way. A complex CFD mesh model, representing the swimmer body and its upper arm, is produced. The model, including the arm rotation and a body roll movement, interacts dynamically with the fluid flow. Forces generated by the upper arm can then be investigated in great detail. In this particular study, it is found that the upper arm effectively contributes to the propulsion of the body. The propulsive force was numerically computed throughout the pull and reaches maxima of 8 N. Results obtained in this study could be extended in a similar way to any other limb movement within a fluid flow.

  6. A Critical Analysis of a Hand Orthosis Reverse Engineering and 3D Printing Process.

    PubMed

    Baronio, Gabriele; Harran, Sami; Signoroni, Alberto

    2016-01-01

    The possibility to realize highly customized orthoses is receiving boost thanks to the widespread diffusion of low-cost 3D printing technologies. However, rapid prototyping (RP) with 3D printers is only the final stage of patient personalized orthotics processes. A reverse engineering (RE) process is in fact essential before RP, to digitize the 3D anatomy of interest and to process the obtained surface with suitable modeling software, in order to produce the virtual solid model of the orthosis to be printed. In this paper, we focus on the specific and demanding case of the customized production of hand orthosis. We design and test the essential steps of the entire production process with particular emphasis on the accurate acquisition of the forearm geometry and on the subsequent production of a printable model of the orthosis. The choice of the various hardware and software tools (3D scanner, modeling software, and FDM printer) is aimed at the mitigation of the design and production costs while guaranteeing suitable levels of data accuracy, process efficiency, and design versatility. Eventually, the proposed method is critically analyzed so that the residual issues and critical aspects are highlighted in order to discuss possible alternative approaches and to derive insightful observations that could guide future research activities.

  7. Reverse engineering liver buds through self-driven condensation and organization towards medical application.

    PubMed

    Shinozawa, Tadahiro; Yoshikawa, Hiroshi Y; Takebe, Takanori

    2016-12-15

    The self-organizing tissue-based approach coupled with induced pluripotent stem (iPS) cell technology is evolving as a promising field for designing organoids in culture and is expected to achieve valuable practical outcomes in regenerative medicine and drug development. Organoids show properties of functional organs and represent an alternative to cell models in conventional two-dimensional differentiation platforms; moreover, organoids can be used to investigate mechanisms of development and disease, drug discovery and toxicity assessment. Towards a more complex and advanced organoid model, it is essential to incorporate multiple cell lineages including developing vessels. Using a self-condensation method, we recently demonstrated self-organizing "organ buds" of diverse systems together with human mesenchymal and endothelial progenitors, proposing a new reverse engineering method to generate a more complex organoid structure. In this section, we review characters of organ bud technology based on two important principles: self-condensation and self-organization focusing on liver bud as an example, and discuss their practicality in regenerative medicine and potential as research tools for developmental biology and drug discovery.

  8. Revitalizing the Space Shuttle's Thermal Protection System with Reverse Engineering and 3D Vision Technology

    NASA Technical Reports Server (NTRS)

    Wilson, Brad; Galatzer, Yishai

    2008-01-01

    The Space Shuttle is protected by a Thermal Protection System (TPS) made of tens of thousands of individually shaped heat protection tile. With every flight, tiles are damaged on take-off and return to earth. After each mission, the heat tiles must be fixed or replaced depending on the level of damage. As part of the return to flight mission, the TPS requirements are more stringent, leading to a significant increase in heat tile replacements. The replacement operation requires scanning tile cavities, and in some cases the actual tiles. The 3D scan data is used to reverse engineer each tile into a precise CAD model, which in turn, is exported to a CAM system for the manufacture of the heat protection tile. Scanning is performed while other activities are going on in the shuttle processing facility. Many technicians work simultaneously on the space shuttle structure, which results in structural movements and vibrations. This paper will cover a portable, ultra-fast data acquisition approach used to scan surfaces in this unstable environment.

  9. Engineered reversal of drug resistance in cancer cells--metastases suppressor factors as change agents.

    PubMed

    Yadav, Vinod Kumar; Kumar, Akinchan; Mann, Anita; Aggarwal, Suruchi; Kumar, Maneesh; Roy, Sumitabho Deb; Pore, Subrata Kumar; Banerjee, Rajkumar; Mahesh Kumar, Jerald; Thakur, Ram Krishna; Chowdhury, Shantanu

    2014-01-01

    Building molecular correlates of drug resistance in cancer and exploiting them for therapeutic intervention remains a pressing clinical need. To identify factors that impact drug resistance herein we built a model that couples inherent cell-based response toward drugs with transcriptomes of resistant/sensitive cells. To test this model, we focused on a group of genes called metastasis suppressor genes (MSGs) that influence aggressiveness and metastatic potential of cancers. Interestingly, modeling of 84 000 drug response transcriptome combinations predicted multiple MSGs to be associated with resistance of different cell types and drugs. As a case study, on inducing MSG levels in a drug resistant breast cancer line resistance to anticancer drugs caerulomycin, camptothecin and topotecan decreased by more than 50-60%, in both culture conditions and also in tumors generated in mice, in contrast to control un-induced cells. To our knowledge, this is the first demonstration of engineered reversal of drug resistance in cancer cells based on a model that exploits inherent cellular response profiles.

  10. Antibody engineering: facing new challenges in cancer therapy.

    PubMed

    Sanz, Laura; Cuesta, Angel M; Compte, Marta; Alvarez-Vallina, Luis

    2005-06-01

    Antibody-based therapeutics are beginning to realize the promise enclosed in their early denomination as magic bullets. Initial disappointment has turned into clinical and commercial success, and engineered antibodies currently represent over 30% of biopharmaceuticals in clinical trials. Recent structural and functional data have allowed the design of a new generation of therapeutic antibodies, with strategies ranging from complement-mediated and antibody-dependant cellular cytotoxicity enhancement to improved cytotoxic payloads using toxins, drugs, radionucleids and viral delivery. This review considers the structure of different types of recombinant antibodies, their mechanism of action and how their efficacy has been increased using a broad array of approaches. We will also focus on the additional benefits offered by the use of gene therapy methods for the in vivo production of therapeutic antibodies.

  11. Smartphone measurement engineering - Innovative challenges for science & education, instrumentation & training

    NASA Astrophysics Data System (ADS)

    Hofmann, D.; Dittrich, P.-G.; Duentsch, E.

    2010-07-01

    Smartphones have an enormous conceptual and structural influence on measurement science & education, instrumentation & training. Smartphones are matured. They became convenient, reliable and affordable. In 2009 worldwide 174 million Smartphones has been delivered. Measurement with Smartphones is ready for the future. In only 10 years the German vision industry tripled its global sales volume to one Billion Euro/Year. Machine vision is used for mobile object identification, contactless industrial quality control, personalized health care, remote facility and transport management, safety critical surveillance and all tasks which are too complex for the human eye or too monotonous for the human brain. Aim of the paper is to describe selected success stories for the application of Smartphones for measurement engineering in science and education, instrumentation and training.

  12. Current Trends and Challenges in Biointerfaces Science and Engineering.

    PubMed

    Ross, A M; Lahann, J

    2015-01-01

    The cellular microenvironment is extremely complex, and a plethora of materials and methods have been employed to mimic its properties in vitro. In particular, scientists and engineers have taken an interdisciplinary approach in their creation of synthetic biointerfaces that replicate chemical and physical aspects of the cellular microenvironment. Here the focus is on the use of synthetic materials or a combination of synthetic and biological ligands to recapitulate the defined surface chemistries, microstructure, and function of the cellular microenvironment for a myriad of biomedical applications. Specifically, strategies for altering the surface of these environments using self-assembled monolayers, polymer coatings, and their combination with patterned biological ligands are explored. Furthermore, methods for augmenting an important physical property of the cellular microenvironment, topography, are highlighted, and the advantages and disadvantages of these approaches are discussed. Finally, the progress of materials for prolonged stem cell culture, a key component in the translation of stem cell therapeutics for clinical use, is featured.

  13. Changes and challenges in the Software Engineering Laboratory

    NASA Technical Reports Server (NTRS)

    Pajerski, Rose

    1994-01-01

    Since 1976, the Software Engineering Laboratory (SEL) has been dedicated to understanding and improving the way in which one NASA organization, the Flight Dynamics Division (FDD), develops, maintains, and manages complex flight dynamics systems. The SEL is composed of three member organizations: NASA/GSFC, the University of Maryland, and Computer Sciences Corporation. During the past 18 years, the SEL's overall goal has remained the same: to improve the FDD's software products and processes in a measured manner. This requires that each development and maintenance effort be viewed, in part, as a SEL experiment which examines a specific technology or builds a model of interest for use on subsequent efforts. The SEL has undertaken many technology studies while developing operational support systems for numerous NASA spacecraft missions.

  14. Challenges and promises of integrating knowledge engineering and qualitative methods

    NASA Astrophysics Data System (ADS)

    Lundberg, C. Gustav; Holm, Gunilla

    Our goal is to expose some of the close ties that exist between knowledge engineering (KE) and qualitative methodology (QM). Many key concepts of qualitative research, for example meaning, commonsense, understanding, and everyday life, overlap with central research concerns in artificial intelligence. These shared interests constitute a largely unexplored avenue for interdisciplinary cooperation. We compare and take some steps toward integrating two historically diverse methodologies by exploring the commonalities of KE and QM both from a substantive and a methodological/technical perspective. In the second part of this essay, we address knowledge acquisition problems and procedures. Knowledge acquisition within KE has been based primarily on cognitive psychology/science foundations, whereas knowledge acquisition within QM has a broader foundation in phenomenology, symbolic interactionism, and ethnomethodology. Our discussion and examples are interdisciplinary in nature. We do not suggest that there is a clash between the KE and QM frameworks, but rather that the lack of communication potentially may limit each framework's future development.

  15. Challenges of the biomedical engineering education in Europe.

    PubMed

    Magjarevic, Ratko; Lackovic, Igor; Bliznakov, Zhivko; Pallikarakis, Nicolas

    2010-01-01

    Higher education in Europe has passed through a very dynamic period of changes during the last ten years. Since the signing of the Bologna Declaration in 1999 by the Ministers of Education from the EU states, European higher education system has aimed toward establishing harmonized programs enabling students and teachers to extensively exchange knowledge, ideas and skills. Education in the field of Biomedical Engineering has experienced changes also because of the research and development in the field which was more intensive than in other fields. Besides research in new power sources, it is the most intensive and productive research field. Much of the development in BME education in Europe is influenced by the European research policy expressed through the 7th Framework Programme where health is the major theme. In order to foster and support the changes in the European Higher Education Area (EHEA) according to the needs of research sector and the labor market, the Tempus scheme of projects was established. Tempus scheme aims to support the modernization of higher education and create an area of co-operation in the countries surrounding the EU. Our Tempus project, CRH-BME "Curricula Reformation and Harmonization in the field of Biomedical Engineering" aims to create guidelines for updating existing curricula in the field of BME in Europe in order to meet recent and future developments in the area, address new emerging interdisciplinary domains that appear as the result of the R&D progress and respond to the BME job market demands. In this paper, some policy and economic factors affecting BME education in Europe are discussed and the results of a BME education survey we prepared within the Tempus CHR-BME project are presented. The number of BME programmes in Europe has in the last decade significantly increased and there are more BME specializations as the result of growing complexity of the research and production in the field.

  16. Effect of Target-type Thrust Reverser on Transonic Aerodynamic Characteristics of a Single-engine Fighter Model

    NASA Technical Reports Server (NTRS)

    Swihert, John M

    1958-01-01

    A brief investigation of a target-type thrust reverser on a single-engine fighter model has been conducted in the Langley 16-foot transonic tunnel at Mach numbers from 0.20 to 1.05.At Mach numbers of 0.80, 0.92, and 1.05, a hydrogen peroxide turbojet-engine simulator was operated with the thrust reverser extended. The angle of attack was varied from 0 degrees to 5 degrees at these Mach numbers. The Reynolds number of the free stream, based on the mean aerodynamic chord, was about 5 x 10(6). It was estimated that reversed jet operations separated the model boundary-layer flow over the upper surface of the horizontal tail and upper part of the afterbody. This resulted in a positive pitch increment due to reversed jet operation. Jet-on operation also tended to stabilize the severe lateral oscillations which occurred with the reverser extended and the jet off. It appeared that these jet-off oscillations were the result of an alternating separation and reattachment of the flow on the rearmost portions of the fuselage afterbody.

  17. Challenges in Requirements Engineering: A Research Agenda for Conceptual Modeling

    NASA Astrophysics Data System (ADS)

    March, Salvatore T.; Allen, Gove N.

    Domains for which information systems are developed deal primarily with social constructions—conceptual objects and attributes created by human intentions and for human purposes. Information systems play an active role in these domains. They document the creation of new conceptual objects, record and ascribe values to their attributes, initiate actions within the domain, track activities performed, and infer conclusions based on the application of rules that govern how the domain is affected when socially-defined and identified causal events occur. Emerging applications of information technologies evaluate such business rules, learn from experience, and adapt to changes in the domain. Conceptual modeling grammars aimed at representing their system requirements must include conceptual objects, socially-defined events, and the rules pertaining to them. We identify challenges to conceptual modeling research and pose an ontology of the artificial as a step toward meeting them.

