Integer Quantum Hall Effect in Graphene

We study the quantum Hall effect in a monolayer graphene by using an approach based on thermodynamical properties. This can be done by considering a system of Dirac particles in an electromagnetic field and taking into account of the edges effect as a pseudo-potential varying continuously along the $x$ direction. At low temperature and in the weak electric field limit, we explicitly determine the thermodynamical potential. With this, we derive the particle numbers in terms of the quantized flux and therefore the Hall conductivity immediately follows.Comment: 4 page

Bureaucracy and Corruption Taxation Proof

Using the Principal-Agent-Supervisor paradigm, we examine in this paper how a tax collection agency changes optimal schemes in order to lessen the occurrence of bribery between the tax collector and the taxpayer. The Principal, who maximizes the expected net fiscal revenue, reacts by decreasing tax rates when the supervisor is likely to engage in corrupt transaction with taxpayer. The combat against collusion may explain the greater reliance on indirect taxes than on direct taxes both in developed and developing countriesPrincipal Agent Supervisor;Bureaucracy ;Collusion; Tax evasion

Family Capitalism Corporate Governance Theory

Family firms, which are prevalent around the world both for small organizations and large corporations, are usually more performant than other types of firms. This paper draws on altruism and on the theory of incentives contracting to explain why family firms perform better. Assuming that altruism only exists in family firms, we show that the strength of family ties has an impact on the optimal contract only under asymmetric information. Then, we extend the analysis to the principal-agent supervisor setting and prove that the recruitment of family members may be seen as a device against collusion within a three-tier hierarchy.Family Capitalism; Altruism; Family Ties ;Asymmetric Information;Supervisor Agent Principal; Collusion

Hall Effect in Noncommutative Coordinates

We consider electrons in uniform external magnetic and electric fields which move on a plane whose coordinates are noncommuting. Spectrum and eigenfunctions of the related Hamiltonian are obtained. We derive the electric current whose expectation value gives the Hall effect in terms of an effective magnetic field. We present a receipt to find the action which can be utilized in path integrals for noncommuting coordinates. In terms of this action we calculate the related Aharonov--Bohm phase and show that it also yields the same effective magnetic field. When magnetic field is strong enough this phase becomes independent of magnetic field. Measurement of it may give some hints on spatial noncommutativity. The noncommutativity parameter \theta can be tuned such that electrons moving in noncommutative coordinates are interpreted as either leading to the fractional quantum Hall effect or composite fermions in the usual coordinates.Comment: 13 pages. Some references adde

FFZ realization of the deformed super Virasoro algebra - Chaichian-Presnajder type

The q-deformed super Virasoro algebra proposed by Chaichian and Presnajder is examined. Presented is the realizations by the FFZ algebra (the magnetic translation algebra) defined on a two-dimensional lattice with a supersymmetric Hamiltonian.Comment: Latex 9 pages, a couple of short comments are adde

Culture Values Entrepreneurship and Growth

We integrate a social norm which associates status to accumulation of capital and consumption into a simple model of endogenous growth. We show that societies which place a greater weight of cultural values on stock of accumulated capital as opposed to consumption will experience fast growth. Our results are consistent with those obtained by Baumol (1990) in the context of entrepreneurship and by Fershtman and Weiss (1991).Entrepreneurship;Culture Values;Social Status;Growth