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Sample records for posteriori parameter choice

  1. Marginal Maximum A Posteriori Item Parameter Estimation for the Generalized Graded Unfolding Model

    ERIC Educational Resources Information Center

    Roberts, James S.; Thompson, Vanessa M.

    2011-01-01

    A marginal maximum a posteriori (MMAP) procedure was implemented to estimate item parameters in the generalized graded unfolding model (GGUM). Estimates from the MMAP method were compared with those derived from marginal maximum likelihood (MML) and Markov chain Monte Carlo (MCMC) procedures in a recovery simulation that varied sample size,…

  2. Parameter Choices for Approximation by Harmonic Splines

    NASA Astrophysics Data System (ADS)

    Gutting, Martin

    2016-04-01

    The approximation by harmonic trial functions allows the construction of the solution of boundary value problems in geoscience, e.g., in terms of harmonic splines. Due to their localizing properties regional modeling or the improvement of a global model in a part of the Earth's surface is possible with splines. Fast multipole methods have been developed for some cases of the occurring kernels to obtain a fast matrix-vector multiplication. The main idea of the fast multipole algorithm consists of a hierarchical decomposition of the computational domain into cubes and a kernel approximation for the more distant points. This reduces the numerical effort of the matrix-vector multiplication from quadratic to linear in reference to the number of points for a prescribed accuracy of the kernel approximation. The application of the fast multipole method to spline approximation which also allows the treatment of noisy data requires the choice of a smoothing parameter. We investigate different methods to (ideally automatically) choose this parameter with and without prior knowledge of the noise level. Thereby, the performance of these methods is considered for different types of noise in a large simulation study. Applications to gravitational field modeling are presented as well as the extension to boundary value problems where the boundary is the known surface of the Earth itself.

  3. On the choice of parameters in solar-structure inversion

    NASA Astrophysics Data System (ADS)

    Rabello-Soares, M. C.; Basu, Sarbani; Christensen-Dalsgaard, J.

    1999-10-01

    The observed solar p-mode frequencies provide a powerful diagnostic of the internal structure of the Sun and permit us to test in considerable detail the physics used in the theory of stellar structure. Among the most commonly used techniques for inverting such helioseismic data are two implementations of the optimally localized averages (OLA) method, namely the subtractive optimally localized averages (SOLA) and multiplicative optimally localized averages (MOLA). Both are controlled by a number of parameters, the proper choice of which is very important for a reliable inference of the solar internal structure. Here we make a detailed analysis of the influence of each parameter on the solution and indicate how to arrive at an optimal set of parameters for a given data set.

  4. An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography

    SciTech Connect

    Feng Jinchao; Qin Chenghu; Jia Kebin; Han Dong; Liu Kai; Zhu Shouping; Yang Xin; Tian Jie

    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 bioluminescent 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 were used

  5. Cognitive models of risky choice: parameter stability and predictive accuracy of prospect theory.

    PubMed

    Glöckner, Andreas; Pachur, Thorsten

    2012-04-01

    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 individual differences as measured by model parameters stable enough to improve the ability to predict behavior as compared to modeling without adjustable parameters? We examined this issue in cumulative prospect theory (CPT), arguably the most widely used framework to model decisions under risk. Specifically, we examined (a) the temporal stability of CPT's parameters; and (b) how well different implementations of CPT, varying in the number of adjustable parameters, predict individual choice relative to models with no adjustable parameters (such as CPT with fixed parameters, expected value theory, and various heuristics). We presented participants with risky choice problems and fitted CPT to each individual's choices in two separate sessions (which were 1 week apart). All parameters were correlated across time, in particular when using a simple implementation of CPT. CPT allowing for individual variability in parameter values predicted individual choice better than CPT with fixed parameters, expected value theory, and the heuristics. CPT's parameters thus seem to pick up stable individual differences that need to be considered when predicting risky choice.

  6. Specifics of Mode Parameters Choice Under Twin Arc Welding of Fillet Welds

    NASA Astrophysics Data System (ADS)

    Melnikov, A. U.; Fiveyskiy, A. M.; Sholokhov, M. A.

    2016-04-01

    The present article covers the specifics of mode parameters choice under twin arc welding of fillet welds. The necessity of mode parameters adjustment at the second arc due to heated metal of the first arc was proven. The obtained correction indexes allow us to determine with satisfactory accuracy the mode parameters under given dimensions of weld joint.

  7. 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.

  8. 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. PMID:18802123

  9. Method study of parameter choice for a circular proton-proton collider

    NASA Astrophysics Data System (ADS)

    Su, Feng; Gao, Jie; Xiao, Ming; Wang, Dou; Wang, Yi-Wei; Bai, Sha; Bian, Tian-Jian

    2016-01-01

    In this paper we show a systematic method of appropriate parameter choice for a circular proton-proton collider by using an analytical expression for the beam-beam tune shift limit, starting from a given design goal and technical limitations. A suitable parameter space has been explored. Based on the parameter scan, sets of appropriate parameters designed for a 50 km and 100 km circular proton-proton collider are proposed. Supported by National Natural Science Foundation of China (11175192)

  10. Empirical estimation of consistency parameter in intertemporal choice based on Tsallis’ statistics

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

    Impulsivity and inconsistency in intertemporal choice have been attracting attention in econophysics and neuroeconomics. Although loss of self-control by substance abusers is strongly related to their inconsistency in intertemporal choice, researchers in neuroeconomics and psychopharmacology have usually studied impulsivity in intertemporal choice using a discount rate (e.g. hyperbolic k), with little effort being expended on parameterizing subject's inconsistency in intertemporal choice. Recent studies using Tsallis’ statistics-based econophysics have found a discount function (i.e. q-exponential discount function), which may continuously parameterize a subject's consistency in intertemporal choice. In order to examine the usefulness of the consistency parameter (0⩽q⩽1) in the q-exponential discounting function in behavioral studies, we experimentally estimated the consistency parameter q in Tsallis’ statistics-based discounting function by assessing the points of subjective equality (indifference points) at seven delays (1 week-25 years) in humans (N=24). We observed that most (N=19) subjects’ intertemporal choice was completely inconsistent ( q=0, i.e. hyperbolic discounting), the mean consistency (0⩽q⩽1) was smaller than 0.5, and only one subject had a completely consistent intertemporal choice ( q=1, i.e. exponential discounting). There was no significant correlation between impulsivity and inconsistency parameters. Our results indicate that individual differences in consistency in intertemporal choice can be parameterized by introducing a q-exponential discount function and most people discount delayed rewards hyperbolically, rather than exponentially (i.e. mean q is smaller than 0.5). Further, impulsivity and inconsistency in intertemporal choice can be considered as separate behavioral tendencies. The usefulness of the consistency parameter q in psychopharmacological studies of addictive behavior was demonstrated in the present study.

  11. 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

  12. Influence of choice of null network on small-world parameters of structural correlation networks.

    PubMed

    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.

  13. A posteriori error control in numerical simulations of semiconductor nanodevices

    NASA Astrophysics Data System (ADS)

    Chen, Ren-Chuen; Li, Chun-Hsien; Liu, Jinn-Liang

    2016-10-01

    A posteriori error estimation and control methods are proposed for a quantum corrected energy balance (QCEB) model that describes electron and hole flows in semiconductor nanodevices under the influence of electrical, diffusive, thermal, and quantum effects. The error estimation is based on the maximum norm a posteriori error estimate developed by Kopteva (2008) for singularly perturbed semilinear reaction-diffusion problems. The error estimate results in three error estimators called the first-, second-, and third-order estimators to guide the refinement process. The second-order estimator is shown to be most effective for adaptive mesh refinement. The QCEB model is scaled to a dimensionless coupled system of seven singularly perturbed semilinear PDEs with various perturbation parameters so that the estimator can be applied to each PDE on equal footing. It is found that the estimator suitable for controlling the approximation error of one PDE (one physical variable) may not be suitable for another PDE, indicating that different parameters account for different boundary or interior layer regions as illustrated by two different semiconductor devices, namely, a diode and a MOSFET. A hybrid approach to automatically choosing different PDEs for calculating the estimator in the adaptive mesh refinement process is shown to be able to control the errors of all PDEs uniformly.

  14. [ETHICAL PRINCIPALS AND A POSTERIORI JUSTIFICATIONS].

    PubMed

    Heintz, Monica

    2015-12-01

    It is difficult to conceive that the human being, while being the same everywhere, could be cared for in such different ways in other societies. Anthropologists acknowledge that the diversity of cultures implies a diversity of moral values, thus that in a multicultural society the individual could draw upon different moral frames to justify the peculiarities of her/his demand of care. But how could we determine what is the moral frame that catalyzes behaviour while all we can record are a posteriori justifications of actions? In most multicultural societies where several moralframes coexist, there is an implicit hierarchy between ethical systems derived from a hierarchy of power which falsifies these a posteriori justifications. Moreover anthropologists often fail to acknowledge that individual behaviour does not always reflect individual values, but is more often the result of negotiations between the moralframes available in society and her/his own desires and personal experience. This is certainly due to the difficulty to account for a dynamic and complex interplay of moral values that cannot be analysed as a system. The impact of individual experience on the way individuals give or receive care could also be only weakly linked to a moral system even when this reference comes up explicitly in the a posteriori justifications. PMID:27120823

  15. 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.

  16. On the choice of GARCH parameters for efficient modelling of real stock price dynamics

    NASA Astrophysics Data System (ADS)

    Pokhilchuk, K. A.; Savel'ev, S. E.

    2016-04-01

    We propose two different methods for optimal choice of GARCH(1,1) parameters for the efficient modelling of stock prices by using a particular return series. Using (as an example) stock return data for Intel Corporation, we vary parameters to fit the average volatility as well as fourth (linked to kurtosis of data) and eighth statistical moments and observe pure convergence of our simulated eighth moment to the stock data. Results indicate that fitting higher-order moments of a return series might not be an optimal approach for choosing GARCH parameters. In contrast, the simulated exponent of the Fourier spectrum decay is much less noisy and can easily fit the corresponding decay of the empirical Fourier spectrum of the used return series of Intel stock, allowing us to efficiently define all GARCH parameters. We compare the estimates of GARCH parameters obtained by fitting price data Fourier spectra with the ones obtained from standard software packages and conclude that the obtained estimates here are deeper in the stability region of parameters. Thus, the proposed method of using Fourier spectra of stock data to estimate GARCH parameters results in a more robust and stable stochastic process but with a shorter characteristic autocovariance time.

  17. An Anisotropic A posteriori Error Estimator for CFD

    NASA Astrophysics Data System (ADS)

    Feijóo, Raúl A.; Padra, Claudio; Quintana, Fernando

    In this article, a robust anisotropic adaptive algorithm is presented, to solve compressible-flow equations using a stabilized CFD solver and automatic mesh generators. The association includes a mesh generator, a flow solver, and an a posteriori error-estimator code. The estimator was selected among several choices available (Almeida et al. (2000). Comput. Methods Appl. Mech. Engng, 182, 379-400; Borges et al. (1998). "Computational mechanics: new trends and applications". Proceedings of the 4th World Congress on Computational Mechanics, Bs.As., Argentina) giving a powerful computational tool. The main aim is to capture solution discontinuities, in this case, shocks, using the least amount of computational resources, i.e. elements, compatible with a solution of good quality. This leads to high aspect-ratio elements (stretching). To achieve this, a directional error estimator was specifically selected. The numerical results show good behavior of the error estimator, resulting in strongly-adapted meshes in few steps, typically three or four iterations, enough to capture shocks using a moderate and well-distributed amount of elements.

  18. Robust contrast source inversion method with automatic choice rule of regularization parameters for ultrasound waveform tomography

    NASA Astrophysics Data System (ADS)

    Lin, Hongxiang; Azuma, Takashi; Qu, Xiaolei; Takagi, Shu

    2016-07-01

    We consider ultrasound waveform tomography using an ultrasound prototype equipped with the ring-array transducers. For this purpose, we use robust contrast source inversion (robust CSI), viz extended contrast source inversion, to reconstruct the sound-speed image from the wave-field data. The robust CSI method is implemented by the alternating minimization method. An automatic choice rule is employed into the alternating minimization method in order to heuristically determine a suitable regularization parameter while iterating. We prove the convergence of this algorithm. The numerical examples show that the robust CSI method with the automatic choice rule improves the spatial resolution of medical images and enhances the robustness, even when the wave-field data of a wavelength of 6.16 mm contaminated by 5% noise are used. The numerical results also show that the images reconstructed by the proposed method yield a spatial resolution of approximately half the wavelength that may be adequate for imaging a breast tumor at Stage I.

  19. Electron transport in magnetrons by a posteriori Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Costin, C.; Minea, T. M.; Popa, G.

    2014-02-01

    Electron transport across magnetic barriers is crucial in all magnetized plasmas. It governs not only the plasma parameters in the volume, but also the fluxes of charged particles towards the electrodes and walls. It is particularly important in high-power impulse magnetron sputtering (HiPIMS) reactors, influencing the quality of the deposited thin films, since this type of discharge is characterized by an increased ionization fraction of the sputtered material. Transport coefficients of electron clouds released both from the cathode and from several locations in the discharge volume are calculated for a HiPIMS discharge with pre-ionization operated in argon at 0.67 Pa and for very short pulses (few µs) using the a posteriori Monte Carlo simulation technique. For this type of discharge electron transport is characterized by strong temporal and spatial dependence. Both drift velocity and diffusion coefficient depend on the releasing position of the electron cloud. They exhibit minimum values at the centre of the race-track for the secondary electrons released from the cathode. The diffusion coefficient of the same electrons increases from 2 to 4 times when the cathode voltage is doubled, in the first 1.5 µs of the pulse. These parameters are discussed with respect to empirical Bohm diffusion.

  20. Parameters of rewards on choice behavior in Siamese fighting fish (Betta splendens).

    PubMed

    Shapiro, Martin S; Jensen, Ashley L

    2009-09-01

    Five experiments were conducted with Siamese fighting fish (Betta splendens) to investigate how choices in a T-maze were affected by parameters of a social reward (aggression display to another male): presence or absence, amount, delay and distance traveled. Bettas showed a preference for the side associated with the presence of another male rather than the side associated with nothing (Exp 1), a greater length of time of the reward (Exp 2) and shorter delay (Exp 3). The animals were indifferent when one side offered a longer delay to a longer reward time compared with a shorter delay to a shorter reward time (Exp 4). What was most surprising, however, was that fish preferred to choose the side that was associated with swimming a greater distance to reach an opponent male (Exp 5). These experiments demonstrate that, while some parameters of a visual reward affect behavior in predictable ways (greater amount, shorter delay), the complex motivations underlying inter-male aggression can produce what appear to be paradoxical results.

  1. Parameters of rewards on choice behavior in Siamese fighting fish (Betta splendens).

    PubMed

    Shapiro, Martin S; Jensen, Ashley L

    2009-09-01

    Five experiments were conducted with Siamese fighting fish (Betta splendens) to investigate how choices in a T-maze were affected by parameters of a social reward (aggression display to another male): presence or absence, amount, delay and distance traveled. Bettas showed a preference for the side associated with the presence of another male rather than the side associated with nothing (Exp 1), a greater length of time of the reward (Exp 2) and shorter delay (Exp 3). The animals were indifferent when one side offered a longer delay to a longer reward time compared with a shorter delay to a shorter reward time (Exp 4). What was most surprising, however, was that fish preferred to choose the side that was associated with swimming a greater distance to reach an opponent male (Exp 5). These experiments demonstrate that, while some parameters of a visual reward affect behavior in predictable ways (greater amount, shorter delay), the complex motivations underlying inter-male aggression can produce what appear to be paradoxical results. PMID:19615613

  2. Superconvergence and recovery type a posteriori error estimation for hybrid stress finite element method

    NASA Astrophysics Data System (ADS)

    Bai, YanHong; Wu, YongKe; Xie, XiaoPing

    2016-09-01

    Superconvergence and a posteriori error estimators of recovery type are analyzed for the 4-node hybrid stress quadrilateral finite element method proposed by Pian and Sumihara (Int. J. Numer. Meth. Engrg., 1984, 20: 1685-1695) for linear elasticity problems. Uniform superconvergence of order $O(h^{1+\\min\\{\\alpha,1\\}})$ with respect to the Lam\\'{e} constant $\\lambda$ is established for both the recovered gradients of the displacement vector and the stress tensor under a mesh assumption, where $\\alpha>0$ is a parameter characterizing the distortion of meshes from parallelograms to quadrilaterals. A posteriori error estimators based on the recovered quantities are shown to be asymptotically exact. Numerical experiments confirm the theoretical results.

  3. 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.

  4. A Posteriori Analysis for Hydrodynamic Simulations Using Adjoint Methodologies

    SciTech Connect

    Woodward, C S; Estep, D; Sandelin, J; Wang, H

    2009-02-26

    This report contains results of analysis done during an FY08 feasibility study investigating the use of adjoint methodologies for a posteriori error estimation for hydrodynamics simulations. We developed an approach to adjoint analysis for these systems through use of modified equations and viscosity solutions. Targeting first the 1D Burgers equation, we include a verification of the adjoint operator for the modified equation for the Lax-Friedrichs scheme, then derivations of an a posteriori error analysis for a finite difference scheme and a discontinuous Galerkin scheme applied to this problem. We include some numerical results showing the use of the error estimate. Lastly, we develop a computable a posteriori error estimate for the MAC scheme applied to stationary Navier-Stokes.

  5. 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

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

    PubMed

    Wang, Yong; Ma, Xiaolei; Liu, Yong; Gong, Ke; Henrickson, Kristian C; 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

  7. Mean phase predictor for maximum a posteriori demodulator

    NASA Technical Reports Server (NTRS)

    Altes, Richard A. (Inventor)

    1996-01-01

    A system and method for optimal maximum a posteriori (MAP) demodulation using a novel mean phase predictor. The mean phase predictor conducts cumulative averaging over multiple blocks of phase samples to provide accurate prior mean phases, to be input into a MAP phase estimator.

  8. 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…

  9. A posteriori error covariances in variational data assimilation

    NASA Astrophysics Data System (ADS)

    Shutyaev, V.; Le Dimet, F.-X.; Gejadze, I.

    2009-04-01

    The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to find unknown model parameters such as initial and/or boundary conditions, right-hand sides (forcing), and distributed coefficients. A necessary optimality condition reduces the problem to the optimality system (see, e.g.[1]) which includes input errors (background and observation errors); hence the error in the optimal solution. The error in the optimal solution can be derived through the errors in the input data using the Hessian of the cost functional of an auxiliary data assimilation problem. For a deterministic case it was done in [2]. In [3], a similar result was obtained for the continuous operator formulation, where a nonlinear evolution problem with an unknown initial condition was considered, with random errors in the input data subjected to the normal distribution. Here we present an extension of the results reported in [3] for the case of other model parameters (boundary conditions, coefficients, etc.) and show that in a nonlinear case the a posteriori covariance operator of the optimal solution error can be approximated by the inverse Hessian of the auxiliary data assimilation problem based on the tangent linear model constraints. We also demonstrate that this approximation could be sufficiently accurate even though the tangent linear hypotheses is not valid. Numerical examples are presented for a nonlinear convection-diffusion problem. This work was carried out within the MOISE project (CNRS, INRIA, UJF, INPG), ADAMS project and the project 06-01-00344 of the Russian Foundation for the Basic Research and within the programme ECO-NET (EGIDE). References: 1. Le Dimet F.X., Talagrand O. Variational algorithms for analysis and assimilation of meteorological observations: theoretical aspects. Tellus, 1986, v.38A, pp.97-110. 2. Le Dimet F.-X., Shutyaev V. On deterministic error analysis in variational data assimilation. Nonlinear

  10. Maximum a posteriori resampling of noisy, spatially correlated data

    NASA Astrophysics Data System (ADS)

    Goff, John A.; Jenkins, Chris; Calder, Brian

    2006-08-01

    In any geologic application, noisy data are sources of consternation for researchers, inhibiting interpretability and marring images with unsightly and unrealistic artifacts. Filtering is the typical solution to dealing with noisy data. However, filtering commonly suffers from ad hoc (i.e., uncalibrated, ungoverned) application. We present here an alternative to filtering: a newly developed method for correcting noise in data by finding the "best" value given available information. The motivating rationale is that data points that are close to each other in space cannot differ by "too much," where "too much" is governed by the field covariance. Data with large uncertainties will frequently violate this condition and therefore ought to be corrected, or "resampled." Our solution for resampling is determined by the maximum of the a posteriori density function defined by the intersection of (1) the data error probability density function (pdf) and (2) the conditional pdf, determined by the geostatistical kriging algorithm applied to proximal data values. A maximum a posteriori solution can be computed sequentially going through all the data, but the solution depends on the order in which the data are examined. We approximate the global a posteriori solution by randomizing this order and taking the average. A test with a synthetic data set sampled from a known field demonstrates quantitatively and qualitatively the improvement provided by the maximum a posteriori resampling algorithm. The method is also applied to three marine geology/geophysics data examples, demonstrating the viability of the method for diverse applications: (1) three generations of bathymetric data on the New Jersey shelf with disparate data uncertainties; (2) mean grain size data from the Adriatic Sea, which is a combination of both analytic (low uncertainty) and word-based (higher uncertainty) sources; and (3) side-scan backscatter data from the Martha's Vineyard Coastal Observatory which are, as

  11. Suitable parameter choice on quantitative morphology of A549 cell in epithelial–mesenchymal transition

    PubMed Central

    Ren, Zhou-Xin; Yu, Hai-Bin; Li, Jian-Sheng; Shen, Jun-Ling; Du, Wen-Sen

    2015-01-01

    Evaluation of morphological changes in cells is an integral part of study on epithelial to mesenchymal transition (EMT), however, only a few papers reported the changes in quantitative parameters and no article compared different parameters for demanding better parameters. In the study, the purpose was to investigate suitable parameters for quantitative evaluation of EMT morphological changes. A549 human lung adenocarcinoma cell line was selected for the study. Some cells were stimulated by transforming growth factor-β1 (TGF-β1) for EMT, and other cells were as control without TGF-β1 stimulation. Subsequently, cells were placed in phase contrast microscope and three arbitrary fields were captured and saved with a personal computer. Using the tools of Photoshop software, some cells in an image were selected, segmented out and exchanged into unique hue, and other part in the image was shifted into another unique hue. The cells were calculated with 29 morphological parameters by Image Pro Plus software. A parameter between cells with or without TGF-β1 stimulation was compared statistically and nine parameters were significantly different between them. Receiver operating characteristic curve (ROC curve) of a parameter was described with SPSS software and F-test was used to compare two areas under the curves (AUCs) in Excel. Among them, roundness and radius ratio were the most AUCs and were significant higher than the other parameters. The results provided a new method with quantitative assessment of cell morphology during EMT, and found out two parameters, roundness and radius ratio, as suitable for quantification. PMID:26182364

  12. Sensitivity of Human Choice to Manipulations of Parameters of Positive and Negative Sound Reinforcement

    ERIC Educational Resources Information Center

    Lambert, Joseph M.

    2013-01-01

    The purpose of this study was to determine whether altering parameters of positive and negative reinforcement in identical ways could influence behavior maintained by each in different ways. Three undergraduate students participated in a series of assessments designed to identify preferred and aversive sounds with similar reinforcing values.…

  13. 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…

  14. Comparing species decisions in a dichotomous choice task: adjusting task parameters improves performance in monkeys.

    PubMed

    Prétôt, Laurent; Bshary, Redouan; Brosnan, Sarah F

    2016-07-01

    In comparative psychology, both similarities and differences among species are studied to better understand the evolution of their behavior. To do so, we first test species in tasks using similar procedures, but if differences are found, it is important to determine their underlying cause(s) (e.g., are they due to ecology, cognitive ability, an artifact of the study, and/or some other factor?). In our previous work, primates performed unexpectedly poorly on an apparently simple two-choice discrimination task based on the natural behavior of cleaner fish, while the fish did quite well. In this task, if the subjects first chose one of the options (ephemeral) they received both food items, but if they chose the other (permanent) option first, the ephemeral option disappeared. Here, we test several proposed explanations for primates' relatively poorer performance. In Study 1, we used a computerized paradigm that differed from the previous test by removing interaction with human experimenters, which may be distracting, and providing a more standardized testing environment. In Study 2, we adapted the computerized paradigm from Study 1 to be more relevant to primate ecology. Monkeys' overall performance in these adapted tasks matched the performance of the fish in the original study, showing that with the appropriate modifications they can solve the task. We discuss these results in light of comparative research, which requires balancing procedural similarity with considerations of how the details of the task or the context may influence how different species perceive and solve tasks differently. PMID:27086302

  15. A unified approach for a posteriori high-order curved mesh generation using solid mechanics

    NASA Astrophysics Data System (ADS)

    Poya, Roman; Sevilla, Ruben; Gil, Antonio J.

    2016-09-01

    The paper presents a unified approach for the a posteriori generation of arbitrary high-order curvilinear meshes via a solid mechanics analogy. The approach encompasses a variety of methodologies, ranging from the popular incremental linear elastic approach to very sophisticated non-linear elasticity. In addition, an intermediate consistent incrementally linearised approach is also presented and applied for the first time in this context. Utilising a consistent derivation from energy principles, a theoretical comparison of the various approaches is presented which enables a detailed discussion regarding the material characterisation (calibration) employed for the different solid mechanics formulations. Five independent quality measures are proposed and their relations with existing quality indicators, used in the context of a posteriori mesh generation, are discussed. Finally, a comprehensive range of numerical examples, both in two and three dimensions, including challenging geometries of interest to the solids, fluids and electromagnetics communities, are shown in order to illustrate and thoroughly compare the performance of the different methodologies. This comparison considers the influence of material parameters and number of load increments on the quality of the generated high-order mesh, overall computational cost and, crucially, the approximation properties of the resulting mesh when considering an isoparametric finite element formulation.

  16. Parameter Choice and Constraint in Hydrologic Models for Evaluating Land Use Change

    NASA Astrophysics Data System (ADS)

    Jackson, C. R.

    2011-12-01

    Hydrologic models are used to answer questions, from simple, "what is the expected 100-year peak flow for a basin?", to complex, "how will land use change alter flow pathways, flow time series, and water chemistry?" Appropriate model structure and complexity depend on the questions being addressed. Numerous studies of simple transfer models for converting climate signals into streamflows suggest that only three or four parameters are needed. The conceptual corollary to such models is a single hillslope bucket with storage, evapotranspiration, fast flow, and slow flow. While having the benefit of low uncertainty, such models are ill-suited to addressing land use questions. Land use questions require models that can simulate effects of changes in vegetation, alterations of soil characteristics, and resulting changes in flow pathways. For example, minimum goals for a hydrologic model evaluating bioenergy feedstock production might include: 1) calculate Horton overland flow based on surface conductivities and saturated surface flow based on relative moisture content in the topsoils, 2) allow reinfiltration of Horton overland flow created by bare soils, compacted soils, and pavement (roads, logging roads, skid trails, landings), 3) account for root zone depth and LAI in transpiration calculations, 4) allow mixing of hillslope flows in the riparian aquifer, 5) allow separate simulation of the riparian soils and vegetation and upslope soils and vegetation, 6) incorporate important aspects of topography and stratigraphy, and 7) estimate residence times in different flow paths. How many parameters are needed for such a model, and what information beside streamflow can be collected to constrain the parameters? Additional information that can be used for evaluating and testing watershed models are in-situ conductivity measurements, soil porosity, soil moisture dynamics, shallow perched groundwater behavior, interflow occurrence, groundwater behavior, regional ET estimates

  17. How Sensitive are Helioseismic Mode Parameters and Subsurface Flows to Choice of the Spectral Line?

    NASA Astrophysics Data System (ADS)

    Hill, Frank; Jain, K.; Gonzalez-Hernandez, I.; Toner, C. G.; Tripathy, S. C.; Armstrong, J. D.; Jefferies, S.; Rhodes, E. J., Jr.; Rose, P. J.

    2006-06-01

    We analyze simultaneous multi-spectral line observations to investigate how the results of helioseismology are affected by the spectral line used to observe the solar oscillations. The data sets include observations obtained with the Ni I 676.8 nm (from Global Oscillation Network Group - GONG), K I 769.9 nm (from Magneto Optical Filters at Two Heights - MOTH experiment) and Na I D2 589.0 nm (from MOTH experiment and Mount Wilson Observatory) lines during the Austral summer of 2002-03. The depth formation of these lines occurs about 200 km, 420 km and 780 km above the base of the photosphere, respectively. The simultaneous observations in several atmospheric layers allow us to determine the propagation behavior of acoustic waves between these layers. We carry out ring-diagram analysis, a local helioseismology technique, to study the relative changes in local mode parameters and subsurface velocity fields inferred from the different data sets. Preliminary analysis of the mode parameters obtained from the Ni I 676.8 nm and K I 769.9 nm spectral lines clearly show a significant increase in mode amplitude with increasing observing height but with no apparent change in the mode width.

  18. Parameter choices for a muon recirculating linear accelerator from 5 to 63 GeV

    SciTech Connect

    Berg, J. S.

    2014-06-19

    A recirculating linear accelerator (RLA) has been proposed to accelerate muons from 5 to 63 GeV for a muon collider. It should be usable both for a Higgs factory and as a stage for a higher energy collider. First, the constraints due to the beam loading are computed. Next, an expression for the longitudinal emittance growth to lowest order in the longitudinal emittance is worked out. After finding the longitudinal expression, a simplified model that describes the arcs and their approximate expression for the time of flight dependence on energy in those arcs is found. Finally, these results are used to estimate the parameters required for the RLA arcs and the linac phase.

  19. STECKMAP: STEllar Content and Kinematics via Maximum A Posteriori likelihood

    NASA Astrophysics Data System (ADS)

    Ocvirk, P.

    2011-08-01

    STECKMAP stands for STEllar Content and Kinematics via Maximum A Posteriori likelihood. It is a tool for interpreting galaxy spectra in terms of their stellar populations through the derivation of their star formation history, age-metallicity relation, kinematics and extinction. The observed spectrum is projected onto a temporal sequence of models of single stellar populations, so as to determine a linear combination of these models that best fits the observed spectrum. The weights of the various components of this linear combination indicate the stellar content of the population. This procedure is regularized using various penalizing functions. The principles of the method are detailed in Ocvirk et al. 2006.

  20. 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.

  1. High speed e-beam writing for large area photonic nanostructures — a choice of parameters

    NASA Astrophysics Data System (ADS)

    Li, Kezheng; Li, Juntao; Reardon, Christopher; Schuster, Christian S.; Wang, Yue; Triggs, Graham J.; Damnik, Niklas; Müenchenberger, Jana; Wang, Xuehua; Martins, Emiliano R.; Krauss, Thomas F.

    2016-09-01

    Photonic nanostructures are used for many optical systems and applications. However, some high-end applications require the use of electron-beam lithography (EBL) to generate such nanostructures. An important technological bottleneck is the exposure time of the EBL systems, which can exceed 24 hours per 1 cm2. Here, we have developed a method based on a target function to systematically increase the writing speed of EBL. As an example, we use as the target function the fidelity of the Fourier Transform spectra of nanostructures that are designed for thin film light trapping applications, and optimize the full parameter space of the lithography process. Finally, we are able to reduce the exposure time by a factor of 5.5 without loss of photonic performance. We show that the performances of the fastest written structures are identical to the original ones within experimental error. As the target function can be varied according to different purposes, the method is also applicable to guided mode resonant grating and many other areas. These findings contribute to the advancement of EBL and point towards making the technology more attractive for commercial applications.

  2. High speed e-beam writing for large area photonic nanostructures — a choice of parameters

    PubMed Central

    Li, Kezheng; Li, Juntao; Reardon, Christopher; Schuster, Christian S.; Wang, Yue; Triggs, Graham J.; Damnik, Niklas; Müenchenberger, Jana; Wang, Xuehua; Martins, Emiliano R.; Krauss, Thomas F.

    2016-01-01

    Photonic nanostructures are used for many optical systems and applications. However, some high-end applications require the use of electron-beam lithography (EBL) to generate such nanostructures. An important technological bottleneck is the exposure time of the EBL systems, which can exceed 24 hours per 1 cm2. Here, we have developed a method based on a target function to systematically increase the writing speed of EBL. As an example, we use as the target function the fidelity of the Fourier Transform spectra of nanostructures that are designed for thin film light trapping applications, and optimize the full parameter space of the lithography process. Finally, we are able to reduce the exposure time by a factor of 5.5 without loss of photonic performance. We show that the performances of the fastest written structures are identical to the original ones within experimental error. As the target function can be varied according to different purposes, the method is also applicable to guided mode resonant grating and many other areas. These findings contribute to the advancement of EBL and point towards making the technology more attractive for commercial applications. PMID:27633902

  3. High speed e-beam writing for large area photonic nanostructures - a choice of parameters.

    PubMed

    Li, Kezheng; Li, Juntao; Reardon, Christopher; Schuster, Christian S; Wang, Yue; Triggs, Graham J; Damnik, Niklas; Müenchenberger, Jana; Wang, Xuehua; Martins, Emiliano R; Krauss, Thomas F

    2016-09-16

    Photonic nanostructures are used for many optical systems and applications. However, some high-end applications require the use of electron-beam lithography (EBL) to generate such nanostructures. An important technological bottleneck is the exposure time of the EBL systems, which can exceed 24 hours per 1 cm(2). Here, we have developed a method based on a target function to systematically increase the writing speed of EBL. As an example, we use as the target function the fidelity of the Fourier Transform spectra of nanostructures that are designed for thin film light trapping applications, and optimize the full parameter space of the lithography process. Finally, we are able to reduce the exposure time by a factor of 5.5 without loss of photonic performance. We show that the performances of the fastest written structures are identical to the original ones within experimental error. As the target function can be varied according to different purposes, the method is also applicable to guided mode resonant grating and many other areas. These findings contribute to the advancement of EBL and point towards making the technology more attractive for commercial applications.

  4. High speed e-beam writing for large area photonic nanostructures - a choice of parameters.

    PubMed

    Li, Kezheng; Li, Juntao; Reardon, Christopher; Schuster, Christian S; Wang, Yue; Triggs, Graham J; Damnik, Niklas; Müenchenberger, Jana; Wang, Xuehua; Martins, Emiliano R; Krauss, Thomas F

    2016-01-01

    Photonic nanostructures are used for many optical systems and applications. However, some high-end applications require the use of electron-beam lithography (EBL) to generate such nanostructures. An important technological bottleneck is the exposure time of the EBL systems, which can exceed 24 hours per 1 cm(2). Here, we have developed a method based on a target function to systematically increase the writing speed of EBL. As an example, we use as the target function the fidelity of the Fourier Transform spectra of nanostructures that are designed for thin film light trapping applications, and optimize the full parameter space of the lithography process. Finally, we are able to reduce the exposure time by a factor of 5.5 without loss of photonic performance. We show that the performances of the fastest written structures are identical to the original ones within experimental error. As the target function can be varied according to different purposes, the method is also applicable to guided mode resonant grating and many other areas. These findings contribute to the advancement of EBL and point towards making the technology more attractive for commercial applications. PMID:27633902

  5. Effects of using a posteriori methods for the conservation of integral invariants. [for weather forecasting

    NASA Technical Reports Server (NTRS)

    Takacs, Lawrence L.

    1988-01-01

    The nature and effect of using a posteriori adjustments to nonconservative finite-difference schemes to enforce integral invariants of the corresponding analytic system are examined. The method of a posteriori integral constraint restoration is analyzed for the case of linear advection, and the harmonic response associated with the a posteriori adjustments is examined in detail. The conservative properties of the shallow water system are reviewed, and the constraint restoration algorithm applied to the shallow water equations are described. A comparison is made between forecasts obtained using implicit and a posteriori methods for the conservation of mass, energy, and potential enstrophy in the complete nonlinear shallow-water system.

  6. Discrete dipole approximation simulations of gold nanorod optical properties: Choice of input parameters and comparison with experiment

    NASA Astrophysics Data System (ADS)

    Ungureanu, Constantin; Rayavarapu, Raja Gopal; Manohar, Srirang; van Leeuwen, Ton G.

    2009-05-01

    Gold nanorods have interesting optical properties due to surface plasmon resonance effects. A variety of biomedical applications of these particles have been envisaged and feasibilities demonstrated in imaging, sensing, and therapy based on the interactions of light with these particles. In order to correctly interpret experimental data and tailor the nanorods and their environments for optimal use in these applications, simulations of the optical properties of the particles under various conditions are essential. Of various numerical methods available, the discrete dipole approximation (DDA) approach implemented in the publicly available DDSCAT code is a powerful method that had proved popular for studying gold nanorods. However, there is as yet no universal agreement on the shape used to represent the nanorods and on the dielectric function of gold required for the simulations. We systematically study the influence of these parameters on simulated results. We find large variations in the position of plasmon resonance peaks, their amplitudes, and shapes of the spectra depending on the choice of the parameters. We discuss these in the light of experimental optical extinction spectra of gold nanorods synthesized in our laboratory. We show that much care should be taken and prudence applied before DDA results be used to interpret experimental data and to help characterize nanoparticles synthesized.