  18. Space Station assembly sequence planning - An engineering and operational challenge

    NASA Technical Reports Server (NTRS)

    Kaidy, James T.; Bastedo, William G.

    1988-01-01

    This paper discusses the Space Station assembly sequence planning and development process. It presents the planning methodologies from both historial and current perspectives. It is shown that planning the assembly sequence is a new and unique challenge and its solution requires the simultaneous satisfaction of many diverse variables and constants. The considerations which influence the development of the assembly sequence include launch vehicle integration and lift capabilities, on-orbit assembly flight operations, vehicle flight dynamics, spacecraft system capabilities and resource availability. Many of these considerations are described in this paper. In addition, the examples presented demonstrate the current process for assembly sequence planning and show many of the complex trade-offs that must be performed.

  19. Periodontal regeneration: a challenge for the tissue engineer?

    PubMed

    Hughes, F J; Ghuman, M; Talal, A

    2010-12-01

    Periodontitis affects around 15 per cent of human adult populations. While periodontal treatment aimed at removing the bacterial cause of the disease is generally very successful, the ability predictably to regenerate the damaged tissues remains a major unmet objective for new treatment strategies. Existing treatments include the use of space-maintaining barrier membranes (guided tissue regeneration), use of graft materials, and application of bioactive molecules to induce regeneration, but their overall effects are relatively modest and restricted in application. The periodontal ligament is rich in mesenchymal stem cells, and the understanding of the signalling molecules that may regulate their differentation has increased enormously in recent years. Applying these principles for the development of new tissue engineering strategies for periodontal regeneration will require further work to determine the efficacy of current experimental preclinical treatments, including pharmacological application of growth factors such as bone morphogenetic proteins (BMPs) or Wnts, use of autologous stem cell reimplantation strategies, and development of improved biomaterial scaffolds. This article describes the background to this problem, addresses the current status of periodontal regeneration, including the background biology, and discusses the potential for some of these experimental therapies to achieve the goal of clinically predictable periodontal regeneration.

  20. Representation and misrepresentation: Tufte and the Morton Thiokol engineers on the Challenger.

    PubMed

    Robison, Wade; Boisjoly, Roger; Hoeker, David; Young, Stefan

    2002-01-01

    This paper examines the role of the Morton Thiokol engineers in the decisions surrounding the launch of the Challenger, particularly with reference to an analysis of this event by Edward Tufte. The engineers at Morton Thiokol recommended against the launch of Challenger because the projected launch temperature between 26 degrees F to 29 degrees F was far outside their field database of successful launches. The engineers had asked for, but not received, data necessary to determine the cause of massive blow-by on the launch the previous January, and they had informed their managers and NASA that continuing flights could be catastrophic if the cause of the problems with the launches was not discovered. The authors conclude that the engineers thus did what they were ethically as well as professionally obligated to do.

  1. New Mass Properties Engineers Aerospace Ballasting Challenge Facilitated by the SAWE Community

    NASA Technical Reports Server (NTRS)

    Cutright, Amanda; Shaughnessy, Brendan

    2010-01-01

    The discipline of Mass Properties Engineering tends to find the engineers; not typically vice versa. In this case, two engineers quickly found their new responsibilities deep in many aspects of mass properties engineering and required to meet technical challenges in a fast paced environment. As part of NASA's Constellation Program, a series of flight tests will be conducted to evaluate components of the new spacecraft launch vehicles. One of these tests is the Pad Abort 1 (PA-1) flight test which will test the Launch Abort System (LAS), a system designed to provide escape for astronauts in the event of an emergency. The Flight Test Articles (FTA) used in this flight test are required to match mass properties corresponding to the operational vehicle, which has a continually evolving design. Additionally, since the structure and subsystems for the Orion Crew Module (CM) FTA are simplified versions of the final product, thousands of pounds of ballast are necessary to achieve the desired mass properties. These new mass properties engineers are responsible for many mass properties aspects in support of the flight test, including meeting the ballasting challenge for the CM Boilerplate FTA. SAWE expert and experienced mass properties engineers, both those that are directly on the team and many that supported via a variety of Society venues, significantly contributed to facilitating the success of addressing this particular mass properties ballasting challenge, in addition to many other challenges along the way. This paper discusses the details regarding the technical aspects of this particular mass properties challenge, as well as identifies recommendations for new mass properties engineers that were learned from the SAWE community along the way.

  2. The management challenge for household waste in emerging economies like Brazil: realistic source separation and activation of reverse logistics.

    PubMed

    Fehr, M

    2014-09-01

    Business opportunities in the household waste sector in emerging economies still evolve around the activities of bulk collection and tipping with an open material balance. This research, conducted in Brazil, pursued the objective of shifting opportunities from tipping to reverse logistics in order to close the balance. To do this, it illustrated how specific knowledge of sorted waste composition and reverse logistics operations can be used to determine realistic temporal and quantitative landfill diversion targets in an emerging economy context. Experimentation constructed and confirmed the recycling trilogy that consists of source separation, collection infrastructure and reverse logistics. The study on source separation demonstrated the vital difference between raw and sorted waste compositions. Raw waste contained 70% biodegradable and 30% inert matter. Source separation produced 47% biodegradable, 20% inert and 33% mixed material. The study on collection infrastructure developed the necessary receiving facilities. The study on reverse logistics identified private operators capable of collecting and processing all separated inert items. Recycling activities for biodegradable material were scarce and erratic. Only farmers would take the material as animal feed. No composting initiatives existed. The management challenge was identified as stimulating these activities in order to complete the trilogy and divert the 47% source-separated biodegradable discards from the landfills. © The Author(s) 2014.

  3. Ab initio calculations for industrial materials engineering: successes and challenges.

    PubMed

    Wimmer, Erich; Najafabadi, Reza; Young, George A; Ballard, Jake D; Angeliu, Thomas M; Vollmer, James; Chambers, James J; Niimi, Hiroaki; Shaw, Judy B; Freeman, Clive; Christensen, Mikael; Wolf, Walter; Saxe, Paul

    2010-09-29

    Computational materials science based on ab initio calculations has become an important partner to experiment. This is demonstrated here for the effect of impurities and alloying elements on the strength of a Zr twist grain boundary, the dissociative adsorption and diffusion of iodine on a zirconium surface, the diffusion of oxygen atoms in a Ni twist grain boundary and in bulk Ni, and the dependence of the work function of a TiN-HfO(2) junction on the replacement of N by O atoms. In all of these cases, computations provide atomic-scale understanding as well as quantitative materials property data of value to industrial research and development. There are two key challenges in applying ab initio calculations, namely a higher accuracy in the electronic energy and the efficient exploration of large parts of the configurational space. While progress in these areas is fueled by advances in computer hardware, innovative theoretical concepts combined with systematic large-scale computations will be needed to realize the full potential of ab initio calculations for industrial applications.

  4. Engineering challenges of the acoustics of a political convention

    NASA Astrophysics Data System (ADS)

    Randorff, Jack E.

    2002-05-01

    The acoustical challenges encountered during the 2000 Republican Convention are discussed. The convention has held in Philadelphia, Pennsylvania's First Union Center. This venue is a dual-purpose facility catering to professional basketball and professional ice hockey. The acoustical needs of the delegates and the broadcast audience are discussed. The technical performance requirements of convention sound reinforcement and media network broadcast feed are outlined. The necessary technical and performance trade-offs are enumerated with respect to the physical constraints, schedule requirements, budget limitations, and technical planning committee expectations. The conversion of a major sporting arena to a large-scale meeting room with reverberation times and general room conditions conducive to good listening was a significant undertaking. The site had been chosen for a preliminary screening visit approximately 2 years before. This presentation is a followup to ``Acoustics of Political Conventions-A Review,'' delivered at the Acoustical Society of America 139th Meeting in Atlanta in June 2000, 2 months before the convention in Philadelphia.

  5. The hermeneutic challenge of genetic engineering: Habermas and the transhumanists.

    PubMed

    Edgar, Andrew

    2009-06-01

    The purpose of this paper is to explore the impact that developments in transhumanist technologies may have upon human cultures (and thus upon the lifeworld), and to do so by exploring a potential debate between Habermas and the transhumanists. Transhumanists, such as Nick Bostrom, typically see the potential in genetic and other technologies for positively expanding and transcending human nature. In contrast, Habermas is a representative of those who are fearful of this technology, suggesting that it will compound the deleterious effects of the colonisation of the lifeworld, further constraining human autonomy and undermining the meaningfulness of the lifeworld by expanding the technological control and manipulation of humanity. It will be argued that these opposed positions are grounded in fundamentally different understandings of the consequences of scientific and technological advance. On one level, the transhumanists remain confident that the lifeworld has within it the resources necessary to find meaning and purpose in a society deeply infused by genetic technology. Habermas disagrees. On another level, the difference is articulated by Horkheimer and Adorno in Dialectic of Enlightenment, primarily by challenging what may be understood as a Baconian faith in science as a project for the domination of nature (where nature is an infinitely malleable material, to be dominated and shaped, without adverse consequences, purely for the purposes of human survival). While the transhumanists broadly embrace this faith, Habermas returns to something akin to Horkheimer and Adorno's pessimistic scepticism.

  6. Umbilical cord blood graft engineering: challenges and opportunities.

    PubMed

    Thompson, P A; Rezvani, K; Hosing, C M; Oran, B; Olson, A L; Popat, U R; Alousi, A M; Shah, N D; Parmar, S; Bollard, C; Hanley, P; Kebriaei, P; Cooper, L; Kellner, J; McNiece, I K; Shpall, E J

    2015-06-01

    We are entering a very exciting era in umbilical cord blood transplantation (UCBT), where many of the associated formidable challenges may become treatable by ex vivo graft manipulation and/or adoptive immunotherapy utilizing specific cellular products. We envisage the use of double UCBT rather than single UCBT for most patients; this allows for greater ability to treat larger patients as well as to manipulate the graft. Ex vivo expansion and/or fucosylation of one cord will achieve more rapid engraftment, minimize the period of neutropenia and also give certainty that the other cord will provide long-term engraftment/immune reconstitution. The non-expanded (and future dominant) cord could be chosen for characteristics such as better HLA matching to minimize GvHD, or larger cell counts to enable part of the unit to be utilized for the development of specific cellular therapies such as the production of virus-specific T-cells or chimeric-antigen receptor T-cells which are reviewed in this study.

  7. Reverse Engineering and Security Evaluation of Commercial Tags for RFID-Based IoT Applications.

    PubMed

    Fernández-Caramés, Tiago M; Fraga-Lamas, Paula; Suárez-Albela, Manuel; Castedo, Luis

    2016-12-24

    The Internet of Things (IoT) is a distributed system of physical objects that requires the seamless integration of hardware (e.g., sensors, actuators, electronics) and network communications in order to collect and exchange data. IoT smart objects need to be somehow identified to determine the origin of the data and to automatically detect the elements around us. One of the best positioned technologies to perform identification is RFID (Radio Frequency Identification), which in the last years has gained a lot of popularity in applications like access control, payment cards or logistics. Despite its popularity, RFID security has not been properly handled in numerous applications. To foster security in such applications, this article includes three main contributions. First, in order to establish the basics, a detailed review of the most common flaws found in RFID-based IoT systems is provided, including the latest attacks described in the literature. Second, a novel methodology that eases the detection and mitigation of such flaws is presented. Third, the latest RFID security tools are analyzed and the methodology proposed is applied through one of them (Proxmark 3) to validate it. Thus, the methodology is tested in different scenarios where tags are commonly used for identification. In such systems it was possible to clone transponders, extract information, and even emulate both tags and readers. Therefore, it is shown that the methodology proposed is useful for auditing security and reverse engineering RFID communications in IoT applications. It must be noted that, although this paper is aimed at fostering RFID communications security in IoT applications, the methodology can be applied to any RFID communications protocol.

  8. Reverse Engineering and Security Evaluation of Commercial Tags for RFID-Based IoT Applications

    PubMed Central

    Fernández-Caramés, Tiago M.; Fraga-Lamas, Paula; Suárez-Albela, Manuel; Castedo, Luis

    2016-01-01

    The Internet of Things (IoT) is a distributed system of physical objects that requires the seamless integration of hardware (e.g., sensors, actuators, electronics) and network communications in order to collect and exchange data. IoT smart objects need to be somehow identified to determine the origin of the data and to automatically detect the elements around us. One of the best positioned technologies to perform identification is RFID (Radio Frequency Identification), which in the last years has gained a lot of popularity in applications like access control, payment cards or logistics. Despite its popularity, RFID security has not been properly handled in numerous applications. To foster security in such applications, this article includes three main contributions. First, in order to establish the basics, a detailed review of the most common flaws found in RFID-based IoT systems is provided, including the latest attacks described in the literature. Second, a novel methodology that eases the detection and mitigation of such flaws is presented. Third, the latest RFID security tools are analyzed and the methodology proposed is applied through one of them (Proxmark 3) to validate it. Thus, the methodology is tested in different scenarios where tags are commonly used for identification. In such systems it was possible to clone transponders, extract information, and even emulate both tags and readers. Therefore, it is shown that the methodology proposed is useful for auditing security and reverse engineering RFID communications in IoT applications. It must be noted that, although this paper is aimed at fostering RFID communications security in IoT applications, the methodology can be applied to any RFID communications protocol. PMID:28029119

  9. Reverse Engineering and Evaluation of Prediction Models for Progression to Type 2 Diabetes

    PubMed Central

    Anderson, Jeffrey P.; Parikh, Jignesh R.; Shenfeld, Daniel K.; Ivanov, Vladimir; Marks, Casey; Church, Bruce W.; Laramie, Jason M.; Mardekian, Jack; Piper, Beth Anne; Willke, Richard J.; Rublee, Dale A.

