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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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  2. 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. PMID:22309087

  3. 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…

  4. 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…

  5. Developmental Dyslexia and the Dual Route Model of Reading: Simulating Individual Differences and Subtypes

    ERIC Educational Resources Information Center

    Ziegler, Johannes C.; Castel, Caroline; Pech-Georgel, Catherine; George, Florence; Alario, F-Xavier; Perry, Conrad

    2008-01-01

    Developmental dyslexia was investigated within a well-understood and fully specified computational model of reading aloud: the dual route cascaded model (DRC [Coltheart, M., Rastle, K., Perry, C., Langdon, R., & Ziegler, J.C. (2001). DRC: A dual route cascaded model of visual word recognition and reading aloud. Psychological Review, 108,…

  6. 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.

  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. 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.

  10. Modeling techniques for quantum cascade lasers

    SciTech Connect

    Jirauschek, Christian; Kubis, Tillmann

    2014-03-15

    Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.

  11. Degravitation features in the cascading gravity model

    NASA Astrophysics Data System (ADS)

    Moyassari, Parvin; Minamitsuji, Masato

    2013-07-01

    We obtain the effective gravitational equations on the codimension-2 and codimension-1 branes in the cascading gravity model. We then apply our formulation to the cosmological case and obtain the effective Friedmann equations on the codimension-2 brane, which are generically given in terms of integro-differential equations. Adopting an approximation for which the thickness of the codimension-2 brane is much smaller than the Hubble horizon, we study the Minkowski and de Sitter codimension-2 brane solutions. Studying the cosmological solutions shows that the cascading model exhibits the features necessary for degravitation of the cosmological constant. We also show that only the branch which does not have the smooth limit to the self-accelerating branch in the five-dimensional model in the absence of the bulk gravity can satisfy the null energy condition as the criterion of the stability. Note that our solutions are obtained in a different setup from that of the original cascading gravity model in the sense that the codimension-1 brane contains matter fields other than the pure tension.

  12. Computational Modeling of Reading in Semantic Dementia: Comment on Woollams, Lambon Ralph, Plaut, and Patterson (2007)

    ERIC Educational Resources Information Center

    Coltheart, Max; Tree, Jeremy J.; Saunders, Steven J.

    2010-01-01

    Woollams, Lambon Ralph, Plaut, and Patterson (see record 2007-05396-004) reported detailed data on reading in 51 cases of semantic dementia. They simulated some aspects of these data using a connectionist parallel distributed processing (PDP) triangle model of reading. We argue here that a different model of reading, the dual route cascaded (DRC)…

  13. 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.

  14. Heavy quarkonium cascades in the glueball model

    SciTech Connect

    Zuk, J.; Joshi, G.C.

    1984-05-01

    The OZI ciolating two pion cascades between /sup 3/Si states of heavy quarkonium (V' ..-->.. V/sup pipi/) are studied in the Freund--Nambu model. When interpreted in the context of QCD, this model implies that OZI violation results from mixing with an intermediate glueball state. It is found that for an appropriate flavour--symmetry--breaking scheme, cascades between the same quantum numbers are satisfactorily described by varying only the quarkonium masses. Some predictions are made. But, the observed suppression of GAMMA(..gamma..'' ..-->.. ..gamma pi pi..)/GAMMA(..gamma..' ..-->.. ..gamma pi pi..)= indicates that the QQ bound state nature of heavy quarkonia is an important consideration in these decays. We show that the quarkonium couplings depend on overlap integrals between the wavefunctions of the mesons present at the decay vertex. We discuss various models that exploit the non-relativistic nature of heavy quarkonia, and from which such overlap integrals are derived in terms of ''charmonium--model'' radial wavefunctions.

  15. 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…

  16. 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

  17. Nested Incremental Modeling in the Development of Computational Theories: The CDP+ Model of Reading Aloud

    ERIC Educational Resources Information Center

    Perry, Conrad; Ziegler, Johannes C.; Zorzi, Marco

    2007-01-01

    At least 3 different types of computational model have been shown to account for various facets of both normal and impaired single word reading: (a) the connectionist triangle model, (b) the dual-route cascaded model, and (c) the connectionist dual process model. Major strengths and weaknesses of these models are identified. In the spirit of…

  18. Models of the Reading Process

    PubMed Central

    Rayner, Keith; Reichle, Erik D.

    2010-01-01

    Reading is a complex skill involving the orchestration of a number of components. Researchers often talk about a “model of reading” when talking about only one aspect of the reading process (for example, models of word identification are often referred to as “models of reading”). Here, we review prominent models that are designed to account for (1) word identification, (2) syntactic parsing, (3) discourse representations, and (4) how certain aspects of language processing (e.g., word identification), in conjunction with other constraints (e g., limited visual acuity, saccadic error, etc.), guide readers’ eyes. Unfortunately, it is the case that these various models addressing specific aspects of the reading process seldom make contact with models dealing with other aspects of reading. Thus, for example, the models of word identification seldom make contact with models of eye movement control, and vice versa. While this may be unfortunate in some ways, it is quite understandable in other ways because reading itself is a very complex process. We discuss prototypical models of aspects of the reading process in the order mentioned above. We do not review all possible models, but rather focus on those we view as being representative and most highly recognized. PMID:21170142

  19. Cascade Models of Turbulence and Mixing

    NASA Astrophysics Data System (ADS)

    Kadanoff, Leo P.

    1997-01-01

    This note describes two kinds of work on turbulence. First it describes a simplified model of turbulent energy-cascades called the GOY model. Second it mentions work on a model of mixing in fluids. In addition to a brief historical discussion, I include some mention of our own work carried on at the University of Chicago by Jane Wang, Detlef Lohse, Roberto Benzi, Norbert Schörghofer, Scott Wunsch, Tong Zhou and myself. Our own studies are in large measure the outgrowth of a paper by M. H. Jensen, G. Paladin, and A. Vulpiani [1]. I mention this connection with some sadness because I recall Paladin's recent death in a mountain accident.

  20. Modeling a mountain basin sediment cascade

    NASA Astrophysics Data System (ADS)

    Bennett, Georgie; Molnar, Peter; McArdell, Brian; Burlando, Paolo

    2013-04-01

    Mountain basins are most sensitive to climate change because of the dependence of snow and ice melt processes, surface weathering and erosion on air temperature, combined with their rapid rainfall-runoff response. Consequently, sediment yield from mountain basins will also likely be related to climate variability. Constructing sediment budgets is the first step towards understanding the interaction of climate and earth-surface processes. Recently, mountain basin sediment transfer has been conceptualized as a sediment cascade in which, following erosion, sediment travels through multiple cycles of storage and remobilization before exiting the basin. However, few studies have extended this concept beyond the identification and quantification of individual processes and storage units. In this study we have developed a probabilistic sediment cascade model based on a sediment budget spanning more than 4 decades in the Illgraben, an active, debris-flow prone basin in the Swiss Alps. We use this model to investigate the role of thresholds and hydrological and sediment storage dynamics in the transformation of the observed probability distribution of slope failures into that of debris flows. The sediment cascade model consists of a hydrological and sediment module, both of which are based on a spatially lumped storage reservoir representation of the involved physical processes. Water and sediment are generated and routed according to conceptual rules and thresholds which we define and calibrate based on observations. We run simulations with stochastic sediment input drawn from the power-law distribution of slope failures and observed climatic variables (precipitation and air temperature) at the daily resolution for the period 2000-2009, and investigate the outputs of the model in terms of (1) the probability distribution and (2) the timing of sediment discharge events compared to observed debris flows. The triggering of debris flows in our model is conditioned by the

  1. Computer modeling results on all-Si cascade solar cells

    NASA Technical Reports Server (NTRS)

    Sparks, P. D.; Allen, F. G.; Daud, T.

    1984-01-01

    The properties of a cascade solar cell made entirely of silicon are investigated numerically with the goal of developing an optimal silicon solar cell grown by molecular-beam epitaxy. The cascade cell is modeled as two standard back-surface field cells with abrupt junctions connected by a tunnel junction. A cascade cell would have approximately twice the open-circuit voltage of a single cell. If the minority carriers generated in the front cell can be reflected before reaching the tunnel junction, then the cascade cell will show an increase in efficiency over a single cell by a percentage point.

  2. 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.

  3. Models for Shelf Reading

    ERIC Educational Resources Information Center

    Bookstein, Abraham

    1973-01-01

    Though unshelved books are a problem in every library, little systematic effort has been made to design an optimal solution. Presented here is a mathematical model that attempts to approach such a solution. (2 references) (Author/DH)

  4. CASCADER: An m-chain gas-phase radionuclide transport and fate model. [CASCADER Model

    SciTech Connect

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

    1992-06-01

    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 as they are advected and/or dispersed. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one space dimensional transport and fate model for an m-chain of radionuclides in very dry soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advocation velocity is derived from an embedded air-pumping submodel. The airpumping submodel is based on an assumption of isothermal conditions and is barometric pressure driven. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions is used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77.

  5. Experimental basis for the models of cascade propagation in atmosphere

    NASA Technical Reports Server (NTRS)

    Strugalski, Z.

    1985-01-01

    The picture of the hadron nucleus collision process is presented as it emerges on the basis of newly obtained experimental data. The picture is applicable to models of cascade propagation in Earth atmosphere.

  6. 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.

  7. 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…

  8. Uncertainty propagation in a cascade modelling approach to flood mapping

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rincón, J. P.; Pedrozo-Acuña, A.; Breña Naranjo, J. A.

    2014-07-01

    The purpose of this investigation is to study the propagation of meteorological uncertainty within a cascade modelling approach to flood mapping. The methodology is comprised of a Numerical Weather Prediction Model (NWP), a distributed rainfall-runoff model and a standard 2-D hydrodynamic model. The cascade of models is used to reproduce an extreme flood event that took place in the Southeast of Mexico, during November 2009. The event is selected as high quality field data (e.g. rain gauges; discharge) and satellite imagery are available. Uncertainty in the meteorological model (Weather Research and Forecasting model) is evaluated through the use of a multi-physics ensemble technique, which considers twelve parameterization schemes to determine a given precipitation. The resulting precipitation fields are used as input in a distributed hydrological model, enabling the determination of different hydrographs associated to this event. Lastly, by means of a standard 2-D hydrodynamic model, hydrographs are used as forcing conditions to study the propagation of the meteorological uncertainty to an estimated flooded area. Results show the utility of the selected modelling approach to investigate error propagation within a cascade of models. Moreover, the error associated to the determination of the runoff, is showed to be lower than that obtained in the precipitation estimation suggesting that uncertainty do not necessarily increase within a model cascade.

  9. 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

  10. 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.

  11. 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. (PsycINFO Database Record PMID:26641449

  12. INCAS: an analytical model to describe displacement cascades

    NASA Astrophysics Data System (ADS)

    Jumel, Stéphanie; Claude Van-Duysen, Jean

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  13. 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.

  14. 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

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

    DOE Data Explorer

    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

  16. Cascade modeling of single and two-phase turbulence

    NASA Astrophysics Data System (ADS)

    Bolotnov, Igor A.

    The analysis of turbulent two-phase flows requires closure models in order to perform reliable computational multiphase fluid dynamics (CFMD) analyses. A turbulence cascade model, which tracks the evolution of the turbulent kinetic energy between the various eddy sizes, has been developed for the analysis of the single and bubbly two-phase turbulence. Various flows are considered including the decay of isotropic grid-induced turbulence, uniform shear flow and turbulent channel flow. The model has been developed using a "building block" approach by moving from modeling of simpler turbulent flows (i.e., homogeneous, isotropic decay) to more involved turbulent flows (i.e., non-homogeneous channel flow). The spectral cascade-transport model's performance has been assessed against a number of experimental and direct numerical simulation (DNS) results.

  17. 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.

  18. 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.

  19. "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…

  20. Cascading rainfall uncertainties into 2D inundation impact models

    NASA Astrophysics Data System (ADS)

    Souvignet, Maxime; de Almeida, Gustavo; Champion, Adrian; Garcia Pintado, Javier; Neal, Jeff; Freer, Jim; Cloke, Hannah; Odoni, Nick; Coxon, Gemma; Bates, Paul; Mason, David

    2013-04-01

    Existing precipitation products show differences in their spatial and temporal distribution and several studies have presented how these differences influence the ability to predict hydrological responses. However, an atmospheric-hydrologic-hydraulic uncertainty cascade is seldom explored and how, importantly, input uncertainties propagate through this cascade is still poorly understood. Such a project requires a combination of modelling capabilities, runoff generation predictions based on those rainfall forecasts, and hydraulic flood wave propagation based on the runoff predictions. Accounting for uncertainty in each component is important in decision making for issuing flood warnings, monitoring or planning. We suggest a better understanding of uncertainties in inundation impact modelling must consider these differences in rainfall products. This will improve our understanding of the input uncertainties on our predictive capability. 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, i.e. testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products). Our method cascades rainfall uncertainties into a lumped hydrologic model (FUSE) within the GLUE uncertainty framework. The resultant prediction uncertainties in discharge provide uncertain boundary conditions, which are cascaded into a simplified shallow water 2D hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded data and numerical weather predictions (NWP) models are used to assess the combined input data and model parameter uncertainty. The study is performed in the Severn catchment over the period between June and July 2007, where a series of rainfall events causing record floods in the study area). Changes in flood area extent are compared and the uncertainty envelope is

  1. 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

  2. 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.

  3. Computational modeling of leukocyte adhesion cascade (LAC)

    NASA Astrophysics Data System (ADS)

    Sarkar, Kausik

    2005-11-01

    In response to an inflammation in the body, leukocytes (white blood cell) interact with the endothelium (interior wall of blood vessel) through a series of steps--capture, rolling, adhesion and transmigration--critical for proper functioning of the immune system. We are numerically simulating this process using a Front-tracking finite-difference method. The viscoelastcity of the cell membrane, cytoplasm and nucleus are incorporated and allowed to change with time in response to the cell surface molecular chemistry. The molecular level forces due to specific ligand-receptor interactions are accounted for by stochastic spring-peeling model. Even though leukocyte rolling has been investigated through various models, the transitioning through subsequent steps, specifically firm adhesion and transmigration through endothelial layer, has not been modeled. The change of viscoelastic properties due to the leukocyte activation is observed to play a critical role in mediating the transition from rolling to transmigration. We will provide details of our approach and discuss preliminary results.

  4. 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.

  5. The reading efficiency model: an extension of the componential model of reading.

    PubMed

    Høien-Tengesdal, Ingjerd; Høien, Torleiv

    2012-01-01

    The purpose of the present study was twofold: First, the authors investigated if an extended version of the component model of reading (CMR; Model 2), including decoding rate and oral vocabulary comprehension, accounted for more of the variance in reading comprehension than the commonly used measures of the cognitive factors in the CMR. Second, the authors investigated the fitness of a new model, titled the reading efficiency model (REM), which deviates from earlier models regarding how reading is defined. In the study, 780 Norwegian students from Grades 6 and 10 were recruited. Here, hierarchical regression analyses showed that the extended model did not account for more of the variance in reading comprehension than the traditional CMR model (Model 1). In the second part of the study the authors used structural equation modeling (SEM) to explore the REM. The results showed that the REM explained an overall larger amount of variance in reading ability, compared to Model 1 and Model 2. This result is probably the result of the new definition of reading applied in the REM. The authors believe their model will more fully reflects students' differentiated reading skills by including reading fluency in the definition of reading. PMID:22293685

  6. 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.

  7. Nested incremental modeling in the development of computational theories: the CDP+ model of reading aloud.

    PubMed

    Perry, Conrad; Ziegler, Johannes C; Zorzi, Marco

    2007-04-01

    At least 3 different types of computational model have been shown to account for various facets of both normal and impaired single word reading: (a) the connectionist triangle model, (b) the dual-route cascaded model, and (c) the connectionist dual process model. Major strengths and weaknesses of these models are identified. In the spirit of nested incremental modeling, a new connectionist dual process model (the CDP+ model) is presented. This model builds on the strengths of 2 of the previous models while eliminating their weaknesses. Contrary to the dual-route cascaded model, CDP+ is able to learn and produce graded consistency effects. Contrary to the triangle and the connectionist dual process models, CDP+ accounts for serial effects and has more accurate nonword reading performance. CDP+ also beats all previous models by an order of magnitude when predicting individual item-level variance on large databases. Thus, the authors show that building on existing theories by combining the best features of previous models--a nested modeling strategy that is commonly used in other areas of science but often neglected in psychology--results in better and more powerful computational models. PMID:17500628

  8. The Collisional Cascade Model For Saturn's Ring Spokes

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.; Jontof-Hutter, D.

    2014-12-01

    Dust particles are ubiquitous in the saturnian system, spewing forth from the geysers of Enceladus and lurking as mysterious wedge-shaped spokes in the planet's main rings. The smallest dust grains are strongly influenced by electromagnetic forces arising from the motions of charged dust particles relative to Saturn's rotating magnetic field while large dust grains follow Keplerian paths determined by the planet's gravity. The most interesting dynamics result when the two forces have similar strengths, typically for particles ~100 nanometer in size. Differences between the motions of dust grains and much larger ring particles provides a free energy source that powers spoke formation. Most observations of ongoing spoke formation can be understood in the context of a Collisional Cascade model in which a hail of rapidly-moving ~50nm dust grains rain down upon more massive ring particles. After leaving the ring plane en masse from the site of an initial disturbance, these mid-sized grains are accelerated by the magnetic field to high speeds relative to ring particles. When they return to the ring plane - nearly simultaneously over a large radial range - they strike dust-coated fluffy ring particles, freeing both visible 0.5 micron spoke particles and additional 50nm debris that goes on to continue the cascade. The Collisional Cascade model can account for the rapid onset of spokes, their hour-long active phases, and the propensity of spokes to prefer certain magnetic longitudes.

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

    PubMed

    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. 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

  11. 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.

  12. Modified gravity, the Cascading DGP model and its critical tension

    NASA Astrophysics Data System (ADS)

    Sbisà, Fulvio

    2014-12-01

    We investigate the presence of instabilities in the Cascading DGP model. We start by discussing the problem of the cosmological late time acceleration, and we introduce the modified gravity approach. We then focus on brane induced gravity models and in particular on the Cascading DGP model. We consider configurations of the latter model where the source term is given simply by vacuum energy (pure tension), and we study perturbations at first order around these configurations. We perform a four-dimensional scalar-vector-tensor decomposition of the perturbations, and show that, regarding the scalar sector, the dynamics in a suitable limit can be described by a master equation. This master equation contains an energy scale (critical tension) which is related in a lion-trivial way to the parameters of the model. We give a geometrical interpretation of why this scale emerges, and explain its relevance for the presence of ghost instabilities in the theory. We comment on the difference between our result, and the one present in the literature, and stress its importance regarding the phenomenological viability of the model. We finally provide a numerical check which confirms the validity of our analysis.

  13. Model for vacancy-loop nucleation in displacement cascades

    NASA Astrophysics Data System (ADS)

    Kapinos, V. G.; Bacon, D. J.

    1995-08-01

    A model is proposed for the nucleation of collapsed vacancy clusters in irradiated metals, based on the principle that a vacancy loop may be nucleated in a cascade which has melted and recrystallized. The equation of thermal conduction is solved using the discretization method and initial temperature and vacancy distributions given by the marlowe code. The model simulates the processes of heat propagation, local melting, absorption and release of latent heat, and the redistribution of the density within the melt. Under the influence of the temperature gradient, the concentration of vacancies in the depleted zone increases. Simulation of hundreds of cascades gives the distribution of zones as a function of vacancy concentration and number of vacancies in them, and it is assumed that critical values Ccr and Ncrv have to be achieved to produce a visible vacancy loop. However, if the concentration exceeds a value Camv under sufficiently fast cooling, for example under strong electron-phonon coupling (EPC), the melted zone cannot crystallize completely and solidifies instead to a semiamorphous core. This prevents collapse to a vacancy loop. The model has been used to calculate the yield and mean size of vacancy loops in ion-irradiated Cu, Ni, and Cu-Ge and Cu-Ni alloys. Physically reasonable values of Ccr, Ncr, and Camv have been obtained to give good agreement with experimental values of yield and size. Furthermore, the trends with alloy content can be explained, and it is found that EPC can have a strong influence on loop yield.

  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. PMID:20085406

  15. "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. PMID:22343366

  16. 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.

  17. Some Text-Level Considerations for a Model of Reading.

    ERIC Educational Resources Information Center

    Kane, Janet H.

    Models of reading have been proposed to guide researchers and educators in their theoretical research and instructional planning. The models specify important properties of the material to be read and processes the learner uses while reading. Two separate models of reading by K.S. Goodman and D. Rumelhart are similar in that they describe reading…

  18. The development of reading impairment: a cognitive neuroscience model.

    PubMed

    McCandliss, Bruce D; Noble, Kimberly G

    2003-01-01

    This review discusses recent cognitive neuroscience investigations into the biological bases of developmental dyslexia, a common disorder impacting approximately 5 to 17 percent of the population. Our aim is to summarize central findings from several lines of evidence that converge on pivotal aspects of the brain bases of developmental dyslexia. We highlight ways in which the approaches and methodologies of developmental cognitive neuroscience that are addressed in this special issue-including neuroimaging, human genetics, refinement of cognitive and biological phenotypes, neural plasticity and computational model-can be employed in uncovering the biological bases of this disorder. Taking a developmental perspective on the biological bases of dyslexia, we propose a simple cascading model for the developmental progression of this disorder, in which individual differences in brain areas associated with phonological processing might influence the specialization of visual areas involved in the rapid processing of written words. We also discuss recent efforts to understand the impact of successful reading interventions in terms of changes within cortical circuits associated with reading ability. PMID:12953299

  19. Teacher Modeling: Its Impact on an Extensive Reading Program

    ERIC Educational Resources Information Center

    Loh, Jason Kok Khiang

    2009-01-01

    This case study investigates whether teachers model reading in 1 Singapore primary school during an exercise called "uninterrupted sustained silent reading" (USSR) carried out in the classroom. Even though reading is an important determinant of a student's growth in language skills and ability, and modeling the act of reading is essential in…

  20. 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

  1. Spoke Formation in Saturn's Ring: The Collisional Cascade Model

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas P.

