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Sample records for cascade reading model

  1. Nonword reading: comparing dual-route cascaded and connectionist dual-process models with human data.

    PubMed

    Pritchard, Stephen C; Coltheart, Max; Palethorpe, Sallyanne; Castles, Anne

    2012-10-01

    Two prominent dual-route computational models of reading aloud are the dual-route cascaded (DRC) model, and the connectionist dual-process plus (CDP+) model. While sharing similarly designed lexical routes, the two models differ greatly in their respective nonlexical route architecture, such that they often differ on nonword pronunciation. Neither model has been appropriately tested for nonword reading pronunciation accuracy to date. We argue that empirical data on the nonword reading pronunciation of people is the ideal benchmark for testing. Data were gathered from 45 Australian-English-speaking psychology undergraduates reading aloud 412 nonwords. To provide contrast between the models, the nonwords were chosen specifically because DRC and CDP+ disagree on their pronunciation. Both models failed to accurately match the experiment data, and both have deficiencies in nonword reading performance. However, the CDP+ model performed significantly worse than the DRC model. CDP++, the recent successor to CDP+, had improved performance over CDP+, but was also significantly worse than DRC. In addition to highlighting performance shortcomings in each model, the variety of nonword responses given by participants points to a need for models that can account for this variety.

  2. Methods of Testing and Diagnosing Model Error: Dual and Single Route Cascaded Models of Reading Aloud

    ERIC Educational Resources Information Center

    Adelman, James S.; Brown, Gordon D. A.

    2008-01-01

    Models of visual word recognition have been assessed by both factorial and regression approaches. Factorial approaches tend to provide a relatively weak test of models, and regression approaches give little indication of the sources of models' mispredictions, especially when parameters are not optimal. A new alternative method, involving…

  3. A Dual-Route Cascaded Model of Reading by Deaf Adults: Evidence for Grapheme to Viseme Conversion

    ERIC Educational Resources Information Center

    Elliott, Eeva A.; Braun, Mario; Kuhlmann, Michael; Jacobs, Arthur M.

    2012-01-01

    There is an ongoing debate whether deaf individuals access phonology when reading, and if so, what impact the ability to access phonology might have on reading achievement. However, the debate so far has been theoretically unspecific on two accounts: (a) the phonological units deaf individuals may have of oral language have not been specified and…

  4. Modeling and analysis of cascade solar cells

    NASA Technical Reports Server (NTRS)

    Ho, F. D.

    1986-01-01

    A brief review is given of the present status of the development of cascade solar cells. It is known that photovoltaic efficiencies can be improved through this development. The designs and calculations of the multijunction cells, however, are quite complicated. The main goal is to find a method which is a compromise between accuracy and simplicity for modeling a cascade solar cell. Three approaches are presently under way, among them (1) equivalent circuit approach, (2) numerical approach, and (3) analytical approach. Here, the first and the second approaches are discussed. The equivalent circuit approach using SPICE (Simulation Program, Integrated Circuit Emphasis) to the cascade cells and the cascade-cell array is highlighted. The methods of extracting parameters for modeling are discussed.

  5. Self-organized model of cascade spreading

    NASA Astrophysics Data System (ADS)

    Gualdi, S.; Medo, M.; Zhang, Y.-C.

    2011-01-01

    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a minimal self-organized model of cascade spreading based on a probabilistic response of the system elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation. For a wide range of parameters, the system is in a critical state and displays a power-law cascade-size distribution similar to the empirically observed one. We further generalize the model to reproduce volatility clustering and other observed properties of real stocks.

  6. Model Reading Institute.

    ERIC Educational Resources Information Center

    Dworkin, Nancy; Dworkin, Yehoash

    The 1978 Summer Reading Institute, which served 58 Washington, D.C., elementary school children, is described in this paper. Major characteristics of the program model are first identified, along with elements that were added to the model in the preplanning stage. Numerous aspects of the program are then described, including the make-up of the…

  7. Modeling and simulation of cascading contingencies

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  8. The Attention Cascade Model and Attentional Blink

    ERIC Educational Resources Information Center

    Shih, Shui-I

    2008-01-01

    An attention cascade model is proposed to account for attentional blinks in rapid serial visual presentation (RSVP) of stimuli. Data were collected using single characters in a single RSVP stream at 10 Hz [Shih, S., & Reeves, A. (2007). "Attentional capture in rapid serial visual presentation." "Spatial Vision", 20(4), 301-315], and single words,…

  9. Cascade models of synaptically stored memories.

    PubMed

    Fusi, Stefano; Drew, Patrick J; Abbott, L F

    2005-02-17

    Storing memories of ongoing, everyday experiences requires a high degree of plasticity, but retaining these memories demands protection against changes induced by further activity and experience. Models in which memories are stored through switch-like transitions in synaptic efficacy are good at storing but bad at retaining memories if these transitions are likely, and they are poor at storage but good at retention if they are unlikely. We construct and study a model in which each synapse has a cascade of states with different levels of plasticity, connected by metaplastic transitions. This cascade model combines high levels of memory storage with long retention times and significantly outperforms alternative models. As a result, we suggest that memory storage requires synapses with multiple states exhibiting dynamics over a wide range of timescales, and we suggest experimental tests of this hypothesis.

  10. A High Frequency Model of Cascade Noise

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    1998-01-01

    Closed form asymptotic expressions for computing high frequency noise generated by an annular cascade in an infinite duct containing a uniform flow are presented. There are two new elements in this work. First, the annular duct mode representation does not rely on the often-used Bessel function expansion resulting in simpler expressions for both the radial eigenvalues and eigenfunctions of the duct. In particular, the new representation provides an explicit approximate formula for the radial eigenvalues obviating the need for solutions of the transcendental annular duct eigenvalue equation. Also, the radial eigenfunctions are represented in terms of exponentials eliminating the numerical problems associated with generating the Bessel functions on a computer. The second new element is the construction of an unsteady response model for an annular cascade. The new construction satisfies the boundary conditions on both the cascade and duct walls simultaneously adding a new level of realism to the noise calculations. Preliminary results which demonstrate the effectiveness of the new elements are presented. A discussion of the utility of the asymptotic formulas for calculating cascade discrete tone as well as broadband noise is also included.

  11. Cascade model for fluvial geomorphology

    NASA Technical Reports Server (NTRS)

    Newman, W. I.; Turcotte, D. L.

    1990-01-01

    Erosional landscapes are generally scale invariant and fractal. Spectral studies provide quantitative confirmation of this statement. Linear theories of erosion will not generate scale-invariant topography. In order to explain the fractal behavior of landscapes a modified Fourier series has been introduced that is the basis for a renormalization approach. A nonlinear dynamical model has been introduced for the decay of the modified Fourier series coefficients that yield a fractal spectra. It is argued that a physical basis for this approach is that a fractal (or nearly fractal) distribution of storms (floods) continually renews erosional features on all scales.

  12. Transonic Cascade Measurements to Support Analytical Modeling

    DTIC Science & Technology

    2007-11-02

    RECEIVED JUL 0 12005 FINAL REPORT FOR: AFOSR GRANT F49260-02-1-0284 TRANSONIC CASCADE MEASUREMENTS TO SUPPORT ANALYTICAL MODELING Paul A. Durbin ...PAD); 650-723-1971 (JKE) durbin @vk.stanford.edu; eaton@vk.stanford.edu submitted to: Attn: Dr. John Schmisseur Air Force Office of Scientific Research...both spline and control points for subsequent wall shape definitions. An algebraic grid generator was used to generate the grid for the blade-wall

  13. Nonlinear modeling of thermoacoustically driven energy cascade

    NASA Astrophysics Data System (ADS)

    Gupta, Prateek; Scalo, Carlo; Lodato, Guido

    2016-11-01

    We present an investigation of nonlinear energy cascade in thermoacoustically driven high-amplitude oscillations, from the initial weakly nonlinear regime to the shock wave dominated limit cycle. We develop a first principle based quasi-1D model for nonlinear wave propagation in a canonical minimal unit thermoacoustic device inspired by the experimental setup of Biwa et al.. Retaining up to quadratic nonlinear terms in the governing equations, we develop model equations for nonlinear wave propagation in the proximity of differentially heated no-slip boundaries. Furthermore, we discard the effects of acoustic streaming in the present study and focus on nonlinear energy cascade due to high amplitude wave propagation. Our model correctly predicts the observed exponential growth of the thermoacoustically amplified second harmonic, as well as the energy transfer rate to higher harmonics causing wave steepening. Moreover, we note that nonlinear coupling of local pressure with heat transfer reduces thermoacoustic amplification gradually thus causing the system to reach limit cycle exhibiting shock waves. Throughout, we verify the results from the quasi-1D model with fully compressible Navier-Stokes simulations.

  14. Cascading Walks Model for Human Mobility Patterns

    PubMed Central

    Han, Xiao-Pu; Wang, Xiang-Wen; Yan, Xiao-Yong; Wang, Bing-Hong

    2015-01-01

    Background Uncovering the mechanism behind the scaling laws and series of anomalies in human trajectories is of fundamental significance in understanding many spatio-temporal phenomena. Recently, several models, e.g. the explorations-returns model (Song et al., 2010) and the radiation model for intercity travels (Simini et al., 2012), have been proposed to study the origin of these anomalies and the prediction of human movements. However, an agent-based model that could reproduce most of empirical observations without priori is still lacking. Methodology/Principal Findings In this paper, considering the empirical findings on the correlations of move-lengths and staying time in human trips, we propose a simple model which is mainly based on the cascading processes to capture the human mobility patterns. In this model, each long-range movement activates series of shorter movements that are organized by the law of localized explorations and preferential returns in prescribed region. Conclusions/Significance Based on the numerical simulations and analytical studies, we show more than five statistical characters that are well consistent with the empirical observations, including several types of scaling anomalies and the ultraslow diffusion properties, implying the cascading processes associated with the localized exploration and preferential returns are indeed a key in the understanding of human mobility activities. Moreover, the model shows both of the diverse individual mobility and aggregated scaling displacements, bridging the micro and macro patterns in human mobility. In summary, our model successfully explains most of empirical findings and provides deeper understandings on the emergence of human mobility patterns. PMID:25860140

  15. Estimating Failure Propagation in Models of Cascading Blackouts

    SciTech Connect

    Dobson, Ian; Carreras, Benjamin A; Lynch, Vickie E; Nkei, Bertrand; Newman, David E

    2005-09-01

    We compare and test statistical estimates of failure propagation in data from versions of a probabilistic model of loading-dependent cascading failure and a power systems blackout model of cascading transmission line overloads. The comparisons suggest mechanisms affecting failure propagation and are an initial step towards monitoring failure propagation from practical system data. Approximations to the probabilistic model describe the forms of probability distributions of cascade sizes.

  16. Modeling First Grade Reading Development

    ERIC Educational Resources Information Center

    Mesmer, Heidi Anne E.; Williams, Thomas O.

    2014-01-01

    This study tested a hypothesized model examining reading proficiency across first grade. It addressed how alphabetics at the beginning of the year were mediated by applied and automated skills at the middle of the year to explain actualized reading at the end of the year. The alphabetic skills of 102 first graders were measured in October and the…

  17. A stochastic model of cascades in two-dimensional turbulence

    NASA Astrophysics Data System (ADS)

    Ditlevsen, Peter D.

    2012-10-01

    The dual cascade of energy and enstrophy in 2D turbulence cannot easily be understood in terms of an analog to the Richardson-Kolmogorov scenario describing the energy cascade in 3D turbulence. The coherent upscale and downscale fluxes point to non-locality of interactions in spectral space, and thus the specific spatial structure of the flow could be important. Shell models, which lack spatial structure and have only local interactions in spectral space, indeed fail in reproducing the correct scaling for the inverse cascade of energy. In order to exclude the possibility that non-locality of interactions in spectral space is crucial for the dual cascade, we introduce a stochastic spectral model of the cascades which is local in spectral space and which shows the correct scaling for both the direct enstrophy and the inverse energy cascade.

  18. Self-organization, the cascade model, and natural hazards

    PubMed Central

    Turcotte, Donald L.; Malamud, Bruce D.; Guzzetti, Fausto; Reichenbach, Paola

    2002-01-01

    We consider the frequency-size statistics of two natural hazards, forest fires and landslides. Both appear to satisfy power-law (fractal) distributions to a good approximation under a wide variety of conditions. Two simple cellular-automata models have been proposed as analogs for this observed behavior, the forest fire model for forest fires and the sand pile model for landslides. The behavior of these models can be understood in terms of a self-similar inverse cascade. For the forest fire model the cascade consists of the coalescence of clusters of trees; for the sand pile model the cascade consists of the coalescence of metastable regions. PMID:11875206

  19. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    SciTech Connect

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  20. A modeling framework for system restoration from cascading failures.

    PubMed

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  1. A Modeling Framework for System Restoration from Cascading Failures

    PubMed Central

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems. PMID:25474408

  2. A thermal modelling of displacement cascades in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Garcia, P.; Sabathier, C.; Devynck, F.; Krack, M.; Maillard, S.

    2014-05-01

    The space and time dependent temperature distribution was studied in uranium dioxide during displacement cascades simulated by classical molecular dynamics (MD). The energy for each simulated radiation event ranged between 0.2 keV and 20 keV in cells at initial temperatures of 700 K or 1400 K. Spheres into which atomic velocities were rescaled (thermal spikes) have also been simulated by MD to simulate the thermal excitation induced by displacement cascades. Equipartition of energy was shown to occur in displacement cascades, half of the kinetic energy of the primary knock-on atom being converted after a few tenths of picoseconds into potential energy. The kinetic and potential parts of the system energy are however subjected to little variations during dedicated thermal spike simulations. This is probably due to the velocity rescaling process, which impacts a large number of atoms in this case and would drive the system away from a dynamical equilibrium. This result makes questionable MD simulations of thermal spikes carried out up to now (early 2014). The thermal history of cascades was compared to the heat equation solution of a punctual thermal excitation in UO2. The maximum volume brought to a temperature above the melting temperature during the simulated cascade events is well reproduced by this simple model. This volume eventually constitutes a relevant estimate of the volume affected by a displacement cascade in UO2. This definition of the cascade volume could also make sense in other materials, like iron.

  3. Damped trophic cascades driven by fishing in model marine ecosystems.

    PubMed

    Andersen, K H; Pedersen, M

    2010-03-07

    The largest perturbation on upper trophic levels of many marine ecosystems stems from fishing. The reaction of the ecosystem goes beyond the trophic levels directly targeted by the fishery. This reaction has been described either as a change in slope of the overall size spectrum or as a trophic cascade triggered by the removal of top predators. Here we use a novel size- and trait-based model to explore how marine ecosystems might react to perturbations from different types of fishing pressure. The model explicitly resolves the whole life history of fish, from larvae to adults. The results show that fishing does not change the overall slope of the size spectrum, but depletes the largest individuals and induces trophic cascades. A trophic cascade can propagate both up and down in trophic levels driven by a combination of changes in predation mortality and food limitation. The cascade is damped as it comes further away from the perturbed trophic level. Fishing on several trophic levels leads to a disappearance of the signature of the trophic cascade. Differences in fishing patterns among ecosystems might influence whether a trophic cascade is observed.

  4. A Model of the Reading Process.

    ERIC Educational Resources Information Center

    Thomas, David P.

    1983-01-01

    The article proposes a model of reading which incorporates functions of listening as well as speaking and reading aloud. Reading is compared with functioning of a microprocessor. Implications of the analogy and of the mode for diagnosing and remediating reading difficulties are considered. (CL)

  5. Understanding patterns and processes in models of trophic cascades

    PubMed Central

    Heath, Michael R; Speirs, Douglas C; Steele, John H; Lafferty, Kevin

    2014-01-01

    Climate fluctuations and human exploitation are causing global changes in nutrient enrichment of terrestrial and aquatic ecosystems and declining abundances of apex predators. The resulting trophic cascades have had profound effects on food webs, leading to significant economic and societal consequences. However, the strength of cascades–that is the extent to which a disturbance is diminished as it propagates through a food web–varies widely between ecosystems, and there is no formal theory as to why this should be so. Some food chain models reproduce cascade effects seen in nature, but to what extent is this dependent on their formulation? We show that inclusion of processes represented mathematically as density-dependent regulation of either consumer uptake or mortality rates is necessary for the generation of realistic ‘top-down’ cascades in simple food chain models. Realistically modelled ‘bottom-up’ cascades, caused by changing nutrient input, are also dependent on the inclusion of density dependence, but especially on mortality regulation as a caricature of, e.g. disease and parasite dynamics or intraguild predation. We show that our conclusions, based on simple food chains, transfer to a more complex marine food web model in which cascades are induced by varying river nutrient inputs or fish harvesting rates. PMID:24165353

  6. Up and down cascades: three-dimensional magnetic field model.

    PubMed

    Blanter, E M; Shnirman, M G; Le Mouël, J L

    2002-06-01

    In our previous works we already have proposed a two-dimensional model of geodynamo. Now we use the same approach to build a three-dimensional self-excited geodynamo model that generates a large scale magnetic field from whatever small initial field, using the up and down cascade effects of a multiscale turbulent system of cyclones. The multiscale system of turbulent cyclones evolves in six domains of an equatorial cylindrical layer of the core. The appearance of new cyclones is realized by two cascades: a turbulent direct cascade and an inverse cascade of coupling of similar cyclones. The interaction between the different domains is effected through a direct cascade parameter which is essential for the statistics of the long-life symmetry breaking. Generation of the secondary magnetic field results from the interaction of the components of the primary magnetic field with the turbulent cyclones. The amplification of the magnetic field is due to the transfer of energy from the turbulent helical motion to the generated magnetic field. The model demonstrates a phase transition through the parameter characterizing this energy transfer. In the supercritical domain we obtain long-term intervals of constant polarity (chrons) and quick reversals; relevant time constants agree with paleomagnetic observations. Possible application of the model to the study of the geometrical structure of the geomagnetic field (and briefly other planetary fields) is discussed.

  7. One-dimensional hydrodynamic model generating a turbulent cascade

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  8. Shelf Reading as a Collaborative Service Model

    ERIC Educational Resources Information Center

    Brown, Kevin N.; Kaspar, Wendi Arant

    2006-01-01

    Shelf reading the stacks is very often not seen as scholarly work in library circles and is therefore overlooked. However, there is a very real frustration of a patron who cannot find the material they need. There are very few studies that provide a working model for shelf reading. The authors suggest a collaborative shelf reading model based on…

  9. Information cascade, Kirman's ant colony model, and kinetic Ising model

    NASA Astrophysics Data System (ADS)

    Hisakado, Masato; Mori, Shintaro

    2015-01-01

    In this paper, we discuss a voting model in which voters can obtain information from a finite number of previous voters. There exist three groups of voters: (i) digital herders and independent voters, (ii) analog herders and independent voters, and (iii) tanh-type herders. In our previous paper Hisakado and Mori (2011), we used the mean field approximation for case (i). In that study, if the reference number r is above three, phase transition occurs and the solution converges to one of the equilibria. However, the conclusion is different from mean field approximation. In this paper, we show that the solution oscillates between the two states. A good (bad) equilibrium is where a majority of r select the correct (wrong) candidate. In this paper, we show that there is no phase transition when r is finite. If the annealing schedule is adequately slow from finite r to infinite r, the voting rate converges only to the good equilibrium. In case (ii), the state of reference votes is equivalent to that of Kirman's ant colony model, and it follows beta binomial distribution. In case (iii), we show that the model is equivalent to the finite-size kinetic Ising model. If the voters are rational, a simple herding experiment of information cascade is conducted. Information cascade results from the quenching of the kinetic Ising model. As case (i) is the limit of case (iii) when tanh function becomes a step function, the phase transition can be observed in infinite size limit. We can confirm that there is no phase transition when the reference number r is finite.

  10. Tropospheric energy cascades in a global circulation model

    NASA Astrophysics Data System (ADS)

    Brune, Sebastian; Becker, Erich

    2010-05-01

    The global horizontal kinetic energy (KE) spectrum and its budget are analyzed using results from a mechanistic GCM. The model has a standard spectral dynamical core with very high vertikal resolution up to the middle stratosphere (T330/L100). As a turbulence model we combine the Smagorinsky scheme with an energy conserving hyperdiffusion that is applied for the very smallest resolved scales. The simulation confirms a slope of the KE spectrum close to -3 in the synoptic regime where the KE is dominated by vortical modes. Towards the mesoscales the spectrum flattens and assumes a slope close to -5/3. Here divergent modes become increasingly important and even dominate the KE. Our complete analysis of the sinks and sources in the spectral KE budget reveals the overall energy fluxes through the spectrum. For the upper troposphere, the change of KE due to horizontal advection is negative for large synoptic scales. It is positive for the planetary scale, as expected, and for the mesoscales as well. This implies that the mesoscales, which include the dynamical sources of tropospheric gravity waves, are in fact sustained by the energy injection at the baroclinic scale (forward energy cascade). We find an enstrophy cascade in accordance with 2D turbulence, but zero downscaling of energy due to the vortical modes alone. In other words, the forward energy cascade in the synoptic and mesoscale regime is solely due to the divergent modes and their nonlinear interaction with the vortical modes. This picture, derived form a mechanistic model, not only lends further evidence for a generally forward energy cascade in the upper tropospheric away from the baroclinic scale. It also extends the picture proposed earlier by Tung and Orlando: The transition from a -3 to a -5/3 slope in the tropospheric macroturbulence spectrum reflects the fact, that the energy cascade due to the horizontally divergent (3D) modes is hidden behind the (2D) enstrophy cascade in the synoptic regime but

  11. Oregon Cascades Play Fairway Analysis: Raster Datasets and Models

    SciTech Connect

    Adam Brandt

    2015-11-15

    This submission includes maps of the spatial distribution of basaltic, and felsic rocks in the Oregon Cascades. It also includes a final Play Fairway Analysis (PFA) model, with the heat and permeability composite risk segments (CRS) supplied separately. Metadata for each raster dataset can be found within the zip files, in the TIF images

  12. Phonotactic constraints: Implications for models of oral reading in Russian.

    PubMed

    Ulicheva, Anastasia; Coltheart, Max; Saunders, Steven; Perry, Conrad

    2016-04-01

    The present article investigates how phonotactic rules constrain oral reading in the Russian language. The pronunciation of letters in Russian is regular and consistent, but it is subject to substantial phonotactic influence: the position of a phoneme and its phonological context within a word can alter its pronunciation. In Part 1 of the article, we analyze the orthography-to-phonology and phonology-to-phonology (i.e., phonotactic) relationships in Russian monosyllabic words. In Part 2 of the article, we report empirical data from an oral word reading task that show an effect of phonotactic dependencies on skilled reading in Russian: humans are slower when reading words where letter-phoneme correspondences are highly constrained by phonotactic rules compared with those where there are few or no such constraints present. A further question of interest in this article is how computational models of oral reading deal with the phonotactics of the Russian language. To answer this question, in Part 3, we report simulations from the Russian dual-route cascaded model (DRC) and the Russian connectionist dual-process model (CDP++) and assess the performance of the 2 models by testing them against human data.

  13. A novel information cascade model in online social networks

    NASA Astrophysics Data System (ADS)

    Tong, Chao; He, Wenbo; Niu, Jianwei; Xie, Zhongyu

    2016-02-01

    The spread and diffusion of information has become one of the hot issues in today's social network analysis. To analyze the spread of online social network information and the attribute of cascade, in this paper, we discuss the spread of two kinds of users' decisions for city-wide activities, namely the "want to take part in the activity" and "be interested in the activity", based on the users' attention in "DouBan" and the data of the city-wide activities. We analyze the characteristics of the activity-decision's spread in these aspects: the scale and scope of the cascade subgraph, the structure characteristic of the cascade subgraph, the topological attribute of spread tree, and the occurrence frequency of cascade subgraph. On this basis, we propose a new information spread model. Based on the classical independent diffusion model, we introduce three mechanisms, equal probability, similarity of nodes, and popularity of nodes, which can generate and affect the spread of information. Besides, by conducting the experiments in six different kinds of network data set, we compare the effects of three mechanisms above mentioned, totally six specific factors, on the spread of information, and put forward that the node's popularity plays an important role in the information spread.

  14. CASCADER: An M-chain gas-phase radionuclide transport and fate model. Volume 4 -- Users guide to CASCADR9

    SciTech Connect

    Cawlfield, D.E.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-09-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or dispersion. Additionally during the transport of parent and daughter radionuclides in soil, radionuclide decay may occur. This version of CASCADER called CASCADR9 starts with the concepts presented in volumes one and three of this series. For a proper understanding of how the model works, the reader should read volume one first. Also presented in this volume is a set of realistic scenarios for buried sources of radon gas, and the input and output file structure for CASCADER9.

  15. Cascading rainfall uncertainty into flood inundation impact models

    NASA Astrophysics Data System (ADS)

    Souvignet, Maxime; Freer, Jim E.; de Almeida, Gustavo A. M.; Coxon, Gemma; Neal, Jeffrey C.; Champion, Adrian J.; Cloke, Hannah L.; Bates, Paul D.

    2014-05-01

    Observed and numerical weather prediction (NWP) simulated precipitation products typically show differences in their spatial and temporal distribution. These differences can considerably influence the ability to predict hydrological responses. For flood inundation impact studies, as in forecast situations, an atmospheric-hydrologic-hydraulic model chain is needed to quantify the extent of flood risk. Uncertainties cascaded through the model chain are seldom explored, and more importantly, how potential input uncertainties propagate through this cascade, and how best to approach this, is still poorly understood. This requires a combination of modelling capabilities, the non-linear transformation of rainfall to river flow using rainfall-runoff models, and finally the hydraulic flood wave propagation based on the runoff predictions. Improving the characterisation of uncertainty, and what is important to include, in each component is important for quantifying impacts and understanding flood risk for different return periods. In this paper, we propose to address this issue by i) exploring the effects of errors in rainfall on inundation predictive capacity within an uncertainty framework by testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products) and ii) testing different techniques to cascade uncertainties (e.g. bootstrapping, PPU envelope) within the GLUE (generalised likelihood uncertainty estimation) framework. Our method cascades rainfall uncertainties into multiple rainfall-runoff model structures using the Framework for Understanding Structural Errors (FUSE). The resultant prediction uncertainties in upstream discharge provide uncertain boundary conditions that are cascaded into a simplified shallow water hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded radar data and numerical weather predictions (NWP) models are evaluated

  16. Attack robustness of cascading load model in interdependent networks

    NASA Astrophysics Data System (ADS)

    Wang, Jianwei; Wu, Yuedan; Li, Yun

    2015-08-01

    Considering the weight of a node and the coupled strength of two interdependent nodes in the different networks, we propose a method to assign the initial load of a node and construct a new cascading load model in the interdependent networks. Assuming that a node in one network will fail if its degree is 0 or its dependent node in the other network is removed from the network or the load on it exceeds its capacity, we study the influences of the assortative link (AL) and the disassortative link (DL) patterns between two networks on the robustness of the interdependent networks against cascading failures. For better evaluating the network robustness, from the local perspective of a node we present a new measure to qualify the network resiliency after targeted attacks. We show that the AL patterns between two networks can improve the robust level of the entire interdependent networks. Moreover, we obtain how to efficiently allocate the initial load and select some nodes to be protected so as to maximize the network robustness against cascading failures. In addition, we find that some nodes with the lower load are more likely to trigger the cascading propagation when the distribution of the load is more even, and also give the reasonable explanation. Our findings can help to design the robust interdependent networks and give the reasonable suggestion to optimize the allocation of the protection resources.

  17. Parsimonious Reading Models: Identifying Teachable Subskills

    ERIC Educational Resources Information Center

    Neuhaus, Graham F.; Roldan, Luis W.; Boulware-Gooden, Regina; Swank, Paul R.

    2006-01-01

    Parsimonious models of word recognition and reading comprehension were validated in a sample of third-grade readers. Word recognition was modeled as phonological awareness, decoding skill, and word processing rate. This model demonstrated the importance of unitization of letter clusters for efficient word reading. A curvilinear relation between…

  18. Cascading load model in interdependent networks with coupled strength

    NASA Astrophysics Data System (ADS)

    Wang, Jianwei; Li, Yun; Zheng, Qiaofang

    2015-07-01

    Considering the coupled strength between interdependent networks, we introduce a new method to define the initial load on an edge and propose a cascading load model in interdependent networks. We explore the robustness of the interdependent networks against cascading failures by two measures, i.e., the critical threshold βc quantifying the whole robustness of the interdependent networks to avoid the emergence of cascading failure, and the new proposed smallest capacity threshold βc,s quantifying the degree of the worst damage of the interdependent networks. We numerically find that the AL (high-degree nodes in network A connect high-degree ones in network B) link between two networks can greatly enhance the robust level of the interdependent networks against cascading failures. Especially we observe that the values of βc in the interdependent networks with both the DL (high-degree nodes in network A connect low-degree ones in network B) link and the RL (nodes in network A randomly connect ones in network B) link increase monotonically with the coupled strength, while the values of βc,s in the interdependent networks with three types of link patterns almost monotonically decreases with the coupled strength. In the interdependent networks with the AL, the value of βc first decreases and then increases with the coupled strength. We further explain this interesting phenomenon by a simple graph. In addition, we study the influence of the coupled strength on the efficiency of two attacks to destroy the interdependent networks. We find that, when the coupled strength between two networks is weaker, attacking the edges with the lower load is more easier to trigger the cascading propagation than attacking the nodes with the higher load, however, when the coupled strength in two networks is stronger, the case is on the contrary. Finally, we give reasonable explanations from the local perspective of the total capacity of all neighboring edges of a failed edge.

  19. A weakened cascade model for turbulence in astrophysical plasmas

    SciTech Connect

    Howes, G. G.; TenBarge, J. M.; Dorland, W.

    2011-10-15

    A refined cascade model for kinetic turbulence in weakly collisional astrophysical plasmas is presented that includes both the transition between weak and strong turbulence and the effect of nonlocal interactions on the nonlinear transfer of energy. The model describes the transition between weak and strong MHD turbulence and the complementary transition from strong kinetic Alfven wave (KAW) turbulence to weak dissipating KAW turbulence, a new regime of weak turbulence in which the effects of shearing by large scale motions and kinetic dissipation play an important role. The inclusion of the effect of nonlocal motions on the nonlinear energy cascade rate in the dissipation range, specifically the shearing by large-scale motions, is proposed to explain the nearly power-law energy spectra observed in the dissipation range of both kinetic numerical simulations and solar wind observations.

  20. Cascades in the Threshold Model for varying system sizes

    NASA Astrophysics Data System (ADS)

    Karampourniotis, Panagiotis; Sreenivasan, Sameet; Szymanski, Boleslaw; Korniss, Gyorgy

    2015-03-01

    A classical model in opinion dynamics is the Threshold Model (TM) aiming to model the spread of a new opinion based on the social drive of peer pressure. Under the TM a node adopts a new opinion only when the fraction of its first neighbors possessing that opinion exceeds a pre-assigned threshold. Cascades in the TM depend on multiple parameters, such as the number and selection strategy of the initially active nodes (initiators), and the threshold distribution of the nodes. For a uniform threshold in the network there is a critical fraction of initiators for which a transition from small to large cascades occurs, which for ER graphs is largerly independent of the system size. Here, we study the spread contribution of each newly assigned initiator under the TM for different initiator selection strategies for synthetic graphs of various sizes. We observe that for ER graphs when large cascades occur, the spread contribution of the added initiator on the transition point is independent of the system size, while the contribution of the rest of the initiators converges to zero at infinite system size. This property is used for the identification of large transitions for various threshold distributions. Supported in part by ARL NS-CTA, ARO, ONR, and DARPA.

  1. "Serial" Effects in Parallel Models of Reading

    ERIC Educational Resources Information Center

    Chang, Ya-Ning; Furber, Steve; Welbourne, Stephen

    2012-01-01

    There is now considerable evidence showing that the time to read a word out loud is influenced by an interaction between orthographic length and lexicality. Given that length effects are interpreted by advocates of dual-route models as evidence of serial processing this would seem to pose a serious challenge to models of single word reading which…

  2. Modeling cascading failures in the North American power grid

    NASA Astrophysics Data System (ADS)

    Kinney, R.; Crucitti, P.; Albert, R.; Latora, V.

    2005-07-01

    The North American power grid is one of the most complex technological networks, and its interconnectivity allows both for long-distance power transmission and for the propagation of disturbances. We model the power grid using its actual topology and plausible assumptions about the load and overload of transmission substations. Our results indicate that the loss of a single substation can result in up to 25% loss of transmission efficiency by triggering an overload cascade in the network. The actual transmission loss depends on the overload tolerance of the network and the connectivity of the failed substation. We systematically study the damage inflicted by the loss of single nodes, and find three universal behaviors, suggesting that 40% of the transmission substations lead to cascading failures when disrupted. While the loss of a single node can inflict substantial damage, subsequent removals have only incremental effects, in agreement with the topological resilience to less than 1% node loss.

  3. Modeling defect production in high energy collision cascades

    SciTech Connect

    Heinisch, H.L.; Singh, B.N.; Diaz de la Rubia, T.

    1993-12-01

    A multi-model approach roach (MMA) to simulating defect production processes at the atomic scale is described that incorporates molecular dynamics (MD), binary collision approximation (BCA) calculations and stochastic annealing simulations. The central hypothesis of the MMA is that the simple, fast computer codes capable of simulating large numbers of high energy cascades (e.g., BCA codes) can be made to yield the correct defect configurations when their parameters are calibrated using the results of the more physically realistic MD simulations. The calibration procedure is investigated using results of MD simulations of 25 keV cascades in copper. The configurations of point defects are extracted from the MD cascade simulations at the end of the collisional phase, similar to the information obtained with a binary collision model. The MD collisional phase defect configurations are used as input to the ALSOME annealing simulation code, and values of the ALSOME quenching parameters are determined that yield the best fit to the post-quenching defect configurations of the MD simulations.

  4. Nonautonomous equations of complicated Roessler's model and bifurcation cascades

    NASA Astrophysics Data System (ADS)

    Sanin, Andrey L.; Bagmanov, Andrey T.

    2003-10-01

    The first differential equation of the Rossler model was supplemented by the term that depends explicitly on time. The cosine amplitude defines external action on this dynamical system, and at some value of the amplitude dynamical chaos is possible. Properties of non-autonomous differential equations were investigated by using the standard methods of nonlinear dynamics including the fast Fourier transformation, point maps, phase trajectory projections. The bifurcation cascades were found under variations of the amplitude. The dynamical model presented can be considered as development of the Rossler simple model.

  5. Stochastic load-redistribution model for cascading failure propagation.

    PubMed

    Lehmann, Jörg; Bernasconi, Jakob

    2010-03-01

    A class of probabilistic models for cascading failure propagation in interconnected systems is proposed. The models are able to represent important physical characteristics of realistic load-redistribution mechanisms, e.g., that the load increments after a failure depend on the load of the failing element and that they may be distributed nonuniformly among the remaining elements. In the limit of large system sizes, the models are solved analytically in terms of generalized branching processes, and the failure propagation properties of a prototype example are analyzed in detail.

  6. Cascaded process model based control: packed absorption column application.

    PubMed

    Govindarajan, Anand; Jayaraman, Suresh Kumar; Sethuraman, Vijayalakshmi; Raul, Pramod R; Rhinehart, R Russell

    2014-03-01

    Nonlinear, adaptive, process-model based control is demonstrated in a cascaded single-input-single-output mode for pressure drop control in a pilot-scale packed absorption column. The process is shown to be nonlinear. Control is demonstrated in both servo and regulatory modes, for no wind-up in a constrained situation, and for bumpless transfer. Model adaptation is demonstrated and shown to provide process insight. The application procedure is revealed as a design guide to aid others in implementing process-model based control.

  7. Cascading and feedback in interactive models of production: a reflection of forward modeling?

    PubMed

    Dell, Gary S

    2013-08-01

    Interactive theories of lexical retrieval in language production assume that activation cascades from earlier to later processing levels, and feeds back in the reverse direction. This commentary invites Pickering & Garrod (P&G) to consider whether cascading and feedback can be seen as a form of forwarding modeling within a hierarchical production system.

  8. Ability paradox of cascading model based on betweenness

    NASA Astrophysics Data System (ADS)

    Wang, Jianwei; Xu, Bo; Wu, Yuedan

    2015-09-01

    Must Investing more resources to protect every node in a network improve the robustness of the whole network subject to target attacks? To answer this question, we investigate the cascading dynamics in some typical networks. In real networks, the load on a node is generally correlated with the betweenness. Considering the weight of a node, we give a new method to define the initial load on a node by the revised betweenness. Then we present a simple cascading model. We investigate the cascading dynamics by disabling a single key node with the highest load. We find that in BA scale-free networks, the bigger the capacity of every node, the stronger the robustness of the whole network. However, in WS networks and some random networks, when we increase the capacity of every node, instead, the robustness of the whole network is weaker. In US power grid and the China power grid, we also observe this counterintuitive phenomenon. We give a reasonable explanation by a simple illusion. By the analysis, we think that resurrections of some nodes in a ring network structure after removing a node may be the reason of this phenomenon.

  9. Boolean Models of Biological Processes Explain Cascade-Like Behavior

    PubMed Central

    Chen, Hao; Wang, Guanyu; Simha, Rahul; Du, Chenghang; Zeng, Chen

    2016-01-01

    Biological networks play a key role in determining biological function and therefore, an understanding of their structure and dynamics is of central interest in systems biology. In Boolean models of such networks, the status of each molecule is either “on” or “off” and along with the molecules interact with each other, their individual status changes from “on” to “off” or vice-versa and the system of molecules in the network collectively go through a sequence of changes in state. This sequence of changes is termed a biological process. In this paper, we examine the common perception that events in biomolecular networks occur sequentially, in a cascade-like manner, and ask whether this is likely to be an inherent property. In further investigations of the budding and fission yeast cell-cycle, we identify two generic dynamical rules. A Boolean system that complies with these rules will automatically have a certain robustness. By considering the biological requirements in robustness and designability, we show that those Boolean dynamical systems, compared to an arbitrary dynamical system, statistically present the characteristics of cascadeness and sequentiality, as observed in the budding and fission yeast cell- cycle. These results suggest that cascade-like behavior might be an intrinsic property of biological processes. PMID:26821940

  10. Boolean Models of Biological Processes Explain Cascade-Like Behavior.

    PubMed

    Chen, Hao; Wang, Guanyu; Simha, Rahul; Du, Chenghang; Zeng, Chen

    2016-01-29

    Biological networks play a key role in determining biological function and therefore, an understanding of their structure and dynamics is of central interest in systems biology. In Boolean models of such networks, the status of each molecule is either "on" or "off" and along with the molecules interact with each other, their individual status changes from "on" to "off" or vice-versa and the system of molecules in the network collectively go through a sequence of changes in state. This sequence of changes is termed a biological process. In this paper, we examine the common perception that events in biomolecular networks occur sequentially, in a cascade-like manner, and ask whether this is likely to be an inherent property. In further investigations of the budding and fission yeast cell-cycle, we identify two generic dynamical rules. A Boolean system that complies with these rules will automatically have a certain robustness. By considering the biological requirements in robustness and designability, we show that those Boolean dynamical systems, compared to an arbitrary dynamical system, statistically present the characteristics of cascadeness and sequentiality, as observed in the budding and fission yeast cell- cycle. These results suggest that cascade-like behavior might be an intrinsic property of biological processes.

  11. Ability paradox of cascading model based on betweenness

    PubMed Central

    Wang, Jianwei; Xu, Bo; Wu, Yuedan

    2015-01-01

    Must Investing more resources to protect every node in a network improve the robustness of the whole network subject to target attacks? To answer this question, we investigate the cascading dynamics in some typical networks. In real networks, the load on a node is generally correlated with the betweenness. Considering the weight of a node, we give a new method to define the initial load on a node by the revised betweenness. Then we present a simple cascading model. We investigate the cascading dynamics by disabling a single key node with the highest load. We find that in BA scale-free networks, the bigger the capacity of every node, the stronger the robustness of the whole network. However, in WS networks and some random networks, when we increase the capacity of every node, instead, the robustness of the whole network is weaker. In US power grid and the China power grid, we also observe this counterintuitive phenomenon. We give a reasonable explanation by a simple illusion. By the analysis, we think that resurrections of some nodes in a ring network structure after removing a node may be the reason of this phenomenon. PMID:26353903

  12. The Dynamics of Cascaded Monod System Models Through Five Levels

    NASA Technical Reports Server (NTRS)

    Blackwell, Charles C.; Kliss, Mark (Technical Monitor)

    1998-01-01

    A Monod system model is a set of ordinary differential equations where the terms resemble those which Monod described in his 1949 paper. We focus on the multiple trophic level case in which each trophic level uses only one of the trophic levels for its perpetuation, and no two trophic entities use the same trophic cascaded level. The treatment derives from a primary producer progressively through five trophic levels. Stability types are identified and are related to persistence, and the consequences of some intuitive scaling structures are developed. These considerations are useful to some theoretical questions in ecology and to applications such as bioreactor operation.

  13. Modelling of GaN quantum dot terahertz cascade laser

    NASA Astrophysics Data System (ADS)

    Asgari, A.; Khorrami, A. A.

    2013-03-01

    In this paper GaN based spherical quantum dot cascade lasers has been modelled, where the generation of the terahertz waves are obtained. The Schrödinger, Poisson, and the laser rate equations have been solved self-consistently including all dominant physical effects such as piezoelectric and spontaneous polarization in nitride-based QDs and the effects of the temperature. The exact value of the energy levels, the wavefunctions, the lifetimes of electron levels, and the lasing frequency are calculated. Also the laser parameters such as the optical gain, the output power and the threshold current density have been calculated at different temperatures and applied electric fields.

  14. Emotional intelligence: an integrative meta-analysis and cascading model.

    PubMed

    Joseph, Dana L; Newman, Daniel A

    2010-01-01

    Research and valid practice in emotional intelligence (EI) have been impeded by lack of theoretical clarity regarding (a) the relative roles of emotion perception, emotion understanding, and emotion regulation facets in explaining job performance; (b) conceptual redundancy of EI with cognitive intelligence and Big Five personality; and (c) application of the EI label to 2 distinct sets of constructs (i.e., ability-based EI and mixed-based EI). In the current article, the authors propose and then test a theoretical model that integrates these factors. They specify a progressive (cascading) pattern among ability-based EI facets, in which emotion perception must causally precede emotion understanding, which in turn precedes conscious emotion regulation and job performance. The sequential elements in this progressive model are believed to selectively reflect Conscientiousness, cognitive ability, and Neuroticism, respectively. "Mixed-based" measures of EI are expected to explain variance in job performance beyond cognitive ability and personality. The cascading model of EI is empirically confirmed via meta-analytic data, although relationships between ability-based EI and job performance are shown to be inconsistent (i.e., EI positively predicts performance for high emotional labor jobs and negatively predicts performance for low emotional labor jobs). Gender and race differences in EI are also meta-analyzed. Implications for linking the EI fad in personnel selection to established psychological theory are discussed.

  15. Analytical model for electromagnetic cascades in rotating electric field

    SciTech Connect

    Nerush, E. N.; Bashmakov, V. F.; Kostyukov, I. Yu.

    2011-08-15

    Electromagnetic cascades attract a lot of attention as an important quantum electrodynamics effect that will reveal itself in various electromagnetic field configurations at ultrahigh intensities. We study cascade dynamics in rotating electric field analytically and numerically. The kinetic equations for the electron-positron plasma and gamma-quanta are formulated. The scaling laws are derived and analyzed. For the cascades arising far above the threshold the dependence of the cascade parameters on the field frequency is derived. The spectra of high-energy cascade particles are calculated. The analytical results are verified by numerical simulations.

  16. Inverse energy cascade in nonlocal helical shell models of turbulence

    NASA Astrophysics Data System (ADS)

    De Pietro, Massimo; Biferale, Luca; Mailybaev, Alexei A.

    2015-10-01

    Following the exact decomposition in eigenstates of helicity for the Navier-Stokes equations in Fourier space [F. Waleffe, Phys. Fluids A 4, 350 (1992), 10.1063/1.858309], we introduce a modified version of helical shell models for turbulence with nonlocal triadic interactions. By using both an analytical argument and numerical simulation, we show that there exists a class of models, with a specific helical structure, that exhibits a statistically stable inverse energy cascade, in close analogy with that predicted for the Navier-Stokes equations restricted to the same helical interactions. We further support the idea that turbulent energy transfer is the result of a strong entanglement among triads possessing different transfer properties.

  17. "Serial" effects in parallel models of reading.

    PubMed

    Chang, Ya-Ning; Furber, Steve; Welbourne, Stephen

    2012-06-01

    There is now considerable evidence showing that the time to read a word out loud is influenced by an interaction between orthographic length and lexicality. Given that length effects are interpreted by advocates of dual-route models as evidence of serial processing this would seem to pose a serious challenge to models of single word reading which postulate a common parallel processing mechanism for reading both words and nonwords (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001; Rastle, Havelka, Wydell, Coltheart, & Besner, 2009). However, an alternative explanation of these data is that visual processes outside the scope of existing parallel models are responsible for generating the word-length related phenomena (Seidenberg & Plaut, 1998). Here we demonstrate that a parallel model of single word reading can account for the differential word-length effects found in the naming latencies of words and nonwords, provided that it includes a mapping from visual to orthographic representations, and that the nature of those orthographic representations are not preconstrained. The model can also simulate other supposedly "serial" effects. The overall findings were consistent with the view that visual processing contributes substantially to the word-length effects in normal reading and provided evidence to support the single-route theory which assumes words and nonwords are processed in parallel by a common mechanism.

  18. Modeling Collisional Cascades in Debris Disks: The Numerical Method

    NASA Astrophysics Data System (ADS)

    Gáspár, András; Psaltis, Dimitrios; Özel, Feryal; Rieke, George H.; Cooney, Alan

    2012-04-01

    We develop a new numerical algorithm to model collisional cascades in debris disks. Because of the large dynamical range in particle masses, we solve the integro-differential equations describing erosive and catastrophic collisions in a particle-in-a-box approach, while treating the orbital dynamics of the particles in an approximate fashion. We employ a new scheme for describing erosive (cratering) collisions that yields a continuous set of outcomes as a function of colliding masses. We demonstrate the stability and convergence characteristics of our algorithm and compare it with other treatments. We show that incorporating the effects of erosive collisions results in a decay of the particle distribution that is significantly faster than with purely catastrophic collisions.

  19. The Dynamics of Cascaded Monod System Models Through Five Levels

    NASA Technical Reports Server (NTRS)

    Blackwell, Charles; Kliss, Mark (Technical Monitor)

    1998-01-01

    In the context of this paper, a Monod system model is a set of ordinary differential equations in which the terms resemble those which Motion presented in his 1949 paper. Attention is directed to the multiple trophic level case in which each trophic level exploits only one of the trophic levels for its perpetuation, and no two trophic entities exploit the same trophic level (cascaded). The treatment expands from a primary producer progressively through five trophic levels. Types of stability are identified and are related to persistence, and the consequences of some intuitive scaling structures are developed. These considerations are relevant to some theoretical questions in ecology and to applications such as bioreactor operation.

  20. MODELING COLLISIONAL CASCADES IN DEBRIS DISKS: THE NUMERICAL METHOD

    SciTech Connect

    Gaspar, Andras; Psaltis, Dimitrios; Oezel, Feryal; Rieke, George H.; Cooney, Alan E-mail: dpsaltis@as.arizona.edu E-mail: grieke@as.arizona.edu

    2012-04-10

    We develop a new numerical algorithm to model collisional cascades in debris disks. Because of the large dynamical range in particle masses, we solve the integro-differential equations describing erosive and catastrophic collisions in a particle-in-a-box approach, while treating the orbital dynamics of the particles in an approximate fashion. We employ a new scheme for describing erosive (cratering) collisions that yields a continuous set of outcomes as a function of colliding masses. We demonstrate the stability and convergence characteristics of our algorithm and compare it with other treatments. We show that incorporating the effects of erosive collisions results in a decay of the particle distribution that is significantly faster than with purely catastrophic collisions.

  1. Reduced-order models of the coagulation cascade

    NASA Astrophysics Data System (ADS)

    Hansen, Kirk B.; Shadden, Shawn C.

    2015-11-01

    Previous models of flow-mediated thrombogenesis have generally included the transport and reaction of dozens of biochemical species involved in the coagulation cascade. Researchers have shown, however, that thrombin generation curves can be accurately reproduced by a significantly smaller system of reactions. These reduced-order models are based on the system of ordinary differential equations representative of a well-mixed system, however, not the system of advection-diffusion-reaction equations required to model the flow-mediated case. Additionally, they focus solely on reproducing the thrombin generation curve, although accurate representation of certain intermediate species may be required to model additional aspects of clot formation, e.g. interactions with activated and non-activated platelets. In this work, we develop a method to reduce the order of a coagulation model through optimization techniques. The results of this reduced-order model are then compared to those of the full system in several representative cardiovascular flows. This work was supported by NSF grant 1354541, the NSF GRFP, and NIH grant HL108272.

  2. Testing the inhibitory cascade model in Mesozoic and Cenozoic mammaliaforms

    PubMed Central

    2013-01-01

    Background Much of the current research in the growing field of evolutionary development concerns relating developmental pathways to large-scale patterns of morphological evolution, with developmental constraints on variation, and hence diversity, a field of particular interest. Tooth morphology offers an excellent model system for such ‘evo-devo’ studies, because teeth are well preserved in the fossil record, and are commonly used in phylogenetic analyses and as ecological proxies. Moreover, tooth development is relatively well studied, and has provided several testable hypotheses of developmental influences on macroevolutionary patterns. The recently-described Inhibitory Cascade (IC) Model provides just such a hypothesis for mammalian lower molar evolution. Derived from experimental data, the IC Model suggests that a balance between mesenchymal activators and molar-derived inhibitors determines the size of the immediately posterior molar, predicting firstly that molars either decrease in size along the tooth row, or increase in size, or are all of equal size, and secondly that the second lower molar should occupy one third of lower molar area. Here, we tested the IC Model in a large selection of taxa from diverse extant and fossil mammalian groups, ranging from the Middle Jurassic (~176 to 161 Ma) to the Recent. Results Results show that most taxa (~65%) fell within the predicted areas of the Inhibitory Cascade Model. However, members of several extinct groups fell into the regions where m2 was largest, or rarely, smallest, including the majority of the polyphyletic “condylarths”. Most Mesozoic mammals fell near the centre of the space with equality of size in all three molars. The distribution of taxa was significantly clustered by diet and by phylogenetic group. Conclusions Overall, the IC Model was supported as a plesiomorphic developmental system for Mammalia, suggesting that mammal tooth size has been subjected to this developmental constraint at

  3. An approach to crop modeling with the energy cascade.

    PubMed

    Volk, T; Bugbee, B; Wheeler, R M

    1995-01-01

    Use of plants in advanced life support requires models of crop growth to analyze data, to evaluate areas for improvement, and, for design and engineering, to predict the gas exchanges of crops. We used data from experiments at Utah State University and the Kennedy Space Center for wheat (Triticum aestivum L.) and examined it for time dependence of the major three components in the energy cascade: photosynthetic photon absorption, canopy quantum yield, and carbon use efficiency. From the Utah State data, we developed a model with a total of five trends: absorption increasing until canopy closure, then constant; quantum yield as constant, then decreasing during senescence; carbon use as constant. This system probably is the lower limit of simplicity to which a model can be reduced and yet provide substantial utility. We demonstrated this utility by using the model to predict photosynthesis and respiration for experiments at Kennedy Space Center. The most uncertainty arose in predicting a start time for the senescent decrease of canopy quantum yield. The model should be generally applicable to other crops grown in controlled environments, as a generic tool for the design of life support systems.

  4. Developmental Cascade Model for Adolescent Substance Use from Infancy to Late Adolescence

    ERIC Educational Resources Information Center

    Eiden, Rina D.; Lessard, Jared; Colder, Craig R.; Livingston, Jennifer; Casey, Meghan; Leonard, Kenneth E.

    2016-01-01

    A developmental cascade model for adolescent substance use beginning in infancy was examined in a sample of children with alcoholic and nonalcoholic parents. The model examined the role of parents' alcohol diagnoses, depression and antisocial behavior in a cascading process of risk via 3 major hypothesized pathways: first, via parental…

  5. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction

    PubMed Central

    Desikan, Radhika

    2016-01-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  6. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    PubMed

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.

