8,201 research outputs found
Predicting the critical density of topological defects in O(N) scalar field theories
O(N) symmetric field theories describe many critical
phenomena in the laboratory and in the early Universe. Given N and ,
the dimension of space, these models exhibit topological defect classical
solutions that in some cases fully determine their critical behavior. For N=2,
D=3 it has been observed that the defect density is seemingly a universal
quantity at T_c. We prove this conjecture and show how to predict its value
based on the universal critical exponents of the field theory. Analogously, for
general N and D we predict the universal critical densities of domain walls and
monopoles, for which no detailed thermodynamic study exists. This procedure can
also be inverted, producing an algorithm for generating typical defect networks
at criticality, in contrast to the canonical procedure, which applies only in
the unphysical limit of infinite temperature.Comment: 4 pages, 3 figures, uses RevTex, typos in Eq.(11) and (14) correcte
Elective Laparoscopic Cholecistectomy in a Severe Hemophilia A Patient with Inhibitors to Factor VII
c-Src inhibition improves cardiovascular function but not remodeling or fibrosis in Ang II-induced hypertension
c-Src plays an important role in angiotensin II (Ang II) signaling. Whether this member of the Src family kinases is involved in the development of Ang II–induced hypertension and associated cardiovascular damage in vivo remains unknown. Here, we studied Ang II–infused (400 ng/kg/min) mice in which c-Src was partially deleted (c-Src+/−) and in wild-type (WT, c-Src+/+) mice treated with a c-Src inhibitor (CGP077675; 25 mg/kg/d). Ang II increased blood pressure and induced endothelial dysfunction in WT mice, responses that were ameliorated in c-Src+/− and CGP077675-treated mice. Vascular wall thickness and cross-sectional area were similarly increased by Ang II in WT and c-Src+/− mice. CGP077675 further increased cross-sectional area in hypertensive mice. Cardiac dysfunction (ejection fraction and fractional shortening) in Ang II–infused WT mice was normalized in c-Src+/− mice. Increased oxidative stress (plasma thiobarbituric acid–reactive substances, hydrogen peroxide, and vascular superoxide generation) in Ang II–infused WT mice was attenuated in c-Src–deficient and CGP077675-treated mice. Hyperactivation of vascular c-Src, ERK1/2 (extracellular signal–regulated kinase 1/2), and JNK (c-Jun N-terminal kinase) in hypertensive mice was normalized in CGP077675-treated and c-Src+/− mice. Vascular fibronectin was increased by Ang II in all groups and further augmented by CGP077675. Cardiac fibrosis and inflammation induced by Ang II were amplified in c-Src+/− and CGP-treated mice. Our data indicate that although c-Src downregulation attenuates development of hypertension, improves endothelial and cardiac function, reduces oxidative stress, and normalizes vascular signaling, it has little beneficial effect on fibrosis. These findings suggest a divergent role for c-Src in Ang II–dependent hypertension, where c-Src may be more important in regulating redox-sensitive cardiac and vascular function than fibrosis and remodeling
Detection and Quantification of Grass and Olea Airborne Pollen Allergens in Outdoor Air Samples and its Correlation with Pollen Counts
Detection and Quantification of Grass and Olea Airborne Pollen Allergens in Outdoor Air Samples and its Correlation with Pollen Counts
R Ferro1*, R Ribeiro1*, MR Martins1,2, AT Caldeira1,3, E Caeiro6, CM Antunes1,5
& R Brandão2,4 and the HIALINE working group7
1Dep. of Chemistry, University of Evora, Portugal;
2Mediterranean Inst. Crop and Environment Sciences, Univ.Evora, Portugal;
3Centro QuÃmica, University of Évora, Portugal;
4Dep. Biology, University of Evora;
5Center for NeuroSciences and Cell Biology-University of Coimbra, Portugal;
6Soc.Portuguesa Alergol.Imunologia ClÃnica , Portugal
7 M. Thibaudon, France, M. Smith, United Kingdom, C. Galan, Spain R. Albertini, Italy, L. Grewling, Poland, G. Reese, Germany, A. Rantio-Lehtimäki, Finland, S. Jäger and U. Berger, Austria, M. Sofiev, Finland, I. Sauliene, Lithuania, L. Cecchi, Italy
Presenting author: [email protected] tel: +351 266760889
Introduction: Allergic respiratory diseases broken out after an exposure to airborne pollen, as asthma and allergic rhinitis, are deeply increasing and they represent one of the major public health problems nowadays, affecting about 40% of European population. In Portugal, grass and Olea europaea pollen are certainly one of the main sources of athmospheric aeroallergens and as such, one of the main causes of respiratory allergy.