    2014-11-01

    The mysterious wedge-shaped spokes in Saturn's main rings have defied explanation ever since their discovery during the Voyager flybys of the early 1980s. No earlier model can explain the three disparate timescales over which spokes evolve: i) the 10-minute formation time for a new spoke, ii) the hour-long period over which a spoke's radial edge remains active, and iii) the day-long timescale over which the magnetic longitude of earlier spoke activity is preferentially repopulated with subsequent spokes. This and other observations of ongoing spoke formation can be understood in the context of a Collisional Cascade model in which a hail of rapidly-moving submicron dust grains rain down upon more massive ring particles. Tiny ~0.1 micron grains leave the ring plane en masse from the site of an initial disturbance (likely a meteoroid impact) and are accelerated by the magnetic field to high speeds relative to more massive ring particles. When the dust returns to the ring plane -nearly simultaneously over a large radial range - they strike fluffy dust-coated ring particles at km/s speeds, freeing both visible 0.5 micron spoke particles and additional submicron debris. Differences between the motions of the 0.1 micron dust grains and the much larger ring particles provides a potent free energy source that powers spoke formation. The onset of this hail of tiny energetic impactors can account for the observed rapid formation of spokes and, as the hail continues to fall, for the hour-long active periods over which some spoke edges remains nearly radial. The hour-long timescale is controlled by differences in initial launch velocities and different grain charge-to-mass ratios which strongly affect vertical motions. Additional tiny grains liberated in the first hailstorm go on to continue the cascade, returning to strike the same magnetic longitude in the ring hours to days later and stirring up more micron-sized spoke particles. This continuing cascade nicely accounts for

  2. 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.

  3. 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.

  4. 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

  5. A simple model of global cascades on random networks

    PubMed Central

    Watts, Duncan J.

    2002-01-01

    The origin of large but rare cascades that are triggered by small initial shocks is a phenomenon that manifests itself as diversely as cultural fads, collective action, the diffusion of norms and innovations, and cascading failures in infrastructure and organizational networks. This paper presents a possible explanation of this phenomenon in terms of a sparse, random network of interacting agents whose decisions are determined by the actions of their neighbors according to a simple threshold rule. Two regimes are identified in which the network is susceptible to very large cascades—herein called global cascades—that occur very rarely. When cascade propagation is limited by the connectivity of the network, a power law distribution of cascade sizes is observed, analogous to the cluster size distribution in standard percolation theory and avalanches in self-organized criticality. But when the network is highly connected, cascade propagation is limited instead by the local stability of the nodes themselves, and the size distribution of cascades is bimodal, implying a more extreme kind of instability that is correspondingly harder to anticipate. In the first regime, where the distribution of network neighbors is highly skewed, it is found that the most connected nodes are far more likely than average nodes to trigger cascades, but not in the second regime. Finally, it is shown that heterogeneity plays an ambiguous role in determining a system's stability: increasingly heterogeneous thresholds make the system more vulnerable to global cascades; but an increasingly heterogeneous degree distribution makes it less vulnerable. PMID:16578874

  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. PMID:27581482

  7. 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

  8. 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…

  9. 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.

  10. 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…

  11. 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…

  12. 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.

  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. 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.

  15. 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…

  16. 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

  17. Predicting reading success in a multilevel schoolwide reading model: a retrospective analysis.

    PubMed

    Chard, David J; Stoolmiller, Mike; Harn, Beth A; Wanzek, Jeanne; Vaughn, Sharon; Linan-Thompson, Sylvia; Kame'enui, Edward J

    2008-01-01

    Despite recent research findings that implicate a long list of student variables that predict reading success or failure, these predictor variables have not been considered in the context of contemporary models of multitiered schoolwide reading intervention. This longitudinal, retrospective study follows 668 kindergarten and first-grade students identified as at risk for later reading difficulties through third grade. Key predictor variables were examined to determine their validity for predicting initial status and growth on oral reading fluency, third-grade oral reading fluency, and third-grade performance on a standardized test of reading. Results are provided in light of the instructional model provided. Implications for instruction and assessment are discussed. PMID:18354936

  18. 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…

  19. Motivating Boys to Read: Inquiry, Modeling, and Choice Matter

    ERIC Educational Resources Information Center

    Fisher, Douglas; Frey, Nancy

    2012-01-01

    A great deal of attention is being paid to the lack of reading and academic success for adolescent males. In this article, we discuss three structures in a school where boys read (and perform) as well as girls. When instruction is guided by inquiry, when teachers model their thinking while reading, and when book choices are honored, all students…

  20. A Time for Heresy: A Molar Reading Model.

    ERIC Educational Resources Information Center

    Williamson, Leon E.

    A survey of the literature concerning the mental processes used in reading reveals a proliferation of molecular theories which explain only a small (and frequently neurological) component of the reading act. Enough information exists, however, to sketch an integrated, molar model of the reading process, which stresses the interrelationships…

  1. Incorporating RTI in a Hybrid Model of Reading Disability.

    PubMed

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

    2014-08-01

    The present study seeks to evaluate a hybrid model of identification that incorporates response-to-intervention (RTI) as a one of the key symptoms of reading disability. The one-year stability of alternative operational definitions of reading disability was examined in a large scale sample of students who were followed longitudinally from first to second grade. The results confirmed previous findings of limited stability for single-criterion based operational definitions of reading disability. However, substantially greater stability was obtained for a hybrid model of reading disability that incorporates RTI with other common symptoms of reading disability. PMID:25422531

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

    SciTech Connect

    Ala Qubbaj

    2004-04-01

    Based on the physical and computational models outlined in the previous technical progress reports, Natural gas jet diffusion flames in baseline, cascade, swirl, and swirlcascade burners were numerically modeled. The thermal, composition, and flow (velocity) fields were simulated. The temperature, CO{sub 2} and O{sub 2} concentrations, as well as the axial and radial velocity profiles were computed and analyzed. 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''.

  3. Model of mass transfer processes in the cascade of centrifugal extractors

    NASA Astrophysics Data System (ADS)

    Zelenetskaya, E. P.; Goryunov, A. G.; Daneikina, N. V.

    2016-06-01

    The paper describes a mathematical model of mass transfer processes in a cascade of reverse-flow centrifugal extractors. Model of operation of each extractor is given as tightly coupled system of mixing and separating chambers. All model units are represented by systems of differential equations. The article presents the results of testing of the developed model, which confirmed the validity of the assumptions made in the model. The authors assessed the impact of the overflow of dense phase level on the hydrostatic position of phase interface level in the extractor. The research showed that a change in the volume of dense and light phases occurs in each apparatus of a cascade even in the steady mode. Operation of the cascade consisting of 12 series-connected centrifugal extractors was simulated in order to verify the model. Computer simulation results confirm the adequacy of the developed model.

  4. 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.

  5. An exploration of the emotional cascade model in borderline personality disorder.

    PubMed

    Selby, Edward A; Anestis, Michael D; Bender, Theodore W; Joiner, Thomas E

    2009-05-01

    The emotional cascade model proposes that the emotional and behavioral dysregulation of individuals with borderline personality disorder (BPD) may be fundamentally linked through emotional cascades, vicious cycles of intense rumination and negative affect that may induce aversive emotional states. In order to reduce this aversive emotion, dysregulated behaviors such as non-suicidal self-injury may then be used as distractions from intense rumination. This study explored emotional cascades in a sample enriched with participants meeting diagnostic criteria for BPD. The first part of the study explored a structural equation model that examined the mediational effects of emotional cascades on the relationship between BPD symptoms and dysregulated behavior and found evidence for full mediation, even after controlling for symptoms of depression and other Cluster B disorders. The second part of the study examined the effects of a rumination induction conducted with the intention of eliciting emotional cascades in those diagnosed with BPD. The results demonstrated that individuals with BPD experienced greater reactivity and intensity of negative affect, but not of positive affect, following the procedure-even when controlling for current depressive symptoms. Future directions and clinical implications for the emotional cascade model are discussed. PMID:19413411

  6. Applicability of dual-route reading models to Spanish.

    PubMed

    Ardila, Alfredo; Cuetos, Fernando

    2016-02-01

    Two opposing points of view have been presented with regard to the applicability of the dual-route reading models  Spanish. Some authors maintain that, given the transparency of the reading system, non-lexical reading is the strategy followed predominantly by Spanish readers and for that reason these models are not appropriate to explain alexias (acquired dyslexias) in Spanish. Other authors, consider that since several cases of phonological, surface and deep alexia have been reported, dual-route reading models are applicable to Spanish in the same way that to the irregular writing systems. In order to contrast these two points of view, an analysis of the two main factors that influence the reading is made: characteristics of the Spanish orthography and characteristics of the Spanish readers. It is conclude that, (1) Due to its transparency, non-lexical reading represents –as in other transparent orthographies-- the initial reading strategy in Spanish; (2) the “reading threshold” (i.e., time required to become literate) is lower in Spanish because there are no irregular words to learn; (3) as reading experience increases, speed increases and lexical reading becomes used more; (4) Given the characteristics of the Spanish reading system, it is understandable that frequency of deep dyslexia is so low. PMID:26820427

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

    PubMed

    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)] takes the form of exp(-gk). 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. PMID:26274272

  8. Can cognitive models explain brain activation during word and pseudoword reading? A meta-analysis of 36 neuroimaging studies.

    PubMed

    Taylor, J S H; Rastle, Kathleen; Davis, Matthew H

    2013-07-01

    Reading in many alphabetic writing systems depends on both item-specific knowledge used to read irregular words (sew, yacht) and generative spelling-sound knowledge used to read pseudowords (tew, yash). Research into the neural basis of these abilities has been directed largely by cognitive accounts proposed by the dual-route cascaded and triangle models of reading. We develop a framework that enables predictions for neural activity to be derived from cognitive models of reading using 2 principles: (a) the extent to which a model component or brain region is engaged by a stimulus and (b) how much effort is exerted in processing that stimulus. To evaluate the derived predictions, we conducted a meta-analysis of 36 neuroimaging studies of reading using the quantitative activation likelihood estimation technique. Reliable clusters of activity are localized during word versus pseudoword and irregular versus regular word reading and demonstrate a great deal of convergence between the functional organization of the reading system put forward by cognitive models and the neural systems activated during reading tasks. Specifically, left-hemisphere activation clusters are revealed reflecting orthographic analysis (occipitotemporal cortex), lexical and/or semantic processing (anterior fusiform, middle temporal gyrus), spelling-sound conversion (inferior parietal cortex), and phonological output resolution (inferior frontal gyrus). Our framework and results establish that cognitive models of reading are relevant for interpreting neuroimaging studies and that neuroscientific studies can provide data relevant for advancing cognitive models. This article thus provides a firm empirical foundation from which to improve integration between cognitive and neural accounts of the reading process. PMID:23046391

  9. 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.

  10. Generalized vortex model for the inverse cascade of two-dimensional turbulence

    NASA Astrophysics Data System (ADS)

    Friedrich, J.; Friedrich, R.

    2013-11-01

    We generalize Kirchhoff's point vortex model of two-dimensional fluid motion to a rotor model which exhibits an inverse cascade by the formation of rotor clusters. A rotor is composed of two vortices with like-signed circulations glued together by an overdamped spring. The model is motivated by a treatment of the vorticity equation representing the vorticity field as a superposition of vortices with elliptic Gaussian shapes of variable widths, augmented by a suitable forcing mechanism. The rotor model opens up the way to discuss the energy transport in the inverse cascade on the basis of dynamical systems theory.

  11. Generalized vortex model for the inverse cascade of two-dimensional turbulence.

    PubMed

    Friedrich, J; Friedrich, R

    2013-11-01

    We generalize Kirchhoff's point vortex model of two-dimensional fluid motion to a rotor model which exhibits an inverse cascade by the formation of rotor clusters. A rotor is composed of two vortices with like-signed circulations glued together by an overdamped spring. The model is motivated by a treatment of the vorticity equation representing the vorticity field as a superposition of vortices with elliptic Gaussian shapes of variable widths, augmented by a suitable forcing mechanism. The rotor model opens up the way to discuss the energy transport in the inverse cascade on the basis of dynamical systems theory. PMID:24329361

  12. 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.…

  13. 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. PMID:23686229

  14. Evaluating Individualized Reading Programs: A Bayesian Model.

    ERIC Educational Resources Information Center

    Maxwell, Martha

    Simple Bayesian approaches can be applied to answer specific questions in evaluating an individualized reading program. A small reading and study skills program located in the counseling center of a major research university collected and compiled data on student characteristics such as class, number of sessions attended, grade point average, and…

  15. Event-specific multiplicative cascade models and an application to rainfall

    NASA Astrophysics Data System (ADS)

    CâRsteanu, Alin; Venugopal, V.; Foufoula-Georgiou, Efi

    1999-01-01

    Multiplicative cascades offer parsimonious models capable of capturing the scale-invariant (multifractal scaling) behavior of some geophysical phenomena, such as rainfall, over a large range of scales. While these models achieve a remarkable degree of universality, it is still unclear how to characterize individual events within this framework. The present work offers an event description based on a few most important (amplitude-wise) branchings of the event's multiplicative cascade generator. The proposed method is based on the modulus extrema of wavelet transforms and indexes the branches (or generator weights in the multiplicative cascade model) such that their number at each branching, magnitude, and the relative scales at which they occur can be extracted and memorized. In this way, a particular event can be characterized in a multiplicative cascade framework by only a few significant weights and their respective positioning within the cascade. The application of the present model to rainfall is supported by the evidence of branching of the wavelet modulus extrema as well as by the findings [Venugopal and Foufoula-Georgiou, 1996; Cârsteanu et al., 1997] that an important part of the signal energy of temporal rainfall events can be recovered from a few wavelet-packet components.

  16. 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…

  17. 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

  18. Performance of a model cascade thrust reverser for short-haul applications

    NASA Technical Reports Server (NTRS)

    Dietrich, D. A.; Gutierrez, O. A.

    1974-01-01

    Aerodynamic and acoustic characteristics are presented for a cowlmounted, model cascade thrust reverser suitable for short-haul aircraft. Thrust reverser efficiency and the influence on fan performance were determined from isolated fan-driven models under static and forward velocity conditions. Cascade reverser noise characteristics were determined statically in an isolated pipe-flow test, while aerodynamic installation effects were determined with a wind-tunnel, fan-powered airplane model. Application of test results to short-haul aircraft calculations demonstrated that such a cascade thrust reverser may be able to meet both the performance and noise requirements for short-haul aircraft operation. However, aircraft installation effects can be quite significant.

  19. Modeling of self-healing against cascading overload failures in complex networks

    NASA Astrophysics Data System (ADS)

    Liu, Chaoran; Li, Daqing; Fu, Bowen; Yang, Shunkun; Wang, Yunpeng; Lu, Guangquan

    2014-09-01

    The development of online prognostic and fast-recovery technology promotes the realization of self-healing techniques. Considering the cascading overload failures as one of the major failure modes in real networks, we introduce a model for self-healing against overload propagation in complex networks due to malicious attack. Especially, we study the role of basic quantities (restoration timing and resource) in general self-healing restoration against cascading overload failures in network models of homogeneous (Erdős-Rényi) and heterogeneous (scale-free) networks. We demonstrate how networks during cascading failures can be saved from the brink of collapse by proper combination of both restoration timing and resource. And we find that optimal restoration timing for the model and realistic networks exists at a given restoration resource in the self-healing process.

  20. Modelling of multijunction cascade photovoltaics for space applications

    SciTech Connect

    Educato, J.L.

    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.

  1. 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.

  2. Modeling of fissile material diversion in solvent extraction cascades

    SciTech Connect

    Schneider, A.; Carlson, R.W.

    1980-05-22

    Changes were calculated for measurable parameters of a solvent extraction section of a reprocessing plant resulting from postulated fissile material diversion actions. The computer program SEPHIS was modified to calculate the time-dependent concentrations of uranium and plutonium in each stage of a cascade. The calculation of the inventories of uranium and plutonium in each contactor was also included. The concentration and inventory histories were computed for a group of four sequential columns during start-up and for postulated diversion conditions within this group of columns. Monitoring of column exit streams or of integrated column inventories for fissile materials could provide qualitative indications of attempted diversions. However, the time delays and resulting changes are complex and do not correlate quantitatively with the magnitude of the initiating event.

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

    PubMed

    Schroer, Kes; Wood, Bernard

    2015-02-01

    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 M3 s 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

  4. General model of a cascade of reactions with time delays: Global stability analysis

    NASA Astrophysics Data System (ADS)

    Bodnar, Marek

    2015-07-01

    The problem considered in this paper consists of a cascade of reactions with discrete as well as distributed delays, which arose in the context of Hes1 gene expression. For the abstract general model sufficient conditions for global stability are presented. Then the abstract result is applied to the Hes1 model.

  5. Charm quark energy loss in infinite QCD matter using a parton cascade model

    NASA Astrophysics Data System (ADS)

    Younus, Mohammed; Coleman-Smith, Christopher E.; Bass, Steffen A.; Srivastava, Dinesh K.

    2015-02-01

    We utilize the parton cascade model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient q ̂ for charm quarks. The calculations are done at a constant temperature of 350 MeV and the results are compared to analytical calculations of heavy-quark energy loss in order to validate the applicability of using a parton cascade model for the study of heavy-quark dynamics in hot and dense QCD matter.

  6. 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

  7. 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

  8. Schools as host environments: toward a schoolwide reading improvement model.

    PubMed

    Kame'enui, E J; Simmons, D C; Coyne, M D

    2000-01-01

    Despite vast differences among school districts across the country, all students must learn how to read in a complex "host-environment" called a school. A challenge in beginning reading, therefore, is to transcend these differences and focus, instead, on the essential task of teaching reading in schools. Teaching reading involves attending to what we know about beginning reading and the alphabetic writing system, the difficulties of reading, and the challenges associated with dyslexia. Teaching reading in a school requires that interventions be tailored to the unique needs of an individual school and implemented and sustained at the school building level. In this article, we outline the Schoolwide Reading Improvement Model (SRIM). This model is characterized by the strategic integration of research-based practices in assessment, instructional design, and beginning reading instruction. Additionally, the SRIM acknowledges the specific needs of individual schools and is customized to provide the best fit with each unique "host-environment." First we provide a description of each major stage of the SRIM and then an example of its application in a school district in western Oregon. PMID:20563779

  9. 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…

  10. 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. PMID:23386974

  11. 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

  12. 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 evaluation were to…

  13. 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…

  14. A NEW MODEL FOR GAMMA-RAY CASCADES IN EXTRAGALACTIC MAGNETIC FIELDS

    SciTech Connect

    Huan, H.; Weisgarber, T.; Wakely, S. P.; Arlen, T.

    2011-07-10

    Very high energy (VHE, E {approx}> 100 GeV) gamma rays emitted by extragalactic sources, such as blazars, initiate electromagnetic cascades in the intergalactic medium. The cascade photons arrive at the Earth with angular and temporal distributions correlated with the extragalactic magnetic field (EGMF). We have developed a new semi-analytical model of the cascade properties which is more accurate than previous analytic approaches and faster than full Monte Carlo simulations. Within its range of applicability, our model can quickly generate cascade spectra for a variety of source emission models, EGMF strengths, and assumptions about the source livetime. In this Letter, we describe the properties of the model and demonstrate its utility by exploring the gamma-ray emission from the blazar RGB J0710+591. In particular, we predict, under various scenarios, the VHE and high-energy (100 MeV {approx}< E {approx}< 300 GeV) fluxes detectable with the VERITAS and Fermi Large Area Telescope observatories. We then develop a systematic framework for comparing the predictions to published results, obtaining constraints on the EGMF strength. At a confidence level of 95%, we find the lower limit on the EGMF strength to be {approx}2 x 10{sup -16} G if no limit is placed on the livetime of the source or {approx}3 x 10{sup -18} G if the source livetime is limited to the past {approx}3 years during which Fermi observations have taken place.

  15. 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...

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

    ERIC Educational Resources Information Center

    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 5-18). Self, parent, teacher, peer, observer, and administrative reports…

  17. Cascade stability of the debris catalog under a two-component flux model

    SciTech Connect

    Canavan, G.H.

    1997-01-01

    Stability is analyzed with a two component model. The critical densities derived are in agreement with other estimates in the appropriate limits. The current catalog is stable for nominal decay parameters, although further growth or cascade coefficients higher than nominal could be causes for concern. Sources reduce stability, which is more of a problem at high altitudes than low.

  18. 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…

  19. The Difference Model: A New Explanation for Some Reading Difficulties

    ERIC Educational Resources Information Center

    Cromer, Ward

    1970-01-01

    Four models for accounting for reading difficulties are described: defect, deficit, disruption, and difference. Poor readers fitting two of these (difference and deficit) are compared with each other and with good readers. (Author)

  20. 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.

  1. 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

  2. A cascade model connecting life stress to risk behavior among rural African American emerging adults.

    PubMed

    Brody, Gene H; Chen, Yi-Fu; Kogan, Steven M

    2010-08-01

    A three-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

  3. 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

  4. Reading Comprehension of Scientific Text: A Domain-Specific Test of the Direct and Inferential Mediation Model of Reading Comprehension

    ERIC Educational Resources Information Center

    Cromley, Jennifer G.; Snyder-Hogan, Lindsey E.; Luciw-Dubas, Ulana A.

    2010-01-01

    Reading comprehension is strongly associated with academic achievement, including science achievement. A better understanding of reading comprehension processes in science text might hold promise for improving science achievement in the long run. We tested the fit of the direct and inferential mediation (DIME) model of reading comprehension…

  5. Observed and NWP simulated rainfall uncertainty cascading into rainfall-runoff and flood inundation impact models

    NASA Astrophysics Data System (ADS)

    Souvignet, M.; Freer, J. E.; de Almeida, G. A.; Coxon, G.; Neal, J. C.; Champion, A.; Cloke, H. L.; Bates, P. D.

    2013-12-01

    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 is still poorly understood. Such a project requires a combination of modelling capabilities, the non-linear transformation of rainfall to river flow using rainfall-runoff models, and hydraulic flood wave propagation based on the runoff predictions. Accounting for uncertainty 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 as part of the Framework for Understanding Structural Errors (FUSE). The resultant prediction uncertainties in upstream discharge provide uncertain boundary conditions which 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. The study is performed in the Severn catchment over summer 2007, where a series of

  6. Nuclear Reactions X-Sections By Evaporation Model, Gamma-Cascades

    Energy Science and Technology Software Center (ESTSC)

    2000-06-27

    Calculation of energy-averaged cross sections for nuclear reactions with emission of particles and gamma rays and fission. The models employed are the evaporation model with inclusion of pre-equilibrium decay and gamma ray cascade model. Angular momentum and parity conservation are accounted for. Major improvement to the 1976 STAPRE program (NEA 0461) relates to level density approach, implemwnted in subroutine ZSTDE. Generalized superfluid model is incorporated, Boltzman-gas modelling of intrinsic state density and semi-empirical modelling ofmore » a few quasiparticle effects in total level density in equilibrium and saddle deformations of actinide nuclei.« less

  7. 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.

