11,520 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
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
Pressure balance at the magnetopause: Experimental studies
The pressure balance at the magnetopause is formed by magnetic field and
plasma in the magnetosheath, on one side, and inside the magnetosphere, on the
other side. In the approach of dipole earth's magnetic field configuration and
gas-dynamics solar wind flowing around the magnetosphere, the pressure balance
predicts that the magnetopause distance R depends on solar wind dynamic
pressure Pd as a power low R ~ Pd^alpha, where the exponent alpha=-1/6. In the
real magnetosphere the magnetic filed is contributed by additional sources:
Chapman-Ferraro current system, field-aligned currents, tail current, and
storm-time ring current. Net contribution of those sources depends on
particular magnetospheric region and varies with solar wind conditions and
geomagnetic activity. As a result, the parameters of pressure balance,
including power index alpha, depend on both the local position at the
magnetopause and geomagnetic activity. In addition, the pressure balance can be
affected by a non-linear transfer of the solar wind energy to the
magnetosheath, especially for quasi-radial regime of the subsolar bow shock
formation proper for the interplanetary magnetic field vector aligned with the
solar wind plasma flow.Comment: 8 pages, 2 figure
Exposure to benzene at work and the risk of leukemia: a systematic review and meta-analysis
Background
A substantial number of epidemiologic studies have provided estimates of the relation between exposure to benzene at work and the risk of leukemia, but the results have been heterogeneous. To bridge this gap in knowledge, we synthesized the existing epidemiologic evidence on the relation between occupational exposure to benzene and the risk of leukemia, including all types combined and the four main subgroups acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).
Methods
A systematic literature review was carried out using two databases 'Medline' and 'Embase' from 1950 through to July 2009. We selected articles which provided information that can be used to estimate the relation between benzene exposure and cancer risk (effect size).
Results
In total 15 studies were identified in the search, providing 16 effect estimates for the main analysis. The summary effect size for any leukemia from the fixed-effects model was 1.40 (95% CI, 1.23-1.57), but the study-specific estimates were strongly heterogeneous (I2 = 56.5%, Q stat = 34.47, p = 0.003). The random-effects model yielded a summary- effect size estimate of 1.72 (95% CI, 1.37-2.17). Effect estimates from 9 studies were based on cumulative exposures. In these studies the risk of leukemia increased with a dose-response pattern with a summary-effect estimate of 1.64 (95% CI, 1.13-2.39) for low (< 40 ppm-years), 1.90 (95% CI, 1.26-2.89) for medium (40-99.9 ppm-years), and 2.62 (95% CI, 1.57-4.39) for high exposure category (> 100 ppm-years). In a meta-regression, the trend was statistically significant (P = 0.015). Use of cumulative exposure eliminated heterogeneity. The risk of AML also increased from low (1.94, 95% CI, 0.95-3.95), medium (2.32, 95% CI, 0.91-5.94) to high exposure category (3.20, 95% CI, 1.09-9.45), but the trend was not statistically significant.
Conclusions
Our study provides consistent evidence that exposure to benzene at work increases the risk of leukemia with a dose-response pattern. There was some evidence of an increased risk of AML and CLL. The meta-analysis indicated a lack of association between benzene exposure and the risk of CML
Risk assessment, eradication, and biological control: global efforts to limit Australian acacia invasions
Aim? Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group. Location? Global. Methods? Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions. Results? Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long-lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success. Main conclusions? A greater emphasis on pro-active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on-going monitoring and management, and ensuring resources are in place for long-term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track-record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans-boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best-practice procedures can be developed. (Résumé d'auteur
Endogenous GABA controls oligodendrocyte lineage cell number, myelination, and CNS internode length
Adjusting the thickness and internodal length of the myelin sheath is a mechanism for tuning the conduction velocity of axons to match computational needs. Interactions between oligodendrocyte precursor cells (OPCs) and developing axons regulate the formation of myelin around axons. We now show, using organotypic cerebral cortex slices from mice expressing eGFP in Sox10-positive oligodendrocytes, that endogenously released GABA, acting on GABAA receptors, greatly reduces the number of oligodendrocyte lineage cells. The decrease in oligodendrocyte number correlates with a reduction in the amount of myelination but also an increase in internode length, a parameter previously thought to be set by the axon diameter or to be a property intrinsic to oligodendrocytes. Importantly, while TTX block of neuronal activity had no effect on oligodendrocyte lineage cell number when applied alone, it was able to completely abolish the effect of blocking GABAA receptors, suggesting that control of myelination by endogenous GABA may require a permissive factor to be released from axons. In contrast, block of AMPA/KA receptors had no effect on oligodendrocyte lineage cell number or myelination. These results imply that, during development, GABA can act as a local environmental cue to control myelination and thus influence the conduction velocity of action potentials within the CNS. GLIA 2017;65:309-321
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
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