    2015-01-01

    Background: Application of novel machine learning approaches to electronic health record (EHR) data could provide valuable insights into disease processes. We utilized this approach to build predictive models for progression to prediabetes and type 2 diabetes (T2D). Methods: Using a novel analytical platform (Reverse Engineering and Forward Simulation [REFS]), we built prediction model ensembles for progression to prediabetes or T2D from an aggregated EHR data sample. REFS relies on a Bayesian scoring algorithm to explore a wide model space, and outputs a distribution of risk estimates from an ensemble of prediction models. We retrospectively followed 24 331 adults for transitions to prediabetes or T2D, 2007-2012. Accuracy of prediction models was assessed using an area under the curve (AUC) statistic, and validated in an independent data set. Results: Our primary ensemble of models accurately predicted progression to T2D (AUC = 0.76), and was validated out of sample (AUC = 0.78). Models of progression to T2D consisted primarily of established risk factors (blood glucose, blood pressure, triglycerides, hypertension, lipid disorders, socioeconomic factors), whereas models of progression to prediabetes included novel factors (high-density lipoprotein, alanine aminotransferase, C-reactive protein, body temperature; AUC = 0.70). Conclusions: We constructed accurate prediction models from EHR data using a hypothesis-free machine learning approach. Identification of established risk factors for T2D serves as proof of concept for this analytical approach, while novel factors selected by REFS represent emerging areas of T2D research. This methodology has potentially valuable downstream applications to personalized medicine and clinical research. PMID:26685993

  10. Effect of engineered environment on microbial community structure in biofilter and biofilm on reverse osmosis membrane.

    PubMed

    Jeong, Sanghyun; Cho, Kyungjin; Jeong, Dawoon; Lee, Seockheon; Leiknes, TorOve; Vigneswaran, Saravanamuthu; Bae, Hyokwan

    2017-11-01

    Four dual media filters (DMFs) were operated in a biofiltration mode with different engineered environments (DMF I and II: coagulation with/without acidification and DMF III and IV: without/with chlorination). Designed biofilm enrichment reactors (BERs) containing the removable reverse osmosis (RO) coupons, were connected at the end of the DMFs in parallel to analyze the biofilm on the RO membrane by DMF effluents. Filtration performances were evaluated in terms of dissolved organic carbon (DOC) and assimilable organic carbon (AOC). Organic foulants on the RO membrane were also quantified and fractionized. The bacterial community structures in liquid (seawater and effluent) and biofilm (DMF and RO) samples were analyzed using 454-pyrosequencing. The DMF IV fed with the chlorinated seawater demonstrated the highest reductions of DOC including LMW-N as well as AOC among the other DMFs. The DMF IV was also effective in reducing organic foulants on the RO membrane surface. The bacterial community structure was grouped according to the sample phase (i.e., liquid and biofilm samples), sampling location (i.e., DMF and RO samples), and chlorination (chlorinated and non-chlorinated samples). In particular, the biofilm community in the DMF IV differed from the other DMF treatments, suggesting that chlorination exerted as stronger selective pressure than pH adjustment or coagulation on the biofilm community. In the DMF IV, several chemoorganotrophic chlorine-resistant biofilm-forming bacteria such as Hyphomonas, Erythrobacter, and Sphingomonas were predominant, and they may enhance organic carbon degradation efficiency. Diverse halophilic or halotolerant organic degraders were also found in other DMFs (i.e., DMF I, II, and III). Various kinds of dominant biofilm-forming bacteria were also investigated in RO membrane samples; the results provided possible candidates that cause biofouling when DMF process is applied as the pretreatment option for the RO process. Copyright

  11. Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE) of the November 2004 Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Datta-Barua, S.; Bust, G.; Crowley, G.; Curtis, N.; Reynolds, A.

    2008-12-01

    One of the current limitations to the community's understanding of ionospheric processes is knowledge of the local physical drivers responsible for the distribution of ionospheric electron density. Direct measurement of these drivers is infrequent and spatially scarce. Our ongoing goal has been to use measurements that are plentiful, such as TEC-based density specification, to infer the drivers. This technique we call Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE). The EMPIRE algorithm and validation methods, using simulated ionospheric data from the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM-ASPEN) physics-based model [Crowley et al., 1999], were described by Bust et al. [2008]. The EMPIRE weighted least squares estimates of the field-aligned neutral winds in the equatorial region were in reasonable agreement with the TIMEGCM background model "true" winds. The other drivers, such as production, loss, diffusion, gravity, and drifts, were modeled as known quantities. Here we present results, based upon an improved algorithm, that estimate corrections to other physical drivers, such as diffusion, ExB drifts, production and loss, simultaneously with estimating the neutral winds. In addition, we apply the new algorithm to actual estimates of the 4D electron density field, obtained from the ionospheric data assimilation algorithm IDA4D, for a quiet day and for the November 2004 magnetic storm. The EMPIRE estimates of the field-aligned velocity terms in the continuity equation are compared to Arecibo incoherent scatter radar measurements, when available, for validation. Bust, G. S., S. Datta-Barua, G. Crowley, and N. Curtis [2008], "Estimation of neutral winds from 4D ionospheric imaging," presented at the XXIX General Assembly of the International Union of Radio Science (URSI), Chicago, IL, 7-16 Aug 2008. Crowley, G., C. Freitas, A. Ridley, D. Winningham, R. G. Roble, and A. D. Richmond, "Next

  12. Design and manufacture of customized dental implants by using reverse engineering and selective laser melting technology.

    PubMed

    Chen, Jianyu; Zhang, Zhiguang; Chen, Xianshuai; Zhang, Chunyu; Zhang, Gong; Xu, Zhewu

    2014-11-01

    Recently a new therapeutic concept of patient-specific implant dentistry has been advanced based on computer-aided design/computer-aided manufacturing technology. However, a comprehensive study of the design and 3-dimensional (3D) printing of the customized implants, their mechanical properties, and their biomechanical behavior is lacking. The purpose of this study was to evaluate the mechanical and biomechanical performance of a novel custom-made dental implant fabricated by the selective laser melting technique with simulation and in vitro experimental studies. Two types of customized implants were designed by using reverse engineering: a root-analog implant and a root-analog threaded implant. The titanium implants were printed layer by layer with the selective laser melting technique. The relative density, surface roughness, tensile properties, bend strength, and dimensional accuracy of the specimens were evaluated. Nonlinear and linear finite element analysis and experimental studies were used to investigate the stress distribution, micromotion, and primary stability of the implants. Selective laser melting 3D printing technology was able to reproduce the customized implant designs and produce high density and strength and adequate dimensional accuracy. Better stress distribution and lower maximum micromotions were observed for the root-analog threaded implant model than for the root-analog implant model. In the experimental tests, the implant stability quotient and pull-out strength of the 2 types of implants indicated that better primary stability can be obtained with a root-analog threaded implant design. Selective laser melting proved to be an efficient means of printing fully dense customized implants with high strength and sufficient dimensional accuracy. Adding the threaded characteristic to the customized root-analog threaded implant design maintained the approximate geometry of the natural root and exhibited better stress distribution and

  13. [Correction of progressive hemifacial atrophy using dermis-fat graft and Medpor implant shaped by reverse engineering technique].

    PubMed

    Zhang, Jun-rui; Wei, Jian-hua; Li, Yun-peng; Feng, Xing-hua

    2009-01-01

    To evaluate the therapeutic effect of dermis-fat graft combined with Medpor implant shaped by reverse engineering technique in the correction of the progressive hemifacial atrophy. A skull model was made by rapid prototyping and the bony deficiency model was acquired with reverse engineering technique. The Medpor implant was shaped precisely based on the deficiency model and implanted with dermis-fat graft at the same stage. 11 cases were treated successfully without infection, necrosis and rejection. The patients were followed up for six months to one year with satisfactory cosmetic improvement. The dermis-fat graft survived without obvious absorption. The technique can correct both the bony and soft tissue deficiency for progressive hemifacial atrophy. It is very practical and easily performed with reliant results and less morbidity.

  14. Challenges and Opportunities: Building a Relationship Between a Department of Biomedical Engineering and a Medical School.

    PubMed

    George, Steven C; Meyerand, M Elizabeth

    2017-03-01

    A department of biomedical engineering can significantly enhance the impact of their research and training programs if a productive relationship with a medical school can be established. In order to develop such a relationship, significant hurdles must be overcome. This editorial summarizes some of the major challenges and opportunities for a department of biomedical engineering as they seek to build or enhance a relationship with a medical school. The ideas were formulated by engaging the collective wisdom from the Council of Chairs of the biomedical engineering departments.

  15. Engineering Ethics Education : Its Necessity, Objectives, Methods, Current State, and Challenges

    NASA Astrophysics Data System (ADS)

    Fudano, Jun

    The importance of engineering ethics education has become widely recognized in the industrialized countries including Japan. This paper examines the background against which engineering ethics education is required, and reviews its objectives, methods, and challenges, as well as its current state. In pointing out important issues associated with the apparent acceptance and quantitative development of ethics education, especially after the establishment of the Japan Accreditation Board for Engineering Education in 1999, the author stresses that the most serious problem is the lack of common understanding on the objectives of engineering ethics education. As a strategy to improve the situation, the so-called “Ethics-across-the-Curriculum” approach is introduced. The author also claims that business/organization ethics which is consistent with engineering ethics should be promoted in Japan.

  16. Reversal of type 1 diabetes by engineering a glucose sensor in skeletal muscle.

    PubMed

    Mas, Alex; Montané, Joel; Anguela, Xavier M; Muñoz, Sergio; Douar, Anne M; Riu, Efren; Otaegui, Pedro; Bosch, Fatima

    2006-06-01

    Type 1 diabetic patients develop severe secondary complications because insulin treatment does not guarantee normoglycemia. Thus, efficient regulation of glucose homeostasis is a major challenge in diabetes therapy. Skeletal muscle is the most important tissue for glucose disposal after a meal. However, the lack of insulin during diabetes impairs glucose uptake. To increase glucose removal from blood, skeletal muscle of transgenic mice was engineered both to produce basal levels of insulin and to express the liver enzyme glucokinase. After streptozotozin (STZ) administration of double-transgenic mice, a synergic action in skeletal muscle between the insulin produced and the increased glucose phosphorylation by glucokinase was established, preventing hyperglycemia and metabolic alterations. These findings suggested that insulin and glucokinase might be expressed in skeletal muscle, using adeno-associated viral 1 (AAV1) vectors as a new gene therapy approach for diabetes. AAV1-Ins+GK-treated diabetic mice restored and maintained normoglycemia in fed and fasted conditions for >4 months after STZ administration. Furthermore, these mice showed normalization of metabolic parameters, glucose tolerance, and food and fluid intake. Therefore, the joint action of basal insulin production and glucokinase activity may generate a "glucose sensor" in skeletal muscle that allows proper regulation of glycemia in diabetic animals and thus prevents secondary complications.

  17. A parallel implementation of the network identification by multiple regression (NIR) algorithm to reverse-engineer regulatory gene networks.

    PubMed

    Gregoretti, Francesco; Belcastro, Vincenzo; di Bernardo, Diego; Oliva, Gennaro

    2010-04-21

    The reverse engineering of gene regulatory networks using gene expression profile data has become crucial to gain novel biological knowledge. Large amounts of data that need to be analyzed are currently being produced due to advances in microarray technologies. Using current reverse engineering algorithms to analyze large data sets can be very computational-intensive. These emerging computational requirements can be met using parallel computing techniques. It has been shown that the Network Identification by multiple Regression (NIR) algorithm performs better than the other ready-to-use reverse engineering software. However it cannot be used with large networks with thousands of nodes--as is the case in biological networks--due to the high time and space complexity. In this work we overcome this limitation by designing and developing a parallel version of the NIR algorithm. The new implementation of the algorithm reaches a very good accuracy even for large gene networks, improving our understanding of the gene regulatory networks that is crucial for a wide range of biomedical applications.

  18. A comprehensive assessment of methods for de-novo reverse-engineering of genome-scale regulatory networks.

    PubMed

    Narendra, Varun; Lytkin, Nikita I; Aliferis, Constantin F; Statnikov, Alexander

    2011-01-01

    De-novo reverse-engineering of genome-scale regulatory networks is an increasingly important objective for biological and translational research. While many methods have been recently developed for this task, their absolute and relative performance remains poorly understood. The present study conducts a rigorous performance assessment of 32 computational methods/variants for de-novo reverse-engineering of genome-scale regulatory networks by benchmarking these methods in 15 high-quality datasets and gold-standards of experimentally verified mechanistic knowledge. The results of this study show that some methods need to be substantially improved upon, while others should be used routinely. Our results also demonstrate that several univariate methods provide a "gatekeeper" performance threshold that should be applied when method developers assess the performance of their novel multivariate algorithms. Finally, the results of this study can be used to show practical utility and to establish guidelines for everyday use of reverse-engineering algorithms, aiming towards creation of automated data-analysis protocols and software systems.

