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Sample records for n-vector model collective

  1. Entanglement and RG in the O( N ) vector model

    NASA Astrophysics Data System (ADS)

    Akers, Chris; Ben-Ami, Omer; Rosenhaus, Vladimir; Smolkin, Michael; Yankielowicz, Shimon

    2016-03-01

    We consider the large N interacting vector O( N ) model on a sphere in 4 - ɛ Euclidean dimensions. The Gaussian theory in the UV is taken to be either conformally or non-conformally coupled. The endpoint of the RG flow corresponds to a conformally coupled scalar field at the Wilson-Fisher fixed point. We take a spherical entangling surface in de Sitter space and compute the entanglement entropy everywhere along the RG trajectory. In 4 dimensions, a free non-conformal scalar has a universal area term scaling with the logarithm of the UV cutoff. In 4 - ɛ dimensions, such a term scales as 1 /ɛ. For a non-conformal scalar, a 1 /ɛ term is present both at the UV fixed point, and its vicinity. For flow between two conformal fixed points, 1 /ɛ terms are absent everywhere. Finally, we make contact with replica trick calculations. The conical singularity gives rise to boundary terms residing on the entangling surface, which are usually discarded. Consistency with our results requires they be kept. We argue that, in fact, this conclusion also follows from the work of Metlitski, Fuertes, and Sachdev, which demonstrated that such boundary terms will be generated through quantum corrections.

  2. Low Temperature Properties for Correlation Functions in Classical N-Vector Spin Models

    NASA Astrophysics Data System (ADS)

    Balaban, Tadeusz; O'Carroll, Michael

    We obtain convergent multi-scale expansions for the one-and two-point correlation functions of the low temperature lattice classical N- vector spin model in d>= 3 dimensions, N>= 2. The Gibbs factor is taken as where , , , are large and 0 < v<= 1. In the thermodynamic and limits, with h=e1, and Δ≡∂*∂, the expansion gives (spontaneous magnetization), , (Goldstone Bosons), , and , where , for some ρ > 0, and c0 is aprecisely determined constant.

  3. Third-harmonic exponent in three-dimensional N-vector models

    NASA Astrophysics Data System (ADS)

    de Prato, Martino; Pelissetto, Andrea; Vicari, Ettore

    2003-09-01

    We compute the crossover exponent associated with the spin-3 operator in three-dimensional O(N) models. A six-loop field-theoretical calculation in the fixed-dimension approach and a five-loop calculation in ɛ expansion give φ3=0.600(10) for the experimentally relevant case N=2 (XY model). The corresponding exponent β3=1.414(10) is compared with the experimental estimates obtained in materials undergoing a normal-incommensurate structural transition and in liquid crystals at the smectic-A hexatic-B phase transition, finding good agreement.

  4. Off-equilibrium scaling behaviors driven by time-dependent external fields in three-dimensional O (N ) vector models

    NASA Astrophysics Data System (ADS)

    Pelissetto, Andrea; Vicari, Ettore

    2016-03-01

    We consider the dynamical off-equilibrium behavior of the three-dimensional O (N ) vector model in the presence of a slowly varying time-dependent spatially uniform magnetic field H (t )=h (t )e , where e is an N -dimensional constant unit vector, h (t ) =t /ts , and ts is a time scale, at fixed temperature T ≤Tc , where Tc corresponds to the continuous order-disorder transition. The dynamic evolutions start from equilibrium configurations at hi<0 , correspondingly ti<0 , and end at time tf>0 with h (tf)>0 , or vice versa. We show that the magnetization displays an off-equilibrium scaling behavior close to the transition line H (t )=0 . It arises from the interplay among the time t , the time scale ts, and the finite size L . The scaling behavior can be parametrized in terms of the scaling variables tsκ/L and t /tsκt , where κ >0 and κt>0 are appropriate universal exponents, which differ at the critical point and for T model under a purely relaxational dynamics. They confirm the predicted off-equilibrium scaling behaviors at and below Tc. We also discuss hysteresis phenomena in round-trip protocols for the time dependence of the external field. We define a scaling function for the hysteresis loop area of the magnetization that can be used to quantify how far the system is from equilibrium.

  5. Double scaling limits and airy functions for {ital O}({ital N}) vector sigma models with elementary catastrophes or the catastrophe {ital X}{sub 9}

    SciTech Connect

    Ruehl, W.

    1996-05-01

    One and two vector sigma models are defined that possess catastrophes in their action. Each catastrophe defines a double scaling limit at {ital N}{r_arrow}{infinity}. Critical indices are calculated and the Airy functions are shown to satisfy RG equations. Copyright {copyright} 1996 Academic Press, Inc.

  6. Modeling collective cell motility

    NASA Astrophysics Data System (ADS)

    Rappel, Wouter-Jan

    Eukaryotic cells often move in groups, a critical aspect of many biological and medical processes including wound healing, morphogenesis and cancer metastasis. Modeling can provide useful insights into the fundamental mechanisms of collective cell motility. Constructing models that incorporate the physical properties of the cells, however, is challenging. Here, I discuss our efforts to build a comprehensive cell motility model that includes cell membrane properties, cell-substrate interactions, cell polarity, and cell-cell interaction. The model will be applied to a variety of systems, including motion on micropatterned substrates and the migration of border cells in Drosophila. This work was supported by NIH Grant No. P01 GM078586 and NSF Grant No. 1068869.

  7. Neurodynamical model of collective brain

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1992-01-01

    A dynamical system which mimics collective purposeful activities of a set of units of intelligence is introduced and discussed. A global control of the unit activities is replaced by the probabilistic correlations between them. These correlations are learned during a long term period of performing collective tasks, and are stored in the synaptic interconnections. The model is represented by a system of ordinary differential equations with terminal attractors and repellers, and does not contain any man-made digital devices.

  8. Modeling Charge Collection in Detector Arrays

    NASA Technical Reports Server (NTRS)

    Hardage, Donna (Technical Monitor); Pickel, J. C.

    2003-01-01

    A detector array charge collection model has been developed for use as an engineering tool to aid in the design of optical sensor missions for operation in the space radiation environment. This model is an enhancement of the prototype array charge collection model that was developed for the Next Generation Space Telescope (NGST) program. The primary enhancements were accounting for drift-assisted diffusion by Monte Carlo modeling techniques and implementing the modeling approaches in a windows-based code. The modeling is concerned with integrated charge collection within discrete pixels in the focal plane array (FPA), with high fidelity spatial resolution. It is applicable to all detector geometries including monolithc charge coupled devices (CCDs), Active Pixel Sensors (APS) and hybrid FPA geometries based on a detector array bump-bonded to a readout integrated circuit (ROIC).

  9. Locust Collective Motion and Its Modeling.

    PubMed

    Ariel, Gil; Ayali, Amir

    2015-12-01

    Over the past decade, technological advances in experimental and animal tracking techniques have motivated a renewed theoretical interest in animal collective motion and, in particular, locust swarming. This review offers a comprehensive biological background followed by comparative analysis of recent models of locust collective motion, in particular locust marching, their settings, and underlying assumptions. We describe a wide range of recent modeling and simulation approaches, from discrete agent-based models of self-propelled particles to continuous models of integro-differential equations, aimed at describing and analyzing the fascinating phenomenon of locust collective motion. These modeling efforts have a dual role: The first views locusts as a quintessential example of animal collective motion. As such, they aim at abstraction and coarse-graining, often utilizing the tools of statistical physics. The second, which originates from a more biological perspective, views locust swarming as a scientific problem of its own exceptional merit. The main goal should, thus, be the analysis and prediction of natural swarm dynamics. We discuss the properties of swarm dynamics using the tools of statistical physics, as well as the implications for laboratory experiments and natural swarms. Finally, we stress the importance of a combined-interdisciplinary, biological-theoretical effort in successfully confronting the challenges that locusts pose at both the theoretical and practical levels. PMID:26656851

  10. Locust Collective Motion and Its Modeling

    PubMed Central

    Ariel, Gil; Ayali, Amir

    2015-01-01

    Over the past decade, technological advances in experimental and animal tracking techniques have motivated a renewed theoretical interest in animal collective motion and, in particular, locust swarming. This review offers a comprehensive biological background followed by comparative analysis of recent models of locust collective motion, in particular locust marching, their settings, and underlying assumptions. We describe a wide range of recent modeling and simulation approaches, from discrete agent-based models of self-propelled particles to continuous models of integro-differential equations, aimed at describing and analyzing the fascinating phenomenon of locust collective motion. These modeling efforts have a dual role: The first views locusts as a quintessential example of animal collective motion. As such, they aim at abstraction and coarse-graining, often utilizing the tools of statistical physics. The second, which originates from a more biological perspective, views locust swarming as a scientific problem of its own exceptional merit. The main goal should, thus, be the analysis and prediction of natural swarm dynamics. We discuss the properties of swarm dynamics using the tools of statistical physics, as well as the implications for laboratory experiments and natural swarms. Finally, we stress the importance of a combined-interdisciplinary, biological-theoretical effort in successfully confronting the challenges that locusts pose at both the theoretical and practical levels. PMID:26656851

  11. The modelling cycle for collective animal behaviour

    PubMed Central

    Sumpter, David J. T.; Mann, Richard P.; Perna, Andrea

    2012-01-01

    Collective animal behaviour is the study of how interactions between individuals produce group level patterns, and why these interactions have evolved. This study has proved itself uniquely interdisciplinary, involving physicists, mathematicians, engineers as well as biologists. Almost all experimental work in this area is related directly or indirectly to mathematical models, with regular movement back and forth between models, experimental data and statistical fitting. In this paper, we describe how the modelling cycle works in the study of collective animal behaviour. We classify studies as addressing questions at different levels or linking different levels, i.e. as local, local to global, global to local or global. We also describe three distinct approaches—theory-driven, data-driven and model selection—to these questions. We show, with reference to our own research on species across different taxa, how we move between these different levels of description and how these various approaches can be applied to link levels together. PMID:23173077

  12. Developing New Models for Collection Development.

    ERIC Educational Resources Information Center

    Stoffle, Carla J.; Fore, Janet; Allen, Barbara

    1999-01-01

    Discusses the need to develop new models for collection development in academic libraries, based on experiences at the University of Arizona. Highlights include changes in the organizational chart; focusing on users' information goals and needs; integrative services; shared resources; interlibrary loans; digital technology; and funding. (LRW)

  13. The Ames Library: A Model for Collection Integration Collection

    ERIC Educational Resources Information Center

    Dickinson, Julia B.; George, Sarah E.

    2005-01-01

    Illinois Wesleyan University's Ames Library opened in January 2002. The vision for this library focused on creating a user-centered arrangement of information regardless of format. Much of the library's collection was integrated during the move to the new building; however, several discrete collections remain separate. This article will discuss…

  14. Modeling traction forces in collective cell migration

    NASA Astrophysics Data System (ADS)

    Zimmermann, Juliane; Basan, Markus; Hayes, Ryan L.; Rappel, Wouter-Jan; Levine, Herbert

    2015-03-01

    Collective cell migration is an important process in embryonic development, wound healing, and cancer metastasis. We have developed a particle-based simulation for collective cell migration that describes flow patterns and finger formation at the tissue edge observed in wound healing experiments. We can apply methods for calculating intercellular stress to our simulation model, and have thereby provided evidence for the validity of a stress reconstitution method from traction forces used in experiments. To accurately capture experimentally measured traction forces and stresses in the tissue, which are mostly tensile, we have to include intracellular acto-myosin contraction into our simulation. We can then reproduce the experimentally observed behavior of cells moving around a circular obstacle, and suggest underlying mechanisms for cell-cell alignment and generation of traction force patterns.

  15. On conviction's collective consequences: integrating moral conviction with the social identity model of collective action.

    PubMed

    van Zomeren, Martijn; Postmes, Tom; Spears, Russell

    2012-03-01

    This article examines whether and how moral convictions predict collective action to achieve social change. Because moral convictions - defined as strong and absolute stances on moral issues - tolerate no exceptions, any violation motivates individuals to actively change that situation. We propose that moral convictions have a special relationship with politicized identities and collective action because of the potentially strong normative fit between moral convictions and the action-oriented content of politicized identities. This effectively integrates moral conviction with the Social Identity Model of Collective Action (Van Zomeren, Postmes, & Spears, 2008), which predicts that, on the basis of a relevant social identity, group-based anger and efficacy predict collective action. Results from two studies indeed showed that moral convictions predicted collective action intentions (Study 1-2) and collective action (Study 2) through politicized identification, group-based anger, and group efficacy. We discuss theoretical and practical implications of our integrative model. PMID:22435846

  16. A computationally tractable version of the collective model

    NASA Astrophysics Data System (ADS)

    Rowe, D. J.

    2004-05-01

    A computationally tractable version of the Bohr-Mottelson collective model is presented which makes it possible to diagonalize realistic collective models and obtain convergent results in relatively small appropriately chosen subspaces of the collective model Hilbert space. Special features of the proposed model are that it makes use of the beta wave functions given analytically by the softened-beta version of the Wilets-Jean model, proposed by Elliott et al., and a simple algorithm for computing SO(5)⊃SO(3) spherical harmonics. The latter has much in common with the methods of Chacon, Moshinsky, and Sharp but is conceptually and computationally simpler. Results are presented for collective models ranging from the spherical vibrator to the Wilets-Jean and axially symmetric rotor-vibrator models.

  17. Modeling crowdsourcing as collective problem solving

    PubMed Central

    Guazzini, Andrea; Vilone, Daniele; Donati, Camillo; Nardi, Annalisa; Levnajić, Zoran

    2015-01-01

    Crowdsourcing is a process of accumulating the ideas, thoughts or information from many independent participants, with aim to find the best solution for a given challenge. Modern information technologies allow for massive number of subjects to be involved in a more or less spontaneous way. Still, the full potentials of crowdsourcing are yet to be reached. We introduce a modeling framework through which we study the effectiveness of crowdsourcing in relation to the level of collectivism in facing the problem. Our findings reveal an intricate relationship between the number of participants and the difficulty of the problem, indicating the optimal size of the crowdsourced group. We discuss our results in the context of modern utilization of crowdsourcing. PMID:26552943

  18. Modeling crowdsourcing as collective problem solving.

    PubMed

    Guazzini, Andrea; Vilone, Daniele; Donati, Camillo; Nardi, Annalisa; Levnajić, Zoran

    2015-01-01

    Crowdsourcing is a process of accumulating the ideas, thoughts or information from many independent participants, with aim to find the best solution for a given challenge. Modern information technologies allow for massive number of subjects to be involved in a more or less spontaneous way. Still, the full potentials of crowdsourcing are yet to be reached. We introduce a modeling framework through which we study the effectiveness of crowdsourcing in relation to the level of collectivism in facing the problem. Our findings reveal an intricate relationship between the number of participants and the difficulty of the problem, indicating the optimal size of the crowdsourced group. We discuss our results in the context of modern utilization of crowdsourcing. PMID:26552943

  19. Modeling crowdsourcing as collective problem solving

    NASA Astrophysics Data System (ADS)

    Guazzini, Andrea; Vilone, Daniele; Donati, Camillo; Nardi, Annalisa; Levnajić, Zoran

    2015-11-01

    Crowdsourcing is a process of accumulating the ideas, thoughts or information from many independent participants, with aim to find the best solution for a given challenge. Modern information technologies allow for massive number of subjects to be involved in a more or less spontaneous way. Still, the full potentials of crowdsourcing are yet to be reached. We introduce a modeling framework through which we study the effectiveness of crowdsourcing in relation to the level of collectivism in facing the problem. Our findings reveal an intricate relationship between the number of participants and the difficulty of the problem, indicating the optimal size of the crowdsourced group. We discuss our results in the context of modern utilization of crowdsourcing.

  20. Selecting Research Collections for Digitization: Applying the Harvard Model.

    ERIC Educational Resources Information Center

    Brancolini, Kristine R.

    2000-01-01

    Librarians at Harvard University have written the most comprehensive guide to selecting research collections for digitization. This article applies the Harvard Model to a digitization project at Indiana University in order to evaluate the appropriateness of the model for use at another institution and to adapt the model to local needs. (Contains 7…

  1. Injury Data Collection and Analysis - The NEISS Model

    ERIC Educational Resources Information Center

    Shumlansky, Joseph W.

    1974-01-01

    Describes the National Electronic Injury Surveillance System (NEISS) to demonstrate a model for injury data collection and analysis programs which includes an approach to describe the epidemiology of the product related injury problem. (MLB)

  2. Phase-field model for collective cell migration

    NASA Astrophysics Data System (ADS)

    Najem, Sara; Grant, Martin

    2016-05-01

    We construct a phase-field model for collective cell migration based on a Ginzburg-Landau free-energy formulation. We model adhesion, surface tension, repulsion, coattraction, and polarization, enabling us to follow the cells' morphologies and the effect of their membranes fluctuations on collective motion. We were able to measure the tissue surface tension as a function of the individual cell cortical tension and adhesion and identify a density threshold for cell-sheet formation.

  3. Modelling Rho GTPase biochemistry to predict collective cell migration

    NASA Astrophysics Data System (ADS)

    Merchant, Brian; Feng, James

    The collective migration of cells, due to individual cell polarization and intercellular contact inhibition of locomotion, features prominently in embryogenesis and metastatic cancers. Existing methods for modelling collectively migrating cells tend to rely either on highly abstracted agent-based models, or on continuum approximations of the group. Both of these frameworks represent intercellular interactions such as contact inhibition of locomotion as hard-coded rules defining model cells. In contrast, we present a vertex-dynamics framework which predicts polarization and contact inhibition of locomotion naturally from an underlying model of Rho GTPase biochemistry and cortical mechanics. We simulate the interaction between many such model cells, and study how modulating Rho GTPases affects migratory characteristics of the group, in the context of long-distance collective migration of neural crest cells during embryogenesis.

  4. Modeling and simulation of the SDC data collection chip

    SciTech Connect

    Hughes, E.; Haney, M.; Golin, E.; Jones, L.; Knapp, D.; Tharakan, G.; Downing, R. )

    1992-04-01

    This paper describes modeling and simulation of the Data Collection Chip (DCC) design for the Solenoidal Detector Collaboration (SDC). Models of the DCC written in Verilog and VHDL are described, and results are presented. The models have been simulated to study queue depth requirements and to compare control feedback alternatives. Insight into the management of models and simulation tools is given. Finally, techniques useful in the design process for data acquisition systems are discussed.

  5. Modeling and simulation of the SDC Data Collection Chip

    SciTech Connect

    Hughes, E.; Tharakan, G.; Downing, R.; Haney, M.; Golin, E.; Jones, L.; Knapp, D.; Thaler, J.

    1991-01-01

    This paper describes modeling and simulation of the Data Collection Chip (DCC) design for the Solenoidal Detector Collaboration (SDC). Models of the DCC written in Verilog and VHDL are described, and results are presented. The models have been simulated to study queue depth requirements and to compare control feedback alternatives. Insight into the management of models and simulation tools is given. Finally, techniques useful in the design process for data acquisition systems are discussed.

  6. Modeling and simulation of the SDC Data Collection Chip

    SciTech Connect

    Hughes, E.; Tharakan, G.; Downing, R.; Haney, M.; Golin, E.; Jones, L.; Knapp, D.; Thaler, J.

    1991-12-31

    This paper describes modeling and simulation of the Data Collection Chip (DCC) design for the Solenoidal Detector Collaboration (SDC). Models of the DCC written in Verilog and VHDL are described, and results are presented. The models have been simulated to study queue depth requirements and to compare control feedback alternatives. Insight into the management of models and simulation tools is given. Finally, techniques useful in the design process for data acquisition systems are discussed.

  7. Particle Swarm Based Collective Searching Model for Adaptive Environment

    SciTech Connect

    Cui, Xiaohui; Patton, Robert M; Potok, Thomas E; Treadwell, Jim N

    2007-01-01

    This report presents a pilot study of an integration of particle swarm algorithm, social knowledge adaptation and multi-agent approaches for modeling the collective search behavior of self-organized groups in an adaptive environment. The objective of this research is to apply the particle swarm metaphor as a model of social group adaptation for the dynamic environment and to provide insight and understanding of social group knowledge discovering and strategic searching. A new adaptive environment model, which dynamically reacts to the group collective searching behaviors, is proposed in this research. The simulations in the research indicate that effective communication between groups is not the necessary requirement for whole self-organized groups to achieve the efficient collective searching behavior in the adaptive environment.

  8. Particle Swarm Based Collective Searching Model for Adaptive Environment

    SciTech Connect

    Cui, Xiaohui; Patton, Robert M; Potok, Thomas E; Treadwell, Jim N

    2008-01-01

    This report presents a pilot study of an integration of particle swarm algorithm, social knowledge adaptation and multi-agent approaches for modeling the collective search behavior of self-organized groups in an adaptive environment. The objective of this research is to apply the particle swarm metaphor as a model of social group adaptation for the dynamic environment and to provide insight and understanding of social group knowledge discovering and strategic searching. A new adaptive environment model, which dynamically reacts to the group collective searching behaviors, is proposed in this research. The simulations in the research indicate that effective communication between groups is not the necessary requirement for whole self-organized groups to achieve the efficient collective searching behavior in the adaptive environment.

  9. Satellite image collection modeling for large area hazard emergency response

    NASA Astrophysics Data System (ADS)

    Liu, Shufan; Hodgson, Michael E.

    2016-08-01

    Timely collection of critical hazard information is the key to intelligent and effective hazard emergency response decisions. Satellite remote sensing imagery provides an effective way to collect critical information. Natural hazards, however, often have large impact areas - larger than a single satellite scene. Additionally, the hazard impact area may be discontinuous, particularly in flooding or tornado hazard events. In this paper, a spatial optimization model is proposed to solve the large area satellite image acquisition planning problem in the context of hazard emergency response. In the model, a large hazard impact area is represented as multiple polygons and image collection priorities for different portion of impact area are addressed. The optimization problem is solved with an exact algorithm. Application results demonstrate that the proposed method can address the satellite image acquisition planning problem. A spatial decision support system supporting the optimization model was developed. Several examples of image acquisition problems are used to demonstrate the complexity of the problem and derive optimized solutions.

  10. A simple generative model of collective online behavior.

    PubMed

    Gleeson, James P; Cellai, Davide; Onnela, Jukka-Pekka; Porter, Mason A; Reed-Tsochas, Felix

    2014-07-22

    Human activities increasingly take place in online environments, providing novel opportunities for relating individual behaviors to population-level outcomes. In this paper, we introduce a simple generative model for the collective behavior of millions of social networking site users who are deciding between different software applications. Our model incorporates two distinct mechanisms: one is associated with recent decisions of users, and the other reflects the cumulative popularity of each application. Importantly, although various combinations of the two mechanisms yield long-time behavior that is consistent with data, the only models that reproduce the observed temporal dynamics are those that strongly emphasize the recent popularity of applications over their cumulative popularity. This demonstrates--even when using purely observational data without experimental design--that temporal data-driven modeling can effectively distinguish between competing microscopic mechanisms, allowing us to uncover previously unidentified aspects of collective online behavior. PMID:25002470

  11. A simple generative model of collective online behavior

    PubMed Central

    Gleeson, James P.; Cellai, Davide; Onnela, Jukka-Pekka; Porter, Mason A.; Reed-Tsochas, Felix

    2014-01-01

    Human activities increasingly take place in online environments, providing novel opportunities for relating individual behaviors to population-level outcomes. In this paper, we introduce a simple generative model for the collective behavior of millions of social networking site users who are deciding between different software applications. Our model incorporates two distinct mechanisms: one is associated with recent decisions of users, and the other reflects the cumulative popularity of each application. Importantly, although various combinations of the two mechanisms yield long-time behavior that is consistent with data, the only models that reproduce the observed temporal dynamics are those that strongly emphasize the recent popularity of applications over their cumulative popularity. This demonstrates—even when using purely observational data without experimental design—that temporal data-driven modeling can effectively distinguish between competing microscopic mechanisms, allowing us to uncover previously unidentified aspects of collective online behavior. PMID:25002470

  12. The proton-neutron symplectic model of nuclear collective motions

    NASA Astrophysics Data System (ADS)

    Ganev, H. G.

    2016-06-01

    The proton-neutron symplectic model of nuclear collective motion is presented. It is shown that it appears as a natural multi-major-shell extension of the generalized proton- neutron SU(3) scheme which includes rotations with intrinsic vortex as well as monopole, quadrupole and dipole giant resonance vibrational degrees of freedom.

  13. Building and Sustaining Digital Collections: Models for Libraries and Museums.

    ERIC Educational Resources Information Center

    Council on Library and Information Resources, Washington, DC.

    In February 2001, the Council on Library and Information Resources (CLIR) and the National Initiative for a Networked Cultural Heritage (NINCH) convened a meeting to discuss how museums and libraries are building digital collections and what business models are available to sustain them. A group of museum and library senior executives met with…

  14. Emergent collective decision-making: Control, model and behavior

    NASA Astrophysics Data System (ADS)

    Shen, Tian

    In this dissertation we study emergent collective decision-making in social groups with time-varying interactions and heterogeneously informed individuals. First we analyze a nonlinear dynamical systems model motivated by animal collective motion with heterogeneously informed subpopulations, to examine the role of uninformed individuals. We find through formal analysis that adding uninformed individuals in a group increases the likelihood of a collective decision. Secondly, we propose a model for human shared decision-making with continuous-time feedback and where individuals have little information about the true preferences of other group members. We study model equilibria using bifurcation analysis to understand how the model predicts decisions based on the critical threshold parameters that represent an individual's tradeoff between social and environmental influences. Thirdly, we analyze continuous-time data of pairs of human subjects performing an experimental shared tracking task using our second proposed model in order to understand transient behavior and the decision-making process. We fit the model to data and show that it reproduces a wide range of human behaviors surprisingly well, suggesting that the model may have captured the mechanisms of observed behaviors. Finally, we study human behavior from a game-theoretic perspective by modeling the aforementioned tracking task as a repeated game with incomplete information. We show that the majority of the players are able to converge to playing Nash equilibrium strategies. We then suggest with simulations that the mean field evolution of strategies in the population resemble replicator dynamics, indicating that the individual strategies may be myopic. Decisions form the basis of control and problems involving deciding collectively between alternatives are ubiquitous in nature and in engineering. Understanding how multi-agent systems make decisions among alternatives also provides insight for designing

  15. Forecasting rain events - Meteorological models or collective intelligence?

    NASA Astrophysics Data System (ADS)

    Arazy, Ofer; Halfon, Noam; Malkinson, Dan

    2015-04-01

    Collective intelligence is shared (or group) intelligence that emerges from the collective efforts of many individuals. Collective intelligence is the aggregate of individual contributions: from simple collective decision making to more sophisticated aggregations such as in crowdsourcing and peer-production systems. In particular, collective intelligence could be used in making predictions about future events, for example by using prediction markets to forecast election results, stock prices, or the outcomes of sport events. To date, there is little research regarding the use of collective intelligence for prediction of weather forecasting. The objective of this study is to investigate the extent to which collective intelligence could be utilized to accurately predict weather events, and in particular rainfall. Our analyses employ metrics of group intelligence, as well as compare the accuracy of groups' predictions against the predictions of the standard model used by the National Meteorological Services. We report on preliminary results from a study conducted over the 2013-2014 and 2014-2015 winters. We have built a web site that allows people to make predictions on precipitation levels on certain locations. During each competition participants were allowed to enter their precipitation forecasts (i.e. 'bets') at three locations and these locations changed between competitions. A precipitation competition was defined as a 48-96 hour period (depending on the expected weather conditions), bets were open 24-48 hours prior to the competition, and during betting period participants were allowed to change their bets with no limitation. In order to explore the effect of transparency, betting mechanisms varied across study's sites: full transparency (participants able to see each other's bets); partial transparency (participants see the group's average bet); and no transparency (no information of others' bets is made available). Several interesting findings emerged from

  16. Bootstrapping O( N ) vector models with four supercharges in 3 ≤ d ≤ 4

    NASA Astrophysics Data System (ADS)

    Chester, Shai M.; Iliesiu, Luca V.; Pufu, Silviu S.; Yacoby, Ran

    2016-05-01

    We analyze the conformal bootstrap constraints in theories with four super-charges and a global O( N ) × U(1) flavor symmetry in 3 ≤ d ≤ 4 dimensions. In particular, we consider the 4-point function of O( N )-fundamental chiral operators Z i that have no chiral primary in the O( N )-singlet sector of their OPE. We find features in our numerical bounds that nearly coincide with the theory of N + 1 chiral super-fields with superpotential W = X∑ i = 1 N Z i 2 as well as general bounds on SCFTs where ∑ i = 1 N Z i 2 vanishes in the chiral ring.

  17. On effective temperature in network models of collective behavior

    NASA Astrophysics Data System (ADS)

    Porfiri, Maurizio; Ariel, Gil

    2016-04-01

    Collective behavior of self-propelled units is studied analytically within the Vectorial Network Model (VNM), a mean-field approximation of the well-known Vicsek model. We propose a dynamical systems framework to study the stochastic dynamics of the VNM in the presence of general additive noise. We establish that a single parameter, which is a linear function of the circular mean of the noise, controls the macroscopic phase of the system—ordered or disordered. By establishing a fluctuation-dissipation relation, we posit that this parameter can be regarded as an effective temperature of collective behavior. The exact critical temperature is obtained analytically for systems with small connectivity, equivalent to low-density ensembles of self-propelled units. Numerical simulations are conducted to demonstrate the applicability of this new notion of effective temperature to the Vicsek model. The identification of an effective temperature of collective behavior is an important step toward understanding order-disorder phase transitions, informing consistent coarse-graining techniques and explaining the physics underlying the emergence of collective phenomena.

  18. On effective temperature in network models of collective behavior.

    PubMed

    Porfiri, Maurizio; Ariel, Gil

    2016-04-01

    Collective behavior of self-propelled units is studied analytically within the Vectorial Network Model (VNM), a mean-field approximation of the well-known Vicsek model. We propose a dynamical systems framework to study the stochastic dynamics of the VNM in the presence of general additive noise. We establish that a single parameter, which is a linear function of the circular mean of the noise, controls the macroscopic phase of the system-ordered or disordered. By establishing a fluctuation-dissipation relation, we posit that this parameter can be regarded as an effective temperature of collective behavior. The exact critical temperature is obtained analytically for systems with small connectivity, equivalent to low-density ensembles of self-propelled units. Numerical simulations are conducted to demonstrate the applicability of this new notion of effective temperature to the Vicsek model. The identification of an effective temperature of collective behavior is an important step toward understanding order-disorder phase transitions, informing consistent coarse-graining techniques and explaining the physics underlying the emergence of collective phenomena. PMID:27131488

  19. A Microscopic Quantal Model for Nuclear Collective Rotation

    SciTech Connect

    Gulshani, P.

    2007-10-26

    A microscopic, quantal model to describe nuclear collective rotation in two dimensions is derived from the many-nucleon Schrodinger equation. The Schrodinger equation is transformed to a body-fixed frame to decompose the Hamiltonian into a sum of intrinsic and rotational components plus a Coriolis-centrifugal coupling term. This Hamiltonian (H) is expressed in terms of space-fixed-frame particle coordinates and momenta by using commutator of H with a rotation angle. A unified-rotational-model type wavefunction is used to obtain an intrinsic Schrodinger equation in terms of angular momentum quantum number and two-body operators. A Hartree-Fock mean-field representation of this equation is then obtained and, by means of a unitary transformation, is reduced to a form resembling that of the conventional semi-classical cranking model when exchange terms and intrinsic spurious collective excitation are ignored.

