Evaluation of Advanced Composite Structures Technologies for Application to NASA's Vision for Space Exploration

NASA Technical Reports Server (NTRS)

Tenney, Darrel R.

2008-01-01

AS&M performed a broad assessment survey and study to establish the potential composite materials and structures applications and benefits to the Constellation Program Elements. Trade studies were performed on selected elements to determine the potential weight or performance payoff from use of composites. Weight predictions were made for liquid hydrogen and oxygen tanks, interstage cylindrical shell, lunar surface access module, ascent module liquid methane tank, and lunar surface manipulator. A key part of this study was the evaluation of 88 different composite technologies to establish their criticality to applications for the Constellation Program. The overall outcome of this study shows that composites are viable structural materials which offer from 20% to 40% weight savings for many of the structural components that make up the Major Elements of the Constellation Program. NASA investment in advancing composite technologies for space structural applications is an investment in America's Space Exploration Program.

Crystal structure of the GTPase domain and the bundle signalling element of dynamin in the GDP state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anand, Roopsee; Eschenburg, Susanne; Reubold, Thomas F., E-mail: Reubold.Thomas@mh-hannover.de

Dynamin is the prototype of a family of large multi-domain GTPases. The 100 kDa protein is a key player in clathrin-mediated endocytosis, where it cleaves off vesicles from membranes using the energy from GTP hydrolysis. We have solved the high resolution crystal structure of a fusion protein of the GTPase domain and the bundle signalling element (BSE) of dynamin 1 liganded with GDP. The structure provides a hitherto missing snapshot of the GDP state of the hydrolytic cycle of dynamin and reveals how the switch I region moves away from the active site after GTP hydrolysis and release of inorganic phosphate.more » Comparing our structure of the GDP state with the known structures of the GTP state, the transition state and the nucleotide-free state of dynamin 1 we describe the structural changes through the hydrolytic cycle. - Highlights: • High resolution crystal structure of the GDP-state of a dynamin 1 GTPase-BSE fusion. • Visualizes one of the key states of the hydrolytic cycle of dynamin. • The dynamin-specific loop forms a helix as soon as a guanine base is present.« less

The NASA/Industry Design Analysis Methods for Vibrations (DAMVIBS) Program - A government overview. [of rotorcraft technology development using finite element method

NASA Technical Reports Server (NTRS)

Kvaternik, Raymond G.

1992-01-01

An overview is presented of government contributions to the program called Design Analysis Methods for Vibrations (DAMV) which attempted to develop finite-element-based analyses of rotorcraft vibrations. NASA initiated the program with a finite-element modeling program for the CH-47D tandem-rotor helicopter. The DAMV program emphasized four areas including: airframe finite-element modeling, difficult components studies, coupled rotor-airframe vibrations, and airframe structural optimization. Key accomplishments of the program include industrywide standards for modeling metal and composite airframes, improved industrial designs for vibrations, and the identification of critical structural contributors to airframe vibratory responses. The program also demonstrated the value of incorporating secondary modeling details to improving correlation, and the findings provide the basis for an improved finite-element-based dynamics design-analysis capability.

Shape and Stress Sensing of Multilayered Composite and Sandwich Structures Using an Inverse Finite Element Method

NASA Technical Reports Server (NTRS)

Cerracchio, Priscilla; Gherlone, Marco; Di Sciuva, Marco; Tessler, Alexander

2013-01-01

The marked increase in the use of composite and sandwich material systems in aerospace, civil, and marine structures leads to the need for integrated Structural Health Management systems. A key capability to enable such systems is the real-time reconstruction of structural deformations, stresses, and failure criteria that are inferred from in-situ, discrete-location strain measurements. This technology is commonly referred to as shape- and stress-sensing. Presented herein is a computationally efficient shape- and stress-sensing methodology that is ideally suited for applications to laminated composite and sandwich structures. The new approach employs the inverse Finite Element Method (iFEM) as a general framework and the Refined Zigzag Theory (RZT) as the underlying plate theory. A three-node inverse plate finite element is formulated. The element formulation enables robust and efficient modeling of plate structures instrumented with strain sensors that have arbitrary positions. The methodology leads to a set of linear algebraic equations that are solved efficiently for the unknown nodal displacements. These displacements are then used at the finite element level to compute full-field strains, stresses, and failure criteria that are in turn used to assess structural integrity. Numerical results for multilayered, highly heterogeneous laminates demonstrate the unique capability of this new formulation for shape- and stress-sensing.

"Structures beneath the Skin": How School Leaders Use Their Power and Authority To Create Institutional Opportunities for Developing Positive Interethnic Communities.

ERIC Educational Resources Information Center

Norte, Edmundo

1999-01-01

Explores key features of processes school leaders employ to create positive interethnic school communities, identifying five elements for effective intervention and applying an analytical model to each to provide a schema for framing elements of central importance. Addresses how school leaders use their power and authority and how they determine…

The Shock and Vibration Digest. Volume 16, Number 1

DTIC Science & Technology

1984-01-01

investigation of the measure- ment of frequency band average loss factors of structural components for use in the statistical energy analysis method of...stiffness. Matrix methods Key Words: Finite element technique. Statistical energy analysis . Experimental techniques. Framed structures, Com- puter...programs In order to further understand the practical application of the statistical energy analysis , a two section plate-like frame structure is

Parallel Three-Dimensional Computation of Fluid Dynamics and Fluid-Structure Interactions of Ram-Air Parachutes

NASA Technical Reports Server (NTRS)

Tezduyar, Tayfun E.

1998-01-01

This is a final report as far as our work at University of Minnesota is concerned. The report describes our research progress and accomplishments in development of high performance computing methods and tools for 3D finite element computation of aerodynamic characteristics and fluid-structure interactions (FSI) arising in airdrop systems, namely ram-air parachutes and round parachutes. This class of simulations involves complex geometries, flexible structural components, deforming fluid domains, and unsteady flow patterns. The key components of our simulation toolkit are a stabilized finite element flow solver, a nonlinear structural dynamics solver, an automatic mesh moving scheme, and an interface between the fluid and structural solvers; all of these have been developed within a parallel message-passing paradigm.

Static aeroelastic analysis of wings using Euler/Navier-Stokes equations coupled with improved wing-box finite element structures

NASA Technical Reports Server (NTRS)

Guruswamy, Guru P.; MacMurdy, Dale E.; Kapania, Rakesh K.

1994-01-01

Strong interactions between flow about an aircraft wing and the wing structure can result in aeroelastic phenomena which significantly impact aircraft performance. Time-accurate methods for solving the unsteady Navier-Stokes equations have matured to the point where reliable results can be obtained with reasonable computational costs for complex non-linear flows with shock waves, vortices and separations. The ability to combine such a flow solver with a general finite element structural model is key to an aeroelastic analysis in these flows. Earlier work involved time-accurate integration of modal structural models based on plate elements. A finite element model was developed to handle three-dimensional wing boxes, and incorporated into the flow solver without the need for modal analysis. Static condensation is performed on the structural model to reduce the structural degrees of freedom for the aeroelastic analysis. Direct incorporation of the finite element wing-box structural model with the flow solver requires finding adequate methods for transferring aerodynamic pressures to the structural grid and returning deflections to the aerodynamic grid. Several schemes were explored for handling the grid-to-grid transfer of information. The complex, built-up nature of the wing-box complicated this transfer. Aeroelastic calculations for a sample wing in transonic flow comparing various simple transfer schemes are presented and discussed.

Prescriptive Statements and Educational Practice: What Can Structural Equation Modeling (SEM) Offer?

ERIC Educational Resources Information Center

Martin, Andrew J.

2011-01-01

Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive statements can be made will rely on the appropriate accommodation of key elements of research design,…

Variation in printed handoff documents: Results and recommendations from a multicenter needs assessment.

PubMed

Rosenbluth, Glenn; Bale, James F; Starmer, Amy J; Spector, Nancy D; Srivastava, Rajendu; West, Daniel C; Sectish, Theodore C; Landrigan, Christopher P

2015-08-01

Handoffs of patient care are a leading root cause of medical errors. Standardized techniques exist to minimize miscommunications during verbal handoffs, but studies to guide standardization of printed handoff documents are lacking. To determine whether variability exists in the content of printed handoff documents and to identify key data elements that should be uniformly included in these documents. Pediatric hospitalist services at 9 institutions in the United States and Canada. Sample handoff documents from each institution were reviewed, and structured group interviews were conducted to understand each institution's priorities for written handoffs. An expert panel reviewed all handoff documents and structured group-interview findings, and subsequently made consensus-based recommendations for data elements that were either essential or recommended, including best overall printed handoff practices. Nine sites completed structured group interviews and submitted data. We identified substantial variation in both the structure and content of printed handoff documents. Only 4 of 23 possible data elements (17%) were uniformly present in all sites' handoff documents. The expert panel recommended the following as essential for all printed handoffs: assessment of illness severity, patient summary, action items, situation awareness and contingency plans, allergies, medications, age, weight, date of admission, and patient and hospital service identifiers. Code status and several other elements were also recommended. Wide variation exists in the content of printed handoff documents. Standardizing printed handoff documents has the potential to decrease omissions of key data during patient care transitions, which may decrease the risk of downstream medical errors. © 2015 Society of Hospital Medicine.

Structure to self-structuring: infrastructures and processes in neurobehavioural rehabilitation.

PubMed

Jackson, Howard F; Hague, Gemma; Daniels, Leanne; Aguilar, Ralph; Carr, Darren; Kenyon, William

2014-01-01

The importance of structure in post-acute brain injury rehabilitation is repeatedly mentioned in clinical practice. However, there has been little exploration of the key elements of structure that promote greater levels of functioning and emotional/behavioural stability and how these elements are optimally integrated within the infrastructure of a rehabilitation service. The nature of structure and why it is helpful is explored initially. Thereafter, the processes involved in transition from externally supported structure to the client 'self-structuring' are described. The infrastructure for facilitating these transitional processes are considered in terms of the design of services for systemic neurorehabilitation encompassing environmental factors (e.g. living environments, vocational and recreational options, step-up services and social milieus), therapeutic alliances (rehabilitation professionals, family, friends), organisational structures (service delivery, rehabilitation coaching, transdisciplinary teams) and rehabilitation philosophies and practice. It is concluded that the process of supporting individuals to transition from the 'structure' of the environment and other people towards self-structuring skills is a critical process in rehabilitation. This is reliant upon a comprehensive and robust organisational infrastructure that can successfully and flexibly integrate the core elements of structure across a transitional pathway towards increased independence and self-structuring.

Advanced manufacturing development of a composite empennage component for L-1011 aircraft. Phase 3: Production readiness verification testing

NASA Technical Reports Server (NTRS)

Jackson, A.; Sandifer, J.; Sandorff, P.; Vancleave, R.

1984-01-01

Twenty-two specimens of each of two key structural elements of the Advance Composite Vertical Fin (ACVF) were fabricated and tested. One element represented the front spar at the fuselage attachment area and the other element represented the cover at the fuselage joint area. Ten specimens of each element were selected for static testing. The coefficient of variation resulting from the tests was 3.28 percent for the ten cover specimens and 6.11 percent for the ten spar specimens, which compare well with metallic structures. The remaining twelve cover and twelve spar specimens were durability tested in environmental chambers which permitted the temperature and humidity environment to be cycled as well as the applied loads. Results of the durability tests indicated that such components will survive the service environment.

Structural safety evaluation of Gerber Arch Dam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrie, R.E.

1995-12-31

Gerber Dam, a variable radius arch structure, has experienced seepage and extensive freeze-thaw damage since its construction. A construction key was found cracked at its crest. A finite element investigation was made to evaluate the safety of the arch structure. Design methods and assumptions are evaluated. Historical performance is used in the evaluation. Stress levels, patterns, and distributions were evaluated for loads the structure has experienced to determine behavior contributing to seepage and cracking.

Analysing and Manipulating the Nanostructure of Geopolymers

NASA Astrophysics Data System (ADS)

Provis, J. L.; Hajimohammadi, A.; Rees, C. A.; van Deventer, J. S. J.

Geopolymer concretes are currently being commercialised in Australia and elsewhere around the world, with a view towards enhancing the sustainability of the world’s construction industry. The fundamental geopolymer binder is an aluminosilicate gel which displays key structural features on every length scale from Ångstroms up to centimetres, meaning that multiscale analysis is key to the development of a detailed understanding of geopolymer formation and performance. Here, we present results from investigations of geopolymer nanostructure, focusing on the use of infrared spectroscopy as an analytical tool. The effects of different combinations of precursors in geopolymer formation provides critical information, in particular with regard to the rate of reaction and its impact on the final distribution of elements and structures within the geopolymer binder. Formulations are designed so that the same composition is obtained by the use of precursors which release their constituent elements at very different rates under alkaline attack during geopolymerisation, and this provides essential information regarding the role of different elements in forming strong and durable geopolymer structures. Seeding the geopolymer mixture with very low doses of oxide nanoparticles presents several unexpected effects, both in terms of reaction kinetics and also in altering the nature of the zeolitic crystallites formed within the predominantly X-ray amorphous geopolymer binder.

NiCd battery electrodes, C-150

NASA Technical Reports Server (NTRS)

Holleck, G.; Turchan, M.; Hopkins, J.

1972-01-01

Electrodes for a nongassing negative limited nickel-cadmium cell are discussed. The key element is the development of cadmium electrodes with high hydrogen overvoltage. For this, the following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver-sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures.

A Study of the Structure and Content of Principal Selection Interviews in Pennsylvania

ERIC Educational Resources Information Center

Weber, Elizabeth A.

2012-01-01

The principal plays a key role in student success. The employment interview is a critical element in the principal selection process. This study examined the interview structure and the content of the interview questions that districts used in their principal search for the 2011-2012 school year. The research-based practices for interview…

Tapered slot antenna design for vehicular GPR applications

NASA Astrophysics Data System (ADS)

Bıçak, Emrullah; Yeǧin, Korkut; Nazlı, Hakki; Daǧ, Mahmut

2014-05-01

Vehicular applications of UWB GPR demand multiple GPR sensors operating in a harsh environment. One of the key elements of in the sensor is its UWB antenna which has minimal inter-element coupling, low group delay, high directivity and less prone to environmental conditions. Tapered slot antennas (TSA's) provide good impedance match, but they need to be modified for above specifications. Parasitic slot loaded TSA with balanced feed is proposed and a multi-channel antenna array structure is formed. Structural parameters are numerically analyzed and a prototype is built. Measurements show good performance for UWB GPR applications.

Evaluating Vegetation in the National Wetland Condition Assessment

EPA Science Inventory

Vegetation is a key biotic indicator of wetland ecological condition and forms a critical element of the USEPA 2011 National Wetland Condition Assessment. Data describing plant species composition and abundance, vegetation structure, and ground surface characteristics were colle...

Construction typification as the tool for optimizing the functioning of a robotized manufacturing system

NASA Astrophysics Data System (ADS)

Gwiazda, A.; Banas, W.; Sekala, A.; Foit, K.; Hryniewicz, P.; Kost, G.

2015-11-01

Process of workcell designing is limited by different constructional requirements. They are related to technological parameters of manufactured element, to specifications of purchased elements of a workcell and to technical characteristics of a workcell scene. This shows the complexity of the design-constructional process itself. The results of such approach are individually designed workcell suitable to the specific location and specific production cycle. Changing this parameters one must rebuild the whole configuration of a workcell. Taking into consideration this it is important to elaborate the base of typical elements of a robot kinematic chain that could be used as the tool for building Virtual modelling of kinematic chains of industrial robots requires several preparatory phase. Firstly, it is important to create a database element, which will be models of industrial robot arms. These models could be described as functional primitives that represent elements between components of the kinematic pairs and structural members of industrial robots. A database with following elements is created: the base kinematic pairs, the base robot structural elements, the base of the robot work scenes. The first of these databases includes kinematic pairs being the key component of the manipulator actuator modules. Accordingly, as mentioned previously, it includes the first stage rotary pair of fifth stage. This type of kinematic pairs was chosen due to the fact that it occurs most frequently in the structures of industrial robots. Second base consists of structural robot elements therefore it allows for the conversion of schematic structures of kinematic chains in the structural elements of the arm of industrial robots. It contains, inter alia, the structural elements such as base, stiff members - simple or angular units. They allow converting recorded schematic three-dimensional elements. Last database is a database of scenes. It includes elements of both simple and complex: simple models of technological equipment, conveyors models, models of the obstacles and like that. Using these elements it could be formed various production spaces (robotized workcells), in which it is possible to virtually track the operation of an industrial robot arm modelled in the system.

Texture zeros and hierarchical masses from flavour (mis)alignment

NASA Astrophysics Data System (ADS)

Hollik, W. G.; Saldana-Salazar, U. J.

2018-03-01

We introduce an unconventional interpretation of the fermion mass matrix elements. As the full rotational freedom of the gauge-kinetic terms renders a set of infinite bases called weak bases, basis-dependent structures as mass matrices are unphysical. Matrix invariants, on the other hand, provide a set of basis-independent objects which are of more relevance. We employ one of these invariants to give a new parametrisation of the mass matrices. By virtue of it, one gains control over its implicit implications on several mass matrix structures. The key element is the trace invariant which resembles the equation of a hypersphere with a radius equal to the Frobenius norm of the mass matrix. With the concepts of alignment or misalignment we can identify texture zeros with certain alignments whereas Froggatt-Nielsen structures in the matrix elements are governed by misalignment. This method allows further insights of traditional approaches to the underlying flavour geometry.

The structure and dynamics in solution of Cu(I) pseudoazurin from Paracoccus pantotrophus.

PubMed Central

Thompson, G. S.; Leung, Y. C.; Ferguson, S. J.; Radford, S. E.; Redfield, C.

2000-01-01

The solution structure and backbone dynamics of Cu(I) pseudoazurin, a 123 amino acid electron transfer protein from Paracoccus pantotrophus, have been determined using NMR methods. The structure was calculated to high precision, with a backbone RMS deviation for secondary structure elements of 0.35+/-0.06 A, using 1,498 distance and 55 torsion angle constraints. The protein has a double-wound Greek-key fold with two alpha-helices toward its C-terminus, similar to that of its oxidized counterpart determined by X-ray crystallography. Comparison of the Cu(I) solution structure with the X-ray structure of the Cu(II) protein shows only small differences in the positions of some of the secondary structure elements. Order parameters S2, measured for amide nitrogens, indicate that the backbone of the protein is rigid on the picosecond to nanosecond timescale. PMID:10850794

Development of a traffic data input system in Arizona for the MEPDG.

DOT National Transportation Integrated Search

2013-10-01

Accurate traffic data is one of the key data elements required for the cost-effective design of all rehabilitation and reconstruction of : pavement structures. This research study addresses the collection, preparation, and use of traffic data require...

Development of thermoplastic composite aircraft structures

NASA Technical Reports Server (NTRS)

Renieri, Michael P.; Burpo, Steven J.; Roundy, Lance M.; Todd, Stephanie A.; Kim, H. J.

1992-01-01

Efforts focused on the use of thermoplastic composite materials in the development of structural details associated with an advanced fighter fuselage section with applicability to transport design. In support of these designs, mechanics developments were conducted in two areas. First, a dissipative strain energy approach to material characterization and failure prediction, developed at the Naval Research Laboratory, was evaluated as a design/analysis tool. Second, a finite element formulation for thick composites was developed and incorporated into a lug analysis method which incorporates pin bending effects. Manufacturing concepts were developed for an upper fuel cell cover. A detailed trade study produced two promising concepts: fiber placement and single-step diaphragm forming. Based on the innovative design/manufacturing concepts for the fuselage section primary structure, elements were designed, fabricated, and structurally tested. These elements focused on key issues such as thick composite lugs and low cost forming of fastenerless, stiffener/moldine concepts. Manufacturing techniques included autoclave consolidation, single diaphragm consolidation (SDCC) and roll-forming.

Ways and Means of Adapting Culture and Structure: Case Studies. Support Document 1

ERIC Educational Resources Information Center

Clayton, Berwyn; Fisher, Thea; Harris, Roger; Bateman, Andrea; Brown, Mike

2008-01-01

The resource in this support document is a set of small case studies, offering insights into how a range of organisations have gone about adapting their organisational structure and/or culture to enhance their capability. Key elements of each case are presented with a particular emphasis on: (1) the principles that have underpinned each approach…

Quick-Connect, Self-Alining Latch

NASA Technical Reports Server (NTRS)

Burns, G. C.; Williams, E. J.

1983-01-01

Sturdy latch tolerates 10 degrees of angular mismatch in joining structural elements. Hexagonal passive plate nests in active plate, guided by capture plates and alinement keys and grooves. Center hole in both active and passive plates is 1 meter in diameter. Latch has possible uses a pipe joint, connector for parts of portable structures, and fitting for marine risers on offshore drilling rigs.

Detection of Q-Matrix Misspecification Using Two Criteria for Validation of Cognitive Structures under the Least Squares Distance Model

ERIC Educational Resources Information Center

Romero, Sonia J.; Ordoñez, Xavier G.; Ponsoda, Vincente; Revuelta, Javier

2014-01-01

Cognitive Diagnostic Models (CDMs) aim to provide information about the degree to which individuals have mastered specific attributes that underlie the success of these individuals on test items. The Q-matrix is a key element in the application of CDMs, because contains links item-attributes representing the cognitive structure proposed for solve…

A Best Practice Modular Design of a Hybrid Course Delivery Structure for an Executive Education Program

ERIC Educational Resources Information Center

Klotz, Dorothy E.; Wright, Thomas A.

2017-01-01

This article highlights a best practice approach that showcases the highly successful deployment of a hybrid course delivery structure for an Operations core course in an Executive MBA Program. A key design element of the approach was the modular design of both the course itself and the learning materials. While other hybrid deployments may stress…

Challenges in mold manufacturing for high precision molded diffractive optical elements

NASA Astrophysics Data System (ADS)

Pongs, Guido; Bresseler, Bernd; Schweizer, Klaus; Bergs, Thomas

2016-09-01

Isothermal precision glass molding of imaging optics is the key technology for mass production of precise optical elements. Especially for numerous consumer applications (e.g. digital cameras, smart phones, …), high precision glass molding is applied for the manufacturing of aspherical lenses. The usage of diffractive optical elements (DOEs) can help to further reduce the number of lenses in the optical systems which will lead to a reduced weight of hand-held optical devices. But today the application of molded glass DOEs is limited due to the technological challenges in structuring the mold surfaces. Depending on the application submicrometer structures are required on the mold surface. Furthermore these structures have to be replicated very precisely to the glass lens surface. Especially the micro structuring of hard and brittle mold materials such as Tungsten Carbide is very difficult and not established. Thus a multitude of innovative approaches using diffractive optical elements cannot be realized. Aixtooling has investigated in different mold materials and different suitable machining technologies for the micro- and sub-micrometer structuring of mold surfaces. The focus of the work lays on ultra-precision grinding to generate the diffractive pattern on the mold surfaces. This paper presents the latest achievements in diffractive structuring of Tungsten Carbide mold surfaces by ultra-precision grinding.

Anatomy of the Volar Retinacular Elements of the Hand: A Unified Nomenclature.

PubMed

Godfrey, Jenna; Rayan, Ghazi M

2018-03-01

Many investigators have described the anatomy of the volar retinacular structures of the hand over the last 60 years. As a result, multiple terms have been assigned to 1 anatomical structure and 1 name designated to more than 1 structure. Our purpose is to review the detailed anatomy and key components of the volar retinacular elements of the hand, their etymology, and their most recent descriptions. The objective also is to organize these structures into systems, which can be helpful for learners to assimilate into a practical anatomical guide. Lastly, the goal is to create a common nomenclature for identifying the volar retinacular structures of the hand in order to facilitate clear communication about them across languages. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Total quality through computer integrated manufacturing in the pharmaceutical industry.

PubMed

Ufret, C M

1995-01-01

The role of Computer Integrated Manufacturing (CIM) in the pursue of total quality in pharmaceutical manufacturing is assessed. CIM key objectives, design criteria, and performance measurements, in addition to its scope and implementation in a hierarchical structure, are explored in detail. Key elements for the success of each phase in a CIM project and a brief status of current CIM implementations in the pharmaceutical industry are presented. The role of World Class Manufacturing performance standards and other key issues to achieve full CIM benefits are also addressed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madrak, R.; Wildman, D.

The key elements have been constructed for a fast chopper system capable of removing single 2.5 MeV proton bunches spaced at 325 MHz. The average chopping rate is ~ 1 MHz. The components include a pulse delaying microstrip structure for deflecting the beam, high voltage (1.2 kV) fast (ns rise time) pulsers, and an associated wideband combiner. Various designs for the deflecting structures have been studied. Measurements of the microstrip structures' coverage factors and pulse shapes are presented.

The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: McDonnell-Douglas Helicopter Company achievements

NASA Technical Reports Server (NTRS)

Toossi, Mostafa; Weisenburger, Richard; Hashemi-Kia, Mostafa

1993-01-01

This paper presents a summary of some of the work performed by McDonnell Douglas Helicopter Company under NASA Langley-sponsored rotorcraft structural dynamics program known as DAMVIBS (Design Analysis Methods for VIBrationS). A set of guidelines which is applicable to dynamic modeling, analysis, testing, and correlation of both helicopter airframes and a large variety of structural finite element models is presented. Utilization of these guidelines and the key features of their applications to vibration modeling of helicopter airframes are discussed. Correlation studies with the test data, together with the development and applications of a set of efficient finite element model checkout procedures, are demonstrated on a large helicopter airframe finite element model. Finally, the lessons learned and the benefits resulting from this program are summarized.

Structure of the Newcastle disease virus F protein in the post-fusion conformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanson, Kurt; Wen, Xiaolin; Leser, George P.

2010-11-17

The paramyxovirus F protein is a class I viral membrane fusion protein which undergoes a significant refolding transition during virus entry. Previous studies of the Newcastle disease virus, human parainfluenza virus 3 and parainfluenza virus 5 F proteins revealed differences in the pre- and post-fusion structures. The NDV Queensland (Q) F structure lacked structural elements observed in the other two structures, which are key to the refolding and fusogenic activity of F. Here we present the NDV Australia-Victoria (AV) F protein post-fusion structure and provide EM evidence for its folding to a pre-fusion form. The NDV AV F structure containsmore » heptad repeat elements missing in the previous NDV Q F structure, forming a post-fusion six-helix bundle (6HB) similar to the post-fusion hPIV3 F structure. Electrostatic and temperature factor analysis of the F structures points to regions of these proteins that may be functionally important in their membrane fusion activity.« less

QUALITY MANAGEMENT DURING SELECTION OF TECHNOLOGIES EXAMPLE SITE MARCH AIR FORCE BASE, USA

EPA Science Inventory

This paper describes the remedial approach, organizational structure and key elements facilitating effective and efficient remediation of contaminated sites at March Air Force Base (AFB), California. The U.S. implementation and quality assurance approach to site remediation for ...

Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: manufacturing corrective optical elements for high-power laser applications.

PubMed

Menapace, Joseph A; Ehrmann, Paul E; Bayramian, Andrew J; Bullington, Amber; Di Nicola, Jean-Michel G; Haefner, Constantin; Jarboe, Jeffrey; Marshall, Christopher; Schaffers, Kathleen I; Smith, Cal

2016-07-01

Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry, is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique's capabilities. This high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.

Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: Manufacturing corrective optical elements for high-power laser applications

DOE PAGES

Menapace, Joseph A.; Ehrmann, Paul E.; Bayramian, Andrew J.; ...

2016-03-15

Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry,more » is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique’s capabilities. As a result, this high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.« less

QUALITY MANAGEMENT DURING SELECTION OF TECHNOLOGIES; EXAMPLE SITE MARCH AIR FORCE BASE, USA

EPA Science Inventory

This paper describes the remedial approach, organizational structure and key elements facilitating effective and efficient remediation of contaminated sites at March Air Force Base (AFB), California. The U.S. implementation and quality assurance approach to site remediation for a...

Closer to Learning: Social Networks, Trust, and Professional Communities

ERIC Educational Resources Information Center

Liou, Yi-Hwa; Daly, Alan J.

2014-01-01

Researchers, educators, and policymakers suggest the use of professional learning communities as one important approach to the improvement of teaching and learning. However, relatively little research examines the interplay of professional interactions (structural social capital) around instructional practices and key elements of professional…

Inversion in Mathematical Thinking and Learning

ERIC Educational Resources Information Center

Greer, Brian

2012-01-01

Inversion is a fundamental relational building block both within mathematics as the study of structures and within people's physical and social experience, linked to many other key elements such as equilibrium, invariance, reversal, compensation, symmetry, and balance. Within purely formal arithmetic, the inverse relationships between addition and…

The K-turn motif in riboswitches and other RNA species☆

PubMed Central

Lilley, David M.J.

2014-01-01

The kink turn is a widespread structure motif that introduces a tight bend into the axis of duplex RNA. This generally functions to mediate tertiary interactions, and to serve as a specific protein binding site. K-turns or closely related structures are found in at least seven different riboswitch structures, where they function as key architectural elements that help generate the ligand binding pocket. This article is part of a Special Issue entitled: Riboswitches. PMID:24798078

Optimizing a spectral element for modeling PZT-induced Lamb wave propagation in thin plates

NASA Astrophysics Data System (ADS)

Ha, Sungwon; Chang, Fu-Kuo

2010-01-01

Use of surface-mounted piezoelectric actuators to generate acoustic ultrasound has been demonstrated to be a key component of built-in nondestructive detection evaluation (NDE) techniques, which can automatically inspect and interrogate damage in hard-to-access areas in real time without disassembly of the structural parts. However, piezoelectric actuators create complex waves, which propagate through the structure. Having the capability to model piezoelectric actuator-induced wave propagation and understanding its physics are essential to developing advanced algorithms for the built-in NDE techniques. Therefore, the objective of this investigation was to develop an efficient hybrid spectral element for modeling piezoelectric actuator-induced high-frequency wave propagation in thin plates. With the hybrid element we take advantage of both a high-order spectral element in the in-plane direction and a linear finite element in the thickness direction in order to efficiently analyze Lamb wave propagation in thin plates. The hybrid spectral element out-performs other elements in terms of leading to significantly faster computation and smaller memory requirements. Use of the hybrid spectral element is proven to be an efficient technique for modeling PZT-induced (PZT: lead zirconate titanate) wave propagation in thin plates. The element enables fundamental understanding of PZT-induced wave propagation.

Predictive polymer modeling reveals coupled fluctuations in chromosome conformation and transcription

PubMed Central

Giorgetti, Luca; Galupa, Rafael; Nora, Elphège P.; Piolot, Tristan; Lam, France; Dekker, Job; Tiana, Guido; Heard, Edith

2015-01-01

Summary A new level of chromosome organization, Topologically Associating Domains (TADs), was recently uncovered by chromosome-confirmation-capture (3C) techniques. To explore TAD structure and function, we developed a polymer model that can extract the full repertoire of chromatin conformations within TADs from population-based 3C data. This model predicts actual physical distances and to what extent chromosomal contacts vary between cells. It also identifies interactions within single TADs that stabilize boundaries between TADs and allows us to identify and genetically validate key structural elements within TADs. Combining the model’s predictions with high-resolution DNA FISH and quantitative RNA FISH for TADs within the X-inactivation center (Xic), we dissect the relationship between transcription and spatial proximity to cis-regulatory elements. We demonstrate that contacts between potential regulatory elements occur in the context of fluctuating structures rather than stable loops and propose that such fluctuations may contribute to asymmetric expression in the Xic during X inactivation. PMID:24813616

Directed evolution of the periodic table: probing the electronic structure of late actinides.

PubMed

Marsh, M L; Albrecht-Schmitt, T E

2017-07-25

Recent investigations of the coordination chemistry and physical properties of berkelium (Z = 97) and californium (Z = 98) have revealed fundamental differences between post-curium elements and lighter members of the actinide series. This review highlights these developments and chronicles key findings and concepts from the last half-century that have helped usher in a new understanding of the evolution of electronic structure in the periodic table.

Premature terminator analysis sheds light on a hidden world of bacterial transcriptional attenuation.

PubMed

Naville, Magali; Gautheret, Daniel

2010-01-01

Bacterial transcription attenuation occurs through a variety of cis-regulatory elements that control gene expression in response to a wide range of signals. The signal-sensing structures in attenuators are so diverse and rapidly evolving that only a small fraction have been properly annotated and characterized to date. Here we apply a broad-spectrum detection tool in order to achieve a more complete view of the transcriptional attenuation complement of key bacterial species. Our protocol seeks gene families with an unusual frequency of 5' terminators found across multiple species. Many of the detected attenuators are part of annotated elements, such as riboswitches or T-boxes, which often operate through transcriptional attenuation. However, a significant fraction of candidates were not previously characterized in spite of their unmistakable footprint. We further characterized some of these new elements using sequence and secondary structure analysis. We also present elements that may control the expression of several non-homologous genes, suggesting co-transcription and response to common signals. An important class of such elements, which we called mobile attenuators, is provided by 3' terminators of insertion sequences or prophages that may be exapted as 5' regulators when inserted directly upstream of a cellular gene. We show here that attenuators involve a complex landscape of signal-detection structures spanning the entire bacterial domain. We discuss possible scenarios through which these diverse 5' regulatory structures may arise or evolve.

Nanobiotechnology with S-layer proteins as building blocks.

PubMed

Sleytr, Uwe B; Schuster, Bernhard; Egelseer, Eva M; Pum, Dietmar; Horejs, Christine M; Tscheliessnig, Rupert; Ilk, Nicola

2011-01-01

One of the key challenges in nanobiotechnology is the utilization of self- assembly systems, wherein molecules spontaneously associate into reproducible aggregates and supramolecular structures. In this contribution, we describe the basic principles of crystalline bacterial surface layers (S-layers) and their use as patterning elements. The broad application potential of S-layers in nanobiotechnology is based on the specific intrinsic features of the monomolecular arrays composed of identical protein or glycoprotein subunits. Most important, physicochemical properties and functional groups on the protein lattice are arranged in well-defined positions and orientations. Many applications of S-layers depend on the capability of isolated subunits to recrystallize into monomolecular arrays in suspension or on suitable surfaces (e.g., polymers, metals, silicon wafers) or interfaces (e.g., lipid films, liposomes, emulsomes). S-layers also represent a unique structural basis and patterning element for generating more complex supramolecular structures involving all major classes of biological molecules (e.g., proteins, lipids, glycans, nucleic acids, or combinations of these). Thus, S-layers fulfill key requirements as building blocks for the production of new supramolecular materials and nanoscale devices as required in molecular nanotechnology, nanobiotechnology, biomimetics, and synthetic biology. Copyright © 2011 Elsevier Inc. All rights reserved.

AIR VEHICLES INTEGRATION AND TECHNOLOGY RESEARCH (AVIATR) Task Order 0015: Predictive Capability for Hypersonic Structural Response and Life Prediction Phase 1 - Identification of Knowledge Gaps

DTIC Science & Technology

2010-08-01

using load - bearing tanks with parasitic TPS was considered to be a lower weight design when all details were accounted for. The cold structure...share one very key element with the design of load bearing hot structure – the design drive toward thin gauge metallic skin under complex and coupled...39 skin panel joints and their susceptibility to high acoustic loading coupled with transient heating, and hot structure skin deflections and

Metal Transport across Biomembranes: Emerging Models for a Distinct Chemistry*

PubMed Central

Argüello, José M.; Raimunda, Daniel; González-Guerrero, Manuel

2012-01-01

Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and alkali earth ions. Emerging structural information and functional studies have revealed distinctive features of metal transport. Among these are the relevance of multifaceted events involving metal transfer among participating proteins, the importance of coordination geometry at transmembrane transport sites, and the presence of the largely irreversible steps associated with vectorial transport. Here, we discuss how these characteristics shape novel transition metal ion transport models. PMID:22389499

Metal transport across biomembranes: emerging models for a distinct chemistry.

PubMed

Argüello, José M; Raimunda, Daniel; González-Guerrero, Manuel

2012-04-20

Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and alkali earth ions. Emerging structural information and functional studies have revealed distinctive features of metal transport. Among these are the relevance of multifaceted events involving metal transfer among participating proteins, the importance of coordination geometry at transmembrane transport sites, and the presence of the largely irreversible steps associated with vectorial transport. Here, we discuss how these characteristics shape novel transition metal ion transport models.

On the role of the SMA in the discrete sequence production task: a TMS study. Transcranial Magnetic Stimulation.

PubMed

Verwey, Willem B; Lammens, Robin; van Honk, Jack

2002-01-01

Participants practiced two discrete six-key sequences for a total of 420 trials. The 1 x 6 sequence had a unique order of key presses while the 2 x 3 sequence involved repetition of a three-key segment. Both sequences showed a long interkey interval halfway the sequence indicating hierarchical sequence control in that not only the 2 x 3 but also the 1 x 6 sequence was executed as two successive motor chunks. Besides, the second part of both sequences was executed faster than the first part. This supports the earlier notion of a motor processor executing the elements of familiar motor chunks and a cognitive processor triggering either these motor chunks or individual sequence elements. Low-frequency, off-line transcranial magnetic stimulation (TMS) of the supplementary motor area (SMA) counteracted normal improvement with practice of key presses at all sequence positions. Together, these results are in line with the notion that with moderate practice, the SMA executes short sequence fragments that are concatenated by other brain structures.

Key Elements of the Chemistry of Cytochrome P-450: The Oxygen Rebound Mechanism.

ERIC Educational Resources Information Center

Groves, John T.

1985-01-01

Discusses the structure and function of the liver protein cytochrome P-450, an important catalyst for a variety of detoxification reactions. Diagnostic substracts for this heme-containing monooxygenase, synthetic modes of the active site, and oxidations with synthetic metalloporphyrins are the major topic areas considered. (JN)

Predicting the distribution of a novel bark beetle and its pine hosts under future climate conditions

Treesearch

Steven E. Smith; Ma.G. Mendoza; Gerardo Zuniga; Kandres Kalbrook; J.L. Hayes; D.N. Byrne

2013-01-01

Understanding the distribution of key biotic elements of forest ecosystems is essential in contemporary forest management and in planning to meet future management needs. Habitat distribution (niche) models based on known occurrences provide geographical structure for such management as the environmental factors change....

A Comprehensive View of School Restructuring.

ERIC Educational Resources Information Center

Jenkins, Kenneth D.; Houlihan, G. Thomas

1991-01-01

The five key elements comprising any school organization may be described as structural, professional, renewal-oriented, curricular, and collaborative. School leaders committed to change must recognize three realities: (1) change is hard, even painful work; (2) the parts cannot be treated without treating the whole; and (3) reform starts at the…

Dynamic Social Impact: The Creation of Culture by Communication.

ERIC Educational Resources Information Center

Latane, Bibb

1996-01-01

Presents a theory of how individuals located in social space influence each other to create higher order patterns of cultural structure. Presents the theory as five propositions and six derivations, arguing that Dynamic Social Impact Theory accounts for four key features of culture: regional clustering, correlations among cultural elements,…

Probabilistic Structural Analysis Methods (PSAM) for select space propulsion system structural components

NASA Technical Reports Server (NTRS)

Cruse, T. A.

1987-01-01

The objective is the development of several modular structural analysis packages capable of predicting the probabilistic response distribution for key structural variables such as maximum stress, natural frequencies, transient response, etc. The structural analysis packages are to include stochastic modeling of loads, material properties, geometry (tolerances), and boundary conditions. The solution is to be in terms of the cumulative probability of exceedance distribution (CDF) and confidence bounds. Two methods of probability modeling are to be included as well as three types of structural models - probabilistic finite-element method (PFEM); probabilistic approximate analysis methods (PAAM); and probabilistic boundary element methods (PBEM). The purpose in doing probabilistic structural analysis is to provide the designer with a more realistic ability to assess the importance of uncertainty in the response of a high performance structure. Probabilistic Structural Analysis Method (PSAM) tools will estimate structural safety and reliability, while providing the engineer with information on the confidence that should be given to the predicted behavior. Perhaps most critically, the PSAM results will directly provide information on the sensitivity of the design response to those variables which are seen to be uncertain.

Probabilistic Structural Analysis Methods for select space propulsion system structural components (PSAM)

NASA Technical Reports Server (NTRS)

Cruse, T. A.; Burnside, O. H.; Wu, Y.-T.; Polch, E. Z.; Dias, J. B.

1988-01-01

The objective is the development of several modular structural analysis packages capable of predicting the probabilistic response distribution for key structural variables such as maximum stress, natural frequencies, transient response, etc. The structural analysis packages are to include stochastic modeling of loads, material properties, geometry (tolerances), and boundary conditions. The solution is to be in terms of the cumulative probability of exceedance distribution (CDF) and confidence bounds. Two methods of probability modeling are to be included as well as three types of structural models - probabilistic finite-element method (PFEM); probabilistic approximate analysis methods (PAAM); and probabilistic boundary element methods (PBEM). The purpose in doing probabilistic structural analysis is to provide the designer with a more realistic ability to assess the importance of uncertainty in the response of a high performance structure. Probabilistic Structural Analysis Method (PSAM) tools will estimate structural safety and reliability, while providing the engineer with information on the confidence that should be given to the predicted behavior. Perhaps most critically, the PSAM results will directly provide information on the sensitivity of the design response to those variables which are seen to be uncertain.

Key elements of optimal treatment decision-making for surgeons and older patients with colorectal or pancreatic cancer: A qualitative study.

PubMed

Geessink, Noralie H; Schoon, Yvonne; van Herk, Hanneke C P; van Goor, Harry; Olde Rikkert, Marcel G M

2017-03-01

To identify key elements of optimal treatment decision-making for surgeons and older patients with colorectal (CRC) or pancreatic cancer (PC). Six focus groups with different participants were performed: three with older CRC/PC patients and relatives, and three with physicians. Supplementary in-depth interviews were conducted in another seven patients. Framework analysis was used to identify key elements in decision-making. 23 physicians, 22 patients and 14 relatives participated. Three interacting components were revealed: preconditions, content and facilitators of decision-making. To provide optimal information about treatments' impact on an older patient's daily life, physicians should obtain an overall picture and take into account patients' frailty. Depending on patients' preferences and capacities, dividing decision-making into more sessions will be helpful and simultaneously emphasize patients' own responsibility. GPs may have a valuable contribution because of their background knowledge and supportive role. Stakeholders identified several crucial elements in the complex surgical decision-making of older CRC/PC patients. Structured qualitative research may also be of great help in optimizing other treatment directed decision-making processes. Surgeons should be trained in examining preconditions and useful facilitators in decision-making in older CRC/PC patients to optimize its content and to improve the quality of shared care. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Exploratory analysis of textual data from the Mother and Child Handbook using the text-mining method: Relationships with maternal traits and post-partum depression.

PubMed

Matsuda, Yoshio; Manaka, Tomoko; Kobayashi, Makiko; Sato, Shuhei; Ohwada, Michitaka

2016-06-01

The aim of the present study was to examine the possibility of screening apprehensive pregnant women and mothers at risk for post-partum depression from an analysis of the textual data in the Mother and Child Handbook by using the text-mining method. Uncomplicated pregnant women (n = 58) were divided into two groups according to State-Trait Anxiety Inventory grade (high trait [group I, n = 21] and low trait [group II, n = 37]) or Edinburgh Postnatal Depression Scale score (high score [group III, n = 15] and low score [group IV, n = 43]). An exploratory analysis of the textual data from the Maternal and Child Handbook was conducted using the text-mining method with the Word Miner software program. A comparison of the 'structure elements' was made between the two groups. The number of structure elements extracted by separated words from text data was 20 004 and the number of structure elements with a threshold of 2 or more as an initial value was 1168. Fifteen key words related to maternal anxiety, and six key words related to post-partum depression were extracted. The text-mining method is useful for the exploratory analysis of textual data obtained from pregnant woman, and this screening method has been suggested to be useful for apprehensive pregnant women and mothers at risk for post-partum depression. © 2016 Japan Society of Obstetrics and Gynecology.

Structural Verification of the First Orbital Wonder of the World - The Structural Testing and Analysis of the International Space Station (ISS)

NASA Technical Reports Server (NTRS)

Zipay, John J.; Bernstein, Karen S.; Bruno, Erica E.; Deloo, Phillipe; Patin, Raymond

2012-01-01

The International Space Station (ISS) can be considered one of the structural engineering wonders of the world. On par with the World Trade Center, the Colossus of Rhodes, the Statue of Liberty, the Great Pyramids, the Petronas towers and the Burj Khalifa skyscraper of Dubai, the ambition and scope of the ISS structural design, verification and assembly effort is a truly global success story. With its on-orbit life projected to be from its beginning in 1998 to the year 2020 (and perhaps beyond), all of those who participated in its development can consider themselves part of an historic engineering achievement representing all of humanity. The structural design and verification of the ISS could be the subject of many scholarly papers. Several papers have been written on the structural dynamic characterization of the ISS once it was assembled on-orbit [1], but the ground-based activities required to assure structural integrity and structural life of the individual elements from delivery to orbit through assembly and planned on-orbit operations have never been totally summarized. This paper is intended to give the reader an overview of some of the key decisions made during the structural verification planning for the elements of the U.S. On-Orbit Segment (USOS) as well as to summarize the many structural tests and structural analyses that were performed on its major elements. An effort is made for this paper to be summarily comprehensive, but as with all knowledge capture efforts of this kind, there are bound to be errors of omission. Should the reader discover any of these, please feel free to contact the principal author. The ISS (Figure 1) is composed of pre-integrated truss segments and pressurized elements supplied by NASA, the Russian Federal Space Agency (RSA), the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA). Each of these elements was delivered to orbit by a launch vehicle and connected to one another either robotically or autonomously. The primary structure of each element was assembled and verified by teams of responsible structural engineers within and among their respective agencies and agency contractors.

Evolution of a protein folding nucleus.

PubMed

Xia, Xue; Longo, Liam M; Sutherland, Mason A; Blaber, Michael

2016-07-01

The folding nucleus (FN) is a cryptic element within protein primary structure that enables an efficient folding pathway and is the postulated heritable element in the evolution of protein architecture; however, almost nothing is known regarding how the FN structurally changes as complex protein architecture evolves from simpler peptide motifs. We report characterization of the FN of a designed purely symmetric β-trefoil protein by ϕ-value analysis. We compare the structure and folding properties of key foldable intermediates along the evolutionary trajectory of the β-trefoil. The results show structural acquisition of the FN during gene fusion events, incorporating novel turn structure created by gene fusion. Furthermore, the FN is adjusted by circular permutation in response to destabilizing functional mutation. FN plasticity by way of circular permutation is made possible by the intrinsic C3 cyclic symmetry of the β-trefoil architecture, identifying a possible selective advantage that helps explain the prevalence of cyclic structural symmetry in the proteome. © 2015 The Protein Society.

Spatially oriented plasmonic ‘nanograter’ structures

PubMed Central

Liu, Zhe; Cui, Ajuan; Gong, Zhijie; Li, Hongqiang; Xia, Xiaoxiang; Shen, Tiehan H.; Li, Junjie; Yang, Haifang; Li, Wuxia; Gu, Changzhi

2016-01-01

One of the key motivations in producing 3D structures has always been the realization of metamaterials with effective constituent properties that can be tuned in all propagation directions at various frequencies. Here, we report the investigation of spatially oriented “Nanograter” structures with orientation-dependent responses over a wide spectrum by focused-ion-beam based patterning and folding of thin film nanostructures. Au nano units of different shapes, standing along specifically designated orientations, were fabricated. Experimental measurements and simulation results show that such structures offer an additional degree of freedom for adjusting optical properties with the angle of inclination, in additional to the size of the structures. The response frequency can be varied in a wide range (8 μm–14 μm) by the spatial orientation (0°–180°) of the structures, transforming the response from magnetic into electric coupling. This may open up prospects for the fabrication of 3D nanostructures as optical interconnects, focusing elements and logic elements, moving toward the realization of 3D optical circuits. PMID:27357610

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements

PubMed Central

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-01-01

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source–microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications. PMID:27527177

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements.

PubMed

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-08-04

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source-microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications.

Evolutionary impact of transposable elements on genomic diversity and lineage-specific innovation in vertebrates.

PubMed

Warren, Ian A; Naville, Magali; Chalopin, Domitille; Levin, Perrine; Berger, Chloé Suzanne; Galiana, Delphine; Volff, Jean-Nicolas

2015-09-01

Since their discovery, a growing body of evidence has emerged demonstrating that transposable elements are important drivers of species diversity. These mobile elements exhibit a great variety in structure, size and mechanisms of transposition, making them important putative actors in organism evolution. The vertebrates represent a highly diverse and successful lineage that has adapted to a wide range of different environments. These animals also possess a rich repertoire of transposable elements, with highly diverse content between lineages and even between species. Here, we review how transposable elements are driving genomic diversity and lineage-specific innovation within vertebrates. We discuss the large differences in TE content between different vertebrate groups and then go on to look at how they affect organisms at a variety of levels: from the structure of chromosomes to their involvement in the regulation of gene expression, as well as in the formation and evolution of non-coding RNAs and protein-coding genes. In the process of doing this, we highlight how transposable elements have been involved in the evolution of some of the key innovations observed within the vertebrate lineage, driving the group's diversity and success.

The interplay of early-life stress, nutrition, and immune activation programs adult hippocampal structure and function

PubMed Central

Hoeijmakers, Lianne; Lucassen, Paul J.; Korosi, Aniko

2015-01-01

Early-life adversity increases the vulnerability to develop psychopathologies and cognitive decline later in life. This association is supported by clinical and preclinical studies. Remarkably, experiences of stress during this sensitive period, in the form of abuse or neglect but also early malnutrition or an early immune challenge elicit very similar long-term effects on brain structure and function. During early-life, both exogenous factors like nutrition and maternal care, as well as endogenous modulators, including stress hormones and mediator of immunological activity affect brain development. The interplay of these key elements and their underlying molecular mechanisms are not fully understood. We discuss here the hypothesis that exposure to early-life adversity (specifically stress, under/malnutrition and infection) leads to life-long alterations in hippocampal-related cognitive functions, at least partly via changes in hippocampal neurogenesis. We further discuss how these different key elements of the early-life environment interact and affect one another and suggest that it is a synergistic action of these elements that shapes cognition throughout life. Finally, we consider different intervention studies aiming to prevent these early-life adversity induced consequences. The emerging evidence for the intriguing interplay of stress, nutrition, and immune activity in the early-life programming calls for a more in depth understanding of the interaction of these elements and the underlying mechanisms. This knowledge will help to develop intervention strategies that will converge on a more complete set of changes induced by early-life adversity. PMID:25620909

IMAT graphics manual

NASA Technical Reports Server (NTRS)

Stockwell, Alan E.; Cooper, Paul A.

1991-01-01

The Integrated Multidisciplinary Analysis Tool (IMAT) consists of a menu driven executive system coupled with a relational database which links commercial structures, structural dynamics and control codes. The IMAT graphics system, a key element of the software, provides a common interface for storing, retrieving, and displaying graphical information. The IMAT Graphics Manual shows users of commercial analysis codes (MATRIXx, MSC/NASTRAN and I-DEAS) how to use the IMAT graphics system to obtain high quality graphical output using familiar plotting procedures. The manual explains the key features of the IMAT graphics system, illustrates their use with simple step-by-step examples, and provides a reference for users who wish to take advantage of the flexibility of the software to customize their own applications.

Repetitive elements dynamics in cell identity programming, maintenance and disease.

PubMed

Bodega, Beatrice; Orlando, Valerio

2014-12-01

The days of 'junk DNA' seem to be over. The rapid progress of genomics technologies has been unveiling unexpected mechanisms by which repetitive DNA and in particular transposable elements (TEs) have evolved, becoming key issues in understanding genome structure and function. Indeed, rather than 'parasites', recent findings strongly suggest that TEs may have a positive function by contributing to tissue specific transcriptional programs, in particular as enhancer-like elements and/or modules for regulation of higher order chromatin structure. Further, it appears that during development and aging genomes experience several waves of TEs activation, and this contributes to individual genome shaping during lifetime. Interestingly, TEs activity is major target of epigenomic regulation. These findings are shedding new light on the genome-phenotype relationship and set the premises to help to explain complex disease manifestation, as consequence of TEs activity deregulation. Copyright © 2014. Published by Elsevier Ltd.

Giant magnetoresistance in perpendicularly magnetized synthetic antiferromagnetic coupling with Ir spacer

NASA Astrophysics Data System (ADS)

Fukushima, A.; Taniguchi, T.; Sugihara, A.; Yakushiji, K.; Kubota, H.; Yuasa, S.

2018-05-01

Perpendicularly magnetized magnetic tunnel junction (p-MTJ) is a key element for developing high-density spin-transfer torque switching magnetoresistive random access memory. Recently, a large exchange coupling (IEC) in the synthetic antiferromagnetic reference layer with Ir interlayer was observed in p-MTJs. The evaluation of the IEC is, however, difficult due to the electrostatic breakdown of MTJs. This study demonstrates the evaluation of the IEC with Ir interlayer in giant magnetoresistive (GMR) nanopillar. We fabricated three kinds of perpendicularly magnetized GMR elements; bottom-free structures with Cu or Ir spacer, and top-free structure with Ir spacer. The magnetoresistance (RH) loops of all samples show sharp changes of the magnetoresistance at the magnetic fields over ±10 kOe, indicating the existence of the large IECs. In particular, a sharp change of the magnetoresistance at the field over ±20 kOe was found for the element with Cu of 2 nm thickness.

Partitioning strategy for efficient nonlinear finite element dynamic analysis on multiprocessor computers

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Peters, Jeanne M.

1989-01-01

A computational procedure is presented for the nonlinear dynamic analysis of unsymmetric structures on vector multiprocessor systems. The procedure is based on a novel hierarchical partitioning strategy in which the response of the unsymmetric and antisymmetric response vectors (modes), each obtained by using only a fraction of the degrees of freedom of the original finite element model. The three key elements of the procedure which result in high degree of concurrency throughout the solution process are: (1) mixed (or primitive variable) formulation with independent shape functions for the different fields; (2) operator splitting or restructuring of the discrete equations at each time step to delineate the symmetric and antisymmetric vectors constituting the response; and (3) two level iterative process for generating the response of the structure. An assessment is made of the effectiveness of the procedure on the CRAY X-MP/4 computers.

Ditch network sustains functional connectivity and influences patterns of gene flow in an intensive agricultural landscape

PubMed Central

Favre-Bac, L; Mony, C; Ernoult, A; Burel, F; Arnaud, J-F

2016-01-01

In intensive agricultural landscapes, plant species previously relying on semi-natural habitats may persist as metapopulations within landscape linear elements. Maintenance of populations' connectivity through pollen and seed dispersal is a key factor in species persistence in the face of substantial habitat loss. The goals of this study were to investigate the potential corridor role of ditches and to identify the landscape components that significantly impact patterns of gene flow among remnant populations. Using microsatellite loci, we explored the spatial genetic structure of two hydrochorous wetland plants exhibiting contrasting local abundance and different habitat requirements: the rare and regionally protected Oenanthe aquatica and the more commonly distributed Lycopus europaeus, in an 83 km2 agricultural lowland located in northern France. Both species exhibited a significant spatial genetic structure, along with substantial levels of genetic differentiation, especially for L. europaeus, which also expressed high levels of inbreeding. Isolation-by-distance analysis revealed enhanced gene flow along ditches, indicating their key role in effective seed and pollen dispersal. Our data also suggested that the configuration of the ditch network and the landscape elements significantly affected population genetic structure, with (i) species-specific scale effects on the genetic neighborhood and (ii) detrimental impact of human ditch management on genetic diversity, especially for O. aquatica. Altogether, these findings highlighted the key role of ditches in the maintenance of plant biodiversity in intensive agricultural landscapes with few remnant wetland habitats. PMID:26486611

Parts function as perceptual organizational entities in infancy.

PubMed

Kangas, Ashley; Zieber, Nicole; Hayden, Angela; Bhatt, Ramesh S

2013-08-01

Both objects and parts function as organizational entities in adult perception. Prior research has indicated that objects affect organization early in life: Infants grouped elements located within object boundaries and segregated them from those located on different objects. Here, we examined whether parts also induce grouping in infancy. Five- and 6.5-month-olds were habituated to two-part objects containing element pairs. In a subsequent test, infants treated groupings of elements that crossed part boundaries as novel, in comparison with groupings that had shared a common part during habituation. In contrast, the same arrangement of elements failed to elicit evidence of grouping in control conditions in which the elements were not surrounded by closed part boundaries. Thus, infants grouped and segregated elements on the basis of part structure. Part-based processing is a key aspect of many theories of perception. The present research adds to this literature by indicating that parts function as organizational entities early in life.

The notochord: structure and functions.

PubMed

Corallo, Diana; Trapani, Valeria; Bonaldo, Paolo

2015-08-01

The notochord is an embryonic midline structure common to all members of the phylum Chordata, providing both mechanical and signaling cues to the developing embryo. In vertebrates, the notochord arises from the dorsal organizer and it is critical for proper vertebrate development. This evolutionary conserved structure located at the developing midline defines the primitive axis of embryos and represents the structural element essential for locomotion. Besides its primary structural function, the notochord is also a source of developmental signals that patterns surrounding tissues. Among the signals secreted by the notochord, Hedgehog proteins play key roles during embryogenesis. The Hedgehog signaling pathway is a central regulator of embryonic development, controlling the patterning and proliferation of a wide variety of organs. In this review, we summarize the current knowledge on notochord structure and functions, with a particular emphasis on the key developmental events that take place in vertebrates. Moreover, we discuss some genetic studies highlighting the phenotypic consequences of impaired notochord development, which enabled to understand the molecular basis of different human congenital defects and diseases.

