A Posteriori Finite Element Bounds for Sensitivity Derivatives of Partial-Differential-Equation Outputs. Revised

NASA Technical Reports Server (NTRS)

Lewis, Robert Michael; Patera, Anthony T.; Peraire, Jaume

1998-01-01

We present a Neumann-subproblem a posteriori finite element procedure for the efficient and accurate calculation of rigorous, 'constant-free' upper and lower bounds for sensitivity derivatives of functionals of the solutions of partial differential equations. The design motivation for sensitivity derivative error control is discussed; the a posteriori finite element procedure is described; the asymptotic bounding properties and computational complexity of the method are summarized; and illustrative numerical results are presented.

An Analysis of a Finite Element Method for Convection-Diffusion Problems. Part II. A Posteriori Error Estimates and Adaptivity.

DTIC Science & Technology

1983-03-01

AN ANALYSIS OF A FINITE ELEMENT METHOD FOR CONVECTION- DIFFUSION PROBLEMS PART II: A POSTERIORI ERROR ESTIMATES AND ADAPTIVITY by W. G. Szymczak Y 6a...PERIOD COVERED AN ANALYSIS OF A FINITE ELEMENT METHOD FOR final life of the contract CONVECTION- DIFFUSION PROBLEM S. Part II: A POSTERIORI ERROR ...Element Method for Convection- Diffusion Problems. Part II: A Posteriori Error Estimates and Adaptivity W. G. Szvmczak and I. Babu~ka# Laboratory for

A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

PubMed Central

Chibinski, Ana Cláudia; Coelho, Ulisses; Wambier, Letícia Stadler; Zedebski, Rosário de Arruda Moura; de Moraes, Mari Eli Leonelli; de Moraes, Luiz Cesar

2016-01-01

Purpose This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. Materials and Methods A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. Results The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. Conclusion A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment. PMID:27051635

Influence of Choice of Null Network on Small-World Parameters of Structural Correlation Networks

PubMed Central

Hosseini, S. M. Hadi; Kesler, Shelli R.

2013-01-01

In recent years, coordinated variations in brain morphology (e.g., volume, thickness) have been employed as a measure of structural association between brain regions to infer large-scale structural correlation networks. Recent evidence suggests that brain networks constructed in this manner are inherently more clustered than random networks of the same size and degree. Thus, null networks constructed by randomizing topology are not a good choice for benchmarking small-world parameters of these networks. In the present report, we investigated the influence of choice of null networks on small-world parameters of gray matter correlation networks in healthy individuals and survivors of acute lymphoblastic leukemia. Three types of null networks were studied: 1) networks constructed by topology randomization (TOP), 2) networks matched to the distributional properties of the observed covariance matrix (HQS), and 3) networks generated from correlation of randomized input data (COR). The results revealed that the choice of null network not only influences the estimated small-world parameters, it also influences the results of between-group differences in small-world parameters. In addition, at higher network densities, the choice of null network influences the direction of group differences in network measures. Our data suggest that the choice of null network is quite crucial for interpretation of group differences in small-world parameters of structural correlation networks. We argue that none of the available null models is perfect for estimation of small-world parameters for correlation networks and the relative strengths and weaknesses of the selected model should be carefully considered with respect to obtained network measures. PMID:23840672

Maximum a posteriori decoder for digital communications

NASA Technical Reports Server (NTRS)

Altes, Richard A. (Inventor)

1997-01-01

A system and method for decoding by identification of the most likely phase coded signal corresponding to received data. The present invention has particular application to communication with signals that experience spurious random phase perturbations. The generalized estimator-correlator uses a maximum a posteriori (MAP) estimator to generate phase estimates for correlation with incoming data samples and for correlation with mean phases indicative of unique hypothesized signals. The result is a MAP likelihood statistic for each hypothesized transmission, wherein the highest value statistic identifies the transmitted signal.

Application of the a posteriori granddaughter design to the Holstein genome

USDA-ARS?s Scientific Manuscript database

An a posteriori granddaughter design was applied to determine haplotype effects for the Holstein genome. A total of 52 grandsire families, each with >=100 genotyped sons with genetic evaluations based on progeny tests, were analyzed for 33 traits (milk, fat, and protein yields; fat and protein perce...

Automatic simplification of systems of reaction-diffusion equations by a posteriori analysis.

PubMed

Maybank, Philip J; Whiteley, Jonathan P

2014-02-01

Many mathematical models in biology and physiology are represented by systems of nonlinear differential equations. In recent years these models have become increasingly complex in order to explain the enormous volume of data now available. A key role of modellers is to determine which components of the model have the greatest effect on a given observed behaviour. An approach for automatically fulfilling this role, based on a posteriori analysis, has recently been developed for nonlinear initial value ordinary differential equations [J.P. Whiteley, Model reduction using a posteriori analysis, Math. Biosci. 225 (2010) 44-52]. In this paper we extend this model reduction technique for application to both steady-state and time-dependent nonlinear reaction-diffusion systems. Exemplar problems drawn from biology are used to demonstrate the applicability of the technique. Copyright © 2014 Elsevier Inc. All rights reserved.

An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography

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

Feng Jinchao; Qin Chenghu; Jia Kebin

2011-11-15

Purpose: Bioluminescence tomography (BLT) provides an effective tool for monitoring physiological and pathological activities in vivo. However, the measured data in bioluminescence imaging are corrupted by noise. Therefore, regularization methods are commonly used to find a regularized solution. Nevertheless, for the quality of the reconstructed bioluminescent source obtained by regularization methods, the choice of the regularization parameters is crucial. To date, the selection of regularization parameters remains challenging. With regards to the above problems, the authors proposed a BLT reconstruction algorithm with an adaptive parameter choice rule. Methods: The proposed reconstruction algorithm uses a diffusion equation for modeling the bioluminescentmore » photon transport. The diffusion equation is solved with a finite element method. Computed tomography (CT) images provide anatomical information regarding the geometry of the small animal and its internal organs. To reduce the ill-posedness of BLT, spectral information and the optimal permissible source region are employed. Then, the relationship between the unknown source distribution and multiview and multispectral boundary measurements is established based on the finite element method and the optimal permissible source region. Since the measured data are noisy, the BLT reconstruction is formulated as l{sub 2} data fidelity and a general regularization term. When choosing the regularization parameters for BLT, an efficient model function approach is proposed, which does not require knowledge of the noise level. This approach only requests the computation of the residual and regularized solution norm. With this knowledge, we construct the model function to approximate the objective function, and the regularization parameter is updated iteratively. Results: First, the micro-CT based mouse phantom was used for simulation verification. Simulation experiments were used to illustrate why multispectral data

Extracting volatility signal using maximum a posteriori estimation

NASA Astrophysics Data System (ADS)

Neto, David

2016-11-01

This paper outlines a methodology to estimate a denoised volatility signal for foreign exchange rates using a hidden Markov model (HMM). For this purpose a maximum a posteriori (MAP) estimation is performed. A double exponential prior is used for the state variable (the log-volatility) in order to allow sharp jumps in realizations and then log-returns marginal distributions with heavy tails. We consider two routes to choose the regularization and we compare our MAP estimate to realized volatility measure for three exchange rates.

A posteriori model validation for the temporal order of directed functional connectivity maps

PubMed Central

Beltz, Adriene M.; Molenaar, Peter C. M.

2015-01-01

A posteriori model validation for the temporal order of neural directed functional connectivity maps is rare. This is striking because models that require sequential independence among residuals are regularly implemented. The aim of the current study was (a) to apply to directed functional connectivity maps of functional magnetic resonance imaging data an a posteriori model validation procedure (i.e., white noise tests of one-step-ahead prediction errors combined with decision criteria for revising the maps based upon Lagrange Multiplier tests), and (b) to demonstrate how the procedure applies to single-subject simulated, single-subject task-related, and multi-subject resting state data. Directed functional connectivity was determined by the unified structural equation model family of approaches in order to map contemporaneous and first order lagged connections among brain regions at the group- and individual-levels while incorporating external input, then white noise tests were run. Findings revealed that the validation procedure successfully detected unmodeled sequential dependencies among residuals and recovered higher order (greater than one) simulated connections, and that the procedure can accommodate task-related input. Findings also revealed that lags greater than one were present in resting state data: With a group-level network that contained only contemporaneous and first order connections, 44% of subjects required second order, individual-level connections in order to obtain maps with white noise residuals. Results have broad methodological relevance (e.g., temporal validation is necessary after directed functional connectivity analyses because the presence of unmodeled higher order sequential dependencies may bias parameter estimates) and substantive implications (e.g., higher order lags may be common in resting state data). PMID:26379489

A posteriori model validation for the temporal order of directed functional connectivity maps.

PubMed

Beltz, Adriene M; Molenaar, Peter C M

2015-01-01

A posteriori model validation for the temporal order of neural directed functional connectivity maps is rare. This is striking because models that require sequential independence among residuals are regularly implemented. The aim of the current study was (a) to apply to directed functional connectivity maps of functional magnetic resonance imaging data an a posteriori model validation procedure (i.e., white noise tests of one-step-ahead prediction errors combined with decision criteria for revising the maps based upon Lagrange Multiplier tests), and (b) to demonstrate how the procedure applies to single-subject simulated, single-subject task-related, and multi-subject resting state data. Directed functional connectivity was determined by the unified structural equation model family of approaches in order to map contemporaneous and first order lagged connections among brain regions at the group- and individual-levels while incorporating external input, then white noise tests were run. Findings revealed that the validation procedure successfully detected unmodeled sequential dependencies among residuals and recovered higher order (greater than one) simulated connections, and that the procedure can accommodate task-related input. Findings also revealed that lags greater than one were present in resting state data: With a group-level network that contained only contemporaneous and first order connections, 44% of subjects required second order, individual-level connections in order to obtain maps with white noise residuals. Results have broad methodological relevance (e.g., temporal validation is necessary after directed functional connectivity analyses because the presence of unmodeled higher order sequential dependencies may bias parameter estimates) and substantive implications (e.g., higher order lags may be common in resting state data).

[Methods of a posteriori identification of food patterns in Brazilian children: a systematic review].

PubMed

Carvalho, Carolina Abreu de; Fonsêca, Poliana Cristina de Almeida; Nobre, Luciana Neri; Priore, Silvia Eloiza; Franceschini, Sylvia do Carmo Castro

2016-01-01

The objective of this study is to provide guidance for identifying dietary patterns using the a posteriori approach, and analyze the methodological aspects of the studies conducted in Brazil that identified the dietary patterns of children. Articles were selected from the Latin American and Caribbean Literature on Health Sciences, Scientific Electronic Library Online and Pubmed databases. The key words were: Dietary pattern; Food pattern; Principal Components Analysis; Factor analysis; Cluster analysis; Reduced rank regression. We included studies that identified dietary patterns of children using the a posteriori approach. Seven studies published between 2007 and 2014 were selected, six of which were cross-sectional and one cohort, Five studies used the food frequency questionnaire for dietary assessment; one used a 24-hour dietary recall and the other a food list. The method of exploratory approach used in most publications was principal components factor analysis, followed by cluster analysis. The sample size of the studies ranged from 232 to 4231, the values of the Kaiser-Meyer-Olkin test from 0.524 to 0.873, and Cronbach's alpha from 0.51 to 0.69. Few Brazilian studies identified dietary patterns of children using the a posteriori approach and principal components factor analysis was the technique most used.

On the Least-Squares Fitting of Correlated Data: a Priorivs a PosterioriWeighting

NASA Astrophysics Data System (ADS)

Tellinghuisen, Joel

1996-10-01

One of the methods in common use for analyzing large data sets is a two-step procedure, in which subsets of the full data are first least-squares fitted to a preliminary set of parameters, and the latter are subsequently merged to yield the final parameters. The second step of this procedure is properly a correlated least-squares fit and requires the variance-covariance matrices from the first step to construct the weight matrix for the merge. There is, however, an ambiguity concerning the manner in which the first-step variance-covariance matrices are assessed, which leads to different statistical properties for the quantities determined in the merge. The issue is one ofa priorivsa posterioriassessment of weights, which is an application of what was originally calledinternalvsexternal consistencyby Birge [Phys. Rev.40,207-227 (1932)] and Deming ("Statistical Adjustment of Data." Dover, New York, 1964). In the present work the simplest case of a merge fit-that of an average as obtained from a global fit vs a two-step fit of partitioned data-is used to illustrate that only in the case of a priori weighting do the results have the usually expected and desired statistical properties: normal distributions for residuals,tdistributions for parameters assessed a posteriori, and χ2distributions for variances.

A POSTERIORI ERROR ANALYSIS OF TWO STAGE COMPUTATION METHODS WITH APPLICATION TO EFFICIENT DISCRETIZATION AND THE PARAREAL ALGORITHM.

PubMed

Chaudhry, Jehanzeb Hameed; Estep, Don; Tavener, Simon; Carey, Varis; Sandelin, Jeff

2016-01-01

We consider numerical methods for initial value problems that employ a two stage approach consisting of solution on a relatively coarse discretization followed by solution on a relatively fine discretization. Examples include adaptive error control, parallel-in-time solution schemes, and efficient solution of adjoint problems for computing a posteriori error estimates. We describe a general formulation of two stage computations then perform a general a posteriori error analysis based on computable residuals and solution of an adjoint problem. The analysis accommodates various variations in the two stage computation and in formulation of the adjoint problems. We apply the analysis to compute "dual-weighted" a posteriori error estimates, to develop novel algorithms for efficient solution that take into account cancellation of error, and to the Parareal Algorithm. We test the various results using several numerical examples.

Nestly--a framework for running software with nested parameter choices and aggregating results.

PubMed

McCoy, Connor O; Gallagher, Aaron; Hoffman, Noah G; Matsen, Frederick A

2013-02-01

The execution of a software application or pipeline using various combinations of parameters and inputs is a common task in bioinformatics. In the absence of a specialized tool to organize, streamline and formalize this process, scientists must write frequently complex scripts to perform these tasks. We present nestly, a Python package to facilitate running tools with nested combinations of parameters and inputs. nestly provides three components. First, a module to build nested directory structures corresponding to choices of parameters. Second, the nestrun script to run a given command using each set of parameter choices. Third, the nestagg script to aggregate results of the individual runs into a CSV file, as well as support for more complex aggregation. We also include a module for easily specifying nested dependencies for the SCons build tool, enabling incremental builds. Source, documentation and tutorial examples are available at http://github.com/fhcrc/nestly. nestly can be installed from the Python Package Index via pip; it is open source (MIT license).

Analysis of the geophysical data using a posteriori algorithms

NASA Astrophysics Data System (ADS)

Voskoboynikova, Gyulnara; Khairetdinov, Marat

2016-04-01

The problems of monitoring, prediction and prevention of extraordinary natural and technogenic events are priority of modern problems. These events include earthquakes, volcanic eruptions, the lunar-solar tides, landslides, falling celestial bodies, explosions utilized stockpiles of ammunition, numerous quarry explosion in open coal mines, provoking technogenic earthquakes. Monitoring is based on a number of successive stages, which include remote registration of the events responses, measurement of the main parameters as arrival times of seismic waves or the original waveforms. At the final stage the inverse problems associated with determining the geographic location and time of the registration event are solving. Therefore, improving the accuracy of the parameters estimation of the original records in the high noise is an important problem. As is known, the main measurement errors arise due to the influence of external noise, the difference between the real and model structures of the medium, imprecision of the time definition in the events epicenter, the instrumental errors. Therefore, posteriori algorithms more accurate in comparison with known algorithms are proposed and investigated. They are based on a combination of discrete optimization method and fractal approach for joint detection and estimation of the arrival times in the quasi-periodic waveforms sequence in problems of geophysical monitoring with improved accuracy. Existing today, alternative approaches to solving these problems does not provide the given accuracy. The proposed algorithms are considered for the tasks of vibration sounding of the Earth in times of lunar and solar tides, and for the problem of monitoring of the borehole seismic source location in trade drilling.

Combined Uncertainty and A-Posteriori Error Bound Estimates for General CFD Calculations: Theory and Software Implementation

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

2014-01-01

This workshop presentation discusses the design and implementation of numerical methods for the quantification of statistical uncertainty, including a-posteriori error bounds, for output quantities computed using CFD methods. Hydrodynamic realizations often contain numerical error arising from finite-dimensional approximation (e.g. numerical methods using grids, basis functions, particles) and statistical uncertainty arising from incomplete information and/or statistical characterization of model parameters and random fields. The first task at hand is to derive formal error bounds for statistics given realizations containing finite-dimensional numerical error [1]. The error in computed output statistics contains contributions from both realization error and the error resulting from the calculation of statistics integrals using a numerical method. A second task is to devise computable a-posteriori error bounds by numerically approximating all terms arising in the error bound estimates. For the same reason that CFD calculations including error bounds but omitting uncertainty modeling are only of limited value, CFD calculations including uncertainty modeling but omitting error bounds are only of limited value. To gain maximum value from CFD calculations, a general software package for uncertainty quantification with quantified error bounds has been developed at NASA. The package provides implementations for a suite of numerical methods used in uncertainty quantification: Dense tensorization basis methods [3] and a subscale recovery variant [1] for non-smooth data, Sparse tensorization methods[2] utilizing node-nested hierarchies, Sampling methods[4] for high-dimensional random variable spaces.

Influence of Context on Item Parameters in Forced-Choice Personality Assessments

ERIC Educational Resources Information Center

Lin, Yin; Brown, Anna

2017-01-01

A fundamental assumption in computerized adaptive testing is that item parameters are invariant with respect to context--items surrounding the administered item. This assumption, however, may not hold in forced-choice (FC) assessments, where explicit comparisons are made between items included in the same block. We empirically examined the…

Optimization of a centrifugal compressor impeller using CFD: the choice of simulation model parameters

NASA Astrophysics Data System (ADS)

Neverov, V. V.; Kozhukhov, Y. V.; Yablokov, A. M.; Lebedev, A. A.

2017-08-01

Nowadays the optimization using computational fluid dynamics (CFD) plays an important role in the design process of turbomachines. However, for the successful and productive optimization it is necessary to define a simulation model correctly and rationally. The article deals with the choice of a grid and computational domain parameters for optimization of centrifugal compressor impellers using computational fluid dynamics. Searching and applying optimal parameters of the grid model, the computational domain and solver settings allows engineers to carry out a high-accuracy modelling and to use computational capability effectively. The presented research was conducted using Numeca Fine/Turbo package with Spalart-Allmaras and Shear Stress Transport turbulence models. Two radial impellers was investigated: the high-pressure at ψT=0.71 and the low-pressure at ψT=0.43. The following parameters of the computational model were considered: the location of inlet and outlet boundaries, type of mesh topology, size of mesh and mesh parameter y+. Results of the investigation demonstrate that the choice of optimal parameters leads to the significant reduction of the computational time. Optimal parameters in comparison with non-optimal but visually similar parameters can reduce the calculation time up to 4 times. Besides, it is established that some parameters have a major impact on the result of modelling.

The role of a posteriori mathematics in physics

NASA Astrophysics Data System (ADS)

MacKinnon, Edward

2018-05-01

The calculus that co-evolved with classical mechanics relied on definitions of functions and differentials that accommodated physical intuitions. In the early nineteenth century mathematicians began the rigorous reformulation of calculus and eventually succeeded in putting almost all of mathematics on a set-theoretic foundation. Physicists traditionally ignore this rigorous mathematics. Physicists often rely on a posteriori math, a practice of using physical considerations to determine mathematical formulations. This is illustrated by examples from classical and quantum physics. A justification of such practice stems from a consideration of the role of phenomenological theories in classical physics and effective theories in contemporary physics. This relates to the larger question of how physical theories should be interpreted.

Weighted Maximum-a-Posteriori Estimation in Tests Composed of Dichotomous and Polytomous Items

ERIC Educational Resources Information Center

Sun, Shan-Shan; Tao, Jian; Chang, Hua-Hua; Shi, Ning-Zhong

2012-01-01

For mixed-type tests composed of dichotomous and polytomous items, polytomous items often yield more information than dichotomous items. To reflect the difference between the two types of items and to improve the precision of ability estimation, an adaptive weighted maximum-a-posteriori (WMAP) estimation is proposed. To evaluate the performance of…

A twofold quantum delayed-choice experiment in a superconducting circuit.

PubMed

Liu, Ke; Xu, Yuan; Wang, Weiting; Zheng, Shi-Biao; Roy, Tanay; Kundu, Suman; Chand, Madhavi; Ranadive, Arpit; Vijay, Rajamani; Song, Yipu; Duan, Luming; Sun, Luyan

2017-05-01

Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.

The Multiple-Choice Model: Some Solutions for Estimation of Parameters in the Presence of Omitted Responses

ERIC Educational Resources Information Center

Abad, Francisco J.; Olea, Julio; Ponsoda, Vicente

2009-01-01

This article deals with some of the problems that have hindered the application of Samejima's and Thissen and Steinberg's multiple-choice models: (a) parameter estimation difficulties owing to the large number of parameters involved, (b) parameter identifiability problems in the Thissen and Steinberg model, and (c) their treatment of omitted…

Adaptive-Mesh-Refinement for hyperbolic systems of conservation laws based on a posteriori stabilized high order polynomial reconstructions

NASA Astrophysics Data System (ADS)

Semplice, Matteo; Loubère, Raphaël

2018-02-01

In this paper we propose a third order accurate finite volume scheme based on a posteriori limiting of polynomial reconstructions within an Adaptive-Mesh-Refinement (AMR) simulation code for hydrodynamics equations in 2D. The a posteriori limiting is based on the detection of problematic cells on a so-called candidate solution computed at each stage of a third order Runge-Kutta scheme. Such detection may include different properties, derived from physics, such as positivity, from numerics, such as a non-oscillatory behavior, or from computer requirements such as the absence of NaN's. Troubled cell values are discarded and re-computed starting again from the previous time-step using a more dissipative scheme but only locally, close to these cells. By locally decrementing the degree of the polynomial reconstructions from 2 to 0 we switch from a third-order to a first-order accurate but more stable scheme. The entropy indicator sensor is used to refine/coarsen the mesh. This sensor is also employed in an a posteriori manner because if some refinement is needed at the end of a time step, then the current time-step is recomputed with the refined mesh, but only locally, close to the new cells. We show on a large set of numerical tests that this a posteriori limiting procedure coupled with the entropy-based AMR technology can maintain not only optimal accuracy on smooth flows but also stability on discontinuous profiles such as shock waves, contacts, interfaces, etc. Moreover numerical evidences show that this approach is at least comparable in terms of accuracy and cost to a more classical CWENO approach within the same AMR context.

A Posteriori Error Estimation for Discontinuous Galerkin Approximations of Hyperbolic Systems

NASA Technical Reports Server (NTRS)

Larson, Mats G.; Barth, Timothy J.

1999-01-01

This article considers a posteriori error estimation of specified functionals for first-order systems of conservation laws discretized using the discontinuous Galerkin (DG) finite element method. Using duality techniques, we derive exact error representation formulas for both linear and nonlinear functionals given an associated bilinear or nonlinear variational form. Weighted residual approximations of the exact error representation formula are then proposed and numerically evaluated for Ringleb flow, an exact solution of the 2-D Euler equations.

A Two-Stage Algorithm for Origin-Destination Matrices Estimation Considering Dynamic Dispersion Parameter for Route Choice

PubMed Central

Wang, Yong; Ma, Xiaolei; Liu, Yong; Gong, Ke; Henricakson, Kristian C.; Xu, Maozeng; Wang, Yinhai

2016-01-01

This paper proposes a two-stage algorithm to simultaneously estimate origin-destination (OD) matrix, link choice proportion, and dispersion parameter using partial traffic counts in a congested network. A non-linear optimization model is developed which incorporates a dynamic dispersion parameter, followed by a two-stage algorithm in which Generalized Least Squares (GLS) estimation and a Stochastic User Equilibrium (SUE) assignment model are iteratively applied until the convergence is reached. To evaluate the performance of the algorithm, the proposed approach is implemented in a hypothetical network using input data with high error, and tested under a range of variation coefficients. The root mean squared error (RMSE) of the estimated OD demand and link flows are used to evaluate the model estimation results. The results indicate that the estimated dispersion parameter theta is insensitive to the choice of variation coefficients. The proposed approach is shown to outperform two established OD estimation methods and produce parameter estimates that are close to the ground truth. In addition, the proposed approach is applied to an empirical network in Seattle, WA to validate the robustness and practicality of this methodology. In summary, this study proposes and evaluates an innovative computational approach to accurately estimate OD matrices using link-level traffic flow data, and provides useful insight for optimal parameter selection in modeling travelers’ route choice behavior. PMID:26761209

Enhancing adaptive sparse grid approximations and improving refinement strategies using adjoint-based a posteriori error estimates

DOE PAGES

Jakeman, J. D.; Wildey, T.

2015-01-01

In this paper we present an algorithm for adaptive sparse grid approximations of quantities of interest computed from discretized partial differential equations. We use adjoint-based a posteriori error estimates of the interpolation error in the sparse grid to enhance the sparse grid approximation and to drive adaptivity. We show that utilizing these error estimates provides significantly more accurate functional values for random samples of the sparse grid approximation. We also demonstrate that alternative refinement strategies based upon a posteriori error estimates can lead to further increases in accuracy in the approximation over traditional hierarchical surplus based strategies. Throughout this papermore » we also provide and test a framework for balancing the physical discretization error with the stochastic interpolation error of the enhanced sparse grid approximation.« less

Adaptive vibrational configuration interaction (A-VCI): A posteriori error estimation to efficiently compute anharmonic IR spectra

NASA Astrophysics Data System (ADS)

Garnier, Romain; Odunlami, Marc; Le Bris, Vincent; Bégué, Didier; Baraille, Isabelle; Coulaud, Olivier

2016-05-01

A new variational algorithm called adaptive vibrational configuration interaction (A-VCI) intended for the resolution of the vibrational Schrödinger equation was developed. The main advantage of this approach is to efficiently reduce the dimension of the active space generated into the configuration interaction (CI) process. Here, we assume that the Hamiltonian writes as a sum of products of operators. This adaptive algorithm was developed with the use of three correlated conditions, i.e., a suitable starting space, a criterion for convergence, and a procedure to expand the approximate space. The velocity of the algorithm was increased with the use of a posteriori error estimator (residue) to select the most relevant direction to increase the space. Two examples have been selected for benchmark. In the case of H2CO, we mainly study the performance of A-VCI algorithm: comparison with the variation-perturbation method, choice of the initial space, and residual contributions. For CH3CN, we compare the A-VCI results with a computed reference spectrum using the same potential energy surface and for an active space reduced by about 90%.

Adaptive vibrational configuration interaction (A-VCI): A posteriori error estimation to efficiently compute anharmonic IR spectra.

PubMed

Garnier, Romain; Odunlami, Marc; Le Bris, Vincent; Bégué, Didier; Baraille, Isabelle; Coulaud, Olivier

2016-05-28

A new variational algorithm called adaptive vibrational configuration interaction (A-VCI) intended for the resolution of the vibrational Schrödinger equation was developed. The main advantage of this approach is to efficiently reduce the dimension of the active space generated into the configuration interaction (CI) process. Here, we assume that the Hamiltonian writes as a sum of products of operators. This adaptive algorithm was developed with the use of three correlated conditions, i.e., a suitable starting space, a criterion for convergence, and a procedure to expand the approximate space. The velocity of the algorithm was increased with the use of a posteriori error estimator (residue) to select the most relevant direction to increase the space. Two examples have been selected for benchmark. In the case of H2CO, we mainly study the performance of A-VCI algorithm: comparison with the variation-perturbation method, choice of the initial space, and residual contributions. For CH3CN, we compare the A-VCI results with a computed reference spectrum using the same potential energy surface and for an active space reduced by about 90%.

Maximum a posteriori classification of multifrequency, multilook, synthetic aperture radar intensity data

NASA Technical Reports Server (NTRS)

Rignot, E.; Chellappa, R.

1993-01-01

We present a maximum a posteriori (MAP) classifier for classifying multifrequency, multilook, single polarization SAR intensity data into regions or ensembles of pixels of homogeneous and similar radar backscatter characteristics. A model for the prior joint distribution of the multifrequency SAR intensity data is combined with a Markov random field for representing the interactions between region labels to obtain an expression for the posterior distribution of the region labels given the multifrequency SAR observations. The maximization of the posterior distribution yields Bayes's optimum region labeling or classification of the SAR data or its MAP estimate. The performance of the MAP classifier is evaluated by using computer-simulated multilook SAR intensity data as a function of the parameters in the classification process. Multilook SAR intensity data are shown to yield higher classification accuracies than one-look SAR complex amplitude data. The MAP classifier is extended to the case in which the radar backscatter from the remotely sensed surface varies within the SAR image because of incidence angle effects. The results obtained illustrate the practicality of the method for combining SAR intensity observations acquired at two different frequencies and for improving classification accuracy of SAR data.

Enhancing adaptive sparse grid approximations and improving refinement strategies using adjoint-based a posteriori error estimates

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

Jakeman, J.D., E-mail: jdjakem@sandia.gov; Wildey, T.

2015-01-01

In this paper we present an algorithm for adaptive sparse grid approximations of quantities of interest computed from discretized partial differential equations. We use adjoint-based a posteriori error estimates of the physical discretization error and the interpolation error in the sparse grid to enhance the sparse grid approximation and to drive adaptivity of the sparse grid. Utilizing these error estimates provides significantly more accurate functional values for random samples of the sparse grid approximation. We also demonstrate that alternative refinement strategies based upon a posteriori error estimates can lead to further increases in accuracy in the approximation over traditional hierarchicalmore » surplus based strategies. Throughout this paper we also provide and test a framework for balancing the physical discretization error with the stochastic interpolation error of the enhanced sparse grid approximation.« less

A twofold quantum delayed-choice experiment in a superconducting circuit

PubMed Central

Liu, Ke; Xu, Yuan; Wang, Weiting; Zheng, Shi-Biao; Roy, Tanay; Kundu, Suman; Chand, Madhavi; Ranadive, Arpit; Vijay, Rajamani; Song, Yipu; Duan, Luming; Sun, Luyan

2017-01-01

Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system’s path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system’s behavior depends not only on the measuring device’s configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment. PMID:28508079

A posteriori noise estimation in variable data sets. With applications to spectra and light curves

NASA Astrophysics Data System (ADS)

Czesla, S.; Molle, T.; Schmitt, J. H. M. M.

2018-01-01

Most physical data sets contain a stochastic contribution produced by measurement noise or other random sources along with the signal. Usually, neither the signal nor the noise are accurately known prior to the measurement so that both have to be estimated a posteriori. We have studied a procedure to estimate the standard deviation of the stochastic contribution assuming normality and independence, requiring a sufficiently well-sampled data set to yield reliable results. This procedure is based on estimating the standard deviation in a sample of weighted sums of arbitrarily sampled data points and is identical to the so-called DER_SNR algorithm for specific parameter settings. To demonstrate the applicability of our procedure, we present applications to synthetic data, high-resolution spectra, and a large sample of space-based light curves and, finally, give guidelines to apply the procedure in situation not explicitly considered here to promote its adoption in data analysis.

A posteriori operation detection in evolving software models

PubMed Central

Langer, Philip; Wimmer, Manuel; Brosch, Petra; Herrmannsdörfer, Markus; Seidl, Martina; Wieland, Konrad; Kappel, Gerti

2013-01-01

As every software artifact, also software models are subject to continuous evolution. The operations applied between two successive versions of a model are crucial for understanding its evolution. Generic approaches for detecting operations a posteriori identify atomic operations, but neglect composite operations, such as refactorings, which leads to cluttered difference reports. To tackle this limitation, we present an orthogonal extension of existing atomic operation detection approaches for detecting also composite operations. Our approach searches for occurrences of composite operations within a set of detected atomic operations in a post-processing manner. One major benefit is the reuse of specifications available for executing composite operations also for detecting applications of them. We evaluate the accuracy of the approach in a real-world case study and investigate the scalability of our implementation in an experiment. PMID:23471366

Noise stochastic corrected maximum a posteriori estimator for birefringence imaging using polarization-sensitive optical coherence tomography

PubMed Central

Kasaragod, Deepa; Makita, Shuichi; Hong, Young-Joo; Yasuno, Yoshiaki

2017-01-01

This paper presents a noise-stochastic corrected maximum a posteriori estimator for birefringence imaging using Jones matrix optical coherence tomography. The estimator described in this paper is based on the relationship between probability distribution functions of the measured birefringence and the effective signal to noise ratio (ESNR) as well as the true birefringence and the true ESNR. The Monte Carlo method is used to numerically describe this relationship and adaptive 2D kernel density estimation provides the likelihood for a posteriori estimation of the true birefringence. Improved estimation is shown for the new estimator with stochastic model of ESNR in comparison to the old estimator, both based on the Jones matrix noise model. A comparison with the mean estimator is also done. Numerical simulation validates the superiority of the new estimator. The superior performance of the new estimator was also shown by in vivo measurement of optic nerve head. PMID:28270974

An Iterative Maximum a Posteriori Estimation of Proficiency Level to Detect Multiple Local Likelihood Maxima

ERIC Educational Resources Information Center

Magis, David; Raiche, Gilles

2010-01-01

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The usual maximum a posteriori (MAP) method offers a good alternative within that framework; however, this article highlights some drawbacks of its…

Cosmic shear measurement with maximum likelihood and maximum a posteriori inference

NASA Astrophysics Data System (ADS)

Hall, Alex; Taylor, Andy

2017-06-01

We investigate the problem of noise bias in maximum likelihood and maximum a posteriori estimators for cosmic shear. We derive the leading and next-to-leading order biases and compute them in the context of galaxy ellipticity measurements, extending previous work on maximum likelihood inference for weak lensing. We show that a large part of the bias on these point estimators can be removed using information already contained in the likelihood when a galaxy model is specified, without the need for external calibration. We test these bias-corrected estimators on simulated galaxy images similar to those expected from planned space-based weak lensing surveys, with promising results. We find that the introduction of an intrinsic shape prior can help with mitigation of noise bias, such that the maximum a posteriori estimate can be made less biased than the maximum likelihood estimate. Second-order terms offer a check on the convergence of the estimators, but are largely subdominant. We show how biases propagate to shear estimates, demonstrating in our simple set-up that shear biases can be reduced by orders of magnitude and potentially to within the requirements of planned space-based surveys at mild signal-to-noise ratio. We find that second-order terms can exhibit significant cancellations at low signal-to-noise ratio when Gaussian noise is assumed, which has implications for inferring the performance of shear-measurement algorithms from simplified simulations. We discuss the viability of our point estimators as tools for lensing inference, arguing that they allow for the robust measurement of ellipticity and shear.

Measuring saliency in images: which experimental parameters for the assessment of image quality?

NASA Astrophysics Data System (ADS)

Fredembach, Clement; Woolfe, Geoff; Wang, Jue

2012-01-01

Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a

Volcanic eruption source parameters from active and passive microwave sensors

NASA Astrophysics Data System (ADS)

Montopoli, Mario; Marzano, Frank S.; Cimini, Domenico; Mereu, Luigi

2016-04-01

It is well known, in the volcanology community, that precise information of the source parameters characterising an eruption are of predominant interest for the initialization of the Volcanic Transport and Dispersion Models (VTDM). Source parameters of main interest would be the top altitude of the volcanic plume, the flux of the mass ejected at the emission source, which is strictly related to the cloud top altitude, the distribution of volcanic mass concentration along the vertical column as well as the duration of the eruption and the erupted volume. Usually, the combination of a-posteriori field and numerical studies allow constraining the eruption source parameters for a given volcanic event thus making possible the forecast of ash dispersion and deposition from future volcanic eruptions. So far, remote sensors working at visible and infrared channels (cameras and radiometers) have been mainly used to detect, track and provide estimates of the concentration content and the prevailing size of the particles propagating within the ash clouds up to several thousand of kilometres far from the source as well as track back, a-posteriori, the accuracy of the VATDM outputs thus testing the initial choice made for the source parameters. Acoustic wave (infrasound) and microwave fixed scan radar (voldorad) were also used to infer source parameters. In this work we want to put our attention on the role of sensors operating at microwave wavelengths as complementary tools for the real time estimations of source parameters. Microwaves can benefit of the operability during night and day and a relatively negligible sensitivity to the presence of clouds (non precipitating weather clouds) at the cost of a limited coverage and larger spatial resolution when compared with infrared sensors. Thanks to the aforementioned advantages, the products from microwaves sensors are expected to be sensible mostly to the whole path traversed along the tephra cloud making microwaves particularly

Effect of phase and orbital wave parameter choices on CS and IOS degeneracy averaged differential cross sections

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

Khare, V.; Fitz, D.E.; Kouri, D.J.

1980-09-15

The effect of phase choice and partial wave parameter choice on CS and IOS inelastic degeneracy averaged differential cross sections is studied. An approximate simplified CS scattering amplitude for l-bar=1/2(l'+l) is derived and is shown to have a form which closely resembles the McGuire--Kouri scattering amplitude for odd ..delta..j transitions and reduces to it for even ..delta..j transitions. The choice of phase in the CS wave function is shown to result in different approximations which yield significantly different shapes for the degeneracy averaged differential cross section. Time reversal symmetry arguments are employed to select the proper phase choice. IOS calculationsmore » of the degeneracy averaged differential cross sections of He--CO, He--Cl and Ne--HD using l-bar=1/2(l+l') and the phase choice which ensures proper time reversal symmetry are found to correct the phase disagreement which was previously noted for odd ..delta..j transitions using l-bar=l or l' and either the time reversal phase or other phase choices.« less

A Posteriori Error Analysis and Uncertainty Quantification for Adaptive Multiscale Operator Decomposition Methods for Multiphysics Problems

DTIC Science & Technology

2014-04-01

Barrier methods for critical exponent problems in geometric analysis and mathematical physics, J. Erway and M. Holst, Submitted for publication ...TR-14-33 A Posteriori Error Analysis and Uncertainty Quantification for Adaptive Multiscale Operator Decomposition Methods for Multiphysics...Problems Approved for public release, distribution is unlimited. April 2014 HDTRA1-09-1-0036 Donald Estep and Michael

A posteriori error estimation for multi-stage Runge–Kutta IMEX schemes

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

Chaudhry, Jehanzeb H.; Collins, J. B.; Shadid, John N.

Implicit–Explicit (IMEX) schemes are widely used for time integration methods for approximating solutions to a large class of problems. In this work, we develop accurate a posteriori error estimates of a quantity-of-interest for approximations obtained from multi-stage IMEX schemes. This is done by first defining a finite element method that is nodally equivalent to an IMEX scheme, then using typical methods for adjoint-based error estimation. Furthermore, the use of a nodally equivalent finite element method allows a decomposition of the error into multiple components, each describing the effect of a different portion of the method on the total error inmore » a quantity-of-interest.« less

A posteriori error estimation for multi-stage Runge–Kutta IMEX schemes

DOE PAGES

Chaudhry, Jehanzeb H.; Collins, J. B.; Shadid, John N.

2017-02-05

Implicit–Explicit (IMEX) schemes are widely used for time integration methods for approximating solutions to a large class of problems. In this work, we develop accurate a posteriori error estimates of a quantity-of-interest for approximations obtained from multi-stage IMEX schemes. This is done by first defining a finite element method that is nodally equivalent to an IMEX scheme, then using typical methods for adjoint-based error estimation. Furthermore, the use of a nodally equivalent finite element method allows a decomposition of the error into multiple components, each describing the effect of a different portion of the method on the total error inmore » a quantity-of-interest.« less

A LSQR-type method provides a computationally efficient automated optimal choice of regularization parameter in diffuse optical tomography.

PubMed

Prakash, Jaya; Yalavarthy, Phaneendra K

2013-03-01

Developing a computationally efficient automated method for the optimal choice of regularization parameter in diffuse optical tomography. The least-squares QR (LSQR)-type method that uses Lanczos bidiagonalization is known to be computationally efficient in performing the reconstruction procedure in diffuse optical tomography. The same is effectively deployed via an optimization procedure that uses the simplex method to find the optimal regularization parameter. The proposed LSQR-type method is compared with the traditional methods such as L-curve, generalized cross-validation (GCV), and recently proposed minimal residual method (MRM)-based choice of regularization parameter using numerical and experimental phantom data. The results indicate that the proposed LSQR-type and MRM-based methods performance in terms of reconstructed image quality is similar and superior compared to L-curve and GCV-based methods. The proposed method computational complexity is at least five times lower compared to MRM-based method, making it an optimal technique. The LSQR-type method was able to overcome the inherent limitation of computationally expensive nature of MRM-based automated way finding the optimal regularization parameter in diffuse optical tomographic imaging, making this method more suitable to be deployed in real-time.

A Novel A Posteriori Investigation of Scalar Flux Models for Passive Scalar Dispersion in Compressible Boundary Layer Flows

NASA Astrophysics Data System (ADS)

Braman, Kalen; Raman, Venkat

2011-11-01

A novel direct numerical simulation (DNS) based a posteriori technique has been developed to investigate scalar transport modeling error. The methodology is used to test Reynolds-averaged Navier-Stokes turbulent scalar flux models for compressible boundary layer flows. Time-averaged DNS velocity and turbulence fields provide the information necessary to evolve the time-averaged scalar transport equation without requiring the use of turbulence modeling. With this technique, passive dispersion of a scalar from a boundary layer surface in a supersonic flow is studied with scalar flux modeling error isolated from any flowfield modeling errors. Several different scalar flux models are used. It is seen that the simple gradient diffusion model overpredicts scalar dispersion, while anisotropic scalar flux models underpredict dispersion. Further, the use of more complex models does not necessarily guarantee an increase in predictive accuracy, indicating that key physics is missing from existing models. Using comparisons of both a priori and a posteriori scalar flux evaluations with DNS data, the main modeling shortcomings are identified. Results will be presented for different boundary layer conditions.

Determination of quantitative trait variants by concordance via application of the a posteriori granddaughter design to the U.S. Holstein population

USDA-ARS?s Scientific Manuscript database

Experimental designs that exploit family information can provide substantial predictive power in quantitative trait variant discovery projects. Concordance between quantitative trait locus genotype as determined by the a posteriori granddaughter design and marker genotype was determined for 29 trai...

Population pharmacokinetics and maximum a posteriori probability Bayesian estimator of abacavir: application of individualized therapy in HIV-infected infants and toddlers

PubMed Central

Zhao, Wei; Cella, Massimo; Della Pasqua, Oscar; Burger, David; Jacqz-Aigrain, Evelyne

2012-01-01

AIMS To develop a population pharmacokinetic model for abacavir in HIV-infected infants and toddlers, which will be used to describe both once and twice daily pharmacokinetic profiles, identify covariates that explain variability and propose optimal time points to optimize the area under the concentration–time curve (AUC) targeted dosage and individualize therapy. METHODS The pharmacokinetics of abacavir was described with plasma concentrations from 23 patients using nonlinear mixed-effects modelling (NONMEM) software. A two-compartment model with first-order absorption and elimination was developed. The final model was validated using bootstrap, visual predictive check and normalized prediction distribution errors. The Bayesian estimator was validated using the cross-validation and simulation–estimation method. RESULTS The typical population pharmacokinetic parameters and relative standard errors (RSE) were apparent systemic clearance (CL) 13.4 l h−1 (RSE 6.3%), apparent central volume of distribution 4.94 l (RSE 28.7%), apparent peripheral volume of distribution 8.12 l (RSE14.2%), apparent intercompartment clearance 1.25 l h−1 (RSE 16.9%) and absorption rate constant 0.758 h−1 (RSE 5.8%). The covariate analysis identified weight as the individual factor influencing the apparent oral clearance: CL = 13.4 × (weight/12)1.14. The maximum a posteriori probability Bayesian estimator, based on three concentrations measured at 0, 1 or 2, and 3 h after drug intake allowed predicting individual AUC0–t. CONCLUSIONS The population pharmacokinetic model developed for abacavir in HIV-infected infants and toddlers accurately described both once and twice daily pharmacokinetic profiles. The maximum a posteriori probability Bayesian estimator of AUC0–t was developed from the final model and can be used routinely to optimize individual dosing. PMID:21988586

The Impact of Escape Alternative Position Change in Multiple-Choice Test on the Psychometric Properties of a Test and Its Items Parameters

ERIC Educational Resources Information Center

Hamadneh, Iyad Mohammed

2015-01-01

This study aimed at investigating the impact changing of escape alternative position in multiple-choice test on the psychometric properties of a test and it's items parameters (difficulty, discrimination & guessing), and estimation of examinee ability. To achieve the study objectives, a 4-alternative multiple choice type achievement test…

Sparsity-promoting and edge-preserving maximum a posteriori estimators in non-parametric Bayesian inverse problems

NASA Astrophysics Data System (ADS)

Agapiou, Sergios; Burger, Martin; Dashti, Masoumeh; Helin, Tapio

2018-04-01

We consider the inverse problem of recovering an unknown functional parameter u in a separable Banach space, from a noisy observation vector y of its image through a known possibly non-linear map {{\\mathcal G}} . We adopt a Bayesian approach to the problem and consider Besov space priors (see Lassas et al (2009 Inverse Problems Imaging 3 87-122)), which are well-known for their edge-preserving and sparsity-promoting properties and have recently attracted wide attention especially in the medical imaging community. Our key result is to show that in this non-parametric setup the maximum a posteriori (MAP) estimates are characterized by the minimizers of a generalized Onsager-Machlup functional of the posterior. This is done independently for the so-called weak and strong MAP estimates, which as we show coincide in our context. In addition, we prove a form of weak consistency for the MAP estimators in the infinitely informative data limit. Our results are remarkable for two reasons: first, the prior distribution is non-Gaussian and does not meet the smoothness conditions required in previous research on non-parametric MAP estimates. Second, the result analytically justifies existing uses of the MAP estimate in finite but high dimensional discretizations of Bayesian inverse problems with the considered Besov priors.

Variance Difference between Maximum Likelihood Estimation Method and Expected A Posteriori Estimation Method Viewed from Number of Test Items

ERIC Educational Resources Information Center

Mahmud, Jumailiyah; Sutikno, Muzayanah; Naga, Dali S.

2016-01-01

The aim of this study is to determine variance difference between maximum likelihood and expected A posteriori estimation methods viewed from number of test items of aptitude test. The variance presents an accuracy generated by both maximum likelihood and Bayes estimation methods. The test consists of three subtests, each with 40 multiple-choice…

Population pharmacokinetics and maximum a posteriori probability Bayesian estimator of abacavir: application of individualized therapy in HIV-infected infants and toddlers.

PubMed

Zhao, Wei; Cella, Massimo; Della Pasqua, Oscar; Burger, David; Jacqz-Aigrain, Evelyne

2012-04-01

Abacavir is used to treat HIV infection in both adults and children. The recommended paediatric dose is 8 mg kg(-1) twice daily up to a maximum of 300 mg twice daily. Weight was identified as the central covariate influencing pharmacokinetics of abacavir in children. A population pharmacokinetic model was developed to describe both once and twice daily pharmacokinetic profiles of abacavir in infants and toddlers. Standard dosage regimen is associated with large interindividual variability in abacavir concentrations. A maximum a posteriori probability Bayesian estimator of AUC(0-) (t) based on three time points (0, 1 or 2, and 3 h) is proposed to support area under the concentration-time curve (AUC) targeted individualized therapy in infants and toddlers. To develop a population pharmacokinetic model for abacavir in HIV-infected infants and toddlers, which will be used to describe both once and twice daily pharmacokinetic profiles, identify covariates that explain variability and propose optimal time points to optimize the area under the concentration-time curve (AUC) targeted dosage and individualize therapy. The pharmacokinetics of abacavir was described with plasma concentrations from 23 patients using nonlinear mixed-effects modelling (NONMEM) software. A two-compartment model with first-order absorption and elimination was developed. The final model was validated using bootstrap, visual predictive check and normalized prediction distribution errors. The Bayesian estimator was validated using the cross-validation and simulation-estimation method. The typical population pharmacokinetic parameters and relative standard errors (RSE) were apparent systemic clearance (CL) 13.4 () h−1 (RSE 6.3%), apparent central volume of distribution 4.94 () (RSE 28.7%), apparent peripheral volume of distribution 8.12 () (RSE14.2%), apparent intercompartment clearance 1.25 () h−1 (RSE 16.9%) and absorption rate constant 0.758 h−1 (RSE 5.8%). The covariate analysis

Choice-Based Conjoint Analysis: Classification vs. Discrete Choice Models

NASA Astrophysics Data System (ADS)

Giesen, Joachim; Mueller, Klaus; Taneva, Bilyana; Zolliker, Peter

Conjoint analysis is a family of techniques that originated in psychology and later became popular in market research. The main objective of conjoint analysis is to measure an individual's or a population's preferences on a class of options that can be described by parameters and their levels. We consider preference data obtained in choice-based conjoint analysis studies, where one observes test persons' choices on small subsets of the options. There are many ways to analyze choice-based conjoint analysis data. Here we discuss the intuition behind a classification based approach, and compare this approach to one based on statistical assumptions (discrete choice models) and to a regression approach. Our comparison on real and synthetic data indicates that the classification approach outperforms the discrete choice models.

A-posteriori error estimation for the finite point method with applications to compressible flow

NASA Astrophysics Data System (ADS)

Ortega, Enrique; Flores, Roberto; Oñate, Eugenio; Idelsohn, Sergio

2017-08-01

An a-posteriori error estimate with application to inviscid compressible flow problems is presented. The estimate is a surrogate measure of the discretization error, obtained from an approximation to the truncation terms of the governing equations. This approximation is calculated from the discrete nodal differential residuals using a reconstructed solution field on a modified stencil of points. Both the error estimation methodology and the flow solution scheme are implemented using the Finite Point Method, a meshless technique enabling higher-order approximations and reconstruction procedures on general unstructured discretizations. The performance of the proposed error indicator is studied and applications to adaptive grid refinement are presented.

A Bayesian approach to tracking patients having changing pharmacokinetic parameters

NASA Technical Reports Server (NTRS)

Bayard, David S.; Jelliffe, Roger W.

2004-01-01

This paper considers the updating of Bayesian posterior densities for pharmacokinetic models associated with patients having changing parameter values. For estimation purposes it is proposed to use the Interacting Multiple Model (IMM) estimation algorithm, which is currently a popular algorithm in the aerospace community for tracking maneuvering targets. The IMM algorithm is described, and compared to the multiple model (MM) and Maximum A-Posteriori (MAP) Bayesian estimation methods, which are presently used for posterior updating when pharmacokinetic parameters do not change. Both the MM and MAP Bayesian estimation methods are used in their sequential forms, to facilitate tracking of changing parameters. Results indicate that the IMM algorithm is well suited for tracking time-varying pharmacokinetic parameters in acutely ill and unstable patients, incurring only about half of the integrated error compared to the sequential MM and MAP methods on the same example.

Multiobjective constraints for climate model parameter choices: Pragmatic Pareto fronts in CESM1

NASA Astrophysics Data System (ADS)

Langenbrunner, B.; Neelin, J. D.

2017-09-01

Global climate models (GCMs) are examples of high-dimensional input-output systems, where model output is a function of many variables, and an update in model physics commonly improves performance in one objective function (i.e., measure of model performance) at the expense of degrading another. Here concepts from multiobjective optimization in the engineering literature are used to investigate parameter sensitivity and optimization in the face of such trade-offs. A metamodeling technique called cut high-dimensional model representation (cut-HDMR) is leveraged in the context of multiobjective optimization to improve GCM simulation of the tropical Pacific climate, focusing on seasonal precipitation, column water vapor, and skin temperature. An evolutionary algorithm is used to solve for Pareto fronts, which are surfaces in objective function space along which trade-offs in GCM performance occur. This approach allows the modeler to visualize trade-offs quickly and identify the physics at play. In some cases, Pareto fronts are small, implying that trade-offs are minimal, optimal parameter value choices are more straightforward, and the GCM is well-functioning. In all cases considered here, the control run was found not to be Pareto-optimal (i.e., not on the front), highlighting an opportunity for model improvement through objectively informed parameter selection. Taylor diagrams illustrate that these improvements occur primarily in field magnitude, not spatial correlation, and they show that specific parameter updates can improve fields fundamental to tropical moist processes—namely precipitation and skin temperature—without significantly impacting others. These results provide an example of how basic elements of multiobjective optimization can facilitate pragmatic GCM tuning processes.

Modeling the dynamics of choice.

PubMed

Baum, William M; Davison, Michael

2009-06-01

A simple linear-operator model both describes and predicts the dynamics of choice that may underlie the matching relation. We measured inter-food choice within components of a schedule that presented seven different pairs of concurrent variable-interval schedules for 12 food deliveries each with no signals indicating which pair was in force. This measure of local choice was accurately described and predicted as obtained reinforcer sequences shifted it to favor one alternative or the other. The effect of a changeover delay was reflected in one parameter, the asymptote, whereas the effect of a difference in overall rate of food delivery was reflected in the other parameter, rate of approach to the asymptote. The model takes choice as a primary dependent variable, not derived by comparison between alternatives-an approach that agrees with the molar view of behaviour.

