Hybrid power amplifier

Currently, three basic high-frequency power amplifiers are in use the parallel connection of a bank of bipolar power transistors, the hybrid connection of parallel bipolar power transistors cascaded with metal oxide silicon field effect transistors (MOSFETs), and the bridge connection of MOSFETs. Each has unique properties and represents a stage in the evolution of ESUs. 

In situ polymerase chain reaction (PCR) is a very powerful tool, which enhances our ahility to detect minute quantities of a rare, single copy number, target nucleic acid sequences in freshly frozen or paraffin-embedded intact cells or tissue sections (1-10). In 1986, the introduction of PCR methods opened new horizons and revolutionized research in all areas of molecular biology (11,12). Dr. Hasse and his coworkers in 1990 used multiple primers and successfully amplified the target nucleic acid sequences in intact cells by combining a traditional in situ hybridization protocol with a powerful PCR technology (13). 

There are however difficulties in running multiplex PCR, and it is difficult to differentiate PCR products of approximately the same size in a multiplex PCR or PCR-RFLP gel. However DNA microarrays do not have these problems, and have been used to serotype pathogenic strains and proved to be rapid, reliable and sensitive. The approach involves the immobilization of numerous oligonucleotide DNA probes on a solid support to which fluorescence-labeled amplified target DNA is hybridized, and is a powerful tool for the detection of pathogens by virtue of high throughput, speed and sensitivity. 

Although this amplification technique is very sensitive and has tremendous application potential, it is not without problems. The powerful amplification procedure may yield false-positive results when samples are contaminated by nucleic acid left over from previously amplified DNA. Other problems include primer artifact formation and nonspecific hybridization of primers to DNA samples. Several modifications to the original PCR technology have been made over the years to improve the sensitivity and application potential for PCR, including the use of multiple sets of amplification primers, multiplex PCR, PCR amplification of RNA by converting targeted RNA with reverse transcriptase to complementary DNA templates (which are then suitable for DNA amplification by traditional PCR techniques), and real-time quantitative PCR. 

For optical applications, inorganic silicate-based oxide [2], non-oxide sulfide [3], and hybrid [4] and nanocomposite thin films [5] have been extensively studied, for passive or active optical components in integrated optical applications, including power splitters, Er " -dof>ed optical amplifiers for dense wavelength division multiplexer (DWDM) systems, and Au nanoparticle (NP)-doped optical sensors. However, sol-gel-derived materials may often differ from their melt-quenched analogues, even for the simple compoimd Si02- In these... 

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