Structural Equation Modeling of Knowledge Content Improvement Using Inquiry Based Instruction

ERIC Educational Resources Information Center

Reeves, Christopher Gonwa; Fostvedt, Luke; Laugerman, Marcia; Baenziger, Joan; Shelley, Mack; Hand, Brian; Therrien, William

2013-01-01

A key element in science education is establishing and maintaining linkages between teachers and researchers that can eventuate in enhanced student outcomes. Determining when and where a new educational program or intervention results in an enhanced outcome can be sensitive to many different forces that the researcher must carefully manage. The…

Ultra-wideband technology radio frequency interference effects to global positioning system receivers and interference encounter scenario development : second interim report

DOT National Transportation Integrated Search

2001-03-27

The Global Positioning System (GPS) is significant because it is a key element in the development of the Free Flight" air traffic management structure of the future which is needed to enable the expected growth of air travel and alleviate the current...

Business planning. Reasons, definitions, and elements.

PubMed

Cardamone, Michael A; Shaver, Mark; Werthman, Ronald

2004-04-01

The Johns Hopkins Hospital and Health System has developed a centralized business planning structure that provides for creativity while incorporating a system of checks and balances. Combining standardization with flexibility allows for customization and variability. Using a team approach, the organization allows key players to contribute their experience and expertise to the planning for each new project.

Impaired Perception of Syllable Stress in Children with Dyslexia: A Longitudinal Study

ERIC Educational Resources Information Center

Goswami, Usha; Mead, Natasha; Fosker, Tim; Huss, Martina; Barnes, Lisa; Leong, Victoria

2013-01-01

Prosodic patterning is a key structural element of spoken language. However, the potential role of prosodic awareness in the phonological difficulties that characterise children with developmental dyslexia has been little studied. Here we report the first longitudinal study of sensitivity to syllable stress in children with dyslexia, enabling the…

Promoting Connectedness through Whole-School Approaches: Key Elements and Pathways of Influence

ERIC Educational Resources Information Center

Rowe, Fiona; Stewart, Donald

2011-01-01

Purpose: A comprehensive whole-school approach has emerged as a promising model for building connectedness in the school setting. The health-promoting school model, through its whole-school orientation and attention to the school organizational environment, identifies structures and processes that influence school connectedness. This paper aims to…

Pharmacophore Hybridization To Discover Novel Topoisomerase II Poisons with Promising Antiproliferative Activity.

PubMed

Ortega, Jose Antonio; Riccardi, Laura; Minniti, Elirosa; Borgogno, Marco; Arencibia, Jose M; Greco, Maria L; Minarini, Anna; Sissi, Claudia; De Vivo, Marco

2018-02-08

We used a pharmacophore hybridization strategy to combine key structural elements of merbarone and etoposide and generated new type II topoisomerase (topoII) poisons. This first set of hybrid topoII poisons shows promising antiproliferative activity on human cancer cells, endorsing their further exploration for anticancer drug discovery.

Dynamic Creative Interaction Networks and Team Creativity Evolution: A Longitudinal Study

ERIC Educational Resources Information Center

Jiang, Hui; Zhang, Qing-Pu; Zhou, Yang

2018-01-01

To assess the dynamical effects of creative interaction networks on team creativity evolution, this paper elaborates a theoretical framework that links the key elements of creative interaction networks, including node, edge and network structure, to creativity in teams. The process of team creativity evolution is divided into four phases,…

How Will Welfare Reform Affect Childbearing and Family Structure Decisions? Discussion Paper.

ERIC Educational Resources Information Center

Peters, H. Elizabeth; Plotnick, Robert D.; Jeong, Se-Ook

This paper summarizes changes in key elements of welfare policy and in closely related policies on child support enforcement and sex education and family planning programs. Drawing on a conceptual framework that highlights how incentives created by public policy can affect demographic behaviors, the paper concludes that, as Congress intended,…

Inhibition Mechanism of an Anti-CRISPR Suppressor AcrIIA4 Targeting SpyCas9.

PubMed

Yang, Hui; Patel, Dinshaw J

2017-07-06

Prokaryotic CRISPR-Cas adaptive immune systems utilize sequence-specific RNA-guided endonucleases to defend against infection by viruses, bacteriophages, and mobile elements, while these foreign genetic elements evolve diverse anti-CRISPR proteins to overcome the CRISPR-Cas-mediated defense of the host. Recently, AcrIIA2 and AcrIIA4, encoded by Listeria monocytogene prophages, were shown to block the endonuclease activity of type II-A Streptococcus pyogene Cas9 (SpyCas9). We now report the crystal structure of AcrIIA4 in complex with single-guide RNA-bound SpyCas9, thereby establishing that AcrIIA4 preferentially targets critical residues essential for PAM duplex recognition, as well as blocks target DNA access to key catalytic residues lining the RuvC pocket. These structural insights, validated by biochemical assays on key mutants, demonstrate that AcrIIA4 competitively occupies both PAM-interacting and non-target DNA strand cleavage catalytic pockets. Our studies provide insights into anti-CRISPR-mediated suppression mechanisms for inactivating SpyCas9, thereby broadening the applicability of CRISPR-Cas regulatory tools for genome editing. Published by Elsevier Inc.

Promoting quality: the health-care organization from a management perspective.

PubMed

Glickman, Seth W; Baggett, Kelvin A; Krubert, Christopher G; Peterson, Eric D; Schulman, Kevin A

2007-12-01

Although agreement about the need for quality improvement in health care is almost universal, the means of achieving effective improvement in overall care is not well understood. Avedis Donabedian developed the structure-process-outcome framework in which to think about quality-improvement efforts. There is now a robust evidence-base in the quality-improvement literature on process and outcomes, but structure has received considerably less attention. The health-care field would benefit from expanding the current interpretation of structure to include broader perspectives on organizational attributes as primary determinants of process change and quality improvement. We highlight and discuss the following key elements of organizational attributes from a management perspective: (i) executive management, including senior leadership and board responsibilities (ii) culture, (iii) organizational design, (iv) incentive structures and (v) information management and technology. We discuss the relevant contributions from the business and medical literature for each element, and provide this framework as a roadmap for future research in an effort to develop the optimal definition of 'structure' for transforming quality-improvement initiatives.

Structure and Functional Characterization of Human Aspartate Transcarbamoylase, the Target of the Anti-tumoral Drug PALA.

PubMed

Ruiz-Ramos, Alba; Velázquez-Campoy, Adrián; Grande-García, Araceli; Moreno-Morcillo, María; Ramón-Maiques, Santiago

2016-07-06

CAD, the multienzymatic protein that initiates and controls de novo synthesis of pyrimidines in animals, associates through its aspartate transcarbamoylase (ATCase) domain into particles of 1.5 MDa. Despite numerous structures of prokaryotic ATCases, we lack structural information on the ATCase domain of CAD. Here, we report the structure and functional characterization of human ATCase, confirming the overall similarity with bacterial homologs. Unexpectedly, human ATCase exhibits cooperativity effects that reduce the affinity for the anti-tumoral drug PALA. Combining structural, mutagenic, and biochemical analysis, we identified key elements for the necessary regulation and transmission of conformational changes leading to cooperativity between subunits. Mutation of one of these elements, R2024, was recently found to cause the first non-lethal CAD deficit. We reproduced this mutation in human ATCase and measured its effect, demonstrating that this arginine is part of a molecular switch that regulates the equilibrium between low- and high-affinity states for the ligands. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of High Fidelity Methods in Multidisciplinary Optimization-A Preliminary Survey

NASA Technical Reports Server (NTRS)

Guruswamy, Guru P.; Kwak, Dochan (Technical Monitor)

2002-01-01

Multidisciplinary optimization is a key element of design process. To date multidiscipline optimization methods that use low fidelity methods are well advanced. Optimization methods based on simple linear aerodynamic equations and plate structural equations have been applied to complex aerospace configurations. However, use of high fidelity methods such as the Euler/ Navier-Stokes for fluids and 3-D (three dimensional) finite elements for structures has begun recently. As an activity of Multidiscipline Design Optimization Technical Committee (MDO TC) of AIAA (American Institute of Aeronautics and Astronautics), an effort was initiated to assess the status of the use of high fidelity methods in multidisciplinary optimization. Contributions were solicited through the members MDO TC committee. This paper provides a summary of that survey.

Low-cost Active Structural Control Space Experiment (LASC)

NASA Technical Reports Server (NTRS)

Robinett, Rush; Bukley, Angelia P.

1992-01-01

The DOE Lab Director's Conference identified the need for the DOE National Laboratories to actively and aggressively pursue ways to apply DOE technology to problems of national need. Space structures are key elements of DOD and NASA space systems and a space technology area in which DOE can have a significant impact. LASC is a joint agency space technology experiment (DOD Phillips, NASA Marshall, and DOE Sandia). The topics are presented in viewgraph form and include the following: phase 4 investigator testbed; control of large flexible structures in orbit; INFLEX; Controls, Astrophysics; and structures experiments in space; SARSAT; and LASC mission objectives.

[Scale of organizational learning in schools. Organizational learning is a key element for the development of organizations].

PubMed

López, Verónica; Ahumada, Luis; Olivares, Rodrigo; González, Alvaro

2012-05-01

Organizational learning is a key element for the development of organizations. School organizations are not exempt from this challenge and they currently face a highly dynamic and demanding context of education policies that emphasize the school's ability to learn. Thus, research on organizational learning in educational contexts requires valid instruments that are sensitive to the specifics of schools as organizations. In this study, we adapted and validated a scale of organizational learning in a sample of 119 Chilean municipal schools (N= 1,545). The results suggest a structural model made up of three factors: culture of learning, strategic clarity, and group learning. These factors predicted dimensions of educational achievement, as measured through the National Assessment System of Educational Achievement (SNED). Results are discussed in view of the literature on school improvement.

Development of an Internet-Based Parent Training Intervention for Children with ASD

DTIC Science & Technology

2014-10-01

had mean pretests scores that were significantly lower than did individuals with master’s degrees, all three groups per- formed comparably on the...focus groups with 8-10 key stakeholders to gain feedback on the structural elements of the program. Focus group members will participate in two focus... groups , three months apart. In the first focus group , 9    we will obtain feedback on the structure of the online systems training and self-directed

Global-local methodologies and their application to nonlinear analysis. [for structural postbuckling study

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.

1986-01-01

An assessment is made of the potential of different global-local analysis strategies for predicting the nonlinear and postbuckling responses of structures. Two postbuckling problems of composite panels are used as benchmarks and the application of different global-local methodologies to these benchmarks is outlined. The key elements of each of the global-local strategies are discussed and future research areas needed to realize the full potential of global-local methodologies are identified.

Structural and Functional insights into the catalytic mechanism of the Type II NADH:quinone oxidoreductase family

PubMed Central

Marreiros, Bruno C.; Sena, Filipa V.; Sousa, Filipe M.; Oliveira, A. Sofia F.; Soares, Cláudio M.; Batista, Ana P.; Pereira, Manuela M.

2017-01-01

Type II NADH:quinone oxidoreductases (NDH-2s) are membrane proteins involved in respiratory chains. These proteins contribute indirectly to the establishment of the transmembrane difference of electrochemical potential by catalyzing the reduction of quinone by oxidation of NAD(P)H. NDH-2s are widespread enzymes being present in the three domains of life. In this work, we explored the catalytic mechanism of NDH-2 by investigating the common elements of all NDH-2s, based on the rationale that conservation of such elements reflects their structural/functional importance. We observed conserved sequence motifs and structural elements among 1762 NDH-2s. We identified two proton pathways possibly involved in the protonation of the quinone. Our results led us to propose the first catalytic mechanism for NDH-2 family, in which a conserved glutamate residue, E172 (in NDH-2 from Staphylococcus aureus) plays a key role in proton transfer to the quinone pocket. This catalytic mechanism may also be extended to the other members of the two-Dinucleotide Binding Domains Flavoprotein (tDBDF) superfamily, such as sulfide:quinone oxidoreductases. PMID:28181562

Large Area X-Ray Spectroscopy Mission

NASA Technical Reports Server (NTRS)

Tananbaum, H.

1997-01-01

The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

Mesh Deformation Based on Fully Stressed Design: The Method and Two-Dimensional Examples

NASA Technical Reports Server (NTRS)

Hsu, Su-Yuen; Chang, Chau-Lyan

2007-01-01

Mesh deformation in response to redefined boundary geometry is a frequently encountered task in shape optimization and analysis of fluid-structure interaction. We propose a simple and concise method for deforming meshes defined with three-node triangular or four-node tetrahedral elements. The mesh deformation method is suitable for large boundary movement. The approach requires two consecutive linear elastic finite-element analyses of an isotropic continuum using a prescribed displacement at the mesh boundaries. The first analysis is performed with homogeneous elastic property and the second with inhomogeneous elastic property. The fully stressed design is employed with a vanishing Poisson s ratio and a proposed form of equivalent strain (modified Tresca equivalent strain) to calculate, from the strain result of the first analysis, the element-specific Young s modulus for the second analysis. The theoretical aspect of the proposed method, its convenient numerical implementation using a typical linear elastic finite-element code in conjunction with very minor extra coding for data processing, and results for examples of large deformation of two-dimensional meshes are presented in this paper. KEY WORDS: Mesh deformation, shape optimization, fluid-structure interaction, fully stressed design, finite-element analysis, linear elasticity, strain failure, equivalent strain, Tresca failure criterion

Structure of a prokaryotic sodium channel pore reveals essential gating elements and an outer ion binding site common to eukaryotic channels

PubMed Central

Shaya, David; Findeisen, Felix; Abderemane-Ali, Fayal; Arrigoni, Cristina; Wong, Stephanie; Nurva, Shailika Reddy; Loussouarn, Gildas; Minor, Daniel L.

2013-01-01

Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail ‘neck’, are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the ‘outer ion’ site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies shows that this site forms a previously unknown determinant of CaV high affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily. PMID:24120938

Dark-field X-ray microscopy for multiscale structural characterization

NASA Astrophysics Data System (ADS)

Simons, H.; King, A.; Ludwig, W.; Detlefs, C.; Pantleon, W.; Schmidt, S.; Snigireva, I.; Snigirev, A.; Poulsen, H. F.

2015-01-01

Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. Here we present dark-field X-ray microscopy; a non-destructive microscopy technique for the three-dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1 mm within embedded sampling volumes. The technique, which allows ‘zooming’ in and out in both direct and angular space, is demonstrated by an annealing study of plastically deformed aluminium. Facilitating the direct study of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements (for example, positioned at interfaces) is crucial to the performance and lifetime of macro-scale devices and components thereof.

Structural insight into TPX2-stimulated microtubule assembly

PubMed Central

2017-01-01

During mitosis and meiosis, microtubule (MT) assembly is locally upregulated by the chromatin-dependent Ran-GTP pathway. One of its key targets is the MT-associated spindle assembly factor TPX2. The molecular mechanism of how TPX2 stimulates MT assembly remains unknown because structural information about the interaction of TPX2 with MTs is lacking. Here, we determine the cryo-electron microscopy structure of a central region of TPX2 bound to the MT surface. TPX2 uses two flexibly linked elements (’ridge’ and ‘wedge’) in a novel interaction mode to simultaneously bind across longitudinal and lateral tubulin interfaces. These MT-interacting elements overlap with the binding site of importins on TPX2. Fluorescence microscopy-based in vitro reconstitution assays reveal that this interaction mode is critical for MT binding and facilitates MT nucleation. Together, our results suggest a molecular mechanism of how the Ran-GTP gradient can regulate TPX2-dependent MT formation. PMID:29120325

High-resolution three-dimensional NMR structure of the KRAS proto-oncogene promoter reveals key features of a G-quadruplex involved in transcriptional regulation.

PubMed

Kerkour, Abdelaziz; Marquevielle, Julien; Ivashchenko, Stefaniia; Yatsunyk, Liliya A; Mergny, Jean-Louis; Salgado, Gilmar F

2017-05-12

Non-canonical base pairing within guanine-rich DNA and RNA sequences can produce G-quartets, whose stacking leads to the formation of a G-quadruplex (G4). G4s can coexist with canonical duplex DNA in the human genome and have been suggested to suppress gene transcription, and much attention has therefore focused on studying G4s in promotor regions of disease-related genes. For example, the human KRAS proto-oncogene contains a nuclease-hypersensitive element located upstream of the major transcription start site. The KRAS nuclease-hypersensitive element (NHE) region contains a G-rich element (22RT; 5'-AGGGCGGTGTGGGAATAGGGAA-3') and encompasses a Myc-associated zinc finger-binding site that regulates KRAS transcription. The NEH region therefore has been proposed as a target for new drugs that control KRAS transcription, which requires detailed knowledge of the NHE structure. In this study, we report a high-resolution NMR structure of the G-rich element within the KRAS NHE. We found that the G-rich element forms a parallel structure with three G-quartets connected by a four-nucleotide loop and two short one-nucleotide double-chain reversal loops. In addition, a thymine bulge is found between G8 and G9. The loops of different lengths and the presence of a bulge between the G-quartets are structural elements that potentially can be targeted by small chemical ligands that would further stabilize the structure and interfere or block transcriptional regulators such as Myc-associated zinc finger from accessing their binding sites on the KRAS promoter. In conclusion, our work suggests a possible new route for the development of anticancer agents that could suppress KRAS expression. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The fuelbed: a key element of the Fuel Characteristic Classification System.

Treesearch

Cynthia L. Riccardi; Roger D. Ottmar; David V. Sandberg; Anne Andreu; Ella Elman; Karen Kopper; Jennifer Long

2007-01-01

Wildland fuelbed characteristics are temporally and spatially complex and can vary widely across regions. To capture this variability, we designed the Fuel Characteristic Classification System (FCCS), a national system to create fuelbeds and classify those fuelbeds for their capacity to support fire and consume fuels. This paper describes the structure of the fuelbeds...

Career Survival: Strategic Job and Role Planning. Pfeiffer Career Series.

ERIC Educational Resources Information Center

Schein, Edgar H.

This book was designed to help managers and employees to decipher the two crucial elements in work design and human resource planning: the role network that surrounds every position and the key stakeholders whose expectations define the essence of the job. It provides a structured process for analyzing one's own job as well as the jobs of…

Does the Document Matter? The Evolving Role of Syllabi in Higher Education

ERIC Educational Resources Information Center

Palmer, Michael S.; Wheeler, Lindsay B.; Aneece, Itiya

2016-01-01

Essentially, the syllabus is a physical artifact outlining key structural elements of a course. It often serves contractual, record keeping, and/or communication functions. It is the place where faculty describe what content they will cover, what books and articles their students will read, the assignments they will complete, dates when things are…

Student Perceptions of the Cell Biology Laboratory Learning Environment in Four Undergraduate Science Courses in Spain

ERIC Educational Resources Information Center

De Juan, Joaquin; Pérez-Cañaveras, Rosa M.; Segovia, Yolanda; Girela, Jose Luis; Martínez-Ruiz, Noemi; Romero-Rameta, Alejandro; Gómez-Torres, Maria José; Vizcaya-Moreno, M. Flores

2016-01-01

Cell biology is an academic discipline that organises and coordinates the learning of the structure, function and molecular composition of cells in some undergraduate biomedical programs. Besides course content and teaching methodologies, the laboratory environment is considered a key element in the teaching of and learning of cell biology. The…

Structured pathology reporting improves the macroscopic assessment of rectal tumour resection specimens.

PubMed

King, Simon; Dimech, Margaret; Johnstone, Susan

2016-06-01

We examined whether introduction of a structured macroscopic reporting template for rectal tumour resection specimens improved the completeness and efficiency in collecting key macroscopic data elements. Fifty free text (narrative) macroscopic reports retrieved from 2012 to 2014 were compared with 50 structured macroscopic reports from 2013 to 2015, all of which were generated at John Hunter Hospital, Newcastle, NSW. The six standard macroscopic data elements examined in this study were reported in all 50 anatomical pathology reports using a structured macroscopic reporting dictation template. Free text reports demonstrated significantly impaired data collection when recording intactness of mesorectum (p<0.001), relationship to anterior peritoneal reflection (p=0.028) and distance of tumour to the non-peritonealised circumferential margin (p<0.001). The number of words used was also significantly (p<0.001) reduced using pre-formatted structured reports compared to free text reports. The introduction of a structured reporting dictation template improves data collection and may reduce the subsequent administrative burden when macroscopically evaluating rectal resections. Copyright © 2016 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.

Challenges in Scale-Resolving Simulations of turbulent wake flows with coherent structures

NASA Astrophysics Data System (ADS)

Pereira, Filipe S.; Eça, Luís; Vaz, Guilherme; Girimaji, Sharath S.

2018-06-01

The objective of this work is to investigate the challenges encountered in Scale-Resolving Simulations (SRS) of turbulent wake flows driven by spatially-developing coherent structures. SRS of practical interest are expressly intended for efficiently computing such flows by resolving only the most important features of the coherent structures and modelling the remainder as stochastic field. The success of SRS methods depends upon three important factors: i) ability to identify key flow mechanisms responsible for the generation of coherent structures; ii) determine the optimum range of resolution required to adequately capture key elements of coherent structures; and iii) ensure that the modelled part is comprised nearly exclusively of fully-developed stochastic turbulence. This study considers the canonical case of the flow around a circular cylinder to address the aforementioned three key issues. It is first demonstrated using experimental evidence that the vortex-shedding instability and flow-structure development involves four important stages. A series of SRS computations of progressively increasing resolution (decreasing cut-off length) are performed. An a priori basis for locating the origin of the coherent structures development is proposed and examined. The criterion is based on the fact that the coherent structures are generated by the Kelvin-Helmholtz (KH) instability. The most important finding is that the key aspects of coherent structures can be resolved only if the effective computational Reynolds number (based on total viscosity) exceeds the critical value of the KH instability in laminar flows. Finally, a quantitative criterion assessing the nature of the unresolved field based on the strain-rate ratio of mean and unresolved fields is examined. The two proposed conditions and rationale offer a quantitative basis for developing "good practice" guidelines for SRS of complex turbulent wake flows with coherent structures.

The Possible Effects of Potential Key Technological Developments on the Force Structure of the Australian Army in 2040

DTIC Science & Technology

2014-12-01

time as detection abilities improve. • There is a danger of a loss of human skills in collection that becomes evident when the network connection...perceptions.”[3]. The WS elements in this area are weighted to human populations due to the nature of the operations conducted in this area and the...structures. Before too much weight is placed on the tentative conclusions that are presented in this section it would be necessary to talk with

B38: an all-boron fullerene analogue

NASA Astrophysics Data System (ADS)

Lv, Jian; Wang, Yanchao; Zhu, Li; Ma, Yanming

2014-09-01

Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue.Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01846j

FILTSoft: A computational tool for microstrip planar filter design

NASA Astrophysics Data System (ADS)

Elsayed, M. H.; Abidin, Z. Z.; Dahlan, S. H.; Cholan N., A.; Ngu, Xavier T. I.; Majid, H. A.

2017-09-01

Filters are key component of any communication system to control spectrum and suppress interferences. Designing a filter involves long process as well as good understanding of the basic hardware technology. Hence this paper introduces an automated design tool based on Matlab-GUI, called the FILTSoft (acronym for Filter Design Software) to ease the process. FILTSoft is a user friendly filter design tool to aid, guide and expedite calculations from lumped elements level to microstrip structure. Users just have to provide the required filter specifications as well as the material description. FILTSoft will calculate and display the lumped element details, the planar filter structure, and the expected filter's response. An example of a lowpass filter design was calculated using FILTSoft and the results were validated through prototype measurement for comparison purposes.

Key Elements of a Good Mathematics Lesson as Seen by Japanese Junior High School Teachers

ERIC Educational Resources Information Center

Ebaeguin, Marlon; Stephens, Max

2016-01-01

This study makes a comparison between what literature on Japanese Lesson Study suggests are key elements of a good mathematics lesson and what junior high school mathematics teachers in Japan value in planning their lessons. The teachers' strong consensus in their endorsements of these key elements explains why Japanese teachers strongly support…

Development of a preprototype times wastewater recovery subsystem

NASA Technical Reports Server (NTRS)

Roebelen, G. J., Jr.; Dehner, G. F.

1982-01-01

A three-man wastewater recovery preprototype subsystem using a hollow fiber membrane evaporator with a thermoelectric heat pump to provide efficient potable water recovery from wastewater on extended duration space flights was designed, fabricated, and tested at one-gravity. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem. The tubular hollow fiber elements provide positive liquid/gas phase control with no moving parts, and provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery. Application and integration of these key elements solved problems inherent in all previous reclamation subsystem designs.

Organizational and training factors that promote team science: A qualitative analysis and application of theory to the National Institutes of Health's BIRCWH career development program.

PubMed

Guise, Jeanne-Marie; Winter, Susan; Fiore, Stephen M; Regensteiner, Judith G; Nagel, Joan

2017-04-01

Research organizations face challenges in creating infrastructures that cultivates and sustains interdisciplinary team science. The objective of this paper is to identify structural elements of organizations and training that promote team science. We qualitatively analyzed the National Institutes of Health's Building Interdisciplinary Research Careers in Women's Health, K12 using organizational psychology and team science theories to identify organizational design factors for successful team science and training. Seven key design elements support team science: (1) semiformal meta-organizational structure, (2) shared context and goals, (3) formal evaluation processes, (4) meetings to promote communication, (5) role clarity in mentoring, (6) building interpersonal competencies among faculty and trainees, and (7) designing promotion and tenure and other organizational processes to support interdisciplinary team science. This application of theory to a long-standing and successful program provides important foundational elements for programs and institutions to consider in promoting team science.

Method and apparatus for staking optical elements

DOEpatents

Woods, Robert O.

1988-01-01

A method and apparatus for staking two optical elements together in order to retain their alignment is disclosed. The apparatus includes a removable adaptor made up of first and second adaptor bodies each having a lateral slot in their front and side faces. The adaptor also includes a system for releasably attaching each adaptor body to a respective optical element such that when the two optical elements are positioned relative to one another the adaptor bodies are adjacent and the lateral slots therein are aligned to form key slots. The adaptor includes keys which are adapted to fit into the key slots. A curable filler material is employed to retain the keys in the key slots and thereby join the first and second adaptor bodies to form the adaptor. Also disclosed is a method for staking together two optical elements employing the adaptor of the present invention.

Method and apparatus for staking optical elements

DOEpatents

Woods, Robert O.

1988-10-04

A method and apparatus for staking two optical elements together in order to retain their alignment is disclosed. The apparatus includes a removable adaptor made up of first and second adaptor bodies each having a lateral slot in their front and side faces. The adaptor also includes a system for releasably attaching each adaptor body to a respective optical element such that when the two optical elements are positioned relative to one another the adaptor bodies are adjacent and the lateral slots therein are aligned to form key slots. The adaptor includes keys which are adapted to fit into the key slots. A curable filler material is employed to retain the keys in the key slots and thereby join the first and second adaptor bodies to form the adaptor. Also disclosed is a method for staking together two optical elements employing the adaptor of the present invention.

Topographical optimization of structures for use in musical instruments and other applications

NASA Astrophysics Data System (ADS)

Kirkland, William Brandon

Mallet percussion instruments such as the xylophone, marimba, and vibraphone have been produced and tuned since their inception by arduously grinding the keys to achieve harmonic ratios between their 1st, 2 nd, and 3rd transverse modes. In consideration of this, it would be preferable to have defined mathematical models such that the keys of these instruments can be produced quickly and reliably. Additionally, physical modeling of these keys or beams provides a useful application of non-uniform beam vibrations as studied by Euler-Bernoulli and Timoshenko beam theories. This thesis work presents a literature review of previous studies regarding mallet percussion instrument design and optimization of non-uniform keys. The progression of previous research from strictly mathematical approaches to finite element methods is shown, ultimately arriving at the most current optimization techniques used by other authors. However, previous research varies slightly in the relative degree of accuracy to which a non-uniform beam can be modeled. Typically, accuracies are shown in literature as 1% to 2% error. While this seems attractive, musical tolerances require 0.25% error and beams are otherwise unsuitable. This research seeks to build on and add to the previous field research by optimizing beam topology and machining keys within tolerances that no further tuning is required. The optimization methods relied on finite element analysis and used harmonic modal frequencies as constraints rather than arguments of an error function to be optimized. Instead, the beam mass was minimized while the modal frequency constraints were required to be satisfied within 0.25% tolerance. The final optimized and machined keys of an A4 vibraphone were shown to be accurate within the required musical tolerances, with strong resonance at the designed frequencies. The findings solidify a systematic method for designing musical structures for accuracy and repeatability upon manufacture.

Structural aspects of denitrifying enzymes.

PubMed

Moura, I; Moura, J J

2001-04-01

The reduction of nitrate to nitrogen gas via nitrite, nitric oxide and nitrous oxide is the metabolic pathway usually known as denitrification, a key step in the nitrogen cycle. As observed for other elemental cycles, a battery of enzymes are utilized, namely the reductases for nitrate, nitrite, nitric oxide and nitrous oxide, as well as multiple electron donors that interact with these enzymes, in order to carry out the stepwise reactions that involve key intermediates. Because of the importance of this pathway (of parallel importance to the nitrogen-fixation pathway), efforts are underway to understand the structures of the participating enzymes and to uncover mechanistic aspects. Three-dimensional structures have been solved for the majority of these enzymes in the past few years, revealing the architecture of the active metal sites as well as global structural aspects, and possible mechanistic aspects. In addition, the recognition of specific electron-transfer partners raises important questions regarding specific electron-transfer pathways, partner recognition and control of metabolism.

Characteristics of summer and fall diurnal resting habitat used by American martens in coastal northwestern California

Treesearch

K. M. Slauson; W. J. Zielinski

2009-01-01

American martens use resting habitat between periods of activity to provide both thermal refugia and protection from predators. Maintenance or restoration of key elements of marten resting habitat, such as resting structures, requires that managers recognize their characteristics to protect them, or manage for their creation. We measured resting habitat at 4 scales: (1...

Overexpression of the class D MADS-box gene Sl-AGL11 impacts fleshy tissue differentiation and structure in tomato fruits

USDA-ARS?s Scientific Manuscript database

MADS-box transcription factors are key elements of the genetic networks controlling flower and fruit development. Among these, the class D clade are involved in seed, ovule, and funiculus development. The tomato genome comprises two class D genes, Sl-AGL11 and Sl-MBP3, both displaying high expressio...

We Can't Go Home Again: Insights from a Quarter Century of Experiments in External Academic Quality Assurance

ERIC Educational Resources Information Center

Dill, David D.

2010-01-01

What have we learned from 25 years of experience with external academic quality assurance that can help design more effective framework conditions for assuring academic standards? The key elements appear to be the structure and means of evaluating national academic quality assurance agencies, the nature of academic quality information mandated by…

Variable steroid receptor responses: Intrinsically disordered AF1 is the key

PubMed Central

Simons, S. Stoney; Kumar, Raj

2013-01-01

Steroid hormones, acting through their cognate receptor proteins, see widespread clinical applications due to their ability to alter the induction or repression of numerous genes. However, steroid usage is limited by the current inability to control off-target, or non-specific, side-effects. Recent results from three separate areas of research with glucocorticoid and other steroid receptors (cofactor-induced changes in receptor structure, the ability of ligands to alter remote regions of receptor structure, and how cofactor concentration affects both ligand potency and efficacy) indicate that a key element of receptor activity is the intrinsically disordered amino-terminal domain. These results are combined to construct a novel framework within which to logically pursue various approaches that could afford increased selectivity in steroid-based therapies. PMID:23792173

Motor programming when sequencing multiple elements of the same duration.

PubMed

Magnuson, Curt E; Robin, Donald A; Wright, David L

2008-11-01

Motor programming at the self-select paradigm was adopted in 2 experiments to examine the processing demands of independent processes. One process (INT) is responsible for organizing the internal features of the individual elements in a movement (e.g., response duration). The 2nd process (SEQ) is responsible for placing the elements into the proper serial order before execution. Participants in Experiment 1 performed tasks involving 1 key press or sequences of 4 key presses of the same duration. Implementing INT and SEQ was more time consuming for key-pressing sequences than for single key-press tasks. Experiment 2 examined whether the INT costs resulting from the increase in sequence length observed in Experiment 1 resulted from independent planning of each sequence element or via a separate "multiplier" process that handled repetitions of elements of the same duration. Findings from Experiment 2, in which participants performed single key presses or double or triple key sequences of the same duration, suggested that INT is involved with the independent organization of each element contained in the sequence. Researchers offer an elaboration of the 2-process account of motor programming to incorporate the present findings and the findings from other recent sequence-learning research.

Hepatitis B virus nuclear export elements: RNA stem-loop α and β, key parts of the HBV post-transcriptional regulatory element.

PubMed

Lim, Chun Shen; Brown, Chris M

2016-09-01

Many viruses contain RNA elements that modulate splicing and/or promote nuclear export of their RNAs. The RNAs of the major human pathogen, hepatitis B virus (HBV) contain a large (~600 bases) composite cis-acting 'post-transcriptional regulatory element' (PRE). This element promotes expression from these naturally intronless transcripts. Indeed, the related woodchuck hepadnavirus PRE (WPRE) is used to enhance expression in gene therapy and other expression vectors. These PRE are likely to act through a combination of mechanisms, including promotion of RNA nuclear export. Functional components of both the HBV PRE and WPRE are 2 conserved RNA cis-acting stem-loop (SL) structures, SLα and SLβ. They are within the coding regions of polymerase (P) gene, and both P and X genes, respectively. Based on previous studies using mutagenesis and/or nuclear magnetic resonance (NMR), here we propose 2 covariance models for SLα and SLβ. The model for the 30-nucleotide SLα contains a G-bulge and a CNGG(U) apical loop of which the first and the fourth loop residues form a CG pair and the fifth loop residue is bulged out, as observed in the NMR structure. The model for the 23-nucleotide SLβ contains a 7-base-pair stem and a 9-nucleotide loop. Comparison of the models with other RNA structural elements, as well as similarity searches of human transcriptome and viral genomes demonstrate that SLα and SLβ are specific to HBV transcripts. However, they are well conserved among the hepadnaviruses of non-human primates, the woodchuck and ground squirrel.

Hepatitis B virus nuclear export elements: RNA stem-loop α and β, key parts of the HBV post-transcriptional regulatory element

PubMed Central

Lim, Chun Shen; Brown, Chris M.

2016-01-01

ABSTRACT Many viruses contain RNA elements that modulate splicing and/or promote nuclear export of their RNAs. The RNAs of the major human pathogen, hepatitis B virus (HBV) contain a large (~600 bases) composite cis-acting 'post-transcriptional regulatory element' (PRE). This element promotes expression from these naturally intronless transcripts. Indeed, the related woodchuck hepadnavirus PRE (WPRE) is used to enhance expression in gene therapy and other expression vectors. These PRE are likely to act through a combination of mechanisms, including promotion of RNA nuclear export. Functional components of both the HBV PRE and WPRE are 2 conserved RNA cis-acting stem-loop (SL) structures, SLα and SLβ. They are within the coding regions of polymerase (P) gene, and both P and X genes, respectively. Based on previous studies using mutagenesis and/or nuclear magnetic resonance (NMR), here we propose 2 covariance models for SLα and SLβ. The model for the 30-nucleotide SLα contains a G-bulge and a CNGG(U) apical loop of which the first and the fourth loop residues form a CG pair and the fifth loop residue is bulged out, as observed in the NMR structure. The model for the 23-nucleotide SLβ contains a 7-base-pair stem and a 9-nucleotide loop. Comparison of the models with other RNA structural elements, as well as similarity searches of human transcriptome and viral genomes demonstrate that SLα and SLβ are specific to HBV transcripts. However, they are well conserved among the hepadnaviruses of non-human primates, the woodchuck and ground squirrel. PMID:27031749

Determinants of sustainability in solid waste management - The Gianyar Waste Recovery Project in Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zurbruegg, Christian, E-mail: zurbrugg@eawag.ch; Gfrerer, Margareth, E-mail: margareth.gfrerer@gmx.net; Ashadi, Henki, E-mail: henki@eng.ui.ac.id

2012-11-15

Highlights: Black-Right-Pointing-Pointer Our assessment tool helps evaluate success factors in solid waste projects. Black-Right-Pointing-Pointer Success of the composting plant in Indonesia is linked to its community integration. Black-Right-Pointing-Pointer Appropriate technology is not a main determining success factor for sustainability. Black-Right-Pointing-Pointer Structured assessment of 'best practices' can enhance replication in other cities. - Abstract: According to most experts, integrated and sustainable solid waste management should not only be given top priority, but must go beyond technical aspects to include various key elements of sustainability to ensure success of any solid waste project. Aside from project sustainable impacts, the overall enabling environmentmore » is the key feature determining performance and success of an integrated and affordable solid waste system. This paper describes a project-specific approach to assess typical success or failure factors. A questionnaire-based assessment method covers issues of: (i) social mobilisation and acceptance (social element), (ii) stakeholder, legal and institutional arrangements comprising roles, responsibilities and management functions (institutional element); (iii) financial and operational requirements, as well as cost recovery mechanisms (economic element). The Gianyar Waste Recovery Project in Bali, Indonesia was analysed using this integrated assessment method. The results clearly identified chief characteristics, key factors to consider when planning country wide replication but also major barriers and obstacles which must be overcome to ensure project sustainability. The Gianyar project consists of a composting unit processing 60 tons of municipal waste per day from 500,000 inhabitants, including manual waste segregation and subsequent composting of the biodegradable organic fraction.« less

Defining the conserved internal architecture of a protein kinase.

PubMed

Kornev, Alexandr P; Taylor, Susan S

2010-03-01

Protein kinases constitute a large protein family of important regulators in all eukaryotic cells. All of the protein kinases have a similar bilobal fold, and their key structural features have been well studied. However, the recent discovery of non-contiguous hydrophobic ensembles inside the protein kinase core shed new light on the internal organization of these molecules. Two hydrophobic "spines" traverse both lobes of the protein kinase molecule, providing a firm but flexible connection between its key elements. The spine model introduces a useful framework for analysis of intramolecular communications, molecular dynamics, and drug design. Published by Elsevier B.V.

Reflective learning in community-based dental education.

PubMed

Deogade, Suryakant C; Naitam, Dinesh

2016-01-01

Community-based dental education (CBDE) is the implementation of dental education in a specific social context, which shifts a substantial part of dental clinical education from dental teaching institutional clinics to mainly public health settings. Dental students gain additional value from CBDE when they are guided through a reflective process of learning. We propose some key elements to the existing CBDE program that support meaningful personal learning experiences. Dental rotations of 'externships' in community-based clinical settings (CBCS) are year-long community-based placements and have proven to be strong learning environments where students develop good communication skills and better clinical reasoning and management skills. We look at the characteristics of CBDE and how the social and personal context provided in communities enhances dental education. Meaningfulness is created by the authentic context, which develops over a period of time. Structured reflection assignments and methods are suggested as key elements in the existing CBDE program. Strategies to enrich community-based learning experiences for dental students include: Photographic documentation; written narratives; critical incident reports; and mentored post-experiential small group discussions. A directed process of reflection is suggested as a way to increase the impact of the community learning experiences. We suggest key elements to the existing CBDE module so that the context-rich environment of CBDE allows for meaningful relations and experiences for dental students and enhanced learning.

Geological Mapping Uses Landsat 4-5TM Satellite Data in Manlai Soum of Omnogovi Aimag

NASA Astrophysics Data System (ADS)

Norovsuren, B.

2014-12-01

Author: Bayanmonkh N1, Undram.G1, Tsolmon.R2, Ariunzul.Ya1, Bayartungalag B31 Environmental Research Information and Study Center 2NUM-ITC-UNESCO Space Science and Remote Sensing International Laboratory, National University of Mongolia 3Geology and Hydrology School, Korea University KEY WORDS: geology, mineral resources, fracture, structure, lithologyABSTRACTGeologic map is the most important map for mining when it does exploration job. In Mongolia geological map completed by Russian geologists which is done by earlier technology. Those maps doesn't satisfy for present requirements. Thus we want to study improve geological map which includes fracture, structural map and lithology use Landsat TM4-5 satellite data. If we can produce a geological map from satellite data with more specification then geologist can explain or read mineralogy very easily. We searched all methodology and researches of every single element of geological mapping. Then we used 3 different remote sensing methodologies to produce structural and lithology and fracture map based on geographic information system's softwares. There can be found a visible lithology border improvement and understandable structural map and we found fracture of the Russian geological map has a lot of distortion. The result of research geologist can read mineralogy elements very easy and discovered 3 unfound important elements from satellite image.

Synthesis of Novel 1,4- Dihydropyridine Derivatives Bearing Biphenyl-2'-Tetrazole Substitution as Potential Dual Angiotensin II Receptors and Calcium Channel Blockers

PubMed Central

Shahbazi Mojarrad, Javid; Zamani, Zahra; Nazemiyeh, Hossein; Ghasemi, Saeed; Asgari, Davoud

2011-01-01

Introduction: We report the synthesis of novel 1,4-dihydropyridine derivatives containing biphenyl-2'-tetrazole moieties. We hypothesized that merging the key structural elements present in an AT1 receptor antagonist with key structural elements in 1,4-dihydropyridine calcium channel blockers would yield novel analogs with potential dual activity for both receptors. This strategy led to the design and synthesis of dialkyl 1,4-dihydro-2,6-dimethyl-4-[2-n-alkyl-1-[2΄-(1H-tetrazole-5-yl) biphenyl -4-yl] methyl] imidazole-4(or 5)-yl]- 3, 5-pyridinedicarboxylate analogs. Methods: These compounds were obtained by two methods starting from biphenyltetrazolyl-4-(or 5)-imidazolecarboxaldehyde intermediates employing in classical Hantzsch condensation reaction. In the first method, triphenylmethyl protecting group of 4- or 5-carboxaldehyde intermediate was first removed in acidic media and then classical Hantzsch reaction was employed in order to obtain the final products. In the second method, without further deprotection process, protected 4- or 5-carboxaldehyde intermediate directly was used in Hantzsch reaction. Results: The second method was more efficient than the first method since the deprotection and ring closure reaction occurs simultaneously in one pot. Conclusion: Eight novel dihydropridines analogs were synthesized using classic Hantzsch condensation reaction. Chemical structures of the compounds were characterized by 1H NMR, infrared and mass spectroscopy. PMID:24312750

Perforated Pit Membranes in Imperforate Tracheary Elements of Some Angiosperms

PubMed Central

SANO, YUZOU; JANSEN, STEVEN

2006-01-01

• Background and Aims The structure of pit membranes in angiosperms has not been fully examined and our understanding about the structure is incomplete. Therefore, this study aims to illustrate the micromorphology of pit membranes in fibres and tracheids of woody species from various families. • Methods Specimens from ten species from ten genera and eight families were prepared using two techniques and examined by field-emission scanning electron microscopy. • Key Results Interfibre pit membranes with an average diameter of <4 µm were frequently perforated or appeared to be very porous. In contrast, pit membranes in imperforate tracheary elements with distinctly bordered pits and an average diameter of ≥4 µm were homogeneous and densely packed with microfibrils. These differences were observed consistently not only among species but also within a single species in which different types of imperforate tracheary elements were present. • Conclusions This study demonstrates that the structure of interfibre pit membranes differs among cell types and the differences are closely associated with the specialization of the fibre cells. It is suggested that perforated pit membranes between specialized fibres contribute to the dehydration of the fibre cells at or soon after maturation. PMID:16520339

An Overview of Integration and Test of the James Webb Space Telescope Integrated Science Instrument Module

NASA Technical Reports Server (NTRS)

Drury, Michael; Becker, Neil; Bos, Brent; Davila, Pamela; Frey, Bradley; Hylan, Jason; Marsh, James; McGuffey, Douglas; Novak, Maria; Ohl, Raymond;

Crystal Structure Predictions Using Adaptive Genetic Algorithm and Motif Search methods

NASA Astrophysics Data System (ADS)

Ho, K. M.; Wang, C. Z.; Zhao, X.; Wu, S.; Lyu, X.; Zhu, Z.; Nguyen, M. C.; Umemoto, K.; Wentzcovitch, R. M. M.

2017-12-01

Material informatics is a new initiative which has attracted a lot of attention in recent scientific research. The basic strategy is to construct comprehensive data sets and use machine learning to solve a wide variety of problems in material design and discovery. In pursuit of this goal, a key element is the quality and completeness of the databases used. Recent advance in the development of crystal structure prediction algorithms has made it a complementary and more efficient approach to explore the structure/phase space in materials using computers. In this talk, we discuss the importance of the structural motifs and motif-networks in crystal structure predictions. Correspondingly, powerful methods are developed to improve the sampling of the low-energy structure landscape.

Structure of a prokaryotic sodium channel pore reveals essential gating elements and an outer ion binding site common to eukaryotic channels.

PubMed

Shaya, David; Findeisen, Felix; Abderemane-Ali, Fayal; Arrigoni, Cristina; Wong, Stephanie; Nurva, Shailika Reddy; Loussouarn, Gildas; Minor, Daniel L

2014-01-23

Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail "neck", are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the "outer ion" site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies, shows that this site forms a previously unknown determinant of CaV high-affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily. © 2013. Published by Elsevier Ltd. All rights reserved.

Free-energy simulations reveal molecular mechanism for functional switch of a DNA helicase

PubMed Central

Ma, Wen; Whitley, Kevin D; Schulten, Klaus

2018-01-01

Helicases play key roles in genome maintenance, yet it remains elusive how these enzymes change conformations and how transitions between different conformational states regulate nucleic acid reshaping. Here, we developed a computational technique combining structural bioinformatics approaches and atomic-level free-energy simulations to characterize how the Escherichia coli DNA repair enzyme UvrD changes its conformation at the fork junction to switch its function from unwinding to rezipping DNA. The lowest free-energy path shows that UvrD opens the interface between two domains, allowing the bound ssDNA to escape. The simulation results predict a key metastable 'tilted' state during ssDNA strand switching. By simulating FRET distributions with fluorophores attached to UvrD, we show that the new state is supported quantitatively by single-molecule measurements. The present study deciphers key elements for the 'hyper-helicase' behavior of a mutant and provides an effective framework to characterize directly structure-function relationships in molecular machines. PMID:29664402

Free-energy simulations reveal molecular mechanism for functional switch of a DNA helicase.

PubMed

Ma, Wen; Whitley, Kevin D; Chemla, Yann R; Luthey-Schulten, Zaida; Schulten, Klaus

2018-04-17

Helicases play key roles in genome maintenance, yet it remains elusive how these enzymes change conformations and how transitions between different conformational states regulate nucleic acid reshaping. Here, we developed a computational technique combining structural bioinformatics approaches and atomic-level free-energy simulations to characterize how the Escherichia coli DNA repair enzyme UvrD changes its conformation at the fork junction to switch its function from unwinding to rezipping DNA. The lowest free-energy path shows that UvrD opens the interface between two domains, allowing the bound ssDNA to escape. The simulation results predict a key metastable 'tilted' state during ssDNA strand switching. By simulating FRET distributions with fluorophores attached to UvrD, we show that the new state is supported quantitatively by single-molecule measurements. The present study deciphers key elements for the 'hyper-helicase' behavior of a mutant and provides an effective framework to characterize directly structure-function relationships in molecular machines. © 2018, Ma et al.

Queued History based Mediator Identification for an Incentive Attached peer to peer Electronic Coupon System

NASA Astrophysics Data System (ADS)

Shojima, Taiki; Ikkai, Yoshitomo; Komoda, Norihisa

An incentive attached peer to peer (P2P) electronic coupon system is proposed in which users forward e-coupons to potential users by providing incentives to those mediators. A service provider needs to acquire distribution history for incentive payment by recording UserIDs (UIDs) in the e-coupons, since this system is intended for pure P2P environment. This causes problems of dishonestly altering distribution history. In order to solve such problems, distribution history is realized in a couple of queues structure. They are the UID queue, and the public key queue. Each element of the UID queue at the initial state consists of index, a secret key, and a digital signature. In recording one's UID, the encrypted UID is enqueued to the UID queue with a new digital signature created by a secret key of the dequeued element, so that each UID cannot be altered. The public key queue provides the functionality of validating digital signatures on mobile devices. This method makes it possible both each UID and sequence of them to be certificated. The availability of the method is evaluated by quantifying risk reduction using Fault Tree Analysis (FTA). And it's recognized that the method is better than common encryption methods.

A tensegrity model for hydrogen bond networks in proteins.

PubMed

Bywater, Robert P

2017-05-01

Hydrogen-bonding networks in proteins considered as structural tensile elements are in balance separately from any other stabilising interactions that may be in operation. The hydrogen bond arrangement in the network is reminiscent of tensegrity structures in architecture and sculpture. Tensegrity has been discussed before in cells and tissues and in proteins. In contrast to previous work only hydrogen bonds are studied here. The other interactions within proteins are either much stronger - covalent bonds connecting the atoms in the molecular skeleton or weaker forces like the so-called hydrophobic interactions. It has been demonstrated that the latter operate independently from hydrogen bonds. Each category of interaction must, if the protein is to have a stable structure, balance out. The hypothesis here is that the entire hydrogen bond network is in balance without any compensating contributions from other types of interaction. For sidechain-sidechain, sidechain-backbone and backbone-backbone hydrogen bonds in proteins, tensegrity balance ("closure") is required over the entire length of the polypeptide chain that defines individually folding units in globular proteins ("domains") as well as within the repeating elements in fibrous proteins that consist of extended chain structures. There is no closure to be found in extended structures that do not have repeating elements. This suggests an explanation as to why globular domains, as well as the repeat units in fibrous proteins, have to have a defined number of residues. Apart from networks of sidechain-sidechain hydrogen bonds there are certain key points at which this closure is achieved in the sidechain-backbone hydrogen bonds and these are associated with demarcation points at the start or end of stretches of secondary structure. Together, these three categories of hydrogen bond achieve the closure that is necessary for the stability of globular protein domains as well as repeating elements in fibrous proteins.

Nature Elements and Fundamental Motor Skill Development Opportunities at Five Elementary School Districts in British Columbia

PubMed Central

Lim, Christopher; Donovan, Andrew M.; Naylor, Patti-Jean

2017-01-01

The majority of Canadian children are not physically active enough for healthy development. School playgrounds are a primary location to promote physical activity and motor skill practice. The benefits of children’s play in nature have also been highlighted, but few studies have evaluated children’s access and exposure to nature for play on school grounds. This study examined children’s access to nature on school grounds and the opportunities afforded by those natural elements for motor skill practice. Results: Extensive naturescapes (multiple nature elements in one setting) were not common, and natural elements were limited, ranging from 1.97 to 5.71 elements/school. The most common element was a forested area (26.5% of all natural elements identified). In comparison to built structures, the number of natural elements was low. Some elements differed between school districts and appeared to be related to local geography and terrain (hilly, rocky terrain, tidal flats, etc.). Our assessment showed that naturescape elements afforded opportunities for the development of some key fundamental motor skills (FMS), specifically, locomotor and stability skills, but opportunities to develop manipulative skills were limited. To maximize potential FMS development, physical literacy, and psycho-social benefits, additional elements or more comprehensive multi-element naturescapes and facilitation (social or environmental) are recommended. PMID:29064430

Nature Elements and Fundamental Motor Skill Development Opportunities at Five Elementary School Districts in British Columbia.

PubMed

Lim, Christopher; Donovan, Andrew M; Harper, Nevin J; Naylor, Patti-Jean

2017-10-24

The majority of Canadian children are not physically active enough for healthy development. School playgrounds are a primary location to promote physical activity and motor skill practice. The benefits of children's play in nature have also been highlighted, but few studies have evaluated children's access and exposure to nature for play on school grounds. This study examined children's access to nature on school grounds and the opportunities afforded by those natural elements for motor skill practice. Extensive naturescapes (multiple nature elements in one setting) were not common, and natural elements were limited, ranging from 1.97 to 5.71 elements/school. The most common element was a forested area (26.5% of all natural elements identified). In comparison to built structures, the number of natural elements was low. Some elements differed between school districts and appeared to be related to local geography and terrain (hilly, rocky terrain, tidal flats, etc.). Our assessment showed that naturescape elements afforded opportunities for the development of some key fundamental motor skills (FMS), specifically, locomotor and stability skills, but opportunities to develop manipulative skills were limited. To maximize potential FMS development, physical literacy, and psycho-social benefits, additional elements or more comprehensive multi-element naturescapes and facilitation (social or environmental) are recommended.

Obesity resistance and deregulation of lipogenesis in Δ6-fatty acid desaturase (FADS2) deficiency.

PubMed

Stoffel, Wilhelm; Hammels, Ina; Jenke, Britta; Binczek, Erika; Schmidt-Soltau, Inga; Brodesser, Susanne; Odenthal, Margarete; Thevis, Mario

2014-01-01

Δ-6-fatty acid desaturase (FADS2) is the key enzyme in the biosynthesis of polyunsaturated fatty acids (PUFAs), the essential structural determinants of mammalian membrane lipid-bilayers. We developed the auxotrophic fads2(-/-) mouse mutant to assess the enigmatic role of ω3- and ω6-PUFAs in lipid homeostasis, membrane structure and function. Obesity resistance is another major phenotype of the fads2(-/-) mutant, the molecular basis of which is unknown. Phospholipidomic profiling of membrane systems of fads2(-/-)mice revealed diacylglycerol-structures, deprived of PUFAs but substituted with surrogate eicosa-5,11,14-trienoic acid. ω6-Arachidonic (AA) and ω3-docosahexaenoic acid (DHA) supplemented diets transformed fads2(-/-) into AA-fads2(-/-) and DHA-fads2(-/-) mutants. Severely altered phospholipid-bilayer structures of subcellular membranes of fads2(-/-) liver specifically interfered with maturation of transcription factor sterol-regulatory-element-binding protein, the key regulator of lipogenesis and lipid homeostasis. This study strengthens the concept that specific PUFA-substituted membrane phospholipid species are critical constituents of the structural platform operative in lipid homeostasis in normal and disease conditions.

Capturing structured, pulmonary disease-specific data elements in electronic health records.

PubMed

Gronkiewicz, Cynthia; Diamond, Edward J; French, Kim D; Christodouleas, John; Gabriel, Peter E

2015-04-01

Electronic health records (EHRs) have the potential to improve health-care quality by allowing providers to make better decisions at the point of care based on electronically aggregated data and by facilitating clinical research. These goals are easier to achieve when key, disease-specific clinical information is documented as structured data elements (SDEs) that computers can understand and process, rather than as free-text/natural-language narrative. This article reviews the benefits of capturing disease-specific SDEs. It highlights several design and implementation considerations, including the impact on efficiency and expressivity of clinical documentation and the importance of adhering to data standards when available. Pulmonary disease-specific examples of collection instruments are provided from two commonly used commercial EHRs. Future developments that can leverage SDEs to improve clinical quality and research are discussed.

High frequency copolymer ultrasonic transducer array of size-effective elements

NASA Astrophysics Data System (ADS)

Decharat, Adit; Wagle, Sanat; Habib, Anowarul; Jacobsen, Svein; Melandsø, Frank

2018-02-01

A layer-by-layer deposition method for producing dual-layer ultrasonic transducers from piezoelectric copolymers has been developed. The method uses a combination of customized and standard processing to obtain 2D array transducers with electrical connection of the individual elements routed directly to the rear of the substrate. A numerical model was implemented to study basic parameters effecting the transducer characteristics. Key elements of the array were characterized and evaluated, demonstrating its viability of 2D imaging. Signal reproducibility of the prototype array was studied by characterizing the variations of the center frequency (≈42 MHz) and bandwidth (≈25 MHz) of the acoustic. Object identification was also tested and parameterized by acoustic-field beamwidth as well as proper scan step size. Simple tests to illustrate a benefit of multi-element scan on lowering the inspection time were conducted. Structural imaging of the test structure underneath multi-layered wave media (glass plate and distilled water) was also performed. The prototype presented in this work is an important step towards realizing an inexpensive, compact array of individually operated copolymer transducers that can serve in a fast/volumetric high frequency (HF) ultrasonic scanning platform.

Long‐term monitoring reveals differing impacts of elephants on elements of a canopy shrub community.

PubMed

Landman, Marietjie; Schoeman, David S; Hall-Martin, Anthony J; Kerley, Graham I H

The conservation management of southern Africa's elephants focuses on identifying and mitigating the extent and intensity of impacts on biological diversity. However, variation in the intensity of elephant effects between elements of biodiversity is seldom explored, which limits our ability to interpret the scale of the impacts. Our study quantifies >50 years of impacts in the succulent thickets of the Addo Elephant National Park, South Africa, contrasting hypotheses for the resilience of the canopy shrubs (a key functional guild) to elephants with those that argue the opposite. We also assess the impacts between elements of the community, ranging from community composition and structure to the structure of individual canopy species. We show the vulnerability of the canopy shrubs to transformation as the accumulated influences of elephants alter community composition and structure. The pattern of transformation is similar to that caused by domestic herbivores, which leads us to predict that elephants will eventually bring about landscape-level degradation and a significant loss of biodiversity. While we expected the canopy species to show similar declining trends in structure, providing insight into the response of the community as a whole, we demonstrate an uneven distribution of impacts between constituent elements; most of the canopy dominants exhibited little change, resisting removal. This implies that these canopy dominants might not be useful indicators of community change in thickets, a pattern that is likely repeated among the canopy trees of savanna systems. Our findings suggest that predicting elephant impacts, and finding solutions to the so-called “elephant problem,” require a broader and more integrated understanding of the mechanisms driving the changes between elements of biodiversity at various spatial and temporal scales.

Grouping Within Algebra I: A Structural Sieve With Powerful Effects for Low-Income, Minority, and Immigrant Students

ERIC Educational Resources Information Center

Paul, Faith G.