Using meta-information of a posteriori Bayesian solutions of the hypocentre location task for improving accuracy of location error estimation

NASA Astrophysics Data System (ADS)

Debski, Wojciech

2015-06-01

The spatial location of sources of seismic waves is one of the first tasks when transient waves from natural (uncontrolled) sources are analysed in many branches of physics, including seismology, oceanology, to name a few. Source activity and its spatial variability in time, the geometry of recording network, the complexity and heterogeneity of wave velocity distribution are all factors influencing the performance of location algorithms and accuracy of the achieved results. Although estimating of the earthquake foci location is relatively simple, a quantitative estimation of the location accuracy is really a challenging task even if the probabilistic inverse method is used because it requires knowledge of statistics of observational, modelling and a priori uncertainties. In this paper, we addressed this task when statistics of observational and/or modelling errors are unknown. This common situation requires introduction of a priori constraints on the likelihood (misfit) function which significantly influence the estimated errors. Based on the results of an analysis of 120 seismic events from the Rudna copper mine operating in southwestern Poland, we propose an approach based on an analysis of Shanon's entropy calculated for the a posteriori distribution. We show that this meta-characteristic of the a posteriori distribution carries some information on uncertainties of the solution found.

Simultaneous maximum a posteriori longitudinal PET image reconstruction

NASA Astrophysics Data System (ADS)

Ellis, Sam; Reader, Andrew J.

2017-09-01

Positron emission tomography (PET) is frequently used to monitor functional changes that occur over extended time scales, for example in longitudinal oncology PET protocols that include routine clinical follow-up scans to assess the efficacy of a course of treatment. In these contexts PET datasets are currently reconstructed into images using single-dataset reconstruction methods. Inspired by recently proposed joint PET-MR reconstruction methods, we propose to reconstruct longitudinal datasets simultaneously by using a joint penalty term in order to exploit the high degree of similarity between longitudinal images. We achieved this by penalising voxel-wise differences between pairs of longitudinal PET images in a one-step-late maximum a posteriori (MAP) fashion, resulting in the MAP simultaneous longitudinal reconstruction (SLR) method. The proposed method reduced reconstruction errors and visually improved images relative to standard maximum likelihood expectation-maximisation (ML-EM) in simulated 2D longitudinal brain tumour scans. In reconstructions of split real 3D data with inserted simulated tumours, noise across images reconstructed with MAP-SLR was reduced to levels equivalent to doubling the number of detected counts when using ML-EM. Furthermore, quantification of tumour activities was largely preserved over a variety of longitudinal tumour changes, including changes in size and activity, with larger changes inducing larger biases relative to standard ML-EM reconstructions. Similar improvements were observed for a range of counts levels, demonstrating the robustness of the method when used with a single penalty strength. The results suggest that longitudinal regularisation is a simple but effective method of improving reconstructed PET images without using resolution degrading priors.

Person authentication using brainwaves (EEG) and maximum a posteriori model adaptation.

PubMed

Marcel, Sébastien; Millán, José Del R

2007-04-01

In this paper, we investigate the use of brain activity for person authentication. It has been shown in previous studies that the brain-wave pattern of every individual is unique and that the electroencephalogram (EEG) can be used for biometric identification. EEG-based biometry is an emerging research topic and we believe that it may open new research directions and applications in the future. However, very little work has been done in this area and was focusing mainly on person identification but not on person authentication. Person authentication aims to accept or to reject a person claiming an identity, i.e., comparing a biometric data to one template, while the goal of person identification is to match the biometric data against all the records in a database. We propose the use of a statistical framework based on Gaussian Mixture Models and Maximum A Posteriori model adaptation, successfully applied to speaker and face authentication, which can deal with only one training session. We perform intensive experimental simulations using several strict train/test protocols to show the potential of our method. We also show that there are some mental tasks that are more appropriate for person authentication than others.

A new anisotropic mesh adaptation method based upon hierarchical a posteriori error estimates

NASA Astrophysics Data System (ADS)

Huang, Weizhang; Kamenski, Lennard; Lang, Jens

2010-03-01

A new anisotropic mesh adaptation strategy for finite element solution of elliptic differential equations is presented. It generates anisotropic adaptive meshes as quasi-uniform ones in some metric space, with the metric tensor being computed based on hierarchical a posteriori error estimates. A global hierarchical error estimate is employed in this study to obtain reliable directional information of the solution. Instead of solving the global error problem exactly, which is costly in general, we solve it iteratively using the symmetric Gauß-Seidel method. Numerical results show that a few GS iterations are sufficient for obtaining a reasonably good approximation to the error for use in anisotropic mesh adaptation. The new method is compared with several strategies using local error estimators or recovered Hessians. Numerical results are presented for a selection of test examples and a mathematical model for heat conduction in a thermal battery with large orthotropic jumps in the material coefficients.

Reconstruction of signals with unknown spectra in information field theory with parameter uncertainty

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

Ensslin, Torsten A.; Frommert, Mona

2011-05-15

The optimal reconstruction of cosmic metric perturbations and other signals requires knowledge of their power spectra and other parameters. If these are not known a priori, they have to be measured simultaneously from the same data used for the signal reconstruction. We formulate the general problem of signal inference in the presence of unknown parameters within the framework of information field theory. To solve this, we develop a generic parameter-uncertainty renormalized estimation (PURE) technique. As a concrete application, we address the problem of reconstructing Gaussian signals with unknown power-spectrum with five different approaches: (i) separate maximum-a-posteriori power-spectrum measurement and subsequentmore » reconstruction, (ii) maximum-a-posteriori reconstruction with marginalized power-spectrum, (iii) maximizing the joint posterior of signal and spectrum, (iv) guessing the spectrum from the variance in the Wiener-filter map, and (v) renormalization flow analysis of the field-theoretical problem providing the PURE filter. In all cases, the reconstruction can be described or approximated as Wiener-filter operations with assumed signal spectra derived from the data according to the same recipe, but with differing coefficients. All of these filters, except the renormalized one, exhibit a perception threshold in case of a Jeffreys prior for the unknown spectrum. Data modes with variance below this threshold do not affect the signal reconstruction at all. Filter (iv) seems to be similar to the so-called Karhune-Loeve and Feldman-Kaiser-Peacock estimators for galaxy power spectra used in cosmology, which therefore should also exhibit a marginal perception threshold if correctly implemented. We present statistical performance tests and show that the PURE filter is superior to the others, especially if the post-Wiener-filter corrections are included or in case an additional scale-independent spectral smoothness prior can be adopted.« less

Automatic lung lobe segmentation using particles, thin plate splines, and maximum a posteriori estimation.

PubMed

Ross, James C; San José Estépar, Rail; Kindlmann, Gordon; Díaz, Alejandro; Westin, Carl-Fredrik; Silverman, Edwin K; Washko, George R

2010-01-01

We present a fully automatic lung lobe segmentation algorithm that is effective in high resolution computed tomography (CT) datasets in the presence of confounding factors such as incomplete fissures (anatomical structures indicating lobe boundaries), advanced disease states, high body mass index (BMI), and low-dose scanning protocols. In contrast to other algorithms that leverage segmentations of auxiliary structures (esp. vessels and airways), we rely only upon image features indicating fissure locations. We employ a particle system that samples the image domain and provides a set of candidate fissure locations. We follow this stage with maximum a posteriori (MAP) estimation to eliminate poor candidates and then perform a post-processing operation to remove remaining noise particles. We then fit a thin plate spline (TPS) interpolating surface to the fissure particles to form the final lung lobe segmentation. Results indicate that our algorithm performs comparably to pulmonologist-generated lung lobe segmentations on a set of challenging cases.

Automatic Lung Lobe Segmentation Using Particles, Thin Plate Splines, and Maximum a Posteriori Estimation

PubMed Central

Ross, James C.; Estépar, Raúl San José; Kindlmann, Gordon; Díaz, Alejandro; Westin, Carl-Fredrik; Silverman, Edwin K.; Washko, George R.

2011-01-01

We present a fully automatic lung lobe segmentation algorithm that is effective in high resolution computed tomography (CT) datasets in the presence of confounding factors such as incomplete fissures (anatomical structures indicating lobe boundaries), advanced disease states, high body mass index (BMI), and low-dose scanning protocols. In contrast to other algorithms that leverage segmentations of auxiliary structures (esp. vessels and airways), we rely only upon image features indicating fissure locations. We employ a particle system that samples the image domain and provides a set of candidate fissure locations. We follow this stage with maximum a posteriori (MAP) estimation to eliminate poor candidates and then perform a post-processing operation to remove remaining noise particles. We then fit a thin plate spline (TPS) interpolating surface to the fissure particles to form the final lung lobe segmentation. Results indicate that our algorithm performs comparably to pulmonologist-generated lung lobe segmentations on a set of challenging cases. PMID:20879396

A priori and a posteriori analysis of the flow around a rectangular cylinder

NASA Astrophysics Data System (ADS)

Cimarelli, A.; Leonforte, A.; Franciolini, M.; De Angelis, E.; Angeli, D.; Crivellini, A.

2017-11-01

The definition of a correct mesh resolution and modelling approach for the Large Eddy Simulation (LES) of the flow around a rectangular cylinder is recognized to be a rather elusive problem as shown by the large scatter of LES results present in the literature. In the present work, we aim at assessing this issue by performing an a priori analysis of Direct Numerical Simulation (DNS) data of the flow. This approach allows us to measure the ability of the LES field on reproducing the main flow features as a function of the resolution employed. Based on these results, we define a mesh resolution which maximize the opposite needs of reducing the computational costs and of adequately resolving the flow dynamics. The effectiveness of the resolution method proposed is then verified by means of an a posteriori analysis of actual LES data obtained by means of the implicit LES approach given by the numerical properties of the Discontinuous Galerkin spatial discretization technique. The present work represents a first step towards a best practice for LES of separating and reattaching flows.

Preconditioned alternating projection algorithms for maximum a posteriori ECT reconstruction

NASA Astrophysics Data System (ADS)

Krol, Andrzej; Li, Si; Shen, Lixin; Xu, Yuesheng

2012-11-01

We propose a preconditioned alternating projection algorithm (PAPA) for solving the maximum a posteriori (MAP) emission computed tomography (ECT) reconstruction problem. Specifically, we formulate the reconstruction problem as a constrained convex optimization problem with the total variation (TV) regularization. We then characterize the solution of the constrained convex optimization problem and show that it satisfies a system of fixed-point equations defined in terms of two proximity operators raised from the convex functions that define the TV-norm and the constraint involved in the problem. The characterization (of the solution) via the proximity operators that define two projection operators naturally leads to an alternating projection algorithm for finding the solution. For efficient numerical computation, we introduce to the alternating projection algorithm a preconditioning matrix (the EM-preconditioner) for the dense system matrix involved in the optimization problem. We prove theoretically convergence of the PAPA. In numerical experiments, performance of our algorithms, with an appropriately selected preconditioning matrix, is compared with performance of the conventional MAP expectation-maximization (MAP-EM) algorithm with TV regularizer (EM-TV) and that of the recently developed nested EM-TV algorithm for ECT reconstruction. Based on the numerical experiments performed in this work, we observe that the alternating projection algorithm with the EM-preconditioner outperforms significantly the EM-TV in all aspects including the convergence speed, the noise in the reconstructed images and the image quality. It also outperforms the nested EM-TV in the convergence speed while providing comparable image quality.

An evolutionary firefly algorithm for the estimation of nonlinear biological model parameters.

PubMed

Abdullah, Afnizanfaizal; Deris, Safaai; Anwar, Sohail; Arjunan, Satya N V

2013-01-01

The development of accurate computational models of biological processes is fundamental to computational systems biology. These models are usually represented by mathematical expressions that rely heavily on the system parameters. The measurement of these parameters is often difficult. Therefore, they are commonly estimated by fitting the predicted model to the experimental data using optimization methods. The complexity and nonlinearity of the biological processes pose a significant challenge, however, to the development of accurate and fast optimization methods. We introduce a new hybrid optimization method incorporating the Firefly Algorithm and the evolutionary operation of the Differential Evolution method. The proposed method improves solutions by neighbourhood search using evolutionary procedures. Testing our method on models for the arginine catabolism and the negative feedback loop of the p53 signalling pathway, we found that it estimated the parameters with high accuracy and within a reasonable computation time compared to well-known approaches, including Particle Swarm Optimization, Nelder-Mead, and Firefly Algorithm. We have also verified the reliability of the parameters estimated by the method using an a posteriori practical identifiability test.

An Evolutionary Firefly Algorithm for the Estimation of Nonlinear Biological Model Parameters

PubMed Central

Abdullah, Afnizanfaizal; Deris, Safaai; Anwar, Sohail; Arjunan, Satya N. V.

2013-01-01

The development of accurate computational models of biological processes is fundamental to computational systems biology. These models are usually represented by mathematical expressions that rely heavily on the system parameters. The measurement of these parameters is often difficult. Therefore, they are commonly estimated by fitting the predicted model to the experimental data using optimization methods. The complexity and nonlinearity of the biological processes pose a significant challenge, however, to the development of accurate and fast optimization methods. We introduce a new hybrid optimization method incorporating the Firefly Algorithm and the evolutionary operation of the Differential Evolution method. The proposed method improves solutions by neighbourhood search using evolutionary procedures. Testing our method on models for the arginine catabolism and the negative feedback loop of the p53 signalling pathway, we found that it estimated the parameters with high accuracy and within a reasonable computation time compared to well-known approaches, including Particle Swarm Optimization, Nelder-Mead, and Firefly Algorithm. We have also verified the reliability of the parameters estimated by the method using an a posteriori practical identifiability test. PMID:23469172

Preconditioned Alternating Projection Algorithms for Maximum a Posteriori ECT Reconstruction

PubMed Central

Krol, Andrzej; Li, Si; Shen, Lixin; Xu, Yuesheng

2012-01-01

We propose a preconditioned alternating projection algorithm (PAPA) for solving the maximum a posteriori (MAP) emission computed tomography (ECT) reconstruction problem. Specifically, we formulate the reconstruction problem as a constrained convex optimization problem with the total variation (TV) regularization. We then characterize the solution of the constrained convex optimization problem and show that it satisfies a system of fixed-point equations defined in terms of two proximity operators raised from the convex functions that define the TV-norm and the constrain involved in the problem. The characterization (of the solution) via the proximity operators that define two projection operators naturally leads to an alternating projection algorithm for finding the solution. For efficient numerical computation, we introduce to the alternating projection algorithm a preconditioning matrix (the EM-preconditioner) for the dense system matrix involved in the optimization problem. We prove theoretically convergence of the preconditioned alternating projection algorithm. In numerical experiments, performance of our algorithms, with an appropriately selected preconditioning matrix, is compared with performance of the conventional MAP expectation-maximization (MAP-EM) algorithm with TV regularizer (EM-TV) and that of the recently developed nested EM-TV algorithm for ECT reconstruction. Based on the numerical experiments performed in this work, we observe that the alternating projection algorithm with the EM-preconditioner outperforms significantly the EM-TV in all aspects including the convergence speed, the noise in the reconstructed images and the image quality. It also outperforms the nested EM-TV in the convergence speed while providing comparable image quality. PMID:23271835

The assessment of body sway and the choice of the stability parameter(s).

PubMed

Raymakers, J A; Samson, M M; Verhaar, H J J

2005-01-01

This methodological study aims at comparison of the practical usefulness of several parameters of body sway derived from recordings of the center of pressure (CoP) with the aid of a static force platform as proposed in the literature. These included: mean displacement velocity, maximal range of movement along x- and y-co-ordinates, movement area, planar deviation, phase plane parameter of Riley and the parameters of the diffusion stabilogram according to Collins. They were compared in over 850 experiments in a group of young healthy subjects (n = 10, age 21-45 years), a group of elderly healthy (n = 38, age 61-78 years) and two groups of elderly subjects (n = 10 and n = 21, age 65-89 years) with stability problems under different conditions known to interfere with stability as compared to standing with open eyes fixing a visual anchoring point: closing the eyes, standing on plastic foam in stead of a firm surface and performing a cognitive task: the modified stroop test. A force platform (Kistler) was used and co-ordinates of the body's center of pressure were recorded during 60 s of quiet barefoot standing with a sampling frequency of 10 Hz. In general, the results show important overlapping among groups and test conditions. Mean displacement velocity shows the most consistent differences between test situations, health conditions and age ranges, but is not affected by an extra cognitive task in healthy old people. Mean maximal sideways sway range is different among groups and test conditions except for the cognitive task in young and elderly subjects. Standardised displacement parameters such as standard deviations of displacements and planar deviation discriminate less well than the actual range of motion or the velocity. The critical time interval derived from the diffusion stabilogram according to Collins et al. seems to add a specific type of information since it shows significant influence from addition of a cognitive task in old subjects standing on a firm

Does Correct Answer Distribution Influence Student Choices When Writing Multiple Choice Examinations?

ERIC Educational Resources Information Center

Carnegie, Jacqueline A.

2017-01-01

Summative evaluation for large classes of first- and second-year undergraduate courses often involves the use of multiple choice question (MCQ) exams in order to provide timely feedback. Several versions of those exams are often prepared via computer-based question scrambling in an effort to deter cheating. An important parameter to consider when…

Exclusive queueing model including the choice of service windows

NASA Astrophysics Data System (ADS)

Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

2018-01-01

In a queueing system involving multiple service windows, choice behavior is a significant concern. This paper incorporates the choice of service windows into a queueing model with a floor represented by discrete cells. We contrived a logit-based choice algorithm for agents considering the numbers of agents and the distances to all service windows. Simulations were conducted with various parameters of agent choice preference for these two elements and for different floor configurations, including the floor length and the number of service windows. We investigated the model from the viewpoint of transit times and entrance block rates. The influences of the parameters on these factors were surveyed in detail and we determined that there are optimum floor lengths that minimize the transit times. In addition, we observed that the transit times were determined almost entirely by the entrance block rates. The results of the presented model are relevant to understanding queueing systems including the choice of service windows and can be employed to optimize facility design and floor management.

Prospect theory based estimation of drivers' risk attitudes in route choice behaviors.

PubMed

Zhou, Lizhen; Zhong, Shiquan; Ma, Shoufeng; Jia, Ning

2014-12-01

This paper applied prospect theory (PT) to describe drivers' route choice behavior under Variable Message Sign (VMS), which presented visual traffic information to assist them to make route choice decisions. A quite rich empirical data from questionnaire and field spot was used to estimate parameters of PT. In order to make the parameters more realistic with drivers' attitudes, they were classified into different types by significant factors influencing their behaviors. Based on the travel time distribution of alternative routes and route choice results from questionnaire, the parameterized value function of each category was figured out, which represented drivers' risk attitudes and choice characteristics. The empirical verification showed that the estimates were acceptable and effective. The result showed drivers' risk attitudes and route choice characteristics could be captured by PT under real-time information shown on VMS. For practical application, once drivers' route choice characteristics and parameters were identified, their route choice behavior under different road conditions could be predicted accurately, which was the basis of traffic guidance measures formulation and implementation for targeted traffic management. Moreover, the heterogeneous risk attitudes among drivers should be considered when releasing traffic information and regulating traffic flow. Copyright © 2014 Elsevier Ltd. All rights reserved.

A PREFERENCE-OPPORTUNITY-CHOICE FRAMEWORK WITH APPLICATIONS TO INTERGROUP FRIENDSHIP*

PubMed Central

Zeng, Zhen; Xie, Yu

2009-01-01

A longstanding objective of friendship research is to identify the effects of personal preference and structural opportunity on intergroup friendship choice. Although past studies have used various methods to separate preference from opportunity, researchers have not yet systematically compared the properties and implications of these methods. We put forward a general framework for discrete choice, where choice probability is specified as proportional to the product of preference and opportunity. To implement this framework, we propose a modification to the conditional logit model for estimating preference parameters free from the influence of opportunity structure. We then compare our approach to several alternative methods for separating preference and opportunity used in the friendship choice literature. As an empirical example, we test hypotheses of homophily and status asymmetry in friendship choice using data from the National Longitudinal Study of Adolescent Health. The example also demonstrates the approach of conducting a sensitivity analysis to examine how parameter estimates vary by specification of the opportunity structure. PMID:19569394

Reliable and efficient a posteriori error estimation for adaptive IGA boundary element methods for weakly-singular integral equations

PubMed Central

Feischl, Michael; Gantner, Gregor; Praetorius, Dirk

2015-01-01

We consider the Galerkin boundary element method (BEM) for weakly-singular integral equations of the first-kind in 2D. We analyze some residual-type a posteriori error estimator which provides a lower as well as an upper bound for the unknown Galerkin BEM error. The required assumptions are weak and allow for piecewise smooth parametrizations of the boundary, local mesh-refinement, and related standard piecewise polynomials as well as NURBS. In particular, our analysis gives a first contribution to adaptive BEM in the frame of isogeometric analysis (IGABEM), for which we formulate an adaptive algorithm which steers the local mesh-refinement and the multiplicity of the knots. Numerical experiments underline the theoretical findings and show that the proposed adaptive strategy leads to optimal convergence. PMID:26085698

Level set segmentation of medical images based on local region statistics and maximum a posteriori probability.

PubMed

Cui, Wenchao; Wang, Yi; Lei, Tao; Fan, Yangyu; Feng, Yan

2013-01-01

This paper presents a variational level set method for simultaneous segmentation and bias field estimation of medical images with intensity inhomogeneity. In our model, the statistics of image intensities belonging to each different tissue in local regions are characterized by Gaussian distributions with different means and variances. According to maximum a posteriori probability (MAP) and Bayes' rule, we first derive a local objective function for image intensities in a neighborhood around each pixel. Then this local objective function is integrated with respect to the neighborhood center over the entire image domain to give a global criterion. In level set framework, this global criterion defines an energy in terms of the level set functions that represent a partition of the image domain and a bias field that accounts for the intensity inhomogeneity of the image. Therefore, image segmentation and bias field estimation are simultaneously achieved via a level set evolution process. Experimental results for synthetic and real images show desirable performances of our method.

Factors that influence beverage choices at meal times. An application of the food choice kaleidoscope framework.

PubMed

Mueller Loose, S; Jaeger, S R

2012-12-01

Beverages are consumed at almost every meal occasion, but knowledge about the factors that influence beverage choice is less than for food choice. The aim of this research was to characterize and quantify factors that influence beverage choices at meal times. Insights into what beverages are chosen by whom, when and where can be helpful for manufacturers, dieticians/health care providers, and health policy makers. A descriptive framework - the food choice kaleidoscope (Jaeger et al., 2011) - was applied to self-reported 24h food recall data from a sample of New Zealand consumers. Participants (n=164) described 8356 meal occasions in terms of foods and beverages consumed, and the contextual characteristics of the occasion. Beverage choice was explored with random-parameter logit regressions to reveal influences linked to food items eaten, context factors and person factors. Thereby this study contributed to the food choice kaleidoscope research approach by expressing the degree of context dependency in the form of odds ratios and according significance levels. The exploration of co-occurrence of beverages with food items suggests that beverage-meal item combinations can be meal specific. Furthermore, this study integrates psychographic variables into the 'person' mirror of the food choice kaleidoscope. A measure of habit in beverage choice was obtained from the inter-participant correlation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Research on adaptive optics image restoration algorithm based on improved joint maximum a posteriori method

NASA Astrophysics Data System (ADS)

Zhang, Lijuan; Li, Yang; Wang, Junnan; Liu, Ying

2018-03-01

In this paper, we propose a point spread function (PSF) reconstruction method and joint maximum a posteriori (JMAP) estimation method for the adaptive optics image restoration. Using the JMAP method as the basic principle, we establish the joint log likelihood function of multi-frame adaptive optics (AO) images based on the image Gaussian noise models. To begin with, combining the observed conditions and AO system characteristics, a predicted PSF model for the wavefront phase effect is developed; then, we build up iterative solution formulas of the AO image based on our proposed algorithm, addressing the implementation process of multi-frame AO images joint deconvolution method. We conduct a series of experiments on simulated and real degraded AO images to evaluate our proposed algorithm. Compared with the Wiener iterative blind deconvolution (Wiener-IBD) algorithm and Richardson-Lucy IBD algorithm, our algorithm has better restoration effects including higher peak signal-to-noise ratio ( PSNR) and Laplacian sum ( LS) value than the others. The research results have a certain application values for actual AO image restoration.

A Posteriori Study of a DNS Database Describing Super critical Binary-Species Mixing

NASA Technical Reports Server (NTRS)

Bellan, Josette; Taskinoglu, Ezgi

2012-01-01

Currently, the modeling of supercritical-pressure flows through Large Eddy Simulation (LES) uses models derived for atmospheric-pressure flows. Those atmospheric-pressure flows do not exhibit the particularities of high densitygradient magnitude features observed both in experiments and simulations of supercritical-pressure flows in the case of two species mixing. To assess whether the current LES modeling is appropriate and if found not appropriate to propose higher-fidelity models, a LES a posteriori study has been conducted for a mixing layer that initially contains different species in the lower and upper streams, and where the initial pressure is larger than the critical pressure of either species. An initially-imposed vorticity perturbation promotes roll-up and a double pairing of four initial span-wise vortices into an ultimate vortex that reaches a transitional state. The LES equations consist of the differential conservation equations coupled with a real-gas equation of state, and the equation set uses transport properties depending on the thermodynamic variables. Unlike all LES models to date, the differential equations contain, additional to the subgrid scale (SGS) fluxes, a new SGS term that is a pressure correction in the momentum equation. This additional term results from filtering of Direct Numerical Simulation (DNS) equations, and represents the gradient of the difference between the filtered pressure and the pressure computed from the filtered flow field. A previous a priori analysis, using a DNS database for the same configuration, found this term to be of leading order in the momentum equation, a fact traced to the existence of high-densitygradient magnitude regions that populated the entire flow; in the study, models were proposed for the SGS fluxes as well as this new term. In the present study, the previously proposed constantcoefficient SGS-flux models of the a priori investigation are tested a posteriori in LES, devoid of or including, the

An a-posteriori finite element error estimator for adaptive grid computation of viscous incompressible flows

NASA Astrophysics Data System (ADS)

Wu, Heng

2000-10-01

In this thesis, an a-posteriori error estimator is presented and employed for solving viscous incompressible flow problems. In an effort to detect local flow features, such as vortices and separation, and to resolve flow details precisely, a velocity angle error estimator e theta which is based on the spatial derivative of velocity direction fields is designed and constructed. The a-posteriori error estimator corresponds to the antisymmetric part of the deformation-rate-tensor, and it is sensitive to the second derivative of the velocity angle field. Rationality discussions reveal that the velocity angle error estimator is a curvature error estimator, and its value reflects the accuracy of streamline curves. It is also found that the velocity angle error estimator contains the nonlinear convective term of the Navier-Stokes equations, and it identifies and computes the direction difference when the convective acceleration direction and the flow velocity direction have a disparity. Through benchmarking computed variables with the analytic solution of Kovasznay flow or the finest grid of cavity flow, it is demonstrated that the velocity angle error estimator has a better performance than the strain error estimator. The benchmarking work also shows that the computed profile obtained by using etheta can achieve the best matching outcome with the true theta field, and that it is asymptotic to the true theta variation field, with a promise of fewer unknowns. Unstructured grids are adapted by employing local cell division as well as unrefinement of transition cells. Using element class and node class can efficiently construct a hierarchical data structure which provides cell and node inter-reference at each adaptive level. Employing element pointers and node pointers can dynamically maintain the connection of adjacent elements and adjacent nodes, and thus avoids time-consuming search processes. The adaptive scheme is applied to viscous incompressible flow at different

The drift diffusion model as the choice rule in reinforcement learning.

PubMed

Pedersen, Mads Lund; Frank, Michael J; Biele, Guido

2017-08-01

Current reinforcement-learning models often assume simplified decision processes that do not fully reflect the dynamic complexities of choice processes. Conversely, sequential-sampling models of decision making account for both choice accuracy and response time, but assume that decisions are based on static decision values. To combine these two computational models of decision making and learning, we implemented reinforcement-learning models in which the drift diffusion model describes the choice process, thereby capturing both within- and across-trial dynamics. To exemplify the utility of this approach, we quantitatively fit data from a common reinforcement-learning paradigm using hierarchical Bayesian parameter estimation, and compared model variants to determine whether they could capture the effects of stimulant medication in adult patients with attention-deficit hyperactivity disorder (ADHD). The model with the best relative fit provided a good description of the learning process, choices, and response times. A parameter recovery experiment showed that the hierarchical Bayesian modeling approach enabled accurate estimation of the model parameters. The model approach described here, using simultaneous estimation of reinforcement-learning and drift diffusion model parameters, shows promise for revealing new insights into the cognitive and neural mechanisms of learning and decision making, as well as the alteration of such processes in clinical groups.

The drift diffusion model as the choice rule in reinforcement learning

PubMed Central

Frank, Michael J.

2017-01-01

Current reinforcement-learning models often assume simplified decision processes that do not fully reflect the dynamic complexities of choice processes. Conversely, sequential-sampling models of decision making account for both choice accuracy and response time, but assume that decisions are based on static decision values. To combine these two computational models of decision making and learning, we implemented reinforcement-learning models in which the drift diffusion model describes the choice process, thereby capturing both within- and across-trial dynamics. To exemplify the utility of this approach, we quantitatively fit data from a common reinforcement-learning paradigm using hierarchical Bayesian parameter estimation, and compared model variants to determine whether they could capture the effects of stimulant medication in adult patients with attention-deficit hyper-activity disorder (ADHD). The model with the best relative fit provided a good description of the learning process, choices, and response times. A parameter recovery experiment showed that the hierarchical Bayesian modeling approach enabled accurate estimation of the model parameters. The model approach described here, using simultaneous estimation of reinforcement-learning and drift diffusion model parameters, shows promise for revealing new insights into the cognitive and neural mechanisms of learning and decision making, as well as the alteration of such processes in clinical groups. PMID:27966103

Methods of equipment choice in shotcreting

NASA Astrophysics Data System (ADS)

Sharapov, R. R.; Yadykina, V. V.; Stepanov, M. A.; Kitukov, B. A.

2018-03-01

Shotcrete is widely used in architecture, hydraulic engineering structures, finishing works in tunnels, arc covers and ceilings. The problem of the equipment choice in shotcreting is very important. The main issues influencing the equipment choice are quality improvement and intensification of shotcreting. Main parameters and rational limits of technological characteristic of machines used in solving different problems in shotcreting are described. It is suggested to take into account peculiarities of shotcrete mixing processes and peculiarities of applying these mixtures with compressed air kinetic energy. The described method suggests choosing a mixer with the account of energy capacity, Reynolds number and rotational frequency of the mixing drum. The suggested choice procedure of the equipment nomenclature allows decreasing exploitation costs, increasing the quality of shotcrete and shotcreting in general.

Allowing for MSD prevention during facilities planning for a public service: an a posteriori analysis of 10 library design projects.

PubMed

Bellemare, Marie; Trudel, Louis; Ledoux, Elise; Montreuil, Sylvie; Marier, Micheline; Laberge, Marie; Vincent, Patrick

2006-01-01

Research was conducted to identify an ergonomics-based intervention model designed to factor in musculoskeletal disorder (MSD) prevention when library projects are being designed. The first stage of the research involved an a posteriori analysis of 10 recent redesign projects. The purpose of the analysis was to document perceptions about the attention given to MSD prevention measures over the course of a project on the part of 2 categories of employees: librarians responsible for such projects and personnel working in the libraries before and after changes. Subjects were interviewed in focus groups. Outcomes of the analysis can guide our ergonomic assessment of current situations and contribute to a better understanding of the way inclusion or improvement of prevention measures can support the workplace design process.

A simple robust and accurate a posteriori sub-cell finite volume limiter for the discontinuous Galerkin method on unstructured meshes

NASA Astrophysics Data System (ADS)

Dumbser, Michael; Loubère, Raphaël

2016-08-01

In this paper we propose a simple, robust and accurate nonlinear a posteriori stabilization of the Discontinuous Galerkin (DG) finite element method for the solution of nonlinear hyperbolic PDE systems on unstructured triangular and tetrahedral meshes in two and three space dimensions. This novel a posteriori limiter, which has been recently proposed for the simple Cartesian grid case in [62], is able to resolve discontinuities at a sub-grid scale and is substantially extended here to general unstructured simplex meshes in 2D and 3D. It can be summarized as follows: At the beginning of each time step, an approximation of the local minimum and maximum of the discrete solution is computed for each cell, taking into account also the vertex neighbors of an element. Then, an unlimited discontinuous Galerkin scheme of approximation degree N is run for one time step to produce a so-called candidate solution. Subsequently, an a posteriori detection step checks the unlimited candidate solution at time t n + 1 for positivity, absence of floating point errors and whether the discrete solution has remained within or at least very close to the bounds given by the local minimum and maximum computed in the first step. Elements that do not satisfy all the previously mentioned detection criteria are flagged as troubled cells. For these troubled cells, the candidate solution is discarded as inappropriate and consequently needs to be recomputed. Within these troubled cells the old discrete solution at the previous time tn is scattered onto small sub-cells (Ns = 2 N + 1 sub-cells per element edge), in order to obtain a set of sub-cell averages at time tn. Then, a more robust second order TVD finite volume scheme is applied to update the sub-cell averages within the troubled DG cells from time tn to time t n + 1. The new sub-grid data at time t n + 1 are finally gathered back into a valid cell-centered DG polynomial of degree N by using a classical conservative and higher order

The effects of variations in parameters and algorithm choices on calculated radiomics feature values: initial investigations and comparisons to feature variability across CT image acquisition conditions

NASA Astrophysics Data System (ADS)

Emaminejad, Nastaran; Wahi-Anwar, Muhammad; Hoffman, John; Kim, Grace H.; Brown, Matthew S.; McNitt-Gray, Michael

2018-02-01

Translation of radiomics into clinical practice requires confidence in its interpretations. This may be obtained via understanding and overcoming the limitations in current radiomic approaches. Currently there is a lack of standardization in radiomic feature extraction. In this study we examined a few factors that are potential sources of inconsistency in characterizing lung nodules, such as 1)different choices of parameters and algorithms in feature calculation, 2)two CT image dose levels, 3)different CT reconstruction algorithms (WFBP, denoised WFBP, and Iterative). We investigated the effect of variation of these factors on entropy textural feature of lung nodules. CT images of 19 lung nodules identified from our lung cancer screening program were identified by a CAD tool and contours provided. The radiomics features were extracted by calculating 36 GLCM based and 4 histogram based entropy features in addition to 2 intensity based features. A robustness index was calculated across different image acquisition parameters to illustrate the reproducibility of features. Most GLCM based and all histogram based entropy features were robust across two CT image dose levels. Denoising of images slightly improved robustness of some entropy features at WFBP. Iterative reconstruction resulted in improvement of robustness in a fewer times and caused more variation in entropy feature values and their robustness. Within different choices of parameters and algorithms texture features showed a wide range of variation, as much as 75% for individual nodules. Results indicate the need for harmonization of feature calculations and identification of optimum parameters and algorithms in a radiomics study.

Parameter Estimation and Model Selection in Computational Biology

PubMed Central

Lillacci, Gabriele; Khammash, Mustafa

2010-01-01

A central challenge in computational modeling of biological systems is the determination of the model parameters. Typically, only a fraction of the parameters (such as kinetic rate constants) are experimentally measured, while the rest are often fitted. The fitting process is usually based on experimental time course measurements of observables, which are used to assign parameter values that minimize some measure of the error between these measurements and the corresponding model prediction. The measurements, which can come from immunoblotting assays, fluorescent markers, etc., tend to be very noisy and taken at a limited number of time points. In this work we present a new approach to the problem of parameter selection of biological models. We show how one can use a dynamic recursive estimator, known as extended Kalman filter, to arrive at estimates of the model parameters. The proposed method follows. First, we use a variation of the Kalman filter that is particularly well suited to biological applications to obtain a first guess for the unknown parameters. Secondly, we employ an a posteriori identifiability test to check the reliability of the estimates. Finally, we solve an optimization problem to refine the first guess in case it should not be accurate enough. The final estimates are guaranteed to be statistically consistent with the measurements. Furthermore, we show how the same tools can be used to discriminate among alternate models of the same biological process. We demonstrate these ideas by applying our methods to two examples, namely a model of the heat shock response in E. coli, and a model of a synthetic gene regulation system. The methods presented are quite general and may be applied to a wide class of biological systems where noisy measurements are used for parameter estimation or model selection. PMID:20221262

How the twain can meet: Prospect theory and models of heuristics in risky choice.

PubMed

Pachur, Thorsten; Suter, Renata S; Hertwig, Ralph

2017-03-01

Two influential approaches to modeling choice between risky options are algebraic models (which focus on predicting the overt decisions) and models of heuristics (which are also concerned with capturing the underlying cognitive process). Because they rest on fundamentally different assumptions and algorithms, the two approaches are usually treated as antithetical, or even incommensurable. Drawing on cumulative prospect theory (CPT; Tversky & Kahneman, 1992) as the currently most influential instance of a descriptive algebraic model, we demonstrate how the two modeling traditions can be linked. CPT's algebraic functions characterize choices in terms of psychophysical (diminishing sensitivity to probabilities and outcomes) as well as psychological (risk aversion and loss aversion) constructs. Models of heuristics characterize choices as rooted in simple information-processing principles such as lexicographic and limited search. In computer simulations, we estimated CPT's parameters for choices produced by various heuristics. The resulting CPT parameter profiles portray each of the choice-generating heuristics in psychologically meaningful ways-capturing, for instance, differences in how the heuristics process probability information. Furthermore, CPT parameters can reflect a key property of many heuristics, lexicographic search, and track the environment-dependent behavior of heuristics. Finally, we show, both in an empirical and a model recovery study, how CPT parameter profiles can be used to detect the operation of heuristics. We also address the limits of CPT's ability to capture choices produced by heuristics. Our results highlight an untapped potential of CPT as a measurement tool to characterize the information processing underlying risky choice. Copyright © 2017 Elsevier Inc. All rights reserved.

Differential neurobiological effects of expert advice on risky choice in adolescents and adults.

PubMed

Engelmann, Jan B; Moore, Sara; Monica Capra, C; Berns, Gregory S

2012-06-01

We investigated behavioral and neurobiological mechanisms by which risk-averse advice, provided by an expert, affected risky decisions across three developmental groups [early adolescents (12-14 years), late adolescents (15-17 years), adults (18+ years)]. Using cumulative prospect theory, we modeled choice behavior during a risky-choice task. Results indicate that advice had a significantly greater impact on risky choice in both adolescent groups than in adults. Using functional magnetic resonance imaging, we investigated the neural correlates of this behavioral effect. Developmental effects on correlations between brain activity and valuation parameters were obtained in regions that can be classified into (i) cognitive control regions, such as dorsolateral prefrontal cortex (DLPFC) and ventrolateral PFC; (ii) social cognition regions, such as posterior temporoparietal junction; and (iii) reward-related regions, such as ventromedial PFC (vmPFC) and ventral striatum. Within these regions, differential effects of advice on neural correlates of valuation were observed across development. Specifically, advice increased the correlation strength between brain activity and parameters reflective of safe choice options in adolescent DLPFC and decreased correlation strength between activity and parameters reflective of risky choice options in adult vmPFC. Taken together, results indicate that, across development, distinct brain systems involved in cognitive control and valuation mediate the risk-reducing effect of advice during decision making under risk via specific enhancements and reductions of the correlation strength between brain activity and valuation parameters.

Patient-specific parameter estimation in single-ventricle lumped circulation models under uncertainty

PubMed Central

Schiavazzi, Daniele E.; Baretta, Alessia; Pennati, Giancarlo; Hsia, Tain-Yen; Marsden, Alison L.

2017-01-01

Summary Computational models of cardiovascular physiology can inform clinical decision-making, providing a physically consistent framework to assess vascular pressures and flow distributions, and aiding in treatment planning. In particular, lumped parameter network (LPN) models that make an analogy to electrical circuits offer a fast and surprisingly realistic method to reproduce the circulatory physiology. The complexity of LPN models can vary significantly to account, for example, for cardiac and valve function, respiration, autoregulation, and time-dependent hemodynamics. More complex models provide insight into detailed physiological mechanisms, but their utility is maximized if one can quickly identify patient specific parameters. The clinical utility of LPN models with many parameters will be greatly enhanced by automated parameter identification, particularly if parameter tuning can match non-invasively obtained clinical data. We present a framework for automated tuning of 0D lumped model parameters to match clinical data. We demonstrate the utility of this framework through application to single ventricle pediatric patients with Norwood physiology. Through a combination of local identifiability, Bayesian estimation and maximum a posteriori simplex optimization, we show the ability to automatically determine physiologically consistent point estimates of the parameters and to quantify uncertainty induced by errors and assumptions in the collected clinical data. We show that multi-level estimation, that is, updating the parameter prior information through sub-model analysis, can lead to a significant reduction in the parameter marginal posterior variance. We first consider virtual patient conditions, with clinical targets generated through model solutions, and second application to a cohort of four single-ventricle patients with Norwood physiology. PMID:27155892

Choice of phase in the CS and IOS approximation

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

Snider, R.F.

1982-04-01

With the recognition that the angular momentum representations of unit position and momentum directional states must have different but uniquely related phases, the previously presented expression of scattering amplitude in terms of IOS angle dependent phase shifts must be modified. This resolves a major disagreement between IOS and close coupled degeneracy averaged differential cross sections. It is found that the phase factors appearing in the differential cross section have nothing to do with any particular choice of decoupling parameter. As a consequence, the differential cross section is relatively insensitive to the choice of CS decoupling parameter. The phase relations obtainedmore » are also in agreement with those deduced from the Born approximation.« less

A Simplified Model of Choice Behavior under Uncertainty

PubMed Central

Lin, Ching-Hung; Lin, Yu-Kai; Song, Tzu-Jiun; Huang, Jong-Tsun; Chiu, Yao-Chu

2016-01-01

The Iowa Gambling Task (IGT) has been standardized as a clinical assessment tool (Bechara, 2007). Nonetheless, numerous research groups have attempted to modify IGT models to optimize parameters for predicting the choice behavior of normal controls and patients. A decade ago, most researchers considered the expected utility (EU) model (Busemeyer and Stout, 2002) to be the optimal model for predicting choice behavior under uncertainty. However, in recent years, studies have demonstrated that models with the prospect utility (PU) function are more effective than the EU models in the IGT (Ahn et al., 2008). Nevertheless, after some preliminary tests based on our behavioral dataset and modeling, it was determined that the Ahn et al. (2008) PU model is not optimal due to some incompatible results. This study aims to modify the Ahn et al. (2008) PU model to a simplified model and used the IGT performance of 145 subjects as the benchmark data for comparison. In our simplified PU model, the best goodness-of-fit was found mostly as the value of α approached zero. More specifically, we retested the key parameters α, λ, and A in the PU model. Notably, the influence of the parameters α, λ, and A has a hierarchical power structure in terms of manipulating the goodness-of-fit in the PU model. Additionally, we found that the parameters λ and A may be ineffective when the parameter α is close to zero in the PU model. The present simplified model demonstrated that decision makers mostly adopted the strategy of gain-stay loss-shift rather than foreseeing the long-term outcome. However, there are other behavioral variables that are not well revealed under these dynamic-uncertainty situations. Therefore, the optimal behavioral models may not have been found yet. In short, the best model for predicting choice behavior under dynamic-uncertainty situations should be further evaluated. PMID:27582715

Choice.

PubMed

Greenberg, Jay

2008-09-01

Understanding how and why analysands make the choices they do is central to both the clinical and the theoretical projects of psychoanalysis. And yet we know very little about the process of choice or about the relationship between choices and motives. A striking parallel is to be found between the ways choice is narrated in ancient Greek texts and the experience of analysts as they observe patients making choices in everyday clinical work. Pursuing this convergence of classical and contemporary sensibilities will illuminate crucial elements of the various meanings of choice, and of the way that these meanings change over the course of psychoanalytic treatment.

Finite Element A Posteriori Error Estimation for Heat Conduction. Degree awarded by George Washington Univ.

NASA Technical Reports Server (NTRS)

Lang, Christapher G.; Bey, Kim S. (Technical Monitor)

2002-01-01

This research investigates residual-based a posteriori error estimates for finite element approximations of heat conduction in single-layer and multi-layered materials. The finite element approximation, based upon hierarchical modelling combined with p-version finite elements, is described with specific application to a two-dimensional, steady state, heat-conduction problem. Element error indicators are determined by solving an element equation for the error with the element residual as a source, and a global error estimate in the energy norm is computed by collecting the element contributions. Numerical results of the performance of the error estimate are presented by comparisons to the actual error. Two methods are discussed and compared for approximating the element boundary flux. The equilibrated flux method provides more accurate results for estimating the error than the average flux method. The error estimation is applied to multi-layered materials with a modification to the equilibrated flux method to approximate the discontinuous flux along a boundary at the material interfaces. A directional error indicator is developed which distinguishes between the hierarchical modeling error and the finite element error. Numerical results are presented for single-layered materials which show that the directional indicators accurately determine which contribution to the total error dominates.

Accuracy and Variability of Item Parameter Estimates from Marginal Maximum a Posteriori Estimation and Bayesian Inference via Gibbs Samplers

ERIC Educational Resources Information Center

Wu, Yi-Fang

2015-01-01

Item response theory (IRT) uses a family of statistical models for estimating stable characteristics of items and examinees and defining how these characteristics interact in describing item and test performance. With a focus on the three-parameter logistic IRT (Birnbaum, 1968; Lord, 1980) model, the current study examines the accuracy and…

Quantifying the impact of material-model error on macroscale quantities-of-interest using multiscale a posteriori error-estimation techniques

DOE PAGES

Brown, Judith A.; Bishop, Joseph E.

2016-07-20

An a posteriori error-estimation framework is introduced to quantify and reduce modeling errors resulting from approximating complex mesoscale material behavior with a simpler macroscale model. Such errors may be prevalent when modeling welds and additively manufactured structures, where spatial variations and material textures may be present in the microstructure. We consider a case where a <100> fiber texture develops in the longitudinal scanning direction of a weld. Transversely isotropic elastic properties are obtained through homogenization of a microstructural model with this texture and are considered the reference weld properties within the error-estimation framework. Conversely, isotropic elastic properties are considered approximatemore » weld properties since they contain no representation of texture. Errors introduced by using isotropic material properties to represent a weld are assessed through a quantified error bound in the elastic regime. Lastly, an adaptive error reduction scheme is used to determine the optimal spatial variation of the isotropic weld properties to reduce the error bound.« less

Estimating A Reference Standard Segmentation With Spatially Varying Performance Parameters: Local MAP STAPLE

PubMed Central

Commowick, Olivier; Akhondi-Asl, Alireza; Warfield, Simon K.

2012-01-01

We present a new algorithm, called local MAP STAPLE, to estimate from a set of multi-label segmentations both a reference standard segmentation and spatially varying performance parameters. It is based on a sliding window technique to estimate the segmentation and the segmentation performance parameters for each input segmentation. In order to allow for optimal fusion from the small amount of data in each local region, and to account for the possibility of labels not being observed in a local region of some (or all) input segmentations, we introduce prior probabilities for the local performance parameters through a new Maximum A Posteriori formulation of STAPLE. Further, we propose an expression to compute confidence intervals in the estimated local performance parameters. We carried out several experiments with local MAP STAPLE to characterize its performance and value for local segmentation evaluation. First, with simulated segmentations with known reference standard segmentation and spatially varying performance, we show that local MAP STAPLE performs better than both STAPLE and majority voting. Then we present evaluations with data sets from clinical applications. These experiments demonstrate that spatial adaptivity in segmentation performance is an important property to capture. We compared the local MAP STAPLE segmentations to STAPLE, and to previously published fusion techniques and demonstrate the superiority of local MAP STAPLE over other state-of-the- art algorithms. PMID:22562727

Street choice logit model for visitors in shopping districts.

PubMed

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-09-01

In this study, we propose two models for predicting people's activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that "have more shops, and are wider and lower". In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive).

Street Choice Logit Model for Visitors in Shopping Districts

PubMed Central

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-01-01

In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive). PMID:25379274

A Normalized Direct Approach for Estimating the Parameters of the Normal Ogive Three-Parameter Model for Ability Tests.

ERIC Educational Resources Information Center

Gugel, John F.

A new method for estimating the parameters of the normal ogive three-parameter model for multiple-choice test items--the normalized direct (NDIR) procedure--is examined. The procedure is compared to a more commonly used estimation procedure, Lord's LOGIST, using computer simulations. The NDIR procedure uses the normalized (mid-percentile)…

Do labeled versus unlabeled treatments of alternatives' names influence stated choice outputs? Results from a mode choice study.

PubMed

Jin, Wen; Jiang, Hai; Liu, Yimin; Klampfl, Erica

2017-01-01

Discrete choice experiments have been widely applied to elicit behavioral preferences in the literature. In many of these experiments, the alternatives are named alternatives, meaning that they are naturally associated with specific names. For example, in a mode choice study, the alternatives can be associated with names such as car, taxi, bus, and subway. A fundamental issue that arises in stated choice experiments is whether to treat the alternatives' names as labels (that is, labeled treatment), or as attributes (that is, unlabeled treatment) in the design as well as the presentation phases of the choice sets. In this research, we investigate the impact of labeled versus unlabeled treatments of alternatives' names on the outcome of stated choice experiments, a question that has not been thoroughly investigated in the literature. Using results from a mode choice study, we find that the labeled or the unlabeled treatment of alternatives' names in either the design or the presentation phase of the choice experiment does not statistically affect the estimates of the coefficient parameters. We then proceed to measure the influence toward the willingness-to-pay (WTP) estimates. By using a random-effects model to relate the conditional WTP estimates to the socioeconomic characteristics of the individuals and the labeled versus unlabeled treatments of alternatives' names, we find that: a) Given the treatment of alternatives' names in the presentation phase, the treatment of alternatives' names in the design phase does not statistically affect the estimates of the WTP measures; and b) Given the treatment of alternatives' names in the design phase, the labeled treatment of alternatives' names in the presentation phase causes the corresponding WTP estimates to be slightly higher.

Do labeled versus unlabeled treatments of alternatives’ names influence stated choice outputs? Results from a mode choice study

PubMed Central

Jin, Wen; Jiang, Hai; Liu, Yimin; Klampfl, Erica

2017-01-01

Discrete choice experiments have been widely applied to elicit behavioral preferences in the literature. In many of these experiments, the alternatives are named alternatives, meaning that they are naturally associated with specific names. For example, in a mode choice study, the alternatives can be associated with names such as car, taxi, bus, and subway. A fundamental issue that arises in stated choice experiments is whether to treat the alternatives’ names as labels (that is, labeled treatment), or as attributes (that is, unlabeled treatment) in the design as well as the presentation phases of the choice sets. In this research, we investigate the impact of labeled versus unlabeled treatments of alternatives’ names on the outcome of stated choice experiments, a question that has not been thoroughly investigated in the literature. Using results from a mode choice study, we find that the labeled or the unlabeled treatment of alternatives’ names in either the design or the presentation phase of the choice experiment does not statistically affect the estimates of the coefficient parameters. We then proceed to measure the influence toward the willingness-to-pay (WTP) estimates. By using a random-effects model to relate the conditional WTP estimates to the socioeconomic characteristics of the individuals and the labeled versus unlabeled treatments of alternatives’ names, we find that: a) Given the treatment of alternatives’ names in the presentation phase, the treatment of alternatives’ names in the design phase does not statistically affect the estimates of the WTP measures; and b) Given the treatment of alternatives’ names in the design phase, the labeled treatment of alternatives’ names in the presentation phase causes the corresponding WTP estimates to be slightly higher. PMID:28806764

Marketing Secondary Schools to Parents--Some Lessons from the Research on Parental Choice.

ERIC Educational Resources Information Center

Smedley, Don

1995-01-01

Reviews the literature on parental choice and suggests implications for the marketing of secondary schools in England. The parameters of parental choice may change as schools become more active at marketing and parents become more sophisticated in their choosing strategies. However, schools may become increasingly disenchanted with the competitive…

Enhanced nearfield acoustic holography for larger distances of reconstructions using fixed parameter Tikhonov regularization

DOE PAGES

Chelliah, Kanthasamy; Raman, Ganesh G.; Muehleisen, Ralph T.

2016-07-07

This paper evaluates the performance of various regularization parameter choice methods applied to different approaches of nearfield acoustic holography when a very nearfield measurement is not possible. For a fixed grid resolution, the larger the hologram distance, the larger the error in the naive nearfield acoustic holography reconstructions. These errors can be smoothed out by using an appropriate order of regularization. In conclusion, this study shows that by using a fixed/manual choice of regularization parameter, instead of automated parameter choice methods, reasonably accurate reconstructions can be obtained even when the hologram distance is 16 times larger than the grid resolution.

An objective rationale for the choice of regularisation parameter with application to global multiple-frequency S-wave tomography

NASA Astrophysics Data System (ADS)

Zaroli, C.; Sambridge, M.; Lévêque, J.-J.; Debayle, E.; Nolet, G.

2013-06-01

In a linear ill-posed inverse problem, the regularisation parameter (damping) controls the balance between minimising both the residual data misfit and the model norm. Poor knowledge of data uncertainties often makes the selection of damping rather arbitrary. To go beyond that subjectivity, an objective rationale for the choice of damping is presented, which is based on the coherency of delay-time estimates in different frequency bands. Our method is tailored to the problem of global Multiple-Frequency Tomography (MFT), using a data set of 287 078 S-wave delay-times measured in five frequency bands (10, 15, 22, 34, 51 s central periods). Whereas for each ray path the delay-time estimates should vary coherently from one period to the other, the noise most likely is not coherent. Thus, the lack of coherency of the information in different frequency bands is exploited, using an analogy with the cross-validation method, to identify models dominated by noise. In addition, a sharp change of behaviour of the model ℓ∞-norm, as the damping becomes lower than a threshold value, is interpreted as the signature of data noise starting to significantly pollute at least one model component. Models with damping larger than this threshold are diagnosed as being constructed with poor data exploitation. Finally, a preferred model is selected from the remaining range of permitted model solutions. This choice is quasi-objective in terms of model interpretation, as the selected model shows a high degree of similarity with almost all other permitted models (correlation superior to 98% up to spherical harmonic degree 80). The obtained tomographic model is displayed in mid lower-mantle (660-1910 km depth), and is shown to be compatible with three other recent global shear-velocity models. A wider application of the presented rationale should permit us to converge towards more objective seismic imaging of the Earth's mantle.

Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

PubMed Central

Kirkpatrick, Kimberly; Marshall, Andrew T.; Smith, Aaron P.

2016-01-01

Individual differences in impulsive and risky choice are key risk factors for a variety of maladaptive behaviors such as drug abuse, gambling, and obesity. In our rat model, ordered individual differences are stable across choice parameters, months of testing, and span a broad spectrum, suggesting that rats, like humans, exhibit trait-level impulsive and risky choice behaviors. In addition, impulsive and risky choices are highly correlated, suggesting a degree of correlation between these two traits. An examination of the underlying cognitive mechanisms has suggested an important role for timing processes in impulsive choice. In addition, in an examination of genetic factors in impulsive choice, the Lewis rat strain emerged as a possible animal model for studying disordered impulsive choice, with this strain demonstrating deficient delay processing. Early rearing environment also affected impulsive behaviors, with rearing in an enriched environment promoting adaptable and more self-controlled choices. The combined results with impulsive choice suggest an important role for timing and reward sensitivity in moderating impulsive behaviors. Relative reward valuation also affects risky choice, with manipulation of objective reward value (relative to an alternative reference point) resulting in loss chasing behaviors that predicted overall risky choice behaviors. The combined results are discussed in relation to domain-specific versus domain-general subjective reward valuation processes and the potential neural substrates of impulsive and risky choice. PMID:27695580

A three-step maximum a posteriori probability method for InSAR data inversion of coseismic rupture with application to the 14 April 2010 Mw 6.9 Yushu, China, earthquake

NASA Astrophysics Data System (ADS)

Sun, Jianbao; Shen, Zheng-Kang; Bürgmann, Roland; Wang, Min; Chen, Lichun; Xu, Xiwei

2013-08-01

develop a three-step maximum a posteriori probability method for coseismic rupture inversion, which aims at maximizing the a posterior probability density function (PDF) of elastic deformation solutions of earthquake rupture. The method originates from the fully Bayesian inversion and mixed linear-nonlinear Bayesian inversion methods and shares the same posterior PDF with them, while overcoming difficulties with convergence when large numbers of low-quality data are used and greatly improving the convergence rate using optimization procedures. A highly efficient global optimization algorithm, adaptive simulated annealing, is used to search for the maximum of a posterior PDF ("mode" in statistics) in the first step. The second step inversion approaches the "true" solution further using the Monte Carlo inversion technique with positivity constraints, with all parameters obtained from the first step as the initial solution. Then slip artifacts are eliminated from slip models in the third step using the same procedure of the second step, with fixed fault geometry parameters. We first design a fault model with 45° dip angle and oblique slip, and produce corresponding synthetic interferometric synthetic aperture radar (InSAR) data sets to validate the reliability and efficiency of the new method. We then apply this method to InSAR data inversion for the coseismic slip distribution of the 14 April 2010 Mw 6.9 Yushu, China earthquake. Our preferred slip model is composed of three segments with most of the slip occurring within 15 km depth and the maximum slip reaches 1.38 m at the surface. The seismic moment released is estimated to be 2.32e+19 Nm, consistent with the seismic estimate of 2.50e+19 Nm.

A Scalar Product Model for the Multidimensional Scaling of Choice

ERIC Educational Resources Information Center

Bechtel, Gordon G.; And Others

1971-01-01

Contains a solution for the multidimensional scaling of pairwise choice when individuals are represented as dimensional weights. The analysis supplies an exact least squares solution and estimates of group unscalability parameters. (DG)

Comparison between three option, four option and five option multiple choice question tests for quality parameters: A randomized study.

PubMed

Vegada, Bhavisha; Shukla, Apexa; Khilnani, Ajeetkumar; Charan, Jaykaran; Desai, Chetna

2016-01-01

Most of the academic teachers use four or five options per item of multiple choice question (MCQ) test as formative and summative assessment. Optimal number of options in MCQ item is a matter of considerable debate among academic teachers of various educational fields. There is a scarcity of the published literature regarding the optimum number of option in each item of MCQ in the field of medical education. To compare three options, four options, and five options MCQs test for the quality parameters - reliability, validity, item analysis, distracter analysis, and time analysis. Participants were 3 rd semester M.B.B.S. students. Students were divided randomly into three groups. Each group was given one set of MCQ test out of three options, four options, and five option randomly. Following the marking of the multiple choice tests, the participants' option selections were analyzed and comparisons were conducted of the mean marks, mean time, validity, reliability and facility value, discrimination index, point biserial value, distracter analysis of three different option formats. Students score more ( P = 0.000) and took less time ( P = 0.009) for the completion of three options as compared to four options and five options groups. Facility value was more ( P = 0.004) in three options group as compared to four and five options groups. There was no significant difference between three groups for the validity, reliability, and item discrimination. Nonfunctioning distracters were more in the four and five options group as compared to three option group. Assessment based on three option MCQs is can be preferred over four option and five option MCQs.

Psychophysics of time perception and intertemporal choice models

NASA Astrophysics Data System (ADS)

Takahashi, Taiki; Oono, Hidemi; Radford, Mark H. B.

2008-03-01

Intertemporal choice and psychophysics of time perception have been attracting attention in econophysics and neuroeconomics. Several models have been proposed for intertemporal choice: exponential discounting, general hyperbolic discounting (exponential discounting with logarithmic time perception of the Weber-Fechner law, a q-exponential discount model based on Tsallis's statistics), simple hyperbolic discounting, and Stevens' power law-exponential discounting (exponential discounting with Stevens' power time perception). In order to examine the fitness of the models for behavioral data, we estimated the parameters and AICc (Akaike Information Criterion with small sample correction) of the intertemporal choice models by assessing the points of subjective equality (indifference points) at seven delays. Our results have shown that the orders of the goodness-of-fit for both group and individual data were [Weber-Fechner discounting (general hyperbola) > Stevens' power law discounting > Simple hyperbolic discounting > Exponential discounting], indicating that human time perception in intertemporal choice may follow the Weber-Fechner law. Indications of the results for neuropsychopharmacological treatments of addiction and biophysical processing underlying temporal discounting and time perception are discussed.

Semiparametric Thurstonian Models for Recurrent Choices: A Bayesian Analysis

ERIC Educational Resources Information Center

Ansari, Asim; Iyengar, Raghuram

2006-01-01

We develop semiparametric Bayesian Thurstonian models for analyzing repeated choice decisions involving multinomial, multivariate binary or multivariate ordinal data. Our modeling framework has multiple components that together yield considerable flexibility in modeling preference utilities, cross-sectional heterogeneity and parameter-driven…

A priori and a posteriori approaches for finding genes of evolutionary interest in non-model species: osmoregulatory genes in the kidney transcriptome of the desert rodent Dipodomys spectabilis (banner-tailed kangaroo rat).

PubMed

Marra, Nicholas J; Eo, Soo Hyung; Hale, Matthew C; Waser, Peter M; DeWoody, J Andrew

2012-12-01

One common goal in evolutionary biology is the identification of genes underlying adaptive traits of evolutionary interest. Recently next-generation sequencing techniques have greatly facilitated such evolutionary studies in species otherwise depauperate of genomic resources. Kangaroo rats (Dipodomys sp.) serve as exemplars of adaptation in that they inhabit extremely arid environments, yet require no drinking water because of ultra-efficient kidney function and osmoregulation. As a basis for identifying water conservation genes in kangaroo rats, we conducted a priori bioinformatics searches in model rodents (Mus musculus and Rattus norvegicus) to identify candidate genes with known or suspected osmoregulatory function. We then obtained 446,758 reads via 454 pyrosequencing to characterize genes expressed in the kidney of banner-tailed kangaroo rats (Dipodomys spectabilis). We also determined candidates a posteriori by identifying genes that were overexpressed in the kidney. The kangaroo rat sequences revealed nine different a priori candidate genes predicted from our Mus and Rattus searches, as well as 32 a posteriori candidate genes that were overexpressed in kidney. Mutations in two of these genes, Slc12a1 and Slc12a3, cause human renal diseases that result in the inability to concentrate urine. These genes are likely key determinants of physiological water conservation in desert rodents. Copyright © 2012 Elsevier Inc. All rights reserved.

A Probabilistic, Dynamic, and Attribute-wise Model of Intertemporal Choice

PubMed Central

Dai, Junyi; Busemeyer, Jerome R.

2014-01-01

Most theoretical and empirical research on intertemporal choice assumes a deterministic and static perspective, leading to the widely adopted delay discounting models. As a form of preferential choice, however, intertemporal choice may be generated by a stochastic process that requires some deliberation time to reach a decision. We conducted three experiments to investigate how choice and decision time varied as a function of manipulations designed to examine the delay duration effect, the common difference effect, and the magnitude effect in intertemporal choice. The results, especially those associated with the delay duration effect, challenged the traditional deterministic and static view and called for alternative approaches. Consequently, various static or dynamic stochastic choice models were explored and fit to the choice data, including alternative-wise models derived from the traditional exponential or hyperbolic discount function and attribute-wise models built upon comparisons of direct or relative differences in money and delay. Furthermore, for the first time, dynamic diffusion models, such as those based on decision field theory, were also fit to the choice and response time data simultaneously. The results revealed that the attribute-wise diffusion model with direct differences, power transformations of objective value and time, and varied diffusion parameter performed the best and could account for all three intertemporal effects. In addition, the empirical relationship between choice proportions and response times was consistent with the prediction of diffusion models and thus favored a stochastic choice process for intertemporal choice that requires some deliberation time to make a decision. PMID:24635188

Evolving Choice Inconsistencies in Choice of Prescription Drug Insurance

PubMed Central

ABALUCK, JASON

2017-01-01

We study choice over prescription insurance plans by the elderly using government administrative data to evaluate how these choices evolve over time. We find large “foregone savings” from not choosing the lowest cost plan that has grown over time. We develop a structural framework to decompose the changes in “foregone welfare” from inconsistent choices into choice set changes and choice function changes from a fixed choice set. We find that foregone welfare increases over time due primarily to changes in plan characteristics such as premiums and out-of-pocket costs; we estimate little learning at either the individual or cohort level. PMID:29104294

Noisy Preferences in Risky Choice: A Cautionary Note

PubMed Central

2017-01-01

We examine the effects of multiple sources of noise in risky decision making. Noise in the parameters that characterize an individual’s preferences can combine with noise in the response process to distort observed choice proportions. Thus, underlying preferences that conform to expected value maximization can appear to show systematic risk aversion or risk seeking. Similarly, core preferences that are consistent with expected utility theory, when perturbed by such noise, can appear to display nonlinear probability weighting. For this reason, modal choices cannot be used simplistically to infer underlying preferences. Quantitative model fits that do not allow for both sorts of noise can lead to wrong conclusions. PMID:28569526

Informed choice and deaf children: underpinning concepts and enduring challenges.

PubMed

Young, Alys; Carr, Gwen; Hunt, Ros; McCracken, Wendy; Skipp, Amy; Tattersall, Helen

2006-01-01

This article concerns the first stage of a research and development project that aimed to produce both parent and professional guidelines on the promotion and provision of informed choice for families with deaf children. It begins with a theoretical discussion of the problems associated with the concept of informed choice and deaf child services and then focuses specifically on why a metastudy approach was employed to address both the overcontextualized debate about informed choice when applied to deaf children and the problems associated with its investigation in practice with families and professionals. It presents a detailed analysis of the conceptual relevance of a range of identified studies "outside" the field of deafness. These are ordered according to 2 main conceptual categories and 7 subcategories-(a) the nature of information: "information that is evaluative, not just descriptive"; "the difficulties of information for a purpose"; "the origins and status of information"; and "informed choice and knowledge, not informed choice and information" and (b) parameters and definitions of choice: "informed choice as absolute and relative concept", "preferences and presumptions of rationality", and "informed choice for whom?" Relevant deaf child literature is integrated into the discussion of each conceptual debate in order both to expand and challenge current usage of informed choice as applied to deaf children and families and to delineate possible directions in the planning of the next stage of the main project aimed at producing parent/professional guidelines.

Aporrectodea caliginosa, a relevant earthworm species for a posteriori pesticide risk assessment: current knowledge and recommendations for culture and experimental design.

PubMed

Bart, Sylvain; Amossé, Joël; Lowe, Christopher N; Mougin, Christian; Péry, Alexandre R R; Pelosi, Céline

2018-06-21

Ecotoxicological tests with earthworms are widely used and are mandatory for the risk assessment of pesticides prior to registration and commercial use. The current model species for standardized tests is Eisenia fetida or Eisenia andrei. However, these species are absent from agricultural soils and often less sensitive to pesticides than other earthworm species found in mineral soils. To move towards a better assessment of pesticide effects on non-target organisms, there is a need to perform a posteriori tests using relevant species. The endogeic species Aporrectodea caliginosa (Savigny, 1826) is representative of cultivated fields in temperate regions and is suggested as a relevant model test species. After providing information on its taxonomy, biology, and ecology, we reviewed current knowledge concerning its sensitivity towards pesticides. Moreover, we highlighted research gaps and promising perspectives. Finally, advice and recommendations are given for the establishment of laboratory cultures and experiments using this soil-dwelling earthworm species.

Adolescents’ Food Choice and the Place of Plant-Based Foods

PubMed Central

Ensaff, Hannah; Coan, Susan; Sahota, Pinki; Braybrook, Debbie; Akter, Humaira; McLeod, Helen

2015-01-01

A diet dominated by plant foods, with limited amounts of refined processed foods and animal products conveys substantial health benefits. This study sought to explore adolescents’ attitudes and perceptions towards plant-based foods. Semi-structured focus group interviews were conducted with adolescents (age 14–15 years) (n = 29) attending an inner city school in Yorkshire, UK. Using a grounded theory methodology, data analysis provided four main categories and related concepts revolving around adolescents’ perspectives on plant-based foods: food choice parameters; perceived drivers and benefits of plant-based foods; environmental food cues; barriers to plant-based food choice. In the emergent grounded theory, a clear disconnect between plant-based foods and the parameters that adolescents use to make food choices, is highlighted. Further, key barriers to adolescents adopting a plant-based diet are differentiated and considered with respect to practice and policy. The analysis offers a framework to remodel and re-present plant-based foods. In this way, it is proposed that a closer connection is possible, with consequent shifts in adolescents’ dietary behaviour towards a more plant-based diet and associated health benefits. PMID:26066012

Adolescents' Food Choice and the Place of Plant-Based Foods.

PubMed

Ensaff, Hannah; Coan, Susan; Sahota, Pinki; Braybrook, Debbie; Akter, Humaira; McLeod, Helen

2015-06-09

A diet dominated by plant foods, with limited amounts of refined processed foods and animal products conveys substantial health benefits. This study sought to explore adolescents' attitudes and perceptions towards plant-based foods. Semi-structured focus group interviews were conducted with adolescents (age 14-15 years) (n = 29) attending an inner city school in Yorkshire, UK. Using a grounded theory methodology, data analysis provided four main categories and related concepts revolving around adolescents' perspectives on plant-based foods: food choice parameters; perceived drivers and benefits of plant-based foods; environmental food cues; barriers to plant-based food choice. In the emergent grounded theory, a clear disconnect between plant-based foods and the parameters that adolescents use to make food choices, is highlighted. Further, key barriers to adolescents adopting a plant-based diet are differentiated and considered with respect to practice and policy. The analysis offers a framework to remodel and re-present plant-based foods. In this way, it is proposed that a closer connection is possible, with consequent shifts in adolescents' dietary behaviour towards a more plant-based diet and associated health benefits.

Multitasking as a choice: a perspective.

PubMed

Broeker, Laura; Liepelt, Roman; Poljac, Edita; Künzell, Stefan; Ewolds, Harald; de Oliveira, Rita F; Raab, Markus

2018-01-01

Performance decrements in multitasking have been explained by limitations in cognitive capacity, either modelled as static structural bottlenecks or as the scarcity of overall cognitive resources that prevent humans, or at least restrict them, from processing two tasks at the same time. However, recent research has shown that individual differences, flexible resource allocation, and prioritization of tasks cannot be fully explained by these accounts. We argue that understanding human multitasking as a choice and examining multitasking performance from the perspective of judgment and decision-making (JDM), may complement current dual-task theories. We outline two prominent theories from the area of JDM, namely Simple Heuristics and the Decision Field Theory, and adapt these theories to multitasking research. Here, we explain how computational modelling techniques and decision-making parameters used in JDM may provide a benefit to understanding multitasking costs and argue that these techniques and parameters have the potential to predict multitasking behavior in general, and also individual differences in behavior. Finally, we present the one-reason choice metaphor to explain a flexible use of limited capacity as well as changes in serial and parallel task processing. Based on this newly combined approach, we outline a concrete interdisciplinary future research program that we think will help to further develop multitasking research.

Neuroforecasting Aggregate Choice

PubMed Central

Knutson, Brian; Genevsky, Alexander

2018-01-01

Advances in brain-imaging design and analysis have allowed investigators to use neural activity to predict individual choice, while emerging Internet markets have opened up new opportunities for forecasting aggregate choice. Here, we review emerging research that bridges these levels of analysis by attempting to use group neural activity to forecast aggregate choice. A survey of initial findings suggests that components of group neural activity might forecast aggregate choice, in some cases even beyond traditional behavioral measures. In addition to demonstrating the plausibility of neuroforecasting, these findings raise the possibility that not all neural processes that predict individual choice forecast aggregate choice to the same degree. We propose that although integrative choice components may confer more consistency within individuals, affective choice components may generalize more broadly across individuals to forecast aggregate choice. PMID:29706726

Free choice and career choice: Clerkship electives in medical education.

PubMed

Mihalynuk, Tanis; Leung, Gentson; Fraser, Joan; Bates, Joanna; Snadden, David

2006-11-01

Medical education experiences, particularly in clinical years, are reported determinants of career choice. Less is known about features of clinical education experiences including length, discipline, setting and choice, which may serve as landmarks in career choice decisions. This study's purpose was to explore the benefits of a free choice clerkship elective, and more specifically, its role in clarifying career choice. Using framework and content analysis methodology, we analysed University of British Columbia, third-year medical student anonymised assignments regarding free choice and 2-week clerkship elective experiences. This clerkship was designed to provide students with clerkship experiences outside the conventional curricular model, while encouraging student choice of ambulatory and community settings. Assignment questions included: reasons for choosing elective; whether learning objectives were met; influence of elective on career choice; and unique elective experiences. Iterative review, coding, analysis and indexing of assignments were carried out to identify themes and corroborate findings. Emergent themes included: positive views of experience; transferable knowledge and skills; and influencer of future education and career choices. Although students were encouraged to choose clerkship experiences outside the conventional curricular model, most students chose the elective to clarify future career decisions. This qualitative descriptive study highlights the influence of highly regarded, free choice clerkship elective experiences in the career decision making process in medical education. Further examination of the details of clerkship elective experiences which influence career choice is recommended.

An objective rationale for the choice of regularisation parameter with application to global multiple-frequency S-wave tomography

NASA Astrophysics Data System (ADS)

Zaroli, C.; Sambridge, M.; Lévêque, J.-J.; Debayle, E.; Nolet, G.

2013-10-01

In a linear ill-posed inverse problem, the regularisation parameter (damping) controls the balance between minimising both the residual data misfit and the model norm. Poor knowledge of data uncertainties often makes the selection of damping rather arbitrary. To go beyond that subjectivity, an objective rationale for the choice of damping is presented, which is based on the coherency of delay-time estimates in different frequency bands. Our method is tailored to the problem of global multiple-frequency tomography (MFT), using a data set of 287 078 S-wave delay times measured in five frequency bands (10, 15, 22, 34, and 51 s central periods). Whereas for each ray path the delay-time estimates should vary coherently from one period to the other, the noise most likely is not coherent. Thus, the lack of coherency of the information in different frequency bands is exploited, using an analogy with the cross-validation method, to identify models dominated by noise. In addition, a sharp change of behaviour of the model ℓ∞-norm, as the damping becomes lower than a threshold value, is interpreted as the signature of data noise starting to significantly pollute at least one model component. Models with damping larger than this threshold are diagnosed as being constructed with poor data exploitation. Finally, a preferred model is selected from the remaining range of permitted model solutions. This choice is quasi-objective in terms of model interpretation, as the selected model shows a high degree of similarity with almost all other permitted models (correlation superior to 98% up to spherical harmonic degree 80). The obtained tomographic model is displayed in the mid lower-mantle (660-1910 km depth), and is shown to be compatible with three other recent global shear-velocity models. A wider application of the presented rationale should permit us to converge towards more objective seismic imaging of Earth's mantle.

Cognitive Models of Risky Choice: Parameter Stability and Predictive Accuracy of Prospect Theory

ERIC Educational Resources Information Center

Glockner, Andreas; Pachur, Thorsten

2012-01-01

In the behavioral sciences, a popular approach to describe and predict behavior is cognitive modeling with adjustable parameters (i.e., which can be fitted to data). Modeling with adjustable parameters allows, among other things, measuring differences between people. At the same time, parameter estimation also bears the risk of overfitting. Are…

Estimation of Dynamic Discrete Choice Models by Maximum Likelihood and the Simulated Method of Moments

PubMed Central

Eisenhauer, Philipp; Heckman, James J.; Mosso, Stefano

2015-01-01

We compare the performance of maximum likelihood (ML) and simulated method of moments (SMM) estimation for dynamic discrete choice models. We construct and estimate a simplified dynamic structural model of education that captures some basic features of educational choices in the United States in the 1980s and early 1990s. We use estimates from our model to simulate a synthetic dataset and assess the ability of ML and SMM to recover the model parameters on this sample. We investigate the performance of alternative tuning parameters for SMM. PMID:26494926

Noisy preferences in risky choice: A cautionary note.

PubMed

Bhatia, Sudeep; Loomes, Graham

2017-10-01

We examine the effects of multiple sources of noise in risky decision making. Noise in the parameters that characterize an individual's preferences can combine with noise in the response process to distort observed choice proportions. Thus, underlying preferences that conform to expected value maximization can appear to show systematic risk aversion or risk seeking. Similarly, core preferences that are consistent with expected utility theory, when perturbed by such noise, can appear to display nonlinear probability weighting. For this reason, modal choices cannot be used simplistically to infer underlying preferences. Quantitative model fits that do not allow for both sorts of noise can lead to wrong conclusions. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Not all choices are created equal: Task-relevant choices enhance motor learning compared to task-irrelevant choices.

PubMed

Carter, Michael J; Ste-Marie, Diane M

2017-12-01

Lewthwaite et al. (2015) reported that the learning benefits of exercising choice (i.e., their self-controlled condition) are not restricted to task-relevant features (e.g., feedback). They found that choosing one's golf ball color (Exp. 1) or choosing which of two tasks to perform at a later time plus which of two artworks to hang (Exp. 2) resulted in better retention than did being denied these same choices (i.e., yoked condition). The researchers concluded that the learning benefits derived from choice, whether irrelevant or relevant to the to-be-learned task, are predominantly motivational because choice is intrinsically rewarding and satisfies basic psychological needs. However, the absence of a group that made task-relevant choices and the lack of psychological measures significantly weakened their conclusions. Here, we investigated how task-relevant and task-irrelevant choices affect motor-skill learning. Participants practiced a spatiotemporal motor task in either a task-relevant group (choice over feedback schedule), a task-irrelevant group (choice over the color of an arm-wrap plus game selection), or a no-choice group. The results showed significantly greater learning in the task-relevant group than in both the task-irrelevant and no-choice groups, who did not differ significantly. Critically, these learning differences were not attributed to differences in perceptions of competence or autonomy, but instead to superior error-estimation abilities. These results challenge the perspective that motivational influences are the root cause of self-controlled learning advantages. Instead, the findings add to the growing evidence highlighting that the informational value gained from task-relevant choices makes a greater relative contribution to these advantages than motivational influences do.

Modelling of turbulent lifted jet flames using flamelets: a priori assessment and a posteriori validation

NASA Astrophysics Data System (ADS)

Ruan, Shaohong; Swaminathan, Nedunchezhian; Darbyshire, Oliver

2014-03-01

This study focuses on the modelling of turbulent lifted jet flames using flamelets and a presumed Probability Density Function (PDF) approach with interest in both flame lift-off height and flame brush structure. First, flamelet models used to capture contributions from premixed and non-premixed modes of the partially premixed combustion in the lifted jet flame are assessed using a Direct Numerical Simulation (DNS) data for a turbulent lifted hydrogen jet flame. The joint PDFs of mixture fraction Z and progress variable c, including their statistical correlation, are obtained using a copula method, which is also validated using the DNS data. The statistically independent PDFs are found to be generally inadequate to represent the joint PDFs from the DNS data. The effects of Z-c correlation and the contribution from the non-premixed combustion mode on the flame lift-off height are studied systematically by including one effect at a time in the simulations used for a posteriori validation. A simple model including the effects of chemical kinetics and scalar dissipation rate is suggested and used for non-premixed combustion contributions. The results clearly show that both Z-c correlation and non-premixed combustion effects are required in the premixed flamelets approach to get good agreement with the measured flame lift-off heights as a function of jet velocity. The flame brush structure reported in earlier experimental studies is also captured reasonably well for various axial positions. It seems that flame stabilisation is influenced by both premixed and non-premixed combustion modes, and their mutual influences.

Using psychophysics to ask if the brain samples or maximizes

PubMed Central

Acuna, Daniel E.; Berniker, Max; Fernandes, Hugo L.; Kording, Konrad P.

2015-01-01

The two-alternative forced-choice (2AFC) task is the workhorse of psychophysics and is used to measure the just-noticeable difference, generally assumed to accurately quantify sensory precision. However, this assumption is not true for all mechanisms of decision making. Here we derive the behavioral predictions for two popular mechanisms, sampling and maximum a posteriori, and examine how they affect the outcome of the 2AFC task. These predictions are used in a combined visual 2AFC and estimation experiment. Our results strongly suggest that subjects use a maximum a posteriori mechanism. Further, our derivations and experimental paradigm establish the already standard 2AFC task as a behavioral tool for measuring how humans make decisions under uncertainty. PMID:25767093

A density-functional study on the electronic and vibrational properties of layered antimony telluride.

PubMed

Stoffel, Ralf P; Deringer, Volker L; Simon, Ronnie E; Hermann, Raphaël P; Dronskowski, Richard

2015-03-04

We present a comprehensive survey of electronic and lattice-dynamical properties of crystalline antimony telluride (Sb2Te3). In a first step, the electronic structure and chemical bonding have been investigated, followed by calculations of the atomic force constants, phonon dispersion relationships and densities of states. Then, (macroscopic) physical properties of Sb2Te3 have been computed, namely, the atomic thermal displacement parameters, the Grüneisen parameter γ, the volume expansion of the lattice, and finally the bulk modulus B. We compare theoretical results from three popular and economic density-functional theory (DFT) approaches: the local density approximation (LDA), the generalized gradient approximation (GGA), and a posteriori dispersion corrections to the latter. Despite its simplicity, the LDA shows excellent performance for all properties investigated-including the Grüneisen parameter, which only the LDA is able to recover with confidence. In the absence of computationally more demanding hybrid DFT methods, the LDA seems to be a good choice for further lattice dynamical studies of Sb2Te3 and related layered telluride materials.

Cultures of choice: towards a sociology of choice as a cultural phenomenon.

PubMed

Schwarz, Ori

2017-09-07

The article explores different ways to conceptualize the relationship between choice and culture. These two notions are often constructed as opposites: while sociologies of modernization (such as Giddens') portray a shift from cultural traditions to culturally disembedded choice, dispositional sociologies (such as Bourdieu's) uncover cultural determination as the hidden truth behind apparent choice. However, choice may be real and cultural simultaneously. Culture moulds choice not only by inculcating dispositions or shaping repertoires of alternatives, but also by offering culturally specific choice practices, ways of choosing embedded in meaning, normativity, and materiality; and by shaping attributions of choice in everyday life. By bringing together insights from rival schools, I portray an outline for a comparative cultural sociology of choice, and demonstrate its purchase while discussing the digitalization of choice; and cultural logics that shape choice attribution in ways opposing neoliberal trends. © London School of Economics and Political Science 2017.

A Monte Carlo study of the impact of the choice of rectum volume definition on estimates of equivalent uniform doses and the volume parameter

NASA Astrophysics Data System (ADS)

Kvinnsland, Yngve; Muren, Ludvig Paul; Dahl, Olav

2004-08-01

Calculations of normal tissue complication probability (NTCP) values for the rectum are difficult because it is a hollow, non-rigid, organ. Finding the true cumulative dose distribution for a number of treatment fractions requires a CT scan before each treatment fraction. This is labour intensive, and several surrogate distributions have therefore been suggested, such as dose wall histograms, dose surface histograms and histograms for the solid rectum, with and without margins. In this study, a Monte Carlo method is used to investigate the relationships between the cumulative dose distributions based on all treatment fractions and the above-mentioned histograms that are based on one CT scan only, in terms of equivalent uniform dose. Furthermore, the effect of a specific choice of histogram on estimates of the volume parameter of the probit NTCP model was investigated. It was found that the solid rectum and the rectum wall histograms (without margins) gave equivalent uniform doses with an expected value close to the values calculated from the cumulative dose distributions in the rectum wall. With the number of patients available in this study the standard deviations of the estimates of the volume parameter were large, and it was not possible to decide which volume gave the best estimates of the volume parameter, but there were distinct differences in the mean values of the values obtained.

Action and Valence Modulate Choice and Choice-Induced Preference Change

PubMed Central

Koster, Raphael; Duzel, Emrah; Dolan, Raymond J.

2015-01-01

Choices are not only communicated via explicit actions but also passively through inaction. In this study we investigated how active or passive choice impacts upon the choice process itself as well as a preference change induced by choice. Subjects were tasked to select a preference for unfamiliar photographs by action or inaction, before and after they gave valuation ratings for all photographs. We replicate a finding that valuation increases for chosen items and decreases for unchosen items compared to a control condition in which the choice was made post re-evaluation. Whether choice was expressed actively or passively affected the dynamics of revaluation differently for positive and negatively valenced items. Additionally, the choice itself was biased towards action such that subjects tended to choose a photograph obtained by action more often than a photographed obtained through inaction. These results highlight intrinsic biases consistent with a tight coupling of action and reward and add to an emerging understanding of how the mode of action itself, and not just an associated outcome, modulates the decision making process. PMID:25747703

Changing choices: disabled and chronically ill people's experiences of reconsidering choices.

PubMed

Baxter, Kate

2013-06-01

To increase understanding of disabled and chronically ill people's experiences of revisiting choices by considering events that prompted people to reconsider choices; what factors motivated them to act upon these events and what factors affected their experiences of revisiting choices. A sub-sample of 20 disabled and chronically ill people who took part in a qualitative, longitudinal study exploring choice-making in the context of changing circumstances. Each person was interviewed three times. Analysis focussed on choices that people had been prompted to revisit. Most choices were about health or social care and were revisited within a year due to: changes in health or social circumstances; poorer than expected outcomes; and external interventions. People were motivated to make changes by a desire to maintain independence and control, but perceived short-term costs of decision-making could act as a deterrent. Experiences of revisiting choices were affected by help from other people and emotional strength. Making and revisiting choices is complex; people need support to engage with the continual cycle of choice-making. People who instigate revisions of their own accord may be particularly vulnerable to lack of support.

Impulsive Choice and Workplace Safety: A New Area of Inquiry for Research in Occupational Settings

ERIC Educational Resources Information Center

Reynolds, Brady; Schiffbauer, Ryan M.

2004-01-01

A conceptual argument is presented for the relevance of behavior-analytic research on impulsive choice to issues of occupational safety and health. Impulsive choice is defined in terms of discounting, which is the tendency for the value of a commodity to decrease as a function of various parameters (e.g., having to wait or expend energy to receive…

Mesh refinement and numerical sensitivity analysis for parameter calibration of partial differential equations

NASA Astrophysics Data System (ADS)

Becker, Roland; Vexler, Boris

2005-06-01

We consider the calibration of parameters in physical models described by partial differential equations. This task is formulated as a constrained optimization problem with a cost functional of least squares type using information obtained from measurements. An important issue in the numerical solution of this type of problem is the control of the errors introduced, first, by discretization of the equations describing the physical model, and second, by measurement errors or other perturbations. Our strategy is as follows: we suppose that the user defines an interest functional I, which might depend on both the state variable and the parameters and which represents the goal of the computation. First, we propose an a posteriori error estimator which measures the error with respect to this functional. This error estimator is used in an adaptive algorithm to construct economic meshes by local mesh refinement. The proposed estimator requires the solution of an auxiliary linear equation. Second, we address the question of sensitivity. Applying similar techniques as before, we derive quantities which describe the influence of small changes in the measurements on the value of the interest functional. These numbers, which we call relative condition numbers, give additional information on the problem under consideration. They can be computed by means of the solution of the auxiliary problem determined before. Finally, we demonstrate our approach at hand of a parameter calibration problem for a model flow problem.

Multialternative drift-diffusion model predicts the relationship between visual fixations and choice in value-based decisions.

PubMed

Krajbich, Ian; Rangel, Antonio

2011-08-16

How do we make decisions when confronted with several alternatives (e.g., on a supermarket shelf)? Previous work has shown that accumulator models, such as the drift-diffusion model, can provide accurate descriptions of the psychometric data for binary value-based choices, and that the choice process is guided by visual attention. However, the computational processes used to make choices in more complicated situations involving three or more options are unknown. We propose a model of trinary value-based choice that generalizes what is known about binary choice, and test it using an eye-tracking experiment. We find that the model provides a quantitatively accurate description of the relationship between choice, reaction time, and visual fixation data using the same parameters that were estimated in previous work on binary choice. Our findings suggest that the brain uses similar computational processes to make binary and trinary choices.

Compositions and their application to the analysis of choice.

PubMed

Jensen, Greg

2014-07-01

Descriptions of steady-state patterns of choice allocation under concurrent schedules of reinforcement have long relied on the "generalized matching law" (Baum, 1974), a log-odds power function. Although a powerful model in some contexts, a series of conflicting empirical results have cast its generality in doubt. The relevance and analytic relevance of matching models can be greatly expanded by considering them in terms of compositions (Aitchison, 1986). A composition encodes a set of ratios (e.g., 5:3:2) as a vector with a constant sum, and this constraint (called closure) restricts the data to a nonstandard sample space. By exploiting this sample space, unbiased estimates of model parameters can be obtained to predict behavior given any number of choice alternatives. Additionally, the compositional analysis of choice provides tools that can accommodate both violations of scale invariance and unequal discriminability of stimuli signaling schedules of reinforcement. In order to demonstrate how choice data can be analyzed using the compositional approach, data from three previously published studies are reanalyzed. Additionally, new data is reported comparing matching behavior given four, six, and eight response alternatives. © Society for the Experimental Analysis of Behavior.

Stochastic Matching and the Voluntary Nature of Choice

PubMed Central

Neuringer, Allen; Jensen, Greg; Piff, Paul

2007-01-01

Attempts to characterize voluntary behavior have been ongoing for thousands of years. We provide experimental evidence that judgments of volition are based upon distributions of responses in relation to obtained rewards. Participants watched as responses, said to be made by “actors,” appeared on a computer screen. The participant's task was to estimate how well each actor represented the voluntary choices emitted by a real person. In actuality, all actors' responses were generated by algorithms based on Baum's (1979) generalized matching function. We systematically varied the exponent values (sensitivity parameter) of these algorithms: some actors matched response proportions to received reinforcer proportions, others overmatched (predominantly chose the highest-valued alternative), and yet others undermatched (chose relatively equally among the alternatives). In each of five experiments, we found that the matching actor's responses were judged most closely to approximate voluntary choice. We found also that judgments of high volition depended upon stochastic (or probabilistic) generation. Thus, stochastic responses that match reinforcer proportions best represent voluntary human choice. PMID:17725049

Dynamics in the Parameter Space of a Neuron Model

NASA Astrophysics Data System (ADS)

Paulo, C. Rech

2012-06-01

Some two-dimensional parameter-space diagrams are numerically obtained by considering the largest Lyapunov exponent for a four-dimensional thirteen-parameter Hindmarsh—Rose neuron model. Several different parameter planes are considered, and it is shown that depending on the combination of parameters, a typical scenario can be preserved: for some choice of two parameters, the parameter plane presents a comb-shaped chaotic region embedded in a large periodic region. It is also shown that there exist regions close to these comb-shaped chaotic regions, separated by the comb teeth, organizing themselves in period-adding bifurcation cascades.

Choosing Choice: School Choice in International Perspective.

ERIC Educational Resources Information Center

Plank, David N., Ed.; Sykes, Gary, Ed.

The chapters in this book originated as papers for a conference, School Choice and Educational Change, held in March 2000 at Michigan State University. An introductory chapter provides a comparative analysis of the lessons learned from international experience with school-choice policies, based on a review of case studies in several countries. The…

An Objective Rationale for the Choice of Regularisation Parameter with Application to Global Multiple-Frequency S-Wave Tomography

NASA Astrophysics Data System (ADS)

Zaroli, C.; Sambridge, M.; Leveque, J. J.; Debayle, E.; Nolet, G.

2014-12-01

In a linear ill-posed inverse problem, the regularisation parameter (damping) controls the balance between minimising both the residual data misfit and the model norm. Poor knowledge of data uncertainties often makes the selection of damping rather arbitrary. To go beyond that subjectivity, an objective rationale for the choice of damping is presented, which is based on the coherency of delay-time estimates in different frequency bands. Our method is tailored to the problem of global Multiple-Frequency Tomography, using a data set of 287078 S-wave delay-times measured in five frequency bands (10, 15, 22, 34, 51 s central periods). Whereas for each ray path the delay-time estimates should vary coherently from one period to the other, the noise most likely is not coherent. Thus, the lack of coherency of the information in different frequency bands is exploited, using an analogy with the cross-validation method, to identify models dominated by noise.In addition, a sharp change of behaviour of the model infinity-norm, as the damping becomes lower than a threshold value, is interpreted as the signature of data noise starting to significantly pollute at least one model component. Models with damping larger than this threshold are diagnosed as being constructed with poor data exploitation.Finally, a preferred model is selected from the remaining range of permitted model solutions. This choice is quasi-objective in terms of model interpretation, as the selected model shows a high degree of similarity with almost all other permitted models. The obtained tomographic model is displayed in mid lower-mantle (660-1910 km depth), and is shown to be mostly compatible with three other recent global shear-velocity models, while significant differences can be noticed. A wider application of the presented rationale should permit us to converge towards more objective seismic imaging of the Earth's mantle, using as much as possible of the relevant structural information in the data

Transformation Model Choice in Nonlinear Regression Analysis of Fluorescence-based Serial Dilution Assays

PubMed Central

Fong, Youyi; Yu, Xuesong

2016-01-01

Many modern serial dilution assays are based on fluorescence intensity (FI) readouts. We study optimal transformation model choice for fitting five parameter logistic curves (5PL) to FI-based serial dilution assay data. We first develop a generalized least squares-pseudolikelihood type algorithm for fitting heteroscedastic logistic models. Next we show that the 5PL and log 5PL functions can approximate each other well. We then compare four 5PL models with different choices of log transformation and variance modeling through a Monte Carlo study and real data. Our findings are that the optimal choice depends on the intended use of the fitted curves. PMID:27642502

Grading School Choice: Evaluating School Choice Programs by the Friedman Gold Standard. School Choice Issues in Depth

ERIC Educational Resources Information Center

Enlow, Robert C.

2008-01-01

In 2004, The Friedman Foundation for Educational Choice published a report titled "Grading Vouchers: Ranking America's School Choice Programs." Its purpose was to measure every existing school choice program against the gold standard set by Milton and Rose Friedman: that the most effective way to improve K-12 education and thus ensure a stable…

Metro passengers’ route choice model and its application considering perceived transfer threshold

PubMed Central

Jin, Fanglei; Zhang, Yongsheng; Liu, Shasha

2017-01-01

With the rapid development of the Metro network in China, the greatly increased route alternatives make passengers’ route choice behavior and passenger flow assignment more complicated, which presents challenges to the operation management. In this paper, a path sized logit model is adopted to analyze passengers’ route choice preferences considering such parameters as in-vehicle time, number of transfers, and transfer time. Moreover, the “perceived transfer threshold” is defined and included in the utility function to reflect the penalty difference caused by transfer time on passengers’ perceived utility under various numbers of transfers. Next, based on the revealed preference data collected in the Guangzhou Metro, the proposed model is calibrated. The appropriate perceived transfer threshold value and the route choice preferences are analyzed. Finally, the model is applied to a personalized route planning case to demonstrate the engineering practicability of route choice behavior analysis. The results show that the introduction of the perceived transfer threshold is helpful to improve the model’s explanatory abilities. In addition, personalized route planning based on route choice preferences can meet passengers’ diversified travel demands. PMID:28957376

Sequential and simultaneous choices: testing the diet selection and sequential choice models.

PubMed

Freidin, Esteban; Aw, Justine; Kacelnik, Alex

2009-03-01

We investigate simultaneous and sequential choices in starlings, using Charnov's Diet Choice Model (DCM) and Shapiro, Siller and Kacelnik's Sequential Choice Model (SCM) to integrate function and mechanism. During a training phase, starlings encountered one food-related option per trial (A, B or R) in random sequence and with equal probability. A and B delivered food rewards after programmed delays (shorter for A), while R ('rejection') moved directly to the next trial without reward. In this phase we measured latencies to respond. In a later, choice, phase, birds encountered the pairs A-B, A-R and B-R, the first implementing a simultaneous choice and the second and third sequential choices. The DCM predicts when R should be chosen to maximize intake rate, and SCM uses latencies of the training phase to predict choices between any pair of options in the choice phase. The predictions of both models coincided, and both successfully predicted the birds' preferences. The DCM does not deal with partial preferences, while the SCM does, and experimental results were strongly correlated to this model's predictions. We believe that the SCM may expose a very general mechanism of animal choice, and that its wider domain of success reflects the greater ecological significance of sequential over simultaneous choices.

A probabilistic approach for the estimation of earthquake source parameters from spectral inversion

NASA Astrophysics Data System (ADS)

Supino, M.; Festa, G.; Zollo, A.

2017-12-01

The amplitude spectrum of a seismic signal related to an earthquake source carries information about the size of the rupture, moment, stress and energy release. Furthermore, it can be used to characterize the Green's function of the medium crossed by the seismic waves. We describe the earthquake amplitude spectrum assuming a generalized Brune's (1970) source model, and direct P- and S-waves propagating in a layered velocity model, characterized by a frequency-independent Q attenuation factor. The observed displacement spectrum depends indeed on three source parameters, the seismic moment (through the low-frequency spectral level), the corner frequency (that is a proxy of the fault length) and the high-frequency decay parameter. These parameters are strongly correlated each other and with the quality factor Q; a rigorous estimation of the associated uncertainties and parameter resolution is thus needed to obtain reliable estimations.In this work, the uncertainties are characterized adopting a probabilistic approach for the parameter estimation. Assuming an L2-norm based misfit function, we perform a global exploration of the parameter space to find the absolute minimum of the cost function and then we explore the cost-function associated joint a-posteriori probability density function around such a minimum, to extract the correlation matrix of the parameters. The global exploration relies on building a Markov chain in the parameter space and on combining a deterministic minimization with a random exploration of the space (basin-hopping technique). The joint pdf is built from the misfit function using the maximum likelihood principle and assuming a Gaussian-like distribution of the parameters. It is then computed on a grid centered at the global minimum of the cost-function. The numerical integration of the pdf finally provides mean, variance and correlation matrix associated with the set of best-fit parameters describing the model. Synthetic tests are performed to

Dynamics of a neuron model in different two-dimensional parameter-spaces

NASA Astrophysics Data System (ADS)

Rech, Paulo C.

2011-03-01

We report some two-dimensional parameter-space diagrams numerically obtained for the multi-parameter Hindmarsh-Rose neuron model. Several different parameter planes are considered, and we show that regardless of the combination of parameters, a typical scenario is preserved: for all choice of two parameters, the parameter-space presents a comb-shaped chaotic region immersed in a large periodic region. We also show that exist regions close these chaotic region, separated by the comb teeth, organized themselves in period-adding bifurcation cascades.

A Priori and a Posteriori Dietary Patterns during Pregnancy and Gestational Weight Gain: The Generation R Study

PubMed Central

Tielemans, Myrte J.; Erler, Nicole S.; Leermakers, Elisabeth T. M.; van den Broek, Marion; Jaddoe, Vincent W. V.; Steegers, Eric A. P.; Kiefte-de Jong, Jessica C.; Franco, Oscar H.

2015-01-01

Abnormal gestational weight gain (GWG) is associated with adverse pregnancy outcomes. We examined whether dietary patterns are associated with GWG. Participants included 3374 pregnant women from a population-based cohort in the Netherlands. Dietary intake during pregnancy was assessed with food-frequency questionnaires. Three a posteriori-derived dietary patterns were identified using principal component analysis: a “Vegetable, oil and fish”, a “Nuts, high-fiber cereals and soy”, and a “Margarine, sugar and snacks” pattern. The a priori-defined dietary pattern was based on national dietary recommendations. Weight was repeatedly measured around 13, 20 and 30 weeks of pregnancy; pre-pregnancy and maximum weight were self-reported. Normal weight women with high adherence to the “Vegetable, oil and fish” pattern had higher early-pregnancy GWG than those with low adherence (43 g/week (95% CI 16; 69) for highest vs. lowest quartile (Q)). Adherence to the “Margarine, sugar and snacks” pattern was associated with a higher prevalence of excessive GWG (OR 1.45 (95% CI 1.06; 1.99) Q4 vs. Q1). Normal weight women with higher scores on the “Nuts, high-fiber cereals and soy” pattern had more moderate GWG than women with lower scores (−0.01 (95% CI −0.02; −0.00) per SD). The a priori-defined pattern was not associated with GWG. To conclude, specific dietary patterns may play a role in early pregnancy but are not consistently associated with GWG. PMID:26569303

Trajectory-adaptive route choice models : specification, choice set generation, and estimation.

DOT National Transportation Integrated Search

2013-03-01

The objective of the research is to investigate adaptive route choice behavior using individuallevel route choice data from GPS (Global Positioning System) observations in a real-life : network, where a traveler could revise the route choice based up...

Accuracy Estimation and Parameter Advising for Protein Multiple Sequence Alignment

PubMed Central

DeBlasio, Dan

2013-01-01

Abstract We develop a novel and general approach to estimating the accuracy of multiple sequence alignments without knowledge of a reference alignment, and use our approach to address a new task that we call parameter advising: the problem of choosing values for alignment scoring function parameters from a given set of choices to maximize the accuracy of a computed alignment. For protein alignments, we consider twelve independent features that contribute to a quality alignment. An accuracy estimator is learned that is a polynomial function of these features; its coefficients are determined by minimizing its error with respect to true accuracy using mathematical optimization. Compared to prior approaches for estimating accuracy, our new approach (a) introduces novel feature functions that measure nonlocal properties of an alignment yet are fast to evaluate, (b) considers more general classes of estimators beyond linear combinations of features, and (c) develops new regression formulations for learning an estimator from examples; in addition, for parameter advising, we (d) determine the optimal parameter set of a given cardinality, which specifies the best parameter values from which to choose. Our estimator, which we call Facet (for “feature-based accuracy estimator”), yields a parameter advisor that on the hardest benchmarks provides more than a 27% improvement in accuracy over the best default parameter choice, and for parameter advising significantly outperforms the best prior approaches to assessing alignment quality. PMID:23489379

[Clinical choice of a benzodiazepine].

PubMed

Villeneuve, A

1983-01-01

If the differential specific anxiolytic activity between various benzodiazepines remains controverted , the clinician nevertheless now possesses scientific data allowing him to make a more rational selection, in order to obtain a better overall efficacy, either for an anxiolytic or hypnotic action. In other respects, the concept of anxiety has evolved and given rise to distinctions that will need to be taken into account in the choice of the adequate psychotropic medication, either a benzodiazepine or another psychotropic drug. When a benzodiazepine must be prescribed, the main criteria involved in its choice need to be considered. As anxiolytic medication, besides a selective action on anxiety, the absence of cumbersome effect on psychomotor activity and vigilance, pharmacokinetics constitute an important factor that must be looked at. Although the classification of benzodiazepines according to their half-life is only an approximation, some overlapping being possible between the various groups, it proves nevertheless extremely useful with respect to the therapeutic goal considered and the various clinical parameters involved. Some other aspects must also be considered, for example the rebound phenomenon. Finally, the variability of individual responses to drug treatment must be remembered.

Uncertainty Quantification of GEOS-5 L-band Radiative Transfer Model Parameters Using Bayesian Inference and SMOS Observations

NASA Technical Reports Server (NTRS)

DeLannoy, Gabrielle J. M.; Reichle, Rolf H.; Vrugt, Jasper A.

2013-01-01

Uncertainties in L-band (1.4 GHz) radiative transfer modeling (RTM) affect the simulation of brightness temperatures (Tb) over land and the inversion of satellite-observed Tb into soil moisture retrievals. In particular, accurate estimates of the microwave soil roughness, vegetation opacity and scattering albedo for large-scale applications are difficult to obtain from field studies and often lack an uncertainty estimate. Here, a Markov Chain Monte Carlo (MCMC) simulation method is used to determine satellite-scale estimates of RTM parameters and their posterior uncertainty by minimizing the misfit between long-term averages and standard deviations of simulated and observed Tb at a range of incidence angles, at horizontal and vertical polarization, and for morning and evening overpasses. Tb simulations are generated with the Goddard Earth Observing System (GEOS-5) and confronted with Tb observations from the Soil Moisture Ocean Salinity (SMOS) mission. The MCMC algorithm suggests that the relative uncertainty of the RTM parameter estimates is typically less than 25 of the maximum a posteriori density (MAP) parameter value. Furthermore, the actual root-mean-square-differences in long-term Tb averages and standard deviations are found consistent with the respective estimated total simulation and observation error standard deviations of m3.1K and s2.4K. It is also shown that the MAP parameter values estimated through MCMC simulation are in close agreement with those obtained with Particle Swarm Optimization (PSO).

Choice Inconsistencies among the Elderly: Evidence from Plan Choice in the Medicare Part D Program: Reply

PubMed Central

ABALUCK, JASON

2017-01-01

We explore the in- and out- of sample robustness of tests for choice inconsistencies based on parameter restrictions in parametric models, focusing on tests proposed by Ketcham, Kuminoff and Powers (KKP). We argue that their non-parametric alternatives are inherently conservative with respect to detecting mistakes. We then show that our parametric model is robust to KKP’s suggested specification checks, and that comprehensive goodness of fit measures perform better with our model than the expected utility model. Finally, we explore the robustness of our 2011 results to alternative normative assumptions highlighting the role of brand fixed effects and unobservable characteristics. PMID:29170561

Choice and Desegregation.

ERIC Educational Resources Information Center

Bennett, David A.

