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Sample records for adaptive behavior composite

  1. Static aeroelastic behavior of an adaptive laminated piezoelectric composite wing

    NASA Technical Reports Server (NTRS)

    Weisshaar, T. A.; Ehlers, S. M.

    1990-01-01

    The effect of using an adaptive material to modify the static aeroelastic behavior of a uniform wing is examined. The wing structure is idealized as a laminated sandwich structure with piezoelectric layers in the upper and lower skins. A feedback system that senses the wing root loads applies a constant electric field to the piezoelectric actuator. Modification of pure torsional deformaton behavior and pure bending deformation are investigated, as is the case of an anisotropic composite swept wing. The use of piezoelectric actuators to create an adaptive structure is found to alter static aeroelastic behavior in that the proper choice of the feedback gain can increase or decrease the aeroelastic divergence speed. This concept also may be used to actively change the lift effectiveness of a wing. The ability to modify static aeroelastic behavior is limited by physical limitations of the piezoelectric material and the manner in which it is integrated into the parent structure.

  2. Vibrational behavior of adaptive aircraft wing structures modelled as composite thin-walled beams

    NASA Technical Reports Server (NTRS)

    Song, O.; Librescu, L.; Rogers, C. A.

    1992-01-01

    The vibrational behavior of cantilevered aircraft wings modeled as thin-walled beams and incorporating piezoelectric effects is studied. Based on the converse piezoelectric effect, the system of piezoelectric actuators conveniently located on the wing yield the control of its associated vertical and lateral bending eigenfrequencies. The possibility revealed by this study enabling one to increase adaptively the eigenfrequencies of thin-walled cantilevered beams could play a significant role in the control of the dynamic response and flutter of wing and rotor blade structures.

  3. Probabilistic assessment of uncertain adaptive hybrid composites

    NASA Technical Reports Server (NTRS)

    Shiao, Michael C.; Singhal, Surendra N.; Chamis, Christos C.

    1994-01-01

    Adaptive composite structures using actuation materials, such as piezoelectric fibers, were assessed probabilistically utilizing intraply hybrid composite mechanics in conjunction with probabilistic composite structural analysis. Uncertainties associated with the actuation material as well as the uncertainties in the regular (traditional) composite material properties were quantified and considered in the assessment. Static and buckling analyses were performed for rectangular panels with various boundary conditions and different control arrangements. The probability density functions of the structural behavior, such as maximum displacement and critical buckling load, were computationally simulated. The results of the assessment indicate that improved design and reliability can be achieved with actuation material.

  4. Adaptive Behavior: A Conceptual Analysis.

    ERIC Educational Resources Information Center

    Schmidt, Mary W.; Salvia, John

    1984-01-01

    The paper presents a model that examines the domain of adaptive behavior in terms of components (including physical needs, care of the environment, vocation, and understanding social conventions), and levels of performance (such as timing and degree of adaptation). (Author/CL)

  5. The Adaptive Behavior Rating Scale.

    ERIC Educational Resources Information Center

    Meyer, William J.

    A scale to identify important behaviors in preschool children was developed, and ratings were related to more traditional indices of development and academic readiness. Teacher interviews were used to identify 62 specific behaviors related to maximally adapted and maximally maladapted kindergarten children. These were incorporated into a…

  6. Behavior of adaptive digital erosions

    NASA Astrophysics Data System (ADS)

    Cuciurean-Zapan, Clara; Dougherty, Edward R.; Chen, Yidong

    1996-10-01

    Design of statistically optimal erosion-based filters is problematic due to the complexity of the search process. Specialized search techniques and constraints on optimality are used to mitigate the full search. Adaptation of structuring elements has also ben employed. The present paper looks at the behavior of an adaptive filter relative to the actual optimal filter for a single erosion in two models, signal-union-noise and dilation. It does so in the context of state transitions, where filter states are stacks that determine the structuring element upon thresholding.

  7. Adaptive capture of expert behavior

    SciTech Connect

    Jones, R.D.; Barrett, C.L.; Hand, U.; Gordon, R.C.

    1994-08-01

    The authors smoothed and captured a set of expert rules with adaptive networks. The motivation for doing this is discussed. (1) Smoothing leads to stabler control actions. (2) For some sets of rules, the evaluation of the rules can be sped up. This is important in large-scale simulations where many intelligent elements are present. (3) Variability of the intelligent elements can be achieved by adjusting the weights in an adaptive network. (4) After capture has occurred, the weights can be adjusted based on performance criteria. The authors thus have the capability of learning a new set of rules that lead to better performance. The set of rules the authors chose to capture were based on a set of threat determining rules for tank commanders. The approach in this paper: (1) They smoothed the rules. The rule set was converted into a simple set of arithmetic statements. Continuous, non-binary inputs, are now permitted. (2) An operational measure of capturability was developed. (3) They chose four candidate networks for the rule set capture: (a) multi-linear network, (b) adaptive partial least squares, (c) connectionist normalized local spline (CNLS) network, and (d) CNLS net with a PLS preprocessor. These networks were able to capture the rule set to within a few percent. For the simple tank rule set, the multi-linear network performed the best. When the rules were modified to include more nonlinear behavior, CNLS net performed better than the other three nets which made linear assumptions. (4) The networks were tested for robustness to input noise. Noise levels of plus or minus 10% had no real effect on the network performance. Noise levels in the plus or minus 30% range degraded performance by a factor of two. Some performance enhancement occurred when the networks were trained with noisy data. (5) The scaling of the evaluation time was calculated. (6) Human variation can be mimicked in all the networks by perturbing the weights.

  8. From Concept to Measurement in Adaptive Behavior.

    ERIC Educational Resources Information Center

    Leland, Henry

    The concept of adaptation is approached from several directions: (1) a discussion of the meanings of adaptation; (2) a functional socio-cultural set of considerations on which one can base measurement in adaptive behavior; and (3) a practical, applied conceptualization relative to the utilization of the obtained information and the reasons for…

  9. Adaptive Behavior Profiles of Students with Disabilities

    ERIC Educational Resources Information Center

    Ditterline, Jeffrey; Banner, Diane; Oakland, Thomas; Becton, Daniel

    2008-01-01

    Assessment of adaptive behavior traditionally has been associated with the identification of individuals with mental retardation. Information on adaptive behavior increasingly is being used for comprehensive assessment, treatment planning, intervention, and program evaluation for individuals with various disorders. Data from the normative samples…

  10. Using Behavioral Questionnaires to Identify Adaptive Deficits in Elementary School Children.

    ERIC Educational Resources Information Center

    Pearson, Deborah A.; Lachar, David

    1994-01-01

    Obtained responses to Child Behavior Checklist (CBCL) and revised Personality Inventory for Children (PIC-R) for 88 elementary-age boys. Used CBCL and PIC-R scales to predict three domain scales and Adaptive Behavior Composite from Vineland Adaptive Behavior Scales. Results suggest that behavioral questionnaires can be used to efficiently identify…

  11. Adaptive Controller Effects on Pilot Behavior

    NASA Technical Reports Server (NTRS)

    Trujillo, Anna C.; Gregory, Irene M.; Hempley, Lucas E.

    2014-01-01

    Adaptive control provides robustness and resilience for highly uncertain, and potentially unpredictable, flight dynamics characteristic. Some of the recent flight experiences of pilot-in-the-loop with an adaptive controller have exhibited unpredicted interactions. In retrospect, this is not surprising once it is realized that there are now two adaptive controllers interacting, the software adaptive control system and the pilot. An experiment was conducted to categorize these interactions on the pilot with an adaptive controller during control surface failures. One of the objectives of this experiment was to determine how the adaptation time of the controller affects pilots. The pitch and roll errors, and stick input increased for increasing adaptation time and during the segment when the adaptive controller was adapting. Not surprisingly, altitude, cross track and angle deviations, and vertical velocity also increase during the failure and then slowly return to pre-failure levels. Subjects may change their behavior even as an adaptive controller is adapting with additional stick inputs. Therefore, the adaptive controller should adapt as fast as possible to minimize flight track errors. This will minimize undesirable interactions between the pilot and the adaptive controller and maintain maneuvering precision.

  12. Complex adaptive behavior and dexterous action

    PubMed Central

    Harrison, Steven J.; Stergiou, Nicholas

    2016-01-01

    Dexterous action, as conceptualized by Bernstein in his influential ecological analysis of human behavior, is revealed in the ability to flexibly generate behaviors that are adaptively tailored to the demands of the context in which they are embedded. Conceived as complex adaptive behavior, dexterity depends upon the qualities of robustness and degeneracy, and is supported by the functional complexity of the agent-environment system. Using Bernstein’s and Gibson’s ecological analyses of behavior situated in natural environments as conceptual touchstones, we consider the hypothesis that complex adaptive behavior capitalizes upon general principles of self-organization. Here, we outline a perspective in which the complex interactivity of nervous-system, body, and environment is revealed as an essential resource for adaptive behavior. From this perspective, we consider the implications for interpreting the functionality and dysfunctionality of human behavior. This paper demonstrates that, optimal variability, the topic of this special issue, is a logical consequence of interpreting the functionality of human behavior as complex adaptive behavior. PMID:26375932

  13. Structural behavior of SMA composite beams

    SciTech Connect

    Hebda, D.A.; White, S.R.

    1995-12-31

    Shape memory alloy (SMA) composites are one class of adaptive materials in which SMA wires are embedded in a polymer matrix composite material. By selectively activating the SMA, wires, the beam shape can be controlled or {open_quotes}adapted{close_quotes} to different loading conditions. For instance, an adaptive beam could be used as a torque box for an aircraft wing where coupled bending-twisting behavior may be desirable. SMA composite beams were manufactured using a procedure developed previously and mechanically tested under static loading conditions. Nitinol (SMA) wires composed of 55% nickel and 45% titanium were trained for two-way shape memory (TWSM) and tested to determine the transformation temperatures. Once trained, the wires undergo a reversible phase transformation from martensite to austenite as the temperature is increased. This transformation leads to shape recovery and associated recovery strains. These recovery strains are used to apply forces which deflect the SMA beams during static actuation. Their structural behavior is correlated using simple beam theory. Thermal effects during processing are shown to have a major influence on structural behavior.

  14. Adaptive Behavior for Mobile Robots

    NASA Technical Reports Server (NTRS)

    Huntsberger, Terrance

    2009-01-01

    The term "System for Mobility and Access to Rough Terrain" (SMART) denotes a theoretical framework, a control architecture, and an algorithm that implements the framework and architecture, for enabling a land-mobile robot to adapt to changing conditions. SMART is intended to enable the robot to recognize adverse terrain conditions beyond its optimal operational envelope, and, in response, to intelligently reconfigure itself (e.g., adjust suspension heights or baseline distances between suspension points) or adapt its driving techniques (e.g., engage in a crabbing motion as a switchback technique for ascending steep terrain). Conceived for original application aboard Mars rovers and similar autonomous or semi-autonomous mobile robots used in exploration of remote planets, SMART could also be applied to autonomous terrestrial vehicles to be used for search, rescue, and/or exploration on rough terrain.

  15. Neurophysiology of performance monitoring and adaptive behavior.

    PubMed

    Ullsperger, Markus; Danielmeier, Claudia; Jocham, Gerhard

    2014-01-01

    Successful goal-directed behavior requires not only correct action selection, planning, and execution but also the ability to flexibly adapt behavior when performance problems occur or the environment changes. A prerequisite for determining the necessity, type, and magnitude of adjustments is to continuously monitor the course and outcome of one's actions. Feedback-control loops correcting deviations from intended states constitute a basic functional principle of adaptation at all levels of the nervous system. Here, we review the neurophysiology of evaluating action course and outcome with respect to their valence, i.e., reward and punishment, and initiating short- and long-term adaptations, learning, and decisions. Based on studies in humans and other mammals, we outline the physiological principles of performance monitoring and subsequent cognitive, motivational, autonomic, and behavioral adaptation and link them to the underlying neuroanatomy, neurochemistry, psychological theories, and computational models. We provide an overview of invasive and noninvasive systemic measures, such as electrophysiological, neuroimaging, and lesion data. We describe how a wide network of brain areas encompassing frontal cortices, basal ganglia, thalamus, and monoaminergic brain stem nuclei detects and evaluates deviations of actual from predicted states indicating changed action costs or outcomes. This information is used to learn and update stimulus and action values, guide action selection, and recruit adaptive mechanisms that compensate errors and optimize goal achievement. PMID:24382883

  16. Adaptive human behavior in epidemiological models.

    PubMed

    Fenichel, Eli P; Castillo-Chavez, Carlos; Ceddia, M G; Chowell, Gerardo; Parra, Paula A Gonzalez; Hickling, Graham J; Holloway, Garth; Horan, Richard; Morin, Benjamin; Perrings, Charles; Springborn, Michael; Velazquez, Leticia; Villalobos, Cristina

    2011-04-12

    The science and management of infectious disease are entering a new stage. Increasingly public policy to manage epidemics focuses on motivating people, through social distancing policies, to alter their behavior to reduce contacts and reduce public disease risk. Person-to-person contacts drive human disease dynamics. People value such contacts and are willing to accept some disease risk to gain contact-related benefits. The cost-benefit trade-offs that shape contact behavior, and hence the course of epidemics, are often only implicitly incorporated in epidemiological models. This approach creates difficulty in parsing out the effects of adaptive behavior. We use an epidemiological-economic model of disease dynamics to explicitly model the trade-offs that drive person-to-person contact decisions. Results indicate that including adaptive human behavior significantly changes the predicted course of epidemics and that this inclusion has implications for parameter estimation and interpretation and for the development of social distancing policies. Acknowledging adaptive behavior requires a shift in thinking about epidemiological processes and parameters. PMID:21444809

  17. Adaptive human behavior in epidemiological models

    PubMed Central

    Fenichel, Eli P.; Castillo-Chavez, Carlos; Ceddia, M. G.; Chowell, Gerardo; Parra, Paula A. Gonzalez; Hickling, Graham J.; Holloway, Garth; Horan, Richard; Morin, Benjamin; Perrings, Charles; Springborn, Michael; Velazquez, Leticia; Villalobos, Cristina

    2011-01-01

    The science and management of infectious disease are entering a new stage. Increasingly public policy to manage epidemics focuses on motivating people, through social distancing policies, to alter their behavior to reduce contacts and reduce public disease risk. Person-to-person contacts drive human disease dynamics. People value such contacts and are willing to accept some disease risk to gain contact-related benefits. The cost–benefit trade-offs that shape contact behavior, and hence the course of epidemics, are often only implicitly incorporated in epidemiological models. This approach creates difficulty in parsing out the effects of adaptive behavior. We use an epidemiological–economic model of disease dynamics to explicitly model the trade-offs that drive person-to-person contact decisions. Results indicate that including adaptive human behavior significantly changes the predicted course of epidemics and that this inclusion has implications for parameter estimation and interpretation and for the development of social distancing policies. Acknowledging adaptive behavior requires a shift in thinking about epidemiological processes and parameters. PMID:21444809

  18. Development of large aperture composite adaptive optics

    NASA Astrophysics Data System (ADS)

    Kmetik, Viliam; Vitovec, Bohumil; Jiran, Lukas; Nemcova, Sarka; Zicha, Josef; Inneman, Adolf; Mikulickova, Lenka; Pavlica, Richard

    2015-01-01

    Large aperture composite adaptive optics for laser applications is investigated in cooperation of Institute of Plasma Physic, Department of Instrumentation and Control Engineering FME CTU and 5M Ltd. We are exploring opportunity of a large-size high-power-laser deformable-mirror production using a lightweight bimorph actuated structure with a composite core. In order to produce a sufficiently large operational free aperture we are developing new technologies for production of flexible core, bimorph actuator and deformable mirror reflector. Full simulation of a deformable-mirrors structure was prepared and validated by complex testing. A deformable mirror actuation and a response of a complicated structure are investigated for an accurate control of the adaptive optics. An original adaptive optics control system and a bimorph deformable mirror driver were developed. Tests of material samples, components and sub-assemblies were completed. A subscale 120 mm bimorph deformable mirror prototype was designed, fabricated and thoroughly tested. A large-size 300 mm composite-core bimorph deformable mirror was simulated and optimized, fabrication of a prototype is carried on. A measurement and testing facility is modified to accommodate large sizes optics.

  19. Contrarian behavior in a complex adaptive system

    NASA Astrophysics Data System (ADS)

    Liang, Y.; An, K. N.; Yang, G.; Huang, J. P.

    2013-01-01

    Contrarian behavior is a kind of self-organization in complex adaptive systems (CASs). Here we report the existence of a transition point in a model resource-allocation CAS with contrarian behavior by using human experiments, computer simulations, and theoretical analysis. The resource ratio and system predictability serve as the tuning parameter and order parameter, respectively. The transition point helps to reveal the positive or negative role of contrarian behavior. This finding is in contrast to the common belief that contrarian behavior always has a positive role in resource allocation, say, stabilizing resource allocation by shrinking the redundancy or the lack of resources. It is further shown that resource allocation can be optimized at the transition point by adding an appropriate size of contrarians. This work is also expected to be of value to some other fields ranging from management and social science to ecology and evolution.

  20. Grid adaptation using chimera composite overlapping meshes

    NASA Technical Reports Server (NTRS)

    Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

    1994-01-01

    The objective of this paper is to perform grid adaptation using composite overlapping meshes in regions of large gradient to accurately capture the salient features during computation. The chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using trilinear interpolation. Application to the Euler equations for shock reflections and to shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well-resolved.

  1. Grid adaptation using Chimera composite overlapping meshes

    NASA Technical Reports Server (NTRS)

    Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

    1993-01-01

    The objective of this paper is to perform grid adaptation using composite over-lapping meshes in regions of large gradient to capture the salient features accurately during computation. The Chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using tri-linear interpolation. Applications to the Euler equations for shock reflections and to a shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well resolved.

  2. Grid adaption using Chimera composite overlapping meshes

    NASA Technical Reports Server (NTRS)

    Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

    1993-01-01

    The objective of this paper is to perform grid adaptation using composite over-lapping meshes in regions of large gradient to capture the salient features accurately during computation. The Chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using tri-linear interpolation. Applications to the Euler equations for shock reflections and to a shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well resolved.

  3. Adaptive Behavior of Children and Adolescents with Visual Impairments

    ERIC Educational Resources Information Center

    Papadopoulos, Konstantinos; Metsiou, Katerina; Agaliotis, Ioannis

    2011-01-01

    The present study explored the total adaptive behavior of children and adolescents with visual impairments, as well as their adaptive behavior in each of the domains of Communication, Daily Living Skills, and Socialization. Moreover, the predictors of the performance and developmental delay in adaptive behavior were investigated. Instrumentation…

  4. Adaptive Behavior Evaluation Scale: School Version Technical Manual. Revised.

    ERIC Educational Resources Information Center

    McCarney, Stephen B.

    This test manual provides information on the Adaptive Behavior Education Scale-Revised (ABES-R), a 25-minute behavior scale designed to evaluate adaptive skills in students with behavioral, learning, and intellectual disabilities, including educationally relevant behavior which may be identified as contributing to more appropriate diagnosis,…

  5. Adaptive Behavior Evaluation Scale: Home Version Technical Manual. Revised.

    ERIC Educational Resources Information Center

    McCarney, Stephen B.

    This test manual provides information on the Adaptive Behavior Education Scale-Home Version (ABES), a 25-minute behavior scale designed to evaluate adaptive skills in students with behavioral, learning, and intellectual disabilities, including educationally relevant behavior which may be identified as contributing to more appropriate diagnosis,…

  6. Effects of light curing method and resin composite composition on composite adaptation to the cavity wall.

    PubMed

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2014-01-01

    This study aimed to evaluate the effects of the light curing method and resin composite composition on marginal sealing and resin composite adaptation to the cavity wall. Cylindrical cavities were prepared on the buccal or lingual cervical regions. The teeth were restored using Clearfil Liner Bond 2V adhesive system and filled with Clearfil Photo Bright or Palfique Estelite resin composite. The resins were cured using the conventional or slow-start light curing method. After thermal cycling, the specimens were subjected to a dye penetration test. The slow-start curing method showed better resin composite adaptation to the cavity wall for both composites. Furthermore, the slow-start curing method resulted in significantly improved dentin marginal sealing compared with the conventional method for Clearfil Photo Bright. The light-cured resin composite, which exhibited increased contrast ratios duringpolymerization, seems to suggest high compensation for polymerization contraction stress when using the slow-start curing method. PMID:24988883

  7. Adaptive Behavior and Problem Behavior in Young Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Hahn, Laura J.; Fidler, Deborah J.; Hepburn, Susan L.

    2014-01-01

    The present study compares the adaptive behavior profile of 18 young children with Williams syndrome (WS) and a developmentally matched group of 19 children with developmental disabilities and examines the relationship between adaptive behavior and problem behaviors in WS. Parents completed the Vineland Adaptive Behavioral Scales--Interview…

  8. Anomalous human behavior detection: an adaptive approach

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Coen; Halma, Arvid; Schutte, Klamer

    2013-05-01

    Detection of anomalies (outliers or abnormal instances) is an important element in a range of applications such as fault, fraud, suspicious behavior detection and knowledge discovery. In this article we propose a new method for anomaly detection and performed tested its ability to detect anomalous behavior in videos from DARPA's Mind's Eye program, containing a variety of human activities. In this semi-unsupervised task a set of normal instances is provided for training, after which unknown abnormal behavior has to be detected in a test set. The features extracted from the video data have high dimensionality, are sparse and inhomogeneously distributed in the feature space making it a challenging task. Given these characteristics a distance-based method is preferred, but choosing a threshold to classify instances as (ab)normal is non-trivial. Our novel aproach, the Adaptive Outlier Distance (AOD) is able to detect outliers in these conditions based on local distance ratios. The underlying assumption is that the local maximum distance between labeled examples is a good indicator of the variation in that neighborhood, and therefore a local threshold will result in more robust outlier detection. We compare our method to existing state-of-art methods such as the Local Outlier Factor (LOF) and the Local Distance-based Outlier Factor (LDOF). The results of the experiments show that our novel approach improves the quality of the anomaly detection.

  9. Adaptive Behavior in Children with Fragile X Syndrome.

    ERIC Educational Resources Information Center

    Hatton, Deborah D.; Wheeler, Anne C.; Skinner, Martie L.; Bailey, Donald B.; Sullivan, Kelly M.; Roberts, Jane E.; Mirrett, Penny; Clark, Renee D.

    2003-01-01

    Adaptive behavior was measured over time in 70 children, ages 1 to 12 years, with fragile X syndrome. With a mean of 4.4 assessments per child, adaptive behavior skills increased steadily and gradually over time. Children with less autistic behavior and higher percentages of the fragile X mental retardation gene protein showed better performance…

  10. Cross-National Assessment of Adaptive Behavior in Three Countries

    ERIC Educational Resources Information Center

    Oakland, Thomas; Iliescu, Dragos; Chen, Hsin-Yi; Chen, Juliet Honglei

    2013-01-01

    Measures of adaptive behaviors provide an important tool in the repertoire of clinical and school/educational psychologists. Measures that assess adaptive behaviors typically have been built in Western cultures and developed in light of behaviors common to them. Nevertheless, these measures are used elsewhere despite a paucity of data that examine…

  11. Communicating to Farmers about Skin Cancer: The Behavior Adaptation Model.

    ERIC Educational Resources Information Center

    Parrott, Roxanne; Monahan, Jennifer; Ainsworth, Stuart; Steiner, Carol

    1998-01-01

    States health campaign messages designed to encourage behavior adaptation have greater likelihood of success than campaigns promoting avoidance of at-risk behaviors that cannot be avoided. Tests a model of health risk behavior using four different behaviors in a communication campaign aimed at reducing farmers' risk for skin cancer--questions…

  12. Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Gao, Xiujie; Burton, Deborah; Turner, Travis L.; Brinson, Catherine

    2005-01-01

    Shape memory alloy hybrid composites with adaptive-stiffening or morphing functions are simulated using finite element analysis. The composite structure is a laminated fiber-polymer composite beam with embedded SMA ribbons at various positions with respect to the neutral axis of the beam. Adaptive stiffening or morphing is activated via selective resistance heating of the SMA ribbons or uniform thermal loads on the beam. The thermomechanical behavior of these composites was simulated in ABAQUS using user-defined SMA elements. The examples demonstrate the usefulness of the methods for the design and simulation of SMA hybrid composites. Keywords: shape memory alloys, Nitinol, ABAQUS, finite element analysis, post-buckling control, shape control, deflection control, adaptive stiffening, morphing, constitutive modeling, user element

  13. Assessing Minority Students: The Role of Adaptive Behavior Scales.

    ERIC Educational Resources Information Center

    Cervantes, Hermes; Baca, Leonard M.

    1979-01-01

    Adaptive behavior scales can be very helpful in the overall assessment of minority children. In some states they are mandatory. Their weaknesses, particularly with the AAMD Adaptive Behavior Scale, are sampling bias and appropriateness in the areas of culture, language, and socioeconomic status. (Author)

  14. Development and Standardization of the Diagnostic Adaptive Behavior Scale: Application of Item Response Theory to the Assessment of Adaptive Behavior

    ERIC Educational Resources Information Center

    Tassé, Marc J.; Schalock, Robert L.; Thissen, David; Balboni, Giulia; Bersani, Henry, Jr.; Borthwick-Duffy, Sharon A.; Spreat, Scott; Widaman, Keith F.; Zhang, Dalun; Navas, Patricia

    2016-01-01

    The Diagnostic Adaptive Behavior Scale (DABS) was developed using item response theory (IRT) methods and was constructed to provide the most precise and valid adaptive behavior information at or near the cutoff point of making a decision regarding a diagnosis of intellectual disability. The DABS initial item pool consisted of 260 items. Using IRT…

  15. Fiber Composite Sandwich Thermostructural Behavior: Computational Simulation

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Aiello, R. A.; Murthy, P. L. N.

    1986-01-01

    Several computational levels of progressive sophistication/simplification are described to computationally simulate composite sandwich hygral, thermal, and structural behavior. The computational levels of sophistication include: (1) three-dimensional detailed finite element modeling of the honeycomb, the adhesive and the composite faces; (2) three-dimensional finite element modeling of the honeycomb assumed to be an equivalent continuous, homogeneous medium, the adhesive and the composite faces; (3) laminate theory simulation where the honeycomb (metal or composite) is assumed to consist of plies with equivalent properties; and (4) derivations of approximate, simplified equations for thermal and mechanical properties by simulating the honeycomb as an equivalent homogeneous medium. The approximate equations are combined with composite hygrothermomechanical and laminate theories to provide a simple and effective computational procedure for simulating the thermomechanical/thermostructural behavior of fiber composite sandwich structures.

  16. Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Gao, Xiu-Jie; Turner, Travis L.; Burton, Deborah; Brinson, L. Catherine

    2005-01-01

    The usage of shape memory materials has extended rapidly to many fields, including medical devices, actuators, composites, structures and MEMS devices. For these various applications, shape memory alloys (SMAs) are available in various forms: bulk, wire, ribbon, thin film, and porous. In this work, the focus is on SMA hybrid composites with adaptive-stiffening or morphing functions. These composites are created by using SMA ribbons or wires embedded in a polymeric based composite panel/beam. Adaptive stiffening or morphing is activated via selective resistance heating or uniform thermal loads. To simulate the thermomechanical behavior of these composites, a SMA model was implemented using ABAQUS user element interface and finite element simulations of the systems were studied. Several examples are presented which show that the implemented model can be a very useful design and simulation tool for SMA hybrid composites.

  17. Parents' Reports on the Child Adaptive Behavior Inventory Predict 4-Year-Olds' Playground Behavior.

    ERIC Educational Resources Information Center

    McHale, James P.; Neugebauer, Alyson

    1998-01-01

    Examined the effectiveness of parental reports of their preschool children's social adaptation outside the home as an indicator of children's behavior. Parent responses on the Child Adaptive Behavior Inventory, which assesses both competencies and difficulties with adaptation, were compared to evaluations by trained observers. Parents were found…

  18. Fast adaptive composite grid methods on distributed parallel architectures

    NASA Technical Reports Server (NTRS)

    Lemke, Max; Quinlan, Daniel

    1992-01-01

    The fast adaptive composite (FAC) grid method is compared with the adaptive composite method (AFAC) under variety of conditions including vectorization and parallelization. Results are given for distributed memory multiprocessor architectures (SUPRENUM, Intel iPSC/2 and iPSC/860). It is shown that the good performance of AFAC and its superiority over FAC in a parallel environment is a property of the algorithm and not dependent on peculiarities of any machine.

  19. Investigations on the magnetization behavior of magnetic composite particles

    NASA Astrophysics Data System (ADS)

    Eichholz, Christian; Knoll, Johannes; Lerche, Dietmar; Nirschl, Hermann

    2014-11-01

    In life sciences the application of surface functionalized magnetic composite particles is establishing in diagnostics and in downstream processing of modern biotechnology. These magnetic composite particles consist of non-magnetic material, e.g. polystyrene, which serves as a matrix for the second magnetic component, usually colloidal magnetite. Because of the multitude of magnetic cores these magnetic beads show a complex magnetization behavior which cannot be described with the available approaches for homogeneous magnetic material. Therefore, in this work a new model for the magnetization behavior of magnetic composite particles is developed. By introducing an effective magnetization and considering an overall demagnetization factor the deviation of the demagnetization of homogeneously magnetized particles is taken into account. Calculated and experimental results show a good agreement which allows for the verification of the adapted model of particle magnetization. Besides, a newly developed magnetic analyzing centrifuge is used for the characterization of magnetic composite particle systems. The experimental results, also used for the model verification, give both, information about the magnetic properties and the interaction behavior of particle systems. By adding further components to the particle solution, such as salts or proteins, industrial relevant systems can be reconstructed. The analyzing tool can be used to adapt industrial processes without time-consuming preliminary tests with large samples in the process equipments.

  20. Pressure behavior of laterally composite reservoirs

    SciTech Connect

    Kuchuk, F.J.; Habashy, T.

    1997-03-01

    This paper presents a new general method for solving the pressure diffusion equation in laterally composite reservoirs, where rock and fluid properties may change laterally as a function of y in the x-y plane. Composite systems can be encountered as a result of many different types of depositional and tectonic processes. For example, meandering point bar reservoirs or reservoirs with edgewater encroachment are examples of such systems. The new solution method presented is based on the reflection-transmission concept of electromagnetics to solve fluid-flow problems in 3D nonhomogeneous reservoirs, where heterogeneity is in only one (y) direction. A general Green`s function for a point source in 3D laterally composite systems is developed by using the reflection-transmission method. The solutions in the Laplace transform domain are then developed from the Green`s function for the pressure behavior of specific composite reservoirs. The solution method can also be applied to many different types of wells, such as vertical, fractured, and horizontal in composite reservoirs. The pressure behavior of a few well-known laterally composite systems are investigated. It is shown that a network of partially communicating faults and fractures in porous medium can be modeled as composite systems. It is also shown that the existing solutions for a partially communicating fault are not valid when the fault permeability is substantially larger than the formation permeability. The derivative plots are presented for selected faulted, fractured, channel, and composite reservoirs as diagnostic tools for well-test interpretation. It is also shown that if the composite system`s permeability varies moderately in the x or y direction, it exhibits a homogeneous system behavior. However, it does not yield the system`s average permeability. Furthermore, the composite systems with distributed low-permeability zones behave as if the system has many two no-flow boundaries.

  1. Panel V: Adaptive Health Behaviors Among Ethnic Minorities

    PubMed Central

    Bagley, Shirley P.; Angel, Ronald; Dilworth-Anderson, Peggye; Liu, William; Schinke, Steven

    2006-01-01

    Race, ethnicity, and cultural attitudes and practices are among the variables that influence health behaviors, including adaptive health behaviors. The following discussions highlight the important role of social conditions in shaping health behaviors and the central role of family in promoting health across the Asian, Hispanic, Native American, and African American ethnic groups. Factors that may lead to health-damaging behaviors are also discussed. The need for additional research that identifies correlations among physiological, social, and behavioral factors and health behaviors, as well as underlying mechanisms, is called for. PMID:8654341

  2. Prefrontal executive function and adaptive behavior in complex environments.

    PubMed

    Koechlin, Etienne

    2016-04-01

    The prefrontal cortex (PFC) subserves higher cognitive abilities such as planning, reasoning and creativity. Here we review recent findings from both empirical and theoretical studies providing new insights about these cognitive abilities and their neural underpinnings in the PFC as overcoming key adaptive limitations in reinforcement learning. We outline a unified theoretical framework describing the PFC function as implementing an algorithmic solution approximating statistically optimal, but computationally intractable, adaptive processes. The resulting PFC functional architecture combines learning, planning, reasoning and creativity processes for balancing exploitation and exploration behaviors and optimizing behavioral adaptations in uncertain, variable and open-ended environments. PMID:26687618

  3. Adapting Behavioral Interventions for Social Media Delivery

    PubMed Central

    Waring, Molly E; May, Christine N; Ding, Eric Y; Kunz, Werner H; Hayes, Rashelle; Oleski, Jessica L

    2016-01-01

    Patients are increasingly using online social networks (ie, social media) to connect with other patients and health care professionals—a trend called peer-to-peer health care. Because online social networks provide a means for health care professionals to communicate with patients, and for patients to communicate with each other, an opportunity exists to use social media as a modality to deliver behavioral interventions. Social media-delivered behavioral interventions have the potential to reduce the expense of behavioral interventions by eliminating visits, as well as increase our access to patients by becoming embedded in their social media feeds. Trials of online social network-delivered behavioral interventions have shown promise, but much is unknown about intervention development and methodology. In this paper, we discuss the process by which investigators can translate behavioral interventions for social media delivery. We present a model that describes the steps and decision points in this process, including the necessary training and reporting requirements. We also discuss issues pertinent to social media-delivered interventions, including cost, scalability, and privacy. Finally, we identify areas of research that are needed to optimize this emerging behavioral intervention modality. PMID:26825969

  4. Adapting Behavioral Interventions for Social Media Delivery.

    PubMed

    Pagoto, Sherry; Waring, Molly E; May, Christine N; Ding, Eric Y; Kunz, Werner H; Hayes, Rashelle; Oleski, Jessica L

    2016-01-01

    Patients are increasingly using online social networks (ie, social media) to connect with other patients and health care professionals--a trend called peer-to-peer health care. Because online social networks provide a means for health care professionals to communicate with patients, and for patients to communicate with each other, an opportunity exists to use social media as a modality to deliver behavioral interventions. Social media-delivered behavioral interventions have the potential to reduce the expense of behavioral interventions by eliminating visits, as well as increase our access to patients by becoming embedded in their social media feeds. Trials of online social network-delivered behavioral interventions have shown promise, but much is unknown about intervention development and methodology. In this paper, we discuss the process by which investigators can translate behavioral interventions for social media delivery. We present a model that describes the steps and decision points in this process, including the necessary training and reporting requirements. We also discuss issues pertinent to social media-delivered interventions, including cost, scalability, and privacy. Finally, we identify areas of research that are needed to optimize this emerging behavioral intervention modality. PMID:26825969

  5. Cultural Adaptations of Behavioral Health Interventions: A Progress Report

    ERIC Educational Resources Information Center

    Barrera, Manuel, Jr.; Castro, Felipe G.; Strycker, Lisa A.; Toobert, Deborah J.

    2013-01-01

    Objective: To reduce health disparities, behavioral health interventions must reach subcultural groups and demonstrate effectiveness in improving their health behaviors and outcomes. One approach to developing such health interventions is to culturally adapt original evidence-based interventions. The goals of the article are to (a) describe…

  6. Hierarchical nonlinear behavior of hot composite structures

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.; Singhal, S. N.

    1993-01-01

    Hierarchical computational procedures are described to simulate the multiple scale thermal/mechanical behavior of high temperature metal matrix composites (HT-MMC) in the following three broad areas: (1) behavior of HT-MMC's from micromechanics to laminate via METCAN (Metal Matrix Composite Analyzer), (2) tailoring of HT-MMC behavior for optimum specific performance via MMLT (Metal Matrix Laminate Tailoring), and (3) HT-MMC structural response for hot structural components via HITCAN (High Temperature Composite Analyzer). Representative results from each area are presented to illustrate the effectiveness of computational simulation procedures and accompanying computer codes. The sample case results show that METCAN can be used to simulate material behavior such as the entire creep span; MMLT can be used to concurrently tailor the fabrication process and the interphase layer for optimum performance such as minimum residual stresses; and HITCAN can be used to predict the structural behavior such as the deformed shape due to component fabrication. These codes constitute virtual portable desk-top test laboratories for characterizing HT-MMC laminates, tailoring the fabrication process, and qualifying structural components made from them.

  7. Adaptive and maladaptive behavior of idiots savants.

    PubMed

    Duckett, J

    1977-11-01

    A comparison was made of 25 institutionalized idiots savants and a control group of institutionalized retarded persons matched for age, sex, IQ, and length of institutionalization. As a group, idiots savants were found to be somewhat more disturbed and disturbing than their peers, although they did not show extreme emotional disturbance nor reflect a clear behavioral profile. PMID:930969

  8. Mouse Behavior: Conjectures about Adaptations for Survival.

    ERIC Educational Resources Information Center

    Rop, Charles

    2001-01-01

    Presents an experiment on mouse behavior in which students learn to observe, pay attention to details, record field notes, and ask questions about their observations. Uses a white mouse to eliminate the risk of disease that a wild rodent might carry. Lists materials, set up, and procedure. (YDS)

  9. Adaptive Prediction Error Coding in the Human Midbrain and Striatum Facilitates Behavioral Adaptation and Learning Efficiency.

    PubMed

    Diederen, Kelly M J; Spencer, Tom; Vestergaard, Martin D; Fletcher, Paul C; Schultz, Wolfram

    2016-06-01

    Effective error-driven learning benefits from scaling of prediction errors to reward variability. Such behavioral adaptation may be facilitated by neurons coding prediction errors relative to the standard deviation (SD) of reward distributions. To investigate this hypothesis, we required participants to predict the magnitude of upcoming reward drawn from distributions with different SDs. After each prediction, participants received a reward, yielding trial-by-trial prediction errors. In line with the notion of adaptive coding, BOLD response slopes in the Substantia Nigra/Ventral Tegmental Area (SN/VTA) and ventral striatum were steeper for prediction errors occurring in distributions with smaller SDs. SN/VTA adaptation was not instantaneous but developed across trials. Adaptive prediction error coding was paralleled by behavioral adaptation, as reflected by SD-dependent changes in learning rate. Crucially, increased SN/VTA and ventral striatal adaptation was related to improved task performance. These results suggest that adaptive coding facilitates behavioral adaptation and supports efficient learning. PMID:27181060

  10. Driver's adaptive glance behavior to in-vehicle information systems.

    PubMed

    Peng, Yiyun; Boyle, Linda Ng

    2015-12-01

    The purpose of this study was to examine the adaptive behavior of drivers as they engage with in-vehicle devices over time and in varying driving situations. Behavioral adaptation has been shown to occur among drivers after prolonged use of in-vehicle devices, but few studies have examined drivers' risk levels across different driving demands. A multi-day simulator study was conducted with 28 young drivers (under 30 years old) as they engaged in different text entry and reading tasks while driving in two different traffic conditions. Cluster analysis was used to categorize drivers based on their risk levels and random coefficient models were used to assess changes in drivers' eye glance behavior. Glance duration significantly increased over time while drivers were performing text entry tasks but not for text reading tasks. High-risk drivers had longer maximum eyes-off-road when performing long text entry tasks compared to low-risk drivers, and this difference increased over time. The traffic condition also had a significant impact on drivers' glance behavior. This study suggests that drivers may exhibit negative behavioral adaptation as they become more comfortable with using in-vehicle technologies over time. Results of this paper may provide guidance for the design of in-vehicle devices that adapt based on the context of the situation. It also demonstrates that random coefficient models can be used to obtain better estimations of driver behavior when there are large individual differences. PMID:26406538

  11. High Strain Rate Behavior of Polyurea Compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant; Milby, Christopher

    2011-06-01

    Polyurea has been gaining importance in recent years due to its impact resistance properties. The actual compositions of this viscoelastic material must be tailored for specific use. It is therefore imperative to study the effect of variations in composition on the properties of the material. High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with titanium bars. The polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. The materials have been tested up to strain rates of 6000/s. Results from these tests have shown interesting trends on the high rate behavior. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Refinement in experimental methods and comparison of results using aluminum Split Hopkinson Bar is presented.

  12. Prediction of composite hygral behavior made simple

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1982-01-01

    A convenient procedure is described to determine the hygral behavior (moisture expansion coefficients and moisture stresses) of angleplied fiber composites using a pocket calculator. The procedure consists of equations and appropriate graphs for various (+ or - theta) ply combinations. These graphs present reduced stiffness and moisture expansion coefficients as functions of (+ or - theta) in order to simplify and expedite the use of the equations. The procedure is applicable to all types of balanced, symmetric fiber composites including interply and intraply hybrids. The versatility and generality of the procedure is illustrated using several step-by-step numerical examples.

  13. Prediction of composite thermal behavior made simple

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1981-01-01

    A convenient procedure is described to determine the thermal behavior (thermal expansion coefficients and thermal stresses) of angleplied fiber composites using a pocket calculator. The procedure consists of equations and appropriate graphs for various ( + or - theta) ply combinations. These graphs present reduced stiffness and thermal expansion coefficients as functions of (+ or - theta) in order to simplify and expedite the use of the equations. The procedure is applicable to all types of balanced, symmetric fiber composites including interply and intraply hybrids. The versatility and generality of the procedure is illustrated using several step-by-step numerical examples.

  14. Prediction of composite hygral behavior made simple

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1982-01-01

    A convenient procedure is described to determine the hygral behavior (moisture expansion coefficients and moisture stresses) of angleplied fiber composites using a pocket calculator. The procedure consists of equations and appropriate graphs for various (+ or - theta) ply combinations. These graphs present reduced stiffness and moisture expansion coefficients as functions of (+ or - theta) in order to simplify and expedite the use of the equations. The procedure is applicable to all types of balanced, symmetric fiber composites including interply and intraply hybrids. The versatility and generality of the procedure is illustrated using several step-by-step numerical examples. Previously announced in STAR as N82-16181

  15. Linking Individual and Collective Behavior in Adaptive Social Networks

    NASA Astrophysics Data System (ADS)

    Pinheiro, Flávio L.; Santos, Francisco C.; Pacheco, Jorge M.

    2016-03-01

    Adaptive social structures are known to promote the evolution of cooperation. However, up to now the characterization of the collective, population-wide dynamics resulting from the self-organization of individual strategies on a coevolving, adaptive network has remained unfeasible. Here we establish a (reversible) link between individual (micro)behavior and collective (macro)behavior for coevolutionary processes. We demonstrate that an adaptive network transforms a two-person social dilemma locally faced by individuals into a collective dynamics that resembles that associated with an N -person coordination game, whose characterization depends sensitively on the relative time scales between the entangled behavioral and network evolutions. In particular, we show that the faster the relative rate of adaptation of the network, the smaller the critical fraction of cooperators required for cooperation to prevail, thus establishing a direct link between network adaptation and the evolution of cooperation. The framework developed here is general and may be readily applied to other dynamical processes occurring on adaptive networks, notably, the spreading of contagious diseases or the diffusion of innovations.

  16. Cultural Adaptations of Behavioral Health Interventions: A Progress Report

    PubMed Central

    Barrera, Manuel

    2014-01-01

    Objective To reduce health disparities, behavioral health interventions must reach subcultural groups and demonstrate effectiveness in improving their health behaviors and outcomes. One approach to developing such health interventions is to culturally adapt original evidence-based interventions. The goals of the paper are to (a) describe consensus on the stages involved in developing cultural adaptations, (b) identify common elements in cultural adaptations, (c) examine evidence on the effectiveness of culturally enhanced interventions for various health conditions, and (d) pose questions for future research. Method Influential literature from the past decade was examined to identify points of consensus. Results There is agreement that cultural adaptation can be organized into five stages: information gathering, preliminary design, preliminary testing, refinement, and final trial. With few exceptions, reviews of several health conditions (e.g., AIDS, asthma, diabetes) concluded that culturally enhanced interventions are more effective in improving health outcomes than usual care or other control conditions. Conclusion Progress has been made in establishing methods for conducting cultural adaptations and providing evidence of their effectiveness. Future research should include evaluations of cultural adaptations developed in stages, tests to determine the effectiveness of cultural adaptations relative to the original versions, and studies that advance our understanding of cultural constructs’ contributions to intervention engagement and efficacy. PMID:22289132

  17. Building team adaptive capacity: the roles of sensegiving and team composition.

    PubMed

    Randall, Kenneth R; Resick, Christian J; DeChurch, Leslie A

    2011-05-01

    The current study draws on motivated information processing in groups theory to propose that leadership functions and composition characteristics provide teams with the epistemic and social motivation needed for collective information processing and strategy adaptation. Three-person teams performed a city management decision-making simulation (N=74 teams; 222 individuals). Teams first managed a simulated city that was newly formed and required growth strategies and were then abruptly switched to a second simulated city that was established and required revitalization strategies. Consistent with hypotheses, external sensegiving and team composition enabled distinct aspects of collective information processing. Sensegiving prompted the emergence of team strategy mental models (i.e., cognitive information processing); psychological collectivism facilitated information sharing (i.e., behavioral information processing); and cognitive ability provided the capacity for both the cognitive and behavioral aspects of collective information processing. In turn, team mental models and information sharing enabled reactive strategy adaptation. PMID:21319876

  18. Adaptive composites with embedded NiTiCu wires

    NASA Astrophysics Data System (ADS)

    Balta-Neumann, J. Antonio; Michaud, Veronique J.; Parlinska, Magdelena; Gotthardt, Rolf; Manson, Jan-Anders E.

    2001-07-01

    Adaptive composites have been produced by embedding prestrained shape memory alloy (SMA) wires into an epoxy matrix, reinforced with aramid fibers. These materials demonstrate attractive effects such as shape change or a shift in the vibration frequency upon activation. When heated above their transformation temperature, the wires' strain recovery is confined, and recovery stresses are generated. As a result, if the wires are placed along the neutral axis of a composite beam, a shift in resonance vibration frequency can be observed. To optimize the design of such composites, the matrix - SMA wire interfacial shear strength has been analyzed with the pull out testing technique. It is shown that the nature of the wire surface influences the interfacial shear strength, and that satisfactory results are obtained for SMA wires with a thin oxide layer. Composite samples consisting of two different types of pre- strained NiTiCu wires embedded in either pure epoxy matrix or Kevlar-epoxy matrix were produced. The recovery force and vibration response of composites were measured in a clamped-clamped configuration, to assess the effect of wire type and volume fraction. The results are highly reproducible in all cases with a narrow hysteresis loop, which makes NiTiCu wires good candidates for adaptive composites. The recovery forces increase with the volume fraction of the embedded wires, are higher when the wires are embedded in a low CTE matrix and, at a given temperature, are higher when the wire transformation temperature is lower.

  19. Endogenous Nuclear RNAi Mediates Behavioral Adaptation to Odor

    PubMed Central

    Juang, Bi-Tzen; Gu, Chen; Starnes, Linda; Palladino, Francesca; Goga, Andrei; Kennedy, Scott; L'Etoile, Noelle D.

    2014-01-01

    Summary Most eukaryotic cells express small regulatory RNAs. The purpose of one class, the somatic endogenous siRNAs (endo-siRNAs) remains unclear. Here we show the endo-siRNA pathway promotes odor adaptation in C. elegans AWC olfactory neurons. In adaptation, the nuclear Argonaute NRDE-3, which acts in AWC, is loaded with siRNAs targeting odr-1, a gene who's down regulation is required for adaptation. Concomitant with increased odr-1 siRNA in AWC, we observe increased binding of the HP1 homolog HPL-2 at the odr-1 locus in AWC and reduced odr-1 mRNA in adapted animals. Phosphorylation of HPL-2, an in vitro substrate of the EGL-4 kinase that promotes adaption, is necessary and sufficient for behavioral adaptation. Thus, environmental stimulation amplifies an endo-siRNA negative feedback loop to dynamically repress cognate gene expression and shape behavior. This class of siRNA may act broadly as a rheostat allowing prolonged stimulation to dampen gene expression and promote cellular memory formation. PMID:23993094

  20. Adaptive Behavior in Toddlers under Two with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Paul, Rhea; Loomis, Rebecca; Chawarska, Katarzyna

    2014-01-01

    The Vineland Adaptive Behavior Scale was administered to 54 children diagnosed with autism spectrum disorder (ASD) before age 2, and a matching group of 18 toddlers with developmental delay (DD). The group with ASD was more impaired on all scales of the Vineland than DD peers. When 18 ASD/DD pairs very closely matched on age, verbal and nonverbal…

  1. Adaptations for Rural Behavior Disordered Pupils in the Mainstream.

    ERIC Educational Resources Information Center

    Wood, Judy W.; And Others

    1988-01-01

    Discusses instructional modifications to increase the academic success of rural behavior-disordered students in regular classes. Describes adaptations of teaching mode, media use, presentation of academic content, textbook content and organization, and test construction and administration. Contains 10 references. (SV)

  2. The Adaptive Behavior Scale: A Study of Criterion Validity.

    ERIC Educational Resources Information Center

    Spreat, Scott

    1980-01-01

    The validity of the Adaptive Behavior Scale (ABS) for placement purposes was estimated using as Ss 95 formerly institutionalized retarded persons, 97 institutional residents referred for discharge, and 178 institutional residents. Results suggest that knowledge of an individual's ABS scores would enable a test user to make valid estimates of group…

  3. Amyotrophic Lateral Sclerosis: An Introduction to Psychosocial and Behavioral Adaptations.

    ERIC Educational Resources Information Center

    Hoffman, R. Leigh; Decker, Thomas W.

    1993-01-01

    Defines amyotrophic lateral sclerosis (ALS) as motor-neuron disease that is terminal. Discusses symptoms associated with ALS and identifies treatment options. Reviews psychological and behavioral adaptations in regard to ALS clients, their families, and professionals who work with them. Discusses support groups as method of reducing stress for ALS…

  4. Sensory Processing Subtypes in Autism: Association with Adaptive Behavior

    ERIC Educational Resources Information Center

    Lane, Alison E.; Young, Robyn L.; Baker, Amy E. Z.; Angley, Manya T.

    2010-01-01

    Children with autism are frequently observed to experience difficulties in sensory processing. This study examined specific patterns of sensory processing in 54 children with autistic disorder and their association with adaptive behavior. Model-based cluster analysis revealed three distinct sensory processing subtypes in autism. These subtypes…

  5. Coupled multi-disciplinary composites behavior simulation

    NASA Technical Reports Server (NTRS)

    Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.

    1993-01-01

    The capabilities of the computer code CSTEM (Coupled Structural/Thermal/Electro-Magnetic Analysis) are discussed and demonstrated. CSTEM computationally simulates the coupled response of layered multi-material composite structures subjected to simultaneous thermal, structural, vibration, acoustic, and electromagnetic loads and includes the effect of aggressive environments. The composite material behavior and structural response is determined at its various inherent scales: constituents (fiber/matrix), ply, laminate, and structural component. The thermal and mechanical properties of the constituents are considered to be nonlinearly dependent on various parameters such as temperature and moisture. The acoustic and electromagnetic properties also include dependence on vibration and electromagnetic wave frequencies, respectively. The simulation is based on a three dimensional finite element analysis in conjunction with composite mechanics and with structural tailoring codes, and with acoustic and electromagnetic analysis methods. An aircraft engine composite fan blade is selected as a typical structural component to demonstrate the CSTEM capabilities. Results of various coupled multi-disciplinary heat transfer, structural, vibration, acoustic, and electromagnetic analyses for temperature distribution, stress and displacement response, deformed shape, vibration frequencies, mode shapes, acoustic noise, and electromagnetic reflection from the fan blade are discussed for their coupled effects in hot and humid environments. Collectively, these results demonstrate the effectiveness of the CSTEM code in capturing the coupled effects on the various responses of composite structures subjected to simultaneous multiple real-life loads.

  6. Adaptive female-mimicking behavior in a scorpionfly.

    PubMed

    Thornhill, R

    1979-07-27

    This study provides a clear example of female-mimicking behavior by males in insects and evaluates quantitatively the adaptive significance of this behavior, which is poorly understood in many other organisms. Males of Hylobittacus apicalis provide females with a prey arthropod during copulation. Some males mimic female behavior when interacting with males that have captured nuptial prey, resulting in males stealing prey which they will use for copulation. Males that pirate prey copulate more frequently and probably incur fewer predation-related risks. PMID:17790854

  7. Reliability and Validity of the Vietnamese Vineland Adaptive Behavior Scales with Preschool-Age Children

    ERIC Educational Resources Information Center

    Goldberg, Michael R.; Dill, Charles A.; Shin, Jin Y.; Nhan, Nguyen Viet

    2009-01-01

    This study was conducted to examine an adaptation of the Vineland Adaptive Behavior Scale (VABS) [Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (1984). "The Vineland Adaptive Behavior Scales." Circle Pines, MN: America Guidance Service; Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (2005). "Vineland Adaptive Behavior Scales Second Edition…

  8. Compression behavior of unidirectional fibrous composite

    NASA Technical Reports Server (NTRS)

    Sinclair, J. H.; Chamis, C. C.

    1982-01-01

    The longitudinal compression behavior of unidirectional fiber composites is investigated using a modified Celanese test method with thick and thin test specimens. The test data obtained are interpreted using the stress/strain curves from back-to-back strain gages, examination of fracture surfaces by scanning electron microscope, and predictive equations for distinct failure modes including fiber compression failure, Euler buckling, delamination, and flexure. The results show that the longitudinal compression fracture is induced by a combination of delamination, flexure, and fiber tier breaks. No distinct fracture surface characteristics can be associated with unique failure modes. An equation is described which can be used to extract the longitudinal compression strength knowing the longitudinal tensile and flexural strengths of the same composite system.

  9. Composite behaviors of dual meminductor circuits

    NASA Astrophysics Data System (ADS)

    Zheng, Ci-Yan; Yu, Dong-Sheng; Liang, Yan; Chen, Meng-Ke

    2015-11-01

    This paper focuses on analyzing the composite dynamic behaviors of two meminductors in serial and parallel connections with different polarities. Based on the constitutive relations, two time-integral-of-flux (TIF) controlled meminductors are adopted to theoretically demonstrate the variation of memductance in terms of TIF, charge, flux, and current. By utilizing a floating memristor-less meminductor emulator, the theoretical analysis reported in this paper is confirmed via a PSPICE simulation study and hardware experiment. Good agreement among theoretical analysis, simulation, and hardware validation confirms that dual meminductor circuits in composite connections behave as a new meminductor with higher complexity. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. 2013QNB28.)

  10. Structural behavior of composites with progressive fracture

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C.; Murthy, Pappu L. N.

    1990-01-01

    Structural characteristics such as natural frequencies and buckling loads with corresponding mode shapes were investigated during progressive fracture of multilayer, angle-plied polymer matrix composites. A computer program was used to generate the numerical results for overall mechanical response of damaged composites. Variations in structural characteristics as a function of the previously applied loading were studied. Results indicate that most of the overall structural properties were preserved throughout a significant proportion of the ultimate fracture load. For the cases studied, changes in structural behavior began to occur after 70 percent of the ultimate fracture load was applied. However, the individual nature of the structural change was rather varied depending on the laminate configuration, fiber orientation, and the boundary conditions.

  11. Creep rupture behavior of unidirectional advanced composites

    NASA Technical Reports Server (NTRS)

    Yeow, Y. T.

    1980-01-01

    A 'material modeling' methodology for predicting the creep rupture behavior of unidirectional advanced composites is proposed. In this approach the parameters (obtained from short-term tests) required to make the predictions are the three principal creep compliance master curves and their corresponding quasi-static strengths tested at room temperature (22 C). Using these parameters in conjunction with a failure criterion, creep rupture envelopes can be generated for any combination of in-plane loading conditions and ambient temperature. The analysis was validated experimentally for one composite system, the T300/934 graphite-epoxy system. This was done by performing short-term creep tests (to generate the principal creep compliance master curves with the time-temperature superposition principle) and relatively long-term creep rupture tensile tests of off-axis specimens at 180 C. Good to reasonable agreement between experimental and analytical results is observed.

  12. Compressive behavior of unidirectional fibrous composites

    NASA Technical Reports Server (NTRS)

    Sinclair, J. H.; Chamis, C. C.

    1983-01-01

    The longitudinal compressive behavior of unidirectional fiber composites was investigated by using the Illinois Institute of Technology Research Institute (IITRI) test method with thick and thin test specimens. The test data obtained are interpreted by means of stress/strain curves from back-to-back strain gages, examination of fracture surfaces by scanning electron microscope, and predictive equations for distinct failure modes including fiber compression failure. Euler buckling, delamination, and flexure. The results show that longitudinal compressive fracture is induced by a combination of delamination, flexure, and fiber tier breaks. No distinct fracture surface characteristics can be associated with unique failure modes. An equation is described that can be used to extract the longitudinal compressive strength from the longitudinal tensile and flexural strengths of the same composite system.

  13. Fetal antiepileptic drug exposure: Adaptive and emotional/behavioral functioning at age 6years.

    PubMed

    Cohen, Morris J; Meador, Kimford J; Browning, Nancy; May, Ryan; Baker, Gus A; Clayton-Smith, Jill; Kalayjian, Laura A; Kanner, Andres; Liporace, Joyce D; Pennell, Page B; Privitera, Michael; Loring, David W

    2013-11-01

    The Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study is a prospective observational multicenter study in the USA and UK, which enrolled pregnant women with epilepsy on antiepileptic drug (AED) monotherapy from 1999 to 2004. The study aimed to determine if differential long-term neurodevelopmental effects exist across four commonly used AEDs (carbamazepine, lamotrigine, phenytoin, and valproate). In this report, we examine fetal AED exposure effects on adaptive and emotional/behavioral functioning at 6years of age in 195 children (including three sets of twins) whose parent (in most cases, the mother) completed at least one of the rating scales. Adjusted mean scores for the four AED groups were in the low average to average range for parent ratings of adaptive functioning on the Adaptive Behavior Assessment System-Second Edition (ABAS-II) and for parent and teacher ratings of emotional/behavioral functioning on the Behavior Assessment System for Children (BASC). However, children whose mothers took valproate during pregnancy had significantly lower General Adaptive Composite scores than the lamotrigine and phenytoin groups. Further, a significant dose-related performance decline in parental ratings of adaptive functioning was seen for both valproate and phenytoin. Children whose mothers took valproate were also rated by their parents as exhibiting significantly more atypical behaviors and inattention than those in the lamotrigine and phenytoin groups. Based upon BASC parent and teacher ratings of attention span and hyperactivity, children of mothers who took valproate during their pregnancy were at a significantly greater risk for a diagnosis of ADHD. The increased likelihood of difficulty with adaptive functioning and ADHD with fetal valproate exposure should be communicated to women with epilepsy who require antiepileptic medication. Finally, additional research is needed to confirm these findings in larger prospective study samples, examine

  14. Nutrients affecting brain composition and behavior

    NASA Technical Reports Server (NTRS)

    Wurtman, R. J.

