Vibration health monitoring for tensegrity structures

NASA Astrophysics Data System (ADS)

Ashwear, Nasseradeen; Eriksson, Anders

2017-02-01

Tensegrities are assembly structures, getting their equilibrium from the interaction between tension in cables and compression in bars. During their service life, slacking in their cables and nearness to buckling in their bars need to be monitored to avoid a sudden collapse. This paper discusses how to design the tensegrities to make them feasible for vibrational health monitoring methods. Four topics are discussed; suitable finite elements formulation, pre-measurements analysis to find the locations of excitation and sensors for the interesting modes, the effects from some environmental conditions, and the pre-understanding of the effects from different slacking scenarios.

Smart Metamaterial Based on the Simplex Tensegrity Pattern.

PubMed

Al Sabouni-Zawadzka, Anna; Gilewski, Wojciech

2018-04-26

In the present paper, a novel cellular metamaterial that was based on a tensegrity pattern is presented. The material is constructed from supercells, each of which consists of eight 4-strut simplex modules. The proposed metamaterial exhibits some unusual properties, which are typical for smart structures. It is possible to control its mechanical characteristics by adjusting the level of self-stress or by changing the properties of structural members. A continuum model is used to identify the qualitative properties of the considered metamaterial, and to estimate how the applied self-stress and the characteristics of cables and struts affect the whole structure. The performed analyses proved that the proposed structure can be regarded as a smart metamaterial with orthotropic properties. One of its most important features are unique values of Poisson’s ratio, which can be either positive or negative, depending on the applied control parameters. Moreover, all of the mechanical characteristics of the proposed metamaterial are prone to structural control.

Tensegrity and mechanoregulation: from skeleton to cytoskeleton

NASA Technical Reports Server (NTRS)

Chen, C. S.; Ingber, D. E.

1999-01-01

OBJECTIVE: To elucidate how mechanical stresses that are applied to the whole organism are transmitted to individual cells and transduced into a biochemical response. DESIGN: In this article, we describe fundamental design principles that are used to stabilize the musculoskeletal system at many different size scales and show that these design features are embodied in one particular form of architecture that is known as tensegrity. RESULTS: Tensegrity structures are characterized by use of continuous tension and local compression; architecture, prestress (internal stress prior to application of external force), and triangulation play the most critical roles in terms of determining their mechanical stability. In living organisms, use of a hierarchy of tensegrity networks both optimizes structural efficiency and provides a mechanism to mechanically couple the parts with the whole: mechanical stresses applied at the macroscale result in structural rearrangements at the cell and molecular level. CONCLUSION: Due to use of tensegrity architecture, mechanical stress is concentrated and focused on signal transducing molecules that physically associate with cell surface molecules that anchor cells to extracellular matrix, such as integrins, and with load-bearing elements within the internal cytoskeleton and nucleus. Mechanochemical transduction may then proceed through local stress-dependent changes in molecular mechanics, thermodynamics, and kinetics within the cell. In this manner, the entire cellular response to stress may be orchestrated and tuned by altering the prestress in the cell, just as changing muscular tone can alter mechanical stability and structural coordination throughout the whole musculoskeletal system.

The analysis of tensegrity structures for the design of a morphing wing

NASA Astrophysics Data System (ADS)

Moored, Keith W., III; Bart-Smith, Hilary

2005-05-01

Tensegrity structures have become of engineering interest in recent years, but very few have found practical use. This lack of integration is attributed to the lack of a well formulated design procedure. In this paper, a preliminary procedure is presented for developing morphing tensegrity structures that include actuating elements. To do this, the virtual work method has been modified to allow for individual actuation of struts and cables. A generalized connectivity matrix for a cantilever beam constructed from either a single 4-strut cell or multiple 4-strut cells has been developed. Global deflections resulting from actuation of specific elements have been calculated. Furthermore, the force density method is expanded to include a necessary upper bound condition such that a physically feasible structure can be designed. Finally, the importance of relative force density values on the overall shape of a structure comprising of multiple unit cells is discussed.

Biologically-Inspired Control for a Planetary Exploration Tensegrity Robot

NASA Technical Reports Server (NTRS)

Leroy, Marc

2017-01-01

Tensegrity structures are becoming increasingly popular as mechanical structures for robots. Their inherent compliance makes them extremely robust to environmental disturbances, and their design allows them to have a high strength-to-weight ratio whilst being lightweight compared to traditional robots. For these reasons they would be of interest to the aerospace industry, particularly for planetary exploration. However, being such compliant structures thanks to their network of elastic elements also means that their control is not an easy task. Relying solely on traditional control strategies to generate efficient locomotion would surely be near impossible due to the complex oscillatory motions and nonlinear interactions of its members. The goal of this project was to use bio-inspired control techniques to generate locomotion for a tensegrity icosahedron, namely the SUPERball project of the Intelligent Robotics Group of NASA Ames Research Center.

Comparison of massage based on the tensegrity principle and classic massage in treating chronic shoulder pain.

PubMed

Kassolik, Krzysztof; Andrzejewski, Waldemar; Brzozowski, Marcin; Wilk, Iwona; Górecka-Midura, Lucyna; Ostrowska, Bożena; Krzyżanowski, Dominik; Kurpas, Donata

2013-09-01

The purpose of this study was to compare the clinical outcomes of classic massage to massage based on the tensegrity principle for patients with chronic idiopathic shoulder pain. Thirty subjects with chronic shoulder pain symptoms were divided into 2 groups, 15 subjects received classic (Swedish) massage to tissues surrounding the glenohumeral joint and 15 subjects received the massage using techniques based on the tensegrity principle. The tensegrity principle is based on directing treatment to the painful area and the tissues (muscles, fascia, and ligaments) that structurally support the painful area, thus treating tissues that have direct and indirect influence on the motion segment. Both treatment groups received 10 sessions over 2 weeks, each session lasted 20 minutes. The McGill Pain Questionnaire and glenohumeral ranges of motion were measured immediately before the first massage session, on the day the therapy ended 2 weeks after therapy started, and 1 month after the last massage. Subjects receiving massage based on the tensegrity principle demonstrated statistically significance improvement in the passive and active ranges of flexion and abduction of the glenohumeral joint. Pain decreased in both massage groups. This study showed increases in passive and active ranges of motion for flexion and abduction in patients who had massage based on the tensegrity principle. For pain outcomes, both classic and tensegrity massage groups demonstrated improvement. Copyright © 2013 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

On the geometrically nonlinear elastic response of class θ = 1 tensegrity prisms

NASA Astrophysics Data System (ADS)

Mascolo, Ida; Amendola, Ada; Zuccaro, Giulio; Feo, Luciano; Fraternali, Fernando

2018-03-01

The present work studies the geometrically nonlinear response of class ϑ=1 tensegrity prisms modeled as a collection of elastic springs reacting in tension (strings or cables) or compression (bars), under uniform uniaxial loading. The incremental equilibrium equations of the structure are numerically solved through a path-following procedure, with the aim of modeling the mechanical behavior of the structure in the large displacement regime. Several numerical results are presented with reference to a variety of physical models, which use two different materials for the cables and the bars, and show different aspect ratios associated with either 'standard' or 'expanded' configurations. An experimental validation of the predicted constitutive response is conducted with reference to a 'thick' and a 'slender' model, observing rather good theory vs. experiment matching. The given numerical and experimental results highlight that the elastic response of the examined structures may switch from stiffening to softening, depending on the geometry of the system, the magnitude of the external load, and the applied prestress. The outcomes of the current study confirm previous literature results on the elastic response of minimal tensegrity prisms, and pave the way to the use of tensegrity systems as nonlinear spring units forming tunable mechanical metamaterials.

Parallel kinematic mechanisms for distributed actuation of future structures

NASA Astrophysics Data System (ADS)

Lai, G.; Plummer, A. R.; Cleaver, D. J.; Zhou, H.

2016-09-01

Future machines will require distributed actuation integrated with load-bearing structures, so that they are lighter, move faster, use less energy, and are more adaptable. Good examples are shape-changing aircraft wings which can adapt precisely to the ideal aerodynamic form for current flying conditions, and light but powerful robotic manipulators which can interact safely with human co-workers. A 'tensegrity structure' is a good candidate for this application due to its potentially excellent stiffness and strength-to-weight ratio and a multi-element structure into which actuators could be embedded. This paper presents results of an analysis of an example practical actuated tensegrity structure consisting of 3 ‘unit cells’. A numerical method is used to determine the stability of the structure with varying actuator length, showing how four actuators can be used to control movement in three degrees of freedom as well as simultaneously maintaining the structural pre-load. An experimental prototype has been built, in which 4 pneumatic artificial muscles (PAMs) are embedded in one unit cell. The PAMs are controlled antagonistically, by high speed switching of on-off valves, to achieve control of position and structure pre-load. Experimental and simulation results are presented, and future prospects for the approach are discussed.

On tensegrity in cell mechanics.

PubMed

Volokh, K Y

2011-09-01

All models are wrong, but some are useful. This famous saying mirrors the situation in cell mechanics as well. It looks like no particular model of the cell deformability can be unconditionally preferred over others and different models reveal different aspects of the mechanical behavior of living cells. The purpose of the present work is to discuss the so-called tensegrity models of the cell cytoskeleton. It seems that the role of the cytoskeleton in the overall mechanical response of the cell was not appreciated until Donald Ingber put a strong emphasis on it. It was fortunate that Ingber linked the cytoskeletal structure to the fascinating art of tensegrity architecture. This link sparked interest and argument among biologists, physicists, mathematicians, and engineers. At some point the enthusiasm regarding tensegrity perhaps became overwhelming and as a reaction to that some skepticism built up. To demystify Ingber's ideas the present work aims at pinpointing the meaning of tensegrity and its role in our understanding of the importance of the cytoskeleton for the cell deformability and motility. It should be noted also that this paper emphasizes basic ideas rather than carefully follows the chronology of the development of tensegrity models. The latter can be found in the comprehensive review by Dimitrije Stamenovic (2006) to which the present work is complementary.

Optimization of a tensegrity wing for biomimetic applications

NASA Astrophysics Data System (ADS)

Moored, Keith W., III; Taylor, Stuart A.; Bart-Smith, Hilary

2006-03-01

Current attempts to build fast, efficient, and maneuverable underwater vehicles have looked to nature for inspiration. However, they have all been based on traditional propulsive techniques, i.e. rotary motors. In the current study a promising and potentially revolutionary approach is taken that overcomes the limitations of these traditional methods-morphing structure concepts with integrated actuation and sensing. Inspiration for this work comes from the manta ray (Manta birostris) and other batoid fish. These creatures are highly maneuverable but are also able to cruise at high speeds over long distances. In this paper, the structural foundation for the biomimetic morphing wing is a tensegrity structure. A preliminary procedure is presented for developing morphing tensegrity structures that include actuating elements. A shape optimization method is used that determines actuator placement and actuation amount necessary to achieve the measured biological displacement field of a ray. Lastly, an experimental manta ray wing is presented that measures the static and dynamic pressure field acting on the ray's wings during a normal flapping cycle.

A microstructural approach to cytoskeletal mechanics based on tensegrity

NASA Technical Reports Server (NTRS)

Stamenovic, D.; Fredberg, J. J.; Wang, N.; Butler, J. P.; Ingber, D. E.

1996-01-01

Mechanical properties of living cells are commonly described in terms of the laws of continuum mechanics. The purpose of this report is to consider the implications of an alternative approach that emphasizes the discrete nature of stress bearing elements in the cell and is based on the known structural properties of the cytoskeleton. We have noted previously that tensegrity architecture seems to capture essential qualitative features of cytoskeletal shape distortion in adherent cells (Ingber, 1993a; Wang et al., 1993). Here we extend those qualitative notions into a formal microstructural analysis. On the basis of that analysis we attempt to identify unifying principles that might underlie the shape stability of the cytoskeleton. For simplicity, we focus on a tensegrity structure containing six rigid struts interconnected by 24 linearly elastic cables. Cables carry initial tension ("prestress") counterbalanced by compression of struts. Two cases of interconnectedness between cables and struts are considered: one where they are connected by pin-joints, and the other where the cables run through frictionless loops at the junctions. At the molecular level, the pinned structure may represent the case in which different cytoskeletal filaments are cross-linked whereas the looped structure represents the case where they are free to slip past one another. The system is then subjected to uniaxial stretching. Using the principal of virtual work, stretching force vs. extension and structural stiffness vs. stretching force relationships are calculated for different prestresses. The stiffness is found to increase with increasing prestress and, at a given prestress, to increase approximately linearly with increasing stretching force. This behavior is consistent with observations in living endothelial cells exposed to shear stresses (Wang & Ingber, 1994). At a given prestress, the pinned structure is found to be stiffer than the looped one, a result consistent with data on mechanical behavior of isolated, cross-linked and uncross-linked actin networks (Wachsstock et al., 1993). On the basis of our analysis we concluded that architecture and the prestress of the cytoskeleton might be key features that underlie a cell's ability to regulate its shape.

The effectiveness of massage based on the tensegrity principle compared with classical abdominal massage performed on patients with constipation.

PubMed

Kassolik, Krzysztof; Andrzejewski, Waldemar; Wilk, Iwona; Brzozowski, Marcin; Voyce, Kamila; Jaworska-Krawiecka, Ewa; Nowak, Barbara; Kurpas, Donata

2015-01-01

The purpose of the study was to compare the effectiveness of massage based on the tensegrity principle and classical abdominal massage performed on patients with constipation. The study group consisted of 29 subjects with a pre-existing diagnosis of constipation based on the Rome III criteria. The patients were divided into two groups: the first group was made up of 15 patients who underwent tensegrity massage (average age: 59.8 years), and the second was made up of 14 patients who were given classical abdominal massage (average age: 55.7 years). The study consisted of six massage sessions in both groups, with two sessions per week performed over 21 days. The assessment was based on a patient questionnaire, the Rome III questionnaire and a diary of bowel movements. The results were analyzed before therapy, after one week of therapy and after the third (final) week of therapy. Changes in the number of defecations were compared between the two groups; the biggest changes occurred in the first and third week of therapy (P<0.01, calculated by the Mann-Whitey test). As a result of the therapy, tension during defecation dropped from 60% to 20% in Group I, and from 42.8% to 35.7% in Group II. The influence of the applied therapy was evaluated positively by 80% of the tensegrity massage group and 29% of the classical abdominal massage group. Massage based on the tensegrity principle may have a greater positive influence on the quality and quantity of bowel movements than classical abdominal massage. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Design and Evolution of a Modular Tensegrity Robot Platform

NASA Technical Reports Server (NTRS)

Bruce, Jonathan; Caluwaerts, Ken; Iscen, Atil; Sabelhaus, Andrew P.; SunSpiral, Vytas

2014-01-01

NASA Ames Research Center is developing a compliant modular tensegrity robotic platform for planetary exploration. In this paper we present the design and evolution of the platform's main hardware component, an untethered, robust tensegrity strut, with rich sensor feedback and cable actuation. Each strut is a complete robot, and multiple struts can be combined together to form a wide range of complex tensegrity robots. Our current goal for the tensegrity robotic platform is the development of SUPERball, a 6-strut icosahedron underactuated tensegrity robot aimed at dynamic locomotion for planetary exploration rovers and landers, but the aim is for the modular strut to enable a wide range of tensegrity morphologies. SUPERball is a second generation prototype, evolving from the tensegrity robot ReCTeR, which is also a modular, lightweight, highly compliant 6-strut tensegrity robot that was used to validate our physics based NASA Tensegrity Robot Toolkit (NTRT) simulator. Many hardware design parameters of the SUPERball were driven by locomotion results obtained in our validated simulator. These evolutionary explorations helped constrain motor torque and speed parameters, along with strut and string stress. As construction of the hardware has finalized, we have also used the same evolutionary framework to evolve controllers that respect the built hardware parameters.

Tensegrity: the architectural basis of cellular mechanotransduction

NASA Technical Reports Server (NTRS)

Ingber, D. E.

1997-01-01

Physical forces of gravity, hemodynamic stresses, and movement play a critical role in tissue development. Yet, little is known about how cells convert these mechanical signals into a chemical response. This review attempts to place the potential molecular mediators of mechanotransduction (e.g. stretch-sensitive ion channels, signaling molecules, cytoskeleton, integrins) within the context of the structural complexity of living cells. The model presented relies on recent experimental findings, which suggests that cells use tensegrity architecture for their organization. Tensegrity predicts that cells are hard-wired to respond immediately to mechanical stresses transmitted over cell surface receptors that physically couple the cytoskeleton to extracellular matrix (e.g. integrins) or to other cells (cadherins, selectins, CAMs). Many signal transducing molecules that are activated by cell binding to growth factors and extracellular matrix associate with cytoskeletal scaffolds within focal adhesion complexes. Mechanical signals, therefore, may be integrated with other environmental signals and transduced into a biochemical response through force-dependent changes in scaffold geometry or molecular mechanics. Tensegrity also provides a mechanism to focus mechanical energy on molecular transducers and to orchestrate and tune the cellular response.

Biomechanics and Biotensegrity: Study Method and Frequency Response of the Simplex and 3-bar-SVD Tensegrity Configurations

NASA Astrophysics Data System (ADS)

Castro Arenas, C.; Ghersi, I.; Miralles, M. T.

2016-04-01

The purpose of this work is to study the frequency response of 3D tensegrity structures. These are structures that have been used, since the 80’s, to model biological systems of different scales. This fact led to the origin of the field of biotensegrity, which includes biomechanics as a natural field of application. In this work: a) A simple method for the analysis of frequency response of different nodes in 3D tensegrity structures was set up and tuned. This method is based on a video-analysis algorithm, which was applied to the structures, as they were vibrated along their axis of symmetry, at frequencies from 1 Hz to 60 Hz. b) Frequency-response analyses were performed, for the simplest 3D structure, the Simplex module, as well as for two towers, formed by stacking two and three Simplex modules, respectively. Resonant frequencies were detected for the Simplex module at (19.2±0.1) Hz and (50.2±0.1) Hz (the latter being an average of frequencies between homologous nodes). For the towers with two and three modules, each selected node presented a characteristic frequency response, modulated by their spatial placement in each model. Resonances for the two-stage tower were found at: (12±0.1) Hz; (16.2±0.1) Hz; (29.4±0.1) Hz and (37.2±0.1) Hz. For the tower with three Simplex modules, the main resonant frequencies were found at (12.0±0.1) Hz and (21.0±0.1) Hz. Results show that the proposed method is adequate for the study (2D) of any 3D tensegrity structure, with the potential of being generalized to the study of oscillations in three dimensions. A growing complexity and variability in the frequency response of the nodes was observed, as modules were added to the structures. These findings were compared to those found in the available literature.

Tensegrity II. How structural networks influence cellular information processing networks

NASA Technical Reports Server (NTRS)

Ingber, Donald E.

2003-01-01

The major challenge in biology today is biocomplexity: the need to explain how cell and tissue behaviors emerge from collective interactions within complex molecular networks. Part I of this two-part article, described a mechanical model of cell structure based on tensegrity architecture that explains how the mechanical behavior of the cell emerges from physical interactions among the different molecular filament systems that form the cytoskeleton. Recent work shows that the cytoskeleton also orients much of the cell's metabolic and signal transduction machinery and that mechanical distortion of cells and the cytoskeleton through cell surface integrin receptors can profoundly affect cell behavior. In particular, gradual variations in this single physical control parameter (cell shape distortion) can switch cells between distinct gene programs (e.g. growth, differentiation and apoptosis), and this process can be viewed as a biological phase transition. Part II of this article covers how combined use of tensegrity and solid-state mechanochemistry by cells may mediate mechanotransduction and facilitate integration of chemical and physical signals that are responsible for control of cell behavior. In addition, it examines how cell structural networks affect gene and protein signaling networks to produce characteristic phenotypes and cell fate transitions during tissue development.

State Estimation for Tensegrity Robots

NASA Technical Reports Server (NTRS)

Caluwaerts, Ken; Bruce, Jonathan; Friesen, Jeffrey M.; Sunspiral, Vytas

2016-01-01

Tensegrity robots are a class of compliant robots that have many desirable traits when designing mass efficient systems that must interact with uncertain environments. Various promising control approaches have been proposed for tensegrity systems in simulation. Unfortunately, state estimation methods for tensegrity robots have not yet been thoroughly studied. In this paper, we present the design and evaluation of a state estimator for tensegrity robots. This state estimator will enable existing and future control algorithms to transfer from simulation to hardware. Our approach is based on the unscented Kalman filter (UKF) and combines inertial measurements, ultra wideband time-of-flight ranging measurements, and actuator state information. We evaluate the effectiveness of our method on the SUPERball, a tensegrity based planetary exploration robotic prototype. In particular, we conduct tests for evaluating both the robot's success in estimating global position in relation to fixed ranging base stations during rolling maneuvers as well as local behavior due to small-amplitude deformations induced by cable actuation.

Scientific Toy

NASA Technical Reports Server (NTRS)

1989-01-01

Tensegritoy, inspired by the tensegrity concepts of R. Buckminster Fuller, is an erector set like toy designed to give students an understanding of structural stability. It is used by children, architects, engineers, and teachers. The manufacturer, Tensegrity Systems Corporation, also offers a collapsible point of purchase display which incorporates technology developed for space station trusses described in "NASA Tech Briefs." The tech brief described deployable trusses that can be collapsed into small packages for space shuttle transport, then unfolded in space. As a result, the display occupies a minimum amount of floor space, freight cost savings are substantial and assembly can be completed quickly.

The origin of cellular life.

PubMed

Ingber, D E

2000-12-01

This essay presents a scenario of the origin of life that is based on analysis of biological architecture and mechanical design at the microstructural level. My thesis is that the same architectural and energetic constraints that shape cells today also guided the evolution of the first cells and that the molecular scaffolds that support solid-phase biochemistry in modern cells represent living microfossils of past life forms. This concept emerged from the discovery that cells mechanically stabilize themselves using tensegrity architecture and that these same building rules guide hierarchical self-assembly at all size scales (Sci. Amer 278:48-57;1998). When combined with other fundamental design principles (e.g., energy minimization, topological constraints, structural hierarchies, autocatalytic sets, solid-state biochemistry), tensegrity provides a physical basis to explain how atomic and molecular elements progressively self-assembled to create hierarchical structures with increasingly complex functions, including living cells that can self-reproduce.

The origin of cellular life

NASA Technical Reports Server (NTRS)

Ingber, D. E.

2000-01-01

This essay presents a scenario of the origin of life that is based on analysis of biological architecture and mechanical design at the microstructural level. My thesis is that the same architectural and energetic constraints that shape cells today also guided the evolution of the first cells and that the molecular scaffolds that support solid-phase biochemistry in modern cells represent living microfossils of past life forms. This concept emerged from the discovery that cells mechanically stabilize themselves using tensegrity architecture and that these same building rules guide hierarchical self-assembly at all size scales (Sci. Amer 278:48-57;1998). When combined with other fundamental design principles (e.g., energy minimization, topological constraints, structural hierarchies, autocatalytic sets, solid-state biochemistry), tensegrity provides a physical basis to explain how atomic and molecular elements progressively self-assembled to create hierarchical structures with increasingly complex functions, including living cells that can self-reproduce.

Tensegrity, cellular biophysics, and the mechanics of living systems

PubMed Central

Ingber, Donald E.; Wang, Ning; Stamenović, Dimitrije

2014-01-01

The recent convergence between physics and biology has led many physicists to enter the fields of cell and developmental biology. One of the most exciting areas of interest has been the emerging field of mechanobiology that centers on how cells control their mechanical properties, and how physical forces regulate cellular biochemical responses, a process that is known as mechanotransduction. In this article, we review the central role that tensegrity (tensional integrity) architecture, which depends on tensile prestress for its mechanical stability, plays in biology. We describe how tensional prestress is a critical governor of cell mechanics and function, and how use of tensegrity by cells contributes to mechanotransduction. Theoretical tensegrity models are also described that predict both quantitative and qualitative behaviors of living cells, and these theoretical descriptions are placed in context of other physical models of the cell. In addition, we describe how tensegrity is used at multiple size scales in the hierarchy of life — from individual molecules to whole living organisms — to both stabilize three-dimensional form and to channel forces from the macroscale to the nanoscale, thereby facilitating mechanochemical conversion at the molecular level. PMID:24695087

The Application of Tensegrity Massage in a Professionally Active Musician - Case Report.

PubMed

Wilk, Iwona; Kurpas, Donata; Andrzejewski, Waldemar; Okręglicka-Forysiak, Ewa; Gworys, Bohdan; Kassolik, Krzysztof

2016-01-01

The purpose of our study was to present options for the application of tensegrity massage to manage pain caused by the overload of soft tissues in musicians. Tensegrity massage was applied to a 34-year-old male violinist. The methodology included a correct positioning and tensegrity massage with individually designed procedure. After therapy, the patient achieved complete pain relief, and relaxation of muscles in the shoulder girdle and free part of the upper arm. The analgesic effect lasted for 6 months after the end of therapy. Massage is an effective method in eliminating pain caused by the overload of soft tissues. If used regularly before physical effort, it can prevent muscle overload. The presented massage procedure is an effective therapy in pain caused by the overload of soft tissues in musicians and it can be one of the elements of complex physiotherapy in active musicians. © 2014 Association of Rehabilitation Nurses.

Application of Tensegrity Massage to Relive Complications After Mastectomy--Case Report.

PubMed

Wilk, Iwona; Kurpas, Donata; Mroczek, Bozena; Andrzejewski, Waldemar; Okręglicka-Forysiak, Ewa; Krawiecka-Jaworska, Ewa; Kassolik, Krzysztof

2015-01-01

The case study was to determine the effectiveness of tensegrity massage in a patient after mastectomy. Tensegrity massage was performed in a 50-year-old woman after mastectomy. The purpose of the massage was to normalize the tension of musculo-ligamento-fascial system in the chest, shoulder girdle, and back. The patient was subjected to a series of six massage sessions, 45 minutes each, twice a week. The applied massage therapy contributed to the reduction of the postoperative scar tenderness and painfulness, to the relaxation of the muscular tone within the shoulder girdle, and to the improvement of the patient's general feeling. Tensegrity massage is an effective therapy in the elimination of pain and abnormal tissue tension induced by extensive scarring after mastectomy. The presented massage procedure had a positive effect immediately after the therapy and after 1-month follow-up. © 2014 Association of Rehabilitation Nurses.

Alternative Suspension System for Space Shuttle Avionics Shelf

NASA Technical Reports Server (NTRS)

Biele, Frank H., III

2010-01-01

Engineers working in the Aerospace field under deadlines and strict budgets often miss the opportunity to design something that is considered new or innovative, favoring instead to use the tried-and-true design over those that may, in fact, be more efficient. This thesis examines an electronic equipment stowage shelf suspended from a frame in the cargo bay (mid fuselage) of the United States Space Transportation System (STS), the Space Shuttle, and 3 alternative designs. Four different designs are examined and evaluated. The first design is a conventional truss, representing the tried and true approach. The second is a cable dome type structure consisting of struts and pre-stressed wiring. The third and fourth are double layer tensegrity systems consisting of contiguous struts of the order k=1 and k=2 respectively.

Mechanical forces as information: an integrated approach to plant and animal development

PubMed Central

Hernández-Hernández, Valeria; Rueda, Denisse; Caballero, Lorena; Alvarez-Buylla, Elena R.; Benítez, Mariana

2014-01-01

Mechanical forces such as tension and compression act throughout growth and development of multicellular organisms. These forces not only affect the size and shape of the cells and tissues but are capable of modifying the expression of genes and the localization of molecular components within the cell, in the plasma membrane, and in the plant cell wall. The magnitude and direction of these physical forces change with cellular and tissue properties such as elasticity. Thus, mechanical forces and the mesoscopic fields that emerge from their local action constitute important sources of positional information. Moreover, physical and biochemical processes interact in non-linear ways during tissue and organ growth in plants and animals. In this review we discuss how such mechanical forces are generated, transmitted, and sensed in these two lineages of multicellular organisms to yield long-range positional information. In order to do so we first outline a potentially common basis for studying patterning and mechanosensing that relies on the structural principle of tensegrity, and discuss how tensegral structures might arise in plants and animals. We then provide some examples of morphogenesis in which mechanical forces appear to act as positional information during development, offering a possible explanation for ubiquitous processes, such as the formation of periodic structures. Such examples, we argue, can be interpreted in terms of tensegral phenomena. Finally, we discuss the hypothesis of mechanically isotropic points as a potentially generic mechanism for the localization and maintenance of stem-cell niches in multicellular organisms. This comparative approach aims to help uncovering generic mechanisms of morphogenesis and thus reach a better understanding of the evolution and development of multicellular phenotypes, focusing on the role of physical forces in these processes. PMID:24959170

Mechanical forces as information: an integrated approach to plant and animal development.

PubMed

Hernández-Hernández, Valeria; Rueda, Denisse; Caballero, Lorena; Alvarez-Buylla, Elena R; Benítez, Mariana

2014-01-01

Mechanical forces such as tension and compression act throughout growth and development of multicellular organisms. These forces not only affect the size and shape of the cells and tissues but are capable of modifying the expression of genes and the localization of molecular components within the cell, in the plasma membrane, and in the plant cell wall. The magnitude and direction of these physical forces change with cellular and tissue properties such as elasticity. Thus, mechanical forces and the mesoscopic fields that emerge from their local action constitute important sources of positional information. Moreover, physical and biochemical processes interact in non-linear ways during tissue and organ growth in plants and animals. In this review we discuss how such mechanical forces are generated, transmitted, and sensed in these two lineages of multicellular organisms to yield long-range positional information. In order to do so we first outline a potentially common basis for studying patterning and mechanosensing that relies on the structural principle of tensegrity, and discuss how tensegral structures might arise in plants and animals. We then provide some examples of morphogenesis in which mechanical forces appear to act as positional information during development, offering a possible explanation for ubiquitous processes, such as the formation of periodic structures. Such examples, we argue, can be interpreted in terms of tensegral phenomena. Finally, we discuss the hypothesis of mechanically isotropic points as a potentially generic mechanism for the localization and maintenance of stem-cell niches in multicellular organisms. This comparative approach aims to help uncovering generic mechanisms of morphogenesis and thus reach a better understanding of the evolution and development of multicellular phenotypes, focusing on the role of physical forces in these processes.

The effect of a single massage based on the tensegrity principle on postural stability in young women.

PubMed

Cieślik, Błażej; Podsiadły, Ireneusz; Kuczyński, Michał; Ostrowska, Bożena

2017-11-06

The aim of this study was to investigate the effects of normalized muscle tension via tensegrity-based massage on postural stability in a sample of female young adults. Nineteen females aged 21.8 ± 1.9 years were recruited presenting abnormal tension at muscles adhering to any of the following structural sites: superior iliac spine, lateral sacropelvic surface, linea aspera at 1/2 of femur length, and superior nuchal line of the occiput. Balance and postural control were assessed during bipedal stance using a force platform in multiple conditions: hard surface or soft foam surface with the head in either a neutral posture or tilted backward. Baseline and 3-min and 15-min post-treatment measures were collected while barefoot and eyes closed. Main outcomes measures included center of pressure variability, range, radius, and velocity in the anteroposterior (AP) mediolateral (ML) dimensions. In the solid surface with neutral head posture condition only AP COP measures decreased significantly (p< 0.05). In the soft surface condition, significant differences were observed in the AP and ML dimensions among most measures (p< 0.05). A single application of tensegrity-based massage positively influenced postural control in young adult females, particularly in the AP direction.

2016 Summer Series - Vytas SunSpiral - SUPERBall: A Biologically Inspired Robot for Planetary Exploration

NASA Image and Video Library

2016-06-14

Nature is a major source of inspiration for robotics and aerospace engineering, giving rise to biologically inspired structures. Tensegrity robots mimic a structure similar to muscles and bones to produce a robust three-dimensional skeletal structure that is able to adapt. Vytas SunSpiral will present his work on biologically inspired robotics for advancing NASA space exploration missions.

Mandibular anterior crowding: normal or pathological?

PubMed

Consolaro, Alberto; Cardoso, Mauricio de Almeida

2018-01-01

The teeth become very close to each other when they are crowded, but their structures remain individualized and, in this situation, the role of the epithelial rests of Malassez is fundamental to release the EGF. The concept of tensegrity is fundamental to understand the responses of tissues submitted to forces in body movements, including teeth and their stability in this process. The factors of tooth position stability in the arch - or dental tensegrity - should be considered when one plans and perform an orthodontic treatment. The direct causes of the mandibular anterior crowding are decisive to decide about the correct retainer indication: Should they be applied and indicated throughout life? Should they really be permanently used for lifetime? These aspects of the mandibular anterior crowding and their implication at the orthodontic practice will be discussed here to induct reflections and insights for new researches, as well as advances in knowledge and technology on this subject.

Adaptive and Resilient Soft Tensegrity Robots.

PubMed

Rieffel, John; Mouret, Jean-Baptiste

2018-04-17

Living organisms intertwine soft (e.g., muscle) and hard (e.g., bones) materials, giving them an intrinsic flexibility and resiliency often lacking in conventional rigid robots. The emerging field of soft robotics seeks to harness these same properties to create resilient machines. The nature of soft materials, however, presents considerable challenges to aspects of design, construction, and control-and up until now, the vast majority of gaits for soft robots have been hand-designed through empirical trial-and-error. This article describes an easy-to-assemble tensegrity-based soft robot capable of highly dynamic locomotive gaits and demonstrating structural and behavioral resilience in the face of physical damage. Enabling this is the use of a machine learning algorithm able to discover effective gaits with a minimal number of physical trials. These results lend further credence to soft-robotic approaches that seek to harness the interaction of complex material dynamics to generate a wealth of dynamical behaviors.

Fibre cables in the lacunae of Typha leaves contribute to a tensegrity structure.

PubMed

Witztum, Allan; Wayne, Randy

2014-04-01

Cables composed of long, non-lignified fibre cells enclosed in a cover of much shorter thin-walled, crystal-containing cells traverse the air chambers (lacunae) in leaves of the taller species of Typha. The non-lignified fibre cables are anchored in diaphragms composed of stellate cells of aerenchyma tissue that segment the long air chambers into smaller compartments. Although the fibre cables are easily observed and can be pulled free from the porous-to-air diaphragms, their structure and function have been ignored or misinterpreted. Leaves of various species of Typha were dissected and fibre cables were pulled free and observed with a microscope using bright-field and polarizing optics. Maximal tensile strength of freshly removed cables was measured by hanging weights from fibre cables, and Instron analysis was used to produce curves of load versus extension until cables broke. Polarized light microscopy revealed that the cellulose microfibrils that make up the walls of the cable fibres are oriented parallel to the long axis of the fibres. This orientation ensures that the fibre cables are mechanically stiff and strong under tension. Accordingly, the measured stiffness and tensile strength of the fibre cables were in the gigapascal range. In combination with the dorsal and ventral leaf surfaces and partitions that contain lignified fibre bundles and vascular strands that are strong in compression, the very fine fibre cables that are strong under tension form a tensegrity structure. The tensegrity structure creates multiple load paths through which stresses are redistributed throughout the 1-3 m tall upright leaves of Typha angustifolia, T. latifolia, T. × glauca, T. domingensis and T. shuttleworthii. The length of the fibre cables relative to the length of the leaf blades is reduced in the last-formed leaves of flowering individuals. Fibre cables are absent in the shorter leaves of Typha minima and, if present, only extend for a few centimetres from the sheath into the leaf blade of Typha laxmannii. The advantage of the structure of the Typha leaf blade, which enables stiffness to give way to flexibility under windy conditions, is discussed for both vegetative and flowering plants.

Fibre cables in the lacunae of Typha leaves contribute to a tensegrity structure

PubMed Central

Witztum, Allan; Wayne, Randy

2014-01-01

Background and Aims Cables composed of long, non-lignified fibre cells enclosed in a cover of much shorter thin-walled, crystal-containing cells traverse the air chambers (lacunae) in leaves of the taller species of Typha. The non-lignified fibre cables are anchored in diaphragms composed of stellate cells of aerenchyma tissue that segment the long air chambers into smaller compartments. Although the fibre cables are easily observed and can be pulled free from the porous-to-air diaphragms, their structure and function have been ignored or misinterpreted. Methods Leaves of various species of Typha were dissected and fibre cables were pulled free and observed with a microscope using bright-field and polarizing optics. Maximal tensile strength of freshly removed cables was measured by hanging weights from fibre cables, and Instron analysis was used to produce curves of load versus extension until cables broke. Key Results and Conclusions Polarized light microscopy revealed that the cellulose microfibrils that make up the walls of the cable fibres are oriented parallel to the long axis of the fibres. This orientation ensures that the fibre cables are mechanically stiff and strong under tension. Accordingly, the measured stiffness and tensile strength of the fibre cables were in the gigapascal range. In combination with the dorsal and ventral leaf surfaces and partitions that contain lignified fibre bundles and vascular strands that are strong in compression, the very fine fibre cables that are strong under tension form a tensegrity structure. The tensegrity structure creates multiple load paths through which stresses are redistributed throughout the 1–3 m tall upright leaves of Typha angustifolia, T. latifolia, T. × glauca, T. domingensis and T. shuttleworthii. The length of the fibre cables relative to the length of the leaf blades is reduced in the last-formed leaves of flowering individuals. Fibre cables are absent in the shorter leaves of Typha minima and, if present, only extend for a few centimetres from the sheath into the leaf blade of Typha laxmannii. The advantage of the structure of the Typha leaf blade, which enables stiffness to give way to flexibility under windy conditions, is discussed for both vegetative and flowering plants. PMID:24532647

System Design and Locomotion of Superball, an Untethered Tensegrity Robot

NASA Technical Reports Server (NTRS)

Sabelhaus, Andrew P.; Bruce, Jonathan; Caluwaerts, Ken; Manovi, Pavlo; Firoozi, Roya Fallah; Dobi, Sarah; Agogino, Alice M.; Sunspiral, Vytas

2015-01-01

The Spherical Underactuated Planetary Exploration Robot ball (SUPERball) is an ongoing project within NASA Ames Research Center's Intelligent Robotics Group and the Dynamic Tensegrity Robotics Lab (DTRL). The current SUPERball is the first full prototype of this tensegrity robot platform, eventually destined for space exploration missions. This work, building on prior published discussions of individual components, presents the fully-constructed robot. Various design improvements are discussed, as well as testing results of the sensors and actuators that illustrate system performance. Basic low-level motor position controls are implemented and validated against sensor data, which show SUPERball to be uniquely suited for highly dynamic state trajectory tracking. Finally, SUPERball is shown in a simple example of locomotion. This implementation of a basic motion primitive shows SUPERball in untethered control.

Systematic Image Based Optical Alignment and Tensegrity

NASA Technical Reports Server (NTRS)

Zeiders, Glenn W.; Montgomery, Edward E, IV (Technical Monitor)

2001-01-01

This presentation will review the objectives and current status of two Small Business Innovative Research being performed by the Sirius Group, under the direction of MSFC. They all relate to the development of advanced optical systems technologies for automated segmented mirror alignment techniques and fundamental design methodologies for ultralight structures. These are important to future astronomical missions in space.

Integrins, tensegrity, and mechanotransduction.

PubMed

Ingber, D E

1997-06-01

Physical forces, such as those due to gravity, play an important role in tissue development and remodeling. Yet, little is known about how individual cells sense mechanical signals or how they transduce them into a chemical response. Rather than listing the numerous signal pathways that have been found to be sensitive to mechanical stimulation, we need to place potential molecular signaling mechanisms within the context of the entire cell. The model presented is based on the concept that cells use tensegrity architecture to organize their cytoskeleton and stabilize their form. Studies with stick and string tensegrity cell models predict that living cells are hard-wired to respond immediately to external mechanical stresses. This hard-wiring exists in the form of discrete cytoskeletal filament networks that mechanically couple specific cell surface receptors, such as integrins, to nuclear matrix scaffolds and to potential transducing molecules that physically associate with the cytoskeleton. If these signaling molecules do function in a "solid-state", then mechanical stresses may be transduced into biochemical responses through force-dependent changes in cytoskeletal geometry or through local alterations in thermodynamic or kinetic parameters. Changes in cytoskeletal tension (prestress) also may play a role in signal amplification and adaptation. Recent experimental results are described which provide direct support for the tensegrity theory.

Integrins, tensegrity, and mechanotransduction

NASA Technical Reports Server (NTRS)

Ingber, D. E.

1997-01-01

Physical forces, such as those due to gravity, play an important role in tissue development and remodeling. Yet, little is known about how individual cells sense mechanical signals or how they transduce them into a chemical response. Rather than listing the numerous signal pathways that have been found to be sensitive to mechanical stimulation, we need to place potential molecular signaling mechanisms within the context of the entire cell. The model presented is based on the concept that cells use tensegrity architecture to organize their cytoskeleton and stabilize their form. Studies with stick and string tensegrity cell models predict that living cells are hard-wired to respond immediately to external mechanical stresses. This hard-wiring exists in the form of discrete cytoskeletal filament networks that mechanically couple specific cell surface receptors, such as integrins, to nuclear matrix scaffolds and to potential transducing molecules that physically associate with the cytoskeleton. If these signaling molecules do function in a "solid-state", then mechanical stresses may be transduced into biochemical responses through force-dependent changes in cytoskeletal geometry or through local alterations in thermodynamic or kinetic parameters. Changes in cytoskeletal tension (prestress) also may play a role in signal amplification and adaptation. Recent experimental results are described which provide direct support for the tensegrity theory.

On the mechanical modeling of tensegrity columns subject to impact loading

NASA Astrophysics Data System (ADS)

Amendola, Ada; Favata, Antonino; Micheletti, Andrea

2018-04-01

A physical model of a tensegrity columns is additively manufactured in a titanium alloy. After removing sacrificial supports, such a model is post-tensioned through suitable insertion of Spectra cables. The wave dynamics of the examined system is first experimentally investigated by recording the motion through high-speed cameras assisted by a digital image correlation algorithm, which returns time-histories of the axial displacements of the bases of each prism of the column. Next, the experimental response is mechanically simulated by means of two different models: a stick-and-spring model accounting for the presence of bending-stiff connections between the 3D-printed elements (mixed bending-stretching response), and a tensegrity model accounting for a purely stretching response. The comparison of theory and experiment reveals that the presence of bending-stiff connections weakens the nonlinearity of the wave dynamics of the system. A stretching-dominated response instead supports highly compact solitary waves in the presence of small prestress and negligible bending stiffness of connections.

[Human skull development and voice disorders].

PubMed

Piron, A; Roch, J B

2006-01-01

The hominisation of the skull comes with the bipedic posture, due to a network of muscular and aponevrotic forces applied to the cranio-facial skeleton. A brief sight of the morphogenetic origine and issues of these forces help to understand more clearly the postural statement of the larynx, his functions, and his many extrinsic biomechanical bounds; then further his most frequently dysfunctions. The larynx is surrounded by several effective systems of protection: active, activo-passive, passive. The architectural features of the components of the laryngeal system allows us to consider the laryngeal function as an auto-balanced system. All the forces engaged are auto-balanced in a continuum of tension. This lead us to the concept of tensegrity system, neologism coming from tensional integrity described by Buckminster Fuller. The laryngeal employement by extrinsic system is pathological in case of chronicity. Any osteopathic treatment, which aims to restore the losses of laryngeal mobility, has to release first the peripherical structures involved in the laryngeal defense, before normalising the larynx itself Finally, the larynx recovers his functions in a tensegrity system.

Super Ball Bot - Structures for Planetary Landing and Exploration, NIAC Phase 2 Final Report

NASA Technical Reports Server (NTRS)

SunSpiral, Vytas; Agogino, Adrian; Atkinson, David

2015-01-01

Small, light-weight and low-cost missions will become increasingly important to NASA's exploration goals. Ideally teams of small, collapsible, light weight robots, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such robots will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing lightweight conventional robots is difficult with current technology. Current robot designs are delicate, requiring a complex combination of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead we are developing a radically different robot based on a "tensegrity" structure and built purely with tensile and compression elements. Such robots can be both a landing and a mobility platform allowing for dramatically simpler mission profile and reduced costs. These multi-purpose robots can be light-weight, compactly stored and deployed, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and can provide surface mobility. These properties allow for unique mission profiles that can be carried out with low cost and high reliability and which minimizes the inefficient dependance on "use once and discard" mass associated with traditional landing systems. We believe tensegrity robot technology can play a critical role in future planetary exploration.

Ultralightweight Space Deployable Primary Reflector Demonstrator

NASA Technical Reports Server (NTRS)

Montgomery, Edward E., IV; Zeiders, Glenn W.; Smith, W. Scott (Technical Monitor)

2002-01-01

A concept has been developed and analyzed and several generational prototypes built for a gossamer-class deployable truss for a mirror or reflector with many smaller precisely-figured solid elements attached will, for at least the next several decades, minimize the mass of a large primary mirror assembly while still providing the high image quality essential for planet-finding and cosmological astronomical missions. Primary mirror segments are mounted in turn on ultralightweight thermally-formed plastic panels that hold clusters of mirror segments in rigid arrays whose tip/tilt and piston would be corrected over the scale of the plastic panels by the control segments. Prototype panels developed under this program are 45 cm wide and fabricated from commercially available Kaplan sheets. A three-strut octahedral tensegrity is the basis for the overall support structure. Each fundamental is composed of two such octahedrons, rotated oppositely about a common triangular face. Adjacent modules are joined at the nodes of the upper and lower triangles to form a deployable structure that could be made arbitrarily large. A seven-module dowel-and-wire prototype has been constructed. Deployment techniques based on the use of collapsing toggled struts with diagonal tensional elements allows an assembly of tensegrities to be fully collapsed and redeployed. The prototype designs will be described and results of a test program for measuring strength and deformation will be presented.

Obtaining information by dynamic (effortful) touching

PubMed Central

Turvey, M. T.; Carello, Claudia

2011-01-01

Dynamic touching is effortful touching. It entails deformation of muscles and fascia and activation of the embedded mechanoreceptors, as when an object is supported and moved by the body. It is realized as exploratory activities that can vary widely in spatial and temporal extents (a momentary heft, an extended walk). Research has revealed the potential of dynamic touching for obtaining non-visual information about the body (e.g. limb orientation), attachments to the body (e.g. an object's height and width) and the relation of the body both to attachments (e.g. hand's location on a grasped object) and surrounding surfaces (e.g. places and their distances). Invariants over the exploratory activity (e.g. moments of a wielded object's mass distribution) seem to ground this ‘information about’. The conception of a haptic medium as a nested tensegrity structure has been proposed to express the obtained information realized by myofascia deformation, by its invariants and transformations. The tensegrity proposal rationalizes the relative indifference of dynamic touch to the site of mechanical contact (hand, foot, torso or probe) and the overtness of exploratory activity. It also provides a framework for dynamic touching's fractal nature, and the finding that its degree of fractality may matter to its accomplishments. PMID:21969694

A DNA Crystal Designed to Contain Two Molecules per Asymmetric Unit

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

T Wang; R Sha; J Birktoft

2011-12-31

We describe the self-assembly of a DNA crystal that contains two tensegrity triangle molecules per asymmetric unit. We have used X-ray crystallography to determine its crystal structure. In addition, we have demonstrated control over the colors of the crystals by attaching either Cy3 dye (pink) or Cy5 dye (blue-green) to the components of the crystal, yielding crystals of corresponding colors. Attaching the pair of dyes to the pair of molecules yields a purple crystal.

Mechanisms governing the visco-elastic responses of living cells assessed by foam and tensegrity models.

PubMed

Cañadas, P; Laurent, V M; Chabrand, P; Isabey, D; Wendling-Mansuy, S

2003-11-01

The visco-elastic properties of living cells, measured to date by various authors, vary considerably, depending on the experimental methods and/or on the theoretical models used. In the present study, two mechanisms thought to be involved in cellular visco-elastic responses were analysed, based on the idea that the cytoskeleton plays a fundamental role in cellular mechanical responses. For this purpose, the predictions of an open unit-cell model and a 30-element visco-elastic tensegrity model were tested, taking into consideration similar properties of the constitutive F-actin. The quantitative predictions of the time constant and viscosity modulus obtained by both models were compared with previously published experimental data obtained from living cells. The small viscosity modulus values (10(0)-10(3) Pa x s) predicted by the tensegrity model may reflect the combined contributions of the spatially rearranged constitutive filaments and the internal tension to the overall cytoskeleton response to external loading. In contrast, the high viscosity modulus values (10(3)-10(5) Pa x s) predicted by the unit-cell model may rather reflect the mechanical response of the cytoskeleton to the bending of the constitutive filaments and/or to the deformation of internal components. The present results suggest the existence of a close link between the overall visco-elastic response of micromanipulated cells and the underlying architecture.

Geometric confinement influences cellular mechanical properties I -- adhesion area dependence.

PubMed

Su, Judith; Jiang, Xingyu; Welsch, Roy; Whitesides, George M; So, Peter T C

2007-06-01

Interactions between the cell and the extracellular matrix regulate a variety of cellular properties and functions, including cellular rheology. In the present study of cellular adhesion, area was controlled by confining NIH 3T3 fibroblast cells to circular micropatterned islands of defined size. The shear moduli of cells adhering to islands of well defined geometry, as measured by magnetic microrheometry, was found to have a significantly lower variance than those of cells allowed to spread on unpatterned surfaces. We observe that the area of cellular adhesion influences shear modulus. Rheological measurements further indicate that cellular shear modulus is a biphasic function of cellular adhesion area with stiffness decreasing to a minimum value for intermediate areas of adhesion, and then increasing for cells on larger patterns. We propose a simple hypothesis: that the area of adhesion affects cellular rheological properties by regulating the structure of the actin cytoskeleton. To test this hypothesis, we quantified the volume fraction of polymerized actin in the cytosol by staining with fluorescent phalloidin and imaging using quantitative 3D microscopy. The polymerized actin volume fraction exhibited a similar biphasic dependence on adhesion area. Within the limits of our simplifying hypothesis, our experimental results permit an evaluation of the ability of established, micromechanical models to predict the cellular shear modulus based on polymerized actin volume fraction. We investigated the "tensegrity", "cellular-solids", and "biopolymer physics" models that have, respectively, a linear, quadratic, and 5/2 dependence on polymerized actin volume fraction. All three models predict that a biphasic trend in polymerized actin volume fraction as a function of adhesion area will result in a biphasic behavior in shear modulus. Our data favors a higher-order dependence on polymerized actin volume fraction. Increasingly better experimental agreement is observed for the tensegrity, the cellular solids, and the biopolymer models respectively. Alternatively if we postulate the existence of a critical actin volume fraction below which the shear modulus vanishes, the experimental data can be equivalently described by a model with an almost linear dependence on polymerized actin volume fraction; this observation supports a tensegrity model with a critical actin volume fraction.

Lattice-free prediction of three-dimensional structure of programmed DNA assemblies

PubMed Central

Pan, Keyao; Kim, Do-Nyun; Zhang, Fei; Adendorff, Matthew R.; Yan, Hao; Bathe, Mark

2014-01-01

DNA can be programmed to self-assemble into high molecular weight 3D assemblies with precise nanometer-scale structural features. Although numerous sequence design strategies exist to realize these assemblies in solution, there is currently no computational framework to predict their 3D structures on the basis of programmed underlying multi-way junction topologies constrained by DNA duplexes. Here, we introduce such an approach and apply it to assemblies designed using the canonical immobile four-way junction. The procedure is used to predict the 3D structure of high molecular weight planar and spherical ring-like origami objects, a tile-based sheet-like ribbon, and a 3D crystalline tensegrity motif, in quantitative agreement with experiments. Our framework provides a new approach to predict programmed nucleic acid 3D structure on the basis of prescribed secondary structure motifs, with possible application to the design of such assemblies for use in biomolecular and materials science. PMID:25470497

Preface of "The Second Symposium on Border Zones Between Experimental and Numerical Application Including Solution Approaches By Extensions of Standard Numerical Methods"

NASA Astrophysics Data System (ADS)

Ortleb, Sigrun; Seidel, Christian

2017-07-01

In this second symposium at the limits of experimental and numerical methods, recent research is presented on practically relevant problems. Presentations discuss experimental investigation as well as numerical methods with a strong focus on application. In addition, problems are identified which require a hybrid experimental-numerical approach. Topics include fast explicit diffusion applied to a geothermal energy storage tank, noise in experimental measurements of electrical quantities, thermal fluid structure interaction, tensegrity structures, experimental and numerical methods for Chladni figures, optimized construction of hydroelectric power stations, experimental and numerical limits in the investigation of rain-wind induced vibrations as well as the application of exponential integrators in a domain-based IMEX setting.

A polyhedron made of tRNAs.

PubMed

Severcan, Isil; Geary, Cody; Chworos, Arkadiusz; Voss, Neil; Jacovetty, Erica; Jaeger, Luc

2010-09-01

Supramolecular assembly is a powerful strategy used by nature to build nanoscale architectures with predefined sizes and shapes. With synthetic systems, however, numerous challenges remain to be solved before precise control over the synthesis, folding and assembly of rationally designed three-dimensional nano-objects made of RNA can be achieved. Here, using the transfer RNA molecule as a structural building block, we report the design, efficient synthesis and structural characterization of stable, modular three-dimensional particles adopting the polyhedral geometry of a non-uniform square antiprism. The spatial control within the final architecture allows the precise positioning and encapsulation of proteins. This work demonstrates that a remarkable degree of structural control can be achieved with RNA structural motifs for the construction of thermostable three-dimensional nano-architectures that do not rely on helix bundles or tensegrity. RNA three-dimensional particles could potentially be used as carriers or scaffolds in nanomedicine and synthetic biology.

A polyhedron made of tRNAs

PubMed Central

Severcan, Isil; Geary, Cody; Chworos, Arkadiusz; Voss, Neil; Jacovetty, Erica; Jaeger, Luc

2010-01-01

Supra-molecular assembly is a powerful strategy used by nature for building nano-scale architectures with predefined sizes and shapes. Numerous challenges remain however to be solved in order to demonstrate precise control over the synthesis, folding and assembly of rationally designed three-dimensional (3D) nano-objects made of RNA. Using the transfer RNA molecule as a structural building block, we report the design, efficient synthesis and structural characterization of stable, modular 3D particles adopting the polyhedral geometry of a non-uniform square antiprism. The spatial control within the final architecture allows precise positioning and encapsulation of proteins. This work demonstrates that a remarkable degree of structural control can be achieved with RNA structural motifs to build thermostable 3D nano-architectures that do not rely on helix bundles or tensegrity. RNA 3D particles can potentially be used as carriers or scaffolds in nano-medicine and synthetic biology. PMID:20729899

Tensegrity and motor-driven effective interactions in a model cytoskeleton

NASA Astrophysics Data System (ADS)

Wang, Shenshen; Wolynes, Peter G.

2012-04-01

Actomyosin networks are major structural components of the cell. They provide mechanical integrity and allow dynamic remodeling of eukaryotic cells, self-organizing into the diverse patterns essential for development. We provide a theoretical framework to investigate the intricate interplay between local force generation, network connectivity, and collective action of molecular motors. This framework is capable of accommodating both regular and heterogeneous pattern formation, arrested coarsening and macroscopic contraction in a unified manner. We model the actomyosin system as a motorized cat's cradle consisting of a crosslinked network of nonlinear elastic filaments subjected to spatially anti-correlated motor kicks acting on motorized (fibril) crosslinks. The phase diagram suggests there can be arrested phase separation which provides a natural explanation for the aggregation and coalescence of actomyosin condensates. Simulation studies confirm the theoretical picture that a nonequilibrium many-body system driven by correlated motor kicks can behave as if it were at an effective equilibrium, but with modified interactions that account for the correlation of the motor driven motions of the actively bonded nodes. Regular aster patterns are observed both in Brownian dynamics simulations at effective equilibrium and in the complete stochastic simulations. The results show that large-scale contraction requires correlated kicking.

How cells (might) sense microgravity

NASA Technical Reports Server (NTRS)

Ingber, D.

1999-01-01

This article is a summary of a lecture presented at an ESA/NASA Workshop on Cell and Molecular Biology Research in Space that convened in Leuven, Belgium, in June 1998. Recent studies are reviewed which suggest that cells may sense mechanical stresses, including those due to gravity, through changes in the balance of forces that are transmitted across transmembrane adhesion receptors that link the cytoskeleton to the extracellular matrix and to other cells (e.g., integrins, cadherins, selectins). The mechanism by which these mechanical signals are transduced and converted into a biochemical response appears to be based, in part, on the finding that living cells use a tension-dependent form of architecture, known as tensegrity, to organize and stabilize their cytoskeleton. Because of tensegrity, the cellular response to stress differs depending on the level of pre-stress (pre-existing tension) in the cytoskeleton and it involves all three cytoskeletal filament systems as well as nuclear scaffolds. Recent studies confirm that alterations in the cellular force balance can influence intracellular biochemistry within focal adhesion complexes that form at the site of integrin binding as well as gene expression in the nucleus. These results suggest that gravity sensation may not result from direct activation of any single gravioreceptor molecule. Instead, gravitational forces may be experienced by individual cells in the living organism as a result of stress-dependent changes in cell, tissue, or organ structure that, in turn, alter extracellular matrix mechanics, cell shape, cytoskeletal organization, or internal pre-stress in the cell-tissue matrix.--Ingber, D. How cells (might) sense microgravity.

Self-Assembly of 3D DNA Crystals Containing a Torsionally Stressed Component

DOE PAGES

Hernandez, Carina; Birktoft, Jens J.; Ohayon, Yoel P.; ...

2017-10-05

There is an increasing appreciation for structural diversity of DNA that is of interest to both DNA nanotechnology and basic biology. Here, we have explored how DNA responds to torsional stress by building on a previously reported two-turn DNA tensegrity triangle and demonstrating that we could introduce an extra nucleotide pair (np) into the original sequence without affecting assembly and crystallization. The extra np imposes a significant torsional stress, which is accommodated by global changes throughout the B-DNA duplex and the DNA lattice. Furthermore, the work reveals a near-atomic structure of naked DNA under a torsional stress of approximately 14%,more » and thus provides an example of DNA distortions that occur without a requirement for either an external energy source or the free energy available from protein or drug binding.« less

Morphological communication: exploiting coupled dynamics in a complex mechanical structure to achieve locomotion

PubMed Central

Rieffel, John A.; Valero-Cuevas, Francisco J.; Lipson, Hod

2010-01-01

Traditional engineering approaches strive to avoid, or actively suppress, nonlinear dynamic coupling among components. Biological systems, in contrast, are often rife with these dynamics. Could there be, in some cases, a benefit to high degrees of dynamical coupling? Here we present a distributed robotic control scheme inspired by the biological phenomenon of tensegrity-based mechanotransduction. This emergence of morphology-as-information-conduit or ‘morphological communication’, enabled by time-sensitive spiking neural networks, presents a new paradigm for the decentralized control of large, coupled, modular systems. These results significantly bolster, both in magnitude and in form, the idea of morphological computation in robotic control. Furthermore, they lend further credence to ideas of embodied anatomical computation in biological systems, on scales ranging from cellular structures up to the tendinous networks of the human hand. PMID:19776146

Self-Assembly of 3D DNA Crystals Containing a Torsionally Stressed Component.

PubMed

Hernandez, Carina; Birktoft, Jens J; Ohayon, Yoel P; Chandrasekaran, Arun Richard; Abdallah, Hatem; Sha, Ruojie; Stojanoff, Vivian; Mao, Chengde; Seeman, Nadrian C

2017-11-16

There is an increasing appreciation for structural diversity of DNA that is of interest to both DNA nanotechnology and basic biology. Here, we have explored how DNA responds to torsional stress by building on a previously reported two-turn DNA tensegrity triangle and demonstrating that we could introduce an extra nucleotide pair (np) into the original sequence without affecting assembly and crystallization. The extra np imposes a significant torsional stress, which is accommodated by global changes throughout the B-DNA duplex and the DNA lattice. The work reveals a near-atomic structure of naked DNA under a torsional stress of approximately 14%, and thus provides an example of DNA distortions that occur without a requirement for either an external energy source or the free energy available from protein or drug binding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Self-Assembly of 3D DNA Crystals Containing a Torsionally Stressed Component

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

Hernandez, Carina; Birktoft, Jens J.; Ohayon, Yoel P.