This document comprises a report on the architectural elements of choice in the desegregation process, a review of the choice process based on Minnesota's experience, and a statement of implications for state policymakers. The following organizational principles of the choice process are discussed: (1) enrollment based on a "first come, first…

Parameter screening: the use of a dummy parameter to identify non-influential parameters in a global sensitivity analysis

NASA Astrophysics Data System (ADS)

Khorashadi Zadeh, Farkhondeh; Nossent, Jiri; van Griensven, Ann; Bauwens, Willy

2017-04-01

Parameter estimation is a major concern in hydrological modeling, which may limit the use of complex simulators with a large number of parameters. To support the selection of parameters to include in or exclude from the calibration process, Global Sensitivity Analysis (GSA) is widely applied in modeling practices. Based on the results of GSA, the influential and the non-influential parameters are identified (i.e. parameters screening). Nevertheless, the choice of the screening threshold below which parameters are considered non-influential is a critical issue, which has recently received more attention in GSA literature. In theory, the sensitivity index of a non-influential parameter has a value of zero. However, since numerical approximations, rather than analytical solutions, are utilized in GSA methods to calculate the sensitivity indices, small but non-zero indices may be obtained for the indices of non-influential parameters. In order to assess the threshold that identifies non-influential parameters in GSA methods, we propose to calculate the sensitivity index of a "dummy parameter". This dummy parameter has no influence on the model output, but will have a non-zero sensitivity index, representing the error due to the numerical approximation. Hence, the parameters whose indices are above the sensitivity index of the dummy parameter can be classified as influential, whereas the parameters whose indices are below this index are within the range of the numerical error and should be considered as non-influential. To demonstrated the effectiveness of the proposed "dummy parameter approach", 26 parameters of a Soil and Water Assessment Tool (SWAT) model are selected to be analyzed and screened, using the variance-based Sobol' and moment-independent PAWN methods. The sensitivity index of the dummy parameter is calculated from sampled data, without changing the model equations. Moreover, the calculation does not even require additional model evaluations for the Sobol

Choice of Tuning Parameters on 3D IC Engine Simulations Using G-Equation

DOE PAGES

Liu, Jinlong; Szybist, James; Dumitrescu, Cosmin

2018-04-03

3D CFD spark-ignition IC engine simulations are extremely complex for the regular user. Truly-predictive CFD simulations for the turbulent flame combustion that solve fully coupled transport/chemistry equations may require large computational capabilities unavailable to regular CFD users. A solution is to use a simpler phenomenological model such as the G-equation that decouples transport/chemistry result. Such simulation can still provide acceptable and faster results at the expense of predictive capabilities. While the G-equation is well understood within the experienced modeling community, the goal of this paper is to document some of them for a novice or less experienced CFD user whomore » may not be aware that phenomenological models of turbulent flame combustion usually require heavy tuning and calibration from the user to mimic experimental observations. This study used ANSYS® Forte, Version 17.2, and the built-in G-equation model, to investigate two tuning constants that influence flame propagation in 3D CFD SI engine simulations: the stretch factor coefficient, Cms and the flame development coefficient, Cm2. After identifying several Cm2-Cms pairs that matched experimental data at one operating conditions, simulation results showed that engine models that used different Cm2-Cms sets predicted similar combustion performance, when the spark timing, engine load, and engine speed were changed from the operating condition used to validate the CFD simulation. A dramatic shift was observed when engine speed was doubled, which suggested that the flame stretch coefficient, Cms, had a much larger influence at higher engine speeds compared to the flame development coefficient, Cm2. Therefore, the Cm2-Cms sets that predicted a higher turbulent flame under higher in-cylinder pressure and temperature increased the peak pressure and efficiency. This suggest that the choice of the Cm2-Cms will affect the G-equation-based simulation accuracy when engine speed increases

Choice of Tuning Parameters on 3D IC Engine Simulations Using G-Equation

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

Liu, Jinlong; Szybist, James; Dumitrescu, Cosmin

3D CFD spark-ignition IC engine simulations are extremely complex for the regular user. Truly-predictive CFD simulations for the turbulent flame combustion that solve fully coupled transport/chemistry equations may require large computational capabilities unavailable to regular CFD users. A solution is to use a simpler phenomenological model such as the G-equation that decouples transport/chemistry result. Such simulation can still provide acceptable and faster results at the expense of predictive capabilities. While the G-equation is well understood within the experienced modeling community, the goal of this paper is to document some of them for a novice or less experienced CFD user whomore » may not be aware that phenomenological models of turbulent flame combustion usually require heavy tuning and calibration from the user to mimic experimental observations. This study used ANSYS® Forte, Version 17.2, and the built-in G-equation model, to investigate two tuning constants that influence flame propagation in 3D CFD SI engine simulations: the stretch factor coefficient, Cms and the flame development coefficient, Cm2. After identifying several Cm2-Cms pairs that matched experimental data at one operating conditions, simulation results showed that engine models that used different Cm2-Cms sets predicted similar combustion performance, when the spark timing, engine load, and engine speed were changed from the operating condition used to validate the CFD simulation. A dramatic shift was observed when engine speed was doubled, which suggested that the flame stretch coefficient, Cms, had a much larger influence at higher engine speeds compared to the flame development coefficient, Cm2. Therefore, the Cm2-Cms sets that predicted a higher turbulent flame under higher in-cylinder pressure and temperature increased the peak pressure and efficiency. This suggest that the choice of the Cm2-Cms will affect the G-equation-based simulation accuracy when engine speed increases

Constructing food choice decisions.

PubMed

Sobal, Jeffery; Bisogni, Carole A

2009-12-01

Food choice decisions are frequent, multifaceted, situational, dynamic, and complex and lead to food behaviors where people acquire, prepare, serve, give away, store, eat, and clean up. Many disciplines and fields examine decision making. Several classes of theories are applicable to food decision making, including social behavior, social facts, and social definition perspectives. Each offers some insights but also makes limiting assumptions that prevent fully explaining food choice decisions. We used constructionist social definition perspectives to inductively develop a food choice process model that organizes a broad scope of factors and dynamics involved in food behaviors. This food choice process model includes (1) life course events and experiences that establish a food choice trajectory through transitions, turning points, timing, and contexts; (2) influences on food choices that include cultural ideals, personal factors, resources, social factors, and present contexts; and (3) a personal system that develops food choice values, negotiates and balances values, classifies foods and situations, and forms/revises food choice strategies, scripts, and routines. The parts of the model dynamically interact to make food choice decisions leading to food behaviors. No single theory can fully explain decision making in food behavior. Multiple perspectives are needed, including constructionist thinking.

Predictors of science, technology, engineering, and mathematics choice options: A meta-analytic path analysis of the social-cognitive choice model by gender and race/ethnicity.

PubMed

Lent, Robert W; Sheu, Hung-Bin; Miller, Matthew J; Cusick, Megan E; Penn, Lee T; Truong, Nancy N

2018-01-01

We tested the interest and choice portion of social-cognitive career theory (SCCT; Lent, Brown, & Hackett, 1994) in the context of science, technology, engineering, and mathematics (STEM) domains. Data from 143 studies (including 196 independent samples) conducted over a 30-year period (1983 through 2013) were subjected to meta-analytic path analyses. The interest/choice model was found to fit the data well over all samples as well as within samples composed primarily of women and men and racial/ethnic minority and majority persons. The model also accounted for large portions of the variance in interests and choice goals within each path analysis. Despite the general predictive utility of SCCT across gender and racial/ethnic groups, we did find that several parameter estimates differed by group. We present both the group similarities and differences and consider their implications for future research, intervention, and theory refinement. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Total protein measurement in canine cerebrospinal fluid: agreement between a turbidimetric assay and 2 dye-binding methods and determination of reference intervals using an indirect a posteriori method.

PubMed

Riond, B; Steffen, F; Schmied, O; Hofmann-Lehmann, R; Lutz, H

2014-03-01

In veterinary clinical laboratories, qualitative tests for total protein measurement in canine cerebrospinal fluid (CSF) have been replaced by quantitative methods, which can be divided into dye-binding assays and turbidimetric methods. There is a lack of validation data and reference intervals (RIs) for these assays. The aim of the present study was to assess agreement between the turbidimetric benzethonium chloride method and 2 dye-binding methods (Pyrogallol Red-Molybdate method [PRM], Coomassie Brilliant Blue [CBB] technique) for measurement of total protein concentration in canine CSF. Furthermore, RIs were determined for all 3 methods using an indirect a posteriori method. For assay comparison, a total of 118 canine CSF specimens were analyzed. For RIs calculation, clinical records of 401 canine patients with normal CSF analysis were studied and classified according to their final diagnosis in pathologic and nonpathologic values. The turbidimetric assay showed excellent agreement with the PRM assay (mean bias 0.003 g/L [-0.26-0.27]). The CBB method generally showed higher total protein values than the turbidimetric assay and the PRM assay (mean bias -0.14 g/L for turbidimetric and PRM assay). From 90 of 401 canine patients, nonparametric reference intervals (2.5%, 97.5% quantile) were calculated (turbidimetric assay and PRM method: 0.08-0.35 g/L (90% CI: 0.07-0.08/0.33-0.39); CBB method: 0.17-0.55 g/L (90% CI: 0.16-0.18/0.52-0.61). Total protein concentration in canine CSF specimens remained stable for up to 6 months of storage at -80°C. Due to variations among methods, RIs for total protein concentration in canine CSF have to be calculated for each method. The a posteriori method of RIs calculation described here should encourage other veterinary laboratories to establish RIs that are laboratory-specific. ©2014 American Society for Veterinary Clinical Pathology and European Society for Veterinary Clinical Pathology.

Consumer perception of dry-cured sheep meat products: Influence of process parameters under different evoked contexts.

PubMed

de Andrade, Juliana Cunha; Nalério, Elen Silveira; Giongo, Citieli; de Barcellos, Marcia Dutra; Ares, Gastón; Deliza, Rosires

2017-08-01

The development of high-quality air-dried cured sheep meat products adapted to meet consumer demands represent an interesting option to add value to the meat of adult animals. The present study aimed to evaluate the influence of process parameters on consumer choice of two products from sheep meat under different evoked contexts, considering product concepts. A total of 375 Brazilian participants completed a choice-based conjoint task with three 2-level variables for each product: maturation time, smoking, and sodium reduction for dry-cured sheep ham, and natural antioxidant, smoking, and sodium reduction for sheep meat coppa. A between-subjects experimental design was used to evaluate the influence of consumption context on consumer choices. All the process parameters significantly influenced consumer choice. However, their relative importance was affected by evoked context. Copyright © 2017. Published by Elsevier Ltd.

Effort, success, and nonuse determine arm choice

PubMed Central

Xiao, Yupeng; Kim, Sujin; Yoshioka, Toshinori; Gordon, James; Osu, Rieko

2015-01-01

How do humans choose one arm or the other to reach single targets in front of the body? Current theories of reward-driven decisionmaking predict that choice results from a comparison of “action values,” which are the expected rewards for possible actions in a given state. In addition, current theories of motor control predict that in planning arm movements, humans minimize an expected motor cost that balances motor effort and endpoint accuracy. Here, we test the hypotheses that arm choice is determined by comparison of action values comprising expected effort and expected task success for each arm, as well as a handedness bias. Right-handed subjects, in either a large or small target condition, were first instructed to use each hand in turn to shoot through an array of targets and then to choose either hand to shoot through the same targets. Effort was estimated via inverse kinematics and dynamics. A mixed-effects logistic-regression analysis showed that, as predicted, both expected effort and expected success predicted choice, as did arm use in the preceding trial. Finally, individual parameter estimation showed that the handedness bias correlated with mean difference between right- and left-arm success, leading to overall lower use of the left arm. We discuss our results in light of arm nonuse in individuals' poststroke. PMID:25948869

A Systematic Approach for Model-Based Aircraft Engine Performance Estimation

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Garg, Sanjay

2010-01-01

A requirement for effective aircraft engine performance estimation is the ability to account for engine degradation, generally described in terms of unmeasurable health parameters such as efficiencies and flow capacities related to each major engine module. This paper presents a linear point design methodology for minimizing the degradation-induced error in model-based aircraft engine performance estimation applications. The technique specifically focuses on the underdetermined estimation problem, where there are more unknown health parameters than available sensor measurements. A condition for Kalman filter-based estimation is that the number of health parameters estimated cannot exceed the number of sensed measurements. In this paper, the estimated health parameter vector will be replaced by a reduced order tuner vector whose dimension is equivalent to the sensed measurement vector. The reduced order tuner vector is systematically selected to minimize the theoretical mean squared estimation error of a maximum a posteriori estimator formulation. This paper derives theoretical estimation errors at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the estimation accuracy achieved through conventional maximum a posteriori and Kalman filter estimation approaches. Maximum a posteriori estimation results demonstrate that reduced order tuning parameter vectors can be found that approximate the accuracy of estimating all health parameters directly. Kalman filter estimation results based on the same reduced order tuning parameter vectors demonstrate that significantly improved estimation accuracy can be achieved over the conventional approach of selecting a subset of health parameters to serve as the tuner vector. However, additional development is necessary to fully extend the methodology to Kalman filter

Choice experiments

Treesearch

Thomas P Holmes; Wiktor L Adamawicz; Fredrik Carlsson

2017-01-01

There has been an explosion of interest during the past two decades in a class of nonmarket stated-preference valuation methods known as choice experiments. The overall objective of a choice experiment is to estimate economic values for characteristics (or attributes) of an environmental good that is the subject of policy analysis, where...

User Choice.

ERIC Educational Resources Information Center

Smith, Joy Selby

In vocational education and training (VET), user choice is a means of achieving a more client-responsive training system by allowing clients to have greater choice over how their training needs are met. Funding arrangements linked in some direct way to the expressed demands of individual clients are essential for effective operation of a user…

The malleability of intertemporal choice

PubMed Central

Lempert, Karolina M.; Phelps, Elizabeth A.

2015-01-01

Intertemporal choices are ubiquitous: people often have to choose between outcomes realized at different times. Although it is generally believed that people have stable tendencies toward being impulsive or patient, an emerging body of evidence indicates that intertemporal choice is malleable and can be profoundly influenced by context. How the choice is framed, or the state of the decision-maker at the time of choice, can induce a shift in preference. Framing effects are underpinned by: allocation of attention to choice attributes, reference-dependence and time construal. Incidental affective states and prospection also influence intertemporal choice. We advocate that intertemporal choice models account for these context effects, and encourage the use of this knowledge to nudge people toward making more advantageous choices. PMID:26483153

The effect of integration of non-cognitive parameters on medical students' characteristics and their intended career choices.

PubMed

Halpern, Naama; Bentov-Gofrit, Daphne; Matot, Idit; Abramowitz, Moshe Z

2011-08-01

A new approach for assessing non-cognitive attributes in medical school candidates was developed and implemented at the Hebrew University Medical School. The non-cognitive tests included a biographical questionnaire, a questionnaire raising theoretical dilemmas and multiple mini-interviews. To evaluate the effects of the change in the admission process on students' demographics and future career choices. A questionnaire including questions on students' background and future residency preferences was administered to first-year students accepted to medical school by the new admission system. Results were compared with previous information collected from students admitted through the old admission process. Students accepted by the new process were significantly older (22.49 vs. 21.54, P < 0.001), and more had attended other academic studies before medical school, considered other professions besides medicine, and majored in humanities combined with sciences in high school. Significantly more students from small communities were admitted by the new system. Differences were found in preferences for future residencies; compared with the old admission process (N = 41), students admitted by the new system (N = 85) had a more positive attitude towards a career in obstetrics/gynecology (41% vs. 22%, P < 0.001) and hematology/oncology (11.7% vs. 4.8%, P < 0.001), while the popularity of surgery and pediatrics had decreased (34.5% vs. 61%, P < 0.001 and 68.7% vs. 82.5%, P < 0.001 respectively). Assessment of non-cognitive parameters as part of the admission criteria to medical school was associated with an older and more heterogenic group of students and different preferences for future residency. Whether these preferences in first-year students persist through medical school is a question for further research.

GluN2B in corticostriatal circuits governs choice learning and choice shifting

PubMed Central

Brigman, Jonathan L.; Daut, Rachel; Wright, Tara; Gunduz-Cinar, Ozge; Graybeal, Carolyn; Davis, Margaret I.; Jiang, Zhihong; Saksida, Lisa; Jinde, Seiichiro; Pease, Matthew; Bussey, Timothy J.; Lovinger, David M.; Nakazawa, Kazu; Holmes, Andrew

2013-01-01

A choice that reliably produces a preferred outcome can be automated to liberate cognitive resources for other tasks. Should an outcome become less desirable, behavior must adapt in parallel or become perseverative. Corticostriatal systems are known to mediate choice learning and flexibility, but the molecular mechanisms subserving the instantiation of these processes are not well understood. We integrated mouse behavioral, immunocytochemical, in vivo electrophysiological, genetic, and pharmacological approaches to study choice. We found that the dorsal striatum (DS) was increasingly activated with choice learning, whereas reversal of learned choice engaged prefrontal regions. In vivo, DS neurons showed activity associated with reward anticipation and receipt that emerged with learning and relearning. Corticostriatal or striatal GluN2B gene deletion, or DS-restricted GluN2B antagonism, impaired choice learning, whereas cortical GluN2B deletion or OFC GluN2B antagonism impaired shifting. Our convergent data demonstrate how corticostriatal GluN2B circuits govern the ability to learn and shift choice behavior. PMID:23831965

A simple computational algorithm of model-based choice preference.

PubMed

Toyama, Asako; Katahira, Kentaro; Ohira, Hideki

2017-08-01

A broadly used computational framework posits that two learning systems operate in parallel during the learning of choice preferences-namely, the model-free and model-based reinforcement-learning systems. In this study, we examined another possibility, through which model-free learning is the basic system and model-based information is its modulator. Accordingly, we proposed several modified versions of a temporal-difference learning model to explain the choice-learning process. Using the two-stage decision task developed by Daw, Gershman, Seymour, Dayan, and Dolan (2011), we compared their original computational model, which assumes a parallel learning process, and our proposed models, which assume a sequential learning process. Choice data from 23 participants showed a better fit with the proposed models. More specifically, the proposed eligibility adjustment model, which assumes that the environmental model can weight the degree of the eligibility trace, can explain choices better under both model-free and model-based controls and has a simpler computational algorithm than the original model. In addition, the forgetting learning model and its variation, which assume changes in the values of unchosen actions, substantially improved the fits to the data. Overall, we show that a hybrid computational model best fits the data. The parameters used in this model succeed in capturing individual tendencies with respect to both model use in learning and exploration behavior. This computational model provides novel insights into learning with interacting model-free and model-based components.

Models for estimating photosynthesis parameters from in situ production profiles

NASA Astrophysics Data System (ADS)

Kovač, Žarko; Platt, Trevor; Sathyendranath, Shubha; Antunović, Suzana

2017-12-01

The rate of carbon assimilation in phytoplankton primary production models is mathematically prescribed with photosynthesis irradiance functions, which convert a light flux (energy) into a material flux (carbon). Information on this rate is contained in photosynthesis parameters: the initial slope and the assimilation number. The exactness of parameter values is crucial for precise calculation of primary production. Here we use a model of the daily production profile based on a suite of photosynthesis irradiance functions and extract photosynthesis parameters from in situ measured daily production profiles at the Hawaii Ocean Time-series station Aloha. For each function we recover parameter values, establish parameter distributions and quantify model skill. We observe that the choice of the photosynthesis irradiance function to estimate the photosynthesis parameters affects the magnitudes of parameter values as recovered from in situ profiles. We also tackle the problem of parameter exchange amongst the models and the effect it has on model performance. All models displayed little or no bias prior to parameter exchange, but significant bias following parameter exchange. The best model performance resulted from using optimal parameter values. Model formulation was extended further by accounting for spectral effects and deriving a spectral analytical solution for the daily production profile. The daily production profile was also formulated with time dependent growing biomass governed by a growth equation. The work on parameter recovery was further extended by exploring how to extract photosynthesis parameters from information on watercolumn production. It was demonstrated how to estimate parameter values based on a linearization of the full analytical solution for normalized watercolumn production and from the solution itself, without linearization. The paper complements previous works on photosynthesis irradiance models by analysing the skill and consistency of

Development and conceptual validation of a questionnaire to help contraceptive choice: CHLOE (Contraception: HeLping for wOmen's choicE).

PubMed

Jamin, Christian Georges; Häusler, Gunther; Lobo Abascal, Paloma; Fiala, Christian; Lete Lasa, Luis Ignacio; Nappi, Rossella Elena; Micheletti, Marie-Christine; Fernández-Dorado, Ana; Pintiaux, Axelle; Chabbert-Buffet, Natalie

2017-08-01

The aim of this research was to develop a questionnaire to facilitate choice of the most appropriate contraceptive method for individual women. A literature review was conducted to identify key aspects influencing contraceptive choice and inform development of a questionnaire for online completion. Questionnaire development was overseen by a steering committee consisting of eight gynaecologists from across Europe. The initial draft underwent conceptual validation through cognitive debriefing interviews with six native English-speaking women. A qualitative content analysis was conducted to accurately identify potential issues and areas for questionnaire improvement. A revised version of the questionnaire then underwent face-to-face and online evaluation by 115 international gynaecologists/obstetricians with expertise in contraception, prior to development of a final version. The final conceptually validated Contraception: HeLping for wOmen's choicE (CHLOE) questionnaire takes ≤10 min to complete and includes three sections to elicit general information about the individual, the health conditions that might influence contraceptive choice, and the woman's needs and preferences that might influence contraceptive choice. The questionnaire captures the core aspects of personalisation, efficacy and safety, identified as key attributes influencing contraceptive choice, and consists of 24 closed-ended questions for online completion prior to a health care provider (HCP) consultation. The HCP receives a summary of the responses. The CHLOE questionnaire has been developed to help women choose the contraception that best suits their needs and situation while optimising the HCP's time.

Decoupled choice-driven and stimulus-related activity in parietal neurons may be misrepresented by choice probabilities.

PubMed

Zaidel, Adam; DeAngelis, Gregory C; Angelaki, Dora E

2017-09-28

Trial-by-trial correlations between neural responses and choices (choice probabilities) are often interpreted to reflect a causal contribution of neurons to task performance. However, choice probabilities may arise from top-down, rather than bottom-up, signals. We isolated distinct sensory and decision contributions to single-unit activity recorded from the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of monkeys during perception of self-motion. Superficially, neurons in both areas show similar tuning curves during task performance. However, tuning in MSTd neurons primarily reflects sensory inputs, whereas choice-related signals dominate tuning in VIP neurons. Importantly, the choice-related activity of VIP neurons is not predictable from their stimulus tuning, and these factors are often confounded in choice probability measurements. This finding was confirmed in a subset of neurons for which stimulus tuning was measured during passive fixation. Our findings reveal decoupled stimulus and choice signals in the VIP area, and challenge our understanding of choice signals in the brain.Choice-related signals in neuronal activity may reflect bottom-up sensory processes, top-down decision-related influences, or a combination of the two. Here the authors report that choice-related activity in VIP neurons is not predictable from their stimulus tuning, and that dominant choice signals can bias the standard metric of choice preference (choice probability).

A fair range of choice: justifying maximum patient choice in the British National Health Service.

PubMed

Wilmot, Stephen

2007-06-01

In this paper I put forward an ethical argument for the provision of extensive patient choice by the British National Health Service. I base this argument on traditional liberal rights to freedom of choice, on a welfare right to health care, and on a view of health as values-based. I argue that choice, to be ethically sustainable on this basis, must be values-based and rational. I also consider whether the British taxpayer may be persuadable with regard to the moral acceptability of patient choice, making use of Rawls' theory of political liberalism in this context. I identify issues that present problems in terms of public acceptance of choice, and also identify a boundary issue with regard to public health choices as against individual choices.

[Significance of motivation balance for a choice of dog's behavior under conditions of environmental uncertainty].

PubMed

Chilingarian, L I; Grigor'ian, G A

2007-01-01

Two experimental models with a choice between two reinforcements were used for assessment of individual typological features of dogs. In the first model dogs were given the choice of homogeneous food reinforcements: between less valuable constantly delivered reinforcement and more valuable reinforcement but delivered with low probabilities. In the second model the dogs had the choice of heterogeneous reinforcements: between performing alimentary and defensive reactions. Under conditions of rise of uncertainty owing to a decrease in probability of getting the valuable food, two dogs continued to prefer the valuable reinforcement, while the third animal gradually shifted its behavior from the choice of a highly valuable but infrequent reward to a less valuable but easily achieved reinforcement. Under condition of choice between the valuable food reinforcement and avoidance of electrocutaneous stimulation, the first two dogs preferred food, whereas the third animal which had been previously oriented to the choice of the low-valuable constant reinforcement, steadily preferred the avoidance behavior. The data obtained are consistent with the hypothesis according to which the individual typological characteristics of animals's (human's) behavior substantially depend on two parameters: extent of environmental uncertainty and subjective features of reinforcement assessment.

MicroCT parameters for multimaterial elements assessment

NASA Astrophysics Data System (ADS)

de Araújo, Olga M. O.; Silva Bastos, Jaqueline; Machado, Alessandra S.; dos Santos, Thaís M. P.; Ferreira, Cintia G.; Rosifini Alves Claro, Ana Paula; Lopes, Ricardo T.

2018-03-01

Microtomography is a non-destructive testing technique for quantitative and qualitative analysis. The investigation of multimaterial elements with great difference of density can result in artifacts that degrade image quality depending on combination of additional filter. The aim of this study is the selection of parameters most appropriate for analysis of bone tissue with metallic implant. The results show the simulation with MCNPX code for the distribution of energy without additional filter, with use of aluminum, copper and brass filters and their respective reconstructed images showing the importance of the choice of these parameters in image acquisition process on computed microtomography.

Privatization and Educational Choice.

ERIC Educational Resources Information Center

Lieberman, Myron

This book describes how and why educational choice movements will affect public education. It uses a public-choice approach to argue that both the supporters and opponents of private and school choice have failed to address several critical issues. Following an introductory chapter, chapter 2 is devoted to the rationale for contracting out…

Controlled-Choice Desegregation Plans: Not Enough Choice, Too Much Control?

ERIC Educational Resources Information Center

Rossell, Christine H.

1995-01-01

Examines whether controlled choice is a superior desegregation tool for urban schools. A study of 20 school districts with minority populations above 30% revealed controlled choice to be as unpopular as mandatory reassignments, to produce greater white flight than magnet-voluntary plans, and to offer less interracial exposure than do voluntary…

Determinants of choice of delivery place: Testing rational choice theory and habitus theory.

PubMed

Broda, Anja; Krüger, Juliane; Schinke, Stephanie; Weber, Andreas

2018-05-07

The current study uses two antipodal social science theories, the rational choice theory and the habitus theory, and applies these to describe how women choose between intraclinical (i.e., hospital-run birth clinics) and extraclinical (i.e., midwife-led birth centres or home births) delivery places. Data were collected in a cross-sectional questionnaire-based survey among 189 women. A list of 22 determinants, conceptualized to capture the two theoretical concepts, were rated on a 7-point Likert scale with 1 = unimportant to 7 = very important. The analytic method was structural equation modelling. A model was built, in which the rational choice theory and the habitus theory as latent variables predicted the choice of delivery place. With regards to the choice of delivery place, 89.3% of the women wanted an intraclinical and 10.7% an extraclinical delivery place at the time of their last child's birth. Significant differences between women with a choice of an intraclinical or extraclinical delivery place were found for 14 of the 22 determinants. In the structural equation model, rational choice theory determinants predicted a choice of intraclinical delivery and habitus theory determinants predicted a choice of extraclinical delivery. The two theories had diametrically opposed effects on the choice of delivery place. Women are more likely to decide on intraclinical delivery when arguments such as high medical standards, positive evaluations, or good advanced information are rated important. In contrast, women are more likely to decide on extraclinical delivery when factors such as family atmosphere during birth, friendliness of health care professionals, or consideration of the woman's interests are deemed important. A practical implication of our study is that intraclinical deliveries may be promoted by providing comprehensive information, data and facts on various delivery-related issues, while extraclinical deliveries may be fostered by healthcare

Impact of Retirement Choices of Early Career Marines: A Choice Analysis Model

DTIC Science & Technology

2013-03-01

CHOICES OF EARLY CAREER MARINES: A CHOICE ANALYSIS MODEL by André G. La Taste Aaron Masaitis March 2013 Thesis Advisor: Michael Dixon... ANALYSIS MODEL 5. FUNDING NUMBERS 6. AUTHOR(S) André G. La Taste, Aaron Masaitis 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate...system. The research will be conducted using a discrete choice analysis methodology that is often used to differentiate factors that lead to

Parental Voucher Enrollment Decisions: Choice within Choice in New Orleans

ERIC Educational Resources Information Center

Beabout, Brian R.; Cambre, Belinda M.

2013-01-01

Set in the context of a choice-saturated public school system, this study examines the school choice process of low-income parents who participated in Louisiana's 2008 voucher program. Based on semistructured interviews with 16 parents at 1 Catholic school, we report that spirituality, small class and school size, character/values, familiarity,…

Classical nucleation theory of homogeneous freezing of water: thermodynamic and kinetic parameters.

PubMed

Ickes, Luisa; Welti, André; Hoose, Corinna; Lohmann, Ulrike

2015-02-28

The probability of homogeneous ice nucleation under a set of ambient conditions can be described by nucleation rates using the theoretical framework of Classical Nucleation Theory (CNT). This framework consists of kinetic and thermodynamic parameters, of which three are not well-defined (namely the interfacial tension between ice and water, the activation energy and the prefactor), so that any CNT-based parameterization of homogeneous ice formation is less well-constrained than desired for modeling applications. Different approaches to estimate the thermodynamic and kinetic parameters of CNT are reviewed in this paper and the sensitivity of the calculated nucleation rate to the choice of parameters is investigated. We show that nucleation rates are very sensitive to this choice. The sensitivity is governed by one parameter - the interfacial tension between ice and water, which determines the energetic barrier of the nucleation process. The calculated nucleation rate can differ by more than 25 orders of magnitude depending on the choice of parameterization for this parameter. The second most important parameter is the activation energy of the nucleation process. It can lead to a variation of 16 orders of magnitude. By estimating the nucleation rate from a collection of droplet freezing experiments from the literature, the dependence of these two parameters on temperature is narrowed down. It can be seen that the temperature behavior of these two parameters assumed in the literature does not match with the predicted nucleation rates from the fit in most cases. Moreover a comparison of all possible combinations of theoretical parameterizations of the dominant two free parameters shows that one combination fits the fitted nucleation rates best, which is a description of the interfacial tension coming from a molecular model [Reinhardt and Doye, J. Chem. Phys., 2013, 139, 096102] in combination with the activation energy derived from self-diffusion measurements [Zobrist

The Choice Controversy.

ERIC Educational Resources Information Center

Cookson, Peter W., Jr., Ed.

Issues in school choice--constitutionality, feasibility, equity, and educational productivity--are examined in this book. The controversy requires an ongoing analysis of the origins of the school-choice movement, the kinds of plans proposed and implemented, their educational and social consequences, and the philosophical assumptions underlying the…

Gaussian mass optimization for kernel PCA parameters

NASA Astrophysics Data System (ADS)

Liu, Yong; Wang, Zulin

2011-10-01

This paper proposes a novel kernel parameter optimization method based on Gaussian mass, which aims to overcome the current brute force parameter optimization method in a heuristic way. Generally speaking, the choice of kernel parameter should be tightly related to the target objects while the variance between the samples, the most commonly used kernel parameter, doesn't possess much features of the target, which gives birth to Gaussian mass. Gaussian mass defined in this paper has the property of the invariance of rotation and translation and is capable of depicting the edge, topology and shape information. Simulation results show that Gaussian mass leads a promising heuristic optimization boost up for kernel method. In MNIST handwriting database, the recognition rate improves by 1.6% compared with common kernel method without Gaussian mass optimization. Several promising other directions which Gaussian mass might help are also proposed at the end of the paper.

The Parameter of Aspect in Second Language Acquisition.

ERIC Educational Resources Information Center

Slabakova, Roumyana

1999-01-01

Presents a detailed study of the second-language (L2) acquisition of English aspect by native speakers of Slavic languages. Results bring new evidence to bear on the theoretical choice between direct access to the L2 value or starting out the process of acquisition with the first-language value of a parameter, supporting the latter view.…

Paradoxical choice in rats: Subjective valuation and mechanism of choice.

PubMed

Ojeda, Andrés; Murphy, Robin A; Kacelnik, Alex

2018-07-01

Decision-makers benefit from information only when they can use it to guide behavior. However, recent experiments found that pigeons and starlings value information that they cannot use. Here we show that this paradox is also present in rats, and explore the underlying decision process. Subjects chose between two options that delivered food probabilistically after a fixed delay. In one option ("info"), outcomes (food/no-food) were signaled immediately after choice, whereas in the alternative ("non-info") the outcome was uncertain until the delay lapsed. Rats sacrificed up to 20% potential rewards by preferring the info option, but reversed preference when the cost was 60%. This reversal contrasts with the results found with pigeons and starlings and may reflect species' differences worth of further investigation. Results are consistent with predictions of the Sequential Choice Model (SCM), that proposes that choices are driven by the mechanisms that control action in sequential encounters. As expected from the SCM, latencies to respond in single-option trials predicted preferences in choice trials, and latencies in choice trials were the same or shorter than in single-option trials. We argue that the congruence of results in distant vertebrates probably reflects evolved adaptations to shared fundamental challenges in nature, and that the apparently paradoxical overvaluing of information is not sub-optimal as has been claimed, even though its functional significance is not yet understood. Copyright © 2018 Elsevier B.V. All rights reserved.

Relatively Recursive Rational Choice.

DTIC Science & Technology

1981-11-01

for the decision procedure of recursively representable rational choice. Alternatively phrased, we wish to inquire into its degrees of unsolvability. We...may first make the observation that there are three classic notions of reducibility of decision procedures for subsets of the natural numbers... rational choice function defined as an effectively computable represent- ation of Richter’s [1971] concept of rational choice, attains by means of an

Retirement Choice 2015

DTIC Science & Technology

2015-11-01

and Aline Quester November 2015 Copyright © 2015 CNA This document contains the best opinion of CNA at the time of issue. It does...RetirementChoiceCalculator.aspx. 3 The original paper was by Aline O. Quester and Lewis G. Lee, The Retirement Choice: FY 2006, CNA Research

Cryptanalysis of SFLASH with Slightly Modified Parameters

NASA Astrophysics Data System (ADS)

Dubois, Vivien; Fouque, Pierre-Alain; Stern, Jacques

SFLASH is a signature scheme which belongs to a family of multivariate schemes proposed by Patarin et al. in 1998 [9]. The SFLASH scheme itself has been designed in 2001 [8] and has been selected in 2003 by the NESSIE European Consortium [6] as the best known solution for implementation on low cost smart cards. In this paper, we show that slight modifications of the parameters of SFLASH within the general family initially proposed renders the scheme insecure. The attack uses simple linear algebra, and allows to forge a signature for an arbitrary message in a question of minutes for practical parameters, using only the public key. Although SFLASH itself is not amenable to our attack, it is worrying to observe that no rationale was ever offered for this "lucky" choice of parameters.

Fitting observed and theoretical choices - women's choices about prenatal diagnosis of Down syndrome.

PubMed

Seror, Valerie

2008-05-01

Choices regarding prenatal diagnosis of Down syndrome - the most frequent chromosomal defect - are particularly relevant to decision analysis, since women's decisions are based on the assessment of their risk of carrying a child with Down syndrome, and involve tradeoffs (giving birth to an affected child vs procedure-related miscarriage). The aim of this study, based on face-to-face interviews with 78 women aged 25-35 with prior experience of pregnancy, was to compare the women' expressed choices towards prenatal diagnosis with those derived from theoretical models of choice (expected utility theory, rank-dependent theory, and cumulative prospect theory). The main finding obtained in this study was that the cumulative prospect model fitted the observed choices best: both subjective transformation of probabilities and loss aversion, which are basic features of the cumulative prospect model, have to be taken into account to make the observed choices consistent with the theoretical ones.

PEER REVIEW FOR THE CONSUMER VEHICLE CHOICE ...

EPA Pesticide Factsheets

The U.S. Environmental Protection Agency’s (EPA) Office of Transportation and Air Quality (OTAQ) has recently sponsored the development of a Consumer Vehicle Choice Model (CVCM) by the Oak Ridge National Laboratory (ORNL). The specification by OTAQ to ORNL for consumer choice model development was to develop a Nested Multinomial Logit (NMNL) or other appropriate model capable of estimating the consumer surplus impacts and the sales mix effects of greenhouse gas (GHG) emission standards. The CVCM will use output from the EPA’s Optimization Model for reducing Emissions of Greenhouse gases from Automobiles (OMEGA), including changes in retail price equivalents, changes in fuel economy, and changes in emissions, to estimate these impacts. In addition, the CVCM will accept approximately 60 vehicle types, with the flexibility to function with fewer or more vehicle types, and will use a 15 year planning horizon, matching the OMEGA parameters. It will be calibrated to baseline sales projection data provided by the EPA and will include a buy/no-buy option to simulate the possibility that consumers will choose to keep their old vehicle or to buy a used vehicle. To support EPA's future assessment of potential light duty greenhouse gas standards

Systems for monitoring and digitally recording water-quality parameters

USGS Publications Warehouse

Smoot, George F.; Blakey, James F.

1966-01-01

Digital recording of water-quality parameters is a link in the automated data collection and processing system of the U.S. Geological Survey. The monitoring and digital recording systems adopted by the Geological Survey, while punching all measurements on a standard paper tape, provide a choice of compatible components to construct a system to meet specific physical problems and data needs. As many as 10 parameters can be recorded by an Instrument, with the only limiting criterion being that measurements are expressed as electrical signals.

Eye Movements in Risky Choice

PubMed Central

Hermens, Frouke; Matthews, William J.

2015-01-01

Abstract We asked participants to make simple risky choices while we recorded their eye movements. We built a complete statistical model of the eye movements and found very little systematic variation in eye movements over the time course of a choice or across the different choices. The only exceptions were finding more (of the same) eye movements when choice options were similar, and an emerging gaze bias in which people looked more at the gamble they ultimately chose. These findings are inconsistent with prospect theory, the priority heuristic, or decision field theory. However, the eye movements made during a choice have a large relationship with the final choice, and this is mostly independent from the contribution of the actual attribute values in the choice options. That is, eye movements tell us not just about the processing of attribute values but also are independently associated with choice. The pattern is simple—people choose the gamble they look at more often, independently of the actual numbers they see—and this pattern is simpler than predicted by decision field theory, decision by sampling, and the parallel constraint satisfaction model. © 2015 The Authors. Journal of Behavioral Decision Making published by John Wiley & Sons Ltd. PMID:27522985

Determinants of Awareness, Consideration, and Choice Set Size in University Choice.

ERIC Educational Resources Information Center

Dawes, Philip L.; Brown, Jennifer

2002-01-01

Developed and tested a model of students' university "brand" choice using five individual-level variables (ethnic group, age, gender, number of parents going to university, and academic ability) and one situational variable (duration of search) to explain variation in the sizes of awareness, consideration, and choice decision sets. (EV)

Choice as a Global Language in Local Practice: A Mixed Model of School Choice in Taiwan

ERIC Educational Resources Information Center

Mao, Chin-Ju

2015-01-01

This paper uses school choice policy as an example to demonstrate how local actors adopt, mediate, translate, and reformulate "choice" as neo-liberal rhetoric informing education reform. Complex processes exist between global policy about school choice and the local practice of school choice. Based on the theoretical sensibility of…

Agency and Choice in Education: Does School Choice Enhance the Work Effort of Teachers?

ERIC Educational Resources Information Center

Rapp, Geoffrey C.

2000-01-01

Investigates effects of school-choice laws on U.S. teachers' work incentives, using 1993-94 Schools and Staffing Survey data. Examines whether school system competitiveness works to solve the principal-agent problem in education. Results are mixed, but suggest that one type of choice policy--intradistrict choice--enhances teacher motivation.…

Hobson's Choice: Illusory Intervention Choice for Culturally and Linguistically Diverse Learners with Problem Behaviors

ERIC Educational Resources Information Center

Obiakor, Festus E.

2012-01-01

Hobson's choice is a "no-choice" choice that gives general and special educators the traditional impetus to do what they want in classrooms. While there is some "goodness" in having this power and audacity to control whatever happens in classrooms, it does not allow for creativity, flexibility, adaptability, modification, especially in behavior…

Commuter choice primer : an employer's guide to implementing effective commuter choice programs

DOT National Transportation Integrated Search

2003-01-01

The Commuter Choice Primer is intended to be a concise, user-friendly reference guide for employers and transportation professionals to developing and implementing worksite commuter choice programs. It is available on-line in both HTML and PDF format...

On the problem of modeling for parameter identification in distributed structures

NASA Technical Reports Server (NTRS)

Norris, Mark A.; Meirovitch, Leonard

1988-01-01

Structures are often characterized by parameters, such as mass and stiffness, that are spatially distributed. Parameter identification of distributed structures is subject to many of the difficulties involved in the modeling problem, and the choice of the model can greatly affect the results of the parameter identification process. Analogously to control spillover in the control of distributed-parameter systems, identification spillover is shown to exist as well and its effect is to degrade the parameter estimates. Moreover, as in modeling by the Rayleigh-Ritz method, it is shown that, for a Rayleigh-Ritz type identification algorithm, an inclusion principle exists in the identification of distributed-parameter systems as well, so that the identified natural frequencies approach the actual natural frequencies monotonically from above.

Existence and instability of steady states for a triangular cross-diffusion system: A computer-assisted proof

NASA Astrophysics Data System (ADS)

Breden, Maxime; Castelli, Roberto

2018-05-01

In this paper, we present and apply a computer-assisted method to study steady states of a triangular cross-diffusion system. Our approach consist in an a posteriori validation procedure, that is based on using a fixed point argument around a numerically computed solution, in the spirit of the Newton-Kantorovich theorem. It allows to prove the existence of various non homogeneous steady states for different parameter values. In some situations, we obtain as many as 13 coexisting steady states. We also apply the a posteriori validation procedure to study the linear stability of the obtained steady states, proving that many of them are in fact unstable.

EDF's studies and first choices regarding the design of electrical equipment

NASA Technical Reports Server (NTRS)

Paris, Michel; Metzger, Gisele; Pays, Michel; Pasdeloup, Maurice

1988-01-01

In the performance of its studies and in its first choices, Electricite de France has taken into account the three parameters that have been judged essential for its electrical installations: flammability and flame propagation; smoke opacity; and corrosiveness and toxicity of emitted gases. In this research, materials tests have been widely developed in order to insure simple manufacturing controls, and to decrease the costly testing of near to full size models.

Parent Choice versus Attendance Area Assignment to Schools: Does Magnet-Based School Choice Affect NAEP Scores?

ERIC Educational Resources Information Center

Archbald, Douglas A.; Kaplan, David

2004-01-01

Inter- and intra-district public school choice, vouchers, tuition tax credits and other forms of school choice have been advocated for decades, in large part on grounds that the market forces engendered will improve public education. There are many studies of school choice policies and programs and a large theoretical literature on school choice,…

Temporal dynamics of choice behavior in rats and humans: an examination of pre- and post-choice latencies

PubMed Central

Fam, Justine; Westbrook, Fred; Arabzadeh, Ehsan

2016-01-01

Identifying similarities and differences in choice behavior across species is informative about how basic mechanisms give rise to more complex processes. In the present study, we compared pre- and post-choice latencies between rats and humans under two paradigms. In Experiment 1, we used a cued choice paradigm where subjects were presented with a cue that directed them as to which of two options to respond for rewards. In Experiment 2, subjects were free to choose between two options in order to procure rewards. In both Experiments rewards were delivered with distinct probabilities. The trial structure used in these experiments allowed the choice process to be decomposed into pre- and post-choice processes. Overall, post-choice latencies reflected the difference in reward probability between the two options, where latencies for the option with higher probability of reward were longer than those for the option with lower probability of reward. An interesting difference between rats and humans was observed: the choice behavior for humans, but not rats, was sensitive to the free-choice aspect of the tasks, such that in free-choice trials post-choice latencies no longer reflected the difference in reward probabilities between the two options. PMID:26862000

Efficient Bayesian parameter estimation with implicit sampling and surrogate modeling for a vadose zone hydrological problem

NASA Astrophysics Data System (ADS)

Liu, Y.; Pau, G. S. H.; Finsterle, S.

2015-12-01

Parameter inversion involves inferring the model parameter values based on sparse observations of some observables. To infer the posterior probability distributions of the parameters, Markov chain Monte Carlo (MCMC) methods are typically used. However, the large number of forward simulations needed and limited computational resources limit the complexity of the hydrological model we can use in these methods. In view of this, we studied the implicit sampling (IS) method, an efficient importance sampling technique that generates samples in the high-probability region of the posterior distribution and thus reduces the number of forward simulations that we need to run. For a pilot-point inversion of a heterogeneous permeability field based on a synthetic ponded infiltration experiment simu­lated with TOUGH2 (a subsurface modeling code), we showed that IS with linear map provides an accurate Bayesian description of the parameterized permeability field at the pilot points with just approximately 500 forward simulations. We further studied the use of surrogate models to improve the computational efficiency of parameter inversion. We implemented two reduced-order models (ROMs) for the TOUGH2 forward model. One is based on polynomial chaos expansion (PCE), of which the coefficients are obtained using the sparse Bayesian learning technique to mitigate the "curse of dimensionality" of the PCE terms. The other model is Gaussian process regression (GPR) for which different covariance, likelihood and inference models are considered. Preliminary results indicate that ROMs constructed based on the prior parameter space perform poorly. It is thus impractical to replace this hydrological model by a ROM directly in a MCMC method. However, the IS method can work with a ROM constructed for parameters in the close vicinity of the maximum a posteriori probability (MAP) estimate. We will discuss the accuracy and computational efficiency of using ROMs in the implicit sampling procedure

Eye Movements in Strategic Choice

PubMed Central

Gächter, Simon; Noguchi, Takao; Mullett, Timothy L.

2015-01-01

Abstract In risky and other multiattribute choices, the process of choosing is well described by random walk or drift diffusion models in which evidence is accumulated over time to threshold. In strategic choices, level‐k and cognitive hierarchy models have been offered as accounts of the choice process, in which people simulate the choice processes of their opponents or partners. We recorded the eye movements in 2 × 2 symmetric games including dominance‐solvable games like prisoner's dilemma and asymmetric coordination games like stag hunt and hawk–dove. The evidence was most consistent with the accumulation of payoff differences over time: we found longer duration choices with more fixations when payoffs differences were more finely balanced, an emerging bias to gaze more at the payoffs for the action ultimately chosen, and that a simple count of transitions between payoffs—whether or not the comparison is strategically informative—was strongly associated with the final choice. The accumulator models do account for these strategic choice process measures, but the level‐k and cognitive hierarchy models do not. © 2015 The Authors. Journal of Behavioral Decision Making published by John Wiley & Sons Ltd. PMID:27513881

Intertemporal choice in lemurs.

PubMed

Stevens, Jeffrey R; Mühlhoff, Nelly

2012-02-01

Different species vary in their ability to wait for delayed rewards in intertemporal choice tasks. Models of rate maximization account for part of this variation, but other factors such as social structure and feeding ecology seem to underly some species differences. Though studies have evaluated intertemporal choice in several primate species, including Old World monkeys, New World monkeys, and apes, prosimians have not been tested. This study investigated intertemporal choices in three species of lemur (black-and-white ruffed lemurs, Varecia variegata, red ruffed lemurs, Varecia rubra, and black lemurs, Eulemur macaco) to assess how they compare to other primate species and whether their choices are consistent with rate maximization. We offered lemurs a choice between two food items available immediately and six food items available after a delay. We found that by adjusting the delay to the larger reward, the lemurs were indifferent between the two options at a mean delay of 17 s, ranging from 9 to 25 s. These data are comparable to data collected from common marmosets (Callithrix jacchus). The lemur data were not consistent with models of rate maximization. The addition of lemurs to the list of species tested in these tasks will help uncover the role of life history and socio-ecological factors influencing intertemporal choices. Copyright © 2011 Elsevier B.V. All rights reserved.

Factoring out nondecision time in choice reaction time data: Theory and implications.

PubMed

Verdonck, Stijn; Tuerlinckx, Francis

2016-03-01

Choice reaction time (RT) experiments are an invaluable tool in psychology and neuroscience. A common assumption is that the total choice response time is the sum of a decision and a nondecision part (time spent on perceptual and motor processes). While the decision part is typically modeled very carefully (commonly with diffusion models), a simple and ad hoc distribution (mostly uniform) is assumed for the nondecision component. Nevertheless, it has been shown that the misspecification of the nondecision time can severely distort the decision model parameter estimates. In this article, we propose an alternative approach to the estimation of choice RT models that elegantly bypasses the specification of the nondecision time distribution by means of an unconventional convolution of data and decision model distributions (hence called the D*M approach). Once the decision model parameters have been estimated, it is possible to compute a nonparametric estimate of the nondecision time distribution. The technique is tested on simulated data, and is shown to systematically remove traditional estimation bias related to misspecified nondecision time, even for a relatively small number of observations. The shape of the actual underlying nondecision time distribution can also be recovered. Next, the D*M approach is applied to a selection of existing diffusion model application articles. For all of these studies, substantial quantitative differences with the original analyses are found. For one study, these differences radically alter its final conclusions, underlining the importance of our approach. Additionally, we find that strongly right skewed nondecision time distributions are not at all uncommon. (c) 2016 APA, all rights reserved).

Isolating behavioral mechanisms of intertemporal choice: nicotine effects on delay discounting and amount sensitivity.

PubMed

Locey, Matthew L; Dallery, Jesse

2009-03-01

Many drugs of abuse produce changes in impulsive choice, that is, choice for a smaller-sooner reinforcer over a larger-later reinforcer. Because the alternatives differ in both delay and amount, it is not clear whether these drug effects are due to the differences in reinforcer delay or amount. To isolate the effects of delay, we used a titrating delay procedure. In phase 1, 9 rats made discrete choices between variable delays (1 or 19 s, equal probability of each) and a delay to a single food pellet. The computer titrated the delay to a single food pellet until the rats were indifferent between the two options. This indifference delay was used as the starting value for the titrating delay for all future sessions. We next evaluated the acute effects of nicotine (subcutaneous 1.0, 0.3, 0.1, and 0.03 mg/kg) on choice. If nicotine increases delay discounting, it should have increased preference for the variable delay. Instead, nicotine had very little effect on choice. In a second phase, the titrated delay alternative produced three food pellets instead of one, which was again produced by the variable delay (1 s or 19 s) alternative. Under this procedure, nicotine increased preference for the one pellet alternative. Nicotine-induced changes in impulsive choice are therefore likely due to differences in reinforcer amount rather than differences in reinforcer delay. In addition, it may be necessary to include an amount sensitivity parameter in any mathematical model of choice when the alternatives differ in reinforcer amount.

Connectivity between mPFC and PCC predicts post-choice attitude change: The self-referential processing hypothesis of choice justification.

PubMed

Tompson, Steven; Chua, Hannah Faye; Kitayama, Shinobu

2016-11-01

Prior research shows that after making a choice, decision makers shift their attitudes in a choice-congruous direction. Although this post-choice attitude change effect is robust, the neural mechanisms underlying it are poorly understood. Here, we tested the hypothesis that decision makers elaborate on their choice in reference to self-knowledge to justify the choice they have made. This self-referential processing of the choice is thought to play a pivotal role in the post-choice attitude change. Twenty-four young American adults made a series of choices. They also rated their attitudes toward the choice options before and after the choices. In support of the current hypothesis, we found that changes in functional connectivity between two putative self-regions (medial prefrontal cortex and posterior cingulate cortex/precuneus]) during the post-choice (vs. pre-choice) rating of the chosen options predicted the post-choice shift of the attitudes toward the chosen options. This finding is the first to suggest that cognitive integration of various self-relevant cognitions is instrumental in fostering post-choice attitude change. Hum Brain Mapp 37:3810-3820, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Evaluating choices by single neurons in the frontal lobe: outcome value encoded across multiple decision variables

PubMed Central

Kennerley, Steven W.; Wallis, Jonathan D.

2009-01-01

Damage to the frontal lobe can cause severe decision-making impairments. A mechanism that may underlie this is that neurons in the frontal cortex encode many variables that contribute to the valuation of a choice, such as its costs, benefits and probability of success. However, optimal decision-making requires that one considers these variables, not only when faced with the choice, but also when evaluating the outcome of the choice, in order to adapt future behaviour appropriately. To examine the role of the frontal cortex in encoding the value of different choice outcomes, we simultaneously recorded the activity of multiple single neurons in the anterior cingulate cortex (ACC), orbitofrontal cortex (OFC) and lateral prefrontal cortex (LPFC) while subjects evaluated the outcome of choices involving manipulations of probability, payoff and cost. Frontal neurons encoded many of the parameters that enabled the calculation of the value of these variables, including the onset and offset of reward and the amount of work performed, and often encoded the value of outcomes across multiple decision variables. In addition, many neurons encoded both the predicted outcome during the choice phase of the task as well as the experienced outcome in the outcome phase of the task. These patterns of selectivity were more prevalent in ACC relative to OFC and LPFC. These results support a role for the frontal cortex, principally ACC, in selecting between choice alternatives and evaluating the outcome of that selection thereby ensuring that choices are optimal and adaptive. PMID:19453638

Ventromedial prefrontal and anterior cingulate cortex adopt choice and default reference frames during sequential multialternative choice

PubMed Central

Boorman, Erie D; Rushworth, Matthew F; Behrens, Tim E

2013-01-01

Although damage to medial frontal cortex causes profound decision-making impairments, it has been difficult to pinpoint the relative contributions of key anatomical subdivisions. Here we use fMRI to examine the contributions of human ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortex (dACC) during sequential choices between multiple alternatives – two key features of choices made in ecological settings. By carefully constructing options whose current value at any given decision was dissociable from their longer-term value, we were able to examine choices in current and long-term frames of reference. We present evidence showing that activity at choice and feedback in vmPFC and dACC was tied to the current choice and the best long-term option, respectively. vmPFC, mid-cingulate, and PCC encoded the relative value between the chosen and next-best option at each sequential decision, whereas dACC encoded the relative value of adapting choices from the option with the highest value in the longer-term. Furthermore, at feedback we identify temporally dissociable effects that predict repetition of the current choice and adaptation away from the long-term best option in vmPFC and dACC, respectively. These functional dissociations at choice and feedback suggest that sequential choices are subject to competing cortical mechanisms. PMID:23392656

Choice of Variables and Preconditioning for Time Dependent Problems

NASA Technical Reports Server (NTRS)

Turkel, Eli; Vatsa, Verr N.

2003-01-01

We consider the use of low speed preconditioning for time dependent problems. These are solved using a dual time step approach. We consider the effect of this dual time step on the parameter of the low speed preconditioning. In addition, we compare the use of two sets of variables, conservation and primitive variables, to solve the system. We show the effect of these choices on both the convergence to a steady state and the accuracy of the numerical solutions for low Mach number steady state and time dependent flows.

Measures of GCM Performance as Functions of Model Parameters Affecting Clouds and Radiation

NASA Astrophysics Data System (ADS)

Jackson, C.; Mu, Q.; Sen, M.; Stoffa, P.

