Nonparametric Growth Curve Model with Local Linear Approximation

The growth curve model has been developed for longitudinal data, and its time trend is usually described by polynomials. However, it is difficult to interpret each coefficient of the polynomials with higher degrees, even when the number of repetitions is sufficiently large. We propose herein an alternative growth curve model having time-varying coefficients.     

Readouts for echo-state networks built using locally regularized orthogonal forward regression

Echo state network (ESN) is viewed as a temporal expansion which naturally give rise to regressors of various relevance to a teacher output. We illustrate that often only a certain amount of the generated echo-regressors effectively explain the teacher output and we propose to determine the importance of the echo-regressors by a joint calculation of the individual variance contributions and Bayesian relevance using the locally regularized orthogonal forward regression (LROFR). This information can be advantageously used in a variety of ways for an analysis of an ESN structure. We present a locally regularized linear readout built using LROFR. The readout may have a smaller dimensionality than the ESN model itself, and improves robustness and accuracy of an ESN. Its main advantage is ability to determine what type of an additional readout is suitable for a task at hand. Comparison with PCA is provided too. We also propose a radial basis function (RBF) readout built using LROFR, since flexibility of the linear readout has limitations and might be insufficient for complex tasks. Its excellent generalization abilities make it a viable alternative to feed-forward neural networks or relevance-vector-machines. For cases where more temporal capacity is required we propose well studied delay&sum readout.     

Variable selection via the weighted group lasso for factor analysis models

We consider the problem of selecting variables in factor analysis models. The $L_1$ regularization procedure is introduced to perform an automatic variable selection. In the factor analysis model, each variable is controlled by multiple factors when there are more than one underlying factor. We treat parameters corresponding to the multiple factors as grouped parameters, and then apply the group lasso. Furthermore, the weight of the group lasso penalty is modified to obtain appropriate estimates and improve the performance of variable selection. Crucial issues in this modeling procedure include the selection of the number of factors and a regularization parameter. Choosing these parameters can be viewed as a model selection and evaluation problem. We derive a model selection criterion for evaluating the factor analysis model via the weighted group lasso. Monte Carlo simulations are conducted to investigate the effectiveness of the proposed procedure. A real data example is also given to illustrate our procedure. The Canadian Journal of Statistics 40: 345–361; 2012 © 2012 Statistical Society of Canada     

Socio-material arrangements of impoverished youth in Japan: historical and critical perspectives on neoliberalization

In the past decade, in Japan, a new light has been cast on youth poverty in the context of the middle-class impoverishment caused by the advance of neoliberalization. Thus, the socio-material arrangements, that is, the configuration of people and artifacts pertaining to poor Japanese children, was explored. The authors conducted a field survey in Tokyo’s Adachi Ward, where poverty and the problems it brings have become more serious, and then analyzed that data. In the analysis, we introduced a historical viewpoint to understand the changes in the socio-material arrangements of poor youth that have been brought about by neoliberalization.     

The dynamic transformation of political systems through social contract: a game theoretic approach

 We consider how the political system of the state evolves in the process of economic development. We present a dynamic public goods economy with non-overlapping generations, which confronts the free-rider problem without the state. In each generation, individuals enter under the unanimous rule a social contract of the political system, either monarchy or democracy, and then attempt to establish the state under the contracted political system. If the state is established, it provides public goods by enforcing tax on its members. Our game theoretic analysis shows: (i) the state can be established if and only if social productivity in terms of the capital stock of public goods is lower than a critical level; (ii) individuals choose democracy if social productivity is sufficiently high, while monarchy may be chosen if it is not; (iii) social productivity stochastically converges to the critical level over generations; and (iv) a simulation result shows several transformation patterns of political systems. Received: 21 June 1994/Accepted: 7 November 1995     

Creating facial animation of characters via MoCap data

We consider the problem of generating 3D facial animation of characters. An efficient procedure is realized by using the motion capture data (MoCap data), which is obtained by tracking the facial markers from an actor/actress. In some cases of artistic animation, the MoCap actor/actress and the 3D character facial animation show different expressions. For example, from the original facial MoCap data of speaking, a user would like to create the character facial animation of speaking with a smirk. In this paper, we propose a new easy-to-use system for making character facial animation via MoCap data. Our system is based on the interpolation: once the character facial expressions of the starting and the ending frames are given, the intermediate frames are automatically generated by information from the MoCap data. The interpolation procedure consists of three stages. First, the time axis of animation is divided into several intervals by the fused lasso signal approximator. In the second stage, we use the kernel k-means clustering to obtain control points. Finally, the interpolation is realized by using the control points. The user can easily create a wide variety of 3D character facial expressions by changing the control points.     

The Risk Screening for Indoor Air Pollution Chemicals in Japan

In recent years, public health problems caused by indoor air pollution have been drawing strong public concern in Japan. After conducting extensive exposure assessment, governmental agencies have taken effective measures to solve the problem; for instance, "Guidelines for indoor air quality (IAQ)" of 13 chemicals, for example, formaldehyde, toluene, and xylene, has been established. Thousands of chemicals have been identified in the indoor environment. Priority rating of those chemicals, however, was not based on the health risk level. We developed a risk-screening scheme for indoor air pollution chemicals and analyzed the current status of the risk levels of those chemicals in Japan. We researched scientific knowledge of health hazards and exposure surveys of indoor air pollution chemicals in Japan, and classified those chemicals based on the health risk level estimated from the scheme. The risk levels of 93 chemicals were characterized and six chemicals (formaldehyde, acrolein, 1,4-dichlorobenzene, benzene, tetrachloroethylene, and benzo(a)pyrene) were classified in the highest risk category.     

Second‐pillar pensions in Central and Eastern Europe: Payment constraints and exit options

During 1998–2007, a majority of Central and Eastern European (CEE) governments enacted laws obligating workers to save for retirement in privately managed individual accounts. The governments funded these accounts with a portion of public pension revenues, thus creating or increasing deficits in public systems. After the onset of the global financial and economic crisis (2008), most CEE governments reduced these funding diversions and scaled back the accounts. Now, a decade after the crisis, this article examines the benefits that the accounts are beginning to pay retiring workers. In general, these benefits are shown to be disadvantageous compared with public pensions. Some pay lump sums in lieu of regular monthly benefits, most fail to adjust pensions regularly for inflation, and some pay women less than men with equal account balances. In several countries, pensioners with individual accounts receive lower benefits than those without them. To enable retiring workers to avoid these disadvantages, several CEE governments have allowed them to refund their account balances and receive full public pensions. Yet while this strategy diffuses worker dissatisfaction, it also places strains on public pension finance. To assist second‐pillar account holders without weakening public pensions, governments should consider making private pension savings voluntary and financing these schemes independently of public pensions – i.e. by worker and employer contributions and, possibly, direct state support.