BACKGROUND Previous studies indicate that the design of streets and sidewalks can influence physical activity among residents. Park features also influence park use and park-based physical activity. Although individuals can walk on streets and sidewalks, walking loops in parks offer a setting to walk in nature and to avoid interruptions from traffic. OBJECTIVES Here we describe the use of wal...

This is the comment to the preprints by G. Ossola and A. Sirlin, hep-ph/0305050, and E.Kh. Akhmedov, hep-th/0204048, who discussed different regularization schemes for calculations of the vacuum energy stored in the zero-point motion of fundamental fields. We show that the contribution of the fermionic and bosonic fields to the energy of the vacuum depends on the physical realization of the vac...

All beams are a superposition of plane waves, which carry linear momentum in the direction of propagation with no net azimuthal component. However, plane waves incident on a hologram can produce a vortex beam carrying orbital angular momentum that seems to require an azimuthal linear momentum, which presents a paradox. We resolve this by showing that the azimuthal momentum is not a true linear ...

In this work we use models of molecular clouds (MC), and non-LTE radiative transfer calculations, to obtain a theoretical calibration of the relation between LTE CO column density and true column density in MCs. The cloud models consist of 3 dimensional grids of density and velocity fields obtained as solutions of the compressible magneto-hydrodynamic equations in a 128 periodic grid in both th...

A given density matrix may be represented in many ways as a mixture of pure states. We show how any density matrix may be realized as a uniform ensemble. It has been conjectured that one may realize all probability distributions that are majorized by the vector of eigenvalues of the density matrix. We show that if the states in the ensemble are assumed to be distinct then it is not true, but a ...

The paper proposes a new estimating algorithm for linear parameter varying systems with slowly time-varying parameters when the rate of change of individual parameters is different. It introduces a true probability density function, describing ideally the behaviour of parameters. However, as it is unknown, we search for its best approximation. A convex combination of point estimates, defined by...

In this work we use models of molecular clouds (MC), and non-LTE radiative transfer calculations, to obtain a theoretical calibration of the relation between LTE CO column density and true column density in MCs. The cloud models consist of 3 dimensional grids of density and velocity fields obtained as solutions of the compressible magneto-hydrodynamic equations in a 128 periodic grid in both th...

Likelihood-based cross-validation is a statistical tool for selecting a density estimate based on n i.i.d. observations from the true density among a collection of candidate density estimators. General examples are the selection of a model indexing a maximum likelihood estimator, and the selection of a bandwidth indexing a nonparametric (e.g. kernel) density estimator. In this article, we estab...