A community for providing user membership can be accessed via a portal. 5Ra5 and one of which has a surface at a temperature of at least, whereby occurrence of thread breakage or generation of fuzz may be prevented and synthetic fiber whereof the rate of operation can be increased and efficiency of manufacture is improved may be obtained. The low-pressure discharge lamp provides increased efficiency and reduced solarisation as compared to commercially available low-pressure discharge lamps. The first optical fiber and the second optical fiber are aligned with one another. It is contemplated that the bi-quad filter stage may comprise a series of bi-quad filters, wherein the impulse response filter stage is cascaded into at least one bi-quad filter of the series of bi-quad filters. Methods are also disclosed for designing the hydrofoil so that it has a natural resonant frequency that is sufficiently close the frequency of the reciprocating strokes used to attain propulsion in an amount sufficient to create harmonic wave addition that creates an amplified oscillation in the free end of the reciprocating hydrofoil.