There is an increasing appreciation for structural diversity of DNA that is of interest to both DNA nanotechnology and basic biology. Here, we have explored how DNA responds to torsional stress by building on a previously reported two-turn DNA tensegrity triangle and demonstrating that we could introduce an extra nucleotide pair (np) into the original sequence without affecting assembly and crystallization. The extra np imposes a significant torsional stress, which is accommodated by global changes throughout the B-DNA duplex and the DNA lattice. Furthermore, the work reveals a near-atomic structure of naked DNA under a torsional stress of approximately 14%,more » and thus provides an example of DNA distortions that occur without a requirement for either an external energy source or the free energy available from protein or drug binding.« less

Rapid flow-induced responses in endothelial cells

NASA Technical Reports Server (NTRS)

Stamatas, G. N.; McIntire, L. V.

2001-01-01

Endothelial cells alter their morphology, growth rate, and metabolism in response to fluid shear stress. To study rapid flow-induced responses in the 3D endothelial cell morphology and calcium distribution, coupled fluorescence microscopy with optical sectioning, digital imaging, and numerical deconvolution techniques have been utilized. Results demonstrate that within the first minutes of flow application nuclear calcium is increasing. In the same time frame whole cell height and nuclear height are reduced by about 1 microm. Whole cell height changes may facilitate reduction of shear stress gradients on the luminal surface, whereas nuclear structural changes may be important for modulating endothelial growth rate and metabolism. To study the role of the cytoskeleton in these responses, endothelial cells have been treated with specific disrupters (acrylamide, cytochalasin D, and colchicine) of each of the cytoskeleton elements (intermediate filaments, microfilaments, and microtubules, respectively). None of these compounds had any effect on the shear-induced calcium response. Cytochalasin D and acrylamide did not affect the shear-induced nuclear morphology changes. Colchicine, however, completely abrogated the response, indicating that microtubules may be implicated in force transmission from the plasma membrane to the nucleus. A pedagogical model based on tensegrity theory principles is presented that is consistent with the results on the 3D endothelial morphology.

Inter-trabecular angle: A parameter of trabecular bone architecture in the human proximal femur that reveals underlying topological motifs.

PubMed

Reznikov, Natalie; Chase, Hila; Ben Zvi, Yehonatan; Tarle, Victoria; Singer, Matthew; Brumfeld, Vlad; Shahar, Ron; Weiner, Steve

2016-10-15

Trabecular bone is an intricate 3D network of struts and plates. Although the structure-function relations in trabecular bone have been studied since the time of Julius Wolff, controversy still exists regarding the architectural parameters responsible for its stability and resilience. We present a parameter that measures the angle between two connected trabeculae - the Inter-Trabecular Angle (ITA). We studied the ITA values derived from μCT scans of different regions of the proximal femora of 5 individuals of different age and sex. We show that the ITA angle distribution of nodes with 3 connecting trabeculae has a mean close to 120°, nodes with 4 connecting trabeculae has a mean close to 109° and nodes of higher connectivity have mean ITA values around 100°. This tendency to spread the ITAs around geometrically symmetrical motifs is highly conserved. The implication is that the ITAs are optimized such that the smallest amount of material spans the maximal 3D volume, and possibly by so doing trabecular bone might be better adapted to multidirectional loading. We also draw a parallel between trabecular bone and tensegrity structures - where lightweight, resilient and stable tetrahedron-based shapes contribute to strain redistribution amongst all the elements and to collective impact dampening. The Inter-Trabecular Angle (ITA) is a new topological parameter of trabecular bone. The ITA characterizes the way trabeculae connect with each other at nodes, regardless of their thickness and shape. The mean ITA value of nodes with 3 trabeculae is close to 120°, of nodes with 4 trabeculae is just below 109°, and the mean ITA of nodes with 5 and more trabeculae is around 100°. Thus the connections of trabeculae trend towards adopting symmetrical shapes. This implies that trabeculae can maximally span 3D space using the minimal amount of material. We draw a parallel between this motif and the concept of tensegrity - an engineering premise to which many living creatures conform at multiple levels of organization. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Spectacularly robust! Tensegrity principle explains the mechanical strength of the avian lung.

PubMed

Maina, J N

2007-01-15

Among the air-breathing vertebrates, the respiratory system of birds, the lung-air sac system, is remarkably complex and singularly efficient. The most perplexing structural property of the avian lung pertains to its exceptional mechanical strength, especially that of the minuscule terminal respiratory units, the air- and the blood capillaries. In different species of birds, the air capillaries range in diameter from 3 to 20 micro m: the blood capillaries are in all cases relatively smaller. Over and above their capacity to withstand enormous surface tension forces at the air-tissue interface, the air capillaries resist mechanical compression (parabronchial distending pressure) as high as 20 cm H(2)O (2 kPa). The blood capillaries tolerate a pulmonary arterial vascular pressure of 24.1 mmHg (3.2 kPa) and vascular resistance of 22.5 mmHg (3 kPa) without distending. The design of the avian respiratory system fundamentally stems from the rigidity (strength) of the lung. The gas exchanger (the lung) is uncoupled from the ventilator (the air sacs), allowing the lung (the paleopulmonic parabronchi) to be ventilated continuously and unidirectionally by synchronized bellows like action of the air sacs. Since during the ventilation of the lung the air capillaries do not have to be distended (dilated), i.e., surface tension force does not have to be overcome (as would be the case if the lung was compliant), extremely intense subdivision of the exchange tissue was possible. Minuscule terminal respiratory units developed, producing a vast respiratory surface area in a limited lung volume. I make a case that a firm (rigid) rib cage, a lung tightly held by the ribs and the horizontal septum, a lung directly attached to the trunk, specially formed and compactly arranged parabronchi, intertwined atrial muscles, and tightly set air capillaries and blood capillaries form an integrated hierarchy of discrete network system of tension and compression, a tensegrity (tensional integrity) array, which absorbs, transmits, and dissipates stress, stabilizing (strengthening) the lung and its various structural components.

Time lapse microscopy of temperature control during self-assembly of 3D DNA crystals

NASA Astrophysics Data System (ADS)

Conn, Fiona W.; Jong, Michael Alexander; Tan, Andre; Tseng, Robert; Park, Eunice; Ohayon, Yoel P.; Sha, Ruojie; Mao, Chengde; Seeman, Nadrian C.

2017-10-01

DNA nanostructures are created by exploiting the high fidelity base-pairing interactions of double-stranded branched DNA molecules. These structures present a convenient medium for the self-assembly of macroscopic 3D crystals. In some self-assemblies in this system, crystals can be formed by lowering the temperature, and they can be dissolved by raising it. The ability to monitor the formation and melting of these crystals yields information that can be used to monitor crystal formation and growth. Here, we describe the development of an inexpensive tool that enables direct observation of the crystal growth process as a function of both time and temperature. Using the hanging-drop crystallization of the well-characterized 2-turn DNA tensegrity triangle motif for our model system, its response to temperature has been characterized visually.

Microscopic and histochemical manifestations of hyaline cartilage dynamics.

PubMed

Malinin, G I; Malinin, T I

1999-01-01

Structure and function of hyaline cartilages has been the focus of many correlative studies for over a hundred years. Much of what is known regarding dynamics and function of cartilage constituents has been derived or inferred from biochemical and electron microscopic investigations. Here we show that in conjunction with ultrastructural, and high-magnification transmission light and polarization microscopy, the well-developed histochemical methods are indispensable for the analysis of cartilage dynamics. Microscopically demonstrable aspects of cartilage dynamics include, but are not limited to, formation of the intracellular liquid crystals, phase transitions of the extracellular matrix and tubular connections between chondrocytes. The role of the interchondrocytic liquid crystals is considered in terms of the tensegrity hypothesis and non-apoptotic cell death. Phase transitions of the extracellular matrix are discussed in terms of self-alignment of chondrons, matrix guidance pathways and cartilage growth in the absence of mitosis. The possible role of nonenzymatic glycation reactions in cartilage dynamics is also reviewed.

Conception and development of the Second Life® Embryo Physics Course.

PubMed

Gordon, Richard

2013-06-01

The study of embryos with the tools and mindset of physics, started by Wilhelm His in the 1880s, has resumed after a hiatus of a century. The Embryo Physics Course convenes online allowing interested researchers and students, who are scattered around the world, to gather weekly in one place, the virtual world of Second Life®. It attracts people from a wide variety of disciplines and walks of life: applied mathematics, artificial life, bioengineering, biophysics, cancer biology, cellular automata, civil engineering, computer science, embryology, electrical engineering, evolution, finite element methods, history of biology, human genetics, mathematics, molecular developmental biology, molecular biology, nanotechnology, philosophy of biology, phycology, physics, self-reproducing systems, stem cells, tensegrity structures, theoretical biology, and tissue engineering. Now in its fifth year, the Embryo Physics Course provides a focus for research on the central question of how an embryo builds itself.

3D DNA Origami Crystals.

PubMed

Zhang, Tao; Hartl, Caroline; Frank, Kilian; Heuer-Jungemann, Amelie; Fischer, Stefan; Nickels, Philipp C; Nickel, Bert; Liedl, Tim

2018-05-18

3D crystals assembled entirely from DNA provide a route to design materials on a molecular level and to arrange guest particles in predefined lattices. This requires design schemes that provide high rigidity and sufficiently large open guest space. A DNA-origami-based "tensegrity triangle" structure that assembles into a 3D rhombohedral crystalline lattice with an open structure in which 90% of the volume is empty space is presented here. Site-specific placement of gold nanoparticles within the lattice demonstrates that these crystals are spacious enough to efficiently host 20 nm particles in a cavity size of 1.83 × 10 5 nm 3 , which would also suffice to accommodate ribosome-sized macromolecules. The accurate assembly of the DNA origami lattice itself, as well as the precise incorporation of gold particles, is validated by electron microscopy and small-angle X-ray scattering experiments. The results show that it is possible to create DNA building blocks that assemble into lattices with customized geometry. Site-specific hosting of nano objects in the optically transparent DNA lattice sets the stage for metamaterial and structural biology applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulated Microgravity Induced Cytoskeletal Rearrangements are Modulated by Protooncogenes

NASA Technical Reports Server (NTRS)

Melhado, C. D.; Sanford, G. L.; Bosah, F.; Harris-Hooker, S.

1998-01-01

Microgravity is the environment living systems encounter during space flight and gravitational unloading is the effect of this environment on living systems. The cell, being a multiphasic chemical system, is a useful starting point to study the potential impact of gravity unloading on physiological function. In the absence of gravity, sedimentation of organelles including chromosomes, mitochondria, nuclei, the Golgi apparatus, vacuoles, and the endoplasmic reticulum may be affected. Most of these organelles, however, are somewhat held in place by cytoskeleton. Hansen and Igber suggest that intermediate filaments act to stabilize the nuleus against rotational movement, and integrate cell and nuclear structure. The tensegrity theory supports the idea that mechanical or physical forces alters the cytoskeletal structures of a cell resulting in the changes in cell: matrix interactions and receptor-signaling coupling. This type of stress to the cytoskeleton may be largely responsible regulating cell shape, growth, movement and metabolism. Mouse MC3T3 El cells under microgravity exhibited significant cytoskeletal changes and alterations in cell growth. The alterations in cytoskeleton architecture may be due to changes in the expression of actin related proteins or integrins. Philopott and coworkers reported on changes in the distribution of microtubule and cytoskeleton elements in the cells of heart tissue from space flight rats and those centrifuged at 1.7g. Other researchers have showed that microgravity reduced EGF-induced c-fos and c-jun expression compared to 1 g controls. Since c-fos and c-jun are known regulators of cell growth, it is likely that altered signal transduction involving protooncogenes may play a crucial role in the reduced growth and alterations in cytoskeletal arrangements found during space flight. It is clear that a microgravity environment induces a number of changes in cell shape, cell surface molecules, gene expression, and cytoskeletal reorganization. However the underlying mechanism for these cellular changes have not been clearly defined. We examined alterations in endothelial migration, and cytoskeleton architecture (microfilamentous f-actin and vimentin-rich- intermediate filaments) following wounding under simulated microgravity. We also examined the possibility that altered signal transduction pathways, involving protooncogenes, may play a crucial role in microgravity-induced retardation of cell migration and alterations in cytoskeletal organization. We hypothesize that, based on the tensegrity theory, cytoskeletal organization respond to gravitational unloading and through this response, cell behavior, function and gene expression are modified.

13th Annual Conference on the Foundations of Nanoscience (FNANO 2016) Held in Snowbird Cliff Lodge, Snowbird, Utah, April 11-14, 2016

DTIC Science & Technology

2017-01-30

Friedrich C . Simmel Salt and Temperature Dependence of Shape and Interhelical Spacing of DNA Origami Nanostructures Studied by Small Angle X-Ray Scattering...Nuclear Pore Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Patrick D. Ellis, Qi Shen, Thomas J . Melia, C . Patrick...and C . Mao, “Tensegrity: Construction of rigid DNA triangles with flexible four-arm junctions,” J . Am. Chem. Soc., 126, 2324 (2004). [3] J . Zheng et

Functionalizing Designer DNA Crystals

NASA Astrophysics Data System (ADS)

Chandrasekaran, Arun Richard

Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine nucleotides is usually pH dependent (pH < 6) four different TFOs were examined: TFO-1 was unmodified while TFOs 2-4 contained additional stabilizing analogues capable of extending triplex formation to pH 7. In addition, each of the TFOs contained a Cy5 dye at the 5'-end of the oligonucleotide to aid in characterization of TFO binding - crystals were obtained with all four variations of TFOs. Formation of DNA triplex in the motif was characterized by an electrophoretic mobility shift assay (EMSA), UV melting studies and FRET. Crystals containing TFO-1 (unmodified) and TFO-2 (with 2'-amino ethoxy modification) were isolated and flash-frozen in liquid nitrogen for X-ray data collection at beam line NSLS-X25. X-ray data was also collected for crystals of the 3-turn triangle without any TFO bound to it. Difference maps were done between the crystals with TFO against the one without to identify any additional electron density corresponding to the third strand in the triplex binding region. The data from the crystal containing TFO-2 was used to further analyze if the additional density can match the expected position of the TFO on the triangle motif. Since the additional density did not correspond to the entire binding region, 2Fo-Fc, 3Fo-2Fc and 4Fo-3Fc maps were done to check for missing pieces of the electron density. From the resulting 2Fo-Fc map, the asymmetric unit from the 3-turn triangle (31-bp duplex model based on previous structure 3UBI) was inserted into the density as a reference. However, the electron density corresponding to the TFO was still not continuous throughout the 13-nt triplex binding region and allowed only a partial fit of the TFO. The third nucleotide in positions 1, 3, 4, 6, 7 were fit into the density in the major groove of the underlying duplex with proper triplex configuration. The third chapter describes the triplex approach to position a functional group (the UV cross-linking agent psoralen) within a pre-formed DNA motif. Triplex formation and psoralen cross-linking of the motif were analyzed by native and denaturing gel electrophoresis respectively. Motifs containing the Psoralen-TFO were also successfully crystallized and the crosslinking shown by analyzing the denatured crystals on a gel. The end goal would be to form a crosslinked designed DNA crystal that can diffract to a higher resolution. The fourth chapter describes the use of serial femtosecond crystallography for structure determination of designed DNA lattices. X-ray diffraction data from self-assembled 3D DNA microcrystals were collected from a stream of crystals in solution. Serial femtosecond crystallography eliminates the need for large crystals and the need for freezing, thus overcoming any associated crystal defects and radiation damage. Self-assembled nano/microcrystals were successfully made and were diffracted at room temperature. The best diffraction was from the 1-nt SE motif to an extent of 3.5 A in resolution.

Gravity: one of the driving forces for evolution.

PubMed

Volkmann, D; Baluska, F

2006-12-01

Mechanical load is 10(3) larger for land-living than for water-living organisms. As a consequence, antigravitational material in form of compound materials like lignified cell walls in plants and mineralised bones in animals occurs in land-living organisms preferentially. Besides cellulose, pectic substances of plant cell walls seem to function as antigravitational material in early phases of plant evolution and development. A testable hypothesis including vesicular recycling processes into the tensegrity concept is proposed for both sensing of gravitational force and responding by production of antigravitational material at the cellular level.

Electron Beam Irradiated Intercalated CNT Yarns For Aerospace Applications

NASA Technical Reports Server (NTRS)

Waters, Deborah L.; Gaier, James R.; Williams, Tiffany S.; Lopez Calero, Johnny E.; Ramirez, Christopher; Meador, Michael A.

2015-01-01

Multi-walled CNT yarns have been experimentally and commercially created to yield lightweight, high conductivity fibers with good tensile properties for application as electrical wiring and multifunctional tendons. Multifunctional tendons are needed as the cable structures in tensegrity robots for use in planetary exploration. These lightweight robust tendons can provide mechanical strength for movement of the robot in addition to power distribution and data transmission. In aerospace vehicles, such as Orion, electrical wiring and harnessing mass can approach half of the avionics mass. Use of CNT yarns as electrical power and data cables could reduce mass of the wiring by thirty to seventy percent. These fibers have been intercalated with mixed halogens to increase their specific electrical conductivity to that near copper. This conductivity, combined with the superior strength and fatigue resistance makes it an attractive alternative to copper for wiring and multifunctional tendon applications. Electron beam irradiation has been shown to increase mechanical strength in pristine CNT fibers through increased cross-linking. Both pristine and intercalated CNT yarns have been irradiated using a 5-megavolt electron beam for various durations and the conductivities and tensile properties will be discussed. Structural information obtained using a field emission scanning electron microscope, energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy will correlate microstructural details with bulk properties.

Cell prestress. I. Stiffness and prestress are closely associated in adherent contractile cells

NASA Technical Reports Server (NTRS)

Wang, Ning; Tolic-Norrelykke, Iva Marija; Chen, Jianxin; Mijailovich, Srboljub M.; Butler, James P.; Fredberg, Jeffrey J.; Stamenovic, Dimitrije; Ingber, D. E. (Principal Investigator)

2002-01-01

The tensegrity hypothesis holds that the cytoskeleton is a structure whose shape is stabilized predominantly by the tensile stresses borne by filamentous structures. Accordingly, cell stiffness must increase in proportion with the level of the tensile stress, which is called the prestress. Here we have tested that prediction in adherent human airway smooth muscle (HASM) cells. Traction microscopy was used to measure the distribution of contractile stresses arising at the interface between each cell and its substrate; this distribution is called the traction field. Because the traction field must be balanced by tensile stresses within the cell body, the prestress could be computed. Cell stiffness (G) was measured by oscillatory magnetic twisting cytometry. As the contractile state of the cell was modulated with graded concentrations of relaxing or contracting agonists (isoproterenol or histamine, respectively), the mean prestress ((t)) ranged from 350 to 1,900 Pa. Over that range, cell stiffness increased linearly with the prestress: G (Pa) = 0.18(t) + 92. While this association does not necessarily preclude other interpretations, it is the hallmark of systems that secure shape stability mainly through the prestress. Regardless of mechanism, these data establish a strong association between stiffness of HASM cells and the level of tensile stress within the cytoskeleton.

From molecular to macroscopic via the rational design of a self-assembled 3D DNA crystal.

PubMed

Zheng, Jianping; Birktoft, Jens J; Chen, Yi; Wang, Tong; Sha, Ruojie; Constantinou, Pamela E; Ginell, Stephan L; Mao, Chengde; Seeman, Nadrian C

2009-09-03

We live in a macroscopic three-dimensional (3D) world, but our best description of the structure of matter is at the atomic and molecular scale. Understanding the relationship between the two scales requires a bridge from the molecular world to the macroscopic world. Connecting these two domains with atomic precision is a central goal of the natural sciences, but it requires high spatial control of the 3D structure of matter. The simplest practical route to producing precisely designed 3D macroscopic objects is to form a crystalline arrangement by self-assembly, because such a periodic array has only conceptually simple requirements: a motif that has a robust 3D structure, dominant affinity interactions between parts of the motif when it self-associates, and predictable structures for these affinity interactions. Fulfilling these three criteria to produce a 3D periodic system is not easy, but should readily be achieved with well-structured branched DNA motifs tailed by sticky ends. Complementary sticky ends associate with each other preferentially and assume the well-known B-DNA structure when they do so; the helically repeating nature of DNA facilitates the construction of a periodic array. It is essential that the directions of propagation associated with the sticky ends do not share the same plane, but extend to form a 3D arrangement of matter. Here we report the crystal structure at 4 A resolution of a designed, self-assembled, 3D crystal based on the DNA tensegrity triangle. The data demonstrate clearly that it is possible to design and self-assemble a well-ordered macromolecular 3D crystalline lattice with precise control.

3D MRI Modeling of Thin and Spatially Complex Soft Tissue Structures without Shrinkage: Lamprey Myosepta as an Example.

PubMed

Wood, Bradley M; Jia, Guang; Carmichael, Owen; McKlveen, Kevin; Homberger, Dominique G

2018-05-12

3D imaging techniques enable the non-destructive analysis and modeling of complex structures. Among these, MRI exhibits good soft tissue contrast, but is currently less commonly used for non-clinical research than x-ray CT, even though the latter requires contrast-staining that shrinks and distorts soft tissues. When the objective is the creation of a realistic and complete 3D model of soft tissue structures, MRI data are more demanding to acquire and visualize and require extensive post-processing because they comprise non-cubic voxels with dimensions that represent a trade-off between tissue contrast and image resolution. Therefore, thin soft tissue structures with complex spatial configurations are not always visible in a single MRI dataset, so that standard segmentation techniques are not sufficient for their complete visualization. By using the example of the thin and spatially complex connective tissue myosepta in lampreys, we developed a workflow protocol for the selection of the appropriate parameters for the acquisition of MRI data and for the visualization and 3D modeling of soft tissue structures. This protocol includes a novel recursive segmentation technique for supplementing missing data in one dataset with data from another dataset to produce realistic and complete 3D models. Such 3D models are needed for the modeling of dynamic processes, such as the biomechanics of fish locomotion. However, our methodology is applicable to the visualization of any thin soft tissue structures with complex spatial configurations, such as fasciae, aponeuroses, and small blood vessels and nerves, for clinical research and the further exploration of tensegrity. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Mechanotransduction through Cytoskeleton

NASA Technical Reports Server (NTRS)

Ingber, Donald

2002-01-01

The goal of this project was to characterize the molecular mechanism by which cells recognize and respond to physical forces in their local environment. The project was based on the working hypothesis that cells sense mechanical stresses, such as those due to gravity, through their cell surface adhesion receptors (e.g., integrins) and that they respond as a result of structural arrangements with their internal cytoskeleton (CSK) which are orchestrated through use of tensegrity architecture. In this project, we carried out studies to define the architectural and molecular basis of cellular mechanotransduction. Our major goal was to define the molecular pathway that mediates mechanical force transfer between integrins and the CSK and to determine how mechanical deformation of integrin-CSK linkages is transduced into a biochemical response. Elucidation of the mechanism by which cells sense mechanical stresses through integrins and translate them into a biochemical response should help us to understand the molecular basis of the cellular response to gravity as well as many other forms of mechanosensation and tissue regulation. The specific aims of this proposal were: 1. To define the molecular basis of mechanical coupling between integrins, vinculin, and the actin CSK; 2. To develop a computer simulation of how mechanical stresses alter CSK structure and test this model in living cells; 3. To determine how mechanical deformation of integrin-CSK linkages is transduced into a biochemical response.

Mechanotransduction as an Adaptation to Gravity

PubMed Central

Najrana, Tanbir; Sanchez-Esteban, Juan

2016-01-01

Gravity has played a critical role in the development of terrestrial life. A key event in evolution has been the development of mechanisms to sense and transduce gravitational force into biological signals. The objective of this manuscript is to review how living organisms on Earth use mechanotransduction as an adaptation to gravity. Certain cells have evolved specialized structures, such as otoliths in hair cells of the inner ear and statoliths in plants, to respond directly to the force of gravity. By conducting studies in the reduced gravity of spaceflight (microgravity) or simulating microgravity in the laboratory, we have gained insights into how gravity might have changed life on Earth. We review how microgravity affects prokaryotic and eukaryotic cells at the cellular and molecular levels. Genomic studies in yeast have identified changes in genes involved in budding, cell polarity, and cell separation regulated by Ras, PI3K, and TOR signaling pathways. Moreover, transcriptomic analysis of late pregnant rats have revealed that microgravity affects genes that regulate circadian clocks, activate mechanotransduction pathways, and induce changes in immune response, metabolism, and cells proliferation. Importantly, these studies identified genes that modify chromatin structure and methylation, suggesting that long-term adaptation to gravity may be mediated by epigenetic modifications. Given that gravity represents a modification in mechanical stresses encounter by the cells, the tensegrity model of cytoskeletal architecture provides an excellent paradigm to explain how changes in the balance of forces, which are transmitted across transmembrane receptors and cytoskeleton, can influence intracellular signaling pathways and gene expression. PMID:28083527

Mechanotransduction as an Adaptation to Gravity.

PubMed

Najrana, Tanbir; Sanchez-Esteban, Juan

2016-01-01

Gravity has played a critical role in the development of terrestrial life. A key event in evolution has been the development of mechanisms to sense and transduce gravitational force into biological signals. The objective of this manuscript is to review how living organisms on Earth use mechanotransduction as an adaptation to gravity. Certain cells have evolved specialized structures, such as otoliths in hair cells of the inner ear and statoliths in plants, to respond directly to the force of gravity. By conducting studies in the reduced gravity of spaceflight (microgravity) or simulating microgravity in the laboratory, we have gained insights into how gravity might have changed life on Earth. We review how microgravity affects prokaryotic and eukaryotic cells at the cellular and molecular levels. Genomic studies in yeast have identified changes in genes involved in budding, cell polarity, and cell separation regulated by Ras, PI3K, and TOR signaling pathways. Moreover, transcriptomic analysis of late pregnant rats have revealed that microgravity affects genes that regulate circadian clocks, activate mechanotransduction pathways, and induce changes in immune response, metabolism, and cells proliferation. Importantly, these studies identified genes that modify chromatin structure and methylation, suggesting that long-term adaptation to gravity may be mediated by epigenetic modifications. Given that gravity represents a modification in mechanical stresses encounter by the cells, the tensegrity model of cytoskeletal architecture provides an excellent paradigm to explain how changes in the balance of forces, which are transmitted across transmembrane receptors and cytoskeleton, can influence intracellular signaling pathways and gene expression.

Mechanotransduction across the cell surface and through the cytoskeleton

NASA Technical Reports Server (NTRS)

Wang, N.; Butler, J. P.; Ingber, D. E.

1993-01-01

Mechanical stresses were applied directly to cell surface receptors with a magnetic twisting device. The extracellular matrix receptor, integrin beta 1, induced focal adhesion formation and supported a force-dependent stiffening response, whereas nonadhesion receptors did not. The cytoskeletal stiffness (ratio of stress to strain) increased in direct proportion to the applied stress and required intact microtubules and intermediate filaments as well as microfilaments. Tensegrity models that incorporate mechanically interdependent struts and strings that reorient globally in response to a localized stress mimicked this response. These results suggest that integrins act as mechanoreceptors and transmit mechanical signals to the cytoskeleton. Mechanotransduction, in turn, may be mediated simultaneously at multiple locations inside the cell through force-induced rearrangements within a tensionally integrated cytoskeleton.

Fog collectors and collection techniques

NASA Astrophysics Data System (ADS)

Höhler, I.; Suau, C.

2010-07-01

The earth sciences taught that due to the occurrence of water in three phases: gas, liquid and solid, solar energy keeps the hydrological cycle going, shaping the earth surface while regulating the climate and thus allowing smart technologies to interfere in the natural process by rerouting water and employing its yield for natural and human environments’ subsistence. This is the case of traditional fog collectors implemented by several researchers along the Atacama Desert since late ’50s such as vertical tensile mesh or macro-diamonds structures. Nevertheless, these basic prototypes require to be upgraded, mainly through new shapes, fabrics and frameworks’ types by following the principles of lightness, transformability, portability and polyvalence. The vertical canvas of conventional fog collectors contain too much stressed at each joints and as result it became vulnerable. Our study constitutes a research by design of two fog-trap devices along the Atacama Desert. Different climatic factors influence the efficiency of fog harvesting. In order to increase yield of collected fog water, we need to establish suitable placements that contain high rates of fog’s accumulation. As important as the location is also the building reliability of these collectors that will be installed. Their frames and skins have to be adjustable to the wind direction and resistant against strong winds and rust. Its fabric need to be more hydrophobic, elastic and with light colours to ease dripping/drainage and avoid ultra-violet deterioration. In addition, meshes should be well-tensed and frames well-embraced too. In doing so we have conceived two fog collectors: DropNet© (Höhler) and FogHive© (Suau). These designs explore climatic design parameters combined with the agile structural principles of Tensegrity and Geodesic widely developed by Bucky Fuller and Frei Otto. The research methods mainly consisted of literature review; fieldwork; comparative analysis of existing fog collection’s techniques and climatic design simulations. DropNet© is a lightweight fog collector kit -a standing-alone web- resistant against very strong winds. It is constructed with an elastic mesh according to the required tension. Apart from this, it is ease to be transported, assemble and relocated due to its tent-like construction. As a flexible construction it can be installed on flatten or uneven grounds. FogHive© is a modular space-frame, fully wrapped with a light waxy mesh, that can collect water fog and also performs like a shading/cooling device and a soil humidifier for greenery and potential inhabitation. Its body consists of a deployable polygonal structure with an adjustable polyvalent membrane which performs as water repellent skin (facing prevailing winds) and shading device facing Equator. In addition, a domestic wind turbine is installed within the structural frame to provide autonomous electrification. Both models have great applicability to provide drinking water in remote place and also irrigating water to repair or re-establish flora. Water collector, filtering (purification) and irrigation network are designed with appropriate materials and techniques.

Design Concepts for the Generation-X Mission

NASA Astrophysics Data System (ADS)

Lillie, Charles F.; Dailey, D.; Danner, R.; Shropshire, D.; Pearson, D.

2009-09-01

The Generation-X mission, proposed by Roger Brissenden at SAO, is one of the Advanced Strategic Mission Concepts that NASA is considering for development in the post-2020 time period. As currently conceived Gen-X would be a follow-on to the International X-ray Observatory (IXO), with a collecting area ≥ 50 m^2, 60-m focal length and 0.1 arc-second spatial resolution, which would be launched in ˜2030 with an Ares V Cargo Launch Vehicle to an L2 orbit. Our design concept assumes an Ares V with a 10-m diameter, 1,400 m^3 volume fairing (or an equivalent launch vehicle) will be developed for NASA's exploration program. The key features of this design include a 16-m diameter deployable x-ray mirror provides a collecting area of 136 m^2; a 60-m deployable optical bench which utilizes a Tensegrity structure to achieve high stiffness with low mass; and adaptive grazing incidence optics. Gen-X's combination of large collecting area and high spatial resolution will provide 4 to 5 orders of magnitude greater sensitivity than IXO, enabling scientists to study the formation and growth of the first black holes at z ≈ 8-15 with 0.1 to 10 keV fluxes of ≈ 10-20 erg cm^{-2}s^{-1}.

Design Concepts for the Generation-X Mission

NASA Astrophysics Data System (ADS)

Lillie, Charles F.; Dailey, D.; Danner, R.; Pearson, D.; Shropshire, D.

2010-03-01

The Generation-X mission, proposed by Roger Brissenden at SAO, is one of the Advanced Strategic Mission Concepts that NASA is considering for development in the post-2020 time period. As currently conceived Gen-X would be a follow-on to the International X-ray Observatory (IXO), with a collecting area ≥ 50 m2, 60-m focal length and 0.1 arc-second spatial resolution, which would be launched in 2030 with an Ares V Cargo Launch Vehicle to an L2 orbit. Our design concept assumes an Ares V with a 10-m diameter, 1,400 m3 volume fairing (or an equivalent launch vehicle) will be developed for NASA's exploration program. The key features of this design include a 16-m diameter deployable x-ray mirror provides a collecting area of 136 m2 a 60-m deployable optical bench which utilizes a Tensegrity structure to achieve high stiffness with low mass; and adaptive grazing incidence optics. Gen-X's combination of large collecting area and high spatial resolution will provide 4 to 5 orders of magnitude greater sensitivity than IXO, enabling scientists to study the formation and growth of the first black holes at z ≈ 8-15 with 0.1 to 10 keV fluxes of ≈ 10-20 erg cm-2s-1.

Cytoskeletal Mechanics

NASA Astrophysics Data System (ADS)

Mofrad, Mohammad R. K.; Kamm, Roger D.

2011-08-01

1. Introduction and the biological basis for cell mechanics Mohammad R. K. Mofrad and Roger Kamm; 2. Experimental measurements of intracellular mechanics Paul Janmey and Christoph Schmidt; 3. The cytoskeleton as a soft glassy material Jeffrey Fredberg and Ben Fabry; 4. Continuum elastic or viscoelastic models for the cell Mohammad R. K. Mofrad, Helene Karcher and Roger Kamm; 5. Multiphasic models of cell mechanics Farshid Guuilak, Mansoor A. Haider, Lori A. Setton, Tod A. Laursen and Frank P. T. Baaijens; 6. Models of cytoskeletal mechanics based on tensegrity Dimitrije Stamenovic; 7. Cells, gels and mechanics Gerald H. Pollack; 8. Polymer-based models of cytoskeletal networks F. C. MacKintosh; 9. Cell dynamics and the actin cytoskeleton James L. McGrath and C. Forbes Dewey, Jr; 10. Active cellular motion: continuum theories and models Marc Herant and Micah Dembo; 11. Summary Mohammad R. K. Mofrad and Roger Kamm.

Rheological behavior of mammalian cells.

PubMed

Stamenović, D

2008-11-01

Rheological properties of living cells determine how cells interact with their mechanical microenvironment and influence their physiological functions. Numerous experimental studies have show that mechanical contractile stress borne by the cytoskeleton and weak power-law viscoelasticity are governing principles of cell rheology, and that the controlling physics is at the level of integrative cytoskeletal lattice properties. Based on these observations, two concepts have emerged as leading models of cytoskeletal mechanics. One is the tensegrity model, which explains the role of the contractile stress in cytoskeletal mechanics, and the other is the soft glass rheology model, which explains the weak power-law viscoelasticity of cells. While these two models are conceptually disparate, the phenomena that they describe are often closely associated in living cells for reasons that are largely unknown. In this review, we discuss current understanding of cell rheology by emphasizing the underlying biophysical mechanism and critically evaluating the existing rheological models.

CRUX: a Compliant Robotic Upper-Extremity eXosuit for Lightweight, Portable, Multi-DoF Muscular Augmentation

NASA Technical Reports Server (NTRS)

Lessard, Steven; Pansodtee, Pattawong; Robbins, Ash; Baltaxe-Admony, Leya Breanna; Teodorescu, Mircea; Kurniawan,Sri; Agogino, Adrian; Kurniawan, Sri

2017-01-01

Wearable robots can potentially offer their users enhanced stability and strength. These augmentations are ideally designed to actuate harmoniously with the users movements and provide extra force as needed. The creation of such robots, however, is particularly challenging due to the complexity of the underlying human body. In this paper, we present a compliant, robotic exosuit for upper-extremities called CRUX. This exosuit, inspired by tensegrity models of the human arm, features a lightweight (1.3 kg), flexible design for portability. We also show how CRUX maintains full flexibility of the upper-extremities for its users while providing multi- DoF augmentative strength to the major muscles of the arm, as evident by tracking the heart rate of an individual exercising said arm. Exosuits such as CRUX may be useful in physical therapy and in extreme environments where users are expected to exert their bodies to the fullest extent.

Cell prestress. II. Contribution of microtubules

NASA Technical Reports Server (NTRS)

Stamenovic, Dimitrije; Mijailovich, Srboljub M.; Tolic-Norrelykke, Iva Marija; Chen, Jianxin; Wang, Ning; Ingber, D. E. (Principal Investigator)

2002-01-01

The tensegrity model hypothesizes that cytoskeleton-based microtubules (MTs) carry compression as they balance a portion of cell contractile stress. To test this hypothesis, we used traction force microscopy to measure traction at the interface of adhering human airway smooth muscle cells and a flexible polyacrylamide gel substrate. The prediction is that if MTs balance a portion of contractile stress, then, upon their disruption, the portion of stress balanced by MTs would shift to the substrate, thereby causing an increase in traction. Measurements were done first in maximally activated cells (10 microM histamine) and then again after MTs had been disrupted (1 microM colchicine). We found that after disruption of MTs, traction increased on average by approximately 13%. Because in activated cells colchicine induced neither an increase in intracellular Ca(2+) nor an increase in myosin light chain phosphorylation as shown previously, we concluded that the observed increase in traction was a result of load shift from MTs to the substrate. In addition, energy stored in the flexible substrate was calculated as work done by traction on the deformation of the substrate. This result was then utilized in an energetic analysis. We assumed that cytoskeleton-based MTs are slender elastic rods supported laterally by intermediate filaments and that MTs buckle as the cell contracts. Using the post-buckling equilibrium theory of Euler struts, we found that energy stored during buckling of MTs was quantitatively consistent with the measured increase in substrate energy after disruption of MTs. This is further evidence supporting the idea that MTs are intracellular compression-bearing elements.

Mechanical signaling and the cellular response to extracellular matrix in angiogenesis and cardiovascular physiology

NASA Technical Reports Server (NTRS)

Ingber, Donald E.

2002-01-01

Great advances have been made in the identification of the soluble angiogenic factors, insoluble extracellular matrix (ECM) molecules, and receptor signaling pathways that mediate control of angiogenesis--the growth of blood capillaries. This review focuses on work that explores how endothelial cells integrate these chemical signals with mechanical cues from their local tissue microenvironment so as to produce functional capillary networks that exhibit specialized form as well as function. These studies have revealed that ECM governs whether an endothelial cell will switch between growth, differentiation, motility, or apoptosis programs in response to a soluble stimulus based on its ability to mechanically resist cell tractional forces and thereby produce cell and cytoskeletal distortion. Transmembrane integrin receptors play a key role in this mechanochemical transduction process because they both organize a cytoskeletal signaling complex within the focal adhesion and preferentially focus mechanical forces on this site. Molecular filaments within the internal cytoskeleton--microfilaments, microtubules, and intermediate filaments--also contribute to the cell's structural and functional response to mechanical stress through their role as discrete support elements within a tensegrity-stabilized cytoskeletal array. Importantly, a similar form of mechanical control also has been shown to be involved in the regulation of contractility in vascular smooth muscle cells and cardiac myocytes. Thus, the mechanism by which cells perform mechanochemical transduction and the implications of these findings for morphogenetic control are discussed in the wider context of vascular development and cardiovascular physiology.

TALC: a new deployable concept for a 20m far-infrared space telescope

NASA Astrophysics Data System (ADS)

Durand, Gilles; Sauvage, Marc; Bonnet, Aymeric; Rodriguez, Louis; Ronayette, Samuel; Chanial, Pierre; Scola, Loris; Révéret, Vincent; Aussel, Hervé; Carty, Michael; Durand, Matthis; Durand, Lancelot; Tremblin, Pascal; Pantin, Eric; Berthe, Michel; Martignac, Jérôme; Motte, Frédérique; Talvard, Michel; Minier, Vincent; Bultel, Pascal

2014-08-01

TALC, Thin Aperture Light Collector is a 20 m space observatory project exploring some unconventional optical solutions (between the single dish and the interferometer) allowing the resolving power of a classical 27 m telescope. With TALC, the principle is to remove the central part of the prime mirror dish, cut the remaining ring into 24 sectors and store them on top of one-another. The aim of this far infrared telescope is to explore the 600 μm to 100 μm region. With this approach we have shown that we can store a ring-telescope of outer diameter 20m and ring thickness of 3m inside the fairing of Ariane 5 or Ariane 6. The general structure is the one of a bicycle wheel, whereas the inner sides of the segments are in compression to each other and play the rule of a rim. The segments are linked to each other using a pantograph scissor system that let the segments extend from a pile of dishes to a parabolic ring keeping high stiffness at all time during the deployment. The inner corners of the segments are linked to a central axis using spokes as in a bicycle wheel. The secondary mirror and the instrument box are built as a solid unit fixed at the extremity of the main axis. The tensegrity analysis of this structure shows a very high stiffness to mass ratio, resulting into 3 Hz Eigen frequency. The segments will consist of two composite skins and honeycomb CFRP structure build by replica process. Solid segments will be compared to deformable segments using the controlled shear of the rear surface. The adjustment of the length of the spikes and the relative position of the side of neighbor segments let control the phasing of the entire primary mirror. The telescope is cooled by natural radiation. It is protected from sun radiation by a large inflatable solar screen, loosely linked to the telescope. The orientation is performed by inertia-wheels. This telescope carries a wide field bolometer camera using cryocooler at 0.3K as one of the main instruments. This telescope may be launched with an Ariane 6 rocket up to 800 km altitude, and use a plasma stage to reach the Lagrange 2 point within 18 month. The plasma propulsion stage is a serial unit also used in commercial telecommunication satellites. When the plasma launch is completed, the solar panels will be used to provide the power for communication, orientation and power the cryo-coolers for the instruments. The guide-line for development of this telescope is to use similar techniques and serial subsystems developed for the satellite industry. This is the only way to design and manufacture a large telescope at a reasonable cost.

Hepatitis B virus core protein allosteric modulators can distort and disrupt intact capsids.

PubMed

Schlicksup, Christopher John; Wang, Joseph Che-Yen; Francis, Samson; Venkatakrishnan, Balasubramanian; Turner, William W; VanNieuwenhze, Michael; Zlotnick, Adam

2018-01-29

Defining mechanisms of direct-acting antivirals facilitates drug development and our understanding of virus function. Heteroaryldihydropyrimidines (HAPs) inappropriately activate assembly of hepatitis B virus (HBV) core protein (Cp), suppressing formation of virions. We examined a fluorophore-labeled HAP, HAP-TAMRA. HAP-TAMRA induced Cp assembly and also bound pre-assembled capsids. Kinetic and spectroscopic studies imply that HAP-binding sites are usually not available but are bound cooperatively. Using cryo-EM, we observed that HAP-TAMRA asymmetrically deformed capsids, creating a heterogeneous array of sharp angles, flat regions, and outright breaks. To achieve high resolution reconstruction (<4 Å), we introduced a disulfide crosslink that rescued particle symmetry. We deduced that HAP-TAMRA caused quasi-sixfold vertices to become flatter and fivefold more angular. This transition led to asymmetric faceting. That a disordered crosslink could rescue symmetry implies that capsids have tensegrity properties. Capsid distortion and disruption is a new mechanism by which molecules like the HAPs can block HBV infection. © 2017, Schlicksup et al.

CRUX: A compliant robotic upper-extremity exosuit for lightweight, portable, multi-joint muscular augmentation.

PubMed

Lessard, Steven; Pansodtee, Pattawong; Robbins, Ash; Baltaxe-Admony, Leya Breanna; Trombadore, James M; Teodorescu, Mircea; Agogino, Adrian; Kurniawan, Sri

2017-07-01

Wearable robots can potentially offer their users enhanced stability and strength. These augmentations are ideally designed to actuate harmoniously with the user's movements and provide extra force as needed. The creation of such robots, however, is particularly challenging due to the underlying complexity of the human body. In this paper, we present a compliant, robotic exosuit for upper extremities called CRUX. This exosuit, inspired by tensegrity models of the human arm, features a lightweight (1.3 kg), flexible multi-joint design for portable augmentation. We also illustrate how CRUX maintains the full range of motion of the upper-extremities for its users while providing multi-DoF strength amplification to the major muscles of the arm, as evident by tracking the heart rate of an individual exercising said arm. Exosuits such as CRUX may be useful in physical therapy and in extreme environments where users are expected to exert their bodies to the fullest extent.

Hepatitis B virus core protein allosteric modulators can distort and disrupt intact capsids

PubMed Central

Schlicksup, Christopher John; Wang, Joseph Che-Yen; Francis, Samson; Venkatakrishnan, Balasubramanian; Turner, William W; VanNieuwenhze, Michael

2018-01-01

Defining mechanisms of direct-acting antivirals facilitates drug development and our understanding of virus function. Heteroaryldihydropyrimidines (HAPs) inappropriately activate assembly of hepatitis B virus (HBV) core protein (Cp), suppressing formation of virions. We examined a fluorophore-labeled HAP, HAP-TAMRA. HAP-TAMRA induced Cp assembly and also bound pre-assembled capsids. Kinetic and spectroscopic studies imply that HAP-binding sites are usually not available but are bound cooperatively. Using cryo-EM, we observed that HAP-TAMRA asymmetrically deformed capsids, creating a heterogeneous array of sharp angles, flat regions, and outright breaks. To achieve high resolution reconstruction (<4 Å), we introduced a disulfide crosslink that rescued particle symmetry. We deduced that HAP-TAMRA caused quasi-sixfold vertices to become flatter and fivefold more angular. This transition led to asymmetric faceting. That a disordered crosslink could rescue symmetry implies that capsids have tensegrity properties. Capsid distortion and disruption is a new mechanism by which molecules like the HAPs can block HBV infection. PMID:29377794

2D-DIGE proteomic analysis of mesenchymal stem cell cultured on the elasticity-tunable hydrogels.

PubMed

Kuboki, Thasaneeya; Kantawong, Fahsai; Burchmore, Richard; Dalby, Matthew J; Kidoaki, Satoru

2012-01-01

The present study focuses on mechanotransduction in mesenchymal stem cells (MSCs) in response to matrix elasticity. By using photocurable gelatinous gels with tunable stiffness, proteomic profiles of MSCs cultured on tissue culture plastic, soft (3 kPa) and stiff (52 kPa) matrices were deciphered using 2-dimensional differential in-gel analysis (2D-DIGE). The DIGE data, tied to immunofluorescence, indicated abundance and organization changes in the cytoskeletonal proteins as well as differential regulation of important signaling-related proteins, stress-responsing proteins and also proteins involved in collagen synthesis. The major CSK proteins including actin, tubulin and vimentin of the cells cultured on the gels were remarkably changed their expressions. Significant down-regulation of α-tubulin and β-actin can be observed on gel samples in comparison to the rigid tissue culture plates. The expression abundance of vimentin appeared to be highest in the MSCs cultured on hard gels. These results suggested that the substrate stiffness significantly affects expression balances in cytoskeletal proteins of MSCs with some implications to cellular tensegrity.

Tissue specific characterisation of Lim-kinase 1 expression during mouse embryogenesis

PubMed Central

Lindström, Nils O.; Neves, Carlos; McIntosh, Rebecca; Miedzybrodzka, Zosia; Vargesson, Neil; Collinson, J. Martin

2012-01-01

The Lim-kinase (LIMK) proteins are important for the regulation of the actin cytoskeleton, in particular the control of actin nucleation and depolymerisation via regulation of cofilin, and hence may control a large number of processes during development, including cell tensegrity, migration, cell cycling, and axon guidance. LIMK1/LIMK2 knockouts disrupt spinal cord morphogenesis and synapse formation but other tissues and developmental processes that require LIMK are yet to be fully determined. To identify tissues and cell-types that may require LIMK, we characterised the pattern of LIMK1 protein during mouse embryogenesis. We showed that LIMK1 displays an expression pattern that is temporally dynamic and tissue-specific. In several tissues LIMK1 is detected in cell-types that also express Wilms’ tumour protein 1 and that undergo transitions between epithelial and mesenchymal states, including the pleura, epicardium, kidney nephrons, and gonads. LIMK1 was also found in a subset of cells in the dorsal retina, and in mesenchymal cells surrounding the peripheral nerves. This detailed study of the spatial and temporal expression of LIMK1 shows that LIMK1 expression is more dynamic than previously reported, in particular at sites of tissue–tissue interactions guiding multiple developmental processes. PMID:21167960

Lightweight Multifunctional Planetary Probe for Extreme Environment Exploration and Locomotion

NASA Technical Reports Server (NTRS)

Bayandor, Javid (Principal Investigator); Schroeder, Kevin; Samareh, Jamshid

2017-01-01

The demand to explore new worlds requires the development of advanced technologies that enable landed science on uncertain terrains or in hard to reach locations. As a result, contemporary Entry, Descent, Landing, (EDL) and additional locomotion (EDLL) profiles are becoming increasingly more complex, with the introduction of lifting/guided entries, hazard avoidance on descent, and a plethora of landing techniques including airbags and the skycrane maneuver. The inclusion of each of these subsystems into a mission profile is associated with a substantial mass penalty. This report explores the new all-in-one entry vehicle concept, TANDEM, a new combined EDLL concept, and compares it to the current state of the art EDL systems. The explored system is lightweight and collapsible and provides the capacity for lifting/guided entry, guided descent, hazard avoidance, omnidirectional impact protection and surface locomotion without the aid of any additional subsystems. This Phase I study explored: 1. The capabilities and feasibility of the TANDEM concept as an EDLL vehicle. 2. Extensive impact analysis to ensure mission success in unfavorable landing conditions, and safe landing in Tessera regions. 3. Development of a detailed design for a conceptual mission to Venus. As a result of our work it was shown that: 1. TANDEM provides additional benefits over the Adaptive, Deployable Entry Placement Technology (ADEPT) including guided descent and surface locomotion, while reducing the mass by 38% compared to the ADEPT-VITaL mission. 2. Demonstrated that the design of tensegrity structures, and TANDEM specifically, grows linearly with an increase in velocity, which was previously unknown. 3. Investigation of surface impact revealed a promising results that suggest a properly configured TANDEM vehicle can safely land and preform science in the Tessera regions, which was previously labeled by the Decadal Survey as, largely inaccessible despite its high scientific interest. This work has already resulted in a NASA TM and will be submitted to the Journal of Spacecraft and Rockets.

Reward-Modulated Hebbian Plasticity as Leverage for Partially Embodied Control in Compliant Robotics

PubMed Central

Burms, Jeroen; Caluwaerts, Ken; Dambre, Joni

2015-01-01

In embodied computation (or morphological computation), part of the complexity of motor control is offloaded to the body dynamics. We demonstrate that a simple Hebbian-like learning rule can be used to train systems with (partial) embodiment, and can be extended outside of the scope of traditional neural networks. To this end, we apply the learning rule to optimize the connection weights of recurrent neural networks with different topologies and for various tasks. We then apply this learning rule to a simulated compliant tensegrity robot by optimizing static feedback controllers that directly exploit the dynamics of the robot body. This leads to partially embodied controllers, i.e., hybrid controllers that naturally integrate the computations that are performed by the robot body into a neural network architecture. Our results demonstrate the universal applicability of reward-modulated Hebbian learning. Furthermore, they demonstrate the robustness of systems trained with the learning rule. This study strengthens our belief that compliant robots should or can be seen as computational units, instead of dumb hardware that needs a complex controller. This link between compliant robotics and neural networks is also the main reason for our search for simple universal learning rules for both neural networks and robotics. PMID:26347645

NASA Tech Briefs, August 2004

NASA Technical Reports Server (NTRS)

2004-01-01

Topics covered include: Data Relay Board with Protocol for High-Speed, Free-Space Optical Communications; Software and Algorithms for Biomedical Image Data Processing and Visualization; Rapid Chemometric Filtering of Spectral Data; Prioritizing Scientific Data for Transmission; Determining Sizes of Particles in a Flow from DPIV Data; Faster Processing for Inverting GPS Occultation Data; FPGA-Based, Self-Checking, Fault-Tolerant Computers; Ultralow-Power Digital Correlator for Microwave Polarimetry; Grounding Headphones for Protection Against ESD; Lightweight Stacks of Direct Methanol Fuel Cells; Highly Efficient Vector-Inversion Pulse Generators; Estimating Basic Preliminary Design Performances of Aerospace Vehicles; Framework for Development of Object-Oriented Software; Analyzing Spacecraft Telecommunication Systems; Collaborative Planning of Robotic Exploration; Tools for Administration of a UNIX-Based Network; Preparing and Analyzing Iced Airfoils; Evaluating Performance of Components; Fuels Containing Methane of Natural Gas in Solution; Direct Electrolytic Deposition of Mats of MnxOy Nanowires; Bubble Eliminator Based on Centrifugal Flow; Inflatable Emergency Atmospheric-Entry Vehicles; Lightweight Deployable Mirrors with Tensegrity Supports; Centrifugal Adsorption Cartridge System; Ultrasonic Apparatus for Pulverizing Brittle Material; Transplanting Retinal Cells using Bucky Paper for Support; Using an Ultrasonic Instrument to Size Extravascular Bubbles; Coronagraphic Notch Filter for Raman Spectroscopy; On-the-Fly Mapping for Calibrating Directional Antennas; Working Fluids for Increasing Capacities of Heat Pipes; Computationally-Efficient Minimum-Time Aircraft Routes in the Presence of Winds; Liquid-Metal-Fed Pulsed Plasma Thrusters; Personal Radiation Protection System; and Attitude Control for a Solar-Sail Spacecraft.

Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight.

PubMed

Maina, John N

2017-08-01

Among the extant air-breathing vertebrates, the avian respiratory system is structurally the most complex and functionally the most efficient gas exchanger. Having been investigated for over four centuries, some aspects of its biology have been extremely challenging and highly contentious and others still remain unresolved. Here, while assessing the most recent findings, four notable aspects of the structure and function of the avian respiratory system are examined critically to highlight the questions, speculations, controversies and debates that have arisen from past research. The innovative techniques and experiments that were performed to answer particular research questions are emphasised. The features that are outlined here concern the arrangement of the airways, the path followed by the inspired air, structural features of the lung and the air and blood capillaries, and the level of cellular defence in the avian respiratory system. Hitherto, based on association with the proven efficiency of naturally evolved and human-made counter-current exchange systems rather than on definite experimental evidence, a counter-current gas exchange system was suggested to exist in the avian respiratory system and was used to explain its exceptional efficiency. However, by means of an elegant experiment in which the direction of the air-flow in the lung was reversed, a cross-current system was shown to be in operation instead. Studies of the arrangement of the airways and the blood vessels corroborated the existence of a cross-current system in the avian lung. While the avian respiratory system is ventilated tidally, like most other invaginated gas exchangers, the lung, specifically the paleopulmonic parabronchi, is ventilated unidirectionally and continuously in a caudocranial (back-to-front) direction by synchronized actions of the air sacs. The path followed by the inspired air in the lung-air sac system is now known to be controlled by a mechanism of aerodynamic valving and not by anatomical valves or sphincters, as was previously supposed. The structural strength of the air and blood capillaries is derived from: the interdependence between the air and blood capillaries; a tethering effect between the closely entwined respiratory units; the presence of epithelial-epithelial cell connections (retinacula or cross-bridges) that join the blood capillaries while separating the air capillaries; the abundance and intricate arrangement of the connective tissue elements, i.e. collagen, elastin, and smooth muscle fibres; the presence of type-IV collagen, especially in the basement membranes of the blood-gas barrier and the epithelial-epithelial cell connections; and a putative tensegrity state in the lung. Notwithstanding the paucity of free surface pulmonary macrophages, the respiratory surface of the avian lung is well protected from pathogens and particulates by an assortment of highly efficient phagocytic cells. In commercial poultry production, instead of weak pulmonary cellular defence, stressful husbandry practices such as overcrowding, force-feeding, and intense genetic manipulation for rapid weight gain and egg production may account for the reported susceptibility of birds to aerosol-transmitted diseases. © 2016 Cambridge Philosophical Society.

The origin of consistent protein structure refinement from structural averaging.

PubMed

Park, Hahnbeom; DiMaio, Frank; Baker, David

2015-06-02

Recent studies have shown that explicit solvent molecular dynamics (MD) simulation followed by structural averaging can consistently improve protein structure models. We find that improvement upon averaging is not limited to explicit water MD simulation, as consistent improvements are also observed for more efficient implicit solvent MD or Monte Carlo minimization simulations. To determine the origin of these improvements, we examine the changes in model accuracy brought about by averaging at the individual residue level. We find that the improvement in model quality from averaging results from the superposition of two effects: a dampening of deviations from the correct structure in the least well modeled regions, and a reinforcement of consistent movements towards the correct structure in better modeled regions. These observations are consistent with an energy landscape model in which the magnitude of the energy gradient toward the native structure decreases with increasing distance from the native state. Copyright © 2015 Elsevier Ltd. All rights reserved.

75 FR 16202 - Office of New Reactors; Interim Staff Guidance on Ensuring Hazard-Consistent Seismic Input for...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-31

... Staff Guidance on Ensuring Hazard-Consistent Seismic Input for Site Response and Soil Structure...-Consistent Seismic Input for Site Response and Soil Structure Interaction Analyses,'' (Agencywide Documents... Soil Structure Interaction Analyses,'' (ADAMS Accession No. ML092230455) to solicit public and industry...

First-principles study of low-spin LaCoO3 with structurally consistent Hubbard U

NASA Astrophysics Data System (ADS)

Hsu, H.; Umemoto, K.; Cococcioni, M.; Wentzcovitch, R.

2008-12-01

We use the local density approximation + Hubbard U (LDA+U) method to calculate the structural and electronic properties of low-spin LaCoO3. The Hubbard U is obtained by first principles and consistent with each fully-optimized atomic structure at different pressures. With structurally consistent U, the fully-optimized atomic structure agrees with experimental data better than the calculations with fixed or vanishing U. A discussion on how the Hubbard U affects the electronic and atomic structure of LaCoO3 is also given.

A Lightweight, Precision-Deployable, Optical Bench for High Energy Astrophysics Missions

NASA Astrophysics Data System (ADS)

Danner, Rolf; Dailey, D.; Lillie, C.

2011-09-01

The small angle of total reflection for X-rays, forcing grazing incidence optics with large collecting areas to long focal lengths, has been a fundamental barrier to the advancement of high-energy astrophysics. Design teams around the world have long recognized that a significant increase in effective area beyond Chandra and XMM-Newton requires either a deployable optical bench or separate X-ray optics and instrument module on formation flying spacecraft. Here, we show that we have in hand the components for a lightweight, precision-deployable optical bench that, through its inherent design features, is the affordable path to the next generation of imaging high-energy astrophysics missions. We present our plans for a full-scale engineering model of a deployable optical bench for Explorer-class missions. We intend to use this test article to raise the technology readiness level (TRL) of the tensegrity truss for a lightweight, precision-deployable optical bench for high-energy astrophysics missions from TRL 3 to TRL 5 through a set of four well-defined technology milestones. The milestones cover the architecture's ability to deploy and control the focal point, characterize the deployed dynamics, determine long-term stability, and verify the stowed load capability. Our plan is based on detailed design and analysis work and the construction of a first prototype by our team. Building on our prior analysis and the high TRL of the architecture components we are ready to move on to the next step. The key elements to do this affordably are two existing, fully characterized, flight-quality, deployable booms. After integrating them into the test article, we will demonstrate that our architecture meets the deployment accuracy, adjustability, and stability requirements. The same test article can be used to further raise the TRL in the future.

Consistency of Factor Structure on the Semantic Differential: An Analysis of Three Adult Samples.

ERIC Educational Resources Information Center

Sherry, David L.; Piotrowski, Chris

1986-01-01

The consistency of factor structure of Osgood's semantic differential was examined in three different adult samples, aged 18 to 87. Three different concepts were used: the University of West Florida, Myself, and Death. Results indicated consistency for the evaluation factor and moderate consistency for potency and activity. (Author/GDC)

Facet Theory and the Mapping Sentence As Hermeneutically Consistent Structured Meta-Ontology and Structured Meta-Mereology

PubMed Central

Hackett, Paul M. W.

2016-01-01

When behavior is interpreted in a reliable manner (i.e., robustly across different situations and times) its explained meaning may be seen to possess hermeneutic consistency. In this essay I present an evaluation of the hermeneutic consistency that I propose may be present when the research tool known as the mapping sentence is used to create generic structural ontologies. I also claim that theoretical and empirical validity is a likely result of employing the mapping sentence in research design and interpretation. These claims are non-contentious within the realm of quantitative psychological and behavioral research. However, I extend the scope of both facet theory based research and claims for its structural utility, reliability and validity to philosophical and qualitative investigations. I assert that the hermeneutic consistency of a structural ontology is a product of a structural representation's ontological components and the mereological relationships between these ontological sub-units: the mapping sentence seminally allows for the depiction of such structure. PMID:27065932

Hydrologic consistency as a basis for assessing complexity of monthly water balance models for the continental United States

NASA Astrophysics Data System (ADS)

Martinez, Guillermo F.; Gupta, Hoshin V.