  19. Educational Challenges for Engineering. Keynote Address, Engineering in the Service of Society: New Educational Programs. IEEE Workshop Record (University of Kentucky, Lexington, August 26-27, 1974).

    ERIC Educational Resources Information Center

    Truxal, John G.

    Cited are the educational challenges of undergraduate, graduate, and professional engineering programs; the main emphasis is on the challente to provide engineering education for non-engineering students at both the undergraduate and adult levels. The need for such a program stems from a conviction that no citizen can be considered educated in…

  20. The South African Engineering Education Model with a European Perspective: History, Analogies, Transformations and Challenges

    ERIC Educational Resources Information Center

    Kloot, Bruce; Rouvrais, Siegfried

    2017-01-01

    South Africa, with its national cultural diversity and post-apartheid challenges and commitments, finds echoes in the European context, especially considering the imperatives of openness and non-discrimination in higher education. With an historical tradition of excellence in engineering education, the emphasis on supporting educationally…

  1. The European Project Semester at ISEP: The Challenge of Educating Global Engineers

    ERIC Educational Resources Information Center

    Malheiro, Benedita; Silva, Manuel; Ribeiro, Maria Cristina; Guedes, Pedro; Ferreira, Paulo

    2015-01-01

    Current engineering education challenges require approaches that promote scientific, technical, design and complementary skills while fostering autonomy, innovation and responsibility. The European Project Semester (EPS) at Instituto Superior de Engenharia do Porto (ISEP) (EPS@ISEP) is a one semester project-based learning programme (30 European…

  2. The European Project Semester at ISEP: The Challenge of Educating Global Engineers

    ERIC Educational Resources Information Center

    Malheiro, Benedita; Silva, Manuel; Ribeiro, Maria Cristina; Guedes, Pedro; Ferreira, Paulo

    2015-01-01

    Current engineering education challenges require approaches that promote scientific, technical, design and complementary skills while fostering autonomy, innovation and responsibility. The European Project Semester (EPS) at Instituto Superior de Engenharia do Porto (ISEP) (EPS@ISEP) is a one semester project-based learning programme (30 European…

  3. Engineering Ethics and Self-Organizing Models of Human Development: Opportunities and Challenges.

    PubMed

    Hyun, Insoo

    2017-09-12

    Incorporating engineering ethics early during the planning stages of organoid and gastruloid research may help prevent future confusion about the moral status of complex models of human development. However, the intrinsic self-organizing behavior of organoids and gastruloids may pose a slight challenge to this novel ethical approach. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Data Sharing in Interpretive Engineering Education Research: Challenges and Opportunities from a Research Quality Perspective

    ERIC Educational Resources Information Center

    Walther, Joachim; Sochacka, Nicola W.; Pawley, Alice L.

    2016-01-01

    This article explores challenges and opportunities associated with sharing qualitative data in engineering education research. This exploration is theoretically informed by an existing framework of interpretive research quality with a focus on the concept of Communicative Validation. Drawing on practice anecdotes from the authors' work, the…

  5. Reversing the Trend of Engineering Enrollment Declines with Innovative Outreach, Recruiting, and Retention Programs

    ERIC Educational Resources Information Center

    Davis, C. E.; Yeary, M. B.; Sluss, J. J., Jr.

    2012-01-01

    This paper discusses an all-encompassing approach to increase the number of students in engineering through innovative outreach, recruiting, and retention programs. Prior to adopting these programs, the School of Electrical and Computer Engineering (ECE) at the University of Oklahoma (OU), Norman, experienced a reduction in engineering enrollment…

  6. The Science of Solubility: Using Reverse Engineering to Brew a Perfect Cup of Coffee

    ERIC Educational Resources Information Center

    West, Andrew B.; Sickel, Aaron J.; Cribbs, Jennifer D.

    2015-01-01

    The Next Generation Science Standards call for the integration of science and engineering. Often, the introduction of engineering activities occurs after instruction in the science content. That is, engineering is used as a way for students to elaborate on science ideas that have already been explored. However, using only this sequence of…

  7. The Science of Solubility: Using Reverse Engineering to Brew a Perfect Cup of Coffee

    ERIC Educational Resources Information Center

    West, Andrew B.; Sickel, Aaron J.; Cribbs, Jennifer D.

    2015-01-01

    The Next Generation Science Standards call for the integration of science and engineering. Often, the introduction of engineering activities occurs after instruction in the science content. That is, engineering is used as a way for students to elaborate on science ideas that have already been explored. However, using only this sequence of…

  8. Microvascular Guidance: A Challenge to Support the Development of Vascularised Tissue Engineering Construct

    PubMed Central

    Sukmana, Irza

    2012-01-01

    The guidance of endothelial cell organization into a capillary network has been a long-standing challenge in tissue engineering. Some research efforts have been made to develop methods to promote capillary networks inside engineered tissue constructs. Capillary and vascular networks that would mimic blood microvessel function can be used to subsequently facilitate oxygen and nutrient transfer as well as waste removal. Vascularization of engineering tissue construct is one of the most favorable strategies to overpass nutrient and oxygen supply limitation, which is often the major hurdle in developing thick and complex tissue and artificial organ. This paper addresses recent advances and future challenges in developing three-dimensional culture systems to promote tissue construct vascularization allowing mimicking blood microvessel development and function encountered in vivo. Bioreactors systems that have been used to create fully vascularized functional tissue constructs will also be outlined. PMID:22623881

  9. [Progress and challenges in tissue engineering of intervertebral disc annulus fibrosus].

    PubMed

    Zhou, Pinghui; Guo, Qianping; Ling, Feng; Qian, Zhonglai; Li, Bin

    2016-03-01

    Degenerative disc disease (DDD) is a leading cause of low back pain, which severely affects the quality of life and incurs significant medical cost. Annulus fibrosus(AF) injuries can lead to substantial deterioration of intervertebral disc degeneration. However, the AF repair/regeneration remains a challenge due to the intrinsic cellular, biochemical and biomechanical heterogeneity of AF tissue. Tissue engineering would be a promising approach for AF regeneration. This article aims to provide a brief overview of the fundamental aspects of AF, the current achievements and future challenges of AF tissue engineering. A multidisciplinary approach is proposed for future studies to fully mimic the native AF tissue and its microenvironment, including choosing adequate cell source, preparing scaffolds with hierarchical microstructures, supplementing appropriate growth factors, and enforcing suitable mechanical stimulation. Hopefully, the engineered AF tissues would be effectively used to facilitate the treatment of DDD in the future.

  10. Progress challenges and opportunities for the re-engineering of trans-AT polyketide synthases.

    PubMed

    Till, M; Race, P R

    2014-05-01

    Polyketides are a structurally and functionally diverse family of bioactive natural products that are used extensively as pharmaceuticals and agrochemicals. In bacteria these molecules are biosynthesized by giant, multi-functional enzymatic complexes, termed modular polyketide synthases (PKSs), that function in assembly-line like fashion to fuse and tailor simple carboxylic acid monomers into a vast array of elaborate chemical scaffolds. Modifying PKSs through targeted synthase re-engineering is a promising approach for accessing functionally-optimized polyketides. Due to their highly mosaic architectures the recently identified trans-AT family of modular synthases appear inherently more amenable to re-engineering than their well studied cis-AT counterparts. Here, we review recent progress in the re-engineering of trans-AT PKSs, summarize opportunities for harnessing the biosynthetic potential of these systems, and highlight challenges that such re-engineering approaches present.

  11. SSME to RS-25: Challenges of Adapting a Heritage Engine to a New Vehicle Architecture

    NASA Technical Reports Server (NTRS)

    Ballard, Richard O.

    2015-01-01

    A key constituent of the NASA Space Launch System (SLS) architecture is the RS-25 engine, also known as the Space Shuttle Main Engine (SSME). This engine was selected largely due to the maturity and extensive experience gained through 30-plus years of service. However, while the RS-25 is a highly mature system, simply unbolting it from the Space Shuttle and mounting it on the new SLS vehicle is not a "plug-and-play" operation. In addition to numerous technical integration and operational details, there were also hardware upgrades needed. While the magnitude of effort is less than that needed to develop a new clean-sheet engine system, this paper describes some of the expected and unexpected challenges encountered to date on the path to the first flight of SLS.

  12. Stereotype Threat: A Qualitative Study of the Challenges Facing Female Undergraduate Engineering Students

    NASA Astrophysics Data System (ADS)

    Entsminger, J. R., II

    From a sociocultural point of view, this qualitative case study explored how upper-level, female undergraduate engineering students perceived the possibility of or experience with stereotype threat as shaping their experiences. The study also investigated how these students explained their reasons for choosing their engineering major, the challenges they encountered in the major, and their reasons for persevering in spite of those challenges. Using Steele and Aronson's (1995) stereotype threat theory as a framework, and considering the documented underrepresentation of females in engineering, the study sought to examine how stereotype threat shaped the experiences of these students and if stereotype threat could be considered a valid reason for the underrepresentation. The study was conducted at a large, four-year public university. First, students in the College of Engineering and Engineering Technology completed the Participant Screening Survey. Based on responses from the survey, six female engineering students from the college were identified and invited to participate in the study. The participants came from the following majors: Electrical Engineering, Industrial and Systems Engineering, and Mechanical Engineering. After receiving the study consent letter and agreeing to participate, the students were involved in a 90-minute focus group meeting, a 45-minute one-on-one interview, and a 30-minute follow-up interview. After conducting the data collection methods, the data were then transcribed, analyzed, and coded for theme development. The themes that emerged coincided with each research question. The themes highlighted the complex interactions and experiences shared by the female engineering majors. The female students were enveloped in an environment where there existed an increased risk for activating stereotype threat. In addition, the female students described feeling pushed to prove to themselves and to others that the negative stereotype that 'females

  13. Reverse engineering and analysis of genome-wide gene regulatory networks from gene expression profiles using high-performance computing.

    PubMed

    Belcastro, Vincenzo; Gregoretti, Francesco; Siciliano, Velia; Santoro, Michele; D'Angelo, Giovanni; Oliva, Gennaro; di Bernardo, Diego

    2012-01-01

    Regulation of gene expression is a carefully regulated phenomenon in the cell. “Reverse-engineering” algorithms try to reconstruct the regulatory interactions among genes from genome-scale measurements of gene expression profiles (microarrays). Mammalian cells express tens of thousands of genes; hence, hundreds of gene expression profiles are necessary in order to have acceptable statistical evidence of interactions between genes. As the number of profiles to be analyzed increases, so do computational costs and memory requirements. In this work, we designed and developed a parallel computing algorithm to reverse-engineer genome-scale gene regulatory networks from thousands of gene expression profiles. The algorithm is based on computing pairwise Mutual Information between each gene-pair. We successfully tested it to reverse engineer the Mus Musculus (mouse) gene regulatory network in liver from gene expression profiles collected from a public repository. A parallel hierarchical clustering algorithm was implemented to discover “communities” within the gene network. Network communities are enriched for genes involved in the same biological functions. The inferred network was used to identify two mitochondrial proteins.

  14. Mars Reconnaissance Orbiter Mission: Systems Engineering Challenges on the Mars Reconnaissance Orbiter Mission

    NASA Technical Reports Server (NTRS)

    Havens, Glen G.

    2007-01-01

    MRO project is a system of systems requiring system engineering team to architect, design, integrate, test, and operate these systems at each level of the project. The challenge of system engineering mission objectives into a single mission architecture that can be integrated tested, launched, and operated. Systems engineering must translate high-level requirements into integrated mission design. Systems engineering challenges were overcome utilizing a combination by creative designs built into MRO's flight and ground systems: a) Design of sophisticated spacecraft targeting and data management capabilities b) Establishment of a strong operations team organization; c) Implementation of robust operational processes; and d) Development of strategic ground tools. The MRO system has met the challenge of its driving requirements: a) MRO began its two-year primary science phase on November 7, 2006, and by July 2007, met it minimum requirement to collect 15 Tbits of data after only eight months of operations. Currently we have collected 22 Tbits. b) Based on current performance, mission data return could return 70 Tbits of data by the end of the primary science phase in 2008.

  15. Mars Reconnaissance Orbiter Mission: Systems Engineering Challenges on the Mars Reconnaissance Orbiter Mission

    NASA Technical Reports Server (NTRS)

    Havens, Glen G.

    2007-01-01

    MRO project is a system of systems requiring system engineering team to architect, design, integrate, test, and operate these systems at each level of the project. The challenge of system engineering mission objectives into a single mission architecture that can be integrated tested, launched, and operated. Systems engineering must translate high-level requirements into integrated mission design. Systems engineering challenges were overcome utilizing a combination by creative designs built into MRO's flight and ground systems: a) Design of sophisticated spacecraft targeting and data management capabilities b) Establishment of a strong operations team organization; c) Implementation of robust operational processes; and d) Development of strategic ground tools. The MRO system has met the challenge of its driving requirements: a) MRO began its two-year primary science phase on November 7, 2006, and by July 2007, met it minimum requirement to collect 15 Tbits of data after only eight months of operations. Currently we have collected 22 Tbits. b) Based on current performance, mission data return could return 70 Tbits of data by the end of the primary science phase in 2008.