  7. Towards a computational model of leukocyte adhesion cascade: Leukocyte rolling

    NASA Astrophysics Data System (ADS)

    Khismatullin, Damir

    2005-11-01

    Recruitment of leukocytes into sites of acute and chronic inflammation is a vital component of the innate immune response in humans and plays an important role in cardiovascular diseases, such as ischemia-reperfusion injury and atherosclerosis. Leukocytes extravasate into the inflamed tissue through a multi-step process called "leukocyte adhesion cascade", which involves initial contact of a leukocyte with activated endothelium (tethering), leukocyte rolling, firm adhesion, and transendothelial migration. Recently we developed a fully three-dimensional CFD model of receptor-mediated leukocyte adhesion to endothelium in a parallel-plate flow chamber. The model treats the leukocyte as a viscoelastic cell with the nucleus located in the intracellular space and cylindrical microvilli distributed over the cell membrane. Leukocyte-endothelial adhesion is assumed to be mediated by adhesion molecules expressed on the tips of cell microvilli and on endothelium. We show that the model can predict both shape changes and velocities of rolling leukocytes under physiological flow conditions. Results of this study also indicate that viscosity of the cytoplasm is a critical parameter of leukocyte adhesion, affecting the cell's ability to roll on endothelium. This work is supported by NIH Grant HL- 57446 and NCSA Grant BCS040006 and utilized the NCSA IBM p690.

  8. Towards a universal model of reading.

    PubMed

    Frost, Ram

    2012-10-01

    In the last decade, reading research has seen a paradigmatic shift. A new wave of computational models of orthographic processing that offer various forms of noisy position or context-sensitive coding have revolutionized the field of visual word recognition. The influx of such models stems mainly from consistent findings, coming mostly from European languages, regarding an apparent insensitivity of skilled readers to letter order. Underlying the current revolution is the theoretical assumption that the insensitivity of readers to letter order reflects the special way in which the human brain encodes the position of letters in printed words. The present article discusses the theoretical shortcomings and misconceptions of this approach to visual word recognition. A systematic review of data obtained from a variety of languages demonstrates that letter-order insensitivity is neither a general property of the cognitive system nor a property of the brain in encoding letters. Rather, it is a variant and idiosyncratic characteristic of some languages, mostly European, reflecting a strategy of optimizing encoding resources, given the specific structure of words. Since the main goal of reading research is to develop theories that describe the fundamental and invariant phenomena of reading across orthographies, an alternative approach to model visual word recognition is offered. The dimensions of a possible universal model of reading, which outlines the common cognitive operations involved in orthographic processing in all writing systems, are discussed.

  9. Towards a Universal Model of Reading

    PubMed Central

    Frost, Ram

    2013-01-01

    In the last decade, reading research has seen a paradigmatic shift. A new wave of computational models of orthographic processing that offer various forms of noisy position or context-sensitive coding, have revolutionized the field of visual word recognition. The influx of such models stems mainly from consistent findings, coming mostly from European languages, regarding an apparent insensitivity of skilled readers to letter-order. Underlying the current revolution is the theoretical assumption that the insensitivity of readers to letter order reflects the special way in which the human brain encodes the position of letters in printed words. The present paper discusses the theoretical shortcomings and misconceptions of this approach to visual word recognition. A systematic review of data obtained from a variety of languages demonstrates that letter-order insensitivity is not a general property of the cognitive system, neither it is a property of the brain in encoding letters. Rather, it is a variant and idiosyncratic characteristic of some languages, mostly European, reflecting a strategy of optimizing encoding resources, given the specific structure of words. Since the main goal of reading research is to develop theories that describe the fundamental and invariant phenomena of reading across orthographies, an alternative approach to model visual word recognition is offered. The dimensions of a possible universal model of reading, which outlines the common cognitive operations involved in orthographic processing in all writing systems, are discussed. PMID:22929057

  10. Mesoscopic Modeling of Blood Clotting: Coagulation Cascade and Platelets Adhesion

    NASA Astrophysics Data System (ADS)

    Yazdani, Alireza; Li, Zhen; Karniadakis, George

    2015-11-01

    The process of clot formation and growth at a site on a blood vessel wall involve a number of multi-scale simultaneous processes including: multiple chemical reactions in the coagulation cascade, species transport and flow. To model these processes we have incorporated advection-diffusion-reaction (ADR) of multiple species into an extended version of Dissipative Particle Dynamics (DPD) method which is considered as a coarse-grained Molecular Dynamics method. At the continuum level this is equivalent to the Navier-Stokes equation plus one advection-diffusion equation for each specie. The chemistry of clot formation is now understood to be determined by mechanisms involving reactions among many species in dilute solution, where reaction rate constants and species diffusion coefficients in plasma are known. The role of blood particulates, i.e. red cells and platelets, in the clotting process is studied by including them separately and together in the simulations. An agonist-induced platelet activation mechanism is presented, while platelets adhesive dynamics based on a stochastic bond formation/dissociation process is included in the model.

  11. Hybrid Model for Cascading Outage in a Power System: A Numerical Study

    NASA Astrophysics Data System (ADS)

    Susuki, Yoshihiko; Takatsuji, Yu; Hikihara, Takashi

    Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of flows describing swing dynamics with switching rules that are based on protection operation. This paper refers to data on a cascading outage in the September 2003 blackout in Italy and shows a hybrid dynamical system by which propagation of outages reproduced is consistent with the data. This result suggests that hybrid dynamical systems can provide an effective model for the analysis of cascading outages in power systems.

  12. Extending the Compensatory Model of Second Language Reading

    ERIC Educational Resources Information Center

    McNeil, Levi

    2012-01-01

    Bernhardt (2005) proposed a compensatory model of second language reading. This model predicted that 50% of second language (L2) reading scores are attributed to second language knowledge and first-language (L1) reading ability. In this model, these two factors compensate for deficiencies in each other. Although this model explains a significant…

  13. The critical tension in the Cascading DGP model

    SciTech Connect

    Sbisà, Fulvio; Koyama, Kazuya E-mail: kazuya.koyama@port.ac.uk

    2014-09-01

    We study the behaviour of weak gravitational fields in the 6D Cascading DGP model using a bulk-based approach. To deal with the ambiguity in the thin limit of branes of codimension higher than one, we consider a specific regularization of the internal structure of the branes where the 5D brane can be considered thin with respect to the 4D one. We consider the solutions corresponding to pure tension sources on the 4D brane, and study perturbations at first order around these background solutions. We adopt a 4D scalar-vector-tensor decomposition, and focus on the scalar sector of perturbations. We show that, in a suitable 4D limit, the trace part of the 4D metric perturbations obeys a decoupled equation which suggests that it is a ghost for background tensions smaller than a critical tension, while it is a healthy field otherwise. We give a geometrical interpretation of the existence of the critical tension and of the reason why the relevant field is a ghost or not depending on the background tension. We however find a value of the critical tension which is different from the one already found in the literature. Differently from the results in the literature, our analysis implies that, choosing the background tension suitably, we can construct ghost-free models for any value of the free parameters of the theory. We suggest that the difference lies in the procedure used to evaluate the pillbox integration across the codimension-2 brane. We confirm the validity of our analysis by performing numerically the integration in a particular case where the solution inside the thick cod-2 brane is known exactly. We stress that the singular structure of the perturbation fields in the nested branes set-ups is very subtle, and that great care has to be taken when deriving the codimension-2 junction conditions.

  14. The Minimalist Reading Model: Rethinking Reading Lists in Arts and Education Subjects

    ERIC Educational Resources Information Center

    Piscioneri, Matthew; Hlavac, Jim

    2013-01-01

    Despite reading being recognized as a core academic skill, surprisingly little research has been undertaken into university lecture reading requirements. This article reports on the trial and evaluation of a minimalist reading model developed for students in arts and education subjects. Comprising annotated extracts from full texts…

  15. Talking about Reading as Thinking: Modeling the Hidden Complexities of Online Reading Comprehension

    ERIC Educational Resources Information Center

    Coiro, Julie

    2011-01-01

    This article highlights four cognitive processes key to online reading comprehension and how one might begin to transform existing think-aloud strategy models to encompass the challenges of reading for information on the Internet. Informed by principles of cognitive apprenticeship and an emerging taxonomy of online reading comprehension…

  16. Modeling self-sustained activity cascades in socio-technical networks

    NASA Astrophysics Data System (ADS)

    Piedrahita, P.; Borge-Holthoefer, J.; Moreno, Y.; Arenas, A.

    2013-11-01

    The ability to understand and eventually predict the emergence of information and activation cascades in social networks is core to complex socio-technical systems research. However, the complexity of social interactions makes this a challenging enterprise. Previous works on cascade models assume that the emergence of this collective phenomenon is related to the activity observed in the local neighborhood of individuals, but do not consider what determines the willingness to spread information in a time-varying process. Here we present a mechanistic model that accounts for the temporal evolution of the individual state in a simplified setup. We model the activity of the individuals as a complex network of interacting integrate-and-fire oscillators. The model reproduces the statistical characteristics of the cascades in real systems, and provides a framework to study the time evolution of cascades in a state-dependent activity scenario.

  17. Model Programs: Reading. Remedial Reading Program, Pojoaque, New Mexico.

    ERIC Educational Resources Information Center

    American Institutes for Research in the Behavioral Sciences, Palo Alto, CA.

    The elementary school in Pojoaque, New Mexico, has recently developed a remedial reading program for children in grades 2 to 4. Eighty-three children participated in 1969-70. As the population of the area is 76 percent Spanish-American, 12 percent Indian, 12 percent white, and less than 1 percent black, work in the program focuses on language and…

  18. Optimization of cascade-resilient electrical infrastructures and its validation by power flow modeling.

    PubMed

    Fang, Yiping; Pedroni, Nicola; Zio, Enrico

    2015-04-01

    Large-scale outages on real-world critical infrastructures, although infrequent, are increasingly disastrous to our society. In this article, we are primarily concerned with power transmission networks and we consider the problem of allocation of generation to distributors by rewiring links under the objectives of maximizing network resilience to cascading failure and minimizing investment costs. The combinatorial multiobjective optimization is carried out by a nondominated sorting binary differential evolution (NSBDE) algorithm. For each generators-distributors connection pattern considered in the NSBDE search, a computationally cheap, topological model of failure cascading in a complex network (named the Motter-Lai [ML] model) is used to simulate and quantify network resilience to cascading failures initiated by targeted attacks. The results on the 400 kV French power transmission network case study show that the proposed method allows us to identify optimal patterns of generators-distributors connection that improve cascading resilience at an acceptable cost. To verify the realistic character of the results obtained by the NSBDE with the embedded ML topological model, a more realistic but also more computationally expensive model of cascading failures is adopted, based on optimal power flow (namely, the ORNL-Pserc-Alaska) model). The consistent results between the two models provide impetus for the use of topological, complex network theory models for analysis and optimization of large infrastructures against cascading failure with the advantages of simplicity, scalability, and low computational cost.

  19. Testing bedrock incision models: Holocene channel evolution, High Cascades, Oregon

    NASA Astrophysics Data System (ADS)

    Sweeney, K. E.; Roering, J. J.; Fonstad, M. A.

    2013-12-01

    There is abundant field evidence that sediment supply controls the incision of bedrock channels by both protecting the bed from incision and providing tools to incise the bed. Despite several theoretical models for sediment-dependent bedrock abrasion, many investigations of natural channel response to climatic, lithologic, or tectonic forcing rely on the stream power model, which does not consider the role of sediment. Here, we use a well-constrained fluvial channel cut into a Holocene lava flow in the High Cascades, Oregon to compare incision predictions of the stream power model and of the full physics of theoretical models for saltation-abrasion incision by bedload and suspended load. The blocky andesite of Collier lava flow erupted from Collier Cone ~1500 years ago, paving over the existing landscape and erasing fine-scale landscape dissection. Since the eruption, a 6 km stream channel has been incised into the lava flow. The channel is comprised of three alluvial reaches with sediment deposits up to 2 m thick and two bedrock gorges with incision of up to 8 m, with larger magnitude incision in the upstream gorge. Abraded forms such as flutes are present in both gorges. Given the low magnitude and duration of modern snowmelt flow in the channel, it is likely that much of the incision was driven by sediment-laden outburst floods from the terminus of Collier Glacier, which is situated just upstream of the lava flow and has produced two outburst floods in the past 100 years. This site is well suited for comparing incision models because of the relatively uniform lithology of the lava flow and our ability to constrain the timing and depth of incision using the undissected lava surface above the channel as an initial condition. Using a simple finite difference scheme with airborne-Lidar-derived pre-incision topography as an initial condition, we predict incision in the two gorges through time with both stream power and sediment-dependent models. Field observations

  20. Up and down cascade in a dynamo model: spontaneous symmetry breaking.

    PubMed

    Blanter, E M; Narteau, C; Shnirman, M G; Le Mouël, J L

    1999-05-01

    A multiscale turbulent model of dynamo is proposed. A secondary magnetic field is generated from a primary field by a flow made of turbulent helical vortices (cyclones) of different ranges, and amplified by an up and down cascade mechanism. The model displays symmetry breakings of different ranges although the system construction is completely symmetric. Large-scale symmetry breakings for symmetric conditions of the system evolution are investigated for all kinds of cascades: pure direct cascade, pure inverse cascade, and up and down cascade. It is shown that long lived symmetry breakings of high scales can be obtained only in the case of the up and down cascade. The symmetry breakings find expression in intervals of constant polarity of the secondary field (called chrons of the geomagnetic field). Long intervals of constant polarity with quick reversals are obtained in the model; conditions for such a behavior are investigated. Strong variations of the generated magnetic field during intervals of constant polarity are also observed in the model. Possible applications of the model to geodynamo modeling and various directions of future investigation are briefly discussed.

  1. Exploring the link between emotional and behavioral dysregulation: a test of the emotional cascade model.

    PubMed

    Tuna, Ezgi; Bozo, Özlem

    2014-01-01

    The emotional cascade model (Selby, Anestis, & Joiner, 2008) posits that the link between emotional and behavioral dysregulation may be through emotional cascades, which are repetitive cycles of rumination and negative affect that result in an intensification of emotional distress. Dysregulated behaviors, such as non-suicidal self-injury, are used to reduce aversive emotions and distract the person from ruminative processes. The aim of the present study was to investigate the emotional cascade model in a non-Western sample of Turkish university students. Accordingly, a structural equation model was tested, and the results demonstrated that the emotional cascades were indeed associated to dysregulated behaviors, even when the effect of current symptoms of depression and anxiety on behavioral dysregulation was statistically controlled. Furthermore, thought suppression had a stronger relationship with all symptom patterns as compared to rumination, which may point to a cultural difference. Possible implications of the findings are discussed.

  2. Simulation Modeling of an Enhanced Low-Emission Swirl-Cascade Burner

    SciTech Connect

    Ala Qubbaj

    2004-09-01

    ''Cascade-burners'' is a passive technique to control the stoichiometry of the flame through changing the flow dynamics and rates of mixing in the combustion zone with a set of venturis surrounding the flame. Cascade-burners have shown advantages over other techniques; its reliability, flexibility, safety, and cost makes it more attractive and desirable. On the other hand, the application of ''Swirl-burners'' has shown superiority in producing a stable flame under a variety of operating conditions and fuel types. The basic idea is to impart swirl to the air or fuel stream, or both. This not only helps to stabilize the flame but also enhances mixing in the combustion zone. As a result, nonpremixed (diffusion) swirl burners have been increasingly used in industrial combustion systems such as gas turbines, boilers, and furnaces, due to their advantages of safety and stability. Despite the advantages of cascade and swirl burners, both are passive control techniques, which resulted in a moderate pollutant emissions reduction compared to SCR, SNCR and FGR (active) methods. The present investigation will study the prospects of combining both techniques in what to be named as ''an enhanced swirl-cascade burner''. Natural gas jet diffusion flames in baseline, cascade, swirl, and swirl-cascade burners were numerically modeled using CFDRC package. The thermal, composition, and flow (velocity) fields were simulated. The numerical results showed that swirl and cascade burners have a more efficient fuel/air mixing, a shorter flame, and a lower NOx emission levels, compared to the baseline case. The results also revealed that the optimal configurations of the cascaded and swirling flames have not produced an improved performance when combined together in a ''swirl-cascade burner''. The non-linearity and complexity of the system accounts for such a result, and therefore, all possible combinations, i.e. swirl numbers (SN) versus venturi diameter ratios (D/d), need to be considered.

  3. Toward Modeling Reading Comprehension and Reading Fluency in English Language Learners

    ERIC Educational Resources Information Center

    Yaghoub Zadeh, Zohreh; Farnia, Fataneh; Geva, Esther

    2012-01-01

    This study investigated the adequacy of an expanded simple view of reading (SVR) framework for English language learners (ELLs), using mediation modeling approach. The proposed expanded SVR included reading fluency as an outcome and phonological awareness and naming speed as predictors. To test the fit of the proposed mediation model, longitudinal…

  4. Multifractal-cascade model for inertial and dissipation ranges based on the wavelet reconstruction method

    NASA Astrophysics Data System (ADS)

    Zhou, Long; Rauh, Cornelia; Delgado, Antonio

    2015-07-01

    The discrete wavelet is introduced to construct the turbulent velocity fields. The simple binary cascade model p model is served as the inertial range model for velocity increments. The dissipation model, which follows Foias et al. [Phys. Fluids A 2, 464 (1990), 10.1063/1.857744] takes the form of exp(-g k ) . The length of inertial and dissipation ranges is computed according to the different construction levels. Based on the binary cascade theory and the proposed dissipation model, the Reynolds number regarding to the cascade process can be estimated. The dissipation rate calculated from the proposed model not only agrees with the existing experiment data, but also suggests that the dissipation rate is not an independent variable with respect to the Reynolds number.

  5. Does Writing Modeled after Children's Picture Books Improve Reading Comprehension?

    ERIC Educational Resources Information Center

    Whitmer, Jean E.

    A study examined whether writing modeled from children's picture books would improve reading comprehension of fourth and fifth graders as much as traditional skills instruction. Subjects, 69 children reading at least one year below grade level from six Chapter 1 Colorado schools, were pretested for reading comprehension levels. Subjects were then…

  6. Universal resilience patterns in cascading load model: More capacity is not always better

    NASA Astrophysics Data System (ADS)

    Wang, Jianwei; Wang, Xue; Cai, Lin; Ni, Chengzhang; Xie, Wei; Xu, Bo

    We study the problem of universal resilience patterns in complex networks against cascading failures. We revise the classical betweenness method and overcome its limitation of quantifying the load in cascading model. Considering that the generated load by all nodes should be equal to the transported one by all edges in the whole network, we propose a new method to quantify the load on an edge and construct a simple cascading model. By attacking the edge with the highest load, we show that, if the flow between two nodes is transported along the shortest paths between them, then the resilience of some networks against cascading failures inversely decreases with the enhancement of the capacity of every edge, i.e. the more capacity is not always better. We also observe the abnormal fluctuation of the additional load that exceeds the capacity of each edge. By a simple graph, we analyze the propagation of cascading failures step by step, and give a reasonable explanation of the abnormal fluctuation of cascading dynamics.

  7. SIMULATION MODELING OF AN ENHANCED LOW-EMISSION SWIRL-CASCADE BURNER

    SciTech Connect

    Ala Qubbaj

    2003-04-01

    The research team was formed. The advanced CFDRC-CHEMKIN software package was installed on a SUN-SPARC dual processor workstation. The literature pertinent to the project was collected. The physical model was set and all parameters and variables were identified. Based on the physical model, the geometric modeling and grid generation processes were performed using the CFD-GEOM (Interactive Geometric Modeling and Grid Generation software). A total number of 11160 cells (248 x 45) were generated to numerically model the baseline, cascaded, swirling, and swirling-cascaded flames. With the cascade being added to the jet, the geometric complexity of the problem increased; which required multi-domain structured grid systems to be connected and matched on the boundaries.

  8. An evolutionary cascade model for sauropod dinosaur gigantism--overview, update and tests.

    PubMed

    Sander, P Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.

  9. An Evolutionary Cascade Model for Sauropod Dinosaur Gigantism - Overview, Update and Tests

    PubMed Central

    Sander, P. Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades (“Reproduction”, “Feeding”, “Head and neck”, “Avian-style lung”, and “Metabolism”). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait “Very high body mass”. Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size. PMID:24205267

  10. Analysis of car-following model with cascade compensation strategy

    NASA Astrophysics Data System (ADS)

    Zhu, Wen-Xing; Zhang, Li-Dong

    2016-05-01

    Cascade compensation mechanism was designed to improve the dynamical performance of traffic flow system. Two compensation methods were used to study unit step response in time domain and frequency characteristics with different parameters. The overshoot and phase margins are proportional to the compensation parameter in an underdamped condition. Through the comparison we choose the phase-lead compensation method as the main strategy in suppressing the traffic jam. The simulations were conducted under two boundary conditions to verify the validity of the compensator. The conclusion can be drawn that the stability of the system is strengthened with increased phase-lead compensation parameter. Moreover, the numerical simulation results are in good agreement with analytical results.

  11. Multidimensional infinitely divisible cascades. Application to the modelling of intermittency in turbulence

    NASA Astrophysics Data System (ADS)

    Chainais, P.

    2006-05-01

    The framework of infinitely divisible scaling was first developed to analyse the statistical intermittency of turbulence in fluid dynamics. It also reveals a powerful tool to describe and model various situations including Internet traffic, financial time series, textures ... A series of recent works introduced the infinitely divisible cascades in 1 dimension, a family of multifractal processes that can be easily synthesized numerically. This work extends the definition of infinitely divisible cascades from 1 dimension to d dimensions in the scalar case. Thus, a class of models is proposed both for data analysis and for numerical simulation in dimension d≥1. In this article, we give the definitions and main properties of infinitely divisible cascades in d dimensions. Then we focus on the modelling of statistical intermittency in turbulent flows. Several other applications are considered.

  12. Cascading failures coupled model of interdependent double layered public transit network

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Fu, Bai-Bai; Li, Shu-Bin

    2016-06-01

    Taking urban public transit network as research perspective, this work introduces the influences of adjacent stations on definition of station initial load, the connected edge transit capacity, and the coupled capacity to modify traditional load-capacity cascading failures (CFs) model. Furthermore, we consider the coupled effect of lower layered public transit network on the CFs of upper layered public transit network, and construct CFs coupled model of double layered public transit network with “interdependent relationship”. Finally, taking Jinan city’s public transit network as example, we give the dynamics simulation analysis of CFs under different control parameters based on measurement indicator of station cascading failures ratio (abbreviated as CF) and the scale of time-step cascading failures (abbreviated as TCFl), get the influencing characteristics of various control parameters, and verify the feasibility of CFs coupled model of double layered public transit network.

  13. Modeling the dental development of fossil hominins through the inhibitory cascade

    PubMed Central

    Schroer, Kes; Wood, Bernard

    2015-01-01

    The inhibitory cascade is a mathematical model for interpreting the relative size of the occlusal surfaces of mammalian molars in terms of developmental mechanisms. The cascade is derived from experimental studies of mouse molars developed in culture, and has been tested and applied to the dentitions of rodents, ungulates, carnivores, and platyrrhines. Results from such applications have provided new information regarding the origins of plesiomorphic traits in mammalian clade and how derived morphologies may arise. In this study we apply the inhibitory cascade model to the postcanine dentition of a sample of Old World primates that includes fossil hominins. The results of this study suggest that the inhibitory cascade (i.e. M1 < M2 < M3) describes the relative sizes of the molar occlusal areas of Old World primates and is likely the plesiomorphic condition for this clade. Within that clade, whereas most Old World monkeys have a M1 < M2 < M3 pattern, most apes have a M1 < M2 ≈ M3 pattern. This modified cascade suggests that greater levels of inhibition (or less activation) are acting on the posterior molars of apes, thus facilitating the reduction of M3s within the apes. With the exception of the baboon genus Papio, extant congeners typically share the same molar inhibitory cascade. The differences in the relative size relationships observed in the molar and premolar-molar cascades of the species included in the fossil hominin genus Paranthropus suggest that although large postcanine teeth are a shared derived trait within this genus, the developmental basis for postcanine megadontia may not be the same in these two Paranthropus taxa. Our results show that phenotypic characters such as postcanine megadontia may not reflect common development. PMID:25420453

  14. Dynamic modeling of optically pumped electrically driven terahertz quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Hamadou, A.; Thobel, J.-L.; Lamari, S.

    2017-03-01

    Based on our four-level rate equations model, we analyze through numerical simulations the dynamics of the electron density, population inversion and terahertz intensity present within the cavity of a mid-infrared optically pumped electrically driven THz quantum cascade laser. We find in particular that the mid-infrared pump intensity influences significantly the dynamical behavior of the present device. Moreover, compared to its homologue, the conventional electrically injected THz quantum cascade laser, this system presents much faster dynamics. In addition, within the premises of our model, we derive in the most general case the equation that allows for the determination of the turn-on delay time tth.

  15. ARRA: Reconfiguring Power Systems to Minimize Cascading Failures - Models and Algorithms

    SciTech Connect

    Dobson, Ian; Hiskens, Ian; Linderoth, Jeffrey; Wright, Stephen

    2013-12-16

    Building on models of electrical power systems, and on powerful mathematical techniques including optimization, model predictive control, and simluation, this project investigated important issues related to the stable operation of power grids. A topic of particular focus was cascading failures of the power grid: simulation, quantification, mitigation, and control. We also analyzed the vulnerability of networks to component failures, and the design of networks that are responsive to and robust to such failures. Numerous other related topics were investigated, including energy hubs and cascading stall of induction machines

  16. A Lattice Model of the Development of Reading Comprehension.

    PubMed

    Connor, Carol McDonald

    2016-12-01

    In this article, I present a developmental model of how children learn to comprehend what they read, which builds on current models of reading comprehension and integrates findings from instructional research and evidence-based models of development in early and middle childhood. The lattice model holds that children's developing reading comprehension is a function of the interacting, reciprocal, and bootstrapping effects of developing text-specific, linguistic, and social-cognitive processes, which interact with instruction as child-characteristic-by-instruction (CXI) interaction effects. The processes develop over time and in the context of classroom, home, peer, community, and other influences to affect children's development of proficient reading comprehension. I first describe models of reading comprehension. I then review the basic processes in the model, the role of instruction, and CXI interactions in the context of the lattice model. I then discuss implications for instruction and research.

  17. Developing a structural model of reading: the role of hearing status in reading development over time.

    PubMed

    Coppens, Karien M; Tellings, Agnes; Schreuder, Robert; Verhoeven, Ludo

    2013-10-01

    The purpose of the present study was to develop a structural model of reading based on the Lexical Quality Hypothesis (Perfetti & Hart, 2002). Data from a 4-year longitudinal study of Dutch primary school children with and without hearing loss were used to conduct an exploratory analysis of how lexical components (i.e., decoding skills, lexical decision, and lexical use) relate to one another and to reading comprehension. Our structural model supports a positive role of the quality of the mental lexicon for reading comprehension. Furthermore, it was possible to apply the same conceptual model of reading development to both groups of children when incorporating hearing status as a grouping variable. However, a multigroup comparison model showed that the predictive values of the relations between the different tasks differed for the two groups.

  18. Cascades of failures in various models of interdependent networks

    NASA Astrophysics Data System (ADS)

    Buldyrev, Sergey; Kadish, Benjamin; Shere, Nathaniel; Aharon, Mitchel; Cwilich, Gabriel

    2012-02-01

    Complex networks appear in almost every aspect of science and technology. Recently an analytical framework for studying the percolation properties of interacting networks has been developed [1]. These studies however have several limitations. The real networks do are not randomly connected. They are often embedded into two dimensional space. The dependency links are not connecting nodes at random but have tendency to connect nodes with similar degrees, or nodes which are close to each other in Euclidian space. Moreover, the network failures may occur not only to the loss of connectivity but also due to overload of nodes with high betweennes. We have study these situations analytically and by computer simulations and found the conditions at which networks collapse in an abrupt first order like transition when the entire network becomes non-functional or fail gradually like in a second order transition as a greater fraction of nodes is removed in the initial attack or failure. [4pt] [1] S. V. Buldyrev, R. Parshani, G. Paul, H. E. Stanley, and S. Havlin, ``Catastrophic cascade of failures in interdependent networks,'' Nature 464, 1025-1028 (2010)

  19. Reading.

    ERIC Educational Resources Information Center

    Mulford, Jeremy, Ed.

    1971-01-01

    A collection of articles reflecting the underlying concern of British contributors with continuity--conceiving reading and learning as a whole throughout the school years--comprises this special issue of "English in Education." Specific topics treated are: "What Children Learn in Learning to Read" by R. Morris; "Reading without Primers" by W.…

  20. A MODEL PROGRAM FOR REMEDIAL READING.

    ERIC Educational Resources Information Center

    CUTTS, WARREN G.

    WHENEVER IT BECOMES NECESSARY FOR A PUPIL TO RECEIVE EXTRA HELP OUTSIDE THE REGULAR CLASSROOM, HE IS INVOLVED IN REMEDIAL READING. REMEDIAL INSTRUCTION IS MORE HIGHLY INDIVIDUALIZED THAN REGULAR READING INSTRUCTION, AND IS TAILORED TO INDIVIDUAL NEEDS ON THE BASIS OF DIAGNOSTIC TESTING. MOTIVATION IS IMPORTANT TO ALL REMEDIAL INSTRUCTION, FOR…

  1. Developing a Model of Teaching Reading Comprehension for EFL Students

    ERIC Educational Resources Information Center

    Hamra, Arifuddin; Syatriana, Eny

    2010-01-01

    This study aimed at designing a model of teaching reading comprehension based on the objectives of teaching reading at the senior high school and the teachers' understanding of the school curriculum and to describe the implementation of the model. The subject consisted of 24 teachers, 167 students of five SMAs (senior high schools) in South…

  2. Does the PMSP Connectionist Model of Single Word Reading Learn to Read in the Same Way as a Child?

    ERIC Educational Resources Information Center

    Powell, Daisy; Plaut, David; Funnell, Elaine

    2006-01-01

    The Plaut, McClelland, Seidenberg and Patterson (1996) connectionist model of reading was evaluated at two points early in its training against reading data collected from British children on two occasions during their first year of literacy instruction. First, the network's non-word reading was poor relative to word reading when compared with the…

  3. Density matrix model for polarons in a terahertz quantum dot cascade laser

    NASA Astrophysics Data System (ADS)

    Burnett, Benjamin A.; Williams, Benjamin S.

    2014-10-01

    A density matrix based method is introduced for computation of steady-state dynamics in quantum cascade systems of arbitrary size, which incorporates an optical field coherently. The method is applied to a model terahertz quantum dot cascade laser system, where a means of treating coherent electron-optical-phonon coupling is also introduced. Results predict a strong increase in the upper state lifetime and operating temperature as compared to traditional well-based terahertz quantum cascade lasers. However, new complications also arise, including multiple peaks in the gain spectrum due to strong electron-phonon coupling, and strong parasitic subthreshold current channels that arise due to reduced dephasing. It is anticipated that novel design schemes will be necessary for such lasers to become a reality.

  4. Cascading failures in bi-partite graphs: model for systemic risk propagation.

    PubMed

    Huang, Xuqing; Vodenska, Irena; Havlin, Shlomo; Stanley, H Eugene

    2013-01-01

    As economic entities become increasingly interconnected, a shock in a financial network can provoke significant cascading failures throughout the system. To study the systemic risk of financial systems, we create a bi-partite banking network model composed of banks and bank assets and propose a cascading failure model to describe the risk propagation process during crises. We empirically test the model with 2007 US commercial banks balance sheet data and compare the model prediction of the failed banks with the real failed banks after 2007. We find that our model efficiently identifies a significant portion of the actual failed banks reported by Federal Deposit Insurance Corporation. The results suggest that this model could be useful for systemic risk stress testing for financial systems. The model also identifies that commercial rather than residential real estate assets are major culprits for the failure of over 350 US commercial banks during 2008-2011.

  5. Cascading Failures in Bi-partite Graphs: Model for Systemic Risk Propagation

    PubMed Central

    Huang, Xuqing; Vodenska, Irena; Havlin, Shlomo; Stanley, H. Eugene

    2013-01-01

    As economic entities become increasingly interconnected, a shock in a financial network can provoke significant cascading failures throughout the system. To study the systemic risk of financial systems, we create a bi-partite banking network model composed of banks and bank assets and propose a cascading failure model to describe the risk propagation process during crises. We empirically test the model with 2007 US commercial banks balance sheet data and compare the model prediction of the failed banks with the real failed banks after 2007. We find that our model efficiently identifies a significant portion of the actual failed banks reported by Federal Deposit Insurance Corporation. The results suggest that this model could be useful for systemic risk stress testing for financial systems. The model also identifies that commercial rather than residential real estate assets are major culprits for the failure of over 350 US commercial banks during 2008–2011. PMID:23386974

  6. Temperament Pathways to Childhood Disruptive Behavior and Adolescent Substance Abuse: Testing a Cascade Model

    ERIC Educational Resources Information Center

    Martel, Michelle M.; Pierce, Laura; Nigg, Joel T.; Jester, Jennifer M.; Adams, Kenneth; Puttler, Leon I.; Buu, Anne; Fitzgerald, Hiram; Zucker, Robert A.

    2009-01-01

    Temperament traits may increase risk for developmental psychopathology like Attention-Deficit/Hyperactivity Disorder (ADHD) and disruptive behaviors during childhood, as well as predisposing to substance abuse during adolescence. In the current study, a cascade model of trait pathways to adolescent substance abuse was examined. Component…

  7. Cumulative Risk Disparities in Children's Neurocognitive Functioning: A Developmental Cascade Model

    ERIC Educational Resources Information Center

    Wade, Mark; Browne, Dillon T.; Plamondon, Andre; Daniel, Ella; Jenkins, Jennifer M.

    2016-01-01

    The current longitudinal study examined the role of cumulative social risk on children's theory of mind (ToM) and executive functioning (EF) across early development. Further, we also tested a cascade model of development in which children's social cognition at 18 months was hypothesized to predict ToM and EF at age 4.5 through intermediary…

  8. Using the Cascade Model to Improve Antenatal Screening for the Hemoglobin Disorders

    ERIC Educational Resources Information Center

    Gould, Dinah; Papadopoulos, Irena; Kelly, Daniel

    2012-01-01

    Introduction: The inherited hemoglobin disorders constitute a major public health problem. Facilitators (experienced hemoglobin counselors) were trained to deliver knowledge and skills to "frontline" practitioners to enable them to support parents during antenatal screening via a cascade (train-the-trainer) model. Objectives of…

  9. The Transfer of Content Knowledge in a Cascade Model of Professional Development

    ERIC Educational Resources Information Center

    Turner, Fay; Brownhill, Simon; Wilson, Elaine

    2017-01-01

    A cascade model of professional development presents a particular risk that "knowledge" promoted in a programme will be diluted or distorted as it passes from originators of the programme to local trainers and then to the target teachers. Careful monitoring of trainers' and teachers' knowledge as it is transferred through the system is…

  10. SPATIAL FOREST SOIL PROPERTIES FOR ECOLOGICAL MODELING IN THE WESTERN OREGON CASCADES

    EPA Science Inventory

    The ultimate objective of this work is to provide a spatially distributed database of soil properties to serve as inputs to model ecological processes in western forests at the landscape scale. The Central Western Oregon Cascades are rich in biodiversity and they are a fascinati...

  11. Modeling cascading failures with the crisis of trust in social networks

    NASA Astrophysics Data System (ADS)

    Yi, Chengqi; Bao, Yuanyuan; Jiang, Jingchi; Xue, Yibo

    2015-10-01

    In social networks, some friends often post or disseminate malicious information, such as advertising messages, informal overseas purchasing messages, illegal messages, or rumors. Too much malicious information may cause a feeling of intense annoyance. When the feeling exceeds a certain threshold, it will lead social network users to distrust these friends, which we call the crisis of trust. The crisis of trust in social networks has already become a universal concern and an urgent unsolved problem. As a result of the crisis of trust, users will cut off their relationships with some of their untrustworthy friends. Once a few of these relationships are made unavailable, it is likely that other friends will decline trust, and a large portion of the social network will be influenced. The phenomenon in which the unavailability of a few relationships will trigger the failure of successive relationships is known as cascading failure dynamics. To our best knowledge, no one has formally proposed cascading failures dynamics with the crisis of trust in social networks. In this paper, we address this potential issue, quantify the trust between two users based on user similarity, and model the minimum tolerance with a nonlinear equation. Furthermore, we construct the processes of cascading failures dynamics by considering the unique features of social networks. Based on real social network datasets (Sina Weibo, Facebook and Twitter), we adopt two attack strategies (the highest trust attack (HT) and the lowest trust attack (LT)) to evaluate the proposed dynamics and to further analyze the changes of the topology, connectivity, cascading time and cascade effect under the above attacks. We numerically find that the sparse and inhomogeneous network structure in our cascading model can better improve the robustness of social networks than the dense and homogeneous structure. However, the network structure that seems like ripples is more vulnerable than the other two network

  12. Phonology, reading acquisition, and dyslexia: insights from connectionist models.

    PubMed

    Harm, M W; Seidenberg, M S

    1999-07-01

    The development of reading skill and bases of developmental dyslexia were explored using connectionist models. Four issues were examined: the acquisition of phonological knowledge prior to reading, how this knowledge facilitates learning to read, phonological and nonphonological bases of dyslexia, and effects of literacy on phonological representation. Compared with simple feedforward networks, representing phonological knowledge in an attractor network yielded improved learning and generalization. Phonological and surface forms of developmental dyslexia, which are usually attributed to impairments in distinct lexical and nonlexical processing "routes," were derived from different types of damage to the network. The results provide a computationally explicit account of many aspects of reading acquisition using connectionist principles.

  13. Reading and a Diffusion Model Analysis of Reaction Time

    PubMed Central

    Naples, Adam; Katz, Leonard; Grigorenko, Elena L.

    2012-01-01

    Processing speed is associated with reading performance. However, the literature is not clear either on the definition of processing speed or on why and how it contributes to reading performance. In this study we demonstrated that processing speed, as measured by reaction time, is not a unitary construct. Using the diffusion model of two-choice reaction time, we assessed processing speed in a series of same-different reaction time tasks for letter and number strings. We demonstrated that the association between reaction time and reading performance is driven by processing speed for reading-related information, but not motor or sensory encoding speed. PMID:22612543

  14. CASCADER: An m-chain gas-phase radionuclide transport and fate model. Volume 2, User`s manual for CASCADR8

    SciTech Connect

    Cawlfield, D.E.; Been, K.B.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-06-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. This is volume two to the CASCADER series, titled CASCADR8. It embodies the concepts presented in volume one of this series. To properly understand how the CASCADR8 model works, the reader should read volume one first. This volume presents the input and output file structure for CASCADR8, and a set of realistic scenarios for buried sources of radon gas.

  15. Incorporating RTI in a Hybrid Model of Reading Disability

    ERIC Educational Resources Information Center

    Spencer, Mercedes; Wagner, Richard K.; Schatschneider, Christopher; Quinn, Jamie M.; Lopez, Danielle; Petscher, Yaacov

    2014-01-01

    The present study seeks to evaluate a hybrid model of identification that incorporates response to instruction and intervention (RTI) as one of the key symptoms of reading disability. The 1-year stability of alternative operational definitions of reading disability was examined in a large-scale sample of students who were followed longitudinally…

  16. A Cascade Model Connecting Life Stress to Risk Behavior Among Rural African American Emerging Adults

    PubMed Central

    Brody, Gene H.; Chen, Yi-fu; Kogan, Steven M.

    2010-01-01

    A 3-wave cascade model linking life stress to increases in risk behavior was tested with 347 African American emerging adults living in the rural South. Data analyses using structural equation modeling and latent growth curve modeling demonstrated that life stress was linked to increases in risk behavior as African Americans transitioned out of secondary school. The cascade model indicated that life stress fostered increases in negative emotions. Negative emotions, in turn, were linked to increases in affiliations with deviant peers and romantic partners; this forecast increases in risk behavior. The findings supported a stress proliferation framework, in which primary stressors affect increases in secondary stressors that carry forward to influence changes in risk behaviors that can potentially compromise mental health. PMID:20576186

  17. Lumley's energy cascade dissipation rate model for boundary-free turbulent shear flows

    NASA Technical Reports Server (NTRS)

    Duncan, B. S.

    1992-01-01

    True dissipation occurs mainly at the highest wavenumbers where the eddy sizes are comparatively small. These high wavenumbers receive their energy through the spectral cascade of energy starting with the largest eddies spilling energy into the smaller eddies, passing through each wavenumber until it is dissipated at the microscopic scale. However, a small percentage of the energy does not spill continuously through the cascade but is instantly passed to the higher wavenumbers. Consequently, the smallest eddies receive a certain amount of energy almost immediately. As the spectral energy cascade continues, the highest wavenumber needs a certain time to receive all the energy which has been transferred from the largest eddies. As such, there is a time delay, of the order of tau, between the generation of energy by the largest eddies and the eventual dissipation of this energy. For equilibrium turbulence at high Reynolds numbers, there is a wide range where energy is neither produced by the large eddies nor dissipated by viscosity, but is conserved and passed from wavenumber to higher wavenumbers. The rate at which energy cascades from one wavenumber to another is proportional to the energy contained within that wavenumber. This rate is constant and has been used in the past as a dissipation rate of turbulent kinetic energy. However, this is true only in steady, equilibrium turbulence. Most dissipation models contend that the production of dissipation is proportional to the production of energy and that the destruction of dissipation is proportional to the destruction of energy. In essence, these models state that the change in the dissipation rate is proportional to the change in the kinetic energy. This assumption is obviously incorrect for the case where there is no production of turbulent energy, yet energy continues to cascade from large to small eddies. If the time lag between the onset on the energy cascade to the destruction of energy at the microscale can be

  18. Glacier modeling in support of field observations of mass balance at South Cascade Glacier, Washington, USA

    USGS Publications Warehouse

    Josberger, Edward G.; Bidlake, William R.

    2010-01-01

    The long-term USGS measurement and reporting of mass balance at South Cascade Glacier was assisted in balance years 2006 and 2007 by a new mass balance model. The model incorporates a temperature-index melt computation and accumulation is modeled from glacier air temperature and gaged precipitation at a remote site. Mass balance modeling was used with glaciological measurements to estimate dates and magnitudes of critical mass balance phenomena. In support of the modeling, a detailed analysis was made of the "glacier cooling effect" that reduces summer air temperature near the ice surface as compared to that predicted on the basis of a spatially uniform temperature lapse rate. The analysis was based on several years of data from measurements of near-surface air temperature on the glacier. The 2006 and 2007 winter balances of South Cascade Glacier, computed with this new, model-augmented methodology, were 2.61 and 3.41 mWE, respectively. The 2006 and 2007 summer balances were -4.20 and -3.63 mWE, respectively, and the 2006 and 2007 net balances were -1.59 and -0.22 mWE. PDF version of a presentation on the mass balance of South Cascade Glacier in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.

  19. Distributed energy balance modeling of South Cascade Glacier, Washington and assessment of model uncertainty

    USGS Publications Warehouse

    Anslow, Faron S.; Hostetler, S.; Bidlake, W.R.; Clark, P.U.

    2008-01-01

    We have developed a physically based, distributed surface energy balance model to simulate glacier mass balance under meteorological and climatological forcing. Here we apply the model to estimate summer ablation on South Cascade Glacier, Washington, for the 2004 and 2005 mass balance seasons. To arrive at optimal mass balance simulations, we investigate and quantify model uncertainty associated with selecting from a range of physical parameter values that are not commonly measured in glaciological mass balance field studies. We optimize the performance of the model by varying values for atmospheric transmissivity, the albedo of surrounding topography, precipitation-elevation lapse rate, surface roughness for turbulent exchange of momentum, and snow albedo aging coefficient. Of these the snow aging parameter and precipitation lapse rates have the greatest influence on the modeled ablation. We examined model sensitivity to varying parameters by performing an additional 103 realizations with parameters randomly chosen over a ??5% range centered about the optimum values. The best fit suite of model parameters yielded a net balance of -1.69??0.38 m water equivalent (WE) for the 2004 water year and -2.10??0.30 m WE up to 11 September 2005. The 2004 result is within 3% of the measured value. These simulations account for 91% and 93% of the variance in measured ablation for the respective years. Copyright 2008 by the American Geophysical Union.

  20. Integrated snow and hydrology modeling for climate change impact assessment in Oregon Cascades

    NASA Astrophysics Data System (ADS)

    Safeeq, M.; Grant, G.; Lewis, S.; Nolin, A. W.; Hempel, L. A.; Cooper, M.; Tague, C.

    2014-12-01

    In the Pacific Northwest (PNW), increasing temperatures are expected to alter the hydrologic regimes of streams by shifting precipitation from snow to rain and forcing earlier snowmelt. How are such changes likely to affect peak flows across the region? Shifts in peak flows have obvious implications for changing flood risk, but are also likely to affect channel morphology, sediment transport, aquatic habitat, and water quality, issues with potentially high economic and environmental cost. Our goal, then, is to rigorously evaluate sensitivity to potential peak flow changes across the PNW. We address this by developing a detailed representation of snowpack and streamflow evolution under varying climate scenarios using a cascade-modeling approach. We have identified paired watersheds located on the east (Metolius River) and west (McKenzie River) sides of the Cascades, representing dry and wet climatic regimes, respectively. The tributaries of these two rivers are comprised of contrasting hydrologic regimes: surface-runoff dominated western cascades and deep-groundwater dominated high-cascades systems. We use a detailed hydro-ecological model (RHESSys) in conjunction with a spatially distributed snowpack evolution model (SnowModel) to characterize the peak flow behavior under present and future climate. We first calibrated and validated the SnowModel using observed temperature, precipitation, snow water equivalent, and manual snow survey data sets. We then employed a multi-objective calibration strategy for RHESSys using the simulated snow accumulation and melt from SnowModel and observed streamflow. The Nash-Sutcliffe Efficiency between observed and simulated streamflow varies between 0.5 in groundwater and 0.71 in surface-runoff dominated systems. The initial results indicate enhanced peak flow under future climate across all basins, but the magnitude of increase varies by the level of snowpack and deep-groundwater contribution in the watershed. Our continuing effort

  1. Hydraulic modeling for lahar hazards at cascades volcanoes

    USGS Publications Warehouse

    Costa, J.E.

    1997-01-01

    The National Weather Service flood routing model DAMBRK is able to closely replicate field-documented stages of historic and prehistoric lahars from Mt. Rainier, Washington, and Mt. Hood, Oregon. Modeled time-of-travel of flow waves are generally consistent with documented lahar travel-times from other volcanoes around the world. The model adequately replicates a range of lahars and debris flows, including the 230 million km3 Electron lahar from Mt. Rainier, as well as a 10 m3 debris flow generated in a large outdoor experimental flume. The model is used to simulate a hypothetical lahar with a volume of 50 million m3 down the East Fork Hood River from Mt. Hood, Oregon. Although a flow such as this is thought to be possible in the Hood River valley, no field evidence exists on which to base a hazards assessment. DAMBRK seems likely to be usable in many volcanic settings to estimate discharge, velocity, and inundation areas of lahars when input hydrographs and energy-loss coefficients can be reasonably estimated.

  2. Comparison of residence time models for cascading rotary dryers

    SciTech Connect

    Cao, W.F.; Langrish, T.A.G.

    1999-04-01

    The predictions of the models of Matchett and Baker (1988), Saeman and Mitchell (1954) and Friedman and Marshall (1949) for the solids residence time in rotary dryers have been compared with both pilot-scale and industrial-scale data. A countercurrent pilot-scale dryer of 0.2m diameter and 2m long has been used with air velocities up to 1.5 m to measure the residence times of sorghum grain. The average discrepancy for the solids residence time between the predictions and the experiments that were carried out in the pilot-scale rotary dryer is {minus}10.4%. Compared with the models of Friedman and Marshall (1949) and Saeman and Mitchell (1954) for the pilot-scale data obtained here, the Matchett and Baker model is more satisfactory for predicting the solids residence time in this pilot-scale dryer. It has also been found that the model of Matchett and Baker describes the industrial data of Saeman and Mitchell (1954) than the correlation of Friedman and Marshall (1949).

  3. Cascaded Network Body Channel Model for Intrabody Communication.

    PubMed

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement.

  4. The Materosion project, a sediment cascade modeling for torrential sediment transfers: final results and perspectives

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Loye, Alexandre; Mazotti, Benoit; Bardou, Eric; Jaboyedoff, Michel

    2013-04-01

    The Materosion project, conducted between the swiss canton of Valais (CREALP) and University of Lausanne (CRET) aims at forecasting sediment transfer in alpine torrents using the sediment cascade concept. The study site is the high Anniviers valley, around the village of Zinal (Valais). The torrents are divided in homogeneous reaches, to and from which sediments are transported by debris flows and bedload transport events. The model runs simulations of 100 years, with a 1-month time step, each with a given a random meteorological event ranging from no activity up to high magnitude debris flows. These events are calibrated using local rain data and observed corresponding debris flow frequencies. The model is applied to ten torrent systems with variable geological context, watershed geometries and sediment supplies. Given the high number of possible event scenarios, 10'000 simulations per torrent are performed, giving a statistical distribution of cumulated volumes and an event size distribution. A way to visualize the complex results data is proposed, and a back-analysis of the internal sediment cascade dynamic is performed. The back-analysis shows that the results' distribution stabilize after ~5'000 simulations. The model results, especially the range of debris flow volumes are crucial to maintain mitigation measures such as retention dams, and give clues for future sediment cascade modeling.

  5. Effects of two-temperature model on cascade evolution in Ni and NiFe

    DOE PAGES

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; ...

    2016-07-05

    We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic effects are more profound in the higher-energy cascades, and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than in Ni.

  6. Critical points and transitions in an electric power transmission model for cascading failure blackouts.

    PubMed

    Carreras, B. A.; Lynch, V. E.; Dobson, I.; Newman, D. E.

    2002-12-01

    Cascading failures in large-scale electric power transmission systems are an important cause of blackouts. Analysis of North American blackout data has revealed power law (algebraic) tails in the blackout size probability distribution which suggests a dynamical origin. With this observation as motivation, we examine cascading failure in a simplified transmission system model as load power demand is increased. The model represents generators, loads, the transmission line network, and the operating limits on these components. Two types of critical points are identified and are characterized by transmission line flow limits and generator capability limits, respectively. Results are obtained for tree networks of a regular form and a more realistic 118-node network. It is found that operation near critical points can produce power law tails in the blackout size probability distribution similar to those observed. The complex nature of the solution space due to the interaction of the two critical points is examined.(c) 2002 American Institute of Physics.

  7. Lumped-equivalent circuit model for multi-stage cascaded magnetoelectric dual-tunable bandpass filter

    NASA Astrophysics Data System (ADS)

    Zhang, Qiu-Shi; Zhu, Feng-Jie; Zhou, Hao-Miao

    2015-10-01

    A lumped-equivalent circuit model of a novel magnetoelectric tunable bandpass filter, which is realized in the form of multi-stage cascading between a plurality of magnetoelectric laminates, is established in this paper for convenient analysis. The multi-stage cascaded filter is degraded to the coupling microstrip filter with only one magnetoelectric laminate and then compared with the existing experiment results. The comparison reveals that the insertion loss curves predicted by the degraded circuit model are in good agreement with the experiment results and the predicted results of the electromagnetic field simulation, thus the validity of the model is verified. The model is then degraded to the two-stage cascaded magnetoelectric filter with two magnetoelectric laminates. It is revealed that if the applied external bias magnetic or electric fields on the two magnetoelectric laminates are identical, then the passband of the filter will drift under the changed external field; that is to say, the filter has the characteristics of external magnetic field tunability and electric field tunability. If the applied external bias magnetic or electric fields on two magnetoelectric laminates are different, then the passband will disappear so that the switching characteristic is achieved. When the same magnetic fields are applied to the laminates, the passband bandwidth of the two-stage cascaded magnetoelectric filter with two magnetoelectric laminates becomes nearly doubled in comparison with the passband filter which contains only one magnetoelectric laminate. The bandpass effect is also improved obviously. This research will provide a theoretical basis for the design, preparation, and application of a new high performance magnetoelectric tunable microwave device. Project supported by the National Natural Science Foundation of China (Grant Nos. 11172285 and 11472259) and the Natural Science Foundation of Zhejiang Province, China (Grant No. LR13A020002).