  8. 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.

  9. A Model of Reading Teaching for University EFL Students: Need Analysis and Model Design

    ERIC Educational Resources Information Center

    Hamra, Arifuddin; Syatriana, Eny

    2012-01-01

    This study designed a model of teaching reading for university EFL students based on the English curriculum at the Faculty of Languages and Literature and the concept of the team-based learning in order to improve the reading comprehension of the students. What kind of teaching model can help students to improve their reading comprehension? The…

  10. 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

  11. A minimal cascade model for the mitotic oscillator involving cyclin and cdc2 kinase.

    PubMed Central

    Goldbeter, A

    1991-01-01

    A minimal model for the mitotic oscillator is presented. The model, built on recent experimental advances, is based on the cascade of post-translational modification that modulates the activity of cdc2 kinase during the cell cycle. The model pertains to the situation encountered in early amphibian embryos, where the accumulation of cyclin suffices to trigger the onset of mitosis. In the first cycle of the bicyclic cascade model, cyclin promotes the activation of cdc2 kinase through reversible dephosphorylation, and in the second cycle, cdc2 kinase activates a cyclin protease by reversible phosphorylation. That cyclin activates cdc2 kinase while the kinase triggers the degradation of cyclin has suggested that oscillations may originate from such a negative feedback loop [Félix, M. A., Labbé, J. C., Dorée, M., Hunt, T. & Karsenti, E. (1990) Nature (London) 346, 379-382]. This conjecture is corroborated by the model, which indicates that sustained oscillations of the limit cycle type can arise in the cascade, provided that a threshold exists in the activation of cdc2 kinase by cyclin and in the activation of cyclin proteolysis by cdc2 kinase. The analysis shows how miototic oscillations may readily arise from time lags associated with these thresholds and from the delayed negative feedback provided by cdc2-induced cyclin degradation. A mechanism for the origin of the thresholds is proposed in terms of the phenomenon of zero-order ultrasensitivity previously described for biochemical systems regulated by covalent modification. PMID:1833774

  12. 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…

  13. SWIFT: a dynamical model of saccade generation during reading.

    PubMed

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

    2005-10-01

    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 observed in reading experiments. The authors present an advanced version of SWIFT that integrates properties of the oculomotor system and effects of word recognition to explain many of the experimental phenomena faced in reading research. They propose new procedures for the estimation of model parameters and for the test of the model's performance. They also present a mathematical analysis of the dynamics of the SWIFT model. Finally, within this framework, they present an analysis of the transition from parallel to serial processing. PMID:16262468

  14. 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.

  15. An equivalent circuit model for terahertz quantum cascade lasers: Modeling and experiments

    NASA Astrophysics Data System (ADS)

    Yao, Chen; Xu, Tian-Hong; Wan, Wen-Jian; Zhu, Yong-Hao; Cao, Jun-Cheng

    2015-09-01

    Terahertz quantum cascade lasers (THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model. Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339803), the National High Technology Research and Development Program of China (Grant No. 2011AA010205), the National Natural Science Foundation of China (Grant Nos. 61131006, 61321492, and 61404149), the Major National Development Project of Scientific Instrument and Equipment, China (Grant No. 2011YQ150021), the National Science and Technology Major Project, China (Grant No. 2011ZX02707), the Major Project, China (Grant No. YYYJ-1123-1), the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciences, and the Shanghai Municipal Commission of Science and Technology, China (Grant Nos. 14530711300).

  16. 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. PMID:26111404

  17. Effects of temporal correlations on cascades: Threshold models on temporal networks

    NASA Astrophysics Data System (ADS)

    Backlund, Ville-Pekka; Saramäki, Jari; Pan, Raj Kumar

    2014-06-01

    A person's decision to adopt an idea or product is often driven by the decisions of peers, mediated through a network of social ties. A common way of modeling adoption dynamics is to use threshold models, where a node may become an adopter given a high enough rate of contacts with adopted neighbors. We study the dynamics of threshold models that take both the network topology and the timings of contacts into account, using empirical contact sequences as substrates. The models are designed such that adoption is driven by the number of contacts with different adopted neighbors within a chosen time. We find that while some networks support cascades leading to network-level adoption, some do not: the propagation of adoption depends on several factors from the frequency of contacts to burstiness and timing correlations of contact sequences. More specifically, burstiness is seen to suppress cascade sizes when compared to randomized contact timings, while timing correlations between contacts on adjacent links facilitate cascades.

  18. Modeling elephant-mediated cascading effects of water point closure.

    PubMed

    Hilbers, Jelle P; Van Langevelde, Frank; Prins, Herbert H T; Grant, C C; Peel, Mike J S; Coughenour, Michael B; De Knegt, Henrik J; Slotow, Rob; Smit, Izak P J; Kiker, Greg A; De Boer, Willem F

    2015-03-01

    Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are, however, alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested in order to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in availability of artificial WPs; levels of natural water; and elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of meso-mixed feeders, meso-browsers, and some meso-grazers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Under dry conditions, the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years, and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically

  19. Confronting Galactic center and dwarf spheroidal gamma-ray observations with cascade annihilation models

    NASA Astrophysics Data System (ADS)

    Dutta, Bhaskar; Gao, Yu; Ghosh, Tathagata; Strigari, Louis E.

    2015-10-01

    Many particle dark matter models predict that the dark matter undergoes cascade annihilations, i.e. the annihilation products are 4-body final states. In the context of model-independent cascade annihilation processes, we study the compatibility of the dark matter interpretation of the Fermi-LAT Galactic center gamma-ray emission with null detections from dwarf spheroidal galaxies. For canonical values of the Milky Way density profile and the local dark matter density, we find that the dark matter interpretation to the Galactic center emission is strongly constrained. However, uncertainties in the dark matter distribution weaken the constraints and leave open dark matter interpretations over a wide range of mass scales.

  20. A Simple Model of Cross-Field Diffusion in Hall Thrusters based on Turbulence Energy Cascade

    NASA Astrophysics Data System (ADS)

    Cappelli, Mark A.; Cha, Eunsun; Fernandez, Eduardo

    2014-10-01

    We present a Hall plasma thruster model based on turbulence energy cascade to smaller scales characterized by the electrons gyro-radius. We employ scaling arguments originally developed for viscous energy dissipation in turbulent fluid mechanics with the assumption that the electron scattering rate is expected to scale as the strain-rate in the electron fluid, and that the size of the largest turbulent eddies scale as the electron gyro-radius and local drift velocity. Using this framework, expressions are derived for the entropy production rate which can be used in an independent entropy transport equation from which the transport coefficient can be derived. Alternatively, if one assumes that the main source of electron energy dissipation is turbulent energy cascade, then the energy dissipation replaces the Ohmic heating term in the electron energy equation. We will present the general results of this analysis, as well as initial results obtained from 2-D hybrid simulations that incorporate this model and its variants.

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

    DOE PAGESBeta

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; Weber, William J.

    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 e ects 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 inmore » Ni.« less

  2. From child maltreatment to adolescent cannabis abuse and dependence: A developmental cascade model

    PubMed Central

    Rogosch, Fred A.; Oshri, Assaf; Cicchetti, Dante

    2010-01-01

    A developmental cascade model tested associations among child maltreatment, internalizing and externalizing psychopathology, social competence, and cannabis abuse and dependence symptoms in a longitudinal cohort (N = 415). Nested structural equation models evaluated continuity and cross-domain influences among broad multi-informant constructs across four developmental periods: age 7 to 9, 10 to 12, 13 to 15, and 15 to 18. Results indicated significant paths from child maltreatment to early externalizing and internalizing problems and social competence, as well as to cannabis abuse and dependence (CAD) symptoms in adolescence. Youth CAD symptoms were primarily related directly to child maltreatment and externalizing problems. Childhood internalizing symptoms contributed to later childhood decreases in social competence, which predicted increases in late adolescent externalizing problems. Using a developmental psychopathology framework, results are discussed in relation to cascade and transactional effects and the interplay between problem behaviors during childhood and development of CAD symptoms during early and late adolescence. PMID:20883588

  3. “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

  4. 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. PMID:17677162

  5. 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.

  6. 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).…

  7. Modeling Snowcover Sensitivity to Warming Temperature Across a Climatic Gradient in the Oregon Cascades

    NASA Astrophysics Data System (ADS)

    Cooper, M. G.; Sproles, E.; Nolin, A. W.; Rittger, K. E.; Painter, T. H.

    2013-12-01

    Warming winter temperatures will continue to shift precipitation from snow to rain, decreasing mountain snowpacks in temperature-sensitive regions such as the Pacific Northwest. Snow in the Oregon Cascades is particularly at risk because it falls at temperatures close to the melting point. The west side of the Oregon Cascades receives significantly more winter precipitation than the east side (2000 mm vs. 600 mm). While previous studies have focused on the west side of the Oregon Cascades, to date, no study has examined effects of warming temperature on snow over both the east and west sides of this mountain range. This study examines the effect of warming temperatures on present day and future patterns of snowpack accumulation and ablation in the headwater catchments of McKenzie (west side) and Metolius (east side) River Basins of the Oregon Cascades. This study employs a process-based, spatially distributed model, SnowModel, to quantify snow accumulation and ablation. We run the model at 100-m spatial scale on a daily time step, driving the model using spatially distributed meteorological data from stations in and around the sub-basins. The modeling period covers 1989-2009, during which time the region experienced high, low, and average snow water equivalent (SWE). For each basin, we quantify the date and magnitude of peak SWE, the date of snow disappearance, the ratio of SWE to winter precipitation (SWE:P), and the snow-covered area (SCA) at peak SWE for each year. We validate our model results using available SWE measurements and snow extent from Landsat remote sensing imagery. SnowModel is then run using perturbed meteorological input data (+1°C, +2°C, +3°C, +4°C and ×10% precipitation) to evaluate the potential effects of a warmer, wetter/drier winter climate on snowpack accumulation and melt in the watersheds. Simulations of SWE, precipitation, and temperature in the McKenzie Basin for the study period have Nash-Sutcliffe efficiencies of 0.83, 0.97, and

  8. 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…

  9. 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)

  10. 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…

  11. Monte Carlo Modeling of Cascade Gamma Rays in 86Y PET imaging: Preliminary results

    PubMed Central

    Zhu, Xuping; El Fakhri, Georges

    2011-01-01

    86Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in 90Y radionuclide therapy. However, 86Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET 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), singles and coincidences statistics and detected photons energy distribution within the PET energy window. A 20% discrepancy 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 for 86Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize 86Y PET. Compared with conventional 18F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in 86Y 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 86Y PET. PMID:19521011

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

    NASA Astrophysics Data System (ADS)

    Zhu, Xuping; El Fakhri, Georges

    2009-07-01

    86Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in 90Y radionuclide therapy. However, 86Y 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 86Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize 86Y PET. Compared with conventional 18F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in 86Y 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 86Y PET.

  13. 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.

  14. 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. PMID:22183193

  15. 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.

  16. How to generate continuous cascade models with zero values: theory and simulations for a continuous beta-multifractal model

    NASA Astrophysics Data System (ADS)

    Schmitt, F. G.

    2014-12-01

    Multiplicative cascade models, when densified (continuous scale invariance) correspond to the exponential of a linear process. Hence this cannot generate zero values. Such framework is not complete and not purely multiplicative. We present here a stochastic framework which stays in the multiplicative realm and can be used to generate zero values. The multiplicative continuous model for multifractal fields with zero values is built using infinitely multiplicative random variables, the multiplicative analog to infinitely divisible distributions for addition. It also needs stochastic multiplicative measures and multiplicative stochastic integrals. The model hence generates continuous multiplicative cascades. The model produced possesses as special case a continuous generalization of the classical discrete beta-model. Applications are numerous in many fields of applied sciences, including smallscale rainfall, soil sciences. The theory is first proposed, then simulation algorithm is presented and simulations are shown in 1D and in 2D. Figure: a continuous lognormal multifractal with zero values (512x512).

  17. 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.

  18. A cascade model of information processing and encoding for retinal prosthesis.

    PubMed

    Pei, Zhi-Jun; Gao, Guan-Xin; Hao, Bo; Qiao, Qing-Li; Ai, Hui-Jian

    2016-04-01

    Retinal prosthesis offers a potential treatment for individuals suffering from photoreceptor degeneration diseases. Establishing biological retinal models and simulating how the biological retina convert incoming light signal into spike trains that can be properly decoded by the brain is a key issue. Some retinal models have been presented, ranking from structural models inspired by the layered architecture to functional models originated from a set of specific physiological phenomena. However, Most of these focus on stimulus image compression, edge detection and reconstruction, but do not generate spike trains corresponding to visual image. In this study, based on state-of-the-art retinal physiological mechanism, including effective visual information extraction, static nonlinear rectification of biological systems and neurons Poisson coding, a cascade model of the retina including the out plexiform layer for information processing and the inner plexiform layer for information encoding was brought forward, which integrates both anatomic connections and functional computations of retina. Using MATLAB software, spike trains corresponding to stimulus image were numerically computed by four steps: linear spatiotemporal filtering, static nonlinear rectification, radial sampling and then Poisson spike generation. The simulated results suggested that such a cascade model could recreate visual information processing and encoding functionalities of the retina, which is helpful in developing artificial retina for the retinally blind. PMID:27212929

  19. A cascade model of information processing and encoding for retinal prosthesis

    PubMed Central

    Pei, Zhi-jun; Gao, Guan-xin; Hao, Bo; Qiao, Qing-li; Ai, Hui-jian

    2016-01-01

    Retinal prosthesis offers a potential treatment for individuals suffering from photoreceptor degeneration diseases. Establishing biological retinal models and simulating how the biological retina convert incoming light signal into spike trains that can be properly decoded by the brain is a key issue. Some retinal models have been presented, ranking from structural models inspired by the layered architecture to functional models originated from a set of specific physiological phenomena. However, Most of these focus on stimulus image compression, edge detection and reconstruction, but do not generate spike trains corresponding to visual image. In this study, based on state-of-the-art retinal physiological mechanism, including effective visual information extraction, static nonlinear rectification of biological systems and neurons Poisson coding, a cascade model of the retina including the out plexiform layer for information processing and the inner plexiform layer for information encoding was brought forward, which integrates both anatomic connections and functional computations of retina. Using MATLAB software, spike trains corresponding to stimulus image were numerically computed by four steps: linear spatiotemporal filtering, static nonlinear rectification, radial sampling and then Poisson spike generation. The simulated results suggested that such a cascade model could recreate visual information processing and encoding functionalities of the retina, which is helpful in developing artificial retina for the retinally blind. PMID:27212929

  20. 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…

  1. 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. PMID:24315376

  2. 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

  3. 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

  4. 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.

  5. The Short Circuit Model of Reading.

    ERIC Educational Resources Information Center

    Lueers, Nancy M.

    The name "short circuit" has been given to this model because, in many ways, it adequately describes what happens bioelectrically in the brain. The "short-circuiting" factors include linguistic, sociocultural, attitudinal and motivational, neurological, perceptual, and cognitive factors. Research is reviewed on ways in which each one affects any…

  6. Model Programs: Reading. The Topeka Reading Clinic, Centers, and Services, Topeka, Kansas.

    ERIC Educational Resources Information Center

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

    The Topeka Reading Clinic, Centers, and Services provides help for disabled readers in the Topeka, Kansas, elementary and junior high schools. The professional staff of the clinic diagnoses reading disabilities and designs remedial programs. The remedial reading teachers affiliated with the clinic offer reading classes in the schools for grade 4…

  7. 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…

  8. Propagation of hydro-meteorological uncertainty in a model cascade framework to inundation prediction

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rincón, J. P.; Pedrozo-Acuña, A.; Breña-Naranjo, J. A.

    2015-07-01

    This investigation aims to study the propagation of meteorological uncertainty within a cascade modelling approach to flood prediction. The methodology was comprised of a numerical weather prediction (NWP) model, a distributed rainfall-runoff model and a 2-D hydrodynamic model. The uncertainty evaluation was carried out at the meteorological and hydrological levels of the model chain, which enabled the investigation of how errors that originated in the rainfall prediction interact at a catchment level and propagate to an estimated inundation area and depth. For this, a hindcast scenario is utilised removing non-behavioural ensemble members at each stage, based on the fit with observed data. At the hydrodynamic level, an uncertainty assessment was not incorporated; instead, the model was setup following guidelines for the best possible representation of the case study. The selected extreme event corresponds to a flood that took place in the southeast of Mexico during November 2009, for which field data (e.g. rain gauges; discharge) and satellite imagery were available. Uncertainty in the meteorological model was estimated by means of a multi-physics ensemble technique, which is designed to represent errors from our limited knowledge of the processes generating precipitation. In the hydrological model, a multi-response validation was implemented through the definition of six sets of plausible parameters from past flood events. Precipitation fields from the meteorological model were employed as input in a distributed hydrological model, and resulting flood hydrographs were used as forcing conditions in the 2-D hydrodynamic model. The evolution of skill within the model cascade shows a complex aggregation of errors between models, suggesting that in valley-filling events hydro-meteorological uncertainty has a larger effect on inundation depths than that observed in estimated flood inundation extents.

  9. Extended Intranuclear Cascade model for pickup reactions induced by 50-MeV-range protons

    NASA Astrophysics Data System (ADS)

    Uozumi, Yusuke; Mori, Taiki; Sonoda, Akifumi; Nakano, Masahiro

    2016-06-01

    The intranuclear cascade model was investigated to explain (p, dx) and (p, ax) reactions at incident energies of around 50 MeV. Since these reactions are governed mainly by the direct pickup process, the model was expanded to include exclusive pickup processes leading to hole-state-excitations. The energy of the outgoing clusters is determined with single-particle energies of transferred nucleons, the reaction Q-value, and the recoil of the residual nucleus. The rescattering of the produced cluster inside the nucleus is treated within the intranuclear cascade model. The emission angle is given by the sum of momentum vectors of transferred nucleons in addition to the deflection at the nuclear surface, which was introduced to explain angular distributions of elastic scattering. Double differential cross sections of reactions were calculated and compared with experimental data. The proposed model showed a high predictive power over the wide range of emission energies and angles. The treatment ofthe cluster transport inside the nucleus was also verified.

  10. CASCADER: An M-chain gas-phase radionuclide transport and fate model

    SciTech Connect

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

    1993-02-01

    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 diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one-space dimensional transport and fate model for M-chain radionuclides in very dry homogeneous or heterogeneous soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advection velocity is derived from an embedded air-pumping submodel. The air-pumping submodel is based on an assumption of isothermal conditions, which is driven by barometric pressure. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions are used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77.

  11. Modulation transfer function cascade model for a sampled IR imaging system.

    PubMed

    de Luca, L; Cardone, G

    1991-05-01

    The performance of the infrared scanning radiometer (IRSR) is strongly stressed in convective heat transfer applications where high spatial frequencies in the signal that describes the thermal image are present. The need to characterize more deeply the system spatial resolution has led to the formulation of a cascade model for the evaluation of the actual modulation transfer function of a sampled IR imaging system. The model can yield both the aliasing band and the averaged modulation response for a general sampling subsystem. For a line scan imaging system, which is the case of a typical IRSR, a rule of thumb that states whether the combined sampling-imaging system is either imaging-dependent or sampling-dependent is proposed. The model is tested by comparing it with other noncascade models as well as by ad hoc measurements performed on a commercial digitized IRSR. PMID:20700340

  12. Toward a Tripartite Model of L2 Reading Strategy Use, Motivations, and Learner Beliefs

    ERIC Educational Resources Information Center

    Matsumoto, Hiroyuki; Hiromori, Tomohito; Nakayama, Akira

    2013-01-01

    The present study proposes a tripartite model of L2 reading strategy use, reading motivations, and general learner beliefs by examining the relationships among them in an L2 context. Reading strategy instruction was performed for 360 first-year university students enrolled in a reading-based course, in expectation of affecting their motivations…

  13. 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…

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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-ɛ 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 106 A/m2. The pressure inside the arc varies from 105 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.

  15. 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.

  16. Modeling vibroacoustic systems involving cascade open cavities and micro-perforated panels.

    PubMed

    Yu, Xiang; Cheng, Li; Guyader, Jean-Louis

    2014-08-01

    While the structural-acoustic coupling between flexible structures and closed acoustic cavities has been extensively studied in the literature, the modeling of structures coupled through open cavities, especially connected in cascade, is still a challenging task for most of the existing methods. The possible presence of micro-perforated panels (MPPs) in such systems adds additional difficulties in terms of both modeling and physical understanding. In this study, a sub-structuring methodology based on the Patch Transfer Function (PTF) approach with a Compound Interface treatment technique, referred to as CI-PTF method, is proposed, for dealing with complex systems involving cascade open/closed acoustic cavities and MPPs. The co-existence of apertures and solid/flexible/micro-perforated panels over a mixed separation interface is characterized using a compound panel subsystem, which enhances the systematic coupling feature of the PTF framework. Using several typical configurations, the versatility and efficiency of the proposed method is illustrated. Numerical studies highlight the physical understanding on the behavior of MPP inside a complex vibroacoustic environment, thus providing guidance for the practical design of such systems. PMID:25096101

  17. 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

  18. Testing a developmental cascade model of emotional and social competence and early peer acceptance

    PubMed Central

    Blandon, Alysia Y.; Calkins, Susan D.; Grimm, Kevin J.; Keane, Susan P.; O’Brien, Marion

    2011-01-01

    A developmental cascade model of early emotional and social competence predicting later peer acceptance was examined in a community sample of 440 children across the ages of 2 to 7. Children’s externalizing behavior, emotion regulation, social skills within the classroom and peer acceptance were examined utilizing a multitrait-multimethod approach. A series of longitudinal cross-lag models that controlled for shared rater variance were fit using structural equation modeling. Results indicated there was considerable stability in children’s externalizing behavior problems and classroom social skills over time. Contrary to expectations, there were no reciprocal influences between externalizing behavior problems and emotion regulation, though higher levels of emotion regulation were associated with decreases in subsequent levels of externalizing behaviors. Finally, children’s early social skills also predicted later peer acceptance. Results underscore the complex associations among emotional and social functioning across early childhood. PMID:20883578

  19. An upgraded issue of the parton and hadron cascade model, PACIAE 2.2

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The parton and hadron cascade model PACIAE 2.1 (cf. Comput. Phys. Commun. 184 (2013) 1476) has been upgraded to the new issue of PACIAE 2.2. By this new issue the lepton-nucleon and lepton-nucleus (inclusive) deep inelastic scatterings can also be investigated. As an example, the PACIAE 2.2 model is enabled to calculate the specific charged hadron multiplicity in the e-+p and e-+D semi-inclusive deep-inelastic scattering at 27.6 GeV electron beam energy. The calculated results are well comparing with the corresponding HERMES data. Additionally, the effect of model parameters α and β in the Lund string fragmentation function on the multiplicity is studied.