  16. The European Project Semester at ISEP: the challenge of educating global engineers

    NASA Astrophysics Data System (ADS)

    Malheiro, Benedita; Silva, Manuel; Ribeiro, Maria Cristina; Guedes, Pedro; Ferreira, Paulo

    2015-05-01

    Current engineering education challenges require approaches that promote scientific, technical, design and complementary skills while fostering autonomy, innovation and responsibility. The European Project Semester (EPS) at Instituto Superior de Engenharia do Porto (ISEP) (EPS@ISEP) is a one semester project-based learning programme (30 European Credit Transfer Units (ECTU)) for engineering students from diverse scientific backgrounds and nationalities that intends to address these goals. The students, organised in multidisciplinary and multicultural teams, are challenged to solve real multidisciplinary problems during one semester. The EPS package, although on project development (20 ECTU), includes a series of complementary seminars aimed at fostering soft, project-related and engineering transversal skills (10 ECTU). Hence, the students enrolled in this programme improve their transversal skills and learn, together and with the team of supervisors, subjects distinct from their core training. This paper presents the structure, implementation and results of the EPS@ISEP that was created in 2011 to apply the best engineering practices and promote internationalisation and engineering education innovation at ISEP.

  17. Analysis of the flow field generated near an aircraft engine operating in reverse thrust. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Ledwith, W. A., Jr.

    1972-01-01

    A computer solution is developed to the exhaust gas reingestion problem for aircraft operating in the reverse thrust mode on a crosswind-free runway. The computer program determines the location of the inlet flow pattern, whether the exhaust efflux lies within the inlet flow pattern or not, and if so, the approximate time before the reversed flow reaches the engine inlet. The program is written so that the user is free to select discrete runway speeds or to study the entire aircraft deceleration process for both the far field and cross-ingestion problems. While developed with STOL applications in mind, the solution is equally applicable to conventional designs. The inlet and reversed jet flow fields involved in the problem are assumed to be noninteracting. The nacelle model used in determining the inlet flow field is generated using an iterative solution to the Neuman problem from potential flow theory while the reversed jet flow field is adapted using an empirical correlation from the literature. Sample results obtained using the program are included.

  18. Tissue Engineering and Regenerative Medicine: The Promise, the Challenges, the Future.

    PubMed

    Mertz, Leslie

    2017-01-01

    Medical researchers increasingly regard tissue engineering and regenerative medicine as potential game changers when it comes to repairing damage from disease or injury and restoring function. To understand the progress made and challenges ahead for this combined field, IEEE Pulse sought out two experts: David F. Williams, former global president (2012-2015) of the Tissue Engineering and Regenerative Medicine International Society, and Roderic I. Pettigrew, founding director of the National Institute of Biomedical Imaging and Bioengineering (NIBIB) at the National Institutes of Health (NIH) [1].

  19. Engines/Fuels Workshop, 6-8 December 1982, San Antonio, Texas.

    DTIC Science & Technology

    1982-01-01

    different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse side if necessary and identify by block number) Diesel Fuel Gas Turbine...Engine Fuel Diesel Engine Combustion Gas Turbine Engine Combustion Diesel Engines Gas Turbine Engines Adiabatic Diesel Engine Multifuel Engines...compound adiabatic diesel , provide promise for real efficiency gains but also provide challenges for combustion optimization. At this workshop

  20. Novel thrombin and factor Xa inhibitors: challenges to reversal of their anticoagulation effects.

    PubMed

    Yates, Sean; Sarode, Ravi

    2013-11-01

    Warfarin has been the sole oral anticoagulant used in the management of thromboembolic disorders for over 60 years. Target-specific oral anticoagulants (TSOAs) have recently emerged as alternatives to warfarin, because they do not require laboratory monitoring. Nevertheless, with the rising use of TSOAs, there is growing concern among clinicians regarding management of bleeding in patients taking them. Unlike warfarin, there is no antidote or reversal agent for TSOAs. This review summarizes recent developments and attempts to provide a systematic approach to patients on TSOAs presenting with bleeding complications. Currently, data involving clinical management of TSOAs are limited and primarily based on ex-vivo or animal models using hemostatic agents with uncertain implications in bleeding patients. There is a pressing need for randomized clinical trials evaluating the safety and efficacy of hemostatic agents. Without evidence-based guidelines for TSOA management, appropriate patient care requires an understanding of TSOA pharmacology, their effect on coagulation tests and, hence, a correct interpretation of test results, as well as a systematic approach to bleeding complications.

  1. Systems engineering medicine: engineering the inflammation response to infectious and traumatic challenges

    PubMed Central

    Parker, Robert S.; Clermont, Gilles

    2010-01-01

    The complexity of the systemic inflammatory response and the lack of a treatment breakthrough in the treatment of pathogenic infection demand that advanced tools be brought to bear in the treatment of severe sepsis and trauma. Systems medicine, the translational science counterpart to basic science's systems biology, is the interface at which these tools may be constructed. Rapid initial strides in improving sepsis treatment are possible through the use of phenomenological modelling and optimization tools for process understanding and device design. Higher impact, and more generalizable, treatment designs are based on mechanistic understanding developed through the use of physiologically based models, characterization of population variability, and the use of control-theoretic systems engineering concepts. In this review we introduce acute inflammation and sepsis as an example of just one area that is currently underserved by the systems medicine community, and, therefore, an area in which contributions of all types can be made. PMID:20147315

  2. Systems engineering medicine: engineering the inflammation response to infectious and traumatic challenges.

    PubMed

    Parker, Robert S; Clermont, Gilles

    2010-07-06

    The complexity of the systemic inflammatory response and the lack of a treatment breakthrough in the treatment of pathogenic infection demand that advanced tools be brought to bear in the treatment of severe sepsis and trauma. Systems medicine, the translational science counterpart to basic science's systems biology, is the interface at which these tools may be constructed. Rapid initial strides in improving sepsis treatment are possible through the use of phenomenological modelling and optimization tools for process understanding and device design. Higher impact, and more generalizable, treatment designs are based on mechanistic understanding developed through the use of physiologically based models, characterization of population variability, and the use of control-theoretic systems engineering concepts. In this review we introduce acute inflammation and sepsis as an example of just one area that is currently underserved by the systems medicine community, and, therefore, an area in which contributions of all types can be made.

  3. Reverse engineering of an affinity-switchable molecular interaction characterized by atomic force microscopy single-molecule force spectroscopy.

    PubMed

    Anselmetti, Dario; Bartels, Frank Wilco; Becker, Anke; Decker, Björn; Eckel, Rainer; McIntosh, Matthew; Mattay, Jochen; Plattner, Patrik; Ros, Robert; Schäfer, Christian; Sewald, Norbert

    2008-02-19

    Tunable and switchable interaction between molecules is a key for regulation and control of cellular processes. The translation of the underlying physicochemical principles to synthetic and switchable functional entities and molecules that can mimic the corresponding molecular functions is called reverse molecular engineering. We quantitatively investigated autoinducer-regulated DNA-protein interaction in bacterial gene regulation processes with single atomic force microscopy (AFM) molecule force spectroscopy in vitro, and developed an artificial bistable molecular host-guest system that can be controlled and regulated by external signals (UV light exposure and thermal energy). The intermolecular binding functionality (affinity) and its reproducible and reversible switching has been proven by AFM force spectroscopy at the single-molecule level. This affinity-tunable optomechanical switch will allow novel applications with respect to molecular manipulation, nanoscale rewritable molecular memories, and/or artificial ion channels, which will serve for the controlled transport and release of ions and neutral compounds in the future.

  4. Engineered skeletal muscle tissue for soft robotics: fabrication strategies, current applications, and future challenges.

    PubMed

    Duffy, Rebecca M; Feinberg, Adam W

    2014-01-01

    Skeletal muscle is a scalable actuator system used throughout nature from the millimeter to meter length scales and over a wide range of frequencies and force regimes. This adaptability has spurred interest in using engineered skeletal muscle to power soft robotics devices and in biotechnology and medical applications. However, the challenges to doing this are similar to those facing the tissue engineering and regenerative medicine fields; specifically, how do we translate our understanding of myogenesis in vivo to the engineering of muscle constructs in vitro to achieve functional integration with devices. To do this researchers are developing a number of ways to engineer the cellular microenvironment to guide skeletal muscle tissue formation. This includes understanding the role of substrate stiffness and the mechanical environment, engineering the spatial organization of biochemical and physical cues to guide muscle alignment, and developing bioreactors for mechanical and electrical conditioning. Examples of engineered skeletal muscle that can potentially be used in soft robotics include 2D cantilever-based skeletal muscle actuators and 3D skeletal muscle tissues engineered using scaffolds or directed self-organization. Integration into devices has led to basic muscle-powered devices such as grippers and pumps as well as more sophisticated muscle-powered soft robots that walk and swim. Looking forward, current, and future challenges include identifying the best source of muscle precursor cells to expand and differentiate into myotubes, replacing cardiomyocytes with skeletal muscle tissue as the bio-actuator of choice for soft robots, and vascularization and innervation to enable control and nourishment of larger muscle tissue constructs. © 2013 Wiley Periodicals, Inc.

  5. From Zero to Integration in Eight Months, the Dawn Ground Data System Engineering Challenge

    NASA Technical Reports Server (NTRS)

    Dubon, Lydia P.

    2006-01-01

    The Dawn GDS Team met the SC Sim integration challenge in eight months. The GDS System Engineering approach in response to the SC Simintegration challenge, focused on a set of key practices: decomposition of project request into manageable requirements; integration of multiple ground disciplines and experts into a focused team effort; risk management thru management of expectations; and aggregation of intermediate products into a final product. By maintaining a a system-level focus, the overall systems engineering process unified team GDS Team members with a common goal: the success of the ground system as a whole and not just the success of their individual expert contributions. Incorporation of Agile-type development efforts were aligned with a risk strategy based on team-oriented principles and expectations management, thus achieving a more stable baseline solution without compromising the integrity of the GDS design.

  6. From Zero to Integration in Eight Months, the Dawn Ground Data System Engineering Challenge

    NASA Technical Reports Server (NTRS)

    Dubon, Lydia P.

    2006-01-01

    The Dawn GDS Team met the SC Sim integration challenge in eight months. The GDS System Engineering approach in response to the SC Simintegration challenge, focused on a set of key practices: decomposition of project request into manageable requirements; integration of multiple ground disciplines and experts into a focused team effort; risk management thru management of expectations; and aggregation of intermediate products into a final product. By maintaining a a system-level focus, the overall systems engineering process unified team GDS Team members with a common goal: the success of the ground system as a whole and not just the success of their individual expert contributions. Incorporation of Agile-type development efforts were aligned with a risk strategy based on team-oriented principles and expectations management, thus achieving a more stable baseline solution without compromising the integrity of the GDS design.

  7. Tissue engineering strategies in spinal arthrodesis: the clinical imperative and challenges to clinical translation.

    PubMed

    Evans, Nick R; Davies, Evan M; Dare, Chris J; Oreffo, Richard Oc

    2013-01-01

    Skeletal disorders requiring the regeneration or de novo production of bone present considerable reconstructive challenges and are one of the main driving forces for the development of skeletal tissue engineering strategies. The skeletal or mesenchymal stem cell is a fundamental requirement for osteogenesis and plays a pivotal role in the design and application of these strategies. Research activity has focused on incorporating the biological role of the mesenchymal stem cell with the developing fields of material science and gene therapy in order to create a construct that is not only capable of inducing host osteoblasts to produce bone, but is also osteogenic in its own right. This review explores the clinical need for reparative approaches in spinal arthrodesis, identifying recent tissue engineering strategies employed to promote spinal fusion, and considers the ongoing challenges to successful clinical translation.

  8. Recent advances in the engineering of nanosized active pharmaceutical ingredients: Promises and challenges.

    PubMed

    Kaialy, Waseem; Al Shafiee, Maen

    2016-02-01

    The advances in the field of nanotechnology have revolutionized the field of delivery of poorly soluble active pharmaceutical ingredients (APIs). Nanosized formulations have been extensively investigated to achieve a rapid dissolution and therefore pharmacokinetic properties similar to those observed in solutions. The present review outlines the recent advances, promises and challenges of the engineering nanosized APIs. The principles, merits, demerits and applications of the current 'bottom-up' and 'top-down' technologies by which the state of the art nanosized APIs can be produced were described. Although the number of research reports on the nanoparticle engineering topic has been growing in the last decade, the challenge is to take numerous research outcomes and convert them into strategies for the development of marketable products.

