572 research outputs found
Angra Neutrino Project: status and plans
We present the status and plans of the Angra Project, a new nuclear reactor
neutrino oscillation experiment, proposed to be built in Brazil at the Angra
dos Reis nuclear reactor complex. This experiment is aimed to measure theta_13,
the last unknown of the three neutrino mixing angles. Combining a high
luminosity design, very low background from cosmic rays and careful control of
systematic errors at the 1% level, we propose a high sensitivity multi-detector
experiment, able to reach a sensitivity to antineutrino disappearance down to
sin^2(2*theta_13) = 0.006 in a three years running period, improving present
limits constrained by the CHOOZ experiment by more than an order of magnitude.Comment: 2 pages, 1 figure, talk presented by J.C. Anjos ([email protected]) at
NuFact05, 21-26 June 2005, Frascati, Ital
Towards a toolkit for the assessment and monitoring of musculoskeletal ageing
The complexities and heterogeneity of the ageing process have slowed the development of consensus on appropriate biomarkers of healthy ageing. The MRC-Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing (CIMA) is a collaboration between researchers and clinicians at the Universities of Liverpool, Sheffield and Newcastle. One of CIMA's objectives is to 'Identify and share optimal techniques and approaches to monitor age-related changes in all musculoskeletal tissues, and to provide an integrated assessment of musculoskeletal function', i.e. to develop a toolkit for assessing musculoskeletal ageing. This toolkit is envisaged as an instrument that can be used to characterise and quantify musculoskeletal function during 'normal' ageing, lend itself to use in large-scale, internationally important cohorts, and provide a set of biomarker outcome measures for epidemiological and intervention studies designed to enhance healthy musculoskeletal ageing. Such potential biomarkers include: biochemical measurements in biofluids or tissue samples, in vivo measurements of body composition, imaging of structural and physical properties, and functional tests. The CIMA Toolkit Working Group assessed candidate biomarkers of musculoskeletal ageing under these four headings, detailed their biological bases, strengths and limitations, and made practical recommendations for their use. In addition, the CIMA Toolkit Working Group identified gaps in the evidence base and suggested priorities for further research on biomarkers of musculoskeletal ageing
Experimental demonstration of time dilatation and space contraction of cosmic-ray muons
We present a modern physics experiment using a cosmic ray muons telescope. The telescope assembly with plastic scintillators and modular electronics is described. The classical mechanics and the special theory of relativity are used to calculate the intensity of múons on the Earth's surface. The vertical intensity measured at Campinas was (141 ± 1) muons/(m².s.sr) and can be explained with the muons lifetime dilatation or length contraction in the muon rest frame.Apresentamos uma atividade experimental de física moderna realizada com um telescópio de múons da radiação cósmica. A montagem do telescópio, feita com cintiladores plásticos, e a eletrônica utilizada são descritas. Utilizando a mecânica clássica e a teoria especial da relatividade, calculamos a intensidade esperada para os múons na superfície da Terra. Medimos uma intensidade vertical de (141 ± 1) múons/(m².s.sr) em Campinas e demonstramos que somente com a dilatação do tempo de vida dos múons, ou a contração do espaço no referencial do múon, podemos explicar os resultados experimentais.585591Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Guidelines for community-based injury surveillance in rugby union
Objectives
The vast majority of rugby union (‘rugby’) participants are community-based players; however, the majority of injury surveillance studies reported relate to the elite, professional game. A potential reason for this dearth of studies could be the perceived difficulty of using the consensus statement for injury recording at the community level. The aim of this study was to identify areas where the consensus statement could be adapted for easier and more appropriate implementation within the community setting.
Design
Round-table discussion
Methods
All community-based injury surveillance issues were discussed during a 2-day facilitated round-table meeting, by an 11-person working group consisting of researchers currently active in rugby-related injury surveillance, sports medicine and sports science issues. The outcomes from the meeting were summarised in a draft guidance document that was then subjected to an extensive iterative review prior to producing methodological recommendations.
Results
Each aspect of the rugby-specific consensus statement was reviewed to determine whether it was feasible to implement the standards required in the context of non-elite rugby and the resources available within in a community setting. Final recommendations are presented within a community-based injury report form.
