Testing device subjects elastic materials to biaxial deformations

Testing device stretches elastic materials biaxially over large deformation ranges and varies strain ratios in two perpendicular directions. The device is used in conjunction with a tensile testing machine, which holds the specimen and permits control over the direction and magnitude of the stresses applied

Information Literacy in the Digital Age: Myths and Principles of Digital Literacy

Librarians have traditionally served as the champions of information literacy, adopting it as a core principle of the profession and creating a movement that tries to facilitate fair, equal access to knowledge and its creation. There are plenty of publications on this topic, but as the Information Age has become the Digital Age, there also needs to be a discussion of how information literacy is evolving. More specifically, librarians are now finding themselves shouldering the responsibilities of digital literacy alongside traditional approaches to information literacy, especially considering how more and more information needs can only be met via digital resources. This paper serves to add to this discussion by examining the different elements of the two literacies, the myths that surround them, and provide some basic principles of information literacy learning and instruction in the digital age

Ethics of e-voting: an essay on requirements and values in Internet elections

In this paper, we investigate ethical issues involved in the development and implementation of Internet voting technology. From a phenomenological perspective, we describe how voting via the Internet mediates the relation between people and democracy. In this relation, trust plays a major role. The dynamics of trust in the relation between people and their world forms the basis for our analysis of the ethical issues involved. First, we consider established principles of voting, confirming the identity of our democracy, which function as expectations in current experiments with online voting in the Netherlands. We investigate whether and how Internet voting can meet these expectations and thereby earn trust, based on the experiments in the Netherlands. We identify major challenges, and provide a basis for ethical and political discussion on these issues, especially the changed relation between public and private. If we decide that we want to vote via the Internet, more practical matters come into play in the implementation of the technology. The choices involved here are discussed in relation to the mediating role of concrete voting technologies in the relation between citizen and state

Resolving the bow-shock nebula around the old pulsar PSR B1929+10 with multi-epoch Chandra observations

We have studied the nearby old pulsar PSR B1929+10 and its surrounding interstellar medium utilizing the sub-arcsecond angular resolution of the Chandra X-ray Observatory. The Chandra data are found to be fully consistent with the results obtained from deep XMM-Newton observations as far as the pulsar is concerned. We confirm the non-thermal emission nature of the pulsar's X-radiation. In addition to the X-ray trail already seen in previous observations by the ROSAT and XMM-Newton X-ray observatories, we discovered an arc-like nebula surrounding the pulsar. We interpret the feature as a bow-shock nebula and discuss its energetics in the context of standard shock theory.Comment: Accepted by A&A, revised in accordance with referee's comment

Discovery of an X-ray Nebula associated with PSR J2124-3358

We report the discovery of an X-ray nebula associated with the nearby millisecond pulsar PSR J2124-3358. This is the first time that extended emission from a solitary millisecond pulsar is detected. The emission extends from the pulsar to the northwest by ~ 0.5 arcmin. The spectrum of the nebular emission can be modeled by a power law spectrum with photon index of 2.2 +/-0.4. This is inline with the emission being originated from accelerated particles in the post shock flow.Comment: roceedings of the 363. WE-Heraeus Seminar on: Neutron Stars and Pulsars (Posters and contributed talks) Physikzentrum Bad Honnef, Germany, May.14-19, 2006, eds. W.Becker, H.H.Huang, MPE Report 291, pp.13-1

Renormalization of the electron-phonon interaction: a reformulation of the BCS-gap equation

A recently developed renormalization approach is used to study the electron-phonon coupling in many-electron systems. By starting from an Hamiltonian which includes a small gauge symmetry breaking field, we directly derive a BCS-like equation for the energy gap from the renormalization approach. The effective electron-electron interaction for Cooper pairs does not contain any singularities. Furthermore, it is found that phonon-induced particle-hole excitations only contribute to the attractive electron-electron interaction if their energy difference is smaller than the phonon energy.Comment: 8 pages, version to appear in Eur. Phys. J.