  20. Adaptive network models of collective decision making in swarming systems.

    PubMed

    Chen, Li; Huepe, Cristián; Gross, Thilo

    2016-08-01

    We consider a class of adaptive network models where links can only be created or deleted between nodes in different states. These models provide an approximate description of a set of systems where nodes represent agents moving in physical or abstract space, the state of each node represents the agent's heading direction, and links indicate mutual awareness. We show analytically that the adaptive network description captures a phase transition to collective motion in some swarming systems, such as the Vicsek model, and that the properties of this transition are determined by the number of states (discrete heading directions) that can be accessed by each agent. PMID:27627342

  1. Nonlinear model predictive control based on collective neurodynamic optimization.

    PubMed

    Yan, Zheng; Wang, Jun

    2015-04-01

    In general, nonlinear model predictive control (NMPC) entails solving a sequential global optimization problem with a nonconvex cost function or constraints. This paper presents a novel collective neurodynamic optimization approach to NMPC without linearization. Utilizing a group of recurrent neural networks (RNNs), the proposed collective neurodynamic optimization approach searches for optimal solutions to global optimization problems by emulating brainstorming. Each RNN is guaranteed to converge to a candidate solution by performing constrained local search. By exchanging information and iteratively improving the starting and restarting points of each RNN using the information of local and global best known solutions in a framework of particle swarm optimization, the group of RNNs is able to reach global optimal solutions to global optimization problems. The essence of the proposed collective neurodynamic optimization approach lies in the integration of capabilities of global search and precise local search. The simulation results of many cases are discussed to substantiate the effectiveness and the characteristics of the proposed approach. PMID:25608315

  2. Modeling closure of circular wounds through coordinated collective motion.

    PubMed

    Li, David S; Zimmermann, Juliane; Levine, Herbert

    2016-02-01

    Wound healing enables tissues to restore their original states, and is achieved through collective cell migration into the wound space, contraction of the wound edge via an actomyosin filament 'purse-string,' as well as cell division. Recently, experimental techniques have been developed to create wounds with various regular morphologies in epithelial monolayers, and these experiments of circular closed-contour wounds support coordinated lamellipodial cell crawling as the predominant driver of gap closure. Through utilizing a particle-based mechanical tissue simulation, exhibiting long-range coordination of cell motility, we computationally model these closed-contour experiments with a high level of agreement between experimentally observed and simulated wound closure dynamics and tissue velocity profiles. We also determine the sensitivity of wound closure time in the model to changes in cell motility force and division rate. Our simulation results confirm that circular wounds can close due to collective cell migration without the necessity for a purse-string mechanism or for cell division, and show that the alignment mechanism of cellular motility force with velocity, leading to collective motion in the model, may speed up wound closure. PMID:26871883

  3. Waste collection multi objective model with real time traceability data.

    PubMed

    Faccio, Maurizio; Persona, Alessandro; Zanin, Giorgia

    2011-12-01

    Waste collection is a highly visible municipal service that involves large expenditures and difficult operational problems, plus it is expensive to operate in terms of investment costs (i.e. vehicles fleet), operational costs (i.e. fuel, maintenances) and environmental costs (i.e. emissions, noise and traffic congestions). Modern traceability devices, like volumetric sensors, identification RFID (Radio Frequency Identification) systems, GPRS (General Packet Radio Service) and GPS (Global Positioning System) technology, permit to obtain data in real time, which is fundamental to implement an efficient and innovative waste collection routing model. The basic idea is that knowing the real time data of each vehicle and the real time replenishment level at each bin makes it possible to decide, in function of the waste generation pattern, what bin should be emptied and what should not, optimizing different aspects like the total covered distance, the necessary number of vehicles and the environmental impact. This paper describes a framework about the traceability technology available in the optimization of solid waste collection, and introduces an innovative vehicle routing model integrated with the real time traceability data, starting the application in an Italian city of about 100,000 inhabitants. The model is tested and validated using simulation and an economical feasibility study is reported at the end of the paper. PMID:21821406

  4. Modeling closure of circular wounds through coordinated collective motion

    NASA Astrophysics Data System (ADS)

    Li, David S.; Zimmermann, Juliane; Levine, Herbert

    2016-02-01

    Wound healing enables tissues to restore their original states, and is achieved through collective cell migration into the wound space, contraction of the wound edge via an actomyosin filament ‘purse-string,’ as well as cell division. Recently, experimental techniques have been developed to create wounds with various regular morphologies in epithelial monolayers, and these experiments of circular closed-contour wounds support coordinated lamellipodial cell crawling as the predominant driver of gap closure. Through utilizing a particle-based mechanical tissue simulation, exhibiting long-range coordination of cell motility, we computationally model these closed-contour experiments with a high level of agreement between experimentally observed and simulated wound closure dynamics and tissue velocity profiles. We also determine the sensitivity of wound closure time in the model to changes in cell motility force and division rate. Our simulation results confirm that circular wounds can close due to collective cell migration without the necessity for a purse-string mechanism or for cell division, and show that the alignment mechanism of cellular motility force with velocity, leading to collective motion in the model, may speed up wound closure.

  5. AdS{sub 4}/CFT{sub 3} construction from collective fields

    SciTech Connect

    Mello Koch, Robert de; Rodrigues, Joao P.; Jevicki, Antal; Jin, Kewang

    2011-01-15

    We pursue the construction of higher-spin theory in AdS{sub 4} from CFT{sub 3} of the O(N) vector model in terms of canonical collective fields. In null-plane quantization an exact map is established between the two spaces. The coordinates of the AdS{sub 4} space-time are generated from the collective coordinates of the bi-local field. This, in the light-cone gauge, provides an exact one-to-one reconstruction of bulk AdS{sub 4} space-time and higher-spin fields.

  6. Modeling species-abundance relationships in multi-species collections

    USGS Publications Warehouse

    Peng, S.; Yin, Z.; Ren, H.; Guo, Q.

    2003-01-01

    Species-abundance relationship is one of the most fundamental aspects of community ecology. Since Motomura first developed the geometric series model to describe the feature of community structure, ecologists have developed many other models to fit the species-abundance data in communities. These models can be classified into empirical and theoretical ones, including (1) statistical models, i.e., negative binomial distribution (and its extension), log-series distribution (and its extension), geometric distribution, lognormal distribution, Poisson-lognormal distribution, (2) niche models, i.e., geometric series, broken stick, overlapping niche, particulate niche, random assortment, dominance pre-emption, dominance decay, random fraction, weighted random fraction, composite niche, Zipf or Zipf-Mandelbrot model, and (3) dynamic models describing community dynamics and restrictive function of environment on community. These models have different characteristics and fit species-abundance data in various communities or collections. Among them, log-series distribution, lognormal distribution, geometric series, and broken stick model have been most widely used.

  7. Collective opinion formation model under Bayesian updating and confirmation bias.

    PubMed

    Nishi, Ryosuke; Masuda, Naoki

    2013-06-01

    We propose a collective opinion formation model with a so-called confirmation bias. The confirmation bias is a psychological effect with which, in the context of opinion formation, an individual in favor of an opinion is prone to misperceive new incoming information as supporting the current belief of the individual. Our model modifies a Bayesian decision-making model for single individuals [M. Rabin and J. L. Schrag, Q. J. Econ. 114, 37 (1999)] for the case of a well-mixed population of interacting individuals in the absence of the external input. We numerically simulate the model to show that all the agents eventually agree on one of the two opinions only when the confirmation bias is weak. Otherwise, the stochastic population dynamics ends up creating a disagreement configuration (also called polarization), particularly for large system sizes. A strong confirmation bias allows various final disagreement configurations with different fractions of the individuals in favor of the opposite opinions. PMID:23848643

  8. A model for collective dynamics in ant raids.

    PubMed

    Ryan, Shawn D

    2016-05-01

    Ant raiding, the process of identifying and returning food to the nest or bivouac, is a fascinating example of collective motion in nature. During such raids ants lay pheromones to form trails for others to find a food source. In this work a coupled PDE/ODE model is introduced to study ant dynamics and pheromone concentration. The key idea is the introduction of two forms of ant dynamics: foraging and returning, each governed by different environmental and social cues. The model accounts for all aspects of the raiding cycle including local collisional interactions, the laying of pheromone along a trail, and the transition from one class of ants to another. Through analysis of an order parameter measuring the orientational order in the system, the model shows self-organization into a collective state consisting of lanes of ants moving in opposite directions as well as the transition back to the individual state once the food source is depleted matching prior experimental results. This indicates that in the absence of direct communication ants naturally form an efficient method for transporting food to the nest/bivouac. The model exhibits a continuous kinetic phase transition in the order parameter as a function of certain system parameters. The associated critical exponents are found, shedding light on the behavior of the system near the transition. PMID:26304617

  9. Collecting, Visualising, Communicating and Modelling Geographic Data for the Sciences

    NASA Astrophysics Data System (ADS)

    Crooks, A.; Hudson-Smith, A.; Milton, R.; Smith, D.; Batty, M.; Neuhaus, F.

    2009-12-01

    New web technologies and task specific software packages and services are fundamentally changing the way we share, collect, visualise, communicate and distribute geographic information. Coupled with these new technologies is the emergence of rich fine scale and extensive geographical datasets of the built environment. Such technologies and data are providing opportunities for both the social and physical sciences that were unimaginable ten years ago. Within this paper we discus such change from our own experiences at the Centre of Advanced Spatial Analysis. Specifically, how it is now possible to harness the crowd to collect peoples’ opinions about topical events such as the current financial crisis, in real time and map the results, through the use of our GMapCreator software and the MapTube website. Furthermore, such tools allow for widespread dissemination and visualisation of geographic data to whoever has an internet connection. We will explore how one can use new datasets to visualise the city using our Virtual London model as an example. Within the model individual buildings are tagged with multiple attributes providing a lens to explore the urban structure offering a plethora of research applications. We then turn to how one can visualise and communicate such data through low cost software and virtual worlds such as Crysis and Second Life with a look into their potential for modelling and finally how we disseminated much of this information through weblogs (blogs) such as Digital Urban, GIS and Agent-based modelling and Urban Tick.

  10. Minimal model for collective kinetochore-microtubule dynamics.

    PubMed

    Banigan, Edward J; Chiou, Kevin K; Ballister, Edward R; Mayo, Alyssa M; Lampson, Michael A; Liu, Andrea J

    2015-10-13

    Chromosome segregation during cell division depends on interactions of kinetochores with dynamic microtubules (MTs). In many eukaryotes, each kinetochore binds multiple MTs, but the collective behavior of these coupled MTs is not well understood. We present a minimal model for collective kinetochore-MT dynamics, based on in vitro measurements of individual MTs and their dependence on force and kinetochore phosphorylation by Aurora B kinase. For a system of multiple MTs connected to the same kinetochore, the force-velocity relation has a bistable regime with two possible steady-state velocities: rapid shortening or slow growth. Bistability, combined with the difference between the growing and shrinking speeds, leads to center-of-mass and breathing oscillations in bioriented sister kinetochore pairs. Kinetochore phosphorylation shifts the bistable region to higher tensions, so that only the rapidly shortening state is stable at low tension. Thus, phosphorylation leads to error correction for kinetochores that are not under tension. We challenged the model with new experiments, using chemically induced dimerization to enhance Aurora B activity at metaphase kinetochores. The model suggests that the experimentally observed disordering of the metaphase plate occurs because phosphorylation increases kinetochore speeds by biasing MTs to shrink. Our minimal model qualitatively captures certain characteristic features of kinetochore dynamics, illustrates how biochemical signals such as phosphorylation may regulate the dynamics, and provides a theoretical framework for understanding other factors that control the dynamics in vivo. PMID:26417109

  11. A New Model for Building Digital Science Education Collections

    NASA Astrophysics Data System (ADS)

    Niepold, F.; McCaffrey, M.; Morrill, C.; Ganse, J.; Weston, T.

    2005-12-01

    The Polar Regions play an integral role in how our Earth system operates. However, the Polar Regions are marginally studied in the K-12 classroom in the United States. The International Polar Year's (IPY) coordinated campaign of polar observations, research, and analysis that will be multidisciplinary in scope and international in participation offers a powerful opportunity for K-12 classroom. The IPY's scientific objective to better understand the key roles of the Polar Regions in global processes will allow students a window into the poles and this unique regions role in the Earth system. IPY will produce careful, useful scientific information that will advance our understanding of the Polar Regions and their connections to the rest of the globe. The IPY is an opportunity to inspire the next generation of very young Earth system scientists. The IPY's draft education & outreach position paper asks a key question that must guide future educational projects; "Why is the polar regions and polar research important to all people on earth?" In efforts to coordinate educational activities and collaborate with international projects, United States national agencies, and other educational initiatives, it is the purpose of this session to explore potential partnerships, while primarily recommending a model for educational product development and review. During such a large international science endeavor, numerous educational activities and opportunities are developed, but these educational programs can suffer from too many unconnected options being available to teachers and students. Additionally, activities often are incompatible with each other making classroom implementation unnecessarily complex and prohibitively time consuming for teachers. A newly develop educational activity collection technique developed for DLESE offers an effective model for IPY product gap analysis and development. The Climate Change Collection developed as a pilot project for the Digital Library

  12. Modeling local chemistry in the presence of collective phenomena.

    SciTech Connect

    Chandross, Michael Evan; Modine, Normand Arthur

    2005-01-01

    Confinement within the nanoscale pores of a zeolite strongly modifies the behavior of small molecules. Typical of many such interesting and important problems, realistic modeling of this phenomena requires simultaneously capturing the detailed behavior of chemical bonds and the possibility of collective dynamics occurring in a complex unit cell (672 atoms in the case of Zeolite-4A). Classical simulations alone cannot reliably model the breaking and formation of chemical bonds, while quantum methods alone are incapable of treating the extended length and time scales characteristic of complex dynamics. We have developed a robust and efficient model in which a small region treated with the Kohn-Sham density functional theory is embedded within a larger system represented with classical potentials. This model has been applied in concert with first-principles electronic structure calculations and classical molecular dynamics and Monte Carlo simulations to study the behavior of water, ammonia, the hydroxide ion, and the ammonium ion in Zeolite-4a. Understanding this behavior is important to the predictive modeling of the aging of Zeolite-based desiccants. In particular, we have studied the absorption of these molecules, interactions between water and the ammonium ion, and reactions between the hydroxide ion and the zeolite cage. We have shown that interactions with the extended Zeolite cage strongly modifies these local chemical phenomena, and thereby we have proven out hypothesis that capturing both local chemistry and collective phenomena is essential to realistic modeling of this system. Based on our results, we have been able to identify two possible mechanisms for the aging of Zeolite-based desiccants.

  13. Measuring and modeling behavioral decision dynamics in collective evacuation.

    PubMed

    Carlson, Jean M; Alderson, David L; Stromberg, Sean P; Bassett, Danielle S; Craparo, Emily M; Guiterrez-Villarreal, Francisco; Otani, Thomas

    2014-01-01

    Identifying and quantifying factors influencing human decision making remains an outstanding challenge, impacting the performance and predictability of social and technological systems. In many cases, system failures are traced to human factors including congestion, overload, miscommunication, and delays. Here we report results of a behavioral network science experiment, targeting decision making in a natural disaster. In a controlled laboratory setting, our results quantify several key factors influencing individual evacuation decision making in a controlled laboratory setting. The experiment includes tensions between broadcast and peer-to-peer information, and contrasts the effects of temporal urgency associated with the imminence of the disaster and the effects of limited shelter capacity for evacuees. Based on empirical measurements of the cumulative rate of evacuations as a function of the instantaneous disaster likelihood, we develop a quantitative model for decision making that captures remarkably well the main features of observed collective behavior across many different scenarios. Moreover, this model captures the sensitivity of individual- and population-level decision behaviors to external pressures, and systematic deviations from the model provide meaningful estimates of variability in the collective response. Identification of robust methods for quantifying human decisions in the face of risk has implications for policy in disasters and other threat scenarios, specifically the development and testing of robust strategies for training and control of evacuations that account for human behavior and network topologies. PMID:24520331

  14. User-friendly software for modeling collective spin wave excitations

    NASA Astrophysics Data System (ADS)

    Hahn, Steven; Peterson, Peter; Fishman, Randy; Ehlers, Georg

    There exists a great need for user-friendly, integrated software that assists in the scientific analysis of collective spin wave excitations measured with inelastic neutron scattering. SpinWaveGenie is a C + + software library that simplifies the modeling of collective spin wave excitations, allowing scientists to analyze neutron scattering data with sophisticated models fast and efficiently. Furthermore, one can calculate the four-dimensional scattering function S(Q,E) to directly compare and fit calculations to experimental measurements. Its generality has been both enhanced and verified through successful modeling of a wide array of magnetic materials. Recently, we have spent considerable effort transforming SpinWaveGenie from an early prototype to a high quality free open source software package for the scientific community. S.E.H. acknowledges support by the Laboratory's Director's fund, ORNL. Work was sponsored by the Division of Scientific User Facilities, Office of Basic Energy Sciences, US Department of Energy, under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.

  15. Collective Diffusion Model for Ion Conduction through Microscopic Channels

    PubMed Central

    Liu, Yingting; Zhu, Fangqiang

    2013-01-01

    Ion conduction through microscopic channels is of central importance in both biology and nanotechnology. To better understand the current-voltage (I-V) dependence of ion channels, here we describe and prove a collective diffusion model that quantitatively relates the spontaneous ion permeation at equilibrium to the stationary ionic fluxes driven by small voltages. The model makes it possible to determine the channel conductance in the linear I-V range from equilibrium simulations without the application of a voltage. To validate the theory, we perform molecular-dynamics simulations on two channels—a conical-shaped nanopore and the transmembrane pore of an α-hemolysin—under both equilibrium and nonequilibrium conditions. The simulations reveal substantial couplings between the motions of cations and anions, which are effectively captured by the collective coordinate in the model. Although the two channels exhibit very different linear ranges in the I-V curves, in both cases the channel conductance at small voltages is in reasonable agreement with the prediction from the equilibrium simulation. The simulations also suggest that channel charges, rather than geometric asymmetry, play a more prominent role in current rectification. PMID:23442858

  16. Measuring and Modeling Behavioral Decision Dynamics in Collective Evacuation

    PubMed Central

    Carlson, Jean M.; Alderson, David L.; Stromberg, Sean P.; Bassett, Danielle S.; Craparo, Emily M.; Guiterrez-Villarreal, Francisco; Otani, Thomas

    2014-01-01

    Identifying and quantifying factors influencing human decision making remains an outstanding challenge, impacting the performance and predictability of social and technological systems. In many cases, system failures are traced to human factors including congestion, overload, miscommunication, and delays. Here we report results of a behavioral network science experiment, targeting decision making in a natural disaster. In a controlled laboratory setting, our results quantify several key factors influencing individual evacuation decision making in a controlled laboratory setting. The experiment includes tensions between broadcast and peer-to-peer information, and contrasts the effects of temporal urgency associated with the imminence of the disaster and the effects of limited shelter capacity for evacuees. Based on empirical measurements of the cumulative rate of evacuations as a function of the instantaneous disaster likelihood, we develop a quantitative model for decision making that captures remarkably well the main features of observed collective behavior across many different scenarios. Moreover, this model captures the sensitivity of individual- and population-level decision behaviors to external pressures, and systematic deviations from the model provide meaningful estimates of variability in the collective response. Identification of robust methods for quantifying human decisions in the face of risk has implications for policy in disasters and other threat scenarios, specifically the development and testing of robust strategies for training and control of evacuations that account for human behavior and network topologies. PMID:24520331

  17. Modelling Influence and Opinion Evolution in Online Collective Behaviour

    PubMed Central

    Gend, Pascal; Rentfrow, Peter J.; Hendrickx, Julien M.; Blondel, Vincent D.

    2016-01-01

    Opinion evolution and judgment revision are mediated through social influence. Based on a large crowdsourced in vitro experiment (n = 861), it is shown how a consensus model can be used to predict opinion evolution in online collective behaviour. It is the first time the predictive power of a quantitative model of opinion dynamics is tested against a real dataset. Unlike previous research on the topic, the model was validated on data which did not serve to calibrate it. This avoids to favor more complex models over more simple ones and prevents overfitting. The model is parametrized by the influenceability of each individual, a factor representing to what extent individuals incorporate external judgments. The prediction accuracy depends on prior knowledge on the participants’ past behaviour. Several situations reflecting data availability are compared. When the data is scarce, the data from previous participants is used to predict how a new participant will behave. Judgment revision includes unpredictable variations which limit the potential for prediction. A first measure of unpredictability is proposed. The measure is based on a specific control experiment. More than two thirds of the prediction errors are found to occur due to unpredictability of the human judgment revision process rather than to model imperfection. PMID:27336834

  18. Collective field theory of a singular supersymmetric matrix model

    SciTech Connect

    de Mello Koch, R.; Rodrigues, J.P.

    1995-05-15

    The supersymmetric collective field theory with the potential {ital v}{prime}({ital x})={omega}{ital x}{minus}{eta}/{ital x} is studied. Consistency with supersymmetry enforces a two band solution. A supersymmetric classical configuration is found, and interpreted in terms of the density of zeroes of certain Laguerre polynomials. The spectrum of the model is then studied and is seen to correspond to a massless scalar and a Majorana fermion. The {ital x} space eigenfunctions are constructed and expressed in terms of Chebyshev polynomials. Higher order interactions are also discussed.

  19. Yang-Mills generalization of the geometrical collective model

    NASA Astrophysics Data System (ADS)

    Rosensteel, George; Sparks, Nick

    2015-04-01

    The geometrical or Bohr-Mottelson model is generalized and recast as a Yang-Mills theory. The gauge symmetry determines conservation of Kelvin circulation. The circulation commutes with the Hamiltonian when it is the sum of the kinetic energy and a potential that depends only on deformation. The conventional Bohr-Mottelson model is the special case of circulation zero, and wave functions are complex-valued. In the generalization, any quantized value of the circulation is allowed, and the wave functions are vector-valued. The Yang-Mills formulation introduces a new coupling between the geometrical and intrinsic degrees of freedom. The coupling appears in the covariant derivative term of the collective kinetic energy. This kind of coupling is sometimes called ``magnetic'' because of the analogy with electrodynamics.

  20. Simple model for multiple-choice collective decision making.

    PubMed

    Lee, Ching Hua; Lucas, Andrew

    2014-11-01

    We describe a simple model of heterogeneous, interacting agents making decisions between n≥2 discrete choices. For a special class of interactions, our model is the mean field description of random field Potts-like models and is effectively solved by finding the extrema of the average energy E per agent. In these cases, by studying the propagation of decision changes via avalanches, we argue that macroscopic dynamics is well captured by a gradient flow along E. We focus on the permutation symmetric case, where all n choices are (on average) the same, and spontaneous symmetry breaking (SSB) arises purely from cooperative social interactions. As examples, we show that bimodal heterogeneity naturally provides a mechanism for the spontaneous formation of hierarchies between decisions and that SSB is a preferred instability to discontinuous phase transitions between two symmetric points. Beyond the mean field limit, exponentially many stable equilibria emerge when we place this model on a graph of finite mean degree. We conclude with speculation on decision making with persistent collective oscillations. Throughout the paper, we emphasize analogies between methods of solution to our model and common intuition from diverse areas of physics, including statistical physics and electromagnetism. PMID:25493831

  1. Kinetic energy for the nuclear Yang-Mills collective model

    NASA Astrophysics Data System (ADS)

    Rosensteel, George; Sparks, Nick

    2015-10-01

    The Bohr-Mottelson-Frankfurt model of nuclear rotations and quadrupole vibrations is a foundational model in nuclear structure physics. The model, also called the geometrical collective model or simply GCM, has two hidden mathematical structures, one Lie group theoretic and the other differential geometric. Although the group structure has been understood for some time, the geometric structure is a new unexplored feature that shares the same mathematical origin as Yang-Mills, viz., a vector bundle with a non-abelian structure group and a connection. Using the de Rham Laplacian ▵ = * d * d from differential geometry for the kinetic energy extends significantly the physical scope of the GCM model. This Laplacian contains a ``magnetic'' term due to the coupling between base manifold rotational and fiber vorticity degrees of freedom. When the connection specializes to irrotational flow, the Laplacian reduces to the Bohr-Mottelson kinetic energy operator. More generally, the connection yields a moment of inertia that is intermediate between the extremes of irrotational flow and rigid body motion.

  2. Simple model for multiple-choice collective decision making

    NASA Astrophysics Data System (ADS)

    Lee, Ching Hua; Lucas, Andrew

    2014-11-01

    We describe a simple model of heterogeneous, interacting agents making decisions between n ≥2 discrete choices. For a special class of interactions, our model is the mean field description of random field Potts-like models and is effectively solved by finding the extrema of the average energy E per agent. In these cases, by studying the propagation of decision changes via avalanches, we argue that macroscopic dynamics is well captured by a gradient flow along E . We focus on the permutation symmetric case, where all n choices are (on average) the same, and spontaneous symmetry breaking (SSB) arises purely from cooperative social interactions. As examples, we show that bimodal heterogeneity naturally provides a mechanism for the spontaneous formation of hierarchies between decisions and that SSB is a preferred instability to discontinuous phase transitions between two symmetric points. Beyond the mean field limit, exponentially many stable equilibria emerge when we place this model on a graph of finite mean degree. We conclude with speculation on decision making with persistent collective oscillations. Throughout the paper, we emphasize analogies between methods of solution to our model and common intuition from diverse areas of physics, including statistical physics and electromagnetism.

  3. Modelling the emergence of coordinated collective motion by minimizing dissatisfaction.

    PubMed

    Quera, Vicenç; Beltran, Francesc S; Gimeno, Elisabet

    2016-01-01

    Coordinated collective motion (CCM) has been recently studied using agent-based simulations by applying three behavioural rules: repulsion, attraction and alignment. But these rules are so similar to the expected group behaviour that it can hardly be labelled emergent. We developed an agent-based model that produces CCM using a set of low-level dyadic interaction rules. The agents change their positions with regard to other agents in order to minimize their own dissatisfaction with their inter-individual distances. To test the emergence of CCM, several simulation experiments were performed. The results show that the agents were able to achieve CCM after a few thousand time steps, and that the bigger the area perceived by them, the more coordinated and cohesive the group motion became. An increased memory span and capacity to remember other agents' identities improved cohesion and coordination. The relationship with biological referents is discussed. PMID:26626359

  4. Fog collection and deposition modelling - EcoCatch Lunz

    NASA Astrophysics Data System (ADS)

    Koller, M. W.; Ramírez-Santa Cruz, C.; Leder, K.; Bauer, H.; Dorninger, M.; Hofhansl, F.; Wanek, W.; Kasper-Giebl, A.

    2010-07-01

    The area of Lunz am See (N 047.855°, E 015.068°, 650 m a.s.l.) in Lower Austria has been subject to long term monitoring of meteorological parameters as well as wet deposition. Even though Lunz is known for its good air quality, with about 200 days of precipitation per year reaching an annual average of 1500 mm deposition, immission fluxes reach levels of critical loads. For instance, nitrogen input from wet deposition of nitrate and ammonium is > 14 kg ha-1 a-1, and sulphur input from sulphate is 5 kg ha-1 a-1. In the framework of the EcoCatch project1) wet, dry and occult deposition have been investigated in detail in an alluvial forest near the Biological Station (Lunz/See) since September 2008. The overall contribution of dry and occult deposition was expected to be comparably low and only of importance in times of decreased wet deposition. Collection of fog samples was performed with an active fog sampler, regulated by a Vaisala PWD-12 sensor monitoring visibility. Temperature, relative humidity, wind speed and direction were logged by a HOBO weather station. Filter stacks were used for sampling of aerosol particles and gaseous components and a Wet And Dry Only Sampler (WADOS) was used to sample precipitation. Solute analysis was carried out via ion chromatography. Alkali and earth alkali metals, chloride as well as ammonium, sulphate and nitrate were quantified in rain, aerosol and fog samples on an event basis. In addition dry deposition included nitrogen oxide and dioxide, sulphur dioxide and ammonia measurements. A site specific relation of liquid water content (LWC) to visibility was established using the collection rate and the known collection efficiency of the fog sampler. A modified version of the fog deposition resistance model devised by G.M. Lovett was used to quantify occult deposition onto the alluvial forest. The surface area index of local vegetation was measured with a SunScan System and tree height was determined using a Vertex IV

  5. Collectivity in the light xenon isotopes: A shell model study

    SciTech Connect

    Caurier, E.; Nowacki, F.; Sieja, K.; Poves, A.

    2010-12-15

    The lightest xenon isotopes are studied in the shell model framework, within a valence space that comprises all the orbits lying between the magic closures N=Z=50 and N=Z=82. The calculations produce collective deformed structures of triaxial nature that encompass nicely the known experimental data. Predictions are made for the (still unknown) N=Z nucleus {sup 108}Xe. The results are interpreted in terms of the competition between the quadrupole correlations enhanced by the pseudo-SU(3) structure of the positive parity orbits and the pairing correlations brought in by the 0h{sub 11/2} orbit. We also have studied the effect of the excitations from the {sup 100}Sn core on our predictions. We show that the backbending in this region is due to the alignment of two particles in the 0h{sub 11/2} orbit. In the N=Z case, one neutron and one proton align to J=11 and T=0. In {sup 110,112}Xe the alignment begins in the J=10, T=1 channel and it is dominantly of neutron-neutron type. Approaching the band termination the alignment of a neutron-proton pair to J=11 and T=0 takes over. In a more academic mood, we have studied the role of the isovector and isoscalar pairing correlations on the structure on the yrast bands of {sup 108,110}Xe and examined the possible existence of isovector and isoscalar pairing condensates in these N{approx}{approx}Z nuclei.

  6. California Cultures: Implementing a Model for Virtual Collections

    ERIC Educational Resources Information Center

    Guerard, Genie; Chandler, Robin L.

    2006-01-01

    This article highlights the California Cultures Project as a case study examining the architecture and framework required to support the deployment of digital objects as virtual collections at the California Digital Library. Chronologically arranged, it describes the Online Archive of California (OAC) Working Group's functional requirements for…

  7. Data Collection and Cost Modeling for Library Circulation Systems.

    ERIC Educational Resources Information Center

    Bourne, Charles P.

    The objectives of the study leading to this report were to review, analyze and summarize published library cost data; and to develop a cost model and a methodology for reporting data in a more consistent and useful way. The cost model and reporting procedure were developed and tested on the circulation system of three libraries: a large university…

  8. Endogenous Crisis Waves: Stochastic Model with Synchronized Collective Behavior

    NASA Astrophysics Data System (ADS)

    Gualdi, Stanislao; Bouchaud, Jean-Philippe; Cencetti, Giulia; Tarzia, Marco; Zamponi, Francesco

    2015-02-01

    We propose a simple framework to understand commonly observed crisis waves in macroeconomic agent-based models, which is also relevant to a variety of other physical or biological situations where synchronization occurs. We compute exactly the phase diagram of the model and the location of the synchronization transition in parameter space. Many modifications and extensions can be studied, confirming that the synchronization transition is extremely robust against various sources of noise or imperfections.

