In the Lake Tanganyika cichlid Lamprologus callipterus, males were >12 times heavier than females, the most extreme sexual size dimorphism in this direction among animals. L. callipterus males construct nests of empty snail shells in which the females breed. If the ancestors of L. callipterus were small cichlids, both sexes may have used shells for shelter. If the ancestors were larger, snail s...

We investigated the changes in plasma sex steroid hormones, testosterone (T), estradiol-17β (E2), 17,20β -dihydroxy-4-pregnen-3-one (17α20βP), 11-ketotestosterone (11KT) and cortisol levels from ribbed gunnel, Dictyosoma burgeri in associated with annual reproductive cycle. The gonadosomatic index (GSI) of females increased from November, peaked in February and decreased rapidly from March. The...

We present a theory for the coupled flow of ice, subglacial water and subglacial sediment, which is designed to represent the processes which occur at the bed of an ice sheet. The ice is assumed to flow as a Newtonian viscous fluid, the water can flow between the till and the ice as a thin film, which may thicken to form streams or cavities, and the till is assumed to be transported, either thr...

There are 509 expanding neutral hydrogen shells catalogued in the Small Magellanic Cloud (SMC), all apparently very young, with dynamical ages of a few Myr. To examine their relationship with young stellar objects we cross-correlated the shell catalogue with various catalogues of OB associations, super giants, Cepheids, WR stars, supernova remnants, and star clusters. The incidence of chance li...

The high efficiency of circular monocoque cylindrical shells in carrying axial loads is impaired by their extreme sensitivity to imperfections and there is an extensive body of literature that addresses this behavior. Instead of following this classical path, focused on circular cross-sections, this paper presents a novel approach that adopts optimal symmetry-breaking wavy cross-sections (wavy ...

Large crystalline molecular shells, such as some viruses and fullerenes, buckle spontaneously into icosahedra. Meanwhile multicomponent microscopic shells buckle into various polyhedra, as observed in many organelles. Although elastic theory explains one-component icosahedral faceting, the possibility of buckling into other polyhedra has not been explored. We show here that irregular and regula...

Elastic stability of ring and stringer-stiffened cylindrical shells under axial, internal and external pressures is studied using Ritz method. The stiffeners are rings, stringers and their different arrangements at the inner and outer surfaces of the shell. Critical buckling loads are obtained using Ritz method. It has been found that the cylindrical shells with outside rings are more stable th...

Abstract This research proposed the modular prefabricated permanent formwork system made of ultra-high-performance concrete (UHPC). Two kinds shapes were designed: flat and ribbed. The experimental investigation on axial compression performance composite columns that consist normal strength (NSC) core UHPC was demonstrated. Compared with formwork, ribbed exhibited better bonding NSC core. As ob...

Ribbed reinforcing steel bars (rebars) are used for the reinforcement of concrete structures. In service, they subjected to cyclic loading. Several studies addressing relationship between rib geometry, stresses at rebar surface induced by service loads and fatigue performance can be found in literature. However, rebar’s is also influenced residual originating from manufacturing process. this co...