  20. Enhanced modeling of band nonparabolicity with application to a mid-IR quantum cascade laser structure

    NASA Astrophysics Data System (ADS)

    Vukovic, N.; Radovanovic, J.; Milanovic, V.

    2014-09-01

    We analyze the influence of conduction-band nonparabolicity on bound electronic states in the active region of a quantum cascade laser (QCL). Our model assumes expansion of the conduction-band dispersion relation up to a fourth order in wavevector and use of a suitable second boundary condition at the interface of two III-V semiconductor layers. Numerical results, obtained by the transfer matrix method, are presented for two mid-infrared GaAs/Al0.33Ga0.67As QCL active regions, and they are in very good agreement with experimental data found in the literature. Comparison with a different nonparabolicity model is presented for the example of a GaAs/Al0.38Ga0.62As-based mid-IR QCL. Calculations have also been carried out for one THz QCL structure to illustrate the possible application of the model in the terahertz part of the spectrum.

  1. Components of Reading Ability: Multivariate Evidence for a Convergent Skills Model of Reading Development

    ERIC Educational Resources Information Center

    Vellutino, Frank R.; Tunmer, William E.; Jaccard, James J.; Chen, RuSan

    2007-01-01

    Elementary and middle school children were given a large battery of tests evaluating reading subskills and reading-related cognitive abilities. These measures were used to define latent representing skills and abilities believed to be important components of reading comprehension. Hypothesized relationships among these constructs were specified…

  2. The cascade of uncertainty in modeling the impacts of climate change on Europe's forests

    NASA Astrophysics Data System (ADS)

    Reyer, Christopher; Lasch-Born, Petra; Suckow, Felicitas; Gutsch, Martin

    2015-04-01

    Projecting the impacts of global change on forest ecosystems is a cornerstone for designing sustainable forest management strategies and paramount for assessing the potential of Europe's forest to contribute to the EU bioeconomy. Research on climate change impacts on forests relies to a large extent on model applications along a model chain from Integrated Assessment Models to General and Regional Circulation Models that provide important driving variables for forest models. Or to decision support systems that synthesize findings of more detailed forest models to inform forest managers. At each step in the model chain, model-specific uncertainties about, amongst others, parameter values, input data or model structure accumulate, leading to a cascade of uncertainty. For example, climate change impacts on forests strongly depend on the in- or exclusion of CO2-effects or on the use of an ensemble of climate models rather than relying on one particular climate model. In the past, these uncertainties have not or only partly been considered in studies of climate change impacts on forests. This has left managers and decision-makers in doubt of how robust the projected impacts on forest ecosystems are. We deal with this cascade of uncertainty in a structured way and the objective of this presentation is to assess how different types of uncertainties affect projections of the effects of climate change on forest ecosystems. To address this objective we synthesized a large body of scientific literature on modeled productivity changes and the effects of extreme events on plant processes. Furthermore, we apply the process-based forest growth model 4C to forest stands all over Europe and assess how different climate models, emission scenarios and assumptions about the parameters and structure of 4C affect the uncertainty of the model projections. We show that there are consistent regional changes in forest productivity such as an increase in NPP in cold and wet regions while

  3. Time to smell: a cascade model of human olfactory perception based on response-time (RT) measurement

    PubMed Central

    Olofsson, Jonas K.

    2014-01-01

    The timing of olfactory behavioral decisions may provide an important source of information about how the human olfactory-perceptual system is organized. This review integrates results from olfactory response-time (RT) measurements from a perspective of mental chronometry. Based on these findings, a new cascade model of human olfaction is presented. Results show that main perceptual decisions are executed with high accuracy within about 1~s of sniff onset. The cascade model proposes the existence of distinct processing stages within this brief time-window. According to the cascade model, different perceptual features become accessible to the perceiver at different time-points, and the output of earlier processing stages provides the input for later processing stages. The olfactory cascade starts with detecting the odor, which is followed by establishing an odor object. The odor object, in turn, triggers systems for determining odor valence and edibility. Evidence for the cascade model comes from studies showing that RTs for odor valence and edibility assessment are predicted by the shorter RTs needed to establish the odor object. Challenges for future research include innovative task designs for olfactory RT experiments and the integration of the behavioral processing sequence into the underlying cortical processes using complementary RT measures and neuroimaging methods. PMID:24550861

  4. 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. PMID:20836598

  5. 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…

  6. 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…

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

    DOE PAGESBeta

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

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Béland, L. K.; Stocks, G. M.; Stoller, R. E.

    2016-05-01

    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.

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

    PubMed

    Samolyuk, G D; Béland, L K; Stocks, G M; Stoller, R E

    2016-05-01

    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. PMID:27033732

  10. Transonic viscous flow calculations for a turbine cascade with a two equation turbulence model

    NASA Technical Reports Server (NTRS)

    Boretti, A. A.

    1989-01-01

    A numerical method for the study of steady, transonic, turbulent viscous flow through plane turbine cascades is presented. The governing equations are written in Favre-averaged form and closed with a first order model. The turbulent quantities are expressed according to a two-equation kappa-epsilon model where low Reynolds number and compressibility effects are included. The solution is obtained by using a pseudo-unsteady method with improved perturbation propagation properties. The equations are discretized in space by using a finite volume formulation. An explicit multistage dissipative Runge-Kutta algorithm is then used to advance the flow equations in the pseudo-time. First results of calculations compare fairly well with experimental data.

  11. Eating and digesting "Lestrygonians": a physiological model of reading.

    PubMed

    Yared, Aida

    2008-01-01

    In this article, I propose that, beneath a deceptively simple story-line, "Lestrygonians" functions like a living entity, one through which Bloom unknowingly traverses. First, there is Joyce's familiar Dublin, on a macroscopic level, and, second, there is the episode's narrative, personified by a gigantic female organism, in whose digestive tract Bloom has been reduced to Lilliputian size. Some critics have noted the importance of the physiological details of digestion here; no one, however, has noted to what extent the structure of the episode is represented by the digestive model. My final claim about the episode's digestive proclivities concerns its effects on the reader. If "Lestrygonians" replicates alimentary functions by propelling both its characters and the reading process along, it also elicits, in the reader, the synesthesia of reading with autonomic sensations. PMID:20836271

  12. Evaluation of random cascade hierarchical and statistical arrangement model in disaggregation of SMOS soil moisture

    NASA Astrophysics Data System (ADS)

    Hosseini, M.; Magagi, R.; Goita, K.

    2013-12-01

    Soil moisture is an important parameter in hydrology that can be derived from remote sensing. In different studies, it was shown that optical-thermal, active and passive microwave remote sensing data can be used for soil moisture estimation. However, the most promising approach to estimate soil moisture in large areas is passive microwave radiometry. Global estimation of soil moisture is now operational by using remote sensing techniques. The Advanced Microwave Scanning Radiometer-Earth Observing System Sensor (AMSR-E) and Soil Moisture and Ocean Salinity (SMOS) passive microwave radiometers that were lunched on 2002 and 2009 respectively along with the upcoming Soil Moisture Active-Passive (SMAP) satellite that was planned to be lunched in the time frame of 2014-2015 make remote sensing to be more useful in soil moisture estimation. However, the spatial resolutions of AMSR-E, SMOS and SMAP are 60 km, 40 km and 10 km respectively. These very low spatial resolutions can not show the temporal and spatial variability of soil moisture in field or small scales. So, using disaggregation methods is required to efficiently using the passive microwave derived soil moisture information in different scales. The low spatial resolutions of passive microwave satellites can be improved by using disaggregation methods. Random Cascade (RC) model (Over and Gupta, 1996) is used in this research to downscale the 40 km resolution of SMOS satellite. By using this statistical method, the SMOS soil moisture resolutions are improved to 20 km, 10 km, 5 km and 2.5 km, respectively. The data that were measured during Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) field campaign are used to do the experiments. Totally the ground data and SMOS images that were obtained during 13 different days from 7-June-2012 to 13-July-2012 are used. By comparison with ground soil moisture, it is observed that the SMOS soil moisture is underestimated for all the images and so bias amounts

  13. Nelder-Mead simplex method for modeling of cascaded continuous-wave multiple-Stokes Raman fiber lasers

    NASA Astrophysics Data System (ADS)

    Tse, Chun Ho; Tang, Ming; Shum, Perry Ping; Wu, Rui Fen

    2010-09-01

    We propose and demonstrate an effective and computationally compact Nelder-Mead simplex method for the design and modeling of cw cascaded Raman fiber lasers. The Nelder-Mead method is efficient for finding a local minimum of a function of several variables. We employ this classical powerful local descent algorithm to solve the multidimensional problem for the modeling of n'th-order cascaded Raman fiber lasers. With our proposed method, we investigate a linear cascaded Raman fiber laser with a pump wavelength of 1064 nm. The convergence of the proposed method solving the rate equations with boundary conditions is easily and correctly achieved. Our simulation results verify that the proposed method has good computational speed without losing simulation accuracy.

  14. Sequenced Contractions and Abbreviations for Model 2 Reading.

    ERIC Educational Resources Information Center

    Cronnell, Bruce

    The nature and use of contractions and abbreviations in beginning reading is discussed and applied to the Southwest Regional Laboratory (SWRL) Mod 2 Reading Program, a four-year program (K-3) for teaching reading skills to primary-grade children. The contractions and abbreviations are listed and sequenced for the reading program. The results of…

  15. Impaired Oral Reading in Two Atypical Dyslexics: A Comparison with a Computational Lexical-Analogy Model

    ERIC Educational Resources Information Center

    Marchand, Y.; Friedman, R.B.

    2005-01-01

    A computational model of reading was developed based upon the notion that the structural relationship between orthography and phonology is of greater importance than the dimension of semantics for the reading aloud of single words. Degradation of this model successfully simulated the reading performance of two patients with atypical acquired…

  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. 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.

  18. 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…

  19. A Prediction Model of Foreign Language Reading Proficiency Based on Reading Time and Text Complexity

    ERIC Educational Resources Information Center

    Kotani, Katsunori; Yoshimi, Takehiko; Isahara, Hitoshi

    2010-01-01

    In textbooks, foreign (second) language reading proficiency is often evaluated through comprehension questions. In case, authentic texts are used as reading material, such questions should be prepared by teachers. However, preparing appropriate questions may be a very demanding task for teachers. This paper introduces a method for automatically…

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Genetic and Environmental Bases of Reading and Spelling: A Unified Genetic Dual Route Model

    ERIC Educational Resources Information Center

    Bates, Timothy C.; Castles, Anne; Luciano, Michelle; Wright, Margaret J.; Coltheart, Max; Martin, Nicholas G.

    2007-01-01

    We develop and test a dual-route model of genetic effects on reading aloud and spelling, based on irregular and non-word reading and spelling performance assessed in 1382 monozygotic and dizygotic twins. As in earlier research, most of the variance in reading was due to genetic effects. However, there were three more specific conclusions: the…

  6. 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…

  7. 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…

  8. Developing new theoretical models of the formation of atomic collision cascades and subcascades in irradiated solids

    SciTech Connect

    Metelkin, E. V.; Ryazanov, A. I. Semenov, E. V.

    2008-09-15

    A new theoretical model is developed for the investigation of atomic collision cascades and subcascades in irradiated solids consisting of atoms of a single type. The model is based on an analytical description of the elastic collisions between moving atoms knocked out of the crystal lattice sites and the immobile atoms of the lattice. The description is based on the linear kinetic Boltzmann equation describing the retardation of primary recoil atoms (PRAs) in irradiated solids. The laws of conservation for the total number and the kinetic energy of moving atoms, which follow from the kinetic Boltzmann equation, are analyzed using the proposed model. An analytical solution is obtained for the stationary kinetic Boltzmann equation, which describes the retardation of PRAs for a given source responsible for their production. A kinetic equation for the moving atoms and the corresponding laws of conservation are also analyzed with allowance for the binding energy of atoms at the crystal lattice sites. A criterion for determining the threshold energy of subcascade formation in irradiated solids is formulated. Based on this criterion, the threshold energy of subcascade formation is calculated using the Thomas-Fermi potential. Formulas are presented for determining the mean size and number of subcascades formed in a solid as functions of the PRA energy.

  9. 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.

  10. 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.

  11. 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…

  12. 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,…

  13. 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

  14. 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…

  15. Model for a pulsed terahertz quantum cascade laser under optical feedback.

    PubMed

    Agnew, Gary; Grier, Andrew; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Ikonić, Zoran; Valavanis, Alexander; Dean, Paul; Cooper, Jonathan; Khanna, Suraj P; Lachab, Mohammad; Linfield, Edmund H; Davies, A Giles; Harrison, Paul; Indjin, Dragan; Rakić, Aleksandar D

    2016-09-01

    Optical feedback effects in lasers may be useful or problematic, depending on the type of application. When semiconductor lasers are operated using pulsed-mode excitation, their behavior under optical feedback depends on the electronic and thermal characteristics of the laser, as well as the nature of the external cavity. Predicting the behavior of a laser under both optical feedback and pulsed operation therefore requires a detailed model that includes laser-specific thermal and electronic characteristics. In this paper we introduce such a model for an exemplar bound-to-continuum terahertz frequency quantum cascade laser (QCL), illustrating its use in a selection of pulsed operation scenarios. Our results demonstrate significant interplay between electro-optical, thermal, and feedback phenomena, and that this interplay is key to understanding QCL behavior in pulsed applications. Further, our results suggest that for many types of QCL in interferometric applications, thermal modulation via low duty cycle pulsed operation would be an alternative to commonly used adiabatic modulation. PMID:27607659

  16. Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model

    NASA Astrophysics Data System (ADS)

    Delmas, C.; Maccario, M.; Croguennec, L.; Le Cras, F.; Weill, F.

    2008-08-01

    Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO4 and FePO4. As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a `domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.

  17. 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

  18. 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.

  19. 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. PMID:27217823

  20. A flare-induced cascade model of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.

    1986-01-01

    An analytical model is developed for the source of gamma ray bursts as a stellar flare in the magnetosphere of a neutron star. It is suggested that the loss of energy through synchrotron radiation experienced by electrons moving through a sufficiently strong magnetic field at a large pitch angle may not be regained. Instead, pulsar theory is applied to show that the acceleration of electrons in an electric field parallel to the magnetic field will rapidly be inhibited by curvature radiation as the loop experiences a reconnection. It is shown that electrons passing through a curvature with a radius of one million with an electric field strength of 10 billion e.s.u. will emit photons with energies of up to 10 to the 12.6 eV by curvature radiation. The photons, gamma rays, would annihilate in the magnetosphere, which they cannot escape. The resulting cascade of electron-positron particles would eventually produce photons of sufficiently low energy to escape. Upper and low bounds are estimated for the resulting emission spectrum, which would vary according to the magnetic field geometry. The model explains the observed 511 keV annihilation line and the optical radiation which at times accompanies gamma-ray bursts.

  1. 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.

  2. Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model.

    PubMed

    Delmas, C; Maccario, M; Croguennec, L; Le Cras, F; Weill, F

    2008-08-01

    Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities. PMID:18641656

  3. Quantum mechanical model of the upper bounds of the cascading contribution to the second hyperpolarizability

    SciTech Connect

    Dawson, Nathan J.; Anderson, Benjamin R.; Schei, Jennifer L.; Kuzyk, Mark G.

    2011-10-15

    Microscopic cascading of second-order nonlinearities between two molecules has been proposed to yield an enhanced third-order molecular nonlinear-optical response. In this contribution, we investigate the two-molecule cascaded second hyperpolarizability and show that it will never exceed the fundamental limit of a single molecule with the same number of electrons as the two-molecule system. We show the apparent divergence behavior of the cascading contribution to the second hyperpolarizability vanishes when properly taking into account the intermolecular interactions. Although cascading can never lead to a larger nonlinear-optical response than a single molecule, it provides alternative molecular design configurations for creating materials with large third-order susceptibilities that may be difficult to design into a single molecule.

  4. Classical model of the upper bounds of the cascading contribution to the second hyperpolarizability

    SciTech Connect

    Dawson, Nathan J.; Anderson, Benjamin R.; Schei, Jennifer L.; Kuzyk, Mark G.

    2011-10-15

    We investigate whether microscopic cascading of second-order nonlinearities of two molecules in the side-by-side configuration can lead to a third-order molecular nonlinear-optical response that exceeds the fundamental limit. We find that for large values of the second hyperpolarizability, the side-by-side configuration has a cascading contribution that lowers the direct contribution. However, we do find that there is a cascading contribution to the second hyperpolarizability when there is no direct contribution. Thus, while cascading can never lead to a larger nonlinear-optical response than for a single molecule with the same number of electrons, it may provide design flexibility in making large third-order susceptibility materials when the molecular second hyperpolarizability vanishes.

  5. 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

  6. 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.

  7. Electromagnetic cascades in the magnetosphere of a very young pulsar - A model for the positron production near the Galactic center

    NASA Technical Reports Server (NTRS)

    Mastichiadis, Apostolos; Brecher, Kenneth; Marscher, Alan P.

    1987-01-01

    A detailed model for positron production by a young pulsar is presented. It is shown that electromagnetic cascades can develop in a young pulsar's magnetosphere, and the model results are applied to the pulsar which is hypothesized to lie near the Galactic center. It is found that such a pulsar would be expected to produce relatively low energy electron-positron pairs with an efficiency rating high enough to explain the observed luminosity of the Galactic center annihilation line. Virtually all of the gamma ray continuum radiation produced in the cascades would be beamed along the magnetic poles of the neutron star, and therefore probably would not be observed from earth. Some observational predictions generated by the proposed model for the Galactic center positron source are given.

  8. 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.

  9. Cascade model of gamma-ray bursts: Power-law and annihilation-line components

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Sturrock, P. A.; Daugherty, J. K.

    1988-01-01

    If, in a neutron star magnetosphere, an electron is accelerated to an energy of 10 to the 11th or 12th power eV by an electric field parallel to the magnetic field, motion of the electron along the curved field line leads to a cascade of gamma rays and electron-positron pairs. This process is believed to occur in radio pulsars and gamma ray burst sources. Results are presented from numerical simulations of the radiation and photon annihilation pair production processes, using a computer code previously developed for the study of radio pulsars. A range of values of initial energy of a primary electron was considered along with initial injection position, and magnetic dipole moment of the neutron star. The resulting spectra was found to exhibit complex forms that are typically power law over a substantial range of photon energy, and typically include a dip in the spectrum near the electron gyro-frequency at the injection point. The results of a number of models are compared with data for the 5 Mar., 1979 gamma ray burst. A good fit was found to the gamma ray part of the spectrum, including the equivalent width of the annihilation line.

  10. 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

  11. 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.

  12. 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…

  13. 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…

  14. Newly Constructed Network Models of Different WNT Signaling Cascades Applied to Breast Cancer Expression Data

    PubMed Central

    Kramer, Frank; Pukrop, Tobias; Beißbarth, Tim; Bleckmann, Annalen

    2015-01-01

    Introduction WNT signaling is a complex process comprising multiple pathways: the canonical β-catenin-dependent pathway and several alternative non-canonical pathways that act in a β-catenin-independent manner. Representing these intricate signaling mechanisms through bioinformatic approaches is challenging. Nevertheless, a simplified but reliable bioinformatic WNT pathway model is needed, which can be further utilized to decipher specific WNT activation states within e.g. high-throughput data. Results In order to build such a model, we collected, parsed, and curated available WNT signaling knowledge from different pathway databases. The data were assembled to construct computationally suitable models of different WNT signaling cascades in the form of directed signaling graphs. This resulted in four networks representing canonical WNT signaling, non-canonical WNT signaling, the inhibition of canonical WNT signaling and the regulation of WNT signaling pathways, respectively. Furthermore, these networks were integrated with microarray and RNA sequencing data to gain deeper insight into the underlying biology of gene expression differences between MCF-7 and MDA-MB-231 breast cancer cell lines, representing weakly and highly invasive breast carcinomas, respectively. Differential genes up-regulated in the MDA-MB-231 compared to the MCF-7 cell line were found to display enrichment in the gene set originating from the non-canonical network. Moreover, we identified and validated differentially regulated modules representing canonical and non-canonical WNT pathway components specific for the aggressive basal-like breast cancer subtype. Conclusions In conclusion, we demonstrated that these newly constructed WNT networks reliably reflect distinct WNT signaling processes. Using transcriptomic data, we shaped these networks into comprehensive modules of the genes implicated in the aggressive basal-like breast cancer subtype and demonstrated that non-canonical WNT signaling is

  15. 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.

  16. 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., Jr.; 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.

  17. Mathematical modelling of a steady flow of a heat conductive incompressible fluid through the cascade of profiles

    NASA Astrophysics Data System (ADS)

    Neustupa, T.

    2016-06-01

    This paper deals with the mathematical model of a steady flow of a heat-conductive incompressible viscous fluid through a spatially periodic plane profile cascade. The corresponding boundary value problem is reduced to one spatial period. We prove the existence of a weak solution of a coupled problem, with various boundary conditions on the parts of the boundary. Particularly, the condition on the outflow is a variant of the so called "do nothing" boundary condition.

  18. Hadronic event generation for hadron cascade calculations and detector simulation, Part IV: The application of the intranuclear cascade model to reactions of pions, nucleons, kaons, and their antiparticles with nuclei below 6 GeV/c

    SciTech Connect

    Haenbssgen, K.

    1987-02-01

    An extension of the intranuclear cascade model is described. The primary hadrons may be pions, kaons, nucleons, and their antiparticles. Secondary particles produced include hyperons or antihyperons. A large amount of experimental data is described by the model. The model is constructed via the Monte Carlo generation of complete events, based on a model of the nucleus structure and the hadron/nucleon interaction inside the nucleus. Calculated average multiplicities and single and double differential cross sections are compared with experimental data.

