8,999 research outputs found
Outsider and Insider Expertise: The response of residents of deprived neighbourhoods to an academic definition of social exclusion
The aim of this paper is to compare academic interpretations of the term social exclusion with the understanding of people with direct experience of the phenomenon. A pre-selected group of residents of deprived neighbourhoods were asked about various aspects of the concept and their responses compared with the definitions of social exclusion used by Burchardt, Le Grand and Piachaud in their 1999 article in the journal Social Policy and Administration. In general, the residents' understanding of the term corresponded well with the more academic definitions; however, in one or two key areas there were significant differences, for example, the importance of neighbourhood and 'service poverty', and the need for action against aspects of social exclusion on the grounds of social justice. This confirms that it might be useful for more academic concepts to be tested against the views of those with experience of the phenomenon which the concept is trying to capture.definitions of social exclusion, community involvement, neighbourhood renewal
Tame group actions on central simple algebras
We study actions of linear algebraic groups on finite-dimensional central
simple algebras. We describe the fixed algebra for a broad class of such
actions.Comment: 19 pages, LaTeX; slightly revised; final version will appear in
Journal of Algebr
Recovery of 150-250 MeV/nuc Cosmic Ray Helium Nuclei Intensities Between 2004-2010 Near the Earth, at Voyager 2 and Voyager 1 in the Heliosheath - A Two Zone Helioshpere
The recovery of cosmic ray He nuclei of energy ~150-250 MeV/nuc in solar
cycle #23 from 2004 to 2010 has been followed at the Earth using IMP and ACE
data and at V2 between 74-92 AU and also at V1 beyond the heliospheric
termination shock (91-113 AU). The correlation coefficient between the
intensities at the Earth and at V1 during this time period is remarkable
(0.921), after allowing for a ~0.9 year delay due to the solar wind propagation
time from the Earth to the outer heliosphere. To describe the intensity changes
and to predict the absolute intensities measured at all three locations we have
used a simple spherically symmetric (no drift) two-zone heliospheric transport
model with specific values for the diffusion coefficient in both the inner and
outer zones. The diffusion coefficient in the outer zone, assumed to be the
heliosheath from about 90 to 120 (130) AU, is determined to be ~5 times smaller
than that in the inner zone out to 90 AU. This means the Heliosheath acts much
like a diffusing barrier in this model. The absolute magnitude of the
intensities and the intensity changes at V1 and the Earth are described to
within a few percent by a diffusion coefficient that varies with time by a
factor ~4 in the inner zone and only a factor of ~1.5 in the outer zone over
the time period from 2004-2010. For V2 the observed intensities follow a curve
that is as much as 25% higher than the calculated intensities at the V2 radius
and at times the observed V2 intensities are equal to those at V1. At least
one-half of the difference between the calculated and observed intensities
between V1 and V2 can be explained if the heliosphere is squashed by ~10% in
distance (non-spherical) so that the HTS location is closer to the Sun in the
direction of V2 compared to V1.Comment: 13 Pages, 8 Figure
Alien plant invasions in South Africa: Driving forces and the human dimension
Invasive alien plants pose a substantial threat to the rich biodiversity of South Africa, and to the sustained delivery of a wide range of ecosystem services. Biological invasions are driven by human activities and mediated by culturally shaped values and ethics. This paper explores the human dimensions of alien plant invasions in South Africa. We consider four primary forces, those which directly influence the likelihood and rate of invasion — arrival of propagules; changes in disturbance regimes; changes in the availability of limiting factors; and fragmentation of the landscape — and the roles of 22 secondary driving forces in shaping the outcomes of the four primary driving forces. Human societies and their dynamics and activities are an integral part of each of the secondary driving forces. A map of the interactions between and among the primary and secondary driving forces shows how they are interlinked and influence each other — either positively or negatively, or switching between the two. There are two key points for intervention: prevention of the introduction of propagules of potentially invasive species and developing collaborative initiatives with enterprises that rely largely on alien species (for example, horticulture, agriculture and forestry, including community forestry) to minimize the introduction and use of potentially invasive species. An example of the first type of intervention would be to implement more effective inspection systems at international border and customs posts. This type of intervention can only be effective if those who are directly affected — whether businessmen, tourists or migrants — understand the requirement for these measures, and collaborate. The need to build public awareness of the critical importance of the human dimension of invasions emerges as a key theme from this analysis and is the basis for better-informed decisions, more effective control programmes and a reduction of further invasions
The Reaction Process A+A->O in Sinai Disorder
The single-species reaction-diffusion process is examined in the
presence of an uncorrelated, quenched random velocity field. Utilising a
field-theoretic approach, we find that in two dimensions and below the density
decay is altered from the case of purely diffusing reactants. In two-dimensions
the density amplitude is reduced in the presence of weak disorder, yielding the
interesting result that Sinai disorder can cause reactions to occur at an {\it
increased} rate. This is in contrast to the case of long-range correlated
disorder, where it was shown that the reaction becomes sub-diffusion limited.