  7. Testing the role of the Barbero-Immirzi parameter and the choice of connection in loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Achour, Jibril Ben; Geiller, Marc; Noui, Karim; Yu, Chao

    2015-05-01

    We study the role of the Barbero-Immirzi parameter γ and the choice of connection in the construction of (a symmetry-reduced version of) loop quantum gravity. We start with the four-dimensional Lorentzian Holst action that we reduce to three dimensions in a way that preserves the presence of γ . In the time gauge, the phase space of the resulting three-dimensional theory mimics exactly that of the four-dimensional one. Its quantization can be performed, and on the kinematical Hilbert space spanned by SU(2) spin network states the spectra of geometric operators are discrete and γ dependent. However, because of the three-dimensional nature of the theory, its SU(2) Ashtekar-Barbero Hamiltonian constraint can be traded for the flatness constraint of an s l (2 ,C ) connection, and we show that this latter has to satisfy a linear simplicitylike condition analogous to the one used in the construction of spin foam models. The physically relevant solution to this constraint singles out the noncompact subgroup SU(1, 1), which in turn leads to the disappearance of the Barbero-Immirzi parameter and to a continuous length spectrum, in agreement with what is expected from Lorentzian three-dimensional gravity.

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

    PubMed Central

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

    2016-01-01

    Background: 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. Objectives: To compare three options, four options, and five options MCQs test for the quality parameters – reliability, validity, item analysis, distracter analysis, and time analysis. Materials and Methods: Participants were 3rd 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. Results: 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. Conclusion: Assessment based on three option MCQs is can be preferred over four option and five option MCQs. PMID:27721545

  9. 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.

  10. 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

  11. A posteriori pointwise error estimates for the boundary element method

    SciTech Connect

    Paulino, G.H.; Gray, L.J.; Zarikian, V.

    1995-01-01

    This report presents a new approach for a posteriori pointwise error estimation in the boundary element method. The estimator relies upon the evaluation of hypersingular integral equations, and is therefore intrinsic to the boundary integral equation approach. This property allows some theoretical justification by mathematically correlating the exact and estimated errors. A methodology is developed for approximating the error on the boundary as well as in the interior of the domain. In the interior, error estimates for both the function and its derivatives (e.g. potential and interior gradients for potential problems, displacements and stresses for elasticity problems) are presented. Extensive computational experiments have been performed for the two dimensional Laplace equation on interior domains, employing Dirichlet and mixed boundary conditions. The results indicate that the error estimates successfully track the form of the exact error curve. Moreover, a reasonable estimate of the magnitude of the actual error is also obtained.

  12. Enabling Predictive Simulation and UQ of Complex Multiphysics PDE Systems by the Development of Goal-Oriented Variational Sensitivity Analysis and A Posteriori Error Estimation Methods

    SciTech Connect

    Ginting, Victor

    2014-03-15

    it was demonstrated that a posteriori analyses in general and in particular one that uses adjoint methods can accurately and efficiently compute numerical error estimates and sensitivity for critical Quantities of Interest (QoIs) that depend on a large number of parameters. Activities include: analysis and implementation of several time integration techniques for solving system of ODEs as typically obtained from spatial discretization of PDE systems; multirate integration methods for ordinary differential equations; formulation and analysis of an iterative multi-discretization Galerkin finite element method for multi-scale reaction-diffusion equations; investigation of an inexpensive postprocessing technique to estimate the error of finite element solution of the second-order quasi-linear elliptic problems measured in some global metrics; investigation of an application of the residual-based a posteriori error estimates to symmetric interior penalty discontinuous Galerkin method for solving a class of second order quasi-linear elliptic problems; a posteriori analysis of explicit time integrations for system of linear ordinary differential equations; derivation of accurate a posteriori goal oriented error estimates for a user-defined quantity of interest for two classes of first and second order IMEX schemes for advection-diffusion-reaction problems; Postprocessing finite element solution; and A Bayesian Framework for Uncertain Quantification of Porous Media Flows.

  13. 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).

  14. 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

  15. 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

  16. A posteriori subcell limiting of the discontinuous Galerkin finite element method for hyperbolic conservation laws

    NASA Astrophysics Data System (ADS)

    Dumbser, Michael; Zanotti, Olindo; Loubère, Raphaël; Diot, Steven

    2014-12-01

    The purpose of this work is to propose a novel a posteriori finite volume subcell limiter technique for the Discontinuous Galerkin finite element method for nonlinear systems of hyperbolic conservation laws in multiple space dimensions that works well for arbitrary high order of accuracy in space and time and that does not destroy the natural subcell resolution properties of the DG method. High order time discretization is achieved via a one-step ADER approach that uses a local space-time discontinuous Galerkin predictor method to evolve the data locally in time within each cell. Our new limiting strategy is based on the so-called MOOD paradigm, which a posteriori verifies the validity of a discrete candidate solution against physical and numerical detection criteria after each time step. Here, we employ a relaxed discrete maximum principle in the sense of piecewise polynomials and the positivity of the numerical solution as detection criteria. Within the DG scheme on the main grid, the discrete solution is represented by piecewise polynomials of degree N. For those troubled cells that need limiting, our new limiter approach recomputes the discrete solution by scattering the DG polynomials at the previous time step onto a set of Ns=2N+1 finite volume subcells per space dimension. A robust but accurate ADER-WENO finite volume scheme then updates the subcell averages of the conservative variables within the detected troubled cells. The recomputed subcell averages are subsequently gathered back into high order cell-centered DG polynomials on the main grid via a subgrid reconstruction operator. The choice of Ns=2N+1 subcells is optimal since it allows to match the maximum admissible time step of the finite volume scheme on the subgrid with the maximum admissible time step of the DG scheme on the main grid, minimizing at the same time also the local truncation error of the subcell finite volume scheme. It furthermore provides an excellent subcell resolution of

  17. A posteriori uncertainty quantification of PIV-based pressure data

    NASA Astrophysics Data System (ADS)

    Azijli, Iliass; Sciacchitano, Andrea; Ragni, Daniele; Palha, Artur; Dwight, Richard P.

    2016-05-01

    A methodology for a posteriori uncertainty quantification of pressure data retrieved from particle image velocimetry (PIV) is proposed. It relies upon the Bayesian framework, where the posterior distribution (probability distribution of the true velocity, given the PIV measurements) is obtained from the prior distribution (prior knowledge of properties of the velocity field, e.g., divergence-free) and the statistical model of PIV measurement uncertainty. Once the posterior covariance matrix of the velocity is known, it is propagated through the discretized Poisson equation for pressure. Numerical assessment of the proposed method on a steady Lamb-Oseen vortex shows excellent agreement with Monte Carlo simulations, while linear uncertainty propagation underestimates the uncertainty in the pressure by up to 30 %. The method is finally applied to an experimental test case of a turbulent boundary layer in air, obtained using time-resolved tomographic PIV. Simultaneously with the PIV measurements, microphone measurements were carried out at the wall. The pressure reconstructed from the tomographic PIV data is compared to the microphone measurements. Realizing that the uncertainty of the latter is significantly smaller than the PIV-based pressure, this allows us to obtain an estimate for the true error of the former. The comparison between true error and estimated uncertainty demonstrates the accuracy of the uncertainty estimates on the pressure. In addition, enforcing the divergence-free constraint is found to result in a significantly more accurate reconstructed pressure field. The estimated uncertainty confirms this result.

  18. A posteriori error estimates for finite volume approximations of elliptic equations on general surfaces

    SciTech Connect

    Ju, Lili; Tian, Li; Wang, Desheng

    2009-01-01

    In this paper, we present a residual-based a posteriori error estimate for the finite volume discretization of steady convection– diffusion–reaction equations defined on surfaces in R3, which are often implicitly represented as level sets of smooth functions. Reliability and efficiency of the proposed a posteriori error estimator are rigorously proved. Numerical experiments are also conducted to verify the theoretical results and demonstrate the robustness of the error estimator.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. A-Posteriori Error Estimation for Hyperbolic Conservation Laws with Constraint

    NASA Technical Reports Server (NTRS)

    Barth, Timothy

    2004-01-01

    This lecture considers a-posteriori error estimates for the numerical solution of conservation laws with time invariant constraints such as those arising in magnetohydrodynamics (MHD) and gravitational physics. Using standard duality arguments, a-posteriori error estimates for the discontinuous Galerkin finite element method are then presented for MHD with solenoidal constraint. From these estimates, a procedure for adaptive discretization is outlined. A taxonomy of Green's functions for the linearized MHD operator is given which characterizes the domain of dependence for pointwise errors. The extension to other constrained systems such as the Einstein equations of gravitational physics are then considered. Finally, future directions and open problems are discussed.

  4. Segmenting pectoralis muscle on digital mammograms by a Markov random field-maximum a posteriori model.

    PubMed

    Ge, Mei; Mainprize, James G; Mawdsley, Gordon E; Yaffe, Martin J

    2014-10-01

    Accurate and automatic segmentation of the pectoralis muscle is essential in many breast image processing procedures, for example, in the computation of volumetric breast density from digital mammograms. Its segmentation is a difficult task due to the heterogeneity of the region, neighborhood complexities, and shape variability. The segmentation is achieved by pixel classification through a Markov random field (MRF) image model. Using the image intensity feature as observable data and local spatial information as a priori, the posterior distribution is estimated in a stochastic process. With a variable potential component in the energy function, by the maximum a posteriori (MAP) estimate of the labeling image, given the image intensity feature which is assumed to follow a Gaussian distribution, we achieved convergence properties in an appropriate sense by Metropolis sampling the posterior distribution of the selected energy function. By proposing an adjustable spatial constraint, the MRF-MAP model is able to embody the shape requirement and provide the required flexibility for the model parameter fitting process. We demonstrate that accurate and robust segmentation can be achieved for the curving-triangle-shaped pectoralis muscle in the medio-lateral-oblique (MLO) view, and the semielliptic-shaped muscle in cranio-caudal (CC) view digital mammograms. The applicable mammograms can be either "For Processing" or "For Presentation" image formats. The algorithm was developed using 56 MLO-view and 79 CC-view FFDM "For Processing" images, and quantitatively evaluated against a random selection of 122 MLO-view and 173 CC-view FFDM images of both presentation intent types.

  5. Segmenting pectoralis muscle on digital mammograms by a Markov random field-maximum a posteriori model

    PubMed Central

    Ge, Mei; Mainprize, James G.; Mawdsley, Gordon E.; Yaffe, Martin J.

    2014-01-01

    Abstract. Accurate and automatic segmentation of the pectoralis muscle is essential in many breast image processing procedures, for example, in the computation of volumetric breast density from digital mammograms. Its segmentation is a difficult task due to the heterogeneity of the region, neighborhood complexities, and shape variability. The segmentation is achieved by pixel classification through a Markov random field (MRF) image model. Using the image intensity feature as observable data and local spatial information as a priori, the posterior distribution is estimated in a stochastic process. With a variable potential component in the energy function, by the maximum a posteriori (MAP) estimate of the labeling image, given the image intensity feature which is assumed to follow a Gaussian distribution, we achieved convergence properties in an appropriate sense by Metropolis sampling the posterior distribution of the selected energy function. By proposing an adjustable spatial constraint, the MRF-MAP model is able to embody the shape requirement and provide the required flexibility for the model parameter fitting process. We demonstrate that accurate and robust segmentation can be achieved for the curving-triangle-shaped pectoralis muscle in the medio-lateral-oblique (MLO) view, and the semielliptic-shaped muscle in cranio-caudal (CC) view digital mammograms. The applicable mammograms can be either “For Processing” or “For Presentation” image formats. The algorithm was developed using 56 MLO-view and 79 CC-view FFDM “For Processing” images, and quantitatively evaluated against a random selection of 122 MLO-view and 173 CC-view FFDM images of both presentation intent types. PMID:26158068

  6. Maximum a posteriori blind image deconvolution with Huber-Markov random-field regularization.

    PubMed

    Xu, Zhimin; Lam, Edmund Y

    2009-05-01

    We propose a maximum a posteriori blind deconvolution approach using a Huber-Markov random-field model. Compared with the conventional maximum-likelihood method, our algorithm not only suppresses noise effectively but also significantly alleviates the artifacts produced by the deconvolution process. The performance of this method is demonstrated by computer simulations.

  7. 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…

  8. 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…

  9. Application of a posteriori error estimates for the steady Stokes-Brinkman equation in 2D

    NASA Astrophysics Data System (ADS)

    Hasal, Martin; Burda, Pavel

    2016-06-01

    The paper deals with the Stokes-Brinkman equation. We investigate a posteriori error estimates for the Stokes-Brinkman equation on two-dimensional polygonal domains. Special attention is paid to the value of the hydraulic conductivity coefficients. We present numerical results for an incompressible flow problem in a domain with corners.

  10. FORTRAN IV Program for Analysis of Covariance with A Priori or A Posteriori Mean Comparisons

    ERIC Educational Resources Information Center

    Fordyce, Michael W.

    1977-01-01

    A flexible Fortran program for computing a complete analysis of covariance is described. Requiring minimal core space, the program provides all group and overall summary statistics for the analysis, a test of homogeneity of regression, and all posttest mean comparisons for a priori or a posteriori testing. (Author/JKS)

  11. [Correlations between colorimetric parameters of teeth, eyes and skin. Perspectives in the choice of tooth shade for complete denture].

    PubMed

    Seck, A; Guèye, M; Dieng, L; Mbodj, E B; Ndiaye, C; Seck, M T; Lo, A S; Ngom, P I

    2013-09-01

    Rehabilitation with complete denture include among other objectives, improvement of facial and dental esthetics. To these ends, the artificial teeth should mimic as far as possible, healthy and natural dentition. The main objective of this study was to investigate factors associated with tooth color among black African subjects. One hundred and two subjects (72 men and 30 women) were included in this investigation. The colorimetric parameters of their teeth as well as those of the conjunctiva of their eyes and skin were recorded from standardized photographs. Two software, Mesurim and Photoshop were used for that purpose. Univariate and linear regression analysis were run to assess the association between tooth color and the variables age, gender and colorimetric parameters of eyes and skin. It appears from the result of this study that tooth color was positively and significantly associated with age. Stepwise multiple regression analysis further revealed that tooth hue can be best predicted by a combination of skin complexion and brightness and eye lightness.

  12. 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%.

  13. Nonmarket valuation of water quality in a rural transition economy in Turkey applying an a posteriori bid design

    NASA Astrophysics Data System (ADS)

    Bederli Tümay, Aylin; Brouwer, Roy

    2007-05-01

    In this paper, we investigate the economic benefits associated with public investments in wastewater treatment in one of the special protected areas along Turkey's touristic Mediterranean coast, the Köyceǧiz-Dalyan watershed. The benefits, measured in terms of boatable, fishable, swimmable and drinkable water quality, are estimated using a public survey format following the contingent valuation (CV) method. The study presented here is the first of its kind in Turkey. The study's main objective is to assess public perception, understanding, and valuation of improved wastewater treatment facilities in the two largest population centers in the watershed, facing the same water pollution problems as a result of lack of appropriate wastewater treatment. We test the validity and reliability of the application of the CV methodology to this specific environmental problem in a rural transition economy and evaluate the transferability of the results within the watershed. In order to facilitate willingness to pay (WTP) value elicitation we apply a novel dichotomous choice procedure where bid design takes place a posteriori instead of a priori. The statistical efficiency of different bid vectors is evaluated in terms of the estimated welfare measures' mean square errors using Monte Carlo simulation. The robustness of bid function specification is analyzed through average WTP and standard deviation estimated using parametric and nonparametric methods.

  14. 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%. PMID:27250295

  15. Maximum a posteriori estimation of crystallographic phases in X-ray diffraction tomography

    PubMed Central

    Gürsoy, Doĝa; Biçer, Tekin; Almer, Jonathan D.; Kettimuthu, Raj; Stock, Stuart R.; De Carlo, Francesco

    2015-01-01

    A maximum a posteriori approach is proposed for X-ray diffraction tomography for reconstructing three-dimensional spatial distribution of crystallographic phases and orientations of polycrystalline materials. The approach maximizes the a posteriori density which includes a Poisson log-likelihood and an a priori term that reinforces expected solution properties such as smoothness or local continuity. The reconstruction method is validated with experimental data acquired from a section of the spinous process of a porcine vertebra collected at the 1-ID-C beamline of the Advanced Photon Source, at Argonne National Laboratory. The reconstruction results show significant improvement in the reduction of aliasing and streaking artefacts, and improved robustness to noise and undersampling compared to conventional analytical inversion approaches. The approach has the potential to reduce data acquisition times, and significantly improve beamtime efficiency. PMID:25939627

  16. 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. PMID:24418010

  17. 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.

  18. The Impact of Microphysical Schemes and Parameter Choices on MM5 Simulations of Warm-Season High Latitude Cloud and Precipitation Systems

    NASA Astrophysics Data System (ADS)

    Tilley, J. S.; Kramm, G.

    2002-12-01

    Recently, an increasing variety of schemes to represent cloud microphysical processes have been incorporated into mesoscale models. These schemes, which are usually "bulk" approaches to the microphysics in order to reduce computational cost, range from the rather simple to relatively complex in terms of the processes represented and their formulation. The schemes are based upon various theoretical, laboratory, field measurement, and cloud modeling studies that have appeared in the literature over the past forty years, studies that have focused almost exclusively on mid-latitude and tropical areas. While significant effort has been exercised to validate such microphysical schemes in mid-latitude and tropical environments, relatively little systematic work has been done to consider how such schemes would behave in high latitudes. This is particularly the case for sophisticated regional models such as the Penn State/NCAR MM5, where the microphysical scheme used must interact with other physical schemes in complex and nonlinear ways. This issue is an important one to consider from the perspectives of aviation weather, quantitative precipitation forecasts and radiative transfer, the latter having importance to regional and global climate modeling applications. In this paper we examine the impacts of different cloud microphysical treatments on MM5 simulations of warm season high latitude cloud and precipitation systems. We examine the sensitivity of simulated mesoscale cloud, precipitation and dynamic fields to (1) the choice of the various microphysical schemes routinely available with the MM5 system, and (2) modifications to key parameters (baseline ice nuclei concentrations, temperature thresholds and supersaturation thresholds) within individual parameterization schemes. Our experiments focus on a period during mid-June 1998 during the Surface Heat Budget of the Arctic (SHEBA) Experiment. Through the period there is considerable cloud property data available over the

  19. An a posteriori error estimator for shape optimization: application to EIT

    NASA Astrophysics Data System (ADS)

    Giacomini, M.; Pantz, O.; Trabelsi, K.

    2015-11-01

    In this paper we account for the numerical error introduced by the Finite Element approximation of the shape gradient to construct a guaranteed shape optimization method. We present a goal-oriented strategy inspired by the complementary energy principle to construct a constant-free, fully-computable a posteriori error estimator and to derive a certified upper bound of the error in the shape gradient. The resulting Adaptive Boundary Variation Algorithm (ABVA) is able to identify a genuine descent direction at each iteration and features a reliable stopping criterion for the optimization loop. Some preliminary numerical results for the inverse identification problem of Electrical Impedance Tomography are presented.

  20. Phylogenomics and a posteriori data partitioning resolve the Cretaceous angiosperm radiation Malpighiales.

    PubMed

    Xi, Zhenxiang; Ruhfel, Brad R; Schaefer, Hanno; Amorim, André M; Sugumaran, M; Wurdack, Kenneth J; Endress, Peter K; Matthews, Merran L; Stevens, Peter F; Mathews, Sarah; Davis, Charles C

    2012-10-23

    The angiosperm order Malpighiales includes ~16,000 species and constitutes up to 40% of the understory tree diversity in tropical rain forests. Despite remarkable progress in angiosperm systematics during the last 20 y, relationships within Malpighiales remain poorly resolved, possibly owing to its rapid rise during the mid-Cretaceous. Using phylogenomic approaches, including analyses of 82 plastid genes from 58 species, we identified 12 additional clades in Malpighiales and substantially increased resolution along the backbone. This greatly improved phylogeny revealed a dynamic history of shifts in net diversification rates across Malpighiales, with bursts of diversification noted in the Barbados cherries (Malpighiaceae), cocas (Erythroxylaceae), and passion flowers (Passifloraceae). We found that commonly used a priori approaches for partitioning concatenated data in maximum likelihood analyses, by gene or by codon position, performed poorly relative to the use of partitions identified a posteriori using a Bayesian mixture model. We also found better branch support in trees inferred from a taxon-rich, data-sparse matrix, which deeply sampled only the phylogenetically critical placeholders, than in trees inferred from a taxon-sparse matrix with little missing data. Although this matrix has more missing data, our a posteriori partitioning strategy reduced the possibility of producing multiple distinct but equally optimal topologies and increased phylogenetic decisiveness, compared with the strategy of partitioning by gene. These approaches are likely to help improve phylogenetic resolution in other poorly resolved major clades of angiosperms and to be more broadly useful in studies across the Tree of Life.

  1. A posteriori error estimates for the Johnson–Nédélec FEM–BEM coupling

    PubMed Central

    Aurada, M.; Feischl, M.; Karkulik, M.; Praetorius, D.

    2012-01-01

    Only very recently, Sayas [The validity of Johnson–Nédélec's BEM-FEM coupling on polygonal interfaces. SIAM J Numer Anal 2009;47:3451–63] proved that the Johnson–Nédélec one-equation approach from [On the coupling of boundary integral and finite element methods. Math Comput 1980;35:1063–79] provides a stable coupling of finite element method (FEM) and boundary element method (BEM). In our work, we now adapt the analytical results for different a posteriori error estimates developed for the symmetric FEM–BEM coupling to the Johnson–Nédélec coupling. More precisely, we analyze the weighted-residual error estimator, the two-level error estimator, and different versions of (h−h/2)-based error estimators. In numerical experiments, we use these estimators to steer h-adaptive algorithms, and compare the effectivity of the different approaches. PMID:22347772

  2. Maximum a posteriori estimation of spectral reflectance from color image and multipoint spectral measurements.

    PubMed

    Murakami, Yuri; Ietomi, Kunihiko; Yamaguchi, Masahiro; Ohyama, Nagaaki

    2007-10-01

    Accurate color image reproduction under arbitrary illumination can be realized if the spectral reflectance functions in a scene are obtained. Although multispectral imaging is one of the promising methods to obtain the reflectance of a scene, it is expected to reduce the number of color channels without significant loss of accuracy. This paper presents what we believe to be a new method for estimating spectral reflectance functions from color image and multipoint spectral measurements based on maximum a posteriori (MAP) estimation. Multipoint spectral measurements are utilized as auxiliary information to improve the accuracy of spectral reflectance estimated from image data. Through simulations, it is confirmed that the proposed method improves the estimation accuracy, particularly when a scene includes subjects that belong to various categories.

  3. A posteriori error analysis for a cut cell finite volume method

    SciTech Connect

    Haiying Wang; Michael Pernice; Simon Tavener; Don Estep

    2011-09-01

    We study the solution of a diffusive process in a domain where the diffusion coefficient changes discontinuously across a curved interface. We consider discretizations that use regularly-shaped meshes, so that the interface “cuts” through the cells (elements or volumes) without respecting the regular geometry of the mesh. Consequently, the discontinuity in the diffusion coefficients has a strong impact on the accuracy and convergence of the numerical method. This motivates the derivation of computational error estimates that yield accurate estimates for specified quantities of interest. For this purpose, we adapt the well-known adjoint based a posteriori error analysis technique used for finite element methods. In order to employ this method, we describe a systematic approach to discretizing a cut-cell problem that handles complex geometry in the interface in a natural fashion yet reduces to the well-known Ghost Fluid Method in simple cases. We test the accuracy of the estimates in a series of examples.

  4. Real-time maximum a-posteriori image reconstruction for fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Jabbar, Anwar A.; Dilipkumar, Shilpa; C K, Rasmi; Rajan, K.; Mondal, Partha P.

    2015-08-01

    Rapid reconstruction of multidimensional image is crucial for enabling real-time 3D fluorescence imaging. This becomes a key factor for imaging rapidly occurring events in the cellular environment. To facilitate real-time imaging, we have developed a graphics processing unit (GPU) based real-time maximum a-posteriori (MAP) image reconstruction system. The parallel processing capability of GPU device that consists of a large number of tiny processing cores and the adaptability of image reconstruction algorithm to parallel processing (that employ multiple independent computing modules called threads) results in high temporal resolution. Moreover, the proposed quadratic potential based MAP algorithm effectively deconvolves the images as well as suppresses the noise. The multi-node multi-threaded GPU and the Compute Unified Device Architecture (CUDA) efficiently execute the iterative image reconstruction algorithm that is ≈200-fold faster (for large dataset) when compared to existing CPU based systems.

  5. A Posteriori Error Estimation for Finite Volume and Finite Element Approximations Using Broken Space Approximation

    NASA Technical Reports Server (NTRS)

    Barth, Timothy J.; Larson, Mats G.

    2000-01-01

    We consider a posteriori error estimates for finite volume and finite element methods on arbitrary meshes subject to prescribed error functionals. Error estimates of this type are useful in a number of computational settings: (1) quantitative prediction of the numerical solution error, (2) adaptive meshing, and (3) load balancing of work on parallel computing architectures. Our analysis recasts the class of Godunov finite volumes schemes as a particular form of discontinuous Galerkin method utilizing broken space approximation obtained via reconstruction of cell-averaged data. In this general framework, weighted residual error bounds are readily obtained using duality arguments and Galerkin orthogonality. Additional consideration is given to issues such as nonlinearity, efficiency, and the relationship to other existing methods. Numerical examples are given throughout the talk to demonstrate the sharpness of the estimates and efficiency of the techniques. Additional information is contained in the original.

  6. Conjugate quasilinear Dirichlet and Neumann problems and a posteriori error bounds

    NASA Technical Reports Server (NTRS)

    Lavery, J. E.

    1976-01-01

    Quasilinear Dirichlet and Neumann problems on a rectangle D with boundary D prime are considered. Using these concepts, conjugate problems, that is, a pair of one Dirichlet and one Neumann problem, the minima of the energies of which add to zero, are introduced. From the concept of conjugate problems, two-sided bounds for the energy of the exact solution of any given Dirichlet or Neumann problem are constructed. These two-sided bounds for the energy at the exact solution are in turn used to obtain a posteriori error bounds for the norm of the difference of the approximate and exact solutions of the problem. These bounds do not involve the unknown exact solution and are easily constructed numerically.

  7. Edge-based a posteriori error estimators for generation of d-dimensional quasi-optimal meshes

    SciTech Connect

    Lipnikov, Konstantin; Agouzal, Abdellatif; Vassilevski, Yuri

    2009-01-01

    We present a new method of metric recovery for minimization of L{sub p}-norms of the interpolation error or its gradient. The method uses edge-based a posteriori error estimates. The method is analyzed for conformal simplicial meshes in spaces of arbitrary dimension d.

  8. FORTRAN IV Program for One-Way Analysis of Variance with A Priori or A Posteriori Mean Comparisons

    ERIC Educational Resources Information Center

    Fordyce, Michael W.

    1977-01-01

    A flexible Fortran program for computing one way analysis of variance is described. Requiring minimal core space, the program provides a variety of useful group statistics, all summary statistics for the analysis, and all mean comparisons for a priori or a posteriori testing. (Author/JKS)

  9. 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

  10. Choice Plans: A Glossary.

    ERIC Educational Resources Information Center

    Heleen, Owen

    1992-01-01

    Choice plans include private schools (voucher plans, tax credits and deductions, and contract services and charter plans) and public schools (intradistrict choice, interdistrict choice, and statewide choice). Issues spanning both areas are those of curricular choice and residential choice. (SLD)

  11. Phylogenetic assignment of Mycobacterium tuberculosis Beijing clinical isolates in Japan by maximum a posteriori estimation.

    PubMed

    Seto, Junji; Wada, Takayuki; Iwamoto, Tomotada; Tamaru, Aki; Maeda, Shinji; Yamamoto, Kaori; Hase, Atsushi; Murakami, Koichi; Maeda, Eriko; Oishi, Akira; Migita, Yuji; Yamamoto, Taro; Ahiko, Tadayuki

    2015-10-01

    Intra-species phylogeny of Mycobacterium tuberculosis has been regarded as a clue to estimate its potential risk to develop drug-resistance and various epidemiological tendencies. Genotypic characterization of variable number of tandem repeats (VNTR), a standard tool to ascertain transmission routes, has been improving as a public health effort, but determining phylogenetic information from those efforts alone is difficult. We present a platform based on maximum a posteriori (MAP) estimation to estimate phylogenetic information for M. tuberculosis clinical isolates from individual profiles of VNTR types. This study used 1245 M. tuberculosis clinical isolates obtained throughout Japan for construction of an MAP estimation formula. Two MAP estimation formulae, classification of Beijing family and other lineages, and classification of five Beijing sublineages (ST11/26, STK, ST3, and ST25/19 belonging to the ancient Beijing subfamily and modern Beijing subfamily), were created based on 24 loci VNTR (24Beijing-VNTR) profiles and phylogenetic information of the isolates. Recursive estimation based on the formulae showed high concordance with their authentic phylogeny by multi-locus sequence typing (MLST) of the isolates. The formulae might further support phylogenetic estimation of the Beijing lineage M. tuberculosis from the VNTR genotype with various geographic backgrounds. These results suggest that MAP estimation can function as a reliable probabilistic process to append phylogenetic information to VNTR genotypes of M. tuberculosis independently, which might improve the usage of genotyping data for control, understanding, prevention, and treatment of TB.

  12. 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.

  13. On Evaluation of Recharge Model Uncertainty: a Priori and a Posteriori

    SciTech Connect

    Ming Ye; Karl Pohlmann; Jenny Chapman; David Shafer

    2006-01-30

    Hydrologic environments are open and complex, rendering them prone to multiple interpretations and mathematical descriptions. Hydrologic analyses typically rely on a single conceptual-mathematical model, which ignores conceptual model uncertainty and may result in bias in predictions and under-estimation of predictive uncertainty. This study is to assess conceptual model uncertainty residing in five recharge models developed to date by different researchers based on different theories for Nevada and Death Valley area, CA. A recently developed statistical method, Maximum Likelihood Bayesian Model Averaging (MLBMA), is utilized for this analysis. In a Bayesian framework, the recharge model uncertainty is assessed, a priori, using expert judgments collected through an expert elicitation in the form of prior probabilities of the models. The uncertainty is then evaluated, a posteriori, by updating the prior probabilities to estimate posterior model probability. The updating is conducted through maximum likelihood inverse modeling by calibrating the Death Valley Regional Flow System (DVRFS) model corresponding to each recharge model against observations of head and flow. Calibration results of DVRFS for the five recharge models are used to estimate three information criteria (AIC, BIC, and KIC) used to rank and discriminate these models. Posterior probabilities of the five recharge models, evaluated using KIC, are used as weights to average head predictions, which gives posterior mean and variance. The posterior quantities incorporate both parametric and conceptual model uncertainties.

  14. Level Set Segmentation of Medical Images Based on Local Region Statistics and Maximum a Posteriori Probability

    PubMed Central

    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. PMID:24302974

  15. Resolution enhancement of hyperspectral imagery using maximum a posteriori estimation with a stochastic mixing model

    NASA Astrophysics Data System (ADS)

    Eismann, Michael Theodore

    A maximum a posteriori estimation method is developed and tested for enhancing the spatial resolution of hyperspectral imagery using higher resolution, coincident, panchromatic or multispectral imagery. The approach incorporates a stochastic mixing model of the underlying spectral scene content to develop a cost function that simultaneously optimizes the estimated hyperspectral scene relative to the observed hyperspectral and auxiliary imagery, as well as the local statistics of the spectral mixing model. The incorporation of the stochastic mixing model is found to be the key ingredient to reconstructing sub-pixel spectral information. It provides the necessary constraints for establishing a well-conditioned linear system of equations that can be solved for the high resolution image estimate. The research presented includes a mathematical formulation of the estimation approach and stochastic mixing model, as well as enhancement results for a variety of both synthetic and actual imagery. Both direct and iterative solution methodologies are developed, the latter being necessary to effectively treat imagery with arbitrarily specified spectral and spatial response functions. The performance of the method is qualitatively and quantitatively compared to that of previously developed resolution enhancement approaches. It is found that this novel approach is generally able to reconstruct sub-pixel information in several principal components of the high resolution hyperspectral image estimate. In contrast, the enhancement for conventional methods such as principal component substitution and least-squares estimation is mostly limited to the first principal component.

  16. Parameter adaptive estimation of random processes

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Vanlandingham, H. F.

    1975-01-01

    This paper is concerned with the parameter adaptive least squares estimation of random processes. The main result is a general representation theorem for the conditional expectation of a random variable on a product probability space. Using this theorem along with the general likelihood ratio expression, the least squares estimate of the process is found in terms of the parameter conditioned estimates. The stochastic differential for the a posteriori probability and the stochastic differential equation for the a posteriori density are found by using simple stochastic calculus on the representations obtained. The results are specialized to the case when the parameter has a discrete distribution. The results can be used to construct an implementable recursive estimator for certain types of nonlinear filtering problems. This is illustrated by some simple examples.

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

    SciTech Connect

    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 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 hierarchical 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.

  18. A-priori and a-posteriori assessment of SGS models for shock-boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Jammalamadaka, Avinash; Li, Zhaorui; Jaberi, Farhad

    2010-11-01

    A-priori and a-posteriori assessments of subgrid-scale (SGS) large-eddy simulation (LES) models are made for an incident shock wave interacting with a Mach 2 flat-plate supersonic turbulent boundary layer using direct numerical simulation (DNS) data. The governing equations for DNS and LES are solved using the seventh-order Monotonicity Preserving scheme for Euler fluxes and the sixth-order compact scheme for viscous terms. The SGS models tested included constant coefficient and dynamic eddy-viscosity and similarity models. A-priori tests confirm that the similarity- and mixed-type models are superior to those developed based purely on eddy-viscosity assumption. However, some of the eddy-viscosity models still perform adequately in a-posteriori tests. Overall, dynamic models show reasonably good agreement with the DNS data.

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

    DOE PAGESBeta

    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

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

    SciTech Connect

    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 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.

  1. Choice Matters.

    ERIC Educational Resources Information Center

    Hicks, Darcy

    2001-01-01

    Describes how the author allows the children to make choices about their art and writing, enabling them to make connections between their own lives and work. Suggests that educators need to provide doorways to the things that give students ideas: books, music, objects, pictures, smells, sounds, and textures. (SG)

  2. 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

  3. 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.

  4. The choice of the mathematical method for prediction of electrochemical accumulator parameters value in power installations of space-rocket objects

    NASA Astrophysics Data System (ADS)

    Bezruchko, K. V.; Davidov, A. O.; Katorgina, J. G.; Logvin, V. M.; Kharchenko, A. A.

    2013-11-01

    The review and analysis of several mathematical methods for prediction of electrochemical accumulator parameters are provided in the article: according to the mathematical expectation, the latest entry, a statistical prediction, Box-Jenkins model, decomposition Volta, ARMA, ARIMA and Kalman filter. The results of these methods for prediction of the electrochemical battery 22НКГ-4CK characteristics which is a part of spacecraft power plant of the “Mikrosputnik” type are given. Possible usage of these methods for long prediction of electrochemical accumulator characteristics on space-rocket objects power plants is showed.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Choice in Public Education.

    ERIC Educational Resources Information Center

    Young, Timothy W.; Clinchy, Evans

    There has been much recent debate in both educational and political circles about the utility of choice as a means of improving the educational system. This book argues that any discussion of choice must address choice in public schools. The book is organized into seven chapters. Chapter 1 provides an overview of choice in public education,…

  10. Myths of Educational Choice.

    ERIC Educational Resources Information Center

    Pearson, Judith

    This book presents concerns and raises questions about the choice programs being proposed and implemented around the United States. It argues that poorly conceived, hastily enacted choice programs may do more harm than good. The demand for educational choice may result in lost opportunities for students (some groups more than others), weakened…

  11. 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…

  12. A comparative estimation of the errors in the sunspot coordinate catalog compiled at Cuba and the methods of their a posteriori decrease.

    NASA Astrophysics Data System (ADS)

    Nagovitsyn, Yu. A.; Nikonov, O. V.; Perez Doval, J.

    1992-06-01

    A comparison of the accuracy of the Cuba, Greenwich and Debrecen catalogs of sunspot coordinates has been made. A new method for a posteriori decrease of coordinate errors is given. The following conclusions have been made: 1. The accuracy of absolute heliographic coordinates for the Cuban catalog is 0.26 and for the Greenwich catalog is 0.32 of the heliographic degree. 2. Reduction to smoothed coordinate values improves the accuracy by a factor of 1.5. 3. Reduction values within the frame of the proposed technique REPORT to "pseudorelative" coordinates enables an improvement of the initial accuracy of sunspot coordinate measurement by 5 - 7 times.