2005-01-01

A key element in educational reform has been to increase mathematical proficiency. We look at how five urban high schools with virtually all low-income, minority, and immigrant students have arranged for students to take algebra I, and we examine the course enrollments and grades of these student in the core college prep courses. Both preparation…

Pseudomorphic InGaAs Materials

DTIC Science & Technology

1990-07-31

tive mass Schrodinger equation can be cast using a finite element technique (Galerkin residual method) into a symmetric tridiagonal matrix formulation...lnr’Gal-.’As composition. All of the structures were fabricated by molecular beam epitaxy (MBE). The effects of different growth conditions were evaluated... different growth conditions were evaluated with a combination of characterization techniques. Key results to emerge from this work relate to the

A conceptual view for advancing monitoring and assessment of land resources in the Mexican state of Jalisco

Treesearch

Celedonio Aguirre-Bravo

2006-01-01

This paper addresses key elements of a conceptual view for advancing monitoring and a variety of applications to land resources and environmental management in the state of Jalisco, Mexico. Fundamental to this conceptual view is what we know about the structure and functioning of nature: the spatial and temporal dynamics of processes (for example, objects, outcomes),...

The "critical limits for crystallinity" in nanoparticles of the elements: A combined thermodynamic and crystallographic critique

NASA Astrophysics Data System (ADS)

Pelegrina, J. L.; Guillermet, A. Fernández

2018-03-01

The theme of the present work is the procedure for evaluating the minimum size for the stability of a crystalline particle with respect to the same group of atoms but in the amorphous state. A key goal of the study is the critical analysis of an extensively quoted paper by F.G. Shi [J. Mater. Res. 9 (1994) 1307-1313], who presented a criterion for evaluating a "crystallinity distance" (h) through its relation with the "critical diameter" (dC) of a particle, i.e., the diameter below which no particles with the crystalline structure are expected to exist at finite temperatures. Key assumptions of Shi's model are a direct proportionality relation between h and dC , and a prescription for estimating h from crystallographic information. In the present work the accuracy of the Shi model is assessed with particular reference to nanoparticles of the elements. To this end, an alternative way to obtain h, that better realizes Shi's idea of this quantity as "the height of a monolayer of atoms on the bulk crystal surface", is explored. Moreover, a thermodynamic calculation of dC , which involves a description of the bulk- and the surface contributions to the crystalline/amorphous relative phase stability for nanoparticles, is performed. It is shown that the Shi equation does not account for the key features of the h vs. dC relation established in the current work. Consequently, it is concluded that the parameter h obtained only from information about the structure of the crystalline phase, does not provide an accurate route to estimate the quantity dC . In fact, a key result of the current study is that dC crucially depends on the relation between bulk- and surface contributions to the crystalline/amorphous relative thermodynamic stability.

An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures

PubMed Central

Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf

2016-01-01

Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762

Automated analysis in generic groups

NASA Astrophysics Data System (ADS)

Fagerholm, Edvard

This thesis studies automated methods for analyzing hardness assumptions in generic group models, following ideas of symbolic cryptography. We define a broad class of generic and symbolic group models for different settings---symmetric or asymmetric (leveled) k-linear groups --- and prove ''computational soundness'' theorems for the symbolic models. Based on this result, we formulate a master theorem that relates the hardness of an assumption to solving problems in polynomial algebra. We systematically analyze these problems identifying different classes of assumptions and obtain decidability and undecidability results. Then, we develop automated procedures for verifying the conditions of our master theorems, and thus the validity of hardness assumptions in generic group models. The concrete outcome is an automated tool, the Generic Group Analyzer, which takes as input the statement of an assumption, and outputs either a proof of its generic hardness or shows an algebraic attack against the assumption. Structure-preserving signatures are signature schemes defined over bilinear groups in which messages, public keys and signatures are group elements, and the verification algorithm consists of evaluating ''pairing-product equations''. Recent work on structure-preserving signatures studies optimality of these schemes in terms of the number of group elements needed in the verification key and the signature, and the number of pairing-product equations in the verification algorithm. While the size of keys and signatures is crucial for many applications, another aspect of performance is the time it takes to verify a signature. The most expensive operation during verification is the computation of pairings. However, the concrete number of pairings is not captured by the number of pairing-product equations considered in earlier work. We consider the question of what is the minimal number of pairing computations needed to verify structure-preserving signatures. We build an automated tool to search for structure-preserving signatures matching a template. Through exhaustive search we conjecture lower bounds for the number of pairings required in the Type~II setting and prove our conjecture to be true. Finally, our tool exhibits examples of structure-preserving signatures matching the lower bounds, which proves tightness of our bounds, as well as improves on previously known structure-preserving signature schemes.

What determines the spectrum of protein native state structures?

PubMed

Lezon, Timothy R; Banavar, Jayanth R; Lesk, Arthur M; Maritan, Amos

2006-05-01

We present a brief summary of the key factors underlying protein structure, as developed in the investigations of Pauling, Ramachandran, and Rose. We then outline a simplified physical model of proteins that focuses on geometry and symmetry. Although this model superficially appears unrelated to the detailed chemical descriptions commonly applied to proteins, we show that it captures the essential elements of the chemistry and provides a unified framework for understanding the common characteristics of folded proteins. We suggest that the spectrum of protein native state structures is determined by geometry and symmetry and the role of the sequence is to choose its native state structure from this predetermined menu. 2006 Wiley-Liss, Inc.

Microplate and shear zone models for oceanic spreading center reorganizations

NASA Technical Reports Server (NTRS)

Engeln, Joseph F.; Stein, Seth; Werner, John; Gordon, Richard

1988-01-01

The kinematics of rift propagation and the resulting goemetries of various tectonic elements for two plates is reviewed with no overlap zone. The formation and evolution of overlap regions using schematic models is discussed. The models are scaled in space and time to approximate the Easter plate, but are simplified to emphasize key elements. The tectonic evolution of overlap regions which act as rigid microplates and shear zones is discussed, and the use of relative motion and structural data to discriminate between the two types of models is investigated. The effect of propagation rate and rise time on the size, shape, and deformation of the overlap region is demonstrated.

Structured representation for core elements of common clinical decision support interventions to facilitate knowledge sharing.

PubMed

Zhou, Li; Hongsermeier, Tonya; Boxwala, Aziz; Lewis, Janet; Kawamoto, Kensaku; Maviglia, Saverio; Gentile, Douglas; Teich, Jonathan M; Rocha, Roberto; Bell, Douglas; Middleton, Blackford

2013-01-01

At present, there are no widely accepted, standard approaches for representing computer-based clinical decision support (CDS) intervention types and their structural components. This study aimed to identify key requirements for the representation of five widely utilized CDS intervention types: alerts and reminders, order sets, infobuttons, documentation templates/forms, and relevant data presentation. An XML schema was proposed for representing these interventions and their core structural elements (e.g., general metadata, applicable clinical scenarios, CDS inputs, CDS outputs, and CDS logic) in a shareable manner. The schema was validated by building CDS artifacts for 22 different interventions, targeted toward guidelines and clinical conditions called for in the 2011 Meaningful Use criteria. Custom style sheets were developed to render the XML files in human-readable form. The CDS knowledge artifacts were shared via a public web portal. Our experience also identifies gaps in existing standards and informs future development of standards for CDS knowledge representation and sharing.

Structure of a bacterial RNA polymerase holoenzyme open promoter complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, Brian; Feklistov, Andrey; Lass-Napiorkowska, Agnieszka

2015-09-08

Initiation of transcription is a primary means for controlling gene expression. In bacteria, the RNA polymerase (RNAP) holoenzyme binds and unwinds promoter DNA, forming the transcription bubble of the open promoter complex (RPo). We have determined crystal structures, refined to 4.14 Å-resolution, of RPo containing Thermus aquaticus RNAP holoenzyme and promoter DNA that includes the full transcription bubble. The structures, combined with biochemical analyses, reveal key features supporting the formation and maintenance of the double-strand/single-strand DNA junction at the upstream edge of the -10 element where bubble formation initiates. The results also reveal RNAP interactions with duplex DNA just upstreammore » of the -10 element and potential protein/DNA interactions that direct the DNA template strand into the RNAP active site. Addition of an RNA primer to yield a 4 base-pair post-translocated RNA:DNA hybrid mimics an initially transcribing complex at the point where steric clash initiates abortive initiation and σA dissociation.« less

Structure of a bacterial RNA polymerase holoenzyme open promoter complex

DOE PAGES

Bae, Brian; Feklistov, Andrey; Lass-Napiorkowska, Agnieszka; ...

2015-09-08

Initiation of transcription is a primary means for controlling gene expression. In bacteria, the RNA polymerase (RNAP) holoenzyme binds and unwinds promoter DNA, forming the transcription bubble of the open promoter complex (RPo). We have determined crystal structures, refined to 4.14 Å-resolution, of RPo containing Thermus aquaticus RNAP holoenzyme and promoter DNA that includes the full transcription bubble. The structures, combined with biochemical analyses, reveal key features supporting the formation and maintenance of the double-strand/single-strand DNA junction at the upstream edge of the -10 element where bubble formation initiates. The results also reveal RNAP interactions with duplex DNA just upstreammore » of the -10 element and potential protein/DNA interactions that direct the DNA template strand into the RNAP active site. Additionally a RNA primer to yield a 4 base-pair post-translocated RNA:DNA hybrid mimics an initially transcribing complex at the point where steric clash initiates abortive initiation and σ A dissociation.« less

Biomimetric sentinel reef structures for optical sensing and communications

NASA Astrophysics Data System (ADS)

Fries, David; Hutcheson, Tim; Josef, Noam; Millie, David; Tate, Connor

2017-05-01

Traditional artificial reef structures are designed with uniform cellular architectures and topologies and do not mimic natural reef forms. Strings and ropes are a proven, common fisheries and mariculture construction element throughout the world and using them as artificial reef scaffolding can enable a diversity of ocean sensing, communications systems including the goal of sentinel reefs. The architecture and packaging of electronics is key to enabling such structures and systems. The distributed sensor reef concept leads toward a demonstrable science-engineering-informed framework for 3D smart habitat designs critical to stock fish development and coastal monitoring and protection. These `nature-inspired' reef infrastructures, can enable novel instrumented `reef observatories' capable of collecting real-time ecosystem data. Embedding lighting and electronic elements into artificial reef systems are the first systems conceptualized. This approach of bringing spatial light to the underwater world for optical sensing, communication and even a new breed of underwater robotic vehicle is an interdisciplinary research activity which integrates principles of electronic packaging, and ocean technology with art/design.

Fine Structure of Plasmaspheric Hiss

NASA Astrophysics Data System (ADS)

Summers, D.; Omura, Y.; Nakamura, S.; Kletzing, C.

2014-12-01

Plasmaspheric hiss plays a key role in controlling the structure and dynamics of Earth's radiation belts.The quiet time slot region between the inner and outer belts can be explained as a steady-state balance between earthward radial diffusion and pitch-angle scattering loss of energetic electrons to the atmosphere induced by plasmaspheric hiss. Plasmaspheric hiss can also induce gradual precipitation loss of MeV electrons from the outer radiation belt. Plasmaspheric hiss has been widely regarded as a broadband,structureless,incoherent emission. Here, by examining burst-mode vector waveform data from the EMFISIS instrument on the Van Allen Probes mission,we show that plasmaspheric hiss is a coherent emission with complex fine structure. Specifically, plasmaspheric hiss appears as discrete rising tone and falling tone elements. By means of waveform analysis we identify typical amplitudes,phase profiles,and sweep rates of the rising and falling tone elements. The new observations reported here can be expected to fuel a re-examination of the properties of plasmaspheric hiss, including a further re-analysis of the generation mechanism for hiss.

Physics of primordial star formation

NASA Astrophysics Data System (ADS)

Yoshida, Naoki

2012-09-01

The study of primordial star formation has a history of nearly sixty years. It is generally thought that primordial stars are one of the key elements in a broad range of topics in astronomy and cosmology, from Galactic chemical evolution to the formation of super-massive blackholes. We review recent progress in the theory of primordial star formation. The standard theory of cosmic structure formation posits that the present-day rich structure of the Universe developed through gravitational amplification of tiny matter density fluctuations left over from the Big Bang. It has become possible to study primordial star formation rigorously within the framework of the standard cosmological model. We first lay out the key physical processes in a primordial gas. Then, we introduce recent developments in computer simulations. Finally, we discuss prospects for future observations of the first generation of stars.

New families of human regulatory RNA structures identified by comparative analysis of vertebrate genomes.

PubMed

Parker, Brian J; Moltke, Ida; Roth, Adam; Washietl, Stefan; Wen, Jiayu; Kellis, Manolis; Breaker, Ronald; Pedersen, Jakob Skou

2011-11-01

Regulatory RNA structures are often members of families with multiple paralogous instances across the genome. Family members share functional and structural properties, which allow them to be studied as a whole, facilitating both bioinformatic and experimental characterization. We have developed a comparative method, EvoFam, for genome-wide identification of families of regulatory RNA structures, based on primary sequence and secondary structure similarity. We apply EvoFam to a 41-way genomic vertebrate alignment. Genome-wide, we identify 220 human, high-confidence families outside protein-coding regions comprising 725 individual structures, including 48 families with known structural RNA elements. Known families identified include both noncoding RNAs, e.g., miRNAs and the recently identified MALAT1/MEN β lincRNA family; and cis-regulatory structures, e.g., iron-responsive elements. We also identify tens of new families supported by strong evolutionary evidence and other statistical evidence, such as GO term enrichments. For some of these, detailed analysis has led to the formulation of specific functional hypotheses. Examples include two hypothesized auto-regulatory feedback mechanisms: one involving six long hairpins in the 3'-UTR of MAT2A, a key metabolic gene that produces the primary human methyl donor S-adenosylmethionine; the other involving a tRNA-like structure in the intron of the tRNA maturation gene POP1. We experimentally validate the predicted MAT2A structures. Finally, we identify potential new regulatory networks, including large families of short hairpins enriched in immunity-related genes, e.g., TNF, FOS, and CTLA4, which include known transcript destabilizing elements. Our findings exemplify the diversity of post-transcriptional regulation and provide a resource for further characterization of new regulatory mechanisms and families of noncoding RNAs.

A continuum model for dynamic analysis of the Space Station

NASA Technical Reports Server (NTRS)

Thomas, Segun

1989-01-01

Dynamic analysis of the International Space Station using MSC/NASTRAN had 1312 rod elements, 62 beam elements, 489 nodes and 1473 dynamic degrees of freedom. A realtime, man-in-the-loop simulation of such a model is impractical. This paper discusses the mathematical model for realtime dynamic simulation of the Space Station. Several key questions in structures and structural dynamics are addressed. First, to achieve a significant reduction in the number of dynamic degrees of freedom, a continuum equivalent representation of the Space Station truss structure which accounted for the unsymmetry of the basic configuration and resulted in the coupling of extensional and transverse deformation, is developed. Next, dynamic equations for the continuum equivalent of the Space Station truss structure are formulated using a matrix version of Kane's dynamical equations. Flexibility is accounted for by using a theory that accommodates extension, bending in two principal planes and shear displacement. Finally, constraint equations suitable for dynamic analysis of flexible bodies with closed loop configuration are developed and solution of the resulting system of equations is based on the zero eigenvalue theorem.

Integration of magnetic bearings in the design of advanced gas turbine engines

NASA Technical Reports Server (NTRS)

Storace, Albert F.; Sood, Devendra K.; Lyons, James P.; Preston, Mark A.

1994-01-01

Active magnetic bearings provide revolutionary advantages for gas turbine engine rotor support. These advantages include tremendously improved vibration and stability characteristics, reduced power loss, improved reliability, fault-tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural network design and advanced materials utilization will permit major increases in thrust to weight performance and structural efficiency for future gas turbine engines. However, obtaining the maximum payoff requires two key ingredients. The first key ingredient is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-density power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies. The second key ingredient is to go beyond the simple replacement of rolling element bearings with magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper approach to designing with composites, whereby the designer tailors the geometry and load carrying function of the structural system or component for the composite instead of simply substituting composites in a design originally intended for metal material. This paper describes methodologies for the design integration of magnetic bearings in gas turbine engines.

Structural imprints in vivo decode RNA regulatory mechanisms

PubMed Central

Spitale, Robert C.; Flynn, Ryan A.; Zhang, Qiangfeng Cliff; Crisalli, Pete; Lee, Byron; Jung, Jong-Wha; Kuchelmeister, Hannes Y.; Batista, Pedro J.; Torre, Eduardo A.; Kool, Eric T.; Chang, Howard Y.

2015-01-01

Visualizing the physical basis for molecular behavior inside living cells is a grand challenge in biology. RNAs are central to biological regulation, and RNA’s ability to adopt specific structures intimately controls every step of the gene expression program1. However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles view only two of four nucleotides that make up RNA2,3. Here we present a novel biochemical approach, In Vivo Click SHAPE (icSHAPE), that enables the first global view of RNA secondary structures of all four bases in living cells. icSHAPE of mouse embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguishes different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved from in vitro, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA binding proteins or RNA modification sites that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N6-methyladenosine (m6A) modification genome-wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression. PMID:25799993

Structural imprints in vivo decode RNA regulatory mechanisms.

PubMed

Spitale, Robert C; Flynn, Ryan A; Zhang, Qiangfeng Cliff; Crisalli, Pete; Lee, Byron; Jung, Jong-Wha; Kuchelmeister, Hannes Y; Batista, Pedro J; Torre, Eduardo A; Kool, Eric T; Chang, Howard Y

2015-03-26

Visualizing the physical basis for molecular behaviour inside living cells is a great challenge for biology. RNAs are central to biological regulation, and the ability of RNA to adopt specific structures intimately controls every step of the gene expression program. However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles include only two of the four nucleotides that make up RNA. Here we present a novel biochemical approach, in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE), which enables the first global view, to our knowledge, of RNA secondary structures in living cells for all four bases. icSHAPE of the mouse embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguish different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved from in vitro conditions, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA-binding proteins or RNA-modification sites that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N(6)-methyladenosine (m(6)A) modification genome wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression.

Post-disaster Gulf Coast Recovery Using Telehealth

PubMed Central

Kim, Thomas J.; Eastburn, Sasha L.; Icenogle, Marjorie L.; Slagle, Michelle; Nuriddin, Azizeh H.; Brantley, Katrina M.; Foreman, Rachel D.; Buckner, Ayanna V.

2013-01-01

Abstract Objective: The Gulf Coast continues to struggle with service need far outpacing available resources. Since 2005, the Regional Coordinating Center for Hurricane Response (RCC) at Morehouse School of Medicine, Atlanta, GA, has supported telehealth solutions designed to meet high service needs (e.g., psychiatry) within primary care and other healthcare organizations. The overall RCC vision is to support autonomous, useful, and sustainable telehealth programs towards mitigating unmet disaster-related needs. Subjects and Methods: To assess Gulf Coast telehealth experiences, we conducted semistructured interviews with both regional key informants and national organizations with Gulf Coast recovery interests. Using qualitative-descriptive analysis, interview transcripts were analyzed to identify shared development themes. Results: Thirty-eight key informants were interviewed, representing a 77.6% participation rate among organizations engaged by the RCC. Seven elements critical to telehealth success were identified: Funding, Regulatory, Workflow, Attitudes, Personnel, Technology, and Evaluation. These key informant accounts reveal shared insights with telehealth regarding successes, challenges, and recommendations. Conclusions: The seven elements critical to telehealth success both confirm and organize development principles from a diverse collective of healthcare stakeholders. The structured nature of these insights suggests a generalizable framework upon which other organizations might develop telehealth strategies toward addressing high service needs with limited resources. PMID:23427981

Elemental and isotopic imaging to study biogeochemical functioning of intact soil micro-environments

NASA Astrophysics Data System (ADS)

Mueller, Carsten W.

2017-04-01

The complexity of soils extends from the ecosystem-scale to individual micro-aggregates, where nano-scale interactions between biota, organic matter (OM) and mineral particles are thought to control the long-term fate of soil carbon and nitrogen. It is known that such biogeochemical processes show disproportionally high reaction rates within nano- to micro-meter sized isolated zones ('hot spots') in comparison to surrounding areas. However, the majority of soil research is conducted on large bulk (> 1 g) samples, which are often significantly altered prior to analysis and analysed destructively. Thus it has previously been impossible to study elemental flows (e.g. C and N) between plants, microbes and soil in complex environments at the necessary spatial resolution within an intact soil system. By using nano-scale secondary ion mass spectrometry (NanoSIMS) in concert with other imaging techniques (e.g. scanning electron microscopy (SEM) and micro computed tomography (µCT)), classic analyses (isotopic and elemental analysis) and biochemical methods (e.g. GC-MS) it is possible to exhibit a more complete picture of soil processes at the micro-scale. I will present exemplarily results about the fate and distribution of organic C and N in complex micro-scale soil structures for a range of intact soil systems. Elemental imaging was used to study initial soil formation as an increase in the structural connectivity of micro-aggregates. Element distribution will be presented as a key to detect functional spatial patterns and biogeochemical hot spots in macro-aggregate functioning and development. In addition isotopic imaging will be demonstrated as a key to trace the fate of plant derived OM in the intact rhizosphere from the root to microbiota and mineral soil particles. Especially the use of stable isotope enrichment (e.g. 13CO2, 15NH4+) in conjunction with NanoSIMS allows to directly trace the fate of OM or nutrients in soils at the relevant scale (e.g. assimilate C / inorganic N in the rhizosphere). However, especially the elemental mapping requires more sophisticated computational approaches to evaluate (and quantify) the spatial heterogeneities of biogeochemical properties in intact soil systems.

The stability of DOTA-chelated radiopharmaceuticals within 225Ac decay pathway studied with density functional theory.

NASA Astrophysics Data System (ADS)

Karolak, Aleksandra; Khabibullin, Artem; Budzevich, Mikalai; Martinez, M.; Doliganski, Michael; McLaughlin, Mark; Woods, Lilia; Morse, David

Ligand structures encapsulating metal ions play a central role as contrast agents in Magnetic Resonance Imaging (MRI) or as agents delivering toxic cargo directly to tumor cells in targeted cancer therapy. The structural stability and interaction with solutions of such complexes are the key elements in understanding the foundation of delivery process. We present a comparative study for the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelated to radioactive isotopes of 225Ac, 221Fr, 217At, 213Bi and a control 68Gd. Using density functional theory methods we investigate the structural stability of complexes for cancer therapy including binding energies, charge transfer, electron densities. The van der Waals interactions are included in the simulations to take into account weak dispersion forces present in such structures. Our results reveal that Ac-DOTA, Bi-DOTA and Gd-DOTA are the most stable complexes in the group. We also show that the water environment is a key ingredient for the structural coordination of the DOTA structures. Support from the US Department of Energy under Grant No. DE-FG02-06ER46297 is acknowledged.

Milestone Completion Report WBS 1.3.5.05 ECP/VTK-m FY17Q4 [MS-17/03-06] Key Reduce / Spatial Division / Basic Advect / Normals STDA05-4.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreland, Kenneth D.

The FY17Q4 milestone of the ECP/VTK-m project includes the completion of a key-reduce scheduling mechanism, a spatial division algorithm, an algorithm for basic particle advection, and the computation of smoothed surface normals. With the completion of this milestone, we are able to, respectively, more easily group like elements (a common visualization algorithm operation), provide the fundamentals for geometric search structures, provide the fundamentals for many flow visualization algorithms, and provide more realistic rendering of surfaces approximated with facets.

Conversion and matched filter approximations for serial minimum-shift keyed modulation

NASA Technical Reports Server (NTRS)

Ziemer, R. E.; Ryan, C. R.; Stilwell, J. H.

1982-01-01

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase- and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of .000001.

SDMS: A scientific data management system

NASA Technical Reports Server (NTRS)

Massena, W. A.

1978-01-01

SDMS is a data base management system developed specifically to support scientific programming applications. It consists of a data definition program to define the forms of data bases, and FORTRAN-compatible subroutine calls to create and access data within them. Each SDMS data base contains one or more data sets. A data set has the form of a relation. Each column of a data set is defined to be either a key or data element. Key elements must be scalar. Data elements may also be vectors or matrices. The data elements in each row of the relation form an element set. SDMS permits direct storage and retrieval of an element set by specifying the corresponding key element values. To support the scientific environment, SDMS allows the dynamic creation of data bases via subroutine calls. It also allows intermediate or scratch data to be stored in temporary data bases which vanish at job end.

The Interiors of Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Helled, Ravit

2018-05-01

Probing the interiors of the giant planets in our Solar System is not an easy task. This requires a set of observations combined with theoretical models that are used to infer the planetary composition and its depth dependence. The masses of Jupiter and Saturn are 318 and 96 Earth masses, respectively, and since a few decades, we know that they mostly consist of hydrogen and helium. It is the mass of heavy elements (all elements heavier than helium) that is not well determined, as well as its distribution within the planets. While the heavy elements are not the dominating materials in Jupiter and Saturn, they are the key for our understanding of their formation and evolution histories. The planetary internal structure is inferred to fit the available observational constraints including the planetary masses, radii, 1-bar temperatures, rotation rates, and gravitational fields. Then, using theoretical equations of states (EOSs) for hydrogen, helium, their mixtures, and heavier elements (typically rocks and/or ices), a structure model is developed. However, there is no unique solution for the planetary structure, and the results depend on the used EOSs and the model assumptions imposed by the modeler. Standard interior models of Jupiter and Saturn include three main regions: (1) the central region (core) that consists of heavy elements, (2) an inner metallic hydrogen envelope that is helium rich, and (3) an outer molecular hydrogen envelope depleted with helium. The distribution of heavy elements can be either homogenous or discontinuous between the two envelopes. Major model assumptions that can affect the derived internal structure include the number of layers, the heat transport mechanism within the planet (and its entropy), the nature of the core (compact vs. diluted), and the location/pressure where the envelopes are divided. Alternative structure models assume a less distinct division between the layers and/or a less non-homogenous distribution of the heavy elements. The fact that the behavior of hydrogen at high pressures and temperatures in not perfectly known, and that helium separates from hydrogen at the deep interior add sources of uncertainties to the interior model. Today, with accurate measurements of the gravitational fields of Jupiter and Saturn from the Juno and Cassini missions, structure models can be further constrained. At the same time, these measurements introduce new challenges and open question for planetary modelers.

The BioImage Database Project: organizing multidimensional biological images in an object-relational database.

PubMed

Carazo, J M; Stelzer, E H

1999-01-01

The BioImage Database Project collects and structures multidimensional data sets recorded by various microscopic techniques relevant to modern life sciences. It provides, as precisely as possible, the circumstances in which the sample was prepared and the data were recorded. It grants access to the actual data and maintains links between related data sets. In order to promote the interdisciplinary approach of modern science, it offers a large set of key words, which covers essentially all aspects of microscopy. Nonspecialists can, therefore, access and retrieve significant information recorded and submitted by specialists in other areas. A key issue of the undertaking is to exploit the available technology and to provide a well-defined yet flexible structure for dealing with data. Its pivotal element is, therefore, a modern object relational database that structures the metadata and ameliorates the provision of a complete service. The BioImage database can be accessed through the Internet. Copyright 1999 Academic Press.

Ordered versus Unordered Map for Primitive Data Types

DTIC Science & Technology

2015-09-01

mapped to some element. C++ provides two types of map containers within the standard template library, the std ::map and the std ::unordered_map...classes. As the name implies, the containers main functional difference is that the elements in the std ::map are ordered by the key, and the std ...unordered_map are not ordered based on their key. The std ::unordered_map elements are placed into “buckets” based on a hash value computed for their key

Hyperspectral imaging-based credit card verifier structure with adaptive learning.

PubMed

Sumriddetchkajorn, Sarun; Intaravanne, Yuttana

2008-12-10

We propose and experimentally demonstrate a hyperspectral imaging-based optical structure for verifying a credit card. Our key idea comes from the fact that the fine detail of the embossed hologram stamped on the credit card is hard to duplicate, and therefore its key color features can be used for distinguishing between the real and counterfeit ones. As the embossed hologram is a diffractive optical element, we shine a number of broadband light sources one at a time, each at a different incident angle, on the embossed hologram of the credit card in such a way that different color spectra per incident angle beam are diffracted and separated in space. In this way, the center of mass of the histogram on each color plane is investigated by using a feed-forward backpropagation neural-network configuration. Our experimental demonstration using two off-the-shelf broadband white light emitting diodes, one digital camera, and a three-layer neural network can effectively identify 38 genuine and 109 counterfeit credit cards with false rejection rates of 5.26% and 0.92%, respectively. Key features include low cost, simplicity, no moving parts, no need of an additional decoding key, and adaptive learning.

Shifting the Curve: Fostering Academic Success in a Diverse Student Body.

PubMed

Elks, Martha L; Herbert-Carter, Janice; Smith, Marjorie; Klement, Brenda; Knight, Brandi Brandon; Anachebe, Ngozi F

2018-01-01

Diversity in the health care workforce is key to achieving health equity. Although U.S. medical schools have worked to increase the matriculation and academic success of underrepresented minority (URM) students (African Americans, Latinos, others), they have had only limited success. Lower standardized test scores, including on the Medical College Admission Test (MCAT), have been a barrier to matriculation for many URM applicants. Lower subsequent standardized exam scores, including on the United States Medical Licensing Exam Step 1, also have been an impediment to students' progress, with mean scores for URM students lagging behind those for others. Faculty at the Morehouse School of Medicine developed and implemented interventions to enhance the academic success of their URM students (about 75% are African American, and 5% are from other URM groups). To assess the outcomes of this work, the authors analyzed the MCAT scores and subsequent Step 1 scores of students in the graduating classes of 2009-2014. They also reviewed course evaluations, Graduation Questionnaires, and student and faculty interviews and focus groups. Students' Step 1 scores exceeded those expected based on their MCAT scores. This success was due to three key elements: (1) milieu and mentoring, (2) structure and content of the curriculum, and (3) monitoring. A series of mixed-method studies are planned to better discern the core elements of faculty-student relationships that are key to students' success. Lower test scores are not a fixed attribute; with the elements described, success is attainable for all students.

[Numerical modeling of shape memory alloy vascular stent's self-expandable progress and "optimized grid" of stent].

PubMed

Xu, Qiang; Liu, Yulan; Wang, Biao; He, Jin

2008-10-01

Vascular stent is an important medical appliance for angiocardiopathy. Its key deformation process is the expandable progress of stent in the vessel. The important deformation behaviour corresponds to two mechanics targets: deformation and stress. This paper is devoted to the research and development of vascular stent with proprietary intellectual property rights. The design of NiTinol self-expandable stent is optimized by means of finite element software. ANSYS is used to build the finite element simulation model of vascular stent; the molding material is NiTinol shape memory alloy. To cope with the factors that affect the structure of stent, the shape of grid and so on, the self-expanding process of Nitinol stent is simulated through computer. By making a comparison between two kinds of stents with similar grid structure, we present a new concept of "Optimized Grid" of stent.

The Shock and Vibration Digest. Volume 16, Number 9

DTIC Science & Technology

1984-09-01

behavior of the interface between dry Ottawa sand and concrete has been studied using a new device developed for Key Words: Underground structures, Concretes...Establishment, Ottawa , On- Reviews tario, Canada. Rept. No. NAE-AN-7, NRC-21276, -- 153 pp (Apr 1983) _ Recently developed analytical models for the...elements. The final phase of validation included simu- ,- 0 National Aeronautical Establishment, Ottawa , On- lation of dynamic tests of production

Revised U.S. Climate Science Plan Still Lacking in Key Areas

NASA Astrophysics Data System (ADS)

Showstack, Randy

2004-03-01

A U.S. National Research Council committee has found that a revised strategic plan for the U.S. Climate Change Science Program (CCSP) includes elements ``that could permit it to effectively guide research on climate and associated global changes over the next decades.'' However, the committee noted that the revision, issued by the CCSP, faces major hurdles related to funding, program priorities, management structure, and maintaining political independence.

Disability management in a sample of Australian self-insured companies.

PubMed

Westmorland, M; Buys, N; Clements, N

2002-09-20

Disability management (DM) is a term developed in North America and refers to the prevention and management of injury and illness in the workplace. The purpose of this paper is to report findings of an Australian study that examined whether self-insured employers in that country have implemented integrated DM programmes. Key principles underpinning such programmes are explored to identify the extent to which Australian employers have adopted them. Data was collected from 29 self-insured Australian companies in three Australian States using a structured interview format with additional open-ended questions. It was found that companies have in place, to varying degrees, some of the key elements of disability management programmes. However, these elements were often not well integrated in a comprehensive disability management approach. The focus on workplace-based, early intervention in the area of return to work for injured employees was particularly strong, but there was little evidence of formal labour-management committee structures responsible for implementing DM programmes. If the concept of DM is relevant to the Australian environment then this study would suggest that self-insured companies need to undertake further work to develop integrated approaches to preventing and managing disability in the workplace. Several limitations of this study are highlighted and it is concluded that further work in this area is needed.

Molecular modeling study for interaction between Bacillus subtilis Obg and Nucleotides.

PubMed

Lee, Yuno; Bang, Woo Young; Kim, Songmi; Lazar, Prettina; Kim, Chul Wook; Bahk, Jeong Dong; Lee, Keun Woo

2010-09-07

The bacterial Obg proteins (Spo0B-associated GTP-binding protein) belong to the subfamily of P-loop GTPase proteins that contain two equally and highly conserved domains, a C-terminal GTP binding domain and an N-terminal glycine-rich domain which is referred as the "Obg fold" and now it is considered as one of the new targets for antibacterial drug. When the Obg protein is associated with GTP, it becomes activated, because conformation of Obg fold changes due to the structural changes of GTPase switch elements in GTP binding site. In order to investigate the effects and structural changes in GTP bound to Obg and GTPase switch elements for activation, four different molecular dynamics (MD) simulations were performed with/without the three different nucleotides (GTP, GDP, and GDP + Pi) using the Bacillus subtilis Obg (BsObg) structure. The protein structures generated from the four different systems were compared using their representative structures. The pattern of C(alpha)-C(alpha) distance plot and angle between the two Obg fold domains of simulated apo form and each system (GTP, GDP, and GDP+Pi) were significantly different in the GTP-bound system from the others. The switch 2 element was significantly changed in GTP-bound system. Also root-mean-square fluctuation (RMSF) analysis revealed that the flexibility of the switch 2 element region was much higher than the others. This was caused by the characteristic binding mode of the nucleotides. When GTP was bound to Obg, its gamma-phosphate oxygen was found to interact with the key residue (D212) of the switch 2 element, on the contrary there was no such interaction found in other systems. Based on the results, we were able to predict the possible binding conformation of the activated form of Obg with L13, which is essential for the assembly with ribosome.

Transcendental Political Systems and the Gravity Model

NASA Technical Reports Server (NTRS)

Lock, Connor

2012-01-01

This summer I have been working on an Army Deep Futures Model project named Themis. Themis is a JPL based modeling framework that anticipates possible future states for the world within the next 25 years. The goal of this framework is to determine the likelihood that the US Army will need to intervene on behalf of the US strategic interests. Key elements that are modeled within this tool include the world structure and major decisions that are made by key actors. Each actor makes decisions based on their goals and within the constraints of the structure of the system in which they are located. In my research I have focused primarily on the effects of structures upon the decision-making processes of the actors within them. This research is a natural extension of my major program at Georgetown University, where I am studying the International Political Economy and the structures that make it up. My basic goal for this summer project was to be a helpful asset to the Themis modeling team, with any research done or processes learned constituting a bonus.

A finite element formulation preserving symmetric and banded diffusion stiffness matrix characteristics for fractional differential equations

NASA Astrophysics Data System (ADS)

Lin, Zeng; Wang, Dongdong

2017-10-01

Due to the nonlocal property of the fractional derivative, the finite element analysis of fractional diffusion equation often leads to a dense and non-symmetric stiffness matrix, in contrast to the conventional finite element formulation with a particularly desirable symmetric and banded stiffness matrix structure for the typical diffusion equation. This work first proposes a finite element formulation that preserves the symmetry and banded stiffness matrix characteristics for the fractional diffusion equation. The key point of the proposed formulation is the symmetric weak form construction through introducing a fractional weight function. It turns out that the stiffness part of the present formulation is identical to its counterpart of the finite element method for the conventional diffusion equation and thus the stiffness matrix formulation becomes trivial. Meanwhile, the fractional derivative effect in the discrete formulation is completely transferred to the force vector, which is obviously much easier and efficient to compute than the dense fractional derivative stiffness matrix. Subsequently, it is further shown that for the general fractional advection-diffusion-reaction equation, the symmetric and banded structure can also be maintained for the diffusion stiffness matrix, although the total stiffness matrix is not symmetric in this case. More importantly, it is demonstrated that under certain conditions this symmetric diffusion stiffness matrix formulation is capable of producing very favorable numerical solutions in comparison with the conventional non-symmetric diffusion stiffness matrix finite element formulation. The effectiveness of the proposed methodology is illustrated through a series of numerical examples.

A Flexible Socioeconomic Scenarios Framework for the Study of Plausible Arctic Futures

NASA Astrophysics Data System (ADS)

Reissell, A. K.; Peters, G. P.; Riahi, K.; Kroglund, M.; Lovecraft, A. L.; Nilsson, A. E.; Preston, B. L.; van Ruijven, B. J.

2016-12-01

Future developments of the Arctic region are associated with different drivers of change - climate, environmental, and socio-economic - and their interactions, and are highly uncertain. The uncertainty poses challenges for decision-making, calling for development of new analytical frameworks. Scenarios - coherent narratives describing potential futures, pathways to futures, and drivers of change along the way - can be used to explore the consequences of the key uncertainties, particularly in the long-term. In a participatory scenarios workshop, we used both top-down and bottom-up approaches for the development of a flexible socioeconomic scenarios framework. The top-down approach was linked to the global Integrated Assessment Modeling framework and its Shared Socio-Economic Pathways (SSPs), developing an Arctic extension of the set of five storylines on the main socioeconomic uncertainties in global climate change research. The bottom-up approach included participatory development of narratives originating from within the Arctic region. For extension of global SSPs to the regional level, we compared the key elements in the global SSPs (Population, Human Development, Economy & Lifestyle, Policies & Institutions, Technology, and Environment & Natural Resources) and key elements in the Arctic. Additional key elements for the Arctic scenarios include, for example, seasonal migration, the large role of traditional knowledge and culture, mixed economy, nested governance structure, human and environmental security, quality of infrastructure. The bottom-up derived results suggested that the scenarios developed independent of the SSPs could be mapped back to the SSPs to demonstrate consistency with respect to representing similar boundary conditions. The two approaches are complimentary, as the top-down approach can be used to set the global socio-economic and climate boundary conditions, and the bottom-up approach providing the regional context. One key uncertainty and driving force is the demand for resources (global or regional) that was mapped against the role of governance as well as adaptive and transformative capacity among actors within the Arctic. Resources demand has significant influence on the society, culture, economy and environment of the Arctic.

Design and analysis of photonic optical switches with improved wavelength selectivity

NASA Astrophysics Data System (ADS)

Wielichowski, Marcin; Patela, Sergiusz

2005-09-01

Efficient optical modulators and switches are the key elements of the future all-optical fiber networks. Aside from numerous advantages, the integrated optical devices suffer from excessive longitudinal dimensions. The dimensions may be significantly reduced with help of periodic structures, such as Bragg gratings, arrayed waveguides or multilayer structures. In this paper we describe methods of analysis and example of analytical results of a photonic switch with properties modified by the application of periodic change of effective refractive index. The switch is composed of a strip-waveguide directional coupler and a transversal Bragg grating.

Is it worth changing pattern recognition methods for structural health monitoring?

NASA Astrophysics Data System (ADS)

Bull, L. A.; Worden, K.; Cross, E. J.; Dervilis, N.

2017-05-01

The key element of this work is to demonstrate alternative strategies for using pattern recognition algorithms whilst investigating structural health monitoring. This paper looks to determine if it makes any difference in choosing from a range of established classification techniques: from decision trees and support vector machines, to Gaussian processes. Classification algorithms are tested on adjustable synthetic data to establish performance metrics, then all techniques are applied to real SHM data. To aid the selection of training data, an informative chain of artificial intelligence tools is used to explore an active learning interaction between meaningful clusters of data.

A lightweight vibro-acoustic metamaterial demonstrator: Numerical and experimental investigation

NASA Astrophysics Data System (ADS)

Claeys, C.; Deckers, E.; Pluymers, B.; Desmet, W.

2016-03-01

In recent years metamaterials gained a lot of attention due to their superior noise and vibration insulation properties, be it at least in some targeted and tuneable frequency ranges, referred to as stopbands. These are frequency zones for which free wave propagation is prevented throughout the metamaterial, resulting in frequency zones of pronounced wave attenuation. Metamaterials are achieved due to addition of an, often periodic, grid of resonant structures to a host material or structure. The interaction between resonant inclusions and host structure can lead to a performance which is superior to the ones of any of the constituent materials. A key element in this concept is that waves can be affected by incorporating structural resonant elements of sub-wavelength sizes, i.e. features that are actually smaller than the wavelength of the waves to be affected. This paves the way towards compact and light vibro-acoustic solutions in the lower frequency ranges. This paper discusses the numerical design and experimental validation of acoustic insulation based on the concept of metamaterials: a hollow core periodic sandwich structure with added local resonant structures. In order to investigate the sensitivity to specific parameters in the metamaterial design and the robustness of the design, a set of variations on the nominal design are investigated. The stop bands are numerically predicted through unit cell modelling after which a full vibro-acoustic finite element model is applied to predict the insertion loss of the demonstrator. The results of these analyses are compared with measurements; both indicate that this metamaterials concept can be applied to combine light weight, compact volume and good acoustic behaviour.

E-cadherin junction formation involves an active kinetic nucleation process

PubMed Central

Biswas, Kabir H.; Hartman, Kevin L.; Yu, Cheng-han; Harrison, Oliver J.; Song, Hang; Smith, Adam W.; Huang, William Y. C.; Lin, Wan-Chen; Guo, Zhenhuan; Padmanabhan, Anup; Troyanovsky, Sergey M.; Dustin, Michael L.; Shapiro, Lawrence; Honig, Barry; Zaidel-Bar, Ronen; Groves, Jay T.

2015-01-01

Epithelial (E)-cadherin-mediated cell−cell junctions play important roles in the development and maintenance of tissue structure in multicellular organisms. E-cadherin adhesion is thus a key element of the cellular microenvironment that provides both mechanical and biochemical signaling inputs. Here, we report in vitro reconstitution of junction-like structures between native E-cadherin in living cells and the extracellular domain of E-cadherin (E-cad-ECD) in a supported membrane. Junction formation in this hybrid live cell-supported membrane configuration requires both active processes within the living cell and a supported membrane with low E-cad-ECD mobility. The hybrid junctions recruit α-catenin and exhibit remodeled cortical actin. Observations suggest that the initial stages of junction formation in this hybrid system depend on the trans but not the cis interactions between E-cadherin molecules, and proceed via a nucleation process in which protrusion and retraction of filopodia play a key role. PMID:26290581

E-cadherin junction formation involves an active kinetic nucleation process

DOE PAGES

Biswas, Kabir H.; Hartman, Kevin L.; Yu, Cheng -han; ...

2015-08-19

Epithelial (E)-cadherin-mediated cell–cell junctions play important roles in the development and maintenance of tissue structure in multicellular organisms. E-cadherin adhesion is thus a key element of the cellular microenvironment that provides both mechanical and biochemical signaling inputs. Here, we report in vitro reconstitution of junction-like structures between native E-cadherin in living cells and the extracellular domain of E-cadherin in a supported membrane. Junction formation in this hybrid live cell-supported membrane configuration requires both active processes within the living cell and a supported membrane with low E-cad-ECD mobility. The hybrid junctions recruit α-catenin and exhibit remodeled cortical actin. Observations suggest thatmore » the initial stages of junction formation in this hybrid system depend on the trans but not the cis interactions between E-cadherin molecules, and proceed via a nucleation process in which protrusion and retraction of filopodia play a key role.« less

E-cadherin junction formation involves an active kinetic nucleation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, Kabir H.; Hartman, Kevin L.; Yu, Cheng -han

Epithelial (E)-cadherin-mediated cell–cell junctions play important roles in the development and maintenance of tissue structure in multicellular organisms. E-cadherin adhesion is thus a key element of the cellular microenvironment that provides both mechanical and biochemical signaling inputs. Here, we report in vitro reconstitution of junction-like structures between native E-cadherin in living cells and the extracellular domain of E-cadherin in a supported membrane. Junction formation in this hybrid live cell-supported membrane configuration requires both active processes within the living cell and a supported membrane with low E-cad-ECD mobility. The hybrid junctions recruit α-catenin and exhibit remodeled cortical actin. Observations suggest thatmore » the initial stages of junction formation in this hybrid system depend on the trans but not the cis interactions between E-cadherin molecules, and proceed via a nucleation process in which protrusion and retraction of filopodia play a key role.« less

A framework to support human factors of automation in railway intelligent infrastructure.

PubMed

Dadashi, Nastaran; Wilson, John R; Golightly, David; Sharples, Sarah

2014-01-01

Technological and organisational advances have increased the potential for remote access and proactive monitoring of the infrastructure in various domains and sectors - water and sewage, oil and gas and transport. Intelligent Infrastructure (II) is an architecture that potentially enables the generation of timely and relevant information about the state of any type of infrastructure asset, providing a basis for reliable decision-making. This paper reports an exploratory study to understand the concepts and human factors associated with II in the railway, largely drawing from structured interviews with key industry decision-makers and attachment to pilot projects. Outputs from the study include a data-processing framework defining the key human factors at different levels of the data structure within a railway II system and a system-level representation. The framework and other study findings will form a basis for human factors contributions to systems design elements such as information interfaces and role specifications.

Mining for recurrent long-range interactions in RNA structures reveals embedded hierarchies in network families.

PubMed

Reinharz, Vladimir; Soulé, Antoine; Westhof, Eric; Waldispühl, Jérôme; Denise, Alain

2018-05-04

The wealth of the combinatorics of nucleotide base pairs enables RNA molecules to assemble into sophisticated interaction networks, which are used to create complex 3D substructures. These interaction networks are essential to shape the 3D architecture of the molecule, and also to provide the key elements to carry molecular functions such as protein or ligand binding. They are made of organised sets of long-range tertiary interactions which connect distinct secondary structure elements in 3D structures. Here, we present a de novo data-driven approach to extract automatically from large data sets of full RNA 3D structures the recurrent interaction networks (RINs). Our methodology enables us for the first time to detect the interaction networks connecting distinct components of the RNA structure, highlighting their diversity and conservation through non-related functional RNAs. We use a graphical model to perform pairwise comparisons of all RNA structures available and to extract RINs and modules. Our analysis yields a complete catalog of RNA 3D structures available in the Protein Data Bank and reveals the intricate hierarchical organization of the RNA interaction networks and modules. We assembled our results in an online database (http://carnaval.lri.fr) which will be regularly updated. Within the site, a tool allows users with a novel RNA structure to detect automatically whether the novel structure contains previously observed RINs.

A nickel metal hydride battery for electric vehicles

NASA Astrophysics Data System (ADS)

Ovshinsky, S. R.; Fetcenko, M. A.; Ross, J.

1993-04-01

An efficient battery is the key technological element to the development of practical electric vehicles. The science and technology of a nickel metal hydride battery, which stores hydrogen in the solid hydride phase and has high energy density, high power, long life, tolerance to abuse, a wide range of operating temperature, quick-charge capability, and totally sealed maintenance-free operation, is described. A broad range of multi-element metal hydride materials that use structural and compositional disorder on several scales of length has been engineered for use as the negative electrode in this battery. The battery operates at ambient temperature, is made of nontoxic materials, and is recyclable. Demonstration of the manufacturing technology has been achieved.

Crystal structures reveal metal-binding plasticity at the metallo-β-lactamase active site of PqqB from Pseudomonas putida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, Xiongying; Latham, John A.; Klema, Valerie J.

PqqB is an enzyme involved in the biosynthesis of pyrroloquinoline quinone and a distal member of the metallo-β-lactamase (MBL) superfamily. PqqB lacks two residues in the conserved signature motif HxHxDH that makes up the key metal-chelating elements that can bind up to two metal ions at the active site of MBLs and other members of its superfamily. Here, we report crystal structures of PqqB bound to Mn2+, Mg2+, Cu2+, and Zn2+. These structures demonstrate that PqqB can still bind metal ions at the canonical MBL active site. The fact that PqqB can adapt its side chains to chelate a widemore » spectrum of metal ions with different coordination features on a uniform main chain scaffold demonstrates its metal-binding plasticity. This plasticity may provide insights into the structural basis of promiscuous activities found in ensembles of metal complexes within this superfamily. Furthermore, PqqB belongs to a small subclass of MBLs that contain an additional CxCxxC motif that binds a structural Zn2+. Our data support a key role for this motif in dimerization.« less

Post-Buckling and Ultimate Strength Analysis of Stiffened Composite Panel Base on Progressive Damage

NASA Astrophysics Data System (ADS)

Zhang, Guofan; Sun, Xiasheng; Sun, Zhonglei

Stiffened composite panel is the typical thin wall structure applied in aerospace industry, and its main failure mode is buckling subjected to compressive loading. In this paper, the development of an analysis approach using Finite Element Method on post-buckling behavior of stiffened composite structures under compression was presented. Then, the numerical results of stiffened panel are obtained by FE simulations. A thorough comparison were accomplished by comparing the load carrying capacity and key position strains of the specimen with test. The comparison indicates that the FEM results which adopted developed methodology could meet the demand of engineering application in predicting the post-buckling behavior of intact stiffened structures in aircraft design stage.

Nonlinear layered lattice model and generalized solitary waves in imperfectly bonded structures.

PubMed

Khusnutdinova, Karima R; Samsonov, Alexander M; Zakharov, Alexey S

2009-05-01

We study nonlinear waves in a two-layered imperfectly bonded structure using a nonlinear lattice model. The key element of the model is an anharmonic chain of oscillating dipoles, which can be viewed as a basic lattice analog of a one-dimensional macroscopic waveguide. Long nonlinear longitudinal waves in a layered lattice with a soft middle (or bonding) layer are governed by a system of coupled Boussinesq-type equations. For this system we find conservation laws and show that pure solitary waves, which exist in a single equation and can exist in the coupled system in the symmetric case, are structurally unstable and are replaced with generalized solitary waves.

Dynamic loading and stress life analysis of permanent space station modules

NASA Astrophysics Data System (ADS)

Anisimov, A. V.; Krokhin, I. A.; Likhoded, A. I.; Malinin, A. A.; Panichkin, N. G.; Sidorov, V. V.; Titov, V. A.

2016-11-01

Some methodological approaches to solving several key problems of dynamic loading and structural strength analysis of Permanent Space Station (PSS)modules developed on the basis of the working experience of Soviet and Russian PSS and the International Space station (ISS) are presented. The solutions of the direct and semi-inverse problems of PSS structure dynamics are mathematically stated. Special attention is paid to the use of the results of ground structural strength tests of space station modules and the data on the actual flight actions on the station and its dynamic responses in the orbital operation regime. The procedure of determining the dynamics and operation life parameters of elements of the PSS modules is described.

Development of a structured observational method for the systematic assessment of school food-choice architecture.

PubMed

Ozturk, Orgul D; McInnes, Melayne M; Blake, Christine E; Frongillo, Edward A; Jones, Sonya J

2016-01-01

The objective of this study is to develop a structured observational method for the systematic assessment of the food-choice architecture that can be used to identify key points for behavioral economic intervention intended to improve the health quality of children's diets. We use an ethnographic approach with observations at twelve elementary schools to construct our survey instrument. Elements of the structured observational method include decision environment, salience, accessibility/convenience, defaults/verbal prompts, number of choices, serving ware/method/packaging, and social/physical eating environment. Our survey reveals important "nudgeable" components of the elementary school food-choice architecture, including precommitment and default options on the lunch line.

Building HVAC control knowledge data schema – Towards a unified representation of control system knowledge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yan; Treado, Stephen J.; Messner, John I.

Building control systems for Heating, Ventilation, and Air Conditioning (HVAC) play a key role in realizing the functionality and operation of building systems and components. Building Control Knowledge (BCK) is the logic and algorithms embedded throughout building control system. There are different methods to represent the BCK. These methods differ in the selection of BCK representing elements and the format of those elements. There is a lack of standard data schema, for storing, retrieving, and reusing structured BCK. In this study, a modular data schema is created for BCK representation. The data schema contains eleven representing elements, i.e., control modulemore » name, operation mode, system schematic, control flow diagram, data point, alarm, parameter, control sequence, function, and programming code. Each element is defined with specific attributes. This data schema is evaluated through a case study demonstration. The demonstration shows a new way to represent the BCK with standard formats.« less

NASA policy on pricing shuttle launch services

NASA Technical Reports Server (NTRS)

Smith, J. M.

1977-01-01

The paper explains the rationale behind key elements of the pricing policy for STS, the major features of the non-government user policy, and some of the stimulating features of the policy which will open space to a wide range of new users. Attention is given to such major policy features as payment schedule, cost and standard services, the two phase pricing structure, optional services, shared flights, cancellation and postponement, and earnest money.

Global-local methodologies and their application to nonlinear analysis

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.

1989-01-01

An assessment is made of the potential of different global-local analysis strategies for predicting the nonlinear and postbuckling responses of structures. Two postbuckling problems of composite panels are used as benchmarks and the application of different global-local methodologies to these benchmarks is outlined. The key elements of each of the global-local strategies are discussed and future research areas needed to realize the full potential of global-local methodologies are identified.

Spacelab shaping space operations planning

NASA Technical Reports Server (NTRS)

Steven, F. R.; Reinhold, C.

1976-01-01

An up-to-date picture is presented of the organizational structure, the key management personnel, and management relationships of the Spacelab program. Attention is also given to Spacelab's development status and plans for its operations. A number of charts are provided to illustrate the organizational relations. It is pointed out that the parties involved in Spacelab activities must yet resolve questions about ownership of transportation-system elements, payloads, ground support facilities, and data obtained from space missions.

Stabilizing the boat conformation of cyclohexane rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dasgupta, S.; Goddard, W.A. III; Moldowan, J.M.

1995-06-21

In calculating the energetics for various conformers of the A, B, and C series of hopanoid hydrocarbons present in mature oil reservoirs, we find that the B series prefers the boat conformation (by 1.3-2.5 kcal/mol) for the D cyclohexane ring. We analyze the structural elements responsible for stabilizing this boat conformation, identify the key features, and illustrate how one might stabilize boat conformations of other systems. 5 refs., 3 figs., 2 tabs.

Computational methods for constructing protein structure models from 3D electron microscopy maps.

PubMed

Esquivel-Rodríguez, Juan; Kihara, Daisuke

2013-10-01

Protein structure determination by cryo-electron microscopy (EM) has made significant progress in the past decades. Resolutions of EM maps have been improving as evidenced by recently reported structures that are solved at high resolutions close to 3Å. Computational methods play a key role in interpreting EM data. Among many computational procedures applied to an EM map to obtain protein structure information, in this article we focus on reviewing computational methods that model protein three-dimensional (3D) structures from a 3D EM density map that is constructed from two-dimensional (2D) maps. The computational methods we discuss range from de novo methods, which identify structural elements in an EM map, to structure fitting methods, where known high resolution structures are fit into a low-resolution EM map. A list of available computational tools is also provided. Copyright © 2013 Elsevier Inc. All rights reserved.

An alternative to Guyan reduction of finite-element models

NASA Technical Reports Server (NTRS)

Lin, Jiguan Gene

1988-01-01

Structural modeling is a key part of structural system identification for large space structures. Finite-element structural models are commonly used in practice because of their general applicability and availability. The initial models generated by using a standard computer program such as NASTRAN, ANSYS, SUPERB, STARDYNE, STRUDL, etc., generally contain tens of thousands of degrees of freedom. The models must be reduced for purposes of identification. Not only does the magnitude of the identification effort grow exponentially as a function of the number of degrees of freedom, but numerical procedures may also break down because of accumulated round-off errors. Guyan reduction is usually applied after a static condensation. Misapplication of Guyan reduction can lead to serious modeling errors. It is quite unfortunate and disappointing, since the accuracy of the original detailed finite-element model one tries very hard to achieve is lost by the reduction. First, why and how Guyan reduction always causes loss of accuracy is examined. An alternative approach is then introduced. The alternative can be thought of as an improvement of Guyan reduction, the Rayleigh-Ritz method, and in particular the recent algorithm of Wilson, Yuan, and Dickens. Unlike Guyan reduction, the use of the alternative does not need any special insight, experience, or skill for partitioning the structural degrees of freedom. In addition to model condensation, this alternative approach can also be used for predicting analytically, quickly, and economically, what are those structural modes that are excitable by a force actuator at a given trial location. That is, in the excitation of the structural modes for identification, it can be used for guiding the placement of the force actuators.

A New Secondary Structure Assignment Algorithm Using Cα Backbone Fragments

PubMed Central

Cao, Chen; Wang, Guishen; Liu, An; Xu, Shutan; Wang, Lincong; Zou, Shuxue

2016-01-01

The assignment of secondary structure elements in proteins is a key step in the analysis of their structures and functions. We have developed an algorithm, SACF (secondary structure assignment based on Cα fragments), for secondary structure element (SSE) assignment based on the alignment of Cα backbone fragments with central poses derived by clustering known SSE fragments. The assignment algorithm consists of three steps: First, the outlier fragments on known SSEs are detected. Next, the remaining fragments are clustered to obtain the central fragments for each cluster. Finally, the central fragments are used as a template to make assignments. Following a large-scale comparison of 11 secondary structure assignment methods, SACF, KAKSI and PROSS are found to have similar agreement with DSSP, while PCASSO agrees with DSSP best. SACF and PCASSO show preference to reducing residues in N and C cap regions, whereas KAKSI, P-SEA and SEGNO tend to add residues to the terminals when DSSP assignment is taken as standard. Moreover, our algorithm is able to assign subtle helices (310-helix, π-helix and left-handed helix) and make uniform assignments, as well as to detect rare SSEs in β-sheets or long helices as outlier fragments from other programs. The structural uniformity should be useful for protein structure classification and prediction, while outlier fragments underlie the structure–function relationship. PMID:26978354

Isolation, characterization and expression analysis of the BABY BOOM (BBM) gene from Larix kaempferi × L. olgensis during adventitious rooting.

