220 research outputs found
Photonic measurements of the longitudinal expansion dynamics in Heavy-Ion collisions
Due to the smallness of the electromagnetic coupling, photons escape from the
hot and dense matter created in an heavy-ion collision at all times, in
contrast to hadrons which are predominantly emitted in the final freeze-out
phase of the evolving system. Thus, the thermal photon yield carries an imprint
from the early evolution. We suggest how this fact can be used to gain
information about where between the two limiting cases of Bjorken
(boost-invariant expansion) and Landau (complete initial stopping and
re-expansion) hydrodynamics the actual evolution can be found. We argue that
both the rapidity dependence of the photon yield and photonic HBT radii are
capable of answering this question.Comment: 10 pages, 3 figure
Graphene Oxidation: Thickness Dependent Etching and Strong Chemical Doping
Patterned graphene shows substantial potential for applications in future
molecular-scale integrated electronics. Environmental effects are a critical
issue in a single layer material where every atom is on the surface. Especially
intriguing is the variety of rich chemical interactions shown by molecular
oxygen with aromatic molecules. We find that O2 etching kinetics vary strongly
with the number of graphene layers in the sample. Three-layer-thick samples
show etching similar to bulk natural graphite. Single-layer graphene reacts
faster and shows random etch pits in contrast to natural graphite where
nucleation occurs at point defects. In addition, basal plane oxygen species
strongly hole dope graphene, with a Fermi level shift of ~0.5 eV. These oxygen
species partially desorb in an Ar gas flow, or under irradiation by far UV
light, and readsorb again in an O2 atmosphere at room temperature. This
strongly doped graphene is very different than graphene oxide made by mineral
acid attack.Comment: 15 pages, 5 figure
Cytokine alterations in first-episode schizophrenia patients before and after antipsychotic treatment
Schizophrenia has been associated with central nervous system and peripheral immune system imbalances. However, most studies have not yielded conclusive results due to limitations such as small sample size, dissimilarities in the clinical status of patients and the high variability of cytokine levels within the normal human population. Here, we have attempted to account for these limitations by carrying out standardised multiplex immunoassay analyses of 9 cytokines in serum from 180 antipsychotic-naïve first-episode schizophrenia patients and 350 matched controls across 5 clinical cohorts. All subjects were matched for potential confounding factors including age, gender, smoking and body mass index. We found that the levels of interleukin (IL)-1RA, IL-10 and IL-15 were increased significantly in patients across the cohorts. We also found that the levels of IL-1RA and IL-10 were decreased in 32 patients who had been followed up and treated for 6. weeks with atypical antipsychotics. Interestingly, we found that the changes in IL-10 levels were significantly correlated with the improvements in negative, general and total symptom scores. These results indicate that mixed pro- and anti-inflammatory responses may be altered in first onset patients, suggesting a role in the aetiology of schizophrenia. The finding that only the anti-inflammatory cytokine IL-10 responded to treatment in parallel with symptom improvement suggests that this could be used as a potential treatment response biomarker in future studies of schizophrenia
COST 296 scientific results designed for operational use
The main objective of the COST 296 Action «Mitigation of Ionospheric Effects on Radio Systems» is the establishment/
improvement of ionospheric services by coordinating the development of specific algorithms, models, and tools capable of operating in a near-real-time mode.
Key elements of these activities are contributions related to monitoring, modelling, and imaging of customer-relevant
ionospheric quantities. COST stimulates, coordinates, and supports Europe’s goals of development and global cooperation by providing high quality information and knowledge of ionospheric and plasmaspheric conditions enabling high quality and reliable operation of radio systems.
It also provides a platform for sharing such tools as algorithms or models, and for the joint development of advanced
technologies. It takes advantage of many national and European service initiatives, for example DIAS
(http://dias.space.noa.gr), SWACI (http://w3swaci.dlr.de), ESWUA (http://www.eswua.ingv.it/ingv), RWC-Warsaw
(http://www.cbk.waw.pl/rwc), the COST Prompt Ionospheric Database http://www.wdc.rl.ac.uk/cgibin/
digisondes/cost_database.pl, http://www.izmiran.ru/services, and others.
Existing national capabilities are taken into account to develop synergies and avoid duplication. The enhancement of environment monitoring networks and associated instrumentation yields mutual advantages for European and regional services specialized for local user needs.
It structurally increases the integration of limited-area services, and generates a platform employing the same approach to each task differing mostly in input and output data. In doing so it also provides a complementary description of the environmental state within issued information, as well as providing a platform for interaction among local end users, who define what kind of information they need, for system providers, who finalize the
tools necessary to obtain required information, and for local service providers, who do the actual processing of
data, tailoring it to specific users’ needs. Such an initiative creates a unique opportunity for small national services
to consolidate their product design so that is no longer limited to their own activity, but can serve the wider European services.