2002-05-01

This abstract is one of three related presentations at this meeting dealing with several issues surrounding optimal parameter and uncertainty estimation of model predictions of climate. Uncertainty in model predictions of climate depends in part on the uncertainty produced by model approximations or parameterizations of unresolved physics. Evaluating these uncertainties is computationally expensive because one needs to evaluate how arbitrary choices for any given combination of model parameters affects model performance. Because the computational effort grows exponentially with the number of parameters being investigated, it is important to choose parameters carefully. Evaluating whether a parameter is worth investigating depends on two considerations: 1) does reasonable choices of parameter values produce a large range in model response relative to observational uncertainty? and 2) does the model response depend non-linearly on various combinations of model parameters? We have decided to narrow our attention to selecting parameters that affect clouds and radiation, as it is likely that these parameters will dominate uncertainties in model predictions of future climate. We present preliminary results of ~20 to 30 AMIPII style climate model integrations using NCAR's CCM3.10 that show model performance as functions of individual parameters controlling 1) critical relative humidity for cloud formation (RHMIN), and 2) boundary layer critical Richardson number (RICR). We also explore various definitions of model performance that include some or all observational data sources (surface air temperature and pressure, meridional and zonal winds, clouds, long and short-wave cloud forcings, etc...) and evaluate in a few select cases whether the model's response depends non-linearly on the parameter values we have selected.

Making Smart Food Choices

MedlinePlus

... turn JavaScript on. Feature: Healthy Aging Making Smart Food Choices Past Issues / Winter 2015 Table of Contents ... NIH www.nia.nih.gov/Go4Life Making Smart Food Choices To maintain a healthy weight, balance the ...

Dynamics of Choice: A Tutorial

ERIC Educational Resources Information Center

Baum, William M.

2010-01-01

Choice may be defined as the allocation of behavior among activities. Since all activities take up time, choice is conveniently thought of as the allocation of time among activities, even if activities like pecking are most easily measured by counting. Since dynamics refers to change through time, the dynamics of choice refers to change of…

What counts as a choice? U.S. Americans are more likely than Indians to construe actions as choices.

PubMed

Savani, Krishna; Markus, Hazel Rose; Naidu, N V R; Kumar, Satishchandra; Berlia, Neha

2010-03-01

People everywhere select among multiple alternatives, but are they always making choices? In five studies, we found that people in U.S. American contexts, where the disjoint model of agency is prevalent, are more likely than those in Indian contexts to construe their own and other individuals' behaviors as choices, to construe ongoing behaviors and behaviors recalled from memory as choices, to construe naturally occurring and experimentally controlled behaviors as choices, to construe mundane and important actions as choices, and to construe personal and interpersonal actions as choices. Indians showed a greater tendency to construe actions as choices when these actions involved responding to other people than when they did not. These findings show that whether people construe actions as choices is significantly shaped by sociocultural systems of meanings and practices. Together, they suggest that the positive consequences associated with maximizing the availability of personal choice may not be universal and instead may be limited to North American contexts.

More Choice Isn't Always Better

ERIC Educational Resources Information Center

Schuller, Tom

2012-01-01

Choice is important to everyone, for one's identity as well as one's material satisfaction. Everyone has choices, but even the head of state's choices are constrained. In recent years choice has risen up the political agenda in the UK. It has become a key component of the drive to reform public services such as health and education. The…

Extension of the Optimized Virtual Fields Method to estimate viscoelastic material parameters from 3D dynamic displacement fields

PubMed Central

Connesson, N.; Clayton, E.H.; Bayly, P.V.; Pierron, F.

2015-01-01

In-vivo measurement of the mechanical properties of soft tissues is essential to provide necessary data in biomechanics and medicine (early cancer diagnosis, study of traumatic brain injuries, etc.). Imaging techniques such as Magnetic Resonance Elastography (MRE) can provide 3D displacement maps in the bulk and in vivo, from which, using inverse methods, it is then possible to identify some mechanical parameters of the tissues (stiffness, damping etc.). The main difficulties in these inverse identification procedures consist in dealing with the pressure waves contained in the data and with the experimental noise perturbing the spatial derivatives required during the processing. The Optimized Virtual Fields Method (OVFM) [1], designed to be robust to noise, present natural and rigorous solution to deal with these problems. The OVFM has been adapted to identify material parameter maps from Magnetic Resonance Elastography (MRE) data consisting of 3-dimensional displacement fields in harmonically loaded soft materials. In this work, the method has been developed to identify elastic and viscoelastic models. The OVFM sensitivity to spatial resolution and to noise has been studied by analyzing 3D analytically simulated displacement data. This study evaluates and describes the OVFM identification performances: different biases on the identified parameters are induced by the spatial resolution and experimental noise. The well-known identification problems in the case of quasi-incompressible materials also find a natural solution in the OVFM. Moreover, an a posteriori criterion to estimate the local identification quality is proposed. The identification results obtained on actual experiments are briefly presented. PMID:26146416

Traffic-Light Labels and Choice Architecture Promoting Healthy Food Choices

PubMed Central

Thorndike, Anne N.; Riis, Jason; Sonnenberg, Lillian M.; Levy, Douglas E.

2014-01-01

Background Preventing obesity requires maintenance of healthy eating behaviors over time. Food labels and strategies that increase visibility and convenience of healthy foods (choice architecture) promote healthier choices, but long-term effectiveness is unknown. Purpose Assess effectiveness of traffic-light labeling and choice architecture cafeteria intervention over 24 months. Design Longitudinal pre–post cohort follow-up study between December 2009 and February 2012. Data were analyzed in 2012. Setting/participants Large hospital cafeteria with mean of 6511 transactions daily. Cafeteria sales were analyzed for: (1) all cafeteria customers and (2) longitudinal cohort of 2285 hospital employees who used the cafeteria regularly. Intervention After 3-month baseline period, cafeteria items were labeled green (healthy), yellow (less healthy) or red (unhealthy) and rearranged to make healthy items more accessible. Main outcome measures Proportion of cafeteria sales that were green or red during each 3-month period from baseline to 24 months. Changes in 12- and 24-month sales were compared to baseline for all transactions and transactions by the employee cohort. Results The proportion of sales of red items decreased from 24% at baseline to 20% at 24 months (p<0.001), and green sales increased from 41% to 46% (p<0.001). Red beverages decreased from 26% of beverage sales at baseline to 17% at 24 months (p<0.001); green beverages increased from 52% to 60% (p<0.001). Similar patterns were observed for the cohort of employees, with largest change for red beverages (23% to 14%, p<0.001). Conclusions A traffic-light and choice architecture cafeteria intervention resulted in sustained healthier choices over 2 years, suggesting food environment interventions can promote long-term changes in population eating behaviors. PMID:24439347

Traffic-light labels and choice architecture: promoting healthy food choices.

PubMed

Thorndike, Anne N; Riis, Jason; Sonnenberg, Lillian M; Levy, Douglas E

2014-02-01

Preventing obesity requires maintenance of healthy eating behaviors over time. Food labels and strategies that increase visibility and convenience of healthy foods (choice architecture) promote healthier choices, but long-term effectiveness is unknown. Assess effectiveness of traffic-light labeling and choice architecture cafeteria intervention over 24 months. Longitudinal pre-post cohort follow-up study between December 2009 and February 2012. Data were analyzed in 2012. Large hospital cafeteria with a mean of 6511 transactions daily. Cafeteria sales were analyzed for (1) all cafeteria customers and (2) a longitudinal cohort of 2285 hospital employees who used the cafeteria regularly. After a 3-month baseline period, cafeteria items were labeled green (healthy); yellow (less healthy); or red (unhealthy) and rearranged to make healthy items more accessible. Proportion of cafeteria sales that were green or red during each 3-month period from baseline to 24 months. Changes in 12- and 24-month sales were compared to baseline for all transactions and transactions by the employee cohort. The proportion of sales of red items decreased from 24% at baseline to 20% at 24 months (p<0.001), and green sales increased from 41% to 46% (p<0.001). Red beverages decreased from 26% of beverage sales at baseline to 17% at 24 months (p<0.001); green beverages increased from 52% to 60% (p<0.001). Similar patterns were observed for the cohort of employees, with the largest change for red beverages (23%-14%, p<0.001). A traffic-light and choice architecture cafeteria intervention resulted in sustained healthier choices over 2 years, suggesting that food environment interventions can promote long-term changes in population eating behaviors. © 2013 American Journal of Preventive Medicine Published by American Journal of Preventive Medicine All rights reserved.

Orbitofrontal cortical activity during repeated free choice.

PubMed

Campos, Michael; Koppitch, Kari; Andersen, Richard A; Shimojo, Shinsuke

2012-06-01

Neurons in the orbitofrontal cortex (OFC) have been shown to encode subjective values, suggesting a role in preference-based decision-making, although the precise relation to choice behavior is unclear. In a repeated two-choice task, subjective values of each choice can account for aggregate choice behavior, which is the overall likelihood of choosing one option over the other. Individual choices, however, are impossible to predict with knowledge of relative subjective values alone. In this study we investigated the role of internal factors in choice behavior with a simple but novel free-choice task and simultaneous recording from individual neurons in nonhuman primate OFC. We found that, first, the observed sequences of choice behavior included periods of exceptionally long runs of each of two available options and periods of frequent switching. Neither a satiety-based mechanism nor a random selection process could explain the observed choice behavior. Second, OFC neurons encode important features of the choice behavior. These features include activity selective for exceptionally long runs of a given choice (stay selectivity) as well as activity selective for switches between choices (switch selectivity). These results suggest that OFC neural activity, in addition to encoding subjective values on a long timescale that is sensitive to satiety, also encodes a signal that fluctuates on a shorter timescale and thereby reflects some of the statistically improbable aspects of free-choice behavior.

Orbitofrontal cortical activity during repeated free choice

PubMed Central

Koppitch, Kari; Andersen, Richard A.; Shimojo, Shinsuke

2012-01-01

Neurons in the orbitofrontal cortex (OFC) have been shown to encode subjective values, suggesting a role in preference-based decision-making, although the precise relation to choice behavior is unclear. In a repeated two-choice task, subjective values of each choice can account for aggregate choice behavior, which is the overall likelihood of choosing one option over the other. Individual choices, however, are impossible to predict with knowledge of relative subjective values alone. In this study we investigated the role of internal factors in choice behavior with a simple but novel free-choice task and simultaneous recording from individual neurons in nonhuman primate OFC. We found that, first, the observed sequences of choice behavior included periods of exceptionally long runs of each of two available options and periods of frequent switching. Neither a satiety-based mechanism nor a random selection process could explain the observed choice behavior. Second, OFC neurons encode important features of the choice behavior. These features include activity selective for exceptionally long runs of a given choice (stay selectivity) as well as activity selective for switches between choices (switch selectivity). These results suggest that OFC neural activity, in addition to encoding subjective values on a long timescale that is sensitive to satiety, also encodes a signal that fluctuates on a shorter timescale and thereby reflects some of the statistically improbable aspects of free-choice behavior. PMID:22423007

Estimating system parameters for solvent-water and plant cuticle-water using quantum chemically estimated Abraham solute parameters.

PubMed

Liang, Yuzhen; Torralba-Sanchez, Tifany L; Di Toro, Dominic M

2018-04-18

Polyparameter Linear Free Energy Relationships (pp-LFERs) using Abraham system parameters have many useful applications. However, developing the Abraham system parameters depends on the availability and quality of the Abraham solute parameters. Using Quantum Chemically estimated Abraham solute Parameters (QCAP) is shown to produce pp-LFERs that have lower root mean square errors (RMSEs) of predictions for solvent-water partition coefficients than parameters that are estimated using other presently available methods. pp-LFERs system parameters are estimated for solvent-water, plant cuticle-water systems, and for novel compounds using QCAP solute parameters and experimental partition coefficients. Refitting the system parameter improves the calculation accuracy and eliminates the bias. Refitted models for solvent-water partition coefficients using QCAP solute parameters give better results (RMSE = 0.278 to 0.506 log units for 24 systems) than those based on ABSOLV (0.326 to 0.618) and QSPR (0.294 to 0.700) solute parameters. For munition constituents and munition-like compounds not included in the calibration of the refitted model, QCAP solute parameters produce pp-LFER models with much lower RMSEs for solvent-water partition coefficients (RMSE = 0.734 and 0.664 for original and refitted model, respectively) than ABSOLV (4.46 and 5.98) and QSPR (2.838 and 2.723). Refitting plant cuticle-water pp-LFER including munition constituents using QCAP solute parameters also results in lower RMSE (RMSE = 0.386) than that using ABSOLV (0.778) and QSPR (0.512) solute parameters. Therefore, for fitting a model in situations for which experimental data exist and system parameters can be re-estimated, or for which system parameters do not exist and need to be developed, QCAP is the quantum chemical method of choice.

School Choice: The Personal and the Political

ERIC Educational Resources Information Center

Shuls, James V.

2018-01-01

Enrollment in school choice programs is growing, so is overall support for school choice. Many have analyzed what demographic characteristics impact attitudes towards school choice. This article adds to the literature by exploring the interaction between personal decisions regarding school choice and broader support for school choice programs.…

Refocusing College Choice: Women's Reflections on Their Postsecondary Education Choices

ERIC Educational Resources Information Center

Bergerson, Amy A.; Heiselt, April K.; Aiken-Wisniewski, Sharon

2013-01-01

College choice is often tied to persistence and it emphasizes how family background affects both enrollment in higher education and persistence to degree. Despite extensive research related to both access to higher education and choice processes, there is still much to be learned about students' postsecondary decisions. This qualitative study…

The use of predictive models to optimize risk of decisions.

PubMed

Baranyi, József; Buss da Silva, Nathália

2017-01-02

The purpose of this paper is to set up a mathematical framework that risk assessors and regulators could use to quantify the "riskiness" of a particular recommendation (choice/decision). The mathematical theory introduced here can be used for decision support systems. We point out that efficient use of predictive models in decision making for food microbiology needs to consider three major points: (1) the uncertainty and variability of the used information based on which the decision is to be made; (2) the validity of the predictive models aiding the assessor; and (3) the cost generated by the difference between the a-priory choice and the a-posteriori outcome. Copyright © 2016 Elsevier B.V. All rights reserved.

Risk preferences impose a hidden distortion on measures of choice impulsivity

PubMed Central

Konova, Anna B.; Louie, Kenway; Glimcher, Paul W.

2018-01-01

Measuring temporal discounting through the use of intertemporal choice tasks is now the gold standard method for quantifying human choice impulsivity (impatience) in neuroscience, psychology, behavioral economics, public health and computational psychiatry. A recent area of growing interest is individual differences in discounting levels, as these may predispose to (or protect from) mental health disorders, addictive behaviors, and other diseases. At the same time, more and more studies have been dedicated to the quantification of individual attitudes towards risk, which have been measured in many clinical and non-clinical populations using closely related techniques. Economists have pointed to interactions between measurements of time preferences and risk preferences that may distort estimations of the discount rate. However, although becoming standard practice in economics, discount rates and risk preferences are rarely measured simultaneously in the same subjects in other fields, and the magnitude of the imposed distortion is unknown in the assessment of individual differences. Here, we show that standard models of temporal discounting —such as a hyperbolic discounting model widely present in the literature which fails to account for risk attitudes in the estimation of discount rates— result in a large and systematic pattern of bias in estimated discounting parameters. This can lead to the spurious attribution of differences in impulsivity between individuals when in fact differences in risk attitudes account for observed behavioral differences. We advance a model which, when applied to standard choice tasks typically used in psychology and neuroscience, provides both a better fit to the data and successfully de-correlates risk and impulsivity parameters. This results in measures that are more accurate and thus of greater utility to the many fields interested in individual differences in impulsivity. PMID:29373590

Risk preferences impose a hidden distortion on measures of choice impulsivity.

PubMed

Lopez-Guzman, Silvia; Konova, Anna B; Louie, Kenway; Glimcher, Paul W

2018-01-01

Measuring temporal discounting through the use of intertemporal choice tasks is now the gold standard method for quantifying human choice impulsivity (impatience) in neuroscience, psychology, behavioral economics, public health and computational psychiatry. A recent area of growing interest is individual differences in discounting levels, as these may predispose to (or protect from) mental health disorders, addictive behaviors, and other diseases. At the same time, more and more studies have been dedicated to the quantification of individual attitudes towards risk, which have been measured in many clinical and non-clinical populations using closely related techniques. Economists have pointed to interactions between measurements of time preferences and risk preferences that may distort estimations of the discount rate. However, although becoming standard practice in economics, discount rates and risk preferences are rarely measured simultaneously in the same subjects in other fields, and the magnitude of the imposed distortion is unknown in the assessment of individual differences. Here, we show that standard models of temporal discounting -such as a hyperbolic discounting model widely present in the literature which fails to account for risk attitudes in the estimation of discount rates- result in a large and systematic pattern of bias in estimated discounting parameters. This can lead to the spurious attribution of differences in impulsivity between individuals when in fact differences in risk attitudes account for observed behavioral differences. We advance a model which, when applied to standard choice tasks typically used in psychology and neuroscience, provides both a better fit to the data and successfully de-correlates risk and impulsivity parameters. This results in measures that are more accurate and thus of greater utility to the many fields interested in individual differences in impulsivity.

A likelihood-based biostatistical model for analyzing consumer movement in simultaneous choice experiments.

PubMed

Zeilinger, Adam R; Olson, Dawn M; Andow, David A

2014-08-01

Consumer feeding preference among resource choices has critical implications for basic ecological and evolutionary processes, and can be highly relevant to applied problems such as ecological risk assessment and invasion biology. Within consumer choice experiments, also known as feeding preference or cafeteria experiments, measures of relative consumption and measures of consumer movement can provide distinct and complementary insights into the strength, causes, and consequences of preference. Despite the distinct value of inferring preference from measures of consumer movement, rigorous and biologically relevant analytical methods are lacking. We describe a simple, likelihood-based, biostatistical model for analyzing the transient dynamics of consumer movement in a paired-choice experiment. With experimental data consisting of repeated discrete measures of consumer location, the model can be used to estimate constant consumer attraction and leaving rates for two food choices, and differences in choice-specific attraction and leaving rates can be tested using model selection. The model enables calculation of transient and equilibrial probabilities of consumer-resource association, which could be incorporated into larger scale movement models. We explore the effect of experimental design on parameter estimation through stochastic simulation and describe methods to check that data meet model assumptions. Using a dataset of modest sample size, we illustrate the use of the model to draw inferences on consumer preference as well as underlying behavioral mechanisms. Finally, we include a user's guide and computer code scripts in R to facilitate use of the model by other researchers.

A multiple indicator solution approach to endogeneity in discrete-choice models for environmental valuation.

PubMed

Mariel, Petr; Hoyos, David; Artabe, Alaitz; Guevara, C Angelo

2018-08-15

Endogeneity is an often neglected issue in empirical applications of discrete choice modelling despite its severe consequences in terms of inconsistent parameter estimation and biased welfare measures. This article analyses the performance of the multiple indicator solution method to deal with endogeneity arising from omitted explanatory variables in discrete choice models for environmental valuation. We also propose and illustrate a factor analysis procedure for the selection of the indicators in practice. Additionally, the performance of this method is compared with the recently proposed hybrid choice modelling framework. In an empirical application we find that the multiple indicator solution method and the hybrid model approach provide similar results in terms of welfare estimates, although the multiple indicator solution method is more parsimonious and notably easier to implement. The empirical results open a path to explore the performance of this method when endogeneity is thought to have a different cause or under a different set of indicators. Copyright © 2018 Elsevier B.V. All rights reserved.

Performing a Choice-Narrative: A qualitative study of the patterns in STEM students' higher education choices

NASA Astrophysics Data System (ADS)

Tolstrup Holmegaard, Henriette

2015-06-01

Students' science choices have long attracted attention in both public and research. Recently there has been a call for qualitative studies to explore how choices create a sense of fit for individual students. Therefore, this paper aims to study how science students' choices of higher education are performed and to uncover the patterns of students' construction of their choice-narratives. The paper is based on a qualitative study among 38 Danish upper secondary school students. The theoretical framework is narrative psychology combined with post-structural thinking. The study shows that constructing a choice-narrative is complicated identity-work. First, the students felt encouraged to identify their interests, not only the ones related to the subject matter, but also various interests that were equally negotiated in relation to each other. Second, the choice-narratives were personalised; on the one side articulated as not too predictable, and on the other side appearing realistic and adjusted to the students' sense of self. Third, the choice-narratives were informed, validated and adjusted in the students' social network providing the students with a repertoire of viable pathways. The study demonstrates how cultural discourses about how a proper choice is made set the scene for the students' choices. The study raises some concerns for science education. Improving students' interests in science alone might not lead to increased admission as several interests equally intervene. To attract more students to science, we must consider how to actively engage them in crafting their own education, as a way to support them in making personal sense.

Will Choice Hurt? Compared to What? A School Choice Experiment in Estonia

ERIC Educational Resources Information Center

Põder, Kaire; Lauri, Triin

2014-01-01

This article presents the empirical analysis of the effects of a school choice policy in Estonia. The article shows that relying on markets and giving autonomy to the schools over student selection will produce admission tests, even at the elementary school level. This article's contribution is to show that a school choice policy experiment with…

A guide to multi-objective optimization for ecological problems with an application to cackling goose management

USGS Publications Warehouse

Williams, Perry J.; Kendall, William L.

2017-01-01

Choices in ecological research and management are the result of balancing multiple, often competing, objectives. Multi-objective optimization (MOO) is a formal decision-theoretic framework for solving multiple objective problems. MOO is used extensively in other fields including engineering, economics, and operations research. However, its application for solving ecological problems has been sparse, perhaps due to a lack of widespread understanding. Thus, our objective was to provide an accessible primer on MOO, including a review of methods common in other fields, a review of their application in ecology, and a demonstration to an applied resource management problem.A large class of methods for solving MOO problems can be separated into two strategies: modelling preferences pre-optimization (the a priori strategy), or modelling preferences post-optimization (the a posteriori strategy). The a priori strategy requires describing preferences among objectives without knowledge of how preferences affect the resulting decision. In the a posteriori strategy, the decision maker simultaneously considers a set of solutions (the Pareto optimal set) and makes a choice based on the trade-offs observed in the set. We describe several methods for modelling preferences pre-optimization, including: the bounded objective function method, the lexicographic method, and the weighted-sum method. We discuss modelling preferences post-optimization through examination of the Pareto optimal set. We applied each MOO strategy to the natural resource management problem of selecting a population target for cackling goose (Branta hutchinsii minima) abundance. Cackling geese provide food security to Native Alaskan subsistence hunters in the goose's nesting area, but depredate crops on private agricultural fields in wintering areas. We developed objective functions to represent the competing objectives related to the cackling goose population target and identified an optimal solution

The methodology of choice Cam-Clay model parameters for loess subsoil

NASA Astrophysics Data System (ADS)

Nepelski, Krzysztof; Błazik-Borowa, Ewa

2018-01-01

The paper deals with the calibration method of FEM subsoil model described by the constitutive Cam-Clay model. The four-storey residential building and solid substrate are modelled. Identification of the substrate is made using research drilling, CPT static tests, DMT Marchetti dilatometer, and laboratory tests. Latter are performed on the intact soil specimens which are taken from the wide planning trench at the depth of foundation. The real building settlements was measured as the vertical displacement of benchmarks. These measurements were carried out periodically during the erection of the building and its operation. Initially, the Cam Clay model parameters were determined on the basis of the laboratory tests, and later, they were corrected by taking into consideration numerical analyses results (whole building and its parts) and real building settlements.

TADtool: visual parameter identification for TAD-calling algorithms.

PubMed

Kruse, Kai; Hug, Clemens B; Hernández-Rodríguez, Benjamín; Vaquerizas, Juan M

2016-10-15

Eukaryotic genomes are hierarchically organized into topologically associating domains (TADs). The computational identification of these domains and their associated properties critically depends on the choice of suitable parameters of TAD-calling algorithms. To reduce the element of trial-and-error in parameter selection, we have developed TADtool: an interactive plot to find robust TAD-calling parameters with immediate visual feedback. TADtool allows the direct export of TADs called with a chosen set of parameters for two of the most common TAD calling algorithms: directionality and insulation index. It can be used as an intuitive, standalone application or as a Python package for maximum flexibility. TADtool is available as a Python package from GitHub (https://github.com/vaquerizaslab/tadtool) or can be installed directly via PyPI, the Python package index (tadtool). kai.kruse@mpi-muenster.mpg.de, jmv@mpi-muenster.mpg.deSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

Choice from non-choice: Predicting consumer preferences from BOLD signals obtained during passive viewing

PubMed Central

Levy, Ifat; Lazzaro, Stephanie C.; Rutledge, Robb B.; Glimcher, Paul W.

2011-01-01

Decision-making is often viewed as a two-stage process, where subjective values are first assigned to each option and then the option of the highest value is selected. Converging evidence suggests that these subjective values are represented in the striatum and medial prefrontal cortex (MPFC). A separate line of evidence suggests that activation in the same areas represents the values of rewards even when choice is not required, as in classical conditioning tasks. However, it is unclear whether the same neural mechanism is engaged in both cases. To address this question we measured brain activation with fMRI while human subjects passively viewed individual consumer goods. We then sampled activation from predefined regions of interest and used it to predict subsequent choices between the same items made outside of the scanner. Our results show that activation in the striatum and MPFC in the absence of choice predicts subsequent choices, suggesting that these brain areas represent value in a similar manner whether or not choice is required. PMID:21209196

The downside of choice: Having a choice benefits enjoyment, but at a cost to efficiency and time in visual search.

PubMed

Kunar, Melina A; Ariyabandu, Surani; Jami, Zaffran

2016-04-01

The efficiency of how people search for an item in visual search has, traditionally, been thought to depend on bottom-up or top-down guidance cues. However, recent research has shown that the rate at which people visually search through a display is also affected by cognitive strategies. In this study, we investigated the role of choice in visual search, by asking whether giving people a choice alters both preference for a cognitively neutral task and search behavior. Two visual search conditions were examined: one in which participants were given a choice of visual search task (the choice condition), and one in which participants did not have a choice (the no-choice condition). The results showed that the participants in the choice condition rated the task as both more enjoyable and likeable than did the participants in the no-choice condition. However, despite their preferences, actual search performance was slower and less efficient in the choice condition than in the no-choice condition (Exp. 1). Experiment 2 showed that the difference in search performance between the choice and no-choice conditions disappeared when central executive processes became occupied with a task-switching task. These data concur with a choice-impaired hypothesis of search, in which having a choice leads to more motivated, active search involving executive processes.

Neural Activity Reveals Preferences Without Choices

PubMed Central

Smith, Alec; Bernheim, B. Douglas; Camerer, Colin

2014-01-01

We investigate the feasibility of inferring the choices people would make (if given the opportunity) based on their neural responses to the pertinent prospects when they are not engaged in actual decision making. The ability to make such inferences is of potential value when choice data are unavailable, or limited in ways that render standard methods of estimating choice mappings problematic. We formulate prediction models relating choices to “non-choice” neural responses and use them to predict out-of-sample choices for new items and for new groups of individuals. The predictions are sufficiently accurate to establish the feasibility of our approach. PMID:25729468

Evoked Emotions Predict Food Choice

PubMed Central

Dalenberg, Jelle R.; Gutjar, Swetlana; ter Horst, Gert J.; de Graaf, Kees; Renken, Remco J.; Jager, Gerry

2014-01-01

In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments. Therefore, the focus within recent studies shifted towards using emotion-profiling methods that successfully can discriminate between products that are equally liked. However, it is unclear how well scores from emotion-profiling methods predict actual food choice and/or consumption. To test this, we proposed to decompose emotion scores into valence and arousal scores using Principal Component Analysis (PCA) and apply Multinomial Logit Models (MLM) to estimate food choice using liking, valence, and arousal as possible predictors. For this analysis, we used an existing data set comprised of liking and food-evoked emotions scores from 123 participants, who rated 7 unlabeled breakfast drinks. Liking scores were measured using a 100-mm visual analogue scale, while food-evoked emotions were measured using 2 existing emotion-profiling methods: a verbal and a non-verbal method (EsSense Profile and PrEmo, respectively). After 7 days, participants were asked to choose 1 breakfast drink from the experiment to consume during breakfast in a simulated restaurant environment. Cross validation showed that we were able to correctly predict individualized food choice (1 out of 7 products) for over 50% of the participants. This number increased to nearly 80% when looking at the top 2 candidates. Model comparisons showed that evoked emotions better predict food choice than perceived liking alone. However, the strongest predictive strength was achieved by the combination of evoked emotions and liking. Furthermore we showed that non-verbal food-evoked emotion scores more accurately predict food choice than verbal food-evoked emotions scores. PMID:25521352

Evoked emotions predict food choice.

PubMed

Dalenberg, Jelle R; Gutjar, Swetlana; Ter Horst, Gert J; de Graaf, Kees; Renken, Remco J; Jager, Gerry

2014-01-01

In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments. Therefore, the focus within recent studies shifted towards using emotion-profiling methods that successfully can discriminate between products that are equally liked. However, it is unclear how well scores from emotion-profiling methods predict actual food choice and/or consumption. To test this, we proposed to decompose emotion scores into valence and arousal scores using Principal Component Analysis (PCA) and apply Multinomial Logit Models (MLM) to estimate food choice using liking, valence, and arousal as possible predictors. For this analysis, we used an existing data set comprised of liking and food-evoked emotions scores from 123 participants, who rated 7 unlabeled breakfast drinks. Liking scores were measured using a 100-mm visual analogue scale, while food-evoked emotions were measured using 2 existing emotion-profiling methods: a verbal and a non-verbal method (EsSense Profile and PrEmo, respectively). After 7 days, participants were asked to choose 1 breakfast drink from the experiment to consume during breakfast in a simulated restaurant environment. Cross validation showed that we were able to correctly predict individualized food choice (1 out of 7 products) for over 50% of the participants. This number increased to nearly 80% when looking at the top 2 candidates. Model comparisons showed that evoked emotions better predict food choice than perceived liking alone. However, the strongest predictive strength was achieved by the combination of evoked emotions and liking. Furthermore we showed that non-verbal food-evoked emotion scores more accurately predict food choice than verbal food-evoked emotions scores.

Short communication: Genetic variation in choice consistency for cows accessing automatic milking units.

PubMed

Løvendahl, Peter; Sørensen, Lars Peter; Bjerring, Martin; Lassen, Jan

2016-12-01

Dairy cows milked in automatic milking systems (AMS) with more than 1 milking box may, as individuals, have a preference for specific milking boxes if allowed free choice. Estimates of quantitative genetic variation in behavioral traits of farmed animals have previously been reported, with estimates of heritability ranging widely. However, for the consistency of choice in dairy cows, almost no published estimates of heritability exist. The hypothesis for this study was that choice consistency is partly under additive genetic control and partly controlled by permanent environmental (animal) effects. The aims of this study were to obtain estimates of genetic and phenotypic parameters for choice consistency in dairy cows milked in AMS herds. Data were obtained from 5 commercial Danish herds (I-V) with 2 AMS milking boxes (A, B). Milking data were only from milkings where both the present and the previous milkings were coded as completed. This filter was used to fulfill a criterion of free-choice situation (713,772 milkings, 1,231 cows). The lactation was divided into 20 segments covering 15d each, from 5 to 305d in milk. Choice consistency scores were obtained as the fraction of milkings without change of box [i.e., 1.0 - µ(box change)] for each segment. Data were analyzed for one part of lactation at a time using a linear mixed model for first-parity cows alone and for all parities jointly. Choice consistency was found to be only weakly heritable (heritability=0.02 to 0.14) in first as well as in later parities, and having intermediate repeatability (repeatability coefficients=0.27 to 0.56). Heritability was especially low at early and late lactation states. These results indicate that consistency, which is itself an indication of repeated similar choices, is also repeatable as a trait observed over longer time periods. However, the genetic background seems to play a smaller role compared with that of the permanent animal effects, indicating that consistency could

Recursive Rational Choice.

DTIC Science & Technology

1981-11-01

that a decision entity acted as though it were making rational choices among a set of alternatives, as a not unreason- able paradigm of human behavior...Gottinger l / , which, like Kramer’s approach, consider the item of rationality in decision making for social decision rules as representable by finite...1974] in the consideration of whether or not a decisive choice function that is regular rational in the sense of Richter [19711 when defined on subsets

Choice as an engine of analytic thought.

PubMed

Savani, Krishna; Stephens, Nicole M; Markus, Hazel Rose

2017-09-01

Choice is a behavioral act that has a variety of well-documented motivational consequences-it fosters independence by allowing people to simultaneously express themselves and influence the environment. Given the link between independence and analytic thinking, the current research tested whether choice also leads people to think in a more analytic rather than holistic manner. Four experiments demonstrate that making choices, recalling choices, and viewing others make choices leads people to think more analytically, as indicated by their attitudes, perceptual judgments, categorization, and patterns of attention allocation. People who made choices scored higher on a subjective self-report measure of analytic cognition compared to whose did not make a choice (pilot study). Using an objective task-based measure, people who recalled choices rather than actions were less influenced by changes in the background when making judgments about focal objects (Experiment 1). People who thought of others' behaviors as choices rather than actions were more likely to group objects based on categories rather than relationships (Experiment 2). People who recalled choices rather than actions subsequently allocated more visual attention to focal objects in a scene (Experiment 3). Together, these experiments demonstrate that choice has important yet previously unexamined consequences for basic psychological processes such as attention and cognition. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Your Genes, Your Choices

MedlinePlus

... Your Choices points out how the progress of science can potentially "invade" your life in the most direct ways, affecting the choices you make at the grocery store, your own health care and that of your family, and ... The connection between science and health is a direct one, and your ...

Combined Uncertainty and A-Posteriori Error Bound Estimates for CFD Calculations: Theory and Implementation

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

2014-01-01

Simulation codes often utilize finite-dimensional approximation resulting in numerical error. Some examples include, numerical methods utilizing grids and finite-dimensional basis functions, particle methods using a finite number of particles. These same simulation codes also often contain sources of uncertainty, for example, uncertain parameters and fields associated with the imposition of initial and boundary data,uncertain physical model parameters such as chemical reaction rates, mixture model parameters, material property parameters, etc.

Choice and conditioned reinforcement.

PubMed Central

Fantino, E; Freed, D; Preston, R A; Williams, W A

1991-01-01

A potential weakness of one formulation of delay-reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal-link stimuli occur in concurrent-chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent-chains schedules or on comparable concurrent-tandem schedules. The initial link was shortened on only one of two concurrent-chains schedules and on only one of two corresponding concurrent-tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay-reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent-chains schedules may have no independent effect on choice. PMID:2037826

The choices before us.

PubMed

Streeten, P P

1980-01-01

This introduction is from the 16th World Conference of SID in Colombo, Sri Lanka, August 1979, which addressed the theme of development choices for the 1980's and beyond. Choices may refer to different political, ideological or social systems. Choices may refer to strategies and technical issues, e.g. agriculture vs. industry. A third meaning of choice is implicit in the idea of a Third World, or alternative, method of development. The third meaning implies a rejection of Western institutions, values, and standards. In the past, the transfer of Western or in this case Northern, institutions and standards has disappointed and created obstacles to development. The rapid rate of population growth forces choices of population control and resource management. Common themes of development have emerged from conference discussions: the need to build development efforts on indigenous values; the need for new institutions both at the sub-national and at the super-national level; and, the need to adjust to inevitable changes rationally and with foresight. The nation state is too large for many functions that are better decentralized and left to village or district administrations, yet it is too small to respond to global challenges and environmental risks like harvest failure, credit risks, marketing risks, failure of supplies. The interests of the state are not identical with those of society or particular groups in society.

Minimal residual method provides optimal regularization parameter for diffuse optical tomography

NASA Astrophysics Data System (ADS)

Jagannath, Ravi Prasad K.; Yalavarthy, Phaneendra K.

2012-10-01

The inverse problem in the diffuse optical tomography is known to be nonlinear, ill-posed, and sometimes under-determined, requiring regularization to obtain meaningful results, with Tikhonov-type regularization being the most popular one. The choice of this regularization parameter dictates the reconstructed optical image quality and is typically chosen empirically or based on prior experience. An automated method for optimal selection of regularization parameter that is based on regularized minimal residual method (MRM) is proposed and is compared with the traditional generalized cross-validation method. The results obtained using numerical and gelatin phantom data indicate that the MRM-based method is capable of providing the optimal regularization parameter.

Minimal residual method provides optimal regularization parameter for diffuse optical tomography.

PubMed

Jagannath, Ravi Prasad K; Yalavarthy, Phaneendra K

2012-10-01

The inverse problem in the diffuse optical tomography is known to be nonlinear, ill-posed, and sometimes under-determined, requiring regularization to obtain meaningful results, with Tikhonov-type regularization being the most popular one. The choice of this regularization parameter dictates the reconstructed optical image quality and is typically chosen empirically or based on prior experience. An automated method for optimal selection of regularization parameter that is based on regularized minimal residual method (MRM) is proposed and is compared with the traditional generalized cross-validation method. The results obtained using numerical and gelatin phantom data indicate that the MRM-based method is capable of providing the optimal regularization parameter.

Transition Choices Program: Preparing To Participate in Life's Choices. Teaching Guide and Curriculum.

ERIC Educational Resources Information Center

Stowitschek, Joseph J.; And Others

The Transition Choices Program (TCP) is designed to increase the ability of young persons with disabilities to participate more fully in the school-to-adult life process through systematic instruction in six skills: exploring choices and developing preferences; planning goals and following through; seeking assistance when needed; recognizing and…

How Many Choices Are Good? Measurement of the Effects of Course Choice on Perceptions of a Marketing Option

ERIC Educational Resources Information Center

Ackerman, David S.; Gross, Barbara L.

2006-01-01

This study examines the effects of amount of choice given students in selecting courses to complete a marketing minor, referred to as a marketing option. It examines how differing levels of choice can affect perceptions of, and feelings about, a marketing option. The course choice process is also explored. The impact of choice on students' desire…

The ABCs of School Choice: The Comprehensive Guide to Every Private School Choice Program in America. 2016 Edition

ERIC Educational Resources Information Center

Friedman Foundation for Educational Choice, 2016

2016-01-01

"The ABCs of School Choice" is a comprehensive, data-rich guide to every private school choice program in America. The 2016 edition of "The ABCs of School Choice" is the best yet, not just because of the new look and the fantastic growth in the number of school choice programs, but also because it is now paired with a…

California's Districts of Choice

ERIC Educational Resources Information Center

Kronholz, June

2014-01-01

This article describes the results of a California state law established in 2010 that created "Districts of Choice." The District of Choice law was meant to encourage districts to compete for students by offering innovative programs and this-school-fits-my-child options that parents wanted. This designation meant that children from any…

The Veterans Choice Program (VCP): Program Implementation

DTIC Science & Technology

2017-01-05

Authorized under Section 101 of the Veterans Access, Choice, and Accountability Act of 2014 (VACAA), the Veterans Choice Program (VCP) is a new...country in spring 2014, 1 Congress passed the Veterans Access, Choice, and Accountability Act of 2014 (VACAA, P.L. 113-146, as amended). On August 7...Veterans Choice Program (VCP) Timeline Date Action August 7, 2014 The Veterans Access, Choice, and Accountability Act of 2014 (P.L. 113-146

The "Tyranny of Choice": Choice Overload as a Possible Instance of Effort Discounting

ERIC Educational Resources Information Center

Reed, Derek D.; Reed, Florence D. DiGennaro; Chok, James; Brozyna, Gary A.

2011-01-01

When making a choice, people like to have options, but an emerging literature on "choice overload" suggests that the provision of too many options results in adverse experiences, including a depletion of cognitive resources and postdecision feelings of regret. A strong implication is that individuals should shy away from situations…

A constrained multinomial Probit route choice model in the metro network: Formulation, estimation and application

PubMed Central

Zhang, Yongsheng; Wei, Heng; Zheng, Kangning

2017-01-01

Considering that metro network expansion brings us with more alternative routes, it is attractive to integrate the impacts of routes set and the interdependency among alternative routes on route choice probability into route choice modeling. Therefore, the formulation, estimation and application of a constrained multinomial probit (CMNP) route choice model in the metro network are carried out in this paper. The utility function is formulated as three components: the compensatory component is a function of influencing factors; the non-compensatory component measures the impacts of routes set on utility; following a multivariate normal distribution, the covariance of error component is structured into three parts, representing the correlation among routes, the transfer variance of route, and the unobserved variance respectively. Considering multidimensional integrals of the multivariate normal probability density function, the CMNP model is rewritten as Hierarchical Bayes formula and M-H sampling algorithm based Monte Carlo Markov Chain approach is constructed to estimate all parameters. Based on Guangzhou Metro data, reliable estimation results are gained. Furthermore, the proposed CMNP model also shows a good forecasting performance for the route choice probabilities calculation and a good application performance for transfer flow volume prediction. PMID:28591188

Connecting cognition and consumer choice.

PubMed

Bartels, Daniel M; Johnson, Eric J

2015-02-01

We describe what can be gained from connecting cognition and consumer choice by discussing two contexts ripe for interaction between the two fields. The first-context effects on choice-has already been addressed by cognitive science yielding insights about cognitive process but there is promise for more interaction. The second is learning and representation in choice where relevant theories in cognitive science could be informed by consumer choice, and in return, could pose and answer new questions. We conclude by discussing how these two fields of research stand to benefit from more interaction, citing examples of how interfaces of cognitive science with other fields have been illuminating for theories of cognition. Copyright © 2014 Elsevier B.V. All rights reserved.

Proceedings--symposium on recreation choice behavior

Treesearch

George H. Stankey; Stephen F. McCool

1985-01-01

Presents an overview paper and 11 contributed papers focused on the issue of the processes that underlie decision making by recreationists. The papers span a range of topics including the theory of choice behavior, empirical investigations of choice, and methodological approaches to the study of choice behavior.

Determinants of Career Choice in Women.

ERIC Educational Resources Information Center

Gutek, Barbara A.; Nieva, Veronica F.

1979-01-01

Societal attitudes, parental attitudes, and young women's abilities and interests and how they affect their choices of careers are examined. Attitudes toward sex-role appropriateness of occupations, women's anticipated career choices, career pioneers, masculinity v femininity, intrinsic v extrinsic job rewards, time of choice, and predictors of…

Behavioural social choice: a status report.

PubMed

Regenwetter, Michel; Grofman, Bernard; Popova, Anna; Messner, William; Davis-Stober, Clintin P; Cavagnaro, Daniel R

2009-03-27

Behavioural social choice has been proposed as a social choice parallel to seminal developments in other decision sciences, such as behavioural decision theory, behavioural economics, behavioural finance and behavioural game theory. Behavioural paradigms compare how rational actors should make certain types of decisions with how real decision makers behave empirically. We highlight that important theoretical predictions in social choice theory change dramatically under even minute violations of standard assumptions. Empirical data violate those critical assumptions. We argue that the nature of preference distributions in electorates is ultimately an empirical question, which social choice theory has often neglected. We also emphasize important insights for research on decision making by individuals. When researchers aggregate individual choice behaviour in laboratory experiments to report summary statistics, they are implicitly applying social choice rules. Thus, they should be aware of the potential for aggregation paradoxes. We hypothesize that such problems may substantially mar the conclusions of a number of (sometimes seminal) papers in behavioural decision research.

Neural correlates of affective influence on choice.

PubMed

Piech, Richard M; Lewis, Jade; Parkinson, Caroline H; Owen, Adrian M; Roberts, Angela C; Downing, Paul E; Parkinson, John A

2010-03-01

Making the right choice depends crucially on the accurate valuation of the available options in the light of current needs and goals of an individual. Thus, the valuation of identical options can vary considerably with motivational context. The present study investigated the neural structures underlying context dependent evaluation. We instructed participants to choose from food menu items based on different criteria: on their anticipated taste or on ease of preparation. The aim of the manipulation was to assess which neural sites were activated during choice guided by incentive value, and which during choice based on a value-irrelevant criterion. To assess the impact of increased motivation, affect-guided choice and cognition-guided choice was compared during the sated and hungry states. During affective choice, we identified increased activity in structures representing primarily valuation and taste (medial prefrontal cortex, insula). During cognitive choice, structures showing increased activity included those implicated in suppression and conflict monitoring (lateral orbitofrontal cortex, anterior cingulate). Hunger influenced choice-related activity in the ventrolateral prefrontal cortex. Our results show that choice is associated with the use of distinct neural structures for the pursuit of different goals. Published by Elsevier Inc.

Kinetics of Aggregation with Choice

DOE PAGES

Ben-Naim, Eli; Krapivsky, Paul

2016-12-01

Here we generalize the ordinary aggregation process to allow for choice. In ordinary aggregation, two random clusters merge and form a larger aggregate. In our implementation of choice, a target cluster and two candidate clusters are randomly selected and the target cluster merges with the larger of the two candidate clusters.We study the long-time asymptotic behavior and find that as in ordinary aggregation, the size density adheres to the standard scaling form. However, aggregation with choice exhibits a number of different features. First, the density of the smallest clusters exhibits anomalous scaling. Second, both the small-size and the large-size tailsmore » of the density are overpopulated, at the expense of the density of moderate-size clusters. Finally, we also study the complementary case where the smaller candidate cluster participates in the aggregation process and find an abundance of moderate clusters at the expense of small and large clusters. Additionally, we investigate aggregation processes with choice among multiple candidate clusters and a symmetric implementation where the choice is between two pairs of clusters.« less

The Role of Aspiration Level in Risky Choice: A Comparison of Cumulative Prospect Theory and SP/A Theory.

PubMed

Lopes; Oden

1999-06-01

In recent years, descriptive models of risky choice have incorporated features that reflect the importance of particular outcome values in choice. Cumulative prospect theory (CPT) does this by inserting a reference point in the utility function. SP/A (security-potential/aspiration) theory uses aspiration level as a second criterion in the choice process. Experiment 1 compares the ability of the CPT and SP/A models to account for the same within-subjects data set and finds in favor of SP/A. Experiment 2 replicates the main finding of Experiment 1 in a between-subjects design. The final discussion brackets the SP/A result by showing the impact on fit of both decreasing and increasing the number of free parameters. We also suggest how the SP/A approach might be useful in modeling investment decision making in a descriptively more valid way and conclude with comments on the relation between descriptive and normative theories of risky choice. Copyright 1999 Academic Press.

Similar Performance, but Different Choices: Social Class and Higher Education Choice in Greece

ERIC Educational Resources Information Center

Sianou-Kyrgiou, Eleni; Tsiplakides, Iakovos

2011-01-01

Higher education choice has been a central theme in sociological research in recent decades, especially following the policies for the widening of participation adopted in many countries. Research has shown a relationship between social class and higher education choice, and this is a reason why the expansion of higher education does not reduce…

School Choice in a Post-Desegregation World

ERIC Educational Resources Information Center

Cobb, Casey D.; Glass, Gene V.

2009-01-01

In contrast to unregulated school choice, regulated choice programs oversee the assignment of students to schools with equity in mind. This article puts forth evidence for three claims with respect to unregulated and regulated school choice: (c) Unregulated choice plans tend to exacerbate the stratification of students along race, class, and…

Optimization of digital breast tomosynthesis (DBT) acquisition parameters for human observers: effect of reconstruction algorithms

NASA Astrophysics Data System (ADS)

Zeng, Rongping; Badano, Aldo; Myers, Kyle J.

2017-04-01

We showed in our earlier work that the choice of reconstruction methods does not affect the optimization of DBT acquisition parameters (angular span and number of views) using simulated breast phantom images in detecting lesions with a channelized Hotelling observer (CHO). In this work we investigate whether the model-observer based conclusion is valid when using humans to interpret images. We used previously generated DBT breast phantom images and recruited human readers to find the optimal geometry settings associated with two reconstruction algorithms, filtered back projection (FBP) and simultaneous algebraic reconstruction technique (SART). The human reader results show that image quality trends as a function of the acquisition parameters are consistent between FBP and SART reconstructions. The consistent trends confirm that the optimization of DBT system geometry is insensitive to the choice of reconstruction algorithm. The results also show that humans perform better in SART reconstructed images than in FBP reconstructed images. In addition, we applied CHOs with three commonly used channel models, Laguerre-Gauss (LG) channels, square (SQR) channels and sparse difference-of-Gaussian (sDOG) channels. We found that LG channels predict human performance trends better than SQR and sDOG channel models for the task of detecting lesions in tomosynthesis backgrounds. Overall, this work confirms that the choice of reconstruction algorithm is not critical for optimizing DBT system acquisition parameters.

Improved discriminability of spatiotemporal neural patterns in rat motor cortical areas as directional choice learning progresses

PubMed Central

Mao, Hongwei; Yuan, Yuan; Si, Jennie

2015-01-01

Animals learn to choose a proper action among alternatives to improve their odds of success in food foraging and other activities critical for survival. Through trial-and-error, they learn correct associations between their choices and external stimuli. While a neural network that underlies such learning process has been identified at a high level, it is still unclear how individual neurons and a neural ensemble adapt as learning progresses. In this study, we monitored the activity of single units in the rat medial and lateral agranular (AGm and AGl, respectively) areas as rats learned to make a left or right side lever press in response to a left or right side light cue. We noticed that rat movement parameters during the performance of the directional choice task quickly became stereotyped during the first 2–3 days or sessions. But learning the directional choice problem took weeks to occur. Accompanying rats' behavioral performance adaptation, we observed neural modulation by directional choice in recorded single units. Our analysis shows that ensemble mean firing rates in the cue-on period did not change significantly as learning progressed, and the ensemble mean rate difference between left and right side choices did not show a clear trend of change either. However, the spatiotemporal firing patterns of the neural ensemble exhibited improved discriminability between the two directional choices through learning. These results suggest a spatiotemporal neural coding scheme in a motor cortical neural ensemble that may be responsible for and contributing to learning the directional choice task. PMID:25798093

Making School Choice Work

ERIC Educational Resources Information Center

DeArmond, Michael; Jochim, Ashley; Lake, Robin

2014-01-01

School choice is increasingly the new normal in urban education. But in cities with multiple public school options, how can civic leaders create a choice system that works for all families, whether they choose a charter or district public school? To answer this question, the Center on Reinventing Public Education (CRPE) researchers surveyed 4,000…

School Choice Marches forward

ERIC Educational Resources Information Center

Butcher, Jonathan

2013-01-01

One year ago, the "Wall Street Journal" dubbed 2011 "the year of school choice," opining that "this year is shaping up as the best for reformers in a very long time." School-choice laws took great strides in 2011, both in the number of programs that succeeded across states and also in the size and scope of the adopted…

Customer Choice Would Advance Renewable Energy

Science.gov Websites

Customer Choice Would Advance Renewable Energy Golden, Colo., Oct. 31, 2001 Giving consumers a , but the recent suspension of customer choice in California represents a setback to the development of of market rules and public policies that support customer choice. The full report, "Forecasting

Safer Choice

EPA Pesticide Factsheets

Safer Choice is a voluntary program that works to advance the mission of EPA to protect human health and the environment by helping product manufacturers choose the safest chemical ingredients possible.

The Additive Effects of Choice and Control.

ERIC Educational Resources Information Center

Karbowski, Joseph; And Others

In separate research studies, students who were given a choice of learning materials or who had control over aversive noise, demonstrated higher motivation and better task performance. To investigate the additive effects of choice and control on perception of control, 80 male and female college students participated in a 2 (choice vs. no-choice) X…

School Choice Acceptance: An Exploratory Explication

ERIC Educational Resources Information Center

Koven, Steven G.; Khan, Mobin

2014-01-01

School choice is presented by some as a panacea to the challenges facing education in the United States. Acceptance of choice as a solution, however, is far from universal. This article examines two possible contributors to choice adoption: ideology and political culture. Political culture was found to better explain the complex phenomenon of…

Merging Psychophysical and Psychometric Theory to Estimate Global Visual State Measures from Forced-Choices

NASA Astrophysics Data System (ADS)

Massof, Robert W.; Schmidt, Karen M.; Laby, Daniel M.; Kirschen, David; Meadows, David

2013-09-01

Visual acuity, a forced-choice psychophysical measure of visual spatial resolution, is the sine qua non of clinical visual impairment testing in ophthalmology and optometry patients with visual system disorders ranging from refractive error to retinal, optic nerve, or central visual system pathology. Visual acuity measures are standardized against a norm, but it is well known that visual acuity depends on a variety of stimulus parameters, including contrast and exposure duration. This paper asks if it is possible to estimate a single global visual state measure from visual acuity measures as a function of stimulus parameters that can represent the patient's overall visual health state with a single variable. Psychophysical theory (at the sensory level) and psychometric theory (at the decision level) are merged to identify the conditions that must be satisfied to derive a global visual state measure from parameterised visual acuity measures. A global visual state measurement model is developed and tested with forced-choice visual acuity measures from 116 subjects with no visual impairments and 560 subjects with uncorrected refractive error. The results are in agreement with the expectations of the model.

Research on Bounded Rationality of Fuzzy Choice Functions

PubMed Central

Wu, Xinlin; Zhao, Yong

2014-01-01

The rationality of a fuzzy choice function is a hot research topic in the study of fuzzy choice functions. In this paper, two common fuzzy sets are studied and analyzed in the framework of the Banerjee choice function. The complete rationality and bounded rationality of fuzzy choice functions are defined based on the two fuzzy sets. An assumption is presented to study the fuzzy choice function, and especially the fuzzy choice function with bounded rationality is studied combined with some rationality conditions. Results show that the fuzzy choice function with bounded rationality also satisfies some important rationality conditions, but not vice versa. The research gives supplements to the investigation in the framework of the Banerjee choice function. PMID:24782677

Research on bounded rationality of fuzzy choice functions.