PubMed

Li, Kui-Peng; Sun, Xiao-Mei; Han, Hua; Zhang, Shou-Gong

2014-11-10

The full-length cDNA and genomic sequences of the BABY BOOM (BBM) gene, designated LkBBM, were isolated from Larix kaempferi × Larix olgensis. The 3324 bp cDNA was cloned and its open reading frame (ORF) consists of 2370 nucleotides. The deduced 789 amino acid protein contains two AP2 domains and a BBM specific motif. Four conserved motifs between BBM and PLT were identified, which may be conducive to the similar function of BBM and PLT. The three dimensional (3D) structure of LkBBM was predicted and β-sheets in the AP2-R2 domain of LkBBM might recognize the specific base pairs in the major groove. Analysis of the LkBBM gene structure indicates that the gene has eight introns and nine exons. In the 5'-flanking promoter region of LkBBM, many important potential cis-acting elements were identified, such as the TATABOX5 element (a functional TATA element), ROOTMOTIFTAPOX1 element (element of root specificity), AUXREPSIAA4 element (element involved in auxin responsiveness and gene expression in root meristem), MYB1AT element (element involved in MYB recognition), ARR1AT element (element involved in cytokinin responsiveness), GARE1OSREP1 element (element involved in gibberellin responsiveness) and PYRIMIDINEBOXHVEPB1 element (element involved in abscisic acid responsiveness), which all suggested that the expression of LkBBM is highly regulated. Compared with gene expression levels in the stem, stem tip and leaf, LkBBM shows a specific expression in the root, which indicates that LkBBM plays a key role in regulating the development and growth of root in larch. In the processing of larch adventitious root formation, LkBBM started to express on the eighth day after rooting treatment and its transcript level increased continuously afterwards. According to the gene characteristics, LkBBM is proposed as a molecular marker for root primordia of larch, and the initial period of LkBBM expression may be the formation period of root primordia in the processing of adventitious rooting of larch. Copyright © 2014 Elsevier B.V. All rights reserved.

A conceptual framework to support exposure science research ...

EPA Pesticide Factsheets

While knowledge of exposure is fundamental to assessing and mitigating risks, exposure information has been costly and difficult to generate. Driven by major scientific advances in analytical methods, biomonitoring, computational tools, and a newly articulated vision for a greater impact in public health, the field of exposure science is undergoing a rapid transition that allows it to be more agile, predictive, and data- and knowledge-driven. A necessary element of this evolved paradigm is an organizational and predictive framework for exposure science that furthers the application of systems-based approaches. To enable such systems-based approaches, we proposed the Aggregate Exposure Pathway (AEP) concept to organize data and information emerging from an invigorated and expanding field of exposure science. The AEP framework is a layered structure that describes the elements of an exposure pathway, as well as the relationship between those elements. The basic building blocks of an AEP adopt the naming conventions used for Adverse Outcome Pathways (AOPs): Key Events (KEs) to describe the measurable, obligate steps through the AEP; and Key Event Relationships (KERs) describe the linkages between KEs. Importantly, the AEP offers an intuitive approach to organize exposure information from sources to internal site of action, setting the stage for predicting stressor concentrations at an internal target site. These predicted concentrations can help inform the r

Automatic definition of the oncologic EHR data elements from NCIT in OWL.

PubMed

Cuggia, Marc; Bourdé, Annabel; Turlin, Bruno; Vincendeau, Sebastien; Bertaud, Valerie; Bohec, Catherine; Duvauferrier, Régis

2011-01-01

Semantic interoperability based on ontologies allows systems to combine their information and process them automatically. The ability to extract meaningful fragments from ontology is a key for the ontology re-use and the construction of a subset will help to structure clinical data entries. The aim of this work is to provide a method for extracting a set of concepts for a specific domain, in order to help to define data elements of an oncologic EHR. a generic extraction algorithm was developed to extract, from the NCIT and for a specific disease (i.e. prostate neoplasm), all the concepts of interest into a sub-ontology. We compared all the concepts extracted to the concepts encoded manually contained into the multi-disciplinary meeting report form (MDMRF). We extracted two sub-ontologies: sub-ontology 1 by using a single key concept and sub-ontology 2 by using 5 additional keywords. The coverage of sub-ontology 2 to the MDMRF concepts was 51%. The low rate of coverage is due to the lack of definition or mis-classification of the NCIT concepts. By providing a subset of concepts focused on a particular domain, this extraction method helps at optimizing the binding process of data elements and at maintaining and enriching a domain ontology.

Optimization design and laser damage threshold analysis of pulse compression multilayer dielectric gratings

NASA Astrophysics Data System (ADS)

Fan, Shuwei; Bai, Liang; Chen, Nana

2016-08-01

As one of the key elements of high-power laser systems, the pulse compression multilayer dielectric grating is required for broader band, higher diffraction efficiency and higher damage threshold. In this paper, the multilayer dielectric film and the multilayer dielectric gratings(MDG) were designed by eigen matrix and optimized with the help of generic algorithm and rigorous coupled wave method. The reflectivity was close to 100% and the bandwith were over 250nm, twice compared to the unoptimized film structure. The simulation software of standing wave field distribution within MDG was developed and the electric field of the MDG was calculated. And the key parameters which affected the electric field distribution were also studied.

Fostering evidence-based quality improvement for patient-centered medical homes: Initiating local quality councils to transform primary care.

PubMed

Stockdale, Susan E; Zuchowski, Jessica; Rubenstein, Lisa V; Sapir, Negar; Yano, Elizabeth M; Altman, Lisa; Fickel, Jacqueline J; McDougall, Skye; Dresselhaus, Timothy; Hamilton, Alison B

Although the patient-centered medical home endorses quality improvement principles, methods for supporting ongoing, systematic primary care quality improvement have not been evaluated. We introduced primary care quality councils at six Veterans Health Administration sites as an organizational intervention with three key design elements: (a) fostering interdisciplinary quality improvement leadership, (b) establishing a structured quality improvement process, and (c) facilitating organizationally aligned frontline quality improvement innovation. Our evaluation objectives were to (a) assess design element implementation, (b) describe implementation barriers and facilitators, and (c) assess successful quality improvement project completion and spread. We analyzed administrative records and conducted interviews with 85 organizational leaders. We developed and applied criteria for assessing design element implementation using hybrid deductive/inductive analytic techniques. All quality councils implemented interdisciplinary leadership and a structured quality improvement process, and all but one completed at least one quality improvement project and a toolkit for spreading improvements. Quality councils were perceived as most effective when service line leaders had well-functioning interdisciplinary communication. Matching positions within leadership hierarchies with appropriate supportive roles facilitated frontline quality improvement efforts. Two key resources were (a) a dedicated internal facilitator with project management, data collection, and presentation skills and (b) support for preparing customized data reports for identifying and addressing practice level quality issues. Overall, quality councils successfully cultivated interdisciplinary, multilevel primary care quality improvement leadership with accountability mechanisms and generated frontline innovations suitable for spread. Practice level performance data and quality improvement project management support were critical. In order to successfully facilitate systematic, sustainable primary care quality improvement, regional and executive health care system leaders should engage interdisciplinary practice level leadership in a priority-setting process that encourages frontline innovation and establish local structures such as quality councils to coordinate quality improvement initiatives, ensure accountability, and promote spread of best practices.

Solution Binding and Structural Analyses Reveal Potential Multidrug Resistance Functions for SAV2435 and CTR107 and Other GyrI-like Proteins.

PubMed

Moreno, Andrew; Froehlig, John R; Bachas, Sharrol; Gunio, Drew; Alexander, Teressa; Vanya, Aaron; Wade, Herschel

2016-08-30

Multidrug resistance (MDR) refers to the acquired ability of cells to tolerate a broad range of toxic compounds. One mechanism cells employ is to increase the level of expression of efflux pumps for the expulsion of xenobiotics. A key feature uniting efflux-related mechanisms is multidrug (MD) recognition, either by efflux pumps themselves or by their transcriptional regulators. However, models describing MD binding by MDR effectors are incomplete, underscoring the importance of studies focused on the recognition elements and key motifs that dictate polyspecific binding. One such motif is the GyrI-like domain, which is found in several MDR proteins and is postulated to have been adapted for small-molecule binding and signaling. Here we report the solution binding properties and crystal structures of two proteins containing GyrI-like domains, SAV2435 and CTR107, bound to various ligands. Furthermore, we provide a comparison with deposited crystal structures of GyrI-like proteins, revealing key features of GyrI-like domains that not only support polyspecific binding but also are conserved among GyrI-like domains. Together, our studies suggest that GyrI-like domains perform evolutionarily conserved functions connected to multidrug binding and highlight the utility of these types of studies for elucidating mechanisms of MDR.

Road Network Extraction from Dsm by Mathematical Morphology and Reasoning

NASA Astrophysics Data System (ADS)

Li, Yan; Wu, Jianliang; Zhu, Lin; Tachibana, Kikuo

2016-06-01

The objective of this research is the automatic extraction of the road network in a scene of the urban area from a high resolution digital surface model (DSM). Automatic road extraction and modeling from remote sensed data has been studied for more than one decade. The methods vary greatly due to the differences of data types, regions, resolutions et al. An advanced automatic road network extraction scheme is proposed to address the issues of tedium steps on segmentation, recognition and grouping. It is on the basis of a geometric road model which describes a multiple-level structure. The 0-dimension element is intersection. The 1-dimension elements are central line and side. The 2-dimension element is plane, which is generated from the 1-dimension elements. The key feature of the presented approach is the cross validation for the three road elements which goes through the entire procedure of their extraction. The advantage of our model and method is that linear elements of the road can be derived directly, without any complex, non-robust connection hypothesis. An example of Japanese scene is presented to display the procedure and the performance of the approach.

Rebels with a cause: molecular features and physiological consequences of yeast prions.

PubMed

Garcia, David M; Jarosz, Daniel F

2014-02-01

Prions are proteins that convert between structurally and functionally distinct states, at least one of which is self-perpetuating. The prion fold templates the conversion of native protein, altering its structure and function, and thus serves as a protein-based element of inheritance. Molecular chaperones ensure that these prion aggregates are divided and faithfully passed from mother cells to their daughters. Prions were originally identified as the cause of several rare neurodegenerative diseases in mammals, but the last decade has brought great progress in understanding their broad importance in biology and evolution. Most prion proteins regulate information flow in signaling networks, or otherwise affect gene expression. Consequently, switching into and out of prion states creates diverse new traits – heritable changes based on protein structure rather than nucleic acid. Despite intense study of the molecular mechanisms of this paradigm-shifting, epigenetic mode of inheritance, many key questions remain. Recent studies in yeast that support the view that prions are common, often beneficial elements of inheritance that link environmental stress to the appearance of new traits.

Preparing Our Schools for the 21st Century. 1999 ASCD Yearbook.

ERIC Educational Resources Information Center

Marsh, David D., Ed.

This yearbook offers a view of the key elements of schooling in the 21st century, outlining the nature of the change process that will be needed to create such schools. These key elements are drawn from the experience of educational reform in several countries and reflect a growing consensus about which elements will help all schools achieve both…

RNA-dependent RNA polymerase of hepatitis C virus binds to its coding region RNA stem-loop structure, 5BSL3.2, and its negative strand.

PubMed

Kanamori, Hiroshi; Yuhashi, Kazuhito; Ohnishi, Shin; Koike, Kazuhiko; Kodama, Tatsuhiko

2010-05-01

The hepatitis C virus NS5B RNA-dependent RNA polymerase (RdRp) is a key enzyme involved in viral replication. Interaction between NS5B RdRp and the viral RNA sequence is likely to be an important step in viral RNA replication. The C-terminal half of the NS5B-coding sequence, which contains the important cis-acting replication element, has been identified as an NS5B-binding sequence. In the present study, we confirm the specific binding of NS5B to one of the RNA stem-loop structures in the region, 5BSL3.2. In addition, we show that NS5B binds to the complementary strand of 5BSL3.2 (5BSL3.2N). The bulge structure of 5BSL3.2N was shown to be indispensable for tight binding to NS5B. In vitro RdRp activity was inhibited by 5BSL3.2N, indicating the importance of the RNA element in the polymerization by RdRp. These results suggest the involvement of the RNA stem-loop structure of the negative strand in the replication process.

Improved magnetic encoding device and method for making the same. [Patent application

DOEpatents

Fox, R.J.

A magnetic encoding device and method for making the same are provided for use as magnetic storage media in identification control applications that give output signals from a reader that are of shorter duration and substantially greater magnitude than those of the prior art. Magnetic encoding elements are produced by uniformly bending wire or strip stock of a magnetic material longitudinally about a common radius to exceed the elastic limit of the material and subsequently mounting the material so that it is restrained in an unbent position on a substrate of nonmagnetic material. The elements are spot weld attached to a substrate to form a binary coded array of elements according to a desired binary code. The coded substrate may be enclosed in a plastic laminate structure. Such devices may be used for security badges, key cards, and the like and may have many other applications. 7 figures.

Method for making an improved magnetic encoding device

DOEpatents

Fox, Richard J.

1981-01-01

A magnetic encoding device and method for making the same are provided for use as magnetic storage mediums in identification control applications which give output signals from a reader that are of shorter duration and substantially greater magnitude than those of the prior art. Magnetic encoding elements are produced by uniformly bending wire or strip stock of a magnetic material longitudinally about a common radius to exceed the elastic limit of the material and subsequently mounting the material so that it is restrained in an unbent position on a substrate of nonmagnetic material. The elements are spot weld attached to a substrate to form a binary coded array of elements according to a desired binary code. The coded substrate may be enclosed in a plastic laminate structure. Such devices may be used for security badges, key cards, and the like and may have many other applications.

Monte Carlo simulation methodology for the reliabilty of aircraft structures under damage tolerance considerations

NASA Astrophysics Data System (ADS)

Rambalakos, Andreas

Current federal aviation regulations in the United States and around the world mandate the need for aircraft structures to meet damage tolerance requirements through out the service life. These requirements imply that the damaged aircraft structure must maintain adequate residual strength in order to sustain its integrity that is accomplished by a continuous inspection program. The multifold objective of this research is to develop a methodology based on a direct Monte Carlo simulation process and to assess the reliability of aircraft structures. Initially, the structure is modeled as a parallel system with active redundancy comprised of elements with uncorrelated (statistically independent) strengths and subjected to an equal load distribution. Closed form expressions for the system capacity cumulative distribution function (CDF) are developed by expanding the current expression for the capacity CDF of a parallel system comprised by three elements to a parallel system comprised with up to six elements. These newly developed expressions will be used to check the accuracy of the implementation of a Monte Carlo simulation algorithm to determine the probability of failure of a parallel system comprised of an arbitrary number of statistically independent elements. The second objective of this work is to compute the probability of failure of a fuselage skin lap joint under static load conditions through a Monte Carlo simulation scheme by utilizing the residual strength of the fasteners subjected to various initial load distributions and then subjected to a new unequal load distribution resulting from subsequent fastener sequential failures. The final and main objective of this thesis is to present a methodology for computing the resulting gradual deterioration of the reliability of an aircraft structural component by employing a direct Monte Carlo simulation approach. The uncertainties associated with the time to crack initiation, the probability of crack detection, the exponent in the crack propagation rate (Paris equation) and the yield strength of the elements are considered in the analytical model. The structural component is assumed to consist of a prescribed number of elements. This Monte Carlo simulation methodology is used to determine the required non-periodic inspections so that the reliability of the structural component will not fall below a prescribed minimum level. A sensitivity analysis is conducted to determine the effect of three key parameters on the specification of the non-periodic inspection intervals: namely a parameter associated with the time to crack initiation, the applied nominal stress fluctuation and the minimum acceptable reliability level.

A quantitative metric to identify critical elements within seafood supply networks.

PubMed

Plagányi, Éva E; van Putten, Ingrid; Thébaud, Olivier; Hobday, Alistair J; Innes, James; Lim-Camacho, Lilly; Norman-López, Ana; Bustamante, Rodrigo H; Farmery, Anna; Fleming, Aysha; Frusher, Stewart; Green, Bridget; Hoshino, Eriko; Jennings, Sarah; Pecl, Gretta; Pascoe, Sean; Schrobback, Peggy; Thomas, Linda

2014-01-01

A theoretical basis is required for comparing key features and critical elements in wild fisheries and aquaculture supply chains under a changing climate. Here we develop a new quantitative metric that is analogous to indices used to analyse food-webs and identify key species. The Supply Chain Index (SCI) identifies critical elements as those elements with large throughput rates, as well as greater connectivity. The sum of the scores for a supply chain provides a single metric that roughly captures both the resilience and connectedness of a supply chain. Standardised scores can facilitate cross-comparisons both under current conditions as well as under a changing climate. Identification of key elements along the supply chain may assist in informing adaptation strategies to reduce anticipated future risks posed by climate change. The SCI also provides information on the relative stability of different supply chains based on whether there is a fairly even spread in the individual scores of the top few key elements, compared with a more critical dependence on a few key individual supply chain elements. We use as a case study the Australian southern rock lobster Jasus edwardsii fishery, which is challenged by a number of climate change drivers such as impacts on recruitment and growth due to changes in large-scale and local oceanographic features. The SCI identifies airports, processors and Chinese consumers as the key elements in the lobster supply chain that merit attention to enhance stability and potentially enable growth. We also apply the index to an additional four real-world Australian commercial fishery and two aquaculture industry supply chains to highlight the utility of a systematic method for describing supply chains. Overall, our simple methodological approach to empirically-based supply chain research provides an objective method for comparing the resilience of supply chains and highlighting components that may be critical.

A Quantitative Metric to Identify Critical Elements within Seafood Supply Networks

PubMed Central

Plagányi, Éva E.; van Putten, Ingrid; Thébaud, Olivier; Hobday, Alistair J.; Innes, James; Lim-Camacho, Lilly; Norman-López, Ana; Bustamante, Rodrigo H.; Farmery, Anna; Fleming, Aysha; Frusher, Stewart; Green, Bridget; Hoshino, Eriko; Jennings, Sarah; Pecl, Gretta; Pascoe, Sean; Schrobback, Peggy; Thomas, Linda

2014-01-01

A theoretical basis is required for comparing key features and critical elements in wild fisheries and aquaculture supply chains under a changing climate. Here we develop a new quantitative metric that is analogous to indices used to analyse food-webs and identify key species. The Supply Chain Index (SCI) identifies critical elements as those elements with large throughput rates, as well as greater connectivity. The sum of the scores for a supply chain provides a single metric that roughly captures both the resilience and connectedness of a supply chain. Standardised scores can facilitate cross-comparisons both under current conditions as well as under a changing climate. Identification of key elements along the supply chain may assist in informing adaptation strategies to reduce anticipated future risks posed by climate change. The SCI also provides information on the relative stability of different supply chains based on whether there is a fairly even spread in the individual scores of the top few key elements, compared with a more critical dependence on a few key individual supply chain elements. We use as a case study the Australian southern rock lobster Jasus edwardsii fishery, which is challenged by a number of climate change drivers such as impacts on recruitment and growth due to changes in large-scale and local oceanographic features. The SCI identifies airports, processors and Chinese consumers as the key elements in the lobster supply chain that merit attention to enhance stability and potentially enable growth. We also apply the index to an additional four real-world Australian commercial fishery and two aquaculture industry supply chains to highlight the utility of a systematic method for describing supply chains. Overall, our simple methodological approach to empirically-based supply chain research provides an objective method for comparing the resilience of supply chains and highlighting components that may be critical. PMID:24633147

B38: an all-boron fullerene analogue.

PubMed

Lv, Jian; Wang, Yanchao; Zhu, Li; Ma, Yanming

2014-10-21

Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (∼2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue.

Formation of production structural units within a construction company using the systemic integrated method when implementing high-rise development projects

NASA Astrophysics Data System (ADS)

Lapidus, Azary; Abramov, Ivan

2018-03-01

Development of efficient algorithms for designing future operations is a vital element in construction business. This paper studies various aspects of a methodology required to determine the integration index for construction crews performing various process-related jobs. The main objective of the study outlined in this paper is to define the notion of integration in respect to a construction crew that performs complete cycles of construction and assembly works in order to find the optimal organizational solutions, using the integrated crew algorithm built specifically for that purpose. As seen in the sequence of algorithm elements, it was designed to focus on the key factors affecting the level of integration of a construction crew depending on the value of each of those elements. The multifactor modelling approach is used to assess the KPI of integrated construction crews involved in large-sale high-rise construction projects. The purpose of this study is to develop a theoretical recommendation and a scientific methodological provision of organizational and technological nature to ensure qualitative formation of integrated construction crews to increase their productivity during integrated implementation of multi-task construction phases. The key difference of the proposed solution from the already existing ones is that it requires identification of the degree of impact of each factor, including the change in the qualification level, on the integration index of each separate element in the organizational and technological system in construction (integrated construction crew).

How Many Words Does a Picture Really Tell? Cross-sectional Descriptive Study of Pictogram Evaluation by Youth.

PubMed

Korenevsky, Artyom; Vaillancourt, Régis; Pouliot, Annie; Revol, Marine; Steed, Evan; Besançon, Luc; Wahrendorf, Marit-Saskia; Patel, Jaimisha R

2013-07-01

Communicating health-related instructions with pictograms is useful, but such graphics can be interpreted in different ways. It is crucial to understand which pictogram components are best for accurate communication. To catalogue pictograms used to label drugs in clinical practice; to identify the common graphic elements for defined categories of pictograms, by performing a semiotic analysis (studying how signs are perceived and how they should be designed); to identify the key graphic elements common to pictograms preferred by users; and to develop suggestions for future pictogram design on the basis of users' input. Literature and Internet searches were performed to identify pictograms and pictogram categories. A call for pictograms was also circulated through the International Pharmaceutical Federation (FIP). Youth at a Canadian pediatric hospital were asked to rate pictograms (including storyboards and prescription labels generated by FIP pictogram software) in terms of how best they represented their intended meanings. Pictograms for which at least 80% of participants "somewhat agreed", "agreed", or "strongly agreed" that the graphic conveyed the intended meaning were designated as "preferred" and were selected for analysis. Elements appearing in at least 50% of these preferred pictograms were highlighted as key graphic elements for design of future pictograms. In total, 21 categories were identified for pictograms used in clinical practice, and a total of 204 pictograms were analyzed. Eighty-six participants took part in the survey. For each pictogram category, certain elements were identified as "preferred" and as "key graphic elements", whereas other elements met neither designation. For all 21 pictogram categories, at least 80% of survey respondents agreed that the FIP storyboard conveyed the intended meaning. Certain key, preferred graphic elements are required for pharmaceutical pictograms to convey their intended meaning. The overlap between preferred and key pictogram elements indicates that both must be considered in development of future pictograms. Redesign of existing pictograms with consideration of the best semiotic elements is in progress.

Psychological factors mediate key symptoms of fibromyalgia through their influence on stress.

PubMed

Malin, Katrina; Littlejohn, Geoffrey Owen

2016-09-01

The clinical features of fibromyalgia are associated with various psychological factors, including stress. We examined the hypothesis that the path that psychological factors follow in influencing fibromyalgia symptoms is through their direct effect on stress. Ninety-eight females with ACR 1990 classified fibromyalgia completed the following questionnaires: The Big 5 Personality Inventory, Fibromyalgia Impact Questionnaire, Perceived Stress Scale, Profile of Mood States, Mastery Scale, and Perceived Control of Internal States Scale. SPSS (PASW version 22) was used to perform basic t tests, means, and standard deviations to show difference between symptom characteristics. Pathway analysis using structural equation modelling (Laavan) examined the effect of stress on the relationships between psychological factors and the elements that define the fibromyalgia phenotype. The preferred model showed that the identified path clearly linked the psychological variables of anxiety, neuroticism and mastery, but not internal control, to the three key elements of fibromyalgia, namely pain, fatigue and sleep (p < 0.001), via the person's perceived stress. Confusion, however, did not fit the preferred model. This study confirms that stress is a necessary link in the pathway between certain identified, established and significant psychological factors and key fibromyalgia symptoms. This has implications for the understanding of contributing mechanisms and the clinical care of patients with fibromyalgia.

Shifting the Curve: Fostering Academic Success in a Diverse Student Body

PubMed Central

Herbert-Carter, Janice; Smith, Marjorie; Klement, Brenda; Knight, Brandi Brandon; Anachebe, Ngozi F.

2018-01-01

Problem Diversity in the health care workforce is key to achieving health equity. Although U.S. medical schools have worked to increase the matriculation and academic success of underrepresented minority (URM) students (African Americans, Latinos, others), they have had only limited success. Lower standardized test scores, including on the Medical College Admission Test (MCAT), have been a barrier to matriculation for many URM applicants. Lower subsequent standardized exam scores, including on the United States Medical Licensing Exam Step 1, also have been an impediment to students’ progress, with mean scores for URM students lagging behind those for others. Approach Faculty at the Morehouse School of Medicine developed and implemented interventions to enhance the academic success of their URM students (about 75% are African American, and 5% are from other URM groups). To assess the outcomes of this work, the authors analyzed the MCAT scores and subsequent Step 1 scores of students in the graduating classes of 2009–2014. They also reviewed course evaluations, Graduation Questionnaires, and student and faculty interviews and focus groups. Outcomes Students’ Step 1 scores exceeded those expected based on their MCAT scores. This success was due to three key elements: (1) milieu and mentoring, (2) structure and content of the curriculum, and (3) monitoring. Next Steps A series of mixed-method studies are planned to better discern the core elements of faculty–student relationships that are key to students’ success. Lower test scores are not a fixed attribute; with the elements described, success is attainable for all students. PMID:28678099

Integrable nonlinear Schrödinger system on a lattice with three structural elements in the unit cell

NASA Astrophysics Data System (ADS)

Vakhnenko, Oleksiy O.

2018-05-01

Developing the idea of increasing the number of structural elements in the unit cell of a quasi-one-dimensional lattice as applied to the semi-discrete integrable systems of nonlinear Schrödinger type, we construct the zero-curvature representation for the general integrable nonlinear system on a lattice with three structural elements in the unit cell. The integrability of the obtained general system permits to find explicitly a number of local conservation laws responsible for the main features of system dynamics and in particular for the so-called natural constraints separating the field variables into the basic and the concomitant ones. Thus, considering the reduction to the semi-discrete integrable system of nonlinear Schrödinger type, we revealed the essentially nontrivial impact of concomitant fields on the Poisson structure and on the whole Hamiltonian formulation of system dynamics caused by the nonzero background values of these fields. On the other hand, the zero-curvature representation of a general nonlinear system serves as an indispensable key to the dressing procedure of system integration based upon the Darboux transformation of the auxiliary linear problem and the implicit Bäcklund transformation of field variables. Due to the symmetries inherent to the six-component semi-discrete integrable nonlinear Schrödinger system with attractive-type nonlinearities, the Darboux-Bäcklund dressing scheme is shown to be simplified considerably, giving rise to the appropriately parameterized multi-component soliton solution consisting of six basic and four concomitant components.

Controlled cobalt doping in the spinel structure of magnetosome magnetite: New evidences from element- and site-specific XMCD analyses

NASA Astrophysics Data System (ADS)

Pan, Y.; LI, J.; Menguy, N.; Arrio, M. A.; Sainctavit, P.; Juhin, A.; Wang, Y.; Chen, H.; Bunau, O.; Otero, E.; Ohresser, P.

2016-12-01

Controlled cobalt doping in the spinel structure of magnetosome magnetite: New evidences from element- and site-specific XMCD analyses Jinhua Li1,2*, Nicolas Menguy2,3, Marie-Anne Arrio3, Philippe Sainctavit3,4, Amélie Juhin3, Yinzhao Wang1,2, Haitao Chen5, Oana Bunau3, Edwige Otero4, Philippe Ohresser4, Yongxin Pan1,21Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China. 2France-China Biomineralization and Nano-structures Laboratory, Chinese Academy of Sciences, Beijing 100029, China. 3IMPMC, CNRS UMR 7590, Sorbonne Universités, MNHN, UPMC, IRD UMR 206, 75005 Paris, France. 4Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, 91192 Gif-sur-Yvette Cedex, France. 5Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China *To whom correspondence may be addressed. Email: lijinhua@mail.iggcas.ac.cnThe biomineralization of magnetite nanocrystals (called magnetosomes) by magnetotactic bacteria (MTB) has attracted intense interest in biology, geology and materials science. Great efforts have been recently made in producing transition metal-doped magnetosomes with modified magnetic properties for a range of applications. However, the coordination chemistry and magnetism of such metal-doped magnetosomes still remains largely unknown. Here, we present new evidences from X-ray magnetic circular dichroism (XMCD) for element- and site-specific magnetic analyses that cobalt is incorporated in the spinel structure of the magnetosomes within Magnetospirillum magneticum AMB-1 through the replacement of Fe2+ ions by Co2+ ions in octahedral (Oh) sites of magnetite. Compared with non-doped one, cobalt-doped magnetosome sample has lower Verwey transition temperature and larger magnetic coercivity, related to the amount of doped cobalt. This study this study indicates a biologically controlled process on cobalt doping and magnetic alteration by MTB system. ACKNOWLEDGMENTS. This study was financially supported by the NSFC projects (grants 41374004, 41522402, and 41330104) and the French program ANR-blanc (project MS-MCNP and project SWITCH). JHL is grateful for the Open Project Support from the State Key Laboratory of Lithospheric Evolution (IGGCAS).

The effect of relativity on stability of Copernicium phases, their electronic structure and mechanical properties

NASA Astrophysics Data System (ADS)

Čenčariková, Hana; Legut, Dominik

2018-05-01

The phase stability of the various crystalline structures of the super-heavy element Copernicium was determined based on the first-principles calculations with different levels of the relativistic effects. We utilized the Darwin term, mass-velocity, and spin-orbit interaction with the single electron framework of the density functional theory while treating the exchange and correlation effects using local density approximations. It is found that the spin-orbit coupling is the key component to stabilize the body-centered cubic (bcc) structure over the hexagonal closed packed (hcp) structure, which is in accord with Sol. Stat. Comm. 152 (2012) 530, but in contrast to Atta-Fynn and Ray (2015) [11], Gaston et al. (2007) [10], Papaconstantopoulos (2015) [9]. It seems that the main role here is the correct description of the semi-core relativistic 6p1/2 orbitals. The all other investigated structures, i.e. face-centered cubic (fcc) , simple cubic (sc) as well as rhombohedral (rh) structures are higher in energy. The criteria of mechanical stability were investigated based on the calculated elastic constants, identifying the phase instability of fcc and rh structures, but surprisingly confirm the stability of the energetically higher sc structure. In addition, the pressure-induced structural transition between two stable sc and bcc phases has been detected. The ground-state bcc structure exhibits the highest elastic anisotropy from single elements of the Periodic table. At last, we support the experimental findings that Copernicium is a metal.

Governance versus government: drug consumption rooms in Australia and the UK.

PubMed

Zampini, Giulia Federica

2014-09-01

To evaluate, through a case study, the extent to which elements of governance and elements of government are influential in determining the implementation or non-implementation of a drugs intervention. Comparative analysis of the case of a drug consumption room in the UK (England) and Australia (New South Wales), including 16 semi-structured interviews with key stakeholders and analysis of relevant documents according to characteristic features of governance and government (power decentralisation, power centralisation, independent self-organising policy networks, use of evidence, top-down steering/directing, legislation). Characteristic features of both governance and government are found in the data. Elements of governance are more prominent in New South Wales, Australia than in England, UK, where government prevails. Government is seen as the most important actor at play in the making, or absence, of drug consumption rooms. Both governance and government are useful frameworks in conceptualising the policy process. The governance narrative risks overlooking the importance of traditional government structures. In the case of drug consumption rooms in the UK and Australia, a focus on government is shown to have been crucial in determining whether the intervention was implemented. Copyright © 2014 Elsevier B.V. All rights reserved.

High-resolution structure of the Escherichia coli ribosome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noeske, Jonas; Wasserman, Michael R.; Terry, Daniel S.

Protein synthesis by the ribosome is highly dependent on the ionic conditions in the cellular environment, but the roles of ribosome solvation remain poorly understood. Moreover, the function of modifications to ribosomal RNA and ribosomal proteins are unclear. Here we present the structure of the Escherichia coli 70S ribosome to 2.4 Å resolution. The structure reveals details of the ribosomal subunit interface that are conserved in all domains of life, and suggest how solvation contributes to ribosome integrity and function. The structure also suggests how the conformation of ribosomal protein uS12 likely impacts its contribution to messenger RNA decoding. Inmore » conclusion, this structure helps to explain the phylogenetic conservation of key elements of the ribosome, including posttranscriptional and posttranslational modifications and should serve as a basis for future antibiotic development.« less

High-resolution structure of the Escherichia coli ribosome

DOE PAGES

Noeske, Jonas; Wasserman, Michael R.; Terry, Daniel S.; ...

2015-03-16

Protein synthesis by the ribosome is highly dependent on the ionic conditions in the cellular environment, but the roles of ribosome solvation remain poorly understood. Moreover, the function of modifications to ribosomal RNA and ribosomal proteins are unclear. Here we present the structure of the Escherichia coli 70S ribosome to 2.4 Å resolution. The structure reveals details of the ribosomal subunit interface that are conserved in all domains of life, and suggest how solvation contributes to ribosome integrity and function. The structure also suggests how the conformation of ribosomal protein uS12 likely impacts its contribution to messenger RNA decoding. Inmore » conclusion, this structure helps to explain the phylogenetic conservation of key elements of the ribosome, including posttranscriptional and posttranslational modifications and should serve as a basis for future antibiotic development.« less

The J-Staff System, Network Synchronisation and Noise

DTIC Science & Technology

2014-06-01

GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S... work . A key challenge of such structures is their tendency to fall into extreme dynamical modes. One is a ‘two-speed’ mode, where units interacting with...longer term planning, led by the J5 Planning Branch, fall into a slow cycle of work , while those entities interacting predominately with operations

Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Michael W. M.; Phillips, Nicholas W.; van Riessen, Grant A.

2016-08-11

Owing to its extreme sensitivity, quantitative mapping of elemental distributionsviaX-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated.

Ontology Alignment Architecture for Semantic Sensor Web Integration

PubMed Central

Fernandez, Susel; Marsa-Maestre, Ivan; Velasco, Juan R.; Alarcos, Bernardo

2013-01-01

Sensor networks are a concept that has become very popular in data acquisition and processing for multiple applications in different fields such as industrial, medicine, home automation, environmental detection, etc. Today, with the proliferation of small communication devices with sensors that collect environmental data, semantic Web technologies are becoming closely related with sensor networks. The linking of elements from Semantic Web technologies with sensor networks has been called Semantic Sensor Web and has among its main features the use of ontologies. One of the key challenges of using ontologies in sensor networks is to provide mechanisms to integrate and exchange knowledge from heterogeneous sources (that is, dealing with semantic heterogeneity). Ontology alignment is the process of bringing ontologies into mutual agreement by the automatic discovery of mappings between related concepts. This paper presents a system for ontology alignment in the Semantic Sensor Web which uses fuzzy logic techniques to combine similarity measures between entities of different ontologies. The proposed approach focuses on two key elements: the terminological similarity, which takes into account the linguistic and semantic information of the context of the entity's names, and the structural similarity, based on both the internal and relational structure of the concepts. This work has been validated using sensor network ontologies and the Ontology Alignment Evaluation Initiative (OAEI) tests. The results show that the proposed techniques outperform previous approaches in terms of precision and recall. PMID:24051523

Ontology alignment architecture for semantic sensor Web integration.

PubMed

Fernandez, Susel; Marsa-Maestre, Ivan; Velasco, Juan R; Alarcos, Bernardo

2013-09-18

Sensor networks are a concept that has become very popular in data acquisition and processing for multiple applications in different fields such as industrial, medicine, home automation, environmental detection, etc. Today, with the proliferation of small communication devices with sensors that collect environmental data, semantic Web technologies are becoming closely related with sensor networks. The linking of elements from Semantic Web technologies with sensor networks has been called Semantic Sensor Web and has among its main features the use of ontologies. One of the key challenges of using ontologies in sensor networks is to provide mechanisms to integrate and exchange knowledge from heterogeneous sources (that is, dealing with semantic heterogeneity). Ontology alignment is the process of bringing ontologies into mutual agreement by the automatic discovery of mappings between related concepts. This paper presents a system for ontology alignment in the Semantic Sensor Web which uses fuzzy logic techniques to combine similarity measures between entities of different ontologies. The proposed approach focuses on two key elements: the terminological similarity, which takes into account the linguistic and semantic information of the context of the entity's names, and the structural similarity, based on both the internal and relational structure of the concepts. This work has been validated using sensor network ontologies and the Ontology Alignment Evaluation Initiative (OAEI) tests. The results show that the proposed techniques outperform previous approaches in terms of precision and recall.

Spatial and Temporal Dynamics in Air Pollution Exposure Assessment

PubMed Central

Dias, Daniela; Tchepel, Oxana

2018-01-01

Analyzing individual exposure in urban areas offers several challenges where both the individual’s activities and air pollution levels demonstrate a large degree of spatial and temporal dynamics. This review article discusses the concepts, key elements, current developments in assessing personal exposure to urban air pollution (seventy-two studies reviewed) and respective advantages and disadvantages. A new conceptual structure to organize personal exposure assessment methods is proposed according to two classification criteria: (i) spatial-temporal variations of individuals’ activities (point-fixed or trajectory based) and (ii) characterization of air quality (variable or uniform). This review suggests that the spatial and temporal variability of urban air pollution levels in combination with indoor exposures and individual’s time-activity patterns are key elements of personal exposure assessment. In the literature review, the majority of revised studies (44 studies) indicate that the trajectory based with variable air quality approach provides a promising framework for tackling the important question of inter- and intra-variability of individual exposure. However, future quantitative comparison between the different approaches should be performed, and the selection of the most appropriate approach for exposure quantification should take into account the purpose of the health study. This review provides a structured basis for the intercomparing of different methodologies and to make their advantages and limitations more transparent in addressing specific research objectives. PMID:29558426

Effect of fire-induced damage on the uniaxial strength characteristics of solid timber: A numerical study

NASA Astrophysics Data System (ADS)

Hopkin, D. J.; El-Rimawi, J.; Lennon, T.; Silberschmidt, V. V.

2011-07-01

The advent of the structural Eurocodes has allowed civil engineers to be more creative in the design of structures exposed to fire. Rather than rely upon regulatory guidance and prescriptive methods engineers are now able to use such codes to design buildings on the basis of credible design fires rather than accepted unrealistic standard-fire time-temperature curves. Through this process safer and more efficient structural designs are achievable. The key development in enabling performance-based fire design is the emergence of validated numerical models capable of predicting the mechanical response of a whole building or sub-assemblies at elevated temperature. In such a way, efficiency savings have been achieved in the design of steel, concrete and composite structures. However, at present, due to a combination of limited fundamental research and restrictions in the UK National Annex to the timber Eurocode, the design of fire-exposed timber structures using numerical modelling techniques is not generally undertaken. The 'fire design' of timber structures is covered in Eurocode 5 part 1.2 (EN 1995-1-2). In this code there is an advanced calculation annex (Annex B) intended to facilitate the implementation of numerical models in the design of fire-exposed timber structures. The properties contained in the code can, at present, only be applied to standard-fire exposure conditions. This is due to existing limitations related to the available thermal properties which are only valid for standard fire exposure. In an attempt to overcome this barrier the authors have proposed a 'modified conductivity model' (MCM) for determining the temperature of timber structural elements during the heating phase of non-standard fires. This is briefly outlined in this paper. In addition, in a further study, the MCM has been implemented in a coupled thermo-mechanical analysis of uniaxially loaded timber elements exposed to non-standard fires. The finite element package DIANA was adopted with plane-strain elements assuming two-dimensional heat flow. The resulting predictions of failure time for given levels of load are discussed and compared with the simplified 'effective cross section' method presented in EN 1995-1-2.

Psychotherapy training: Suggestions for core ingredients and future research.

PubMed

Boswell, James F; Castonguay, Louis G

2007-12-01

Despite our considerable depth and breadth of empirical knowledge on psychotherapy process and outcome, research on psychotherapy training is somewhat lacking. We would argue, however, that the scientist-practitioner model should not only guide practice, but also the way our field approaches training. In this paper we outline our perspective on the crucial elements of psychotherapy training based on available evidence, theory, and clinical experience, focusing specifically on the structure, key components, and important skills to be learned in a successful training program. In addition, we derive specific research directions based on the crucial elements of our proposed training perspective, and offer general considerations for research on training, including method and measurement issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

Development of a preprototype thermoelectric integrated membrane evaporation subsystem for water recovery

NASA Technical Reports Server (NTRS)

Winkler, H. E.; Roebelen, G. J., Jr.

1980-01-01

A three-man urine water recovery preprototype subsystem using a new concept to provide efficient potable water recovery from waste fluids on extended duration space flights has been designed, fabricated, and tested. Low power, compactness, and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber polysulfone membrane evaporator with a thermoelectric heat pump. Application and integration of these key elements have solved problems inherent in previous reclamation subsystem designs. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than a waste liquid recirculation pump and a product water withdrawal pump. Tubular membranes provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery.

Babinet-Inverted Optical Yagi-Uda Antenna for Unidirectional Radiation to Free Space

NASA Astrophysics Data System (ADS)

Kim, Jineun; Roh, Young-Geun; Cheon, Sangmo; Choe, Jong-Ho; Lee, Jongcheon; Lee, Jaesoong; Jeong, Heejeong; Kim, Un Jeong; Park, Yeonsang; Song, In Yong; Park, Q.-Han; Hwang, Sung Woo; Kim, Kinam; Lee, Chang-Won

2014-06-01

Plasmonic nanoantennas are key elements in nanophotonics capable of directing radiation or enhancing the transition rate of a quantum emitter. Slot-type magnetic-dipole nanoantennas, which are complementary structures of typical electric-dipole-type antennas, have received little attention, leaving their antenna properties largely unexplored. Here we present a novel magnetic-dipole-fed multi-slot optical Yagi-Uda antenna. By engineering the relative phase of the interacting surface plasmon polaritons between the slot elements, we demonstrate that the optical antenna exhibits highly unidirectional radiation to free space. The unique features of the slot-based magnetic nanoantenna provide a new possibility of achieving integrated features such as energy transfer from one waveguide to another by working as a future optical via.

Rain Volume Estimation over Areas Using Satellite and Radar Data

NASA Technical Reports Server (NTRS)

Doneaud, A. A.; Miller, J. R., Jr.; Johnson, L. R.; Vonderhaar, T. H.; Laybe, P.

1984-01-01

The application of satellite data to a recently developed radar technique used to estimate convective rain volumes over areas on a dry environment (the northern Great Plains) is discussed. The area time integral technique (ATI) provides a means of estimating total rain volumes over fixed and floating target areas of the order of 1,000 to 100,000 km(2) for clusters lasting 40 min. The basis of the method is the existence of a strong correlation between the area coverage integrated over the lifetime of the storm (ATI) and the rain volume. One key element in this technique is that it does not require the consideration of the structure of the radar intensities inside the area coverage to generate rain volumes, but only considers the rain event per se. This fact might reduce or eliminate some sources of error in applying the technique to satellite data. The second key element is that the ATI once determined can be converted to total rain volume by using a constant factor (average rain rate) for a given locale.

Ultrasonic characterization of the fiber-matrix interfacial bond in aerospace composites.

PubMed

Aggelis, D G; Kleitsa, D; Matikas, T E

2013-01-01

The properties of advanced composites rely on the quality of the fiber-matrix bonding. Service-induced damage results in deterioration of bonding quality, seriously compromising the load-bearing capacity of the structure. While traditional methods to assess bonding are destructive, herein a nondestructive methodology based on shear wave reflection is numerically investigated. Reflection relies on the bonding quality and results in discernable changes in the received waveform. The key element is the "interphase" model material with varying stiffness. The study is an example of how computational methods enhance the understanding of delicate features concerning the nondestructive evaluation of materials used in advanced structures.

Research on electromechanical resonance of two-axis tracking system

NASA Astrophysics Data System (ADS)

Zhao, Zhi-ming; Xue, Ying-jie; Zeng, Shu-qin; Li, Zhi-guo

2017-02-01

The multi-axes synchronous system about the spatial two-axis turntable is the key equipment for semi-physical simulation and test in aerospace. In this paper, the whole structure design of the turntable is created by using Solidworks, then putting the three-dimensional solid model into ANSYS to build the finite element model. The software ANSYS is used to do the simulation about the static and dynamic analysis of two-axis turntable. Based on the modal analysis, we can forecast the inherent frequencies and the mode of vibration during the launch conditions which is very important to the design and safety of the structure.

Model Updating of Complex Structures Using the Combination of Component Mode Synthesis and Kriging Predictor

PubMed Central

Li, Yan; Wang, Dejun; Zhang, Shaoyi

2014-01-01

Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM) to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters. PMID:24634612

Modeling and Evaluation of Canted Coil Springs as High Temperature Seal Preloading Devices

NASA Technical Reports Server (NTRS)

Oswald, Jay J.; Mullen, Robert L.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

2004-01-01

Future reusable launch vehicles will require advanced structural seals. This includes propulsion seals along edges and hinge lines in hypersonic engines, and control surface seals for movable flaps and elevons on proposed reentry vehicles. Seals must remain in sealing engagement with opposing surfaces, for multiple missions, even though the seal gap may be opening and closing due to thermal and structural loads. To meet this requirement either the seals themselves must be resilient or there must be a resilient structural element behind the seals. Case Western Reserve University is working with NASA s Glenn Research Center to develop more resilient high temperature seal components and preloading devices. Results are presented for a finite element analysis of a canted coil spring that is being considered as a high temperature seal preloading device. This type of spring is a leading candidate due to its ability to provide nearly constant force over a large deflection. The finite element analyses were verified by comparing them to experimental results of canted coil springs of three different stiffnesses, measured at Glenn Research Center. Once validated the parameterized model was combined with a scripting algorithm to assess the effects of key spring design variables (wire diameter, coils per inch, cant amplitude, eccentricity, and spring width) on spring stiffness and maximum Von Mises stress to aid in subsequent design.

Adaptive dynamical networks

NASA Astrophysics Data System (ADS)

Maslennikov, O. V.; Nekorkin, V. I.

2017-10-01

Dynamical networks are systems of active elements (nodes) interacting with each other through links. Examples are power grids, neural structures, coupled chemical oscillators, and communications networks, all of which are characterized by a networked structure and intrinsic dynamics of their interacting components. If the coupling structure of a dynamical network can change over time due to nodal dynamics, then such a system is called an adaptive dynamical network. The term ‘adaptive’ implies that the coupling topology can be rewired; the term ‘dynamical’ implies the presence of internal node and link dynamics. The main results of research on adaptive dynamical networks are reviewed. Key notions and definitions of the theory of complex networks are given, and major collective effects that emerge in adaptive dynamical networks are described.

Care coordination in accountable care organizations: moving beyond structure and incentives.

PubMed

Press, Matthew J; Michelow, Marilyn D; MacPhail, Lucy H

2012-12-01

Accountable care organizations (ACOs) are considered by many to be a key component of healthcare delivery system improvement. One expectation is that the structural elements of the ACO model, including clinical integration and financial accountability, will lead to better coordination of care for patients. But, while structure and incentives may facilitate the delivery of coordinated care, they will not necessarily ensure that care coordination is done well. For that, physicians and other healthcare providers within ACOs must possess and utilize specific skills, particularly in the areas of collaboration, communication, and teamwork. In this article, we present strategies in 3 domains--training, support tools, and organizational culture--that ACOs can implement to foster the development of these skills and support their use in clinical practice.

Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

PubMed

Li, Yasong; Gates, Byron D; Menon, Carlo

2015-08-05

The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

Topological Structures in Multiferroics - Domain Walls, Skyrmions and Vortices

DOE PAGES

Seidel, Jan; Vasudevan, Rama K.; Valanoor, Nagarajan

2015-12-15

Topological structures in multiferroic materials have recently received considerable attention because of their potential use as nanoscale functional elements. Their reduced size in conjunction with exotic arrangement of the ferroic order parameter and potential order parameter coupling allows for emergent and unexplored phenomena in condensed matter and functional materials systems. This will lead to exciting new fundamental discoveries as well as application concepts that exploit their response to external stimuli such as mechanical strain, electric and magnetic fields. In this review we capture the current development of this rapidly moving field with specific emphasis on key achievements that have castmore » light on how such topological structures in multiferroic materials systems can be exploited for use in complex oxide nanoelectronics and spintronics.« less

Analysis of Relationships between the Level of Errors in Leg and Monofin Movement and Stroke Parameters in Monofin Swimming

PubMed Central

Rejman, Marek

2013-01-01

The aim of this study was to analyze the error structure in propulsive movements with regard to its influence on monofin swimming speed. The random cycles performed by six swimmers were filmed during a progressive test (900m). An objective method to estimate errors committed in the area of angular displacement of the feet and monofin segments was employed. The parameters were compared with a previously described model. Mutual dependences between the level of errors, stroke frequency, stroke length and amplitude in relation to swimming velocity were analyzed. The results showed that proper foot movements and the avoidance of errors, arising at the distal part of the fin, ensure the progression of swimming speed. The individual stroke parameters distribution which consists of optimally increasing stroke frequency to the maximal possible level that enables the stabilization of stroke length leads to the minimization of errors. Identification of key elements in the stroke structure based on the analysis of errors committed should aid in improving monofin swimming technique. Key points The monofin swimming technique was evaluated through the prism of objectively defined errors committed by the swimmers. The dependences between the level of errors, stroke rate, stroke length and amplitude in relation to swimming velocity were analyzed. Optimally increasing stroke rate to the maximal possible level that enables the stabilization of stroke length leads to the minimization of errors. Propriety foot movement and the avoidance of errors arising at the distal part of fin, provide for the progression of swimming speed. The key elements improving monofin swimming technique, based on the analysis of errors committed, were designated. PMID:24149742

The identification of clinically important elements within medical journal abstracts: Patient-Population-Problem, Exposure-Intervention, Comparison, Outcome, Duration and Results (PECODR).

PubMed

Dawes, Martin; Pluye, Pierre; Shea, Laura; Grad, Roland; Greenberg, Arlene; Nie, Jian-Yun

2007-01-01

Information retrieval in primary care is becoming more difficult as the volume of medical information held in electronic databases expands. The lexical structure of this information might permit automatic indexing and improved retrieval. To determine the possibility of identifying the key elements of clinical studies, namely Patient-Population-Problem, Exposure-Intervention, Comparison, Outcome, Duration and Results (PECODR), from abstracts of medical journals. We used a convenience sample of 20 synopses from the journal Evidence-Based Medicine (EBM) and their matching original journal article abstracts obtained from PubMed. Three independent primary care professionals identified PECODR-related extracts of text. Rules were developed to define each PECODR element and the selection process of characters, words, phrases and sentences. From the extracts of text related to PECODR elements, potential lexical patterns that might help identify those elements were proposed and assessed using NVivo software. A total of 835 PECODR-related text extracts containing 41,263 individual text characters were identified from 20 EBM journal synopses. There were 759 extracts in the corresponding PubMed abstracts containing 31,947 characters. PECODR elements were found in nearly all abstracts and synopses with the exception of duration. There was agreement on 86.6% of the extracts from the 20 EBM synopses and 85.0% on the corresponding PubMed abstracts. After consensus this rose to 98.4% and 96.9% respectively. We found potential text patterns in the Comparison, Outcome and Results elements of both EBM synopses and PubMed abstracts. Some phrases and words are used frequently and are specific for these elements in both synopses and abstracts. Results suggest a PECODR-related structure exists in medical abstracts and that there might be lexical patterns specific to these elements. More sophisticated computer-assisted lexical-semantic analysis might refine these results, and pave the way to automating PECODR indexing, and improve information retrieval in primary care.

Layer-by-layer assembly of patchy particles as a route to nontrivial structures

NASA Astrophysics Data System (ADS)

Patra, Niladri; Tkachenko, Alexei V.

2017-08-01

We propose a strategy for robust high-quality self-assembly of nontrivial periodic structures out of patchy particles and investigate it with Brownian dynamics simulations. Its first element is the use of specific patch-patch and shell-shell interactions between the particles, which can be implemented through differential functionalization of patched and shell regions with specific DNA strands. The other key element of our approach is the use of a layer-by-layer protocol that allows one to avoid the formation of undesired random aggregates. As an example, we design and self-assemble in silico a version of a double diamond lattice in which four particle types are arranged into bcc crystal made of four fcc sublattices. The lattice can be further converted to cubic diamond by selective removal of the particles of certain types. Our results demonstrate that by combining the directionality, selectivity of interactions, and the layer-by-layer protocol, a high-quality robust self-assembly can be achieved.

Layer-by-layer assembly of patchy particles as a route to nontrivial structures

DOE PAGES

Patra, Niladri; Tkachenko, Alexei V.

2017-08-02

Here, we propose a strategy for robust high-quality self-assembly of nontrivial periodic structures out of patchy particles and investigate it with Brownian dynamics simulations. Its first element is the use of specific patch-patch and shell-shell interactions between the particles, which can be implemented through differential functionalization of patched and shell regions with specific DNA strands. The other key element of our approach is the use of a layer-by-layer protocol that allows one to avoid the formation of undesired random aggregates. As an example, we design and self-assemble in silico a version of a double diamond lattice in which four particlemore » types are arranged into bcc crystal made of four fcc sublattices. The lattice can be further converted to cubic diamond by selective removal of the particles of certain types. These results demonstrate that by combining the directionality, selectivity of interactions, and the layer-by-layer protocol, a high-quality robust self-assembly can be achieved.« less

Polarization-Modulated Second Harmonic Generation Microscopy in Collagen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoller, P C

Collagen is a key structural protein in the body; several pathological conditions lead to changes in collagen. Among imaging modalities that can be used in vivo, second harmonic generation (SHG) microscopy has a key advantage: it provides {approx}1 {micro}m resolution information about collagen structure as a function of depth. A new technique--polarization-modulated SHG--is presented: it permits simultaneous measurement of collagen orientation, of a lower bound on the magnitude of the second order nonlinear susceptibility tensor, and of the ratio of the two independent elements in this tensor. It is applied to characterizing SHG in collagen and to determining effects ofmore » biologically relevant changes in collagen structure. The magnitude of the second harmonic signal in two dimensional images varies with position even in structurally homogeneous tissue; this phenomenon is due to interference between second harmonic light generated by neighboring fibrils, which are randomly oriented parallel or anti-parallel to each other. Studies in which focal spot size was varied indicated that regions where fibrils are co-oriented are less than {approx}1.5 {micro}m in diameter. A quartz reference was used to determine the spot size as well as a lower limit (d{sub xxx} > 0.3 pm/V) for the magnitude of the second order nonlinear susceptibility. The ratio of the two independent tensor elements ranged between d{sub XYY}/d{sub XXX} = 0.60 and 0.75. SHG magnitude alone was not useful for identifying structural anomalies in collagenous tissue. Instead, changes in the polarization dependence of SHG were used to analyze biologically relevant perturbations in collagen structure. Changes in polarization dependence were observed in dehydrated samples, but not in highly crosslinked samples, despite significant alterations in packing structure. Complete thermal denaturation and collagenase digestion produced samples with no detectable SHG signal. Collagen orientation was measured in thin samples of several different tissues in transmission mode as well as at different depths (up to 200 {micro}m) in thick samples in reflection mode; birefringence had no effect on the measurement. These studies showed that SHG microscopy was capable of detecting pathophysiological changes in collagen structure, suggesting that this technique has potential clinical applications.« less

Strain Mediated Adaptation Is Key for Myosin Mechanochemistry: Discovering General Rules for Motor Activity.

PubMed

Jana, Biman; Onuchic, José N

2016-08-01

A structure-based model of myosin motor is built in the same spirit of our early work for kinesin-1 and Ncd towards physical understanding of its mechanochemical cycle. We find a structural adaptation of the motor head domain in post-powerstroke state that signals faster ADP release from it compared to the same from the motor head in the pre-powerstroke state. For dimeric myosin, an additional forward strain on the trailing head, originating from the postponed powerstroke state of the leading head in the waiting state of myosin, further increases the rate of ADP release. This coordination between the two heads is the essence of the processivity of the cycle. Our model provides a structural description of the powerstroke step of the cycle as an allosteric transition of the converter domain in response to the Pi release. Additionally, the variation in structural elements peripheral to catalytic motor domain is the deciding factor behind diverse directionalities of myosin motors (myosin V & VI). Finally, we observe that there are general rules for functional molecular motors across the different families. Allosteric structural adaptation of the catalytic motor head in different nucleotide states is crucial for mechanochemistry. Strain-mediated coordination between motor heads is essential for processivity and the variation of peripheral structural elements is essential for their diverse functionalities.

Strain Mediated Adaptation Is Key for Myosin Mechanochemistry: Discovering General Rules for Motor Activity

PubMed Central

Jana, Biman; Onuchic, José N.