2011-12-01

Methods to select parsimonious and hydrologically consistent model structures are useful for evaluating dominance of hydrologic processes and representativeness of data. While information criteria (appropriately constrained to obey underlying statistical assumptions) can provide a basis for evaluating appropriate model complexity, it is not sufficient to rely upon the principle of maximum likelihood (ML) alone. We suggest that one must also call upon a "principle of hydrologic consistency," meaning that selected ML structures and parameter estimates must be constrained (as well as possible) to reproduce desired hydrological characteristics of the processes under investigation. This argument is demonstrated in the context of evaluating the suitability of candidate model structures for lumped water balance modeling across the continental United States, using data from 307 snow-free catchments. The models are constrained to satisfy several tests of hydrologic consistency, a flow space transformation is used to ensure better consistency with underlying statistical assumptions, and information criteria are used to evaluate model complexity relative to the data. The results clearly demonstrate that the principle of consistency provides a sensible basis for guiding selection of model structures and indicate strong spatial persistence of certain model structures across the continental United States. Further work to untangle reasons for model structure predominance can help to relate conceptual model structures to physical characteristics of the catchments, facilitating the task of prediction in ungaged basins.

Is There Consistency between the Binding Affinity and Inhibitory Potential of Natural Polyphenols as α-amylase Inhibitors?

PubMed

Xu, Wei; Shao, Rong; Xiao, Jianbo

2016-07-26

The inhibitory potential of natural polyphenols for α-amylases has attracted great interests among researchers. The structure-affinity properties of natural polyphenols binding to α-amylase and the structure-activity relationship of dietary polyphenols inhibiting α-amylase were deeply investigated. There is a lack of consistency between the structure-affinity relationship and the structure-activity relationship of natural polyphenols as α-amylase inhibitors. Is it consistent between the binding affinity and inhibitory potential of natural polyphenols as with α-amylase inhibitors? It was found that the consistency between the binding affinity and inhibitory potential of natural polyphenols as with α-amylase inhibitors is not equivocal. For example, there is no consistency between the binding affinity and the inhibitory potential of quercetin and its glycosides as α-amylase inhibitors. However, catechins with higher α-amylase inhibitory potential exhibited higher affinity with α-amylase.

Catalytic distillation structure

DOEpatents

Smith, Jr., Lawrence A.

1984-01-01

Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

Joint representation of consistent structural and functional profiles for identification of common cortical landmarks.

PubMed

Zhang, Shu; Zhao, Yu; Jiang, Xi; Shen, Dinggang; Liu, Tianming

2018-06-01

In the brain mapping field, there have been significant interests in representation of structural/functional profiles to establish structural/functional landmark correspondences across individuals and populations. For example, from the structural perspective, our previous studies have identified hundreds of consistent DICCCOL (dense individualized and common connectivity-based cortical landmarks) landmarks across individuals and populations, each of which possess consistent DTI-derived fiber connection patterns. From the functional perspective, a large collection of well-characterized HAFNI (holistic atlases of functional networks and interactions) networks based on sparse representation of whole-brain fMRI signals have been identified in our prior studies. However, due to the remarkable variability of structural and functional architectures in the human brain, it is challenging for earlier studies to jointly represent the connectome-scale structural and functional profiles for establishing a common cortical architecture which can comprehensively encode both structural and functional characteristics across individuals. To address this challenge, we propose an effective computational framework to jointly represent the structural and functional profiles for identification of consistent and common cortical landmarks with both structural and functional correspondences across different brains based on DTI and fMRI data. Experimental results demonstrate that 55 structurally and functionally common cortical landmarks can be successfully identified.

Review of Aircraft Crash Structural Response Research.

DTIC Science & Technology

1982-08-01

structures consisting of conventional built-up metallic construction and those consisting of advanced composite materials were of interest. The latter...increasing importance. Some recent theoretical and experimental studies of the behavior of composite - material structures subjected to severe static...dynamic, and/or impact conditions are noted. Such topics as crashworthiness testing ot composite fuselage structures, the impact resistance of graphite and

Catalytic distillation structure

DOEpatents

Smith, L.A. Jr.

1984-04-17

Catalytic distillation structure is described for use in reaction distillation columns, and provides reaction sites and distillation structure consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and is present with the catalyst component in an amount such that the catalytic distillation structure consists of at least 10 volume % open space. 10 figs.

[Validity and internal consistency of the Maslach Burnout Inventory in Dental Students from Cartagena, Colombia].

PubMed

Simancas-Pallares, Miguel Angel; Fortich Mesa, Natalia; González Martínez, Farith Damián

To determine the internal consistency and content validity of the Maslach Burnout Inventory-Student Survey (MBI-SS) in dental students from Cartagena, Colombia. Scale validation study in 886 dental students from Cartagena, Colombia. Factor structure was determined through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Internal consistency was measured using the Cronbach's alpha coefficient. Analyses were performed using the Stata v.13.2 for Windows (Statacorp., USA) and Mplus v.7.31 for Windows (Muthén & Muthén, USA) software. Internal consistency was α=.806. The factor structure showed three that accounted for the 56.6% of the variance. CFA revealed: χ 2 =926.036; df=85; RMSEA=.106 (90%CI, .100-.112); CFI=.947; TLI=.934. The MBI showed an adequate internal consistency and a factor structure being consistent with the original proposed structure with a poor fit, which does not reflect adequate content validity in this sample. Copyright © 2016 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

Glued structural members

Treesearch

Russell C. Moody; Jen Y. Liu

1999-01-01

Glued structural members are manufactured in a variety of configurations. Structural composite lumber (SCL) products consist of small pieces of wood glued together into sizes common for solid-sawn lumber. Glued-laminated timber (glulam) is an engineered stress-rated product that consists of two or more layers of lumber in which the grain of all layers is oriented...

Polarimetry of Pinctada fucata nacre indicates myostracal layer interrupts nacre structure.

PubMed

Metzler, Rebecca A; Jones, Joshua A; D'Addario, Anthony J; Galvez, Enrique J

2017-02-01

The inner layer of many bivalve and gastropod molluscs consists of iridescent nacre, a material that is structured like a brick wall with bricks consisting of crystalline aragonite and mortar of organic molecules. Myostracal layers formed during shell growth at the point of muscle attachment to the shell can be found interspersed within the nacre structure. Little has been done to examine the effect the myostracal layer has on subsequent nacre structure. Here we present data on the structure of the myostracal and nacre layers from a bivalve mollusc, Pinctada fucata . Scanning electron microscope imaging shows the myostracal layer consists of regular crystalline blocks. The nacre before the layer consists of tablets approximately 400 nm thick, while after the myostracal layer the tablets are approximately 500 nm thick. A new technique, imaging polarimetry, indicates that the aragonite crystals within the nacre following the myostracal layer have greater orientation uniformity than before the myostracal layer. The results presented here suggest a possible interaction between the myostracal layer and subsequent shell growth.

Polarimetry of Pinctada fucata nacre indicates myostracal layer interrupts nacre structure

NASA Astrophysics Data System (ADS)

Metzler, Rebecca A.; Jones, Joshua A.; D'Addario, Anthony J.; Galvez, Enrique J.

2017-02-01

The inner layer of many bivalve and gastropod molluscs consists of iridescent nacre, a material that is structured like a brick wall with bricks consisting of crystalline aragonite and mortar of organic molecules. Myostracal layers formed during shell growth at the point of muscle attachment to the shell can be found interspersed within the nacre structure. Little has been done to examine the effect the myostracal layer has on subsequent nacre structure. Here we present data on the structure of the myostracal and nacre layers from a bivalve mollusc, Pinctada fucata. Scanning electron microscope imaging shows the myostracal layer consists of regular crystalline blocks. The nacre before the layer consists of tablets approximately 400 nm thick, while after the myostracal layer the tablets are approximately 500 nm thick. A new technique, imaging polarimetry, indicates that the aragonite crystals within the nacre following the myostracal layer have greater orientation uniformity than before the myostracal layer. The results presented here suggest a possible interaction between the myostracal layer and subsequent shell growth.

Structural covariance networks across healthy young adults and their consistency.

PubMed

Guo, Xiaojuan; Wang, Yan; Guo, Taomei; Chen, Kewei; Zhang, Jiacai; Li, Ke; Jin, Zhen; Yao, Li

2015-08-01

To investigate structural covariance networks (SCNs) as measured by regional gray matter volumes with structural magnetic resonance imaging (MRI) from healthy young adults, and to examine their consistency and stability. Two independent cohorts were included in this study: Group 1 (82 healthy subjects aged 18-28 years) and Group 2 (109 healthy subjects aged 20-28 years). Structural MRI data were acquired at 3.0T and 1.5T using a magnetization prepared rapid-acquisition gradient echo sequence for these two groups, respectively. We applied independent component analysis (ICA) to construct SCNs and further applied the spatial overlap ratio and correlation coefficient to evaluate the spatial consistency of the SCNs between these two datasets. Seven and six independent components were identified for Group 1 and Group 2, respectively. Moreover, six SCNs including the posterior default mode network, the visual and auditory networks consistently existed across the two datasets. The overlap ratios and correlation coefficients of the visual network reached the maximums of 72% and 0.71. This study demonstrates the existence of consistent SCNs corresponding to general functional networks. These structural covariance findings may provide insight into the underlying organizational principles of brain anatomy. © 2014 Wiley Periodicals, Inc.

Structural modifications of graphyne layers consisting of carbon atoms in the sp- and sp{sup 2}-hybridized states

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

Belenkov, E. A., E-mail: belenkov@csu.ru; Mavrinskii, V. V.; Belenkova, T. E.

2015-05-15

A model scheme is proposed for obtaining layered compounds consisting of carbon atoms in the sp- and (vnsp){sup 2}-hybridized states. This model is used to find the possibility of existing the following seven basic structural modifications of graphyne: α-, β1-, β2-, β3-, γ1-, γ2-, and γ3-graphyne. Polymorphic modifications β3 graphyne and γ3 graphyne are described. The basic structural modifications of graphyne contain diatomic polyyne chains and consist only of carbon atoms in two different crystallographically equivalent states. Other nonbasic structural modifications of graphyne can be formed via the elongation of the carbyne chains that connect three-coordinated carbon atoms and viamore » the formation of graphyne layers with a mixed structure consisting of basic layer fragments, such as α-β-graphyne, α-γ-graphyne, and β-γ-graphyne. The semiempirical quantum-mechanical MNDO, AM1, and PM3 methods and ab initio STO6-31G basis calculations are used to find geometrically optimized structures of the basic graphyne layers, their structural parameters, and energies of their sublimation. The energy of sublimation is found to be maximal for γ2-graphyne, which should be the most stable structural modification of graphyne.« less

Dispersion Characteristics of a Helix Loaded Waveguide.

DTIC Science & Technology

1985-09-01

be employed to increase the bandwidth of gyroton amplifiers. The structure consists of helical wires contained concentrially 6. in a cylindrical...bandwidth of gyroton amplifiers. The structure consists of helical wires contained concentrially in a cylindrical conductor. The helical wires are close

Integrative Structure Determination of Protein Assemblies by Satisfaction of Spatial Restraints

NASA Astrophysics Data System (ADS)

Alber, Frank; Chait, Brian T.; Rout, Michael P.; Sali, Andrej

To understand the cell, we need to determine the structures of macromolecular assemblies, many of which consist of tens to hundreds of components. A great variety of experimental data can be used to characterize the assemblies at several levels of resolution, from atomic structures to component configurations. To maximize completeness, resolution, accuracy, precision and efficiency of the structure determination, a computational approach is needed that can use spatial information from a variety of experimental methods. We propose such an approach, defined by its three main components: a hierarchical representation of the assembly, a scoring function consisting of spatial restraints derived from experimental data, and an optimization method that generates structures consistent with the data. We illustrate the approach by determining the configuration of the 456 proteins in the nuclear pore complex from Baker's yeast.

Polarimetry of Pinctada fucata nacre indicates myostracal layer interrupts nacre structure

PubMed Central

Jones, Joshua A.; D'Addario, Anthony J.; Galvez, Enrique J.

2017-01-01

The inner layer of many bivalve and gastropod molluscs consists of iridescent nacre, a material that is structured like a brick wall with bricks consisting of crystalline aragonite and mortar of organic molecules. Myostracal layers formed during shell growth at the point of muscle attachment to the shell can be found interspersed within the nacre structure. Little has been done to examine the effect the myostracal layer has on subsequent nacre structure. Here we present data on the structure of the myostracal and nacre layers from a bivalve mollusc, Pinctada fucata. Scanning electron microscope imaging shows the myostracal layer consists of regular crystalline blocks. The nacre before the layer consists of tablets approximately 400 nm thick, while after the myostracal layer the tablets are approximately 500 nm thick. A new technique, imaging polarimetry, indicates that the aragonite crystals within the nacre following the myostracal layer have greater orientation uniformity than before the myostracal layer. The results presented here suggest a possible interaction between the myostracal layer and subsequent shell growth. PMID:28386442

Below the Surface: Analogical Similarity and Retrieval Competition in Reminding.

ERIC Educational Resources Information Center

Wharton, Charles M.; And Others

1994-01-01

Three experiments involving 222 undergraduates investigated whether and when human memory retrieval is influenced by structural consistency. In all experiments, retrieval competition was manipulated. Results indicate that both retrieval competition and structural consistency influence reminding. Implications for psychological and artificial…

Structure of the N-terminal fragment of Escherichia coli Lon protease

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

Li, Mi; Basic Research Program, SAIC-Frederick, Frederick, MD 21702; Gustchina, Alla

2010-08-01

The medium-resolution structure of the N-terminal fragment of E. coli Lon protease shows that this part of the enzyme consists of two compact domains and a very long α-helix. The structure of a recombinant construct consisting of residues 1–245 of Escherichia coli Lon protease, the prototypical member of the A-type Lon family, is reported. This construct encompasses all or most of the N-terminal domain of the enzyme. The structure was solved by SeMet SAD to 2.6 Å resolution utilizing trigonal crystals that contained one molecule in the asymmetric unit. The molecule consists of two compact subdomains and a very longmore » C-terminal α-helix. The structure of the first subdomain (residues 1–117), which consists mostly of β-strands, is similar to that of the shorter fragment previously expressed and crystallized, whereas the second subdomain is almost entirely helical. The fold and spatial relationship of the two subdomains, with the exception of the C-terminal helix, closely resemble the structure of BPP1347, a 203-amino-acid protein of unknown function from Bordetella parapertussis, and more distantly several other proteins. It was not possible to refine the structure to satisfactory convergence; however, since almost all of the Se atoms could be located on the basis of their anomalous scattering the correctness of the overall structure is not in question. The structure reported here was also compared with the structures of the putative substrate-binding domains of several proteins, showing topological similarities that should help in defining the binding sites used by Lon substrates.« less

78 FR 13097 - Electric Power Research Institute; Seismic Evaluation Guidance

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-26

... outcrop motion for which the soil layers above the foundation elevation have been removed. Updating the... performing soil-structure interaction analyses. Consistent with guidance described in DC/COL-ISG-017, ``Ensuring Hazard-Consistent Seismic Input for Site Response and Soil Structure Interaction Analyses,'' the...

LaCu6-xAgx : A promising host of an elastic quantum critical point

NASA Astrophysics Data System (ADS)

Poudel, L.; Cruz, C. de la; Koehler, M. R.; McGuire, M. A.; Keppens, V.; Mandrus, D.; Christianson, A. D.

2018-05-01

Structural properties of LaCu6-xAgx have been investigated using neutron and x-ray diffraction, and resonant ultrasound spectroscopy (RUS) measurements. Diffraction measurements indicate a continuous structural transition from orthorhombic (Pnma) to monoclinic (P21 / c) structure. RUS measurements show softening of natural frequencies at the structural transition, consistent with the elastic nature of the structural ground state. The structural transition temperatures in LaCu6-xAgx decrease with Ag composition until the monoclinic phase is completely suppressed at xc = 0.225 . All of the evidence is consistent with the presence of an elastic quantum critical point in LaCu6-xAgx .

LaCu 6-xAg x: A promising host of an elastic quantum critical point

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

Poudel, Lekh; Dela Cruz, Clarina R.; Koehler, Michael R.

Structural properties of LaCu 6-xAg x have been investigated using neutron and x-ray diffraction, and resonant ultrasound spectroscopy (RUS) measurements. Diffraction measurements indicate a continuous structural transition from orthorhombic (Pnma) to monoclinic (P2₁/C) structure. RUS measurements show softening of natural frequencies at the structural transition, consistent with the elastic nature of the structural ground state. The structural transition temperatures in LaCu 6-xAg x decrease with Ag composition until the monoclinic phase is completely suppressed at x c=0.225. All of the evidence is consistent with the presence of an elastic quantum critical point in LaCu 6-xAg x.

Neutron reflecting supermirror structure

DOEpatents

Wood, James L.

1992-01-01

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

Are carnivore digestive separation mechanisms revealed on structure-rich diets?: Faecal inconsistency in dogs (Canis familiaris) fed day old chicks

PubMed Central

Clauss, Marcus; Hesta, Myriam; Cools, An; Bosch, Guido; Hendriks, Wouter H.; Janssens, Geert P. J.

2018-01-01

Pronounced variations in faecal consistency have been described anecdotally for some carnivore species fed a structure-rich diet. Typically two faecal consistencies are distinguished, namely hard and firm versus liquid and viscous faeces. It is possible that a separation mechanism is operating in the carnivore digestive tract, as in many herbivore species. Six beagle dogs were fed two experimental diets in a cross-over design of 7 days. Test diets consisted of chunked day old chicks differing only in particle size (fine = 7.8 mm vs coarse = 13 mm) in order to vary dietary structure. Digestive retention time was measured using titanium oxide (TiO2) as marker. The total faecal output was scored for consistency and faecal fermentation profiles were evaluated through faecal short-chain fatty acid (SCFA) and ammonia (NH3) analyses. A total of 181 faecal samples were collected. Dietary particle size did not affect faecal consistency, fermentative end products nor mean retention time (MRT). However, a faecal consistency dichotomy was observed with firm faeces (score 2–2.5) and soft faeces (score 4–4.5) being the most frequently occurring consistencies in an almost alternating pattern in every single dog. Firm and soft faeces differed distinctively in fermentative profiles. Although the structure difference between diets did not affect the faecal dichotomy, feeding whole prey provoked the occurrence of the latter which raises suspicion of a digestive separation mechanism in the canine digestive tract. Further faecal characterisation is however required in order to unravel the underlying mechanism. PMID:29432482

Factor Structure Consistency in the Bruininks-Oseretsky Test--Short Form.

ERIC Educational Resources Information Center

Broadhead, Geoffrey D.; Bruininks, Robert H.

1983-01-01

The underlying structure of the motor abilities represented by the "Short Form of the Bruininks-Oseretsky Test of Motor Proficiency," along with the consistency of the emerging factors by sex and two chronological age (CA) levels, were studied with 765 nondisabled children 4.6 to 14.6 years old. (Author/SEW)

Simulation Computation of 430 Ferritic Stainless Steel Solidification

NASA Astrophysics Data System (ADS)

Pang, Ruipeng; Li, Changrong; Wang, Fuming; Hu, Lifu

The solidification structure of 430 ferritic stainless steel has been calculated in the solidification process by using 3D-CAFE model under the condition of water cooling. The calculated results consistent with those obtained from experiment. Under watercooling condition, the solidification structure consists of chilled layer, columnar grain zone, transition zone and equiaxed grain zone.

15 CFR 738.2 - Commerce Control List (CCL) structure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Export Control Classification Number (ECCN). Each number consists of a set of digits and a letter. The...” ECCN. The last two characters of each “600 series” ECCN generally track the Wassenaar Arrangement... consistent with the structure of the CCL. (2) Reading an ECCN. An ECCN is made up of four sections, the...

How to squeeze a sponge: casein micelles under osmotic stress, a SAXS study.

PubMed

Bouchoux, Antoine; Gésan-Guiziou, Geneviève; Pérez, Javier; Cabane, Bernard

2010-12-01

By combining the osmotic stress technique with small-angle x-ray scattering measurements, we followed the structural response of the casein micelle to an overall increase in concentration. When the aqueous phase that separates the micelles is extracted, they behave as polydisperse repelling spheres and their internal structure is not affected. When they are compressed, the micelles lose water and shrink to a smaller volume. Our results indicate that this compression is nonaffine, i.e., some parts of the micelle collapse, whereas other parts resist deformation. We suggest that this behavior is consistent with a spongelike casein micelle having a triple hierarchical structure. The lowest level of the structure consists of the CaP nanoclusters that serve as anchors for the casein molecules. The intermediate level consists of 10- to 40-nm hard regions that resist compression and contain the nanoclusters. Those regions are connected and/or partially merged with each other, thus forming a continuous and porous material. The third level of structure is the casein micelle itself, with an average size of 100 nm. In our view, such a structure is consistent with the observation of 10- to 20-nm casein particles in the Golgi vesicles of lactating cells: upon aggregation, those particles would rearrange, fuse, and/or swell to form the spongelike micelle. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

How to Squeeze a Sponge: Casein Micelles under Osmotic Stress, a SAXS Study

PubMed Central

Bouchoux, Antoine; Gésan-Guiziou, Geneviève; Pérez, Javier; Cabane, Bernard

2010-01-01

By combining the osmotic stress technique with small-angle x-ray scattering measurements, we followed the structural response of the casein micelle to an overall increase in concentration. When the aqueous phase that separates the micelles is extracted, they behave as polydisperse repelling spheres and their internal structure is not affected. When they are compressed, the micelles lose water and shrink to a smaller volume. Our results indicate that this compression is nonaffine, i.e., some parts of the micelle collapse, whereas other parts resist deformation. We suggest that this behavior is consistent with a spongelike casein micelle having a triple hierarchical structure. The lowest level of the structure consists of the CaP nanoclusters that serve as anchors for the casein molecules. The intermediate level consists of 10- to 40-nm hard regions that resist compression and contain the nanoclusters. Those regions are connected and/or partially merged with each other, thus forming a continuous and porous material. The third level of structure is the casein micelle itself, with an average size of 100 nm. In our view, such a structure is consistent with the observation of 10- to 20-nm casein particles in the Golgi vesicles of lactating cells: upon aggregation, those particles would rearrange, fuse, and/or swell to form the spongelike micelle. PMID:21112300

A review and evaluation of the internal structure and consistency of the Approaches to Teaching Inventory

NASA Astrophysics Data System (ADS)

Harshman, Jordan; Stains, Marilyne

2017-05-01

This study presents a review from 39 studies that provide evidence for the structural validity and internal consistency of the Approaches to Teaching Inventory (ATI). In addition to this review, we evaluate many alternative factor structures on a sample of 267 first- and second-year chemistry faculty members participating in a professional development, a sample of instructors for which the ATI was originally designed. A total of 26 unique factor structures were evaluated. Through robust checking of assumptions, compilations of existing evidence, and new exploratory and confirmatory analyses, we found that there is greater evidence for the structural validity and internal consistency for the 22-item ATI than the 16-item ATI. Additionally, evidence supporting the original two-factor and four-factor structures proposed by the ATI authors (focusing on information transmission and conceptual change) were not reproducible and while alternative models were empirically viable, more theoretical justification is warranted. Recommendations for ATI use and general comments regarding best practices of reporting psychometrics in educational research contexts are discussed.

Implicit transfer of reversed temporal structure in visuomotor sequence learning.

PubMed

Tanaka, Kanji; Watanabe, Katsumi

2014-04-01

Some spatio-temporal structures are easier to transfer implicitly in sequential learning. In this study, we investigated whether the consistent reversal of triads of learned components would support the implicit transfer of their temporal structure in visuomotor sequence learning. A triad comprised three sequential button presses ([1][2][3]) and seven consecutive triads comprised a sequence. Participants learned sequences by trial and error, until they could complete it 20 times without error. Then, they learned another sequence, in which each triad was reversed ([3][2][1]), partially reversed ([2][1][3]), or switched so as not to overlap with the other conditions ([2][3][1] or [3][1][2]). Even when the participants did not notice the alternation rule, the consistent reversal of the temporal structure of each triad led to better implicit transfer; this was confirmed in a subsequent experiment. These results suggest that the implicit transfer of the temporal structure of a learned sequence can be influenced by both the structure and consistency of the change. Copyright © 2013 Cognitive Science Society, Inc.

Fault-tolerant control of large space structures using the stable factorization approach

NASA Technical Reports Server (NTRS)

Razavi, H. C.; Mehra, R. K.; Vidyasagar, M.

1986-01-01

Large space structures are characterized by the following features: they are in general infinite-dimensional systems, and have large numbers of undamped or lightly damped poles. Any attempt to apply linear control theory to large space structures must therefore take into account these features. Phase I consisted of an attempt to apply the recently developed Stable Factorization (SF) design philosophy to problems of large space structures, with particular attention to the aspects of robustness and fault tolerance. The final report on the Phase I effort consists of four sections, each devoted to one task. The first three sections report theoretical results, while the last consists of a design example. Significant results were obtained in all four tasks of the project. More specifically, an innovative approach to order reduction was obtained, stabilizing controller structures for plants with an infinite number of unstable poles were determined under some conditions, conditions for simultaneous stabilizability of an infinite number of plants were explored, and a fault tolerance controller design that stabilizes a flexible structure model was obtained which is robust against one failure condition.

An estimating equation approach to dimension reduction for longitudinal data

PubMed Central

Xu, Kelin; Guo, Wensheng; Xiong, Momiao; Zhu, Liping; Jin, Li

2016-01-01

Sufficient dimension reduction has been extensively explored in the context of independent and identically distributed data. In this article we generalize sufficient dimension reduction to longitudinal data and propose an estimating equation approach to estimating the central mean subspace. The proposed method accounts for the covariance structure within each subject and improves estimation efficiency when the covariance structure is correctly specified. Even if the covariance structure is misspecified, our estimator remains consistent. In addition, our method relaxes distributional assumptions on the covariates and is doubly robust. To determine the structural dimension of the central mean subspace, we propose a Bayesian-type information criterion. We show that the estimated structural dimension is consistent and that the estimated basis directions are root-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$n$\\end{document} consistent, asymptotically normal and locally efficient. Simulations and an analysis of the Framingham Heart Study data confirm the effectiveness of our approach. PMID:27017956

Lumbopelvic muscle activation patterns in three stances under graded loading conditions: Proposing a tensegrity model for load transfer through the sacroiliac joints.

PubMed

Pardehshenas, Hamed; Maroufi, Nader; Sanjari, Mohammad Ali; Parnianpour, Mohamad; Levin, Stephen M

2014-10-01

According to the conventional arch model of the pelvis, stability of the sacroiliac joints may require a predominance of form and force closure mechanisms: the greater the vertical shear force at the sacroiliac joints, the greater the reliance on self-bracing by horizontally or obliquely oriented muscles (such as the internal oblique). But what happens to the arch model when a person stands on one leg? In such cases, the pelvis no longer has imposts, leaving both the arch, and the arch model theory, without support. Do lumbopelvic muscle activation patterns in one-legged stances under load suggest compatibility with a different model? This study compares lumbopelvic muscle activation patterns in two-legged and one-legged stances in response to four levels of graded trunk loading in order to further our understanding the stabilization of the sacroiliac joints. Thirty male subjects experienced four levels of trunk loading (0%, 5%, 10% and 15% of body weight) by holding a bucket at one side, at three conditions: 1) two-legged standing with the bucket in the dominant hand, 2) ipsilateral loading: one-legged standing with the bucket in the dominant hand while using the same-side leg, and 3) contralateral loading: one-legged standing using the same leg used in condition 2, but with the bucket in the non-dominant hand. During these tasks, EMG signals from eight lumbopelvic muscles were collected. ANOVA with repeated design was performed on normalized EMG's to test the main effect of load and condition, and interaction effects of load by condition. Latissimus dorsi and erector spinae muscles showed an antagonistic pattern of activity toward the direction of load which may suggest these muscles as lateral trunk stabilizers. Internal oblique muscles showed a co-activation pattern with increasing task demand, which may function to increase lumbopelvic stability (P < 0.05). No unilateral pattern of the internal obliques was observed during all trials. Our results suggest that the lumbopelvic region uses a similar strategy for load transfer in both double and single leg support positions which is not compatible with the arch analogy. Our findings are more consistent with a suspensory system (wire-spoke wheel model). If our proposed model holds true, the pelvic ring can only be integrated by adjusting tension in the spokes and by preserving rim integrity or continuity. Thus, we propose that in order to restore tension integrity throughout the pelvic ring, efforts to unlock restrictions, muscular correction of positional faults and lumbopelvic or even respiratory exercises following sacroiliac joint dysfunctions must be taken into consideration. Our hypothetical model may initiate thinking and act as a guide to future work based on a biomechanical approach to the problem of sacroiliac joint dysfunction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structural Neural Substrates of Reading the Mind in the Eyes.

PubMed

Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Sawada, Reiko; Kubota, Yasutaka; Yoshimura, Sayaka; Toichi, Motomi

2016-01-01

The ability to read the minds of others in their eyes plays an important role in human adaptation to social environments. Behavioral studies have resulted in the development of a test to measure this ability (Reading the Mind in the Eyes Test, revised version; Eyes Test), and have demonstrated that this ability is consistent over time. Although functional neuroimaging studies revealed brain activation while performing the Eyes Test, the structural neural substrates supporting consistent performance on the Eyes Test remain unclear. In this study, we assessed the Eyes Test and analyzed structural magnetic resonance images using voxel-based morphometry (VBM) in healthy participants. Test performance was positively associated with the gray matter volumes of the dorsomedial prefrontal cortex, inferior parietal lobule (temporoparietal junction), and precuneus in the left hemisphere. These results suggest that the fronto-temporoparietal network structures support the consistent ability to read the mind in the eyes.

Electronic structure and magneto-optical effects in CeSb

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

Liechtenstein, A.I.; Antropov, V.P.; Harmon, B.N.

1994-04-15

The electronic structure and magneto-optical spectra of CeSb have been calculated using the self-consistent local-density approximation with explicit on-site Coulomb parameters for the correlated [ital f] state of cerium. The essential electronic structure of cerium antimonide consists of one occupied [ital f] band, predominantly with orbital [ital m]=[minus]3 character and spin [sigma]=1 located 2 eV below the Fermi level and interacting with broad Sb [ital p] bands crossing [ital E][sub [ital F

Pre-Service Science Teachers' Cognitive Structures Regarding Science, Technology, Engineering, Mathematics (STEM) and Science Education

ERIC Educational Resources Information Center

Hacioglu, Yasemin; Yamak, Havva; Kavak, Nusret

2016-01-01

The aim of this study is to reveal pre-service science teachers' cognitive structures regarding Science, Technology, Engineering, Mathematics (STEM) and science education. The study group of the study consisted of 192 pre-service science teachers. A Free Word Association Test (WAT) consisting of science, technology, engineering, mathematics and…

Structure of the N-terminal fragment of Escherichia coli Lon protease

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

Li, Mi; Gustchina, Alla; Rasulova, Fatima S.

2010-10-22

The structure of a recombinant construct consisting of residues 1-245 of Escherichia coli Lon protease, the prototypical member of the A-type Lon family, is reported. This construct encompasses all or most of the N-terminal domain of the enzyme. The structure was solved by SeMet SAD to 2.6 {angstrom} resolution utilizing trigonal crystals that contained one molecule in the asymmetric unit. The molecule consists of two compact subdomains and a very long C-terminal {alpha}-helix. The structure of the first subdomain (residues 1-117), which consists mostly of {beta}-strands, is similar to that of the shorter fragment previously expressed and crystallized, whereas themore » second subdomain is almost entirely helical. The fold and spatial relationship of the two subdomains, with the exception of the C-terminal helix, closely resemble the structure of BPP1347, a 203-amino-acid protein of unknown function from Bordetella parapertussis, and more distantly several other proteins. It was not possible to refine the structure to satisfactory convergence; however, since almost all of the Se atoms could be located on the basis of their anomalous scattering the correctness of the overall structure is not in question. The structure reported here was also compared with the structures of the putative substrate-binding domains of several proteins, showing topological similarities that should help in defining the binding sites used by Lon substrates.« less

Design, Analysis and Fabrication of Secondary Structural Components for the Habitat Demonstration Unit-Deep Space Habitat

NASA Technical Reports Server (NTRS)

Smith, Russell W.; Langford, William M.

2012-01-01

In support of NASA s Habitat Demonstration Unit - Deep Space Habitat Prototype, a number of evolved structural sections were designed, fabricated, analyzed and installed in the 5 meter diameter prototype. The hardware consisted of three principal structural sections, and included the development of novel fastener insert concepts. The articles developed consisted of: 1) 1/8th of the primary flooring section, 2) an inner radius floor beam support which interfaced with, and supported (1), 3) two upper hatch section prototypes, and 4) novel insert designs for mechanical fastener attachments. Advanced manufacturing approaches were utilized in the fabrication of the components. The structural components were developed using current commercial aircraft constructions as a baseline (for both the flooring components and their associated mechanical fastener inserts). The structural sections utilized honeycomb sandwich panels. The core section consisted of 1/8th inch cell size Nomex, at 9 lbs/cu ft, and which was 0.66 inches thick. The facesheets had 3 plys each, with a thickness of 0.010 inches per ply, made from woven E-glass with epoxy reinforcement. Analysis activities consisted of both analytical models, as well as initial closed form calculations. Testing was conducted to help verify analysis model inputs, as well as to facilitate correlation between testing and analysis. Test activities consisted of both 4 point bending tests as well as compressive core crush sequences. This paper presents an overview of this activity, and discusses issues encountered during the various phases of the applied research effort, and its relevance to future space based habitats.

Structural differences in the bacterial flagellar motor among bacterial species.

PubMed

Terashima, Hiroyuki; Kawamoto, Akihiro; Morimoto, Yusuke V; Imada, Katsumi; Minamino, Tohru

2017-01-01

The bacterial flagellum is a supramolecular motility machine consisting of the basal body as a rotary motor, the hook as a universal joint, and the filament as a helical propeller. Intact structures of the bacterial flagella have been observed for different bacterial species by electron cryotomography and subtomogram averaging. The core structures of the basal body consisting of the C ring, the MS ring, the rod and the protein export apparatus, and their organization are well conserved, but novel and divergent structures have also been visualized to surround the conserved structure of the basal body. This suggests that the flagellar motors have adapted to function in various environments where bacteria live and survive. In this review, we will summarize our current findings on the divergent structures of the bacterial flagellar motor.

Stage Structure of Moral Development: A Comparison of Alternative Models.

ERIC Educational Resources Information Center

Hau, Kit-Tai

This study evaluated the stage structure of several quasi-simplex and non-simplex models of moral development in two domains of moral development in a British and a Chinese sample. Analyses were based on data reported by Sachs (1992): the Chinese sample consisted of 1,005 students from grade 9 to post-college, and the British sample consisted of…

Structural stability as a consistent predictor of phenological events.

PubMed

Song, Chuliang; Saavedra, Serguei

2018-06-13

The timing of the first and last seasonal appearance of a species in a community typically follows a pattern that is governed by temporal factors. While it has been shown that changes in the environment are linked to phenological changes, the direction of this link appears elusive and context-dependent. Thus, finding consistent predictors of phenological events is of central importance for a better assessment of expected changes in the temporal dynamics of ecological communities. Here we introduce a measure of structural stability derived from species interaction networks as an estimator of the expected range of environmental conditions compatible with the existence of a community. We test this measure as a predictor of changes in species richness recorded on a daily basis in a high-arctic plant-pollinator community during two spring seasons. We find that our measure of structural stability is the only consistent predictor of changes in species richness among different ecological and environmental variables. Our findings suggest that measures based on the notion of structural stability can synthesize the expected variation of environmental conditions tolerated by a community, and explain more consistently the phenological changes observed in ecological communities. © 2018 The Author(s).

Individual Functional ROI Optimization via Maximization of Group-wise Consistency of Structural and Functional Profiles

PubMed Central

Li, Kaiming; Guo, Lei; Zhu, Dajiang; Hu, Xintao; Han, Junwei; Liu, Tianming

2013-01-01

Studying connectivities among functional brain regions and the functional dynamics on brain networks has drawn increasing interest. A fundamental issue that affects functional connectivity and dynamics studies is how to determine the best possible functional brain regions or ROIs (regions of interest) for a group of individuals, since the connectivity measurements are heavily dependent on ROI locations. Essentially, identification of accurate, reliable and consistent corresponding ROIs is challenging due to the unclear boundaries between brain regions, variability across individuals, and nonlinearity of the ROIs. In response to these challenges, this paper presents a novel methodology to computationally optimize ROIs locations derived from task-based fMRI data for individuals so that the optimized ROIs are more consistent, reproducible and predictable across brains. Our computational strategy is to formulate the individual ROI location optimization as a group variance minimization problem, in which group-wise consistencies in functional/structural connectivity patterns and anatomic profiles are defined as optimization constraints. Our experimental results from multimodal fMRI and DTI data show that the optimized ROIs have significantly improved consistency in structural and functional profiles across individuals. These improved functional ROIs with better consistency could contribute to further study of functional interaction and dynamics in the human brain. PMID:22281931

Structural, electronic and vibrational properties of lanthanide monophosphide at high pressure

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

Panchal, J. M., E-mail: amitjignesh@yahoo.co.in; Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat; Joshi, Mitesh

2016-05-06

A first-principles plane wave self-consistent method with the ultra-soft-pseudopotential scheme in the framework of the density functional theory (DFT) is performed to study structural, electronic and vibrational properties of LaP for Rock-salt (NaCl/Bl) and Cesium-chloride (CsCl/B2) phases. The instability of Rock-salt (NaCl/Bl) phases around the transition is discussed. Conclusions based on electronic energy band structure, density of state, phonon dispersion and phonon density of states in both phases are outlined. The calculated results are consistence and confirm the successful applicability of quasi-harmonic phonon theory for structural instability studies for the alloys.

Evidence of a Love wave bandgap in a quartz substrate coated with a phononic thin layer

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

Liu, Ting-Wei; Wu, Tsung-Tsong, E-mail: wutt@ntu.edu.tw; Lin, Yu-Ching

This paper presents a numerical and experimental study of Love wave propagation in a micro-fabricated phononic crystal (PC) structure consisting of a 2D, periodically etched silica film deposited on a quartz substrate. The dispersion characteristics of Love waves in such a phononic structure were analyzed with various geometric parameters by using complex band structure calculations. For the experiment, we adopted reactive-ion etching with electron-beam lithography to fabricate a submicrometer phononic structure. The measured results exhibited consistency with the numerical prediction. The results of this study may serve as a basis for developing PC-based Love wave devices.

PREFMD: a web server for protein structure refinement via molecular dynamics simulations.

PubMed

Heo, Lim; Feig, Michael

2018-03-15

Refinement of protein structure models is a long-standing problem in structural bioinformatics. Molecular dynamics-based methods have emerged as an avenue to achieve consistent refinement. The PREFMD web server implements an optimized protocol based on the method successfully tested in CASP11. Validation with recent CASP refinement targets shows consistent and more significant improvement in global structure accuracy over other state-of-the-art servers. PREFMD is freely available as a web server at http://feiglab.org/prefmd. Scripts for running PREFMD as a stand-alone package are available at https://github.com/feiglab/prefmd.git. feig@msu.edu. Supplementary data are available at Bioinformatics online.

Clustering and visualizing similarity networks of membrane proteins.

PubMed

Hu, Geng-Ming; Mai, Te-Lun; Chen, Chi-Ming

2015-08-01

We proposed a fast and unsupervised clustering method, minimum span clustering (MSC), for analyzing the sequence-structure-function relationship of biological networks, and demonstrated its validity in clustering the sequence/structure similarity networks (SSN) of 682 membrane protein (MP) chains. The MSC clustering of MPs based on their sequence information was found to be consistent with their tertiary structures and functions. For the largest seven clusters predicted by MSC, the consistency in chain function within the same cluster is found to be 100%. From analyzing the edge distribution of SSN for MPs, we found a characteristic threshold distance for the boundary between clusters, over which SSN of MPs could be properly clustered by an unsupervised sparsification of the network distance matrix. The clustering results of MPs from both MSC and the unsupervised sparsification methods are consistent with each other, and have high intracluster similarity and low intercluster similarity in sequence, structure, and function. Our study showed a strong sequence-structure-function relationship of MPs. We discussed evidence of convergent evolution of MPs and suggested applications in finding structural similarities and predicting biological functions of MP chains based on their sequence information. © 2015 Wiley Periodicals, Inc.

Measuring the learning capacity of organisations: development and factor analysis of the Questionnaire for Learning Organizations.

PubMed

Oudejans, S C C; Schippers, G M; Schramade, M H; Koeter, M W J; van den Brink, W

2011-04-01

To investigate internal consistency and factor structure of a questionnaire measuring learning capacity based on Senge's theory of the five disciplines of a learning organisation: Personal Mastery, Mental Models, Shared Vision, Team Learning, and Systems Thinking. Cross-sectional study. Substance-abuse treatment centres (SATCs) in The Netherlands. A total of 293 SATC employees from outpatient and inpatient treatment departments, financial and human resources departments. Psychometric properties of the Questionnaire for Learning Organizations (QLO), including factor structure, internal consistency, and interscale correlations. A five-factor model representing the five disciplines of Senge showed good fit. The scales for Personal Mastery, Shared Vision and Team Learning had good internal consistency, but the scales for Systems Thinking and Mental Models had low internal consistency. The proposed five-factor structure was confirmed in the QLO, which makes it a promising instrument to assess learning capacity in teams. The Systems Thinking and the Mental Models scales have to be revised. Future research should be aimed at testing criterion and discriminatory validity.

Automated Reconstruction of Historic Roof Structures from Point Clouds - Development and Examples

NASA Astrophysics Data System (ADS)

Pöchtrager, M.; Styhler-Aydın, G.; Döring-Williams, M.; Pfeifer, N.

2017-08-01

The analysis of historic roof constructions is an important task for planning the adaptive reuse of buildings or for maintenance and restoration issues. Current approaches to modeling roof constructions consist of several consecutive operations that need to be done manually or using semi-automatic routines. To increase efficiency and allow the focus to be on analysis rather than on data processing, a set of methods was developed for the fully automated analysis of the roof constructions, including integration of architectural and structural modeling. Terrestrial laser scanning permits high-detail surveying of large-scale structures within a short time. Whereas 3-D laser scan data consist of millions of single points on the object surface, we need a geometric description of structural elements in order to obtain a structural model consisting of beam axis and connections. Preliminary results showed that the developed methods work well for beams in flawless condition with a quadratic cross section and no bending. Deformations or damages such as cracks and cuts on the wooden beams can lead to incomplete representations in the model. Overall, a high degree of automation was achieved.

A Neuro-Oncology Workstation for Structuring, Modeling, and Visualizing Patient Records

PubMed Central

Hsu, William; Arnold, Corey W.; Taira, Ricky K.

2016-01-01

The patient medical record contains a wealth of information consisting of prior observations, interpretations, and interventions that need to be interpreted and applied towards decisions regarding current patient care. Given the time constraints and the large—often extraneous—amount of data available, clinicians are tasked with the challenge of performing a comprehensive review of how a disease progresses in individual patients. To facilitate this process, we demonstrate a neuro-oncology workstation that assists in structuring and visualizing medical data to promote an evidence-based approach for understanding a patient’s record. The workstation consists of three components: 1) a structuring tool that incorporates natural language processing to assist with the extraction of problems, findings, and attributes for structuring observations, events, and inferences stated within medical reports; 2) a data modeling tool that provides a comprehensive and consistent representation of concepts for the disease-specific domain; and 3) a visual workbench for visualizing, navigating, and querying the structured data to enable retrieval of relevant portions of the patient record. We discuss this workstation in the context of reviewing cases of glioblastoma multiforme patients. PMID:27583308

A Neuro-Oncology Workstation for Structuring, Modeling, and Visualizing Patient Records.

PubMed

Hsu, William; Arnold, Corey W; Taira, Ricky K

2010-11-01

The patient medical record contains a wealth of information consisting of prior observations, interpretations, and interventions that need to be interpreted and applied towards decisions regarding current patient care. Given the time constraints and the large-often extraneous-amount of data available, clinicians are tasked with the challenge of performing a comprehensive review of how a disease progresses in individual patients. To facilitate this process, we demonstrate a neuro-oncology workstation that assists in structuring and visualizing medical data to promote an evidence-based approach for understanding a patient's record. The workstation consists of three components: 1) a structuring tool that incorporates natural language processing to assist with the extraction of problems, findings, and attributes for structuring observations, events, and inferences stated within medical reports; 2) a data modeling tool that provides a comprehensive and consistent representation of concepts for the disease-specific domain; and 3) a visual workbench for visualizing, navigating, and querying the structured data to enable retrieval of relevant portions of the patient record. We discuss this workstation in the context of reviewing cases of glioblastoma multiforme patients.

Lagrangian space consistency relation for large scale structure

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

Horn, Bart; Hui, Lam; Xiao, Xiao

Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias & Riotto and Peloso & Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present.more » Furthermore, the simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space.« less

Lagrangian space consistency relation for large scale structure

DOE PAGES

Horn, Bart; Hui, Lam; Xiao, Xiao

2015-09-29

Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias & Riotto and Peloso & Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present.more » Furthermore, the simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space.« less

Coherent diffraction imaging: consistency of the assembled three-dimensional distribution.

PubMed

Tegze, Miklós; Bortel, Gábor

2016-07-01

The short pulses of X-ray free-electron lasers can produce diffraction patterns with structural information before radiation damage destroys the particle. From the recorded diffraction patterns the structure of particles or molecules can be determined on the nano- or even atomic scale. In a coherent diffraction imaging experiment thousands of diffraction patterns of identical particles are recorded and assembled into a three-dimensional distribution which is subsequently used to solve the structure of the particle. It is essential to know, but not always obvious, that the assembled three-dimensional reciprocal-space intensity distribution is really consistent with the measured diffraction patterns. This paper shows that, with the use of correlation maps and a single parameter calculated from them, the consistency of the three-dimensional distribution can be reliably validated.

The inner formal structure of the H-T-P drawings: an exploratory study.

PubMed

Vass, Z

1998-08-01

The study describes some interrelated patterns of traits of the House-Tree-Person (H-T-P) drawings with the instruments of hierarchical cluster analysis. First, according to the literature 1 7 formal or structural aspects of the projective drawings were collected, after which a detailed manual for coding was compiled. Second, the interrater reliability and the consistency of this manual was tested. Third, the hierarchical cluster structure of the reliable and consistent formal aspects was analysed. Results are: (a) a psychometrically tested coding manual of the investigated formal-structural aspects, each of them illustrated with drawings that showed the highest interrater agreement; and (b) the hierarchic cluster structure of the formal aspects of the H-T-P drawings of "normal" adults.

Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

PubMed Central

Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

2010-01-01

We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

In-situ and Ex-situ Observations of Lithium De-intercalation from LiCoO2: Atomic Force Microscopy and Transmission Electron Microscopy Studies

DTIC Science & Technology

2005-06-01

has a layered structure consisting of lithium and cobalt sheets stacked alternatively between oxygen sheets. Li and Co occupy octahedral sites in...cobalt sheets stacked alternatively between ABCABC close-packed oxygen arrays. Li and Co occupy octahedral sites in alternating layers between the oxygen... Co 4.- o 4 Li Figure 1: Crystal structure of LiCoO2. LiCoO2 has a layered structure consisting of lithium and cobalt sheets stacked alternatively

Shear flow of one-component polarizable fluid in a strong electric field

NASA Astrophysics Data System (ADS)

Sun, J. M.; Tao, R.

1996-04-01

A shear flow of one-component polarizable fluid in a strong electric field has a structural transition at a critical shear stress. When the shear stress is increased from zero up to the critical shear stress, the flow (in the x direction) has a flowing-chain (FC) structure, consisting of tilted or broken chains along the field (z direction). At the critical shear stress, the FC structure gives way to a flowing-hexagonal-layered (FHL) structure, consisting of several two-dimensional layers which are parallel to the x-z plane. Within one layer, particles form strings in the flow direction. Strings are constantly sliding over particles in strings right beneath. The effective viscosity drops dramatically at the structural change. As the shear stress reduces, the FHL structure persists even under a stress-free state if the thermal fluctuation is very weak. This structure change in the charging and discharging process produces a large hysteresis.

Preparation and Characterization of Organic-Inorganic Hybrid Macrocyclic Compounds: Cyclic Ladder-like Polyphenylsilsesquioxanes.

PubMed

Zhang, Wenchao; Wang, Xiaoxia; Wu, Yiwei; Qi, Zhi; Yang, Rongjie

2018-04-02

Organic-inorganic hybrid macrocyclic compounds, cyclic polyphenylsilsesquioxanes (cyc-PSQs), have been synthesized through hydrolysis and condensation reactions of phenyltrichlorosilane. Structural characterization has revealed that cyc-PSQs consist of a closed-ring double-chain siloxane inorganic backbone bearing organic phenyl groups. The cyc-PSQ molecules have been simulated and structurally optimized using the Forcite tool as implemented in Materials Studio. Structurally optimized cyc-PSQs are highly symmetrical and regular with high stereoregularity, consistent with the dimensions of their experimentally derived structures. Thermogravimetric analysis showed that these macrocyclic compounds have excellent thermal stability. In addition to these perfectly structured compounds, macrocyclic compounds with the same ring ladder structure but bearing an additional Si-OH group, cyc-PSQs-OH, have also been synthesized. A possible mechanism for the formation of the closed-ring molecular structures of cyc-PSQs and cyc-PSQs-OH is proposed.

ParallelStructure: A R Package to Distribute Parallel Runs of the Population Genetics Program STRUCTURE on Multi-Core Computers

PubMed Central

Besnier, Francois; Glover, Kevin A.

2013-01-01

This software package provides an R-based framework to make use of multi-core computers when running analyses in the population genetics program STRUCTURE. It is especially addressed to those users of STRUCTURE dealing with numerous and repeated data analyses, and who could take advantage of an efficient script to automatically distribute STRUCTURE jobs among multiple processors. It also consists of additional functions to divide analyses among combinations of populations within a single data set without the need to manually produce multiple projects, as it is currently the case in STRUCTURE. The package consists of two main functions: MPI_structure() and parallel_structure() as well as an example data file. We compared the performance in computing time for this example data on two computer architectures and showed that the use of the present functions can result in several-fold improvements in terms of computation time. ParallelStructure is freely available at https://r-forge.r-project.org/projects/parallstructure/. PMID:23923012

Results of Copper-Silver Rail Materials Tests

DTIC Science & Technology

2006-05-01

dislocation-dense grain structure. An annealing, recrystallization , and re-straining model is proposed to predict the bandwidth within which the...darker phase is the copper-rich solid solution, while the lighter regions are the eutectic structure consisting of both copper-rich and silver-rich solid...solutions. The eutectic phase ribbons consist of finer copper and silver filaments [1], [5]. The two phases are inhomogeneously deformed during the

Terahertz Bandpass Frequency Selective Surfaces on Glass Substrates Using a Wet Micromachining Process

NASA Astrophysics Data System (ADS)

Ramzan, Mehrab; Khan, Talha Masood; Bolat, Sami; Nebioglu, Mehmet Ali; Altan, Hakan; Okyay, Ali Kemal; Topalli, Kagan

2017-08-01

This paper presents terahertz (THz) frequency selective surfaces (FSS) implemented on glass substrate using standard microfabrication techniques. These FSS structures are designed for frequencies around 0.8 THz. A fabrication process is proposed where a 100-μm-thick glass substrate is formed through the HF etching of a standard 500-μm-thick low cost glass wafer. Using this fabrication process, three separate robust designs consisting of single-layer FSS are investigated using high-frequency structural simulator (HFSS). Based on the simulation results, the first design consists of a circular ring slot in a square metallic structure on top of a 100-μm-thick Pyrex glass substrate with 70% transmission bandwidth of approximately 0.07 THz, which remains nearly constant till 30° angle of incidence. The second design consists of a tripole structure on top of a 100-μm-thick Pyrex glass substrate with 65% transmission bandwidth of 0.035 THz, which remains nearly constant till 30° angle of incidence. The third structure consists of a triangular ring slot in a square metal on top of a 100-μm-thick Pyrex glass substrate with 70% transmission bandwidth of 0.051 THz, which remains nearly constant up to 20° angle of incidence. These designs show that the reflections from samples can be reduced compared to the conventional sample holders used in THz spectroscopy applications, by using single layer FSS structures manufactured through a relatively simple fabrication process. Practically, these structures are achieved on a fabricated 285-μm-thick glass substrate. Taking into account the losses and discrepancies in the substrate thickness, the measured results are in good agreement with the electromagnetic simulations.

Inbreeding Avoidance Drives Consistent Variation of Fine-Scale Genetic Structure Caused by Dispersal in the Seasonal Mating System of Brandt’s Voles

PubMed Central

Liu, Xiao Hui; Yue, Ling Fen; Wang, Da Wei; Li, Ning; Cong, Lin

2013-01-01

Inbreeding depression is a major evolutionary and ecological force influencing population dynamics and the evolution of inbreeding-avoidance traits such as mating systems and dispersal. Mating systems and dispersal are fundamental determinants of population genetic structure. Resolving the relationships among genetic structure, seasonal breeding-related mating systems and dispersal will facilitate our understanding of the evolution of inbreeding avoidance. The goals of this study were as follows: (i) to determine whether females actively avoided mating with relatives in a group-living rodent species, Brandt’s voles (Lasiopodomys brandtii), by combined analysis of their mating system, dispersal and genetic structure; and (ii) to analyze the relationships among the variation in fine-genetic structure, inbreeding avoidance, season-dependent mating strategies and individual dispersal. Using both individual- and population-level analyses, we found that the majority of Brandt’s vole groups consisted of close relatives. However, both group-specific FISs, an inbreeding coefficient that expresses the expected percentage rate of homozygosity arising from a given breeding system, and relatedness of mates showed no sign of inbreeding. Using group pedigrees and paternity analysis, we show that the mating system of Brandt’s voles consists of a type of polygyny for males and extra-group polyandry for females, which may decrease inbreeding by increasing the frequency of mating among distantly-related individuals. The consistent variation in within-group relatedness, among-group relatedness and fine-scale genetic structures was mostly due to dispersal, which primarily occurred during the breeding season. Biologically relevant variation in the fine-scale genetic structure suggests that dispersal during the mating season may be a strategy to avoid inbreeding and drive the polygynous and extra-group polyandrous mating system of this species. PMID:23516435

Fractal multi-level organisation of human groups in a virtual world.

PubMed

Fuchs, Benedikt; Sornette, Didier; Thurner, Stefan

2014-10-06

Humans are fundamentally social. They form societies which consist of hierarchically layered nested groups of various quality, size, and structure. The anthropologic literature has classified these groups as support cliques, sympathy groups, bands, cognitive groups, tribes, linguistic groups, and so on. Anthropologic data show that, on average, each group consists of approximately three subgroups. However, a general understanding of the structural dependence of groups at different layers is largely missing. We extend these early findings to a very large high-precision large-scale internet-based social network data. We analyse the organisational structure of a complete, multi-relational, large social multiplex network of a human society consisting of about 400,000 odd players of an open-ended massive multiplayer online game for which we know all about their various group memberships at different layers. Remarkably, the online players' society exhibits the same type of structured hierarchical layers as found in hunter-gatherer societies. Our findings suggest that the hierarchical organisation of human society is deeply nested in human psychology.

Reliability of a structured interview for admission to an emergency medicine residency program.

PubMed

Blouin, Danielle

2010-10-01

Interviews are most important in resident selection. Structured interviews are more reliable than unstructured ones. We sought to measure the interrater reliability of a newly designed structured interview during the selection process to an Emergency Medicine residency program. The critical incident technique was used to extract the desired dimensions of performance. The interview tool consisted of 7 clinical scenarios and 1 global rating. Three trained interviewers marked each candidate on all scenarios without discussing candidates' responses. Interitem consistency and estimates of variance were computed. Twenty-eight candidates were interviewed. The generalizability coefficient was 0.67. Removing the central tendency ratings increased the coefficient to 0.74. Coefficients of interitem consistency ranged from 0.64 to 0.74. The structured interview tool provided good although suboptimal interrater reliability. Increasing the number of scenarios improves reliability as does applying differential weights to the rating scale anchors. The latter would also facilitate the identification of those candidates with extreme ratings.

Fractal multi-level organisation of human groups in a virtual world

PubMed Central

Fuchs, Benedikt; Sornette, Didier; Thurner, Stefan

2014-01-01

Humans are fundamentally social. They form societies which consist of hierarchically layered nested groups of various quality, size, and structure. The anthropologic literature has classified these groups as support cliques, sympathy groups, bands, cognitive groups, tribes, linguistic groups, and so on. Anthropologic data show that, on average, each group consists of approximately three subgroups. However, a general understanding of the structural dependence of groups at different layers is largely missing. We extend these early findings to a very large high-precision large-scale internet-based social network data. We analyse the organisational structure of a complete, multi-relational, large social multiplex network of a human society consisting of about 400,000 odd players of an open-ended massive multiplayer online game for which we know all about their various group memberships at different layers. Remarkably, the online players' society exhibits the same type of structured hierarchical layers as found in hunter-gatherer societies. Our findings suggest that the hierarchical organisation of human society is deeply nested in human psychology. PMID:25283998

Fractal multi-level organisation of human groups in a virtual world

NASA Astrophysics Data System (ADS)

Fuchs, Benedikt; Sornette, Didier; Thurner, Stefan

2014-10-01

Humans are fundamentally social. They form societies which consist of hierarchically layered nested groups of various quality, size, and structure. The anthropologic literature has classified these groups as support cliques, sympathy groups, bands, cognitive groups, tribes, linguistic groups, and so on. Anthropologic data show that, on average, each group consists of approximately three subgroups. However, a general understanding of the structural dependence of groups at different layers is largely missing. We extend these early findings to a very large high-precision large-scale internet-based social network data. We analyse the organisational structure of a complete, multi-relational, large social multiplex network of a human society consisting of about 400,000 odd players of an open-ended massive multiplayer online game for which we know all about their various group memberships at different layers. Remarkably, the online players' society exhibits the same type of structured hierarchical layers as found in hunter-gatherer societies. Our findings suggest that the hierarchical organisation of human society is deeply nested in human psychology.

Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

DOE PAGES

Zhang, C. L.; Bhat, G. H.; Nazarewicz, W.; ...

2015-09-10

Here, whether atomic nuclei can possess triaxial shapes at their ground states is still a subject of ongoing debate. According to theory, good prospects for low-spin triaxiality are in the neutron-rich Mo-Ru region. Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. The purpose of this study is to understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-richmore » even-even nuclei around 110Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear density functional theory (DFT) with the optimized energy density functional UNEDF0. We also apply triaxial projected shell model (TPSM) to describe yrast and positive-parity, near-yrast band structures. As a result, our self-consistent DFT calculations predict triaxial ground-state deformations in 106,108Mo and 108,110,112Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-gamma structure, associated with the aligned ν(h 11/2) 2 pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Lastly, the structure of neutron-rich even-even nuclei around Ru-110 is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.« less

Is chronic pain associated with somatization/hypochondriasis? An evidence-based structured review.

PubMed

Fishbain, David A; Lewis, John E; Gao, Jinrun; Cole, Brandly; Steele Rosomoff, R

2009-01-01

This is an evidence-based structured review. The objectives of this review were to answer the following questions: (1) Are somatization/hypochondriasis associated with chronic pain? (2) Is the degree of somatization/hypochondriasis related to pain levels? (3) Does pain treatment improve somatization/hypochondriasis? (4) Are some pain diagnoses differentially associated with somatization/hypochondriasis? Fifty-seven studies which fulfilled inclusion criteria and had high quality scores were sorted by the above-mentioned objectives. Agency for health care policy and research guidelines were utilized to type and characterize the strength/consistency of the study evidence within each objective. Somatization and hypochondriasis were both consistently associated with chronic pain (consistency ratings B and A, respectively). Study evidence indicated a correlation between pain intensity and presence of somatization and hypochondriasis (consistency rating A and B, respectively). Pain treatment improved somatization and hypochondriasis (consistency rating B and A, respectively). Some chronic pain diagnostic groups somatized more (consistency rating B). Somatization is commonly associated with chronic pain and may relate to pain levels.

A novel constant-force scanning probe incorporating mechanical-magnetic coupled structures.

