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A novel approach for the practical realization of feeding lines in connected array slots is presented. The proposed feed concept based on a parallel-plate waveguide (PPW) structure and allows simplifying unit cell design. When compared to typical integrated coaxial feed, PPW-based can reduce cost complexity array, by resulting lower number metal layers allowing large diameter vias. Two examples...

Let T be a unit equilateral triangle, and T1, . . . , Tn be n equilateral triangles that cover T and satisfy the following two conditions: (i) Ti has side length ti (0 < ti < 1); (ii) Ti is placed with each side parallel to a side of T . We prove a conjecture of Zhang and Fan asserting that any covering that meets the above two conditions (i) and (ii) satisfies ∑n i=1 ti ≥ 2. We also show that ...

This paper gives a proof that the universal cover of a closed 3-manifolds built from three π1-injective handlebodies is homeomorphic to R .

We prove that the set of homotopy classes of the paths in a topological ring is a ring object (called ring groupoid). Using this concept we show that the ring structure of a topological ring lifts to a simply connected covering space.

The purpose of this note is to use covering space theory to construct new examples of buildings. On the level of Coxeter systems, this contsruction was described previously in Davis [4]. It goes as follows. Start with a Coxeter system (W ′, S). Change some m(s, t)’s in its Coxeter matrix from integers ≥ 2 to the symbol ∞ . This defines a new Coxeter system (W, S). Suppose C′ is a building of ty...

This article contains a new argument which proves vanishing of the first cohomology for negative vector bundles over a complex projective variety if the rank of the bundle is smaller than the dimension of the base. Similar argument is applied to the construction of holomorphic functions on the universal covering of the complex projective variety .

This paper describes certain properties of the fundamental group of the shrinking wedge of circles. Covering space theory is an inadequate tool since the shrinking wedge of circles is not semi-locally simply connected. We conclude with the fact that the shrinking wedge of circles is not homotopy equivalent to the wedge product of a countable number of circles.

The luminous blue variable η Carinae is almost certainly a double star: a hot secondary in an eccentric orbit around a massive primary. Radio observations with the Australia Telescope Compact Array at a wavelength of 3 cm, covering the period from 1992 to 2002, suggest that at the time of last periastron, 1998.0, material was tidally lifted from the primary star into its equatorial disc.

This research-based essay presents survey results—collected from faculty in 104 PhDgranting management departments of AACSB-accredited business schools in the United States—regarding 11 different types of questionable research conduct, including data fabrication, data falsification, plagiarism, inappropriately accepting or assigning authorship credit, and publishing the same data or results in ...