An essential element for driver safety is represented by the Impact Attenuator (especially race cars). The effect of can be seen in behavior a dummy, tied with seat belt, frontal collision rigid wall. loads that act on dummy are determined and checked to see if they fall within values recommended existing standards. car considered structure fixed belt equipped an Attenuator. Two types having co...

β-lactamase, altered porins, or both are usually responsible for cefoxitin resistance in Escherichia coli. We examined the relative importance of each. We studied 18 strains of clinical isolates with reduced cefoxitin susceptibility and 10 initially-susceptible strains passaged through cefoxitin-gradient plates. Of 18 wild-resistant strains, 9 had identical promoter mutations (including creatio...

It has been proposed that uncharged tRNA molecules may act as positive regulatory factors to control the expression of a number of operons in Bacillus subtilis and related bacteria by interacting with leader sequences to cause antitermination. In this study we report the isolation and characterization of regulatory mutations that modify one of the tRNA molecules predicted to have such a regulat...

Expression of the tryptophan (trp) operon of Escherichia coli was shown to be regulated by attenuation in an in vitro DNA-dependent protein-synthesizing system. In extracts prepared from a temperature-sensitive tryptophanyl-tRNA synthetase mutant, plasmid-directed trpE enzyme synthesis was inhibited 2- to 3-fold by addition of purified wild type tryptophanyl-tRNA synthetase. When the extract us...

It is shown that a surface wave will be generated by a horizontal.slot situated above a corrugated or dielectric-coated guiding surface. A physical interpretation of the analysis is suggested which explains the mechanism of launching in terms of a resonance phenomenon allied to that which arises when a piston attenuator is terminated by a reactance equal and opposite to its own (reactive) chara...

We fabricate and measure a microfluidic variable optical attenuator, which consists of an optical waveguide integrated with a microfluidic channel. An opening is introduced in the upper cladding of the waveguide in order to facilitate the alignment and bonding of the microfluidic channel. By using fluids with different refractive indices, the optical output power is gradually attenuated. We obt...