Abstract: A Luneburg antenna device includes a dielectric lens and an array antenna. The dielectric lens is a laminate of a plurality of disc members having distribution of permittivity varying with respect to its radial direction. Each of the disc members includes a planar section in which a thickness dimension of a radially outer area is smaller than a thickness dimension of a radially inner area and a fin section which extends in a radial manner from a central portion of the planar section toward a radially outer side and in which a radially inner area and a radially outer area have the same thickness dimension.

Abstract: A Luneburg antenna device includes a dielectric lens and an array antenna. The dielectric lens is a laminate of a plurality of disc members having distribution of permittivity varying with respect to its radial direction. Each of the disc members includes a planar section in which a thickness dimension of a radially outer area is smaller than a thickness dimension of a radially inner area and a fin section which extends in a radial manner from a central portion of the planar section toward a radially outer side and in which a radially inner area and a radially outer area have the same thickness dimension.

Abstract: A culture medium is provided that includes a reducing chromogenic reagent that does not give a coloration with Enterococcus faecium. There is also provided a method for differentiating Enterococcus faecium from Enterococcus faecalis in a sample, the method including a step of inoculating the above culture medium with the sample; and a step of differentiating between the two bacterial strains by observing the colony color during culture or after culturing.

Abstract: An X-ray conversion screen having reduced afterglow without any appreciable loss in the brightness under X-ray excitation comprises a substrate and at least one fluorescent layer applied thereto, the fluorescent layer containing a fluorescent substance which comprises terbium-activated lanthanum or gadolinium oxyhalide having yttrium or lutetium and, as desired, ytterbium added thereto as impurities.