  8. Cascade model for particle concentration and enstrophy in fully developed turbulence with mass-loading feedback.

    PubMed

    Hogan, R C; Cuzzi, J N

    2007-05-01

    A cascade model is described based on multiplier distributions determined from three-dimensional (3D) direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using psuedospectral methods on up to 512(3) computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34-170 were used to directly determine multiplier distributions on spatial scales three times the Kolmogorov length scale. The multiplier probability distribution functions (PDFs) are well characterized by the beta distribution function. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint probability distribution functions of concentration and enstrophy generated using the cascade model are shown to be in excellent agreement with those derived directly from our 3D simulations. Probabilities predicted by the cascade model are presented at Reynolds numbers well beyond what is achievable by direct simulation. These results clearly indicate that particle mass loading significantly reduces the probabilities of high particle concentration and enstrophy relative to those resulting from unloaded runs. Particle mass density appears to reach a limit at around 100 times the gas density. This approach has promise for significant computational savings in certain applications.

  9. Overall picture of the cascade gamma decay of neutron resonances within a modified practical model

    NASA Astrophysics Data System (ADS)

    Sukhovoj, A. M.; Mitsyna, L. V.; Jovancevic, N.

    2016-05-01

    The intensities of two-step cascades in 43 nuclei of mass number in the range of 28 ≤ A ≤ 200 were approximated to a high degree of precision within a modified version of the practical cascade-gammadecay model introduced earlier. In this version, the rate of the decrease in the model-dependent density of vibrational levels has the same value for any Cooper pair undergoing breakdown. The most probable values of radiative strength functions both for E1 and for M1 transitions are determined by using one or two peaks against a smooth model dependence on the gamma-transition energy. The statement that the thresholds for the breaking of Cooper pairs are higher for spherical than for deformed nuclei is a basic result of the respective analysis. The parameters of the cascade-decay process are now determined to a precision that makes it possible to observe the systematic distinctions between them for nuclei characterized by different parities of neutrons and protons.

  10. Dominance and interloci interactions in transcriptional activation cascades: models explaining compensatory mutations and inheritance patterns.

    PubMed

    Bost, Bruno; Veitia, Reiner A

    2014-01-01

    Mutations in human genes encoding transcription factors are often dominant because one active allele cannot ensure a normal phenotype (haploinsufficiency). In other instances, heterozygous mutations of two genes are required for a phenotype to appear (combined haploinsufficiency). Here, we explore with models (i) the basis of haploinsufficiency and combined haploinsufficiency owing to mutations in transcription activators, and (ii) how the effects of such mutations can be amplified or buffered by subsequent steps in a transcription cascade. We propose that the non-linear (sigmoidal) response of transcription to the concentration of activators can explain haploinsufficiency. We further show that the sigmoidal character of the output of a cascade increases with the number of steps involved, the settings of which will determine the buffering or enhancement of the effects of a decreased concentration of an upstream activator. This exploration provides insights into the bases of compensatory mutations and on interloci interactions underlying oligogenic inheritance patterns.

  11. Testing an Idealized Dynamic Cascade Model of the Development of Serious Violence in Adolescence

    PubMed Central

    Dodge, Kenneth A.; Greenberg, Mark T.; Malone, Patrick S.

    2008-01-01

    A dynamic cascade model of development of serious adolescent violence was proposed and tested through prospective inquiry with 754 children (50% male; 43% African American) from 27 schools at 4 geographic sites followed annually from kindergarten through grade 11 (ages 5 through 18). Self, parent, teacher, peer, observer, and administrative reports provided data. Partial least squares (PLS) analyses revealed a cascade of prediction and mediation: An early social context of disadvantage predicts harsh-inconsistent parenting, which predicts social and cognitive deficits, which predicts conduct problem behavior, which predicts elementary school social and academic failure, which predicts parental withdrawal from supervision and monitoring, which predicts deviant peer associations, which ultimately predicts adolescent violence. Findings suggest targets for in-depth inquiry and preventive intervention. PMID:19037957

  12. Equivalent circuit-level model and improvement of terahertz quantum cascade lasers

    SciTech Connect

    Wei Zhou; Shaobin Liu; Jie Wu; Xiaoliu Zhang; Wu Tang

    2014-04-28

    An equivalent circuit-level model of terahertz (THz) quantum cascade lasers (QCLs) is developed by using rate equations. This model can be employed to investigate the characteristics of THz QCLs accurately and to improve their design. We use the circuit-level model to analyse a new active structure, which can improve the performance of THz QCLs by means of enhancing carrier injection. The simulation result shows that THz QCLs with the new active structure have a much higher performance compared with conventional THz QCLs. The high-performance THz QCLs are expected to be operated at higher temperatures. (lasers)

  13. Monte Carlo modeling of cascade gamma rays in (86)Y PET imaging: preliminary results.

    PubMed

    Zhu, Xuping; El Fakhri, Georges

    2009-07-07

    (86)Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in (90)Y radionuclide therapy. However, (86)Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET (Simulation System for Emission Tomography) to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), single and coincidence statistics and detected photons energy distribution within the PET energy window. A discrepancy of 20% was observed in the absolute scatter fraction, likely caused by differences in the tracking of higher energy cascade gamma photons. On average, the new simulation is 6 times faster than GATE, and the computing time can be further improved by using variance reduction techniques currently available in SimSET. Comparison with phantom acquisitions showed agreements in spatial resolutions and the general shape of projection profiles; however, the standard scatter correction method on the scanner is not directly applicable to (86)Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize (86)Y PET. Compared with conventional (18)F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in (86)Y PET. The two types of contaminations have completely different distribution patterns, which should be considered for the corrections of their effects. Our approach will be further improved in the future in the modeling of random coincidences and tracking of high-energy photons, and simulation results will be used for the development of correction methods in (86)Y PET.

  14. CRT--Cascade Routing Tool to define and visualize flow paths for grid-based watershed models

    USGS Publications Warehouse

    Henson, Wesley R.; Medina, Rose L.; Mayers, C. Justin; Niswonger, Richard G.; Regan, R.S.

    2013-01-01

    The U.S. Geological Survey Cascade Routing Tool (CRT) is a computer application for watershed models that include the coupled Groundwater and Surface-water FLOW model, GSFLOW, and the Precipitation-Runoff Modeling System (PRMS). CRT generates output to define cascading surface and shallow subsurface flow paths for grid-based model domains. CRT requires a land-surface elevation for each hydrologic response unit (HRU) of the model grid; these elevations can be derived from a Digital Elevation Model raster data set of the area containing the model domain. Additionally, a list is required of the HRUs containing streams, swales, lakes, and other cascade termination features along with indices that uniquely define these features. Cascade flow paths are determined from the altitudes of each HRU. Cascade paths can cross any of the four faces of an HRU to a stream or to a lake within or adjacent to an HRU. Cascades can terminate at a stream, lake, or HRU that has been designated as a watershed outflow location.

  15. Effective Reading and Writing Instruction: A Focus on Modeling

    ERIC Educational Resources Information Center

    Regan, Kelley; Berkeley, Sheri

    2012-01-01

    When providing effective reading and writing instruction, teachers need to provide explicit modeling. Modeling is particularly important when teaching students to use cognitive learning strategies. Examples of how teachers can provide specific, explicit, and flexible instructional modeling is presented in the context of two evidence-based…

  16. Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.

    PubMed

    Yang, Hongru; Wu, Lei; Wang, Xiaopeng; Chen, Chao; Yu, Bing; Yang, Bin; Yuan, Liang; Wu, Lipeng; Xue, Zhanli; Li, Gaoping; Wu, Baoning

    2012-12-20

    Streak tube imaging lidar (STIL) is an active imaging system using a pulsed laser transmitter and a streak tube receiver to produce 3D range and intensity imagery. The STIL has recently attracted a great deal of interest and attention due to its advantages of wide azimuth field-of-view, high range and angle resolution, and high frame rate. This work investigates the signal-to-noise performance of STIL systems. A theoretical model for characterizing the signal-to-noise performance of the STIL system with an internal or external intensified streak tube receiver is presented, based on the linear cascaded systems theory of signal and noise propagation. The STIL system is decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Expressions for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. The work presented here is useful for the design and evaluation of STIL systems.

  17. Multiscale equatorial electrojet turbulence: Energy conservation, coupling, and cascades in a baseline 2-D fluid model

    NASA Astrophysics Data System (ADS)

    Hassan, Ehab; Hatch, D. R.; Morrison, P. J.; Horton, W.

    2016-09-01

    Progress in understanding the coupling between plasma instabilities in the equatorial electrojet based on a unified fluid model is reported. Simulations with parameters set to various ionospheric background conditions revealed properties of the gradient-drift and Farley-Buneman instabilities. Notably, sharper density gradients increase linear growth rates at all scales, whereas variations in cross-field E × B drift velocity only affect small-scale instabilities. A formalism defining turbulent fluctuation energy for the system is introduced, and the turbulence is analyzed within this framework. This exercise serves as a useful verification test of the numerical simulations and also elucidates the physics underlying the ionospheric turbulence. Various physical mechanisms involved in the energetics are categorized as sources, sinks, nonlinear transfer, and cross-field coupling. The physics of the nonlinear transfer terms is studied to identify their roles in producing energy cascades, which explain the generation of small-scale structures that are stable in the linear regime. The theory of two-step energy cascading to generate the 3 m plasma irregularities in the equatorial electrojet is verified for the first time in the fluid regime. In addition, the nonlinearity of the system allows the possibility of an inverse energy cascade, potentially responsible for generating large-scale plasma structures at the top of the electrojet as found in different rocket and radar observations.

  18. Displacement cascades in Fesbnd Nisbnd Mnsbnd Cu alloys: RVP model alloys

    NASA Astrophysics Data System (ADS)

    Terentyev, D.; Zinovev, A.; Bonny, G.

    2016-07-01

    Primary damage due to displacement cascades (10-100 keV) has been assessed in Fesbnd 1%Mnsbnd 1%Ni-0.5%Cu and its binary alloys by molecular dynamics (MD), using a recent interatomic potential, specially developed to address features of the Fesbnd Mnsbnd Nisbnd Cu system in the dilute limit. The latter system represents the model matrix for reactor pressure vessel steels. The applied potential reproduces major interaction features of the solutes with point defects in the binary, ternary and quaternary dilute alloys. As compared to pure Fe, the addition of one type of a solute or all solutes together does not change the major characteristics of primary damage. However, the chemical structure of the self-interstitial defects is strongly sensitive to the presence and distribution of Mn and Cu in the matrix. 20 keV cascades were also studied in the Fesbnd Nisbnd Mnsbnd Cu matrix containing <100> dislocation loops (with density of 1024 m-3 and size 2 nm). Two solute distributions were investigated, namely: a random one and one obtained by Metropolis Monte Carlo simulations from our previous work. The presence of the loops did not affect the defect production efficiency but slightly reduced the fraction of isolated self-interstitials and vacancies. The cascade event led to the transformation of the loops into ½<111> glissile configurations with a success rate of 10% in the matrix with random solute distribution, while all the pre-created loops remain stable if the alloy's distribution was applied using the Monte-Carlo method. This suggests that solute segregation to loops "stabilizes" the pre-existing loops against transformation or migration induced by collision cascades.

  19. “Serial” effects in parallel models of reading

    PubMed Central

    Chang, Ya-Ning; Furber, Steve; Welbourne, Stephen

    2012-01-01

    There is now considerable evidence showing that the time to read a word out loud is influenced by an interaction between orthographic length and lexicality. Given that length effects are interpreted by advocates of dual-route models as evidence of serial processing this would seem to pose a serious challenge to models of single word reading which postulate a common parallel processing mechanism for reading both words and nonwords (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001; Rastle, Havelka, Wydell, Coltheart, & Besner, 2009). However, an alternative explanation of these data is that visual processes outside the scope of existing parallel models are responsible for generating the word-length related phenomena (Seidenberg & Plaut, 1998). Here we demonstrate that a parallel model of single word reading can account for the differential word-length effects found in the naming latencies of words and nonwords, provided that it includes a mapping from visual to orthographic representations, and that the nature of those orthographic representations are not preconstrained. The model can also simulate other supposedly “serial” effects. The overall findings were consistent with the view that visual processing contributes substantially to the word-length effects in normal reading and provided evidence to support the single-route theory which assumes words and nonwords are processed in parallel by a common mechanism. PMID:22343366

  20. A cascade interpretation of Lundgren's stretched spiral vortex model for turbulent fine structure

    NASA Astrophysics Data System (ADS)

    Gilbert, Andrew D.

    1993-11-01

    Lundgren's [Phys. Fluids 25, 2193 (1982)] model for turbulent fine structure comprises coherent vortices which wind up vorticity variations into spiral structures; simultaneously the vortices are stretched axially by a background strain field. The model predicts a k-5/3 energy spectrum and is remarkably robust to the form of the coherent vortices and the form of the vorticity variations. To understand this the present article introduces a simple cascade argument which illuminates how the dynamical processes of vortex stretching and reduction of scale conspire to give this Kolmogorov spectrum. Some generalizations are considered.

  1. Mitigating cascades in sandpile models: an immunization strategy for systemic risk?

    NASA Astrophysics Data System (ADS)

    Scala, Antonio; Zlatić, Vinko; Caldarelli, Guido; D'Agostino, Gregorio

    2016-10-01

    We use a simple model of distress propagation (the sandpile model) to show how financial systems are naturally subject to the risk of systemic failures. Taking into account possible network structures among financial institutions, we investigate if simple policies can limit financial distress propagation to avoid system-wide crises, i.e. to dampen systemic risk. We therefore compare different immunization policies (i.e. targeted helps to financial institutions) and find that the information coming from the network topology allows to mitigate systemic cascades by targeting just few institutions.

  2. Examining the Simple View of Reading Model for United States High School Spanish Students

    ERIC Educational Resources Information Center

    Sparks, Richard; Patton, Jon

    2016-01-01

    The Simple View of Reading (SVR) model, which posits that reading comprehension is the product of word decoding and language comprehension that make independent contributions to reading skill, has been found to explain the acquisition of first language (L1) reading and second language (L2) reading in young English language learners (ELLs).…

  3. Hamiltonian-Based Model to Describe the Nonlinear Physics of Cascading Failures in Power-Grid Networks

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Motter, Adilson

    A local disturbance to the state of a power-grid system can trigger a protective response that disables some grid components, which leads to further responses, and may finally result in large-scale failures. In this talk, I will introduce a Hamiltonian-like model of cascading failures in power grids. This model includes the state variables of generators, which are determined by the nonlinear swing equations and power-flow equations, as well as the on/off status of the network components. This framework allows us to view a cascading failure in the power grid as a phase-space transition from a fixed point with high energy to a fixed point with lower energy. Using real power-grid networks, I will demonstrate that possible cascade outcomes can be predicted by analyzing the stability of the system's equilibria. This work adds an important new dimension to the current understanding of cascading failures.

  4. SWIFT: A Dynamical Model of Saccade Generation during Reading

    ERIC Educational Resources Information Center

    Engbert, Ralf; Nuthmann, Antje; Richter, Eike M.; Kliegl, Reinhold

    2005-01-01

    Mathematical models have become an important tool for understanding the control of eye movements during reading. Main goals of the development of the SWIFT model (R. Engbert, A. Longtin, & R. Kliegl, 2002) were to investigate the possibility of spatially distributed processing and to implement a general mechanism for all types of eye movements…

  5. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    PubMed Central

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text reading fluency (efficiency or automaticity)—how its relation to other constructs (e.g., word reading fluency and reading comprehension) changes over time and how it is different from word reading fluency and reading comprehension. We examined (1) developmentally changing relations among word reading fluency, listening comprehension, text reading fluency, and reading comprehension; (2) the relation of reading comprehension to text reading fluency; (3) unique emergent literacy predictors (i.e., phonological awareness, orthographic awareness, morphological awareness, letter name knowledge, vocabulary) of text reading fluency vs. word reading fluency; and (4) unique language and cognitive predictors (e.g., vocabulary, grammatical knowledge, theory of mind) of text reading fluency vs. reading comprehension. These questions were addressed using longitudinal data (two timepoints; Mean age = 5;24 & 6;08) from Korean-speaking children (N = 143). Results showed that listening comprehension was related to text reading fluency at time 2, but not at time 1. At both times text reading fluency was related to reading comprehension, and reading comprehension was related to text reading fluency over and above word reading fluency and listening comprehension. Orthographic awareness was related to text reading fluency over and above other emergent literacy skills and word reading fluency. Vocabulary and grammatical knowledge were independently related to text reading fluency and reading comprehension whereas theory of mind was related to reading comprehension, but not text reading fluency. These results reveal developmental nature of relations and mechanism of text reading fluency in reading development. PMID:26435550

  6. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension.

    PubMed

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text reading fluency (efficiency or automaticity)-how its relation to other constructs (e.g., word reading fluency and reading comprehension) changes over time and how it is different from word reading fluency and reading comprehension. We examined (1) developmentally changing relations among word reading fluency, listening comprehension, text reading fluency, and reading comprehension; (2) the relation of reading comprehension to text reading fluency; (3) unique emergent literacy predictors (i.e., phonological awareness, orthographic awareness, morphological awareness, letter name knowledge, vocabulary) of text reading fluency vs. word reading fluency; and (4) unique language and cognitive predictors (e.g., vocabulary, grammatical knowledge, theory of mind) of text reading fluency vs. reading comprehension. These questions were addressed using longitudinal data (two timepoints; Mean age = 5;24 & 6;08) from Korean-speaking children (N = 143). Results showed that listening comprehension was related to text reading fluency at time 2, but not at time 1. At both times text reading fluency was related to reading comprehension, and reading comprehension was related to text reading fluency over and above word reading fluency and listening comprehension. Orthographic awareness was related to text reading fluency over and above other emergent literacy skills and word reading fluency. Vocabulary and grammatical knowledge were independently related to text reading fluency and reading comprehension whereas theory of mind was related to reading comprehension, but not text reading fluency. These results reveal developmental nature of relations and mechanism of text reading fluency in reading development.

  7. A probabilistic sediment cascade model of sediment transfer in the Illgraben

    NASA Astrophysics Data System (ADS)

    Bennett, G. L.; Molnar, P.; McArdell, B. W.; Burlando, P.

    2014-02-01

    We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000-2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.

  8. Ecological, psychological, and cognitive components of reading difficulties: testing the component model of reading in fourth graders across 38 countries.

    PubMed

    Chiu, Ming Ming; McBride-Chang, Catherine; Lin, Dan

    2012-01-01

    The authors tested the component model of reading (CMR) among 186,725 fourth grade students from 38 countries (45 regions) on five continents by analyzing the 2006 Progress in International Reading Literacy Study data using measures of ecological (country, family, school, teacher), psychological, and cognitive components. More than 91% of the differences in student difficulty occurred at the country (61%) and classroom (30%) levels (ecological), with less than 9% at the student level (cognitive and psychological). All three components were negatively associated with reading difficulties: cognitive (student's early literacy skills), ecological (family characteristics [socioeconomic status, number of books at home, and attitudes about reading], school characteristics [school climate and resources]), and psychological (students' attitudes about reading, reading self-concept, and being a girl). These results extend the CMR by demonstrating the importance of multiple levels of factors for reading deficits across diverse cultures.

  9. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    ERIC Educational Resources Information Center

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text-reading fluency (efficiency or automaticity): how its relation to other constructs (e.g., word-reading fluency, reading comprehension) changes over time and how it is different from word-reading fluency and reading comprehension. The study examined (a) developmentally changing relations…

  10. Cascade fuzzy ART: a new extensible database for model-based object recognition

    NASA Astrophysics Data System (ADS)

    Hung, Hai-Lung; Liao, Hong-Yuan M.; Lin, Shing-Jong; Lin, Wei-Chung; Fan, Kuo-Chin

    1996-02-01

    In this paper, we propose a cascade fuzzy ART (CFART) neural network which can be used as an extensible database in a model-based object recognition system. The proposed CFART networks can accept both binary and continuous inputs. Besides, it preserves the prominent characteristics of a fuzzy ART network and extends the fuzzy ART's capability toward a hierarchical class representation of input patterns. The learning processes of the proposed network are unsupervised and self-organizing, which include coupled top-down searching and bottom-up learning processes. In addition, a global searching tree is built to speed up the learning and recognition processes.

  11. An information propagation model considering incomplete reading behavior in microblog

    NASA Astrophysics Data System (ADS)

    Su, Qiang; Huang, Jiajia; Zhao, Xiande

    2015-02-01

    Microblog is one of the most popular communication channels on the Internet, and has already become the third largest source of news and public opinions in China. Although researchers have studied the information propagation in microblog using the epidemic models, previous studies have not considered the incomplete reading behavior among microblog users. Therefore, the model cannot fit the real situations well. In this paper, we proposed an improved model entitled Microblog-Susceptible-Infected-Removed (Mb-SIR) for information propagation by explicitly considering the user's incomplete reading behavior. We also tested the effectiveness of the model using real data from Sina Microblog. We demonstrate that the new proposed model is more accurate in describing the information propagation in microblog. In addition, we also investigate the effects of the critical model parameters, e.g., reading rate, spreading rate, and removed rate through numerical simulations. The simulation results show that, compared with other parameters, reading rate plays the most influential role in the information propagation performance in microblog.

  12. iCRESTRIGRS: a coupled modeling system for cascading flood-landslide disaster forecasting

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Xue, Xianwu; Hong, Yang; Gourley, Jonathan J.; Lu, Ning; Wan, Zhanming; Hong, Zhen; Wooten, Rick

    2016-12-01

    Severe storm-triggered floods and landslides are two major natural hazards in the US, causing property losses of USD 6 billion and approximately 110-160 fatalities per year nationwide. Moreover, floods and landslides often occur in a cascading manner, posing significant risk and leading to losses that are significantly greater than the sum of the losses from the hazards when acting separately. It is pertinent to couple hydrological and geotechnical modeling processes to an integrated flood-landslide cascading disaster modeling system for improved disaster preparedness and hazard management. In this study, we developed the iCRESTRIGRS model, a coupled flash flood and landslide initiation modeling system, by integrating the Coupled Routing and Excess STorage (CREST) model with the physically based Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) landslide model. The iCRESTRIGRS system is evaluated in four river basins in western North Carolina that experienced a large number of floods, landslides and debris flows triggered by heavy rainfall from Hurricane Ivan during 16-18 September 2004. The modeled hourly hydrographs at four USGS gauge stations show generally good agreement with the observations during the entire storm period. In terms of landslide prediction in this case study, the coupled model has a global accuracy of 98.9 % and a true positive rate of 56.4 %. More importantly, it shows an improved predictive capability for landslides relative to the stand-alone TRIGRS model. This study highlights the important physical connection between rainfall, hydrological processes and slope stability, and provides a useful prototype model system for operational forecasting of flood and landslide.

  13. Cascading uncertainties in flood inundation models to uncertain estimates of damage and loss

    NASA Astrophysics Data System (ADS)

    Fewtrell, Timothy; Michel, Gero; Ntelekos, Alexandros; Bates, Paul

    2010-05-01

    The complexity of flood processes, particularly in urban environments, and the difficulties of collecting data during flood events, presents significant and particular challenges to modellers, especially when considering large geographic areas. As a result, the modelling process incorporates a number of areas of uncertainty during model conceptualisation, construction and evaluation. There is a wealth of literature detailing the relative magnitudes of uncertainties in numerical flood input data (e.g. boundary conditions, model resolution and friction specification) for a wide variety of flood inundation scenarios (e.g. fluvial inundation and surface water flooding). Indeed, recent UK funded projects (e.g. FREE) have explicitly examined the effect of cascading uncertainties in ensembles of GCM output through rainfall-runoff models to hydraulic flood inundation models. However, there has been little work examining the effect of cascading uncertainties in flood hazard ensembles to estimates of damage and loss, the quantity of interest when assessing flood risk. Furthermore, vulnerability is possibly the largest area of uncertainty for (re-)insurers as in-depth and reliable of knowledge of portfolios is difficult to obtain. Insurance industry CAT models attempt to represent a credible range of flood events over large geographic areas and as such examining all sources of uncertainty is not computationally tractable. However, the insurance industry is also marked by a trend towards an increasing need to understand the variability in flood loss estimates derived from these CAT models. In order to assess the relative importance of uncertainties in flood inundation models and depth/damage curves, hypothetical 1-in-100 and 1-in-200 year return period flood events are propagated through the Greenwich embayment in London, UK. Errors resulting from topographic smoothing, friction specification and inflow boundary conditions are cascaded to form an ensemble of flood levels and

  14. Effects of EoS in viscous hydro + cascade model for the RHIC Beam Energy Scan

    NASA Astrophysics Data System (ADS)

    Karpenko, Iu.; Bleicher, M.; Huovinen, P.; Petersen, H.

    2016-12-01

    A state-of-the-art 3+1 dimensional cascade + viscous hydro + cascade model vHLLE+UrQMD has been applied to heavy ion collisions in RHIC Beam Energy Scan range √{sNN} = 7.7 , … , 200 GeV. Based on comparison to available experimental data it was estimated that an effective value of shear viscosity over entropy density ratio η / s in hydrodynamic stage has to decrease from η / s = 0.2 to 0.08 as collision energy increases from √{sNN} = 7.7 to 39 GeV, and to stay at η / s = 0.08 for 39 ≤√{ s} ≤ 200 GeV. In this work we show how an equation of state with first order phase transition affects the hydrodynamic evolution at those collision energies and changes the results of the model as compared to "default scenario" with a crossover type EoS from chiral model.

  15. Reading Strategy Instruction through Mental Modelling

    ERIC Educational Resources Information Center

    Pani, Susmita

    2004-01-01

    Focus in recent times on realistic pedagogy implies that we can no longer depend on a transmission model of training, either for teachers or learners. We need to develop strategies that will help teachers and learners to be co-participators in the learning process. Mental modelling is one technique suggested in this article. It is a technique…

  16. A combined Poisson cluster-cascade stochastic model for temporal precipitation

    NASA Astrophysics Data System (ADS)

    Paschalis, A.; Molnar, P.; Fatichi, S.; Burlando, P.

    2011-12-01

    Stochastic precipitation simulation is a fundamental tool in hydrology to obtain high resolution time series of precipitation for ungauged basins, or sites where data records are short or of coarse temporal resolution. Different stochastic modeling tools have been developed in the last decades in order to simulate precipitation time series that satisfactorily reproduce observed statistical properties. The two most widely used classes of models in hydrology are Poisson cluster processes (e.g. Neyman-Scott, Bartlett-Lewis models) and multiplicative random cascades (MRC). It has been recognized that these two classes of models behave differently across time scales. The Poisson cluster models are generally more suitable for coarser time scales (typically larger than one hour) since they reproduce the clustering nature of precipitation events. However, due to their construction they are unable to capture small scale within storm variability. On the other hand, MRCs have been widely used as disaggregation tools due to their ability to capture small scale features of precipitation through the self-similar cascading structure across scales which phenomenologically resembles the energy cascade in turbulence. For precipitation this self-similar behavior breaks at coarser temporal scales (typically larger than one day), which is a limitation for MRC models. A combined Poisson cluster-cascade stochastic model is presented to simulate point precipitation across a wide range of temporal scales, from annual down to few minutes. The model attempts to exploit the strengths of both modeling methods. It consists of a Poisson cluster model as external process for coarser temporal scales which is coupled with a MRC model used as a downscaling procedure to capture variability at high temporal resolutions of hydrological interest (i.e. on the order of minutes). First we investigate the performance of the two classes of models across scales in terms of marginal intensity distributions

  17. Teaching Science through Pictorial Models during Read-Alouds

    ERIC Educational Resources Information Center

    Oliveira, Alandeom W.; Rivera, Seema; Glass, Rory; Mastroianni, Michael; Wizner, Francine; Amodeo, Vincent

    2013-01-01

    This study examines how three elementary teachers refer to pictorial models (photographs, drawings, and cartoons) during science read-alouds. While one teacher used realistic photographs for the purpose of visually verifying facts about crystals, another employed analytical diagrams as heuristic tools to help students visualize complex target…

  18. A Novel Study: A Situation Model Analysis of Reading Times

    ERIC Educational Resources Information Center

    McNerney, M. Windy; Goodwin, Kerri A.; Radvansky, Gabriel A.

    2011-01-01

    One of the basic findings on situation models and language comprehension is that reading times are affected by the changing event structure in a text. However, many studies have traditionally used multiple, relatively short texts, in which there is little event consistency across the texts. It is unclear to what extent such changes will be…

  19. The Construction of Visual-spatial Situation Models in Children's Reading and Their Relation to Reading Comprehension

    PubMed Central

    Barnes, Marcia A.; Raghubar, Kimberly P.; Faulkner, Heather; Denton, Carolyn A.

    2014-01-01

    Readers construct mental models of situations described by text to comprehend what they read, updating these situation models based on explicitly described and inferred information about causal, temporal, and spatial relations. Fluent adult readers update their situation models while reading narrative text based in part on spatial location information that is consistent with the perspective of the protagonist. The current study investigates whether children update spatial situation models in a similar way, whether there are age-related changes in children's formation of spatial situation models during reading, and whether measures of the ability to construct and update spatial situation models are predictive of reading comprehension. Typically-developing children from ages 9 through 16 years (n=81) were familiarized with a physical model of a marketplace. Then the model was covered, and children read stories that described the movement of a protagonist through the marketplace and were administered items requiring memory for both explicitly stated and inferred information about the character's movements. Accuracy of responses and response times were evaluated. Results indicated that: (a) location and object information during reading appeared to be activated and updated not simply from explicit text-based information but from a mental model of the real world situation described by the text; (b) this pattern showed no age-related differences; and (c) the ability to update the situation model of the text based on inferred information, but not explicitly stated information, was uniquely predictive of reading comprehension after accounting for word decoding. PMID:24315376

  20. The construction of visual-spatial situation models in children's reading and their relation to reading comprehension.

    PubMed

    Barnes, Marcia A; Raghubar, Kimberly P; Faulkner, Heather; Denton, Carolyn A

    2014-03-01

    Readers construct mental models of situations described by text to comprehend what they read, updating these situation models based on explicitly described and inferred information about causal, temporal, and spatial relations. Fluent adult readers update their situation models while reading narrative text based in part on spatial location information that is consistent with the perspective of the protagonist. The current study investigated whether children update spatial situation models in a similar way, whether there are age-related changes in children's formation of spatial situation models during reading, and whether measures of the ability to construct and update spatial situation models are predictive of reading comprehension. Typically developing children from 9 to 16 years of age (N=81) were familiarized with a physical model of a marketplace. Then the model was covered, and children read stories that described the movement of a protagonist through the marketplace and were administered items requiring memory for both explicitly stated and inferred information about the character's movements. Accuracy of responses and response times were evaluated. Results indicated that (a) location and object information during reading appeared to be activated and updated not simply from explicit text-based information but from a mental model of the real-world situation described by the text; (b) this pattern showed no age-related differences; and (c) the ability to update the situation model of the text based on inferred information, but not explicitly stated information, was uniquely predictive of reading comprehension after accounting for word decoding.

  1. Modelling on dynamics properties of a stationary argon cascaded arc plasma flows

    SciTech Connect

    Wei, G. D.; Qi, X.; Yang, L.

    2014-03-15

    The gas dynamics properties of a stationary arc plasma flows are studied through the numerical simulations. A two dimensional axis-symmetric turbulent magneto-hydrodynamic plasma model is developed with the commercial code ANSYS FLUENT. The reliable κ-ε model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier–Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 10{sup 6} A/m{sup 2}. The pressure inside the arc varies from 10{sup 5} Pa to 100 Pa. The temperature at the arc axis can reach as high as 13 600 K. The electric potential drops uniformly along the axis with a magnitude of 160 V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

  2. Niagara Falls Cascade Model for Interstellar Energetic Ions in the Heliosheath

    NASA Astrophysics Data System (ADS)

    Cooper, John F.

    The origin of anomalous cosmic ray ions has long been assumed to be heliospheric pickup ion production from interstellar neutrals and acceleration at the solar wind termination shock. The Voyager-1 shock crossing showed a well-defined boundary for sharply increased keV ion fluxes in the heliosheath but no sign of local acceleration. Ion flux spectra at keV to MeV energies are instead unfolding with outward passage to approximate the E(-1.5) power-law expected for compressional magnetic tubulence. This spectrum provides excellent connection over many energy decades of a maxwellian distribution for local interstellar plasma ions to well-known flux spectra of high energy galactic ions at GeV energies. The Niagara Falls cascade model is proposed that the heliosheath is a transitional region for direct entry of ions from the local interstellar ‘river’ through a permeable heliopause into the supersonic outer heliosphere. As Voyager-1 moves outwards in the heliosheath to the heliopause, energy-dependent transport features can appear in the transitional 0.01 - 1 GeV/n energy band but otherwise a general unfolding to the interstellar limiting spectrum should continue by this model. Spectral regions then become dominated by bulk plasma flow at low energy, cascade transport at intermediate energies, and interstellar shock acceleration at higher energies.

  3. Sediment cascade modelling for stochastic torrential sediment transfers forecasting in a changing alpine climate

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Bardou, Eric; Jaboyedoff, Michel

    2015-04-01

    Alpine ephemeral streams act as links between high altitude erosional processes, slope movements and valley-floor fluvial systems or fan storage. Anticipating future mass wasting from these systems is crucial for hazard mitigation measures. Torrential activity is highly stochastic, with punctual transfers separating long periods of calm, during which the system evolves internally and recharges. Changes can originate from diffuse (rock faces, sheet erosion of bared moraines), concentrated external sources (rock glacier front, slope instabilities) or internal transfers (bed incision or aggradation). The proposed sediment cascade model takes into account those different processes and calculates sediment transfer from the slope to the channel reaches, and then propagates sediments downstream. The two controlling parameters are precipitation series (generated from existing rain gauge data using Gumbel and Extreme Probability Distribution functions) and temperature (generated from local meteorological stations data and IPCC scenarios). Snow accumulation and melting, and thus runoff can then be determined for each subsystem, to account for different altitudes and expositions. External stocks and sediment sources have each a specific response to temperature and precipitation. For instance, production from rock faces is dependent on frost-thaw cycles, in addition to precipitations. On the other hand, landslide velocity, and thus sediment production is linked to precipitations over longer periods of time. Finally, rock glaciers react to long-term temperature trends, but are also prone to sudden release of material during extreme rain events. All those modules feed the main sediment cascade model, constructed around homogeneous torrent reaches, to and from which sediments are transported by debris flows and bedload transport events. These events are determined using a runoff/erosion curve, with a threshold determining the occurrence of debris flows in the system. If a debris

  4. A test of the multiple connections model of reading acquisition.

    PubMed

    Berninger, V W; Chen, A C; Abbott, R D

    1988-10-01

    Within the framework of Society of Mind Theory (Minsky, 1986), learning to read is conceptualized as a process of creating new communication links or neural connections between an existing visual society and an existing linguistic society. Four visual-linguistic connections may become functional: letter-phonemic code, whole word-semantic code, whole word-name code, letter sequence-aural syllabic code. The hypothesis was tested that more than one of these visual-linguistic connections must be taken into account in predicting reading achievement. Results showed that the combination of the composite letter-phoneme variable and the composite whole word-semantic code variable accounted for significantly more variance in oral reading than did either single variable at the end of the first grade. Groups with large absolute discrepancy (1 or more standard scores) or small absolute discrepancy (1/3 standard score or less) on corresponding visual and linguistic skills differed significantly in both oral (whole word-semantic code composite) and silent reading (whole word-semantic code and letter sequence-aural syllabic code composites). There was a relationship between the number of large discrepancies and reading achievement. Results are discussed in reference to neuropsychological models of connectionism (Rumelhart & McClelland, 1986) and working brain systems (Luria, 1973).

  5. Simple models for reading neuronal population codes.

    PubMed Central

    Seung, H S; Sompolinsky, H

    1993-01-01

    In many neural systems, sensory information is distributed throughout a population of neurons. We study simple neural network models for extracting this information. The inputs to the networks are the stochastic responses of a population of sensory neurons tuned to directional stimuli. The performance of each network model in psychophysical tasks is compared with that of the optimal maximum likelihood procedure. As a model of direction estimation in two dimensions, we consider a linear network that computes a population vector. Its performance depends on the width of the population tuning curves and is maximal for width, which increases with the level of background activity. Although for narrowly tuned neurons the performance of the population vector is significantly inferior to that of maximum likelihood estimation, the difference between the two is small when the tuning is broad. For direction discrimination, we consider two models: a perceptron with fully adaptive weights and a network made by adding an adaptive second layer to the population vector network. We calculate the error rates of these networks after exhaustive training to a particular direction. By testing on the full range of possible directions, the extent of transfer of training to novel stimuli can be calculated. It is found that for threshold linear networks the transfer of perceptual learning is nonmonotonic. Although performance deteriorates away from the training stimulus, it peaks again at an intermediate angle. This nonmonotonicity provides an important psychophysical test of these models. PMID:8248166

  6. Influence of Reading Attitude on Reading Achievement: A Test of the Temporal-Interaction Model

    ERIC Educational Resources Information Center

    Martinez, Rebecca S.; Aricak, O. Tolga; Jewell, Jeremy

    2008-01-01

    Despite widespread efforts to prevent reading problems and an abundance of research about best practices in remediating reading skills deficits, reading continues to be exceptionally difficult for many students. Researchers have become interested in investigating the degree to which affective factors such as reading attitude relates to reading…

  7. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE PAGES

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  8. Fitting the Mixed Rasch Model to a Reading Comprehension Test: Exploring Individual Difference Profiles in L2 Reading

    ERIC Educational Resources Information Center

    Aryadoust, Vahid; Zhang, Limei

    2016-01-01

    The present study used the mixed Rasch model (MRM) to identify subgroups of readers within a sample of students taking an EFL reading comprehension test. Six hundred and two (602) Chinese college students took a reading test and a lexico-grammatical knowledge test and completed a Metacognitive and Cognitive Strategy Use Questionnaire (MCSUQ)…

  9. K + production in a cascade model for high-energy nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Cugnon, J.; Lombard, R. M.

    1984-07-01

    The K + production is studied for the p + NaF, Ne + NaF, Ne + Pb systems at 2.1 GeV/ A in the frame of a 3-dimensional cascade model. Owing to the small elementary production cross sections, the K + production is calculated perturbatively. Two kinds of production processes are introduced: baryon-baryon collisions leading to three-particle final states, and pion-nucleon collisions leading to two-body final states. The time evolution of the two processes is studied. The integrated K + cross sections are in good agreement with the experimental data. The contribution of the πN induced mechanism is of the order of 25% for Ne + NaF, but increases with the size of the system. Scaling properties are discussed. A simple rescattering model is used to calculate the invariant cross section for the Ne + NaF case. Good agreement with experiment is obtained, except at forward angles.

  10. Optical feedback effects on terahertz quantum cascade lasers: modelling and applications

    NASA Astrophysics Data System (ADS)

    Rakić, Aleksandar D.; Lim, Yah Leng; Taimre, Thomas; Agnew, Gary; Qi, Xiaoqiong; Bertling, Karl; Han, She; Wilson, Stephen J.; Kundu, Iman; Grier, Andrew; Ikonić, Zoran; Valavanis, Alexander; Demić, Aleksandar; Keeley, James; Li, Lianhe H.; Linfield, Edmund H.; Davies, A. Giles; Harrison, Paul; Ferguson, Blake; Walker, Graeme; Prow, Tarl; Indjin, Dragan; Soyer, H. Peter

    2016-11-01

    Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1-5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model.

  11. Improving the description of proton-induced one-nucleon removal in intranuclear-cascade models

    NASA Astrophysics Data System (ADS)

    Mancusi, Davide; Boudard, Alain; Carbonell, Jaume; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie

    2015-03-01

    It is a well-established fact that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons for this deficiency. We find that a refined description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables, and that neither ingredient is sufficient if taken separately. As a by-product, the predictions for removal of several nucleons are also improved by the refined treatment.

  12. Scaffolding in L2 Reading: How Repetition and an Auditory Model Help Readers

    ERIC Educational Resources Information Center

    Taguchi, Etsuo; Gorsuch, Greta; Lems, Kristin; Rosszell, Rory

    2016-01-01

    Reading fluency research and practice have recently undergone some changes. While past studies and interventions focused on reading speed as their main goal, now more emphasis is being placed on exploring the role prosody plays in reading, and how listening to an audio model of a text while reading may act as a form of scaffolding, or aid, to…

  13. Time domain modeling of terahertz quantum cascade lasers for frequency comb generation.

    PubMed

    Tzenov, Petar; Burghoff, David; Hu, Qing; Jirauschek, Christian

    2016-10-03

    The generation of frequency combs in the mid-infrared and terahertz regimes from compact and potentially cheap sources could have a strong impact on spectroscopy, as many molecules have their rotovibrational bands in this spectral range. Thus, quantum cascade lasers (QCLs) are the perfect candidates for comb generation in these portions of the electromagnetic spectrum. Here we present a theoretical model based on a full numerical solution of Maxwell-Bloch equations suitable for the simulation of such devices. We show that our approach captures the intricate interplay between four wave mixing, spatial hole burning, coherent tunneling and chromatic dispersion which are present in free running QCLs. We investigate the premises for the generation of QCL based terahertz combs. The simulated comb spectrum is in good agreement with experiment, and also the observed temporal pulse switching between high and low frequency components is reproduced. Furthermore, non-comb operation resulting in a complex multimode dynamics is investigated.

  14. Modeling of momentum transport of axially parallel turbulent flows in rod cascades

    NASA Astrophysics Data System (ADS)

    Neelen, Neele

    Problems and boundary conditions of the turbulent flow in heat exchangers, especially for nuclear fuel elements, are treated using mathematical models. Rod cascade flow and the physical fundamentals of turbulent flows are introduced. It is shown that the momentum transport phenomena can be separated into the radial and azimuthal directions. The geometrical characteristics of rod bundle geometries and a regression analysis are considered. The correlation coefficients for the wall parallel vortex viscosity are determined using a numerical optimization method. The order of magnitude of the secondary flow occurring perpendicularly to the main flow direction are determined to be 1 pct to 2 pct of the average axial velocity. The results obtained with the code VELASCO-BS are superior to those of previous codes. The azimuthal vortex viscosity is the decisive parameter, and secondary flow is not important for wall parallel momentum transport.

  15. Developmental cascade model for adolescent substance use from infancy to late adolescence.

    PubMed

    Eiden, Rina D; Lessard, Jared; Colder, Craig R; Livingston, Jennifer; Casey, Meghan; Leonard, Kenneth E

    2016-10-01

    A developmental cascade model for adolescent substance use beginning in infancy was examined in a sample of children with alcoholic and nonalcoholic parents. The model examined the role of parents' alcohol diagnoses, depression and antisocial behavior in a cascading process of risk via 3 major hypothesized pathways: first, via parental warmth/sensitivity from toddler to kindergarten age predicting higher parental monitoring in middle childhood through early adolescence, serving as a protective pathway for adolescent substance use; second, via child low self-regulation in the preschool years to a continuing externalizing behavior problem pathway leading to underage drinking and higher engagement with substance using peers; and third, via higher social competence from kindergarten age through middle childhood being protective against engagement with delinquent and substance using peers, and leading to lower adolescent substance use. The sample consisted of 227 intact families recruited from the community at 12 months of child age. Results were supportive for the first 2 pathways to substance use in late adolescence. Among proximal, early adolescent risks, engagement with delinquent peers and parent's acceptance of underage drinking were significant predictors of late adolescent alcohol and marijuana use. The results highlight the important protective roles of maternal warmth/sensitivity in early childhood to kindergarten age, parental monitoring in middle childhood, and of child self-regulation in the preschool period as reducing risk for externalizing behavior problems, underage drinking, and engagement with delinquent peers in early adolescence. Specific implications for the creation of developmentally fine-tuned preventive intervention are discussed. (PsycINFO Database Record

  16. Modified energy cascade model adapted for a multicrop Lunar greenhouse prototype

    NASA Astrophysics Data System (ADS)

    Boscheri, G.; Kacira, M.; Patterson, L.; Giacomelli, G.; Sadler, P.; Furfaro, R.; Lobascio, C.; Lamantea, M.; Grizzaffi, L.

    2012-10-01

    Models are required to accurately predict mass and energy balances in a bioregenerative life support system. A modified energy cascade model was used to predict outputs of a multi-crop (tomatoes, potatoes, lettuce and strawberries) Lunar greenhouse prototype. The model performance was evaluated against measured data obtained from several system closure experiments. The model predictions corresponded well to those obtained from experimental measurements for the overall system closure test period (five months), especially for biomass produced (0.7% underestimated), water consumption (0.3% overestimated) and condensate production (0.5% overestimated). However, the model was less accurate when the results were compared with data obtained from a shorter experimental time period, with 31%, 48% and 51% error for biomass uptake, water consumption, and condensate production, respectively, which were obtained under more complex crop production patterns (e.g. tall tomato plants covering part of the lettuce production zones). These results, together with a model sensitivity analysis highlighted the necessity of periodic characterization of the environmental parameters (e.g. light levels, air leakage) in the Lunar greenhouse.

  17. Developmental models of learning to read Chinese words.

    PubMed

    Tong, Xiuli; McBride-Chang, Catherine

    2010-11-01

    What is the nature of learning to read Chinese across grade levels? This study tested 199 kindergartners, 172 second graders, and 165 fifth graders on 12 different tasks purportedly tapping constructs representing phonological awareness, morphological awareness, orthographic processing, and subcharacter processing. Confirmatory factor analyses comparing alternative models of these 4 constituents of Chinese word reading revealed different patterns of metalinguistic underpinnings of children's word recognition across grade levels: The best-fitting model for kindergartners represented a print-nonprint dichotomy of constructs. In contrast, 2nd graders showed a fine-grained sensitivity to all 4 hypothesized constructs. Finally, the best-fitting model for 5th graders consisted of a phonological sensitivity construct and a broad lexical morphological-orthographic processing construct. Findings suggest that Hong Kong Chinese children progress from a basic understanding of print versus nonprint to a diversified sensitivity to varied word-reading skills, to a focus on meaning-based word recognition, to the relative exclusion of phonological sensitivity in more advanced readers.

  18. Expanding the Four Resources Model: Reading Visual and Multi-Modal Texts

    ERIC Educational Resources Information Center

    Serafini, Frank

    2012-01-01

    Freebody and Luke proffered an expanded conceptualization of the resources readers utilize when reading and the roles readers adopt during the act of reading. The four resources model, and its associated four roles of the reader, expanded the definition of reading from a simple model of decoding printed texts to a model of constructing meaning and…

  19. Psycholinguistic Theory of Learning to Read Compared to the Traditional Theory Model.

    ERIC Educational Resources Information Center

    Murphy, Robert F.

    A comparison of two models of the reading process--the psycholinguistic model, in which learning to read is seen as a top-down, holistic procedure, and the traditional theory model, in which learning to read is seen as a bottom-up, atomistic procedure--is provided in this paper. The first part of the paper provides brief overviews of the following…

  20. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Osetsky, Y. N.; Stoller, R. E.

    2015-10-01

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (∼0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential. The Gao-Weber potential appears to give a more realistic description of cascade dynamics in SiC, but still has some shortcomings when the defect migration barriers are compared to the ab initio results.

  1. Reverse cascade screening of newborns for hereditary haemochromatosis: a model for other late onset diseases?

    PubMed Central

    Cadet, E; Capron, D; Gallet, M; Omanga-Leke, M; Boutignon, H; Julier, C; Robson, K; Rochette, J

    2005-01-01

    Background: Genetic testing can determine those at risk for hereditary haemochromatosis (HH) caused by HFE mutations before the onset of symptoms. However, there is no optimum screening strategy, mainly owing to the variable penetrance in those who are homozygous for the HFE Cys282Tyr (C282Y) mutation. The objective of this study was to identify the majority of individuals at serious risk of developing HFE haemochromatosis before they developed life threatening complications. Methods: We first estimated the therapeutic penetrance of the C282Y mutation in people living in la Somme, France, using genetic, demographic, biochemical, and follow up data. We examined the benefits of neonatal screening on the basis of increased risk to relatives of newborns carrying one or two copies of the C282Y mutation. Between 1999 and 2002, we screened 7038 newborns from two maternity hospitals in the north of France for the C282Y and His63Asp (H63D) mutations in the HFE gene, using bloodspots collected on Guthrie cards. Family studies and genetic counselling were undertaken, based on the results of the baby's genotype. Findings: In la Somme, we found that 24% of the adults homozygous for the C282Y mutation required at least 5 g iron to be removed to restore normal iron parameters (that is, the therapeutic penetrance). In the reverse cascade screening study, we identified 19 C282Y homozygotes (1/370), 491 heterozygotes (1/14) and 166 compound heterozygotes (1/42) in 7038 newborns tested. The reverse cascade screening strategy resulted in 80 adults being screened for both mutations. We identified 10 previously unknown C282Y homozygotes of whom six (four men and two women) required venesection. Acceptance of neonatal screening was high; parents understood the risks of having HH and the benefits of early detection, but a number of parents were reluctant to take the test themselves. Neonatal screening for HH is straightforward. Reverse cascade screening increased the efficiency of

  2. Hyperpolarization-Activated Current Induces Period-Doubling Cascades and Chaos in a Cold Thermoreceptor Model.

    PubMed

    Xu, Kesheng; Maidana, Jean P; Caviedes, Mauricio; Quero, Daniel; Aguirre, Pablo; Orio, Patricio

    2017-01-01

    In this article, we describe and analyze the chaotic behavior of a conductance-based neuronal bursting model. This is a model with a reduced number of variables, yet it retains biophysical plausibility. Inspired by the activity of cold thermoreceptors, the model contains a persistent Sodium current, a Calcium-activated Potassium current and a hyperpolarization-activated current (Ih) that drive a slow subthreshold oscillation. Driven by this oscillation, a fast subsystem (fast Sodium and Potassium currents) fires action potentials in a periodic fashion. Depending on the parameters, this model can generate a variety of firing patterns that includes bursting, regular tonic and polymodal firing. Here we show that the transitions between different firing patterns are often accompanied by a range of chaotic firing, as suggested by an irregular, non-periodic firing pattern. To confirm this, we measure the maximum Lyapunov exponent of the voltage trajectories, and the Lyapunov exponent and Lempel-Ziv's complexity of the ISI time series. The four-variable slow system (without spiking) also generates chaotic behavior, and bifurcation analysis shows that this is often originated by period doubling cascades. Either with or without spikes, chaos is no longer generated when the Ih is removed from the system. As the model is biologically plausible with biophysically meaningful parameters, we propose it as a useful tool to understand chaotic dynamics in neurons.

  3. Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

    SciTech Connect

    Wampler, William R. Myers, Samuel M.

    2015-01-28

    A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers, and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.

  4. Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Wampler, William R.; Myers, Samuel M.

    2015-01-01

    A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers, and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.

  5. A two-stage cascade model of BOLD responses in human visual cortex.

    PubMed

    Kay, Kendrick N; Winawer, Jonathan; Rokem, Ariel; Mezer, Aviv; Wandell, Brian A

    2013-01-01

    Visual neuroscientists have discovered fundamental properties of neural representation through careful analysis of responses to controlled stimuli. Typically, different properties are studied and modeled separately. To integrate our knowledge, it is necessary to build general models that begin with an input image and predict responses to a wide range of stimuli. In this study, we develop a model that accepts an arbitrary band-pass grayscale image as input and predicts blood oxygenation level dependent (BOLD) responses in early visual cortex as output. The model has a cascade architecture, consisting of two stages of linear and nonlinear operations. The first stage involves well-established computations-local oriented filters and divisive normalization-whereas the second stage involves novel computations-compressive spatial summation (a form of normalization) and a variance-like nonlinearity that generates selectivity for second-order contrast. The parameters of the model, which are estimated from BOLD data, vary systematically across visual field maps: compared to primary visual cortex, extrastriate maps generally have larger receptive field size, stronger levels of normalization, and increased selectivity for second-order contrast. Our results provide insight into how stimuli are encoded and transformed in successive stages of visual processing.

  6. Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

    SciTech Connect

    Wampler, William R.; Myers, Samuel M.

    2014-02-01

    A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defects within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.

