1,062 research outputs found
Neutrino telescope modelling of Lorentz invariance violation in oscillations of atmospheric neutrinos
One possible feature of quantum gravity may be the violation of Lorentz invariance. In this paper, we consider one particular manifestation of the violation of Lorentz invariance, namely modified dispersion relations for massive neutrinos. We show how such modified dispersion relations may affect atmospheric neutrino oscillations. We then consider how neutrino telescopes, such as ANTARES, may be able to place bounds on the magnitude of this type of Lorentz invariance violation
Quantum Decoherence in a Four-Dimensional Black Hole Background
We display a logarithmic divergence in the density matrix of a scalar field
in the presence of an Einstein-Yang-Mills black hole in four dimensions. This
divergence is related to a previously-found logarithmic divergence in the
entropy of the scalar field, which cannot be absorbed into a renormalization of
the Hawking-Bekenstein entropy of the black hole. As the latter decays, the
logarithmic divergence induces a non-commutator term \nd{\delta H}\rho in the
quantum Liouville equation for the density matrix of the scalar field,
leading to quantum decoherence. The order of magnitude of \nd{\delta H} is
, where is the mass of the scalar particle.Comment: 13-pages LATE
Comparison of mercury in atmospheric deposition and in Illinois and USA soils
International audienceIt has been reported that most mercury (Hg) in USA soils is from atmospheric Hg deposition, mostly from anthropogenic sources. This paper compares the rates of atmospheric Hg deposition to amounts of Hg in Illinois and USA soils. The amounts of Hg in these soils are too great to be attributed mainly to anthropogenic atmospheric Hg deposition. Keywords: mercury, atmospheric deposition, soil, geology, Illinois, US
A descriptive literature review of Recognition of Prior Learning for vocational learners in emergency medical care in South Africa
Radical advances in emergency medical care education in South Africa have resulted in both advancements and suppression. After short-course vocational training, the emergency care provider could seek employment in an emergency service. With the realignment of emergency medical care programmes to the National Qualifications Framework (NQF), these short vocational courses were phased out by 2018. Although necessary for educational advancement, these changes prevented vocationally trained emergency care providers from articulating into higher education without returning to full-time academia. Moreover, despite recognition of prior learning (RPL) policies in higher education, few institutes offering emergency medical care programmes offered this as an access option.
This descriptive literature review aimed to analyse the RPL processes in South Africa and globally. Additionally, insight into RPL candidates” support requirements for postgraduate studies was gained. A systematic search of peer-reviewed journal articles, periodicals, dissertations, and governmental reports from 2000 to 2021 was conducted. Various databases were accessed, including Proquest, EBSCOhost, LearnTechLib, JSTOR, ERIC, Google Scholar, and the Thesis Repository. The lack of literature focusing on the prehospital RPL system in South Africa prompted search expansions into the field of health science internationally. Of the 401 screened sources, 19 met the researcher’s inclusion criteria. Two additional articles were sourced in a repeated search in February 2022. The findings revealed enablers and barriers for RPL students and expanded on their personal and academic transitions. The themes identified through the enablers and barriers can assist in identifying additional support for RPL students during their educational journey. Ultimately, despite vital institutional transitions in RPL processes, intrinsic motivation inspired these students to embrace the challenges they faced, and their process of personal transition and lifelong learning began
Characterizing asymptotically anti-de Sitter black holes with abundant stable gauge field hair
In the light of the "no-hair" conjecture, we revisit stable black holes in
su(N) Einstein-Yang-Mills theory with a negative cosmological constant. These
black holes are endowed with copious amounts of gauge field hair, and we
address the question of whether these black holes can be uniquely characterized
by their mass and a set of global non-Abelian charges defined far from the
black hole. For the su(3) case, we present numerical evidence that stable black
hole configurations are fixed by their mass and two non-Abelian charges. For
general N, we argue that the mass and N-1 non-Abelian charges are sufficient to
characterize large stable black holes, in keeping with the spirit of the
"no-hair" conjecture, at least in the limit of very large magnitude
cosmological constant and for a subspace containing stable black holes (and
possibly some unstable ones as well).Comment: 33 pages, 13 figures, minor change
Geon black holes and quantum field theory
Black hole spacetimes that are topological geons in the sense of Sorkin can
be constructed by taking a quotient of a stationary black hole that has a
bifurcate Killing horizon. We discuss the geometric properties of these geon
black holes and the Hawking-Unruh effect on them. We in particular show how
correlations in the Hawking-Unruh effect reveal to an exterior observer
features of the geometry that are classically confined to the regions behind
the horizons.Comment: 11 pages. Talk given at the First Mediterranean Conference on
Classical and Quantum Gravity, Kolymbari (Crete, Greece), September 2009.
Dedicated to Rafael Sorkin. v2: typesetting bug fixe
Case Study: Cancrum oris (noma) in a malnourished HIV-positive child from rural Kwazulu-Natal
Cancrum oris (noma – derived from the Greek nomein, ‘to devour\') is an infectious disease with a fulminating course that destroys the oro-facial tissues and other neighbouring structures.1 Although cancrum oris can occur at any age, it is most commonly in malnourished children between the ages of 1 and 5 years whose general health has been further weakened by some infectious disease, usually measles but also tuberculosis, gastro-enteritis, typhoid, whooping cough, or malignant disease such as leukaemia. The possible relevance to HIV has not been fully investigated. This report details a case presenting to East Griqualand and Usher Memorial Hospital, Kokstad, KwaZulu-Natal.
Southern African Journal of HIV Medicine Vol. 5 (3) 2004: 45-4
Probing quantum decoherence in atmospheric neutrino oscillations with a neutrino telescope
Quantum decoherence, the evolution of pure states into mixed states, may be a feature of quantum gravity. In this paper, we show how these effects can be modelled for atmospheric neutrinos and illustrate how the standard oscillation picture is modified. We examine how neutrino telescopes, such as ANTARES, are able to place upper bounds on these quantum decoherence effects
Decoherent Scattering of Light Particles in a D-Brane Background
We discuss the scattering of two light particles in a D-brane background. It
is known that, if one light particle strikes the D brane at small impact
parameter, quantum recoil effects induce entanglement entropy in both the
excited D brane and the scattered particle. In this paper we compute the
asymptotic `out' state of a second light particle scattering off the D brane at
large impact parameter, showing that it also becomes mixed as a consequence of
quantum D-brane recoil effects. We interpret this as a non-factorizing
contribution to the superscattering operator S-dollar for the two light
particles in a Liouville D-brane background, that appears when quantum D-brane
excitations are taken into account.Comment: 18 pages LATEX, one figure (incorporated
Instability of a four-dimensional de Sitter black hole with a conformally coupled scalar field
We study the stability of new neutral and electrically charged
four-dimensional black hole solutions of Einstein's equations with a positive
cosmological constant and conformally coupled scalar field. The neutral black
holes are always unstable. The charged black holes are also shown analytically
to be unstable for the vast majority of the parameter space of solutions, and
we argue using numerical techniques that the configurations corresponding to
the remainder of the parameter space are also unstable.Comment: revtex4, 8 pages, 4 figures, minor changes, accepted for publication
in Phys. Rev.
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