    1987-01-01

    This review examines the changes in brain composition and in various brain functions, including behavior, that can follow the ingestion of particular foods or nutrients. It details those that are best understood: the increases in serotonin, catecholamine, or acetylcholine synthesis that can occur subsequent to food-induced increases in brain levels of tryptophan, tyrosine, or choline; it also discusses the various processes that must intervene between the mouth and the synapse, so to speak, in order for a nutrient to affect neurotransmission, and it speculates as to additional brain chemicals that may ultimately be found to be affected by changes in the availability of their nutrient precursors. Because the brain chemicals best known to be nutrient dependent overlap with those thought to underlie the actions of most of the drugs used to treat psychiatric diseases, knowledge of this dependence may help the psychiatrist to understand some of the pathologic processes occurring in his/her patients, particularly those with appetitive symptoms. At the very least, such knowledge should provide the psychiatrist with objective criteria for judging when to take seriously assertions that particular foods or nutrients do indeed affect behavior (e.g., in hyperactive children). If the food can be shown to alter neurotransmitter release, it may be behaviorally-active; however, if it lacks a discernible neurochemical effect, the likelihood that it really alters behavior is small.

  15. Information theory of adaptation in neurons, behavior, and mood

    PubMed Central

    Sharpee, Tatyana O.; Calhoun, Adam J.; Chalasani, Sreekanth H.

    2014-01-01

    The ability to make accurate predictions of future stimuli and consequences of one’s actions are crucial for the survival and appropriate decision-making. These predictions are constantly being made at different levels of the nervous system. This is evidenced by adaptation to stimulus parameters in sensory coding, and in learning of an up-to-date model of the environment at the behavioral level. This review will discuss recent findings that actions of neurons and animals are selected based on detailed stimulus history in such a way as to maximize information for achieving the task at hand. Information maximization dictates not only how sensory coding should adapt to various statistical aspects of stimuli, but also that reward function should adapt to match the predictive information from past to future. PMID:24709600

  16. Mechanical behavior of carbon-carbon composites

    NASA Technical Reports Server (NTRS)

    Rozak, G. A.

    1984-01-01

    A general background, test plan, and some results of preliminary examinations of a carbon-carbon composite material are presented with emphasis on mechanical testing and inspection techniques. Experience with testing and evaluation was gained through tests of a low modulus carbon-carbon material, K-Karb C. The properties examined are the density - 1.55 g/cc; four point flexure strength in the warp - 137 MPa (19,800 psi) and the fill - 95.1 MPa (13,800 psi,) directions; and the warp interlaminar shear strength - 14.5 MPa (2100 psi). Radiographic evaluation revealed thickness variations and the thinner areas of the composite were scrapped. The ultrasonic C-scan showed attenuation variations, but these did not correspond to any of the physical and mechanical properties measured. Based on these initial tests and a survey of the literature, a plan has been devised to examine the effect of stress on the oxidation behavior, and the strength degradation of coated carbon-carbon composites. This plan will focus on static fatigue tests in the four point flexure mode in an elevated temperature, oxidizing environment.

  17. High strain rate behavior of polyurea compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant S.; Milby, Christopher

    2012-03-01

    High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to strain rates of over 6000/s. High strain rate results from these tests have shown varying trends as a function of increasing strain. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower strain. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of strain hardening characteristics as the material is compressed to 50% strain, compared to 1000 molecular weight amine based material.

  18. Geometry adaptive control of a composite reflector using PZT actuator

    NASA Astrophysics Data System (ADS)

    Lan, Lan; Jiang, Shuidong; Zhou, Yang; Fang, Houfei; Tan, Shujun; Wu, Zhigang

    2015-04-01

    Maintaining geometrical high precision for a graphite fiber reinforced composite (GFRC) reflector is a challenging task. Although great efforts have been placed to improve the fabrication precision, geometry adaptive control for a reflector is becoming more and more necessary. This paper studied geometry adaptive control for a GFRC reflector with piezoelectric ceramic transducer (PZT) actuators assembled on the ribs. In order to model the piezoelectric effect in finite element analysis (FEA), a thermal analogy was used in which the temperature was applied to simulate the actuation voltage, and the piezoelectric constant was mimicked by a Coefficient of Thermal Expansion (CTE). PZT actuator's equivalent model was validated by an experiment. The deformations of a triangular GFRC specimen with three PZT actuators were also measured experimentally and compared with that of simulation. This study developed a multidisciplinary analytical model, which includes the composite structure, thermal, thermal deformation and control system, to perform an optimization analysis and design for the adaptive GFRC reflector by considering the free vibration, gravity deformation and geometry controllability.

  19. Biologically-inspired adaptive obstacle negotiation behavior of hexapod robots.

    PubMed

    Goldschmidt, Dennis; Wörgötter, Florentin; Manoonpong, Poramate

    2014-01-01

    Neurobiological studies have shown that insects are able to adapt leg movements and posture for obstacle negotiation in changing environments. Moreover, the distance to an obstacle where an insect begins to climb is found to be a major parameter for successful obstacle negotiation. Inspired by these findings, we present an adaptive neural control mechanism for obstacle negotiation behavior in hexapod robots. It combines locomotion control, backbone joint control, local leg reflexes, and neural learning. While the first three components generate locomotion including walking and climbing, the neural learning mechanism allows the robot to adapt its behavior for obstacle negotiation with respect to changing conditions, e.g., variable obstacle heights and different walking gaits. By successfully learning the association of an early, predictive signal (conditioned stimulus, CS) and a late, reflex signal (unconditioned stimulus, UCS), both provided by ultrasonic sensors at the front of the robot, the robot can autonomously find an appropriate distance from an obstacle to initiate climbing. The adaptive neural control was developed and tested first on a physical robot simulation, and was then successfully transferred to a real hexapod robot, called AMOS II. The results show that the robot can efficiently negotiate obstacles with a height up to 85% of the robot's leg length in simulation and 75% in a real environment. PMID:24523694

  20. Biologically-inspired adaptive obstacle negotiation behavior of hexapod robots

    PubMed Central

    Goldschmidt, Dennis; Wörgötter, Florentin; Manoonpong, Poramate

    2014-01-01

    Neurobiological studies have shown that insects are able to adapt leg movements and posture for obstacle negotiation in changing environments. Moreover, the distance to an obstacle where an insect begins to climb is found to be a major parameter for successful obstacle negotiation. Inspired by these findings, we present an adaptive neural control mechanism for obstacle negotiation behavior in hexapod robots. It combines locomotion control, backbone joint control, local leg reflexes, and neural learning. While the first three components generate locomotion including walking and climbing, the neural learning mechanism allows the robot to adapt its behavior for obstacle negotiation with respect to changing conditions, e.g., variable obstacle heights and different walking gaits. By successfully learning the association of an early, predictive signal (conditioned stimulus, CS) and a late, reflex signal (unconditioned stimulus, UCS), both provided by ultrasonic sensors at the front of the robot, the robot can autonomously find an appropriate distance from an obstacle to initiate climbing. The adaptive neural control was developed and tested first on a physical robot simulation, and was then successfully transferred to a real hexapod robot, called AMOS II. The results show that the robot can efficiently negotiate obstacles with a height up to 85% of the robot's leg length in simulation and 75% in a real environment. PMID:24523694

  1. Behavioral training promotes multiple adaptive processes following acute hearing loss

    PubMed Central

    Keating, Peter; Rosenior-Patten, Onayomi; Dahmen, Johannes C; Bell, Olivia; King, Andrew J

    2016-01-01

    The brain possesses a remarkable capacity to compensate for changes in inputs resulting from a range of sensory impairments. Developmental studies of sound localization have shown that adaptation to asymmetric hearing loss can be achieved either by reinterpreting altered spatial cues or by relying more on those cues that remain intact. Adaptation to monaural deprivation in adulthood is also possible, but appears to lack such flexibility. Here we show, however, that appropriate behavioral training enables monaurally-deprived adult humans to exploit both of these adaptive processes. Moreover, cortical recordings in ferrets reared with asymmetric hearing loss suggest that these forms of plasticity have distinct neural substrates. An ability to adapt to asymmetric hearing loss using multiple adaptive processes is therefore shared by different species and may persist throughout the lifespan. This highlights the fundamental flexibility of neural systems, and may also point toward novel therapeutic strategies for treating sensory disorders. DOI: http://dx.doi.org/10.7554/eLife.12264.001 PMID:27008181

  2. On fractional order composite model reference adaptive control

    NASA Astrophysics Data System (ADS)

    Wei, Yiheng; Sun, Zhenyuan; Hu, Yangsheng; Wang, Yong

    2016-08-01

    This paper presents a novel composite model reference adaptive control approach for a class of fractional order linear systems with unknown constant parameters. The method is extended from the model reference adaptive control. The parameter estimation error of our method depends on both the tracking error and the prediction error, whereas the existing method only depends on the tracking error, which makes our method has better transient performance in the sense of generating smooth system output. By the aid of the continuous frequency distributed model, stability of the proposed approach is established in the Lyapunov sense. Furthermore, the convergence property of the model parameters estimation is presented, on the premise that the closed-loop control system is stable. Finally, numerical simulation examples are given to demonstrate the effectiveness of the proposed schemes.

  3. Adaptive and Maladaptive Behavior in Children with Smith-Magenis Syndrome

    ERIC Educational Resources Information Center

    Martin, Staci C.; Wolters, Pamela L.; Smith, Ann C. M.

    2006-01-01

    Children with Smith-Magenis Syndrome (SMS) exhibit deficits in adaptive behavior but systematic studies using objective measures are lacking. This descriptive study assessed adaptive functioning in 19 children with SMS using the Vineland Adaptive Behavior Scales (VABS). Maladaptive behavior was examined through parent questionnaires and the…

  4. Vineland Adaptive Behavior Profiles in Children with Autism and Moderate to Severe Developmental Delay.

    ERIC Educational Resources Information Center

    Fenton, Gemma; D'Ardia, Caterina; Valente, Donatella; Vecchio, Ilaria del; Fabrizi, Anna; Bernabei, Paola

    2003-01-01

    A study examined adaptive behavior profiles in children (ages 21-108 months) with moderate to severe developmental delay and autism (n=23) and without autism (n=27). The Vineland Adaptive Behavior Scales was administered, and contrary to initial predictions, the sample presented fairly homogeneous adaptive behavior profiles. (Contains references.)…

  5. Adaptive Behavior of Primary School Students with Visual Impairments: The Impact of Educational Settings

    ERIC Educational Resources Information Center

    Metsiou, Katerina; Papadopoulos, Konstantinos; Agaliotis, Ioannis

    2011-01-01

    This study explored the adaptive behavior of primary school students with visual impairments, as well as the impact of educational setting on their adaptive behavior. Instrumentation included an informal questionnaire and the Vineland Adaptive Behavior Scales. Participants were 36 primary school students with visual impairments. The educational…

  6. Site-specific group selection drives locally adapted group compositions.

    PubMed

    Pruitt, Jonathan N; Goodnight, Charles J

    2014-10-16

    Group selection may be defined as selection caused by the differential extinction or proliferation of groups. The socially polymorphic spider Anelosimus studiosus exhibits a behavioural polymorphism in which females exhibit either a 'docile' or 'aggressive' behavioural phenotype. Natural colonies are composed of a mixture of related docile and aggressive individuals, and populations differ in colonies' characteristic docile:aggressive ratios. Using experimentally constructed colonies of known composition, here we demonstrate that population-level divergence in docile:aggressive ratios is driven by site-specific selection at the group level--certain ratios yield high survivorship at some sites but not others. Our data also indicate that colonies responded to the risk of extinction: perturbed colonies tended to adjust their composition over two generations to match the ratio characteristic of their native site, thus promoting their long-term survival in their natal habitat. However, colonies of displaced individuals continued to shift their compositions towards mixtures that would have promoted their survival had they remained at their home sites, regardless of their contemporary environment. Thus, the regulatory mechanisms that colonies use to adjust their composition appear to be locally adapted. Our data provide experimental evidence of group selection driving collective traits in wild populations. PMID:25274310

  7. The emerging roles of melanopsin in behavioral adaptation to light

    PubMed Central

    Hatori, Megumi; Panda, Satchidananda

    2010-01-01

    Adaptation of behavior and physiology to changes in the ambient light level is of critical importance to life. These adaptations include light modulation of neuroendocrine function and temporal alignment of physiology and behavior to the day:night cycle by the circadian clock. These non-image forming (NIF) responses can function independent of rod and cone photoreceptors but depend on ocular light reception, suggesting the participation of novel photoreceptors in the eye. The discovery of melanopsin in intrinsically photosensitive retinal ganglion cells (ipRGCs) and genetic proof for its important role in major NIF responses have offered an exciting entry point to comprehend how mammals adapt to the light environment. Here, we review the recent advances in our understanding of the emerging roles of melanopsin and of ipRGCs. These findings now offer new avenues to understand the role of ambient light in sleep, alertness, dependent physiologies and potential pharmacological intervention as well as lifestyle modifications to improve the quality of life. PMID:20810319

  8. Compression behavior of delaminated composite plates

    NASA Technical Reports Server (NTRS)

    Peck, Scott O.; Springer, George S.

    1989-01-01

    The response of delaminated composite plates to compressive in-plane loads was investigated. The delaminated region may be either circular or elliptical, and may be located between any two plies of the laminate. For elliptical delaminations, the axes of the ellipse may be arbitrarily oriented with respect to the applied loads. A model was developed that describes the stresses, strains, and deformation of the sublaminate created by the delamination. The mathematical model is based on a two dimensional nonlinear plate theory that includes the effects of transverse shear deformation. The model takes into account thermal and moisture induced strains, transverse pressures acting on the sublaminate, and contact between the sublaminate and plate. The solution technique used is the Ritz method. A computationally efficient computer implementation of the model was developed. The code can be used to predict the nonlinear-load-strain behavior of the sublaminate including the buckling load, postbuckling behavior, and the onset of delamination growth. The accuracy of the code was evaluated by comparing the model results to benchmark analytical solutions. A series of experiments was conducted on Fiberite T300/976 graphite/epoxy laminates bonded to an aluminum honeycomb core forming a sandwich panel. Either circles or ellipses made from Teflon film were embedded in the laminates, simulating the presence of a delamination. Each specimen was loaded in compression and the strain history of the sublaminate was recorded far into the postbuckling regime. The extent of delamination growth was evaluated by C-scan examination of each specimen. The experimental data were compared to code predictions. The code was found to describe the data with reasonable accuracy. A sensitivity study examined the relative importance of various material properties, the delamination dimensions, the contact model, the transverse pressure differential, the critical strain energy release rate, and the relative

  9. The Evaluation of Various Restoration Techniques on Internal Adaptation of Composites in Class V Cavities

    PubMed Central

    Dionysopoulos, D.; Papadopoulos, C.; Koliniotou-Koumpia, E.

    2014-01-01

    Aim. The aim of this study was to evaluate the effect of different restoration techniques on the formation of internal microgaps between materials and dentin in class V restorations. Materials and Methods. Twenty-five extracted human premolars were prepared with standardized class V cavity outlines (3 mm × 2 mm × 2 mm). The cavities were randomly divided into 5 groups of 10 cavities each and restored according to manufacturer's instructions: Group 1: preheating (55°C) conventional composite (Filtek Z250), Group 2: flowable composite (Filtek Flow), Group 3: Filtek Flow + Filtek Z250 light-cured separately, Group 4: Filtek Flow + Filtek Z250 light-cured simultaneously, and Group 5 (control): Filtek Z250 at room temperature (23°C). The specimens were then thermocycled and cross-sectioned through the center of the restoration. Subsequently, impressions were taken, and epoxy resin replicas were made. The internal adaptation of the materials to the axial wall was analyzed under SEM. Results. The preheated Filtek Z250 (Group 1) showed better internal adaptation than the room temperature groups (P < 0.05). The combination of Filtek Flow with Filtek Z250 which was light-cured separately (Group 3) exhibited better internal adaptation than control group (P < 0.05). Conclusion. Different restoration techniques exhibit different behavior regarding internal adaptation to dentin after photopolymerization. PMID:25349611

  10. Development vs. behavior: a role for neural adaptation in evolution?

    PubMed

    Ghysen, Alain; Dambly-Chaudière, Christine

    2016-01-01

    We examine the evolution of sensory organ patterning in the lateral line system of fish. Based on recent studies of how this system develops in zebrafish, and on comparative analyses between zebrafish and tuna, we argue that the evolution of lateral line patterns is mostly determined by variations in the underlying developmental processes, independent of any selective pressure. Yet the development of major developmental innovations is so directly linked to their exploitation that it is hard not to think of them as selected for, i.e., adaptive. We propose that adaptation resides mostly in how the nervous system adjusts to new morphologies to make them functional, i.e., that species are neurally adapted to whatever morphology is provided to them by their own developmental program. We show that recent data on behavioral differences between cave forms (blind) and surface forms (eyed) of the mexican fish Astyanax fasciatus support this view, and we propose that this species might provide a unique opportunity to assess the nature of adaptation and of selection in animal evolution. PMID:27389980

  11. Solid-Liquid Self-Adaptive Polymeric Composite.

    PubMed

    Dong, Pei; Chipara, Alin Cristian; Loya, Phillip; Yang, Yingchao; Ge, Liehui; Lei, Sidong; Li, Bo; Brunetto, Gustavo; Machado, Leonardo D; Hong, Liang; Wang, Qizhong; Yang, Bilan; Guo, Hua; Ringe, Emilie; Galvao, Douglas S; Vajtai, Robert; Chipara, Mircea; Tang, Ming; Lou, Jun; Ajayan, Pulickel M

    2016-01-27

    A solid-liquid self-adaptive composite (SAC) is synthesized using a simple mixing-evaporation protocol, with poly(dimethylsiloxane) (PDMS) and poly(vinylidene fluoride) (PVDF) as active constituents. SAC exists as a porous solid containing a near equivalent distribution of the solid (PVDF)-liquid (PDMS) phases, with the liquid encapsulated and stabilized within a continuous solid network percolating throughout the structure. The pores, liquid, and solid phases form a complex hierarchical structure, which offers both mechanical robustness and a significant structural adaptability under external forces. SAC exhibits attractive self-healing properties during tension, and demonstrates reversible self-stiffening properties under compression with a maximum of 7-fold increase seen in the storage modulus. In a comparison to existing self-healing and self-stiffening materials, SAC offers distinct advantages in the ease of fabrication, high achievable storage modulus, and reversibility. Such materials could provide a new class of adaptive materials system with multifunctionality, tunability, and scale-up potentials. PMID:26720058

  12. Industry Cluster's Adaptive Co-competition Behavior Modeling Inspired by Swarm Intelligence

    NASA Astrophysics Data System (ADS)

    Xiang, Wei; Ye, Feifan

    Adaptation helps the individual enterprise to adjust its behavior to uncertainties in environment and hence determines a healthy growth of both the individuals and the whole industry cluster as well. This paper is focused on the study on co-competition adaptation behavior of industry cluster, which is inspired by swarm intelligence mechanisms. By referencing to ant cooperative transportation and ant foraging behavior and their related swarm intelligence approaches, the cooperative adaptation and competitive adaptation behavior are studied and relevant models are proposed. Those adaptive co-competition behaviors model can be integrated to the multi-agent system of industry cluster to make the industry cluster model more realistic.

  13. Adaptive Vocal Behavior Drives Perception by Echolocation in Bats

    PubMed Central

    Moss, Cynthia F.; Chiu, Chen; Surlykke, Annemarie

    2011-01-01

    Echolocation operates through adaptive sensorimotor systems that collectively enable the bat to localize and track sonar objects as it flies. The features of sonar signals used by a bat to probe its surroundings determine the information available to its acoustic imaging system. In turn, the bat’s perception of a complex scene guides its active adjustments in the features of subsequent sonar vocalizations. Here, we propose that the bat’s active vocal-motor behaviors play directly into its representation of a dynamic auditory scene. PMID:21705213

  14. Chaotic Patterns in Lotka-Volterra Systems with Behavioral Adaptation

    NASA Astrophysics Data System (ADS)

    Lacitignola, D.; Tebaldi, C.

    2006-03-01

    We study the properties of a n2-dimensional Lotka-Volterra system describing competition among species with behaviorally adaptive abilities, in which one species is made ecologically differentiated with respect to the others by carrying capacity and intrinsic growth rate. The case in which one species has a carrying capacity higher than the others is considered here. Stability of equilibria and time-dependent regimes have been investigated in the case of four species: an interesting example of chaotic window and period-adding sequences is presented and discussed.

  15. Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels

    NASA Astrophysics Data System (ADS)

    Paine, Jeffrey S.; Rogers, Craig A.

    1995-05-01

    Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R/h < 15) vessels are required. For efficient material use in composite material vessels, the radial dilation (expansion or swelling) of the composite vessel can often approach values nearing 2 percent of the diameter. Over long periods of internal pressure loading over elevated temperatures, composite material cylinders may also experience substantial creep. The short term dilation and long term creep are not problematic for applications requiring only the containment of the pressurized fluid. In applications where metallic liners are required, however, substantial dilation and creep causes plastic yielding which leads to reduced fatigue life. To applications such as a hydraulic accumulator, where a piston is employed to fit and seal the fluid in the composite cylinder, the dilation and creep may allow leakage and pressure loss around the piston. A concept called the adaptive composite cylinder is experimentally presented. Shape memory alloy wire in epoxy resin is wrapped around or within polymer matrix composite cylinders to reduce radial dilation of the cylinder. Experimental results are presented that demonstrate the ability of the SMA wire layers to reduce radial dilation. Results from experimental testing of the recovery stress fatigue response of nitinol shape memory alloy wires is also presented.

  16. Behavior of an adaptive bio-inspired spider web

    NASA Astrophysics Data System (ADS)

    Zheng, Lingyue; Behrooz, Majid; Huie, Andrew; Hartman, Alex; Gordaninejad, Faramarz

    2015-03-01

    The goal of this study is to demonstrate the feasibility of an artificial adaptive spider web with comparable behavior to a real spider web. First, the natural frequency and energy absorption ability of a passive web is studied. Next, a control system that consists of stepper motors, load cells and an Arduino, is constructed to mimic a spider's ability to control the tension of radial strings in the web. The energy related characteristics in the artificial spider web is examined while the pre-tension of the radial strings are varied. Various mechanical properties of a damaged spider web are adjusted to study their effect on the behavior of the web. It is demonstrated that the pre-tension and stiffness of the web's radial strings can significantly affect the natural frequency and the total energy of the full and damaged webs.

  17. Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function.

    PubMed

    Pugliese, Cara E; Anthony, Laura Gutermuth; Strang, John F; Dudley, Katerina; Wallace, Gregory L; Naiman, Daniel Q; Kenworthy, Lauren

    2016-02-01

    This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates for their developmental stage, adaptive behavior in most participants was impaired and did not improve over time. Prior EF predicted later adaptive behavior in daily living skills and socialization domains after controlling for age and IQ. Self-monitoring behaviors robustly predicted later adaptive behavior in all domains (d = 0.60-0.94). Results support targeting treatment of adaptive skills in ASD, as well as the importance of assessing for EF problems that may contribute to adaptive behavior difficulties. PMID:26349921

  18. The Pupillary Orienting Response Predicts Adaptive Behavioral Adjustment after Errors

    PubMed Central

    Murphy, Peter R.; van Moort, Marianne L.; Nieuwenhuis, Sander

    2016-01-01

    Reaction time (RT) is commonly observed to slow down after an error. This post-error slowing (PES) has been thought to arise from the strategic adoption of a more cautious response mode following deployment of cognitive control. Recently, an alternative account has suggested that PES results from interference due to an error-evoked orienting response. We investigated whether error-related orienting may in fact be a pre-cursor to adaptive post-error behavioral adjustment when the orienting response resolves before subsequent trial onset. We measured pupil dilation, a prototypical measure of autonomic orienting, during performance of a choice RT task with long inter-stimulus intervals, and found that the trial-by-trial magnitude of the error-evoked pupil response positively predicted both PES magnitude and the likelihood that the following response would be correct. These combined findings suggest that the magnitude of the error-related orienting response predicts an adaptive change of response strategy following errors, and thereby promote a reconciliation of the orienting and adaptive control accounts of PES. PMID:27010472

  19. Semi-solid state adaptive impedance composites for HIRF protection

    NASA Astrophysics Data System (ADS)

    Bramlette, Richard B.; Barrett, Ronald M.

    2010-04-01

    The feasibility of piezoelectric-based Adaptive-Impedance Composites (AIC) as a method of protecting aircraft equipment from lightning strike events and the resultant High-Intensity Radiated Fields (HIRF) was investigated. Classical Laminated Plate Theory (CLPT) and sheet vibration theory were applied to analytically derive the performance of the AIC. Multiple prototypes were built for high voltage testing which revealed closed- to open-circuit switching as fast as 77 μs. It was observed that slight geometric variations of the AIC strongly influenced the activation voltage. The voltage necessary to trigger the 85mm long, 3rd generation AIC's impedance could be set between 10 and 60 V. The test data and the analytical predictions were compared with the lightning strike data gathered by ONERA. The comparison indicated the AIC switching speed was over 30 times faster than the necessary minimum to shield typical avionics and flight control mechanisms from lightning-strike induced electrical eddy currents and HIRF.

  20. Personality traits, future time perspective and adaptive behavior in adolescence.

    PubMed

    Gomes Carvalho, Renato Gil; Novo, Rosa Ferreira

    2015-01-01

    Several studies provide evidence of the importance of future time perspective (FTP) for individual success. However, little research addresses the relationship between FTP and personality traits, particularly if FTP can mediate their influence on behavior. In this study we analyze the mediating of FTP in the influence of personality traits on the way adolescents live their life at school. Sample consisted in 351 students, aged from 14 to 18 years-old, at different schooling levels. Instruments were the Portuguese version of the MMPI-A, particularly the PSY-5 dimensions (Aggressiveness, Psychoticism, Disconstraint, Neuroticism, Introversion), a FTP questionnaire, and a survey on school life, involving several indicators of achievement, social integration, and overall satisfaction. With the exception of Neuroticism, the results show significant mediation effects (p < .001) of FTP on most relationships between PSY-5 dimensions and school life variables. Concerning Disconstraint, FTP mediated its influence on overall satisfaction (β = -.125) and school achievement (β = -.106). In the case of Introversion, significant mediation effects occurred for interpersonal difficulties (β = .099) and participation in extracurricular activities (β = -.085). FTP was also a mediator of Psychoticism influence in overall satisfaction (β = -.094), interpersonal difficulties (β = .057), and behavior problems (β = .037). Finally, FTP mediated the influence of Aggressiveness on overall satisfaction (β = -.061), interpersonal difficulties (β = .040), achievement (β = -.052), and behavior problems (β = .023). Results are discussed considering the importance of FTP in the impact of some personality structural characteristics in students' school adaptation. PMID:25907852

  1. Unified approach for predicting mechanical behaviors of textile composites

    SciTech Connect

    Hamada, H.; Fujita, A.; Maekawa, Z.; Yokoyama, A.

    1994-12-31

    The purpose of this study was to establish unified prediction method of mechanical properties and fracture behaviors in the composites reinforced with textile fabric preforms such as two and three-dimensional woven fabrics, braided fabrics and knitted fabrics. In this analysis model, factors deciding weaving structure such as fiber orientation state, crimp and continuity of fiber, transmission of force at cross part between fiber bundles and surface resin of the composite which affect on the mechanical properties and fracture behavior of the textile composites, were considered. The validity of this numerical analysis method was examined by comparing predicted results with experimental data. Consequently, it could be confirmed that this numerical analysis method was valid for predicting the mechanical properties and fracture behavior of the textile composites. In this analysis model, not only the mechanical properties but also local stress state and fracture behavior of the textile composites could be estimated.

  2. Low Temperature Adaptation Is Not the Opposite Process of High Temperature Adaptation in Terms of Changes in Amino Acid Composition

    PubMed Central

    Yang, Ling-Ling; Tang, Shu-Kun; Huang, Ying; Zhi, Xiao-Yang

    2015-01-01

    Previous studies focused on psychrophilic adaptation generally have demonstrated that multiple mechanisms work together to increase protein flexibility and activity, as well as to decrease the thermostability of proteins. However, the relationship between high and low temperature adaptations remains unclear. To investigate this issue, we collected the available predicted whole proteome sequences of species with different optimal growth temperatures, and analyzed amino acid variations and substitutional asymmetry in pairs of homologous proteins from related species. We found that changes in amino acid composition associated with low temperature adaptation did not exhibit a coherent opposite trend when compared with changes in amino acid composition associated with high temperature adaptation. This result indicates that during their evolutionary histories the proteome-scale evolutionary patterns associated with prokaryotes exposed to low temperature environments were distinct from the proteome-scale evolutionary patterns associated with prokaryotes exposed to high temperature environments in terms of changes in amino acid composition of the proteins. PMID:26614525

  3. Learning about stress: neural, endocrine and behavioral adaptations.

    PubMed

    McCarty, Richard

    2016-09-01

    In this review, nonassociative learning is advanced as an organizing principle to draw together findings from both sympathetic-adrenal medullary and hypothalamic-pituitary-adrenocortical (HPA) axis responses to chronic intermittent exposure to a variety of stressors. Studies of habituation, facilitation and sensitization of stress effector systems are reviewed and linked to an animal's prior experience with a given stressor, the intensity of the stressor and the appraisal by the animal of its ability to mobilize physiological systems to adapt to the stressor. Brain pathways that regulate physiological and behavioral responses to stress are discussed, especially in light of their regulation of nonassociative processes in chronic intermittent stress. These findings may have special relevance to various psychiatric diseases, including depression and post-traumatic stress disorder (PTSD). PMID:27294884

  4. [Adaptive behaviors to HIV risk of transmission in different populations].

    PubMed

    Grémy, I

    2005-05-01

    Since the beginning of the HIV epidemic in France, surveys aimed at better understanding risk perceptions of HIV infection and preventive sexual behaviors have been implemented in the general population, and in populations such as IVDU and homosexual men, more concerned by risks of HIV transmission. The objective of this article is to describe these surveys, to present their main results and to assess what has been the overall impact of prevention campaigns on the adoption of preventive sexual behaviors in these populations. The results show that very early after the beginning of the AIDS epidemic, both general and homosexual populations have adopted preventive sexual behaviors, mainly increasing condom use and implementing other preventive strategies. However, with the introduction of HAART in 1996, a slackening of these preventive behaviors is noted. The use of condom is less frequent, especially in the youngest generations of both general and homosexual populations. On the opposite, among IVDU, the use of sterile syringes increased dramatically as soon as over-the-counter sales of syringes was authorized in 1987, as well as the adoption of ways other than intravenous to take drugs. Both have contributed to almost stop the HIV epidemic in this specific group. The results of these surveys show that the benefits of prevention campaigns are different between populations and are reversible. It is necessary to renew the messages, campaigns and programs of prevention with the renewal of generations. It is also necessary to adapt these messages to the new scientific data, and to the evolution of social and individual representations of the disease. PMID:15878250

  5. Coordination Pattern Adaptability: Energy Cost of Degenerate Behaviors

    PubMed Central

    Seifert, Ludovic; Komar, John; Crettenand, Florent; Millet, Grégoire

    2014-01-01

    This study investigated behavioral adaptability, which could be defined as a blend between stability and flexibility of the limbs movement and their inter-limb coordination, when individuals received informational constraints. Seven expert breaststroke swimmers performed three 200-m in breaststroke at constant submaximal intensity. Each trial was performed randomly in a different coordination pattern: ‘freely-chosen’, ‘maximal glide’ and ‘minimal glide’. Two underwater and four aerial cameras enabled 3D movement analysis in order to assess elbow and knee angles, elbow-knee pair coordination, intra-cyclic velocity variations of the center of mass, stroke rate and stroke length and inter-limb coordination. The energy cost of locomotion was calculated from gas exchanges and blood lactate concentration. The results showed significantly higher glide, intra-cyclic velocity variations and energy cost under ‘maximal glide’ compared to ‘freely-chosen’ instructional conditions, as well as higher reorganization of limb movement and inter-limb coordination (p<0.05). In the ‘minimal glide’ condition, the swimmers did not show significantly shorter glide and lower energy cost, but they exhibited significantly lower deceleration of the center of mass, as well as modified limb movement and inter-limb coordination (p<0.05). These results highlight that a variety of structural adaptations can functionally satisfy the task-goal. PMID:25255016

  6. The Glenwood Assessment of Behavior of the Mentally Retarded: A Well-Factored Scale of Adaptive Behavior.

    ERIC Educational Resources Information Center

    Larsen, Gary Y.

    The paper describes the reasons for developing a new instrument to measure adaptive behavior of mentally retarded residents at Glenwood State Hospital-School and recounts the processes involved in constructing the new scale. Among complaints about the American Association on Mental Deficiency Adaptive Behavior Scale (ABS) are its inappropriateness…

  7. Telescoping Mechanics: A New Paradigm for Composite Behavior Simulation

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Gotsis, P. K.; Mital. S. K.

    2004-01-01

    This report reviews the application of telescoping mechanics to composites using recursive laminate theory. The elemental scale is the fiber-matrix slice, the behavior of which propagates to laminate. The results from using applications for typical, hybrid, and smart composites and composite-enhanced reinforced concrete structures illustrate the versatility and generality of telescoping scale mechanics. Comparisons with approximate, single-cell, and two- and three-dimensional finite-element methods demonstrate the accuracy and computational effectiveness of telescoping scale mechanics for predicting complex composite behavior.

  8. Unified Viscoplastic Behavior of Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.; Robinson, D. N.; Bartolotta, P. A.

    1992-01-01

    The need for unified constitutive models was recognized more than a decade ago in the results of phenomenological tests on monolithic metals that exhibited strong creep-plasticity interaction. Recently, metallic alloys have been combined to form high-temperature ductile/ductile composite materials, raising the natural question of whether these metallic composites exhibit the same phenomenological features as their monolithic constituents. This question is addressed in the context of a limited, yet definite (to illustrate creep/plasticity interaction) set of experimental data on the model metal matrix composite (MMC) system W/Kanthal. Furthermore, it is demonstrated that a unified viscoplastic representation, extended for unidirectional composites and correlated to W/Kanthal, can accurately predict the observed longitudinal composite creep/plasticity interaction response and strain rate dependency. Finally, the predicted influence of fiber orientation on the creep response of W/Kanthal is illustrated.

  9. Light intensity adaptation and phycobilisome composition of Microcystis aeruginosa

    SciTech Connect

    Raps, S.; Kycia, J.H.; Ledbetter, M.C.; Siegelman, H.W.

    1985-12-01

    Phycobilisomes isolated from Microcystis aeruginosa grown to midlog at high light (270 microeinsteins per square meter per second) or at low light intensities (40 microeinsteins per square meter per second) were found to be identical. Electron micrographs established that they have a triangular central core apparently consisting of three allophycocyanin trimers surrounded by six rods, each composed of two hexameric phycocyanin molecules. The apparent mass of a phycobilisome obtained by gel filtration is 2.96 x 10/sup 6/ daltons. The molar ratio of the phycobiliproteins per phycobilisome is 12 phycocyanin hexamers:9 allophycocyanin trimers. The electron microscopic observations combined with the phycobilisome apparent mass and the phycobiliprotein stoichiometry data indicate that M. aeruginosa phycobilisomes are composed of a triangular central core of three stacks of three allophycocyanin trimers and six rods each containing two phycocyanin hexamers. Adaptation of M. aeruginosa to high light intensity results in a decrease in the number of phycobilisomes per cell with no alteration in phycobilisome composition or structure.

  10. Engine environmental effects on composite behavior

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Smith, G. T.

    1980-01-01

    A series of programs were conducted to investigate and develop the application of composite materials to turbojet engines. A significant part of that effort was directed to establishing the impact resistance and defect growth chracteristics of composite materials over the wide range of environmental conditions found in commercial turbojet engine operations. Both analytical and empirical efforts were involved. The experimental programs and the analytical methodology development as well as an evaluation program for the use of composite materials as fan exit guide vanes are summarized.

  11. Thermal expansion behavior of LDEF metal matrix composites

    NASA Technical Reports Server (NTRS)

    Le, Tuyen D.; Steckel, Gary L.

    1993-01-01

    The thermal expansion behavior of Long Duration Exposure Facility (LDEF) metal matrix composite materials was studied by (1) analyzing the flight data that was recorded on orbit to determine the effects of orbital time and heating/cooling rates on the performance of the composite materials, and (2) characterizing and comparing the thermal expansion behavior of post-flight LDEF and lab-control samples. The flight data revealed that structures in space are subjected to nonuniform temperature distributions, and thermal conductivity of a material is an important factor in establishing a uniform temperature distribution and avoiding thermal distortion. The flight and laboratory data showed that both Gr/Al and Gr/Mg composites were stabilized after prolonged thermal cycling on orbit. However, Gr/Al composites showed more stable thermal expansion behavior than Gr/Mg composites and offer advantages for space structures particularly where very tight thermal stability requirements in addition to high material performance must be met.

  12. Sequential composition of dynamically dexterous robot behaviors

    SciTech Connect

    Burridge, R.R.; Rizzi, A.A.; Koditschek, D.E.

    1999-06-01

    The authors report on efforts to develop a sequential robot controller-composition technique in the context of dexterous batting maneuvers. A robot with a flat paddle is required to strike repeatedly at a thrown ball until the ball is brought to rest on the paddle at a specified location. The robot`s reachable workspace is blocked by an obstacle that disconnects the free space formed when the ball and paddle remain in contact, forcing the machine to let go for a time to bring the ball to the desired state. The controller compositions the authors create guarantee that a ball introduced in the safe workspace remains there and is ultimately brought to the goal. They report on experimental results from an implementation of these formal composition methods, and present descriptive statistics characterizing the experiments.

  13. Tensile and fatigue behavior of tungsten/copper composites

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Gabb, Timothy P.; Kim, Y. S.

    1989-01-01

    Work on W/Cu unidirectional composites was initiated to study the behavior of this ductile-ductile composite system under thermomechanical fatigue and to examine the applicability of fatigue-life prediction methods for thermomechanical fatigue of this metal matrix composite. The first step was to characterize the tensile behavior of four ply, 10 vol. percent W/Cu plates at room and elevated temperatures. Fatigue tests were conducted in load control on 0 degree specimens at 260 C. The maximum cyclic stress was varied but the minimum cyclic stress was kept constant. All tests were performed in vacuum. The strain at failure increased with increasing maximum cyclic stress.

  14. Behavior and Adaptive Functioning in Adolescents with Down Syndrome: Specifying Targets for Intervention

    ERIC Educational Resources Information Center

    Jacola, Lisa M.; Hickey, Francis; Howe, Steven R.; Esbensen, Anna; Shear, Paula K.

    2014-01-01

    Adolescents with Down syndrome can demonstrate increased behavior problems as compared with typical peers. Few studies have explored whether behavior impacts adaptive functioning. Caregiver report from the Behavioral Assessment System for Children, 2nd Edition (BASC-2; Reynolds & Kamphaus, 2004) and the Child Behavioral Checklist (CBCL;…

  15. Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function

    ERIC Educational Resources Information Center

    Pugliese, Cara E.; Anthony, Laura Gutermuth; Strang, John F.; Dudley, Katerina; Wallace, Gregory L.; Naiman, Daniel Q.; Kenworthy, Lauren

    2016-01-01

    This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates…

  16. Adaptive Skills, Behavior Problems, and Parenting Stress in Mothers of Boys with Fragile X Syndrome

    ERIC Educational Resources Information Center

    Sarimski, Klaus

    2010-01-01

    The relationship of temperament, atypical behaviors, and adaptive behavior of young boys with Fragile X syndrome on mothers' parenting stress was analyzed. Twenty-six boys with Fragile X syndrome (30-88 months of age) participated. The overall development of the participants was significantly delayed with a specific profile of adaptive behaviors…

  17. Maladaptive Behaviors Related to Adaptive Decline in Aging Adults with Mental Retardation.

    ERIC Educational Resources Information Center

    Urv, Tiina K.; Zigman, Warren B.; Silverman, Wayne

    2003-01-01

    Changes in patterns of maladaptive behavior related to age-associated adaptive declines were investigated in 529 adults with mental retardation (ages 30 to 84), 202 with Down syndrome. Certain maladaptive behaviors were related to the onset of adaptive declines, (e.g., lack of boundaries). Findings suggest similarities in the course of…

  18. Profiles and Development of Adaptive Behavior in Children with Down Syndrome

    ERIC Educational Resources Information Center

    Dykens, Elisabeth; Hodapp, Robert; Evans, David

    2006-01-01

    The profiles and developmental trajectories of adaptive behavior were cross-sectionally examined in 80 children with Down syndrome ages 1 to 11.5 years using the Vineland Adaptive Behavior Scales. Profile findings indicated a significant weakness in communication relative to daily living and socialization skills. Within communication itself,…

  19. Psychopathological Manifestations of Children with Intellectual Disabilities According to Their Cognitive and Adaptive Behavior Profile

    ERIC Educational Resources Information Center

    Tremblay, Karine N.; Richer, Louis; Lachance, Lise; Cote, Alain

    2010-01-01

    Children with intellectual disabilities show deficits in cognitive abilities and adaptive behavior which increase the risk of psychopathological disorders. This exploratory study aims at delineating profiles of children based on their cognitive functioning and adaptive behaviors, and to compare them on psychopathological manifestations. A…

  20. Adaptive Behavior among Adults with Intellectual Disabilities and Its Relationship to Community Independence

    ERIC Educational Resources Information Center

    Woolf, Steve; Woolf, Christine Merman; Oakland, Thomas

    2010-01-01

    This study examined relationships between general adaptive behavior and the degree of community independence displayed by 272 adults with intellectual disabilities. Specifically, the Adaptive Behavior Assessment System-Second Edition (ABAS-II; Harrison & Oakland, 2003) was completed for each participant and compared with actual levels of work and…

  1. Variability in Adaptive Behavior in Autism: Evidence for the Importance of Family History

    ERIC Educational Resources Information Center

    Mazefsky, Carla A.; Williams, Diane L.; Minshew, Nancy J.

    2008-01-01

    Adaptive behavior in autism is highly variable and strongly related to prognosis. This study explored family history as a potential source of variability in adaptive behavior in autism. Participants included 77 individuals (mean age = 18) with average or better intellectual ability and autism. Parents completed the Family History Interview about…

  2. Aeroelastic behavior of composite rotor blades with swept tips

    NASA Astrophysics Data System (ADS)

    Yuan, Kuo-An; Friedmann, Peretz P.; Venkatesan, Comandur

    This paper presents an analytical study of the aeroelastic behavior of composite rotor blades with straight and swept tips. The blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. The nonlinear equations of motion for the finite element model are derived using Hamilton's principle and based on a moderate deflection theory and accounts for: arbitrary cross-sectional shape, pretwist, generally anisotropic material behavior, transverse shears and out-of-plane warping. Numerical results illustrating the effects of tip sweep, anhedral and composite ply orientation on blade aeroelastic behavior are presented. It is shown that composite ply orientation has a substantial effect on blade stability. At low thrust conditions, certain ply orientations can cause instability in the lag mode. The flap-torsion coupling associated with tip sweep can also induce aeroelastic instability in the blade. This instability can be removed by appropriate ply orientation in the composite construction.

  3. Wear and Friction Behavior of Metal Impregnated Microporous Carbon Composites

    NASA Technical Reports Server (NTRS)

    Goller, Gultekin; Koty, D. P.; Tewari, S. N.; Singh, M.; Tekin, A.

    1996-01-01

    Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.

  4. Rescaled temperature dependence of dielectric behavior of ferroelectric polymer composites

    NASA Astrophysics Data System (ADS)

    Dang, Zhi-Min; Wang, Lan; Wang, Hai-Yan; Nan, Ce-Wen; Xie, Dan; Yin, Yi; Tjong, S. C.

    2005-04-01

    Rescaled temperature dependence of dielectric behavior of ferroelectric polyvinylidene fluoride (PVDF) filled with electroactive ceramic particles of rocksalt-type Li and Ti codoped NiO (LTNO) was studied at wide frequency ranges. Dielectric behavior of the flexible PVDF-LTNO composites with LTNO filler at the volumetric function of 0.3 exhibits a dielectric constant value, ɛ ≈50 at broad temperature range (290-360 K), and the value is frequency independent from 103 to 106Hz. The dielectric response of the composite is almost in accordance to that of pure PVDF matrix polymer. It was found that though the dielectric constant value of the composites is high due to an introduction of the rock salt-type LTNO ceramic particles with high dielectric constant, the glass transition of the polymer and dielectric relaxation related to the wide-angle oscillation of polar groups attached to the main polymer chain determine the dielectric behavior of the composite.

  5. Aeroelastic behavior of composite rotor blades with swept tips

    NASA Technical Reports Server (NTRS)

    Yuan, Kuo-An; Friedmann, Peretz P.; Venkatesan, Comandur

    1992-01-01

    This paper presents an analytical study of the aeroelastic behavior of composite rotor blades with straight and swept tips. The blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. The nonlinear equations of motion for the finite element model are derived using Hamilton's principle and based on a moderate deflection theory and accounts for: arbitrary cross-sectional shape, pretwist, generally anisotropic material behavior, transverse shears and out-of-plane warping. Numerical results illustrating the effects of tip sweep, anhedral and composite ply orientation on blade aeroelastic behavior are presented. It is shown that composite ply orientation has a substantial effect on blade stability. At low thrust conditions, certain ply orientations can cause instability in the lag mode. The flap-torsion coupling associated with tip sweep can also induce aeroelastic instability in the blade. This instability can be removed by appropriate ply orientation in the composite construction.

  6. Probabilistic Simulation of Multi-Scale Composite Behavior

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2012-01-01

    A methodology is developed to computationally assess the non-deterministic composite response at all composite scales (from micro to structural) due to the uncertainties in the constituent (fiber and matrix) properties, in the fabrication process and in structural variables (primitive variables). The methodology is computationally efficient for simulating the probability distributions of composite behavior, such as material properties, laminate and structural responses. Bi-products of the methodology are probabilistic sensitivities of the composite primitive variables. The methodology has been implemented into the computer codes PICAN (Probabilistic Integrated Composite ANalyzer) and IPACS (Integrated Probabilistic Assessment of Composite Structures). The accuracy and efficiency of this methodology are demonstrated by simulating the uncertainties in composite typical laminates and comparing the results with the Monte Carlo simulation method. Available experimental data of composite laminate behavior at all scales fall within the scatters predicted by PICAN. Multi-scaling is extended to simulate probabilistic thermo-mechanical fatigue and to simulate the probabilistic design of a composite redome in order to illustrate its versatility. Results show that probabilistic fatigue can be simulated for different temperature amplitudes and for different cyclic stress magnitudes. Results also show that laminate configurations can be selected to increase the redome reliability by several orders of magnitude without increasing the laminate thickness--a unique feature of structural composites. The old reference denotes that nothing fundamental has been done since that time.

  7. Variability in Adaptive Behavior in Autism: Evidence for the Importance of Family History

    PubMed Central

    Mazefsky, C. A.; Williams, D. L.; Minshew, N. J.

    2008-01-01

    Adaptive behavior in autism is highly variable and strongly related to prognosis. This study explored family history as a potential source of variability in adaptive behavior in autism. Participants included 77 individuals (mean age=18) with average or better intellectual ability and autism. Parents completed the Family History Interview about the presence of broader autism phenotype symptoms and major psychiatric disorders in first degree relatives. Adaptive behavior was assessed via the Vineland Adaptive Behavior Scales (VABS). Based on family history variables, age, and intelligence quotient (IQ), 87% of participants were correctly classified as having impaired or average VABS scores. Family history of depression and shyness accounted for the most variance in VABS scores, and they had the greatest influence on VABS Socialization scores in particular. Possible underlying mechanisms include genetics, psychosocial factors, and social resources. This study provides initial evidence of the importance of family history to adaptive behavior in autism and has implications for genetics and treatment. PMID:18188537

  8. Metal matrix composite micromechanics: In-situ behavior influence on composite properties

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1989-01-01

    Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the current material model describes a time-temperature-stress dependency of the constituent properties in a material behavior space. The composite properties are synthesized from the constituent instantaneous properties by virtue of composite micromechanics and macromechanics models. The behavior of metal matrix composites depends on fabrication process variables, in situ fiber and matrix properties, bonding between the fiber and matrix, and/or the properties of an interphase between the fiber and matrix. Specifically, the influence of in situ matrix strength and the interphase degradation on the unidirectional composite stress-strain behavior is examined. These types of studies provide insight into micromechanical behavior that may be helpful in resolving discrepancies between experimentally observed composite behavior and predicted response.

  9. Do Children With Fragile X Syndrome Show Declines or Plateaus in Adaptive Behavior?

    PubMed

    Hahn, Laura J; Brady, Nancy C; Warren, Steven F; Fleming, Kandace K

    2015-09-01

    This study explores if children with fragile X syndrome (FXS) show advances, declines, or plateaus in adaptive behavior over time and the relationship of nonverbal cognitive abilities and autistic behavior on these trajectories. Parents of 55 children with FXS completed the Vineland Adaptive Behavior Scales ( Sparrow, Balla, & Cicchetti, 1984 ; Sparrow, Cicchetti, & Balla, 2005 ) between 3 and 6 times from 2 to 10 years of age. Using raw scores, results indicate that about half of the sample showed advances in adaptive behavior, whereas the other half showed declines, indicating a regression in skills. Children who were more cognitively advanced and had less autistic behaviors had higher trajectories. Understanding the developmental course of adaptive behavior in FXS has implications for educational planning and intervention, especially for those children showing declines. PMID:26322389

  10. Engaging African American Fathers in Behavioral Parent Training: To Adapt or Not Adapt

    PubMed Central

    Kohl, Patricia L.; Seay, Kristen D.

    2015-01-01

    The Positive Parenting Program, Triple P, is an evidence-based parenting program with strong empirical support that increases parenting skills and decreases child behavior problems. Few studies on Triple P include fathers or African American fathers. This study was undertaken to determine if adaptation to Triple P level 4 is necessary to ensure fit with urban African American fathers. Qualitative focus groups and interviews were conducted with African American fathers. Some received a brief overview of the program before giving feedback (series A) and others received the entire intervention (series B). Inductive thematic analysis was used to analyze transcripts and codebooks were developed through an iterative process. Series B fathers had fewer negative perceptions and a more detailed perspective. Limited exposure to an intervention may cause participants to provide inaccurate data on intervention acceptability. The fathers’ initial perceptions of interventions, regardless of accuracy, will affect recruitment and engagement and must be addressed. One strategy is to tailor program examples and language to reflect the experiences of African American fathers. PMID:26190952

  11. Nonlinear finite element modeling of dental composite polymerization behavior

    NASA Astrophysics Data System (ADS)

    Laughlin, Gayle A.

    2003-07-01

    Polymerization shrinkage has been one of the primary shortcomings preventing the use of resin composites as a universal dental restorative material. This shrinkage of the bonded restoration causes residual stresses in the composite which in turn are transferred to the adhesive interface. The deleterious effects of this stress environment include compromise of the interface itself and the decrease in the mechanical properties of the cured composite. Novel materials which claim to produce less shrinkage have been presented as a new class of restorative materials that could reduce the effects of this problem. One difficulty in assessing the actual in vivo benefits of these new materials is the fact that there is currently no direct way to measure the stress environment at the composite/tooth clinical interface. Computer modeling using finite element analysis (FEA) could provide helpful information regarding the clinical stress performance of dental composites. The purpose of this study was to develop a model that accurately simulates the nonlinear polymerization behavior of light-cured dental composites using a commercial FEA program, which could be accessible for future research. Two phases were needed to accomplish this purpose. First, a data collection phase included volumetric shrinkage, shrinkage stress, tooth analog strain, and dynamic mechanical analysis experiments. Three composites, a standard methacrylate(Z250) and two experimental low stress epoxy-based composites (oxirane and silorane), were tested. The experimental results revealed an intriguing range of polymerization behavior exhibited by the three composites, indicating that the development of a low stress composite is possible. The information gathered from this phase supplied the necessary material input for the computer modeling, and provided empirical validation data for the model solutions. In the second modeling phase, an FEA approach based on a elastic/viscoplastic material model was used to

  12. A Review: Development of a Microdose Model for Analysis of Adaptive Response and Bystander Dose Response Behavior

    PubMed Central

    Leonard, Bobby E.

    2008-01-01

    Prior work has provided incremental phases to a microdosimetry modeling program to describe the dose response behavior of the radio-protective adaptive response effect. We have here consolidated these prior works (Leonard 2000, 2005, 2007a, 2007b, 2007c) to provide a composite, comprehensive Microdose Model that is also herein modified to include the bystander effect. The nomenclature for the model is also standardized for the benefit of the experimental cellular radio-biologist. It extends the prior work to explicitly encompass separately the analysis of experimental data that is 1.) only dose dependent and reflecting only adaptive response radio-protection, 2.) both dose and dose-rate dependent data and reflecting only adaptive response radio-protection for spontaneous and challenge dose damage, 3.) only dose dependent data and reflecting both bystander deleterious damage and adaptive response radio-protection (AR-BE model). The Appendix cites the various applications of the model. Here we have used the Microdose Model to analyze the, much more human risk significant, Elmore et al (2006) data for the dose and dose rate influence on the adaptive response radio-protective behavior of HeLa x Skin cells for naturally occurring, spontaneous chromosome damage from a Brachytherapy type 125I photon radiation source. We have also applied the AR-BE Microdose Model to the Chromosome inversion data of Hooker et al (2004) reflecting both low LET bystander and adaptive response effects. The micro-beam facility data of Miller et al (1999), Nagasawa and Little (1999) and Zhou et al (2003) is also examined. For the Zhou et al (2003) data, we use the AR-BE model to estimate the threshold for adaptive response reduction of the bystander effect. The mammogram and diagnostic X-ray induction of AR and protective BE are observed. We show that bystander damage is reduced in the similar manner as spontaneous and challenge dose damage as shown by the Azzam et al (1996) data. We cite

  13. Viscous flow and crystallization behavior of selected lunar compositions

    NASA Technical Reports Server (NTRS)

    Cukierman, M.; Klein, L.; Scherer, G.; Hopper, R. W.; Uhlmann, D. R.

    1973-01-01

    The flow characteristics of lunar compositions 15555 and 68502 have been determined over a wide range of viscosity. The temperature ranges covered by the measurements are 1201-1410 and 622-695 C for the 15555 composition and 1261-1515 and 725-840 C for 68502 composition. Reliable data could not be obtained over the intermediate ranges of temperature because of the occurrence of crystallization. The experimental data in the high temperature regions are found to be in close agreement with predictions of the semiempirical model of Bottinga and Weill. The results on these compositions are compared with previous data on other lunar compositions and on anorthite; and the importance of the flow behavior in interpreting lunar flows and phase morphologies is emphasized. Data are also reported on the kinetics of crystallization of the 15555 composition over the temperature interval from 700 to 1020 C.

  14. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.

    1992-01-01

    The effects of different fiber shapes on the behavior of metal matrix composites is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers in a three by three unit cell array of a SiC/Ti-15-3 metal matrix composite is used in the analysis. The model is employed to represent five fiber shapes that include a circle, an ellipse, a kidney, and two different cross shapes. The distribution of stresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis using the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes. In general, fiber dominated properties are not affected by fiber geometry and matrix dominated properties are only moderately affected.

  15. Fatigue behavior of SiC reinforced titanium composites

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Grimes, H. H.

    1979-01-01

    The low cycle axial fatigue properties of 25 and 44 fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650 deg C. The S-N curves for the composites showed no anticipated improvement over bulk matrix behavior at room temperature. Although axial and transverse tensile strength results suggest a degradation in SiC fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. The reduced matrix behavior was due, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques and to the large residual tensile stresses that can exist in fiber reinforced matrices. The effects of fatigue testing at high temperature are discussed.

  16. Fatigue behavior of SiC reinforced titanium composites

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Grimes, H. H.

    1979-01-01

    The low cycle axial fatigue properties of 25 and 44 fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650 C. At room temperature, the S-N curves for the composites showed no anticipated improvement over bulk matrix behavior. Although axial and transverse tensile strength results suggest a degradation in SiC fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. Microstructural studies indicate that the reduced matrix behavior was due, in part, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques. Another possible contributing factor is the large residual tensile stresses that can exist in fiber-reinforced matrices. These effects, as well as the effects of fatigue testing at high temperature, are discussed.

  17. Design of smart composite platforms for adaptive trust vector control and adaptive laser telescope for satellite applications

    NASA Astrophysics Data System (ADS)

    Ghasemi-Nejhad, Mehrdad N.