  19. SPONTANEOUS CURRENT-LAYER FRAGMENTATION AND CASCADING RECONNECTION IN SOLAR FLARES. I. MODEL AND ANALYSIS

    SciTech Connect

    Barta, Miroslav; Buechner, Joerg; Karlicky, Marian; Skala, Jan

    2011-08-10

    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.

  20. 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…

  1. 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…

  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. 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…

  4. Cumulative risk disparities in children's neurocognitive functioning: a developmental cascade model.

    PubMed

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

    2016-03-01

    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 language skills at age 3. We then examined whether this developmental mechanism varied as a function of social risk status. Participants were 501 children recruited when they were newborns, at which point eight psychosocial risk factors were assessed and combined into a metric of cumulative social disadvantage. Families were followed up at 18 months, at which point four social-cognitive skills were assessed using developmentally sensitive tasks: joint attention, empathy, cooperation, and self-recognition. Language was measured at age 3 using a standardized measure of receptive vocabulary. At age 3 and 4.5, EF and ToM were measured using previously validated tasks. Results showed that there were notable cumulative risk disparities in overall neurocognitive skill development, and these effects became more differentiated over time. Support was also found for a developmental mechanism wherein the effect of social cognition at 18 months on ToM and EF in the preschool period operated specifically through children's receptive language ability at age 3. This pathway functioned similarly for children with both low- and high-risk backgrounds. These results extend previous findings by documenting the role of cumulative social disadvantage on children's neurocognition and the pathways that link key neurocognitive abilities across early development. PMID:25845409

  5. 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

  6. Multiple regression analysis of reading performance data from twin pairs with reading difficulties and nontwin siblings: the augmented model.

    PubMed

    Wadsworth, Sally J; Olson, Richard K; Willcutt, Erik G; DeFries, John C

    2012-02-01

    The augmented multiple regression model for the analysis of data from selected twin pairs was extended to facilitate analyses of data from twin pairs and nontwin siblings. Fitting this extended model to data from both selected twin pairs and siblings yields direct estimates of heritability (h2) and the difference between environmental influences shared by members of twin pairs and those of sib or twin-sib pairs (i.e., c2(t) - c2 (s)). When this model was fitted to reading performance data from 293 monozygotic and 436 dizygotic pairs selected for reading difficulties, and 291 of their nontwin siblings, h2 = .48 ± .22, p = .03, and c2 (t) - c2 (s) = .22 ± .12, p = .06. Although the test for differential shared environmental influences is only marginally significant, the results of this analysis suggest that environmental influences on reading performance that are shared by members of twin pairs (.36) may be substantially greater than those for less contemporaneous twin-sibling pairs (.14). PMID:22784461

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

    DOE PAGESBeta

    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

  8. 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. PMID:22293686

  9. 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…

  10. 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…

  11. 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,…

  12. The Prevention Science of Reading Research within a Response-to-Intervention Model

    ERIC Educational Resources Information Center

    Lembke, Erica S.; McMaster, Kristen L.; Stecker, Pamela M.

    2010-01-01

    The purpose of this article is to describe research-based reading intervention within a Response-to-Intervention (RTI) model, using prevention science as a context. First, RTI is defined and a rationale is provided for its use in improving the reading performance of all students, particularly those students identified as at risk for…

  13. Predicting Reading Proficiency in Multilevel Models: An ANOVA-Like Approach of Interpreting Effects

    ERIC Educational Resources Information Center

    Subedi, Bidya Raj

    2007-01-01

    This study used an analysis of variance (ANOVA)-like approach to predict reading proficiency with student, teacher, and school-level predictors based on a 3-level hierarchical generalized linear model (HGLM) analysis. National Assessment of Educational Progress (NAEP) 2000 reading data for 4th graders sampled from 46 states of the United States of…

  14. Ameliorating Reading Disabilities Early: Examining an Effective Encoding and Decoding Prevention Instruction Model

    ERIC Educational Resources Information Center

    Weiser, Beverly L.

    2013-01-01

    The purpose of this study was to determine whether integrating encoding instruction with reading instruction provides stronger gains for students who struggle with reading than instruction that includes little or no encoding. An instructional design model was investigated to best fit the data of 175 first-grade readers at risk for reading…

  15. 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…

  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. Computation of flows in a turn-around duct and a turbine cascade using advanced turbulence models

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, B.; Luo, J.

    1993-01-01

    Numerical investigation has been carried out to evaluate the capability of the Algebraic Reynolds Stress Model (ARSM) and the Nonlinear Stress Model (NLSM) to predict strongly curved turbulent flow in a turn-around duct (TAD). The ARSM includes the near-wall damping term of pressure-strain correlation phi(sub ij,w), which enables accurate prediction of individual Reynolds stress components in wall flows. The TAD mean flow quantities are reasonably well predicted by various turbulence models. The ARSM yields better predictions for both the mean flow and the turbulence quantities than the NLSM and the k-epsilon (k = turbulent kinetic energy, epsilon = dissipation rate of k) model. The NLSM also shows slight improvement over the k-epsilon model. However, all the models fail to capture the recovery of the flow from strong curvature effects. The formulation for phi(sub ij,w) appears to be incorrect near the concave surface. The hybrid k-epsilon/ARSM, Chien's k-epsilon model, and Coakley's q-omega (q = the square root of k, omega = epsilon/k) model have also been employed to compute the aerodynamics and heat transfer of a transonic turbine cascade. The surface pressure distributions and the wake profiles are predicted well by all the models. The k-epsilon model and the k-epsilon/ARSM model provide better predictions of heat transfer than the q-omega model. The k-epsilon/ARSM solutions show significant differences in the predicted skin friction coefficients, heat transfer rates and the cascade performance parameters, as compared to the k-epsilon model. The k-epsilon/ARSM model appears to capture, qualitatively, the anisotropy associated with by-pass transition.

  18. 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…

  19. 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,…

  20. 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…

  1. Corrective Reading Programs, Wichita, Kansas: Model Programs. Childhood Education.

    ERIC Educational Resources Information Center

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

    Prepared for a White House Conference on Children (December 1970), this report describes the Corrective Reading Program of Wichita, supported in target areas by funds from ESEA Title I and considered an effective large-scale remedial program which operates in the public schools. Special classes are held in each school building in which the program…

  2. Developmental Models of Learning to Read Chinese Words

    ERIC Educational Resources Information Center

    Tong, Xiuli; McBride-Chang, Catherine

    2010-01-01

    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…

  3. 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…

  4. 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…

  5. CASCADER: An M-chain gas-phase radionuclide transport and fate model. Volume 3: Heterogeneous layered porous media

    SciTech Connect

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

    1993-02-01

    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 diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one-space dimensional transport and fate model for M-chain radionuclides in very dry homogeneous or heterogeneous soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advection velocity is derived from an embedded air-pumping submodel. The air-pumping submodel is based on an assumption of isothermal conditions, which is driven by barometric pressure. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions are used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77.

  6. CASCADER: An m-chain gas-phase radionuclide transport and fate model. Volume 1, Basic physics and mathematics

    SciTech Connect

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

    1992-06-01

    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 as they are advected and/or dispersed. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one space dimensional transport and fate model for an m-chain of radionuclides in very dry soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advocation velocity is derived from an embedded air-pumping submodel. The airpumping submodel is based on an assumption of isothermal conditions and is barometric pressure driven. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions is used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77.

  7. 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…

  8. The Componential Model of Reading: Predicting First Grade Reading Performance of Culturally Diverse Students from Ecological, Psychological, and Cognitive Factors Assessed at Kindergarten Entry

    ERIC Educational Resources Information Center

    Ortiz, Miriam; Folsom, Jessica S.; Al Otaiba, Stephanie; Greulich, Luana; Thomas-Tate, Shurita; Connor, Carol M.

    2012-01-01

    This study, framed by the component model of reading (CMR), examined the relative importance of kindergarten-entry predictors of first grade reading performance. Specifically, elements within the ecological domain included dialect, maternal education, amount of preschool, and home literacy; elements within the psychological domain included…

  9. Using video self- and peer modeling to facilitate reading fluency in children with learning disabilities.

    PubMed

    Decker, Martha M; Buggey, Tom

    2014-01-01

    The authors compared the effects of video self-modeling and video peer modeling on oral reading fluency of elementary students with learning disabilities. A control group was also included to gauge general improvement due to reading instruction and familiarity with researchers. The results indicated that both interventions resulted in improved fluency. Students in both experimental groups improved their reading fluency. Two students in the self-modeling group made substantial and immediate gains beyond any of the other students. Discussion is included that focuses on the importance that positive imagery can have on student performance and the possible applications of both forms of video modeling with students who have had negative experiences in reading. PMID:22745196

  10. 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.

  11. 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

  12. 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…

  13. Mindless reading revisited: an analysis based on the SWIFT model of eye-movement control.

    PubMed

    Nuthmann, Antje; Engbert, Ralf

    2009-02-01

    In this article, we revisit the mindless reading paradigm from the perspective of computational modeling. In the standard version of the paradigm, participants read sentences in both their normal version as well as the transformed (or mindless) version where each letter is replaced with a z. z-String scanning shares the oculomotor requirements with reading but none of the higher-level lexical and semantic processes. Here we use the z-string scanning task to validate the SWIFT model of saccade generation [Engbert, R., Nuthmann, A., Richter, E., & Kliegl, R. (2005). SWIFT: A dynamical model of saccade generation during reading. Psychological Review, 112(4), 777-813] as an example for an advanced theory of eye-movement control in reading. We test the central assumption of spatially distributed processing across an attentional gradient proposed by the SWIFT model. Key experimental results like prolonged average fixation durations in z-string scanning compared to normal reading and the existence of a string-length effect on fixation durations and probabilities were reproduced by the model, which lends support to the model's assumptions on visual processing. Moreover, simulation results for patterns of regressive saccades in z-string scanning confirm SWIFT's concept of activation field dynamics for the selection of saccade targets. PMID:19026673

  14. 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.

  15. 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.

  16. 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.

  17. Diagnosis and Treatment of Reading Disabilities Based on the Component Model of Reading: An Alternative to the Discrepancy Model of LD

    ERIC Educational Resources Information Center

    Aaron, P. G.; Joshi, R. Malatesha; Gooden, Regina; Bentum, Kwesi E.

    2008-01-01

    Currently, learning disabilities (LD) are diagnosed on the basis of the discrepancy between students' IQ and reading achievement scores. Students diagnosed with LD often receive remedial instruction in resource rooms. The available evidence suggests that the educational policy based on this discrepancy model has not yielded satisfactory results.…

  18. 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…

  19. 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. PMID:22754295

  20. 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.

  1. 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.

  2. The Use of Repeated Reading with Computer Modeling to Promote Reading Fluency with Students Who Have Physical Disabilities

    ERIC Educational Resources Information Center

    Coleman, Mari Beth; Heller, Kathryn Wolff

    2010-01-01

    The ability to read fluently is a critical skill that allows the reader to concentrate on the meaning of the text. It also can contribute to a successful reading experience. However, students with physical disabilities may have difficulty reading fluently due to any number of functional, psychosocial, or environmental factors that can accompany a…

  3. 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…

  4. 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.

  5. 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

  6. Characteristics for two kinds of cascading events

    NASA Astrophysics Data System (ADS)

    Zou, Sheng-Rong; Gu, Ai-Hua; Liu, Ai-Fen; Xu, Xiu-Lian; Wang, Jian; He, Da-Ren

    2011-04-01

    Avalanche or cascade failure is ubiquitous. We first classify the cascading phenomena into two categories: the cascading disasters which result in large-scale functional failures and the cascading events that do not lead to disasters. We elucidate that two important factors, the increasing amount of events and the acceleration of event frequency, can induce the crossover from the cascading phenomenon to the cascading disaster. Through a simplified sandpile model and a heuristic logistic map, we demonstrate that the dependence of the event number on the observation time behaves as a power-law and as an exponential for these two different cascading events, respectively. The analytic derivations are found to be consistent with several empirical observations. Our present findings contribute to the understanding of the transition between different cascading events, providing a basis for the further understanding of the transitions among more general critical events.

  7. A computational modeling of semantic knowledge in reading comprehension: Integrating the landscape model with latent semantic analysis.

    PubMed

    Yeari, Menahem; van den Broek, Paul

    2016-09-01

    It is a well-accepted view that the prior semantic (general) knowledge that readers possess plays a central role in reading comprehension. Nevertheless, computational models of reading comprehension have not integrated the simulation of semantic knowledge and online comprehension processes under a unified mathematical algorithm. The present article introduces a computational model that integrates the landscape model of comprehension processes with latent semantic analysis representation of semantic knowledge. In three sets of simulations of previous behavioral findings, the integrated model successfully simulated the activation and attenuation of predictive and bridging inferences during reading, as well as centrality estimations and recall of textual information after reading. Analyses of the computational results revealed new theoretical insights regarding the underlying mechanisms of the various comprehension phenomena. PMID:27383752

  8. A Model Secondary (6-12) Plan for Reading Intervention and Development: A Response to Requests from Minnesota Schools and Districts to Provide Guidance in Developing Reading Intervention Programs for Secondary Students

    ERIC Educational Resources Information Center

    Ferraro, Jan; Houck, Bonnie; Klund, Sue; Hexum-Platzer, Sharon; Vortman-Smith, Jan

    2006-01-01

    The "Model Secondary (6-12) Plan for Reading Intervention and Development" has been designed to meet the cognitive needs of middle school through high school students whose reading performance ranges from those significantly below expectation through those reading at or above grade level. The reading needs of the population of students in need of…

  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. 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…

  11. 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…

  12. 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

  13. 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.

  14. Aggression, Sibling Antagonism, and Theory of Mind During the First Year of Siblinghood: A Developmental Cascade Model.

    PubMed

    Song, Ju-Hyun; Volling, Brenda L; Lane, Jonathan D; Wellman, Henry M

    2016-07-01

    A developmental cascade model was tested to examine longitudinal associations among firstborn children's aggression, theory of mind (ToM), and antagonism toward their younger sibling during the 1st year of siblinghood. Aggression and ToM were assessed before the birth of a sibling and 4 and 12 months after the birth, and antagonism was examined at 4 and 12 months in a sample of 208 firstborn children (initial Mage  = 30 months, 56% girls) from primarily European American, middle-class families. Firstborns' aggression consistently predicted high sibling antagonism both directly and through poorer ToM. Results highlight the importance of examining longitudinal influences across behavioral, social-cognitive, and relational factors that are closely intertwined even from the early years of life. PMID:27096923

  15. Analysis of read length limiting factors in Pyrosequencing chemistry.

    PubMed

    Mashayekhi, Foad; Ronaghi, Mostafa

    2007-04-15

    Pyrosequencing is a bioluminometric DNA sequencing technique that measures the release of pyrophosphate during DNA synthesis. The amount of pyrophosphate is proportionally converted into visible light by a cascade of enzymatic reactions. Pyrosequencing has heretofore been used for generating short sequence reads (1-100 nucleotides) because certain factors limit the system's ability to perform longer reads accurately. In this study, we have characterized the main read length limiting factors in both three-enzyme and four-enzyme Pyrosequencing systems. A new simulation model was developed to simulate the read length of both systems based on the inhibitory factors in the chemical equations governing each enzymatic cascade. Our results indicate that nonsynchronized extension limits the obtained read length, albeit to a different extent for each system. In the four-enzyme system, nonsynchronized extension due mainly to a decrease in apyrase's efficiency in degrading excess nucleotides proves to be the main limiting factor of read length. Replacing apyrase with a washing step for removal of excess nucleotide proves to be essential in improving the read length of Pyrosequencing. The main limiting factor of the three-enzyme system is shown to be loss of DNA fragments during the washing step. If this loss is minimized to 0.1% per washing cycle, the read length of Pyrosequencing would be well beyond 300 bases. PMID:17343818

  16. Analysis of Read-Length Limiting Factors in Pyrosequencing Chemistry

    PubMed Central

    Mashayekhi, Foad; Ronaghi, Mostafa

    2007-01-01

    Pyrosequencing is a bioluminometric DNA sequencing technique that measures the release of pyrophosphate during DNA synthesis. The amount of pyrophosphate is proportionally converted into visible light by a cascade of enzymatic reactions. Pyrosequencing has thus far been used for generating short sequence reads (1-100 nucleotides), as certain factors limit the system’s ability to accurately perform longer reads. In this study, we have characterized the main read-length limiting factors in both three-enzyme and four-enzyme Pyrosequencing systems. A new simulation model was developed to simulate the read-length of both systems, based on the inhibitory factors in the chemical equations governing each enzymatic cascade. Our results indicate that non-synchronized extension limits the obtained read-length; however, to a different extent for each system. In four-enzyme system, non-synchronized extension due mainly to a decrease in apyrase’s efficiency in degrading excess nucleotides proves to be the main limiting factor of read-length. Replacing apyrase with a washing step for removal of excess nucleotide proves essential in improving the read-length of Pyrosequencing. The main limiting factor of the three-enzyme system is shown to be loss of DNA fragments during the washing step. If this loss is minimized to 0.1% per washing cycle, the read-length of Pyrosequencing would be well beyond 300 bases. PMID:17343818

  17. 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…

  18. 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

  19. 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. PMID:25773984

  20. Mr. Chips 2002: new insights from an ideal-observer model of reading.

    PubMed

    Legge, Gordon E; Hooven, Thomas A; Klitz, Timothy S; Stephen Mansfield, J Stephen; Tjan, Bosco S

    2002-08-01

    The integration of visual, lexical, and oculomotor information is a critical part of reading. Mr. Chips is an ideal-observer model that combines these sources of information optimally to read simple texts in the minimum number of saccades. This model provides a computational framework for interpreting human reading saccades in both normal and low vision. The purpose of this paper is to report performance of the model for conditions emulating reading with normal vision--a visual span of nine characters, multiplicative saccade noise with a standard deviation of 30%, and texts based on three full-length children's books. Comparison of fixation locations by humans and Mr. Chips revealed: (1) that both exhibit very similar word-skipping behavior; (2) both show initial fixations near the center of words, but with a systematic difference suggestive of an asymmetry in the human visual span; and (3) differences in the pattern of refixations within words that may uncover non-optimal lexical inference by human readers. A human context effect--30% difference in mean saccade size between continuous text and random sequences of words--was very similar to the 25% effect for the model associated with a corresponding difference in the predictability of text words. Overall, our findings show that many of the complicated aspects of human reading saccades can be explained concisely by early information-processing constraints. PMID:12207981

  1. Influencing Children's Self-Efficacy and Self-Regulation of Reading and Writing through Modeling

    ERIC Educational Resources Information Center

    Schunk, Dale H.; Zimmerman, Barry J.

    2007-01-01

    According to Bandura's social cognitive theory, self-efficacy and self-regulation are key processes that affect students' learning and achievement. This article discusses students' reading and writing performances using Zimmerman's four-phase social cognitive model of the development of self-regulatory competence. Modeling is an effective means of…

  2. An Evidence-Based Model for Early-Grade Reading Programmes

    ERIC Educational Resources Information Center

    Comings, John P.

    2015-01-01

    This article proposes a model for design of early-grade reading programmes that is based on research and the implementation of research findings. The model has three components: (1) schools should provide instruction in a language their students speak and understand; (2) teachers should employ instruction that is consistent with the current…

  3. Using Visual Models as Pre-Reading Exercises in Teaching Literature.

    ERIC Educational Resources Information Center

    Meeker, Michael W.

    Adapting strategies of invention from the new process-oriented rhetoric, the literature teacher can help students understand what they read through prereading exercises. Presenting students with an abstract model of a text's metaphoric structure, the teacher can spark students' immediate and imaginative response to the model, involving them…

  4. 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…

  5. 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…

  6. 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.

  7. Target fragments in collisions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion nuclei, 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.; Benton, E. V.; Crawford, H. J.

    1995-01-01

    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).

  8. 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

  9. 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.

  10. 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…

  11. 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.

  12. 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…

  13. 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. PMID:21945392

  14. 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.

  15. A Qualitative Study of Motivation to Read for Pleasure with Adolescent Struggling Readers Using a Theoretical Model: How to Begin?

    ERIC Educational Resources Information Center

    Fisher, Gary A.

    2013-01-01

    A mixed method study explored a theoretical model that employed, combined, and added to the theories of self-determination, the reading engagement perspective, and the four-phase model of interest to motivate adolescent struggling readers to read for pleasure. The model adds to the existing body of research because it specifies an instructional…

  16. Task Dependent Lexicality Effects Support Interactive Models of Reading: A Meta-Analytic Neuroimaging Review

    PubMed Central

    McNorgan, Chris; Chabal, Sarah; O’Young, Daniel; Lukic, Sladjana; Booth, James R.

    2015-01-01

    Models of reading must explain how orthographic input activates a phonological representation, and elicits the retrieval of word meaning from semantic memory. Comparisons between tasks that theoretically differ with respect to the degree to which they rely on connections between orthographic, phonological and semantic systems during reading can thus provide valuable insight into models of reading, but such direct comparisons are not well-represented in the literature. An ALE meta-analysis explored lexicality effects directly contrasting words and pseudowords using the lexical decision task and overt or covert naming, which we assume rely most on the semantic and phonological systems, respectively. Interactions between task and lexicality effects demonstrate that different demands of the lexical decision and naming tasks lead to different manifestations of lexicality effects. PMID:25524364

  17. Repeated Reading.

    ERIC Educational Resources Information Center

    Moyer, Sandra B.

    1982-01-01

    The article reviews research on the use of multiple oral rereading (MOR) with reading disabled students. MOR uses daily practice on a selection of little difficulty. Its effectiveness in increasing fluency (accuracy and speed) is examined, and the role of redundancy in three types of reading models is analyzed. (CL)

  18. Activation and quenching of the phototransduction cascade in retinal cones as inferred from electrophysiology and mathematical modeling

    PubMed Central

    Astakhova, Luba; Firsov, Michael

    2015-01-01

    Purpose To experimentally identify and quantify factors responsible for the lower sensitivity of retinal cones compared to rods. Methods Electrical responses of frog rods and fish (Carassius) cones to short flashes of light were recorded using the suction pipette technique. A fast solution changer was used to apply a solution that fixed intracellular Ca2+ concentration at the prestimulus level, thereby disabling Ca2+ feedback, to the outer segment (OS). The results were analyzed with a specially designed mathematical model of phototransduction. The model included all basic processes of activation and quenching of the phototransduction cascade but omitted unnecessary mechanistic details of each step. Results Judging from the response versus intensity curves, Carassius cones were two to three orders of magnitude less sensitive than frog rods. There was a large scatter in sensitivity among individual cones, with red-sensitive cones being on average approximately two times less sensitive than green-sensitive ones. The scatter was mostly due to different signal amplification, since the kinetic parameters of the responses among cones were far less variable than sensitivity. We argue that the generally accepted definition of the biochemical amplification in phototransduction cannot be used for comparing amplification in rods and cones, since it depends on an irrelevant factor, that is, the cell’s volume. We also show that the routinely used simplified parabolic curve fitting to an initial phase of the response leads to a few-fold underestimate of the amplification. We suggest a new definition of the amplification that only includes molecular parameters of the cascade activation, and show how it can be derived from experimental data. We found that the mathematical model with unrestrained parameters can yield an excellent fit to experimental responses. However, the fits with wildly different sets of parameters can be virtually indistinguishable, and therefore cannot

  19. 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.