  13. Linear Deterministic Accumulator Models of Simple Choice

    PubMed Central

    Heathcote, Andrew; Love, Jonathon

    2012-01-01

    We examine theories of simple choice as a race among evidence accumulation processes. We focus on the class of deterministic race models, which assume that the effects of fluctuations in the parameters of the accumulation processes between-choice trials (between-choice noise) dominate the effects of fluctuations occurring while making a choice (within-choice noise) in behavioral data (i.e., response times and choices). The latter deterministic approximation, when combined with the assumption that accumulation is linear, leads to a class of models that can be readily applied to simple-choice behavior because they are computationally tractable. We develop a new and mathematically simple exemplar within the class of linear deterministic models, the Lognormal race (LNR). We then examine how the LNR, and another widely applied linear deterministic model, Brown and Heathcote’s (2008) LBA, account for a range of benchmark simple-choice effects in lexical-decision task data reported by Wagenmakers et al. (2008). Our results indicate that the LNR provides an accurate description of this data. Although the LBA model provides a slightly better account, both models support similar psychological conclusions. PMID:22936920

  14. 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…

  15. More Choice, Less Crime

    ERIC Educational Resources Information Center

    Dills, Angela K.; Hernandez-Julian, Rey

    2011-01-01

    Previous research debates whether public school choice improves students' academic outcomes, but there is little examination of its effects on their nonacademic outcomes. We use data from a nationally representative sample of high school students, a previously developed Tiebout choice measure, and metropolitan-level data on teenage arrest rates to…

  16. Latinos and School Choice

    ERIC Educational Resources Information Center

    Gastic, Billie; Coronado, Diana Salas

    2011-01-01

    The authors describe how Latino students are underrepresented in public schools of choice. They provide evidence to refute the claim that Latino students who choose to leave assigned public schools enroll in religious schools instead. Charter schools stand out as the type of public schools of choice where Latino students are well represented.…

  17. The Illusion of Choice

    ERIC Educational Resources Information Center

    Chitty, Clyde

    2004-01-01

    Both New Labour and the Conservatives are keen to emphasise choice and diversity in crucial areas of public provision--and particularly with regard to education and health. In this article, "FORUM" co-Editor Clyde Chitty concentrates on recent proposals by the two main parties for promoting greater choice in secondary schooling in England. This…

  18. Your Genes, Your Choices

    MedlinePlus

    Table of Contents Your Genes, Your Choices describes the Human Genome Project, the science behind it, and the ethical, legal, and social issues that are ... Nothing could be further from the truth. Your Genes, Your Choices points out how the progress of ...

  19. 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 programs. Yet education…

  20. Choice: The Historical Perspective.

    ERIC Educational Resources Information Center

    Wagoner, Jennings L., Jr.

    The issue of choice in U.S. education is traced historically. Consideration is given to the purposes of publicly supported education and reasons underlying the historic distinction between public and private education. It is suggested that the issue of choice concerns the rights and obligations of the individual and the state. The relationship…

  1. Haptic choice blindness

    PubMed Central

    Steenfeldt-Kristensen, Catherine; Thornton, Ian M.

    2013-01-01

    Choice blindness is the failure to notice a mismatch between intention and outcome when making decisions. It is unknown whether choice blindness occurs when participants have extended interaction with real objects. Here, we examined the case when objects could be touched but not seen. Participants examined pairs of common, everyday objects inside a specially constructed box where a silent turntable was used to switch objects between initial choice and later justification. For similar pairs of objects, we found detection rates of around 22%, consistent with previous studies of choice blindness. For pairs consisting of more distinctive exemplars, the detection rate rose to 70%. Our results indicate that choice blindness does occur after haptic interaction with real objects, but is strongly modulated by similarity. PMID:23799197

  2. Estimating random signal parameters from noisy images with nuisance parameters

    PubMed Central

    Whitaker, Meredith Kathryn; Clarkson, Eric; Barrett, Harrison H.

    2008-01-01

    In a pure estimation task, an object of interest is known to be present, and we wish to determine numerical values for parameters that describe the object. This paper compares the theoretical framework, implementation method, and performance of two estimation procedures. We examined the performance of these estimators for tasks such as estimating signal location, signal volume, signal amplitude, or any combination of these parameters. The signal is embedded in a random background to simulate the effect of nuisance parameters. First, we explore the classical Wiener estimator, which operates linearly on the data and minimizes the ensemble mean-squared error. The results of our performance tests indicate that the Wiener estimator can estimate amplitude and shape once a signal has been located, but is fundamentally unable to locate a signal regardless of the quality of the image. Given these new results on the fundamental limitations of Wiener estimation, we extend our methods to include more complex data processing. We introduce and evaluate a scanning-linear estimator that performs impressively for location estimation. The scanning action of the estimator refers to seeking a solution that maximizes a linear metric, thereby requiring a global-extremum search. The linear metric to be optimized can be derived as a special case of maximum a posteriori (MAP) estimation when the likelihood is Gaussian and a slowly varying covariance approximation is made. PMID:18545527

  3. Colorado's clean energy choices

    SciTech Connect

    Strawn, N.; Jones, J.

    2000-04-15

    The daily choices made as consumers affect the environment and the economy. Based on the state of today's technology and economics, Colorado consumers can include energy efficiency and renewable energy into many aspects of their lives. These choices include where they obtain electricity, how they use energy at home, and how they transport themselves from one place to another. In addition to outlining how they can use clean energy, Colorado's Clean Energy Choices gives consumers contacts and links to Web sites for where to get more information.

  4. 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. PMID:22024661

  5. Sequential sampling and paradoxes of risky choice.

    PubMed

    Bhatia, Sudeep

    2014-10-01

    The common-ratio, common-consequence, reflection, and event-splitting effects are some of the best-known findings in decision-making research. They represent robust violations of expected utility theory, and together form a benchmark against which descriptive theories of risky choice are tested. These effects are not currently predicted by sequential sampling models of risky choice, such as decision field theory (Busemeyer & Townsend 1993). This paper, however, shows that a minor extension to decision field theory, which allows for stochastic error in event sampling, can provide a parsimonious, cognitively plausible explanation for these effects. Moreover, these effects are guaranteed to emerge for a large range of parameter values, including best-fit parameters obtained from preexisting choice data. PMID:24898202

  6. Choice and conditioned reinforcement.

    PubMed

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

    1991-03-01

    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.

  7. 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.

  8. Fixing the c Parameter in the Three-Parameter Logistic Model

    ERIC Educational Resources Information Center

    Han, Kyung T.

    2012-01-01

    For several decades, the "three-parameter logistic model" (3PLM) has been the dominant choice for practitioners in the field of educational measurement for modeling examinees' response data from multiple-choice (MC) items. Past studies, however, have pointed out that the c-parameter of 3PLM should not be interpreted as a guessing parameter. This…

  9. Measuring improved patient choice.

    PubMed

    Holmes-Rovner, M; Rovner, D R

    2000-08-01

    Patient decision support (PDS) tools or decision aids have been developed as adjuncts to the clinical encounter. Their aim is to support evidence-based patient choice. Clinical trials of PDS tools have used an array of outcome measures to determine efficacy, including knowledge, satisfaction, health status and consistency between patient choice and values. This paper proposes that the correlation between 'subjective expected utility' (SEU) and decision may be the best primary endpoint for trials. SEU is a measure usually used in behavioural decision theory. The paper first describes how decision support tools may use decision analysis to structure the presentation of evidence and guide patient decision-making. Uses of expected utility (EU) are suggested for evaluating PDS tools when improving population health status is the objective. SEU is the theoretically better measure when internal consistency of patient choices is the objective. PMID:11083037

  10. The problem of choice

    PubMed Central

    Naqvi, Hassan R; Mathur, Shawn; Covarrubias, David; Curcio, Josephine A; Schmidt, Christian

    2008-01-01

    Convictions are a driving force for actions. Considering that every individual has a different set of convictions and larger groups act once a consensus decision is reached, one can see that debate is an inherent exercise in decision-making. This requires a sustainably generated surplus to allow time for intellectual exchange, gathering of information and dissemination of findings. It is essential that the full spectrum of options remain treated equally. At the end of this process, a choice has to be made. Looking back at a later time point, a retrospective analysis sometimes reveals that the choice was neither completely free nor a truly conscious one. Leaving the issue of consequences of a once made decision aside, we wish to contribute to the debate of the problem of choice. PMID:19025607

  11. 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.

  12. Special Issue Topic: School Choice.

    ERIC Educational Resources Information Center

    Brogan, Bernard R.; And Others

    1991-01-01

    Includes "The Choice Movement" (Brogan); "Choice in American Education" (Witte); "Role of Parents in Education" (Mawdsley); "As Arrows in the Hand" (Coons); "Vouchers in Wisconsin" (Underwood); "Milwaukee Parental Choice Program (MPCP)" (Grover); "Civil Liberties and the MPCP" (Bolick); "Comments on School Choice" (Jauch); "Two Classes of…

  13. Optimal filtration of the atmospheric parameters profiles

    NASA Technical Reports Server (NTRS)

    Zuev, V. E.; Glazov, G. N.; Igonin, G. M.

    1986-01-01

    The idea of optimal Marcovian filtration of fluctuating profiles from lidar signals is developed but as applied to a double-frequency sounding which allows the use of large cross sections of elastic scattering and correct separation of the contributions due to aerosol and Rayleigh scatterings from the total lidar return. The filtration efficiency is shown under different conditions of sounding using a computer model. The accuracy of restituted profiles (temperature, pressure, density) is determined by the elements of a posteriori matrix K. The results obtained allow the determination of the lidar power required for providing the necessary accuracy of restitution of the atmospheric parameter profiles at chosen wavelengths of sounding in the ultraviolet and visible range.

  14. Learning from School Choice.

    ERIC Educational Resources Information Center

    Peterson, Paul E., Ed.; Hassel, Bryan C., Ed.

    This volume contains revised versions of 16 essays presented at a conference, "Rethinking School Governance," hosted by Harvard's Program on Education Policy and Governance in June 1997. Part 1, "Introduction," contains two chapters: (1) "School Choice: A Report Card" (Paul E. Peterson); and (2) "The Case for Charter Schools" (Bryan C. Hassel).…

  15. Saying No to "Choice."

    ERIC Educational Resources Information Center

    Penning, Nick

    1992-01-01

    Name of Bush Administration's choice game is publicly financed vouchers allowing those already sending their children to private and parochial schools to avoid tuition fees at taxpayer expense. Although private schools administer entrance exams, public schools accept every child regardless of academic record, status, or race. U.S. Senate recently…

  16. Finland's energy choices

    SciTech Connect

    Jeffs, E.

    1994-01-01

    In Finland, a decision on a fifth nuclear power plant is stalled for at least two years. This leaves the country with a difficult choice for meeting anticipated electricity demand in the years ahead. This article examines the various energy alternatives of Finland and the political aspects of their energy development.

  17. Choices, Frameworks and Refinement

    NASA Technical Reports Server (NTRS)

    Campbell, Roy H.; Islam, Nayeem; Johnson, Ralph; Kougiouris, Panos; Madany, Peter

    1991-01-01

    In this paper we present a method for designing operating systems using object-oriented frameworks. A framework can be refined into subframeworks. Constraints specify the interactions between the subframeworks. We describe how we used object-oriented frameworks to design Choices, an object-oriented operating system.

  18. The Choice for Learning

    ERIC Educational Resources Information Center

    Bennett, Scott

    2006-01-01

    We are building conventional library space without making the paradigm shift our digital environment requires. The chief obstacles to change lie in our conception of readers as information consumers, in our allegiance to library operations as the drivers of library design, and in the choice made between foundational and non-foundational views of…

  19. Deterministic Walks with Choice

    SciTech Connect

    Beeler, Katy E.; Berenhaut, Kenneth S.; Cooper, Joshua N.; Hunter, Meagan N.; Barr, Peter S.

    2014-01-10

    This paper studies deterministic movement over toroidal grids, integrating local information, bounded memory and choice at individual nodes. The research is motivated by recent work on deterministic random walks, and applications in multi-agent systems. Several results regarding passing tokens through toroidal grids are discussed, as well as some open questions.

  20. The Student Choice Movement.

    ERIC Educational Resources Information Center

    Geis, George L.

    "By 'student choice' we mean a situation in which the behavior (of 'choosing') is not overly determined by the instructional system. That is, the student is presented with a situation in which individual variables...are major determinants of the response emitted..." This definition, found in the first of three sections of this paper, forms the…

  1. Variation, Repetition, and Choice

    ERIC Educational Resources Information Center

    Abreu-Rodrigues, Josele; Lattal, Kennon A.; dos Santos, Cristiano V.; Matos, Ricardo A.

    2005-01-01

    Experiment 1 investigated the controlling properties of variability contingencies on choice between repeated and variable responding. Pigeons were exposed to concurrent-chains schedules with two alternatives. In the REPEAT alternative, reinforcers in the terminal link depended on a single sequence of four responses. In the VARY alternative, a…

  2. What Are Our Choices?

    ERIC Educational Resources Information Center

    Molnar, Alex

    1992-01-01

    Nonpublic school educational choice proposals are largely derived from monetarist economic and social theory and exemplify right-wing privatization goals. The U.S. health care system has plenty of competition among insurers, hospitals, and doctors; but it is the most expensive, least equitable system in the industrial world. The mystical belief…

  3. 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.

  4. Timing in Choice Experiments

    PubMed Central

    Jozefowiez, Jeremie; Cerutti, Daniel T.; Staddon, John E. R.

    2005-01-01

    In Experiment 1, pigeons chose between variable- and fixed-interval schedules. The timer for 1 schedule was reset by a reinforcement on that schedule or on either schedule. In both cases, the pigeons timed reinforcement on each schedule from trial onset. The data further suggest that their behavior reflects 2 independent processes: 1 deciding when a response should be emitted and responsible for the timing of the overall activity, and the other determining what this response should be and responsible for the allocation of behavior between the 2 response keys. Results from Experiment 2, which studied choice between 2 fixed-interval schedules, support those 2 conclusions. These results have implications for the study of operant choice in general. PMID:15839777

  5. Mate choice on leks.

    PubMed

    Balmford, A

    1991-03-01

    In lek-breeding animals, males defend tiny territories clustered into arenas, where females come to mate. Typically, most lek males secure relatively few copulations while a small number are highly successful. Recent studies suggest that the skewed distribution of matings seen at leks may be the result of females using a variety of criteria to select particular mating partners. Nevertheless, the possible benefits to females of mate choice at leks, where males offer neither resources nor paternal care, remain obscure.

  6. Choice and foraging.

    PubMed

    Abarca, N; Fantino, E

    1982-09-01

    In Experiment 1, six naive pigeons were trained on a foraging schedule characterized by different states beginning with a search state in which completion of a fixed-interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule of reinforcement that was offered (either a variable-interval five-second or a variable-interval 20-second). If the subject accepted the schedule, it entered a "handling state" in which the appropriate variable-interval schedule was presented. Completion of the variable-interval schedule produced food. The independent variable was the fixed-interval value in the search state, and the dependent variable was the rate of acceptance of the long variable-interval in the choice state. Experiment 2 was identical except that the search state required completion of a variable-interval, instead of a fixed-interval, schedule. The rate of acceptance of the long variable-interval schedule in both experiments was a direct function of the length of the search state, in accordance with both optimality theory and the delay-reduction hypothesis.

  7. Mate choice turns cognitive.

    PubMed

    Miller, G F; Todd, P M

    1998-05-01

    Evolutionary psychology has revolutionized research on human mate choice and sexual attraction in recent years, combining a rigorous Darwinian framework based on sexual selection theory with a loosely cognitivist orientation to task analysis and mechanism modelling. This hard Darwinian, soft computational approach has been most successful at revealing the adaptive logic behind physical beauty, demonstrating that many sexual cues computed from face and body shape are not arbitrary, but function as reliable indicators of phenotypic and genetic quality. The same approach could be extended from physical to psychological cues if evolutionary psychology built stronger ties with personality psychology, psychometrics and behavioral genetics. A major challenge for mate choice research is to develop more explicit computational models at three levels, specifying: (1) the perceptual adaptations that register sexual cues given sensory input, (2) the judgment adaptations that integrate multiple cues into assessments of overall attractiveness, and (3) the search strategies that people follow in trying to form mutually attracted pairs. We describe both recent efforts and possible extensions in these directions. The resulting confluence between evolutionary principles, cognitive models and game-theoretic insights can put mate choice research at the vanguard of an emerging `evolutionary cognitive science' more concerned with domain-specific mental adaptations than with domain-general intelligence. PMID:21227154

  8. Alternative fuels and vehicles choice model

    SciTech Connect

    Greene, D.L.

    1994-10-01

    This report describes the theory and implementation of a model of alternative fuel and vehicle choice (AFVC), designed for use with the US Department of Energy`s Alternative Fuels Trade Model (AFTM). The AFTM is a static equilibrium model of the world supply and demand for liquid fuels, encompassing resource production, conversion processes, transportation, and consumption. The AFTM also includes fuel-switching behavior by incorporating multinomial logit-type equations for choice of alternative fuel vehicles and alternative fuels. This allows the model to solve for market shares of vehicles and fuels, as well as for fuel prices and quantities. The AFVC model includes fuel-flexible, bi-fuel, and dedicated fuel vehicles. For multi-fuel vehicles, the choice of fuel is subsumed within the vehicle choice framework, resulting in a nested multinomial logit design. The nesting is shown to be required by the different price elasticities of fuel and vehicle choice. A unique feature of the AFVC is that its parameters are derived directly from the characteristics of alternative fuels and vehicle technologies, together with a few key assumptions about consumer behavior. This not only establishes a direct link between assumptions and model predictions, but facilitates sensitivity testing, as well. The implementation of the AFVC model as a spreadsheet is also described.

  9. Occupational Choice and Student Values

    ERIC Educational Resources Information Center

    McSweeney, R. V.

    1973-01-01

    Article attempts to set out a way of measuring determination, the element capable of making students' occupational choice' a reality not just an ideal, by exploration of the part played by the value system in relation to occupational choice. (Author)

  10. School Choice. Trends and Issues.

    ERIC Educational Resources Information Center

    Hadderman, Margaret, Comp.

    This document examines many of the issues surrounding school choice. It summarizes the prevalence of school choice and touches on elements of the debate, such as the dilemma in finding the right balance between individual/family freedom and the interests of the community. In looking at school-choice options, the paper divides them into…

  11. Student Curriculum Choice and Change.

    ERIC Educational Resources Information Center

    Miner, Norris

    This study investigated changes in student curriculum choice at Seminole Junior College (Florida) A code system was developed for 72 curriculum choices (23 in terminal degree areas), grouped into 19 broad clusters. A computerized Student Flow Matrix was then constructed to display the first and second term curriculum choices of 1,391 students who…

  12. 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…

  13. How choice modifies preference: neural correlates of choice justification.

    PubMed

    Qin, Jungang; Kimel, Sasha; Kitayama, Shinobu; Wang, Xiaoying; Yang, Xuedong; Han, Shihui

    2011-03-01

    When making a difficult choice, people often justify the choice by increasing their liking for the chosen object and decreasing their liking for the rejected object. To uncover the neural signatures of choice justification, we used functional magnetic resonance imaging to monitor neural activity when subjects rated their preference for chosen and rejected musical CDs before and after they made their choices. We observed that the trial-by-trial attitude change (i.e., increase of preference for chosen items and decrease of preference for rejected items) was predicted by post-choice activity in the ventral medial prefrontal cortex (MPFC), right temporal-parietal junction, anterior insula, and bilateral cerebellum. Furthermore, individual difference in choice justification (i.e., increased preference for chosen items minus decreased preference for rejected items) was predicted by post-choice neural activity in the dorsal MPFC, left lateral prefrontal cortex, and right precentral cortex positively. In addition, interdependent self-construal was correlated with decreased activity in the ventral MPFC in the post-choice than pre-choice sessions. These findings suggest that both negative arousal/regulation and self-reflection are associated with choice justification. This provides evidence for the self-threat theory of choice justification.

  14. The neural predictors of choice preference in intertemporal choice.

    PubMed

    Liu, Lei; Feng, Tingyong

    2012-02-01

    Intertemporal choice may involve two processing stages: a valuation stage and a choice stage. Decision makers must integrate the various dimensions of an option (e.g., money, time) into a single measure of its subjective value (the valuation stage) and then choose the option that is the most valuable (the choice stage). Although previous studies have implicated that subjective values are represented by a diverse set of brain regions (e.g., vmPFC, VStr, and PCC) in intertemporal choice, it is not yet known which of these regions contain information that directly predicts subsequent choice. To address this question, we measured brain activity using functional MRI while participants performed a simple intertemporal choice task. The results found that participants' decision could be encoded by three specific brain areas (vmPFC, ACC, and PCC) even before they were required to make a choice, while the left posterior insula showed positively active in the choice stage when individuals selected the delayed rewards compared to the immediate rewards. These findings suggest that activation patterns in the vmPFC, ACC, and PCC were able to predict the subsequent choice preference; however, left posterior insula may play an important role for choice preference in the choice stage.

  15. Does the number of choice sets matter? Results from a web survey applying a discrete choice experiment.

    PubMed

    Bech, Mickael; Kjaer, Trine; Lauridsen, Jørgen

    2011-03-01

    Optimising the design of discrete choice experiments (DCE) involves maximising not only the statistical efficiency, but also how the nature and complexity of the experiment itself affects model parameters and variance. The present paper contributes by investigating the impact of the number of DCE choice sets presented to each respondent on response rate, self-reported choice certainty, perceived choice difficulty, willingness-to-pay (WTP) estimates, and response variance. A sample of 1053 respondents was exposed to 5, 9 or 17 choice sets in a DCE eliciting preferences for dental services. Our results showed no differences in response rates and no systematic differences in the respondents' self-reported perception of the uncertainty of their DCE answers. There were some differences in WTP estimates suggesting that estimated preferences are to some extent context-dependent, but no differences in standard deviations for WTP estimates or goodness-of-fit statistics. Respondents exposed to 17 choice sets had somewhat higher response variance compared to those exposed to 5 choice sets, indicating that cognitive burden may increase with the number of choice sets beyond a certain threshold. Overall, our results suggest that respondents are capable of managing multiple choice sets - in this case 17 choice sets - without problems.

  16. Overconfidence and Career Choice.

    PubMed

    Schulz, Jonathan F; Thöni, Christian

    2016-01-01

    People self-assess their relative ability when making career choices. Thus, confidence in their own abilities is likely an important factor for selection into various career paths. In a sample of 711 first-year students we examine whether there are systematic differences in confidence levels across fields of study. We find that our experimental confidence measures significantly vary between fields of study: While students in business related academic disciplines (Political Science, Law, Economics, and Business Administration) exhibit the highest confidence levels, students of Humanities range at the other end of the scale. This may have important implications for subsequent earnings and professions students select themselves in.

  17. Overconfidence and Career Choice.

    PubMed

    Schulz, Jonathan F; Thöni, Christian

    2016-01-01

    People self-assess their relative ability when making career choices. Thus, confidence in their own abilities is likely an important factor for selection into various career paths. In a sample of 711 first-year students we examine whether there are systematic differences in confidence levels across fields of study. We find that our experimental confidence measures significantly vary between fields of study: While students in business related academic disciplines (Political Science, Law, Economics, and Business Administration) exhibit the highest confidence levels, students of Humanities range at the other end of the scale. This may have important implications for subsequent earnings and professions students select themselves in. PMID:26808273

  18. Overconfidence and Career Choice

    PubMed Central

    Schulz, Jonathan F.; Thöni, Christian

    2016-01-01

    People self-assess their relative ability when making career choices. Thus, confidence in their own abilities is likely an important factor for selection into various career paths. In a sample of 711 first-year students we examine whether there are systematic differences in confidence levels across fields of study. We find that our experimental confidence measures significantly vary between fields of study: While students in business related academic disciplines (Political Science, Law, Economics, and Business Administration) exhibit the highest confidence levels, students of Humanities range at the other end of the scale. This may have important implications for subsequent earnings and professions students select themselves in. PMID:26808273

  19. Choice of the regularization parameter for perfusion quantification with MRI

    NASA Astrophysics Data System (ADS)

    Sourbron, S.; Luypaert, R.; Van Schuerbeek, P.; Dujardin, M.; Stadnik, T.

    2004-07-01

    Truncated singular value decomposition (TSVD) is an effective method for the deconvolution of dynamic contrast enhanced (DCE) MRI. Two robust methods for the selection of the truncation threshold on a pixel-by-pixel basis—generalized cross validation (GCV) and the L-curve criterion (LCC)—were optimized and compared to paradigms in the literature. GCV and LCC were found to perform optimally when applied with a smooth version of TSVD, known as standard form Tikhonov regularization (SFTR). The methods lead to improvements in the estimate of the residue function and of its maximum, and converge properly with SNR. The oscillations typically observed in the solution vanish entirely, and perfusion is more accurately estimated at small mean transit times. This results in improved image contrast and increased sensitivity to perfusion abnormalities, at the cost of 1-2 min in calculation time and hyperintense clusters in the image. Preliminary experience with clinical data suggests that the latter problem can be resolved using spatial continuity and/or hybrid thresholding methods. In the simulations GCV and LCC are equivalent in terms of performance, but GCV thresholding is faster.

  20. 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

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

    DOE PAGESBeta

    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

  2. New method for tuning hyperparameter for the total variation norm in the maximum a posteriori ordered subsets expectation maximization reconstruction in SPECT myocardial perfusion imaging

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoxia; Krol, Andrzej; Xu, Yuesheng; Feiglin, David H.

    2011-03-01

    In order to improve the tradeoff between noise and bias, and to improve uniformity of the reconstructed myocardium while preserving spatial resolution in parallel-beam collimator SPECT myocardial perfusion imaging (MPI) we investigated the most advantageous approach to provide reliable estimate of the optimal value of hyperparameter for the Total Variation (TV) norm in the iterative Bayesian Maximum A Posteriori Ordered Subsets Expectation Maximization (MAP-OSEM) one step late tomographic reconstruction with Gibbs prior. Our aim was to find the optimal value of hyperparameter corresponding to the lowest bias at the lowest noise while maximizing uniformity and spatial resolution for the reconstructed myocardium in SPECT MPI. We found that the L-curve method that is by definition a global technique provides good guidance for selection of the optimal value of the hyperparameter. However, for a heterogeneous object such as human thorax the fine-tuning of the hyperparameter's value can be only accomplished by means of a local method such as the proposed bias-noise distance (BND) curve. We established that our BND-curve method provides accurate optimized hyperparameter's value estimation as long as the region of interest volume for which it is defined is sufficiently large and is located sufficiently close to the myocardium.

  3. Context effects on choice.

    PubMed

    Goldshmidt, J N; Lattal, K M; Fantino, E

    1998-11-01

    Four pigeons responded on a concurrent-chains schedule in four experiments that examined whether the effectiveness of a stimulus as a conditioned reinforcer is best described by a global approach, as measured by the average interreinforcement interval, or by a local contextual approach, as measured by the onset of the stimulus preceding the conditioned reinforcer. The interreinforcement interval was manipulated by the inclusion of an intertrial interval, which increased the overall time to reinforcement but did not change the local contingencies on a given trial A global analysis predicted choice for the richer alternative to decrease with the inclusion of an intertrial interval, whereas a local analysis predicted no change in preference. Experiment 1 examined sensitivity to intertrial intervals when each was signaled by the same houselight that operated throughout the session. In Experiment 2, the intertrial interval always was signaled by the stimulus correlated with the richer terminal link. In Experiment 3, the intertrial interval was signaled by the keylights correlated with the initial links and two novel houselights. Experiment 4 provided free food pseudorandomly during the intertrial interval. In all experiments, subjects' preferences were consistent with a local analysis of choice in concurrent chains. These results are discussed in terms of delay-reduction theory, which traditionally has failed to distinguish global and local contexts.

  4. Context effects on choice.

    PubMed Central

    Goldshmidt, J N; Lattal, K M; Fantino, E

    1998-01-01

    Four pigeons responded on a concurrent-chains schedule in four experiments that examined whether the effectiveness of a stimulus as a conditioned reinforcer is best described by a global approach, as measured by the average interreinforcement interval, or by a local contextual approach, as measured by the onset of the stimulus preceding the conditioned reinforcer. The interreinforcement interval was manipulated by the inclusion of an intertrial interval, which increased the overall time to reinforcement but did not change the local contingencies on a given trial A global analysis predicted choice for the richer alternative to decrease with the inclusion of an intertrial interval, whereas a local analysis predicted no change in preference. Experiment 1 examined sensitivity to intertrial intervals when each was signaled by the same houselight that operated throughout the session. In Experiment 2, the intertrial interval always was signaled by the stimulus correlated with the richer terminal link. In Experiment 3, the intertrial interval was signaled by the keylights correlated with the initial links and two novel houselights. Experiment 4 provided free food pseudorandomly during the intertrial interval. In all experiments, subjects' preferences were consistent with a local analysis of choice in concurrent chains. These results are discussed in terms of delay-reduction theory, which traditionally has failed to distinguish global and local contexts. PMID:9821681

  5. Motherhood as a choice.

    PubMed

    Mcfadden, P

    1994-06-01

    The choice of motherhood for women and women's rights have been forbidden in law by men, in religious doctrines by men, and within the medical system by men. Women in poverty have little say in determining whether to have children or not. When choice is exercised for abortion, poor women have unsafe and illegal abortions, which can be life-threatening. Rich women have safer options. Women historically have allowed their rights to be eroded by gender inequality and patriarchal manipulation. The religious right and the Roman Catholic church have been allowed to speak and decide for women. Abortion rights are not about western influences, but about maternal mortality. The right to make choices about one's life is the fundamental premise of the universal rights of all human beings. African governments have signed the UN Convention on elimination of all forms of discrimination against women, but the practice of human rights has not been implemented at the local and family level. Motherhood needs to be demystified. Motherhood is linked with the absence of personhood and bodily integrity. The rhetoric of moral obligations and the rights of the unborn child take precedence over the rights of women. The right of an African woman not to have children is not recognized in most Africa societies. The issue of AIDS creates an even more difficult milieu for women. The interests of the family and the interests of men overwhelm the interests of women to protect themselves. Motherhood is essential to validating one's heterosexuality and gaining stature, and females without a child are marginalized and unrecognized. Women whose babies do not survive are marginalized further than barren women. Men derive power from women's birthing. The terminology of male power is replete with expressions such as "pregnant with promise" and "miscarriage of justice's", no one says "uterus envy." Male psychologists only recognize "penis envy." Men need children for purposes of property, lineage, and

  6. SU-E-J-170: Beyond Single-Cycle 4DCT: Maximum a Posteriori (MAP) Reconstruction-Based Binning-Free Multicycle 4DCT for Lung Radiotherapy

    SciTech Connect

    Cheung, Y; Sawant, A; Hinkle, J; Joshi, S

    2014-06-01

    Purpose: Thoracic motion changes from cycle-to-cycle and day-to-day. Conventional 4DCT does not capture these cycle to cycle variations. We present initial results of a novel 4DCT reconstruction technique based on maximum a posteriori (MAP) reconstruction. The technique uses the same acquisition process (and therefore dose) as a conventional 4DCT in order to create a high spatiotemporal resolution cine CT that captures several breathing cycles. Methods: Raw 4DCT data were acquired from a lung cancer patient. The continuous 4DCT was reconstructed using MAP algorithm which uses the raw, time-stamped CT data to reconstruct images while simultaneously estimating deformation in the subject's anatomy. This framework incorporates physical effects such as hysteresis and is robust to detector noise and irregular breathing patterns. The 4D image is described in terms of a 3D reference image defined at one end of the hysteresis loop, and two deformation vector fields (DVFs) corresponding to inhale motion and exhale motion respectively. The MAP method uses all of the CT projection data and maximizes the log posterior in order to iteratively estimate a timevariant deformation vector field that describes the entire moving and deforming volume. Results: The MAP 4DCT yielded CT-quality images for multiple cycles corresponding to the entire duration of CT acquisition, unlike the conventional 4DCT, which only yielded a single cycle. Variations such as amplitude and frequency changes and baseline shifts were clearly captured by the MAP 4DC Conclusion: We have developed a novel, binning-free, parameterized 4DCT reconstruction technique that can capture cycle-to-cycle variations of respiratory motion. This technique provides an invaluable tool for respiratory motion management research. This work was supported by funding from the National Institutes of Health and VisionRT Ltd. Amit Sawant receives research funding from Varian Medical Systems, Vision RT and Elekta.

  7. Synergistic multi-wavelength remote sensing versus a posteriori combination of retrieved products: Application for the retrieval of atmospheric profiles using MetOp-A

    NASA Astrophysics Data System (ADS)

    Aires, F.; Aznay, O.; Prigent, C.; Paul, M.; Bernardo, F.

    2012-09-01

    In this paper, synergy refers to a process where the use of multiple satellite observations makes the retrieval more precise than the best individual retrieval. Two general strategies can be used in order to use multi-wavelength observations in an inversion scheme. First, the multi-wavelength observations are merged in the input of the retrieval scheme. This means that the various satellite observations are used simultaneously and that their possible interactions can be exploited by the retrieval scheme. Second, each multi-wavelength observations are used independently to retrieve a same geophysical variable and then, these independent retrievals are combined a posteriori using for example a simple weighted averaging. In this paper, it is shown that the first approach provides better synergy results: The retrieval is better suited to optimize the use of all the information available because they are provided to the algorithm simultaneously. In particular, the retrieval process is able, in this case, to exploit the possible interactions between the various input information. The two retrieval approaches are tested and compared using an application for the retrieval of atmospheric profiles and integrated column quantities (temperature, water vapor, and ozone) using MetOp-A observations from IASI, AMSU-A and MHS instruments. Although real satellite observations are considered in this analysis, the results are dependent on the correlation structure in the training data set (i.e. ECMWF analysis) used to calibrate the retrieval algorithm. However, it can be seen that the infrared and microwave observations have a good synergy for the retrieval of atmospheric temperature, water vapor, and for ozone thanks to an indirect synergy.

  8. 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.

  9. 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,…

  10. Hybrid discrete choice models: Gained insights versus increasing effort.

    PubMed

    Mariel, Petr; Meyerhoff, Jürgen

    2016-10-15

    Hybrid choice models expand the standard models in discrete choice modelling by incorporating psychological factors as latent variables. They could therefore provide further insights into choice processes and underlying taste heterogeneity but the costs of estimating these models often significantly increase. This paper aims at comparing the results from a hybrid choice model and a classical random parameter logit. Point of departure for this analysis is whether researchers and practitioners should add hybrid choice models to their suite of models routinely estimated. Our comparison reveals, in line with the few prior studies, that hybrid models gain in efficiency by the inclusion of additional information. The use of one of the two proposed approaches, however, depends on the objective of the analysis. If disentangling preference heterogeneity is most important, hybrid model seems to be preferable. If the focus is on predictive power, a standard random parameter logit model might be the better choice. Finally, we give recommendations for an adequate use of hybrid choice models based on known principles of elementary scientific inference. PMID:27310534

  11. Hybrid discrete choice models: Gained insights versus increasing effort.

    PubMed

    Mariel, Petr; Meyerhoff, Jürgen

    2016-10-15

    Hybrid choice models expand the standard models in discrete choice modelling by incorporating psychological factors as latent variables. They could therefore provide further insights into choice processes and underlying taste heterogeneity but the costs of estimating these models often significantly increase. This paper aims at comparing the results from a hybrid choice model and a classical random parameter logit. Point of departure for this analysis is whether researchers and practitioners should add hybrid choice models to their suite of models routinely estimated. Our comparison reveals, in line with the few prior studies, that hybrid models gain in efficiency by the inclusion of additional information. The use of one of the two proposed approaches, however, depends on the objective of the analysis. If disentangling preference heterogeneity is most important, hybrid model seems to be preferable. If the focus is on predictive power, a standard random parameter logit model might be the better choice. Finally, we give recommendations for an adequate use of hybrid choice models based on known principles of elementary scientific inference.

  12. Understanding Parameter Invariance in Unidimensional IRT Models

    ERIC Educational Resources Information Center

    Rupp, Andre A.; Zumbo, Bruno D.

    2006-01-01

    One theoretical feature that makes item response theory (IRT) models those of choice for many psychometric data analysts is parameter invariance, the equality of item and examinee parameters from different examinee populations or measurement conditions. In this article, using the well-known fact that item and examinee parameters are identical only…

  13. Evidence based contraceptive choices.

    PubMed

    Scott, Alison; Glasier, Anna

    2006-10-01

    People who attend for contraceptive advice have usually formulated an idea of the type of contraceptive that will suit them best. They may wish to use a method that is long, short or medium acting. These are defined as follows: Long-acting method requires renewal no more frequently than every 3 months (e.g. injectable or intrauterine). Short-acting method used daily or with every act of intercourse (e.g. pills, condoms) Medium-acting method requires renewal weekly or monthly (e.g. ring, patch). For men the choice is limited to condoms or vasectomy. Some women do not wish to use hormonal preparations or have an intrauterine device (IUD) or implant inserted. There may also be cultural influences making certain methods of contraception unacceptable. Each of these factors influences the final decision of which method of contraception is decided upon. In addition to taking a full medical and sexual history to identify any risks to the individual's health, which might be increased by a particular contraceptive, time must be spent discussing the options available. It is important to ensure that there is a full understanding of the advantages and disadvantages of each method. The most successful contraceptive method is likely to be the one that the woman (or man) chooses, rather than the one the clinician chooses for them. Access for women to contraception can be improved by having convenient clinic times and service developments such as nurse prescribing and Patient Group Directions.