    2013-04-01

    This paper presents design of smart composite platforms for adaptive trust vector control (TVC) and adaptive laser telescope for satellite applications. To eliminate disturbances, the proposed adaptive TVC and telescope systems will be mounted on two analogous smart composite platform with simultaneous precision positioning (pointing) and vibration suppression (stabilizing), SPPVS, with micro-radian pointing resolution, and then mounted on a satellite in two different locations. The adaptive TVC system provides SPPVS with large tip-tilt to potentially eliminate the gimbals systems. The smart composite telescope will be mounted on a smart composite platform with SPPVS and then mounted on a satellite. The laser communication is intended for the Geosynchronous orbit. The high degree of directionality increases the security of the laser communication signal (as opposed to a diffused RF signal), but also requires sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum increases the data transmission rates, but laser systems require large amounts of power, which increases the mass and complexity of the supporting systems. In addition, the laser communication on the Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also addresses the design of an active composite platform to be used to simultaneously point and stabilize an intersatellite laser communication telescope with micro-radian pointing resolution. The telescope is a Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary). The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or else the optical properties of the system will be severely degraded. The alignment will also have to be maintained during thruster firings, which will require vibration suppression capabilities of the system as well. The innovative platform has been

  18. Treating Individuals With Intellectual Disabilities and Challenging Behaviors With Adapted Dialectical Behavior Therapy

    PubMed Central

    Brown, Julie F.; Brown, Milton Z.; Dibiasio, Paige

    2013-01-01

    Approximately one third of adults with intellectual and developmental disabilities have emotion dysregulation and challenging behaviors (CBs). Although research has not yet confirmed that existing treatments adequately reduce CBs in this population, dialectical behavior therapy (DBT) holds promise, as it has been shown to effectively reduce CBs in other emotionally dysregulated populations. This longitudinal single-group pilot study examined whether individuals with impaired intellectual functioning would show reductions in CBs while receiving standard DBT individual therapy used in conjunction with the Skills System (DBT-SS), a DBT emotion regulation skills curriculum adapted for individuals with cognitive impairment. Forty adults with developmental disabilities (most of whom also had intellectual disabilities) and CBs, including histories of aggression, self-injury, sexual offending, or other CBs, participated in this study. Changes in their behaviors were monitored over 4 years while in DBT-SS. Large reductions in CBs were observed during the 4 years. These findings suggest that modified DBT holds promise for effectively treating individuals with intellectual and developmental disabilities. PMID:23914278

  19. Behaviorally mediated, warm adaptation: a physiological strategy when mice behaviorally thermoregulate.

    PubMed

    Gordon, Christopher J; Aydin, Cenk; Repasky, Elizabeth A; Kokolus, Kathleen M; Dheyongera, Geoffrey; Johnstone, Andrew F M

    2014-08-01

    Laboratory mice housed under standard vivarium conditions with an ambient temperature (Ta) of ~22°C are likely to be cold stressed because this Ta is below their thermoneutral zone (TNZ). Mice raised at Tas within the TNZ adapt to the warmer temperatures, developing smaller internal organs and longer tails compared to mice raised at 22°C. Since mice prefer Tas equal to their TNZ when housed in a thermocline, we hypothesized that mice reared for long periods (e.g., months) in a thermocline would undergo significant changes in organ development and tail length as a result of their thermoregulatory behavior. Groups of three female BALB/c mice at an age of 37 days were housed together in a thermocline consisting of a 90cm long aluminum runway with a floor temperature ranging from 23 to 39°C. Two side-by-side thermoclines allowed for a total of 6 mice to be tested simultaneously. Control mice were tested in isothermal runways maintained at a Ta of 22°C. All groups were given cotton pads for bedding/nest building. Mass of heart, lung, liver, kidney, brain, and tail length were assessed after 73 days of treatment. Mice in the thermocline and control (isothermal) runways were compared to cage control mice housed 3/cage with bedding under standard vivarium conditions. Mice in the thermocline generally remained in the warm end throughout the daytime with little evidence of nest building, suggesting a state of thermal comfort. Mice in the isothermal runway built elaborate nests and huddled together in the daytime. Mice housed in the thermocline had significantly smaller livers and kidneys and an increase in tail length compared to mice in the isothermal runway as well as when compared to the cage controls. These patterns of organ growth and tail length of mice in the thermocline are akin to warm adaptation. Thus, thermoregulatory behavior altered organ development, a process we term behaviorally mediated, warm adaptation. Moreover, the data suggest that the standard

  20. A quantitative evolutionary theory of adaptive behavior dynamics.

    PubMed

    McDowell, J J

    2013-10-01

    The idea that behavior is selected by its consequences in a process analogous to organic evolution has been discussed for over 100 years. A recently proposed theory instantiates this idea by means of a genetic algorithm that operates on a population of potential behaviors. Behaviors in the population are represented by numbers in decimal integer (phenotypic) and binary bit string (genotypic) forms. One behavior from the population is emitted at random each time tick, after which a new population of potential behaviors is constructed by recombining parent behavior bit strings. If the emitted behavior produced a benefit to the organism, then parents are chosen on the basis of their phenotypic similarity to the emitted behavior; otherwise, they are chosen at random. After parent behavior recombination, the population is subjected to a small amount of mutation by flipping random bits in the population's bit strings. The behavior generated by this process of selection, reproduction, and mutation reaches equilibrium states that conform to every empirically valid equation of matching theory, exactly and without systematic error. These equations are known to describe the behavior of many vertebrate species, including humans, in a variety of experimental, naturalistic, natural, and social environments. The evolutionary theory also generates instantaneous dynamics and patterns of preference change in constantly changing environments that are consistent with the dynamics of live-organism behavior. These findings support the assertion that the world of behavior we observe and measure is generated by evolutionary dynamics. PMID:24219847

  1. Linking Screening for Emotional and Behavioral Problems to Problem-Solving Efforts: An Adaptive Model of Behavioral Assessment

    ERIC Educational Resources Information Center

    Volpe, Robert J.; Briesch, Amy M.; Chafouleas, Sandra M.

    2010-01-01

    This paper addresses several objectives of the special issue on universal screening by addressing gaps in the current research base concerning universal screening for mental, emotional, and behavioral health and by providing a framework for addressing the limitations of extant approaches. Specifically, an adaptive model of behavioral assessment…

  2. Brief Report: The Relationship between Language Skills, Adaptive Behavior, and Emotional and Behavior Problems in Pre-Schoolers with Autism

    ERIC Educational Resources Information Center

    Park, Carlie J.; Yelland, Gregory W.; Taffe, John R.; Gray, Kylie M.

    2012-01-01

    This study investigated the relationship between structural language skills, and communication skills, adaptive behavior, and emotional and behavior problems in pre-school children with autism. Participants were aged 3-5 years with autism (n = 27), and two comparison groups of children with developmental delay without autism (n = 12) and typically…

  3. Damping behavior of Discontinuous Fiber Reinforced Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Haldar, Amit Kumar; Aggarwal, Ishan; Batra, N. K.

    2010-11-01

    Discontinuous fiber reinforced composites are being used in many antivibration applications due to their time and temperature dependent specific mechanical properties. For utilization of this material to specific engineering applications there is a need to understand the damping behavior of composites under dynamic loading. For this work, unreinforced and 20% long and short reinforced glass fiber polypropylene composite materials were tested for free transverse vibration damping characteristics under static as well as fatigue loading conditions. The damping characteristics are quantified by decay pattern and natural frequency. Presence of reinforced fibers increases the damping capacity. Among reinforcements, short fiber reinforced polypropylene shows increased damping capacity then long glass fiber reinforced polypropylene.

  4. Behavior of Plastic Bonded Composite Explosives During High Acceleration

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Y.

    1998-03-01

    The mechanical behavior of plastic bonded composite explosives has been studied during high acceleration in an ultracentrifuge. The pressed explosives studied include LX-14 [95% HMX (cyclotetramethylene- tetranitramine), 5% Estane], Composition A3 type II [91% RDX (cyclotrimethylene-trinitramine), 99% BDNPF (bis-dinitropropyl acetal formal), 6% CAB (cellulose acetate butyrate)], and PAX-3 (85% HMX, 9% BDNPF, 6% CAB/25% Aluminum). The fracture strength of LX-14 is greater than all pressed explosives studied to date. The fracture strength of Composition A3 type II is smaller than all pressed explosives studied to date.

  5. Tensile and compressive behavior of a swirl mat composite

    SciTech Connect

    Ruggles, M.B.

    1998-07-01

    The Durability of Lightweight Composite Structures Project was established at Oak Ridge National Laboratory (ORNL) by the US Department of Energy to provide the experimentally-based, durability-driven design guidelines necessary to assure long-term structural integrity of automotive composite components. The initial focus of the ORNL Durability Project was on one representative reference material--an isocyanurate (polyurethane) reinforced with continuous strand, swirl-mat E-glass. The present report describes tensile and compressive testing and results for the reference composite. Behavior trends and proportional limit are established for both tension and compression. Damage development due to tensile loading and strain rate effects are discussed.

  6. The Classroom Adaptation Scale: A Behavior Rating Scale Designed to Screen Primary Grade Children for School Adaptation Problems.

    ERIC Educational Resources Information Center

    Virbickis, Joseph A.

    After a brief historical review of the background and research, the paper focuses on development of a teacher-administered behavior rating scale to screen for school adaptation problems on a large scale basis using as Ss 15 primary grade teachers and their ratings of 315 primary grade children (ages 6-to-10 years) in their classes. A 16-item…

  7. Multigroup Confirmatory Factor Analysis for the Adaptive Behavior Assessment System-II Parent Form, Ages 5-21

    ERIC Educational Resources Information Center

    Wei, Youhua; Oakland, Thomas; Algina, James

    2008-01-01

    The AAIDD has promulgated various models of adaptive behavior, including its 1992 model stressing 10 adaptive skills and its 2002 model that highlighted three conceptual domains. In previous studies on the Adaptive Behavior Assessment System-II (ABAS-II), researchers found support for a model including both 10 adaptive skills and three conceptual…

  8. Adapting the Behavior Education Program for Preschool Settings

    ERIC Educational Resources Information Center

    Steed, Elizabeth A.

    2011-01-01

    Behavior Education Program (BEP) is the most researched targeted intervention that is used in schoolwide positive behavior intervention and supports (PBIS). It is a daily check-in and check-out system in which students receive extra attention for positive social behavior throughout their school day. This extra attention is intended to prevent…

  9. Friction and wear behavior of aluminum and composite airplane skins

    NASA Technical Reports Server (NTRS)

    Jackson, K. E.

    1984-01-01

    Friction and wear behavior was determined for small skin specimens under abrasive loading conditions typical of those occurring on the underside of a transport airplane during emergency belly landing. A test apparatus consisting of a standard belt sander provided the sliding surface. Small test specimens constructed of aluminum, standard graphite-epoxy composite, aramid-epoxy composite, and toughened-resin composites were tested undar a range of pressures, belt velocities, and belt-surface textures. The effects of these test variables on the wear rate and the coefficient of friction are discussed and comparisons are made between the composite materials and aluminum. The effect of fiber orientation in the composite materials on wear rate was also investigated. In addition, tests were performed in which thermocouples were imbedded into the various test specimens to obtain temperature-time histories during abrasion.

  10. Squeeze flow and compaction behavior of toughened polyimide matrix composites

    NASA Technical Reports Server (NTRS)

    Lee, Byung Lip; Pater, R.; Soucek, M. D.

    1991-01-01

    The main emphasis was placed upon the squeeze flow and compaction behavior of the Lewis Research Center (LaRC) research project series polyimide matrix composites. The measurement of squeeze film flow behavior was performed by a plastometer which monitors the change of thickness of a prepreg specimen laid between two parallel plates under the specified temperature and pressure history. A critical evaluation of the plastometer data was attempted by examining the morphology of the specimen at various points during the squeeze flow. The effects of crosslinks (Mc) of resin, imidization (B-ataging) condition, and pressure on the squeeze flow behavior were examined. Results are given.

  11. Computational simulation of high temperature metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Chamis, Christos C.

    1991-01-01

    Computational procedures are described to simulate the thermal and mechanical behavior of high temperature metal matrix composite (HT MMC) in the following four broad areas: (1) behavior of HT MMC from micromechanics to laminate; (2) HT MMC structural response for simple and complex structural components; (3) HT MMC microfracture; and (4) tailoring of HT MMC behavior for optimum specific performance. Representative results from each area are presented to illustrate the effectiveness of the computational simulation procedures. Relevant reports are referenced for extended discussion regarding the specific area.

  12. Composition and adaptation in the life of Robert Schumann.

    PubMed

    Graves, John S

    2005-01-01

    The composer Robert Schumann, who suffered from bipolar disorder, utilized his impressive musical and literary talents in attempts to adapt to multiple developmental traumas, separations, and losses as well as to the ongoing ravages of his mood disorder. By analyzing several of his Lieder, the author formulates and describes several defense mechanisms involved in these adaptations. These include identification with the lost object, the use of transitional objects and phenomena, sublimation, denial, minimization, idealization, playfulness, and the employment of healthy obsessive traits. Schumann utilized these adaptive defenses successfully for a brief period, thus coping with a difficult separation from his fiancée, Clara. Ultimately, however, he was unable to experience mature mourning regarding the deaths of several family members. The author, drawing on his extensive experience with treating bipolar individuals in outpatient settings, discusses some of the difficulties that many bipolar patients like Schumann have with mourning, including early developmental vulnerabilities to separation and loss, the disorganizing effects of bipolar mood episodes on cognition and self-coherence, the need to camouflage affects reminiscent of bipolar mood episodes, and experiencing these affects and mood episodes as traumatic reoccurrences. By studying the biographies of creative individuals such as Schumann, clinicians can expand their appreciation of their patients' adaptive capacities and thus assist them in restoring a sense of hope and vitality in their lives. PMID:16370792

  13. Adaptive categorization of ART networks in robot behavior learning using game-theoretic formulation.

    PubMed

    Fung, Wai-keung; Liu, Yun-hui

    2003-12-01

    Adaptive Resonance Theory (ART) networks are employed in robot behavior learning. Two of the difficulties in online robot behavior learning, namely, (1) exponential memory increases with time, (2) difficulty for operators to specify learning tasks accuracy and control learning attention before learning. In order to remedy the aforementioned difficulties, an adaptive categorization mechanism is introduced in ART networks for perceptual and action patterns categorization in this paper. A game-theoretic formulation of adaptive categorization for ART networks is proposed for vigilance parameter adaptation for category size control on the categories formed. The proposed vigilance parameter update rule can help improving categorization performance in the aspect of category number stability and solve the problem of selecting initial vigilance parameter prior to pattern categorization in traditional ART networks. Behavior learning using physical robot is conducted to demonstrate the effectiveness of the proposed adaptive categorization mechanism in ART networks. PMID:14622873

  14. The effect of resist material composition on development behavior

    NASA Astrophysics Data System (ADS)

    Minegishi, Shinya; Itani, Toshiro

    2015-03-01

    The relation between resist composition and its development behavior was evaluated. The effect of a hydrophobic unit on a resist and on its development behavior was systematically investigated. The resist was exposed to extreme ultraviolet (EUV) or electron beam (EB) exposure, and the development behavior of the film was observed by high-speed atomic force microscopy (HS-AFM). The introduction of a hydrophobic group in the resist resulted in diminished swelling behavior and uniform dissolution. The resist resin cluster shape was also altered by the introduction of the hydrophobic group. These behaviors imply that the resin-resin and resin-tetramethylammonium hydroxide solution interactions differ. EUV lithography suffers from the photon issue that causes stochastic uniformity; however, in this study, we demonstrate the feasibility of achieving a better uniformity of resist patterning by altering the resist formulation.

  15. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.; Chamis, C. C.

    1992-01-01

    The effects of different fiber shapes on the behavior of a SiC/Ti-15 metal matrix composite is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers is used in the analysis. The model is employed to represent five different fiber shapes: a circle, an ellipse, a kidney, and two different cross shapes. The distribution of microstresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis for the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes and assess their potential benefits. No clear benefits result from different fiber shapes though there are some increases/decreases in isolated properties.

  16. Hybrid composites prepared from Industrial waste: Mechanical and swelling behavior.

    PubMed

    Ahmed, Khalil

    2015-03-01

    In this assessment, hybrid composites were prepared from the combination of industrial waste, as marble waste powder (MWP) with conventional fillers, carbon black (CB) as well as silica as reinforcing material, incorporated with natural rubber (NR). The properties studied were curing, mechanical and swelling behavior. Assimilation of CB as well as silica into MWP containing NR compound responded in decreasing the scorch time and cure time besides increasing in the torque. Additionally, increasing the CB and silica in their respective NR hybrid composite increases the tensile, tear, modulus, hardness, and cross-link density, but decreases the elongation and swelling coefficient. The degradation property e.g., thermal aging of the hybrid composite was also estimated. The overall behavior at 70 °C aging temperature signified that the replacement of MS by CB and silica improved the aging performance. PMID:25750756

  17. Hybrid composites prepared from Industrial waste: Mechanical and swelling behavior

    PubMed Central

    Ahmed, Khalil

    2013-01-01

    In this assessment, hybrid composites were prepared from the combination of industrial waste, as marble waste powder (MWP) with conventional fillers, carbon black (CB) as well as silica as reinforcing material, incorporated with natural rubber (NR). The properties studied were curing, mechanical and swelling behavior. Assimilation of CB as well as silica into MWP containing NR compound responded in decreasing the scorch time and cure time besides increasing in the torque. Additionally, increasing the CB and silica in their respective NR hybrid composite increases the tensile, tear, modulus, hardness, and cross-link density, but decreases the elongation and swelling coefficient. The degradation property e.g., thermal aging of the hybrid composite was also estimated. The overall behavior at 70 °C aging temperature signified that the replacement of MS by CB and silica improved the aging performance. PMID:25750756

  18. Adapted Dialectical Behavior Therapy for Adolescents with Self-injurious Thoughts and Behaviors.

    PubMed

    Courtney, Darren B; Flament, Martine F

    2015-07-01

    The purpose of this study was to explore clinical changes observed in suicidal adolescents treated with an adapted form of Dialectical Behavior Therapy for adolescents (A-DBT-A) in a tertiary care setting. We conducted an open-label naturalistic study including 61 adolescents with self-injurious thoughts and behaviors and associated features of borderline personality disorder, who underwent a 15-week course of A-DBT-A. Pre- and post-treatment measures were administered, the primary outcome being the total score on the Suicidal Ideas Questionnaire. Self-harm, symptoms of borderline personality disorder, resiliency measures, predictors of response, and predictors of attrition were also explored. Among participants who completed post-treatment measures, we found a significant reduction in suicidal ideation (n = 31, p < 0.001). Secondary outcomes also suggested improvement. Baseline substance use predicted attrition (HR 2.51; 95% CI 1.03-6.14; p < 0.05), as did baseline impulsivity score on the Life Problems Inventory (HR 1.03; 95% CI 1.004-1.06; p < 0.05). Overall, we observed clinical improvements in adolescents receiving A-DBT-A. PMID:26075841

  19. The Development of Adaptive Behavior in Toddlers and Preschoolers with Fragile X versus Autism

    PubMed Central

    McCary, Lindsay M.; Machlin, Laura; Roberts, Jane E.

    2014-01-01

    Although there is extensive research in the early detection of autism, no study has compared the adaptive behavior of young children with fragile X syndrome (FXS) and children with autism across ages. We investigated the cross-sectional development of adaptive behavior in children with FXS and children with autism between 18 and 83 months of age. Analyses revealed a significant relationship between age and adaptive behavior standard scores for children with FXS, with decreased performance across ages. Analyses also revealed that children with FXS had a relatively flat performance across domains while children with autism are typically more variable with lower scores in the communication domain relative to other domains. Delays in adaptive behavior were evident for children with FXS and children with autism at 24 months of age as reported in previous literature. Implications and future directions are discussed. PMID:25191537

  20. Pseudoelastic behavior of Cu-Ni composite nanowires

    SciTech Connect

    Mastorakos, Ioannis N.; Zbib, Hussein M.; Bahr, David F.; Parsons, Jessica; Faisal, Mased

    2009-01-26

    We investigate the pseudoelastic behavior at room temperature of composite nanowires using molecular dynamics simulations. The nanowires are composed of a nickel core surrounded by a copper shell, leading to high coherency stresses. The coherency and surface stresses cause the nanowires to undergo a lattice reorientation, by twinning, from <001> to <110> during relaxation. Nanowires of different cross-sectional areas (varying from 2.17x2.17 up to 2.9x2.9 nm{sup 2}) were studied. In all cases, under tensile loading, the nanowires reorient to <001> and then under unloading reorient back to <110>, thus exhibiting pseudoelastic behavior. This behavior is more pronounced in composite nanowires with a coherent interface than for single crystal nanowires.

  1. Constitutive behavior of particle-polymer binder composite

    SciTech Connect

    Zhang, D. Z.; Ma, X.

    2004-01-01

    A particle-binder composite can behave as a continuum solid and can also exhibit significant characters of dense granular flow depending on deformation conditions. When it behaves as continuum solid, polymer binder properties, especially the short time stress relaxation, significantly affects shock wave propagation through the composite. A constitutive model has been developed to account for the effects of the short time stress relaxation. The model compares well with experimental data. The model however does not consider the failure mechanisms of the material. The failure of the material closely depends on the manufacturing process. During the manufacturing process the binder bounding particles has not been cured while during the material failure process the binder bounds have already been destroyed or significantly weaken. Under these circumstances the composite flows like a dense granular material. The methods used in the studies of dense granular flow are introduced to study the particle-binder composite. Effects of interparticle forces on the macroscopic behavior of the material are studied. We find that the commonly used Voigt assumption in the study of composite materials is invalid for the particle-binder composite. Cohesion forces between particles determine the brittle or ductile behavior of the material during the failure process.

  2. Systematic Review of Engagement in Culturally Adapted Parent Training for Disruptive Behavior

    ERIC Educational Resources Information Center

    Butler, Ashley M.; Titus, Courtney

    2015-01-01

    This article reviews the literature reporting engagement (enrollment, attendance, and attrition) in culturally adapted parent training for disruptive behavior among racial/ethnic minority parents of children ages 2 to 7 years. The review describes the reported rates of engagement in adapted interventions and how engagement is analyzed in studies,…

  3. Development of Adaptive Behavior in Adolescents and Young Adults with Autism and Down Syndrome.

    ERIC Educational Resources Information Center

    Loveland, Katherine A.; Kelley, Michelle L.

    1988-01-01

    Sixteen individuals with autism and sixteen with Down's Syndrome, aged 10-29, were matched for verbal mental age. The groups' scores did not differ on the Vineland Adaptive Behavior Scales. However, the adaptive skills of Down's Syndrome individuals kept pace with mental age, while the skills of autistic subjects did not change. (Author/JDD)

  4. Adapted Behavior Therapy for Persistently Depressed Primary Care Patients: An Open Trial

    ERIC Educational Resources Information Center

    Uebelacker, Lisa A.; Weisberg, Risa B.; Haggarty, Ryan; Miller, Ivan W.

    2009-01-01

    Major depressive disorder is commonly treated in primary care settings. Psychotherapy occurring in primary care should take advantage of the unique aspects of the setting and must adapt to the problems and limitations of the setting. In this open trial, the authors used a treatment development model to adapt behavior therapy for primary care…

  5. Profiles of School Adaptation: Social, Behavioral and Academic Functioning in Sexually Abused Girls

    ERIC Educational Resources Information Center

    Daignault, Isabelle V.; Hebert, Martine

    2009-01-01

    Objectives: The short-term outcomes of child sexual abuse (CSA) on academic, behavioral and social adaptation at school were examined in order to: (1) document the proportion of sexually abused (SA) girls struggling in school and define the nature of their difficulties, (2) explore whether different profiles of school adaptation could be…

  6. Someone has to give in: theta oscillations correlate with adaptive behavior in social bargaining

    PubMed Central

    Zamorano, Francisco; López, Tamara; Rodriguez, Carlos; Cosmelli, Diego; Aboitiz, Francisco

    2014-01-01

    During social bargain, one has to both figure out the others’ intentions and behave strategically in such a way that the others’ behaviors will be consistent with one’s expectations. To understand the neurobiological mechanisms underlying these behaviors, we used electroencephalography while subjects played as proposers in a repeated ultimatum game. We found that subjects adapted their offers to obtain more acceptances in the last round and that this adaptation correlated negatively with prefrontal theta oscillations. People with higher prefrontal theta activity related to a rejection did not adapt their offers along the game to maximize their earning. Moreover, between-subject variation in posterior theta oscillations correlated positively with how individual theta activity influenced the change of offer after a rejection, reflecting a process of behavioral adaptation to the others’ demands. Interestingly, people adapted better their offers when they knew that they where playing against a computer, although the behavioral adaptation did not correlate with prefrontal theta oscillation. Behavioral changes between human and computer games correlated with prefrontal theta activity, suggesting that low adaptation in human games could be a strategy. Taken together, these results provide evidence for specific roles of prefrontal and posterior theta oscillations in social bargaining. PMID:24493841

  7. Comparison of Measures of Adaptive Behaviors in Preschool Children.

    ERIC Educational Resources Information Center

    Garrity, Linda I.; Servos, Andria B.

    1978-01-01

    Nonproblem and problem children were compared on Minnesota Child Development Inventory, Classroom Adjustment Rating Scale, Ottawa School Behavior Survey, AML Behavior Rating Scale, Teacher Rating Scale, and Denver Developmental Screening Test. Problem children scored significantly lower than nonproblem children on all measures. Minnesota Child…

  8. Pragmatics Driven Land Cover Service Composition Utilizing Behavior-Intention Model

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Chen, Jun; Xing, Huaqiao; Li, Songnian; Hu, Juju

    2016-06-01

    Web service composition is one of the key issues to develop a global land cover (GLC) information service portal. Aiming at the defect that traditional syntax and semantic service compositionare difficult to take pragmatic information into account, the paper firstly analyses three tiers of web service language and their succession relations, discusses the conceptual model of pragmatic web service, and proposes the idea of pragmatics-oriented adaptive composition method based on the analysis of some examples. On this basis it puts forward the pragmatic web service model based on Behavior-Intention through presetting and expression of service usability, users' intention, and other pragmatic information, develops the on-demand assembly method based on the agent theory and matching and reconstruction method on heterogeneous message, solves the key technological issue of algorithm applicability and heterogeneous message transformation in the process of covering web service composition on the ground, applies these methods into service combination, puts forward the pragmatic driven service composition method based on behavior-intention model, and effectively settles the issue of coordination and interaction of composite service invocation.

  9. METCAN updates for high temperature composite behavior: Simulation/verification

    NASA Technical Reports Server (NTRS)

    Lee, H.-J.; Murthy, P. L. N.; Chamis, Christos C.

    1991-01-01

    The continued verification (comparisons with experimental data) of the METCAN (Metal Matrix Composite Analyzer) computer code is updated. Verification includes comparisons at room and high temperatures for two composites, SiC/Ti-15-3 and SiC/Ti-6-4. Specifically, verification of the SiC/Ti-15-3 composite includes comparisons of strength, modulus, and Poisson's ratio as well as stress-strain curves for four laminates at room temperature. High temperature verification includes comparisons of strength and stress-strain curves for two laminates. Verification of SiC/Ti-6-4 is for a transverse room temperature stress-strain curve and comparisons for transverse strength at three temperatures. Results of the verification indicates that METCAN can be used with confidence to simulate the high temperature nonlinear behavior of metal matrix composites.

  10. Thermal shock behavior of fiber-reinforced ceramic composites

    SciTech Connect

    Singh, R.N.; Wang, H.

    1995-10-01

    The influence of fiber type and method of composite fabrication on the thermal shock behavior of 2-D fiber-reinforced ceramic composites is studied. Thermal shock tests are performed using a water quench technique, and thermal shock damage is characterized by both destructive and nondestructive techniques. It is shown that the composites possessed superior resistance to thermal shock damage than the monolithic ceramics. Catastrophic failure due to severe thermal stresses is prevented in composites and a significant portion of their original strength is retained at a quench temperature difference up to 1,000 C. These results along with an analysis of the thermal shock damage mechanism based on the destructive and nondestructive tests is described.

  11. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.

    1989-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared on a strength to density basis. The effect of fiber orientation on the creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  12. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1992-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  13. Time-dependent behavior of flax/starch composites

    NASA Astrophysics Data System (ADS)

    Varna, J.; Spārniņš, E.; Joffe, R.; Nättinen, K.; Lampinen, J.

    2012-02-01

    The time-dependent mechanical response of flax fiber-reinforced thermoplastic starch matrix composite and neat starch is analyzed. It is demonstrated that the response is highly sensitive to the relative humidity (with specific saturation moisture content in the composite) and special effort has to be made to keep it constant. It was found that the accumulation of micro-damage and the resulting reduction of the elastic modulus in this type of composite is limited. The highly nonlinear behavior of composites is related to the nonlinear viscoelasticity and viscoplasticity. These phenomena are accounted for by simple material models, as suggested in this study. The stress-dependent nonlinearity descriptors in these models are determined in creep and strain recovery tests at low as well as by high stresses.

  14. Kindergarten Children's Perceptions of "Anthropomorphic Artifacts" with Adaptive Behavior

    ERIC Educational Resources Information Center

    Kuperman, Asi; Mioduser, David

    2012-01-01

    In recent years, children from a kindergarten in central Israel have been exposed to learning experiences in technology as part of the implementation of a curriculum based on technological thinking, including topics related to behaving-adaptive-artifacts (e.g., robots). This study aims to unveil children's stance towards behaving artifacts:…

  15. Predicting Adaptive Behavior from the Bayley Scales of Infant Development.

    ERIC Educational Resources Information Center

    Hotard, Stephen; McWhirter, Richard

    To examine the proportion of variance in adaptive functioning predictable from mental ability, chronological age, I.Q., evidence of brain malfunction, seizure medication, and receptive and expressive language scores, 25 severely and profoundly retarded institutionalized persons (2-19 years old) were administered the Bayley Infant Scale Mental…

  16. Environmental effects on long term behavior of composite laminates

    NASA Technical Reports Server (NTRS)

    Singhal, S. N.; Chamis, C. C.

    1992-01-01

    Model equations are presented for approximate methods simulating the long-term behavior of composite materials and structures in hot/humid service environments. These equations allow laminate property upgradings with time, and can account for the effects of service environments on creep response. These methodologies are illustrated for various individual and coupled temperature/moisture, longitudinal/transverse, and composite material type cases. Creep deformation is noted to rise dramatically for cases of matrix-borne, but not of fiber-borne, loading in hot, humid environments; the coupled influence of temperature and moisture is greater than a mere combination of their individual influences.

  17. Illness behavior, social adaptation, and the management of illness. A comparison of educational and medical models.

    PubMed

    Mechanic, D

    1977-08-01

    Motivational needs and coping are important aspects of illness response. Clinicians must help guide illness response by suggesting constructive adaptive opportunities and by avoiding reinforcement of maladaptive patterns. This paper examines how the patient's search for meaning, social attributions, and social comparisons shapes adaptation to illness and subsequent disability. It proposes a coping-adaptation model involving the following five resources relevant to rehabilitation: economic assets, abilities and skills, defensive techniques, social supports, and motivational impetus. It is maintained that confusion between illness and illness behavior obfuscates the alternatives available to guide patients through smoother adaptations and resumption of social roles. PMID:328824

  18. Visual Behaviors and Adaptations Associated with Cortical and Ocular Impairment in Children.

    ERIC Educational Resources Information Center

    Jan, J. E.; Groenveld, M.

    1993-01-01

    This article shows the usefulness of understanding visual behaviors in the diagnosis of various types of visual impairments that are due to ocular and cortical disorders. Behaviors discussed include nystagmus, ocular motor dyspraxia, head position, close viewing, field loss adaptations, mannerisms, photophobia, and abnormal color perception. (JDD)

  19. Use of Vineland Adaptive Behavior Scales-II in Children with Autism--An Indian Experience

    ERIC Educational Resources Information Center

    Manohari, S. M.; Raman, Vijaya; Ashok, M. V.

    2013-01-01

    The Vineland Adaptive Behavior Scales-II Edition 2005 (Vineland-II) is useful in assessing abilities in autism spectrum disorder, where an accurate assessment of intelligence using standardized tools is difficult both due to the unique social and communication difficulties that these children present with and the behavioral issues that occur as…

  20. Making Sense by Building Sense: Kindergarten Children's Construction and Understanding of Adaptive Robot Behaviors

    ERIC Educational Resources Information Center

    Mioduser, David; Levy, Sharona T.

    2010-01-01

    This study explores young children's ability to construct and explain adaptive behaviors of a behaving artifact, an autonomous mobile robot with sensors. A central component of the behavior construction environment is the RoboGan software that supports children's construction of spatiotemporal events with an a-temporal rule structure. Six…

  1. Adaptive Skills and Maladaptive Behavior of Adolescents with Autism Spectrum Disorders Attending Special Schools in Singapore

    ERIC Educational Resources Information Center

    Poon, Kenneth K.

    2011-01-01

    This study describes the profile of and relationships between adaptive skills and the maladaptive behaviors exhibited by adolescents with autism spectrum disorders (ASD) attending special schools in Singapore. Parents of 20 adolescents with ASD attending special schools completed the Development Behavior Checklist (DBC; Einfeld & Tonge, 1995;…

  2. Adaptive Behavior of 4- through 8-Year-Old Children with Williams Syndrome.

    ERIC Educational Resources Information Center

    Mervis, Carolyn B.; Klein-Tasman, Bonita P.; Mastin, Michelle E.

    2001-01-01

    This study assessed the behavior of 41 4-through 8-year-olds with Williams syndrome. As expected, socialization and communication were relative strengths, whereas daily living skills and motor skills were relative weaknesses. Within socialization, interpersonal skills were stronger than play/leisure or coping skills. Adaptive behavior was not…

  3. Researching Travel Behavior and Adaptability: Using a Virtual Reality Role-Playing Game

    ERIC Educational Resources Information Center

    Watcharasukarn, Montira; Krumdieck, Susan; Green, Richard; Dantas, Andre

    2011-01-01

    This article describes a virtual reality role-playing game that was developed as a survey tool to collect travel behavior data and explore and monitor travel behavior adaptation. The Advanced Energy and Material Systems Laboratory has designed, developed a prototype, and tested such a game platform survey tool, called Travel Activity Constraint…

  4. Dialectical Behavior Therapy Adapted for the Vocational Rehabilitation of Significantly Disabled Mentally Ill Adults

    ERIC Educational Resources Information Center

    Koons, Cedar R.; Chapman, Alexander L.; Betts, Bette B.; O'Rourke, Beth; Morse, Nesha; Robins, Clive J.

    2006-01-01

    Twelve vocational rehabilitation clients with severe mental illness received a comprehensive adaptation of dialectical behavior therapy (DBT) delivered in a group format. Treatment consisted of 2 hours of standard DBT skills training per week and 90 minutes of diary card review, chain analysis, and behavioral rehearsal. Participants were selected…

  5. Simulation of Fatigue Behavior of High Temperature Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Tong, Mike T.; Singhal, Suren N.; Chamis, Christos C.; Murthy, Pappu L. N.

    1996-01-01

    A generalized relatively new approach is described for the computational simulation of fatigue behavior of high temperature metal matrix composites (HT-MMCs). This theory is embedded in a specialty-purpose computer code. The effectiveness of the computer code to predict the fatigue behavior of HT-MMCs is demonstrated by applying it to a silicon-fiber/titanium-matrix HT-MMC. Comparative results are shown for mechanical fatigue, thermal fatigue, thermomechanical (in-phase and out-of-phase) fatigue, as well as the effects of oxidizing environments on fatigue life. These results show that the new approach reproduces available experimental data remarkably well.

  6. Damping Behavior of Alumina Epoxy Nano-Composites

    NASA Astrophysics Data System (ADS)

    Katiyar, Priyanka; Kumar, Anand

    2016-05-01

    Polymer nano composites, consisting of a polymer matrix with nanoparticle filler, have been predicted to be one of the most beneficial applications of nanotechnology. Addition of nano particulates to a polymer matrix enhances its performance by capitalizing on the nature and properties of the nano-scale fillers. The damping behavior of composites with nano structured phases is significantly different from that of micro structured materials. Viscoelastic homopolymer exhibit a high material damping response over a relatively narrow range of temperature and frequencies. In many practical situations, a polymeric structure is required to possess better strength and stiffness properties together with a reasonable damping behavior. Viscoelastic polymers show higher loss factor beyond the glassy region which comes with a significant drop in the specific modulus. Addition of nano alumina particles to epoxy leads to improved strength and stiffness properties with an increase in glass transition temperature while retaining its damping capability. Experimental investigations are carried out on composite beam specimen fabricated with different compositions of alumina nano particles in epoxy to evaluate loss factor, tan δ. Impact damping method is used for time response analysis. A single point Laser is used to record the transverse displacement of a point on the composite beam specimen. The experimental results are compared with theoretical estimation of loss factor using Voigt estimation. The effect of inter phase is included in theoretical estimation of loss factor. The result reveals that the study of interface properties is very important in deriving the overall loss factor of the composite since interface occupies a significant volume fraction in the composite.

  7. Mechanical behavior of a composite reinforced overhead conductor

    NASA Astrophysics Data System (ADS)

    Alawar, Ahmad

    A new type of overhead conductor with a polymer composite core is evaluated in terms of the mechanical properties and operating characteristics. The conductor is composed of trapezoidal O'-tempered aluminum wires helically wound around a hybrid glass/carbon composite core produced by pultrusion. The conductor is intended for electrical power transmission, and is designated ACCC/TW, for aluminum conductor composite core/trapezoidal wire. Measurements of core properties and conductor sag at high temperatures were compared to conventional ACSR (aluminum conductor, steel-reinforced) of the same diameter. The mechanical properties of ACCC/TW, such as the tensile strength, CTE and SAG performance, showed superiority to conventional ACSR. The ACCC/TW conductor also exhibited greater ampacity than ACSR conductor at all operating temperatures. A modification to a Numerical Sag Method for predicting conductor sag is presented that accurately predicts the observed bilinear sag behavior of composite conductors. The modified method is called the Hybrid Sag Method (HSM). It is used to predict the sag of conductors with conventional designs. The HSM predictions are compared with those obtained using a conventional graphical sag method. The HSM shows virtually the same accuracy as the graphical method for predicting sag for composite conductors operated under specific conditions. The HSM predictions of sag are validated by comparisons with experimental measurements. Tensile strength and storage modulus were measured to determine the temperature dependence of the composite core from 20°-200°C. The storage modulus was measured by dynamic mechanical analysis (DMA) and showed temperature dependence nearly identical to the tensile strength for both composites. The correlation between storage modulus and tensile strength was analyzed in terms of the temperature-dependent matrix shear strength, and the storage modulus behavior is presented as a basis for projecting the strength

  8. Effects of adaptive protective behavior on the dynamics of sexually transmitted infections.

    PubMed

    Hayashi, Michael A L; Eisenberg, Marisa C

    2016-01-01

    Sexually transmitted infections (STIs) continue to present a complex and costly challenge to public health programs. The preferences and social dynamics of a population can have a large impact on the course of an outbreak as well as the effectiveness of interventions intended to influence individual behavior. In addition, individuals may alter their sexual behavior in response to the presence of STIs, creating a feedback loop between transmission and behavior. We investigate the consequences of modeling the interaction between STI transmission and prophylactic use with a model that links a Susceptible-Infectious-Susceptible (SIS) system to evolutionary game dynamics that determine the effective contact rate. The combined model framework allows us to address protective behavior by both infected and susceptible individuals. Feedback between behavioral adaptation and prevalence creates a wide range of dynamic behaviors in the combined model, including damped and sustained oscillations as well as bistability, depending on the behavioral parameters and disease growth rate. We found that disease extinction is possible for multiple regions where R0>1, due to behavior adaptation driving the epidemic downward, although conversely endemic prevalence for arbitrarily low R0 is also possible if contact rates are sufficiently high. We also tested how model misspecification might affect disease forecasting and estimation of the model parameters and R0. We found that alternative models that neglect the behavioral feedback or only consider behavior adaptation by susceptible individuals can potentially yield misleading parameter estimates or omit significant features of the disease trajectory. PMID:26362102

  9. Neural Adaptation and Behavioral Measures of Temporal Processing and Speech Perception in Cochlear Implant Recipients

    PubMed Central

    Zhang, Fawen; Benson, Chelsea; Murphy, Dora; Boian, Melissa; Scott, Michael; Keith, Robert; Xiang, Jing; Abbas, Paul

    2013-01-01

    The objective was to determine if one of the neural temporal features, neural adaptation, can account for the across-subject variability in behavioral measures of temporal processing and speech perception performance in cochlear implant (CI) recipients. Neural adaptation is the phenomenon in which neural responses are the strongest at the beginning of the stimulus and decline following stimulus repetition (e.g., stimulus trains). It is unclear how this temporal property of neural responses relates to psychophysical measures of temporal processing (e.g., gap detection) or speech perception. The adaptation of the electrical compound action potential (ECAP) was obtained using 1000 pulses per second (pps) biphasic pulse trains presented directly to the electrode. The adaptation of the late auditory evoked potential (LAEP) was obtained using a sequence of 1-kHz tone bursts presented acoustically, through the cochlear implant. Behavioral temporal processing was measured using the Random Gap Detection Test at the most comfortable listening level. Consonant nucleus consonant (CNC) word and AzBio sentences were also tested. The results showed that both ECAP and LAEP display adaptive patterns, with a substantial across-subject variability in the amount of adaptation. No correlations between the amount of neural adaptation and gap detection thresholds (GDTs) or speech perception scores were found. The correlations between the degree of neural adaptation and demographic factors showed that CI users having more LAEP adaptation were likely to be those implanted at a younger age than CI users with less LAEP adaptation. The results suggested that neural adaptation, at least this feature alone, cannot account for the across-subject variability in temporal processing ability in the CI users. However, the finding that the LAEP adaptive pattern was less prominent in the CI group compared to the normal hearing group may suggest the important role of normal adaptation pattern at the

  10. Corrosive wear behavior of 2014 and 6061 aluminum alloy composites

    SciTech Connect

    Varma, S.K.; Andrews, S.; Vasquez, G.

    1999-02-01

    Alloys of 2014 and 6061 aluminum reinforced with 0.1 volume fraction of alumina particles (VFAP) were subjected to impact scratching during a corrosive wear process. The transient currents generated due to the impact were measured in the two composites as well as in their respective monoliths. The effect of solutionizing time on the transient currents was correlated to the near surface microstructures, scratch morphology, concentration of quenched-in vacancies, and changes in grain sizes. It was observed that the transient current values increase with an increase in solutionizing time, indicating that the corrosive wear behavior is not strongly affected by the grain boundaries. However, a combination of pitting and the galvanic corrosion may account for the typical corrosive wear behavior exhibited by the alloys and the composites of this study.

  11. Effect of Composite Substrates on the Mechanical Behavior of Brazed Joints in Metal-Composite System

    NASA Technical Reports Server (NTRS)

    Singh, M.; Morscher, Gregory N.; Shpargel, Tarah; Asthana, Rajiv

    2006-01-01

    Advanced composite components are being considered for a wide variety of demanding applications in aerospace, space exploration, and ground based systems. A number of these applications require robust integration technologies to join dissimilar materials (metalcomposites) into complex structural components. In this study, three types of composites (C-C, C-SiC, and SiC-SiC) were vacuum brazed to commercially pure Ti using the active metal braze alloy Cusil-ABA (63Ag-35.3Cu-1.75Ti). Composite substrates with as fabricated and polished surfaces were used for brazing. The microstructure and composition of the joint, examined using scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), showed sound metallurgical bonding in all systems. The butt strap tensile (BST) test was performed on bonded specimens at room and elevated temperatures. Effect of substrate composition, interlaminar properties, and surface roughness on the mechanical properties and failure behavior of joints will be discussed.

  12. Neuropsychological, behavioral, and adaptive functioning of Swiss children with congenital central hypoventilation syndrome.

    PubMed

    Ruof, Helge; Hammer, Juerg; Tillmann, Bettina; Ghelfi, Daniela; Weber, Peter

    2008-11-01

    This study collected data about developmental problems in a cohort of children with congenital central hypoventilation syndrome. In 2003, in Switzerland, 11 children with this disease were registered. Nine of them gave their informed consent to participate in the study and were examined. Clinical assessments were conducted, including examinations of neuropsychological, behavioral, and adaptive functions using Kaufman-Assessment Battery for Children, Child Behavior Checklist, and Vineland Adaptive Behavior Scales. The mean age (+/- standard deviation) was 7.5 +/- 2.5 years. The cognitive tests showed problems in working memory functions with a near-to-normal full-range intelligence quotient (87.4 +/- 23.3). The children showed normal values (t-values < 67) on problem scales of behavior, although 5 of the 9 children showed elevated values on the attention and on the social interaction problem scales. Adaptive function problems were identified in communication and daily living skills. PMID:18984833

  13. Elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Wang, C.; Sun, C. T.; Gates, T. S.

    1990-01-01

    An elastic/viscoplastic constitutive model was used to characterize the nonlinear and rate dependent behavior of a continuous fiber-reinforced thermoplastic composite. This model was incorporated into a finite element program for the analysis of laminated plates and shells. Details on the finite element formulation with the proposed constitutive model were presented. The numerical results were compared with experimental data for uniaxial tension and three-point bending tests of (+ or - 45 deg)3s APC-2 laminates.

  14. Fracture behavior of glass fiber reinforced polymer composite

    SciTech Connect

    Avci, A.; Arikan, H.; Akdemir, A

    2004-03-01

    Chopped strand glass fiber reinforced particle-filled polymer composite beams with varying notch-to-depth ratios and different volume fractions of glass fibers were investigated in Mode I fracture using three-point bending tests. Effects of polyester resin content and glass fiber content on fracture behavior was also studied. Polyester resin contents were used 13.00%%, 14.75%, 16.50%, 18.00% and 19.50%, and glass fiber contents were 1% and 1.5% of the total weight of the polymer composite system. Flexural strength of the polymer composite increases with increase in polyester and fiber content. The critical stress intensity factor was determined by using several methods such as initial notch depth method, compliance method and J-integral method. The values of K{sub IC} obtained from these methods were compared.

  15. Investigation of Buckling Behavior of Composite Shell Structures with Cutouts

    NASA Astrophysics Data System (ADS)

    Arbelo, Mariano A.; Herrmann, Annemarie; Castro, Saullo G. P.; Khakimova, Regina; Zimmermann, Rolf; Degenhardt, Richard

    2015-12-01

    Thin-walled cylindrical composite shell structures can be applied in space applications, looking for lighter and cheaper launcher transport system. These structures are prone to buckling under axial compression and may exhibit sensitivity to geometrical imperfections. Today the design of such structures is based on NASA guidelines from the 1960's using a conservative lower bound curve generated from a database of experimental results. In this guideline the structural behavior of composite materials may not be appropriately considered since the imperfection sensitivity and the buckling load of shells made of such materials depend on the lay-up design. It is clear that with the evolution of the composite materials and fabrication processes this guideline must be updated and / or new design guidelines investigated. This need becomes even more relevant when cutouts are introduced to the structure, which are commonly necessary to account for access points and to provide clearance and attachment points for hydraulic and electric systems. Therefore, it is necessary to understand how a cutout with different dimensions affects the buckling load of a thin-walled cylindrical shell structure in combination with other initial geometric imperfections. In this context, this paper present some observations regarding the buckling load behavior vs. cutout size and radius over thickness ratio, of laminated composite curved panels and cylindrical shells, that could be applied in further recommendations, to allow identifying when the buckling of the structure is dominated by the presence of the cutout or by other initial imperfections.

  16. Multigroup Confirmatory Factor Analysis for the Teacher Form, Ages 5 to 21, of the Adaptive Behavior Assessment System-II

    ERIC Educational Resources Information Center

    Aricak, O. Tolga; Oakland, Thomas

    2010-01-01

    The American Association on Intellectual and Developmental Disabilities has promulgated various models of adaptive behavior, including its 1992 model that highlighted 10 adaptive skills and its 2002 model that highlighted three conceptual domains. The Adaptive Behavior Assessment System-II (ABAS-II) was designed to be consistent with these models.…

  17. Options for Managing Student Behavior: Adaptations for Individual Needs.

    ERIC Educational Resources Information Center

    Richardson, Rita C.; Evans, Elizabeth T.

    This paper applies principles of situational leadership theory to the management of student behavior problems. First, it summarizes situational leadership, noting the theory's premise that leaders must consider two important factors to gain acceptance and compliance in managing people--the maturity level of the individuals and the nature of the…

  18. Systematic Review of Engagement in Culturally Adapted Parent Training for Disruptive Behavior

    PubMed Central

    Butler, Ashley M.; Titus, Courtney

    2016-01-01

    This article reviews the literature reporting engagement (enrollment, attendance, and attrition) in culturally adapted parent training for disruptive behavior among racial/ethnic minority parents of children ages 2–7 years. The review describes the reported rates of engagement in adapted interventions and how engagement is analyzed in studies, methods to develop adaptations, and adaptations that have been implemented. Seven studies were identified. Parental engagement varied across and within studies. Only one study examined whether adaptations improved engagement compared to non-adapted intervention. Frequent methods to develop adaptations were building partnerships or conducting interviews/focus groups with minority parents or community members. Adaptations included addressing cultural beliefs (perceptions of parenting skills), values (interdependence), or experiences (immigration) that affect parenting or receptivity to interventions; ensuring racial/ethnic diversity of interventionists; and addressing cultural relevancy and literacy level of materials. Future research should examine engagement in adapted interventions compared to non-adapted interventions and examine factors (e.g., immigration status) that may moderate impact on engagement. PMID:27429537

  19. Resistance to exercise-induced weight loss: compensatory behavioral adaptations.

    PubMed

    Melanson, Edward L; Keadle, Sarah Kozey; Donnelly, Joseph E; Braun, Barry; King, Neil A

    2013-08-01

    In many interventions that are based on an exercise program intended to induce weight loss, the mean weight loss observed is modest and sometimes far less than what the individual expected. The individual responses are also widely variable, with some individuals losing a substantial amount of weight, others maintaining weight, and a few actually gaining weight. The media have focused on the subpopulation that loses little weight, contributing to a public perception that exercise has limited utility to cause weight loss. The purpose of the symposium was to present recent, novel data that help explain how compensatory behaviors contribute to a wide discrepancy in exercise-induced weight loss. The presentations provide evidence that some individuals adopt compensatory behaviors, that is, increased energy intake and/or reduced activity, that offset the exercise energy expenditure and limit weight loss. The challenge for both scientists and clinicians is to develop effective tools to identify which individuals are susceptible to such behaviors and to develop strategies to minimize their effect. PMID:23470300

  20. Resistance to exercise-induced weight loss: compensatory behavioral adaptations

    PubMed Central

    Melanson, Edward L.; Keadle, Sarah Kozey; Donnelly, Joseph E.; Braun, Barry; King, Neil A.

    2013-01-01

    In many interventions that are based on an exercise program intended to induce weight loss, the mean weight loss observed is modest and sometimes far less than the individual expected. The individual responses are also widely variable, with some individuals losing a substantial amount of weight, others maintaining weight, and a few actually gaining weight. The media have focused on the sub-population that loses little weight, contributing to a public perception that exercise has limited utility to cause weight loss. The purpose of the symposium was to present recent, novel data that help explain how compensatory behaviors contribute to a wide discrepancy in exercise-induced weight loss. The presentations provide evidence that some individuals adopt compensatory behaviors, i.e. increased energy intake and/or reduced activity, that offset the exercise energy expenditure and limit weight loss. The challenge for both scientists and clinicians is to develop effective tools to identify which individuals are susceptible to such behaviors, and to develop strategies to minimize their impact. PMID:23470300

  1. Dynamic mechanical behavior of boron carbide-based composites

    NASA Astrophysics Data System (ADS)

    Hayun, Shmulik; Frage, Nahum; Dariel, Moshe; Zaretsky, Eugene

    2007-06-01

    This presentation is concerned with the dynamic response of two types of boron carbide-based composites. The composites were fabricated by infiltration of compacted but unsintered B4C preforms and of partially sintered B4C skeletons by liquid Si. During the infiltration process, molten silicon reacts with the B4C phase resulting in the formation of the SiC and B12(B,C,Si)3 phases. Some residual silicon is also present in the infiltrated composites. The dynamic behavior was studied in planar impact experiments (impact velocities 100-1000 m/sec) using a 25 mm gas gun. The velocities of the sample-PMMA window interface were monitored continuously by VISAR. The composites failed completely in compression, at loads above their HEL (17-18 GPa). The spall strength, deduced from low-velocity impacts, ranged from 0.5 to 1.1 GPa, depending on the tensile strain rate. Scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) were used to analyze the fracture surface. The correlation between the microstructure of the infiltrated composites and their dynamic response is discussed.

  2. Parental genetic effects in a cavefish adaptive behavior explain disparity between nuclear and mitochondrial DNA.

    PubMed

    Yoshizawa, Masato; Ashida, Go; Jeffery, William R

    2012-09-01

    Epigenetic parental genetic effects are important in many biological processes but their roles in the evolution of adaptive traits and their consequences in naturally evolving populations remain to be addressed. By comparing two divergent blind cave-dwelling cavefish populations with a sighted surface-dwelling population (surface fish) of the teleost Astyanax mexicanus, we report here that convergences in vibration attraction behavior (VAB), the lateral line sensory receptors underlying this behavior, and the feeding benefits of this behavior are controlled by parental genetic effects, either maternal or paternal inheritance. From behavioral studies and mathematical evolutionary simulations, we further demonstrate that disparity in nuclear and mitochondrial DNA in one of these cavefish populations that has hybridized with surface fish can be explained by paternal inheritance of VAB. The results suggest that parental genetic effects in adaptive behaviors may be important factors in biasing mitochondrial DNA inheritance in natural populations that are subject to introgression. PMID:22946818

  3. Influence of composition gradients on weld metal creep behavior: An analysis based on laminate composites

    SciTech Connect

    Choi, I.

    1989-01-01

    The effects of weld metal microsegregation, as altered by post-weld heat treatments, on both low and high temperatures tensile properties were investigated on Monel alloy 400. Flat, all weld metal, tensile specimens were machined from single pass GTA welds and were heat treated in vacuum in the range of 600 C to 1000 C to produce samples with different composition gradients. Short-time tensile tests were run at room temperature and elevated temperature. Long-time constant load creep tests were performed at 500 C. The room temperature mechanical properties of the as-welded specimen and heat treated specimens were similar and thus unaffected by variations in composition gradients. In contrast, at high temperatures the steady state creep rates decreased, rupture strains increased, and rupture lives decreases with increases in heat treatment temperature, that is, with decreases in the amplitudes of composition gradients. The deformation behavior of solidified dendritic structure was modeled based on results obtained on laminate composites of nickel and copper. The laminates, prepared by roll bonding, were annealed to produce controlled composition gradients with dimensions equivalent to those observed in the weld metal. The steady state creep rates of laminate composites decreased with increases in heat treatment time, that is, with decreases in the amplitudes of composition gradients. To rationalize the creep properties of each component in laminate composites, nickel-copper solid solutions having systematic compositional variations were prepared and tested under the same conditions as the laminate composites. The creep rates of nickel-copper solid solutions showed a minimum with nickel composition.

  4. Effects of Fiber Coating Composition on Mechanical Behavior of Silicon Carbide Fiber-Reinforced Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Elderidge, Jeffrey I.

    1998-01-01

    Celsian matrix composites reinforced with Hi-Nicalon fibers, precoated with a dual layer of BN/SiC by chemical vapor deposition in two separate batches, were fabricated. Mechanical properties of the composites were measured in three-point flexure. Despite supposedly identical processing, the composite panels fabricated with fibers coated in two batches exhibited substantially different mechanical behavior. The first matrix cracking stresses (sigma(sub mc)) of the composites reinforced with fibers coated in batch 1 and batch 2 were 436 and 122 MPa, respectively. This large difference in sigma(sub mc) was attributed to differences in fiber sliding stresses(tau(sub friction)), 121.2+/-48.7 and 10.4+/-3.1 MPa, respectively, for the two composites as determined by the fiber push-in method. Such a large difference in values of tau(sub friction) for the two composites was found to be due to the difference in the compositions of the interface coatings. Scanning Auger microprobe analysis revealed the presence of carbon layers between the fiber and BN, and also between the BN and SiC coatings in the composite showing lower tau(sub friction). This resulted in lower sigma(sub mc) in agreement with the ACK theory. The ultimate strengths of the two composites, 904 and 759 MPa, depended mainly on the fiber volume fraction and were not significantly effected by tau(sub friction) values, as expected. The poor reproducibility of the fiber coating composition between the two batches was judged to be the primary source of the large differences in performance of the two composites.

  5. Complex Features in Lotka-Volterra Systems with Behavioral Adaptation

    NASA Astrophysics Data System (ADS)

    Tebaldi, Claudio; Lacitignola, Deborah

    Lotka-Volterra systems have played a fundamental role for mathematical modelling in many branches of theoretical biology and proved to describe, at least qualitatively, the essential features of many phenomena, see for example Murray [Murray 2002]. Furthermore models of that kind have been considered successfully also in quite different and less mathematically formalized context: Goodwin' s model of economic growth cycles [Goodwin 1967] and urban dynamics [Dendrinos 1992] are only two of a number of examples. Such systems can certainly be defined as complex ones and in fact the aim of modelling was essentially to clarify mechanims rather than to provide actual precise simulations and predictions. With regards to complex systems, we recall that one of their main feature, no matter of the specific definition one has in mind, is adaptation, i. e. the ability to adjust.

  6. Modeling bee swarming behavior through diffusion adaptation with asymmetric information sharing

    NASA Astrophysics Data System (ADS)

    Li, Jinchao; Sayed, Ali H.

    2012-12-01

    Honeybees swarm when they move to a new site for their hive. During the process of swarming, their behavior can be analyzed by classifying them as informed bees or uninformed bees, where the informed bees have some information about the destination while the uninformed bees follow the informed bees. The swarm's movement can be viewed as a network of mobile nodes with asymmetric information exchange about their destination. In these networks, adaptive and mobile agents share information on the fly and adapt their estimates in response to local measurements and data shared with neighbors. Diffusion adaptation is used to model the adaptation process in the presence of asymmetric nodes and noisy data. The simulations indicate that the models are able to emulate the swarming behavior of bees under varied conditions such as a small number of informed bees, sharing of target location, sharing of target direction, and noisy measurements.

  7. A Compositional Relevance Model for Adaptive Information Retrieval

    NASA Technical Reports Server (NTRS)

    Mathe, Nathalie; Chen, James; Lu, Henry, Jr. (Technical Monitor)

    1994-01-01

    There is a growing need for rapid and effective access to information in large electronic documentation systems. Access can be facilitated if information relevant in the current problem solving context can be automatically supplied to the user. This includes information relevant to particular user profiles, tasks being performed, and problems being solved. However most of this knowledge on contextual relevance is not found within the contents of documents, and current hypermedia tools do not provide any easy mechanism to let users add this knowledge to their documents. We propose a compositional relevance network to automatically acquire the context in which previous information was found relevant. The model records information on the relevance of references based on user feedback for specific queries and contexts. It also generalizes such information to derive relevant references for similar queries and contexts. This model lets users filter information by context of relevance, build personalized views of documents over time, and share their views with other users. It also applies to any type of multimedia information. Compared to other approaches, it is less costly and doesn't require any a priori statistical computation, nor an extended training period. It is currently being implemented into the Computer Integrated Documentation system which enables integration of various technical documents in a hypertext framework.

