Enumeration of Hypermaps of a Given Genus

This paper addresses the enumeration of rooted and unrooted hypermaps of a given genus. For rooted hypermaps the enumeration method consists of considering the more general family of multirooted hypermaps, in which darts other than the root dart are distinguished. We give functional equations for the generating series counting multirooted hypermaps of a given genus by number of darts, vertices, edges, faces and the degrees of the vertices containing the distinguished darts. We solve these equations to get parametric expressions of the generating functions of rooted hypermaps of low genus. We also count unrooted hypermaps of given genus by number of darts, vertices, hyperedges and faces.Comment: 42 page

Soliton-comb structures in ring-shaped optical microresonators: generation, reconstruction and stability

Characteristic features of soliton-comb structures in optical microresonators are investigated in normal and anomalous dispersion regimes, when the detuning parameter is varied over a broad range of values. The study rests on the assumption that soliton combs are self-organized ensemble of co-propagating coherently entangled states of light, and depending on the group-velocity dispersion they can result from space-division multiplexing of single-bright and single-dark solitons. Their analytical and numerical reconstruction schemes are discussed, while a linear-stability analysis leads to a $2\times 2$ Lam\'e eigenvalue problem whose boundstate spectrum is composed of a Goldstone-type translation mode and stable internal modes, as well as unstable decaying modes and growing modes. A power-spectral analysis of the three distinct possible soliton crystals enables us probe their inner structures in the frequency domain, and unveil the existence of structural defects in their power spectra.Comment: 19 pages, 9 figures, submitte

The bribery paradox in transition economies and the enactment of ‘new normal’ business environments

We develop a novel, sensemaking perspective on corruption in transition economies. Prior research has focused on understanding why some entrepreneurs are more likely to pay bribes than others. It typically assumes that paying bribes will lead to an intended – albeit unfair – competitive advantage. We challenge this assumption and uncover a bribery paradox: drawing upon sensemaking logic, we argue that beyond gaining an immediate benefit from bribing, entrepreneurs who frequently pay bribes may in the longer run be enacting a ‘new normal’ business environment perceived as high in obstacles, especially in transition countries. As sensemaking is grounded in identity construction and one’s social context, we argue that owners of family firms will be especially vulnerable to the dangers of perceiving greater obstacles over time and enacting an obstacle‐ridden ‘new normal’ business environment. We find empirical support for our framework on a sample of 310 privately‐held small and medium‐sized enterprises (SMEs) from 22 transition economies

Detection of Change--Points in the Spectral Density. With Applications to ECG Data

We propose a new method for estimating the change-points of heart rate in the orthosympathetic and parasympathetic bands, based on the wavelet transform in the complex domain and the study of the change-points in the moments of the modulus of these wavelet transforms. We observe change-points in the distribution for both bands.Comment: proceeding of the workshop 'Fouille de donn\'ees temporelles et analyse de flux de donn\'ees' EGC'2009, january 27, Strasbourg, Franc

Narrow-band noise due to the moving vortex lattice in superconducting niobium

We report measurements of voltage noise due to vortex motion in Niobium, a conventional low-Tc superconductor. A coherent oscillation leading to narrow band noise (NBN) is evidenced. Its characteristic frequency is a linear function of the overcritical transport current in the flux-flow regime, and hence scales as the main velocity of the vortex flow. The associated length scale is not the intervortex distance but the width of the sample, indicating temporal coherence at a large scale. NBN is also observed in the non linear part of the V(I) at the onset of depinning, in apparent disagreement with a stochastic creep motion of flux bundles. NBN exists in the peak effect region, showing that long range temporal correlations are preserved in this regime.Comment: accepted for publication in Phys Rev

Relativistic Quasilinear Diffusion in Axisymmetric Magnetic Geometry for Arbitrary-Frequency Electromagnetic Fluctuations

A relativistic bounce-averaged quasilinear diffusion equation is derived to describe stochastic particle transport associated with arbitrary-frequency electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for the elements of a relativistic quasilinear diffusion tensor are calculated explicitly for magnetically-trapped particle distributions in axisymmetric magnetic geometry in terms of gyro-drift-bounce wave-particle resonances. The resonances can destroy any one of the three invariants of the unperturbed guiding-center Hamiltonian dynamics.Comment: 22 pages, Latex, to appear in Physics of Plasma