  14. Addiction: Choice or Compulsion?

    PubMed Central

    Henden, Edmund; Melberg, Hans Olav; Røgeberg, Ole Jørgen

    2013-01-01

    Normative thinking about addiction has traditionally been divided between, on the one hand, a medical model which sees addiction as a disease characterized by compulsive and relapsing drug use over which the addict has little or no control and, on the other, a moral model which sees addiction as a choice characterized by voluntary behavior under the control of the addict. Proponents of the former appeal to evidence showing that regular consumption of drugs causes persistent changes in the brain structures and functions known to be involved in the motivation of behavior. On this evidence, it is often concluded that becoming addicted involves a transition from voluntary, chosen drug use to non-voluntary compulsive drug use. Against this view, proponents of the moral model provide ample evidence that addictive drug use involves voluntary chosen behavior. In this article we argue that although they are right about something, both views are mistaken. We present a third model that neither rules out the view of addictive drug use as compulsive, nor that it involves voluntary chosen behavior. PMID:23966955

  15. A woman's choice.

    PubMed

    Sparrow, Margaret June

    2004-04-01

    Abortion is now the most common gynaecological operation in New Zealand and Australia. Early legal abortion is a safe procedure whether carried out surgically or medically. In contrast, the traditional use of abortifacients has been mostly unscientific, illegal and shrouded in secrecy. Mifepristone as an option for induced abortion has only recently become available in New Zealand and is not yet available in Australia. The reasons for the delay in introducing a significant new abortion technique are political, professional, legal, socioeconomic and commercial. Istar, a not-for-profit company, was formed in New Zealand in 1999 to import mifepristone. The drug was approved for use in New Zealand on 30 August 2001. It was first used in October 2001 in Wellington for mid-trimester abortions and in April 2002 for early medical abortions. Legal ambiguities were clarified in a High Court Judgment on 10 April 2003. The experience with mifepristone raises concerns about the introduction of new drugs for reproductive health care, given the commercial risks associated with their development. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists has a role to play in ensuring that safe abortion services are available for women. Advocates of women's rights in reproductive health care have made a significant impact in the last three decades and the conclusion that abortion must be the woman's choice is strongly supported.

  16. 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…

  17. 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…

  18. 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…

  19. PATERNAL INFLUENCE ON CAREER CHOICE.

    ERIC Educational Resources Information Center

    WERTS, CHARLES E.

    FATHER'S OCCUPATION WAS COMPARED WITH SON'S CAREER CHOICE FOR A SAMPLE OF 76,015 MALE, COLLEGE FRESHMEN. RESULTS INDICATED THAT CERTAIN TYPES OF FATHERS' OCCUPATIONS WERE ASSOCIATED WITH SIMILAR TYPES OF CAREER CHOICES BY SONS. BOYS WHOSE FATHERS WERE IN SCIENTIFIC OCCUPATIONS (ENGINEERS, MILITARY OFFICERS, ARCHITECTS, BIOLOGISTS, CHEMISTS, AND…

  20. School: A Matter of Choice.

    ERIC Educational Resources Information Center

    Organisation for Economic Cooperation and Development, Paris (France). Centre for Educational Research and Innovation.

    Measures to improve parent and student choice of school have recently become an important issue for educational reform in a number of Organisation for Economic Co-operation and Development (OECD) countries. This book summarizes the school-choice experiences of selected OECD countries. The data, collected by the OECD/Centre for Educational Research…

  1. 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…

  2. 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 resources…

  3. 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

  4. 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…

  5. Marriage Enrichment through Choice Awareness.

    ERIC Educational Resources Information Center

    Nelson, Richard C.; Friest, Wendell P.

    1980-01-01

    Choice Awareness is a cognitive-affective-behavioral system that goes beyond both communication training and behavioral bartering approaches to marriage enrichment. Couples explore thoughts, feelings, and actions in their relationships and develop personal power in making choices and in taking responsibility for their own lives. (Author)

  6. School Choice in South Africa

    ERIC Educational Resources Information Center

    Maile, Simeon

    2004-01-01

    In this article, the author investigates the basic elements of choice and markets theory. In recent years, children were moving from rural and township schools to suburban White schools. This trend emerged in the late 1980s and simmered after the demise of apartheid. At face value, school choice appears to be happening merely for the reason of…

  7. School Choice: To What End?

    ERIC Educational Resources Information Center

    Wagner, Tony

    1996-01-01

    Debunks two fantasies: the feasibility of a free-market educational system and the idea that greater choice automatically means better schools. Public education is too labor-intensive and undercapitalized to be profitable. Communities need "skunk works" schools of choice to do research and development and smaller, collaboratively managed schools…

  8. 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 advantage, autonomy, and…

  9. The logistics of choice.

    PubMed

    Killeen, Peter R

    2015-07-01

    The generalized matching law (GML) is reconstructed as a logistic regression equation that privileges no particular value of the sensitivity parameter, a. That value will often approach 1 due to the feedback that drives switching that is intrinsic to most concurrent schedules. A model of that feedback reproduced some features of concurrent data. The GML is a law only in the strained sense that any equation that maps data is a law. The machine under the hood of matching is in all likelihood the very law that was displaced by the Matching Law. It is now time to return the Law of Effect to centrality in our science.

  10. 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

  11. Effort, success, and nonuse determine arm choice.

    PubMed

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

    2015-07-01

    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

  12. 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. PMID:25749702

  13. 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

  14. Hyperbolic value addition and general models of animal choice.

    PubMed

    Mazur, J E

    2001-01-01

    Three mathematical models of choice--the contextual-choice model (R. Grace, 1994), delay-reduction theory (N. Squires & E. Fantino, 1971), and a new model called the hyperbolic value-added model--were compared in their ability to predict the results from a wide variety of experiments with animal subjects. When supplied with 2 or 3 free parameters, all 3 models made fairly accurate predictions for a large set of experiments that used concurrent-chain procedures. One advantage of the hyperbolic value-added model is that it is derived from a simpler model that makes accurate predictions for many experiments using discrete-trial adjusting-delay procedures. Some results favor the hyperbolic value-added model and delay-reduction theory over the contextual-choice model, but more data are needed from choice situations for which the models make distinctly different predictions.

  15. 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. PMID:25521352

  16. 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.

  17. Elipsoid ART/ARTMAP category regions for the choice-by-difference category choice function

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, Georgios C.; Georgiopoulos, Michael

    2002-03-01

    In the recent past category regions have been introduced as new geometrical concepts and provide a visualization tool that facilitates significant insight into the nature of the competition among categories during both the training and performance phase of Fuzzy ART (FA) and Fuzzy ARTMAP (FAM). These regions are defined as the geometric interpretation of the Vigilance Test and the competition of each category with an uncommitted F2-layer node for a specific input pattern (Commitment Test). In this paper we show how the notion of category regions can be naturally extended to Ellipsoid ART (EA) and Ellipsoid ARTMAP (EAM) and focus on the regions' theoretical properties, when considering the Choice-by-Difference category choice function. Based on these properties we state three theoretical results applicable to both EA and EAM. Specifically, if r and a denote the vigilance and the choice parameter respectively, we show that in certain areas of the (a,r) plane the result of EA/EAM training is independent of the specific value of either r or w (parameter of the activation function value for an uncommitted F2-layer node). Finally, we provide a refined upper bound on the size of categories created in EA/EAM during training. All the results are immediately applicable to FA/FAM as well.

  18. Modeling one-choice and two-choice driving tasks

    PubMed Central

    Ratcliff, Roger

    2015-01-01

    An experiment is presented in which subjects were tested on both one-choice and two-choice driving tasks and on non-driving versions of them. Diffusion models for one- and two-choice tasks were successful in extracting model-based measures from the response time and accuracy data. These include measures of the quality of the information from the stimuli that drove the decision process (drift rate in the model), the time taken up by processes outside the decision process and, for the two-choice model, the speed/accuracy decision criteria that subjects set. Drift rates were only marginally different between the driving and non-driving tasks, indicating that nearly the same information was used in the two kinds of tasks. The tasks differed in the time taken up by other processes, reflecting the difference between them in response processing demands. Drift rates were significantly correlated across the two two-choice tasks showing that subjects that performed well on one task also performed well on the other task. Nondecision times were correlated across the two driving tasks, showing common abilities on motor processes across the two tasks. These results show the feasibility of using diffusion modeling to examine decision making in driving and so provide for a theoretical examination of factors that might impair driving, such as extreme aging, distraction, sleep deprivation, and so on. PMID:25944448

  19. 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.

  20. A priori and a posteriori investigations for developing large eddy simulations of multi-species turbulent mixing under high-pressure conditions

    SciTech Connect

    Borghesi, Giulio; Bellan, Josette

    2015-03-15

    , and the filtered species mass fluxes. Improved models were developed based on a scale-similarity approach and were found to perform considerably better than the classical ones. These improved models were also assessed in an a posteriori study. Different combinations of the standard models and the improved ones were tested. At the relatively small Reynolds numbers achievable in DNS and at the relatively small filter widths used here, the standard models for the filtered pressure, the filtered heat flux, and the filtered species fluxes were found to yield accurate results for the morphology of the large-scale structures present in the flow. Analysis of the temporal evolution of several volume-averaged quantities representative of the mixing layer growth, and of the cross-stream variation of homogeneous-plane averages and second-order correlations, as well as of visualizations, indicated that the models performed equivalently for the conditions of the simulations. The expectation is that at the much larger Reynolds numbers and much larger filter widths used in practical applications, the improved models will have much more accurate performance than the standard one.

  1. A bound for the smoothing parameter in certain well-known nonparametric density estimators

    NASA Technical Reports Server (NTRS)

    Terrell, G. R.

    1980-01-01

    Two classes of nonparametric density estimators, the histogram and the kernel estimator, both require a choice of smoothing parameter, or 'window width'. The optimum choice of this parameter is in general very difficult. An upper bound to the choices that depends only on the standard deviation of the distribution is described.

  2. 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…

  3. Developing a concept of choice.

    PubMed

    Kushnir, Tamar

    2012-01-01

    Our adult concept of choice is not a simple idea, but rather a complex set of beliefs about the causes of actions. These beliefs are situation-, individual- and culture-dependent, and are thus likely constructed through social learning. This chapter takes a rational constructivist approach to examining the development of a concept of choice in young children. Initially, infants' combine assumptions of rational agency with their capacity for statistical inference to reason about alternative possibilities for, and constraints on, action. Preschoolers' build on this basic understanding by integrating domain-specific causal knowledge of physical, biological, and psychological possibility into their appraisal of their own and others' ability to choose. However, preschoolers continue to view both psychological and social motivations as constraints on choice--for example, stating that one cannot choose to harm another, or to act against personal desires. It is not until later that children share the adult belief that choice mediates between conflicting motivations for action. The chapter concludes by suggesting avenues for future research--to better characterize conceptual changes in beliefs about choice, and to understand how such beliefs arise from children's everyday experiences. PMID:23205412

  4. Suboptimal choice behavior by pigeons.

    PubMed

    Stagner, Jessica P; Zentall, Thomas R

    2010-06-01

    Contrary to the law of effect and optimal foraging theory, pigeons show suboptimal choice behavior by choosing an alternative that provides 20% reinforcement over another that provides 50% reinforcement. They choose the 20% reinforcement alternative--in which 20% of the time, that choice results in a stimulus that always predicts reinforcement, and 80% of the time, it results in another stimulus that predicts its absence--rather than the 50% reinforcement alternative, which results in one of two stimuli, each of which predicts reinforcement 50% of the time. This choice behavior may be related to suboptimal human monetary gambling behavior, because in both cases, the organism overemphasizes the infrequent occurrence of the winning event and underemphasizes the more frequent occurrence of the losing event.

  5. 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…

  6. 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…

  7. 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…

  8. School Choice in Less Populated Areas.

    ERIC Educational Resources Information Center

    Hammond, Tom; Dennison, Bill

    1995-01-01

    Discusses a parental choice case involving a rural (British) school with a 13+ transfer age to determine parents' use of the open enrollment system, effects of transport policy on exercising parental choice, quality of information provided, and factors influencing choice. Transportation was problematic. Four choice factors stood out: teacher…

  9. Florida CHOICES Counselor's Manual 1983-84.

    ERIC Educational Resources Information Center

    Glenn, Thomas R.; Rogers, Zelda

    This manual for counselors is intended for use with CHOICES, a computer assisted career guidance system. Following a brief introduction to CHOICES, the structure (in chart form) and an overview of the contents of the CHOICES system are given. Chapter 2 focuses on counseling clients, emphasizing the three-step helping process, i.e., preCHOICES, to…

  10. 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…

  11. Coming Around on School Choice.

    ERIC Educational Resources Information Center

    Viteritti, Joseph P.

    2002-01-01

    Asserts that opponent's predictions that school choice would result in mass exodus of students and a disparate impact on public schools have failed to materialize. Argues that disadvantaged students, especially blacks, in inner-city schools are the principal beneficiaries of voucher programs. (Contains 13 references.) (PKP)

  12. School Choice and Ethnic Segregation.

    ERIC Educational Resources Information Center

    Karsten, Sjoerd; Ledoux, Guuske; Roeleveld, Jaap; Felix, Charles; Elshof, Dorothe

    2003-01-01

    Explores how school choice has influenced ethnic segregation in Dutch primary schools. Shows that native Dutch parents are significantly more interested in a match between their social and cultural background and the pupil composition of schools than ethnic minority parents. Both groups of parents generally reject predominately "non-White"…

  13. Choice in P-16 Initiatives

    ERIC Educational Resources Information Center

    Meyer, Rhonda

    2008-01-01

    A system of PK-16 parental choice would look much more like the current situation in early education and in postsecondary education than like the system of K-12 neighborhood schools. The changes required would provide more options for a tailored or customized educational experience for each child than those now offered by the K-12 public school…

  14. Fresh Perspectives on School Choice

    ERIC Educational Resources Information Center

    Ferrero, David J.

    2004-01-01

    School choice advocacy is dominated by perspectives that reflect a tendency to regard public schooling as a private service commodity. In recent years, numerous works of Anglo-American political philosophy, sociology and legal theory have attempted to restore a conception of public schooling as an institution that cultivates civic virtue.…

  15. Accommodations for Multiple Choice Tests

    ERIC Educational Resources Information Center

    Trammell, Jack

    2011-01-01

    Students with learning or learning-related disabilities frequently struggle with multiple choice assessments due to difficulty discriminating between items, filtering out distracters, and framing a mental best answer. This Practice Brief suggests accommodations and strategies that disability service providers can utilize in conjunction with…

  16. Denver Makes a Fairer Choice

    ERIC Educational Resources Information Center

    Teske, Paul; Yettick, Holly; Ely, Todd; Klute, Mary

    2015-01-01

    Denver Public Schools traditional and charter schools combined to create a single system that allowed all students to indicate their school choice preferences, replacing a system of more than 60 different selection processes. The new system also gave families a wealth of information regarding school quality. A study of the new system found it was…

  17. No Easy Road to Choice

    ERIC Educational Resources Information Center

    Robelen, Erik W.

    2008-01-01

    In the new educational landscape of New Orleans--where public school choice is a fundamental element--pounding the pavement to drum up students has become a familiar pursuit. Proponents say a central idea of the education system that has emerged since Hurricane Katrina hit in 2005 is to provide a diverse array of high-quality school options, with…

  18. Factors Influencing College Curriculum Choice

    ERIC Educational Resources Information Center

    Reynolds, Carl L.

    1977-01-01

    A recent study conducted at the University of Illinois on what influences college students to consider the agricultural education curriculum showed that the curriculum choice process is somewhat different for agricultural education majors than for students in the non-agricultural education group. Important influences include vocational agriculture…

  19. Educational Choice and Educational Space

    ERIC Educational Resources Information Center

    Thomson, Kathleen Sonia

    2016-01-01

    This dissertation entitled "Educational choice and educational space" aims to explore the confluence of constructed space and geographic space using a supply-side context for New Zealand's public school system of quasi-open enrollment. In Part I, New Zealand's state and state-integrated school system across four urban areas is analyzed…

  20. Positive Adolescent Choices Training (PACT).

    ERIC Educational Resources Information Center

    Hammond, W. Rodney; And Others

    Positive Adolescent Choices Training (PACT) is a health promotion program providing violence prevention programming targeted at black youth, at high risk for becoming either perpetrators or victims of violence. Conducted by the School of Professional Psychology of Wright State University in Dayton, Ohio, in cooperation with Dayton Public Schools,…

  1. Self-Determination and Choice

    ERIC Educational Resources Information Center

    Wehmeyer, Michael L.; Abery, Brian H.

    2013-01-01

    Promoting self-determination and choice opportunities for people with intellectual and developmental disabilities has become best practice in the field. This article reviews the research and development activities conducted by the authors over the past several decades and provides a synthesis of the knowledge in the field pertaining to efforts to…

  2. A probabilistic, dynamic, and attribute-wise model of intertemporal choice.

    PubMed

    Dai, Junyi; Busemeyer, Jerome R

    2014-08-01

    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 3 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 3 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.

  3. The influence of prior choices on current choice.

    PubMed

    de la Piedad, Xochitl; Field, Douglas; Rachlin, Howard

    2006-01-01

    Three pigeons chose between random-interval (RI) and tandem, continuous-reinforcement, fixed-interval (crf-FI) reinforcement schedules by pecking either of two keys. As long as a pigeon pecked on the RI key, both keys remained available. If a pigeon pecked on the crf-FI key, then the RI key became unavailable and the crf-FI timer began to time out. With this procedure, once the RI key was initially pecked, the prospective value of both alternatives remained constant regardless of time spent pecking on the RI key without reinforcement (RI waiting time). Despite this constancy, the rate at which pigeons switched from the RI to the crf-FI decreased sharply as RI waiting time increased. That is, prior choices influenced current choice-an exercise effect. It is argued that such influence (independent of reinforcement contingencies) may serve as a sunk-cost commitment device in self-control situations. In a second experiment, extinction was programmed if RI waiting time exceeded a certain value. Rate of switching to the crf-FI first decreased and then increased as the extinction point approached, showing sensitivity to both prior choices and reinforcement contingencies. In a third experiment, crf-FI availability was limited to a brief window during the RI waiting time. When constrained in this way, switching occurred at a high rate regardless of when, during the RI waiting time, the crf-FI became available.

  4. Preference reversal in multiattribute choice.

    PubMed

    Tsetsos, Konstantinos; Usher, Marius; Chater, Nick

    2010-10-01

    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 effects, have been explained by a number of theoretical proposals. Yet a major theoretical challenge is capturing all 3 effects simultaneously. We review the range of mechanisms that have been proposed to account for decoy effects and analyze in detail 2 computational models, decision field theory (Roe, Busemeyer, & Townsend, 2001) and leaky competing accumulators (Usher & McClelland, 2004), that aim to combine several such mechanisms into an integrated account. By simulating the models, we examine differences in the ways the decoy effects are predicted. We argue that the LCA framework, which follows on Tversky's relational evaluation with loss aversion (Tversky & Kahneman, 1991), provides a more robust account, suggesting that common mechanisms are involved in both high-level decision making and perceptual choice, for which LCA was originally developed.

  5. Spontaneous prosocial choice by chimpanzees

    PubMed Central

    Horner, Victoria; Carter, J. Devyn; Suchak, Malini; de Waal, Frans B. M.

    2011-01-01

    The study of human and primate altruism faces an evolutionary anomaly: There is ample evidence for altruistic preferences in our own species and growing evidence in monkeys, but one of our closest relatives, the chimpanzee (Pan troglodytes), is viewed as a reluctant altruist, acting only in response to pressure and solicitation. Although chimpanzee prosocial behavior has been reported both in observational captive studies and in the wild, thus far Prosocial Choice Tests have failed to produce evidence. However, methodologies of previous Prosocial Choice Tests may have handicapped the apes unintentionally. Here we present findings of a paradigm in which chimpanzees chose between two differently colored tokens: one “selfish” token resulting in a reward for the actor only (1/0), and the other “prosocial” token rewarding both the actor and a partner (1/1). Seven female chimpanzees, each tested with three different partners, showed a significant bias for the prosocial option. Prosocial choices occurred both in response to solicitation by the partner and spontaneously without solicitation. However, directed requests and pressure by the partner reduced the actor's prosocial tendency. These results draw into question previous conclusions indicating that chimpanzees have a limited sensitivity to the needs of others and behave prosocially only in response to significant prompting. PMID:21825175

  6. Supergranular Parameters

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2016-07-01

    I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.

  7. Choices in health care: the European experience.

    PubMed

    Thomson, Sarah; Dixon, Anna

    2006-07-01

    This paper examines some policies to increase or restrict consumer choice in western European health systems as regards four decisions: choice between public and private insurance; choice of public insurance fund; choice of first contact care provider and choice of hospital. Choice between public and private insurance is limited and arose for historical reasons in Germany. Owing to significant constraints, few people choose the private option. Choice of public insurance fund tends to be exercised by younger and healthier people, the decision to change fund is mainly associated with price and, despite complex risk adjustment mechanisms, it has led to risk selection by funds. Choice of first contact care provider is widespread in Europe. In countries where choice has traditionally been restricted, reforms aim to make services more accessible and convenient to patients. Reforms to restrict direct access to specialists aim to reduce unnecessary and inappropriate care but have been unpopular with the public and professionals. Patients' take up of choice of hospital has been surprisingly low, given their stated willingness to travel. Only where choice is actively supported in the context of long waiting times is take up higher. The objectives, implementation and impact of policies about choice have varied across western Europe. Culture and embedded norms may be significant in determining the extent to which patients exercise choice. PMID:16824264

  8. 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.

  9. 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…

  10. Postcoital Contraception: Student Choices and Effectiveness.

    ERIC Educational Resources Information Center

    Schilling, Lee H.

    1984-01-01

    Information was gathered from college students to observe choice of postcoital contraception (PCC) and the effectiveness of the choice. Results indicate that PCC is an effective second chance to prevent unintended pregnancy. Research methodology is presented. (Author/DF)

  11. Incentive theory: II. Models for choice.

    PubMed

    Killeen, P R

    1982-09-01

    Incentive theory is extended to account for concurrent chained schedules of reinforcement. The basic model consists of additive contributions from the primary and secondary effects of reinforcers, which serve to direct the behavior activated by reinforcement. The activation is proportional to the rate of reinforcement and interacts multiplicatively with the directive effects. The two free parameters are q, the slope of the delay of reinforcement gradient, whose value is constant across many experiments, and b, a bias parameter. The model is shown to provide an excellent description of all results from studies that have varied the terminal-link schedules, and of many of the results from studies that have varied initial-link schedules. The model is extended to diverse modifications of the terminal links, such as varied amount of reinforcement, varied signaling of the terminal-link schedules, and segmentation of the terminal-link schedules. It is demonstrated that incentive theory provides an accurate and integrated account of many of the phenomena of choice.

  12. 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…

  13. A Framework for Choice Remedy Litigation

    ERIC Educational Resources Information Center

    Bolick, Clint

    2008-01-01

    Although school choice proponents have generally been on the offensive in legislative arenas over the past 2 decades, they have played almost constant defense in the judiciary, seeking to prevent courts from undoing school choice programs. Opponents typically wield state constitutional provisions against school choice programs. Properly construed,…

  14. Choice Heats Up. Policy Update Number 2.

    ERIC Educational Resources Information Center

    Amsler, Mary

    This update provides an overview of school-choice models and issues as they were defined in 1992. It describes how intra- and inter-district programs work and the factors that contribute to the effectiveness of a choice plan. Tensions in the choice debate center around the issues of diversity versus commonality, competition versus efficiency, and…

  15. 34 CFR 361.52 - Informed choice.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Informed choice. 361.52 Section 361.52 Education... Informed choice. (a) General provision. The State plan must assure that applicants and eligible individuals... applicants and eligible individuals in exercising informed choice throughout the rehabilitation...

  16. Choice Awareness: A Systematic, Eclectic Counseling Theory.

    ERIC Educational Resources Information Center

    Nelson, Richard C.

    This book presents choice awareness as an eclectic counseling theory. The five choice principles of CREST are listed as Caring, Ruling, Enjoying, Sorrowing, and Thinking/Working. The focus is on providing the counselor with a direct and concise approach which will enable clients to make more effective choices and to exercise more responsibility in…

  17. 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…

  18. The Challenge of Diversity and Choice

    ERIC Educational Resources Information Center

    Glenn, Charles

    2005-01-01

    Schools of equal educational quality need not be identical, and the recent trend toward increased choice and diversity in American schooling has if anything made the system more equitable for children who previously had no choice but to attend poorly performing schools. That is not to say that all forms of school choice are good public policy:…

  19. 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…

  20. 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…

  1. Pricing effects on food choices.

    PubMed

    French, Simone A

    2003-03-01

    Individual dietary choices are primarily influenced by such considerations as taste, cost, convenience and nutritional value of foods. The current obesity epidemic has been linked to excessive consumption of added sugars and fat, as well as to sedentary lifestyles. Fat and sugar provide dietary energy at very low cost. Food pricing and marketing practices are therefore an essential component of the eating environment. Recent studies have applied economic theories to changing dietary behavior. Price reduction strategies promote the choice of targeted foods by lowering their cost relative to alternative food choices. Two community-based intervention studies used price reductions to promote the increased purchase of targeted foods. The first study examined lower prices and point-of-purchase promotion on sales of lower fat vending machine snacks in 12 work sites and 12 secondary schools. Price reductions of 10%, 25% and 50% on lower fat snacks resulted in an increase in sales of 9%, 39% and 93%, respectively, compared with usual price conditions. The second study examined the impact of a 50% price reduction on fresh fruit and baby carrots in two secondary school cafeterias. Compared with usual price conditions, price reductions resulted in a four-fold increase in fresh fruit sales and a two-fold increase in baby carrot sales. Both studies demonstrate that price reductions are an effective strategy to increase the purchase of more healthful foods in community-based settings such as work sites and schools. Results were generalizable across various food types and populations. Reducing prices on healthful foods is a public health strategy that should be implemented through policy initiatives and industry collaborations. PMID:12612165

  2. TAFV Alternative Fuels and Vehicles Choice Model Documentation

    SciTech Connect

    Greene, D.L.

    2001-07-27

    A model for predicting choice of alternative fuel and among alternative vehicle technologies for light-duty motor vehicles is derived. The nested multinomial logit (NML) mathematical framework is used. Calibration of the model is based on information in the existing literature and deduction based on assuming a small number of key parameters, such as the value of time and discount rates. A spreadsheet model has been developed for calibration and preliminary testing of the model.

  3. Anaesthetics: career choices and experiences.

    PubMed

    Parkhouse, J; Ellin, D J

    1990-01-01

    At the pre-registration stage, about 4% of doctors who qualified in 1974 and about 5% of 1977 qualifiers gave anaesthetics as a first choice of career. Over the few years after qualifying, both cohorts showed a net gain in career preferences for anaesthetics. The progress of those choosing anaesthetics is described, and also the career paths of those becoming senior registrars in the specialty. Postgraduate qualifications, non-anaesthetic and overseas experience are analysed. Discussion deals with breadth of experience, women doctors and manpower implications. PMID:2300005

  4. 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

  5. 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…

  6. Midlife Career Choices: How Are They Different from Other Career Choices?

    ERIC Educational Resources Information Center

    Zemon, Candy (Bogar)

    2002-01-01

    Presents a personal narrative of a midlife decision point and the choice that one librarian made regarding a career change. Topics include initial career choice; lateral and interim career choices; differences in midlife career choices; and continuing along a similar career path versus starting over in something very different. (LRW)

  7. Cultural neuroeconomics of intertemporal choice.

    PubMed

    Takahashi, Taiki; Hadzibeganovic, Tarik; Cannas, Sergio A; Makino, Takaki; Fukui, Hiroki; Kitayama, Shinobu

    2009-01-01

    According to theories of cultural neuroscience, Westerners and Easterners may have distinct styles of cognition (e.g., different allocation of attention). Previous research has shown that Westerners and Easterners tend to utilize analytical and holistic cognitive styles, respectively. On the other hand, little is known regarding the cultural differences in neuroeconomic behavior. For instance, economic decisions may be affected by cultural differences in neurocomputational processing underlying attention; however, this area of neuroeconomics has been largely understudied. In the present paper, we attempt to bridge this gap by considering the links between the theory of cultural neuroscience and neuroeconomic theory of the role of attention in intertemporal choice. We predict that (i) Westerners are more impulsive and inconsistent in intertemporal choice in comparison to Easterners, and (ii) Westerners more steeply discount delayed monetary losses than Easterners. We examine these predictions by utilizing a novel temporal discounting model based on Tsallis' statistics (i.e. a q-exponential model). Our preliminary analysis of temporal discounting of gains and losses by Americans and Japanese confirmed the predictions from the cultural neuroeconomic theory. Future study directions, employing computational modeling via neural networks, are outlined and discussed.

  8. Social determinants of food choice.

    PubMed

    Shepherd, R

    1999-11-01

    Food choice is influenced by a large number of factors, including social and cultural factors. One method for trying to understand the impact of these factors is through the study of attitudes. Research is described which utilizes social psychological attitude models of attitude-behaviour relationships, in particular the Theory of Planned Behaviour. This approach has shown good prediction of behaviour, but there are a number of possible extensions to this basic model which might improve its utility. One such extension is the inclusion of measures of moral concern, which have been found to be important both for the choice of genetically-modified foods and also for foods to be eaten by others. It has been found to be difficult to effect dietary change, and there are a number of insights from social psychology which might address this difficulty. One is the phenomenon of optimistic bias, where individuals believe themselves to be at less risk from various hazards than the average person. This effect has been demonstrated for nutritional risks, and this might lead individuals to take less note of health education messages. Another concern is that individuals do not always have clear-cut attitudes, but rather can be ambivalent about food and about healthy eating. It is important, therefore, to have measures for this ambivalence, and an understanding of how it might impact on behaviour.

  9. [Choice based on plausible reasons].

    PubMed

    Yamada, Ayumi; Toyama, Midori

    2010-12-01

    This study tested the prediction that preferences induced by hidden factors would be justified and even accelerated by other factors that seem to be plausible determinants as causes but, in fact, do not have any influence on the preferences. Participants were repeatedly exposed to a variety of product logos of detergents and then asked to choose one from a pair of detergents with different logos. For half of the participants, information on product quality was available at choice; for the other half, only logos were available. The participants showed a tendency to prefer detergents with the logos that were more frequently exhibited, and this tendency was stronger when information was available about the product quality. The participants seemed to believe that they based their decisions on the relative superiority of quality between the pairs as well as their logos. Provided with convincing, but incorrect, reasons to make a choice, the participants were encouraged to select the detergents whose attractiveness had actually been manipulated by exposing the participants to their logos. PMID:21226288

  10. Multiplexed modulation of behavioral choice

    PubMed Central

    Palmer, Chris R.; Barnett, Megan N.; Copado, Saul; Gardezy, Fred; Kristan, William B.

    2014-01-01

    Stimuli in the environment, as well as internal states, influence behavioral choice. Of course, animals are often exposed to multiple external and internal factors simultaneously, which makes the ultimate determinants of behavior quite complex. We observed the behavioral responses of European leeches, Hirudo verbana, as we varied one external factor (surrounding water depth) with either another external factor (location of tactile stimulation along the body) or an internal factor (body distention following feeding). Stimulus location proved to be the primary indicator of behavioral response. In general, anterior stimulation produced shortening behavior, midbody stimulation produced local bending, and posterior stimulation usually produced either swimming or crawling but sometimes a hybrid of the two. By producing a systematically measured map of behavioral responses to body stimulation, we found wide areas of overlap between behaviors. When we varied the surrounding water depth, this map changed significantly, and a new feature – rotation of the body along its long axis prior to swimming – appeared. We found additional interactions between water depth and time since last feeding. A large blood meal initially made the animals crawl more and swim less, an effect that was attenuated as water depth increased. The behavioral map returned to its pre-feeding form after approximately 3 weeks as the leeches digested their blood meal. In summary, we found multiplexed impacts on behavioral choice, with the map of responses to tactile stimulation modified by water depth, which itself modulated the impact that feeding had on the decision to swim or crawl. PMID:24902753

  11. Social determinants of food choice.

    PubMed

    Shepherd, R

    1999-11-01

    Food choice is influenced by a large number of factors, including social and cultural factors. One method for trying to understand the impact of these factors is through the study of attitudes. Research is described which utilizes social psychological attitude models of attitude-behaviour relationships, in particular the Theory of Planned Behaviour. This approach has shown good prediction of behaviour, but there are a number of possible extensions to this basic model which might improve its utility. One such extension is the inclusion of measures of moral concern, which have been found to be important both for the choice of genetically-modified foods and also for foods to be eaten by others. It has been found to be difficult to effect dietary change, and there are a number of insights from social psychology which might address this difficulty. One is the phenomenon of optimistic bias, where individuals believe themselves to be at less risk from various hazards than the average person. This effect has been demonstrated for nutritional risks, and this might lead individuals to take less note of health education messages. Another concern is that individuals do not always have clear-cut attitudes, but rather can be ambivalent about food and about healthy eating. It is important, therefore, to have measures for this ambivalence, and an understanding of how it might impact on behaviour. PMID:10817147

  12. [Choice based on plausible reasons].

    PubMed

    Yamada, Ayumi; Toyama, Midori

    2010-12-01

    This study tested the prediction that preferences induced by hidden factors would be justified and even accelerated by other factors that seem to be plausible determinants as causes but, in fact, do not have any influence on the preferences. Participants were repeatedly exposed to a variety of product logos of detergents and then asked to choose one from a pair of detergents with different logos. For half of the participants, information on product quality was available at choice; for the other half, only logos were available. The participants showed a tendency to prefer detergents with the logos that were more frequently exhibited, and this tendency was stronger when information was available about the product quality. The participants seemed to believe that they based their decisions on the relative superiority of quality between the pairs as well as their logos. Provided with convincing, but incorrect, reasons to make a choice, the participants were encouraged to select the detergents whose attractiveness had actually been manipulated by exposing the participants to their logos.

  13. Estimating insulin sensitivity from glucose levels only: Use of a non-linear mixed effects approach and maximum a posteriori (MAP) estimation.

    PubMed

    Yates, James W T; Watson, Edmund M

    2013-02-01

    Insulin Sensitivity is an important parameter for the management of Diabetes. It can be derived for a particular patient using data derived from some glucose challenge tests using measured glucose and insulin levels at various times. Whilst a useful approach, deriving insulin sensitivities to inform insulin dosing in other settings such as Intensive Care Units can be more challenging - especially as insulin levels have to be assayed in a laboratory, not at the bedside. This paper investigates an approach to measure insulin sensitivity from glucose levels only. Estimates of mean and between individual parameter variances are used to derive conditional estimates of insulin sensitivity. The method is demonstrated to perform reasonably well, with conditional estimates comparing well with estimates derived from insulin data as well. PMID:22244505

  14. Estimating insulin sensitivity from glucose levels only: Use of a non-linear mixed effects approach and maximum a posteriori (MAP) estimation.

    PubMed

    Yates, James W T; Watson, Edmund M

    2013-02-01

    Insulin Sensitivity is an important parameter for the management of Diabetes. It can be derived for a particular patient using data derived from some glucose challenge tests using measured glucose and insulin levels at various times. Whilst a useful approach, deriving insulin sensitivities to inform insulin dosing in other settings such as Intensive Care Units can be more challenging - especially as insulin levels have to be assayed in a laboratory, not at the bedside. This paper investigates an approach to measure insulin sensitivity from glucose levels only. Estimates of mean and between individual parameter variances are used to derive conditional estimates of insulin sensitivity. The method is demonstrated to perform reasonably well, with conditional estimates comparing well with estimates derived from insulin data as well.

  15. Embedding parameters for Quantum Annealing

    NASA Astrophysics Data System (ADS)

    Venturelli, Davide

    Many optimization problems are defined on highly connected graphs and many interesting physical spin-glass systems are featuring long-range interactions. One method to solve for the optimum/ground state is quantum annealing (QA). Most architectures for QA devices, manufactured or proposed, are based on optimizing Hamiltonians having spins connected in a non-complete graph, with nodes with a small maximum degree, compared to the requirements. To overcome this limitation 'embedding' is employed: the native graph is 'tiled' with ferromagnetic chains of spins that now are meant to represent the logical binary variables. While it is known how the strength of the ferromagnetic bonds can ensure that the classical Ising ground state of the embedded system can be univocally mapped to the ground state of the original system, there is very little study on the impact of these parameters on QA. Programmers have taken conservative choices for the parameters and the common practices can be improved. Starting from the physics of connected ferromagnetic Ising chains, we will review several parameter choices and discuss previous and new results obtained on the D-Wave 2X machine, on carefully designed problems that allow to isolate and evaluate the role of connectivity in embedded systems.

  16. 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.

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

    SciTech Connect

    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 subsequent 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.

  18. A Simplified Model of Choice Behavior under Uncertainty.

    PubMed

    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

  19. 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

  20. A Simplified Model of Choice Behavior under Uncertainty.

    PubMed

    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.