  8. The adaptive trade-off between detection and discrimination in cortical representations and behavior

    PubMed Central

    Ollerenshaw, Douglas R.; Zheng, He J. V.; Millard, Daniel C.; Wang, Qi; Stanley, Garrett B.

    2014-01-01

    SUMMARY It has long been posited that detectability of sensory inputs can be sacrificed in favor of improved discriminability, and that sensory adaptation may mediate this trade-off. The extent to which this trade-off exists behaviorally, and the complete picture of the underlying neural representations that likely subserve the phenomenon, remain unclear. In the rodent vibrissa system, an ideal observer analysis of cortical activity measured using voltage sensitive dye (VSD) imaging in anesthetized animals was combined with behavioral detection and discrimination tasks, thalamic recordings from awake animals, and computational modeling to show that spatial discrimination performance was improved following adaptation, but at the expense of the ability to detect weak stimuli. Together, these results provide direct behavioral evidence for the trade-off between detectability and discriminability, that this trade-off can be modulated through bottom-up sensory adaptation, and that these effects correspond to important changes in thalamocortical coding properties. PMID:24607233

  9. Static and quasi-static behavior of an adaptive system to compensate path errors for smart fiber placement

    NASA Astrophysics Data System (ADS)

    Perner, M.; Monner, H. P.; Krombholz, C.; Kruse, F. F.

    2015-04-01

    Smart fiber placement is an ambitious topic in current research for automated manufacturing of large-scale composite structures, e.g. wing covers. Adaptive systems get in focus to obtain a high degree of observability and controllability of the manufacturing process. In particular, vibrational issues and material failure have to be studied to significantly increase the production rate with no loss in accuracy of the fiber layup. As one contribution, an adaptive system has been developed to be integrated into the fiber placement head. It decouples the compaction roller from disturbances caused by misalignments, varying components' behavior over a large work area and acceleration changes during operation. Therefore, the smart system axially adapts the position of the compaction roller in case of disturbances. This paper investigates the behavior of the system to compensate quasi-static deviations from the desired path. In particular, the compensation efficiency of a constant offset, a linear drift with constant gradient and a single-curved drift is studied. Thus, the test bed with measurement devices and scenarios is explained. Based on the knowledge obtained by the experimental data, the paper concludes with a discussion of the proposed approach for its use under operating conditions and further implementation.

  10. Flight Test of Composite Model Reference Adaptive Control (CMRAC) Augmentation Using NASA AirSTAR Infrastructure

    NASA Technical Reports Server (NTRS)

    Gregory, Irene M.; Gadient, ROss; Lavretsky, Eugene

    2011-01-01

    This paper presents flight test results of a robust linear baseline controller with and without composite adaptive control augmentation. The flight testing was conducted using the NASA Generic Transport Model as part of the Airborne Subscale Transport Aircraft Research system at NASA Langley Research Center.

  11. Assessing heat-adaptive behaviors among older, urban-dwelling adults

    PubMed Central

    White-Newsome, Jalonne L.; Sánchez, Brisa N.; Parker, Edith A.; Dvonch, J. Timothy; Zhang, Zhenzhen; O’Neill, Marie S.

    2015-01-01

    Objectives Health studies have shown that the elderly are at a greater risk to extreme heat. The frequency and intensity of summer heat waves will continue to increase as a result of climate change. It is important that we understand the environmental and structural factors that increase heat vulnerability, as well as examine the behaviors used by the elderly to adapt to hot indoor temperatures. Study design From June 1 to August 31, 2009, residents in 29 homes in Detroit, MI, kept an hourly log of eight heat-adaptive behaviors: opening windows/doors, turning fans or the air conditioner on, changing clothes, taking a shower, going to the basement, the porch/yard, or leaving the house. Percentages of hourly behavior were calculated, overall and stratified by housing type and percent surface imperviousness. The frequency of behavior use, as a result of indoor and outdoor predetermined temperature intervals was compared to a reference temperature range of 21.1–23.8 °C. Results The use of all adaptive behaviors, except going to the porch or yard, was significantly associated with indoor temperature. Non-mechanical adaptations such as changing clothes, taking showers, and going outside or to the basement were rarely used. Residents living in high-rises and highly impervious areas reported a higher use of adaptive behaviors. The odds of leaving the house significantly increased as outdoor temperature increased. Conclusions These findings suggest that the full range of heat adaptation measures may be underused by the elderly and public health interventions need to focus on outreach to these populations. PMID:21782363

  12. Cybernetic control model from ethology for adaptive coordination of robot behaviors

    NASA Astrophysics Data System (ADS)

    Schlueter, Bernd

    1992-08-01

    In this paper we propose a cybernetic approach to behavior based robotics. We present a distributed adaptive control architecture for coordination of different motivations and behaviors of an autonomous vehicle. The system is based on the Zurich Model of Social Motivation, a cybernetic approach to mammalian behavior by the Swiss ethologist BISCHOF. Our system controls a simulated autonomous robot by teaching a reflective associative memory to propose an action based on the input of eight range sensors. The emerging behavior at every stage reflects the system's experience, and the robust in unexpected situations.

  13. ADAPTIVE BEHAVIORS IN YOUNG CHILDREN: A UNIQUE CULTURAL COMPARISON IN ITALY

    PubMed Central

    Taverna, Livia; Bornstein, Marc H.; Putnick, Diane L.; Axia, Giovanna

    2010-01-01

    On account of a series of unique historical events, the present-day denizens of South Tyrol inhabit a cultural, political, and linguistic autonomous region that intercalates Italians and Austrian/German Italians. We compared contemporary Italian and Austrian/German Italian girls' and boys' adaptive behaviors in everyday activities in this region. Using the Vineland Adaptive Behavior Scales, we first interviewed mothers about their children's communication, daily living, socialization, and motor skills. Main effects of local culture (and no interactions with gender) emerged: Austrian/German Italian children were rated higher than Italian children in both adaptive daily living and socialization skills. Next, we explored ethnic differences in childrearing. Austrian/German Italians reported fostering greater autonomy in their children than Italians, and children's autonomy was associated with their adaptive behavior. Children living in neighboring Italian and Austrian/German Italian cultural niches appear to experience subtle but consequentially different conditions of development that express themselves in terms of differing levels of adaptive behaviors. PMID:21532914

  14. Organizational Adaptative Behavior: The Complex Perspective of Individuals-Tasks Interaction

    NASA Astrophysics Data System (ADS)

    Wu, Jiang; Sun, Duoyong; Hu, Bin; Zhang, Yu

    Organizations with different organizational structures have different organizational behaviors when responding environmental changes. In this paper, we use a computational model to examine organizational adaptation on four dimensions: Agility, Robustness, Resilience, and Survivability. We analyze the dynamics of organizational adaptation by a simulation study from a complex perspective of the interaction between tasks and individuals in a sales enterprise. The simulation studies in different scenarios show that more flexible communication between employees and less hierarchy level with the suitable centralization can improve organizational adaptation.

  15. Profiles of classroom behavior in high schools: associations with teacher behavior management strategies and classroom composition.

    PubMed

    Pas, Elise T; Cash, Anne H; O'Brennan, Lindsey; Debnam, Katrina J; Bradshaw, Catherine P

    2015-04-01

    Although there has been considerable attention to the issue of classroom management and processes in educational reform models, there has been relatively limited research on these factors in high schools. The current study utilized observational data from 1262 classrooms in 52 high schools to examine teacher classroom management strategies and ratings of student compliance, engagement, and social disruption. Latent profile analysis (LPA) was conducted to examine specific patterns of classroom-wide student behavior in relation to teachers' use of classroom management strategies and classroom composition. The LPA revealed three distinct classroom behavioral profiles where students consistently met behavioral expectations (71%), inconsistently met expectations (23%), and were noncompliant (6%). Analyses indicated a functional association between patterns of student behavior and teachers' classroom management. In classrooms where students consistently met expectations, teachers provided more opportunities to respond and less disapproval and reactive behavioral management. Classrooms with noncompliant students had teachers who used the most disapproval and reactive behavior management. In addition, classrooms characterized as consistent had fewer males and more White students than classrooms characterized by inconsistent and noncompliant behaviors. These findings highlight the link between student patterns of behavior and teacher classroom management and have important implications for screening and professional development. PMID:25746823

  16. Spatiotemporal Spike Coding of Behavioral Adaptation in the Dorsal Anterior Cingulate Cortex

    PubMed Central

    Logiaco, Laureline; Quilodran, René; Procyk, Emmanuel; Arleo, Angelo

    2015-01-01

    The frontal cortex controls behavioral adaptation in environments governed by complex rules. Many studies have established the relevance of firing rate modulation after informative events signaling whether and how to update the behavioral policy. However, whether the spatiotemporal features of these neuronal activities contribute to encoding imminent behavioral updates remains unclear. We investigated this issue in the dorsal anterior cingulate cortex (dACC) of monkeys while they adapted their behavior based on their memory of feedback from past choices. We analyzed spike trains of both single units and pairs of simultaneously recorded neurons using an algorithm that emulates different biologically plausible decoding circuits. This method permits the assessment of the performance of both spike-count and spike-timing sensitive decoders. In response to the feedback, single neurons emitted stereotypical spike trains whose temporal structure identified informative events with higher accuracy than mere spike count. The optimal decoding time scale was in the range of 70–200 ms, which is significantly shorter than the memory time scale required by the behavioral task. Importantly, the temporal spiking patterns of single units were predictive of the monkeys’ behavioral response time. Furthermore, some features of these spiking patterns often varied between jointly recorded neurons. All together, our results suggest that dACC drives behavioral adaptation through complex spatiotemporal spike coding. They also indicate that downstream networks, which decode dACC feedback signals, are unlikely to act as mere neural integrators. PMID:26266537

  17. Spatiotemporal Spike Coding of Behavioral Adaptation in the Dorsal Anterior Cingulate Cortex.

    PubMed

    Logiaco, Laureline; Quilodran, René; Procyk, Emmanuel; Arleo, Angelo

    2015-08-01

    The frontal cortex controls behavioral adaptation in environments governed by complex rules. Many studies have established the relevance of firing rate modulation after informative events signaling whether and how to update the behavioral policy. However, whether the spatiotemporal features of these neuronal activities contribute to encoding imminent behavioral updates remains unclear. We investigated this issue in the dorsal anterior cingulate cortex (dACC) of monkeys while they adapted their behavior based on their memory of feedback from past choices. We analyzed spike trains of both single units and pairs of simultaneously recorded neurons using an algorithm that emulates different biologically plausible decoding circuits. This method permits the assessment of the performance of both spike-count and spike-timing sensitive decoders. In response to the feedback, single neurons emitted stereotypical spike trains whose temporal structure identified informative events with higher accuracy than mere spike count. The optimal decoding time scale was in the range of 70-200 ms, which is significantly shorter than the memory time scale required by the behavioral task. Importantly, the temporal spiking patterns of single units were predictive of the monkeys' behavioral response time. Furthermore, some features of these spiking patterns often varied between jointly recorded neurons. All together, our results suggest that dACC drives behavioral adaptation through complex spatiotemporal spike coding. They also indicate that downstream networks, which decode dACC feedback signals, are unlikely to act as mere neural integrators. PMID:26266537

  18. Composite Panel Postbuckling Behavior and General Model of Joints in Composite Structures

    NASA Technical Reports Server (NTRS)

    Zamula, G. N.; Kutinov, V. F.; Vasilyev, V. V.; Grishin, V. I.; Ierusalimsky, K. M.; Azikov, N. S.; Begeyev, T. K.

    1996-01-01

    The present paper is a final technical report on the research programme NCCW-73 accomplished within co-operation between NASA of the USA and GOSKOMOBORONPROM of Russia in the field of aeronautics. The report contains basic results of studies in two areas, 'Analysis of postbuckling behavior of composite panels' and 'Development of general model of joints in composite structures'; these results were obtained in conformity with requirements of NCCW-73. In addition, consideration is given to some related issues, and proposals for further studies are formulated.

  19. Group Selection as Behavioral Adaptation to Systematic Risk

    PubMed Central

    Zhang, Ruixun; Brennan, Thomas J.; Lo, Andrew W.

    2014-01-01

    Despite many compelling applications in economics, sociobiology, and evolutionary psychology, group selection is still one of the most hotly contested ideas in evolutionary biology. Here we propose a simple evolutionary model of behavior and show that what appears to be group selection may, in fact, simply be the consequence of natural selection occurring in stochastic environments with reproductive risks that are correlated across individuals. Those individuals with highly correlated risks will appear to form “groups”, even if their actions are, in fact, totally autonomous, mindless, and, prior to selection, uniformly randomly distributed in the population. This framework implies that a separate theory of group selection is not strictly necessary to explain observed phenomena such as altruism and cooperation. At the same time, it shows that the notion of group selection does captures a unique aspect of evolution—selection with correlated reproductive risk–that may be sufficiently widespread to warrant a separate term for the phenomenon. PMID:25353167

  20. Wear Behavior of a Novel Aluminum-Based Hybrid Composite

    NASA Astrophysics Data System (ADS)

    Show, Bijay Kumar; Mondal, Dipak Kumar; Maity, Joydeep

    2014-02-01

    In the current research, the dry sliding wear behaviors of 6351 Al alloy and its composite with hybrid reinforcement ( ex situ SiC and in situ Al4SiC4) were investigated at low sliding speed (1 m s-1) against a hardened EN 31 disk at different loads. The wear mechanism involved adhesion and microcutting-abrasion at lower load. On the other hand, at higher load, abrasive wear involving microcutting and microplowing along with adherent oxide formation was observed. Initially, under higher load, the abrasive wear mechanism caused rapid wear loss up to a certain sliding distance. Afterward, by virtue of frictional heat generation and associated temperature rise, an adherent oxide layer was developed at the pin surface which drastically reduced the wear loss. The overall wear rate increased with load in alloy as well as in composite. Moreover, the overall wear rate of the composite was found lower than that of the 6351 Al alloy at all applied loads. The ex situ SiC particles were found to resist abrasive wear, while, in situ Al4SiC4 particles offered resistance to adhesive wear. Accordingly, the 6351 Al (SiC + Al4SiC4) hybrid composite exhibited superior wear resistance relative to the 6351 Al alloy.

  1. Psychological Adaptation to Extreme Environments: Effects of Team Composition on Individual Adaptation

    NASA Technical Reports Server (NTRS)

    Wood, J.; Hysong, S. J.; Lugg, D. J.; Harm, D. L.

    1999-01-01

    This study is part of an ongoing program of research examining the psychological effects of isolation and confinement on individual adaptation, productivity and group relations in Antarctic winter personnel. This environment is used as an analogue for long-duration space mission scenarios, such as a space station sojourn, or a mission to Mars. Earlier results from this and other environments have demonstrated that: (1) most changes in psychological well-being are event-related and of relatively short duration; and (2) the greatest problem facing most individuals is interpersonal conflict. Content analysis of responses to open-ended questions has identified the numerous enjoyable aspects of Antarctic living, and confirmed that many of the problems reported were interpersonal in nature, and that problems varied significantly by station. Current work is exploring the effects of team assignment on the self-reported psychological changes and self-evaluations of members of isolated teams. This work includes identifying the dimensions by which subjects determine how well they are functioning. These dimensions (e.g., work, social life, internal emotional state) appear to play an important role in how subjects evaluate many aspects of life in isolation.

  2. Information systems for durability and damage behavior of composites

    NASA Astrophysics Data System (ADS)

    Turkgenc, Ozgur

    Damage tolerance, damage resistance and durability assessments of airborne composite structures are essential parts of their certification procedure. The certification procedure, in general, usually requires lengthy experimental efforts although much research has been conducted to understand the behavior of polymer matrix composites under service conditions. A fair amount of data is available together with a number of analytical models in these areas of research. However, because of the vast number of parameters involved, a generic model is rather difficult to develop. The ultimate goal of this study is the identification of design parameters to be used in the development of information system tools that can help engineers synthesize different sets of data efficiently. In the information system for damage behavior, all parameters that have been studied so far are provided for the user to choose as input. The output contains design parameters such as compression strength after impact, dent depth and damage area as well as literature references, raw data, tables, and plots. The information system is constituted in a relational database environment and tools from expert system technology are incorporated so that low confidence input can be captured and flexibility can be maintained in similarity assessments. With this system it is also possible to conduct parametric studies in order to determine the effect of each design parameter or a combination of parameters on the damage behavior. These objectives have been achieved by developing custom user interfaces using various programming languages. Case examples are included to demonstrate practical uses of the information system for both data retrieval and similarity studies. A similar system has been developed for fatigue design of composites. To achieve this goal, design parameters have been identified as well as the values these parameters can take. Results of the parameter identification study have been used to create

  3. Study of thermal and fire behavior of wood fiber/thermoplastic composite materials

    NASA Astrophysics Data System (ADS)

    Oladipo, Adedejo Bukola

    The fire safety characteristics of wood fiber/thermoplastic composite materials were investigated in this study. Composites comprising wood fiber fillers and polymeric binders are known to offer many advantages such as good strength to weight ratio, ease of manufacture, low cost, and the possibility for recycling. In spite of these advantages however, the fire safety question of plastic-based materials is an important one since they can, under certain conditions, drip or run, under fire, thereby potentially spreading fire from one location to the other. It is important therefore to understand the fire behavior of such a composite if the advantages it offers are to be fully utilized. To this end, numerical and experimental studies of opposed flow flame spread over the composite were conducted with emphasis on the influences of gravity, material thermal property variations, and finite-rate chemistry on the rate of spread. The thermal properties of the composite material, needed for opposed flame spread computations, were first determined using a combination of inverse heat conduction and non-linear parameter estimation procedures. The influences of wood fiber mass fraction and temperature on the effective thermal properties of the composite were established. The means for predicting the effective properties from those of the individual constituents were also examined and the results showed that the composite is close to being isotropic. The experimental and numerical methods used to determine the thermal properties of the composite were also adapted for the investigation of various proprietary automobile sound blanket materials to assess their effectiveness as thermal barriers separating the engine compartment from the passenger cabin. The results of opposed flame spread study over the composite suggests that, for opposed flow velocities lower than about 245 cm/s, finite rate chemistry will dominate the spread process when the oxygen mass fraction is 70% or less

  4. The behavior of bonded doubler splices for composite sandwich panels

    NASA Technical Reports Server (NTRS)

    Zeller, T. A.; Weisahaar, T. A.

    1980-01-01

    The results of an investigation into the behavior of adhesively bonded doubler splices of two composite material sandwich panels are presented. The splices are studied from three approaches: analytical; numerical (finite elements); and experimental. Several parameters that characterize the splice are developed to determine their influence upon joint strength. These parameters are: doubler overlap length; core stiffness; laminate bending stiffness; the size of the gap between the spliced sandwich panels; and room and elevated temperatures. Similarities and contrasts between these splices and the physically similar single and double lap joints are discussed. The results of this investigation suggest several possible approaches to improving the strength of the sandwich splices.

  5. Brainstem correlates of behavioral and compositional preferences of musical harmony.

    PubMed

    Bidelman, Gavin M; Krishnan, Ananthanarayan

    2011-03-30

    Certain chords are preferred by listeners behaviorally and also occur with higher regularity in musical composition. Event-related potentials index the perceived consonance (i.e., pleasantness) of musical pitch relationships providing a cortical neural correlate for such behavioral preferences. Here, we show correlates of these harmonic preferences exist at subcortical stages of audition. Brainstem frequency-following responses were measured in response to four prototypical musical triads. Pitch salience computed from frequency-following responses correctly predicted the ordering of triadic harmony stipulated by music theory (i.e., major >minor >diminished >augmented). Moreover, neural response magnitudes showed high correspondence with listeners' perceptual ratings of the same chords. Results suggest that preattentive stages of pitch processing may contribute to perceptual judgments of musical harmony. PMID:21358554

  6. Brainstem correlates of behavioral and compositional preferences of musical harmony

    PubMed Central

    Bidelman, Gavin M.; Krishnan, Ananthanarayan

    2011-01-01

    Certain chords are preferred by listeners behaviorally and also occur with higher regularity in musical composition. Event-related potentials index the perceived consonance (i.e., pleasantness) of musical pitch relationships providing a cortical neural correlate for such behavioral preferences. Here, we demonstrate correlates of these harmonic preferences exist at subcortical stages of audition. Brainstem frequency-following responses (FFRs) were measured in response to four prototypical musical triads. Pitch salience computed from FFRs correctly predicted the ordering of triadic harmony stipulated by music theory (i.e., major > minor ≫ diminished > augmented). Moreover, neural response magnitudes showed high correspondence with listeners’ perceptual ratings of the same chords. Results suggest that pre-attentive stages of pitch processing may contribute to perceptual judgments of musical harmony. PMID:21358554

  7. Thermal Degradation and Combustion Behavior of Polypropylene/MWCNT Composites

    NASA Astrophysics Data System (ADS)

    Zaikov, G. E.; Rakhimkulov, A. D.; Lomakin, S. M.; Dubnikova, I. L.; Shchegolikhin, A. N.; Davidov, E. Ya.

    2010-06-01

    Studies of thermal and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by means of melt intercalation are discussed. The sets of the data acquired with the aid of non-isothermal TG experiments have been treated by the model kinetic analysis. The thermal-oxidative degradation behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy. The results of cone calorimetric tests lead to the conclusion that char formation plays a key role in the mechanism of flame retardation for nanocomposites. This could be explained by the specific antioxidant properties and high thermal conductivity of MWCNT which determine high-performance carbonization during thermal degradation process. Comparative analysis of the flammability characteristics for PP-clay/MWCNT nanocomposites was provided in order to emphasize the specific behavior of the nanocomposites under high-temperature tests.

  8. Consequences of Serotonin Transporter Genotype and Early Adversity on Behavioral Profile – Pathology or Adaptation?

    PubMed Central

    Heiming, Rebecca S.; Sachser, Norbert

    2010-01-01

    This review focuses on how behavioral profile is shaped by early adversity in individuals with varying serotonin transporter (5-HTT) genotype. In a recent study on 5-HTT knockout mice Heiming et al. (2009) simulated a ‘dangerous environment‘ by confronting pregnant and lactating females with odor cues of unfamiliar males, indicating the risk of infant killing. Growing up in a dangerous environment induced increased anxiety-related behavior and decreased exploratory locomotion in the offspring, the effects being most pronounced in mice lacking 5-HTT expression. We argue that these alterations in behavioral profile represent adaptive maternal effects that help the individuals to cope with adversity. In principle, such effects of adversity on behavioral profile should not automatically be regarded as pathological. Rather and in accordance with modern evolutionary theory they may represent adaptations, although individuals with 5-HTT genotype induced susceptibility to adversity may be at risk of developing pathologies. PMID:21151780

  9. Adaptation of community health worker-delivered behavioral activation for torture survivors in Kurdistan, Iraq

    PubMed Central

    Magidson, J. F.; Lejuez, C. W.; Kamal, T.; Blevins, E. J.; Murray, L. K.; Bass, J. K.; Bolton, P.; Pagoto, S.

    2016-01-01

    Background Growing evidence supports the use of Western therapies for the treatment of depression, trauma, and stress delivered by community health workers (CHWs) in conflict-affected, resource-limited countries. A recent randomized controlled trial (Bolton et al. 2014a) supported the efficacy of two CHW-delivered interventions, cognitive processing therapy (CPT) and brief behavioral activation treatment for depression (BATD), for reducing depressive symptoms and functional impairment among torture survivors in the Kurdish region of Iraq. Methods This study describes the adaptation of the CHW-delivered BATD approach delivered in this trial (Bolton et al.2014a), informed by the Assessment–Decision–Administration-Production–Topical experts–Integration–Training–Testing (ADAPT–ITT) framework for intervention adaptation (Wingood & DiClemente, 2008). Cultural modifications, adaptations for low-literacy, and tailored training and supervision for non-specialist CHWs are presented, along with two clinical case examples to illustrate delivery of the adapted intervention in this setting. Results Eleven CHWs, a study psychiatrist, and the CHW clinical supervisor were trained in BATD. The adaptation process followed the ADAPT–ITT framework and was iterative with significant input from the on-site supervisor and CHWs. Modifications were made to fit Kurdish culture, including culturally relevant analogies, use of stickers for behavior monitoring, cultural modifications to behavioral contracts, and including telephone-delivered sessions to enhance feasibility. Conclusions BATD was delivered by CHWs in a resource-poor, conflict-affected area in Kurdistan, Iraq, with some important modifications, including low-literacy adaptations, increased cultural relevancy of clinical materials, and tailored training and supervision for CHWs. Barriers to implementation, lessons learned, and recommendations for future efforts to adapt behavioral therapies for resource

  10. Effect of light-curing unit and adhesive system on marginal adaptation of class v composite restorations.

    PubMed

    Maia-Casseli, Denise S; Faria-e-Silva, André L; Cavalcanti, Andréa N; Romani, Eliene A O N; Martins, Luis R M

    2012-01-01

    The aim of this study was to evaluate the effect of light-curing units (LED or halogen) on the marginal adaptation of composite restorations performed with etch-and-rinse and self-etching adhesive. Class V cavities were prepared on bovine teeth with the gingival margin on dentin and the incisal margin on enamel. The cavities were restored with a micro-hybrid resin composite using an etch-and-rinse (Single Bond 2--SB) or a self-etching adhesive (Clearfil SE Bond--CL). The light-activations were performed using halogen lamp (Optilux 501--QTH) or second-generation light-emitting diode (Radii-Cal--LED) (n = 10). After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed under scanning electronic microscopy with 500x of magnification. The greatest gap width at each margin was recorded. Data were submitted to Mann-Whitney and Wilcoxon tests (a = 0.05). SB and CL showed similar behavior of enamel margins when the light-activations were performed with QTH. The same was observed for dentin margins with LED. When the LED was used, higher gap measurements at enamel margins were observed with CL, while higher gap values in dentin were observed for SB within QTH. No significant difference between substrates was found when CL was used. However, SB had significantly higher gap measurements in dentin. The light-curing unit seems to affect the marginal adaptation of resin composite restorations. However this effect was dependent on the adhesive and the location of the margin. PMID:22928384

  11. The Role of Adaptive Behavior in Autism Spectrum Disorders: Implications for Functional Outcome

    ERIC Educational Resources Information Center

    Kanne, Stephen M.; Gerber, Andrew J.; Quirmbach, Linda M.; Sparrow, Sara S.; Cicchetti, Domenic V.; Saulnier, Celine A.

    2011-01-01

    The relationship between adaptive functioning and autism symptomatology was examined in 1,089 verbal youths with ASD examining results on Vineland-II, IQ, and measures of ASD severity. Strong positive relationships were found between Vineland subscales and IQ. Vineland Composite was negatively associated with age. IQ accounted a significant amount…

  12. Studying the Neural Basis of Adaptive Locomotor Behavior in Insects

    PubMed Central

    Gruhn, Matthias; Rosenbaum, Philipp; Bollhagen, Hans-Peter; Bueschges, Ansgar

    2011-01-01

    Studying the neural basis of walking behavior, one often faces the problem that it is hard to separate the neuronally produced stepping output from those leg movements that result from passive forces and interactions with other legs through the common contact with the substrate. If we want to understand, which part of a given movement is produced by nervous system motor output, kinematic analysis of stepping movements, therefore, needs to be complemented with electrophysiological recordings of motor activity. The recording of neuronal or muscular activity in a behaving animal is often limited by the electrophysiological equipment which can constrain the animal in its ability to move with as many degrees of freedom as possible. This can either be avoided by using implantable electrodes and then having the animal move on a long tether (i.e. Clarac et al., 1987; Duch & Pflüger, 1995; Böhm et al., 1997; Gruhn & Rathmayer, 2002) or by transmitting the data using telemetric devices (Kutsch et al, 1993; Fischer et al., 1996; Tsuchida et al. 2004; Hama et al., 2007; Wang et al., 2008). Both of these elegant methods, which are successfully used in larger arthropods, often prove difficult to apply in smaller walking insects which either easily get entangled in the long tether or are hindered by the weight of the telemetric device and its batteries. In addition, in all these cases, it is still impossible to distinguish between the purely neuronal basis of locomotion and the effects exerted by mechanical coupling between the walking legs through the substrate. One solution for this problem is to conduct the experiments in a tethered animal that is free to walk in place and that is locally suspended, for example over a slippery surface, which effectively removes most ground contact mechanics. This has been used to study escape responses (Camhi and Nolen, 1981; Camhi and Levy, 1988), turning (Tryba and Ritzman, 2000a,b; Gruhn et al., 2009a), backward walking (Graham and

  13. Interpreting problematic behavior: systematic compensatory adaptations as emergent phenomena in autism.

    PubMed

    Damico, Jack S; Nelson, Ryan L

    2005-01-01

    Based upon an emergent account of pragmatic ability and disability, this article provides theoretical and empirical support for a conceptually deeper understanding of some systematic behaviors that have served as diagnostic indices in communicatively impaired populations. Specifically, by employing conversation analysis, several examples of problematic behaviors in autism are analysed as a specific type of compensatory adaptation. Theoretical and clinical implications are discussed. PMID:16019784

  14. Evaluation of cervical marginal and internal adaptation using newer bulk fill composites: An in vitro study

    PubMed Central

    Agarwal, Rolly Shrivastav; Hiremath, Hemlatha; Agarwal, Jatin; Garg, Ashish

    2015-01-01

    Objective: To evaluate the cervical marginal and internal adaptation of posterior bulk fill resin composites of different viscosities, before and after thermo-cycling (TMC). Materials and Methods: Eighty box-only class II cavities were prepared in 40 extracted human premolars with the distal proximal box beneath the enamel-cementum junction (CEJ). The teeth in the experimental groups were restored with bulk fill resin composite restorations (Gr. I- Sonic Fill, Gr. II- SDR, Gr. III- Tetric N Ceram Bulk Fill or a conventional composite designed for 2-mm increments (Gr. IV- Tetric N Flow along with Tetric N Ceram). Before and after thermal cycling, the gap-free marginal length was analyzed using SEM of epoxy resin replicas. After thermal cycling, specimens were cut longitudinally in order to investigate internal dentine adaptation by epoxy replicas under SEM (500 × magnification). Results: Statistical analysis was performed using the ANOVA and Tukey Post Hoc tests (P < 0.05). In enamel, high percentages of gap-free margins were initially identified for all the groups, which declined after thermal cycling. However, no significant differences were identified among any of the groups (P > 0.05). In dentine, bulk fill groups performed at par with the incremental placement; for both marginal and internal adaptation (P < 0.05), for all materials except Tetric N Ceram Bulk Fill. Conclusions: Viscosity of the bulk fill restorative material influenced the proportion of gap-free marginal interface and the internal adaptation in dentin. PMID:25657529

  15. Robust vibration suppression of an adaptive circular composite plate for satellite thrust vector control

    NASA Astrophysics Data System (ADS)

    Yan, Su; Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2008-03-01

    In this paper, a novel application of adaptive composite structures, a University of Hawaii at Manoa (UHM) smart composite platform, is developed for the Thrust Vector Control (TVC) of satellites. The device top plate of the UHM platform is an adaptive circular composite plate (ACCP) that utilizes integrated sensors/actuators and controllers to suppress low frequency vibrations during the thruster firing as well as to potentially isolate dynamic responses from the satellite structure bus. Since the disturbance due to the satellite thruster firing can be estimated, a combined strategy of an adaptive disturbance observer (DOB) and feed-forward control is proposed for vibration suppression of the ACCP with multi-sensors and multi-actuators. Meanwhile, the effects of the DOB cut-off frequency and the relative degree of the low-pass filter on the DOB performance are investigated. Simulations and experimental results show that higher relative degree of the low-pass filter with the required cut-off frequency will enhance the DOB performance for a high-order system control. Further, although the increase of the filter cut-off frequency can guarantee a sufficient stability margin, it may cause an undesirable increase of the control bandwidth. The effectiveness of the proposed adaptive DOB with feed-forward control strategy is verified through simulations and experiments using the ACCP system.

  16. Nonequilibrium material effects on the behavior of polymeric composite matrices and their related composites

    NASA Technical Reports Server (NTRS)

    Wilkes, G. L.

    1982-01-01

    The effects of physical aging on the material properties of some linear and network macromolecular glasses are discussed. The free volume concept is used to describe this behavior. The effect of physical aging on properties of some uniaxial graphite/fiber epoxy resin composites is investigated using stress relaxation in both tensile and flexural modes. The matrix polymers used were resins both of which are based on a 4,4-methylenedianiline derivative of epichlorohydrin with diamino diphenyl sulfone (DDS) as the curing agent. The matrix resin, as used in the practical application in composites, not fully cured and the glass transition of the network was dependent on the curing schedule. The physical aging of the bulk crosslinked epoxy was found to depend on the annealing temperature, and the T sub g of the resin. The physical aging of the composite, monitored by the stress relaxation method, was found to be dependent on the testing direction.

  17. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    NASA Astrophysics Data System (ADS)

    Palkovic, Steven D.; Moeini, Sina; Yip, Sidney; Büyüköztürk, Oral

    2015-07-01

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  18. Fatigue behavior and recommended design rules for an automotive composite

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; Ruggles, M.B.

    1998-11-01

    Fatigue curves (stress vs cycles to failure) were generated under a variety of conditions (temperatures, fluid environments, mean stresses, block loadings) for a candidate automotive structural composite. The results were used to (1) develop observations regarding basic fatigue behavioral characteristics and (2) establish fatigue design rules. The composite was a structural reaction injection-molded polyurethane reinforced with continuous strand, swirl-mat E-glass fibers. Tensile fatigue tests on specimens from a single plaque at {minus}40 F, room temperature, and 250 F provided the basic behavioral characteristics. It was found that when stress was normalized by the at-temperature ultimate tensile strength, the fatigue curves at the three temperatures collapsed into a single master curve. An assessment of the individual stress-strain loops throughout each test showed a progressive loss in stiffness and an increase in permanent strain, both of which are indicative of increasing damage. Fatigue tests on specimens from several plaques were used to develop a design fatigue curve, which was established by using a reduction factor of 20 on average cycles to failure. This factor assures that the stiffness loss during the design life is no greater than 10 percent. Fatigue reduction factors were established to account for various fluids. Reversed stress fatigue tests allowed a mean stress rule to be validated, and block loading tests were used to demonstrate the adequacy of Miner`s rule for cumulative fatigue damage.

  19. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    SciTech Connect

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral; Yip, Sidney

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  20. Neurodevelopmental Status and Adaptive Behaviors in Preschool Children with Chronic Kidney Disease

    ERIC Educational Resources Information Center

    Duquette, Peter J.; Hooper, Stephen R.; Icard, Phil F.; Hower, Sarah J.; Mamak, Eva G.; Wetherington, Crista E.; Gipson, Debbie S.

    2009-01-01

    This study examines the early neurodevelopmental function of infants and preschool children who have chronic kidney disease (CKD). Fifteen patients with CKD are compared to a healthy control group using the "Mullen Scales of Early Learning" (MSEL) and the "Vineland Adaptive Behavior Scale" (VABS). Multivariate analysis reveals significant…

  1. Future Time Perspective as a Predictor of Adolescents' Adaptive Behavior in School

    ERIC Educational Resources Information Center

    Carvalho, Renato Gil Gomes

    2015-01-01

    Future time perspective (FTP) has been associated with positive outcomes in adolescents' development across different contexts. However, the extent to which FTP influences adaptation needs additional understanding. In this study, we analysed the relationship between FTP and adolescents' behavior in school, as expressed in several indicators of…

  2. Adaptive Responses to Prochloraz Exposure That Alter Dose-Response and Time-Course Behaviors

    EPA Science Inventory

    Dose response and time-course (DRTC) are, along with exposure, the major determinants of health risk. Adaptive changes within exposed organisms in response to environmental stress are common, and alter DRTC behaviors to minimize the effects caused by stressors. In this project, ...

  3. A Systematic Review and Psychometric Evaluation of Adaptive Behavior Scales and Recommendations for Practice

    ERIC Educational Resources Information Center

    Floyd, Randy G.; Shands, Elizabeth I.; Alfonso, Vincent C.; Phillips, Jessica F.; Autry, Beth K.; Mosteller, Jessica A.; Skinner, Mary; Irby, Sarah

    2015-01-01

    Adaptive behavior scales are vital in assessing children and adolescents who experience a range of disabling conditions in school settings. This article presents the results of an evaluation of the design characteristics, norming, scale characteristics, reliability and validity evidence, and bias identification studies supporting 14…

  4. Effects of Age on the Adaptive Behavior of Institutionalized and Noninstitutionalized Individuals with Down Syndrome.

    ERIC Educational Resources Information Center

    Silverstein, A. B.; And Others

    1988-01-01

    Evidence of an association between Alzheimer disease and Down syndrome led to three studies on the effects of age on the adaptive behavior of over 400 Down syndrome individuals. One study found a decline in motor development competence among older (over 60 years) Down syndrome individuals when compared with other mentally retarded persons.…

  5. Adaptive Behavior and Cognitive Function of Adults with Down Syndrome: Modeling Change with Age.

    ERIC Educational Resources Information Center

    Hawkins, Barbara A.; Eklund, Susan J.; James, David R.; Foose, Alice K.

    2003-01-01

    Fifty-eight adults with Down syndrome were assessed longitudinally over 10 years for the purpose of modeling aging-related change in cognitive function and adaptive behavior. Findings provide further evidence of changes in performance with age and include selected effects for participants who completed the study and those lost to follow-up.…

  6. Incidence and Temporal Patterns of Adaptive Behavior Change in Adults with Mental Retardation.

    ERIC Educational Resources Information Center

    Zigman, Warren B.; Schupf, Nicole; Urv, Tiina; Zigman, April; Silverman, Wayne

    2002-01-01

    A study found cumulative decline in adaptive behavior and functional skills in 248 adults with Down syndrome increased from less than .04 at age 50, to .67 by 72, whereas decline for 398 adults with mental retardation increased from less than .02 at age 50 to .52 at 88. (Contains references.) (Author/CR)

  7. Assessment of Social Competence, Adaptive Behaviors, and Approaches to Learning with Young Children. Working Paper Series.

    ERIC Educational Resources Information Center

    Meisels, Samuel J.; Atkins-Burnett, Sally; Nicholson, Julie

    Prepared in support of the Early Childhood Longitudinal Study (ECLS), which will examine children's early school experiences beginning with kindergarten, this working paper focuses on research regarding the measurement of young children's social competence, adaptive behavior, and approaches to learning. The paper reviews the key variables and…

  8. Adaptive Behavior and Development of Infants and Toddlers with Williams Syndrome.

    PubMed

    Kirchner, Rebecca M; Martens, Marilee A; Andridge, Rebecca R

    2016-01-01

    Williams syndrome (WS) is a neurodevelopmental disorder that causes deficits in adaptive behavior, difficulties eating and sleeping, cognitive delays, and delayed development. Although researchers have conducted characterizations of children and adults with WS, less is known about young children with this disorder. This study characterizes the developmental and adaptive behavior features of 16 infants and toddlers with WS aged 3 months - 5 years. Data for this project was obtained from 2007 to 2014, and includes parent report data and standardized developmental testing. Thirty-one percent (31.3%) of parents reported that their infant/toddler with WS had sleeping problems and 58.3% reported feeding difficulties. Levels of adaptive behavior were in the Mildly Delayed range as measured by the Adaptive Behavior Assessment System, Second Edition. Self-care skills such as feeding or dressing oneself were significantly weaker than skills needed to function in the community, such as recognizing his/her home or throwing away trash. The difficulty with self-care skills is hypothesized to be related to the reported difficulties with eating and sleeping. Motor skills were significantly lower than both cognitive and language skills on the Bayley Scales of Infant and Toddler Development, Third Edition. The current study highlights the need for early intervention in these young children across all areas of development, particularly in self-care skills. PMID:27199832

  9. Longitudinal Changes in Adaptive Behavior in Adults with Down Syndrome: Interim Findings from a Longitudinal Study.

    ERIC Educational Resources Information Center

    Prasher, V. P.; Chung, Man Cheung; Haque, M. S.

    1998-01-01

    A study examined underlying factors for age-related decline in adaptive behavior in 128 adults with trisomy 21 over a three-year period. Presence of dementia was the only determining factor, although the difference in trend over time as compared to subjects without dementia was not significant. (Author/CR)

  10. An ICF-CY-Based Content Analysis of the Vineland Adaptive Behavior Scales-II

    ERIC Educational Resources Information Center

    Gleason, Kara; Coster, Wendy

    2012-01-01

    Background: The International Classification of Functioning, Disability and Health (ICF), and its version for children and youth (ICF-CY), has been increasingly adopted as a system to describe function and disability. A content analysis of the Vineland Adaptive Behavior Scales-II (VABS-II) was conducted to examine congruence with the functioning…

  11. Intelligence, Parental Depression, and Behavior Adaptability in Deaf Children Being Considered for Cochlear Implantation

    ERIC Educational Resources Information Center

    Kushalnagar, Poorna; Krull, Kevin; Hannay, Julia; Mehta, Paras; Caudle, Susan; Oghalai, John

    2007-01-01

    Cognitive ability and behavioral adaptability are distinct, yet related, constructs that can impact childhood development. Both are often reduced in deaf children of hearing parents who do not provide sufficient language and communication access. Additionally, parental depression is commonly observed due to parent-child communication difficulties…

  12. Cross-Cultural Adaptation of Internationally Adopted Chinese Children: Communication and Symbolic Behavior Development

    ERIC Educational Resources Information Center

    Hwa-Froelich, Deborah A.; Matsuoh, Hisako

    2008-01-01

    Adaptation of internationally adopted children to another culture and language has not been studied extensively. This study followed four infant girls from China during the 1st year postadoption, measuring vocabulary, gestural, social, communication, and symbolic behavior development each month. The children were also tested at 2 and 3 years…

  13. Psychometric Properties of the Portuguese Version of the Adaptive Behavior Scale

    ERIC Educational Resources Information Center

    Santos, Sofia; Morato, Pedro; Luckasson, Ruth

    2014-01-01

    The adaptive behavior construct has gained prominent attention in human services over the last several years in Portugal, and its measurement has become an integral part of the assessment of populations with intellectual disability. In Portugal, diagnosis remains exclusively based on IQ measures, although some attention recently has been given to…

  14. The Assessment of Minority Students: Are Adaptive Behavior Scales the Answer?

    ERIC Educational Resources Information Center

    Baca, Leonard; Cervantes, Hermes

    1978-01-01

    The use of adaptive behavior scales in the assessment of minority children was discussed. Positive and negative characteristics of the scales developed by Mercer and Lambert were identified and discussed. Recommendations included cautions for the use of such scales in the evaluation of culturally different minority children. (Author)

  15. Studying the Genetics of Behavior and Evolution by Adaptation and Natural Selection.

    ERIC Educational Resources Information Center

    Silverman, Jules

    1998-01-01

    Provides an exercise designed to give students an appreciation for the genetic basis of behavior. Employs the phenomenon of glucose aversion as an example of evolution by mutation and accelerated natural selection, thereby revealing one of the ways in which organisms adapt to human interference. (DDR)

  16. Nonsocial Play Patterns of Young Children with Communication Disorders: Implications for Behavioral Adaptation

    ERIC Educational Resources Information Center

    Guralnick, Michael J.; Hammond, Mary A.; Connor, Robert T.

    2006-01-01

    It has been well established that young children with communication disorders (CD) have considerable difficulties interacting socially with peers in free-play settings. The central purpose of this study was to determine whether behavioral adaptations of children with CD could contribute to their peer interaction problems. To accomplish this, the…

  17. Adaptive Behavior and Development of Infants and Toddlers with Williams Syndrome

    PubMed Central

    Kirchner, Rebecca M.; Martens, Marilee A.; Andridge, Rebecca R.

    2016-01-01

    Williams syndrome (WS) is a neurodevelopmental disorder that causes deficits in adaptive behavior, difficulties eating and sleeping, cognitive delays, and delayed development. Although researchers have conducted characterizations of children and adults with WS, less is known about young children with this disorder. This study characterizes the developmental and adaptive behavior features of 16 infants and toddlers with WS aged 3 months – 5 years. Data for this project was obtained from 2007 to 2014, and includes parent report data and standardized developmental testing. Thirty-one percent (31.3%) of parents reported that their infant/toddler with WS had sleeping problems and 58.3% reported feeding difficulties. Levels of adaptive behavior were in the Mildly Delayed range as measured by the Adaptive Behavior Assessment System, Second Edition. Self-care skills such as feeding or dressing oneself were significantly weaker than skills needed to function in the community, such as recognizing his/her home or throwing away trash. The difficulty with self-care skills is hypothesized to be related to the reported difficulties with eating and sleeping. Motor skills were significantly lower than both cognitive and language skills on the Bayley Scales of Infant and Toddler Development, Third Edition. The current study highlights the need for early intervention in these young children across all areas of development, particularly in self-care skills. PMID:27199832

  18. The Two Faces of Adolescents' Success with Peers: Adolescent Popularity, Social Adaptation, and Deviant Behavior

    ERIC Educational Resources Information Center

    Allen, Joseph P.; Porter, Maryfrances R.; McFarland, F. Christy; Marsh, Penny; McElhaney, Kathleen Boykin

    2005-01-01

    This study assessed the hypothesis that popularity in adolescence takes on a twofold role, marking high levels of concurrent adaptation but predicting increases over time in both positive and negative behaviors sanctioned by peer norms. Multimethod, longitudinal data, on a diverse community sample of 185 adolescents (13 to 14 years), addressed…

  19. A Post-Genomic View of Behavioral Development and Adaptation to the Environment

    ERIC Educational Resources Information Center

    LaFreniere, Peter; MacDonald, Kevin

    2013-01-01

    Recent advances in molecular genetics and epigenetics are reviewed that have major implications for the bio-behavioral sciences and for understanding how organisms adapt to their environments at both phylogenetic and ontogenic levels. From a post-genomics perspective, the environment is as crucial as the DNA sequence for constructing the…

  20. Reliability of the AAMD Adaptive Behavior Scale-Public School Version.

    ERIC Educational Resources Information Center

    Mayfield, Kathy L.; And Others

    1984-01-01

    Investigated interrater reliability of the AAMD Adaptive Behavior Scale-Public School Version in a sample of 31 educable mentally handicapped children who were rated by their parents, special education teacher, classroom teacher, and an independent observer. Results showed ratings of the special education teacher were generally lower. (JAC)

  1. The Effects of Sociodrama on the Adaptive and Maladaptive Behaviors of Elementary School Boys.

    ERIC Educational Resources Information Center

    Bell, Steven Harvey

    The effects of sociodrama on the adaptive and maladaptive behaviors of elementary school boys were examined in three groups of six boys each. One group was used as a control for the Hawthorne effect; the second, as a control for teacher expectation effects and for changes as a function of involvement with a male counselor. In the experimental…

  2. Mothers' and Fathers' Parenting Styles and Associations with Toddlers' Externalizing, Internalizing, and Adaptive Behaviors

    ERIC Educational Resources Information Center

    Rinaldi, Christina M.; Howe, Nina

    2012-01-01

    The two primary objectives of the present study were to (a) investigate mothers' and fathers' reports of their own as well as their partner's parenting styles, and (b) assess how mothers' and fathers' parenting styles uniquely and jointly predicted toddlers' externalizing, internalizing, and adaptive behaviors. Fifty-nine mothers and fathers…

  3. Shuttle/Centaur G-prime composite adapters damage tolerance/repair test program

    NASA Technical Reports Server (NTRS)

    Sollars, Teresa A.

    1987-01-01

    The Space Shuttle/Centaur Composite Adapters Damage Tolerance/Repair Test program had as its goals the determination of probable and potentially critical defects or damages on the adapters' strength and stability, as well as the adequacy of repairs on significantly damaged areas and the generation of NDT data for the upgrading of acceptance criteria. Such rational accept/reject criteria and repair methods reduce both engineering liason costs and any unnecessary parts-scrapping. Successful 'damage tolerant' design ensures that degradations of strength and stability due to undetected defects or damage will not be catastrophic.

  4. Changes in taste neurons support the emergence of an adaptive behavior in cockroaches.

    PubMed

    Wada-Katsumata, Ayako; Silverman, Jules; Schal, Coby

    2013-05-24

    In response to the anthropogenic assault of toxic baits, populations of the German cockroach have rapidly evolved an adaptive behavioral aversion to glucose (a phagostimulant component of baits). We hypothesized that changes in the peripheral gustatory system are responsible for glucose aversion. In both wild-type and glucose-averse (GA) cockroaches, D-fructose and D-glucose stimulated sugar-gustatory receptor neurons (GRNs), whereas the deterrent caffeine stimulated bitter-GRNs. In contrast, in GA cockroaches, D-glucose also stimulated bitter-GRNs and suppressed the responses of sugar-GRNs. Thus, D-glucose is processed as both a phagostimulant and deterrent in GA cockroaches, and this newly acquired peripheral taste sensitivity underlies glucose aversion in multiple GA populations. The rapid emergence of this highly adaptive behavior underscores the plasticity of the sensory system to adapt to rapid environmental change. PMID:23704571

  5. The adaptive problems of female teenage refugees and their behavioral adjustment methods for coping

    PubMed Central

    Mhaidat, Fatin

    2016-01-01

    This study aimed at identifying the levels of adaptive problems among teenage female refugees in the government schools and explored the behavioral methods that were used to cope with the problems. The sample was composed of 220 Syrian female students (seventh to first secondary grades) enrolled at government schools within the Zarqa Directorate and who came to Jordan due to the war conditions in their home country. The study used the scale of adaptive problems that consists of four dimensions (depression, anger and hostility, low self-esteem, and feeling insecure) and a questionnaire of the behavioral adjustment methods for dealing with the problem of asylum. The results indicated that the Syrian teenage female refugees suffer a moderate degree of adaptation problems, and the positive adjustment methods they have used are more than the negatives. PMID:27175098

  6. Behavioral reactivity and addiction: the adaptation of behavioral response to reward opportunities.

    PubMed

    Trafton, Jodie A; Gifford, Elizabeth V

    2008-01-01

    Persons recovering from addiction must refrain from drug use even when the opportunity to use exists. Understanding how behavioral response to drug reward opportunities is modified is key to treating addiction. Most effective behavioral therapies encourage patients to increase reinforcement opportunities by engaging unidentified sources of nondrug reward. The authors integrate transdisciplinary research on the brain and behavioral effects of increasing reward availability to demonstrate one neurobiological mechanism by which behavioral therapies help patients abstain. Explicating neurobiological processes underlying psychotherapy provides predictions about the interaction between dopaminergic medications and therapy and the impact of individual differences in dopamine receptor expression on addiction vulnerability. PMID:18305282

  7. Longitudinal changes in cognitive and adaptive behavior in fragile X females: a prospective multicenter analysis.

    PubMed

    Fisch, G S; Carpenter, N; Holden, J J; Howard-Peebles, P N; Maddalena, A; Borghgraef, M; Steyaert, J; Fryns, J P

    1999-04-01

    In prospective studies of young, fragile X [fra(X)] males with the full mutation, cognitive abilities (IQ scores) and adaptive behavior levels (DQ scores) declined in most subjects tested. Little is known about longitudinal changes in IQ and DQ scores in young fra(X) females, although one earlier retrospective study showed declines in IQ scores in 8 of 11 subjects. To examine fra(X) females prospectively, we tested and retested 13 females with the full mutation, age 4 to 15 years. Nine were tested and retested in North America, and four were evaluated at the Catholic University in Leuven, Belgium. Cognitive abilities of North American females were measured using the Stanford-Binet 4th Edition. Adaptive behavior levels were ascertained from the Vineland Adaptive Behavior Scales. For Belgians, test-retest scores from the Wechsler Intelligence Scales for Children-Revised were used. Subjects were subsequently separated into two age cohorts: those tested initially before age 7 years and those tested initially after age 7 years. Compared with young males with the full mutation and of the same age, females expectedly display a wider range of IQ scores. Test-retest IQ scores showed statistically significant decreases (P < 0.03). Analysis of individual test-retest scores indicate that declines in eight females were statistically significant. Adaptive behavior scores were available only for North American females. Five of nine (55%) showed significant declines in DQ. Like young males with the full mutation, all females with the full mutation attained higher adaptive behavior levels than cognitive scores, i.e., DQ > IQ. PMID:10208167

  8. A control systems engineering approach for adaptive behavioral interventions: illustration with a fibromyalgia intervention.

    PubMed

    Deshpande, Sunil; Rivera, Daniel E; Younger, Jarred W; Nandola, Naresh N

    2014-09-01

    The term adaptive intervention has been used in behavioral medicine to describe operationalized and individually tailored strategies for prevention and treatment of chronic, relapsing disorders. Control systems engineering offers an attractive means for designing and implementing adaptive behavioral interventions that feature intensive measurement and frequent decision-making over time. This is illustrated in this paper for the case of a low-dose naltrexone treatment intervention for fibromyalgia. System identification methods from engineering are used to estimate dynamical models from daily diary reports completed by participants. These dynamical models then form part of a model predictive control algorithm which systematically decides on treatment dosages based on measurements obtained under real-life conditions involving noise, disturbances, and uncertainty. The effectiveness and implications of this approach for behavioral interventions (in general) and pain treatment (in particular) are demonstrated using informative simulations. PMID:25264467

  9. Tribological properties of adaptive phosphate composite coatings with addition of silver and molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Liu, Cancan; Chen, Lei; Zhou, Jiansong; Zhou, Huidi; Chen, Jianmin

    2014-05-01

    Adaptive phosphate composite coatings with addition of solid lubricants of molybdenum disulfide (MoS2) and silver (Ag) using aluminum chromium phosphate as the binder were fabricated on high-temperature steel. The tribological properties of phosphate composite coatings were evaluated from room temperature (RT) to 700 °C. The phase composition and microstructure were investigated according to the characterization by power X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The results show that the composite coating with the Ag/MoS2 mass ratio of 2:1 exhibits the stable and low friction coefficients from RT to 700 °C and relative low wear rates at all testing temperatures. The tribo-chemical reaction between Ag and MoS2 occurred in the rubbing process to form silver molybdates compounds lubricating film. The temperature-adaptive tribological properties were attributed to the formation of lubricating films composed of lubricants silver, MoS2 and silver molybdates phases on the worn surfaces of the composites coatings in a wide-temperature range.

  10. Treating Individuals with Intellectual Disabilities and Challenging Behaviors with Adapted Dialectical Behavior Therapy

    ERIC Educational Resources Information Center

    Brown, Julie F.; Brown, Milton Z.; Dibiasio, Paige

    2013-01-01

    Approximately one third of adults with intellectual and developmental disabilities have emotion dysregulation and challenging behaviors (CBs). Although research has not yet confirmed that existing treatments adequately reduce CBs in this population, dialectical behavior therapy (DBT) holds promise, as it has been shown to effectively reduce CBs in…

  11. Nature of Adaptive Behavior Deficits among Individuals Who Are Moderately-Severely Mentally Retarded in the West Bank.

    ERIC Educational Resources Information Center

    Baker, Ahmad M.

    1989-01-01

    Results of assessing the adaptive behavior of 200 individuals classified as mentally retarded and living in the West Bank region of the Middle East suggest that the nature and development of adaptive behavior of the mentally retarded in Third World areas may not conform to expected trends. (Author/DB)

  12. Adaptive Behavior in Childhood as an Antecedent of Psychological Functioning in Early Middle Age: Linkage via Career Orientation

    ERIC Educational Resources Information Center

    Pulkkinen, Lea; Feldt, Taru; Kokko, Katja

    2006-01-01

    The main aim of the study was to investigate the link between child and adolescent adaptive behavior and adult psychological functioning, and the role of career orientation in this linkage. This was based on a Finnish longitudinal study, where data at ages 8, 14, and 42 were available for 118 females and 115 males. Adaptive behavior, indicated by…

  13. Longitudinal Changes in Cognitive and Adaptive Behavior Scores in Children and Adolescents with the Fragile X Mutation or Autism.

    ERIC Educational Resources Information Center

    Fisch, Gene S.; Simensen, Richard J.; Schroer, R. J.

    2002-01-01

    Comparison of children and adolescents with Fragile X Syndrome (n=18) or autism (n=18) for changes in cognitive ability and adaptive behavior over 9 years found steeper decreases in IQ scores among Fragile X subjects with older autistic subjects autism exhibiting stable test-retest scores. Comparative declines in adaptive behavior scores were…

  14. Adaptive Behavior Ratings Correlate with Symptomatology and IQ among Individuals with High-Functioning Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kenworthy, Lauren; Case, Laura; Harms, Madeline B.; Martin, Alex; Wallace, Gregory L.

