A Different Polar Bear Book

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

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...

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...

Crescentic Glomerulonephritis in a Polar Bear (Ursus maritimus)

Spontaneous crescentic glomerulonephritis (CrGN) in animals has only been reported in dog and sheep. We report the pathological features of CrGN in a 17-year-old male polar bear that died due to renal failure. Histologically, the lesions were characterized by fibrocellular crescents, adhesion between Bowman's capsule and the glomerular capillary tuft and an increase in the mesangial matrix in g...