2016-01-01

A structure-based model of myosin motor is built in the same spirit of our early work for kinesin-1 and Ncd towards physical understanding of its mechanochemical cycle. We find a structural adaptation of the motor head domain in post-powerstroke state that signals faster ADP release from it compared to the same from the motor head in the pre-powerstroke state. For dimeric myosin, an additional forward strain on the trailing head, originating from the postponed powerstroke state of the leading head in the waiting state of myosin, further increases the rate of ADP release. This coordination between the two heads is the essence of the processivity of the cycle. Our model provides a structural description of the powerstroke step of the cycle as an allosteric transition of the converter domain in response to the Pi release. Additionally, the variation in structural elements peripheral to catalytic motor domain is the deciding factor behind diverse directionalities of myosin motors (myosin V & VI). Finally, we observe that there are general rules for functional molecular motors across the different families. Allosteric structural adaptation of the catalytic motor head in different nucleotide states is crucial for mechanochemistry. Strain-mediated coordination between motor heads is essential for processivity and the variation of peripheral structural elements is essential for their diverse functionalities. PMID:27494025

Multiple conformations are a conserved and regulatory feature of the RB1 5′ UTR

PubMed Central

Kutchko, Katrina M.; Sanders, Wes; Ziehr, Ben; Phillips, Gabriela; Solem, Amanda; Halvorsen, Matthew; Weeks, Kevin M.; Moorman, Nathaniel

2015-01-01

Folding to a well-defined conformation is essential for the function of structured ribonucleic acids (RNAs) like the ribosome and tRNA. Structured elements in the untranslated regions (UTRs) of specific messenger RNAs (mRNAs) are known to control expression. The importance of unstructured regions adopting multiple conformations, however, is still poorly understood. High-resolution SHAPE-directed Boltzmann suboptimal sampling of the Homo sapiens Retinoblastoma 1 (RB1) 5′ UTR yields three distinct conformations compatible with the experimental data. Private single nucleotide variants (SNVs) identified in two patients with retinoblastoma each collapse the structural ensemble to a single but distinct well-defined conformation. The RB1 5′ UTRs from Bos taurus (cow) and Trichechus manatus latirostris (manatee) are divergent in sequence from H. sapiens (human) yet maintain structural compatibility with high-probability base pairs. SHAPE chemical probing of the cow and manatee RB1 5′ UTRs reveals that they also adopt multiple conformations. Luciferase reporter assays reveal that 5′ UTR mutations alter RB1 expression. In a traditional model of disease, causative SNVs disrupt a key structural element in the RNA. For the subset of patients with heritable retinoblastoma-associated SNVs in the RB1 5′ UTR, the absence of multiple structures is likely causative of the cancer. Our data therefore suggest that selective pressure will favor multiple conformations in eukaryotic UTRs to regulate expression. PMID:25999316

Method for Controlling Space Transportation System Life Cycle Costs

NASA Technical Reports Server (NTRS)

McCleskey, Carey M.; Bartine, David E.

2006-01-01

A structured, disciplined methodology is required to control major cost-influencing metrics of space transportation systems during design and continuing through the test and operations phases. This paper proposes controlling key space system design metrics that specifically influence life cycle costs. These are inclusive of flight and ground operations, test, and manufacturing and infrastructure. The proposed technique builds on today's configuration and mass properties control techniques and takes on all the characteristics of a classical control system. While the paper does not lay out a complete math model, key elements of the proposed methodology are explored and explained with both historical and contemporary examples. Finally, the paper encourages modular design approaches and technology investments compatible with the proposed method.

Science and Technology Review June 2000

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Pruneda, J.H.

2000-06-01

This issue contains the following articles: (1) ''Accelerating on the ASCI Challenge''. (2) ''New Day Daws in Supercomputing'' When the ASCI White supercomputer comes online this summer, DOE's Stockpile Stewardship Program will make another significant advanced toward helping to ensure the safety, reliability, and performance of the nation's nuclear weapons. (3) ''Uncovering the Secrets of Actinides'' Researchers are obtaining fundamental information about the actinides, a group of elements with a key role in nuclear weapons and fuels. (4) ''A Predictable Structure for Aerogels''. (5) ''Tibet--Where Continents Collide''.

Improving attachments of remotely-deployed dorsal fin-mounted tags: tissue structure, hydrodynamics, in situ performance, and tagged-animal follow-up

DTIC Science & Technology

2012-09-30

and then design and test improved retention systems 4. Conduct follow-up studies of tagged whales to accurately quantify wound healing and the...behavior (e.g., beaked whale versus melon-headed whale). 3. In situ behavior of retention system elements (Key individuals: Andrews, Schorr...Although we have a good idea of how the LIMPET retention system operates when first implanted, we do not fully understand the mechanics in a living fin

Improving Attachments of Remotely-Deployed Dorsal Fin-Mounted Tags: Tissue Structure, Hydrodynamics, in Situ Performance, and Tagged-Animal Follow-up

DTIC Science & Technology

2012-09-30

design and test improved retention systems 4. Conduct follow-up studies of tagged whales to accurately quantify wound healing and the effects of...e.g., beaked whale versus melon-headed whale). 3. In situ behavior of retention system elements (Key individuals: Andrews, Schorr, Hanson, Howle...have a good idea of how the LIMPET retention system operates when first implanted, we do not fully understand the mechanics in a living fin. Therefore

Improving attachments of remotely-deployed dorsal fin-mounted tags: tissue structure, hydrodynamics, in situ performance, and tagged-animal follow-up

DTIC Science & Technology

2011-09-01

Examine the in situ performance of our current attachment devices and then design and test improved retention systems Report Documentation Page Form...behavior (e.g., beaked whale versus melon-headed whale). 3. In situ behavior of retention system elements (Key individuals: Andrews, Schorr...Although we have a good idea of how the LIMPET retention system operates when first implanted, we do not fully understand the mechanics in a living fin

Application of HSE management in a multi-cultural environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamki, A.M.N.; Binks, S.L.M.

1996-11-01

This paper addresses the key elements of Petroleum Development Oman L.L.C.`s HSE programmes and the systems employed to structure their application. An improvement in HSE performance with the introduction of HSE programmes and systems is demonstrated. Special emphasis is given to some of the difficulties experienced with application of the systems in a multi-national/cultural workforce. Finally, examples are given of the techniques adopted to promote the application of HSE management in the workforce, with particular emphasis on communication and training.

Dynamic Loading and Characterization of Fiber-Reinforced Composites

NASA Astrophysics Data System (ADS)

Sierakowski, Robert L.; Chaturvedi, Shive K.

1997-02-01

Emphasizing polymer based fiber-reinforced composites, this book is designed to provide readers with a significant understanding of the complexities involved in characterizing dynamic events and the corresponding response of advanced fiber composite materials and structures. These elements include dynamic loading devices, material properties characterization, analytical and experimental techniques to assess the damage and failure modes associated with various dynamic loading events. Concluding remarks are presented throughout the text which summarize key points and raise issues related to important research needed.

Improving Attachments of Remotely-Deployed Dorsal Fin-Mounted Tags: Tissue Structure, Hydrodynamics, in Situ Performance, and Tagged-Animal Follow-Up

DTIC Science & Technology

2010-09-30

and let them see a whale tagging operation first hand in Puget Sound ; we polished up our objectives and refined our methods, and have come up with...examination based on differences such as size/shape of the dorsal fin (e.g., melon-headed versus killer whale ), taxonomic grouping (i.e., odontocetes...navy sonar - beaked whales ; ship strikes - fin whales ; ecological role – killer whales ). 3. In situ behavior of retention system elements (Key

Integrated Nuclear and Conventional Theater Warfare Simulation (INWARS) Level III Specifications. Volume III. Air Combat Modeling.

DTIC Science & Technology

1978-07-24

will include an implicit air function that will perform the air planning and requesting associated with the various headquarters. The decision structure...air headquarters (The ATAF/TAA) will be included in the CIC to perform the implementation of the decisions /goals of the C21 elements, 1-4...realistic fashion. Once the AMPs have been formed, the operational process of launching, mission implementation etc. is no longer keyed to the decision cycle

Biotemplated materials for sustainable energy and environment: current status and challenges.

PubMed

Zhou, Han; Fan, Tongxiang; Zhang, Di

2011-10-17

Materials science will play a key role in the further development of emerging solutions for the increasing problems of energy and environment. Materials found in nature have many inspiring structures, such as hierarchical organizations, periodic architectures, or nanostructures, that endow them with amazing functions, such as energy harvesting and conversion, antireflection, structural coloration, superhydrophobicity, and biological self-assembly. Biotemplating is an effective strategy to obtain morphology-controllable materials with structural specificity, complexity, and related unique functions. Herein, we highlight the synthesis and application of biotemplated materials for six key areas of energy and environment technologies, namely, photocatalytic hydrogen evolution, CO(2) reduction, solar cells, lithium-ion batteries, photocatalytic degradation, and gas/vapor sensing. Although the applications differ from each other, a common fundamental challenge is to realize optimum structures for improved performances. We highlight the role of four typical structures derived from biological systems exploited to optimize properties: hierarchical (porous) structures, periodic (porous) structures, hollow structures, and nanostructures. We also provide examples of using biogenic elements (e.g., C, Si, N, I, P, S) for the creation of active materials. Finally, we disscuss the challenges of achieving the desired performance for large-scale commercial applications and provide some useful prototypes from nature for the biomimetic design of new materials or systems. The emphasis is mainly focused on the structural effects and compositional utilization of biotemplated materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Dual Origin of the Xist Gene from a Protein-Coding Gene and a Set of Transposable Elements

PubMed Central

Elisaphenko, Eugeny A.; Kolesnikov, Nikolay N.; Shevchenko, Alexander I.; Rogozin, Igor B.; Nesterova, Tatyana B.; Brockdorff, Neil; Zakian, Suren M.

2008-01-01

X-chromosome inactivation, which occurs in female eutherian mammals is controlled by a complex X-linked locus termed the X-inactivation center (XIC). Previously it was proposed that genes of the XIC evolved, at least in part, as a result of pseudogenization of protein-coding genes. In this study we show that the key XIC gene Xist, which displays fragmentary homology to a protein-coding gene Lnx3, emerged de novo in early eutherians by integration of mobile elements which gave rise to simple tandem repeats. The Xist gene promoter region and four out of ten exons found in eutherians retain homology to exons of the Lnx3 gene. The remaining six Xist exons including those with simple tandem repeats detectable in their structure have similarity to different transposable elements. Integration of mobile elements into Xist accompanies the overall evolution of the gene and presumably continues in contemporary eutherian species. Additionally we showed that the combination of remnants of protein-coding sequences and mobile elements is not unique to the Xist gene and is found in other XIC genes producing non-coding nuclear RNA. PMID:18575625

Supervised Classification Processes for the Characterization of Heritage Elements, Case Study: Cuenca-Ecuador

NASA Astrophysics Data System (ADS)

Briones, J. C.; Heras, V.; Abril, C.; Sinchi, E.

2017-08-01

The proper control of built heritage entails many challenges related to the complexity of heritage elements and the extent of the area to be managed, for which the available resources must be efficiently used. In this scenario, the preventive conservation approach, based on the concept that prevent is better than cure, emerges as a strategy to avoid the progressive and imminent loss of monuments and heritage sites. Regular monitoring appears as a key tool to identify timely changes in heritage assets. This research demonstrates that the supervised learning model (Support Vector Machines - SVM) is an ideal tool that supports the monitoring process detecting visible elements in aerial images such as roofs structures, vegetation and pavements. The linear, gaussian and polynomial kernel functions were tested; the lineal function provided better results over the other functions. It is important to mention that due to the high level of segmentation generated by the classification procedure, it was necessary to apply a generalization process through opening a mathematical morphological operation, which simplified the over classification for the monitored elements.

Wrinkling reduction of membrane structure by trimming edges

NASA Astrophysics Data System (ADS)

Liu, Mingjun; Huang, Jin; Liu, Mingyue

2017-05-01

Thin membranes have negligible bending stiffness, compressive stresses inevitably lead to wrinkling. Therefore, it is important to keep the surface of membrane structures flat in order to guarantee high precision. Edge-trimming is an effective method to passively diminish wrinkles, however a key difficulty in this process is the determination of the optimal trimming level. In this paper, regular polygonal membrane structures subjected to equal radial forces were analyzed, and a new stress field distribution model for arc-edge square membrane structure was proposed to predict the optimal trimming level. This model is simple and applicable to any polygonal membrane structures. Comparison among the results of the finite element analysis, and the experimental and analytical results showed that the proposed model accurately described the stress field distribution and guaranteed that there are no wrinkles appear inside the effective inscribed circle region for the optimal trimming level.

GARN: Sampling RNA 3D Structure Space with Game Theory and Knowledge-Based Scoring Strategies.

PubMed

Boudard, Mélanie; Bernauer, Julie; Barth, Dominique; Cohen, Johanne; Denise, Alain

2015-01-01

Cellular processes involve large numbers of RNA molecules. The functions of these RNA molecules and their binding to molecular machines are highly dependent on their 3D structures. One of the key challenges in RNA structure prediction and modeling is predicting the spatial arrangement of the various structural elements of RNA. As RNA folding is generally hierarchical, methods involving coarse-grained models hold great promise for this purpose. We present here a novel coarse-grained method for sampling, based on game theory and knowledge-based potentials. This strategy, GARN (Game Algorithm for RNa sampling), is often much faster than previously described techniques and generates large sets of solutions closely resembling the native structure. GARN is thus a suitable starting point for the molecular modeling of large RNAs, particularly those with experimental constraints. GARN is available from: http://garn.lri.fr/.

Optimization of hierarchical structure and nanoscale-enabled plasmonic refraction for window electrodes in photovoltaics.

PubMed

Han, Bing; Peng, Qiang; Li, Ruopeng; Rong, Qikun; Ding, Yang; Akinoglu, Eser Metin; Wu, Xueyuan; Wang, Xin; Lu, Xubing; Wang, Qianming; Zhou, Guofu; Liu, Jun-Ming; Ren, Zhifeng; Giersig, Michael; Herczynski, Andrzej; Kempa, Krzysztof; Gao, Jinwei

2016-09-26

An ideal network window electrode for photovoltaic applications should provide an optimal surface coverage, a uniform current density into and/or from a substrate, and a minimum of the overall resistance for a given shading ratio. Here we show that metallic networks with quasi-fractal structure provides a near-perfect practical realization of such an ideal electrode. We find that a leaf venation network, which possesses key characteristics of the optimal structure, indeed outperforms other networks. We further show that elements of hierarchal topology, rather than details of the branching geometry, are of primary importance in optimizing the networks, and demonstrate this experimentally on five model artificial hierarchical networks of varied levels of complexity. In addition to these structural effects, networks containing nanowires are shown to acquire transparency exceeding the geometric constraint due to the plasmonic refraction.

Branchpoint expansion in a fully complementary three-way DNA junction.

PubMed

Sabir, Tara; Toulmin, Anita; Ma, Long; Jones, Anita C; McGlynn, Peter; Schröder, Gunnar F; Magennis, Steven W

2012-04-11

Branched nucleic acid molecules serve as key intermediates in DNA replication, recombination, and repair; architectural elements in RNA; and building blocks and functional components for nanoscience applications. Using a combination of high-resolution single-molecule FRET, time-resolved spectroscopy, and molecular modeling, we have probed the local and global structure of a DNA three-way junction (3WJ) in solution. We found that it adopts a Y-shaped, pyramidal structure, in which the bases adjacent to the branchpoint are unpaired, despite the full Watson-Crick complementarity of the molecule. The unpairing allows a nanoscale cavity to form at the junction center. Our structure accounts for earlier observations made of the structure, flexibility, and reactivity of 3WJs. We anticipate that these results will guide the development of new DNA-based supramolecular receptors and nanosystems. © 2012 American Chemical Society

Parental and youth understanding of the informed consent process for pediatric endoscopy.

PubMed

Jubbal, Kevin; Chun, Stanford; Chang, Jeremy; Zhang, Sherry; Terrones, Laura; Huang, Jeannie S

2015-06-01

Informed consent (IC) is an essential communication between patient/representative and physician that acknowledges patient autonomy; assent is the equivalent process performed between youth and physician. For clinical procedures involving youth, only the IC process between guardian/parent and physician is required to be performed. Nevertheless, experts recommend that youth undergo assent whenever possible. In the present study, we explored both parental and youth understanding of required IC elements in IC discussions before pediatric endoscopy. Following signing of IC documents on the day of endoscopy at a tertiary care academic medical center, youth and their parents underwent structured interviews to assess comprehension of key elements of the IC process. A total of 88 children and adolescents and their parents were evaluated. Two youth and 12 parents demonstrated comprehensive understanding of key IC elements for pediatric endoscopy. Suboptimal youth understanding was demonstrated for nature of the procedure (25% with adequate understanding) and related risks (17%), and alternatives (14%) to the procedure. Suboptimal parental understanding was demonstrated for procedure alternatives (24%). Youth overall understanding of IC varied by age, whereas parental global understanding of IC varied by physician. Understanding of IC performed for pediatric endoscopy could be improved in both parents and youth. Our findings suggest that interventions targeting parents, youth, and physicians may be helpful. Further study is needed to determine whether our findings are representative of IC understanding at other pediatric endoscopy centers.

Subject-specific finite element modelling of the human foot complex during walking: sensitivity analysis of material properties, boundary and loading conditions.

PubMed

Akrami, Mohammad; Qian, Zhihui; Zou, Zhemin; Howard, David; Nester, Chris J; Ren, Lei

2018-04-01

The objective of this study was to develop and validate a subject-specific framework for modelling the human foot. This was achieved by integrating medical image-based finite element modelling, individualised multi-body musculoskeletal modelling and 3D gait measurements. A 3D ankle-foot finite element model comprising all major foot structures was constructed based on MRI of one individual. A multi-body musculoskeletal model and 3D gait measurements for the same subject were used to define loading and boundary conditions. Sensitivity analyses were used to investigate the effects of key modelling parameters on model predictions. Prediction errors of average and peak plantar pressures were below 10% in all ten plantar regions at five key gait events with only one exception (lateral heel, in early stance, error of 14.44%). The sensitivity analyses results suggest that predictions of peak plantar pressures are moderately sensitive to material properties, ground reaction forces and muscle forces, and significantly sensitive to foot orientation. The maximum region-specific percentage change ratios (peak stress percentage change over parameter percentage change) were 1.935-2.258 for ground reaction forces, 1.528-2.727 for plantar flexor muscles and 4.84-11.37 for foot orientations. This strongly suggests that loading and boundary conditions need to be very carefully defined based on personalised measurement data.

Trace Elemental Imaging of Rare Earth Elements Discriminates Tissues at Microscale in Flat Fossils

PubMed Central

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809

Trace elemental imaging of rare earth elements discriminates tissues at microscale in flat fossils.

PubMed

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B; Cohen, Serge X; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies.

Identification of a key structural element for protein folding within beta-hairpin turns.

PubMed

Kim, Jaewon; Brych, Stephen R; Lee, Jihun; Logan, Timothy M; Blaber, Michael

2003-05-09

Specific residues in a polypeptide may be key contributors to the stability and foldability of the unique native structure. Identification and prediction of such residues is, therefore, an important area of investigation in solving the protein folding problem. Atypical main-chain conformations can help identify strains within a folded protein, and by inference, positions where unique amino acids may have a naturally high frequency of occurrence due to favorable contributions to stability and folding. Non-Gly residues located near the left-handed alpha-helical region (L-alpha) of the Ramachandran plot are a potential indicator of structural strain. Although many investigators have studied mutations at such positions, no consistent energetic or kinetic contributions to stability or folding have been elucidated. Here we report a study of the effects of Gly, Ala and Asn substitutions found within the L-alpha region at a characteristic position in defined beta-hairpin turns within human acidic fibroblast growth factor, and demonstrate consistent effects upon stability and folding kinetics. The thermodynamic and kinetic data are compared to available data for similar mutations in other proteins, with excellent agreement. The results have identified that Gly at the i+3 position within a subset of beta-hairpin turns is a key contributor towards increasing the rate of folding to the native state of the polypeptide while leaving the rate of unfolding largely unchanged.

The Metabolic Core and Catalytic Switches Are Fundamental Elements in the Self-Regulation of the Systemic Metabolic Structure of Cells

PubMed Central

De la Fuente, Ildefonso M.; Cortes, Jesus M.; Perez-Pinilla, Martin B.; Ruiz-Rodriguez, Vicente; Veguillas, Juan

2011-01-01

Background Experimental observations and numerical studies with dissipative metabolic networks have shown that cellular enzymatic activity self-organizes spontaneously leading to the emergence of a metabolic core formed by a set of enzymatic reactions which are always active under all environmental conditions, while the rest of catalytic processes are only intermittently active. The reactions of the metabolic core are essential for biomass formation and to assure optimal metabolic performance. The on-off catalytic reactions and the metabolic core are essential elements of a Systemic Metabolic Structure which seems to be a key feature common to all cellular organisms. Methodology/Principal Findings In order to investigate the functional importance of the metabolic core we have studied different catalytic patterns of a dissipative metabolic network under different external conditions. The emerging biochemical data have been analysed using information-based dynamic tools, such as Pearson's correlation and Transfer Entropy (which measures effective functionality). Our results show that a functional structure of effective connectivity emerges which is dynamical and characterized by significant variations of bio-molecular information flows. Conclusions/Significance We have quantified essential aspects of the metabolic core functionality. The always active enzymatic reactions form a hub –with a high degree of effective connectivity- exhibiting a wide range of functional information values being able to act either as a source or as a sink of bio-molecular causal interactions. Likewise, we have found that the metabolic core is an essential part of an emergent functional structure characterized by catalytic modules and metabolic switches which allow critical transitions in enzymatic activity. Both, the metabolic core and the catalytic switches in which also intermittently-active enzymes are involved seem to be fundamental elements in the self-regulation of the Systemic Metabolic Structure. PMID:22125607

AIDS and HIV Training and Education in Criminal Justice Agencies. AIDS Bulletin.

ERIC Educational Resources Information Center

Hammett, Theodore M.

This bulletin summarizes key elements of an effective AIDS training and education program for law enforcement and corrections personnel. First, these key elements of training and education for criminal justice personnel are discussed: staff participation in materials development; timely and frequent training; mandatory training; live training by…

The Use of the STAGS Finite Element Code in Stitched Structures Development

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Lovejoy, Andrew E.

2014-01-01

In the last 30 years NASA has worked in collaboration with industry to develop enabling technologies needed to make aircraft more fuel-efficient and more affordable. The focus on the airframe has been to reduce weight, improve damage tolerance and better understand structural behavior under realistic flight and ground loading conditions. Stitched structure is a technology that can address the weight savings, cost reduction, and damage tolerance goals, but only if it is supported by accurate analytical techniques. Development of stitched technology began in the 1990's as a partnership between NASA and Boeing (McDonnell Douglas at the time) under the Advanced Composites Technology Program and has continued under various titles and programs and into the Environmentally Responsible Aviation Project today. These programs contained development efforts involving manufacturing development, design, detailed analysis, and testing. Each phase of development, from coupons to large aircraft components was supported by detailed analysis to prove that the behavior of these structures was well-understood and predictable. The Structural Analysis of General Shells (STAGS) computer code was a critical tool used in the development of many stitched structures. As a key developer of STAGS, Charles Rankin's contribution to the programs was quite significant. Key features of STAGS used in these analyses and discussed in this paper include its accurate nonlinear and post-buckling capabilities, its ability to predict damage growth, and the use of Lagrange constraints and follower forces.

Monitoring of Concrete Structures Using Ofdr Technique

NASA Astrophysics Data System (ADS)

Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

2011-06-01

Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

Fluid-structure coupling for wind turbine blade analysis using OpenFOAM

NASA Astrophysics Data System (ADS)

Dose, Bastian; Herraez, Ivan; Peinke, Joachim

2015-11-01

Modern wind turbine rotor blades are designed increasingly large and flexible. This structural flexibility represents a problem for the field of Computational Fluid Dynamics (CFD), which is used for accurate load calculations and detailed investigations of rotor aerodynamics. As the blade geometries within CFD simulations are considered stiff, the effect of blade deformation caused by aerodynamic loads cannot be captured by the common CFD approach. Coupling the flow solver with a structural solver can overcome this restriction and enables the investigation of flexible wind turbine blades. For this purpose, a new Finite Element (FE) solver was implemented into the open source CFD code OpenFOAM. Using a beam element formulation based on the Geometrically Exact Beam Theory (GEBT), the structural model can capture geometric non-linearities such as large deformations. Coupled with CFD solvers of the OpenFOAM package, the new framework represents a powerful tool for aerodynamic investigations. In this work, we investigated the aerodynamic performance of a state of the art wind turbine. For different wind speeds, aerodynamic key parameters are evaluated and compared for both, rigid and flexible blade geometries. The present work is funded within the framework of the joint project Smart Blades (0325601D) by the German Federal Ministry for Economic Affairs and Energy (BMWi) under decision of the German Federal Parliament.

A review of international pharmacy-based minor ailment services and proposed service design model.

PubMed

Aly, Mariyam; García-Cárdenas, Victoria; Williams, Kylie; Benrimoj, Shalom I

2018-01-05

The need to consider sustainable healthcare solutions is essential. An innovative strategy used to promote minor ailment care is the utilisation of community pharmacists to deliver minor ailment services (MASs). Promoting higher levels of self-care can potentially reduce the strain on existing resources. To explore the features of international MASs, including their similarities and differences, and consider the essential elements to design a MAS model. A grey literature search strategy was completed in June 2017 to comply with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses standard. This included (1) Google/Yahoo! search engines, (2) targeted websites, and (3) contact with commissioning organisations. Executive summaries, table of contents and title pages of documents were reviewed. Key characteristics of MASs were extracted and a MAS model was developed. A total of 147 publications were included in the review. Key service elements identified included eligibility, accessibility, staff involvement, reimbursement systems. Several factors need to be considered when designing a MAS model; including contextualisation of MAS to the market. Stakeholder engagement, service planning, governance, implementation and review have emerged as key aspects involved with a design model. MASs differ in their structural parameters. Consideration of these parameters is necessary when devising MAS aims and assessing outcomes to promote sustainability and success of the service. Copyright © 2018 Elsevier Inc. All rights reserved.

Recent progress in the structure control of Pd–Ru bimetallic nanomaterials

PubMed Central

Wu, Dongshuang; Kusada, Kohei; Kitagawa, Hiroshi

2016-01-01

Abstract Pd and Ru are two key elements of the platinum-group metals that are invaluable to areas such as catalysis and energy storage/transfer. To maximize the potential of the Pd and Ru elements, significant effort has been devoted to synthesizing Pd–Ru bimetallic materials. However, most of the reports dealing with this subject describe phase-separated structures such as near-surface alloys and physical mixtures of monometallic nanoparticles (NPs). Pd–Ru alloys with homogenous structure and arbitrary metallic ratio are highly desired for basic scientific research and commercial material design. In the past several years, with the development of nanoscience, Pd–Ru bimetallic alloys with different architectures including heterostructure, core-shell structure and solid-solution alloy were successfully synthesized. In particular, we have now reached the stage of being able to obtain Pd–Ru solid-solution alloy NPs over the whole composition range. These Pd–Ru bimetallic alloys are better catalysts than their parent metal NPs in many catalytic reactions, because the electronic structures of Pd and Ru are modified by alloying. In this review, we describe the recent development in the structure control of Pd–Ru bimetallic nanomaterials. Aiming for a better understanding of the synthesis strategies, some fundamental details including fabrication methods and formation mechanisms are discussed. We stress that the modification of electronic structure, originating from different nanoscale geometry and chemical composition, profoundly affects material properties. Finally, we discuss open issues in this field. PMID:27877905

[Effects of functional interactions between nonhomologous insulators Wari and Su(Hw)].

PubMed

Erokhin, M M; Georgiev, P G; Chetverina, D A

2010-01-01

Insulators are regulatory DNA elements restricting gene activation by enhancers. Interactions between insulators can lead to both insulation and activation of promoters by enhancers. In this work, we analyzed the effects of interaction of two Drosophila insulators, Wari and Su(Hw). The functional interaction between these insulators was found to enhance the activity of the Su(Hw) insulator only, but not of the Wari insulator. This suggests that the formation of a chromatin loop between interacting insulators is not a key factor for enhancement of insulation, which is in disagreement with the main idea of structural models. In addition, the effect of interaction between Wari and Su(Hw) depends on a distance between them and on the position in the system relative to other regulatory elements.

KSC-06pd2287

NASA Image and Video Library

2006-10-12

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is transferred from the checkout cell for attaching to its twin solid rocket boosters on the mobile launch platform in highbay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6-feet wide and 154-feet tall. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6-feet wide and 154-feet tall. STS-116 will be mission no. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

Functionally relevant protein motions: Extracting basin-specific collective coordinates from molecular dynamics trajectories

NASA Astrophysics Data System (ADS)

Pan, Patricia Wang; Dickson, Russell J.; Gordon, Heather L.; Rothstein, Stuart M.; Tanaka, Shigenori

2005-01-01

Functionally relevant motion of proteins has been associated with a number of atoms moving in a concerted fashion along so-called "collective coordinates." We present an approach to extract collective coordinates from conformations obtained from molecular dynamics simulations. The power of this technique for differentiating local structural fuctuations between classes of conformers obtained by clustering is illustrated by analyzing nanosecond-long trajectories for the response regulator protein Spo0F of Bacillus subtilis, generated both in vacuo and using an implicit-solvent representation. Conformational clustering is performed using automated histogram filtering of the inter-Cα distances. Orthogonal (varimax) rotation of the vectors obtained by principal component analysis of these interresidue distances for the members of individual clusters is key to the interpretation of collective coordinates dominating each conformational class. The rotated loadings plots isolate significant variation in interresidue distances, and these are associated with entire mobile secondary structure elements. From this we infer concerted motions of these structural elements. For the Spo0F simulations employing an implicit-solvent representation, collective coordinates obtained in this fashion are consistent with the location of the protein's known active sites and experimentally determined mobile regions.

Design sensitivity analysis of rotorcraft airframe structures for vibration reduction

NASA Technical Reports Server (NTRS)

Murthy, T. Sreekanta

1987-01-01

Optimization of rotorcraft structures for vibration reduction was studied. The objective of this study is to develop practical computational procedures for structural optimization of airframes subject to steady-state vibration response constraints. One of the key elements of any such computational procedure is design sensitivity analysis. A method for design sensitivity analysis of airframes under vibration response constraints is presented. The mathematical formulation of the method and its implementation as a new solution sequence in MSC/NASTRAN are described. The results of the application of the method to a simple finite element stick model of the AH-1G helicopter airframe are presented and discussed. Selection of design variables that are most likely to bring about changes in the response at specified locations in the airframe is based on consideration of forced response strain energy. Sensitivity coefficients are determined for the selected design variable set. Constraints on the natural frequencies are also included in addition to the constraints on the steady-state response. Sensitivity coefficients for these constraints are determined. Results of the analysis and insights gained in applying the method to the airframe model are discussed. The general nature of future work to be conducted is described.

An Efficient and Versatile Means for Assembling and Manufacturing Systems in Space

NASA Technical Reports Server (NTRS)

Dorsey, John T.; Doggett, William R.; Hafley, Robert A.; Komendera, Erik; Correll, Nikolaus; King, Bruce

2012-01-01

Within NASA Space Science, Exploration and the Office of Chief Technologist, there are Grand Challenges and advanced future exploration, science and commercial mission applications that could benefit significantly from large-span and large-area structural systems. Of particular and persistent interest to the Space Science community is the desire for large (in the 10- 50 meter range for main aperture diameter) space telescopes that would revolutionize space astronomy. Achieving these systems will likely require on-orbit assembly, but previous approaches for assembling large-scale telescope truss structures and systems in space have been perceived as very costly because they require high precision and custom components. These components rely on a large number of mechanical connections and supporting infrastructure that are unique to each application. In this paper, a new assembly paradigm that mitigates these concerns is proposed and described. A new assembly approach, developed to implement the paradigm, is developed incorporating: Intelligent Precision Jigging Robots, Electron-Beam welding, robotic handling/manipulation, operations assembly sequence and path planning, and low precision weldable structural elements. Key advantages of the new assembly paradigm, as well as concept descriptions and ongoing research and technology development efforts for each of the major elements are summarized.

A domains-based taxonomy of supported accommodation for people with severe and persistent mental illness.

PubMed

Siskind, Dan; Harris, Meredith; Pirkis, Jane; Whiteford, Harvey

2013-06-01

A lack of definitional clarity in supported accommodation and the absence of a widely accepted system for classifying supported accommodation models creates barriers to service planning and evaluation. We undertook a systematic review of existing supported accommodation classification systems. Using a structured system for qualitative data analysis, we reviewed the stratification features in these classification systems, identified the key elements of supported accommodation and arranged them into domains and dimensions to create a new taxonomy. The existing classification systems were mapped onto the new taxonomy to verify the domains and dimensions. Existing classification systems used either a service-level characteristic or programmatic approach. We proposed a taxonomy based around four domains: duration of tenure; patient characteristics; housing characteristics; and service characteristics. All of the domains in the taxonomy were drawn from the existing classification structures; however, none of the existing classification structures covered all of the domains in the taxonomy. Existing classification systems are regionally based, limited in scope and lack flexibility. A domains-based taxonomy can allow more accurate description of supported accommodation services, aid in identifying the service elements likely to improve outcomes for specific patient populations, and assist in service planning.

NASA Integrated Model Centric Architecture (NIMA) Model Use and Re-Use

NASA Technical Reports Server (NTRS)

Conroy, Mike; Mazzone, Rebecca; Lin, Wei

2012-01-01

This whitepaper accepts the goals, needs and objectives of NASA's Integrated Model-centric Architecture (NIMA); adds experience and expertise from the Constellation program as well as NASA's architecture development efforts; and provides suggested concepts, practices and norms that nurture and enable model use and re-use across programs, projects and other complex endeavors. Key components include the ability to effectively move relevant information through a large community, process patterns that support model reuse and the identification of the necessary meta-information (ex. history, credibility, and provenance) to safely use and re-use that information. In order to successfully Use and Re-Use Models and Simulations we must define and meet key organizational and structural needs: 1. We must understand and acknowledge all the roles and players involved from the initial need identification through to the final product, as well as how they change across the lifecycle. 2. We must create the necessary structural elements to store and share NIMA-enabled information throughout the Program or Project lifecycle. 3. We must create the necessary organizational processes to stand up and execute a NIMA-enabled Program or Project throughout its lifecycle. NASA must meet all three of these needs to successfully use and re-use models. The ability to Reuse Models a key component of NIMA and the capabilities inherent in NIMA are key to accomplishing NASA's space exploration goals. 11

Design of a Nanoscale, CMOS-Integrable, Thermal-Guiding Structure for Boolean-Logic and Neuromorphic Computation.

PubMed

Loke, Desmond; Skelton, Jonathan M; Chong, Tow-Chong; Elliott, Stephen R

2016-12-21

One of the requirements for achieving faster CMOS electronics is to mitigate the unacceptably large chip areas required to steer heat away from or, more recently, toward the critical nodes of state-of-the-art devices. Thermal-guiding (TG) structures can efficiently direct heat by "meta-materials" engineering; however, some key aspects of the behavior of these systems are not fully understood. Here, we demonstrate control of the thermal-diffusion properties of TG structures by using nanometer-scale, CMOS-integrable, graphene-on-silica stacked materials through finite-element-methods simulations. It has been shown that it is possible to implement novel, controllable, thermally based Boolean-logic and spike-timing-dependent plasticity operations for advanced (neuromorphic) computing applications using such thermal-guide architectures.

Symmetries of hyper-Kähler (or Poisson gauge field) hierarchy

NASA Astrophysics Data System (ADS)

Takasaki, K.

1990-08-01

Symmetry properties of the space of complex (or formal) hyper-Kähler metrics are studied in the language of hyper-Kähler hierarchies. The construction of finite symmetries is analogous to the theory of Riemann-Hilbert transformations, loop group elements now taking values in a (pseudo-) group of canonical transformations of a simplectic manifold. In spite of their highly nonlinear and involved nature, infinitesimal expressions of these symmetries are shown to have a rather simple form. These infinitesimal transformations are extended to the Plebanski key functions to give rise to a nonlinear realization of a Poisson loop algebra. The Poisson algebra structure turns out to originate in a contact structure behind a set of symplectic structures inherent in the hyper-Kähler hierarchy. Possible relations to membrane theory are briefly discussed.

Center for Computational Structures Technology

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Perry, Ferman W.

1995-01-01

The Center for Computational Structures Technology (CST) is intended to serve as a focal point for the diverse CST research activities. The CST activities include the use of numerical simulation and artificial intelligence methods in modeling, analysis, sensitivity studies, and optimization of flight-vehicle structures. The Center is located at NASA Langley and is an integral part of the School of Engineering and Applied Science of the University of Virginia. The key elements of the Center are: (1) conducting innovative research on advanced topics of CST; (2) acting as pathfinder by demonstrating to the research community what can be done (high-potential, high-risk research); (3) strong collaboration with NASA scientists and researchers from universities and other government laboratories; and (4) rapid dissemination of CST to industry, through integration of industrial personnel into the ongoing research efforts.

GLYDE-II: The GLYcan data exchange format

PubMed Central

Ranzinger, Rene; Kochut, Krys J.; Miller, John A.; Eavenson, Matthew; Lütteke, Thomas; York, William S.

2017-01-01

Summary The GLYcan Data Exchange (GLYDE) standard has been developed for the representation of the chemical structures of monosaccharides, glycans and glycoconjugates using a connection table formalism formatted in XML. This format allows structures, including those that do not exist in any database, to be unambiguously represented and shared by diverse computational tools. GLYDE implements a partonomy model based on human language along with rules that provide consistent structural representations, including a robust namespace for specifying monosaccharides. This approach facilitates the reuse of data processing software at the level of granularity that is most appropriate for extraction of the desired information. GLYDE-II has already been used as a key element of several glycoinformatics tools. The philosophical and technical underpinnings of GLYDE-II and recent implementation of its enhanced features are described. PMID:28955652

Geologic cross section C-C' through the Appalachian basin from Erie County, north-central Ohio, to the Valley and Ridge province, Bedford County, south-central Pennsylvania

USGS Publications Warehouse

Ryder, Robert T.; Trippi, Michael H.; Swezey, Christopher S.; Crangle, Robert D.; Hope, Rebecca S.; Rowan, Elisabeth L.; Lentz, Erika E.

2012-01-01

Geologic cross section C-C' is the third in a series of cross sections constructed by the U.S. Geological Survey (USGS) to document and improve understanding of the geologic framework and petroleum systems of the Appalachian basin. Cross section C-C' provides a regional view of the structural and stratigraphic framework of the Appalachian basin from north-central Ohio to the Valley and Ridge province in south-central Pennsylvania, a distance of approximately 260 miles (mi). This cross section is a companion to cross sections E-E' and D-D' that are located about 50 to 125 mi and 25 to 50 mi, respectively, to the southwest. Cross section C-C' contains much information that is useful for evaluating energy resources in the Appalachian basin. Although specific petroleum systems are not identified on the cross section, many of their key elements (such as source rocks, reservoir rocks, seals, and traps) can be inferred from lithologic units, unconformities, and geologic structures shown on the cross section. Other aspects of petroleum systems (such as the timing of petroleum generation and preferred migration pathways) may be evaluated by burial history, thermal history, and fluid flow models based on what is shown on the cross section. Cross section C-C' also provides a general framework (stratigraphic units and general rock types) for the coal-bearing section, although the cross section lacks the detail to illustrate key elements of coal systems (such as paleoclimate, coal quality, and coal rank). In addition, cross section C-C' may be used as a reconnaissance tool to identify plausible geologic structures and strata for the subsurface storage of liquid waste or for the sequestration of carbon dioxide.

KSC01pp0017

NASA Image and Video Library

2001-01-03

KENNEDY SPACE CENTER, Fla. -- Space Shuttle Atlantis reaches its destination, Launch Pad 39A, for liftoff no earlier than Jan. 19 on mission STS-98. To its immediate left is the Fixed Service Structure, with its 80-foot-tall white lighting mast on top. Further to the left is the Rotating Service Structure, where the white payload canister is being lifted to the Payload Changeout Room. The payload for the mission is the U.S. Lab Destiny, a key element in the construction of the International Space Station. The lab has five system racks for experiments already installed inside the module. After delivery of electronics in the lab, electrically powered attitude control for Control Moment Gyroscopes will be activated

Static and Dynamic Model Update of an Inflatable/Rigidizable Torus Structure

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Reaves, mercedes C.

2006-01-01

The present work addresses the development of an experimental and computational procedure for validating finite element models. A torus structure, part of an inflatable/rigidizable Hexapod, is used to demonstrate the approach. Because of fabrication, materials, and geometric uncertainties, a statistical approach combined with optimization is used to modify key model parameters. Static test results are used to update stiffness parameters and dynamic test results are used to update the mass distribution. Updated parameters are computed using gradient and non-gradient based optimization algorithms. Results show significant improvements in model predictions after parameters are updated. Lessons learned in the areas of test procedures, modeling approaches, and uncertainties quantification are presented.

Neurocircuitry of Addiction

PubMed Central

Koob, George F; Volkow, Nora D

2010-01-01

Drug addiction is a chronically relapsing disorder that has been characterized by (1) compulsion to seek and take the drug, (2) loss of control in limiting intake, and (3) emergence of a negative emotional state (eg, dysphoria, anxiety, irritability) reflecting a motivational withdrawal syndrome when access to the drug is prevented. Drug addiction has been conceptualized as a disorder that involves elements of both impulsivity and compulsivity that yield a composite addiction cycle composed of three stages: ‘binge/intoxication', ‘withdrawal/negative affect', and ‘preoccupation/anticipation' (craving). Animal and human imaging studies have revealed discrete circuits that mediate the three stages of the addiction cycle with key elements of the ventral tegmental area and ventral striatum as a focal point for the binge/intoxication stage, a key role for the extended amygdala in the withdrawal/negative affect stage, and a key role in the preoccupation/anticipation stage for a widely distributed network involving the orbitofrontal cortex–dorsal striatum, prefrontal cortex, basolateral amygdala, hippocampus, and insula involved in craving and the cingulate gyrus, dorsolateral prefrontal, and inferior frontal cortices in disrupted inhibitory control. The transition to addiction involves neuroplasticity in all of these structures that may begin with changes in the mesolimbic dopamine system and a cascade of neuroadaptations from the ventral striatum to dorsal striatum and orbitofrontal cortex and eventually dysregulation of the prefrontal cortex, cingulate gyrus, and extended amygdala. The delineation of the neurocircuitry of the evolving stages of the addiction syndrome forms a heuristic basis for the search for the molecular, genetic, and neuropharmacological neuroadaptations that are key to vulnerability for developing and maintaining addiction. PMID:19710631

An Inverse Interpolation Method Utilizing In-Flight Strain Measurements for Determining Loads and Structural Response of Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Shkarayev, S.; Krashantisa, R.; Tessler, A.

2004-01-01

An important and challenging technology aimed at the next generation of aerospace vehicles is that of structural health monitoring. The key problem is to determine accurately, reliably, and in real time the applied loads, stresses, and displacements experienced in flight, with such data establishing an information database for structural health monitoring. The present effort is aimed at developing a finite element-based methodology involving an inverse formulation that employs measured surface strains to recover the applied loads, stresses, and displacements in an aerospace vehicle in real time. The computational procedure uses a standard finite element model (i.e., "direct analysis") of a given airframe, with the subsequent application of the inverse interpolation approach. The inverse interpolation formulation is based on a parametric approximation of the loading and is further constructed through a least-squares minimization of calculated and measured strains. This procedure results in the governing system of linear algebraic equations, providing the unknown coefficients that accurately define the load approximation. Numerical simulations are carried out for problems involving various levels of structural approximation. These include plate-loading examples and an aircraft wing box. Accuracy and computational efficiency of the proposed method are discussed in detail. The experimental validation of the methodology by way of structural testing of an aircraft wing is also discussed.

Structural Basis For Antigenic Peptide Precursor Processing by the Endoplasmic Reticulum Aminopeptidase ERAP1

DOE Office of Scientific and Technical Information (OSTI.GOV)

T Nguyen; S Chang; I Evnouchidou

2011-12-31

ERAP1 trims antigen precursors to fit into MHC class I proteins. To fulfill this function, ERAP1 has unique substrate preferences, trimming long peptides but sparing shorter ones. To identify the structural basis for ERAP1's unusual properties, we determined the X-ray crystal structure of human ERAP1 bound to bestatin. The structure reveals an open conformation with a large interior compartment. An extended groove originating from the enzyme's catalytic center can accommodate long peptides and has features that explain ERAP1's broad specificity for antigenic peptide precursors. Structural and biochemical analyses suggest a mechanism for ERAP1's length-dependent trimming activity, whereby binding of longmore » rather than short substrates induces a conformational change with reorientation of a key catalytic residue toward the active site. ERAP1's unique structural elements suggest how a generic aminopeptidase structure has been adapted for the specialized function of trimming antigenic precursors.« less

Multidisciplinary optimization of controlled space structures with global sensitivity equations

NASA Technical Reports Server (NTRS)

Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.

1991-01-01

A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.

Chain-like structure elements in Ni40Ta60 metallic glasses observed by scanning tunneling microscopy

PubMed Central

Pawlak, Rémy; Marot, Laurent; Sadeghi, Ali; Kawai, Shigeki; Glatzel, Thilo; Reimann, Peter; Goedecker, Stefan; Güntherodt, Hans-Joachim; Meyer, Ernst

2015-01-01

The structure of metallic glasses is a long-standing question because the lack of long-range order makes diffraction based techniques difficult to be applied. Here, we used scanning tunneling microscopy with large tunneling resistance of 6 GΩ at low temperature in order to minimize forces between probe and sample and reduce thermal fluctuations of metastable structures. Under these extremely gentle conditions, atomic structures of Ni40Ta60 metallic glasses are revealed with unprecedented lateral resolution. In agreement with previous models and experiments, icosahedral-like clusters are observed. The clusters show a high degree of mobility, which explains the need of low temperatures for stable imaging. In addition to icosahedrons, chain-like structures are resolved and comparative density functional theory (DFT) calculations confirm that these structures are meta-stable. The co-existence of icosahedral and chain-like structures might be an key ingredient for the understanding of the mechanical properties of metallic glasses. PMID:26268430

Variable stiffness sandwich panels using electrostatic interlocking core

NASA Astrophysics Data System (ADS)

Heath, Callum J. C.; Bond, Ian P.; Potter, Kevin D.

2016-04-01

Structural topology has a large impact on the flexural stiffness of a beam structure. Reversible attachment between discrete substructures allows for control of shear stress transfer between structural elements, thus stiffness modulation. Electrostatic adhesion has shown promise for providing a reversible latching mechanism for controllable internal connectivity. Building on previous research, a thin film copper polyimide laminate has been used to incorporate high voltage electrodes to Fibre Reinforced Polymer (FRP) sandwich structures. The level of electrostatic holding force across the electrode interface is key to the achievable level of stiffness modulation. The use of non-flat interlocking core structures can allow for a significant increase in electrode contact area for a given core geometry, thus a greater electrostatic holding force. Interlocking core geometries based on cosine waves can be Computer Numerical Control (CNC) machined from Rohacell IGF 110 Foam core. These Interlocking Core structures could allow for enhanced variable stiffness functionality compared to basic planar electrodes. This novel concept could open up potential new applications for electrostatically induced variable stiffness structures.

The Green House Model of Nursing Home Care in Design and Implementation.

PubMed

Cohen, Lauren W; Zimmerman, Sheryl; Reed, David; Brown, Patrick; Bowers, Barbara J; Nolet, Kimberly; Hudak, Sandra; Horn, Susan

2016-02-01

To describe the Green House (GH) model of nursing home (NH) care, and examine how GH homes vary from the model, one another, and their founding (or legacy) NH. Data include primary quantitative and qualitative data and secondary quantitative data, derived from 12 GH/legacy NH organizations February 2012-September 2014. This mixed methods, cross-sectional study used structured interviews to obtain information about presence of, and variation in, GH-relevant structures and processes of care. Qualitative questions explored reasons for variation in model implementation. Interview data were analyzed using related-sample tests, and qualitative data were iteratively analyzed using a directed content approach. GH homes showed substantial variation in practices to support resident choice and decision making; neither GH nor legacy homes provided complete choice, and all GH homes excluded residents from some key decisions. GH homes were most consistent with the model and one another in elements to create a real home, such as private rooms and baths and open kitchens, and in staff-related elements, such as self-managed work teams and consistent, universal workers. Although variation in model implementation complicates evaluation, if expansion is to continue, it is essential to examine GH elements and their outcomes. © Health Research and Educational Trust.

A novel metadata management model to capture consent for record linkage in longitudinal research studies.

PubMed

McMahon, Christiana; Denaxas, Spiros

2017-11-06

Informed consent is an important feature of longitudinal research studies as it enables the linking of the baseline participant information with administrative data. The lack of standardized models to capture consent elements can lead to substantial challenges. A structured approach to capturing consent-related metadata can address these. a) Explore the state-of-the-art for recording consent; b) Identify key elements of consent required for record linkage; and c) Create and evaluate a novel metadata management model to capture consent-related metadata. The main methodological components of our work were: a) a systematic literature review and qualitative analysis of consent forms; b) the development and evaluation of a novel metadata model. We qualitatively analyzed 61 manuscripts and 30 consent forms. We extracted data elements related to obtaining consent for linkage. We created a novel metadata management model for consent and evaluated it by comparison with the existing standards and by iteratively applying it to case studies. The developed model can facilitate the standardized recording of consent for linkage in longitudinal research studies and enable the linkage of external participant data. Furthermore, it can provide a structured way of recording consent-related metadata and facilitate the harmonization and streamlining of processes.

α-Helical element at the hormone-binding surface of the insulin receptor functions as a signaling element to activate its tyrosine kinase

PubMed Central

Whittaker, Jonathan; Whittaker, Linda J.; Roberts, Charles T.; Phillips, Nelson B.; Ismail-Beigi, Faramarz; Lawrence, Michael C.; Weiss, Michael A.

2012-01-01

The primary hormone-binding surface of the insulin receptor spans one face of the N-terminal β-helix of the α-subunit (the L1 domain) and an α-helix in its C-terminal segment (αCT). Crystallographic analysis of the free ectodomain has defined a contiguous dimer-related motif in which the αCT α-helix packs against L1 β-strands 2 and 3. To relate structure to function, we exploited expanded genetic-code technology to insert photo-activatable probes at key sites in L1 and αCT. The pattern of αCT-mediated photo–cross-linking within the free and bound receptor is in accord with the crystal structure and prior mutagenesis. Surprisingly, L1 photo-probes in β-strands 2 and 3, predicted to be shielded by αCT, efficiently cross-link to insulin. Furthermore, anomalous mutations were identified on neighboring surfaces of αCT and insulin that impair hormone-dependent activation of the intracellular receptor tyrosine kinase (contained within the transmembrane β-subunit) disproportionately to their effects on insulin binding. Taken together, these results suggest that αCT, in addition to its hormone-recognition role, provides a signaling element in the mechanism of receptor activation. PMID:22736795

α-Helical element at the hormone-binding surface of the insulin receptor functions as a signaling element to activate its tyrosine kinase.

PubMed

Whittaker, Jonathan; Whittaker, Linda J; Roberts, Charles T; Phillips, Nelson B; Ismail-Beigi, Faramarz; Lawrence, Michael C; Weiss, Michael A

2012-07-10

The primary hormone-binding surface of the insulin receptor spans one face of the N-terminal β-helix of the α-subunit (the L1 domain) and an α-helix in its C-terminal segment (αCT). Crystallographic analysis of the free ectodomain has defined a contiguous dimer-related motif in which the αCT α-helix packs against L1 β-strands 2 and 3. To relate structure to function, we exploited expanded genetic-code technology to insert photo-activatable probes at key sites in L1 and αCT. The pattern of αCT-mediated photo-cross-linking within the free and bound receptor is in accord with the crystal structure and prior mutagenesis. Surprisingly, L1 photo-probes in β-strands 2 and 3, predicted to be shielded by αCT, efficiently cross-link to insulin. Furthermore, anomalous mutations were identified on neighboring surfaces of αCT and insulin that impair hormone-dependent activation of the intracellular receptor tyrosine kinase (contained within the transmembrane β-subunit) disproportionately to their effects on insulin binding. Taken together, these results suggest that αCT, in addition to its hormone-recognition role, provides a signaling element in the mechanism of receptor activation.

Are electronic health records ready for genomic medicine?

PubMed

Scheuner, Maren T; de Vries, Han; Kim, Benjamin; Meili, Robin C; Olmstead, Sarah H; Teleki, Stephanie

2009-07-01

The goal of this project was to assess genetic/genomic content in electronic health records. Semistructured interviews were conducted with key informants. Questions addressed documentation, organization, display, decision support and security of family history and genetic test information, and challenges and opportunities relating to integrating genetic/genomics content in electronic health records. There were 56 participants: 10 electronic health record specialists, 18 primary care clinicians, 16 medical geneticists, and 12 genetic counselors. Few clinicians felt their electronic record met their current genetic/genomic medicine needs. Barriers to integration were mostly related to problems with family history data collection, documentation, and organization. Lack of demand for genetics content and privacy concerns were also mentioned as challenges. Data elements and functionality requirements that clinicians see include: pedigree drawing; clinical decision support for familial risk assessment and genetic testing indications; a patient portal for patient-entered data; and standards for data elements, terminology, structure, interoperability, and clinical decision support rules. Although most said that there is little impact of genetics/genomics on electronic records today, many stated genetics/genomics would be a driver of content in the next 5-10 years. Electronic health records have the potential to enable clinical integration of genetic/genomic medicine and improve delivery of personalized health care; however, structured and standardized data elements and functionality requirements are needed.

How Many Words Does a Picture Really Tell? Cross-sectional Descriptive Study of Pictogram Evaluation by Youth

PubMed Central

Korenevsky, Artyom; Vaillancourt, Régis; Pouliot, Annie; Revol, Marine; Steed, Evan; Besançon, Luc; Wahrendorf, Marit-Saskia; Patel, Jaimisha R

2013-01-01

Background Communicating health-related instructions with pictograms is useful, but such graphics can be interpreted in different ways. It is crucial to understand which pictogram components are best for accurate communication. Objectives: To catalogue pictograms used to label drugs in clinical practice; to identify the common graphic elements for defined categories of pictograms, by performing a semiotic analysis (studying how signs are perceived and how they should be designed); to identify the key graphic elements common to pictograms preferred by users; and to develop suggestions for future pictogram design on the basis of users’ input. Methods: Literature and Internet searches were performed to identify pictograms and pictogram categories. A call for pictograms was also circulated through the International Pharmaceutical Federation (FIP). Youth at a Canadian pediatric hospital were asked to rate pictograms (including storyboards and prescription labels generated by FIP pictogram software) in terms of how best they represented their intended meanings. Pictograms for which at least 80% of participants “somewhat agreed”, “agreed”, or “strongly agreed” that the graphic conveyed the intended meaning were designated as “preferred” and were selected for analysis. Elements appearing in at least 50% of these preferred pictograms were highlighted as key graphic elements for design of future pictograms. Results: In total, 21 categories were identified for pictograms used in clinical practice, and a total of 204 pictograms were analyzed. Eighty-six participants took part in the survey. For each pictogram category, certain elements were identified as “preferred” and as “key graphic elements”, whereas other elements met neither designation. For all 21 pictogram categories, at least 80% of survey respondents agreed that the FIP storyboard conveyed the intended meaning. Conclusions: Certain key, preferred graphic elements are required for pharmaceutical pictograms to convey their intended meaning. The overlap between preferred and key pictogram elements indicates that both must be considered in development of future pictograms. Redesign of existing pictograms with consideration of the best semiotic elements is in progress. PMID:23950605

Semantic Segmentation of Building Elements Using Point Cloud Hashing

NASA Astrophysics Data System (ADS)

Chizhova, M.; Gurianov, A.; Hess, M.; Luhmann, T.; Brunn, A.; Stilla, U.

2018-05-01

For the interpretation of point clouds, the semantic definition of extracted segments from point clouds or images is a common problem. Usually, the semantic of geometrical pre-segmented point cloud elements are determined using probabilistic networks and scene databases. The proposed semantic segmentation method is based on the psychological human interpretation of geometric objects, especially on fundamental rules of primary comprehension. Starting from these rules the buildings could be quite well and simply classified by a human operator (e.g. architect) into different building types and structural elements (dome, nave, transept etc.), including particular building parts which are visually detected. The key part of the procedure is a novel method based on hashing where point cloud projections are transformed into binary pixel representations. A segmentation approach released on the example of classical Orthodox churches is suitable for other buildings and objects characterized through a particular typology in its construction (e.g. industrial objects in standardized enviroments with strict component design allowing clear semantic modelling).

Hybrid Manipulation of Streamwise Vorticity in a Diffuser Boundary Layer

NASA Astrophysics Data System (ADS)

Gissen, Abraham; Vukasinovic, Bojan; Culp, John; Glezer, Ari

2010-11-01

The formation of streamwise vorticity concentrations by exploiting the interaction of surface-mounted passive (micro-vanes) and active (synthetic jets) flow control elements with the cross flow is investigated experimentally in a small-scale serpentine duct at high subsonic speeds (up to M = 0.6). Streamwise vortices can be a key element in the mitigation of the adverse effects on pressure recovery and distortion caused by the naturally occurring secondary flows in embedded propulsion systems with complex inlet geometries. Counter rotating and single-sense vortices are formed using conventional passive micro-vanes and active high-power synthetic jet actuators. Interaction of the flow control elements is examined through a hybrid actuation scheme whereby synthetic jet actuation augments the primary vanes' vortices resulting in dynamic enhancement of their strength. It is shown that such sub-boundary layer individual vortices can merge and evolve into duct-scale vortical structures that counteract the inherent secondary flow and mitigates global flow distortion.

76 FR 6496 - Special Flight Rules Area in the Vicinity of Grand Canyon National Park, Draft Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-04

... being considered include: Alternative A Current Condition: Key elements are corridors open year round, annual allocation cap of 93,971, and no quiet technology incentive. Current tours for helicopters and... to quiet technology aircraft. Alternative F Modified Current Condition: Key elements are similar to...

The Secret to Finland's Success: Educating Teachers. Research Brief

ERIC Educational Resources Information Center

Sahlberg, Pasi

2010-01-01

In the last decade, Finland has emerged as the leading OECD country in educational achievement. In examining the sources of Finland's dramatic rise to the top, research shows one key element that has impacted Finland's success above all others: excellent teachers. This policy brief details the key elements of Finland's successful system, examining…

Modeling the mesozoic-cenozoic structural evolution of east texas

USGS Publications Warehouse

Pearson, Ofori N.; Rowan, Elisabeth L.; Miller, John J.