PubMed

Wang, Hongxi; Zhao, Jian; Gao, Renjing; Yang, Yintang

2011-07-01

A one-dimensional scanning probe with constant measuring force is designed and fabricated by utilizing the negative stiffness of the magnetic coupled structure, which mainly consists of the magnetic structure, the parallel guidance mechanism, and the pre-stressed spring. Based on the theory of material mechanics and the equivalent surface current model for computing the magnetic force, the analytical model of the scanning probe subjected to multi-forces is established, and the nonlinear relationship between the measuring force and the probe displacement is obtained. The practicability of introducing magnetic coupled structure in the constant-force probe is validated by the consistency of the results in numerical simulation and experiments.

Convergence of an iterative procedure for large-scale static analysis of structural components

NASA Technical Reports Server (NTRS)

Austin, F.; Ojalvo, I. U.

1976-01-01

The paper proves convergence of an iterative procedure for calculating the deflections of built-up component structures which can be represented as consisting of a dominant, relatively stiff primary structure and a less stiff secondary structure, which may be composed of one or more substructures that are not connected to one another but are all connected to the primary structure. The iteration consists in estimating the deformation of the primary structure in the absence of the secondary structure on the assumption that all mechanical loads are applied directly to the primary structure. The j-th iterate primary structure deflections at the interface are imposed on the secondary structure, and the boundary loads required to produce these deflections are computed. The cycle is completed by applying the interface reaction to the primary structure and computing its updated deflections. It is shown that the mathematical condition for convergence of this procedure is that the maximum eigenvalue of the equation relating primary-structure deflection to imposed secondary-structure deflection be less than unity, which is shown to correspond with the physical requirement that the secondary structure be more flexible at the interface boundary.

Lagrangian space consistency relation for large scale structure

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

Horn, Bart; Hui, Lam; Xiao, Xiao, E-mail: bh2478@columbia.edu, E-mail: lh399@columbia.edu, E-mail: xx2146@columbia.edu

Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias and Riotto and Peloso and Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present.more » The simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space.« less

Psychometric properties of the Brief Symptom Inventory-18 in a Spanish breast cancer sample.

PubMed

Galdón, Ma José; Durá, Estrella; Andreu, Yolanda; Ferrando, Maite; Murgui, Sergio; Pérez, Sandra; Ibañez, Elena

2008-12-01

The objective of this work was to study the psychometric and structural properties of the Brief Symptom Inventory-18 (BSI-18) in a sample of breast cancer patients (N=175). Confirmatory factor analyses were conducted. Two models were tested: the theoretical model with the original structure (three-dimensional), and the empirical model (a four-factor structure) obtained through exploratory factor analysis initially performed by the authors of the BSI-18. The eligible structure was the original proposal consisting of three dimensions: somatization, depression, and anxiety scores. These measures also showed good internal consistency. The results of this study support the reliability and structural validity of the BSI-18 as a standardized instrument for screening purposes in breast cancer patients, with the added benefits of simplicity and ease of application.

An Investigation of Attitude Consistency.

ERIC Educational Resources Information Center

Leonard, Wilbert M., II

The author explores some germane implications of cognitive consistency theory. An "affective-cognitive consistency" theory, which specifies the relationship between the affective and cognitive components of the attitude structure, was taken as the theoretical basis of this study. The theory suggests that by knowing what a person values, it should…

Three-dimensionality of the bulk electronic structure in WTe 2

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

Wu, Yun; Jo, Na Hyun; Mou, Daixiang

Inmore » this paper, we use temperature- and field-dependent resistivity measurements (Shubnikov–de Haas quantum oscillations) and ultrahigh-resolution, tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy (ARPES) to study the three-dimensionality (3D) of the bulk electronic structure in WTe 2 , a type II Weyl semimetal. The bulk Fermi surface (FS) consists of two pairs of electron pockets and two pairs of hole pockets along the Χ–Γ–Χ direction as detected by using an incident photon energy of 6.7 eV, which is consistent with the previously reported data. However, if using an incident photon energy of 6.36 eV, another pair of tiny electron pockets is detected on both sides of the Γ point, which is in agreement with the small quantum oscillation frequency peak observed in the magnetoresistance. Therefore, the bulk, 3D FS consists of three pairs of electron pockets and two pairs of hole pockets in total. With the ability of fine tuning the incident photon energy, we demonstrate the strong three-dimensionality of the bulk electronic structure in WTe 2 . Finally, the combination of resistivity and ARPES measurements reveals the complete, and consistent, picture of the bulk electronic structure of this material.« less

Three-dimensionality of the bulk electronic structure in WTe 2

DOE PAGES

Wu, Yun; Jo, Na Hyun; Mou, Daixiang; ...

2017-05-18

Inmore » this paper, we use temperature- and field-dependent resistivity measurements (Shubnikov–de Haas quantum oscillations) and ultrahigh-resolution, tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy (ARPES) to study the three-dimensionality (3D) of the bulk electronic structure in WTe 2 , a type II Weyl semimetal. The bulk Fermi surface (FS) consists of two pairs of electron pockets and two pairs of hole pockets along the Χ–Γ–Χ direction as detected by using an incident photon energy of 6.7 eV, which is consistent with the previously reported data. However, if using an incident photon energy of 6.36 eV, another pair of tiny electron pockets is detected on both sides of the Γ point, which is in agreement with the small quantum oscillation frequency peak observed in the magnetoresistance. Therefore, the bulk, 3D FS consists of three pairs of electron pockets and two pairs of hole pockets in total. With the ability of fine tuning the incident photon energy, we demonstrate the strong three-dimensionality of the bulk electronic structure in WTe 2 . Finally, the combination of resistivity and ARPES measurements reveals the complete, and consistent, picture of the bulk electronic structure of this material.« less

Structural consistency analysis of recombinant and wild-type human serum albumin

NASA Astrophysics Data System (ADS)

Cao, Hui-Ling; Sun, Li-Hua; Liu, Li; Li, Jian; Tang, Lin; Guo, Yun-Zhu; Mei, Qi-Bing; He, Jian-Hua; Yin, Da-Chuan

2017-01-01

Recombinant human serum albumin (rHSA) is potential alternatives for human serum albumin (HSA) which may ease severe shortage of HSA worldwide. In theory, rHSA and HSA are the same. Structure decides function. Therefore, the 3D structural consistency analysis of rHSA and HSA is outmost importance, which is the base of their function consistency. In this paper, the crystal structures of rHSA at resolution limit of 2.22 Å and HSA at 2.30 Å were determined by X-ray diffraction (XRD), which were deposited in the Protein Data Bank (PDB) with accession codes 4G03 (rHSA) and 4G04 (HSA). The differences between rHSA and HSA were systematically analyzed from the crystallization behavior, diffraction data and three-dimensional (3D) structure. The superimposed contrasted analysis indicated that rHSA and HSA achieved a structural similarity of 99% with an r.m.s. deviation of 0.397 Å for the corresponding overall Cα atoms. In addition, the number of α-helices in the rHSA or HSA molecule was verified to be 30. As a result, rHSA can potentially replace HSA. The study provides a theoretical and experimental basis for the clinical and additional applications of rHSA. Meanwhile, it is also a good example for applications of genetic engineering.

Short Large-Amplitude Magnetic Structures (SLAMS) at Venus

NASA Technical Reports Server (NTRS)

Collinson, G. A.; Wilson, L. B.; Sibeck, D. G.; Shane, N.; Zhang, T. L.; Moore, T. E.; Coates, A. J.; Barabash, S.

2012-01-01

We present the first observation of magnetic fluctuations consistent with Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock of the planet Venus. Three monolithic magnetic field spikes were observed by the Venus Express on the 11th of April 2009. The structures were approx.1.5->11s in duration, had magnetic compression ratios between approx.3->6, and exhibited elliptical polarization. These characteristics are consistent with the SLAMS observed at Earth, Jupiter, and Comet Giacobini-Zinner, and thus we hypothesize that it is possible SLAMS may be found at any celestial body with a foreshock.

i3Drefine software for protein 3D structure refinement and its assessment in CASP10.

PubMed

Bhattacharya, Debswapna; Cheng, Jianlin

2013-01-01

Protein structure refinement refers to the process of improving the qualities of protein structures during structure modeling processes to bring them closer to their native states. Structure refinement has been drawing increasing attention in the community-wide Critical Assessment of techniques for Protein Structure prediction (CASP) experiments since its addition in 8(th) CASP experiment. During the 9(th) and recently concluded 10(th) CASP experiments, a consistent growth in number of refinement targets and participating groups has been witnessed. Yet, protein structure refinement still remains a largely unsolved problem with majority of participating groups in CASP refinement category failed to consistently improve the quality of structures issued for refinement. In order to alleviate this need, we developed a completely automated and computationally efficient protein 3D structure refinement method, i3Drefine, based on an iterative and highly convergent energy minimization algorithm with a powerful all-atom composite physics and knowledge-based force fields and hydrogen bonding (HB) network optimization technique. In the recent community-wide blind experiment, CASP10, i3Drefine (as 'MULTICOM-CONSTRUCT') was ranked as the best method in the server section as per the official assessment of CASP10 experiment. Here we provide the community with free access to i3Drefine software and systematically analyse the performance of i3Drefine in strict blind mode on the refinement targets issued in CASP10 refinement category and compare with other state-of-the-art refinement methods participating in CASP10. Our analysis demonstrates that i3Drefine is only fully-automated server participating in CASP10 exhibiting consistent improvement over the initial structures in both global and local structural quality metrics. Executable version of i3Drefine is freely available at http://protein.rnet.missouri.edu/i3drefine/.

Outer planet probe engineering model structural tests

NASA Technical Reports Server (NTRS)

Smittkamp, J. A.; Gustin, W. H.; Griffin, M. W.

1977-01-01

A series of proof of concept structural tests was performed on an engineering model of the Outer Planets Atmospheric Entry Probe. The tests consisted of pyrotechnic shock, dynamic and static loadings. The tests partially verified the structural concept.

Generalized Multilevel Structural Equation Modeling

ERIC Educational Resources Information Center

Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

2004-01-01

A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

Controls Astrophysics and Structures Experiment in Space (CASES) advanced studies and planning

NASA Technical Reports Server (NTRS)

Wu, S. T.

1989-01-01

The CASES (Controls, Astrophysics, and Structures Experiment in Space) program consists of a flight demonstration of CSI (Controls-Structures Interactions) technology on the Space Shuttle. The basis structure consists of a 32 m deployable boom with actuators and sensors distributed along its length. Upon deployment from the Orbiter bay, the CASES structure will be characterized dynamically and its deformations controlled by a series of experimental control laws; and cold gas thrusters at its tip will be used to orient the Orbiter to a fixed celestial reference. The scientific observations will consist of hard x-ray imaging, at high resolution, of the Sun and the Galactic center. The hard x-ray observations require stable (few arc min) pointing at these targets for one or more position-sensitive proportional counters in the Orbiter bay, which view the object to be imaged through an aperture-encoding mask at the boom tip. This report gives the concensus developed at the second CASES Science Working Group meeting, which took place at NASA Marshall Space Flight Center May 16-17, 1990. An earlier paper and scientific summaries are available and form the basis for the present discussion.

Architecture of the organic matrix in the sternal CaCO3 deposits of Porcellio scaber (Crustacea, Isopoda).

PubMed

Fabritius, Helge; Walther, Paul; Ziegler, Andreas

2005-05-01

Before the molt terrestrial isopods resorb calcium from the posterior cuticle and store it in large deposits within the first four anterior sternites. In Porcellio scaber the deposits consist of three structurally distinct layers consisting of amorphous CaCO3 (ACC) and an organic matrix that consists of concentric and radial elements. It is thought that the organic matrix plays a role in the structural organization of deposits and in the stabilization of ACC, which is unstable in vitro. In this paper, we present a thorough analysis of the ultrastructure of the organic matrix in the CaCO3 deposits using high-resolution field-emission scanning electron microscopy. The spherules and the homogeneous layer contain an elaborate organic matrix with similar structural organization consisting of concentric reticules and radial strands. The decalcification experiments reveal an inhomogeneous solubility of ACC within the spherules probably caused by variations in the stabilizing properties of matrix components. The transition between the three layers can be explained by changes in the number of spherule nucleation sites.

The Effects of Spelling Consistency on Phonological Awareness: A Comparison of English and German

ERIC Educational Resources Information Center

Goswami, Usha; Ziegler, Johannes C.; Richardson, Ulla

2005-01-01

Within alphabetic languages, spelling-to-sound consistency can differ dramatically. For example, English and German are very similar in their phonological and orthographic structure but not in their consistency. In English the letter "a" is pronounced differently in the words "bank," "ball," and "park,"…

Assessing Videogrammetry for Static Aeroelastic Testing of a Wind-Tunnel Model

NASA Technical Reports Server (NTRS)

Spain, Charles V.; Heeg, Jennifer; Ivanco, Thomas G.; Barrows, Danny A.; Florance, James R.; Burner, Alpheus W.; DeMoss, Joshua; Lively, Peter S.

2004-01-01

The Videogrammetric Model Deformation (VMD) technique, developed at NASA Langley Research Center, was recently used to measure displacements and local surface angle changes on a static aeroelastic wind-tunnel model. The results were assessed for consistency, accuracy and usefulness. Vertical displacement measurements and surface angular deflections (derived from vertical displacements) taken at no-wind/no-load conditions were analyzed. For accuracy assessment, angular measurements were compared to those from a highly accurate accelerometer. Shewhart's Variables Control Charts were used in the assessment of consistency and uncertainty. Some bad data points were discovered, and it is shown that the measurement results at certain targets were more consistent than at other targets. Physical explanations for this lack of consistency have not been determined. However, overall the measurements were sufficiently accurate to be very useful in monitoring wind-tunnel model aeroelastic deformation and determining flexible stability and control derivatives. After a structural model component failed during a highly loaded condition, analysis of VMD data clearly indicated progressive structural deterioration as the wind-tunnel condition where failure occurred was approached. As a result, subsequent testing successfully incorporated near- real-time monitoring of VMD data in order to ensure structural integrity. The potential for higher levels of consistency and accuracy through the use of statistical quality control practices are discussed and recommended for future applications.

Generalized fractional supertrace identity for Hamiltonian structure of NLS-MKdV hierarchy with self-consistent sources

NASA Astrophysics Data System (ADS)

Dong, Huan He; Guo, Bao Yong; Yin, Bao Shu

2016-06-01

In the paper, based on the modified Riemann-Liouville fractional derivative and Tu scheme, the fractional super NLS-MKdV hierarchy is derived, especially the self-consistent sources term is considered. Meanwhile, the generalized fractional supertrace identity is proposed, which is a beneficial supplement to the existing literature on integrable system. As an application, the super Hamiltonian structure of fractional super NLS-MKdV hierarchy is obtained.

Generalized self-consistent method for predicting the effective elastic properties of composites with random hybrid structures

NASA Astrophysics Data System (ADS)

Pan'kov, A. A.

1997-05-01

The feasibility of using a generalized self-consistent method for predicting the effective elastic properties of composites with random hybrid structures has been examined. Using this method, the problem is reduced to solution of simpler special averaged problems for composites with single inclusions and corresponding transition layers in the medium examined. The dimensions of the transition layers are defined by correlation radii of the composite random structure of the composite, while the heterogeneous elastic properties of the transition layers take account of the probabilities for variation of the size and configuration of the inclusions using averaged special indicator functions. Results are given for a numerical calculation of the averaged indicator functions and analysis of the effect of the micropores in the matrix-fiber interface region on the effective elastic properties of unidirectional fiberglass—epoxy using the generalized self-consistent method and compared with experimental data and reported solutions.

Hierarchical Structure of the Eysenck Personality Inventory in a Large Population Sample: Goldberg's Trait-Tier Mapping Procedure

PubMed Central

Chapman, Benjamin P.; Weiss, Alexander; Barrett, Paul; Duberstein, Paul

2014-01-01

The structure of the Eysenck Personality Inventory (EPI) is poorly understood, and applications have mostly been confined to the broad Neuroticism, Extraversion, and Lie scales. Using a hierarchical factoring procedure, we mapped the sequential differentiation of EPI scales from broad, molar factors to more specific, molecular factors, in a UK population sample of over 6500 persons. Replicable facets at the lowest tier of Neuroticism included emotional fragility, mood lability, nervous tension, and rumination. The lowest order set of replicable Extraversion facets consisted of social dynamism, sociotropy, decisiveness, jocularity, social information seeking, and impulsivity. The Lie scale consisted of an interpersonal virtue and a behavioral diligence facet. Users of the EPI may be well served in some circumstances by considering its broad Neuroticism, Extraversion, and Lie scales as multifactorial, a feature that was explicitly incorporated into subsequent Eysenck inventories and is consistent with other hierarchical trait structures. PMID:25983361

Structure of random discrete spacetime

NASA Technical Reports Server (NTRS)

Brightwell, Graham; Gregory, Ruth

1991-01-01

The usual picture of spacetime consists of a continuous manifold, together with a metric of Lorentzian signature which imposes a causal structure on the spacetime. A model, first suggested by Bombelli et al., is considered in which spacetime consists of a discrete set of points taken at random from a manifold, with only the causal structure on this set remaining. This structure constitutes a partially ordered set (or poset). Working from the poset alone, it is shown how to construct a metric on the space which closely approximates the metric on the original spacetime manifold, how to define the effective dimension of the spacetime, and how such quantities may depend on the scale of measurement. Possible desirable features of the model are discussed.

The structure of random discrete spacetime

NASA Technical Reports Server (NTRS)

Brightwell, Graham; Gregory, Ruth

1990-01-01

The usual picture of spacetime consists of a continuous manifold, together with a metric of Lorentzian signature which imposes a causal structure on the spacetime. A model, first suggested by Bombelli et al., is considered in which spacetime consists of a discrete set of points taken at random from a manifold, with only the causal structure on this set remaining. This structure constitutes a partially ordered set (or poset). Working from the poset alone, it is shown how to construct a metric on the space which closely approximates the metric on the original spacetime manifold, how to define the effective dimension of the spacetime, and how such quantities may depend on the scale of measurement. Possible desirable features of the model are discussed.

Compact Radiative Control Structures for Millimeter Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari D.; Chuss, David T.; Chervenak, James A.; Henry, Ross M.; Moseley, s. Harvey; Wollack, Edward J.

2010-01-01

We have designed, fabricated, and tested compact radiative control structures, including antireflection coatings and resonant absorbers, for millimeter through submillimeter wave astronomy. The antireflection coatings consist of micromachined single crystal silicon dielectric sub-wavelength honeycombs. The effective dielectric constant of the structures is set by the honeycomb cell geometry. The resonant absorbers consist of pieces of solid single crystal silicon substrate and thin phosphorus implanted regions whose sheet resistance is tailored to maximize absorption by the structure. We present an implantation model that can be used to predict the ion energy and dose required for obtaining a target implant layer sheet resistance. A neutral density filter, a hybrid of a silicon dielectric honeycomb with an implanted region, has also been fabricated with this basic approach. These radiative control structures are scalable and compatible for use large focal plane detector arrays.

Neutron and Atomic Resolution X-ray Structures of a Lytic Polysaccharide Monooxygenase Reveal Copper-Mediated Dioxygen Binding and Evidence for N-Terminal Deprotonation

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

Bacik, John-Paul; Mekasha, Sophanit; Forsberg, Zarah

A 1.1 Å resolution, room-temperature X-ray structure and a 2.1 Å resolution neutron structure of a chitin-degrading lytic polysaccharide monooxygenase domain from the bacterium Jonesia denitrificans (JdLPMO10A) show a putative dioxygen species equatorially bound to the active site copper. We found that both structures show an elongated density for the dioxygen, most consistent with a Cu(II)-bound peroxide. The coordination environment is consistent with Cu(II). Furthermore, in the neutron and X-ray structures, difference maps reveal the N-terminal amino group, involved in copper coordination, is present as a mixed ND 2 and ND –, suggesting a role for the copper ion inmore » shifting the pK a of the amino terminus.« less

Neutron and Atomic Resolution X-ray Structures of a Lytic Polysaccharide Monooxygenase Reveal Copper-Mediated Dioxygen Binding and Evidence for N-Terminal Deprotonation

DOE PAGES

Bacik, John-Paul; Mekasha, Sophanit; Forsberg, Zarah; ...

2017-05-08

A 1.1 Å resolution, room-temperature X-ray structure and a 2.1 Å resolution neutron structure of a chitin-degrading lytic polysaccharide monooxygenase domain from the bacterium Jonesia denitrificans (JdLPMO10A) show a putative dioxygen species equatorially bound to the active site copper. We found that both structures show an elongated density for the dioxygen, most consistent with a Cu(II)-bound peroxide. The coordination environment is consistent with Cu(II). Furthermore, in the neutron and X-ray structures, difference maps reveal the N-terminal amino group, involved in copper coordination, is present as a mixed ND 2 and ND –, suggesting a role for the copper ion inmore » shifting the pK a of the amino terminus.« less

The predicted secondary structures of class I fructose-bisphosphate aldolases.

PubMed Central

Sawyer, L; Fothergill-Gilmore, L A; Freemont, P S

1988-01-01

The results of several secondary-structure prediction programs were combined to produce an estimate of the regions of alpha-helix, beta-sheet and reverse turns for fructose-bisphosphate aldolases from human and rat muscle and liver, from Trypanosoma brucei and from Drosophila melanogaster. All the aldolase sequences gave essentially the same pattern of secondary-structure predictions despite having sequences up to 50% different. One exception to this pattern was an additional strongly predicted helix in the rat liver and Drosophila enzymes. Regions of relatively high sequence variation generally were predicted as reverse turns, and probably occur as surface loops. Most of the positions corresponding to exon boundaries are located between regions predicted to have secondary-structural elements consistent with a compact structure. The predominantly alternating alpha/beta structure predicted is consistent with the alpha/beta-barrel structure indicated by preliminary high-resolution X-ray diffraction studies on rabbit muscle aldolase [Sygusch, Beaudry & Allaire (1986) Biophys. J. 49, 287a]. Images Fig. 1. (cont.) Fig. 1. PMID:3128269

Hospital Anxiety and Depression Scale: Factor Structure, Internal Consistency and Convergent Validity in Patients with Dizziness.

PubMed

Piker, Erin G; Kaylie, David M; Garrison, Douglas; Tucci, Debara L

2015-01-01

Psychiatric comorbidities, particularly anxiety-related pathologies, are often observed in dizzy patients. The Hospital Anxiety and Depression Scale (HADS) is a widely used self-report instrument used to screen for anxiety and depression in medical outpatient settings. The purpose of this study was to assess the factor structure, internal consistency and convergent validity of the HADS in an unselected group of patients with dizziness. The HADS and the Dizziness Handicap Inventory (DHI) were administered to 205 dizzy patients. An exploratory factor analysis was conducted and indicated a 3-factor structure, inconsistent with the 2-subscale structure (i.e. anxiety and depression) of the HADS. The total scale was found to be internally consistent, and convergent validity, as assessed using the DHI, was acceptable. Overall findings suggest that the HADS should not be used as a tool for psychiatric differential diagnosis, but rather as a helpful screener for general psychiatric distress in the two domains of psychiatric illness most germane in dizzy patients. © 2015 S. Karger AG, Basel.

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

DOE PAGES

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph; ...

2018-02-06

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

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

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Cross-correlation between the 170 GHz survey map and the COBE differential microwave radiometer first-year maps

NASA Technical Reports Server (NTRS)

Ganga, Ken; Cheng, ED; Meyer, Stephan; Page, Lyman

1993-01-01

This letter describes results of a cross-correlation between the 170 GHz partial-sky survey, made with a 3.8 deg beam balloon-borne instrument, and the COBE DMR 'Fit Technique' reduced galaxy all-sky map with a beam of 7 deg. The strong correlation between the data sets implies that the observed structure is consistent with thermal variations in a 2.7 K emitter. A chi-square analysis applied to the correlation function rules out the assumption that there is no structure in either of the two maps. A second test shows that if the DMR map has structure but the 170 GHz map does not, the probability of obtaining the observed correlation is small. Further analyses support the assumption that both maps have structure and that the 170 GHz-DMR cross-correlation is consistent with the analogous DMR correlation function. Maps containing various combinations of noise and Harrison-Zel'dovich power spectra are simulated and correlated to reinforce the result. The correlation provides compelling evidence that both instruments have observed fluctuations consistent with anisotropies in the cosmic microwave background.

Group-III nitride VCSEL structures grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Ng, HockMin; Moustakas, Theodore D.

2000-07-01

III-nitride VCSEL structures designed for electron-beam pumping have been grown by molecular beam epitaxy (MBE). The structures consist of a sapphire substrate on which an AlN/GaN distributed Bragg reflector (DBR) with peak reflectance >99% at 402 nm is deposited. The active region consists of a 2-(lambda) cavity with 25 In0.1Ga0.9N/GaN multiquantum wells (MQWs) whose emission coincides with the high reflectance region of the DBR. The thicknesses of the InGaN wells and the GaN barriers are 35 angstrom and 75 angstrom respectively. The top reflector consists of a silver metallic mirror which prevents charging effects during electron-beam pumping. The structure was pumped from the top- side with a cw electron-beam using a modified cathodoluminescence (CL) system mounted on a scanning electron microscope chamber. Light output was collected from the polished sapphire substrate side. Measurements performed at 100 K showed intense emission at 407 nm with narrowing of the linewidth with increasing beam current. A narrow emission linewidth of 0.7 nm was observed indicating the onset of stimulated emission.

Amyloplast sedimentation dynamics in maize columella cells support a new model for the gravity-sensing apparatus of roots

NASA Technical Reports Server (NTRS)

Yoder, T. L.; Zheng, H. Q.; Todd, P.; Staehelin, L. A.

2001-01-01

Quantitative analysis of statolith sedimentation behavior was accomplished using videomicroscopy of living columella cells of corn (Zea mays) roots, which displayed no systematic cytoplasmic streaming. Following 90 degrees rotation of the root, the statoliths moved downward along the distal wall and then spread out along the bottom with an average velocity of 1.7 microm min(-1). When statolith trajectories traversed the complete width or length of the cell, they initially moved horizontally toward channel-initiation sites and then moved vertically through the channels to the lower side of the reoriented cell where they again dispersed. These statoliths exhibited a significantly lower average velocity than those sedimenting on distal-to-side trajectories. In addition, although statoliths undergoing distal-to-side sedimentation began at their highest velocity and slowed monotonically as they approached the lower cell membrane, statoliths crossing the cell's central region remained slow initially and accelerated to maximum speed once they reached a channel. The statoliths accelerated sooner, and the channeling effect was less pronounced in roots treated with cytochalasin D. Parallel ultrastructural studies of high-pressure frozen-freeze-substituted columella cells suggest that the low-resistance statolith pathway in the cell periphery corresponds to the sharp interface between the endoplasmic reticulum (ER)-rich cortical and the ER-devoid central region of these cells. The central region is also shown to contain an actin-based cytoskeletal network in which the individual, straight, actin-like filaments are randomly distributed. To explain these findings as well as the results of physical simulation experiments, we have formulated a new, tensegrity-based model of gravity sensing in columella cells. This model envisages the cytoplasm as pervaded by an actin-based cytoskeletal network that is denser in the ER-devoid central region than in the ER-rich cell cortex and is linked to stretch receptors in the plasma membrane. Sedimenting statoliths are postulated to produce a directional signal by locally disrupting the network and thereby altering the balance of forces acting on the receptors in different plasma membrane regions.

Amyloplast Sedimentation Dynamics in Maize Columella Cells Support a New Model for the Gravity-Sensing Apparatus of Roots1

PubMed Central

Yoder, Thomas L.; Zheng, Hui-qiong; Todd, Paul; Staehelin, L. Andrew

2001-01-01

Quantitative analysis of statolith sedimentation behavior was accomplished using videomicroscopy of living columella cells of corn (Zea mays) roots, which displayed no systematic cytoplasmic streaming. Following 90° rotation of the root, the statoliths moved downward along the distal wall and then spread out along the bottom with an average velocity of 1.7 μm min−1. When statolith trajectories traversed the complete width or length of the cell, they initially moved horizontally toward channel-initiation sites and then moved vertically through the channels to the lower side of the reoriented cell where they again dispersed. These statoliths exhibited a significantly lower average velocity than those sedimenting on distal-to-side trajectories. In addition, although statoliths undergoing distal-to-side sedimentation began at their highest velocity and slowed monotonically as they approached the lower cell membrane, statoliths crossing the cell's central region remained slow initially and accelerated to maximum speed once they reached a channel. The statoliths accelerated sooner, and the channeling effect was less pronounced in roots treated with cytochalasin D. Parallel ultrastructural studies of high-pressure frozen-freeze-substituted columella cells suggest that the low-resistance statolith pathway in the cell periphery corresponds to the sharp interface between the endoplasmic reticulum (ER)-rich cortical and the ER-devoid central region of these cells. The central region is also shown to contain an actin-based cytoskeletal network in which the individual, straight, actin-like filaments are randomly distributed. To explain these findings as well as the results of physical simulation experiments, we have formulated a new, tensegrity-based model of gravity sensing in columella cells. This model envisages the cytoplasm as pervaded by an actin-based cytoskeletal network that is denser in the ER-devoid central region than in the ER-rich cell cortex and is linked to stretch receptors in the plasma membrane. Sedimenting statoliths are postulated to produce a directional signal by locally disrupting the network and thereby altering the balance of forces acting on the receptors in different plasma membrane regions. PMID:11161060

Amyloplast sedimentation dynamics in maize columella cells support a new model for the gravity-sensing apparatus of roots.

PubMed

Yoder, T L; Zheng, H Q; Todd, P; Staehelin, L A

2001-02-01

Quantitative analysis of statolith sedimentation behavior was accomplished using videomicroscopy of living columella cells of corn (Zea mays) roots, which displayed no systematic cytoplasmic streaming. Following 90 degrees rotation of the root, the statoliths moved downward along the distal wall and then spread out along the bottom with an average velocity of 1.7 microm min(-1). When statolith trajectories traversed the complete width or length of the cell, they initially moved horizontally toward channel-initiation sites and then moved vertically through the channels to the lower side of the reoriented cell where they again dispersed. These statoliths exhibited a significantly lower average velocity than those sedimenting on distal-to-side trajectories. In addition, although statoliths undergoing distal-to-side sedimentation began at their highest velocity and slowed monotonically as they approached the lower cell membrane, statoliths crossing the cell's central region remained slow initially and accelerated to maximum speed once they reached a channel. The statoliths accelerated sooner, and the channeling effect was less pronounced in roots treated with cytochalasin D. Parallel ultrastructural studies of high-pressure frozen-freeze-substituted columella cells suggest that the low-resistance statolith pathway in the cell periphery corresponds to the sharp interface between the endoplasmic reticulum (ER)-rich cortical and the ER-devoid central region of these cells. The central region is also shown to contain an actin-based cytoskeletal network in which the individual, straight, actin-like filaments are randomly distributed. To explain these findings as well as the results of physical simulation experiments, we have formulated a new, tensegrity-based model of gravity sensing in columella cells. This model envisages the cytoplasm as pervaded by an actin-based cytoskeletal network that is denser in the ER-devoid central region than in the ER-rich cell cortex and is linked to stretch receptors in the plasma membrane. Sedimenting statoliths are postulated to produce a directional signal by locally disrupting the network and thereby altering the balance of forces acting on the receptors in different plasma membrane regions.

Ash Shutbah: A possible impact structure in Saudi Arabia

NASA Astrophysics Data System (ADS)

Gnos, Edwin; Hofmann, Beda A.; Schmieder, Martin; Al-Wagdani, Khalid; Mahjoub, Ayman; Al-Solami, Abdulaziz A.; Habibullah, Siddiq N.; Matter, Albert; Alwmark, Carl

2014-10-01

We have investigated the Ash Shutbah circular structure in central Saudi Arabia (21°37'N 45°39'E) using satellite imagery, field mapping, thin-section petrography, and X-ray diffraction of collected samples. The approximately 2.1 km sized structure located in flat-lying Jurassic Tuwaiq Mountain Limestone has been nearly peneplained by erosional processes. Satellite and structural data show a central area consisting of Dhruma Formation sandstones with steep bedding and tight folds plunging radially outward. Open folding occurs in displaced, younger Tuwaiq Mountain Limestone Formation blocks surrounding the central area, but is absent outside the circular structure. An approximately 60 cm thick, unique folded and disrupted orthoquartzitic sandstone marker bed occurring in the central area of the structure is found 140 m deeper in undisturbed escarpment outcrops located a few hundred meters west of the structure. With exception of a possible concave shatter cone found in the orthoquartzite of the central area, other diagnostic shock features are lacking. Some quartz-rich sandstones from the central area show pervasive fracturing of quartz grains with common concussion fractures. This deformation was followed by an event of quartz dissolution and calcite precipitation consistent with local sea- or groundwater heating. The combination of central stratigraphic uplift of 140 m, concussion features in discolored sandstone, outward-dipping concentric folds in the central area, deformation restricted to the rocks of the ring structure, a complex circular structure of 2.1 km diameter that appears broadly consistent with what one would expect from an impact structure in sedimentary targets, and a possible shatter cone all point to an impact origin of the Ash Shutbah structure. In fact, the Ash Shutbah structure appears to be a textbook example of an eroded, complex impact crater located in flat-lying sedimentary rocks, where the undisturbed stratigraphic section can be studied in escarpment outcrops in the vicinity of the structure.

Evidence for magnetic energy storage in coronal active regions

NASA Technical Reports Server (NTRS)

Krieger, A. S.; De Feiter, L. D.; Vaiana, G. S.

1976-01-01

Examination of X-ray images obtained by the S-054 X-ray spectrographic telescope on Skylab shows the presence of some atypical X-ray-emitting coronal structures in active regions which are not consistent with potential extrapolations of photospheric magnetic fields. Analysis of the observed temporal changes in the X-ray-emitting active-region structures demonstrates that the majority of these consist of brightness changes representing temperature (and perhaps density) variations of the material in the loops.

Improved solubility of DNA in recyclable and reusable bio-based deep eutectic solvents with long-term structural and chemical stability.

PubMed

Mondal, Dibyendu; Sharma, Mukesh; Mukesh, Chandrakant; Gupta, Vishal; Prasad, Kamalesh

2013-10-25

The solubility of DNA in bio-based deep eutectic solvents (DESs) consisting of mixtures of choline chloride with levulinic acid, glycerol, ethylene glycol, sorbitol and resorcinol was investigated. The macromolecule was found to be soluble and chemically and structurally stable in DESs consisting of mixtures containing glycerol and ethylene glycol. Furthermore recyclability of the DESs was demonstrated over three consecutive reuses in DNA dissolution.

Physics and chemistry of MoS2 intercalation compounds

NASA Technical Reports Server (NTRS)

Woollam, J. A.; Somoano, R. B.

1977-01-01

An investigation is made of the physics and chemistry of MoS2 intercalation compounds. These compounds may be separated into two groups according to their stoichiometry, structure and superconducting properties. The first group consists of Na, Ca, and Sr intercalates, and the second group consists of K, Rb, and Cs intercalates. Particular attention is given to the structure of the electronic energy band and to the normal state and superconducting properties of these compounds.

Story Structures: Comments on Recent Literature.

ERIC Educational Resources Information Center

Peterson, Gordon

Several theories of story structure are reviewed in this paper, including those of D. Rumelhart, R. Schank, and T. van Dijk. Examples are given of Rumelhart's story grammar consisting of elements such as setting, episodes, events, and reactions that must be present to form a coherent structure. Schank's contribution to story structure theory is…

Two classes of ODE models with switch-like behavior.

PubMed

Just, Winfried; Korb, Mason; Elbert, Ben; Young, Todd

2013-12-01

In cases where the same real-world system can be modeled both by an ODE system ⅅ and a Boolean system , it is of interest to identify conditions under which the two systems will be consistent, that is, will make qualitatively equivalent predictions. In this note we introduce two broad classes of relatively simple models that provide a convenient framework for studying such questions. In contrast to the widely known class of Glass networks, the right-hand sides of our ODEs are Lipschitz-continuous. We prove that if has certain structures, consistency between ⅅ and is implied by sufficient separation of time scales in one class of our models. Namely, if the trajectories of are "one-stepping" then we prove a strong form of consistency and if has a certain monotonicity property then there is a weaker consistency between ⅅ and . These results appear to point to more general structure properties that favor consistency between ODE and Boolean models.

Dissipative structures, machines, and organisms: A perspective

NASA Astrophysics Data System (ADS)

Kondepudi, Dilip; Kay, Bruce; Dixon, James

2017-10-01

Self-organization in nonequilibrium systems resulting in the formation of dissipative structures has been studied in a variety of systems, most prominently in chemical systems. We present a study of a voltage-driven dissipative structure consisting of conducting beads immersed in a viscous medium of oil. In this simple system, we observed remarkably complex organism-like behavior. The dissipative structure consists of a tree structure that spontaneously forms and moves like a worm and exhibits many features characteristic of living organisms. The complex motion of the beads driven by the applied field, the dipole-dipole interaction between the beads, and the hydrodynamic flow of the viscous medium result in a time evolution of the tree structure towards states of lower resistance or higher dissipation and thus higher rates of entropy production. The resulting end-directed evolution manifests as the tree moving to locations seeking higher current, the current that sustains its structure and dynamics. The study of end-directed evolution in the dissipative structure gives us a means to distinguish the fundamental difference between machines and organisms and opens a path for the formulation of physics of organisms.

The Analytical Pragmatic Structure of Procedural Due Process: A Framework for Inquiry in Administrative Decision Making.

ERIC Educational Resources Information Center

Fisher, James E.; Sealey, Ronald W.

The study describes the analytical pragmatic structure of concepts and applies this structure to the legal concept of procedural due process. This structure consists of form, purpose, content, and function. The study conclusions indicate that the structure of the concept of procedural due process, or any legal concept, is not the same as the…

Examining conifer canopy structural complexity across forest ages and elevations with LiDAR data

Treesearch

Van R. Kane; Jonathan D. Bakker; Robert J. McGaughey; James A. Lutz; Rolf F. Gersonde; Jerry F. Franklin

2010-01-01

LiDAR measurements of canopy structure can be used to classify forest stands into structural stages to study spatial patterns of canopy structure, identify habitat, or plan management actions. A key assumption in this process is that differences in canopy structure based on forest age and elevation are consistent with predictions from models of stand development. Three...

Control-Structure Ratings on the Fox River at McHenry and Algonquin, Illinois

USGS Publications Warehouse

Straub, Timothy D.; Johnson, Gary P.; Hortness, Jon E.; Parker, Joseph R.

2009-01-01

The Illinois Department of Natural Resources-Office of Water Resources operates control structures on a reach of the Fox River in northeastern Illinois between McHenry and Algonquin. The structures maintain water levels in the river for flood-control and recreational purposes. This report documents flow ratings for hinged-crest gates, a broad-crested weir, sluice gates, and an ogee spillway on the control structures at McHenry and Algonquin. The ratings were determined by measuring headwater and tailwater stage along with streamflow at a wide range of flows at different gate openings. Standard control-structure rating techniques were used to rate each control structure. The control structures at McHenry consist of a 221-feet(ft)-long broad-crested weir, a 4-ft-wide fish ladder, a 50-ft-wide hinged-crest gate, five 13.75-ft-wide sluice gates, and a navigational lock. Sixty measurements were used to rate the McHenry structures. The control structures at Algonquin consist of a 242-ft-long ogee spillway and a 50-ft-wide hinged-crest gate. Forty-one measurements were used to rate the Algonquin control structures.

Viscous-pendulum damper suppresses structural vibrations

NASA Technical Reports Server (NTRS)

Reed, W. H., III

1964-01-01

The viscous pendulum damper consists of a cylinder containing round trays on which round lead slugs rest. When assembled, the container is filled with a viscous liquid and attached, with axis vertical, to the structure. The device permits varying the damping of structural vibrations.

Predictability of littoral-zone fish communities through ontogeny in Lake Texoma, Oklahoma-Texas, USA

USGS Publications Warehouse

Eggleton, M.A.; Ramirez, R.; Hargrave, C.W.; Gido, K.B.; Masoner, J.R.; Schnell, G.D.; Matthews, W.J.

2005-01-01

We sampled larval, juvenile and adult fishes from littoral-zone areas of a large reservoir (Lake Texoma, Oklahoma-Texas) (1) to characterize environmental factors that influenced fish community structure, (2) to examine how consistent fish-environment relationships were through ontogeny (i.e., larval vs. juvenile and adult), and (3) to measure the concordance of larval communities sampled during spring to juvenile and adult communities sampled at the same sites later in the year. Larval, juvenile and adult fish communities were dominated by Atherinidae (mainly inland silverside, Menidia beryllina) and Moronidae (mainly juvenile striped bass, Morone saxatilis) and were consistently structured along a gradient of site exposure to prevailing winds and waves. Larval, juvenile and adult communities along this gradient varied from atherinids and moronids at highly exposed sites to mostly centrarchids (primarily Lepomis and Micropterus spp.) at protected sites. Secondarily, zooplankton densities, water clarity, and land-use characteristics were related to fish community structure. Rank correlation analyses and Mantel tests indicated that the spatial consistency and predictability of fish communities was high as larval fishes sampled during spring were concordant with juvenile and adult fishes sampled at the same sites during summer and fall in terms of abundance, richness, and community structure. We propose that the high predictability and spatial consistency of littoral-zone fishes in Lake Texoma was a function of relatively simple communities (dominated by 1-2 species) that were structured by factors, such as site exposure to winds and waves, that varied little through time. ?? Springer 2005.

Staging in polyacetylene-iodine conductors

NASA Astrophysics Data System (ADS)

Baughman, R. H.; Murthy, N. S.; Miller, G. G.; Shacklette, L. W.

1983-07-01

Evidence is presented for the existence of highly conducting polyacetylene complexes with structures related to high-stage graphite, as well as structures related to first-stage graphite. X-ray diffraction measurements on polyacetylene-iodine complexes indicate equatorial lines at 7.7-8.0 and 13.8-14.3 Å. The shorter spacing arises in part from a structure in which iodine-rich planes alternate with planes of polyacetylene chains. The longer spacing, which disappears upon atmospheric exposure, is consistent with a structure analogous to third-stage graphite in which dopant-rich planes are separated by three close-packed planes of polyacetylene chains. The third-stage complex can be viewed as a perturbation of the structure of undoped polyacetylene, with the region between dopant layers consisting essentially of a one unit cell thickness of the parent polymer structure. Packing calculations for this model, in which a linear column of anions (I3- and/or I5-) displaces either every chain or every other chain in the dopant-rich layer, provide an interlayer spacing which is equal to that observed. Evidence consistent with third-stage structures (with both fractional occupation and complete occupation of the dopant plane) is also found by reexamination of published sorption data, which provides slope changes at close to the calculated limiting compositions for these structures [(CHI0.056)x and (CHI0.13)x]. However, a first-stage structure with alternating dopant arrays and polymer chains in the dopant plane [for which (CHI0.13)x is calculated] provides a better explanation for the second slope change, as well as for the composition obtained under dynamic vacuum, (CHI0.14)x. These results for iodine complexes are compared with those derived for the group VA halide complexes of polyacetylene.

Synthesis of regional crust and upper-mantle structure from seismic and gravity data

NASA Technical Reports Server (NTRS)

Alexander, S. S.; Lavin, P. M.

1979-01-01

Available seismic and ground based gravity data are combined to infer the three dimensional crust and upper mantle structure in selected regions. This synthesis and interpretation proceeds from large-scale average models suitable for early comparison with high-altitude satellite potential field data to more detailed delineation of structural boundaries and other variations that may be significant in natural resource assessment. Seismic and ground based gravity data are the primary focal point, but other relevant information (e.g. magnetic field, heat flow, Landsat imagery, geodetic leveling, and natural resources maps) is used to constrain the structure inferred and to assist in defining structural domains and boundaries. The seismic data consists of regional refraction lines, limited reflection coverage, surface wave dispersion, teleseismic P and S wave delay times, anelastic absorption, and regional seismicity patterns. The gravity data base consists of available point gravity determinations for the areas considered.

"On Second Thoughts…": Changes of Mind as an Indication of Competing Knowledge Structures

NASA Astrophysics Data System (ADS)

Wilson, Kate F.; Low, David J.

2015-09-01

A review of student answers to diagnostic questions concerned with Newton's Laws showed a tendency for some students to change their answer to a question when the following question caused them to think more about the situation. We investigate this behavior and interpret it in the framework of the resource model; in particular, a weak Newton's Third Law structure being dominated by an inconsistent Newton's Second Law (or "Net Force") structure, in the absence of a strong, consistent Newtonian structure. This observation highlights the hidden problem in instruction where the implicit use of Newton's Third Law is dominated by the explicit conceptual and mathematical application of Newton's Second Law, both within individual courses and across a degree program. To facilitate students' development of a consistent Newtonian knowledge structure, it is important that instructors highlight the interrelated nature of Newton's Laws in problem solving.

Color tunable monolithic InGaN/GaN LED having a multi-junction structure.

PubMed

Kong, Duk-Jo; Kang, Chang-Mo; Lee, Jun-Yeob; Kim, James; Lee, Dong-Seon

2016-03-21

In this study, we have fabricated a blue-green color-tunable monolithic InGaN/GaN LED having a multi-junction structure with three terminals. The device has an n-p-n structure consisting of a green and a blue active region, i.e., an n-GaN / blue-MQW / p-GaN / green-MQW / n-GaN / Al₂O₃ structure with three terminals for independently controlling the two active regions. To realize this LED structure, a typical LED consisting of layers of n-GaN, blue MQW, and p-GaN is regrown on a conventional green LED by using a metal organic chemical vapor deposition (MOCVD) method. We explain detailed mechanisms of three operation modes which are the green, blue, and cyan mode. Moreover, we discuss optical properties of the device.

Base structure consisting of an endothelialized vascular-tree network and hepatocytes for whole liver engineering.

PubMed

Shirakigawa, Nana; Takei, Takayuki; Ijima, Hiroyuki

2013-12-01

Reconstructed liver has been desired as a liver substitute for transplantation. However, reconstruction of a whole liver has not been achieved because construction of a vascular network at an organ scale is very difficult. We focused on decellularized liver (DC-liver) as an artificial scaffold for the construction of a hierarchical vascular network. In this study, we obtained DC-liver and the tubular network structure in which both portal vein and hepatic vein systems remained intact. Furthermore, endothelialization of the tubular structure in DC-liver was achieved, which prevented blood leakage from the tubular structure. In addition, hepatocytes suspended in a collagen sol were injected from the surroundings using a syringe as a suitable procedure for liver cell inoculation. In summary, we developed a base structure consisting of an endothelialized vascular-tree network and hepatocytes for whole liver engineering. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Synthesis, crystal structure and electronic structure of the binary phase Rh2Cd5

NASA Astrophysics Data System (ADS)

Koley, Biplab; Chatterjee, S.; Jana, Partha P.

2017-02-01

A new phase in the Rh-Cd binary system - Rh2Cd5 has been identified and characterized by single crystal X-ray diffraction and Energy dispersive X-ray analysis. The stoichiometric compound Rh2Cd5 crystallizes with a unit cell containing 14 atoms, in the orthorhombic space group Pbam (55). The crystal structure of Rh2Cd5 can be described as a defect form of the In3Pd5 structure with ordered vacancies, formed of two 2D atomic layers with the stacking sequence: ABAB. The A type layers consist of (3.6.3.6)-Kagomé nets of Cd atoms while the B type layers consist of (35) (37)- nets of both Cd and Rh atoms. The stability of this line phase is investigated by first principle electronic structure calculations on the model of ordered Rh2Cd5.

Atom redistribution and multilayer structure in NiTi shape memory alloy induced by high energy proton irradiation

NASA Astrophysics Data System (ADS)

Wang, Haizhen; Yi, Xiaoyang; Zhu, Yingying; Yin, Yongkui; Gao, Yuan; Cai, Wei; Gao, Zhiyong

2017-10-01

The element distribution and surface microstructure in NiTi shape memory alloys exposed to 3 MeV proton irradiation were investigated. Redistribution of the alloying element and a clearly visible multilayer structure consisting of three layers were observed on the surface of NiTi shape memory alloys after proton irradiation. The outermost layer consists primarily of a columnar-like TiH2 phase with a tetragonal structure, and the internal layer is primarily comprised of a bcc austenite phase. In addition, the Ti2Ni phase, with an fcc structure, serves as the transition layer between the outermost and internal layer. The above-mentioned phenomenon is attributed to the preferential sputtering of high energy protons and segregation induced by irradiation.

The crystal and magnetic structures of Sr 2LaFe 3O 8

NASA Astrophysics Data System (ADS)

Battle, P. D.; Gibb, T. C.; Lightfoot, P.

1990-02-01

The crystal and magnetic structures of the anion-deficient perovskite Sr 2LaFe 3O 8 (space group Pmma, a = 5.5095(1), b = 11.8845(5), c = 5.6028(1)AÅ) have been refined from X-ray and neutron powder diffraction data collected at room temperature. The crystal structure consists of layers of octahedral (O) and tetrahedral (T) iron-oxygen polyhedra arranged in the stacking sequence … OOTOOT … perpendicular to theyˆaxis of the unit cell. The magnetic structure is that of a G-type antiferromagnet with ordered magnetic moments of 3.77(5) and 3.15(11) μ B at the octahedral and tetrahedral sites, respectively. The low moment at the tetrahedral site is consistent with the observed disorder and magnetic anisotropy.

Skeletonization applied to magnetic resonance angiography images

NASA Astrophysics Data System (ADS)

Nystroem, Ingela

1998-06-01

When interpreting and analyzing magnetic resonance angiography images, the 3D overall tree structure and the thickness of the blood vessels are of interest. This shape information may be easier to obtain from the skeleton of the blood vessels. Skeletonization of digital volume objects denotes either reduction to a 2D structure consisting of 3D surfaces, and curves, or reduction to a 1D structure consisting of 3D curves only. Thin elongated objects, such as blood vessels, are well suited for reduction to curve skeletons. Our results indicate that the tree structure of the vascular system is well represented by the skeleton. Positions for possible artery stenoses may be identified by locating local minima in curve skeletons, where the skeletal voxels are labeled with the distance to the original background.

Confirmatory Factor and Rasch Analyses Support a Revised 14-Item Version of the Organizational, Policies, and Practices (OPP) Scale.

PubMed

Shi, Qiyun; MacDermid, Joy C; Tang, Kenneth; Sinden, Kathryn E; Walton, Dave; Grewal, Ruby

2017-06-01

Background The long version of the organizational, policies and practices (OPP) had a high burden and short versions were developed to solve this drawback. The 11-item version showed promise, but the ergonomic subscale was deficient. The OPP-14 was developed by adding three additional items to the ergonomics subscale. The aim of this study is to evaluate the factor structure using confirmatory factor and Rasch analyses in healthy firefighters. Methods A sample of 261 firefighters (Mean age 42 years, 95 % male) were sampled. A confirmatory factor and Rasch analyses were used to assess the internal consistency, factor structure and other psychometric characteristics of revised OPP-14. Results The OPP-14 demonstrates sound factor structure and internal consistency in firefighters. Confirmatory factor analysis confirmed the consistency of the original 4-domain structure (CFI = 0.97, TLI = 0.96, and RMSEA = 0.053). The 5 items showing misfit initially with disordered thresholds were rescored. The four subscales satisfied Rasch expectations with well target and acceptable reliability. Conclusions The OPP-14 scale shows a promising factor structure in this sample and remediated deficits found in OPP-11. This version may be preferable for musculoskeletal concerns or work applications where ergonomic indicators are relevant.

Factor structure of the functional movement screen in marine officer candidates.

PubMed

Kazman, Josh B; Galecki, Jeffrey M; Lisman, Peter; Deuster, Patricia A; OʼConnor, Francis G

2014-03-01

Functional movement screening (FMS) is a musculoskeletal assessment that is intended to fill a gap between preparticipation examinations and performance tests. Functional movement screening consists of 7 standardized movements involving multiple muscle groups that are rated 0-3 during performance; scores are combined into a final score, which is intended to predict injury risk. This use of a sum-score in this manner assumes that the items are unidimensional and scores are internally consistent, which are measures of internal reliability. Despite research into the FMS' predictive value and interrater reliability, research has not assessed its psychometric properties. The present study is a standard psychometric analysis of the FMS and is the first to assess the internal consistency and factor structure of the FMS, using Cronbach's alpha and exploratory factor analysis (EFA). Using a cohort of 877 male and 57 female Marine officer candidates who performed the FMS, EFA of polychoric correlations with varimax rotation was conducted to explore the structure of the FMS. Tests were repeated on the original scores, which integrated feelings of pain during movement (0-3), and then on scores discounting the pain instruction and based only on the performance (1-3), to determine whether pain ratings affected the factor structure. The average FMS score was 16.7 ± 1.8. Cronbach's alpha was 0.39. Exploratory factor analysis availed 2 components accounting for 21 and 17% and consisting of separate individual movements (shoulder mobility and deep squat, respectively). Analysis on scores discounting pain showed similar results. The factor structures were not interpretable, and the low Cronbach's alpha suggests a lack of internal consistency in FMS sum scores. Results do not offer support for validity of the FMS sum score as a unidimensional construct. In the absence of additional psychometric research, caution is warranted when using the FMS sum score.

Baryonic dark matter

NASA Technical Reports Server (NTRS)

Silk, Joseph

1991-01-01

Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

Psychometric Characteristics of the Korean Version of the Satisfaction with Life Scale Adapted for Children

ERIC Educational Resources Information Center

Lim, Young-Jin

2015-01-01

The aim of this study was to examine the internal consistency reliability, test-retest reliability, factorial structure validity, and convergent validity of a Korean version of the Satisfaction With Life Scale adapted for children (K-SWLS-C). Participants consisted of 653 elementary school students (48% were male). The internal consistency of the…

Thermodynamics and kinetics of RNA tertiary structure formation in the junctionless hairpin ribozyme.

PubMed

White, Neil A; Hoogstraten, Charles G

2017-09-01

The hairpin ribozyme consists of two RNA internal loops that interact to form the catalytically active structure. This docking transition is a rare example of intermolecular formation of RNA tertiary structure without coupling to helix annealing. We have used temperature-dependent surface plasmon resonance (SPR) to characterize the thermodynamics and kinetics of RNA tertiary structure formation for the junctionless form of the ribozyme, in which loops A and B reside on separate molecules. We find docking to be strongly enthalpy-driven and to be accompanied by substantial activation barriers for association and dissociation, consistent with the structural reorganization of both internal loops upon complex formation. Comparisons with the parallel analysis of a ribozyme variant carrying a 2'-O-methyl modification at the self-cleavage site and with published data in other systems reveal a surprising diversity of thermodynamic signatures, emphasizing the delicate balance of contributions to the free energy of formation of RNA tertiary structure. Copyright © 2017 Elsevier B.V. All rights reserved.

Developing a method of fabricating microchannels using plant root structure

NASA Astrophysics Data System (ADS)

Nakashima, Shota; Tokumaru, Kazuki; Tsumori, Fujio

2018-06-01

Complicated three-dimensional (3D) microchannels are expected to be applied to a lab-on-a-chip, especially an organ-on-a-chip. There are fine microchannel networks such as blood vessels in a living organ. However, it is difficult to recreate the complicated 3D microchannels of real living structures. Plant roots have a similar structure to blood vessels. They spread radially and three-dimensionally, and become thinner as they branch. In this research, we propose a method of fabricating microchannels using a live plant root as a template to mimic a blood vessel structure. We grew a plant in ceramic slurry instead of soil. The slurry consists of ceramic powder, binder and water, so it plays a similar role to soil consisting of fine particles in water. After growing the plant, the roots inside the slurry were burned and a sintered ceramic body with channel structures was obtained by heating. We used two types of slurry with different composition ratios, and compared the internal channel structures before and after sintering.

Shell-corona microgels from double interpenetrating networks.

PubMed

Rudyak, Vladimir Yu; Gavrilov, Alexey A; Kozhunova, Elena Yu; Chertovich, Alexander V

2018-04-18

Polymer microgels with a dense outer shell offer outstanding features as universal carriers for different guest molecules. In this paper, microgels formed by an interpenetrating network comprised of collapsed and swollen subnetworks are investigated using dissipative particle dynamics (DPD) computer simulations, and it is found that such systems can form classical core-corona structures, shell-corona structures, and core-shell-corona structures, depending on the subchain length and molecular mass of the system. The core-corona structures consisting of a dense core and soft corona are formed at small microgel sizes when the subnetworks are able to effectively separate in space. The most interesting shell-corona structures consist of a soft cavity in a dense shell surrounded with a loose corona, and are found at intermediate gel sizes; the area of their existence depends on the subchain length and the corresponding mesh size. At larger molecular masses the collapsing network forms additional cores inside the soft cavity, leading to the core-shell-corona structure.

Controlled bending and folding of a bilayer structure consisting of a thin stiff film and a heat shrinkable polymer sheet

NASA Astrophysics Data System (ADS)

Cui, Jianxun; Adams, John G. M.; Zhu, Yong

2018-05-01

Bending pre-designed flat sheets into three-dimensional (3D) structures is attracting much interest, as it provides a simple approach to make 3D devices. Here we report controlled bending and folding of a bilayer structure consisting of a heat shrinkable polymer sheet and a thin stiff film (not thermally responsive). Upon heating, the prestrained polymer sheet shrinks, leading to bending or folding of the bilayer. We studied the effect of relative dimensions of the two layers on the bending behavior and demonstrated the transition from longitudinal bending to transverse bending of the bilayer strip. Transverse bending was utilized to fold origami structures, including several flat letters, a crane, and a corrugated metal sheet via Miura-ori folding. We developed a method to further control the bending orientation based on bio-inspired anisotropic bending stiffness. By bending the metal foil in different orientations, several structures were obtained, including cylindrical surfaces and left-handed/right-handed helical structures.

DEM modeling of flexible structures against granular material avalanches

NASA Astrophysics Data System (ADS)

Lambert, Stéphane; Albaba, Adel; Nicot, François; Chareyre, Bruno

2016-04-01

This article presents the numerical modeling of flexible structures intended to contain avalanches of granular and coarse material (e.g. rock slide, a debris slide). The numerical model is based on a discrete element method (YADE-Dem). The DEM modeling of both the flowing granular material and the flexible structure are detailed before presenting some results. The flowing material consists of a dry polydisperse granular material accounting for the non-sphericity of real materials. The flexible structure consists in a metallic net hanged on main cables, connected to the ground via anchors, on both sides of the channel, including dissipators. All these components were modeled as flexible beams or wires, with mechanical parameters defined from literature data. The simulation results are presented with the aim of investigating the variability of the structure response depending on different parameters related to the structure (inclination of the fence, with/without brakes, mesh size opening), but also to the channel (inclination). Results are then compared with existing recommendations in similar fields.

On the structure of the set of coincidence points

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

Arutyunov, A V; Gel'man, B D

2015-03-31

We consider the set of coincidence points for two maps between metric spaces. Cardinality, metric and topological properties of the coincidence set are studied. We obtain conditions which guarantee that this set (a) consists of at least two points; (b) consists of at least n points; (c) contains a countable subset; (d) is uncountable. The results are applied to study the structure of the double point set and the fixed point set for multivalued contractions. Bibliography: 12 titles.

Consistent Partial Least Squares Path Modeling via Regularization.

PubMed

Jung, Sunho; Park, JaeHong

2018-01-01

Partial least squares (PLS) path modeling is a component-based structural equation modeling that has been adopted in social and psychological research due to its data-analytic capability and flexibility. A recent methodological advance is consistent PLS (PLSc), designed to produce consistent estimates of path coefficients in structural models involving common factors. In practice, however, PLSc may frequently encounter multicollinearity in part because it takes a strategy of estimating path coefficients based on consistent correlations among independent latent variables. PLSc has yet no remedy for this multicollinearity problem, which can cause loss of statistical power and accuracy in parameter estimation. Thus, a ridge type of regularization is incorporated into PLSc, creating a new technique called regularized PLSc. A comprehensive simulation study is conducted to evaluate the performance of regularized PLSc as compared to its non-regularized counterpart in terms of power and accuracy. The results show that our regularized PLSc is recommended for use when serious multicollinearity is present.

