We discuss a finite rectangular well as a perturbation for the infinite one with a depth λ of the former as a perturbation parameter. In particular we consider a behaviour of energy levels in the well as functions of complex λ. It is found that all the levels of the same parity are defined on infinitely sheeted Riemann surfaces which topological structures are described in details. These struct...

The theory of supercharacters, recently developed by DiaconisIsaacs and André, can be used to derive the fundamental algebraic properties of Ramanujan sums. This machinery frequently yields one-line proofs of difficult identities and provides many novel formulas. In addition to exhibiting a new application of supercharacter theory, this article also serves as a blueprint for future work since s...

In 1959, Oliver Selfridge proposed a model of letter perception, the Pandemonium model, in which the central hypothesis was that letters are identified via their component features. Although a consensus developed around this general approach over the years, key evidence in its favor remained lacking. Recent research has started to provide important evidence in favor of feature-based letter perc...

Abstract Spatiotemporal variation in fish assemblage structure was conducted from January to December 2015 in order to know the impacts of sanctuary on ichthyo-faunal diversity with its indices and major hydrological factors from six sampling stations of Karatoya fish sanctuary sectioned in the river Karatoya. A total of 69 fish species was obtained from this sanctuary including 21 threatened ...