4,916 research outputs found
Class of Einstein--Maxwell Dilatons
Three different classes of static solutions of the Einstein--Maxwell
equations non--minimally coupled to a dilaton field are presented. The
solutions are given in general in terms of two arbitrary harmonic functions and
involve among others an arbitrary parameter which determines their
applicability as charged black holes, dilaton black holes or strings. Most of
the known solutions are contained as special cases and can be non--trivially
generalized in different ways.Comment: Published in Physical Review D, R310 (1995
Proposal to demonstrate the non-locality of Bohmian mechanics with entangled photons
Bohmian mechanics reproduces all statistical predictions of quantum
mechanics, which ensures that entanglement cannot be used for superluminal
signaling. However, individual Bohmian particles can experience superluminal
influences. We propose to illustrate this point using a double double-slit
setup with path-entangled photons. The Bohmian velocity field for one of the
photons can be measured using a recently demonstrated weak-measurement
technique. The found velocities strongly depend on the value of a phase shift
that is applied to the other photon, potentially at spacelike separation.Comment: 6 pages, 4 figure
Rotating Dilaton Black Holes
It is shown that an arbitrarily small amount of angular momentum can
qualitatively change the properties of extremal charged black holes coupled to
a dilaton. In addition, the gyromagnetic ratio of these black holes is computed
and an exact rotating black string solution is presented.Comment: 14 page
Sports mega-events – three sites of contemporary political contestation
This article discusses the contemporary politics of sports mega-events, involving the Olympic Games and Fédération Internationale de Football Association (FIFA) Men’s Football World Cup Finals as well as other lower ‘order’ sports megas, taking two main forms: the promotional and the protest. There is a politics in, and a politics of, sports mega-events. The former focuses on the internal politics of the organizing bodies, such as the International Olympic Committee and FIFA. This form of politics has been written about elsewhere, and hence, there is no detailed discussion in this article about it. Instead this article offers a brief discussion of the range and number of sports mega-events since 2000, an assessment of the contemporary politics of sports mega-events, a focus on three main sites of political contestation – rights, legacy and labour, and finally, it offers conclusions about research into the politics of sports mega-events
The role of virtual reality in built environment education
This study builds upon previous research on the integration of Virtual Reality (VR) within the built environment curriculum and aims to investigate the role of VR and three-dimensional (3D) computer modelling on learning and teaching in a school of the built environment. In order to achieve this aim, a number of academic experiences were analysed to explore the applicability and viability of 3D computer modelling and VR into built environment subject areas. Although two-dimensional (2D) representations have been greatly accepted by built environment professions and education, 3D computer representations and VR applications, offering interactivity and immersiveness, are not yet widely accepted. The study attempts to understand the values and challenges of integrating visualisation technologies into built environment teaching and investigates tutors’ perceptions, opinions and concerns with respect to these technologies. The study reports on the integration process and considers how 3D computer modelling and VR technologies can combine with, and extend, the existing range of learning and teaching methods appropriate to different disciplines and programme areas
Functional neuroimaging and withdrawal of life-sustaining treatment from vegetative patients
Recent studies using functional magnetic resonance imaging of patients in a vegetative state have raised the possibility that such patients retain some degree of consciousness. In this paper, the ethical implications of such findings are outlined, in particular in relation to decisions about withdrawing life-sustaining treatment. It is sometimes assumed that if there is evidence of consciousness, treatment should not be withdrawn. But, paradoxically, the discovery of consciousness in very severely brain-damaged patients may provide more reason to let them die. Although functional neuroimaging is likely to play an increasing role in the assessment of patients in a vegetative state, caution is needed in the interpretation of neuroimaging findings
Colliding Plane Waves in Einstein-Maxwell-Dilaton Fields
Within the metric structure endowed with two orthogonal space-like Killing
vectors a class of solutions of the Einstein-Maxwell-Dilaton field equations is
presented. Two explicitly given sub-classes of solutions bear an interpretation
as colliding plane waves in the low-energy limit of the heterotic string
theory.Comment: 14 pages, LaTex; To appear in Phys. Rev.
On the mass of the neutron star in Cyg X-2
We present new high resolution spectroscopy of the low mass X-ray binary Cyg
X-2 which enables us to refine the orbital solution and rotational broadening
of the donor star. In contrast with Elebert et al (2009) we find a good
agreement with results reported in Casares et al. (1998). We measure
day, km s and km s. These values imply and
M (for ). Therefore, the
neutron star in Cyg X-2 can be more massive than canonical. We also find no
evidence for irradiation effects in our radial velocity curve which could
explain the discrepancy between Elebert et al's and our values.Comment: Accepted for publication in MNRA
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