  9. Boolean modeling of collective effects in complex networks.

    PubMed

    Norrell, Johannes; Socolar, Joshua E S

    2009-06-01

    Complex systems are often modeled as Boolean networks in attempts to capture their logical structure and reveal its dynamical consequences. Approximating the dynamics of continuous variables by discrete values and Boolean logic gates may, however, introduce dynamical possibilities that are not accessible to the original system. We show that large random networks of variables coupled through continuous transfer functions often fail to exhibit the complex dynamics of corresponding Boolean models in the disordered (chaotic) regime, even when each individual function appears to be a good candidate for Boolean idealization. A suitably modified Boolean theory explains the behavior of systems in which information does not propagate faithfully down certain chains of nodes. Model networks incorporating calculated or directly measured transfer functions reported in the literature on transcriptional regulation of genes are described by the modified theory. PMID:19658525

  10. Pricing Models and Payment Schemes for Library Collections.

    ERIC Educational Resources Information Center

    Stern, David

    2002-01-01

    Discusses new pricing and payment options for libraries in light of online products. Topics include alternative cost models rather than traditional subscriptions; use-based pricing; changes in scholarly communication due to information technology; methods to determine appropriate charges for different organizations; consortial plans; funding; and…

  11. The Diversity Challenge: A Collection of Model Programs.

    ERIC Educational Resources Information Center

    Mellander, Gustavo A., Ed.; Prochaska, Fred, Ed.

    Model programs designed to promote diversity within the West Valley-Mission Community College District (WVMCCD) in California are discussed and described in this report. First, an introductory chapter, "The Importance of Cultural Issues to Higher Education," by Gustavo A. Mellander and Fred Prochaska, reviews the diversity recommendations of the…

  12. Comparative analysis of data collection methods for individualized modeling of radiologists' visual similarity judgments

    SciTech Connect

    Tourassi, Georgia; Xu, Songhua; Yoon, Hong-Jun; Morin-Ducote, Garnetta; Hudson, Kathy

    2013-01-01

    Rationale and Objectives: We conducted an observer study to investigate how the data collection method affects the efficacy of modeling individual radiologists judgments regarding the perceptual similarity of breast masses on mammograms. Materials and Methods: Institutional review board approval was obtained prior to the study. Six observers of variable experience levels in breast imaging were recruited to assess the perceptual similarity of mammographic masses. The observers subjective judgments were collected using: (i) a rating method, (ii) a preference method, and (iii) a hybrid method combining rating and ranking. Personalized user models were developed with the collected data to predict observers opinions. The relative efficacy of each data collection method was assessed based on the classification accuracy of the resulting user models. Results: The hybrid data collection method produced significantly more accurate individualized user models of perceptual opinions with comparable and sometimes better time efficiency than the other two data collection methods. The user models derived from hybrid data were clearly superior even when developed with a dramatically smaller number of training cases. Conclusions: A hybrid method combining rating and ranking is an intuitive and efficient way for collecting subjective similarity judgments to model human perceptual opinions with a higher accuracy than other more commonly used data collection methods.

  13. Extension of the ADC Charge-Collection Model to Include Multiple Junctions

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    2011-01-01

    The ADC model is a charge-collection model derived for simple p-n junction silicon diodes having a single reverse-biased p-n junction at one end and an ideal substrate contact at the other end. The present paper extends the model to include multiple junctions, and the goal is to estimate how collected charge is shared by the different junctions.

  14. Energy and time modelling of kerbside waste collection: Changes incurred when adding source separated food waste.

    PubMed

    Edwards, Joel; Othman, Maazuza; Burn, Stewart; Crossin, Enda

    2016-10-01

    The collection of source separated kerbside municipal FW (SSFW) is being incentivised in Australia, however such a collection is likely to increase the fuel and time a collection truck fleet requires. Therefore, waste managers need to determine whether the incentives outweigh the cost. With literature scarcely describing the magnitude of increase, and local parameters playing a crucial role in accurately modelling kerbside collection; this paper develops a new general mathematical model that predicts the energy and time requirements of a collection regime whilst incorporating the unique variables of different jurisdictions. The model, Municipal solid waste collect (MSW-Collect), is validated and shown to be more accurate at predicting fuel consumption and trucks required than other common collection models. When predicting changes incurred for five different SSFW collection scenarios, results show that SSFW scenarios require an increase in fuel ranging from 1.38% to 57.59%. There is also a need for additional trucks across most SSFW scenarios tested. All SSFW scenarios are ranked and analysed in regards to fuel consumption; sensitivity analysis is conducted to test key assumptions. PMID:27396681

  15. Collective Philanthropy: Describing and Modeling the Ecology of Giving

    PubMed Central

    Gottesman, William L.; Reagan, Andrew James; Dodds, Peter Sheridan

    2014-01-01

    Reflective of income and wealth distributions, philanthropic gifting appears to follow an approximate power-law size distribution as measured by the size of gifts received by individual institutions. We explore the ecology of gifting by analysing data sets of individual gifts for a diverse group of institutions dedicated to education, medicine, art, public support, and religion. We find that the detailed forms of gift-size distributions differ across but are relatively constant within charity categories. We construct a model for how a donor's income affects their giving preferences in different charity categories, offering a mechanistic explanation for variations in institutional gift-size distributions. We discuss how knowledge of gift-sized distributions may be used to assess an institution's gift-giving profile, to help set fundraising goals, and to design an institution-specific giving pyramid. PMID:24983864

  16. Collective coordinate approximation to the scattering of solitons in modified NLS and sine-Gordon models

    NASA Astrophysics Data System (ADS)

    Baron, H. E.; Zakrzewski, W. J.

    2016-06-01

    We investigate the validity of collective coordinate approximations to the scattering of two solitons in several classes of (1+1) dimensional field theory models. We consider models which are deformations of the sine-Gordon (SG) or the nonlinear Schrödinger (NLS) model which posses soliton solutions (which are topological (SG) or non-topological (NLS)). Our deformations preserve their topology (SG), but change their integrability properties, either completely or partially (models become `quasi-integrable').

  17. Acting in solidarity: Testing an extended dual pathway model of collective action by bystander group members.

    PubMed

    Saab, Rim; Tausch, Nicole; Spears, Russell; Cheung, Wing-Yee

    2015-09-01

    We examined predictors of collective action among bystander group members in solidarity with a disadvantaged group by extending the dual pathway model of collective action, which proposes one efficacy-based and one emotion-based path to collective action (Van Zomeren, Spears, Fischer, & Leach, 2004). Based on two proposed functions of social identity performance (Klein, Spears, & Reicher, 2007), we distinguished between the efficacy of collective action at consolidating the identity of a protest movement and its efficacy at achieving social change (political efficacy). We expected identity consolidation efficacy to positively predict collective action tendencies directly and indirectly via political efficacy. We also expected collective action tendencies to be positively predicted by moral outrage and by sympathy in response to disadvantaged outgroup's suffering. These hypotheses were supported in two surveys examining intentions to protest for Palestine in Britain (Study 1), and intentions to attend the June 4th vigil in Hong Kong to commemorate the Tiananmen massacre among a sample of Hong Kong citizens (Study 2). The contributions of these findings to research on the dual pathway model of collective action and the different functions of collective action are discussed. PMID:25406712

  18. Academic Optimism and Collective Responsibility: An Organizational Model of the Dynamics of Student Achievement

    ERIC Educational Resources Information Center

    Wu, Jason H.

    2013-01-01

    This study was designed to examine the construct of academic optimism and its relationship with collective responsibility in a sample of Taiwan elementary schools. The construct of academic optimism was tested using confirmatory factor analysis, and the whole structural model was tested with a structural equation modeling analysis. The data were…

  19. Collective Labor Supply: A Single-Equation Model and Some Evidence from French Data

    ERIC Educational Resources Information Center

    Donni, Olivier; Moreau, Nicolas

    2007-01-01

    In Chiappori's (1988) collective model of labor supply, hours of work are supposed flexible. In many countries, however, male labor supply does not vary much. In that case, the husband's labor supply is no longer informative about the household decision process and individual preferences. To identify structural components of the model, additional…

  20. Turbulent flow model for vapor collection efficiency of a high-purity silicon reactor

    NASA Technical Reports Server (NTRS)

    Srivastava, R.; Gould, R. K.

    1985-01-01

    In this study a mathematical model and a computer code based on this model was developed to allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon. Specifically, the model formulated describes the silicon vapor separation/collection from the developing turbulent flow stream within reactors of the Westinghouse type. Migration of the silicon vapor to the reactor walls was described by the parametric solutions presented here, in order to reduce the experimentation necessary in the design of such reactors. Calculations relating to the collection efficiencies of such reactors are presented as a function of the reactor throughflow and distance along its length.

  1. Real-time inverse-model analysis and control on data collection

    NASA Astrophysics Data System (ADS)

    Vesselinov, V. V.; Robinson, B. A.; Vrugt, J. A.; Zyvoloski, G. A.

    2005-12-01

    Sophisticated numerical models are commonly used to simulate fluid and chemical flow in the subsurface. The science of flow in porous media is composed of general physical principles (transferable knowledge) and site-specific details. All sites are unique, so even if the physics is well understood, we need detailed, site-specific information to develop a model for each site (subsurface heterogeneity, initial and boundary conditions, etc.). In this respect, at each new site, we "start over". The most time- and resource-consuming step in reducing predictive uncertainty bounds in subsurface systems is the process of uncovering the site-specific details. The current paradigm is to perform a lengthy reconnaissance phase to understand the site, followed by additional data collection and modeling to synthesize the information. Model development methods are slow and labor-intensive for complex sites; therefore, model results generally lag behind the data collection by a considerable length of time. This delay limits the usefulness of the model as a tool to guide data collection: any given iteration of the model is out of date by the time it is completed. The whole process is unacceptably protracted in an era in which, for example, in the U.S. alone we may ultimately need hundreds of sites to implement CO2 geologic sequestration. Our technical capabilities for efficiently collecting and organizing subsurface data have progressed recently with the advent of modern data collection and transmission systems. However, our ability to process this information in the form of numerical models has lagged behind. We propose a new paradigm for the development of complex subsurface flow and transport models in which the inverse analysis is performed in real time, simultaneously with the data collection. Furthermore, we propose to use the inverse model to control the data collection or the operating conditions of an extraction system in real time. This is extremely important because post

  2. Modeling the Efficiency of a Magnetic Needle for Collecting Magnetic Cells

    PubMed Central

    Butler, Kimberly S; Adolphi, Natalie L.; Bryant, H C; Lovato, Debbie M; Larson, Richard S; Flynn, Edward R

    2014-01-01

    As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in 1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and 2) water in which 3, 5, 10 and 100 % of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency vs. time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium. PMID:24874577

  3. Modeling the efficiency of a magnetic needle for collecting magnetic cells.

    PubMed

    Butler, Kimberly S; Adolphi, Natalie L; Bryant, H C; Lovato, Debbie M; Larson, Richard S; Flynn, Edward R

    2014-07-01

    As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium. PMID:24874577

  4. Modeling the efficiency of a magnetic needle for collecting magnetic cells

    NASA Astrophysics Data System (ADS)

    Butler, Kimberly S.; Adolphi, Natalie L.; Bryant, H. C.; Lovato, Debbie M.; Larson, Richard S.; Flynn, Edward R.

    2014-07-01

    As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium.

  5. Model-driven approach to data collection and reporting for quality improvement

    PubMed Central

    Curcin, Vasa; Woodcock, Thomas; Poots, Alan J.; Majeed, Azeem; Bell, Derek

    2014-01-01

    Continuous data collection and analysis have been shown essential to achieving improvement in healthcare. However, the data required for local improvement initiatives are often not readily available from hospital Electronic Health Record (EHR) systems or not routinely collected. Furthermore, improvement teams are often restricted in time and funding thus requiring inexpensive and rapid tools to support their work. Hence, the informatics challenge in healthcare local improvement initiatives consists of providing a mechanism for rapid modelling of the local domain by non-informatics experts, including performance metric definitions, and grounded in established improvement techniques. We investigate the feasibility of a model-driven software approach to address this challenge, whereby an improvement model designed by a team is used to automatically generate required electronic data collection instruments and reporting tools. To that goal, we have designed a generic Improvement Data Model (IDM) to capture the data items and quality measures relevant to the project, and constructed Web Improvement Support in Healthcare (WISH), a prototype tool that takes user-generated IDM models and creates a data schema, data collection web interfaces, and a set of live reports, based on Statistical Process Control (SPC) for use by improvement teams. The software has been successfully used in over 50 improvement projects, with more than 700 users. We present in detail the experiences of one of those initiatives, Chronic Obstructive Pulmonary Disease project in Northwest London hospitals. The specific challenges of improvement in healthcare are analysed and the benefits and limitations of the approach are discussed. PMID:24874182

  6. Model-driven approach to data collection and reporting for quality improvement.

    PubMed

    Curcin, Vasa; Woodcock, Thomas; Poots, Alan J; Majeed, Azeem; Bell, Derek

    2014-12-01

    Continuous data collection and analysis have been shown essential to achieving improvement in healthcare. However, the data required for local improvement initiatives are often not readily available from hospital Electronic Health Record (EHR) systems or not routinely collected. Furthermore, improvement teams are often restricted in time and funding thus requiring inexpensive and rapid tools to support their work. Hence, the informatics challenge in healthcare local improvement initiatives consists of providing a mechanism for rapid modelling of the local domain by non-informatics experts, including performance metric definitions, and grounded in established improvement techniques. We investigate the feasibility of a model-driven software approach to address this challenge, whereby an improvement model designed by a team is used to automatically generate required electronic data collection instruments and reporting tools. To that goal, we have designed a generic Improvement Data Model (IDM) to capture the data items and quality measures relevant to the project, and constructed Web Improvement Support in Healthcare (WISH), a prototype tool that takes user-generated IDM models and creates a data schema, data collection web interfaces, and a set of live reports, based on Statistical Process Control (SPC) for use by improvement teams. The software has been successfully used in over 50 improvement projects, with more than 700 users. We present in detail the experiences of one of those initiatives, Chronic Obstructive Pulmonary Disease project in Northwest London hospitals. The specific challenges of improvement in healthcare are analysed and the benefits and limitations of the approach are discussed. PMID:24874182

  7. Collective motion of motile cilia: from human airways to model systems

    NASA Astrophysics Data System (ADS)

    Cicuta, Pietro; Feriani, Luigi; Chioccioli, Maurizio; Kotar, Jurij

    Mammalian airways are a fantastic playground of nonlinear phenomena, from the function of individual active filaments, to the emerging collective behaviour, to the rheology of the mucus solution surrounding cilia. We have been investigating the fundamental physics of this system through a variety of model system approaches, both experimental and computational. In the last year we have started measurements on living human cells, observing cilia shape during beating, and measuring speed and coherence of the collective dynamics. We report on significant differences in the collective motion in ciliated cell carpets from a variety of diseases, and we attempt to reconcile the collective dynamical phenotypes to the properties of individual filaments and the mechanics of the environment.

  8. Exploring the dynamics of collective cognition using a computational model of cognitive dissonance

    NASA Astrophysics Data System (ADS)

    Smart, Paul R.; Sycara, Katia; Richardson, Darren P.

    2013-05-01

    The socially-distributed nature of cognitive processing in a variety of organizational settings means that there is increasing scientific interest in the factors that affect collective cognition. In military coalitions, for example, there is a need to understand how factors such as communication network topology, trust, cultural differences and the potential for miscommunication affects the ability of distributed teams to generate high quality plans, to formulate effective decisions and to develop shared situation awareness. The current paper presents a computational model and associated simulation capability for performing in silico experimental analyses of collective sensemaking. This model can be used in combination with the results of human experimental studies in order to improve our understanding of the factors that influence collective sensemaking processes.

  9. Dynamical Modeling of Collective Behavior from Pigeon Flight Data: Flock Cohesion and Dispersion

    PubMed Central

    Xu, Xiao-Ke; Small, Michael

    2012-01-01

    Several models of flocking have been promoted based on simulations with qualitatively naturalistic behavior. In this paper we provide the first direct application of computational modeling methods to infer flocking behavior from experimental field data. We show that this approach is able to infer general rules for interaction, or lack of interaction, among members of a flock or, more generally, any community. Using experimental field measurements of homing pigeons in flight we demonstrate the existence of a basic distance dependent attraction/repulsion relationship and show that this rule is sufficient to explain collective behavior observed in nature. Positional data of individuals over time are used as input data to a computational algorithm capable of building complex nonlinear functions that can represent the system behavior. Topological nearest neighbor interactions are considered to characterize the components within this model. The efficacy of this method is demonstrated with simulated noisy data generated from the classical (two dimensional) Vicsek model. When applied to experimental data from homing pigeon flights we show that the more complex three dimensional models are capable of simulating trajectories, as well as exhibiting realistic collective dynamics. The simulations of the reconstructed models are used to extract properties of the collective behavior in pigeons, and how it is affected by changing the initial conditions of the system. Our results demonstrate that this approach may be applied to construct models capable of simulating trajectories and collective dynamics using experimental field measurements of herd movement. From these models, the behavior of the individual agents (animals) may be inferred. PMID:22479176

  10. Dynamical modeling of collective behavior from pigeon flight data: flock cohesion and dispersion.

    PubMed

    Dieck Kattas, Graciano; Xu, Xiao-Ke; Small, Michael

    2012-01-01

    Several models of flocking have been promoted based on simulations with qualitatively naturalistic behavior. In this paper we provide the first direct application of computational modeling methods to infer flocking behavior from experimental field data. We show that this approach is able to infer general rules for interaction, or lack of interaction, among members of a flock or, more generally, any community. Using experimental field measurements of homing pigeons in flight we demonstrate the existence of a basic distance dependent attraction/repulsion relationship and show that this rule is sufficient to explain collective behavior observed in nature. Positional data of individuals over time are used as input data to a computational algorithm capable of building complex nonlinear functions that can represent the system behavior. Topological nearest neighbor interactions are considered to characterize the components within this model. The efficacy of this method is demonstrated with simulated noisy data generated from the classical (two dimensional) Vicsek model. When applied to experimental data from homing pigeon flights we show that the more complex three dimensional models are capable of simulating trajectories, as well as exhibiting realistic collective dynamics. The simulations of the reconstructed models are used to extract properties of the collective behavior in pigeons, and how it is affected by changing the initial conditions of the system. Our results demonstrate that this approach may be applied to construct models capable of simulating trajectories and collective dynamics using experimental field measurements of herd movement. From these models, the behavior of the individual agents (animals) may be inferred. PMID:22479176

  11. A Field-Study/Data-Collection Model for Developing an Education-Business Liaison Network.

    ERIC Educational Resources Information Center

    Church, Olive D.

    Thirteen Wyoming teachers and counselors interviewed managers in 215 businesses covering 9,515 jobs. This field study served as a basis for developing a field study-data collection model to be used in establishing an education-business liaison network. Each interviewer participating in the study was instructed to contact from 10 to 20 local…

  12. Collective coordinate approximation to the scattering of solitons in the (1+1) dimensional NLS model

    NASA Astrophysics Data System (ADS)

    Baron, H. E.; Luchini, G.; Zakrzewski, W. J.

    2014-07-01

    We present a collective coordinate approximation to model the dynamics of two interacting nonlinear Schrödinger solitons. We discuss the accuracy of this approximation by comparing our results with those of the full numerical simulations and find that the approximation is remarkably accurate when the solitons are some distance apart, and quite reasonable also during their interaction.

  13. Collective Bargaining and the Community College: A Process Model for Management Teams.

    ERIC Educational Resources Information Center

    Langan, Alfred "Bud"; And Others

    The model presented in this monograph was designed to aid state and district school systems and college administrators in dealing with the challenge of faculty collective bargaining in Washington community colleges. First, Chapter 1 provides a historical analysis of the laws and statutes relating to negotiations in the state's community colleges.…

  14. MODEL UNCERTAINTY ANALYSIS, FIELD DATA COLLECTION AND ANALYSIS OF CONTAMINATED VAPOR INTRUSION INTO BUILDINGS

    EPA Science Inventory

    To address uncertainty associated with the evaluation of vapor intrusion problems we are working on a three part strategy that includes: evaluation of uncertainty in model-based assessments; collection of field data and assessment of sites using EPA and state protocols.

  15. Development of model for analysing respective collections of intended hematopoietic stem cells and harvests of unintended mature cells in apheresis for autologous hematopoietic stem cell collection.

    PubMed

    Hequet, O; Le, Q H; Rodriguez, J; Dubost, P; Revesz, D; Clerc, A; Rigal, D; Salles, G; Coiffier, B

    2014-04-01

    Hematopoietic stem cells (HSCs) required to perform peripheral hematopoietic autologous stem cell transplantation (APBSCT) can be collected by processing several blood volumes (BVs) in leukapheresis sessions. However, this may cause granulocyte harvest in graft and decrease in patient's platelet blood level. Both consequences may induce disturbances in patient. One apheresis team's current purpose is to improve HSC collection by increasing HSC collection and prevent increase in granulocyte and platelet harvests. Before improving HSC collection it seemed important to know more about the way to harvest these types of cells. The purpose of our study was to develop a simple model for analysing respective collections of intended CD34+ cells among HSC (designated here as HSC) and harvests of unintended platelets or granulocytes among mature cells (designated here as mature cells) considering the number of BVs processed and factors likely to influence cell collection or harvest. For this, we processed 1, 2 and 3 BVs in 59 leukapheresis sessions and analysed corresponding collections and harvests with a referent device (COBE Spectra). First we analysed the amounts of HSC collected and mature cells harvested and second the evolution of the respective shares of HSC and mature cells collected or harvested throughout the BV processes. HSC collections and mature cell harvests increased globally (p<0.0001) and their respective shares remained stable throughout the BV processes (p non-significant). We analysed the role of intrinsic (patient's features) and extrinsic (features before starting leukapheresis sessions) factors in collections and harvests, which showed that only pre-leukapheresis blood levels (CD34+cells and platelets) influenced both cell collections and harvests (CD34+cells and platelets) (p<0.001) and shares of HSC collections and mature unintended cells harvests (p<0.001) throughout the BV processes. Altogether, our results suggested that the main factors likely

  16. Flocking and Turning: a New Model for Self-organized Collective Motion

    NASA Astrophysics Data System (ADS)

    Cavagna, Andrea; Del Castello, Lorenzo; Giardina, Irene; Grigera, Tomas; Jelic, Asja; Melillo, Stefania; Mora, Thierry; Parisi, Leonardo; Silvestri, Edmondo; Viale, Massimiliano; Walczak, Aleksandra M.

    2015-02-01

    Birds in a flock move in a correlated way, resulting in large polarization of velocities. A good understanding of this collective behavior exists for linear motion of the flock. Yet observing actual birds, the center of mass of the group often turns giving rise to more complicated dynamics, still keeping strong polarization of the flock. Here we propose novel dynamical equations for the collective motion of polarized animal groups that account for correlated turning including solely social forces. We exploit rotational symmetries and conservation laws of the problem to formulate a theory in terms of generalized coordinates of motion for the velocity directions akin to a Hamiltonian formulation for rotations. We explicitly derive the correspondence between this formulation and the dynamics of the individual velocities, thus obtaining a new model of collective motion. In the appropriate overdamped limit we recover the well-known Vicsek model, which dissipates rotational information and does not allow for polarized turns. Although the new model has its most vivid success in describing turning groups, its dynamics is intrinsically different from previous ones in a wide dynamical regime, while reducing to the hydrodynamic description of Toner and Tu at very large length-scales. The derived framework is therefore general and it may describe the collective motion of any strongly polarized active matter system.

  17. Models in animal collective decision-making: information uncertainty and conflicting preferences.

    PubMed

    Conradt, Larissa

    2012-04-01

    Collective decision-making plays a central part in the lives of many social animals. Two important factors that influence collective decision-making are information uncertainty and conflicting preferences. Here, I bring together, and briefly review, basic models relating to animal collective decision-making in situations with information uncertainty and in situations with conflicting preferences between group members. The intention is to give an overview about the different types of modelling approaches that have been employed and the questions that they address and raise. Despite the use of a wide range of different modelling techniques, results show a coherent picture, as follows. Relatively simple cognitive mechanisms can lead to effective information pooling. Groups often face a trade-off between decision accuracy and speed, but appropriate fine-tuning of behavioural parameters could achieve high accuracy while maintaining reasonable speed. The right balance of interdependence and independence between animals is crucial for maintaining group cohesion and achieving high decision accuracy. In conflict situations, a high degree of decision-sharing between individuals is predicted, as well as transient leadership and leadership according to needs and physiological status. Animals often face crucial trade-offs between maintaining group cohesion and influencing the decision outcome in their own favour. Despite the great progress that has been made, there remains one big gap in our knowledge: how do animals make collective decisions in situations when information uncertainty and conflict of interest operate simultaneously? PMID:23565335

  18. Models in animal collective decision-making: information uncertainty and conflicting preferences

    PubMed Central

    Conradt, Larissa

    2012-01-01

    Collective decision-making plays a central part in the lives of many social animals. Two important factors that influence collective decision-making are information uncertainty and conflicting preferences. Here, I bring together, and briefly review, basic models relating to animal collective decision-making in situations with information uncertainty and in situations with conflicting preferences between group members. The intention is to give an overview about the different types of modelling approaches that have been employed and the questions that they address and raise. Despite the use of a wide range of different modelling techniques, results show a coherent picture, as follows. Relatively simple cognitive mechanisms can lead to effective information pooling. Groups often face a trade-off between decision accuracy and speed, but appropriate fine-tuning of behavioural parameters could achieve high accuracy while maintaining reasonable speed. The right balance of interdependence and independence between animals is crucial for maintaining group cohesion and achieving high decision accuracy. In conflict situations, a high degree of decision-sharing between individuals is predicted, as well as transient leadership and leadership according to needs and physiological status. Animals often face crucial trade-offs between maintaining group cohesion and influencing the decision outcome in their own favour. Despite the great progress that has been made, there remains one big gap in our knowledge: how do animals make collective decisions in situations when information uncertainty and conflict of interest operate simultaneously? PMID:23565335

  19. Modeling and analysis of collective cell migration in an in vivo three-dimensional environment.

    PubMed

    Cai, Danfeng; Dai, Wei; Prasad, Mohit; Luo, Junjie; Gov, Nir S; Montell, Denise J

    2016-04-12

    A long-standing question in collective cell migration has been what might be the relative advantage of forming a cluster over migrating individually. Does an increase in the size of a collectively migrating group of cells enable them to sample the chemical gradient over a greater distance because the difference between front and rear of a cluster would be greater than for single cells? We combined theoretical modeling with experiments to study collective migration of the border cells in-between nurse cells in the Drosophila egg chamber. We discovered that cluster size is positively correlated with migration speed, up to a particular point above which speed plummets. This may be due to the effect of viscous drag from surrounding nurse cells together with confinement of all of the cells within a stiff extracellular matrix. The model predicts no relationship between cluster size and velocity for cells moving on a flat surface, in contrast to movement within a 3D environment. Our analyses also suggest that the overall chemoattractant profile in the egg chamber is likely to be exponential, with the highest concentration in the oocyte. These findings provide insights into collective chemotaxis by combining theoretical modeling with experimentation. PMID:27035964

  20. A model for cell density effect on stress fiber alignment and collective directional migration

    NASA Astrophysics Data System (ADS)

    Abeddoust, Mohammad; Shamloo, Amir

    2015-12-01

    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes—including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements—are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during collective cell chemotaxis, such as cell density, cytoskeleton organization, stress fiber reorientations, and intracellular forces. The results suggest that increasing the cell density causes the cell-cell interactions to affect the orientation of stress fibers throughout the cytoskeleton and makes the stress fibers more aligned in the direction of the imposed concentration gradient. This improved alignment of the stress fibers correlates with the intensification of the intracellular forces transferred in the gradient direction; this improves the cell group migration. Comparison of the obtained results with available experimental observations of collective chemotaxis of endothelial cells shows an interesting agreement.

  1. Correlations between statistical models of robotically collected kinematics and clinical measures of upper extremity function.

    PubMed

    Rohafza, Maryam; Fluet, Gerard G; Qiu, Qinyin; Adamovich, Sergei

    2012-01-01

    One of the obstacles in the development of rehabilitation robotics has been inadequacy in the measurement of treatment effects due to interventions. A measurement tool that will efficiently produce a large reliable sample of measurements collected during a single session that can also produce a rich set of data which reflects a subject's ability to perform meaningful functional activities has not been developed. This paper presents three linear regression models generated from seven kinematic measures collected during the performance of virtually simulated rehabilitation activities that were integrated with haptic robots by 19 persons with upper extremity hemiparesis due to chronic stroke. One of these models demonstrated a statistically significant correlation with the subjects' scores on the Jebsen Test of Hand Function (JTHF), a battery of six standardized upper extremity functional activities. The second and third models demonstrated a statistically significant correlation with the subjects' change scores on the JTHF. PMID:23366834

  2. Onset of collective motion in locusts is captured by a minimal model.

    PubMed

    Dyson, Louise; Yates, Christian A; Buhl, Jerome; McKane, Alan J

    2015-11-01

    We present a minimal model to describe the onset of collective motion seen when a population of locusts are placed in an annular arena. At low densities motion is disordered, while at high densities locusts march in a common direction, which may reverse during the experiment. The data are well captured by an individual-based model, in which demographic noise leads to the observed density-dependent effects. By fitting the model parameters to equation-free coefficients, we give a quantitative comparison, showing time series, stationary distributions, and the mean switching times between states. PMID:26651724

  3. Onset of collective motion in locusts is captured by a minimal model

    NASA Astrophysics Data System (ADS)

    Dyson, Louise; Yates, Christian A.; Buhl, Jerome; McKane, Alan J.

    2015-11-01

    We present a minimal model to describe the onset of collective motion seen when a population of locusts are placed in an annular arena. At low densities motion is disordered, while at high densities locusts march in a common direction, which may reverse during the experiment. The data are well captured by an individual-based model, in which demographic noise leads to the observed density-dependent effects. By fitting the model parameters to equation-free coefficients, we give a quantitative comparison, showing time series, stationary distributions, and the mean switching times between states.

  4. HOCOMOCO: expansion and enhancement of the collection of transcription factor binding sites models.

    PubMed

    Kulakovskiy, Ivan V; Vorontsov, Ilya E; Yevshin, Ivan S; Soboleva, Anastasiia V; Kasianov, Artem S; Ashoor, Haitham; Ba-Alawi, Wail; Bajic, Vladimir B; Medvedeva, Yulia A; Kolpakov, Fedor A; Makeev, Vsevolod J

    2016-01-01

    Models of transcription factor (TF) binding sites provide a basis for a wide spectrum of studies in regulatory genomics, from reconstruction of regulatory networks to functional annotation of transcripts and sequence variants. While TFs may recognize different sequence patterns in different conditions, it is pragmatic to have a single generic model for each particular TF as a baseline for practical applications. Here we present the expanded and enhanced version of HOCOMOCO (http://hocomoco.autosome.ru and http://www.cbrc.kaust.edu.sa/hocomoco10), the collection of models of DNA patterns, recognized by transcription factors. HOCOMOCO now provides position weight matrix (PWM) models for binding sites of 601 human TFs and, in addition, PWMs for 396 mouse TFs. Furthermore, we introduce the largest up to date collection of dinucleotide PWM models for 86 (52) human (mouse) TFs. The update is based on the analysis of massive ChIP-Seq and HT-SELEX datasets, with the validation of the resulting models on in vivo data. To facilitate a practical application, all HOCOMOCO models are linked to gene and protein databases (Entrez Gene, HGNC, UniProt) and accompanied by precomputed score thresholds. Finally, we provide command-line tools for PWM and diPWM threshold estimation and motif finding in nucleotide sequences. PMID:26586801

  5. HOCOMOCO: expansion and enhancement of the collection of transcription factor binding sites models

    PubMed Central

    Kulakovskiy, Ivan V.; Vorontsov, Ilya E.; Yevshin, Ivan S.; Soboleva, Anastasiia V.; Kasianov, Artem S.; Ashoor, Haitham; Ba-alawi, Wail; Bajic, Vladimir B.; Medvedeva, Yulia A.; Kolpakov, Fedor A.; Makeev, Vsevolod J.