For these reasons, it is useful the development of new strategies for prevention and treatment of these pathologies. The execution of aerobiological analysis including pollen calendars and/or immunoassays for the detection and quantification of allergens which could forecast the allergenic potential of the athmosphere are quite relevant since they would contribute to develop prevention measures of allergic respiratory diseases. The aim of this study was to evaluate the putative correlation between the concentration of some of the major allergens of and with their pollen counts.
Methodology: On a meteorological platform at the town center of Evora (south Portugal), ambient air was sampled at 800L/min with a Chemvol high-volume cascade impactor equipped with stages PM>10µm, 10 µm>PM>2.5µm. The polyurethane impacting substrate was extracted with 0.1M NH4HCO3, pH8.1, supplemented with 0.1% BSA. The major pollen allergens from grass Phleum p 5 and olive Ole e 1 were determined with allergen specific ELISA´s. Airborne pollen of and Olea europaea simultaneously monitored with a Burkard Seven Day Recording Volumetric Spore Trap* , between the 30th of April and the 8th of July of 2009. Both samplers were placed side-by-side with air input at the same level.
Results: During the pollen season of 2009, high values of grass pollen were recorded between May 2th and June 1 th. It was also observed that the air content of Phl p5 or Ole e1 aeroallergens were directly correlated with airborne pollen counts of Poaceae and Oleaceae, respectively.
Conclusions: These results suggest that the directly quantification of aeroallergens may contribute, together with pollen counts of air samples, to define the allergic risk with higher precision.
Acknowledgments: This study is integrated in the european project HIALINE (Executive Agency for Health and Consumers under grant agreement No 2008 11 07
Environmental risk evaluation of potential toxic elements in stream sediments – Monfortinho area (Central Portugal)
Os elementos potencialmente tóxicos (EPT) em sedimentos de corrente constituem uma importante ferramenta na avaliação do risco ambiental na influência de depósitos minerais. A região de Monfortinho está localizada na bacia hidrográfica do rio Erges, que faz fronteira com Espanha. Desde a época romana, que se conhecem evidências da exploração de ouro sedimentar nesta região do paÃs, a qual tem vindo a desaparecer ao longo do tempo. Na avaliação da distribuição espacial de EPT selecionados – As, B, Ba, Cd, Cu, Fe, Ni, Pb, V e Zn - foram analisadas 217 amostras de sedimentos de corrente. Os sedimentos de corrente mostram uma elevada variabilidade na concentração dos EPT, podendo concluir-se que os valores mais elevados se relacionam com as mineralizações de Au na região de Monfortinho, bem como, com as de Sn-W que ocorrem nas proximidades. A maioria dos EPT apresenta um fator de contaminação moderado, embora para o Ba, Cr e B este seja elevado a muito elevado; o que se reflete num grau de contaminação moderado a elevado para a área de estudo. Na influência dos vários EPT, a maioria da área mostra um Ãndice de resposta à toxicidade baixo, embora em 5% das amostras este seja moderado.Potentially toxic elements (PTE) of stream sediments are an important tool in environmental risk assessment associated with
mineralized deposits. εonfortinho is in the watershed of the Erges river, a transboundary river with Spain. Since Roman period,
there is evidence of sedimentary gold exploitation in this region, which has ceased over time. To define a spatial distribution of
selected PTE - As, B, Ba, Cd, Cu, Fe, Ni, Pb, V and Zn - β17 samples of stream sediments were analysed. Stream sediments
show a high PTE contents variability, suggesting that the highest values are related to the Au mineralization in εonfortinho, as
well as the Sn-→ mineralization’s around the study area. Almost stream sediments show a moderate PTE contamination factor,
although for Ba, Cr and B has a very high contamination; which is reflected in a moderate to high degree of contamination in the
area. All the PTE contribution indicate a low toxic response index for the area, although for 5% of stream sediments indicate a
moderate associated toxicity.Os autores agradecem ao δNEG (atual
representante dos Serviços Geológicos de
Portugal) pela cedência dos dados. Este
trabalho foi desenvolvido no âmbito do ICT
– Universidade do εinho (Braga).info:eu-repo/semantics/publishedVersio
The role of point-like topological excitations at criticality: from vortices to global monopoles
We determine the detailed thermodynamic behavior of vortices in the O(2)
scalar model in 2D and of global monopoles in the O(3) model in 3D. We
construct new numerical techniques, based on cluster decomposition algorithms,
to analyze the point defect configurations. We find that these criteria produce
results for the Kosterlitz-Thouless temperature in agreement with a topological
transition between a polarizable insulator and a conductor, at which free
topological charges appear in the system. For global monopoles we find no pair
unbinding transition. Instead a transition to a dense state where pairs are no
longer distinguishable occurs at T<Tc, without leading to long range disorder.