Study of Improved Aluminum Materials for Vehicular Armor

DTIC Science & Technology

1977-04-07

and along cell walls. Dislocations generated during deformation cf the 17 -------------- recrystallized structure interacted with the grain...unrecrystallized (HR) 7475 plate containing dislocations within subgrains and along cell walls. Hot rolling the recrystallized structure at 750OF produced...a structure after solution heat treatment that consisted of elongated recrystallized grains containing polygonized cells . This structure developed

Development of behavioural profile in the Northern common boa (Boa imperator): Repeatable independent traits or personality?

PubMed Central

Šimková, Olga; Frýdlová, Petra; Žampachová, Barbora; Frynta, Daniel; Landová, Eva

2017-01-01

Recent studies of animal personality have focused on its proximate causation and ecological and evolutionary significance in particular, but the question of its development was largely overlooked. The attributes of personality are defined as between-individual differences in behaviour, which are consistent over time (differential consistency) and contexts (contextual generality) and both can be affected by development. We assessed several candidates for personality variables measured in various tests with different contexts over several life-stages (juveniles, older juveniles, subadults and adults) in the Northern common boa. Variables describing foraging/feeding decision and some of the defensive behaviours expressed as individual average values are highly repeatable and consistent. We found two main personality axes—one associated with foraging/feeding and the speed of decision, the other reflecting agonistic behaviour. Intensity of behaviour in the feeding context changes during development, but the level of agonistic behaviour remains the same. The juveniles and adults have a similar personality structure, but there is a period of structural change of behaviour during the second year of life (subadults). These results require a new theoretical model to explain the selection pressures resulting in this developmental pattern of personality. We also studied the proximate factors and their relationship to behavioural characteristics. Physiological parameters (heart and breath rate stress response) measured in adults clustered with variables concerning the agonistic behavioural profile, while no relationship between the juvenile/adult body size and personality concerning feeding/foraging and the agonistic behavioural profile was found. Our study suggests that it is important for studies of personality development to focus on both the structural and differential consistency, because even though behaviour is differentially consistent, the structure can change. PMID:28542424

Development of behavioural profile in the Northern common boa (Boa imperator): Repeatable independent traits or personality?

PubMed

Šimková, Olga; Frýdlová, Petra; Žampachová, Barbora; Frynta, Daniel; Landová, Eva

2017-01-01

Recent studies of animal personality have focused on its proximate causation and ecological and evolutionary significance in particular, but the question of its development was largely overlooked. The attributes of personality are defined as between-individual differences in behaviour, which are consistent over time (differential consistency) and contexts (contextual generality) and both can be affected by development. We assessed several candidates for personality variables measured in various tests with different contexts over several life-stages (juveniles, older juveniles, subadults and adults) in the Northern common boa. Variables describing foraging/feeding decision and some of the defensive behaviours expressed as individual average values are highly repeatable and consistent. We found two main personality axes-one associated with foraging/feeding and the speed of decision, the other reflecting agonistic behaviour. Intensity of behaviour in the feeding context changes during development, but the level of agonistic behaviour remains the same. The juveniles and adults have a similar personality structure, but there is a period of structural change of behaviour during the second year of life (subadults). These results require a new theoretical model to explain the selection pressures resulting in this developmental pattern of personality. We also studied the proximate factors and their relationship to behavioural characteristics. Physiological parameters (heart and breath rate stress response) measured in adults clustered with variables concerning the agonistic behavioural profile, while no relationship between the juvenile/adult body size and personality concerning feeding/foraging and the agonistic behavioural profile was found. Our study suggests that it is important for studies of personality development to focus on both the structural and differential consistency, because even though behaviour is differentially consistent, the structure can change.

i3Drefine Software for Protein 3D Structure Refinement and Its Assessment in CASP10

PubMed Central

Bhattacharya, Debswapna; Cheng, Jianlin

2013-01-01

Protein structure refinement refers to the process of improving the qualities of protein structures during structure modeling processes to bring them closer to their native states. Structure refinement has been drawing increasing attention in the community-wide Critical Assessment of techniques for Protein Structure prediction (CASP) experiments since its addition in 8th CASP experiment. During the 9th and recently concluded 10th CASP experiments, a consistent growth in number of refinement targets and participating groups has been witnessed. Yet, protein structure refinement still remains a largely unsolved problem with majority of participating groups in CASP refinement category failed to consistently improve the quality of structures issued for refinement. In order to alleviate this need, we developed a completely automated and computationally efficient protein 3D structure refinement method, i3Drefine, based on an iterative and highly convergent energy minimization algorithm with a powerful all-atom composite physics and knowledge-based force fields and hydrogen bonding (HB) network optimization technique. In the recent community-wide blind experiment, CASP10, i3Drefine (as ‘MULTICOM-CONSTRUCT’) was ranked as the best method in the server section as per the official assessment of CASP10 experiment. Here we provide the community with free access to i3Drefine software and systematically analyse the performance of i3Drefine in strict blind mode on the refinement targets issued in CASP10 refinement category and compare with other state-of-the-art refinement methods participating in CASP10. Our analysis demonstrates that i3Drefine is only fully-automated server participating in CASP10 exhibiting consistent improvement over the initial structures in both global and local structural quality metrics. Executable version of i3Drefine is freely available at http://protein.rnet.missouri.edu/i3drefine/. PMID:23894517

The Tsenkher Structure in the Gobi-Altai, Mongolia: Preliminary Results from the 2007 Expedition

NASA Astrophysics Data System (ADS)

Komatsu, G.; Ormö, J.; Bayaraa, T.; Matsui, T.; Gereltsetseg, L.; Tserendug, S.; Goto, K.; Gomez-Ortiz, D.; Demberel, S.

2008-03-01

The 3.6-3.7 km Tsenkher structure located in Mongolia was proposed to be an impact crater. Volcanic hypotheses are not ruled out, but its uplifted rim, extensive breccia deposit, and rootless structure are consistent with an impact origin.

Small-scale structure and turbulence observed in MAP/WINE)

NASA Technical Reports Server (NTRS)

Blix, T. A.

1989-01-01

During MAP/WINE small scale structure and turbulence in the mesosphere and lower thermosphere was studied in situ by rocket-borne instruments as well as from the ground by remote sensing techniques. The eight salvoes launched during the campaign resulted in a wealth of information on the dynamical structure of these regions. The experimental results are reviewed and their interpretation is discussed in terms of gravity waves and turbulence. It is shown that eddy diffusion coefficients and turbulent energy dissipation rates may be derived from the in situ measurements in a consistent manner. The observations are also shown to be consistent with the hypothesis that turbulence can be created by a process of gravity wave saturation.

Self-consistent current sheet structures in the quiet-time magnetotail

NASA Technical Reports Server (NTRS)

Holland, Daniel L.; Chen, James

1993-01-01

The structure of the quiet-time magnetotail is studied using a test particle simulation. Vlasov equilibria are obtained in the regime where v(D) = E(y) c/B(z) is much less than the ion thermal velocity and are self-consistent in that the current and magnetic field satisfy Ampere's law. Force balance between the plasma and magnetic field is satisfied everywhere. The global structure of the current sheet is found to be critically dependent on the source distribution function. The pressure tensor is nondiagonal in the current sheet with anisotropic temperature. A kinetic mechanism is proposed whereby changes in the source distribution results in a thinning of the current sheet.

Factor structure of the Psychiatric Diagnostic Screening Questionnaire (PDSQ), a screening questionnaire for DSM-IV axis I disorders.

PubMed

Sheeran, T; Zimmerman, M

2004-03-01

We examined the factor structure of the Psychiatric Diagnostic Screening Questionnaire (PDSQ), a 125-item self-report scale that screens for 15 of the most common Axis I psychiatric disorders for which patients seek treatment in outpatient settings. The sample consisted of 2440 psychiatric outpatients. Thirteen factors were extracted. Ten mapped directly onto the DSM-IV diagnosis for which they were designed and one represented suicidal ideation. The remaining two factors reflected closely related disorders: Panic Disorder/Agoraphobia, and Somatization/Hypochondriasis. A psychosis factor was not extracted. Overall, the factor structure of the PDSQ was consistent with the DSM-IV nosology upon which it was developed.

Unambiguous UML Composite Structures: The OMEGA2 Experience

NASA Astrophysics Data System (ADS)

Ober, Iulian; Dragomir, Iulia

Starting from version 2.0, UML introduced hierarchical composite structures, which are a very expressive way of defining complex software architectures, but which have a very loosely defined semantics in the standard. In this paper we propose a set of consistency rules that ensure UML composite structures are unambiguous and can be given a precise semantics. Our primary application of the static consistency rules defined in this paper is within the OMEGA UML profile [6], but these rules are general and applicable to other hierarchical component models based on the same concepts, such as MARTE GCM or SysML. The rule set has been formalized in OCL and is currently used in the OMEGA UML compiler.

REPDOSE: A database on repeated dose toxicity studies of commercial chemicals--A multifunctional tool.

PubMed

Bitsch, A; Jacobi, S; Melber, C; Wahnschaffe, U; Simetska, N; Mangelsdorf, I

2006-12-01

A database for repeated dose toxicity data has been developed. Studies were selected by data quality. Review documents or risk assessments were used to get a pre-screened selection of available valid data. The structure of the chemicals should be rather simple for well defined chemical categories. The database consists of three core data sets for each chemical: (1) structural features and physico-chemical data, (2) data on study design, (3) study results. To allow consistent queries, a high degree of standardization categories and glossaries were developed for relevant parameters. At present, the database consists of 364 chemicals investigated in 1018 studies which resulted in a total of 6002 specific effects. Standard queries have been developed, which allow analyzing the influence of structural features or PC data on LOELs, target organs and effects. Furthermore, it can be used as an expert system. First queries have shown that the database is a very valuable tool.

The social psychological costs of racial segmentation in the workplace: a study of African Americans' well-being.

PubMed

Forman, Tyrone A

2003-09-01

Although several studies have documented how social-structural constraints impair psychological functioning, few have considered how race-related structural constraints impair African Americans' psychological functioning. This study focuses on an under-studied form of race-related structural constraints: racial segmentation in the workplace. Specifically, I examine the association between perceived workplace racial segmentation, conceived and assessed from a social psychological perspective, and African Americans' psychological well-being. The magnitude and consistency of the relationship is evaluated across both a national sample and a local probability sample of African Americans. Findings across the two samples indicate a modest but consistent negative relationship between perceived racial segmentation and psychological well-being. In addition, this association remains significant after controlling for perceived discrimination as well as sociodemographic and occupational characteristics. Consistent with prior research on relative deprivation, the adverse influence of perceived racial segmentation on well-being was stronger among higher socioeconomic status African Americans than lower socioeconomic African Americans.

Low-energy electron diffraction study of potassium adsorbed on single-crystal graphite and highly oriented pyrolytic graphite

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

Ferralis, N.; Diehl, R.D.; Pussi, K.

2004-12-15

Potassium adsorption on graphite has been a model system for the understanding of the interaction of alkali metals with surfaces. The geometries of the (2x2) structure of potassium on both single-crystal graphite (SCG) and highly oriented pyrolytic graphite (HOPG) were investigated for various preparation conditions for graphite temperatures between 55 and 140 K. In all cases, the geometry was found to consist of K atoms in the hollow sites on top of the surface. The K-graphite average perpendicular spacing is 2.79{+-}0.03 A , corresponding to an average C-K distance of 3.13{+-}0.03 A , and the spacing between graphite planes ismore » consistent with the bulk spacing of 3.35 A. No evidence was observed for a sublayer of potassium. The results of dynamical LEED studies for the clean SCG and HOPG surfaces indicate that the surface structures of both are consistent with the truncated bulk structure of graphite.« less

Social Anxiety Scale for Adolescents and School Anxiety Inventory: Psychometric properties in French adolescents.

PubMed

Delgado, Beatriz; García-Fernández, José M; Martínez-Monteagudo, María C; Inglés, Cándido J; Marzo, Juan C; La Greca, Annette M; Hugon, Mandarine

2018-06-02

School and social anxiety are common problems and have a significant impact on youths' development. Nevertheless, the questionnaires to assess these anxious symptoms in French adolescents have limitations. The aim of this study is to provide a French version of the Social Anxiety Scale for Adolescents (SAS-A) and the School Anxiety Inventory (SAI), analysing their psychometric properties by the factor structure, internal consistency, and convergent validity. The SAS-A and the SAI were collectively administered in a sample of 1011 French adolescents (48.5% boys) ranging in age from 11 to 18 years. Confirmatory factor analyses replicated the previously identified correlated three-factor structure of the SAS-A and the correlated four-factor structure of the SAI. Acceptable internal consistency indexes were found for SAS-A and SAI scores. Correlations supported the convergent validity of the questionnaires' subscales. Overall, results supported the internal consistency and validity of the French versions of the SAS-A and SAI.

Comparison between cone-beam and multislice computed tomography depicting mandibular neurovascular canal structures.

PubMed

Naitoh, Munetaka; Nakahara, Kino; Suenaga, Yutaka; Gotoh, Kenichi; Kondo, Shintaro; Ariji, Eiichiro

2010-01-01

The most common diagnostic imaging modalities for cross-sectional imaging in dental implant planning are currently cone-beam computed tomography (CBCT) and multislice CT (MSCT). However, clinical differences between CBCT and MSCT in this task have not been fully clarified. In this investigation, the detection of fine anatomical structures in the mandible was assessed and compared between CBCT and MSCT images. The sample consisted of 28 patients who had undergone CBCT and MSCT. The bifid mandibular canal in the mandibular ramus, accessory mental and buccal foramina, and median and lateral lingual bony canals were observed in 2-D images, and the findings were compared between CBCT and MSCT. Four of 19 canals observed in CBCT were not observed in MSCT images. Three accessory mental foramina in 2 patients and 28 lateral lingual bony canals in 18 patients were observed consistently using the two methods. Depiction of fine anatomic features in the mandible associated with neurovascular structures is consistent between CBCT and MSCT images. Copyright 2010 Mosby, Inc. All rights reserved.

Tandem Mass Spectrometry and Ion Mobility Reveals Structural Insight into Eicosanoid Product Ion Formation

NASA Astrophysics Data System (ADS)

Di Giovanni, James P.; Barkley, Robert M.; Jones, David N. M.; Hankin, Joseph A.; Murphy, Robert C.

2018-04-01

Ion mobility measurements of product ions were used to characterize the collisional cross section (CCS) of various complex lipid [M-H]- ions using traveling wave ion mobility mass spectrometry (TWIMS). TWIMS analysis of various product ions derived after collisional activation of mono- and dihydroxy arachidonate metabolites was found to be more complex than the analysis of intact molecular ions and provided some insight into molecular mechanisms involved in product ion formation. The CCS observed for the molecular ion [M-H]- and certain product ions were consistent with a folded ion structure, the latter predicted by the proposed mechanisms of product ion formation. Unexpectedly, product ions from [M-H-H2O-CO2]- and [M-H-H2O]- displayed complex ion mobility profiles suggesting multiple mechanisms of ion formation. The [M-H-H2O]- ion from LTB4 was studied in more detail using both nitrogen and helium as the drift gas in the ion mobility cell. One population of [M-H-H2O]- product ions from LTB4 was consistent with formation of covalent ring structures, while the ions displaying a higher CCS were consistent with a more open-chain structure. Using molecular dynamics and theoretical CCS calculations, energy minimized structures of those product ions with the open-chain structures were found to have a higher CCS than a folded molecular ion structure. The measurement of product ion mobility can be an additional and unique signature of eicosanoids measured by LC-MS/MS techniques. [Figure not available: see fulltext.

Effects of different loading patterns on the trabecular bone morphology of the proximal femur using adaptive bone remodeling.

PubMed

Banijamali, S Mohammad Ali; Oftadeh, Ramin; Nazarian, Ara; Goebel, Ruben; Vaziri, Ashkan; Nayeb-Hashemi, Hamid

2015-01-01

In this study, the changes in the bone density of human femur model as a result of different loadings were investigated. The model initially consisted of a solid shell representing cortical bone encompassing a cubical network of interconnected rods representing trabecular bone. A computationally efficient program was developed that iteratively changed the structure of trabecular bone by keeping the local stress in the structure within a defined stress range. The stress was controlled by either enhancing existing beam elements or removing beams from the initial trabecular frame structure. Analyses were performed for two cases of homogenous isotropic and transversely isotropic beams.Trabecular bone structure was obtained for three load cases: walking, stair climbing and stumbling without falling. The results indicate that trabecular bone tissue material properties do not have a significant effect on the converged structure of trabecular bone. In addition, as the magnitude of the loads increase, the internal structure becomes denser in critical zones. Loading associated with the stumbling results in the highest density;whereas walking, considered as a routine daily activity, results in the least internal density in different regions. Furthermore, bone volume fraction at the critical regions of the converged structure is in good agreement with previously measured data obtained from combinations of dual X-ray absorptiometry (DXA) and computed tomography (CT). The results indicate that the converged bone architecture consisting of rods and plates are consistent with the natural bone morphology of the femur. The proposed model shows a promising means to understand the effects of different individual loading patterns on the bone density.

Tandem Mass Spectrometry and Ion Mobility Reveals Structural Insight into Eicosanoid Product Ion Formation.

PubMed

Di Giovanni, James P; Barkley, Robert M; Jones, David N M; Hankin, Joseph A; Murphy, Robert C

2018-04-23

Ion mobility measurements of product ions were used to characterize the collisional cross section (CCS) of various complex lipid [M-H] - ions using traveling wave ion mobility mass spectrometry (TWIMS). TWIMS analysis of various product ions derived after collisional activation of mono- and dihydroxy arachidonate metabolites was found to be more complex than the analysis of intact molecular ions and provided some insight into molecular mechanisms involved in product ion formation. The CCS observed for the molecular ion [M-H] - and certain product ions were consistent with a folded ion structure, the latter predicted by the proposed mechanisms of product ion formation. Unexpectedly, product ions from [M-H-H 2 O-CO 2 ] - and [M-H-H 2 O] - displayed complex ion mobility profiles suggesting multiple mechanisms of ion formation. The [M-H-H 2 O] - ion from LTB 4 was studied in more detail using both nitrogen and helium as the drift gas in the ion mobility cell. One population of [M-H-H 2 O] - product ions from LTB 4 was consistent with formation of covalent ring structures, while the ions displaying a higher CCS were consistent with a more open-chain structure. Using molecular dynamics and theoretical CCS calculations, energy minimized structures of those product ions with the open-chain structures were found to have a higher CCS than a folded molecular ion structure. The measurement of product ion mobility can be an additional and unique signature of eicosanoids measured by LC-MS/MS techniques. Graphical Abstract ᅟ.

Neutronic Reactor Structure

DOEpatents

Vernon, H. C.; Weinberg, A. M.

1961-05-30

The neutronic reactor is comprised of a core consisting of natural uranium and heavy water with a K-factor greater than unity. The core is surrounded by a reflector consisting of natural uranium and ordinary water with a Kfactor less than unity. (AEC)

NEUTRONIC REACTOR STRUCTURE

DOEpatents

Weinberg, A.M.; Vernon, H.C.

1961-05-30

A neutronic reactor is described. It has a core consisting of natural uranium and heavy water and having a K-factor greater than unity which is surrounded by a reflector consisting of natural uranium and ordinary water having a Kfactor less than unity.

Self Consistent Bathymetric Mapping From Robotic Vehicles in the Deep Ocean

DTIC Science & Technology

2005-06-01

that have been aligned in a consistent manner. Experimental results from the fully automated processing of a multibeam survey over the TAG hydrothermal structure at the Mid-Atlantic ridge are presented to validate the proposed method.

Inferring consistent functional interaction patterns from natural stimulus FMRI data

PubMed Central

Sun, Jiehuan; Hu, Xintao; Huang, Xiu; Liu, Yang; Li, Kaiming; Li, Xiang; Han, Junwei; Guo, Lei

2014-01-01

There has been increasing interest in how the human brain responds to natural stimulus such as video watching in the neuroimaging field. Along this direction, this paper presents our effort in inferring consistent and reproducible functional interaction patterns under natural stimulus of video watching among known functional brain regions identified by task-based fMRI. Then, we applied and compared four statistical approaches, including Bayesian network modeling with searching algorithms: greedy equivalence search (GES), Peter and Clark (PC) analysis, independent multiple greedy equivalence search (IMaGES), and the commonly used Granger causality analysis (GCA), to infer consistent and reproducible functional interaction patterns among these brain regions. It is interesting that a number of reliable and consistent functional interaction patterns were identified by the GES, PC and IMaGES algorithms in different participating subjects when they watched multiple video shots of the same semantic category. These interaction patterns are meaningful given current neuroscience knowledge and are reasonably reproducible across different brains and video shots. In particular, these consistent functional interaction patterns are supported by structural connections derived from diffusion tensor imaging (DTI) data, suggesting the structural underpinnings of consistent functional interactions. Our work demonstrates that specific consistent patterns of functional interactions among relevant brain regions might reflect the brain's fundamental mechanisms of online processing and comprehension of video messages. PMID:22440644

DICCCOL: Dense Individualized and Common Connectivity-Based Cortical Landmarks

PubMed Central

Zhu, Dajiang; Guo, Lei; Jiang, Xi; Zhang, Tuo; Zhang, Degang; Chen, Hanbo; Deng, Fan; Faraco, Carlos; Jin, Changfeng; Wee, Chong-Yaw; Yuan, Yixuan; Lv, Peili; Yin, Yan; Hu, Xiaolei; Duan, Lian; Hu, Xintao; Han, Junwei; Wang, Lihong; Shen, Dinggang; Miller, L Stephen

2013-01-01

Is there a common structural and functional cortical architecture that can be quantitatively encoded and precisely reproduced across individuals and populations? This question is still largely unanswered due to the vast complexity, variability, and nonlinearity of the cerebral cortex. Here, we hypothesize that the common cortical architecture can be effectively represented by group-wise consistent structural fiber connections and take a novel data-driven approach to explore the cortical architecture. We report a dense and consistent map of 358 cortical landmarks, named Dense Individualized and Common Connectivity–based Cortical Landmarks (DICCCOLs). Each DICCCOL is defined by group-wise consistent white-matter fiber connection patterns derived from diffusion tensor imaging (DTI) data. Our results have shown that these 358 landmarks are remarkably reproducible over more than one hundred human brains and possess accurate intrinsically established structural and functional cross-subject correspondences validated by large-scale functional magnetic resonance imaging data. In particular, these 358 cortical landmarks can be accurately and efficiently predicted in a new single brain with DTI data. Thus, this set of 358 DICCCOL landmarks comprehensively encodes the common structural and functional cortical architectures, providing opportunities for many applications in brain science including mapping human brain connectomes, as demonstrated in this work. PMID:22490548

Vibration and shape control of hinged light structures using electromagnetic forces

NASA Astrophysics Data System (ADS)

Matsuzaki, Yuji; Miyachi, Shigenobu; Sasaki, Toshiyuki

2003-08-01

This paper describes a new electromagnetic device for vibration control of a light-weighted deployable/retractable structure which consists of many small units connected with mechanical hinges. A typical example of such a structure is a solar cell paddle of an artificial satellite which is composed of many thin flexible blankets connected in series. Vibration and shape control of the paddle is not easy, because control force and energy do not transmit well between the blankets which are discretely connected by hinges with each other. The new device consists of a permanent magnet glued along an edge of a blanket and an electric current-conducting coil glued along an adjoining edge of another adjacent blanket. Conduction of the electric current in a magnetic field from the magnet generates an electromagnetic force on the coil. By changing the current in the coil, therefore, we may control the vibration and shape of the blankets. To confirm the effectiveness of the new device, constructing a simple paddle model consisting eight hinge- panels, we have carried out a model experiment of vibration and shape control of the paddle. In addition, a numerical simulation of vibration control of the hinge structure is performed to compare with measured data.

Development and Evaluation of the Telephone Crisis Support Skills Scale.

PubMed

Kitchingman, Taneile A; Wilson, Coralie J; Caputi, Peter; Woodward, Alan; Hunt, Tara

2015-01-01

Although telephone services continue to play an important role in the delivery of front-line crisis support, published evidence of the standardized assessment of such services does not exist to date. To describe the development of the Telephone Crisis Support Skills Scale (TCSSS), an instrument to assess workers' intentions to use recommended skills with callers, and to evaluate its factor structure and reliability. TCSSS items were mapped to a national telephone crisis support practice model. A national sample of workers (n = 210) completed the TCSSS as part of a larger online survey. Principal axis factoring was used to evaluate the structure of the instrument. Internal consistency was assessed by Cronbach's α values. A single factor accounted for more than 40% of the variance within TCSSS ratings, indicating unidimensional structure. Cronbach's α coefficients suggested adequate internal consistency. Results indicate that the TCSSS is an internally consistent, unidimensional scale, sufficiently sensitive to detect workers' skill priorities for different caller problem types. Further study is required to confirm the factor structure and reliability of the TCSSS using workers from different organizations. Following further evaluation, the TCSSS may be applied to assessing readiness for and quality of service delivery.

The structure of some cytoplasmic components of plant cells in relation to the biochemical properties of isolated particles.

PubMed

HODGE, A J; MARTIN, E M; MORTON, R K

1957-01-25

1. Electron micrographs of thin sections of material fixed with buffered osmium tetroxide have been used for comparison of the fine structure of isolated cytoplasmic particles from silver beet petioles and roots of germinating wheat with that of the cytoplasm of the intact cells. 2. Mitochondria of wheat roots have an external double membrane and poorly oriented internal double membranes. As compared with the structures seen in situ, the isolated mitochondria showed evidence of some disorganisation of the fine internal structure, probably due to osmotic effects. The possible influence of such changes on the enzymic properties of the isolated mitochondria is discussed. 3. The isolated plant microsomes are mainly spherical vesicular structures consisting of (a) an outer membrane enclosing (b) either an homogeneous slightly dense material (wheat root microsomes) or some granular dense material (silver beet microsomes) and (c) small dense particles, mostly associated with the vesicle membranes. 4. The cytoplasm of the wheat root cells does not contain any structures similar to the isolated microsomes but has a very dense reticular network, consisting of membranes with associated small dense particles, here called the endoplasmic reticulum. The observations indicate that the isolated microsomes arise mainly by rupture and transformation of the membranes of this structure. The effects of such extensive changes in the lipoprotein membranes on the enzymic activities of the endoplasmic reticulum, as studied in isolated microsomes, is discussed. 5. Meristematic wheat root cells contain structures which consist of smooth membranes with associated vacuoles and are similar to the Golgi zones of animal cells. The membranes of these zones probably contribute to the microsomal fraction under the conditions of preparation used for the enzymic and chemical studies previously reported.

THE STRUCTURE OF SOME CYTOPLASMIC COMPONENTS OF PLANT CELLS IN RELATION TO THE BIOCHEMICAL PROPERTIES OF ISOLATED PARTICLES

PubMed Central

Hodge, A. J.; Martin, E. M.; Morton, R. K.

1957-01-01

1. Electron micrographs of thin sections of material fixed with buffered osmium tetroxide have been used for comparison of the fine structure of isolated cytoplasmic particles from silver beet petioles and roots of germinating wheat with that of the cytoplasm of the intact cells. 2. Mitochondria of wheat roots have an external double membrane and poorly oriented internal double membranes. As compared with the structures seen in situ, the isolated mitochondria showed evidence of some disorganisation of the fine internal structure, probably due to osmotic effects. The possible influence of such changes on the enzymic properties of the isolated mitochondria is discussed. 3. The isolated plant microsomes are mainly spherical vesicular structures consisting of (a) an outer membrane enclosing (b) either an homogeneous slightly dense material (wheat root microsomes) or some granular dense material (silver beet microsomes) and (c) small dense particles, mostly associated with the vesicle membranes. 4. The cytoplasm of the wheat root cells does not contain any structures similar to the isolated microsomes but has a very dense reticular network, consisting of membranes with associated small dense particles, here called the endoplasmic reticulum. The observations indicate that the isolated microsomes arise mainly by rupture and transformation of the membranes of this structure. The effects of such extensive changes in the lipoprotein membranes on the enzymic activities of the endoplasmic reticulum, as studied in isolated microsomes, is discussed. 5. Meristematic wheat root cells contain structures which consist of smooth membranes with associated vacuoles and are similar to the Golgi zones of animal cells. The membranes of these zones probably contribute to the microsomal fraction under the conditions of preparation used for the enzymic and chemical studies previously reported. PMID:13416311

Structure and Regulatory Interactions of the Cytoplasmic Terminal Domains of Serotonin Transporter

PubMed Central

2014-01-01

Uptake of neurotransmitters by sodium-coupled monoamine transporters of the NSS family is required for termination of synaptic transmission. Transport is tightly regulated by protein–protein interactions involving the small cytoplasmic segments at the amino- and carboxy-terminal ends of the transporter. Although structures of homologues provide information about the transmembrane regions of these transporters, the structural arrangement of the terminal domains remains largely unknown. Here, we combined molecular modeling, biochemical, and biophysical approaches in an iterative manner to investigate the structure of the 82-residue N-terminal and 30-residue C-terminal domains of human serotonin transporter (SERT). Several secondary structures were predicted in these domains, and structural models were built using the Rosetta fragment-based methodology. One-dimensional 1H nuclear magnetic resonance and circular dichroism spectroscopy supported the presence of helical elements in the isolated SERT N-terminal domain. Moreover, introducing helix-breaking residues within those elements altered the fluorescence resonance energy transfer signal between terminal cyan fluorescent protein and yellow fluorescent protein tags attached to full-length SERT, consistent with the notion that the fold of the terminal domains is relatively well-defined. Full-length models of SERT that are consistent with these and published experimental data were generated. The resultant models predict confined loci for the terminal domains and predict that they move apart during the transport-related conformational cycle, as predicted by structures of homologues and by the “rocking bundle” hypothesis, which is consistent with spectroscopic measurements. The models also suggest the nature of binding to regulatory interaction partners. This study provides a structural context for functional and regulatory mechanisms involving SERT terminal domains. PMID:25093911

From Death Metal to R&B? Consistency of Music Preferences among Dutch Adolescents and Young Adults

ERIC Educational Resources Information Center

Mulder, Juul; Ter Bogt, Tom F. M.; Raaijmakers, Quinten A. W.; Gabhainn, Saoirse Nic; Sikkema, Paul

2010-01-01

The structure of music preferences has been investigated extensively. However, development of music preferences in terms of consistency of music taste is as yet understudied. In this study, intra-individual consistency of music taste was assessed among Dutch adolescents and young adults over three points in time in a 21-month period. An…

Characterization of the multilayered shell of a limpet, Lottia kogamogai (Mollusca: Patellogastropoda), using SEM-EBSD and FIB-TEM techniques.

PubMed

Suzuki, Michio; Kameda, Jun; Sasaki, Takenori; Saruwatari, Kazuko; Nagasawa, Hiromichi; Kogure, Toshihiro

2010-08-01

The microstructure and its crystallographic aspect of the shell of a limpet, Lottiakogamogai, have been investigated, as the first step to clarify the mechanism of shell formation in limpet. The shell consists of five distinct layers stacked along the shell thickness direction. Transmission electron microscopy (TEM) with the focused ion beam (FIB) sample preparation technique was primarily adopted, as well as scanning electron microscopy (SEM) with electron back-scattered diffraction (EBSD). The five layers were termed as M+3, M+2, M+1, M, M-1 from the outside to the inside in previous works, where M means myostracum. The outmost M+3 layer consists of calcite with a "mosaic" structure; granular submicron sub-grains with small-angle grain boundaries often accompanying dislocation arrays. M+2 layer consists of flat prismatic aragonite crystals with a leaf-like cross section, stacked obliquely to the shell surface. It looks that the prismatic crystals are surrounded by organic sheets, forming a compartment structure. M+1 and M-1 layers adopt a crossed lamellar structure consisting of aragonite flat prisms with rectangular cross section. M layer has a prismatic structure of aragonite perpendicular to the shell surface and with irregular shaped cross sections. Distinct organic sheets were not observed between the crystals in M+1, M and M-1 layers. The {110} twins are common in all aragonite M+2, M+1, M and M-1 layers, with the twin boundaries parallel to the prisms. These results for the microstructure of each layer should be considered in the discussion of the formation mechanism of the limpet shell structure. Copyright 2010 Elsevier Inc. All rights reserved.

Structural evolution of the Chugach-Prince William terrane at the hinge of the orocline in Prince William Sound, and implications for ore deposits: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1992

USGS Publications Warehouse

Haeussler, Peter J.; Nelson, Steven W.

1993-01-01

The Chugach-Prince William terrane is a Mesozoic through Tertiary accretionary complex that lies along coastal southern and southeastern Alaska. In Prince William Sound, the regional structural fabric bends about 90°, forming an orocline. Rocks at the hinge of the orocline consist of turbidites, conglomerate, and minor volcanic rocks and limestone. The structural geology in the hinge region defines a number of domains (each >15 km2) consisting of kilometer-scale tight folds. Adjacent domains may have up to a 90° difference in the strike of bedding and trend of fold axes. Four granite to tonalitic or gabbro plutons are dated or inferred to be about 35 Main age, and all were emplaced after regional folding. Base-metal sulfide mineral occurrences, barren quartz veins, and strikeslip late faults locally cut the plutons and generally strike north-south. The mineral occurrences often have a dendritic network of quartz veinlets adjacent to the mineralized zone and brecciated wall rock within the zone. Oroclinal bending, in the style of bending a bar, is consistent with the origin of the complicated domainal geometry of the structures. The Contact fault, thought by some workers to juxtapose two parts of the accretionary prism, truncates one of these 35-Ma plutons with strike-slip offset, but previous reverse motion cannot be ruled out. A magmatic source for the ore-forming fluids is consistent with the structural and mineralogical data. The north-south orientation of mineralized zones suggests that east-west extension occurred possibly during release of fluids from the plutons, which locally hydrofractured the wall rocks and allowed migration of ore-forming fluids along preexisting fractures.

The possible importance of synchrotron/inverse Compton losses to explain fast MM-wave and hard X-ray emission of a solar event

NASA Technical Reports Server (NTRS)

Correia, E.; Kaufmann, P.; Costa, J. E. R.; Vaz, A. M. Z.; Dennis, B. R.

1986-01-01

The solar burst of 21 May 1984 presented a number of unique features. The time profile consisted of seven major structures (seconds), with a turnover frequency or approx. 90 GHz, well correlated in time to hard X-ray emission. Each structure consisted of multiple fast pulses (.1 seconds), which were analyzed in detail. A proportionality between the repetition rate of the pulses and the burst fluxes at 90 GHz and or approx. 100 keV hard X-rays, and an inverse proportionality between repetition rates and hard X-rays power law indices have been found. A synchrotron/inverse Compton model has been applied to explain the emission of the fast burst structures, which appear to be possible for the first three or four structures.

The possible importance of synchrotron/inverse Compton losses to explain fast mm-wave and hard X-ray emission of a solar event

NASA Technical Reports Server (NTRS)

Correia, E.; Kaufmann, P.; Costa, J. E. R.; Zodivaz, A. M.; Dennis, B. R.

1986-01-01

The solar burst of 21 May 1984, presented a number of unique features. The time profile consisted of seven major structures (seconds), with a turnover frequency of greater than or approximately 90 GHz, well correlated in time to hard X-ray emission. Each structure consisted of multiple fast pulses (0.1 seconds), which were analyzed in detail. A proportionality between the repetition rate of the pulses and the burst fluxes at 90 GHz and greater than or approximately 100 keV hard X-rays, and an inverse proportionality between repetition rates and hard X-ray power law indices were found. A synchrotron/inverse Compton model was applied to explain the emission of the fast burst structures, which appear to be possible for the first three or four structures.

Dynamic Structure of a Molecular Liquid S0.5Cl0.5: Ab initio Molecular-Dynamics Simulations

NASA Astrophysics Data System (ADS)

Ohmura, Satoshi; Shimakura, Hironori; Kawakita, Yukinobu; Shimojo, Fuyuki; Yao, Makoto

2013-07-01

The static and dynamic structures of a molecular liquid S0.5Cl0.5 consisting of Cl--S--S--Cl (S2Cl2) type molecules are studied by means of ab initio molecular dynamics simulations. Both the calculated static and dynamic structure factors are in good agreement with experimental results. The dynamic structures are discussed based on van-Hove distinct correlation functions, molecular translational mean-square displacements (TMSD) and rotational mean-square displacements (RMSD). In the TMSD and RMSD, there are ballistic and diffusive regimes in the sub-picosecond and picosecond time regions, respectively. These time scales are consistent with the decay time observed experimentally. The interaction between molecules in the liquid is also discussed in comparison with that in another liquid chalcogen--halogen system Se0.5Cl0.5.

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.

The Structure-Mapping Engine: Algorithm and Examples.

ERIC Educational Resources Information Center

Falkenhainer, Brian; And Others

This description of the Structure-Mapping Engine (SME), a flexible, cognitive simulation program for studying analogical processing which is based on Gentner's Structure-Mapping theory of analogy, points out that the SME provides a "tool kit" for constructing matching algorithms consistent with this theory. This report provides: (1) a…

Investigating the Theoretical Structure of the DAS-II Core Battery at School Age Using Bayesian Structural Equation Modeling

ERIC Educational Resources Information Center

Dombrowski, Stefan C.; Golay, Philippe; McGill, Ryan J.; Canivez, Gary L.

2018-01-01

Bayesian structural equation modeling (BSEM) was used to investigate the latent structure of the Differential Ability Scales-Second Edition core battery using the standardization sample normative data for ages 7-17. Results revealed plausibility of a three-factor model, consistent with publisher theory, expressed as either a higher-order (HO) or a…

Structure of the orthorhombic Al13Co4(100) surface using LEED, STM, and ab initio studies

NASA Astrophysics Data System (ADS)

Shin, Heekeun; Pussi, K.; Gaudry, É.; Ledieu, J.; Fournée, V.; Alarcón Villaseca, S.; Dubois, J.-M.; Grin, Yu.; Gille, P.; Moritz, W.; Diehl, R. D.

2011-08-01

In a combined scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and density functional theory (DFT) study of the surface of Al13Co4(100), all techniques have found that after annealing to 1165 K, the surface structure is consistent with a dense Al-rich plane with surface Co atom depletion. Various structure models were considered, and in the LEED study, the best agreement was found with a model that consists of Al-rich terminating planes with no Co atoms, and otherwise a structure similar to the bulk puckered layers. This structure was also found to be stable in the DFT study. The best-fit structural parameters are presented for the two domains of this structure, which contain bipentagons that can be related to the pentagonal bipyramidal structures in the bulk, plus additional glue atoms between them. These domains are not strictly related to each other by symmetry, as they have different surface relaxations. The STM study found significant differences in the surfaces of samples grown by different methods and is able to explain a different interpretation made in an earlier study.

Clustering of 3D-Structure Similarity Based Network of Secondary Metabolites Reveals Their Relationships with Biological Activities.

PubMed

Ohtana, Yuki; Abdullah, Azian Azamimi; Altaf-Ul-Amin, Md; Huang, Ming; Ono, Naoaki; Sato, Tetsuo; Sugiura, Tadao; Horai, Hisayuki; Nakamura, Yukiko; Morita Hirai, Aki; Lange, Klaus W; Kibinge, Nelson K; Katsuragi, Tetsuo; Shirai, Tsuyoshi; Kanaya, Shigehiko

2014-12-01

Developing database systems connecting diverse species based on omics is the most important theme in big data biology. To attain this purpose, we have developed KNApSAcK Family Databases, which are utilized in a number of researches in metabolomics. In the present study, we have developed a network-based approach to analyze relationships between 3D structure and biological activity of metabolites consisting of four steps as follows: construction of a network of metabolites based on structural similarity (Step 1), classification of metabolites into structure groups (Step 2), assessment of statistically significant relations between structure groups and biological activities (Step 3), and 2-dimensional clustering of the constructed data matrix based on statistically significant relations between structure groups and biological activities (Step 4). Applying this method to a data set consisting of 2072 secondary metabolites and 140 biological activities reported in KNApSAcK Metabolite Activity DB, we obtained 983 statistically significant structure group-biological activity pairs. As a whole, we systematically analyzed the relationship between 3D-chemical structures of metabolites and biological activities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural phase transitions in GaAs to 108 GPa

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

Weir, S.T.; Vohra, Y.K.; Vanderborgh, C.A.

1989-01-15

The III-V compound GaAs was studied using energy-dispersive x-ray diffraction with a synchro- tron source up to a pressure of 108 GPa. When the pressure was increased to 16.6 GPa, the GaAs sample transformed from the zinc-blende structure to an orthorhombic structure (GaAs(II)), space group Pmm2, consisting of a primitive orthorhombic lattice with a basis of (0,0,0) and (0,(1/2,..cap alpha..), where ..cap alpha.. = 0.35. Upon a further increase of pressure to 24 +- 1 GPa, GaAs(II) transformed to another orthorhombic structure (GaAs(III)), space group Imm2, consisting of a body-centered orthorhombic lattice with a basis of (0,0,0) and (0, (1/2,..delta..),more » where ..delta.. is 0.425 at 28.1 GPa. With increasing pressure, ..delta.. approached (1/2 and the GaAs(III) structure gradually assumed the symmetry of the simple hexagonal structure. The transition to the simple hexagonal structure (GaAs(IV)) was completed in the vicinity of 60--80 GPa. The structure remains simple hexagonal up to at least 108 GPa, the highest pressure reached in this study.« less

Study on embedding fiber Bragg grating sensor into the 3D printing structure for health monitoring

NASA Astrophysics Data System (ADS)

Li, Ruiya; Tan, Yuegang; Zhou, Zude; Fang, Liang; Chen, Yiyang

2016-10-01

3D printing technology is a rapidly developing manufacturing technology, which is known as a core technology in the third industrial revolution. With the continuous improvement of the application of 3D printing products, the health monitoring of the 3D printing structure is particularly important. Fiber Bragg grating (FBG) sensing technology is a new type of optical sensing technology with unique advantages comparing to traditional sensing technology, and it has great application prospects in structural health monitoring. In this paper, the FBG sensors embedded in the internal structure of the 3D printing were used to monitor the static and dynamic strain variation of 3D printing structure during loading process. The theoretical result and experimental result has good consistency and the characteristic frequency detected by FBG sensor is consistent with the testing results of traditional accelerator in the dynamic experiment. The results of this paper preliminary validate that FBG embedded in the 3D printing structure can effectively detecting the static and dynamic stain change of the 3D printing structure, which provide some guidance for the health monitoring of 3D printing structure.

A review of structural patterns and melting processes in the Archean craton of West Greenland: Evidence for crustal growth at convergent plate margins as opposed to non-uniformitarian models

NASA Astrophysics Data System (ADS)

Polat, Ali; Wang, Lu; Appel, Peter W. U.

2015-11-01

The Archean craton of West Greenland consists of many fault-bounded Eoarchean to Neoarchean tectonic terranes (crustal blocks). These tectonic terranes are composed mainly of tonalite-trondhjemite-granodiorite (TTG) gneisses, granitic gneisses, metavolcanic-dominated supracrustal belts, layered anorthositic complexes, and late- to post-tectonic granites. Rock assemblages and geochemical signatures in these terranes suggest that they represent fragments of dismembered oceanic island arcs, consisting mainly of TTG plutons, tholeiitic to calc-alkaline basalts, boninites, picrites, and cumulate layers of ultramafic rocks, gabbros, leucogabbros and anorthosites, with minor sedimentary rocks. The structural characteristics of the terrane boundaries are consistent with the assembly of these island arcs through modern style of horizontal tectonics, suggesting that the Archean craton of West Greenland grew at convergent plate margins. Several supracrustal belts that occur at or near the terrane boundaries are interpreted as relict accretionary prisms. The terranes display fold and thrust structures and contain numerous 10 cm to 20 m wide bifurcating, ductile shear zones that are characterized by a variety of structures including transposed and redistributed isoclinal folds. Geometrically these structures are similar to those occurring on regional scales, suggesting that the Archean craton of West Greenland can be interpreted as a continental scale accretionary complex, such as the Paleozoic Altaids. Melting of metavolcanic rocks during tectonic thickening in the arcs played an important role in the generation of TTGs. Non-uniformitarian models proposed for the origin of Archean terranes have no analogs in the geologic record and are inconsistent with structural, lithological, petrological and geochemical data collected from Archean terranes over the last four decades. The style of deformation and generation of felsic rocks on outcrop scales in the Archean craton of West Greenland and the Mesozoic Sulu orogenic belt of eastern China are similar, consistent with the formation of Archean continental crust by subduction zone processes.

Nightside Structure of the Venusian Ionosphere

NASA Astrophysics Data System (ADS)

Ledvina, S. A.; Brecht, S. H.

2017-12-01

The Pioneer Venus Orbiter, PVO, was the first mission to detect large-scale structure in the nightside region of Venus. This structure is often referred to as "tail rays." Since this discovery, there has been continuous discussion as to the cause of the structure. There have been theoretical attempts to explain the structure but no definitive determination of the mechanism. Typically, the wavelengths of the structure were not always consistent with the theory. Three-dimensional hybrid simulations are reported that produce structure on the nightside of Venus. The structure seems consistent with the data. This paper will present the results of the simulations as well as a variety of numerical tests that offer some insight into the mechanism driving the development of the structure. The tests reveal that the ambipolar electric fields as produced by the gradient of the electron pressure seems to be the root cause of the structure. It will be shown that different realizations of the neutral wind modify the structure. The hybrid simulations are three dimensional with neutral winds included in the simulations. The resolution of the simulation is 50 km/cell and lower. The spherical grid used in the simulations to handle chemistry and collisions has a resolution of 5 km radially and under 50 km in the angular directions. It is these high resolution simulations that produce the structure to be discussed in this paper.

Two classes of ODE models with switch-like behavior

PubMed Central

Just, Winfried; Korb, Mason; Elbert, Ben; Young, Todd

2013-01-01

In cases where the same real-world system can be modeled both by an ODE system ⅅ and a Boolean system 𝔹, it is of interest to identify conditions under which the two systems will be consistent, that is, will make qualitatively equivalent predictions. In this note we introduce two broad classes of relatively simple models that provide a convenient framework for studying such questions. In contrast to the widely known class of Glass networks, the right-hand sides of our ODEs are Lipschitz-continuous. We prove that if 𝔹 has certain structures, consistency between ⅅ and 𝔹 is implied by sufficient separation of time scales in one class of our models. Namely, if the trajectories of 𝔹 are “one-stepping” then we prove a strong form of consistency and if 𝔹 has a certain monotonicity property then there is a weaker consistency between ⅅ and 𝔹. These results appear to point to more general structure properties that favor consistency between ODE and Boolean models. PMID:24244061

[Factor analysis and internal consistency of pedagogical practices questionnaire among health care teachers].

PubMed

Pérez V, Cristhian; Vaccarezza G, Giulietta; Aguilar A, César; Coloma N, Katherine; Salgado F, Horacio; Baquedano R, Marjorie; Chavarría R, Carla; Bastías V, Nancy

2016-06-01

Teaching practice is one of the most complex topics of the training process in medicine and other health care careers. The Teaching Practices Questionnaire (TPQ) evaluates teaching skills. To assess the factor structure and internal consistency of the Spanish version of the TPP among health care teachers. The TPQ was answered by 315 university teachers from 13 of the 15 administrative Chilean regions, who were selected through a non-probabilistic volunteer sampling. The internal consistency of TPP factors was calculated and the correlation between them was analyzed. Six factors were identified: Student-centered teaching, Teaching planning, Assessment process, Dialogue relationship, Teacher-centered teaching and Use of technological resources. They had Cronbach alphas ranging from 0.60 to 0.85. The factorial structure of TPQ differentiates the most important functions of teaching. It also shows a theoretical consistency and a practical relevance to perform a diagnosis and continuous evaluation of teaching practices. Additionally, it has an adequate internal consistency. Thus, TPQ is valid and reliable to evaluate pedagogical practices in health care careers.

Does GaH5 exist?

NASA Astrophysics Data System (ADS)

Speakman, Lucas D.; Turney, Justin M.; Schaefer, Henry F.

2005-11-01

The existence or nonexistence of GaH5 has been widely discussed [N. M. Mitzel, Angew. Chem. Int. Ed. 42, 3856 (2003)]. Seven possible structures for gallium pentahydride have been systematically investigated using ab initio electronic structure theory. Structures and vibrational frequencies have been determined employing self-consistent field, coupled cluster including all single and double excitations (CCSD), and CCSD with perturbative triples levels of theory, with at least three correlation-consistent polarized-valence-(cc-pVXZ and aug-cc-pVXZ) type basis sets. The X˜A'1 state for GaH5 is predicted to be weakly bound complex 1 between gallane and molecular hydrogen, with Cs symmetry. The dissociation energy corresponding to GaH5→GaH3+H2 is predicted to be De=2.05kcalmol-1. The H-H stretching fundamental is predicted to be v =4060cm-1, compared to the tentatively assigned experimental feature of Wang and Andrews [J. Phys. Chem. A 107, 11371 (2003)] at 4087cm-1. A second Cs structure 2 with nearly equal energy is predicted to be a transition state, corresponding to a 90° rotation of the H2 bond. Thus the rotation of the hydrogen molecule is essentially free. However, hydrogen scrambling through the C2v structure 3 seems unlikely, as the activation barrier for scrambling is at least 30kcalmol-1 higher in energy than that for the dissociation of GaH5 to GaH3 and H2. Two additional structures consisting of GaH3 with a dihydrogen bond perpendicular to gallane (C3v structure 4) and an in-plane dihydrogen bond [Cs(III) structure 5] were also examined. A C3v symmetry second-order saddle point has nearly the same energy as the GaH3+H2 dissociation limit, while the Cs(III) structure 5 is a transition structure to the C3v structure. The C4v structure 6 and the D3h structure 7 are much higher in energy than GaH3+H2 by 88 and 103kcalmol-1, respectively.

Gravity investigations of the Chesapeake Bay impact structure

USGS Publications Warehouse

Plescia, J.B.; Daniels, D.L.; Shah, A.K.

2009-01-01

The Chesapeake Bay impact structure is a complex impact crater, ??85 km in diameter, buried beneath postimpact sediments. Its main structural elements include a central uplift of crystalline bedrock, a surrounding inner crater filled with impact debris, and an annular faulted margin composed of block-faulted sediments. The gravity anomaly is consistent with that of a complex impact consisting of a central positive anomaly over the central uplift and an annular negative anomaly over the inner crater. An anomaly is not recognized as being associated with the faulted margin or the outer edge of the structure. Densities from the Eyreville drill core and modeling indicate a density contrast of ??0.3-0.6 g cm-3 between crystalline basement and the material that fills the inner crater (e.g., Exmore breccia and suevite). This density contrast is somewhat higher than for other impact structures, but it is a function of the manner in which the crater fill was deposited (as a marine resurge deposit). Modeling of the gravity data is consistent with a depth to basement of ??1600 m at the site of Eyreville drill hole and 800 m at the central uplift. Both depths are greater than the depth at which crystalline rocks were encountered in the cores, suggesting that the cored material is highly fractured para-allochthonous rock. ?? 2009 The Geological Society of America.

Improving Heat Transfer at the Bottom of Vials for Consistent Freeze Drying with Unidirectional Structured Ice.

PubMed

Rosa, Mónica; Tiago, João M; Singh, Satish K; Geraldes, Vítor; Rodrigues, Miguel A

2016-10-01

The quality of lyophilized products is dependent of the ice structure formed during the freezing step. Herein, we evaluate the importance of the air gap at the bottom of lyophilization vials for consistent nucleation, ice structure, and cake appearance. The bottom of lyophilization vials was modified by attaching a rectified aluminum disc with an adhesive material. Freezing was studied for normal and converted vials, with different volumes of solution, varying initial solution temperature (from 5°C to 20°C) and shelf temperature (from -20°C to -40°C). The impact of the air gap on the overall heat transfer was interpreted with the assistance of a computational fluid dynamics model. Converted vials caused nucleation at the bottom and decreased the nucleation time up to one order of magnitude. The formation of ice crystals unidirectionally structured from bottom to top lead to a honeycomb-structured cake after lyophilization of a solution with 4% mannitol. The primary drying time was reduced by approximately 35%. Converted vials that were frozen radially instead of bottom-up showed similar improvements compared with normal vials but very poor cake quality. Overall, the curvature of the bottom of glass vials presents a considerable threat to consistency by delaying nucleation and causing radial ice growth. Rectifying the vials bottom with an adhesive material revealed to be a relatively simple alternative to overcome this inconsistency.

The Eastwide forest inventory data base: users manual.

Treesearch

Mark H. Hansen; Thomas Frieswyk; Joseph F. Glover; John F. Kelly

1992-01-01

Describes the standard Eastwide Data base (EWDB) structure. This computer file structure was developed to provide consistent data on the forest resources of the Eastern United States. These data files are available to the public.

Toughened and corrosion- and wear-resistant composite structures and fabrication methods thereof

DOEpatents

Seals, Roland D.; Ripley, Edward B.; Hallman, Russell L.

2017-06-20

Composite structures having a reinforced material interjoined with a substrate, wherein the reinforced material comprises a compound selected from the group consisting of titanium monoboride, titanium diboride, and combinations thereof.

A random-walk/giant-loop model for interphase chromosomes.

PubMed Central

Sachs, R K; van den Engh, G; Trask, B; Yokota, H; Hearst, J E

1995-01-01

Fluorescence in situ hybridization data on distances between defined genomic sequences are used to construct a quantitative model for the overall geometric structure of a human chromosome. We suggest that the large-scale geometry during the G0/G1 part of the cell cycle may consist of flexible chromatin loops, averaging approximately 3 million bp, with a random-walk backbone. A fully explicit, three-parametric polymer model of this random-walk/giant-loop structure can account well for the data. More general models consistent with the data are briefly discussed. PMID:7708711

Weak low-frequency electromagnetic oscillations in water.

PubMed

Liboff, A R; Poggi, Claudio; Pratesi, Piero

2017-01-01

Recent observations of low-frequency electromagnetic oscillations in water suggest an inductive structural component. Accordingly, we assume a helical basis enabling us to model water as an LC tuned oscillator. A proposed tetrahedral structure consisting of three water molecules and one hydronium ion is incorporated into the Boerdijk-Coxeter tetrahelix to form long water chains that are shown to have resonance frequencies consistent with observation. This model also serves to explain separately reported claims of ion cyclotron resonance of hydronium ions, in that the tetrahelix provides a built-in path for helical proton-hopping.

A "good practice" approach to the quality and consistency of morphological examination of the internal head structures of the term rabbit fetus.

PubMed

French, Julian M

2014-07-01

Variation in the interpretation of the regulatory guidelines has resulted in a diversity of techniques employed to examine the internal structures of the foetal rabbit head. Examination of the foetal rabbit brain, using a single transverse section as the sole technique, is considered not to be sufficiently thorough to be regarded as an adequate examination method. It is not compliant with published EPA and OECD guidelines covering required examination of the internal head structures, nor is it considered to conform to the spirit of the safety assessment required by the ICH guideline. Fixation of approximately half of the heads in each litter to allow the examination of multiple transverse sections enables the major structures within the head to be assessed effectively. This method is compliant with current guidelines, represents "good practice" and should be consistently adopted for the examination of the internal head structures of the term rabbit foetus. Copyright © 2014 Elsevier Inc. All rights reserved.

Autotransporter structure reveals intra-barrel cleavage followed by conformational changes.

PubMed

Barnard, Travis J; Dautin, Nathalie; Lukacik, Petra; Bernstein, Harris D; Buchanan, Susan K

2007-12-01

Autotransporters are virulence factors produced by Gram-negative bacteria. They consist of two domains, an N-terminal 'passenger' domain and a C-terminal beta-domain. beta-domains form beta-barrel structures in the outer membrane while passenger domains are translocated into the extracellular space. In some autotransporters, the two domains are separated by proteolytic cleavage. Using X-ray crystallography, we solved the 2.7-A structure of the post-cleavage state of the beta-domain of EspP, an autotransporter produced by Escherichia coli strain O157:H7. The structure consists of a 12-stranded beta-barrel with the passenger domain-beta-domain cleavage junction located inside the barrel pore, approximately midway between the extracellular and periplasmic surfaces of the outer membrane. The structure reveals an unprecedented intra-barrel cleavage mechanism and suggests that two conformational changes occur in the beta-domain after cleavage, one conferring increased stability on the beta-domain and another restricting access to the barrel pore.

Ensemble clustering in visual working memory biases location memories and reduces the Weber noise of relative positions.

PubMed

Lew, Timothy F; Vul, Edward

2015-01-01

People seem to compute the ensemble statistics of objects and use this information to support the recall of individual objects in visual working memory. However, there are many different ways that hierarchical structure might be encoded. We examined the format of structured memories by asking subjects to recall the locations of objects arranged in different spatial clustering structures. Consistent with previous investigations of structured visual memory, subjects recalled objects biased toward the center of their clusters. Subjects also recalled locations more accurately when they were arranged in fewer clusters containing more objects, suggesting that subjects used the clustering structure of objects to aid recall. Furthermore, subjects had more difficulty recalling larger relative distances, consistent with subjects encoding the positions of objects relative to clusters and recalling them with magnitude-proportional (Weber) noise. Our results suggest that clustering improved the fidelity of recall by biasing the recall of locations toward cluster centers to compensate for uncertainty and by reducing the magnitude of encoded relative distances.

Selective Mutism Questionnaire: measurement structure and validity.

PubMed

Letamendi, Andrea M; Chavira, Denise A; Hitchcock, Carla A; Roesch, Scott C; Shipon-Blum, Elisa; Stein, Murray B

2008-10-01

To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire (SMQ). Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children-Parent Version; SM severity was assessed using the 17-item SMQ; and behavioral and affective symptoms were assessed using the Child Behavior Checklist. An exploratory factor analysis was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm exploratory factor analysis results. Internal consistency, construct validity, and incremental validity were also examined. The exploratory factor analysis yielded a 13-item solution consisting of three factors: social situations outside of school, school situations, and home and family situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity was also well supported. Measure structure findings are consistent with the three-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomena beyond other child anxiety measures.

An interactive graphics system to facilitate finite element structural analysis

NASA Technical Reports Server (NTRS)

Burk, R. C.; Held, F. H.

1973-01-01

The characteristics of an interactive graphics systems to facilitate the finite element method of structural analysis are described. The finite element model analysis consists of three phases: (1) preprocessing (model generation), (2) problem solution, and (3) postprocessing (interpretation of results). The advantages of interactive graphics to finite element structural analysis are defined.

26 CFR 1.593-11 - Qualifying real property loan and nonqualifying loan defined.

Code of Federal Regulations, 2014 CFR

2014-04-01

... consisting of a structure or structures containing, in the aggregate, no more than four family units..., apartment house, office building, hospital, shopping center, warehouse, garage, or other similar permanent structure), provided that the value of such building is substantial in relation to the value of such land...

26 CFR 1.593-11 - Qualifying real property loan and nonqualifying loan defined.

Code of Federal Regulations, 2013 CFR

2013-04-01

... consisting of a structure or structures containing, in the aggregate, no more than four family units..., apartment house, office building, hospital, shopping center, warehouse, garage, or other similar permanent structure), provided that the value of such building is substantial in relation to the value of such land...

26 CFR 1.593-11 - Qualifying real property loan and nonqualifying loan defined.

Code of Federal Regulations, 2011 CFR

2011-04-01

... consisting of a structure or structures containing, in the aggregate, no more than four family units..., apartment house, office building, hospital, shopping center, warehouse, garage, or other similar permanent structure), provided that the value of such building is substantial in relation to the value of such land...

26 CFR 1.593-11 - Qualifying real property loan and nonqualifying loan defined.

Code of Federal Regulations, 2010 CFR

2010-04-01

... consisting of a structure or structures containing, in the aggregate, no more than four family units..., apartment house, office building, hospital, shopping center, warehouse, garage, or other similar permanent structure), provided that the value of such building is substantial in relation to the value of such land...

26 CFR 1.593-11 - Qualifying real property loan and nonqualifying loan defined.

Code of Federal Regulations, 2012 CFR

2012-04-01

... consisting of a structure or structures containing, in the aggregate, no more than four family units..., apartment house, office building, hospital, shopping center, warehouse, garage, or other similar permanent structure), provided that the value of such building is substantial in relation to the value of such land...

