11,017 research outputs found
The Impact of Dispersal Powers on Congregating Youth
Purpose: To present research which evaluated the impact of Dispersal Orders in an English town. Design/Methodology/Approach: The study used a mixed method design to, qualitatively, explore the impact of the intervention on young people and, quantitatively, the impact on recorded crime/anti-social behaviour. Findings: The use of Dispersal Orders in the town being studied highlighted a number of issues detrimental to young people. Powers appeared to be used to control the congregating rather than anti-social behaviour of young people and their use could increase young peoples’ feelings of vulnerability. Practical Implications: The findings suggest that Dispersal Orders (and the newer Public Spaces Protection Orders) may be ineffective if they are used without the focus of a specific anti-social behaviour issue. Social Implications: The findings suggest that the use of Dispersal Orders to deal with non anti-social behaviour issues are likely to alienate young people and have the potential to inadvertently place them at further risk. They also suggest that the Public Spaces Protection Order could very well exacerbate the substantial issues which have been identified in the present research. Originality/Value: This research is original and suggests that the negative findings of earlier pieces of research into Dispersal Orders can be replicated in very different geographical environments and in areas with low levels of general deprivation where no substantial anti-social behaviour issues were identified. Furthermore, it uses original data to contextualise contemporary developments in anti-social behaviour, namely the introduction of Public Spaces Protection Order
Pore-scale Modeling of Viscous Flow and Induced Forces in Dense Sphere Packings
We propose a method for effectively upscaling incompressible viscous flow in
large random polydispersed sphere packings: the emphasis of this method is on
the determination of the forces applied on the solid particles by the fluid.
Pore bodies and their connections are defined locally through a regular
Delaunay triangulation of the packings. Viscous flow equations are upscaled at
the pore level, and approximated with a finite volume numerical scheme. We
compare numerical simulations of the proposed method to detailed finite element
(FEM) simulations of the Stokes equations for assemblies of 8 to 200 spheres. A
good agreement is found both in terms of forces exerted on the solid particles
and effective permeability coefficients
Excitons in T-shaped quantum wires
We calculate energies, oscillator strengths for radiative recombination, and
two-particle wave functions for the ground state exciton and around 100 excited
states in a T-shaped quantum wire. We include the single-particle potential and
the Coulomb interaction between the electron and hole on an equal footing, and
perform exact diagonalisation of the two-particle problem within a finite basis
set. We calculate spectra for all of the experimentally studied cases of
T-shaped wires including symmetric and asymmetric GaAs/AlGaAs and
InGaAs/AlGaAs structures. We study in detail the
shape of the wave functions to gain insight into the nature of the various
states for selected symmetric and asymmetric wires in which laser emission has
been experimentally observed. We also calculate the binding energy of the
ground state exciton and the confinement energy of the 1D quantum-wire-exciton
state with respect to the 2D quantum-well exciton for a wide range of
structures, varying the well width and the Al molar fraction . We find that
the largest binding energy of any wire constructed to date is 16.5 meV. We also
notice that in asymmetric structures, the confinement energy is enhanced with
respect to the symmetric forms with comparable parameters but the binding
energy of the exciton is then lower than in the symmetric structures. For
GaAs/AlGaAs wires we obtain an upper limit for the binding energy
of around 25 meV in a 10 {\AA} wide GaAs/AlAs structure which suggests that
other materials must be explored in order to achieve room temperature
applications. There are some indications that
InGaAs/AlGaAs might be a good candidate.Comment: 20 pages, 10 figures, uses RevTeX and psfig, submitted to Physical
Review
Molecular gas in nearby powerful radio galaxies
We report the detection of CO(1-0) and CO(2-1) emission from the central
region of nearby 3CR radio galaxies (z 0.03). Out of 21 galaxies, 8 have
been detected in, at least, one of the two CO transitions. The total molecular
gas content is below 10 \msun. Their individual CO emission exhibit, for 5
cases, a double-horned line profile that is characteristic of an inclined
rotating disk with a central depression at the rising part of its rotation
curve. The inferred disk or ring distributions of the molecular gas is
consistent with the observed presence of dust disks or rings detected optically
in the cores of the galaxies. We reason that if their gas originates from the
mergers of two gas-rich disk galaxies, as has been invoked to explain the
molecular gas in other radio galaxies, then these galaxies must have merged a
long time ago (few Gyr or more) but their remnant elliptical galaxies only
