Dialectical Spaces in the Global Public Sphere: Media Memories across Generations

A decade ago, CNN and MTV emerged as new types of 'global' players, initiating and supporting a new global transnational community of 'news junkies' and music cultures from New York, to Tokyo, to Buenos Aires and Los Angeles. Today, access to international news is not only available in many countries around the world, but international channels have multiplied and created 'imagined communities' (Anderson, 1983), affecting new political alliances, conventional journalism and - increasingly - national public spheres. The following research report will discuss new issues of globalization and focus on the impact of media-related globalization processes on 'life-worlds' in various countries

Generalized Ellipsoidal and Sphero-Conal Harmonics

Classical ellipsoidal and sphero-conal harmonics are polynomial solutions of the Laplace equation that can be expressed in terms of Lame polynomials. Generalized ellipsoidal and sphero-conal harmonics are polynomial solutions of the more general Dunkl equation that can be expressed in terms of Stieltjes polynomials. Niven's formula connecting ellipsoidal and sphero-conal harmonics is generalized. Moreover, generalized ellipsoidal harmonics are applied to solve the Dirichlet problem for Dunkl's equation on ellipsoids.Comment: This is a contribution to the Vadim Kuznetsov Memorial Issue on Integrable Systems and Related Topics, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

The Asymptotic Expansion of Kummer Functions for Large Values of the aa-Parameter, and Remarks on a Paper by Olver

It is shown that a known asymptotic expansion of the Kummer function $U(a,b,z)$ as $a$ tends to infinity is valid for $z$ on the full Riemann surface of the logarithm. A corresponding result is also proved in a more general setting considered by Olver (1956)

Evolutionary study of genus Metania GRAY, 1867 (Porifera - Spongillidae) 1. The new species

In the first paper of a series, the author describes two new species of genus Metania GRAY, 1867, starting translation into English and publication of most significant parts of her "Livre-Docência" thesis. In that thesis genus Metania was redefined and had its evolutionary inter and intrageneric lines traced upon study particularly of large collections of amazonian specimens

Photovoltaic Systems Test Facilities: Existing capabilities compilation

A general description of photovoltaic systems test facilities (PV-STFs) operated under the U.S. Department of Energy's photovoltaics program is given. Descriptions of a number of privately operated facilities having test capabilities appropriate to photovoltaic hardware development are given. A summary of specific, representative test capabilities at the system and subsystem level is presented for each listed facility. The range of system and subsystem test capabilities available to serve the needs of both the photovoltaics program and the private sector photovoltaics industry is given

Tree Parity Machine Rekeying Architectures

The necessity to secure the communication between hardware components in embedded systems becomes increasingly important with regard to the secrecy of data and particularly its commercial use. We suggest a low-cost (i.e. small logic-area) solution for flexible security levels and short key lifetimes. The basis is an approach for symmetric key exchange using the synchronisation of Tree Parity Machines. Fast successive key generation enables a key exchange within a few milliseconds, given realistic communication channels with a limited bandwidth. For demonstration we evaluate characteristics of a standard-cell ASIC design realisation as IP-core in 0.18-micrometer CMOS-technology

Dynamics of neural cryptography

Synchronization of neural networks has been used for novel public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.Comment: 9 pages, 15 figures; typos correcte

Authenticated tree parity machine key exchange

The synchronisation of Tree Parity Machines (TPMs), has proven to provide a valuable alternative concept for secure symmetric key exchange. Yet, from a cryptographer's point of view, authentication is at least as important as a secure exchange of keys. Adding an authentication via hashing e.g. is straightforward but with no relation to Neural Cryptography. We consequently formulate an authenticated key exchange within this concept. Another alternative, integrating a Zero-Knowledge protocol into the synchronisation, is also presented. A Man-In-The-Middle attack and even all currently known attacks, that are based on using identically structured TPMs and synchronisation as well, can so be averted. This in turn has practical consequences on using the trajectory in weight space. Both suggestions have the advantage of not affecting the previously observed physics of this interacting system at all.Comment: This work directly relates to cond-mat/0202112 (see also http://arxiv.org/find/cond-mat/1/au:+Kinzel/0/1/0/all/0/1

Eigenfunction expansions for a fundamental solution of Laplace's equation on R3\R^3 in parabolic and elliptic cylinder coordinates

A fundamental solution of Laplace's equation in three dimensions is expanded in harmonic functions that are separated in parabolic or elliptic cylinder coordinates. There are two expansions in each case which reduce to expansions of the Bessel functions $J_0(kr)$ or $K_0(kr)$, $r^2=(x-x_0)^2+(y-y_0)^2$, in parabolic and elliptic cylinder harmonics. Advantage is taken of the fact that $K_0(kr)$ is a fundamental solution and $J_0(kr)$ is the Riemann function of partial differential equations on the Euclidean plane

An identity of hitting times and its application to the valuation of guaranteed minimum withdrawal benefit

In this paper we explore an identity in distribution of hitting times of a finite variation process (Yor's process) and a diffusion process (geometric Brownian motion with affine drift), which arise from various applications in financial mathematics. As a result, we provide analytical solutions to the fair charge of variable annuity guaranteed minimum withdrawal benefit (GMWB) from a policyholder's point of view, which was only previously obtained in the literature by numerical methods. We also use complex inversion methods to derive analytical solutions to the fair charge of the GMWB from an insurer's point of view, which is used in the market practice, however, based on Monte Carlo simulations. Despite of their seemingly different formulations, we can prove under certain assumptions the two pricing approaches are equivalent.Comment: 25 pages, 2 figure