The Disruptive Effect of Lysozyme on the Bacterial Cell Wall Explored by an "In-Silico" Structural Outlook

ERIC Educational Resources Information Center

Primo, Emiliano D.; Otero, Lisandro H.; Ruiz, Francisco; Klinke, Sebastián; Giordano, Walter

2018-01-01

The bacterial cell wall, a structural unit of peptidoglycan polymer comprised of glycan strands consisting of a repeating disaccharide motif [N-acetylglucosamine (NAG) and N-acetylmuramylpentapeptide (NAM pentapeptide)], encases bacteria and provides structural integrity and protection. Lysozymes are enzymes that break down the bacterial cell wall…

Spatial Cognition Support for Exploring the Design Mechanics of Building Structures

ERIC Educational Resources Information Center

Rudy, Margit; Hauck, Richard

2008-01-01

A web-based tool for visualizing the simulated structural behavior of building models was developed to support the teaching of structural design to architecture and engineering students by activating their spatial cognition capabilities. The main didactic issues involved establishing a consistent and complete three-dimensional vocabulary (3D)…

Factor Structure of the Psychotherapy Supervisor Development Scale

ERIC Educational Resources Information Center

Barnes, Kristin L.; Moon, Simon M.

2006-01-01

The goodness of fit of 3 models of factor structure of the Psychotherapy Supervisor Development Scale (PSDS; C. E. Watkins, L. J. Schneider, J. Haynes, & R. Nieberding, 1995) were examined using a sample of counseling supervisors. The results indicated that the factor structure of the PSDS was largely consistent with the original 4-factor…

Investigating Effects of Invasive Species on Plant Community Structure

ERIC Educational Resources Information Center

Franklin, Wilfred

2008-01-01

In this article, the author presents a field study project that explores factors influencing forest community structure and lifts the veil off of "plant blindness." This ecological study consists of three laboratories: (1) preliminary field trip to the study site; (2) plant survey; and (3) analyzing plant community structure with descriptive…

Phonological and Phonetic Evidence for Trochaic Metrical Structure in Standard Chinese

ERIC Educational Resources Information Center

Sui, Yanyan

2013-01-01

Native speakers of Standard Chinese have significant difficulty judging the prominence of words with tones in a consistent way. How then can metrical structure in the language be diagnosed? This study approaches the question by investigating how metrical structure interacts with other aspects of phonology, especially tone; what foot type is used…

Design of Hybrid Solid Polymer Electrolytes: Structure and Properties

NASA Technical Reports Server (NTRS)

Bronstein, Lyudmila M.; Karlinsey, Robert L.; Ritter, Kyle; Joo, Chan Gyu; Stein, Barry; Zwanziger, Josef W.

2003-01-01

This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.

Continental-scale assessment of genetic diversity and population structure in quaking aspen (Populus tremuloides)

Treesearch

Colin M. Callahan; Carol A. Rowe; Ronald J. Ryel; John D. Shaw; Michael D. Madritch; Karen E. Mock

2013-01-01

Aspen populations in the south-western portion of the range are consistent with expectations for a historically stable edge, with low within-population diversity, significant geographical population structuring, and little evidence of northward expansion. Structuring within the southwestern cluster may result from distinct gene pools separated during the Pleistocene...

Creating Masterpieces: How Course Structures and Routines Enable Student Performance

ERIC Educational Resources Information Center

Dean, Kathy Lund; Fornaciari, Charles J.

2014-01-01

Over a five-year period, we made a persistent observation: Course structures and routines, such as assignment parameters, student group process rules, and grading schemes were being consistently ignored. As a result, we got distracted by correcting these structural issues and were spending less time on student assignment performance. In this…

Aviation Structural Mechanic, Second Class, 2-13. Military Curriculum Materials for Vocational and Technical Education.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This self-paced, individualized course, adapted from military curriculum materials for use in vocational and technical education, teaches students the skills needed to become aviation structural mechanics (second class). The course materials consist of five pamphlets covering the structural maintenance and repair of aircraft. The first pamphlet…

Multidisciplinary Analysis of a Hypersonic Engine

NASA Technical Reports Server (NTRS)

Suresh, Ambady; Stewart, Mark

2003-01-01

The objective is to develop high fidelity tools that can influence ISTAR design In particular, tools for coupling Fluid-Thermal-Structural simulations RBCC/TBCC designers carefully balance aerodynamic, thermal, weight, & structural considerations; consistent multidisciplinary solutions reveal details (at modest cost) At Scram mode design point, simulations give details of inlet & combustor performance, thermal loads, structural deflections.

School and Classroom Goal Structures: Effects on Affective Responses in Physical Education

ERIC Educational Resources Information Center

Barkoukis, Vassilis; Koidou, Eirini; Tsorbatzoudis, Haralambos; Grouios, George

2012-01-01

The current study examined the relative impact of school and classroom goal structures on students' affective responses and the mediating role of motivation. The sample of the study consisted of 368 high school students, who completed measures of school and classroom goal structures, motivational regulations in physical education, boredom, and…

Teacher Observation of Classroom Adaptation--Checklist: Development and Factor Structure

ERIC Educational Resources Information Center

Koth, Christine W.; Bradshaw, Catherine P.; Leaf, Philip J.

2009-01-01

Two studies examined the validity and factor structure of the Teacher Observation of Classroom Adaptation-Checklist, an instrument used to evaluate school-based programs. The checklist is a cost-effective alternative to the original interview format, and the factor structure is consistent across gender, race, age, and time of administration.…

The structures of native celluloses, and the origin of their variability

Treesearch

R. H. Atalla

1999-01-01

The structures of native celluloses have traditionally been presented in terms of two-domain models consisting of crystalline and non-crystalline fractions. Such models have been of little help in advancing understanding of enzyme-substrate interactions. In this report we first address issues that complicate characterization of the structure of native celluloses...

Semiconductor-Insulator-Semiconductor Diode Consisting of Monolayer MoS2, h-BN, and GaN Heterostructure.

PubMed

Jeong, Hyun; Bang, Seungho; Oh, Hye Min; Jeong, Hyeon Jun; An, Sung-Jin; Han, Gang Hee; Kim, Hyun; Kim, Ki Kang; Park, Jin Cheol; Lee, Young Hee; Lerondel, Gilles; Jeong, Mun Seok

2015-10-27

We propose a semiconductor-insulator-semiconductor (SIS) heterojunction diode consisting of monolayer (1-L) MoS2, hexagonal boron nitride (h-BN), and epitaxial p-GaN that can be applied to high-performance nanoscale optoelectronics. The layered materials of 1-L MoS2 and h-BN, grown by chemical vapor deposition, were vertically stacked by a wet-transfer method on a p-GaN layer. The final structure was verified by confocal photoluminescence and Raman spectroscopy. Current-voltage (I-V) measurements were conducted to compare the device performance with that of a more classical p-n structure. In both structures (the p-n and SIS heterojunction diode), clear current-rectifying characteristics were observed. In particular, a current and threshold voltage were obtained for the SIS structure that was higher compared to that of the p-n structure. This indicated that tunneling is the predominant carrier transport mechanism. In addition, the photoresponse of the SIS structure induced by the illumination of visible light was observed by photocurrent measurements.

Post-Flight Estimation of Motion of Space Structures: Part 2

NASA Technical Reports Server (NTRS)

Brugarolas, Paul; Breckenridge, William

2008-01-01

A computer program related to the one described in the immediately preceding article estimates the relative position of two space structures that are hinged to each other. The input to the program consists of time-series data on distances, measured by two range finders at different positions on one structure, to a corner-cube retroreflector on the other structure. Given a Cartesian (x,y,z) coordinate system and the known x coordinate of the retroreflector relative to the y,z plane that contains the range finders, the program estimates the y and z coordinates of the retroreflector. The estimation process involves solving for the y,z coordinates of the intersection between (1) the y,z plane that contains the retroreflector and (2) spheres, centered on the range finders, having radii equal to the measured distances. In general, there are two such solutions and the program chooses the one consistent with the design of the structures. The program implements a Kalman filter. The output of the program is a time series of estimates of the relative position of the structures.

Nanoparticles of CdCl2 with closed cage structures

NASA Astrophysics Data System (ADS)

Popovitz-Biro, R.; Twersky, A.; Hacohen, Y. Rosenfeld; Tenne, R.

2000-11-01

Nanoparticles of various layered compounds having a closed cage or nanotubular structure, designated also inorganic fullerene-like (IF) materials, have been reported in the past. In this work IF-CdCl2 nanoparticles were synthesized by electron beam irradiation of the source powder leading to its recrystallization into closed nanoparticles with a nonhollow core. This process created polyhedral nanoparticles with hexagonal or elongated rectangular characters. The analysis also shows that, while the source (dried) powder is orthorhombic cadmium chloride monohydrate, the crystallized IF cage consists of the anhydrous 3R polytype which is not stable as bulk material in ambient atmosphere. Consistent with previous observations, this study shows that the seamless structure of the IF materials can stabilize phases, which are otherwise unstable in ambient conditions.

Global Electricity Trade Network: Structures and Implications

PubMed Central

Ji, Ling; Jia, Xiaoping; Chiu, Anthony S. F.; Xu, Ming

2016-01-01

Nations increasingly trade electricity, and understanding the structure of the global power grid can help identify nations that are critical for its reliability. This study examines the global grid as a network with nations as nodes and international electricity trade as links. We analyze the structure of the global electricity trade network and find that the network consists of four sub-networks, and provide a detailed analysis of the largest network, Eurasia. Russia, China, Ukraine, and Azerbaijan have high betweenness measures in the Eurasian sub-network, indicating the degrees of centrality of the positions they hold. The analysis reveals that the Eurasian sub-network consists of seven communities based on the network structure. We find that the communities do not fully align with geographical proximity, and that the present international electricity trade in the Eurasian sub-network causes an approximately 11 million additional tons of CO2 emissions. PMID:27504825

Global Electricity Trade Network: Structures and Implications.

PubMed

Ji, Ling; Jia, Xiaoping; Chiu, Anthony S F; Xu, Ming

2016-01-01

Nations increasingly trade electricity, and understanding the structure of the global power grid can help identify nations that are critical for its reliability. This study examines the global grid as a network with nations as nodes and international electricity trade as links. We analyze the structure of the global electricity trade network and find that the network consists of four sub-networks, and provide a detailed analysis of the largest network, Eurasia. Russia, China, Ukraine, and Azerbaijan have high betweenness measures in the Eurasian sub-network, indicating the degrees of centrality of the positions they hold. The analysis reveals that the Eurasian sub-network consists of seven communities based on the network structure. We find that the communities do not fully align with geographical proximity, and that the present international electricity trade in the Eurasian sub-network causes an approximately 11 million additional tons of CO2 emissions.

Compact 3D photonic crystals sensing platform with 45 degree angle polished fibers

NASA Astrophysics Data System (ADS)

Guo, Yuqing; Chen, Lu; Zhu, Jiali; Ni, Haibin; Xia, Wei; Wang, Ming

2017-07-01

Three dimensional photonic crystals are a kind of promising sensing materials in biology and chemistry. A compact structure, consists of planner colloidal crystals and 45 degree angle polished fiber, is proposed as a platform for accurate, fast, reliable three dimensional photonic crystals sensing in practice. This structure show advantages in compact size for integration and it is ease for large scale manufacture. Reflectivity of the 45 degree angle polished surface with and without a layer of Ag film are simulated by FDTD simulation. Refractive index sensing properties as well as mode distribution of this structure consists of both polystyrene opal and silica inverse opal film is investigated, and an experimental demonstration of silica inverse opal film is performed, which shows a sensitivity of 733 nm/RIU. Different kinds of three dimensional photonic crystals can also be applied in this structure for particular purpose.

The structure of Escherichia coli signal recognition particle revealed by scanning transmission electron microscopy.

PubMed

Mainprize, Iain L; Beniac, Daniel R; Falkovskaia, Elena; Cleverley, Robert M; Gierasch, Lila M; Ottensmeyer, F Peter; Andrews, David W

2006-12-01

Structural studies on various domains of the ribonucleoprotein signal recognition particle (SRP) have not converged on a single complete structure of bacterial SRP consistent with the biochemistry of the particle. We obtained a three-dimensional structure for Escherichia coli SRP by cryoscanning transmission electron microscopy and mapped the internal RNA by electron spectroscopic imaging. Crystallographic data were fit into the SRP reconstruction, and although the resulting model differed from previous models, they could be rationalized by movement through an interdomain linker of Ffh, the protein component of SRP. Fluorescence resonance energy transfer experiments determined interdomain distances that were consistent with our model of SRP. Docking our model onto the bacterial ribosome suggests a mechanism for signal recognition involving interdomain movement of Ffh into and out of the nascent chain exit site and suggests how SRP could interact and/or compete with the ribosome-bound chaperone, trigger factor, for a nascent chain during translation.

Implementing the Hospital Emergency Incident Command System: an integrated delivery system's experience.

PubMed

Zane, Richard D; Prestipino, Ann L

2004-01-01

Hospital disaster manuals and response plans often lack formal command structure; instead, they rely on the presence of key individuals who are familiar with hospital operations, or who are in leadership positions during routine, day-to-day operations. Although this structure occasionally may prove to be successful, it is unreliable, as this leadership may be unavailable at the time of the crisis, and may not be sustainable during a prolonged event. The Hospital Emergency Incident Command System (HEICS) provides a command structure that does not rely on specific individuals, is flexible and expandable, and is ubiquitous in the fire service, emergency medical services, military, and police agencies, thus allowing for ease of communication during event management. A descriptive report of the implementation of the HEICS throughout a large healthcare network is reviewed. Implementation of the HEICS provides a consistent command structure for hospitals that enables consistency and commonality with other hospitals and disaster response entities.

A three-dimensional actuated origami-inspired transformable metamaterial with multiple degrees of freedom

NASA Astrophysics Data System (ADS)

Overvelde, Johannes T. B.; de Jong, Twan A.; Shevchenko, Yanina; Becerra, Sergio A.; Whitesides, George M.; Weaver, James C.; Hoberman, Chuck; Bertoldi, Katia

2016-03-01

Reconfigurable devices, whose shape can be drastically altered, are central to expandable shelters, deployable space structures, reversible encapsulation systems and medical tools and robots. All these applications require structures whose shape can be actively controlled, both for deployment and to conform to the surrounding environment. While most current reconfigurable designs are application specific, here we present a mechanical metamaterial with tunable shape, volume and stiffness. Our approach exploits a simple modular origami-like design consisting of rigid faces and hinges, which are connected to form a periodic structure consisting of extruded cubes. We show both analytically and experimentally that the transformable metamaterial has three degrees of freedom, which can be actively deformed into numerous specific shapes through embedded actuation. The proposed metamaterial can be used to realize transformable structures with arbitrary architectures, highlighting a robust strategy for the design of reconfigurable devices over a wide range of length scales.

General mechanism of two-state protein folding kinetics.

PubMed

Rollins, Geoffrey C; Dill, Ken A

2014-08-13

We describe here a general model of the kinetic mechanism of protein folding. In the Foldon Funnel Model, proteins fold in units of secondary structures, which form sequentially along the folding pathway, stabilized by tertiary interactions. The model predicts that the free energy landscape has a volcano shape, rather than a simple funnel, that folding is two-state (single-exponential) when secondary structures are intrinsically unstable, and that each structure along the folding path is a transition state for the previous structure. It shows how sequential pathways are consistent with multiple stochastic routes on funnel landscapes, and it gives good agreement with the 9 order of magnitude dependence of folding rates on protein size for a set of 93 proteins, at the same time it is consistent with the near independence of folding equilibrium constant on size. This model gives estimates of folding rates of proteomes, leading to a median folding time in Escherichia coli of about 5 s.

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

Abugideiri, F.; Kelland, M.A.; Poli, R.

Cp*MoH[sub 5](PMe[sub 3]) has been prepared from Cp*MoCl[sub 2](PMe[sub 3]) and LiAlH[sub 4]. The compound is analogous to the previously reported Cp*WH[sub 5](PMe[sub 3]) and CpWH[sub 5](PMe[sub 3]) (Green, M.L.H.; Parkin, G.J. Chem. Soc., Chem. Commun. 1984, 1467. Schrock, R. R.; et al. Organometallics 1986, 5, 1681) for which structural assignments were not made. A single sharp [sup 1]H-NMR resonance is observed for the five hydrides down to 183 K, consistent with either a static symmetric structure or a highly fluxional structure, either classical or nonclassical. The measured minimum longtudinal relaxation time, T[sub 1], is quite long (780 ms atmore » 400 MHz and 230 K) and consistent with a classical structure based on the pentagonal bipyramid which gives rise to a substantially anisotropic moment of inertia. 14 refs., 1 tab.« less

Two-dimensional sup 1 H NMR studies on HPr protein from Staphylococcus aureus: Complete sequential assignments and secondary structure

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

Kalbitzer, H.R.; Neidig, K.P.; Hengstenberg, W.

1991-11-19

Complete sequence-specific assignments of the {sup 1}H NMR spectrum of HPr protein from Staphylococcus aureus were obtained by two-dimensional NMR methods. Important secondary structure elements that can be derived from the observed nuclear Overhauser effects are a large antiparallel {beta}-pleated sheet consisting of four strands, A, B, C, D, a segment S{sub AB} consisting of an extended region around the active-center histidine (His-15) and an {alpha}-helix, a half-turn between strands B and C, a segment S{sub CD} which shows no typical secondary structure, and the {alpha}-helical, C-terminal segment S{sub term}. These general structural features are similar to those found earliermore » in HPr proteins from different microorganisms such as Escherichia coli, Bacillus subtilis, and Streptococcus faecalis.« less

Scanning Electron Microscopy Investigation of a Sample Depth Profile Through the Martian Meteorite Nakhla

NASA Technical Reports Server (NTRS)

Toporski, Jan; Steele, Andrew; Westall, Frances; McKay, David S.

2000-01-01

The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

Unmasking the masked Universe: the 2M++ catalogue through Bayesian eyes

NASA Astrophysics Data System (ADS)

Lavaux, Guilhem; Jasche, Jens

2016-01-01

This work describes a full Bayesian analysis of the Nearby Universe as traced by galaxies of the 2M++ survey. The analysis is run in two sequential steps. The first step self-consistently derives the luminosity-dependent galaxy biases, the power spectrum of matter fluctuations and matter density fields within a Gaussian statistic approximation. The second step makes a detailed analysis of the three-dimensional large-scale structures, assuming a fixed bias model and a fixed cosmology. This second step allows for the reconstruction of both the final density field and the initial conditions at z = 1000 assuming a fixed bias model. From these, we derive fields that self-consistently extrapolate the observed large-scale structures. We give two examples of these extrapolation and their utility for the detection of structures: the visibility of the Sloan Great Wall, and the detection and characterization of the Local Void using DIVA, a Lagrangian based technique to classify structures.

The Discovery of an Evolving Dust Scattered X-ray Halo Around GRB 031203

NASA Technical Reports Server (NTRS)

Vaughan, S.; Willingale, R.; OBrien, P. T.; Osborne, J. P.; Reeves, J. N.; Levan, A. J.; Watson, M. G.; Tedds, J. A.; Watson, D.; Santos-Lleo, M.

2003-01-01

We report the first detection of a time-dependent, dust-scattered X-ray halo around a gamma-ray burst. GRB3 031203 was observed by XMM-Newton starting six hours after the burst. The halo appeared as concentric ring-like structures centered on the GRB location. The radii of these structures increased with time as t(sup 1/2), consistent with small-angle X-ray scattering caused by a large column of dust along the line of sight to a cosmologically distant GRB. The rings are due to dust concentrated in two distinct slabs in the Galaxy located at distances of 880 and 1390 pc, consistent with known Galactic features. The halo brightness implies an initial soft X-ray pulse consistent with the observed GRB.

The Structure of Character Strengths: Variable- and Person-Centered Approaches

PubMed Central

Najderska, Małgorzata; Cieciuch, Jan

2018-01-01

This article examines the structure of character strengths (Peterson and Seligman, 2004) following both variable-centered and person-centered approaches. We used the International Personality Item Pool-Values in Action (IPIP-VIA) questionnaire. The IPIP-VIA measures 24 character strengths and consists of 213 direct and reversed items. The present study was conducted in a heterogeneous group of N = 908 Poles (aged 18–78, M = 28.58). It was part of a validation project of a Polish version of the IPIP-VIA questionnaire. The variable-centered approach was used to examine the structure of character strengths on both the scale and item levels. The scale-level results indicated a four-factor structure that can be interpreted based on four of the five personality traits from the Big Five theory (excluding neuroticism). The item-level analysis suggested a slightly different and limited set of character strengths (17 not 24). After conducting a second-order analysis, a four-factor structure emerged, and three of the factors could be interpreted as being consistent with the scale-level factors. Three character strength profiles were found using the person-centered approach. Two of them were consistent with alpha and beta personality metatraits. The structure of character strengths can be described by using categories from the Five Factor Model of personality and metatraits. They form factors similar to some personality traits and occur in similar constellations as metatraits. The main contributions of this paper are: (1) the validation of IPIP-VIA conducted in variable-centered approach in a new research group (Poles) using a different measurement instrument; (2) introducing the person-centered approach to the study of the structure of character strengths. PMID:29515482

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

NASA Astrophysics Data System (ADS)

Song, Jingru; Fan, Cuncai; Ma, Hansong; Wei, Yueguang

2015-06-01

In the present research, hierarchical structure observation and mechanical property characterization for a type of biomaterial are carried out. The investigated biomaterial is Hyriopsis cumingii, a typical limnetic shell, which consists of two different structural layers, a prismatic "pillar" structure and a nacreous "brick and mortar" structure. The prismatic layer looks like a "pillar forest" with variation-section pillars sized on the order of several tens of microns. The nacreous material looks like a "brick wall" with bricks sized on the order of several microns. Both pillars and bricks are composed of nanoparticles. The mechanical properties of the hierarchical biomaterial are measured by using the nanoindentation test. Hardness and modulus are measured for both the nacre layer and the prismatic layer, respectively. The nanoindentation size effects for the hierarchical structural materials are investigated experimentally. The results show that the prismatic nanostructured material has a higher stiffness and hardness than the nacre nanostructured material. In addition, the nanoindentation size effects for the hierarchical structural materials are described theoretically, by using the trans-scale mechanics theory considering both strain gradient effect and the surface/interface effect. The modeling results are consistent with experimental ones.

Consistent global structures of complex RNA states through multidimensional chemical mapping

PubMed Central

Cheng, Clarence Yu; Chou, Fang-Chieh; Kladwang, Wipapat; Tian, Siqi; Cordero, Pablo; Das, Rhiju

2015-01-01

Accelerating discoveries of non-coding RNA (ncRNA) in myriad biological processes pose major challenges to structural and functional analysis. Despite progress in secondary structure modeling, high-throughput methods have generally failed to determine ncRNA tertiary structures, even at the 1-nm resolution that enables visualization of how helices and functional motifs are positioned in three dimensions. We report that integrating a new method called MOHCA-seq (Multiplexed •OH Cleavage Analysis with paired-end sequencing) with mutate-and-map secondary structure inference guides Rosetta 3D modeling to consistent 1-nm accuracy for intricately folded ncRNAs with lengths up to 188 nucleotides, including a blind RNA-puzzle challenge, the lariat-capping ribozyme. This multidimensional chemical mapping (MCM) pipeline resolves unexpected tertiary proximities for cyclic-di-GMP, glycine, and adenosylcobalamin riboswitch aptamers without their ligands and a loose structure for the recently discovered human HoxA9D internal ribosome entry site regulon. MCM offers a sequencing-based route to uncovering ncRNA 3D structure, applicable to functionally important but potentially heterogeneous states. DOI: http://dx.doi.org/10.7554/eLife.07600.001 PMID:26035425

Consistent Partial Least Squares Path Modeling via Regularization

PubMed Central

Jung, Sunho; Park, JaeHong

2018-01-01

Partial least squares (PLS) path modeling is a component-based structural equation modeling that has been adopted in social and psychological research due to its data-analytic capability and flexibility. A recent methodological advance is consistent PLS (PLSc), designed to produce consistent estimates of path coefficients in structural models involving common factors. In practice, however, PLSc may frequently encounter multicollinearity in part because it takes a strategy of estimating path coefficients based on consistent correlations among independent latent variables. PLSc has yet no remedy for this multicollinearity problem, which can cause loss of statistical power and accuracy in parameter estimation. Thus, a ridge type of regularization is incorporated into PLSc, creating a new technique called regularized PLSc. A comprehensive simulation study is conducted to evaluate the performance of regularized PLSc as compared to its non-regularized counterpart in terms of power and accuracy. The results show that our regularized PLSc is recommended for use when serious multicollinearity is present. PMID:29515491

Nanoscale structure in AgSbTe2 determined by diffuse elastic neutron scattering

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

Specht, Eliot D; Ma, Jie; Delaire, Olivier A

2015-01-01

Diffuse elastic neutron scattering measurements confirm that AgSbTe2 has a hierarchical structure, with defects on length scales from nanometers to microns. While scattering from mesoscale structure is consistent with previously-proposed structures in which Ag and Sb order on a NaCl lattice, more diffuse scattering from nanoscale structure suggests a structural rearrangement in which hexagonal layers form a combination of (ABC), (ABA), and (AAB) stacking sequences. The AgCrSe2 structure is the best-fitting model for the local atomic arrangements.

Oxygen Reduction Reaction on Platinum-Terminated “Onion-structured” Alloy Catalysts

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

Herron, Jeffrey A.; Jiao, Jiao; Hahn, Konstanze

Using periodic, self-consistent density functional theory (GGA-PW91) calculations, a series of onion-structured metal alloys have been investigated for their catalytic performance towards the oxygen reduction reaction (ORR). The onion-structures consist of a varying number of atomic layers of one or two metals each, pseudomorphically deposited on top of one another to form the overall structure. All catalysts studied feature a Pt overlayer, and often consist of at least one Pd layer below the surface. Three distinct ORR mechanisms were analyzed on the close-packed facets of all the structures considered. These mechanisms include a direct route of O2 dissociation and twomore » hydrogen-assisted routes of O–O bond-breaking in peroxyl (OOH) and in hydrogen peroxide (HOOH) intermediates. A thermochemical analysis of the elementary steps provides information on the operating potential, and thereby energy efficiency of each electrocatalyst. A Sabatier analysis of catalytic activity based on thermochemistry of proton/electron transfer steps and activation energy barrier for O–O bond-breaking steps leads to a “volcano” relation between the surfaces’ activity and the binding energy of O. Several of the onion-structured alloys studied here show promise for achieving energy efficiency higher than that of Pt, by being active at potentials higher than the operating potential of Pt. Furthermore, some have at least as good activity as pure Pt at that operating potential. Thus, a number of the onion-structured alloys studied here are promising as cathode electrocatalysts in proton exchange membrane fuel cells.« less

Diel variations in the assemblage structure and foraging ecology of larval and 0+ year juvenile fishes in a man-made floodplain waterbody.

PubMed

Tewson, L H; Cowx, I G; Nunn, A D

2016-04-01

This study investigated diel variations in zooplankton composition and abundance, and the species composition, density, size structure, feeding activity, diet composition and prey selection of larval and 0+ year juvenile fishes in the littoral of a man-made floodplain waterbody over five 24 h periods within a 57 day period. There was a significant difference in the species composition of diurnal and nocturnal catches, with most species consistently peaking in abundance either during daylight or at night, reflecting their main activity period. There were no consistent diel patterns in assemblage structure or the abundance of some species, however, most likely, respectively, due to the phenology of fish hatching and ontogenetic shifts in diel behaviour or habitat use. There were few clear diel patterns in the diet composition or prey selection of larval and 0+ year juvenile roach Rutilus rutilus and perch Perca fluviatilis, with most taxa consistently selected or avoided irrespective of the time of day or night, and no obvious shift between planktonic and benthic food sources, but dietary overlap suggested that interspecific interactions were probably strongest at night. It is essential that sampling programmes account for the diel ecology of the target species, as diurnal surveys alone could produce inaccurate assessments of resource use. The relative lack of consistent diel patterns in this study suggests that multiple 24 h surveys are required in late spring and early summer to provide accurate assessments of 0+ year fish assemblage structure and foraging ecology. © 2016 The Fisheries Society of the British Isles.

Nanostructured microtubes based on TiO2 doped by Zr and Hf oxides with the anatase structure

NASA Astrophysics Data System (ADS)

Zheleznov, VV; Voit, EI; Sushkov, YV; Sarin, SA; Kuryavyi, VG; Opra, DP; Gnedenkov, SV; Sinebryukhov, SL; Sokolov, AA

2016-01-01

The nanostructured microtubes based on TiO2 have been prepared on the carbon fiber template using the sol-gel method. The microtubes consist of nanoparticles of metal oxides: TiO2/ZrO2 and TiO2/HfO2. The dependence of microtubes morphology and nanoparticles structure on the synthesis conditions has been studied using the methods of SEM, SAXS, and Raman spectroscopy. It has been demonstrated that at the stoichiometric ratio of up to 0.04 for Zr/Ti and up to 0.06 for Hf/Ti microtubes consist of uniform nanoparticles with the anatase structure. Along with further increase of the dopants content in the microtubes composition, nanoparticles acquire the core-shell structure. It has been suggested that nanoparticles have a core composed of the solid solutions Ti1-xZrxO2 or Ti1-xHfxO2 and a shell consisting of zirconium or hafnium titanate. The fabricated Zr- and Hf-doped TiO2 materials were investigated in view of their possible use as anode materials for Li-ion batteries. Charge- discharge measurements showed that the doped samples manifested significantly higher reversibility in comparison with the undoped TiO2. The method opens new prospects in synthesis of nanostructured materials for Li-ion batteries application.

Synchronous firing patterns of induced pluripotent stem cell-derived cortical neurons depend on the network structure consisting of excitatory and inhibitory neurons.

PubMed

Iida, Shoko; Shimba, Kenta; Sakai, Koji; Kotani, Kiyoshi; Jimbo, Yasuhiko

2018-06-18

The balance between glutamate-mediated excitation and GABA-mediated inhibition is critical to cortical functioning. However, the contribution of network structure consisting of the both neurons to cortical functioning has not been elucidated. We aimed to evaluate the relationship between the network structure and functional activity patterns in vitro. We used mouse induced pluripotent stem cells (iPSCs) to construct three types of neuronal populations; excitatory-rich (Exc), inhibitory-rich (Inh), and control (Cont). Then, we analyzed the activity patterns of these neuronal populations using microelectrode arrays (MEAs). Inhibitory synaptic densities differed between the three types of iPSC-derived neuronal populations, and the neurons showed spontaneously synchronized bursting activity with functional maturation for one month. Moreover, different firing patterns were observed between the three populations; Exc demonstrated the highest firing rates, including frequent, long, and dominant bursts. In contrast, Inh demonstrated the lowest firing rates and the least dominant bursts. Synchronized bursts were enhanced by disinhibition via GABA A receptor blockade. The present study, using iPSC-derived neurons and MEAs, for the first time show that synchronized bursting of cortical networks in vitro depends on the network structure consisting of excitatory and inhibitory neurons. Copyright © 2018 Elsevier Inc. All rights reserved.

Cosmic structure and dynamics of the local Universe

NASA Astrophysics Data System (ADS)

Kitaura, Francisco-Shu; Erdoǧdu, Pirin; Nuza, Sebastián. E.; Khalatyan, Arman; Angulo, Raul E.; Hoffman, Yehuda; Gottlöber, Stefan

2012-11-01

We present a cosmography analysis of the local Universe based on the recently released Two-Micron All-Sky Redshift Survey catalogue. Our method is based on a Bayesian Networks Machine Learning algorithm (the KIGEN-code) which self-consistently samples the initial density fluctuations compatible with the observed galaxy distribution and a structure formation model given by second-order Lagrangian perturbation theory (2LPT). From the initial conditions we obtain an ensemble of reconstructed density and peculiar velocity fields which characterize the local cosmic structure with high accuracy unveiling non-linear structures like filaments and voids in detail. Coherent redshift-space distortions are consistently corrected within 2LPT. From the ensemble of cross-correlations between the reconstructions and the galaxy field and the variance of the recovered density fields, we find that our method is extremely accurate up to k˜ 1 h Mpc-1 and still yields reliable results down to scales of about 3-4 h-1 Mpc. The motion of the Local Group we obtain within ˜80 h-1 Mpc (vLG = 522 ± 86 km s-1, lLG = 291° ± 16°, bLG = 34° ± 8°) is in good agreement with measurements derived from the cosmic microwave background and from direct observations of peculiar motions and is consistent with the predictions of ΛCDM.

Lunar troilite: Crystallography

USGS Publications Warehouse

Evans, H.T.

1970-01-01

Fine, euhedral crystals of troilite from lunar sample 10050 show a hexagonal habit consistent with the high-temperature NiAs-type structure. Complete three-dimensional counter intensity data have been measured and used to confirm and refine Bertaut's proposed low-temperature crystal structure.

Structural and functional properties of hemoglobins from unicellular organisms as revealed by resonance Raman spectroscopy.

PubMed

Egawa, Tsuyoshi; Yeh, Syun-Ru

2005-01-01

Hemoglobins have been discovered in organisms from virtually all kingdoms. Their presence in unicellular organisms suggests that the gene for hemoglobin is very ancient and that the hemoglobins must have functions other than oxygen transport, in view of the fact that O2 delivery is a diffusion-controlled process in these organisms. Based on sequence alignment, three groups of hemoglobins have been characterized in unicellular organisms. The group-one hemoglobins, termed truncated hemoglobins, consist of proteins with 110-140 amino acid residues and a novel two-over-two alpha-helical sandwich motif. The group-two hemoglobins, termed flavohemoglobins, consist of a hemoglobin domain, with a classical three-over-three alpha-helical sandwich motif, and a flavin-containing reductase domain that is covalently attached to it. The group-three hemoglobins consist of myoglobin-like proteins that have high sequence homology and structural similarity to the hemoglobin domain of flavohemoglobins. In this review, recent resonance Raman studies of each group of these proteins are presented. Their implications are discussed in the context of the structural and functional properties of these novel hemoglobins.

Characterization of structural defects in SnSe2 thin films grown by molecular beam epitaxy on GaAs (111)B substrates

NASA Astrophysics Data System (ADS)

Tracy, Brian D.; Li, Xiang; Liu, Xinyu; Furdyna, Jacek; Dobrowolska, Margaret; Smith, David J.

2016-11-01

Tin selenide thin films have been grown by molecular beam epitaxy on GaAs (111)B substrates at a growth temperature of 150 °C, and a microstructural study has been carried out, primarily using the technique of transmission electron microscopy. The Se:Sn flux ratio during growth was systematically varied and found to have a strong impact on the resultant crystal structure and quality. Low flux ratios (Se:Sn=3:1) led to defective films consisting primarily of SnSe, whereas high flux ratios (Se:Sn>10:1) gave higher quality, single-phase SnSe2. The structure of the monoselenide films was found to be consistent with the Space Group Pnma with the epitaxial growth relationship of [011]SnSe// [ 1 1 bar 0 ] GaAs, while the diselenide films were consistent with the Space Group P 3 bar m1 , and had the epitaxial growth relationship [ 2 1 bar 1 bar 0 ]SnSe2// [ 1 1 bar 0 ] GaAs.

Internal Structure and Partial Invariance across Gender in the Spanish Version of the Reasoning Test Battery.

PubMed

Elosua, Paula; Mujika, Josu

2015-10-13

The Reasoning Test Battery (BPR) is an instrument built on theories of the hierarchical organization of cognitive abilities and therefore consists of different tasks related with abstract, numerical, verbal, practical, spatial and mechanical reasoning. It was originally created in Belgium and later adapted to Portuguese. There are three forms of the battery consisting of different items and scales which cover an age range from 9 to 22. This paper focuses on the adaptation of the BPR to Spanish, and analyzes different aspects of its internal structure: (a) exploratory item factor analysis was applied to assess the presence of a dominant factor for each partial scale; (b) the general underlined model was evaluated through confirmatory factor analysis, and (c) factorial invariance across gender was studied. The sample consisted of 2624 Spanish students. The results concluded the presence of a general factor beyond the scales, with equivalent values for men and women, and gender differences in the factorial structure which affect the numerical reasoning, abstract reasoning and mechanical reasoning scales.

QSPR for predicting chloroform formation in drinking water disinfection.

PubMed

Luilo, G B; Cabaniss, S E

2011-01-01

Chlorination is the most widely used technique for water disinfection, but may lead to the formation of chloroform (trichloromethane; TCM) and other by-products. This article reports the first quantitative structure-property relationship (QSPR) for predicting the formation of TCM in chlorinated drinking water. Model compounds (n = 117) drawn from 10 literature sources were divided into training data (n = 90, analysed by five-way leave-many-out internal cross-validation) and external validation data (n = 27). QSPR internal cross-validation had Q² = 0.94 and root mean square error (RMSE) of 0.09 moles TCM per mole compound, consistent with external validation Q2 of 0.94 and RMSE of 0.08 moles TCM per mole compound, and met criteria for high predictive power and robustness. In contrast, log TCM QSPR performed poorly and did not meet the criteria for predictive power. The QSPR predictions were consistent with experimental values for TCM formation from tannic acid and for model fulvic acid structures. The descriptors used are consistent with a relatively small number of important TCM precursor structures based upon 1,3-dicarbonyls or 1,3-diphenols.

Structural anomalies in undoped Gallium Arsenide observed in high resolution diffraction imaging with monochromatic synchrotron radiation

NASA Technical Reports Server (NTRS)

Steiner, B.; Kuriyama, M.; Dobbyn, R. C.; Laor, U.; Larson, D.; Brown, M.

1988-01-01

Novel, streak-like disruption features restricted to the plane of diffraction have recently been observed in images obtained by synchrotron radiation diffraction from undoped, semi-insulating gallium arsenide crystals. These features were identified as ensembles of very thin platelets or interfaces lying in (110) planes, and a structural model consisting of antiphase domain boundaries was proposed. We report here the other principal features observed in high resolution monochromatic synchrotron radiation diffraction images: (quasi) cellular structure; linear, very low-angle subgrain boundaries in (110) directions, and surface stripes in a (110) direction. In addition, we report systematic differences in the acceptance angle for images involving various diffraction vectors. When these observations are considered together, a unifying picture emerges. The presence of ensembles of thin (110) antiphase platelet regions or boundaries is generally consistent not only with the streak-like diffraction features but with the other features reported here as well. For the formation of such regions we propose two mechanisms, operating in parallel, that appear to be consistent with the various defect features observed by a variety of techniques.

Structural anomalies in undoped gallium arsenide observed in high-resolution diffraction imaging with monochromatic synchrotron radiation

NASA Technical Reports Server (NTRS)

Steiner, B.; Kuriyama, M.; Dobbyn, R. C.; Laor, U.; Larson, D.

1989-01-01

Novel, streak-like disruption features restricted to the plane of diffraction have recently been observed in images obtained by synchrotron radiation diffraction from undoped, semi-insulating gallium arsenide crystals. These features were identified as ensembles of very thin platelets or interfaces lying in (110) planes, and a structural model consisting of antiphase domain boundaries was proposed. We report here the other principal features observed in high resolution monochromatic synchrotron radiation diffraction images: (quasi) cellular structure; linear, very low-angle subgrain boundaries in (110) directions, and surface stripes in a (110) direction. In addition, we report systematic differences in the acceptance angle for images involving various diffraction vectors. When these observations are considered together, a unifying picture emerges. The presence of ensembles of thin (110) antiphase platelet regions or boundaries is generally consistent not only with the streak-like diffraction features but with the other features reported here as well. For the formation of such regions we propose two mechanisms, operating in parallel, that appear to be consistent with the various defect features observed by a variety of techniques.

Social and Structural Factors Associated with Consistent Condom Use Among Female Entertainment Workers Trading Sex in the Philippines

PubMed Central

Morisky, Donald E.; Hernandez, Laufred I.; Strathdee, Steffanie A.

2014-01-01

This paper examined socio-structural factors of consistent condom use among female entertainment workers at high risk for acquiring HIV in Metro Manila, Quezon City, Philippines. Entertainers, aged 18 and over, from 25 establishments (spa/saunas, night clubs, karaoke bars), who traded sex during the previous 6 months, underwent cross-sectional surveys. The 143 entertainers (42% not always using condoms, 58% always using condoms) had median age (23), duration in sex work (7 months), education (9 years), and 29% were married/had live-in boyfriends. In a logistic multiple regression model, social-structural vs. individual factors were associated with inconsistent condom use: being forced/deceived into sex work, less manager contact, less STI/HIV prevention knowledge acquired from medical personnel/professionals, not following a co-workers’ condom use advice, and an interaction between establishment type and alcohol use with establishment guests. Interventions should consider the effects of physical (force/deception into work), social (peer, manager influence), and policy (STI/HIV prevention knowledge acquired from medical personnel/professionals) environments on consistent condom use. PMID:22223297

Social and structural factors associated with consistent condom use among female entertainment workers trading sex in the Philippines.

PubMed

Urada, Lianne A; Morisky, Donald E; Hernandez, Laufred I; Strathdee, Steffanie A

2013-02-01

This paper examined socio-structural factors of consistent condom use among female entertainment workers at high risk for acquiring HIV in Metro Manila, Quezon City, Philippines. Entertainers, aged 18 and over, from 25 establishments (spa/saunas, night clubs, karaoke bars), who traded sex during the previous 6 months, underwent cross-sectional surveys. The 143 entertainers (42% not always using condoms, 58% always using condoms) had median age (23), duration in sex work (7 months), education (9 years), and 29% were married/had live-in boyfriends. In a logistic multiple regression model, social-structural vs. individual factors were associated with inconsistent condom use: being forced/deceived into sex work, less manager contact, less STI/HIV prevention knowledge acquired from medical personnel/professionals, not following a co-workers' condom use advice, and an interaction between establishment type and alcohol use with establishment guests. Interventions should consider the effects of physical (force/deception into work), social (peer, manager influence), and policy (STI/HIV prevention knowledge acquired from medical personnel/professionals) environments on consistent condom use.

Integrated photonics using colloidal quantum dots

NASA Astrophysics Data System (ADS)

Menon, Vinod M.; Husaini, Saima; Okoye, Nicky; Valappil, Nikesh V.

2009-11-01

Integrated photonic devices were realized using colloidal quantum dot composites such as flexible microcavity laser, microdisk emitters and integrated active-passive waveguides. The microcavity laser structure was realized using spin coating and consisted of an all-polymer distributed Bragg reflector with a poly-vinyl carbazole cavity layer embedded with InGaP/ZnS colloidal quantum dots. These microcavities can be peeled off the substrate yielding a flexible structure that can conform to any shape and whose emission spectra can be mechanically tuned. Planar photonic devices consisting of vertically coupled microring resonators, microdisk emitters, active-passive integrated waveguide structures and coupled active microdisk resonators were realized using soft lithography, photo-lithography, and electron beam lithography, respectively. The gain medium in all these devices was a composite consisting of quantum dots embedded in SU8 matrix. Finally, the effect of the host matrix on the optical properties of the quantum dots using results of steady-state and time-resolved luminescence measurements was determined. In addition to their specific functionalities, these novel device demonstrations and their development present a low-cost alternative to the traditional photonic device fabrication techniques.

Flow Structure Comparison for Two 7-Point LDI Configurations

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Tacina, Kathleen M.

2017-01-01

This paper presents a comparison primarily of the 2-D velocity profiles in the non-burning system; and for the luminescent flame structure for a 7-point Lean Direct Injector (LDI). This circular LDI array consists of a center element surrounded by six outer elements spaced 60 degrees apart; the spacing between all adjacent elements is the same. Each element consists of simplex atomizer that injects at the throat of a converging-diverging venturi, and an axial swirler upstream of the venturi throat to generate swirl. The two configurations were: 1) one which consists of all 60 co-swirling axial air swirlers, and; 2) one configuration which uses a 60 swirler in the center, surrounded by counter-swirling 45 swirlers. Testing was done at 5 atm and an inlet temperature of 800F. Two air reference velocities were considered in the cold flow measurements and one common air flow condition for the burning case.The 2D velocity profiles were determined using particle image velocimetry and the flame structure was determined using high speed photography.

Behavioral variability of choices versus structural inconsistency of preferences.

PubMed

Regenwetter, Michel; Davis-Stober, Clintin P

2012-04-01

Theories of rational choice often make the structural consistency assumption that every decision maker's binary strict preference among choice alternatives forms a strict weak order. Likewise, the very concept of a utility function over lotteries in normative, prescriptive, and descriptive theory is mathematically equivalent to strict weak order preferences over those lotteries, while intransitive heuristic models violate such weak orders. Using new quantitative interdisciplinary methodologies, we dissociate the variability of choices from the structural inconsistency of preferences. We show that laboratory choice behavior among stimuli of a classical "intransitivity" paradigm is, in fact, consistent with variable strict weak order preferences. We find that decision makers act in accordance with a restrictive mathematical model that, for the behavioral sciences, is extraordinarily parsimonious. Our findings suggest that the best place to invest future behavioral decision research is not in the development of new intransitive decision models but rather in the specification of parsimonious models consistent with strict weak order(s), as well as heuristics and other process models that explain why preferences appear to be weakly ordered.

Toward link predictability of complex networks

PubMed Central

Lü, Linyuan; Pan, Liming; Zhou, Tao; Zhang, Yi-Cheng; Stanley, H. Eugene

2015-01-01

The organization of real networks usually embodies both regularities and irregularities, and, in principle, the former can be modeled. The extent to which the formation of a network can be explained coincides with our ability to predict missing links. To understand network organization, we should be able to estimate link predictability. We assume that the regularity of a network is reflected in the consistency of structural features before and after a random removal of a small set of links. Based on the perturbation of the adjacency matrix, we propose a universal structural consistency index that is free of prior knowledge of network organization. Extensive experiments on disparate real-world networks demonstrate that (i) structural consistency is a good estimation of link predictability and (ii) a derivative algorithm outperforms state-of-the-art link prediction methods in both accuracy and robustness. This analysis has further applications in evaluating link prediction algorithms and monitoring sudden changes in evolving network mechanisms. It will provide unique fundamental insights into the above-mentioned academic research fields, and will foster the development of advanced information filtering technologies of interest to information technology practitioners. PMID:25659742

Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro.

PubMed

Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

2015-01-01

In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866-4550 m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies.

Factor Structure and Psychometric Properties of the Injection Phobia Scale-Anxiety

ERIC Educational Resources Information Center

Olatunji, Bunmi O.; Sawchuk, Craig N.; Moretz, Melanie W.; David, Bieke; Armstrong, Thomas; Ciesielski, Bethany G.

2010-01-01

The present investigation examined the factor structure and psychometric properties of the Injection Phobia Scale-Anxiety (IPS-Anx). Principal components analysis of IPS-Anx items in Study 1 (n = 498) revealed a 2-factor structure consisting of Distal Fear and Contact Fear. However, CFA results in Study 2 (n = 567) suggest that a 1-factor…

Scale-dependent genetic structure of the Idaho giant salamander (Dicamptodon aterrimus) in stream networks

Treesearch

Lindy B. Mullen; H. Arthur Woods; Michael K. Schwartz; Adam J. Sepulveda; Winsor H. Lowe

2010-01-01

The network architecture of streams and rivers constrains evolutionary, demographic and ecological processes of freshwater organisms. This consistent architecture also makes stream networks useful for testing general models of population genetic structure and the scaling of gene flow. We examined genetic structure and gene flow in the facultatively paedomorphic Idaho...

Software Methodology Catalog. Second Edition. Revision

DTIC Science & Technology

1989-03-01

structured design involve characterization of the data flow through graphical representation, identification of the various transform elements, assembling...and graphical diagrams to facilitate communication within the team. The diagrams are consistent with the design language and can be automatically...organization, box structure graphics provide a visual means of client communication. These box structures are used during analysis and design to review

Neutron and gamma radiation shielding material, structure, and process of making structure

DOEpatents

Hondorp, Hugh L.

1984-01-01

The present invention is directed to a novel neutron and gamma radiation elding material consisting of 95 to 97 percent by weight SiO.sub.2 and 5 to 3 percent by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

Investigating the Latent Structure of the Teacher Efficacy Scale

ERIC Educational Resources Information Center

Wagler, Amy; Wagler, Ron

2013-01-01

This article reevaluates the latent structure of the Teacher Efficacy Scale using confirmatory factor analyses (CFAs) on a sample of preservice teachers from a public university in the U.S. Southwest. The fit of a proposed two-factor CFA model with an error correlation structure consistent with internal/ external locus of control is compared to…

Reliability, Validity, and Factor Structure of the Imaginative Capability Scale

ERIC Educational Resources Information Center

Liang, Chaoyun; Chia, Tsorng-Lin

2014-01-01

Three studies were combined to test the reliability, validity, and factor structure of the imaginative capability scale (ICS). The ICS was a new self-report measure, which was developed to be empirically valid and easy to administer. Study 1 consisted in an exploratory factor analysis to determine the most appropriate structure of the ICS in a…

Structured Forms Reference Set of Binary Images (SFRS)

National Institute of Standards and Technology Data Gateway

NIST Structured Forms Reference Set of Binary Images (SFRS) (Web, free access)   The NIST Structured Forms Database (Special Database 2) consists of 5,590 pages of binary, black-and-white images of synthesized documents. The documents in this database are 12 different tax forms from the IRS 1040 Package X for the year 1988.

Stronger Consistency and Semantics for Low-Latency Geo-Replicated Storage

DTIC Science & Technology

2013-06-01

Wallach, Mike Burrows , Tushar Chandra, Andrew Fikes, and Robert E. Gruber. Bigtable: A distributed storage system for structured data. ACM TOCS, 26(2...propagation for weakly consistent replication. In SOSP, October 1997. [60] Larry Peterson, Andy Bavier, and Sapan Bhatia. VICCI: A programmable cloud

Medical operations and life sciences activities on space station

NASA Technical Reports Server (NTRS)

Johnson, P. C. (Editor); Mason, J. A. (Editor)

1982-01-01

Space station health maintenance facilities, habitability, personnel, and research in the medical sciences and in biology are discussed. It is assumed that the space station structure will consist of several modules, each being consistent with Orbiter payload bay limits in size, weight, and center of gravity.

Developing leading indicators from OHS management audit data: Determining the measurement properties of audit data from the field.

PubMed

Robson, Lynda S; Ibrahim, Selahadin; Hogg-Johnson, Sheilah; Steenstra, Ivan A; Van Eerd, Dwayne; Amick, Benjamin C

2017-06-01

OHS management audits are one means of obtaining data that may serve as leading indicators. The measurement properties of such data are therefore important. This study used data from Workwell audit program in Ontario, a Canadian province. The audit instrument consisted of 122 items related to 17 OHS management elements. The study sought answers regarding (a) the ability of audit-based scores to predict workers' compensation claims outcomes, (b) structural characteristics of the data in relation to the organization of the audit instrument, and (c) internal consistency of items within audit elements. The sample consisted of audit and claims data from 1240 unique firms that had completed one or two OHS management audits during 2007-2010. Predictors derived from the audit results were used in multivariable negative binomial regression modeling of workers' compensation claims outcomes. Confirmatory factor analyses were used to examine the instrument's structural characteristics. Kuder-Richardson coefficients of internal consistency were calculated for each audit element. The ability of audit scores to predict subsequent claims data could not be established. Factor analysis supported the audit instrument's element-based structure. KR-20 values were high (≥0.83). The Workwell audit data display structural validity and high internal consistency, but not, to date, construct validity, since the audit scores are generally not predictive of subsequent firm claim experience. Audit scores should not be treated as leading indicators of workplace OHS performance without supporting empirical data. Analyses of the measurement properties of audit data can inform decisionmakers about the operation of an audit program, possible future directions in audit instrument development, and the appropriate use of audit data. In particular, decision-makers should be cautious in their use of audit scores as leading indicators, in the absence of supporting empirical data. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

Characteristics of dental fear among Arabic-speaking children: a descriptive study.

PubMed

El-Housseiny, Azza A; Alamoudi, Najlaa M; Farsi, Najat M; El Derwi, Douaa A

2014-09-22

Dental fear has not only been linked to poor dental health in children but also persists across the lifespan, if unaddressed, and can continue to affect oral, systemic, and psychological health. The aim of this study was to assess the factor structure of the Arabic version of the Children's Fear Survey Schedule-Dental Subscale (CFSS-DS), and to assess the difference in factor structure between boys and girls. Participants were 220 consecutive paediatric dental patients 6-12 years old seeking dental care at the Faculty of Dentistry, King Abdulaziz University, Saudi Arabia. Participants completed the 15-item Arabic version of the CFSS-DS questionnaire at the end of the visit. Internal consistency was assessed using Cronbach's alpha. Factor analysis (principal components, varimax rotation) was employed to assess the factor structure of the scale. The Cronbach's alpha was 0.86. Four factors with eigenvalues above 1.00 were identified, which collectively explained 64.45% of the variance. These factors were as follows: Factor 1, 'fear of usual dental procedures' consisted of 8 items such as 'drilling' and 'having to open the mouth', Factor 2, 'fear of health care personnel and injections' consisted of three items, Factor 3, 'fear of strangers', consisted of 2 items. Factor 4, 'fear of general medical aspects of treatment', consisted of 2 items. Notably, four factors of dental fear were found in girls, while five were found in boys. Four factors of different strength pertaining to dental fear were identified in Arabic-speaking children, indicating a simple structure. Most items loaded high on the factor related to fear of usual dental procedures. The fear-provoking aspects of dental procedures differed in boys and girls. Use of the scale may enable dentists to determine the item/s of dental treatment that a given child finds most fear-provoking and guide the child's behaviour accordingly.

Reliability, factor analysis and internal consistency calculation of the Insomnia Severity Index (ISI) in French and in English among Lebanese adolescents.

PubMed

Chahoud, M; Chahine, R; Salameh, P; Sauleau, E A

2017-06-01

Our goal is to validate and to verify the reliability of the French and English versions of the Insomnia Severity Index (ISI) in Lebanese adolescents. A cross-sectional study was implemented. 104 Lebanese students aged between 14 and 19 years participated in the study. The English version of the questionnaire was distributed to English-speaking students and the French version was administered to French-speaking students. A scale (1 to 7 with 1 = very well understood and 7 = not at all) was used to identify the level of the students' understanding of each instruction, question and answer of the ISI. The scale's structural validity was assessed. The factor structure of ISI was evaluated by principal component analysis. The internal consistency of this scale was evaluated by Cronbach's alpha. To assess test-retest reliability the intraclass correlation coefficient (ICC) was used. The principal component analysis confirmed the presence of a two-component factor structure in the English version and a three-component factor structure in the French version with eigenvalues > 1. The English version of the ISI had an excellent internal consistency (α = 0.90), while the French version had a good internal consistency (α = 0.70). The ICC presented an excellent agreement in the French version (ICC = 0.914, CI = 0.856-0.949) and a good agreement in the English one (ICC = 0.762, CI = 0.481-890). The Bland-Altman plots of the two versions of the ISI showed that the responses over two weeks' were comparable and very few outliers were detected. The results of our analyses reveal that both English and French versions of the ISI scale have good internal consistency and are reproducible and reliable. Therefore, it can be used to assess the prevalence of insomnia in Lebanese adolescents.

Growth of second stage mineral in Lytechinus variegatus.

PubMed

Stock, S R; Seto, Jong; Deymier, A C; Rack, A; Veis, A

2017-10-30

Purpose and Aims: Sea urchin teeth consist of calcite and form in two stages with different magnesium contents. The first stage structures of independently formed plates and needle-prisms define the shape of the tooth, and the columns of the second stage mineral cements the first stage structures together and control the fracture behavior of the mature tooth. This study investigates the nucleation and growth of the second stage mineral. Scanning electron microscopy (SEM) and synchrotron microComputed Tomography characterized the structures of the second phase material found in developing of Lytechinus variegatus teeth. Although the column development is a continuous process, defining four phases of column formation captures the changes that occur in teeth of L. variegatus. The earliest phase consists of small 1-2 µm diameter hemispheres, and the second of 5-10 µm diameter, mound-like structures with a nodular surface, develops from the hemispheres. The mounds eventually bridge the syncytium between adjacent plates and form hyperboloid structures (phase three) that appear like mesas when plates separate during the fracture. The mesa diameter increases with time until the column diameter is significantly larger than its height, defining the fourth phase of column development. Energy dispersive x-ray spectroscopy confirms that the columns contain more magnesium than the underlying plates; the ratios of magnesium to calcium are consistent with compositions derived from x-ray diffraction. Columns grow from both bounding plates. The presence of first phase columns interspersed among third stage mesas indicates very localized control of mineralization.

Structural design guidelines for concrete bridge decks reinforced with corrosion-resistant reinforcing bars.

DOT National Transportation Integrated Search

2014-10-01

This research program develops and validates structural design guidelines and details for concrete bridge decks with : corrosion-resistant reinforcing (CRR) bars. A two-phase experimental program was conducted where a control test set consistent : wi...

Observation of J/ψϕ Structures Consistent with Exotic States from Amplitude Analysis of B^{+}→J/ψϕK^{+} Decays.