However, when written in terms of the microscopic diffusion constant it is seen
that increasing the disorder has the effect of reducing the rate of the
reaction. Below two dimensions, the effect of Sinai disorder is much more
severe and the reaction is shown to become sub-diffusion limited. Although
there is no universal amplitude for the time-dependence of the density, it is
universal when expressed in terms of the disorder-averaged diffusion length.
The appropriate amplitude is calculated to one-loop order.Comment: 12 pages, 2 figure
Group actions on central simple algebras: a geometric approach
We study actions of linear algebraic groups on central simple algebras using
algebro-geometric techniques. Suppose an algebraic group G acts on a central
simple algebra A of degree n. We are interested in questions of the following
type: (a) Do the G-fixed elements form a central simple subalgebra of A of
degree n? (b) Does A have a G-invariant maximal subfield? (c) Does A have a
splitting field with a G-action, extending the G-action on the center of A?
Somewhat surprisingly, we find that under mild assumptions on A and the
actions, one can answer these questions by using techniques from birational
invariant theory (i.e., the study of group actions on algebraic varieties, up
to equivariant birational isomorphisms). In fact, group actions on central
simple algebras turn out to be related to some of the central problems in
birational invariant theory, such as the existence of sections, stabilizers in
general position, affine models, etc. In this paper we explain these
connections and explore them to give partial answers to questions (a)-(c).Comment: 33 pages. Final version, to appear in Journal of Algebra. Includes a
short new section on Brauer-Severi varietie
Carbon Nanotubes Synthesized in Channels of Alpo4-5 Single Crystals : First X-Ray Scattering Investigations
Following the synthesis of aligned single-wall carbon nanotubes in the
channels of AlPO4-5 zeolite single crystals, we present the first X-ray
diffraction and diffuse scattering results. They can be analysed in terms of a
partial filling of the zeolite channels by nanotubes with diameter around 4A.
The possible selection of only one type of nanotube during the synthesis, due
to the constraints imposed by the zeolite host, is discussed.Comment: to appear in Solid State Com
The solar wind disappearance event of 11 May 1999: source region evolution
Context. A recent, detailed study of the well-known solar wind disappearance
event of 11 May 1999 traced its origin to a coronal hole (CH) lying adjacent to
a large active region (AR), AR8525 in Carrington rotation 1949. The AR was
located at central meridian on 05 May 1999 when the flows responsible for this
event began. We examine the evolution of the AR-CH complex during 5-6 May 1999
to study the changes that apparently played a key role in causing this
disappearance event. Aims. To study the evolution of the solar source region of
the disappearance event of 11 May 1999. Methods. Using images from the Soft
X-ray Telescope (SXT), the Extreme-ultraviolet Imaging Telescope (EIT) and the
Michelson Doppler Imager (MDI) to examine the evolution of the CH and AR
complex at the source region of the disappearance event. Results. We find a
dynamic evolution taking place in the CH-AR boundary at the source region of
the disappearance event of 11 May 1999. This evolution, which is found to
reduce the area of the CH, is accompanied by the formation of new loops in EUV
images that are spatially and temporally correlated with emerging flux regions
as seen in MDI data. Conclusions. In the period leading up to the disappearance
event of 11 May 1999, our observations, during quiet solar conditions and in
the absence of CMEs, provide the first clear evidence for Sun-Earth connection
originating from an evolving AR-CH region located at central meridian. With the
exception of corotating interacting regions (CIR), these observations provide
the first link between the Sun and space weather effects at 1 AU, arising from
non-explosive solar events.Comment: The paper has recently been accepted in A&A letters and this version
is an 8 page article with 4 figure
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