    2010-01-01

    Caregiver report on the Adaptive Behavior Assessment System-II (ABAS) for 40 high-functioning individuals with Autism Spectrum Disorders (ASD) and 30 typically developing (TD) individuals matched for age, IQ, and sex ratio revealed global adaptive behavior deficits in ASD, with social skills impairments particularly prominent. Within the ASD…

  15. Causes of Age-Related Decline in Adaptive Behavior of Adults with Down Syndrome: Differential Diagnoses of Dementia.

    ERIC Educational Resources Information Center

    Prasher, V. P.; Chung, Man Cheung

    1996-01-01

    A study was conducted of 201 adults with Down's syndrome to investigate the differential causes of decline in adaptive behavior. Results indicated that aging, dementia, and severity of mental retardation were significant factors, while absence of a medical illness predicted a higher level of adaptive behavior. (CR)

  16. Increasing Adaptive Behavior Skill Deficits from Childhood to Adolescence in Autism Spectrum Disorder: Role of Executive Function

    ERIC Educational Resources Information Center

    Pugliese, Cara E.; Anthony, Laura; Strang, John F.; Dudley, Katerina; Wallace, Gregory L.; Kenworthy, Lauren

    2015-01-01

    Almost half of all children with autism spectrum disorder have average cognitive abilities, yet outcome remains poor. Because outcome in HFASD is more related to adaptive behavior skills than cognitive level it is important to identify predictors of adaptive behavior. This study examines cognitive and demographic factors related to adaptive…

  17. A Self-Adaptive Behavior-Aware Recruitment Scheme for Participatory Sensing.

    PubMed

    Zeng, Yuanyuan; Li, Deshi

    2015-01-01

    Participatory sensing services utilizing the abundant social participants with sensor-enabled handheld smart device resources are gaining high interest nowadays. One of the challenges faced is the recruitment of participants by fully utilizing their daily activity behavior with self-adaptiveness toward the realistic application scenarios. In the paper, we propose a self-adaptive behavior-aware recruitment scheme for participatory sensing. People are assumed to join the sensing tasks along with their daily activity without pre-defined ground truth or any instructions. The scheme is proposed to model the tempo-spatial behavior and data quality rating to select participants for participatory sensing campaign. Based on this, the recruitment is formulated as a linear programming problem by considering tempo-spatial coverage, data quality, and budget. The scheme enables one to check and adjust the recruitment strategy adaptively according to application scenarios. The evaluations show that our scheme provides efficient sensing performance as stability, low-cost, tempo-spatial correlation and self-adaptiveness. PMID:26389910

  18. A Self-Adaptive Behavior-Aware Recruitment Scheme for Participatory Sensing

    PubMed Central

    Zeng, Yuanyuan; Li, Deshi

    2015-01-01

    Participatory sensing services utilizing the abundant social participants with sensor-enabled handheld smart device resources are gaining high interest nowadays. One of the challenges faced is the recruitment of participants by fully utilizing their daily activity behavior with self-adaptiveness toward the realistic application scenarios. In the paper, we propose a self-adaptive behavior-aware recruitment scheme for participatory sensing. People are assumed to join the sensing tasks along with their daily activity without pre-defined ground truth or any instructions. The scheme is proposed to model the tempo-spatial behavior and data quality rating to select participants for participatory sensing campaign. Based on this, the recruitment is formulated as a linear programming problem by considering tempo-spatial coverage, data quality, and budget. The scheme enables one to check and adjust the recruitment strategy adaptively according to application scenarios. The evaluations show that our scheme provides efficient sensing performance as stability, low-cost, tempo-spatial correlation and self-adaptiveness. PMID:26389910

  19. High temperature fatigue behavior of tungsten copper composites

    NASA Technical Reports Server (NTRS)

    Verrilli, M. J.; Kim, Y.-S.; Gabb, T. P.

    1990-01-01

    The present study investigates the high-temperature fatigue behavior of a 9-v/o tungsten fiber-reinforced copper matrix composite. Load-controlled isothermal fatigue at 260 and 560 C and thermomechanical fatigue (TMF) experiments, both in-phase and out-of-phase between 260 and 560 C, were performed. The stress-strain response under all conditions displayed considerable inelasticity. Strain ratchetting was observed during all the fatigue experiments. For the isothermal fatigue and in-phase TMF tests, the ratchetting was always in a tensile direction, continuing until failure. The ratchetting during the out-of-phase TMF test shifted from a tensile to a compressive direction. For all cases, the fatigue lives were found to be controlled by the damage of the copper matrix. On a stress basis, TMF loading substantially reduced lives relative to isothermal cycling.

  20. Fracture behavior of unidirectional boron/aluminum composite laminates

    NASA Technical Reports Server (NTRS)

    Jones, F. W.; Goree, J. G.

    1983-01-01

    An experimental investigation of the fracture behavior of unidirectional boron/aluminum composite laminates was conducted in order to verify the results of mathematical models. These models predict the fiber stresses and displacements and the amount of damage growth in a center-notched lamina as a function of the applied remote stress and the matrix and fiber material properties. A brittle lacquer coating was used to detect the yielding in the matrix while X-ray techniques were used to determine the number of broken fibers in the laminate. The notched strengths and the amounts of damage found in the specimens agreed well with those predicted by the models. It was shown that for thin laminates the amount of damage and the fiber displacements do not depend strongly on the number of plies for a given notch width.

  1. Positional behavior and limb bone adaptations in red howling monkeys (Alouatta seniculus).

    PubMed

    Schön Ybarra, M A; Schön, M A

    1987-01-01

    Morphological adaptations to climbing (a scansorial mode of quadrupedal, arboreal locomotion practised on twigs and small branches) are identified by relating anatomical details of limb bones to a sample of 6,136 instantaneous observational recordings on the positional behavior and support uses of 20 different free-ranging, adult red howlers. Our findings are used to infer the original habitat in which proto-red howlers may have acquired such adaptations and to hypothesize that climbing and its related anatomy are a primitive condition for anthropoids. PMID:3454342

  2. Creep behavior of abaca fibre reinforced composite material

    SciTech Connect

    Tobias, B.C.; Lieng, V.T.

    1996-12-31

    This study investigates the creep behavior of abaca fibre reinforced composite lamina. The optimum proportions of constituents and loading conditions, temperature and stresses, are investigated in terms of creep properties. Lamina with abaca fibre volume fractions of 60, 70 and 80 percent, embedded in polyester resin were fabricated. Creep tests in tension at three temperature levels 20{degrees}C, 100{degrees}C and 120{degrees}C and three constant stress levels of 0. 1 MPa, 0. 13 Mpa and 0. 198 MPa using a Dynamic Mechanical Analyzer (DMA) were performed. The creep curves show standard regions of an ideal creep curve such as primary and secondary creep stage. The results also show that the minimum creep rate of abaca fibre reinforced composite increases with the increase of temperature and applied stress. Plotting the minimum creep rate against stress, depicts the variations of stress exponents which vary from 1.6194 at 20{degrees}C to 0.4576 at 120{degrees}C.

  3. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  4. High temperature fatigue behavior of tungsten copper composites

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Kim, Yong-Suk; Gabb, Timothy P.

    1989-01-01

    The high temperature fatigue behavior of a 9 vol percent, tungsten fiber reinforced copper matrix composite was investigated. Load-controlled isothermal fatigue experiments at 260 and 560 C and thermomechanical fatigue (TMF) experiments, both in phase and out of phase between 260 and 560 C, were performed. The stress-strain response displayed considerable inelasticity under all conditions. Also, strain ratcheting was observed during all the fatigue experiments. For the isothermal fatigue and in-phase TMF tests, the ratcheting was always in a tensile direction, continuing until failure. The ratcheting during the out-of-phase TMF test shifted from a tensile direction to a compressive direction. This behavior was thought to be associated with the observed bulging and the extensive cracking of the out-of-phase specimen. For all cases, the fatigue lives were found to be controlled by damage to the copper matrix. Grain boundary cavitation was the dominant damage mechanism of the matrix. On a stress basis, TMF loading reduced lives substantially, relative to isothermal cycling. In-phase cycling resulted in the shortest lives, and isothermal fatigue at 260 C, the longest.

  5. Compositional, mechanical and hydrologic controls on fault slip behavior

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.

    comparing the frictional behavior of granular gouge and lithified fault rock as an analogue for cataclastic fault rocks at seismogenic depths, the lithification of fault rock is found to have a significant strengthening effect, however in phyllosilicate-rich rocks pre-existing foliation provides a weakening mechanism that offsets the strengthening due to lithification. This weakening depends on the intensity of foliation such that strongly foliated rocks, such as books of mica sheets, are significantly weaker than granular mica gouges. Very thick fault zones can exhibit a reduction in measured apparent friction, the magnitude of which may be related to the orientation of through-going R1 shears and internal structural complexity. Consistent velocity-strengthening behavior is observed for both lithified and granular phyllosilicate-rich samples despite the observation of slip localization features in microstructural analysis, suggesting that as an isolated parameter advanced lithification state of fault rock is also inadequate for allowing seismic slip nucleation. Collectively, the results of the experiments in this study have several important implications for fault slip behavior. Granular, unconsolidated phyllosilicate-rich gouges, such as those that are common at shallow depths in both subduction zones and strike-slip faults, will tend to be aseismic, a condition that may be related to their overall weakness. The transition from aseismic to seismic slip at the updip limit of the seismogenic zone should be driven by changes in pressure and temperature, due to the overall ambient conditions as well as inducing changes in the character of the fault material itself. These may include compositional changes and mechanical effects of the lithification process, such as consolidation and cementation. However, when tested as isolated variables, the dehydration of smectite, conversion of smectite to illite, and lithification of fault gouge were found to be insufficient in allowing

  6. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography

    PubMed Central

    TÜRK, Ayşe Gözde; SABUNCU, Metin; ÜNAL, Sena; ÖNAL, Banu; ULUSOY, Mübin

    2016-01-01

    ABSTRACT Objective The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT) to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Material and Methods Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany) after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs), allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply), and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (p<0.05), before and after cementation. Results Direct inlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442) and after (p=0.00001466) cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively). The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Conclusions Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after cementation

  7. Modeling the behavioral substrates of associate learning and memory - Adaptive neural models

    NASA Technical Reports Server (NTRS)

    Lee, Chuen-Chien

    1991-01-01

    Three adaptive single-neuron models based on neural analogies of behavior modification episodes are proposed, which attempt to bridge the gap between psychology and neurophysiology. The proposed models capture the predictive nature of Pavlovian conditioning, which is essential to the theory of adaptive/learning systems. The models learn to anticipate the occurrence of a conditioned response before the presence of a reinforcing stimulus when training is complete. Furthermore, each model can find the most nonredundant and earliest predictor of reinforcement. The behavior of the models accounts for several aspects of basic animal learning phenomena in Pavlovian conditioning beyond previous related models. Computer simulations show how well the models fit empirical data from various animal learning paradigms.

  8. Evolutionary Influences of Plastic Behavioral Responses Upon Environmental Challenges in an Adaptive Radiation.

    PubMed

    Foster, Susan A; Wund, Matthew A; Baker, John A

    2015-09-01

    At the end of the 19th century, the suggestion was made by several scientists, including J. M. Baldwin, that behavioral responses to environmental change could both rescue populations from extinction (Baldwin Effect) and influence the course of subsequent evolution. Here we provide the historical and theoretical background for this argument and offer evidence of the importance of these ideas for understanding how animals (and other organisms that exhibit behavior) will respond to the rapid environmental changes caused by human activity. We offer examples from long-term research on the evolution of behavioral and other phenotypes in the adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus), a radiation in which it is possible to infer ancestral patterns of behavioral plasticity relative to the post-glacial freshwater radiation in northwestern North America, and to use patterns of parallelism and contemporary evolution to understand adaptive causes of responses to environmental modification. Our work offers insights into the complexity of cognitive responses to environmental change, and into the importance of examining multiple aspects of the phenotype simultaneously, if we are to understand how behavioral shifts contribute to the persistence of populations and to subsequent evolution. We conclude by discussing the origins of apparent novelties induced by environmental shifts, and the importance of accounting for geographic variation within species if we are to accurately anticipate the effects of anthropogenic environmental modification on the persistence and evolution of animals. PMID:26163679

  9. Neurocognitive, adaptive, and behavioral functioning of individuals with Costello syndrome: a review.

    PubMed

    Axelrad, Marni E; Schwartz, David D; Katzenstein, Jennifer M; Hopkins, Elizabeth; Gripp, Karen W

    2011-05-15

    Costello syndrome is a rare rasopathy resulting from germline mutations of the proto-oncogene HRAS. Its phenotype includes severe failure-to-thrive, cardiac abnormalities, a predisposition to benign and malignant tumors, hypotonia, and developmental delay. Costello syndrome is associated with cognitive impairment, including intellectual functioning generally in the mild to moderate range of disability, commensurate adaptive functioning, and increased anxiety. Relative strengths have been found for nonverbal fluid reasoning (FR). Gender effects have been reported, with females showing better adaptive functioning across domains. Developmentally, nonverbal skills plateau in late childhood/early adolescence, whereas the rate of vocabulary acquisition may increase in adolescence into early adulthood. Here we review the literature assessing cognitive, adaptive, and behavioral functioning in Costello syndrome, and we provide data from an ongoing longitudinal study. Severity of cognitive impairment may depend upon the specific HRAS mutation, as three individuals with the p.G13C change showed average nonverbal FR skills and borderline-to-low average overall nonverbal IQ. Further, separation anxiety is more common in Costello syndrome than in the general population, affecting 39% of this cohort, and males are more often overly anxious than females. Interrelations between anxiety and cognitive and adaptive functioning were found, pointing to functional difficulties as a likely source of stress and anxiety. Taking into account data from animal models, cognitive and behavioral changes likely originate from abnormal differentiation of neuronal precursor cells, which result in structural and functional brain differences. PMID:21495179

  10. MPS II: adaptive behavior of patients and impact on the family system.

    PubMed

    Needham, Mary; Packman, Wendy; Rappoport, Maxwell; Quinn, Natasha; Cordova, Matthew; Macias, Sandra; Morgan, Cynthia; Packman, Seymour

    2014-06-01

    Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a chronic and progressive X-linked lysosomal disease that mainly affects males. It occurs in 1 in every 65,000 to 1 in 132,000 births. There are two distinct forms of the disease based on age of onset and clinical course: mild and severe. MPS II affects many organ systems including the nervous, cardiovascular, gastrointestinal and respiratory systems. Complications can include vision problems, progressive hearing loss, thickened and elastic skin, mental impairment, and enlarged liver and spleen. We herein focus on the adaptive behavior of individuals with MPS II, and the impact of MPS II on the family system. Outcomes from the Vineland-II Adaptive Behavior Scales showed that the MPS II patient sample experienced significantly lower functioning in communication, daily living skills, socialization, and motor skills compared to normative data. Patients with severe MPS II were found to have significantly lower adaptive functioning in all domains, as compared to those with mild MPS II. Length of time on ERT had no significant relationship to adaptive functioning. Results from the Peds QL Family Impact Module indicated that families of patients with MPS II experienced a lower overall health-related quality of life and overall lower family functioning (including lower emotional and cognitive functioning) than those with chronic illnesses residing in an inpatient setting. PMID:24190099

  11. Examining Specific Effects of Context on Adaptive Behavior and Achievement in Rural Africa: Six Case Studies from Southern Province, Zambia

    PubMed Central

    Reich, Jodi; Hart, Lesley; Thuma, Philip E.

    2011-01-01

    Generally accepted as universal, the construct of adaptive behavior differs in its manifestations across different cultures and settings. The Vineland-II was translated into Chitonga and adapted to the setting of rural Southern Province, Zambia. This version was administered to the parents/caregivers of 114 children (grades 3-7, mean age = 12.94, sd = 2.34). The relationships between these children's adaptive behavior, academic achievement and cognitive ability indicators are compared to those usually observed in US samples. Results reflect no association between adaptive behavior and cognitive ability indicators, but a strong relationship between high adaptive behavior and reading-related measures. Six case studies of children with high and low scores on the Vineland-II are presented to illustrate the possible factors affecting these outcomes. PMID:22391811

  12. The Association of Intelligence, Visual-Motor Functioning, and Personality Characteristics With Adaptive Behavior in Individuals With Williams Syndrome.

    PubMed

    Fu, Trista J; Lincoln, Alan J; Bellugi, Ursula; Searcy, Yvonne M

    2015-07-01

    Williams syndrome (WS) is associated with deficits in adaptive behavior and an uneven adaptive profile. This study investigated the association of intelligence, visual-motor functioning, and personality characteristics with the adaptive behavior in individuals with WS. One hundred individuals with WS and 25 individuals with developmental disabilities of other etiologies were included in this study. This study found that IQ and visual-motor functioning significantly predicted adaptive behavior in individuals of WS. Visual-motor functioning especially predicted the most amount of unique variance in overall adaptive behavior and contributed to the variance above and beyond that of IQ. Present study highlights the need for interventions that address visual-motor and motor functioning in individuals with WS. PMID:26161466

  13. Cell-intrinsic adaptation of lipid composition to local crowding drives social behaviour.

    PubMed

    Frechin, Mathieu; Stoeger, Thomas; Daetwyler, Stephan; Gehin, Charlotte; Battich, Nico; Damm, Eva-Maria; Stergiou, Lilli; Riezman, Howard; Pelkmans, Lucas

    2015-07-01

    Cells sense the context in which they grow to adapt their phenotype and allow multicellular patterning by mechanisms of autocrine and paracrine signalling. However, patterns also form in cell populations exposed to the same signalling molecules and substratum, which often correlate with specific features of the population context of single cells, such as local cell crowding. Here we reveal a cell-intrinsic molecular mechanism that allows multicellular patterning without requiring specific communication between cells. It acts by sensing the local crowding of a single cell through its ability to spread and activate focal adhesion kinase (FAK, also known as PTK2), resulting in adaptation of genes controlling membrane homeostasis. In cells experiencing low crowding, FAK suppresses transcription of the ABC transporter A1 (ABCA1) by inhibiting FOXO3 and TAL1. Agent-based computational modelling and experimental confirmation identified membrane-based signalling and feedback control as crucial for the emergence of population patterns of ABCA1 expression, which adapts membrane lipid composition to cell crowding and affects multiple signalling activities, including the suppression of ABCA1 expression itself. The simple design of this cell-intrinsic system and its broad impact on the signalling state of mammalian single cells suggests a fundamental role for a tunable membrane lipid composition in collective cell behaviour. PMID:26009010

  14. Effect of curing unit and adhesive system on marginal adaptation of composite restorations.

    PubMed

    Casselli, Denise Sa Maia; Faria-e-Silva, Andre Luis; Casselli, Henrique; Martins, Luis Roberto Marcondes

    2012-01-01

    This study sought to evaluate how a curing unit and adhesive system affected the marginal adaptation of resin composite restorations. Class V cavities were prepared in bovine teeth with a gingival margin in dentin and an incisal margin in enamel. The cavities were restored with a micro-hybrid resin composite using one of four adhesives: Single Bond 2, Prime & Bond NT, Clearfil SE Bond, Xeno IV. The light-activations were performed using a quartz-tungsten-halogen (QTH) lamp or a second-generation light-emitting diode (LED). Restorations were finished and polished and epoxy replicas were prepared. Marginal adaptation was analyzed by using scanning electronic microscopy (magnification 500X). The widest gaps in each margin were recorded, and data were submitted to Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests (α = 0.05). Differences between the adhesives were observed only when the dentin margins were evaluated: Clearfil SE Bond demonstrated better marginal adaptation than Prime & Bond NT or Single Bond 2 (which demonstrated the widest gaps in the dentin margin). The type of curing unit only affected the results for Xeno IV when the enamel margin was analyzed; the LED lamp promoted smaller gaps than the QTH lamp. PMID:23220321

  15. Hybrid Model Predictive Control for Sequential Decision Policies in Adaptive Behavioral Interventions

    PubMed Central

    Dong, Yuwen; Deshpande, Sunil; Rivera, Daniel E.; Downs, Danielle S.; Savage, Jennifer S.

    2015-01-01

    Control engineering offers a systematic and efficient method to optimize the effectiveness of individually tailored treatment and prevention policies known as adaptive or “just-in-time” behavioral interventions. The nature of these interventions requires assigning dosages at categorical levels, which has been addressed in prior work using Mixed Logical Dynamical (MLD)-based hybrid model predictive control (HMPC) schemes. However, certain requirements of adaptive behavioral interventions that involve sequential decision making have not been comprehensively explored in the literature. This paper presents an extension of the traditional MLD framework for HMPC by representing the requirements of sequential decision policies as mixed-integer linear constraints. This is accomplished with user-specified dosage sequence tables, manipulation of one input at a time, and a switching time strategy for assigning dosages at time intervals less frequent than the measurement sampling interval. A model developed for a gestational weight gain (GWG) intervention is used to illustrate the generation of these sequential decision policies and their effectiveness for implementing adaptive behavioral interventions involving multiple components. PMID:25635157

  16. Control of cognition and adaptive behavior by the GLP/G9a epigenetic suppressor complex

    PubMed Central

    Schaefer, Anne; Sampath, Srihari C.; Intrator, Adam; Min, Alice; Gertler, Tracy S.; Surmeier, D. James; Tarakhovsky, Alexander; Greengard, Paul

    2009-01-01

    SUMMARY The genetic basis of cognition and behavioral adaptation to the environment remains poorly understood. Here we demonstrate that the histone methyltransferase complex GLP/G9a controls cognition and adaptive responses in a region-specific fashion in the adult brain. Using conditional mutagenesis in mice, we show that postnatal, neuron-specific deficiency of GLP/G9a leads to de-repression of numerous non-neuronal and neuron progenitor genes in adult neurons. This transcriptional alteration is associated with complex behavioral abnormalities, including defects in learning, motivation and environmental adaptation. The behavioral changes triggered by GLP/G9a deficiency are similar to key symptoms of the human 9q34 mental retardation syndrome that is associated with structural alterations of the GLP gene. The likely causal role of GLP/G9a in mental retardation in mice and humans suggests a key role for the GLP/G9a controlled histone H3K9 di-methylation in regulation of brain function through maintenance of the transcriptional homeostasis in adult neurons. PMID:20005824

  17. The role of metabotropic glutamate receptors and cortical adaptation in habituation of odor-guided behavior

    PubMed Central

    Yadon, Carly A.; Wilson, Donald A.

    2005-01-01

    Decreases in behavioral investigation of novel stimuli over time may be mediated by a variety of factors including changes in attention, internal state, and motivation. Sensory cortical adaptation, a decrease in sensory cortical responsiveness over prolonged stimulation, may also play a role. In olfaction, metabotropic glutamate receptors on cortical afferent pre-synaptic terminals have been shown to underlie both cortical sensory adaptation and habituation of odor-evoked reflexes. The present experiment examined whether blockade of sensory cortical adaptation through bilateral infusion of the group III metabotropic glutamate receptor antagonist cyclopropyl-4-phosphonophenylglycine (CPPG) into the anterior piriform cortex could reduce habituation of a more complex odor-driven behavior such as investigation of a scented object or a conspecific. The results demonstrate that time spent investigating a scented jar, or a conspecific, decreases over the course of a continuous 10 minute trial. Acute infusion of CPPG bilaterally into the anterior piriform cortex significantly enhanced the time spent investigating the scented jar compared to investigation time in control rats, without affecting overall behavioral activity levels. Infusions into the brain outside of the piriform cortex were without effect. CPPG infusion into the piriform cortex also produced an enhancement of time spent investigating a conspecific, although this effect was not significant. PMID:16322361

  18. Longitudinal Effects of Adaptability on Behavior Problems and Maternal Depression in Families of Adolescents with Autism

    PubMed Central

    Baker, Jason K.; Seltzer, Marsha Mailick; Greenberg, Jan S.

    2014-01-01

    Research on families of individuals with autism has tended to focus on child-driven effects utilizing models of stress and coping. The current study used a family-systems perspective to examine whether family-level adaptability promoted beneficial outcomes for mothers and their adolescents with autism over time. Participants were 149 families of children diagnosed with autism who were between the ages of 10 and 22 years during the three-year period examined. Mothers reported on family adaptability, the mother-child relationship, their own depressive symptoms, and the behavior problems of their children at Wave 1, and these factors were used to predict maternal depression and child behavior problems three years later. Family-level adaptability predicted change in both maternal depression and child behavior problems over the study period, above and beyond the contribution of the dyadic mother-child relationship. These associations did not appear to depend upon the intellectual disability status of the individual with autism. Implications for autism, parent mental health, family systems theory, and for intervention with this population are discussed. PMID:21668120

  19. Compositional changes in RNA, DNA and proteins for bacterial adaptation to higher and lower temperatures.

    PubMed

    Nakashima, Hiroshi; Fukuchi, Satoshi; Nishikawa, Ken

    2003-04-01

    It is known that in thermophiles the G+C content of ribosomal RNA linearly correlates with growth temperature, while that of genomic DNA does not. Although the G+C contents (singlet) of the genomic DNAs of thermophiles and methophiles do not differ significantly, the dinucleotide (doublet) compositions of the two bacterial groups clearly do. The average amino acid compositions of proteins of the two groups are also distinct. Based on these facts, we here analyzed the DNA and protein compositions of various bacteria in terms of the optimal growth temperature (OGT). Regression analyses of the sequence data for thermophilic, mesophilic and psychrophilic bacteria revealed good linear relationships between OGT and the dinucleotide compositions of DNA, and between OGT and the amino acid compositions of proteins. Together with the above-mentioned linear relationship between ribosomal RNA and OGT, the DNA and protein compositions can be regarded as thermostability measures for RNA, DNA and proteins, covering a wide range of temperatures. Both the DNA and proteins of psychrophiles apparently exhibit characteristics diametrically opposite to those of thermophiles. The physicochemical parameters of dinucleotides suggested that supercoiling of DNA is relevant to its thermostability. Protein stability in thermophiles is realized primarily through global changes that increase charged residues (i.e., Glu, Arg, and Lys) on the molecular surface of all proteins. This kind of global change is attainable through a change in the amino acid composition coupled with alterations in the DNA base composition. The general strategies of thermophiles and psychrophiles for adaptation to higher and lower temperatures, respectively, that are suggested by the present study are discussed. PMID:12761299

  20. Adolescents Misperceive and Are Influenced By High Status Peers' Health Risk, Deviant, and Adaptive Behavior

    PubMed Central

    Helms, Sarah W.; Choukas-Bradley, Sophia; Widman, Laura; Giletta, Matteo; Cohen, Geoffrey L.; Prinstein, Mitchell J.

    2015-01-01

    Most peer influence research examines socialization between adolescents and their best friends. Yet, adolescents also are influenced by popular peers, perhaps due to misperceptions of social norms. This research examined the extent to which out-group and in-group adolescents misperceive the frequencies of peers' deviant, health risk, and adaptive behaviors in different reputation-based peer crowds (Study 1) and the prospective associations between perceptions of high status peers' and adolescents' own substance use over 2.5 years (Study 2). Study 1 examined 235 adolescents' reported deviant (vandalism, theft), health risk (substance use, sexual risk), and adaptive (exercise, studying) behavior, and their perceptions of Jocks', Populars', Burnouts', and Brains' engagement in the same behaviors. Peer nominations identified adolescents in each peer crowd. Jocks and Populars were rated as higher status than Brains and Burnouts. Results indicated that peer crowd stereotypes are caricatures. Misperceptions of high status crowds were dramatic, but for many behaviors, no differences between Populars'/Jocks' and others' actual reported behaviors were revealed. Study 2 assessed 166 adolescents' substance use and their perceptions of popular peers' (i.e., peers high in peer perceived popularity) substance use. Parallel process latent growth analyses revealed that higher perceptions of popular peers' substance use in Grade 9 (intercept) significantly predicted steeper increases in adolescents' own substance use from Grade 9 to 11 (slope). Results from both studies, utilizing different methods, offer evidence to suggest that adolescents misperceive high status peers' risk behaviors, and these misperceptions may predict adolescents' own risk behavior engagement. PMID:25365121

  1. Fatigue and environmental behavior of long fiber thermoplastic (LFT) composites

    NASA Astrophysics Data System (ADS)

    Goel, Ashutosh

    In the present work we have characterized the mechanical behavior of long fiber thermoplastic (LFT) composites (21% E-glass fiber/polypropylene) under different conditions. We start by comparing the elastic modulus of LFT predicted by a microstructure-based approach called Object Oriented Finite (OOF) element method, and compare the result with prediction from various models commonly used in the literature and the experimental value. The predictions from the models used currently in the literature did not agree well with the experimental value due to the assumptions inherent in the models. The prediction by OOF was the closest to the experimental value because of the microstructure based approach which takes into account the fiber distribution and orientation during the finite element calculation. This was followed by characterization of fatigue behavior of LFT. Samples tested along longitudinal direction showed a higher fatigue life than the transverse samples because of the preferred orientation of the fibers along the longitudinal direction developed during the processing of LFT by extrusion-compression molding process. Fatigue life decreased with increase in frequency. Hysteretic energy loss and temperature rise were measured; they depended on the stress amplitude as well as the cyclic frequency. LFT composite showed a lower temperature rise compared to neat PP because LFT has higher thermal conductivity than neat PP and thus faster heat dissipation to the surroundings occur. The hysteretic heating also led to decrease in the modulus of LFT as a function of number of cycles. The last part of the work was to study the effect of ultraviolet (UV) exposure on the microstructure and mechanical properties of LFT. Microscopic observations revealed that the damage due to UV was confined only to the surface region in the form of surface cracking and exposure of fibers to the surface in the case of LFT. FTIR and nanoindentation results showed that there was a large

  2. Thermal Effects on the Bearing Behavior of Composite Joints

    NASA Technical Reports Server (NTRS)

    Walker, Sandra Polesky

    2001-01-01

    Thermal effects on the pin-bearing behavior of an IM7/PET15 composite laminate are studied comprehensively. A hypothesis presents factors influencing a change in pin-bearing strength with a change in temperature for a given joint design. The factors include the change in the state of residual cure stress, the material properties, and the fastener fit with a change in temperature. Experiments are conducted to determine necessary lamina and laminate material property data for the IM7/PET15 being utilized in this study. Lamina material properties are determined between the assumed stress free temperature of 460 F down to -200 F. Laminate strength properties are determined for several lay-ups at the operating temperatures of 350 F, 70 F, and -200 F. A three-dimensional finite element analysis model of a composite laminate subject to compressive loading is developed. Both the resin rich layer located between lamina and the thermal residual stresses present in the laminate due to curing are determined to influence the state of stress significantly. Pin-bearing tests of several lay-ups were conducted to develop an understanding on the effect of temperature changes on the pin-bearing behavior of the material. A computational study investigating the factors influencing pin-bearing strength was performed. A finite element model was developed and used to determine the residual thermal cure stresses in the laminate containing a hole. Very high interlaminar stress concentrations were observed two elements away from the hole boundary at all three operating temperatures. The pin-bearing problem was modeled assuming a rigid frictionless pin and restraining only radial displacements at the hole boundary. A uniform negative pressure load was then applied to the straight end of the model. A solution, where thermal residual stresses were combined with the state of stress due to pin-bearing loads was evaluated. The presence of thermal residual stresses intensified the interlaminar

  3. Synaptic plasticity in a recurrent neural network for versatile and adaptive behaviors of a walking robot.

    PubMed

    Grinke, Eduard; Tetzlaff, Christian; Wörgötter, Florentin; Manoonpong, Poramate

    2015-01-01

    Walking animals, like insects, with little neural computing can effectively perform complex behaviors. For example, they can walk around their environment, escape from corners/deadlocks, and avoid or climb over obstacles. While performing all these behaviors, they can also adapt their movements to deal with an unknown situation. As a consequence, they successfully navigate through their complex environment. The versatile and adaptive abilities are the result of an integration of several ingredients embedded in their sensorimotor loop. Biological studies reveal that the ingredients include neural dynamics, plasticity, sensory feedback, and biomechanics. Generating such versatile and adaptive behaviors for a many degrees-of-freedom (DOFs) walking robot is a challenging task. Thus, in this study, we present a bio-inspired approach to solve this task. Specifically, the approach combines neural mechanisms with plasticity, exteroceptive sensory feedback, and biomechanics. The neural mechanisms consist of adaptive neural sensory processing and modular neural locomotion control. The sensory processing is based on a small recurrent neural network consisting of two fully connected neurons. Online correlation-based learning with synaptic scaling is applied to adequately change the connections of the network. By doing so, we can effectively exploit neural dynamics (i.e., hysteresis effects and single attractors) in the network to generate different turning angles with short-term memory for a walking robot. The turning information is transmitted as descending steering signals to the neural locomotion control which translates the signals into motor actions. As a result, the robot can walk around and adapt its turning angle for avoiding obstacles in different situations. The adaptation also enables the robot to effectively escape from sharp corners or deadlocks. Using backbone joint control embedded in the the locomotion control allows the robot to climb over small obstacles

  4. Synaptic plasticity in a recurrent neural network for versatile and adaptive behaviors of a walking robot

    PubMed Central

    Grinke, Eduard; Tetzlaff, Christian; Wörgötter, Florentin; Manoonpong, Poramate

    2015-01-01

    Walking animals, like insects, with little neural computing can effectively perform complex behaviors. For example, they can walk around their environment, escape from corners/deadlocks, and avoid or climb over obstacles. While performing all these behaviors, they can also adapt their movements to deal with an unknown situation. As a consequence, they successfully navigate through their complex environment. The versatile and adaptive abilities are the result of an integration of several ingredients embedded in their sensorimotor loop. Biological studies reveal that the ingredients include neural dynamics, plasticity, sensory feedback, and biomechanics. Generating such versatile and adaptive behaviors for a many degrees-of-freedom (DOFs) walking robot is a challenging task. Thus, in this study, we present a bio-inspired approach to solve this task. Specifically, the approach combines neural mechanisms with plasticity, exteroceptive sensory feedback, and biomechanics. The neural mechanisms consist of adaptive neural sensory processing and modular neural locomotion control. The sensory processing is based on a small recurrent neural network consisting of two fully connected neurons. Online correlation-based learning with synaptic scaling is applied to adequately change the connections of the network. By doing so, we can effectively exploit neural dynamics (i.e., hysteresis effects and single attractors) in the network to generate different turning angles with short-term memory for a walking robot. The turning information is transmitted as descending steering signals to the neural locomotion control which translates the signals into motor actions. As a result, the robot can walk around and adapt its turning angle for avoiding obstacles in different situations. The adaptation also enables the robot to effectively escape from sharp corners or deadlocks. Using backbone joint control embedded in the the locomotion control allows the robot to climb over small obstacles

  5. Temperature responsive behavior of polymer brush/polyelectrolyte multilayer composites.

    PubMed

    Micciulla, Samantha; Soltwedel, Olaf; Löhmann, Oliver; von Klitzing, Regine

    2016-01-28

    The complex interaction of polyelectrolyte multilayers (PEMs) physisorbed onto end-grafted polymer brushes with focus on the temperature-responsive behavior of the system is addressed in this work. The investigated brush/multilayer composite consists of a poly(styrene sulfonate)/poly(diallyldimethylammonium chloride) (PSS/PDADMAC) multilayer deposited onto the poly(N-isopropylacrylamide-b-dimethylaminoethyl methacrylate) P(NIPAM-b-DMAEMA) brush. Ellipsometry and neutron reflectometry were used to monitor the brush collapse with the thickness decrease as a function of temperature and the change in the monomer distribution perpendicular to the substrate at temperatures below, across and above the phase transition, respectively. It was found that the adsorption of PEMs onto polymer brushes had a hydrophobization effect on PDMAEMA, inducing the shift of its phase transition to lower temperatures, but without suppressing its temperature-responsiveness. Moreover, the diffusion of the free polyelectrolyte chains inside the charged brush was proved by comparing the neutron scattering length density profile of pure and the corresponding PEM-capped brushes, eased by the enhanced contrast between hydrogenated brushes and deuterated PSS chains. The results presented herein demonstrate the possibility of combining a temperature-responsive brush with polyelectrolyte multilayers without quenching the responsive behavior, even though significant interpolyelectrolyte interactions are present. This is of importance for the design of multicompartment coatings, where the brush can be used as a reservoir for the controlled release of substances and the multilayer on the top as a membrane to control the diffusion in/out by applying different stimuli. PMID:26612742

  6. Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

    PubMed Central

    CASSELLI, Denise Sá Maia; FARIA-E-SILVA, André Luis; CASSELLI, Henrique; MARTINS, Luis Roberto Marcondes

    2013-01-01

    Objective: This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations. Material and Methods: Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5ºC±2ºC followed by 55ºC±2ºC - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (a=0.05). Results: The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition. Conclusions: The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations. PMID:23559115

  7. Changes in cortical activity associated with adaptive behavior during repeated balance perturbation of unpredictable timing

    PubMed Central

    Mierau, Andreas; Hülsdünker, Thorben; Strüder, Heiko K.

    2015-01-01

    The compensation for a sudden balance perturbation, unpracticed and unpredictable in timing and magnitude is accompanied by pronounced postural instability that is suggested to be causal to falls. However, subsequent presentations of an identical perturbation are characterized by a marked decrease of the amplitude of postural reactions; a phenomenon called adaptation or habituation. This study aimed to identify cortical characteristics associated with adaptive behavior during repetitive balance perturbations based on single-trial analyses of the P1 and N1 perturbation-evoked potentials. Thirty-seven young men were exposed to ten transient balance perturbations while balancing on the dominant leg. Thirty two-channel electroencephalography (EEG), surface electromyography (EMG) of the ankle plantar flexor muscles and postural sway (i.e., Euclidean distance of the supporting platform) were recorded simultaneously. The P1 and N1 potentials were localized and the amplitude/latency was analyzed trial by trial. The best match sources for P1 and N1 potentials were located in the parietal (Brodmann area (BA) 5) and midline fronto-central cortex (BA 6), respectively. The amplitude and latency of the P1 potential remained unchanged over trials. In contrast, a significant adaptation of the N1 amplitude was observed. Similar adaptation effects were found with regard to postural sway and ankle plantarflexors EMG activity of the non-dominant (free) leg; i.e., an indicator for reduced muscular co-contraction and/or less temporary bipedal stance to regain stability. Significant but weak correlations were found between N1 amplitude and postural sway as well as EMG activity. These results highlight the important role of the midline fronto-central cortex for adaptive behavior associated with balance control. PMID:26528154

  8. Applying Computer Adaptive Testing to Optimize Online Assessment of Suicidal Behavior: A Simulation Study

    PubMed Central

    de Vries, Anton LM; de Groot, Marieke H; de Keijser, Jos; Kerkhof, Ad JFM

    2014-01-01

    Background The Internet is used increasingly for both suicide research and prevention. To optimize online assessment of suicidal patients, there is a need for short, good-quality tools to assess elevated risk of future suicidal behavior. Computer adaptive testing (CAT) can be used to reduce response burden and improve accuracy, and make the available pencil-and-paper tools more appropriate for online administration. Objective The aim was to test whether an item response–based computer adaptive simulation can be used to reduce the length of the Beck Scale for Suicide Ideation (BSS). Methods The data used for our simulation was obtained from a large multicenter trial from The Netherlands: the Professionals in Training to STOP suicide (PITSTOP suicide) study. We applied a principal components analysis (PCA), confirmatory factor analysis (CFA), a graded response model (GRM), and simulated a CAT. Results The scores of 505 patients were analyzed. Psychometric analyses showed the questionnaire to be unidimensional with good internal consistency. The computer adaptive simulation showed that for the estimation of elevation of risk of future suicidal behavior 4 items (instead of the full 19) were sufficient, on average. Conclusions This study demonstrated that CAT can be applied successfully to reduce the length of the Dutch version of the BSS. We argue that the use of CAT can improve the accuracy and the response burden when assessing the risk of future suicidal behavior online. Because CAT can be daunting for clinicians and applied scientists, we offer a concrete example of our computer adaptive simulation of the Dutch version of the BSS at the end of the paper. PMID:25213259

  9. Biological Co-Adaptation of Morphological and Composition Traits Contributes to Mechanical Functionality and Skeletal Fragility

    PubMed Central

    Tommasini, Steven M; Nasser, Philip; Hu, Bin; Jepsen, Karl J

    2008-01-01

    A path analysis was conducted to determine whether functional interactions exist among morphological, compositional, and microstructural traits for young adult human tibias. Data provided evidence that bone traits are co-adapted during ontogeny so that the sets of traits together satisfy physiological loading demands. However, certain sets of traits are expected to perform poorly under extreme load conditions. Introduction Previous data from inbred mouse strains suggested that biological processes within bone co-adapt morphological and compositional traits during ontogeny to satisfy physiological loading demands. Similar work in young adult humans showed that cortical tissue from slender tibias was stiffer, less ductile, and more susceptible to accumulating damage. Here we tested whether the relationships among morphology and tissue level mechanical properties were the result of biological processes that co-adapt physical traits, similar to those observed for the mouse skeleton. Materials and Methods Cross-sectional morphology, bone slenderness (Tt.Ar/Le), and tissue level mechanical properties were measured from tibias from 14 female (22–46 yr old) and 17 male (17–46 yr old) donors. Physical bone traits measured included tissue density, ash content, water content, porosity, and the area fractions of osteonal, interstitial, and circumferential lamellar tissues. Bivariate relationships among traits were determined using linear regression analysis. A path analysis was conducted to test the hypothesis that Tt.Ar/Le is functionally related to mineralization (ash content) and the proportion of total area occupied by cortical bone. Results Ash content correlated negatively with several traits including Tt.Ar/Le and marrow area, indicating that slender bones were constructed of tissue with higher mineralization. Path analysis revealed that slender tibias were compensated by higher mineralization and a greater area fraction of bone. Conclusions The results suggest that

  10. Mechanical Behavior of Homogeneous and Composite Random Fiber Networks

    NASA Astrophysics Data System (ADS)

    Shahsavari, Ali

    systems with large multiscale heterogeneity, which controls their mechanical behavior. This pronounced heterogeneity leads to a pronounced size and boundary condition effects on their mechanical behavior. To emphasize the source of the size effect, the network heterogeneity is characterized by analyzing the geometry of the network (density distribution), the strain field and the strain energy distribution. It is shown that the heterogeneity of the mechanical fields depends not only on the network topology, but also on the ratio between the bending and axial stiffness of fibers. In this study, the size effect is quantified and the minimum model size needed to eliminate the size effect for a given set of system parameters, is determined. The results are also used for the selection of the size of representative volume elements useful for multiscale models of fiber networks such as the sequential approach. The elastic response of composite random fiber networks in which two types of fibers are used, is studied. This analysis is performed by adding stiff fibers to a relatively softer base while considering two cases: cross-linked and non-cross-linked added fibers. The linear elastic modulus of the network is determined in terms of the system parameters, including the density of added fibers. The results are compared to the case of adding stiff fibers to a homogeneous continuum base. It is shown that there is a threshold of added fiber density, above which the axial stiffens of the base filaments controls the mechanics. In this regime, the elastic response of the composites that have network bases mimics the behavior of those with continuum bases. The results presented in this thesis are relevant for many biological and engineering fibrous materials, including connective tissue, the cellular cytoskeleton, special clothing, consumer products, filters, and dampers. It is shown that the overall behavior of the material is very sensitive to several system parameters (power law

  11. Behavior of Frame-Stiffened Composite Panels with Damage

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    2013-01-01

    NASA, the Air Force Research Laboratory and The Boeing Company have worked to develop new low-cost, light-weight composite structures for aircraft. A Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept has been developed which offers advantages over traditional metallic structures. In this concept, a stitched carbon-epoxy material system has been developed with the potential for reducing the weight and cost of transport aircraft structure by eliminating fasteners, thereby reducing part count and labor. Stitching and the use of thin skins with rod-stiffeners to move loading away from the morevulnerable outer surface produces a structurally efficient, damage tolerant design. This study focuses on the behavior of PRSEUS panels loaded in the frame direction and subjected to severe damage in the form of a severed central frame in a three-frame panel. Experimental results for a pristine two-frame panel and analytical predictions for pristine two-frame and three-frame panels as well as damaged three-frame panels are described.

  12. Iron supplementation in infancy contributes to more adaptive behavior at 10 years of age.

    PubMed

    Lozoff, Betsy; Castillo, Marcela; Clark, Katy M; Smith, Julia B; Sturza, Julie

    2014-06-01

    Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14-0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships. PMID:24717366

  13. Peer reports of adaptive behavior in twins and singletons: is twinship a risk or an advantage?

    PubMed

    Pulkkinen, Lea; Vaalamo, Inka; Hietala, Risto; Kaprio, Jaakko; Rose, Richard J

    2003-04-01

    We compared twins to their gender-matched singleton classmates in peer-assessed behavioral adjustment. Our samples include 1874 11- to 12-year-old Finnish twins (687 monozygotic, MZ; 610 same-sex dizygotic, SSDZ; 577 opposite-sex dizygotic, OSDZ) and their 23,200 non-twin classmates. Data were collected using a 30-item Multidimensional Peer Nomination Inventory containing three factors and their subscales. We found twin-singleton differences: classmates rated twin girls and boys higher than gender-matched singletons in Adaptive Behaviors (constructive, compliant, and socially active behavior), and those effects were particularly evident among OSDZ twins for assessments of social interaction, popularity, and leadership. We found no evidence that individual twins differ from singletons in Externalizing (hyperactivity-impulsivity, inattention, aggression) or Internalizing Problem Behaviors (depressive symptoms, social anxiety). Nor did we find systematic differences between MZ and SSDZ twins. Among both twins and singletons, boys exceeded girls in Externalizing, and girls exceeded boys in Internalizing Problem Behaviors. Results suggest that a twinship forms a positive developmental environment for socioemotional behavior, particularly among OSDZ twins. PMID:12723997

  14. Fractal behavior of traffic volume on urban expressway through adaptive fractal analysis

    NASA Astrophysics Data System (ADS)

    He, Hong-di; Wang, Jun-li; Wei, Hai-rui; Ye, Cheng; Ding, Yi

    2016-02-01

    In this paper, we investigate the fractal behavior of traffic volume in urban expressway based on a newly developed adaptive fractal analysis (AFA), which has a number of advantages over traditional method of detrended fluctuation analysis (DFA). Before fractal analysis, autocorrelation function was first adopted on traffic volume data and the long-range correlation behavior was found to be existed in both on-ramp and off-ramp situations. Then AFA as well as DFA was applied to further examine the fractal behavior. The results showed that the multifractality and the long-range anti-persistent behavior existed on both on-ramp and off-ramp. Additionally, multifractal analysis on weekdays and weekends are performed respectively and the results show that the degree of multifractality on weekdays is higher than that on weekends, implying that long-range correlation behaviors were more obvious on weekdays. Finally, the source of multifractality is examined with randomly shuffled and the surrogated series. Long-range correlation behaviors are identified in both on-ramp and off-ramp situations and fat-tail distributions were found to make little in the contributions of multifractality.

  15. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  16. Initial moments of adaptation to microgravity of human orientation behavior, in parabolic flight conditions

    NASA Astrophysics Data System (ADS)

    Tafforin, Carole

    1996-06-01

    The first ethological studies of astronauts' adaptation to microgravity dealt with the behavioral strategies observed during short-term space missions. No attempts had however been made to consider the initial moments of adaptation dynamics, when the subject is first submitted to conditions allowing body orientations in the full three dimensions of space. The present experimental approach was both longitudinal and transversal. It consisted of analysing, during a goal-directed orientation task in parabolic flight, the orientation behavior of 12 subjects with a past experience of 0, 30 or more than 300 parabolas. During each microgravity phase, the subjects were asked to orientate their bodies and touch, with the dominant hand, four coloured targets arranged inside the aircraft. Results showed that for inexperienced subjects, the time between two target contacts was longer than experienced subjects. They often failed to reach all targets in the series during the first parabolas. They showed right-left confusion and a preference for the "up-down" vertical body orientation. Their performance, described by the efficiency of orientation in all three dimensions, improved over time and according to the level of experience. The results are discussed for the spontaneous, preliminary and integrative stages of adaptation, emphasizing new relationships between the body references and those of the surroundings. Such experiences lead the subject to develop a new mental representation of space.

  17. A Risk-based Model Predictive Control Approach to Adaptive Interventions in Behavioral Health.

    PubMed

    Zafra-Cabeza, Ascensión; Rivera, Daniel E; Collins, Linda M; Ridao, Miguel A; Camacho, Eduardo F

    2011-07-01

    This paper examines how control engineering and risk management techniques can be applied in the field of behavioral health through their use in the design and implementation of adaptive behavioral interventions. Adaptive interventions are gaining increasing acceptance as a means to improve prevention and treatment of chronic, relapsing disorders, such as abuse of alcohol, tobacco, and other drugs, mental illness, and obesity. A risk-based Model Predictive Control (MPC) algorithm is developed for a hypothetical intervention inspired by Fast Track, a real-life program whose long-term goal is the prevention of conduct disorders in at-risk children. The MPC-based algorithm decides on the appropriate frequency of counselor home visits, mentoring sessions, and the availability of after-school recreation activities by relying on a model that includes identifiable risks, their costs, and the cost/benefit assessment of mitigating actions. MPC is particularly suited for the problem because of its constraint-handling capabilities, and its ability to scale to interventions involving multiple tailoring variables. By systematically accounting for risks and adapting treatment components over time, an MPC approach as described in this paper can increase intervention effectiveness and adherence while reducing waste, resulting in advantages over conventional fixed treatment. A series of simulations are conducted under varying conditions to demonstrate the effectiveness of the algorithm. PMID:21643450

  18. Adapting the VOICES HIV behavioral intervention for Latino men who have sex with men.

    PubMed

    O'Donnell, Lydia; Stueve, Ann; Joseph, Heather A; Flores, Stephen

    2014-04-01

    Latino men who have sex with men (MSM) are disproportionately impacted by HIV/AIDS, but few behavioral interventions address their prevention needs. Adaptation of evidence-based interventions is a pragmatic strategy that builds upon lessons learned and has the potential to fill gaps in prevention programming. Yet there are few reports of how transfers are executed and whether effectiveness is achieved. This research reports on the adaptation of VOICES/VOICES, a single-session intervention designed for heterosexual adults, into No Excuses/Sin buscar excuses for Latino MSM. To test the adapted intervention, 370 at-risk Latino MSM were enrolled in a randomized trial. At a three-month follow-up, there was a sharper decrease in unprotected intercourse in the intervention group compared to controls (59 % vs. 39 %, ANOVA p < 0.05, F = 4.10). Intervention participants also reported more condom use at last intercourse (AOR = 1.69; 95 % CI 1.02-2.81, p < 02). Findings support use of adapted models for meeting prevention needs of high-priority populations. PMID:24419993

  19. Human Behavior & Low Energy Architecture: Linking Environmental Adaptation, Personal Comfort, & Energy Use in the Built Environment

    NASA Astrophysics Data System (ADS)

    Langevin, Jared

    Truly sustainable buildings serve to enrich the daily sensory experience of their human inhabitants while consuming the least amount of energy possible; yet, building occupants and their environmentally adaptive behaviors remain a poorly characterized variable in even the most "green" building design and operation approaches. This deficiency has been linked to gaps between predicted and actual energy use, as well as to eventual problems with occupant discomfort, productivity losses, and health issues. Going forward, better tools are needed for considering the human-building interaction as a key part of energy efficiency strategies that promote good Indoor Environmental Quality (IEQ) in buildings. This dissertation presents the development and implementation of a Human and Building Interaction Toolkit (HABIT), a framework for the integrated simulation of office occupants' thermally adaptive behaviors, IEQ, and building energy use as part of sustainable building design and operation. Development of HABIT begins with an effort to devise more reliable methods for predicting individual occupants' thermal comfort, considered the driving force behind the behaviors of focus for this project. A long-term field study of thermal comfort and behavior is then presented, and the data it generates are used to develop and validate an agent-based behavior simulation model. Key aspects of the agent-based behavior model are described, and its predictive abilities are shown to compare favorably to those of multiple other behavior modeling options. Finally, the agent-based behavior model is linked with whole building energy simulation in EnergyPlus, forming the full HABIT program. The program is used to evaluate the energy and IEQ impacts of several occupant behavior scenarios in the simulation of a case study office building for the Philadelphia climate. Results indicate that more efficient local heating/cooling options may be paired with wider set point ranges to yield up to 24

  20. In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases and interface treatments. "Post-fatigue adaptation of indirect composite restorations".

    PubMed

    Rocca, Giovanni Tommaso; Gregor, Ladislav; Sandoval, Maria Jose; Krejci, Ivo; Dietschi, Didier

    2012-10-01

    The present study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II indirect composite restorations, after simulated occlusal loading. Thirty-two class II inlay cavities were prepared on human third molars, with margins located in cementum. A 1-mm composite base extending up to the cervical margins was applied on all dentin surfaces in the experimental groups; impressions were made and composite inlays fabricated. The following experimental conditions were tested: no liner (control group), flowable composite treated with soft air abrasion (experiment 1), flowable composite sandblasted (experiment 2) and restorative composite sandblasted (experiment 3). All specimens were submitted to 1,000,000 cycles with a 100-N eccentric load. Tooth-restoration margins were analysed semi-quantitatively by scanning electron microscopy before and after loading; internal adaptation was also evaluated after test completion. The percentage of perfect adaptation in enamel was 79.5% to 92.7% before loading and 73.3% to 81.9% after loading. Perfect adaptation to dentin was reduced before loading (54.8% to 77.6%) and after loading (41.9% to 63%), but no difference was found among groups for pre- and post-loading conditions. No debonding occurred between the base and composite luting. A significant, negative influence of cyclic loading was observed. The results of the present study support the use of flowable or restorative composites as base/liner underneath large class II restorations. Soft air abrasion represents a potential alternative to airborne particle abrasion for treating cavities before cementation. The application of a composite base underneath indirect composite restorations represents a feasible non-invasive alternative to surgical crown lengthening to relocate cavity margins from an intra-crevicular to supra-gingival position. PMID:22065245

  1. Treatment Sequencing for Childhood ADHD: A Multiple-Randomization Study of Adaptive Medication and Behavioral Interventions.

    PubMed

    Pelham, William E; Fabiano, Gregory A; Waxmonsky, James G; Greiner, Andrew R; Gnagy, Elizabeth M; Pelham, William E; Coxe, Stefany; Verley, Jessica; Bhatia, Ira; Hart, Katie; Karch, Kathryn; Konijnendijk, Evelien; Tresco, Katy; Nahum-Shani, Inbal; Murphy, Susan A

    2016-01-01

    Behavioral and pharmacological treatments for children with attention deficit/hyperactivity disorder (ADHD) were evaluated to address whether endpoint outcomes are better depending on which treatment is initiated first and, in case of insufficient response to initial treatment, whether increasing dose of initial treatment or adding the other treatment modality is superior. Children with ADHD (ages 5-12, N = 146, 76% male) were treated for 1 school year. Children were randomized to initiate treatment with low doses of either (a) behavioral parent training (8 group sessions) and brief teacher consultation to establish a Daily Report Card or (b) extended-release methylphenidate (equivalent to .15 mg/kg/dose bid). After 8 weeks or at later monthly intervals as necessary, insufficient responders were rerandomized to secondary interventions that either increased the dose/intensity of the initial treatment or added the other treatment modality, with adaptive adjustments monthly as needed to these secondary treatments. The group beginning with behavioral treatment displayed significantly lower rates of observed classroom rule violations (the primary outcome) at study endpoint and tended to have fewer out-of-class disciplinary events. Further, adding medication secondary to initial behavior modification resulted in better outcomes on the primary outcomes and parent/teacher ratings of oppositional behavior than adding behavior modification to initial medication. Normalization rates on teacher and parent ratings were generally high. Parents who began treatment with behavioral parent training had substantially better attendance than those assigned to receive training following medication. Beginning treatment with behavioral intervention produced better outcomes overall than beginning treatment with medication. PMID:26882332

  2. Being Mindful about the Assessment of Culture: A Cultural Analysis of Culturally Adapted Acceptance-Based Behavior Therapy Approaches

    ERIC Educational Resources Information Center

    La Roche, Martin; Lustig, Kara

    2013-01-01

    In this article we review a wide range of cultural adaptations of acceptance-based behavior therapies (ABBT) from a cultural perspective. Consistent with the cultural match model, we argue that psychotherapeutic cultural adaptations are more effective as the cultural characteristics of patients are matched to the cultural characteristics of the…

  3. Effects of Risperidone and Parent Training on Adaptive Functioning in Children with Pervasive Developmental Disorders and Serious Behavioral Problems

    ERIC Educational Resources Information Center

    Scahill, Lawrence; McDougle, Christopher J.; Aman, Michael G.; Johnson, Cynthia; Handen, Benjamin; Bearss, Karen; Dziura, James; Butter, Eric; Swiezy, Naomi G.; Arnold, L. Eugene; Stigler, Kimberly A.; Sukhodolsky, Denis D.; Lecavalier, Luc; Pozdol, Stacie L.; Nikolov, Roumen; Hollway, Jill A.; Korzekwa, Patricia; Gavaletz, Allison; Kohn, Arlene E.; Koenig, Kathleen; Grinnon, Stacie; Mulick, James A.; Yu, Sunkyung; Vitiello, Benedetto

    2012-01-01

    Objective: Children with Pervasive Developmental Disorders (PDDs) have social interaction deficits, delayed communication, and repetitive behaviors as well as impairments in adaptive functioning. Many children actually show a decline in adaptive skills compared with age mates over time. Method: This 24-week, three-site, controlled clinical trial…

  4. First-Year Students' Psychological and Behavior Adaptation to College: The Role of Coping Strategies and Social Support

    ERIC Educational Resources Information Center

    Wang, Aiping; Chen, Lang; Zhao, Bo; Xu, Yan

    2006-01-01

    This study investigates 311 first-year students' psychological and behavior adaptation to college and the mediate role of coping strategies and social support. The investigates reveal that: (1) first-year students who are from countryside, live in poor families, speak in dialects or major in science and engineering have poorer adaptation to…

  5. Implementation of CAPIO for Composite Adaptive Control of Cross-Coupled Unstable Aircraft

    NASA Technical Reports Server (NTRS)

    Yildiz, Yildiray; Kolmanovsky, Ilya V.

    2011-01-01

    This paper presents an implementation of a recently developed control allocation algorithm CAPIO (a Control Allocation technique to recover from Pilot Induced Oscillations) for composite adaptive control of an inertially cross coupled unstable aircraft. When actuators are rate-saturated due to either an aggressive pilot command, high gain of the flight control system or some anomaly in the system, the effective delay in the control loop may increase due to the phase shifting between the desired and the achieved system states. This effective time delay may deteriorate the performance or even destabilize the system in some cases, depending on the severity of rate saturation. CAPIO reduces the effective time delay by minimizing the phase shift between the commanded and the actual attitude accelerations. We present simulation results for an unstable aircraft with cross-coupling controlled with a composite adaptive controller in the presence of rate saturation. The simulations demonstrate the potential of CAPIO serving as an effective rate saturation compensator in adverse conditions.

