228 research outputs found
Exact eigenvalue spectrum of a class of fractal scale-free networks
The eigenvalue spectrum of the transition matrix of a network encodes
important information about its structural and dynamical properties. We study
the transition matrix of a family of fractal scale-free networks and
analytically determine all the eigenvalues and their degeneracies. We then use
these eigenvalues to evaluate the closed-form solution to the eigentime for
random walks on the networks under consideration. Through the connection
between the spectrum of transition matrix and the number of spanning trees, we
corroborate the obtained eigenvalues and their multiplicities.Comment: Definitive version accepted for publication in EPL (Europhysics
Letters
First Passage Properties of the Erdos-Renyi Random Graph
We study the mean time for a random walk to traverse between two arbitrary
sites of the Erdos-Renyi random graph. We develop an effective medium
approximation that predicts that the mean first-passage time between pairs of
nodes, as well as all moments of this first-passage time, are insensitive to
the fraction p of occupied links. This prediction qualitatively agrees with
numerical simulations away from the percolation threshold. Near the percolation
threshold, the statistically meaningful quantity is the mean transit rate,
namely, the inverse of the first-passage time. This rate varies
non-monotonically with p near the percolation transition. Much of this behavior
can be understood by simple heuristic arguments.Comment: 10 pages, 9 figures, 2-column revtex4 forma
Multiphoton radiative recombination of electron assisted by laser field
In the presence of an intensive laser field the radiative recombination of
the continuum electron into an atomic bound state generally is accompanied by
absorption or emission of several laser quanta. The spectrum of emitted photons
represents an equidistant pattern with the spacing equal to the laser
frequency. The distribution of intensities in this spectrum is studied
employing the Keldysh-type approximation, i.e. neglecting interaction of the
impact electron with the atomic core in the initial continuum state. Within the
adiabatic approximation the scale of emitted photon frequencies is subdivided
into classically allowed and classically forbidden domains. The highest
intensities correspond to emission frequencies close to the edges of
classically allowed domain. The total cross section of electron recombination
summed over all emitted photon channels exhibits negligible dependence on the
laser field intensity.Comment: 14 pages, 5 figures (Figs.2-5 have "a" and "b" parts), Phys.Rev.A
accepted for publication. Fig.2b is presented correctl
Networking - A Statistical Physics Perspective
Efficient networking has a substantial economic and societal impact in a
broad range of areas including transportation systems, wired and wireless
communications and a range of Internet applications. As transportation and
communication networks become increasingly more complex, the ever increasing
demand for congestion control, higher traffic capacity, quality of service,
robustness and reduced energy consumption require new tools and methods to meet
these conflicting requirements. The new methodology should serve for gaining
better understanding of the properties of networking systems at the macroscopic
level, as well as for the development of new principled optimization and
management algorithms at the microscopic level. Methods of statistical physics
seem best placed to provide new approaches as they have been developed
specifically to deal with non-linear large scale systems. This paper aims at
presenting an overview of tools and methods that have been developed within the
statistical physics community and that can be readily applied to address the
emerging problems in networking. These include diffusion processes, methods
from disordered systems and polymer physics, probabilistic inference, which
have direct relevance to network routing, file and frequency distribution, the
exploration of network structures and vulnerability, and various other
practical networking applications.Comment: (Review article) 71 pages, 14 figure
Role of electromagnetically induced transparency in resonant four-wave-mixing schemes.
Published versio
Political branding: sense of identity or identity crisis? An investigation of the transfer potential of the brand identity prism to the UK Conservative Party
Brands are strategic assets and key to achieving a competitive advantage. Brands can be seen as a heuristic device, encapsulating a series of values that enable the consumer to make quick and efficient choices. More recently, the notion of a political brand and the rhetoric of branding have been widely adopted by many political parties as they seek to differentiate themselves, and this has led to an emerging interest in the idea of the political brand. Therefore, this paper examines the UK Conservative Party brand under David Cameron’s leadership and examines the applicability of Kapferer’s brand identity prism to political branding. This paper extends and operationalises the brand identity prism into a ‘political brand identity network’ which identifies the inter-relatedness of the components of the corporate political brand and the candidate political brand. Crucial for practitioners, this model can demonstrate how the brand is presented and communicated to the electorate and serves as a useful mechanism to identify consistency within the corporate and candidate political brands
Organisational culture of further education colleges delivering higher education business programmes: developing a culture of ‘HEness’ – what next?
This paper draws on the views of lecturers working in and delivering college-based higher education (CBHE) in the UK. There have been numerous works on the culture of higher education in further education (HE in FE). However, as noted by some literati, the culture of further education (FE) is not easy to define, and does not readily lend itself to the incorporation of a higher education (HE) culture. This could be due to the large number of changes FE has had to adopt owing to various government policies. The study comprises 26 in-depth individual interviews conducted at various further education colleges throughout the Yorkshire and Humber region of the UK. Via the use of an interpretivist approach, common themes and word use were extracted from the narratives for analysis. The organisational culture of these further education colleges was relatively easy to define, the word ‘blame’ being one of the common themes. However, when identifying if the individual colleges had a HE culture; this proved more difficult
Exit and Occupation times for Brownian Motion on Graphs with General Drift and Diffusion Constant
We consider a particle diffusing along the links of a general graph
possessing some absorbing vertices. The particle, with a spatially-dependent
diffusion constant D(x) is subjected to a drift U(x) that is defined in every
point of each link. We establish the boundary conditions to be used at the
vertices and we derive general expressions for the average time spent on a part
of the graph before absorption and, also, for the Laplace transform of the
joint law of the occupation times. Exit times distributions and splitting
probabilities are also studied and several examples are discussed.Comment: Accepted for publication in J. Phys.
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