The concept of Pulaaku mirrored in fulfulde proverbs of the Gombe dialect

The paper gives a brief history of the Fulçe people who are found all over West and Central Africa. Since no study of a people is complete without mentioning their language, the paper also gives a very brief account of Fulfulde, the language of the Fulçe people. However, the central focus of the paper is the concept of pulaaku, that unique attribute of the Fulçe that serves as an unwritten code of conduct for all ‘true’ Fulçe. Pulaaku is Fulçe’s guiding principle in their dealings with their fellow Fulçe as well as with all other people. Rather than talk about pulaaku in isolation, however, the paper tries to mirror it through Fulfulde proverbs. Coded or loaded messages called wise-sayings or proverbs are widely used in all languages. Fulfulde is particularly rich in this, which is why the paper explores this reservoir of knowledge in trying to portray the rich culture of the Fulçe people. The corpus of proverbs from which the selected proverbs come, was compiled in and around Gombe with the help of Mallam Bappayo Bappa Yerima Djibril. Since the Fulçe are easily the most dispersed people in Africa, no single study can do real justice to all of them. This is why this study narrows its scope to cover just the Fulçe of Gombe area of the northeastern of Nigeria

The Phillips Curve Under State-Dependent Pricing

This paper is related to a large recent literature studying the Phillips curve in sticky-price equilibrium models. It differs in allowing for the degree of price stickiness to be determined endogenously. A closed-form solution for short-term inflation is derived from the dynamic stochastic general equilibrium (DSGE) model with state-dependent pricing originally developed by Dotsey, King and Wolman. This generalised Phillips curve encompasses the New Keynesian Phillips curve (NKPC) based on Calvo-type price-setting as a special case. It describes current inflation as a function of lagged inflation, expected future inflation, and current and expected future real marginal costs. The paper demonstrates that inflation dynamics generated by the model for a broad class of time and state-dependent price-setting behaviours are well approximated by the popular hybrid NKPC (with one lag of inflation) in a low-inflation environment. This provides an explanation of why the hybrid NKPC performs well in describing inflation dynamics across industrial countries. It implies, however, that the reduced-form coefficients of the hybrid NKPC may not have a structural interpretationState-dependent pricing, inflation dynamics, Phillips curve.

On an explicit finite difference method for fractional diffusion equations

A numerical method to solve the fractional diffusion equation, which could also be easily extended to many other fractional dynamics equations, is considered. These fractional equations have been proposed in order to describe anomalous transport characterized by non-Markovian kinetics and the breakdown of Fick's law. In this paper we combine the forward time centered space (FTCS) method, well known for the numerical integration of ordinary diffusion equations, with the Grunwald-Letnikov definition of the fractional derivative operator to obtain an explicit fractional FTCS scheme for solving the fractional diffusion equation. The resulting method is amenable to a stability analysis a la von Neumann. We show that the analytical stability bounds are in excellent agreement with numerical tests. Comparison between exact analytical solutions and numerical predictions are made.Comment: 22 pages, 6 figure

Vertical distribution and composition of phytoplankton under the influence of an upper mixed layer

The vertical distribution of phytoplankton is of fundamental importance for the dynamics and structure of aquatic communities. Here, using an advection-reaction-diffusion model, we investigate the distribution and competition of phytoplankton species in a water column, in which inverse resource gradients of light and a nutrient can limit growth of the biomass. This problem poses a challenge for ecologists, as the location of a production layer is not fixed, but rather depends on many internal parameters and environmental factors. In particular, we study the influence of an upper mixed layer (UML) in this system and show that it leads to a variety of dynamic effects: (i) Our model predicts alternative density profiles with a maximum of biomass either within or below the UML, thereby the system may be bistable or the relaxation from an unstable state may require a long-lasting transition. (ii) Reduced mixing in the deep layer can induce oscillations of the biomass; we show that a UML can sustain these oscillations even if the diffusivity is less than the critical mixing for a sinking phytoplankton population. (iii) A UML can strongly modify the outcome of competition between different phytoplankton species, yielding bistability both in the spatial distribution and in the species composition. (iv) A light limited species can obtain a competitive advantage if the diffusivity in the deep layers is reduced below a critical value. This yields a subtle competitive exclusion effect, where the oscillatory states in the deep layers are displaced by steady solutions in the UML. Finally, we present a novel graphical approach for deducing the competition outcome and for the analysis of the role of a UML in aquatic systems.Comment: 20 pages, 8 figure

User interface development and software environments : the Chiron-1 system

User interface development systems for software environments have to cope with the broad, extensible and dynamic character of such environments, must support internal and external integration, and should enable various software development strategies. The Chiron-1 system adapts and extends key ideas from current research in user interface development systems to address the particular demands of software environments. Important Chiron-1 concepts are: separation of concerns, dynamism, and open architecture. We discuss the requirements on such user interface development systems, present the Chiron-1 architecture and a scenario of its usage, detail the concepts it embodies, and report on its design and prototype implementation

Electrostatic interactions mediated by polarizable counterions: weak and strong coupling limits

We investigate the statistical mechanics of an inhomogeneous Coulomb fluid composed of charged particles with static polarizability. We derive the weak- and the strong-coupling approximations and evaluate the partition function in a planar dielectric slab geometry with charged boundaries. We investigate the density profiles and the disjoining pressure for both approximations. Comparison to the case of non-polarizable counterions shows that polarizability brings important differences in the counterion density distribution as well as the counterion mediated electrostatic interactions between charged dielectric interfaces.Comment: 25 pages, 7 figure

Localized collective excitations in doped graphene in strong magnetic fields

We consider collective excitations in graphene with filled Landau levels (LL’s) in the presence of an external potential due to a single charged donor D+ or acceptor A− impurity. We show that localized collective modes split off the magnetoplasmon continuum and, in addition, quasibound states are formed within the continuum. A study of the evolution of the strengths and energies of magneto-optical transitions is performed for integer filling factors ν=1,2,3,4 of the lowest LL. We predict impurity absorption peaks above as well as below the cyclotron resonance. We find that the single-particle electron-hole symmetry of graphene leads to a duality between the spectra of collective modes for the D+ and A−. The duality shows up as a set of the D+ and A− magnetoabsorption peaks having the same energies but active in different circular polarizations