Clusters averaging 75 to 80 individuals live together in complex systems of burrows in arid African deserts.

Clusters of memes, or memeplexes ( also known as meme complexes or as memecomplexes ), such as cultural or political doctrines and systems, may also play a part in the acceptance of new memes.

* Clusters of consonants may be simplified, producing silent letters e. g. silent ⟨ th ⟩ in asthma, silent ⟨ t ⟩ in Christmas.

Clusters are made of two or more consonant sounds, while a digraph is a group of two consonant letters standing for a single sound.

Clusters of trigger points are not uncommon in some of the larger muscles, such as the gluteus group ( gluteus maximus, gluteus medius, and gluteus minimus ).

High availability clusters ( HAC ) improve application availability by failing them over or switching them over in a group of systems — as opposed to High Performance Clusters, which improve application performance by running them on multiple systems simultaneously.

Clusters consist of geographical areas.

The Jewel Box Clusters is a Shapley class g and Trumpler class I 3 r cluster ; it is a very rich, centrally-concentrated cluster detached from the surrounding star field.

Clusters correspond generally to the concept of an " object " in an OO language, and have roughly the same syntax.

Clusters are not a syntactic language construct, but rather a standard organizational convention.

Clusters of galaxies are often dominated by a single giant elliptical galaxy, known as the brightest cluster galaxy, which, over time, tidally destroys its satellite galaxies and adds their mass to its own.

Clusters are then formed relatively recently between 10 billion years ago and now.

Clusters are larger than groups, although there is no sharp dividing line between the two.

Clusters are quite prominent in X-ray surveys and along with AGN are the brightest X-ray emitting extragalactic objects.

* Gravitational lensing: Clusters of galaxies contain enough matter to distort the observed orientations of galaxies behind them.

Clusters of galaxies are the most recent and most massive objects to have arisen in the hierarchical structure formation of the universe and the study of clusters tells one about the way galaxies form and evolve.

Clusters have two important properties: their masses are large enough to retain any energetic gas ejected from member galaxies and the thermal energy of the gas within the cluster is observable within the X-Ray bandpass.

Their Catalogue of One Thousand New Nebulae and Clusters of Stars was published in 1786.

Clusters which have enough mass to be gravitationally bound once the surrounding nebula has evaporated can remain distinct for many tens of millions of years, but over time internal and external processes tend also to disperse them.

Clusters such as the Pleiades, Hyades and a few others within about 500 light years are close enough for this method to be viable, and results from the Hipparcos position-measuring satellite yielded accurate distances for several clusters.

The third announced the discovery of the fullerenes in " Reactivity of Large Carbon Clusters: Spheroidal Carbon Shells and Their Possible Relevance to the Formation and Morphology of Soot " in the Journal of Physical Chemistry v. 90 p 525 ( 1986 ).

Clusters are also a crucial step in determining the distance scale of the universe.

* Probing the Birth of Super Star Clusters: Implications for Massive Star Formation, Kelsey E. Johnson, 2005

He waited until 1802 ( in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars ; with Remarks on the Construction of the Heavens ) to announce the hypothesis that the two stars might be " binary sidereal systems " orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars ; with an Investigation of the Cause to which they are owing.

Herschel's discoveries were supplemented by those of Caroline Herschel ( 11 objects ) and his son John Herschel ( 1754 objects ) and published by him as General Catalogue of Nebulae and Clusters in 1864.

He published a catalogue of his astronomical observations in 1864, as the General Catalogue of Nebulae and Clusters, a compilation of his own work and that of his father's, expanding on the senior Hershel's Catalogue of Nebulae.

The New General Catalogue of Nebulae and Clusters of Stars ( abbreviated as NGC ) is a well-known catalogue of deep sky objects in astronomy compiled by John Louis Emil Dreyer in 1888, as a new version of John Herschel's Catalogue of Nebulae and Clusters of Stars.

Dreyer had already published a supplement to Herschel's General Catalogue of Nebulae and Clusters ( GC ), containing about 1, 000 new objects.

Detector and power rectifiers could not amplify a signal.

These adapters activate other intracellular molecules such as IRAK1, IRAK4, TBK1, and IKKi that amplify the signal, eventually leading to the induction or suppression of genes that cause certain responses.

The following essential elements are common to all superhet circuits: a receiving antenna, a tuned stage which may optionally contain amplification ( RF amplifier ), a variable frequency local oscillator, a frequency mixer, a band pass filter and intermediate frequency ( IF ) amplifer, and a demodulator plus additional circuitry to amplify or process the original audio signal ( or other transmitted information ).

Because the controlled ( output ) power can be higher than the controlling ( input ) power, a transistor can amplify a signal.

There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers.

Doped fiber amplifiers ( DFAs ) are optical amplifiers that use a doped optical fiber as a gain medium to amplify an optical signal.

If that amplifier is used to amplify a source having a noise temperature of about room temperature ( 290 K ), as many sources do, then the insertion of that amplifier would reduce the SNR of a signal by 6 dB.

In contrast, optical amplifiers, which amplify the light beam directly, are often used in transcontinental and submarine communications cables, because the signal loss over such distances would be unacceptable without them.

Some transmission systems contain multipliers, which amplify a signal prior to re-transmission, or regenerators, which attempt to reconstruct and re-shape the coded message before re-transmission.

One amplifier, the professional audio model DC300 made by Crown International beginning in the 1960s, did not have high-pass filtering at all, and could be used to amplify the DC signal of a common 9-volt battery at the input to supply 18 volts DC in an emergency for mixing console power.

This method can be used to amplify the signal.

EDFAs can amplify any optical signal in their operating range, regardless of the modulated bit rate.

In terms of multi-wavelength signals, so long as the EDFA has enough pump energy available to it, it can amplify as many optical signals as can be multiplexed into its amplification band ( though signal densities are limited by choice of modulation format ).

A bandpass amplifier would amplify the signal, so it could be detected.

A typical example of linear equipment is a high fidelity audio amplifier, which must amplify a signal without changing its waveform.

Optical amplifiers are used to amplify an optical signal.

In addition, a special amplifier is required to amplify the signal to deflect the membrane, which often requires electrical potentials in the range of 100 to 1000 volts.

This was the first use of a vacuum tube to amplify a signal, preceding even Lee de Forest's claim.

They are distinct from ordinary radios because they are passive receivers, while other radios use a separate source of electric power such as a battery or the mains power to amplify the weak radio signal from the antenna so it is louder.

A device exhibiting negative resistance can be used to amplify a signal and this is an especially useful technique at microwave frequencies.

Amplifiers are limited in the electrical energy they can amplify, while loudspeakers are limited in the electrical energy they can convert to sound energy without distorting the audio signal or damaging themselves.

The integrated circuit contains a receiver which uses the battery's power to amplify the signal from the reader unit so it is stronger, so it can detect the reader at a greater distance away.

When playing analog cassettes, portable players would simply amplify the signal from two of the nine heads of the " other side ": analog cassette recorders used the " bottom half " of the tape, while digital recordings used the " top half ".

A guitar amplifier ( or guitar amp ) is an electronic amplifier designed to amplify the electrical signal of an electric or acoustic guitar so that it will produce sound through a loudspeaker.