Fractal analysis of polar bear hairs

The Stream Cipher Polar Bear

We propose a new stream cipher called “Polar Bear”. It combines constructions used successfully in other situations. The key initialization uses Rijndael, the steady state uses a dynamic table as in RC4 and we guarantee a long period through the use of a linear feedback shiftregister. The efficiency for short messages is better than that of RC4 while for long messages Polar Bear is about a fact...

The Polar Bear — Ursus maritimus

Climate change threatens polar bear populations: a stochastic demographic analysis.

The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with fo...

Is polar bear hair fiber optic?

New direct measurement of high optical attenuation rates in polar bear hairs--2-8 dB/mm in the visible--and reanalysis of the data of Tributsch et al. [Sol. Energy Mater. 21, 219 (1990)] seem to rule out the UV waveguiding proposed by Grojean et al. [Appl. Opt. 19, 339 (1980)]. The case against fiber-optic polar bear hairs is summarized, and four conditions are given that any variation of the m...

Biomechanical Consequences of Rapid Evolution in the Polar Bear Lineage

The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we ...