Abstract: Quorum-based access control management may be implemented. Quorum controls may be created for determining whether to perform or deny access control operations to perform privileged tasks. When an access control operation is received, approval of the operation may be requested from members for the quorum control. If a policy for the quorum control is satisfied by approval responses, then approval to perform the access control operation may be provided.

Abstract: An antenna element includes a patch antenna and a microstrip line separated by an electrochromic material to tune the element. A reflectarray of a plurality of antenna elements is formed on a substrate. The dielectric permitivities of the electrochromic material may be controlled both during manufacture and during operation of the antenna to provide a phase shift to the antenna elements and beamform a signal radiated by the antenna. A bias line may be used to change a shape, direction or circular polarity of a beam radiating from the antenna.

Abstract: An antenna element includes a patch antenna and a microstrip line separated by an electrochromic material to tune the element. A reflectarray of a plurality of antenna elements is formed on a substrate. The dielectric permitivities of the electrochromic material may be controlled both during manufacture and during operation of the antenna to provide a phase shift to the antenna elements and beamform a signal radiated by the antenna. A bias line may be used to change a shape, direction or circular polarity of a beam radiating from the antenna.

Abstract: A freestanding frequency selective surface (FSS) is provided which comprises at least one shorted resonance aperture element (12). The shorted resonance aperture element provides a sensitivity to polarization. The shorted resonance aperture element may comprise at least one short, which may enable the FSS to be freestanding. The invention further provides an FSS device comprising at least one array of the freestanding frequency selective surfaces, and a method of forming the freestanding frequency selective surfaces.

Abstract: A freestanding frequency selective surface (FSS) is provided which comprises at least one shorted resonance aperture element (12). The shorted resonance aperture element provides a sensitivity to polarisation. The shorted resonance aperture element may comprise at least one short, which may enable the FSS to be freestanding. The invention further provides an FSS device comprising at least one array of the freestanding frequency selective surfaces, and a method of forming the freestanding frequency selective surfaces.

Abstract: A frequency selective surface devise is described. The device separates or combines two channels by using two or three spaced layers of resonant elements which may be loops or tripoles and which are coupled and which have interactive effects between layers such that the relatively broad transmission and reflection bands characteristic of resonant elements are modified by reinforcement of multiple reflection between the layers in the manner of a Fabry-Perot etalon effect in order to increase the sharpness of the transition of the transmission and reflection bands and thereby to permit combination or separation of closely spaced channels.

Abstract: The invention relates to certain naphthoquinone derivatives, some of which are novel, of the general formula I ##STR1## in which R represents a hydrogen atom or a hydroxyl or an ethanoyloxy group; methods for their preparation; compositions containing such compounds and their use as pesticides, such as fungicides and, especially, insecticides and acaricides. Compounds of formula I may be derived from plants of the genus Calceolaria and the invention therefore also relates to extracts of a Calceolaria species and their use as pesticides.

Abstract: A process for the preparation of a monoalkyl ether having the formula ##STR1## wherein R is an alkyl radical having 1 to 18 carbon atoms or C.sub.2 H.sub.5 --O--CH.sub.2 CH.sub.2 -- and R.sup.1 is hydrogen or an alkyl radical having 1 to 4 carbon atoms, which comprises reacting a compound having the formula R--OH with a mixture of a compound having the formula ##STR2## and a compound having the formula ##STR3## in the presence of an acid dehydration catalyst, wherein the weight ratio of II:III is from 5:1 to 20:1.