An amplifier for a differential signal drain is able to amplify a signal over a frequency range and boost the signal within a specified frequency range. A sensor detects the presence of an object such as a human finger in the close vicinity or in contact with the monitor in order to stop the operation of the lights. In some embodiments, a competition is conducted for the design of web site content to be optimized. A latch engages the closure member to hold it in the closed position. In the method the aqueous gel of nanofibrillar cellulose is introduced into the volume of organic extraction agent in the form of one or several elongated elements which form a fiber-like or ribbon-like or film-like product after drying.