  7. Hyperpolarization-Activated Current Induces Period-Doubling Cascades and Chaos in a Cold Thermoreceptor Model

    PubMed Central

    Xu, Kesheng; Maidana, Jean P.; Caviedes, Mauricio; Quero, Daniel; Aguirre, Pablo; Orio, Patricio

    2017-01-01

    In this article, we describe and analyze the chaotic behavior of a conductance-based neuronal bursting model. This is a model with a reduced number of variables, yet it retains biophysical plausibility. Inspired by the activity of cold thermoreceptors, the model contains a persistent Sodium current, a Calcium-activated Potassium current and a hyperpolarization-activated current (Ih) that drive a slow subthreshold oscillation. Driven by this oscillation, a fast subsystem (fast Sodium and Potassium currents) fires action potentials in a periodic fashion. Depending on the parameters, this model can generate a variety of firing patterns that includes bursting, regular tonic and polymodal firing. Here we show that the transitions between different firing patterns are often accompanied by a range of chaotic firing, as suggested by an irregular, non-periodic firing pattern. To confirm this, we measure the maximum Lyapunov exponent of the voltage trajectories, and the Lyapunov exponent and Lempel-Ziv's complexity of the ISI time series. The four-variable slow system (without spiking) also generates chaotic behavior, and bifurcation analysis shows that this is often originated by period doubling cascades. Either with or without spikes, chaos is no longer generated when the Ih is removed from the system. As the model is biologically plausible with biophysically meaningful parameters, we propose it as a useful tool to understand chaotic dynamics in neurons. PMID:28344550

  8. Modeling Reading Development: Cumulative, Incremental Learning in a Computational Model of Word Naming

    ERIC Educational Resources Information Center

    Monaghan, Padraic; Ellis, Andrew W.

    2010-01-01

    Natural reading development gradually builds up to the adult vocabulary over a period of years. This has an effect on lexical processing: early-acquired words are processed more quickly and more accurately than later-acquired words. We present a connectionist model of reading, learning to map orthography onto phonology to simulate this natural…

  9. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    SciTech Connect

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  10. Potential Cascading Failures of Long-term Shoreline Stabilization in a Coupled Morphoeconomic Coastline Evolution Model

    NASA Astrophysics Data System (ADS)

    Ells, K. D.; McNamara, D.; Murray, A.

    2013-12-01

    Systems with many interconnected parts can be susceptible to a cascade of failures, where the failure of one or more constituents can trigger the failure of others. This phenomenon has received significant attention in various applications of complex networks, but for many environmental systems the component parts and extent of their connectivity are not readily evident. Recent modeling work has shown that the evolution of many large-scale coastline shapes can be understood by the directional distribution of waves reaching the coast from offshore (i.e. wave climate), and that coastal communities responding to erosion with long-term shoreline stabilization (e.g. beach nourishment or seawalls) may perturb patterns of shoreline change far from their own locality. Economic strategies for shoreline stabilization - historically a spatially decentralized practice - are subject to constraints ranging from the scarcity of nourishment sand to coastal property values and locally observed erosion rates. Initial investigations into the coupling between large-scale coastline morphology and coastal economies along a cuspate cape coastline (similar to the Carolina capes, USA) have shown that long-term beach nourishment can become unsustainable due to the depletion of a finite sand reservoir, and that the spatial dynamics of abandonment depend on the distribution of both erosion rates and property values. Here we extend this analysis to consider: 1) how the abandonment of beach nourishment in one location may induce increased nourishment rates and potential abandonment in other locations alongshore, and 2) the consequences of hard-structured alternatives to beach nourishment (e.g. seawalls). The potential for cascading effects may be most significant along coastlines with subtle curvature and wave climates dominated by low-angle waves, broadly similar to much of the New Jersey and Delmarva coasts, USA, a region with a complex history of shoreline stabilization.

  11. New capabilities of the Liège intranuclear-cascade model for particle-transport codes

    NASA Astrophysics Data System (ADS)

    Mancusi, D.; Boudard, A.; Cugnon, J.; David, J.-C.; Hagiwara, M.; Leprince, A.; Leray, S.

    2014-06-01

    We review and discuss the latest developments of the Liège Intranuclear Cascade model. The new capabilities are illustrated by comparisons with selected experimental data. We also present examples of thick-target calculations performed using particle-transport codes.

  12. A plate-driven model for enigmatic volcanic history of the Cascades-Yellowstone System

    NASA Astrophysics Data System (ADS)

    Szwaja, S.; Kincaid, C. R.; Druken, K. A.; MacDougall, J.

    2013-12-01

    The Cascades subduction system in the Pacific Northwest (USA) represents a complex tectonic setting, where rollback subduction of the Juan de Fuca plate beneath the North American plate, back-arc extension, and a possible mantle plume have been proposed to explain the complicated volcanic trends observed over the past 20 Ma. Plume and non-plume models have been developed to reconcile the voluminous Columbia River/Steens Flood Basalts (CSFB) (~20 Ma), the age progressive (15 Ma to present) Snake River Plain (SRP) that terminates at Yellowstone and the opposite, or westward trending High Lava Plains (HLP) volcanic track of eastern/central Oregon. We present results from laboratory experiments designed to test a plate-driven model for reproducing gross spatial-temporal characteristics of these three magmatic features. Models use a glucose fluid with temperature dependent viscosity in representing Earth's mantle and continuous rubber belts that kinematically reproduce subduction trends for the Cascades system. Experiments begin at 20 Ma with a volume of mantle residuum in the Cascades wedge that is elongated and restricted in the trench-parallel and trench-normal directions, respectively. The underlying assumption is that residuum was created in the wedge during an earlier plate steepening event that caused the flood basalts. Our models characterize dispersion patterns for the melt residuum material as it deforms within four-dimensional wedge circulation fields driven by rollback subduction (e.g. with a translational component of motion). Results show that residuum viscosity, relative to the ambient fluid, determines whether anomalous fluid can evolve to a morphology that matches the SRP/HLP tracks over ~15-20Ma. A weak residuum (e.g. retained partial melt) deforms over this time scale from the initial north-south oriented feature to an east-west trending morphology that is thin in both depth and north-south extent, material initially beneath CSFB is offset to the

  13. Micro-angiography for neuro-vascular imaging. II. Cascade model analysis.

    PubMed

    Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R; Hoffmann, Kenneth R

    2003-11-01

    A micro-angiographic detector was designed and its performance was previously tested to evaluate its feasibility as an improvement over current x-ray detectors for neuro-interventional imaging. The detector was shown to have a modulation transfer function value of about 2% at the Nyquist frequency of 10 cycles/mm and a zero frequency detective quantum efficiency [DQE(0)] value of about 55%. An assessment of the system was required to evaluate whether the current system was performing at its full potential and to determine if any of its components could be optimized to further improve the output. For the purpose, in this study, the parallel cascade theory was used to analyze the performance of the detector under neuro-angiographic conditions by studying the output at the various stages in the imaging chain. A simple model for the spread of light in the CsI(Tl) entrance phosphor was developed and the resolution degradation due to K-fluorescence absorption was calculated. The total gain of the system was found to result in 21 e(-) (rms) detected at the charge coupled device per absorbed x-ray photon. The gain and the spread of quanta in the imaging chain were used to calculate theoretically the DQE using the parallel cascade model. The results of the model-based calculations matched fairly well with the experimental data previously obtained. This model was then used to optimize the phosphor thickness for the detector. The results showed that the area under the DQE curve had a maximum value at 150 microm of CsI(Tl), though when weighted by the squared signal in frequency space of a 100-microm-diam iodinated vessel, the integral DQE reached a maximum at 250 microm of CsI(Tl). Further, possible locations for gain increase in the imaging chain were determined, and the output of the improved system was simulated. Thus a theoretical analysis for the micro-angiographic detector was performed to better assess its potential.

  14. Can evolution provide perfectly optimal solutions for a universal model of reading?

    PubMed

    Behme, Christina

    2012-10-01

    Frost has given us good reason to question the universality of existing computational models of reading. Yet, he has not provided arguments showing that all languages share fundamental and invariant reading universals. His goal of outlining the blueprint principles for a universal model of reading is premature. Further, it is questionable whether natural evolution can provide the optimal solutions that Frost invokes.

  15. Influence maximization in social networks under an independent cascade-based model

    NASA Astrophysics Data System (ADS)

    Wang, Qiyao; Jin, Yuehui; Lin, Zhen; Cheng, Shiduan; Yang, Tan

    2016-02-01

    The rapid growth of online social networks is important for viral marketing. Influence maximization refers to the process of finding influential users who make the most of information or product adoption. An independent cascade-based model for influence maximization, called IMIC-OC, was proposed to calculate positive influence. We assumed that influential users spread positive opinions. At the beginning, users held positive or negative opinions as their initial opinions. When more users became involved in the discussions, users balanced their own opinions and those of their neighbors. The number of users who did not change positive opinions was used to determine positive influence. Corresponding influential users who had maximum positive influence were then obtained. Experiments were conducted on three real networks, namely, Facebook, HEP-PH and Epinions, to calculate maximum positive influence based on the IMIC-OC model and two other baseline methods. The proposed model resulted in larger positive influence, thus indicating better performance compared with the baseline methods.

  16. Testing a developmental cascade model of adolescent substance use trajectories and young adult adjustment

    PubMed Central

    LYNNE-LANDSMAN, SARAH D.; BRADSHAW, CATHERINE P.; IALONGO, NICHOLAS S.

    2013-01-01

    Developmental models highlight the impact of early risk factors on both the onset and growth of substance use, yet few studies have systematically examined the indirect effects of risk factors across several domains, and at multiple developmental time points, on trajectories of substance use and adult adjustment outcomes (e.g., educational attainment, mental health problems, criminal behavior). The current study used data from a community epidemiologically defined sample of 678 urban, primarily African American youth, followed from first grade through young adulthood (age 21) to test a developmental cascade model of substance use and young adult adjustment outcomes. Drawing upon transactional developmental theories and using growth mixture modeling procedures, we found evidence for a developmental progression from behavioral risk to adjustment problems in the peer context, culminating in a high-risk trajectory of alcohol, cigarette, and marijuana use during adolescence. Substance use trajectory membership was associated with adjustment in adulthood. These findings highlight the developmental significance of early individual and interpersonal risk factors on subsequent risk for substance use and, in turn, young adult adjustment outcomes. PMID:20883591

  17. Development of IDF-curves for tropical india by random cascade modeling

    NASA Astrophysics Data System (ADS)

    Rana, A.; Bengtsson, L.; Olsson, J.; Jothiprakash, V.

    2013-04-01

    Efficient design of urban drainage systems is based on statistical analysis of past rainfall events at fine time scales. However, fine time scale rainfall data are usually lacking in many parts of the world. A possible way forward is to develop methods to derive fine time scale rain intensities from daily observations. This paper applied cascade-based disaggregation modeling for generation of fine time scale rainfall data for Mumbai, India from daily rainfall data. These data were disaggregated to 10-min values. The model was used to disaggregate daily data for the period 1951-2004 and develop intensity-duration-frequency (IDF) relationships. This disaggregation technique is commonly used assuming scale-invariance using constant parameters. For the Mumbai rains it was found better to use parameters dependent on time scale and rain volume. Very good agreement between modeled and observed disaggregation series was found for the time scales larger than 1/2 h for the 1/2-yr period when short term data were available. Although the parameters were allowed to change with time scale, the rain intensities of duration shorter than 1/2 h were overestimated. When IDF-curves had been established, they showed that the current design standard for Mumbai city, 25 mm h-1, has a return period of less than one year. Thus, annual recurring flooding problems in Mumbai appear evident.

  18. Market disruption, cascading effects, and economic recovery:a life-cycle hypothesis model.

    SciTech Connect

    Sprigg, James A.

    2004-11-01

    This paper builds upon previous work [Sprigg and Ehlen, 2004] by introducing a bond market into a model of production and employment. The previous paper described an economy in which households choose whether to enter the labor and product markets based on wages and prices. Firms experiment with prices and employment levels to maximize their profits. We developed agent-based simulations using Aspen, a powerful economic modeling tool developed at Sandia, to demonstrate that multiple-firm economies converge toward the competitive equilibria typified by lower prices and higher output and employment, but also suffer from market noise stemming from consumer churn. In this paper we introduce a bond market as a mechanism for household savings. We simulate an economy of continuous overlapping generations in which each household grows older in the course of the simulation and continually revises its target level of savings according to a life-cycle hypothesis. Households can seek employment, earn income, purchase goods, and contribute to savings until they reach the mandatory retirement age; upon retirement households must draw from savings in order to purchase goods. This paper demonstrates the simultaneous convergence of product, labor, and savings markets to their calculated equilibria, and simulates how a disruption to a productive sector will create cascading effects in all markets. Subsequent work will use similar models to simulate how disruptions, such as terrorist attacks, would interplay with consumer confidence to affect financial markets and the broader economy.

  19. A dynamic cascade model of the development of substance-use onset.

    PubMed

    Dodge, Kenneth A; Malone, Patrick S; Lansford, Jennifer E; Miller, Shari; Pettit, Gregory S; Bates, John E

    2009-01-01

    Although the onset of illicit substance use during adolescence can hit parents abruptly like a raging flood, its origins likely start as a trickle in early childhood. Understanding antecedent factors and how they grow into a stream that leads to adolescent drug use is important for theories of social development as well as policy formulations to prevent onset. Based on a review of the extant literature, we posited a dynamic cascade model of the development of adolescent substance-use onset, specifying that (1) temporally distinct domains of biological factors, social ecology, early parenting, early conduct problems, early peer relations, adolescent parenting, and adolescent peer relations would predict early substance-use onset; (2) each domain would predict the temporally next domain; (3) each domain would mediate the impact of the immediately preceding domain on substance use; and (4) each domain would increment the previous domain in predicting substance use. The model was tested with a longitudinal sample of 585 boys and girls from the Child Development Project, who were followed from prekindergarten through Grade 12. Multiple variables in each of the seven predictor domains were assessed annually through direct observations, testing, peer nominations, school records, and parent-, teacher-, and self-report. Partial least-squares analyses tested hypotheses. Of the sample, 5.2% had engaged in substance use by Grade 7, and 51.3% of the sample had engaged in substance use by Grade 12. Five major empirical findings emerged: (1) Most variables significantly predicted early substance-use onset; (2) predictor variables were significantly related to each other in a web of correlations; (3) variables in each domain were significantly predicted by variables in the temporally prior domain; (4) each domain's variables significantly mediated the impact of the variables in the temporally prior domain on substance-use outcomes; and (5) variables in each domain significantly

  20. Open standards for cascade models for RHIC: Volume 1. Proceedings of RIKEN BNL Research Center workshop

    SciTech Connect

    1997-10-01

    It is widely recognized that cascade models are potentially effective and powerful tools for interpreting and predicting multi-particle observables in heavy ion physics. However, the lack of common standards, documentation, version control, and accessibility have made it difficult to apply objective scientific criteria for evaluating the many physical and algorithmic assumptions or even to reproduce some published results. The first RIKEN Research Center workshop was proposed by Yang Pang to address this problem by establishing open standards for original codes for applications to nuclear collisions at RHIC energies. The aim of this first workshop is: (1) to prepare a WWW depository site for original source codes and detailed documentation with examples; (2) to develop and perform standardized test for the models such as Lorentz invariance, kinetic theory comparisons, and thermodynamic simulations; (3) to publish a compilation of results of the above work in a journal e.g., ``Heavy Ion Physics``; and (4) to establish a policy statement on a set of minimal requirements for inclusion in the OSCAR-WWW depository.

  1. Parallelizing Backpropagation Neural Network Using MapReduce and Cascading Model.

    PubMed

    Liu, Yang; Jing, Weizhe; Xu, Lixiong

    2016-01-01

    Artificial Neural Network (ANN) is a widely used algorithm in pattern recognition, classification, and prediction fields. Among a number of neural networks, backpropagation neural network (BPNN) has become the most famous one due to its remarkable function approximation ability. However, a standard BPNN frequently employs a large number of sum and sigmoid calculations, which may result in low efficiency in dealing with large volume of data. Therefore to parallelize BPNN using distributed computing technologies is an effective way to improve the algorithm performance in terms of efficiency. However, traditional parallelization may lead to accuracy loss. Although several complements have been done, it is still difficult to find out a compromise between efficiency and precision. This paper presents a parallelized BPNN based on MapReduce computing model which supplies advanced features including fault tolerance, data replication, and load balancing. And also to improve the algorithm performance in terms of precision, this paper creates a cascading model based classification approach, which helps to refine the classification results. The experimental results indicate that the presented parallelized BPNN is able to offer high efficiency whilst maintaining excellent precision in enabling large-scale machine learning.

  2. Predator prey oscillations in a simple cascade model of drift wave turbulence

    SciTech Connect

    Berionni, V.; Guercan, Oe. D.

    2011-11-15

    A reduced three shell limit of a simple cascade model of drift wave turbulence, which emphasizes nonlocal interactions with a large scale mode, is considered. It is shown to describe both the well known predator prey dynamics between the drift waves and zonal flows and to reduce to the standard three wave interaction equations. Here, this model is considered as a dynamical system whose characteristics are investigated. The analytical solutions for the purely nonlinear limit are given in terms of the Jacobi elliptic functions. An approximate analytical solution involving Jacobi elliptic functions and exponential growth is computed using scale separation for the case of unstable solutions that are observed when the energy injection rate is high. The fixed points of the system are determined, and the behavior around these fixed points is studied. The system is shown to display periodic solutions corresponding to limit cycle oscillations, apparently chaotic phase space orbits, as well as unstable solutions that grow slowly while oscillating rapidly. The period doubling route to transition to chaos is examined.

  3. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

    NASA Technical Reports Server (NTRS)

    Perry, Bruce A.; Anderson, Molly S.

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

  4. Optimisation of cascaded Yb fiber amplifier chains using numerical-modelling.

    PubMed

    He, F; Price, J H; Vu, K T; Malinowski, A; Sahu, J K; Richardson, D J

    2006-12-25

    We show that it is possible to adapt existing software packages developed originally for modeling telecommunication devices and systems to reliably predict and optimize the performance of high-power Ytterbium-doped fiber amplifier and laser systems. The ready availability of a flexible, user-friendly design tool should be of considerable practical interest to scientists and engineers working with this important new laser technology since Ytterbium amplifier and amplifier cascades are often difficult to optimize experimentally due to the three-level nature of the Ytterbium laser transition. As examples of the utility and accuracy of the software, as well as the complexity of the systems and amplifier properties that can be successfully modeled, we present a comparison of experimental and theoretical results for individual core and cladding pumped amplifiers, and also for an ultra-short pulse four-stage amplifier system optimized both to provide a broad gain bandwidth and to minimize nonlinear effects. We also show how high energy 100 ns pulses with complex user definable temporal profiles can be created in a gain-saturated amplifier by suitable pre-shaping of the low-energy input pulses. Furthermore, with appropriate modifications the same software package can be applied to fiber amplifiers based on other rare-earth elements and glass hosts.

  5. Parallelizing Backpropagation Neural Network Using MapReduce and Cascading Model

    PubMed Central

    Liu, Yang; Jing, Weizhe; Xu, Lixiong

    2016-01-01

    Artificial Neural Network (ANN) is a widely used algorithm in pattern recognition, classification, and prediction fields. Among a number of neural networks, backpropagation neural network (BPNN) has become the most famous one due to its remarkable function approximation ability. However, a standard BPNN frequently employs a large number of sum and sigmoid calculations, which may result in low efficiency in dealing with large volume of data. Therefore to parallelize BPNN using distributed computing technologies is an effective way to improve the algorithm performance in terms of efficiency. However, traditional parallelization may lead to accuracy loss. Although several complements have been done, it is still difficult to find out a compromise between efficiency and precision. This paper presents a parallelized BPNN based on MapReduce computing model which supplies advanced features including fault tolerance, data replication, and load balancing. And also to improve the algorithm performance in terms of precision, this paper creates a cascading model based classification approach, which helps to refine the classification results. The experimental results indicate that the presented parallelized BPNN is able to offer high efficiency whilst maintaining excellent precision in enabling large-scale machine learning. PMID:27217823

  6. Extension of the Liège intranuclear-cascade model to reactions induced by light nuclei

    NASA Astrophysics Data System (ADS)

    Mancusi, Davide; Boudard, Alain; Cugnon, Joseph; David, Jean-Christophe; Kaitaniemi, Pekka; Leray, Sylvie

    2014-11-01

    The purpose of this paper is twofold. First, we present the extension of the Liège intranuclear-cascade model to reactions induced by light ions. We describe here the ideas upon which we built our treatment of nucleus-nucleus reactions and we compare the model predictions against a vast set of heterogeneous experimental data. In spite of the discussed limitations of the intranuclear-cascade scheme, we find that our model yields valid predictions for a number of observables and positions itself as one of the most attractive alternatives available to geant4 users for the simulation of light-ion-induced reactions. Second, we describe the c++ version of the code, which is physicswise equivalent to the legacy version, is available in geant4, and will serve as the basis for all future development of the model.

  7. Brain-Based Reading Model for Students Who Struggle with Reading

    ERIC Educational Resources Information Center

    Cowan, Wanda

    2009-01-01

    Despite educational reforms to increase standards, many American children fail to read at levels that will enable them to compete in higher education and in the global economy. Standardized testing has reported a gradual decline in the reading scores of local second grade elementary students. The purpose of this project study was to create a…

  8. Modeling strategic competition in hydro-thermal electricity generation markets with cascaded reservoir-hydroelectric generation plants

    NASA Astrophysics Data System (ADS)

    Uluca, Basak

    This dissertation aims to achieve two goals. The first is to model the strategic interactions of firms that own cascaded reservoir-hydro plants in oligopolistic and mixed oligopolistic hydrothermal electricity generation markets. Although competition in thermal generation has been extensively modeled since the beginning of deregulation, the literature on competition in hydro generation is still limited; in particular, equilibrium models of oligopoly that study the competitive behavior of firms that own reservoir-hydro plants along the same river in hydrothermal electricity generation markets are still under development. In competitive markets, when the reservoirs are located along the same river, the water released from an upstream reservoir for electricity generation becomes input to the immediate downstream reservoir, which may be owned by a competitor, for current or future use. To capture the strategic interactions among firms with cascaded reservoir-hydro plants, the Upstream-Conjecture approach is proposed. Under the Upstream-Conjecture approach, a firm with an upstream reservoir-hydro plant assumes that firms with downstream reservoir-hydro plants will respond to changes in the upstream firm's water release by adjusting their water release by the same amount. The results of the Upstream Conjecture experiments indicate that firms that own upstream reservoirs in a cascade may have incentive to withhold or limit hydro generation, forcing a reduction in the utilization of the downstream hydro generation plants that are owned by competitors. Introducing competition to hydroelectricity generation markets is challenging and ownership allocation of the previously state-owned cascaded reservoir-hydro plants through privatization can have significant impact on the competitiveness of the generation market. The second goal of the dissertation is to extract empirical guidance about best policy choices for the ownership of the state-owned generation plants, including the

  9. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    SciTech Connect

    Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

    2015-06-03

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.

  10. Teaching Science Through Pictorial Models During Read-Alouds

    NASA Astrophysics Data System (ADS)

    Oliveira, Alandeom W.; Rivera, Seema; Glass, Rory; Mastroianni, Michael; Wizner, Francine; Amodeo, Vincent

    2013-03-01

    This study examines how three elementary teachers refer to pictorial models (photographs, drawings, and cartoons) during science read-alouds. While one teacher used realistic photographs for the purpose of visually verifying facts about crystals, another employed analytical diagrams as heuristic tools to help students visualize complex target systems (rainbow formation and human eye functioning). Another teacher used fictional cartoons to engage students in analogical storytelling, communicating animal camouflage as analogous to human "blending in." However, teachers did not always explicitly convey the representational nature of pictorial models (analog and target as separate entities). It is argued that teachers need to become more aware of how they refer to pictorial models in children's science books and how to promote student visual literacy.

  11. Forty-Five Ways to Teach Reading: A Model for Classifying Reading Approaches. IMRID Papers and Reports, Volume V, No. 5.

    ERIC Educational Resources Information Center

    Woodcock, Richard W.

    This paper presents a model for classifying initial approaches to the teaching of reading. The model consists of three dimensions: the degree of structuring of the program, the sequence of gradation of reading units, and the kind of symbol system used in the initial stages of reading instruction. The degrees of structuring refers to programs such…

  12. Two-temperature model in molecular dynamics simulations of cascades in Ni-based alloys

    DOE PAGES

    Zarkadoula, Eva; Samolyuk, German; Weber, William J.

    2017-01-03

    In high-energy irradiation events, energy from the fast moving ion is transferred to the system via nuclear and electronic energy loss mechanisms. The nuclear energy loss results in the creation of point defects and clusters, while the energy transferred to the electrons results in the creation of high electronic temperatures, which can affect the damage evolution. In this paper, we perform molecular dynamics simulations of 30 keV and 50 keV Ni ion cascades in nickel-based alloys without and with the electronic effects taken into account. We compare the results of classical molecular dynamics (MD) simulations, where the electronic effects aremore » ignored, with results from simulations that include the electronic stopping only, as well as simulations where both the electronic stopping and the electron-phonon coupling are incorporated, as described by the two temperature model (2T-MD). Finally, our results indicate that the 2T-MD leads to a smaller amount of damage, more isolated defects and smaller defect clusters.« less

  13. Evaluation of the Interactionist Model of Socioeconomic Status and Problem Behavior: A Developmental Cascade across Generations

    PubMed Central

    Martin, Monica J.; Conger, Rand D.; Schofield, Thomas J.; Dogan, Shannon J.; Widaman, Keith F.; Donnellan, M. Brent; Neppl, Tricia K.

    2010-01-01

    The current multigenerational study evaluates the utility of the Interactionist Model of Socioeconomic Influence on human development (IMSI) in explaining problem behaviors across generations. The IMSI proposes that the association between socioeconomic status (SES) and human development involves a dynamic interplay that includes both social causation (SES influences human development) and social selection (individual characteristics affect SES). As part of the developmental cascade proposed by the IMSI, the findings from this investigation showed that G1 adolescent problem behavior predicted later G1 SES, family stress, and parental emotional investments, as well as the next generation of children's problem behavior. These results are consistent with a social selection view. Consistent with the social causation perspective, we found a significant relation between G1 SES and family stress, and in turn, family stress predicted G2 problem behavior. Finally, G1 adult SES predicted both material and emotional investments in the G2 child. In turn, emotional investments predicted G2 problem behavior, as did material investments. Some of the predicted pathways varied by G1 parent gender. The results are consistent with the view that processes of both social selection and social causation account for the association between SES and human development. PMID:20576188

  14. Early-late genes of the ecdysone cascade as models for transcriptional studies

    PubMed Central

    Mazina, Marina Yu; Nikolenko, Julia V; Fursova, Nadezda A; Nedil'ko, Petr N; Krasnov, Aleksey N; Vorobyeva, Nadezhda E

    2015-01-01

    The DHR3 and Hr4 early-late genes of the ecdysone cascade are described as models for transcriptional studies in Drosophila cells. In a set of experiments, it became clear that these genes are a convenient and versatile system for research into the physiological conditions upon 20-hydroxyecdysone induction. DHR3 and Hr4 gene transcription is characterized by fast activation kinetics, which enables transcriptional studies without the influence of indirect effects. A limited number of activated genes (only 73 genes are induced one hour after treatment) promote the selectivity of transcriptional studies via 20-hydroxyecdysone induction. DHR3 and Hr4 gene expression is dose dependent, is completely controlled by the hormone titer and decreases within hours of 20-hydroxyecdysone withdrawal. The DHR3 and Hr4 gene promoters become functional within 20 minutes after induction, which makes them useful tools for investigation if the early activation process. Their transcription is controlled by the RNA polymerase II pausing mechanism, which is widespread in the genome of Drosophila melanogaster but is still underinvestigated. Uniform expression activation of the DHR3 and Hr4 genes in a cell population was confirmed at both the RNA and protein levels. Homogeneity of the transcription response makes DHR3/Hr4 system valuable for investigation of the protein dynamics during transcription induction. PMID:26506480

  15. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Integration with Models of Other Water Recovery Subsystems

    NASA Technical Reports Server (NTRS)

    Perry, Bruce; Anderson, Molly

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station (ISS) Water Processor Assembly (WPA) to form a complete Water Recovery System (WRS) for future missions. Independent chemical process simulations with varying levels of detail have previously been developed using Aspen Custom Modeler (ACM) to aid in the analysis of the CDS and several WPA components. The existing CDS simulation could not model behavior during thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. The first part of this paper describes modifications to the ACM model of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version of the model can accurately predict behavior during thermal startup for both NaCl solution and pretreated urine feeds. The model is used to predict how changing operating parameters and design features of the CDS affects its performance, and conclusions from these predictions are discussed. The second part of this paper describes the integration of the modified CDS model and the existing WPA component models into a single WRS model. The integrated model is used to demonstrate the effects that changes to one component can have on the dynamic behavior of the system as a whole.

  16. Modeling Reading Vocabulary Learning in Deaf Children in Bilingual Education Programs

    ERIC Educational Resources Information Center

    Hermans, Daan; Knoors, Harry; Ormel, Ellen; Verhoeven, Ludo

    2008-01-01

    The acquisition of reading vocabulary is one of the major challenges for deaf children in bilingual education programs. Deaf children have to acquire a written lexicon that can effectively be used in reading. In this paper, we present a developmental model that describes reading vocabulary acquisition of deaf children in bilingual education…

  17. Exploring Gains in Reading and Mathematics Achievement among Regular and Exceptional Students Using Growth Curve Modeling

    ERIC Educational Resources Information Center

    Shin, Tacksoo; Davison, Mark L.; Long, Jeffrey D.; Chan, Chi-Keung; Heistad, David

    2013-01-01

    Using four-wave longitudinal reading and mathematics data (4th to 7th grades) from a large urban school district, growth curve modeling was used as a tool for examining three research questions: Are achievement gaps closing in reading and mathematics? What are the associations between prior-achievement and growth across the reading and mathematics…

  18. Ericksen number and Deborah number cascade predictions of a model for liquid crystalline polymers for simple shear flow

    NASA Astrophysics Data System (ADS)

    Klein, D. Harley; Leal, L. Gary; García-Cervera, Carlos J.; Ceniceros, Hector D.

    2007-02-01

    We consider the behavior of the Doi-Marrucci-Greco (DMG) model for nematic liquid crystalline polymers in planar shear flow. We found the DMG model to exhibit dynamics in both qualitative and quantitative agreement with experimental observations reported by Larson and Mead [Liq. Cryst. 15, 151 (1993)] for the Ericksen number and Deborah number cascades. For increasing shear rates within the Ericksen number cascade, the DMG model displays three distinct regimes: stable simple shear, stable roll cells, and irregular structure accompanied by disclination formation. In accordance with experimental observations, the model predicts both ±1 and ±1/2 disclinations. Although ±1 defects form via the ridge-splitting mechanism first identified by Feng, Tao, and Leal [J. Fluid Mech. 449, 179 (2001)], a new mechanism is identified for the formation of ±1/2 defects. Within the Deborah number cascade, with increasing Deborah number, the DMG model exhibits a streamwise banded texture, in the absence of disclinations and roll cells, followed by a monodomain wherein the mean orientation lies within the shear plane throughout the domain.

  19. Improvements in quantum cascade laser performance through comprehensive modeling and experiments

    NASA Astrophysics Data System (ADS)

    Howard, Scott Sheridan

    Prior to the invention of the quantum cascade (QC) laser, many applications based on mid-infrared (mid-IR) laser absorption spectroscopy were not be explored. Development of the QC laser provided an inherently compact, semiconductor based, and tunable mid-IR source that could be used for laser absorption spectroscopy. Additionally, QC lasers can be designed to emit at a specific wavelength within a very wide wavelength range from between 3 and 30 mum and can be fabricated to operate single-mode to clearly scan mid-IR absorption "fingerprints" [1]. This allows lasers to be tailored to the exact wavelength of an absorption feature. Two examples of absorption spectroscopy experiments were carried out as part of this dissertation and described herein: C60 in space and dissolved gasses in living tissue. Although QC lasers allow for application development in the mid-IR, they are inefficient and heat dissipation is problematic. First generation QC lasers relied on either bulky cryogenic cooling systems for continuous wave operation or large, expensive pulse generators [2]. Later, advances in QC laser design, growth, and fabrication led to room-temperature continuous wave operation [3]. These advances promoted additional applications of QC lasers where cryogenic cooling was impossible or highly inconvenient. This dissertation presents comprehensive self-consistent models permitting the optimization of high operating temperature QC lasers. These models employ strategies counter to those used in designing low temperature devices and were used to design, fabricate, and demonstrate high-performance QC lasers. By self-consistently solving the temperature dependent threshold current density and heat equations, including temperature dependent thermal conductivities, phonon lifetimes, thermal "backfilling," thermionic emission, and energy level broadening, we calculated the effects of doping level, material choice, and waveguide layer thickness on the laser threshold performance

  20. A Model of Reading Comprehension in Chinese Elementary School Children

    ERIC Educational Resources Information Center

    Yeung, Pui-sze; Ho, Connie Suk-han; Chan, David Wai-ock; Chung, Kevin Kien-hoa; Wong, Yau-kai

    2013-01-01

    The relationships of reading-related skills (rapid naming, morphological awareness, syntactic skills, discourse skills, and verbal working memory) and word reading to reading comprehension were examined among 248 Chinese fourth graders in Hong Kong. Multiple regression analysis results showed that syntactic skills (word order knowledge,…

  1. Reading-Enhanced Word Problem Solving: A Theoretical Model

    ERIC Educational Resources Information Center

    Capraro, Robert M.; Capraro, Mary Margaret; Rupley, William H.

    2012-01-01

    There is a reciprocal relationship between mathematics and reading cognition. Metacognitive training within reading-enhanced problem solving should facilitate students developing an awareness of what good readers do when reading for meaning in solving mathematical problems enabling them to apply these strategies. The constructs for each cognitive…

  2. Repeated Reading: Testing Alternative Models for Efficient Implementation

    ERIC Educational Resources Information Center

    Lewis, Greg

    2012-01-01

    An investigation was conducted to determine the best criterion for advancement to a new reading passage during the commonly used classroom strategy of repeated reading. Knowing when to move students to a new passage during the repeated reading process was considered of value to teachers in efficiently using student learning time. The study also…

  3. Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

    SciTech Connect

    Lindskog, M. Wacker, A.; Wolf, J. M.; Liverini, V.; Faist, J.; Trinite, V.; Maisons, G.; Carras, M.; Aidam, R.; Ostendorf, R.

    2014-09-08

    We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents, agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device.

  4. Above-threshold numerical modeling of high-index-contrast photonic-crystal quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Napartovich, A. P.; Elkin, N. N.; Vysotsky, D. V.; Kirch, J.; Sigler, C.; Botez, D.; Mawst, L. J.; Belyanin, A.

    2015-03-01

    Three-dimensional above-threshold analyses of high-index-contrast (HC) photonic-crystal (PC) quantum-cascade-laser arrays (QCLA) structures, for operation at watt-range CW powers in a single spatial mode, have been performed. Threeelement HC-PC structures are formed by alternating active- antiguided and passive-guided regions along with respective metal-electrode spatial profiling. The 3-D numerical code takes into account absorption and edge-radiation losses. Rigrod's approximation is used for the gain. The specific feature of QCLA is that only the transverse component of the magnetic field sees the gain. Results of above-threshold laser modeling in various approximate versions of laser-cavity description are compared with the results of linear, full-vectorial modeling by using the COMSOL package. Additionally, modal gains for several higher-order optical modes, on a `frozen gain background' produced by the fundamental-mode, are computed by the Arnoldi algorithm. The gain spatial-hole burning effect results in growth of the competing modes' gain with drive current. Approaching the lasing threshold for a competing higher-order mode sets a limit on the single-mode operation range. The modal structure and stability are studied over a wide range in the variation of the inter-element widths. Numerical analyses predict that the proper choice of construction parameters ensures stable single-mode operation at high drive levels above threshold. The output power from a single- mode operated QCLA at a wavelength of 4.7 μm is predicted to be available at multi-watt levels, although this power may be restricted by thermal effects.

  5. Testing the generality of a trophic-cascade model for plague

    USGS Publications Warehouse

    Collinge, S.K.; Johnson, W.C.; Ray, C.; Matchett, R.; Grensten, J.; Cully, J.F.; Gage, K.L.; Kosoy, M.Y.; Loye, J.E.; Martin, A.P.

    2005-01-01

    Climate may affect the dynamics of infectious diseases by shifting pathogen, vector, or host species abundance, population dynamics, or community interactions. Black-tailed prairie dogs (Cynomys ludovicianus) are highly susceptible to plague, yet little is known about factors that influence the dynamics of plague epizootics in prairie dogs. We investigated temporal patterns of plague occurrence in black-tailed prairie dogs to assess the generality of links between climate and plague occurrence found in previous analyses of human plague cases. We examined long-term data on climate and plague occurrence in prairie dog colonies within two study areas. Multiple regression analyses revealed that plague occurrence in prairie dogs was not associated with climatic variables in our Colorado study area. In contrast, plague occurrence was strongly associated with climatic variables in our Montana study area. The models with most support included a positive association with precipitation in April-July of the previous year, in addition to a positive association with the number of "warm" days and a negative association with the number of "hot" days in the same year as reported plague events. We conclude that the timing and magnitude of precipitation and temperature may affect plague occurrence in some geographic areas. The best climatic predictors of plague occurrence in prairie dogs within our Montana study area are quite similar to the best climatic predictors of human plague cases in the southwestern United States. This correspondence across regions and species suggests support for a (temperature-modulated) trophic-cascade model for plague, including climatic effects on rodent abundance, flea abundance, and pathogen transmission, at least in regions that experience strong climatic signals. ?? 2005 EcoHealth Journal Consortium.

  6. Cooperative Learning Model toward a Reading Comprehensions on the Elementary School

    ERIC Educational Resources Information Center

    Murtono

    2015-01-01

    The purposes of this research are: (1) description of reading skill the students who join in CIRC learning model, Jigsaw learning model, and STAD learning model; (2) finding out the effective of learning model cooperative toward a reading comprehensions between the students who have high language logic and low language logic; and (3) finding out…

  7. Modeling regulatory cascades using Artificial Neural Networks: the case of transcriptional regulatory networks shaped during the yeast stress response.

    PubMed

    Manioudaki, Maria E; Poirazi, Panayiota

    2013-01-01

    Over the last decade, numerous computational methods have been developed in order to infer and model biological networks. Transcriptional networks in particular have attracted significant attention due to their critical role in cell survival. The majority of network inference methods use genome-wide experimental data to search for modules of genes with coherent expression profiles and common regulators, often ignoring the multi-layer structure of transcriptional cascades. Modeling methodologies on the other hand assume a given network structure and vary significantly in their algorithmic approach, ranging from over-simplified representations (e.g., Boolean networks) to detailed -but computationally expensive-network simulations (e.g., with differential equations). In this work we use Artificial Neural Networks (ANNs) to model transcriptional regulatory cascades that emerge during the stress response in Saccharomyces cerevisiae and extend in three layers. We confine the structure of the ANNs to match the structure of the biological networks as determined by gene expression, DNA-protein interaction and experimental evidence provided in publicly available databases. Trained ANNs are able to predict the expression profile of 11 target genes across multiple experimental conditions with a correlation coefficient >0.7. When time-dependent interactions between upstream transcription factors (TFs) and their indirect targets are also included in the ANNs, accurate predictions are achieved for 30/34 target genes. Moreover, heterodimer formation is taken into account. We show that ANNs can be used to (1) accurately predict the expression of downstream genes in a 3-layer transcriptional cascade based on the expression of their indirect regulators and (2) infer the condition- and time-dependent activity of various TFs as well as during heterodimer formation. We show that a three-layer regulatory cascade whose structure is determined by co-expressed gene modules and their

  8. The impact of the topology on cascading failures in a power grid model

    NASA Astrophysics Data System (ADS)

    Koç, Yakup; Warnier, Martijn; Mieghem, Piet Van; Kooij, Robert E.; Brazier, Frances M. T.

    2014-05-01

    Cascading failures are one of the main reasons for large scale blackouts in power transmission grids. Secure electrical power supply requires, together with careful operation, a robust design of the electrical power grid topology. Currently, the impact of the topology on grid robustness is mainly assessed by purely topological approaches, that fail to capture the essence of electric power flow. This paper proposes a metric, the effective graph resistance, to relate the topology of a power grid to its robustness against cascading failures by deliberate attacks, while also taking the fundamental characteristics of the electric power grid into account such as power flow allocation according to Kirchhoff laws. Experimental verification on synthetic power systems shows that the proposed metric reflects the grid robustness accurately. The proposed metric is used to optimize a grid topology for a higher level of robustness. To demonstrate its applicability, the metric is applied on the IEEE 118 bus power system to improve its robustness against cascading failures.

  9. Spontaneous Current-layer Fragmentation and Cascading Reconnection in Solar Flares. I. Model and Analysis

    NASA Astrophysics Data System (ADS)

    Bárta, Miroslav; Büchner, Jörg; Karlický, Marian; Skála, Jan

    2011-08-01

    Magnetic reconnection is commonly considered to be a mechanism of solar (eruptive) flares. A deeper study of this scenario reveals, however, a number of open issues. Among them is the fundamental question of how the magnetic energy is transferred from large, accumulation scales to plasma scales where its actual dissipation takes place. In order to investigate this transfer over a broad range of scales, we address this question by means of a high-resolution MHD simulation. The simulation results indicate that the magnetic-energy transfer to small scales is realized via a cascade of consecutively smaller and smaller flux ropes (plasmoids), analogous to the vortex-tube cascade in (incompressible) fluid dynamics. Both tearing and (driven) "fragmenting coalescence" processes are equally important for the consecutive fragmentation of the magnetic field (and associated current density) into smaller elements. At the later stages, a dynamic balance between tearing and coalescence processes reveals a steady (power-law) scaling typical of cascading processes. It is shown that cascading reconnection also addresses other open issues in solar-flare research, such as the duality between the regular large-scale picture of (eruptive) flares and the observed signatures of fragmented (chaotic) energy release, as well as the huge number of accelerated particles. Indeed, spontaneous current-layer fragmentation and the formation of multiple channelized dissipative/acceleration regions embedded in the current layer appear to be intrinsic to the cascading process. The multiple small-scale current sheets may also facilitate the acceleration of a large number of particles. The structure, distribution, and dynamics of the embedded potential acceleration regions in a current layer fragmented by cascading reconnection are studied and discussed.

  10. Hemofiltration with the Cascade system in an experimental porcine model of septic shock.

    PubMed

    Rimmelé, Thomas; Wey, Pierre-François; Bernard, Nicolas; Monchi, Mehran; Semenzato, Nicolas; Benatir, Farida; Boselli, Emmanuel; Etienne, Jérôme; Goudable, Joëlle; Chassard, Dominique; Bricca, Giampiero; Allaouchiche, Bernard

    2009-02-01

    High-volume hemofiltration (HVHF) has been suggested as an adjuvant treatment of septic shock because of its capacities to remove inflammatory mediators from blood. Nevertheless, HVHF presents some important drawbacks, such as the depletion of low molecular weight molecules (nutriments, vitamins, trace elements and antibiotics) due to the high ultrafiltration rate, or the significant financial cost and nursing workload due to the frequent changes of large amounts of expensive sterile substitution fluids. A new hemofiltration system called "Cascade" has been developed, allowing very high ultrafiltration rates (120 mL/kg/h) limiting these drawbacks by using a special extracorporeal circuit. The objective of this study was to assess the technical feasibility of the Cascade system and to compare its hemodynamic impact to that of the standard HVHF system. Twenty sepsis-induced pigs were randomized in two groups: one group was hemofiltered with the standard HVHF system and the other with the Cascade system during a six-hour session. No technical problems were observed with the Cascade system during the experiment. At the end of the experiment, colloid requirements (989 +/- 355 mL vs. 1913 +/- 538 mL, P = 0.006), epinephrine requirements (0.82 +/- 0.42 mg vs. 3.27 +/- 3.02 mg, P < 0.001), lactic acidosis (pH = 7.33 +/- 0.08 vs. 7.10 +/- 0.07, P < 0.001) and mean pulmonary arterial pressure were less pronounced in the Cascade group. These results suggest that Cascade hemofiltration is technically feasible and safe. Moreover, compared with standard HVHF, it can reduce the severity of porcine septic shock.

  11. Modeling of dilute nitride cascaded quantum well solar cells for high efficiency photovoltaics

    NASA Astrophysics Data System (ADS)

    Vijaya, G.; Alemu, A.; Freundlich, A.

    2013-03-01

    III-V Dilute Nitride multi-quantum well structures are currently promising candidates to achieve 1 sun efficiencies of <40% with multi-junction design (InGaP/ GaAs/ GaAsN/ Ge). Previously under the assumption of complete carrier collection from wells, we have shown that III-V Dilute Nitride GaAsN multi-quantum well (MQW) structures included in the intrinsic region of the third cell in a 4 junction configuration could yield 1 sun efficiencies greater than 40%. However for a conventional deep well design the characteristic carrier escape times could exceed that of radiative recombination hence limiting the current output of the cell, as has been indicated by prior experiments. In order to increase the current extraction here we evaluate the performance of a cascaded quantum well design whereby a thermally assisted resonant tunneling process is used to accelerate the carrier escape process (<30ps lifetime) and hence improve the photo generated carrier collection efficiency. The quantum efficiency of a p-i-n subcell where a periodic sequence of quantum wells with well and barrier thicknesses adjusted for the sequential extraction operation is calculated using a 2D drift diffusion model and taking into account absorption properties of resulting MQWs. The calculation also accounts for the E-field induced modifications of absorption properties and quantization in quantum wells. The results are then accounted for to calculate efficiencies for the proposed 4 junction design, and indicate potential for reaching efficiencies in excess of this structure is above 42% (1 sun) and above 50% (500 sun) AM1.5.

  12. A phosphorylation cascade in the basal ganglia of the mammalian brain: regulation by the D-1 dopamine receptor. A mathematical model of known biochemical reactions.

    PubMed

    Kebabian, J W

    1997-01-01

    Stimulation of the dopamine D-1 receptor in the corpus striatum initiates a cascade of biochemical events. These events include: activation of adenylate cyclase, stimulation of cAMP-dependent protein kinase, protein phosphorylation and inhibition of phosphoprotein phosphotase-1. This article presents and discusses a mathematical model of these biochemical events (and their dependence upon the concentration of cytosolic calcium). According to this model, the activity of calcineurin (which is regulated by the concentration of cytosolic calcium ions) counterbalances the activity of the "D-1 cascade". The combined activity of the "D-1 cascade" and calcineurin can regulate the activity of calcium- and calmodulin-dependent protein kinase II.

  13. Unsteady Aerodynamic Response of Oscillating Contra-Rotating Annular Cascades Part I: Description of Model and Mathematical Formulations

    NASA Astrophysics Data System (ADS)

    Namba, Masanobu; Nishino, Ryohei

    The purpose of this paper is to study the effect of neighboring blade rows on the unsteady aerodynamic response of oscillating cascade blades on the basis of a genuine three-dimensional model. To this end, mathematical formulations based on the lifting surface theory are developed for a pair of contra-rotating annular cascades of oscillating blades. The mechanism of frequency scattering of blade loadings and mode scattering of acoustic waves resulting from interaction between the blade rows in relative rotational motions is mathematically explained. Simultaneous integral equations for all frequency components of blade loadings are derived from the flow tangency condition on the blade surfaces of both blade rows. The validity of the computation codes is verified.

  14. Thinking outside the boxes: Using current reading models to assess and treat developmental surface dyslexia.

    PubMed

    Law, Caroline; Cupples, Linda

    2017-03-01

    Improving the reading performance of children with developmental surface dyslexia has proved challenging, with limited generalisation of reading skills typically reported after intervention. The aim of this study was to provide tailored, theoretically motivated intervention to two children with developmental surface dyslexia. Our objectives were to improve their reading performance, and to evaluate the utility of current reading models in therapeutic practice. Detailed reading and cognitive profiles for two male children with developmental surface dyslexia were compared to the results obtained by age-matched control groups. The specific area of single-word reading difficulty for each child was identified within the dual route model (DRM) of reading, following which a theoretically motivated intervention programme was devised. Both children showed significant improvements in single-word reading ability after training, with generalisation effects observed for untrained words. However, the assessment and intervention results also differed for each child, reinforcing the view that the causes and consequences of developmental dyslexia, even within subtypes, are not homogeneous. Overall, the results of the interventions corresponded more closely with the DRM than other current reading models, in that real word reading improved in the absence of enhanced nonword reading for both children.

  15. First-Grade Teachers' Response to Three Models of Professional Development in Reading

    ERIC Educational Resources Information Center

    Carlisle, Joanne F.; Cortina, Kai Schnabel; Katz, Lauren A.

    2011-01-01

    The purpose of this study was to compare 1st-grade teachers' responses to professional development (PD) programs in reading that differed in means and degree of support for teachers' learning and efforts to improve their reading instruction. We compared 3 models of PD: the 1st model provided only seminars for the teachers, the 2nd model provided…

  16. Modelling Normal and Impaired Letter Recognition: Implications for Understanding Pure Alexic Reading

    ERIC Educational Resources Information Center

    Chang, Ya-Ning; Furber, Steve; Welbourne, Stephen

    2012-01-01

    Letter recognition is the foundation of the human reading system. Despite this, it tends to receive little attention in computational modelling of single word reading. Here we present a model that can be trained to recognise letters in various spatial transformations. When presented with degraded stimuli the model makes letter confusion errors…

  17. Within-Year Oral Reading Fluency with CBM: A Comparison of Models

    ERIC Educational Resources Information Center

    Nese, Joseph F. T.; Biancarosa, Gina; Anderson, Daniel; Lai, Cheng-Fei; Alonzo, Julie; Tindal, Gerald

    2012-01-01

    This study examined the type of growth model that best fit within-year growth in oral reading fluency and between-student differences in growth. Participants were 2,465 students in grades 3-5. Hierarchical linear modeling (HLM) analyses modeled curriculum-based measurement (CBM) oral reading fluency benchmark measures in fall, winter, and spring…

  18. The utility of modeling word identification from visual input within models of eye movements in reading.

    PubMed

    Bicknell, Klinton; Levy, Roger

    2012-04-01

    Decades of empirical work have shown that a range of eye movement phenomena in reading are sensitive to the details of the process of word identification. Despite this, major models of eye movement control in reading do not explicitly model word identification from visual input. This paper presents a argument for developing models of eye movements that do include detailed models of word identification. Specifically, we argue that insights into eye movement behavior can be gained by understanding which phenomena naturally arise from an account in which the eyes move for efficient word identification, and that one important use of such models is to test which eye movement phenomena can be understood this way. As an extended case study, we present evidence from an extension of a previous model of eye movement control in reading that does explicitly model word identification from visual input, Mr. Chips (Legge, Klitz, & Tjan, 1997), to test two proposals for the effect of using linguistic context on reading efficiency.

  19. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    DOE PAGES

    Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

    2015-06-03

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less

  20. Modeling child-based theoretical reading constructs with struggling adult readers.

    PubMed

    Nanda, Alice O; Greenberg, Daphne; Morris, Robin

    2010-01-01

    This study examined whether measurement constructs behind reading-related tests for struggling adult readers are similar to what is known about measurement constructs for children. The sample included 371 adults reading between the third-and fifth-grade levels, including 127 men and 153 English speakers of other languages. Using measures of skills and subskills, confirmatory factor analyses were conducted to test child-based theoretical measurement models of reading: an achievement model of reading skills, a core deficit model of reading subskills, and an integrated model containing achievement and deficit variables. Although the findings present the best measurement models, the contribution of this article is the description of the difficulties encountered when applying child-based assumptions to developing measurement models for struggling adult readers.

  1. Crossover behavior in driven cascades.

    PubMed

    Burridge, James

    2013-09-01

    We propose a model which explains how power-law crossover behavior can arise in a system which is capable of experiencing cascading failure. In our model the susceptibility of the system to cascades is described by a single number, the propagation power, which measures the ease with which cascades propagate. Physically, such a number could represent the density of unstable material in a system, its internal connectivity, or the mean susceptibility of its component parts to failure. We assume that the propagation power follows an upward drifting Brownian motion between cascades, and drops discontinuously each time a cascade occurs. Cascades are described by a continuous state branching process with distributional properties determined by the value of the propagation power when they occur. In common with many cascading models, pure power-law behavior is exhibited at a critical level of propagation power, and the mean cascade size diverges. This divergence constrains large systems to the subcritical region. We show that as a result, crossover behavior appears in the cascade distribution when an average is performed over the distribution of propagation power. We are able to analytically determine the exponents before and after the crossover.

  2. A Model for Describing, Analysing and Investigating Cultural Understanding in EFL Reading Settings

    ERIC Educational Resources Information Center

    Porto, Melina

    2013-01-01

    This article describes a model used to explore cultural understanding in English as a foreign language reading in a developing country, namely Argentina. The model is designed to investigate, analyse and describe EFL readers' processes of cultural understanding in a specific context. Cultural understanding in reading is typically investigated…

  3. An Anatomically Constrained, Stochastic Model of Eye Movement Control in Reading

    ERIC Educational Resources Information Center

    McDonald, Scott A.; Carpenter, R. H. S.; Shillcock, Richard C.

