amplificationgenetics

in acoustics and electronics, any change in a signal that alters the basic waveform or the relationship between various frequency components; it is usually a degradation of the signal. Straight amplification or attenuation without alteration of the waveform is not usually considered to be distortion. Amplitude distortion refers to unequal amplification or attenuation of the various frequency...

...major vocal attribute, depends primarily on the amplitude of vocal cord vibrations and thus on the pressure of the subglottic airstream. The greater the expiratory effort, the greater the vocal volume. Another component of vocal intensity is the radiating efficiency of the sound generator and its superimposed resonator. The larynx has been compared to the physical shape of a horn. This...

American electrical engineer who discovered and developed the negative-feedback principle, in which amplification output is fed back into the input, thus producing nearly distortionless and steady amplification. The principle has found widespread applications in electronics.

The earliest known attempt to amplify a sound wave was made by Athanasius Kircher, of “bell-in-vacuum” fame; Kircher designed a parabolic horn that could be used either as a hearing aid or as a voice amplifier. The amplification of body sounds became an important goal, and the first stethoscope was invented by a French physician, René Laënnec, in the early 19th...

Gene amplification is another type of chromosomal abnormality exhibited by some human tumours. It involves an increase in the number of copies of a proto-oncogene, an aberration that also can result in excessive production of the protein encoded by the proto-oncogene. Amplification of the N-MYC proto-oncogene is seen in about 40 percent of cases of neuroblastoma, a tumour of the...

...disrupting the delicate balance of the mechanisms of cell growth. Many leukemias and lymphomas are caused by translocations of proto-oncogenes. The third method of transformation involves an amplification in the number of copies of the proto-oncogene, which also can result in overproduction of the protein and its concomitant effects. Amplified proto-oncogenes have been found in tumours...

...to make recombinant DNA, which can then be amplified and manipulated, studied, or used to modify the genomes of other organisms by transgenesis. A fundamental step in recombinant DNA technology is amplification. This is carried out by inserting the recombinant DNA molecule into a bacterial cell, which replicates and produces many copies of the bacterial genome and the recombinant DNA...

...the desired level. In such cases the output of the first amplifier is fed into a second, whose output is fed to a third, and so on, until the output level is satisfactory. The result is cascade, or multistage amplification. Long-distance telephone, radio, television, electronic control and measuring instruments, radar, and countless other devices all depend on this basic process of...

...control and measuring instruments, radar, and countless other devices all depend on this basic process of amplification. The overall amplification of a multistage amplifier is the product of the gains of the individual stages.

...between various frequency components; it is usually a degradation of the signal. Straight amplification or attenuation without alteration of the waveform is not usually considered to be distortion. Amplitude distortion refers to unequal amplification or attenuation of the various frequency components of the signal, and phase distortion refers to changes in the phase relationships between...