The development and improvement of techniques for mitigating ionospheric effects on radio systems by the
COST 296 Action prepared those services that implemented the new design techniques for the newly announced EU and ESA policy-Space Situation Awareness (SSA). COST 296 developments applied to nowcasting and forecasting services are an essential input to the Operational SSA Ionosphere
Near-Earth space plasma modelling and forecasting
In the frame of the European COST 296 project (Mitigation of Ionospheric Effects on Radio Systems, MIERS)in the Working Package 1.3, new ionospheric models, prediction and forecasting methods and programs as well as ionospheric imaging techniques have been developed. They include (i) topside ionosphere and meso-scale irregularity models, (ii) improved forecasting methods for real time forecasting and for prediction of foF2,
M(3000)F2, MUF and TECs, including the use of new techniques such as Neurofuzzy, Nearest Neighbour, Cascade Modelling and Genetic Programming and (iii) improved dynamic high latitude ionosphere models through tomographic imaging and model validation. The success of the prediction algorithms and their improvement over
existing methods has been demonstrated by comparing predictions with later real data. The collaboration between different European partners (including interchange of data) has played a significant part in the development and validation of these new prediction and forecasting methods, programs and algorithms which can be applied to a variety of practical applications leading to improved mitigation of ionosphereic and space weather effects.Published255-2713.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeJCR Journalope
Near-Earth space plasma modelling and forecasting
In the frame of the European COST 296 project (Mitigation of Ionospheric Effects on Radio Systems, MIERS)in the Working Package 1.3, new ionospheric models, prediction and forecasting methods and programs as well as ionospheric imaging techniques have been developed. They include (i) topside ionosphere and meso-scale irregularity models, (ii) improved forecasting methods for real time forecasting and for prediction of foF2,
M(3000)F2, MUF and TECs, including the use of new techniques such as Neurofuzzy, Nearest Neighbour, Cascade Modelling and Genetic Programming and (iii) improved dynamic high latitude ionosphere models through tomographic imaging and model validation. The success of the prediction algorithms and their improvement over
existing methods has been demonstrated by comparing predictions with later real data. The collaboration between different European partners (including interchange of data) has played a significant part in the development and validation of these new prediction and forecasting methods, programs and algorithms which can be applied to a variety of practical applications leading to improved mitigation of ionosphereic and space weather effects
Resonances and fluctuations of strange particle in 200 GeV Au-Au collisions
We perform an analysis of preliminary data on strange particles yields and
fluctuations within the Statistical hadronization model. We begin by describing
the theoretical disagreements between different statistical models currently on
the market. We then show how the simultaneous analysis of yields and
fluctuations can be used to differentiate between the different models, and
determine if one of them can be connected to underlying physics. We perform a
study on a RHIC 200 GeV data sample that includes stable particles, resonances,
and the event-by-event fluctuation of the ratio. We show that the
equilibrium statistical model can not describe the fluctuation, unless an
unrealistically small volume is assumed. Such small volume then makes it
impossible to describe the total particle multiplicity. The non-equilibrium
model,on the other hand, describes both the fluctuation and yields
acceptably due to the extra boost to the fluctuation provided by the high
pion chemical potential. and abundance is described
within error bars, but the is under-predicted to 1.5 standard
deviations. We suggest further measurements that have the potential to test the
non-equilibrium model, as well as gauge the effect of re-interactions between
hadronization and freeze-out.Comment: References added, equations corrected. As accepted for publication by
Journal of Physics
Space-time analysis of reaction at RHIC
Space-time information about the Au-Au collisions produced at RHIC are key
tools to understand the evolution of the system and especially assess the
presence of collective behaviors. Using a parameterization of the system's
final state relying on collective expansion, we show that pion source radii can
be tied together with transverse mass spectra and elliptic flow within the same
framework. The consistency between these different measures provide a solid
ground to understand the characteristics of collective flow and especially the
possible peculiar behavior of particles such as Xi, Omega or phi. The validity
of the short time scales that are extracted from fits to the pion source size
is also addressed. The wealth of new data that will soon be available from
Au-Au collisions at sqrt{s_{NN}} = 200 GeV, will provide a stringet test of the
space-time analysis framework developped in these proceedings.Comment: Invited talk given at the SQM2003 conference (March 2003), to be
published in Journal of Physics G. 10 pages, 3 figure
Climate change promotes parasitism in a coral symbiosis.
Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals' sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodinium phylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change
- …