1,661 research outputs found
Spatial models generated by nested stochastic partial differential equations, with an application to global ozone mapping
A new class of stochastic field models is constructed using nested stochastic
partial differential equations (SPDEs). The model class is computationally
efficient, applicable to data on general smooth manifolds, and includes both
the Gaussian Mat\'{e}rn fields and a wide family of fields with oscillating
covariance functions. Nonstationary covariance models are obtained by spatially
varying the parameters in the SPDEs, and the model parameters are estimated
using direct numerical optimization, which is more efficient than standard
Markov Chain Monte Carlo procedures. The model class is used to estimate daily
ozone maps using a large data set of spatially irregular global total column
ozone data.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS383 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Exogenous Forces in the Development of Our Banking System
A new method to optimize with orthonormal constraints is described, where a particular composition of plane (Givens) rotations is used to parameterize decision variables in terms of angles. It is showed that this parameterization is complete and that any orthonormal k-by-nmatrix can be derived to a set of no more than kn-k(k+1) angles. The technique is applied to the emph {feature extraction problem} where a linear subspace is optimized with respect to non-linear objective functions. The Optimal Discriminative Projection (ODP) algorithm is described. ODP is a data compression or feature extraction algorithm that combines powerful model optimization with regularization to avoid over training. The ODP is used primarily for classification problems
Quantifying the uncertainty of contour maps
Contour maps are widely used to display estimates of spatial fields. Instead
of showing the estimated field, a contour map only shows a fixed number of
contour lines for different levels. However, despite the ubiquitous use of
these maps, the uncertainty associated with them has been given a surprisingly
small amount of attention. We derive measures of the statistical uncertainty,
or quality, of contour maps, and use these to decide an appropriate number of
contour lines, that relates to the uncertainty in the estimated spatial field.
For practical use in geostatistics and medical imaging, computational methods
are constructed, that can be applied to Gaussian Markov random fields, and in
particular be used in combination with integrated nested Laplace approximations
for latent Gaussian models. The methods are demonstrated on simulated data and
an application to temperature estimation is presented
Obscenity and the Mail: A Study of Administrative Restraint
This paper shows how 3-dimensional interactive visualization can be used as a tool in system identification. Non-linear or time-dependent dynamics often leave a significant residual with linear, time-invariant models. The structure of this residual is decisive for the subsequent modelling, and by using advanced visualization techniques, the modeller may gain a deeper insight into this structure than can be obtained by standard correlation analysis
International space law and norms: an approach for assessing compliance
The number and types of space activities and space actors continue to increase, posing new and unique challenges for space governance and policy. Presently, a comprehensive, periodic, and systematic measure of statesâ efforts to comply with existing international space law and norms does not exist, suggesting a critical need to ensure robust and informed policymaking as space activities and actors increase. The evidence-based policymaking and programming movement, alongside the rise of ratings and rankings research, suggest the utility of such an assessment to informing policymaking and identifying compliance or partial or noncompliance of spacefaring countries. Numerous ratings and rankings assessments measure country-level trends across various sectors, including but not limited to business, democracy, economics, human rights, governance, and prosperity. However, none currently measure the behaviour and policies of countries regarding the exploration and use of outer space. An annual space report, published by the Space Security Index, does provide an overview of space activities and trends according to various thematic areas, but neither provides a historical nor baseline comparison of statesâ behaviour. This dissertation endeavours to propose a set of criteria, grounded in international space treaties and United Nations-level principles, resolutions, and guidelines, for which space policy stakeholders can apply to countries and develop a comparative understanding of their levels of compliance with binding international space law and non-binding space norms
Using Self-Experimentation and Single-Subject Methodology to Promote Critical Thinking
Critical thinking is often absent from classroom endeavor because it is hard to define (Gelder, 2005) or is difficult to assess (Bissell & Lemons, 2006). Critical thinking is defined as application, analysis, synthesis, and evaluation (Browne & Minnick, 2005). This paper shows how self-experimentation and single-subject methodology can be used to promote many levels of critical thinking in an Applied Behavior Analysis course. Two classroom assignment examples of this process and a grading rubric are provided
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