2,434 research outputs found
Time-domain numerical simulations of multiple scattering to extract elastic effective wavenumbers
Elastic wave propagation is studied in a heterogeneous 2-D medium consisting
of an elastic matrix containing randomly distributed circular elastic
inclusions. The aim of this study is to determine the effective wavenumbers
when the incident wavelength is similar to the radius of the inclusions. A
purely numerical methodology is presented, with which the limitations usually
associated with low scatterer concentrations can be avoided. The elastodynamic
equations are integrated by a fourth-order time-domain numerical scheme. An
immersed interface method is used to accurately discretize the interfaces on a
Cartesian grid. The effective field is extracted from the simulated data, and
signal-processing tools are used to obtain the complex effective wavenumbers.
The numerical reference solution thus-obtained can be used to check the
validity of multiple scattering analytical models. The method is applied to the
case of concrete. A parametric study is performed on longitudinal and
transverse incident plane waves at various scatterers concentrations. The phase
velocities and attenuations determined numerically are compared with
predictions obtained with multiple scattering models, such as the Independent
Scattering Approximation model, the Waterman-Truell model, and the more recent
Conoir-Norris model.Comment: Waves in Random and Complex Media (2012) XX
Impact of the 2009 influenza A(H1N1) pandemic wave on the pattern of hibernal respiratory virus epidemics, France, 2009.
International audienceThis short report based on clinical surveillance and laboratory data describes the circulation of rhinoviruses, influenza viruses and respiratory syncytial viruses (RSV) in France during the 2009-10 season compared with the previous winter season. The delayed circulation of RSV observed in 2009-10 compared with 2008-09 suggests that the early circulation of the 2009 pandemic influenza A(H1N1) viruses had an impact on the RSV epidemic
Spontaneous regression of metastatic renal cell carcinoma: case report
Spontaneous regression of metastatic renal cell carcinoma is rarely observed. A case of suspected spontaneous regression of pulmonary metastases following nephrectomy for histologically proven renal cell carcinoma without systemic treatment is presented along with a brief review of the literature
B1 Was the Ancestor B Chromosome Variant in the Western Mediterranean Area in the Grasshopper Eyprepocnemis plorans.
We analyzed the distribution of 2 repetitive DNAs, i.e. ribosomal
DNA (rDNA) and a satellite DNA (satDNA), on the B chromosomes
found in 17 natural populations of the grasshopper Eyprepocnemis
plorans plorans sampled around the western
Mediterranean region, including the Iberian Peninsula, Balearic
Islands, Sicily, and Tunisia. Based on the amount of these
repetitive DNAs, 4 types of B variants were found: B 1 , showing
an equal or higher amount of rDNA than satDNA, and 3 other
variants, B 2 , B 24 and B 5 , bearing a higher amount of satDNA
than rDNA. The variants B 1 and B 2 varied in size among populations:
B 1 was about half the size of the X chromosome in Balearic
Islands, but two-thirds of the X in Iberian populations at
Alicante, Murcia and Albacete provinces. Likewise, B 2 was
about one-third the size of the X chromosome in populations
from the Granada province but half the size of the X in the
populations collected at Málaga province. The widespread
geographical distribution of the B 1 variant makes it the best
candidate for being the ancestor B chromosome in the whole
western Mediterranean region
Adaptive memory: Stereotype activation is not enough
Studies have shown that survival processing leads to superior memorability. The aim of the present study was to examine whether this survival recall advantage might result from stereotype activation. To test this hypothesis, we conducted a pilot study and two experiments in which participants were primed with stereotypes (Experiment 1, professor and elderly person; Experiment 2, survival-stereotype). In Experiment 1, 120 undergraduates were randomly assigned to a survival, professor stereotype, elderly person stereotype, or moving scenario and rated words for their relevance to the imagined scenario. In Experiment 2, 75 undergraduates were given a survival, survival-stereotype (based on our pilot study), or moving scenario. Both experiments showed that survival processing leads to a greater recall advantage over the stereotype groups and control group. These data indicate that the mere activation of stereotypes cannot explain the survival recall advantage
Esterilização tubária histeroscópica com Essure ® : um estudo observacional de 7 anos
Introduction: Hysteroscopic sterilization with the Essure® device is a method of contraception considered safe and
effective already applied in more than 200,000 women. This study aims to evaluate the efficacy of this method of contraception and the adverse events associated with the placement of Essure®, including pain during the procedure and postprocedure complications.
