RESUMEN

DNA libraries often contain very large numbers of clones (from 1000 up to 700,000). Since at present it is impossible to analyze all of these clones, usually statistical samples comprising less than 100 clones are tested. The quality of the library is then assessed by linear extrapolation. Occasionally, full coverage of chromosomal regions by DNA probes is inferred from this. However, this may not be accurate since linear extrapolation is misleading and the statistical samples are generally too small to characterize the libraries. A quantitative model of the distribution of the frequencies of the clones in a library is mandatory for any useful assessment of the quality of the library. Otherwise, it is very difficult to draw useful conclusions from moderately sized samples. Examples from everyday life and formulas are given to determine the quality of a library and useful sample sizes.

Asunto(s)

Biblioteca de Genes , Muestreo , Paseo de Cromosoma , Clonación Molecular , Sondas de ADN , Matemática , Hibridación de Ácido Nucleico

RESUMEN

The sensitivity limit for one-lane DNA sequencing based on laser-induced fluorescence is derived by statistical means. A closed-form expression for the sequencing error probability as a function of the signal strength and of the differences in the fluorescence properties of the labels is given. Fluctuations of the signal caused by photodestruction of the molecules cannot be neglected. The expected sequencing error probability is expressed in terms of the number of molecules and the physical parameters of the measurement. This equation can be used in many ways to design and optimize sequencing experiments.

RESUMEN

Several examples of laser in situ monitoring of combustion processes are presented. Using a frequency modulated (13)CO(2) waveguide laser, in situ concentrations of NH(3) down to 1 ppm were measured at temperatures up to 600 degrees C in waste incinerators and power or chemical plants. Following ignition of CH(3)OH-O(2) mixtures by a TEA CO(2) laser, gas temperature profiles were measured using rapid scanning tunable diode laser spectroscopy of CO molecules. In laminar CH(4)-air counterflow diffusion flames at atmospheric pressure absolute concentrations, temperatures, and collisional lifetimes of OH radicals were determined by 2-D and picosecond LIF and absorption spectroscopy. Two-dimensional LIF and Mie scattering were used to observe fuel injection and combustion in a diesel engine.