PubMed

Aaij, R; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Andreassi, G; Andreotti, M; Andrews, J E; Appleby, R B; Aquines Gutierrez, O; Archilli, F; d'Argent, P; Arnau Romeu, J; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Babuschkin, I; Bachmann, S; Back, J J; Badalov, A; Baesso, C; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Batozskaya, V; Batsukh, B; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Bel, L J; Bellee, V; Belloli, N; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bertolin, A; Betti, F; Bettler, M-O; van Beuzekom, M; Bezshyiko, I; Bifani, S; Billoir, P; Bird, T; Birnkraut, A; Bitadze, A; Bizzeti, A; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Boettcher, T; Bondar, A; Bondar, N; Bonivento, W; Borgheresi, A; Borghi, S; Borisyak, M; Borsato, M; Bossu, F; Boubdir, M; Bowcock, T J V; Bowen, E; Bozzi, C; Braun, S; Britsch, M; Britton, T; Brodzicka, J; Buchanan, E; Burr, C; Bursche, A; Buytaert, J; Cadeddu, S; Calabrese, R; Calvi, M; Calvo Gomez, M; Campana, P; Campora Perez, D; Capriotti, L; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carniti, P; Carson, L; Carvalho Akiba, K; Casse, G; Cassina, L; Castillo Garcia, L; Cattaneo, M; Cauet, Ch; Cavallero, G; Cenci, R; Charles, M; Charpentier, Ph; Chatzikonstantinidis, G; Chefdeville, M; Chen, S; Cheung, S-F; Chobanova, V; Chrzaszcz, M; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coco, V; Cogan, J; Cogneras, E; Cogoni, V; Cojocariu, L; Collazuol, G; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coquereau, S; Corti, G; Corvo, M; Costa Sobral, C M; Couturier, B; Cowan, G A; Craik, D C; Crocombe, A; Cruz Torres, M; Cunliffe, S; Currie, R; D'Ambrosio, C; Dall'Occo, E; Dalseno, J; David, P N Y; Davis, A; De Aguiar Francisco, O; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Serio, M; De Simone, P; Dean, C-T; Decamp, D; Deckenhoff, M; Del Buono, L; Demmer, M; Derkach, D; Deschamps, O; Dettori, F; Dey, B; Di Canto, A; Dijkstra, H; Dordei, F; Dorigo, M; Dosil Suárez, A; Dovbnya, A; Dreimanis, K; Dufour, L; Dujany, G; Dungs, K; Durante, P; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Déléage, N; Easo, S; Egede, U; Egorychev, V; Eidelman, S; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; Elsasser, Ch; Ely, S; Esen, S; Evans, H M; Evans, T; Falabella, A; Farley, N; Farry, S; Fay, R; Fazzini, D; Ferguson, D; Fernandez Albor, V; Ferrari, F; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fini, R A; Fiore, M; Fiorini, M; Firlej, M; Fitzpatrick, C; Fiutowski, T; Fleuret, F; Fohl, K; Fontana, M; Fontanelli, F; Forshaw, D C; Forty, R; Frank, M; Frei, C; Fu, J; Furfaro, E; Färber, C; Gallas Torreira, A; Galli, D; Gallorini, S; Gambetta, S; Gandelman, M; Gandini, P; Gao, Y; García Pardiñas, J; Garra Tico, J; Garrido, L; Garsed, P J; Gascon, D; Gaspar, C; Gavardi, L; Gazzoni, G; Gerick, D; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gianì, S; Gibson, V; Girard, O G; Giubega, L; Gizdov, K; Gligorov, V V; Golubkov, D; Golutvin, A; Gomes, A; Gorelov, I V; Gotti, C; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graverini, E; Graziani, G; Grecu, A; Griffith, P; Grillo, L; Gruberg Cazon, B R; Grünberg, O; Gushchin, E; Guz, Yu; Gys, T; Göbel, C; Hadavizadeh, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hamilton, B; Han, X; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Hatch, M; He, J; Head, T; Heister, A; Hennessy, K; Henrard, P; Henry, L; Hernando Morata, J A; van Herwijnen, E; Heß, M; Hicheur, A; Hill, D; Hombach, C; Hulsbergen, W; Humair, T; Hushchyn, M; Hussain, N; Hutchcroft, D; Idzik, M; Ilten, P; Jacobsson, R; Jaeger, A; Jalocha, J; Jans, E; Jawahery, A; John, M; Johnson, D; Jones, C R; Joram, C; Jost, B; Jurik, N; Kandybei, S; Kanso, W; Karacson, M; Kariuki, J M; Karodia, S; Kecke, M; Kelsey, M; Kenyon, I R; Kenzie, M; Ketel, T; Khairullin, E; Khanji, B; Khurewathanakul, C; Kirn, T; Klaver, S; Klimaszewski, K; Koliiev, S; Kolpin, M; Komarov, I; Koopman, R F; Koppenburg, P; Kozachuk, A; Kozeiha, M; Kravchuk, L; Kreplin, K; Kreps, M; Krokovny, P; Kruse, F; Krzemien, W; Kucewicz, W; Kucharczyk, M; Kudryavtsev, V; Kuonen, A K; Kurek, K; Kvaratskheliya, T; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lanfranchi, G; Langenbruch, C; Langhans, B; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Leflat, A; Lefrançois, J; Lefèvre, R; Lemaitre, F; Lemos Cid, E; Leroy, O; Lesiak, T; Leverington, B; Li, Y; Likhomanenko, T; Lindner, R; Linn, C; Lionetto, F; Liu, B; Liu, X; Loh, D; Longstaff, I; Lopes, J H; Lucchesi, D; Lucio Martinez, M; Luo, H; Lupato, A; Luppi, E; Lupton, O; Lusiani, A; Lyu, X; Machefert, F; Maciuc, F; Maev, O; Maguire, K; Malde, S; Malinin, A; Maltsev, T; Manca, G; Mancinelli, G; Manning, P; Maratas, J; Marchand, J F; Marconi, U; Marin Benito, C; Marino, P; Marks, J; Martellotti, G; Martin, M; Martinelli, M; Martinez Santos, D; Martinez Vidal, F; Martins Tostes, D; Massacrier, L M; Massafferri, A; Matev, R; Mathad, A; Mathe, Z; Matteuzzi, C; Mauri, A; Maurin, B; Mazurov, A; McCann, M; McCarthy, J; McNab, A; McNulty, R; Meadows, B; Meier, F; Meissner, M; Melnychuk, D; Merk, M; Merli, A; Michielin, E; Milanes, D A; Minard, M-N; Mitzel, D S; Molina Rodriguez, J; Monroy, I A; Monteil, S; Morandin, M; Morawski, P; Mordà, A; Morello, M J; Moron, J; Morris, A B; Mountain, R; Muheim, F; Mulder, M; Mussini, M; Müller, D; Müller, J; Müller, K; Müller, V; Naik, P; Nakada, T; Nandakumar, R; Nandi, A; Nasteva, I; Needham, M; Neri, N; Neubert, S; Neufeld, N; Neuner, M; Nguyen, A D; Nguyen-Mau, C; Nieswand, S; Niet, R; Nikitin, N; Nikodem, T; Novoselov, A; O'Hanlon, D P; Oblakowska-Mucha, A; Obraztsov, V; Ogilvy, S; Oldeman, R; Onderwater, C J G; Otalora Goicochea, J M; Otto, A; Owen, P; Oyanguren, A; Pais, P R; Palano, A; Palombo, F; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Pappalardo, L L; Pappenheimer, C; Parker, W; Parkes, C; Passaleva, G; Pastore, A; Patel, G D; Patel, M; Patrignani, C; Pearce, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perret, P; Pescatore, L; Petridis, K; Petrolini, A; Petrov, A; Petruzzo, M; Picatoste Olloqui, E; Pietrzyk, B; Pikies, M; Pinci, D; Pistone, A; Piucci, A; Playfer, S; Plo Casasus, M; Poikela, T; Polci, F; Poluektov, A; Polyakov, I; Polycarpo, E; Pomery, G J; Popov, A; Popov, D; Popovici, B; Potterat, C; Price, E; Price, J D; Prisciandaro, J; Pritchard, A; Prouve, C; Pugatch, V; Puig Navarro, A; Punzi, G; Qian, W; Quagliani, R; Rachwal, B; Rademacker, J H; Rama, M; Ramos Pernas, M; Rangel, M S; Raniuk, I; Raven, G; Redi, F; Reichert, S; Dos Reis, A C; Remon Alepuz, C; Renaudin, V; Ricciardi, S; Richards, S; Rihl, M; Rinnert, K; Rives Molina, V; Robbe, P; Rodrigues, A B; Rodrigues, E; Rodriguez Lopez, J A; Rodriguez Perez, P; Rogozhnikov, A; Roiser, S; Romanovskiy, V; Romero Vidal, A; Ronayne, J W; Rotondo, M; Ruf, T; Ruiz Valls, P; Saborido Silva, J J; Sadykhov, E; Sagidova, N; Saitta, B; Salustino Guimaraes, V; Sanchez Mayordomo, C; Sanmartin Sedes, B; Santacesaria, R; Santamarina Rios, C; Santimaria, M; Santovetti, E; Sarti, A; Satriano, C; Satta, A; Saunders, D M; Savrina, D; Schael, S; Schellenberg, M; Schiller, M; Schindler, H; Schlupp, M; Schmelling, M; Schmelzer, T; Schmidt, B; Schneider, O; Schopper, A; Schubert, K; Schubiger, M; Schune, M-H; Schwemmer, R; Sciascia, B; Sciubba, A; Semennikov, A; Sergi, A; Serra, N; Serrano, J; Sestini, L; Seyfert, P; Shapkin, M; Shapoval, I; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, V; Shires, A; Siddi, B G; Silva Coutinho, R; Silva de Oliveira, L; Simi, G; Simone, S; Sirendi, M; Skidmore, N; Skwarnicki, T; Smith, E; Smith, I T; Smith, J; Smith, M; Snoek, H; Sokoloff, M D; Soler, F J P; Souza, D; Souza De Paula, B; Spaan, B; Spradlin, P; Sridharan, S; Stagni, F; Stahl, M; Stahl, S; Stefko, P; Stefkova, S; Steinkamp, O; Stenyakin, O; Stevenson, S; Stoica, S; Stone, S; Storaci, B; Stracka, S; Straticiuc, M; Straumann, U; Sun, L; Sutcliffe, W; Swientek, K; Syropoulos, V; Szczekowski, M; Szumlak, T; T'Jampens, S; Tayduganov, A; Tekampe, T; Tellarini, G; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Tolk, S; Tomassetti, L; Tonelli, D; Topp-Joergensen, S; Toriello, F; Tournefier, E; Tourneur, S; Trabelsi, K; Traill, M; Tran, M T; Tresch, M; Trisovic, A; Tsaregorodtsev, A; Tsopelas, P; Tully, A; Tuning, N; Ukleja, A; Ustyuzhanin, A; Uwer, U; Vacca, C; Vagnoni, V; Valat, S; Valenti, G; Vallier, A; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; van Veghel, M; Velthuis, J J; Veltri, M; Veneziano, G; Venkateswaran, A; Vernet, M; Vesterinen, M; Viaud, B; Vieira, D; Vieites Diaz, M; Vilasis-Cardona, X; Volkov, V; Vollhardt, A; Voneki, B; Voong, D; Vorobyev, A; Vorobyev, V; Voß, C; de Vries, J A; Vázquez Sierra, C; Waldi, R; Wallace, C; Wallace, R; Walsh, J; Wang, J; Ward, D R; Wark, H M; Watson, N K; Websdale, D; Weiden, A; Whitehead, M; Wicht, J; Wilkinson, G; Wilkinson, M; Williams, M; Williams, M P; Williams, M; Williams, T; Wilson, F F; Wimberley, J; Wishahi, J; Wislicki, W; Witek, M; Wormser, G; Wotton, S A; Wraight, K; Wright, S; Wyllie, K; Xie, Y; Xing, Z; Xu, Z; Yang, Z; Yin, H; Yu, J; Yuan, X; Yushchenko, O; Zangoli, M; Zarebski, K A; Zavertyaev, M; Zhang, L; Zhang, Y; Zhang, Y; Zhelezov, A; Zheng, Y; Zhokhov, A; Zhukov, V; Zucchelli, S

2017-01-13

The first full amplitude analysis of B^{+}→J/ψϕK^{+} with J/ψ→μ^{+}μ^{-}, ϕ→K^{+}K^{-} decays is performed with a data sample of 3  fb^{-1} of pp collision data collected at sqrt[s]=7 and 8 TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into ϕK^{+}, and four J/ψϕ structures are observed, each with significance over 5 standard deviations. The quantum numbers of these structures are determined with significance of at least 4 standard deviations. The lightest has mass consistent with, but width much larger than, previous measurements of the claimed X(4140) state.

Ordered mixed-layer structures in the Mighei carbonaceous chondrite matrix

NASA Technical Reports Server (NTRS)

Mackinnon, I. D. R.

1982-01-01

High resolution transmission electron microscopy of the Mighei carbonaceous chondrite matrix has revealed the presence of a new mixed layer structure material. This mixed-layer material consists of an ordered arrangement of serpentine-type (S) and brucite-type (B) layers in the sequence SBBSBB. Electron diffraction and imaging techniques show that the basal periodicity is approximately 17 A. Discrete crystals of SBB-type material are typically curved, of small size (less than 1 micron) and show structural variations similar to the serpentine group minerals. Mixed-layer material also occurs in association with planar serpentine. Characteristics of SBB-type material are not consistent with known terrestrial mixed-layer clay minerals. Evidence for formation by a condensation event or by subsequent alteration of pre-existing material is not yet apparent.

The stable clustering ansatz, consistency relations and gravity dual of large-scale structure

NASA Astrophysics Data System (ADS)

Munshi, Dipak

2018-02-01

Gravitational clustering in the nonlinear regime remains poorly understood. Gravity dual of gravitational clustering has recently been proposed as a means to study the nonlinear regime. The stable clustering ansatz remains a key ingredient to our understanding of gravitational clustering in the highly nonlinear regime. We study certain aspects of violation of the stable clustering ansatz in the gravity dual of Large Scale Structure (LSS). We extend the recent studies of gravitational clustering using AdS gravity dual to take into account possible departure from the stable clustering ansatz and to arbitrary dimensions. Next, we extend the recently introduced consistency relations to arbitrary dimensions. We use the consistency relations to test the commonly used models of gravitational clustering including the halo models and hierarchical ansätze. In particular we establish a tower of consistency relations for the hierarchical amplitudes: Q, Ra, Rb, Sa,Sb,Sc etc. as a functions of the scaled peculiar velocity h. We also study the variants of popular halo models in this context. In contrast to recent claims, none of these models, in their simplest incarnation, seem to satisfy the consistency relations in the soft limit.

Psychometric Properties of the Dutch Depression Stigma Scale (DSS) and Associations with Personal and Perceived Stigma in a Depressed and Community Sample

PubMed Central

Cuijpers, P.; Griffiths, K. M.; Kleiboer, A. M.

2016-01-01

Background Research on depression stigma is needed to gain more insight into the underlying construct and to reduce the level of stigma in the community. However, few validated measurements of depression stigma are available in the Netherlands. Therefore, this study first sought to examine the psychometric properties of the Dutch translation of the Depression Stigma Scale (DSS). Second, we examined which demographic (gender, age, education, partner status) and other variables (anxiety and knowledge of depression) are associated with personal and perceived stigma within these samples. Methods The study population consisted of an adult convenience sample (n = 253) (study 1) and a community adult sample with elevated depressive symptoms (n = 264) (study 2). Factor structure, internal consistency, and validity were assessed. The associations between stigma, demographic variables and anxiety level were examined with regression analyses. Results Confirmatory factor analysis supported the validity and internal consistency of the DSS personal stigma scale. Internal consistency was sufficient (Cronbach’s alpha = .70 (study 1) and .77 (study 2)). The results regarding the perceived stigma scale revealed no clear factor structure. Regression analyses showed that personal stigma was higher in younger people, those with no experience with depression, and those with lower education. Conclusions This study established the validity and internal consistency of the DSS personal scale in the Netherlands, in a community sample and in people with elevated depressive symptoms. However, additional research is needed to examine the factor structure of the DSS perceived scale and its use in other samples. PMID:27500969

Electronic structures of of PuX (X=S, Se, Te)

NASA Astrophysics Data System (ADS)

Maehira, Takahiro; Sakai, Eijiro; Tatetsu, Yasutomi

2013-08-01

We have calculated the energy band structures and the Fermi surfaces of PuS, PuSe, and PuTe by using a self-consistent relativistic linear augmented-plane-wave method with the exchange and correlation potential in the local density approximation. In general, the energy bands near the Fermi level are mainly caused by the hybridization between the Pu 5 f and the monochalcogenide p electrons. The obtained main Fermi surfaces consisted of two hole sheets and one electron sheet, which were constructed from the band having both the Pu 5 f state and the monochalcogenide p state.

Structural concepts for large solar concentrators

NASA Technical Reports Server (NTRS)

Hedgepeth, J. M.; Miller, R. K.

1986-01-01

Solar collectors for space use are examined, including both early designs and current concepts. In particular, attention is given to stiff sandwich panels and aluminum dishes as well as inflated and umbrella-type membrane configurations. The Sunflower concentrator is described as an example of a high-efficiency collector. It is concluded that stiff reflector panels are most likely to provide the long-term consistent accuracy necessary for low-orbit operation. A new configuration consisting of a Pactruss backup structure, with identical panels installed after deployment in space, is presented. It is estimated that concentration ratios in excess of 2000 can be achieved with this concept.

Lipid Bilayer Vesicles with Numbers of Membrane-Linking Pores

NASA Astrophysics Data System (ADS)

Ken-ichirou Akashi,; Hidetake Miyata,

2010-06-01

We report that phospholipid membranes spontaneously formed in aqueous medium giant unilamellar vesicles (GUVs) possessing many membranous wormhole-like structures (membrane-linking pores, MLPs). By phase contract microscopy and confocal fluorescence microscopy, the structures of the MLPs, consisting of lipid bilayer, were resolvable, and a variety of vesicular shapes having many MLPs (a high genus topology) were found. These vesicles were stable but easily deformed by micromanipulation with a microneedle. We also observed the size reduction of the MLPs with the increase in membrane tension, which was qualitatively consistent with a prediction from a simple dynamical model.

Decay width of hadronic molecule structure for quarks

NASA Astrophysics Data System (ADS)

Chen, Xiaozhao; Lü, Xiaofu

2018-06-01

Based on the general form of the Bethe-Salpeter wave functions for the bound states consisting of two vector fields, we obtain the general formulas for the decay widths of molecular states composed of two heavy vector mesons with arbitrary spin and parity into a heavy meson plus a light meson. In this approach, our attention is still focused on the internal structure of heavy vector mesons in the molecular state. According to the molecule state model of exotic meson, we give the generalized Bethe-Salpeter wave function of molecular state as a four-quark state. Then the observed Y (3940 ) state is considered as a molecular state consisting of two heavy vector mesons D*0D¯*0 and the strong Y (3940 )→J /ψ ω decay width is calculated. The numerical result is consistent with the experimental values.

Grammatical Encoding and Learning in Agrammatic Aphasia: Evidence from Structural Priming

PubMed Central

Cho-Reyes, Soojin; Mack, Jennifer E.; Thompson, Cynthia K.

2017-01-01

The present study addressed open questions about the nature of sentence production deficits in agrammatic aphasia. In two structural priming experiments, 13 aphasic and 13 age-matched control speakers repeated visually- and auditorily-presented prime sentences, and then used visually-presented word arrays to produce dative sentences. Experiment 1 examined whether agrammatic speakers form structural and thematic representations during sentence production, whereas Experiment 2 tested the lasting effects of structural priming in lags of two and four sentences. Results of Experiment 1 showed that, like unimpaired speakers, the aphasic speakers evinced intact structural priming effects, suggesting that they are able to generate such representations. Unimpaired speakers also evinced reliable thematic priming effects, whereas agrammatic speakers did so in some experimental conditions, suggesting that access to thematic representations may be intact. Results of Experiment 2 showed structural priming effects of comparable magnitude for aphasic and unimpaired speakers. In addition, both groups showed lasting structural priming effects in both lag conditions, consistent with implicit learning accounts. In both experiments, aphasic speakers with more severe language impairments exhibited larger priming effects, consistent with the “inverse preference” prediction of implicit learning accounts. The findings indicate that agrammatic speakers are sensitive to structural priming across levels of representation and that such effects are lasting, suggesting that structural priming may be beneficial for the treatment of sentence production deficits in agrammatism. PMID:28924328

SAbDab: the structural antibody database

PubMed Central

Dunbar, James; Krawczyk, Konrad; Leem, Jinwoo; Baker, Terry; Fuchs, Angelika; Georges, Guy; Shi, Jiye; Deane, Charlotte M.

2014-01-01

Structural antibody database (SAbDab; http://opig.stats.ox.ac.uk/webapps/sabdab) is an online resource containing all the publicly available antibody structures annotated and presented in a consistent fashion. The data are annotated with several properties including experimental information, gene details, correct heavy and light chain pairings, antigen details and, where available, antibody–antigen binding affinity. The user can select structures, according to these attributes as well as structural properties such as complementarity determining region loop conformation and variable domain orientation. Individual structures, datasets and the complete database can be downloaded. PMID:24214988

Shell structures in aluminum nanocontacts at elevated temperatures

PubMed Central

2012-01-01

Aluminum nanocontact conductance histograms are studied experimentally from room temperature up to near the bulk melting point. The dominant stable configurations for this metal show a very early crossover from shell structures at low wire diameters to ionic subshell structures at larger diameters. At these larger radii, the favorable structures are temperature-independent and consistent with those expected for ionic subshell (faceted) formations in face-centered cubic geometries. When approaching the bulk melting temperature, these local stability structures become less pronounced as shown by the vanishing conductance histogram peak structure. PMID:22325572

The Selective Mutism Questionnaire: Measurement Structure and Validity

PubMed Central

Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.; Roesch, Scott C.

2010-01-01

Objective To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire. Method Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children - Parent Version (ADIS-C/P); SM severity was assessed using the 17-item Selective Mutism Questionnaire (SMQ); and behavioral and affective symptoms were assessed using the Child Behavior Checklist (CBCL). An exploratory factor analysis (EFA) was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm EFA results. Internal consistency, construct validity, and incremental validity were also examined. Results The EFA yielded a 13-item solution consisting of three factors: a) Social Situations Outside of School, b) School Situations, and c) Home and Family Situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity were also well supported. Conclusions Measure structure findings are consistent with the 3-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomenon beyond other child anxiety measures. PMID:18698268

Isolation of Thermal and Strain Responses in Composites Using Embedded Fiber Bragg Grating Temperature Sensors

DTIC Science & Technology

2013-05-10

13. SUPPLEMENTARY NOTES 14. ABSTRACT In this research, fiber Bragg grating ( FBG ) optical temperature sensors are used for structural health...surface of a composite structure. FBG sensors also respond to axial strain in the optical fiber, thus any structural strain experienced by the composite...features. First, a three-dimensional array of FBG temperature sensors has been embedded in a carbon/epoxy composite structure, consisting of both in

Theoretical study of the noble metals on semiconductor surfaces and Ti-base shape memory alloys

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

Ding, Yungui

1994-07-27

The electronic and structural properties of the (√3 x√3) R30° Ag/Si(111) and (√3 x √3) R30° Au/Si(111) surfaces are investigated using first principles total energy calculations. We have tested almost all experimentally proposed structural models for both surfaces and found the energetically most favorable model for each of them. The lowest energy model structure of the (√3 x √3) R30° Ag/Si(111) surface consists of a top layer of Ag atoms arranged as ``honeycomb-chained-trimers`` lying above a distorted ``missing top layer`` Si(111) substrate. The coverage of Ag is 1 monolayer (ML). We find that the honeycomb structure observed in STM imagesmore » arise from the electronic charge densities of an empty surface band near the Fermi level. The electronic density of states of this model gives a ``pseudo-gap`` around the Fermi level, which is consistent with experimental results. The lowest energy model for the (√3 x √3) R30° Au/Si(111) surface is a conjugate honeycomb-chained-trimer (CHCT-1) configuration which consists of a top layer of trimers formed by 1 ML Au atoms lying above a ``missing top layer`` Si(111) substrate with a honeycomb-chained-trimer structure for its first layer. The structures of Au and Ag are in fact quite similar and belong to the same class of structural models. However, small variation in the structural details gives rise to quite different observed STM images, as revealed in the theoretical calculations. The electronic charge density from bands around the Fermi level for the (√3 x √3) R30°, Au/Si(111) surface also gives a good description of the images observed in STM experiments. First principles calculations are performed to study the electronic and structural properties of a series of Ti-base binary alloys TiFe, TiNi, TiPd, TiMo, and TiAu in the B2 structure.« less

X-ray structure of the metcyano form of dehaloperoxidase from Amphitrite ornata: evidence for photoreductive dissociation of the iron-cyanide bond

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

de Serrano, V.S.; Davis, M.F.; Gaff, J.F.

X-ray crystal structures of the metcyano form of dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata (DHPCN) and the C73S mutant of DHP A (C73SCN) were determined using synchrotron radiation in order to further investigate the geometry of diatomic ligands coordinated to the heme iron. The DHPCN structure was also determined using a rotating-anode source. The structures show evidence of photoreduction of the iron accompanied by dissociation of bound cyanide ion (CN{sup -}) that depend on the intensity of the X-ray radiation and the exposure time. The electron density is consistent with diatomic molecules located in two sites in the distal pocketmore » of DHPCN. However, the identities of the diatomic ligands at these two sites are not uniquely determined by the electron-density map. Consequently, density functional theory calculations were conducted in order to determine whether the bond lengths, angles and dissociation energies are consistent with bound CN{sup -} or O{sub 2} in the iron-bound site. In addition, molecular-dynamics simulations were carried out in order to determine whether the dynamics are consistent with trapped CN{sup -} or O{sub 2} in the second site of the distal pocket. Based on these calculations and comparison with a previously determined X-ray crystal structure of the C73S-O{sub 2} form of DHP [de Serrano et al. (2007), Acta Cryst. D63, 1094-1101], it is concluded that CN{sup -} is gradually replaced by O{sub 2} as crystalline DHP is photoreduced at 100 K. The ease of photoreduction of DHP A is consistent with the reduction potential, but suggests an alternative activation mechanism for DHP A compared with other peroxidases, which typically have reduction potentials that are 0.5 V more negative. The lability of CN{sup -} at 100 K suggests that the distal pocket of DHP A has greater flexibility than most other hemoglobins.« less

Phonological Similarity in American Sign Language.

ERIC Educational Resources Information Center

Hildebrandt, Ursula; Corina, David

2002-01-01

Investigates deaf and hearing subjects' ratings of American Sign Language (ASL) signs to assess whether linguistic experience shapes judgments of sign similarity. Findings are consistent with linguistic theories that posit movement and location as core structural elements of syllable structure in ASL. (Author/VWL)

View northwest of building 19 area used for pattern shop ...

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

View northwest of building 19 area used for pattern shop storage (foreground), building 17 section of structure on left. This structure consists of two formerly separate buildings. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Machine Shops, League Island, Philadelphia, Philadelphia County, PA

Safe Emergency Evacuation From Tall Structures

NASA Technical Reports Server (NTRS)

Stephan, E. S.

1984-01-01

Emergency egress system allows people to be evacuated quickly from tall structures. New emergency system applicable to rescues from fires in tall hotels and other buildings. System consists of basket on slide wire. Basket descends by gravity on sloped slide wire staked to ground.

Microstructure of Desmanthus illinoensis

USDA-ARS?s Scientific Manuscript database

Structure and histochemistry of mature seeds of Desmanthus illinoensis (Illinois bundle flower) show that the seed has typical legume structure. The seed can be separated into two major fractions including the seed coat/endosperm and the embryo. The seed coat consists of a cuticle, palisade sclereid...

QCD analysis of neutrino charged current structure function F2 in deep inelastic scattering

NASA Technical Reports Server (NTRS)

Saleem, M.; Aleem, F.

1985-01-01

An analytic expression for the neutrino charged current structure function F sub 2 (x, Q sup 2) in deep inelastic scattering, consistent with quantum chromodynamics, is proposed. The calculated results are in good agreement with experiment.

Electronic and structural properties of Lu under pressure: Relation to structural phases of the rare-earth metals

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

Min, B.I.; Oguchi, T.; Jansen, H.J.F.

1986-07-15

Ground-state electronic and structural properties of Lu under pressure are investigated with use of the self-consistent all-electron total-energy linear muffin-tin orbital band-structure method within a local-density-functional approximation. Pressure-induced structural transitions are found to occur in the following sequence: hcp--(Sm-type)--dhcp--fcc, which is the same as that observed in the crystal structures of the trivalent rare-earth metals with decreasing atomic number. This structural transition is correlated with the increase in the number of d-italic electrons under pressure.

Examining the Factor Structure and Hierarchical Nature of the Quality of Life Construct

ERIC Educational Resources Information Center

Wang, Mian; Schalock, Robert L.; Verdugo, Miguel A.; Jenaro, Christina

2010-01-01

There is considerable debate in the area of individual quality of life research regarding the factor structure and hierarchical nature of the quality of life construct. Our purpose in this study was to test via structural equation modeling an a priori quality of life model consisting of eight first-order factors and one second-order factor. Data…

A Combined fMRI and DTI Examination of Functional Language Lateralization and Arcuate Fasciculus Structure: Effects of Degree versus Direction of Hand Preference

ERIC Educational Resources Information Center

Propper, Ruthe E.; O'Donnell, Lauren J.; Whalen, Stephen; Tie, Yanmei; Norton, Isaiah H.; Suarez, Ralph O.; Zollei, Lilla; Radmanesh, Alireza; Golby, Alexandra J.

2010-01-01

The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca's and Wernicke's areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals,…

Resin selection criteria for tough composite structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Smith, G. T.

1983-01-01

Resin selection criteria are derived using a structured methodology consisting of an upward integrated mechanistic theory and its inverse (top-down structured theory). These criteria are expressed in a "criteria selection space" which are used to identify resin bulk properties for improved composite "toughness". The resin selection criteria correlate with a variety of experimental data including laminate strength, elevated temperature effects and impact resistance.

12 CFR 1273.7 - Structure of the OF board of directors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 12 Banks and Banking 9 2013-01-01 2013-01-01 false Structure of the OF board of directors. 1273.7 Section 1273.7 Banks and Banking FEDERAL HOUSING FINANCE AGENCY FEDERAL HOME LOAN BANKS OFFICE OF FINANCE § 1273.7 Structure of the OF board of directors. (a) Membership. The OF board of directors shall consist...

12 CFR 1273.7 - Structure of the OF board of directors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 12 Banks and Banking 9 2012-01-01 2012-01-01 false Structure of the OF board of directors. 1273.7 Section 1273.7 Banks and Banking FEDERAL HOUSING FINANCE AGENCY FEDERAL HOME LOAN BANKS OFFICE OF FINANCE § 1273.7 Structure of the OF board of directors. (a) Membership. The OF board of directors shall consist...

The Categorical Structure of Semantic Memory for Famous People: A New Approach Using Release from Proactive Interference

ERIC Educational Resources Information Center

Darling, S.; Valentine, T.

2005-01-01

Memory for familiar people is essential to understand their identity and guide social interaction. Nevertheless, we know surprisingly little about the structure of such memory. Previous research has assumed that semantic memory for people has a categorical structure, but recently it was proposed that memory for people consists only of associations…

Mapping wildland fuels and forest structure for land management: a comparison of nearest neighbor imputation and other methods

Treesearch

Kenneth B. Pierce; Janet L. Ohmann; Michael C. Wimberly; Matthew J. Gregory; Jeremy S. Fried

2009-01-01

Land managers need consistent information about the geographic distribution of wildland fuels and forest structure over large areas to evaluate fire risk and plan fuel treatments. We compared spatial predictions for 12 fuel and forest structure variables across three regions in the western United States using gradient nearest neighbor (GNN) imputation, linear models (...

Structure and biodiversity of coralligenous assemblages dominated by the precious red coral Corallium rubrum over broad spatial scales

PubMed Central

Casas-Güell, Edgar; Cebrian, Emma; Garrabou, Joaquim; Ledoux, Jean-Baptiste; Linares, Cristina; Teixidó, Núria

2016-01-01

Data on species diversity and structure in coralligenous outcrops dominated by Corallium rubrum are lacking. A hierarchical sampling including 3 localities and 9 sites covering more than 400 km of rocky coasts in NW Mediterranean, was designed to characterize the spatial variability of structure, composition and diversity of perennial species inhabiting coralligenous outcrops. We estimated species/taxa composition and abundance. Eight morpho-functional groups were defined according to their life span and growth to characterize the structural complexity of the outcrops. The species composition and structural complexity differed consistently across all spatial scales considered. The lowest and the highest variability were found among localities (separated by >200 km) and within sites (separated by 1–5 km), respectively supporting differences in diversity indices. The morpho-functional groups displayed a consistent spatial arrangement in terms of the number, size and shape of patches across study sites. These results contribute to filling the gap on the understanding of assemblage composition and structure and to build baselines to assess the response of this of this highly threatened habitat to anthropogenic disturbances. PMID:27857209

Crystal structure of low-symmetry rondorfite

NASA Astrophysics Data System (ADS)

Rastsvetaeva, R. K.; Zadov, A. E.; Chukanov, N. V.

2008-03-01

The crystal structure of an aluminum-rich variety of the mineral rondorfite with the composition Ca16[Mg2(Si7Al)(O31OH)]Cl4 from the skarns of the Verkhne-Chegemskoe plateau (the Kabardino-Balkarian Republic, the Northern Caucasus Region, Russia) was solved in the triclinic space group with the unit-cell parameters a = 15.100(2) Å, b = 15.110(2) Å, c = 15.092(2) Å, α = 90.06(1)°, β = 90.01(1)°, γ = 89.93(1)°, Z = 4, sp. gr. P1. The structural model consisting of 248 independent atoms was determined by the phase-correction method and refined to R = 3.8% with anisotropic displacement parameters based on all 7156 independent reflections with 7156 F > 3σ( F). The crystal structure is based on pentamers consisting of four Si tetrahedra linked by the central Mg tetrahedron. The structure can formally be refined in the cubic space group ( a = 15.105 Å, sp. gr. Fd overline 3 , seven independent positions) with anisotropic displacement parameters to R = 2.74% based on 579 reflections with F > 3σ( F) without accounting for more than 1000 observed reflections, which are inconsistent with the cubic symmetry of the crystal structure.

Hierarchical mutual information for the comparison of hierarchical community structures in complex networks

NASA Astrophysics Data System (ADS)

Perotti, Juan Ignacio; Tessone, Claudio Juan; Caldarelli, Guido

2015-12-01

The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust, and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the hierarchical mutual information, which is a generalization of the traditional mutual information and makes it possible to compare hierarchical partitions and hierarchical community structures. The normalized version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies and on the hierarchical community structure of artificial and empirical networks. Furthermore, the experiments illustrate some of the practical applications of the hierarchical mutual information, namely the comparison of different community detection methods and the study of the consistency, robustness, and temporal evolution of the hierarchical modular structure of networks.

Effects of Cannabis Use on Human Brain Structure in Psychosis: A Systematic Review Combining In Vivo Structural Neuroimaging and Post Mortem Studies

PubMed Central

Rapp, Charlotte; Bugra, Hilal; Riecher-Rössler, Anita; Tamagni, Corinne; Borgwardt, Stefan

2012-01-01

It is unclear yet whether cannabis use is a moderating or causal factor contributing to grey matter alterations in schizophrenia and the development of psychotic symptoms. We therefore systematically reviewed structural brain imaging and post mortem studies addressing the effects of cannabis use on brain structure in psychosis. Studies with schizophrenia (SCZ) and first episode psychosis (FEP) patients as well as individuals at genetic (GHR) or clinical high risk for psychosis (ARMS) were included. We identified 15 structural magnetic resonance imaging (MRI) (12 cross sectional / 3 longitudinal) and 4 post mortem studies. The total number of subjects encompassed 601 schizophrenia or first episode psychosis patients, 255 individuals at clinical or genetic high risk for psychosis and 397 healthy controls. We found evidence for consistent brain structural abnormalities in cannabinoid 1 (CB1) receptor enhanced brain areas as the cingulate and prefrontal cortices and the cerebellum. As these effects have not consistently been reported in studies examining non-psychotic and healthy samples, psychosis patients and subjects at risk for psychosis might be particularly vulnerable to brain volume loss due to cannabis exposure PMID:22716152

Structure of the thermodynamic arrow of time in classical and quantum theories

NASA Astrophysics Data System (ADS)

Korzekwa, Kamil

2017-05-01

In this work we analyze the structure of the thermodynamic arrow of time, defined by transformations that leave the thermal equilibrium state unchanged, in classical (incoherent) and quantum (coherent) regimes. We note that in the infinite-temperature limit, the thermodynamic ordering of states in both regimes exhibits a lattice structure. This means that when energy does not matter and the only thermodynamic resource is given by information, the thermodynamic arrow of time has a very specific structure. Namely, for any two states at present there exists a unique state in the past consistent with them and with all possible joint pasts. Similarly, there also exists a unique state in the future consistent with those states and with all possible joint futures. We also show that the lattice structure in the classical regime is broken at finite temperatures, i.e., when energy is a relevant thermodynamic resource. Surprisingly, however, we prove that in the simplest quantum scenario of a two-dimensional system, this structure is preserved at finite temperatures. We provide the physical interpretation of these results by introducing and analyzing the history erasure process, and point out that quantum coherence may be a necessary resource for the existence of an optimal erasure process.

On the inversion of the 1 Bu and 2 Ag electronic states in α,ω-diphenylpolyenes

NASA Astrophysics Data System (ADS)

Catalán, J.

2003-07-01

An alternative model to that of the inversion of the states 1Bu and 2Ag is proposed for interpreting the photophysics of the α,ω-diphenylpolyenes. This model is based upon the existence of two chemical structures with Bu symmetry, which may be ascribed to the same excited electronic state 1Bu. One of the two chemical structures corresponds to the Franck-Condon structure with conjugated single and double bonds for the polyene chain, and another consists of a nearly equivalent series of partial double bonds along the polyene chain. The latter relaxed structure is consistent with the observation of high torsional energy barriers and low photoisomerization quantum yields for diphenylhexatriene in the singlet excited state manifold. Interestingly, such a simple quantum model as that of the particle in a one-dimensional box provides quite an accurate description of the absorption spectroscopic properties of these major compounds. This is partly the result of the most stable structures for these compounds being of the all-trans type; such structures increase in length as additional ethylene units are added, which makes them very similar to a one-dimensional box becoming increasingly longer.

Right-Handed Helical Foldamers Consisting of De Novo d -AApeptides

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

Teng, Peng; Ma, Ning; Cerrato, Darrell Cole

New types of foldamer scaffolds are formidably challenging to design and synthesize, yet highly desirable as structural mimics of peptides/proteins with a wide repertoire of functions. In particular, the development of peptidomimetic helical foldamers holds promise for new biomaterials, catalysts, and drug molecules. Unnatural l-sulfono-γ-AApeptides were recently developed and shown to have potential applications in both biomedical and material sciences. However, d-sulfono-γ-AApeptides, the enantiomers of l-sulfono-γ-AApeptides, have never been studied due to the lack of high-resolution three-dimensional structures to guide structure-based design. Herein, we report the first synthesis and X-ray crystal structures of a series of 2:1 l-amino acid/d-sulfono-γ-AApeptide hybridmore » foldamers, and elucidate their folded conformation at the atomic level. Single-crystal X-ray crystallography indicates that this class of oligomers folds into well-defined right-handed helices with unique helical parameters. The helical structures were consistent with data obtained from solution 2D NMR, CD studies, and molecular dynamics simulations. Our findings are expected to inspire the structure-based design of this type of unique folding biopolymers for biomaterials and biomedical applications.« less

Worldwide Protein Data Bank biocuration supporting open access to high-quality 3D structural biology data

PubMed Central

Westbrook, John D; Feng, Zukang; Persikova, Irina; Sala, Raul; Sen, Sanchayita; Berrisford, John M; Swaminathan, G Jawahar; Oldfield, Thomas J; Gutmanas, Aleksandras; Igarashi, Reiko; Armstrong, David R; Baskaran, Kumaran; Chen, Li; Chen, Minyu; Clark, Alice R; Di Costanzo, Luigi; Dimitropoulos, Dimitris; Gao, Guanghua; Ghosh, Sutapa; Gore, Swanand; Guranovic, Vladimir; Hendrickx, Pieter M S; Hudson, Brian P; Ikegawa, Yasuyo; Kengaku, Yumiko; Lawson, Catherine L; Liang, Yuhe; Mak, Lora; Mukhopadhyay, Abhik; Narayanan, Buvaneswari; Nishiyama, Kayoko; Patwardhan, Ardan; Sahni, Gaurav; Sanz-García, Eduardo; Sato, Junko; Sekharan, Monica R; Shao, Chenghua; Smart, Oliver S; Tan, Lihua; van Ginkel, Glen; Yang, Huanwang; Zhuravleva, Marina A; Markley, John L; Nakamura, Haruki; Kurisu, Genji; Kleywegt, Gerard J; Velankar, Sameer; Berman, Helen M; Burley, Stephen K

2018-01-01

Abstract The Protein Data Bank (PDB) is the single global repository for experimentally determined 3D structures of biological macromolecules and their complexes with ligands. The worldwide PDB (wwPDB) is the international collaboration that manages the PDB archive according to the FAIR principles: Findability, Accessibility, Interoperability and Reusability. The wwPDB recently developed OneDep, a unified tool for deposition, validation and biocuration of structures of biological macromolecules. All data deposited to the PDB undergo critical review by wwPDB Biocurators. This article outlines the importance of biocuration for structural biology data deposited to the PDB and describes wwPDB biocuration processes and the role of expert Biocurators in sustaining a high-quality archive. Structural data submitted to the PDB are examined for self-consistency, standardized using controlled vocabularies, cross-referenced with other biological data resources and validated for scientific/technical accuracy. We illustrate how biocuration is integral to PDB data archiving, as it facilitates accurate, consistent and comprehensive representation of biological structure data, allowing efficient and effective usage by research scientists, educators, students and the curious public worldwide. Database URL: https://www.wwpdb.org/ PMID:29688351

Phonon dispersions, band structures, and dielectric functions of BeO and BeS polymorphs

NASA Astrophysics Data System (ADS)

Wang, Ke-Long; Gao, Shang-Peng

2018-07-01

Structures, phonon dispersions, electronic structures, and dielectric functions of beryllium oxide (BeO) and beryllium sulfide (BeS) polymorphs are investigated by density functional theory and many-body perturbation theory. Phonon calculations indicate that both wurtzite (w-) and zincblende (zb-) structures are dynamically stable for BeO and BeS, whereas rocksalt (rs-) structures for both BeO and BeS have imaginary phonon frequencies and thus are dynamically unstable at zero pressure. Band structures for the 4 dynamically stable phases show that only w-BeO has a direct band gap. Both the one-shot G0W0 and quasiparticle self-consistent GW methods are used to correct band energies at high symmetry k-points. Bethe-Salpeter equation (BSE), which considers Coulomb correlated electron-hole pairs, is employed to deal with the computation of macroscopic dielectric functions. It is shown that BSE calculation, employing scissors operator derived by self-consistent GW method, can give dielectric functions agreeing very well with experimental measurement of w-BeO. Weak anisotropic characters can be observed for w-BeO and w-BeS. Both zb-BeS and w-BeS show high optical transition probabilities within a narrow ultraviolet energy range.

Long range surface plasmons on asymmetric suspended thin film structures for biosensing applications.

PubMed

Min, Qiao; Chen, Chengkun; Berini, Pierre; Gordon, Reuven

2010-08-30

We show that long-range surface plasmons (LRSPs) are supported in a physically asymmetric thin film structure, consisting of a low refractive index medium on a metal slab, supported by a high refractive index dielectric layer (membrane) over air, as a suspended waveguide. For design purposes, an analytic formulation is derived in 1D yielding a transcendental equation that ensures symmetry of the transverse fields of the LRSP within the metal slab by constraining its thicknesses and that of the membrane. Results from the formulation are in quantitative agreement with transfer matrix calculations for a candidate slab waveguide consisting of an H(2)O-Au-SiO(2)-air structure. Biosensor-relevant figures of merit are compared for the asymmetric and symmetric structures, and it is found that the asymmetric structure actually improves performance, despite higher losses. The finite difference method is also used to analyse metal stripes providing 2D confinement on the structure, and additional constraints for non-radiative LRSP guiding thereon are discussed. These results are promising for sensors that operate with an aqueous solution that would otherwise require a low refractive index-matched substrate for the LRSP.

Mapping the MMPI-2-RF Specific Problems Scales Onto Extant Psychopathology Structures.

PubMed

Sellbom, Martin

2017-01-01

A main objective in developing the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008 ) was to link the hierarchical structure of the instrument's scales to contemporary psychopathology and personality models for greater enhancement of construct validity. Initial evidence published with the Restructured Clinical scales has indicated promising results in that the higher order structure of these measures maps onto those reported in the extant psychopathology literature. This study focused on evaluating the internal structure of the Specific Problems and Interest scales, which have not yet been examined in this manner. Two large, mixed-gender outpatient and correctional samples were used. Exploratory factor analyses revealed consistent evidence for a 4-factor structure representing somatization, negative affect, externalizing, and social detachment. Convergent and discriminant validity analyses in the outpatient sample yielded a pattern of results consistent with expectations. These findings add further evidence to indicate that the MMPI-2-RF hierarchy of scales map onto extant psychopathology literature, and also add support to the notion that somatization and detachment should be considered important higher order domains in the psychopathology literature.

Anisotropy of the nitrogen conduction states in the group III nitrides studied by polarized x-ray absorption

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

Lawniczak-Jablonska, K.; Liliental-Weber, Z.; Gullikson, E.M.

1997-04-01

Group III nitrides (AlN, GaN, and InN) consist of the semiconductors which appear recently as a basic materials for optoelectronic devices active in the visible/ultraviolet spectrum as well as high-temperature and high-power microelectronic devices. However, understanding of the basic physical properties leading to application is still not satisfactory. One of the reasons consists in unsufficient knowledge of the band structure of the considered semiconductors. Several theoretical studies of III-nitrides band structure have been published but relatively few experimental studies have been carried out, particularly with respect to their conduction band structure. This motivated the authors to examine the conduction bandmore » structure projected onto p-states of the nitrogen atoms for AlN, GaN and InN. An additional advantage of their studies is the availability of the studied nitrides in two structures, hexagonal (wurtzite) and cubic (zincblende). This offers an opportunity to gain information about the role of the anisotropy of electronic band states in determining various physical properties.« less

Theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains

NASA Astrophysics Data System (ADS)

Zhu, Ning; Sun, Shou-Guang; Li, Qiang; Zou, Hua

2014-12-01

One of the major problems in structural fatigue life analysis is establishing structural load spectra under actual operating conditions. This study conducts theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains. The quasistatic load series that corresponds to quasi-static deformation modes are identified according to the structural form and bearing conditions of high-speed train bogie frames. Moreover, a force-measuring frame is designed and manufactured based on the quasi-static load series. The load decoupling model of the quasi-static load series is then established via calibration tests. Quasi-static load-time histories, together with online tests and decoupling analysis, are obtained for the intermediate range of the Beijing—Shanghai dedicated passenger line. The damage consistency calibration of the quasi-static discrete load spectra is performed according to a damage consistency criterion and a genetic algorithm. The calibrated damage that corresponds with the quasi-static discrete load spectra satisfies the safety requirements of bogie frames.

One-dimensional rigid film acoustic metamaterials

NASA Astrophysics Data System (ADS)

Ma, Fuyin; Wu, Jiu Hui; Huang, Meng

2015-11-01

We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves.

Structure of Urtica dioica agglutinin isolectin I: dimer formation mediated by two zinc ions bound at the sugar-binding site.

PubMed

Harata, K; Schubert, W D; Muraki, M

2001-11-01

Ultica dioica agglutinin, a plant lectin from the stinging nettle, consists of a total of seven individual isolectins. One of these structures, isolectin I, was determined at 1.9 A resolution by the X-ray method. The crystals belong to the space group P2(1) and the asymmetric unit contains two molecules related by local twofold symmetry. The molecule consists of two hevein-like chitin-binding domains lacking distinct secondary structure, but four disulfide bonds in each domain maintain the tertiary structure. The backbone structure of the two independent molecules is essentially identical and this is similarly true of the sugar-binding sites. In the crystal, the C-terminal domains bind Zn(2+) ions at the sugar-binding site. Owing to their location near a pseudo-twofold axis, the two zinc ions link the two independent molecules in a tail-to-tail arrangement: thus, His47 of molecule 1 and His67 of molecule 2 coordinate the first zinc ion, while the second zinc ion links Asp75 of molecule 1 and His47 of molecule 2.

Synthesis and morphogenesis of organic polymer materials with hierarchical structures in biominerals.

PubMed

Oaki, Yuya; Kijima, Misako; Imai, Hiroaki

2011-06-08

Synthesis and morphogenesis of polypyrrole (PPy) with hierarchical structures from nanoscopic to macroscopic scales have been achieved by using hierarchically organized architectures of biominerals. We adopted biominerals, such as a sea urchin spine and nacreous layer, having hierarchical architectures based on mesocrystals as model materials used for synthesis of an organic polymer. A sea urchin spine led to the formation of PPy macroscopic sponge structures consisting of nanosheets less than 100 nm in thickness with the mosaic interior of the nanoparticles. The morphologies of the resultant PPy hierarchical architectures can be tuned by the structural modification of the original biomineral with chemical and thermal treatments. In another case, a nacreous layer provided PPy porous nanosheets consisting of the nanoparticles. Conductive pathways were formed in these PPy hierarchical architectures. The nanoscale interspaces in the mesocrystal structures of biominerals are used for introduction and polymerization of the monomers, leading to the formation of hierarchically organized polymer architectures. These results show that functional organic materials with complex and nanoscale morphologies can be synthesized by using hierarchically organized architectures as observed in biominerals.

A novel hybrid joining methodology for composite to steel joints

NASA Astrophysics Data System (ADS)

Sarh, Bastian

This research has established a novel approach for designing, analyzing, and fabricating load bearing structural connections between resin infused composite materials and components made of steel or other metals or alloys. A design philosophy is proposed wherein overlapping joint sections comprised of fiber reinforced plastics (FRP's) and steel members are connected via a combination of adhesive bonding and integrally placed composite pins. A film adhesive is utilized, placed into the dry stack prior to resin infusion and is cured after infusion through either local heat elements or by placing the structure into an oven. The novel manner in which the composite pins are introduced consists of perforating the steel member with holes and placing pre-formed composite pins through them, also prior to resin infusion of the composite section. In this manner joints are co-molded structures such that secondary processing is eliminated. It is shown that such joints blend the structural benefits of adhesive and mechanically connected joints, and that the fabrication process is feasible for low-cost, large-scale production as applicable to the shipbuilding industry. Analysis procedures used for designing such joints are presented consisting of an adhesive joint design theory and a pin placement theory. These analysis tools are used in the design of specimens, specific designs are fabricated, and these evaluated through structural tests. Structural tests include quasi-static loading and low cycle fatigue evaluation. This research has thereby invented a novel philosophy on joints, created the manufacturing technique for fabricating such joints, established simple to apply analysis procedures used in the design of such joints (consisting of both an adhesive and a pin placement analysis), and has validated the methodology through specimen fabrication and testing.

Structural Characterization of a Thrombin-Aptamer Complex by High Resolution Native Top-Down Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhang, Jiang; Loo, Rachel R. Ogorzalek; Loo, Joseph A.

2017-09-01

Native mass spectrometry (MS) with electrospray ionization (ESI) has evolved as an invaluable tool for the characterization of intact native proteins and non-covalently bound protein complexes. Here we report the structural characterization by high resolution native top-down MS of human thrombin and its complex with the Bock thrombin binding aptamer (TBA), a 15-nucleotide DNA with high specificity and affinity for thrombin. Accurate mass measurements revealed that the predominant form of native human α-thrombin contains a glycosylation mass of 2205 Da, corresponding to a sialylated symmetric biantennary oligosaccharide structure without fucosylation. Native MS showed that thrombin and TBA predominantly form a 1:1 complex under near physiological conditions (pH 6.8, 200 mM NH4OAc), but the binding stoichiometry is influenced by the solution ionic strength. In 20 mM ammonium acetate solution, up to two TBAs were bound to thrombin, whereas increasing the solution ionic strength destabilized the thrombin-TBA complex and 1 M NH4OAc nearly completely dissociated the complex. This observation is consistent with the mediation of thrombin-aptamer binding through electrostatic interactions and it is further consistent with the human thrombin structure that contains two anion binding sites on the surface. Electron capture dissociation (ECD) top-down MS of the thrombin-TBA complex performed with a high resolution 15 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer showed the primary binding site to be at exosite I located near the N-terminal sequence of the heavy chain, consistent with crystallographic data. High resolution native top-down MS is complementary to traditional structural biology methods for structurally characterizing native proteins and protein-DNA complexes. [Figure not available: see fulltext.

AN INVESTIGATION OF TIME LAG MAPS USING THREE-DIMENSIONAL SIMULATIONS OF HIGHLY STRATIFIED HEATING

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

Winebarger, Amy R.; Lionello, Roberto; Downs, Cooper

2016-11-10

The location and frequency of coronal energy release provide a significant constraint on the coronal heating mechanism. The evolution of the intensity observed in coronal structures found from time lag analysis of Atmospheric Imaging Assembly (AIA) data has been used to argue that heating must occur sporadically. Recently, we have demonstrated that quasi-steady, highly stratified (footpoint) heating can produce results qualitatively consistent with the evolution of observed coronal structures. The goals of this paper are to demonstrate that time lag analysis of 3D simulations of footpoint heating are qualitatively consistent with time lag analysis of observations and to use themore » 3D simulations to further understand whether time lag analysis is a useful tool in defining the evolution of coronal structures. We find the time lag maps generated from simulated data are consistent with the observed time lag maps. We next investigate several example points. In some cases, the calculated time lag reflects the evolution of a unique loop along the line of sight, though there may be additional evolving structures along the line of sight. We confirm that using the multi-peak AIA channels can produce time lags that are difficult to interpret. We suggest using a different high temperature channel, such as an X-ray channel. Finally, we find that multiple evolving structures along the line of sight can produce time lags that do not represent the physical properties of any structure along the line of sight, although the cross-correlation coefficient of the lightcurves is high. Considering the projected geometry of the loops may reduce some of the line-of-sight confusion.« less

Plasmonic detection of possible defects in multilayer nanohole array consisting of essential materials in simplified STT-RAM cell

NASA Astrophysics Data System (ADS)

Sadri-Moshkenani, Parinaz; Khan, Mohammad Wahiduzzaman; Zhao, Qiancheng; Krivorotov, Ilya; Nilsson, Mikael; Bagherzadeh, Nader; Boyraz, Ozdal

2017-08-01

Plasmonic nanostructures are highly used for sensing purposes since they support plasmonic modes which make them highly sensitive to the refractive index change of their surrounding medium. Therefore, they can also be used to detect changes in optical properties of ultrathin layer films in a multilayer plasmonic structure. Here, we investigate the changes in optical properties of ultrathin films of macro structures consisting of STT-RAM layers. Among the highest sensitive plasmonic structures, nanohole array has attracted many research interest because of its ease of fabrication, small footprint, and simplified optical alignment. Hence it is more suitable for defect detection in STT-RAM geometries. Moreover, the periodic nanohole pattern in the nanohole array structure makes it possible to couple the light to the surface plasmon polariton (SPP) mode supported by the structure. To assess the radiation damages and defects in STT-RAM cells we have designed a multilayer nanohole array based on the layers used in STT-RAM structure, consisting 4nm- Ta/1.5nm-CoFeB/2nm-MgO/1.5nm-CoFeB/4nm-Ta layers, all on a 300nm silver layer on top of a PEC boundary. The nanoholes go through all the layers and become closed by the PEC boundary on one side. The dimensions of the designed nanoholes are 313nm depth, 350nm diameter, and 700nm period. Here, we consider the normal incidence of light and investigate zeroth-order reflection coefficient to observe the resonance. Our simulation results show that a 10% change in refractive index of the 2nm-thick MgO layer leads to about 122GHz shift in SPP resonance in reflection pattern.

A cytochemical and radioautographic study of the ultrastructural organization of puff-like fibrillar structures in plant interphase nuclei (Allium porrum).

PubMed

Lafontaine, J G; Luck, B T; Dontigny, D

1979-10-01

Loose, fibrillar, spherical structures have been observed during recent years in interphase nuclei of both animal and plant cells. These nuclear formations have been referred to as karyosomes, fibrillar bodies, micropuffs and centromeres. In order to gain further information on the nature of these structures, a cytochemical and radioautographic investigation was undertaken using plant meristematic cells (Allium porrum). For that purpose roots were fixed with either formaldehyde or glutaraldehyde in order to carry out cytochemical tests for DNA, RNA and proteins. Certain of the preparations were also first digested with DNase, RNase or proteinase K and then stained according to different procedures. Other specimens were labelled with thymidine for high-resolution radioautographic observations. Staining with diaminobenzidine (DAB) revealed that these nuclear puff-like formations consisted partly of a loose fibrillar meshwork containing nucleic acids. Part of this fine fibrillar reticulum persisted whether the preparations were digested with DNase or RNase before staining with DAB, thus indicating that these nuclear structures contained both DNA and RNA. The fact that these formations incorporate thymidine furnished additional support for the view that they correspond to specific chromosome segments. Staining with ethanolic phosphotungstic acid or digestion of specimens with proteinase K showed that these loose fibrillar structures also consisted of proteins. Judging from their ultrastructure, their association with the chromatin reticulum as well as from their cytochemical characteristics, these nuclear formations most likely correspond to centromeres. In view of the presence of DNA within these structures, it is possible to distinguish them from other equally spherical nuclear formations, observed in certain plant species, that have generally been referred to as karyosomes or micronucleoli and that appear to consist of ribonucleoproteins.

Crystal structure across the β to α phase transition in thermoelectric Cu 2–xSe

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

Eikeland, Espen; Blichfeld, Anders B.; Borup, Kasper A.

Here, the crystal structure uniquely imparts the specific properties of a material, and thus provides the starting point for any quantitative understanding of thermoelectric properties. Cu 2–xSe is an intensely studied high performing, non-toxic and cheap thermoelectric material, and here for the first time, the average structure of β-Cu 2–xSe is reported based on analysis of multi-temperature single-crystal X-ray diffraction data. It consists of Se–Cu layers with additional copper between every alternate layer. The structural changes during the peculiar zT enhancing phase transition mainly consist of changes in the inter-layer distance coupled with subtle Cu migration. Just prior to themore » transition the structure exhibits strong negative thermal expansion due to the reordering of Cu atoms, when approached from low temperatures. The phase transition is fully reversible and group–subgroup symmetry relations are derived that relate the low-temperature β-phase to the high-temperature α-phase. Weak superstructure reflections are observed and a possible Cu ordering is proposed. The structural rearrangement may have a significant impact on the band structure and the Cu rearrangement may also be linked to an entropy increase. Both factors potentially contribute to the extraordinary zT enhancement across the phase transition.« less

Crystal structure across the β to α phase transition in thermoelectric Cu 2–xSe

DOE PAGES

Eikeland, Espen; Blichfeld, Anders B.; Borup, Kasper A.; ...

2017-06-13

Here, the crystal structure uniquely imparts the specific properties of a material, and thus provides the starting point for any quantitative understanding of thermoelectric properties. Cu 2–xSe is an intensely studied high performing, non-toxic and cheap thermoelectric material, and here for the first time, the average structure of β-Cu 2–xSe is reported based on analysis of multi-temperature single-crystal X-ray diffraction data. It consists of Se–Cu layers with additional copper between every alternate layer. The structural changes during the peculiar zT enhancing phase transition mainly consist of changes in the inter-layer distance coupled with subtle Cu migration. Just prior to themore » transition the structure exhibits strong negative thermal expansion due to the reordering of Cu atoms, when approached from low temperatures. The phase transition is fully reversible and group–subgroup symmetry relations are derived that relate the low-temperature β-phase to the high-temperature α-phase. Weak superstructure reflections are observed and a possible Cu ordering is proposed. The structural rearrangement may have a significant impact on the band structure and the Cu rearrangement may also be linked to an entropy increase. Both factors potentially contribute to the extraordinary zT enhancement across the phase transition.« less

pE-DB: a database of structural ensembles of intrinsically disordered and of unfolded proteins.

PubMed

Varadi, Mihaly; Kosol, Simone; Lebrun, Pierre; Valentini, Erica; Blackledge, Martin; Dunker, A Keith; Felli, Isabella C; Forman-Kay, Julie D; Kriwacki, Richard W; Pierattelli, Roberta; Sussman, Joel; Svergun, Dmitri I; Uversky, Vladimir N; Vendruscolo, Michele; Wishart, David; Wright, Peter E; Tompa, Peter

2014-01-01

The goal of pE-DB (http://pedb.vib.be) is to serve as an openly accessible database for the deposition of structural ensembles of intrinsically disordered proteins (IDPs) and of denatured proteins based on nuclear magnetic resonance spectroscopy, small-angle X-ray scattering and other data measured in solution. Owing to the inherent flexibility of IDPs, solution techniques are particularly appropriate for characterizing their biophysical properties, and structural ensembles in agreement with these data provide a convenient tool for describing the underlying conformational sampling. Database entries consist of (i) primary experimental data with descriptions of the acquisition methods and algorithms used for the ensemble calculations, and (ii) the structural ensembles consistent with these data, provided as a set of models in a Protein Data Bank format. PE-DB is open for submissions from the community, and is intended as a forum for disseminating the structural ensembles and the methodologies used to generate them. While the need to represent the IDP structures is clear, methods for determining and evaluating the structural ensembles are still evolving. The availability of the pE-DB database is expected to promote the development of new modeling methods and leads to a better understanding of how function arises from disordered states.

Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro

PubMed Central

Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

2015-01-01

In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

Cosmological consistency tests of gravity theory and cosmic acceleration

NASA Astrophysics Data System (ADS)

Ishak-Boushaki, Mustapha B.

2017-01-01

Testing general relativity at cosmological scales and probing the cause of cosmic acceleration are among the important objectives targeted by incoming and future astronomical surveys and experiments. I present our recent results on consistency tests that can provide insights about the underlying gravity theory and cosmic acceleration using cosmological data sets. We use statistical measures, the rate of cosmic expansion, the growth rate of large scale structure, and the physical consistency of these probes with one another.

A quantitative meta-analysis and review of motor learning in the human brain

PubMed Central

Hardwick, Robert M.; Rottschy, Claudia; Miall, R. Chris; Eickhoff, Simon B.

2013-01-01

Neuroimaging studies have improved our understanding of which brain structures are involved in motor learning. Despite this, questions remain regarding the areas that contribute consistently across paradigms with different task demands. For instance, sensorimotor tasks focus on learning novel movement kinematics and dynamics, while serial response time task (SRTT) variants focus on sequence learning. These differing task demands are likely to elicit quantifiably different patterns of neural activity on top of a potentially consistent core network. The current study identified consistent activations across 70 motor learning experiments using activation likelihood estimation (ALE) meta-analysis. A global analysis of all tasks revealed a bilateral cortical–subcortical network consistently underlying motor learning across tasks. Converging activations were revealed in the dorsal premotor cortex, supplementary motor cortex, primary motor cortex, primary somatosensory cortex, superior parietal lobule, thalamus, putamen and cerebellum. These activations were broadly consistent across task specific analyses that separated sensorimotor tasks and SRTT variants. Contrast analysis indicated that activity in the basal ganglia and cerebellum was significantly stronger for sensorimotor tasks, while activity in cortical structures and the thalamus was significantly stronger for SRTT variants. Additional conjunction analyses then indicated that the left dorsal premotor cortex was activated across all analyses considered, even when controlling for potential motor confounds. The highly consistent activation of the left dorsal premotor cortex suggests it is a critical node in the motor learning network. PMID:23194819

X-Ray Absorption near Edge Structure Spectroscopy of Nanodiamonds from the Allende Meteorite

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Keller, L. P.; Hill, H.; Jacobsen, C.; Wirick, S.