2012-01-01

The U.S. Geological Survey (USGS) recently assessed the undiscovered technically recoverable oil and gas resources within Jurassic and Cretaceous strata of the onshore coastal plain and State waters of the U.S. Gulf Coast. Regional 2D seismic lines for key parts of the Gulf Coast basin were interpreted in order to examine the evolution of structural traps and the burial history of petroleum source rocks. Interpretation and structural modeling of seismic lines from eastern Texas provide insights into the structural evolution of this part of the Gulf of Mexico basin. Since completing the assessment, the USGS has acquired additional regional seismic lines in east Texas; interpretation of these new lines, which extend from the Texas-Oklahoma state line to the Gulf Coast shoreline, show how some of the region's prominent structural elements (e.g., the Talco and Mount Enterprise fault zones, the East Texas salt basin, and the Houston diapir province) vary along strike. The interpretations also indicate that unexplored structures may lie beneath the current drilling floor. Structural restorations based upon interpretation of these lines illustrate the evolution of key structures and show the genetic relation between structural growth and movement of the Jurassic Louann Salt. 1D thermal models that integrate kinetics and burial histories were also created for the region's two primary petroleum source rocks, the Oxfordian Smackover Formation and the Cenomanian-Turonian Eagle Ford Shale. Integrating results from the thermal models with the structural restorations provides insights into the distribution and timing of petroleum expulsion from the Smackover Formation and Eagle Ford Shale in eastern Texas.

Novel dimeric interface and electrostatic recognition in bacterial Cu,Zn superoxide dismutase

PubMed Central

Bourne, Yves; Redford, Susan M.; Steinman, Howard M.; Lepock, James R.; Tainer, John A.; Getzoff, Elizabeth D.

1996-01-01

Eukaryotic Cu,Zn superoxide dismutases (CuZnSODs) are antioxidant enzymes remarkable for their unusually stable β-barrel fold and dimer assembly, diffusion-limited catalysis, and electrostatic guidance of their free radical substrate. Point mutations of CuZnSOD cause the fatal human neurodegenerative disease amyotrophic lateral sclerosis. We determined and analyzed the first crystallographic structure (to our knowledge) for CuZnSOD from a prokaryote, Photobacterium leiognathi, a luminescent symbiont of Leiognathid fish. This structure, exemplifying prokaryotic CuZnSODs, shares the active-site ligand geometry and the topology of the Greek key β-barrel common to the eukaryotic CuZnSODs. However, the β-barrel elements recruited to form the dimer interface, the strategy used to forge the channel for electrostatic recognition of superoxide radical, and the connectivity of the intrasubunit disulfide bond in P. leiognathi CuZnSOD are discrete and strikingly dissimilar from those highly conserved in eukaryotic CuZnSODs. This new CuZnSOD structure broadens our understanding of structural features necessary and sufficient for CuZnSOD activity, highlights a hitherto unrecognized adaptability of the Greek key β-barrel building block in evolution, and reveals that prokaryotic and eukaryotic enzymes diverged from one primordial CuZnSOD and then converged to distinct dimeric enzymes with electrostatic substrate guidance. PMID:8917495

A novel abundant family of retroposed elements (DAS-SINEs) in the nine-banded armadillo (Dasypus novemcinctus).

PubMed

Churakov, Gennady; Smit, Arian F A; Brosius, Jürgen; Schmitz, Jürgen

2005-04-01

About half of the mammalian genome is composed of retroposons. Long interspersed elements (LINEs) and short interspersed elements (SINEs) are the most abundant repetitive elements and account for about 21% and 13% of the human genome, respectively. SINEs have been detected in all major mammalian lineages, except for the South American order Xenarthra, also termed Edentata (armadillos, anteaters, and sloths). Investigating this order, we discovered a novel high-copy-number family of tRNA derived SINEs in the nine-banded armadillo Dasypus novemcinctus, a species that successfully crossed the Central American land bridge to North America in the Pliocene. A specific computer algorithm was developed, and we detected and extracted 687 specific SINEs from databases. Termed DAS-SINEs, we further divided them into six distinct subfamilies. We extracted tRNA(Ala)-derived monomers, two types of dimers, and three subfamilies of chimeric fusion products of a tRNA(Ala) domain and an approximately 180-nt sequence of thus far unidentified origin. Comparisons of secondary structures of the DAS-SINEs' tRNA domains suggest selective pressure to maintain a tRNA-like D-arm structure in the respective founder RNAs, as shown by compensatory mutations. By analysis of subfamily-specific genetic variability, comparison of the proportion of direct repeats, and analysis of self-integrations as well as key events of dimerization and deletions or insertions, we were able to delineate the evolutionary history of the DAS-SINE subfamilies.

Rocketdyne PSAM: In-house enhancement/application

NASA Technical Reports Server (NTRS)

Newell, J. F.; Rajagopal, K. R.; Ohara, K.

1991-01-01

The development was initiated of the Probabilistic Design Analysis (PDA) Process for rocket engines. This will enable engineers a quantitative assessment of calculated reliability during the design process. The PDA will help choose better designs, make them more robust, and help decide on critical tests to help demonstrate key reliability issues to aid in improving the confidence of the engine capabilities. Rockedyne's involvement with the Composite Loads Spectra (CLS) and Probabilistic Structural Analysis Methodology (PSAM) contracts started this effort and are key elements in the on-going developments. Internal development efforts and hardware applications complement and extend the CLS and PSAM efforts. The completion of the CLS option work and the follow-on PSAM developments will also be integral parts of this methodology. A brief summary of these efforts is presented.

The role of emotion in musical improvisation: an analysis of structural features.

PubMed

McPherson, Malinda J; Lopez-Gonzalez, Monica; Rankin, Summer K; Limb, Charles J

2014-01-01

One of the primary functions of music is to convey emotion, yet how music accomplishes this task remains unclear. For example, simple correlations between mode (major vs. minor) and emotion (happy vs. sad) do not adequately explain the enormous range, subtlety or complexity of musically induced emotions. In this study, we examined the structural features of unconstrained musical improvisations generated by jazz pianists in response to emotional cues. We hypothesized that musicians would not utilize any universal rules to convey emotions, but would instead combine heterogeneous musical elements together in order to depict positive and negative emotions. Our findings demonstrate a lack of simple correspondence between emotions and musical features of spontaneous musical improvisation. While improvisations in response to positive emotional cues were more likely to be in major keys, have faster tempos, faster key press velocities and more staccato notes when compared to negative improvisations, there was a wide distribution for each emotion with components that directly violated these primary associations. The finding that musicians often combine disparate features together in order to convey emotion during improvisation suggests that structural diversity may be an essential feature of the ability of music to express a wide range of emotion.

The Role of Emotion in Musical Improvisation: An Analysis of Structural Features

PubMed Central

McPherson, Malinda J.; Lopez-Gonzalez, Monica; Rankin, Summer K.; Limb, Charles J.

2014-01-01

One of the primary functions of music is to convey emotion, yet how music accomplishes this task remains unclear. For example, simple correlations between mode (major vs. minor) and emotion (happy vs. sad) do not adequately explain the enormous range, subtlety or complexity of musically induced emotions. In this study, we examined the structural features of unconstrained musical improvisations generated by jazz pianists in response to emotional cues. We hypothesized that musicians would not utilize any universal rules to convey emotions, but would instead combine heterogeneous musical elements together in order to depict positive and negative emotions. Our findings demonstrate a lack of simple correspondence between emotions and musical features of spontaneous musical improvisation. While improvisations in response to positive emotional cues were more likely to be in major keys, have faster tempos, faster key press velocities and more staccato notes when compared to negative improvisations, there was a wide distribution for each emotion with components that directly violated these primary associations. The finding that musicians often combine disparate features together in order to convey emotion during improvisation suggests that structural diversity may be an essential feature of the ability of music to express a wide range of emotion. PMID:25144200

A Combined Remote Sensing-Numerical Modelling Approach to the Stability Analysis of Delabole Slate Quarry, Cornwall, UK

NASA Astrophysics Data System (ADS)

Havaej, Mohsen; Coggan, John; Stead, Doug; Elmo, Davide

2016-04-01

Rock slope geometry and discontinuity properties are among the most important factors in realistic rock slope analysis yet they are often oversimplified in numerical simulations. This is primarily due to the difficulties in obtaining accurate structural and geometrical data as well as the stochastic representation of discontinuities. Recent improvements in both digital data acquisition and incorporation of discrete fracture network data into numerical modelling software have provided better tools to capture rock mass characteristics, slope geometries and digital terrain models allowing more effective modelling of rock slopes. Advantages of using improved data acquisition technology include safer and faster data collection, greater areal coverage, and accurate data geo-referencing far exceed limitations due to orientation bias and occlusion. A key benefit of a detailed point cloud dataset is the ability to measure and evaluate discontinuity characteristics such as orientation, spacing/intensity and persistence. This data can be used to develop a discrete fracture network which can be imported into the numerical simulations to study the influence of the stochastic nature of the discontinuities on the failure mechanism. We demonstrate the application of digital terrestrial photogrammetry in discontinuity characterization and distinct element simulations within a slate quarry. An accurately geo-referenced photogrammetry model is used to derive the slope geometry and to characterize geological structures. We first show how a discontinuity dataset, obtained from a photogrammetry model can be used to characterize discontinuities and to develop discrete fracture networks. A deterministic three-dimensional distinct element model is then used to investigate the effect of some key input parameters (friction angle, spacing and persistence) on the stability of the quarry slope model. Finally, adopting a stochastic approach, discrete fracture networks are used as input for 3D distinct element simulations to better understand the stochastic nature of the geological structure and its effect on the quarry slope failure mechanism. The numerical modelling results highlight the influence of discontinuity characteristics and kinematics on the slope failure mechanism and the variability in the size and shape of the failed blocks.

Situational awareness within objective structured clinical examination stations in undergraduate medical training - a literature search.

PubMed

Fischer, Markus A; Kennedy, Kieran M; Durning, Steven; Schijven, Marlies P; Ker, Jean; O'Connor, Paul; Doherty, Eva; Kropmans, Thomas J B

2017-12-21

Medical students may not be able to identify the essential elements of situational awareness (SA) necessary for clinical reasoning. Recent studies suggest that students have little insight into cognitive processing and SA in clinical scenarios. Objective Structured Clinical Examinations (OSCEs) could be used to assess certain elements of situational awareness. The purpose of this paper is to review the literature with a view to identifying whether levels of SA based on Endsley's model can be assessed utilising OSCEs during undergraduate medical training. A systematic search was performed pertaining to SA and OSCEs, to identify studies published between January 1975 (first paper describing an OSCE) and February 2017, in peer reviewed international journals published in English. PUBMED, EMBASE, PsycINFO Ovid and SCOPUS were searched for papers that described the assessment of SA using OSCEs among undergraduate medical students. Key search terms included "objective structured clinical examination", "objective structured clinical assessment" or "OSCE" and "non-technical skills", "sense-making", "clinical reasoning", "perception", "comprehension", "projection", "situation awareness", "situational awareness" and "situation assessment". Boolean operators (AND, OR) were used as conjunctions to narrow the search strategy, resulting in the limitation of papers relevant to the research interest. Areas of interest were elements of SA that can be assessed by these examinations. The initial search of the literature retrieved 1127 publications. Upon removal of duplicates and papers relating to nursing, paramedical disciplines, pharmacy and veterinary education by title, abstract or full text, 11 articles were eligible for inclusion as related to the assessment of elements of SA in undergraduate medical students. Review of the literature suggests that whole-task OSCEs enable the evaluation of SA associated with clinical reasoning skills. If they address the levels of SA, these OSCEs can provide supportive feedback and strengthen educational measures associated with higher diagnostic accuracy and reasoning abilities. Based on the findings, the early exposure of medical students to SA is recommended, utilising OSCEs to evaluate and facilitate SA in dynamic environments.

Practical private database queries based on a quantum-key-distribution protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakobi, Markus; Humboldt-Universitaet zu Berlin, D-10117 Berlin; Simon, Christoph

2011-02-15

Private queries allow a user, Alice, to learn an element of a database held by a provider, Bob, without revealing which element she is interested in, while limiting her information about the other elements. We propose to implement private queries based on a quantum-key-distribution protocol, with changes only in the classical postprocessing of the key. This approach makes our scheme both easy to implement and loss tolerant. While unconditionally secure private queries are known to be impossible, we argue that an interesting degree of security can be achieved by relying on fundamental physical principles instead of unverifiable security assumptions inmore » order to protect both the user and the database. We think that the scope exists for such practical private queries to become another remarkable application of quantum information in the footsteps of quantum key distribution.« less

Physiologically relevant organs on chips

PubMed Central

Yum, Kyungsuk; Hong, Soon Gweon; Lee, Luke P.

2015-01-01

Recent advances in integrating microengineering and tissue engineering have generated promising microengineered physiological models for experimental medicine and pharmaceutical research. Here we review the recent development of microengineered physiological systems, or organs on chips, that reconstitute the physiologically critical features of specific human tissues and organs and their interactions. This technology uses microengineering approaches to construct organ-specific microenvironments, reconstituting tissue structures, tissue–tissue interactions and interfaces, and dynamic mechanical and biochemical stimuli found in specific organs, to direct cells to assemble into functional tissues. We first discuss microengineering approaches to reproduce the key elements of physiologically important, dynamic mechanical microenvironments, biochemical microenvironments, and microarchitectures of specific tissues and organs in microfluidic cell culture systems. This is followed by examples of microengineered individual organ models that incorporate the key elements of physiological microenvironments into single microfluidic cell culture systems to reproduce organ-level functions. Finally, microengineered multiple organ systems that simulate multiple organ interactions to better represent human physiology, including human responses to drugs, is covered in this review. This emerging organs-on-chips technology has the potential to become an alternative to 2D and 3D cell culture and animal models for experimental medicine, human disease modeling, drug development, and toxicology. PMID:24357624

Treating first episode psychosis--the service users' perspective: a focus group evaluation.

PubMed

O'Toole, M S; Ohlsen, R I; Taylor, T M; Purvis, R; Walters, J; Pilowsky, L S

2004-06-01

UK national guidance has prioritized developing specialist services for first episode psychosis. Such services are in the early stages of development and a definitive treatment model has yet to be established. The aim of this study was to explore service users' experiences of a first episode intervention designed along evidence-based 'best practice' guidelines and to establish specific elements seen as effective to help inform future service planning and provision. Twelve users of a specialist first episode service participated in focus groups. These were then analyzed using Interpretative Phenomenological Analysis, a specialized form of content analysis. Key elements identified by the service users included the 'human' approach as a key to the recovery process, being involved in treatment decisions, flexibility of appointments, high nurse to patient ratio, reduction in psychotic symptoms, increased confidence and independence and the provision of daily structure. To our knowledge, this is the first systematic qualitative evaluation of users' experience of a specialist first episode treatment intervention. Our findings indicate that adherence to best practice guidelines was appreciated. Regular focus groups provide a continuous audit cycle incorporating service improvements in line with government recommendations, centrally informed by the service users' and caregivers' perspective.

Exploration Medical Capability System Engineering Introduction and Vision

NASA Technical Reports Server (NTRS)

Mindock, J.; Reilly, J.

2017-01-01

Human exploration missions to beyond low Earth orbit destinations such as Mars will require more autonomous capability compared to current low Earth orbit operations. For the medical system, lack of consumable resupply, evacuation opportunities, and real-time ground support are key drivers toward greater autonomy. Recognition of the limited mission and vehicle resources available to carry out exploration missions motivates the Exploration Medical Capability (ExMC) Element's approach to enabling the necessary autonomy. The Element's work must integrate with the overall exploration mission and vehicle design efforts to successfully provide exploration medical capabilities. ExMC is applying systems engineering principles and practices to accomplish its integrative goals. This talk will briefly introduce the discipline of systems engineering and key points in its application to exploration medical capability development. It will elucidate technical medical system needs to be met by the systems engineering work, and the structured and integrative science and engineering approach to satisfying those needs, including the development of shared mental and qualitative models within and external to the human health and performance community. These efforts are underway to ensure relevancy to exploration system maturation and to establish medical system development that is collaborative with vehicle and mission design and engineering efforts.

A quality function deployment framework for the service quality of health information websites.

PubMed

Chang, Hyejung; Kim, Dohoon

2010-03-01

This research was conducted to identify both the users' service requirements on health information websites (HIWs) and the key functional elements for running HIWs. With the quality function deployment framework, the derived service attributes (SAs) are mapped into the suppliers' functional characteristics (FCs) to derive the most critical FCs for the users' satisfaction. Using the survey data from 228 respondents, the SAs, FCs and their relationships were analyzed using various multivariate statistical methods such as principal component factor analysis, discriminant analysis, correlation analysis, etc. Simple and compound FC priorities were derived by matrix calculation. Nine factors of SAs and five key features of FCs were identified, and these served as the basis for the house of quality model. Based on the compound FC priorities, the functional elements pertaining to security and privacy, and usage support should receive top priority in the course of enhancing HIWs. The quality function deployment framework can improve the FCs of the HIWs in an effective, structured manner, and it can also be utilized for critical success factors together with their strategic implications for enhancing the service quality of HIWs. Therefore, website managers could efficiently improve website operations by considering this study's results.

Exploration of priority actions for strengthening the role of nurses in achieving universal health coverage

PubMed Central

Maaitah, Rowaida Al; AbuAlRub, Raeda Fawzi

2017-01-01

ABSTRACT Objective: to explore priority actions for strengthening the role of Advanced Practice Nurses (APNs) towards the achievement of Universal Health Converge (UHC) as perceived by health key informants in Jordan. Methods: an exploratory qualitative design, using a semi-structured survey, was utilized. A purposive sample of seventeen key informants from various nursing and health care sectors was recruited for the purpose of the study. Content analysis utilizing the five-stage framework approach was used for data analysis. Results: the findings revealed that policy and regulation, nursing education, research, and workforce were identified as the main elements that influence the role of APNs in contributing to the achievement of UHC. Priority actions were identified by the participants for the main four elements. Conclusion: study findings confirm the need to strengthen the role of APNs to achieve UHC through a major transformation in nursing education, practice, research, leadership, and regulatory system. Nurses should unite to come up with solid nursing competencies related to APNs, PHC, UHC, leadership and policy making to strengthen their position as main actors in influencing the health care system and evidence creation. PMID:28146176

Influence of ambient pressure on surface structures generated by ultrashort laser pulse irradiation

NASA Astrophysics Data System (ADS)

JJ Nivas, J.; Allahyari, E.; Gesuele, F.; Maddalena, P.; Fittipaldi, R.; Vecchione, A.; Bruzzese, R.; Amoruso, S.

2018-02-01

We report an experimental investigation on the surface structures induced by linearly polarized ≈ 900 fs laser pulses, at λ = 1055 nm, on silicon at different values of the ambient pressure, from 10-4 mbar to one atmosphere. Our experimental findings address interesting influences of the surrounding pressure on: (1) the spatial period of ripples; (2) the formation of micro-grooves; (3) the shape of the structured area. Moreover, the effects of various states of polarization in vacuum as well as of circularly polarized pulses in air vs vacuum are also addressed. We identify as one possible key element of such experimental observations: the fact that as the pressure raises the ablated nanoparticles produced during the femtosecond ablation process of the target get deposited more and more on the sample surface covering the irradiated spot area and influencing the structuring process.

Optimization of hierarchical structure and nanoscale-enabled plasmonic refraction for window electrodes in photovoltaics

PubMed Central

Han, Bing; Peng, Qiang; Li, Ruopeng; Rong, Qikun; Ding, Yang; Akinoglu, Eser Metin; Wu, Xueyuan; Wang, Xin; Lu, Xubing; Wang, Qianming; Zhou, Guofu; Liu, Jun-Ming; Ren, Zhifeng; Giersig, Michael; Herczynski, Andrzej; Kempa, Krzysztof; Gao, Jinwei

2016-01-01

An ideal network window electrode for photovoltaic applications should provide an optimal surface coverage, a uniform current density into and/or from a substrate, and a minimum of the overall resistance for a given shading ratio. Here we show that metallic networks with quasi-fractal structure provides a near-perfect practical realization of such an ideal electrode. We find that a leaf venation network, which possesses key characteristics of the optimal structure, indeed outperforms other networks. We further show that elements of hierarchal topology, rather than details of the branching geometry, are of primary importance in optimizing the networks, and demonstrate this experimentally on five model artificial hierarchical networks of varied levels of complexity. In addition to these structural effects, networks containing nanowires are shown to acquire transparency exceeding the geometric constraint due to the plasmonic refraction. PMID:27667099

Self-Chaperoning of the Type III Secretion System needle tip proteins IpaD and BipD

PubMed Central

Johnson, Steven; Roversi, Pietro; Espina, Marianela; Olive, Andrew; Deane, Janet E.; Birket, Susan; Field, Terry; Picking, William D.; Blocker, Ariel; Galyov, Edouard E.; Picking, Wendy L.; Lea, Susan M.

2007-01-01

Bacteria expressing type III secretion systems (T3SS) have been responsible for the deaths of millions worldwide, acting as key virulence elements in diseases ranging from plague to typhoid fever. The T3SS is composed of a basal body, which traverses both bacterial membranes, and an external needle through which effector proteins are secreted. We report multiple crystal structures of two proteins that sit at the tip of the needle and are essential for virulence; IpaD from Shigella flexneri and BipD from Burkholderia pseudomallei. The structures reveal that the N-terminal domains of the molecules are intra-molecular chaperones that prevent premature oligomerization, as well as sharing structural homology with proteins involved in eukaryotic actin rearrangement. Crystal packing has allowed us to construct a model for the tip complex that is supported by mutations designed using the structure. PMID:17077085

Side-wall spacer passivated sub-μm Josephson junction fabrication process

NASA Astrophysics Data System (ADS)

Grönberg, Leif; Kiviranta, Mikko; Vesterinen, Visa; Lehtinen, Janne; Simbierowicz, Slawomir; Luomahaara, Juho; Prunnila, Mika; Hassel, Juha

2017-12-01

We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a sidewall-passivating spacer structure (SWAPS) which is shaped for smooth crossline contacting and low parasitic capacitance. The SWAPS structure enables formation of junctions with dimensions at or below the lithography-limited linewidth. An additional benefit is avoiding the excessive use of amorphous dielectric materials which is favorable in sub-Kelvin microwave applications often plagued by nonlinear and lossy dielectrics. We apply the structure to niobium trilayer junctions, and provide characterization results yielding evidence on wafer-scale scalability, and critical current density tuning in the range of 0.1-3.0 kA cm-2. We discuss the applicability of the junction process in the context of different applications, such as SQUID magnetometers and Josephson parametric amplifiers.

Modelling of double air-bridged structured inductor implemented by a GaAs integrated passive device manufacturing process

NASA Astrophysics Data System (ADS)

Li, Yang; Yao, Zhao; Zhang, Chun-Wei; Fu, Xiao-Qian; Li, Zhi-Ming; Li, Nian-Qiang; Wang, Cong

2017-05-01

In order to provide excellent performance and show the development of a complicated structure in a module and system, this paper presents a double air-bridge-structured symmetrical differential inductor based on integrated passive device technology. Corresponding to the proposed complicated structure, a new manufacturing process fabricated on a high-resistivity GaAs substrate is described in detail. Frequency-independent physical models are presented with lump elements and the results of skin effect-based measurements. Finally, some key features of the inductor are compared; good agreement between the measurements and modeled circuit fully verifies the validity of the proposed modeling approach. Meanwhile, we also present a comparison of different coil turns for inductor performance. The proposed work can provide a good solution for the design, fabrication, modeling, and practical application of radio-frequency modules and systems.

Self-chaperoning of the type III secretion system needle tip proteins IpaD and BipD.

PubMed

Johnson, Steven; Roversi, Pietro; Espina, Marianela; Olive, Andrew; Deane, Janet E; Birket, Susan; Field, Terry; Picking, William D; Blocker, Ariel J; Galyov, Edouard E; Picking, Wendy L; Lea, Susan M

2007-02-09

Bacteria expressing type III secretion systems (T3SS) have been responsible for the deaths of millions worldwide, acting as key virulence elements in diseases ranging from plague to typhoid fever. The T3SS is composed of a basal body, which traverses both bacterial membranes, and an external needle through which effector proteins are secreted. We report multiple crystal structures of two proteins that sit at the tip of the needle and are essential for virulence: IpaD from Shigella flexneri and BipD from Burkholderia pseudomallei. The structures reveal that the N-terminal domains of the molecules are intramolecular chaperones that prevent premature oligomerization, as well as sharing structural homology with proteins involved in eukaryotic actin rearrangement. Crystal packing has allowed us to construct a model for the tip complex that is supported by mutations designed using the structure.

[Does clinical risk management require a structured conflict management?].

PubMed

Neumann, Stefan

2015-01-01

A key element of clinical risk management is the analysis of errors causing near misses or patient damage. After analyzing the causes and circumstances, measures for process improvement have to be taken. Process management, human resource development and other established methods are used. If an interpersonal conflict is a contributory factor to the error, there is usually no structured conflict management available which includes selection criteria for various methods of conflict processing. The European University Viadrina in Frankfurt (Oder) has created a process model for introducing a structured conflict management system which is suitable for hospitals and could fill the gap in the methodological spectrum of clinical risk management. There is initial evidence that a structured conflict management reduces staff fluctuation and hidden conflict costs. This article should be understood as an impulse for discussion on to what extent the range of methods of clinical risk management should be complemented by conflict management.

Halo Nuclei

NASA Astrophysics Data System (ADS)

Al-Khalili, Jim

2017-10-01

While neutron halos were discovered 30 years ago, this is the first book written on the subject of this exotic form of nuclei that typically contain many more neutrons than stable isotopes of those elements. It provides an introductory description of the halo and outlines the discovery and evidence for its existence. It also discusses different theoretical models of the halo's structure as well as models and techniques in reaction theory that have allowed us to study the halo. This is written at the graduate student (starting at PhD) level. The author of the book, Jim Al-Khalili, is a theoretician who published some of the key papers on the structure of the halo in the mid and late 90s and was the first to determine its true size. This monograph is based on review articles he has written on the mathematical models used to determine the halo structure and the reactions used to model that structure.

Aluminum automotive space frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-08-01

Design of aluminum structures is to a new topic. Aircraft makers have successfully solved difficult structural problems with a high degree of understanding and reliability. Other transportation modes such as trucks, trailers, and railcars have faced structural problems with some emphasis on high- and low-cycle fatigue of welded aluminum structures. However, the automotive market places stringent engineering demands on materials and superimposes demanding cost constraints. A project was instituted at Reynolds Metals Co. to investigate the opportunities for the cost-effective application of aluminum to automotive spaceframes. Several areas were recognized as key to the success of this application. They were:more » equivalent or superior structural stiffness of the assembly to existing steel unibody and/or steel spaceframe vehicles; effective joining of spaceframe members; equivalent or superior crashworthiness of the assembly; weight savings; flexibility; and low-cost approach aimed at effective manufacturing. To gain experience with the key aspects in a practical environment, the experience of current builders of steel tube frame chassis was explored. These chassis are typically used in low-volume vehicles requiring torsional stiffness, excellent crashworthiness, and exterior body-style flexibility. A model was developed using finite element methods that accurately predicts mass and stiffness of frames. An effective aluminum space frame was generated which was 7.5% stiffer and more than 20% lighter than the steel frame, with stresses kept below the fatigue limit for aluminum welds.« less

Li-atoms-induced structure changes of Guinier–Preston–Bagaryatsky zones in AlCuLiMg alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, S.Y.; Le, Z.; Chen, Z.K.

2016-11-15

Guinier–Preston–Bagaryatsky (GPB) zones are the well-known strengthening precipitates of AlCuMg alloys formed upon thermal ageing. Here we report that when formed in AlCuLiMg alloys the GPB zones can change significantly in morphology and structure. It is shown that though they do still consist of Al, Cu and Mg elements fundamentally, the GPB zones in AlCuLiMg alloys have a rather different structure due to a featured Li-segregation at their interfaces with the matrix and possible Li-replacement of partial Mg atoms in the structure. As such the Li-containing GPB zones often develop from one-dimensional to quasi-two-dimensional precipitates. - Highlights: • We observemore » Guinier–Preston–Bagaryatsky zone variants in AlCuLiMg alloys. • We obtain atomic-resolution images of the precipitates and model their structures. • Li-atoms play a key role in modifying the structure of these precipitate variants.« less

The selection criteria elements of X-ray optics system

NASA Astrophysics Data System (ADS)

Plotnikova, I. V.; Chicherina, N. V.; Bays, S. S.; Bildanov, R. G.; Stary, O.

2018-01-01

At the design of new modifications of x-ray tomography there are difficulties in the right choice of elements of X-ray optical system. Now this problem is solved by practical consideration, selection of values of the corresponding parameters - tension on an x-ray tube taking into account the thickness and type of the studied material. For reduction of time and labor input of design it is necessary to create the criteria of the choice, to determine key parameters and characteristics of elements. In the article two main elements of X-ray optical system - an x-ray tube and the detector of x-ray radiation - are considered. Criteria of the choice of elements, their key characteristics, the main dependences of parameters, quality indicators and also recommendations according to the choice of elements of x-ray systems are received.

Integrated transient thermal-structural finite element analysis

NASA Technical Reports Server (NTRS)

Thornton, E. A.; Dechaumphai, P.; Wieting, A. R.; Tamma, K. K.

1981-01-01

An integrated thermal structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. Integrated thermal structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction elasticity solutions and conventional finite element thermal finite element structural analyses.

Key Elements in Successful Training A Comparative Study of Two Workplaces. Project Report, 2000-2001.

ERIC Educational Resources Information Center

Adult Literacy and Numeracy Australian Research Consortium, Alice Springs. Northern Territory Centre.

This publication presents case studies of two sites--one with and one without a history of involvement in Workplace English Language and Literacy (WELL)-funded training programs. Case study 1, "Partnership, Flexibility, and Experience: Key Elements in Successful Training" (Jenny McGuirk), investigates a food processing company in New South Wales…

Organic memristive device as key element for neuromorphic networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erokhin, Victor

Organic memristive device has three important properties allowing to consider it as a key element of neuromorphic systems. First, its electrical properties are somehow similar to those of synapses. Second, it can be easily transferred into an oscillator. Third, organic nature of the devices allow to assemble them into stochastic 3D networks capable to learning and adaptations.

How Strategic Planning Keeps You Sane when Delivering Distance Programs

ERIC Educational Resources Information Center

MacNeil, Dixie; Luzius, Kim; Dunkin, Sonya

2010-01-01

This paper details the advantages of creating a strategic plan in the development and delivery of distance programs at the authors' own institution. The steps involved in the planning process and the three key elements of a successful strategic plan are addressed. The key elements include a program plan explaining the roles/responsibilities of…

Environmental mineralogy - Understanding element behavior in ecosystems

NASA Astrophysics Data System (ADS)

Brown, Gordon E., Jr.; Calas, Georges

2011-02-01

Environmental Mineralogy has developed over the past decade in response to the recognition that minerals are linked in many important ways with the global ecosystem. Minerals are the main repositories of the chemical elements in Earth's crust and thus are the main sources of elements needed for the development of civilization, contaminant and pollutant elements that impact global and local ecosystems, and elements that are essential plant nutrients. These elements are released from minerals through natural processes, such as chemical weathering, and anthropogenic activities, such as mining and energy production, agriculture and industrial activities, and careless waste disposal. Minerals also play key roles in the biogeochemical cycling of the elements, sequestering elements and releasing them as the primary minerals in crustal rocks undergo various structural and compositional transformations in response to physical, chemical, and biological processes that produce secondary minerals and soils. These processes have resulted in the release of toxic elements such as arsenic in groundwater aquifers, which is having a major impact on the health of millions of people in South and Southeast Asia. The interfaces between mineral surfaces and aqueous solutions are the locations of most chemical reactions that control the composition of the natural environment, including the composition of natural waters. The nuclear fuel cycle, from uranium mining to the disposition of high-level nuclear waste, is also intimately related to minerals. A fundamental understanding of these processes requires molecular-scale information about minerals, their bulk structures and properties such as solubility, their surfaces, and their interactions with aqueous solutions, atmospheric and soil gases, natural organic matter, and biological organisms. Gaining this understanding is further complicated by the presence of natural, incidental, and manufactured nanoparticles in the environment, which are becoming increasingly important due to the rapidly developing field of nanotechnology. As a result of this complexity, Environmental Mineralogy requires the use of the most modern molecular-scale analytical and theoretical methods and overlaps substantially with closely related fields such as Environmental Sciences, low-temperature Geochemistry, and Geomicrobiology. This paper provides brief overviews of the above topics and discusses the complexity of minerals, natural vs. anthropogenic inputs of elements and pollutants into the biosphere, the role of minerals in the biogeochemical cycling of elements, natural nanoparticles, and the Environmental Mineralogy of three major potential pollutant elements (Hg, As and U).

Thermal Protection System of the Space Shuttle

NASA Technical Reports Server (NTRS)

Cleland, John; Iannetti, Francesco

1989-01-01

The Thermal Protection System (TPS), introduced by NASA, continues to incorporate many of the advances in materials over the past two decades. A comprehensive, single-volume summary of the TPS, including system design rationales, key design features, and broad descriptions of the subsystems of TPS (E.g., reusable surface insulation, leading edge structural, and penetration subsystems) is provided. Details of all elements of TPS development and application are covered (materials properties, manufacturing, modeling, testing, installation, and inspection). Disclosures and inventions are listed and potential commercial application of TPS-related technology is discussed.

Flexible Twist for Pitch Control in a High Altitude Long Endurance Aircraft with Nonlinear Response

DTIC Science & Technology

2008-12-01

Information dominance is the key motivator for employing high-altitude long-endurance (HALE) aircraft to provide continuous coverage in the theaters of operation A joined-wing configuration of such a craft gives the advantage of a platform for higher resolution sensors. Design challenges emerge with structural flexibility that arise from a long-endurance aircraft design. The goal was to demonstrate that scaling the nonlinear response of a full-scale finite element model of a high-altitude long-endurance (HALE) aircraft was possible if the model was aeroelastically and

Pilots' Information Needs and Strategies for Operating in Icing Conditions

NASA Technical Reports Server (NTRS)

Vigeant-Langlois, Laurence N.; Hansman, R. John

2003-01-01

Pilot current use of icing information, pilot encounters and strategies for dealing with in-flight aircraft structural icing situations, and desired attributes of new icing information systems were investigated through a survey of pilots of several operational categories. The survey identified important information elements and fiequently used information paths for obtaining icing-related information. Free- response questions solicited descriptions of significant , icing encounters, and probed key icing-related decision and information criteria. Results indicated the information needs for the horizontal and vertical location of icing conditions and the identification of icing-free zones.

Public health preparedness: evolution or revolution?

PubMed

Lurie, Nicole; Wasserman, Jeffrey; Nelson, Christopher D

2006-01-01

The recent emphasis on preparedness has created heightened expectations and has raised questions about the extent to which U.S. public health systems have evolved in recent years. This paper describes how public health preparedness is transforming public health agencies. Key signs of change include new partnerships, changes in the workforce, new technologies, and evolving organizational structures. Each of these elements has had some positive impact on public health; however, integration of preparedness with other public health functions remains challenging. The preparedness mission has also raised challenges in the areas of leadership, governance, quality, and accountability.

A Probabilistic Approach to Model Update

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Reaves, Mercedes C.; Voracek, David F.

2001-01-01

Finite element models are often developed for load validation, structural certification, response predictions, and to study alternate design concepts. In rare occasions, models developed with a nominal set of parameters agree with experimental data without the need to update parameter values. Today, model updating is generally heuristic and often performed by a skilled analyst with in-depth understanding of the model assumptions. Parameter uncertainties play a key role in understanding the model update problem and therefore probabilistic analysis tools, developed for reliability and risk analysis, may be used to incorporate uncertainty in the analysis. In this work, probability analysis (PA) tools are used to aid the parameter update task using experimental data and some basic knowledge of potential error sources. Discussed here is the first application of PA tools to update parameters of a finite element model for a composite wing structure. Static deflection data at six locations are used to update five parameters. It is shown that while prediction of individual response values may not be matched identically, the system response is significantly improved with moderate changes in parameter values.

The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: Boeing Helicopters airframe finite element modeling

NASA Technical Reports Server (NTRS)

Gabel, R.; Lang, P.; Reed, D.

1993-01-01

Mathematical models based on the finite element method of structural analysis, as embodied in the NASTRAN computer code, are routinely used by the helicopter industry to calculate airframe static internal loads used for sizing structural members. Historically, less reliance has been placed on the vibration predictions based on these models. Beginning in the early 1980's NASA's Langley Research Center initiated an industry wide program with the objective of engendering the needed trust in vibration predictions using these models and establishing a body of modeling guides which would enable confident future prediction of airframe vibration as part of the regular design process. Emphasis in this paper is placed on the successful modeling of the Army/Boeing CH-47D which showed reasonable correlation with test data. A principal finding indicates that improved dynamic analysis requires greater attention to detail and perhaps a finer mesh, especially the mass distribution, than the usual stress model. Post program modeling efforts show improved correlation placing key modal frequencies in the b/rev range with 4 percent of the test frequencies.

Key ingredients of anti-stigma programs for health care providers: a data synthesis of evaluative studies.

PubMed

Knaak, Stephanie; Modgill, Geeta; Patten, Scott B

2014-10-01

As part of its ongoing effort to combat stigma against mental illness among health care providers, the Mental Health Commission of Canada partnered with organizations conducting anti-stigma interventions. Our objective was to evaluate program effectiveness and to better understand what makes some programs more effective than others. Our paper reports the elements of these programs found to be most strongly associated with favourable outcomes. Our study employed a multi-phased, mixed-methods design. First, a grounded theory qualitative study was undertaken to identify key program elements. Next, each program (n = 22) was coded according to the presence or absence of the identified key program ingredients. Then, random-effects, meta-regression modelling was used to examine the association between program outcomes and the key ingredients. The qualitative analysis led to a 6-ingredient model of key program elements. Results of the quantitative analysis showed that programs that included all 6 of these ingredients performed significantly better than those that did not. Individual analyses of each of the 6 ingredients showed that including multiple forms of social contact and emphasizing recovery were characteristics of the most effective programs. The results provide a validation of a 6-ingredient model of key program elements for anti-stigma programming for health care providers. Emphasizing recovery and including multiple types of social contact are of particular importance for maximizing the effectiveness of anti-stigma programs for health care providers.

Fault diagnosis of rolling element bearing using a new optimal scale morphology analysis method.

PubMed

Yan, Xiaoan; Jia, Minping; Zhang, Wan; Zhu, Lin

2018-02-01

Periodic transient impulses are key indicators of rolling element bearing defects. Efficient acquisition of impact impulses concerned with the defects is of much concern to the precise detection of bearing defects. However, transient features of rolling element bearing are generally immersed in stochastic noise and harmonic interference. Therefore, in this paper, a new optimal scale morphology analysis method, named adaptive multiscale combination morphological filter-hat transform (AMCMFH), is proposed for rolling element bearing fault diagnosis, which can both reduce stochastic noise and reserve signal details. In this method, firstly, an adaptive selection strategy based on the feature energy factor (FEF) is introduced to determine the optimal structuring element (SE) scale of multiscale combination morphological filter-hat transform (MCMFH). Subsequently, MCMFH containing the optimal SE scale is applied to obtain the impulse components from the bearing vibration signal. Finally, fault types of bearing are confirmed by extracting the defective frequency from envelope spectrum of the impulse components. The validity of the proposed method is verified through the simulated analysis and bearing vibration data derived from the laboratory bench. Results indicate that the proposed method has a good capability to recognize localized faults appeared on rolling element bearing from vibration signal. The study supplies a novel technique for the detection of faulty bearing. Copyright © 2018. Published by Elsevier Ltd.

Automatic Method for Building Indoor Boundary Models from Dense Point Clouds Collected by Laser Scanners

PubMed Central

Valero, Enrique; Adán, Antonio; Cerrada, Carlos

2012-01-01

In this paper we present a method that automatically yields Boundary Representation Models (B-rep) for indoors after processing dense point clouds collected by laser scanners from key locations through an existing facility. Our objective is particularly focused on providing single models which contain the shape, location and relationship of primitive structural elements of inhabited scenarios such as walls, ceilings and floors. We propose a discretization of the space in order to accurately segment the 3D data and generate complete B-rep models of indoors in which faces, edges and vertices are coherently connected. The approach has been tested in real scenarios with data coming from laser scanners yielding promising results. We have deeply evaluated the results by analyzing how reliably these elements can be detected and how accurately they are modeled. PMID:23443369

Discrete element modeling of shock-induced particle jetting

NASA Astrophysics Data System (ADS)

Xue, Kun; Cui, Haoran

2018-05-01

The dispersal of particle shell or ring by divergent impulsive loads takes the form of coherent particle jets with the dimensions several orders larger than that of constituent grain. Particle-scale simulations based on the discrete element method have been carried out to reveal the evolution of jets in semi-two-dimensional rings before they burst out of the external surface. We identify two key events which substantially change the resulted jetting pattern, specifically, the annihilation of incipient jets and the tip-slipping of jets, which become active in different phases of jet evolution. Parametric investigations have been done to assess the correlations between the jetting pattern and a variety of structural parameters. Overpressure, the internal and outer diameters of ring as well as the packing density are found to have effects on the jet evolution with different relative importance.

Does Don Fisher's high-pressure manifold model account for phloem transport and resource partitioning?

PubMed Central

Patrick, John W.

2013-01-01

The pressure flow model of phloem transport envisaged by Münch (1930) has gained wide acceptance. Recently, however, the model has been questioned on structural and physiological grounds. For instance, sub-structures of sieve elements may reduce their hydraulic conductances to levels that impede flow rates of phloem sap and observed magnitudes of pressure gradients to drive flow along sieve tubes could be inadequate in tall trees. A variant of the Münch pressure flow model, the high-pressure manifold model of phloem transport introduced by Donald Fisher may serve to reconcile at least some of these questions. To this end, key predicted features of the high-pressure manifold model of phloem transport are evaluated against current knowledge of the physiology of phloem transport. These features include: (1) An absence of significant gradients in axial hydrostatic pressure in sieve elements from collection to release phloem accompanied by transport properties of sieve elements that underpin this outcome; (2) Symplasmic pathways of phloem unloading into sink organs impose a major constraint over bulk flow rates of resources translocated through the source-path-sink system; (3) Hydraulic conductances of plasmodesmata, linking sieve elements with surrounding phloem parenchyma cells, are sufficient to support and also regulate bulk flow rates exiting from sieve elements of release phloem. The review identifies strong circumstantial evidence that resource transport through the source-path-sink system is consistent with the high-pressure manifold model of phloem transport. The analysis then moves to exploring mechanisms that may link demand for resources, by cells of meristematic and expansion/storage sinks, with plasmodesmal conductances of release phloem. The review concludes with a brief discussion of how these mechanisms may offer novel opportunities to enhance crop biomass yields. PMID:23802003

Identification and characterization of new members of the SXT/R391 family of integrative and conjugative elements (ICEs) in Proteus mirabilis.

PubMed

Bie, Luyao; Wu, Hao; Wang, Xin-Hua; Wang, Mingyu; Xu, Hai

2017-08-01

Integrative and conjugative elements (ICEs) are self-transmissible chromosomal mobile elements that play significant roles in the dissemination of antimicrobial resistance genes. Identification of the structures and functions of ICEs, particularly those in pathogens, improves understanding of the dissemination of antimicrobial resistance. This study identified new members of the sulfamethoxazole-trimethoprim (SXT)/R391 family of ICEs that could confer multi-drug resistance in the opportunistic pathogen Proteus mirabilis, characterized their genetic structures, and explored their evolutionary connection with other members of this family of ICEs. Three new members of the SXT/R391 family of ICEs were detected in six of 77 P. mirabilis strains isolated in China: ICEPmiChn2 (one strain), ICEPmiChn3 (one strain) and ICEPmiChn4 (three strains). All three new ICEs harbour antimicrobial resistance genes from diverse origins, suggesting their capability in acquiring foreign genes and serving as important carriers for antimicrobial resistance genes. Structural analysis showed that ICEPmiChn3 is a particularly interesting and unique ICE that has lost core genes involved in conjugation, and could not transfer to other cells via conjugation. This finding confirmed the key roles of these missing genes in conjugation. Further phylogenetic analysis suggested that ICEs in geographically close strains are also connected evolutionarily, and ICEPmiChn3 lost its conjugation cassette from a former mobile ICE. The identification and characterization of the three new members of the SXT/R391 family of ICEs in this work leads to suggestions of core ICE genes essential for conjugation, and extends understanding on the structures of ICEs, evolutionary relationships between ICEs, and the antimicrobial resistance mechanisms of P. mirabilis. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Quantitative atomic-scale structure characterization of ordered mesoporous carbon materials by solid state NMR

DOE PAGES

Wang, Zhuoran; Opembe, Naftali; Kobayashi, Takeshi; ...

2018-02-03

In this study, solid-state (SS)NMR techniques were applied to characterize the atomic-scale structures of ordered mesoporous carbon (OMC) materials prepared using Pluronic F127 as template with resorcinol and formaldehyde as polymerizing precursors. A rigorous quantitative analysis was developed using a combination of 13C SSNMR spectra acquired with direct polarization and cross polarization on natural abundant and selectively 13C-enriched series of samples pyrolyzed at various temperatures. These experiments identified and counted the key functional groups present in the OMCs at various stages of preparation and thermal treatment. Lastly, the chemical evolution of molecular networks, the average sizes of aromatic clusters andmore » the extended molecular structures of OMCs were then inferred by coupling this information with the elemental analysis results.« less

Quantitative atomic-scale structure characterization of ordered mesoporous carbon materials by solid state NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhuoran; Opembe, Naftali; Kobayashi, Takeshi

In this study, solid-state (SS)NMR techniques were applied to characterize the atomic-scale structures of ordered mesoporous carbon (OMC) materials prepared using Pluronic F127 as template with resorcinol and formaldehyde as polymerizing precursors. A rigorous quantitative analysis was developed using a combination of 13C SSNMR spectra acquired with direct polarization and cross polarization on natural abundant and selectively 13C-enriched series of samples pyrolyzed at various temperatures. These experiments identified and counted the key functional groups present in the OMCs at various stages of preparation and thermal treatment. Lastly, the chemical evolution of molecular networks, the average sizes of aromatic clusters andmore » the extended molecular structures of OMCs were then inferred by coupling this information with the elemental analysis results.« less

Interplay between I308 and Y310 residues in the third repeat of microtubule-binding domain is essential for tau filament formation.

PubMed

Naruto, Keiko; Minoura, Katsuhiko; Okuda, Ryouhei; Taniguchi, Taizo; In, Yasuko; Ishida, Toshimasa; Tomoo, Koji

2010-10-08

Investigation of the mechanism of tau polymerization is indispensable for finding inhibitory conditions or identifying compounds preventing the formation of paired helical filament or oligomers. Tau contains a microtubule-binding domain consisting of three or four repeats in its C-terminal half. It has been considered that the key event in tau polymerization is the formation of a β-sheet structure arising from a short hexapeptide (306)VQIVYK(311) in the third repeat of tau. In this paper, we report for the first time that the C-H⋯π interaction between Ile308 and Tyr310 is the elemental structural scaffold essential for forming a dry "steric zipper" structure in tau amyloid fibrils. Copyright © 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Evaporation on/in Capillary Structures of High Heat Flux Two-Phase Devices

NASA Technical Reports Server (NTRS)

Faghri, Amir; Khrustalev, Dmitry

1996-01-01

Two-phase devices (heat pipes, capillary pumped loops, loop heat pipes, and evaporators) have become recognized as key elements in thermal control systems of space platforms. Capillary and porous structures are necessary and widely used in these devices, especially in high heat flux and zero-g applications, to provide fluid transport and enhanced heat transfer during vaporization and condensation. However, some unexpected critical phenomena, such as dryout in long heat pipe evaporators and high thermal resistance of loop heat pipe evaporators with high heat fluxes, are possible and have been encountered in the use of two-phase devices in the low gravity environment. Therefore, a detailed fundamental investigation is proposed to better understand the fluid behavior in capillary-porous structures during vaporization at high heat fluxes. The present paper addresses some theoretical aspects of this investigation.

Manufacturing and NDE of Large Composite Structures for Space Transportation at MSFC

NASA Technical Reports Server (NTRS)

McGill, Preston; Russell, Sam

2000-01-01

This paper presents the Marshall Space Flight Center's (MSFC's) vision to manufacture, increase safety and reduce the cost of launch vehicles. Nondestructive evaluations of large composite structures are tested for space transportation at MSFC. The topics include: 1) 6 1/2 Generations of Airplanes in a Century; 2) Shuttle Safety Upgrades; 3) Generations of Reusable Launch Vehicles; 4) RLV Technology Demonstration Path; 5) Second Generation; 6) Key NASA Requirements; 7) X-33 Elements; 8) Future-X Pathfinder Projects and Experiments; 9) Focus Area Technical Goals; 10) X-34 Expanded View; 11) X-38 Spacecraft with De-Orbit Propulsion Stage (DPS); 12) Deorbit Module (DM) Critical Design Review (CDR) Design; 13) Forward Structural Adapter (FSA) CDR Design; 14) X-38 DPS CDR Design; 15) RLV Focused Propulsion Technologies; and 16) Challenges in Technology. This paper is presented in viewgraph form.

Mechanical Characterization of Partially Crystallized Sphere Packings

NASA Astrophysics Data System (ADS)

Hanifpour, M.; Francois, N.; Vaez Allaei, S. M.; Senden, T.; Saadatfar, M.

2014-10-01

We study grain-scale mechanical and geometrical features of partially crystallized packings of frictional spheres, produced experimentally by a vibrational protocol. By combining x-ray computed tomography, 3D image analysis, and discrete element method simulations, we have access to the 3D structure of internal forces. We investigate how the network of mechanical contacts and intergranular forces change when the packing structure evolves from amorphous to near perfect crystalline arrangements. We compare the behavior of the geometrical neighbors (quasicontracts) of a grain to the evolution of the mechanical contacts. The mechanical coordination number Zm is a key parameter characterizing the crystallization onset. The high fluctuation level of Zm and of the force distribution in highly crystallized packings reveals that a geometrically ordered structure still possesses a highly random mechanical backbone similar to that of amorphous packings.

Structural characterization and viscoelastic constitutive modeling of skin.

PubMed

Sherman, Vincent R; Tang, Yizhe; Zhao, Shiteng; Yang, Wen; Meyers, Marc A

2017-04-15

A fascinating material, skin has a tensile response which exhibits an extended toe region of minimal stress up to nominal strains that, in some species, exceed 1, followed by significant stiffening until a roughly linear region. The large toe region has been attributed to its unique structure, consisting of a network of curved collagen fibers. Investigation of the structure of rabbit skin reveals that it consists of layers of wavy fibers, each one with a characteristic orientation. Additionally, the existence of two preferred layer orientations is suggested based on the results of small angle X-ray scattering. These observations are used to construct a viscoelastic model consisting of collagen in two orientations, which leads to an in-plane anisotropic response. The structure-based model presented incorporates the elastic straightening and stretching of fibrils, their rotation towards the tensile axis, and the viscous effects which occur in the matrix of the skin due to interfibrillar and interlamellar sliding. The model is shown to effectively capture key features which dictate the mechanical response of skin. Examination by transmission and scanning electron microscopy of rabbit dermis enabled the identification of the key elements in its structure. The organization of collagen fibrils into flat fibers was identified and incorporated into a constitutive model that reproduces the mechanical response of skin. This enhanced quantitative predictive capability can be used in the design of synthetic skin and skin-like structures. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Student Voice in a Chinese Context: Investigating the Key Elements of Leadership That Enhance Student Voice

ERIC Educational Resources Information Center

Cheng, Annie Yan Ni

2012-01-01

This study examines the issues surrounding "student voice" in a specific Chinese context, and assesses the key elements of leadership that could enhance student voice in that context. It reports the results of a research conducted in a community-based educational centre in Hong Kong that provides after-school educational and social…

Drawing with Light and Clay: Teaching and Learning in the Art Studio as Pathways to Engagement

ERIC Educational Resources Information Center

Albertson, Constant; Davidson, Miriam

2007-01-01

In this essay, Albertson and Davidson explore the attributes of photography and ceramic arts education to identify eight key elements integral to engagement in these art studios for under-served and disenchanted learners. They suggest that these key elements can provide numerous clues as to how teachers and school communities might reimagine both…

California Charter Oversight: Key Elements and Actual Costs. CRB 12-001

ERIC Educational Resources Information Center

Blanton, Rebecca E.

2012-01-01

This study was mandated by SB537 (Simitian, Chapter 650, Stats. of 2007, codified at Ed. Code Section 47613), which requires the California Research Bureau (CRB) to prepare and submit to the Legislature a report on the key elements and actual costs of charter school oversight. Charter schools are public schools that are operated by entities other…

Note: Silicon Carbide Telescope Dimensional Stability for Space-based Gravitational Wave Detectors

NASA Technical Reports Server (NTRS)

Sanjuah, J.; Korytov, D.; Mueller, G.; Spannagel, R.; Braxmaier, C.; Preston, A.; Livas, J.

2012-01-01

Space-based gravitational wave detectors are conceived to detect gravitational waves in the low frequency range by measuring the distance between proof masses in spacecraft separated by millions of kilometers. One of the key elements is the telescope which has to have a dimensional stability better than 1 pm Hz(exp -1/2) at 3 mHz. In addition, the telescope structure must be light, strong, and stiff. For this reason a potential telescope structure consisting of a silicon carbide quadpod has been designed, constructed, and tested. We present dimensional stability results meeting the requirements at room temperature. Results at -60 C are also shown although the requirements are not met due to temperature fluctuations in the setup.

Computational procedures for evaluating the sensitivity derivatives of vibration frequencies and Eigenmodes of framed structures

NASA Technical Reports Server (NTRS)

Fetterman, Timothy L.; Noor, Ahmed K.

1987-01-01

Computational procedures are presented for evaluating the sensitivity derivatives of the vibration frequencies and eigenmodes of framed structures. Both a displacement and a mixed formulation are used. The two key elements of the computational procedure are: (a) Use of dynamic reduction techniques to substantially reduce the number of degrees of freedom; and (b) Application of iterative techniques to improve the accuracy of the derivatives of the eigenmodes. The two reduction techniques considered are the static condensation and a generalized dynamic reduction technique. Error norms are introduced to assess the accuracy of the eigenvalue and eigenvector derivatives obtained by the reduction techniques. The effectiveness of the methods presented is demonstrated by three numerical examples.

Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

2009-02-01

The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as αTi = 872.4 and αO = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences ΔTi = (BE O 1s - BE Ti 2p3/2) = 71.6 eV and ΔLa = (BE La 3d5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

Electronic structure of layered titanate Nd 2Ti 2O 7

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

2008-10-01

The electronic structure of the binary titanate Nd 2Ti 2O 7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd 2Ti 2O 7 are determined as αTi = 873.5 and αO = 1042.2 eV. Chemical bonding effects have been discussed with the binding energies differences ΔTi = (BE O 1s - BE Ti 2p 3/2) = 71.5 eV and ΔNd = (BE Nd 3d 5/2 - BE O 1s) = 452.5 eV as key parameters in comparison with those in other titanium- and neodymium-bearing oxides.

Folding and unfolding single RNA molecules under tension

PubMed Central

Woodside, Michael T; García-García, Cuauhtémoc; Block, Steven M

2010-01-01

Single-molecule force spectroscopy constitutes a powerful method for probing RNA folding: it allows the kinetic, energetic, and structural properties of intermediate and transition states to be determined quantitatively, yielding new insights into folding pathways and energy landscapes. Recent advances in experimental and theoretical methods, including fluctuation theorems, kinetic theories, novel force clamps, and ultrastable instruments, have opened new avenues for study. These tools have been used to probe folding in simple model systems, for example, RNA and DNA hairpins. Knowledge gained from such systems is helping to build our understanding of more complex RNA structures composed of multiple elements, as well as how nucleic acids interact with proteins involved in key cellular activities, such as transcription and translation. PMID:18786653

Structure-efficiency relationships of cyclodextrin scavengers in the hydrolytic degradation of organophosphorus compounds.

PubMed

Letort, Sophie; Bosco, Michaël; Cornelio, Benedetta; Brégier, Frédérique; Daulon, Sébastien; Gouhier, Géraldine; Estour, François

2017-01-01

New derivatives of cyclodextrins were prepared in order to determine the relative importance of the structural key elements involved in the degradation of organophosphorus nerve agents. To avoid a competitive inclusion between the organophosphorus substrate and the iodosobenzoate group, responsible for its degradation, the latter group had to be covalently bound to the cyclodextrin scaffold. Although the presence of the α nucleophile iodosobenzoate was a determinant in the hydrolysis process, an imidazole group was added to get a synergistic effect towards the degradation of the agents. The degradation efficiency was found to be dependent on the relative position of the heterocycle towards the reactive group as well as on the nature of the organophosphorus derivative.

Note: silicon carbide telescope dimensional stability for space-based gravitational wave detectors.

PubMed

Sanjuán, J; Korytov, D; Mueller, G; Spannagel, R; Braxmaier, C; Preston, A; Livas, J

2012-11-01

Space-based gravitational wave detectors are conceived to detect gravitational waves in the low frequency range by measuring the distance between proof masses in spacecraft separated by millions of kilometers. One of the key elements is the telescope which has to have a dimensional stability better than 1 pm Hz(-1/2) at 3 mHz. In addition, the telescope structure must be light, strong, and stiff. For this reason a potential telescope structure consisting of a silicon carbide quadpod has been designed, constructed, and tested. We present dimensional stability results meeting the requirements at room temperature. Results at -60 °C are also shown although the requirements are not met due to temperature fluctuations in the setup.