    2016-01-01

    Models of transcription factor (TF) binding sites provide a basis for a wide spectrum of studies in regulatory genomics, from reconstruction of regulatory networks to functional annotation of transcripts and sequence variants. While TFs may recognize different sequence patterns in different conditions, it is pragmatic to have a single generic model for each particular TF as a baseline for practical applications. Here we present the expanded and enhanced version of HOCOMOCO (http://hocomoco.autosome.ru and http://www.cbrc.kaust.edu.sa/hocomoco10), the collection of models of DNA patterns, recognized by transcription factors. HOCOMOCO now provides position weight matrix (PWM) models for binding sites of 601 human TFs and, in addition, PWMs for 396 mouse TFs. Furthermore, we introduce the largest up to date collection of dinucleotide PWM models for 86 (52) human (mouse) TFs. The update is based on the analysis of massive ChIP-Seq and HT-SELEX datasets, with the validation of the resulting models on in vivo data. To facilitate a practical application, all HOCOMOCO models are linked to gene and protein databases (Entrez Gene, HGNC, UniProt) and accompanied by precomputed score thresholds. Finally, we provide command-line tools for PWM and diPWM threshold estimation and motif finding in nucleotide sequences. PMID:26586801

  6. Computational model of collective nest selection by ants with heterogeneous acceptance thresholds.

    PubMed

    Masuda, Naoki; O'shea-Wheller, Thomas A; Doran, Carolina; Franks, Nigel R

    2015-06-01

    Collective decision-making is a characteristic of societies ranging from ants to humans. The ant Temnothorax albipennis is known to use quorum sensing to collectively decide on a new home; emigration to a new nest site occurs when the number of ants favouring the new site becomes quorate. There are several possible mechanisms by which ant colonies can select the best nest site among alternatives based on a quorum mechanism. In this study, we use computational models to examine the implications of heterogeneous acceptance thresholds across individual ants in collective nest choice behaviour. We take a minimalist approach to develop a differential equation model and a corresponding non-spatial agent-based model. We show, consistent with existing empirical evidence, that heterogeneity in acceptance thresholds is a viable mechanism for efficient nest choice behaviour. In particular, we show that the proposed models show speed-accuracy trade-offs and speed-cohesion trade-offs when we vary the number of scouts or the quorum threshold. PMID:26543578

  7. Computational model of collective nest selection by ants with heterogeneous acceptance thresholds

    PubMed Central

    Masuda, Naoki; O'shea-Wheller, Thomas A.; Doran, Carolina; Franks, Nigel R.

    2015-01-01

    Collective decision-making is a characteristic of societies ranging from ants to humans. The ant Temnothorax albipennis is known to use quorum sensing to collectively decide on a new home; emigration to a new nest site occurs when the number of ants favouring the new site becomes quorate. There are several possible mechanisms by which ant colonies can select the best nest site among alternatives based on a quorum mechanism. In this study, we use computational models to examine the implications of heterogeneous acceptance thresholds across individual ants in collective nest choice behaviour. We take a minimalist approach to develop a differential equation model and a corresponding non-spatial agent-based model. We show, consistent with existing empirical evidence, that heterogeneity in acceptance thresholds is a viable mechanism for efficient nest choice behaviour. In particular, we show that the proposed models show speed–accuracy trade-offs and speed–cohesion trade-offs when we vary the number of scouts or the quorum threshold. PMID:26543578

  8. Mapping out the solid waste generation and collection models: The case of Kampala City.

    PubMed

    Kinobe, Joel R; Niwagaba, Charles B; Gebresenbet, Girma; Komakech, Allan J; Vinnerås, Björn

    2015-02-01

    This paper presents a mapping of the waste collection systems in Kampala city, using geographical information system (GIS) ArcGIS mapping software. It discusses the existing models of waste collection to the final disposal destinations. It was found that food and yard wastes constitute 92.7% of the waste generated in Kampala. Recyclables and other special wastes constitute only 7.3% of the total waste, mainly because of the increased level of reuse and recycling activities. The generation rate of solid wastes was on average, 582, 169, 105, and 90 tons/day from poor areas, upscale wealthier areas, business centers, and market areas respectively. This tonnage of waste was collected, transported, and disposed of at the city landfill. The study found that in total, residential areas of poor people generate more waste than other categories stated earlier, mainly because of their large populations. In total, there were 133 unofficial temporary storage sites acknowledged by Kampala Capital City Authority (KCCA) but not formally designated, 59 illegal dump sites, and 35 officially recognized temporary waste storage locations. This paper presents large-scale data that can help with understanding the collection models and their influence on solid waste management in Kampala city, which could be used for similar cities in developing countries. PMID:25947055

  9. Modeling keratinocyte wound healing dynamics: Cell-cell adhesion promotes sustained collective migration.

    PubMed

    Nardini, John T; Chapnick, Douglas A; Liu, Xuedong; Bortz, David M

    2016-07-01

    The in vitro migration of keratinocyte cell sheets displays behavioral and biochemical similarities to the in vivo wound healing response of keratinocytes in animal model systems. In both cases, ligand-dependent Epidermal Growth Factor Receptor (EGFR) activation is sufficient to elicit collective cell migration into the wound. Previous mathematical modeling studies of in vitro wound healing assays assume that physical connections between cells have a hindering effect on cell migration, but biological literature suggests a more complicated story. By combining mathematical modeling and experimental observations of collectively migrating sheets of keratinocytes, we investigate the role of cell-cell adhesion during in vitro keratinocyte wound healing assays. We develop and compare two nonlinear diffusion models of the wound healing process in which cell-cell adhesion either hinders or promotes migration. Both models can accurately fit the leading edge propagation of cell sheets during wound healing when using a time-dependent rate of cell-cell adhesion strength. The model that assumes a positive role of cell-cell adhesion on migration, however, is robust to changes in the leading edge definition and yields a qualitatively accurate density profile. Using RNAi for the critical adherens junction protein, α-catenin, we demonstrate that cell sheets with wild type cell-cell adhesion expression maintain migration into the wound longer than cell sheets with decreased cell-cell adhesion expression, which fails to exhibit collective migration. Our modeling and experimental data thus suggest that cell-cell adhesion promotes sustained migration as cells pull neighboring cells into the wound during wound healing. PMID:27105673

  10. Modeling age-specific cancer incidences using logistic growth equations: implications for data collection.

    PubMed

    Shen, Xing-Rong; Feng, Rui; Chai, Jing; Cheng, Jing; Wang, De-Bin

    2014-01-01

    Large scale secular registry or surveillance systems have been accumulating vast data that allow mathematical modeling of cancer incidence and mortality rates. Most contemporary models in this regard use time series and APC (age-period-cohort) methods and focus primarily on predicting or analyzing cancer epidemiology with little attention being paid to implications for designing cancer registry, surveillance or evaluation initiatives. This research models age-specific cancer incidence rates using logistic growth equations and explores their performance under different scenarios of data completeness in the hope of deriving clues for reshaping relevant data collection. The study used China Cancer Registry Report 2012 as the data source. It employed 3-parameter logistic growth equations and modeled the age-specific incidence rates of all and the top 10 cancers presented in the registry report. The study performed 3 types of modeling, namely full age-span by fitting, multiple 5-year- segment fitting and single-segment fitting. Measurement of model performance adopted adjusted goodness of fit that combines sum of squred residuals and relative errors. Both model simulation and performance evalation utilized self-developed algorithms programed using C# languade and MS Visual Studio 2008. For models built upon full age-span data, predicted age-specific cancer incidence rates fitted very well with observed values for most (except cervical and breast) cancers with estimated goodness of fit (Rs) being over 0.96. When a given cancer is concerned, the R valuae of the logistic growth model derived using observed data from urban residents was greater than or at least equal to that of the same model built on data from rural people. For models based on multiple-5-year-segment data, the Rs remained fairly high (over 0.89) until 3-fourths of the data segments were excluded. For models using a fixed length single-segment of observed data, the older the age covered by the corresponding

  11. From Mindless Masses to Small Groups: Conceptualizing Collective Behavior in Crowd Modeling

    PubMed Central

    2015-01-01

    Computer simulations are increasingly used to monitor and predict behavior at large crowd events, such as mass gatherings, festivals and evacuations. We critically examine the crowd modeling literature and call for future simulations of crowd behavior to be based more closely on findings from current social psychological research. A systematic review was conducted on the crowd modeling literature (N = 140 articles) to identify the assumptions about crowd behavior that modelers use in their simulations. Articles were coded according to the way in which crowd structure was modeled. It was found that 2 broad types are used: mass approaches and small group approaches. However, neither the mass nor the small group approaches can accurately simulate the large collective behavior that has been found in extensive empirical research on crowd events. We argue that to model crowd behavior realistically, simulations must use methods which allow crowd members to identify with each other, as suggested by self-categorization theory. PMID:26388685

  12. Collective Flocking Dynamics: Long Rang Order in a Non-Equilibrium 2D XY Model

    NASA Astrophysics Data System (ADS)

    Tu, Yuhai

    1996-03-01

    We propose and study a non-equilibrium continuum dynamical model for the collective motion of large groups of biological organisms (e.g., flocks of birds, slime molds, schools of fishs, etc.) (J. Toner and Y. Tu, Phys. Rev. Lett.), 75(23), 4326(1995) Our model becomes highly non-trivial, and different from the equilibrium model, for dmodel exhibits a broken continuous symmetry even in d=2. Our model describes a large universality class of microscopic rules, including those recently simulated by Vicsek et. al.( T. Vicsek et. al. , Phys. Rev. Lett.) 75, 1226(95).

  13. DEVA: An extensible ontology-based annotation model for visual document collections

    NASA Astrophysics Data System (ADS)

    Jelmini, Carlo; Marchand-Maillet, Stephane

    2003-01-01

    The description of visual documents is a fundamental aspect of any efficient information management system, but the process of manually annotating large collections of documents is tedious and far from being perfect. The need for a generic and extensible annotation model therefore arises. In this paper, we present DEVA, an open, generic and expressive multimedia annotation framework. DEVA is an extension of the Dublin Core specification. The model can represent the semantic content of any visual document. It is described in the ontology language DAML+OIL and can easily be extended with external specialized ontologies, adapting the vocabulary to the given application domain. In parallel, we present the Magritte annotation tool, which is an early prototype that validates the DEVA features. Magritte allows to manually annotating image collections. It is designed with a modular and extensible architecture, which enables the user to dynamically adapt the user interface to specialized ontologies merged into DEVA.

  14. A Relational Model of the Financial Data Collected from Local Education Agencies by a State Department of Education.

    ERIC Educational Resources Information Center

    Mills, Richard P.

    The educational community is recognizing that it has had little direct control over or knowledge of educational data collection. The objective of this paper is to present a description of presently collected financial data collected by a state education department. An entity set model is used to create a relational view of the data to facilitate…

  15. Models of population-based analyses for data collected from large extended families

    PubMed Central

    Lee, Elisa T.; Howard, Barbara V.; Fabsitz, Richard R.; Devereux, Richard B.; MacCluer, Jean W.; Laston, Sandra; Comuzzie, Anthony G.; Shara, Nawar M.; Welty, Thomas K.

    2014-01-01

    Large studies of extended families usually collect valuable phenotypic data that may have scientific value for purposes other than testing genetic hypotheses if the families were not selected in a biased manner. These purposes include assessing population-based associations of diseases with risk factors/covariates and estimating population characteristics such as disease prevalence and incidence. Relatedness among participants however, violates the traditional assumption of independent observations in these classic analyses. The commonly used adjustment method for relatedness in population-based analyses is to use marginal models, in which clusters (families) are assumed to be independent (unrelated) with a simple and identical covariance (family) structure such as those called independent, exchangeable and unstructured covariance structures. However, using these simple covariance structures may not be optimally appropriate for outcomes collected from large extended families, and may under- or over-estimate the variances of estimators and thus lead to uncertainty in inferences. Moreover, the assumption that families are unrelated with an identical family structure in a marginal model may not be satisfied for family studies with large extended families. The aim of this paper is to propose models incorporating marginal models approaches with a covariance structure for assessing population-based associations of diseases with their risk factors/covariates and estimating population characteristics for epidemiological studies while adjusting for the complicated relatedness among outcomes (continuous/categorical, normally/non-normally distributed) collected from large extended families. We also discuss theoretical issues of the proposed models and show that the proposed models and covariance structure are appropriate for and capable of achieving the aim. PMID:20882324

  16. Unified description of 0+ states in a large class of nuclear collective models.

    PubMed

    Bonatsos, Dennis; McCutchan, E A; Casten, R F

    2008-07-11

    A remarkably simple regularity in the energies of 0+ states in a broad class of collective models is discussed. A single formula for all 0+ states in flat-bottomed infinite potentials that depends only on the number of dimensions and a simpler expression applicable to all three interacting boson approximation symmetries in the large N(B) limit are presented. Finally, a connection between the energy expression for 0+ states given by the X5 model and the predictions of the interacting boson approximation near the critical point of the first order phase transition is explored. PMID:18764176

  17. Quantifying uncertainty in parameter estimates for stochastic models of collective cell spreading using approximate Bayesian computation.

    PubMed

    Vo, Brenda N; Drovandi, Christopher C; Pettitt, Anthony N; Simpson, Matthew J

    2015-05-01

    Wound healing and tumour growth involve collective cell spreading, which is driven by individual motility and proliferation events within a population of cells. Mathematical models are often used to interpret experimental data and to estimate the parameters so that predictions can be made. Existing methods for parameter estimation typically assume that these parameters are constants and often ignore any uncertainty in the estimated values. We use approximate Bayesian computation (ABC) to estimate the cell diffusivity, D, and the cell proliferation rate, λ, from a discrete model of collective cell spreading, and we quantify the uncertainty associated with these estimates using Bayesian inference. We use a detailed experimental data set describing the collective cell spreading of 3T3 fibroblast cells. The ABC analysis is conducted for different combinations of initial cell densities and experimental times in two separate scenarios: (i) where collective cell spreading is driven by cell motility alone, and (ii) where collective cell spreading is driven by combined cell motility and cell proliferation. We find that D can be estimated precisely, with a small coefficient of variation (CV) of 2-6%. Our results indicate that D appears to depend on the experimental time, which is a feature that has been previously overlooked. Assuming that the values of D are the same in both experimental scenarios, we use the information about D from the first experimental scenario to obtain reasonably precise estimates of λ, with a CV between 4 and 12%. Our estimates of D and λ are consistent with previously reported values; however, our method is based on a straightforward measurement of the position of the leading edge whereas previous approaches have involved expensive cell counting techniques. Additional insights gained using a fully Bayesian approach justify the computational cost, especially since it allows us to accommodate information from different experiments in a principled

  18. An evaluation of 1D loss model collections for the off-design performance prediction of automotive turbocharger compressors

    NASA Astrophysics Data System (ADS)

    Harley, P.; Spence, S.; Early, J.; Filsinger, D.; Dietrich, M.

    2013-12-01

    Single-zone modelling is used to assess different collections of impeller 1D loss models. Three collections of loss models have been identified in literature, and the background to each of these collections is discussed. Each collection is evaluated using three modern automotive turbocharger style centrifugal compressors; comparisons of performance for each of the collections are made. An empirical data set taken from standard hot gas stand tests for each turbocharger is used as a baseline for comparison. Compressor range is predicted in this study; impeller diffusion ratio is shown to be a useful method of predicting compressor surge in 1D, and choke is predicted using basic compressible flow theory. The compressor designer can use this as a guide to identify the most compatible collection of losses for turbocharger compressor design applications. The analysis indicates the most appropriate collection for the design of automotive turbocharger centrifugal compressors.

  19. A stochastic vision-based model inspired by zebrafish collective behaviour in heterogeneous environments

    PubMed Central

    Collignon, Bertrand; Séguret, Axel; Halloy, José

    2016-01-01

    Collective motion is one of the most ubiquitous behaviours displayed by social organisms and has led to the development of numerous models. Recent advances in the understanding of sensory system and information processing by animals impels one to revise classical assumptions made in decisional algorithms. In this context, we present a model describing the three-dimensional visual sensory system of fish that adjust their trajectory according to their perception field. Furthermore, we introduce a stochastic process based on a probability distribution function to move in targeted directions rather than on a summation of influential vectors as is classically assumed by most models. In parallel, we present experimental results of zebrafish (alone or in group of 10) swimming in both homogeneous and heterogeneous environments. We use these experimental data to set the parameter values of our model and show that this perception-based approach can simulate the collective motion of species showing cohesive behaviour in heterogeneous environments. Finally, we discuss the advances of this multilayer model and its possible outcomes in biological, physical and robotic sciences. PMID:26909173

  20. A stochastic vision-based model inspired by zebrafish collective behaviour in heterogeneous environments.

    PubMed

    Collignon, Bertrand; Séguret, Axel; Halloy, José

    2016-01-01

    Collective motion is one of the most ubiquitous behaviours displayed by social organisms and has led to the development of numerous models. Recent advances in the understanding of sensory system and information processing by animals impels one to revise classical assumptions made in decisional algorithms. In this context, we present a model describing the three-dimensional visual sensory system of fish that adjust their trajectory according to their perception field. Furthermore, we introduce a stochastic process based on a probability distribution function to move in targeted directions rather than on a summation of influential vectors as is classically assumed by most models. In parallel, we present experimental results of zebrafish (alone or in group of 10) swimming in both homogeneous and heterogeneous environments. We use these experimental data to set the parameter values of our model and show that this perception-based approach can simulate the collective motion of species showing cohesive behaviour in heterogeneous environments. Finally, we discuss the advances of this multilayer model and its possible outcomes in biological, physical and robotic sciences. PMID:26909173

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

    PubMed Central

    Valero, Enrique; Adán, Antonio; Cerrada, Carlos

    2012-01-01

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

  2. Ground water flow modeling with sensitivity analyses to guide field data collection in a mountain watershed

    USGS Publications Warehouse

    Johnson, Raymond H.

    2007-01-01

    In mountain watersheds, the increased demand for clean water resources has led to an increased need for an understanding of ground water flow in alpine settings. In Prospect Gulch, located in southwestern Colorado, understanding the ground water flow system is an important first step in addressing metal loads from acid-mine drainage and acid-rock drainage in an area with historical mining. Ground water flow modeling with sensitivity analyses are presented as a general tool to guide future field data collection, which is applicable to any ground water study, including mountain watersheds. For a series of conceptual models, the observation and sensitivity capabilities of MODFLOW-2000 are used to determine composite scaled sensitivities, dimensionless scaled sensitivities, and 1% scaled sensitivity maps of hydraulic head. These sensitivities determine the most important input parameter(s) along with the location of observation data that are most useful for future model calibration. The results are generally independent of the conceptual model and indicate recharge in a high-elevation recharge zone as the most important parameter, followed by the hydraulic conductivities in all layers and recharge in the next lower-elevation zone. The most important observation data in determining these parameters are hydraulic heads at high elevations, with a depth of less than 100 m being adequate. Evaluation of a possible geologic structure with a different hydraulic conductivity than the surrounding bedrock indicates that ground water discharge to individual stream reaches has the potential to identify some of these structures. Results of these sensitivity analyses can be used to prioritize data collection in an effort to reduce time and money spend by collecting the most relevant model calibration data.

  3. From behavioural analyses to models of collective motion in fish schools

    PubMed Central

    Lopez, Ugo; Gautrais, Jacques; Couzin, Iain D.; Theraulaz, Guy

    2012-01-01

    Fish schooling is a phenomenon of long-lasting interest in ethology and ecology, widely spread across taxa and ecological contexts, and has attracted much interest from statistical physics and theoretical biology as a case of self-organized behaviour. One topic of intense interest is the search of specific behavioural mechanisms at stake at the individual level and from which the school properties emerges. This is fundamental for understanding how selective pressure acting at the individual level promotes adaptive properties of schools and in trying to disambiguate functional properties from non-adaptive epiphenomena. Decades of studies on collective motion by means of individual-based modelling have allowed a qualitative understanding of the self-organization processes leading to collective properties at school level, and provided an insight into the behavioural mechanisms that result in coordinated motion. Here, we emphasize a set of paradigmatic modelling assumptions whose validity remains unclear, both from a behavioural point of view and in terms of quantitative agreement between model outcome and empirical data. We advocate for a specific and biologically oriented re-examination of these assumptions through experimental-based behavioural analysis and modelling. PMID:24312723

  4. Simulating Flying Insects Using Dynamics and Data-Driven Noise Modeling to Generate Diverse Collective Behaviors.

    PubMed

    Ren, Jiaping; Wang, Xinjie; Jin, Xiaogang; Manocha, Dinesh

    2016-01-01

    We present a biologically plausible dynamics model to simulate swarms of flying insects. Our formulation, which is based on biological conclusions and experimental observations, is designed to simulate large insect swarms of varying densities. We use a force-based model that captures different interactions between the insects and the environment and computes collision-free trajectories for each individual insect. Furthermore, we model the noise as a constructive force at the collective level and present a technique to generate noise-induced insect movements in a large swarm that are similar to those observed in real-world trajectories. We use a data-driven formulation that is based on pre-recorded insect trajectories. We also present a novel evaluation metric and a statistical validation approach that takes into account various characteristics of insect motions. In practice, the combination of Curl noise function with our dynamics model is used to generate realistic swarm simulations and emergent behaviors. We highlight its performance for simulating large flying swarms of midges, fruit fly, locusts and moths and demonstrate many collective behaviors, including aggregation, migration, phase transition, and escape responses. PMID:27187068

  5. Simulating Flying Insects Using Dynamics and Data-Driven Noise Modeling to Generate Diverse Collective Behaviors

    PubMed Central

    Ren, Jiaping; Wang, Xinjie; Manocha, Dinesh

    2016-01-01

    We present a biologically plausible dynamics model to simulate swarms of flying insects. Our formulation, which is based on biological conclusions and experimental observations, is designed to simulate large insect swarms of varying densities. We use a force-based model that captures different interactions between the insects and the environment and computes collision-free trajectories for each individual insect. Furthermore, we model the noise as a constructive force at the collective level and present a technique to generate noise-induced insect movements in a large swarm that are similar to those observed in real-world trajectories. We use a data-driven formulation that is based on pre-recorded insect trajectories. We also present a novel evaluation metric and a statistical validation approach that takes into account various characteristics of insect motions. In practice, the combination of Curl noise function with our dynamics model is used to generate realistic swarm simulations and emergent behaviors. We highlight its performance for simulating large flying swarms of midges, fruit fly, locusts and moths and demonstrate many collective behaviors, including aggregation, migration, phase transition, and escape responses. PMID:27187068

  6. Protocols for vaginal inoculation and sample collection in the experimental mouse model of Candida vaginitis.

    PubMed

    Yano, Junko; Fidel, Paul L

    2011-01-01

    Vulvovaginal candidiasis (VVC), caused by Candida species, is a fungal infection of the lower female genital tract that affects approximately 75% of otherwise healthy women during their reproductive years. Predisposing factors include antibiotic usage, uncontrolled diabetes and disturbance in reproductive hormone levels due to pregnancy, oral contraceptives or hormone replacement therapies. Recurrent VVC (RVVC), defined as three or more episodes per year, affects a separate 5 to 8% of women with no predisposing factors. An experimental mouse model of VVC has been established and used to study the pathogenesis and mucosal host response to Candida. This model has also been employed to test potential antifungal therapies in vivo. The model requires that the animals be maintained in a state of pseudoestrus for optimal Candida colonization/infection. Under such conditions, inoculated animals will have detectable vaginal fungal burden for weeks to months. Past studies show an extremely high parallel between the animal model and human infection relative to immunological and physiological properties. Differences, however, include a lack of Candida as normal vaginal flora and a neutral vaginal pH in the mice. Here, we demonstrate a series of key methods in the mouse vaginitis model that include vaginal inoculation, rapid collection of vaginal specimens, assessment of vaginal fungal burden, and tissue preparations for cellular extraction/isolation. This is followed by representative results for constituents of vaginal lavage fluid, fungal burden, and draining lymph node leukocyte yields. With the use of anesthetics, lavage samples can be collected at multiple time points on the same mice for longitudinal evaluation of infection/colonization. Furthermore, this model requires no immunosuppressive agents to initiate infection, allowing immunological studies under defined host conditions. Finally, the model and each technique introduced here could potentially give rise to use of

  7. Recasting Janis's Groupthink Model: The Key Role of Collective Efficacy in Decision Fiascoes.

    PubMed

    Whyte

    1998-02-01

    This paper advances an explanation for decision fiascoes that reflects recent theoretical trends and was developed in response to a growing body of research that has failed to substantiate the groupthink model (Janis, 1982). In this new framework, the lack of vigilance and preference for risk that characterizes groups contaminated by groupthink are attributed in large part to perceptions of collective efficacy that unduly exceed capability. High collective efficacy may also contribute to the negative framing of decisions and to certain administrative and structural organizational faults. In the making of critical decisions, these factors induce a preference for risk and a powerful concurrence seeking tendency that, facilitated by group polarization, crystallize around a decision option that is likely to fail. Implications for research and some evidence in support of this approach to the groupthink phenomenon are also discussed. Copyright 1998 Academic Press. PMID:9705802

  8. A microscopic derivation of nuclear collective rotation-vibration model and its application to nuclei

    NASA Astrophysics Data System (ADS)

    Gulshani, P.

    2016-07-01

    We derive a microscopic version of the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for collective rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude. The nuclear Schrodinger equation is canonically transformed to collective co-ordinates, which is then linearized using a constrained variational method. The associated constraints are imposed on the wavefunction rather than on the particle co-ordinates. The approach yields three self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. For harmonic oscillator mean-field potentials, these equations are solved in closed forms for excitation energy, cut-off angular momentum, and other nuclear properties for the ground-state rotational band in some deformed nuclei. The results are compared with measured data.

  9. Collective behavior of asperities as a model for friction and adhesion

    NASA Astrophysics Data System (ADS)

    Hulikal, Srivatsan

    Understanding friction and adhesion in static and sliding contact of surfaces is important in numerous physical phenomena and technological applications. Most surfaces are rough at the microscale, and thus the real area of contact is only a fraction of the nominal area. The macroscopic frictional and adhesive response is determined by the collective behavior of the population of evolving and interacting microscopic contacts. This collective behavior can be very different from the behavior of individual contacts. It is thus important to understand how the macroscopic response emerges from the microscopic one. In this thesis, we develop a theoretical and computational framework to study the collective behavior. Our philosophy is to assume a simple behavior of a single asperity and study the collective response of an ensemble. Our work bridges the existing well-developed studies of single asperities with phenomenological laws that describe macroscopic rate-and-state behavior of frictional interfaces. We find that many aspects of the macroscopic behavior are robust with respect to the microscopic response. This explains why qualitatively similar frictional features are seen for a diverse range of materials. We first show that the collective response of an ensemble of one-dimensional independent viscoelastic elements interacting through a mean field reproduces many qualitative features of static and sliding friction evolution. The resulting macroscopic behavior is different from the microscopic one: for example, even if each contact is velocity-strengthening, the macroscopic behavior can be velocity-weakening. The framework is then extended to incorporate three-dimensional rough surfaces, long- range elastic interactions between contacts, and time-dependent material behaviors such as viscoelasticity and viscoplasticity. Interestingly, the mean field behavior dominates and the elastic interactions, though important from a quantitative perspective, do not change the

  10. A standardized technique for efficient platelet and leukocyte collection using the Model 30 Blood Processor.

    PubMed

    Aisner, J; Schiffer, C A; Wolff, J H; Wiernik, P H

    1976-01-01

    The Model 30 Blood Processor is a safe and simple means of harvesting blood cell components. Presently cell collection depends on a visual assessment by the operator of the indistinct boundaries of cell fractions. To determine when each cell component could best be harvested, serial samples were taken from the output port at fixed intervals anf the results of counts and differentials were graphed and tabulated. Studies in normal donors were done using acid-citrate-dextrose (ACD), 2 per cent sodium citrate in 6 per cent hydroxyethyl starch (HES), or heparin as anticoagulants. There was considerable overlap between the latter part of the platelet band, the leukocyte band and the rising hematocrit with all three anticoagulants. Normally functional lymphocytes could be harvested efficiently (approximately 80%) using ACD or heparin. Platelets could be harvested from ACD very efficiently (approximately 90%). Granulocytes could not be harvested from ACD (less than 10%) since they were dispersed in the red blood cell (RBC) layer. Using HES, granulocytes could be harvested efficiently (approximately 70%) by extending collection into the RBC layer. Based on these data, a standard technique for cell collection has been devised. The flow rate is slowed to 20 ml/min and collection is carried 30 ml (90 seconds at a rate of 20 ml/min) for platelets. The RBC loss is approximately 6 to 8 and 2 to 3 ml/pass respectively. These studies indicate that the Model 30 is a highly efficient apparatus for blood cell separation, but the volume of blood processed is limited by the intermittent blood flow. PMID:62425

  11. The development of empirical models to evaluate energy use and energy cost in wastewater collection

    NASA Astrophysics Data System (ADS)

    Young, David Morgan

    This research introduces a unique data analysis method and develops empirical models to evaluate energy use and energy cost in wastewater collection systems using operational variables. From these models, several Best Management Processes (BMPs) are identified that should benefit utilities and positively impact the operation of existing infrastructure as well as the design of new infrastructure. Further, the conclusions generated herein display high transferability to certain manufacturing processes. Therefore, it is anticipated that these findings will also benefit pumping applications outside of the water sector. Wastewater treatment is often the single largest expense at the local government level. Not surprisingly, significant research effort has been expended on examining the energy used in wastewater treatment. However, the energy used in wastewater collection systems remains underexplored despite significant potential for energy savings. Estimates place potential energy savings as high as 60% within wastewater collection; which, if applied across the United States equates to the energy used by nearly 125,000 American homes. Employing three years of data from Renewable Water Resources (ReWa), the largest wastewater utility in the Upstate of South Carolina, this study aims to develop useful empirical equations that will allow utilities to efficiently evaluate the energy use and energy cost of its wastewater collection system. ReWa's participation was motivated, in part, by their recent adoption of the United States Environmental Protection Agency "Effective Utility Strategies" within which exists a focus on energy management. The study presented herein identifies two primary variables related to the energy use and cost associated with wastewater collection: Specific Energy (Es) and Specific Cost (Cs). These two variables were found to rely primarily on the volume pumped by the individual pump stations and exhibited similar power functions for the three year

  12. The simplest maximum entropy model for collective behavior in a neural network

    NASA Astrophysics Data System (ADS)

    Tkačik, Gašper; Marre, Olivier; Mora, Thierry; Amodei, Dario; Berry, Michael J., II; Bialek, William

    2013-03-01

    Recent work emphasizes that the maximum entropy principle provides a bridge between statistical mechanics models for collective behavior in neural networks and experiments on networks of real neurons. Most of this work has focused on capturing the measured correlations among pairs of neurons. Here we suggest an alternative, constructing models that are consistent with the distribution of global network activity, i.e. the probability that K out of N cells in the network generate action potentials in the same small time bin. The inverse problem that we need to solve in constructing the model is analytically tractable, and provides a natural ‘thermodynamics’ for the network in the limit of large N. We analyze the responses of neurons in a small patch of the retina to naturalistic stimuli, and find that the implied thermodynamics is very close to an unusual critical point, in which the entropy (in proper units) is exactly equal to the energy.