Material and methods: We performed a retrospective observational study with inclusion of all the women submitted to
Essure® placement in a large urban hospital in Portugal, from January 2008 to December 2015 (7 years). The variables
age, parity, duration and intercurrences of the procedure, follow-up exams and final outcome were evaluated. The statistical analysis was performed with STATA 12.1.
Results: Of the 118 women only 100 finished the procedure with 16.9% reporting moderate or severe pain. Although less
than 3 intrauterine rings were found in 8.5% of cases, the success rate was 92%. The complications described were tubal
perforation (0.8%), pregnancy (1 case) and incorrect positioning of the implants (3%).
Discussion/Conclusion: The success rate of the procedure was very close to that described in the literature with a low incidence of complications. That advantages make it an idea method for women with high surgical risk and multiple co-morbiditiesinfo:eu-repo/semantics/publishedVersio
Entanglement Dynamics after a Quench in Ising Field Theory: A Branch Point Twist Field Approach
We extend the branch point twist field approach for the calculation of entanglement entropies to time-dependent problems in 1+1-dimensional massive quantum field theories. We focus on the simplest example: a mass quench in the Ising field theory from initial mass m0 to final mass m. The main analytical results are obtained from a perturbative expansion of the twist field one-point function in the post-quench quasi-particle basis. The expected linear growth of the Rényi entropies at large times mt ≫ 1 emerges from a perturbative calculation at second order. We also show that the Rényi and von Neumann entropies, in infinite volume, contain subleading oscillatory contributions of frequency 2m and amplitude proportional to (mt)−3/2. The oscillatory terms are correctly predicted by an alternative perturbation series, in the pre-quench quasi-particle basis, which we also discuss. A comparison to lattice numerical calculations carried out on an Ising chain in the scaling limit shows very good agreement with the quantum field theory predictions. We also find evidence of clustering of twist field correlators which implies that the entanglement entropies are proportional to the number of subsystem boundary points
Areas of natural occurrence of melipona scutellaris Latreille, 1811(Hymenoptera: Apidae) in the state of Bahia, Brazil.
The bee Melipona scutellaris is considered the reared meliponine species with the largest distribution in the North and Northeast regions of Brazil, with records from the state of Rio Grande do Norte down to the state of Bahia. Considering the importance of this species in the generation of income for family agriculture and in the preservation of areas with natural vegetation, this study aimed at providing knowledge on the distribution of natural colonies of M. scutellaris in the state of Bahia. Literature information, interviews with stinglessbee beekeepers, and expeditions were conducted to confirm the natural occurrence of the species. A total of 102 municipalities showed records for M. scutellaris, whose occurrence was observed in areas ranging from sea level up to 1,200-meter height. The occurrence of this species in the state of Bahia is considered to be restricted to municipalities on the coastal area and the Chapada Diamantina with its rainforests. Geographic coordinates, elevation, climate and vegetation data were obtained, which allowed a map to be prepared for the area of occurrence in order to support conservation and management policies for the species
Quantitative study of hydration of C3S and C2S by thermal analysis. Evolution and composition of C-S-H gels formed
This research is part of a European project (namely, CODICE project), main objective of which is modelling, at a multi-scale, the evolution of the mechanical performance of non-degraded and degraded cementitious matrices. For that, a series of experiments were planned with pure synthetic tri-calcium silicate (C3S) and bi-calcium silicate (C2S) (main components of the Portland cement clinker) to obtain different calcium–silicate–hydrate (C–S–H) gel structures during their hydration. The characterization of those C–S–H gels and matrices will provide experimental parameters for the validation of the multi-scale modelling scheme proposed. In this article, a quantitative method, based on thermal analyses, has been used for the determination of the chemical composition of the C–S–H gel together with the degree of hydration and quantitative evolution of all the components of the pastes. Besides, the microstructure and type of silicate tetrahedron and mean chain length (MCL) were studied by scanning electron microscopy (SEM) and 29Si magic-angle-spinning (MAS) NMR, respectively. The main results showed that the chemical compositions for the C–S–H gels have a CaO/SiO2 M ratio almost constant of 1.7 for both C3S and C2S compounds. Small differences were found in the gel water content: the H2O/SiO2 M ratio ranged from 2.9 ± 0.2 to 2.6 ± 0.2 for the C3S (decrease) and from 2.4 ± 0.2 to 3.2 ± 0.2 for the C2S (increase). The MCL values of the C–S–H gels, determined from 29Si MAS NMR, were 3.5 and 4 silicate tetrahedron, for the hydrated C3S and C2S, respectively, remaining almost constant at all hydration periods
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