    2005-01-01

    This article presents SERIF, a new model of eye movement control in reading that integrates an established stochastic model of saccade latencies (LATER; R. H. S. Carpenter, 1981) with a fundamental anatomical constraint on reading: the vertically split fovea and the initial projection of information in either visual field to the contralateral…

  4. White House Suggests Model Used in Reading to Elevate Math Skills

    ERIC Educational Resources Information Center

    Cavanagh, Sean

    2006-01-01

    This article discusses the Bush administration's aim to improve mathematics education through a suggested reading model. The White House is focusing on research to shape how students across the country are taught the most basic mathematical concepts. This undertaking would be modeled on the government's action toward reading, which includes the…

  5. Small-Group Reading Instruction: A Differentiated Teaching Model for Intermediate Readers, Grades 3-8

    ERIC Educational Resources Information Center

    Tyner, Beverly; Green, Sharon E.

    2005-01-01

    Teachers at the intermediate level can now take advantage of the small-group differentiated reading model introduced to the early learning community in Beverly Tyner's bestseller of 2004. This classroom-tested, research-based model supports reading, writing, and spelling as integrated processes. Differentiated instruction can help the reader meet…

  6. A Scalable Approach to Modeling Cascading Risk in the MDAP Network

    DTIC Science & Technology

    2014-05-01

    interdependencies and complexity. – Focus on funding interdependency • Network -centric approach (Brown and Owen, 2012; Raja et al., 2012) • Automated analysis for...program outcomes: “program-centric” + “program network approach” for acquisition and management. – Cascading effects recast as a sequential decision... Interdependency   Determiner Module  MNI_MOD MDAP  Network   Identifier Module  • Network and Program Centric analysis. • Novel Integration of methodologies for

  7. Cascade trailing-edge noise modeling using a mode-matching technique and the edge-dipole theory

    NASA Astrophysics Data System (ADS)

    Roger, Michel; François, Benjamin; Moreau, Stéphane

    2016-11-01

    An original analytical approach is proposed to model the broadband trailing-edge noise produced by high-solidity outlet guide vanes in an axial turbomachine. The model is formulated in the frequency domain and first in two dimensions for a preliminary assessment of the method. In a first step the trailing-edge noise sources of a single vane are shown to be equivalent to the onset of a so-called edge dipole, the direct field of which is expanded in a series of plane-wave modes. A criterion for the distance of the dipole to the trailing-edge and a scaling of its amplitude is defined to yield a robust model. In a second step the diffraction of each plane-wave mode is derived considering the cascade as an array of bifurcated waveguides and using a mode-matching technique. The cascade response is finally synthesized by summing the diffracted fields of all cut-on modes to yield upstream and downstream sound power spectral densities. The obtained spectral shapes are physically consistent and the present results show that upstream radiation is typically 3 dB higher than downstream radiation, which has been experimentally observed previously. Even though the trailing-edge noise sources are not vane-to-vane correlated their radiation is strongly determined by a cascade effect that consequently must be accounted for. The interest of the approach is that it can be extended to a three-dimensional annular configuration without resorting to a strip theory approach. As such it is a promising and versatile alternative to previously published methods.

  8. Developmental relations between vocabulary knowledge and reading comprehension: a latent change score modeling study.

    PubMed

    Quinn, Jamie M; Wagner, Richard K; Petscher, Yaacov; Lopez, Danielle

    2015-01-01

    The present study followed a sample of first-grade (N = 316, Mage = 7.05 at first test) through fourth-grade students to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and reading comprehension to test for the presence of leading and lagging influences. Univariate models indicated growth in vocabulary knowledge, and reading comprehension was determined by two parts: constant yearly change and change proportional to the previous level of the variable. Bivariate models indicated previous levels of vocabulary knowledge acted as leading indicators of reading comprehension growth, but the reverse relation was not found. Implications for theories of developmental relations between vocabulary and reading comprehension are discussed.

  9. Developmental Relations Between Vocabulary Knowledge and Reading Comprehension: A Latent Change Score Modeling Study

    PubMed Central

    Quinn, Jamie M.; Wagner, Richard K.; Petscher, Yaacov; Lopez, Danielle

    2014-01-01

    The present study followed a sample of first grade students (N = 316, mean age = 7.05 at first test) through fourth grade to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and reading comprehension to test for the presence of leading and lagging influences. Univariate models indicated growth in vocabulary knowledge and reading comprehension was determined by two parts: constant yearly change and change proportional to the previous level of the variable. Bivariate models indicated previous levels of vocabulary knowledge acted as leading indicators of reading comprehension growth, but the reverse relation was not found. Implications for theories of developmental relations between vocabulary and reading comprehension are discussed. PMID:25201552

  10. Modeling Growth of SAT Reading Performance Using Repeated Measures Data

    ERIC Educational Resources Information Center

    Deng, Hui; Wiley, Andrew

    2008-01-01

    Presented at the Annual National Council on Measurement in Education (NCME) in New York in March 2008. This presentation explores the growth trajectory of the SAT Reading scores and examine what demographics and variation may cause changes and affect growth.

  11. When Interrupted Intervention Leads to Failure: A Correlation Study of the Three-Tiered Reading Model in Grades K-2

    ERIC Educational Resources Information Center

    Weis, Beverly Lynn

    2012-01-01

    The three-tiered reading model is a widely practiced instructional scheme that moves students in and out of reading intervention groups during the school year. Though designed to treat students who need extra help learning to read, this interruption of reading interventions may hinder some students' progress. The purpose of this study was to…

  12. Cognitive component of componential model of reading applied to different orthographies.

    PubMed

    Joshi, R Malatesha; Tao, Sha; Aaron, P G; Quiroz, Blanca

    2012-01-01

    Whether the simple view of reading (SVR) as incorporated in the componential model of reading (CMR) is applicable to other orthographies than English was explored in this study. Spanish, with transparent orthography and Chinese, with opaque orthography were selected because of their diverse characteristics. The first part reports a study of students from grades 2 and 3, whose home language and medium of instruction was Spanish, and were administered tests of decoding, listening, and reading comprehension. A comparison group of 49 children from Grade 2, 54 children from Grade 3, and 55 children from Grade 4, whose home language and instruction was English, were also administered tests of decoding, listening, and reading comprehension. Multiple regression analysis showed that approximately 60% of the variance in reading comprehension of Spanish participants and 50% of the variance in reading comprehension of English participants were explained by decoding and listening comprehension. Furthermore, the performance of third grade Spanish participants resembled that of fourth grade English-speaking participants. In the second study, 102 Chinese students from Grade 2 and 106 students from Grade 4 were administered tasks of Chinese character recognition, reading fluency, listening, and reading comprehension. Multiple regression analyses showed character recognition and listening comprehension accounted for 25% and 42% of the variance in Chinese reading comprehension at Grades 2 and 4 respectively. These results indicate that the simple view of reading is applicable to writing systems other than that of English.

  13. Resonant Cascaded Downconversion

    SciTech Connect

    Weedbrook, Christian; Parrett, Ben; Kheruntsyan, Karen; Drummond, Peter; Pooser, Raphael C; Pfister, Olivier

    2012-01-01

    We analyze an optical parametric oscillator (OPO) in which cascaded down-conversion occurs inside a cavity resonant for all modes but the initial pump. Due to the resonant cascade design, the OPO presents two {chi}{sup (2)}-level oscillation thresholds that are therefore much lower than for a {chi}{sup (3)} OPO. This is promising for reaching the regime of an effective third-order nonlinearity well above both thresholds. Such a {chi}{sup (2)} cascaded device also has potential applications in frequency conversion to far-infrared regimes. But, most importantly, it can generate novel multipartite quantum correlations in the output radiation, which represent a step beyond squeezed or entangled light. The output can be highly non-Gaussian and therefore not describable by any semiclassical model. In this paper, we derive quantum stochastic equations in the positive-P representation and undertake an analysis of steady-state and dynamical properties of this system.

  14. Language Modeling and Reading Achievement: Variations across Different Types of Language Instruction Programs

    ERIC Educational Resources Information Center

    López, Francesca; Scanlan, Martin; Gorman, Brenda K.

    2015-01-01

    This study investigated the degree to which the quality of teachers' language modeling contributed to reading achievement for 995 students, both English language learners and native English speakers, across developmental bilingual, dual language, and monolingual English classrooms. Covariates included prior reading achievement, gender, eligibility…

  15. What Is Wrong with ANOVA and Multiple Regression? Analyzing Sentence Reading Times with Hierarchical Linear Models

    ERIC Educational Resources Information Center

    Richter, Tobias

    2006-01-01

    Most reading time studies using naturalistic texts yield data sets characterized by a multilevel structure: Sentences (sentence level) are nested within persons (person level). In contrast to analysis of variance and multiple regression techniques, hierarchical linear models take the multilevel structure of reading time data into account. They…

  16. Toward an Interactive Model of Reading. CHIP Technical Report No. 56.

    ERIC Educational Resources Information Center

    Rumelhart, David E.

    Reading is a process that bridges the distinction between perceptual and cognitive processes but the formalisms of the information processing approach to the study of reading apply most naturally either to models assuming a series of noninteracting stages of information processing or to a set of independent parallel processing units. This paper…

  17. Validation of a Cognitive Diagnostic Model across Multiple Forms of a Reading Comprehension Assessment

    ERIC Educational Resources Information Center

    Clark, Amy K.

    2013-01-01

    The present study sought to fit a cognitive diagnostic model (CDM) across multiple forms of a passage-based reading comprehension assessment using the attribute hierarchy method. Previous research on CDMs for reading comprehension assessments served as a basis for the attributes in the hierarchy. The two attribute hierarchies were fit to data from…

  18. Modeling the Relationships among Reading Instruction, Motivation, Engagement, and Achievement for Adolescents

    ERIC Educational Resources Information Center

    Guthrie, John T.; Klauda, Susan Lutz; Ho, Amy N.

    2013-01-01

    This study modeled the interrelationships of reading instruction, motivation, engagement, and achievement in two contexts, employing data from 1,159 seventh graders. In the traditional reading/language arts (R/LA) context, all students participated in traditional R/LA instruction. In the intervention R/LA context, 854 students from the full sample…

  19. Cognitive Component of Componential Model of Reading Applied to Different Orthographies

    ERIC Educational Resources Information Center

    Joshi, R. Malatesha; Tao, Sha; Aaron, P. G.; Quiroz, Blanca

    2012-01-01

    Whether the simple view of reading (SVR) as incorporated in the componential model of reading (CMR) is applicable to other orthographies than English was explored in this study. Spanish, with transparent orthography and Chinese, with opaque orthography were selected because of their diverse characteristics. The first part reports a study of…

  20. Lenses on Reading: An Introduction to Theories and Models. Second Edition

    ERIC Educational Resources Information Center

    Tracey, Diane H.; Morrow, Lesley Mandel

    2012-01-01

    This widely adopted text explores key theories and models that frame reading instruction and research. Readers learn why theory matters in designing and implementing high-quality instruction and research; how to critically evaluate the assumptions and beliefs that guide their own work; and what can be gained by looking at reading through multiple…

  1. Howling about Trophic Cascades

    ERIC Educational Resources Information Center

    Kowalewski, David

    2012-01-01

    Following evolutionary theory and an agriculture model, ecosystem research has stressed bottom-up dynamics, implying that top wild predators are epiphenomenal effects of more basic causes. As such, they are assumed expendable. A more modern co-evolutionary and wilderness approach--trophic cascades--instead suggests that top predators, whose…

  2. Investigation of Positively Curved Blade in Compressor Cascade Based on Transition Model

    NASA Astrophysics Data System (ADS)

    Chen, Shaowen; Lan, Yunhe; Zhou, Zhihua; Wang, Songtao

    2016-06-01

    Experiment and numerical simulation of flow transition in a compressor cascade with positively curved blade is carried out in a low speed. In the experimental investigation, the outlet aerodynamic parameters are measured using a five-hole aerodynamic probe, and an ink-trace flow visualization is applied to the cascade surface. The effects of transition flow on the boundary layer development, three-dimensional flow separation and aerodynamic performance are studied. The feasibility of a commercial computational fluid dynamic code is validated and the numerical results show a good agreement with experimental data. The blade-positive curving intensifies the radial force from the endwalls to the mid-span near the suction surface, which leads to the smaller scope of the intermittent region, the lesser extents of turbulence intensity and the shorter radial height of the separation bubble near the endwalls, but has little influence on the flow near the mid-span. The large passage vortex is divided into two smaller shedding vortexes under the impact of the radial pressure gradient due to the positively curved blade. The new concentrated shedding vortex results in an increase in the turbulence intensity and secondary flow loss of the corresponding region.

  3. Long term reliability study and life time model of quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Xie, Feng; Nguyen, Hong-Ky; Leblanc, Herve; Hughes, Larry; Wang, Jie; Wen, Jianguo; Miller, Dean J.; Lascola, Kevin

    2016-09-01

    Here, we present results of quantum cascade laser lifetime tests under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 × 106 device hours. The longest single device aging time was 46 500 hours without failure in the room temperature aging test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Failure mode analyses revealed that thermally induced oxidation of InP in the semi-insulating layer is the cause of failure. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. The mean time to failure of the quantum cascade lasers operating at a typical condition with the current density of 5 kA/cm2 and heat-sink temperature of 25 °C is expected to be 809 000 hours.

  4. Integrated Surface and Ground Water modeling of a tank cascaded sub basin using physically based model in a semi-arid region

    NASA Astrophysics Data System (ADS)

    Ilampooranan, I.; Muthiah, K.; Athikesavan, R.

    2013-05-01

    Hydrological Modeling of tank (small reservoirs) cascaded sub-basin of a semi-arid region is a complex process. Physically based approach can simulate the various processes in surface, unsaturated and saturated ground water zones of such sub basin in an integrated manner. The objectives of the study are (i) to characterize the study area to replicate the physical conditions of surface and saturated zones (ii) to carryout overland flow routing of a tank cascaded basin using physically based modular approach (iii) To simulate the ground water levels in the unconfined aquifer (iv) to study the surface and groundwater dynamics on incorporation of tank cascades in the integrated model. An integrated, physically based model MIKE 11 & MIKE SHE was applied to study the hydrological processes of a tank cascaded semi-arid basin in which flow through tanks were modeled using MIKE 11 and coupled with MIKE SHE in-order to best represent the surface water dynamics in a distributed manner. Sindapalli Uppodai sub-basin, Southern Tamilnadu, India is chosen as study area. There are 15 tanks connected in series forming a tank cascade. Other tanks and depressions in the sub basin are also considered for the study and their effectiveness were analysed. DEM was obtained from SRTM data. The maps such as drainage network, land use and soil are prepared. Soil sampling was carried out. The time series data of rainfall and climate parameters are given as input. The characterization of unconfined aquifer formation was done by Geo-Resistivity survey. 71 observation and pumping wells are monitored within and periphery of sub basin which are used for calibration of the model. The flow routing over the land is done by MIKE SHE's Overland Flow Module, using the diffusive wave approximation of the Saint Venant equation. The hydrograph of routed runoff from the tank cascaded catchment was obtained. The spatial and temporal variation of hydraulic head of the saturated ground water zone is simulated

  5. Model-Predictive Cascade Mitigation in Electric Power Systems With Storage and Renewables-Part II: Case-Study

    SciTech Connect

    Almassalkhi, MR; Hiskens, IA

    2015-01-01

    The novel cascade-mitigation scheme developed in Part I of this paper is implemented within a receding-horizon model predictive control (MPC) scheme with a linear controller model. This present paper illustrates the MPC strategy with a case-study that is based on the IEEE RTS-96 network, though with energy storage and renewable generation added. It is shown that the MPC strategy alleviates temperature overloads on transmission lines by rescheduling generation, energy storage, and other network elements, while taking into account ramp-rate limits and network limitations. Resilient performance is achieved despite the use of a simplified linear controller model. The MPC scheme is compared against a base-case that seeks to emulate human operator behavior.

  6. Cross sections of proton- and neutron-induced reactions by the Liège intranuclear cascade model

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou

    2016-06-01

    The purpose of the paper is mainly to test the validity of the Liège intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of 3He display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (10Be and 26Al) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of 26Al from reactions n + 27Al, n + 28Si, and n + 40Ca and those of 10Be from reactions n + 16O and n + 28Si. The results also show a good agreement with a posteriori excitation functions.

  7. The Implementation of C-ID, R2D2 Model on Learning Reading Comprehension

    ERIC Educational Resources Information Center

    Rayanto, Yudi Hari; Rusmawan, Putu Ngurah

    2016-01-01

    The purposes of this research are to find out, (1) whether C-ID, R2D2 model is effective to be implemented on learning Reading comprehension, (2) college students' activity during the implementation of C-ID, R2D2 model on learning Reading comprehension, and 3) college students' learning achievement during the implementation of C-ID, R2D2 model on…

  8. Microdomain [Ca(2+)] Fluctuations Alter Temporal Dynamics in Models of Ca(2+)-Dependent Signaling Cascades and Synaptic Vesicle Release.

    PubMed

    Weinberg, Seth H

    2016-03-01

    Ca(2+)-dependent signaling is often localized in spatially restricted microdomains and may involve only 1 to 100 Ca(2+) ions. Fluctuations in the microdomain Ca(2+) concentration (Ca(2+)) can arise from a wide range of elementary processes, including diffusion, Ca(2+) influx, and association/dissociation with Ca(2+) binding proteins or buffers. However, it is unclear to what extent these fluctuations alter Ca(2+)-dependent signaling. We construct Markov models of a general Ca(2+)-dependent signaling cascade and Ca(2+)-triggered synaptic vesicle release. We compare the hitting (release) time distribution and statistics for models that account for [Ca(2+)] fluctuations with the corresponding models that neglect these fluctuations. In general, when Ca(2+) fluctuations are much faster than the characteristic time for the signaling event, the hitting time distributions and statistics for the models with and without Ca(2+) fluctuation are similar. However, when the timescale of Ca(2+) fluctuations is on the same order as the signaling cascade or slower, the hitting time mean and variability are typically increased, in particular when the average number of microdomain Ca(2+) ions is small, a consequence of a long-tailed hitting time distribution. In a model of Ca(2+)-triggered synaptic vesicle release, we demonstrate the conditions for which [Ca(2+)] fluctuations do and do not alter the distribution, mean, and variability of release timing. We find that both the release time mean and variability can be increased, demonstrating that Ca(2+) fluctuations are an important aspect of microdomain Ca(2+) signaling and further suggesting that Ca(2+) fluctuations in the presynaptic terminal may contribute to variability in synaptic vesicle release and thus variability in neuronal spiking.

  9. Computer modeling of a two-junction, monolithic cascade solar cell

    NASA Technical Reports Server (NTRS)

    Lamorte, M. F.; Abbott, D.

    1979-01-01

    The theory and design criteria for monolithic, two-junction cascade solar cells are described. The departure from the conventional solar cell analytical method and the reasons for using the integral form of the continuity equations are briefly discussed. The results of design optimization are presented. The energy conversion efficiency that is predicted for the optimized structure is greater than 30% at 300 K, AMO and one sun. The analytical method predicts device performance characteristics as a function of temperature. The range is restricted to 300 to 600 K. While the analysis is capable of determining most of the physical processes occurring in each of the individual layers, only the more significant device performance characteristics are presented.

  10. Modelling of multijunction cascade photovoltaics for space applications. M.S. Thesis, 1988

    NASA Technical Reports Server (NTRS)

    Educato, James Louis

    1987-01-01

    An alternative class of photovoltaics was presented, which is designed to overcome two problem areas with conventional cascade designs: poor upper subcell performance and lossy intercell ohmic contact (IOC). It was shown that upper subcell quality can be improved by incorporating additional junctions into the upper subcell and that the problems with monolithic IOCs may be circumvented by using complementary pairs of three-terminal cells or a 1 x 2 voltage-matched configuration. Realistic simulations show that AlGaAs-GaAs and AlGaAs-InGaAs multijunction, multiband-gap solar cells (MJSC) may achieve benginning-of-life (BOL) one-sun, AMO efficiencies of 26 and 28 percent, respectively. Complementary cells made in the AlGaAs-InGaAs system can achieve BOL one-sun AMO efficiencies in excess of 27 percent. Seven-layer MJSCs are most advantageous for space applications due to their superior tolerance to radiation degradation.

  11. Hemispheric Dissociation and Dyslexia in a Computational Model of Reading

    ERIC Educational Resources Information Center

    Monaghan, Padraic; Shillcock, Richard

    2008-01-01

    There are several causal explanations for dyslexia, drawing on distinctions between dyslexics and control groups at genetic, biological, or cognitive levels of description. However, few theories explicitly bridge these different levels of description. In this paper, we review a long-standing theory that some dyslexics' reading impairments are due…

  12. Oral Language and Reading Success: A Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Beron, Kurt J.; Farkas, George

    2004-01-01

    Oral language skills and habits may serve as important resources for success or failure in school-related tasks such as learning to read. This article tests this hypothesis utilizing a unique data set, the original Woodcock-Johnson Psycho-Educational Battery-Revised norming sample. This article assesses the importance of oral language by focusing…

  13. A Model of Reading Comprehension of Geometry Proof

    ERIC Educational Resources Information Center

    Yang, Kai-Lin; Lin, Fou-Lai

    2008-01-01

    This study aims to investigate a construct of reading comprehension of geometry proof (RCGP). The research aims to investigate (a) the facets composing RCGP, and (b) the structure of these facets. Firstly, we conceptualize this construct with relevant literature and on the basis of the discrimination between the logical and the epistemic meanings…

  14. Using the CIPP Model to Evaluate Reading Instruction.

    ERIC Educational Resources Information Center

    Nicholson, Tom

    1989-01-01

    Presents an approach to evaluation of reading instruction called CIPP (context, input, process, product), including: methods for discovering the needs of each student, getting input from students and colleagues concerning possible action, implementing evaluation in the process of instruction, and then carrying out an evaluation of the final…

  15. Phonotactic Constraints: Implications for Models of Oral Reading in Russian

    ERIC Educational Resources Information Center

    Ulicheva, Anastasia; Coltheart, Max; Saunders, Steven; Perry, Conrad

    2016-01-01

    The present article investigates how phonotactic rules constrain oral reading in the Russian language. The pronunciation of letters in Russian is regular and consistent, but it is subject to substantial phonotactic influence: the position of a phoneme and its phonological context within a word can alter its pronunciation. In Part 1 of the article,…

  16. Joint Book Reading and Receptive Vocabulary: A Parallel Process Model

    ERIC Educational Resources Information Center

    Meng, Christine

    2016-01-01

    The purpose of the present study was to understand the reciprocal, bidirectional longitudinal relation between joint book reading and English receptive vocabulary. To address the research goals, a nationally representative sample of Head Start children, the Head Start Family and Child Experiences Survey (2003 cohort), was used for analysis. The…

  17. Spatial Coding and Discourse Models during Text Reading.

    ERIC Educational Resources Information Center

    Baccino, Thierry; Pynte, Joel

    1994-01-01

    Studied representation of text content and representation of the surface form of the text in two studies of native French speakers. Twenty-five subjects (aged 23-30) participated in Experiment 1, and 40 subjects (aged 23-30) participated in Experiment 2. Data confirm that readers retain the spatial location of words read. (Contains 18 references.)…

  18. Theoretical Models and Processes of Reading. Fourth Edition.

    ERIC Educational Resources Information Center

    Ruddell, Robert B., Ed.; And Others

    Serving as a source of questions for researchers to investigate and a resource for professors and their students, this book presents 51 essays that discuss where the reading field has been, is now, and might be going. More than 80% of the essays are new or revised from the third edition. Essays in the book include "Professional Connections:…

  19. Mapping hazards from glacier lake outburst floods based on modelling of process cascades at Lake 513, Carhuaz, Peru

    NASA Astrophysics Data System (ADS)

    Schneider, D.; Huggel, C.; Cochachin, A.; Guillén, S.; García, J.

    2014-01-01

    Recent warming has had enormous impacts on glaciers and high-mountain environments. Hazards have changed or new ones have emerged, including those from glacier lakes that form as glaciers retreat. The Andes of Peru have repeatedly been severely impacted by glacier lake outburst floods in the past. An important recent event occurred in the Cordillera Blanca in 2010 when an ice avalanche impacted a glacier lake and triggered an outburst flood that affected the downstream communities and city of Carhuaz. In this study we evaluate how such complex cascades of mass movement processes can be simulated coupling different physically-based numerical models. We furthermore develop an approach that allows us to elaborate corresponding hazard maps according to existing guidelines for debris flows and based on modelling results and field work.

  20. Eco-hydrologic model cascades: Simulating land use and climate change impacts on hydrology, hydraulics and habitats for fish and macroinvertebrates.

    PubMed

    Guse, Björn; Kail, Jochem; Radinger, Johannes; Schröder, Maria; Kiesel, Jens; Hering, Daniel; Wolter, Christian; Fohrer, Nicola

    2015-11-15

    Climate and land use changes affect the hydro- and biosphere at different spatial scales. These changes alter hydrological processes at the catchment scale, which impact hydrodynamics and habitat conditions for biota at the river reach scale. In order to investigate the impact of large-scale changes on biota, a cascade of models at different scales is required. Using scenario simulations, the impact of climate and land use change can be compared along the model cascade. Such a cascade of consecutively coupled models was applied in this study. Discharge and water quality are predicted with a hydrological model at the catchment scale. The hydraulic flow conditions are predicted by hydrodynamic models. The habitat suitability under these hydraulic and water quality conditions is assessed based on habitat models for fish and macroinvertebrates. This modelling cascade was applied to predict and compare the impacts of climate- and land use changes at different scales to finally assess their effects on fish and macroinvertebrates. Model simulations revealed that magnitude and direction of change differed along the modelling cascade. Whilst the hydrological model predicted a relevant decrease of discharge due to climate change, the hydraulic conditions changed less. Generally, the habitat suitability for fish decreased but this was strongly species-specific and suitability even increased for some species. In contrast to climate change, the effect of land use change on discharge was negligible. However, land use change had a stronger impact on the modelled nitrate concentrations affecting the abundances of macroinvertebrates. The scenario simulations for the two organism groups illustrated that direction and intensity of changes in habitat suitability are highly species-dependent. Thus, a joined model analysis of different organism groups combined with the results of hydrological and hydrodynamic models is recommended to assess the impact of climate and land use changes on

  1. Reciprocal Effects between Intrinsic Reading Motivation and Reading Competence? A Cross-Lagged Panel Model for Academic Track and Nonacademic Track Students

    ERIC Educational Resources Information Center

    Schaffner, Ellen; Philipp, Maik; Schiefele, Ulrich

    2016-01-01

    Previous research has demonstrated positive relations between intrinsic reading motivation and reading competence. However, the causal direction of these relations and the moderating role of relevant background variables (e.g., students' achievement level) are not well understood. In the present study, a cross-lagged panel model was applied to…

  2. Information cascade on networks

    NASA Astrophysics Data System (ADS)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  3. A possible basic cortical microcircuit called "cascaded inhibition." Results from cortical network models and recording experiments from striate simple cells.

    PubMed

    Wörgötter, F; Nelle, E; Li, B; Wang, L; Diao, Y

    1998-10-01

    The robust behavior, the degree of response linearity, and the aspect of contrast gain control in visual cortical simple cells are (amongst others) the result of the interplay between excitatory and inhibitory afferent and intracortical connections. The goal of this study was to suggest a simple intracortical connection pattern, which could also play a role in other cortical substructures, in order to generically obtain these desired effects within large physiological parameter ranges. To this end we explored the degree of linearity of spatial summation in visual simple cells experimentally and in different models based on half-wave rectifying cells ("push-pull models"). Visual cortical push-pull connection schemes originated from antagonistic motor-control models. Thus, this model class is widely applicable but normally requires a rather specific design. On the other hand we showed that a more generic version of a push-pull model, the so-called cascaded inhibitory intracortical connection scheme, which we implemented in a biologically realistic simulation, naturally explains much of the experimental data. We investigated the influence of the afferent and intracortical connection structure on the measured linearity of spatial summation in simple cells. The analysis made use of the relative modulation measure, which is easy to apply but is limited to moving sinusoidal grating stimuli. We introduced two basic push-pull models, where the order of threshold nonlinearity and linear summation is reversed. Very little difference is observed with the relative modulation measure for these models. Alterative models, like half-wave squaring models, were also briefly discussed. Of all model parameters, the ratio of excitation to inhibition in the simple cell exerts the most crucial influence on the relative modulation. Linearity deteriorates as soon as excitatory and inhibitory inputs are imbalanced and the relative modulation drops. This prediction was tested experimentally

  4. Cascade aeroacoustics including steady loading effects

    NASA Astrophysics Data System (ADS)

    Chiang, Hsiao-Wei D.; Fleeter, Sanford

    A mathematical model is developed to analyze the effects of airfoil and cascade geometry, steady aerodynamic loading, and the characteristics of the unsteady flow field on the discrete frequency noise generation of a blade row in an incompressible flow. The unsteady lift which generates the noise is predicted with a complex first-order cascade convected gust analysis. This model was then applied to the Gostelow airfoil cascade and variations, demonstrating that steady loading, cascade solidity, and the gust direction are significant. Also, even at zero incidence, the classical flat plate cascade predictions are unacceptable.

  5. Retrofitting Non-Cognitive-Diagnostic Reading Assessment under the Generalized DINA Model Framework

    ERIC Educational Resources Information Center

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    Cognitive diagnosis models (CDMs) are psychometric models developed mainly to assess examinees' specific strengths and weaknesses in a set of skills or attributes within a domain. By adopting the Generalized-DINA model framework, the recently developed general modeling framework, we attempted to retrofit the PISA reading assessments, a…

  6. AAC Modeling with the iPad during Shared Storybook Reading Pilot Study

    ERIC Educational Resources Information Center

    Sennott, Samuel C.; Mason, Linda H.

    2016-01-01

    This pilot study describes an intervention package, MODELER for Read and Talk, designed to provide enriched language interaction for children with complex communication needs who require augmentative and alternative communication (AAC). MODELER (Model, Encourage, Respond) includes (a) modeling AAC as you speak, (b) encouraging communication…

  7. PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0

    NASA Astrophysics Data System (ADS)

    Sa, Ben-Hao; Zhou, Dai-Mei; Yan, Yu-Liang; Dong, Bao-Guo; Cai, Xu

    2013-05-01

    We have updated the parton and hadron cascade model PACIAE 2.0 (cf. Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Xiao-Mei Li, Sheng-Qin Feng, Bao-Guo Dong, Xu Cai, Comput. Phys. Comm. 183 (2012) 333.) to the new issue of PACIAE 2.1. The PACIAE model is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum pT is randomly sampled in the string fragmentation, the px and py components are originally put on the circle with radius pT randomly. Now it is put on the circumference of ellipse with half major and minor axes of pT(1+δp) and pT(1-δp), respectively, in order to better investigate the final state transverse momentum anisotropy. New version program summaryManuscript title: PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0 Authors: Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Bao-Guo Dong, and Xu Cai Program title: PACIAE version 2.1 Journal reference: Catalogue identifier: Licensing provisions: none Programming language: FORTRAN 77 or GFORTRAN Computer: DELL Studio XPS and others with a FORTRAN 77 or GFORTRAN compiler Operating system: Linux or Windows with FORTRAN 77 or GFORTRAN compiler RAM: ≈ 1GB Number of processors used: Supplementary material: Keywords: relativistic nuclear collision; PYTHIA model; PACIAE model Classification: 11.1, 17.8 External routines/libraries: Subprograms used: Catalogue identifier of previous version: aeki_v1_0* Journal reference of previous version: Comput. Phys. Comm. 183(2012)333. Does the new version supersede the previous version?: Yes* Nature of problem: PACIAE is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum(pT)is randomly sampled in the string fragmentation, thepxandpycomponents are randomly placed on the circle with radius ofpT. This strongly cancels the final state transverse momentum asymmetry developed dynamically. Solution method: Thepxandpycomponent of hadron in the string fragmentation is now randomly placed on the circumference of an ellipse with

  8. The zoom lens of attention: Simulating shuffled versus normal text reading using the SWIFT model.

    PubMed

    Schad, Daniel J; Engbert, Ralf

    2012-04-01

    Assumptions on the allocation of attention during reading are crucial for theoretical models of eye guidance. The zoom lens model of attention postulates that attentional deployment can vary from a sharp focus to a broad window. The model is closely related to the foveal load hypothesis, i.e., the assumption that the perceptual span is modulated by the difficulty of the fixated word. However, these important theoretical concepts for cognitive research have not been tested quantitatively in eye movement models. Here we show that the zoom lens model, implemented in the SWIFT model of saccade generation, captures many important patterns of eye movements. We compared the model's performance to experimental data from normal and shuffled text reading. Our results demonstrate that the zoom lens of attention might be an important concept for eye movement control in reading.

  9. Dimuon radiation at relativistic energies available at the CERN Super Proton Synchrotron within a (3 + 1)D hydrodynamic + cascade model

    SciTech Connect

    Santini, E.; Steinheimer, J.; Bleicher, M.; Schramm, S.

    2011-07-15

    We analyze dilepton emission from hot and dense matter using a hybrid approach based on the ultrarelativistic quantum molecular dynamics (UrQMD) transport model with an intermediate hydrodynamic stage for the description of heavy-ion collisions at relativistic energies. During the hydrodynamic stage, the production of lepton pairs is described by radiation rates for a strongly interacting medium in thermal equilibrium. In the low-mass region, hadronic thermal emission is evaluated by assuming vector meson dominance including in-medium modifications of the {rho} meson spectral function through scattering from nucleons and pions in the heat bath. In the intermediate-mass region, the hadronic rate is essentially determined by multipion annihilation processes. Emission from quark-antiquark annihilation in the quark gluon plasma (QGP) is taken into account as well. When the system is sufficiently dilute, the hydrodynamic description breaks down and a transition to a final cascade stage is performed. In this stage dimuon emission is evaluated as commonly done in transport models. By focusing on the enhancement with respect to the contribution from long-lived hadron decays after freezeout observed at the SPS in the low-mass region of the dilepton spectra, the relative importance of the different thermal contributions and of the two dynamical stages is investigated. We find that three separated regions can be identified in the invariant mass spectra. Whereas the very low and the intermediate-mass regions mostly receive contribution from the thermal dilepton emission, the region around the vector meson peak is dominated by the cascade emission. Above the {rho}-peak region the spectrum is driven by QGP radiation. Analysis of the dimuon transverse mass spectra reveals that the thermal hadronic emission shows an evident mass ordering not present in the emission from the QGP. A comparison of our calculation to recent acceptance-corrected NA60 data on invariant as well as

  10. Recent topographic evolution and erosion of the deglaciated Washington Cascades inferred from a stochastic landscape evolution model

    NASA Astrophysics Data System (ADS)

    Moon, S.; Shelef, E.; Hilley, G. E.

    2013-12-01

    The Washington Cascades is currently in topographic and erosional disequilibrium after deglaciation occurred around 11- 17 ka ago. The topography still shows the features inherited from prior alpine glacial processes (e.g., cirques, steep side-valleys, and flat valley bottoms), though postglacial processes are currently denuding this landscape. Our previous study in this area calculated the thousand-year-timescale denudation rates using cosmogenic 10Be concentration (CRN-denudation rates), and showed that they were ~ four times higher than million-year-timescale uplift rates. In addition, the spatial distribution of denudation rates showed a good correlation with a factor-of-ten variation in precipitation. We interpreted this correlation as reflecting the sensitivity of landslide triggering in over-steepened deglaciated topography to precipitation, which produced high denudation rates in wet areas that experienced frequent landsliding. We explored this interpretation using a model of postglacial surface processes that predicts the evolution of the topography and denudation rates within the deglaciated Washington Cascades. Specifically, we used the model to understand the controls on and timescales of landscape response to changes in the surface process regime after deglaciation. The postglacial adjustment of this landscape is modeled using a geomorphic-transport-law-based numerical model that includes processes of river incision, hillslope diffusion, and stochastic landslides. The surface lowering due to landslides is parameterized using a physically-based slope stability model coupled to a stochastic model of the generation of landslides. The model parameters of river incision and stochastic landslides are calibrated based on the rates and distribution of thousand-year-timescale denudation rates measured from cosmogenic 10Be isotopes. The probability distribution of model parameters required to fit the observed denudation rates shows comparable ranges from

  11. A domain model of a clinical reading center - Design and implementation.

    PubMed

    Lotz, Gunnar; Peters, Tobias; Zrenner, Eberhart; Wilke, Robert

    2010-01-01

    In clinical trials huge amounts of raw data are generated. Often these data are submitted to reading centers for being analyzed by experts of that particular type of examination. Although the installment of a reading center can raise the overall quality, they also introduce additional complexity to the management and conduction of a clinical trial. Software can help to handle this complexity. Domain-driven-design is one concept to tackle software development in such complex domains. Here we present our domain model for a clinical reading center, as well as its actual implementation utilizing the Nuxeo enterprise content management system.

  12. A cascaded QSAR model for efficient prediction of overall power conversion efficiency of all-organic dye-sensitized solar cells.

    PubMed

    Li, Hongzhi; Zhong, Ziyan; Li, Lin; Gao, Rui; Cui, Jingxia; Gao, Ting; Hu, Li Hong; Lu, Yinghua; Su, Zhong-Min; Li, Hui

    2015-05-30

    A cascaded model is proposed to establish the quantitative structure-activity relationship (QSAR) between the overall power conversion efficiency (PCE) and quantum chemical molecular descriptors of all-organic dye sensitizers. The cascaded model is a two-level network in which the outputs of the first level (JSC, VOC, and FF) are the inputs of the second level, and the ultimate end-point is the overall PCE of dye-sensitized solar cells (DSSCs). The model combines quantum chemical methods and machine learning methods, further including quantum chemical calculations, data division, feature selection, regression, and validation steps. To improve the efficiency of the model and reduce the redundancy and noise of the molecular descriptors, six feature selection methods (multiple linear regression, genetic algorithms, mean impact value, forward selection, backward elimination, and +n-m algorithm) are used with the support vector machine. The best established cascaded model predicts the PCE values of DSSCs with a MAE of 0.57 (%), which is about 10% of the mean value PCE (5.62%). The validation parameters according to the OECD principles are R(2) (0.75), Q(2) (0.77), and Qcv2 (0.76), which demonstrate the great goodness-of-fit, predictivity, and robustness of the model. Additionally, the applicability domain of the cascaded QSAR model is defined for further application. This study demonstrates that the established cascaded model is able to effectively predict the PCE for organic dye sensitizers with very low cost and relatively high accuracy, providing a useful tool for the design of dye sensitizers with high PCE.

  13. The Reading Proficiency Interview (RPI): A Rapid Response Test Development Model for Assessing Reading Proficiency on the ILR Scale

    ERIC Educational Resources Information Center

    Kennedy, Lauren; Stansfeld, Charles W.

    2010-01-01

    The Reading Proficiency Interview (RPI) is a new reading proficiency test format that was created in response to the US government's need to rapidly produce a cost effective and credible reading proficiency assessment format for small-population languages. The RPI was developed in response to a requirement by the National Language Service Corps…

  14. Comparison of the TSI Model 3306 Impactor Inlet with the Andersen Cascade Impactor: solution metered dose inhalers.

    PubMed

    Myrdal, Paul B; Stein, Stephen W; Mogalian, Erik; Hoye, William; Gupta, Abhishek

    2004-09-01

    The product performance of a series of solution Metered Dose Inhalers (MDIs) were evaluated using the TSI Model 3306 Impactor Inlet and the Andersen Cascade Impactor (ACI). The goal of the study was to test whether the fine particle and coarse particle depositions obtained using the Model 3306 were comparable to those results obtained by ACI testing. The analysis using the Model 3306 was performed as supplied by the manufacturer as well as with 20 cm and 40 cm vertical extensions that were inserted between the Model 3306 and the USP Inlet. Nine different solution formulations were evaluated. The drug concentrations ranged from 0.08 to 0.8% w/w and the ethanol cosolvent concentration varied between 5 and 20% w/w. In general, it was found that good correlations between the two instruments were obtained. However, for formulations containing 10-20% w/w ethanol it is shown that an extension fitted to the Model 3306 yielded an improved correlation to those obtained from the ACI.

  15. Computation of supersonic and low subsonic cascade flows using an explicit Navier-Stokes technique and the kappa-epsilon turbulence model

    NASA Technical Reports Server (NTRS)

    Kunz, R. F.; Lakshminarayana, B.

    1991-01-01

    A fully explicit two-dimensional flow solver, based on a four-stage Runge-Kutta scheme, was developed and utilized to predict two-dimensional viscous flow through turbomachinery cascades for which experimental data is available. The formulation is applied to the density averaged Navier-Stokes equations. Several features of the technique improve the ability of the code to predict high Reynolds number flows on highly stretched grids. These include a low Reynolds number compressible form of the k-epsilon turbulence model, anisotropic scaling of artificial dissipation terms and locally varying timestep evaluation based on hyperbolic and parabolic stability considerations. Comparisons between computation and experiment are presented for both a supersonic and a low-subsonic compressor cascade. These results indicate that the code is capable of predicting steady two-dimensional viscous cascade flows over a wide range of Mach numbers in reasonable computational times.

  16. Multifractality, imperfect scaling and hydrological properties of rainfall time series simulated by continuous universal multifractal and discrete random cascade models

    NASA Astrophysics Data System (ADS)

    Serinaldi, F.

    2010-12-01

    Discrete multiplicative random cascade (MRC) models were extensively studied and applied to disaggregate rainfall data, thanks to their formal simplicity and the small number of involved parameters. Focusing on temporal disaggregation, the rationale of these models is based on multiplying the value assumed by a physical attribute (e.g., rainfall intensity) at a given time scale L, by a suitable number b of random weights, to obtain b attribute values corresponding to statistically plausible observations at a smaller L/b time resolution. In the original formulation of the MRC models, the random weights were assumed to be independent and identically distributed. However, for several studies this hypothesis did not appear to be realistic for the observed rainfall series as the distribution of the weights was shown to depend on the space-time scale and rainfall intensity. Since these findings contrast with the scale invariance assumption behind the MRC models and impact on the applicability of these models, it is worth studying their nature. This study explores the possible presence of dependence of the parameters of two discrete MRC models on rainfall intensity and time scale, by analyzing point rainfall series with 5-min time resolution. Taking into account a discrete microcanonical (MC) model based on beta distribution and a discrete canonical beta-logstable (BLS), the analysis points out that the relations between the parameters and rainfall intensity across the time scales are detectable and can be modeled by a set of simple functions accounting for the parameter-rainfall intensity relationship, and another set describing the link between the parameters and the time scale. Therefore, MC and BLS models were modified to explicitly account for these relationships and compared with the continuous in scale universal multifractal (CUM) model, which is used as a physically based benchmark model. Monte Carlo simulations point out that the dependence of MC and BLS

  17. Beyond Market Models and Resistance: Organizations as a Middle Layer in the History of Reading

    ERIC Educational Resources Information Center

    Pawley, Christine

    2009-01-01

    Two theoretical models dominate discussion of research methods in the history of reading: "market" models such as Robert Darnton's communications circuit and "resistance" models such as those that draw on Michel de Certeau's concept of poaching. This article suggests that both make important contributions but also have limitations, especially when…

  18. Application of Three Cognitive Diagnosis Models to ESL Reading and Listening Assessments

    ERIC Educational Resources Information Center

    Lee, Yong-Won; Sawaki, Yasuyo

    2009-01-01

    The present study investigated the functioning of three psychometric models for cognitive diagnosis--the general diagnostic model, the fusion model, and latent class analysis--when applied to large-scale English as a second language listening and reading comprehension assessments. Data used in this study were scored item responses and incidence…

  19. Target fragments in collisions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion nuclei, and the cascade-evaporation model

    SciTech Connect

    Dudkin, V.E.; Kovalev, E.E.; Nefedov, N.A.; Antonchik, V.A.; Bogdanov, S.D.; Ostroumov, V.I.; Benton, E.V.; Crawford, H.J. ||

    1995-03-01

    Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).

  20. Interaction of Gold Nuclei with Photoemulsion Nuclei at Energies in the Range 100-1200 MeV per Nucleon and Cascade-Evaporation Model

    SciTech Connect

    Bogdanov, S.D.; Shablya, E.Ya.; Kosmach, V.F.; Vokal, S.; Plyuschev, V.A.

    2005-09-01

    The interaction of gold nuclei with photoemulsion nuclei at energies in the range 100-1200 MeV per nucleon was studied experimentally. A consistent comparison of the experimental data obtained in this way with the results of the calculations based on the cascade-evaporation model is performed.

  1. Modeling reading vocabulary learning in deaf children in bilingual education programs.

    PubMed

    Hermans, Daan; Knoors, Harry; Ormel, Ellen; Verhoeven, Ludo

    2008-01-01

    The acquisition of reading vocabulary is one of the major challenges for deaf children in bilingual education programs. Deaf children have to acquire a written lexicon that can effectively be used in reading. In this paper, we present a developmental model that describes reading vocabulary acquisition of deaf children in bilingual education programs. The model is inspired by Jiang's model of vocabulary development in a second language (N. Jiang, 2000, 2004a) and the hierarchical model of lexical representation and processing in bilinguals (J. F. Kroll & E. Stewart, 1988). We argue that lexical development in the written language often fossilizes and that many words deaf readers acquire will not reach the final stage of lexical development. We argue that this feature is consistent with many findings reported in the literature. Finally, we discuss the pedagogical implications of the model.

  2. Hadron cascades produced by electromagnetic cascades

    SciTech Connect

    Nelson, W.R.; Jenkins, T.M.; Ranft, J.

    1986-12-01

    A method for calculating high energy hadron cascades induced by multi-GeV electron and photon beams is described. Using the EGS4 computer program, high energy photons in the EM shower are allowed to interact hadronically according to the vector meson dominance (VMD) model, facilitated by a Monte Carlo version of the dual multistring fragmentation model which is used in the hadron cascade code FLUKA. The results of this calculation compare very favorably with experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets (i.e., yields in secondary particle beam lines). Electron beam induced hadron star density contours are also presented and are compared with those produced by proton beams. This FLUKA-EGS4 coupling technique could find use in the design of secondary beams, in the determination high energy hadron source terms for shielding purposes, and in the estimation of induced radioactivity in targets, collimators and beam dumps.

  3. Reconsidering the Simple View of Reading in an Intriguing Case of Equivalent Models: Commentary on Tunmer and Chapman (2012)

    ERIC Educational Resources Information Center

    Wagner, Richard K.; Herrera, Sarah K.; Spencer, Mercedes; Quinn, Jamie M.

    2015-01-01

    Recently, Tunmer and Chapman provided an alternative model of how decoding and listening comprehension affect reading comprehension that challenges the simple view of reading. They questioned the simple view's fundamental assumption that oral language comprehension and decoding make independent contributions to reading comprehension by arguing…

  4. A Case Study: The Implementation of a Problem-Solving Model with a Student with Reading Difficulties in Turkey

    ERIC Educational Resources Information Center

    Ozmen, E. Ruya; Doganay-Bilgi, Arzu

    2016-01-01

    The purpose of this case study was to improve the reading accuracy and reading comprehension of a 10-year-old fourth-grade female student with reading difficulties. For that purpose, the problem- solving model was implemented in four stages. These stages included problem identification, problem analysis, intervention, and evaluation. During the…

  5. A Longitudinal Study of Reading Comprehension Achievement from Grades 3 to 10: Investigating Models of Stability, Cumulative Growth, and Compensation

    ERIC Educational Resources Information Center

    Kwiatkowska-White, Bozena; Kirby, John R.; Lee, Elizabeth A.

    2016-01-01

    This longitudinal study of 78 Canadian English-speaking students examined the applicability of the stability, cumulative, and compensatory models in reading comprehension development. Archival government-mandated assessments of reading comprehension at Grades 3, 6, and 10, and the Canadian Test of Basic Skills measure of reading comprehension…

  6. X-ray-induced electron cascades in dielectrics modeled with XCASCADE code: effect of impact ionization cross sections

    NASA Astrophysics Data System (ADS)

    Medvedev, Nikita A.

    2015-05-01

    Characterization of a free-electron laser (FEL) pulse can be done with a pump-probe scheme, using an FEL pump and a visible light probe on an optically transparent solid-state target. With such experimental scheme, pulse duration can be monitored on a shot-to-shot basis. It relies on the changes in optical properties induced by the FEL excitation of electrons. Here we analyze effects of different cross sections used in the modeling of electron kinetics. XCASCADE, a Monte Carlo toolkit for modeling x-ray-induced electron cascades (N. Medvedev, Appl. Phys. B 118 (2015) 417), is used for this purpose. Two different cross sections are compared: atomic BEB model vs complex-dielectric function formalism that accounts for collective effects in solids. It is shown that for photon and electron energies above a few tens of eV, the both models coincide very closely. For lower energies in the VUV regime, the difference in the cross sections become more significant, nevertheless producing qualitatively similar electron kinetics and increase in the density of excited electrons.

  7. Disaggregating radar-derived rainfall measurements in East Azarbaijan, Iran, using a spatial random-cascade model

    NASA Astrophysics Data System (ADS)

    Fouladi Osgouei, Hojjatollah; Zarghami, Mahdi; Ashouri, Hamed

    2016-04-01

    The availability of spatial, high-resolution rainfall data is one of the most essential needs in the study of water resources. These data are extremely valuable in providing flood awareness for dense urban and industrial areas. The first part of this paper applies an optimization-based method to the calibration of radar data based on ground rainfall gauges. Then, the climatological Z-R relationship for the Sahand radar, located in the East Azarbaijan province of Iran, with the help of three adjacent rainfall stations, is obtained. The new climatological Z-R relationship with a power-law form shows acceptable statistical performance, making it suitable for radar-rainfall estimation by the Sahand radar outputs. The second part of the study develops a new heterogeneous random-cascade model for spatially disaggregating the rainfall data resulting from the power-law model. This model is applied to the radar-rainfall image data to disaggregate rainfall data with coverage area of 512 × 512 km2 to a resolution of 32 × 32 km2. Results show that the proposed model has a good ability to disaggregate rainfall data, which may lead to improvement in precipitation forecasting, and ultimately better water-resources management in this arid region, including Urmia Lake.

  8. Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle.

    PubMed

    de Oliveira, Samuel Conceição; de Castro, Heizir Ferreira; Visconti, Alexandre Eliseu Stourdze; Giudici, Reinaldo

    2015-03-01

    Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D 1 = D 2 = 0.27-0.95 h(-1)), constant recycle ratio (α = F R /F = 4.0) and a sugar concentration in the feed stream (S 0) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

  9. A universal approach to modeling visual word recognition and reading: Not only possible, but also inevitable

    PubMed Central

    Frost, Ram

    2013-01-01

    I have argued that orthographic processing cannot be understood and modeled without considering the manner in which orthographic structure represents phonological, semantic and morphological information in a given writing system. A reading theory, therefore, must be a theory of the interaction of the reader with his/her linguistic environment. This outlines a novel approach to studying and modeling visual word recognition, an approach that focuses on the common cognitive principles involved in processing printed words across different writing systems. These claims were challenged by several commentaries that contested the merits of my general theoretical agenda, the relevance of the evolution of writing systems, and the plausibility of finding commonalities in reading across orthographies. Other commentaries extended the scope of the debate by bringing into the discussion additional perspectives. My response addresses all these issues. By considering the constraints of neurobiology on modeling reading, developmental data, and a large scope of cross-linguistic evidence, I argue that front-end implementations of orthographic processing that do not stem from a comprehensive theory of the complex information conveyed by writing systems do not present a viable approach for understanding reading. The common principles by which writing systems have evolved to represent orthographic, phonological and semantic information in a language reveal the critical distributional characteristics of orthographic structure that govern reading behavior. Models of reading should thus be learning models, primarily constrained by cross-linguistic developmental evidence that describes how the statistical properties of writing systems shape the characteristics of orthographic processing. When this approach is adopted a universal model of reading is possible. PMID:23251930

  10. Modeling the Relationships Among Reading Instruction, Motivation, Engagement, and Achievement for Adolescents

    PubMed Central

    Guthrie, John T.; Klauda, Susan Lutz; Ho, Amy N.