  13. A Mathematical Model of Collective Cell Migration in a Three-Dimensional, Heterogeneous Environment

    PubMed Central

    Stonko, David P.; Manning, Lathiena; Starz-Gaiano, Michelle; Peercy, Bradford E.

    2015-01-01

    Cell migration is essential in animal development, homeostasis, and disease progression, but many questions remain unanswered about how this process is controlled. While many kinds of individual cell movements have been characterized, less effort has been directed towards understanding how clusters of cells migrate collectively through heterogeneous, cellular environments. To explore this, we have focused on the migration of the border cells during Drosophila egg development. In this case, a cluster of different cell types coalesce and traverse as a group between large cells, called nurse cells, in the center of the egg chamber. We have developed a new model for this collective cell migration based on the forces of adhesion, repulsion, migration and stochastic fluctuation to generate the movement of discrete cells. We implement the model using Identical Math Cells, or IMCs. IMCs can each represent one biological cell of the system, or can be aggregated using increased adhesion forces to model the dynamics of larger biological cells. The domain of interest is filled with IMCs, each assigned specific biophysical properties to mimic a diversity of cell types. Using this system, we have successfully simulated the migration of the border cell cluster through an environment filled with larger cells, which represent nurse cells. Interestingly, our simulations suggest that the forces utilized in this model are sufficient to produce behaviors of the cluster that are observed in vivo, such as rotation. Our framework was developed to capture a heterogeneous cell population, and our implementation strategy allows for diverse, but precise, initial position specification over a three- dimensional domain. Therefore, we believe that this model will be useful for not only examining aspects of Drosophila oogenesis, but also for modeling other two or three-dimensional systems that have multiple cell types and where investigating the forces between cells is of interest. PMID:25875645

  14. Modeling the Emergence of Modular Leadership Hierarchy During the Collective Motion of Herds Made of Harems

    NASA Astrophysics Data System (ADS)

    Ozogány, Katalin; Vicsek, Tamás

    2015-02-01

    Gregarious animals need to make collective decisions in order to keep their cohesiveness. Several species of them live in multilevel societies, and form herds composed of smaller communities. We present a model for the development of a leadership hierarchy in a herd consisting of loosely connected sub-groups (e.g. harems) by combining self organization and social dynamics. It starts from unfamiliar individuals without relationships and reproduces the emergence of a hierarchical and modular leadership network that promotes an effective spreading of the decisions from more capable individuals to the others, and thus gives rise to a beneficial collective decision. Our results stemming from the model are in a good agreement with our observations of a Przewalski horse herd (Hortobágy, Hungary). We find that the harem-leader to harem-member ratio observed in Przewalski horses corresponds to an optimal network in this approach regarding common success, and that the observed and modeled harem size distributions are close to a lognormal.

  15. Crises and Collective Socio-Economic Phenomena: Simple Models and Challenges

    NASA Astrophysics Data System (ADS)

    Bouchaud, Jean-Philippe

    2013-05-01

    Financial and economic history is strewn with bubbles and crashes, booms and busts, crises and upheavals of all sorts. Understanding the origin of these events is arguably one of the most important problems in economic theory. In this paper, we review recent efforts to include heterogeneities and interactions in models of decision. We argue that the so-called Random Field Ising model ( rfim) provides a unifying framework to account for many collective socio-economic phenomena that lead to sudden ruptures and crises. We discuss different models that can capture potentially destabilizing self-referential feedback loops, induced either by herding, i.e. reference to peers, or trending, i.e. reference to the past, and that account for some of the phenomenology missing in the standard models. We discuss some empirically testable predictions of these models, for example robust signatures of rfim-like herding effects, or the logarithmic decay of spatial correlations of voting patterns. One of the most striking result, inspired by statistical physics methods, is that Adam Smith's invisible hand can fail badly at solving simple coordination problems. We also insist on the issue of time-scales, that can be extremely long in some cases, and prevent socially optimal equilibria from being reached. As a theoretical challenge, the study of so-called "detailed-balance" violating decision rules is needed to decide whether conclusions based on current models (that all assume detailed-balance) are indeed robust and generic.

  16. Self-Organized Criticality in a Model of Collective Bank Bankruptcies

    NASA Astrophysics Data System (ADS)

    Aleksiejuk, Agata; HoŁyst, Janusz A.; Kossinets, Gueorgi

    The question we address here is of whether phenomena of collective bankruptcies are related to self-organized criticality. In order to answer it we propose a simple model of banking networks based on the random directed percolation. We study effects of one bank failure on the nucleation of contagion phase in a financial market. We recognize the power law distribution of contagion sizes in 3d- and 4d-networks as an indicator of SOC behavior. The SOC dynamics was not detected in 2d-lattices. The difference between 2d- and 3d- or 4d-systems is explained due to the percolation theory.

  17. Collective states of odd nuclei in a model with quadrupole-octupole degrees of freedom

    SciTech Connect

    Minkov, N. Drenska, S. B.; Yotov, P.; Bonatsos, D. Scheid, W.

    2007-08-15

    We apply the collective axial quadrupole-octupole Hamiltonian to describe the rotation-vibration motion of odd nuclei with Coriolis coupling between the even-even core and the unpaired nucleon.We consider that the core oscillates coherently with respect to the quadrupole and octupole axialdeformation variables. The coupling between the core and the unpaired nucleon provides a split paritydoublet structure of the spectrum. The formalism successfully reproduces the parity-doublet splitting in a wide range of odd-A nuclei. It provides model estimations for the third angular-momentum projection K on the intrinsic symmetry axis and the related intrinsic nuclear structure.

  18. Gamma emission in precompound reactions: 1, Statistical model and collective gamma decay

    SciTech Connect

    Hoering, A. Washington Univ., Seattle, WA . Inst. for Nuclear Theory); Weidenmueller, H.A. )

    1992-01-01

    We extend the theory of particle-induced precompound reactions by including gamma decay. We use the Brink-Axel hypothesis and consider the gamma emission of giant dipole resonances built on the ground state and on the excited states of the composite system. The latter are modeled as multiparticle multi-hole excitations. In this way, we combine the statistical ansatz and the chaining hypothesis typical for precompound reaction theories, with the collective aspects of gamma decay. Formulas for average S-matrix and average cross section are derived in this framework.

  19. Gamma emission in precompound reactions: 1, Statistical model and collective gamma decay

    SciTech Connect

    Hoering, A. |; Weidenmueller, H.A.

    1992-09-01

    We extend the theory of particle-induced precompound reactions by including gamma decay. We use the Brink-Axel hypothesis and consider the gamma emission of giant dipole resonances built on the ground state and on the excited states of the composite system. The latter are modeled as multiparticle multi-hole excitations. In this way, we combine the statistical ansatz and the chaining hypothesis typical for precompound reaction theories, with the collective aspects of gamma decay. Formulas for average S-matrix and average cross section are derived in this framework.

  20. Emergence of Collective Motion in a Model of Interacting Brownian Particles.

    PubMed

    Dossetti, Victor; Sevilla, Francisco J

    2015-07-31

    By studying a system of Brownian particles that interact among themselves only through a local velocity-alignment force that does not affect their speed, we show that self-propulsion is not a necessary feature for the flocking transition to take place as long as underdamped particle dynamics can be guaranteed. Moreover, the system transits from stationary phases close to thermal equilibrium, with no net flux of particles, to far-from-equilibrium ones exhibiting collective motion, phase coexistence, long-range order, and giant number fluctuations, features typically associated with ordered phases of models where self-propelled particles with overdamped dynamics are considered. PMID:26274444

  1. Emergence of Collective Motion in a Model of Interacting Brownian Particles

    NASA Astrophysics Data System (ADS)

    Dossetti, Victor; Sevilla, Francisco J.

    2015-07-01

    By studying a system of Brownian particles that interact among themselves only through a local velocity-alignment force that does not affect their speed, we show that self-propulsion is not a necessary feature for the flocking transition to take place as long as underdamped particle dynamics can be guaranteed. Moreover, the system transits from stationary phases close to thermal equilibrium, with no net flux of particles, to far-from-equilibrium ones exhibiting collective motion, phase coexistence, long-range order, and giant number fluctuations, features typically associated with ordered phases of models where self-propelled particles with overdamped dynamics are considered.

  2. Collective response to perturbations in a data-driven fish school model

    PubMed Central

    Calovi, Daniel S.; Lopez, Ugo; Schuhmacher, Paul; Chaté, Hugues; Sire, Clément; Theraulaz, Guy

    2015-01-01

    Fish schools are able to display a rich variety of collective states and behavioural responses when they are confronted by threats. However, a school's response to perturbations may be different depending on the nature of its collective state. Here we use a previously developed data-driven fish school model to investigate how the school responds to perturbations depending on its different collective states, we measure its susceptibility to such perturbations, and exploit its relation with the intrinsic fluctuations in the school. In particular, we study how a single or a small number of perturbing individuals whose attraction and alignment parameters are different from those of the main population affect the long-term behaviour of a school. We find that the responsiveness of the school to the perturbations is maximum near the transition region between milling and schooling states where the school exhibits multistability and regularly shifts between these two states. It is also in this region that the susceptibility, and hence the fluctuations, of the polarization order parameter is maximal. We also find that a significant school's response to a perturbation only happens below a certain threshold of the noise to social interactions ratio. PMID:25631571

  3. Optimizing Numerical Modeling and Field Data Collection in an Interdisciplinary Study of Upper Klamath Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Cheng, R. T.; Wood, T. M.; Gartner, J. W.

    2005-12-01

    collection network for the summer 2005 field season. Up to five wind anemometers have been installed around the lake to define the spatial variability of the wind field, and five ADCPs have been deployed in the lake to capture essential circulation features. The water quality monitoring network has been extended to cover the entire UKL, and monitoring stations have been placed at locations that will optimize the observation of important temporal and spatial variability in water quality as indicated by the circulation patterns predicted by the numerical model. The 2005 field data set will be used to refine the numerical hydrodynamic model upon which water quality modeling modules will be built. This case study demonstrated the use of field data to support numerical model implementation, and then the use of the numerical model results to improve the next cycle of field data collection. This loop optimizes the implementation of the numerical model and the effectiveness of field data collection.

  4. Critical Comparison of Information Models used by US Water Data Collection Agencies and Projects

    NASA Astrophysics Data System (ADS)

    Valentine, D. W.; Zaslavsky, I.; Whitenack, T.

    2009-12-01

    The CUAHSI Hydrologic Information System (HIS) project has been working to simply access to repositories of hydrologic information by developing information models, and data exchange standards. We are presently working with international community through the Open GIS Consortium to create standard that uses hydrologic semantics to communicate time series. As part of the process to create a water data exchange language, we reviewed the information structures that are presently being used by several agencies to define the requirements of the data model. In the US, federal agencies, the USGS and US EPA, collect and distribute information that is utilized by scientists in the hydrologic sciences. We determined that there are two orthogonal information sets utilized; observation data, such as stream gauge and temperature data, and water quality data, such as analytical chemistry analyses. While the data values can be represented in a time series in a common manner, the process used to collect and manage the information represent separate information sets. For continuous observations an organization manages information single point location, are managed as a set of data streams from instruments that produce a set of observations that are processed into a set of public data. For analytical data, and organization collects information as part of a project, which has a set of collection locations; at each location, a set of methods is used to collect samples, which are analyzed to produce water quality information. While the details of the observations between the two information sets differ, a common set of information can be conveyed as a time series. The CUAHSI Observations Data Model (ODM), a core set of information can be represented as “data value”: variable, location, date & time, value, units, quality control level (QCL), source, and method. The ODM also included optional attributes that are associated with a data value such as qualifier, accuracy, sample medium

  5. A data collection scheme for identification of parameters in a driver model

    NASA Technical Reports Server (NTRS)

    Mooring, B. W.; Mcdermott, M.; Su, J. M.

    1981-01-01

    A high gain steering controller to compensate for limitations in a handicapped driver's range of motion is employed when adapting vehicle to his use. A driver/vehicle system can become unstable as vehicle speed is increased, therefore it is desirable to use a computer simulation of the driver/vehicle combination as a design tool to investigate the system response prior to construction of a controller and road testing. Unknown driver parameters must be identified prior to use of the model for system analysis. A means to collect the data necessary for identification of these driver model parameters without extensive instrumentation of a vehicle to measure and record vehicle states is addressed. Initial tests of the procedure identified all of the driver parameters with errors of 6% or less.

  6. Activated sludge rheology: a critical review on data collection and modelling.

    PubMed

    Ratkovich, N; Horn, W; Helmus, F P; Rosenberger, S; Naessens, W; Nopens, I; Bentzen, T R

    2013-02-01

    Rheological behaviour is an important fluid property that severely impacts its flow behaviour and many aspects related to this. In the case of activated sludge, the apparent viscosity has an influence on e.g. pumping, hydrodynamics, mass transfer rates, sludge-water separation (settling and filtration). It therefore is an important property related to process performance, including process economics. To account for this, rheological behaviour is being included in process design, necessitating its measurement. However, measurements and corresponding protocols in literature are quite diverse, leading to varying results and conclusions. In this paper, a vast amount of papers are critically reviewed with respect to this and important flaws are highlighted with respect to rheometer choice, rheometer settings and measurement protocol. The obtained rheograms from experimental efforts have frequently been used to build viscosity models. However, this is not that straightforward and a lot of errors can be detected with respect to good modelling practice, including fair model selection criteria, qualitative parameter estimations and proper model validation. These important steps are however recurrently violated, severely affecting the model reliability and predictive power. This is illustrated with several examples. In conclusion, dedicated research is required to improve the rheological measurements and the models derived from them. At this moment, there is no guidance with respect to proper rheological measurements. Moreover, the rheological models are not very trustworthy and remain very "black box". More insight in the physical background needs to be gained. A model-based approach with dedicated experimental data collection is the key to address this. PMID:23219387

  7. A computer code for calculations in the algebraic collective model of the atomic nucleus

    NASA Astrophysics Data System (ADS)

    Welsh, T. A.; Rowe, D. J.

    2016-03-01

    A Maple code is presented for algebraic collective model (ACM) calculations. The ACM is an algebraic version of the Bohr model of the atomic nucleus, in which all required matrix elements are derived by exploiting the model's SU(1 , 1) × SO(5) dynamical group. This paper reviews the mathematical formulation of the ACM, and serves as a manual for the code. The code enables a wide range of model Hamiltonians to be analysed. This range includes essentially all Hamiltonians that are rational functions of the model's quadrupole moments qˆM and are at most quadratic in the corresponding conjugate momenta πˆN (- 2 ≤ M , N ≤ 2). The code makes use of expressions for matrix elements derived elsewhere and newly derived matrix elements of the operators [ π ˆ ⊗ q ˆ ⊗ π ˆ ] 0 and [ π ˆ ⊗ π ˆ ] LM. The code is made efficient by use of an analytical expression for the needed SO(5)-reduced matrix elements, and use of SO(5) ⊃ SO(3)  Clebsch-Gordan coefficients obtained from precomputed data files provided with the code.

  8. Modeling the emergence of language as an embodied collective cognitive activity.

    PubMed

    Hutchins, Edwin; Johnson, Christine M

    2009-07-01

    Two decades of attempts to model the emergence of language as a collective cognitive activity have demonstrated a number of principles that might have been part of the historical process that led to language. Several models have demonstrated the emergence of structure in a symbolic medium, but none has demonstrated the emergence of the capacity for symbolic representation. The current shift in cognitive science toward theoretical frameworks based on embodiment is already furnishing computational models with additional mechanisms relevant to the emergence of symbolic language. An analysis of embodied interaction among captive, but not human-enculturated, bonobo chimpanzees reveals a number of additional features of embodiment that are relevant to the emergence of symbolic language, but that have not yet been explored in computational simulation models; for example, complementarity of action in addition to imitation, iconic in addition to indexical gesture, coordination among multiple sensory and perceptual modalities, and the orchestration of intra- and inter-individual motor coordination. The bonobos provide an evolutionarily plausible intermediate stage in the development of symbolic expression that can inform efforts to model the emergence of symbolic language. PMID:25164999

  9. Microgrooved Polymer Substrates Promote Collective Cell Migration To Accelerate Fracture Healing in an in Vitro Model.

    PubMed

    Zhang, Qing; Dong, Hua; Li, Yuli; Zhu, Ye; Zeng, Lei; Gao, Huichang; Yuan, Bo; Chen, Xiaofeng; Mao, Chuanbin

    2015-10-21

    Surface topography can affect cell adhesion, morphology, polarity, cytoskeleton organization, and osteogenesis. However, little is known about the effect of topography on the fracture healing in repairing nonunion and large bone defects. Microgrooved topography on the surface of bone implants may promote cell migration into the fracture gap to accelerate fracture healing. To prove this hypothesis, we used an in vitro fracture (wound) healing assay on the microgrooved polycaprolactone substrates to study the effect of microgroove widths and depths on the osteoblast-like cell (MG-63) migration and the subsequent healing. We found that the microgrooved substrates promoted MG-63 cells to migrate collectively into the wound gap, which serves as a fracture model, along the grooves and ridges as compared with the flat substrates. Moreover, the groove widths did not show obvious influence on the wound healing whereas the smaller groove depths tended to favor the collective cell migration and thus subsequent healing. The microgrooved substrates accelerated the wound healing by facilitating the collective cell migration into the wound gaps but not by promoting the cell proliferation. Furthermore, microgrooves were also found to promote the migration of human mesenchymal stem cells (hMSCs) to heal the fracture model. Though osteogenic differentiation of hMSCs was not improved on the microgrooved substrate, collagen I and minerals deposited by hMSCs were organized in a way similar to those in the extracellular matrix of natural bone. These findings suggest the necessity in using microgrooved implants in enhancing fracture healing in bone repair. PMID:26457873

  10. Artefact Mobile Data Model to Support Cultural Heritage Data Collection and Interpretation

    NASA Astrophysics Data System (ADS)

    Mohamed-Ghouse, Z. S.; Kelly, D.; Costello, A.; Edmonds, V.

    2012-07-01

    This paper discusses the limitation of existing data structures in mobile mapping applications to support archaeologists to manage the artefact (any object made or modified by a human culture, and later recovered by an archaeological endeavor) details excavated at a cultural heritage site. Current limitations of data structure in the mobile mapping application allow archeologist to record only one artefact per test pit location. In reality, more than one artefact can be excavated from the same test pit location. A spatial data model called Artefact Mobile Data Model (AMDM) was developed applying existing Relational Data Base Management System (RDBMS) technique to overcome the limitation. The data model was implemented in a mobile database environment called SprintDB Pro which was in turn connected to ArcPad 7.1 mobile mapping application through Open Data Base Connectivity (ODBC). In addition, the design of a user friendly application built on top of AMDM to interpret and record the technology associated with each artefact excavated in the field is also discussed in the paper. In summary, the paper discusses the design and implementation of a data model to facilitate the collection of artefacts in the field using integrated mobile mapping and database approach.

  11. Continuum Model of Collective Cell Migration in Wound Healing and Colony Expansion

    PubMed Central

    Arciero, Julia C.; Mi, Qi; Branca, Maria F.; Hackam, David J.; Swigon, David

    2011-01-01

    Collective cell migration plays an important role during wound healing and embryo development. Although the exact mechanisms that coordinate such migration are still unknown, experimental studies of moving cell layers have shown that the primary interactions governing the motion of the layer are the force of lamellipodia, the adhesion of cells to the substrate, and the adhesion of cells to each other. Here, we derive a two-dimensional continuum mechanical model of cell-layer migration that is based on a novel assumption of elastic deformation of the layer and incorporates basic mechanical interactions of cells as well as cell proliferation and apoptosis. The evolution equations are solved numerically using a level set method. The model successfully reproduces data from two types of experiments: 1), the contraction of an enterocyte cell layer during wound healing; and 2), the expansion of a radially symmetric colony of MDCK cells, both in the edge migration velocity and in cell-layer density. In accord with experimental observations, and in contrast to reaction-diffusion models, this model predicts a partial wound closure if lamellipod formation is inhibited at the wound edge and gives implications of the effect of spatially restricted proliferation. PMID:21281567

  12. Ottawa's urban forest: A geospatial approach to data collection for the UFORE/i-Tree Eco ecosystem services valuation model

    NASA Astrophysics Data System (ADS)

    Palmer, Michael D.

    The i-Tree Eco model, developed by the U.S. Forest Service, is commonly used to estimate the value of the urban forest and the ecosystem services trees provide. The model relies on field-based measurements to estimate ecosystem service values. However, the methods for collecting the field data required for the model can be extensive and costly for large areas, and data collection can thus be a barrier to implementing the model for many cities. This study investigated the use of geospatial technologies as a means to collect urban forest structure measurements within the City of Ottawa, Ontario. Results show that geospatial data collection methods can serve as a proxy for urban forest structure parameters required by i-Tree Eco. Valuations using the geospatial approach are shown to be less accurate than those developed from field-based data, but significantly less expensive. Planners must weigh the limitations of either approach when planning assessment projects.

  13. Distribution models for koalas in South Australia using citizen science-collected data

    PubMed Central

    Sequeira, Ana M M; Roetman, Philip E J; Daniels, Christopher B; Baker, Andrew K; Bradshaw, Corey J A

    2014-01-01

    The koala (Phascolarctos cinereus) occurs in the eucalypt forests of eastern and southern Australia and is currently threatened by habitat fragmentation, climate change, sexually transmitted diseases, and low genetic variability throughout most of its range. Using data collected during the Great Koala Count (a 1-day citizen science project in the state of South Australia), we developed generalized linear mixed-effects models to predict habitat suitability across South Australia accounting for potential errors associated with the dataset. We derived spatial environmental predictors for vegetation (based on dominant species of Eucalyptus or other vegetation), topographic water features, rain, elevation, and temperature range. We also included predictors accounting for human disturbance based on transport infrastructure (sealed and unsealed roads). We generated random pseudo-absences to account for the high prevalence bias typical of citizen-collected data. We accounted for biased sampling effort along sealed and unsealed roads by including an offset for distance to transport infrastructures. The model with the highest statistical support (wAICc ∼ 1) included all variables except rain, which was highly correlated with elevation. The same model also explained the highest deviance (61.6%), resulted in high R2(m) (76.4) and R2(c) (81.0), and had a good performance according to Cohen's κ (0.46). Cross-validation error was low (∼ 0.1). Temperature range, elevation, and rain were the best predictors of koala occurrence. Our models predict high habitat suitability in Kangaroo Island, along the Mount Lofty Ranges, and at the tips of the Eyre, Yorke and Fleurieu Peninsulas. In the highest-density region (5576 km2) of the Adelaide–Mount Lofty Ranges, a density–suitability relationship predicts a population of 113,704 (95% confidence interval: 27,685–199,723; average density = 5.0–35.8 km−2). We demonstrate the power of citizen science data for predicting species

  14. Distribution models for koalas in South Australia using citizen science-collected data.

    PubMed

    Sequeira, Ana M M; Roetman, Philip E J; Daniels, Christopher B; Baker, Andrew K; Bradshaw, Corey J A

    2014-06-01

    The koala (Phascolarctos cinereus) occurs in the eucalypt forests of eastern and southern Australia and is currently threatened by habitat fragmentation, climate change, sexually transmitted diseases, and low genetic variability throughout most of its range. Using data collected during the Great Koala Count (a 1-day citizen science project in the state of South Australia), we developed generalized linear mixed-effects models to predict habitat suitability across South Australia accounting for potential errors associated with the dataset. We derived spatial environmental predictors for vegetation (based on dominant species of Eucalyptus or other vegetation), topographic water features, rain, elevation, and temperature range. We also included predictors accounting for human disturbance based on transport infrastructure (sealed and unsealed roads). We generated random pseudo-absences to account for the high prevalence bias typical of citizen-collected data. We accounted for biased sampling effort along sealed and unsealed roads by including an offset for distance to transport infrastructures. The model with the highest statistical support (wAIC c ∼ 1) included all variables except rain, which was highly correlated with elevation. The same model also explained the highest deviance (61.6%), resulted in high R (2)(m) (76.4) and R (2)(c) (81.0), and had a good performance according to Cohen's κ (0.46). Cross-validation error was low (∼ 0.1). Temperature range, elevation, and rain were the best predictors of koala occurrence. Our models predict high habitat suitability in Kangaroo Island, along the Mount Lofty Ranges, and at the tips of the Eyre, Yorke and Fleurieu Peninsulas. In the highest-density region (5576 km(2)) of the Adelaide-Mount Lofty Ranges, a density-suitability relationship predicts a population of 113,704 (95% confidence interval: 27,685-199,723; average density = 5.0-35.8 km(-2)). We demonstrate the power of citizen science data for predicting species

  15. Study on collection efficiency of fission products by spray: Experimental device and modelling

    SciTech Connect

    Ducret, D.; Roblot, D.; Vendel, J.; Billarand, Y.

    1997-08-01

    Consequences of an hypothetical overheating reactor accident in nuclear power plants can be limited by spraying cold water drops into containment building. The spray reduces the pressure and the temperature levels by condensation of steam and leads to the washout of fission products (aerosols and gaseous iodine). The present study includes a large program devoted to the evaluation of realistic washout rates. An experimental device (named CARAIDAS) was designed and built in order to determine the collection efficiency of aerosols and iodine absorption by drops with representative conditions of post-accident atmosphere. This experimental device is presented in the paper and more particularly: (1) the experimental enclosure in which representative thermodynamic conditions can be achieved, (2) the monosized drops generator, the drops diameter measurement and the drops collector, (3) the cesium iodide aerosols generator and the aerosols measurements. Modelling of steam condensation on drops aerosols collection and iodine absorption are described. First experimental and code results on drops and aerosols behaviour are compared. 8 refs., 18 figs.

  16. Theory of a zone-boundary collective state in A1: A model calculation

    NASA Astrophysics Data System (ADS)

    Sturm, K.; Oliveira, L. E.

    1984-10-01

    A two-band model, which previously was used successfully to evaluate the optical absorption in A1, is applied to derive the k-->- and ω-dependent dielectric function ɛM(k-->,ω) for k--> parallel to the [100] direction with use of degenerate perturbation theory. Within the nearly-free-electron approximation, it is shown that a pair of (200) Bragg planes gives rise to another pole in the energy-loss function Im[-1ɛ] and hence to a collective mode. Both the dispersion of the mode throughout the first Brillouin zone and the strength of the mode are evaluated and are found to agree very well with electron-energy-loss spectroscopy data. A detailed discussion of the nature of this mode is given. The mode is of the same origin as the so-called zone-boundary collective state (ZBCS) first proposed by Foo and Hopfield in Na. Comparison is made with a numerical calculation of ɛM(k-->,ω) by Singhal for some discrete k--> values. The general importance of the ZBCS for the understanding of the energy-loss spectrum and for more complicated systems is pointed out.

  17. Cohesion, team mental models, and collective efficacy: towards an integrated framework of team dynamics in sport.

    PubMed

    Filho, Edson; Tenenbaum, Gershon; Yang, Yanyun

    2015-01-01

    A nomological network on team dynamics in sports consisting of a multiframework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMMs), collective efficacy (CE) and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMMs, CE and PPP. Results are congruent with the theoretical conceptualisation of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMMs and CE beliefs. TMMs and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams' season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined. PMID:25385557

  18. Charge collection efficiency degradation induced by MeV ions in semiconductor devices: Model and experiment

    NASA Astrophysics Data System (ADS)

    Vittone, E.; Pastuovic, Z.; Breese, M. B. H.; Garcia Lopez, J.; Jaksic, M.; Raisanen, J.; Siegele, R.; Simon, A.; Vizkelethy, G.

    2016-04-01

    This paper investigates both theoretically and experimentally the charge collection efficiency (CCE) degradation in silicon diodes induced by energetic ions. Ion Beam Induced Charge (IBIC) measurements carried out on n- and p-type silicon diodes which were previously irradiated with MeV He ions show evidence that the CCE degradation does not only depend on the mass, energy and fluence of the damaging ion, but also depends on the ion probe species and on the polarization state of the device. A general one-dimensional model is derived, which accounts for the ion-induced defect distribution, the ionization profile of the probing ion and the charge induction mechanism. Using the ionizing and non-ionizing energy loss profiles resulting from simulations based on the binary collision approximation and on the electrostatic/transport parameters of the diode under study as input, the model is able to accurately reproduce the experimental CCE degradation curves without introducing any phenomenological additional term or formula. Although limited to low level of damage, the model is quite general, including the displacement damage approach as a special case and can be applied to any semiconductor device. It provides a method to measure the capture coefficients of the radiation induced recombination centres. They can be considered indexes, which can contribute to assessing the relative radiation hardness of semiconductor materials.

  19. Charge collection efficiency degradation induced by MeV ions in semiconductor devices: Model and experiment

    DOE PAGESBeta

    Vittone, Ettore; Pastuovic, Zeljko; Breese, Mark B. H.; Lopez, Javier Garicia; Jaksic, Milko; Raisanen, Jyrki; Siegele, Rainer; Simon, Aliz; Vizkelethy, Gyorgy

    2016-02-08

    This study investigates both theoretically and experimentally the charge collection efficiency (CCE) degradation in silicon diodes induced by energetic ions. Ion Beam Induced Charge (IBIC) measurements carried out on n- and p-type silicon diodes which were previously irradiated with MeV He ions show evidence that the CCE degradation does not only depend on the mass, energy and fluence of the damaging ion, but also depends on the ion probe species and on the polarization state of the device. A general one-dimensional model is derived, which accounts for the ion-induced defect distribution, the ionization profile of the probing ion and themore » charge induction mechanism. Using the ionizing and non-ionizing energy loss profiles resulting from simulations based on the binary collision approximation and on the electrostatic/transport parameters of the diode under study as input, the model is able to accurately reproduce the experimental CCE degradation curves without introducing any phenomenological additional term or formula. Although limited to low level of damage, the model is quite general, including the displacement damage approach as a special case and can be applied to any semiconductor device. It provides a method to measure the capture coefficients of the radiation induced recombination centres. They can be considered indexes, which can contribute to assessing the relative radiation hardness of semiconductor materials.« less

  20. Geostatistical Modeling of Malaria Endemicity using Serological Indicators of Exposure Collected through School Surveys

    PubMed Central

    Ashton, Ruth A.; Kefyalew, Takele; Rand, Alison; Sime, Heven; Assefa, Ashenafi; Mekasha, Addis; Edosa, Wasihun; Tesfaye, Gezahegn; Cano, Jorge; Teka, Hiwot; Reithinger, Richard; Pullan, Rachel L.; Drakeley, Chris J.; Brooker, Simon J.