  20. Stochastic background of atmospheric cascades

    NASA Astrophysics Data System (ADS)

    Wilk, G.; WŁOdarczyk, Z.

    1993-06-01

    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.

  1. 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.

  2. Micro-canonical cascade model: Analyzing parameter changes in the future and their influence on disaggregation results

    NASA Astrophysics Data System (ADS)

    Müller, Hannes; Föt, Annika; Haberlandt, Uwe

    2016-04-01

    Rainfall time series with a high temporal resolution are needed in many hydrological and water resources management fields. Unfortunately, future climate projections are often available only in low temporal resolutions, e.g. daily values. A possible solution is the disaggregation of these time series using information of high-resolution time series of recording stations. Often, the required parameters for the disaggregation process are applied to future climate without any change, because the change is unknown. For this investigation a multiplicative random cascade model is used. The parameters can be estimated directly from high-resolution time series. Here, time series with hourly resolution generated by the ECHAM5-model and dynamically downscaled with the REMO-model (UBA-, BfG- & ENS-realisation) are used for parameter estimation. The parameters are compared between the past (1971-20000), near-term (2021-2050) and long-term future (2071-2100) for temporal resolutions of 1 h and 8 h. Additionally, the parameters of each period are used for the disaggregation of the other two periods. Afterwards the disaggregated time series are analyzed concerning extreme values representation, event specific characteristics (average wet spell duration and amount) and overall time series characteristics (average intensity and fraction of dry spell events). The aim of the investigation is a) to detect and quantify parameter changes and b) to analyze the influence on the disaggregated time series. The investigation area is Lower Saxony, Germany.

  3. Effective screening strategy using ensembled pharmacophore models combined with cascade docking: application to p53-MDM2 interaction inhibitors.

    PubMed

    Xue, Xin; Wei, Jin-Lian; Xu, Li-Li; Xi, Mei-Yang; Xu, Xiao-Li; Liu, Fang; Guo, Xiao-Ke; Wang, Lei; Zhang, Xiao-Jin; Zhang, Ming-Ye; Lu, Meng-Chen; Sun, Hao-Peng; You, Qi-Dong

    2013-10-28

    Protein-protein interactions (PPIs) play a crucial role in cellular function and form the backbone of almost all biochemical processes. In recent years, protein-protein interaction inhibitors (PPIIs) have represented a treasure trove of potential new drug targets. Unfortunately, there are few successful drugs of PPIIs on the market. Structure-based pharmacophore (SBP) combined with docking has been demonstrated as a useful Virtual Screening (VS) strategy in drug development projects. However, the combination of target complexity and poor binding affinity prediction has thwarted the application of this strategy in the discovery of PPIIs. Here we report an effective VS strategy on p53-MDM2 PPI. First, we built a SBP model based on p53-MDM2 complex cocrystal structures. The model was then simplified by using a Receptor-Ligand complex-based pharmacophore model considering the critical binding features between MDM2 and its small molecular inhibitors. Cascade docking was subsequently applied to improve the hit rate. Based on this strategy, we performed VS on NCI and SPECS databases and successfully discovered 6 novel compounds from 15 hits with the best, compound 1 (NSC 5359), K(i) = 180 ± 50 nM. These compounds can serve as lead compounds for further optimization. PMID:24050442

  4. 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.

  5. A Social Interaction Model of Reading. Technical Report No. 218.

    ERIC Educational Resources Information Center

    Bruce, Bertram

    A model for the levels of social interaction between author and reader provides a framework for examining the devices through which the author engages the reader. An important aspect of this model is the creation of additional levels of social interaction involving, for example, an "implied author" and an "implied reader." Newly created characters…

  6. Reading Authentic Texts in a Foreign Language: A Cognitive Model.

    ERIC Educational Resources Information Center

    Swaffar, Janet K.

    1985-01-01

    Suggests there is a need for a new teaching model which will enable second-language students to integrate the formal, cultural, and informational features of the language on which competency is based. This model should be based on the use of authentic texts which reflect the values of the foreign population. (SED)

  7. A Neurally Plausible Parallel Distributed Processing Model of Event-Related Potential Word Reading Data

    PubMed Central

    Laszlo, Sarah; Plaut, David C.

    2011-01-01

    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. PMID:21945392

  8. 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

  9. Merging Ultrasonic Sensor Readings Into A Consistent Environment Model

    NASA Astrophysics Data System (ADS)

    Peremans, Herbert; van Campenhout, Jan M.

    1990-03-01

    The algorithm presented in this paper constructs a geometric model of the environment using ultrasonic sensors. To do this in a reliable way, it has to take different error sources into account. Unlike other approaches, where a low-level, pixel based, probabilistic model is constructed to represent the uncertainty arising from false measurements, a high level, geometric, model is constructed. It is shown that a high level model, besides being faster to construct, is more appropriate for taking into account the typical characteristics of ultrasonic sensors. The algorithm detects and eliminates inconsistent measurements by combining evidence gathered from different points of view. This is made possible by extracting from the measurements not only information concerning the position of obstacles, but also information about regions that must be empty when seen from a certain angle. To conclude, some examples of the behaviour of this algorithm in real-world situations are presented.

  10. Multifractal Analysis of Velocity Vector Fields and a Continuous In-Scale Cascade Model

    NASA Astrophysics Data System (ADS)

    Fitton, G.; Tchiguirinskaia, I.; Schertzer, D.; Lovejoy, S.

    2012-04-01

    the order of 1.5 for all three components. Given we have only the horizontal wind components over a grid for the Germany dataset the comparable probability distributions of horizontal and vertical velocity increments shows the field is isotropic. The Germany dataset allows us to compare the spatial velocity increments with that of the temporal. We briefly mentioned above that the winds in Corsica were subject to vertical forcing effects over large scales. This means the velocity field scaled as 11/5 i.e. Bolgiano-Obukhov instead of Kolmogorov's. To test this we were required to invoke Taylor's frozen turbulence hypothesis since the data was a one point measurement. Having vertical and horizontal velocity increments means we can further justify the claims of an 11/5 scaling law for vertical shears of the velocity and test the validity of the Taylor's hypothesis. We used the results to first simulate the velocity components using continuous in-scale cascades and then discuss the reconstruction of the full vector fields.

  11. 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…

  12. 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…

  13. The Relationship between Victimization at School and Achievement: The Cusp Catastrophe Model for Reading Performance

    ERIC Educational Resources Information Center

    Sideridis, Georgios D.; Antoniou, Faye; Stamovlasis, Dimitrios; Morgan, Paul L.

    2013-01-01

    We evaluated the relationship between victimization and academic achievement from a nonlinear perspective using a cusp catastrophe model. Participants were 62 students with identified learning disabilities (LD) using statewide criteria in Greece. Students participated in a 2-year cohort-sequential design. Reading assessments involved measures of…

  14. Progress Monitoring in Reading: Using Curriculum-Based Measurement in a Response-to-Intervention Model

    ERIC Educational Resources Information Center

    Busch, Todd W.; Reschly, Amy L.

    2007-01-01

    In this article, the authors describe the use of curriculum-based measurement (CBM) reading measures within a response-to-intervention (RTI) framework. They examine the characteristics of the measures to illustrate their technical adequacy for use at each tier in an RTI model. Finally, they look at the use of the measures at Tier 3 (special…

  15. 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…

  16. Is a Three-Tier Reading Intervention Model Associated with Reduced Placement in Special Education?

    ERIC Educational Resources Information Center

    Wanzek, Jeanne; Vaughn, Sharon

    2011-01-01

    Patterns of identification for special education services across three cohorts of students in kindergarten through third grade before and after implementation of a schoolwide, three-tier reading prevention model in one large school district are reported. The first cohort of students represents a historical control group that did not participate in…

  17. Reading-Related Behavior in an Open Classroom: Effects of Novelty and Modeling on Preschoolers

    ERIC Educational Resources Information Center

    Haskett, G. J.; Lenfestey, W.

    1975-01-01

    Preschool reading behavior did not arise necessarily or spontaneously in an open classroom where a set of books was continually available. Because the open classroom acquires new properties and meanings when contrasted with the traditional school, complex factors influencing behavior, such as novelty and modeling, must be examined. (BJG)

  18. 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…

  19. 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…

  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. 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…

  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. Effects of Tape-Recorded Aural Models on Sight-Reading and Performance Skills.

    ERIC Educational Resources Information Center

    Anderson, James N.

    1981-01-01

    Investigated the effect of using tape-recorded aural models for home practice on selected sight-reading and performance skills of sixth-grade clarinet students. The tape recordings had no observed effects on the selected music skills, nor did the students using them complete more music exercises, as had been hypothesized. (Author/SJL)

  4. 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

  5. The componential model of reading: predicting first grade reading performance of culturally diverse students from ecological, psychological, and cognitive factors assessed at kindergarten entry.

    PubMed

    Ortiz, Miriam; Folsom, Jessica S; Al Otaiba, Stephanie; Greulich, Luana; Thomas-Tate, Shurita; Connor, Carol M

    2012-01-01

    This study, framed by the component model of reading (CMR), examined the relative importance of kindergarten-entry predictors of first grade reading performance. Specifically, elements within the ecological domain included dialect, maternal education, amount of preschool, and home literacy; elements within the psychological domain included teacher-reported academic competence, social skills, and behavior; and elements within the cognitive domain included initial vocabulary, phonological, and morpho-syntactic skills, and alphabetic and word recognition skills. Data were obtained for 224 culturally diverse kindergarteners (58% Black, 34% White, and 8% Hispanic or other; 58% received free or reduced-price lunch) from a larger study conducted in seven predominantly high poverty schools (n = 20 classrooms) in a midsized city school district in northern Florida. Results from a hierarchical multiple regression (with variables in the ecological domain entered first, followed by the psychological and cognitive domains) revealed a model that explained roughly 56% of the variance in first grade reading achievement, using fall-of-kindergarten predictors. Letter-word reading and morpho-syntactic skill were the strongest significant predictors. The findings largely support the CMR model as a means to understand individual differences in reading acquisition and, in turn, to support data-based instructional decisions for a wider range of children. PMID:22227395

  6. 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…

  7. 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…

  8. 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…

  9. 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

  10. 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. PMID:24324240

  11. MODELING COLLISIONAL CASCADES IN DEBRIS DISKS: STEEP DUST-SIZE DISTRIBUTIONS

    SciTech Connect

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

    2012-07-20

    We explore the evolution of the mass distribution of dust in collision-dominated debris disks, using the collisional code introduced in our previous paper. We analyze the equilibrium distribution and its dependence on model parameters by evolving over 100 models to 10 Gyr. With our numerical models, we confirm that systems reach collisional equilibrium with a mass distribution that is steeper than the traditional solution by Dohnanyi. Our model yields a quasi-steady-state slope of n(m) {approx} m{sup -1.88} [n(a) {approx} a{sup -3.65}] as a robust solution for a wide range of possible model parameters. We also show that a simple power-law function can be an appropriate approximation for the mass distribution of particles in certain regimes. The steeper solution has observable effects in the submillimeter and millimeter wavelength regimes of the electromagnetic spectrum. We assemble data for nine debris disks that have been observed at these wavelengths and, using a simplified absorption efficiency model, show that the predicted slope of the particle-mass distribution generates spectral energy distributions that are in agreement with the observed ones.

  12. 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

  13. End-to-end flood risk assessment: A coupled model cascade with uncertainty estimation

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary K.; Brasington, James

    2008-03-01

    This paper presents the case for an `End-to-End' flood inundation modeling strategy: the creation of a coupled system of models to allow continuous simulation methodology to be used to predict the magnitude and simulate the effects of high return period flood events. The framework brings together the best in current thinking on reduced complexity modeling to formulate an efficient, process-based methodology which meets the needs of today's flood mitigation strategies. The model chain is subject to stochasticity and parameter uncertainty, and integral methods to allow the propagation and quantification of uncertainty are essential in order to produce robust estimates of flood risk. Results from an experimental application are considered in terms of their implications for successful floodplain management, and compared against the deterministic methodology more commonly in use for flood risk assessment applications. The provenance of predictive uncertainty is also considered in order to identify those areas where future effort in terms of data collection or model refinement might best be directed in order to narrow prediction bounds and produce a more precise forecast.

  14. 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

  15. Modelling normal and impaired letter recognition: Implications for understanding pure alexic reading

    PubMed Central

    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 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. PMID:22841988

  16. 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. PMID:22841988

  17. A field- and modeling- based study of the denudation and topographic evolution of the Washington Cascades

    NASA Astrophysics Data System (ADS)

    Masteller, C.; Finnegan, N. J.; Miller, I. M.; Warrick, J. A.

    2011-12-01

    Kelp forests support diverse assemblages of organisms and grow along many rocky coastlines. Since the flow of water through kelp forests controls the transport and fate of nutrients in near shore environments, the hydrodynamics of kelp forests are well studied. In addition, a number of studies have observed transport of large grains attached to seaweed and/or kelp holdfasts. Such observations suggest that the biology colonizing the littoral zone may fundamentally influence coarse sediment transport processes. In this contribution, we set out to quantify the effect of kelp on near shore, current driven coarse sediment transport. By exploiting an existing model for kelp hydrodynamics, we build a physical model for incipient motion of a coarse grain coupled to a kelp frond under a unidirectional current. This model accounts for the additional buoyant, drag, and tensional forces transmitted from a kelp frond to the attached sediment. Application of the model demonstrates that the large surface area of kelp results in an increase in drag force, while the pull of the buoyant kelp frond reduces friction on the grain. Further, as the fluid flows over the kelp frond, it will 'go with the flow', stretching, and applying a tensional stress. Together, these effects significantly reduce the threshold stress for the initiation of motion. Thus kelp-assisted transport can occur at reduced fluid velocities where coarse sediment transport would otherwise be impossible. In addition, the results of this study provide an example of a system where biology must be explicitly accounted for in order to model coarse sediment transport accurately.

  18. Accuracy requirements to test the applicability of the random cascade model to supersonic turbulence

    NASA Astrophysics Data System (ADS)

    Folini, Doris; Walder, Rolf

    2016-03-01

    A model, which is widely used for inertial rang statistics of supersonic turbulence in the context of molecular clouds and star formation, expresses (measurable) relative scaling exponents Zp of two-point velocity statistics as a function of two parameters, β and Δ. The model relates them to the dimension D of the most dissipative structures, D = 3 - Δ/(1 - β). While this description has proved most successful for incompressible turbulence (β = Δ = 2/3, and D = 1), its applicability in the highly compressible regime remains debated. For this regime, theoretical arguments suggest D = 2 and Δ = 2/3, or Δ = 1. Best estimates based on 3D periodic box simulations of supersonic isothermal turbulence yield Δ = 0.71 and D = 1.9, with uncertainty ranges of Δ ∈ [0.67,0.78] and D ∈ [2.04,1.60]. With these 5-10% uncertainty ranges just marginally including the theoretical values of Δ = 2/3 and D = 2, doubts remain whether the model indeed applies and, if it applies, for what values of β and Δ. We use a Monte Carlo approach to mimic actual simulation data and examine what factors are most relevant for the fit quality. We estimate that 0.1% (0.05%) accurate Zp, with p = 1,...,5, should allow for 2% (1%) accurate estimates of β and Δ in the highly compressible regime, but not in the mildly compressible regime. We argue that simulation-based Zp with such accuracy are within reach of today's computer resources. If this kind of data does not allow for the expected high quality fit of β and Δ, then this may indicate the inapplicability of the model for the simulation data. In fact, other models than the one we examine here have been suggested.

  19. An efficient and scalable graph modeling approach for capturing information at different levels in next generation sequencing reads

    PubMed Central

    2013-01-01

    Background Next generation sequencing technologies have greatly advanced many research areas of the biomedical sciences through their capability to generate massive amounts of genetic information at unprecedented rates. The advent of next generation sequencing has led to the development of numerous computational tools to analyze and assemble the millions to billions of short sequencing reads produced by these technologies. While these tools filled an important gap, current approaches for storing, processing, and analyzing short read datasets generally have remained simple and lack the complexity needed to efficiently model the produced reads and assemble them correctly. Results Previously, we presented an overlap graph coarsening scheme for modeling read overlap relationships on multiple levels. Most current read assembly and analysis approaches use a single graph or set of clusters to represent the relationships among a read dataset. Instead, we use a series of graphs to represent the reads and their overlap relationships across a spectrum of information granularity. At each information level our algorithm is capable of generating clusters of reads from the reduced graph, forming an integrated graph modeling and clustering approach for read analysis and assembly. Previously we applied our algorithm to simulated and real 454 datasets to assess its ability to efficiently model and cluster next generation sequencing data. In this paper we extend our algorithm to large simulated and real Illumina datasets to demonstrate that our algorithm is practical for both sequencing technologies. Conclusions Our overlap graph theoretic algorithm is able to model next generation sequencing reads at various levels of granularity through the process of graph coarsening. Additionally, our model allows for efficient representation of the read overlap relationships, is scalable for large datasets, and is practical for both Illumina and 454 sequencing technologies. PMID:24564333

  20. 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.

  1. 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. PMID:24580692

  2. How Do Young Deaf Children Learn to Read? A Proposed Model of Deaf Children's Emergent Reading Behaviors. Technical Report No. 329.

    ERIC Educational Resources Information Center

    Andrews, Jean F.; Mason, Jana M.

    Evidence from a nine-month longitudinal study of deaf children's early attempts at learning to read provides the construct for an instructional model that stresses that even though the children may have, at the least, a meager expressive sign language vocabulary, they can be lead successfully through the holophrastic or one-word stage of reading…

  3. 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

  4. 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.

  5. 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

  6. Modelling Reading Times in Different Reading Tasks with a Simulation Model of Comprehension. Technical Report, May 1, 1978 through March 30, 1979.

    ERIC Educational Resources Information Center

    Kieras, David E.

    Reading times can be a valuable source of data on comprehension processes, especially in the case of recording reading times on individual sentences in a passage. To overcome the methodological problems encountered in other research efforts concerning reading times, a multiple regression method was used to compare an ordinary language processing…

  7. 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

  8. Modeling the Relations Among Morphological Awareness Dimensions, Vocabulary Knowledge, and Reading Comprehension in Adult Basic Education Students.

    PubMed

    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

  9. 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.

  10. 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…

  11. The Effects of Video Self-Modeling on the Decoding Skills of Children at Risk for Reading Disabilities

    ERIC Educational Resources Information Center

    Ayala, Sandra M.

    2010-01-01

    Ten first grade students, participating in a Tier II response to intervention (RTI) reading program received an intervention of video self modeling to improve decoding skills and sight word recognition. The students were video recorded blending and segmenting decodable words, and reading sight words taken directly from their curriculum…

  12. Cascade defense via routing in complex networks

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Lan; Du, Wen-Bo; Hong, Chen

    2015-05-01

    As the cascading failures in networked traffic systems are becoming more and more serious, research on cascade defense in complex networks has become a hotspot in recent years. In this paper, we propose a traffic-based cascading failure model, in which each packet in the network has its own source and destination. When cascade is triggered, packets will be redistributed according to a given routing strategy. Here, a global hybrid (GH) routing strategy, which uses the dynamic information of the queue length and the static information of nodes' degree, is proposed to defense the network cascade. Comparing GH strategy with the shortest path (SP) routing, efficient routing (ER) and global dynamic (GD) routing strategies, we found that GH strategy is more effective than other routing strategies in improving the network robustness against cascading failures. Our work provides insight into the robustness of networked traffic systems.

  13. Coarse Grained Approach to First Principles Modeling of Radiation Cascade in Large Fe Supercells

    NASA Astrophysics Data System (ADS)

    Odbadrakh, Kh; Nicholson, D. M.; Rusanu, A.; Samolyuk, G. D.; Stoller, R. E.; Zhang, X.-G.; Stocks, G. M.

    2012-12-01

    Classical Molecular Dynamics (MD) simulations characterizing dislocations and radiation damage typically treat 105-107 atoms. First principles techniques employed to understand systems at an atomistic level are not practical for such large systems consisting of millions of atoms. We present an efficient coarse grained (CG) approach to calculate local electronic and magnetic properties of large MD-generated structures from the first principles. Local atomic magnetic moments in crystalline Fe are perturbed by the presence of radiation generated vacancies and interstitials. The effects are most pronounced near the defect cores and decay slowly as the strain field of the defects decrease with distance. We develop the CG 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. The calculations result in local moments near the defect centers with first-principles accuracy, while capturing coarse-grained details of local moments at greater length scales. This CG approach makes these large scale structures amenable to first principles study.

  14. 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.

  15. 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…

  16. Emerging Theoretical Models of Reading through Authentic Assessments among Preservice Teachers: Two Case Studies

    ERIC Educational Resources Information Center

    Oboler, Eileen S.; Gupta, Abha

    2010-01-01

    This two-part study examines the emerging understanding of the reading process among preservice teachers (PTs), enrolled in a teacher preparation course on diagnostic reading. The study focuses on the use of reading assessment tools to understand the process of reading, while using reading inventories for diagnostic as well as pedagogical…

  17. 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)

  18. Abrogation of STAT3 signaling cascade by zerumbone inhibits proliferation and induces apoptosis in renal cell carcinoma xenograft mouse model.