PubMed

Wu, Xinlin; Zhao, Yong

2014-01-01

The rationality of a fuzzy choice function is a hot research topic in the study of fuzzy choice functions. In this paper, two common fuzzy sets are studied and analyzed in the framework of the Banerjee choice function. The complete rationality and bounded rationality of fuzzy choice functions are defined based on the two fuzzy sets. An assumption is presented to study the fuzzy choice function, and especially the fuzzy choice function with bounded rationality is studied combined with some rationality conditions. Results show that the fuzzy choice function with bounded rationality also satisfies some important rationality conditions, but not vice versa. The research gives supplements to the investigation in the framework of the Banerjee choice function.

Propulsion System Choices and Their Implications

NASA Technical Reports Server (NTRS)

Joyner, Claude R., II; Levack, Daniel J. H.; Rhodes, Russell, E.; Robinson, John W.

2010-01-01

In defining a space vehicle architecture, the propulsion system and related subsystem choices will have a major influence on achieving the goals and objectives desired. There are many alternatives and the choices made must produce a system that meets the performance requirements, but at the same time also provide the greatest opportunity of reaching all of the required objectives. Recognizing the above, the SPST Functional Requirements subteam has drawn on the knowledge, expertise, and experience of its members, to develop insight that wiIJ effectively aid the architectural concept developer in making the appropriate choices consistent with the architecture goals. This data not only identifies many selected choices, but also, more importantly, presents the collective assessment of this subteam on the "pros" and the "cons" of these choices. The propulsion system choices with their pros and cons are presented in five major groups. A. System Integration Approach. Focused on the requirement for safety, reliability, dependability, maintainability, and low cost. B. Non-Chemical Propulsion. Focused on choice of propulsion type. C. Chemical Propulsion. Focused on propellant choice implications. D. Functional Integration. Focused on the degree of integration of the many propulsive and closely associated functions, and on the choice of the engine combustion power cycle. E. Thermal Management. Focused on propellant tank insulation and integration. Each of these groups is further broken down into subgroups, and at that level the consensus pros and cons are presented. The intended use of this paper is to provide a resource of focused material for architectural concept developers to use in designing new advanced systems including college design classes. It is also a possible source of input material for developing a model for designing and analyzing advanced concepts to help identify focused technology needs and their priorities.

Stochastic Technology Choice Model for Consequential Life Cycle Assessment.

PubMed

Kätelhön, Arne; Bardow, André; Suh, Sangwon

2016-12-06

Discussions on Consequential Life Cycle Assessment (CLCA) have relied largely on partial or general equilibrium models. Such models are useful for integrating market effects into CLCA, but also have well-recognized limitations such as the poor granularity of the sectoral definition and the assumption of perfect oversight by all economic agents. Building on the Rectangular-Choice-of-Technology (RCOT) model, this study proposes a new modeling approach for CLCA, the Technology Choice Model (TCM). In this approach, the RCOT model is adapted for its use in CLCA and extended to incorporate parameter uncertainties and suboptimal decisions due to market imperfections and information asymmetry in a stochastic setting. In a case study on rice production, we demonstrate that the proposed approach allows modeling of complex production technology mixes and their expected environmental outcomes under uncertainty, at a high level of detail. Incorporating the effect of production constraints, uncertainty, and suboptimal decisions by economic agents significantly affects technology mixes and associated greenhouse gas (GHG) emissions of the system under study. The case study also shows the model's ability to determine both the average and marginal environmental impacts of a product in response to changes in the quantity of final demand.

Manipulations of Choice Familiarity in Multiple-Choice Testing Support a Retrieval Practice Account of the Testing Effect

ERIC Educational Resources Information Center

Jang, Yoonhee; Pashler, Hal; Huber, David E.

2014-01-01

We performed 4 experiments assessing the learning that occurs when taking a test. Our experiments used multiple-choice tests because the processes deployed during testing can be manipulated by varying the nature of the choice alternatives. Previous research revealed that a multiple-choice test that includes "none of the above" (NOTA)…

Vocational Choice: A Decision Making Perspective

ERIC Educational Resources Information Center

Sauermann, Henry

2005-01-01

We propose a model of vocational choice that can be used for analyzing and guiding the decision processes underlying career and job choices. Our model is based on research in behavioral decision making (BDM), in particular the choice goals framework developed by Bettman, Luce, and Payne (1998). The basic model involves two major processes. First,…

School Choice as a Bounded Ideal

ERIC Educational Resources Information Center

Ben-Porath, Sigal R.

2009-01-01

School choice is most often viewed through the lens of provision: most of the debate on the issue searches for desirable ways to offer vouchers, scholarships or other tools that provides choice as a way to achieve equality and/or freedom. This paper focuses on the consumer side of school choice, and utilises behavioural economics as well as…

Choice within Constraints: Mothers and Schooling.

ERIC Educational Resources Information Center

David, Miriam; Davies, Jackie; Edwards, Rosalind; Reay, Diane; Standing, Kay

1997-01-01

Explores, from a feminist perspective, the discourses of choice regarding how women make their choices as consumers in the education marketplace. It argues that mothers as parents are not free to choose but act within a range of constraints, i.e., their choices are limited by structural and moral possibilities in a patriarchal and racist society.…

Examining a Thermodynamic Order Parameter of Protein Folding.

PubMed

Chong, Song-Ho; Ham, Sihyun

2018-05-08

Dimensionality reduction with a suitable choice of order parameters or reaction coordinates is commonly used for analyzing high-dimensional time-series data generated by atomistic biomolecular simulations. So far, geometric order parameters, such as the root mean square deviation, fraction of native amino acid contacts, and collective coordinates that best characterize rare or large conformational transitions, have been prevailing in protein folding studies. Here, we show that the solvent-averaged effective energy, which is a thermodynamic quantity but unambiguously defined for individual protein conformations, serves as a good order parameter of protein folding. This is illustrated through the application to the folding-unfolding simulation trajectory of villin headpiece subdomain. We rationalize the suitability of the effective energy as an order parameter by the funneledness of the underlying protein free energy landscape. We also demonstrate that an improved conformational space discretization is achieved by incorporating the effective energy. The most distinctive feature of this thermodynamic order parameter is that it works in pointing to near-native folded structures even when the knowledge of the native structure is lacking, and the use of the effective energy will also find applications in combination with methods of protein structure prediction.

Identifying uniformly mutated segments within repeats.

PubMed

Sahinalp, S Cenk; Eichler, Evan; Goldberg, Paul; Berenbrink, Petra; Friedetzky, Tom; Ergun, Funda

2004-12-01

Given a long string of characters from a constant size alphabet we present an algorithm to determine whether its characters have been generated by a single i.i.d. random source. More specifically, consider all possible n-coin models for generating a binary string S, where each bit of S is generated via an independent toss of one of the n coins in the model. The choice of which coin to toss is decided by a random walk on the set of coins where the probability of a coin change is much lower than the probability of using the same coin repeatedly. We present a procedure to evaluate the likelihood of a n-coin model for given S, subject a uniform prior distribution over the parameters of the model (that represent mutation rates and probabilities of copying events). In the absence of detailed prior knowledge of these parameters, the algorithm can be used to determine whether the a posteriori probability for n=1 is higher than for any other n>1. Our algorithm runs in time O(l4logl), where l is the length of S, through a dynamic programming approach which exploits the assumed convexity of the a posteriori probability for n. Our test can be used in the analysis of long alignments between pairs of genomic sequences in a number of ways. For example, functional regions in genome sequences exhibit much lower mutation rates than non-functional regions. Because our test provides means for determining variations in the mutation rate, it may be used to distinguish functional regions from non-functional ones. Another application is in determining whether two highly similar, thus evolutionarily related, genome segments are the result of a single copy event or of a complex series of copy events. This is particularly an issue in evolutionary studies of genome regions rich with repeat segments (especially tandemly repeated segments).

Final Report of Project CHOICE: A Center for Helping Organizations Improve Choice in Education.

ERIC Educational Resources Information Center

Chapman, Davis W.; And Others

The purpose of the Center for Helping Organizations Improve Choice in Education (CHOICE) project, the scope of its activities, and evaluations of the effectiveness of those activities are described. One major project goal was to encourage and facilitate institutional efforts to provide more complete and accurate information to prospective…

Imposition of physical parameters in dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Mai-Duy, N.; Phan-Thien, N.; Tran-Cong, T.

2017-12-01

In the mesoscale simulations by the dissipative particle dynamics (DPD), the motion of a fluid is modelled by a set of particles interacting in a pairwise manner, and it has been shown to be governed by the Navier-Stokes equation, with its physical properties, such as viscosity, Schmidt number, isothermal compressibility, relaxation and inertia time scales, in fact its whole rheology resulted from the choice of the DPD model parameters. In this work, we will explore the response of a DPD fluid with respect to its parameter space, where the model input parameters can be chosen in advance so that (i) the ratio between the relaxation and inertia time scales is fixed; (ii) the isothermal compressibility of water at room temperature is enforced; and (iii) the viscosity and Schmidt number can be specified as inputs. These impositions are possible with some extra degrees of freedom in the weighting functions for the conservative and dissipative forces. Numerical experiments show an improvement in the solution quality over conventional DPD parameters/weighting functions, particularly for the number density distribution and computed stresses.

14 CFR 1214.117 - Launch and orbit parameters for a standard launch.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Launch from Kennedy Space Center (KSC) into the customer's choice of two standard mission orbits: 160 NM... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Launch and orbit parameters for a standard launch. 1214.117 Section 1214.117 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...

14 CFR 1214.117 - Launch and orbit parameters for a standard launch.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Launch from Kennedy Space Center (KSC) into the customer's choice of two standard mission orbits: 160 NM... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Launch and orbit parameters for a standard launch. 1214.117 Section 1214.117 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...

14 CFR 1214.117 - Launch and orbit parameters for a standard launch.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Launch from Kennedy Space Center (KSC) into the customer's choice of two standard mission orbits: 160 NM... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Launch and orbit parameters for a standard launch. 1214.117 Section 1214.117 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...

Brain microstructural correlates of visuospatial choice reaction time in children.

PubMed

Madsen, Kathrine Skak; Baaré, William F C; Skimminge, Arnold; Vestergaard, Martin; Siebner, Hartwig R; Jernigan, Terry L

2011-10-15

The corticospinal tracts and the basal ganglia continue to develop during childhood and adolescence, and indices of their maturation can be obtained using diffusion-weighted imaging. Here we show that a simple measure of visuomotor function is correlated with diffusion parameters in the corticospinal tracts and neostriatum. In a cohort of 75 typically-developing children aged 7 to 13years, mean 5-choice reaction times (RTs) were assessed. We hypothesised that children with faster choice RTs would show lower mean diffusivity (MD) in the corticospinal tracts and neostriatum and higher fractional anisotropy (FA) in the corticospinal tracts, after controlling for age, gender, and handedness. Mean MD and/or FA were extracted from the right and left corticospinal tracts, putamen, and caudate nuclei. As predicted, faster 5-choice RTs were associated with lower MD in the corticospinal tracts, putamen, and caudate. MD effects on RT were bilateral in the corticospinal tracts and putamen, whilst right caudate MD was more strongly related to performance than was left caudate MD. Our results suggest a link between motor performance variability in children and diffusivity in the motor system, which may be related to: individual differences in the phase of fibre tract and neostriatal maturation in children of similar age, individual differences in motor experience during childhood (i.e., use-dependent plasticity), and/or more stable individual differences in the architecture of the motor system. Copyright © 2011 Elsevier Inc. All rights reserved.

Think twice before you book? Modelling the choice of public vs private dentist in a choice experiment.

PubMed

Kiiskinen, Urpo; Suominen-Taipale, Anna Liisa; Cairns, John

2010-06-01

This study concerns the choice of primary dental service provider by consumers. If the health service delivery system allows individuals to choose between public-care providers or if complementary private services are available, it is typically assumed that utilisation is a three-stage decision process. The patient first makes a decision to seek care, and then chooses the service provider. The final stage, involving decisions over the amount and form of treatment, is not considered here. The paper reports a discrete choice experiment (DCE) designed to evaluate attributes affecting individuals' choice of dental-care provider. The feasibility of the DCE approach in modelling consumers' choice in the context of non-acute need for dental care is assessed. The aim is to test whether a separate two-stage logit, a multinomial logit, or a nested logit best fits the choice process of consumers. A nested logit model of indirect utility functions is estimated and inclusive value (IV) constraints are tested for modelling implications. The results show that non-trading behaviour has an impact on the choice of appropriate modelling technique, but is to some extent dependent on the choice of scenarios offered. It is concluded that for traders multinomial logit is appropriate, whereas for non-traders and on average the nested logit is the method supported by the analyses. The consistent finding in all subgroup analyses is that the traditional two-stage decision process is found to be implausible in the context of consumer's choice of dental-care provider.

Lack of behavioural evidence for kin avoidance in mate choice in a hymenopteran parasitoid (Hymenoptera: Braconidae).

PubMed

Bourdais, D; Hance, T

2009-05-01

Mechanisms for inbreeding avoidance should be prevalent in insects that reproduce by arrhenotokous haplodiploidy because of the higher potential production of unviable diploid males in inbred matings. Few studies have focused on mating strategies in insect parasitoids and even less on kinship relationships during mate choice. In this study we tested avoidance of kin as mate in the parasitic wasp Aphidius matricariae (Hymenoptera: Braconidae) using an ethological approach. Key mating parameters, such as male wing fanning, latent period before genitalia contact and duration of copulation were measured. No evidence for kin avoidance in mate choice in both A. matricariae males and females was observed in our behaviour (no choice or choice tests) tests. This lack of ethological sib mating avoidance could be due to different factors such as sex determination rule different than the single locus complementary sex determination, making lower the proportion of diploid males in case of sib matings and thus its negative consequence. The existence of other inbreeding avoidance strategies and mechanisms that reduce the probability of 2 receptive relatives meeting in nature may be common, for example, inbred mating may be rare through differential dispersal, delayed maturation, or protandry.

Evaluating the Concept of Choice in Healthcare

PubMed Central

Zolkefli, Yusrita

2017-01-01

Choice is what we all want, as most would say. There is a growing cognisance that patients can and should play an important role in deciding their own care, in defining optimal care, and in improving healthcare delivery. Popular concepts such as patient-centred care, patient empowerment, and patients as partners, shared decision making, and informed choice illustrate the emancipation of patient. The paper describes that choice is not necessarily a good thing in health care; however, that does not rebut the significance of choice. In order to support the overall argument, the paper focuses on why patient choice is important, and in each discussion, this is disputed with counter-arguments to demonstrate that in fact, to an extent, choice is not necessarily a good thing in healthcare. PMID:29379391

Making Poor Choices? Demand Rationalities and School Choice in a Chilean Local Education Market

ERIC Educational Resources Information Center

Bonal, Xavier; Verger, Antoni; Zancajo, Adrián

2017-01-01

Although the literature on school choice rationalities is extensive, different authors interpret the processes of school choice for poor families in different ways. Positions vary between those that consider that poor families have the same capacity to choose as middle class families and those that value structural factors as constraints for…

The Neuroscience of Consumer Choice

PubMed Central

Hsu, Ming; Yoon, Carolyn

2015-01-01

We review progress and challenges relating to scientific and applied goals of the nascent field of consumer neuroscience. Scientifically, substantial progress has been made in understanding the neurobiology of choice processes. Further advances, however, require researchers to begin clarifying the set of developmental and cognitive processes that shape and constrain choices. First, despite the centrality of preferences in theories of consumer choice, we still know little about where preferences come from and the underlying developmental processes. Second, the role of attention and memory processes in consumer choice remains poorly understood, despite importance ascribed to them in interpreting data from the field. The applied goal of consumer neuroscience concerns our ability to translate this understanding to augment prediction at the population level. Although the use of neuroscientific data for market-level predictions remains speculative, there is growing evidence of superiority in specific cases over existing market research techniques. PMID:26665152

Analysis Test of Understanding of Vectors with the Three-Parameter Logistic Model of Item Response Theory and Item Response Curves Technique

ERIC Educational Resources Information Center

Rakkapao, Suttida; Prasitpong, Singha; Arayathanitkul, Kwan

2016-01-01

This study investigated the multiple-choice test of understanding of vectors (TUV), by applying item response theory (IRT). The difficulty, discriminatory, and guessing parameters of the TUV items were fit with the three-parameter logistic model of IRT, using the parscale program. The TUV ability is an ability parameter, here estimated assuming…

Sad Facial Expressions Increase Choice Blindness

PubMed Central

Wang, Yajie; Zhao, Song; Zhang, Zhijie; Feng, Wenfeng

2018-01-01

Previous studies have discovered a fascinating phenomenon known as choice blindness—individuals fail to detect mismatches between the face they choose and the face replaced by the experimenter. Although previous studies have reported a couple of factors that can modulate the magnitude of choice blindness, the potential effect of facial expression on choice blindness has not yet been explored. Using faces with sad and neutral expressions (Experiment 1) and faces with happy and neutral expressions (Experiment 2) in the classic choice blindness paradigm, the present study investigated the effects of facial expressions on choice blindness. The results showed that the detection rate was significantly lower on sad faces than neutral faces, whereas no significant difference was observed between happy faces and neutral faces. The exploratory analysis of verbal reports found that participants who reported less facial features for sad (as compared to neutral) expressions also tended to show a lower detection rate of sad (as compared to neutral) faces. These findings indicated that sad facial expressions increased choice blindness, which might have resulted from inhibition of further processing of the detailed facial features by the less attractive sad expressions (as compared to neutral expressions). PMID:29358926

Sad Facial Expressions Increase Choice Blindness.

PubMed

Wang, Yajie; Zhao, Song; Zhang, Zhijie; Feng, Wenfeng

2017-01-01

Previous studies have discovered a fascinating phenomenon known as choice blindness-individuals fail to detect mismatches between the face they choose and the face replaced by the experimenter. Although previous studies have reported a couple of factors that can modulate the magnitude of choice blindness, the potential effect of facial expression on choice blindness has not yet been explored. Using faces with sad and neutral expressions (Experiment 1) and faces with happy and neutral expressions (Experiment 2) in the classic choice blindness paradigm, the present study investigated the effects of facial expressions on choice blindness. The results showed that the detection rate was significantly lower on sad faces than neutral faces, whereas no significant difference was observed between happy faces and neutral faces. The exploratory analysis of verbal reports found that participants who reported less facial features for sad (as compared to neutral) expressions also tended to show a lower detection rate of sad (as compared to neutral) faces. These findings indicated that sad facial expressions increased choice blindness, which might have resulted from inhibition of further processing of the detailed facial features by the less attractive sad expressions (as compared to neutral expressions).

Consumers, health insurance and dominated choices.

PubMed

Sinaiko, Anna D; Hirth, Richard A

2011-03-01

We analyze employee health plan choices when the choice set offered by their employer includes a dominated plan. During our study period, one-third of workers were enrolled in the dominated plan. Some may have selected the plan before it was dominated and then failed to switch out of it. However, a substantial number actively chose the dominated plan when they had an unambiguously better choice. These results suggest limitations in the ability of health reform based solely on consumer choice to achieve efficient outcomes and that implementation of health reform should anticipate, monitor and account for this consumer behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

'Good genes as heterozygosity': the major histocompatibility complex and mate choice in Atlantic salmon (Salmo salar).

PubMed

Landry, C; Garant, D; Duchesne, P; Bernatchez, L

2001-06-22

According to the theory of mate choice based on heterozygosity, mates should choose each other in order to increase the heterozygosity of their offspring. In this study, we tested the 'good genes as heterozygosity' hypothesis of mate choice by documenting the mating patterns of wild Atlantic salmon (Salmo salar) using both major histocompatibility complex (MHC) and microsatellite loci. Specifically, we tested the null hypotheses that mate choice in Atlantic salmon is not dependent on the relatedness between potential partners or on the MHC similarity between mates. Three parameters were assessed: (i) the number of shared alleles between partners (x and y) at the MHC (M(xy)), (ii) the MHC amino-acid genotypic distance between mates' genotypes (AA(xy)), and (iii) genetic relatedness between mates (r(xy)). We found that Atlantic salmon choose their mates in order to increase the heterozygosity of their offspring at the MHC and, more specifically, at the peptide-binding region, presumably in order to provide them with better defence against parasites and pathogens. This was supported by a significant difference between the observed and expected AA(xy) (p = 0.0486). Furthermore, mate choice was not a mechanism of overall inbreeding avoidance as genetic relatedness supported a random mating scheme (p = 0.445). This study provides the first evidence that MHC genes influence mate choice in fish.

Educational Choice. A Background Paper.

ERIC Educational Resources Information Center

Quality Education for Minorities Network, Washington, DC.

This paper addresses school choice, one proposal to address parental involvement concerns, focusing on historical background, definitions, rationale for advocating choice, implementation strategies, and implications for minorities and low-income families. In the past, transfer payment programs such as tuition tax credits and vouchers were…

TCP performance in ATM networks: ABR parameter tuning and ABR/UBR comparisons

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

Chien Fang; Lin, A.

1996-02-27

This paper explores two issues on TOP performance over ATM networks: ABR parameter tuning and performance comparison of binary mode ABR with enhanced UBR services. Of the fifteen parameters defined for ABR, two parameters dominate binary mode ABR performance: Rate Increase Factor (RIF) and Rate Decrease Factor (RDF). Using simulations, we study the effects of these two parameters on TOP over ABR performance. We compare TOP performance with different ABR parameter settings in terms of through-puts and fairness. The effects of different buffer sizes and LAN/WAN distances are also examined. We then compare TOP performance with the best ABR parametermore » setting with corresponding UBR service enhanced with Early Packet Discard and also with a fair buffer allocation scheme. The results show that TOP performance over binary mode ABR is very sensitive to parameter value settings, and that a poor choice of parameters can result in ABR performance worse than that of the much less expensive UBR-EPD scheme.« less

Diet choice, cortisol reactivity, and emotional feeding in socially housed rhesus monkeys.

PubMed

Arce, Marilyn; Michopoulos, Vasiliki; Shepard, Kathryn N; Ha, Quynh-Chau; Wilson, Mark E

2010-11-02

Chronic psychosocial stress produces an array of adverse health consequences that are highly comorbid, including emotional eating, affective disorders, and metabolic syndrome. The consumption of high caloric diets (HCDs) is thought to provide comfort in the face of unrelenting psychosocial stress. Using social subordination in female rhesus monkeys as a model of continual exposure to daily stressors in women, we tested the hypothesis that subordinate females would consume significantly more calories from a HCD compared to dominant females, and this pattern of food intake would be associated with reduced cortisol release and reduced frequency of anxiety-like behaviors. Food intake, parameters of cortisol secretion, and socio-emotional behavior were assessed for 3 weeks during a no choice phase when only a low caloric diet (LCD) was available and during a choice condition when both a LCD and HCD were available. While all animals preferred the HCD, subordinate females consumed significantly more of the HCD than did dominant females. A flattening of the diurnal cortisol rhythm and a greater increase in serum cortisol to an acute social separation occurred during the diet choice condition in all females. Furthermore, the rate of anxiety-like behavior progressively declined during the 3-week choice condition in subordinate but not dominant females. These data provide support for the hypothesis that daily exposure to psychosocial stress increases consumption of calorically dense foods. Furthermore, consumption of HCDs may be a metabolic stressor that synergizes with the psychosocial stress of subordination to further increase the consumption of these diets. Copyright © 2010 Elsevier Inc. All rights reserved.

I'm no longer torn after choice: how explicit choices implicitly shape preferences of odors.

PubMed

Coppin, Géraldine; Delplanque, Sylvain; Cayeux, Isabelle; Porcherot, Christelle; Sander, David

2010-04-01

Several studies have shown that preferences can be strongly modulated by cognitive processes such as decision making and choices. However, it is still unclear whether choices can influence preferences of sensory stimuli implicitly. This question was addressed here by asking participants to evaluate odors, to choose their preferred odors within pairs, to reevaluate the odors, and to perform an unexpected memory test. Results revealed, for the first time in the study of olfaction, the existence of postchoice preference changes, in the sense of an overvaluation of chosen odors and a devaluation of rejected ones, even when choices were forgotten. These results suggest that chemosensory preferences can be modulated by explicit choices and that such modulation might rely on implicit mechanisms. This finding rules out any explanation of postchoice preference changes in terms of experimental demand and strongly challenges the classical cognitive-dissonance-reduction account of such preference changes.

On selecting satellite conjunction filter parameters

NASA Astrophysics Data System (ADS)

Alfano, Salvatore; Finkleman, David

2014-06-01

This paper extends concepts of signal detection theory to predict the performance of conjunction screening techniques and guiding the selection of keepout and screening thresholds. The most efficient way to identify satellites likely to collide is to employ filters to identify orbiting pairs that should not come close enough over a prescribed time period to be considered hazardous. Such pairings can then be eliminated from further computation to accelerate overall processing time. Approximations inherent in filtering techniques include screening using only unperturbed Newtonian two body astrodynamics and uncertainties in orbit elements. Therefore, every filtering process is vulnerable to including objects that are not threats and excluding some that are threats, Type I and Type II errors. The approach in this paper guides selection of the best operating point for the filters suited to a user's tolerance for false alarms and unwarned threats. We demonstrate the approach using three archetypal filters with an initial three-day span, select filter parameters based on performance, and then test those parameters using eight historical snapshots of the space catalog. This work provides a mechanism for selecting filter parameters but the choices depend on the circumstances.

The evolution of phenotypes and genetic parameters under preferential mating

PubMed Central

Roff, Derek A; Fairbairn, Daphne J

2014-01-01

This article extends and adds more realism to Lande's analytical model for evolution under mate choice by using individual-based simulations in which females sample a finite number of males and the genetic architecture of the preference and preferred trait evolves. The simulations show that the equilibrium heritabilities of the preference and preferred trait and the genetic correlation between them (rG), depend critically on aspects of the mating system (the preference function, mode of mate choice, choosiness, and number of potential mates sampled), the presence or absence of natural selection on the preferred trait, and the initial genetic parameters. Under some parameter combinations, preferential mating increased the heritability of the preferred trait, providing a possible resolution for the lek paradox. The Kirkpatrick–Barton approximation for rG proved to be biased downward, but the realized genetic correlations were also low, generally <0.2. Such low values of rG indicate that coevolution of the preference and preferred trait is likely to be very slow and subject to significant stochastic variation. Lande's model accurately predicted the incidence of runaway selection in the simulations, except where preferences were relative and the preferred trait was subject to natural selection. In these cases, runaways were over- or underestimated, depending on the number of males sampled. We conclude that rapid coevolution of preferences and preferred traits is unlikely in natural populations, but that the parameter combinations most conducive to it are most likely to occur in lekking species. PMID:25077025

Substitution in recreation choice behavior

Treesearch

George L. Peterson; Daniel J. Stynes; Donald H. Rosenthal; John F. Dwyer

1985-01-01

This review discusses concepts and theories of substitution in recreation choice. It brings together the literature of recreation research, psychology, geography, economics, and transportation. Parallel and complementary developments need integration into an improved theory of substitution. Recreation decision behavior is characterized as a nested or sequential choice...

The ABCs of School Choice: The Comprehensive Guide to Every Private School Choice Program in America. 2013 Edition

ERIC Educational Resources Information Center

Friedman Foundation for Educational Choice, 2013

2013-01-01

"The ABCs of School Choice" is the most comprehensive guide to every private school choice program in America, showcasing the voucher, tax-credit scholarship, education savings accounts, and individual tax credit/deduction programs currently operating in 21 states and Washington, D.C. "The ABCs of School Choice" provides policymakers, advocates,…

Hierarchical competitions subserving multi-attribute choice

PubMed Central

Hunt, Laurence T; Dolan, Raymond J; Behrens, Timothy EJ

2015-01-01

Valuation is a key tenet of decision neuroscience, where it is generally assumed that different attributes of competing options are assimilated into unitary values. Such values are central to current neural models of choice. By contrast, psychological studies emphasize complex interactions between choice and valuation. Principles of neuronal selection also suggest competitive inhibition may occur in early valuation stages, before option selection. Here, we show behavior in multi-attribute choice is best explained by a model involving competition at multiple levels of representation. This hierarchical model also explains neural signals in human brain regions previously linked to valuation, including striatum, parietal and prefrontal cortex, where activity represents competition within-attribute, competition between attributes, and option selection. This multi-layered inhibition framework challenges the assumption that option values are computed before choice. Instead our results indicate a canonical competition mechanism throughout all stages of a processing hierarchy, not simply at a final choice stage. PMID:25306549

How to make moral choices.

PubMed

Chambers, David W

2011-01-01

Moral choice is committing to act for what one believes is right and good. It is less about what we know than about defining who we are. Three cases typical of those used in the principles or dilemmas approach to teaching ethics are presented. But they are analyzed using an alternative approach based on seven moral choice heuristics--approaches proven to increase the likelihood of locating the best course of action. The approaches suggested for analyzing moral choice situations include: (a) identify the outcomes of available alternative courses of action; (b) rule out strategies that involve deception, coercion, reneging on promises, collusion, and contempt for others; (c) be authentic (do not deceive yourself); (d) relate to others on a human basis; (e) downplay rational justifications; (f) match the solution to the problem, not the other way around; (g) execute on the best solution, do not hold out for the perfect one; and (h) take action to improve the choice after it has been made.

How do stereotypes influence choice?

PubMed

Chaxel, Anne-Sophie

2015-05-01

In the study reported here, I tracked one process through which stereotypes affect choice. The Implicit Association Test (IAT) and a measurement of predecisional information distortion were used to assess the influence of the association between male gender and career on the evaluation of information related to the job performance of stereotypical targets (male) and nonstereotypical targets (female). When the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a stereotypical target, decision makers supported the leader with more proleader distortion; when the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a nonstereotypical target, decision makers supported the trailer with less antitrailer distortion. A stronger association between male gender and career therefore resulted in an upward shift of the evaluation related to the stereotypical target (both as a trailer and a leader), which subsequently biased choice. © The Author(s) 2015.

AdChoices? Compliance with Online Behavioral Advertising Notice and Choice Requirements. Revised Version

DTIC Science & Technology

2011-10-07

further information and a means of opting out. Revised October 7, 2011. Keywords: Online behavioral advertising ; privacy; consumer choice; notice... consumers ’ activities online to target advertising .”1 The FTC has been examining ways to reduce the privacy concerns associated with OBA for over a decade...behavioral advertising practices that would foster transparency, knowledge and choice for consumers . As the FTC determines what to do next, it is

After the withdrawal of 'informed choice': the meanings and social effects of mothers' choice for HIV prevention in Senegal.

PubMed

Desclaux, Alice

2014-01-01

To prevent HIV transmission through breastfeeding, African health services in 1998 implemented the World Health Organization's approach of 'informed choice' when recommending infant feeding options to HIV-positive mothers. In 2010, 'informed choice' was withdrawn in favour of antiretroviral prophylaxis with breastfeeding. A 2010-11 ethnographic study conducted in Senegal among HIV-positive mothers revealed three broad responses to the withdrawal of choice and formula provision: 'resistance' from association members claiming the health system was responsible for providing formula to ensure efficient prevention; 'compliance' among mothers adopting 'protected breastfeeding' without complaints; and 'self-reliance' among women trying to obtain formula through other means without mentioning choice. These three responses shed light on the meanings attributed to choice and on the social impact of formula provision during the 'informed choice era.' The analysis shows that the top-down introduction of 'informed choice' as an ethical and management imperative was appropriated and re-signified locally, making space for new forms of sociality within medical and associative social spaces. These social forms could not easily be maintained after the withdrawal of formula provision; women who continue to exert choice do so silently. By focusing on the upheaval of social care arrangements after the introduction of prophylaxis by pharmaceuticals, this paper sheds light on the understudied local consequences of changes in public health policies and the social framing of 'choice' in low-income countries' health systems.

SPOTting Model Parameters Using a Ready-Made Python Package

NASA Astrophysics Data System (ADS)

Houska, Tobias; Kraft, Philipp; Chamorro-Chavez, Alejandro; Breuer, Lutz

2017-04-01

The choice for specific parameter estimation methods is often more dependent on its availability than its performance. We developed SPOTPY (Statistical Parameter Optimization Tool), an open source python package containing a comprehensive set of methods typically used to calibrate, analyze and optimize parameters for a wide range of ecological models. SPOTPY currently contains eight widely used algorithms, 11 objective functions, and can sample from eight parameter distributions. SPOTPY has a model-independent structure and can be run in parallel from the workstation to large computation clusters using the Message Passing Interface (MPI). We tested SPOTPY in five different case studies to parameterize the Rosenbrock, Griewank and Ackley functions, a one-dimensional physically based soil moisture routine, where we searched for parameters of the van Genuchten-Mualem function and a calibration of a biogeochemistry model with different objective functions. The case studies reveal that the implemented SPOTPY methods can be used for any model with just a minimal amount of code for maximal power of parameter optimization. They further show the benefit of having one package at hand that includes number of well performing parameter search methods, since not every case study can be solved sufficiently with every algorithm or every objective function.

SPOTting Model Parameters Using a Ready-Made Python Package.

PubMed

Houska, Tobias; Kraft, Philipp; Chamorro-Chavez, Alejandro; Breuer, Lutz

2015-01-01

The choice for specific parameter estimation methods is often more dependent on its availability than its performance. We developed SPOTPY (Statistical Parameter Optimization Tool), an open source python package containing a comprehensive set of methods typically used to calibrate, analyze and optimize parameters for a wide range of ecological models. SPOTPY currently contains eight widely used algorithms, 11 objective functions, and can sample from eight parameter distributions. SPOTPY has a model-independent structure and can be run in parallel from the workstation to large computation clusters using the Message Passing Interface (MPI). We tested SPOTPY in five different case studies to parameterize the Rosenbrock, Griewank and Ackley functions, a one-dimensional physically based soil moisture routine, where we searched for parameters of the van Genuchten-Mualem function and a calibration of a biogeochemistry model with different objective functions. The case studies reveal that the implemented SPOTPY methods can be used for any model with just a minimal amount of code for maximal power of parameter optimization. They further show the benefit of having one package at hand that includes number of well performing parameter search methods, since not every case study can be solved sufficiently with every algorithm or every objective function.

SPOTting Model Parameters Using a Ready-Made Python Package

PubMed Central

Houska, Tobias; Kraft, Philipp; Chamorro-Chavez, Alejandro; Breuer, Lutz

2015-01-01

The choice for specific parameter estimation methods is often more dependent on its availability than its performance. We developed SPOTPY (Statistical Parameter Optimization Tool), an open source python package containing a comprehensive set of methods typically used to calibrate, analyze and optimize parameters for a wide range of ecological models. SPOTPY currently contains eight widely used algorithms, 11 objective functions, and can sample from eight parameter distributions. SPOTPY has a model-independent structure and can be run in parallel from the workstation to large computation clusters using the Message Passing Interface (MPI). We tested SPOTPY in five different case studies to parameterize the Rosenbrock, Griewank and Ackley functions, a one-dimensional physically based soil moisture routine, where we searched for parameters of the van Genuchten-Mualem function and a calibration of a biogeochemistry model with different objective functions. The case studies reveal that the implemented SPOTPY methods can be used for any model with just a minimal amount of code for maximal power of parameter optimization. They further show the benefit of having one package at hand that includes number of well performing parameter search methods, since not every case study can be solved sufficiently with every algorithm or every objective function. PMID:26680783

Training impulsive choices for healthy and sustainable food.

PubMed

Veling, Harm; Chen, Zhang; Tombrock, Merel C; Verpaalen, Iris A M; Schmitz, Laura I; Dijksterhuis, Ap; Holland, Rob W

2017-06-01

Many people find it hard to change their dietary choices. Food choice often occurs impulsively, without deliberation, and it has been unclear whether impulsive food choice can be experimentally created. Across 3 exploratory and 2 confirmatory preregistered experiments we examined whether impulsive food choice can be trained. Participants were cued to make motor responses upon the presentation of, among others, healthy and sustainable food items. They subsequently selected these food items more often for actual consumption when they needed to make their choices impulsively as a result of time pressure. This effect disappeared when participants were asked to think about their choices, merely received more time to make their choices, or when choosing required attention to alternatives. Participants preferred high to low valued food items under time pressure and without time pressure, suggesting that the impulsive choices reflect valid preferences. These findings demonstrate that it is possible to train impulsive choices for food items while leaving deliberative choices for these items unaffected, and connect research on attention training to dual-process theories of decision making. The present research suggests that attention training may lead to behavioral change only when people behave impulsively. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Choice of modality with the use of high-performance membrane and evaluation for clinical effects.

PubMed

Masakane, Ikuto

2011-01-01

The golden target for dialysis therapy should be to guarantee longer survival and to give a higher quality of life without dialysis-related complications. In order to achieve this target, the choice of dialysis modality and membrane is essential but we have not yet established what the best choice for a dialysis modality and membrane are. Generally, we choose a dialysis modality for better solute removal and better biocompatibility. In this issue we would like to propose that the patients' preference for dialysis therapy is a useful parameter in prescribing the dialysis modality. In our recent experience, chronic dialysis patients have had preferences on a dialysis modality and membrane, those being PMMA, EVAL, AN-69 and pre-dilution online HDF. These modalities could relieve them of uncomfortable dialysis-related symptoms such as insomnia, itchiness, irritability, and so on. Other characteristics of these modalities are of a nutritional advantage, a broad removal pattern of uremic toxins including low-molecular-weight protein and protein-bound uremic toxins, and good biocompatibility free from chemical components of dialysis membrane. In conclusion, patients' symptoms could be a useful parameter to choose a dialysis modality and membrane. Copyright © 2011 S. Karger AG, Basel.

Own-Choice Marriage and Fertility in Turkey

PubMed Central

Weinreb, Alexander A.

2016-01-01

Goode’s foundational work on the fertility transition identified own-choice marriage as a factor driving fertility decline, part of a widening repertoire of choice pertaining to marriage and childbearing. Yet research supporting this connection in today’s transitional societies is scarce and somewhat contradictory, and it is unclear how other marital traditions, such as consanguineous marriage, shape this relationship. This study evaluates Goode’s theorized connection using pooled Demographic and Health Survey data from Turkey, comparing children ever born, use of contraception, and parity progression across four types of marriage: own-choice and arranged marriage; and marriage to a cousin versus an unrelated spouse. Results are largely consistent with the idea that a move towards own-choice marriage reflects a widening repertoire of choice that also leads to fertility decline. However, they also show that hybrid models like own-choice marriage to a cousin tempers these effects. PMID:28316343

Own-Choice Marriage and Fertility in Turkey.

PubMed

Manglos-Weber, Nicolette D; Weinreb, Alexander A

2017-04-01

Goode's foundational work on the fertility transition identified own-choice marriage as a factor driving fertility decline, part of a widening repertoire of choice pertaining to marriage and childbearing. Yet research supporting this connection in today's transitional societies is scarce and somewhat contradictory, and it is unclear how other marital traditions, such as consanguineous marriage, shape this relationship. This study evaluates Goode's theorized connection using pooled Demographic and Health Survey data from Turkey, comparing children ever born, use of contraception, and parity progression across four types of marriage: own-choice and arranged marriage; and marriage to a cousin versus an unrelated spouse. Results are largely consistent with the idea that a move towards own-choice marriage reflects a widening repertoire of choice that also leads to fertility decline. However, they also show that hybrid models like own-choice marriage to a cousin tempers these effects.

School Choice: Examining the Evidence.

ERIC Educational Resources Information Center

Rasell, Edith, Ed.; Rothstein, Richard, Ed.

This book presents a summary of school-choice issues, and is organized around a 1992 seminar entitled "Choice: What Role in American Education?" Each part presents a set of conference papers, followed by discussants' remarks and excerpts from audience discussion. The introduction summarizes the papers' positions and conclusions. Participants…

Correlation Relation for the Membrane Transport ParametersL(p), σ, and ω.

PubMed

Kargol, A; Kargol, M; Przestalski, S

1997-12-01

We derive a formula for the correlation of the three practical transportparameters L(p), σ, and ω appearing in Kedem-Katchalskyequations. It has a form ω = KL(p)/v(s)(1-σ), where K = 0.0306 is a universal constant independent ofthe choice of a membrane and a solute. It can be used to calculate the valueof any of these parameters, provided the other two and the molar volume[Formula: see text] of the solute are known. The formula couldbe very useful, in particular when measurements of the parameters aredifficult or even impossible.

Measuring the loss of consumer choice in mandatory health programmes using discrete choice experiments.

PubMed

Parkinson, Bonny; Goodall, Stephen; Norman, Richard

2013-04-01

Economic evaluation of mandatory health programmes generally do not consider the utility impact of a loss of consumer choice upon implementation, despite evidence suggesting that consumers do value having the ability to choose. The primary aim of this study was to explore whether the utility impact of a loss of consumer choice from implementing mandatory health programmes can be measured using discrete choice experiments (DCEs). Three case studies were used to test the methodology: fortification of bread-making flour with folate, mandatory influenza vaccination of children, and the banning of trans-fats. Attributes and levels were developed from a review of the literature. An orthogonal, fractional factorial design was used to select the profiles presented to respondents to allow estimation of main effects. Overall, each DCE consisted of 64 profiles which were allocated to four versions of 16 profiles. Each choice task compared two profiles, one being voluntary and the other being mandatory, plus a 'no policy' option, thus each respondent was presented with eight choice tasks. For each choice task, respondents were asked which health policy they most preferred and least preferred. Data was analysed using a mixed logit model with correlated coefficients (200 Halton draws). The compensating variation required for introducing a programme on a mandatory basis (versus achieving the same health impacts with a voluntary programme) that holds utility constant was estimated. Responses were provided by 535 participants (a response rate of 83 %). For the influenza vaccination and folate fortification programmes, the results suggested that some level of compensation may be required for introducing the programme on a mandatory basis. Introducing a mandatory influenza vaccination programme required the highest compensation (Australian dollars [A$] 112.75, 95 % CI -60.89 to 286.39) compared with folate fortification (A$18.05, 95 % CI -3.71 to 39.80). No compensation was

[New trends of customizing intraocular lens choice].

PubMed

He, Shou-zhi

2006-05-01

Definition and basic principle of customizing intraocular lens choice are described. The importance of the choicing intraocular lens for individual patient is illustrated. The review emphasizes that it is surgeon's responsibility to choice the appropriate intraocular lens for the best postoperative outcome and patient's satisfaction.

Towards cheaper control centers

NASA Technical Reports Server (NTRS)

Baize, Lionel

1994-01-01

Today, any approach to the design of new space systems must take into consideration an important constraint, namely costs. This approach is our guideline for new missions and also applies to the ground segment, and particularly to the control center. CNES has carried out a study on a recent control center for application satellites in order to take advantage of the experience gained. This analysis, the purpose of which is to determine, a posteriori, the costs of architecture needs and choices, takes hardware and software costs into account and makes a number of recommendations.

Resolving the paradox of suboptimal choice.

PubMed

Zentall, Thomas R

2016-01-01

When humans engage in commercial (totally probabilistic) gambling they are making suboptimal choices because the return is generally less than the investment. This review (a) examines the literature on pigeon suboptimal choice, (b) describes the conditions under which it occurs, (c) identifies the mechanisms that appear to be responsible for the effect, and (d) suggests that similar processes may be able to account for analogous suboptimal choice when humans engage in commercial gambling. Pigeons show suboptimal choice when they choose between 1 alternative that 20% of the time provides them with a signal that they will always get fed or 80% of the time with a signal that they will not get fed (overall 20% reinforcement) and a second alternative that 100% of the time provides them with a signal that they will get fed 50% of the time (overall 50% reinforcement). The pigeons' strong preference for the suboptimal choice was investigated in a series of experiments that found the preference for the suboptimal alternative was determined by the value of the signal that predicted reinforcement, rather its frequency and that the frequency of the signal that predicted nonreinforcement had little effect on the suboptimal choice. Paradoxically, this account makes the prediction that pigeons will be indifferent between an alternative that 50% of the time provides a fully predictive stimulus for reinforcement and an alternative that 100% of the time provides a fully predictive stimulus for reinforcement. The similarities and differences of this suboptimal choice task to human gambling are discussed. (c) 2016 APA, all rights reserved).

The Globalisation of School Choice?

ERIC Educational Resources Information Center

Forsey, Martin, Ed.; Davies, Scott, Ed.; Walford, Geoffrey, Ed.

2008-01-01

"Which school should I choose for my child?" For many parents, this question is one of the most important of their lives. "School choice" is a slogan being voiced around the globe, conjuring images of a marketplace with an abundance of educational options. Those promoting educational choice also promise equality, social…

Combining food type(s) and food quantity choice in a new food choice paradigm based on vice-virtue bundles.

PubMed

Haws, Kelly L; Liu, Peggy J

2016-08-01

Given the prevalence and rising rates of obesity in many countries, including the United States, much food decision-making research ultimately aims at understanding how consumers can make healthier choices. The two predominant choice paradigms used in food decision-making research ask consumers to choose (a) between a "vice" (or unhealthy food) and a "virtue" (or healthy food) or (b) among varying portion sizes of "vice." We propose a new food choice paradigm that encourages consumers to jointly consider both food type(s) choice and food portion size at each decision point. The purpose of this paradigm is two-fold. First, it aims to allow examination of more comprehensive eating behavior (e.g., to examine the overall composition of a plate of food rather than choice of a single food). Second, it aims to shift consumers towards including large proportions of virtues and smaller proportions of vice in their overall consumption portfolios. For this paradigm, we draw upon a recently introduced food product innovation called "vice-virtue bundles" (Liu et al., 2015) that illustrates the basis of this new food choice paradigm, in which food type(s) and portion decisions are made simultaneously. Accordingly, we first discuss relevant findings on vice-virtue bundles as well as the differences between simultaneous and sequential choice of multiple products. Second, we examine the benefits for managing and controlling one's consumption that are provided by vice-virtue bundles and this joint food choice paradigm more generally. Third and finally, we point out opportunities for future research by discussing (a) multiple factors that influence food choices, (b) decision processes affected by food choice paradigms, and (c) issues of generalizability related to the presence of vice-virtue bundles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Education by the Numbers: The Fiscal Effect of School Choice Programs, 1990-2006. School Choice Issues in Depth

ERIC Educational Resources Information Center

Aud, Susan L.

2007-01-01

School choice programs, which allow students to attend the public or private school of their choice using public funds, have taken root in the U.S. and are growing rapidly both in number and size. Their fiscal impact has become an important political issue. Proponents say school choice saves money because private schooling is more efficient,…

Choosing health, constrained choices.

PubMed

Chee Khoon Chan

2009-12-01

In parallel with the neo-liberal retrenchment of the welfarist state, an increasing emphasis on the responsibility of individuals in managing their own affairs and their well-being has been evident. In the health arena for instance, this was a major theme permeating the UK government's White Paper Choosing Health: Making Healthy Choices Easier (2004), which appealed to an ethos of autonomy and self-actualization through activity and consumption which merited esteem. As a counterpoint to this growing trend of informed responsibilization, constrained choices (constrained agency) provides a useful framework for a judicious balance and sense of proportion between an individual behavioural focus and a focus on societal, systemic, and structural determinants of health and well-being. Constrained choices is also a conceptual bridge between responsibilization and population health which could be further developed within an integrative biosocial perspective one might refer to as the social ecology of health and disease.

Nucleus accumbens core lesions induce sub-optimal choice and reduce sensitivity to magnitude and delay in impulsive choice tasks

PubMed Central

Steele, Catherine C.; Peterson, Jennifer R.; Marshall, Andrew T.; Stuebing, Sarah L.; Kirkpatrick, Kimberly

2017-01-01

The nucleus accumbens core (NAc) has long been recognized as an important contributor to the computation of reward value that is critical for impulsive choice behavior. Impulsive choice refers to choosing a smaller-sooner (SS) over a larger-later (LL) reward when the LL is more optimal in terms of the rate of reward delivery. Two experiments examined the role of the NAc in impulsive choice and its component processes of delay and magnitude processing. Experiment 1 delivered an impulsive choice task with manipulations of LL reward magnitude, followed by a reward magnitude discrimination task. Experiment 2 tested impulsive choice under manipulations of LL delay, followed by temporal bisection and progressive interval tasks. NAc lesions, in comparison to sham control lesions, produced suboptimal preferences that resulted in lower reward earning rates, and led to reduced sensitivity to magnitude and delay within the impulsive choice task. The secondary tasks revealed intact reward magnitude and delay discrimination abilities, but the lesion rats persisted in responding more as the progressive interval increased during the session. The results suggest that the NAc is most critical for demonstrating good sensitivity to magnitude and delay, and adjusting behavior accordingly. Ultimately, the NAc lesions induced suboptimal choice behavior rather than simply promoting impulsive choice, suggesting that an intact NAc is necessary for optimal decision making. PMID:29146281

Measurement of ethical food choice motives.

PubMed

Lindeman, M; Väänänen, M

2000-02-01

The two studies describe the development of three complementary scales to the Food Choice Questionnaire developed by Steptoe, Pollard & Wardle (1995). The new items address various ethical food choice motives and were derived from previous studies on vegetarianism and ethical food choice. The items were factor analysed in Study 1 (N=281) and the factor solution was confirmed in Study 2 (N=125), in which simple validity criteria were also included. Furthermore, test-retest reliability was assessed with a separate sample of subjects (N=36). The results indicated that the three new scales, Ecological Welfare (including subscales for Animal Welfare and Environment Protection), Political Values and Religion, are reliable and valid instruments for a brief screening of ethical food choice reasons. Copyright 2000 Academic Press.

Centering in on Professional Choices.

ERIC Educational Resources Information Center

Harris, Muriel

2001-01-01

Examines the author's involvement with writing centers as an example of how educators can look at the choices made within their areas of expertise to see why the choices attract them. Notes that in her case, the flexible, collaborative, individualized, non-evaluative, experimental, non-hierarchical, student-centered nature of writing centers is an…

Sex Education: Challenges and Choices

ERIC Educational Resources Information Center

MacKenzie, Alison; Hedge, Nicki; Enslin, Penny

2017-01-01

Noting public concern about sexual exploitation, abuse and sexualisation, we argue that sex education in the UK needs revision. Choice is a feature of current sex education policy and, acknowledging that choice can be problematic, we defend its place in an approach to sex education premised on informed deliberation, relational autonomy, a…

School Choice with Chinese Characteristics

ERIC Educational Resources Information Center

Wu, Xiaoxin

2012-01-01

This paper explores the major characteristics of school choice in the Chinese context. It highlights the involvement of cultural and economic capital, such as choice fees, donations, prize-winning certificates and awards in gaining school admission, as well as the use of social capital in the form of "guanxi". The requirement for these…

Back to Basics--The Influence of DNA Extraction and Primer Choice on Phylogenetic Analysis of Activated Sludge Communities.

PubMed

Albertsen, Mads; Karst, Søren M; Ziegler, Anja S; Kirkegaard, Rasmus H; Nielsen, Per H

2015-01-01

DNA extraction and primer choice have a large effect on the observed community structure in all microbial amplicon sequencing analyses. Although the biases are well known, no comprehensive analysis has been conducted in activated sludge communities. In this study we systematically explored the impact of a number of parameters on the observed microbial community: bead beating intensity, primer choice, extracellular DNA removal, and various PCR settings. In total, 176 samples were subjected to 16S rRNA amplicon sequencing, and selected samples were investigated through metagenomics and metatranscriptomics. Quantitative fluorescence in situ hybridization was used as a DNA extraction-independent method for qualitative comparison. In general, an effect on the observed community was found on all parameters tested, although bead beating and primer choice had the largest effect. The effect of bead beating intensity correlated with cell-wall strength as seen by a large increase in DNA from Gram-positive bacteria (up to 400%). However, significant differences were present at lower phylogenetic levels within the same phylum, suggesting that additional factors are at play. The best primer set based on in silico analysis was found to underestimate a number of important bacterial groups. For 16S rRNA gene analysis in activated sludge we recommend using the FastDNA SPIN Kit for Soil with four times the normal bead beating and V1-3 primers.

Partner choice creates fairness in humans.

PubMed

Debove, Stéphane; André, Jean-Baptiste; Baumard, Nicolas

2015-06-07

Many studies demonstrate that partner choice has played an important role in the evolution of human cooperation, but little work has tested its impact on the evolution of human fairness. In experiments involving divisions of money, people become either over-generous or over-selfish when they are in competition to be chosen as cooperative partners. Hence, it is difficult to see how partner choice could result in the evolution of fair, equal divisions. Here, we show that this puzzle can be solved if we consider the outside options on which partner choice operates. We conduct a behavioural experiment, run agent-based simulations and analyse a game-theoretic model to understand how outside options affect partner choice and fairness. All support the conclusion that partner choice leads to fairness only when individuals have equal outside options. We discuss how this condition has been met in our evolutionary history, and the implications of these findings for our understanding of other aspects of fairness less specific than preferences for equal divisions of resources. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Choice in School: Its Importance and Scope

ERIC Educational Resources Information Center

Yagnamurthy, Sreekanth

2013-01-01

The author reviews various factors defining school choice, and school curricula. A key assumption behind the rhetoric logic of school choice is the notion that parents actually choose from schools of varying quality. If parents choose from high-quality schools, choice policy will enhance educational opportunities. If, however, the considered…

Preference Reversal in Multiattribute Choice

ERIC Educational Resources Information Center

Tsetsos, Konstantinos; Usher, Marius; Chater, Nick

2010-01-01

A central puzzle for theories of choice is that people's preferences between options can be reversed by the presence of decoy options (that are not chosen) or by the presence of other irrelevant options added to the choice set. Three types of reversal effect reported in the decision-making literature, the attraction, compromise, and similarity…

College Choice in the Philippines

ERIC Educational Resources Information Center

Tan, Christine Joy

2009-01-01

This descriptive and correlational study examined the applicability of major U.S. college choice factors to Philippine high school seniors. A sample of 226 students from a private school in Manila completed the College Choice Survey for High School Seniors. Cronbach's alpha for the survey composite index was 0.933. The purposes of this…

Pharmacokinetics, phenotype and product choice in haemophilia B: how to strike a balance?