2000-01-01

Carbon X-ray Absorption Near Edge Structure Spectroscopy shows Allende DM nanodiamonds have two pre-edge peaks, consistent with other small diamonds, but fail to show a diamond exciton which is seen in 3.6 nm diamond thin films.

29 CFR 1917.118 - Fixed ladders.

Code of Federal Regulations, 2011 CFR

2011-07-01

... bolts or structural members of tanks and towers; (3) Ladders built into or vertically attached to..., microwave communications, electrical power and similar towers, poles and structures, including stacks and... consisting of individual rungs that are attached to walls, conical manhole sections or river cells shall: (1...

29 CFR 1917.118 - Fixed ladders.

Code of Federal Regulations, 2010 CFR

2010-07-01

... bolts or structural members of tanks and towers; (3) Ladders built into or vertically attached to..., microwave communications, electrical power and similar towers, poles and structures, including stacks and... consisting of individual rungs that are attached to walls, conical manhole sections or river cells shall: (1...

Relational Algebra and SQL: Better Together

ERIC Educational Resources Information Center

McMaster, Kirby; Sambasivam, Samuel; Hadfield, Steven; Wolthuis, Stuart

2013-01-01

In this paper, we describe how database instructors can teach Relational Algebra and Structured Query Language together through programming. Students write query programs consisting of sequences of Relational Algebra operations vs. Structured Query Language SELECT statements. The query programs can then be run interactively, allowing students to…

Tank waste remediation system immobilized high-level waste storage project configuration management implementation plan

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

Burgard, K.G.

This Configuration Management Implementation Plan was developed to assist in the management of systems, structures, and components, to facilitate the effective control and statusing of changes to systems, structures, and components; and to ensure technical consistency between design, performance, and operational requirements. Its purpose is to describe the approach Project W-464 will take in implementing a configuration management control, to determine the rigor of control, and to identify the mechanisms for imposing that control.This Configuration Management Implementation Plan was developed to assist in the management of systems, structures, and components, to facilitate the effective control and statusing of changes tomore » systems, structures, and components; and to ensure technical consistency between design, performance, and operational requirements. Its purpose is to describe the approach Project W-464 will take in implementing a configuration management control, to determine the rigor of control, and to identify the mechanisms for imposing that control.« less

Remote online monitoring and measuring system for civil engineering structures

NASA Astrophysics Data System (ADS)

Kujawińska, Malgorzata; Sitnik, Robert; Dymny, Grzegorz; Karaszewski, Maciej; Michoński, Kuba; Krzesłowski, Jakub; Mularczyk, Krzysztof; Bolewicki, Paweł

2009-06-01

In this paper a distributed intelligent system for civil engineering structures on-line measurement, remote monitoring, and data archiving is presented. The system consists of a set of optical, full-field displacement sensors connected to a controlling server. The server conducts measurements according to a list of scheduled tasks and stores the primary data or initial results in a remote centralized database. Simultaneously the server performs checks, ordered by the operator, which may in turn result with an alert or a specific action. The structure of whole system is analyzed along with the discussion on possible fields of application and the ways to provide a relevant security during data transport. Finally, a working implementation consisting of a fringe projection, geometrical moiré, digital image correlation and grating interferometry sensors and Oracle XE database is presented. The results from database utilized for on-line monitoring of a threshold value of strain for an exemplary area of interest at the engineering structure are presented and discussed.

Structural rigidity in the capsid assembly of cowpea chlorotic mottle virus

NASA Astrophysics Data System (ADS)

Hespenheide, B. M.; Jacobs, D. J.; Thorpe, M. F.

2004-11-01

The cowpea chlorotic mottle virus (CCMV) has a protein cage, or capsid, which encloses its genetic material. The structure of the capsid consists of 180 copies of a single protein that self-assemble inside a cell to form a complete capsid with icosahedral symmetry. The icosahedral surface can be naturally divided into pentagonal and hexagonal faces, and the formation of either of these faces has been proposed to be the first step in the capsid assembly process. We have used the software FIRST to analyse the rigidity of pentameric and hexameric substructures of the complete capsid to explore the viability of certain capsid assembly pathways. FIRST uses the 3D pebble game to determine structural rigidity, and a brief description of this algorithm, as applied to body-bar networks, is given here. We find that the pentameric substructure, which corresponds to a pentagonal face on the icosahedral surface, provides the best structural properties for nucleating the capsid assembly process, consistent with experimental observations.

Influence of the extraction process on the rheological and structural properties of agars.

PubMed

Sousa, Ana M M; Borges, João; Silva, A Fernando; Gonçalves, Maria P

2013-07-01

Agars obtained by traditional hot-water (TWE) and microwave-assisted (MAE) extractions were compared in terms of their rheological and physicochemical properties and molecular self-association in solutions of low (0.05%, w/w) and high (1.5%, w/w) polymer concentrations. At low concentration, thin gelled layers were imaged by AFM. Slow or rapid cooling of the solutions influenced structure formation. In each case, TWE and MAE agar structures were different and apparently larger for MAE. At high concentration, progressive structural reinforcement was seen; while TWE agar showed a more open and irregular 3D network, MAE agar gel imaged by cryoSEM was denser and fairly uniform. The rheological (higher thermal stability and consistency) and mechanical (higher gel strength) behaviors of MAE agar seemed consistent with a positive effect of molecular mass and 3,6-anhydro-α-l-galactose content. MAE produced non-degraded agar comparable with commercial ones and if properly monitored, could be a promising alternative to TWE. Copyright © 2013 Elsevier Ltd. All rights reserved.

Structural and Immunological Activity Characterization of a Polysaccharide Isolated from Meretrix meretrix Linnaeus

PubMed Central

Li, Li; Li, Heng; Qian, Jianying; He, Yongfeng; Zheng, Jialin; Lu, Zhenming; Xu, Zhenghong; Shi, Jinsong

2015-01-01

Polysaccharides from marine clams perform various biological activities, whereas information on structure is scarce. Here, a water-soluble polysaccharide MMPX-B2 was isolated from Meretrix meretrix Linnaeus. The proposed structure was deduced through characterization and its immunological activity was investigated. MMPX-B2 consisted of d-glucose and d-galctose residues at a molar ratio of 3.51:1.00. The average molecular weight of MMPX-B2 was 510 kDa. This polysaccharide possessed a main chain of (1→4)-linked-α-d-glucopyranosyl residues, partially substituted at the C-6 position by a few terminal β-d-galactose residues or branched chains consisting of (1→3)-linked β-d-galactose residues. Preliminary immunological tests in vitro showed that MMPX-B2 could stimulate the murine macrophages to release various cytokines, and the structure-activity relationship was then established. The present study demonstrated the potential immunological activity of MMPX-B2, and provided references for studying the active ingredients in M. meretrix. PMID:26729136

General Mechanism of Two-State Protein Folding Kinetics

PubMed Central

Rollins, Geoffrey C.; Dill, Ken A.

2016-01-01

We describe here a general model of the kinetic mechanism of protein folding. In the Foldon Funnel Model, proteins fold in units of secondary structures, which form sequentially along the folding pathway, stabilized by tertiary interactions. The model predicts that the free energy landscape has a volcano shape, rather than a simple funnel, that folding is two-state (single-exponential) when secondary structures are intrinsically unstable, and that each structure along the folding path is a transition state for the previous structure. It shows how sequential pathways are consistent with multiple stochastic routes on funnel landscapes, and it gives good agreement with the 9 order of magnitude dependence of folding rates on protein size for a set of 93 proteins, at the same time it is consistent with the near independence of folding equilibrium constant on size. This model gives estimates of folding rates of proteomes, leading to a median folding time in Escherichia coli of about 5 s. PMID:25056406

Observations of disconnection of open coronal magnetic structures

NASA Technical Reports Server (NTRS)

Mccomas, D. J.; Phillips, J. L.; Hundhausen, A. J.; Burkepile, J. T.

1991-01-01

The solar maximum mission coronagraph/polarimeter observations are surveyed for evidence of magnetic disconnection of previously open magnetic structures and several sequences of images consistent with this interpretation are identified. Such disconnection occurs when open field lines above helmet streamers reconnect, in contrast to previously suggested disconnections of CMEs into closed plasmoids. In this paper a clear example of open field disconnection is shown in detail. The event, on June 27, 1988, is preceded by compression of a preexisting helmet streamer and the open coronal field around it. The compressed helmet streamer and surrounding open field region detach in a large U-shaped structure which subsequently accelerates outward from the sun. The observed sequence of events is consistent with reconnection across the heliospheric current sheet and the creation of a detached U-shaped magnetic structure. Unlike CMEs, which may open new magnetic flux into interplanetary space, this process could serve to close off previously open flux, perhaps helping to maintain the roughly constant amount of open magnetic flux observed in interplanetary space.

Optical Coating Performance and Thermal Structure Design for Heat Reflectors of JWST Electronic Control Unit

NASA Technical Reports Server (NTRS)

Quijada, Manuel A.; Threat, Felix; Garrison, Matt; Perrygo, Chuck; Bousquet, Robert; Rashford, Robert

2008-01-01

The James Webb Space Telescope (JWST) consists of an infrared-optimized Optical Telescope Element (OTE) that is cooled down to 40 degrees Kelvin. A second adjacent component to the OTE is the Integrated Science Instrument Module, or ISIM. This module includes the electronic compartment, which provides the mounting surfaces and ambient thermally controlled environment for the instrument control electronics. Dissipating the 200 watts generated from the ISIM structure away from the OTE is of paramount importance so that the spacecraft's own heat does not interfere with the infrared light detected from distant cosmic sources. This technical challenge is overcome by a thermal subsystem unit that provides passive cooling to the ISIM control electronics. The proposed design of this thermal radiator consists of a lightweight structure made out of composite materials and low-emittance metal coatings. In this paper, we will present characterizations of the coating emittance, bidirectional reflectance, and mechanical structure design that will affect the performance of this passive cooling system.

Multiscale Characterization of Engineered Cardiac Tissue Architecture.

PubMed

Drew, Nancy K; Johnsen, Nicholas E; Core, Jason Q; Grosberg, Anna

2016-11-01

In a properly contracting cardiac muscle, many different subcellular structures are organized into an intricate architecture. While it has been observed that this organization is altered in pathological conditions, the relationship between length-scales and architecture has not been properly explored. In this work, we utilize a variety of architecture metrics to quantify organization and consistency of single structures over multiple scales, from subcellular to tissue scale as well as correlation of organization of multiple structures. Specifically, as the best way to characterize cardiac tissues, we chose the orientational and co-orientational order parameters (COOPs). Similarly, neonatal rat ventricular myocytes were selected for their consistent architectural behavior. The engineered cells and tissues were stained for four architectural structures: actin, tubulin, sarcomeric z-lines, and nuclei. We applied the orientational metrics to cardiac cells of various shapes, isotropic cardiac tissues, and anisotropic globally aligned tissues. With these novel tools, we discovered: (1) the relationship between cellular shape and consistency of self-assembly; (2) the length-scales at which unguided tissues self-organize; and (3) the correlation or lack thereof between organization of actin fibrils, sarcomeric z-lines, tubulin fibrils, and nuclei. All of these together elucidate some of the current mysteries in the relationship between force production and architecture, while raising more questions about the effect of guidance cues on self-assembly function. These types of metrics are the future of quantitative tissue engineering in cardiovascular biomechanics.

Photogeological analysis of Europan tectonic features

NASA Technical Reports Server (NTRS)

Tufts, B. R.

1993-01-01

Preliminary photogeological analyses of the Pelorus Linea and Sidon Flexus regions of Europa were conducted to explore the proposal by Schenk that lateral motion of crustal blocks has occurred in a 'rift zone' including possible strike-slip, tension fracturing, and geometric plate rotation about an Euler pole. These analyses revealed features interpreted as tensional structures and block rotation in a strike-slip regime consistent with the Schenk hypotheses and implied the presence of at least two stages of crustal deformation consistent with a chronology developed by Lucchitta. Confirmation of regional scale Euler pole rotation was ambiguous, however. Up to 80 kilometers of possible extension was identified in the rift zone; to accommodate this, 'cryosubduction' is speculatively proposed as a mechanism for recycling Europan 'ice lithosphere'. The cumulative width of wedge-shaped bands included in the rift zone was measured and plotted versus distance from the inferred rotation pole. Three sharp decreases in the total width were noted. These occur roughly where certain triple bands cross the rift zone suggesting that the bands are structural features that predate and influence the zone. While the curve hints at one or more sinusoidal relationships consistent with rotation geometry, given the low photographic resolution and the preliminary nature of this examination the question of whether the observations represent coherent regional rotation modified by crosscutting structures or instead imply independent local rotations separated by these structures is unanswered by this analysis.

Multi-link piezoelectric structure for vibration energy harvesting

NASA Astrophysics Data System (ADS)

Aryanpur, Rameen M.; White, Robert D.

2012-04-01

Work in piezoelectric vibration energy harvesting has typically focused on single member cantilevered structures with transverse tip displacement at a known frequency, taking advantage of the optimal coupling characteristics of piezoceramics in the 3-1 bending mode. Multi-member designs could be advantageous in delivering power to a load in environments with random or wide-band vibrations. The design presented in this work consists of two hinged piezoceramic (PZT-5A) beams x-poled for series operation. Each beam measures 31.8mm x 12.7mm x 0.38mm and consists of two layers of nickel-plated piezoceramic adhered to a brass center shim. The hinge device consists of two custom-machined aluminum attachments epoxied to the end of a beam and connected using a 1.59mm diameter alloy steel dowel. A stainless steel torsion spring is placed over the pin and attached to the aluminum body to provide a restoring torque when under rotation. The design is modeled using the piezoelectric constitutive equations to solve for voltage and power for a set of electromechanical boundary conditions. Experimental measurements on the design are achieved by bolting one end of the structure to a vibration shaker and fixing the other to a rigid framework of industrial aluminum framing material. For a given frequency of vibration, power output of the structure can be obtained by measuring voltage drop across a resistive load.

Facebook Activities and the Investment of L2 Learners

ERIC Educational Resources Information Center

Shafie, Latisha Asmaak; Yaacob, Aizan; Singh, Paramjit Kaur Karpal

2016-01-01

The article discusses the investment of L2 learners in the English language on Facebook that they portrayed through their Facebook activities. It studied four informants consisted of diploma students in a Malaysian university. The study consisted of 14 weeks of online observation and semi-structured interviews. Data were collected from online…

Study on the Validity and Reliability of Melbourne Decision Making Scale in Turkey

ERIC Educational Resources Information Center

Çolakkadioglu, Oguzhan; Deniz, M. Engin

2015-01-01

This study is to analyze the validity and reliability of Melbourne Decision Making Questionnaire (MDMQ). The sample consisted of 650 university students. The structural validity of the MDMQ, as well as correlations among its sub-scales, measure-bound validity, internal consistency, item total correlations and test-retest reliability coefficients…

Effects of Solar Heating by Aerosols and Trace Gases on the Temperature Structure Constant

DTIC Science & Technology

1990-08-09

stratosphere. Thermosonde measurements taken in Hawaii at a time when the Kilauea volcano was active are consistent with larger diurnal variations beginning...instabilities. Again, this is consistent with the larger diurnal variations of C7n as measured by the thermosonde in Hawaii where the variations were larger and

Career Adapt-Abilities Scale-France Form: Psychometric Properties and Relationships to Anxiety and Motivation

ERIC Educational Resources Information Center

Pouyaud, Jacques; Vignoli, Emmanuelle; Dosnon, Odile; Lallemand, Noelle

2012-01-01

The CAAS-France Form consists of four scales, each with six items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. Internal consistency estimates for the subscale and total scores ranged from moderate to good. The factor structure was…

Self consistent solution of Schrödinger Poisson equations and some electronic properties of ZnMgO/ZnO hetero structures

NASA Astrophysics Data System (ADS)

Uslu, Salih; Yarar, Zeki

2017-02-01

The epitaxial growth of quantum wells composed of high quality allows the production and application to their device of new structures in low dimensions. The potential profile at the junction is determined by free carriers and by the level of doping. Therefore, the shape of potential is obtained by the electron density. Energy level determines the number of electrons that can be occupied at every level. Energy levels and electron density values of each level must be calculated self consistently. Starting with V(z) test potential, wave functions and electron densities for each energy levels can be calculated to solve Schrödinger equation. If Poisson's equation is solved with the calculated electron density, the electrostatic potential can be obtained. The new V(z) potential can be calculated with using electrostatic potential found beforehand. Thus, the obtained values are calculated self consistently to a certain error criterion. In this study, the energy levels formed in the interfacial potential, electron density in each level and the wave function dependence of material parameters were investigated self consistently.

Factor Structure, Internal Consistency, and Screening Sensitivity of the GARS-2 in a Developmental Disabilities Sample

PubMed Central

Volker, Martin A.; Dua, Elissa H.; Lopata, Christopher; Thomeer, Marcus L.; Toomey, Jennifer A.; Smerbeck, Audrey M.; Rodgers, Jonathan D.; Popkin, Joshua R.; Nelson, Andrew T.; Lee, Gloria K.

2016-01-01

The Gilliam Autism Rating Scale-Second Edition (GARS-2) is a widely used screening instrument that assists in the identification and diagnosis of autism. The purpose of this study was to examine the factor structure, internal consistency, and screening sensitivity of the GARS-2 using ratings from special education teaching staff for a sample of 240 individuals with autism or other significant developmental disabilities. Exploratory factor analysis yielded a correlated three-factor solution similar to that found in 2005 by Lecavalier for the original GARS. Though the three factors appeared to be reasonably consistent with the intended constructs of the three GARS-2 subscales, the analysis indicated that more than a third of the GARS-2 items were assigned to the wrong subscale. Internal consistency estimates met or exceeded standards for screening and were generally higher than those in previous studies. Screening sensitivity was .65 and specificity was .81 for the Autism Index using a cut score of 85. Based on these findings, recommendations are made for instrument revision. PMID:26981279

Microstructure of Desmanthus illinoensis

NASA Astrophysics Data System (ADS)

Wood, Delilah F.; Orts, William J.; Glenn, Gregory M.

2010-06-01

Structure and histochemistry of mature seeds of Desmanthus illinoensis (Illinois bundle flower) show that the seed has typical legume structure. The seed can be separated into two major fractions including the seed coat/endosperm and the embryo. The seed coat consists of a cuticle, palisade sclereids, hour glass cells and mesophyll. Endosperm is attached to the inner portion of the seed coat and is thicker beneath the pleurogram in the center of the seed. The embryo consists mostly of two large cotyledons, the major storage structures of the seed. The cotyledons are high in protein which occurs in protein bodies. Protein bodies in the cotyledons include those without inclusions, those with phytin inclusions and those with calcium-rich crystals. The phytin inclusions are spherical and have high phosphorus and magnesium contents. The calcium-rich crystals are also included inside protein bodies and are druse-type crystals.

Spin dynamics in the stripe-ordered buckled honeycomb lattice antiferromagnet Ba 2 NiTeO 6

DOE PAGES

Asai, Shinichiro; Soda, Minoru; Kasatani, Kazuhiro; ...

2017-09-01

We carried out inelastic neutron scattering experiments on a buckled honeycomb lattice antiferromagnet Ba 2NiTeO 6 exhibiting a stripe structure at a low temperature. Magnetic excitations are observed in the energy range of ℏω≲10 meV having an anisotropy gap of 2 meV at 2 K. We perform spin-wave calculations to identify the spin model. The obtained microscopic parameters are consistent with the location of the stripe structure in the classical phase diagram. Furthermore, the Weiss temperature independently estimated from a bulk magnetic susceptibility is consistent with the microscopic parameters. The results reveal that a competition between the nearest-neighbor and next-nearest-neighbormore » interactions that together with a relatively large single-ion magnetic anisotropy stabilize the stripe magnetic structure.« less

Felder-Soloman's Index of Learning Styles: internal consistency, temporal stability, and factor structure.

PubMed

Hosford, Charles C; Siders, William A

2010-10-01

Strategies to facilitate learning include using knowledge of students' learning style preferences to inform students and their teachers. Aims of this study were to evaluate the factor structure, internal consistency, and temporal stability of medical student responses to the Index of Learning Styles (ILS) and determine its appropriateness as an instrument for medical education. The ILS assesses preferences on four dimensions: sensing/intuitive information perceiving, visual/verbal information receiving, active/reflective information processing, and sequential/global information understanding. Students entering the 2002-2007 classes completed the ILS; some completed the ILS again after 2 and 4 years. Analyses of responses supported the ILS's intended structure and moderate reliability. Students had moderate preferences for sensing and visual learning. This study provides evidence supporting the appropriateness of the ILS for assessing learning style preferences in medical students.

Cryogenic Insulation System

NASA Technical Reports Server (NTRS)

Davis, Randall C. (Inventor); Taylor, Allan H. (Inventor); Jackson, L. Robert (Inventor); Mcauliffe, Patrick S. (Inventor)

1988-01-01

This invention relates to reusable, low density, high temperature cryogenic foam insulation systems and the process for their manufacture. A pacing technology for liquid hydrogen fueled, high speed aircraft is the development of a fully reusable, flight weight cryogenic insulation system for propellant tank structures. In the invention cryogenic foam insulation is adhesively bonded to the outer wall of the fuel tank structure. The cryogenic insulation consists of square sheets fabricated from an array of abutting square blocks. Each block consists of a sheet of glass cloth adhesively bonded between two layers of polymethacrylimide foam. Each block is wrapped in a vapor impermeable membrane, such as Kapton(R) aluminum Kapton(R), to provide a vapor barrier. Very beneficial results can be obtained by employing the present invention in conjunction with fibrous insulation and an outer aeroshell, a hot fuselage structure with an internal thermal protection system.

The Skin Picking Impact Scale: Factor structure, validity and development of a short version.

PubMed

Snorrason, Ivar; Olafsson, Ragnar P; Flessner, Christopher A; Keuthen, Nancy J; Franklin, Martin E; Woods, Douglas W

2013-08-01

In the present study, we examined the psychometric properties of the Skin Picking Impact Scale (SPIS; Keuthen, Deckersbach, Wilhelm et al., 2001), a 10 item self-report questionnaire designed to assess the psychosocial impact of skin picking disorder (SPD). Participants were 650 individuals who met criteria for SPD in an online survey. Exploratory and confirmatory factor analyses demonstrated a unitary factor structure with high internal consistency (α = 0.94). Consequently, we constructed an abbreviated 4-item version that retained good internal consistency (α = 0.87) and a robust factor structure. Both the short and the full versions demonstrated discriminant and convergent/concurrent validity. In conclusion, the findings indicate that both versions are psychometrically sound measures of SPD related psychosocial impact; however, some potential limitations of the full scale are discussed. © 2013 The Scandinavian Psychological Associations.

Modelling multimedia teleservices with OSI upper layers framework: Short paper

NASA Astrophysics Data System (ADS)

Widya, I.; Vanrijssen, E.; Michiels, E.

The paper presents the use of the concepts and modelling principles of the Open Systems Interconnection (OSI) upper layers structure in the modelling of multimedia teleservices. It puts emphasis on the revised Application Layer Structure (OSI/ALS). OSI/ALS is an object based reference model which intends to coordinate the development of application oriented services and protocols in a consistent and modular way. It enables the rapid deployment and integrated use of these services. The paper emphasizes further on the nesting structure defined in OSI/ALS which allows the design of scalable and user tailorable/controllable teleservices. OSI/ALS consistent teleservices are moreover implementable on communication platforms of different capabilities. An analysis of distributed multimedia architectures which can be found in the literature, confirms the ability of the OSI/ALS framework to model the interworking functionalities of teleservices.

Development of Rene' 41 honeycomb structure as an integral cryogenic tankage/fuselage concept for future space transportation systems

NASA Technical Reports Server (NTRS)

Shideler, J. J.; Swegle, A. R.; Fields, R. A.

1982-01-01

The status of the structural development of an integral cryogenic-tankage/hot-fuselage concept for future space transportation systems (STS) is discussed. The concept consists of a honeycomb sandwich structure which serves the combined functions of containment of cryogenic fuel, support of vehicle loads, and thermal protection from an entry heating environment. The inner face sheet is exposed to a cryogenic (LH2) temperature of -423 F during boost; and the outer face sheet, which is slotted to reduce thermal stress, is exposed to a maximum temperature of 1400 F during a high altitude, gliding entry. A fabrication process for a Rene' 41 honeycomb sandwich panel with a core density less than 1 percent was developed which is consistent with desirable heat treatment processes for high strength.

Spin dynamics in the stripe-ordered buckled honeycomb lattice antiferromagnet Ba 2 NiTeO 6

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

Asai, Shinichiro; Soda, Minoru; Kasatani, Kazuhiro

We carried out inelastic neutron scattering experiments on a buckled honeycomb lattice antiferromagnet Ba 2NiTeO 6 exhibiting a stripe structure at a low temperature. Magnetic excitations are observed in the energy range of ℏω≲10 meV having an anisotropy gap of 2 meV at 2 K. We perform spin-wave calculations to identify the spin model. The obtained microscopic parameters are consistent with the location of the stripe structure in the classical phase diagram. Furthermore, the Weiss temperature independently estimated from a bulk magnetic susceptibility is consistent with the microscopic parameters. The results reveal that a competition between the nearest-neighbor and next-nearest-neighbormore » interactions that together with a relatively large single-ion magnetic anisotropy stabilize the stripe magnetic structure.« less

Crystal structure of a catalytically active, non-toxic endopeptidase derivative of Clostridium botulinum toxin A.

PubMed

Masuyer, Geoffrey; Thiyagarajan, Nethaji; James, Peter L; Marks, Philip M H; Chaddock, John A; Acharya, K Ravi

2009-03-27

Botulinum neurotoxins (BoNTs) modulate cholinergic nerve terminals to result in neurotransmitter blockade. BoNTs consists of catalytic (LC), translocation (Hn) and cell-binding domains (Hc). The binding function of the Hc domain is essential for BoNTs to bind the neuronal cell membrane, therefore, removal of the Hc domain results in a product that retains the endopeptidase activity of the LC but is non-toxic. Thus, a molecule consisting of LC and Hn domains of BoNTs, termed LHn, is a suitable molecule for engineering novel therapeutics. The structure of LHA at 2.6 A reported here provides an understanding of the structural implications and challenges of engineering therapeutic molecules that combine functional properties of LHn of BoNTs with specific ligand partners to target different cell types.

Structural properties of barium stannate

NASA Astrophysics Data System (ADS)

Phelan, D.; Han, F.; Lopez-Bezanilla, A.; Krogstad, M. J.; Gim, Y.; Rong, Y.; Zhang, Junjie; Parshall, D.; Zheng, H.; Cooper, S. L.; Feygenson, M.; Yang, Wenge; Chen, Yu-Sheng

2018-06-01

BaSnO3 has attracted attention as a transparent conducting oxide with high room temperature carrier mobility. We report a series of measurements that were carried out to assess the structure of BaSnO3 over a variety of length scales. Measurements included single crystal neutron and x-ray diffraction, Rietveld and pair distribution analysis of neutron powder diffraction, Raman scattering, and high-pressure x-ray diffraction. Results from the various diffraction probes indicate that both the long-range and local structures are consistent with the cubic symmetry. The diffraction data under pressure was consistent with a robustly cubic phase up to 48.9 GPa, which is supported by density functional calculations. Additionally, transverse phonon velocities were determined from measured dispersion of the transverse acoustic phonon branches, the results of which are in good agreement with previous theoretical estimates and ultrasound measurements.

Effects of electronic and lattice polarization on the band structure of delafossite transparent conductive oxides.

PubMed

Vidal, Julien; Trani, Fabio; Bruneval, Fabien; Marques, Miguel A L; Botti, Silvana

2010-04-02

We use hybrid functionals and restricted self-consistent GW, state-of-the-art theoretical approaches for quasiparticle band structures, to study the electronic states of delafossite Cu(Al,In)O2, the first p-type and bipolar transparent conductive oxides. We show that a self-consistent GW approximation gives remarkably wider band gaps than all the other approaches used so far. Accounting for polaronic effects in the GW scheme we recover a very nice agreement with experiments. Furthermore, the modifications with respect to the Kohn-Sham bands are strongly k dependent, which makes questionable the common practice of using a scissor operator. Finally, our results support the view that the low energy structures found in optical experiments, and initially attributed to an indirect transition, are due to intrinsic defects in the samples.

Local Structure of the Amorphous Precursor to Ba-Hexaferrite Thin Films: An Anisotropic Octahedral Fe-O Glass Network

NASA Astrophysics Data System (ADS)

Snyder, J. E.; Harris, V. G.; Koon, N. C.; Sui, X.; Kryder, M. H.

1996-10-01

Anisotropic local structure has been observed around both the Fe and Ba ions in the amorphous precursor to Ba-hexaferrite thin films, using polarization-dependent extended x-ray-absorption fine structure. This anisotropic local structure, consisting mainly of a network of Fe-O octahedra, determines the orientation of the fast-growing basal planes during crystallization, and thus the directions of the c axes and the resulting magnetic anisotropy.

Single-field consistency relations of large scale structure part III: test of the equivalence principle

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

Creminelli, Paolo; Gleyzes, Jérôme; Vernizzi, Filippo

2014-06-01

The recently derived consistency relations for Large Scale Structure do not hold if the Equivalence Principle (EP) is violated. We show it explicitly in a toy model with two fluids, one of which is coupled to a fifth force. We explore the constraints that galaxy surveys can set on EP violation looking at the squeezed limit of the 3-point function involving two populations of objects. We find that one can explore EP violations of order 10{sup −3}÷10{sup −4} on cosmological scales. Chameleon models are already very constrained by the requirement of screening within the Solar System and only a verymore » tiny region of the parameter space can be explored with this method. We show that no violation of the consistency relations is expected in Galileon models.« less

Transport characteristics of a ZnMgO/ZnO hetero junction and the effect of temperature and Mg content

NASA Astrophysics Data System (ADS)

Uslu, Salih; Yarar, Zeki

2017-02-01

The Ensemble Monte Carlo method is used to calculate the transport characteristics of two dimensional electron gas (2DEG) at a ZnMgO/ZnO hetero structure. The spontaneous and piezoelectric polarizations are considered and there is no intentional doping in either material. Numerical Schrödinger and Poisson equations are solved self consistently to obtain the scattering rates of various scattering mechanisms. The density of carriers, each energy sub bands, potential profile and corresponding wave functions are obtained from the self consistent calculations. The self consistent sub band wave functions of acoustic and optic phonon scattering and interface roughness scattering are used in Monte Carlo method to obtain transport characteristics at ZnMgO/ZnO junction. Two dimensional electron gas confined to ZnMgO/ZnO hetero structure is studied and the effect of temperature and Mg content are investigated.

Back to the Consideration of Future Consequences Scale: time to reconsider?

PubMed

Rappange, David R; Brouwer, Werner B F; van Exel, N Job A

2009-10-01

The Consideration of Future Consequences (CFC) Scale is a measure of the extent to which individuals consider and are influenced by the distant outcomes of current behavior. In this study, the authors conducted factor analysis to investigate the factor structure of the 12-item CFC Scale. The authors found evidence for a multiple factor solution including one completely present-oriented factor consisting of all 7 present-oriented items, and one or two future-oriented factors consisting of the remaining future-oriented items. Further evidence indicated that the present-oriented factor and the 12-item CFC Scale perform similarly in terms of internal consistency and convergent validity. The structure and content of the future-oriented factor(s) is unclear. From the findings, the authors raise questions regarding the construct validity of the CFC Scale, the interpretation of its results, and the usefulness of the CFC scale in its current form in applied research.

Nanoamorphous carbon-based photonic crystal infrared emitters

DOEpatents

Norwood, Robert A [Tucson, AZ; Skotheim, Terje [Tucson, AZ

2011-12-13

Provided is a tunable radiation emitting structure comprising: a nanoamorphous carbon structure having a plurality of relief features provided in a periodic spatial configuration, wherein the relief features are separated from each other by adjacent recessed features, and wherein the nanoamorphous carbon comprises a total of from 0 to 60 atomic percent of one or more dopants of the dopant group consisting of: transition metals, lanthanoids, electro-conductive carbides, silicides and nitrides. In one embodiment, a dopant is selected from the group consisting of: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La and other lanthanides, Hf, Ta, W, Rh, Os, Ir, Pt, Au, and Hg. In one embodiment, a dopant is selected from the group consisting of: electro-conductive carbides (like Mo.sub.2C), silicides (like MoSi.sub.2) and nitrides (like TiN).

Assessing motivation for work environment improvements: internal consistency, reliability and factorial structure.

PubMed

Hedlund, Ann; Ateg, Mattias; Andersson, Ing-Marie; Rosén, Gunnar

2010-04-01

Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation. A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees. The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance. The questionnaire can be a useful tool in improving intervention methods. The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. Copyright 2010 Elsevier Ltd. All rights reserved.

The Multi-Spectral Solar Telescope Array (MSSTA)

NASA Technical Reports Server (NTRS)

Walker, A. B. C., Jr.; Barbee, Troy W., Jr.; Hoover, Richard B.

1997-01-01

In 1987, our consortium pioneered the application of normal incidence multilayer X-ray optics to solar physics by obtaining the first high resolution narrow band, "thermally differentiated" images of the corona', using the emissions of the Fe IX/Fe X complex at ((lambda)lambda) approx. 171 A to 175 A, and He II Lyman (beta) at 256 A. Subsequently, we developed a rocket borne solar observatory, the Multi Spectral Solar Telescope Array (MSSTA) that pioneered multi-thermal imaging of the solar atmosphere, using high resolution narrow band X-ray, EUV and FUV optical systems. Analysis of MSSTA observations has resulted in four significant insights into the structure of the solar atmosphere: (1) the diameter of coronal loops is essentially constant along their length; (2) models of the thermal and density structure of polar plumes based on MSSTA observations have been shown to be consistent with the thesis that they are the source of high speed solar wind streams; (3) the magnetic structure of the footpoints of polar plumes is monopolar, and their thermal structure is consistent with the thesis that the chromosphere at their footpoints is heated by conduction from above; (4) coronal bright points are small loops, typically 3,500 - 20,000 km long (5 sec - 30 sec); their footpoints are located at the poles of bipolar magnetic structures that are are distinguished from other network elements by having a brighter Lyman a signature. Loop models derived for 26 bright points are consistent with the thesis that the chromosphere at their footpoints is heated by conduction from the corona.

Factor analysis of regional brain activation in bipolar and healthy individuals reveals a consistent modular structure.

PubMed

Fleck, David E; Welge, Jeffrey A; Eliassen, James C; Adler, Caleb M; DelBello, Melissa P; Strakowski, Stephen M

2018-07-01

The neurophysiological substrates of cognition and emotion, as seen with fMRI, are generally explained using modular structures. The present study was designed to probe the modular structure of cognitive-emotional processing in bipolar and healthy individuals using factor analysis and compare the results with current conceptions of the neurophysiology of bipolar disorder. Exploratory factor analysis was used to assess patterns of covariation among brain regions-of-interest activated during the Continuous Performance Task with Emotional and Neutral Distractors in healthy and bipolar individuals without a priori constraints on the number or composition of latent factors. Results indicated a common cognitive-emotional network consisting of prefrontal, medial temporal, limbic, parietal, anterior cingulate and posterior cingulate modules. However, reduced brain activation to emotional stimuli in the frontal, medial temporal and limbic modules was apparent in the bipolar relative to the healthy group, potentially accounting for emotional dysregulation in bipolar disorder. This study is limited by a relatively small sample size recruited at a single site. The results have yet to be validated on a larger independent sample. Although the modular structure of cognitive-emotional processing is similar in bipolar and healthy individuals, activation in response to emotional/neutral cues varies. These findings are not only consistent with recent conceptions of mood regulation in bipolar disorder, but also suggest that regional activation can be considered within tighter modular structures without compromising data interpretation. This demonstration may serve as a template for data reduction in future region-of-interest analyses to increase statistical power. Copyright © 2018 Elsevier B.V. All rights reserved.

Structure-Preserving Smoothing of Biomedical Images

NASA Astrophysics Data System (ADS)

Gil, Debora; Hernàndez-Sabaté, Aura; Burnat, Mireia; Jansen, Steven; Martínez-Villalta, Jordi

Smoothing of biomedical images should preserve gray-level transitions between adjacent tissues, while restoring contours consistent with anatomical structures. Anisotropic diffusion operators are based on image appearance discontinuities (either local or contextual) and might fail at weak inter-tissue transitions. Meanwhile, the output of block-wise and morphological operations is prone to present a block structure due to the shape and size of the considered pixel neighborhood.

Assessing Defense Structure in School-Age Children Using the Response Evaluation Measure-71-Youth Version (REM-Y-71)

ERIC Educational Resources Information Center

Araujo, Katy B.; Medic, Sanja; Yasnovsky, Jessica; Steiner, Hans

2006-01-01

This study used the Response Evaluation Measure-Youth (REM-Y-71), a self-report measure of 21 defense reactions, among school-age children. Participants were elementary and middle school students (n=290; grades 3-8; age range: 8-15; mean=11.73). Factor analysis revealed a 2-factor defense structure consistent with structure among high school and…

Effect of Se concentration on photonic bandgap of 1-D As-S-Se/air multilayers

NASA Astrophysics Data System (ADS)

Singh, Rajpal; Suthar, B.; Bhargava, A.

2018-05-01

The photonic band structure of 1-D chalcogenide photonic crystal consisting of As-S-Se/air multilayered structure is studied. The photonic band structure is calculated using plane wave expansion method. The effect of Se constration on the photonic bandgap is studied. It is found that the photonic bandgap increases with Se-concentration and shows the red shift.

Self-Regulation in the Midst of Complexity: A Case Study of High School Physics Students Engaged in Ill-Structured Problem Solving

ERIC Educational Resources Information Center

Milbourne, Jeffrey David

2016-01-01

The purpose of this dissertation study was to explore the experiences of high school physics students who were solving complex, ill-structured problems, in an effort to better understand how self-regulatory behavior mediated the project experience. Consistent with Voss, Green, Post, and Penner's (1983) conception of an ill-structured problem in…

Applying Massively Parallel Kinetic Monte Carlo Methods to Simulate Grain Growth and Sintering in Powdered Metals

DTIC Science & Technology

2011-09-01

Structure Evolution During Sintering From [19]. ...................................20 Figure 10. Ising Model Configuration With Eight Nearest Neighbors...INTRODUCTION A. MOTIVATION The ability to fabricate structural components from metals with a fine (micron- sized), controlled grain size is one of the...hallmarks of modern, structural metallurgy. Powder metallurgy, in particular, consists of powder manufacture, powder blending, compacting, and sintering

78 FR 66910 - Notice of Competing Preliminary Permit Applications Accepted for Filing and Soliciting Comments...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-07

...-foot-tall water intake structure; (2) a 155-foot-wide, 189-foot-long concrete powerhouse containing two turbine-generators each rated at 25 megawatts (MW) for a total installed capacity of 50 MW; (3) a 160-foot... Island dam structure and consist of: (1) A 225-foot-wide, 50-foot-long water intake structure; (2) a 160...

Structured Forms Reference Set of Binary Images II (SFRS2)

National Institute of Standards and Technology Data Gateway

NIST Structured Forms Reference Set of Binary Images II (SFRS2) (Web, free access)   The second NIST database of structured forms (Special Database 6) consists of 5,595 pages of binary, black-and-white images of synthesized documents containing hand-print. The documents in this database are 12 different tax forms with the IRS 1040 Package X for the year 1988.

Structure of Biocompatible Coatings Produced from Hydroxyapatite Nanoparticles by Detonation Spraying

NASA Astrophysics Data System (ADS)

Nosenko, Valentyna; Strutynska, Nataliia; Vorona, Igor; Zatovsky, Igor; Dzhagan, Volodymyr; Lemishko, Sergiy; Epple, Matthias; Prymak, Oleg; Baran, Nikolai; Ishchenko, Stanislav; Slobodyanik, Nikolai; Prylutskyy, Yuriy; Klyui, Nickolai; Temchenko, Volodymyr

2015-12-01

Detonation-produced hydroxyapatite coatings were studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The source material for detonation spraying was a B-type carbonated hydroxyapatite powder. The coatings consisted of tetracalcium phosphate and apatite. The ratio depended slightly on the degree of crystallinity of the initial powder and processing parameters of the coating preparation. The tetracalcium phosphate phase was homogeneous; the apatite phase contained defects localized on the sixfold axis and consisted of hydroxyapatite and oxyapatite. Technological factors contributing to the transformation of hydroxyapatite powder structure during coating formation by detonation spraying are discussed.

Structural polarity in the Chara rhizoid: a reevaluation

NASA Technical Reports Server (NTRS)

Kiss, J. Z.; Staehelin, L. A.

1993-01-01

The Chara rhizoid is a useful model system to study gravitropism since all phases of gravitropism occur in a single cell. Despite years of study, a complete description of the distinctive ultrastructure of Chara rhizoids is not available. Therefore, in this paper, we reevaluate the ultrastructural features of vertically grown rhizoids, which have a structural polarity consisting of seven distinct zones. We also characterize the apical vesicles and the cell wall in these rhizoids by using antibodies against pectic polysaccharides. These studies demonstrate that the cell wall consists of two pectinaceous domains and that a distinct population of apical vesicles contain methyl esterified pectin.

Persistent superconductor currents in holographic lattices.

PubMed

Iizuka, Norihiro; Ishibashi, Akihiro; Maeda, Kengo

2014-07-04

We consider a persistent superconductor current along the direction with no translational symmetry in a holographic gravity model. Incorporating a lattice structure into the model, we numerically construct novel solutions of hairy charged stationary black branes with momentum or rotation along the latticed direction. The lattice structure prevents the horizon from rotating, and the total momentum is only carried by matter fields outside the black brane horizon. This is consistent with the black hole rigidity theorem, and it suggests that in dual field theory with lattices, superconductor currents are made up of "composite" fields, rather than "fractionalized" degrees of freedom. We also show that our solutions are consistent with the superfluid hydrodynamics.

Electronic Structure of Tl2Ba2CuO(6+Delta) Epitaxial Films Measured by X-Ray Photoemission

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Ren, Z. F.; Wang, J. H.

1996-01-01

The valence electronic structure and core levels of Tl2Ba2CuO(6 + delta) (Tl-2201) epitaxial films have been measured with X-ray photoelectron spectroscopy and are compared to those of Tl2Ba2CaCu2O(8 + delta) (Tl-2212). Changes in the Tl-2201 core-level binding energies with oxygen doping are consistent with a change in the chemical potential. Differences between the Tl-2201 and Tl-2212 measured densities of states are consistent with the calculated Cu 3d and Tl 6s partial densities of states.

Structure of bacterial lipopolysaccharides.

PubMed

Caroff, Martine; Karibian, Doris

2003-11-14

Bacterial lipopolysaccharides are the major components of the outer surface of Gram-negative bacteria They are often of interest in medicine for their immunomodulatory properties. In small amounts they can be beneficial, but in larger amounts they may cause endotoxic shock. Although they share a common architecture, their structural details exert a strong influence on their activity. These molecules comprise: a lipid moiety, called lipid A, which is considered to be the endotoxic component, a glycosidic part consisting of a core of approximately 10 monosaccharides and, in "smooth-type" lipopolysaccharides, a third region, named O-chain, consisting of repetitive subunits of one to eight monosaccharides responsible for much of the immunospecificity of the bacterial cell.

Structure of Biocompatible Coatings Produced from Hydroxyapatite Nanoparticles by Detonation Spraying.

PubMed

Nosenko, Valentyna; Strutynska, Nataliia; Vorona, Igor; Zatovsky, Igor; Dzhagan, Volodymyr; Lemishko, Sergiy; Epple, Matthias; Prymak, Oleg; Baran, Nikolai; Ishchenko, Stanislav; Slobodyanik, Nikolai; Prylutskyy, Yuriy; Klyui, Nickolai; Temchenko, Volodymyr

2015-12-01

Detonation-produced hydroxyapatite coatings were studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The source material for detonation spraying was a B-type carbonated hydroxyapatite powder. The coatings consisted of tetracalcium phosphate and apatite. The ratio depended slightly on the degree of crystallinity of the initial powder and processing parameters of the coating preparation. The tetracalcium phosphate phase was homogeneous; the apatite phase contained defects localized on the sixfold axis and consisted of hydroxyapatite and oxyapatite. Technological factors contributing to the transformation of hydroxyapatite powder structure during coating formation by detonation spraying are discussed.

Consistent linearization of the element-independent corotational formulation for the structural analysis of general shells

NASA Technical Reports Server (NTRS)

Rankin, C. C.

1988-01-01

A consistent linearization is provided for the element-dependent corotational formulation, providing the proper first and second variation of the strain energy. As a result, the warping problem that has plagued flat elements has been overcome, with beneficial effects carried over to linear solutions. True Newton quadratic convergence has been restored to the Structural Analysis of General Shells (STAGS) code for conservative loading using the full corotational implementation. Some implications for general finite element analysis are discussed, including what effect the automatic frame invariance provided by this work might have on the development of new, improved elements.

Properties of small Ar sub N-1 K/+/ ionic clusters

NASA Technical Reports Server (NTRS)

Etters, R. D.; Danilowicz, R.; Dugan, J.

1977-01-01

A self-consistent formalism is developed that, based upon a many-body potential, dynamically determines the thermodynamic properties of ionic clusters without an a priori designation of the equilibrium structures. Aggregates consisting of a single closed shell K(+) ion and N-1 isoelectronic argon atoms were studied. The clusters form crystallites at low temperatures, and melting transitions and spontaneous dissociations are indicated. The results confirm experimental evidence that shows that ionic clusters become less stable with increasing N. The crystallite structures formed by four different clusters are isosceles triangle, skewed form, octahedron with ion in the middle, and icosahedron with the ion in the middle.

Neural Schematics as a unified formal graphical representation of large-scale Neural Network Structures.

PubMed

Ehrlich, Matthias; Schüffny, René

2013-01-01

One of the major outcomes of neuroscientific research are models of Neural Network Structures (NNSs). Descriptions of these models usually consist of a non-standardized mixture of text, figures, and other means of visual information communication in print media. However, as neuroscience is an interdisciplinary domain by nature, a standardized way of consistently representing models of NNSs is required. While generic descriptions of such models in textual form have recently been developed, a formalized way of schematically expressing them does not exist to date. Hence, in this paper we present Neural Schematics as a concept inspired by similar approaches from other disciplines for a generic two dimensional representation of said structures. After introducing NNSs in general, a set of current visualizations of models of NNSs is reviewed and analyzed for what information they convey and how their elements are rendered. This analysis then allows for the definition of general items and symbols to consistently represent these models as Neural Schematics on a two dimensional plane. We will illustrate the possibilities an agreed upon standard can yield on sampled diagrams transformed into Neural Schematics and an example application for the design and modeling of large-scale NNSs.

Structural characterization of anti-complementary polysaccharides from the leaves of Artemisia princeps.

PubMed

Yamada, H; Otsuka, Y; Omura, S

1986-08-01

Structural characterizations of the anti-complementary acidic heteroglycans, AAF IIb-2 and IIb-3, obtained from the leaves of Artemisia princeps pamp have been studied. AAF IIb-2 consists of rhamnose, xylose, arabinose, galactose, glucose and uronic acids (glucuronic acid and galacturonic acid) in the molar ratio of 7.6:7.6:13.0:10.9:3.0:57.9, and AAF IIb-3 consists of the same sugars in the ratio of 3.9:2.6:24.7:19.7:2.6:46.5. Methylation analysis including carboxyl-reduction and also selective enzymolysis using EXO-alpha- L-arabinofuranosidase suggested that AAF IIb-3 has a main chain consisting of (1-->4)-linked galacturonic acid and (1-->2)-linked rhamnose mostly substituted at the O-4 position. AAF IIb-3 also contained arabino-3,6-galactan moiety and most of the arabinose was present as an alpha- L-furanosyl residue in the non-reducing terminals and highly branched side chains which mostly attached to the O-3 position of (1-->6)-linked galactopyranosyl residue. The basic structure of AAF IIb-2 is similar to that of AAF IIb-3, but IIb-3 has a higher arabinogalactan content than IIb-2.

Gravitational evidence for an undifferentiated Callisto.

PubMed

Anderson, J D; Lau, E L; Sjogren, W L; Schubert, G; Moore, W B

1997-05-15

Before the arrival of the Galileo spacecraft at Jupiter, models for the interior structure of the four galilean satellites--Io, Europa, Ganymede and Callisto-ranged from uniform mixtures of rock and ice (that is, undifferentiated objects) or rocky cores surrounded by a mantle of water ice. Now it appears that Io has a large metallic core and that Ganymede is strongly differentiated, most probably into a three-layer structure consisting of a metallic core, a silicate mantle and a deep outer layer of ice. Direct information on the interior structure of Callisto determined from previous spacecraft fly-bys was essentially limited to an estimate of the mean density being intermediate between pure ice and pure rock. Here we report measurements of Callisto's gravitational field which reveal that, in contrast to Io and Ganymede, this galilean satellite is most probably a homogeneous object consisting of a solar mixture of 40% compressed ice and 60% rock (including iron and iron sulphide). Callisto's undifferentiated state is consistent with the apparent lack of an intrinsic magnetic field, and indicates that the outermost galilean satellite has not experienced a heating phase sufficiently high to separate its rock and metal components from the lighter ices.

Validation of a coupled core-transport, pedestal-structure, current-profile and equilibrium model

NASA Astrophysics Data System (ADS)

Meneghini, O.

2015-11-01

The first workflow capable of predicting the self-consistent solution to the coupled core-transport, pedestal structure, and equilibrium problems from first-principles and its experimental tests are presented. Validation with DIII-D discharges in high confinement regimes shows that the workflow is capable of robustly predicting the kinetic profiles from on axis to the separatrix and matching the experimental measurements to within their uncertainty, with no prior knowledge of the pedestal height nor of any measurement of the temperature or pressure. Self-consistent coupling has proven to be essential to match the experimental results, and capture the non-linear physics that governs the core and pedestal solutions. In particular, clear stabilization of the pedestal peeling ballooning instabilities by the global Shafranov shift and destabilization by additional edge bootstrap current, and subsequent effect on the core plasma profiles, have been clearly observed and documented. In our model, self-consistency is achieved by iterating between the TGYRO core transport solver (with NEO and TGLF for neoclassical and turbulent flux), and the pedestal structure predicted by the EPED model. A self-consistent equilibrium is calculated by EFIT, while the ONETWO transport package evolves the current profile and calculates the particle and energy sources. The capabilities of such workflow are shown to be critical for the design of future experiments such as ITER and FNSF, which operate in a regime where the equilibrium, the pedestal, and the core transport problems are strongly coupled, and for which none of these quantities can be assumed to be known. Self-consistent core-pedestal predictions for ITER, as well as initial optimizations, will be presented. Supported by the US Department of Energy under DE-FC02-04ER54698, DE-SC0012652.

Consistent Individual Differences Drive Collective Behavior and Group Functioning of Schooling Fish.

PubMed

Jolles, Jolle W; Boogert, Neeltje J; Sridhar, Vivek H; Couzin, Iain D; Manica, Andrea

2017-09-25

The ubiquity of consistent inter-individual differences in behavior ("animal personalities") [1, 2] suggests that they might play a fundamental role in driving the movements and functioning of animal groups [3, 4], including their collective decision-making, foraging performance, and predator avoidance. Despite increasing evidence that highlights their importance [5-16], we still lack a unified mechanistic framework to explain and to predict how consistent inter-individual differences may drive collective behavior. Here we investigate how the structure, leadership, movement dynamics, and foraging performance of groups can emerge from inter-individual differences by high-resolution tracking of known behavioral types in free-swimming stickleback (Gasterosteus aculeatus) shoals. We show that individual's propensity to stay near others, measured by a classic "sociability" assay, was negatively linked to swim speed across a range of contexts, and predicted spatial positioning and leadership within groups as well as differences in structure and movement dynamics between groups. In turn, this trait, together with individual's exploratory tendency, measured by a classic "boldness" assay, explained individual and group foraging performance. These effects of consistent individual differences on group-level states emerged naturally from a generic model of self-organizing groups composed of individuals differing in speed and goal-orientedness. Our study provides experimental and theoretical evidence for a simple mechanism to explain the emergence of collective behavior from consistent individual differences, including variation in the structure, leadership, movement dynamics, and functional capabilities of groups, across social and ecological scales. In addition, we demonstrate individual performance is conditional on group composition, indicating how social selection may drive behavioral differentiation between individuals. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Discovery of novel mosquito repellents from structure-activity studies

USDA-ARS?s Scientific Manuscript database

For the AGRO division: Recent Developments in Invertebrate Repellents. The USDA historical archives of repellents and toxicants consists of over 30,000 chemical structures tested over the past 60 years. We have undertaken a collaborative research project to initially target six subsets of these com...

Household Structure, Coupling Constraints, and the Nonpartner Victimization Risks of Adults

ERIC Educational Resources Information Center

Yule, Carolyn; Griffiths, Elizabeth

2009-01-01

Victimization studies consistently find that household structure influences the risk of personal and property victimization among adult household members, with those in "traditional" homes enjoying the most protection from victimization and lone parents experiencing the greatest vulnerability. Drawing on the concept of "coupling…

The executive personal finance scale: item analyses.

PubMed

Lester, David; Spinella, Marcello

2007-12-01

A scale devised to measure executive personal money management was examined for its factorial structure using 138 college students. On the whole, the factor analysis confirmed the subscale structure of the scale, but the Planning subscale appeared to consist of two distinct components, investment behavior and saving behavior.

Foam rigidized inflatable structural assemblies

NASA Technical Reports Server (NTRS)

Tinker, Michael L. (Inventor); Schnell, Andrew R. (Inventor)

2010-01-01

An inflatable and rigidizable structure for use as a habitat or a load bearing structure is disclosed. The structure consists of an outer wall and an inner wall defining a containment member and a bladder. The bladder is pressurized to erect the structure from an initially collapsed state. The containment member is subsequently injected with rigidizable fluid through an arrangement of injection ports. Exhaust gases from the curing rigidizable fluid are vented through an arrangement of exhaust ports. The rate of erection can be controlled by frictional engagement with a container or by using a tether. A method for fabricating a tubular structure is disclosed.

Structural design and analysis for an ultra low CTE optical bench for the Hubble Space Telescope corrective optics

NASA Technical Reports Server (NTRS)

Neam, Douglas C.; Gerber, John D.

1992-01-01

The stringent stability requirements of the Corrective Optics Space Telescope Axial Replacement (COSTAR) necessitates a Deployable Optical Bench (DOB) with both a low CTE and high resonant frequency. The DOB design consists of a monocoque thin shell structure which marries metallic machined parts with graphite epoxy formed structure. Structural analysis of the DOB has been integrated into the laminate design and optimization process. Also, the structural analytical results are compared with vibration and thermal test data to assess the reliability of the analysis.

Validation of the Personal Need for Structure Scale in Chinese.

PubMed

Shi, Junqi; Wang, Lei; Chen, Yang

2009-08-01

To validate the Chinese version of the Personal Need for Structure Scale, questionnaires were administered to 1,418 individuals in three samples. Item-total correlations and internal consistency of the scale were acceptable. The test-retest reliability was .79. Confirmatory factor analysis indicated that the Chinese version comprised two dimensions, as did the original version; Desire for Structure and Response to Lack of Structure. Correlation coefficients between the Personal Need for Structure Scale and other related measures indicated that the scale has acceptable discriminant validity and convergent validity.

Quick-Connect/Disconnect Joint For Truss Structures

NASA Technical Reports Server (NTRS)

Sprague, Benny B.

1991-01-01

Simple connector used for temporary structures and pipes. Truss connector joins and aligns structural members. Consists of two sections, one flanged and other with mating internal groove. When flanged half inserted in groove, moves lever of trigger mechanism upward. Cone then shoots into grooved half. Attached without tools in less than 2 seconds and taken apart just as quickly and easily. Developed for assembling structures in outer space, also useful for temporary terrestrial structures like scaffolds and portable bleachers. With modifications, used to join sections of pipelines carrying liquids or gases.

Structure and Composition of the Bacillus anthracis Capsule

PubMed Central

Avakyan, A. A.; Katz, L. N.; Levina, K. N.; Pavlova, I. B.

1965-01-01

Avakyan, A. A. (Academy of Medical Sciences, Moscow, USSR), L. N. Katz, K. N. Levina, and I. B. Pavlova. Structure and composition of the Bacillus anthracis capsule. J. Bacteriol. 90:1082–1095. 1965.—Observations by various methods of light microscopy (phase contrast, dark-field, and fluorescence) revealed the complex structure of the Bacillus anthracis capsule, which changes regularly during the growth cycle of the culture. Special cytological methods of staining the capsule made it possible to study its fine structure, which is not revealed by negative staining with India ink. For example, the capsule shows a membranelike outline, fine transverse lines, and interruptions and transverse septa traversing the entire capsule. By using cytochemical methods, it was found that the capsule has a stratified structure and that the various layers of the capsule differ as to the value of the isoelectric point, metachromatic ability, sensitivity to various enzymes, and, consequently, chemical composition. It was thus shown that the membranelike outline of the capsule consists of peptides and neutral mucopolysaccharides. The middle part of the capsule consists of a complex of substances of both polysaccharide and protein nature, and the inner part consists of acid mucopolysaccharides. Observation of the capsular forms of B. anthracis by means of an electron microscope revealed differences in the osmiophilia and submicroscopic structure of the membranelike outline and the middle and inner parts of the capsule. Immunochemical studies conducted by the fluorescent-antibody method revealed localization of antigens in different parts of the capsule, and made it possible to differentiate the capsular antigens according to their serum-staining ability and according of their relations to enzymes, i.e., their chemical composition. This paper concerns the possibility of studying the fine structure of bacterial capsules in fixed preparations, and the differences and similarities of the antigens of the capsule and cell wall of B. anthracis and of the related species, B. megaterium. Images PMID:4954516

Deep Crustal Structure beneath Large Igneous Provinces and the Petrologic Evolution of Flood Basalts

NASA Astrophysics Data System (ADS)

Richards, Mark; Ridley, Victoria

2010-05-01

We present a review of seismological constraints on deep crustal structures underlying large igneous provinces (LIPs), largely from wide-angle seismic refraction surveys. The main purpose of this review is to ascertain whether this seismic evidence is consistent with, or contrary to, petrological models for the genesis of flood basalt lavas. Where high-quality data are available beneath continental flood basalt (CFB) provinces (Emeishan, Columbia River, Deccan, Siberia), high-velocity structures (Vp ~6.9-7.5 km/sec) are typically found immediately overlying the Moho in layers of order ~5-15 km thick. Oceanic plateau (OP) LIPs exhibit similar layers, with a conspicuous layer of very high crustal velocity (Vp~7.7 km/sec) beneath the enormous Ontong-Java plateau. These structures are similar to inferred ultramafic underplating structures seen beneath active hotspots such as Hawaii, the Marqueses, and La Reunion. Petrogenetic models for flood basalt volcanism based on hot plume melting beneath mature lithosphere suggest that these deep seismic structures may consist in large part of cumulate bodies of olivine and clinopyroxene which result from ponding and deep-crustal fractionation of ultramafic primary melts. Such fractionation is necessary to produce basalts with typical MgO contents of ~6-8%, as observed for the vast bulk of observed flood basalts, from primary melts with MgO contents of order ~15-18% (or greater) such as result from hot, deep melting beneath the lithosphere. The volumes of cumulate bodies and ultramafic intrusions in the lowermost crust, often described in the literature as "underplating," are comparable to those of the overlying basaltic formations, also consistent with petrological models. Further definition of the deep seismic structure beneath such prominent LIPs as the Ontong-Java Plateau could place better constraints on flood basalt petrogenesis by determining the relative volumes of ultramafic bodies and basaltic lavas, thereby better constraining the overall process of LIP emplacement.