Stokes posets and serpent nests

We study two different objects attached to an arbitrary quadrangulation of a regular polygon. The first one is a poset, closely related to the Stokes polytopes introduced by Baryshnikov. The second one is a set of some paths configurations inside the quadrangulation, satisfying some specific constraints. These objects provide a generalisation of the existing combinatorics of cluster algebras and nonnesting partitions of type A.Comment: 24 pages, 12 figure

Manifolds associated with (Z2)n(Z_2)^n-colored regular graphs

In this article we describe a canonical way to expand a certain kind of $(\mathbb Z_2)^{n+1}$-colored regular graphs into closed $n$-manifolds by adding cells determined by the edge-colorings inductively. We show that every closed combinatorial $n$-manifold can be obtained in this way. When $n\leq 3$, we give simple equivalent conditions for a colored graph to admit an expansion. In addition, we show that if a $(\mathbb Z_2)^{n+1}$-colored regular graph admits an $n$-skeletal expansion, then it is realizable as the moment graph of an $(n+1)$-dimensional closed $(\mathbb Z_2)^{n+1}$-manifold.Comment: 20 pages with 9 figures, in AMS-LaTex, v4 added a new section on reconstructing a space with a $(Z_2)^n$-action for which its moment graph is a given colored grap

Breeding biology of pond heron in Kerala, South India

Regular intensive investigations to locate nesting colonies were carried out early monsoon of 1999 up to 2002. For detailed study a few breeding colonies were selected. The nesting trees, nest characteristics, eggs characteristics, incubation, hatching and hatchlings were investigated.

Altogether 17 plant species were used for nesting. Nest materials were collected from 24 plant species for building nest. The mean maximum size of the nest material used was 29.05 cm and the mean minimum size was 13.46 cm. The clutch size varied from 2-5 and clutches of three were very common. The maximum and minimum length and breadth of eggs were 48.0 x 32.0 and 33.3 x 24.1 respectively. The weight of eggs varied between 17.8 and 11.2 gm. Both sexes take part in incubation that extended for 18-24 days. Hatching success reached 82%. Their food consisted mainly of fishes and both parents took part in feeding the nestlings

An internal characterisation of radiality

In this paper, we will investigate how radiality occurs in topological spaces by considering neighbourhood bases generated by nests. We will define a new subclass of radial spaces, called the independently-based spaces, that contains LOTS, GO-spaces and spaces with well-ordered neighbourhood bases. We show that first-countable spaces are precisely the independently-based, strongly Fr\'echet spaces and we give an example of a Fr\'echet-Urysohn space that is neither independently-based nor strongly Fr\'echet.Comment: 11 pages. Changelog: cleaned up LaTeX source and fixed 'folgenbestimmt' typo (thanks to Thilo Weinart for spotting this!

Notes on the Nests of \u3ci\u3eAugochloropsis metallica fulgida\u3c/i\u3e and \u3ci\u3eMegachile mucida\u3c/i\u3e in Central Michigan (Hymenoptera: Halictidae, Megachilidae)

Notes on the nesting biology of two ground-nesting species are provided from Central Michigan. A single nest of Augochloropsis metallica fulgida was excavated on 12 July 2014 in Shiawassee County. There were two female nest inhabitants. Examination of mandibular wear, wing wear and ovarial development suggests one female was acting as a worker caste. Also, a nesting aggregation of Megachile mucida was observed in Ingham County. Information on nest architecture and cell construction is based on excavations of several nests during 7–15 June 2014. Megachile mucida is recorded as a new host species for the cleptoparasite Coelioxys sodalis. This is the first record of M. mucida in Michigan, additional collection records of this species in Michigan are also reported

Spreads Admitting Regular Elliptic Covers

We say that a spread S of PG(3, q) admits a regular elliptic cover if and only if S contains q−1 pairwise disjoint reguli (necessarily covering all but two fixed lines of S). Clearly, any André spread satisfies this condition. In this paper, we construct an infinite family of non-Andrd spreads admitting regular elliptic covers by replacing (q + 1)-nests of reguli in a regular spread. These are the only known non-André spreads to admit such a cover. The collineation groups of these spreads are also discussed in detail