  9. Transformation of engineering education: Taking a perspective for the challenges of change

    NASA Astrophysics Data System (ADS)

    Siddiqui, Junaid Abdul Wahid

    There are a variety of imperatives which call us to transform engineering education. Those who have made attempts to facilitate a change in engineering education have experienced slow or no progress. The literature on change has suggestions and strategies related to educational change but most of them are not able to guide the conversations and actions effectively. People interested in understanding the challenges often ask 'what makes educational change so difficult?' This research is an effort towards finding an answer to this question. The study adopted a transdisciplinary approach while taking a systems perspective on educational change in order to examine the challenges. Instead of exploring the effectiveness of change strategies and interventions, this study sought to understand the basic nature of change in engineering education organizations. For this purpose, the study adopted an integrated theoretical framework consisting of systems thinking, complexity theory, and transformative learning theory. The methodology was designed on the complexity research paradigm with interpretive qualitative methods used for data analysis. This approach enabled understanding the social and human conditions which reduce or enhance the likelihood of change in the context of an engineering education organization. The context for this study to investigate the challenges of transformation in engineering education is efforts around educating the Engineer of 2020. Four institutional initiatives at various stages in the transformation process provided cases for investigation in the study. The engineering educators at the four institutions participating in the study had experiences of active engagement in educational change. The interpretive qualitative analysis of the participants' accounts induced a systems perspective of the challenges which faculty face in their educational transformation efforts. The inertia which educational organizations experience against change appears to

  10. A Geodynamic Grand Challenge: Time-Reversed Mantle Convection Reconstructions From Tomographic Images of Present-Day Mantle Structure

    NASA Astrophysics Data System (ADS)

    Glisovic, P.; Forte, A. M.; Moucha, R.

    2009-12-01

    One of the most complex challenges in current geodynamics research is the reconstruction of the past evolution of 3-D mantle temperature structure from seismic tomographic images of present-day lateral heterogeneity in the mantle. Early efforts to address this problem have been based on backward advection approximations based on the assumption that mantle convection is a very-high Rayleigh number process (e.g. Forte & Mitrovica 1997; Steinberger & O'Connell 1997). Over the past decade further progress has been achieved and new techniques have been proposed, such as the 4-D variational (Bunge et al. 2003) and quasi-reversible (Ismail-Zadeh et al. 2007) approaches. An enduring challenge is the construction of time-reversed mantle convection simulations that yield maximum consistency with a wide suite of surface geodynamic constraints on mantle rheology and 3-D structure inferred from seismic tomography. Resolving this outstanding problem is of crucial importance, because a successful reconstruction of the time-dependent, 3-D mantle convective structure in the geological past provides unique insights into the origin and evolution of a number of fundamental surface processes that include topography changes, eustatic sea level variations, state of stress in the lithosphere, and Earth rotation variations. A key concern in these reconstructions is quantifying the inherent uncertainties and the implications for surface geodynamic observables. We will explore these issues and compare the efficacy of different backward convection techniques using a new mantle convection model based on recent joint seismic-geodynamic tomography inversions (Simmons et al., GJI, 2009).

  11. The significance of cell-related challenges in the clinical application of tissue engineering.

    PubMed

    Almela, Thafar; Brook, Ian M; Moharamzadeh, Keyvan

    2016-12-01

    Tissue engineering is increasingly being recognized as a new approach that could alleviate the burden of tissue damage currently managed with transplants or synthetic devices. Making this novel approach available in the future for patients who would potentially benefit is largely dependent on understanding and addressing all those factors that impede the translation of this technology to the clinic. Cell-associated factors in particular raise many challenges, including those related to cell sources, up- and downstream techniques, preservation, and the creation of in vitro microenvironments that enable cells to grow and function as far as possible as they would in vivo. This article highlights the main confounding issues associated with cells in tissue engineering and how these issues may hinder the advancement of therapeutic tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3157-3163, 2016. © 2016 Wiley Periodicals, Inc.

  12. SSME to RS-25: Challenges of Adapting a Heritage Engine to a New Vehicle Architecture

    NASA Technical Reports Server (NTRS)

    Ballard, Richard O.

    2015-01-01

    Following the cancellation of the Constellation program and retirement of the Space Shuttle, NASA initiated the Space Launch System (SLS) program to provide next-generation heavy lift cargo and crew access to space. A key constituent of the SLS architecture is the RS-25 engine, also known as the Space Shuttle Main Engine (SSME). The RS-25 was selected to serve as the main propulsion system for the SLS core stage in conjunction with the solid rocket boosters. This selection was largely based on the maturity and extensive experience gained through 135 missions, 3000+ ground tests, and over a million seconds total accumulated hot-fire time. In addition, there were also over a dozen functional flight assets remaining from the Space Shuttle program that could be leveraged to support the first four flights. However, while the RS-25 is a highly mature system, simply unbolting it from the Space Shuttle boat-tail and installing it on the new SLS vehicle is not a "plug-and-play" operation. In addition to numerous technical integration details involving changes to significant areas such as the environments, interface conditions, technical performance requirements, operational constraints and so on, there were other challenges to be overcome in the area of replacing the obsolete engine control system (ECS). While the magnitude of accomplishing this effort was less than that needed to develop and field a new clean-sheet engine system, the path to the first flight of SLS has not been without unexpected challenges.

  13. Combustion-engine Temperatures by the Sodium Line-reversal Method

    NASA Technical Reports Server (NTRS)

    Brevoort, Maurice J

    1936-01-01

    The sodium line-reversal method has been used in some preliminary measurements of flame temperature. Improvements in the method involving a photographic recorder and a means of correcting for the dirtiness of the windows are described. The temperatures so obtained are compared with those calculated from pressure diagrams.

  14. Engineering metal complexes of chiral pentaazacrowns as privileged reverse-turn scaffolds.

    PubMed

    Che, Ye; Brooks, Bernard R; Riley, Dennis P; Reaka, Andrea J H; Marshall, Garland R

    2007-02-01

    Reverse turns are common structural motifs and recognition sites in protein/protein interactions. The design of peptidomimetics is often based on replacing the amide backbone of peptides by a non-peptidic scaffold while retaining the biologic mode of action. This study evaluates the potential of metal complexes of chiral pentaazacrowns conceptually derived by reduction of cyclic pentapeptides as reverse-turn mimetics. The possible conformations of metal complexes of chiral pentaazacrown scaffolds have been probed by analysis of 28 crystal structures complexed with six different metals (Mn, Fe, Co, Ni, Cu, and Zn). The solvated structures as well as the impact of complexation with different metals/oxidation states have been examined with density functional theory (DFT) calculation as explicitly represented by interactions with a single water molecule. The results suggest that most reverse-turn motifs seen in proteins could be mimicked effectively with a subset of metal complexes of chiral pentaazacrown scaffolds with an RMSD of approximately 0.3 A. Due to the relatively fixed orientation of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor-bound conformation of the parent peptide from their binding affinities. The presence of 20 H-atoms on the pentaazacrown ring that could be functionalized as well as the conformational perturbations available from complexation with different metals offer a desirable diversity to probe receptors for reverse-turn recognition.

  15. Industrial Adoption of Model-Based Systems Engineering: Challenges and Strategies

    NASA Astrophysics Data System (ADS)

    Maheshwari, Apoorv

    As design teams are becoming more globally integrated, one of the biggest challenges is to efficiently communicate across the team. The increasing complexity and multi-disciplinary nature of the products are also making it difficult to keep track of all the information generated during the design process by these global team members. System engineers have identified Model-based Systems Engineering (MBSE) as a possible solution where the emphasis is placed on the application of visual modeling methods and best practices to systems engineering (SE) activities right from the beginning of the conceptual design phases through to the end of the product lifecycle. Despite several advantages, there are multiple challenges restricting the adoption of MBSE by industry. We mainly consider the following two challenges: a) Industry perceives MBSE just as a diagramming tool and does not see too much value in MBSE; b) Industrial adopters are skeptical if the products developed using MBSE approach will be accepted by the regulatory bodies. To provide counter evidence to the former challenge, we developed a generic framework for translation from an MBSE tool (Systems Modeling Language, SysML) to an analysis tool (Agent-Based Modeling, ABM). The translation is demonstrated using a simplified air traffic management problem and provides an example of a potential quite significant value: the ability to use MBSE representations directly in an analysis setting. For the latter challenge, we are developing a reference model that uses SysML to represent a generic infusion pump and SE process for planning, developing, and obtaining regulatory approval of a medical device. This reference model demonstrates how regulatory requirements can be captured effectively through model-based representations. We will present another case study at the end where we will apply the knowledge gained from both case studies to a UAV design problem.

  16. Virtual reality surgical planning for maxillofacial distraction osteogenesis: the role of reverse engineering rapid prototyping and cooperative work.

    PubMed

    Robiony, Massimo; Salvo, Iolanda; Costa, Fabio; Zerman, Nicoletta; Bazzocchi, Massimo; Toso, Francesco; Bandera, Camillo; Filippi, Stefano; Felice, Martina; Politi, Massimo

    2007-06-01

    The purpose of this article is the demonstration of virtual reality (VR) and rapid prototyping (RP) in surgical planning in maxillofacial surgery. The authors emphasize the role of reverse engineering (RE) and RP, suggesting a model of cooperative work, with the interaction of maxillofacial surgeons, radiologists, and engineers. Data acquisition is performed using computed tomography. The 3D model is the result of RE practices based on image segmentation, and the real model is produced via stereolithography. Virtual simulations are performed on the 3D model obtained from image segmentation. All these stages require the interaction and collaboration of various experts: maxillofacial surgeons, radiologists, and RE and RP experts. VR and stereolithography models represent a new technology to help the surgeon who has to work in cooperation with engineers and radiologists to improve the results in surgical planning of maxillofacial distraction. When performing the VR simulation, surgeons and engineers operate together in order to optimize the exploitation of the instruments available. Both VR and RP, with different and complementary advantages and limitations, can improve surgical planning activities and this is particularly effective when dealing with complex anatomical structures in maxillofacial surgery.

  17. Arabidopsis Ensemble Reverse-Engineered Gene Regulatory Network Discloses Interconnected Transcription Factors in Oxidative Stress[W

    PubMed Central

    Vermeirssen, Vanessa; De Clercq, Inge; Van Parys, Thomas; Van Breusegem, Frank; Van de Peer, Yves

    2014-01-01

    The abiotic stress response in plants is complex and tightly controlled by gene regulation. We present an abiotic stress gene regulatory network of 200,014 interactions for 11,938 target genes by integrating four complementary reverse-engineering solutions through average rank aggregation on an Arabidopsis thaliana microarray expression compendium. This ensemble performed the most robustly in benchmarking and greatly expands upon the availability of interactions currently reported. Besides recovering 1182 known regulatory interactions, cis-regulatory motifs and coherent functionalities of target genes corresponded with the predicted transcription factors. We provide a valuable resource of 572 abiotic stress modules of coregulated genes with functional and regulatory information, from which we deduced functional relationships for 1966 uncharacterized genes and many regulators. Using gain- and loss-of-function mutants of seven transcription factors grown under control and salt stress conditions, we experimentally validated 141 out of 271 predictions (52% precision) for 102 selected genes and mapped 148 additional transcription factor-gene regulatory interactions (49% recall). We identified an intricate core oxidative stress regulatory network where NAC13, NAC053, ERF6, WRKY6, and NAC032 transcription factors interconnect and function in detoxification. Our work shows that ensemble reverse-engineering can generate robust biological hypotheses of gene regulation in a multicellular eukaryote that can be tested by medium-throughput experimental validation. PMID:25549671

  18. Reverse-engineering the genetic circuitry of a cancer cell with predicted intervention in chronic lymphocytic leukemia.

    PubMed

    Vallat, Laurent; Kemper, Corey A; Jung, Nicolas; Maumy-Bertrand, Myriam; Bertrand, Frédéric; Meyer, Nicolas; Pocheville, Arnaud; Fisher, John W; Gribben, John G; Bahram, Seiamak

    2013-01-08

    Cellular behavior is sustained by genetic programs that are progressively disrupted in pathological conditions--notably, cancer. High-throughput gene expression profiling has been used to infer statistical models describing these cellular programs, and development is now needed to guide orientated modulation of these systems. Here we develop a regression-based model to reverse-engineer a temporal genetic program, based on relevant patterns of gene expression after cell stimulation. This method integrates the temporal dimension of biological rewiring of genetic programs and enables the prediction of the effect of targeted gene disruption at the system level. We tested the performance accuracy of this model on synthetic data before reverse-engineering the response of primary cancer cells to a proliferative (protumorigenic) stimulation in a multistate leukemia biological model (i.e., chronic lymphocytic leukemia). To validate the ability of our method to predict the effects of gene modulation on the global program, we performed an intervention experiment on a targeted gene. Comparison of the predicted and observed gene expression changes demonstrates the possibility of predicting the effects of a perturbation in a gene regulatory network, a first step toward an orientated intervention in a cancer cell genetic program.

  19. Finite element and wavefront error analysis of the primary mirror of an experimental telescope with reverse engineering

    NASA Astrophysics Data System (ADS)

    Huang, Bo-Kai; Huang, Po-Hsuan

    2016-09-01

    This paper presents the finite element and wavefront error analysis with reverse engineering of the primary mirror of a small space telescope experimental model. The experimental space telescope with 280mm diameter primary mirror has been assembled and aligned in 2011, but the measured system optical performance and wavefront error did not achieve the goal. In order to find out the root causes, static structure finite element analysis (FEA) has been applied to analyze the structure model of the primary mirror assembly. Several assuming effects which may cause deformation of the primary mirror have been proposed, such as gravity effect, flexures bonding effect, thermal expansion effect, etc. According to each assuming effect, we establish a corresponding model and boundary condition setup, and the numerical model will be analyzed by finite element method (FEM) software and opto-mechanical analysis software to obtain numerical wavefront error and Zernike polynomials. Now new assumption of the flexures bonding effect is proposed, and we adopt reverse engineering to verify this effect. Finally, the numerically synthetic system wavefront error will be compared with measured system wavefront error of the telescope. By analyzing and realizing these deformation effects of the primary mirror, the opto-mechanical design and telescope assembly workmanship will be refined, and improve the telescope optical performance.

