237 research outputs found
Oriënterend bodemonderzoek van de terreinen van de samenwerkende vennootschap voor productie van elektriciteit (SPE NV) gelegen te Gent, Kattenberg
On symmetries of Chern-Simons and BF topological theories
We describe constructing solutions of the field equations of Chern-Simons and
topological BF theories in terms of deformation theory of locally constant
(flat) bundles. Maps of flat connections into one another (dressing
transformations) are considered. A method of calculating (nonlocal) dressing
symmetries in Chern-Simons and topological BF theories is formulated
Homogeneous variational problems: a minicourse
A Finsler geometry may be understood as a homogeneous variational problem,
where the Finsler function is the Lagrangian. The extremals in Finsler geometry
are curves, but in more general variational problems we might consider extremal
submanifolds of dimension . In this minicourse we discuss these problems
from a geometric point of view.Comment: This paper is a written-up version of the major part of a minicourse
given at the sixth Bilateral Workshop on Differential Geometry and its
Applications, held in Ostrava in May 201
Oriënterend bodemonderzoek van de terreinen van de samenwerkende vennootschap voor productie van elektriciteit (SPE NV) gelegen te Gent, Blaarmeersen
Rapport over het aanvullend oriënterend bodemonderzoek van het terrein van Pentagon Plastics, gelegen te Wakken
Asymptotic normality of the Parzen-Rosenblatt density estimator for strongly mixing random fields
We prove the asymptotic normality of the kernel density estimator (introduced
by Rosenblatt (1956) and Parzen (1962)) in the context of stationary strongly
mixing random fields. Our approach is based on the Lindeberg's method rather
than on Bernstein's small-block-large-block technique and coupling arguments
widely used in previous works on nonparametric estimation for spatial
processes. Our method allows us to consider only minimal conditions on the
bandwidth parameter and provides a simple criterion on the (non-uniform) strong
mixing coefficients which do not depend on the bandwith.Comment: 16 page
Symmetries of Helmholtz forms and globally variational dynamical forms
Invariance properties of classes in the variational sequence suggested to
Krupka et al. the idea that there should exist a close correspondence between
the notions of variationality of a differential form and invariance of its
exterior derivative. It was shown by them that the invariance of a closed
Helmholtz form of a dynamical form is equivalent with local variationality of
the Lie derivative of the dynamical form, so that the latter is locally the
Euler--Lagrange form of a Lagrangian. We show that the corresponding local
system of Euler--Lagrange forms is variationally equivalent to a global
Euler--Lagrange form.Comment: Presented at QTS7 - Quantum Theory and Symmetries VII, Prague
7-13/08/201
Adaptive density estimation for stationary processes
We propose an algorithm to estimate the common density of a stationary
process . We suppose that the process is either or
-mixing. We provide a model selection procedure based on a generalization
of Mallows' and we prove oracle inequalities for the selected estimator
under a few prior assumptions on the collection of models and on the mixing
coefficients. We prove that our estimator is adaptive over a class of Besov
spaces, namely, we prove that it achieves the same rates of convergence as in
the i.i.d framework
Maternal-child co-participation in physical activity-related behaviours: prevalence and cross-sectional associations with mothers and children\u27s objectively assessed physical activity levels
BACKGROUND: Co-participation in physical activity may be a useful strategy for increasing physical activity in mothers and their young children, yet little empirical evidence exists on this topic for young families. This study aimed to identify the prevalence of mother-child co-participation in physical activity and examine the association between co-participatory behaviours and objectively-assessed physical activity in young children and their mothers. METHODS: One-hundred twenty-three 4-6 year-old children and their mothers were recruited from preschools in Belgium between November 2010 and January 2011. Mothers completed a questionnaire assessing the frequency of co-participation in five activities. Both mothers and children wore ActiGraph GT1M accelerometers concurrently for 7 days to assess the time spent in moderate-to vigorous-intensity physical activity (MVPA) and light- to vigorous-intensity physical activity (LMVPA). Descriptive statistics (means, frequencies) were used to determine the prevalence of co-participation. Separate multiple linear regression analyses examined the association between co-participation and mothers\u27 and children\u27s physical activity on weekdays and weekends. RESULTS: Most mothers reported infrequent co-participation in physical activities with their children. On weekdays, walking or cycling for short trips was positively associated with children\u27s MVPA while attending a park or similar more than once per week was negatively associated with children\u27s MVPA and LMVPA. Going to an indoor play centre together once or more per week was negatively associated with mother\u27s LMVPA. On weekends, walking or cycling with their child in their free time was positively associated with both children\u27s and mothers\u27 MVPA and childrens\u27 LMVPA. Going to an indoor play centre together 1-3 times/month was negatively associated with children\u27s weekend MVPA. CONCLUSIONS: Reported rates of co-participation in mothers and their preschool children were low. The association with maternal and child physical activity may be dependent on the co-participatory behaviour assessed and may differ between weekday and weekends. Promoting walking and cycling together during leisure time may be an effective strategy to increase both preschool children\u27s and mothers\u27 MVPA
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