  6. Criticality as a Set-Point for Adaptive Behavior in Neuromorphic Hardware.

    PubMed

    Srinivasa, Narayan; Stepp, Nigel D; Cruz-Albrecht, Jose

    2015-01-01

    Neuromorphic hardware are designed by drawing inspiration from biology to overcome limitations of current computer architectures while forging the development of a new class of autonomous systems that can exhibit adaptive behaviors. Several designs in the recent past are capable of emulating large scale networks but avoid complexity in network dynamics by minimizing the number of dynamic variables that are supported and tunable in hardware. We believe that this is due to the lack of a clear understanding of how to design self-tuning complex systems. It has been widely demonstrated that criticality appears to be the default state of the brain and manifests in the form of spontaneous scale-invariant cascades of neural activity. Experiment, theory and recent models have shown that neuronal networks at criticality demonstrate optimal information transfer, learning and information processing capabilities that affect behavior. In this perspective article, we argue that understanding how large scale neuromorphic electronics can be designed to enable emergent adaptive behavior will require an understanding of how networks emulated by such hardware can self-tune local parameters to maintain criticality as a set-point. We believe that such capability will enable the design of truly scalable intelligent systems using neuromorphic hardware that embrace complexity in network dynamics rather than avoiding it. PMID:26648839

  7. Criticality as a Set-Point for Adaptive Behavior in Neuromorphic Hardware

    PubMed Central

    Srinivasa, Narayan; Stepp, Nigel D.; Cruz-Albrecht, Jose

    2015-01-01

    Neuromorphic hardware are designed by drawing inspiration from biology to overcome limitations of current computer architectures while forging the development of a new class of autonomous systems that can exhibit adaptive behaviors. Several designs in the recent past are capable of emulating large scale networks but avoid complexity in network dynamics by minimizing the number of dynamic variables that are supported and tunable in hardware. We believe that this is due to the lack of a clear understanding of how to design self-tuning complex systems. It has been widely demonstrated that criticality appears to be the default state of the brain and manifests in the form of spontaneous scale-invariant cascades of neural activity. Experiment, theory and recent models have shown that neuronal networks at criticality demonstrate optimal information transfer, learning and information processing capabilities that affect behavior. In this perspective article, we argue that understanding how large scale neuromorphic electronics can be designed to enable emergent adaptive behavior will require an understanding of how networks emulated by such hardware can self-tune local parameters to maintain criticality as a set-point. We believe that such capability will enable the design of truly scalable intelligent systems using neuromorphic hardware that embrace complexity in network dynamics rather than avoiding it. PMID:26648839

  8. Brief Report: Adaptive Behavior and Cognitive Skills for Toddlers on the Autism Spectrum

    PubMed Central

    Ray-Subramanian, Corey E.; Huai, Nan; Weismer, Susan Ellis

    2012-01-01

    This study examined adaptive behavior and cognitive skills for 125 toddlers on the autism spectrum using the recently updated Vineland-II and Bayley-III. Delays in adaptive skills were apparent at two years of age. As a group, toddlers on the autism spectrum had a profile of Vineland-II standard scores in which Motor Skills > Daily Living Skills > Socialization > Communication. Vineland-II scores were significantly correlated with Bayley-III Cognitive scores. Performance on the ADOS was significantly negatively correlated with Bayley-III Cognitive standard scores and standard scores in the Daily Living Skills and Communication domains of the Vineland-II. However, calibrated ADOS scores did not contribute significant variance to Vineland-II scores beyond that predicted by age and Bayley-III scores. PMID:20697794

  9. Gender differences in adapting driving behavior to accommodate visual health limitations.

    PubMed

    Sarkin, Andrew J; Tally, Steven R; Wooldridge, Jennalee S; Choi, Kyle; Shieh, Marian; Kaplan, Robert M

    2013-12-01

    This study investigated whether men and women are equally likely to adapt their driving behaviors in response to visual limitations. Participants were 376 (222 women and 154 men) pre-surgical cataract patients from the Shiley Eye Center in La Jolla, California. All participants completed the National Eye Institute Visual Functioning Questionnaire, which assesses self-reported visual symptoms, functional limitations, and behaviors including driving during the day, at night, or in difficult conditions. Visual acuity was assessed using the log of the minimal angle of resolution (LogMAR) scale. There were no significant differences in LogMAR visual acuity between men and women who reported either that they stopped driving at night because of visual impairment or reported having no difficulty driving at night. Of participants who reported having difficulty driving at night, mean weighted LogMAR scores indicated significantly better visual acuity for women than men. There were no significant differences in LogMAR visual acuity between women and men in any of the difficult driving condition categories. Significantly more women than men reported that they stopped driving in difficult conditions because of eyesight, despite the lack of gender differences in visual acuity for this sample. We found no evidence that cataract disease had different effects on the visual acuity of older adult men and women. However, there was a significant difference between genders in self-reported driving behavior. It is possible that some women are more cautious or have less need to drive. However, failing to adapt driving behaviors to accommodate visual limitations may represent a potential behavioral public health risk for men. PMID:23852327

  10. Fracture behavior of thick, laminated graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Morris, D. H.

    1984-01-01

    The effect of laminate thickness on the fracture behavior of laminated graphite epoxy (T300/5208) composites was studied. The predominantly experimental research program included the study of the 0/+ or - 45/90 sub ns and 0/90 sub ns laminates with thickness of 8, 32, 64, 96 and 120 plies and the 0/+ or - 45 sub ns laminate with thickness of 6, 30, 60, 90 and 120 plies. The research concentrated on the measurement of fracture toughness utilizing the center-cracked tension, compact tension and three point bend specimen configurations. The development of subcritical damage at the crack tip was studied nondestructively using enhanced X-ray radiography and destructively using the laminate deply technique. The test results showed fracture toughness to be a function of laminate thickness. The fracture toughness of the 0 + or - 45/90 sub ns and 0/90 sub ns laminates decreased with increasing thickness and asymptotically approached lower bound values of 30 ksi square root of in. (1043 MPa square root of mm and 25 ksi square root of in (869 MPa square root of mm respectively. In contrast to the other two laminates, the fracture toughness of the 0/+ or - 45 sub ns laminate increased sharply with increasing thickness but reached an upper plateau value of 40 ksi square root of in (1390 MPa square root of mm) at 30 plies. Fracture toughness was independent of crack size for both thin and thick laminates for all three laminate types except for the 0/90 sub 2s laminate which spilt extensively. The center cracked tension, three point bend and compact tension specimens gave comparable results.

  11. Facets and mechanisms of adaptive pain behavior: predictive regulation and action

    PubMed Central

    Morrison, India; Perini, Irene; Dunham, James

    2013-01-01

    Neural mechanisms underlying nociception and pain perception are considered to serve the ultimate goal of limiting tissue damage. However, since pain usually occurs in complex environments and situations that call for elaborate control over behavior, simple avoidance is insufficient to explain a range of mammalian pain responses, especially in the presence of competing goals. In this integrative review we propose a Predictive Regulation and Action (PRA) model of acute pain processing. It emphasizes evidence that the nervous system is organized to anticipate potential pain and to adjust behavior before the risk of tissue damage becomes critical. Regulatory processes occur on many levels, and can be dynamically influenced by local interactions or by modulation from other brain areas in the network. The PRA model centers on neural substrates supporting the predictive nature of pain processing, as well as on finely-calibrated yet versatile regulatory processes that ultimately affect behavior. We outline several operational categories of pain behavior, from spinally-mediated reflexes to adaptive voluntary action, situated at various neural levels. An implication is that neural processes that track potential tissue damage in terms of behavioral consequences are an integral part of pain perception. PMID:24348358

  12. Behavior Change Interventions to Improve the Health of Racial and Ethnic Minority Populations: A Tool Kit of Adaptation Approaches

    PubMed Central

    Davidson, Emma M; Liu, Jing Jing; Bhopal, Raj; White, Martin; Johnson, Mark RD; Netto, Gina; Wabnitz, Cecile; Sheikh, Aziz

    2013-01-01

    Context Adapting behavior change interventions to meet the needs of racial and ethnic minority populations has the potential to enhance their effectiveness in the target populations. But because there is little guidance on how best to undertake these adaptations, work in this field has proceeded without any firm foundations. In this article, we present our Tool Kit of Adaptation Approaches as a framework for policymakers, practitioners, and researchers interested in delivering behavior change interventions to ethnically diverse, underserved populations in the United Kingdom. Methods We undertook a mixed-method program of research on interventions for smoking cessation, increasing physical activity, and promoting healthy eating that had been adapted to improve salience and acceptability for African-, Chinese-, and South Asian–origin minority populations. This program included a systematic review (reported using PRISMA criteria), qualitative interviews, and a realist synthesis of data. Findings We compiled a richly informative data set of 161 publications and twenty-six interviews detailing the adaptation of behavior change interventions and the contexts in which they were undertaken. On the basis of these data, we developed our Tool Kit of Adaptation Approaches, which contains (1) a forty-six-item Typology of Adaptation Approaches; (2) a Pathway to Adaptation, which shows how to use the Typology to create a generic behavior change intervention; and (3) RESET, a decision tool that provides practical guidance on which adaptations to use in different contexts. Conclusions Our Tool Kit of Adaptation Approaches provides the first evidence-derived suite of materials to support the development, design, implementation, and reporting of health behavior change interventions for minority groups. The Tool Kit now needs prospective, empirical evaluation in a range of intervention and population settings. PMID:24320170

  13. Chemical composition of whole body and carcass of Bos indicus and tropically adapted Bos taurus breeds.

    PubMed

    Bonilha, S F M; Tedeschi, L O; Packer, I U; Razook, A G; Nardon, R F; Figueiredo, L A; Alleoni, G F

    2011-09-01

    Relationships between the chemical composition of the 9th- to 11th-rib section and the chemical composition of the carcass and empty body were evaluated for Bos indicus (108 Nellore and 36 Guzerah; GuS) and tropically adapted Bos taurus (56 Caracu; CaS) bulls, averaging 20 to 24 mo of age at slaughter. Nellore cattle were represented by 56 animals from the selected herd (NeS) and 52 animals from the control herd (NeC). The CaS and GuS bulls were from selected herds. Selected herds were based on 20 yr of selection for postweaning BW. Carcass composition was obtained after grinding, homogenizing, sampling, and analyzing soft tissue and bones. Similarly, empty body composition was obtained after grinding, homogenizing, sampling, analyzing, and combining blood, hide, head + feet, viscera, and carcass. Bulls were separated into 2 groups. Group 1 was composed of 36 NeS, 36 NeC, 36 CaS, and 36 GuS bulls and had water, ether extract (EE), protein, and ash chemically determined in the 9th- to 11th-rib section and in the carcass. Group 2 was composed of 20 NeS, 16 NeC, and 20 CaS bulls and water, EE, protein, and ash were determined in the 9th- to 11th-rib section, carcass, and empty body. Linear regressions were developed between the carcass and the 9th- to 11th-rib section compositions for group 1 and between carcass and empty body compositions for group 2. The 9th- to 11th-rib section percentages of water (RWt) and EE (RF) predicted the percentages of carcass water (CWt) and carcass fat (CF) with high precision: CWt, % = 29.0806 + 0.4873 × RWt, % (r(2) = 0.813, SE = 1.06) and CF, % = 10.4037 + 0.5179 × RF, % (r(2) = 0.863, SE = 1.26), respectively. Linear regressions between percentage of CWt and CF and empty body water (EBWt) and empty body fat (EBF) were also predicted with high precision: EBWt, % = -9.6821 + 1.1626 × CWt, % (r(2) = 0.878, SE = 1.43) and EBF, % = 0.3739 + 1.0386 × CF, % (r(2) = 0.982, SE = 0.65), respectively. Chemical composition of the 9th- to 11

  14. Creep behavior of tungsten/niobium and tungsten/niobium-1 percent zirconium composites

    NASA Technical Reports Server (NTRS)

    Petrasek, Donald W.; Titran, Robert H.

    1988-01-01

    The creep behavior and microstructural stability of tungsten fiber reinforced niobium and niobium 1 percent zirconium was determined at 1400 and 1500 K in order to assess the potential of this material for use in advanced space power systems. The creep behavior of the composite materials could be described by a power law creep equation. A linear relationship was found to exist between the minimum creep rate of the composite and the inverse of the composite creep rupture life. The composite materials had an order of magnitude increase in stress to achieve 1 percent creep strain and in rupture strength at test temperatures of 1400 and 1500 K compared to unreinforced material. The composite materials were also stronger than the unreinforced materials by an order of magnitude when density was taken into consideration. Results obtained on the creep behavior and microstructural stability of the composites show significant potential improvement in high temperature properties and mass reduction for space power system components.

  15. Abrasive wear behavior of P/M titanium metal-matrix composites

    SciTech Connect

    Alman, D.E.; Hawk, J.A.; Simmons, J.W.

    1997-01-01

    The abrasive wear behavior of titanium metal-matrix composites produced by powder metallurgical techniques was studied. Ti powder was mixed with 0, 20, or 40 volume percent (v%) TiB2, TiC, TiN, SiC, an B4C powder to produce a composite powder blend. The blends were consolidated by hot-pressing at 1200° C and 20 MPa for 2 hours. Also a series of Ti-TiB2 composites was consolidated by press and sinter techniques. Two-body abrasive wear resistance, of the composites worn against either SiC or garnet particles, was evaluated using a pin-on-drum apparatus. The wear behavior of the composites was correlated to the physical properties (e.g., microstructure, sintered density, hardness, strength) of the composites, and compared to the behavior of conventional cast adn wrought Ti and other alloys.

  16. Life-history evolution at the molecular level: adaptive amino acid composition of avian vitellogenins

    PubMed Central

    Hughes, Austin L.

    2015-01-01

    Avian genomes typically encode three distinct vitellogenin (VTG) egg yolk proteins (VTG1, VTG2 and VTG3), which arose by gene duplication prior to the most recent common ancestor of birds. Analysis of VTG sequences from 34 avian species in a phylogenetic framework supported the hypothesis that VTG amino acid composition has co-evolved with embryo incubation time. Embryo incubation time was positively correlated with the proportions of dietary essential amino acids (EAAs) in VTG1 and VTG2, and with the proportion of sulfur-containing amino acids in VTG3. These patterns were seen even when only semi-altricial and/or altricial species were considered, suggesting that the duration of embryo incubation is a major selective factor on the amino acid composition of VTGs, rather than developmental mode alone. The results are consistent with the hypothesis that the level of EAAs provided to the egg represents an adaptation to the loss of amino acids through breakdown over the course of incubation and imply that life-history phenotypes and VTG amino acid composition have co-evolved throughout the evolutionary history of birds. PMID:26224713

  17. Computational simulation of intermingled-fiber hybrid composite behavior

    NASA Technical Reports Server (NTRS)

    Mital, Subodh K.; Chamis, Christos C.

    1992-01-01

    Three-dimensional finite-element analysis and a micromechanics based computer code ICAN (Integrated Composite Analyzer) are used to predict the composite properties and microstresses of a unidirectional graphite/epoxy primary composite with varying percentages of S-glass fibers used as hydridizing fibers at a total fiber volume of 0.54. The three-dimensional finite-element model used in the analyses consists of a group of nine fibers, all unidirectional, in a three-by-three unit cell array. There is generally good agreement between the composite properties and microstresses obtained from both methods. The results indicate that the finite-element methods and the micromechanics equations embedded in the ICAN computer code can be used to obtain the properties of intermingled fiber hybrid composites needed for the analysis/design of hybrid composite structures. However, the finite-element model should be big enough to be able to simulate the conditions assumed in the micromechanics equations.

  18. Crystallization behavior and glass formation of selected lunar compositions.

    NASA Technical Reports Server (NTRS)

    Scherer, G.; Hopper, R. W.; Uhlmann, D. R.

    1972-01-01

    The kinetics of crystal growth have been determined over a wide range of temperature, from 800 to 1219 C, for lunar compositions 14259 and 14310. At all temperatures for both compositions the extent of crystal growth is found to be a linear function of time. For both materials, the growth rate versus temperature relations exhibit the form generally found with glass-forming materials. At all temperatures measured, the crystal growth rate of composition 14259 is smaller than that of composition 14310. The maximum growth rate for both compositions occurs at a temperature of about 1120 C. The growth rate data are combined with viscosity data obtained on the same compositions to construct the reduced growth rate versus undercooling relations.

  19. Modeling the Stress Strain Behavior of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2006-01-01

    Woven SiC fiber reinforced SiC matrix composites represent one of the most mature composite systems to date. Future components fabricated out of these woven ceramic matrix composites are expected to vary in shape, curvature, architecture, and thickness. The design of future components using woven ceramic matrix composites necessitates a modeling approach that can account for these variations which are physically controlled by local constituent contents and architecture. Research over the years supported primarily by NASA Glenn Research Center has led to the development of simple mechanistic-based models that can describe the entire stress-strain curve for composite systems fabricated with chemical vapor infiltrated matrices and melt-infiltrated matrices for a wide range of constituent content and architecture. Several examples will be presented that demonstrate the approach to modeling which incorporates a thorough understanding of the stress-dependent matrix cracking properties of the composite system.

  20. Probabilistic simulation of multi-scale composite behavior

    NASA Technical Reports Server (NTRS)

    Liaw, D. G.; Shiao, M. C.; Singhal, S. N.; Chamis, Christos C.

    1993-01-01

    A methodology is developed to computationally assess the probabilistic composite material properties at all composite scale levels due to the uncertainties in the constituent (fiber and matrix) properties and in the fabrication process variables. The methodology is computationally efficient for simulating the probability distributions of material properties. The sensitivity of the probabilistic composite material property to each random variable is determined. This information can be used to reduce undesirable uncertainties in material properties at the macro scale of the composite by reducing the uncertainties in the most influential random variables at the micro scale. This methodology was implemented into the computer code PICAN (Probabilistic Integrated Composite ANalyzer). The accuracy and efficiency of this methodology are demonstrated by simulating the uncertainties in the material properties of a typical laminate and comparing the results with the Monte Carlo simulation method. The experimental data of composite material properties at all scales fall within the scatters predicted by PICAN.

  1. Behavior of grid-stiffened composite structures under transverse loading

    NASA Astrophysics Data System (ADS)

    Gan, Changsheng

    The energy absorption characteristics and failure modes of grid-stiffened composite plates under transverse load were studied in detail. Several laboratory scale composite grid plates were fabricated by using co-mingled E-glass fiber/polypropylene matrix and carbon/nylon composites in a thermoplastic stamping process. Both experimental and finite element approaches were used to evaluate and understand the role of major failure modes on the performance of damaged grid-stiffened composite plates under transverse load. The load-deflection responses of grid-stiffened composite plates were determined and compared with those of sandwich composite plates of the same size. The failure modes of grid-stiffened composite plates under different load conditions were investigated and used as the basis for FEA models. The intrinsic strength properties of constituent composite materials were measured by using either three point bending or tensile test and were used as input data to the FEA models. Several FEA models including the major failure modes based on the experimental results were built to simulate the damage processes of grid-stiffened composite plates under transverse load. A FORTRAN subroutine was implemented within the ABAQUS code to incorporate the material failure models. Effects of damage on the modal frequencies and loss factors of grid-stiffened composite plates were also investigated experimentally. Experimental and simulation results showed that sandwich composite specimens failed catastrophically with the load dropping sharply at the displacement corresponding to initial and final failure. However, grid-stiffened composite specimens failed in a more gradual and forgiving way in a sequence of relatively small load drops. No catastrophic load drops were observed in the grid structures over the range of displacements investigated here. The SEA values of the grid composite specimens are typically higher than those of the sandwich specimens with the same boundary

  2. Low cycle fatigue behavior of aluminum/stainless steel composites

    NASA Technical Reports Server (NTRS)

    Bhagat, R. B.

    1983-01-01

    Composites consisting of an aluminum matrix reinforced with various volume fractions of stainless steel wire were fabricated by hot die pressing under various conditions of temperature, time, and pressure. The composites were tested in plane bending to complete fracture under cycle loading, and the results were analyzed on a computer to obtain a statistically valid mathematical relationship between the low-cycle fatigue life and the fiber volume fraction of the composite. The fractured surfaces of the composites were examined by scanning electron microscopy to identify the characteristic features of fatigue damage. Fatigue damage mechanisms are proposed and discussed.

  3. The elevated temperature behavior of particle reinforced Al matrix composites

    SciTech Connect

    Lloyd, D.J.

    1994-12-31

    The elevated temperature modulus, strength and creep of SiC particle reinforced composites produced by the DURALCAN{trademark} are discussed. It is shown that the reinforcing particles provide an increased modulus over the complete temperature range studied, and the temperature dependence of the composite modulus is controlled by the temperature dependence of the matrix modulus. The composite strength decreases with increasing temperature, reflecting softening of the matrix due to over aging, and as a result, is dependent on the thermal stability of the matrix. The particles provide increased creep resistance, and there are differences between the creep of melt processed composites and those produced by powder metallurgy.

  4. Hard tissue as a composite material. I - Bounds on the elastic behavior.

    NASA Technical Reports Server (NTRS)

    Katz, J. L.

    1971-01-01

    Recent determination of the elastic moduli of hydroxyapatite by ultrasonic methods permits a re-examination of the Voigt or parallel model of the elastic behavior of bone, as a two phase composite material. It is shown that such a model alone cannot be used to describe the behavior of bone. Correlative data on the elastic moduli of dentin, enamel and various bone samples indicate the existence of a nonlinear dependence of elastic moduli on composition of hard tissue. Several composite models are used to calculate the bounds on the elastic behavior of these tissues. The limitations of these models are described, and experiments to obtain additional critical data are discussed.

  5. LABRADOR: a learning autonomous behavior-based robot for adaptive detection and object retrieval

    NASA Astrophysics Data System (ADS)

    Yamauchi, Brian; Moseley, Mark; Brookshire, Jonathan

    2013-01-01

    As part of the TARDEC-funded CANINE (Cooperative Autonomous Navigation in a Networked Environment) Program, iRobot developed LABRADOR (Learning Autonomous Behavior-based Robot for Adaptive Detection and Object Retrieval). LABRADOR was based on the rugged, man-portable, iRobot PackBot unmanned ground vehicle (UGV) equipped with an explosives ordnance disposal (EOD) manipulator arm and a custom gripper. For LABRADOR, we developed a vision-based object learning and recognition system that combined a TLD (track-learn-detect) filter based on object shape features with a color-histogram-based object detector. Our vision system was able to learn in real-time to recognize objects presented to the robot. We also implemented a waypoint navigation system based on fused GPS, IMU (inertial measurement unit), and odometry data. We used this navigation capability to implement autonomous behaviors capable of searching a specified area using a variety of robust coverage strategies - including outward spiral, random bounce, random waypoint, and perimeter following behaviors. While the full system was not integrated in time to compete in the CANINE competition event, we developed useful perception, navigation, and behavior capabilities that may be applied to future autonomous robot systems.

  6. Agouti-related peptide neural circuits mediate adaptive behaviors in the starved state.

    PubMed

    Padilla, Stephanie L; Qiu, Jian; Soden, Marta E; Sanz, Elisenda; Nestor, Casey C; Barker, Forrest D; Quintana, Albert; Zweifel, Larry S; Rønnekleiv, Oline K; Kelly, Martin J; Palmiter, Richard D

    2016-05-01

    In the face of starvation, animals will engage in high-risk behaviors that would normally be considered maladaptive. Starving rodents, for example, will forage in areas that are more susceptible to predators and will also modulate aggressive behavior within a territory of limited or depleted nutrients. The neural basis of these adaptive behaviors likely involves circuits that link innate feeding, aggression and fear. Hypothalamic agouti-related peptide (AgRP)-expressing neurons are critically important for driving feeding and project axons to brain regions implicated in aggression and fear. Using circuit-mapping techniques in mice, we define a disynaptic network originating from a subset of AgRP neurons that project to the medial nucleus of the amygdala and then to the principal bed nucleus of the stria terminalis, which suppresses territorial aggression and reduces contextual fear. We propose that AgRP neurons serve as a master switch capable of coordinating behavioral decisions relative to internal state and environmental cues. PMID:27019015

  7. Genomic Response to Selection for Predatory Behavior in a Mammalian Model of Adaptive Radiation.

    PubMed

    Konczal, Mateusz; Koteja, Paweł; Orlowska-Feuer, Patrycja; Radwan, Jacek; Sadowska, Edyta T; Babik, Wiesław

    2016-09-01

    If genetic architectures of various quantitative traits are similar, as studies on model organisms suggest, comparable selection pressures should produce similar molecular patterns for various traits. To test this prediction, we used a laboratory model of vertebrate adaptive radiation to investigate the genetic basis of the response to selection for predatory behavior and compare it with evolution of aerobic capacity reported in an earlier work. After 13 generations of selection, the proportion of bank voles (Myodes [=Clethrionomys] glareolus) showing predatory behavior was five times higher in selected lines than in controls. We analyzed the hippocampus and liver transcriptomes and found repeatable changes in allele frequencies and gene expression. Genes with the largest differences between predatory and control lines are associated with hunger, aggression, biological rhythms, and functioning of the nervous system. Evolution of predatory behavior could be meaningfully compared with evolution of high aerobic capacity, because the experiments and analyses were performed in the same methodological framework. The number of genes that changed expression was much smaller in predatory lines, and allele frequencies changed repeatably in predatory but not in aerobic lines. This suggests that more variants of smaller effects underlie variation in aerobic performance, whereas fewer variants of larger effects underlie variation in predatory behavior. Our results thus contradict the view that comparable selection pressures for different quantitative traits produce similar molecular patterns. Therefore, to gain knowledge about molecular-level response to selection for complex traits, we need to investigate not only multiple replicate populations but also multiple quantitative traits. PMID:27401229

  8. Effect of lining with a flowable composite on internal adaptation of direct composite restorations using all-in-one adhesive systems.

    PubMed

    Yahagi, Chika; Takagaki, Tomohiro; Sadr, Alireza; Ikeda, Masaomi; Nikaido, Toru; Tagami, Junji

    2012-01-01

    The purpose of this study was to evaluate the effect of lining with a flowable composite on internal adaptation of composite restorations using three all-in-one adhesive systems; Bond Force (BF), G-Bond Plus (GP), and OptiBond All-in-one (OP), and a two-step self-etching adhesive system; Clearfil SE Bond (SE). They were applied to each cylindrical cavity prepared on the human dentin. The cavity surface was lined with/without a flowable resin composite prior to filling with a resin composite (FL/NL). After water storage for 24 h, the specimens were sectioned and polished, and internal adaptation of the restorations was assessed using a confocal laser scanning microscopy. For SE, a perfect cavity adaptation was recognized in both FL and NL. For BF, GP and OP, cavity adaptation was material dependent in NL, whereas no gap formation was observed in FL. However, voids formation was observed at the composite-adhesive-dentin interface in every all-in-one adhesive system. PMID:22673475

  9. Migration behavior of landfill leachate contaminants through alternative composite liners.

    PubMed

    Varank, Gamze; Demir, Ahmet; Top, Selin; Sekman, Elif; Akkaya, Ebru; Yetilmezsoy, Kaan; Bilgili, M Sinan

    2011-08-01

    Four identical pilot-scale landfill reactors with different alternative composite liners were simultaneously operated for a period of about 540 days to investigate and to simulate the migration behaviors of phenolic compounds (phenol, 2-CP, 2-MP, 3-MP, 4-MP, 2-NP, 4-NP, 2,4-DNP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,6-TeCP, PCP) and heavy metals (Pb, Cu, Zn, Cr, Cd, Ni) from landfill leachate to the groundwater. Alternative landfill liners of four reactors consist of R1: Compacted clay liner (10 cm+10 cm, k=10(-8)m/sn), R2: Geomembrane (2 mm HDPE)+compacted clay liner (10 cm+10 cm, k=10⁻⁸ m/sn), R3: Geomembrane (2 mm HDPE)+compacted clay liner (10 cm, k=10⁻⁸ m/sn)+bentonite liner (2 cm)+compacted clay liner (10 cm, k=10⁻⁸ m/sn), and R4: Geomembrane (2 mm HDPE)+compacted clay liner (10 cm, k=10⁻⁸ m/sn)+zeolite liner (2 cm)+compacted clay liner (10 cm, k=10⁻⁸ m/sn). Wastes representing Istanbul municipal solid wastes were disposed in the reactors. To represent bioreactor landfills, reactors were operated by leachate recirculation. To monitor and control anaerobic degradation in the reactors, variations of conventional parameters (pH, alkalinity, chloride, conductivity, COD, TOC, TKN, ammonia and alcaly metals) were also investigated in landfill leachate samples. The results of this study showed that about 35-50% of migration of organic contaminants (phenolic compounds) and 55-100% of migration of inorganic contaminants (heavy metals) to the model groundwater could be effectively reduced with the use of bentonite and zeolite materials in landfill liner systems. Although leachate contaminants can reach to the groundwater in trace concentrations, findings of this study concluded that the release of these compounds from landfill leachate to the groundwater may potentially be of an important environmental concern based on the experimental findings. PMID:21621822

  10. Neocortical Tet3-mediated accumulation of 5-hydroxymethylcytosine promotes rapid behavioral adaptation.

    PubMed

    Li, Xiang; Wei, Wei; Zhao, Qiong-Yi; Widagdo, Jocelyn; Baker-Andresen, Danay; Flavell, Charlotte R; D'Alessio, Ana; Zhang, Yi; Bredy, Timothy W

    2014-05-13

    5-hydroxymethylcytosine (5-hmC) is a novel DNA modification that is highly enriched in the adult brain and dynamically regulated by neural activity. 5-hmC accumulates across the lifespan; however, the functional relevance of this change in 5-hmC and whether it is necessary for behavioral adaptation have not been fully elucidated. Moreover, although the ten-eleven translocation (Tet) family of enzymes is known to be essential for converting methylated DNA to 5-hmC, the role of individual Tet proteins in the adult cortex remains unclear. Using 5-hmC capture together with high-throughput DNA sequencing on individual mice, we show that fear extinction, an important form of reversal learning, leads to a dramatic genome-wide redistribution of 5-hmC within the infralimbic prefrontal cortex. Moreover, extinction learning-induced Tet3-mediated accumulation of 5-hmC is associated with the establishment of epigenetic states that promote gene expression and rapid behavioral adaptation. PMID:24757058

  11. Effects of Sex and Gender on Adaptation to Space: Behavioral Health

    PubMed Central

    Bale, Tracy L.; Epperson, C. Neill; Kornstein, Susan G.; Leon, Gloria R.; Palinkas, Lawrence A.; Stuster, Jack W.; Dinges, David F.

    2014-01-01

    Abstract This article is part of a larger body of work entitled, “The Impact of Sex and Gender on Adaptation to Space.” It was developed in response to a recommendation from the 2011 National Academy of Sciences Decadal Survey, “Recapturing a Future for Space Exploration: Life and Physical Sciences for a New Era,” which emphasized the need to fully understand sex and gender differences. In this article, our workgroup—consisting of expert scientists and clinicians from academia and the private sector—investigated and summarized the current body of published and unpublished human research performed to date related to sex- and gender-based differences in behavioral adaptations to human spaceflight. This review identifies sex-related differences in: (1) sleep, circadian rhythms, and neurobehavioral measures; (2) personality, group interactions, and work performance and satisfaction; and (3) stress and clinical disorders. Differences in these areas substantially impact the risks and optimal medical care required by space-faring women. To ensure the health and safety of male and female astronauts during long-duration space missions, it is imperative to understand the influences that sex and gender have on behavioral health changes occurring during spaceflight. PMID:25259837

  12. Effects of sex and gender on adaptation to space: behavioral health.

    PubMed

    Goel, Namni; Bale, Tracy L; Epperson, C Neill; Kornstein, Susan G; Leon, Gloria R; Palinkas, Lawrence A; Stuster, Jack W; Dinges, David F

    2014-11-01

    This article is part of a larger body of work entitled, "The Impact of Sex and Gender on Adaptation to Space." It was developed in response to a recommendation from the 2011 National Academy of Sciences Decadal Survey, "Recapturing a Future for Space Exploration: Life and Physical Sciences for a New Era," which emphasized the need to fully understand sex and gender differences. In this article, our workgroup-consisting of expert scientists and clinicians from academia and the private sector-investigated and summarized the current body of published and unpublished human research performed to date related to sex- and gender-based differences in behavioral adaptations to human spaceflight. This review identifies sex-related differences in: (1) sleep, circadian rhythms, and neurobehavioral measures; (2) personality, group interactions, and work performance and satisfaction; and (3) stress and clinical disorders. Differences in these areas substantially impact the risks and optimal medical care required by space-faring women. To ensure the health and safety of male and female astronauts during long-duration space missions, it is imperative to understand the influences that sex and gender have on behavioral health changes occurring during spaceflight. PMID:25259837

  13. Post-impact behavior of composite solid rocket motor cases

    NASA Technical Reports Server (NTRS)

    Highsmith, Alton L.

    1992-01-01

    In recent years, composite materials have seen increasing use in advanced structural applications because of the significant weight savings they offer when compared to more traditional engineering materials. The higher cost of composites must be offset by the increased performance that results from reduced structural weight if these new materials are to be used effectively. At present, there is considerable interest in fabricating solid rocket motor cases out of composite materials, and capitalizing on the reduced structural weight to increase rocket performance. However, one of the difficulties that arises when composite materials are used is that composites can develop significant amounts of internal damage during low velocity impacts. Such low velocity impacts may be encountered in routine handling of a structural component like a rocket motor case. The ability to assess the reduction in structural integrity of composite motor cases that experience accidental impacts is essential if composite rocket motor cases are to be certified for manned flight. The study described herein was an initial investigation of damage development and reduction of tensile strength in an idealized composite subjected to low velocity impacts.

  14. Ballistic impact fatigue behavior of spectra fiber-reinforced composites

    SciTech Connect

    Song, J.W.; Lee, B.L.

    1994-12-31

    The study examined the penetration failure mechanisms of Spectra fiber-reinforced composites under ballistic impact and assessed the roles played by resin matrix properties in controlling the process of impact damage propagation. In order to observe gradual propagation of damage, a concept of impact fatigue was introduced by subjecting the composite plates to a multiple number of repeated ballistic impact. When the striking velocity of,a projectile was below the ballistic limit, repeated impact resulted in a progressive growth of local delamination until full penetration of the projectile occurs. Preliminary results indicated that the vinyl ester resin matrix composites have a higher ballistic limit and longer impact fatigue life at a given striking velocity than the polyurethane matrix composites. Based on the test results of dynamic mechanical properties, more localized delamination of polyurethane matrix composites was attributed to a greater degree of stress wave attenuation and lower bending stiffness of material system.

  15. Thermal Conductivity behavior of MWCNT based PMMA and PC composites

    NASA Astrophysics Data System (ADS)

    Dubey, Girija; Jindal, Prashant; Bhandari, Rajiv; Dhiman, Neha; Bajaj, Chetan; Jindal, Vijay

    Poly methyl methacrylate (PMMA) and Polycarbonate (PC) are low cost polymer materials which can be easily transformed into desired shapes for various applications. However they have poor mechanical, thermal and electrical properties which are required to be enhanced to widen their scope of applications specifically where along with high strength, rapid heat transfer is essential. Multi Walled Carbon nanotubes (MWCNTs) are excellent new materials having extraordinary mechanical and transport properties. We will report results of fabricating composites of varying compositions of MWCNTs with PMMA and PC and their thermal conductivity behaviour using simple transient heat flow methods. The samples in disk shapes of around 2 cm diameters and 0.2 cm thickness with MWCNT compositions varying up to 10 wt% were fabricated. We found that both PMMA and PC measured high thermal conductivity with increase in the composition of CNTs. The thermal conductivity of 10wt% MWCNT/PMMA composite increased by nearly two times in comparison to pure PMMA.

  16. Dynamic Mechanical Behavior of Boron Carbide Based Composites

    NASA Astrophysics Data System (ADS)

    Hayun, S.; Frage, N.; Dariel, M. P.; Zaretsky, E.

    2007-12-01

    The dynamic response of two boron carbide-based composites was studied in planar impact experiments (impact velocities 100-1000 m/sec) using a 25 mm gas gun. The composites were fabricated by infiltration of compacted B4C and partially sintered B4C preforms by molten Si. In the course of the infiltration process, the liquid silicon reacts with the B4C phase resulting in the formation of the SiC and B12(B,C,Si)3 phases along with some residual silicon present in the infiltrated composites. The velocities of the sample-PMMA window interface were monitored continuously by VISAR. The composites display a relatively high HEL (12-14 GPa) and spall strength (about 1 GPa) values. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were used to characterize the fracture surface. The correlation between the microstructure of the infiltrated composites and their dynamic response is discussed.

  17. Adaptations in medial prefrontal cortex function associated with amphetamine-induced behavioral sensitization

    PubMed Central

    Gulley, Joshua M.; Stanis, Jessica J.

    2010-01-01

    Neuroadaptations in the prefrontal cortex (PFC) are hypothesized to play an important role in the behavioral changes associated with repeated psychostimulant exposure, but there are few published studies that measure neuronal activity during the development and expression of sensitization. To address this, we recorded single neuron activity in the medial PFC (mPFC) of male rats that were exposed for five days to saline or amphetamine (AMPH; 1.0 mg/kg, i.p.) and then given saline or AMPH challenges following a three-day withdrawal. We found that rats exposed to AMPH developed locomotor sensitization to the drug that emerged on the fifth treatment session and became statistically significant at AMPH challenge. This was associated with no change in baseline (i.e., pre-injection) activity of mPFC neurons across the treatment or challenge sessions. Following the first AMPH injection, mPFC neurons responded primarily with reductions in firing, with the overall pattern and magnitude of responses remaining largely similar following repeated treatment. The exception was in the minority of cells that respond to AMPH with increases in firing rate. In this population, the magnitude of excitations peaked during the fifth AMPH exposure and was still relatively elevated at the AMPH challenge. Furthermore, these units increased firing during a saline challenge that was given to assess associative conditioning. These results suggest that AMPH-induced adaptations in mPFC function are not as apparent as AMPH-induced adaptations in behavior. When mPFC adaptations do occur, they appear limited to the population of neurons that increase their firing in response to AMPH. PMID:20035836

  18. A nickel-carbon-fibre composite for large adaptive mirrors: fabrication methods and properties.

    PubMed

    Thompson, S J; Brooks, D; Doel, A P

    2008-01-21

    We present results from our recent research into carbon-fibre composite (CFC) mirror fabrication for optical and infra-red applications. In particular this research is aimed towards the next generation of extremely large telescopes to offer an alternative to thin glass shell adaptive secondary mirrors. We address the issues involved with CFC mirror production, in particular the accuracy of the form replication process, a suitable surface for polishing to optical quality, no fibre print-through, environmental stability (shape change due to thermal and moisture variations), material uniformity and lifetime. We have performed experiments into the effectiveness of cold electroplating thick nickel coatings to totally encapsulate the CFC base substrate; the manufacturing procedure and properties of the Ni-CFC mirror are described here. PMID:18542204

  19. Retinal isomer composition in some bacteriorhodopsin mutants under light and dark adaptation conditions

    SciTech Connect

    Song, L.; Yang, D.; El-Sayed, M.A.; Lanyi, J.K.

    1995-06-15

    The isomeric composition of retinal was measured in a number of bacteriorhodopsin (bR) mutants (D85N, D212N, R82A, Y185F, and D115N) under various conditions, using a rapid retinal extraction technique followed by HPLC analysis. Besides the 13-cis and the all-trans retinal isomers observed in wild type (wt) bR under physiological conditions, the 11-cis and 9-cis retinal isomers were observed in variable but minor amounts in the bR mutants. In addition, the values of the equilibrium constant at two temperatures and the enthalpy change for the all-trans to 13-cis isomerization process in the dark-adapted state of D212N, D85N, deionized blue bR, and wt bR were determined. We find that perturbation of the retinal cavity (pocket) by residue replacement changes the relative thermal stability of the different retinal isomers, allowing for thermal-and/or photoisomerization of the retinal chromophore along C{sub 9}-C{sub 10} and C{sub 11}-C{sub 12} bonds to moderately compete with the isomerization around the C{sub 13}-C{sub 14} bond. The bR mutants expressed in Halobacterium salinarium studied in the present work showed normal 13-cis to all-trans light adaptation, in contrast with abnormal all-trans to 13-cis light adaptation observed for D212E, D212A, and D212N expressed in Escherichia coli, suggesting an influence of the purple membrane lattice and/or the lipids on the stability of the different retinal isomers within the protein. 38 refs., 2 tabs.

  20. Effect of egg composition and oxidoreductase on adaptation of Tibetan chicken to high altitude.

    PubMed

    Jia, C L; He, L J; Li, P C; Liu, H Y; Wei, Z H

    2016-07-01

    Tibetan chickens have good adaptation to hypoxic conditions, which can be reflected by higher hatchability than lowland breeds when incubated at high altitude. The objective of this trial was to study changes in egg composition and metabolism with regards the adaptation of Tibetan chickens to high altitude. We measured the dry weight of chicken embryos, egg yolk, and egg albumen, and the activity of lactate dehydrogenase (LDH) and succinic dehydrogenase (SDH) in breast muscle, heart, and liver from embryos of Tibetan chicken and Dwarf chicken (lowland breed) incubated at high (2,900 m) and low (100 m) altitude. We found that growth of chicken embryos was restricted at high altitude, especially for Dwarf chicken embryos. In Tibetan chicken, the egg weight was lighter, but the dry weight of egg yolk was heavier than that of Dwarf chicken. The LDH activities of the three tissues from the high altitude groups were respectively higher than those of the lowland groups from d 15 to hatching, except for breast muscle of Tibetan chicken embryos on d 15. In addition, under the high altitude environment, the heart tissue from Tibetan chicken had lower LDH activity than that from Dwarf chicken at d 15 and 18. The lactic acid content of blood from Tibetan chicken embryos was lower than that of Dwarf chicken at d 12 and 15 of incubation at high altitude. There was no difference in SDH activity in the three tissues between the high altitude groups and the lowland groups except in three tissues of hatchlings and at d 15 of incubation in breast muscle, nor between the two breeds at high altitude except in the heart of hatchlings. Consequently, the adaptation of Tibetan chicken to high altitude may be associated with higher quantities of yolk in the egg and a low metabolic oxygen demand in tissue, which illuminate the reasons that the Tibetan chicken have higher hatchability with lower oxygen transport ability. PMID:26957629

  1. Friction and wear behavior of graphite fiber reinforced polymide composites

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.; Sliney, H. E.

    1977-01-01

    The friction and wear rate characteristics of 50/50 (weight percent) graphite fiber polyimide composites were studied by sliding metallic hemispherically tipped riders against disks made from the composites. Two different polyimides and two different graphite fibers were evaluated. Also studied were such variables as the effect of moisture in an air atmosphere; the effect of temperature; and the effect of different sliding speeds. In general, wear to the the metallic riders was negligible, and composite wear increased at a constant rate as a function of number of sliding cycles.

  2. Examining the Specific Effects of Context on Adaptive Behavior and Achievement in a Rural African Community: Six Case Studies from Rural Areas of Southern Province, Zambia

    ERIC Educational Resources Information Center

    Tan, Mei; Reich, Jodi; Hart, Lesley; Thuma, Philip E.; Grigorenko, Elena L.

    2014-01-01

    Generally accepted as universal, the construct of adaptive behavior differs in its manifestations across different cultures and settings. The Vineland-II (Sparrow et al. in "Vineland Adaptive Behavior Scales, Second edn." AGS Publishing, Circle Pines, MN, 2005) was translated into Chitonga and adapted to the setting of rural Southern…

  3. Aging behavior and life prediction of graphite composites

    NASA Technical Reports Server (NTRS)

    Ramohalli, Kumar; Raasch, David

    1989-01-01

    This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

  4. The behavior of delaminations in composite materials - experimental results

    NASA Astrophysics Data System (ADS)

    Chermoshentseva, A. S.; Pokrovskiy, A. M.; Bokhoeva, L. A.

    2016-02-01

    Delamination is one of the most common failure modes of composite materials. It may occur as a consequence of imperfections in the production process or the effects of external factors during the operational life of the composite laminates, such as the impact by foreign objects. This paper presents the results of mechanical tests and the optimum degrees of filling the composite materials (CM) with hydrophobic powder (Tarkosil T-20) depending on the latter mass concentration. The results present test samples of the CM with the underlying interlayer defects. The samples were fabricated of twenty-ply pre-preg (fiberglass or carbon fiber). The industrial grade glass is T-25 (VM) specification 6-11-380-76. The composite materials have nanosized additives in structure. The volume concentration of nanopowders is varying from 0.1% to 0.5%. This kind of research has been done for the first time.

  5. High Strain Rate Behavior of Polymer Matrix Composites Analyzed

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2001-01-01

    Procedures for modeling the high-speed impact of composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. To characterize and validate material models that could be used in the design of impactresistant engine cases, researchers must obtain material data over a wide variety of strain rates. An experimental program has been carried out through a university grant with the Ohio State University to obtain deformation data for a representative polymer matrix composite for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used to characterize and validate a constitutive model that was developed at the NASA Glenn Research Center.

  6. Statistical characterization of the fatigue behavior of composite lamina

    NASA Technical Reports Server (NTRS)

    Yang, J. N.; Jones, D. L.

    1979-01-01

    A theoretical model was developed to predict statistically the effects of constant and variable amplitude fatigue loadings on the residual strength and fatigue life of composite lamina. The parameters in the model were established from the results of a series of static tensile tests and a fatigue scan and a number of verification tests were performed. Abstracts for two other papers on the effect of load sequence on the statistical fatigue of composites are also presented.

  7. Distributed recurrent neural forward models with synaptic adaptation and CPG-based control for complex behaviors of walking robots

    PubMed Central

    Dasgupta, Sakyasingha; Goldschmidt, Dennis; Wörgötter, Florentin; Manoonpong, Poramate

    2015-01-01

    Walking animals, like stick insects, cockroaches or ants, demonstrate a fascinating range of locomotive abilities and complex behaviors. The locomotive behaviors can consist of a variety of walking patterns along with adaptation that allow the animals to deal with changes in environmental conditions, like uneven terrains, gaps, obstacles etc. Biological study has revealed that such complex behaviors are a result of a combination of biomechanics and neural mechanism thus representing the true nature of embodied interactions. While the biomechanics helps maintain flexibility and sustain a variety of movements, the neural mechanisms generate movements while making appropriate predictions crucial for achieving adaptation. Such predictions or planning ahead can be achieved by way of internal models that are grounded in the overall behavior of the animal. Inspired by these findings, we present here, an artificial bio-inspired walking system which effectively combines biomechanics (in terms of the body and leg structures) with the underlying neural mechanisms. The neural mechanisms consist of (1) central pattern generator based control for generating basic rhythmic patterns and coordinated movements, (2) distributed (at each leg) recurrent neural network based adaptive forward models with efference copies as internal models for sensory predictions and instantaneous state estimations, and (3) searching and elevation control for adapting the movement of an individual leg to deal with different environmental conditions. Using simulations we show that this bio-inspired approach with adaptive internal models allows the walking robot to perform complex locomotive behaviors as observed in insects, including walking on undulated terrains, crossing large gaps, leg damage adaptations, as well as climbing over high obstacles. Furthermore, we demonstrate that the newly developed recurrent network based approach to online forward models outperforms the adaptive neuron forward models

  8. The Influence of Temperature on Frictional Behavior of Plasma-Sprayed NiAl-Cr2O3 Based Self-Adaptive Nanocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Ramazani, M.; Ashrafizadeh, F.; Mozaffarinia, R.

    2013-10-01

    Frictional behavior of nano and hybrid-structured NiAl-Cr2O3-Ag-CNT-WS2 adaptive self-lubricant coatings was evaluated at a range of temperatures, from room temperature to 700 °C. For this purpose, hybrid structured (HS) and nanostructured (NS) composite powders with the same nominal compositions were prepared by spray drying and heat treatment techniques. A series of HS and NS coating samples were deposited on steel substrate by an atmospheric plasma spraying process. The tribological behavior of both coatings was studied from room temperature to 700 °C at 100° intervals using a custom designed high temperature wear test machine. Scanning electron microscopy was employed for the evaluation of the composite coatings and worn surfaces. Experimental results indicated that the hybrid coating had inferior tribological properties when compared to the nanostructured coating, showing the attractive frictional behavior on the basis of low friction and high wear resistance; the NS coating possessed a more stable friction coefficient in the temperature range of 25-700 °C against alumina counterface. Microstructural examinations revealed more uniformity in NS plasma-sprayed coatings.

  9. The aqueous corrosion behavior of technetium - Alloy and composite materials

    SciTech Connect

    Jarvinen, G.; Kolman, D.; Taylor, C.; Goff, G.; Cisneros, M.; Mausolf, E.; Poineau, F.; Koury, D.; Czerwinski, K.

    2013-07-01

    Metal waste forms are under study as possible disposal forms for technetium and other fission products. The alloying of Tc is desirable to reduce the melting point of the Tc-containing metal waste form and potentially improve its corrosion resistance. Technetium-nickel composites were made by mixing the two metal powders and pressing the mixture to make a pellet. The as-pressed composite materials were compared to sintered composites and alloys of identical composition in electrochemical corrosion tests. As-pressed samples were not robust enough for fine polishing and only a limited number of corrosion tests were performed. Alloys and composites with 10 wt% Tc appear to be more corrosion resistant at open circuit than the individual components based on linear polarization resistance and polarization data. The addition of 10 wt% Tc to Ni appears beneficial at open circuit, but detrimental upon anodic polarization. Qualitatively, the polarizations of 10 wt% Tc alloys and composites appear like crude addition of Tc plus Ni. The 1 wt% Tc alloys behave like pure Ni, but some effect of Tc is seen upon polarization. Cathodic polarization of Tc by Ni appears feasible based on open circuit potential measurements, however, zero resistance ammetry and solution measurements are necessary to confirm cathodic protection.

  10. Health problem behaviors in Iranian adolescents: a study of cross-cultural adaptation, reliability, and validity

    PubMed Central

    Eslami, Ahmad Ali; Ghofranipour, Fazlollah; Bonab, Bagher Ghobari; Zadeh, Davood Shojaei; Shokravi, Farkhondeh Amin; Tabatabaie, Mahmoud Ghazi

    2010-01-01

    BACKGROUND: The main purpose of this study was to assess the factorial validity and reliability of the Iranian versions of the personality and behavior system scales (49 items) of the AHDQ (The Adolescent Health and Development Questionnaire) and interrelations among them based on Jessor’s PBT (Problem Behavior Theory). METHODS: A multi-staged approach was employed. The cross-cultural adaptation was performed according to the internationally recommended methodology, using the following guidelines: translation, back-translation, revision by a committee, and pretest. After modifying and identifying of the best items, a cross-sectional study was conducted to assess the psychometric properties of Persian version using calibration and validation samples of adolescents. Also 113 of them completed it again two weeks later for stability. RESULTS: The findings of the exploratory factor analysis suggested that the 7-factor solution with low self concept, emotional distress, general delinquency, cigarette, hookah, alcohol, and hard drugs use provided a better fitting model. The α range for these identified factors was 0.69 to 0.94, the ICC range was 0.73 to 0.93, and there was a significant difference in mean scores for these instruments in compare between the male normative and detention adolescents. The first and second-order measurement models testing found good model fit for the 7-factor model. CONCLUSIONS: Factor analyses provided support of existence internalizing and externalizing problem behavior syndrome. With those qualifications, this model can be applied for studies among Persian adolescents. PMID:21526075

  11. Adaptive behavior for texture discrimination by the free-flying big brown bat, Eptesicus fuscus.

    PubMed

    Falk, Ben; Williams, Tameeka; Aytekin, Murat; Moss, Cynthia F

    2011-05-01

    This study examined behavioral strategies for texture discrimination by echolocation in free-flying bats. Big brown bats, Eptesicus fuscus, were trained to discriminate a smooth 16 mm diameter object (S+) from a size-matched textured object (S-), both of which were tethered in random locations in a flight room. The bat's three-dimensional flight path was reconstructed using stereo images from high-speed video recordings, and the bat's sonar vocalizations were recorded for each trial and analyzed off-line. A microphone array permitted reconstruction of the sonar beam pattern, allowing us to study the bat's directional gaze and inspection of the objects. Bats learned the discrimination, but performance varied with S-. In acoustic studies of the objects, the S+ and S- stimuli were ensonified with frequency-modulated sonar pulses. Mean intensity differences between S+ and S- were within 4 dB. Performance data, combined with analyses of echo recordings, suggest that the big brown bat listens to changes in sound spectra from echo to echo to discriminate between objects. Bats adapted their sonar calls as they inspected the stimuli, and their sonar behavior resembled that of animals foraging for insects. Analysis of sonar beam-directing behavior in certain trials clearly showed that the bat sequentially inspected S+ and S-. PMID:21246202

  12. Adaptive behavior for texture discrimination by the free-flying big brown bat, Eptesicus fuscus

    PubMed Central

    Falk, Ben; Williams, Tameeka; Aytekin, Murat

    2011-01-01

    This study examined behavioral strategies for texture discrimination by echolocation in free-flying bats. Big brown bats, Eptesicus fuscus, were trained to discriminate a smooth 16 mm diameter object (S+) from a size-matched textured object (S−), both of which were tethered in random locations in a flight room. The bat’s three-dimensional flight path was reconstructed using stereo images from high-speed video recordings, and the bat’s sonar vocalizations were recorded for each trial and analyzed off-line. A microphone array permitted reconstruction of the sonar beam pattern, allowing us to study the bat’s directional gaze and inspection of the objects. Bats learned the discrimination, but performance varied with S−. In acoustic studies of the objects, the S+ and S− stimuli were ensonified with frequency-modulated sonar pulses. Mean intensity differences between S+ and S− were within 4 dB. Performance data, combined with analyses of echo recordings, suggest that the big brown bat listens to changes in sound spectra from echo to echo to discriminate between objects. Bats adapted their sonar calls as they inspected the stimuli, and their sonar behavior resembled that of animals foraging for insects. Analysis of sonar beam-directing behavior in certain trials clearly showed that the bat sequentially inspected S+ and S−. PMID:21246202

  13. Responses of leaf traits to climatic gradients: adaptive variation versus compositional shifts

    NASA Astrophysics Data System (ADS)

    Meng, T.-T.; Wang, H.; Harrison, S. P.; Prentice, I. C.; Ni, J.; Wang, G.

    2015-09-01

    , but Parea increased with temperature. Although the adaptive nature of many of these trait-climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits. Finally, models should take account of the diversity of trait values that is found in all sites and PFTs, representing the "pool" of variation that is locally available for the natural adaptation of ecosystem function to environmental change.

  14. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    PubMed Central

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  15. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  16. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-04-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  17. Characterization of mode II fracture behavior in fiber-reinforced ceramic composite utilizing laser interferometry

    SciTech Connect

    Mall, S.; Truskowski, J.W. USAF, Wright-Patterson AFB, OH )

    1992-09-01

    A test technique to characterize the mode II fracture behavior in fiber-reinforced ceramic composites utilizing laser interferometry was developed. This was demonstrated by measuring the mode II critical strain energy release rate at room temperature. The present study used the silicon-carbide-fiber/glass-ceramic matrix composite system. 13 refs.

  18. A parameter study on the biaxial behavior of flexible fabric composites

    SciTech Connect

    Mitra, A.; Luo, S.Y.

    1994-12-31

    The nonlinear behavior of flexible fabric composite under large bi-axial deformation is attributed by many factors, including the ratio of biaxial loads, the crimps of the yarns, the thickness of the composite, and the properties of the yarn and the matrix. A parameter study has been conducted to evaluate the significance of these factors on the stress-strain relations of flexible fabric composites.

  19. Mechanical behavior of reactively hot-pressed aluminide matrix composite

    SciTech Connect

    Inoue, M.; Suganuma, K.; Niihara, K.

    1997-12-31

    FeAl and Ni{sub 3}Al matrix composites containing various fine particles were fabricated successfully by reactive hot-pressing. The strength and the fracture toughness of these composites at ambient temperatures were evaluated. The addition of {beta}-SiC particles was effective for strengthening of the Fe-40at%Al matrix, however, an extreme decrease of fracture toughness occurred due to the suppression of stress relaxation effect by plastic deformation at a crack tip. The fracture toughness of the reactively hot pressed Fe-40at%Al and its composites was also affected by the environmental embrittlement effect. TiB{sub 2} and ZrB{sub 2} particles in the Fe-40at%Al matrix composites were clarified to play a role in the reduction of the environmental effect. For the Ni-25at%Al matrix, higher flexural strength was achieved by the addition of TiB{sub 2}, TiC and TiN particles. TiB{sub 2} particles reacted with the matrix during hot-pressing. The Ni-25at%Al/TiB{sub 2} composite had a fracture strength of 1.5 GPa in spite of large grain size of the matrix. TiC and TiN were the best choices as effective reinforcing materials for the Ni{sub 3}Al matrix among the chemical compatible ones.

  20. Fracture behavior of 20% Nb particulate reinforced alumina composite

    SciTech Connect

    Lane, S.; Biner, S.B.; Buck, O.

    1993-11-01

    The composites consist of alumina matrix with 0.05 wt % MgO and 20 Vol % Nb with an average particle size of 30 to 100 microns produced by dry mixing and sintering to near their theoretical densities. Fracture toughness tests were carried out in three point bending on chevron notched samples. Results indicate that R-curve of the composites exhibited more than 300% increase in crack growth resistance compared to crack growth resistance of alumina produced with the identical procedures. Crack growth resistance curve of the composites increased with increasing Nb particle size. Metallorgraph indicated that failure of Nb particles in crack path ranges from full interface separation without any significant deformation of Nb particles to cleavage failure without any evidence of interface separation.

  1. Friction and wear behavior of graphite fiber reinforced polyimide composites

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.; Sliney, H. E.

    1977-01-01

    The friction and wear rate characteristics of 50/50 (weight per cent) graphite fiber-polyimide composites were studied by sliding metallic hemispherically tipped riders against disks made from the composites. Two different polyimides and two different graphite fibers were evaluated. Also studied were such variables as the effect of adding 10 per cent weight additions of powdered (CF-1.1)n, CdI2, or CdO, the effect of moisture in an air atmosphere, the effect of temperature, and the effect of different sliding speeds. In general, wear to the metallic riders was negligible and composite wear increased at a constant rate as a function of number of sliding cycles.

  2. Effects of culturally adapted parent management training on Latino youth behavioral health outcomes.

    PubMed

    Martinez, Charles R; Eddy, J Mark

    2005-10-01

    A randomized experimental test of the implementation feasibility and the efficacy of a culturally adapted Parent Management Training intervention was conducted with a sample of 73 Spanish-speaking Latino parents with middle-school-aged youth at risk for problem behaviors. Intervention feasibility was evaluated through weekly parent satisfaction ratings, intervention participation and attendance, and overall program satisfaction. Intervention effects were evaluated by examining changes in parenting and youth adjustment for the intervention and control groups between baseline and intervention termination approximately 5 months later. Findings provided strong evidence for the feasibility of delivering the intervention in a larger community context. The intervention produced benefits in both parenting outcomes (i.e., general parenting, skill encouragement, overall effective parenting) and youth outcomes (i.e., aggression, externalizing, likelihood of smoking and use of alcohol, marijuana, and other drugs). Differential effects of the intervention were based on youth nativity status. PMID:16287384

  3. Early Nonparental Care and Social Behavior in Elementary School: Support for a Social Group Adaptation Hypothesis.

    PubMed

    Pingault, Jean-Baptiste; Tremblay, Richard E; Vitaro, Frank; Japel, Christa; Boivin, Michel; Côté, Sylvana M

    2015-01-01

    This study examined the contribution of nonparental child-care services received during the preschool years to the development of social behavior between kindergarten and the end of elementary school with a birth cohort from Québec, Canada (N = 1,544). Mothers reported on the use of child-care services, while elementary school teachers rated children's shyness, social withdrawal, prosociality, opposition, and aggression. Children who received nonparental child-care services were less shy, less socially withdrawn, more oppositional, and more aggressive at school entry (age 6 years). However, these differences disappeared during elementary school as children who received exclusive parental care caught up with those who received nonparental care services. This "catch-up" effect from the perspective of children's adaptation to the social group is discussed. PMID:26358177

  4. Comparative Cost Analysis of Sequential, Adaptive, Behavioral, Pharmacological, and Combined Treatments for Childhood ADHD.