  1. Parameters of technological growth.

    PubMed

    Starr, C; Rudman, R

    1973-10-26

    The key parameters to technological growth have been identified as societal resources and societal expectations. Both of these are evident functions of technology, and their combined effects can be expected to continue technology's historical exponential growth. This growth pattern would be substantially altered only if we assume that knowledge is bounded or if society makes a conscious decision to stop the flow of resources into the production of new technological options. Although such conscious selection among individual technical fields is to be expected, it is very unlikely to apply to the totality of technology since, as society grows more complex it continuously creates new needs (priority factor), which in turn provide new opportunities for the application of technological options (payoff factor). The analysis also clearly emphasizes the important role which awareness of new technologies plays in forming societal expectations. These considerations indicate that the technological component of the world simulation model proposed by Meadows et al. (1) and Forrester (2) is best represented by an exponential growth function. The importance of this has been shown by Boyd (3) (Fig. 1), whose "technological optimist" curve has slightly less than exponential growth. Private comnmunication with Boyd indicates that an exponential assumption would reduce the time for equilibrium by several decades. Boyd also indicated that in his modification of the world dynamics model, an exponential technological growth would eventually dominate all other parameters in determining the long-term approach to a steady state. It is evident that the behavior of any world system model is very sensitive to the growth and interaction assumptions for its principal parameters. Thus, model studies should not be easily presumed to represent reality. The one conclusion that appears to be valid regardless of approach is the evident merit of reducing population growth. The parameter for quality of

  2. Choice both affects and reflects preferences.

    PubMed

    Coppin, Géraldine; Delplanque, Sylvain; Bernard, Charlène; Cekic, Sezen; Porcherot, Christelle; Cayeux, Isabelle; Sander, David

    2014-01-01

    The free-choice paradigm is a widely used paradigm in psychology. It has been used to show that after a choice between two similarly pleasant stimuli, the pleasantness of the chosen one tends to increase, whereas the pleasantness of the rejected one tends to decrease-a spreading of alternatives. However, the methodological validity of the free-choice paradigm to study choice-induced preference change has recently been seriously questioned [Chen, K. M., & Risen, J. L. (2010). How choice affects and reflects preferences: Revisiting the free-choice paradigm. Journal of Personality and Social Psychology, 99, 573-594. doi:10.1037/a0020217]. According to this criticism, the classically reported spreading of alternatives between the first and second rating sessions cannot be unambiguously interpreted to reflect a true change in preferences and can be observed even for completely static preferences. Here, we used two measurement sequences, a classical Rating 1-choice-Rating 2 sequence and a control Rating 1-Rating 2-choice sequence, to disentangle the spreading of alternatives driven by the effect of choice from the artefactual effect highlighted by Chen and Risen. In two studies using different stimulus material (faces and odours), we find that choice has a robust modulatory impact on preferences for rejected odours, but not for chosen odours and not for faces.

  3. Enabling Predictive Simulation and UQ of Complex Multiphysics PDE Systems by the Development of Goal-Oriented Variational Sensitivity Analysis and a-Posteriori Error Estimation Methods

    SciTech Connect

    Estep, Donald

    2015-11-30

    This project addressed the challenge of predictive computational analysis of strongly coupled, highly nonlinear multiphysics systems characterized by multiple physical phenomena that span a large range of length- and time-scales. Specifically, the project was focused on computational estimation of numerical error and sensitivity analysis of computational solutions with respect to variations in parameters and data. In addition, the project investigated the use of accurate computational estimates to guide efficient adaptive discretization. The project developed, analyzed and evaluated new variational adjoint-based techniques for integration, model, and data error estimation/control and sensitivity analysis, in evolutionary multiphysics multiscale simulations.

  4. 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.

  5. Behavioural social choice: a status report

    PubMed Central

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

    2008-01-01

    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. PMID:19073478

  6. Nuclear position dictates DNA repair pathway choice

    PubMed Central

    Lemaître, Charlène; Grabarz, Anastazja; Tsouroula, Katerina; Andronov, Leonid; Furst, Audrey; Pankotai, Tibor; Heyer, Vincent; Rogier, Mélanie; Attwood, Kathleen M.; Kessler, Pascal; Dellaire, Graham; Klaholz, Bruno; Reina-San-Martin, Bernardo; Soutoglou, Evi

    2014-01-01

    Faithful DNA repair is essential to avoid chromosomal rearrangements and promote genome integrity. Nuclear organization has emerged as a key parameter in the formation of chromosomal translocations, yet little is known as to whether DNA repair can efficiently occur throughout the nucleus and whether it is affected by the location of the lesion. Here, we induce DNA double-strand breaks (DSBs) at different nuclear compartments and follow their fate. We demonstrate that DSBs induced at the nuclear membrane (but not at nuclear pores or nuclear interior) fail to rapidly activate the DNA damage response (DDR) and repair by homologous recombination (HR). Real-time and superresolution imaging reveal that DNA DSBs within lamina-associated domains do not migrate to more permissive environments for HR, like the nuclear pores or the nuclear interior, but instead are repaired in situ by alternative end-joining. Our results are consistent with a model in which nuclear position dictates the choice of DNA repair pathway, thus revealing a new level of regulation in DSB repair controlled by spatial organization of DNA within the nucleus. PMID:25366693

  7. Suboptimal Choice in Pigeons: Stimulus Value Predicts Choice over Frequencies.

    PubMed

    Smith, Aaron P; Bailey, Alexandria R; Chow, Jonathan J; Beckmann, Joshua S; Zentall, Thomas R

    2016-01-01

    Pigeons have shown suboptimal gambling-like behavior when preferring a stimulus that infrequently signals reliable reinforcement over alternatives that provide greater reinforcement overall. As a mechanism for this behavior, recent research proposed that the stimulus value of alternatives with more reliable signals for reinforcement will be preferred relatively independently of their frequencies. The present study tested this hypothesis using a simplified design of a Discriminative alternative that, 50% of the time, led to either a signal for 100% reinforcement or a blackout period indicative of 0% reinforcement against a Nondiscriminative alternative that always led to a signal that predicted 50% reinforcement. Pigeons showed a strong preference for the Discriminative alternative that remained despite reducing the frequency of the signal for reinforcement in subsequent phases to 25% and then 12.5%. In Experiment 2, using the original design of Experiment 1, the stimulus following choice of the Nondiscriminative alternative was increased to 75% and then to 100%. Results showed that preference for the Discriminative alternative decreased only when the signals for reinforcement for the two alternatives predicted the same probability of reinforcement. The ability of several models to predict this behavior are discussed, but the terminal link stimulus value offers the most parsimonious account of this suboptimal behavior. PMID:27441394

  8. Suboptimal Choice in Pigeons: Stimulus Value Predicts Choice over Frequencies

    PubMed Central

    Bailey, Alexandria R.; Chow, Jonathan J.; Beckmann, Joshua S.; Zentall, Thomas R.

    2016-01-01

    Pigeons have shown suboptimal gambling-like behavior when preferring a stimulus that infrequently signals reliable reinforcement over alternatives that provide greater reinforcement overall. As a mechanism for this behavior, recent research proposed that the stimulus value of alternatives with more reliable signals for reinforcement will be preferred relatively independently of their frequencies. The present study tested this hypothesis using a simplified design of a Discriminative alternative that, 50% of the time, led to either a signal for 100% reinforcement or a blackout period indicative of 0% reinforcement against a Nondiscriminative alternative that always led to a signal that predicted 50% reinforcement. Pigeons showed a strong preference for the Discriminative alternative that remained despite reducing the frequency of the signal for reinforcement in subsequent phases to 25% and then 12.5%. In Experiment 2, using the original design of Experiment 1, the stimulus following choice of the Nondiscriminative alternative was increased to 75% and then to 100%. Results showed that preference for the Discriminative alternative decreased only when the signals for reinforcement for the two alternatives predicted the same probability of reinforcement. The ability of several models to predict this behavior are discussed, but the terminal link stimulus value offers the most parsimonious account of this suboptimal behavior. PMID:27441394

  9. Basic and applied research on choice responding.

    PubMed Central

    Fisher, W W; Mazur, J E

    1997-01-01

    Choice responding refers to the manner in which individuals allocate their time or responding among available response options. In this article, we first review basic investigations that have identified and examined variables that influence choice responding, such as response effort and reinforcement rate, immediacy, and quality. We then describe recent bridge and applied studies that illustrate how the results of basic research on choice responding can help to account for human behavior in natural environments and improve clinical assessments and interventions. PMID:9316255

  10. Meiotic drive and evolution of female choice.

    PubMed

    Reinhold, K; Engqvist, L; Misof, B; Kurtz, J

    1999-07-01

    As a special version of the good-genes hypothesis, it was recently proposed that females could benefit from choosing drive-resistant males in a meiotic drive system. Here, we examine with a three-locus, six-allele population genetic model whether female choice for drive resistance can evolve. An allele leading to female preference for drive-resistant males was introduced at low frequency into a population polymorphic for meiotic drive and drive resistance. Our simulations show that female choice of drive-resistant males is disadvantageous when resistance is Y-linked. This disadvantage occurs because, at equilibrium, drive-resistant males have lower reproductive success than drive-susceptible males. Thus, female choice of drive-susceptible males can evolve when resistance is Y-linked. When resistance is autosomal, selection on female choice for drive resistance is less strong and depends on the frequency of choice: female preference of resistant males is favoured when choice is rare and disadvantageous when choice is frequent, leading to a stable equilibrium at a low frequency of the choice allele. Independent of the location of drive resistance alleles, males with the non-driving allele always have above average reproductive success. Female choice is therefore beneficial when choosy females prefer males with the non-driving allele.

  11. Early medical career choices and eventual careers.

    PubMed

    Edwards, C; Lambert, T W; Goldacre, M J; Parkhouse, J

    1997-07-01

    The revised structure of hospital specialist training being introduced in the United Kingdom means that a doctor wanting a career in a hospital specialty will need to be confident that his or her early career choice, made within 3 years of qualification, is realistic. Using data from a longitudinal study of the 1983 cohort of UK medical graduates, the early career choices made by over 2000 doctors were compared with their employment 11 years after qualification. At year 11 65% of the doctors were working within the first choice they had expressed towards the end of their pre-registration year, and 79% were employed in their year 3 first choice. There was, however, important variation within this general picture: lower predictive value was associated with choices made by women; choices for hospital mainstreams rather than for general practice; and choices that were less than definite. The recent drop in popularity of general practice as a career choice of new graduates in the UK, and the steady increase in the proportion of women graduates, mean that the predictive value of the career choices of recent graduates may prove to be lower than that of the 1983 cohort.

  12. Intertemporal choice as discounted value accumulation.

    PubMed

    Rodriguez, Christian A; Turner, Brandon M; McClure, Samuel M

    2014-01-01

    Two separate cognitive processes are involved in choosing between rewards available at different points in time. The first is temporal discounting, which consists of combining information about the size and delay of prospective rewards to represent subjective values. The second involves a comparison of available rewards to enable an eventual choice on the basis of these subjective values. While several mathematical models of temporal discounting have been developed, the reward selection process has been largely unexplored. To address this limitation, we evaluated the applicability of the Linear Ballistic Accumulator (LBA) model as a theory of the selection process in intertemporal choice. The LBA model formalizes the selection process as a sequential sampling algorithm in which information about different choice options is integrated until a decision criterion is reached. We compared several versions of the LBA model to demonstrate that choice outcomes and response times in intertemporal choice are well captured by the LBA process. The relationship between choice outcomes and response times that derives from the LBA model cannot be explained by temporal discounting alone. Moreover, the drift rates that drive evidence accumulation in the best-fitting LBA model are related to independently estimated subjective values derived from various temporal discounting models. These findings provide a quantitative framework for predicting dynamics of choice-related activity during the reward selection process in intertemporal choice and link intertemporal choice to other classes of decisions in which the LBA model has been applied.

  13. 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. PMID:21300414

  14. Meiotic drive and evolution of female choice.

    PubMed Central

    Reinhold, K; Engqvist, L; Misof, B; Kurtz, J

    1999-01-01

    As a special version of the good-genes hypothesis, it was recently proposed that females could benefit from choosing drive-resistant males in a meiotic drive system. Here, we examine with a three-locus, six-allele population genetic model whether female choice for drive resistance can evolve. An allele leading to female preference for drive-resistant males was introduced at low frequency into a population polymorphic for meiotic drive and drive resistance. Our simulations show that female choice of drive-resistant males is disadvantageous when resistance is Y-linked. This disadvantage occurs because, at equilibrium, drive-resistant males have lower reproductive success than drive-susceptible males. Thus, female choice of drive-susceptible males can evolve when resistance is Y-linked. When resistance is autosomal, selection on female choice for drive resistance is less strong and depends on the frequency of choice: female preference of resistant males is favoured when choice is rare and disadvantageous when choice is frequent, leading to a stable equilibrium at a low frequency of the choice allele. Independent of the location of drive resistance alleles, males with the non-driving allele always have above average reproductive success. Female choice is therefore beneficial when choosy females prefer males with the non-driving allele. PMID:10445289

  15. S-SAD phasing of monoclinic histidine kinase from Brucella abortus combining data from multiple crystals and orientations: an example of data-collection strategy and a posteriori analysis of different data combinations.

    PubMed

    Klinke, Sebastián; Foos, Nicolas; Rinaldi, Jimena J; Paris, Gastón; Goldbaum, Fernando A; Legrand, Pierre; Guimarães, Beatriz G; Thompson, Andrew

    2015-07-01

    The histidine kinase (HK) domain belonging to the light-oxygen-voltage histidine kinase (LOV-HK) from Brucella abortus is a member of the HWE family, for which no structural information is available, and has low sequence identity (20%) to the closest HK present in the PDB. The `off-edge' S-SAD method in macromolecular X-ray crystallography was used to solve the structure of the HK domain from LOV-HK at low resolution from crystals in a low-symmetry space group (P21) and with four copies in the asymmetric unit (∼108 kDa). Data were collected both from multiple crystals (diffraction limit varying from 2.90 to 3.25 Å) and from multiple orientations of the same crystal, using the κ-geometry goniostat on SOLEIL beamline PROXIMA 1, to obtain `true redundancy'. Data from three different crystals were combined for structure determination. An optimized HK construct bearing a shorter cloning artifact yielded crystals that diffracted X-rays to 2.51 Å resolution and that were used for final refinement of the model. Moreover, a thorough a posteriori analysis using several different combinations of data sets allowed us to investigate the impact of the data-collection strategy on the success of the structure determination.

  16. Quantification of drug choice with the generalized matching law in rhesus monkeys.

    PubMed

    Koffarnus, Mikhail N; Woods, James H

    2008-03-01

    The generalized matching law provides precise descriptions of choice, but has not been used to characterize choice between different doses of drugs or different classes of drugs. The current study examined rhesus monkeys' drug self-administration choices between identical drug doses, different doses, different drugs (cocaine, remifentanil, and methohexital), and between drug and drug-paired stimuli. The bias parameter of the generalized matching law was used to quantify preference for one reinforcer over another. Choice between identical drug doses yielded undermatching. Choices between 0.3 microg/kg/injection remifentanil and either 0.1 microg/kg/injection remifentanil or saline plus drug-paired stimuli revealed bias for the 0.3 microg/kg/injection dose. Choice was relatively insensitive to differences in random interval schedule value when one reinforcer was replaced with drug-paired stimulus presentations. Bias for 0.3 microg/kg/injection remifentanil over 10 microg/kg/injection cocaine was seen in one subject, and indifference was generally observed between 0.1 microg/kg/injection remifentanil and 56 microg/kg/injection cocaine and between 30 microg/kg/injection cocaine and 320 microg/kg/injection methohexital. These findings suggest the bias parameter may be useful in quantitatively measuring level of preference, which would be an advantage over concurrent FR procedures that often result in exclusive choice. PMID:18422019

  17. Expected utility theory and risky choices with health outcomes.

    PubMed

    Hellinger, F J

    1989-03-01

    Studies of people's attitude towards risk in the health sector often involve a comparison of the desirability of alternative medical treatments. Since the outcome of a medical treatment cannot be known with certainty, patients and physicians must make a choice that involves risk. Each medical treatment may be characterized as a gamble (or risky option) with a set of outcomes and associated probabilities. Expected utility theory (EUT) is the standard method to predict people's choices under uncertainty. The author presents the results of a survey that suggests people are very risk averse towards gambles involving health-related outcomes. The survey also indicates that there is significant variability in the risk attitudes across individuals for any given gamble and that there is significant variability in the risk attitudes of a given individual across gambles. The variability of risk attitudes of a given individual suggests that risk attitudes are not absolute but are functions of the parameters in the gamble. PMID:2927183

  18. Looking time predicts choice but not aesthetic value.

    PubMed

    Isham, Eve A; Geng, Joy J

    2013-01-01

    Although visual fixations are commonly used to index stimulus-driven or internally-determined preference, recent evidence suggests that visual fixations can also be a source of decisional bias that moves selection toward the fixated object. These contrasting results raise the question of whether visual fixations always index comparative processes during choice-based tasks, or whether they might better reflect internal preferences when the decision does not carry any economic or corporeal consequences. In two experiments, participants chose which of two objects were more aesthetically pleasing (Exp.1) or appeared more organic (Exp.2), and provided independent aesthetic ratings of the stimuli. Our results demonstrated that fixation parameters were a better index of choice in both decisional domains than of aesthetic preference. The data support models in which visual fixations are specifically related to the evolution of decision processes even when the decision has no tangible consequences. PMID:23977115

  19. "Having choices is the key".

    PubMed

    Ogunleye, B

    1996-08-01

    When Chief Bisi Ogunleye was appointed Nigeria's Minister of Agriculture, the US-educated daughter of a tribal chief still believed that most Nigerian farmers were men. As she traveled throughout the country fulfilling her role, she met a group of women who wanted to start a palm oil and casaba processing plant but lacked the means to get a start-up loan. Chief Ogunleye's efforts to get officials to issue a loan were ridiculed, so she asked her husband to allow her to donate part of her salary to the women. With the $45 from the chief, the women began business and within 3 months had 6 times the original amount. This money was used to help other 6 other women's groups start businesses. By 1985, these efforts were so successful that the chief resigned her government job and founded the Country Women's Association of Nigeria, which has been successful in helping women because it realizes that the most important key to empowerment is having choices.

  20. Constructive Multiple-Choice Testing System

    ERIC Educational Resources Information Center

    Park, Jooyong

    2010-01-01

    The newly developed computerized Constructive Multiple-choice Testing system is introduced. The system combines short answer (SA) and multiple-choice (MC) formats by asking examinees to respond to the same question twice, first in the SA format, and then in the MC format. This manipulation was employed to collect information about the two…

  1. Factors Influencing Career Choice among Police Recruits

    ERIC Educational Resources Information Center

    Cole, Bryan

    2012-01-01

    This quantitative, non-experimental study examined the career choice factors of 154 (n = 154) police recruits to determine a correlation of age group generation to the five career choice factors presented in the Sibson Reward of Work Model. Law enforcement agencies faced a shortage of viable candidates to fill vacant positions. While extensive…

  2. Integrating Activity Patterns into Destination Choice Models.

    ERIC Educational Resources Information Center

    Fesenmaier, Daniel

    1988-01-01

    Factors affecting decision-making on where to go for recreation, specifically state park choice, were analyzed in a study based on data, collected via a telephone survey, from 452 Oklahoma households. The relative accuracy of various models for predicting individual destination choices were also examined. (IAH)

  3. 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…

  4. Instructional Innovation, School Choice, and Student Achievement

    ERIC Educational Resources Information Center

    Berends, Mark; Penaloza, Roberto V.; Cannata, Marisa; Goldring, Ellen

    2009-01-01

    There is limited empirical research about innovation in various types of schools of choice, although viable choice policies tend to assume clear differentiation amongst schools. Innovation can be conceptualized in many ways and takes place at multiple levels of the school organization. Schools can innovate in terms of the roles and responsibility…

  5. 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…

  6. 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…

  7. 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…

  8. Informed Consumer Choice in Community Rehabilitation Programs

    ERIC Educational Resources Information Center

    Hagen-Foley, Debra L.; Rosenthal, David A.; Thomas, Dale F.

    2005-01-01

    This study investigated consumer and staff member perceptions regarding the extent of consumer choice and participatory planning in community-based rehabilitation programs (CRPs) and the relationship between these elements, satisfaction, and outcomes. Consumers reported moderate to high levels of choice in services and employment goals, and…

  9. Race, Social Background, and School Choice Options

    ERIC Educational Resources Information Center

    Goyette, Kimberly A.

    2008-01-01

    This research contributes to discussions about social inequality in school choices in two ways. First, educational choices include the multitude of options families may consider, including choosing a home in a particular area and home-schooling. Decision-making is considered not at a single point in time, but over children's educational careers.…

  10. Parental Choice in East Harlem Schools.

    ERIC Educational Resources Information Center

    Fliegel, Sy

    Poor students and parents in the East Harlem schools of New York City's Community District 4 should have the same opportunity to obtain the benefits of school choice available to the wealthy, who can afford private and parochial schools. Parental choice can provide the catalyst for educational reform by introducing a market mechanism to the public…

  11. Student Diversity, Choice, and School Improvement.

    ERIC Educational Resources Information Center

    Willie, Charles V.; Edwards, Ralph; Alves, Michael J.

    This book examines research about trends affecting public school diversity, improvement, and choice. It finds that schools with socioeconomically and racially diversified student bodies are more effective learning communities than schools that are poverty-concentrated and racially homogenous; public school choice implemented via the controlled…

  12. Household Mobility, School Choices, and School Outcomes.

    ERIC Educational Resources Information Center

    Bayer, Patrick J.

    This paper summarizes work from a dissertation, the main contribution of which was to develop and estimate a new empirical framework for analyzing the equilibrium outcomes of families' choices for choosing a particular residence. The principal component of the framework is a random-coefficients discrete-choice model of the residential location…

  13. 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…

  14. School Choice for Transnational Parents in Tokyo

    ERIC Educational Resources Information Center

    Velliaris, Donna M.; Willis, Craig R.

    2013-01-01

    School choice is centred on parents deciding where and how their children will be educated, and this issue is similar--to varying degrees--for parents all around the world. Parental school choice is the authority that parents exercise in making decisions about where their children will attend school, and choosing a particular educational pathway…

  15. Evaluation of the Randomized Multiple Choice Format.

    ERIC Educational Resources Information Center

    Harke, Douglas James

    Each physics problem used in evaluating the effectiveness of Randomized Multiple Choice (RMC) tests was stated in the conventional manner and was followed by several multiple choice items corresponding to the steps in a written solution but presented in random order. Students were instructed to prepare a written answer and to use it to answer the…

  16. "Score Choice": A Tempest in a Teapot?

    ERIC Educational Resources Information Center

    Hoover, Eric

    2009-01-01

    A new option that allows students to choose which of their test scores to send to colleges has generated renewed criticism of the College Board. College Board officials tout the option, called Score Choice, as a way to ease test taker anxiety. Some prominent admissions officials have publicly described Score Choice as a sales tactic that will…

  17. Leadership Practices and School Choice. Research Brief

    ERIC Educational Resources Information Center

    Cravens, Xiu; Goldring, Ellen; Penaloza, Roberto V.

    2011-01-01

    As part of a larger study on school choice, researchers at the National Center on School Choice examined variation in leadership practices across school types, relying on a convenience matched sample of schools that included charter, magnet, private, and traditional public schools. A total of 284 schools agreed to participate in the study--116…

  18. Effects of Delegated Choice on Performance.

    ERIC Educational Resources Information Center

    Cosier, Richard A.; Aplin, John C.

    1980-01-01

    There were initial positive effects from delegating choice over the selection of goals. The aspect of the task being delegated appears important. One cannot assume allowing others choice over some aspects of the task will be associated with positive outcomes. (Author)

  19. Vouchers--An Illusion of Choice.

    ERIC Educational Resources Information Center

    Ferguson, Janet M.

    2002-01-01

    Vouchers have been touted as a means to give parents more choice in their child's education, with the rationale that this choice will improve their child's chances of succeeding in school. Studies have produced mixed and inconclusive results. Critics argue that only the more motivated and higher income families will use the vouchers, thus…

  20. A Chronology of Parental Choice in Education.

    ERIC Educational Resources Information Center

    McDonald, Sister Dale

    2001-01-01

    Traces the history of parental rights in education since the landmark case Pierce vs. the Society of Sisters (1925), when the existence of private schools was validated. States that initiatives promoting parental choice include : (1) tax relief/credits; (2) vouchers or scholarships; (3) public school choice; and (4) home schooling. Provides a…

  1. The School Choice Hoax: Fixing America's Schools

    ERIC Educational Resources Information Center

    Corwin, Ronald G.; Schneider, E. Joseph

    2007-01-01

    The federal government is devoting millions of dollars to charter and voucher programs that currently require parents to abandon regular public schools. The goal of the authors of The School Choice Hoax is to expose the misleading hyperbole that has been driving the school choice movement and to show how charter schools can become more effective…

  2. School Choice: What Guides an Adolescent's Decision?

    ERIC Educational Resources Information Center

    Matson, Barbara Smith

    Choice in education gained popularity as a means by which families can become involved in the education of their children. This case study addresses how the interests, needs, and objectives of secondary school students, and their parents as reported by the students, resulted in the choice between two high schools in a suburban district with a…

  3. Voices on Choice: The Education Reform Debate.

    ERIC Educational Resources Information Center

    Billingsley, K. L., Ed.

    This collection presents a sampling of opinions of both proponents and opponents in the school choice debate from a variety of professional perspectives, including academics, bureaucrats, politicians, union leaders, economists, lawyers, parents, and activists. The following essays are included: (1) "School Choice Promotes Educational Excellence in…

  4. Can "Word Choices" Compromise a Woman's Career?

    ERIC Educational Resources Information Center

    Mendoza, Sylvia

    2011-01-01

    A letter of recommendation can catapult a woman into the next phase of the interview process for a particular job--or land her in the slush pile. Word choice in describing this female candidate can make or break her career. Letters of recommendation--especially when a reference's word choice paints a negative, less than stellar picture of the…

  5. 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…

  6. School Choice in Suburbia: The Impact of Choice Policies on the Potential for Suburban Integration

    ERIC Educational Resources Information Center

    Holme, Jennifer Jellison; Frankenberg, Erica; Diem, Sarah; Welton, Anjale D.

    2013-01-01

    The bulk of research on the implementation of school choice policies has focused on how choice has been implemented in urban school systems. As of 2007, however, suburban students comprised more than one fourth (29%) of all students engaging in some form of public school choice in the United States. This article examines the implementation of…

  7. Increasing Choice-Making and Choice Awareness for Students with Intellectual Disability

    ERIC Educational Resources Information Center

    Sparks, Shannon Lynn

    2013-01-01

    A number of studies have suggested that when children with disabilities are presented with choice-making opportunities, they can make choices (Bambara, 2004; Carlson, Luiselli, Slyman, & Markowski, 2008; Dibley & Lim, 1999; Manhertz, 2006). Teaching choice-making to students with intellectual disability is an important skill. Students with…

  8. Choice Making Part I: How Children with Severe Disabilities Make Choices of Preference and Knowledge

    ERIC Educational Resources Information Center

    Van Tubbergen, Marie; Omichinski, Donna; Warschausky, Seth

    2007-01-01

    Communication can be difficult for children with conditions such as cerebral palsy because of speech and physical impairments. For this group of children, choice-making is often limited to choices of personal preferences; however, preferences do not reveal intellectual abilities. Therefore, choice-making should be presented to these children in…

  9. On the CREST: Growing through Effective Choices. A Guide to CHOICE AWARENESS.

    ERIC Educational Resources Information Center

    Nelson, Richard C.

    This book provides a way for individuals to look at how they make choices in their lives, and how they might make more effective choices in the future. The first part of the book provides an introduction to the CREST system. The meaning of CREST is defined in terms of the five basic choices available to human beings: Caring, Ruling, Enjoying,…

  10. Gendered Educational and Occupational Choices: Applying the Eccles et al. Model of Achievement-Related Choices

    ERIC Educational Resources Information Center

    Eccles, Jacquelynne

    2011-01-01

    I summarize a theoretical model of the social, cultural, and psychological influences on achievement-related choices and outline how this model can help us understand gendered educational and occupational choices. I argue that both gender differences and individual differences within each gender in educational and occupational choices are linked…

  11. Prenatal Screening, Reproductive Choice, and Public Health

    PubMed Central

    Wilkinson, Stephen

    2015-01-01

    One widely held view of prenatal screening (PNS) is that its foremost aim is, or should be, to enable reproductive choice; this is the Pure Choice view. The article critiques this position by comparing it with an alternative: Public Health Pluralism. It is argued that there are good reasons to prefer the latter, including the following. (1) Public Health Pluralism does not, as is often supposed, render PNS more vulnerable to eugenics-objections. (2) The Pure Choice view, if followed through to its logical conclusions, may have unpalatable implications, such as extending choice well beyond health screening. (3) Any sensible version of Public Health Pluralism will be capable of taking on board the moral seriousness of abortion and will advocate, where practicable, alternative means of reducing the prevalence of disease and disability. (4) Public Health Pluralism is at least as well-equipped as the Pure Choice model to deal with autonomy and consent issues. PMID:25521971

  12. Prenatal screening, reproductive choice, and public health.

    PubMed

    Wilkinson, Stephen

    2015-01-01

    One widely held view of prenatal screening (PNS) is that its foremost aim is, or should be, to enable reproductive choice; this is the Pure Choice view. The article critiques this position by comparing it with an alternative: Public Health Pluralism. It is argued that there are good reasons to prefer the latter, including the following. (1) Public Health Pluralism does not, as is often supposed, render PNS more vulnerable to eugenics-objections. (2) The Pure Choice view, if followed through to its logical conclusions, may have unpalatable implications, such as extending choice well beyond health screening. (3) Any sensible version of Public Health Pluralism will be capable of taking on board the moral seriousness of abortion and will advocate, where practicable, alternative means of reducing the prevalence of disease and disability. (4) Public Health Pluralism is at least as well-equipped as the Pure Choice model to deal with autonomy and consent issues.

  13. [Adolescence and choice of contraceptive].

    PubMed

    Theunissen, L

    1986-11-01

    The majority of books, studies, and publications on adolescence are written by adults, whose frequent focus on unbridled adolescent sexuality, adolescents in crisis, or immature adolescents does not seem to correspond to the self-image of adolescents. All authors agree that adolescence is the period between childhood and adulthood beginning at puberty, but opinions differ as to the termination of adolescence and entrance into adulthood. The most significant consensus about adolescence is its tendency to become prolonged. The majority of authors regard adolescence as a preparation for adult life and hence as a natural phase necessary and indispensable to human existence. Ethnographic studies of societies that do not acknowledge adolescence demonstrate, however, that it is not a natural phase. It is also evident that comparatively few roles in modern society require lengthy periods of preparation such as adolescence. It is therefore difficult to regard adolescence as a time of preparation for adult life. From a historic perspective, adolescence emerged with the socioeconomic transformations of industrialization. Mechanization and automation excluded numerous types of workers, especially young workers, from the labor force. Adolescence represents marginalization of young people in response to socioeconomic exigencies rather than a period of preparation for a better adult life. The marginalization is internalized in the consciousness of adults and youth alike and in their hierarchical relations. The marginalization of young people is expressed in the domain of sexuality by the fact that, although physiologically mature, adolescents are not viewed as psychologically mature enough to have children. Adolescents have sexual relations at increasingly young ages, but unlike adults they are not permitted by society the choice of having a child. Contraception, an option for adults, becomes obligatory for sexually active adolescents. The refusal of contraception or failure to

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Values influencing neonatal nurses' perceptions and choices.

    PubMed

    Raines, D A

    1994-12-01

    The purpose of this research was to identify the values influencing the nurses' perception and choice of behavior in a hypothetical clinical situation. The theoretical framework was Rokeach's theory on the nature of human values and value systems. A descriptive study using a mailed survey was conducted on a random sample of 331 members of the National Association of Neonatal Nurses. Data on individual nurse's values, perception of information, and behavioral choices were collected with an investigator-developed questionnaire consisting of a values scale, and an information scale and choice alternatives related to three hypothetical vignettes: a low-birthweight infant, an infant with chromosomal anomalies, and a chronically ill infant. Results of this study indicate that nurses identified a hierarchy of values related to their practice. Information related to infant characteristics was consistently most important; however, in uncertain situations, rules or external protocols had an increased influence on the behavioral choice process. The behavioral choice option with the greatest agreement was different for each situation. A consistently negative correlation between the options within each vignette indicates that nurses have clearly defined choice preferences. Model testing revealed a consistent relationship across the three vignettes between the variable being just and protocol, doing right and infant characteristics, and infant characteristics and the choice options (p < .05).

  19. A priori and a posteriori dietary patterns at the age of 1 year and body composition at the age of 6 years: the Generation R Study.

    PubMed

    Voortman, Trudy; Leermakers, Elisabeth T M; Franco, Oscar H; Jaddoe, Vincent W V; Moll, Henriette A; Hofman, Albert; van den Hooven, Edith H; Kiefte-de Jong, Jessica C

    2016-08-01

    Dietary patterns have been linked to obesity in adults, however, not much is known about this association in early childhood. We examined associations of different types of dietary patterns in 1-year-old children with body composition at school age in 2026 children participating in a population-based cohort study. Dietary intake at the age of 1 year was assessed with a food-frequency questionnaire. At the children's age of 6 years we measured their body composition with dual-energy X-ray absorptiometry and we calculated body mass index, fat mass index (FMI), and fat-free mass index (FFMI). Three dietary pattern approaches were used: (1) An a priori-defined diet quality score; (2) dietary patterns based on variation in food intake, derived from principal-component-analysis (PCA); and (3) dietary patterns based on variations in FMI and FFMI, derived with reduced-rank-regression (RRR). Both the a priori-defined diet score and a 'Health-conscious' PCA-pattern were characterized by a high intake of fruit, vegetables, grains, and vegetable oils, and, after adjustment for confounders, children with higher adherence to these patterns had a higher FFMI at 6 years [0.19 SD (95 % CI 0.08;0.30) per SD increase in diet score], but had no different FMI. One of the two RRR-patterns was also positively associated with FFMI and was characterized by intake of whole grains, pasta and rice, and vegetable oils. Our results suggest that different a priori- and a posteriori-derived health-conscious dietary patterns in early childhood are associated with a higher fat-free mass, but not with fat mass, in later childhood. PMID:27384175

  20. Career choices among medical students in Bangladesh

    PubMed Central

    Ahmed, SM Moslehuddin; Majumdar, Md Anwarul Azim; Karim, Rezina; Rahman, Sayeeda; Rahman, Nuzhat

    2011-01-01

    Introduction Information regarding career choices of medical students is important to plan human resources for health, design need-based educational programs, and ensure equitable and quality health care services in a country. Aim The aim of the study is to identify career choices, nature of career, intended practice locations, and reasons for career choices of Bangladesh medical students. Method First-, third-, and fifth-year students of Bangladesh Medical College and Uttara Adhunik Medical College completed a self-report questionnaire on career choices, nature of career, intended practice locations, and reasons for career choices. The students were requested to choose three long-term choices from the given specialties. Results A total of 132 students responded (46 males and 86 females) and response rate was 75%. The popular choices (first choice) among males and females were medical specialty, surgical specialty, obstetrics and gynecology, and general practice. For first, second, and third choices altogether, male students chose surgical specialties and female students preferred medical specialties. The leading reasons for selecting a specialty were personal interest and wide job opportunity. More than 67% of respondents wanted to join private services and about 90% chose major cities as practice locations. About 43% of respondents expressed willingness to practice medicine in Bangladesh, whereas 51% of total respondents wanted to practice abroad. Discussion Majority of students intended to specialize in established clinical specialties and subsequently practice in major cities, and more than half wanted to immigrate to other countries. Basic medical subjects and service-oriented (lifestyle-related) and preventive/social medical specialties were found to be less attractive. If this pattern continues, Bangladesh will suffer a chronic shortage of health personnel in certain specialties and in rural areas. Conclusions Reorientation of health care and medical

  1. 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.