The Geometry of Resonant Signatures in Debris Disks with Planets

NASA Astrophysics Data System (ADS)

Kuchner, M. J.; Holman, M. J.

2002-09-01

Using simple geometrical arguments, we paint an overview of the variety of resonant structures a single planet with moderate eccentricity (e < 0.6) can create in a dynamically cold, optically thin dust disk. This overview may serve as a key for interpreting images of perturbed debris disks and inferring the dynamical properties of the planets responsible for the perturbations. We compare the resonant structures found in the solar system with observations of planetary systems around Vega and other stars and we offer a new model for the asymmetries in the Epsilon Eridani disk. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) through the Michelson Fellowship program funded by NASA as an element of the Planet Finder Program.

The long (LINEs) and the short (SINEs) of it: altered methylation as a precursor to toxicity.

PubMed

Carnell, Ammie N; Goodman, Jay I

2003-10-01

Although once thought of as "junk" DNA, the importance of interspersed elements in the genome has become increasingly appreciated in recent years. In a broad sense these are collectively referred to as transposable elements, which encompass both transposons and retrotransposons. The latter include long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs). Expression of these elements leads to genetic instability. Therefore, it is important that they remain transcriptionally silenced, and DNA methylation plays a key role in this regard. A framework for understanding the possible interplay between altered DNA methylation, an epigenetic change, and mutational events is presented. A case is made as to how retrotransposable elements, specifically LINEs and SINEs, are likely to emerge as key players in furthering our understanding of mechanisms underlying a variety of toxicities, including carcinogenesis but not limited to this endpoint.

Studying the effect of cracks on the ultrasonic wave propagation in a two dimensional gearbox finite element model

NASA Astrophysics Data System (ADS)

Ozevin, Didem; Fazel, Hossein; Cox, Justin; Hardman, William; Kessler, Seth S.; Timmons, Alan

2014-04-01

Gearbox components of aerospace structures are typically made of brittle materials with high fracture toughness, but susceptible to fatigue failure due to continuous cyclic loading. Structural Health Monitoring (SHM) methods are used to monitor the crack growth in gearbox components. Damage detection methodologies developed in laboratory-scale experiments may not represent the actual gearbox structural configuration, and are usually not applicable to real application as the vibration and wave properties depend on the material, structural layers and thicknesses. Also, the sensor types and locations are key factors for frequency content of ultrasonic waves, which are essential features for pattern recognition algorithm development in noisy environments. Therefore, a deterministic damage detection methodology that considers all the variables influencing the waveform signature should be considered in the preliminary computation before any experimental test matrix. In order to achieve this goal, we developed two dimensional finite element models of a gearbox cross section from front view and shaft section. The cross section model consists of steel revolving teeth, a thin layer of oil, and retention plate. An ultrasonic wave up to 1 MHz frequency is generated, and waveform histories along the gearbox are recorded. The received waveforms under pristine and cracked conditions are compared in order to analyze the crack influence on the wave propagation in gearbox, which can be utilized by both active and passive SHM methods.

Improved finite element methodology for integrated thermal structural analysis

NASA Technical Reports Server (NTRS)

Dechaumphai, P.; Thornton, E. A.

1982-01-01

An integrated thermal-structural finite element approach for efficient coupling of thermal and structural analysis is presented. New thermal finite elements which yield exact nodal and element temperatures for one dimensional linear steady state heat transfer problems are developed. A nodeless variable formulation is used to establish improved thermal finite elements for one dimensional nonlinear transient and two dimensional linear transient heat transfer problems. The thermal finite elements provide detailed temperature distributions without using additional element nodes and permit a common discretization with lower order congruent structural finite elements. The accuracy of the integrated approach is evaluated by comparisons with analytical solutions and conventional finite element thermal structural analyses for a number of academic and more realistic problems. Results indicate that the approach provides a significant improvement in the accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

A credit card verifier structure using diffraction and spectroscopy concepts

NASA Astrophysics Data System (ADS)

Sumriddetchkajorn, Sarun; Intaravanne, Yuttana

2008-04-01

We propose and experimentally demonstrate an angle-multiplexing based optical structure for verifying a credit card. Our key idea comes from the fact that the fine detail of the embossed hologram stamped on the credit card is hard to duplicate and therefore its key color features can be used for distinguishing between the real and counterfeit ones. As the embossed hologram is a diffractive optical element, we choose to shine one at a time a number of broadband lightsources, each at different incident angle, on the embossed hologram of the credit card in such a way that different color spectra per incident angle beam is diffracted and separated in space. In this way, the number of pixels of each color plane is investigated. Then we apply a feed forward back propagation neural network configuration to separate the counterfeit credit card from the real one. Our experimental demonstration using two off-the-shelf broadband white light emitting diodes, one digital camera, a 3-layer neural network, and a notebook computer can identify all 69 counterfeit credit cards from eight real credit cards.

Building the Nonuniversity, Tertiary Care Center Hepatobiliary and Pancreatic Surgery Practice: Structural and Financial Considerations.

PubMed

Baker, Erin H; Siddiqui, Imran; Vrochides, Dionisios; Iannitti, David A; Martinie, John B; Rorabaugh, Lauren; Jeyarajah, D Rohan; Swan, Ryan Z

2016-12-01

Early in their careers, many new surgeons lack the background and experience to understand essential components needed to build a surgical practice. Surgical resident education is often devoid of specific instruction on the business of medicine and practice management. In particular, hepatobiliary and pancreatic (HPB) surgeons require many key components to build a successful practice secondary to significant interdisciplinary coordination and a scope of complex surgery, which spans challenging benign and malignant disease processes. In the following, we describe the required clinical and financial components for developing a successful HPB surgery practice in the nonuniversity tertiary care center. We discuss significant financial considerations for understanding community need and hospital investment, contract establishment, billing, and coding. We summarize the structural elements and key personnel necessary for establishing an effectual HPB surgical team. This article provides useful, essential information for a new HPB surgeon looking to establish a surgical practice. It also provides insight for health-care administrators as to the value an HPB surgeon can bring to a hospital or health-care system.

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data

NASA Astrophysics Data System (ADS)

Wolery, Thomas J.; Jové Colón, Carlos F.

2017-09-01

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data. Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO2, water, and aqueous species such as Na+ and Cl-. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15 K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of "links" to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare "key" or "reference" datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.

The interplay of contextual elements in implementation: an ethnographic case study.

PubMed

McCullough, Megan B; Chou, Ann F; Solomon, Jeffrey L; Petrakis, Beth Ann; Kim, Bo; Park, Angela M; Benedict, Ashley J; Hamilton, Alison B; Rose, Adam J

2015-02-14

Contextual elements have significant impact on uptake of health care innovations. While existing conceptual frameworks in implementation science suggest contextual elements interact with each other, little research has described how this might look in practice. To bridge this gap, this study identifies the interconnected patterns among contextual elements that influence uptake of an anticoagulation clinic improvement initiative. We completed 51 semi-structured interviews and ethnographic observations across five case study sites involved in an evidence-based practice (EBP) quality improvement initiative. We analyzed data in NVivo 10 using an a priori approach based on the Promoting Action on Research Implementation in Health Services (PARIHS) model and an emergent thematic analysis. Key contextual elements, such as leadership, teamwork, and communication, interacted with each other in contributing to site-level uptake of the EBP, often yielding results that could not be predicted by looking at just one of these elements alone. Sites with context conducive to change in these areas predictably had high uptake, while sites with uniformly weak contextual elements had low uptake. Most sites presented a mixed picture, with contextual elements being strongly supportive of change in some areas and weak or moderate in others. In some cases, we found that sites with strong context in at least one area only needed to have adequate context in other areas to yield high uptake. At other sites, weak context in just one area had the potential to contribute to low uptake, despite countervailing strengths. Even a site with positive views of EBPs could not succeed when context was weak. Interrelationships among different contextual elements can act as barriers to uptake at some sites and as facilitators at others. Accounting for interconnections among elements enables PARIHS to more fully describe the determinants of successful implementation as they operate in real-world settings.

Teaching learning methods of an entrepreneurship curriculum.

PubMed

Esmi, Keramat; Marzoughi, Rahmatallah; Torkzadeh, Jafar

2015-10-01

One of the most significant elements of entrepreneurship curriculum design is teaching-learning methods, which plays a key role in studies and researches related to such a curriculum. It is the teaching method, and systematic, organized and logical ways of providing lessons that should be consistent with entrepreneurship goals and contents, and should also be developed according to the learners' needs. Therefore, the current study aimed to introduce appropriate, modern, and effective methods of teaching entrepreneurship and their validation. This is a mixed method research of a sequential exploratory kind conducted through two stages: a) developing teaching methods of entrepreneurship curriculum, and b) validating developed framework. Data were collected through "triangulation" (study of documents, investigating theoretical basics and the literature, and semi-structured interviews with key experts). Since the literature on this topic is very rich, and views of the key experts are vast, directed and summative content analysis was used. In the second stage, qualitative credibility of research findings was obtained using qualitative validation criteria (credibility, confirmability, and transferability), and applying various techniques. Moreover, in order to make sure that the qualitative part is reliable, reliability test was used. Moreover, quantitative validation of the developed framework was conducted utilizing exploratory and confirmatory factor analysis methods and Cronbach's alpha. The data were gathered through distributing a three-aspect questionnaire (direct presentation teaching methods, interactive, and practical-operational aspects) with 29 items among 90 curriculum scholars. Target population was selected by means of purposive sampling and representative sample. Results obtained from exploratory factor analysis showed that a three factor structure is an appropriate method for describing elements of teaching-learning methods of entrepreneurship curriculum. Moreover, the value for Kaiser Meyer Olkin measure of sampling adequacy equaled 0.72 and the value for Bartlett's test of variances homogeneity was significant at the 0.0001 level. Except for internship element, the rest had a factor load of higher than 0.3. Also, the results of confirmatory factor analysis showed the model appropriateness, and the criteria for qualitative accreditation were acceptable. Developed model can help instructors in selecting an appropriate method of entrepreneurship teaching, and it can also make sure that the teaching is on the right path. Moreover, the model is comprehensive and includes all the effective teaching methods in entrepreneurship education. It is also based on qualities, conditions, and requirements of Higher Education Institutions in Iranian cultural environment.

Progress in the structural understanding of voltage-gated calcium channel (CaV) function and modulation.

PubMed

Minor, Daniel L; Findeisen, Felix

2010-01-01

Voltage-gated calcium channels (CaVs) are large, transmembrane multiprotein complexes that couple membrane depolarization to cellular calcium entry. These channels are central to cardiac action potential propagation, neurotransmitter and hormone release, muscle contraction, and calcium-dependent gene transcription. Over the past six years, the advent of high-resolution structural studies of CaV components from different isoforms and CaV modulators has begun to reveal the architecture that underlies the exceptionally rich feedback modulation that controls CaV action. These descriptions of CaV molecular anatomy have provided new, structure-based insights into the mechanisms by which particular channel elements affect voltage-dependent inactivation (VDI), calcium‑dependent inactivation (CDI), and calcium‑dependent facilitation (CDF). The initial successes have been achieved through structural studies of soluble channel domains and modulator proteins and have proven most powerful when paired with biochemical and functional studies that validate ideas inspired by the structures. Here, we review the progress in this growing area and highlight some key open challenges for future efforts.

Cooperativity governs the size and structure of biological interfaces.

PubMed

Qin, Zhao; Buehler, Markus J

2012-11-15

Interfaces, defined as the surface of interactions between two parts of a system at a discontinuity, are very widely found in nature. While it is known that the specific structure of an interface plays an important role in defining its properties, it is less clear whether or not there exist universal scaling laws that govern the structural evolution of a very broad range of natural interfaces. Here we show that cooperativity of interacting elements, leading to great strength at low material use, is a key concept that governs the structural evolution of many natural interfaces. We demonstrate this concept for the cases of β-sheet proteins in spider silk, gecko feet, legs of caterpillars, and self-assembling of penguins into huddles, which range in scales from the submolecular to the macroscopic level. A general model is proposed that explains the size and structure of biological interfaces from a fundamental point of view. Copyright © 2012 Elsevier Ltd. All rights reserved.

Rigor-like structures from muscle myosins reveal key mechanical elements in the transduction pathways of this allosteric motor.

PubMed

Yang, Yuting; Gourinath, S; Kovács, Mihály; Nyitray, László; Reutzel, Robbie; Himmel, Daniel M; O'Neall-Hennessey, Elizabeth; Reshetnikova, Ludmilla; Szent-Györgyi, Andrew G; Brown, Jerry H; Cohen, Carolyn

2007-05-01

Unlike processive cellular motors such as myosin V, whose structure has recently been determined in a "rigor-like" conformation, myosin II from contracting muscle filaments necessarily spends most of its time detached from actin. By using squid and sea scallop sources, however, we have now obtained similar rigor-like atomic structures for muscle myosin heads (S1). The significance of the hallmark closed actin-binding cleft in these crystal structures is supported here by actin/S1-binding studies. These structures reveal how different duty ratios, and hence cellular functions, of the myosin isoforms may be accounted for, in part, on the basis of detailed differences in interdomain contacts. Moreover, the rigor-like position of switch II turns out to be unique for myosin V. The overall arrangements of subdomains in the motor are relatively conserved in each of the known contractile states, and we explore qualitatively the energetics of these states.

Ultrasonic wave-based structural health monitoring embedded instrument.

PubMed

Aranguren, G; Monje, P M; Cokonaj, Valerijan; Barrera, Eduardo; Ruiz, Mariano

2013-12-01

Piezoelectric sensors and actuators are the bridge between electronic and mechanical systems in structures. This type of sensor is a key element in the integrity monitoring of aeronautic structures, bridges, pressure vessels, wind turbine blades, and gas pipelines. In this paper, an all-in-one system for Structural Health Monitoring (SHM) based on ultrasonic waves is presented, called Phased Array Monitoring for Enhanced Life Assessment. This integrated instrument is able to generate excitation signals that are sent through piezoelectric actuators, acquire the received signals in the piezoelectric sensors, and carry out signal processing to check the health of structures. To accomplish this task, the instrument uses a piezoelectric phased-array transducer that performs the actuation and sensing of the signals. The flexibility and strength of the instrument allow the user to develop and implement a substantial part of the SHM technique using Lamb waves. The entire system is controlled using configuration software and has been validated through functional, electrical loading, mechanical loading, and thermal loading resistance tests.

Structure of the Mitochondrial Aminolevulinic Acid Synthase, a Key Heme Biosynthetic Enzyme.

PubMed

Brown, Breann L; Kardon, Julia R; Sauer, Robert T; Baker, Tania A

2018-04-03

5-Aminolevulinic acid synthase (ALAS) catalyzes the first step in heme biosynthesis. We present the crystal structure of a eukaryotic ALAS from Saccharomyces cerevisiae. In this homodimeric structure, one ALAS subunit contains covalently bound cofactor, pyridoxal 5'-phosphate (PLP), whereas the second is PLP free. Comparison between the subunits reveals PLP-coupled reordering of the active site and of additional regions to achieve the active conformation of the enzyme. The eukaryotic C-terminal extension, a region altered in multiple human disease alleles, wraps around the dimer and contacts active-site-proximal residues. Mutational analysis demonstrates that this C-terminal region that engages the active site is important for ALAS activity. Our discovery of structural elements that change conformation upon PLP binding and of direct contact between the C-terminal extension and the active site thus provides a structural basis for investigation of disruptions in the first step of heme biosynthesis and resulting human disorders. Copyright © 2018 Elsevier Ltd. All rights reserved.

Structural Responses and Finite Element Modeling of Hakka Tulou Rammed Earth Structures

NASA Astrophysics Data System (ADS)

Sranislawski, Daniel

Hakka Tulous are rammed earth structures that have survived the effects of aging and natural elements upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed earth, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous. Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also providing thermal comfort. Reports of self healing cracks in the rammed earth walls were also analyzed for their validity in this study. The study has found that although the story of the self healing crack cannot be validated, there is reason to believe that with the existence of lime, some type of autogenous healing could occur on a small scale. The study has also found, through the use of nondestructive testing, that both the internal wooden systems (flooring, roof, and column support) and the rammed earth walls, are still structurally sound. Also, rammed earth's high thermal mass along with the use of sufficient shading has allowed for a delay release of heat energy from the walls of the Tulous, thus providing thermal comfort that can be felt during both night and day temperatures. The Hakka Tulou structures have been found to resist destruction from natural disasters such as strong earthquakes even when more modern construction has not. Through finite element modeling, this study has shown that the high volume of rammed earth used in the construction of the Hakka Tulous helps dissipate lateral force energy into much lower stresses for the rammed earth wall. This absorption of lateral force energy allows the rammed earth structures to survive even the strongest of earthquakes experienced in the region. The Hakka Tulou, if rated by the LEED green building certification program, would earn the highest certification as this rammed earth construction has offered efficient living for hundreds of years. As historic as these rammed earth structures are, they present an environmentally friendly option to structures of the future.

Social and structural aspects of the overdose risk environment in St. Petersburg, Russia.

PubMed

Green, Traci C; Grau, Lauretta E; Blinnikova, Ksenia N; Torban, Mikhail; Krupitsky, Evgeny; Ilyuk, Ruslan; Kozlov, Andrei; Heimer, Robert

2009-05-01

While overdose is a common cause of mortality among opioid injectors worldwide, little information exists on opioid overdoses or how context may influence overdose risk in Russia. This study sought to uncover social and structural aspects contributing to fatal overdose risk in St. Petersburg and assess prevention intervention feasibility. Twenty-one key informant interviews were conducted with drug users, treatment providers, toxicologists, police, and ambulance staff. Thematic coding of interview content was conducted to elucidate elements of the overdose risk environment. Several factors within St. Petersburg's environment were identified as shaping illicit drug users' risk behaviours and contributing to conditions of suboptimal response to overdose in the community. Most drug users live and experience overdoses at home, where family and home environment may mediate or moderate risk behaviours. The overdose risk environment is also worsened by inefficient emergency response infrastructure, insufficient cardiopulmonary or naloxone training resources, and the preponderance of abstinence-based treatment approaches to the exclusion of other treatment modalities. However, attitudes of drug users and law enforcement officials generally support overdose prevention intervention feasibility. Modifiable aspects of the risk environment suggest community-based and structural interventions, including overdose response training for drug users and professionals that encompasses naloxone distribution to the users and equipping more ambulances with naloxone. Local social and structural elements influence risk environments for overdose. Interventions at the community and structural levels to prevent and respond to opioid overdoses are needed for and integral to reducing overdose mortality in St. Petersburg.

Anatomical features associated with water transport in imperforate tracheary elements of vessel-bearing angiosperms

PubMed Central

Sano, Yuzou; Morris, Hugh; Shimada, Hiroshi; Ronse De Craene, Louis P.; Jansen, Steven

2011-01-01

Background and Aims Imperforate tracheary elements (ITEs) in wood of vessel-bearing angiosperms may or may not transport water. Despite the significance of hydraulic transport for defining ITE types, the combination of cell structure with water transport visualization in planta has received little attention. This study provides a quantitative analysis of structural features associated with the conductive vs. non-conductive nature of ITEs. Methods Visualization of water transport was studied in 15 angiosperm species by dye injection and cryo-scanning electron microscopy. Structural features of ITEs were examined using light and electron microscopy. Key Results ITEs connected to each other by pit pairs with complete pit membranes contributed to water transport, while cells showing pit membranes with perforations up to 2 µm were hydraulically not functional. A close relationship was found between pit diameter and pit density, with both characters significantly higher in conductive than in non-conductive cells. In species with both conductive and non-conductive ITEs, a larger diameter was characteristic of the conductive cells. Water transport showed no apparent relationship with the length of ITEs and vessel grouping. Conclusions The structure and density of pits between ITEs represent the main anatomical characters determining water transport. The pit membrane structure of ITEs provides a reliable, but practically challenging, criterion to determine their conductive status. It is suggested that the term tracheids should strictly be used for conductive ITEs, while fibre-tracheids and libriform fibres are non-conductive. PMID:21385773

Evaluation of hypophosphatemia: lessons from patients with genetic disorders

PubMed Central

Bacchetta, Justine; Salusky, Isidro B

2014-01-01

Phosphate is a key element for several physiological pathways, such as skeletal development, bone mineralization, membrane composition, nucleotide structure, maintenance of plasma pH, and cellular signaling. The kidneys have a key role in phosphate homeostasis with three hormones playing important roles in renal phosphate handling (i.e., parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and 1-25 dihydroxy-vitamin D). Independently of the genetic diseases affecting the FGF23 pathway (such as hypophosphatemic rickets), hypophosphatemia is a frequent condition in daily practice, and untreated severe hypophosphatemia can induce hemolysis, rhabdomyolysis, respiratory failure, cardiac dysfunction and neurological impairment, thus requiring a rapid correction to avoid severe complications. The aims of this case report are to summarize the etiologies and the biological evaluation of hypophosphatemia in adults, and to provide an overview of our current understanding of phosphate metabolism. PMID:22075221

Motivational interviewing for HIV risk reduction among gay men in commercial and public sex settings.

PubMed

Harding, R; Dockrell, M J; Dockrell, J; Corrigan, N

2001-08-01

The present paper addresses the feasibility of combining motivational interviewing and cognitive interventions to HIV risk reduction in commercial venues and public sex environments (PSEs). The logic for these two approaches is considered and an intervention combining key elements of the two is presented. The intervention uses a questionnaire format to encourage individuals to compare their desired versus actual behaviour (i.e. chosen personal risk reduction strategy versus 'slip-ups'/unwanted risk taking), and to recognize their risk-related cognitions. High-risk individuals are identified, and health-focused conversations developed from the brief schedule. The structure and key design issues in the development of a feasible, acceptable and evidence-based tool are reviewed. The limitations of more complex, focused interventions in the context of commercial and PSE settings are discussed.

Element-topology-independent preconditioners for parallel finite element computations

NASA Technical Reports Server (NTRS)

Park, K. C.; Alexander, Scott

1992-01-01

A family of preconditioners for the solution of finite element equations are presented, which are element-topology independent and thus can be applicable to element order-free parallel computations. A key feature of the present preconditioners is the repeated use of element connectivity matrices and their left and right inverses. The properties and performance of the present preconditioners are demonstrated via beam and two-dimensional finite element matrices for implicit time integration computations.

Streamline integration as a method for two-dimensional elliptic grid generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiesenberger, M., E-mail: Matthias.Wiesenberger@uibk.ac.at; Held, M.; Einkemmer, L.

We propose a new numerical algorithm to construct a structured numerical elliptic grid of a doubly connected domain. Our method is applicable to domains with boundaries defined by two contour lines of a two-dimensional function. Furthermore, we can adapt any analytically given boundary aligned structured grid, which specifically includes polar and Cartesian grids. The resulting coordinate lines are orthogonal to the boundary. Grid points as well as the elements of the Jacobian matrix can be computed efficiently and up to machine precision. In the simplest case we construct conformal grids, yet with the help of weight functions and monitor metricsmore » we can control the distribution of cells across the domain. Our algorithm is parallelizable and easy to implement with elementary numerical methods. We assess the quality of grids by considering both the distribution of cell sizes and the accuracy of the solution to elliptic problems. Among the tested grids these key properties are best fulfilled by the grid constructed with the monitor metric approach. - Graphical abstract: - Highlights: • Construct structured, elliptic numerical grids with elementary numerical methods. • Align coordinate lines with or make them orthogonal to the domain boundary. • Compute grid points and metric elements up to machine precision. • Control cell distribution by adaption functions or monitor metrics.« less

On diamond, graphitic and amorphous carbons in primitive extraterrestrial solar system materials

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1990-01-01

Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H) and chaoite. Elemental carbon also occurs as amorphous carbon and poorly graphitized (or turbostratic) carbon but of all the forms of elemental carbon only graphite is stable under physical conditions that prevail in small Solar System bodies and in the interstellar medium. The recent discovery of cubic diamond in carbonaceous chondrites and hexagonal diamond in chondritic interplanetary dust particles (IDPs) have created a renewed interest in the crystalline elemental carbons that were not formed by shock processes on a parent body. Another technique, Raman spectroscopy, confirms a widespread occurrence of disordered graphite in the Allende carbonaceous chondrite and in chondritic IDPs. Elemental carbons have also been identified by their characteristic K-edge features in electron energy loss spectra (EELS). However, the spectroscopic data do not necessarily coincide with those obtained by selected area electron diffraction (SAED). In order to interpret these data in terms of rational crystalline structures, it may be useful to consider the principles underlying electron diffraction and spectroscopic analyses. Electron diffraction depends on electron scattering, on the type of atom and the distance between atoms in a crystal lattice. Spectroscopic data are a function of the type of atom and the energy of bonds between atoms. Also, SAED is a bulk sampling technique when compared to techniques such as Raman spectroscopy or EELS. Thus, it appears that combined analyses provide contradictory results and that amorphous, or short-range ordered, carbon identified by conventional TEM imaging and SAED may show evidence for sp(3) bonds in EELS spectra. It is suggested that complex, nanometer-scale, mineralogical interrelations are common to all elemental carbons irrespective of their origin. The subsequent thermal history, or energy balance, will determine the ultimate microstructure.

How causal analysis can reveal autonomy in models of biological systems

NASA Astrophysics Data System (ADS)

Marshall, William; Kim, Hyunju; Walker, Sara I.; Tononi, Giulio; Albantakis, Larissa

2017-11-01

Standard techniques for studying biological systems largely focus on their dynamical or, more recently, their informational properties, usually taking either a reductionist or holistic perspective. Yet, studying only individual system elements or the dynamics of the system as a whole disregards the organizational structure of the system-whether there are subsets of elements with joint causes or effects, and whether the system is strongly integrated or composed of several loosely interacting components. Integrated information theory offers a theoretical framework to (1) investigate the compositional cause-effect structure of a system and to (2) identify causal borders of highly integrated elements comprising local maxima of intrinsic cause-effect power. Here we apply this comprehensive causal analysis to a Boolean network model of the fission yeast (Schizosaccharomyces pombe) cell cycle. We demonstrate that this biological model features a non-trivial causal architecture, whose discovery may provide insights about the real cell cycle that could not be gained from holistic or reductionist approaches. We also show how some specific properties of this underlying causal architecture relate to the biological notion of autonomy. Ultimately, we suggest that analysing the causal organization of a system, including key features like intrinsic control and stable causal borders, should prove relevant for distinguishing life from non-life, and thus could also illuminate the origin of life problem. This article is part of the themed issue 'Reconceptualizing the origins of life'.

Diversity of Cobalamin Riboswitches in the Corrinoid-Producing Organohalide Respirer Desulfitobacterium hafniense

PubMed Central

Choudhary, Pallavi K.; Duret, Aurélie; Rohrbach-Brandt, Emmanuelle; Holliger, Christof; Sigel, Roland K. O.

2013-01-01

The strategic adaptation of prokaryotes in polluted niches involves the efficient regulation of their metabolism. The obligate anaerobe and metabolically versatile Desulfitobacterium hafniense reductively dechlorinates halogenated organic compounds (so-called organohalides). Some D. hafniense strains carry out organohalide respiration (OHR), a process which requires the use of corrinoid as a cofactor in reductive dehalogenases, the key enzymes in OHR. We report here the diversity of the cobalamin riboswitches that possibly regulate the corrinoid metabolism for D. hafniense. The analysis of available D. hafniense genomes indicates the presence of 18 cobalamin riboswitches located upstream of genes whose products are mainly involved in corrinoid biosynthesis and transport. To obtain insight into their function, the secondary structures of three of these RNA elements were predicted by Mfold, as well as analyzed by in-line probing. These RNA elements both display diversity in their structural elements and exhibit various affinities toward adenosylcobalamin that possibly relates to their role in the regulation of corrinoid metabolism. Furthermore, adenosylcobalamin-induced in vivo repression of RNA synthesis of the downstream located genes indicates that the corrinoid transporters and biosynthetic enzymes in D. hafniense strain TCE1 are regulated at the transcriptional level. Taken together, the riboswitch-mediated regulation of the complex corrinoid metabolism in D. hafniense could be of crucial significance in environments polluted with organohalides both to monitor their intracellular corrinoid level and to coexist with corrinoid-auxotroph OHR bacteria. PMID:24039263

Strategies to initiate and control the nucleation behavior of bimetallic nanoparticles.

PubMed

Krishnan, Gopi; de Graaf, Sytze; Ten Brink, Gert H; Persson, Per O Å; Kooi, Bart J; Palasantzas, George

2017-06-22

In this work we report strategies to nucleate bimetallic nanoparticles (NPs) made by gas phase synthesis of elements showing difficulty in homogeneous nucleation. It is shown that the nucleation assisted problem of bimetallic NP synthesis can be solved via the following pathways: (i) selecting an element which can itself nucleate and act as a nucleation center for the synthesis of bimetallic NPs; (ii) introducing H 2 or CH 4 as an impurity/trace gas to initiate nucleation during the synthesis of bimetallic NPs. The latter can solve the problem if none of the elements in a bimetallic NP can initiate nucleation. We illustrate the abovementioned strategies for the case of Mg based bimetallic NPs, which are interesting as hydrogen storage materials and exhibit both nucleation and oxidation issues even under ultra-high vacuum conditions. In particular, it is shown that adding H 2 in small proportions favors the formation of a solid solution/alloy structure even in the case of immiscible Mg and Ti, where normally phase separation occurs during synthesis. In addition, we illustrate the possibility of improving the nucleation rate, and controlling the structure and size distribution of bimetallic NPs using H 2 /CH 4 as a reactive/nucleating gas. This is shown to be associated with the dimer bond energies of the various formed species and the vapor pressures of the metals, which are key factors for NP nucleation.

Testing Spatial Correlation of Subduction Interplate Coupling and Forearc Morpho-Tectonics

NASA Technical Reports Server (NTRS)

Goldfinger, Chris; Meigs, Andrew; Meigs, Andrew; Kaye, Grant D.; VanLaningham, Sam

2005-01-01

Subduction zones that are capable of generating great (Mw greater than 8) earthquakes appear to have a common assemblage of forearc morphologic elements. Although details vary, each have (from the trench landward), an accretionary prism, outer arc high, outer forearc basin, an inner forean: basin, and volcanic arc. This pattern is common in spite of great variation in forearc architecture. Because interseismic strain is known to be associated with a locked seismogenic plate interface, we infer that this common forearc morphology is related, in an unknown way, to the process of interseismic Strain accumulation and release in great earthquakes. To date, however, no clear relationship between the subduction process and the common elements of upper plate form has emerged. Whereas certain elements of the system, i.e. the outer arc high, are reasonably well- understood in a structural context, there is little understanding of the structural or topographic evolution of the other key elements like the inner arc and inner forearc basin, particularly with respect to the coupled zone of earthquake generation. This project developed a model of the seismologic, topographic, and uplift/denudation linkages between forearc topography and the subduction system by: 1) comparing geophysical, geodetic, and topographic data from subduction margins that generate large earthquakes; 2) using existing GPS, seismicity, and other data to model the relationship between seismic cycles involving a locked interface and upper-plate topographic development; and 3) using new GPS data and a range-scale topographic, uplift, and denudation analysis of the presently aseismic Cascadia margin to constrain topographic/plate coupling relationships at this poorly understood margin.

Hydrogen-Deuterium Exchange Mass Spectrometry Reveals Calcium Binding Properties and Allosteric Regulation of Downstream Regulatory Element Antagonist Modulator (DREAM).

PubMed

Zhang, Jun; Li, Jing; Craig, Theodore A; Kumar, Rajiv; Gross, Michael L

2017-07-18

Downstream regulatory element antagonist modulator (DREAM) is an EF-hand Ca 2+ -binding protein that also binds to a specific DNA sequence, downstream regulatory elements (DRE), and thereby regulates transcription in a calcium-dependent fashion. DREAM binds to DRE in the absence of Ca 2+ but detaches from DRE under Ca 2+ stimulation, allowing gene expression. The Ca 2+ binding properties of DREAM and the consequences of the binding on protein structure are key to understanding the function of DREAM. Here we describe the application of hydrogen-deuterium exchange mass spectrometry (HDX-MS) and site-directed mutagenesis to investigate the Ca 2+ binding properties and the subsequent conformational changes of full-length DREAM. We demonstrate that all EF-hands undergo large conformation changes upon calcium binding even though the EF-1 hand is not capable of binding to Ca 2+ . Moreover, EF-2 is a lower-affinity site compared to EF-3 and -4 hands. Comparison of HDX profiles between wild-type DREAM and two EF-1 mutated constructs illustrates that the conformational changes in the EF-1 hand are induced by long-range structural interactions. HDX analyses also reveal a conformational change in an N-terminal leucine-charged residue-rich domain (LCD) remote from Ca 2+ -binding EF-hands. This LCD domain is responsible for the direct interaction between DREAM and cAMP response element-binding protein (CREB) and regulates the recruitment of the co-activator, CREB-binding protein. These long-range interactions strongly suggest how conformational changes transmit the Ca 2+ signal to CREB-mediated gene transcription.

Analysis of and reflection on bachelor thesis in nursing students: A descriptive study in Spain.

PubMed

Roca, Judith; Gros, Silvia; Canet, Olga

2018-06-11

The bachelor thesis, a final year subject to obtain a nursing degree, presents an ideal opportunity for the development and assessment of professional competencies. Thus, it is necessary to specify that the structure of the bachelor thesis works as an element of review and reflection from both a pedagogical and professional perspective. To analyse the main elements of the bachelor thesis in the nursing degree 2015-16 in Spain. A transversal descriptive study was conducted using a quantitative documentary analysis via study guides or grade reports. The variables were the main academic elements of the bachelor thesis subject (credits, competencies, learning outcomes, contents, methodologies, training activities and assessment). A probabilistic sample of 66 institutions was studied using descriptive statistics with statistical measures of central tendency and measures of variability. The results showed a maximum range of 12 and a minimum of 6 European Credit Transfer and Accumulation System. The definition and number of competencies to be developed varied and the learning outcomes were formulated in only 40.9% of the guides consulted. The most widely used teaching methodologies and training activities were academic supervision (87.9%) and autonomous work (80.3%). Regarding types of work, basic investigation (34.8%), care plans (33.3%) and literature review (30,3%) ranked highest. No specific descriptors could be linked to the contents. Finally, two main assessment tools were found: process and product. The rubric is presented as a main element of the assessment. The bachelor thesis is conceived as autonomous, personal and original academic work. But no homogeneity was observed in the key development elements such as competencies, teaching strategies, or type of bachelor thesis. Therefore, the findings from the analysis and the bibliographic review are presented as recommendations as regards the outcome, structure and/or teaching elements linked to the bachelor thesis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Accelerating atomic structure search with cluster regularization

NASA Astrophysics Data System (ADS)

Sørensen, K. H.; Jørgensen, M. S.; Bruix, A.; Hammer, B.

2018-06-01

We present a method for accelerating the global structure optimization of atomic compounds. The method is demonstrated to speed up the finding of the anatase TiO2(001)-(1 × 4) surface reconstruction within a density functional tight-binding theory framework using an evolutionary algorithm. As a key element of the method, we use unsupervised machine learning techniques to categorize atoms present in a diverse set of partially disordered surface structures into clusters of atoms having similar local atomic environments. Analysis of more than 1000 different structures shows that the total energy of the structures correlates with the summed distances of the atomic environments to their respective cluster centers in feature space, where the sum runs over all atoms in each structure. Our method is formulated as a gradient based minimization of this summed cluster distance for a given structure and alternates with a standard gradient based energy minimization. While the latter minimization ensures local relaxation within a given energy basin, the former enables escapes from meta-stable basins and hence increases the overall performance of the global optimization.

A Collaboration on Collaboration

NASA Technical Reports Server (NTRS)

Cobleigh, Brent

2004-01-01

NASA's 2003-2004 Leadership Development Program class recognized that effective collaborations are often the key to achieving mission success. Personal connections and common goals were key elements of their work together and key findings of their collaboration benchmarking within the agency.

Estrogen Receptor Folding Modulates cSrc Kinase SH2 Interaction via a Helical Binding Mode.

PubMed

Nieto, Lidia; Tharun, Inga M; Balk, Mark; Wienk, Hans; Boelens, Rolf; Ottmann, Christian; Milroy, Lech-Gustav; Brunsveld, Luc

2015-11-20

The estrogen receptors (ERs) feature, next to their transcriptional role, important nongenomic signaling actions, with emerging clinical relevance. The Src Homology 2 (SH2) domain mediated interaction between cSrc kinase and ER plays a key role in this; however the molecular determinants of this interaction have not been elucidated. Here, we used phosphorylated ER peptide and semisynthetic protein constructs in a combined biochemical and structural study to, for the first time, provide a quantitative and structural characterization of the cSrc SH2-ER interaction. Fluorescence polarization experiments delineated the SH2 binding motif in the ER sequence. Chemical shift perturbation analysis by nuclear magnetic resonance (NMR) together with molecular dynamics (MD) simulations allowed us to put forward a 3D model of the ER-SH2 interaction. The structural basis of this protein-protein interaction has been compared with that of the high affinity SH2 binding sequence GpYEEI. The ER features a different binding mode from that of the "two-pronged plug two-hole socket" model in the so-called specificity determining region. This alternative binding mode is modulated via the folding of ER helix 12, a structural element directly C-terminal of the key phosphorylated tyrosine. The present findings provide novel molecular entries for understanding nongenomic ER signaling and targeting the corresponding disease states.

Societal-Equity-Enhancing Criteria and Facility-Host Incentives Supporting Five Key Elements in the January 2012 Blue Ribbon Commission Report - 13015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eriksson, Leif G.; Dials, George E.; George, Critz H.

2013-07-01

In February 2009, the Obama Administration announced it would abandon USA's only candidate SNF/HLW-disposal facility since 1987. In 2010, all related activities were stopped and the Blue Ribbon Commission on America's Nuclear Future was established 'to recommend a new strategy for managing the back end of the nuclear fuel cycle', which it did in January 2012, emphasizing eight key elements. However, Key Element 1, 'A new, consent-based approach to siting future nuclear facilities', is qualitative/indeterminate rather than quantitative/measurable. It is thus highly-susceptible to semantic permutations that could extend rather than, as intended, expedite the siting of future nuclear facilities unlessmore » it also defines: a) Whose consent is needed?; and b) What constitutes consent? The following 'generic', radiation-risk- and societal-equity-based criteria address these questions: 1. Identify areas affected by projected radiation and other health risks from: a. The proposed nuclear facility (facility stakeholders); and b. The related nuclear-materials-transportation routes (transportation stakeholders); then 2. Surround each stakeholder area with a buffer zone and use this enlarged foot print to identify: a. Stakeholder hosts; and b. Areas not hosting any stakeholder category (interested parties). 3. Define 'consent-based' as being at least 60 percent of the 'population' in the respective stakeholder category and apply this yardstick to both 'in favor' and 'against' votes. Although criteria 1 and 2 also need facility-based definitions to make Key Element 1 measurable, the described siting approach, augmented by related facility-host incentives, would expedite the schedule and reduce the cost for achieving Key Elements 4-6 and 8, politics permitting. (authors)« less

Free-Suspension Residual Flexibility Testing of Space Station Pathfinder: Comparison to Fixed-Base Results

NASA Technical Reports Server (NTRS)

Tinker, Michael L.

1998-01-01

Application of the free-suspension residual flexibility modal test method to the International Space Station Pathfinder structure is described. The Pathfinder, a large structure of the general size and weight of Space Station module elements, was also tested in a large fixed-base fixture to simulate Shuttle Orbiter payload constraints. After correlation of the Pathfinder finite element model to residual flexibility test data, the model was coupled to a fixture model, and constrained modes and frequencies were compared to fixed-base test. modes. The residual flexibility model compared very favorably to results of the fixed-base test. This is the first known direct comparison of free-suspension residual flexibility and fixed-base test results for a large structure. The model correlation approach used by the author for residual flexibility data is presented. Frequency response functions (FRF) for the regions of the structure that interface with the environment (a test fixture or another structure) are shown to be the primary tools for model correlation that distinguish or characterize the residual flexibility approach. A number of critical issues related to use of the structure interface FRF for correlating the model are then identified and discussed, including (1) the requirement of prominent stiffness lines, (2) overcoming problems with measurement noise which makes the antiresonances or minima in the functions difficult to identify, and (3) the use of interface stiffness and lumped mass perturbations to bring the analytical responses into agreement with test data. It is shown that good comparison of analytical-to-experimental FRF is the key to obtaining good agreement of the residual flexibility values.

Voluntary medical male circumcision: a qualitative study exploring the challenges of costing demand creation in eastern and southern Africa.

PubMed

Bertrand, Jane T; Njeuhmeli, Emmanuel; Forsythe, Steven; Mattison, Sarah K; Mahler, Hally; Hankins, Catherine A

2011-01-01

This paper proposes an approach to estimating the costs of demand creation for voluntary medical male circumcision (VMMC) scale-up in 13 countries of eastern and southern Africa. It addresses two key questions: (1) what are the elements of a standardized package for demand creation? And (2) what challenges exist and must be taken into account in estimating the costs of demand creation? We conducted a key informant study on VMMC demand creation using purposive sampling to recruit seven people who provide technical assistance to government programs and manage budgets for VMMC demand creation. Key informants provided their views on the important elements of VMMC demand creation and the most effective funding allocations across different types of communication approaches (e.g., mass media, small media, outreach/mobilization). The key finding was the wide range of views, suggesting that a standard package of core demand creation elements would not be universally applicable. This underscored the importance of tailoring demand creation strategies and estimates to specific country contexts before estimating costs. The key informant interviews, supplemented by the researchers' field experience, identified these issues to be addressed in future costing exercises: variations in the cost of VMMC demand creation activities by country and program, decisions about the quality and comprehensiveness of programming, and lack of data on critical elements needed to "trigger the decision" among eligible men. Based on this study's findings, we propose a seven-step methodological approach to estimate the cost of VMMC scale-up in a priority country, based on our key assumptions. However, further work is needed to better understand core components of a demand creation package and how to cost them. Notwithstanding the methodological challenges, estimating the cost of demand creation remains an essential element in deriving estimates of the total costs for VMMC scale-up in eastern and southern Africa.

Voluntary Medical Male Circumcision: A Qualitative Study Exploring the Challenges of Costing Demand Creation in Eastern and Southern Africa

PubMed Central

Bertrand, Jane T.; Njeuhmeli, Emmanuel; Forsythe, Steven; Mattison, Sarah K.; Mahler, Hally; Hankins, Catherine A.

2011-01-01

Background This paper proposes an approach to estimating the costs of demand creation for voluntary medical male circumcision (VMMC) scale-up in 13 countries of eastern and southern Africa. It addresses two key questions: (1) what are the elements of a standardized package for demand creation? And (2) what challenges exist and must be taken into account in estimating the costs of demand creation? Methods and Findings We conducted a key informant study on VMMC demand creation using purposive sampling to recruit seven people who provide technical assistance to government programs and manage budgets for VMMC demand creation. Key informants provided their views on the important elements of VMMC demand creation and the most effective funding allocations across different types of communication approaches (e.g., mass media, small media, outreach/mobilization). The key finding was the wide range of views, suggesting that a standard package of core demand creation elements would not be universally applicable. This underscored the importance of tailoring demand creation strategies and estimates to specific country contexts before estimating costs. The key informant interviews, supplemented by the researchers' field experience, identified these issues to be addressed in future costing exercises: variations in the cost of VMMC demand creation activities by country and program, decisions about the quality and comprehensiveness of programming, and lack of data on critical elements needed to “trigger the decision” among eligible men. Conclusions Based on this study's findings, we propose a seven-step methodological approach to estimate the cost of VMMC scale-up in a priority country, based on our key assumptions. However, further work is needed to better understand core components of a demand creation package and how to cost them. Notwithstanding the methodological challenges, estimating the cost of demand creation remains an essential element in deriving estimates of the total costs for VMMC scale-up in eastern and southern Africa. PMID:22140450

Comparison of SP-LIBS and DP-LIBS on metal and non-metal testing based on LIBS

NASA Astrophysics Data System (ADS)

Lin, Xiaomei; Sun, Haoran; Lin, Jingjun

2017-10-01

Laser-induced breakdown spectroscopy (LIBS) technology for metal and nonmetallic detection accuracy is the key technology to be solved in LIBS measurement, Due to metal elements and non-metallic elements in the lively, atomic structure and the degree of excitation of the laser are totally different, so the laser induced plasma evolution and spectral intensity are absolutely different. Among the many factors that affect measurement accuracy, the single and double pulse of the laser has a great influence on the measurement accuracy of metal and non-metal, they both have their own advantages, but also have their own shortcomings. In order to compare the effect of SP-LIBS and DP-LIBS on the measurement results of different elements, in this experiment, we put the metal element aluminum and non-metallic element carbon as the sample, the laser energy as a variable, using the high-speed camera shooting SP- LIBS and DP- LIBS plasma images. Using the spectral analyzer to record the spectral intensity of the elements, by calculating the relative RSD of the signal intensity and comparing the spectral intensity and the signal stability for different elements, develop an optimized experimental program. The experimental results show that under the same energy condition, the metal aluminum ion image under the DP- LIBS and the non-metallic carbon ion image under the SP- LIBS are the most suitable images. By considering the stability of the line intensity and the signal stability, we find that the sensitivity and stability of the signal strength of the metal elements under the double pulse are better than that of the single pulse, and for the non-metallic element, the single pulse laser is better than the double pulse.

Platinum Partitioning at Low Oxygen Fugacity: Implications for Core Formation Processes

NASA Technical Reports Server (NTRS)

Medard, E.; Martin, A. M.; Righter, K.; Lanziroti, A.; Newville, M.

2016-01-01

Highly siderophile elements (HSE = Au, Re, and the Pt-group elements) are tracers of silicate / metal interactions during planetary processes. Since most core-formation models involve some state of equilibrium between liquid silicate and liquid metal, understanding the partioning of highly siderophile elements (HSE) between silicate and metallic melts is a key issue for models of core / mantle equilibria and for core formation scenarios. However, partitioning models for HSE are still inaccurate due to the lack of sufficient experimental constraints to describe the variations of partitioning with key variable like temperature, pressure, and oxygen fugacity. In this abstract, we describe a self-consistent set of experiments aimed at determining the valence of platinum, one of the HSE, in silicate melts. This is a key information required to parameterize the evolution of platinum partitioning with oxygen fugacity.

Assessment of Carrying Capacity of Timber Element Using SBRA Method

NASA Astrophysics Data System (ADS)

Kraus, Michal

2017-10-01

Wood as a building material has a significant perspective in the context of nonrenewable energy sources and production of greenhouse gas emissions. The subject of this paper is to verify the carrying capacity of the timber element using the probabilistic method Simulation Based Reliability Assessment (SBRA). The simulation is performed for one million cycles. Key factors decreasing the strength of wooden material at the time include the duration of the loads, and combinations thereof. Inconsiderable factor affecting the strength of wood is also the humidity. Continuous beam with three fields (length 15 m, glued laminated timber, and strength class GL 36 according to the DIN EN 1194) is placed in an environment with a thermal-humidity regime of the 2nd class according to the EC 5. Average life of carrying timber structure is estimated to be 50 years. The simulation results show that there is no risk of failure of wood during the first year. The probability of failure is common in the 10 years of its life. Then, wooden element already meets only a reduced level of reliability.

Gene transfer strategies in animal transgenesis.

PubMed

Montoliu, Lluís

2002-01-01

Position effects in animal transgenesis have prevented the reproducible success and limited the initial expectations of this technique in many biotechnological projects. Historically, several strategies have been devised to overcome such position effects, including the progressive addition of regulatory elements belonging to the same or to a heterologous expression domain. An expression domain is thought to contain all regulatory elements that are needed to specifically control the expression of a given gene in time and space. The lack of profound knowledge on the chromatin structure of expression domains of biotechnological interest, such as mammary gland-specific genes, explains why most standard expression vectors have failed to drive high-level, position-independent, and copy-number-dependent expression of transgenes in a reproducible manner. In contrast, the application of artificial chromosome-type constructs to animal transgenesis usually ensures optimal expression levels. YACs, BACs, and PACs have become crucial tools in animal transgenesis, allowing the inclusion of distant key regulatory sequences, previously unknown, that are characteristic for each expression domain. These elements contribute to insulating the artificial chromosome-type constructs from chromosomal position effects and are fundamental in order to guarantee the correct expression of transgenes.

POMM: design of rotating mechanism and hexapod structure

NASA Astrophysics Data System (ADS)

Côté, Patrice; Leclerc, Mélanie; Demers, Mathieu; Bastien, Pierre; Hernandez, Olivier

2014-08-01

The new high precision polarimeter for the "Observatoire du Mont Mégantic" (POMM) is an instrument designed to observe exoplanets and other targets in the visible and near infrared wavebands. The requirements to achieve these observation goals are posing unusual challenges to structural and mechanical designers. In this paper, the detailed design, analysis and laboratory results of the key mechanical structure and sub-systems are presented. First, to study extremely low polarization, the birefringence effect due to stresses in the optical elements must be kept to the lowest possible values. The double-wedge Wollaston custom prism assembly that splits the incoming optical beam is made of bonded α-BBO to N-BK-7 glass lenses. Because of the large mismatch of coefficients of thermal expansion and temperatures as low as -40°C that can be encountered at Mont-Mégantic observatory, a finite element analysis (FEA) model is developed to find the best adhesive system to minimize stresses. Another critical aspect discussed in details is the implementation of the cascaded rotating elements and the twin rotating stages. Special attention is given to the drive mechanism and encoding technology. The objective was to reach high absolute positional accuracy in rotation without any mechanical backlash. As for many other instruments, mass, size and dimensional stability are important critera for the supporting structure. For a cantilevered device, such as POMM, a static hexapod is an attractive solution because of the high stiffness to weight ratio. However, the mechanical analysis revealed that the specific geometry of the dual channel optical layout also added an off-axis counterbalancing problem. To reach an X-Y displacement error on the detector smaller than 35μm for 0-45° zenith angle, further structural optimization was done using FEA. An imaging camera was placed at the detector plane during assembly to measure the actual optical beam shift under varying gravitational loading.

47 CFR 51.509 - Rate structure standards for specific elements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 3 2014-10-01 2014-10-01 false Rate structure standards for specific elements... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.509 Rate structure standards for specific elements. In addition to the general rules set forth in § 51.507, rates for specific elements shall comply...

47 CFR 51.509 - Rate structure standards for specific elements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 3 2012-10-01 2012-10-01 false Rate structure standards for specific elements... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.509 Rate structure standards for specific elements. In addition to the general rules set forth in § 51.507, rates for specific elements shall comply...

47 CFR 51.509 - Rate structure standards for specific elements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Rate structure standards for specific elements... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.509 Rate structure standards for specific elements. In addition to the general rules set forth in § 51.507, rates for specific elements shall comply...

47 CFR 51.509 - Rate structure standards for specific elements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 3 2011-10-01 2011-10-01 false Rate structure standards for specific elements... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.509 Rate structure standards for specific elements. In addition to the general rules set forth in § 51.507, rates for specific elements shall comply...

47 CFR 51.509 - Rate structure standards for specific elements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 3 2013-10-01 2013-10-01 false Rate structure standards for specific elements... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.509 Rate structure standards for specific elements. In addition to the general rules set forth in § 51.507, rates for specific elements shall comply...

Fine-tuning key parameters of an integrated reactor system for the simultaneous removal of COD, sulfate and ammonium and elemental sulfur reclamation.

PubMed

Yuan, Ye; Chen, Chuan; Liang, Bin; Huang, Cong; Zhao, Youkang; Xu, Xijun; Tan, Wenbo; Zhou, Xu; Gao, Shuang; Sun, Dezhi; Lee, Duujong; Zhou, Jizhong; Wang, Aijie

2014-03-30

In this paper, we proposed an integrated reactor system for simultaneous removal of COD, sulfate and ammonium (integrated C-S-N removal system) and investigated the key parameters of the system for a high level of elemental sulfur (S(0)) production. The system consisted of 4 main units: sulfate reduction and organic carbon removal (SR-CR), autotrophic and heterotrophic denitrifying sulfide removal (A&H-DSR), sulfur reclamation (SR), and aerated filter for aerobic nitrification (AN). In the system, the effects of key operational parameters on production of elemental sulfur were investigated, including hydraulic retention time (HRT) of each unit, sulfide/nitrate (S(2-)-S/NO3(-)-N) ratios, reflux ratios between the A&H-DSR and AN units, and loading rates of chemical oxygen demand (COD), sulfate and ammonium. Physico-chemical characteristics of biosulfur were studied for acquiring efficient S(0) recovery. The experiments successfully explored the optimum parameters for each unit and demonstrated 98% COD, 98% sulfate and 78% nitrogen removal efficiency. The optimum HRTs for SR-CR, A&H-DSR and AN were 12h, 3h and 3h, respectively. The reflux ratio of 3 could provide adequate S(2-)-S/NO3(-)-N ratio (approximately 1:1) to the A&H-DSR unit for obtaining maximum sulfur production. In this system, the maximum production of S(0) reached 90%, but only 60% S(0) was reclaimed from effluent. The S(0) that adhered to the outer layer of granules was deposited in the bottom of the A&H-DSR unit. Finally, the microbial community structure of the corresponding unit at different operational stage were analyzed by 16S rRNA gene based high throughput Illumina MiSeq sequencing and the potential function of dominant species were discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Cations Stiffen Actin Filaments by Adhering a Key Structural Element to Adjacent Subunits

PubMed Central

2016-01-01

Ions regulate the assembly and mechanical properties of actin filaments. Recent work using structural bioinformatics and site-specific mutagenesis favors the existence of two discrete and specific divalent cation binding sites on actin filaments, positioned in the long axis between actin subunits. Cation binding at one site drives polymerization, while the other modulates filament stiffness and plays a role in filament severing by the regulatory protein, cofilin. Existing structural methods have not been able to resolve filament-associated cations, and so in this work we turn to molecular dynamics simulations to suggest a candidate binding pocket geometry for each site and to elucidate the mechanism by which occupancy of the “stiffness site” affects filament mechanical properties. Incorporating a magnesium ion in the “polymerization site” does not seem to require any large-scale change to an actin subunit’s conformation. Binding of a magnesium ion in the “stiffness site” adheres the actin DNase-binding loop (D-loop) to its long-axis neighbor, which increases the filament torsional stiffness and bending persistence length. Our analysis shows that bound D-loops occupy a smaller region of accessible conformational space. Cation occupancy buries key conserved residues of the D-loop, restricting accessibility to regulatory proteins and enzymes that target these amino acids. PMID:27146246

Implanted neural network potentials: Application to Li-Si alloys

NASA Astrophysics Data System (ADS)

Onat, Berk; Cubuk, Ekin D.; Malone, Brad D.; Kaxiras, Efthimios

2018-03-01

Modeling the behavior of materials composed of elements with different bonding and electronic structure character for large spatial and temporal scales and over a large compositional range is a challenging problem. Cases in point are amorphous alloys of Si, a prototypical covalent material, and Li, a prototypical metal, which are being considered as anodes for high-energy-density batteries. To address this challenge, we develop a methodology based on neural networks that extends the conventional training approach to incorporate pre-trained parts that capture the character of different components, into the overall network; we refer to this model as the "implanted neural network" method. We show that this approach works well for the Si-Li amorphous alloys for a wide range of compositions, giving good results for key quantities like the diffusion coefficients. The method is readily generalizable to more complicated situations that involve two or more different elements.

LACIE performance predictor FOC users manual

NASA Technical Reports Server (NTRS)

1976-01-01

The LACIE Performance Predictor (LPP) is a computer simulation of the LACIE process for predicting worldwide wheat production. The simulation provides for the introduction of various errors into the system and provides estimates based on these errors, thus allowing the user to determine the impact of selected error sources. The FOC LPP simulates the acquisition of the sample segment data by the LANDSAT Satellite (DAPTS), the classification of the agricultural area within the sample segment (CAMS), the estimation of the wheat yield (YES), and the production estimation and aggregation (CAS). These elements include data acquisition characteristics, environmental conditions, classification algorithms, the LACIE aggregation and data adjustment procedures. The operational structure for simulating these elements consists of the following key programs: (1) LACIE Utility Maintenance Process, (2) System Error Executive, (3) Ephemeris Generator, (4) Access Generator, (5) Acquisition Selector, (6) LACIE Error Model (LEM), and (7) Post Processor.

Design of a Thermal Precipitator for the Characterization of Smoke Particles from Common Spacecraft Materials

NASA Technical Reports Server (NTRS)

Meyer, Marit Elisabeth

2015-01-01

A thermal precipitator (TP) was designed to collect smoke aerosol particles for microscopic analysis in fire characterization research. Information on particle morphology, size and agglomerate structure obtained from these tests supplements additional aerosol data collected. Modeling of the thermal precipitator throughout the design process was performed with the COMSOL Multiphysics finite element software package, including the Eulerian flow field and thermal gradients in the fluid. The COMSOL Particle Tracing Module was subsequently used to determine particle deposition. Modeling provided optimized design parameters such as geometry, flow rate and temperatures. The thermal precipitator was built and testing verified the performance of the first iteration of the device. The thermal precipitator was successfully operated and provided quality particle samples for microscopic analysis, which furthered the body of knowledge on smoke particulates. This information is a key element of smoke characterization and will be useful for future spacecraft fire detection research.

Exobiology: The NASA program

NASA Technical Reports Server (NTRS)

Rummel, John D.; Harper, Lynn; Andersen, Dale

1992-01-01

The goal of NASA's Exobiology Program is to understand the origin, evolution, and distribution of life in the universe. To do this, the Exobiology Program seeks to provide a critical framework and some key research to allow NASA to bear the combined talents and capabilities of the agency and the scientific community, and the unique opportunities afforded by space exploration. To provide structure and direction to the quest for answers, the Exobiology Program has instituted a comprehensive research program divided into four elements which are being implemented at several of NASA's research centers and in the university community. These program elements correspond to the four major epochs in the evolution of living systems: (1) cosmic evolution of the biogenic compounds; (2) prebiotic evolution; (3) origin and early evolution of life; and (4) evolution of advanced life. The overall research program is designed to trace the pathways leading from the origin of the universe through the major epochs in the story of life.