    2015-01-01

    Ethiopia has a diverse ecology and geography resulting in spatial and temporal variation in malaria transmission. Evidence-based strategies are thus needed to monitor transmission intensity and target interventions. A purposive selection of dried blood spots collected during cross-sectional school-based surveys in Oromia Regional State, Ethiopia, were tested for presence of antibodies against Plasmodium falciparum and P. vivax antigens. Spatially explicit binomial models of seroprevalence were created for each species using a Bayesian framework, and used to predict seroprevalence at 5 km resolution across Oromia. School seroprevalence showed a wider prevalence range than microscopy for both P. falciparum (0–50% versus 0–12.7%) and P. vivax (0–53.7% versus 0–4.5%), respectively. The P. falciparum model incorporated environmental predictors and spatial random effects, while P. vivax seroprevalence first-order trends were not adequately explained by environmental variables, and a spatial smoothing model was developed. This is the first demonstration of serological indicators being used to detect large-scale heterogeneity in malaria transmission using samples from cross-sectional school-based surveys. The findings support the incorporation of serological indicators into periodic large-scale surveillance such as Malaria Indicator Surveys, and with particular utility for low transmission and elimination settings. PMID:25962770

  1. Data Collection Handbook to Support Modeling Impacts of Radioactive Material in Soil and Building Structures

    SciTech Connect

    Yu, Charley; Kamboj, Sunita; Wang, Cheng; Cheng, Jing-Jy

    2015-09-01

    This handbook is an update of the 1993 version of the Data Collection Handbook and the Radionuclide Transfer Factors Report to support modeling the impact of radioactive material in soil. Many new parameters have been added to the RESRAD Family of Codes, and new measurement methodologies are available. A detailed review of available parameter databases was conducted in preparation of this new handbook. This handbook is a companion document to the user manuals when using the RESRAD (onsite) and RESRAD-OFFSITE code. It can also be used for RESRAD-BUILD code because some of the building-related parameters are included in this handbook. The RESRAD (onsite) has been developed for implementing U.S. Department of Energy Residual Radioactive Material Guidelines. Hydrogeological, meteorological, geochemical, geometrical (size, area, depth), crops and livestock, human intake, source characteristic, and building characteristic parameters are used in the RESRAD (onsite) code. The RESRAD-OFFSITE code is an extension of the RESRAD (onsite) code and can also model the transport of radionuclides to locations outside the footprint of the primary contamination. This handbook discusses parameter definitions, typical ranges, variations, and measurement methodologies. It also provides references for sources of additional information. Although this handbook was developed primarily to support the application of RESRAD Family of Codes, the discussions and values are valid for use of other pathway analysis models and codes.

  2. Multiscale Modelling and Analysis of Collective Decision Making in Swarm Robotics

    PubMed Central

    Vigelius, Matthias; Meyer, Bernd; Pascoe, Geoffrey

    2014-01-01

    We present a unified approach to describing certain types of collective decision making in swarm robotics that bridges from a microscopic individual-based description to aggregate properties. Our approach encompasses robot swarm experiments, microscopic and probabilistic macroscopic-discrete simulations as well as an analytic mathematical model. Following up on previous work, we identify the symmetry parameter, a measure of the progress of the swarm towards a decision, as a fundamental integrated swarm property and formulate its time evolution as a continuous-time Markov process. Contrary to previous work, which justified this approach only empirically and a posteriori, we justify it from first principles and derive hard limits on the parameter regime in which it is applicable. PMID:25369026

  3. Multiscale modelling and analysis of collective decision making in swarm robotics.

    PubMed

    Vigelius, Matthias; Meyer, Bernd; Pascoe, Geoffrey

    2014-01-01

    We present a unified approach to describing certain types of collective decision making in swarm robotics that bridges from a microscopic individual-based description to aggregate properties. Our approach encompasses robot swarm experiments, microscopic and probabilistic macroscopic-discrete simulations as well as an analytic mathematical model. Following up on previous work, we identify the symmetry parameter, a measure of the progress of the swarm towards a decision, as a fundamental integrated swarm property and formulate its time evolution as a continuous-time Markov process. Contrary to previous work, which justified this approach only empirically and a posteriori, we justify it from first principles and derive hard limits on the parameter regime in which it is applicable. PMID:25369026

  4. Border cell migration: a model system for live imaging and genetic analysis of collective cell movement.

    PubMed

    Prasad, Mohit; Wang, Xiaobo; He, Li; Montell, Denise J

    2011-01-01

    Border cell migration in the Drosophila ovary has emerged as a genetically tractable model for studying collective cell movement. Over many years border cell migration was exclusively studied in fixed samples due to the inability to culture stage 9 egg chambers in vitro. Although culturing late stage egg chambers was long feasible, stage 9 egg chambers survived only briefly outside the female body. We identified culture conditions that support stage 9 egg chamber development and sustain complete migration of border cells ex vivo. This protocol enables one to compare the dynamics of egg chamber development in wild type and mutant egg chambers using time-lapse microscopy and taking advantage of a multiposition microscope with a motorized imaging stage. In addition, this protocol has been successfully used in combination with fluorescence resonance energy transfer biosensors, photo-activatable proteins, and pharmacological agents and can be used with widefield or confocal microscopes in either an upright or inverted configuration. PMID:21748683

  5. Regression modeling of particle size distributions in urban storm water: advancements through improved sample collection methods

    USGS Publications Warehouse

    Fienen, Michael N.; Selbig, William R.

    2012-01-01

    A new sample collection system was developed to improve the representation of sediment entrained in urban storm water by integrating water quality samples from the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of suspended-sediment concentration and particle size distribution at three independent study locations. Use of the DISA decreased variability, which improved statistical regression to predict particle size distribution using surrogate environmental parameters, such as precipitation depth and intensity. The performance of this statistical modeling technique was compared to results using traditional fixed-point sampling methods and was found to perform better. When environmental parameters can be used to predict particle size distributions, environmental managers have more options when characterizing concentrations, loads, and particle size distributions in urban runoff.

  6. A model for improving student confidence and experience in diagnostic sample collection and interpretation.

    PubMed

    Williams, Laurel E; Nettifee-Osborne, Julie A; Johnson, Jeffrey L

    2006-01-01

    Confidence and proficiency in diagnosing and treating a variety of diseases is of obvious importance to veterinary students. Traditional teaching methods relying on live-animal laboratories or teaching-hospital cases may not provide the breadth and depth of experience necessary to promote optimal development of confidence and skills. These settings also raise concerns about expense, about animal welfare when animals are used in teaching laboratories, and about the stress and potential risks associated with client-owned pets in the teaching hospital. A one-week course implemented in our veterinary curriculum provides the opportunity for students to develop self-assurance and experience in sample collection and interpretation skills in a realistic, clinical-model setting. This course provides students with significantly improved levels of confidence when performing procedures and interpreting results from a variety of procedures and helps prepare them to become clinicians entering the practice of veterinary medicine. PMID:16767653

  7. A Semi-Classical, Microscopic Model for Nuclear Collective Rotation Plus RPA

    SciTech Connect

    Gulshani, P.

    2007-04-28

    Collective rotation and vibration of deformed nuclei are described semiclassically but microscopically by first transforming the time-dependent Schrodinger equation to a rotating frame, while preserving time-reversal invariance, and then applying a variational method. The rotating-frame axes are chosen to coincide with the principal axes of the expectation of an arbitrary, symmetric second-rank tensor operator {gamma}. It is shown that the equations derived for the rotational and vibrational motions decouple completely due to the rotational invariance of the Hamiltonian and diagonality of the expectation of {gamma} in the rotating frame. The equations describing the vibration reduce to those of the RPA. The equation describing the rotation generalizes that of the conventional cranking model (CM). The predicted rotation moment of inertia is shown to reduce to that of the CM for special types of particle interactions.

  8. Using a Communication Model to Collect Measurement Data through Mobile Devices

    PubMed Central

    Bravo, José; Villarreal, Vladimir; Hervás, Ramón; Urzaiz, Gabriel

    2012-01-01

    Wireless systems and services have undergone remarkable development since the first mobile phone system was introduced in the early 1980s. The use of sensors in an Ambient Intelligence approach is a great solution in a medical environment. We define a communication architecture to facilitate the information transfer between all connected devices. This model is based in layers to allow the collection of measurement data to be used in our framework monitoring architecture. An overlay-based solution is built between network elements in order to provide an efficient and highly functional communication platform that allows the connection of a wide variety of devices and technologies, and serves also to perform additional functions such as the possibility to perform some processing in the network that may help to improve overall performance. PMID:23012542

  9. Phase transition in the collective migration of tissue cells: Experiment and model

    NASA Astrophysics Data System (ADS)

    Szabó, B.; Szöllösi, G. J.; Gönci, B.; Jurányi, Zs.; Selmeczi, D.; Vicsek, Tamás

    2006-12-01

    We have recorded the swarming-like collective migration of a large number of keratocytes (tissue cells obtained from the scales of goldfish) using long-term videomicroscopy. By increasing the overall density of the migrating cells, we have been able to demonstrate experimentally a kinetic phase transition from a disordered into an ordered state. Near the critical density a complex picture emerges with interacting clusters of cells moving in groups. Motivated by these experiments we have constructed a flocking model that exhibits a continuous transition to the ordered phase, while assuming only short-range interactions and no explicit information about the knowledge of the directions of motion of neighbors. Placing cells in microfabricated arenas we found spectacular whirling behavior which we could also reproduce in simulations.

  10. Standardized data collection to build prediction models in oncology: a prototype for rectal cancer.

    PubMed

    Meldolesi, Elisa; van Soest, Johan; Damiani, Andrea; Dekker, Andre; Alitto, Anna Rita; Campitelli, Maura; Dinapoli, Nicola; Gatta, Roberto; Gambacorta, Maria Antonietta; Lanzotti, Vito; Lambin, Philippe; Valentini, Vincenzo

    2016-01-01

    The advances in diagnostic and treatment technology are responsible for a remarkable transformation in the internal medicine concept with the establishment of a new idea of personalized medicine. Inter- and intra-patient tumor heterogeneity and the clinical outcome and/or treatment's toxicity's complexity, justify the effort to develop predictive models from decision support systems. However, the number of evaluated variables coming from multiple disciplines: oncology, computer science, bioinformatics, statistics, genomics, imaging, among others could be very large thus making traditional statistical analysis difficult to exploit. Automated data-mining processes and machine learning approaches can be a solution to organize the massive amount of data, trying to unravel important interaction. The purpose of this paper is to describe the strategy to collect and analyze data properly for decision support and introduce the concept of an 'umbrella protocol' within the framework of 'rapid learning healthcare'. PMID:26674745

  11. Emergence of cluster structures and collectivity within a no-core shell-model framework

    NASA Astrophysics Data System (ADS)

    Launey, K. D.; Dreyfuss, A. C.; Draayer, J. P.; Dytrych, T.; Baker, R.

    2014-12-01

    An innovative symmetry-guided concept, which capitalizes on partial as well as exact symmetries that underpin the structure of nuclei, is discussed. Within this framework, ab initio applications of the theory to light nuclei reveal the origin of collective modes and the emergence a simple orderly pattern from first principles. This provides a strategy for determining the nature of bound states of nuclei in terms of a relatively small fraction of the complete shell-model space, which, in turn, can be used to explore ultra-large model spaces for a description of alpha-cluster and highly deformed structures together with the associated rotations. We find that by using only a fraction of the model space extended far beyond current no-core shell-model limits and a long-range interaction that respects the symmetries in play, the outcome reproduces characteristic features of the low-lying 0+ states in 12 C (including the elusive Hoyle state and its 2+ excitation) and agrees with ab initio results in smaller spaces. This is achieved by selecting those particle configurations and components of the interaction found to be foremost responsible for the primary physics governing clustering phenomena and large spatial deformation in the ground-state and Hoyle-state rotational bands of 12 C. For these states, we offer a novel perspective emerging out of no-core shell-model considerations, including a discussion of associated nuclear deformation, matter radii, and density distribution. The framework we find is also extensible to negative-parity states (e.g., the 3-1 state in 12C) and beyond, namely, to the low-lying 0+ states of 8Be as well as the ground-state rotational band of Ne, Mg, and Si isotopes. The findings inform key features of the nuclear interaction and point to a new insight into the formation of highly-organized simple patterns in nuclear dynamics.

  12. Collecting Protein Biomarkers in Breath Using Electret Filters: A Preliminary Method on New Technical Model and Human Study

    PubMed Central

    Li, Wang; Pi, Xitian; Qiao, Panpan; Liu, Hongying

    2016-01-01

    Biomarkers in exhaled breath are useful for respiratory disease diagnosis in human volunteers. Conventional methods that collect non-volatile biomarkers, however, necessitate an extensive dilution and sanitation processes that lowers collection efficiencies and convenience of use. Electret filter emerged in recent decade to collect virus biomarkers in exhaled breath given its simplicity and effectiveness. To investigate the capability of electret filters to collect protein biomarkers, a model that consists of an atomizer that produces protein aerosol and an electret filter that collects albumin and carcinoembryonic antigen-a typical biomarker in lung cancer development- from the atomizer is developed. A device using electret filter as the collecting medium is designed to collect human albumin from exhaled breath of 6 volunteers. Comparison of the collecting ability between the electret filter method and other 2 reported methods is finally performed based on the amounts of albumin collected from human exhaled breath. In conclusion, a decreasing collection efficiency ranging from 17.6% to 2.3% for atomized albumin aerosol and 42% to 12.5% for atomized carcinoembryonic antigen particles is found; moreover, an optimum volume of sampling human exhaled breath ranging from 100 L to 200 L is also observed; finally, the self-designed collecting device shows a significantly better performance in collecting albumin from human exhaled breath than the exhaled breath condensate method (p<0.05) but is not significantly more effective than reported 3-stage impactor method (p>0.05). In summary, electret filters are potential in collecting non-volatile biomarkers in human exhaled breath not only because it was simpler, cheaper and easier to use than traditional methods but also for its better collecting performance. PMID:26934615

  13. Collective properties of injection-induced earthquake sequences: 1. Model description and directivity bias

    NASA Astrophysics Data System (ADS)

    Dempsey, David; Suckale, Jenny

    2016-05-01

    Induced seismicity is of increasing concern for oil and gas, geothermal, and carbon sequestration operations, with several M > 5 events triggered in recent years. Modeling plays an important role in understanding the causes of this seismicity and in constraining seismic hazard. Here we study the collective properties of induced earthquake sequences and the physics underpinning them. In this first paper of a two-part series, we focus on the directivity ratio, which quantifies whether fault rupture is dominated by one (unilateral) or two (bilateral) propagating fronts. In a second paper, we focus on the spatiotemporal and magnitude-frequency distributions of induced seismicity. We develop a model that couples a fracture mechanics description of 1-D fault rupture with fractal stress heterogeneity and the evolving pore pressure distribution around an injection well that triggers earthquakes. The extent of fault rupture is calculated from the equations of motion for two tips of an expanding crack centered at the earthquake hypocenter. Under tectonic loading conditions, our model exhibits a preference for unilateral rupture and a normal distribution of hypocenter locations, two features that are consistent with seismological observations. On the other hand, catalogs of induced events when injection occurs directly onto a fault exhibit a bias toward ruptures that propagate toward the injection well. This bias is due to relatively favorable conditions for rupture that exist within the high-pressure plume. The strength of the directivity bias depends on a number of factors including the style of pressure buildup, the proximity of the fault to failure and event magnitude. For injection off a fault that triggers earthquakes, the modeled directivity bias is small and may be too weak for practical detection. For two hypothetical injection scenarios, we estimate the number of earthquake observations required to detect directivity bias.

  14. Modeling the Transitions between Collective and Solitary Migration Phenotypes in Cancer Metastasis

    PubMed Central

    Huang, Bin; Jolly, Mohit Kumar; Lu, Mingyang; Tsarfaty, Ilan; Ben-Jacob, Eshel; Onuchic, Jose’ N

    2015-01-01

    Cellular plasticity during cancer metastasis is a major clinical challenge. Two key cellular plasticity mechanisms —Epithelial-to-Mesenchymal Transition (EMT) and Mesenchymal-to-Amoeboid Transition (MAT) – have been carefully investigated individually, yet a comprehensive understanding of their interconnections remains elusive. Previously, we have modeled the dynamics of the core regulatory circuits for both EMT (miR-200/ZEB/miR-34/SNAIL) and MAT (Rac1/RhoA). We now extend our previous work to study the coupling between these two core circuits by considering the two microRNAs (miR-200 and miR-34) as external signals to the core MAT circuit. We show that this coupled circuit enables four different stable steady states (phenotypes) that correspond to hybrid epithelial/mesenchymal (E/M), mesenchymal (M), amoeboid (A) and hybrid amoeboid/mesenchymal (A/M) phenotypes. Our model recapitulates the metastasis-suppressing role of the microRNAs even in the presence of EMT-inducing signals like Hepatocyte Growth Factor (HGF). It also enables mapping the microRNA levels to the transitions among various cell migration phenotypes. Finally, it offers a mechanistic understanding for the observed phenotypic transitions among different cell migration phenotypes, specifically the Collective-to-Amoeboid Transition (CAT). PMID:26627083

  15. Collective behavior and predation success in a predator-prey model inspired by hunting bats

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Abaid, Nicole

    2013-12-01

    We establish an agent-based model to study the impact of prey behavior on the hunting success of predators. The predators and prey are modeled as self-propelled particles moving in a three-dimensional domain and subject to specific sensing abilities and behavioral rules inspired by bat hunting. The predators randomly search for prey. The prey either align velocity directions with peers, defined as "interacting" prey, or swarm "independently" of peer presence; both types of prey are subject to additive noise. In a simulation study, we find that interacting prey using low noise have the maximum predation avoidance because they form localized large groups, while they suffer high predation as noise increases due to the formation of broadly dispersed small groups. Independent prey, which are likely to be uniformly distributed in the domain, have higher predation risk under a low noise regime as they traverse larger spatial extents. These effects are enhanced in large prey populations, which exhibit more ordered collective behavior or more uniform spatial distribution as they are interacting or independent, respectively.

  16. Modeling the Transitions between Collective and Solitary Migration Phenotypes in Cancer Metastasis

    NASA Astrophysics Data System (ADS)

    Huang, Bin; Jolly, Mohit Kumar; Lu, Mingyang; Tsarfaty, Ilan; Ben-Jacob, Eshel; Onuchic, Jose' N.

    2015-12-01

    Cellular plasticity during cancer metastasis is a major clinical challenge. Two key cellular plasticity mechanisms —Epithelial-to-Mesenchymal Transition (EMT) and Mesenchymal-to-Amoeboid Transition (MAT) - have been carefully investigated individually, yet a comprehensive understanding of their interconnections remains elusive. Previously, we have modeled the dynamics of the core regulatory circuits for both EMT (miR-200/ZEB/miR-34/SNAIL) and MAT (Rac1/RhoA). We now extend our previous work to study the coupling between these two core circuits by considering the two microRNAs (miR-200 and miR-34) as external signals to the core MAT circuit. We show that this coupled circuit enables four different stable steady states (phenotypes) that correspond to hybrid epithelial/mesenchymal (E/M), mesenchymal (M), amoeboid (A) and hybrid amoeboid/mesenchymal (A/M) phenotypes. Our model recapitulates the metastasis-suppressing role of the microRNAs even in the presence of EMT-inducing signals like Hepatocyte Growth Factor (HGF). It also enables mapping the microRNA levels to the transitions among various cell migration phenotypes. Finally, it offers a mechanistic understanding for the observed phenotypic transitions among different cell migration phenotypes, specifically the Collective-to-Amoeboid Transition (CAT).

  17. Modeling the Transitions between Collective and Solitary Migration Phenotypes in Cancer Metastasis.

    PubMed

    Huang, Bin; Jolly, Mohit Kumar; Lu, Mingyang; Tsarfaty, Ilan; Ben-Jacob, Eshel; Onuchic, Jose' N

    2015-01-01

    Cellular plasticity during cancer metastasis is a major clinical challenge. Two key cellular plasticity mechanisms -Epithelial-to-Mesenchymal Transition (EMT) and Mesenchymal-to-Amoeboid Transition (MAT) - have been carefully investigated individually, yet a comprehensive understanding of their interconnections remains elusive. Previously, we have modeled the dynamics of the core regulatory circuits for both EMT (miR-200/ZEB/miR-34/SNAIL) and MAT (Rac1/RhoA). We now extend our previous work to study the coupling between these two core circuits by considering the two microRNAs (miR-200 and miR-34) as external signals to the core MAT circuit. We show that this coupled circuit enables four different stable steady states (phenotypes) that correspond to hybrid epithelial/mesenchymal (E/M), mesenchymal (M), amoeboid (A) and hybrid amoeboid/mesenchymal (A/M) phenotypes. Our model recapitulates the metastasis-suppressing role of the microRNAs even in the presence of EMT-inducing signals like Hepatocyte Growth Factor (HGF). It also enables mapping the microRNA levels to the transitions among various cell migration phenotypes. Finally, it offers a mechanistic understanding for the observed phenotypic transitions among different cell migration phenotypes, specifically the Collective-to-Amoeboid Transition (CAT). PMID:26627083

  18. Universal model for collective access patterns in the Internet traffic dynamics: A superstatistical approach

    NASA Astrophysics Data System (ADS)

    Tamazian, A.; Nguyen, V. D.; Markelov, O. A.; Bogachev, M. I.

    2016-07-01

    We suggest a universal phenomenological description for the collective access patterns in the Internet traffic dynamics both at local and wide area network levels that takes into account erratic fluctuations imposed by cooperative user behaviour. Our description is based on the superstatistical approach and leads to the q-exponential inter-session time and session size distributions that are also in perfect agreement with empirical observations. The validity of the proposed description is confirmed explicitly by the analysis of complete 10-day traffic traces from the WIDE backbone link and from the local campus area network downlink from the Internet Service Provider. Remarkably, the same functional forms have been observed in the historic access patterns from single WWW servers. The suggested approach effectively accounts for the complex interplay of both “calm” and “bursty” user access patterns within a single-model setting. It also provides average sojourn time estimates with reasonable accuracy, as indicated by the queuing system performance simulation, this way largely overcoming the failure of Poisson modelling of the Internet traffic dynamics.

  19. Assessing Historical Fish Community Composition Using Surveys, Historical Collection Data, and Species Distribution Models

    PubMed Central

    Labay, Ben; Cohen, Adam E.; Sissel, Blake; Hendrickson, Dean A.; Martin, F. Douglas; Sarkar, Sahotra

    2011-01-01

    Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of

  20. Enabling School Structure, Collective Responsibility, and a Culture of Academic Optimism: Toward a Robust Model of School Performance in Taiwan

    ERIC Educational Resources Information Center

    Wu, Jason H.; Hoy, Wayne K.; Tarter, C. John

    2013-01-01

    Purpose: The purpose of this research is twofold: to test a theory of academic optimism in Taiwan elementary schools and to expand the theory by adding new variables, collective responsibility and enabling school structure, to the model. Design/methodology/approach: Structural equation modeling was used to test, refine, and expand an…

  1. MATHEMATICAL MODEL FOR FABRIC FILTRATION WITH INTEGRAL PARTICLE CHARGING AND COLLECTION IN A COMBINED ELECTRIC AND FLOW FIELD

    EPA Science Inventory

    The paper describes a mathematical model for fabric filtration with integral particle charging and collection in a combined electric and flow field. The model computes the non-uniform dust cake formation as a function of the average gas-to-cloth ratio, bag diameter and length, el...

  2. Regulation of K transport in a mathematical model of the cortical collecting tubule.

    PubMed

    Strieter, J; Weinstein, A M; Giebisch, G; Stephenson, J L

    1992-12-01

    The effect of luminal flow rate and peritubular pH on Na and K transport is investigated in a mathematical model of the rabbit cortical collecting tubule. The model is used to simulate a 0.4-cm segment of tubule comprised of principal cell, alpha- and beta-intercalated cells, and lateral interspace. Calculations produce luminal profiles of Na, K, Cl, HCO3, and phosphate, as well as of electrical potential and pH. Parameter sets are developed that permit representation of both unstimulated and deoxycorticosterone acetate-stimulated tubules. A series of simulations is performed in which initial luminal flow rate is varied over the range of values between 0.1 and 30 nl/min. A marked flow-dependent enhancement of Na reabsorption and K secretion is seen, especially at lower flows, while Cl and HCO3 transport remain relatively constant. In experimental studies, it has been observed that metabolic alkalosis stimulates and metabolic acidosis inhibits K secretion, while leaving Na transport relatively unaffected [B. A. Stanton and G. Giebisch. Am. J. Physiol. 242 (Renal Fluid Electrolyte Physiol. 11): F544-F551, 1982; K. Tabei, S. Muto, Y. Ando, Y. Sakairi, and Y. Asano. J. Am. Soc. Nephrol. 1: 693, 1990; and K. Tabei, S. Muto, H. Furuya, and Y. Asano. J. Am. Soc. Nephrol. 2: 752, 1991]. Model calculations indicate that, when ion permeabilities are fixed and not dependent on pH, the impact of peritubular HCO3 on K secretion cannot be simulated. When junctional Cl permeability decreases with increasing interspace pH (E. M. Wright and J. M. Diamond. Biochim. Biophys. Acta 163: 57-74, 1968) in the model, there is a marked stimulation of K secretion with alkalosis and inhibition with acidosis. Furthermore, inclusion of a pH-dependent apical Na permeability [L. G. Palmer and G. Frindt. Am. J. Physiol. 253 (Renal Fluid Electrolyte Physiol. 22): F333-F339, 1987] that increases with increasing principal cell pH significantly reduces the change in Na+ reabsorption seen with the p

  3. Urban solid waste collection system using mathematical modelling and tools of geographic information systems.

    PubMed

    Arribas, Claudia Andrea; Blazquez, Carola Alejandra; Lamas, Alejandro

    2010-04-01

    A poorly designed urban solid waste collection system has an enormous impact on labour, operational and transport costs, and on society in general due to road contamination and negative effects on public health and the environment. This study proposes a methodology for designing an urban solid waste collection system. This methodology uses combinatorial optimisation and integer programing, and GIS tools to minimise collection time, and operational and transport costs while enhancing the current solid waste collection system. This methodology establishes feasible collection routes, determines an adequate vehicle fleet size and presents a comparative cost and sensitivity analysis of the results. The implementation of this methodology in a study case of a zone in Santiago yields significant cost savings in the total collection system. PMID:19942643

  4. Border Cell Migration: A Model System for Live Imaging and Genetic Analysis of Collective Cell Movement.

    PubMed

    Prasad, Mohit; Wang, Xiaobo; He, Li; Cai, Danfeng; Montell, Denise J

    2015-01-01

    Border cell migration in the Drosophila ovary has emerged as a genetically tractable model for studying collective cell movement. Over many years border cell migration was exclusively studied in fixed samples due to the inability to culture stage 9 egg chambers in vitro. Although culturing late-stage egg chambers was long feasible, stage 9 egg chambers survived only briefly outside the female body. We identified culture conditions that support stage 9 egg chamber development and sustain complete migration of border cells ex vivo. This protocol enables one to compare the dynamics of egg chamber development in wild-type and mutant egg chambers using time-lapse microscopy and taking advantage of a multiposition microscope with a motorized imaging stage. In addition, this protocol has been successfully used in combination with fluorescence resonance energy transfer biosensors, photo-activatable proteins, and pharmacological agents and can be used with wide-field or confocal microscopes in either an upright or an inverted configuration. PMID:26324431

  5. Receptor modeling of globally circulating airborne particles collected at Mauna Loa Observatory, Hawaii

    SciTech Connect

    Hermann, D.M.

    1988-01-01

    Weekly airborne particle samples were collected at Mauna Loa Observatory (MLO), Hawaii from February 1979 through May 1985. Receptor models were used to identify sources of airborne particles at MLO, determine compositions of particles from these sources, and assess the relative impacts of them. Major sources of ambient particles at MLO include Asian continental material, oceanic biological production of Se and SO{sub 4} species, marine particles, Asian anthropogenic material, local volcanic emissions, and basalt. Source composition profiles were developed for each component. The Asian continental component represents particles transported from Eastern Asia to the North Pacific, and the component consists of crustal material contaminated by anthropogenic emissions. To account for variations in the relative strengths of anthropogenic and crustal sources, a separate Asian anthropogenic component was also developed. During the dust season, Asian continental material accounts for 80% of total suspended particulate material (TSP) at MLO, oceanic productions of Se and SO{sub 4} 11%, marine particles 2.8%, basalt 1.9%, volcanic emissions 1.7%, and Asian anthropogenic material in excess of Asian continental material 3.2%. During the clean season, the oceanic biological production of Se and SO{sub 4} contributes 62% of TSP at MLO. Continental material contributes 22%, marine particles 6.4%, basalt 2.7%, volcanic emissions 2.4%, and anthropogenic materials in excess of continental material 4.3%.

  6. Data-collection program for Pamlico River Estuary model calibration and validation

    USGS Publications Warehouse

    Bales, Jerad D.

    1989-01-01

    An investigation is being conducted to collect and interpret continuous records relating to the flow characteristics of the Pamlico River Estuary, North Carolina, and to calibrate and validate a numerical model of estuarine hydrodynamics. The study reach is 50 kilometers long and ranges in width from 330 meters at the upstream boundary to 6.4 kilometers at the downstream end. Water levels are recorded at 6 locations along the estuary; daily water-level range is typically greater at the head of the estuary than at the mouth, most likely due to upstream narrowing of the channel. Water-quality data are recorded at 14 locations. These data indicate that saline waters with low dissolved oxygen concentrations move upstream along the bottom of the estuary. Point velocities were monitored for 3 weeks at 7 locations; vertical profiles of horizontal velocity were made at the boundaries of the study reach for about 32 hours. Local tributary inflows and wind speed and direction are also being determined.

  7. Tavis-Cummings model and collective multiqubit entanglement in trapped ions

    SciTech Connect

    Retzker, A.; Solano, E.; Reznik, B.

    2007-02-15

    We present a method of generating collective multiqubit entanglement via global addressing of an ion chain performing blue and red Tavis-Cummings interactions, where several qubits are coupled to a collective motional mode. We show that a wide family of Dicke states and irradiant states can be generated by single global laser pulses, unitarily or helped with suitable postselection techniques.

  8. Modelling informally collected quantities of bulky waste and reusable items in Austria

    SciTech Connect

    Ramusch, R. Pertl, A.; Scherhaufer, S.; Schmied, E.; Obersteiner, G.

    2015-10-15

    Highlights: • Informal collectors from Hungary collect bulky waste and reusable items in Austria. • Two methodologies were applied to estimate the informally collected quantities. • Both approaches lead to an estimation of roughly 100,000 t p.a. informally collected. • The formal Austrian system collects 72 kg/cap/yr of bulky waste, WEE & scrap metal. • Informal collection amounts to approx. 12 kg/cap/yr. - Abstract: Disparities in earnings between Western and Eastern European countries are the reason for a well-established informal sector actively involved in collection and transboundary shipment activities from Austria to Hungary. The preferred objects are reusable items and wastes within the categories bulky waste, WEEE and metals, intended to be sold on flea markets. Despite leading to a loss of recyclable resources for Austrian waste management, these informal activities may contribute to the extension of the lifetime of certain goods when they are reused in Hungary; nevertheless they are discussed rather controversially. The aim of this paper is to provide objective data on the quantities informally collected and transhipped. The unique activities of informal collectors required the development and implementation of a new set of methodologies. The concept of triangulation was used to verify results obtained by field visits, interviews and a traffic counting campaign. Both approaches lead to an estimation of approx. 100,000 t per year of reusable items informally collected in Austria. This means that in addition to the approx. 72 kg/cap/yr formally collected bulky waste, bulky waste wood, household scrap (excluding packaging) and WEEE, up to a further 12 kg/cap/yr might, in the case that informal collection is abandoned, end up as waste or in the second-hand sector.

