17,676 research outputs found
Investigating risk and protective factors to mainstream safety and peace at the University of South Africa
Given the high fatality rates resulting from both unintentional and intentional injuries in South Africa, the identification and prevention of risk factors resulting in injurious incidents as well as the promotion of protective factors is central to the country’s research agenda. While social science and public health enquiries apply these objectives to various South African contexts, few studies investigate manifest risk and protective factors within South African universities. Accordingly, this study aims to develop the first record of both risk and protective factors at the University of South Africa (Unisa) Muckleneuk Campus as a means to inform future theoretical and practical initiatives in the area. Data was collected with photo-documentaries, unobtrusive field observations, and a peace and safety checklist. The collated data was subjected to a thematic content analysis, allowing for the emergence of four distinct peace and safety promotion themes. These themes include crime, fire injury and electrocution, road and traffic injury, in addition to unintentional injuries. These four themes are discussed, and recommendations are provided, with the intention of informing injury prevention and safety promotion initiatives at the level of both theory and practice in South African tertiary education contexts. This study provides a platform upon which further work in the field can be produced to ensure the safety of students attending tertiary education institutions in South Africa.Keywords: campus safety; crime; traffic; electrocution; injury; South Africa; Unis
Current-voltage characteristics of quasi-one-dimensional superconductors: An S-curve in the constant voltage regime
Applying a constant voltage to superconducting nanowires we find that its
IV-characteristic exhibits an unusual S-behavior. This behavior is the direct
consequence of the dynamics of the superconducting condensate and of the
existence of two different critical currents: j_{c2} at which the pure
superconducting state becomes unstable and j_{c1}<j_{c2} at which the phase
slip state is realized in the system.Comment: 4 pages, 5 figures, replaced with minor change
Generalizing the DGLAP Evolution of Fragmentation Functions to the Smallest x Values
An approach which unifies the Double Logarithmic Approximation at small x and
the leading order DGLAP evolution of fragmentation functions at large x is
presented. This approach reproduces exactly the Modified Leading Logarithm
Approximation, but is more complete due to the degrees of freedom given to the
quark sector and the inclusion of the fixed order terms. We find that data from
the largest x values to the peak region can be better fitted than with other
approaches.Comment: 10 pages, 3 figure
Information Content in Decays and the Angular Moments Method
The time-dependent angular distributions of decays of neutral mesons into
two vector mesons contain information about the lifetimes, mass differences,
strong and weak phases, form factors, and CP violating quantities. A
statistical analysis of the information content is performed by giving the
``information'' a quantitative meaning. It is shown that for some parameters of
interest, the information content in time and angular measurements combined may
be orders of magnitude more than the information from time measurements alone
and hence the angular measurements are highly recommended. The method of
angular moments is compared with the (maximum) likelihood method to find that
it works almost as well in the region of interest for the one-angle
distribution. For the complete three-angle distribution, an estimate of
possible statistical errors expected on the observables of interest is
obtained. It indicates that the three-angle distribution, unraveled by the
method of angular moments, would be able to nail down many quantities of
interest and will help in pointing unambiguously to new physics.Comment: LaTeX, 34 pages with 9 figure
Photon rockets and gravitational radiation
The absence of gravitational radiation in Kinnersley's ``photon rocket''
solution of Einstein's equations is clarified by studying the mathematically
well-defined problem of point-like photon rockets in Minkowski space (i.e.
massive particles emitting null fluid anisotro\-pically and accelerating
because of the recoil). We explicitly compute the (uniquely defined) {\it
linearized} retarded gravitational waves emitted by such objects, which are the
coherent superposition of the gravitational waves generated by the motion of
the massive point-like rocket and of those generated by the energy-momentum
distribution of the photon fluid. In the special case (corresponding to
Kinnersley's solution) where the anisotropy of the photon emission is purely
dipolar we find that the gravitational wave amplitude generated by the
energy-momentum of the photons exactly cancels the usual gravitational
wave amplitude generated by the accelerated motion of the rocket. More general
photon anisotropies would, however, generate genuine gravitational radiation at
infinity. Our explicit calculations show the compatibility between the
non-radiative character of Kinnersley's solution and the currently used
gravitational wave generation formalisms based on post-Minkowskian perturbation
theory.Comment: 21 pages, LATEX, submitted to Class. Quant. Gra
Influence of Vertical Ground Motions on the Seismic Fragility Modeling of a Bridge-Soil-Foundation System
This paper explores the effects of vertical ground motions (VGMs) on the
component fragility of a coupled bridged-soil-foundation (CBSF) system with
liquefaction potential, and highlights the unique considerations on the demand
and capacity model required for fragility analysis under VGMs. Optimal intensity
measures (IMs) that account for VGMs are identified. Moreover, fragility curves
that consider capacity change with fluctuating axial force are derived. Results
show that the presence of VGMs has a minor effect on the failure probabilities
of piles and expansion bearings, while it has a great influence on fixed bearings.
Whether VGMs have an impact on column fragilities depends on the design axial
load ratio. Finally, more accurate fragility surfaces are derived, which are compared
with results of conventional fragility curves. This study highlights the
important role that VGMs play in the selection of optimal IMs, and the capacity
and fragility representation of certain components of CBSF systems
The effect of magnetic field and disorders on the electronic transport in graphene nanoribbons
We developed a unified mesoscopic transport model for graphene nanoribbons,
which combines the non-equilibrium Green's function (NEGF) formalism with the
real-space {\pi}-orbital model. Based on this model, we probe the spatial
distributions of electrons under a magnetic field, in order to obtain insights
into the various signature Hall effects in disordered armchair graphene
nanoribbons (AGNR). In the presence of a uniform perpendicular magnetic field
(B\perp-field), a perfect AGNR shows three distinct spatial current profiles at
equilibrium, depending on its width. Under non-equilibrium conditions (i.e. in
the presence of an applied bias), the net electron flow is restricted to the
edges and occurs in opposite directions depending on whether the Fermi level
lies within the valence or conduction band. For electrons at energy level below
the conduction window, the B\perp-field gives rise to local electron flux
circulation, although the global flux is zero. Our study also reveals the
suppression of electron backscattering as a result of the edge transport which
is induced by the B\perp-field. This phenomenon can potentially mitigate the
undesired effects of disorders, such as the bulk and edge vacancies, on the
transport properties of AGNR. Lastly, we show that the effect of B\perp-field
on electronic transport is less significant in the multimode compared to the
single mode electron transport.Comment: 21 pages, 4 figure
Using participatory and creative methods to facilitate emancipatory research with people facing multiple disadvantage: a role for health and care professionals
Participatory and creative research methods are a powerful tool for enabling active engagement in the research process of marginalised people. It can be particularly hard for people living with multiple disadvantage, such as disabled people from ethnic minority backgrounds, to access research projects that are relevant to their lived experience. This article argues that creative and participatory methods facilitate the co-researchers’ engagement in the research process, which thus becomes more empowering. Exploring the congruence of these methods with their professional ethos, health and care professionals can use their skills to develop them further. Both theory and practice examples are presented
Cherenkov radiation in a gravitational wave background
A covariant criterion for the Cherenkov radiation emission in the field of a
non-linear gravitational wave is considered in the framework of exact
integrable models of particle dynamics and electromagnetic wave propagation. It
is shown that vacuum interacting with curvature can give rise to Cherenkov
radiation. The conically shaped spatial distribution of radiation is derived
and its basic properties are discussed.Comment: LaTeX file, no figures, 19 page
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