  2. The costs of choice in sexual selection.

    PubMed

    Pomiankowski, A

    1987-09-21

    In Fisher's model of sexual selection female mating preferences are not subject to direct selection but evolve purely because they are genetically correlated with the favoured male trait. But when female choice is costly relative to random mating, for example in energy, time or predation risks, the evolution of female mating preference is subject also to direct selection. With costly female choice the set or line of equilibria found in models of Fisher's process no longer exists. On the line the male trait is under zero net selection, and there is no advantage for a female choosing a male with a more exaggerated character. Therefore any cost to choice causes choosiness to decline. In turn this lowers the strength of sexual selection and the male trait declines as well. So when Fisher's process is the sole force of sexual selection and female choice is costly, only transitory increases in female choice and the preferred male trait are possible. It has often been claimed that exaggerated male characters act as markers or revealers of the genetic quality of potential mates. If females choose their mates using traits that correlate with heritable viability differences then stable exaggeration of both female choice and the preferred male character is possible, even when female choice is costly. The offspring of choosy females have not only a Fisherian reproductive advantage but also greater viability. This suggests that in species with exaggerated male ornamentation, in which female choice is costly, it is likely that female mate choice will be for traits that correlate with male genetic quality. PMID:3431135

  3. Linear-Nonlinear-Poisson models of primate choice dynamics.

    PubMed

    Corrado, Greg S; Sugrue, Leo P; Seung, H Sebastian; Newsome, William T

    2005-11-01

    The equilibrium phenomenon of matching behavior traditionally has been studied in stationary environments. Here we attempt to uncover the local mechanism of choice that gives rise to matching by studying behavior in a highly dynamic foraging environment. In our experiments, 2 rhesus monkeys (Macacca mulatta) foraged for juice rewards by making eye movements to one of two colored icons presented on a computer monitor, each rewarded on dynamic variable-interval schedules. Using a generalization of Wiener kernel analysis, we recover a compact mechanistic description of the impact of past reward on future choice in the form of a Linear-Nonlinear-Poisson model. We validate this model through rigorous predictive and generative testing. Compared to our earlier work with this same data set, this model proves to be a better description of choice behavior and is more tightly correlated with putative neural value signals. Refinements over previous models include hyperbolic (as opposed to exponential) temporal discounting of past rewards, and differential (as opposed to fractional) comparisons of option value. Through numerical simulation we find that within this class of strategies, the model parameters employed by animals are very close to those that maximize reward harvesting efficiency.

  4. Implications of Visual Attention Phenomena for Models of Preferential Choice

    PubMed Central

    2016-01-01

    We use computational modeling to examine the ability of evidence accumulation models to produce the reaction time (RT) distributions and attentional biases found in behavioral and eye-tracking research. We focus on simulating RTs and attention in binary choice with particular emphasis on whether different models can predict the late onset bias (LOB), commonly found in eye movements during choice (sometimes called the gaze cascade). The first finding is that this bias is predicted by models even when attention is entirely random and independent of the choice process. This shows that the LOB is not evidence of a feedback loop between evidence accumulation and attention. Second, we examine models with a relative evidence decision rule and an absolute evidence rule. In the relative models a decision is made once the difference in evidence accumulated for 2 items reaches a threshold. In the absolute models, a decision is made once 1 item accumulates a certain amount of evidence, independently of how much is accumulated for a competitor. Our core result is simple—the existence of the late onset gaze bias to the option ultimately chosen, together with a positively skewed RT distribution means that the stopping rule must be relative not absolute. A large scale grid search of parameter space shows that absolute threshold models struggle to predict these phenomena even when incorporating evidence decay and assumptions of either mutual inhibition or feedforward inhibition. PMID:27774490

  5. School Choice, School Quality and Postsecondary Attainment

    PubMed Central

    Deming, David J.; Hastings, Justine S.; Kane, Thomas J.; Staiger, Douglas O.

    2015-01-01

    We study the impact of a public school choice lottery in Charlotte-Mecklenburg schools on college enrollment and degree completion. We find a significant overall increase in college attainment among lottery winners who attend their first choice school. Using rich administrative data on peers, teachers, course offerings and other inputs, we show that the impacts of choice are strongly predicted by gains on several measures of school quality. Gains in attainment are concentrated among girls. Girls respond to attending a better school with higher grades and increases in college-preparatory course-taking, while boys do not. PMID:27244675

  6. Pro-choice: a new militancy.

    PubMed

    Davis, S E

    1989-01-01

    Davis, a pro-choice advocate, describes the reactions of the abortion rights movement to the U.S. Supreme Court's opinion in the 1989 Webster v. Reproductive Health Services case. Viewing the decision that allows individual states to set some restrictions on abortion as a threat to women's reproductive rights, pro-choice advocates have responded "with a new sense of defiance and commitment." Davis describes the demonstrations, sit-ins, and coalitions that give evidence of the new activism of the pro-choice movement.

  7. Theory and method in the quantitative analysis of "impulsive choice" behaviour: implications for psychopharmacology.

    PubMed

    Ho, M Y; Mobini, S; Chiang, T J; Bradshaw, C M; Szabadi, E

    1999-10-01

    Impulsive choice refers to the selection of small immediate gains in preference to larger delayed gains, or the selection of large delayed penalties in preference to smaller immediate penalties. Current theoretical interpretations of impulsive choice are reviewed, and a synthesis of these ideas, the "multiplicative hyperbolic model of choice", is presented. The model assumes that the value of a positive reinforcer increases as a hyperbolic function of its size, and decreases as a hyperbolic function of its delay and the odds against its occurrence. Each hyperbolic function contains a single discounting parameter which quantifies the organism's sensitivity to the variable in question. The hyperbolic discounting functions combine multiplicatively to determine the overall value of the reinforcer. Equivalent functions are postulated to govern the (negative) value of aversive events, the net value of an outcome reflecting the algebraic sum of the positive and negative values. The model gives rise to a quantitative methodology for studying impulsive choice, based on a family of linear indifference (null) equations, which describe performance under conditions of indifference, when the values of the reinforcers are assumed to be equal. This methodology may be used to identify individual differences in sensitivity to the magnitude, delay and probability of reinforcement. The methodology is also suitable for the quantitative evaluation of the effects of some pharmacological interventions on discounting parameters. Recent psychopharmacological studies of impulsive choice are reviewed, and the utility of indifference equations for extending this work, and developing a quantitative psychopharmacology of impulsive choice is discussed.

  8. Refusing The Choice: Balancing Life and Work

    NASA Astrophysics Data System (ADS)

    Brooks, J.

    2012-12-01

    The Choice The intellect of man is forced to choose perfection of the life, or of the work, And if it take the second must refuse A heavenly mansion, raging in the dark. When all that story's finished, what's the news? In luck or out the toil has left its mark: That old perplexity an empty purse, Or the day's vanity, the night's remorse. William Butler Yeats William Yeats put forward The Choice that I feel too many scientists feel they must make. Too often, many choose to leave science. How do we refuse this choice and find balance between life and our careers? While I don't know the answer, I will share choices that have lead to not perfection but satisfaction in science careers and lives. The role of mentors, supportive spouses, the luck of the job, and flexibility in research directions have all contributed to being able to refuse to choose.

  9. The Ecological Classroom: Choices and Consequences.

    ERIC Educational Resources Information Center

    Cookman, Ed

    1993-01-01

    Presents two interdisciplinary lesson plans that explore options in energy production and conservation. Students study (1) the implications of power production and resources choices, and (2) producing and conserving electric power. (MCO)

  10. Irrational choice and the value of information

    PubMed Central

    Vasconcelos, Marco; Monteiro, Tiago; Kacelnik, Alex

    2015-01-01

    Irrational decision making in humans and other species challenges the use of optimality in behavioural biology. Here we show that such observations are in fact powerful tools to understand the adaptive significance of behavioural mechanisms. We presented starlings choices between probabilistic alternatives, receiving or not information about forthcoming, delayed outcomes after their choices. Subjects could not use this information to alter the outcomes. Paradoxically, outcome information induced loss-causing preference for the lower probability option. The effect depended on time under uncertainty: information given just after each choice caused strong preference for lower probability, but information just before the outcome did not. A foraging analysis shows that these preferences would maximize gains if post-choice information were usable, as when predators abandon a chase when sure of the prey escaping. Our study illustrates how experimentally induced irrational behaviour supports rather than weakens the evolutionary optimality approach to animal behaviour. PMID:26350951

  11. Strategy application, observability, and the choice combinator.

    SciTech Connect

    Winter, Victor Lono

    2004-03-01

    In many strategic systems, the choice combinator provides a powerful mechanism for controlling the application of rules and strategies to terms. The ability of the choice combinator to exercise control over rewriting is based on the premise that the success and failure of strategy application can be observed. In this paper we present a higher-order strategic framework with the ability to dynamically construct strategies containing the choice combinator. To this framework, a combinator called hide is introduced that prevents the successful application of a strategy from being observed by the choice combinator. We then explore the impact of this new combinator on a real-world problem involving a restricted implementation of the Java Virtual Machine.

  12. Determining camera parameters for round glassware measurements

    NASA Astrophysics Data System (ADS)

    Baldner, F. O.; Costa, P. B.; Gomes, J. F. S.; Filho, D. M. E. S.; Leta, F. R.

    2015-01-01

    Nowadays there are many types of accessible cameras, including digital single lens reflex ones. Although these cameras are not usually employed in machine vision applications, they can be an interesting choice. However, these cameras have many available parameters to be chosen by the user and it may be difficult to select the best of these in order to acquire images with the needed metrological quality. This paper proposes a methodology to select a set of parameters that will supply a machine vision system with the needed quality image, considering the measurement required of a laboratory glassware.

  13. 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)

  14. Timing and choice in concurrent chains.

    PubMed

    Grace, R C; Nevin, J A

    1999-04-01

    To investigate the role of timing processes in choice, we used a new procedure that provided simultaneous measures of ongoing choice and timing behavior. Pigeons responded in a peak procedure in which the delays to reinforcement signaled by red and green center-key stimuli were 10 and 20, or 20 and 40 s. After 25 sessions of training, the peak procedure was embedded within concurrent chains: The inter-trial interval was replaced by a choice phase in which the two side keys were illuminated white; responses to the left and right keys occasionally changed the center-key to red or green, respectively; and the terminal links signaled by the center-key stimuli were identical to the trials of the peak procedure. The temporal control of responding on no-food trials was the same regardless of whether the no-food trials occurred in the peak procedure or as the terminal links of concurrent chains. After an intervening condition with the peak procedure in which the delay for the 10 s stimulus was changed to 40 s (or vice versa), the pigeons were returned to concurrent chains. Choice responding did not reflect the changed delay, despite the fact that the pigeons timed the delays in both terminal links accurately as indexed by responding on no-food trials. This result challenges current accounts of choice based on timing processes, such as scalar expectancy theory, which assume that choice responding is mediated by a representation of terminal link delays to reinforcement. Apparently, pigeons' choice and timing behavior in a single session can be controlled by temporal information from different temporal epochs.

  15. Partner Choice in Raven (Corvus corax) Cooperation.

    PubMed

    Asakawa-Haas, Kenji; Schiestl, Martina; Bugnyar, Thomas; Massen, Jorg J M

    2016-01-01

    Although social animals frequently make decisions about when or with whom to cooperate, little is known about the underlying mechanisms of partner choice. Most previous studies compared different dyads' performances, though did not allow an actual choice among partners. We tested eleven ravens, Corvus corax, in triads, giving them first the choice to cooperate with either a highly familiar or a rather unfamiliar partner and, second, with either a friend or a non-friend using a cooperative string-pulling task. In either test, the ravens had a second choice and could cooperate with the other partner, given that this one had not pulled the string in the meantime. We show that during the experiments, these partner ravens indeed learn to wait and inhibit pulling, respectively. Moreover, the results of these two experiments show that ravens' preferences for a specific cooperation partner are not based on familiarity. In contrast, the ravens did show a preference based on relationship quality, as they did choose to cooperate significantly more with friends than with non-friends and they were also more proficient when cooperating with a friend. In order to further identify the proximate mechanism of this preference, we designed an open-choice experiment for the whole group where all birds were free to cooperate on two separate apparatuses. This set-up allowed us to distinguish between preferences for close proximity and preferences to cooperate. The results revealed that friends preferred staying close to each other, but did not necessarily cooperate with one another, suggesting that tolerance of proximity and not relationship quality as a whole may be the driving force behind partner choice in raven cooperation. Consequently, we stress the importance of experiments that allow such titrations and, suggest that these results have important implications for the interpretations of cooperation studies that did not include open partner choice.

  16. 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

  17. Partner Choice in Raven (Corvus corax) Cooperation

    PubMed Central

    Asakawa-Haas, Kenji; Schiestl, Martina; Bugnyar, Thomas; Massen, Jorg J. M.

    2016-01-01

    Although social animals frequently make decisions about when or with whom to cooperate, little is known about the underlying mechanisms of partner choice. Most previous studies compared different dyads’ performances, though did not allow an actual choice among partners. We tested eleven ravens, Corvus corax, in triads, giving them first the choice to cooperate with either a highly familiar or a rather unfamiliar partner and, second, with either a friend or a non-friend using a cooperative string-pulling task. In either test, the ravens had a second choice and could cooperate with the other partner, given that this one had not pulled the string in the meantime. We show that during the experiments, these partner ravens indeed learn to wait and inhibit pulling, respectively. Moreover, the results of these two experiments show that ravens’ preferences for a specific cooperation partner are not based on familiarity. In contrast, the ravens did show a preference based on relationship quality, as they did choose to cooperate significantly more with friends than with non-friends and they were also more proficient when cooperating with a friend. In order to further identify the proximate mechanism of this preference, we designed an open-choice experiment for the whole group where all birds were free to cooperate on two separate apparatuses. This set-up allowed us to distinguish between preferences for close proximity and preferences to cooperate. The results revealed that friends preferred staying close to each other, but did not necessarily cooperate with one another, suggesting that tolerance of proximity and not relationship quality as a whole may be the driving force behind partner choice in raven cooperation. Consequently, we stress the importance of experiments that allow such titrations and, suggest that these results have important implications for the interpretations of cooperation studies that did not include open partner choice. PMID:27286247

  18. Accounting for Transport Parameter Uncertainty in Geostatistical Groundwater Contaminant Release History Estimation

    NASA Astrophysics Data System (ADS)

    Ostrowski, J.; Shlomi, S.; Michalak, A.

    2007-12-01

    The process of estimating the release history of a contaminant in groundwater relies on coupling a limited number of concentration measurements with a groundwater flow and transport model in an inverse modeling framework. The information provided by available measurements is generally not sufficient to fully characterize the unknown release history; therefore, an accurate assessment of the estimation uncertainty is required. The modeler's level of confidence in the transport parameters, expressed as pdfs, can be incorporated into the inverse model to improve the accuracy of the release estimates. In this work, geostatistical inverse modeling is used in conjunction with Monte Carlo sampling of transport parameters to estimate groundwater contaminant release histories. Concentration non-negativity is enforced using a Gibbs sampling algorithm based on a truncated normal distribution. The method is applied to two one-dimensional test cases: a hypothetical dataset commonly used in validating contaminant source identification methods, and data collected from a tetrachloroethylene and trichloroethylene plume at the Dover Air Force Base in Delaware. The estimated release histories and associated uncertainties are compared to results from a geostatistical inverse model where uncertainty in transport parameters is ignored. Results show that the a posteriori uncertainty associated with the model that accounts for parameter uncertainty is higher, but that this model provides a more realistic representation of the release history based on available data. This modified inverse modeling technique has many applications, including assignment of liability in groundwater contamination cases, characterization of groundwater contamination, and model calibration.

  19. 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.

  20. Image Denoising via Bayesian Estimation of Statistical Parameter Using Generalized Gamma Density Prior in Gaussian Noise Model

    NASA Astrophysics Data System (ADS)

    Kittisuwan, Pichid

    2015-03-01

    The application of image processing in industry has shown remarkable success over the last decade, for example, in security and telecommunication systems. The denoising of natural image corrupted by Gaussian noise is a classical problem in image processing. So, image denoising is an indispensable step during image processing. This paper is concerned with dual-tree complex wavelet-based image denoising using Bayesian techniques. One of the cruxes of the Bayesian image denoising algorithms is to estimate the statistical parameter of the image. Here, we employ maximum a posteriori (MAP) estimation to calculate local observed variance with generalized Gamma density prior for local observed variance and Laplacian or Gaussian distribution for noisy wavelet coefficients. Evidently, our selection of prior distribution is motivated by efficient and flexible properties of generalized Gamma density. The experimental results show that the proposed method yields good denoising results.

  1. Pairomics, the omics way to mate choice.

    PubMed

    Dani, Sergio Ulhoa; März, Winfried; Neves, Paulo Mauricio Serrano; Walter, Gerhard Franz

    2013-10-01

    The core aspects of the biology and evolution of sexual reproduction are reviewed with a focus on the diploid, sexually reproducing, outbreeding, polymorphic, unspecialized, altricial and cultural human species. Human mate choice and pair bonding are viewed as central to individuals' lives and to the evolution of the species, and genetic assistance in reproduction is viewed as a universal human right. Pairomics is defined as an emerging branch of the omics science devoted to the study of mate choice at the genomic level and its consequences for present and future generations. In pairomics, comprehensive genetic information of individual genomes is stored in a database. Computational tools are employed to analyze the mating schemes and rules that govern mating among the members of the database. Mating models and algorithms simulate the outcomes of mating any given genome with each of a number of genomes represented in the database. The analyses and simulations may help to understand mating schemes and their outcomes, and also contribute a new cue to the multicued schemes of mate choice. The scientific, medical, evolutionary, ethical, legal and social implications of pairomics are far reaching. The use of genetic information as a search tool in mate choice may influence our health, lifestyle, behavior and culture. As knowledge on genomics, population genetics and gene-environment interactions, as well as the size of genomic databases expand, so does the ability of pairomics to investigate and predict the consequences of mate choice for the present and future generations.

  2. 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

  3. Partner choice creates fairness in humans

    PubMed Central

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

    2015-01-01

    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. PMID:25972467

  4. 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

  5. Subject–Motion Correction in HARDI Acquisitions: Choices and Consequences

    PubMed Central

    Elhabian, Shireen; Gur, Yaniv; Vachet, Clement; Piven, Joseph; Styner, Martin; Leppert, Ilana R.; Pike, G. Bruce; Gerig, Guido

    2014-01-01

    Diffusion-weighted imaging (DWI) is known to be prone to artifacts related to motion originating from subject movement, cardiac pulsation, and breathing, but also to mechanical issues such as table vibrations. Given the necessity for rigorous quality control and motion correction, users are often left to use simple heuristics to select correction schemes, which involves simple qualitative viewing of the set of DWI data, or the selection of transformation parameter thresholds for detection of motion outliers. The scientific community offers strong theoretical and experimental work on noise reduction and orientation distribution function (ODF) reconstruction techniques for HARDI data, where post-acquisition motion correction is widely performed, e.g., using the open-source DTIprep software (1), FSL (the FMRIB Software Library) (2), or TORTOISE (3). Nonetheless, effects and consequences of the selection of motion correction schemes on the final analysis, and the eventual risk of introducing confounding factors when comparing populations, are much less known and far beyond simple intuitive guessing. Hence, standard users lack clear guidelines and recommendations in practical settings. This paper reports a comprehensive evaluation framework to systematically assess the outcome of different motion correction choices commonly used by the scientific community on different DWI-derived measures. We make use of human brain HARDI data from a well-controlled motion experiment to simulate various degrees of motion corruption and noise contamination. Choices for correction include exclusion/scrubbing or registration of motion corrupted directions with different choices of interpolation, as well as the option of interpolation of all directions. The comparative evaluation is based on a study of the impact of motion correction using four metrics that quantify (1) similarity of fiber orientation distribution functions (fODFs), (2) deviation of local fiber orientations, (3) global

  6. Subject-Motion Correction in HARDI Acquisitions: Choices and Consequences.

    PubMed

    Elhabian, Shireen; Gur, Yaniv; Vachet, Clement; Piven, Joseph; Styner, Martin; Leppert, Ilana R; Pike, G Bruce; Gerig, Guido

    2014-01-01

    Diffusion-weighted imaging (DWI) is known to be prone to artifacts related to motion originating from subject movement, cardiac pulsation, and breathing, but also to mechanical issues such as table vibrations. Given the necessity for rigorous quality control and motion correction, users are often left to use simple heuristics to select correction schemes, which involves simple qualitative viewing of the set of DWI data, or the selection of transformation parameter thresholds for detection of motion outliers. The scientific community offers strong theoretical and experimental work on noise reduction and orientation distribution function (ODF) reconstruction techniques for HARDI data, where post-acquisition motion correction is widely performed, e.g., using the open-source DTIprep software (1), FSL (the FMRIB Software Library) (2), or TORTOISE (3). Nonetheless, effects and consequences of the selection of motion correction schemes on the final analysis, and the eventual risk of introducing confounding factors when comparing populations, are much less known and far beyond simple intuitive guessing. Hence, standard users lack clear guidelines and recommendations in practical settings. This paper reports a comprehensive evaluation framework to systematically assess the outcome of different motion correction choices commonly used by the scientific community on different DWI-derived measures. We make use of human brain HARDI data from a well-controlled motion experiment to simulate various degrees of motion corruption and noise contamination. Choices for correction include exclusion/scrubbing or registration of motion corrupted directions with different choices of interpolation, as well as the option of interpolation of all directions. The comparative evaluation is based on a study of the impact of motion correction using four metrics that quantify (1) similarity of fiber orientation distribution functions (fODFs), (2) deviation of local fiber orientations, (3) global

  7. 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)

  8. School Choice, Competition, and Academic Quality: Essays on the Milwaukee Parental Choice Program

    ERIC Educational Resources Information Center

    Mader, Nicholas Salomon

    2010-01-01

    The essays of this dissertation contribute to the understanding of how public schools respond to competition in educational markets. Evidence is drawn from the Milwaukee Parental Choice Program, the longest-running and largest-scale private school voucher program in the United States. A major justification school choice programs is that they…

  9. 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…

  10. Preferences, Information, and Parental Choice Behavior in Public School Choice. NBER Working Paper No. 12995

    ERIC Educational Resources Information Center

    Hastings, Justine S.; Van Weelden, Richard; Weinstein, Jeffrey

    2007-01-01

    The incentives and outcomes generated by public school choice depend to a large degree on parents' choice behavior. There is growing empirical evidence that low-income parents place lower weights on academics when choosing schools, but there is little evidence as to why. We use a field experiment in the Charlotte-Mecklenburg Public School district…

  11. Choice Making Part II: Parental Choices and Decision-Making--Navigating Your Child's Cognitive Assessment

    ERIC Educational Resources Information Center

    Omichinski, Donna; Van Tubbergen, Marie; Warschausky, Seth

    2007-01-01

    Parenting a child with special needs can be perplexing and overwhelming journey which requires parents to make choices in unfamiliar territory. The manner in which parents make choices for their children establishes a model and sets a tone for what they expect their children to learn as well as what we expect of the people who serve their…

  12. Choice and Opportunity: The Past and Future of Choice-Based Aid in Louisiana

    ERIC Educational Resources Information Center

    Carpenter, Dick M., II; Ross, John K.

    2008-01-01

    On February 29, 2008, Gov. Bobby Jindal presented the Louisiana Legislature with a proposed budget allocating $10 million for a school choice initiative that would enable parents in New Orleans to send their children to the school of their choice, including private schools, with state-funded scholarships. Leaders of the public school establishment…

  13. Efficient and Flexible Strategy Use on Multi-Digit Sums: A Choice/No-Choice Study

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Verschaffel, Lieven

    2013-01-01

    This study analysed children's use of mental computation strategies and standard written algorithms in the domain of multi-digit addition and subtraction, using the choice/no-choice method. Twenty-one Flemish fourth-graders (M[subscript Age] =9y10m) solved problem-items that either stimulated the use of mental computation strategies or a standard…

  14. 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…

  15. 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…

  16. 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…

  17. Visual mate choice in poison frogs.

    PubMed Central

    Summers, K; Symula, R; Clough, M; Cronin, T

    1999-01-01

    We investigated female mate choice on the basis of visual cues in two populations of Dendrobates pumilio, the strawberry poison frog, from the Bocas del Toro Archipelago in Panama, Central America. Mate choice experiments were carried out by presenting subject females of each of two morphs of this species (orange and green) from two different island populations (Nancy Key and Pope Island) with object frogs (one of each morph) under glass at one end of a terrarium. Recorded calls were played simultaneously from behind both object frogs. The experiments were carried out under two light regimes: (i) white light, and (ii) relatively monochromatic filtered blue light. Subject females from each population displayed a significant preference for their own morph under white light, but not under blue light. These results indicate that female D. pumilio use visual cues in mate choice, and suggest that colour may be the visual cue they use. PMID:10649631

  18. Wheeler thought experiment with delayed choice

    NASA Astrophysics Data System (ADS)

    Boyd, Jeffrey

    2012-02-01

    This is an alternative interpretation of Jacques, et. al. (2007), Wheeler's thought experiment with delayed choice. The researchers find that the choice of observables changes the previous behavior of the photon inside the interferometer. Stepping outside the QM box, we propose that elementary waves from the detectors travel backwards through the interferometer, and the photon is following such a ray in the reverse direction. Thus a change in observables changes the behavior of the photon for the simple reason that the observable is transmitting information to the photon and the photon is able to change its polarization mid-stream in response to a change in that information. According to this explanation there is no delayed choice. It is an illusion.

  19. A quantitative analysis of extreme choice.

    PubMed

    Davison, M; Jones, B M

    1995-09-01

    Six homing pigeons were trained on a variety of concurrent variable-interval schedules in a switching-key procedure. Unlike previous work, reinforcer ratios of up to 160 to 1 and concurrent extinction variable-interval schedules were arranged in order to investigate choice when reinforcer-frequency outcomes were extremely different. The data obtained over 11 conditions were initially analyzed according to the generalized matching law, which fitted the data well. The generalized matching law was then fitted only to conditions in which the reinforcer ratios were between 1 to 10 and 10 to 1. The deviations of choice measures from the other four more extreme reinforcer-ratio conditions were significantly more towards equal choice than predicted by this second generalized matching fit. A contingency-discriminability model, which predicts such deviations, described the data more effectively than did the generalized matching law, and also correctly predicted the maintenance of responding on both alternatives when one was associated with extinction.

  20. Does Presentation Order Impact Choice After Delay?

    PubMed

    Berger, Jonah

    2016-07-01

    Options are often presented incidentally in a sequence, but does serial position impact choice after delay, and if so, how? We address this question in a consequential real-world choice domain. Using 25 years of citation data, and a unique identification strategy, we examine the relationship between article order (i.e., position in a journal issue) and citation count. Results indicate that mere serial position affects the prominence that research achieves: Earlier-listed articles receive more citations. Furthermore, our identification strategy allows us to cast doubt on alternative explanations (i.e., editorial placement) and instead indicate that the effect is driven by psychological processes of attention and memory. These findings deepen the understanding of how presentation order impacts choice, suggest that subtle presentation factors can bias an important scientific metric, and shed light on how psychological processes shape collective outcomes.

  1. Does educational indebtedness affect physician specialty choice?

    PubMed

    Bazzoli, G J

    1985-03-01

    There has been much debate over the effect of educational indebtedness on the specialty choices of new physicians, especially in light of the perceived shortage of primary care physicians. This paper explores the theoretical foundations on which this debate is based. In addition, the paper estimates the effects of various types of debt on specialty choice. The results suggest that an increase in debt from subsidized loan sources (i.e., Guaranteed Student Loans, National Direct Student Loans, or Health Professions Student Loans) has mixed effects while an increase in debt from Health Education Assistance Loans reduces the likelihood of becoming a primary care physician. Though these effects are significant, they are very small in magnitude. Economic returns to certain specialties and personal background appear to play a more important role in specialty choice.

  2. Serotonergic Genotypes, Neuroticism, and Financial Choices

    PubMed Central

    Kuhnen, Camelia M.; Samanez-Larkin, Gregory R.; Knutson, Brian

    2013-01-01

    Life financial outcomes carry a significant heritable component, but the mechanisms by which genes influence financial choices remain unclear. Focusing on a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR), we found that individuals possessing the short allele of this gene invested less in equities, were less engaged in actively making investment decisions, and had fewer credit lines. Short allele carriers also showed higher levels of the personality trait neuroticism, despite not differing from others with respect to cognitive skills, education, or wealth. Mediation analysis suggested that the presence of the 5-HTTLPR short allele decreased real life measures of financial risk taking through its influence on neuroticism. These findings show that 5-HTTLPR short allele carriers avoid risky and complex financial choices due to negative emotional reactions, and have implications for understanding and managing individual differences in financial choice. PMID:23382929

  3. When good news leads to bad choices.

    PubMed

    McDevitt, Margaret A; Dunn, Roger M; Spetch, Marcia L; Ludvig, Elliot A

    2016-01-01

    Pigeons and other animals sometimes deviate from optimal choice behavior when given informative signals for delayed outcomes. For example, when pigeons are given a choice between an alternative that always leads to food after a delay and an alternative that leads to food only half of the time after a delay, preference changes dramatically depending on whether the stimuli during the delays are correlated with (signal) the outcomes or not. With signaled outcomes, pigeons show a much greater preference for the suboptimal alternative than with unsignaled outcomes. Key variables and research findings related to this phenomenon are reviewed, including the effects of durations of the choice and delay periods, probability of reinforcement, and gaps in the signal. We interpret the available evidence as reflecting a preference induced by signals for good news in a context of uncertainty. Other explanations are briefly summarized and compared. PMID:26781050

  4. 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

  5. Computational mate choice: theory and empirical evidence.

    PubMed

    Castellano, Sergio; Cadeddu, Giorgia; Cermelli, Paolo

    2012-06-01

    The present review is based on the thesis that mate choice results from information-processing mechanisms governed by computational rules and that, to understand how females choose their mates, we should identify which are the sources of information and how they are used to make decisions. We describe mate choice as a three-step computational process and for each step we present theories and review empirical evidence. The first step is a perceptual process. It describes the acquisition of evidence, that is, how females use multiple cues and signals to assign an attractiveness value to prospective mates (the preference function hypothesis). The second step is a decisional process. It describes the construction of the decision variable (DV), which integrates evidence (private information by direct assessment), priors (public information), and value (perceived utility) of prospective mates into a quantity that is used by a decision rule (DR) to produce a choice. We make the assumption that females are optimal Bayesian decision makers and we derive a formal model of DV that can explain the effects of preference functions, mate copying, social context, and females' state and condition on the patterns of mate choice. The third step of mating decision is a deliberative process that depends on the DRs. We identify two main categories of DRs (absolute and comparative rules), and review the normative models of mate sampling tactics associated to them. We highlight the limits of the normative approach and present a class of computational models (sequential-sampling models) that are based on the assumption that DVs accumulate noisy evidence over time until a decision threshold is reached. These models force us to rethink the dichotomy between comparative and absolute decision rules, between discrimination and recognition, and even between rational and irrational choice. Since they have a robust biological basis, we think they may represent a useful theoretical tool for

  6. Dynamics of multiple-choice decision making.

    PubMed

    You, Hongzhi; Wang, Da-Hui

    2013-08-01

    Neuroscientists have carried out comprehensive experiments to reveal the neural mechanisms underlying the perceptual decision making that pervades daily life. These experiments have illuminated salient features of decision making, including probabilistic choice behavior, the ramping activity of decision-related neurons, and the dependence of decision time and accuracy on the difficulty of the task. Spiking network models have reproduced these features, and a two-dimensional mean field model has demonstrated that the saddle node structure underlies two-alternative decision making. Here, we reduced a spiking network model to an analytically tractable, partial integro-differential system and characterized not only multiple-choice decision behaviors but also the time course of neural activities underlying decisions, providing a mechanistic explanation for the observations noted in the experiments. First, we observed that a two-bump unstable steady state of the system is responsible for two-choice decision making, similar to the saddle node structure in the two-dimensional mean field model. However, for four-choice decision making, three types of unstable steady states collectively predominate the time course of the evolution from the initial state to the stable states. Second, the time constant of the unstable steady state can explain the fact that four-choice decision making requires a longer time than two-choice decision making. However, the quicker decision, given a stronger motion strength, cannot be explained by the time constant of the unstable steady state. Rather, the decision time can be attributed to the projection coefficient of the difference between the initial state and the unstable steady state on the eigenvector corresponding to the largest positive eigenvalue.

  7. 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. PMID:17806133

  8. Does Expert Advice Improve Educational Choice?

    PubMed Central

    2015-01-01

    This paper reports evidence that an individual meeting with a study counselor at high school significantly improves the quality of choice of tertiary educational field, as self-assessed 18 months after graduation from college. To address endogeneity, we explore the variation in study counseling practices between schools as an instrumental variable (IV). Following careful scrutiny of the validity of the IV, our results indicate a significant and positive influence of study counseling on the quality of educational choice, foremost among males and those with low educated parents. The overall result is stable across a number of robustness checks. PMID:26692388

  9. Redefining solubility parameters: the partial solvation parameters.

    PubMed

    Panayiotou, Costas

    2012-03-21

    The present work reconsiders a classical and universally accepted concept of physical chemistry, the solubility parameter. Based on the insight derived from modern quantum chemical calculations, a new definition of solubility parameter is proposed, which overcomes some of the inherent restrictions of the original definition and expands its range of applications. The original single solubility parameter is replaced by four partial solvation parameters reflecting the dispersion, the polar, the acidic and the basic character of the chemical compounds as expressed either in their pure state or in mixtures. Simple rules are adopted for the definition and calculation of these four parameters and their values are tabulated for a variety of common substances. In contrast, however, to the well known Hansen solubility parameters, their design and evaluation does not rely exclusively on the basic rule of "similarity matching" for solubility but it makes also use of the other basic rule of compatibility, namely, the rule of "complementarity matching". This complementarity matching becomes particularly operational with the sound definition of the acidic and basic components of the solvation parameter based on the third σ-moments of the screening charge distributions of the quantum mechanics-based COSMO-RS theory. The new definitions are made in a simple and straightforward manner, thus, preserving the strength and appeal of solubility parameter stemming from its simplicity. The new predictive method has been applied to a variety of solubility data for systems of pharmaceuticals and polymers. The results from quantum mechanics calculations are critically compared with the results from Abraham's acid/base descriptors. PMID:22327537

  10. Redefining solubility parameters: the partial solvation parameters.

    PubMed

    Panayiotou, Costas

    2012-03-21

    The present work reconsiders a classical and universally accepted concept of physical chemistry, the solubility parameter. Based on the insight derived from modern quantum chemical calculations, a new definition of solubility parameter is proposed, which overcomes some of the inherent restrictions of the original definition and expands its range of applications. The original single solubility parameter is replaced by four partial solvation parameters reflecting the dispersion, the polar, the acidic and the basic character of the chemical compounds as expressed either in their pure state or in mixtures. Simple rules are adopted for the definition and calculation of these four parameters and their values are tabulated for a variety of common substances. In contrast, however, to the well known Hansen solubility parameters, their design and evaluation does not rely exclusively on the basic rule of "similarity matching" for solubility but it makes also use of the other basic rule of compatibility, namely, the rule of "complementarity matching". This complementarity matching becomes particularly operational with the sound definition of the acidic and basic components of the solvation parameter based on the third σ-moments of the screening charge distributions of the quantum mechanics-based COSMO-RS theory. The new definitions are made in a simple and straightforward manner, thus, preserving the strength and appeal of solubility parameter stemming from its simplicity. The new predictive method has been applied to a variety of solubility data for systems of pharmaceuticals and polymers. The results from quantum mechanics calculations are critically compared with the results from Abraham's acid/base descriptors.

  11. When Choice Motivates and When It Does Not

    ERIC Educational Resources Information Center

    Katz, Idit; Assor, Avi

    2007-01-01

    This article addresses the controversy regarding the value of offering choices as a teaching practice. Inconsistent of results regarding the effects of choice in various settings suggest that choice can be either motivating or de-motivating. Based on the self-determination theory of motivation (Deci & Ryan, 2000), we propose that choice can be…

  12. The ABCs of School Choice, 2009-2010 Edition

    ERIC Educational Resources Information Center

    Friedman Foundation for Educational Choice, 2010

    2010-01-01

    This publication presents the 2009-2010 edition of the Friedman Foundation for Educational Choice's "ABCs of School Choice". The "ABCs of School Choice" provides the latest in up-to-date and accurate information about the many school choice success stories taking place throughout the country. Readers will find this guide an essential resource on…

  13. 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…

  14. School Choice and Segregation: "Tracking" Racial Equity in Magnet Schools

    ERIC Educational Resources Information Center

    Davis, Tomeka M.

    2014-01-01

    Three arguments regarding racial equity have arisen in the school choice debate. Choice advocates charge that choice will improve access to quality schools for disadvantaged minority students (Chubb & Moe 1990; Coons & Sugarman, 1978; Godwin & Kemerer, 2002; Viteritti, 1999). Critics argue that choice is unlikely to benefit minority…

  15. School Choice in America: The Great Debate. Hot Topics Series.

    ERIC Educational Resources Information Center

    Metcalf, Kim K., Ed.; Muller, Patricia A., Ed.; Legan, Natalie A., Ed.

    This document strives to answer questions about school choice, such as What does school choice mean?, What does school choice look like?, and What are the likely consequences of giving parents greater voice in their children's education? Reports are grouped into three thematic chapters. In chapter 1, "Public-Public Choice," reports include:…

  16. School Choice Signals: Research Review and Survey Experiments

    ERIC Educational Resources Information Center

    Carpenter, Dick M., II

    2014-01-01

    For the past several decades, a perennial topic on surveys about education has been school choice. Interest in public opinion about choice is more than just "nice to know." The results are often used to support or oppose choice in general or specific choice initiatives under consideration or adopted by state legislatures and even school…

  17. Educational Choice: New Roles for Board Members.

    ERIC Educational Resources Information Center

    Randall, Ruth E.

    1990-01-01

    School board members' new leadership roles in planning and implementing school choice programs are described in this article, which draws on the experience of a former Minnesota Commissioner of Education. The first task of the board is to set high expectations in the district and to establish specific policies. Despite the extent of…

  18. Choice of For-Profit College

    ERIC Educational Resources Information Center

    Chung, Anna S.