  9. Low-speed impacts between rubble piles modeled as collections of polyhedra

    NASA Astrophysics Data System (ADS)

    Korycansky, D. G.; Asphaug, Erik

    2006-04-01

    We present results of modeling rubble piles as collections of polyhedra. The use of polyhedra allows more realistic (irregular) shapes and interactions (e.g. collisions), particularly for objects of different sizes. Rotational degrees of freedom are included in the modeling, which may be important components of the motion. We solved the equations of rigid-body dynamics, including frictional/inelastic collisions, for collections of up to several hundred elements. As a demonstration of the methods and to compare with previous work by other researchers, we simulated low-speed collisions between km-scale bodies with the same general parameters as those simulated by Leinhardt et al. [Leinhardt, Z.M., Richardson, D.C., Quinn, T., 2000. Icarus 146, 133-151]. High-speed collisions appropriate to present-day asteroid encounters require additional treatment of shock effects and fragmentation and are the subject of future work; here we study regimes appropriate to planetesimal accretion and re-accretion in the aftermath of catastrophic events. Collisions between equal-mass objects at low speeds ( <10 cms) were simulated for both head-on and off-center collisions between rubble piles made of a power-law mass spectrum of sub-elements. Very low-speed head-on collisions produce single objects from the coalescence of the impactors. For slightly higher speeds, extensive disruption occurs, but re-accretion produces a single object with most of the total mass. For increasingly higher speeds, the re-accreted object has smaller mass, finally resulting in complete catastrophic disruption with all sub-elements on escape trajectories and only small amounts of mass in re-accreted bodies. Off-center collisions at moderately low speeds produce two re-accreted objects of approximately equal mass, separating at greater than escape speed. At high speed, complete disruption occurs as with the high-speed head-on collisions. Head-on collisions at low to moderate speeds result in objects of mostly

  10. Development of a multicriteria assessment model for ranking biomass feedstock collection and transportation systems.

    PubMed

    Kumar, Amit; Sokhansanj, Shahab; Flynn, Peter C

    2006-01-01

    This study details multicriteria assessment methodology that integrates economic, social, environmental, and technical factors in order to rank alternatives for biomass collection and transportation systems. Ranking of biomass collection systems is based on cost of delivered biomass, quality of biomass supplied, emissions during collection, energy input to the chain operations, and maturity of supply system technologies. The assessment methodology is used to evaluate alternatives for collecting 1.8 x 10(6) dry t/yr based on assumptions made on performance of various assemblies of biomass collection systems. A proposed collection option using loafer/ stacker was shown to be the best option followed by ensiling and baling. Ranking of biomass transport systems is based on cost of biomass transport, emissions during transport, traffic congestion, and maturity of different technologies. At a capacity of 4 x 10(6) dry t/yr, rail transport was shown to be the best option, followed by truck transport and pipeline transport, respectively. These rankings depend highly on assumed maturity of technologies and scale of utilization. These may change if technologies such as loafing or ensiling (wet storage) methods are proved to be infeasible for large-scale collection systems. PMID:16915632

  11. p{sub t}-Multiplicity correlations in a multi-pomeron-exchange model with string collective effects

    SciTech Connect

    Armesto, N.; Derkach, D. A.; Feofilov, G. A.

    2008-12-15

    The N{sub ch} - N{sub ch} correlations experimentally observed in the central rapidity region in pp and pp-bar collisions, in a wide energy range from the ISR to Tevatron, are described in the framework of a multi-Pomeron exchange model in which string collectivity has been included in an effective way. Three parameters are obtained from the fit to data: the string tension, the average number of particles per string, and a parameter which effectively introduces string collective effects. The model successfully reproduces the rise of of charged particles, the flattening with growing rapidity density of charged particles and with the collision energy, and the negative p{sub t}-N{sub ch} correlation at low energies. The string tension and the average number of particles per string are energy independent, while the parameter that includes effectively string collective effects shows a smooth increasing behavior with energy.

  12. A Collective Case Study of Secondary Students' Model-Based Inquiry on Natural Selection through Programming in an Agent-Based Modeling Environment

    ERIC Educational Resources Information Center

    Xiang, Lin

    2011-01-01

    This is a collective case study seeking to develop detailed descriptions of how programming an agent-based simulation influences a group of 8th grade students' model-based inquiry (MBI) by examining students' agent-based programmable modeling (ABPM) processes and the learning outcomes. The context of the present study was a biology unit on…

  13. Data collection for cooperative water resources modeling in the Lower Rio Grande Basin, Fort Quitman to the Gulf of Mexico.

    SciTech Connect

    Passell, Howard David; Pallachula, Kiran; Tidwell, Vincent Carroll; Villalobos, Joshua; Piccinni, Giovanni; Brainard, James Robert; Gerik, Thomas; Morrison, Wendy; Serrat-Capdevila, Aleix; Valdes, Juan; Sheng, Zhuping; Lovato, Rene; Guitron, Alberto; Ennis, Martha Lee; Aparicio, Javier; Newman, Gretchen Carr; Michelsen, Ari M.

    2004-10-01

    Water resource scarcity around the world is driving the need for the development of simulation models that can assist in water resources management. Transboundary water resources are receiving special attention because of the potential for conflict over scarce shared water resources. The Rio Grande/Rio Bravo along the U.S./Mexican border is an example of a scarce, transboundary water resource over which conflict has already begun. The data collection and modeling effort described in this report aims at developing methods for international collaboration, data collection, data integration and modeling for simulating geographically large and diverse international watersheds, with a special focus on the Rio Grande/Rio Bravo. This report describes the basin, and the data collected. This data collection effort was spatially aggregated across five reaches consisting of Fort Quitman to Presidio, the Rio Conchos, Presidio to Amistad Dam, Amistad Dam to Falcon Dam, and Falcon Dam to the Gulf of Mexico. This report represents a nine-month effort made in FY04, during which time the model was not completed.

  14. Matching Information in National Data Collection Programs to a Model of Post-School Outcomes and Indicators. Technical Report 17.

    ERIC Educational Resources Information Center

    McGrew, Kevin S.; And Others

    This investigation mapped the correspondence between indicators at the post-school level included in the comprehensive system of educational outcomes and indicators developed by the National Center for Educational Outcomes (NCEO) and indicators included in select national data collection programs. The NCEO model articulates outcomes and indicators…

  15. EVALUATION OF SEVERAL PM 2.5 FORECAST MODELS USING DATA COLLECTED DURING THE ICARTT/NEAQS 2004 FIELD STUDY

    EPA Science Inventory

    Real-time forecasts of PM2.5 aerosol mass from seven air-quality forecast models (AQFMs) are statistically evaluated against observations collected in the northeastern U.S. and southeastern Canada from two surface networks and aircraft data during the summer of 2004 IC...

  16. Modelling informally collected quantities of bulky waste and reusable items in Austria.

    PubMed

    Ramusch, R; Pertl, A; Scherhaufer, S; Schmied, E; Obersteiner, G

    2015-10-01

    Disparities in earnings between Western and Eastern European countries are the reason for a well-established informal sector actively involved in collection and transboundary shipment activities from Austria to Hungary. The preferred objects are reusable items and wastes within the categories bulky waste, WEEE and metals, intended to be sold on flea markets. Despite leading to a loss of recyclable resources for Austrian waste management, these informal activities may contribute to the extension of the lifetime of certain goods when they are reused in Hungary; nevertheless they are discussed rather controversially. The aim of this paper is to provide objective data on the quantities informally collected and transhipped. The unique activities of informal collectors required the development and implementation of a new set of methodologies. The concept of triangulation was used to verify results obtained by field visits, interviews and a traffic counting campaign. Both approaches lead to an estimation of approx. 100,000 t per year of reusable items informally collected in Austria. This means that in addition to the approx. 72 kg/cap/yr formally collected bulky waste, bulky waste wood, household scrap (excluding packaging) and WEEE, up to a further 12 kg/cap/yr might, in the case that informal collection is abandoned, end up as waste or in the second-hand sector. PMID:26209344

  17. Collective migration models: Dynamic monitoring of leader cells in migratory/invasive disease processes

    NASA Astrophysics Data System (ADS)

    Dean, Zachary Steven

    Leader cells are a fundamental biological process that have only been investigated since the early 2000s. These cells have often been observed emerging at the edge of an artificial wound in 2D epithelial cell collective invasion, created with either a mechanical scrape from a pipette tip or from the removal of a plastic, physical blocker. During migration, the moving cells maintain cell-cell contacts, an important quality of collective migration; the leader cells originate from either the first or the second row, they increase in size compared to other cells, and they establish ruffled lamellipodia. Recent studies in 3D have also shown that cells emerging from an invading collective group that also exhibit leader-like properties. Exactly how leader cells influence and interact with follower cells as well as other cells types during collective migration, however, is another matter, and is a subject of intense investigation between many different labs and researchers. The majority of leader cell research to date has involved epithelial cells, but as collective migration is implicated in many different pathogenic diseases, such as cancer and wound healing, a better understanding of leader cells in many cell types and environments will allow significant improvement to therapies and treatments for a wide variety of disease processes. In fact, more recent studies on collective migration and invasion have broadened the field to include other cell types, including mesenchymal cancer cells and fibroblasts. However, the proper technology for picking out dynamic, single cells within a moving and changing cell population over time has severely limited previous investigation into leader cell formation and influence over other cells. In line with these previous studies, we not only bring new technology capable of dynamically monitoring leader cell formation, but we propose that leader cell behavior is more than just an epithelial process, and that it is a critical physiological

  18. Alignment vs noise in self-propelled particles: minimal models for collective motion and their continuous descriptions

    NASA Astrophysics Data System (ADS)

    Chate, Hugues

    2012-02-01

    Two important 1995 papers have marked the birth of collective motion studies in physics: Vicsek et al introduced what could now be described as the ``Ising model'' of this new subfield. This prompted Toner and Tu to propose a continuum theory of flocks which they showed to give rise to long-range orientational order even in two space dimensions. In this setting, the complexity of most natural instances of collective motion is reduced to the competition between local alignment and noise in interacting self-propelled particles. As I will show, this nevertheless gives rise to important and new physics. In this talk, I will give an update of our current knowledge about the Vicsek model, the Toner-Tu theory, and their relationship. I will also present the emerging picture of universality classes brought about by recent progress in the study of Vicsek-like models together with their continuous descriptions.

  19. Validation of a hydrodynamic-ecosystem model simulation with time-series data collected in the western English Channel

    NASA Astrophysics Data System (ADS)

    Lewis, K.; Allen, J. I.

    2009-05-01

    Evaluation is essential if ecosystem models are to be used to simulate short-term and climate scale forecasts. A three-dimensional hydrodynamic-ecosystem model (ERSEM-POLCOMS) simulation of the western English Channel for the period 2003-2005 has been validated with a series of univariate and multivariate tests using physical, biological and chemical data collected routinely at time-series station L4 (50° 15'N, 04° 13'W). Our assessment indicates a varying confidence in model ability to simulate different variables: In terms of high frequency variability there is a high level of confidence in temperature, some confidence in nutrients, especially nitrate, but much development needs to be done before there will be confidence in the model ability to simulate phytoplankton, zooplankton and bacteria at sub weekly timescales. In terms of seasonal timescales, the model captures the phytoplankton succession when diatoms and flagellates dominate the system, but performs less well when dinoflagellate blooms are dominant. The evaluation provides a benchmark for future model development, and highlights the importance of data collection for model validation and the need to expand the range of biological variables sampled. The potential for coastal observatories to play a key role in the future development of marine ecosystem models is discussed.

  20. Collective Enumeration

    PubMed Central

    Bahrami, Bahador; Didino, Daniele; Frith, Chris; Butterworth, Brian; Rees, Geraint

    2012-01-01

    Many joint decisions in everyday life (e.g., Which bar is less crowded?) depend on approximate enumeration, but very little is known about the psychological characteristics of counting together. Here we systematically investigated collective approximate enumeration. Pairs of participants made individual and collective enumeration judgments in a 2-alternative forced-choice task and when in disagreement, they negotiated joint decisions via verbal communication and received feedback about accuracy at the end of each trial. The results showed that two people could collectively count better than either one alone, but not as well as expected by previous models of collective sensory decision making in more basic perceptual domains (e.g., luminance contrast). Moreover, such collective enumeration benefited from prior, noninteractive practice showing that social learning of how to combine shared information about enumeration required substantial individual experience. Finally, the collective context had a positive but transient impact on an individual's enumeration sensitivity. This transient social influence may be explained as a motivational factor arising from the fact that members of a collective must take responsibility for their individual decisions and face the consequences of their judgments. PMID:22889187

  1. Modeling the Collective Strategic Searching of Artificial Insurgent Groups: A Particle Swarm Approach

    SciTech Connect

    Cui, Xiaohui; Potok, Thomas E

    2007-01-01

    A swarm based social adaptive model is proposed to model multiple insurgent groups?strategy searching in a dynamic changed environment. This report presents a pilot study on using the particle swarm modeling, a widely used non-linear optimal tool, to model the emergence of insurgency campaign. The objective of this research is to apply the particle swarm metaphor as a model of insurgent social adaptation for the dynamic environment and to provide insight and understanding of insurgent group strategic adaptation.

  2. Development and Implementation of a Collective Gaining Model in Teacher Negotiations.

    ERIC Educational Resources Information Center

    Brynildson, Gerald

    The traditional approach to collective bargaining as a win/loss situation in the educational field adversely affects staff members' confidence, security, and morale. Typically, those involved in this form of negotiation see only two ways to negotiate: soft and hard. Neither approach proves satisfactory because the soft negotiator often ends up…

  3. Collection Fusion Using Bayesian Estimation of a Linear Regression Model in Image Databases on the Web.

    ERIC Educational Resources Information Center

    Kim, Deok-Hwan; Chung, Chin-Wan

    2003-01-01

    Discusses the collection fusion problem of image databases, concerned with retrieving relevant images by content based retrieval from image databases distributed on the Web. Focuses on a metaserver which selects image databases supporting similarity measures and proposes a new algorithm which exploits a probabilistic technique using Bayesian…

  4. Performance Standards and Evaluations in IR Test Collections: Cluster-Based Retrieval Models.

    ERIC Educational Resources Information Center

    Shaw, W. M., Jr.; And Others

    1997-01-01

    Describes a study that computed low performance standards for the group of queries in 13 information retrieval (IR) test collections. Derived from the random graph hypothesis, these standards represent the highest levels of retrieval effectiveness that can be obtained from meaningless clustering structures. (Author/LRW)

  5. Creation of a Knowledge City in Educational Institutions: A Model for Promoting Teachers' Collective Capacity Building

    ERIC Educational Resources Information Center

    Konidari, Victoria; Abernot, Yvan

    2007-01-01

    The aim of this paper is to outline a theoretical and methodological framework for the understanding, design and creation of teachers' collective capacity through the implementation of knowledge cities in educational institutions which are registered in the context of a fourth generation of Knowledge Management. The authors suggest four pillars on…

  6. Combinatoric Models of Information Retrieval Ranking Methods and Performance Measures for Weakly-Ordered Document Collections

    ERIC Educational Resources Information Center

    Church, Lewis

    2010-01-01

    This dissertation answers three research questions: (1) What are the characteristics of a combinatoric measure, based on the Average Search Length (ASL), that performs the same as a probabilistic version of the ASL?; (2) Does the combinatoric ASL measure produce the same performance result as the one that is obtained by ranking a collection of…

  7. Modeling demographics and genetics in ex situ collections during seed storage and regeneration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of germplasm collections is to obtain representative samples of genetic variation and maintain them as living specimens that can be used in a variety of research applications. A key challenge in this objective is maintaining both genetic diversity and viability. The process of ex situ cons...

  8. Building a bridge with the customer to facilitate collecting and validating information in modeling sessions

    SciTech Connect

    Eaton, S.M.

    1994-07-21

    To build a bridge with customers, we balance the linear modeling process with the dynamics of the individuals we serve, who may feel unfamiliar, even confused, with that process. While it is recognized that human factors engineers improve the physical aspect of the workplace, they also work to integrate customers` cognitive styles, feelings, and concerns into the workplace tools. We take customers` feelings into consideration and integrate their expressed needs and concerns into the modeling sessions. After establishing an agreeable, professional relationship, we use a simple, portable CASE tool to reveal the effectiveness of NIAM. This tool, Modeler`s Assistant, is friendly enough to use directly with people who know nothing of NIAM, yet it captures all the information necessary to create complete models. The Modeler`s Assistant succeeds because it organizes the detailed information in an enhanced text format for customer validation. Customer cooperation results from our modeling sessions as they grow comfortable and become enthused about providing information.

  9. Mechanism to support generic collective communication across a variety of programming models

    DOEpatents

    Almasi, Gheorghe; Dozsa, Gabor; Kumar, Sameer

    2011-07-19

    A system and method for supporting collective communications on a plurality of processors that use different parallel programming paradigms, in one aspect, may comprise a schedule defining one or more tasks in a collective operation, an executor that executes the task, a multisend module to perform one or more data transfer functions associated with the tasks, and a connection manager that controls one or more connections and identifies an available connection. The multisend module uses the available connection in performing the one or more data transfer functions. A plurality of processors that use different parallel programming paradigms can use a common implementation of the schedule module, the executor module, the connection manager and the multisend module via a language adaptor specific to a parallel programming paradigm implemented on a processor.

  10. Non-collective Parallel I/O for Global Address Space Programming Models

    SciTech Connect

    Krishnamoorthy, Sriram; Piernas Canovas, Juan; Tipparaju, Vinod; Nieplocha, Jaroslaw; Sadayappan, Ponnuswamy

    2007-09-13

    Achieving high performance for out-of-core applications typically involves explicit management of the movement of data between the disk and the physical memory. We are developing a programming environment in which the different levels of the memory hierarchy are handled efficiently in a unified transparent framework. In this paper, we present our experiences with implementing efficient non-collective I/O (GPC-IO) as part of this framework. As a generalization of the Remote Procedure Call (RPC) that was used as a foundation for the Sun NFS system, we developed a global procedure call (GPC) to invoke procedures on a remote node to handle non-collective I/O. We consider alternative approaches that can be employed in implementing this functionality. The approaches are evaluated using a representative computation from quantum chemistry. The results demonstrate that GPC-IO achieves better absolute execution times, strong-scaling, and weakscaling than the alternatives considered.

  11. 75 FR 34767 - Proposed Information Collection Request of the Resource Justification Model (RJM); Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-18

    ...The Department of Labor, as part of its continuing effort to reduce paperwork and respondent burden, conducts a preclearance consultation program to provide the general public and Federal agencies with an opportunity to comment on proposed and/or continuing collections of information in accordance with the Paperwork Reduction Act of 1995 (PRA95) [44 U.S.C. 3506(c)(2)(A)]. This program helps to......

  12. 78 FR 14838 - Proposed Information Collection Request of the Resource Justification Model (RJM); Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-07

    ...The Department of Labor, as part of its continuing effort to reduce paperwork and respondent burden, conducts a preclearance consultation program to provide the general public and Federal agencies with an opportunity to comment on proposed and/or continuing collections of information in accordance with the Paperwork Reduction Act of 1995 (PRA95) [44 U.S.C. 3506(c)(2)(A)]. This program helps to......

  13. Modeling and enhanced sampling of molecular systems with smooth and nonlinear data-driven collective variables.

    PubMed

    Hashemian, Behrooz; Millán, Daniel; Arroyo, Marino

    2013-12-01

    Collective variables (CVs) are low-dimensional representations of the state of a complex system, which help us rationalize molecular conformations and sample free energy landscapes with molecular dynamics simulations. Given their importance, there is need for systematic methods that effectively identify CVs for complex systems. In recent years, nonlinear manifold learning has shown its ability to automatically characterize molecular collective behavior. Unfortunately, these methods fail to provide a differentiable function mapping high-dimensional configurations to their low-dimensional representation, as required in enhanced sampling methods. We introduce a methodology that, starting from an ensemble representative of molecular flexibility, builds smooth and nonlinear data-driven collective variables (SandCV) from the output of nonlinear manifold learning algorithms. We demonstrate the method with a standard benchmark molecule, alanine dipeptide, and show how it can be non-intrusively combined with off-the-shelf enhanced sampling methods, here the adaptive biasing force method. We illustrate how enhanced sampling simulations with SandCV can explore regions that were poorly sampled in the original molecular ensemble. We further explore the transferability of SandCV from a simpler system, alanine dipeptide in vacuum, to a more complex system, alanine dipeptide in explicit water. PMID:24320358

  14. Collection efficiency model based on boundary-layer characteristics for cyclones

    SciTech Connect

    Kim, W.S.; Lee, J.W.

    1997-10-01

    In cyclones, the boundary layer formed on the collecting-wall surface acts as a barrier for particle migration toward the wall due to a decreased centrifugal force on particles inside the boundary layer. A new theory for high-efficiency cyclones based on the boundary-layer characteristics is presented. The cyclone was divided into two regions: the turbulent-core region where the centrifugal force is large, and the near-wall region where the centrifugal force is small. Particle trajectories in the turbulent-core region are calculated from the mean fluid motion based on the quasi-steady drag assumption, and the collection probability of particles in the near-wall region is calculated by the deposition velocity that results from both turbulent diffusion and centrifugal force. The deposition velocity by centrifugal force was assumed equal to the equilibrium migration velocity at a certain point inside the boundary layer, and the distance to that point from the wall is assumed to be linearly proportional to the dimensionless-particle relaxation time. When the proportional constant was determined by fitting the theoretical results to experimental data, the theory showed an excellent enhancement in predicting the variation of collection efficiency with the inlet flow velocity and particle size.

  15. Mass collecting and the diet breadth model: A Great Basin example

    USGS Publications Warehouse

    Madsen, D.B.; Schmitt, D.N.

    1998-01-01

    The energetic return rates of many small animal and plant resources are often density dependent. When these resources are collected in mass, change in abundance can dramatically affect diet rank, and challenges the assumption that return rates are generally correlated with body size. When mass collecting is employed, as a result of either natural events (e.g. windrows) or technological developments (e.g. nets), population density may largely determine the overall return rate for a resource. Since a single food or resource type can be many prey types, an increase in the abundance of a food resource can change its diet rank. We examined this relationship at Lakeside Cave in northwestern Utah, and discovered that when the abundance of grasshoppers is high, and mass collecting is productive, the hunting of bighorn sheep and other large animal resources may have been abandoned, contradicting commonly held assumptions about prey size. In archaeological situations it may be necessary to determine what foraging technique was used before assuming that the presence of small animals and fish in the diet is a result of reduced foraging efficiency. ?? 1998 Academic Press Limited.

  16. Modeling and enhanced sampling of molecular systems with smooth and nonlinear data-driven collective variables

    NASA Astrophysics Data System (ADS)

    Hashemian, Behrooz; Millán, Daniel; Arroyo, Marino

    2013-12-01

    Collective variables (CVs) are low-dimensional representations of the state of a complex system, which help us rationalize molecular conformations and sample free energy landscapes with molecular dynamics simulations. Given their importance, there is need for systematic methods that effectively identify CVs for complex systems. In recent years, nonlinear manifold learning has shown its ability to automatically characterize molecular collective behavior. Unfortunately, these methods fail to provide a differentiable function mapping high-dimensional configurations to their low-dimensional representation, as required in enhanced sampling methods. We introduce a methodology that, starting from an ensemble representative of molecular flexibility, builds smooth and nonlinear data-driven collective variables (SandCV) from the output of nonlinear manifold learning algorithms. We demonstrate the method with a standard benchmark molecule, alanine dipeptide, and show how it can be non-intrusively combined with off-the-shelf enhanced sampling methods, here the adaptive biasing force method. We illustrate how enhanced sampling simulations with SandCV can explore regions that were poorly sampled in the original molecular ensemble. We further explore the transferability of SandCV from a simpler system, alanine dipeptide in vacuum, to a more complex system, alanine dipeptide in explicit water.

  17. A Model Using Local Weather Data to Determine the Effective Sampling Volume for PCB Congeners Collected on Passive Air Samplers

    PubMed Central

    2016-01-01

    We have developed and evaluated a mathematical model to determine the effective sampling volumes (Veff) of PCBs and similar compounds captured using polyurethane foam passive air samplers (PUF–PAS). We account for the variability in wind speed, air temperature, and equilibrium partitioning over the course of the deployment of the samplers. The model, provided as an annotated Matlab script, predicts the Veff as a function of physical-chemical properties of each compound and meteorology from the closest Integrated Surface Database (ISD) data set obtained through NOAA’s National Centers for Environmental Information (NCEI). The model was developed to be user-friendly, only requiring basic Matlab knowledge. To illustrate the effectiveness of the model, we evaluated three independent data sets of airborne PCBs simultaneously collected using passive and active samplers: at sites in Chicago, Lancaster, UK, and Toronto, Canada. The model provides Veff values comparable to those using depuration compounds and calibration against active samplers, yielding an average congener specific concentration method ratio (active/passive) of 1.1 ± 1.2. We applied the model to PUF–PAS samples collected in Chicago and show that previous methods can underestimate concentrations of PCBs by up to 40%, especially for long deployments, deployments conducted under warming conditions, and compounds with log Koa values less than 8. PMID:26963482

  18. A Model Using Local Weather Data to Determine the Effective Sampling Volume for PCB Congeners Collected on Passive Air Samplers.

    PubMed

    Herkert, Nicholas J; Martinez, Andres; Hornbuckle, Keri C

    2016-07-01

    We have developed and evaluated a mathematical model to determine the effective sampling volumes (Veff) of PCBs and similar compounds captured using polyurethane foam passive air samplers (PUF-PAS). We account for the variability in wind speed, air temperature, and equilibrium partitioning over the course of the deployment of the samplers. The model, provided as an annotated Matlab script, predicts the Veff as a function of physical-chemical properties of each compound and meteorology from the closest Integrated Surface Database (ISD) data set obtained through NOAA's National Centers for Environmental Information (NCEI). The model was developed to be user-friendly, only requiring basic Matlab knowledge. To illustrate the effectiveness of the model, we evaluated three independent data sets of airborne PCBs simultaneously collected using passive and active samplers: at sites in Chicago, Lancaster, UK, and Toronto, Canada. The model provides Veff values comparable to those using depuration compounds and calibration against active samplers, yielding an average congener specific concentration method ratio (active/passive) of 1.1 ± 1.2. We applied the model to PUF-PAS samples collected in Chicago and show that previous methods can underestimate concentrations of PCBs by up to 40%, especially for long deployments, deployments conducted under warming conditions, and compounds with log Koa values less than 8. PMID:26963482

  19. Strength and weaknesses of modeling the dynamics of mode-locked lasers by means of collective coordinates

    NASA Astrophysics Data System (ADS)

    Alsaleh, M.; Mback, C. B. L.; Tchomgo Felenou, E.; Tchofo Dinda, P.; Grelu, Ph; Porsezian, K.

    2016-07-01

    We address the efficiency of theoretical tools used in the development and optimization of mode-locked fiber lasers. Our discussion is based on the practical case of modeling the dynamics of a dispersion-managed fiber laser. One conventional approach uses discrete propagation equations, followed by the analysis of the numerical results through a collective coordinate projection. We compare the latter with our dynamical collective coordinate approach (DCCA), which combines both modeling and analysis in a compact form. We show that for single pulse dynamics, the DCCA allows a much quicker solution mapping in the space of cavity parameters than the conventional approach, along with a good accuracy. We also discuss the weaknesses of the DCCA, in particular when multiple pulsing bifurcations occur.

  20. Verification and adjustment of regional regression models for urban storm-runoff quality using data collected in Little Rock, Arkansas

    USGS Publications Warehouse

    Barks, C.S.

    1995-01-01

    Storm-runoff water-quality data were used to verify and, when appropriate, adjust regional regression models previously developed to estimate urban storm- runoff loads and mean concentrations in Little Rock, Arkansas. Data collected at 5 representative sites during 22 storms from June 1992 through January 1994 compose the Little Rock data base. Comparison of observed values (0) of storm-runoff loads and mean concentrations to the predicted values (Pu) from the regional regression models for nine constituents (chemical oxygen demand, suspended solids, total nitrogen, total ammonia plus organic nitrogen as nitrogen, total phosphorus, dissolved phosphorus, total recoverable copper, total recoverable lead, and total recoverable zinc) shows large prediction errors ranging from 63 to several thousand percent. Prediction errors for six of the regional regression models are less than 100 percent, and can be considered reasonable for water-quality models. Differences between 0 and Pu are due to variability in the Little Rock data base and error in the regional models. Where applicable, a model adjustment procedure (termed MAP-R-P) based upon regression with 0 against Pu was applied to improve predictive accuracy. For 11 of the 18 regional water-quality models, 0 and Pu are significantly correlated, that is much of the variation in 0 is explained by the regional models. Five of these 11 regional models consistently overestimate O; therefore, MAP-R-P can be used to provide a better estimate. For the remaining seven regional models, 0 and Pu are not significanfly correlated, thus neither the unadjusted regional models nor the MAP-R-P is appropriate. A simple estimator, such as the mean of the observed values may be used if the regression models are not appropriate. Standard error of estimate of the adjusted models ranges from 48 to 130 percent. Calibration results may be biased due to the limited data set sizes in the Little Rock data base. The relatively large values of

  1. 75 FR 16840 - Proposed Extension of Information Collection Request Submitted for Public Comment; Model Employer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-02

    ... CFR 1320.13. On February 4, 2010, the Department published a Federal Register notice (75 FR 5808... Comment; Model Employer CHIP Notice AGENCY: Employee Benefits Security Administration, Department of Labor... ] Administration is soliciting comments on the Model CHIP Employer Notice. A copy of the information...

  2. Collective migration of an epithelial monolayer in response to a model wound

    PubMed Central

    Poujade, M.; Grasland-Mongrain, E.; Hertzog, A.; Jouanneau, J.; Chavrier, P.; Ladoux, B.; Buguin, A.; Silberzan, P.

    2007-01-01

    Using an original microfabrication-based technique, we experimentally study situations in which a virgin surface is presented to a confluent epithelium with no damage made to the cells. Although inspired by wound-healing experiments, the situation is markedly different from classical scratch wounding because it focuses on the influence of the free surface and uncouples it from the other possible contributions such as cell damage and/or permeabilization. Dealing with Madin–Darby canine kidney cells on various surfaces, we found that a sudden release of the available surface is sufficient to trigger collective motility. This migration is independent of the proliferation of the cells that mainly takes place on the fraction of the surface initially covered. We find that this motility is characterized by a duality between collective and individual behaviors. On the one hand, the velocity fields within the monolayer are very long range and involve many cells in a coordinated way. On the other hand, we have identified very active “leader cells” that precede a small cohort and destabilize the border by a fingering instability. The sides of the fingers reveal a pluricellular actin “belt” that may be at the origin of a mechanical signaling between the leader and the followers. Experiments performed with autocrine cells constitutively expressing hepatocyte growth factor (HGF) or in the presence of exogenous HGF show a higher average velocity of the border and no leader. PMID:17905871

  3. Modeling municipal solid waste collection: A generalized vehicle routing model with multiple transfer stations, gather sites and inhomogeneous vehicles in time windows.