    PubMed

    Page, Timothy F; Pelham, William E; Fabiano, Gregory A; Greiner, Andrew R; Gnagy, Elizabeth M; Hart, Katie C; Coxe, Stefany; Waxmonsky, James G; Foster, E Michael; Pelham, William E

    2016-01-01

    We conducted a cost analysis of the behavioral, pharmacological, and combined interventions employed in a sequential, multiple assignment, randomized, and adaptive trial investigating the sequencing and enhancement of treatment for children with attention deficit hyperactivity disorder (ADHD; Pelham et al., 201X; N = 146, 76% male, 80% Caucasian). The quantity of resources expended on each child's treatment was determined from records that listed the type, date, location, persons present, and duration of all services provided. The inputs considered were the amount of physician time, clinician time, paraprofessional time, teacher time, parent time, medication, and gasoline. Quantities of these inputs were converted into costs in 2013 USD using national wage estimates from the Bureau of Labor Statistics, the prices of 30-day supplies of prescription drugs from the national Express Scripts service, and mean fuel prices from the Energy Information Administration. Beginning treatment with a low-dose/intensity regimen of behavior modification (large-group parent training) was less costly for a school year of treatment ($961) than beginning treatment with a low dose of stimulant medication ($1,669), regardless of whether the initial treatment was intensified with a higher "dose" or if the other modality was added. Outcome data from the parent study (Pelham et al., 201X) found equivalent or superior outcomes for treatments beginning with low-intensity behavior modification compared to intervention beginning with medication. Combined with the present analyses, these findings suggest that initiating treatment with behavior modification rather than medication is the more cost-effective option for children with ADHD. PMID:26808137

  5. Behavioral buffering of global warming in a cold-adapted lizard.

    PubMed

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-07-01

    Alpine lizards living in restricted areas might be particularly sensitive to climate change. We studied thermal biology of Iberolacerta cyreni in high mountains of central Spain. Our results suggest that I. cyreni is a cold-adapted thermal specialist and an effective thermoregulator. Among ectotherms, thermal specialists are more threatened by global warming than generalists. Alpine lizards have no chance to disperse to new suitable habitats. In addition, physiological plasticity is unlikely to keep pace with the expected rates of environmental warming. Thus, lizards might rely on their behavior in order to deal with ongoing climate warming. Plasticity of thermoregulatory behavior has been proposed to buffer the rise of environmental temperatures. Therefore, we studied the change in body and environmental temperatures, as well as their relationships, for I. cyreni between the 1980s and 2012. Air temperatures have increased more than 3.5°C and substrate temperatures have increased by 6°C in the habitat of I. cyreni over the last 25 years. However, body temperatures of lizards have increased less than 2°C in the same period, and the linear relationship between body and environmental temperatures remains similar. These results show that alpine lizards are buffering the potential impact of the increase in their environmental temperatures, most probably by means of their behavior. Body temperatures of I. cyreni are still cold enough to avoid any drop in fitness. Nonetheless, if warming continues, behavioral buffering might eventually become useless, as it would imply spending too much time in shelter, losing feeding, and mating opportunities. Eventually, if body temperature exceeds the thermal optimum in the near future, fitness would decrease abruptly. PMID:27386098

  6. Laminated metals composites fracture and ballistic impact behavior

    SciTech Connect

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D.; Wadsworth, J.

    1998-01-20

    Recent advances in the fracture and ballistic impact response of laminated metal composites (LMCs) are reviewed. The laminate structure can provide significant improvements to these properties relative to the component materials. Typical fracture and ballistic impact properties in LMCs are illustrated for systems containing Al alloys and Al matrix composites. The unique mechanisms operating in a layered structure that contribute to fracture or ballistic impact resistance are discussed. The influence of laminate architecture, component material properties and interface strength on mechanisms and properties are briefly reviewed for these Al-based LMCs.

  7. Culturally Adapted Cognitive Behavioral Therapy for Depressed Chinese Americans: A Randomized Controlled Trial

    PubMed Central

    Hwang, Wei-Chin; Myers, Hector; Chiu, Eddie; Mak, Elsie; Butner, Jonathan; Fujimoto, Ken; Wood, Jeff; Miranda, Jeanne

    2015-01-01

    Objective No randomized controlled trials (RCTs) for adults have tested the effectiveness of a well-specified psychotherapy compared with a culturally adapted version of the same treatment. This study evaluates the effectiveness of cognitive behavioral therapy (CBT) and culturally adapted CBT (CA-CBT) in treating depressed Chinese American adults. Methods This was a RCT that treated 50 Chinese Americans who met criteria for major depression and sought treatment at community mental health clinics. Participants were screened beginning September 2008, with the last assessment conducted in March 2011. Participants were randomly assigned to 12 sessions of CBT or CA-CBT. Stratified randomization was used for patients who were on and not on antidepressants when they first came to the clinic, and the study did not influence regular prescription practices. The primary outcomes were dropout rates and the Hamilton Depression Rating Scale measured at baseline, session 4, session 8, and session 12. Results Participants in CA-CBT evidenced a greater overall decrease in depressive symptoms than those in CBT, but depression rates remained similarly high at week 12. Differences in dropout rates approached, but did not meet statistical significance (7% CA-CBT and 26% CBT). Conclusions Chinese Americans entered this study with very severe depression. Participants in both CBT and CA-CBT evidenced significant decreases in depressive symptoms, but the majority did not reach remission. Results suggest that these short-term treatments were not sufficient to address such severe depression and that more intensive and longer treatments may be needed. Results also indicate that cultural adaptations may confer additional treatment benefits. PMID:26129996

  8. The reliability and validity of the Test of Adaptive Behavior in Schizophrenia (TABS).

    PubMed

    Velligan, Dawn I; Diamond, Pamela; Glahn, David C; Ritch, Janice; Maples, Natalie; Castillo, Desiree; Miller, Alexander L

    2007-05-30

    Performance-based tests of functional capacity are important to utilize in schizophrenia where global measures may underestimate community functioning in the context of impoverished environments and disincentives to return to work. The Test of Adaptive Behavior in Schizophrenia (TABS) is a performance-based measure of adaptive functioning designed to address limitations of other available measures including limited assessment of the ability to initiate and of the ability to identify problems that occur in the course of performing functional activities. The TABS and a variety of symptom, functional outcome, and cognitive measures were administered to 264 outpatients with schizophrenia/schizoaffective disorders at an initial assessment. At 3 months, 110 subjects received a follow-up assessment. Results indicated that the TABS had very good test-retest reliability (0.80) and inter-item consistency (0.84). Moreover, TABS scores were moderately to strongly correlated with other measures of functional outcome, negative symptoms and neuropsychological test scores (convergent validity). Measures of positive symptoms were not found to be related to TABS performance (discriminate validity). The data provide preliminary evidence for the reliability and validity of the TABS. Further studies of the psychometric properties of the TABS including those examining the sensitivity of the TABS to treatments with different pharmacological agents or psychosocial treatments are encouraged. PMID:17379319

  9. Cognitive Adaptations for n-person Exchange: The Evolutionary Roots of Organizational Behavior

    PubMed Central

    Tooby, John; Cosmides, Leda; Price, Michael E.

    2013-01-01

    Organizations are composed of stable, predominantly cooperative interactions or n-person exchanges. Humans have been engaging in n-person exchanges for a great enough period of evolutionary time that we appear to have evolved a distinct constellation of species-typical mechanisms specialized to solve the adaptive problems posed by this form of social interaction. These mechanisms appear to have been evolutionarily elaborated out of the cognitive infrastructure that initially evolved for dyadic exchange. Key adaptive problems that these mechanisms are designed to solve include coordination among individuals, and defense against exploitation by free riders. Multi-individual cooperation could not have been maintained over evolutionary time if free riders reliably benefited more than contributors to collective enterprises, and so outcompeted them. As a result, humans evolved mechanisms that implement an aversion to exploitation by free riding, and a strategy of conditional cooperation, supplemented by punitive sentiment towards free riders. Because of the design of these mechanisms, how free riding is treated is a central determinant of the survival and health of cooperative organizations. The mapping of the evolved psychology of n-party exchange cooperation may contribute to the construction of a principled theoretical foundation for the understanding of human behavior in organizations. PMID:23814325

  10. Antenatal Glucocorticoid Treatment Induces Adaptations in Adult Midbrain Dopamine Neurons, which Underpin Sexually Dimorphic Behavioral Resilience

    PubMed Central

    Virdee, Kanwar; McArthur, Simon; Brischoux, Frédéric; Caprioli, Daniele; Ungless, Mark A; Robbins, Trevor W; Dalley, Jeffrey W; Gillies, Glenda E

    2014-01-01

    We demonstrated previously that antenatal glucocorticoid treatment (AGT, gestational days 16–19) altered the size and organization of the adult rat midbrain dopaminergic (DA) populations. Here we investigated the consequences of these AGT-induced cytoarchitectural disturbances on indices of DA function in adult rats. We show that in adulthood, enrichment of striatal DA fiber density paralleled AGT-induced increases in the numbers of midbrain DA neurons, which retained normal basal electrophysiological properties. This was co-incident with changes in (i) striatal D2-type receptor levels (increased, both sexes); (ii) D1-type receptor levels (males decreased; females increased); (iii) DA transporter levels (males increased; females decreased) in striatal regions; and (iv) amphetamine-induced mesolimbic DA release (males increased; females decreased). However, despite these profound, sexually dimorphic changes in markers of DA neurotransmission, in-utero glucocorticoid overexposure had a modest or no effect on a range of conditioned and unconditioned appetitive behaviors known to depend on mesolimbic DA activity. These findings provide empirical evidence for enduring AGT-induced adaptive mechanisms within the midbrain DA circuitry, which preserve some, but not all, functions, thereby casting further light on the vulnerability of these systems to environmental perturbations. Furthermore, they demonstrate these effects are achieved by different, often opponent, adaptive mechanisms in males and females, with translational implications for sex biases commonly found in midbrain DA-associated disorders. PMID:23929547

  11. Children with Williams syndrome: Developmental trajectories for intellectual abilities, vocabulary abilities, and adaptive behavior.

    PubMed

    Mervis, Carolyn B; Pitts, C Holley

    2015-06-01

    To examine longitudinal trajectories of intellectual abilities, single-word vocabulary abilities, and adaptive behavior for 76 children with Williams syndrome (WS) aged 4-15 years, we compared their standard scores (SSs) at two time points approximately 3 years apart on the same standardized measures. At the group level, mean SS declined significantly for 8 of the 12 measures and showed a slight (nonsignificant) increase or decrease for 4 measures. However, for most measures significant changes in SS were found for only a small proportion of the children, with some children evidencing significant declines and a smaller proportion evidencing significant increases. Significant SS changes were most common for adaptive behavior. For all measures, the mean magnitude of SS change was smaller for older children (>7.5 years at Time 1) than for younger children (<7.5 years at Time 1). Furthermore, correlations between Time 1 and Time 2 SSs were larger for the older cohort than for the younger cohort, indicating that SS stability was greater for older children than for younger children. Although mean SSs declined for most measures, indicating that children with WS as a group were not making the expected amount of progress relative to their general population peers who earned the same SS at Time 1, there was little evidence either of regression (loss of skills) or stagnation (failure to increase raw scores). The relations of these results to those of previous smaller-sample longitudinal studies of children with WS and the implications of the findings are considered. PMID:25989316

  12. Numerical Relations and Skill Level Constrain Co-Adaptive Behaviors of Agents in Sports Teams

    PubMed Central

    Silva, Pedro; Travassos, Bruno; Vilar, Luís; Aguiar, Paulo; Davids, Keith; Araújo, Duarte; Garganta, Júlio

    2014-01-01

    Similar to other complex systems in nature (e.g., a hunting pack, flocks of birds), sports teams have been modeled as social neurobiological systems in which interpersonal coordination tendencies of agents underpin team swarming behaviors. Swarming is seen as the result of agent co-adaptation to ecological constraints of performance environments by collectively perceiving specific possibilities for action (affordances for self and shared affordances). A major principle of invasion team sports assumed to promote effective performance is to outnumber the opposition (creation of numerical overloads) during different performance phases (attack and defense) in spatial regions adjacent to the ball. Such performance principles are assimilated by system agents through manipulation of numerical relations between teams during training in order to create artificially asymmetrical performance contexts to simulate overloaded and underloaded situations. Here we evaluated effects of different numerical relations differentiated by agent skill level, examining emergent inter-individual, intra- and inter-team coordination. Groups of association football players (national – NLP and regional-level – RLP) participated in small-sided and conditioned games in which numerical relations between system agents were manipulated (5v5, 5v4 and 5v3). Typical grouping tendencies in sports teams (major ranges, stretch indices, distances of team centers to goals and distances between the teams' opposing line-forces in specific team sectors) were recorded by plotting positional coordinates of individual agents through continuous GPS tracking. Results showed that creation of numerical asymmetries during training constrained agents' individual dominant regions, the underloaded teams' compactness and each team's relative position on-field, as well as distances between specific team sectors. We also observed how skill level impacted individual and team coordination tendencies. Data revealed

  13. Numerical relations and skill level constrain co-adaptive behaviors of agents in sports teams.

    PubMed

    Silva, Pedro; Travassos, Bruno; Vilar, Luís; Aguiar, Paulo; Davids, Keith; Araújo, Duarte; Garganta, Júlio

    2014-01-01

    Similar to other complex systems in nature (e.g., a hunting pack, flocks of birds), sports teams have been modeled as social neurobiological systems in which interpersonal coordination tendencies of agents underpin team swarming behaviors. Swarming is seen as the result of agent co-adaptation to ecological constraints of performance environments by collectively perceiving specific possibilities for action (affordances for self and shared affordances). A major principle of invasion team sports assumed to promote effective performance is to outnumber the opposition (creation of numerical overloads) during different performance phases (attack and defense) in spatial regions adjacent to the ball. Such performance principles are assimilated by system agents through manipulation of numerical relations between teams during training in order to create artificially asymmetrical performance contexts to simulate overloaded and underloaded situations. Here we evaluated effects of different numerical relations differentiated by agent skill level, examining emergent inter-individual, intra- and inter-team coordination. Groups of association football players (national--NLP and regional-level--RLP) participated in small-sided and conditioned games in which numerical relations between system agents were manipulated (5v5, 5v4 and 5v3). Typical grouping tendencies in sports teams (major ranges, stretch indices, distances of team centers to goals and distances between the teams' opposing line-forces in specific team sectors) were recorded by plotting positional coordinates of individual agents through continuous GPS tracking. Results showed that creation of numerical asymmetries during training constrained agents' individual dominant regions, the underloaded teams' compactness and each team's relative position on-field, as well as distances between specific team sectors. We also observed how skill level impacted individual and team coordination tendencies. Data revealed emergence of

  14. Children with Williams Syndrome: Developmental Trajectories for Intellectual Abilities, Vocabulary Abilities, and Adaptive Behavior

    PubMed Central

    Mervis, Carolyn B.; Pitts, C. Holley

    2016-01-01

    To examine longitudinal trajectories of intellectual abilities, single-word vocabulary abilities, and adaptive behavior for 76 children with Williams syndrome (WS) aged 4 – 15 years, we compared their standard scores (SSs) at two time points approximately 3 years apart on the same standardized measures. At the group level, mean SS declined significantly for 8 of the 12 measures and showed a slight (nonsignificant) increase or decrease for 4 measures. However, for most measures significant changes in SS were found for only a small proportion of the children, with some children evidencing significant declines and a smaller proportion evidencing significant increases. Significant SS changes were most common for adaptive behavior. For all measures, the mean magnitude of SS change was smaller for older children (> 7.5 years at Time 1) than for younger children (< 7.5 years at Time 1). Furthermore, correlations between Time 1 and Time 2 SSs were larger for the older cohort than for the younger cohort, indicating that SS stability was greater for older children than for younger children. Although mean SSs declined for most measures, indicating that children with WS as a group were not making the expected amount of progress relative to their general population peers who earned the same SS at Time 1, there was little evidence either of regression (loss of skills) or stagnation (failure to increase raw scores). The relations of these results to those of previous smaller-sample longitudinal studies of children with WS and the implications of the findings are considered. PMID:25989316

  15. Executive Function Predicts Adaptive Behavior in Children with Histories of Heavy Prenatal Alcohol Exposure and Attention Deficit/Hyperactivity Disorder

    PubMed Central

    Ware, Ashley L.; Crocker, Nicole; O’Brien, Jessica W.; Deweese, Benjamin N.; Roesch, Scott C.; Coles, Claire D.; Kable, Julie A.; May, Philip A.; Kalberg, Wendy O.; Sowell, Elizabeth R.; Jones, Kenneth Lyons; Riley, Edward P.; Mattson, Sarah N.

    2011-01-01

    Purpose of Study Prenatal exposure to alcohol often results in disruption to discrete cognitive and behavioral domains, including executive function (EF) and adaptive functioning. In the current study, the relation between these two domains was examined in children with histories of heavy prenatal alcohol exposure, non-exposed children with a diagnosis of attention-deficit/hyperactivity disorder (ADHD), and typically developing controls. Methods As part of a multisite study, three groups of children (8-18y, M = 12.10) were tested: children with histories of heavy prenatal alcohol exposure (ALC, N=142), non-exposed children with ADHD (ADHD, N=82), and typically developing controls (CON, N=133) who did not have ADHD or a history of prenatal alcohol exposure. Children completed subtests of the Delis-Kaplan Executive Function System (D-KEFS) and their primary caregivers completed the Vineland Adaptive Behavior Scales-II (VABS). Data were analyzed using regression analyses. Results Analyses showed that EF measures were predictive of adaptive abilities and significant interactions between D-KEFS measures and group were present. For the ADHD group, the relation between adaptive abilities and EF was more general, with three of the four EF measures showing a significant relation with adaptive score. In contrast, for the ALC group, this relation was specific to the nonverbal EF measures. In the CON group, performance on EF tasks did not predict adaptive scores over the influence of age. Conclusion These results support prior research in ADHD suggesting that EF deficits are predictive of poorer adaptive behavior and extend this finding to include children with heavy prenatal exposure to alcohol. However, the relation between EF and adaptive ability differed by group, suggesting unique patterns of abilities in these children. These results provide enhanced understanding of adaptive deficits in these populations, as well as demonstrate the ecological validity of laboratory

  16. Toward a Theory of Adaptive Transfer: Expanding Disciplinary Discussions of "Transfer" in Second-Language Writing and Composition Studies

    ERIC Educational Resources Information Center

    DePalma, Michael-John; Ringer, Jeffrey M.

    2011-01-01

    In this paper, we argue that discussions of transfer in L2 writing and composition studies have focused primarily on the reuse of past learning and thus have not adequately accounted for the adaptation of learned writing knowledge in unfamiliar situations. In an effort to expand disciplinary discussions of transfer in L2 writing and composition…

  17. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  18. Anomalous swelling behavior of FM 5055 carbon phenolic composite

    NASA Technical Reports Server (NTRS)

    Stokes, E. H.

    1992-01-01

    The swelling response of a typical carbon phenolic composite was measured in the three primary material directions. The data obtained sugrest that at low and high relative humidities the incremental increase in moisture absorption can be attributed primarily to the resin. At intermediate relative humidities, the water is moving largely into the carbonized fibers.

  19. Composite Adaptive Fuzzy Output Feedback Control Design for Uncertain Nonlinear Strict-Feedback Systems With Input Saturation.

    PubMed

    Li, Yongming; Tong, Shaocheng; Li, Tieshan

    2015-10-01

    In this paper, a composite adaptive fuzzy output-feedback control approach is proposed for a class of single-input and single-output strict-feedback nonlinear systems with unmeasured states and input saturation. Fuzzy logic systems are utilized to approximate the unknown nonlinear functions, and a fuzzy state observer is designed to estimate the unmeasured states. By utilizing the designed fuzzy state observer, a serial-parallel estimation model is established. Based on adaptive backstepping dynamic surface control technique and utilizing the prediction error between the system states observer model and the serial-parallel estimation model, a new fuzzy controller with the composite parameters adaptive laws are developed. It is proved that all the signals of the closed-loop system are bounded and the system output can follow the given bounded reference signal. A numerical example and simulation comparisons with previous control methods are provided to show the effectiveness of the proposed approach. PMID:25438335

  20. Composite adaptive control of belt polishing force for aero-engine blade

    NASA Astrophysics Data System (ADS)

    Zhsao, Pengbing; Shi, Yaoyao

    2013-09-01

    The existing methods for blade polishing mainly focus on robot polishing and manual grinding. Due to the difficulty in high-precision control of the polishing force, the blade surface precision is very low in robot polishing, in particular, quality of the inlet and exhaust edges can not satisfy the processing requirements. Manual grinding has low efficiency, high labor intensity and unstable processing quality, moreover, the polished surface is vulnerable to burn, and the surface precision and integrity are difficult to ensure. In order to further improve the profile accuracy and surface quality, a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed, which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together. By the mode decision-making mechanism, Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value, and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision. Based on the mathematical model of the force-exerting mechanism, simulation analysis is implemented on DSCAC. Simulation results show that the output polishing force can better track the given signal. Finally, the blade polishing experiments are carried out on the designed polishing equipment. Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility, valve dead-time effect, valve nonlinear flow, cylinder friction, measurement noise and other interference on the control precision of polishing force, which has high control precision, strong robustness, strong anti-interference ability and other advantages compared with MRACFNN. The proposed research achieves high-precision control of the polishing force, effectively improves the blade machining precision and surface consistency, and

  1. A study of an adaptive replication framework for orchestrated composite web services.

    PubMed

    Mohamed, Marwa F; Elyamany, Hany F; Nassar, Hamed M

    2013-01-01

    Replication is considered one of the most important techniques to improve the Quality of Services (QoS) of published Web Services. It has achieved impressive success in managing resource sharing and usage in order to moderate the energy consumed in IT environments. For a robust and successful replication process, attention should be paid to suitable time as well as the constraints and capabilities in which the process runs. The replication process is time-consuming since outsourcing some new replicas into other hosts is lengthy. Furthermore, nowadays, most of the business processes that might be implemented over the Web are composed of multiple Web services working together in two main styles: Orchestration and Choreography. Accomplishing a replication over such business processes is another challenge due to the complexity and flexibility involved. In this paper, we present an adaptive replication framework for regular and orchestrated composite Web services. The suggested framework includes a number of components for detecting unexpected and unhappy events that might occur when consuming the original published web services including failure or overloading. It also includes a specific replication controller to manage the replication process and select the best host that would encapsulate a new replica. In addition, it includes a component for predicting the incoming load in order to decrease the time needed for outsourcing new replicas, enhancing the performance greatly. A simulation environment has been created to measure the performance of the suggested framework. The results indicate that adaptive replication with prediction scenario is the best option for enhancing the performance of the replication process in an online business environment. PMID:24255826

  2. Ammonia sensing behaviors of TiO2-PANI/PA6 composite nanofibers.

    PubMed

    Wang, Qingqing; Dong, Xianjun; Pang, Zengyuan; Du, Yuanzhi; Xia, Xin; Wei, Qufu; Huang, Fenglin

    2012-01-01

    Titanium dioxide-polyaniline/polyamide 6 (TiO(2)-PANI/PA6) composite nanofibers were prepared by in situ polymerization of aniline in the presence of PA6 nanofibers and a sputtering-deposition process with a high purity titanium sputtering target. TiO(2)-PANI/PA6 composite nanofibers and PANI/PA6 composite nanofibers were fabricated for ammonia gas sensing. The ammonia sensing behaviors of the sensors were examined at room temperature. All the results indicated that the ammonia sensing property of TiO(2)-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO(2)-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO(2) had a great influence on both the morphology and the sensing property of TiO(2)-PANI/PA6 composite nanofibers. PMID:23235446

  3. Multi-optimization Criteria-based Robot Behavioral Adaptability and Motion Planning

    SciTech Connect

    Pin, Francois G.

    2002-06-01

    Robotic tasks are typically defined in Task Space (e.g., the 3-D World), whereas robots are controlled in Joint Space (motors). The transformation from Task Space to Joint Space must consider the task objectives (e.g., high precision, strength optimization, torque optimization), the task constraints (e.g., obstacles, joint limits, non-holonomic constraints, contact or tool task constraints), and the robot kinematics configuration (e.g., tools, type of joints, mobile platform, manipulator, modular additions, locked joints). Commercially available robots are optimized for a specific set of tasks, objectives and constraints and, therefore, their control codes are extremely specific to a particular set of conditions. Thus, there exist a multiplicity of codes, each handling a particular set of conditions, but none suitable for use on robots with widely varying tasks, objectives, constraints, or environments. On the other hand, most DOE missions and tasks are typically ''batches of one''. Attempting to use commercial codes for such work requires significant personnel and schedule costs for re-programming or adding code to the robots whenever a change in task objective, robot configuration, number and type of constraint, etc. occurs. The objective of our project is to develop a ''generic code'' to implement this Task-space to Joint-Space transformation that would allow robot behavior adaptation, in real time (at loop rate), to changes in task objectives, number and type of constraints, modes of controls, kinematics configuration (e.g., new tools, added module). Our specific goal is to develop a single code for the general solution of under-specified systems of algebraic equations that is suitable for solving the inverse kinematics of robots, is useable for all types of robots (mobile robots, manipulators, mobile manipulators, etc.) with no limitation on the number of joints and the number of controlled Task-Space variables, can adapt to real time changes in number and

  4. Functional adaptation of long bone extremities involves the localized ``tuning'' of the cortical bone composition; evidence from Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Buckley, Kevin; Kerns, Jemma G.; Birch, Helen L.; Gikas, Panagiotis D.; Parker, Anthony W.; Matousek, Pavel; Goodship, Allen E.

    2014-11-01

    In long bones, the functional adaptation of shape and structure occurs along the whole length of the organ. This study explores the hypothesis that adaptation of bone composition is also site-specific and that the mineral-to-collagen ratio of bone (and, thus, its mechanical properties) varies along the organ's length. Raman spectroscopy was used to map the chemical composition of long bones along their entire length in fine spatial resolution (1 mm), and then biochemical analysis was used to measure the mineral, collagen, water, and sulfated glycosaminoglycan content where site-specific differences were seen. The results show that the mineral-to-collagen ratio of the bone material in human tibiae varies by <5% along the mid-shaft but decreases by >10% toward the flared extremities of the bone. Comparisons with long bones from other large animals (horses, sheep, and deer) gave similar results with bone material composition changing across tens of centimeters. The composition of the bone apatite also varied with the phosphate-to-carbonate ratio decreasing toward the ends of the tibia. The data highlight the complexity of adaptive changes and raise interesting questions about the biochemical control mechanisms involved. In addition to their biological interest, the data provide timely information to researchers developing Raman spectroscopy as a noninvasive tool for measuring bone composition in vivo (particularly with regard to sampling and measurement protocol).

  5. Compression Behavior of Fluted-Core Composite Panels

    NASA Technical Reports Server (NTRS)

    Schultz, Marc R.; Oremont, Leonard; Guzman, J. Carlos; McCarville, Douglas; Rose, Cheryl A.; Hilburger, Mark W.

    2011-01-01

    In recent years, fiber-reinforced composites have become more accepted for aerospace applications. Specifically, during NASA s recent efforts to develop new launch vehicles, composite materials were considered and baselined for a number of structures. Because of mass and stiffness requirements, sandwich composites are often selected for many applications. However, there are a number of manufacturing and in-service concerns associated with traditional honeycomb-core sandwich composites that in certain instances may be alleviated through the use of other core materials or construction methods. Fluted-core, which consists of integral angled web members with structural radius fillers spaced between laminate face sheets, is one such construction alternative and is considered herein. Two different fluted-core designs were considered: a subscale design and a full-scale design sized for a heavy-lift-launch-vehicle interstage. In particular, axial compression of fluted-core composites was evaluated with experiments and finite-element analyses (FEA); axial compression is the primary loading condition in dry launch-vehicle barrel sections. Detailed finite-element models were developed to represent all components of the fluted-core construction, and geometrically nonlinear analyses were conducted to predict both buckling and material failures. Good agreement was obtained between test data and analyses, for both local buckling and ultimate material failure. Though the local buckling events are not catastrophic, the resulting deformations contribute to material failures. Consequently, an important observation is that the material failure loads and modes would not be captured by either linear analyses or nonlinear smeared-shell analyses. Compression-after-impact (CAI) performance of fluted core composites was also investigated by experimentally testing samples impacted with 6 ft.-lb. impact energies. It was found that such impacts reduced the ultimate load carrying capability by

  6. Spontaneous Neuronal Network Dynamics Reveal Circuit’s Functional Adaptations for Behavior

    PubMed Central

    Romano, Sebastián A.; Pietri, Thomas; Pérez-Schuster, Verónica; Jouary, Adrien; Haudrechy, Mathieu; Sumbre, Germán

    2015-01-01

    Summary Spontaneous neuronal activity is spatiotemporally structured, influencing brain computations. Nevertheless, the neuronal interactions underlying these spontaneous activity patterns, and their biological relevance, remain elusive. Here, we addressed these questions using two-photon calcium imaging of intact zebrafish larvae to monitor the neuron-to-neuron spontaneous activity fine structure in the tectum, a region involved in visual spatial detection. Spontaneous activity was organized in topographically compact assemblies, grouping functionally similar neurons rather than merely neighboring ones, reflecting the tectal retinotopic map despite being independent of retinal drive. Assemblies represent all-or-none-like sub-networks shaped by competitive dynamics, mechanisms advantageous for visual detection in noisy natural environments. Notably, assemblies were tuned to the same angular sizes and spatial positions as prey-detection performance in behavioral assays, and their spontaneous activation predicted directional tail movements. Therefore, structured spontaneous activity represents “preferred” network states, tuned to behaviorally relevant features, emerging from the circuit’s intrinsic non-linear dynamics, adapted for its functional role. PMID:25704948

  7. Sex-based differences in the adaptive value of social behavior contrasted against morphology and environment.

    PubMed

    Vander Wal, E; Festa-Bianchet, M; Réale, D; Coltman, D W; Pelletier, F

    2015-03-01

    The adaptive nature of sociality has long been a central question in ecology and evolution. However, the relative importance of social behavior for fitness, compared to morphology and environment, remains largely unknown. We assessed the importance of sociality for fitness (lamb production and survival) in a population of mark6d bighorn sheep (Ovis canadensis) over 16 years (n = 1022 sheep-years). We constructed social networks from observations (n = 38,350) of group membership (n = 3150 groups). We then tested whether consistent individual differences in social behavior (centrality) exist and evaluated their relative importance compared to factors known to affect fitness: mass, age, parental effects, and population density. Sheep exhibited consistent individual differences in social centrality. Controlling for maternal carryover effects and age, the positive effect of centrality in a social network on adult female lamb production and survival was equal or greater than the effect of body mass or population density. Social centrality had less effect on male survival and no effect on adult male lamb production or lamb survival. Through its effect on lamb production and survival, sociality in fission-fusion animal societies may ultimately influence population dynamics equally or more than morphological or environmental effects. PMID:26236860

  8. Optimization of Wear Behavior of Magnesium Alloy AZ91 Hybrid Composites Using Taguchi Experimental Design

    NASA Astrophysics Data System (ADS)

    Girish, B. M.; Satish, B. M.; Sarapure, Sadanand; Basawaraj

    2016-06-01

    In the present paper, the statistical investigation on wear behavior of magnesium alloy (AZ91) hybrid metal matrix composites using Taguchi technique has been reported. The composites were reinforced with SiC and graphite particles of average size 37 μm. The specimens were processed by stir casting route. Dry sliding wear of the hybrid composites were tested on a pin-on-disk tribometer under dry conditions at different normal loads (20, 40, and 60 N), sliding speeds (1.047, 1.57, and 2.09 m/s), and composition (1, 2, and 3 wt pct of each of SiC and graphite). The design of experiments approach using Taguchi technique was employed to statistically analyze the wear behavior of hybrid composites. Signal-to-noise ratio and analysis of variance were used to investigate the influence of the parameters on the wear rate.

  9. Micromechanical characterization of nonlinear behavior of advanced polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Chen, J. L.; Sun, C. T.

    1994-01-01

    Due to the presence of curing stresses and oriented crystalline structures in the matrix of polymer matrix fiber composites, the in situ nonlinear properties of the matrix are expected to be rather different from those of the bulk resin. A plane stress micromechanical model was developed to retrieve the in situ elastic-plastic properties of Narmco 5260 and Amoco 8320 matrices from measured elastic-plastic properties of IM7/5260 and IM7/8320 advance composites. In the micromechanical model, the fiber was assumed to be orthotropically elastic and the matrix to be orthotropic in elastic and plastic properties. The results indicate that both in situ elastic and plastic properties of the matrices are orthotropic.

  10. Thermal expansion behavior of LDEF metal matrix composites

    NASA Technical Reports Server (NTRS)

    Le, T. D.; Steckel, G. L.

    1992-01-01

    The effects of the space environment on the thermal expansion stability of metal matrix composites (graphite/Al and graphite/Mg) will be presented. A sample from each category of metal matrix composites mounted on the leading and trailing edge was chosen for analysis of the temperature-time-thermal strain histories. Typical thermal expansion curves over the same range of temperature were selected at the beginning, mid, and end of the recording duration. The thermal expansion of selected post-flight LDEF samples were measured over the same range of temperature in the laboratory using a Michelson laser interferometer. The thermal strains were monitored concurrently with a laser interferometer and a mounted strain gage.

  11. Analytical and numerical modeling of the mechanical behavior of metal matrix composites

    NASA Astrophysics Data System (ADS)

    Elfishawy, Karim Fouad

    Metal matrix composites (MMCs) subjected to both external and thermal cycling loading can experience enhanced creep deformation, leading to dimensional instability in some cases. Three-dimensional finite element models have been constructed to predict the behavior of composites under such loading conditions. The different possible types of composite behavior are discussed in detail. The language and ideas developed in the continuum mechanics area of ratcheting and shakedown was shown to correlate quite closely to the thermal cycling behavior of composites and to apply to their analysis and design. Three composite configurations were analyzed analytically and their models were used to construct Composite Behavior Maps (CBMs). CBMs are diagrams which delineate regions of dimensionally stable and unstable composite behavior, and were shown to have a characteristic shape. Experimental and analytical methods are outlined for constructing conservative CBMs for complex composite configurations for which analytical solutions are not possible. The utility of such diagrams as both an analysis and design tool for MMCs on the microstructural scale is discussed in detail. The fundamental elastic and plastic properties of a new non-traditional alumina/aluminum composite where both phases are continuous, known as Csp4, were investigated analytically using finite element simulations and compared to experimental results. The composite behaves in a nearly bilinear manner defined by an elastic modulus and an elastic-plastic modulus. The apparent plasticity in the composite was shown to occur by true plastic deformation of aluminum and elastic accommodation of alumina. Effects of residual stresses and matrix strength on the tensile and compressive behavior of the composite were also investigated. The concept of selective reinforcement is discussed, along with its special considerations and limitations. The applicability and effectiveness of selective reinforcement as a design approach

  12. Mechanical Behavior of Notched SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Gyekenyesi, John Z.; Gyekenyesi, Andrew L.; Levine, Stanley (Technical Monitor)

    2001-01-01

    Gas turbine components such as combustor liners or turbine vanes are subject to regions of high stress-concentration, e.g., attachment to the frame or at cooling holes. Ceramic matrix composites (CMCs) are potential materials for high temperature applications in gas turbines. They offer some capability to relieve stress at regions of high stress-concentration via matrix damage accumulation. In this study notch sensitivity was examined for woven SiC fiber reinforced, melt-infiltrated SiC matrix composites with a BN interphase, utilizing either Hi-Nicalo(TM) fibers or the stiffer Sylramic fibers. The double-edge notched tensile test approach was used for a wide range of notch sizes and specimen widths. Both composite systems exhibited mild notch sensitivity similar to other CMC systems. Acoustic emission, detected during the tensile tests, indicated that matrix cracking occurred around notches at net-section stresses below the stress where matrix cracking first occurs in unnotched specimens. However, thermoelastic stress analysis did not show any measurable stress relief around notches after the specimens were preloaded.

  13. Stability of executive function and predictions to adaptive behavior from middle childhood to pre-adolescence

    PubMed Central

    Harms, Madeline B.; Zayas, Vivian; Meltzoff, Andrew N.; Carlson, Stephanie M.

    2014-01-01

    The shift from childhood to adolescence is characterized by rapid remodeling of the brain and increased risk-taking behaviors. Current theories hypothesize that developmental enhancements in sensitivity to affective environmental cues in adolescence may undermine executive function (EF) and increase the likelihood of problematic behaviors. In the current study, we examined the extent to which EF in childhood predicts EF in early adolescence. We also tested whether individual differences in neural responses to affective cues (rewards/punishments) in childhood serve as a biological marker for EF, sensation-seeking, academic performance, and social skills in early adolescence. At age 8, 84 children completed a gambling task while event-related potentials (ERPs) were recorded. We examined the extent to which selections resulting in rewards or losses in this task elicited (i) the P300, a post-stimulus waveform reflecting the allocation of attentional resources toward a stimulus, and (ii) the SPN, a pre-stimulus anticipatory waveform reflecting a neural representation of a “hunch” about an outcome that originates in insula and ventromedial PFC. Children also completed a Dimensional Change Card-Sort (DCCS) and Flanker task to measure EF. At age 12, 78 children repeated the DCCS and Flanker and completed a battery of questionnaires. Flanker and DCCS accuracy at age 8 predicted Flanker and DCCS performance at age 12, respectively. Individual differences in the magnitude of P300 (to losses vs. rewards) and SPN (preceding outcomes with a high probability of punishment) at age 8 predicted self-reported sensation seeking (lower) and teacher-rated academic performance (higher) at age 12. We suggest there is stability in EF from age 8 to 12, and that childhood neural sensitivity to reward and punishment predicts individual differences in sensation seeking and adaptive behaviors in children entering adolescence. PMID:24795680

  14. Investigations into the mechanical behavior of composite bolted joints

    NASA Technical Reports Server (NTRS)

    Perry, J. C.; Hyer, M. W.

    1979-01-01

    Testing procedures and data reduction and interpretation techniques were established for a program to study the mechanical behavior of bolted joints at room temperature, -157 C (-250 F), and 315 C (600 F). The load transfer characteristics, from one bolt to another, in double-bolt joints were investigated by examining data generated in previous investigations. From the results, it appears the increase in load-carrying capacity by adding a second bolt in tandem can be predicted.

  15. Investigations into the mechanical behavior of composite bolted joints

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.; Perry, J. C.; Hyer, M. W.

    1979-01-01

    Testing procedures, data reduction, and data interpretation methods used to study the mechanical behavior of graphite-polyimide bolted joints at room temperature, -157 C (-250 F), and 315 C (600 F) are described. The load transfer characteristics, from one bolt to another, in double-bolt joints were determined by examining data generated in previous investigations. From the results, it appears the increase in load-carrying capacity by adding a second bolt in tandem can be predicted.

  16. The use of the spectral method within the fast adaptive composite grid method

    SciTech Connect

    McKay, S.M.

    1994-12-31

    The use of efficient algorithms for the solution of partial differential equations has been sought for many years. The fast adaptive composite grid (FAC) method combines an efficient algorithm with high accuracy to obtain low cost solutions to partial differential equations. The FAC method achieves fast solution by combining solutions on different grids with varying discretizations and using multigrid like techniques to find fast solution. Recently, the continuous FAC (CFAC) method has been developed which utilizes an analytic solution within a subdomain to iterate to a solution of the problem. This has been shown to achieve excellent results when the analytic solution can be found. The CFAC method will be extended to allow solvers which construct a function for the solution, e.g., spectral and finite element methods. In this discussion, the spectral methods will be used to provide a fast, accurate solution to the partial differential equation. As spectral methods are more accurate than finite difference methods, the ensuing accuracy from this hybrid method outside of the subdomain will be investigated.

  17. Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites

    NASA Technical Reports Server (NTRS)

    Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

    1995-01-01

    The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

  18. Second-order estimate of the macroscopic behavior of periodic hyperelastic composites: theory and experimental validation

    NASA Astrophysics Data System (ADS)

    Lahellec, N.; Mazerolle, F.; Michel, J. C.

    2004-01-01

    This paper deals with some theoretical and experimental aspects of the behavior of periodic hyperelastic composites. We focus here on composites consisting of an elastomeric matrix periodically reinforced by long fibers. The paper is composed of three parts. The first part deals with the theoretical aspects of compressible behavior. The second-order theory of Ponte Castañeda (J. Mech. Phys. Solids 44 (1996) 827) is considered and extended to periodic microstructures. Comparisons with results obtained by the finite element method show that the composite behavior predicted by the present model is much more accurate for compressible than for incompressible materials. The second part deals with the extension of the method to incompressible behavior. A mixed formulation (displacement-pressure) is used which improves the accuracy of the estimate given by the model. The third part presents experimental results. The composite tested is made of a rubber matrix reinforced by steel wires. Firstly, the matrix behavior is identified with a tensile test and a shear test carried out on homogeneous samples. Secondly, the composite is tested under shearing. The experimentally measured homogenized stress is then compared with the predictions of the model.

  19. Thermo-mechanical Response and Damping Behavior of Shape Memory Alloy-MAX Phase Composites

    NASA Astrophysics Data System (ADS)

    Kothalkar, Ankush Dilip; Benitez, Rogelio; Hu, Liangfa; Radovic, Miladin; Karaman, Ibrahim

    2014-05-01

    NiTi/Ti3SiC2 interpenetrating composites that combine two unique material systems—a shape memory alloy (SMA) and a MAX phase—demonstrating two different pseudoelastic mechanisms, were processed using spark plasma sintering. The goal of mixing these two material systems was to enhance the damping behavior and thermo-mechanical response of the composite by combining two pseudoelastic mechanisms, i.e., reversible stress-induced martensitic transformation in SMA and reversible incipient kink band formation in MAX phase. Equal volume fractions of equiatomic NiTi and Ti3SiC2 were used. Microstructural characterization was conducted using scanning electron microscopy to study the distribution of NiTi, Ti3SiC2, and remnant porosity in the composite. Thermo-mechanical testing in the form of thermal cycles under constant stress levels was performed in order to characterize shape memory behavior and thereby introducing residual stresses in the composites. Evolution of two-way shape memory effect was studied and related to the presence of residual stresses in the composites. Damping behavior, implying the energy dissipation per loading-unloading cycle under increasing compressive stresses, of pure NiTi, pure Ti3SiC2, as-sintered, and thermo-mechanically cycled (TC) NiTi/Ti3SiC2 composites, was investigated and compared to the literature data. In this study, the highest energy dissipation was observed for the TC composite followed by the as-sintered (AS) composite, pure NiTi, and pure Ti3SiC2 when compared at the same applied stress levels. Both the AS and TC composites showed higher damping up to 200 MPa stress than any of the metal—MAX phase composites reported in the literature to date. The ability to enhance the performance of the composite by controlling the thermo-mechanical loading paths was further discussed.

  20. Vibroacoustic behavior and noise control studies of advanced composite structures

    NASA Astrophysics Data System (ADS)

    Li, Deyu

    The research presented in this thesis is devoted to the problems of sound transmission and noise transmission control for advanced composite payload fairings. There are two advanced composite fairings under study. The first is a tapered, cylindrical advanced grid-stiffened composite fairing, and the second is a cylindrical ChamberCore composite fairing. A fully coupled mathematical model for characterizing noise transmission into a finite elastic cylindrical structure with application to the ChamberCore fairing is developed. It combines advantages of wave radiation principles and structural-acoustic modal interaction, and provides an ideal noise transmission model that can be extended to other finite cylindrical structures. Structural-acoustic dynamic parameters of the two fairings are obtained using a combination of numerical, analytical, and experimental approaches. An in-situ method for experimentally characterizing sound transmission into the fairings called noise reduction spectrum (NRS) is developed based on noise reduction. The regions of interest in the NRS curves are identified and verified during a passive control investigation, where various fill materials are added into wall-chambers of the ChamberCore fairing. Both Helmholtz resonators (HRs) and long T-shaped acoustic resonators (ARs) are also used to successfully control noise transmission into the ChamberCore fairing. In the process, an accurate model for the resonant frequency calculation and design of cylindrical HRs is derived. Further, a novel and more general model for the design of multi-modal, long, T-shaped ARs is developed, including three new end-correction equations that are validated experimentally. The control results show that noise attenuation is significant in the controlled modes, and the control is also observed in some modes that are not targeted, due to acoustic modal coupling via the structure. Helmholtz resonators are found to produce between 2.0 and 7.7 dB increase in NRS in

  1. Utilizing Matrix-Filler Interactions in the Design of Stimuli-Responsive, Mechanically-Adaptive Electrospun Composites

    NASA Astrophysics Data System (ADS)

    Wanasekara, Nandula; Stone, David; Wnek, Gary; Korley, Lashanda

    2013-03-01

    A new class of all-organic, stimuli-responsive and mechanically-adaptive electrospun nanocomposites, which have the ability to alter their stiffness upon hydration, were developed. These materials were fabricated by incorporating an electrospun mat of poly(vinyl alcohol) (PVA) as the filler in a polymeric matrix consisting of either poly(vinyl acetate) (PVAc) or ethylene oxide-epicholorohydrin copolymer (EO-EPI). The incorporation of high stiffness, high aspect ratio PVA filler mat significantly enhanced the tensile storage modulus of EO-EPI based composites, while modulus enhancement was only noticed above the glass transition for PVAc-based composites. Composite materials based on a rubbery EO-EPI host polymer and PVA filler exhibit an irreversible reduction by a factor of 12 of the tensile modulus upon hydration. In contrast, composites comprised of PVAc show a reversible reduction of modulus by a factor of 280 upon water uptake. The mechanical morphing of the electrospun composites is the result of the filler crystallinity, and matrix-filler interactions facilitated by the surface hydroxyl groups of the PVA filler. The choice of polymer matrix and electrospun nanofiber fillers allow control of matrix-filler interactions in a new series of all-organic composites to achieve desired stimuli-responsiveness and mechanical-adaptability upon exposure to various stimuli.

  2. Effect of Structure on the Mechanical Behaviors of Three-Dimensional Spacer Fabric Composites

    NASA Astrophysics Data System (ADS)

    Li, Min; Wang, Shaokai; Zhang, Zuoguang; Wu, Boming

    2009-02-01

    Three-dimensional (3-D) spacer fabric composite is a newly developed sandwich structure, the reinforcement of which is integrally woven by advanced textile technique. Two facesheets of 3-D spacer fabric are connected by continuous fibers, named pile in the core, providing excellent properties like outstanding integrity, debonding resistance, light weight, good designability and so on. Usually the 3-D spacer fabric composite without extra reinforcement is a kind of core material. In comparison with the facesheet reinforced spacer fabric composite, here the composite without additional weaves is called mono-spacer fabric composite. In this paper, two kinds of mono-spacer fabric composites with integrated hollow cores have been developed, one with 8-shaped piles and the other with corrugated piles. The mechanical characteristics and the damage modes of these mono-spacer fabric composites under different load conditions have been investigated. Besides, effects of pile height, pile distribution density and pile structure on the composites mechanical performances were analyzed. It is shown that the mechanical performances of mono-spacer fabric composites can be widely adapted to the respective requirements through the choice of the structural factors.

  3. Adaptive evolution of a derived radius morphology in manakins (Aves, Pipridae) to support acrobatic display behavior.

    PubMed

    Friscia, Anthony; Sanin, Gloria D; Lindsay, Willow R; Day, Lainy B; Schlinger, Barney A; Tan, Josh; Fuxjager, Matthew J

    2016-06-01

    The morphology of the avian skeleton is often studied in the context of adaptations for powered flight. The effects of other evolutionary forces, such as sexual selection, on avian skeletal design are unclear, even though birds produce diverse behaviors that undoubtedly require a variety of osteological modifications. Here, we investigate this issue in a family of passerine birds called manakins (Pipridae), which have evolved physically unusual and elaborate courtship displays. We report that, in species within the genus Manacus, the shaft of the radius is heavily flattened and shows substantial solidification. Past work anecdotally notes this morphology and attributes it to the species' ability to hit their wings together above their heads to produce loud mechanical sonations. Our results show that this feature is unique to Manacus compared to the other species in our study, including a variety of taxa that produce other sonations through alternate wing mechanisms. At the same time, our data reveal striking similarities across species in total radius volume and solidification. Together, this suggests that supposedly adaptive alterations in radial morphology occur within a conserved framework of a set radius volume and solidness, which in turn is likely determined by natural selection. Further allometric analyses imply that the radius is less constrained by body size and the structural demands that underlie powered flight, compared to other forelimb bones that are mostly unmodified across taxa. These results are consistent with the idea that the radius is more susceptible to selective modification by sexual selection. Overall, this study provides some of the first insight into the osteological evolution of passerine birds, as well as the way in which opposing selective forces can shape skeletal design in these species. J. Morphol. 277:766-775, 2016. © 2016 Wiley Periodicals, Inc. PMID:27027525

  4. Fatigue behavior of continuous fiber silicon-carbide-aluminum composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Wallis, R. R.

    1984-01-01

    Four lay-ups of continuous fiber silicon carbide (SCS2) fiber/aluminum matrix composites were tested to assess fatigue mechanisms including stiffness loss when cycled below their respective fatigue limits. The lay-ups were 0 (sub 8), 0(sub 2)/ + or - 45 (sub 2s), 0/90 (sub 2s),and 0/ + or 45/90 (subs). The data were compared with predictions from the author's previously published shakedown model which predicts fatigue-induced stiffness loss in metal matrix composites. A fifth lay-up, + or - 45 (sub 2s), was tested to compare shakedown and fatigue limits. The particular batch of silicon-carbide fibers tested in this program had a somewhat lower modulus (340 GPa) than expected and displayed poor bonding to the aluminum matrix. Good agreement was obtained between the stiffness loss model and the test data. The fatigue damage below the fatigue limit was primarily in the form of matrix cracking. The fatigue limit corresponded to the laminate shakedown for the + or - 45 (sub 2s) laminate.

  5. Mechanical Behavior of Electrospun Palmfruit Bunch Reinforced Polylactide Composite Fibers

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Peter, A. A.; Olaleye, Samuel Adebayo

    2016-01-01

    In this study, the mechanical characteristics of electrospun palm fruit bunch reinforced poly lactic acid (PLA) nanofiber composites using treated and untreated filler was examined. Poly lactic acid-palm fruit bunch-dichloromethane blends were electrospun by varying the concentration of the palm fruit bunch between 0 wt.% and 8 wt.%. A constant voltage of 26 kV was applied, the tip-to-collector distance was maintained at 27.5 cm and PLA-palm fruit bunch-dichloromethane (DCM) concentration of 12.5% (w/v) was used. The results revealed that the presence of untreated palm fruit bunch fillers in the electrospun PLA matrix significantly reduces the average diameters of the fibers, causing the formation of beads. As a result there are reductions in tensile strengths of the fibers. The presence of treated palm fruit bunch fillers in the electrospun PLA matrix increases the average diameters of the fibers with improvements in the mechanical properties. The optimal mechanical responses were obtained at 3 wt.% of the treated palm fruit bunch fillers in the PLA matrix. However, increase in the palm fruit fillers (treated and untreated) in the PLA matrix promoted the formation of beads in the nanofiber composites.

  6. The experimental behavior of spinning pretwisted laminated composite plates

    NASA Technical Reports Server (NTRS)

    Kosmatka, John B.; Lapid, Alex J.

    1993-01-01

    The purpose of the research is to gain an understanding of the material and geometric couplings present in advanced composite turbo-propellers. Twelve pre-twisted laminated composite plates are tested. Three different ply lay-ups (2 symmetric and 1 asymmetric) and four different geometries (flat and 30x pre-twist about the mid-chord, quarter-chord, and leading edge) distinguish each plate from one another. Four rotating and non-rotating tests are employed to isolate the material and geometric couplings of an advanced turbo propeller. The first series of tests consist of non-rotating static displacement, strain, and vibrations. These tests examine the effects of ply lay-up and geometry. The second series of tests consist of rotating displacement, strain, and vibrations with various pitch and sweep settings. These tests utilize the Dynamic Spin Rig Facility at the NASA Lewis Research Center. The rig allows the spin testing of the plates in a near vacuum environment. The tests examine how the material and plate geometry interact with the pitch and sweep geometry of an advanced turbo-propeller.

  7. Two Boys with Multiple Disabilities Increasing Adaptive Responding and Curbing Dystonic/Spastic Behavior via a Microswitch-Based Program

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Didden, Robert; Oliva, Doretta

    2009-01-01

    A recent study has shown that microswitch clusters (i.e., combinations of microswitches) and contingent stimulation could be used to increase adaptive responding and reduce dystonic/spastic behavior in two children with multiple disabilities [Lancioni, G. E., Singh, N. N., Oliva, D., Scalini, L., & Groeneweg, J. (2003). Microswitch clusters to…

  8. Does a Measure of Support Needs Predict Funding Need Better Than a Measure of Adaptive and Maladaptive Behavior?

    PubMed

    Arnold, Samuel R C; Riches, Vivienne C; Stancliffe, Roger J

    2015-09-01

    Internationally, various approaches are used for the allocation of individualized funding. When using a databased approach, a key question is the predictive validity of adaptive behavior versus support needs assessment. This article reports on a subset of data from a larger project that allowed for a comparison of support needs and adaptive behavior assessments when predicting person-centered funding allocation. The first phase of the project involved a trial of the Inventory for Client and Agency Planning (ICAP) adaptive behavior and Instrument for the Classification and Assessment of Support Needs (I-CAN)-Brief Research version support needs assessments. Participants were in receipt of an individual support package allocated using a person-centered planning process, and were stable in their support arrangements. Regression analysis showed that the most useful items in predicting funding allocation came from the I-CAN-Brief Research. No additional variance could be explained by adding the ICAP, or using the ICAP alone. A further unique approach of including only items from the I-CAN-Brief Research marked as funded supports showed high predictive validity. It appears support need is more effective at determining resource need than adaptive behavior. PMID:26322387

  9. An Adaptive Approach to Family Intervention: Linking Engagement in Family-Centered Intervention to Reductions in Adolescent Problem Behavior

    ERIC Educational Resources Information Center

    Connell, Arin M.; Dishion, Thomas J.; Yasui, Miwa; Kavanagh, Kathryn

    2007-01-01

    This study used Complier Average Causal Effect analysis (CACE; see G. Imbens & D. Rubin, 1997) to examine the impact of an adaptive approach to family intervention in the public schools on rates of substance use and antisocial behavior among students ages 11-17. Students were randomly assigned to a family-centered intervention (N = 998) in 6th…

  10. An Overview of Intervention Options for Promoting Adaptive Behavior of Persons with Acquired Brain Injury and Minimally Conscious State

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Bosco, Andrea; Belardinelli, Marta Olivetti; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff

    2010-01-01

    This paper presents an overview of the studies directed at helping post-coma persons with minimally conscious state improve their adaptive behavior. Twenty-one studies were identified for the 2000-2010 period (i.e., a period in which an intense debate has occurred about diagnostic, rehabilitative, prognostic, and ethical issues concerning people…

  11. Longitudinal study of cognitive abilities and adaptive behavior levels in fragile X males: a prospective multicenter analysis.

    PubMed

    Fisch, G S; Simensen, R; Tarleton, J; Chalifoux, M; Holden, J J; Carpenter, N; Howard-Peebles, P N; Maddalena, A

    1996-08-01

    Retrospective longitudinal studies have noted declines in IQ scores in many but not all fra(X) (fragile X) males and females. We report on a prospective investigation of longitudinal changes in cognitive ability (IQ) and adaptive behavior (DQ) in 24 fra(X) males from four test sites. Individuals who were tested ranged in age from 3-15 years. To determine cognitive ability, all males were administered the Stanford-Binet test (4th Edition). To assess adaptive behavior, all males were evaluated using the Vineland Adaptive Behavior Scales. Mean interest interval was 2.3 years. Using identical DNA protocols, all subjects were identified as bearing the fra(X) mutation. Results showed declines in IQ scores in 18/24 (75%) males. Four males showed no change in scores. Declines in DQ scores were noted in 22/24 (92%) of those tested. DQ scores were higher than IQ scores in 20/24 (83%) subjects. From a descriptive cohort analysis, decreases in IQ scores appear to follow a well-defined, negatively decelerating function. Declines in DQ were steeper and more nearly linear. Declining scores are not indicative of regression of intellectual and/or social skills, but of a relative inability to keep pace with their age-normed cohort. We conclude that the fra(X) mutation affects cognitive abilities in a uniform, nonlinear manner comparable to outcomes observed in earlier retrospective studies. Adaptive behavior also declines, but in a more linear fashion. PMID:8844080

  12. An Annotated Bibliography of the Literature Concerning Students' Adaptive and Maladaptive Behavior Patterns in Response to Failure in Achievement Situations.

    ERIC Educational Resources Information Center

    Moriarty, Kathleen Pelletier

    An examination of the dynamics of academic failure is presented in this monograph in the form of an annotated bibliography of current literature. The writings cited offer a cross-section of research on what factors affect students' choices of adaptive or maladaptive behavior patterns in the classroom and in relation to their peers. Section one of…

  13. Adapting Phonological Awareness Interventions for Children with Down Syndrome Based on the Behavioral Phenotype: A Promising Approach?

    ERIC Educational Resources Information Center

    Lemons, Christopher J.; King, Seth A.; Davidson, Kimberly A.; Puranik, Cynthia S.; Fulmer, Deborah; Mrachko, Alicia A.; Partanen, Jane; Al Otaiba, Stephanie; Fidler, Deborah J.

