Rectangular function

The rectangular function (also known as the rectangle function, rect function, Pi function, gate function, unit pulse, or the normalized boxcar function) is defined as:

Alternative definitions of the function define to be 0, 1, or undefined.

Relation to the boxcar function

The rectangular function is a special case of the more general boxcar function:

Where u is the Heaviside function; the function is centered at X and has duration Y, from X-Y/2 to X+Y/2.

Another example is this: rect((t - (T/2)) / T ) goes from 0 to T, so in terms of Heaviside function u(t) - u((t-T) / T )

Fourier transform of the rectangular function

The unitary Fourier transforms of the rectangular function are

using ordinary frequency f, and

using angular frequency ω, where is the unnormalized form of the sinc function.

Note that as long as the definition of the pulse function is only motivated by the time-domain experience of it, there is no reason to believe that the oscillatory interpretation (i.e. the Fourier transform function) should be intuitive, or directly understood by humans. However, some aspects of the theoretical result may be understood intuitively, finiteness in time domain corresponds to an infinite frequency response. (Vice versa, a finite fourier transform will correspond to infinite time domain response.)

Parasitism

In biology/ecology, parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite (in biological usage) referred primarily to organisms visible to the naked eye, or macroparasites (such as helminths). Parasite can include microparasites, which are typically smaller, such as protozoa,viruses, and bacteria. Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms.

Unlike predators, parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period. Both are special cases of consumer-resource interactions. Parasites show a high degree of specialization, and reproduce at a faster rate than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and tapeworms, flukes, the Plasmodium species, and fleas. Parasitism differs from the parasitoid relationship in that parasitoids generally kill their hosts.

Parasite (Heroes)

"Parasite" is the eighteenth episode of the first season of the NBC science fiction drama series Heroes. It was unique in that, in some markets, the introductory phrase "Previously on Heroes" was written in Japanese and spoken by Hiro, unlike the English that had always preceded it. It was originally announced as "Like Any Parasite" until NBC shortened its name to "Parasite" on February 24, 2007. Like the previous episode, this episode debuted on Global in most Canadian markets a day ahead of NBC. This was the last episode to be aired until April 2007, when the series picked up once again to finish the season.

Plot

After Simone Deveaux dies, Isaac Mendez blames Peter Petrelli for her death and tries to shoot Peter, but he turns invisible and flies out the window. Distraught, Peter goes to Nathan for help. Nathan says he will leave an anonymous phone call to the police, directing them to Isaac's home. He advises Peter to get help from Mohinder, but Peter disappears again.

Parasite (Grant novel)

Parasite is a science fiction novel written by Mira Grant (the pseudonym of American author Seanan McGuire). It was released on October 29, 2013 by Orbit Books and is the first volume of the Parasitology trilogy . The other two books in the series are Symbiont (November 25, 2014) and Chimera (November 24, 2015).

References

External links