  20. Reverse-engineering the genetic circuitry of a cancer cell with predicted intervention in chronic lymphocytic leukemia

    PubMed Central

    Vallat, Laurent; Kemper, Corey A.; Jung, Nicolas; Maumy-Bertrand, Myriam; Bertrand, Frédéric; Meyer, Nicolas; Pocheville, Arnaud; Fisher, John W.; Gribben, John G.; Bahram, Seiamak

    2013-01-01

    Cellular behavior is sustained by genetic programs that are progressively disrupted in pathological conditions—notably, cancer. High-throughput gene expression profiling has been used to infer statistical models describing these cellular programs, and development is now needed to guide orientated modulation of these systems. Here we develop a regression-based model to reverse-engineer a temporal genetic program, based on relevant patterns of gene expression after cell stimulation. This method integrates the temporal dimension of biological rewiring of genetic programs and enables the prediction of the effect of targeted gene disruption at the system level. We tested the performance accuracy of this model on synthetic data before reverse-engineering the response of primary cancer cells to a proliferative (protumorigenic) stimulation in a multistate leukemia biological model (i.e., chronic lymphocytic leukemia). To validate the ability of our method to predict the effects of gene modulation on the global program, we performed an intervention experiment on a targeted gene. Comparison of the predicted and observed gene expression changes demonstrates the possibility of predicting the effects of a perturbation in a gene regulatory network, a first step toward an orientated intervention in a cancer cell genetic program. PMID:23267079

  1. Reverse engineering a mouse embryonic stem cell-specific transcriptional network reveals a new modulator of neuronal differentiation.

    PubMed

    De Cegli, Rossella; Iacobacci, Simona; Flore, Gemma; Gambardella, Gennaro; Mao, Lei; Cutillo, Luisa; Lauria, Mario; Klose, Joachim; Illingworth, Elizabeth; Banfi, Sandro; di Bernardo, Diego

    2013-01-01

    Gene expression profiles can be used to infer previously unknown transcriptional regulatory interaction among thousands of genes, via systems biology 'reverse engineering' approaches. We 'reverse engineered' an embryonic stem (ES)-specific transcriptional network from 171 gene expression profiles, measured in ES cells, to identify master regulators of gene expression ('hubs'). We discovered that E130012A19Rik (E13), highly expressed in mouse ES cells as compared with differentiated cells, was a central 'hub' of the network. We demonstrated that E13 is a protein-coding gene implicated in regulating the commitment towards the different neuronal subtypes and glia cells. The overexpression and knock-down of E13 in ES cell lines, undergoing differentiation into neurons and glia cells, caused a strong up-regulation of the glutamatergic neurons marker Vglut2 and a strong down-regulation of the GABAergic neurons marker GAD65 and of the radial glia marker Blbp. We confirmed E13 expression in the cerebral cortex of adult mice and during development. By immuno-based affinity purification, we characterized protein partners of E13, involved in the Polycomb complex. Our results suggest a role of E13 in regulating the division between glutamatergic projection neurons and GABAergic interneurons and glia cells possibly by epigenetic-mediated transcriptional regulation.

  2. Challenges in engineering osteochondral tissue grafts with hierarchical structures Ivana Gadjanski, Gordana Vunjak Novakovic

    PubMed Central

    Gadjanski, Ivana; Vunjak-Novakovic, Gordana

    2015-01-01

    Introduction A major hurdle in treating osteochondral (OC) defects are the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct-engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. Areas covered This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. Expert opinion A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens, and harnessing of inflammatory responses of the host will likely drive the further progress. PMID:26195329

  3. Fuel from Bacteria, CO2, Water, and Solar Energy: Engineering a Bacterial Reverse Fuel Cell

    SciTech Connect

    2010-07-01

    Electrofuels Project: Harvard is engineering a self-contained, scalable Electrofuels production system that can directly generate liquid fuels from bacteria, carbon dioxide (CO2), water, and sunlight. Harvard is genetically engineering bacteria called Shewanella, so the bacteria can sit directly on electrical conductors and absorb electrical current. This current, which is powered by solar panels, gives the bacteria the energy they need to process CO2 into liquid fuels. The Harvard team pumps this CO2 into the system, in addition to water and other nutrients needed to grow the bacteria. Harvard is also engineering the bacteria to produce fuel molecules that have properties similar to gasoline or diesel fuel—making them easier to incorporate into the existing fuel infrastructure. These molecules are designed to spontaneously separate from the water-based culture that the bacteria live in and to be used directly as fuel without further chemical processing once they’re pumped out of the tank.

  4. Reverse-Phase Microarray Analysis Reveals Novel Targets in Lymph Nodes of Bacillus anthracis Spore-Challenged Mice

    PubMed Central

    Popova, Taissia G.; Espina, Virginia; Liotta, Lance A.; Popov, Serguei G.

    2015-01-01

    Anthrax is a frequently fatal infection of many animal species and men. The causative agent Bacillus anthracis propagates through the lymphatic system of the infected host; however, the specific interactions of the host and microbe within the lymphatics are incompletely understood. We report the first description of the phosphoprotein signaling in the lymph nodes of DBA/2 mice using a novel technique combining the reverse-phase microarray with the laser capture microdissesction. Mice were challenged into foot pads with spores of toxinogenic, unencapsulated Sterne strain. The spores quickly migrated to the regional popliteal lymph nodes and spread to the bloodstream as early as 3 h post challenge. All mice died before 72 h post challenge from the systemic disease accompanied by a widespread LN tissue damage by bacteria, including the hemorrhagic necrotizing lymphadenitis, infiltration of CD11b+ and CD3+ cells, and massive proliferation of bacteria in lymph nodes. A macrophage scavenger receptor CD68/macrosialin was upregulated and found in association with vegetative bacteria likely as a marker of their prior interaction with macrophages. The major signaling findings among the 65 tested proteins included the reduced MAPK signaling, upregulation of STAT transcriptional factors, and altered abundance of a number of pro- and anti-apoptotic proteins with signaling properties opposing each other. Downregulation of ERK1/2 was associated with the response of CD11b+ macrophages/dendritic cells, while upregulation of the pro-apoptotic Puma indicated a targeting of CD3+ T-cells. A robust upregulation of the anti-apoptotic survivin was unexpected because generally it is not observed in adult tissues. Taken together with the activation of STATs it may reflect a new pathogenic mechanism aimed to delay the onset of apoptosis. Our data emphasize a notion that the net biological outcome of disease is determined by a cumulative impact of factors representing the microbial insult and

  5. Reverse-Phase Microarray Analysis Reveals Novel Targets in Lymph Nodes of Bacillus anthracis Spore-Challenged Mice.

    PubMed

    Popova, Taissia G; Espina, Virginia; Liotta, Lance A; Popov, Serguei G

    2015-01-01

    Anthrax is a frequently fatal infection of many animal species and men. The causative agent Bacillus anthracis propagates through the lymphatic system of the infected host; however, the specific interactions of the host and microbe within the lymphatics are incompletely understood. We report the first description of the phosphoprotein signaling in the lymph nodes of DBA/2 mice using a novel technique combining the reverse-phase microarray with the laser capture microdissection. Mice were challenged into foot pads with spores of toxinogenic, unencapsulated Sterne strain. The spores quickly migrated to the regional popliteal lymph nodes and spread to the bloodstream as early as 3 h post challenge. All mice died before 72 h post challenge from the systemic disease accompanied by a widespread LN tissue damage by bacteria, including the hemorrhagic necrotizing lymphadenitis, infiltration of CD11b+ and CD3+ cells, and massive proliferation of bacteria in lymph nodes. A macrophage scavenger receptor CD68/macrosialin was upregulated and found in association with vegetative bacteria likely as a marker of their prior interaction with macrophages. The major signaling findings among the 65 tested proteins included the reduced MAPK signaling, upregulation of STAT transcriptional factors, and altered abundance of a number of pro- and anti-apoptotic proteins with signaling properties opposing each other. Downregulation of ERK1/2 was associated with the response of CD11b+ macrophages/dendritic cells, while upregulation of the pro-apoptotic Puma indicated a targeting of CD3+ T-cells. A robust upregulation of the anti-apoptotic survivin was unexpected because generally it is not observed in adult tissues. Taken together with the activation of STATs it may reflect a new pathogenic mechanism aimed to delay the onset of apoptosis. Our data emphasize a notion that the net biological outcome of disease is determined by a cumulative impact of factors representing the microbial insult and

  6. Polar Engineering and Research to Address Operational Challenges in Austere Environments

    NASA Astrophysics Data System (ADS)

    Mercer, J. L.; Richter-Menge, J.; Weale, J. C.; Lever, J. H.; Knuth, M. A.; Shoop, S. A.; Haehnel, R.; Arcone, S. A.; Bjella, K.; Finnegan, D. C.; Courville, Z.; Tracy, B. T.

    2009-12-01

    Logistics constraints and operational challenges in the austere environs of the polar regions present unique technological and engineering problems. Working closely with universities, government agencies and industry, the U.S. Army Corps of Engineers Cold Regions Research and Engineering Lab (CRREL) routinely conducts scientific research and engineering in the Arctic, sub-Arctic and Antarctic covering a wide range of topics and applications. Current areas of focus include: improved mobility techniques for overland traverses; robotic vehicles for traversing, sampling and data collection; snow road and transportation characterization; integrated operational systems including airfield consolidation proof-of-concept studies; infrastructure technology such as firn air cooling, building design, snow foundations and sewage handling; remote/renewable autonomous power solutions for data collection; subsurface radar for crevasse detection and cryosphere characterization; ground-based lidar topographic scanning and near-real-time climate/environmental monitoring linked to AIS infrastructure. While these research and engineering efforts provide solutions and improved technology for specific problems, the impacts are many and wide-reaching and the results are often applicable to other challenging environments. Here, an overview of current research foci and projects is presented along with in-the-field applications, effects and future implications. The results and solutions of these efforts typically lead to technological improvements in operations and logistics which are cost-beneficial, thus freeing up funding dollars for fundamental scientific research. The links between basic research and applied solutions delivering far-reaching impacts (both large- and small-scale) on society, the environment, industry and scientific research are also demonstrated.

  7. Effect of lipophilic tail architecture and solvent engineering on the structure of trehalose-based nonionic surfactant reverse micelles.

    PubMed

    Shrestha, Lok Kumar; Sato, Takaaki; Dulle, Martin; Glatter, Otto; Aramaki, Kenji

    2010-09-23

    We use small-angle X-ray scattering and dynamic light scattering to investigate the structural and dynamical properties of trehalose polyisostearate, abbreviated as TQ-n (n = 3, 5, and 7), in different organic solvents, where n represents the number of isosterate chains per surfactant molecule. TQ-n spontaneously assembles into reverse micelles without addition of water at 25 °C. We found that for TQ-5 and TQ-7, steric hindrance of the lipophilic surfactant tail causes significant reduction of the aggregation number, whose scheme is clearly distinguished from the modification of the critical packing parameter. Increasing the hydrocarbon chain length of oils from octane to hexadecane favors one-dimensional micellar growth, leading to the formation of rodlike micelles due to different penetration tendencies of oils into the lipophilic shell of the surfactant. Subtle differences in solvent polarity also plays a crucial role in the micellar size, which is decreased when liquid paraffin is replaced with squalene. A further decrease is attained in more polar mixed triglyceride oils. A rising temperature also results in the same direction. The extrapolated structure factor to the zero scattering vector, S(q → 0), for the TQ-3/decane systems almost exactly follows that predicted for hard spheres, demonstrating that osmotic compressibility of the system is well explained if accounting for the excluded volume. However, we found that the effective diffusion coefficient decreases with surfactant concentration, which is an opposite trend to what is expected for hard spheres. This apparent contradiction is likely to be due to the occurrence of transient interdigitation between the lipophilic tails of neighboring reverse micelles at higher concentration. Our data highlight the relevance of the concept of "tunable reverse micellar geometry" in the novel trehalose-based nonionic surfactant binary mixtures, in which lipophilic tail architecture, solvent engineering, concentration

  8. Challenges of Engineering Grain Boundaries in Boron-Based Armor Ceramics

    NASA Astrophysics Data System (ADS)

    Coleman, Shawn P.; Hernandez-Rivera, Efrain; Behler, Kristopher D.; Synowczynski-Dunn, Jennifer; Tschopp, Mark A.

