Altered

Altered may refer to:

Altered (film)

Altered is a 2006 science fiction horror film directed by Eduardo Sánchez and written by Jamie Nash. It was Sánchez's first solo effort as director following his co-directing of The Blair Witch Project in 1999.

The plot is an inversion of the standard alien abduction formula, as four men abduct a lone alien, planning to wreak revenge on the invading species. In its early stages, the film was entitled Probed, and was intended as a comic homage to work of Sam Raimi and Troma Entertainment.

Plot synopsis

Altered is the story of four men who seek revenge on aliens that abducted them and murdered their friend many years ago. As is explained via dialogue throughout the film, fifteen years before the events shown in the film, a group of five fifteen-year-old friends living in a remote American town were captured and experimented on by aliens while on a hunting trip. Only four of the friends returned alive. The main character (Wyatt) has since distanced himself from his childhood friends and is shown to have decided to live with the past, albeit in apparent constant paranoia. Two of the remaining three characters however have been obsessed by revenge and have persuaded the remaining, somewhat leadable, character that this is the correct course of action to take. The story opens with the tracking and subsequent capture of a lone alien - the consequences of which Wyatt and the three friends soon become deeply involved in.

Alternation (geometry)

In geometry, an alternation or partial truncation, is an operation on a polygon, polyhedron, tiling, or higher dimensional polytope that removes alternate vertices.

Coxeter labels an alternation by a prefixed by an h, standing for hemi or half. Because alternation reduce all polygon faces to half as many sides, it can only be applied for polytopes with all even-sided faces. An alternated square face becomes a digon, and being degenerate, is usually reduced to a single edge.

More generally any vertex-uniform polyhedron or tiling with a vertex configuration consisting of all even-numbered elements can be alternated. For example the alternation a vertex figure with 2a.2b.2c is a.3.b.3.c.3 where the three is the number of elements in this vertex figure. A special case is square faces whose order divide in half into degenerate digons. So for example, the cube 4.4.4 is alternated as 2.3.2.3.2.3 which is reduced to 3.3.3, being the tetrahedron, and all the 6 edges of the tetrahedra can also be seen as the degenerate faces of the original cube.

Percolation

In physics, chemistry and materials science, percolation (from Lat. percōlāre, to filter or trickle through) refers to the movement and filtering of fluids through porous materials.

Background

During the last five decades, percolation theory, an extensive mathematical model of percolation, has brought new understanding and techniques to a broad range of topics in physics, materials science, complex networks, epidemiology, and other fields . For example, in geology, percolation refers to filtration of water through soil and permeable rocks. The water flows to groundwater storage (aquifer).

Percolation typically exhibits universality. Statistical physics concepts such as scaling theory, renormalization, phase transition, critical phenomena and fractals are used to characterize percolation properties. Combinatorics is commonly employed to study percolation thresholds.

Due to the complexity involved in obtaining exact results from analytical models of percolation, computer simulations are typically used. The current fastest algorithm for percolation was published in 2000 by Mark Newman and Robert Ziff.