    2015-01-01

    This study modeled the interrelationships of reading instruction, motivation, engagement, and achievement in two contexts, employing data from 1,159 seventh graders. In the traditional reading/language arts (R/LA) context, all students participated in traditional R/LA instruction. In the intervention R/LA context, 854 students from the full sample received Concept-Oriented Reading Instruction (CORI) while the remainder continued to receive traditional R/LA. CORI emphasizes support for reading motivation, reading engagement, and cognitive strategies for reading informational text. Seven motivation constructs were included: four motivations that are usually positively associated with achievement (intrinsic motivation, self-efficacy, valuing, and prosocial goals) and three motivations that are usually negatively associated with achievement (perceived difficulty, devaluing, and antisocial goals). Reading engagement was also represented by positive and negative constructs, namely dedication to and avoidance of reading. Gender, ethnicity, and income were statistically controlled in all analyses. In the traditional R/LA context, a total network model prevailed, in which motivation was associated with achievement both directly and indirectly through engagement. In contrast, in the intervention R/LA context, a dual-effects model prevailed, in which engagement and achievement were separate outcomes of instruction and motivation. The intervention R/LA context analyses revealed that CORI was associated with positive changes in motivation, engagement, and achievement relative to traditional R/LA instruction. The discussion explains why there were different relations in the two instructional contexts and demonstrates the importance of simultaneously examining both positive (affirming) and negative (undermining) forms of motivation and engagement. PMID:26412903

  11. Stochastic background of atmospheric cascades

    SciTech Connect

    Wilk, G. ); Wlodarczyk, Z. )

    1993-06-15

    Fluctuations in the atmospheric cascades developing during the propagation of very high energy cosmic rays through the atmosphere are investigated using stochastic branching model of pure birth process with immigration. In particular, we show that the multiplicity distributions of secondaries emerging from gamma families are much narrower than those resulting from hadronic families. We argue that the strong intermittent like behaviour found recently in atmospheric families results from the fluctuations in the cascades themselves and are insensitive to the details of elementary interactions.

  12. Cascading gravity is ghost free

    SciTech Connect

    Rham, Claudia de; Khoury, Justin; Tolley, Andrew J.

    2010-06-15

    We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.

  13. Recent Developments of the Liège Intranuclear Cascade Model in View of its Use into High-energy Transport Codes

    NASA Astrophysics Data System (ADS)

    Leray, S.; Boudard, A.; Braunn, B.; Cugnon, J.; David, J. C.; Leprince, A.; Mancusi, D.

    2014-04-01

    Recent extensions of the Liège Intranuclear Cascade model, INCL, at energies below 100 MeV and for light-ion (up to oxygen) induced reactions are reported. Comparisons with relevant experimental data are shown. The model has been implemented into several high-energy transport codes allowing simulations in a wide domain of applications. Examples of simulations performed for spallation targets with the model implemented into MCNPX and in the domain of medical applications with GEANT4 are presented.

  14. Haplotype inference from short sequence reads using a population genealogical history model.

    PubMed

    Zhang, Jin; Wu, Yufeng

    2011-01-01

    High-throughput sequencing is currently a major transforming technology in biology. In this paper, we study a population genomics problem motivated by the newly available short reads data from high-throughput sequencing. In this problem, we are given short reads collected from individuals in a population. The objective is to infer haplotypes with the given reads. We first formulate the computational problem of haplotype inference with short reads. Based on a simple probabilistic model on short reads, we present a new approach of inferring haplotypes directly from given reads (i.e. without first calling genotypes). Our method is finding the most likely haplotypes whose local genealogical history can be approximately modeled as a perfect phylogeny. We show that the optimal haplotypes under this objective can be found for many data using integer linear programming for modest sized data when there is no recombination. We then develop a related heuristic method which can work with larger data, and also allows recombination. Simulation shows that the performance of our method is competitive against alternative approaches.

  15. A Dual Coding Theoretical Model of Decoding in Reading: Subsuming the LaBerge and Samuels Model

    ERIC Educational Resources Information Center

    Sadoski, Mark; McTigue, Erin M.; Paivio, Allan

    2012-01-01

    In this article we present a detailed Dual Coding Theory (DCT) model of decoding. The DCT model reinterprets and subsumes The LaBerge and Samuels (1974) model of the reading process which has served well to account for decoding behaviors and the processes that underlie them. However, the LaBerge and Samuels model has had little to say about…

  16. Random cascade model in the limit of infinite integral scale as the exponential of a nonstationary 1/f noise: Application to volatility fluctuations in stock markets

    NASA Astrophysics Data System (ADS)

    Muzy, Jean-François; Baïle, Rachel; Bacry, Emmanuel

    2013-04-01

    In this paper we propose a new model for volatility fluctuations in financial time series. This model relies on a nonstationary Gaussian process that exhibits aging behavior. It turns out that its properties, over any finite time interval, are very close to continuous cascade models. These latter models are indeed well known to reproduce faithfully the main stylized facts of financial time series. However, it involves a large-scale parameter (the so-called “integral scale” where the cascade is initiated) that is hard to interpret in finance. Moreover, the empirical value of the integral scale is in general deeply correlated to the overall length of the sample. This feature is precisely predicted by our model, which, as illustrated by various examples from daily stock index data, quantitatively reproduces the empirical observations.

  17. The Stress-Induced Atf3-Gelsolin Cascade Underlies Dendritic Spine Deficits in Neuronal Models of Tuberous Sclerosis Complex

    PubMed Central

    Nie, Duyu; Chen, Zehua; Ebrahimi-Fakhari, Darius; Di Nardo, Alessia; Julich, Kristina; Robson, Victoria K.; Cheng, Yung-Chih; Woolf, Clifford J.; Heiman, Myriam

    2015-01-01

    Hyperactivation of the mechanistic target of rapamycin (mTOR) kinase, as a result of loss-of-function mutations in tuberous sclerosis complex 1 (TSC1) or TSC2 genes, causes protein synthesis dysregulation, increased cell size, and aberrant neuronal connectivity. Dysregulated synthesis of synaptic proteins has been implicated in the pathophysiology of autism spectrum disorder (ASD) associated with TSC and fragile X syndrome. However, cell type-specific translational profiles in these disease models remain to be investigated. Here, we used high-fidelity and unbiased Translating Ribosome Affinity Purification (TRAP) methodology to purify ribosome-associated mRNAs and identified translational alterations in a rat neuronal culture model of TSC. We find that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed. Importantly, transcripts for the activating transcription factor-3 (Atf3) and mitochondrial uncoupling protein-2 (Ucp2) are highly induced in Tsc2-deficient neurons, as well as in a neuron-specific Tsc1 conditional knock-out mouse model, and show differential responses to the mTOR inhibitor rapamycin. Gelsolin, a known target of Atf3 transcriptional activity, is also upregulated. shRNA-mediated block of Atf3 induction suppresses expression of gelsolin, an actin-severing protein, and rescues spine deficits found in Tsc2-deficient neurons. Together, our data demonstrate that a cell-autonomous program consisting of a stress-induced Atf3-gelsolin cascade affects the change in dendritic spine morphology following mTOR hyperactivation. This previously unidentified molecular cascade could be a therapeutic target for treating mTORopathies. SIGNIFICANCE STATEMENT Tuberous sclerosis complex (TSC) is a genetic disease associated with epilepsy and autism. Dysregulated protein synthesis has been implicated as a cause of this disease. However, cell type-specific translational profiles that are aberrant in this

  18. New potentialities of the Liège intranuclear cascade model for reactions induced by nucleons and light charged particles

    NASA Astrophysics Data System (ADS)

    Boudard, A.; Cugnon, J.; David, J.-C.; Leray, S.; Mancusi, D.

    2013-01-01

    The new version (incl4.6) of the Liège intranuclear cascade (INC) model for the description of spallation reactions is presented in detail. Compared to the standard version (incl4.2), it incorporates several new features, the most important of which are: (i) the inclusion of cluster production through a dynamical phase space coalescence model, (ii) the Coulomb deflection for entering and outgoing charged particles, (iii) the improvement of the treatment of Pauli blocking and of soft collisions, (iv) the introduction of experimental threshold values for the emission of particles, (v) the improvement of pion dynamics, (vi) a detailed procedure for the treatment of light-cluster-induced reactions taking care of the effects of binding energy of the nucleons inside the incident cluster and of the possible fusion reaction at low energy. Performances of the new model concerning nucleon-induced reactions are illustrated by a comparison with experimental data covering total reaction cross sections, neutron, proton, pion, and composite double-differential cross-sections, neutron multiplicities, residue mass and charge distributions, and residue recoil velocity distributions. Whenever necessary, the incl4.6 model is coupled to the ABLA07 de-excitation model and the respective merits of the two models are then tentatively disentangled. Good agreement is generally obtained in the 200 MeV to 2 GeV range. Below 200 MeV and down to a few tens of MeV, the total reaction cross section is well reproduced and differential cross sections are reasonably well described. The model is also tested for light-ion induced reactions at low energy, below 100 MeV incident energy per nucleon. Beyond presenting the update of the incl4.2 model, attention has been paid to applications of the new model to three topics for which some particular aspects are discussed for the first time. The first topic is the production of clusters heavier than alpha particle. It is shown that the energy spectra of

  19. The Effect of Flipped Model of Instruction on EFL Learners' Reading Comprehension: Learners' Attitudes in Focus

    ERIC Educational Resources Information Center

    Karimi, Mehrnoosh; Hamzavi, Raouf

    2017-01-01

    The present study aimed at investigating the effect of flipped model of instruction on EFL learners' reading comprehension ability. Moreover, this study aimed at identifying EFL students' attitudes toward flipped model of instruction. To this end, 60 EFL learners studying at an accredited private language institute in Isfahan were first…

  20. Developmental Relations between Vocabulary Knowledge and Reading Comprehension: A Latent Change Score Modeling Study

    ERIC Educational Resources Information Center

    Quinn, Jamie M.; Wagner, Richard K.; Petscher, Yaacov; Lopez, Danielle

    2015-01-01

    The present study followed a sample of first-grade (N = 316, M[subscript age] = 7.05 at first test) through fourth-grade students to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and…

  1. Applying Unidimensional and Multidimensional Item Response Theory Models in Testlet-Based Reading Assessment

    ERIC Educational Resources Information Center

    Min, Shangchao; He, Lianzhen

    2014-01-01

    This study examined the relative effectiveness of the multidimensional bi-factor model and multidimensional testlet response theory (TRT) model in accommodating local dependence in testlet-based reading assessment with both dichotomously and polytomously scored items. The data used were 14,089 test-takers' item-level responses to the testlet-based…

  2. Cascades on clique-based graphs.

    PubMed

    Hackett, Adam; Gleeson, James P

    2013-06-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly clustered random graphs introduced by Gleeson [J. P. Gleeson, Phys. Rev. E 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  3. Understanding Dysregulated Behaviors and Compulsions: An Extension of the Emotional Cascade Model and the Mediating Role of Intrusive Thoughts

    PubMed Central

    Jungmann, Stefanie M.; Vollmer, Noelle; Selby, Edward A.; Witthöft, Michael

    2016-01-01

    Objective: The Emotional Cascade Model (ECM) by Selby et al. (2008) proposes that people often engage in dysregulated behaviors to end extreme, aversive emotional states triggered by a self-perpetuating vicious cycle of (excessive) rumination, negative affect, and attempts to suppress negative thoughts. Method: Besides replicating the ECM, we introduced intrusions as a mediator between rumination and behavioral dysregulation and tested this extended ECM for compulsions as part of obsessive–compulsive disorders. A structural equation modeling approach was used to test this in a sample of N = 414, randomly recruited from the general population. Results: Intrusions were found to fully mediate the effect of rumination on a broad array of dysregulated behaviors and compulsions. This mediation endured when controlling for symptoms of depression. Conclusion: These findings support the idea that rumination fuels intrusions, which in turn foster dysregulated behaviors. Therefore, addressing rumination as well as intrusions may improve psychotherapeutic interventions for mental disorders characterized by dysregulated behaviors and/or extreme aversive emotional states. PMID:27445948

  4. A SPICE model for Si microstrip detectors and read-out electronics

    SciTech Connect

    Bacchetta, N.; Candelori, A.; Bisello, D. |; Calgarotto, C.; Paccagnella, A. |

    1996-06-01

    The authors have developed a SPICE model of silicon microstrip detector and its read-out electronics. The SPICE model of an AC-coupled single-sided polysilicon-biased silicon microstrip detector has been implemented by using a RC network containing up to 19 strips. The main parameters of this model have been determined by direct comparison with DC and AC measurements. The simulated interstrip and coupling impedance and phase angle are in good agreement with experimental results, up to a frequency of 1 MHz. The authors have used the PreShape 32 as the read-out chip for both the simulation and the measurements. It consists of a charge sensitive preamplifier followed by a shaper and a buffer. The SPICE parameters have been adjusted to fit the experimental results obtained for the configuration where every strip is connected to the read-out electronics and kept the same for the different read-out configurations they have considered. By adding 2 further capacitances simulating the parasitic contributions between the read-out channels of the PS32 chip, a satisfactory matching between the experimental data and the simulated curves has been reached on both rising and trailing edges of the signal. Such agreement deteriorates only for strips far from the strip where the signal has been applied.

  5. Neural Mechanisms of Saccade Target Selection: Gated Accumulator Model of Visual-Motor Cascade

    PubMed Central

    Schall, Jeffrey D.; Purcell, Braden A.; Heitz, Richard P.; Logan, Gordon D.; Palmeri, Thomas J.

    2011-01-01

    We review a new computational model developed to understand how evidence about stimulus salience in visual search is translated into a saccade command. The model uses the activity of visually responsive neurons in the frontal eye field as evidence for stimulus salience that is accumulated in a network of stochastic accumulators to produce accurate and timely saccades. We discovered that only when the input to the accumulation process is gated could the model account for the variability in search performance and predict the dynamics of movement neuron discharge rates. This union of cognitive modeling and neurophysiology indicates how the visual-motor transformation can occur and provides a concrete mapping between neuron function and specific cognitive processes. PMID:21645095

  6. Tetrahedral Models of Learning: Application to College Reading.

    ERIC Educational Resources Information Center

    Nist, Sherrie L.

    J. D. Bransford's tetrahedral model of learning considers four variables: (1) learning activities, (2) characteristics of the learner, (3) criterial tasks, and (4) the nature of the materials. Bransford's model provides a research-based theoretical framework that can be used to teach, model, and have students apply a variety of study strategies to…

  7. The Paleoclimate Uncertainty Cascade: Tracking Proxy Errors Via Proxy System Models.

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Dee, S. G.; Evans, M. N.; Adkins, J. F.

    2014-12-01

    Paleoclimatic observations are, by nature, imperfect recorders of climate variables. Empirical approaches to their calibration are challenged by the presence of multiple sources of uncertainty, which may confound the interpretation of signals and the identifiability of the noise. In this talk, I will demonstrate the utility of proxy system models (PSMs, Evans et al, 2013, 10.1016/j.quascirev.2013.05.024) to quantify the impact of all known sources of uncertainty. PSMs explicitly encode the mechanistic knowledge of the physical, chemical, biological and geological processes from which paleoclimatic observations arise. PSMs may be divided into sensor, archive and observation components, all of which may conspire to obscure climate signals in actual paleo-observations. As an example, we couple a PSM for the δ18O of speleothem calcite to an isotope-enabled climate model (Dee et al, submitted) to analyze the potential of this measurement as a proxy for precipitation amount. A simple soil/karst model (Partin et al, 2013, 10.1130/G34718.1) is used as sensor model, while a hiatus-permitting chronological model (Haslett & Parnell, 2008, 10.1111/j.1467-9876.2008.00623.x) is used as part of the observation model. This subdivision allows us to explicitly model the transformation from precipitation amount to speleothem calcite δ18O as a multi-stage process via a physical and chemical sensor model, and a stochastic archive model. By illustrating the PSM's behavior within the context of the climate simulations, we show how estimates of climate variability may be affected by each submodel's transformation of the signal. By specifying idealized climate signals(periodic vs. episodic, slow vs. fast) to the PSM, we investigate how frequency and amplitude patterns are modulated by sensor and archive submodels. To the extent that the PSM and the climate models are representative of real world processes, then the results may help us more accurately interpret existing paleodata

  8. A neurally plausible parallel distributed processing model of event-related potential word reading data.

    PubMed

    Laszlo, Sarah; Plaut, David C

    2012-03-01

    The Parallel Distributed Processing (PDP) framework has significant potential for producing models of cognitive tasks that approximate how the brain performs the same tasks. To date, however, there has been relatively little contact between PDP modeling and data from cognitive neuroscience. In an attempt to advance the relationship between explicit, computational models and physiological data collected during the performance of cognitive tasks, we developed a PDP model of visual word recognition which simulates key results from the ERP reading literature, while simultaneously being able to successfully perform lexical decision-a benchmark task for reading models. Simulations reveal that the model's success depends on the implementation of several neurally plausible features in its architecture which are sufficiently domain-general to be relevant to cognitive modeling more generally.

  9. The Relationship between Reading Attitude, Metacognitive Awareness of Reading Strategies, Personality and Self-Regulation: A Study of Modeling

    ERIC Educational Resources Information Center

    Turkyilmaz, Mustafa

    2015-01-01

    This study aimed at investigating the relationship between reading attitude, personality, self-regulation and metacognitive awareness of reading strategies of secondary school students. In order to carry out the aim four scales were used to 419 high school students in Kirsehir province in Turkey. It was used Lisrel 8.80 and SPSS software to…

  10. Development of a Higher Fidelity Model for the Cascade Distillation Subsystem (CDS)

    NASA Technical Reports Server (NTRS)

    Perry, Bruce; Anderson, Molly

    2014-01-01

    Significant improvements have been made to the ACM model of the CDS, enabling accurate predictions of dynamic operations with fewer assumptions. The model has been utilized to predict how CDS performance would be impacted by changing operating parameters, revealing performance trade-offs and possibilities for improvement. CDS efficiency is driven by the THP coefficient of performance, which in turn is dependent on heat transfer within the system. Based on the remaining limitations of the simulation, priorities for further model development include: center dot Relaxing the assumption of total condensation center dot Incorporating dynamic simulation capability for the buildup of dissolved inert gasses in condensers center dot Examining CDS operation with more complex feeds center dot Extending heat transfer analysis to all surfaces

  11. Modeling and hazard mapping of complex cascading mass movement processes: the case of glacier lake 513, Carhuaz, Peru

    NASA Astrophysics Data System (ADS)

    Schneider, Demian; Huggel, Christian; García, Javier; Ludeña, Sebastian; Cochachin, Alejo

    2013-04-01

    that complex cascades of mass movement processes can realistically be modeled using different models and model parameters. The method to semi-automatically produce hazard maps is promising and should be applied in other case studies. Verification of model based results in the field remains an important requirement. Results from this study are important for the GLOF early warning system that is currently in an implementation phase, and for risk reduction efforts in general.

  12. Rupture cascades in a discrete element model of a porous sedimentary rock.

    PubMed

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G

    2014-02-14

    We investigate the scaling properties of the sources of crackling noise in a fully dynamic numerical model of sedimentary rocks subject to uniaxial compression. The model is initiated by filling a cylindrical container with randomly sized spherical particles that are then connected by breakable beams. Loading at a constant strain rate the cohesive elements fail, and the resulting stress transfer produces sudden bursts of correlated failures, directly analogous to the sources of acoustic emissions in real experiments. The source size, energy, and duration can all be quantified for an individual event, and the population can be analyzed for its scaling properties, including the distribution of waiting times between consecutive events. Despite the nonstationary loading, the results are all characterized by power-law distributions over a broad range of scales in agreement with experiments. As failure is approached, temporal correlation of events emerges accompanied by spatial clustering.

  13. Rupture Cascades in a Discrete Element Model of a Porous Sedimentary Rock

    NASA Astrophysics Data System (ADS)

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G.

    2014-02-01

    We investigate the scaling properties of the sources of crackling noise in a fully dynamic numerical model of sedimentary rocks subject to uniaxial compression. The model is initiated by filling a cylindrical container with randomly sized spherical particles that are then connected by breakable beams. Loading at a constant strain rate the cohesive elements fail, and the resulting stress transfer produces sudden bursts of correlated failures, directly analogous to the sources of acoustic emissions in real experiments. The source size, energy, and duration can all be quantified for an individual event, and the population can be analyzed for its scaling properties, including the distribution of waiting times between consecutive events. Despite the nonstationary loading, the results are all characterized by power-law distributions over a broad range of scales in agreement with experiments. As failure is approached, temporal correlation of events emerges accompanied by spatial clustering.

  14. Modelling cascading and erosional processes for glacial lake outburst floods in the Quillcay catchment, Huaraz, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Baer, Patrick; Huggel, Christian; Frey, Holger; Chisolm, Rachel; McKinney, Daene; McArdell, Brian; Portocarrero, Cesar; Cochachin, Alejo

    2016-04-01

    Huaraz as the largest city in Cordillera Blanca has faced a major disaster in 1941, when an outburst flood from Lake Palcacocha killed several thousand people and caused widespread destruction. Recent studies on glacial lake outburst flood (GLOF) modelling and early warning systems focussed on Lake Palcacocha which has regrown after the 1941 event, from a volume of half a million m3 in 1974 to a total volume of more than 17 million m3 today. However, little research has been conducted so far concerning the situation of other lakes in the Quillcay catchment, namely Lake Tullparaju (12 mill. m3) and Cuchillacocha (2.5 mill. m3), which both also pose a threat to the city of Huaraz. In this study, we modelled the cascading processes at Lake Tullparaju and Lake Cuchillacocha including rock/ice avalanches, flood wave propagation in the lake and the resulting outburst flood and debris flows. We used the 2D model RAMMS to simulate ice avalanches. Model output was used as input for analytical 2D and 3D calculations of impact waves in the lakes that allowed us to estimate dam overtopping wave height. Since the dimension of the hanging glaciers above all three lakes is comparable, the scenarios in this study have been defined similar to the previous study at Lake Palcacocha. The flow propagation model included sediment entrainment in the steeper parts of the catchment, adding up to 50% to the initial flow volume. The results for total travel time as well as for inundated areas and flow depth and velocity in the city of Huaraz are comparable to the previous studies at Lake Palcacocha. This underlines the importance of considering also these lakes within an integral hazard analysis for the city of Huaraz. A main challenge for modelling GLOFs in the Quillcay catchment using RAMMS is the long runout distance of over 22 km combined with the very low slope gradient of the river. Further studies could improve the process understanding and could focus on more detailed investigations

  15. Autoregressive cascades on random networks

    NASA Astrophysics Data System (ADS)

    Iyer, Srikanth K.; Vaze, Rahul; Narasimha, Dheeraj

    2016-04-01

    A network cascade model that captures many real-life correlated node failures in large networks via load redistribution is studied. The considered model is well suited for networks where physical quantities are transmitted, e.g., studying large scale outages in electrical power grids, gridlocks in road networks, and connectivity breakdown in communication networks, etc. For this model, a phase transition is established, i.e., existence of critical thresholds above or below which a small number of node failures lead to a global cascade of network failures or not. Theoretical bounds are obtained for the phase transition on the critical capacity parameter that determines the threshold above and below which cascade appears or disappears, respectively, that are shown to closely follow numerical simulation results.

  16. Using Hierarchical Linear Modelling to Examine Factors Predicting English Language Students' Reading Achievement

    ERIC Educational Resources Information Center

    Fung, Karen; ElAtia, Samira

    2015-01-01

    Using Hierarchical Linear Modelling (HLM), this study aimed to identify factors such as ESL/ELL/EAL status that would predict students' reading performance in an English language arts exam taken across Canada. Using data from the 2007 administration of the Pan-Canadian Assessment Program (PCAP) along with the accompanying surveys for students and…

  17. Conceptual Model for Nonintellectual Behavior and Its Relationship to Early Reading Achievement

    ERIC Educational Resources Information Center

    Lambert, Nadine M.; Nicoll, Richard C.

    1977-01-01

    A model relating nonintellectual behavior to first and second grade reading performance is supported. The three dimensions include: (1) behaviors reflecting adaptation to school; (2) individual differences in emotional states; and (3) individual differences in interpersonal behavior. These affective behaviors are measured using Lambert's Pupil…

  18. Vocabulary and Grammar Knowledge in Second Language Reading Comprehension: A Structural Equation Modeling Study

    ERIC Educational Resources Information Center

    Zhang, Dongbo

    2012-01-01

    Using structural equation modeling analysis, this study examined the contribution of vocabulary and grammatical knowledge to second language reading comprehension among 190 advanced Chinese English as a foreign language learners. Vocabulary knowledge was measured in both breadth (Vocabulary Levels Test) and depth (Word Associates Test);…

  19. Exploring Reading Comprehension Skill Relationships through the G-DINA Model

    ERIC Educational Resources Information Center

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    By analysing the test data of 1029 British secondary school students' performance on 20 Programme for International Student Assessment English reading items through the generalised deterministic input, noisy "and" gate (G-DINA) model, the study conducted two investigations on exploring the relationships among the five reading…

  20. Longitudinal Models of Developmental Dynamics Between Reading and Cognition from Childhood to Adolescence

    ERIC Educational Resources Information Center

    Ferrer, Emilio; McArdle, John J.; Shaywitz, Bennett A.; Holahan, John M.; Marchione, Karen; Shaywitz, Sally E.

    2007-01-01

    The authors applied linear dynamic models to longitudinal data to examine the dynamics of reading and cognition from 1st to 12th grade. They used longitudinal data (N=445) from the Connecticut Longitudinal Study (S. E. Shaywitz, B. A. Shaywitz, J. M. Fletcher, & M. D. Escobar, 1990) to map the dynamic interrelations of various scales of the…

  1. An Interdisciplinary Inservice Model for Teaching Reading in the Content Areas: Grades 7-9.

    ERIC Educational Resources Information Center

    Granite School District, Salt Lake City, UT.

    The model outlined in this document describes the development of an integrated approach to teaching content reading skills to teachers. Methods and materials applicable to texts and media currently used in classrooms were produced by inservice teachers of science, math, and social studies at a Salt Lake City junior high school. This document…

  2. Reading direction causes spatial biases in mental model construction in language understanding

    PubMed Central

    Román, Antonio; Flumini, Andrea; Lizano, Pilar; Escobar, Marysol; Santiago, Julio

    2015-01-01

    Correlational evidence suggests that the experience of reading and writing in a certain direction is able to induce spatial biases at both low-level perceptuo-motor skills and high-level conceptual representations. However, in order to support a causal relationship, experimental evidence is required. In this study, we asked whether the direction of the script is a sufficiente cause of spatial biases in the mental models that understanders build when listening to language. In order to establish causality, we manipulated the experience of reading a script with different directionalities. Spanish monolinguals read either normal (left-to-right), mirror reversed (right-to-left), rotated downward (up-down), or rotated upward (down-up) texts, and then drew the contents of auditory descriptions such as “the square is between the cross and the triangle”. The directionality of the drawings showed that a brief reading experience is enough to cause congruent and very specific spatial biases in mental model construction. However, there were also clear limits to this flexibility: there was a strong overall preference to arrange the models along the horizontal dimension. Spatial preferences when building mental models from language are the results of both short-term and long-term biases. PMID:26667996

  3. Encoder: A Connectionist Model of How Learning to Visually Encode Fixated Text Images Improves Reading Fluency

    ERIC Educational Resources Information Center

    Martin, Gale L.

    2004-01-01

    This article proposes that visual encoding learning improves reading fluency by widening the span over which letters are recognized from a fixated text image so that fewer fixations are needed to cover a text line. Encoder is a connectionist model that learns to convert images like the fixated text images human readers encode into the…

  4. Concentrated Language Encounter Instruction Model III in Reading and Creative Writing Abilities

    ERIC Educational Resources Information Center

    Promnont, Piyapong; Rattanavich, Saowalak

    2015-01-01

    The research is aimed to study the development of eleventh grade students' reading, creative writing abilities, satisfaction taught through the concentrated language encounter instruction method, CLE model III. One experimental group time series design was used, and the data was analyzed by MANOVA with repeated measures, t-test for one-group…

  5. Using Peer Collaboration to Support Online Reading, Writing, and Communication: An Empowerment Model for Struggling Readers

    ERIC Educational Resources Information Center

    Henry, Laurie A.; Castek, Jill; O'Byrne, W. Ian; Zawilinski, Lisa

    2012-01-01

    This comparative case study investigated the implementation of an empowerment model for struggling readers that utilized the Internet as a context for reading, writing, and communicating in 3 different classroom contexts. Through student-centered techniques, such as flexible grouping and peer teaching, we designed Internet Reciprocal Teaching to…

  6. Is the Medical Model Making Our Children Sick--of Reading?

    ERIC Educational Resources Information Center

    Heller, Marvin; Hornby, Joyce

    The skills-based method of remedial reading instruction is based on a medical model, in that it focuses instructional efforts solely on "curing" what is "wrong" with a reader. Such attention to students' shortcomings and the labeling of their lack of instant success as a problem causes healthy learners to begin to doubt their own abilities, often…

  7. Testing the Multiple in the Multiple Read-Out Model of Visual Word Recognition

    ERIC Educational Resources Information Center

    De Moor, Wendy; Verguts, Tom; Brysbaert, Marc

    2005-01-01

    This study provided a test of the multiple criteria concept used for lexical decision, as implemented in J. Grainger and A. M. Jacobs's (1996) multiple read-out model. This account predicts more inhibition (or less facilitation) from a masked neighbor when accuracy is stressed more but more facilitation (or less inhibition) when the speed of…

  8. Equating Reading Tests With the Rasch Model. Volume II, Technical Reference Tables.

    ERIC Educational Resources Information Center

    Rentz, R. Robert; Bashaw, W. L.

    This volume contains tables of item analysis results obtained by following procedures associated with the Rasch Model for those reading tests used in the Anchor Test Study. Appendix I gives the test names and their corresponding analysis code numbers. Section I (Basic Item Analyses) presents data for the item analysis of each test in a two part…

  9. A Model of Motivation for Extensive Reading in Japanese as a Foreign Language

    ERIC Educational Resources Information Center

    de Burgh-Hirabe, Ryoko; Feryok, Ann

    2013-01-01

    Numerous studies have reported that extensive reading (ER) has a positive influence on affect. Recent studies suggest that motivation for ER changes. This is in line with recent developments in second language (L2) motivation research that have highlighted the complex and dynamic nature of L2 motivation. This study presents a model of complex and…

  10. Fitting Item Response Models to the Maryland Functional Reading Test Results.

    ERIC Educational Resources Information Center

    Hambleton, Ronald K.; And Others

    The potential of item response theory (IRT) for solving a number of testing problems in the Maryland Functional Reading Program would appear to be substantial in view of the many other promising applications of the theory. But, it is well-known that the advantages derived from an IRT model cannot be achieved when the fit between an item response…

  11. Vers un modele d'intervention precoce en lecture en actualisation linguistique (Towards a Model of Early Intervention in Reading Readiness).

    ERIC Educational Resources Information Center

    Berger, Marie Josee

    1999-01-01

    Argues that in Ontario's French-medium schools, reading is often a challenge, particularly for those in readiness classes who speak little or no French. A model for early intervention in reading is recommended, combining reading and writing to address the linguistic challenges of students in a minority-language community. (Author/MSE)

  12. Serial processing in reading aloud: no challenge for a parallel model.

    PubMed

    Zorzi, M

    2000-04-01

    K. Rastle and M. Coltheart (1999) challenged parallel models of reading by showing that the cost of irregularity in low-frequency exception words was modulated by the position of the irregularity in the word. This position-of-irregularity effect was taken as strong evidence of serial processing in reading. This article refutes Rastle and Coltheart's theoretical conclusions in 3 ways: First, a parallel model, the connectionist dual process model (M. Zorzi, G. Houghton, & B. Butterworth, 1998b), produces a position-of-irregularity effect. Second, the supposed serial effect can be reduced to a position-specific grapheme-phoneme consistency effect. Third, the position-of-irregularity effect vanishes when the experimental data are reanalyzed using grapheme-phoneme consistency as the covariate. This demonstration has broader implications for studies aiming at adjudicating between models: Strong inferences should be avoided until the computational models are actually tested.

  13. Precursors of Adolescent Substance Use from Early Childhood and Early Adolescence: Testing a Developmental Cascade Model

    PubMed Central

    Sitnick, Stephanie; Shaw, Daniel S.; Hyde, Luke

    2013-01-01

    This study examined developmentally-salient risk and protective factors of adolescent substance use assessed during early childhood and early adolescence using a sample of 310 low-income boys. Child problem behavior and proximal family risk and protective factors (i.e., parenting, maternal depression) during early childhood, as well as child and family factors and peer deviant behavior during adolescence were explored as potential precursors to later substance use during adolescence using structural equation modeling. Results revealed that early childhood risk and protective factors (i.e., child externalizing problems, mothers’ depressive symptomatology, and nurturant parenting) were indirectly related to substance use at the age of 17 via risk and protective factors during early and middle adolescence (i.e., parental knowledge and externalizing problems). The implications of these findings for early prevention and intervention are discussed. PMID:24029248

  14. The equal load-sharing model of cascade failures in power grids

    NASA Astrophysics Data System (ADS)

    Scala, Antonio; De Sanctis Lucentini, Pier Giorgio

    2016-11-01

    Electric power-systems are one of the most important critical infrastructures. In recent years, they have been exposed to extreme stress due to the increasing power demand, the introduction of distributed renewable energy sources, and the development of extensive interconnections. We investigate the phenomenon of abrupt breakdown of an electric power-system under two scenarios: load growth (mimicking the ever-increasing customer demand) and power fluctuations (mimicking the effects of renewable sources). Our results indicate that increasing the system size causes breakdowns to become more abrupt; in fact, mapping the system to a solvable statistical-physics model indicates the occurrence of a first order transition in the large size limit. Such an enhancement for the systemic risk failures (black-outs) with increasing network size is an effect that should be considered in the current projects aiming to integrate national power-grids into "super-grids".

  15. Precursors of adolescent substance use from early childhood and early adolescence: testing a developmental cascade model.

    PubMed

    Sitnick, Stephanie L; Shaw, Daniel S; Hyde, Luke W

    2014-02-01

    This study examined developmentally salient risk and protective factors of adolescent substance use assessed during early childhood and early adolescence using a sample of 310 low-income boys. Child problem behavior and proximal family risk and protective factors (i.e., parenting and maternal depression) during early childhood, as well as child and family factors and peer deviant behavior during adolescence, were explored as potential precursors to later substance use during adolescence using structural equation modeling. Results revealed that early childhood risk and protective factors (i.e., child externalizing problems, mothers' depressive symptomatology, and nurturant parenting) were indirectly related to substance use at the age of 17 via risk and protective factors during early and middle adolescence (i.e., parental knowledge and externalizing problems). The implications of these findings for early prevention and intervention are discussed.

  16. Applying a Multiple Group Causal Indicator Modeling Framework to the Reading Comprehension Skills of Third, Seventh, and Tenth Grade Students.

    PubMed

    Tighe, Elizabeth L; Wagner, Richard K; Schatschneider, Christopher

    2015-04-01

    This study demonstrates the utility of applying a causal indicator modeling framework to investigate important predictors of reading comprehension in third, seventh, and tenth grade students. The results indicated that a 4-factor multiple indicator multiple indicator cause (MIMIC) model of reading comprehension provided adequate fit at each grade level. This model included latent predictor constructs of decoding, verbal reasoning, nonverbal reasoning, and working memory and accounted for a large portion of the reading comprehension variance (73% to 87%) across grade levels. Verbal reasoning contributed the most unique variance to reading comprehension at all grade levels. In addition, we fit a multiple group 4-factor MIMIC model to investigate the relative stability (or variability) of the predictor contributions to reading comprehension across development (i.e., grade levels). The results revealed that the contributions of verbal reasoning, nonverbal reasoning, and working memory to reading comprehension were stable across the three grade levels. Decoding was the only predictor that could not be constrained to be equal across grade levels. The contribution of decoding skills to reading comprehension was higher in third grade and then remained relatively stable between seventh and tenth grade. These findings illustrate the feasibility of using MIMIC models to explain individual differences in reading comprehension across the development of reading skills.

  17. Applying a Multiple Group Causal Indicator Modeling Framework to the Reading Comprehension Skills of Third, Seventh, and Tenth Grade Students

    ERIC Educational Resources Information Center

    Tighe, Elizabeth L.; Wagner, Richard K.; Schatschneider, Christopher

    2015-01-01

    This study demonstrates the utility of applying a causal indicator modeling framework to investigate important predictors of reading comprehension in third, seventh, and tenth grade students. The results indicated that a 4-factor multiple indicator multiple indicator cause (MIMIC) model of reading comprehension provided adequate fit at each grade…

  18. Case Study on the Effect of Word Repetition Method Supported by Neurological Affecting Model on Fluent Reading

    ERIC Educational Resources Information Center

    Duran, Erol

    2013-01-01

    This research is a case study which is a qualitative study model and named as example event as well. The purpose of this research is determining the effect of word repetitive reading method supported with neurological affecting model on fluent reading. In this study, False Analysis Inventory was used in order to determine the student's oral…

  19. Reading Competence Development of Poor Readers in a German Elementary School Sample: An Empirical Examination of the Matthew Effect Model

    ERIC Educational Resources Information Center

    Pfost, Maximilian; Dorfler, Tobias; Artelt, Cordula

    2012-01-01

    According to the Matthew effect model, interindividual differences in reading competence between poor and normal readers should become wider as students grow older. The second part of the model assumes that these differential pathways are mainly attributable to differential reading activities. The purpose of this study is to examine whether both…

  20. Molecular Dynamics Modeling of the Thermal Conductivity of Irradiated SiC as a Function of Cascade Overlap

    SciTech Connect

    Crocombette, J.-P.; Dumazer, Guillaume; Hoang, Nguyen Q.; Gao, Fei; Weber, William J.

    2007-01-15

    SiC thermal conductivity is known to decrease under irradiation. To understand this effect, we study the variation of the thermal conductivity of cubic SiC with defect accumulation induced by displacement cascades. We use an empirical potential of the Tersoff type in the framework of non-equilibrium molecular dynamics. The conductivity of SiC is found to decrease with dose, in very good quantitative agreement with low temperature irradiation experiments. The results are analyzed in view of the amorphization states that are created by the cascade accumulation simulations. The calculated conductivity values at lower doses are close to the smallest measured values after high temperature irradiation, indicating that the decrease of the conductivity observed at lower doses is related to the creation of point defects. A subsequent decrease takes place upon further cascade accumulation. It is characteristic of the amorphization of the material and is experimentally observed for low temperature irradiation only.

  1. Approaches to improve the robustness on interdependent networks against cascading failures with load-based model

    NASA Astrophysics Data System (ADS)

    Dong, Zhengcheng; Fang, Yanjun; Tian, Meng; Zhang, Rong

    2015-11-01

    With load-based model, considering the loss of capacity on nodes, we investigate how the coupling strength (many-to-many coupled pattern) and link patterns (one-to-one coupled pattern) can affect the robustness of interdependent networks. In one-to-one coupled pattern, we take into account the properties of degree and betweenness, and adopt four kinds of inter-similarity link patterns and random link pattern. In many-to-many coupled pattern, we propose a novel method to build new networks via adding inter-links (coupled links) on the existing one-to-one coupled networks. For a full investigation on the effects, we conduct two types of attack strategies, i.e. RO-attack (randomly remove only one node) and RF-attack (randomly remove a fraction of nodes). We numerically find that inter-similarity link patterns and bigger coupling strength can effectively improve the robustness under RO-attacks and RF-attacks in some cases. Therefore, the inter-similarity link patterns can be applied during the initial period of network construction. Once the networks are completed, the robustness level can be improved via adding inter-links appropriately without changing the existing inter-links and topologies of networks. We also find that BA-BA topology is a better choice and that it is not useful to infinitely increase the capacity which is defined as the cost of networks.

  2. Coarse graining approach to First principles modeling of radiation cascade in large Fe super-cells

    NASA Astrophysics Data System (ADS)

    Odbadrakh, Khorgolkhuu; Nicholson, Don; Rusanu, Aurelian; Wang, Yang; Stoller, Roger; Zhang, Xiaoguang; Stocks, George

    2012-02-01

    First principles techniques employed to understand systems at an atomistic level are not practical for large systems consisting of millions of atoms. We present an efficient coarse graining approach to bridge the first principles calculations of local electronic properties to classical Molecular Dynamics (MD) simulations of large structures. Local atomic magnetic moments in crystalline Fe are perturbed by radiation generated defects. The effects are most pronounced near the defect core and decay with distance. We develop a coarse grained technique based on the Locally Self-consistent Multiple Scattering (LSMS) method that exploits the near-sightedness of the electron Green function. The atomic positions were determined by MD with an embedded atom force field. The local moments in the neighborhood of the defect cores are calculated with first-principles based on full local structure information. Atoms in the rest of the system are modeled by representative atoms with approximated properties. This work was supported by the Center for Defect Physics, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  3. Modelling reading development through phonological decoding and self-teaching: implications for dyslexia.

    PubMed

    Ziegler, Johannes C; Perry, Conrad; Zorzi, Marco

    2014-01-01

    The most influential theory of learning to read is based on the idea that children rely on phonological decoding skills to learn novel words. According to the self-teaching hypothesis, each successful decoding encounter with an unfamiliar word provides an opportunity to acquire word-specific orthographic information that is the foundation of skilled word recognition. Therefore, phonological decoding acts as a self-teaching mechanism or 'built-in teacher'. However, all previous connectionist models have learned the task of reading aloud through exposure to a very large corpus of spelling-sound pairs, where an 'external' teacher supplies the pronunciation of all words that should be learnt. Such a supervised training regimen is highly implausible. Here, we implement and test the developmentally plausible phonological decoding self-teaching hypothesis in the context of the connectionist dual process model. In a series of simulations, we provide a proof of concept that this mechanism works. The model was able to acquire word-specific orthographic representations for more than 25 000 words even though it started with only a small number of grapheme-phoneme correspondences. We then show how visual and phoneme deficits that are present at the outset of reading development can cause dyslexia in the course of reading development.

  4. Modelling reading development through phonological decoding and self-teaching: implications for dyslexia

    PubMed Central

    Ziegler, Johannes C.; Perry, Conrad; Zorzi, Marco

    2014-01-01

    The most influential theory of learning to read is based on the idea that children rely on phonological decoding skills to learn novel words. According to the self-teaching hypothesis, each successful decoding encounter with an unfamiliar word provides an opportunity to acquire word-specific orthographic information that is the foundation of skilled word recognition. Therefore, phonological decoding acts as a self-teaching mechanism or ‘built-in teacher’. However, all previous connectionist models have learned the task of reading aloud through exposure to a very large corpus of spelling–sound pairs, where an ‘external’ teacher supplies the pronunciation of all words that should be learnt. Such a supervised training regimen is highly implausible. Here, we implement and test the developmentally plausible phonological decoding self-teaching hypothesis in the context of the connectionist dual process model. In a series of simulations, we provide a proof of concept that this mechanism works. The model was able to acquire word-specific orthographic representations for more than 25 000 words even though it started with only a small number of grapheme–phoneme correspondences. We then show how visual and phoneme deficits that are present at the outset of reading development can cause dyslexia in the course of reading development. PMID:24324240

  5. Modelling normal and impaired letter recognition: implications for understanding pure alexic reading.

    PubMed

    Chang, Ya-Ning; Furber, Steve; Welbourne, Stephen

    2012-10-01

    Letter recognition is the foundation of the human reading system. Despite this, it tends to receive little attention in computational modelling of single word reading. Here we present a model that can be trained to recognise letters in various spatial transformations. When presented with degraded stimuli the model makes letter confusion errors that correlate with human confusability data. Analyses of the internal representations of the model suggest that a small set of learned visual feature detectors support the recognition of both upper case and lower case letters in various fonts and transformations. We postulated that a damaged version of the model might be expected to act in a similar manner to patients suffering from pure alexia. Summed error score generated from the model was found to be a very good predictor of the reading times of pure alexic patients, outperforming simple word length, and accounting for 47% of the variance. These findings are consistent with a hypothesis suggesting that impaired visual processing is a key to understanding the strong word-length effects found in pure alexic patients.

  6. Including local rainfall dynamics and uncertain boundary conditions into a 2-D regional-local flood modelling cascade

    NASA Astrophysics Data System (ADS)

    Bermúdez, María; Neal, Jeffrey C.; Bates, Paul D.; Coxon, Gemma; Freer, Jim E.; Cea, Luis; Puertas, Jerónimo

    2016-04-01

    Flood inundation models require appropriate boundary conditions to be specified at the limits of the domain, which commonly consist of upstream flow rate and downstream water level. These data are usually acquired from gauging stations on the river network where measured water levels are converted to discharge via a rating curve. Derived streamflow estimates are therefore subject to uncertainties in this rating curve, including extrapolating beyond the maximum observed ratings magnitude. In addition, the limited number of gauges in reach-scale studies often requires flow to be routed from the nearest upstream gauge to the boundary of the model domain. This introduces additional uncertainty, derived not only from the flow routing method used, but also from the additional lateral rainfall-runoff contributions downstream of the gauging point. Although generally assumed to have a minor impact on discharge in fluvial flood modeling, this local hydrological input may become important in a sparse gauge network or in events with significant local rainfall. In this study, a method to incorporate rating curve uncertainty and the local rainfall-runoff dynamics into the predictions of a reach-scale flood inundation model is proposed. Discharge uncertainty bounds are generated by applying a non-parametric local weighted regression approach to stage-discharge measurements for two gauging stations, while measured rainfall downstream from these locations is cascaded into a hydrological model to quantify additional inflows along the main channel. A regional simplified-physics hydraulic model is then applied to combine these inputs and generate an ensemble of discharge and water elevation time series at the boundaries of a local-scale high complexity hydraulic model. Finally, the effect of these rainfall dynamics and uncertain boundary conditions are evaluated on the local-scale model. Improvements in model performance when incorporating these processes are quantified using observed

  7. Cascaded-cladding-pumped cascaded Raman fiber amplifier.

    PubMed

    Jiang, Huawei; Zhang, Lei; Feng, Yan

    2015-06-01

    The conversion efficiency of double-clad Raman fiber laser is limited by the cladding-to-core area ratio. To get high conversion efficiency, the inner-cladding-to-core area ratio has to be less than about 8, which limits the brightness enhancement. To overcome the problem, a cascaded-cladding-pumped cascaded Raman fiber laser with multiple-clad fiber as the Raman gain medium is proposed. A theoretical model of Raman fiber amplifier with multiple-clad fiber is developed, and numerical simulation proves that the proposed scheme can improve the conversion efficiency and brightness enhancement of cladding pumped Raman fiber laser.

  8. Spatial distribution and dose-response relationship for different operation modes in a reaction-diffusion model of the MAPK cascade

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Yi, Ming; Liu, Yan

    2011-10-01

    The mitogen-activated protein kinase (MAPK) cascade plays a critical role in the control of cell growth. Deregulation of this pathway contributes to the development of many cancers. To better understand its signal transduction, we constructed a reaction-diffusion model for the MAPK pathway. We modeled the three layers of phosphorylation-dephosphorylation reactions and diffusion processes from the cell membrane to the nucleus. Based on different types of feedback in the MAPK cascade, four operation modes are introduced. For each of the four modes, spatial distributions and dose-response curves of active kinases (i.e. ppMAPK) are explored by numerical simulation. The effects of propagation length, diffusion coefficient and feedback strength on the pathway dynamics are investigated. We found that intrinsic bistability in the MAPK cascade can generate a traveling wave of ppMAPK with constant amplitude when the propagation length is short. ppMAPK in this mode of intrinsic bistability decays more slowly than it does in all other modes as the propagation length increases. Moreover, we examined the global and local responses to Ras-GTP of these four modes, and demonstrated how the shapes of these dose-response curves change as the propagation length increases. Also, we found that larger diffusion constant gives a higher response level on the zero-order regime and makes the ppMAPK profiles flatter under strong Ras-GTP stimulus. Furthermore, we observed that spatial responses of ppMAPK are more sensitive to negative feedback than to positive feedback in the broader signal range. Finally, we showed how oscillatory signals pass through the kinase cascade, and found that high frequency signals are damped faster than low frequency ones.

  9. The Effects of Modeling and Repeated Taped Reading Instruction on the Learning Disabled Child as Ways To Improve Reading Comprehension Fluency and Word Recognition.

    ERIC Educational Resources Information Center

    Rokicki, Anne L.

    This practicum focused on the use of repeated taped reading instruction with modeling to improve fluency, comprehension, and automatic word recognition in five students (ages 11-13 years) with learning disabilities for a period of 10 weeks. The instruction also involved the teacher giving corrective feedback and having the students answer story…

  10. Contingency Analysis of Cascading Line Outage Events

    SciTech Connect

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  11. Cascading dynamics in modular networks

    NASA Astrophysics Data System (ADS)

    Galstyan, Aram; Cohen, Paul

    2007-03-01

    In this paper we study a simple cascading process in a structured heterogeneous population, namely, a network composed of two loosely coupled communities. We demonstrate that under certain conditions the cascading dynamics in such a network has a two-tiered structure that characterizes activity spreading at different rates in the communities. We study the dynamics of the model using both simulations and an analytical approach based on annealed approximation and obtain good agreement between the two. Our results suggest that network modularity might have implications in various applications, such as epidemiology and viral marketing.

  12. Modeling the Relations Among Morphological Awareness Dimensions, Vocabulary Knowledge, and Reading Comprehension in Adult Basic Education Students

    PubMed Central

    Tighe, Elizabeth L.; Schatschneider, Christopher

    2016-01-01

    This study extended the findings of Tighe and Schatschneider (2015) by investigating the predictive utility of separate dimensions of morphological awareness as well as vocabulary knowledge to reading comprehension in adult basic education (ABE) students. We competed two- and three-factor structural equation models of reading comprehension. A three-factor model of real word morphological awareness, pseudoword morphological awareness, and vocabulary knowledge emerged as the best fit and accounted for 79% of the reading comprehension variance. The results indicated that the constructs contributed jointly to reading comprehension; however, vocabulary knowledge was the only potentially unique predictor (p = 0.052), accounting for an additional 5.6% of the variance. This study demonstrates the feasibility of applying a latent variable modeling approach to examine individual differences in the reading comprehension skills of ABE students. Further, this study replicates the findings of Tighe and Schatschneider (2015) on the importance of differentiating among dimensions of morphological awareness in this population. PMID:26869981

  13. On the Evidence of Theory: Close Reading as a Disciplinary Model for Writing about Teaching and Learning

    ERIC Educational Resources Information Center

    Bass, Randy; Linkon, Sherry Lee

    2008-01-01

    While some literary scholars claim that their discipline's research practices do not fit the scholarship of teaching and learning, close reading--the signature critical practice of literary studies--provides a useful model. Close reading involves not only attention to the text but also the integration of text and theory. This article analyzes how…

  14. Elementary School ELLs' Reading Skill Profiles Using Cognitive Diagnosis Modeling: Roles of Length of Residence and Home Language Environment

    ERIC Educational Resources Information Center

    Jang, Eunice Eunhee; Dunlop, Maggie; Wagner, Maryam; Kim, Youn-Hee; Gu, Zhimei

    2013-01-01

    The study examined differences in reading achievement and mastery skill development among Grade-6 students with different language background profiles, using cognitive diagnosis modeling applied to large-scale provincial reading test performance data. Our analyses revealed that students residing in various home language environments show different…

  15. Growing Readers: A Hierarchical Linear Model of Children's Reading Growth During the First 2 Years of School

    ERIC Educational Resources Information Center

    McCoach, D. Betsy; O'Connell, Ann A.; Reis, Sally M.; Levitt, Heather A.

    2006-01-01

    Using the first 4 waves of data from the Early Childhood Longitudinal Study-Kindergarten cohort (ECLS-K), this piecewise 3-level (time-student-school) growth-curve model provides a portrait of students' reading growth over the first 2 years of school. On average, students make much greater reading gains in 1st grade than they do in kindergarten.…

  16. Experimental determination of unsteady blade element aerodynamics in cascades. Volume 2: Translation mode cascade

    NASA Technical Reports Server (NTRS)

    Riffel, R. E.; Rothrock, M. D.

    1980-01-01

    A two dimensional cascade of harmonically oscillating airfoils was designed to model a near tip section from a rotor which was known to have experienced supersonic translational model flutter. This five bladed cascade had a solidity of 1.52 and a setting angle of 0.90 rad. Unique graphite epoxy airfoils were fabricated to achieve the realistic high reduced frequency level of 0.15. The cascade was tested over a range of static pressure ratios approximating the blade element operating conditions of the rotor along a constant speed line which penetrated the flutter boundary. The time steady and time unsteady flow field surrounding the center cascade airfoil were investigated.