    PubMed

    Shanmugam, Muthu K; Rajendran, Peramaiyan; Li, Feng; Kim, Chulwon; Sikka, Sakshi; Siveen, Kodappully Sivaraman; Kumar, Alan Prem; Ahn, Kwang Seok; Sethi, Gautam

    2015-10-01

    Persistent activation of signal transducer and activator of transcription 3 (STAT3) is one of the characteristic features of renal cell carcinoma (RCC) and often linked to its deregulated proliferation, survival, and angiogenesis. In the present report, we investigated whether zerumbone, a sesquiterpene, exerts its anticancer effect through modulation of STAT3 activation pathway. The pharmacological effect of zerumbone on STAT3 activation, associated protein kinases and phosphatase, and apoptosis was investigated using both RCC cell lines and xenograft mouse model. We observed that zerumbone suppressed STAT3 activation in a dose- and time-dependent manner in RCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Pervanadate treatment reversed zerumbone-induced downregulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that zerumbone induced the expression of tyrosine phosphatase SHP-1 that correlated with its ability to inhibit STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of zerumbone to inhibit STAT3 activation. The inhibition of STAT3 activation by zerumbone also caused the suppression of the gene products involved in proliferation, survival, and angiogenesis. Finally, when administered i.p., zerumbone inhibited STAT3 activation in tumor tissues and the growth of human RCC xenograft tumors in athymic nu/nu mice without any side effects. Overall, our results suggest for the first time that zerumbone is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of RCC and other solid tumors. PMID:24797723

  19. List context effects in languages with opaque and transparent orthographies: a challenge for models of reading

    PubMed Central

    Traficante, Daniela; Burani, Cristina

    2014-01-01

    This paper offers a review of data which show that reading is a flexible and dynamic process and that readers can exert strategic control over it. Two main hypotheses on the control of reading processes have been suggested: the route de-emphasis hypothesis and the time-criterion hypothesis. According to the former, the presence of irregular words in the list might lead to an attenuation of the non-lexical process, while the presence of non-words could trigger a de-emphasis of the lexical route. An alternative account is proposed by the time-criterion hypothesis whereby the reader sets a flexible deadline to initiate the response. According to the latter view, it is the average pronunciation difficulty of the items in the block that modulates the time-criterion for response. However, it is worth noting that the list composition has been shown to exert different effects in transparent compared to opaque orthographies, as the consistency of spelling-sound correspondences can influence the processing costs of the non-lexical pathway. In transparent orthographies, the non-lexical route is not resource demanding and can successfully contribute to the pronunciation of regular words, thus its de-emphasis could not be as useful/necessary as in opaque orthographies. The complex patterns of results from the literature on list context effects are a challenge for computational models of reading which face the problem of simulating strategic control over reading processes. Different proposals suggest a modification of parameter setting in the non-lexical route or the implementation of a new module aimed at focusing attention on the output of the more convenient pathway. Simulation data and an assessment of the models’ fit to the behavioral results are presented and discussed to shed light on the role of the cognitive system when reading aloud. PMID:25309485

  20. Developmental cascade models of a parenting-focused program for divorced families on mental health problems and substance use in emerging adulthood.

    PubMed

    Wolchik, Sharlene A; Tein, Jenn-Yun; Sandler, Irwin N; Kim, Han-Joe

    2016-08-01

    A developmental cascade model from functioning in adolescence to emerging adulthood was tested using data from a 15-year longitudinal follow-up of 240 emerging adults whose families participated in a randomized, experimental trial of a preventive program for divorced families. Families participated in the program or literature control condition when the offspring were ages 9-12. Short-term follow-ups were conducted 3 months and 6 months following completion of the program when the offspring were in late childhood/early adolescence. Long-term follow-ups were conducted 6 years and 15 years after program completion when the offspring were in middle to late adolescence and emerging adulthood, respectively. It was hypothesized that the impact of the program on mental health and substance use outcomes in emerging adulthood would be explained by developmental cascade effects of program effects in adolescence. The results provided support for a cascade effects model. Specifically, academic competence in adolescence had cross-domain effects on internalizing problems and externalizing problems in emerging adulthood. In addition, adaptive coping in adolescence was significantly, negatively related to binge drinking. It was unexpected that internalizing symptoms in adolescence were significantly negatively related to marijuana use and alcohol use. Gender differences occurred in the links between mental health problems and substance use in adolescence and mental health problems and substance use in emerging adulthood. PMID:27427811

  1. 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

  2. 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. PMID:26072764

  3. Teaching Reading

    ERIC Educational Resources Information Center

    Day, Richard R.

    2013-01-01

    "Teaching Reading" uncovers the interactive processes that happen when people learn to read and translates them into a comprehensive easy-to-follow guide on how to teach reading. Richard Day's revelations on the nature of reading, reading strategies, reading fluency, reading comprehension, and reading objectives make fascinating…

  4. 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.

  5. 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

  6. Rescuing Ecosystems from Extinction Cascades

    NASA Astrophysics Data System (ADS)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  7. 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.

  8. Proton Pump Inhibitors and the Prescribing Cascade.

    PubMed

    Rababa, Mohammad; Al-Ghassani, Amal Ali; Kovach, Christine R; Dyer, Elaine M

    2016-04-01

    HOW TO OBTAIN CONTACT HOURS BY READING THIS ARTICLE Instructions 1.3 contact hours will be awarded by Villanova University College of Nursing upon successful completion of this activity. A contact hour is a unit of measurement that denotes 60 minutes of an organized learning activity. This is a learner-based activity. Villanova University College of Nursing does not require submission of your answers to the quiz. A contact hour certificate will be awarded once you register, pay the registration fee, and complete the evaluation form online at http://goo.gl/gMfXaf. To obtain contact hours you must: 1. Read the article, "Proton Pump Inhibitors and the Prescribing Cascade" found on pages 23-31, carefully noting any tables and other illustrative materials that are included to enhance your knowledge and understanding of the content. Be sure to keep track of the amount of time (number of minutes) you spend reading the article and completing the quiz. 2. Read and answer each question on the quiz. After completing all of the questions, compare your answers to those provided within this issue. If you have incorrect answers, return to the article for further study. 3. Go to the Villanova website listed above to register for contact hour credit. You will be asked to provide your name; contact information; and a VISA, MasterCard, or Discover card number for payment of the $20.00 fee. Once you complete the online evaluation, a certificate will be automatically generated. This activity is valid for continuing education credit until March 31, 2019. CONTACT HOURS This activity is co-provided by Villanova University College of Nursing and SLACK Incorporated. Villanova University College of Nursing is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's Commission on Accreditation. ACTIVITY OBJECTIVES 1. Describe the prescribing cascade of proton pump inhibitors (PPI) in nursing home residents. 2. Identify the statistically

  9. Reading Disability: A Model for the Genetic Analysis of Complex Behavioral Disorders.

    ERIC Educational Resources Information Center

    LaBuda, Michele C.; And Others

    1990-01-01

    Reviews family, linkage, and twin studies of reading disability. Reports on application of behavioral genetic methods to reading performance data from 96 identical twin pairs and 72 fraternal twin pairs in which at least one twin was reading disabled. Found approximately one-half of the reading deficit observed in the probands may have been…

  10. 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…

  11. 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

  12. Modeling the Vakhsh Cascade in the Amu Darya River Basin - Implementing Future Storage Facilities in a Hydrological Model for Impact Assessment

    NASA Astrophysics Data System (ADS)

    Steiner, J. F.; Siegfried, T.; Yakovlev, A.

    2014-12-01

    In the Amu Darya River Basin in Central Asia, the Vakhsh catchment in Tajikistan is a major source of hydropower energy for the country. With a number of large dams already constructed, upstream Tajikistan is interested in the construction of one more large dam and a number of smaller storage facilities with the prospect of supplying its neighboring states with hydropower through a newly planned power grid. The impact of new storage facilities along the river is difficult to estimate and causes considerable concern and consternation among the downstream users. Today, it is one of the vexing poster child studies in international water conflict that awaits resolution. With a lack of meteorological data and a complex topography that makes application of remote sensed data difficult it is a challenge to model runoff correctly. Large parts of the catchment is glacierized and ranges from just 500 m asl to peaks above 7000 m asl. Based on in-situ time series for temperature and precipitation we find local correction factors for remote sensed products. Using this data we employ a model based on the Budyko framework with an extension for snow and ice in the higher altitude bands. The model furthermore accounts for groundwater and soil storage. Runoff data from a number of stations are used for the calibration of the model parameters. With an accurate representation of the existing and planned reservoirs in the Vakhsh cascade we study the potential impacts from the construction of the new large reservoir in the river. Impacts are measured in terms of a) the timing and availability of new hydropower energy, also in light of its potential for export to South Asia, b) shifting challenges with regard to river sediment loads and siltation of reservoirs and c) impacts on downstream runoff and the timely availability of irrigation water there. With our coupled hydro-climatological approach, the challenges of optimal cascade management can be addressed so as to minimize detrimental

  13. Modeling individual differences in text reading fluency: a different pattern of predictors for typically developing and dyslexic readers

    PubMed Central

    Zoccolotti, Pierluigi; De Luca, Maria; Marinelli, Chiara V.; Spinelli, Donatella

    2014-01-01

    This study was aimed at predicting individual differences in text reading fluency. The basic proposal included two factors, i.e., the ability to decode letter strings (measured by discrete pseudo-word reading) and integration of the various sub-components involved in reading (measured by Rapid Automatized Naming, RAN). Subsequently, a third factor was added to the model, i.e., naming of discrete digits. In order to use homogeneous measures, all contributing variables considered the entire processing of the item, including pronunciation time. The model, which was based on commonality analysis, was applied to data from a group of 43 typically developing readers (11- to 13-year-olds) and a group of 25 chronologically matched dyslexic children. In typically developing readers, both orthographic decoding and integration of reading sub-components contributed significantly to the overall prediction of text reading fluency. The model prediction was higher (from ca. 37 to 52% of the explained variance) when we included the naming of discrete digits variable, which had a suppressive effect on pseudo-word reading. In the dyslexic readers, the variance explained by the two-factor model was high (69%) and did not change when the third factor was added. The lack of a suppression effect was likely due to the prominent individual differences in poor orthographic decoding of the dyslexic children. Analyses on data from both groups of children were replicated by using patches of colors as stimuli (both in the RAN task and in the discrete naming task) obtaining similar results. We conclude that it is possible to predict much of the variance in text-reading fluency using basic processes, such as orthographic decoding and integration of reading sub-components, even without taking into consideration higher-order linguistic factors such as lexical, semantic and contextual abilities. The approach validity of using proximal vs. distal causes to predict reading fluency is discussed. PMID

  14. Cascading failures and the emergence of cooperation in evolutionary-game based models of social and economical networks.

    PubMed

    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. PMID:21974647

  15. 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.

  16. 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.

  17. 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

  18. 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. PMID:24815949

  19. 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

  20. 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. PMID:26913014

  1. 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.

  2. 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. PMID:25095787

  3. Critical transitions in colliding cascades

    PubMed

    Gabrielov; Keilis-Borok; Zaliapin; Newman

    2000-07-01

    We consider here the interaction of direct and inverse cascades in a hierarchical nonlinear system that is continuously loaded by external forces. The load is applied to the largest element and is transferred down the hierarchy to consecutively smaller elements, thereby forming a direct cascade. The elements of the system fail (i. e., break down) under the load. The smallest elements fail first. The failures gradually expand up the hierarchy to the larger elements, thus forming an inverse cascade. Eventually the failures heal, ensuring that the system will function indefinitely. The direct and inverse cascades collide and interact. Loading triggers the failures, while failures release and redistribute the load. Notwithstanding its relative simplicity, this model reproduces the major dynamical features observed in seismicity, including the seismic cycle, intermittence of seismic regime, power-law energy distribution, clustering in space and time, long-range correlations, and a set of seismicity patterns premonitory to a strong earthquake. In this context, the hierarchical structure of the model crudely imitates a system of tectonic blocks spread by a network of faults (note that the behavior of such a network is different from that of a single fault). Loading mimics the impact of tectonic forces, and failures simulate earthquakes. The model exhibits three basic types of premonitory pattern reflecting seismic activity, clustering of earthquakes in space and time, and the range of correlation between the earthquakes. The colliding-cascade model seemingly exhibits regularities that are common in a wide class of complex hierarchical systems, not necessarily Earth specific. PMID:11088457

  4. Modeling a Cascade of Effects: The Role of Speed and Executive Functioning in Preterm/Full-Term Differences in Academic Achievement

    ERIC Educational Resources Information Center

    Rose, Susan A.; Feldman, Judith F.; Jankowski, Jeffery J.

    2011-01-01

    This study identified deficits in executive functioning in pre-adolescent preterms and modeled their role, along with processing speed, in explaining preterm/full-term differences in reading and mathematics. Preterms (less than 1750 g) showed deficits at 11 years on a battery of tasks tapping the three basic executive functions identified by…

  5. Motivating Reading Comprehension: Concept-Oriented Reading Instruction

    ERIC Educational Resources Information Center

    Guthrie, John T., Ed.; Wigfield, Allan, Ed.; Perencevich, Kathleen C., Ed.

    2004-01-01

    Concept Oriented Reading Instruction (CORI) is a unique, classroom-tested model of reading instruction that breaks new ground by explicitly showing how content knowledge, reading strategies, and motivational support all merge in successful reading instruction. A theoretical perspective (engagement in reading) frames the book and provides a…

  6. A multiobjective short-term optimal operation model for a cascade system of reservoirs considering the impact on long-term energy production

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Zhong, Ping-An; Stanko, Zachary; Zhao, Yunfa; Yeh, William W.-G.

    2015-05-01

    This paper examines the impact of short-term operation on long-term energy production. We propose a multiobjective optimization model for the short-term, daily operation of a system of cascade reservoirs. The two objectives considered in the daily model are: (1) minimizing the total amount of water released and (2) maximizing the stored energy in the system. Optimizing short-term operation without considering its impact on long-term energy production does not guarantee maximum energy production in the system. Therefore, a major goal of this paper is to identify desirable short-term operation strategies that, at the same time, optimize long-term energy production. First, we solve the daily model for 1 month (30 days) using a nondominated genetic algorithm (NSGAII). We then use the nondominated solutions obtained by NSGAII to assess the impact on long-term energy production using a monthly model. We use historical monthly inflows to characterize the inflow variability. We apply the proposed methodology to the Qingjiang cascade system of reservoirs in China. The results show: (1) in average hydrology scenarios, the solution maximizing stored energy produces the most overall long-term energy production; (2) in moderately wet hydrology scenarios, the solution minimizing water released outperforms the maximizing stored energy solution; and (3) when extremely wet hydrology scenarios are expected, a compromise solution is the best strategy.

  7. 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)

  8. 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.

  9. 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.

  10. Thermally cascaded thermoelectric generator

    NASA Technical Reports Server (NTRS)

    Flaherty, R.

    1970-01-01

    High efficiency thermoelectric generator utilizes a high-temperature thermoelectric material in thermal series with a low-temperature material. A thermally cascaded generator increases system efficiency.

  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 cascaded model of spectral distortions due to spectral response effects and pulse pileup effects in a photon-counting x-ray detector for CT

    SciTech Connect

    Cammin, Jochen E-mail: ktaguchi@jhmi.edu; Taguchi, Katsuyuki E-mail: ktaguchi@jhmi.edu; Xu, Jennifer; Barber, William C.; Iwanczyk, Jan S.; Hartsough, Neal E.

    2014-04-15

    Purpose: Energy discriminating, photon-counting detectors (PCDs) are an emerging technology for computed tomography (CT) with various potential benefits for clinical CT. The photon energies measured by PCDs can be distorted due to the interactions of a photon with the detector and the interaction of multiple coincident photons. These effects result in distorted recorded x-ray spectra which may lead to artifacts in reconstructed CT images and inaccuracies in tissue identification. Model-based compensation techniques have the potential to account for the distortion effects. This approach requires only a small number of parameters and is applicable to a wide range of spectra and count rates, but it needs an accurate model of the spectral distortions occurring in PCDs. The purpose of this study was to develop a model of those spectral distortions and to evaluate the model using a PCD (model DXMCT-1; DxRay, Inc., Northridge, CA) and various x-ray spectra in a wide range of count rates. Methods: The authors hypothesize that the complex phenomena of spectral distortions can be modeled by: (1) separating them into count-rate independent factors that we call the spectral response effects (SRE), and count-rate dependent factors that we call the pulse pileup effects (PPE), (2) developing separate models for SRE and PPE, and (3) cascading the SRE and PPE models into a combined SRE+PPE model that describes PCD distortions at both low and high count rates. The SRE model describes the probability distribution of the recorded spectrum, with a photo peak and a continuum tail, given the incident photon energy. Model parameters were obtained from calibration measurements with three radioisotopes and then interpolated linearly for other energies. The PPE model used was developed in the authors’ previous work [K. Taguchi et al., “Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects,” Med. Phys. 38(2), 1089–1102 (2011

  13. 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.

  14. 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…

  15. 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…

  16. 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.

  17. Internuclear cascade-evaporation model for LET spectra of 200 MeV protons used for parts testing

    SciTech Connect

    O`Neill, P.M.; Badhwar, G.D.; Culpepper, W.X.

    1998-12-01

    The Linear Energy Transfer (LET) spectrum produced in microelectronic components during testing with 200 MeV protons is calculated with an internuclear cascade-evaporation code. This spectrum is compared to the natural space heavy ion environment for various earth orbits. This comparison is used to evaluate the results of proton testing in terms of determining a firm upper bound to the on-orbit heavy ion upset rate and the risk of on-orbit heavy ion failures that would not be detected with protons.

  18. 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., Jr.; 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

  19. 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.…

  20. 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…

  1. PANEL CODE FOR PLANAR CASCADES

    NASA Technical Reports Server (NTRS)

    Mcfarland, E. R.

    1994-01-01

    The Panel Code for Planar Cascades was developed as an aid for the designer of turbomachinery blade rows. The effective design of turbomachinery blade rows relies on the use of computer codes to model the flow on blade-to-blade surfaces. Most of the currently used codes model the flow as inviscid, irrotational, and compressible with solutions being obtained by finite difference or finite element numerical techniques. While these codes can yield very accurate solutions, they usually require an experienced user to manipulate input data and control parameters. Also, they often limit a designer in the types of blade geometries, cascade configurations, and flow conditions that can be considered. The Panel Code for Planar Cascades accelerates the design process and gives the designer more freedom in developing blade shapes by offering a simple blade-to-blade flow code. Panel, or integral equation, solution techniques have been used for several years by external aerodynamicists who have developed and refined them into a primary design tool of the aircraft industry. The Panel Code for Planar Cascades adapts these same techniques to provide a versatile, stable, and efficient calculation scheme for internal flow. The code calculates the compressible, inviscid, irrotational flow through a planar cascade of arbitrary blade shapes. Since the panel solution technique is for incompressible flow, a compressibility correction is introduced to account for compressible flow effects. The analysis is limited to flow conditions in the subsonic and shock-free transonic range. Input to the code consists of inlet flow conditions, blade geometry data, and simple control parameters. Output includes flow parameters at selected control points. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 590K of 8 bit bytes. This program was developed in 1982.

  2. 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…

  3. 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.

  4. 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

  5. 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. PMID:23300760

  6. 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.

  7. 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…

  8. 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…

  9. 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…

  10. 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…

  11. 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.

  12. 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…

  13. 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…

  14. Do Current Connectionist Learning Models Account for Reading Development in Different Languages?

    ERIC Educational Resources Information Center

    Hutzler, Florian; Ziegler, Johannes C.; Perry, Conrad; Wimmer, Heinz; Zorzi, Marco

    2004-01-01

    Learning to read a relatively irregular orthography, such as English, is harder and takes longer than learning to read a relatively regular orthography, such as German. At the end of grade 1, the difference in reading performance on a simple set of words and nonwords is quite dramatic. Whereas children using regular orthographies are already close…

  15. 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…

  16. The Content-based Reading Approaches (COBRA) Model in the ELL and LD Classroom

    ERIC Educational Resources Information Center

    Lee, Pei-Yi

    2010-01-01

    The Content-based Reading Approaches (COBRA) framework, constructed by Heerman (2002), was made up of the instructional goals designed for reading-learning integrations in subject matter classrooms. ELL and LD students often fail to have sufficient reading skills to succeed within their different academic subjects, consequently it is important for…

  17. 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. PMID:21044539

  18. 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. PMID:20577589

  19. Orthographic influences on division of labor in learning to read Chinese and English: Insights from computational modeling

    PubMed Central

    Yang, Jianfeng; Shu, Hua; McCandliss, Bruce D.; Zevin, Jason D.

    2013-01-01

    Learning to read any language requires learning to map among print, sound and meaning. Writing systems differ in a number of factors that influence both the ease and rate with which reading skill can be acquired, as well as the eventual division of labor between phonological and semantic processes. Further, developmental reading disability manifests differently across writing systems, and may be related to different deficits in constitutive processes. Here we simulate some aspects of reading acquisition in Chinese and English using the same model architecture for both writing systems. The contribution of semantic and phonological processing to literacy acquisition in the two languages is simulated, including specific effects of phonological and semantic deficits. Further, we demonstrate that similar patterns of performance are observed when the same model is trained on both Chinese and English as an "early bilingual." The results are consistent with the view that reading skill is acquired by the application of statistical learning rules to mappings among print, sound and meaning, and that differences in the typical and disordered acquisition of reading skill between writing systems are driven by differences in the statistical patterns of the writing systems themselves, rather than differences in cognitive architecture of the learner. PMID:24587693

  20. Orthographic influences on division of labor in learning to read Chinese and English: Insights from computational modeling.

    PubMed

    Yang, Jianfeng; Shu, Hua; McCandliss, Bruce D; Zevin, Jason D

    2013-04-01

    Learning to read any language requires learning to map among print, sound and meaning. Writing systems differ in a number of factors that influence both the ease and rate with which reading skill can be acquired, as well as the eventual division of labor between phonological and semantic processes. Further, developmental reading disability manifests differently across writing systems, and may be related to different deficits in constitutive processes. Here we simulate some aspects of reading acquisition in Chinese and English using the same model architecture for both writing systems. The contribution of semantic and phonological processing to literacy acquisition in the two languages is simulated, including specific effects of phonological and semantic deficits. Further, we demonstrate that similar patterns of performance are observed when the same model is trained on both Chinese and English as an "early bilingual." The results are consistent with the view that reading skill is acquired by the application of statistical learning rules to mappings among print, sound and meaning, and that differences in the typical and disordered acquisition of reading skill between writing systems are driven by differences in the statistical patterns of the writing systems themselves, rather than differences in cognitive architecture of the learner. PMID:24587693

  1. Extension of the Liège intranuclear cascade model at incident energies between 2 and 12 GeV. Aspects of pion production

    NASA Astrophysics Data System (ADS)

    Pedoux, Sophie; Cugnon, Joseph

    2011-09-01

    The validity of the standard version of the Liège Intra-Nuclear Cascade (INCL4) model, which has been shown to be quite successful for the description of spallation reactions, is limited to an upper incident energy of ˜2 GeV, because inelastic elementary processes are restricted to the excitation and de-excitation of the Delta resonance. In this paper, the INCL4 model is extended to higher incident energy by including other inelastic elementary collisions. However, excitation of heavier baryonic resonances is replaced by direct multipion production in elementary nucleon-nucleon and pion-nucleon collisions. The predictions of the modified model for production of charged pions by proton and pion beams off nuclei are compared with experimental data of the HARP Collaboration for beam energies between 2 and 12 GeV. The apparent duality between the approach based on excitation of numerous baryonic resonances and our approach is briefly discussed.