PubMed

Berntorp, E; Dolan, G; Hermans, C; Laffan, M; Santagostino, E; Tiede, A

2014-11-01

At the 7th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD) held in Brussels, Belgium, in February 2014, Pfizer sponsored a satellite symposium entitled: "Pharmacokinetics, phenotype and product choice in haemophilia B: How to strike a balance?" Co-chaired by Cedric Hermans (Cliniques Universitaires Saint Luc, Brussels, Belgium) and Mike Laffan (Imperial College, London, UK), the symposium provided an opportunity to debate whether pharmacokinetic (PK) parameters are good surrogates for clinical efficacy for haemophilia B in clinical practice, consider the perceptions and evidence of disease severity, and examine how these considerations can inform approaches to balancing the potential risks and benefits of the currently available treatment options for haemophilia B. PK parameters are routinely measured in clinical practice and are a requirement of regulatory bodies to demonstrate the clinical efficacy of products; however, the relationship between measured PK parameters and clinical efficacy is yet to be determined, an issue that was debated by Gerry Dolan (University Hospital, Queen's Medical Centre, Nottingham, UK) and Erik Berntorp (Lund University, Malmö Centre for Thrombosis and Haemostasis, Malmö, Sweden). Elena Santagostino (Universita degli Studi di Milano, Milano, Italy) reviewed how differing perceptions on the severity of haemophilia B compared with haemophilia A may have an impact on clinical decision-making. Finally, Andreas Tiede (Hannover Medical School, Hannover, Germany), examined the considerations for balancing the potential risks and benefits of the currently available treatment options for haemophilia B. Although the pathophysiology of haemophilia B has been widely studied and is largely understood, continued investigation and discussion around the optimal management course and appropriate therapeutic choice is warranted. © 2014 John Wiley & Sons Ltd.

Rethinking School Choice: Limits of the Market Metaphor.

ERIC Educational Resources Information Center

Henig, Jeffrey R.

The appropriateness of the market metaphor as a guide to education policy with respect to school choice is discussed, and the theory and practice of school choice and the history of the choice movement are traced. School choice has at times become a vehicle for racial and economic segregation and a way to deny, rather than promote, access to…

Functional MRI of Challenging Food Choices: Forced Choice between Equally Liked High- and Low-Calorie Foods in the Absence of Hunger.

PubMed

Charbonnier, Lisette; van der Laan, Laura N; Viergever, Max A; Smeets, Paul A M

2015-01-01

We are continuously exposed to food and during the day we make many food choices. These choices play an important role in the regulation of food intake and thereby in weight management. Therefore, it is important to obtain more insight into the mechanisms that underlie these choices. While several food choice functional MRI (fMRI) studies have been conducted, the effect of energy content on neural responses during food choice has, to our knowledge, not been investigated before. Our objective was to examine brain responses during food choices between equally liked high- and low-calorie foods in the absence of hunger. During a 10-min fMRI scan 19 normal weight volunteers performed a forced-choice task. Food pairs were matched on individual liking but differed in perceived and actual caloric content (high-low). Food choice compared with non-food choice elicited stronger unilateral activation in the left insula, superior temporal sulcus, posterior cingulate gyrus and (pre)cuneus. This suggests that the food stimuli were more salient despite subject's low motivation to eat. The right superior temporal sulcus (STS) was the only region that exhibited greater activation for high versus low calorie food choices between foods matched on liking. Together with previous studies, this suggests that STS activation during food evaluation and choice may reflect the food's biological relevance independent of food preference. This novel finding warrants further research into the effects of hunger state and weight status on STS, which may provide a marker of biological relevance.

Functional MRI of Challenging Food Choices: Forced Choice between Equally Liked High- and Low-Calorie Foods in the Absence of Hunger

PubMed Central

Charbonnier, Lisette; van der Laan, Laura N.; Viergever, Max A.; Smeets, Paul A. M.

2015-01-01

We are continuously exposed to food and during the day we make many food choices. These choices play an important role in the regulation of food intake and thereby in weight management. Therefore, it is important to obtain more insight into the mechanisms that underlie these choices. While several food choice functional MRI (fMRI) studies have been conducted, the effect of energy content on neural responses during food choice has, to our knowledge, not been investigated before. Our objective was to examine brain responses during food choices between equally liked high- and low-calorie foods in the absence of hunger. During a 10-min fMRI scan 19 normal weight volunteers performed a forced-choice task. Food pairs were matched on individual liking but differed in perceived and actual caloric content (high-low). Food choice compared with non-food choice elicited stronger unilateral activation in the left insula, superior temporal sulcus, posterior cingulate gyrus and (pre)cuneus. This suggests that the food stimuli were more salient despite subject’s low motivation to eat. The right superior temporal sulcus (STS) was the only region that exhibited greater activation for high versus low calorie food choices between foods matched on liking. Together with previous studies, this suggests that STS activation during food evaluation and choice may reflect the food’s biological relevance independent of food preference. This novel finding warrants further research into the effects of hunger state and weight status on STS, which may provide a marker of biological relevance. PMID:26167916

Factors dominating choice of surgical specialty.

PubMed

Reed, Carolyn E; Vaporciyan, Ara A; Erikson, Clease; Dill, Michael J; Carpenter, Andrea J; Guleserian, Kristine J; Merrill, Walter H

2010-03-01

There has been much focus on factors influencing medical students' career choice, prompted by such concerns as a sufficient future surgical workforce, declining applicant pool, changing gender composition, and a cultural shift in values and priorities. Once in a surgical residency, there are little data on factors influencing general surgery (GS) residents' final specialty choice. A survey instrument was developed and content validated in conjunction with the Association of American Medical Colleges Center for Workforce Studies. The final instrument was distributed electronically between March 24 and May 2, 2008, through 251 GS program directors to all ACGME-accredited GS residents (n = 7,508). Response rate was 29% (2,153 residents; 89% programs). Half of GS residents remained undecided about specialty choice through the 2(nd) year, declining to 2% by year 5. Of the two-thirds who decided on a specialty, 16.5% chose to remain in GS, 14.6% chose plastics, 9.3% cardiothoracic, and 8.5% vascular. The specialty choice factors most likely to be very important were type of procedures and techniques, exposure to positive role model, and ability to balance work and personal life. Relative importance of factors in specialty choice varied by gender and chosen specialty. Mentors play a key role in specialty choice (66% decided had mentors versus 47% undecided). Work schedule was the most frequently selected shortcoming in every specialty except plastics. Cardiothoracic surgery followed by GS had the highest shortcomings. The majority of GS residents plan to subspecialize. Three factors dominate specialty choice. Faculty need to understand their impact potential to modify or change perceptions of their specialty. Copyright 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

CHOICE (Considering Honest Options in Career Exploration).

ERIC Educational Resources Information Center

Langford, Carolyn

The Considering Honest Options in Career Exploration (CHOICE) program is a career decision-making plan designed to assist counselors and teachers in helping high school juniors and seniors develop specific written career plans that they can implement after high school. This guide includes an overview of CHOICE and three CHOICE learning modules.…

EDUCATIONAL AND OCCUPATIONAL CHOICES OF FARM YOUTH.

ERIC Educational Resources Information Center

HALLER, ARCHIBALD O.

EDUCATIONAL AND OCCUPATIONAL ALTERNATIVES OPEN TO FARM BOYS AND GIRLS, THE FACTORS INFLUENCING THEIR JOB CHOICE, THE EFFECTS OF THEIR CHOICES ON THEIR JOB PERFORMANCE, AND WAYS OF IMPROVING THEIR CHOICES ARE DISCUSSED. INFORMATION IS BASED ON PERTINENT LITERATURE IN THE FIELD. THE ORGANIZATION OF THE OCCUPATIONAL STRUCTURE IS SUCH THAT THE MORE…

Discrepancy between Snack Choice Intentions and Behavior

ERIC Educational Resources Information Center

Weijzen, Pascalle L. G.; de Graaf, Cees; Dijksterhuis, Garmt B.

2008-01-01

Objective: To investigate dietary constructs that affect the discrepancy between intentioned and actual snack choice. Design: Participants indicated their intentioned snack choice from a set of 4 snacks (2 healthful, 2 unhealthful). One week later, they actually chose a snack from the same set. Within 1 week after the actual choice, they completed…

Your Choice Beyond a Degree.

ERIC Educational Resources Information Center

Crowther, Roger, Ed.

A major aim of this book (part of the Careers Research and Advisory Centre Choice Series) is to assist college bound students in England who are about to choose their degree course of study, to understand the implications, especially those reflecting recent employment trends for graduates, of their choice in career terms. Section I contains two…

Religious Education and Religious Choice

ERIC Educational Resources Information Center

Hand, Michael

2015-01-01

According to the "religious choice case" for compulsory religious education, pupils have a right to be made aware of the religious and irreligious paths open to them and equipped with the wherewithal to choose between them. A familiar objection to this argument is that the idea of religious choice reduces religion to a matter of taste. I…

Choice from non-choice: predicting consumer preferences from blood oxygenation level-dependent signals obtained during passive viewing.

PubMed

Levy, Ifat; Lazzaro, Stephanie C; Rutledge, Robb B; Glimcher, Paul W

2011-01-05

Decision-making is often viewed as a two-stage process, where subjective values are first assigned to each option and then the option of the highest value is selected. Converging evidence suggests that these subjective values are represented in the striatum and medial prefrontal cortex (MPFC). A separate line of evidence suggests that activation in the same areas represents the values of rewards even when choice is not required, as in classical conditioning tasks. However, it is unclear whether the same neural mechanism is engaged in both cases. To address this question we measured brain activation with functional magnetic resonance imaging while human subjects passively viewed individual consumer goods. We then sampled activation from predefined regions of interest and used it to predict subsequent choices between the same items made outside of the scanner. Our results show that activation in the striatum and MPFC in the absence of choice predicts subsequent choices, suggesting that these brain areas represent value in a similar manner whether or not choice is required.

The memorial consequences of multiple-choice testing.

PubMed

Marsh, Elizabeth J; Roediger, Henry L; Bjork, Robert A; Bjork, Elizabeth L

2007-04-01

The present article addresses whether multiple-choice tests may change knowledge even as they attempt to measure it. Overall, taking a multiple-choice test boosts performance on later tests, as compared with non-tested control conditions. This benefit is not limited to simple definitional questions, but holds true for SAT II questions and for items designed to tap concepts at a higher level in Bloom's (1956) taxonomy of educational objectives. Students, however, can also learn false facts from multiple-choice tests; testing leads to persistence of some multiple-choice lures on later general knowledge tests. Such persistence appears due to faulty reasoning rather than to an increase in the familiarity of lures. Even though students may learn false facts from multiple-choice tests, the positive effects of testing outweigh this cost.

14 CFR § 1214.117 - Launch and orbit parameters for a standard launch.

Code of Federal Regulations, 2014 CFR

2014-01-01

... flights: (1) Launch from Kennedy Space Center (KSC) into the customer's choice of two standard mission... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Launch and orbit parameters for a standard launch. § 1214.117 Section § 1214.117 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE...

The Stay/Switch Model of Concurrent Choice

ERIC Educational Resources Information Center

MacDonall, James S.

2009-01-01

This experiment compared descriptions of concurrent choice by the stay/switch model, which says choice is a function of the reinforcers obtained for staying at and for switching from each alternative, and the generalized matching law, which says choice is a function of the total reinforcers obtained at each alternative. For the stay/switch model…

Comparison of parameters of modern cooled and uncooled thermal cameras

NASA Astrophysics Data System (ADS)

Bareła, Jarosław; Kastek, Mariusz; Firmanty, Krzysztof; Krupiński, Michał

2017-10-01

During the design of a system employing thermal cameras one always faces a problem of choosing the camera types best suited for the task. In many cases such a choice is far from optimal one, and there are several reasons for that. System designers often favor tried and tested solution they are used to. They do not follow the latest developments in the field of infrared technology and sometimes their choices are based on prejudice and not on facts. The paper presents the results of measurements of basic parameters of MWIR and LWIR thermal cameras, carried out in a specialized testing laboratory. The measured parameters are decisive in terms of image quality generated by thermal cameras. All measurements were conducted according to current procedures and standards. However the camera settings were not optimized for a specific test conditions or parameter measurements. Instead the real settings used in normal camera operations were applied to obtain realistic camera performance figures. For example there were significant differences between measured values of noise parameters and catalogue data provided by manufacturers, due to the application of edge detection filters to increase detection and recognition ranges. The purpose of this paper is to provide help in choosing the optimal thermal camera for particular application, answering the question whether to opt for cheaper microbolometer device or apply slightly better (in terms of specifications) yet more expensive cooled unit. Measurements and analysis were performed by qualified personnel with several dozen years of experience in both designing and testing of thermal camera systems with both cooled and uncooled focal plane arrays. Cameras of similar array sizes and optics were compared, and for each tested group the best performing devices were selected.

Propranolol reduces reference-dependence in intertemporal choice

PubMed Central

Lempert, Karolina M.; Lackovic, Sandra F.; Tobe, Russell H.; Glimcher, Paul W.

2017-01-01

Abstract In intertemporal choices between immediate and delayed rewards, people tend to prefer immediate rewards, often even when the delayed reward is larger. This is known as temporal discounting. It has been proposed that this tendency emerges because immediate rewards are more emotionally arousing than delayed rewards. However, in our previous research, we found no evidence for this but instead found that arousal responses (indexed with pupil dilation) in intertemporal choice are context-dependent. Specifically, arousal tracks the subjective value of the more variable reward option in the paradigm, whether it is immediate or delayed. Nevertheless, people tend to choose the less variable option in the choice task. In other words, their choices are reference-dependent and depend on variance in their recent history of offers. This suggests that there may be a causal relationship between reference-dependent choice and arousal, which we investigate here by reducing arousal pharmacologically using propranolol. Here, we show that propranolol reduces reference-dependence, leading to choices that are less influenced by recent history and more internally consistent. PMID:28992268

The public's opinions of physicians: do perceived choice and exercised choice matter?

PubMed

Tai-Seale, Ming; Pescosolido, Bernice

2003-09-01

To assess whether the public's opinions of physicians are affected by one's perceived ability to choose providers and by past experience with switching providers or health plans. Cross-sectional survey of the American general public in 1998. Multivariate quantitative analyses of opinions according to respondents' perceived ability to choose providers, history of exercising choice of providers or plans, and health status. Exploratory factor analyses resulted in 4 scales of opinions: trusting personal physician, positive opinions of physicians as a group, negative opinions of physicians as a group, and concerns about the influence of managed care on personal physicians' practice patterns. Although 75% (879/1172) of the sample perceived that they could use any physician they wanted, only 20% had ever switched health providers or plans owing to dissatisfaction. Perceived lack of choice is associated with lower levels of trust in personal physicians and with higher levels of concern about the influence of managed care on personal physicians. Individuals who have not switched in the past are more positive about physicians as a group and are less concerned about the influence of managed care. Health status affected opinions significantly. Educational attainment is negatively associated with opinions. The public's opinions of physicians are significantly associated with one's perceived ability to choose any provider, past experience with switching health providers or plans, health status, and education. Ensuring consumer choice of providers and targeting those who have switched in the past and the sick could potentially improve the public's opinions. Meaningful provider quality information is necessary to ensure choices that can enhance consumer welfare.

Optimized bioregenerative space diet selection with crew choice

NASA Technical Reports Server (NTRS)

Vicens, Carrie; Wang, Carolyn; Olabi, Ammar; Jackson, Peter; Hunter, Jean

2003-01-01

Previous studies on optimization of crew diets have not accounted for choice. A diet selection model with crew choice was developed. Scenario analyses were conducted to assess the feasibility and cost of certain crew preferences, such as preferences for numerous-desserts, high-salt, and high-acceptability foods. For comparison purposes, a no-choice and a random-choice scenario were considered. The model was found to be feasible in terms of food variety and overall costs. The numerous-desserts, high-acceptability, and random-choice scenarios all resulted in feasible solutions costing between 13.2 and 17.3 kg ESM/person-day. Only the high-sodium scenario yielded an infeasible solution. This occurred when the foods highest in salt content were selected for the crew-choice portion of the diet. This infeasibility can be avoided by limiting the total sodium content in the crew-choice portion of the diet. Cost savings were found by reducing food variety in scenarios where the preference bias strongly affected nutritional content.

14 CFR 1260.59 - Choice of law.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Choice of law. 1260.59 Section 1260.59... Special Conditions § 1260.59 Choice of law. Choice of Law October 2000 The rights and obligations of the parties to the grant (or cooperative agreement) shall be ascertainable by recourse to the laws of the...

14 CFR 1260.59 - Choice of law.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Choice of law. 1260.59 Section 1260.59... Special Conditions § 1260.59 Choice of law. Choice of Law October 2000 The rights and obligations of the parties to the grant (or cooperative agreement) shall be ascertainable by recourse to the laws of the...

Economic rationality in choosing between short-term bad-health choices and longer-term good-health choices.

PubMed

Campbell, David

2013-11-08

Non-contagious, chronic disease has been identified as a global health risk. Poor lifestyle choices, such as smoking, alcohol, drug and solvent abuse, physical inactivity, and unhealthy diet have been identified as important factors affecting the increasing incidence of chronic disease. The following focuses on the circumstance affecting the lifestyle or behavioral choices of Aboriginal and Torres Strait Islander peoples in remote-/very remote Australia. Poor behavioral choices are the result of endogenous characteristics that are influenced by a range of stressful exogenous variables making up the psychosocial determinants including social disenfranchisement, cultural loss, insurmountable tasks, the loss of volitional control and resource constraints. It is shown that poor behavioral choices can be economically rational; especially under highly stressful conditions. Stressful circumstances erode individual capacity to commit to long-term positive health alternatives such as self-investment in education. Policies directed at removing the impediments and providing incentives to behaviors involving better health choices can lead to reductions in smoking and alcohol consumption and improved health outcomes. Multijurisdictional culturally acceptable policies directed at distal variables relating to the psychosocial determinants of health and personal mastery and control can be cost effective. While the content of this paper is focused on the conditions of colonized peoples, it has broader relevance.

The Supply Side of Choice

ERIC Educational Resources Information Center

Hill, Paul T.

2005-01-01

New school creation is key to success of choice. For the last two decades, the struggle over school choice has focused on freeing up parents to choose. It continues to this day, with growing success in the forms of public and private voucher programs, charter school laws in 40 states and the District of Columbia, and state and federal laws that…

34 CFR 361.52 - Informed choice.

Code of Federal Regulations, 2010 CFR

2010-07-01

... individual (including students with disabilities who are making the transition from programs under the... disabilities who require assistance in exercising informed choice throughout the vocational rehabilitation... eligible individuals meaningful choices among the methods used to procure vocational rehabilitation...

Patient choice in opt-in, active choice, and opt-out HIV screening: randomized clinical trial.

PubMed

Montoy, Juan Carlos C; Dow, William H; Kaplan, Beth C

2016-01-19

What is the effect of default test offers--opt-in, opt-out, and active choice--on the likelihood of acceptance of an HIV test among patients receiving care in an emergency department? This was a randomized clinical trial conducted in the emergency department of an urban teaching hospital and regional trauma center. Patients aged 13-64 years were randomized to opt-in, opt-out, and active choice HIV test offers. The primary outcome was HIV test acceptance percentage. The Denver Risk Score was used to categorize patients as being at low, intermediate, or high risk of HIV infection. 38.0% (611/1607) of patients in the opt-in testing group accepted an HIV test, compared with 51.3% (815/1628) in the active choice arm (difference 13.3%, 95% confidence interval 9.8% to 16.7%) and 65.9% (1031/1565) in the opt-out arm (difference 27.9%, 24.4% to 31.3%). Compared with active choice testing, opt-out testing led to a 14.6 (11.1 to 18.1) percentage point increase in test acceptance. Patients identified as being at intermediate and high risk were more likely to accept testing than were those at low risk in all arms (difference 6.4% (3.4% to 9.3%) for intermediate and 8.3% (3.3% to 13.4%) for high risk). The opt-out effect was significantly smaller among those reporting high risk behaviors, but the active choice effect did not significantly vary by level of reported risk behavior. Patients consented to inclusion in the study after being offered an HIV test, and inclusion varied slightly by treatment assignment. The study took place at a single county hospital in a city that is somewhat unique with respect to HIV testing; although the test acceptance percentages themselves might vary, a different pattern for opt-in versus active choice versus opt-out test schemes would not be expected. Active choice is a distinct test regimen, with test acceptance patterns that may best approximate patients' true preferences. Opt-out regimens can substantially increase HIV testing, and opt

Magnetocrystalline anisotropy in cobalt based magnets: a choice of correlation parameters and the relativistic effects

DOE PAGES

Nguyen, Manh Cuong; Yao, Yongxin; Wang, Cai-Zhuang; ...

2018-05-16

The dependence of the magnetocrystalline anisotropy energy (MAE) in MCo 5 (M = Y, La, Ce, Gd) and CoPt on the Coulomb correlations and strength of spin orbit (SO) interaction within the GGA + U scheme is investigated. A range of parameters suitable for the satisfactory description of key magnetic properties is determined. We show that for a large variation of SO interaction the MAE in these materials can be well described by the traditional second order perturbation theory. We also show that in these materials the MAE can be both proportional and negatively proportional to the orbital moment anisotropymore » (OMA) of Co atoms. Dependence of relativistic effects on Coulomb correlations, applicability of the second order perturbation theory for the description of MAE, and effective screening of the SO interaction in these systems are discussed using a generalized virial theorem. Finally, such determined sets of parameters of Coulomb correlations can be used in much needed large scale atomistic simulations.« less

Magnetocrystalline anisotropy in cobalt based magnets: a choice of correlation parameters and the relativistic effects

NASA Astrophysics Data System (ADS)

Nguyen, Manh Cuong; Yao, Yongxin; Wang, Cai-Zhuang; Ho, Kai-Ming; Antropov, Vladimir P.

2018-05-01

The dependence of the magnetocrystalline anisotropy energy (MAE) in MCo5 (M  =  Y, La, Ce, Gd) and CoPt on the Coulomb correlations and strength of spin orbit (SO) interaction within the GGA  +  U scheme is investigated. A range of parameters suitable for the satisfactory description of key magnetic properties is determined. We show that for a large variation of SO interaction the MAE in these materials can be well described by the traditional second order perturbation theory. We also show that in these materials the MAE can be both proportional and negatively proportional to the orbital moment anisotropy (OMA) of Co atoms. Dependence of relativistic effects on Coulomb correlations, applicability of the second order perturbation theory for the description of MAE, and effective screening of the SO interaction in these systems are discussed using a generalized virial theorem. Such determined sets of parameters of Coulomb correlations can be used in much needed large scale atomistic simulations.

Magnetocrystalline anisotropy in cobalt based magnets: a choice of correlation parameters and the relativistic effects

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

Nguyen, Manh Cuong; Yao, Yongxin; Wang, Cai-Zhuang

The dependence of the magnetocrystalline anisotropy energy (MAE) in MCo 5 (M = Y, La, Ce, Gd) and CoPt on the Coulomb correlations and strength of spin orbit (SO) interaction within the GGA + U scheme is investigated. A range of parameters suitable for the satisfactory description of key magnetic properties is determined. We show that for a large variation of SO interaction the MAE in these materials can be well described by the traditional second order perturbation theory. We also show that in these materials the MAE can be both proportional and negatively proportional to the orbital moment anisotropymore » (OMA) of Co atoms. Dependence of relativistic effects on Coulomb correlations, applicability of the second order perturbation theory for the description of MAE, and effective screening of the SO interaction in these systems are discussed using a generalized virial theorem. Finally, such determined sets of parameters of Coulomb correlations can be used in much needed large scale atomistic simulations.« less

Uncertainty in dual permeability model parameters for structured soils.

PubMed

Arora, B; Mohanty, B P; McGuire, J T

2012-01-01

Successful application of dual permeability models (DPM) to predict contaminant transport is contingent upon measured or inversely estimated soil hydraulic and solute transport parameters. The difficulty in unique identification of parameters for the additional macropore- and matrix-macropore interface regions, and knowledge about requisite experimental data for DPM has not been resolved to date. Therefore, this study quantifies uncertainty in dual permeability model parameters of experimental soil columns with different macropore distributions (single macropore, and low- and high-density multiple macropores). Uncertainty evaluation is conducted using adaptive Markov chain Monte Carlo (AMCMC) and conventional Metropolis-Hastings (MH) algorithms while assuming 10 out of 17 parameters to be uncertain or random. Results indicate that AMCMC resolves parameter correlations and exhibits fast convergence for all DPM parameters while MH displays large posterior correlations for various parameters. This study demonstrates that the choice of parameter sampling algorithms is paramount in obtaining unique DPM parameters when information on covariance structure is lacking, or else additional information on parameter correlations must be supplied to resolve the problem of equifinality of DPM parameters. This study also highlights the placement and significance of matrix-macropore interface in flow experiments of soil columns with different macropore densities. Histograms for certain soil hydraulic parameters display tri-modal characteristics implying that macropores are drained first followed by the interface region and then by pores of the matrix domain in drainage experiments. Results indicate that hydraulic properties and behavior of the matrix-macropore interface is not only a function of saturated hydraulic conductivity of the macroporematrix interface ( K sa ) and macropore tortuosity ( l f ) but also of other parameters of the matrix and macropore domains.

Uncertainty in dual permeability model parameters for structured soils

NASA Astrophysics Data System (ADS)

Arora, B.; Mohanty, B. P.; McGuire, J. T.

2012-01-01

Successful application of dual permeability models (DPM) to predict contaminant transport is contingent upon measured or inversely estimated soil hydraulic and solute transport parameters. The difficulty in unique identification of parameters for the additional macropore- and matrix-macropore interface regions, and knowledge about requisite experimental data for DPM has not been resolved to date. Therefore, this study quantifies uncertainty in dual permeability model parameters of experimental soil columns with different macropore distributions (single macropore, and low- and high-density multiple macropores). Uncertainty evaluation is conducted using adaptive Markov chain Monte Carlo (AMCMC) and conventional Metropolis-Hastings (MH) algorithms while assuming 10 out of 17 parameters to be uncertain or random. Results indicate that AMCMC resolves parameter correlations and exhibits fast convergence for all DPM parameters while MH displays large posterior correlations for various parameters. This study demonstrates that the choice of parameter sampling algorithms is paramount in obtaining unique DPM parameters when information on covariance structure is lacking, or else additional information on parameter correlations must be supplied to resolve the problem of equifinality of DPM parameters. This study also highlights the placement and significance of matrix-macropore interface in flow experiments of soil columns with different macropore densities. Histograms for certain soil hydraulic parameters display tri-modal characteristics implying that macropores are drained first followed by the interface region and then by pores of the matrix domain in drainage experiments. Results indicate that hydraulic properties and behavior of the matrix-macropore interface is not only a function of saturated hydraulic conductivity of the macroporematrix interface (Ksa) and macropore tortuosity (lf) but also of other parameters of the matrix and macropore domains.

Editor's Choice Offered as a Service

NASA Astrophysics Data System (ADS)

Richman, Barbara T.

2010-06-01

Editor's Choice is now being offered as a service rather than on a subscription basis. As in the past, articles will be selected by collection editors with assistance from advisory panels. The selected articles will be listed on the AGU Web site (http://www.agu.org/pubs/journals/virtual/editors_choice/); these lists will be accessible to anyone. Those who are interested in reading the articles can access them through a personal or institutional subscription or can purchase them either individually or as part of a MultiChoice packet.

Attraction Effect in Risky Choice Can Be Explained by Subjective Distance Between Choice Alternatives.

PubMed

Mohr, Peter N C; Heekeren, Hauke R; Rieskamp, Jörg

2017-08-21

Individuals make decisions under risk throughout daily life. Standard models of economic decision making typically assume that people evaluate choice options independently. There is, however, substantial evidence showing that this independence assumption is frequently violated in decision making without risk. The present study extends these findings to the domain of decision making under risk. To explain the independence violations, we adapted a sequential sampling model, namely Multialternative Decision Field Theory (MDFT), to decision making under risk and showed how this model can account for the observed preference shifts. MDFT not only better predicts choices compared with the standard Expected Utility Theory, but it also explains individual differences in the size of the observed context effect. Evidence in favor of the chosen option, as predicted by MDFT, was positively correlated with brain activity in the medial orbitofrontal cortex (mOFC) and negatively correlated with brain activity in the anterior insula (aINS). From a neuroscience perspective, the results of the present study show that specific brain regions, such as the mOFC and aINS, not only code the value or risk of a single choice option but also code the evidence in favor of the best option compared with other available choice options.

The survival of the pro-choice movement.

PubMed

Staggenborg, S

1995-01-01

In the US, the pro-choice movement has not only survived but grown stronger in the 25 years since the legalization of abortion provided its greatest victory. This longevity is explained through an examination of the internal organizational changes which have taken place in the movement as well as the external changes which have taken place in the political environment surrounding the movement. After providing a theoretical basis for this investigation, the history of the pro-choice movement in the US is traced in light of these elements. In the pre-1973 era, the movement lacked formal organization but was bolstered by external political factors provided by the protest cycle of the 1960s. During 1973-76, the actions of anti-abortion groups forced pro-choice groups to develop the more formalized organizational structures which helped the pro-choice movement survive its initial success and the decline of the era of protests. In the period 1976-83, the anti-abortion movement achieved passage of the Hyde Amendment banning federal funding of abortions. This victory by the opposition led to an expansion in the pro-choice movement which included the formation of many local reproductive rights organizations. Many of these organizations failed to create formalized structures and, therefore, failed to maintain their impetus to survive. However, NARAL (the National Association for Repeal of Abortion Laws) had adopted a more formalized structure and professional leadership following the Hyde legislation and developed strong, formal connections with its state affiliates while continuing to strengthen grassroots actions. The visible threats to abortion laws mounted by the anti-abortion groups added to NARAL's strength. During 1983-89, the pro-choice movement gained some key victories which threatened its survival. Continued activity on the part of the anti-abortion groups (such as release of the movie "The Silent Scream") generated enough pro-choice support, however, to weather

Risk and Career Choice: Evidence from Turkey

ERIC Educational Resources Information Center

Caner, Asena; Okten, Cagla

2010-01-01

In this paper, we examine the college major choice decision in a risk and return framework using university entrance exam data from Turkey. Specifically we focus on the choice between majors with low income risk such as education and health and others with riskier income streams. We use a unique dataset that allows us to control for the choice set…

Science with Constellation-X, Choice of Instrumentation

NASA Technical Reports Server (NTRS)

Hornscheimeier, Ann; White, Nicholas; Tananbaum, Harvey; Garcia, Michael; Bookbinder, Jay; Petre, Robert; Cottam, Jean

2007-01-01

The Constellation X-ray Observatory is one of the two Beyond Einstein Great Observatories and will provide a 100-fold increase in collecting area in high spectral resolving power X-ray instruments over the Chandra and XMM-Newton gratings instruments. The mission has four main science objectives which drive the requirements for the mission. This contribution to the Garmire celebration conference describes these four science areas: Black Holes, Dark Energy, Missing Baryons, and the Neutron Star Equation of State as well as the requirements flow-down that give rise to the choice of instrumentation and implementation for Constellation-X. As we show, each of these science areas place complementary constraints on mission performance parameters such as collecting area, spectral resolving power, timing resolution, and field of view. The mission's capabilities will enable a great breadth of science, and its resources will be open to the community through its General Observer program.

Food Choice Architecture: An Intervention in a Secondary School and its Impact on Students' Plant-based Food Choices.

PubMed

Ensaff, Hannah; Homer, Matt; Sahota, Pinki; Braybrook, Debbie; Coan, Susan; McLeod, Helen

2015-06-02

With growing evidence for the positive health outcomes associated with a plant-based diet, the study's purpose was to examine the potential of shifting adolescents' food choices towards plant-based foods. Using a real world setting of a school canteen, a set of small changes to the choice architecture was designed and deployed in a secondary school in Yorkshire, England. Focussing on designated food items (whole fruit, fruit salad, vegetarian daily specials, and sandwiches containing salad) the changes were implemented for six weeks. Data collected on students' food choice (218,796 transactions) enabled students' (980 students) selections to be examined. Students' food choice was compared for three periods: baseline (29 weeks); intervention (six weeks); and post-intervention (three weeks). Selection of designated food items significantly increased during the intervention and post-intervention periods, compared to baseline (baseline, 1.4%; intervention 3.0%; post-intervention, 2.2%) χ(2)(2) = 68.1, p < 0.001. Logistic regression modelling also revealed the independent effect of the intervention, with students 2.5 times as likely (p < 0.001) to select the designated food items during the intervention period, compared to baseline. The study's results point to the influence of choice architecture within secondary school settings, and its potential role in improving adolescents' daily food choices.

Mother doesn't always know best: Maternal wormlion choice of oviposition habitat does not match larval habitat choice.

PubMed

Adar, Shay; Dor, Roi

2018-02-01

Habitat choice is an important decision that influences animals' fitness. Insect larvae are less mobile than the adults. Consequently, the contribution of the maternal choice of habitat to the survival and development of the offspring is considered to be crucial. According to the "preference-performance hypothesis", ovipositing females are expected to choose habitats that will maximize the performance of their offspring. We tested this hypothesis in wormlions (Diptera: Vermileonidae), which are small sand-dwelling insects that dig pit-traps in sandy patches and ambush small arthropods. Larvae prefer relatively deep and obstacle-free sand, and here we tested the habitat preference of the ovipositing female. In contrast to our expectation, ovipositing females showed no clear preference for either a deep sand or obstacle-free habitat, in contrast to the larval choice. This suboptimal female choice led to smaller pits being constructed later by the larvae, which may reduce prey capture success of the larvae. We offer several explanations for this apparently suboptimal female behavior, related either to maximizing maternal rather than offspring fitness, or to constraints on the female's behavior. Female's ovipositing habitat choice may have weaker negative consequences than expected for the offspring, as larvae can partially correct suboptimal maternal choice. Copyright © 2017 Elsevier B.V. All rights reserved.

Phenotypic plasticity in female mate choice behavior is mediated by an interaction of direct and indirect genetic effects in Drosophila melanogaster.

PubMed

Filice, David C S; Long, Tristan A F

2017-05-01

Female mate choice is a complex decision-making process that involves many context-dependent factors. In Drosophila melanogaster , a model species for the study of sexual selection, indirect genetic effects (IGEs) of general social interactions can influence female mate choice behaviors, but the potential impacts of IGEs associated with mating experiences are poorly understood. Here, we examined whether the IGEs associated with a previous mating experience had an effect on subsequent female mate choice behaviors and quantified the degree of additive genetic variation associated with this effect. Females from 21 different genetic backgrounds were housed with males from one of two distinct genetic backgrounds for either a short (3 hr) or long (48 hr) exposure period and their subsequent mate choice behaviors were scored. We found that the genetic identity of a previous mate significantly influenced a female's subsequent interest in males and preference of males. Additionally, a hemiclonal analysis revealed significant additive genetic variation associated with experience-dependent mate choice behaviors, indicating a genotype-by-environment interaction for both of these parameters. We discuss the significance of these results with regard to the evolution of plasticity in female mate choice behaviors and the maintenance of variation in harmful male traits.

The Social Geography of Choice: Neighborhoods' Role in Students' Navigation of School Choice Policy in Chicago

ERIC Educational Resources Information Center

Phillippo, Kate L.; Griffin, Briellen

2016-01-01

This study extends research on school choice policy, and on the geography of educational opportunity, by exploring how students understand their school choices and select from them within social-geographical space. Using a conceptual framework that draws from situated social cognition and recent research on neighborhood effects, this study…

Factors affecting food choices of older adults from high and low socioeconomic groups: a discrete choice experiment.

PubMed

Kamphuis, Carlijn B M; de Bekker-Grob, Esther W; van Lenthe, Frank J

2015-04-01

Healthiness, price, and convenience are typically indicated as important motives for food choices; however, it is largely unknown to what extent older adults from high and low socioeconomic groups differ in these underlying motives. A discrete choice experiment (DCE) is an innovative way to elicit implicit motives for food choices. The aim was to investigate differences in food motives between socioeconomic groups by means of a DCE. A DCE was carried out during a face-to-face interview among older adults as part of the Health and Living Conditions in Eindhoven and surrounding cities (GLOBE) cohort study, The Netherlands. Participants (n = 399; mean age: 63.3 y) were offered a series of choice sets about a usual dinner at home and were asked to choose in each choice set between 2 meals and an opt-out choice, with different combinations of attribute levels. We included 5 meal attributes (taste, healthiness, preparation time, travel time to shops, and price) and 3 or 4 levels for each attribute. Data were analyzed by multinomial logit models. Healthiness, taste, price, and travel time to the grocery store proved to significantly influence older adults' meal decisions; preparation time was not significant. Healthiness was the most important attribute for all of the participants. More highly educated participants rated a healthy and less expensive meal to be more important than did less educated participants. Those with a high income rated a meal that was healthy and very tasteful to be more important than did those with a lower income. Healthiness, taste, price, and travel time to grocery shops influenced older adults' meal decisions. Higher socioeconomic groups valued health more than did lower socioeconomic groups. DCEs represent a promising method to gain insight into the relative importance of motives for food choices. This trial was registered at www.isrctn.com as ISRCTN60293770. © 2015 American Society for Nutrition.

Exploring the impact of walk–bike infrastructure, safety perception, and built-environment on active transportation mode choice: a random parameter model using New York City commuter data

DOE PAGES

Aziz, H. M. Abdul; Nagle, Nicholas N.; Morton, April M.; ...

2017-02-06

Here, this study finds the effects of traffic safety, walk-bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk-bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the localmore » authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Furthermore, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The findings will help to make smart investment decisions in context of building sustainable transportation systems accounting for active transportation.« less

Exploring the impact of walk–bike infrastructure, safety perception, and built-environment on active transportation mode choice: a random parameter model using New York City commuter data

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

Aziz, H. M. Abdul; Nagle, Nicholas N.; Morton, April M.

Here, this study finds the effects of traffic safety, walk-bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk-bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the localmore » authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Furthermore, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The findings will help to make smart investment decisions in context of building sustainable transportation systems accounting for active transportation.« less

Enhancing Consumer Choice: Are We Making Appropriate Recommendations?

ERIC Educational Resources Information Center

Lee, Jinkook; Geistfeld, Loren V.

1998-01-01

This study used conjoint analysis to identify consumer choice models. Results suggest a need to base choice-making aids on ideal choice models if the aid is to lead consumers to decisions consistent with true preferences. (Author/JOW)

Women's Preferences for Place of Delivery in Rural Tanzania: A Population-Based Discrete Choice Experiment

PubMed Central

Paczkowski, Magdalena; Mbaruku, Godfrey; de Pinho, Helen; Galea, Sandro

2009-01-01

Objectives. We fielded a population-based discrete choice experiment (DCE) in rural western Tanzania, where only one third of women deliver children in a health facility, to evaluate health-system factors that influence women's delivery decisions. Methods. Women were shown choice cards that described 2 hypothetical health centers by means of 6 attributes (distance, cost, type of provider, attitude of provider, drugs and equipment, free transport). The women were then asked to indicate which of the 2 facilities they would prefer to use for a future delivery. We used a hierarchical Bayes procedure to estimate individual and mean utility parameters. Results. A total of 1203 women completed the DCE. The model showed good predictive validity for actual facility choice. The most important facility attributes were a respectful provider attitude and availability of drugs and medical equipment. Policy simulations suggested that if these attributes were improved at existing facilities, the proportion of women preferring facility delivery would rise from 43% to 88%. Conclusions. In regions in which attended delivery rates are low despite availability of primary care facilities, policy experiments should test the effect of targeted quality improvements on facility use. PMID:19608959

Single-particle strength from nucleon transfer in oxygen isotopes: Sensitivity to model parameters

NASA Astrophysics Data System (ADS)

Flavigny, F.; Keeley, N.; Gillibert, A.; Obertelli, A.

2018-03-01

In the analysis of transfer reaction data to extract nuclear structure information the choice of input parameters to the reaction model such as distorting potentials and overlap functions has a significant impact. In this paper we consider a set of data for the (d ,t ) and (d ,3He ) reactions on 14,16,18O as a well-delimited subject for a study of the sensitivity of such analyses to different choices of distorting potentials and overlap functions with particular reference to a previous investigation of the variation of valence nucleon correlations as a function of the difference in nucleon separation energy Δ S =| Sp-Sn| [Phys. Rev. Lett. 110, 122503 (2013), 10.1103/PhysRevLett.110.122503].

What We Know about School Choice.

ERIC Educational Resources Information Center

Froese-Germain, Bernie

1998-01-01

School choice is a market-driven reform in which schools compete for students. Discusses characteristics of choice and lessons drawn from the international experience: increased segregation, unimproved learning, low participation, parental criteria, inequity, lack of options, administrative emphasis on management, and right-wing support. Describes…

Personality Differences in Career Choice Patterns

ERIC Educational Resources Information Center

Borges, Nicole J.; Roth, Karl S.; Seibel, Hugo R.

2004-01-01

Vocational identity is an important construct for physician career development. Physician vocational development has been grouped into three tasks (crystallization, specification, and implementation) pertaining to career choice and specialty choice (1) In defining the construct of vocational identity, it has been suggested that the relation…

True Private Choice: A Practical Guide to School Choice after Zelman v. Simmons-Harris. Policy Analysis.

ERIC Educational Resources Information Center

Gryphon, Marie

In 2002, the Supreme court upheld an Ohio school choice program designed to help children leave Cleveland's failing public schools. This paper explains the history of the Cleveland program upheld in Zelman v. Simmons-Harris, describing the rules that the Supreme Court established for school choice. It includes examples and strategy to help…

Autonomous mechanism of internal choice estimate underlies decision inertia.

PubMed

Akaishi, Rei; Umeda, Kazumasa; Nagase, Asako; Sakai, Katsuyuki

2014-01-08

Our choice is influenced by choices we made in the past, but the mechanism responsible for the choice bias remains elusive. Here we show that the history-dependent choice bias can be explained by an autonomous learning rule whereby an estimate of the likelihood of a choice to be made is updated in each trial by comparing between the actual and expected choices. We found that in perceptual decision making without performance feedback, a decision on an ambiguous stimulus is repeated on the subsequent trial more often than a decision on a salient stimulus. This inertia of decision was not accounted for by biases in motor response, sensory processing, or attention. The posterior cingulate cortex and frontal eye field represent choice prediction error and choice estimate in the learning algorithm, respectively. Interactions between the two regions during the intertrial interval are associated with decision inertia on a subsequent trial. Copyright © 2014 Elsevier Inc. All rights reserved.

Choices Matter, but How Do We Model Them?

NASA Astrophysics Data System (ADS)

Brelsford, C.; Dumas, M.

2017-12-01

Quantifying interactions between social systems and the physical environment we live within has long been a major scientific challenge. Humans have had such a large influence on our environment that it is no longer reasonable to consider the behavior of an ecological or hydrological system from a purely `physical' perspective: imagining a system that excludes the influence of human choices and behavior. Understanding the role that human social choices play in the energy water nexus is crucial for developing accurate models in that space. The relatively new field of socio-hydrology is making progress towards understanding the role humans play in hydrological systems. While this fact is now widely recognized across the many academic fields that study water systems, we have yet to develop a coherent set of theories for how to model the behavior of these complex and highly interdependent socio-hydrological systems. How should we conceptualize hydrological systems as socio-ecological systems (i.e. system with variables, states, parameters, actors who can control certain variables and a sense of the desirability of states) within which the rigorous study of feedbacks becomes possible? This talk reviews the state of knowledge of how social decisions around water consumption, allocation, and transport influence and are influenced by the physical hydrology that water also moves within. We cover recent papers in socio-hydrology, engineering, water law, and institutional analysis. There have been several calls within socio-hydrology to model human social behavior endogenously along with the hydrology. These improvements are needed across a range of spatial and temporal scales. We suggest two potential strategies for coupled models that allow endogenous water consumption behavior: a social first model which looks for empirical relationships between water consumption and allocation choices and the hydrological state, and a hydrology first model in which we look for regularities

Quantum erasure with causally disconnected choice.

PubMed

Ma, Xiao-Song; Kofler, Johannes; Qarry, Angie; Tetik, Nuray; Scheidl, Thomas; Ursin, Rupert; Ramelow, Sven; Herbst, Thomas; Ratschbacher, Lothar; Fedrizzi, Alessandro; Jennewein, Thomas; Zeilinger, Anton

2013-01-22

The counterintuitive features of quantum physics challenge many common-sense assumptions. In an interferometric quantum eraser experiment, one can actively choose whether or not to erase which-path information (a particle feature) of one quantum system and thus observe its wave feature via interference or not by performing a suitable measurement on a distant quantum system entangled with it. In all experiments performed to date, this choice took place either in the past or, in some delayed-choice arrangements, in the future of the interference. Thus, in principle, physical communications between choice and interference were not excluded. Here, we report a quantum eraser experiment in which, by enforcing Einstein locality, no such communication is possible. This is achieved by independent active choices, which are space-like separated from the interference. Our setup employs hybrid path-polarization entangled photon pairs, which are distributed over an optical fiber link of 55 m in one experiment, or over a free-space link of 144 km in another. No naive realistic picture is compatible with our results because whether a quantum could be seen as showing particle- or wave-like behavior would depend on a causally disconnected choice. It is therefore suggestive to abandon such pictures altogether.

Referential Choice: Predictability and Its Limits

PubMed Central

Kibrik, Andrej A.; Khudyakova, Mariya V.; Dobrov, Grigory B.; Linnik, Anastasia; Zalmanov, Dmitrij A.

2016-01-01

We report a study of referential choice in discourse production, understood as the choice between various types of referential devices, such as pronouns and full noun phrases. Our goal is to predict referential choice, and to explore to what extent such prediction is possible. Our approach to referential choice includes a cognitively informed theoretical component, corpus analysis, machine learning methods and experimentation with human participants. Machine learning algorithms make use of 25 factors, including referent’s properties (such as animacy and protagonism), the distance between a referential expression and its antecedent, the antecedent’s syntactic role, and so on. Having found the predictions of our algorithm to coincide with the original almost 90% of the time, we hypothesized that fully accurate prediction is not possible because, in many situations, more than one referential option is available. This hypothesis was supported by an experimental study, in which participants answered questions about either the original text in the corpus, or about a text modified in accordance with the algorithm’s prediction. Proportions of correct answers to these questions, as well as participants’ rating of the questions’ difficulty, suggested that divergences between the algorithm’s prediction and the original referential device in the corpus occur overwhelmingly in situations where the referential choice is not categorical. PMID:27721800

Quantum erasure with causally disconnected choice

PubMed Central

Ma, Xiao-Song; Kofler, Johannes; Qarry, Angie; Tetik, Nuray; Scheidl, Thomas; Ursin, Rupert; Ramelow, Sven; Herbst, Thomas; Ratschbacher, Lothar; Fedrizzi, Alessandro; Jennewein, Thomas; Zeilinger, Anton

2013-01-01

The counterintuitive features of quantum physics challenge many common-sense assumptions. In an interferometric quantum eraser experiment, one can actively choose whether or not to erase which-path information (a particle feature) of one quantum system and thus observe its wave feature via interference or not by performing a suitable measurement on a distant quantum system entangled with it. In all experiments performed to date, this choice took place either in the past or, in some delayed-choice arrangements, in the future of the interference. Thus, in principle, physical communications between choice and interference were not excluded. Here, we report a quantum eraser experiment in which, by enforcing Einstein locality, no such communication is possible. This is achieved by independent active choices, which are space-like separated from the interference. Our setup employs hybrid path-polarization entangled photon pairs, which are distributed over an optical fiber link of 55 m in one experiment, or over a free-space link of 144 km in another. No naive realistic picture is compatible with our results because whether a quantum could be seen as showing particle- or wave-like behavior would depend on a causally disconnected choice. It is therefore suggestive to abandon such pictures altogether. PMID:23288900

Effects of fictive reward on rat's choice behavior

PubMed Central

Kim, Ko-Un; Huh, Namjung; Jang, Yunsil; Lee, Daeyeol; Jung, Min Whan

2015-01-01

Choices of humans and non-human primates are influenced by both actually experienced and fictive outcomes. To test whether this is also the case in rodents, we examined rat's choice behavior in a binary choice task in which variable magnitudes of actual and fictive rewards were delivered. We found that the animal's choice was significantly influenced by the magnitudes of both actual and fictive rewards in the previous trial. A model-based analysis revealed, however, that the effect of fictive reward was more transient and influenced mostly the choice in the next trial, whereas the effect of actual reward was more sustained, consistent with incremental learning of action values. Our results suggest that the capacity to modify future choices based on fictive outcomes might be shared by many different animal species, but fictive outcomes are less effective than actual outcomes in the incremental value learning system. PMID:25623929

Dynamics of memory-guided choice behavior in Drosophila

PubMed Central

ICHINOSE, Toshiharu; TANIMOTO, Hiromu

2016-01-01

Memory retrieval requires both accuracy and speed. Olfactory learning of the fruit fly Drosophila melanogaster serves as a powerful model system to identify molecular and neuronal substrates of memory and memory-guided behavior. The behavioral expression of olfactory memory has traditionally been tested as a conditioned odor response in a simple T-maze, which measures the result, but not the speed, of odor choice. Here, we developed multiplexed T-mazes that allow video recording of the choice behavior. Automatic fly counting in each arm of the maze visualizes choice dynamics. Using this setup, we show that the transient blockade of serotonergic neurons slows down the choice, while leaving the eventual choice intact. In contrast, activation of the same neurons impairs the eventual performance leaving the choice speed unchanged. Our new apparatus contributes to elucidating how the speed and the accuracy of memory retrieval are implemented in the fly brain. PMID:27725473

Acoustic parameters inversion and sediment properties in the Yellow River reservoir

NASA Astrophysics Data System (ADS)

Li, Chang-Zheng; Yang, Yong; Wang, Rui; Yan, Xiao-Fei

2018-03-01

The physical properties of silt in river reservoirs are important to river dynamics. Unfortunately, traditional techniques yield insufficient data. Based on porous media acoustic theory, we invert the acoustic parameters for the top river-bottom sediments. An explicit form of the acoustic reflection coefficient at the water-sediment interface is derived based on Biot's theory. The choice of parameters in the Biot model is discussed and the relation between acoustic and geological parameters is studied, including that between the reflection coefficient and porosity and the attenuation coefficient and permeability. The attenuation coefficient of the sound wave in the sediments is obtained by analyzing the shift of the signal frequency. The acoustic reflection coefficient at the water-sediment interface is extracted from the sonar signal. Thus, an inversion method of the physical parameters of the riverbottom surface sediments is proposed. The results of an experiment at the Sanmenxia reservoir suggest that the estimated grain size is close to the actual data. This demonstrates the ability of the proposed method to determine the physical parameters of sediments and estimate the grain size.

Food Choice Architecture: An Intervention in a Secondary School and its Impact on Students’ Plant-based Food Choices

PubMed Central

Ensaff, Hannah; Homer, Matt; Sahota, Pinki; Braybrook, Debbie; Coan, Susan; McLeod, Helen

2015-01-01

With growing evidence for the positive health outcomes associated with a plant-based diet, the study’s purpose was to examine the potential of shifting adolescents’ food choices towards plant-based foods. Using a real world setting of a school canteen, a set of small changes to the choice architecture was designed and deployed in a secondary school in Yorkshire, England. Focussing on designated food items (whole fruit, fruit salad, vegetarian daily specials, and sandwiches containing salad) the changes were implemented for six weeks. Data collected on students’ food choice (218,796 transactions) enabled students’ (980 students) selections to be examined. Students’ food choice was compared for three periods: baseline (29 weeks); intervention (six weeks); and post-intervention (three weeks). Selection of designated food items significantly increased during the intervention and post-intervention periods, compared to baseline (baseline, 1.4%; intervention 3.0%; post-intervention, 2.2%) χ2(2) = 68.1, p < 0.001. Logistic regression modelling also revealed the independent effect of the intervention, with students 2.5 times as likely (p < 0.001) to select the designated food items during the intervention period, compared to baseline. The study’s results point to the influence of choice architecture within secondary school settings, and its potential role in improving adolescents’ daily food choices. PMID:26043039

Future perspective and healthy lifestyle choices in adulthood.

PubMed

Tasdemir-Ozdes, Aylin; Strickland-Hughes, Carla M; Bluck, Susan; Ebner, Natalie C

2016-09-01

Regardless of age, making healthy lifestyle choices is prudent. Despite that, individuals of all ages sometimes have difficulty choosing the healthy option. We argue that individuals' view of the future and position in the life span affects their current lifestyle choices. We capture the multidimensionality of future thinking by assessing 3 types of future perspective. Younger and older men and women (N = 127) reported global future time perspective, future health perspective, and perceived importance of future health-related events. They also rated their likelihood of making healthy lifestyle choices. As predicted, older participants indicated greater intention to make healthy choices in their current life than did younger participants. Compared to younger participants, older participants reported shorter global future time perspective and anticipated worse future health but perceived future health-related events as more important. Having a positive view of one's future health and seeing future health-related events as important were related to greater intention to make healthy lifestyle choices, but greater global future time perspective was not directly related to healthy choices. However, follow-up analyses suggested that greater global future time perspective indirectly affected healthy choices via a more positive view of future health. None of these relations were moderated by age. Individuals' perspective on the future is shown to be an important multidimensional construct affecting everyday healthy lifestyle choices for both younger and older adults. Implications for encouraging healthy choices across the adult life span are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Food choice patterns among frail older adults: The associations between social network, food choice values, and diet quality.