    2016-06-01

    Boron-based ceramics are appealing for lightweight applications in both vehicle and personnel protection, stemming from their combination of high hardness, high elastic modulus, and low density as compared to other ceramics and metal alloys. However, the performance of these ceramics and ceramic composites is lacking because of their inherent low fracture toughness and reduced strength under high-velocity threats. The objective of the present article is to briefly discuss both the challenges and the state of the art in experimental and computational approaches for engineering grain boundaries in boron-based armor ceramics, focusing mainly on boron carbide (B4C) and boron suboxide (B6O). The experimental challenges involve processing these ceramics at full density while trying to promote microstructure features such as intergranular films to improve toughness during shock. Many of the computational challenges for boron-based ceramics stem from their complex crystal structure which has hitherto complicated the exploration of grain boundaries and interfaces. However, bridging the gaps between experimental and computational studies at multiple scales to engineer grain boundaries in these boron-based ceramics may hold the key to maturing these material systems for lightweight defense applications.

  9. Engineering the ground- and excited-state absorption spectra of broadband reverse saturable absorbers

    NASA Astrophysics Data System (ADS)

    Pritchett, Timothy M.; Ferry, Michael J.; Shensky, William M.; Mott, Andrew G.; Pei, Chengkui; Sun, Wenfang

    2014-10-01

    We exploit the strong spin-orbit coupling in iridium to modify the linear absorption spectrum of a novel iridium(III) complex so as to broaden the spectral region over which it exhibits reverse saturable absorption. We discuss the design of the new chromophore, present its ground-state absorption spectrum, and report values of its singlet excited-state lifetime and singlet and triplet excited-state absorption cross sections, determined from femtosecond transient difference absorption measurements and nanosecond and picosecond open-aperture Z scans.

  10. Reverse engineering the structural and acoustic behavior of a stradivari violin

    NASA Astrophysics Data System (ADS)

    Pyrkosz, Michael

    There is a tremendous amount of mystery that surrounds the instruments of Antonio Stradivari. There have been many studies done in the past, but no one completely understands exactly how he made his instruments, or why they are still considered the best in the world. This project is designed to develop an engineering model of one of Stradivari's violins that will accurately simulate the structural and acoustic behavior of the instrument. It also hopes to shine some light on what makes the instruments of Stradivari unique when compared to other violins. It will focus on geometry and material properties, utilizing several modern engineering tools, including CT scanning, experimental modal analysis, finite element analysis, correlation techniques, and acoustic synthesis.

  11. Craniomaxillofacial reconstruction using allotransplantation and tissue engineering: challenges, opportunities, and potential synergy.

    PubMed

    Susarla, Srinivas M; Swanson, Edward; Gordon, Chad R

    2011-12-01

    The face is composed of an intricate underlying bony/cartilaginous framework that supports muscle, secretory organs, and sophisticated skin/subcutaneous structures. These components are attached through numerous ligaments and interact dynamically with a vast neurovascular network. The most sophisticated autologous reconstructive techniques, utilizing composite free-tissue flaps, are often inadequate to restore extensive maxillofacial defects. Massive craniomaxillofacial (CMF) defects resulting from trauma, oncologic resection, or congenital deformity present a unique challenge to reconstructive surgeons. Therefore, recent advances in craniofacial surgery and immunotherapy spurred the innovation of composite tissue allotransplantation (CTA), which permits reconstruction with tissue composed of all necessary components. However, CMF allotransplantation carries with it side effects of lifelong immunosuppression. Furthermore, the donor skeletal framework may not provide an ideal match, resulting in less than ideal occlusion and soft-tissue anthropometrics. An alternative to transplantation, tissue engineering, has provided hope for regenerating missing tissue and avoiding the need for immunosuppression. Many tissue subtypes, including bone and cartilage, have been successfully created, with sparse reports of clinical application. Tissue-engineered composite tissue required for complete CMF reconstruction continues to elude development, with vascular supply and tissue interactions posing the largest remaining obstacles. We report herein the current status and limitations of CTA and tissue engineering. Furthermore, we describe for the first time our vision of hybridization of CTA and engineering, utilizing the strengths of each strategy.

  12. Challenging and Future of Homogeneous Charge Compression Ignition Engines; an Advanced and Novel Concepts Review

    NASA Astrophysics Data System (ADS)

    Elkelawy, Medhat; Yu-Sheng, Zhang; Hagar, Alm El-Din; Yu, Jing-Zhou

    The potential of HCCI combustion to reduce the internal combustion engines exhaust emissions, particularly NOX and soot emissions, and to delimit the application range of this technique as well as a detailed analysis of previous and current results of combustion chemistry, emission behaviors, the challenging facing this technique, and all controlling parameters including transient states are introduced. From HCCI combustion chemistry and emissions analysis it was found that, the heavy fuels displays two-stage heat release or two stage combustion process involving low temperature oxidation (LTO) stage followed by high temperature oxidation (HTO) stage separated by a time delay between them is attributed to negative temperature coefficient (NTC), the advantage of NOX emissions reduction from HCCI engine diminishing at high load condition, HC production is reduced with increasing the engine load, and the soot ejection is negligible during all operating conditions. Valve timing, compression ratio, inlet air temperature, and EGR show an advanced control on the HCCI combustion behaviors over a wide range of speed and load. The use of EGR in HCCI operation is limited at EGR-rates about 70% at this point the reaction rates and ignition timing are so much reduced and retarded, respectively, and leads to misfiring and production of HC-emissions. Homogenization of fuel, air, and recycled burnt gases prior to ignition in addition to the control of ignition and combustion timing, and heat release rates are obstructs that must be overcome in order to realize the advantages of HCCI engine in the future.

  13. Metabolic engineering of Saccharomyces cerevisiae for production of carboxylic acids: current status and challenges.

    PubMed

    Abbott, Derek A; Zelle, Rintze M; Pronk, Jack T; van Maris, Antonius J A

    2009-12-01

    To meet the demands of future generations for chemicals and energy and to reduce the environmental footprint of the chemical industry, alternatives for petrochemistry are required. Microbial conversion of renewable feedstocks has a huge potential for cleaner, sustainable industrial production of fuels and chemicals. Microbial production of organic acids is a promising approach for production of chemical building blocks that can replace their petrochemically derived equivalents. Although Saccharomyces cerevisiae does not naturally produce organic acids in large quantities, its robustness, pH tolerance, simple nutrient requirements and long history as an industrial workhorse make it an excellent candidate biocatalyst for such processes. Genetic engineering, along with evolution and selection, has been successfully used to divert carbon from ethanol, the natural endproduct of S. cerevisiae, to pyruvate. Further engineering, which included expression of heterologous enzymes and transporters, yielded strains capable of producing lactate and malate from pyruvate. Besides these metabolic engineering strategies, this review discusses the impact of transport and energetics as well as the tolerance towards these organic acids. In addition to recent progress in engineering S. cerevisiae for organic acid production, the key limitations and challenges are discussed in the context of sustainable industrial production of organic acids from renewable feedstocks.

  14. Developing a Knowledge Base for Detection of Powertrain Failures by Reversibly Seeding Engine Faults

    DTIC Science & Technology

    2010-08-01

    engine sensors (timing, temperature and pressure) and actuators (injectors and PWM valves for controlling Boost and Injection Control pressure). The...signals with higher frequency content, we relied on a FPGA -based system that included a CAN board, a 16 bit Analog board, and a Timing board with 100 ns...plots in Fig. 5 The plots in Fig. 4 indicate that exhaust temperature in the port increases as a function of torque (more heat is generated

  15. Role of High-End Computing in Meeting NASA's Science and Engineering Challenges

    NASA Technical Reports Server (NTRS)

    Biswas, Rupak; Tu, Eugene L.; Van Dalsem, William R.

    2006-01-01

    Two years ago, NASA was on the verge of dramatically increasing its HEC capability and capacity. With the 10,240-processor supercomputer, Columbia, now in production for 18 months, HEC has an even greater impact within the Agency and extending to partner institutions. Advanced science and engineering simulations in space exploration, shuttle operations, Earth sciences, and fundamental aeronautics research are occurring on Columbia, demonstrating its ability to accelerate NASA s exploration vision. This talk describes how the integrated production environment fostered at the NASA Advanced Supercomputing (NAS) facility at Ames Research Center is accelerating scientific discovery, achieving parametric analyses of multiple scenarios, and enhancing safety for NASA missions. We focus on Columbia s impact on two key engineering and science disciplines: Aerospace, and Climate. We also discuss future mission challenges and plans for NASA s next-generation HEC environment.

  16. Biomedical engineering strategies for peripheral nerve repair: surgical applications, state of the art, and future challenges.

    PubMed

    Pfister, Bryan J; Gordon, Tessa; Loverde, Joseph R; Kochar, Arshneel S; Mackinnon, Susan E; Cullen, D Kacy

    2011-01-01

    Damage to the peripheral nervous system is surprisingly common and occurs primarily from trauma or a complication of surgery. Although recovery of nerve function occurs in many mild injuries, outcomes are often unsatisfactory following severe trauma. Nerve repair and regeneration presents unique clinical challenges and opportunities, and substantial contributions can be made through the informed application of biomedical engineering strategies. This article reviews the clinical presentations and classification of nerve injuries, in addition to the state of the art for surgical decision-making and repair strategies. This discussion presents specific challenges that must be addressed to realistically improve the treatment of nerve injuries and promote widespread recovery. In particular, nerve defects a few centimeters in length use a sensory nerve autograft as the standard technique; however, this approach is limited by the availability of donor nerve and comorbidity associated with additional surgery. Moreover, we currently have an inadequate ability to noninvasively assess the degree of nerve injury and to track axonal regeneration. As a result, wait-and-see surgical decisions can lead to undesirable and less successful "delayed" repair procedures. In this fight for time, degeneration of the distal nerve support structure and target progresses, ultimately blunting complete functional recovery. Thus, the most pressing challenges in peripheral nerve repair include the development of tissue-engineered nerve grafts that match or exceed the performance of autografts, the ability to noninvasively assess nerve damage and track axonal regeneration, and approaches to maintain the efficacy of the distal pathway and targets during the regenerative process. Biomedical engineering strategies can address these issues to substantially contribute at both the basic and applied levels, improving surgical management and functional recovery following severe peripheral nerve injury.

  17. Chosen Solutions to the Engineering Challenges of the National Spherical Torus Experiment (NSTX) Magnets

    SciTech Connect

    C. Neumeyer; H.M. Fan; J. Chrzanowski; P. Heitzenroeder; and the NSTX Team

    1999-10-01

    NSTX is one of the largest of a new class of magnetic plasma research devices known as spherical toroids (STs). The plasma in a ST is characterized by its almost spherical shape with a slender cylindrical region through its vertical axis. The so-called ''center stack'' is located in this region. It contains magnetic windings for confining the plasma, induce the plasma current, and shape the plasma. This paper will describe the engineering challenges of designing the center stack magnets to meet their operational requirements within this constrained space.

  18. Active Debris Removal - A Grand Engineering Challenge for the Twenty-First Century

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.

    2011-01-01

    The collision between Iridium 33 and Cosmos 2251 in 2009 has reignited interest in using active debris removal to remediate the near-Earth orbital debris environment. A recent NASA study shows that, in order to stabilize the environment in the low Earth orbit (LEO) region for the next 200 years, active debris removal of about five large and massive (1 to more than 8 metric tons) objects per year is needed. To develop the capability to remove five of those objects per year in a cost-effective manner truly represents a grand challenge in engineering and technology development.

  19. Achieving Closure for Bioregenerative Life Support Systems: Engineering and Ecological Challenges, Research Opportunities

    NASA Astrophysics Data System (ADS)

    Dempster, William; Allen, John P.

    Closed systems are desirable for a number of purposes: space life support systems where precious life-supporting resources need to be kept inside; biospheric systems; where global ecological pro-cesses can be studied in great detail and testbeds where research topics requiring isolation from the outside (e.g. genetically modified organisms; radioisotopes) can be studied in isolation from the outside environment and where their ecological interactions and fluxes can be studied. But to achieve and maintain closure raises both engineering and ecological challenges. Engineering challenges include methods of achieving closure for structures of different materials, and devel-oping methods of allowing energy (for heating and cooling) and information transfer through the materially closed structure. Methods of calculating degree of closure include measuring degradation rates of inert trace gases introduced into the system. An allied problem is devel-oping means of locating where leaks are located so that they may be repaired and degree of closure maintained. Once closure is achieved, methods of dealing with the pressure differen-tials between inside and outside are needed: from inflatable structures which might adjust to the pressure difference to variable volume chambers attached to the life systems component. These issues are illustrated through the engineering employed at Biosphere 2, the Biosphere 2 Test Module and the Laboratory Biosphere and a discussion of methods used by other closed ecological system facility engineers. Ecological challenges include being able to handle faster cycling rates and accentuated daily and seasonal fluxes of critical life elements such as carbon dioxide, oxygen, water, macro-and mico-nutrients. The problems of achieving sustainability in closed systems for life support include how to handle atmospheric dynamics including trace gases, producing a complete human diet and recycling nutrients and maintaining soil fertility, healthy air and

  20. Challenges and Promises of Overcoming Epistemological and Methodological Partiality: Advancing Engineering Education through Acceptance of Diverse Ways of Knowing

    ERIC Educational Resources Information Center

    Douglas, Elliot P.; Koro-Ljungberg, Mirka; Borrego, Maura

    2010-01-01

    The purpose of this paper is to explore some challenges and promises when the epistemological diversity embedded in qualitative research traditions is introduced to research communities with one dominant research paradigm, such as engineering education. Literature is used from other fields and empirical data are used from engineering education,…