  2. Long-read, whole-genome shotgun sequence data for five model organisms

    PubMed Central

    Kim, Kristi E; Peluso, Paul; Babayan, Primo; Yeadon, P. Jane; Yu, Charles; Fisher, William W; Chin, Chen-Shan; Rapicavoli, Nicole A; Rank, David R; Li, Joachim; Catcheside, David E. A; Celniker, Susan E; Phillippy, Adam M; Bergman, Casey M; Landolin, Jane M

    2014-01-01

    Single molecule, real-time (SMRT) sequencing from Pacific Biosciences is increasingly used in many areas of biological research including de novo genome assembly, structural-variant identification, haplotype phasing, mRNA isoform discovery, and base-modification analyses. High-quality, public datasets of SMRT sequences can spur development of analytic tools that can accommodate unique characteristics of SMRT data (long read lengths, lack of GC or amplification bias, and a random error profile leading to high consensus accuracy). In this paper, we describe eight high-coverage SMRT sequence datasets from five organisms (Escherichia coli, Saccharomyces cerevisiae, Neurospora crassa, Arabidopsis thaliana, and Drosophila melanogaster) that have been publicly released to the general scientific community (NCBI Sequence Read Archive ID SRP040522). Data were generated using two sequencing chemistries (P4C2 and P5C3) on the PacBio RS II instrument. The datasets reported here can be used without restriction by the research community to generate whole-genome assemblies, test new algorithms, investigate genome structure and evolution, and identify base modifications in some of the most widely-studied model systems in biological research. PMID:25977796

  3. REMEDIATING READING DIFFICULTIES IN A RESPONSE TO INTERVENTION MODEL WITH SECONDARY STUDENTS.

    PubMed

    Pyle, Nicole; Vaughn, Sharon

    2012-03-01

    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. 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…

  5. Empirical Differences in Omission Tendency and Reading Ability in PISA: An Application of Tree-Based Item Response Models

    ERIC Educational Resources Information Center

    Okumura, Taichi

    2014-01-01

    This study examined the empirical differences between the tendency to omit items and reading ability by applying tree-based item response (IRTree) models to the Japanese data of the Programme for International Student Assessment (PISA) held in 2009. For this purpose, existing IRTree models were expanded to contain predictors and to handle…

  6. 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)…

  7. Beyond single syllables: large-scale modeling of reading aloud with the Connectionist Dual Process (CDP++) model.

    PubMed

    Perry, Conrad; Ziegler, Johannes C; Zorzi, Marco

    2010-09-01

    Most words in English have more than one syllable, yet the most influential computational models of reading aloud are restricted to processing monosyllabic words. Here, we present CDP++, a new version of the Connectionist Dual Process model (Perry, Ziegler, & Zorzi, 2007). CDP++ is able to simulate the reading aloud of mono- and disyllabic words and nonwords, and learns to assign stress in exactly the same way as it learns to associate graphemes with phonemes. CDP++ is able to simulate the monosyllabic benchmark effects its predecessor could, and therefore shows full backwards compatibility. CDP++ also accounts for a number of novel effects specific to disyllabic words, including the effects of stress regularity and syllable number. In terms of database performance, CDP++ accounts for over 49% of the reaction time variance on items selected from the English Lexicon Project, a very large database of several thousand of words. With its lexicon of over 32,000 words, CDP++ is therefore a notable example of the successful scaling-up of a connectionist model to a size that more realistically approximates the human lexical system. PMID:20510406

  8. Phenomenological scattering-rate model for the simulation of the current density and emission power in mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Kurlov, S. S.; Flores, Y. V.; Elagin, M.; Semtsiv, M. P.; Schrottke, L.; Grahn, H. T.; Tarasov, G. G.; Masselink, W. T.

    2016-04-01

    A phenomenological scattering-rate model introduced for terahertz quantum cascade lasers (QCLs) [Schrottke et al., Semicond. Sci. Technol. 25, 045025 (2010)] is extended to mid-infrared (MIR) QCLs by including the energy dependence of the intersubband scattering rates for energies higher than the longitudinal optical phonon energy. This energy dependence is obtained from a phenomenological fit of the intersubband scattering rates based on published lifetimes of a number of MIR QCLs. In our approach, the total intersubband scattering rate is written as the product of the exchange integral for the squared moduli of the envelope functions and a phenomenological factor that depends only on the transition energy. Using the model to calculate scattering rates and imposing periodical boundary conditions on the current density, we find a good agreement with low-temperature data for current-voltage, power-current, and energy-photon flux characteristics for a QCL emitting at 5.2 μm.

  9. 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.

  10. 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

  11. 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. PMID:19899646

  12. 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 =…

  13. 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

  14. Investigating the role of context in learning to read: a direct test of Goodman's model.

    PubMed

    Archer, N; Bryant, P

    2001-11-01

    The much discussed 'whole language' or 'real books' approach to children's reading is based on a theory which makes two quite separate predictions: (1) that children will read difficult words more successfully in context than in isolation, and (2) that contextual experience of words will lead to greater improvements in word reading than isolated experience of words. We report a study which tests both predictions and supports the first but not the second. PMID:11762862

  15. 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…

  16. Reading Recovery.

    ERIC Educational Resources Information Center

    Jones, Joanna R., Ed.

    1992-01-01

    This issue of the Arizona Reading Journal focuses on the theme "reading recovery" and includes the following articles: "Why Is an Inservice Programme for Reading Recovery Teachers Necessary?" (Marie M. Clay); "What Is Reading Recovery?" (Gay Su Pinnell); "Teaching a Hard To Teach Child" (Constance A. Compton); "Reading Recovery in Arizona--A…

  17. Unsteady Euler cascade analysis

    NASA Technical Reports Server (NTRS)

    Liu, Jong-Shang; Sockol, Peter M.

    1989-01-01

    The results of an investigation of the rotor-stator interaction phenomena in turbomachines are presented. Numerical study was carried out by solving the unsteady Euler equations in the blade-to-blade direction for a variety of cascade geometries. The problem of uneven rotor and stator blades is addressed by adopting the tilted time domain technique. Computed solutions are presented and discussed for a NACA 0012 type cascade and the first stage fuel turbopump of the Space Shuttle Main Engine (SSME).

  18. 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…

  19. 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}.

  20. 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.

  1. 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

  2. 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

    2013-07-01

    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

  3. 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.

  4. 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…

  5. A Dynamic Reading-Linking-to-Writing Model for Problem Solving within a Constructive Hypermedia Learning Environment.

    ERIC Educational Resources Information Center

    Yang, Shu Ching

    1996-01-01

    A study of five undergraduates in an introductory course on Greek culture identified novice problem-solving patterns and cognitive processes when using Perseus, a Greek culture database. Discusses the Reading-Linking-to-Writing Model developed to capture procedural and systemic processes used in problem-solving tasks with hypermedia applications.…

  6. 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" have been…

  7. 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…

  8. The Effects of a Composing Model on Fifth Grade Students' Reading Comprehension.

    ERIC Educational Resources Information Center

    Prater, Doris L.; Terry, C. Ann

    A study was conducted to determine whether students who mapped prior and post knowledge of a basal reading lesson would achieve higher scores on a comprehension test and write better summaries of those stories than would students who received traditional basal reading instruction. Subjects, 30 fifth grade students, participated in either a…

  9. A Model for Improving Reading through Music Study in Band and Orchestra.

    ERIC Educational Resources Information Center

    Pearce, Mike

    2000-01-01

    Describes how one middle school band and orchestra teacher, in response to his principal's call for schoolwide attention to improving student literacy, engaged students in reading improvement while also increasing musical knowledge. Describes how students each week read one or more short, music-related articles and complete a brief writing…

  10. A Stage-Sequential Model of Reading Transitions: Evidence from the Early Childhood Longitudinal Study

    ERIC Educational Resources Information Center

    Kaplan, David; Walpole, Sharon

    2005-01-01

    This study uses latent transition analysis to examine reading development across the kindergarten and 1st-grade year. Data include poverty status and dichotomous measures of reading at 4 time points for a large sample of children within the Early Childhood Longitudinal Study. In each of 4 waves of the study, 5 latent classes were represented in…

  11. An Effective Inservice Model for Content Area Reading in Secondary Schools.

    ERIC Educational Resources Information Center

    Dupuis, Mary M.; Askov, Eunice N.

    1982-01-01

    Pennsylvania's Content Area Reading Program uses a network of 50 trained instructors to help teachers improve students' content area reading skills. This article covers program content, instructor recruitment and training, variations in program presentation, factors underlying program success, and steps in planning inservice programs in content…

  12. Correcting Reading and Spelling Difficulties: A Balanced Model for Remedial Education.

    ERIC Educational Resources Information Center

    Valtin, Renate; Naegele, Ingrid M.

    2001-01-01

    Puts reading and spelling difficulties in a cognitive developmental perspective that views the acquisition of reading, writing, and spelling as a sequence of characteristic strategies for dealing with written language. Concludes that the ultimate goal is to reduce the great number of children who fail to acquire literacy due to teachers' lack of…

  13. 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.

  14. A Physics-Based Three Dimensional Model for Write and Read Performances of Phase-Change Probe Memory.

    PubMed

    Wang, Lei; Wright, C David; Aziz, Mustafa M; Ying, Jin; Yang, Guo Wei

    2015-04-01

    The write and read performances of phase-change probe memory were investigated for the first time by a physics-based pure three dimensional model. The written crystalline bit possessed from this developed model demonstrates the potential of phase-change probe memory for ultra-high density, low energy consumption, high data rate, and good readability. The cross-talk effect on the write and read performances of phase-change probe memory, which can not be modelled by previous two dimensional models, is also evaluated. The findings showed that the bit and track pitches should be remained sufficiently long so as to eliminate the undesired interferences. The simulated results exhibited a good agreement with the experimental observations, thus demonstrating the physical reality of the designed model. PMID:26353493

  15. 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…

  16. 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

  17. 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. PMID:26704963

  18. The CpxR/CpxA two-component regulatory system up-regulates the multidrug resistance cascade to facilitate Escherichia coli resistance to a model antimicrobial peptide.

    PubMed

    Weatherspoon-Griffin, Natasha; Yang, Dezhi; Kong, Wei; Hua, Zichun; Shi, Yixin

    2014-11-21

    A genome-wide susceptibility assay was used to identify specific CpxR-dependent genes that facilitate Escherichia coli resistance to a model cationic antimicrobial peptide, protamine. A total of 115 strains from the Keio Collection, each of which contained a deletion at a demonstrated or predicted CpxR/CpxA-dependent locus, were tested for protamine susceptibility. One strain that exhibited high susceptibility carried a deletion of tolC, a gene that encodes the outer membrane component of multiple tripartite multidrug transporters. Concomitantly, two of these efflux systems, AcrAB/TolC and EmrAB/TolC, play major roles in protamine resistance. Activation of the CpxR/CpxA system stimulates mar transcription, suggesting a new regulatory circuit that enhances the multidrug resistance cascade. Tripartite multidrug efflux systems contribute to bacterial resistance to protamine differently from the Tat system. DNase I footprinting analysis demonstrated that the CpxR protein binds to a sequence located in the -35 and -10 regions of mar promoter. This sequence resembles the consensus CpxR binding site, however, on the opposite strand. aroK, a CpxR-dependent gene that encodes a shikimate kinase in the tryptophan biosynthesis pathway, was also found to facilitate protamine resistance. Specific aromatic metabolites from this pathway, such as indole, can stimulate expression of well studied CpxR-dependent genes degP and cpxP, which are not components of the tripartite multidrug transporters. Thus, we propose a novel mechanism for E. coli to modulate resistance to protamine and likely other cationic antimicrobial peptides in which the CpxR/CpxA system up-regulates mar transcription in response to specific aromatic metabolites, subsequently stimulating the multidrug resistance cascade. PMID:25294881

  19. 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

  20. Reading Comics

    ERIC Educational Resources Information Center

    Tilley, Carol L.

    2008-01-01

    Many adults, even librarians who willingly add comics to their collections, often dismiss the importance of comics. Compared to reading "real" books, reading comics appears to be a simple task and compared to reading no books, reading comics might be preferable. After all, comics do have words, but the plentiful pictures seem to carry most of the…

  1. Reading Rituals

    ERIC Educational Resources Information Center

    Manzo, Kathleen Kennedy

    2007-01-01

    The Ogden, Utah schools have used the mandates of the federal Reading First grant program to transform reading instruction and student achievement in low-performing schools. Reading First was approved by Congress in 2001 under the No Child Left Behind Act to bring scientifically based reading methods and materials to struggling schools. The $1…

  2. Modeling the Response of an Extraordinary Magnetoresistance (EMR) Magnetic Read-head

    NASA Astrophysics Data System (ADS)

    Ram-Mohan, L. R.; Moussa, J.; Solin, S. A.; Rowe, A. C. H.

    2002-03-01

    A finite element approach to the modeling of extraordinary magnetoresistance (EMR)(S.A. Solin et al., Science 289), 1530 (2000). in a 4-terminal circular semiconductor wafer with a central concentric metallic inhomogeneity, which acts as a metal shunt, was reported earlier.(J. Moussa, L. R. Ram-Mohan, J. Sullivan, T. Zhou, D. R. Hines, and S. A. Solin, Physical Review B64), 184410 (2001). Here we present new results on more complex externally shunted van der Pauw plate geometries(T. Zhou, D.R. Hines and S.A. Solin, Appl. Phys. Letter 78), 667 (2001). for the semiconductor/metal shunt structures. The response at the voltage leads is evaluated for a constant current through the two outer leads in a 4-contact arrangement, and the results suggest geometry-dependent variations to the EMR as the shunt geometry is altered. The effect of a localized magnetic field moving over a semiconductor bar attached to a metal shunt on the EMR is reported. The results demonstrate the significant advantages of the semiconductor/shunt arrangement over conventional magnetic structures such as those based on GMR and TMR used as read-heads in digital data storage systems.

  3. Collisional Cascades Revisited

    NASA Astrophysics Data System (ADS)

    Schlichting, Hilke; Pan, M.

    2013-01-01

    Collisional cascades are believed to be the primary mechanism operating in circumstellar dusty debris disks, and are thought to be important in the Kuiper and Asteroid belt. Collisional cascades transfer mass via destructive collisions from larger bodies to smaller ones. Their widespread occurrence and potential importance in understanding planet formation and planet-disk interactions have motivated detailed studies of collisional cascades. The standard theoretical treatment of collisional cascades derives a steady-state size distribution assuming a single constant velocity dispersion for all bodies regardless of size. We relax this assumption and solve self-consistently for the bodies' steady-state size and size-dependent velocity distributions. Specifically, we account for viscous stirring, dynamical friction, and collisional damping of the bodies' random velocities in addition to the mass conservation requirement typically applied to find the size distribution in a steady-state cascade. The resulting size distributions are significantly steeper than those derived without velocity evolution. For example, accounting self-consistently for the velocities can change the standard q = 3.5 power-law index of the Dohnanyi differential size spectrum to an index as large as q = 4. Similarly, for bodies held together by their own gravity, the corresponding power-law index range 2.88 < q < 3.14 of Pan & Sari (2005) can steepen to values as large as q = 3.26. These differences in the size distribution power law index are very important when estimating the total disk mass, including larger bodies, by extrapolating from the observed dust masses. Our velocity results allow quantitative predictions of the bodies' scale heights as a function of size. Together with our predictions, observations of the scale heights for different-sized bodies in, for example, extrasolar debris disks may constrain the total mass in large bodies stirring the cascade as well as the colliding bodies

  4. The Geant4 Bertini Cascade

    NASA Astrophysics Data System (ADS)

    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.

  5. 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.

  6. Chinese College Test Takers' Individual Differences and Reading Test Performance: A Structural Equation Modeling Approach.

    PubMed

    Zhang, Limei

    2016-06-01

    This study reports on the relationships between test takers' individual differences and their performance on a reading comprehension test. A total of 518 Chinese college students (252 women and 256 men; M age = 19.26 year, SD = 0.98) answered a questionnaire and sit for a reading comprehension test. The study found that test takers' L2 language proficiency was closely linked to their test performance. Test takers' employment of strategies was significantly and positively associated with their performance on the test. Test takers' motivation was found to be significantly associated with reading test performance. Test anxiety was negatively related to their use of reading strategies and test performance. The results of the study lent support to the threshold hypothesis of language proficiency. The implications for classroom teaching were provided. PMID:27173665

  7. Intra Nucleon Cascade Program

    Energy Science and Technology Software Center (ESTSC)

    1998-08-18

    The package consists of three programs ISABEL, EVA, and PACE-2. ISABEL and PACE-2 are part of the LAHET code. ISABEL is an intra-nucleon cascade program. The output cascades are used as directly as input files to the two evaporation programs EVA and PACE-2. EVA ignores the effect of the angular momentum of the excited nuclei on the deexcitation and also ignores the possibility of gamma emission as long as particle emission is energetically allowed. PACE-2more » takes full account of angular momentum effects including irast levels and gamma emission at all stages of the evaporation chain.« less

  8. 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.

  9. Unraveling low-resolution structural data of large biomolecules by constructing atomic models with experiment-targeted parallel cascade selection simulations

    PubMed Central

    Peng, Junhui; Zhang, Zhiyong

    2016-01-01

    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. PMID:27377017

  10. Unraveling low-resolution structural data of large biomolecules by constructing atomic models with experiment-targeted parallel cascade selection simulations.

    PubMed

    Peng, Junhui; Zhang, Zhiyong

    2016-01-01

    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. PMID:27377017

  11. Savoring Reading Schoolwide

    ERIC Educational Resources Information Center

    Reis, Sally M.; Fogarty, Elizabeth A.

    2006-01-01

    Over the past four years, educators and researchers from the University of Connecticut have worked with urban high-poverty schools to implement an alternative reading instruction program called the Schoolwide Enrichment Model in Reading (SEM-R). Based on Renzulli's Enrichment Triad Model, the SEM-R works through planned enrichment experiences to…

  12. Cross-Cultural Reading Comprehension Assessment in Malay and English as It Relates to the Dagostino-Carifio Model of Reading Comprehension

    ERIC Educational Resources Information Center

    Dagostino, Lorraine; Carifio, James; Bauer, Jennifer D. C.; Zhao, Qing

    2013-01-01

    The review of existing literature suggests that few researchers have adopted cross-language comparisons to explore how cultural background affects the assessment of reading comprehension of students. In this present study, the researchers independently reviewed and rated all the items of two reading comprehension tests translated from Malay into…

  13. Parent Education for Dialogic Reading during Shared Storybook Reading: Multiple Case Study of Online and Face-to-Face Delivery Models

    ERIC Educational Resources Information Center

    Beschorner, Beth

    2013-01-01

    This study examined the impact of a parent education program on the frequency of shared storybook reading and dialogic reading techniques. Additionally, the contextual factors that influenced the outcomes of the program were explored. Seventeen parents completed a nine-week face-to-face parent education program and fifteen parents completed a…

  14. 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.

  15. 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

  16. Developmental changes in reading do not alter the development of visual processing skills: an application of explanatory item response models in grades K-2

    PubMed Central

    Santi, Kristi L.; Kulesz, Paulina A.; Khalaf, Shiva; Francis, David J.

    2015-01-01

    Visual processing has been widely studied in regard to its impact on a students’ ability to read. A less researched area is the role of reading in the development of visual processing skills. A cohort-sequential, accelerated-longitudinal design was utilized with 932 kindergarten, first, and second grade students to examine the impact of reading acquisition on the processing of various types of visual discrimination and visual motor test items. Students were assessed four times per year on a variety of reading measures and reading precursors and two popular measures of visual processing over a 3-year period. Explanatory item response models were used to examine the roles of person and item characteristics on changes in visual processing abilities and changes in item difficulties over time. Results showed different developmental patterns for five types of visual processing test items, but most importantly failed to show consistent effects of learning to read on changes in item difficulty. Thus, the present study failed to find support for the hypothesis that learning to read alters performance on measures of visual processing. Rather, visual processing and reading ability improved together over time with no evidence to suggest cross-domain influences from reading to visual processing. Results are discussed in the context of developmental theories of visual processing and brain-based research on the role of visual skills in learning to read. PMID:25717311

  17. Developmental changes in reading do not alter the development of visual processing skills: an application of explanatory item response models in grades K-2.

    PubMed

    Santi, Kristi L; Kulesz, Paulina A; Khalaf, Shiva; Francis, David J

    2015-01-01

    Visual processing has been widely studied in regard to its impact on a students' ability to read. A less researched area is the role of reading in the development of visual processing skills. A cohort-sequential, accelerated-longitudinal design was utilized with 932 kindergarten, first, and second grade students to examine the impact of reading acquisition on the processing of various types of visual discrimination and visual motor test items. Students were assessed four times per year on a variety of reading measures and reading precursors and two popular measures of visual processing over a 3-year period. Explanatory item response models were used to examine the roles of person and item characteristics on changes in visual processing abilities and changes in item difficulties over time. Results showed different developmental patterns for five types of visual processing test items, but most importantly failed to show consistent effects of learning to read on changes in item difficulty. Thus, the present study failed to find support for the hypothesis that learning to read alters performance on measures of visual processing. Rather, visual processing and reading ability improved together over time with no evidence to suggest cross-domain influences from reading to visual processing. Results are discussed in the context of developmental theories of visual processing and brain-based research on the role of visual skills in learning to read. PMID:25717311

  18. Un Programa Personalizado De Lectura En Un Aula Primaria: Reporte De Un Modelo Comprobado (A Personalized Program of Reading in a First Grade Classroom: Report From a Proven Model.)

    ERIC Educational Resources Information Center

    Mendenhall, Susie B.; And Others

    This document written in Spanish describes a personalized reading program and discusses the results of its implementation. The focus of this approach to reading is based on the individual child and his feelings. This model personalizes the child's reading material in the classroom. In personalizing the reading material, the child's attitudes…

  19. 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.

  20. '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. ...