PubMed

Kim, Chang-O

2016-01-01

Social network type might affect an individual's food choice because these decisions are often made as a group rather than individually. In this study, the associations between social network type, food choice value, and diet quality in frail older adults with low socioeconomic status were investigated. For this cross-sectional study, 87 frail older adults were recruited from the National Home Healthcare Services in Seoul, South Korea. Social network types, food choice values, and diet quality were assessed using The Practitioner Assessment of Network Type Instrument, The Food Choice Questionnaire, and mean adequacy ratio, respectively. Results showed that frail older adults with close relationships with local family and/or friends and neighbors were less likely to follow their own preferences, such as taste, price, and beliefs regarding food health values. In contrast, frail older adults with a small social network and few community contacts were more likely to be influenced by their food choice values, such as price or healthiness of food. Frail older adults who tend to choose familiar foods were associated with low-quality dietary intake, while older adults who valued healthiness or use of natural ingredients were associated with a high-quality diet. The strength and direction of these associations were dependent on social network type of frail older adults. This study explored the hypothesis that food choice values are associated with a certain type of social network and consequently affect diet quality. While additional research needs to be conducted, community-based intervention intended to improve diet quality of frail older adults must carefully consider individual food choice values as well as social network types. Copyright © 2015 Elsevier Ltd. All rights reserved.

Factors Influencing Teaching Choice in Turkey

ERIC Educational Resources Information Center

Kilinc, Ahmet; Watt, Helen M. G.; Richardson, Paul W.

2012-01-01

Why choose to become a teacher in Turkey? The authors examined motivations and perceptions among preservice teachers (N = 1577) encompassing early childhood, primary and secondary education. The Factors Influencing Teaching Choice (FIT-Choice) instrument was translated into Turkish and its construct validity and reliability assessed. Altruistic…

Choice and ego-depletion: the moderating role of autonomy.

PubMed

Moller, Arlen C; Deci, Edward L; Ryan, Richard M

2006-08-01

The self-regulatory strength model maintains that all acts of self-regulation, self-control, and choice result in a state of fatigue called ego-depletion. Self-determination theory differentiates between autonomous regulation and controlled regulation. Because making decisions represents one instance of self-regulation, the authors also differentiate between autonomous choice and controlled choice. Three experiments support the hypothesis that whereas conditions representing controlled choice would be egodepleting, conditions that represented autonomous choice would not. In Experiment 3, the authors found significant mediation by perceived self-determination of the relation between the choice condition (autonomous vs. controlled) and ego-depletion as measured by performance.

A four-alternative forced choice (4AFC) software for observer performance evaluation in radiology

NASA Astrophysics Data System (ADS)

Zhang, Guozhi; Cockmartin, Lesley; Bosmans, Hilde

2016-03-01

Four-alternative forced choice (4AFC) test is a psychophysical method that can be adopted for observer performance evaluation in radiological studies. While the concept of this method is well established, difficulties to handle large image data, perform unbiased sampling, and keep track of the choice made by the observer have restricted its application in practice. In this work, we propose an easy-to-use software that can help perform 4AFC tests with DICOM images. The software suits for any experimental design that follows the 4AFC approach. It has a powerful image viewing system that favorably simulates the clinical reading environment. The graphical interface allows the observer to adjust various viewing parameters and perform the selection with very simple operations. The sampling process involved in 4AFC as well as the speed and accuracy of the choice made by the observer is precisely monitored in the background and can be easily exported for test analysis. The software has also a defensive mechanism for data management and operation control that minimizes the possibility of mistakes from user during the test. This software can largely facilitate the use of 4AFC approach in radiological observer studies and is expected to have widespread applicability.

Choice theories: What are they good for?☆

PubMed Central

Johnson, Eric J.

2013-01-01

Simonson et al. present an ambitious sketch of an integrative theory of context. Provoked by this thoughtful proposal, I discuss what is the function of theories of choice in the coming decades. Traditionally, choice models and theory have attempted to predict choices as a function of the attributes of options. I argue that to be truly useful, they need to generate specific and quantitative predictions of the effect of the choice environment upon choice probability. To do this, we need to focus on rigorously modeling and measuring the underlying processes causing these effects, and use the Simonson et al. proposal to provide some examples. I also present some examples from research in decision-making and decision neuroscience, and argue that models that fail, and fail spectacularly are particularly useful. I close with a challenge: How would consumer researcher aid the design of real world choice environments such as the health exchanges under the Patient Protection and Affordable Care Act? PMID:23794793

Voice and choice by delegation.

PubMed

van de Bovenkamp, Hester; Vollaard, Hans; Trappenburg, Margo; Grit, Kor

2013-02-01

In many Western countries, options for citizens to influence public services are increased to improve the quality of services and democratize decision making. Possibilities to influence are often cast into Albert Hirschman's taxonomy of exit (choice), voice, and loyalty. In this article we identify delegation as an important addition to this framework. Delegation gives individuals the chance to practice exit/choice or voice without all the hard work that is usually involved in these options. Empirical research shows that not many people use their individual options of exit and voice, which could lead to inequality between users and nonusers. We identify delegation as a possible solution to this problem, using Dutch health care as a case study to explore this option. Notwithstanding various advantages, we show that voice and choice by delegation also entail problems of inequality and representativeness.

Choice Rules and Accumulator Networks

PubMed Central

2015-01-01

This article presents a preference accumulation model that can be used to implement a number of different multi-attribute heuristic choice rules, including the lexicographic rule, the majority of confirming dimensions (tallying) rule and the equal weights rule. The proposed model differs from existing accumulators in terms of attribute representation: Leakage and competition, typically applied only to preference accumulation, are also assumed to be involved in processing attribute values. This allows the model to perform a range of sophisticated attribute-wise comparisons, including comparisons that compute relative rank. The ability of a preference accumulation model composed of leaky competitive networks to mimic symbolic models of heuristic choice suggests that these 2 approaches are not incompatible, and that a unitary cognitive model of preferential choice, based on insights from both these approaches, may be feasible. PMID:28670592

Asymmetry of Reinforcement and Punishment in Human Choice

PubMed Central

Rasmussen, Erin B; Newland, M Christopher

2008-01-01

The hypothesis that a penny lost is valued more highly than a penny earned was tested in human choice. Five participants clicked a computer mouse under concurrent variable-interval schedules of monetary reinforcement. In the no-punishment condition, the schedules arranged monetary gain. In the punishment conditions, a schedule of monetary loss was superimposed on one response alternative. Deviations from generalized matching using the free parameters c (sensitivity to reinforcement) and log k (bias) were compared in the no-punishment and punishment conditions. The no-punishment conditions yielded values of log k that approximated zero for all participants, indicating no bias. In the punishment condition, values of log k deviated substantially from zero, revealing a 3-fold bias toward the unpunished alternative. Moreover, the c parameters were substantially smaller in punished conditions. The values for bias and sensitivity under punishment did not change significantly when the measure of net reinforcers (gains minus losses) was applied to the analysis. These results mean that punishment reduced the sensitivity of behavior to reinforcement and biased performance toward the unpunished alternative. We concluded that a single punisher subtracted more value than a single reinforcer added, indicating an asymmetry in the law of effect. PMID:18422016

A meta-learning system based on genetic algorithms

NASA Astrophysics Data System (ADS)

Pellerin, Eric; Pigeon, Luc; Delisle, Sylvain

2004-04-01

The design of an efficient machine learning process through self-adaptation is a great challenge. The goal of meta-learning is to build a self-adaptive learning system that is constantly adapting to its specific (and dynamic) environment. To that end, the meta-learning mechanism must improve its bias dynamically by updating the current learning strategy in accordance with its available experiences or meta-knowledge. We suggest using genetic algorithms as the basis of an adaptive system. In this work, we propose a meta-learning system based on a combination of the a priori and a posteriori concepts. A priori refers to input information and knowledge available at the beginning in order to built and evolve one or more sets of parameters by exploiting the context of the system"s information. The self-learning component is based on genetic algorithms and neural Darwinism. A posteriori refers to the implicit knowledge discovered by estimation of the future states of parameters and is also applied to the finding of optimal parameters values. The in-progress research presented here suggests a framework for the discovery of knowledge that can support human experts in their intelligence information assessment tasks. The conclusion presents avenues for further research in genetic algorithms and their capability to learn to learn.

Analyzing the impact of modeling choices and assumptions in compartmental epidemiological models

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

Nutaro, James J.; Pullum, Laura L.; Ramanathan, Arvind

In this study, computational models have become increasingly used as part of modeling, predicting, and understanding how infectious diseases spread within large populations. These models can be broadly classified into differential equation-based models (EBM) and agent-based models (ABM). Both types of models are central in aiding public health officials design intervention strategies in case of large epidemic outbreaks. We examine these models in the context of illuminating their hidden assumptions and the impact these may have on the model outcomes. Very few ABM/EBMs are evaluated for their suitability to address a particular public health concern, and drawing relevant conclusions aboutmore » their suitability requires reliable and relevant information regarding the different modeling strategies and associated assumptions. Hence, there is a need to determine how the different modeling strategies, choices of various parameters, and the resolution of information for EBMs and ABMs affect outcomes, including predictions of disease spread. In this study, we present a quantitative analysis of how the selection of model types (i.e., EBM vs. ABM), the underlying assumptions that are enforced by model types to model the disease propagation process, and the choice of time advance (continuous vs. discrete) affect the overall outcomes of modeling disease spread. Our study reveals that the magnitude and velocity of the simulated epidemic depends critically on the selection of modeling principles, various assumptions of disease process, and the choice of time advance.« less

Analyzing the impact of modeling choices and assumptions in compartmental epidemiological models

DOE PAGES

Nutaro, James J.; Pullum, Laura L.; Ramanathan, Arvind; ...

2016-05-01

In this study, computational models have become increasingly used as part of modeling, predicting, and understanding how infectious diseases spread within large populations. These models can be broadly classified into differential equation-based models (EBM) and agent-based models (ABM). Both types of models are central in aiding public health officials design intervention strategies in case of large epidemic outbreaks. We examine these models in the context of illuminating their hidden assumptions and the impact these may have on the model outcomes. Very few ABM/EBMs are evaluated for their suitability to address a particular public health concern, and drawing relevant conclusions aboutmore » their suitability requires reliable and relevant information regarding the different modeling strategies and associated assumptions. Hence, there is a need to determine how the different modeling strategies, choices of various parameters, and the resolution of information for EBMs and ABMs affect outcomes, including predictions of disease spread. In this study, we present a quantitative analysis of how the selection of model types (i.e., EBM vs. ABM), the underlying assumptions that are enforced by model types to model the disease propagation process, and the choice of time advance (continuous vs. discrete) affect the overall outcomes of modeling disease spread. Our study reveals that the magnitude and velocity of the simulated epidemic depends critically on the selection of modeling principles, various assumptions of disease process, and the choice of time advance.« less

Search, Memory, and Choice Error: An Experiment

PubMed Central

Sanjurjo, Adam

2015-01-01

Multiple attribute search is a central feature of economic life: we consider much more than price when purchasing a home, and more than wage when choosing a job. An experiment is conducted in order to explore the effects of cognitive limitations on choice in these rich settings, in accordance with the predictions of a new model of search memory load. In each task, subjects are made to search the same information in one of two orders, which differ in predicted memory load. Despite standard models of choice treating such variations in order of acquisition as irrelevant, lower predicted memory load search orders are found to lead to substantially fewer choice errors. An implication of the result for search behavior, more generally, is that in order to reduce memory load (thus choice error) a limited memory searcher ought to deviate from the search path of an unlimited memory searcher in predictable ways-a mechanism that can explain the systematic deviations from optimal sequential search that have recently been discovered in peoples' behavior. Further, as cognitive load is induced endogenously (within the task), and found to affect choice behavior, this result contributes to the cognitive load literature (in which load is induced exogenously), as well as the cognitive ability literature (in which cognitive ability is measured in a separate task). In addition, while the information overload literature has focused on the detrimental effects of the quantity of information on choice, this result suggests that, holding quantity constant, the order that information is observed in is an essential determinant of choice failure. PMID:26121356

Age and choice in health insurance: evidence from a discrete choice experiment.

PubMed

Becker, Karolin; Zweifel, Peter

2008-01-01

A uniform package of benefits and uniform cost sharing are elements of regulation inherent in most social health insurance systems. Both elements risk burdening the population with a welfare loss if preferences for risk and insurance attributes differ. This suggests the introduction of more choice in social health insurance packages may be advantageous; however, it is widely believed that this would not benefit the elderly.A representative telephone survey of 1000 people aged >24 years living in the German- and French-speaking parts of Switzerland was conducted. Participants were asked to compare the status quo (i.e. their current insurance contract) with ten hypothetical alternatives. In addition, participants were asked questions concerning utilization of healthcare services; overall satisfaction with the healthcare system, insurer and insurance policy; and a general preference for new elements in the insurance package. Socioeconomic variables surveyed were age, sex, total household income, education (seven categories ranging from primary school to university degree), place of residence, occupation, and marital status. To examine the relationship between age and willingness to pay (WTP) for additional options in Swiss social health insurance.A representative telephone survey of 1000 people aged >24 years living in the German- and French-speaking parts of Switzerland was conducted. Participants were asked to compare the status quo (i.e. their current insurance contract) with ten hypothetical alternatives. In addition, participants were asked questions concerning utilization of healthcare services; overall satisfaction with the healthcare system, insurer and insurance policy; and a general preference for new elements in the insurance package. Socioeconomic variables surveyed were age, sex, total household income, education (seven categories ranging from primary school to university degree), place of residence, occupation, and marital status. A discrete choice

An aggregate method to calibrate the reference point of cumulative prospect theory-based route choice model for urban transit network

NASA Astrophysics Data System (ADS)

Zhang, Yufeng; Long, Man; Luo, Sida; Bao, Yu; Shen, Hanxia

2015-12-01

Transit route choice model is the key technology of public transit systems planning and management. Traditional route choice models are mostly based on expected utility theory which has an evident shortcoming that it cannot accurately portray travelers' subjective route choice behavior for their risk preferences are not taken into consideration. Cumulative prospect theory (CPT), a brand new theory, can be used to describe travelers' decision-making process under the condition of uncertainty of transit supply and risk preferences of multi-type travelers. The method to calibrate the reference point, a key parameter to CPT-based transit route choice model, determines the precision of the model to a great extent. In this paper, a new method is put forward to obtain the value of reference point which combines theoretical calculation and field investigation results. Comparing the proposed method with traditional method, it shows that the new method can promote the quality of CPT-based model by improving the accuracy in simulating travelers' route choice behaviors based on transit trip investigation from Nanjing City, China. The proposed method is of great significance to logical transit planning and management, and to some extent makes up the defect that obtaining the reference point is solely based on qualitative analysis.

Female Adolescents' Educational Choices about Reproductive Health Modules

ERIC Educational Resources Information Center

Gold, Melanie A.; Chiappetta, Laurel; Young, Amanda J.; Zuckoff, Allan; DiClemente, Carlo C.

2008-01-01

Purpose: To assess girls' reproductive educational choices, satisfaction with choice, and relationship between demographics, module choice, and satisfaction. Methods: We recruited 286 girls, aged 13 to 21 years, from a hospital-based adolescent clinic, from advertisements, and by word of mouth. At enrollment, participants completed a 60-minute…

Health concern, food choice motives, and attitudes toward healthy eating: the mediating role of food choice motives.

PubMed

Sun, Yu-Hua Christine

2008-07-01

This study addresses how various health concerns might influence not only consumers' food choice motives but also consumers' subsequent attitudes toward healthy eating. This study expects that those consumers with greater health concerns would have different food choice motives and better attitudes toward healthy eating. A self-completion questionnaire was used to gather information. Participants, a random sample of 500 undergraduate students from a national university in Taipei, Taiwan, provided a total of 456 usable questionnaires, representing a valid response rate of 91%. The average age of the respondents at the time of the survey was 21 years and 63% of respondents were females. The relationship between health concern and healthy eating attitudes was confirmed. The relationship between health concern of developing diseases and attitudes toward healthy eating was fully mediated by food choice motives. However, the relationship between calorie consumption health concern and healthy eating attitudes was only partially mediated by food choice motives. Implications of these findings are discussed.

Spontaneous prosocial choice by captive bottlenose dolphins, Tursiops truncatus.

PubMed

Nakahara, Fumio; Komaba, Masayuki; Sato, Ryoichi; Ikeda, Hisako; Komaba, Kumiko; Kawakubo, Akihiro

2017-02-01

Dolphins exhibit prosocial behavior across several different contexts. However, only a few experimental studies have investigated the psychological mechanisms underlying this behavior. In this study, we investigated the mechanisms underlying prosociality in bottlenose dolphins (Tursiops truncatus). In the experiments, water shower devices, developed as environmental enrichment items, were used. Two paradigms were used to measure prosociality. The first was the prosocial choice task, involving the subject typically being offered one choice between two options. The first option provided a reward (take a shower) to both the subject and partner (prosocial choice). The second option provided a reward only to the subject (selfish choice). The second paradigm was the giving assistance task, involving the subject being provided a choice between providing instrumental help to the partner (prosocial choice) or doing nothing. It was observed that the subjects chose the prosocial choices in both paradigms. In these experiments, prosocial choices were spontaneously taken without requests from the partners. These results indicated that the dolphins show preference for other-regarding behavior. Copyright © 2016 Elsevier B.V. All rights reserved.

On the impact of large angle CMB polarization data on cosmological parameters

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

Lattanzi, Massimiliano; Mandolesi, Nazzareno; Natoli, Paolo

We study the impact of the large-angle CMB polarization datasets publicly released by the WMAP and Planck satellites on the estimation of cosmological parameters of the ΛCDM model. To complement large-angle polarization, we consider the high resolution (or 'high-ℓ') CMB datasets from either WMAP or Planck as well as CMB lensing as traced by Planck 's measured four point correlation function. In the case of WMAP, we compute the large-angle polarization likelihood starting over from low resolution frequency maps and their covariance matrices, and perform our own foreground mitigation technique, which includes as a possible alternative Planck 353 GHz datamore » to trace polarized dust. We find that the latter choice induces a downward shift in the optical depth τ, roughly of order 2σ, robust to the choice of the complementary high resolution dataset. When the Planck 353 GHz is consistently used to minimize polarized dust emission, WMAP and Planck 70 GHz large-angle polarization data are in remarkable agreement: by combining them we find τ = 0.066 {sup +0.012}{sub −0.013}, again very stable against the particular choice for high-ℓ data. We find that the amplitude of primordial fluctuations A {sub s} , notoriously degenerate with τ, is the parameter second most affected by the assumptions on polarized dust removal, but the other parameters are also affected, typically between 0.5 and 1σ. In particular, cleaning dust with Planck 's 353 GHz data imposes a 1σ downward shift in the value of the Hubble constant H {sub 0}, significantly contributing to the tension reported between CMB based and direct measurements of the present expansion rate. On the other hand, we find that the appearance of the so-called low ℓ anomaly, a well-known tension between the high- and low-resolution CMB anisotropy amplitude, is not significantly affected by the details of large-angle polarization, or by the particular high-ℓ dataset employed.« less

Work Values and College Major Choice

ERIC Educational Resources Information Center

Balsamo, Michela; Lauriola, Marco; Saggino, Aristide

2013-01-01

Our study sought to clarify the nature of the known individual differences in work values associated with academic college major choice, specifically the question whether these precede or follow the choice of an academic major. To rule out environmental influences during academic study, group differences in five value orientations were evaluated…

Career Choice and Development. Third Edition.

ERIC Educational Resources Information Center

Brown, Duane; And Others

This book contains 12 papers examining established and newly emerging theories of career choice and development. Following prefaces to the third, second, and first editions by Duane Brown and Linda Brooks, the following papers are included: "Introduction to Theories of Career Development and Choice: Origins, Evolution, and Current Efforts" (Duane…

Two Philosophical Errors Concerning School Choice.

ERIC Educational Resources Information Center

Brighouse, Harry

1997-01-01

Argues, in contrast to David Hargreaves, that libertarianism implies a mild presumption against school choice, and that notions of common good are significant to educational decision making only when deciding between sets of institutions that perform equally well at delivering their obligations. Links these issues to questions about school choice.…

Computerized Classification Testing under the One-Parameter Logistic Response Model with Ability-Based Guessing

ERIC Educational Resources Information Center

Wang, Wen-Chung; Huang, Sheng-Yun

2011-01-01

The one-parameter logistic model with ability-based guessing (1PL-AG) has been recently developed to account for effect of ability on guessing behavior in multiple-choice items. In this study, the authors developed algorithms for computerized classification testing under the 1PL-AG and conducted a series of simulations to evaluate their…

Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters.

PubMed

Contaldi, Carlo R; Hoekstra, Henk; Lewis, Antony

2003-06-06

We use cosmic microwave background (CMB) observations together with the red-sequence cluster survey weak lensing results to derive constraints on a range of cosmological parameters. This particular choice of observations is motivated by their robust physical interpretation and complementarity. Our combined analysis, including a weak nucleosynthesis constraint, yields accurate determinations of a number of parameters including the amplitude of fluctuations sigma(8)=0.89+/-0.05 and matter density Omega(m)=0.30+/-0.03. We also find a value for the Hubble parameter of H(0)=70+/-3 km s(-1) Mpc(-1), in good agreement with the Hubble Space Telescope key-project result. We conclude that the combination of CMB and weak lensing data provides some of the most powerful constraints available in cosmology today.

Indigenous Parents Navigating School Choice in Constrained Landscapes

ERIC Educational Resources Information Center

Anthony-Stevens, Vanessa

2017-01-01

Educational reform policies in the United States promote school choice as a central tool to empower low-income and minoritized families in order to close the achievement gap. However, research on school choice rarely reflects the voice of minoritized families and offers little evidence that choice significantly addresses inequities in educational…

Embodied Choice: How Action Influences Perceptual Decision Making

PubMed Central

Lepora, Nathan F.; Pezzulo, Giovanni

2015-01-01

Embodied Choice considers action performance as a proper part of the decision making process rather than merely as a means to report the decision. The central statement of embodied choice is the existence of bidirectional influences between action and decisions. This implies that for a decision expressed by an action, the action dynamics and its constraints (e.g. current trajectory and kinematics) influence the decision making process. Here we use a perceptual decision making task to compare three types of model: a serial decision-then-action model, a parallel decision-and-action model, and an embodied choice model where the action feeds back into the decision making. The embodied model incorporates two key mechanisms that together are lacking in the other models: action preparation and commitment. First, action preparation strategies alleviate delays in enacting a choice but also modify decision termination. Second, action dynamics change the prospects and create a commitment effect to the initially preferred choice. Our results show that these two mechanisms make embodied choice models better suited to combine decision and action appropriately to achieve suitably fast and accurate responses, as usually required in ecologically valid situations. Moreover, embodied choice models with these mechanisms give a better account of trajectory tracking experiments during decision making. In conclusion, the embodied choice framework offers a combined theory of decision and action that gives a clear case that embodied phenomena such as the dynamics of actions can have a causal influence on central cognition. PMID:25849349

Embodied choice: how action influences perceptual decision making.

PubMed

Lepora, Nathan F; Pezzulo, Giovanni

2015-04-01

Embodied Choice considers action performance as a proper part of the decision making process rather than merely as a means to report the decision. The central statement of embodied choice is the existence of bidirectional influences between action and decisions. This implies that for a decision expressed by an action, the action dynamics and its constraints (e.g. current trajectory and kinematics) influence the decision making process. Here we use a perceptual decision making task to compare three types of model: a serial decision-then-action model, a parallel decision-and-action model, and an embodied choice model where the action feeds back into the decision making. The embodied model incorporates two key mechanisms that together are lacking in the other models: action preparation and commitment. First, action preparation strategies alleviate delays in enacting a choice but also modify decision termination. Second, action dynamics change the prospects and create a commitment effect to the initially preferred choice. Our results show that these two mechanisms make embodied choice models better suited to combine decision and action appropriately to achieve suitably fast and accurate responses, as usually required in ecologically valid situations. Moreover, embodied choice models with these mechanisms give a better account of trajectory tracking experiments during decision making. In conclusion, the embodied choice framework offers a combined theory of decision and action that gives a clear case that embodied phenomena such as the dynamics of actions can have a causal influence on central cognition.

Choice Grants: Foundations and the School Choice Movement. Edited Transcript

ERIC Educational Resources Information Center

Shaffer, Krista, Ed.

2007-01-01

A National Committee for Responsive Philanthropy (NCRP) report addresses the questions "What have conservative foundations done with their grant dollars to promote concepts of privatizing public education through "school choice," primarily linked to school vouchers? What were their strategies in providing resources to an array of conservative…

Responsibility and School Choice in Education

ERIC Educational Resources Information Center

Colburn, Ben

2012-01-01

Consider the following argument for school choice, based on an appeal to the virtues of the market: allowing parents some measure of choice over their particular children's education ultimately serves the interests of all children, because creating a market mechanism in state education will produce improvements through the same pressures that lead…

Democratic Education and School Choice Revisited

ERIC Educational Resources Information Center

Paquette, Jerry

2005-01-01

This article features the author's reply to John Coons's "Dodging Democracy: The Educator's Flight from the Specter of Choice." First, he wants to thank Coons for his thoughtful and thought-provoking reply to "Public Funding for 'Private' Education: The Equity Challenge of Enhanced Choice." So thought provoking, in fact, did the author find…

Increasing Choice Making in Students with Intellectual Disability

ERIC Educational Resources Information Center

Sparks, Shannon Lynn; Pierce, Tom; Higgins, Kyle; Miller, Susan; Tandy, Richard

2016-01-01

The purpose of this study was to examine the effectiveness of choice-making training with six high school students with intellectual disability. A multiple probe design with one replication was used to evaluate the efficacy of the choice-making training. The results suggest participants increased and maintained their choice-making abilities.…

Bayesian road safety analysis: incorporation of past evidence and effect of hyper-prior choice.

PubMed

Miranda-Moreno, Luis F; Heydari, Shahram; Lord, Dominique; Fu, Liping

2013-09-01

This paper aims to address two related issues when applying hierarchical Bayesian models for road safety analysis, namely: (a) how to incorporate available information from previous studies or past experiences in the (hyper) prior distributions for model parameters and (b) what are the potential benefits of incorporating past evidence on the results of a road safety analysis when working with scarce accident data (i.e., when calibrating models with crash datasets characterized by a very low average number of accidents and a small number of sites). A simulation framework was developed to evaluate the performance of alternative hyper-priors including informative and non-informative Gamma, Pareto, as well as Uniform distributions. Based on this simulation framework, different data scenarios (i.e., number of observations and years of data) were defined and tested using crash data collected at 3-legged rural intersections in California and crash data collected for rural 4-lane highway segments in Texas. This study shows how the accuracy of model parameter estimates (inverse dispersion parameter) is considerably improved when incorporating past evidence, in particular when working with the small number of observations and crash data with low mean. The results also illustrates that when the sample size (more than 100 sites) and the number of years of crash data is relatively large, neither the incorporation of past experience nor the choice of the hyper-prior distribution may affect the final results of a traffic safety analysis. As a potential solution to the problem of low sample mean and small sample size, this paper suggests some practical guidance on how to incorporate past evidence into informative hyper-priors. By combining evidence from past studies and data available, the model parameter estimates can significantly be improved. The effect of prior choice seems to be less important on the hotspot identification. The results show the benefits of incorporating prior

Impact parameter sensitive study of inner-shell atomic processes in the experimental storage ring

NASA Astrophysics Data System (ADS)

Gumberidze, A.; Kozhuharov, C.; Zhang, R. T.; Trotsenko, S.; Kozhedub, Y. S.; DuBois, R. D.; Beyer, H. F.; Blumenhagen, K.-H.; Brandau, C.; Bräuning-Demian, A.; Chen, W.; Forstner, O.; Gao, B.; Gassner, T.; Grisenti, R. E.; Hagmann, S.; Hillenbrand, P.-M.; Indelicato, P.; Kumar, A.; Lestinsky, M.; Litvinov, Yu. A.; Petridis, N.; Schury, D.; Spillmann, U.; Trageser, C.; Trassinelli, M.; Tu, X.; Stöhlker, Th.

2017-10-01

In this work, we present a pilot experiment in the experimental storage ring (ESR) at GSI devoted to impact parameter sensitive studies of inner shell atomic processes for low-energy (heavy-) ion-atom collisions. The experiment was performed with bare and He-like xenon ions (Xe54+, Xe52+) colliding with neutral xenon gas atoms, resulting in a symmetric collision system. This choice of the projectile charge states was made in order to compare the effect of a filled K-shell with the empty one. The projectile and target X-rays have been measured at different observation angles for all impact parameters as well as for the impact parameter range of ∼35-70 fm.

Genetic determination of height-mediated mate choice.

PubMed

Tenesa, Albert; Rawlik, Konrad; Navarro, Pau; Canela-Xandri, Oriol

2016-01-19

Numerous studies have reported positive correlations among couples for height. This suggests that humans find individuals of similar height attractive. However, the answer to whether the choice of a mate with a similar phenotype is genetically or environmentally determined has been elusive. Here we provide an estimate of the genetic contribution to height choice in mates in 13,068 genotyped couples. Using a mixed linear model we show that 4.1% of the variation in the mate height choice is determined by a person's own genotype, as expected in a model where one's height determines the choice of mate height. Furthermore, the genotype of an individual predicts their partners' height in an independent dataset of 15,437 individuals with 13% accuracy, which is 64% of the theoretical maximum achievable with a heritability of 0.041. Theoretical predictions suggest that approximately 5% of the heritability of height is due to the positive covariance between allelic effects at different loci, which is caused by assortative mating. Hence, the coupling of alleles with similar effects could substantially contribute to the missing heritability of height. These estimates provide new insight into the mechanisms that govern mate choice in humans and warrant the search for the genetic causes of choice of mate height. They have important methodological implications and contribute to the missing heritability debate.

Understanding Predisposition in College Choice: Toward an Integrated Model of College Choice and Theory of Reasoned Action

ERIC Educational Resources Information Center

Pitre, Paul E.; Johnson, Todd E.; Pitre, Charisse Cowan

2006-01-01

This article seeks to improve traditional models of college choice that draw from recruitment and enrollment management paradigms. In adopting a consumer approach to college choice, this article seeks to build upon consumer-related research, which centers on behavior and reasoning. More specifically, this article seeks to move inquiry beyond the…

The impact of choice on young children's prosocial motivation.

PubMed

Rapp, Diotima J; Engelmann, Jan M; Herrmann, Esther; Tomasello, Michael

2017-06-01

The current study explored how freedom of choice affects preschoolers' prosocial motivation. Children (3- and 5-year-olds) participated in either a choice condition (where they could decide for themselves whether to help or not) or a no-choice condition (where they were instructed to help). Prosocial motivation was subsequently assessed by measuring the amount children helped an absent peer in the face of an attractive alternative game. The 5-year-olds provided with choice helped more than the children not provided with choice, and this effect was stronger for girls than for boys. There was no difference between conditions for the 3-year-olds. These results highlight the importance of choice in young children's prosocial development. Copyright © 2017 Elsevier Inc. All rights reserved.

Nudging consumers towards healthier choices: a systematic review of positional influences on food choice.

PubMed

Bucher, Tamara; Collins, Clare; Rollo, Megan E; McCaffrey, Tracy A; De Vlieger, Nienke; Van der Bend, Daphne; Truby, Helen; Perez-Cueto, Federico J A

2016-06-01

Nudging or 'choice architecture' refers to strategic changes in the environment that are anticipated to alter people's behaviour in a predictable way, without forbidding any options or significantly changing their economic incentives. Nudging strategies may be used to promote healthy eating behaviour. However, to date, the scientific evidence has not been systematically reviewed to enable practitioners and policymakers to implement, or argue for the implementation of, specific measures to support nudging strategies. This systematic review investigated the effect of positional changes of food placement on food choice. In total, seven scientific databases were searched using relevant keywords to identify interventions that manipulated food position (proximity or order) to generate a change in food selection, sales or consumption, among normal-weight or overweight individuals across any age group. From 2576 identified articles, fifteen articles comprising eighteen studies met our inclusion criteria. This review has identified that manipulation of food product order or proximity can influence food choice. Such approaches offer promise in terms of impacting on consumer behaviour. However, there is a need for high-quality studies that quantify the magnitude of positional effects on food choice in conjunction with measuring the impact on food intake, particularly in the longer term. Future studies should use outcome measures such as change in grams of food consumed or energy intake to quantify the impact on dietary intake and potential impacts on nutrition-related health. Research is also needed to evaluate potential compensatory behaviours secondary to such interventions.

The role of word choice and criterion on intentional memory.

PubMed

Toyota, Hiroshi

2015-02-01

The relationship between the criterion for choosing and the self-choice effects (greater recall in a self-choice compared to a forced-choice condition) on intentional memory was examined. Thirty-three female nursing school volunteers were administered 24 word pairs in a 2 × 2 design to assess the influence of motivation upon free recall. When word pairs were presented to participants, they were asked to choose a word to-be-remembered, either in a self-choice condition or a forced-choice condition. Words chosen by the participants were recalled more often than those chosen by the experimenter (forced choice). Thus, the self-choice effect was greater for words chosen with a self-reference criterion compared to a metamemory criterion, supporting the integration hypothesis as the origin of the self-choice effect.

The child brain computes and utilizes internalized maternal choices

PubMed Central

Lim, Seung-Lark; Cherry, J. Bradley C.; Davis, Ann M.; Balakrishnan, S. N.; Ha, Oh-Ryeong; Bruce, Jared M.; Bruce, Amanda S.

2016-01-01

As children grow, they gradually learn how to make decisions independently. However, decisions like choosing healthy but less-tasty foods can be challenging for children whose self-regulation and executive cognitive functions are still maturing. We propose a computational decision-making process in which children estimate their mother's choices for them as well as their individual food preferences. By employing functional magnetic resonance imaging during real food choices, we find that the ventromedial prefrontal cortex (vmPFC) encodes children's own preferences and the left dorsolateral prefrontal cortex (dlPFC) encodes the projected mom's choices for them at the time of children's choice. Also, the left dlPFC region shows an inhibitory functional connectivity with the vmPFC at the time of children's own choice. Our study suggests that in part, children utilize their perceived caregiver's choices when making choices for themselves, which may serve as an external regulator of decision-making, leading to optimal healthy decisions. PMID:27218420

Patient choice in opt-in, active choice, and opt-out HIV screening: randomized clinical trial

PubMed Central

Dow, William H; Kaplan, Beth C

2016-01-01

Study question What is the effect of default test offers—opt-in, opt-out, and active choice—on the likelihood of acceptance of an HIV test among patients receiving care in an emergency department? Methods This was a randomized clinical trial conducted in the emergency department of an urban teaching hospital and regional trauma center. Patients aged 13-64 years were randomized to opt-in, opt-out, and active choice HIV test offers. The primary outcome was HIV test acceptance percentage. The Denver Risk Score was used to categorize patients as being at low, intermediate, or high risk of HIV infection. Study answer and limitations 38.0% (611/1607) of patients in the opt-in testing group accepted an HIV test, compared with 51.3% (815/1628) in the active choice arm (difference 13.3%, 95% confidence interval 9.8% to 16.7%) and 65.9% (1031/1565) in the opt-out arm (difference 27.9%, 24.4% to 31.3%). Compared with active choice testing, opt-out testing led to a 14.6 (11.1 to 18.1) percentage point increase in test acceptance. Patients identified as being at intermediate and high risk were more likely to accept testing than were those at low risk in all arms (difference 6.4% (3.4% to 9.3%) for intermediate and 8.3% (3.3% to 13.4%) for high risk). The opt-out effect was significantly smaller among those reporting high risk behaviors, but the active choice effect did not significantly vary by level of reported risk behavior. Patients consented to inclusion in the study after being offered an HIV test, and inclusion varied slightly by treatment assignment. The study took place at a single county hospital in a city that is somewhat unique with respect to HIV testing; although the test acceptance percentages themselves might vary, a different pattern for opt-in versus active choice versus opt-out test schemes would not be expected. What this paper adds Active choice is a distinct test regimen, with test acceptance patterns that may best approximate patients’ true

Emotion regulation choice: the role of environmental affordances.

PubMed

Suri, Gaurav; Sheppes, Gal; Young, Gerald; Abraham, Damon; McRae, Kateri; Gross, James J

2017-09-01

Which emotion regulation strategy one uses in a given context can have profound affective, cognitive, and social consequences. It is therefore important to understand the determinants of emotion regulation choice. Many prior studies have examined person-specific, internal determinants of emotion regulation choice. Recently, it has become clear that external variables that are properties of the stimulus can also influence emotion regulation choice. In the present research, we consider whether reappraisal affordances, defined as the opportunities for re-interpretation of a stimulus that are inherent in that stimulus, can shape individuals' emotion regulation choices. We show that reappraisal affordances have stability across people and across time (Study 1), and are confounded with emotional intensity for a standardised set of picture stimuli (Study 2). Since emotional intensity has been shown to drive emotion regulation choice, we construct a context in which emotional intensity is separable from reappraisal affordances (Study 3) and use this context to show that reappraisal affordances powerfully influence emotion regulation choice even when emotional intensity and discrete emotions are taken into account (Study 4).

College Bound? Make the Right Choices

ERIC Educational Resources Information Center

Robinson, Jenna Ashley

2009-01-01

"College Bound? Make the Right Choices" is the Pope Center's latest tool for improving colleges and universities "from the bottom up" through better choices. Its purpose is to help high school students and their parents become smarter purchasers of higher education. This booklet by Jenna Ashley Robinson helps young people think through what they…

School Choice and the Achievement Gap

ERIC Educational Resources Information Center

Jeynes, William H.

2014-01-01

The possibility is examined that school choice programs could be a means to reducing the achievement gap. Data based on meta-analytic research and the examination of nationwide data sets suggest that school choice programs that include private schools could reduce the achievement gap by 25%. The propounding of this possibility is based on research…

Comparing theories of reference-dependent choice.

PubMed

Bhatia, Sudeep

2017-09-01

Preferences are influenced by the presence or absence of salient choice options, known as reference points. This behavioral tendency is traditionally attributed to the loss aversion and diminishing sensitivity assumptions of prospect theory. In contrast, some psychological research suggests that reference dependence is caused by attentional biases that increase the subjective weighting of the reference point's primary attributes. Although both theories are able to successfully account for behavioral findings involving reference dependence, this article shows that these theories make diverging choice predictions when available options are inferior to the reference point. It presents the results of 2 studies that use settings with inferior choice options to compare these 2 theories. The analysis involves quantitative fits to participant-level choice data, and the results indicate that most participants are better described by models with attentional bias than they are by models with loss aversion and diminishing sensitivity. These differences appear to be caused by violations of loss aversion and diminishing sensitivity in losses. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Choices and changes: Eccles' Expectancy-Value model and upper-secondary school students' longitudinal reflections about their choice of a STEM education

NASA Astrophysics Data System (ADS)

Lykkegaard, Eva; Ulriksen, Lars

2016-03-01

During the past 30 years, Eccles' comprehensive social-psychological Expectancy-Value Model of Motivated Behavioural Choices (EV-MBC model) has been proven suitable for studying educational choices related to Science, Technology, Engineering and/or Mathematics (STEM). The reflections of 15 students in their last year in upper-secondary school concerning their choice of tertiary education were examined using quantitative EV-MBC surveys and repeated qualitative interviews. This article presents the analyses of three cases in detail. The analytical focus was whether the factors indicated in the EV-MBC model could be used to detect significant changes in the students' educational choice processes. An important finding was that the quantitative EV-MBC surveys and the qualitative interviews gave quite different results concerning the students' considerations about the choice of tertiary education, and that significant changes in the students' reflections were not captured by the factors of the EV-MBC model. This questions the validity of the EV-MBC surveys. Moreover, the quantitative factors from the EV-MBC model did not sufficiently explain students' dynamical educational choice processes where students in parallel considered several different potential educational trajectories. We therefore call for further studies of the EV-MBC model's use in describing longitudinal choice processes and especially in investigating significant changes.

Moral intensity and climate-friendly food choices.

PubMed

Mäkiniemi, Jaana-Piia; Vainio, Annukka

2013-07-01

By changing individual food consumption patterns, it might be possible to reduce greenhouse gas emissions associated with climate change. The aim of the current study was to examine how perceptions of the moral intensity of climate change are related to climate friendly-food choices. The participants were 350 Finnish university students in the social and behavioral sciences who completed a questionnaire during class. The results indicated that moral perceptions mainly affected the moral evaluation and intentions to make climate-friendly food choices. We suggest that the results can be used to promote climate-friendly food choices, for example, by increasing the recognition of climate change as a moral imperative and by combining environmental motives with other relevant food choice motives. Copyright © 2013 Elsevier Ltd. All rights reserved.

Affective biasing of choices in gambling task decision making.

PubMed

Hinson, John M; Whitney, Paul; Holben, Heather; Wirick, Aaron K

2006-09-01

The proponents of the somatic marker hypothesis presume that rational decision making is guided by emotional reactions that are developed from prior experience. Supporting evidence for the hypothesis comes almost exclusively from the short-term affective reactions that are learned during the course of a hypothetical decision-making task--the gambling task (GT). We examined GT performance and affective reactions to choices when those choices were biased by words that had preexisting affective value. In one experiment, affectively valued words directly signaled good and bad choices. A congruent relation between affective value of word and choice outcome improved GT performance, whereas an incongruent relation greatly interfered with performance. In another experiment, affectively valued words were maintained as a working memory (WM) load between GT choices. A WM load with affectively positive words somewhat improved GT performance, whereas affectively negative words interfered with performance. Somatic markers-indicated by differential anticipatory skin conductance response (SCR) amplitude for good and bad choices-appeared at a point in the GT session when choice performance was superior. However, differential SCR developed during the session after good choice performance was already established. These results indicate that preexisting affective biases can influence GT decision making. In addition, the somatic markers that are regular accompaniments of GT decision making appeared to be temporally lagging indicators of choice performance.

Does reflection lead to wise choices?

PubMed Central

Bortolotti, Lisa

2011-01-01

Does conscious reflection lead to good decision-making? Whereas engaging in reflection is traditionally thought to be the best way to make wise choices, recent psychological evidence undermines the role of reflection in lay and expert judgement. The literature suggests that thinking about reasons does not improve the choices people make, and that experts do not engage in reflection, but base their judgements on intuition, often shaped by extensive previous experience. Can we square the traditional accounts of wisdom with the results of these empirical studies? Should we even attempt to? I shall defend the view that philosophy and cognitive sciences genuinely interact in tackling questions such as whether reflection leads to making wise choices. PMID:22408385

14 CFR § 1260.59 - Choice of law.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Choice of law. § 1260.59 Section § 1260... AGREEMENTS General Special Conditions § 1260.59 Choice of law. Choice of Law October 2000 The rights and... laws of the United States of America. However, it is understood that the laws of the Recipient's...

Making the Most of Multiple Choice

ERIC Educational Resources Information Center

Brookhart, Susan M.

2015-01-01

Multiple-choice questions draw criticism because many people perceive they test only recall or atomistic, surface-level objectives and do not require students to think. Although this can be the case, it does not have to be that way. Susan M. Brookhart suggests that multiple-choice questions are a useful part of any teacher's questioning repertoire…

Linking harvest choices to timber supply

Treesearch

Jeffrey P. Prestemon; David N. Wear

2000-01-01

Aggregate timber supply by ownership was investigated for a small region by applying stand-level harvest choice models to a representative sample of stands and then aggregating to regional totals using the area-frame of the forest survey. Timber harvest choices were estimated as probit models for three ownership categories in coastal plain southern pine stands of North...

Antecedents and Consequences of Choice.

DTIC Science & Technology

1981-04-01

ADAO97 738 VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG F/A 5/10I -A077 ANTECEDENTS AND CONSEQUENCES OF CHOICE.(U) A PR 81 L C PERIMUTER...1. REOR W ..... T ATO PAGE EAD iNSTRUCTiONS 4. TITL. , O PC OF REPORT A PERIOD COVERED( Antecedents and Consequences of Choic Final rN t 7. NTR,_C...sense of control has motivational consequences which may enhance performance on a variety of tasks .lost researchers in this field recognize that the

Choices and Consequences.

ERIC Educational Resources Information Center

Thorp, Carmany

1995-01-01

Describes student use of Hyperstudio computer software to create history adventure games. History came alive while students learned efficient writing skills; learned to understand and manipulate cause, effect choice and consequence; and learned to incorporate succinct locational, climatic, and historical detail. (ET)

Reward Contrast Effects on Impulsive Choice and Timing in Rats

PubMed Central

Smith, Aaron P.; Peterson, Jennifer R.; Kirkpatrick, Kimberly

2016-01-01

Despite considerable interest in impulsive choice as a predictor of a variety of maladaptive behaviors, the mechanisms that drive choice behavior are still poorly understood. The present study sought to examine the influence of one understudied variable, reward magnitude contrast, on choice and timing behavior as changes in magnitude commonly occur within choice procedures. In addition, assessments of indirect effects on choice behavior through magnitude-timing interactions were assessed by measuring timing within the choice task. Rats were exposed to choice procedures composed of different pairs of magnitudes of rewards for either the smaller-sooner (SS) or larger-later (LL) option. In Phase 2, the magnitude of reward either increased or decreased by 1 pellet in different groups (LL increase = 1v1→1v2; SS decrease = 2v2 → 1v2; SS increase = 1v2 → 2v2), followed by a return to baseline in Phase 3. Choice behavior was affected by the initial magnitudes experienced in the task, demonstrating a strong anchor effect. The nature of the change in magnitude affected choice behavior as well. Timing behavior was also affected by the reward contrast manipulation albeit to a lesser degree and the timing and choice effects were correlated. The results suggest that models of choice behavior should incorporate reinforcement history, reward contrast elements, and magnitude-timing interactions, but that direct effects of reward contrast on choice should be given more weight than the indirect reward-timing interactions. A better understanding of the factors that contribute to choice behavior could supply key insights into this important individual differences variable. PMID:27867839

From School Choice to Educational Choice. Education Outlook. No. 3

ERIC Educational Resources Information Center

Hess, Frederick M.; Meeks, Olivia; Manno, Bruno V.

2011-01-01

In recent decades, many calls for transformative change in American schooling have advocated school choice. Yet these calls themselves have too often accepted the orthodoxies of the nineteenth-century schoolhouse. In the new book "Customized Schooling: Beyond Whole-School Reform" (Harvard Education Press, 2011), the authors worked with the Walton…

Using a discrete choice experiment to value the QLU-C10D: feasibility and sensitivity to presentation format.

PubMed

Norman, R; Viney, R; Aaronson, N K; Brazier, J E; Cella, D; Costa, D S J; Fayers, P M; Kemmler, G; Peacock, S; Pickard, A S; Rowen, D; Street, D J; Velikova, G; Young, T A; King, M T

2016-03-01

To assess the feasibility of using a discrete choice experiment (DCE) to value health states within the QLU-C10D, a utility instrument derived from the QLQ-C30, and to assess clarity, difficulty, and respondent preference between two presentation formats. We ran a DCE valuation task in an online panel (N = 430). Respondents answered 16 choice pairs; in half of these, differences between dimensions were highlighted, and in the remainder, common dimensions were described in text and differing attributes were tabulated. To simplify the cognitive task, only four of the QLU-C10D's ten dimensions differed per choice set. We assessed difficulty and clarity of the valuation task with Likert-type scales, and respondents were asked which format they preferred. We analysed the DCE data by format with a conditional logit model and used Chi-squared tests to compare other responses by format. Semi-structured telephone interviews (N = 8) explored respondents' cognitive approaches to the valuation task. Four hundred and forty-nine individuals were recruited, 430 completed at least one choice set, and 422/449 (94 %) completed all 16 choice sets. Interviews revealed that respondents found ten domains difficult but manageable, many adopting simplifying heuristics. Results for clarity and difficulty were identical between formats, but the "highlight" format was preferred by 68 % of respondents. Conditional logit parameter estimates were monotonic within domains, suggesting respondents were able to complete the DCE sensibly, yielding valid results. A DCE valuation task in which only four of the QLU-C10D's ten dimensions differed in any choice set is feasible for deriving utility weights for the QLU-C10D.

Economic Choices Reveal Probability Distortion in Macaque Monkeys

PubMed Central

Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

2015-01-01

Economic choices are largely determined by two principal elements, reward value (utility) and probability. Although nonlinear utility functions have been acknowledged for centuries, nonlinear probability weighting (probability distortion) was only recently recognized as a ubiquitous aspect of real-world choice behavior. Even when outcome probabilities are known and acknowledged, human decision makers often overweight low probability outcomes and underweight high probability outcomes. Whereas recent studies measured utility functions and their corresponding neural correlates in monkeys, it is not known whether monkeys distort probability in a manner similar to humans. Therefore, we investigated economic choices in macaque monkeys for evidence of probability distortion. We trained two monkeys to predict reward from probabilistic gambles with constant outcome values (0.5 ml or nothing). The probability of winning was conveyed using explicit visual cues (sector stimuli). Choices between the gambles revealed that the monkeys used the explicit probability information to make meaningful decisions. Using these cues, we measured probability distortion from choices between the gambles and safe rewards. Parametric modeling of the choices revealed classic probability weighting functions with inverted-S shape. Therefore, the animals overweighted low probability rewards and underweighted high probability rewards. Empirical investigation of the behavior verified that the choices were best explained by a combination of nonlinear value and nonlinear probability distortion. Together, these results suggest that probability distortion may reflect evolutionarily preserved neuronal processing. PMID:25698750

A Review of Factors Influencing Athletes' Food Choices.

PubMed

Birkenhead, Karen L; Slater, Gary

2015-11-01

Athletes make food choices on a daily basis that can affect both health and performance. A well planned nutrition strategy that includes the careful timing and selection of appropriate foods and fluids helps to maximize training adaptations and, thus, should be an integral part of the athlete's training programme. Factors that motivate food selection include taste, convenience, nutrition knowledge and beliefs. Food choice is also influenced by physiological, social, psychological and economic factors and varies both within and between individuals and populations. This review highlights the multidimensional nature of food choice and the depth of previous research investigating eating behaviours. Despite numerous studies with general populations, little exploration has been carried out with athletes, yet the energy demands of sport typically require individuals to make more frequent and/or appropriate food choices. While factors that are important to general populations also apply to athletes, it seems likely, given the competitive demands of sport, that performance would be an important factor influencing food choice. It is unclear if athletes place the same degree of importance on these factors or how food choice is influenced by involvement in sport. There is a clear need for further research exploring the food choice motives of athletes, preferably in conjunction with research investigating dietary intake to establish if intent translates into practice.

Does health affect portfolio choice?

PubMed

Love, David A; Smith, Paul A

2010-12-01

A number of recent studies find that poor health is empirically associated with a safer portfolio allocation. It is difficult to say, however, whether this relationship is truly causal. Both health status and portfolio choice are influenced by unobserved characteristics such as risk attitudes, impatience, information, and motivation, and these unobserved factors, if not adequately controlled for, can induce significant bias in the estimates of asset demand equations. Using the 1992-2006 waves of the Health and Retirement Study, we investigate how much of the connection between health and portfolio choice is causal and how much is due to the effects of unobserved heterogeneity. Accounting for unobserved heterogeneity with fixed effects and correlated random effects models, we find that health does not appear to significantly affect portfolio choice among single households. For married households, we find a small effect (about 2-3 percentage points) from being in the lowest of five self-reported health categories. Copyright © 2009 John Wiley & Sons, Ltd.

What Sways People’s Judgment of Sleep Quality? A Quantitative Choice-Making Study With Good and Poor Sleepers

PubMed Central

Ramlee, Fatanah; Sanborn, Adam N.

2017-01-01

Abstract Study objectives: We conceptualized sleep quality judgment as a decision-making process and examined the relative importance of 17 parameters of sleep quality using a choice-based conjoint analysis. Methods: One hundred participants (50 good sleepers; 50 poor sleepers) were asked to choose between 2 written scenarios to answer 1 of 2 questions: “Which describes a better (or worse) night of sleep?”. Each scenario described a self-reported experience of sleep, stringing together 17 possible determinants of sleep quality that occur at different times of the day (day before, pre-sleep, during sleep, upon waking, day after). Each participant answered 48 questions. Logistic regression models were fit to their choice data. Results: Eleven of the 17 sleep quality parameters had a significant impact on the participants’ choices. The top 3 determinants of sleep quality were: Total sleep time, feeling refreshed (upon waking), and mood (day after). Sleep quality judgments were most influenced by factors that occur during sleep, followed by feelings and activities upon waking and the day after. There was a significant interaction between wake after sleep onset and feeling refreshed (upon waking) and between feeling refreshed (upon waking) and question type (better or worse night of sleep). Type of sleeper (good vs poor sleepers) did not significantly influence the judgments. Conclusions: Sleep quality judgments appear to be determined by not only what happened during sleep, but also what happened after the sleep period. Interventions that improve mood and functioning during the day may inadvertently also improve people’s self-reported evaluation of sleep quality. PMID:28525617

Partner Choice in Raven (Corvus corax) Cooperation.