  17. Moving beyond No Child Left Behind with the Merged Model for Reading Instruction

    ERIC Educational Resources Information Center

    Pruisner, Peggy

    2009-01-01

    As a result of the Reading First Program of the No Child Left Behind Act (NCLB), the view of reading has narrowed. Individual state's Reading First professional development programs, and hence reading teachers across the United States, have spent the six years since the funding of the program in 2002 focusing beginning and developmental reading on…

  18. A Model Critical Reading Lesson for Secondary High-Risk Students.

    ERIC Educational Resources Information Center

    Haney, Gail; Thistlethwaite, Linda

    1991-01-01

    This article defines critical reading, discusses associated frameworks, and lists considerations for choosing topics and reading materials. A sample critical reading lesson using a "mapping" approach with a reading on euthanasia demonstrates guiding secondary learning-disabled students in critical reading. (DB)

  19. Reading Guided by Automated Graphical Representations: How Model-Based Text Visualizations Facilitate Learning in Reading Comprehension Tasks

    ERIC Educational Resources Information Center

    Pirnay-Dummer, Pablo; Ifenthaler, Dirk

    2011-01-01

    Our study integrates automated natural language-oriented assessment and analysis methodologies into feasible reading comprehension tasks. With the newly developed T-MITOCAR toolset, prose text can be automatically converted into an association net which has similarities to a concept map. The "text to graph" feature of the software is based on…

  20. Opioid-receptor (OR) signaling cascades in rat cerebral cortex and model cell lines: the role of plasma membrane structure.

    PubMed

    Ujčíková, H; Brejchová, J; Vošahlíková, M; Kagan, D; Dlouhá, K; Sýkora, J; Merta, L; Drastichová, Z; Novotný, J; Ostašov, P; Roubalová, L; Parenti, M; Hof, M; Svoboda, P

    2014-01-01

    Large number of extracellular signals is received by plasma membrane receptors which, upon activation, transduce information into the target cell interior via trimeric G-proteins (GPCRs) and induce activation or inhibition of adenylyl cyclase enzyme activity (AC). Receptors for opioid drugs such as morphine (micro-OR, delta-OR and kappa-OR) belong to rhodopsin family of GPCRs. Our recent results indicated a specific up-regulation of AC I (8-fold) and AC II (2.5-fold) in plasma membranes (PM) isolated from rat brain cortex exposed to increasing doses of morphine (10-50 mg/kg) for 10 days. Increase of ACI and ACII represented the specific effect as the amount of ACIII-ACIX, prototypical PM marker Na, K-ATPase and trimeric G-protein alpha and beta subunits was unchanged. The up-regulation of ACI and ACII faded away after 20 days since the last dose of morphine. Proteomic analysis of these PM indicated that the brain cortex of morphine-treated animals cannot be regarded as being adapted to this drug because significant up-regulation of proteins functionally related to oxidative stress and alteration of brain energy metabolism occurred. The number of delta-OR was increased 2-fold and their sensitivity to monovalent cations was altered. Characterization of delta-OR-G-protein coupling in model HEK293 cell line indicated high ability of lithium to support affinity of delta-OR response to agonist stimulation. Our studies of PM structure and function in context with desensitization of GPCRs action were extended by data indicating participation of cholesterol-enriched membrane domains in agonist-specific internalization of delta-OR. In HEK293 cells stably expressing delta-OR-G(i)1alpha fusion protein, depletion of PM cholesterol was associated with the decrease in affinity of G-protein response to agonist stimulation, whereas maximum response was unchanged. Hydrophobic interior of isolated PM became more "fluid", chaotically organized and accessible to water molecules

  1. Phenotypic and evolutionary implications of modulating the ERK-MAPK cascade using the dentition as a model

    PubMed Central

    Marangoni, Pauline; Charles, Cyril; Tafforeau, Paul; Laugel-Haushalter, Virginie; Joo, Adriane; Bloch-Zupan, Agnès; Klein, Ophir D.; Viriot, Laurent

    2015-01-01

    The question of phenotypic convergence across a signalling pathway has important implications for both developmental and evolutionary biology. The ERK-MAPK cascade is known to play a central role in dental development, but the relative roles of its components remain unknown. Here we investigate the diversity of dental phenotypes in Spry2−/−, Spry4−/−, and Rsk2−/Y mice, including the incidence of extra teeth, which were lost in the mouse lineage 45 million years ago (Ma). In addition, Sprouty-specific anomalies mimic a phenotype that is absent in extant mice but present in mouse ancestors prior to 9 Ma. Although the mutant lines studied display convergent phenotypes, each gene has a specific role in tooth number determination and crown patterning. The similarities found between teeth in fossils and mutants highlight the pivotal role of the ERK-MAPK cascade during the evolution of the dentition in rodents. PMID:26123406

  2. Phenotypic and evolutionary implications of modulating the ERK-MAPK cascade using the dentition as a model

    NASA Astrophysics Data System (ADS)

    Marangoni, Pauline; Charles, Cyril; Tafforeau, Paul; Laugel-Haushalter, Virginie; Joo, Adriane; Bloch-Zupan, Agnès; Klein, Ophir D.; Viriot, Laurent

    2015-06-01

    The question of phenotypic convergence across a signalling pathway has important implications for both developmental and evolutionary biology. The ERK-MAPK cascade is known to play a central role in dental development, but the relative roles of its components remain unknown. Here we investigate the diversity of dental phenotypes in Spry2-/-, Spry4-/-, and Rsk2-/Y mice, including the incidence of extra teeth, which were lost in the mouse lineage 45 million years ago (Ma). In addition, Sprouty-specific anomalies mimic a phenotype that is absent in extant mice but present in mouse ancestors prior to 9 Ma. Although the mutant lines studied display convergent phenotypes, each gene has a specific role in tooth number determination and crown patterning. The similarities found between teeth in fossils and mutants highlight the pivotal role of the ERK-MAPK cascade during the evolution of the dentition in rodents.

  3. Cascading failures and the emergence of cooperation in evolutionary-game based models of social and economical networks

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Xu; Lai, Ying-Cheng; Armbruster, Dieter

    2011-09-01

    We study catastrophic behaviors in large networked systems in the paradigm of evolutionary games by incorporating a realistic "death" or "bankruptcy" mechanism. We find that a cascading bankruptcy process can arise when defection strategies exist and individuals are vulnerable to deficit. Strikingly, we observe that, after the catastrophic cascading process terminates, cooperators are the sole survivors, regardless of the game types and of the connection patterns among individuals as determined by the topology of the underlying network. It is necessary that individuals cooperate with each other to survive the catastrophic failures. Cooperation thus becomes the optimal strategy and absolutely outperforms defection in the game evolution with respect to the "death" mechanism. Our results can be useful for understanding large-scale catastrophe in real-world systems and in particular, they may yield insights into significant social and economical phenomena such as large-scale failures of financial institutions and corporations during an economic recession.

  4. South Cascade Glacier bibliography

    SciTech Connect

    Fountain, A.G.; Fulk, M.A.

    1984-01-01

    South Cascade Glacier, in Washington State, resides in a well-defined basin with mainly unglacierized divides making it ideal for most glaciological and hydrological studies. This bibliography is divided into three cateogories: (1) studies done about South Cascade Glacier specifically; (2) studies that use data from South Cascade Glacier but do not focus on or give insight to the glacier itself; and (3) instrumentation studies and non-glacier projects including snow studies done in the basin. (ACR)

  5. Component criticality in failure cascade processes of network systems.

    PubMed

    Zio, Enrico; Sansavini, Giovanni

    2011-08-01

    In this work, specific indicators are used to characterize the criticality of components in a network system with respect to their contribution to failure cascade processes. A realistic-size network is considered as reference case study. Three different models of cascading failures are analyzed, differing both on the failure load distribution logic and on the cascade triggering event. The criticality indicators are compared to classical measures of topological centrality to identify the one most characteristic of the cascade processes considered.

  6. Modelling water quality and quantity with the influence of inter-basin water diversion projects and cascade reservoirs in the Middle-lower Hanjiang River

    NASA Astrophysics Data System (ADS)

    Wang, Yonggui; Zhang, Wanshun; Zhao, Yanxin; Peng, Hong; Shi, Yingyuan

    2016-10-01

    The effects of inter-basin water diversion projects and cascade reservoirs are typically complex and challenging, as the uncertain temporal-spatial variation of both water quality and quantity. The purpose of this paper is to propose a coupled 1D hydrodynamic model with water-quality model to analyze the effects of current and future inter-basin water diversion projects, i.e., South-to-North Water Diversion Project (SNWD) and Yangtze-Hanjiang Water Diversion Project (YHWD), and cascade reservoirs (CRS) on water quantity and quality in the middle-lower Hanjiang River. Considering water use and pollution contribution, the middle-lower Hanjaing River basin is generalized and divided into 18 land use units with tributaries, reservoirs and water exchanges. Each unit is considered with the processes of lateral inflow, point and non-point pollution loads, irrigation return flow, and stream-aquifer exchanges in the model. The long-term time series from 1956 to 1998 of water quality and quantity with four engineering scenarios is collected. The validation of results shows that the relative errors between the simulated and observed values at certain control sections are within 5% for water levels and 20% for water quality. The water level will be decreased by 0.38-0.65 m (decreasing rate 0.44-2.68%), the annual runoff will be significantly decreased over 4 billion m3 and the water quality will be changed after the SNWD. As a compensation project, the YHWD partly offsets the negative effects of the SNWD in water flow rate, but at the same time it rises the water level and reduces the flow velocity. This, together with the effect of cascade reservoirs, leads to water quality concentration increasing and deteriorating to Grade IV of the Chinese Surface Water Quality Criteria. The water resource reduction and water quality problems in the Middle-lower Hanjiang River require attention after these projects.

  7. A Longitudinal Study on State Mathematics and Reading Assessments: Comparisons of Growth Models on Students' Achievement Scores

    ERIC Educational Resources Information Center

    Chiu, Pui Chi

    2012-01-01

    This study examines student growth on mathematics and reading assessments across academic years (Spring 2006 through Spring 2009) using three different growth models: hierarchical linear model (HLM), value-added model (VAM), and student growth percentile model (SGP). Comparisons across these three growth models were conducted to investigate the…

  8. Cascade-able spin torque logic gates with input-output isolation

    NASA Astrophysics Data System (ADS)

    Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.

    2015-06-01

    Spin torque majority gate (STMG) is one of the promising options for beyond-complementary metal-oxide-semiconductor non-volatile logic circuits for normally-off computing. Modeling of prior schemes demonstrated logic completeness using majority operation and nonlinear transfer characteristics. However significant problems arose with cascade-ability and input output isolation manifesting as domain walls (DWs) stopping, reflecting off ends of wires or propagating back to the inputs. We introduce a new scheme to enable cascade-ability and isolation based on (a) in-plane DW automotion in interconnects, (b) exchange coupling of magnetization between two FM layers, and (c) ‘round-about’ topology for the majority gate. We performed micro-magnetic simulations that demonstrate switching operation of this STMG scheme. These circuits were verified to enable isolation of inputs from output signals and to be cascade-able without limitations.

  9. Multiplicities of secondaries in interactions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion and the cascade evaporation model

    NASA Technical Reports Server (NTRS)

    Dudkin, V. E; Kovalev, E. E.; Nefedov, N. A.; Antonchik, V. A.; Bogdanov, S. D.; Ostroumov, V. I.; Crawford, H. J.; Benton, E. V.

    1995-01-01

    A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of Fe-56 nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases.

  10. Multiplicities of secondaries in interactions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion and the cascade evaporation model

    SciTech Connect

    Dudkin, V.E; Kovalev, E.E.; Nefedov, N.A.; Antonchik, V.A.; Bogdanov, S.D.; Ostroumov, V.I.; Crawford, H.J.; Benton, E.V. ||

    1995-03-01

    A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of Fe-56 nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases.

  11. PDEGEM: Modeling non-uniform read distribution in RNA-Seq data

    PubMed Central

    2015-01-01

    Background RNA-Seq is a powerful new technology to comprehensively analyze the transcriptome of any given cells. An important task in RNA-Seq data analysis is quantifying the expression levels of all transcripts. Although many methods have been introduced and much progress has been made, a satisfactory solution remains be elusive. Results In this article, we borrow the idea from the Positional Dependent Nearest Neighborhood (PDNN) model, originally developed for analyzing microarray data, to model the non-uniformity of read distribution in RNA-seq data. We propose a robust nonlinear regression model named PDEGEM, a Positional Dependent Energy Guided Expression Model to estimate the abundance of transcripts. Using real data, we find that the PDEGEM fits the data better than mseq in all three real datasets we tested. We also find that the expression measure obtained using PDEGEM showed higher correlation with that obtained from alterative assays for quantifying gene and isoform expressions. Conclusions Based on these results, we believe that our PDEGEM can improve the accuracy in modeling and estimating the transcript abundance and isoform expression in RNA-Seq data. Additionally, although the stacking energy and positional weight of the PDEGEM are relatively related to sequencing platforms and species, they share some common trends, which indicates that the PDEGEM could partly reflect the mechanism of DNA binding between the template strain and the new synthesized read. The PDEGEM model can be freely downloaded at: http://www.math.pku.edu.cn/teachers/dengmh/PDEGEM. PMID:26044773

  12. Cascaded automatic target recognition (Cascaded ATR)

    NASA Astrophysics Data System (ADS)

    Walls, Bradley

    2010-04-01

    The global war on terror has plunged US and coalition forces into a battle space requiring the continuous adaptation of tactics and technologies to cope with an elusive enemy. As a result, technologies that enhance the intelligence, surveillance, and reconnaissance (ISR) mission making the warfighter more effective are experiencing increased interest. In this paper we show how a new generation of smart cameras built around foveated sensing makes possible a powerful ISR technique termed Cascaded ATR. Foveated sensing is an innovative optical concept in which a single aperture captures two distinct fields of view. In Cascaded ATR, foveated sensing is used to provide a coarse resolution, persistent surveillance, wide field of view (WFOV) detector to accomplish detection level perception. At the same time, within the foveated sensor, these detection locations are passed as a cue to a steerable, high fidelity, narrow field of view (NFOV) detector to perform recognition level perception. Two new ISR mission scenarios, utilizing Cascaded ATR, are proposed.

  13. Numerical computation of aerodynamics and heat transfer in a turbine cascade and a turn-around duct using advanced turbulence models

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, B.; Luo, J.

    1993-01-01

    The objective of this research is to develop turbulence models to predict the flow and heat transfer fields dominated by the curvature effect such as those encountered in turbine cascades and turn-around ducts. A Navier-Stokes code has been developed using an explicit Runge-Kutta method with a two layer k-epsilon/ARSM (Algebraic Reynolds Stress Model), Chien's Low Reynolds Number (LRN) k-epsilon model and Coakley's LRN q-omega model. The near wall pressure strain correlation term was included in the ARSM. The formulation is applied to Favre-averaged N-S equations and no thin-layer approximations are made in either the mean flow or turbulence transport equations. Anisotropic scaling of artificial dissipation terms was used. Locally variable timestep was also used to improve convergence. Detailed comparisons were made between computations and data measured in a turbine cascade by Arts et al. at Von Karman Institute. The surface pressure distributions and wake profiles were predicted well by all the models. The blade heat transfer is predicted well by k-epsilon/ARSM model, as well as the k-epsilon model. It's found that the onset of boundary layer transition on both surfaces is highly dependent upon the level of local freestream turbulence intensity, which is strongly influenced by the streamline curvature. Detailed computation of the flow in the turn around duct has been carried out and validated against the data by Monson as well as Sandborn. The computed results at various streamwise locations both on the concave and convex sides are compared with flow and turbulence data including the separation zone on the inner well. The k-epsilon/ARSM model yielded relatively better results than the two-equation turbulence models. A detailed assessment of the turbulence models has been made with regard to their applicability to curved flows.

  14. Cascades on clique-based graphs

    NASA Astrophysics Data System (ADS)

    Hackett, Adam; Gleeson, James P.

    2013-06-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly clustered random graphs introduced by Gleeson [J. P. Gleeson, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.80.036107 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  15. A Developmental Model of Reading Acquisition Based upon Early Scaffolding Errors and Subsequent Vowel Inferences

    ERIC Educational Resources Information Center

    Savage, Robert; Stuart, Morag

    2006-01-01

    This paper investigates the processes that predict reading acquisition. Associations between (a) scaffolding errors (e.g., "torn" misread as "town" or "tarn"), other reading errors, and later reading and (b) vowel and rime inferences and later reading were explored. To assess both of these issues, 50 6-year-old children were shown a number of CVC…

  16. Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA

    USGS Publications Warehouse

    Dzurisin, Daniel; Lisowski, Michael; Wicks, Charles W.; Poland, Michael P.; Endo, Elliot T.

    2006-01-01

    Tumescence at the Three Sisters volcanic center began sometime between summer 1996 and summer 1998 and was discovered in April 2001 using interferometric synthetic aperture radar (InSAR). Swelling is centered about 5 km west of the summit of South Sister, a composite basaltic-andesite to rhyolite volcano that last erupted between 2200 and 2000 yr ago, and it affects an area ∼20 km in diameter within the Three Sisters Wilderness. Yearly InSAR observations show that the average maximum displacement rate was 3–5 cm/yr through summer 2001, and the velocity of a continuous GPS station within the deforming area was essentially constant from June 2001 to June 2004. The background level of seismic activity has been low, suggesting that temperatures in the source region are high enough or the strain rate has been low enough to favor plastic deformation over brittle failure. A swarm of about 300 small earthquakes (Mmax = 1.9) in the northeast quadrant of the deforming area on March 23–26, 2004, was the first notable seismicity in the area for at least two decades. The U.S. Geological Survey (USGS) established tilt-leveling and EDM networks at South Sister in 1985–1986, resurveyed them in 2001, the latter with GPS, and extended them to cover more of the deforming area. The 2001 tilt-leveling results are consistent with the inference drawn from InSAR that the current deformation episode did not start before 1996, i.e., the amount of deformation during 1995–2001 from InSAR fully accounts for the net tilt at South Sister during 1985–2001 from tilt-leveling. Subsequent InSAR, GPS, and leveling observations constrain the source location, geometry, and inflation rate as a function of time. A best-fit source model derived from simultaneous inversion of all three datasets is a dipping sill located 6.5 ± 2.5 km below the surface with a volume increase of 5.0 × 106 ± 1.5 × 106m3/yr (95% confidence limits). The most likely cause of tumescence is a pulse of

  17. Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA

    NASA Astrophysics Data System (ADS)

    Dzurisin, Daniel; Lisowski, Michael; Wicks, Charles W.; Poland, Michael P.; Endo, Elliot T.

    2006-02-01

    Tumescence at the Three Sisters volcanic center began sometime between summer 1996 and summer 1998 and was discovered in April 2001 using interferometric synthetic aperture radar (InSAR). Swelling is centered about 5 km west of the summit of South Sister, a composite basaltic-andesite to rhyolite volcano that last erupted between 2200 and 2000 yr ago, and it affects an area ˜20 km in diameter within the Three Sisters Wilderness. Yearly InSAR observations show that the average maximum displacement rate was 3-5 cm/yr through summer 2001, and the velocity of a continuous GPS station within the deforming area was essentially constant from June 2001 to June 2004. The background level of seismic activity has been low, suggesting that temperatures in the source region are high enough or the strain rate has been low enough to favor plastic deformation over brittle failure. A swarm of about 300 small earthquakes ( Mmax = 1.9) in the northeast quadrant of the deforming area on March 23-26, 2004, was the first notable seismicity in the area for at least two decades. The U.S. Geological Survey (USGS) established tilt-leveling and EDM networks at South Sister in 1985-1986, resurveyed them in 2001, the latter with GPS, and extended them to cover more of the deforming area. The 2001 tilt-leveling results are consistent with the inference drawn from InSAR that the current deformation episode did not start before 1996, i.e., the amount of deformation during 1995-2001 from InSAR fully accounts for the net tilt at South Sister during 1985-2001 from tilt-leveling. Subsequent InSAR, GPS, and leveling observations constrain the source location, geometry, and inflation rate as a function of time. A best-fit source model derived from simultaneous inversion of all three datasets is a dipping sill located 6.5 ± 2.5 km below the surface with a volume increase of 5.0 × 10 6 ± 1.5 × 10 6 m 3/yr (95% confidence limits). The most likely cause of tumescence is a pulse of basaltic magma

  18. Theory of cascade refrigeration

    NASA Astrophysics Data System (ADS)

    Quack, Hans H.

    2012-06-01

    The maximum difference between the warm and cold temperature of a refrigeration cycle is limited by properties of the refrigerant and/or losses associated with the transport of the refrigerant. For larger temperature differences, one has to arrange several refrigeration cycles "above" each other, each cycle spanning a certain temperature difference. This approach is called cascade refrigeration and has played an important role in the history of cryogenics. For a theory of cascade refrigeration it is helpful to define a general one-stage non-reversible refrigeration step and to visualize it within the temperature-entropy diagram. Then one can combine several one-stage cycles to a cascade. There exist two types of cascades: "Full" cascades, where all entropy gains of a lower stage are transferred to the next higher temperature stage, and "partial" cascades, where each single cycle goes up to ambient temperature, where a part of the entropy gain is removed, and only the rest of the entropy gain is transferred to the next higher temperature stage. In cryogenic refrigeration "partial" cascades are generally more efficient than "full" cascades.

  19. Bankruptcy Cascades in Interbank Markets

    PubMed Central

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  20. Bankruptcy cascades in interbank markets.

    PubMed

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  1. Training Inference Making Skills Using a Situation Model Approach Improves Reading Comprehension

    PubMed Central

    Bos, Lisanne T.; De Koning, Bjorn B.; Wassenburg, Stephanie I.; van der Schoot, Menno

    2016-01-01

    This study aimed to enhance third and fourth graders’ text comprehension at the situation model level. Therefore, we tested a reading strategy training developed to target inference making skills, which are widely considered to be pivotal to situation model construction. The training was grounded in contemporary literature on situation model-based inference making and addressed the source (text-based versus knowledge-based), type (necessary versus unnecessary for (re-)establishing coherence), and depth of an inference (making single lexical inferences versus combining multiple lexical inferences), as well as the type of searching strategy (forward versus backward). Results indicated that, compared to a control group (n = 51), children who followed the experimental training (n = 67) improved their inference making skills supportive to situation model construction. Importantly, our training also resulted in increased levels of general reading comprehension and motivation. In sum, this study showed that a ‘level of text representation’-approach can provide a useful framework to teach inference making skills to third and fourth graders. PMID:26913014

  2. Training Inference Making Skills Using a Situation Model Approach Improves Reading Comprehension.

    PubMed

    Bos, Lisanne T; De Koning, Bjorn B; Wassenburg, Stephanie I; van der Schoot, Menno

    2016-01-01

    This study aimed to enhance third and fourth graders' text comprehension at the situation model level. Therefore, we tested a reading strategy training developed to target inference making skills, which are widely considered to be pivotal to situation model construction. The training was grounded in contemporary literature on situation model-based inference making and addressed the source (text-based versus knowledge-based), type (necessary versus unnecessary for (re-)establishing coherence), and depth of an inference (making single lexical inferences versus combining multiple lexical inferences), as well as the type of searching strategy (forward versus backward). Results indicated that, compared to a control group (n = 51), children who followed the experimental training (n = 67) improved their inference making skills supportive to situation model construction. Importantly, our training also resulted in increased levels of general reading comprehension and motivation. In sum, this study showed that a 'level of text representation'-approach can provide a useful framework to teach inference making skills to third and fourth graders.

  3. The anatomical foundations of acquired reading disorders: a neuropsychological verification of the dual-route model of reading.

    PubMed

    Ripamonti, E; Aggujaro, S; Molteni, F; Zonca, G; Frustaci, M; Luzzatti, C

    2014-07-01

    In this study we investigated the neural correlates of acquired reading disorders through an anatomo-correlative procedure of the lesions of 59 focal brain damaged patients suffering from acquired surface, phonological, deep, undifferentiated dyslexia and pure alexia. Two reading tasks, one of words and nonwords and one of words with unpredictable stress position, were used for this study. We found that surface dyslexia was predominantly associated with left temporal lesions, while in phonological dyslexia the lesions overlapped in the left insula and the left inferior frontal gyrus (pars opercularis) and that pure alexia was associated with lesions in the left fusiform gyrus. A number of areas and white matter tracts, which seemed to involve processing along both the lexical and the sublexical routes, were identified for undifferentiated dyslexia. Two cases of deep dyslexia with relatively dissimilar anatomical correlates were studied, one compatible with Coltheart's right-hemisphere hypothesis (1980) whereas the other could be interpreted in the context of Morton and Patterson's (1980), multiply-damaged left-hemisphere hypothesis. In brief, the results of this study are only partially consistent with the current state of the art, and propose new and stimulating challenges; indeed, based on these results we suggest that different types of acquired dyslexia may ensue after different cortical damage, but white matter disconnection may play a crucial role in some cases.

  4. Reconsidering the simple view of reading in an intriguing case of equivalent models: commentary on Tunmer and Chapman (2012).

    PubMed

    Wagner, Richard K; Herrera, Sarah K; Spencer, Mercedes; Quinn, Jamie M

    2015-01-01

    Recently, Tunmer and Chapman provided an alternative model of how decoding and listening comprehension affect reading comprehension that challenges the simple view of reading. They questioned the simple view's fundamental assumption that oral language comprehension and decoding make independent contributions to reading comprehension by arguing that one component of oral language comprehension (vocabulary) affects decoding. They reported results from hierarchical regression analyses, exploratory factor analysis, and structural equation modeling to justify their conclusion. Their structural equation modeling results provided the strongest and most direct test of their alternative view. However, they incorrectly specified their simple view model. When correctly specified, the simple view of reading model and an alternative model in which listening comprehension affects decoding provide identically good fits to the data. This results from the fact that they are equivalent models. Although Tunmer and Chapman's results do not support their assertion that a model in which oral language comprehension affects decoding provides a better fit to their data, the presence of equivalent models provides an ironic twist: The mountain of evidence that supports the simple view of reading provides equivalent support to their alternative interpretation. Additional studies are needed to differentiate these two theoretical accounts.

  5. Reading materials for post-literacy: The development and testing of a model of social writing

    NASA Astrophysics Data System (ADS)

    Bhola, Harbans S.

    1989-12-01

    A model of social writing, for use in writing socially relevant, easy-to-read, follow-up books for neo-literate adults, is presented. The model was fully developed and tested in the context of a series of writers' workshops during 1981-87; and incorporates all of the three aspects of writing: the expressive, the cognitive, and the social. Specifically, the following elements are included: selection of subject and topic within a dialectic of national development needs and community learning needs; negotiable definitions of general and specific objectives; acquiring knowledge of subject matter, and establishing necessary collaboration with subject-matter specialists; content planning to choose content and language of discourse, participatively with the future community of readers; choice of treatment of content as didactic or dramatic; outlining of manuscript as argument, dialogue or story; writing easy-to-read yet interesting materials; trying out the manuscript and making revisions; working with the illustrator and the editor; and preparing the manuscript for printing. Both the development and the testing of the model involved reflection-in-action and not stand-alone research exercises. The successful use of the model in workshops to train writers of post-literacy materials provided one source of support for the model. A comparison of this model of social writing with other models of writing available in literature has provided further support for the conceptual and procedural structure of the model. Transfers of the model to other cultural settings as well as to the writing of other types of educational materials, such as distance education texts and units, have also proved effective.

  6. A multidomain cascade model of early childhood risk factors associated with oppositional defiant disorder symptoms in a community sample of 6-year-olds.

    PubMed

    Lavigne, John V; Gouze, Karen R; Hopkins, Joyce; Bryant, Fred B

    2016-11-01

    The present study examined a cascade model of age 4 and 5 contextual, parent, parenting, and child factors on symptoms of oppositional defiant disorder (ODD) at age 6 in a diverse community sample of 796 children. Contextual factors include socioeconomic status, family stress, and conflict; parent factors included parental depression; parenting factors included parental hostility, support, and scaffolding skills; child factors included child effortful control (EC), negative affect (NA), and sensory regulation. Direct effects of age 5 conflict, hostility, scaffolding, EC, and NA were found. Significant indirect, cascading effects on age 6 ODD symptom levels were noted for age 4 socioeconomic status via age 5 conflict and scaffolding skills; age 4 parental depression via age 5 child NA; age 4 parental hostility and support via age 5 EC; age 4 support via age 5 EC; and age 4 attachment via age 5 EC. Parenting contributed to EC, and the age 5 EC effects on subsequent ODD symptom levels were distinct from age 5 parental contributions. Scaffolding and ODD symptoms may have a reciprocal relationship. These results highlight the importance of using a multidomain model to examine factors associated with ODD symptoms early in the child's grammar school years.

  7. Transition modelling implications in the CFD analysis of a turbine nozzle vane cascade tested over a range of Mach and Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Marconcini, Michele; Pacciani, Roberto; Arnone, Andrea

    2015-11-01

    The aerodynamic performance of a gas turbine nozzle vane cascade was investigated over a range of Mach and Reynolds numbers. The work is part of a vast research project aimed at the analysis of fluid dynamics and heat transfer phenomena in cooled blades. In this paper computed results on the "solid vane" (without cooling devices) are presented and discussed in comparison with experimental data. Detailed measurements were provided by the University of Bergamo where the experimental campaign was carried out by means of a subsonic wind tunnel. The impact of boundary layer transition is investigated by using a novel laminar kinetic energy transport model and the widely used Langtry-Menter γ- Re θ,t model. The comparison between calculations and measurements is presented in terms of blade loading distributions, total pressure loss coefficient contours downstream of the cascade, and velocity/turbulence-intensity profiles within the boundary layer at selected blade surface locations at mid-span. It will be shown how transitional calculations compare favorably with experiments.

  8. Dynamics robustness of cascading systems.

    PubMed

    Young, Jonathan T; Hatakeyama, Tetsuhiro S; Kaneko, Kunihiko

    2017-03-01

    A most important property of biochemical systems is robustness. Static robustness, e.g., homeostasis, is the insensitivity of a state against perturbations, whereas dynamics robustness, e.g., homeorhesis, is the insensitivity of a dynamic process. In contrast to the extensively studied static robustness, dynamics robustness, i.e., how a system creates an invariant temporal profile against perturbations, is little explored despite transient dynamics being crucial for cellular fates and are reported to be robust experimentally. For example, the duration of a stimulus elicits different phenotypic responses, and signaling networks process and encode temporal information. Hence, robustness in time courses will be necessary for functional biochemical networks. Based on dynamical systems theory, we uncovered a general mechanism to achieve dynamics robustness. Using a three-stage linear signaling cascade as an example, we found that the temporal profiles and response duration post-stimulus is robust to perturbations against certain parameters. Then analyzing the linearized model, we elucidated the criteria of when signaling cascades will display dynamics robustness. We found that changes in the upstream modules are masked in the cascade, and that the response duration is mainly controlled by the rate-limiting module and organization of the cascade's kinetics. Specifically, we found two necessary conditions for dynamics robustness in signaling cascades: 1) Constraint on the rate-limiting process: The phosphatase activity in the perturbed module is not the slowest. 2) Constraints on the initial conditions: The kinase activity needs to be fast enough such that each module is saturated even with fast phosphatase activity and upstream changes are attenuated. We discussed the relevance of such robustness to several biological examples and the validity of the above conditions therein. Given the applicability of dynamics robustness to a variety of systems, it will provide a

  9. A kinetic model-based algorithm to classify NGS short reads by their allele origin.

    PubMed

    Marinoni, Andrea; Rizzo, Ettore; Limongelli, Ivan; Gamba, Paolo; Bellazzi, Riccardo

    2015-02-01

    Genotyping Next Generation Sequencing (NGS) data of a diploid genome aims to assign the zygosity of identified variants through comparison with a reference genome. Current methods typically employ probabilistic models that rely on the pileup of bases at each locus and on a priori knowledge. We present a new algorithm, called Kimimila (KInetic Modeling based on InforMation theory to Infer Labels of Alleles), which is able to assign reads to alleles by using a distance geometry approach and to infer the variant genotypes accurately, without any kind of assumption. The performance of the model has been assessed on simulated and real data of the 1000 Genomes Project and the results have been compared with several commonly used genotyping methods, i.e., GATK, Samtools, VarScan, FreeBayes and Atlas2. Despite our algorithm does not make use of a priori knowledge, the percentage of correctly genotyped variants is comparable to these algorithms. Furthermore, our method allows the user to split the reads pool depending on the inferred allele origin.

  10. The cross-script length effect: further evidence challenging PDP models of reading aloud.

    PubMed

    Rastle, Kathleen; Havelka, Jelena; Wydell, Taeko N; Coltheart, Max; Besner, Derek

    2009-01-01

    The interaction between length and lexical status is one of the key findings used in support of models of reading aloud that postulate a serial process in the orthography-to-phonology translation (B. S. Weekes, 1997). However, proponents of parallel models argue that this effect arises in peripheral visual or articulatory processes. The authors addressed this possibility using the special characteristics of the Serbian and Japanese writing systems. Experiment 1 examined length effects in Serbian when participants were biased to interpret phonologically bivalent stimuli in the alphabet in which they are words or in the alphabet in which they are nonwords (i.e., the visual characteristics of stimuli were held constant across lexical status). Experiment 2 examined length effects in Japanese kana when words were presented in the kana script in which they usually appear or in the script in which they do not normally appear (i.e., the phonological characteristics of stimuli were held constant across lexical status). Results in both cases showed a larger length effect when stimuli were treated as nonwords and thus offered strong support to models of reading aloud that postulate a serial component.

  11. Reading The Sun: A Three Dimensional Visual Model of The Solar Environment During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Carranza-fulmer, T. L.; Moldwin, M.

    2014-12-01

    The sun is a powerful force that has proven to our society that it has a large impact on our lives. Unfortunately, there is still a lack of awareness on how the sun is capable of affecting Earth. The over all idea of "Reading The Sun" installation is to help demonstrate how the sun impacts the Earth, by compiling various data sources from satellites (SOHO, SDO, and STERO) with solar and solar wind models (MAS and ENLIL) to create a comprehensive three dimensional display of the solar environment. It focuses on the current solar maximum of solar cycle 24 and a CME that impacted Earth's magnetic field on February 27, 2014, which triggered geomagnetic storms around the Earth's poles. The CME was an after-effect of a class X4.9 solar flare, which was released from the sun on February 25, 2014. "Reading The Sun" is a 48" x 48" x 48" hanging model of the sun with color coded open opposing magnetic field lines along with various layers of the solar atmosphere, the heliospheric current sheet, and the inner planets. At the center of the xyz axis is the sun with the open magnetic field lines and the heliospheric current sheet permeating inner planetary space. The xyz axes are color coded to represent various types of information with corresponding visual images for the viewer to be able to read the model. Along the z-axis are three colors (yellow, orange, and green) that represent the different layers of the solar atmosphere (photosphere, chromosphere, and corona) that correspond to three satellite images in various spectrums related to a CME and Solar Flare and the xy-plane shows where the inner planets are in relation to the sun. The exhibit in which "Reading The Sun "is being displayed is called, The Rotation of Language at the Wheather Again Gallery in Rockaway, New York. The intent of the exhibit is to both celebrate as well as present a cautionary tale on the ability of human language to spark and ignite the individual and collective imagination towards an experience

  12. A Multiple Deficit Model of Reading Disability and Attention-Deficit/Hyperactivity Disorder: Searching for Shared Cognitive Deficits

    ERIC Educational Resources Information Center

    McGrath, Lauren M.; Pennington, Bruce F.; Shanahan, Michelle A.; Santerre-Lemmon, Laura E.; Barnard, Holly D.; Willcutt, Erik G.; DeFries, John C.; Olson, Richard K.

    2011-01-01

    Background: This study tests a multiple cognitive deficit model of reading disability (RD), attention-deficit/hyperactivity disorder (ADHD), and their comorbidity. Methods: A structural equation model (SEM) of multiple cognitive risk factors and symptom outcome variables was constructed. The model included phonological awareness as a unique…

  13. The Relationship between Delivery Models and the Grade-Level Reading Development of Sixth-Grade English Learners

    ERIC Educational Resources Information Center

    Arnold, Holly Weber

    2013-01-01

    This study examines the relationship between delivery models (the class size reduction model and the sheltered instruction model) and language development levels on the grade-level reading development of sixth-grade English learners (ELs) attending public middle schools in metro Atlanta, Georgia. The instrument used to measure grade-level mastery…

  14. The body size dependence of trophic cascades.

    PubMed

    DeLong, John P; Gilbert, Benjamin; Shurin, Jonathan B; Savage, Van M; Barton, Brandon T; Clements, Christopher F; Dell, Anthony I; Greig, Hamish S; Harley, Christopher D G; Kratina, Pavel; McCann, Kevin S; Tunney, Tyler D; Vasseur, David A; O'Connor, Mary I

    2015-03-01

    Trophic cascades are indirect positive effects of predators on resources via control of intermediate consumers. Larger-bodied predators appear to induce stronger trophic cascades (a greater rebound of resource density toward carrying capacity), but how this happens is unknown because we lack a clear depiction of how the strength of trophic cascades is determined. Using consumer resource models, we first show that the strength of a trophic cascade has an upper limit set by the interaction strength between the basal trophic group and its consumer and that this limit is approached as the interaction strength between the consumer and its predator increases. We then express the strength of a trophic cascade explicitly in terms of predator body size and use two independent parameter sets to calculate how the strength of a trophic cascade depends on predator size. Both parameter sets predict a positive effect of predator size on the strength of a trophic cascade, driven mostly by the body size dependence of the interaction strength between the first two trophic levels. Our results support previous empirical findings and suggest that the loss of larger predators will have greater consequences on trophic control and biomass structure in food webs than the loss of smaller predators.

  15. 5. VIEW OF UPPER AND LOWER CASCADE BRIDGES AND CASCADE ...

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

    5. VIEW OF UPPER AND LOWER CASCADE BRIDGES AND CASCADE CREEK FROM 100 YARDS WEST OF THE ROSTRUM (ROCK FORMATION ON SOUTH SIDE OF MERCED RIVER). HIGHWAY 140 IS AT BOTTOM OF FRAME. HIGHWAY 120, THE BIG OAK FLAT ROAD CROSSES FRAME JUST ABOVE CENTER. - Cascade Creek Bridge, Spanning Cascade Creek on New Big Oak Flat Road, Yosemite Village, Mariposa County, CA

  16. Forecasting Reading Anxiety for Promoting English-Language Reading Performance Based on Reading Annotation Behavior

    ERIC Educational Resources Information Center

    Chen, Chih-Ming; Wang, Jung-Ying; Chen, Yong-Ting; Wu, Jhih-Hao

    2016-01-01

    To reduce effectively the reading anxiety of learners while reading English articles, a C4.5 decision tree, a widely used data mining technique, was used to develop a personalized reading anxiety prediction model (PRAPM) based on individual learners' reading annotation behavior in a collaborative digital reading annotation system (CDRAS). In…

  17. Effects of Differentiated Reading on Elementary Students' Reading Comprehension and Attitudes toward Reading

    ERIC Educational Resources Information Center

    Shaunessy-Dedrick, Elizabeth; Evans, Linda; Ferron, John; Lindo, Myriam

    2015-01-01

    In this investigation, we examined the effects of a differentiated reading approach on fourth grade students' reading comprehension and attitudes toward reading. Eight Title I schools within one urban district were randomly assigned to treatment (Schoolwide Enrichment Model-Reading [SEM-R]) or control (district reading curriculum) conditions.…

  18. Role of Reading Engagement in Mediating Effects of Reading Comprehension Instruction on Reading Outcomes

    ERIC Educational Resources Information Center

    Wigfield, Allan; Guthrie, John T.; Perencevich, Kathleen C.; Taboada, Ana; Klauda, Susan Lutz; McRae, Angela; Barbosa, Pedro

    2008-01-01

    The engagement model of reading development suggests that instruction improves students' reading comprehension to the extent that it increases students' engagement processes in reading. We compared how Concept-Oriented Reading Instruction (CORI) (support for cognitive and motivational processes in reading), strategy instruction (support for…

  19. Author’s response: A universal approach to modeling visual word recognition and reading: not only possible, but also inevitable.

    PubMed

    Frost, Ram

    2012-10-01

    I have argued that orthographic processing cannot be understood and modeled without considering the manner in which orthographic structure represents phonological, semantic, and morphological information in a given writing system. A reading theory, therefore, must be a theory of the interaction of the reader with his/her linguistic environment. This outlines a novel approach to studying and modeling visual word recognition, an approach that focuses on the common cognitive principles involved in processing printed words across different writing systems. These claims were challenged by several commentaries that contested the merits of my general theoretical agenda, the relevance of the evolution of writing systems, and the plausibility of finding commonalities in reading across orthographies. Other commentaries extended the scope of the debate by bringing into the discussion additional perspectives. My response addresses all these issues. By considering the constraints of neurobiology on modeling reading, developmental data, and a large scope of cross-linguistic evidence, I argue that front-end implementations of orthographic processing that do not stem from a comprehensive theory of the complex information conveyed by writing systems do not present a viable approach for understanding reading. The common principles by which writing systems have evolved to represent orthographic, phonological, and semantic information in a language reveal the critical distributional characteristics of orthographic structure that govern reading behavior. Models of reading should thus be learning models, primarily constrained by cross-linguistic developmental evidence that describes how the statistical properties of writing systems shape the characteristics of orthographic processing. When this approach is adopted, a universal model of reading is possible.

  20. Cascading Effects Following Intervention

    PubMed Central

    Patterson, Gerald R.; Forgatch, Marion S.; DeGarmo, David S.

    2010-01-01

    Four different sources for cascade effects were examined using 9-year process and outcome data from a randomized controlled trial (RCT) of a preventive intervention using Parent Management Training – Oregon Model (PMTO™). The social interaction learning (SIL) model of child antisocial behavior serves as one basis for predicting change. A second source addresses the issue of comorbid relationships among clinical diagnoses. The third source, collateral changes, describes events in which changes in one family member correlate with changes in another. The fourth component is based on the long-term effects of reducing coercion and increasing positive interpersonal processes within the family. New findings from the 9-year follow-up show that mothers experienced benefits as measured by standard of living (i.e., income, occupation, education, and financial stress) and frequency of police arrests. It is assumed that PMTO reduces the level of coercion, which sets the stage for a massive increase in positive social interaction. In effect, PMTO alters the family environment and thereby opens doors to healthy new social environments. PMID:20883592

  1. DETAILED COMPARISON BETWEEN PARTON CASCADE AND HADRONIC CASCADE AT SPS AND RHIC.

    SciTech Connect

    NARA,Y.

    1998-10-23

    The authors study the importance of the partonic phase produced in relativistic heavy ion collision by comparing the parton cascade model and the hadronic cascade model. Hadron yield, baryon stopping and transverse momentum distribution are calculated with JAM and discussions are given comparing with VNI. Both of these models give good description of experimental data. They also discuss the strangeness production mechanism and the directed transverse flow.

  2. The improvement of reading skills of L1 and ESL children using a Response to Intervention (RtI) Model.

    PubMed

    Lipka, Orly; Siegel, Linda S

    2010-11-01

    This study examined the development of literacy skills in children in a district that used a Response to Intervention (RTI) model. The district included children whose first language was English and children who were learning English as a second language (ESL). Tasks measuring phonological awareness, lexical access, and syntactic awareness were administered when the children entered school in kindergarten at age 5. Reading, phonological processing, syntactic awareness, memory, and spelling were administered in grade 7. When the children entered school, significant numbers of them were at risk for literacy difficulties. After systematic instruction and annual monitoring of skills, their reading abilities improved to the extent that only a very small percentage had reading difficulties. The results demonstrated that early identification and intervention and frequent monitoring of basic skills can significantly reduce the incidence of reading problems in both the ESL and language majority children.

  3. Reading(s).

    ERIC Educational Resources Information Center

    Summerfield, Geoffrey; Summerfield, Judith

    Developed for college English courses, this book presents selections of poetry, short stories, and commentary intended to invite different ways of reading and interpreting literature. An introduction provides an overview of the book's content, as well as a discussion of how to read. The first section, "Entering a Language," considers the…

  4. Modeling the Length Effect: Specifying the Relation with Visual and Phonological Correlates of Reading

    ERIC Educational Resources Information Center

    van den Boer, Madelon; de Jong, Peter F.; Haentjens-van Meeteren, Marleen M.

    2013-01-01

    Beginning readers' reading latencies increase as words become longer. This length effect is believed to be a marker of a serial reading process. We examined the effects of visual and phonological skills on the length effect. Participants were 184 second-grade children who read 3- to 5-letter words and nonwords. Results indicated that reading…

  5. Modeling Local Item Dependence in Cloze and Reading Comprehension Test Items Using Testlet Response Theory

    ERIC Educational Resources Information Center

    Baghaei, Purya; Ravand, Hamdollah

    2016-01-01

    In this study the magnitudes of local dependence generated by cloze test items and reading comprehension items were compared and their impact on parameter estimates and test precision was investigated. An advanced English as a foreign language reading comprehension test containing three reading passages and a cloze test was analyzed with a…

  6. Using Multilevel Modeling for Change to Assess Early Children's Reading Growth over Time

    ERIC Educational Resources Information Center

    Liu, Xing; O'Connell, Ann A.

    2008-01-01

    Childhood is the crucial period for early children's reading ability building. Former research (Hanson & Farrell, 1995) found that early reading experience had a positive and long-term effect on reading competence for high school seniors in the future. Therefore, it is of great importance for researchers to understand children's initial reading…

  7. A Data-Driven Coaching Model Used to Promote Students' Response to Early Reading Intervention

    ERIC Educational Resources Information Center

    Glover, Todd A.

    2017-01-01

    Given the importance of early reading performance as a foundational prerequisite for student achievement, schools have allocated significant attention over the past decade to training teachers to assess and monitor students' reading progress and to implement instruction or interventions targeting early reading skills (e.g., Fletcher & Vaughn,…

  8. Metrological Traceability in the Social Sciences: A Model from Reading Measurement

    NASA Astrophysics Data System (ADS)

    Stenner, A. Jackson; Fisher, William P., Jr.

    2013-09-01

    The central importance of reading ability in learning makes it the natural place to start in formative and summative assessments in education. The Lexile Framework for Reading constitutes a commercial metrological traceability network linking books, test results, instructional materials, and students in elementary and secondary English and Spanish language reading education in the U.S., Canada, Mexico, and Australia.

  9. Towards a Dynamic Model of Skills Involved in Sight Reading Music

    ERIC Educational Resources Information Center

    Kopiez, Reinhard; Lee, Ji In

    2006-01-01

    This study investigates the relationship between selected predictors of achievement in playing unrehearsed music (sight reading) and the changing complexity of sight reading tasks. The question under investigation is, how different variables gain or lose significance as sight reading stimuli become more difficult. Fifty-two piano major graduates…

  10. The Relation between Morphological Awareness and Reading Comprehension: Evidence from Mediation and Longitudinal Models

    ERIC Educational Resources Information Center

    Deacon, S. Hélène; Kieffer, Michael J.; Laroche, Annie

    2014-01-01

    We examined the role of a hypothesized factor in reading comprehension: morphological awareness, or the awareness of and ability to manipulate the smallest meaningful units or morphemes. In this longitudinal study, we measured English-speaking children's morphological awareness, word reading skills, and reading comprehension at Grades 3 and 4, in…

  11. The Collaboration Model and Reading Improvement of High School Students with Learning Disabilities

    ERIC Educational Resources Information Center

    Sacchetto, Jorge A.

    2014-01-01

    In the field of reading research, studies focusing on improvement of a high school student's reading achievements are lacking. Collaborative interventions for reading instruction are useful and more prevalent for elementary age students but not high school students. Therefore, there remains an important gap in the current literature regarding…

  12. The Collaboration Model and Reading Improvement of High School Students with Learning Disabilities

    ERIC Educational Resources Information Center

    Sacchetto, Jorge A.

    2014-01-01

    In the field of reading research, studies that focus on improving the reading achievement of high school students with learning disabilities are lacking. Although collaborative interventions for elementary age students have been shown to be effective, a gap exists in the current research regarding effective collaborative reading interventions for…

  13. A Biologically Realistic Cortical Model of Eye Movement Control in Reading

    ERIC Educational Resources Information Center

    Heinzle, Jakob; Hepp, Klaus; Martin, Kevan A. C.

    2010-01-01

    Reading is a highly complex task involving a precise integration of vision, attention, saccadic eye movements, and high-level language processing. Although there is a long history of psychological research in reading, it is only recently that imaging studies have identified some neural correlates of reading. Thus, the underlying neural mechanisms…

  14. Reading Logs and Literature Teaching Models in English Language Teacher Education

    ERIC Educational Resources Information Center

    Ochoa Delarriva, Ornella; Basabe, Enrique Alejandro

    2016-01-01

    Reading logs are regularly used in foreign language education since they are not only critical in the development of reading comprehension but may also be instrumental in taking readers beyond the referential into the representational realms of language. In this paper we offer the results of a qualitative analysis of a series of reading logs…

  15. Tone matters for Cantonese-English bilingual children's English word reading development: A unified model of phonological transfer.

    PubMed

    Tong, Xiuli; He, Xinjie; Deacon, S Hélène

    2017-02-01

    Languages differ considerably in how they use prosodic features, or variations in pitch, duration, and intensity, to distinguish one word from another. Prosodic features include lexical tone in Chinese and lexical stress in English. Recent cross-sectional studies show a surprising result that Mandarin Chinese tone sensitivity is related to Mandarin-English bilingual children's English word reading. This study explores the mechanism underlying this relation by testing two explanations of these effects: the prosodic hypothesis and segmental phonological awareness transfer. We administered multiple measures of Cantonese tone sensitivity, English stress sensitivity, segmental phonological awareness in Cantonese and English, nonverbal ability, and English word reading to 123 Cantonese-English bilingual children ages 7 and 8 years. Structural equation modeling revealed a longitudinal prediction of Cantonese tone sensitivity to English word reading between 8 and 9 years of age. This relation was realized through two parallel routes. In one, Cantonese tone sensitivity predicted English stress sensitivity, and English stress sensitivity, in turn, significantly predicted English word reading, as postulated by the prosodic hypothesis. In the second, Cantonese tone sensitivity predicted English word reading through the transfer of segmental phonological awareness between Cantonese and English, as predicted by segmental phonological transfer. These results support a unified model of phonological transfer, emphasizing the role of tone in English word reading for Cantonese-English bilingual children.

  16. The nitrogen cascade

    SciTech Connect

    Galloway J.N.; Aber J.D.; Erisman J.W.; Seitzinger S.P.; Howarth R.W.; Cowling E.B.; Cosby B.J.

    2003-04-01

    Human production of food and energy is the dominant continental process that breaks the triple bond in molecular nitrogen (N{sub 2}) and creates reactive nitrogen (Nr) species. Circulation of anthropogenic Nr in Earth's atmosphere, hydrosphere, and biosphere has a wide variety of consequences, which are magnified with time as Nr moves along its biogeochemical pathway. The same atom of Nr can cause multiple effects in the atmosphere, in terrestrial ecosystems, in freshwater and marine systems, and on human health. We call this sequence of effects the nitrogen cascade. As the cascade progresses, the origin of Nr becomes unimportant. Reactive nitrogen does not cascade at the same rate through all environmental systems; some systems have the ability to accumulate Nr, which leads to lag times in the continuation of the cascade. These lags slow the cascade and result in Nr accumulation in certain reservoirs, which in turn can enhance the effects of Nr on that environment. The only way to eliminate Nr accumulation and stop the cascade is to convert Nr back to nonreactive N{sub 2}.

  17. Reading as active sensing: a computational model of gaze planning in word recognition.

    PubMed

    Ferro, Marcello; Ognibene, Dimitri; Pezzulo, Giovanni; Pirrelli, Vito

    2010-01-01

    WE OFFER A COMPUTATIONAL MODEL OF GAZE PLANNING DURING READING THAT CONSISTS OF TWO MAIN COMPONENTS: a lexical representation network, acquiring lexical representations from input texts (a subset of the Italian CHILDES database), and a gaze planner, designed to recognize written words by mapping strings of characters onto lexical representations. The model implements an active sensing strategy that selects which characters of the input string are to be fixated, depending on the predictions dynamically made by the lexical representation network. We analyze the developmental trajectory of the system in performing the word recognition task as a function of both increasing lexical competence, and correspondingly increasing lexical prediction ability. We conclude by discussing how our approach can be scaled up in the context of an active sensing strategy applied to a robotic setting.