recently (last 10 years or less) become active radio galaxies. Instead, we
argue the the cannibalism of gas-rich galaxies provide a simpler explanation
for the origin of molecular gas in the elliptical hosts of radio galaxies (Lim
et al. 2000). Given the transient nature of their observed disturbances, these
galaxies probably become active in radio soon after the accretion event when
sufficient molecular gas agglomerates in their nuclei.Comment: 6 pages, including 2 figures,in "QSO Hosts and Their Environments",
ed. I. Marquez, in pres
Magnetoelectric coupling in a frustrated spinel studied using high-field scanning probe microscopy
Below its N\'eel temperature, the frustrated magnet CdCrO exhibits an
antiferromagnetic spin-spiral ground state. Such states can give rise to a
sizable magnetoelectric coupling. In this report, we measure the electric
polarization induced in single-crystalline CdCrO by a large applied
magnetic field. Because the detection of a macroscopic polarization is hindered
by the structural domains in the tetragonal spin-spiral phase, we have
pioneered an alternative method of measuring polarization induced by high
magnetic fields, using electrostatic force microscopy. This method enables us
to measure polarization from nanometer sized areas of the sample surface, as
well as imaging how to charge inhomogeneities change with magnetic field.Comment: 5 pages, 3 figure
Willmore Surfaces of Constant Moebius Curvature
We study Willmore surfaces of constant Moebius curvature in . It is
proved that such a surface in must be part of a minimal surface in
or the Clifford torus. Another result in this paper is that an isotropic
surface (hence also Willmore) in of constant could only be part of a
complex curve in or the Veronese 2-sphere in . It is
conjectured that they are the only examples possible. The main ingredients of
the proofs are over-determined systems and isoparametric functions.Comment: 16 pages. Mistakes occured in the proof to the main theorem (Thm 3.6)
has been correcte
Ariation in Tannin Content and Morphological Traits in \u3ci\u3eLotus corniculatus\u3c/i\u3e L. (Bird’s-Foot Trefoil)
Lotus corniculatus L. (bird\u27s-foot trefoil) is a potentially valuable species for UK grassland agriculture. The herbage contains proanthocyanidins, or condensed tannins (CT\u27s), which help to reduce bloat, have anthelmintic properties, can protect protein in the rumen, and thus potentially reduce N losses to the environment. It is currently a relatively minor species within UK grassland, as available varieties lack persistence in mixed swards (Hopkins et al., 1996). The seed used is of foreign bred varieties with no varieties bred specifically for the UK environment. To explore the feasibility of breeding L. corniculatus for the UK, variation in morphological traits, dry matter yield and tannin content within existing varieties was measured
Self-Duality in D <= 8-dimensional Euclidean Gravity
In the context of D-dimensional Euclidean gravity, we define the natural
generalisation to D-dimensions of the self-dual Yang-Mills equations, as
duality conditions on the curvature 2-form of a Riemannian manifold. Solutions
to these self-duality equations are provided by manifolds of SU(2), SU(3), G_2
and Spin(7) holonomy. The equations in eight dimensions are a master set for
those in lower dimensions. By considering gauge fields propagating on these
self-dual manifolds and embedding the spin connection in the gauge connection,
solutions to the D-dimensional equations for self-dual Yang-Mills fields are
found. We show that the Yang-Mills action on such manifolds is topologically
bounded from below, with the bound saturated precisely when the Yang-Mills
field is self-dual. These results have a natural interpretation in
supersymmetric string theory.Comment: 9 pages, Latex, factors in eqn. (6) corrected, acknowledgement and
reference added, typos fixe
Influence of chromophores on quarternary structure of phycobiliproteins from the cyanobacterium, Mastigocladus laminosus
Chromophores of C-phycocyanin and phycoerythrο-cyanin have been chemically modified by reduction to
rubins , bleaching , photoisomerization , or perturbation
with bulky substituents. Pigments containing modified
chromophores, or hybrids containing modified and unmodified chromophores in individual protomers have been prepared. All modifications inhibit the association of the
(aß)-protomers of these pigments to higher aggregates. The
results demonstrate a pronounced effect of the state of
the chromophores on biliprotein quaternary structure. It
may be important in phycobi1isome assembly , and also in
the dual function of biliproteins as (i) antenna pigments
for photosynthesis and (ii) reaction centers for photomor-phogenesis
A natural Finsler--Laplace operator
We give a new definition of a Laplace operator for Finsler metric as an
average with regard to an angle measure of the second directional derivatives.
This definition uses a dynamical approach due to Foulon that does not require
the use of connections nor local coordinates. We show using 1-parameter
families of Katok--Ziller metrics that this Finsler--Laplace operator admits
explicit representations and computations of spectral data.Comment: 25 pages, v2: minor modifications, changed the introductio
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