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PRISM is a code name for a program under which the United States National Security Agency (NSA) collects internet communications from various U.S. internet companies. [1] [2] [3] The program is also known by the SIGAD US-984XN. [4] [5] PRISM collects stored internet communications based on demands made to internet companies such as Google LLC ...
Enamel prism. An enamel prism, or enamel rod, is the basic unit of tooth enamel. Measuring 3-6 μm in diameter in primates, [1] enamel prism are tightly packed hydroxyapatite crystals structures. The hydroxyapatite crystals are hexagonal in shape, providing rigidity to the prism and strengthening the enamel.
Lamps as seen through a prism. In optics, a dispersive prism is an optical prism that is used to disperse light, that is, to separate light into its spectral components (the colors of the rainbow ). Different wavelengths (colors) of light will be deflected by the prism at different angles. [1] This is a result of the prism material's index of ...
Prism is the fourth studio album by American singer Katy Perry. It was released by Capitol Records on October 18, 2013. While the album was initially planned to be "darker" than her previous material, Prism ultimately became a prominently dance-inspired record. Perry worked with several past collaborators, while enlisting new producers and ...
Porro prisms are most often used in pairs, forming a double Porro prism. A second prism rotated 90° with respect to the first, is placed such that light will traverse both prisms. The net effect of the prism system is a beam parallel to but displaced from its original direction, with the image rotated 180°. A double Porro system provides four ...
Incomitant strabismus cannot be fully corrected by prism glasses, because the eyes would require different degrees of prismatic correction dependent on the direction of the gaze. Incomitant strabismus of the eso- or exo-type are classified as "alphabet patterns": they are denoted as A- or V- or more rarely λ -, Y- or X-pattern depending on the ...
PRISM is a probabilistic model checker, a formal verification software tool for the modelling and analysis of systems that exhibit probabilistic behaviour. One source of such systems is the use of randomization , for example in communication protocols like Bluetooth and FireWire , or in security protocols such as Crowds and Onion routing .
In geometry, the hexagonal prism is a prism with hexagonal base. Prisms are polyhedrons; this polyhedron has 8 faces, 18 edges, and 12 vertices. [1] Since it has 8 faces, it is an octahedron. However, the term octahedron is primarily used to refer to the regular octahedron, which has eight triangular faces. Because of the ambiguity of the term ...