In animals, the interface between organism and environment is constituted by the epithelium. In plants, the exchange of nutrients and signals between root and soil is crucial for their survival, but the cellular mechanisms underlying the epithelium-like function and specific localization of proteins to the root surface have not been identified. Here we analyze the mechanism of polar delivery to...

In this paper, we first give a characterization of sub-topical functions with respect to their lower level sets and epigraph. Next, by using two different classes of elementary functions, we present a characterization of sub-topical functions with respect to their polar functions, and investigate the relation between polar functions and support sets of this class of functions. Finally, we obtai...

Polar organisms must cope with an environment that periodically lacks the strongest time-giver, or zeitgeber, of circadian organization-robust, cyclical oscillations between light and darkness. We review the factors influencing the persistence of circadian rhythms in polar vertebrates when the light-dark cycle is absent, the likely mechanisms of entrainment that allow some polar vertebrates to ...

Real-time control architectures for active vision impose strong constraints on the computational complexity of image processing algorithms. In many cases, fast and reactive visual routines are achieved by drastically reducing the image size, at the cost of degrading the accuracy of the algorithms. The non-uniform sampling of the images, such as the log-polar mapping, is an eecient way of reduci...

BACKGROUND The tear film lipid layer is formed from lipids secreted by meibomian glands of the eyelid. After initial analyses of these lipids we concluded that an understanding of the function of the various classes of lipids in a normal lipid layer could only be understood after detailed investigations of both polar and nonpolar lipids of the meibomian gland. METHODS Meibomian gland secretio...

New characteristics of O‡ ion velocity distribution functions in a background of atomic oxygen neutrals subjected to intense external electromagnetic forces are presented. The one dimensional (1-D) distribution function along the magnetic field displays a core-halo shape which can be accurately fitted by a two Maxwellian model. The Maxwellian shape of the 1-D distribution function around a pola...

Nonadiabatic effects in quantum dynamics are described using a mixed polar/coordinate space representation of the wave function. The polar part evolves on dynamically determined potential surfaces that have diabatic and adiabatic potentials as limiting cases of weak localized and strong extended diabatic couplings. The coordinate space part, generalized to a matrix form, describes transitions b...

The area of the polar cap a.s a function of local time and substorm phase was measured using images from the Polar Ultraviolet Imager (UVI) for different interplanetary magnetic field (IMF) orientations during three substorms in January 1997. We measured changes in the polar cap area and motion of the poleward and equatorward boundary of the auroral oval. It was found that the polar cap boundar...