Extensive gene content variation in the Brachypodium distachyon pan-genome correlates with population structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, Sean P.; Contreras-Moreira, Bruno; Woods, Daniel P.

While prokaryotic pan-genomes have been shown to contain many more genes than any individual organism, the prevalence and functional significance of differentially present genes in eukaryotes remains poorly understood. Whole-genome de novo assembly and annotation of 54 lines of the grass Brachypodium distachyon yield a pan-genome containing nearly twice the number of genes found in any individual genome. Genes present in all lines are enriched for essential biological functions, while genes present in only some lines are enriched for conditionally beneficial functions (e.g., defense and development), display faster evolutionary rates, lie closer to transposable elements and are less likely tomore » be syntenic with orthologous genes in other grasses. Our data suggest that differentially present genes contribute substantially to phenotypic variation within a eukaryote species, these genes have a major influence in population genetics, and transposable elements play a key role in pan-genome evolution.« less

VEGA Launch Vehicle: VV02 Flight Campaign Thermal Analysis

NASA Astrophysics Data System (ADS)

Moroni, D.; Perugini, P.; Mancini, R.; Bonnet, M.

2014-06-01

A reliable tool for the prediction of temperature trends vs. time during the operative timeline of a launcher represents one of the key elements for the qualification of a launch vehicle itself.The correct evaluation of the thermal behaviour during the mission, both for the launcher elements (structures, electronic items, tanks, motors...) and for the Payloads carried by the same Launcher, is one of the preliminary activities to be performed before a flight campaign.For such scope AVIO constructed a Thermal Mathematical Model (TMM) by means of the ESA software "ESATAN Thermal Modelling Suite (TMS)" [1] used for the prediction of the temperature trends both on VV01 (VEGA LV Qualification Flight) and VV02 (First VEGA LV commercial flight) with successfully results in terms of post-flight comparison with the sensor data outputs.Aim of this paper is to show the correlation obtained by AVIO VEGA LV SYS TMM in the frame of VV02 Flight.

Extensive gene content variation in the Brachypodium distachyon pan-genome correlates with population structure.

PubMed

Gordon, Sean P; Contreras-Moreira, Bruno; Woods, Daniel P; Des Marais, David L; Burgess, Diane; Shu, Shengqiang; Stritt, Christoph; Roulin, Anne C; Schackwitz, Wendy; Tyler, Ludmila; Martin, Joel; Lipzen, Anna; Dochy, Niklas; Phillips, Jeremy; Barry, Kerrie; Geuten, Koen; Budak, Hikmet; Juenger, Thomas E; Amasino, Richard; Caicedo, Ana L; Goodstein, David; Davidson, Patrick; Mur, Luis A J; Figueroa, Melania; Freeling, Michael; Catalan, Pilar; Vogel, John P

2017-12-19

While prokaryotic pan-genomes have been shown to contain many more genes than any individual organism, the prevalence and functional significance of differentially present genes in eukaryotes remains poorly understood. Whole-genome de novo assembly and annotation of 54 lines of the grass Brachypodium distachyon yield a pan-genome containing nearly twice the number of genes found in any individual genome. Genes present in all lines are enriched for essential biological functions, while genes present in only some lines are enriched for conditionally beneficial functions (e.g., defense and development), display faster evolutionary rates, lie closer to transposable elements and are less likely to be syntenic with orthologous genes in other grasses. Our data suggest that differentially present genes contribute substantially to phenotypic variation within a eukaryote species, these genes have a major influence in population genetics, and transposable elements play a key role in pan-genome evolution.

Research and technology

NASA Technical Reports Server (NTRS)

1990-01-01

As the NASA center responsible for assembly, checkout, servicing, launch, recovery, and operational support of Space Transportation System elements and payloads, Kennedy Space Center (KSC) is placing increasing emphasis on KSC's research and technology program. In addition to strengthening those areas of engineering and operations technology that contribute to safer, more efficient, and more economical execution of the current mission, the technological tools needed to execute KSC's mission relative to future programs are being developed. The Engineering Development Directorate encompasses most of the laboratories and other KSC resources that are key elements of research and technology program implementation and is responsible for implementation of the majority of the projects in this KSC 1990 annual report. Projects under the following topics are covered: (1) materials science; (2) hazardous emissions and contamination monitoring; (3) biosciences; (4) autonomous systems; (5) communications and control; (6) meteorology; (7) technology utilization; and (8) mechanics, structures, and cryogenics.

Cooperative polymerization of α-helices induced by macromolecular architecture

NASA Astrophysics Data System (ADS)

Baumgartner, Ryan; Fu, Hailin; Song, Ziyuan; Lin, Yao; Cheng, Jianjun

2017-07-01

Catalysis observed in enzymatic processes and protein polymerizations often relies on the use of supramolecular interactions and the organization of functional elements in order to gain control over the spatial and temporal elements of fundamental cellular processes. Harnessing these cooperative interactions to catalyse reactions in synthetic systems, however, remains challenging due to the difficulty in creating structurally controlled macromolecules. Here, we report a polypeptide-based macromolecule with spatially organized α-helices that can catalyse its own formation. The system consists of a linear polymeric scaffold containing a high density of initiating groups from which polypeptides are grown, forming a brush polymer. The folding of polypeptide side chains into α-helices dramatically enhances the polymerization rate due to cooperative interactions of macrodipoles between neighbouring α-helices. The parameters that affect the rate are elucidated by a two-stage kinetic model using principles from nucleation-controlled protein polymerizations; the key difference being the irreversible nature of this polymerization.

Creating an institutional resource for research education and career development: a novel model from Oregon Clinical and Translational Research Institute.

PubMed

Morris, Cynthia D; McCracken, Karen; Samuels, Mary; Orwoll, Eric

2014-06-01

We have created an education and career development program within the CTSA structure at OHSU that serves the entire institution. We believe that this is unusual in scope among CTSA programs and has contributed to an increase in career development funding and research skills among fellows and faculty. While the key element is the institutional scope, important elements include: Tailoring programs of emphasis to points of inflection on the career pathway. Minimizing barriers to education by creating a flexible, tuition-free program. An integrated one-stop education and career development approach. An institutional program for career development award applicants as well as recipients. This career development program was developed within the context of a midsize health science university but the overall strategy may be applied to other CTSAs to simplify and reduce costs of education program development.

Extensive gene content variation in the Brachypodium distachyon pan-genome correlates with population structure

DOE PAGES

Gordon, Sean P.; Contreras-Moreira, Bruno; Woods, Daniel P.; ...

2017-12-19

While prokaryotic pan-genomes have been shown to contain many more genes than any individual organism, the prevalence and functional significance of differentially present genes in eukaryotes remains poorly understood. Whole-genome de novo assembly and annotation of 54 lines of the grass Brachypodium distachyon yield a pan-genome containing nearly twice the number of genes found in any individual genome. Genes present in all lines are enriched for essential biological functions, while genes present in only some lines are enriched for conditionally beneficial functions (e.g., defense and development), display faster evolutionary rates, lie closer to transposable elements and are less likely tomore » be syntenic with orthologous genes in other grasses. Our data suggest that differentially present genes contribute substantially to phenotypic variation within a eukaryote species, these genes have a major influence in population genetics, and transposable elements play a key role in pan-genome evolution.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Hongyi; Li, Yang; Zeng, Danielle

Process integration and optimization is the key enabler of the Integrated Computational Materials Engineering (ICME) of carbon fiber composites. In this paper, automated workflows are developed for two types of composites: Sheet Molding Compounds (SMC) short fiber composites, and multi-layer unidirectional (UD) composites. For SMC, the proposed workflow integrates material processing simulation, microstructure representation volume element (RVE) models, material property prediction and structure preformation simulation to enable multiscale, multidisciplinary analysis and design. Processing parameters, microstructure parameters and vehicle subframe geometry parameters are defined as the design variables; the stiffness and weight of the structure are defined as the responses. Formore » multi-layer UD structure, this work focuses on the discussion of different design representation methods and their impacts on the optimization performance. Challenges in ICME process integration and optimization are also summarized and highlighted. Two case studies are conducted to demonstrate the integrated process and its application in optimization.« less

From lignin association to nano-/micro-particle preparation: Extracting higher value of lignin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Wenwen; Simmons, Blake; Singh, Seema

As the most abundant source of renewable aromatic compounds on the planet, lignin is gaining growing interest in replacing petroleum-based chemicals and products. Value-added applications of lignin are also essential for economic viability for future bio-refineries. It is however an under-utilized natural resource due to its structural heterogeneities. Lignin nanoparticles offer many opportunities for value-added applications of lignin. The solution structures of lignin were proposed as one of the key elements in controlling lignin nano-/micro-particle preparation. Fundamental understanding of solutionstructures of lignin aid in designing better fabrication of lignin nanoparticles. A deeper understanding of the observed experimental results also pointsmore » to the need for detailed studies of lignin in solution. Lastly, this review consists of two major topics, the solution structures of lignin and lignin nano-/micro-particle preparation. Suggestions for future studies regarding these two topics were also put forward.« less

From lignin association to nano-/micro-particle preparation: Extracting higher value of lignin

DOE PAGES

Zhao, Wenwen; Simmons, Blake; Singh, Seema; ...

2016-09-26

As the most abundant source of renewable aromatic compounds on the planet, lignin is gaining growing interest in replacing petroleum-based chemicals and products. Value-added applications of lignin are also essential for economic viability for future bio-refineries. It is however an under-utilized natural resource due to its structural heterogeneities. Lignin nanoparticles offer many opportunities for value-added applications of lignin. The solution structures of lignin were proposed as one of the key elements in controlling lignin nano-/micro-particle preparation. Fundamental understanding of solutionstructures of lignin aid in designing better fabrication of lignin nanoparticles. A deeper understanding of the observed experimental results also pointsmore » to the need for detailed studies of lignin in solution. Lastly, this review consists of two major topics, the solution structures of lignin and lignin nano-/micro-particle preparation. Suggestions for future studies regarding these two topics were also put forward.« less

Structures of Neural Correlation and How They Favor Coding

PubMed Central

Franke, Felix; Fiscella, Michele; Sevelev, Maksim; Roska, Botond; Hierlemann, Andreas; da Silveira, Rava Azeredo

2017-01-01

Summary The neural representation of information suffers from “noise”—the trial-to-trial variability in the response of neurons. The impact of correlated noise upon population coding has been debated, but a direct connection between theory and experiment remains tenuous. Here, we substantiate this connection and propose a refined theoretical picture. Using simultaneous recordings from a population of direction-selective retinal ganglion cells, we demonstrate that coding benefits from noise correlations. The effect is appreciable already in small populations, yet it is a collective phenomenon. Furthermore, the stimulus-dependent structure of correlation is key. We develop simple functional models that capture the stimulus-dependent statistics. We then use them to quantify the performance of population coding, which depends upon interplays of feature sensitivities and noise correlations in the population. Because favorable structures of correlation emerge robustly in circuits with noisy, nonlinear elements, they will arise and benefit coding beyond the confines of retina. PMID:26796692

Vertical organic transistors.

PubMed

Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

2015-11-11

Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

A Roof for the Lions' House

NASA Technical Reports Server (NTRS)

1978-01-01

Fans of the National Football League s Detroit Lions don't worry about game day weather. Their magnificent new Pontiac Stadium has a domed, air-supported, fabric roof that admits light but protects the playing field and patrons from the elements. The 80,000-seat Silverdome is the world s largest fabric-covered structure-and aerospace technology played an important part in its construction. The key to economical construction of the Silverdome--and many other types of buildings--is a spinoff of fiber glass Beta yarn coated with Teflon TFE fluorocarbon resin. The big advance it offers is permanency.The team of DuPont, Chemical Fabrics and Birdair have collaborated on a number of fabric structures. Some are supported by air pressure, others by cables alone. Most of the structures are in the recreational category. With conventional construction costs still on the upswing, you're likely to see a great many more permanent facilities enclosed by the aerospace spinoff fabric.

Nuclear Mechanics in Disease

PubMed Central

Zwerger, Monika; Ho, Chin Yee; Lammerding, Jan

2015-01-01

Over the past two decades, the biomechanical properties of cells have emerged as key players in a broad range of cellular functions, including migration, proliferation, and differentiation. Although much of the attention has focused on the cytoskeletal networks and the cell’s microenvironment, relatively little is known about the contribution of the cell nucleus. Here, we present an overview of the structural elements that determine the physical properties of the nucleus and discuss how changes in the expression of nuclear components or mutations in nuclear proteins can affect not only nuclear mechanics but also modulate cytoskeletal organization and diverse cellular functions. These findings illustrate that the nucleus is tightly integrated into the surrounding cellular structure. Consequently, changes in nuclear structure and composition are highly relevant to normal development and physiology and can contribute to many human diseases, such as muscular dystrophy, dilated cardiomyopathy, (premature) aging, and cancer. PMID:21756143

The flavivirus capsid protein: Structure, function and perspectives towards drug design.

PubMed

Oliveira, Edson R A; Mohana-Borges, Ronaldo; de Alencastro, Ricardo B; Horta, Bruno A C

2017-01-02

Flaviviruses, such as dengue and zika viruses, are etiologic agents transmitted to humans mainly by arthropods and are of great epidemiological interest. The flavivirus capsid protein is a structural element required for the viral nucleocapsid assembly that presents the classical function of sheltering the viral genome. After decades of research, many reports have shown its different functionalities and influence over cell normal functioning. The subcellular distribution of this protein, which involves accumulation around lipid droplets and nuclear localization, also corroborates with its multi-functional characteristic. As flavivirus diseases are still in need of global control and in view of the possible key functionalities that the capsid protein promotes over flavivirus biology, novel considerations arise towards anti-flavivirus drug research. This review covers the main aspects concerning structural and functional features of the flavivirus C protein, ultimately, highlighting prospects in drug discovery based on this viral target. Copyright © 2016 Elsevier B.V. All rights reserved.

Computational Aerothermodynamic Simulation Issues on Unstructured Grids

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; White, Jeffery A.

2004-01-01

The synthesis of physical models for gas chemistry and turbulence from the structured grid codes LAURA and VULCAN into the unstructured grid code FUN3D is described. A directionally Symmetric, Total Variation Diminishing (STVD) algorithm and an entropy fix (eigenvalue limiter) keyed to local cell Reynolds number are introduced to improve solution quality for hypersonic aeroheating applications. A simple grid-adaptation procedure is incorporated within the flow solver. Simulations of flow over an ellipsoid (perfect gas, inviscid), Shuttle Orbiter (viscous, chemical nonequilibrium) and comparisons to the structured grid solvers LAURA (cylinder, Shuttle Orbiter) and VULCAN (flat plate) are presented to show current capabilities. The quality of heating in 3D stagnation regions is very sensitive to algorithm options in general, high aspect ratio tetrahedral elements complicate the simulation of high Reynolds number, viscous flow as compared to locally structured meshes aligned with the flow.

The Virginia pharmacy practice transformation conference: outcomes and next steps.

PubMed

Silvester, Janet A

2012-04-01

Thought leaders in Virginia came together to achieve consensus on the pharmacy practice innovations required to advance the medication-related health outcomes of patients in the Commonwealth. The participants identified key elements and strategies needed for practice transformation and these became the foundation for practice change. The primary key elements included legislation and regulation modifications, payment reform, and business model development. The Virginia Pharmacy Congress, which represents key pharmacy stakeholders in the Commonwealth, became the home for the transformation movement and the development and implementation of a unified action plan for achieving the envisioned practice transformation.

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data [plus Supplementary Electronic Annex 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolery, Thomas J.; Jove Colon, Carlos F.

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data.more » Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO 2, water, and aqueous species such as Na + and Cl -. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of “links” to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare “key” or “reference” datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.« less

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data [plus Supplementary Electronic Annex 2

DOE PAGES

Wolery, Thomas J.; Jove Colon, Carlos F.

2016-09-26

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data.more » Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO 2, water, and aqueous species such as Na + and Cl -. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of “links” to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare “key” or “reference” datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.« less

“Even our Dairy Queen shut down”: Risk and resilience in bioenergy development in forest-dependent communities in the US South

Treesearch

Sarah Hitchner; John Schelhas; J. Peter Brosius

2017-01-01

Wood-based bioenergy in the US South is a key element in a sociotechnical imaginary that brings together rural development, energy independence, and environmental sustainability; it is also a key element in another imaginary in which powerful interest groups from the private sector and government collude in ways that enrich them regardless of success of the endeavor,...

RNA structure in splicing: An evolutionary perspective.

PubMed

Lin, Chien-Ling; Taggart, Allison J; Fairbrother, William G

2016-09-01

Pre-mRNA splicing is a key post-transcriptional regulation process in which introns are excised and exons are ligated together. A novel class of structured intron was recently discovered in fish. Simple expansions of complementary AC and GT dimers at opposite boundaries of an intron were found to form a bridging structure, thereby enforcing correct splice site pairing across the intron. In some fish introns, the RNA structures are strong enough to bypass the need of regulatory protein factors for splicing. Here, we discuss the prevalence and potential functions of highly structured introns. In humans, structured introns usually arise through the co-occurrence of C and G-rich repeats at intron boundaries. We explore the potentially instructive example of the HLA receptor genes. In HLA pre-mRNA, structured introns flank the exons that encode the highly polymorphic β sheet cleft, making the processing of the transcript robust to variants that disrupt splicing factor binding. While selective forces that have shaped HLA receptor are fairly atypical, numerous other highly polymorphic genes that encode receptors contain structured introns. Finally, we discuss how the elevated mutation rate associated with the simple repeats that often compose structured intron can make structured introns themselves rapidly evolving elements.

Finite element normal mode analysis of resistance welding jointed of dissimilar plate hat structure

NASA Astrophysics Data System (ADS)

Nazri, N. A.; Sani, M. S. M.

2017-10-01

Structural joints offer connection between structural element (beam, plate, solid etc.) in order to build a whole assembled structure. The complex behaviour of connecting elements plays a valuable role in characteristics of dynamic such as natural frequencies and mode shapes. In automotive structures, the trustworthiness arrangement of the structure extremely depends on joints. In this paper, top hat structure is modelled and designed with spot welding joint using dissimilar materials which is mild steel 1010 and stainless steel 304, using finite element software. Different types of connector elements such as rigid body element (RBE2), welding joint element (CWELD), and bar element (CBAR) are applied to represent real connection between two dissimilar plates. Normal mode analysis is simulated with different types of joining element in order to determine modal properties. Natural frequencies using RBE2, CBAR and CWELD are compared to equivalent rigid body method. Connection that gives the lowest percentage error among these three will be selected as the most reliable joining for resistance spot weld. From the analysis, it is shown that CWELD is better compared to others in term of weld joining among dissimilar plate materials. It is expected that joint modelling of finite element plays significant role in structural dynamics.

Physiologically relevant organs on chips.

PubMed

Yum, Kyungsuk; Hong, Soon Gweon; Healy, Kevin E; Lee, Luke P

2014-01-01

Recent advances in integrating microengineering and tissue engineering have generated promising microengineered physiological models for experimental medicine and pharmaceutical research. Here we review the recent development of microengineered physiological systems, or also known as "ogans-on-chips", that reconstitute the physiologically critical features of specific human tissues and organs and their interactions. This technology uses microengineering approaches to construct organ-specific microenvironments, reconstituting tissue structures, tissue-tissue interactions and interfaces, and dynamic mechanical and biochemical stimuli found in specific organs, to direct cells to assemble into functional tissues. We first discuss microengineering approaches to reproduce the key elements of physiologically important, dynamic mechanical microenvironments, biochemical microenvironments, and microarchitectures of specific tissues and organs in microfluidic cell culture systems. This is followed by examples of microengineered individual organ models that incorporate the key elements of physiological microenvironments into single microfluidic cell culture systems to reproduce organ-level functions. Finally, microengineered multiple organ systems that simulate multiple organ interactions to better represent human physiology, including human responses to drugs, is covered in this review. This emerging organs-on-chips technology has the potential to become an alternative to 2D and 3D cell culture and animal models for experimental medicine, human disease modeling, drug development, and toxicology. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Quality Function Deployment Framework for the Service Quality of Health Information Websites

PubMed Central

Kim, Dohoon

2010-01-01

Objectives This research was conducted to identify both the users' service requirements on health information websites (HIWs) and the key functional elements for running HIWs. With the quality function deployment framework, the derived service attributes (SAs) are mapped into the suppliers' functional characteristics (FCs) to derive the most critical FCs for the users' satisfaction. Methods Using the survey data from 228 respondents, the SAs, FCs and their relationships were analyzed using various multivariate statistical methods such as principal component factor analysis, discriminant analysis, correlation analysis, etc. Simple and compound FC priorities were derived by matrix calculation. Results Nine factors of SAs and five key features of FCs were identified, and these served as the basis for the house of quality model. Based on the compound FC priorities, the functional elements pertaining to security and privacy, and usage support should receive top priority in the course of enhancing HIWs. Conclusions The quality function deployment framework can improve the FCs of the HIWs in an effective, structured manner, and it can also be utilized for critical success factors together with their strategic implications for enhancing the service quality of HIWs. Therefore, website managers could efficiently improve website operations by considering this study's results. PMID:21818418

Analytical Chemistry: A retrospective view on some current trends.

PubMed

Niessner, Reinhard

2018-04-01

In a retrospective view some current trends in Analytical Chemistry are outlined and connected to work published more than a hundred years ago in the same field. For example, gravimetric microanalysis after specific precipitation, once the sole basis for chemical analysis, has been transformed into a mass-sensitive transducer in combination with compound-specific receptors. Molecular spectroscopy, still practising the classical absorption/emission techniques for detecting elements or molecules experiences a change to Raman spectroscopy, is now allowing analysis of a multitude of additional features. Chemical sensors are now used to perform a vast number of analytical measurements. Especially paper-based devices (dipsticks, microfluidic pads) celebrate a revival as they can potentially revolutionize medicine in the developing world. Industry 4.0 will lead to a further increase of sensor applications. Preceding separation and enrichment of analytes from complicated matrices remains the backbone for a successful analysis, despite increasing attempts to avoid clean-up. Continuous separation techniques will become a key element for 24/7 production of goods with certified quality. Attempts to get instantaneous and specific chemical information by optical or electrical transduction will need highly selective receptors in large quantities. Further understanding of ligand - receptor complex structures is the key for successful generation of artificial bio-inspired receptors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fatigue impact on Mod-1 wind turbine design

NASA Technical Reports Server (NTRS)

Stahle, C. V., Jr.

1978-01-01

Fatigue is a key consideration in the design of a long-life Wind Turbine Generator (WTG) system. This paper discusses the fatigue aspects of the large Mod-1 horizontal-axis WTG design starting with the characterization of the environment and proceeding through the design. Major sources of fatigue loading are discussed and methods of limiting fatigue loading are described. NASTRAN finite element models are used to determine dynamic loading and internal cyclic stresses. Recent developments in determining the allowable fatigue stress consistent with present construction codes are discussed relative to their application to WTG structural design.

Terahertz amplification in RTD-gated HEMTs with a grating-gate wave coupling topology

NASA Astrophysics Data System (ADS)

Condori Quispe, Hugo O.; Encomendero-Risco, Jimy J.; Xing, Huili Grace; Sensale-Rodriguez, Berardi

2016-08-01

We theoretically analyze the operation of a terahertz amplifier consisting of a resonant-tunneling-diode gated high-electron-mobility transistor (RTD-gated HEMT) in a grating-gate topology. In these devices, the key element enabling substantial power gain is the efficient coupling of terahertz waves into and out of plasmons in the RTD-gated HEMT channel, i.e., the gain medium, via the grating-gate itself, part of the active device, rather than by an external antenna structure as discussed in previous works, therefore potentially enabling terahertz amplification with associated power gains >40 dB.

The Million-Body Problem: Particle Simulations in Astrophysics

ScienceCinema

Rasio, Fred

2018-05-21

Computer simulations using particles play a key role in astrophysics. They are widely used to study problems across the entire range of astrophysical scales, from the dynamics of stars, gaseous nebulae, and galaxies, to the formation of the largest-scale structures in the universe. The 'particles' can be anything from elementary particles to macroscopic fluid elements, entire stars, or even entire galaxies. Using particle simulations as a common thread, this talk will present an overview of computational astrophysics research currently done in our theory group at Northwestern. Topics will include stellar collisions and the gravothermal catastrophe in dense star clusters.

The Geographic Concentration of Enterprise in Developing Countries

PubMed Central

Felkner, John S.; Townsend, Robert M.

2011-01-01

A nation’s economic geography can have an enormous impact on its development. In Thailand, we show that a high concentration of enterprise in an area predicts high subsequent growth in and around that area. We also find spatially contiguous convergence of enterprise with stagnant areas left behind. Exogenous physiographic conditions are correlated with enterprise location and growth. We fit a structural, micro-founded model of occupation transitions with fine-tuned geographic capabilities to village data and replicate these salient facts. Key elements of the model include costs, credit constraints on occupation choice, and spatially varying expansion of financial service providers. PMID:22844158

Religion, kinship and health behaviors of African American women.

PubMed

Coe, Kathryn; Keller, Colleen; Walker, Jenelle R

2015-02-01

A positive relationship exists between functional health and religion. We present an empirical definition of religion and describe the key elements of religious behavior, building a model that can be used to explore the presumed relationship between religion and health. Semi-structured interactive interviews were conducted with 22 participants over a 6-month period. Head Start programs and churches located in the inner city of a large metropolitan area. Twenty-two African American women were aged from 21 to 45. We focus on social relationships and propose that prophet-created religions mimic kinship relationships and encourage kinship-like cooperation between members.

Terahertz amplification in RTD-gated HEMTs with a grating-gate wave coupling topology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Condori Quispe, Hugo O.; Sensale-Rodriguez, Berardi; Encomendero-Risco, Jimy J.

2016-08-08

We theoretically analyze the operation of a terahertz amplifier consisting of a resonant-tunneling-diode gated high-electron-mobility transistor (RTD-gated HEMT) in a grating-gate topology. In these devices, the key element enabling substantial power gain is the efficient coupling of terahertz waves into and out of plasmons in the RTD-gated HEMT channel, i.e., the gain medium, via the grating-gate itself, part of the active device, rather than by an external antenna structure as discussed in previous works, therefore potentially enabling terahertz amplification with associated power gains >40 dB.

SEACAS Theory Manuals: Part II. Nonlinear Continuum Mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attaway, S.W.; Laursen, T.A.; Zadoks, R.I.

1998-09-01

This report summarizes the key continuum mechanics concepts required for the systematic prescription and numerical solution of finite deformation solid mechanics problems. Topics surveyed include measures of deformation appropriate for media undergoing large deformations, stress measures appropriate for such problems, balance laws and their role in nonlinear continuum mechanics, the role of frame indifference in description of large deformation response, and the extension of these theories to encompass two dimensional idealizations, structural idealizations, and rigid body behavior. There are three companion reports that describe the problem formulation, constitutive modeling, and finite element technology for nonlinear continuum mechanics systems.

Integrating multiparametric prostate MRI into clinical practice

PubMed Central

2011-01-01

Abstract Multifunctional magnetic resonance imaging (MRI) techniques are increasingly being used to address bottlenecks in prostate cancer patient management. These techniques yield qualitative, semi-quantitative and fully quantitative biomarkers that reflect on the underlying biological status of a tumour. If these techniques are to have a role in patient management, then standard methods of data acquisition, analysis and reporting have to be developed. Effective communication by the use of scoring systems, structured reporting and a graphical interface that matches prostate anatomy are key elements. Practical guidelines for integrating multiparametric MRI into clinical practice are presented. PMID:22187067

KSC-06pd2292

NASA Image and Video Library

2006-10-13

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is mated to its twin solid rocket boosters on the mobile launch platform in high bay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6 feet wide and 154 feet tall. STS-116 will be mission No. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

KSC-06pd2291

NASA Image and Video Library

2006-10-13

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is mated to its twin solid rocket boosters on the mobile launch platform in high bay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6 feet wide and 154 feet tall. STS-116 will be mission No. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

KSC-06pd2289

NASA Image and Video Library

2006-10-13

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is mated to its twin solid rocket boosters on the mobile launch platform in high bay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6-feet wide and 154-feet tall. STS-116 will be mission No. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

KSC-06pd2290

NASA Image and Video Library

2006-10-13

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is mated to its twin solid rocket boosters on the mobile launch platform in high bay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the space shuttle system at 27.6 feet wide and 154 feet tall. STS-116 will be mission No. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

KSC-06pd2293

NASA Image and Video Library

2006-10-13

KENNEDY SPACE CENTER, FLA. - Inside the Vehicle Assembly Building, the external tank is mated to its twin solid rocket boosters on the mobile launch platform in high bay 3 for mission STS-116. The gigantic, rust-colored external tank is the largest element of the Space Shuttle system at 27.6 feet wide and 154 feet tall. STS-116 will be mission No. 20 to the International Space Station and construction flight 12A.1. The mission payload is the SPACEHAB module, the P5 integrated truss structure and other key components. Launch is scheduled for no earlier than Dec. 7. Photo credit: NASA/Jack Pfaller

One-dimensional swarm algorithm packaging

NASA Astrophysics Data System (ADS)

Lebedev, Boris K.; Lebedev, Oleg B.; Lebedeva, Ekaterina O.

2018-05-01

The paper considers an algorithm for solving the problem of onedimensional packaging based on the adaptive behavior model of an ant colony. The key role in the development of the ant algorithm is the choice of representation (interpretation) of the solution. The structure of the solution search graph, the procedure for finding solutions on the graph, the methods of deposition and evaporation of pheromone are described. Unlike the canonical paradigm of an ant algorithm, an ant on the solution search graph generates sets of elements distributed across blocks. Experimental studies were conducted on IBM PC. Compared with the existing algorithms, the results are improved.

Structural studies of Saccharomyces cerevesiae mitochondrial NADP-dependent isocitrate dehydrogenase in different enzymatic states reveal substantial conformational changes during the catalytic reaction.

PubMed

Peng, Yingjie; Zhong, Chen; Huang, Wei; Ding, Jianping

2008-09-01

Isocitrate dehydrogenases (IDHs) catalyze oxidative decarboxylation of isocitrate (ICT) into alpha-ketoglutarate (AKG). We report here the crystal structures of Saccharomyces cerevesiae mitochondrial NADP-IDH Idp1p in binary complexes with coenzyme NADP, or substrate ICT, or product AKG, and in a quaternary complex with NADPH, AKG, and Ca(2+), which represent different enzymatic states during the catalytic reaction. Analyses of these structures identify key residues involved in the binding of these ligands. Comparisons among these structures and with the previously reported structures of other NADP-IDHs reveal that eukaryotic NADP-IDHs undergo substantial conformational changes during the catalytic reaction. Binding or release of the ligands can cause significant conformational changes of the structural elements composing the active site, leading to rotation of the large domain relative to the small and clasp domains along two hinge regions (residues 118-124 and residues 284-287) while maintaining the integrity of its secondary structural elements, and thus, formation of at least three distinct overall conformations. Specifically, the enzyme adopts an open conformation when bound to NADP, a quasi-closed conformation when bound to ICT or AKG, and a fully closed conformation when bound to NADP, ICT, and Ca(2+) in the pseudo-Michaelis complex or with NADPH, AKG, and Ca(2+) in the product state. The conformational changes of eukaryotic NADP-IDHs are quite different from those of Escherichia coli NADP-IDH, for which significant conformational changes are observed only between two forms of the apo enzyme, suggesting that the catalytic mechanism of eukaryotic NADP-IDHs is more complex than that of EcIDH, and involves more fine-tuned conformational changes.

Structural studies of Saccharomyces cerevesiae mitochondrial NADP-dependent isocitrate dehydrogenase in different enzymatic states reveal substantial conformational changes during the catalytic reaction

PubMed Central

Peng, Yingjie; Zhong, Chen; Huang, Wei; Ding, Jianping

2008-01-01

Isocitrate dehydrogenases (IDHs) catalyze oxidative decarboxylation of isocitrate (ICT) into α-ketoglutarate (AKG). We report here the crystal structures of Saccharomyces cerevesiae mitochondrial NADP-IDH Idp1p in binary complexes with coenzyme NADP, or substrate ICT, or product AKG, and in a quaternary complex with NADPH, AKG, and Ca2+, which represent different enzymatic states during the catalytic reaction. Analyses of these structures identify key residues involved in the binding of these ligands. Comparisons among these structures and with the previously reported structures of other NADP-IDHs reveal that eukaryotic NADP-IDHs undergo substantial conformational changes during the catalytic reaction. Binding or release of the ligands can cause significant conformational changes of the structural elements composing the active site, leading to rotation of the large domain relative to the small and clasp domains along two hinge regions (residues 118–124 and residues 284–287) while maintaining the integrity of its secondary structural elements, and thus, formation of at least three distinct overall conformations. Specifically, the enzyme adopts an open conformation when bound to NADP, a quasi-closed conformation when bound to ICT or AKG, and a fully closed conformation when bound to NADP, ICT, and Ca2+ in the pseudo-Michaelis complex or with NADPH, AKG, and Ca2+ in the product state. The conformational changes of eukaryotic NADP-IDHs are quite different from those of Escherichia coli NADP-IDH, for which significant conformational changes are observed only between two forms of the apo enzyme, suggesting that the catalytic mechanism of eukaryotic NADP-IDHs is more complex than that of EcIDH, and involves more fine-tuned conformational changes. PMID:18552125

Virus World as an Evolutionary Network of Viruses and Capsidless Selfish Elements

PubMed Central

Dolja, Valerian V.

2014-01-01

SUMMARY Viruses were defined as one of the two principal types of organisms in the biosphere, namely, as capsid-encoding organisms in contrast to ribosome-encoding organisms, i.e., all cellular life forms. Structurally similar, apparently homologous capsids are present in a huge variety of icosahedral viruses that infect bacteria, archaea, and eukaryotes. These findings prompted the concept of the capsid as the virus “self” that defines the identity of deep, ancient viral lineages. However, several other widespread viral “hallmark genes” encode key components of the viral replication apparatus (such as polymerases and helicases) and combine with different capsid proteins, given the inherently modular character of viral evolution. Furthermore, diverse, widespread, capsidless selfish genetic elements, such as plasmids and various types of transposons, share hallmark genes with viruses. Viruses appear to have evolved from capsidless selfish elements, and vice versa, on multiple occasions during evolution. At the earliest, precellular stage of life's evolution, capsidless genetic parasites most likely emerged first and subsequently gave rise to different classes of viruses. In this review, we develop the concept of a greater virus world which forms an evolutionary network that is held together by shared conserved genes and includes both bona fide capsid-encoding viruses and different classes of capsidless replicons. Theoretical studies indicate that selfish replicons (genetic parasites) inevitably emerge in any sufficiently complex evolving ensemble of replicators. Therefore, the key signature of the greater virus world is not the presence of a capsid but rather genetic, informational parasitism itself, i.e., various degrees of reliance on the information processing systems of the host. PMID:24847023

Conductivity and local structure in LaNiO3

NASA Astrophysics Data System (ADS)

Fowlie, Jennifer; Gibert, Marta; Tieri, Giulio; Gloter, Alexandre; à+/-Iguez, Jorge; Filippetti, Alessio; Catalano, Sara; Gariglio, Stefano; StéPhan, Odile; Triscone, Jean-Marc

In this study we approach the thickness-dependence of the properties of LaNiO3 films along multiple, complementary avenues: sophisticated ab initio calculations, scanning transmission electron microscopy and electronic transport. Specifically, we find an unexpected maximum in conductivity in films of thickness 6 - 10 unit cells (3 nm) for several series of LaNiO3 films. Ab initio transport based on the detailed crystal structure also reveals a maximum in conductivity at the same thickness. In agreement with the structure obtained from scanning transmission electron microscopy (STEM), our simulated structures reveal that the substrate- and surface-induced distortions lead to three types of local structure (heterointerface, interior-layer, surface). Based on this observation, a 3-element parallel conductor model neatly reproduces the trend of conductivity with thickness. This study addresses the question of how structural distortions at the atomic scale evolve in a thin film under the influence of the substrate and the surface. This topic is key to the understanding of the physics of heterostructures and the design of functional oxides.

Temperature-driven topological quantum phase transitions in a phase-change material Ge2Sb2Te5.

PubMed

Eremeev, S V; Rusinov, I P; Echenique, P M; Chulkov, E V

2016-12-13

The Ge 2 Sb 2 Te 5 is a phase-change material widely used in optical memory devices and is a leading candidate for next generation non-volatile random access memory devices which are key elements of various electronics and portable systems. Despite the compound is under intense investigation its electronic structure is currently not fully understood. The present work sheds new light on the electronic structure of the Ge 2 Sb 2 Te 5 crystalline phases. We demonstrate by predicting from first-principles calculations that stable crystal structures of Ge 2 Sb 2 Te 5 possess different topological quantum phases: a topological insulator phase is realized in low-temperature structure and Weyl semimetal phase is a characteristic of the high-temperature structure. Since the structural phase transitions are caused by the temperature the switching between different topologically non-trivial phases can be driven by variation of the temperature. The obtained results reveal the rich physics of the Ge 2 Sb 2 Te 5 compound and open previously unexplored possibility for spintronics applications of this material, substantially expanding its application potential.

Itinerancy of money

NASA Astrophysics Data System (ADS)

Yasutomi, Ayumu

2003-09-01

Previously, I studied [Physica D 82, 180-194 (1995)] the emergence and collapse of money in a computer simulation model. In this paper I will revisit the same topic, building a model in the same line. I discuss this problem from the viewpoint of chaotic itinerancy. Money is the most popular system for evading the difficulty of exchange under division of labor. It emerges autonomously from exchanges among selfish agents which behave as automata. And such emergent money collapses autonomously. I describe money as a structure in economic space, explaining its autonomous emergence and collapse as two phases of the same phenomenon. The key element in this phenomenon is the switch of the meaning of strategies. This is caused by the drastic change of environment caused by the emergence of a structure. This dynamics shares some aspects with chaotic itinerancy.

Nonlocal Poisson-Fermi double-layer models: Effects of nonuniform ion sizes on double-layer structure

NASA Astrophysics Data System (ADS)

Xie, Dexuan; Jiang, Yi

2018-05-01

This paper reports a nonuniform ionic size nonlocal Poisson-Fermi double-layer model (nuNPF) and a uniform ionic size nonlocal Poisson-Fermi double-layer model (uNPF) for an electrolyte mixture of multiple ionic species, variable voltages on electrodes, and variable induced charges on boundary segments. The finite element solvers of nuNPF and uNPF are developed and applied to typical double-layer tests defined on a rectangular box, a hollow sphere, and a hollow rectangle with a charged post. Numerical results show that nuNPF can significantly improve the quality of the ionic concentrations and electric fields generated from uNPF, implying that the effect of nonuniform ion sizes is a key consideration in modeling the double-layer structure.

Simulation Analysis of Temperature Field in the Heat Transfer Process of Shell

NASA Astrophysics Data System (ADS)

Zhang, Di; Luo, Zhen; Xuan, Wenbo

Sea temperature is the key factors that determines whether shellfish can maintain normal growth development and survival, as protective film, the shell is a very important part of structure of shellfish, so the research of heat transfer characteristics become very important. In this paper, we firstly make a comprehensive analysis on the appearance of the shell, for the next simulation builds a good foundation, and based on the large general finite element analysis software ANSYS, we analyze the thermodynamics of shells, study the effect of the shell thickness and structure on heat transfer time. And through apply different temperature load, analyze the heat transfer characteristics and temperature distribution of the shells, It is expected that the results is useful at the biological heat transfer of shellfish.

UNICON: A Powerful and Easy-to-Use Compound Library Converter.

PubMed

Sommer, Kai; Friedrich, Nils-Ole; Bietz, Stefan; Hilbig, Matthias; Inhester, Therese; Rarey, Matthias

2016-06-27

The accurate handling of different chemical file formats and the consistent conversion between them play important roles for calculations in complex cheminformatics workflows. Working with different cheminformatic tools often makes the conversion between file formats a mandatory step. Such a conversion might become a difficult task in cases where the information content substantially differs. This paper describes UNICON, an easy-to-use software tool for this task. The functionality of UNICON ranges from file conversion between standard formats SDF, MOL2, SMILES, PDB, and PDBx/mmCIF via the generation of 2D structure coordinates and 3D structures to the enumeration of tautomeric forms, protonation states, and conformer ensembles. For this purpose, UNICON bundles the key elements of the previously described NAOMI library in a single, easy-to-use command line tool.

Effective drinking water collaborations are not accidental: interagency relationships in the international water utility sector.

PubMed

Jalba, D I; Cromar, N J; Pollard, S J T; Charrois, J W; Bradshaw, R; Hrudey, S E

2014-02-01

The role that deficient institutional relationships have played in aggravating drinking water incidents over the last 30 years has been identified in several inquiries of high profile drinking water safety events, peer-reviewed articles and media reports. These indicate that collaboration between water utilities and public health agencies (PHAs) during normal operations, and in emergencies, needs improvement. Here, critical elements of these interagency collaborations, that can be integrated within the corporate risk management structures of water utilities and PHAs alike, were identified using a grounded theory approach and 51 semi-structured interviews with utility and PHA staff. Core determinants of effective interagency relationships are discussed. Intentionally maintained functional relationships represent a key ingredient in assuring the delivery of safe, high quality drinking water. © 2013.

Application of Foldcore Sandwich Structures in Helicopter Subfloor Energy Absorption Structure

NASA Astrophysics Data System (ADS)

Zhou, H. Z.; Wang, Z. J.

2017-10-01

The intersection element is an important part of the helicopter subfloor structure. The numerical simulation model of the intersection element is established and the crush simulation is conducted. The simulation results agree well with the experiment results. In order to improve the buffering capacity and energy-absorbing capacity, the intersection element is redesigned. The skin and the floor in the intersection element are replaced with foldcore sandwich structures. The new intersection element is studied using the same simulation method as the typical intersection element. The analysis result shows that foldcore can improve the buffering capacity and the energy-absorbing capacity, and reduce the structure mass.

Molecular structure of human KATP in complex with ATP and ADP

PubMed Central

Lee, Kenneth Pak Kin

2017-01-01

In many excitable cells, KATP channels respond to intracellular adenosine nucleotides: ATP inhibits while ADP activates. We present two structures of the human pancreatic KATP channel, containing the ABC transporter SUR1 and the inward-rectifier K+ channel Kir6.2, in the presence of Mg2+ and nucleotides. These structures, referred to as quatrefoil and propeller forms, were determined by single-particle cryo-EM at 3.9 Å and 5.6 Å, respectively. In both forms, ATP occupies the inhibitory site in Kir6.2. The nucleotide-binding domains of SUR1 are dimerized with Mg2+-ATP in the degenerate site and Mg2+-ADP in the consensus site. A lasso extension forms an interface between SUR1 and Kir6.2 adjacent to the ATP site in the propeller form and is disrupted in the quatrefoil form. These structures support the role of SUR1 as an ADP sensor and highlight the lasso extension as a key regulatory element in ADP’s ability to override ATP inhibition. PMID:29286281

Highly parallel sparse Cholesky factorization

NASA Technical Reports Server (NTRS)

Gilbert, John R.; Schreiber, Robert

1990-01-01

Several fine grained parallel algorithms were developed and compared to compute the Cholesky factorization of a sparse matrix. The experimental implementations are on the Connection Machine, a distributed memory SIMD machine whose programming model conceptually supplies one processor per data element. In contrast to special purpose algorithms in which the matrix structure conforms to the connection structure of the machine, the focus is on matrices with arbitrary sparsity structure. The most promising algorithm is one whose inner loop performs several dense factorizations simultaneously on a 2-D grid of processors. Virtually any massively parallel dense factorization algorithm can be used as the key subroutine. The sparse code attains execution rates comparable to those of the dense subroutine. Although at present architectural limitations prevent the dense factorization from realizing its potential efficiency, it is concluded that a regular data parallel architecture can be used efficiently to solve arbitrarily structured sparse problems. A performance model is also presented and it is used to analyze the algorithms.

Aeroservoelastic and Structural Dynamics Research on Smart Structures Conducted at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

McGowan, Anna-Maria Rivas; Wilkie, W. Keats; Moses, Robert W.; Lake, Renee C.; Florance, Jennifer Pinkerton; Wieseman, Carol D.; Reaves, Mercedes C.; Taleghani, Barmac K.; Mirick, Paul H.; Wilbur, Mathew L.

1997-01-01

An overview of smart structures research currently underway at the NASA Langley Research Center in the areas of aeroservoelasticity and structural dynamics is presented. Analytical and experimental results, plans, potential technology pay-offs, and challenges are discussed. The goal of this research is to develop the enabling technologies to actively and passively control aircraft and rotorcraft vibration and loads using smart devices. These enabling technologies and related research efforts include developing experimentally-validated finite element and aeroservoelastic modeling techniques; conducting bench experimental tests to assess feasibility and understand system trade-offs; and conducting large-scale wind tunnel tests to demonstrate system performance. The key aeroservoelastic applications of this research include: active twist control of rotor blades using interdigitated electrode piezoelectric composites and active control of flutter, and gust and buffeting responses using discrete piezoelectric patches. In addition, NASA Langley is an active participant in the DARPA/Air Force Research Laboratory/NASA/Northrop Grumman Smart Wing program which is assessing aerodynamic performance benefits using smart materials.

Creating of structure of facts for the knowledge base of an expert system for wind power plant's equipment diagnosis

NASA Astrophysics Data System (ADS)

Duer, Stanisław; Wrzesień, Paweł; Duer, Radosław

2017-10-01

This article describes rules and conditions for making a structure (a set) of facts for an expert knowledge base of the intelligent system to diagnose Wind Power Plants' equipment. Considering particular operational conditions of a technical object, that is a set of Wind Power Plant's equipment, this is a significant issue. A structural model of Wind Power Plant's equipment is developed. Based on that, a functional - diagnostic model of Wind Power Plant's equipment is elaborated. That model is a basis for determining primary elements of the object structure, as well as for interpreting a set of diagnostic signals and their reference signals. The key content of this paper is a description of rules for building of facts on the basis of developed analytical dependence. According to facts, their dependence is described by rules for transferring of a set of pieces of diagnostic information into a specific set of facts. The article consists of four chapters that concern particular issues on the subject.

Structural Sizing Methodology for the Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) System

NASA Technical Reports Server (NTRS)

Jones, Thomas C.; Dorsey, John T.; Doggett, William R.

2015-01-01

The Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) is a versatile long-reach robotic manipulator that is currently being tested at NASA Langley Research Center. TALISMAN is designed to be highly mass-efficient and multi-mission capable, with applications including asteroid retrieval and manipulation, in-space servicing, and astronaut and payload positioning. The manipulator uses a modular, periodic, tension-compression design that lends itself well to analytical modeling. Given the versatility of application for TALISMAN, a structural sizing methodology was developed that could rapidly assess mass and configuration sensitivities for any specified operating work space, applied loads and mission requirements. This methodology allows the systematic sizing of the key structural members of TALISMAN, which include the truss arm links, the spreaders and the tension elements. This paper summarizes the detailed analytical derivations and methodology that support the structural sizing approach and provides results from some recent TALISMAN designs developed for current and proposed mission architectures.

‘Umpolung’ Reactivity in Semiaqueous Amide and Peptide Synthesis

PubMed Central

Shen, Bo; Makley, Dawn M.; Johnston, Jeffrey N.

2010-01-01

The amide functional group is one of Nature’s key functional and structural elements, most notably within peptides. Amides are also key intermediates in the preparation of a diverse range of therapeutic small molecules. Its construction using available methods focuses principally upon dehydrative approaches, although oxidative and radical-based methods are representative alternatives. During the carbon-nitrogen bond forming step in most every example, the carbon and nitrogen bear electrophilic and nucleophilic character, respectively. Here we show that activation of amines and nitroalkanes with an electrophilic iodine source in wet THF can lead directly to amide products. Preliminary observations support a mechanistic construct in which reactant polarity is reversed (umpolung) during C-N bond formation relative to traditional approaches. The use of nitroalkanes as acyl anion equivalents provides a conceptually innovative approach to amide and peptide synthesis, and one that might ultimately provide for efficient peptide synthesis that is fully reliant on enantioselective methods. PMID:20577205

Miniaturized supercapacitors: key materials and structures towards autonomous and sustainable devices and systems.

PubMed

Soavi, Francesca; Bettini, Luca Giacomo; Piseri, Paolo; Milani, Paolo; Santoro, Carlo; Atanassov, Plamen; Arbizzani, Catia

2016-09-15

Supercapacitors (SCs) are playing a key role for the development of self-powered and self-sustaining integrated systems for different fields ranging from remote sensing, robotics and medical devices. SC miniaturization and integration into more complex systems that include energy harvesters and functional devices are valuable strategies that address system autonomy. Here, we discuss about novel SC fabrication and integration approaches. Specifically, we report about the results of interdisciplinary activities on the development of thin, flexible SCs by an additive technology based on Supersonic Cluster Beam Deposition (SCBD) to be implemented into supercapacitive electrolyte gated transistors and supercapacitive microbial fuel cells. Such systems integrate at materials level the specific functions of devices, like electric switch or energy harvesting with the reversible energy storage capability. These studies might open new frontiers for the development and application of new multifunction-energy storage elements.

Hospital organisation, management, and structure for prevention of health-care-associated infection: a systematic review and expert consensus.

PubMed

Zingg, Walter; Holmes, Alison; Dettenkofer, Markus; Goetting, Tim; Secci, Federica; Clack, Lauren; Allegranzi, Benedetta; Magiorakos, Anna-Pelagia; Pittet, Didier

2015-02-01

Despite control efforts, the burden of health-care-associated infections in Europe is high and leads to around 37,000 deaths each year. We did a systematic review to identify crucial elements for the organisation of effective infection-prevention programmes in hospitals and key components for implementation of monitoring. 92 studies published from 1996 to 2012 were assessed and ten key components identified: organisation of infection control at the hospital level; bed occupancy, staffing, workload, and employment of pool or agency nurses; availability of and ease of access to materials and equipment and optimum ergonomics; appropriate use of guidelines; education and training; auditing; surveillance and feedback; multimodal and multidisciplinary prevention programmes that include behavioural change; engagement of champions; and positive organisational culture. These components comprise manageable and widely applicable ways to reduce health-care-associated infections and improve patients' safety. Copyright © 2015 Elsevier Ltd. All rights reserved.

Memoized Symbolic Execution

NASA Technical Reports Server (NTRS)

Yang, Guowei; Pasareanu, Corina S.; Khurshid, Sarfraz

2012-01-01

This paper introduces memoized symbolic execution (Memoise), a novel approach for more efficient application of forward symbolic execution, which is a well-studied technique for systematic exploration of program behaviors based on bounded execution paths. Our key insight is that application of symbolic execution often requires several successive runs of the technique on largely similar underlying problems, e.g., running it once to check a program to find a bug, fixing the bug, and running it again to check the modified program. Memoise introduces a trie-based data structure that stores the key elements of a run of symbolic execution. Maintenance of the trie during successive runs allows re-use of previously computed results of symbolic execution without the need for re-computing them as is traditionally done. Experiments using our prototype embodiment of Memoise show the benefits it holds in various standard scenarios of using symbolic execution, e.g., with iterative deepening of exploration depth, to perform regression analysis, or to enhance coverage.

Miniaturized supercapacitors: key materials and structures towards autonomous and sustainable devices and systems

NASA Astrophysics Data System (ADS)

Soavi, Francesca; Bettini, Luca Giacomo; Piseri, Paolo; Milani, Paolo; Santoro, Carlo; Atanassov, Plamen; Arbizzani, Catia

2016-09-01

Supercapacitors (SCs) are playing a key role for the development of self-powered and self-sustaining integrated systems for different fields ranging from remote sensing, robotics and medical devices. SC miniaturization and integration into more complex systems that include energy harvesters and functional devices are valuable strategies that address system autonomy. Here, we discuss about novel SC fabrication and integration approaches. Specifically, we report about the results of interdisciplinary activities on the development of thin, flexible SCs by an additive technology based on Supersonic Cluster Beam Deposition (SCBD) to be implemented into supercapacitive electrolyte gated transistors and supercapacitive microbial fuel cells. Such systems integrate at materials level the specific functions of devices, like electric switch or energy harvesting with the reversible energy storage capability. These studies might open new frontiers for the development and application of new multifunction-energy storage elements.

Self-Alining, Latching Joint For Folding Structural Elements

NASA Technical Reports Server (NTRS)

Bush, H. G.; Wallsom, R. E.

1982-01-01

Structural column elements assembled quickly and easily with aid of new center joint. Joint alines column elements automatically and fastens them together securely. Tapered half columns are stacked like paper cups, unfolded, and connected to other similar elements to form truss structures.

Advances and trends in structures and dynamics; Proceedings of the Symposium, Washington, DC, October 22-25, 1984

NASA Technical Reports Server (NTRS)

Noor, A. K. (Editor); Hayduk, R. J. (Editor)

1985-01-01

Among the topics discussed are developments in structural engineering hardware and software, computation for fracture mechanics, trends in numerical analysis and parallel algorithms, mechanics of materials, advances in finite element methods, composite materials and structures, determinations of random motion and dynamic response, optimization theory, automotive tire modeling methods and contact problems, the damping and control of aircraft structures, and advanced structural applications. Specific topics covered include structural design expert systems, the evaluation of finite element system architectures, systolic arrays for finite element analyses, nonlinear finite element computations, hierarchical boundary elements, adaptive substructuring techniques in elastoplastic finite element analyses, automatic tracking of crack propagation, a theory of rate-dependent plasticity, the torsional stability of nonlinear eccentric structures, a computation method for fluid-structure interaction, the seismic analysis of three-dimensional soil-structure interaction, a stress analysis for a composite sandwich panel, toughness criterion identification for unidirectional composite laminates, the modeling of submerged cable dynamics, and damping synthesis for flexible spacecraft structures.

Geologic Cross Section D-D' Through the Appalachian Basin from the Findlay Arch, Sandusky County, Ohio, to the Valley and Ridge Province, Hardy County, West Virginia

USGS Publications Warehouse

Ryder, Robert T.; Crangle, Robert D.; Trippi, Michael H.; Swezey, Christopher S.; Lentz, Erika E.; Rowan, Elisabeth L.; Hope, Rebecca S.

2009-01-01

Geologic cross section D-D' is the second in a series of cross sections constructed by the U.S. Geological Survey to document and improve understanding of the geologic framework and petroleum systems of the Appalachian basin. Cross section D-D' provides a regional view of the structural and stratigraphic framework of the Appalachian basin from the Findlay arch in northwestern Ohio to the Valley and Ridge province in eastern West Virginia, a distance of approximately 290 miles. The information shown on the cross section is based on geological and geophysical data from 13 deep drill holes, several of which penetrate the Paleozoic sedimentary rocks of the basin and bottom in Mesoproterozoic (Grenville-age) crystalline basement rocks. This cross section is a companion to cross section E-E' (Ryder and others, 2008) that is located about 25 to 50 mi to the southwest. Although specific petroleum systems in the Appalachian basin are not identified on the cross section, many of their key elements (such as source rocks, reservoir rocks, seals, and traps) can be inferred from lithologic units, unconformities, and geologic structures shown on the cross section. Other aspects of petroleum systems (such as the timing of petroleum generation and preferred migration pathways) may be evaluated by burial history, thermal history, and fluid flow models based on information shown on the cross section. Cross section D-D' lacks the detail to illustrate key elements of coal systems (such as paleoclimate, coal quality, and coal rank), but it does provide a general geologic framework (stratigraphic units and general rock types) for the coal-bearing section. Also, cross section D-D' may be used as a reconnaissance tool to identify plausible geologic structures and strata for the subsurface storage of liquid waste or for the sequestration of carbon dioxide.

From spatially variable streamflow to distributed hydrological models: Analysis of key modeling decisions

NASA Astrophysics Data System (ADS)

Fenicia, Fabrizio; Kavetski, Dmitri; Savenije, Hubert H. G.; Pfister, Laurent

2016-02-01

This paper explores the development and application of distributed hydrological models, focusing on the key decisions of how to discretize the landscape, which model structures to use in each landscape element, and how to link model parameters across multiple landscape elements. The case study considers the Attert catchment in Luxembourg—a 300 km2 mesoscale catchment with 10 nested subcatchments that exhibit clearly different streamflow dynamics. The research questions are investigated using conceptual models applied at hydrologic response unit (HRU) scales (1-4 HRUs) on 6 hourly time steps. Multiple model structures are hypothesized and implemented using the SUPERFLEX framework. Following calibration, space/time model transferability is tested using a split-sample approach, with evaluation criteria including streamflow prediction error metrics and hydrological signatures. Our results suggest that: (1) models using geology-based HRUs are more robust and capture the spatial variability of streamflow time series and signatures better than models using topography-based HRUs; this finding supports the hypothesis that, in the Attert, geology exerts a stronger control than topography on streamflow generation, (2) streamflow dynamics of different HRUs can be represented using distinct and remarkably simple model structures, which can be interpreted in terms of the perceived dominant hydrologic processes in each geology type, and (3) the same maximum root zone storage can be used across the three dominant geological units with no loss in model transferability; this finding suggests that the partitioning of water between streamflow and evaporation in the study area is largely independent of geology and can be used to improve model parsimony. The modeling methodology introduced in this study is general and can be used to advance our broader understanding and prediction of hydrological behavior, including the landscape characteristics that control hydrologic response, the dominant processes associated with different landscape types, and the spatial relations of catchment processes. This article was corrected on 14 MAR 2016. See the end of the full text for details.