RESUMO
Large random bit-strings known as 'keys' are used to encode and decode sensitive data, and the secure distribution of these keys is essential to secure communications across the globe. Absolutely secure key exchange between two sites has now been demonstrated over fibre and free-space optical links. Here we describe the secure exchange of keys over a free-space path of 23.4 kilometres between two mountains. This marks a step towards accomplishing key exchange with a near-Earth orbiting satellite and hence a global key-distribution system.
RESUMO
The amyloidoses are a heterogeneous group of diseases, which are characterized by the local or systemic deposition of amyloid. At the root of these diseases are changes in protein conformation where normal innocuous proteins transform into insoluble amyloid fibrils and deposit in tissues. The amyloid fibrils of Alzheimer's disease are composed of the Abeta peptide and deposit in the form of senile plaques. Neurodegeneration surrounds the amyloid deposits, indicating that neurotoxic substances are produced during the deposition process. Whether the neurotoxic species is the amyloid fibril or a fibril precursor is a current area of active research. This review focuses on advancements made in elucidating the molecular structures of the Abeta amyloid fibril and alternate aggregation products of the Abeta peptide formed during fibrillogenesis.
