824 research outputs found
Theory of correlations in strongly interacting fluids of two-dimensional dipolar bosons
Ground-state properties of a two-dimensional fluid of bosons with repulsive
dipole-dipole interactions are studied by means of the Euler-Lagrange
hypernetted-chain approximation. We present a self-consistent semi-analytical
theory of the pair distribution function and ground-state energy of this
system. Our approach is based on the solution of a zero-energy scattering
Schr\"{o}dinger equation for the "pair amplitude" with an
effective potential from Jastrow-Feenberg correlations. We find excellent
agreement with quantum Monte Carlo results over a wide range of coupling
strength, nearly up to the critical coupling for the liquid-to-crystal quantum
phase transition. We also calculate the one-body density matrix and related
quantities, such as the momentum distribution function and the condensate
fraction.Comment: 8 pages, 8 figures, submitte
The investigation of limiting factors of earnings management for companies’ listed Tehran stock exchange
The current study was to examine the limiting factors of earnings management for companies’ listed Tehran stock exchange. The study was a kind of applied, descriptive- correlative research. All listed companies in Tehran stock exchange were selected as statistical population during 2009 to 2013. So, data was gathered by library method and collected by systematic eliminated sampling method. The results show that there is a significant inverse relationship between board size and earnings management in companies’ listed Tehran stock exchange. The result doesn’t show any significant relationship between dividend and earnings management in companies’ listed Tehran stock exchange.Keywords: real earnings management; accrual earnings management; discretionary accruals; non-discretionary accruals; intensive factor
Topological electric current from time-dependent elastic deformations in graphene
We show the possibility of inducing an edge charge current by applying
time-dependent strain in gapped graphene samples preserving time reversal
symmetry. We demonstrate that this edge current has the same origin as the
valley Hall response known to exist in the system.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.
Electron-electron interactions in decoupled graphene layers
Multi-layer graphene on the carbon face of silicon carbide is an intriguing
electronic system which typically consists of a stack of ten or more layers.
Rotational stacking faults in this system dramatically reduce inter-layer
coherence. In this article we report on the influence of inter-layer
interactions, which remain strong even when coherence is negligible, on the
Fermi liquid properties of charged graphene layers. We find that inter-layer
interactions increase the magnitudes of correlation energies and decrease
quasiparticle velocities, even when remote-layer carrier densities are small,
and that they lessen the influence of exchange and correlation on the
distribution of carriers across layers.Comment: 8 pages, 4 figures, submitte
Finite-temperature Screening and the Specific Heat of Doped Graphene Sheets
At low energies, electrons in doped graphene sheets are described by a
massless Dirac fermion Hamiltonian. In this work we present a semi-analytical
expression for the dynamical density-density linear-response function of
noninteracting massless Dirac fermions (the so-called "Lindhard" function) at
finite temperature. This result is crucial to describe finite-temperature
screening of interacting massless Dirac fermions within the Random Phase
Approximation. In particular, we use it to make quantitative predictions for
the specific heat and the compressibility of doped graphene sheets. We find
that, at low temperatures, the specific heat has the usual normal-Fermi-liquid
linear-in-temperature behavior, with a slope that is solely controlled by the
renormalized quasiparticle velocity.Comment: 9 pages, 5 figures, Submitted to J. Phys.
The impact of teamwork on an organization’s performance: a cooperative game’s approach
In this article we study the impact of teamwork on the organizations’ performance, considering a cooperative game’s framework. To promote the teamwork culture, performance indexes are considered individually and collectively, respectively, and by comparing the scores that every employee earns individually and collectively, their differences become obvious. In this approach, a cooperative games’ model is used in order to improve the organization’s performance. The proposed model, in addition to evaluating the organization and employee's activities, can implement all payments, including the overtime pay, reward, etc., fairly and along with increasing performance and satisfaction. The cooperative approach creates effective communications between employees and authorities and enhances their motivation for teamwork. Moreover, results can be used for decisions related to employees (such as promotion, transition, firing, and detachment), analysis of training requirements, employees’ development, and research and plan valuation. Our findings show that the collaborative coefficient is a key factor in increasing productivity and improving the efficiency of an organization in the long run. The collaborative coefficient is a new concept in teamwork that has rarely been considered in scientific research.info:eu-repo/semantics/publishedVersio
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