We produce both extensive numerical evidence of this behavior as well as a
semi-analytic treatment of the partition function for defects. General
expectations for N=D>3 are drawn, based on the observed behavior.Comment: 14 pages, REVTEX, 13 eps figure
Numerical simulation of stochastic vortex tangles
We present the results of simulation of the chaotic dynamics of quantized
vortices in the bulk of superfluid He II.
Evolution of vortex lines is calculated on the base of the Biot-Savart law.
The dissipative effects appeared from the interaction with the normal
component, or/and from relaxation of the order parameter are taken into
account. Chaotic dynamics appears in the system via a random forcing, e.i. we
use the Langevin approach to the problem. In the present paper we require the
correlator of the random force to satisfy the fluctuation-disspation relation,
which implies that thermodynamic equilibrium should be reached. In the paper we
describe the numerical methods for integration of stochastic differential
equation (including a new algorithm for reconnection processes), and we present
the results of calculation of some characteristics of a vortex tangle such as
the total length, distribution of loops in the space of their length, and the
energy spectrum.Comment: 8 pages, 5 figure
Crystal Structure Generation with Autoregressive Large Language Modeling
The generation of plausible crystal structures is often an important step in
the computational prediction of crystal structures from composition. Here, we
introduce a methodology for crystal structure generation involving
autoregressive large language modeling of the Crystallographic Information File
(CIF) format. Our model, CrystaLLM, is trained on a comprehensive dataset of
millions of CIF files, and is capable of reliably generating correct CIF syntax
and plausible crystal structures for many classes of inorganic compounds.
Moreover, we provide general and open access to the model by deploying it as a
web application, available to anyone over the internet. Our results indicate
that the model promises to be a reliable and efficient tool for both
crystallography and materials informatics
Predicting Thermoelectric Transport Properties from Composition with Attention-based Deep Learning
Thermoelectric materials can be used to construct devices which recycle waste
heat into electricity. However, the best known thermoelectrics are based on
rare, expensive or even toxic elements, which limits their widespread adoption.
To enable deployment on global scales, new classes of effective thermoelectrics
are thus required. models of transport properties can help
in the design of new thermoelectrics, but they are still too computationally
expensive to be solely relied upon for high-throughput screening in the vast
chemical space of all possible candidates. Here, we use models constructed with
modern machine learning techniques to scan very large areas of inorganic
materials space for novel thermoelectrics, using composition as an input. We
employ an attention-based deep learning model, trained on data derived from
calculations, to predict a material's Seebeck coefficient,
electrical conductivity, and power factor over a range of temperatures and
- or -type doping levels, with surprisingly good
performance given the simplicity of the input, and with significantly lower
computational cost. The results of applying the model to a space of known and
hypothetical binary and ternary selenides reveal several materials that may
represent promising thermoelectrics. Our study establishes a protocol for
composition-based prediction of thermoelectric behaviour that can be easily
enhanced as more accurate theoretical or experimental databases become
available
Aerosol and precipitation chemistry in a remote site in Central Amazonia: the role of biogenic contribution
International audienceA long-term (2?3 years) measurement of aerosol and precipitation chemistry was carried out in a remote site in Central Amazonia, Balbina, (1°55' S, 59°29' W, 174 m above sea level), about 200 km north of Manaus city. Aerosols were sampled using stacked filter units (SFU), which separate fine (d<2.5 ?m) and coarse mode (2.5 ?
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