    2012-01-01

    In this paper I investigate whether students self-select into the U.S. for-profit colleges or whether the choice of for-profit sector is accidental or due to the reasons external to the students (geographic exposure to for-profit providers, tuition pricing, or random circumstances). The main student-level data samples come from the National…

  19. Partner Choice in Marriages and Cohabitations.

    ERIC Educational Resources Information Center

    Schoen, Robert; Weinick, Robin M.

    1993-01-01

    Examined data from National Survey of Families and Households to examine partner choice in cohabitations and marriages. Results support view of cohabitation as distinct type of relationship from marriage. Compared to recently married persons, cohabitors showed greater propensity to choose partner with same education and lesser propensity to choose…

  20. Direct and indirect mate choice on leks.

    PubMed

    Saether, Stein Are; Baglo, Ragnhild; Fiske, Peder; Ekblom, Robert; Höglund, Jacob; Kålås, John Atle

    2005-08-01

    Indirect mate choice is any behavior that restricts the individual's set of potential mates without discrimination of mate attributes directly, for example, by having preferences about where to mate. We analyzed a 14-year data set from great snipe (Gallinago media) leks for evidence of indirect mate choice based on relative and absolute position of lek territories. We found little or no effect of the centrality of territories on mating and no between-year consistency in the spatial distribution of matings within leks. Instead, the probability of matings occurring at a particular site increased if the current territory owner had mated the previous year. Furthermore, individual females returned in later seasons to mate with the same male as previously rather than at the same site. Previous work found that male interactions and dominance do not control matings and that females are very choosy about which territory they mate in. Here we show that this is because of the male occupying the territory rather than its position. We therefore conclude that direct female mate choice is the main behavioral process affecting variation in mating success among great snipe males, unlike in some lekking mammals where male competition and/or indirect mate choice appears more important.

  1. Dating Choices of High School Students

    ERIC Educational Resources Information Center

    Hansen, Sally L.

    1977-01-01

    Dating is experienced by most adolescents in our society as a prelude to mate selection. White and black youth (N=354) were studied to measure their dating-mating choices. Implications for teachers and practitioners, based on racial and gender differences, as well as perceived peer group influences are discussed. (Author)

  2. Unconscious Factors in Choice of a Mate

    ERIC Educational Resources Information Center

    Ottenheimer, Lilly

    1971-01-01

    If the selection of a spouse is based on the unconscious wish to correct disturbances which previously existed in the parent child relationship, the marriage is threatened from the start. This article examines motivations derived from early developmental phases which form convictions which later become the nucleus for mate choice. (Author/CJ)

  3. Understanding Adolescent Contraceptive Choice: An Empirical Test.

    ERIC Educational Resources Information Center

    Adler, Nancy E.; And Others

    Research using expectancy models has shown contraceptive choice among adults to be a rational process in that intentions and behaviors reflect an individual's beliefs, values, attitudes, and perceptions of social norms. This study examined whether such an approach could accurately represent adolescents' contraceptive decision-making. It used the…

  4. The Role of Nostalgia in School Choice.

    ERIC Educational Resources Information Center

    Gorard, Stephen

    1998-01-01

    Examines factors influencing choice of a new school, using data from a large-scale study in Wales. The "domino effect" sometimes covers three generations; decisions made today reflect, but are not identical to, past decisions. Simple reproduction cannot explain this diversity. Consumer nostalgia may lead schools to conservatism and restorationism.…

  5. School Choice Evidence and Its Significance

    ERIC Educational Resources Information Center

    Merrifield, John

    2008-01-01

    Pressing questions about the merits of full-fledged market accountability in K-12 education, and more limited choice programs, have spawned a large scholarly literature. This article assesses what we know from the most prominent studies and the importance of those findings to school system reform discussions. The studies most widely cited in the…

  6. Freedom and Learning: The Need for Choice

    ERIC Educational Resources Information Center

    Goodman, Paul

    1973-01-01

    Argues that the young can be educated entirely in terms of their free choice, with no processing whatsoever. Suggests that most of the money now spent for high schools and colleges should be devoted to the support of apprenticeships, travel, subsidized browsing in libraries, and self-directed study and research; and to support other volunteer…

  7. Neural Correlates of Affective Influence on Choice

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  8. Career Choices Among Saudi Medical Students.

    ERIC Educational Resources Information Center

    Al-Faris, Eiad; And Others

    1997-01-01

    A survey of 253 final-year students at the four Saudi medical schools found the most frequently-chosen specialties were internal medicine, surgery, pediatrics, and obstetrics/gynecology. Over one-fourth were unsure of career choice. Gender differences were found. Most common locations for postgraduate training were Saudi Arabia and Canada, and a…

  9. Probabilistic Choice, Reversibility, Loops, and Miracles

    NASA Astrophysics Data System (ADS)

    Stoddart, Bill; Bell, Pete

    We consider an addition of probabilistic choice to Abrial's Generalised Substitution Language (GSL) in a form that accommodates the backtracking interpretation of non-deterministic choice. Our formulation is introduced as an extension of the Prospective Values formalism we have developed to describe the results from a backtracking search. Significant features are that probabilistic choice is governed by feasibility, and non-termination is strict. The former property allows us to use probabilistic choice to generate search heuristics. In this paper we are particularly interested in iteration. By demonstrating sub-conjunctivity and monotonicity properties of expectations we give the basis for a fixed point semantics of iterative constructs, and we consider the practical proof treatment of probabilistic loops. We discuss loop invariants, loops with probabilistic behaviour, and probabilistic termination in the context of a formalism in which a small probability of non-termination can dominate our calculations, proposing a method of limits to avoid this problem. The formal programming constructs described have been implemented in a reversible virtual machine (RVM).

  10. User Choice in Markets at Risk.

    ERIC Educational Resources Information Center

    Noble, Charles; Hill, Doug; Smith, Erica; Smith, Andrew

    2000-01-01

    Australia's "user choice" program, which provides public funds to training providers chosen by apprentices and trainees, was evaluated. The distinction between viable and at-risk training markets was not found to be an effective guide to decision making; local or regional decision making was preferable. (SK)

  11. Springfield Public Schools: Schools of Choice.

    ERIC Educational Resources Information Center

    Springfield Public Schools, MA.

    As part of the school improvement process, the Springfield Public School (Massachusetts) has involved all constituencies in the community in implementing the Schools of Choice plan. This guidebook was prepared to assist parents and students in determining the best program and schools for their needs and desires. Parents of elementary school…

  12. Incentives, Choice, Education and Well-Being

    ERIC Educational Resources Information Center

    Schwartz, Barry

    2009-01-01

    It is a truism that giving people multiple reasons to engage in some activity will increase the chances of that activity--that two reasons are better than one. It is another truism, in the developed, Western world, that more freedom brings more well-being, and that more choice brings more freedom. In education, these truisms have led to the use of…

  13. 45 CFR 98.30 - Parental choice.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Parental Rights and Responsibilities § 98.30 Parental choice. (a) The parent or parents of an eligible child who receives or is offered child care services shall...

  14. 45 CFR 98.30 - Parental choice.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Parental Rights and Responsibilities § 98.30 Parental choice. (a) The parent or parents of an eligible child who receives or is offered child care services shall...

  15. 45 CFR 98.30 - Parental choice.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Parental Rights and Responsibilities § 98.30 Parental choice. (a) The parent or parents of an eligible child who receives or is offered child care services shall...

  16. 45 CFR 98.30 - Parental choice.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Parental Rights and Responsibilities § 98.30 Parental choice. (a) The parent or parents of an eligible child who receives or is offered child care services shall...

  17. 45 CFR 98.30 - Parental choice.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Welfare Department of Health and Human Services GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Parental Rights and Responsibilities § 98.30 Parental choice. (a) The parent or parents of an eligible child who receives or is offered child care services shall...

  18. The Probabilistic Nature of Preferential Choice

    ERIC Educational Resources Information Center

    Rieskamp, Jorg

    2008-01-01

    Previous research has developed a variety of theories explaining when and why people's decisions under risk deviate from the standard economic view of expected utility maximization. These theories are limited in their predictive accuracy in that they do not explain the probabilistic nature of preferential choice, that is, why an individual makes…

  19. Motivating Readers through Voice and Choice

    ERIC Educational Resources Information Center

    Ranck-Buhr, Wendy, Ed.

    2012-01-01

    As both a teacher and a parent, Ranck-Buhr knows a little something about working with students and keeping them engaged in the reading and writing processes... even recalling a son who was a reluctant book-report writer until he was offered some choice of reading material. She suggests practical ways to implement two vital elements in the…

  20. Program to Combat Stereotyping in Career Choice.

    ERIC Educational Resources Information Center

    Harrison, Laurie R.

    Divided into three sections which deal with sex, race, and handicap stereotyping in career choice, the twenty-eight programs described here attempt to combat stereotypes among students and/or staff (K-12). Most descriptions list the goals of the program, target population, staffing and management, facilities and activities, program effectiveness…

  1. Personality Factors and Occupational Specialty Choice.

    ERIC Educational Resources Information Center

    Borges, Nicole J.; Jones, Bonnie J.

    This study is a continuation of an earlier investigation of personality and medical specialty choice. The earlier study determined that personality differences existed among family practitioners, anesthesiologists, and general surgeons. Based on this initial research, an attempt was made to answer the question of how the personality factors of…

  2. 2012 ABCs of School Choice: Rising Tide

    ERIC Educational Resources Information Center

    DiPerna, Paul, Ed.

    2012-01-01

    School choice is a common sense idea that gives all parents the power and freedom to choose their child's education, while encouraging healthy competition among schools and other institutions to better serve students' needs and priorities. It is a public policy that allows a parent/guardian or student to choose a district, charter, or private…

  3. Intention in School Choice among Finnish Parents

    ERIC Educational Resources Information Center

    Raty, Hannu

    2013-01-01

    The study explored Finnish parents' intention in making school choices and the relationship of those intentions to demographic and attitudinal factors. It was found that the great majority of parents had not seriously considered choosing a school other than the neighbouring one. Parents living in urban areas, or those supporting a selective…

  4. Public School Choice Pushed in Michigan

    ERIC Educational Resources Information Center

    Cavanagh, Sean

    2011-01-01

    At a time when many states are adopting controversial measures to launch or expand private school vouchers, Republicans in Michigan are taking a different direction, moving ahead with a plan that would greatly expand the menu of public school choices for students and parents. GOP lawmakers, who control both state legislative chambers, have…

  5. Behaviors, Noncognitive Skills, and School Choice

    ERIC Educational Resources Information Center

    Mills, Jonathan N.

    2013-01-01

    While choice opponents and proponents tend to focus on how programs impact achievement, the growing body of research indicating a strong relationship between future outcomes and noncognitive skills indicates a need to broaden the basis for assessing programs. This article synthesizes the existing literature on the development of noncognitive…

  6. Choice Processes in a Newspaper Ethics Case.

    ERIC Educational Resources Information Center

    Borden, Sandra L.

    1997-01-01

    Examines choice processes of Midwestern newspaper staffers who participated in the professionally questionable decision to "kill" a photograph of a fatal wreck scene at the request of the victim's family. Shows how organizational routines, professional norms, and other factors entered into the decision through small-group communication and how…

  7. Code Choice in the Language Classroom

    ERIC Educational Resources Information Center

    Levine, Glenn S.

    2011-01-01

    Code Choice in the Language Classroom argues that the foreign language classroom is and should be regarded as a multilingual community of practice rather than as a perpetually deficient imitator of an exclusive second-language environment. From a sociocultural and ecological perspective, Levine guides the reader through a theoretical, empirical,…

  8. The response dynamics of preferential choice.

    PubMed

    Koop, Gregory J; Johnson, Joseph G

    2013-12-01

    The ubiquity of psychological process models requires an increased degree of sophistication in the methods and metrics that we use to evaluate them. We contribute to this venture by capitalizing on recent work in cognitive science analyzing response dynamics, which shows that the bearing information processing dynamics have on intended action is also revealed in the motor system. This decidedly "embodied" view suggests that researchers are missing out on potential dependent variables with which to evaluate their models-those associated with the motor response that produces a choice. The current work develops a method for collecting and analyzing such data in the domain of decision making. We first validate this method using widely normed stimuli from the International Affective Picture System (Experiment 1), and demonstrate that curvature in response trajectories provides a metric of the competition between choice options. We next extend the method to risky decision making (Experiment 2) and develop predictions for three popular classes of process model. The data provided by response dynamics demonstrate that choices contrary to the maxim of risk seeking in losses and risk aversion in gains may be the product of at least one "online" preference reversal, and can thus begin to discriminate amongst the candidate models. Finally, we incorporate attentional data collected via eye-tracking (Experiment 3) to develop a formal computational model of joint information sampling and preference accumulation. In sum, we validate response dynamics for use in preferential choice tasks and demonstrate the unique conclusions afforded by response dynamics over and above traditional methods.

  9. Matching, Demand, Maximization, and Consumer Choice

    ERIC Educational Resources Information Center

    Wells, Victoria K.; Foxall, Gordon R.

    2013-01-01

    The use of behavioral economics and behavioral psychology in consumer choice has been limited. The current study extends the study of consumer behavior analysis, a synthesis between behavioral psychology, economics, and marketing, to a larger data set. This article presents the current work and results from the early analysis of the data. We…

  10. Language Choice among Iranians in Sweden

    ERIC Educational Resources Information Center

    Namei, Shidrokh

    2008-01-01

    This study explores the language choice among Iranians in Sweden, both inside and outside the home domain. The data are collected from 188 participants through structured interviews and questionnaires. The results show that Persian is the main instrument of communication in the home domain between parents and children. However, some Swedish is…

  11. Turning to Teaching: Gender and Career Choice

    ERIC Educational Resources Information Center

    Raggl, Andrea; Troman, Geoff

    2008-01-01

    As the largest public sector institution in the United Kingdom, education is a key site for studying the context of "choice" and changes in the identities of professional workers in contemporary society. Recruitment and retention problems in education have led to the creation of new routes into teaching to attract career changers from other…

  12. School Choice Litigation after "Zelman" and "Locke"

    ERIC Educational Resources Information Center

    Liekweg, John A.

    2004-01-01

    In the past 2 years, the United States Supreme Court has decided two important cases that will bear directly on legislation and litigation involving school choice programs that provide financial aid to parents of children attending religious schools. Those cases are "Zelman v. Simmons-Harris" (2002) and "Locke v. Davey" (2004). The reasoning in…

  13. Choices and Motivations of Infertile Couples.

    ERIC Educational Resources Information Center

    van Balen, Frank; Verdurmen, Jacqueline; Ketting, Evert

    1997-01-01

    Infertile couples' (N=131) consideration of options for dealing with infertility (medical help, adoption, fostering, alternative medicine, and focusing on other life goals) is studied. Options were related to specific motivations including altruistic motives for adoption or foster care. Results, timing of choices, and motivations are discussed.…

  14. Doing School Choice Right: Preliminary Findings

    ERIC Educational Resources Information Center

    Harvey, James; Hill, Paul T.

    2006-01-01

    The Center on Reinventing Public Education (CRPE) has launched a new initiative entitled "Doing School Choice Right." Funded by the Bill and Melinda Gates, Annie E. Casey, and Lynde and Harry Bradley Foundations, the initiative's goal is to help state and local leaders handle practical issues whose resolution can determine whether school choice…

  15. More Choices, Higher Scores, and Worse Education

    ERIC Educational Resources Information Center

    American Educator, 2010

    2010-01-01

    If there is one thing all educators know and many studies have confirmed for decades, it is that there is no single answer to educational improvement. There are no grounds for the claim made in the past decade that accountability all by itself is a silver bullet, nor for the oft-asserted argument that choice by itself is a panacea. This article…

  16. Methodological Choices in Rating Speech Samples

    ERIC Educational Resources Information Center

    O'Brien, Mary Grantham

    2016-01-01

    Much pronunciation research critically relies upon listeners' judgments of speech samples, but researchers have rarely examined the impact of methodological choices. In the current study, 30 German native listeners and 42 German L2 learners (L1 English) rated speech samples produced by English-German L2 learners along three continua: accentedness,…

  17. Yaffa: A School of Their Choice?

    ERIC Educational Resources Information Center

    Levy, Gal; Massalha, Mohammad

    2010-01-01

    This article is a product of in-depth research in "Yaffa, The Arab Democratic School" that was carried out in 2004/05, as part of a study on alternative Arab education in Israel. Its aim, beyond telling the story of Yaffa, is to explicate the motivations that underlay this initiative, and to examine parental choice amongst the disadvantaged. We…

  18. Children's Choices: Teaching with Books Children Like.

    ERIC Educational Resources Information Center

    Roser, Nancy, Ed.; Frith, Margaret, Ed.

    Supplementing Children's Choices--a list of children's literature that children grades K-8 found most enjoyable, published annually in "The Reading Teacher" journal--this collection of articles provides suggestions for effective use of children's favorite books in the classroom. In addition to providing an extensive bibliography of Children's…

  19. Improving the Quality of Multiple Choice Examinations

    ERIC Educational Resources Information Center

    Shively, Michael Jay

    1978-01-01

    Some of the merits and pitfalls of multiple choice examinations are outlined and ways of increasing reliability and feedback information are summarized. Included are discussions of basic format, examples of poor design, examples of augmentation, and feedback from computerized grading. (LBH)

  20. Public School Choice: A Selected Annotated Bibliography.

    ERIC Educational Resources Information Center

    Crohn, Leslie; Hansen, Kenneth H.

    This annotated bibliography offers a sampling of a wide variety of viewpoints on the topic of school choice. Fourteen references selected for annotation, ranging from a 3-page journal article to a 266-page book, are listed at the beginning of the bibliography. Among the viewpoints that different authors represent are the following: (1) unlimited…

  1. Constructing Motivation through Choice, Interest, and Interestingness

    ERIC Educational Resources Information Center

    Patall, Erika A.

    2013-01-01

    Psychological research and theory have traditionally suggested that opportunities for choosing will lead to motivation and performance benefits. However, evidence on choice effects has not been ubiquitously positive, and recent investigations have revealed factors that diminish or reverse the effects of choosing. This investigation sought to…

  2. Choice: A Thematic Sequence of English Units.

    ERIC Educational Resources Information Center

    Institute for Services to Education, Inc., Washington, DC.

    One of a series of volumes containing units on specific themes designed for use in college freshman English courses, this particular volume considers the issue of choice through literature (short stories, novels, and poems). A section describing chamber theatre technique, which is an integral part of many of the units in this sequence, is…

  3. Evolutionary pressures on primate intertemporal choice.

    PubMed

    Stevens, Jeffrey R

    2014-07-01

    From finding food to choosing mates, animals must make intertemporal choices that involve fitness benefits available at different times. Species vary dramatically in their willingness to wait for delayed rewards. Why does this variation across species exist? An adaptive approach to intertemporal choice suggests that time preferences should reflect the temporal problems faced in a species's environment. Here, I use phylogenetic regression to test whether allometric factors relating to body size, relative brain size and social group size predict how long 13 primate species will wait in laboratory intertemporal choice tasks. Controlling for phylogeny, a composite allometric factor that includes body mass, absolute brain size, lifespan and home range size predicted waiting times, but relative brain size and social group size did not. These findings support the notion that selective pressures have sculpted intertemporal choices to solve adaptive problems faced by animals. Collecting these types of data across a large number of species can provide key insights into the evolution of decision making and cognition. PMID:24827445

  4. Choice Shift in Opinion Network Dynamics

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael

    Choice shift is a phenomenon associated with small group dynamics whereby group discussion causes group members to shift their opinions in a more extreme direction so that the mean post-discussion opinion exceeds the mean pre-discussion opinion. Also known as group polarization, choice shift is a robust experimental phenomenon and has been well-studied within social psychology. In opinion network models, shifts toward extremism are typically produced by the presence of stubborn agents at the extremes of the opinion axis, whose opinions are much more resistant to change than moderate agents. However, we present a model in which choice shift can arise without the assumption of stubborn agents; the model evolves member opinions and uncertainties using coupled nonlinear differential equations. In addition, we briefly describe the results of a recent experiment conducted involving online group discussion concerning the outcome of National Football League games are described. The model predictions concerning the effects of network structure, disagreement level, and team choice (favorite or underdog) are in accord with the experimental results. This research was funded by the Office of Naval Research and the Defense Threat Reduction Agency.

  5. Race, Inequality of Opportunity, and School Choice

    ERIC Educational Resources Information Center

    Darby, Derrick; Saatcioglu, Argun

    2015-01-01

    Both neoliberals and liberals call for mitigating inequality of educational opportunity stemming from circumstances beyond an individual's control. In this article, we challenge the wisdom of making equality of opportunity hinge on emphasizing the distinction rather than the relationship between choices and circumstances. We utilize an empirical…

  6. Addiction and Choice: Theory and New Data

    PubMed Central

    Heyman, Gene M.

    2013-01-01

    Addiction’s biological basis has been the focus of much research. The findings have persuaded experts and the public that drug use in addicts is compulsive. But the word “compulsive” identifies patterns of behavior, and all behavior has a biological basis, including voluntary actions. Thus, the question is not whether addiction has a biology, which it must, but whether it is sensible to say that addicts use drugs compulsively. The relevant research shows most of those who meet the American Psychiatric Association’s criteria for addiction quit using illegal drugs by about age 30, that they usually quit without professional help, and that the correlates of quitting include legal concerns, economic pressures, and the desire for respect, particularly from family members. That is, the correlates of quitting are the correlates of choice not compulsion. However, addiction is, by definition, a disorder, and thereby not beneficial in the long run. This is precisely the pattern of choices predicted by quantitative choice principles, such as the matching law, melioration, and hyperbolic discounting. Although the brain disease model of addiction is perceived by many as received knowledge it is not supported by research or logic. In contrast, well established, quantitative choice principles predict both the possibility and the details of addiction. PMID:23653607

  7. Gender and Choice in Education and Occupation.

    ERIC Educational Resources Information Center

    Radford, John, Ed.

    Nine chapters present cutting-edge research on "brainsex" and its effects on personality, education, and choice. It targets concepts such as job attributes, work flexibility, long-term life planning, home-work conflict, prestige versus occupational interest, and intrinsic motivational mechanisms to explain the relative failure of intervention…

  8. Women and the Choice to Study Economics

    ERIC Educational Resources Information Center

    Emerson, Tisha L. N.; McGoldrick, KimMarie; Mumford, Kevin J.

    2012-01-01

    Underrepresentation of women in economics is documented in many studies. Investigation of its sources at the undergraduate level is examined through students' decisions to persist in economics, either beyond an introductory course or in their major choices. The authors add to the literature by analyzing students' decisions to take their first…

  9. Today`s fluorescent lamp choice

    SciTech Connect

    Foszcz, J.L.

    1997-10-01

    The choice of fluorescent lamps to replace the old standbys presents an opportunity to improve the quality of lighting, make a significant reduction in electrical bills, and contribute to improvement of the environment. The paper discusses the new electronic ballasts available today, the Green Light program to encourage US corporations to install energy efficient lighting in their facilities, and disposal of fluorescent lamps.

  10. School Choice and State Constitutions' Religion Clauses

    ERIC Educational Resources Information Center

    Komer, Richard D.

    2009-01-01

    After the U.S. Supreme Court's decision in "Zelman v. Simmons-Harris," only state religion clauses represent a potential constitutional bar to the inclusion of religious options in properly designed school choice programs. The two most significant are compelled support clauses and Blaine Amendments. Both are frequently misinterpreted by state…

  11. School Choice Tradeoffs: Liberty, Equity and Diversity.

    ERIC Educational Resources Information Center

    Godwin, R. Kenneth; Kemerer, Frank R.

    Education policy should encourage liberty and equality of opportunity, political tolerance, respect for diversity, and citizenship. The authors compare current policy that uses family residence to assign students to schools with alternative policies that range from expanding public choice options to school vouchers. They identify the benefits and…

  12. Preparing Teachers for Schools of Choice.

    ERIC Educational Resources Information Center

    Raywid, Mary Anne

    Schools of choice, established to respond to varying student and parent needs and interests, have unique features that require special teacher attributes. Programs preparing teachers for these schools include more emphasis upon: (1) content preparation, (2) the context of schools and classrooms; (3) the psychology of human growth and development;…

  13. Modeling Spanish Mood Choice in Belief Statements

    ERIC Educational Resources Information Center

    Robinson, Jason R.

    2013-01-01

    This work develops a computational methodology new to linguistics that empirically evaluates competing linguistic theories on Spanish verbal mood choice through the use of computational techniques to learn mood and other hidden linguistic features from Spanish belief statements found in corpora. The machine learned probabilistic linguistic models…

  14. Choice, SES Would Flip under Plan

    ERIC Educational Resources Information Center

    Robelen, Erik W.

    2006-01-01

    This article reports the plan of the U.S. Department of Education to expand a pilot initiative that would flip the order of key consequences for schools' low academic performance under the No Child Left Behind Act. Building on an initiative piloted in Virginia for school year 2006-2007, participating districts could offer a choice of supplemental…

  15. Investigating intertemporal choice through experimental evolutionary robotics.

    PubMed

    Paglieri, Fabio; Parisi, Domenico; Patacchiola, Massimiliano; Petrosino, Giancarlo

    2015-06-01

    In intertemporal choices, subjects face a trade-off between value and delay: achieving the most valuable outcome requires a longer time, whereas the immediately available option is objectively poorer. Intertemporal choices are ubiquitous, and comparative studies reveal commonalities and differences across species: all species devalue future rewards as a function of delay (delay aversion), yet there is a lot of inter-specific variance in how rapidly such devaluation occurs. These differences are often interpreted in terms of ecological rationality, as depending on environmental factors (e.g., feeding ecology) and the physiological and morphological constraints of different species (e.g., metabolic rate). Evolutionary hypotheses, however, are hard to verify in vivo, since it is difficult to observe precisely enough real environments, not to mention ancestral ones. In this paper, we discuss the viability of an approach based on evolutionary robotics: in Study 1, we evolve robots without a metabolism in five different ecologies; in Study 2, we evolve metabolic robots (i.e., robots that consume energy over time) in three different ecologies. The intertemporal choices of the robots are analyzed both in their ecology and under laboratory conditions. Results confirm the generality of delay aversion and the usefulness of studying intertemporal choice through experimental evolutionary robotics.

  16. Lesher Middle School: Commitment by Choice

    ERIC Educational Resources Information Center

    Principal Leadership, 2012

    2012-01-01

    This article features Lesher Middle School, a school of choice, as are all of the schools in the Poudre School District in Ft. Collins, Colorado. In 2004, it was a traditional junior high school with a declining enrollment that housed an application-based International Baccalaureate Middle Years Programme (IB MYP) that resulted in tracking…

  17. Developing a Model of Occupational Choice

    ERIC Educational Resources Information Center

    Egner, Joan Roos

    1974-01-01

    Rational and non-rational decision-making models of occupational choice are described. The Blau model provides an alternative to these. This model contains an occupational set of factors and a set related to the individual. Research supporting its conceptual utility and activities illustrating its pragmatic utility are discussed. (EAK)

  18. Career Choices for Women - New Determinants

    ERIC Educational Resources Information Center

    Sherman, Ruth G.; Jones, Jane H.

    1976-01-01

    Career choices for college women now depend upon different factors from those in the past. The new determinants have relevance for counselors and other college professionals. Despite contrary pressures, women are moving in the direction of economic independence and a high level of professional aspiration. (Author)

  19. Multiple Choice: Trends in Dining Design.

    ERIC Educational Resources Information Center

    Swanquist, Barry

    1999-01-01

    Examines changes in the traditional school dining hall and the prevailing trends in food-service design. Explores dining-hall space flexibility and multi-functionality and the need to cater to student preferences for brand names and choice. (GR)

  20. Mate Choice: Charting Desire's Tangled Bank.

    PubMed

    Rosenthal, Gil G

    2016-04-01

    Choosing a mate requires a way to turn sexual arousal into sexual action. A recent paper identifies a hormone receptor that acts as a molecular gatekeeper in reproductive decisions. Focusing on mate-choice mechanisms may clarify longstanding evolutionary puzzles in sexual selection and speciation. PMID:27046819

  1. Behavioural Approaches to Understanding Student Choice

    ERIC Educational Resources Information Center

    Diamond, Abigail; Vorley, Tim; Roberts, Jennifer; Jones, Stephen

    2012-01-01

    The Higher Education Academy (HEA), in partnership with the National Union of Students (NUS), commissioned CFE and The University of Sheffield to undertake research to explore behavioural approaches to understanding student choice. Within the research, the authors' applied insights from behavioural economics to help aid understanding of student…

  2. Restricted Liberty, Parental Choice and Homeschooling

    ERIC Educational Resources Information Center

    Merry, Michael S.; Karsten, Sjoerd

    2010-01-01

    In this paper the authors carefully study the problem of liberty as it applies to school choice, and whether there ought to be restricted liberty in the case of homeschooling. They examine three prominent concerns that might be brought against homeschooling, viz., that it aggravates social inequality, worsens societal conflict and works against…

  3. Making Choices: Life Skills for Adolescents. Curriculum.

    ERIC Educational Resources Information Center

    Halter, Mary H.; Lang, Barbara Fierro

    This text was designed to help adolescents develop skills which will encourage them to make healthy and positive choices about life. In addition, its design will assist adults, parents and teachers, as they guide young people through the process. The book uses a series of written exercises designed to help organize the students' goals and…

  4. Career Path Guide for Adult Career Choices.

    ERIC Educational Resources Information Center

    Case, Clydia

    Intended for adults who are considering career choices or changes, this booklet provides opportunities for self-study and reflection in six career paths. The booklet begins with tips for long-term career survival and myths and realities of career planning. After a brief career survey, readers are introduced to six career paths: arts and…

  5. Moral Choices in Contemporary Society: Source Book.

    ERIC Educational Resources Information Center

    Hellman, Mary, Ed.

    One of several supplementary materials for a newspaper course on moral choices in contemporary society, this sourcebook contains program ideas and resources to help civic leaders and educators plan programs based on the course topics. There are four sections. The first section explains how the topics can be used in planning programs, identifies…

  6. Does Challenge by Choice Increase Participation?

    ERIC Educational Resources Information Center

    Chase, Daniel L.

    2015-01-01

    Challenge by choice (CBC) has been regarded as a foundational principle for challenge ropes course programs. Although CBC is widely accepted as the primary mechanism for facilitating intended ropes course outcomes, especially a participant's involvement, until recently it had remained an untested assumption. This study explored the role of CBC as…

  7. Some Remarks on the Choice of Ductility Class for Earthquake-Resistant Steel Structures

    NASA Astrophysics Data System (ADS)

    Matejčeková-Farhat, Miroslava; Ároch, Rudolf

    2013-09-01

    The implementation of the Eurocodes in current structural design practice has brought about a new emphasis on the design of earthquake-resistant structures. In some European countries, new earthquake zones have been defined; henceforth, the design requirements of many ongoing projects have changed as well. The choice of the ductility class of steel structures as one of the key design parameters, the consequences of this choice on design procedure, and some applications of the Eurocode 8 design criteria by comparing French and Slovak national practice are discussed, using a practical example of a structure.

  8. Action and valence modulate choice and choice-induced preference change.

    PubMed

    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.

  9. The impact of gender and working experience on intertemporal choices

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Zhuang, Xintian

    2014-09-01

    Intertemporal choice has been drawing attention in econophysics and neuroeconomics. In this paper, we experimentally estimate the parameters and AICc (Akaike Information Criterion with small sample correction) of intertemporal choice models (exponential, simple hyperbolic, quasi hyperbolic, and q-exponential) for senior undergraduate students and MBA students, respectively. Our results show that (1) regardless of gender or working experience, q-exponential discount model always generates minimum AICc value, and it is thus the optimal discount model; (2) gender affects the degree of inconsistency and fitness of the discount model. Comparing to female participants, male participants have a higher degree of inconsistency while their discount pattern is better explained by q-exponential discount model; (3) working experience has an interaction effect with gender. For male participants, working experience is inversely related to the degree of inconsistency and the fitness of q-exponential discount model. On the contrary, for female participants, working experience is positively related to the degree of inconsistency and the fitness of q-exponential discount model.

  10. On the choice of calibration periods and objective functions: A practical guide to model parameter identification

    NASA Astrophysics Data System (ADS)

    Romanowicz, Renata; Osuch, Marzena; Grabowiecka, Magdalena

    2013-12-01

    Despite the development of new measuring techniques, monitoring systems and advances in computer technology, rainfall-flow modelling is still a challenge. The reasons are multiple and fairly well known. They include the distributed, heterogeneous nature of the environmental variables affecting flow from the catchment. These are precipitation, evapotranspiration and in some seasons and catchments in Poland, snow melt also. This paper presents a review of work done on the calibration and validation of rainfall-runoff modelling, with a focus on the conceptual HBV model. We give a synthesis of the problems and propose a practical guide to the calibration and validation of rainfall-runoff models.

  11. Abortion: a guide to making ethical choices.

    PubMed

    Maguire, M R; Maguire, D C

    1983-09-01

    A mature attitude toward abortion rests on responsible decision-making and action taking, not on the belief in irreversible events. Abortion is therefore a choice which should be made if it is the most correct and responsible action in view of one's own circumstances. There are a number of doubts, concerns and moral--as opposed to medical--questions that women may be asking themselves as they face this serious choice. The guide addresses these issues to help women think through that choice. It is important to know, for instance, that the Pope has never formally proclaimed a doctrine of faith on the matter of abortion. The Catholic Church, when considered in its diversity, teaches that some abortions can be moral; the conscience of a person is the final arbiter of any abortion decision. Conscience is humans' progressively refined ability to think about situations and evaluate their moral goodness/badness. With respect to abortion, this means that a woman should make the choice that seems best to her. The fear that having an abortion will result in excommunication from the Church is dismissed here. A distinction must be made between committing the sin of abortion and having an abortion. The former obtains when people act against their own conscience. The attitude toward abortion as murder and the issue of the fetus' afterlife are responded to in terms of personhood, a complicated concept on which there is no legal, scientific or religious consensus. Instead, the answer is a function of the time period and its prevalent beliefs. Today, the viability of the fetus has become an important determinant of life. Having an abortion, giving birth, and use of contraceptives when no children are wanted, are responses to which a woman is entitled. Her choice is moral when based on responsible and conscious decisions and actions. The views of Protestantism and Judaism on abortion are clarified briefly.

  12. Mate choice and uncertainty in the decision process.

    PubMed

    Wiegmann, Daniel D; Angeloni, Lisa M

    2007-12-21

    The behavior of females in search of a mate determines the likelihood that a high quality male is encountered in the search process and alternative search strategies provide different fitness returns to searchers. Models of search behavior are typically formulated on an assumption that the quality of prospective mates is revealed to searchers without error, either directly or by inspection of a perfectly informative phenotypic character. But recent theoretical developments suggest that the relative performance of a search strategy may be sensitive to any uncertainty associated with the to-be-realized fitness benefit of mate choice decisions. Indeed, uncertainty in the decision process is inevitable whenever unobserved male attributes influence the fitness of searchers. In this paper, we derive solutions to the sequential search strategy and the fixed sample search strategy for the general situation in which observed and unobserved male attributes affect the fitness consequences of female mate choice decisions and we determine how the magnitude of various parameters that are influential in the standard models alter these more general solutions. The distribution of unobserved attributes amongst prospective mates determines the uncertainty of mate choice decisions-the reliability of an observed male character as a predictor of male quality-and the realized functional relationship between an observed male character and the fitness return to searchers. The uncertainty of mate choice decisions induced by unobserved male attributes has no influence on the generalized model solutions. Thus, the results of earlier studies of these search models that rely on the use of a perfectly informative male character apply even if an observed male trait does not reveal the quality of prospective mates with certainty. But the solutions are sensitive to any changes of the distribution of unobserved male attributes that alter the realized functional relationship between an observed

  13. Choice, access, information are among clients' rights.

    PubMed

    Finger, W R

    1993-08-01

    This general discussion of the importance of respecting client's rights and access to a choice of methods relies on the statements of researchers and family planners from a variety of international and private organizations which reiterate the features of successful programs. The emphasis on client's rights is a change for many programs. The example is given of a clinic in Niger that posts the list of client rights to accessibility, information, education, communication, and freedom of choice. Pressure from international groups focuses on promoting client's informed and voluntary choice of family planning (FP) method, because it assures continuation. Quality of care is directly related to continuation of care. The quality of care framework of Judith Bruce, from the Population Council, identifies the first and most fundamental element in assuring quality of service to be choice of method. The UN assures that contraceptive choice is a basic human right. The International Planned Parenthood (IPPF) Medical and Service Delivery Guidelines proposes 10 client rights; this list of rights has been widely distributed as a poster. IPPF's African director states that contraceptive prevalence is low because of a lack of quality care. Women's rights have been integrated into FP and promoted in the Safe Motherhood Initiative and in the focus of the International Decade for Women, 1975-85. The International Women's Health Coalition, which is an alliance of over 100 women's organizations from 50 countries, has released a "Women's Declaration on Population Policies" at UN headquarters, which calls for provision of reproductive health care, not just technology, for fertility management by women. Policy makers and planners are urged to provide access to wide contraceptive choices, pregnancy care, safe abortion, prevention of sexually transmitted diseases (STDs), development of new technology for protection against STDs, and encouragement of men to take responsibility for sexual

  14. Choices at Space Station End of Life

    NASA Astrophysics Data System (ADS)

    Burke, J. D.; Coderre, K. M.; Dator, J. A.