Conclusions
It is recommended that whenever possible the rugby-specific consensus statement for injury surveillance studies be used: this paper presents an adapted report form that can be used to record injury surveillance information in community rugby if suitable medical support is not available
Immobilisation of chromium in magnesium carbonate minerals
Hexavalent chromium (Cr6+) is a toxic carcinogenic pollutant that might be released by the mining and processing of ultramafic rocks and nickel laterites and which requires permanent removal from the contaminated biosphere. Ultramafic material can also serve as a feedstock for the sequestration of CO2 resulting from the growth of new minerals, raising the intriguing proposition of integrated sequestration of both pollutants, CO2 and chromium, into magnesium carbonates. Such a synergistic process downstream of ore recovery and mineral processing could be an elegant proposition for more sustainable utilisation and management of the Earth's resources. We have therefore carried out an experimental and microanalytical study to investigate potentially suitable carbonate minerals. Uptake of chromium in carbonate phases was determined, followed by identification of the crystalline phases and characterisation of the local structural environment around the incorporated chromium centres. The results suggest that neither nesquehonite nor hydromagnesite have the structural capacity to incorporate Cr6+ or Cr3+ significantly at room temperature. We therefore propose that further research into this technology should focus on laboratory assessments of other phases, such as layered double hyroxides, that have a natural structural capacity to uptake both chromium and CO2
Hexatic-Herringbone Coupling at the Hexatic Transition in Smectic Liquid Crystals: 4- Renormalization Group Calculations Revisited
Simple symmetry considerations would suggest that the transition from the
smectic-A phase to the long-range bond orientationally ordered hexatic
smectic-B phase should belong to the XY universality class. However, a number
of experimental studies have constantly reported over the past twenty years
"novel" critical behavior with non-XY critical exponents for this transition.
Bruinsma and Aeppli argued in Physical Review Letters {\bf 48}, 1625 (1982),
using a renormalization-group calculation, that short-range
molecular herringbone correlations coupled to the hexatic ordering drive this
transition first order via thermal fluctuations, and that the critical behavior
observed in real systems is controlled by a `nearby' tricritical point. We have
revisited the model of Bruinsma and Aeppli and present here the results of our
study. We have found two nontrivial strongly-coupled herringbone-hexatic fixed
points apparently missed by those authors. Yet, those two new nontrivial
fixed-points are unstable, and we obtain the same final conclusion as the one
reached by Bruinsma and Aeppli, namely that of a fluctuation-driven first order
transition. We also discuss the effect of local two-fold distortion of the bond
order as a possible missing order parameter in the Hamiltonian.Comment: 1 B/W eps figure included. Submitted to Physical Review E. Contact:
[email protected]
A global perspective on collision and non-collision match characteristics in male rugby union: Comparisons by age and playing standard
This study quantified and compared the collision and non-collision match characteristics across age categories (i.e. U12, U14, U16, U18, Senior) for both amateur and elite playing standards from Tier 1 rugby union nations (i.e. England, South Africa, New Zealand). Two-hundred and one male matches (5911 min ball-in-play) were coded using computerised notational analysis, including 193,708 match characteristics (e.g. 83,688 collisions, 33,052 tackles, 13,299 rucks, 1006 mauls, 2681 scrums, 2923 lineouts, 44,879 passes, 5568 kicks). Generalised linear mixed models with post-hoc comparisons and cluster analysis compared the match characteristics by age category and playing standard. Overall significant differences (p < 0.001) between age category and playing standard were found for the frequency of match characteristics, and tackle and ruck activity. The frequency of characteristics increased with age category and playing standard except for scrums and tries that were the lowest at the senior level. For the tackle, the percentage of successful tackles, frequency of active shoulder, sequential and simultaneous tackles increased with age and playing standard. For ruck activity, the number of attackers and defenders were lower in U18 and senior than younger age categories. Cluster analysis demonstrated clear differences in all and collision match characteristics and activity by age category and playing standard. These findings provide the most comprehensive quantification and comparison of collision and non-collision activity in rugby union demonstrating increased frequency and type of collision activity with increasing age and playing standard. These findings have implications for policy to ensure the safe development of rugby union players throughout the world.</p
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Magnetic Field Generation in Stars
Enormous progress has been made on observing stellar magnetism in stars from
the main sequence through to compact objects. Recent data have thrown into
sharper relief the vexed question of the origin of stellar magnetic fields,
which remains one of the main unanswered questions in astrophysics. In this
chapter we review recent work in this area of research. In particular, we look
at the fossil field hypothesis which links magnetism in compact stars to
magnetism in main sequence and pre-main sequence stars and we consider why its
feasibility has now been questioned particularly in the context of highly
magnetic white dwarfs. We also review the fossil versus dynamo debate in the
context of neutron stars and the roles played by key physical processes such as
buoyancy, helicity, and superfluid turbulence,in the generation and stability
of neutron star fields.
Independent information on the internal magnetic field of neutron stars will
come from future gravitational wave detections. Thus we maybe at the dawn of a
new era of exciting discoveries in compact star magnetism driven by the opening
of a new, non-electromagnetic observational window.
We also review recent advances in the theory and computation of
magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo
theory. These advances offer insight into the action of stellar dynamos as well
as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field
generation in stars to appear in Space Science Reviews, Springe
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
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