  18. Reading as Active Sensing: A Computational Model of Gaze Planning in Word Recognition

    PubMed Central

    Ferro, Marcello; Ognibene, Dimitri; Pezzulo, Giovanni; Pirrelli, Vito

    2010-01-01

    We offer a computational model of gaze planning during reading that consists of two main components: a lexical representation network, acquiring lexical representations from input texts (a subset of the Italian CHILDES database), and a gaze planner, designed to recognize written words by mapping strings of characters onto lexical representations. The model implements an active sensing strategy that selects which characters of the input string are to be fixated, depending on the predictions dynamically made by the lexical representation network. We analyze the developmental trajectory of the system in performing the word recognition task as a function of both increasing lexical competence, and correspondingly increasing lexical prediction ability. We conclude by discussing how our approach can be scaled up in the context of an active sensing strategy applied to a robotic setting. PMID:20577589

  19. Reading Ability Development from Kindergarten to Junior Secondary: Latent Transition Analyses with Growth Mixture Modeling

    PubMed Central

    Liu, Yuan; Liu, Hongyun; Hau, Kit-tai

    2016-01-01

    The present study examined the reading ability development of children in the large scale Early Childhood Longitudinal Study (Kindergarten Class of 1998-99 data; Tourangeau et al., 2009) under the dynamic systems. To depict children's growth pattern, we extended the measurement part of latent transition analysis to the growth mixture model and found that the new model fitted the data well. Results also revealed that most of the children stayed in the same ability group with few cross-level changes in their classes. After adding the environmental factors as predictors, analyses showed that children receiving higher teachers' ratings, with higher socioeconomic status, and of above average poverty status, would have higher probability to transit into the higher ability group. PMID:27826278

  20. Cascading failure in the wireless sensor scale-free networks

    NASA Astrophysics Data System (ADS)

    Liu, Hao-Ran; Dong, Ming-Ru; Yin, Rong-Rong; Han, Li

    2015-05-01

    In the practical wireless sensor networks (WSNs), the cascading failure caused by a failure node has serious impact on the network performance. In this paper, we deeply research the cascading failure of scale-free topology in WSNs. Firstly, a cascading failure model for scale-free topology in WSNs is studied. Through analyzing the influence of the node load on cascading failure, the critical load triggering large-scale cascading failure is obtained. Then based on the critical load, a control method for cascading failure is presented. In addition, the simulation experiments are performed to validate the effectiveness of the control method. The results show that the control method can effectively prevent cascading failure. Project supported by the Natural Science Foundation of Hebei Province, China (Grant No. F2014203239), the Autonomous Research Fund of Young Teacher in Yanshan University (Grant No. 14LGB017) and Yanshan University Doctoral Foundation, China (Grant No. B867).

  1. Reading, Perceptual Strategies and Contrastive Analysis

    ERIC Educational Resources Information Center

    Cowan, J. Ronayne

    1976-01-01

    Analyzes syntactic processes in three learning situations, Japanese reading English, Persians reading English and English speakers reading Hindi; discussed in terms of reading process and second language learning models. (Author/RM)

  2. Reading Ourselves.

    ERIC Educational Resources Information Center

    Sherriff, Dawn

    2001-01-01

    Describes how reading and art have taught the author to slow down. Discusses how she wants her students to leave the third-grade classroom reading--reading words, reading pictures, and reading their world. Considers how one student slows down her reading, pays attention to her thinking, and begins to see the pictures and connections that poems…

  3. REMEDIATING READING DIFFICULTIES IN A RESPONSE TO INTERVENTION MODEL WITH SECONDARY STUDENTS

    PubMed Central

    PYLE, NICOLE; VAUGHN, SHARON

    2012-01-01

    The research on Response to Intervention (RtI) with secondary students is scant; however, a recently conducted, multiyear, large-scale implementation of RtI with middle-school students provides findings that inform practices and future directions for research. This article provides an overview of the findings from each of the 3 years of an intensive, tiered reading intervention with middle-school students. In Year 1, students were provided with a Tier 1 and Tier 2 intervention. In Year 2, minimal responders were provided with another year of intervention (Tier 3), and again in Year 3, minimal responders to the 2-year intervention were provided with a third year of intervention (Tier 4). Using students’ responsiveness to intervention as a prerequisite for a subsequent year of intensive instruction, minimal responders received a total of up to 3 years of intervention. The efficacy of an enhanced primary (Tier 1), secondary (Tier 2), and tertiary (Tier 3) intervention, and an individualized, intensive reading intervention (Tier 4) are discussed, as well as the logistics of implementing an RtI model with secondary students. PMID:23100631

  4. Secondary factors influencing cascade damage formation

    NASA Astrophysics Data System (ADS)

    Stoller, Roger E.; Guiriec, Sylvain G.

    2004-08-01

    Primary cascade damage production in iron has been extensively investigated by molecular dynamics, and the average defect production as a function of cascade energy and temperature is well characterized. However, preliminary results indicate several factors alter `normal' cascade evolution, leading to quite different defect production behavior. Further investigation of three such factors has been carried out: (1) primary knock-on atom (PKA) direction, (2) nearby free surfaces, and (3) pre-existing effects. Results of the investigation confirm these factors significantly impact damage production. Effects include: enhanced defect survival for PKA directions lying in close-packed {1 1 0} planes, increased point defect clustering and larger defect clusters in cascades initiated near a surface, and reduced defect survival in material containing defects. The origin and implications of these effects are discussed relative to the interpretation of certain experimental observations and parameters used in other modeling studies.

  5. Experimental and modeling study of off-beam quartz-enhanced photoacoustic detection of nitrogen monoxide (NO) using a quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Shi, Chao; Li, Zhili; Ren, Wei

    2016-11-01

    This article presents the experimental and modeling study of quartz-enhanced photoacoustic detection of nitrogen monoxide (NO) using the off-beam configuration and a distributed-feedback (DFB) quantum cascade laser (QCL) at 5.26 μm as the excitation source. Trace gas monitoring of NO is one of the important subjects for both environmental protection and human health monitoring. Quartz-enhanced photoacoustic spectroscopy (QEPAS) with on-beam configuration is mostly adopted for gas detection. In comparison, the off-beam approach has not only comparative detection sensitivity but also significant advantage of simpler installation and optical alignment. We optimized the sensor performance by adjusting the horizontal and vertical distances between the micro-resonator (mR) and the QTF prongs. Pressure and humidity are two important factors affecting the photoacoustic signal. The effects of both parameters on the NO concentration determination were investigated.

  6. The Impact of the Brazosport Model on English Language Learners' Reading Achievement in Grades 3-5

    ERIC Educational Resources Information Center

    Garcia, Debra Ann N.

    2012-01-01

    The general purpose of this study was to determine if the implementation of the Brazosport Model improves student reading achievement as determined by Arizona's Instrument to Measure Standards (AIMS). In particular, this study examined the implementation of the Brazosport Model and its effect on the achievement of English Language Learners (ELLs)…

  7. Modeling Polymorphemic Word Recognition: Exploring Differences among Children with Early-Emerging and Late- Emerging Word Reading Difficulty

    ERIC Educational Resources Information Center

    Kearns, Devin M.; Steacy, Laura M.; Compton, Donald L.; Gilbert, Jennifer K.; Goodwin, Amanda P.; Cho, Eunsoo; Lindstrom, Esther R.; Collins, Alyson A.

    2016-01-01

    Comprehensive models of derived polymorphemic word recognition skill in developing readers, with an emphasis on children with reading difficulty (RD), have not been developed. The purpose of the present study was to model individual differences in polymorphemic word recognition ability at the item level among 5th-grade children (N = 173)…

  8. Simulating Language-Specific and Language-General Effects in a Statistical Learning Model of Chinese Reading

    ERIC Educational Resources Information Center

    Yang, Jianfeng; McCandliss, Bruce D.; Shu, Hua; Zevin, Jason D.

    2009-01-01

    Many theoretical models of reading assume that different writing systems require different processing assumptions. For example, it is often claimed that print-to-sound mappings in Chinese are not represented or processed sub-lexically. We present a connectionist model that learns the print-to-sound mappings of Chinese characters using the same…

  9. Examining the Relationship between Middle School Students' Critical Reading Skills, Science Literacy Skills and Attitudes: A Structural Equation Modeling

    ERIC Educational Resources Information Center

    Karademir, Ersin; Ulucinar, Ufuk

    2017-01-01

    The purpose of this study is to verify the causal relationship between middle school students' critical reading skills, science literacy skills and attitudes towards science literacy with research data according to the default model. Through the structural equation modeling, path analysis has been applied in the study which was designed in…

  10. The nitrogen cascade from agricultural soils to the sea: modelling nitrogen transfers at regional watershed and global scales.

    PubMed

    Billen, Gilles; Garnier, Josette; Lassaletta, Luis

    2013-07-05

    The nitrogen cycle of pre-industrial ecosystems has long been remarkably closed, in spite of the high mobility of this element in the atmosphere and hydrosphere. Inter-regional and international commercial exchanges of agricultural goods, which considerably increased after the generalization of the use of synthetic nitrogen fertilizers, introduced an additional type of nitrogen mobility, which nowadays rivals the atmospheric and hydrological fluxes in intensity, and causes their enhancement at the local, regional and global scales. Eighty-five per cent of the net anthropogenic input of reactive nitrogen occurs on only 43 per cent of the land area. Modern agriculture based on the use of synthetic fertilizers and the decoupling of crop and animal production is responsible for the largest part of anthropogenic losses of reactive nitrogen to the environment. In terms of levers for better managing the nitrogen cascade, beyond technical improvement of agricultural practices tending to increase nitrogen use efficiency, or environmental engineering management measures to increase nitrogen sinks in the landscape, the need to better localize crop production and livestock breeding, on the one hand, and agriculture and food demand on the other hand, is put forward as a condition to being able to supply food to human populations while preserving environmental resources.

  11. The nitrogen cascade from agricultural soils to the sea: modelling nitrogen transfers at regional watershed and global scales

    PubMed Central

    Billen, Gilles; Garnier, Josette; Lassaletta, Luis

    2013-01-01

    The nitrogen cycle of pre-industrial ecosystems has long been remarkably closed, in spite of the high mobility of this element in the atmosphere and hydrosphere. Inter-regional and international commercial exchanges of agricultural goods, which considerably increased after the generalization of the use of synthetic nitrogen fertilizers, introduced an additional type of nitrogen mobility, which nowadays rivals the atmospheric and hydrological fluxes in intensity, and causes their enhancement at the local, regional and global scales. Eighty-five per cent of the net anthropogenic input of reactive nitrogen occurs on only 43 per cent of the land area. Modern agriculture based on the use of synthetic fertilizers and the decoupling of crop and animal production is responsible for the largest part of anthropogenic losses of reactive nitrogen to the environment. In terms of levers for better managing the nitrogen cascade, beyond technical improvement of agricultural practices tending to increase nitrogen use efficiency, or environmental engineering management measures to increase nitrogen sinks in the landscape, the need to better localize crop production and livestock breeding, on the one hand, and agriculture and food demand on the other hand, is put forward as a condition to being able to supply food to human populations while preserving environmental resources. PMID:23713121

  12. Effects of a randomised reading intervention study: an application of structural equation modelling.

    PubMed

    Wolff, Ulrika

    2011-11-01

    An intensive phonics-based intervention program for nine-year-old Swedish pupils with reading difficulties was performed. Pupils (N = 112) were randomly assigned to either an intervention or a control group. The training was tailored to the Swedish transparent orthography and designed for one-to-one-tutoring during twelve weeks. Previously, reading speed has been shown to be hard to remediate, and one important purpose was to improve reading speed by explicit training. The intervention group showed improvements immediately after intervention in spelling, reading comprehension, reading speed, and phoneme awareness. There were also significant indirect effects from intervention to all variables one year later. Reading comprehension at immediate post-test predicted spelling one year later, and phoneme awareness at post-test predicted both spelling and reading comprehension one year later. The results suggest the importance of a multi-component intervention, even in transparent orthographies, which includes phonics combined with comprehension strategies and fluency training.

  13. iCRESLIDE: Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium for the Cascading Hydrologic-Geotechnical Modeling

    NASA Astrophysics Data System (ADS)

    Hong, Y.; Zhang, K.; Gourley, J. J.

    2015-12-01

    Floods and landslides account for the large number of natural hazards and affect more people than many other types of natural disasters around the world. This study proposed a coupled hydrological-geotechnical model iCRESLIDE (Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium). The iCRESLIDE is designed to remedy the discrepancy of the original landslide model (SLIDE) by coupling with a hydrological model (CREST) and building an integrated system for predicting cascading storm-flood-landslides using remote sensing and geospatial datasets. This coupled system is implemented and evaluated in Macon County, North Carolina, where Hurricane Ivan triggered widespread landslides in September 2004 during the hurricane season. Model simulations from iCRESLIDE show its reliability to predict landslides occurrence (location and time). Receiver Operating Characteristic (ROC) analysis demonstrate that the iCRESLIDE has higher global accuracy (0.750) and higher sensitivity (11.36%) compared to the original SLIDE model. Such improved predictive performance demonstrates the advantage of coupling hydrological-geotechnical models, which calls more attentions and deserves further investigations in order to develop a not only geotechnical sound but also hydrological sensitive system for landslides early warning at regional scale. This talk will also present early results of the NFL (National-Flash-Landslide) Monitoring and Prediction system under development at the NOAA/OU National Weather Center.

  14. Extension of the Liège Intra Nuclear Cascade model to light ion-induced collisions for medical and space applications

    NASA Astrophysics Data System (ADS)

    Leray, S.; Mancusi, D.; Kaitaniemi, P.; David, J. C.; Boudard, A.; Braunn, B.; Cugnon, J.

    2013-03-01

    The Liège Intranuclear Cascade model, INCL4, has been developed to describe spallation reactions, i.e. nucleon and light charged particle induced collisions in the 100 MeV - 3 GeV energy range. Extensive comparisons with experimental data covering all possible reaction channels have shown that, coupled to the ABLA07 de-excitation code from GSI, it is presently one of the most reliable models in its domain. Recently, the treatment of composite particle as projectlies has been revisited mainly to improve predictions related to secondary reactions in spallation targets. An example regarding astatine production in LBE targets will be shown. Also, the model has been extended to light ion (up to oxygen) induced reactions, mostly for medical and space application purposes. This version is available in GEANT4. The first results indicate that the model agrees at least as well as other models with experimental data. In this paper, the different assumptions and ingredients of the model will be presented and comparisons with relevant experimental data will be shown. The sensitivity to the de-excitation stage is also discussed.

  15. Turbulence: Does Energy Cascade Exist?

    NASA Astrophysics Data System (ADS)

    Josserand, Christophe; Le Berre, Martine; Lehner, Thierry; Pomeau, Yves

    2016-11-01

    To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These tests are applied to real Eulerian data of a turbulent velocity flow, taken in the wind grid tunnel of Modane, and also to a prototype model equation for wave turbulence. First we demonstrate the irreversible character of the flow by using multi-time correlation function at a given point of space. Moreover the unexpected behavior of the test function leads us to connect irreversibility and finite time singularities (intermittency). Secondly we show that turbulent cascade exists, and is a dynamical process, by using a test function depending on time and frequency. The cascade shows up only in the inertial domain where the kinetic energy is transferred more rapidly (on average) from the wavenumber k1 to k2 than from k1 to k'2 larger than k2.

  16. Demixing cascades in cluster crystals.

    PubMed

    Wilding, Nigel B; Sollich, Peter

    2014-09-07

    In a cluster crystal, each lattice site is occupied by multiple soft-core particles. As the number density is increased at zero temperature, a "cascade" of isostructural phase transitions can occur between states whose site occupancy differs by unity. For low but finite temperature, each of these transitions terminates in a critical point. Using tailored Monte Carlo simulation techniques, we have studied such demixing cascades in systems of soft particles interacting via potentials of the generalized exponential form u(r) = ε exp [-(r/σ)(n)]. We have estimated the critical parameters of the first few transitions in the cascade as a function of the softness parameter n. The critical temperature and pressure exhibit non-monotonic behavior as n is varied, although the critical chemical potential remains monotonic. The trends for the pressure and chemical potential are confirmed by cell model calculations at zero temperature. As n → 2(+), all the transitions that we have observed are preempted by melting although we cannot rule out that clustering transitions survive at high density.

  17. Dynamics robustness of cascading systems

    PubMed Central

    Kaneko, Kunihiko

    2017-01-01

    A most important property of biochemical systems is robustness. Static robustness, e.g., homeostasis, is the insensitivity of a state against perturbations, whereas dynamics robustness, e.g., homeorhesis, is the insensitivity of a dynamic process. In contrast to the extensively studied static robustness, dynamics robustness, i.e., how a system creates an invariant temporal profile against perturbations, is little explored despite transient dynamics being crucial for cellular fates and are reported to be robust experimentally. For example, the duration of a stimulus elicits different phenotypic responses, and signaling networks process and encode temporal information. Hence, robustness in time courses will be necessary for functional biochemical networks. Based on dynamical systems theory, we uncovered a general mechanism to achieve dynamics robustness. Using a three-stage linear signaling cascade as an example, we found that the temporal profiles and response duration post-stimulus is robust to perturbations against certain parameters. Then analyzing the linearized model, we elucidated the criteria of when signaling cascades will display dynamics robustness. We found that changes in the upstream modules are masked in the cascade, and that the response duration is mainly controlled by the rate-limiting module and organization of the cascade’s kinetics. Specifically, we found two necessary conditions for dynamics robustness in signaling cascades: 1) Constraint on the rate-limiting process: The phosphatase activity in the perturbed module is not the slowest. 2) Constraints on the initial conditions: The kinase activity needs to be fast enough such that each module is saturated even with fast phosphatase activity and upstream changes are attenuated. We discussed the relevance of such robustness to several biological examples and the validity of the above conditions therein. Given the applicability of dynamics robustness to a variety of systems, it will provide a

  18. Changes in reading strategies in school-age children.

    PubMed

    Sanabria Díaz, Gretel; Torres, María del Rosario; Iglesias, Jorge; Mosquera, Raysil; Reigosa, Vivian; Santos, Elsa; Lage, Agustín; Estévez, Nancy; Galán, Lidice

    2009-11-01

    Learning to read is one of the most important cognitive milestones in the human social environment. One of the most accepted models explaining such process is the Double-Route Cascaded Model. It suggests the existence of two reading strategies: lexical and sublexical. In the Spanish language there are some contradictions about how these strategies are applied for reading. In addition, there are only a few studies dealing with the analysis of shifts between them, achieving a fluent reading process. In this paper we use a reading task including words and pseudowords for characterizing the cost of shifting between reading strategies in children with developmental dyslexia and normal controls. Our results suggest the presence of both strategies in these two experimental groups. In controls, both strategies become more efficient in correspondence to the increased exposition to written material. However, in children with developmental dyslexia only the lexical strategy exhibits such improvement. Their also point to a low cost for shifting between strategies in controls and a much more significant one in children with developmental dyslexia, differentiating subgroups with distinct shifting patterns.

  19. geant4 hadronic cascade models analysis of proton and charged pion transverse momentum spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c

    SciTech Connect

    Abdel-Waged, Khaled; Felemban, Nuha; Uzhinskii, V. V.

    2011-07-15

    We describe how various hadronic cascade models, which are implemented in the geant4 toolkit, describe proton and charged pion transverse momentum spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c, recently measured in the hadron production (HARP) experiment at CERN. The Binary, ultrarelativistic quantum molecular dynamics (UrQMD) and modified FRITIOF (FTF) hadronic cascade models are chosen for investigation. The first two models are based on limited (Binary) and branched (UrQMD) binary scattering between cascade particles which can be either a baryon or meson, in the three-dimensional space of the nucleus, while the latter (FTF) considers collective interactions between nucleons only, on the plane of impact parameter. It is found that the slow (p{sub T}{<=}0.3 GeV/c) proton spectra are quite sensitive to the different treatments of cascade pictures, while the fast (p{sub T}>0.3 GeV/c) proton spectra are not strongly affected by the differences between the FTF and UrQMD models. It is also shown that the UrQMD and FTF combined with Binary (FTFB) models could reproduce both proton and charged pion spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c with the same accuracy.

  20. Computer modeling and design of diagnostic workstations and radiology reading rooms

    NASA Astrophysics Data System (ADS)

    Ratib, Osman M.; Amato, Carlos L.; Balbona, Joseph A.; Boots, Kevin; Valentino, Daniel J.

    2000-05-01

    We used 3D modeling techniques to design and evaluate the ergonomics of diagnostic workstation and radiology reading room in the planning phase of building a new hospital at UCLA. Given serious space limitations, the challenge was to provide more optimal working environment for radiologists in a crowded and busy environment. A particular attention was given to flexibility, lighting condition and noise reduction in rooms shared by multiple users performing diagnostic tasks as well as regular clinical conferences. Re-engineering workspace ergonomics rely on the integration of new technologies, custom designed cabinets, indirect lighting, sound-absorbent partitioning and geometric arrangement of workstations to allow better privacy while optimizing space occupation. Innovations included adjustable flat monitors, integration of videoconferencing and voice recognition, control monitor and retractable keyboard for optimal space utilization. An overhead compartment protecting the monitors from ambient light is also used as accessory lightbox and rear-view projection screen for conferences.

  1. Reading Aloud: Discrete Stage(s) Redux

    PubMed Central

    Robidoux, Serje; Besner, Derek

    2017-01-01

    Interactive activation accounts of processing have had a broad and deep influence on cognitive psychology, particularly so in the context of computational accounts of reading aloud at the single word level. Here we address the issue of whether such a framework can simulate the joint effects of stimulus quality and word frequency (which have been shown to produce both additive and interactive effects depending on the context). We extend previous work on this question by considering an alternative implementation of a stimulus quality manipulation, and the role of interactive activation. Simulations with a version of the Dual Route Cascaded model (a model with interactive activation dynamics along the lexical route) demonstrate that the model is unable to simulate the entire pattern seen in human performance. We discuss how a hybrid interactive activation model that includes some context dependent staged processing could accommodate these data. PMID:28289395

  2. Tracking Earthquake Cascades

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.

    2011-12-01

    In assessing their risk to society, earthquakes are best characterized as cascades that can propagate from the natural environment into the socio-economic (built) environment. Strong earthquakes rarely occur as isolated events; they usually cluster in foreshock-mainshock-aftershock sequences, seismic swarms, and extended sequences of large earthquakes that propagate along major fault systems. These cascades are regulated by stress-mediated interactions among faults driven by tectonic loading. Within these cascades, each large event can itself cause a chain reaction in which the primary effects of faulting and ground shaking induce secondary effects, including tsunami, landslides, liquefaction, and set off destructive processes within the built environment, such as fires and radiation leakage from nuclear plants. Recent earthquakes have demonstrated how the socio-economic effects of large earthquakes can reverberate for many years. To reduce earthquake risk and improve the resiliency of communities to earthquake damage, society depends on five geotechnologies for tracking earthquake cascades: long-term probabilistic seismic hazard analysis (PSHA), short-term (operational) earthquake forecasting, earthquake early warning, tsunami warning, and the rapid production of post-event information for response and recovery (see figure). In this presentation, I describe how recent advances in earthquake system science are leading to improvements in this geotechnology pipeline. In particular, I will highlight the role of earthquake simulations in predicting strong ground motions and their secondary effects before and during earthquake cascades

  3. Engaging the Entire Care Cascade in Western Kenya: A Model to Achieve the Cardiovascular Disease Secondary Prevention Roadmap Goals.

    PubMed

    Vedanthan, Rajesh; Kamano, Jemima H; Bloomfield, Gerald S; Manji, Imran; Pastakia, Sonak; Kimaiyo, Sylvester N

    2015-12-01

    Cardiovascular disease (CVD) is the leading cause of death in the world, with a substantial health and economic burden confronted by low- and middle-income countries. In low-income countries such as Kenya, there exists a double burden of communicable and noncommunicable diseases, and the CVD profile includes many nonatherosclerotic entities. Socio-politico-economic realities present challenges to CVD prevention in Kenya, including poverty, low national spending on health, significant out-of-pocket health expenditures, and limited outpatient health insurance. In addition, the health infrastructure is characterized by insufficient human resources for health, medication stock-outs, and lack of facilities and equipment. Within this socio-politico-economic reality, contextually appropriate programs for CVD prevention need to be developed. We describe our experience from western Kenya, where we have engaged the entire care cascade across all levels of the health system, in order to improve access to high-quality, comprehensive, coordinated, and sustainable care for CVD and CVD risk factors. We report on several initiatives: 1) population-wide screening for hypertension and diabetes; 2) engagement of community resources and governance structures; 3) geographic decentralization of care services; 4) task redistribution to more efficiently use of available human resources for health; 5) ensuring a consistent supply of essential medicines; 6) improving physical infrastructure of rural health facilities; 7) developing an integrated health record; and 8) mobile health (mHealth) initiatives to provide clinical decision support and record-keeping functions. Although several challenges remain, there currently exists a critical window of opportunity to establish systems of care and prevention that can alter the trajectory of CVD in low-resource settings.

  4. Modeled and measured glacier change and related glaciological, hydrological, and meteorological conditions at South Cascade Glacier, Washington, balance and water years 2006 and 2007

    USGS Publications Warehouse

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2010-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance years 2006 and 2007. Mass balances were computed with assistance from a new model that was based on the works of other glacier researchers. The model, which was developed for mass balance practitioners, coupled selected meteorological and glaciological data to systematically estimate daily mass balance at selected glacier sites. The North Cascade Range in the vicinity of South Cascade Glacier accumulated approximately average to above average winter snow packs during 2006 and 2007. Correspondingly, the balance years 2006 and 2007 maximum winter snow mass balances of South Cascade Glacier, 2.61 and 3.41 meters water equivalent, respectively, were approximately equal to or more positive (larger) than the average of such balances since 1959. The 2006 glacier summer balance, -4.20 meters water equivalent, was among the four most negative since 1959. The 2007 glacier summer balance, -3.63 meters water equivalent, was among the 14 most negative since 1959. The glacier continued to lose mass during 2006 and 2007, as it commonly has since 1953, but the loss was much smaller during 2007 than during 2006. The 2006 glacier net balance, -1.59 meters water equivalent, was 1.02 meters water equivalent more negative (smaller) than the average during 1953-2005. The 2007 glacier net balance, -0.22 meters water equivalent, was 0.37 meters water equivalent less negative (larger) than the average during 1953-2006. The 2006 accumulation area ratio was less than 0.10, owing to isolated patches of accumulated snow that endured the 2006 summer season. The 2006 equilibrium line altitude was higher than the glacier. The 2007 accumulation area ratio and equilibrium line altitude were 0.60 and 1,880 meters, respectively. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The

  5. Survey of tools for risk assessment of cascading outages

    SciTech Connect

    Papic, Milorad; Bell, Keith; Chen, Yousu; Dobson, Ian; Fonte, Louis; Haq, Enamul; Hines, Paul; Kirschen, Daniel; Luo, Xiaochuan; Miller, Stephen; Samaan, Nader A.; Vaiman, Marianna; Varghese, Matthew; Zhang, Pei

    2011-10-01

    Abstract-This paper is a result of ongoing activity carried out by Understanding, Prediction, Mitigation and Restoration of Cascading Failures Task Force under IEEE Computer Analytical Methods Subcommittee (CAMS). The task force's previous papers [1, 2] are focused on general aspects of cascading outages such as understanding, prediction, prevention and restoration from cascading failures. This is the second of two new papers, which extend this previous work to summarize the state of the art in cascading failure risk analysis methodologies and modeling tools. The first paper reviews the state of the art in methodologies for performing risk assessment of potential cascading outages [3]. This paper describes the state of the art in cascading failure modeling tools, documenting the view of experts representing utilities, universities and consulting companies. The paper is intended to constitute a valid source of information and references about presently available tools that deal with prediction of cascading failure events. This effort involves reviewing published literature and other documentation from vendors, universities and research institutions. The assessment of cascading outages risk evaluation is in continuous evolution. Investigations to gain even better understanding and identification of cascading events are the subject of several research programs underway aimed at solving the complexity of these events that electrical utilities face today. Assessing the risk of cascading failure events in planning and operation for power transmission systems require adequate mathematical tools/software.

  6. Rehmannia Glutinosa Extract Activates Endothelial Progenitor Cells in a Rat Model of Myocardial Infarction through a SDF-1 α/CXCR4 Cascade

    PubMed Central

    Wang, Ying-Bin; Liu, Yun-Fang; Lu, Xiao-Ting; Yan, Fang-Fang; Wang, Bo; Bai, Wen-Wu; Zhao, Yu-Xia

    2013-01-01

    Objectives Endothelial progenitor cells (EPCs) can be used to repair tissues after myocardial infarction (MI) but EPC activators have adverse reactions. Rehmannia glutinosa is a herb used in traditional Chinese medicine, which can promote bone-marrow proliferation and protect the ischemic myocardium. We investigated the effects of Rehmannia glutinosa extract (RGE) on EPCs in a rat model of MI. Methods A total of 120 male Wistar rats were randomized to 2 groups (n = 60 each) for treatment: high-dose RGE (1.5 g·kg−1·day−1 orally) for 8 weeks, then left anterior descending coronary artery ligation, mock surgery or no treatment, then RGE orally for 4 weeks; or normal saline (NS) as the above protocol. The infarct region of the left ventricle was assessed by serial sectioning and morphology. EPCs were evaluated by number and function. Protein and mRNA levels of CD133, vascular endothelial growth factor receptor 2 (VEGFR2), chemokine C-X-C motif receptor 4 (CXCR4), stromal cell–derived factor-1α (SDF-1α) were measured by immunohistochemistry, Western blot and quantitative PCR analysis. Results RGE significantly improved left ventricular function, decreased the ischemic area and the apoptotic index in the infarct myocardium, also decreased the concentration of serum cardiac troponin T and brain natriuretic peptide at the chronic stage after MI (from week 2 to week 4). RGE increased EPC number, proliferation, migration and tube-formation capacity. It was able to up-regulate the expression of angiogenesis-associated ligand/receptor, including CD133, VEGFR2 and SDF-1α/CXCR4. In vitro, the effect of RGE on SDF-1α/CXCR4 cascade was reversed by the CXCR4 specific antagonist AMD3100. Conclusion RGE may enhance the mobilization, migration and therapeutic angiogenesis of EPCs after MI by activating the SDF-1α/CXCR4 cascade. PMID:23349848

  7. Remembering Words in Context as Predicted by an Associative Read-Out Model

    PubMed Central

    Hofmann, Markus J.; Kuchinke, Lars; Biemann, Chris; Tamm, Sascha; Jacobs, Arthur M.

    2011-01-01

    Interactive activation models (IAMs) simulate orthographic and phonological processes in implicit memory tasks, but they neither account for associative relations between words nor explicit memory performance. To overcome both limitations, we introduce the associative read-out model (AROM), an IAM extended by an associative layer implementing long-term associations between words. According to Hebbian learning, two words were defined as “associated” if they co-occurred significantly often in the sentences of a large corpus. In a study-test task, a greater amount of associated items in the stimulus set increased the “yes” response rates of non-learned and learned words. To model test-phase performance, the associative layer is initialized with greater activation for learned than for non-learned items. Because IAMs scale inhibitory activation changes by the initial activation, learned items gain a greater signal variability than non-learned items, irrespective of the choice of the free parameters. This explains why the slope of the z-transformed receiver-operating characteristics (z-ROCs) is lower one during recognition memory. When fitting the model to the empirical z-ROCs, it likewise predicted which word is recognized with which probability at the item-level. Since many of the strongest associates reflect semantic relations to the presented word (e.g., synonymy), the AROM merges form-based aspects of meaning representation with meaning relations between words. PMID:22007183

  8. An Explanation of Reading Comprehension across Development Using Models from Cattell-Horn-Carroll Theory: Support for Integrative Models of Reading

    ERIC Educational Resources Information Center

    Floyd, Randy; Meisinger, Elizabeth; Gregg, Noel; Keith, Timothy

    2012-01-01

    The purpose of this research was to investigate the cognitive abilities that explain reading comprehension across childhood and early adulthood. Drawing from the standardization sample of the Woodcock-Johnson III, analyses were conducted with large samples at age levels spanning early childhood to early adulthood: 5 to 6 (n = 639), 7 to 8 (n =…

  9. The Relationship of Print Reading in Tier I Instruction and Reading Achievement for Kindergarten Students at Risk of Reading Difficulties

    ERIC Educational Resources Information Center

    Wanzek, Jeanne; Roberts, Greg; Al Otaiba, Stephanie; Kent, Shawn C.

    2014-01-01

    For many students at risk of reading difficulties, effective, early reading instruction can improve reading outcomes and set them on a positive reading trajectory. Thus, response-to-intervention models include a focus on a student's Tier I reading instruction as one element for preventing reading difficulties and identifying students with a…

  10. Reading Faster

    ERIC Educational Resources Information Center

    Nation, Paul

    2009-01-01

    This article describes the visual nature of the reading process as it relates to reading speed. It points out that there is a physical limit on normal reading speed and beyond this limit the reading process will be different from normal reading where almost every word is attended to. The article describes a range of activities for developing…

  11. Cascading failure and robustness in metabolic networks.

    PubMed

    Smart, Ashley G; Amaral, Luis A N; Ottino, Julio M

    2008-09-09

    We investigate the relationship between structure and robustness in the metabolic networks of Escherichia coli, Methanosarcina barkeri, Staphylococcus aureus, and Saccharomyces cerevisiae, using a cascading failure model based on a topological flux balance criterion. We find that, compared to appropriate null models, the metabolic networks are exceptionally robust. Furthermore, by decomposing each network into rigid clusters and branched metabolites, we demonstrate that the enhanced robustness is related to the organization of branched metabolites, as rigid cluster formations in the metabolic networks appear to be consistent with null model behavior. Finally, we show that cascading in the metabolic networks can be described as a percolation process.

  12. Cascades Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Driedger, Carolyn; Pallister, John

    2008-01-01

    Washington's Mount St. Helens volcano reawakens explosively on October 1, 2004, after 18 years of quiescence. Scientists at the U.S. Geological Survey's Cascades Volcano Observatory (CVO) study and observe Mount St. Helens and other volcanoes of the Cascade Range in Washington, Oregon, and northern California that hold potential for future eruptions. CVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Mount St. Helens and CVO at http://vulcan.wr.usgs.gov/.

  13. Triangular rogue wave cascades.

    PubMed

    Kedziora, David J; Ankiewicz, Adrian; Akhmediev, Nail

    2012-11-01

    By numerically applying the recursive Darboux transformation technique, we study high-order rational solutions of the nonlinear Schrödinger equation that appear spatiotemporally as triangular arrays of Peregrine solitons. These can be considered as rogue wave cascades and complement previously discovered circular cluster forms. In this analysis, we reveal a general parametric restriction for their existence and investigate the interplay between cascade and cluster forms. As a result, we demonstrate how to generate many more hybrid rogue wave solutions, including semicircular clusters that resemble claws.

  14. The Geant4 Bertini Cascade

    SciTech Connect

    Wright, D. H.; Kelsey, M. H.

    2015-12-01

    One of the medium energy hadron–nucleus interaction models in the Geant4 simulation toolkit is based partly on the Bertini intranuclear cascade model. Since its initial appearance in the toolkit, this model has been largely re-written in order to extend its physics capabilities and to reduce its memory footprint. Physics improvements include extensions in applicable energy range and incident particle types, and improved hadron–nucleon cross-sections and angular distributions. Interfaces have also been developed which allow the model to be coupled with other Geant4 models at lower and higher energies. The inevitable speed reductions due to enhanced physics have been mitigated by memory and CPU efficiency improvements. Details of these improvements, along with selected comparisons of the model to data, are discussed.

  15. Interband Cascade Photovoltaic Cells

    SciTech Connect

    Yang, Rui Q.; Santos, Michael B.; Johnson, Matthew B.

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  16. Classifying Chinese children with dyslexia by dual-route and triangle models of Chinese reading.

    PubMed

    Wang, Li-Chih; Yang, Hsien-Ming

    2014-11-01

    This present study focuses on classifying developmental dyslexia by combining two famous models, the dual-route model and the triangle model of Chinese reading, re-examining validity of the subtypes, and observing the error types of word recognition for each subtype. Sixty-sixth graders with dyslexia in Chinese and 45 sixth graders who were matched by age and IQ with the dyslexic group were involved in the present study. Twelve (20%) sixth graders from the dyslexic group were classified as having phonological dyslexia, 11 (18.3%) were classified as surface dyslexia, 12 (20%) were classified as deep dyslexia, and five (8.3%) of them were classified as displaying more than one kind of deficit. Besides, still more than half (31; 51.7%) of the dyslexic group did not belong to any subtypes here. These subtypes had a good validity based on comparison of their phonological awareness, orthography, and semantics. Finally, for their error types of word recognition, both children with multiple-deficit dyslexia and children with non-subtype dyslexia showed a proportional pattern of six kinds of errors. Children with phonological dyslexia showed more phonetic errors and analogy errors, children with surface dyslexia showed more visual errors and analogy errors, and children with deep dyslexia showed more semantic errors and selective errors.

  17. Numerical characterization of non-Abelian Moore-Read state in the microscopic lattice boson model

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gong, Shoushu; Haldane, F. D. M.; Sheng, D. N.

    2015-03-01

    Identifying the interacting systems that host the non-Abelian (NA) topological phases have attracted intense attention in physics. Theoretically, it is possible to realize the NA Moore-Read (MR) state in bosonic system or double-layer system by coupling two Abelian fractional quantum Hall (FQH) states together. Here, based on the density matrix renormalization group and exact diagonalization calculations, we study two such examples in the microscopic lattice models and investigate their NA nature. In the first example, we provide a thorough characterization of the universal properties of MR state on Haldane honeycomb lattice model, including both the edge spectrum and the bulk anyonic quasiparticle statistics. By inspecting the entanglement spectral response to the U (1) flux, it is found that two of Abelian ground states can be adiabatically connected through a charge unit quasiparticle pumping from one edge to the other. In the second example, we study a double-layer bosonic FQH system built from the π-flux lattice model. Some evidences of NA nature has been identified, including the groundstate degeneracy and finite drag Hall conductance. The numerical methods we developed here provides a useful and practical way for detecting the full information of NA topological order. This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02-06ER46305.

  18. The Liège Intranuclear Cascade model - Towards a unified description of nuclear reactions induced by nucleons and light ions from a few MeV to a few GeV

    NASA Astrophysics Data System (ADS)

    Cugnon, Joseph; Boudard, Alain; David, Jean-Christophe; Leray, Sylvie; Mancusi, Davide

    2014-03-01

    The predictive power of the last version INCL4.6 of the Liège Intranuclear Cascade model for spallation is reviewed. The good results obtained both at low and high energy extend the domain of validity of the model and allow the description of spallation reactions, except the coherent processes, by a unique model from a few MeV to a few GeV incident energy.

  19. "Read Naturally": A Strategy To Increase Oral Reading Fluency.

    ERIC Educational Resources Information Center

    Hasbrouck, Jan E.; Ihnot, Candyce; Rogers, Ginger H.

    1999-01-01

    Describes the Read Naturally (RN) strategy to improve reading fluency that combines reading from a model, repeated readings, and progress-monitoring. Suggests positive results found in data collected from classroom implementations with K-3 remedial and special education students and 6th-grade special education students. (NH)

  20. A Test of a Linear Programming Model as an Optimal Solution to the Problem of Combining Methods of Reading Instruction

    ERIC Educational Resources Information Center

    Mills, James W.; And Others

    1973-01-01

    The Study reported here tested an application of the Linear Programming Model at the Reading Clinic of Drew University. Results, while not conclusive, indicate that this approach yields greater gains in speed scores than a traditional approach for this population. (Author)

  1. Representational Demands in Mothers' Talk to Preschool Children in Two Contexts: Picture Book Reading and a Modelling Task.

    ERIC Educational Resources Information Center

    Sorsby, Angela J.; Martlew, Margaret

    1991-01-01

    Examines mothers' discourse in joint picture book reading in terms of the level of abstract thought it requires the child to make and compares this with language used in an interactive, product-oriented task, modelling a clown using play-doh. (39 references) (GLR)

  2. The Effects of Modeling and Prompting Feedback Strategies on Sight Word Reading of Students Labeled Learning Disabled.

    ERIC Educational Resources Information Center

    Espin, Christine A.; Deno, Stanley L.

    1989-01-01

    The study with eight learning-disabled elementary grade students found modeling a more effective feedback strategy than prompting on subjects' sight word reading performance. Differences were generally maintained at one-month and three-month follow-up. (Author/DB)

  3. Efficient Word Reading: Automaticity of Print-Related Skills Indexed by Rapid Automatized Naming through Cusp-Catastrophe Modeling

    ERIC Educational Resources Information Center

    Sideridis, Georgios D.; Simos, Panagiotis; Mouzaki, Angeliki; Stamovlasis, Dimitrios

    2016-01-01

    The study explored the moderating role of rapid automatized naming (RAN) in reading achievement through a cusp-catastrophe model grounded on nonlinear dynamic systems theory. Data were obtained from a community sample of 496 second through fourth graders who were followed longitudinally over 2 years and split into 2 random subsamples (validation…

  4. Portuguese School Libraries Evaluation Model: An Analysis of Primary Schools' Results for the "Reading and Literacy" Domain

    ERIC Educational Resources Information Center

    Martins, Jorge Tiago; Martins, Rosa Maria

    2012-01-01

    This paper reports the implementation results of the Portuguese School Libraries Evaluation Model, more specifically the results of primary schools self-evaluation of their libraries' reading promotion and information literacy development activities. School libraries that rated their performance as either "Excellent" or "Poor"…

  5. Unraveling low-resolution structural data of large biomolecules by constructing atomic models with experiment-targeted parallel cascade selection simulations

    NASA Astrophysics Data System (ADS)

    Peng, Junhui; Zhang, Zhiyong

    2016-07-01

    Various low-resolution experimental techniques have gained more and more popularity in obtaining structural information of large biomolecules. In order to interpret the low-resolution structural data properly, one may need to construct an atomic model of the biomolecule by fitting the data using computer simulations. Here we develop, to our knowledge, a new computational tool for such integrative modeling by taking the advantage of an efficient sampling technique called parallel cascade selection (PaCS) simulation. For given low-resolution structural data, this PaCS-Fit method converts it into a scoring function. After an initial simulation starting from a known structure of the biomolecule, the scoring function is used to pick conformations for next cycle of multiple independent simulations. By this iterative screening-after-sampling strategy, the biomolecule may be driven towards a conformation that fits well with the low-resolution data. Our method has been validated using three proteins with small-angle X-ray scattering data and two proteins with electron microscopy data. In all benchmark tests, high-quality atomic models, with generally 1-3 Å from the target structures, are obtained. Since our tool does not need to add any biasing potential in the simulations to deform the structure, any type of low-resolution data can be implemented conveniently.

  6. Cascade photo production at CLAS

    SciTech Connect

    Goetz, John; Hicks, Kenneth H.

    2014-09-01

    The famous discovery of the Omega in 1964 put the quark model on firm ground and since then a lot of effort has been spent on mapping out the baryonic and mesonic states. Over the following decades, many excited baryons with light quarks (up, down and strange) have been measured, but by most predictions, only a small percentage of those expected have been found. In this talk, I will discuss a newly developing technique using an (unflavored) photon beam to excite protons to doubly-strange "Cascade" (Xi) states. Advantages of such an experiment and associated difficulties will be presented, along with recent results from the CLAS detector at Jefferson Lab in Virginia.

  7. Observed and modelled effects of auroral precipitation on the thermal ionospheric plasma: comparing the MICA and Cascades2 sounding rocket events

    NASA Astrophysics Data System (ADS)

    Lynch, K. A.; Gayetsky, L.; Fernandes, P. A.; Zettergren, M. D.; Lessard, M.; Cohen, I. J.; Hampton, D. L.; Ahrns, J.; Hysell, D. L.; Powell, S.; Miceli, R. J.; Moen, J. I.; Bekkeng, T.

    2012-12-01

    Auroral precipitation can modify the ionospheric thermal plasma through a variety of processes. We examine and compare the events seen by two recent auroral sounding rockets carrying in situ thermal plasma instrumentation. The Cascades2 sounding rocket (March 2009, Poker Flat Research Range) traversed a pre-midnight poleward boundary intensification (PBI) event distinguished by a stationary Alfvenic curtain of field-aligned precipitation. The MICA sounding rocket (February 2012, Poker Flat Research Range) traveled through irregular precipitation following the passage of a strong westward-travelling surge. Previous modelling of the ionospheric effects of auroral precipitation used a one-dimensional model, TRANSCAR, which had a simplified treatment of electric fields and did not have the benefit of in situ thermal plasma data. This new study uses a new two-dimensional model which self-consistently calculates electric fields to explore both spatial and temporal effects, and compares to thermal plasma observations. A rigorous understanding of the ambient thermal plasma parameters and their effects on the local spacecraft sheath and charging, is required for quantitative interpretation of in situ thermal plasma observations. To complement this TRANSCAR analysis we therefore require a reliable means of interpreting in situ thermal plasma observation. This interpretation depends upon a rigorous plasma sheath model since the ambient ion energy is on the order of the spacecraft's sheath energy. A self-consistent PIC model is used to model the spacecraft sheath, and a test-particle approach then predicts the detector response for a given plasma environment. The model parameters are then modified until agreement is found with the in situ data. We find that for some situations, the thermal plasma parameters are strongly driven by the precipitation at the observation time. For other situations, the previous history of the precipitation at that position can have a stronger

  8. Evaluation of Two Soil Water Redistribution Models (Finite Difference and Hourly Cascade Approach) Through The Comparison of Continuous field Sensor-Based Measurements

    NASA Astrophysics Data System (ADS)

    Ferreyra, R.; Stockle, C. O.; Huggins, D. R.

    2014-12-01

    Soil water storage and dynamics are of critical importance for a variety of processes in terrestrial ecosystems, including agriculture. Many of those systems are under significant pressure in terms of water availability and use. Therefore, assessing alternative scenarios through hydrological models is an increasingly valuable exercise. Soil water holding capacity is defined by the concepts of soil field capacity and plant available water, which are directly related to soil physical properties. Both concepts define the energy status of water in the root system and closely interact with plant physiological processes. Furthermore, these concepts play a key role in the environmental transport of nutrients and pollutants. Soil physical parameters (e.g. saturated hydraulic conductivity, total porosity and water release curve) are required as input for field-scale soil water redistribution models. These parameters are normally not easy to measure or monitor, and estimation through pedotransfer functions is often inadequate. Our objectives are to improve field-scale hydrological modeling by: (1) assessing new undisturbed methodologies for determining important soil physical parameters necessary for model inputs; and (2) evaluating model outputs, making a detailed specification of soil parameters and the particular boundary condition that are driving water movement under two contrasting environments. Soil physical properties (saturated hydraulic conductivity and determination of water release curves) were quantified using undisturbed laboratory methodologies for two different soil textural classes (silt loam and sandy loam) and used to evaluate two soil water redistribution models (finite difference solution and hourly cascade approach). We will report on model corroboration results performed using in situ, continuous, field measurements with soil water content capacitance probes and digital tensiometers. Here, natural drainage and water redistribution were monitored

  9. A Model for K-12 Reading Achievement through University/School District Collaboration.

    ERIC Educational Resources Information Center

    Turner, Trevor A.; Williams, Claudette H.

    Ongoing professional development is at the core of Project Reading Excellence at "Boggsville" Elementary School (a pseudonym) and is intricately woven throughout all related activities. This professional development program is built on the pillars of sound scientific-based reading research, best teaching practices, and appropriate…

  10. Building, Implementing, & Sustaining a Beginning Reading Model: School by School and Lessons Learned.

    ERIC Educational Resources Information Center

    Simmons, Deborah C.; Kame'enui, Edward J.; Good, Roland H., III; Harn, Beth A.; Cole, Carl; Braun, Drew

    2000-01-01

    Syntheses of reading research conducted by the National Research Council (1998) and more recently by the Congressionally-Commissioned National Reading Panel (2000) provide ample evidence of the skills, experience, and knowledge children need to become successful readers in an alphabetic writing system. This research makes clear that children must…

  11. PS 115 Alpha One Reading Program, New York, New York. Compensatory Education, Model Programs.

    ERIC Educational Resources Information Center

    American Institutes for Research in the Behavioral Sciences, Palo Alto, CA.

    During Public School (PS) 115's 1969-70 academic year, a first-grade class of 27 disadvantaged, inner city youngsters received a special language arts program entitled Alpha One. Alpha One is a commercial initial reading program designed to teach first grade children to read and write sentences containing words of one, two and three syllables, and…

  12. Modeling Child-Based Theoretical Reading Constructs with Struggling Adult Readers

    ERIC Educational Resources Information Center

    Nanda, Alice O.; Greenberg, Daphne; Morris, Robin

    2010-01-01

    This study examined whether measurement constructs behind reading-related tests for struggling adult readers are similar to what is known about measurement constructs for children. The sample included 371 adults reading between the third-and fifth-grade levels, including 127 men and 153 English speakers of other languages. Using measures of skills…

  13. A Model of Phonological Processing, Language, and Reading for Students with Mild Intellectual Disability

    ERIC Educational Resources Information Center

    Barker, R. Michael; Sevcik, Rose A.; Morris, Robin D.; Romski, MaryAnn

    2013-01-01

    Little is known about the relationships between phonological processing, language, and reading in children with intellectual disability (ID). We examined the structure of phonological processing in 294 school-age children with mild ID and the relationships between its components and expressive and receptive language and reading skills using…

  14. A Decision-Making Model of Reading Recovery Teaching: Figuring Out What To Do When.

    ERIC Educational Resources Information Center

    Jones, Noel K.

    2000-01-01

    Decision-making in Reading Recovery requires skills of observation and reflective analysis that many teachers have not had to learn in order to be good classroom teachers. This is because Reading Recovery sets the teacher a very complex task which involves the construction of a curriculum for each individual child--a curriculum that is…

  15. Cascaded thermoacoustic devices

    DOEpatents

    Swift, Gregory W.; Backhaus, Scott N.; Gardner, David L.

    2003-12-09

    A thermoacoustic device is formed with a resonator system defining at least one region of high specific acoustic impedance in an acoustic wave within the resonator system. A plurality of thermoacoustic units are cascaded together within the region of high specific acoustic impedance, where at least one of the thermoacoustic units is a regenerator unit.

  16. 'Cascade Gold' raspberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cascade Gold’ is a new gold fruited, floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). It has been evaluated at Puyallup, Wash. in plantings from 1988 to 2008. ...

  17. Quantum Cascade Lasers

    DTIC Science & Technology

    2007-11-02

    predicted small linewidth enhancement factor of QC lasers was measured in outside collaboration ( Prof . Shun-Lien Chuang at UIUC) and confirmed to be...Gmachl, Michael C. Wanke, Federico Capasso, Albert L. Hutchinson, Deborah L. Sivco, Sung- Nee G. Chu, and Alfred Y. Cho “Surface plasmon quantum cascade

  18. The Simple View of Reading as a Framework for National Literacy Initiatives: A Hierarchical Model of Pupil-Level and Classroom-Level Factors

    ERIC Educational Resources Information Center

    Savage, Robert; Burgos, Giovani; Wood, Eileen; Piquette, Noella

    2015-01-01

    The Simple View of Reading (SVR) describes Reading Comprehension as the product of distinct child-level variance in decoding (D) and linguistic comprehension (LC) component abilities. When used as a model for educational policy, distinct classroom-level influences of each of the components of the SVR model have been assumed, but have not yet been…

  19. Integrated Broadband Quantum Cascade Laser

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  20. Interpreting a CMS excess in l l j j +missing -transverse-momentum with the golden cascade of the minimal supersymmetric standard model

    NASA Astrophysics Data System (ADS)

    Allanach, Ben; Kvellestad, Anders; Raklev, Are

    2015-06-01

    The CMS experiment recently reported an excess consistent with an invariant mass edge in opposite-sign same flavor leptons, when produced in conjunction with at least two jets and missing transverse momentum. We provide an interpretation of the edge in terms of (anti)squark pair production followed by the "golden cascade" decay for one of the squarks: q ˜ →χ˜2 0q →l ˜ l q →χ˜1 0q l l in the minimal supersymmetric standard model. A simplified model involving binos, winos, an on-shell slepton, and the first two generations of squarks fits the event rate and the invariant mass edge. We check consistency with a recent ATLAS search in a similar region, finding that much of the good-fit parameter space is still allowed at the 95% confidence level (C.L.). However, a combination of other LHC searches, notably two-lepton stop pair searches and jets plus p T, rule out all of the remaining parameter space at the 95% C.L.