    2015-01-01

    Many children with Down syndrome demonstrate deficits in phonological awareness, a prerequisite to learning to read in an alphabetic language. The purpose of this study was to determine whether adapting a commercially available phonological awareness program to better align with characteristics associated with the behavioral phenotype of Down…

  14. Emotional Intelligence and Adaptive Success of Nurses Caring for People with Mental Retardation and Severe Behavior Problems

    ERIC Educational Resources Information Center

    Gerits, Linda; Derksen, Jan J. L.; Verbruggen, Antoine B.

    2004-01-01

    The emotional intelligence profiles, gender differences, and adaptive success of 380 Dutch nurses caring for people with mental retardation and accompanying severe behavior problems are reported. Data were collected with the Bar-On Emotional Quotient Inventory, Utrecht-Coping List, Utrecht-Burnout Scale, MMPI-2, and GAMA. Absence due to illness…

  15. The Relationship between Parent Report of Adaptive Behavior and Direct Assessment of Reading Ability in Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Arciuli. Joanne; Stevens, Kirsten; Trembath, David; Simpson, Ian Craig

    2013-01-01

    Purpose: This study was designed to shed light on the profile of reading ability in children with autism spectrum disorder (ASD). A key aim was to examine the relationship between parent report of adaptive behavior and direct assessment of reading ability in these children. Method: The authors investigated children's reading ability using the…

  16. Adaptation of Social Problem Solving for Children Questionnaire in 6 Age Groups and its Relationships with Preschool Behavior Problems

    ERIC Educational Resources Information Center

    Dereli-Iman, Esra

    2013-01-01

    Social Problem Solving for Child Scale is frequently used to determine behavioral problems of children with their own word and to identify ways of conflict encountered in daily life, and interpersonal relationships in abroad. The primary purpose of this study was to adapt the Wally Child Social Problem-Solving Detective Game Test. In order to…

  17. The Contribution of Children's Self-Regulation and Classroom Quality to Children's Adaptive Behaviors in the Kindergarten Classroom

    ERIC Educational Resources Information Center

    Rimm-Kaufman, Sara E.; Curby, Tim W.; Grimm, Kevin J.; Brock, Laura L.; Nathanson, Lori

    2009-01-01

    In this study, the authors examined the extent to which children's self-regulation upon kindergarten entrance and classroom quality in kindergarten contributed to children's adaptive classroom behavior. Children's self-regulation was assessed using a direct assessment upon entrance into kindergarten. Classroom quality was measured on the basis of…

  18. Promoting Adaptive Behavior in Persons with Acquired Brain Injury, Extensive Motor and Communication Disabilities, and Consciousness Disorders

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Belardinelli, Marta Olivetti; Buonocunto, Francesca; Sacco, Valentina; Navarro, Jorge; Lanzilotti, Crocifissa; De Tommaso, Marina; Megna, Marisa; Badagliacca, Francesco

    2012-01-01

    These two studies extended the evidence on the use of technology-based intervention packages to promote adaptive behavior in persons with acquired brain injury and multiple disabilities. Study I involved five participants in a minimally conscious state who were provided with intervention packages based on specific arrangements of optic, tilt, or…

  19. Family Emotional Climate and Sibling Relationship Quality: Influences on Behavioral Problems and Adaptation in Preschool-Aged Children

    ERIC Educational Resources Information Center

    Modry-Mandell, Kerri L.; Gamble, Wendy C.; Taylor, Angela R.

    2007-01-01

    We examined the impact of family emotional climate and sibling relationship quality on behavioral problems and adaptation in preschool-aged children. Participants were 63 mothers with a preschool-aged child enrolled in a Southern Arizona Head Start Program. Siblings were identified as children closest in age to target child. Mothers of…

  20. Two Children with Multiple Disabilities Increase Adaptive Object Manipulation and Reduce Inappropriate Behavior via a Technology-Assisted Program

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; O'Reilly, Mark F.; Singh, Nirbhay N.; Sigafoos, Jeff; Didden, Robert; Oliva, Doretta; Campodonico, Francesca

    2010-01-01

    Persons with severe to profound multiple disabilities, such as intellectual, visual, and motor disabilities, may be characterized by low levels of adaptive engagement with the environment. They may also display forms of inappropriate, stereotypical behavior (like hand mouthing, that is, putting their fingers into or over their mouths) or…

  1. Effect of cyclic loading on marginal adaptation and bond strength in direct vs. indirect class II MO composite restorations.

    PubMed

    Aggarwal, Vivek; Logani, Ajay; Jain, Veena; Shah, Naseem

    2008-01-01

    This study evaluated the effect of cyclic loading on the marginal adaptation and microtensile bond strength of direct vs indirect Class II composite restorations in an in-vitro model. Forty Class II cavities were prepared on the mesial surface of extracted human maxillary first premolars and divided into two groups: Group I--direct composite restorations and Group II--indirect composite restorations. Groups I and II were further divided into subgroups: A (without cyclic loading) and B (with cyclic loading of 150,000 cycles at 60N). The gingival margin of the proximal box was evaluated at 200x magnification for marginal adaptation in a low vacuum scanning electron microscope. The restorations were sectioned perpendicular to the bonded surface into 1 mm thickslabs. The slabswere further trimmed at the interface to produce a cross-sectional surface area of approximately 1 mm2. All specimens were subjected to microtensile bond strength testing. The marginal adaptation was analyzed using descriptive studies and bond strength data were analyzed by one-way ANOVA test. The indirect composite restorations performed better under cyclic loading. PMID:18833866

  2. Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

    Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

  3. Tethered Nanoparticle -Polymer Composites: Phase behavior and rheology

    NASA Astrophysics Data System (ADS)

    Mangal, Rahul; Archer, Lynden A.

    2014-03-01

    Polymer nanocomposites with particle radius (a) approaching the radius of gyration (Rg) of entangled host polymer have been reported to exhibit an unusual negative reinforcement effect, which leads to an anomalous reduction in relative an anomalous reduction in relative viscosity at low particle loadings (φ) . This so-called Non-Einsteinian flow behavior is understood to be sensitive to the dispersion state of particles in host polymer. We studied suspensions of SiO2 nanoparticles tethered with polethylene glycol (PEG) in polymethylmethacralate (PMMA) with molecular weights (Mw) from 17 KDa to 280 KDa. Due to strong enthalpic interactions between PEG and PMMA (χ = -0.65), nanoparticles are expected to be well-dispersed, independent of Mw of PMMA. Using small angle x-ray scattering measurements we show that the phase stability of suspensions depends on Mw of the tethered PEG, host PMMA, and φ. Particles functionalized with low molecular weight PEG aggregate at low φ, but disperse at high φ. In contrast, nanoparticles functionalized with higher molecular weight PEG are well dispersed for host chain lengths (P) to tethered chain length (N), (P/N), is as high as 160. The stability boundary of these suspensions extends well beyond expectations for nanocomposites based on tethered PEG chains suspended in PEG. Through in-depth analysis of rheology and x-ray photon correlation spectra we explore the fundamental origins of non-Einsteinian flow behavior. King Abdullah University of Science and Technology (KAUST), Advanced Photon Source (APS).

  4. Hydrocarbons in soils: Origin, composition, and behavior (Review)

    NASA Astrophysics Data System (ADS)

    Gennadiev, A. N.; Pikovskii, Yu. I.; Tsibart, A. S.; Smirnova, M. A.

    2015-10-01

    It has been shown that a large body of evidence on the sources, transformation, and migration of hydrocarbons in soils has been acquired by different researchers. Available data about the origin and behavior of hydrocarbon gases, total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, alkanes, and other compounds have been considered successively. A wide range of natural and anthropogenic factors affecting the transformation and migration of hydrocarbons in soils have been analyzed. The indicative value of these compounds has been explained. At the same time, many problems related to hydrocarbons in soils are still insufficiently understood. Sparse and fragmentary data are available in the literature on the interaction of different hydrocarbon groups in the soil. Few data refer to the features of hydrocarbons in background zonal soils; there are almost no interzonal comparisons. The behavior of hydrocarbons in soils of different landscape-geographical positions is characterized in isolated publications. The hydrocarbon status of soils as an integral complex of interrelated hydrocarbons is almost not analyzed. Hydrocarbons of a single class (polycyclic aromatic hydrocarbons, hydrocarbon gases, n-alkanes, etc.) are usually characterized in each publication.

  5. Dynamic Composition and Execution of Behaviors in a Hierarchical Control System

    NASA Astrophysics Data System (ADS)

    Skillman, Thomas L.; Hopping, Ken

    1990-03-01

    The behavior of a system can be defined as its trajectory in state space. A system's behavior comes about through the interaction of its control law with the plant dynamics. In systems where the plant dynamics vary considerably a constant control law can lead to varying behaviors. A more consistent operation of a system can be attained by specifying the desired behavior and then, based on the current plant dynamics, selecting the appropriate control law. Assuming that only the lowest level of a hierarchical controller is responsible for selecting the appropriate control law, the rest of the hierarchy needs only to represent and operate on abstracted state spaces and behaviors. Here a hierarchical control system is presented that operates as a hierarchy of behaviors, rather than control laws, to achieve adaptive real-time control performance. A planning system at each level of the hierarchy composes sequences of behaviors that will implement a more abstract behavior specified by the next higher level. The first intermediate goal state generated by a plan is passed to the next lower level of the hierarchy as the goal state, and the planning sequence repeated. A set of relations is used to translate between the state abstractions at different levels. At the bottom level the behavior is mapped into a control law that will achieve the behavior when applied to the current plant dynamics. The system has been prototyped and demonstrated on a wheeled mobile robot platform with sonar range sensing.

  6. The viscoelastic behavior of a composite in a thermal environment

    NASA Technical Reports Server (NTRS)

    Morris, D. H.; Brinson, H. F.; Griffith, W. I.; Yeow, Y. T.

    1979-01-01

    A proposed method for the accelerated predictions of modulus and life times for time dependent polymer matrix composite laminates is presented. The method, based on the time temperature superposition principle and lamination theory, is described in detail. Unidirectional reciprocal of compliance master curves and the shift functions needed are presented and discussed. Master curves for arbitrarily oriented unidirectional laminates are predicted and compared with experimantal results obtained from master curves generated from 15 minute tests and with 25 hour tests. Good agreement is shown. Predicted 30 deg and 60 deg unidirectional strength master curves are presented and compared to results of creep rupture tests. Reasonable agreement is demonstrated. In addition, creep rupture results for a (90 deg + or - 60 deg/90 deg) sub 2s laminate are presented.

  7. Strengthening behavior of chopped multi-walled carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Shin, S.E.; Bae, D.H.

    2013-09-15

    Strengthening behavior of the aluminum composites reinforced with chopped multi-walled carbon nanotubes (MWCNTs) or aluminum carbide formed during annealing at 500 °C has been investigated. The composites were fabricated by hot-rolling the powders which were ball-milled under various conditions. During the early annealing process, aluminum atoms can cluster inside the tube due to the diffusional flow of aluminum atoms into the tube, providing an increase of the strength of the composite. Further annealing induces the formation of the aluminum carbide phase, leading to an overall drop in the strength of the composites. While the strength of the composites can be evaluated according to the rule of mixture, a particle spacing effect can be additionally imparted on the strength of the composites reinforced with the chopped MWCNTs or the corresponding carbides since the reinforcing agents are smaller than the submicron matrix grains. - Highlights: • Strengthening behavior of chopped CNT reinforced Al-based composites is investigated. • Chopped CNTs have influenced the strength and microstructures of the composites. • Chopped CNTs are created under Ar- 3% H2 atmosphere during mechanical milling. • Strength can be evaluated by the rule of the mixture and a particle spacing effect.

  8. Low-shrinkage dental restorative composite: modeling viscoelastic behavior during setting.

    PubMed

    Dauvillier, Bibi S; Feilzer, Albert J

    2005-04-01

    Much attention has been directed toward developing dental direct restorative composites that generate less shrinkage stress during setting. The aim of this study was to explore the viscoelastic behavior of a new class of low-shrinkage dental restorative composite during setting. The setting behavior of an experimental oxirane composite has been investigated by analyzing stress-strain data with two-parametric mechanical models. Experimental data were obtained from a dynamic test method, in which the setting light-activated composite was continuously subjected to sinusoidal strain cycles. The material parameters and the model's predictive capacity were analyzed with validated modeling procedures. The light-activated oxirane composite exhibited shrinkage delay and low polymerization shrinkage strain and stresses when compared with conventional light-activated composite. Noise in the stress data restricted the predictive ability of the Maxwell model to the elastic modulus development of the composite only. Evaluation tests of their potential as restorative material are required, to examine if the biocompatibility and mechanical properties after setting of oxirane composites are acceptable for dental use. PMID:15685614

  9. Computational Simulation of Continuous Fiber-Reinforced Ceramic Matrix Composites Behavior

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Chamis, Christos C.; Mital, Subodh K.

    1996-01-01

    This report describes a methodology which predicts the behavior of ceramic matrix composites and has been incorporated in the computational tool CEMCAN (CEramic Matrix Composite ANalyzer). The approach combines micromechanics with a unique fiber substructuring concept. In this new concept, the conventional unit cell (the smallest representative volume element of the composite) of the micromechanics approach is modified by substructuring it into several slices and developing the micromechanics-based equations at the slice level. The methodology also takes into account nonlinear ceramic matrix composite (CMC) behavior due to temperature and the fracture initiation and progression. Important features of the approach and its effectiveness are described by using selected examples. Comparisons of predictions and limited experimental data are also provided.

  10. Monotonic and cyclic deformation behavior of a SiCw/6061 Al composite at elevated temperature

    SciTech Connect

    Wang, L.; Sun, Z.M.; Kobayashi, T.

    1996-10-15

    With the advent of new processing techniques, the technological interest and research activity in the development of metal-matrix composites have increased rapidly. Particularly, discontinuously reinforced composites, such as whisker and particle reinforced aluminum-based metal-matrix composites, exhibit attractive advantages, such as high specific modulus, high specific strength, good fatigue resistance and easy fabrication. They have emerged as a new class of structural materials for ambient and elevated temperature applications in aerospace and automobile industries. Therefore, great attention has been paid on their mechanical properties. However, a limited number of investigations on the cyclic deformation behavior have been reported, and little research has been done in this aspect at elevated temperature. The present study is based on a previous study at room temperature to investigate the monotonic and cyclic deformation behavior of a SiC whisker reinforced 6061 Al alloy composite and its unreinforced counterpart at elevated temperature.

  11. Crystallization and recrystallization behavior study on biopolymer composites with polymer grafted halloysite nanotubes

    NASA Astrophysics Data System (ADS)

    Hsieh, Ya-Ting; Kojio, Ken; Takahara, Atsushi

    We study the crystallization and recrystallization behavior of poly(lactic acid) (PLA) in PLA/halloysite composites. Specifically, we are interested in finding the additional effect of interface properties variation in composites except for enhancing filler dispersion. Halloysite nanotubes are grafted with polymer to create different surface properties at their surface. These polymer grafted halloysite nanotubes are then spread into PLA via solvent mixing. Using differential scanning calorimeter, we track and analyze the influence of halloysite surface properties on the crystallization and recrystallization behavior of PLA composites under several conditions. We also present investigations of polarizing optical microscopy, in-situ Fourier transform infrared spectroscopy, and in-situ synchrotron X-ray diffraction measurements. The investigations provide insight into interface effect on PLA composites. The synchrotron WAXD measurements were performed on BL02B2 beamline at Spring-8 with the approval of the Japan Synchrotron Radiation Institute (JASRI) (Proposal No. 2015B1541).

  12. Some psychophysiological and behavioral aspects of adaptation to simulated autonomous Mission to Mars

    NASA Astrophysics Data System (ADS)

    Gushin, V.; Shved, D.; Vinokhodova, A.; Vasylieva, G.; Nitchiporuk, I.; Ehmann, B.; Balazs, L.

    2012-01-01

    “Mars-105” experiment was executed in March-July 2009 in Moscow, at the Institute for Bio-Medical Problems (IBMP) with participation of European Space Agency (ESA) to simulate some specific conditions of future piloted Mars mission. In the last 35 days of isolation, in order to simulate autonomous flight conditions, some serious restrictions were established for the crew resupply and communication with Mission Control (MC). The objective of the study was to investigate psychophysiological and behavioral aspects (communication) of adaptation during this period of “high autonomy”. We used computerized analysis of the crew written daily reports to calculate the frequencies of utilization of certain semantic units, expressing different psychological functions. To estimate the level of psycho-physiological stress, we measured the concentration of urinal cortisol once in two weeks. To investigate psycho-emotional state, we used the questionnaire SAN, estimating Mood, Activity and Health once in two weeks.During the simulation of autonomous flight, we found out the different tendencies of communicative behavior. One group of subjects demonstrated the tendency to “activation and self-government” under “high autonomy” conditions. The other subjects continued to use communicative strategy that we called “closing the communication channel”. “Active” communication strategy was accompanied by increasing in subjective scores of mood and activity. The subjects, whose communication strategy was attributed as “closing”, demonstrated the considerably lower subjective scores of mood and activity. Period of high autonomy causes specific changes in communication strategies of the isolated crew.

  13. Compression fatigue behavior of composites in the presence of delaminations

    NASA Technical Reports Server (NTRS)

    Ramkumar, R. L.

    1982-01-01

    Three different stacking sequences of a 64-ply layup were tested in an experimental investigation of the effect of idealized imbedded delaminations on the compression fatigue behavior of quasi-isotropic T300/5208 graphite-epoxy laminates. Postfailure examination of specimen cross sections revealed the absence of any fiber microbuckling, suggesting that the predominant failure mode was the propagation of imbedded delaminations in the tab region. One- and two-dimensional delaminations, respectively located across the entire width below the surface ply and buried one or four plies below the surface, were considered. A novel procedure employing minute, laser-drilled holes was successfully used in extending the application of diidobutane-enhaced radiography to buried delaminations.

  14. Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

    SciTech Connect

    Launey, Maximilien E.; Hofmann, Douglas C.; Suh, Jin-Yo; Kozachkov, Henry; Johnson, William L.; Ritchie, Robert O.

    2009-05-26

    Nonlinear-elastic fracture mechanics methods are used to assess the fracture toughness of bulk metallic glass (BMG) composites; results are compared with similar measurements for other monolithic and composite BMG alloys. Mechanistically, plastic shielding gives rise to characteristic resistance?curve behavior where the fracture resistance increases with crack extension. Specifically, confinement of damage by second?phase dendrites is shown to result in enhancement of the toughness by nearly an order of magnitude relative to unreinforced glass.

  15. Mechanical behavior and fracture characteristics of off-axis fiber composites. 2: Theory and comparisons

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1978-01-01

    The mechanical behavior and stresses inducing fracture modes of unidirectional high-modulus graphite-fiber/epoxy composites subjected to off-axis tensile loads were investigated theoretically. The investigation included the use of composite mechanics, combined-stress failure criteria, and finite-element stress analysis. The results are compared with experimental data and led to the formulation of criteria and convenient plotting procedures for identifying, characterizing, and quantifying these fracture modes.

  16. Modeling of viscoelastic behavior of dental chemically activated resin composites during curing.

    PubMed

    Dauvillier, B S; Hübsch, P F; Aarnts, M P; Feilzer, A J

    2001-01-01

    Shrinkage stresses generated in dental resin composites during curing are among the major problems in adhesive dentistry, because they interfere with the integrity of the restored tooth. The aim of this study was to find a mechanical model to describe the viscoelastic behavior of a two-paste resin composite during curing, to aid our understanding of the process of shrinkage stress development. In this study, stress-strain data on Clearfil F2 during curing were obtained by a dynamic test method and analyzed using three mechanical models (Maxwell, Kelvin, and the Standard Linear Solid model). With a modeling procedure, the model's stress response was compared with the experimental stress data, and the material parameters were calculated. On the basis of the modeling and evaluation results, a model for describing the viscoelastic behavior of the shrinking resin composite was selected. The validation results showed that the modeling procedure is free of error, and that it was capable of finding material parameters associated with a two-parametric model with a high degree of accuracy. The viscoelastic behavior of the shrinking resin composite, as excited by the conditions of the test method, cannot be described by a single mechanical model. In the early stage of curing, the most accurate prediction was achieved by the Maxwell model, while during the remainder of the curing process the Kelvin model can be used to describe the viscoelastic behavior of the two-paste resin composite. PMID:11152993

  17. Dry Sliding Wear Behavior of Fly Ash Cenosphere/AZ91D Mg Alloy Composites

    NASA Astrophysics Data System (ADS)

    Yu, S. R.; Huang, Z. Q.

    2014-10-01

    Fly ash cenosphere/AZ91D Mg alloy (FAC/AZ91D) composites were prepared using stir casting method. The effects of the applied load, the wearing time, and the diameter and the content of fly ash cenosphere on the wear behavior of the composites were investigated under dry sliding condition. The results showed the wear resistance of FAC/AZ91D composites is generally better than that of AZ91D Mg alloy. The mass fraction and diameter of FAC have important effects on the wear resistance of the composites, and the wear resistance of the composites is excellent when the mass fraction and diameter of FAC are moderate. When the mass fraction and diameter of FAC are more than the critical values, the wear resistance of the composites lowers again. The wear resistance of the composites decreases with the increase in the applied load. The relationship between the worn mass loss and the applied load is nonlinear. When the applied load is smaller, the worn mass loss of the composites increases rapidly with the increase of the applied load. These research results show that the composites have broad application prospects under dry sliding wear condition, and they can provide guidance for the selection of the raw materials, the structure design, and the application conditions of the composites.

  18. An overview of the crash dynamics failure behavior of metal and composite aircraft structures

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Boitnott, Richard L.; Fasanella, Edwin L.; Jones, Lisa E.

    1991-01-01

    An overview of failure behavior results is presented from some of the crash dynamics research conducted with concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. Experimental and analytical data are presented that indicate some general trends in the failure behavior of a class of composite structures that includes fuselage panels, individual fuselage sections, fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame stringer structure. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models.

  19. Failure behavior of generic metallic and composite aircraft structural components under crash loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Robinson, Martha P.

    1990-01-01

    Failure behavior results are presented from crash dynamics research using concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs incorporating improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures including individual fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models.

  20. Modeling of stress/strain behavior of fiber-reinforced ceramic matrix composites including stress redistribution

    NASA Technical Reports Server (NTRS)

    Mital, Subodh K.; Murthy, Pappu L. N.; Chamis, Christos C.

    1994-01-01

    A computational simulation procedure is presented for nonlinear analyses which incorporates microstress redistribution due to progressive fracture in ceramic matrix composites. This procedure facilitates an accurate simulation of the stress-strain behavior of ceramic matrix composites up to failure. The nonlinearity in the material behavior is accounted for at the constituent (fiber/matrix/interphase) level. This computational procedure is a part of recent upgrades to CEMCAN (Ceramic Matrix Composite Analyzer) computer code. The fiber substructuring technique in CEMCAN is used to monitor the damage initiation and progression as the load increases. The room-temperature tensile stress-strain curves for SiC fiber reinforced reaction-bonded silicon nitride (RBSN) matrix unidirectional and angle-ply laminates are simulated and compared with experimentally observed stress-strain behavior. Comparison between the predicted stress/strain behavior and experimental stress/strain curves is good. Collectively the results demonstrate that CEMCAN computer code provides the user with an effective computational tool to simulate the behavior of ceramic matrix composites.

  1. Group compositional changes impact the social and feeding behaviors of captive hamadryas baboons (Papio hamadryas hamadryas).

    PubMed

    Ryan, Amy M; Hauber, Mark E

    2016-01-01

    The formation and modification of social groups in captivity are delicate management tasks. The ability for personnel to anticipate changes in group dynamics following compositional changes can increase the likelihood of successful management with minimized injury or social instability. Hamadryas baboons (Papio hamadryas hamadryas) have a distinctive multi-level social system comprising of one-male units (OMUs) that can make it difficult to apply knowledge from other primates' multi-female/multi-male social structure to changes imposed onto captive hamadryas baboon groups. We conducted an observational study of the behavioral impacts following the introduction of two females into the group of hamadryas baboons at the Wildlife Conservation Society's Prospect Park Zoo in NY to test hypotheses about the relationships between changes in group composition and social and feeding behavior. Generalized linear mixed models demonstrated that social interactions significantly increased following the compositional changes, even in groups that only experienced member removals. The increase in affiliative social behavior observed suggests that during times of social stress or uncertainty, hamadryas baboons may employ social behavior as a tension-reducing mechanism to negotiate relationships as opposed to using aggression to engage in competitions for ranks and resources. The observed response to compositional changes implies that hamadryas baboons may respond with less aggression than do other Old World monkey species and that levels of affiliative behavior may be a more accurate metric for evaluating introduction success in hamadryas baboons. PMID:26828857

  2. Learning from experience: Event-related potential correlates of reward processing, neural adaptation, and behavioral choice

    PubMed Central

    Walsh, Matthew M.; Anderson, John R.

    2012-01-01

    To behave adaptively, we must learn from the consequences of our actions. Studies using event-related potentials (ERPs) have been informative with respect to the question of how such learning occurs. These studies have revealed a frontocentral negativity termed the feedback-related negativity (FRN) that appears after negative feedback. According to one prominent theory, the FRN tracks the difference between the values of actual and expected outcomes, or reward prediction errors. As such, the FRN provides a tool for studying reward valuation and decision making. We begin this review by examining the neural significance of the FRN. We then examine its functional significance. To understand the cognitive processes that occur when the FRN is generated, we explore variables that influence its appearance and amplitude. Specifically, we evaluate four hypotheses: (1) the FRN encodes a quantitative reward prediction error; (2) the FRN is evoked by outcomes and by stimuli that predict outcomes; (3) the FRN and behavior change with experience; and (4) the system that produces the FRN is maximally engaged by volitional actions. PMID:22683741

  3. Highly Dynamic and Adaptive Traffic Congestion Avoidance in Real-Time Inspired by Honey Bee Behavior

    NASA Astrophysics Data System (ADS)

    Wedde, Horst F.; Lehnhoff, Sebastian; van Bonn, Bernhard; Bay, Z.; Becker, S.; Böttcher, S.; Brunner, C.; Büscher, A.; Fürst, T.; Lazarescu, A. M.; Rotaru, E.; Senge, S.; Steinbach, B.; Yilmaz, F.; Zimmermann, T.

    Traffic congestions have become a major problem in metropolitan areas world-wide, within and between cities, to an extent where they make driving and transportation times largely unpredictable. Due to the highly dynamic character of congestion building and dissolving this phenomenon appears even to resist a formal treatment. Static approaches, and even more their global management, have proven counterproductive in practice. Given the latest progress in VANET technology and the remarkable commercially driven efforts like in the European C2C consortium, or the VSC Project in the US, allow meanwhile to tackle various aspects of traffic regulation through VANET communication. In this paper we introduce a novel, completely decentralized multi-agent routing algorithm (termed BeeJamA) which we have derived from the foraging behavior of honey bees. It is highly dynamic, adaptive, robust, and scalable, and it allows for both avoiding congestions, and minimizing traveling times to individual destinations. Vehicle guidance is provided well ahead of every intersection, depending on the individual speeds. Thus strict deadlines are imposed on, and respected by, the BeeJamA algorithm. We report on extensive simulation experiments which show the superior performance of BeeJamA over conventional approaches.

  4. Adapted cognitive-behavioral therapy for religious individuals with mental disorder: a systematic review.

    PubMed

    Lim, Caroline; Sim, Kang; Renjan, Vidhya; Sam, Hui Fang; Quah, Soo Li

    2014-06-01

    Cognitive-behavioral therapy (CBT) is considered an evidence-based psychological intervention for various mental disorders. However, mental health clinicians should be cognizant of the population that was used to validate the intervention and assess its acceptability to a target group that is culturally different. We systematically reviewed published empirical studies of CBT adapted for religious individuals with mental disorder to determine the extent to which religiously modified CBT can be considered an empirically supported treatment following the criteria delineated by the American Psychological Association Task Force on Promotion and Dissemination of Psychological Procedures. Overall, nine randomized controlled trials and one quasi-experimental study were included that compared the effectiveness of religiously modified CBT to standard CBT or other treatment modalities for the treatment of depressive disorders, generalized anxiety disorder, and schizophrenia. The majority of these studies either found no difference in effectiveness between religiously modified CBT compared to standard CBT or other treatment modalities, or early effects that were not sustained. Considering the methodological limitations of the reviewed studies, religiously modified CBT cannot be considered a well-established psychological intervention for the treatment of the foregoing mental disorders following the a priori set criteria at this juncture. Nevertheless, melding religious content with CBT may be an acceptable treatment modality for individuals with strong religious convictions. PMID:24813028

  5. Morphological and behavioral evidence for adaptive diversification of sympatric Hawaiian limpets (Cellana spp.).

    PubMed

    Bird, Christopher E

    2011-09-01

    The endemic Hawaiian limpets (Cellana exarata, Cellana sandwicensis, and Cellana talcosa), reside at different elevations on wave-exposed rocky shores and comprise a monophyletic lineage that diversified within Hawai'i. Here, I report phenotypic differences in shell, soft tissue, and behavioral characters among these limpets and discuss their potential utility in exploiting their respective niches. The high-shore limpet, C. exarata, is characterized by a tall round shell, short mantle tentacles, and long evasion distance when confronted by a predatory gastropod. The mid-shore limpet, C. sandwicensis, is characterized by a shorter oblong shell, long mantle tentacles, and a short evasion distance when confronted by a predatory snail. The low-shore, shallow-subtidal limpet, C. talcosa, is characterized by a flat shell that is thin in juveniles and disproportionately massive in large adults (relative to the other two species), and mantle tentacles of varying lengths (some individuals exhibit short tentacles, some long). These species-specific suites of characters are likely to confer specific fitness advantages on the high shore (C. exarata) where thermal and desiccation stress is severe, on the mid shore (C. sandwicensis) where hydrodynamic forces are severe, and on the low-shallow subtidal shore (C. talcosa) where pelagic predators have free access to the limpets. These data add to the growing body of evidence for adaptive diversification and speciation in the Hawaiian Cellana, and in marine species in general. PMID:21700576

  6. Behavior of composite and polycarbonate plate under impact

    NASA Astrophysics Data System (ADS)

    Denneulin, S.; Viot, P.

    2010-06-01

    The use of filled composite materials in passive safety structure has significantly increased recently because of their low specific mass, stiffness and energy absorption capacities. However those new light weight materials are supposed to exhibit equal or higher performances than classical ones. Therefore interesting applications by using those materials can be thought about like in the manufacturing of aeronautical helmets. Constituted of an outer shell and an inner foam structure, helmet must protect pilots from an impact by absorbing energy as much as possible and avoid contact between head and impactor. Nowadays different standards describe the minimum required performance for shock attenuation and penetration resistance of helmets [1]. These standards are based on acceleration time history measurements recorded from an accelerometer located at the headform center of mass. For aeronautical standard, acceleration peak value is the only one parameter concerning shock attenuation. Its value must not exceed 300 g, where g = 9.81 m.s-2. Concerning penetration resistance, no contact can be accepted between the penetrating striker and the headform. The outer shell of the helmet has to resist penetration in order to absorb and to extend the input energy over the foam. The most important part of energy is dissipated by polymeric foam through collapse processes under impact [2]. Nevertheless a significant part of energy (one third [3, 4]) can be dissipated by the plastic deformation of the shell and the occurrence of damage mechanisms. To obtain different dissipative phenomena, various materials were studied: a) Three different kinds of polycarbonate were used. This type of material is well known for its large viscoplastic deformations without any significant hardening. In other words it is a very good candidate for helmet application because of high specific energy dissipation and a stress cut-off effect. Moreover a larger affected zone is expected for filled

  7. Vineland Adaptive Behavior Scales: II Profile of Young Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Yang, Sabrina; Paynter, Jessica M.; Gilmore, Linda

    2016-01-01

    Adaptive behaviour is a crucial area of assessment for individuals with Autism Spectrum Disorder (ASD). This study examined the adaptive behaviour profile of 77 young children with ASD using the Vineland-II, and analysed factors associated with adaptive functioning. Consistent with previous research with the original Vineland a distinct autism…

  8. A New Approach to the Measurement of Adaptive Behavior: Development of the PEDI-CAT for Children and Youth with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kramer, Jessica M.; Coster, Wendy J.; Kao, Ying-Chia; Snow, Anne; Orsmond, Gael I.

    2012-01-01

    The use of current adaptive behavior measures in practice and research is limited by their length and need for a professional interviewer. There is a need for alternative measures that more efficiently assess adaptive behavior in children and youth with autism spectrum disorders (ASDs). The Pediatric Evaluation of Disability Inventory-Computer…

  9. Adaptive Behavior Assessment System-II Parent/Primary Caregiver Form: Ages 0-5--Its Factor Structure and Other Implications for Practice

    ERIC Educational Resources Information Center

    Oakland, Thomas; Algina, James

    2011-01-01

    A child's acquisition of adaptive behavior and skills may constitute his or her most important goal during infancy and early childhood. In addition, adaptive behavior data often are required when making decisions under Part C of the 2004 Individuals With Disabilities Education Improvement Act. This study reports the results of a factor analysis of…

  10. Oxidation Behavior of Carbon Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2008-01-01

    OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

  11. Fracture behavior of unidirectional boron/aluminum composite laminates

    NASA Technical Reports Server (NTRS)

    Goree, J. G.; Jones, W. F.

    1983-01-01

    An experiment was conducted to verify the results of mathematical models which predict the stresses and displacements of fibers and the amount of damage growth in a center-notched lamina as a function of the applied remote stress and the matrix and fiber material properties. A brittle lacquer coating was used to detect the yielding in the matrix while X-ray techniques were used to determine the number of broken fibers in the laminate. The notched strengths and the amounts of damage found in the specimens agree well with those predicted by the mathematical model. It is shown that the amount of damage and the crack opening displacement does not depend strongly on the number of plies in the laminate for a given notch width. By heat-treating certain laminates to increase the yield stress of the alumina matrix, the effect of different matrix properties on the fracture behavior was investigated. The stronger matrix is shown to weaken the notched laminate by decreasing the amount of matrix damage, thereby making the laminate more notch sensitive.

  12. Behavioral adaptations imply a direct link between ecological specialization and reproductive isolation in a sympatrically diverging ground beetle.

    PubMed

    Van Belleghem, Steven M; De Wolf, Katrien; Hendrickx, Frederik

    2016-08-01

    Adaptation to a previously unoccupied niche within a single population is one of the most contentious topics in evolutionary biology as it assumes the simultaneous evolution of ecologically selected and preference traits. Here, we demonstrate behavioral adaptation to contrasting hydrological regimes in a sympatric mosaic of Pogonus chalceus beetle populations, and argue that this adaptation may result in nonrandom gene flow. When exposed to experimental inundations, individuals from tidal marshes, which are naturally subjected to frequent but short floods, showed a higher propensity to remain submerged compared to individuals from seasonal marshes that are inundated for several months. This adaptive behavior is expected to decrease the probability that individuals will settle in the alternative habitat, resulting in spatial sorting and reproductive isolation of both ecotypes. Additionally, we show that this difference in behavior is induced by the environmental conditions experienced by the beetles during their nondispersive larval stages. Hence, accidental or forced ovipositioning in the alternative habitat may induce both an increased performance and preference to the natal habitat type. Such plastic traits could play an important role in the most incipient stages of divergence with gene flow. PMID:27405686

  13. Creep behavior of tungsten/niobium and tungsten/niobium-1 percent zirconium composites

    NASA Technical Reports Server (NTRS)

    Petrasek, D. W.; Titran, R. H.

    1988-01-01

    A study was conducted to determine the feasibility of using tungsten fiber reinforced niobium or niobium-1 percent zirconium matrix composites to meet the anticipated increased temperature and creep resistance requirements imposed by advanced space power systems. The results obtained on the short time tensile properties indicated that W/Nb composites showed significant improvements in high temperature strength and offer significant mass reductions for high temperature space power systems. The prime material requirement for space power systems applications is long time creep resistance. A study was conducted to determine the effect of high temperature exposure on the properties of these composites, with emphasis upon their creep behavior at elevated temperatures.

  14. An experimental investigation on the three-point bending behavior of composite laminate

    NASA Astrophysics Data System (ADS)

    A, Azzam; W, Li

    2014-08-01

    The response of composite laminate structure to three-point bending load was investigated by subjecting two types of stacking sequences of composite laminate structure by using electronic universal tester (Type: WDW-20) machine. Optical microscope was selected in order to characterize bending damage, delamination, and damage shapes in composite laminate structures. The results showed that the [0/90/-45/45]2s exhibits a brittle behavior, while other laminates exhibit a progressive failure mode consisting of fiber failure, debonding (splitting), and delamination. The [45/45/90/0]2s laminate has a highly nonlinear load- displacement curve due to compressive yielding.

  15. Tensile Behavior of Tungsten/Niobium Composites at 1300 to 1600 K

    NASA Technical Reports Server (NTRS)

    Yun, Hee Mann; Titran, Robert H.

    1989-01-01

    The tensile behavior of continuous tungsten fiber reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components as well as of the composites were measured and were compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for ST300/Nb (i.e., stronger composite strength than the ROM) and negative or zero deviations for 218/Nb.

  16. Tensile behavior of tungsten/niobium composites at 1300--1600 K

    SciTech Connect

    Yun, Hee Mann ); Titran, R.H. . Lewis Research Center)

    1989-01-01

    The tensile behavior of continuous-tungsten-fiber-reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components as well as the composites were measured and were compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for ST300/Nb (i.e., stronger composite strength than the ROM) and negative or zero deviations for 218/Nb. 16 refs., 13 figs., 5 tabs.

  17. High-Cycle Fatigue Behavior of a Nicalon(tm)/Si-N-C Composite

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Kalluri, Sreeramesh; Kantzos, Peter T.

    1999-01-01

    Elevated temperature, high-cycle fatigue behavior of a woven SiC/Si-N-C ceramic matrix composite system was investigated at 910 C. High frequency (100 Hz) fatigue tests were conducted in air on specimens machined from the composite system, A power-law type fatigue life relationship adequately characterized the high-cycle fatigue data generated in the study. Post failure fractographic and metallographic studies were performed to document the fatigue crack initiation regions and damage mechanisms in the composite system. Fatigue cracks initiated primarily from the corners of the specimens and propagated along the 90 degree fiber tows.

  18. Overview Of Structural Behavior and Occupant Responses from Crash Test of a Composite Airplane

    NASA Technical Reports Server (NTRS)

    Jones, Lisa E.; Carden, Huey D.

    1995-01-01

    As part of NASA's composite structures crash dynamics research, a general aviation aircraft with composite wing, fuselage and empennage (but with metal subfloor structure) was crash tested at the NASA Langley Research Center Impact Research Facility. The test was conducted to determine composite aircraft structural behavior for crash loading conditions and to provide a baseline for a similar aircraft test with a modified subfloor. Structural integrity and cabin volume were maintained. Lumbar loads for dummy occupants in energy absorbing seats wer substantially lower than those in standard aircraft seats; however, loads in the standard seats were much higher that those recorded under similar conditions for an all-metallic aircraft.

  19. Effect of Ductile Agents on the Dynamic Behavior of SiC3D Network Composites

    NASA Astrophysics Data System (ADS)

    Zhu, Jingbo; Wang, Yangwei; Wang, Fuchi; Fan, Qunbo

    2016-07-01

    Co-continuous SiC ceramic composites using pure aluminum, epoxy, and polyurethane (PU) as ductile agents were developed. The dynamic mechanical behavior and failure mechanisms were investigated experimentally using the split Hopkinson pressure bar (SHPB) method and computationally by finite element (FE) simulations. The results show that the SiC3D/Al composite has the best overall performance in comparison with SiC3D/epoxy and SiC3D/PU composites. FE simulations are generally consistent with experimental data. These simulations provide valuable help in predicting mechanical strength and in interpreting the experimental results and failure mechanisms. They may be combined with micrographs for fracture characterizations of the composites. We found that interactions between the SiC phase and ductile agents under dynamic compression in the SHPB method are complex, and that interfacial condition is an important parameter that determines the mechanical response of SiC3D composites with a characteristic interlocking structure during dynamic compression. However, the effect of the mechanical properties of ductile agents on dynamic behavior of the composites is a second consideration in the production of the composites.

  20. Solid Particle Erosion Behaviors of Carbon-Fiber Epoxy Composite and Pure Titanium

    NASA Astrophysics Data System (ADS)

    Cai, Feng; Gao, Feng; Pant, Shashank; Huang, Xiao; Yang, Qi

    2016-01-01

    Rotor blades of Bell CH-146 Griffon helicopter experience excessive solid particle erosion at low altitudes in desert environment. The rotor blade is made of an advanced light-weight composite which, however, has a low resistance to solid particle erosion. Coatings have been developed and applied to protect the composite blade. However, due to the influence of coating process on composite material, the compatibility between coating and composite base, and the challenges of repairing damaged coatings as well as the inconsistency between the old and new coatings, replaceable thin metal shielding is an alternative approach; and titanium, due to its high-specific strength and better formability, is an ideal candidate. This work investigates solid particle erosion behaviors of carbon-fiber epoxy composite and titanium in order to assess the feasibility of titanium as a viable candidate for erosion shielding. Experiment results showed that carbon-fiber epoxy composite showed a brittle erosion behavior, whereas titanium showed a ductile erosion mode. The erosion rate on composite was 1.5 times of that on titanium at impingement angle 15° and increased to 5 times at impact angle 90°.

  1. Strength and fracture behavior of aluminide matrix composites with ceramic fibers

    SciTech Connect

    Inoue, M.; Suganuma, K.; Niihara, K.

    1999-07-01

    This paper investigates the fracture behavior of FeAl and Ni{sub 3}Al matrix composites with ceramic continuous fibers 8.5--10 {micro}m in diameter. When stress is applied to these composites, multiple-fracture of fibers predominantly occurs before matrix cracking, because the load carried by the fibers reaches their fracture strength. Fragments which remain longer than the critical length can provide significant strengthening through load bearing even though fiber breaking has occurred. The ultimate fracture strength of the composites also depends on stress relaxation by plastic deformation of the matrix at a crack tip in the multiple-fractured fibers. Ductilizing of the matrix by B doping improves the ultimate strength at ambient temperatures in both composites. However, their mechanical properties at elevated temperatures are quite different. In the case of Ni{sub 3}Al matrix composites, embrittlement of the matrix is undesirable for high strength and reliability at 873--973 K.

  2. Preparation and tribological behavior of Ni-graphene composite coating under room temperature

    NASA Astrophysics Data System (ADS)

    Chen, Juanjuan; Li, Jianliang; Xiong, Dangsheng; He, Yong; Ji, Yujuan; Qin, Yongkun

    2016-01-01

    In this paper, Ni-graphene composite coatings with different graphene addition amounts were prepared on 45 steel disk by using dipulse composite electrodeposition technology. Meanwhile, the influence of plating time, bath temperature and load on friction and wear of the coating was studied. The tribological behavior of composite coating was tested against a Si3N4 ceramic ball under dry condition. Cross-sectional morphologies showed that Ni-graphene coating was successfully coated on the substrate with an average thickness of 85 ± 5 μm. XRD analysis concluded that with the increase of addition amount of graphene, the average crystallite size of coating decreased. EDS analyses and Raman spectra proved the presence of graphene. Friction coefficient of composite coating decreased with the increase of graphene addition amounts, while the hardness increased. Meanwhile, the wear resistance of composite coating improved. The optimum experimental conditions were obtained.

  3. Adaptive Optics with a Liquid-Crystal-on-Silicon Spatial Light Modulator and Its Behavior in Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Shirai, Tomohiro; Takeno, Kohei; Arimoto, Hidenobu; Furukawa, Hiromitsu

    2009-07-01

    An adaptive optics system with a brand-new device of a liquid-crystal-on-silicon (LCOS) spatial light modulator (SLM) and its behavior in in vivo imaging of the human retina are described. We confirmed by experiments that closed-loop correction of ocular aberrations of the subject's eye was successfully achieved at the rate of 16.7 Hz in our system to obtain a clear retinal image in real time. The result suggests that an LCOS SLM is one of the promising candidates for a wavefront corrector in a prospective commercial ophthalmic instrument with adaptive optics.

  4. Rate dependent stress-strain behavior of advanced polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.

    1991-01-01

    The formulation of an elastic/viscoplastic constitutive model which was used to predict the measured behavior of graphite/thermoplastic and graphite/bismaleimide composite materials at elevated temperature is described. The model incorporates the concepts of overstress and effective strain/strain to provide a simple formulation which was able to account for material behavior under monotonic tension or compression loads over a temperature range of 23 to 200 C. Observed behavior such as stress relaxation and steady state creep, in off-axis tension and compression tests, were predicted by the model. Material constants required by the model were extracted from simple off-axis test data.

  5. The influence of FRCs reinforcement on marginal adaptation of CAD/CAM composite resin endocrowns after simulated fatigue loading.

    PubMed

    Rocca, Giovanni Tommaso; Saratti, Carlo Massimo; Poncet, Antoine; Feilzer, Albert J; Krejci, Ivo

    2016-05-01

    To evaluate the marginal adaptation of endodontically treated molars restored with CAD/CAM composite resin endocrowns either with or without reinforcement by fibre reinforced composites (FRCs), used in different configurations. 32 human endodontically treated molars were cut 2 mm over the CEJ. Two interproximal boxes were created with the margins located 1 mm below the CEJ (distal box) and 1 mm over the CEJ (mesial box). All specimens were divided in four groups (n = 8). The pulp chamber was filled with: group 1 (control), hybrid resin composite (G-aenial Posterior, GC); group 2, as group 1 but covered by 3 meshes of E-glass fibres (EverStick NET, Stick Tech); group 3, FRC resin (EverX Posterior, GC); group 4, as group 3 but covered by 3 meshes of E-glass fibres. The crowns of all teeth were restored with CAD/CAM composite resin endocrowns (LAVA Ultimate, 3M). All specimens were thermo-mechanically loaded in a computer-controlled chewing machine (600,000 cycles, 1.6 Hz, 49 N and simultaneously 1500 thermo-cycles, 60 s, 5-55 °C). Marginal analysis before and after the loading was carried out on epoxy replicas by SEM at 200× magnification. For all the groups, the percentage values of perfect marginal adaptation after loading were always significantly lower than before loading (p < 0.05). The marginal adaptation before and after loading was not significantly different between the experimental groups (p > 0.05). Within the limitations of this in vitro study, the use of FRCs to reinforce the pulp chamber of devitalized molars restored with CAD/CAM composite resin restorations did not significantly influenced their marginal quality. PMID:25854165

  6. Unique failure behavior of metal/composite aircraft structural components under crash type loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.

    1990-01-01

    Failure behavior results are presented on some of the crash dynamics research conducted with concepts of aircraft elements and substructure which have not necessarily been designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash type loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the thread of similarity in behavior is telling the designer and dynamists a great deal about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures.

  7. Composite behavior analysis for video surveillance using hierarchical dynamic Bayesian networks

    NASA Astrophysics Data System (ADS)

    Cheng, Huanhuan; Shan, Yong; Wang, Runsheng

    2011-03-01

    Analyzing composite behaviors involving objects from multiple categories in surveillance videos is a challenging task due to the complicated relationships among human and objects. This paper presents a novel behavior analysis framework using a hierarchical dynamic Bayesian network (DBN) for video surveillance systems. The model is built for extracting objects' behaviors and their relationships by representing behaviors using spatial-temporal characteristics. The recognition of object behaviors is processed by the DBN at multiple levels: features of objects at low level, objects and their relationships at middle level, and event at high level, where event refers to behaviors of a single type object as well as behaviors consisting of several types of objects such as ``a person getting in a car.'' Furthermore, to reduce the complexity, a simple model selection criterion is addressed, by which the appropriated model is picked out from a pool of candidate models. Experiments are shown to demonstrate that the proposed framework could efficiently recognize and semantically describe composite object and human activities in surveillance videos.

  8. Matrix cracking and creep behavior of monolithic zircon and zircon silicon carbide fiber composites

    NASA Astrophysics Data System (ADS)

    Anandakumar, Umashankar

    In this study, the first matrix cracking behavior and creep behavior of zircon matrix silicon carbide fiber composites were studied, together with the fracture and creep behavior of the monolithic zircon. These behaviors are of engineering and scientific importance, and the study was aimed at understanding the deformation mechanisms at elevated temperatures. The first matrix cracking behavior of zircon matrix uniaxially reinforced with silicon carbide fiber (SCS-6) composites and failure behavior of monolithic zircon were studied as a function of temperature (25°C, 500°C, and 1200°C) and crack length in three point bending mode. A modified vicker's indentation technique was used to vary the initial crack length in monolithic and composite samples. The interfacial shear strength was measured at these temperatures from matrix crack saturation spacing. The composites exhibited steady state and non steady state behaviors at the three different temperatures as predicted by theoretical models, while the failure stress of zircon decreased with increasing stress. The intrinsic properties of the composites were used to numerically determine the results predicted by three different matrix cracking models based on a fracture mechanics approach. The analysis showed that the model based on crack bridging analysis was valid at 25°C and 500°C, while a model based on statistical fiber failure was valid at 1200°C. Microstructural studies showed that fiber failure in the crack wake occurred at or below the matrix cracking stress at 1200°C, and no fiber failure occurred at the other two temperatures, which validated the results predicted by the theoretical models. Also, it was shown that the interfacial shear stress corresponding to debonding determined the matrix cracking stress, and not the frictional shear stress. This study showed for the first time, the steady state and non-steady state matrix cracking behavior at elevated temperatures, the difference in behavior between

  9. Teaching Paragraph Composition to Students with Emotional/Behavioral Disorders Using the Simultaneous Prompting Procedure

    ERIC Educational Resources Information Center

    Hudson, Tina Marlene; Hinkson-Lee, Kim; Collins, Belva

    2013-01-01

    The purpose of this study was to examine the effectiveness of the simultaneous prompting procedure in teaching paragraph composition to 4, 5th grade students identified with emotional behavioral disorder (EBD) and attention-deficit hyperactivity disorder (ADHD). The instructor taught students how to construct and proofread a 5-sentence paragraph…

  10. Bond and low cycle fatigue behavior of thermoset composite reinforcing for the concrete industry

    SciTech Connect

    Barnes, B.

    1990-09-21

    This thesis encompasses two separate research projects. The first project, described in Chapter 2 was a project investigating the fatigue behavior of thermoset Fiber Composite (FC) sandwich wall ties. The second research project detailed in this thesis was a project studying the bond and tensile properties of FC rod and FC fibers.

  11. Treatment of addiction and addiction-related behavior using a composition of topiramate

    DOEpatents

    Dewey, Stephen L.; Brodie, Jonathan D.; Ashby, Jr., Charles R.

    2005-06-14

    The present invention relates to the use of a composition that increases central nervous system GABA levels in a mammal, for the treatment of addiction to drugs of abuse and modification of behavior associated with addiction to drugs of abuse in said mammal.

  12. Characterization of percolation behavior in conductor-dielectric 0-3 composites

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Bass, Patrick; Dang, Zhi-Min; Cheng, Z.-Y.

    2014-12-01

    The equation ɛeff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (ɛeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor-dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.

  13. Second-order two-scale method for bending behaviors of composite plate with periodic configuration

    NASA Astrophysics Data System (ADS)

    Zhu, Guoqing; Cui, Junzhi

    2010-06-01

    In this paper, the second-order two-scale analysis method for bending behaviors of the plate made from composites with 3-D periodic configuration is presented by means of construction way. It can capture the microscopic 3-D mechanics behaviors caused from 3-D micro-structures. First, directly starting from the 3-D elastic plate model of composite materials with 3-D periodic configuration, three cell models are defined, and correspondingly the three classes of cell functions only defined on 3 normalized cells are constructed. And then, the effective homogenization parameters of composites are calculated from those local functions, it leads to a 2-D homogenized laminar plate problem. Next, to solve it the homogenization solution is obtained. Finally, the second-order two-scale solution is constructed from the micro-cell functions and the homogenization solution.

  14. Second-Order Two-Scale Method for Bending Behaviors of Composite Plate with Periodic Configuration

    NASA Astrophysics Data System (ADS)

    Zhu, Guoqing; Cui, Junzhi

    2010-05-01

    In this paper, the second-order two-scale analysis method for bending behaviors of the plate made from composites with 3-D periodic configuration is presented by means of construction way. It can capture the microscopic 3-D mechanics behaviors caused from 3-D micro-structures. First, directly starting from the 3-D elastic plate model of composite materials with 3-D periodic configuration, three cell models are defined, and correspondingly the three classes of cell functions only defined on 3 normalized cells are constructed. And then, the effective homogenization parameters of composites are calculated from those local functions, it leads to a 2-D homogenized laminar plate problem. Next, to solve it the homogenization solution is obtained. Finally, the second-order two-scale solution is constructed from the micro-cell functions and the homogenization solution.

  15. Thermal and mechanical behavior of metal matrix and ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Kennedy, John M. (Editor); Moeller, Helen H. (Editor); Johnson, W. S. (Editor)

    1990-01-01

    The present conference discusses local stresses in metal-matrix composites (MMCs) subjected to thermal and mechanical loads, the computational simulation of high-temperature MMCs' cyclic behavior, an analysis of a ceramic-matrix composite (CMC) flexure specimen, and a plasticity analysis of fibrous composite laminates under thermomechanical loads. Also discussed are a comparison of methods for determining the fiber-matrix interface frictional stresses of CMCs, the monotonic and cyclic behavior of an SiC/calcium aluminosilicate CMC, the mechanical and thermal properties of an SiC particle-reinforced Al alloy MMC, the temperature-dependent tensile and shear response of a graphite-reinforced 6061 Al-alloy MMC, the fiber/matrix interface bonding strength of MMCs, and fatigue crack growth in an Al2O3 short fiber-reinforced Al-2Mg matrix MMC.

  16. The influence of fiber waviness on the compressive behavior of unidirectional continuous fiber composites

    NASA Technical Reports Server (NTRS)

    Highsmith, Alton L.; Davis, John J.; Helms, Kayleen L. E.

    1992-01-01

    The influence of fiber waviness and matrix nonlinearity on the compressive behavior of continuous fiber composites is studied. A micromechanics model based on the kinematics of the fibers has been developed to predict the behavior of unidirectional composites with initially wavy fibers under compressive loads. The initial waviness has been idealized as sinusoidal. Nonlinear shear behavior of the matrix has been included. Because the shear strain in the matrix is a function of position, the deformed shape of the fibers differs from the initial shape. Therefore, the deformed fiber shape is represented by a sine series. Fiber waviness and matrix shear properties have been determined experimentally for T650-42/Radel C under several conditions. These experimental data have been used as input into the analytical model. Predicted compressive response is in reasonable agreement with experimental data.

  17. Behavior, milk yield, and milk composition of machine-and hand-milked Murgese mares.

    PubMed

    Caroprese, M; Albenzio, M; Marino, R; Muscio, A; Zezza, T; Sevi, A

    2007-06-01

    A 25-d trial was performed to assess the effects of machine and hand milking on behavior, and milk yield and composition of mares; the trial involved 8 Murgese mares. Milk yield was higher (7.69 vs. 4.91 kg) and milking time was shorter (1.80 vs. 5.40 min) in machine-milked than in hand-milked mares. Machine milking of mares also resulted in a greater fat content of milk (1.63%) than did hand milking (1.06%). Milking system did not affect casein content, nitrogen fractions, or somatic cell counts. No differences in behavioral activities and in response to humans emerged. Results indicate that machine milking of mares could improve the yield and gross composition of horse milk, without adverse consequences on mare behavior and response to humans. PMID:17517717

  18. Influence of the interface and fiber spacing on the fracture behavior of glass matrix composites

    SciTech Connect

    Matikas, T.E.; Karpur, P.; Kim, R.; Dutton, R.

    1995-09-01

    In this work, a nondestructive methodology is provided to determine the presence of microcracking in unidirectional SiC fiber reinforced brittle (borosilicate glass) matrix composites and to detect internal cracks in the composites that did not reach the surface of the specimen. The methodology is based on a combination of several ultrasonic techniques including shear back reflectivity (SBR), back-reflected surface wave imaging and acoustic microscopy. The composites used in this study were made with controlled fiber spacing consisting of regular arrays of either TiB{sub 2} coated SIGMA 1240 or carbon coated SCS-6 monofilament fibers in a series of borosilicate glasses. The combinations of different constituents provided composite samples with various fiber matrix interface properties. The composites were subjected to axial loading, and the stress in the composite when matrix cracking first occurs was determined and compared with theoretical values provided by a semi-empirical model which can assume either a completely bonded (i.e. perfect) or completely unbonded (i.e. pure slip) fiber-matrix interface. Results from the tensile data for different glass matrix composite systems were also compared with data of interface elastic property evaluation using ultrasonic SBR technique, allowing investigation f the influence of the fiber-matrix interface elastic property, the volume fraction of the fibers, and the state of radial residual stresses at the interface on the fracture behavior of glass matrix composites.

  19. Adapting Phonological Awareness Interventions for Children With Down Syndrome Based on the Behavioral Phenotype: A Promising Approach?

    PubMed

    Lemons, Christopher J; King, Seth A; Davidson, Kimberly A; Puranik, Cynthia S; Fulmer, Deborah; Mrachko, Alicia A; Partanen, Jane; Al Otaiba, Stephanie; Fidler, Deborah J

    2015-08-01

    Many children with Down syndrome demonstrate deficits in phonological awareness, a prerequisite to learning to read in an alphabetic language. The purpose of this study was to determine whether adapting a commercially available phonological awareness program to better align with characteristics associated with the behavioral phenotype of Down syndrome would increase children's learning of phonological awareness, letter sounds, and words. Five children with Down syndrome, ages 6 to 8 years, participated in a multiple baseline across participants single case design experiment in which response to an adapted phonological awareness intervention was compared with response to the nonadapted program. Results indicate a functional relation between the adapted program and phonological awareness. Suggestions for future research and implications for practice are provided. PMID:26214557

  20. Adaptive Coping Reduces the Impact of Community Violence Exposure on Violent Behavior among African American and Latino Male Adolescents

    ERIC Educational Resources Information Center

    Brady, Sonya S.; Gorman-Smith, Deborah; Henry, David B.; Tolan, Patrick H.

    2008-01-01

    This study examined whether coping moderated the impact of community violence exposure (CVE) on violent behavior among 285 urban African American and Latino adolescent males assessed annually across 5 years. Composites indicating overall CVE (having knowledge of others' victimization, witnessing violence, direct victimization) and approach to…