    PubMed

    Son, Le Hoang; Louati, Amal

    2016-06-01

    Municipal Solid Waste (MSW) collection is a necessary process in any municipality resulting in the quality-of-life, economic aspects and urban structuralization. The intrinsic nature of MSW collection relates to the development of effective vehicle routing models that optimize the total traveling distances of vehicles, the environmental emission and the investment costs. In this article, we propose a generalized vehicle routing model including multiple transfer stations, gather sites and inhomogeneous vehicles in time windows for MSW collection. It takes into account traveling in one-way routes, the number of vehicles per m(2) and waiting time at traffic stops for reduction of operational time. The proposed model could be used for scenarios having similar node structures and vehicles' characteristics. A case study at Danang city, Vietnam is given to illustrate the applicability of this model. The experimental results have clearly shown that the new model reduces both total traveling distances and operational hours of vehicles in comparison with those of practical scenarios. Optimal routes of vehicles on streets and markets at Danang are given. Those results are significant to practitioners and local policy makers. PMID:27036996

  4. An approach to collective behavior in cell cultures: modeling and analysis of ECIS data

    NASA Astrophysics Data System (ADS)

    Rabson, David; Lafalce, Evan; Lovelady, Douglas; Lo, Chun-Min

    2011-03-01

    We review recent results in which statistical measures of noise in ECIS data distinguished healthy cell cultures from cancerous or poisoned ones: after subtracting the ``signal,'' the 1 /fα noise in the healthy cultures shows longer short-time and long-time correlations. We discuss application of an artificial neural network to detect the cancer signal, and we demonstrate a computational model of cell-cell communication that produces signals similar to those of the experimental data. The simulation is based on the q -state Potts model with inspiration from the Bak-Tang-Wiesenfeld sand-pile model. We view the level of organization larger than cells but smaller than organs or tissues as a kind of ``mesoscopic'' biological physics, in which few-body interactions dominate, and the experiments and computational model as ways of exploring this regime.

  5. Collective learning modeling based on the kinetic theory of active particles.

    PubMed

    Burini, D; De Lillo, S; Gibelli, L

    2016-03-01

    This paper proposes a systems approach to the theory of perception and learning in populations composed of many living entities. Starting from a phenomenological description of these processes, a mathematical structure is derived which is deemed to incorporate their complexity features. The modeling is based on a generalization of kinetic theory methods where interactions are described by theoretical tools of game theory. As an application, the proposed approach is used to model the learning processes that take place in a classroom. PMID:26542123

  6. Collective learning modeling based on the kinetic theory of active particles

    NASA Astrophysics Data System (ADS)

    Burini, D.; De Lillo, S.; Gibelli, L.

    2016-03-01

    This paper proposes a systems approach to the theory of perception and learning in populations composed of many living entities. Starting from a phenomenological description of these processes, a mathematical structure is derived which is deemed to incorporate their complexity features. The modeling is based on a generalization of kinetic theory methods where interactions are described by theoretical tools of game theory. As an application, the proposed approach is used to model the learning processes that take place in a classroom.

  7. A hemodynamics model to study the collective behavior of the ventricular-arterial system

    NASA Astrophysics Data System (ADS)

    Lin Wang, Yuh-Ying; Wang, Wei-Kung

    2013-01-01

    Applying principles from complex systems to study the efficacy of integrative therapies has become a new interest in medical research. We aimed to construct a concise model for the ventricular-arterial (VA) system and to provide a systematic method for exploring its overall behavior. The transportation of blood from the heart to the peripheral arterioles via hydraulic pressure forces was described by a multi-rank model. Parts of the VA system that have strong mutual interactions were combined into a single sub system. Sub systems of four different ranks were characterized. We then applied the multi-rank model to analyze the aortic pressure wave generated by the periodic ventricular blood ejection, the renal pressure in response to the input from the VA system, and the blood flowing from the renal artery to its arterioles. Maintaining the pressure distribution along the main arteries and in all of the organs with the lowest possible ventricular input turned out to be the first principle for the operation of an efficient VA system. By this principle, we pointed out the benefit of some arterial structures in mammals, derived specific regulation rules and deduced some fundamental concepts for healing. The justification of the biomechanics in our model that differed greatly from those in the prevailing models was given. We concluded that the oscillatory motion and the pressure pulse of the arterial system can be analyzed as steady states with resonance behaviors and suggested utilizing this model to construct integrative therapies for diseases correlated with abnormality in blood circulation.

  8. Double Stimulation in the Waiting Experiment with Collectives: Testing a Vygotskian Model of the Emergence of Volitional Action.

    PubMed

    Sannino, Annalisa

    2016-03-01

    This study explores what human conduct looks like when research embraces uncertainty and distance itself from the dominant methodological demands of control and predictability. The context is the waiting experiment originally designed in Kurt Lewin's research group, discussed by Vygotsky as an instance among a range of experiments related to his notion of double stimulation. Little attention has been paid to this experiment, despite its great heuristic potential for charting the terrain of uncertainty and agency in experimental settings. Behind the notion of double stimulation lays Vygotsky's distinctive view of human beings' ability to intentionally shape their actions. Accordingly, human beings in situations of uncertainty and cognitive incongruity can rely on artifacts which serve the function of auxiliary motives and which help them undertake volitional actions. A double stimulation model depicting how such actions emerge is tested in a waiting experiment conducted with collectives, in contrast with a previous waiting experiment conducted with individuals. The model, validated in the waiting experiment with individual participants, applies only to a limited extent to the collectives. The analysis shows the extent to which double stimulation takes place in the waiting experiment with collectives, the differences between the two experiments, and what implications can be drawn for an expanded view on experiments. PMID:26318436

  9. Kinetic model of collective scattering off fast ion generated electromagnetic fluctuations in magnetized Vlasov plasma

    SciTech Connect

    Heikkinen, J.A.; Dumbrajs, O.

    1996-02-01

    From the general three-wave coupling formalism in magnetized nonrelativistic Vlasov plasma, an expression is derived that gives the differential cross section for the scattering of incident radiation off of thermal fluctuations induced by ions in a hot magnetized plasma. The model is valid to any order in thermal parameters, and can thus generalize the previous theory models to regimes where either the electron Larmor radius or the electron cyclotron resonance are significant for the scattered wave. {copyright} {ital 1996 American Institute of Physics.}

  10. Making the Transition from Print to Electronic Serial Collections: A New Model for Academic Chemistry Libraries?

    ERIC Educational Resources Information Center

    Chrzastowski, Tina E.

    2003-01-01

    Proposes a new model for an academic chemistry library based on experiences at the University of Illinois at Urbana-Champaign in which primary access to journals is electronic and print journals are archived unbound in a remote storage facility following local access for one year. Discusses results of a feasibility study. (Author/LRW)

  11. Modeling the collective relaxation time of glass-forming polymers at intermediate length scales: Application to polyisobutylene

    NASA Astrophysics Data System (ADS)

    Colmenero, Juan; Alvarez, Fernando; Khairy, Yasmin; Arbe, Arantxa

    2013-07-01

    In a recent paper [V. N. Novikov, K. S. Schweizer, and A. P. Sokolov, J. Chem. Phys. 138, 164508 (2013)], 10.1063/1.4802771 a simple analytical ansatz has been proposed to describe the momentum transfer (Q) dependence of the collective relaxation time of glass-forming systems in a wide Q-range covering the region of the first maximum of the static structure factor S(Q) and the so-called intermediate length scale regime. In this work we have generalized this model in order to deal with glass-forming systems where the atomic diffusive processes are sub-linear in nature. This is for instance the case of glass-forming polymers. The generalized expression considers a sub-linear jump-diffusion model and reduces to the expression previously proposed for normal diffusion. The generalized ansatz has been applied to the experimental results of the Q- and temperature-dependence of polyisobutylene (PIB), which were previously published. To reduce the number of free parameters of the model to only one, we have taken advantage of atomistic molecular dynamics simulations of PIB properly validated by neutron scattering results. The model perfectly describes the experimental results capturing both, Q- and temperature-dependences. Moreover, the model also reproduces the experimental Q-dependence of the effective activation energy of the collective relaxation time in the temperature range of observation. This non-trivial result gives additional support to the way the crossover between two different relaxation mechanisms of density fluctuations is formulated in the model.

  12. Developing a model for understanding patient collection of observations of daily living: A qualitative meta-synthesis of the Project HealthDesign Program

    PubMed Central

    Cohen, Deborah J.; Keller, Sara R.; Hayes, Gillian R.; Dorr, David A.; Ash, Joan S.; Sittig, Dean F.

    2016-01-01

    We conducted a meta-synthesis of five different studies that developed, tested, and implemented new technologies for the purpose of collecting Observations of Daily Living (ODL). From this synthesis, we developed a model to explain user motivation as it relates to ODL collection. We describe this model that includes six factors that motivate patients’ collection of ODL data: usability, illness experience, relevance of ODLs, information technology infrastructure, degree of burden, and emotional activation. We show how these factors can act as barriers or facilitators to the collection of ODL data and how interacting with care professionals and sharing ODL data may also influence ODL collection, health-related awareness, and behavior change. The model we developed and used to explain ODL collection can be helpful to researchers and designers who study and develop new, personal health technologies to empower people to improve their health. PMID:26949381

  13. The impact of Local Authorities' interventions on household waste collection: a case study approach using time series modelling.

    PubMed

    Cole, Christine; Quddus, Mohammed; Wheatley, Andrew; Osmani, Mohamed; Kay, Kath

    2014-02-01

    At a local Government level there have been many interventions and changes made to household waste collection services to meet new regulatory requirements. These changes include separate collection of recyclable and organic materials. This paper has used a time series model to quantify the success of interventions introduced by a LA. The case study was a medium sized UK LA, Charnwood Borough Council (CBC), the research analyses monthly data of quantities of recyclates, garden waste for composting and residual waste for landfill disposal. The time series model was validated with a five year data set and used to measure the impacts of the various changes to identify which intervention was the most successful, while controlling for season and number of working days. The results show the interventions analysed both had abrupt and permanent positive impacts on the yield of recyclable materials, and a corresponding negative impact on the residual waste. The model could be added to the National data base to help LAs to compare interventions and to understand which schemes encourage householder participation and improve recycling performance. PMID:24256716

  14. Prospects of Genomic Prediction in the USDA Soybean Germplasm Collection: Historical Data Creates Robust Models for Enhancing Selection of Accessions

    PubMed Central

    Jarquin, Diego; Specht, James; Lorenz, Aaron

    2016-01-01

    The identification and mobilization of useful genetic variation from germplasm banks for use in breeding programs is critical for future genetic gain and protection against crop pests. Plummeting costs of next-generation sequencing and genotyping is revolutionizing the way in which researchers and breeders interface with plant germplasm collections. An example of this is the high density genotyping of the entire USDA Soybean Germplasm Collection. We assessed the usefulness of 50K single nucleotide polymorphism data collected on 18,480 domesticated soybean (Glycine max) accessions and vast historical phenotypic data for developing genomic prediction models for protein, oil, and yield. Resulting genomic prediction models explained an appreciable amount of the variation in accession performance in independent validation trials, with correlations between predicted and observed reaching up to 0.92 for oil and protein and 0.79 for yield. The optimization of training set design was explored using a series of cross-validation schemes. It was found that the target population and environment need to be well represented in the training set. Second, genomic prediction training sets appear to be robust to the presence of data from diverse geographical locations and genetic clusters. This finding, however, depends on the influence of shattering and lodging, and may be specific to soybean with its presence of maturity groups. The distribution of 7608 nonphenotyped accessions was examined through the application of genomic prediction models. The distribution of predictions of phenotyped accessions was representative of the distribution of predictions for nonphenotyped accessions, with no nonphenotyped accessions being predicted to fall far outside the range of predictions of phenotyped accessions. PMID:27247288

  15. Prospects of Genomic Prediction in the USDA Soybean Germplasm Collection: Historical Data Creates Robust Models for Enhancing Selection of Accessions.

    PubMed

    Jarquin, Diego; Specht, James; Lorenz, Aaron

    2016-01-01

    The identification and mobilization of useful genetic variation from germplasm banks for use in breeding programs is critical for future genetic gain and protection against crop pests. Plummeting costs of next-generation sequencing and genotyping is revolutionizing the way in which researchers and breeders interface with plant germplasm collections. An example of this is the high density genotyping of the entire USDA Soybean Germplasm Collection. We assessed the usefulness of 50K single nucleotide polymorphism data collected on 18,480 domesticated soybean (Glycine max) accessions and vast historical phenotypic data for developing genomic prediction models for protein, oil, and yield. Resulting genomic prediction models explained an appreciable amount of the variation in accession performance in independent validation trials, with correlations between predicted and observed reaching up to 0.92 for oil and protein and 0.79 for yield. The optimization of training set design was explored using a series of cross-validation schemes. It was found that the target population and environment need to be well represented in the training set. Second, genomic prediction training sets appear to be robust to the presence of data from diverse geographical locations and genetic clusters. This finding, however, depends on the influence of shattering and lodging, and may be specific to soybean with its presence of maturity groups. The distribution of 7608 nonphenotyped accessions was examined through the application of genomic prediction models. The distribution of predictions of phenotyped accessions was representative of the distribution of predictions for nonphenotyped accessions, with no nonphenotyped accessions being predicted to fall far outside the range of predictions of phenotyped accessions. PMID:27247288

  16. Spatio-Temporal Dynamics in Collective Frog Choruses Examined by Mathematical Modeling and Field Observations

    NASA Astrophysics Data System (ADS)

    Aihara, Ikkyu; Mizumoto, Takeshi; Otsuka, Takuma; Awano, Hiromitsu; Nagira, Kohei; Okuno, Hiroshi G.; Aihara, Kazuyuki

    2014-01-01

    This paper reports theoretical and experimental studies on spatio-temporal dynamics in the choruses of male Japanese tree frogs. First, we theoretically model their calling times and positions as a system of coupled mobile oscillators. Numerical simulation of the model as well as calculation of the order parameters show that the spatio-temporal dynamics exhibits bistability between two-cluster antisynchronization and wavy antisynchronization, by assuming that the frogs are attracted to the edge of a simple circular breeding site. Second, we change the shape of the breeding site from the circle to rectangles including a straight line, and evaluate the stability of two-cluster and wavy antisynchronization. Numerical simulation shows that two-cluster antisynchronization is more frequently observed than wavy antisynchronization. Finally, we recorded frog choruses at an actual paddy field using our sound-imaging method. Analysis of the video demonstrated a consistent result with the aforementioned simulation: namely, two-cluster antisynchronization was more frequently realized.

  17. Data collection handbook to support modeling the impacts of radioactive material in soil

    SciTech Connect

    Yu, C.; Cheng, J.J.; Jones, L.G.; Wang, Y.Y.; Faillace, E.; Loureiro, C.; Chia, Y.P.

    1993-04-01

    A pathway analysis computer code called RESRAD has been developed for implementing US Department of Energy Residual Radioactive Material Guidelines. Hydrogeological, meteorological, geochemical, geometrical (size, area, depth), and material-related (soil, concrete) parameters are used in the RESRAD code. This handbook discusses parameter definitions, typical ranges, variations, measurement methodologies, and input screen locations. Although this handbook was developed primarily to support the application of RESRAD, the discussions and values are valid for other model applications.

  18. Large-scale collection and annotation of gene models for date palm (Phoenix dactylifera, L.).

    PubMed

    Zhang, Guangyu; Pan, Linlin; Yin, Yuxin; Liu, Wanfei; Huang, Dawei; Zhang, Tongwu; Wang, Lei; Xin, Chengqi; Lin, Qiang; Sun, Gaoyuan; Ba Abdullah, Mohammed M; Zhang, Xiaowei; Hu, Songnian; Al-Mssallem, Ibrahim S; Yu, Jun

    2012-08-01

    The date palm (Phoenix dactylifera L.), famed for its sugar-rich fruits (dates) and cultivated by humans since 4,000 B.C., is an economically important crop in the Middle East, Northern Africa, and increasingly other places where climates are suitable. Despite a long history of human cultivation, the understanding of P. dactylifera genetics and molecular biology are rather limited, hindered by lack of basic data in high quality from genomics and transcriptomics. Here we report a large-scale effort in generating gene models (assembled expressed sequence tags or ESTs and mapped to a genome assembly) for P. dactylifera, using the long-read pyrosequencing platform (Roche/454 GS FLX Titanium) in high coverage. We built fourteen cDNA libraries from different P. dactylifera tissues (cultivar Khalas) and acquired 15,778,993 raw sequencing reads-about one million sequencing reads per library-and the pooled sequences were assembled into 67,651 non-redundant contigs and 301,978 singletons. We annotated 52,725 contigs based on the plant databases and 45 contigs based on functional domains referencing to the Pfam database. From the annotated contigs, we assigned GO (Gene Ontology) terms to 36,086 contigs and KEGG pathways to 7,032 contigs. Our comparative analysis showed that 70.6 % (47,930), 69.4 % (47,089), 68.4 % (46,441), and 69.3 % (47,048) of the P. dactylifera gene models are shared with rice, sorghum, Arabidopsis, and grapevine, respectively. We also assigned our gene models into house-keeping and tissue-specific genes based on their tissue specificity. PMID:22736259

  19. Transaction-neutral implanted data collection interface as EMR driver: a model for emerging distributed medical technologies.

    PubMed

    Lorence, Daniel; Sivaramakrishnan, Anusha; Richards, Michael

    2010-08-01

    Electronic Medical Record (EMR) and Electronic Health Record (EHR) adoption continues to lag across the US. Cost, inconsistent formats, and concerns about control of patient information are among the most common reasons for non-adoption in physician practice settings. The emergence of wearable and implanted mobile technologies, employed in distributed environments, promises a fundamentally different information infrastructure, which could serve to minimize existing adoption resistance. Proposed here is one technology model for overcoming adoption inconsistency and high organization-specific implementation costs, using seamless, patient controlled data collection. While the conceptual applications employed in this technology set are provided by way of illustration, they may also serve as a transformative model for emerging EMR/EHR requirements. PMID:20703915

  20. Nanostructuring for enhanced absorption and carrier collection in CZTS-based solar cells: Coupled optical and electrical modeling

    NASA Astrophysics Data System (ADS)

    Abdelraouf, Omar A. M.; Allam, Nageh K.

    2016-04-01

    Earth-abundant Cu2ZnSnS4 (CZTS) is being considered as a potential photon-absorbing layer for low cost thin film solar cells. Nanostructured light trapping is recently investigated as a technique for enhancing the efficiency of CZTS solar cells. Herein, we used coupled electrical and optical modeling for different combinations of nanostructured CZTS solar cells to guide optimization of such nanostructures. The model is validated by a comparison of simulated I-V curves with previously reported experimental data. A very good agreement is achieved. Simulations are used to demonstrate that nanostructures can be tailored to maximize the absorption, carrier generation, carrier collection, and efficiency in CZTS solar cells. All proposed nanostructured solar cells showed enhancement in the overall conversion efficiency.

  1. Collective Cell Motion in an Epithelial Sheet Can Be Quantitatively Described by a Stochastic Interacting Particle Model

    PubMed Central

    Cochet, Olivier; Grasland-Mongrain, Erwan; Silberzan, Pascal; Hakim, Vincent

    2013-01-01

    Modelling the displacement of thousands of cells that move in a collective way is required for the simulation and the theoretical analysis of various biological processes. Here, we tackle this question in the controlled setting where the motion of Madin-Darby Canine Kidney (MDCK) cells in a confluent epithelium is triggered by the unmasking of free surface. We develop a simple model in which cells are described as point particles with a dynamic based on the two premises that, first, cells move in a stochastic manner and, second, tend to adapt their motion to that of their neighbors. Detailed comparison to experimental data show that the model provides a quantitatively accurate description of cell motion in the epithelium bulk at early times. In addition, inclusion of model “leader” cells with modified characteristics, accounts for the digitated shape of the interface which develops over the subsequent hours, providing that leader cells invade free surface more easily than other cells and coordinate their motion with their followers. The previously-described progression of the epithelium border is reproduced by the model and quantitatively explained. PMID:23505356

  2. Evolution of collective motion in a model glass-forming liquid during physical aging

    NASA Astrophysics Data System (ADS)

    Shavit, Amit; Douglas, Jack F.; Riggleman, Robert A.

    2013-03-01

    At temperatures moderately below their glass transition temperature, the properties of many glass-forming materials can evolve slowly with time in a process known as physical aging whereby the thermodynamic, mechanical, and dynamic properties all drift towards their equilibrium values. In this work, we study the evolution of the thermodynamic and dynamic properties during physical aging for a model polymer glass. Specifically, we test the relationship between an estimate of the size of the cooperative rearrangements taking the form of strings and the effective structural relaxation time predicted by the Adam-Gibbs relationship for both an equilibrium supercooled liquid and the same fluid undergoing physical aging towards equilibrium after a series of temperature jumps. We find that there is apparently a close correlation between a structural feature of the fluid, the size of the string-like rearrangements, and the structural relaxation time, although the relationship for the aging fluid appears to be distinct from that of the fluid at equilibrium.

  3. Does Model Development Ahead of Data Collection Have Merit? A Case for Advancing Non-Local Fluvial Transport Theories

    NASA Astrophysics Data System (ADS)

    Voller, V. R.; Falcini, F.; Foufoula-Georgiou, E.; Ganti, V.; Paola, C.; Hill, K. M.; Swenson, J. B.; Longjas, A.

    2013-12-01

    The purpose of this work is to suggest how experiments might be constructed to provide data to test recently proposed phenomenological non-local model of depositional transport; formulated on the basis of morphological arguments but with limited data. A sound methodology for developing models of geological systems is to first collect significant data and then carefully identify an appropriate model form and parameters. An alternative approach is to construct what might be referred to as a phenomenological model, where limited observation of the system is used to suggest an appropriate mathematical form that matches the critical nature of the physical system behavior. By their nature, phenomenological models are often developed within a fairly narrow range of observations. In this way, interesting findings can occur when the models are modified and exercised across wider physical domains, in particular in domains where there is an absence of hard data to corroborate or invalidate the model predictions. Although this approach might be frown on my some, it is important to recognize the stellar and proven track record of phenomenological models, which despite the original scarcity of data, often pave the way to new perspectives and important findings. The poster child example is the Higgs boson. In the early 60's manipulation of the quantum field equations revealed a critical inconsistency related to the masses of fundamental particles that could only be mathematically resolved by assuming that they operated within a field that would exert drag; this conjecture took almost fifty years and the vast experimental operation of the Large Hadron Collider to physically confirm. In this work we examine a current phenomenological model used to describe non-local transport in fluvial sediment domains. This model has its genesis in attempting to describe the shapes of hill slope profiles, while acknowledging the fact that two points of the landscape with the same local slope are

  4. Using field data to test locust migratory band collective movement models

    PubMed Central

    Buhl, J.; Sword, Gregory A.; Simpson, Stephen J.

    2012-01-01

    Wingless locust nymphs can form massive migratory groups known as bands, whose coordinated movement results from local interactions. We analysed the spatial distribution of locusts within naturally occurring bands and compared them with computer simulations to infer which interaction rules are used by individuals. We found that the empirical radial distribution of neighbours around a focal individual was isotropic, indicating a tendency for locusts to interact with neighbours all around them, rather than a bias towards pursuing individuals ahead or escaping from the ones following behind. By using maps of neighbour densities and pair correlation functions, we found evidence for a short-range repulsion force, balanced by a clustering force, presumably alignment and/or attraction, at a distance of around 3 cm. These results were similar to those observed when using a ‘zonal’ self-propelled particles model where repulsion/alignment/attraction forces are delimited by concentric circular zones of set radii. However, the profiles obtained either by using different combinations of forces, limiting the number of neighbours involved in interactions, or by varying the range of some zones, all appeared to produce similar results, thereby limiting the ability to more precisely determine the rules underlying locust interactions. PMID:24312729

  5. Collection and three-dimensional modeling of GPS and tilt data at Merapi volcano, Java

    NASA Astrophysics Data System (ADS)

    Beauducel, FrançOis; Cornet, FrançOis H.

    1999-01-01

    We study here the deformations associated with the November 1996 to March 1997 eruption period at Mount Merapi (Central Java), one of the most active volcanoes in Indonesia. This activity period includes a vertical explosion on January 17 and an increase of the lava dome volume by about 3×106 m3. Two Global Positioning System (GPS) campaigns have been carried out on a six-benchmark network at the beginning and at the end of the period. Relative displacements with respect to the reference point show an average subsidence of 6.5 cm. A multicomponent tilt station installed on the southeast flank, 3 km from the summit, recorded a tilt of 11.1 ± 0.7 μrad in the tangential direction and 0.9 ± 0.4 μrad in the radial direction. These data are interpreted using a three-dimensional (3-D) elastic model based on the mixed boundary element method and a near-neighbor Monte Carlo inversion. Interpretation of tilt data requires an accurate mesh for discretizing the 3-D topography. The final result supports a horizontal elliptic magma source located 8.5 ± 0.4 km below the summit and 2 ± 0.4 km to the east of it. In particular, the data cannot be consistent with the location of a magma chamber determined from seismic activity analysis (i.e., 2 km below the summit). The computed depth depends strongly on the source shape and cannot be constrained properly because of the small amount of data. The computed deflation of 11 ± 2×106 m3 is about 3 times larger than the observed increase in the lava dome volume. This difference is attributed to rock avalanches and pyroclastic flows on the flanks of the volcano.

  6. Collective motion

    NASA Astrophysics Data System (ADS)

    Vicsek, Tamás; Zafeiris, Anna

    2012-08-01

    We review the observations and the basic laws describing the essential aspects of collective motion - being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. Some emphasis is put on models that are simple and realistic enough to reproduce the numerous related observations and are useful for developing concepts for a better understanding of the complexity of systems consisting of many simultaneously moving entities. As such, these models allow the establishing of a few fundamental principles of flocking. In particular, it is demonstrated, that in spite of considerable differences, a number of deep analogies exist between equilibrium statistical physics systems and those made of self-propelled (in most cases living) units. In both cases only a few well defined macroscopic/collective states occur and the transitions between these states follow a similar scenario, involving discontinuity and algebraic divergences.

  7. Collective Commitment and Collective Efficacy: A Theoretical Model for Understanding the Motivational Dynamics of Dilemma Resolution in Inter-Professional Work

    ERIC Educational Resources Information Center

    Rose, Jo; Norwich, Brahm

    2014-01-01

    This paper presents a new theoretical model which conceptualizes inter-professional and multi-agency collaborative working, at the level of the individual within a group. This arises from a review of the literature around joint working, and is based on social psychological theories which refer to shared goals. The model assumes that collective…

  8. A Model-Based Product Evaluation Protocol for Comparison of Safety-Engineered Protection Mechanisms of Winged Blood Collection Needles.

    PubMed

    Haupt, C; Spaeth, J; Ahne, T; Goebel, U; Steinmann, D

    2016-05-01

    OBJECTIVE To evaluate differences in product characteristics and user preferences of safety-engineered protection mechanisms of winged blood collection needles. DESIGN Randomized model-based simulation study. SETTING University medical center. PARTICIPANTS A total of 33 third-year medical students. METHODS Venipuncture was performed using winged blood collection needles with 4 different safety mechanisms: (a) Venofix Safety, (b) BD Vacutainer Push Button, (c) Safety-Multifly, and (d) Surshield Surflo. Each needle type was used in 3 consecutive tries: there was an uninstructed first handling, then instructions were given according to the operating manual; subsequently, a first trial and second trial were conducted. Study end points included successful activation, activation time, single-handed activation, correct activation, possible risk of needlestick injury, possibility of deactivation, and preferred safety mechanism. RESULTS The overall successful activation rate during the second trial was equal for all 4 devices (94%-100%). Median activation time was (a) 7 s, (b) 2 s, (c) 9 s, and (d) 7 s. Single-handed activation during the second trial was (a) 18%, (b) 82%, (c) 15%, and (d) 45%. Correct activation during the second trial was (a) 3%, (b) 64%, (c) 15%, and (d) 39%. Possible risk of needlestick injury during the second trial was highest with (d). Possibility of deactivation was (a) 0%, (b) 12%, (c) 9%, and (d) 18%. Individual preferences for each system were (a) 11, (b) 17, (c) 5, and (d) 0. The main reason for preference was the comprehensive safety mechanism. CONCLUSION Significant differences exist between safety mechanisms of winged blood collection needles. Infect Control Hosp Epidemiol 2016;37:505-511. PMID:26868306

  9. Collective modes and Kosterlitz-Thouless transition in a magnetic field in the planar Nambu–Jona-Lasinio model

    DOE PAGESBeta

    Cao, Gaoqing; He, Lianyi; Zhuang, Pengfei

    2014-09-15

    It is known that a constant magnetic field is a strong catalyst of dynamical chiral symmetry breaking in 2+1 dimensions, leading to generating dynamical fermion mass even at weakest attraction. In this work we investigate the collective modes associated with the dynamical chiral symmetry breaking in a constant magnetic field in the (2+1)-dimensional Nambu–Jona-Lasinio model with continuous U(1) chiral symmetry. We introduce a self-consistent scheme to evaluate the propagators of the collective modes at the leading order in 1/N. The contributions from the vacuum and from the magnetic field are separated such that we can employ the well-established regularization schememore » for the case of vanishing magnetic field. The same scheme can be applied to the study of the next-to-leading order correction in 1/N. We show that the sigma mode is always a lightly bound state with its mass being twice the dynamical fermion mass for arbitrary strength of the magnetic field. Since the dynamics of the collective modes is always 2+1 dimensional, the finite temperature transition should be of the Kosterlitz-Thouless (KT) type. We determine the KT transition temperature TKT as well as the mass melting temperature T* as a function of the magnetic field. It is found that the pseudogap domain TKT < T < T* is enlarged with increasing strength of the magnetic field. The influence of a chiral imbalance or axial chemical potential μ5 is also studied. We find that even a constant axial chemical potential μ5 can lead to inverse magnetic catalysis of the KT transition temperature in 2+1 dimensions. As a result, the inverse magnetic catalysis behavior is actually the de Haas–van Alphen oscillation induced by the interplay between the magnetic field and the Fermi surface.« less

  10. Collective modes and Kosterlitz-Thouless transition in a magnetic field in the planar Nambu–Jona-Lasinio model

    SciTech Connect

    Cao, Gaoqing; He, Lianyi; Zhuang, Pengfei

    2014-09-15

    It is known that a constant magnetic field is a strong catalyst of dynamical chiral symmetry breaking in 2+1 dimensions, leading to generating dynamical fermion mass even at weakest attraction. In this work we investigate the collective modes associated with the dynamical chiral symmetry breaking in a constant magnetic field in the (2+1)-dimensional Nambu–Jona-Lasinio model with continuous U(1) chiral symmetry. We introduce a self-consistent scheme to evaluate the propagators of the collective modes at the leading order in 1/N. The contributions from the vacuum and from the magnetic field are separated such that we can employ the well-established regularization scheme for the case of vanishing magnetic field. The same scheme can be applied to the study of the next-to-leading order correction in 1/N. We show that the sigma mode is always a lightly bound state with its mass being twice the dynamical fermion mass for arbitrary strength of the magnetic field. Since the dynamics of the collective modes is always 2+1 dimensional, the finite temperature transition should be of the Kosterlitz-Thouless (KT) type. We determine the KT transition temperature TKT as well as the mass melting temperature T* as a function of the magnetic field. It is found that the pseudogap domain TKT < T < T* is enlarged with increasing strength of the magnetic field. The influence of a chiral imbalance or axial chemical potential μ5 is also studied. We find that even a constant axial chemical potential μ5 can lead to inverse magnetic catalysis of the KT transition temperature in 2+1 dimensions. As a result, the inverse magnetic catalysis behavior is actually the de Haas–van Alphen oscillation induced by the interplay between the magnetic field and the Fermi surface.