    Extending International Space Station (ISS) operations will expand the scope for deciding its fate at its end of life. In this paper we examine the choices likely to be available at that distant unknown day when it is decided, for whatever reasons, to bring crew-directed engineering and science operations to a close. Of course a premature accidental termination is possible at any time, and measures to cope with that (and return to normal if possible) should be kept ready and augmented as ISS service capacities improve, but here we do not focus on accidents. Rather, we consider what may be done with an old but functioning spacecraft after it is declared surplus. We use the technique of Futures Studies to look at the choices. Without attempting prediction, futurists develop a set of empirically-based alternate futures, describe the likely consequences of each, and point to preferred outcomes. For the ISS at end of scheduled operation the choices are in three classes: DOWN, STAY, or UP. In the DOWN choice, after possible salvage and transfer of long-running investigations to another (e.g., Chinese-led) international station, the ISS is commanded to descend and burn up. The STAY choice, not viable in the long run, might be chosen to provide time for later decisions, but eventually it would prove impractical to continue re-boosting to maintain the station in Low Earth Orbit (LEO). In the UP choice the ISS is propelled, by heavy-lift boost impulses or a low-thrust spiral-out or a combination of both, into a high orbit with a lifetime of hundreds of years, opening the prospect of a wide variety of options to be compared in search of a preferred longer-term future. The decision to boost the ISS into a high orbit could be completely rational based on any of several arguments, or it could be partly irrational as in the case of the USS Constitution, an eighteenth- century warship saved from the ship-breakers by a poem.

  15. Contraceptive counselling and factors affecting women's contraceptive choices: results of the CHOICE study in Austria.

    PubMed

    Egarter, Christian; Grimm, Christoph; Nouri, Kazem; Ahrendt, Hans-Joachim; Bitzer, Johannes; Cermak, Christine

    2012-06-01

    Empirical evidence of the impact of contraceptive counselling and factors affecting women's contraceptive choices are limited. CHOICE (Contraceptive Health Research Of Informed Choice Experience) was a large-scale study in 11 European countries. Women in Austria aged 15-40 years considering a short-acting, reversible form of combined hormonal contraceptive were eligible to participate. The choices included the combined daily pill, weekly transdermal patch, and monthly vaginal ring. This study assessed and compared 2478 women's original preferences with their post-counselling choices and evaluated their perceptions and criteria for their choice. Women who were 'undecided' decreased from 18.1% pre-counselling to 3.2% post-counselling; significantly more women post-counselling chose the monthly ring (8.7% to 23.8%; difference 15.1%, 95% CI 13.3-16.8%; P<0.0001) or the weekly patch (6.2% to 7.8%; difference 1.7%, 95% CI 0.5-2.9%; P=0.0014). Women's primary reasons for choosing a method included 'easy to use' (daily pill, weekly patch and monthly ring) and 'still effective if I experience vomiting, diarrhoea' (weekly patch and monthly ring). Structured and balanced counselling led to changes in the method chosen.

  16. Choice ball: a response interface for two-choice psychometric discrimination in head-fixed mice

    PubMed Central

    Sanders, Joshua I.

    2012-01-01

    The mouse is an important model system for investigating the neural circuits mediating behavior. Because of advances in imaging and optogenetic methods, head-fixed mouse preparations provide an unparalleled opportunity to observe and control neural circuits. To investigate how neural circuits produce behavior, these methods need to be paired with equally well-controlled and monitored behavioral paradigms. Here, we introduce the choice ball, a response device that enables two-alternative forced-choice (2AFC) tasks in head-fixed mice based on the readout of lateral paw movements. We demonstrate the advantages of the choice ball by training mice in the random-click task, a two-choice auditory discrimination behavior. For each trial, mice listened to binaural streams of Poisson-distributed clicks and were required to roll the choice ball laterally toward the side with the greater click rate. In this assay, mice performed hundreds of trials per session with accuracy ranging from 95% for easy stimuli (large interaural click-rate contrast) to near chance level for low-contrast stimuli. We also show, using the record of individual paw strokes, that mice often reverse decisions they have already initiated and that decision reversals correlate with improved performance. The choice ball enables head-fixed 2AFC paradigms, facilitating the circuit-level analysis of sensory processing, decision making, and motor control in mice. PMID:23019000

  17. Consumer choice of pork chops in Taiwan.

    PubMed

    Chen, M T; Guo, H L; Tseng, T F; Roan, S W; Ngapo, T M

    2010-07-01

    Digital photographs of pork chops varying systematically in appearance were presented to 716 Taiwanese consumers in a study that aimed to identify the most important characteristics of fresh pork which determine consumer choice in Taiwan. Relationships between consumer segmentation in choice and socio-demographic and cultural differences were also investigated. Colour and fat cover were the most frequently chosen of the four characteristics studied. Dark red colour was preferred by 64% of consumers and lean fat cover by 44%. Marbling and drip were less important in the decision making process being used by less than a half of consumers. The four preference-based clusters of consumers showed no correlation with socio-demographic-based consumer clusters, but did show significant links with possession of a refrigerator, age at which schooling was completed, liking pork for its price and gender of consumer.

  18. Income and choice between different goods.

    PubMed

    Shurtleff, D; Warren-Boulton, F R; Silberberg, A

    1987-09-01

    In Experiment 1, 3 rats chose between two simultaneously operating variable-interval schedules, one of which provided saccharin water and the other, food. In five conditions, the absolute (and equal) reinforcement rates provided by the pair of equal-valued schedules were manipulated in the range of 36 to 240 per hour. Experiment 2 was identical to Experiment 1 except that these schedules operated successively, arranged by requiring the rat to stand on the side of the chamber correlated with each schedule. Food/saccharin choice ratios were inversely related to reinforcement rate in both experiments, although this effect was stronger in Experiment 2. When delivery rates were high, preference for food over saccharin often reversed as the session progressed. The results were interpretable in terms of economic accounts of choice (e.g., the minimum-needs hypothesis), as well as in terms of traditional psychological accounts (e.g., matching theory).

  19. Modified mandated choice for organ procurement

    PubMed Central

    Chouhan, P; Draper, H

    2003-01-01

    Presumed consent to organ donation looks increasingly unlikely to be a palatable option for increasing organ procurement in the UK following the publication of the report into events at Alder Hey and elsewhere. Yet, given that the alternative to increasing the number of cadaveric organs available is either to accept a greater number of live donations, or accept that people will continue to die for the want of an organ, public policy makers remain obliged to consider other means of increasing the procurement rate. In this paper, we meet the main objections to mandated choice (namely that it undermines autonomy and that mandated donation is preferable). We have modified the traditional approach to mandated choice to take into account the force of the objection that mandated donation is preferable, by accepting that people can and do make bad decisions about organ donation and proposing that all accompanying public education and information about cadaveric donation should be directed in favour of donation. PMID:12796435

  20. Sustainable food consumption. Product choice or curtailment?

    PubMed

    Verain, Muriel C D; Dagevos, Hans; Antonides, Gerrit

    2015-08-01

    Food consumption is an important factor in shaping the sustainability of our food supply. The present paper empirically explores different types of sustainable food behaviors. A distinction between sustainable product choices and curtailment behavior has been investigated empirically and predictors of the two types of behavior have been identified. Respondents were classified into four segments based on their sustainable food behaviors: unsustainers, curtailers, product-oriented consumers, and sustainers. Significant differences between the segments were found with regard to food choice motives, personal and social norms, food involvement, subjective knowledge on sustainable food, ability to judge how sustainably a product has been produced and socio-demographics. It is concluded that distinguishing between behavioral strategies toward sustainable food consumption is important as consumer segments can be identified that differ both in their level of sustainable food consumption and in the type of behavior they employ.

  1. Facultative mate choice drives adaptive hybridization.

    PubMed

    Pfennig, Karin S

    2007-11-01

    Mating with another species (hybridization) is often maladaptive. Consequently, females typically avoid heterospecifics as mates. Contrary to these expectations, female spadefoot toads were more likely to choose heterospecific males when exposed to environmental conditions that favor hybridization. Indeed, those females with phenotypic characteristics for which hybridization is most favorable were most likely to switch from choosing conspecifics to heterospecifics. Moreover, environmentally dependent mate choice has evolved only in populations and species that risk engaging in, and can potentially benefit from, hybridization. Thus, when the benefits of mate choice vary, females may radically alter their mate selection in response to their own phenotype and their environment, even to the point of choosing males of other species. PMID:17991861

  2. Sustainable food consumption. Product choice or curtailment?

    PubMed

    Verain, Muriel C D; Dagevos, Hans; Antonides, Gerrit

    2015-08-01

    Food consumption is an important factor in shaping the sustainability of our food supply. The present paper empirically explores different types of sustainable food behaviors. A distinction between sustainable product choices and curtailment behavior has been investigated empirically and predictors of the two types of behavior have been identified. Respondents were classified into four segments based on their sustainable food behaviors: unsustainers, curtailers, product-oriented consumers, and sustainers. Significant differences between the segments were found with regard to food choice motives, personal and social norms, food involvement, subjective knowledge on sustainable food, ability to judge how sustainably a product has been produced and socio-demographics. It is concluded that distinguishing between behavioral strategies toward sustainable food consumption is important as consumer segments can be identified that differ both in their level of sustainable food consumption and in the type of behavior they employ. PMID:25913683

  3. Do framing effects reveal irrational choice?

    PubMed

    Mandel, David R

    2014-06-01

    Framing effects have long been viewed as compelling evidence of irrationality in human decision making, yet that view rests on the questionable assumption that numeric quantifiers used to convey the expected values of choice options are uniformly interpreted as exact values. Two experiments show that when the exactness of such quantifiers is made explicit by the experimenter, framing effects vanish. However, when the same quantifiers are given a lower bound (at least) meaning, the typical framing effect is found. A 3rd experiment confirmed that most people spontaneously interpret the quantifiers in standard framing tests as lower bounded and that their interpretations strongly moderate the framing effect. Notably, in each experiment, a significant majority of participants made rational choices, either choosing the option that maximized expected value (i.e., lives saved) or choosing consistently across frames when the options were of equal expected value. PMID:23978186

  4. Key policy choices in groundwater quality management

    SciTech Connect

    Batie, S.S.; Diebel, P.L. )

    1990-01-01

    The fundamental policy choice of who has the right to do what to whom is a pivotal issue of governance. Over the last few decades, the answer to that question has become more restrictive to those who own and use natural resources as inputs into production processes. Increasingly, the beneficiaries of new policy initiatives are those who desire higher protection of groundwater quality. With respect to groundwater management, policy design increasingly reflects such diverse interests as agriculturists, industrialists, homeowners, local government officials and state officials. Policy design is becoming complex, in part because of this diversity and in part because scientific uncertainty hampers informed policy design. No umbrella federal legislation exists for managing groundwater resources. EPA's role has been mainly an advisory one on groundwater issues. The difficulties and responsibilities of protecting groundwater thus remain with the states. For the near future, it is the states that will address key policy choices with respect to groundwater quality management issues.

  5. Making Healthy Choices Easier: Regulation versus Nudging.

    PubMed

    Hansen, Pelle Guldborg; Skov, Laurits Rohden; Skov, Katrine Lund

    2016-01-01

    In recent years, the nudge approach to behavior change has emerged from the behavioral sciences to challenge the traditional use of regulation in public health strategies to address modifiable individual-level behaviors related to the rise of noncommunicable diseases and their treatment. However, integration and testing of the nudge approach as part of more comprehensive public health strategies aimed at making healthy choices easier are being threatened by inadequate understandings of its scientific character, its relationship with regulation, and its ethical implications. This article reviews this character and its ethical implication with a special emphasis on the compatibility of nudging with traditional regulation, special domains of experience, and the need for a more nuanced approach to the ethical debate. The aim is to advance readers' understanding and give guidance to those who have considered working with or incorporating the nudge approach into programs or policies aimed at making healthful choices easier.

  6. 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.

  7. Shared decision making, paternalism and patient choice.

    PubMed

    Sandman, Lars; Munthe, Christian

    2010-03-01

    In patient centred care, shared decision making is a central feature and widely referred to as a norm for patient centred medical consultation. However, it is far from clear how to distinguish SDM from standard models and ideals for medical decision making, such as paternalism and patient choice, and e.g., whether paternalism and patient choice can involve a greater degree of the sort of sharing involved in SDM and still retain their essential features. In the article, different versions of SDM are explored, versions compatible with paternalism and patient choice as well as versions that go beyond these traditional decision making models. Whenever SDM is discussed or introduced it is of importance to be clear over which of these different versions are being pursued, since they connect to basic values and ideals of health care in different ways. It is further argued that we have reason to pursue versions of SDM involving, what is called, a high level dynamics in medical decision-making. This leaves four alternative models to choose between depending on how we balance between the values of patient best interest, patient autonomy, and an effective decision in terms of patient compliance or adherence: Shared Rational Deliberative Patient Choice, Shared Rational Deliberative Paternalism, Shared Rational Deliberative Joint Decision, and Professionally Driven Best Interest Compromise. In relation to these models it is argued that we ideally should use the Shared Rational Deliberative Joint Decision model. However, when the patient and professional fail to reach consensus we will have reason to pursue the Professionally Driven Best Interest Compromise model since this will best harmonise between the different values at stake: patient best interest, patient autonomy, patient adherence and a continued care relationship.

  8. INJECTION CHOICE FOR SPALLATION NEUTRON SOURCE RING.

    SciTech Connect

    WEI,J.; BEEBE-WANG,J.; BLASKIEWICZ,M.; BRODOWSKI,J.; FEDOTOV,A.; GARDNER,C.; LEE,Y.Y.; RAPARIA,D.; DANILOV,V.; HOLMES,J.; PRIOR,C.; REES,G.; MACHIDA,S.

    2001-06-18

    Injection is key in the low-loss design of high-intensity proton facilities like the Spallation Neutron Source (SNS). During the design of both the accumulator and the rapid-cycling-synchrotron version of the SNS, extensive comparison has been made to select injection scenarios that satisfy SNS's low-loss design criteria. This paper presents issues and considerations pertaining to the final choice of the SNS injection systems.

  9. From partner choice to equity - and beyond?

    PubMed

    Warneken, Felix

    2013-02-01

    Baumard et al. provide an intriguing model where morality emerges from the dynamics of partner choice in mutualistic interactions. I discuss evidence from human and nonhuman primates that supports the overall approach, but highlights a gap in explaining the human specificity of moral cognition. I suggest that an essential characteristic of human fairness is to override concerns about merit in favor of promoting the welfare in others who are needy.

  10. Rats exhibit reference-dependent choice behavior.

    PubMed

    Bhatti, Mehwish; Jang, Hyeran; Kralik, Jerald D; Jeong, Jaeseung

    2014-07-01

    Human preferences depend on whether a chosen outcome appears to be a loss or a gain compared with what had been expected, i.e., in comparison to a reference point. Because reference dependence has such a strong influence on human decision-making, it is important to uncover its origins, which will in turn help delineate the underlying mechanisms. It remains unknown whether rats use reference points in decision-making, and yet, the study of rats could help address the question of whether reference dependence is evolutionarily conserved among mammals and could provide a nonhuman animal model to investigate the neural mechanisms underlying this important cognitive process. The aim of the current study was to determine whether rats show reference-dependent choice behavior. We developed a novel paradigm by modifying the "T" maze by installing "pockets" to the left and right of the "T" stem that held reward pellets so rats would potentially develop reference values for each option prior to choice. We found that the rats were indeed sensitive to the way alternatives were presented. That is, they exhibited reference-dependent choice behavior by avoiding the choice option framed as a loss (e.g., having four reward pellets in the pocket, but receiving only one), at least under conditions with certain outcomes and clear differences between the reference and outcome quantities. Despite the small number of rats in this study, this species-level capacity suggests that reference dependence in general and loss aversion in particular may be conserved traits that evolved at or before the emergence of mammals.

  11. Opportunities for women through reproductive choice.

    PubMed

    McCauley, A P; Robey, B; Blanc, A K; Geller, J S

    1994-07-01

    Women around the world hope for the future--for better lives for themselves, education and prosperity for their children, and security for their families. A broad array of social and economic changes is necessary to overcome the poverty, lack of education, and limited control over their own lives that often keep women's hopes from coming true. But women can take an important step forward when they make their own reproductive choices--about marriage, sex, childbearing, and contraception.

  12. Model for understanding consumer textural food choice.

    PubMed

    Jeltema, Melissa; Beckley, Jacqueline; Vahalik, Jennifer

    2015-05-01

    The current paradigm for developing products that will match the marketing messaging is flawed because the drivers of product choice and satisfaction based on texture are misunderstood. Qualitative research across 10 years has led to the thesis explored in this research that individuals have a preferred way to manipulate food in their mouths (i.e., mouth behavior) and that this behavior is a major driver of food choice, satisfaction, and the desire to repurchase. Texture, which is currently thought to be a major driver of product choice, is a secondary factor, and is important only in that it supports the primary driver-mouth behavior. A model for mouth behavior is proposed and the qualitative research supporting the identification of different mouth behaviors is presented. The development of a trademarked typing tool for characterizing mouth behavior is described along with quantitative substantiation of the tool's ability to group individuals by mouth behavior. The use of these four groups to understand textural preferences and the implications for a variety of areas including product design and weight management are explored. PMID:25987995

  13. Honey bees selectively avoid difficult choices.

    PubMed

    Perry, Clint J; Barron, Andrew B

    2013-11-19

    Human decision-making strategies are strongly influenced by an awareness of certainty or uncertainty (a form of metacognition) to increase the chances of making a right choice. Humans seek more information and defer choosing when they realize they have insufficient information to make an accurate decision, but whether animals are aware of uncertainty is currently highly contentious. To explore this issue, we examined how honey bees (Apis mellifera) responded to a visual discrimination task that varied in difficulty between trials. Free-flying bees were rewarded for a correct choice, punished for an incorrect choice, or could avoid choosing by exiting the trial (opting out). Bees opted out more often on difficult trials, and opting out improved their proportion of successful trials. Bees could also transfer the concept of opting out to a novel task. Our data show that bees selectively avoid difficult tasks they lack the information to solve. This finding has been considered as evidence that nonhuman animals can assess the certainty of a predicted outcome, and bees' performance was comparable to that of primates in a similar paradigm. We discuss whether these behavioral results prove bees react to uncertainty or whether associative mechanisms can explain such findings. To better frame metacognition as an issue for neurobiological investigation, we propose a neurobiological hypothesis of uncertainty monitoring based on the known circuitry of the honey bee brain.

  14. Sensitivity, changeover responses, and choice in transition.

    PubMed

    Jiménez, Angel A; Aparicio, Carlos F

    2009-09-01

    Studies of choice in steady state have shown that sensitivity to reinforcement increases with increasing fixed-ratio changeover (FR CO) requirements. We assessed the generality of this finding with choice in transition. Food deliveries were programmed according to concurrent variable-interval (VI) schedules. Seven different VI pairs arranged ratios of food deliveries (left/right) of 27:1, 9:1, 3:1, 1:1, 1:3, 1:9, and 1:27 at a constant overall rate across components. Within sessions, all seven ratios were presented in random order. Each component lasted for 10 food deliveries; components were separated by 60-s blackouts. A changeover lever required 1, 2, 4, 8, 16, 32, and 64 responses to alternate between two main levers. Redeterminations to all FR COs, but 64 responses, were obtained in descending order. Choice adjusted rapidly to rapid changes in the reinforcer ratio, tracking the lever associated with the highest probability of reinforcer. Sensitivity to reinforcement increased with increasing FR CO, replicating the negatively accelerated function found in our earlier study. With successive reinforcers in components, however, sensitivity reached asymptote values sooner with the largest (8, 16, and 32 responses), than with the smallest (1, 2, and 4 responses), FR CO requirements.

  15. Putting Health Back Into Health Insurance Choice.

    PubMed

    Atanasov, Pavel; Baker, Tom

    2014-08-01

    What are the barriers to voluntary take-up of high-deductible plans? We address this question using a large-scale employer survey conducted after an open-enrollment period in which a new high-deductible plan was first introduced. Only 3% of the employees chose this plan, despite the respondents' recognition of its financial advantages. Employees who believed that the high-deductible plan provided access to top physicians in the area were three times more likely to choose it than employees who did not share this belief. A framed field experiment using a similar choice menu showed that displaying additional financial information did not increase high-deductible plan take-up. However, when plans were presented as identical except for the deductible, respondents were highly likely to choose the high-deductible plan, especially in a two-way choice. These results suggest that informing plan choosers about high-deductible plans' health access provisions may affect choice more strongly than focusing on their financial advantages. PMID:24811934

  16. Air Cargo Transportation Route Choice Analysis

    NASA Technical Reports Server (NTRS)

    Obashi, Hiroshi; Kim, Tae-Seung; Oum, Tae Hoon

    2003-01-01

    Using a unique feature of air cargo transshipment data in the Northeast Asian region, this paper identifies the critical factors that determine the transshipment route choice. Taking advantage of the variations in the transport characteristics in each origin-destination airports pair, the paper uses a discrete choice model to describe the transshipping route choice decision made by an agent (i.e., freight forwarder, consolidator, and large shipper). The analysis incorporates two major factors, monetary cost (such as line-haul cost and landing fee) and time cost (i.e., aircraft turnaround time, including loading and unloading time, custom clearance time, and expected scheduled delay), along with other controls. The estimation method considers the presence of unobserved attributes, and corrects for resulting endogeneity by use of appropriate instrumental variables. Estimation results find that transshipment volumes are more sensitive to time cost, and that the reduction in aircraft turnaround time by 1 hour would be worth the increase in airport charges by more than $1000. Simulation exercises measures the impacts of alternative policy scenarios for a Korean airport, which has recently declared their intention to be a future regional hub in the Northeast Asian region. The results suggest that reducing aircraft turnaround time at the airport be an effective strategy, rather than subsidizing to reduce airport charges.

  17. Model for understanding consumer textural food choice

    PubMed Central

    Jeltema, Melissa; Beckley, Jacqueline; Vahalik, Jennifer

    2015-01-01

    The current paradigm for developing products that will match the marketing messaging is flawed because the drivers of product choice and satisfaction based on texture are misunderstood. Qualitative research across 10 years has led to the thesis explored in this research that individuals have a preferred way to manipulate food in their mouths (i.e., mouth behavior) and that this behavior is a major driver of food choice, satisfaction, and the desire to repurchase. Texture, which is currently thought to be a major driver of product choice, is a secondary factor, and is important only in that it supports the primary driver—mouth behavior. A model for mouth behavior is proposed and the qualitative research supporting the identification of different mouth behaviors is presented. The development of a trademarked typing tool for characterizing mouth behavior is described along with quantitative substantiation of the tool's ability to group individuals by mouth behavior. The use of these four groups to understand textural preferences and the implications for a variety of areas including product design and weight management are explored. PMID:25987995

  18. Chemoreception, symmetry and mate choice in lizards.

    PubMed Central

    Martín, J; López, P

    2000-01-01

    Research on fluctuating asymmetry (FA)-mediated sexual selection has focused almost exclusively on visual signals and ignored chemical communication despite the fact that many species rely on chemical signals for attracting mates. Female mate choice based on visual traits appears to be rare in lizards. However, the femoral glands of male lizards produce pheromones which might transmit chemical information about an individual's developmental stability. Therefore, we hypothesized that mate choice may be based on chemical cues. We analysed the effect of the developmental stability levels of males on the attractiveness of males' scents to females in a laboratory experiment with the lizard Lacerta monticola. When we offered two males of similar body size, females preferentially associated with the scents of males with low FA in their femoral pores and also with the scents of males with a higher number of femoral pores. This suggested that the females were able to discriminate the FA of the males by chemical signals alone and that the females preferred to be in areas marked by males of high quality, thus increasing their opportunities of mating with males of high quality. We suggest that the quality and/or amount of male pheromones could communicate the heritable genetic quality of a male to the female and thereby serve as the basis for adaptive female choice in lizards. PMID:10972119

  19. Arbitration between controlled and impulsive choices.

    PubMed

    Economides, M; Guitart-Masip, M; Kurth-Nelson, Z; Dolan, R J

    2015-04-01

    The impulse to act for immediate reward often conflicts with more deliberate evaluations that support long-term benefit. The neural architecture that negotiates this conflict remains unclear. One account proposes a single neural circuit that evaluates both immediate and delayed outcomes, while another outlines separate impulsive and patient systems that compete for behavioral control. Here we designed a task in which a complex payout structure divorces the immediate value of acting from the overall long-term value, within the same outcome modality. Using model-based fMRI in humans, we demonstrate separate neural representations of immediate and long-term values, with the former tracked in the anterior caudate (AC) and the latter in the ventromedial prefrontal cortex (vmPFC). Crucially, when subjects' choices were compatible with long-run consequences, value signals in AC were down-weighted and those in vmPFC were enhanced, while the opposite occurred when choice was impulsive. Thus, our data implicate a trade-off in value representation between AC and vmPFC as underlying controlled versus impulsive choice.

  20. Sensitivity, changeover responses, and choice in transition.

    PubMed

    Jiménez, Angel A; Aparicio, Carlos F

    2009-09-01

    Studies of choice in steady state have shown that sensitivity to reinforcement increases with increasing fixed-ratio changeover (FR CO) requirements. We assessed the generality of this finding with choice in transition. Food deliveries were programmed according to concurrent variable-interval (VI) schedules. Seven different VI pairs arranged ratios of food deliveries (left/right) of 27:1, 9:1, 3:1, 1:1, 1:3, 1:9, and 1:27 at a constant overall rate across components. Within sessions, all seven ratios were presented in random order. Each component lasted for 10 food deliveries; components were separated by 60-s blackouts. A changeover lever required 1, 2, 4, 8, 16, 32, and 64 responses to alternate between two main levers. Redeterminations to all FR COs, but 64 responses, were obtained in descending order. Choice adjusted rapidly to rapid changes in the reinforcer ratio, tracking the lever associated with the highest probability of reinforcer. Sensitivity to reinforcement increased with increasing FR CO, replicating the negatively accelerated function found in our earlier study. With successive reinforcers in components, however, sensitivity reached asymptote values sooner with the largest (8, 16, and 32 responses), than with the smallest (1, 2, and 4 responses), FR CO requirements. PMID:19615608

  1. 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.

  2. 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. PMID:26892010

  3. A cumulative decision model for three-alternative choice in concurrent chains.

    PubMed

    Grace, Randolph C; McLean, Anthony P

    2016-07-01

    Traditional models for choice in the concurrent-chains procedure have assumed that terminal-link stimuli acquire value as conditioned reinforcers, and that 2-alternative choice provides a measure of relative value according to the matching law. By contrast, the cumulative decision model (CDM; Christensen & Grace, 2010) explains choice as the aggregate effect of comparing delays to a criterion on initial-link responding, not conditioned reinforcement. Here we test whether the CDM can account for choice in 3-alternative concurrent-chains (3ACC) and compare it with the hyperbolic value-added model (HVA; Mazur, 2001), which assumes that choice depends on the increase in conditioned reinforcement value signaled by terminal-link stimuli and has been successful in previous 3ACC research (Mazur, 2000). In Experiment 1, 4 pigeons responded in 3ACC in which the terminal links were fixed-interval schedules, and parameter estimates from fits of CDM and HVA were used to calculate predictions for conditions with variable-interval terminal links. The predictions of CDM were more accurate than those of HVA. In Experiment 2, 7 pigeons responded in 3ACC in which the terminal links were fixed-interval schedules. Although both models described the data well, residuals from HVA fits showed a systematic pattern predicted by CDM, characterized by a third-order polynomial with a negative cubic coefficient. Finally, we conducted a residual meta-analysis (Sutton, Grace, McLean, & Baum, 2008) of data from prior 3ACC studies. HVA residuals showed the same negative cubic pattern as in Experiment 2, whereas no systematic pattern was found in the CDM residuals. Overall, results support the CDM and suggest that the same principles which describe binary choice in concurrent chains generalize without modification to 3-alternative choice. (PsycINFO Database Record PMID:27379716

  4. 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.

  5. Modelling the evolution of female choice strategies under inbreeding conditions.

    PubMed

    Reinhold, Klaus

    2002-11-01

    Recently, many mate choice studies have discussed the role of genetic compatibility and inbreeding for the evolution of mate choice. With population genetic simulations I compared the potential advantage of three different female choice strategies under inbreeding conditions. Females were assumed to benefit indirectly via a preference for (i) complementary males, (ii) males with few detrimental mutations, and (iii) non-inbred males. Probably related to the reduced inbreeding depression in offspring of choosy females, the choice-allele increased for all three strategies. However, the advantage of the strategies differed widely. Choice of males with fewer mutations provided a comparatively large advantage, choice of complementary males led to a reasonable advantage, and choice of non-inbred males only resulted in a minor advantage of female choice. My results show that complementary mate choice can be almost as beneficial as conventional good-genes choice of mates with lower genetic load. Compared to the two other mate choice strategies, choice of non-inbred males is less likely to contribute to the evolution of costly mate choice. The results of a recent study showing that female sticklebacks prefer males with a larger number of MHC-loci is thus unlikely to be related to an indirect benefit of choosing non-inbred males. PMID:12555777

  6. Determinants of journal choice among Nigerian medics

    PubMed Central

    Olusegun, Nwhator Solomon; Olayinka, Agbaje Maarufah; Modupe, Soroye; Ikenna, Isiekwe Gerald

    2015-01-01

    Introduction Despite the well-known maxim "publish or perish" among academicians, productivity remains low in Nigeria. There are barriers to academic writing which must be identified and addressed. Even after addressing those barriers, authors are faced with another dilemma-where to publish. It was the concern of the authors to evaluate perceived barriers to academic writing and the determinants of journal choice among Nigerian academics. They also attempted to evaluate the determinants of journal choice and perceived barriers to academic writing among Nigerian academicians. Respondents were academicians used in the context of this study to mean anyone involved in academic writing. Such persons must have written and published at least one paper in a peer-reviewed journal in the preceding year to be included in the survey. An online-based self-administered questionnaire. Methods An online structured and self-administered questionnaire-based cross sectional survey of Nigerian medical academicians was conducted over a period of one year using a Google-powered questionnaire. The questionnaire assessed the determinants of journal choice, perceived barriers to publications, number of publications in the preceding year as a measure of academic productivity and the highest publication fee authors were willing to pay. Results Of the over 500 email request sent, a total of 200 academicians responded (response rate of 40%). The male and female distribution was 120 and 80 respectively. The highest number of respondents were lecturer 1 and senior lecturers (or junior faculty) (69.5%) however the senior faculty had the higher number of publications in the preceding year. Indexing (35.5%) was the most important determinant of journal choice whilst ease of submission (2.1%) was the least. Unfriendly environment (46%) was the most perceived barrier to publication. Though, majority (88.5%) of the respondents were willing to pay up $300 as publication fees, twice as many junior

  7. A numerical method for solving a stochastic inverse problem for parameters.

    PubMed

    Butler, T; Estep, D

    2013-02-01

    We review recent work (Briedt et al., 2011., 2012) on a new approach to the formulation and solution of the stochastic inverse parameter determination problem, i.e. determine the random variation of input parameters to a map that matches specified random variation in the output of the map, and then apply the various aspects of this method to the interesting Brusselator model. In this approach, the problem is formulated as an inverse problem for an integral equation using the Law of Total Probability. The solution method employs two steps: (1) we construct a systematic method for approximating set-valued inverse solutions and (2) we construct a computational approach to compute a measure-theoretic approximation of the probability measure on the input space imparted by the approximate set-valued inverse that solves the inverse problem. In addition to convergence analysis, we carry out an a posteriori error analysis on the computed probability distribution that takes into account all sources of stochastic and deterministic error. PMID:24347806

  8. A numerical method for solving a stochastic inverse problem for parameters

    PubMed Central

    Butler, T.; Estep, D.

    2013-01-01

    We review recent work (Briedt et al., 2011., 2012) on a new approach to the formulation and solution of the stochastic inverse parameter determination problem, i.e. determine the random variation of input parameters to a map that matches specified random variation in the output of the map, and then apply the various aspects of this method to the interesting Brusselator model. In this approach, the problem is formulated as an inverse problem for an integral equation using the Law of Total Probability. The solution method employs two steps: (1) we construct a systematic method for approximating set-valued inverse solutions and (2) we construct a computational approach to compute a measure-theoretic approximation of the probability measure on the input space imparted by the approximate set-valued inverse that solves the inverse problem. In addition to convergence analysis, we carry out an a posteriori error analysis on the computed probability distribution that takes into account all sources of stochastic and deterministic error. PMID:24347806

  9. Prospects of Brand Choice Behavior Research from Cognitive Perspective

    NASA Astrophysics Data System (ADS)

    Wang, Xiaohui; Lin, Lin

    The article reviews relevant literature at home and abroad on consumer brand choice behavior and summarizes the study evolution of consumer brand choice behavior, and puts forward view on relevant research prospects from cognitive perspective in this field.

  10. Prostate Cancer Treatments: Different Choices for Different Men

    MedlinePlus

    ... news/fullstory_160953.html Prostate Cancer Treatments: Different Choices for Different Men Survival rates are all high, ... prove that "watchful waiting" is always the best choice. Men who were otherwise largely healthy and chose ...

  11. 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.

  12. 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

  13. Asymmetry of reinforcement and punishment in human choice.

    PubMed

    Rasmussen, Erin B; Newland, M Christopher

    2008-03-01

    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

  14. Choice of regularization weight in basis pursuit reflectivity inversion

    NASA Astrophysics Data System (ADS)

    Sen, Mrinal K.; Biswas, Reetam

    2015-02-01

    Seismic inverse problem of estimating P- and S-wave reflectivity from seismic traces has recently been revisited using a basis pursuit denoising inversion (BPI) approach. The BPI uses a wedge dictionary to define model constraints, which has been successful in resolving thin beds. Here we address two fundamental problems associated with BPI, namely, the uniqueness of the estimate and the choice of regularization weight λ to be used in the model norm. We investigated these using very fast simulated re-annealing (VFSR) and gradient projection sparse reconstruction (GPSR) approaches. For a synthetic model with two reflectors separated by one time sample, we are able to demonstrate convergence of VFSR to the true model with different random starting models. Two numerical approaches to estimating the regularization weight were investigated. One uses λ as a hyper-parameter and the other uses this as a temperature-like annealing parameter. In both cases, we were able to obtain λ fairly rapidly. Finally, an analytic formula for λ that is iteration adaptive was also implemented. Successful applications of our approach to synthetic and field data demonstrate validity and robustness.

  15. Asymmetry of reinforcement and punishment in human choice.

    PubMed

    Rasmussen, Erin B; Newland, M Christopher

    2008-03-01

    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.

  16. Parameters of Technological Growth

    ERIC Educational Resources Information Center

    Starr, Chauncey; Rudman, Richard

    1973-01-01

    Examines the factors involved in technological growth and identifies the key parameters as societal resources and societal expectations. Concludes that quality of life can only be maintained by reducing population growth, since this parameter is the product of material levels, overcrowding, food, and pollution. (JR)

  17. 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).

  18. Error estimates and specification parameters for functional renormalization

    SciTech Connect

    Schnoerr, David; Boettcher, Igor; Pawlowski, Jan M.; Wetterich, Christof

    2013-07-15

    We present a strategy for estimating the error of truncated functional flow equations. While the basic functional renormalization group equation is exact, approximated solutions by means of truncations do not only depend on the choice of the retained information, but also on the precise definition of the truncation. Therefore, results depend on specification parameters that can be used to quantify the error of a given truncation. We demonstrate this for the BCS–BEC crossover in ultracold atoms. Within a simple truncation the precise definition of the frequency dependence of the truncated propagator affects the results, indicating a shortcoming of the choice of a frequency independent cutoff function.

  19. Variation in male mate choice in Drosophila melanogaster.

    PubMed

    Edward, Dominic A; Chapman, Tracey

    2013-01-01

    Male mate choice has been reported in the fruit fly, Drosophila melanogaster, even though males of this species were previously thought to maximise their fitness by mating with all available females. To understand the evolution of male mate choice it is important to understand variation in male mating preferences. Two studies, using different stock populations and different methods, have reported contrasting patterns of variation in male mate choice in D. melanogaster. Two possible explanations are that there are evolved differences in each stock population or that the methods used to measure choice could have biased the results. We investigated these hypotheses here by repeating the methods used in one study in which variable male mate choice was found, using the stock population from the other study in which choice was not variable. The results showed a significant resource-independent male preference for less fecund, smaller females, which contrasts with previous observations of male mate choice. This indicates that different selection pressures between populations have resulted in evolved differences in the expression of male mate choice. It also reveals phenotypic plasticity in male mate choice in response to cues encountered in each choice environment. The results highlight the importance of variation in male mate choice, and of identifying mechanisms in order to understand the evolution of mate choice under varying ecological conditions.

  20. 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…