39 research outputs found

    A comparison of Finite Elements for Nonlinear Beams: The absolute nodal coordinate and geometrically exact formulations

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    Two of the most popular finite element formulations for solving nonlinear beams are the absolute nodal coordinate and the geometrically exact approaches. Both can be applied to problems with very large deformations and strains, but they differ substantially at the continuous and the discrete levels. In addition, implementation and run-time computational costs also vary significantly. In the current work, we summarize the main features of the two formulations, highlighting their differences and similarities, and perform numerical benchmarks to assess their accuracy and robustness. The article concludes with recommendations for the choice of one formulation over the other

    C-axis lattice dynamics in Bi-based cuprate superconductors

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    We present results of a systematic study of the c axis lattice dynamics in single layer Bi2Sr2CuO6 (Bi2201), bilayer Bi2Sr2CaCu2O8 (Bi2212) and trilayer Bi2Sr2Ca2Cu3O10 (Bi2223) cuprate superconductors. Our study is based on both experimental data obtained by spectral ellipsometry on single crystals and theoretical calculations. The calculations are carried out within the framework of a classical shell model, which includes long-range Coulomb interactions and short-range interactions of the Buckingham form in a system of polarizable ions. Using the same set of the shell model parameters for Bi2201, Bi2212 and Bi2223, we calculate the frequencies of the Brillouin-zone center phonon modes of A2u symmetry and suggest the phonon mode eigenvector patterns. We achieve good agreement between the calculated A2u eigenfrequencies and the experimental values of the c axis TO phonon frequencies which allows us to make a reliable phonon mode assignment for all three Bi-based cuprate superconductors. We also present the results of our shell model calculations for the Gamma-point A1g symmetry modes in Bi2201, Bi2212 and Bi2223 and suggest an assignment that is based on the published experimental Raman spectra. The superconductivity-induced phonon anomalies recently observed in the c axis infrared and resonant Raman scattering spectra in trilayer Bi2223 are consistently explained with the suggested assignment.Comment: 29 pages, 13 figure

    Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.

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    Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited

    Track D Social Science, Human Rights and Political Science

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

    Biofuels, greenhouse gases and climate change. A review

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    Representaçþes sociais sobre o corpo em estudantes de Medicina, Medellín, 2014] [Representaciones sociales sobre el cuerpo en estudiantes de Medicina, Medellín, 2014

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    Introduction: Philosophical and socio-anthropological discourses about the body have not been of interest in medical formation. Objective: To understand the social representations of the body in medical students, Medellin, 2014. Methods: Ethnography with 11 students selected by theoretical sampling. Social representations were studied with the procedural approach. Methodological rigor criteria of credibility, auditability and transferability were applied. Results: Three analytical categories were analyzed: 1) conceptions of the body which included the subcategories “biological” and “symbolic” dimensions of the body”; 2) importance of the body described from the subcategories “body as medium and object” and “body as definition of Ego”; 3) care of the body with three subcategories: “importance of self-care”, “the body of the other”, “self-care practices”. Conclusion: The organismic conception of the body reveals how medical students understand the other from strictly biological principles; epistemologically it is evident that students are Cartesian vectors lacking historical awareness about the representations of the body; politically and socially the group is aligned with neoliberal rationalities that vindicate marketization, modernization and individuation of the body. Š 2015, Universidad de Antioquia. All rights [email protected]

    A 7-year follow-up retrospective, international, multicenter study of insulin pump therapy in children and adolescents with type 1 diabetes

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    We evaluated the long-term glycemic control in children with type 1 diabetes, using continuous subcutaneous insulin infusion (CSII) for at least 5 years in three diabetes centers from three different countries: Canada, Italy and Spain. This was an observational retrospective multicenter cohort study. Subjects were included if they were followed at one of the participating centers, had type 1 diabetes, age 5-20 years at time of data collection and used CSII for more than 5 years. Data collected included gender, age, disease duration, age at CSII initiation, body mass index (BMI), hemoglobin A1c (HbA1c), insulin requirement and serious adverse events (SAE) at baseline and every 12 months during follow-up. One hundred fifteen patients were included in the study (55 % males), aged 5-20 years (mean: 13.5 \ub1 3.8 years), with mean diabetes duration of 6.3 \ub1 3.4 years, using CSII for mean of 6.9 \ub1 1.2 years (range 5-12 years.). HbA1c significantly improved after 1 year of CSII treatment and during follow-up (p = 0.02). When HbA1c was compared between countries, a difference was observed, with slightly lower values in Italy than in Canada and Spain (p = 0.04). When evaluated by gender, HbA1c was similar at baseline, but significantly improved only in males during all follow-up (p = 0.004). No significant differences were observed for BMI, insulin requirement or SAE. Insulin pump therapy is safe and effective in the pediatric population, although in this study, the major benefit in HbA1c was seen in males. The use of advanced pump features was associated with greater improvement in HbA1c

    Analyses of phenotypic and functional characteristics of CX3CR1-expressing natural killer cells

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    Summary We previously demonstrated a correlation between the frequency of CX3CR1-expressing human natural killer (NK) cells and disease activity in multiple sclerosis and showed that CX3CR1(high) NK cells were more cytotoxic than their CX3CR1(neg/low) counterparts. Here we aimed to determine whether human NK cell fractions defined by CX3CR1 represent distinct subtypes. Phenotypic and functional NK cell analyses revealed that, distinct from CX3CR1(high) , CX3CR1(neg/low) NK cells expressed high amounts of type 2 cytokines, proliferated robustly in response to interleukin-2 and promoted a strong up-regulation of the key co-stimulatory molecule CD40 on monocytes. Co-expression analyses of CX3CR1 and CD56 demonstrated the existence of different NK cell fractions based on the surface expression of these two surface markers, the CX3CR1(neg)  CD56(bright) , CX3CR1(neg)  CD56(dim) and CX3CR1(high)  CD56(dim) fractions. Additional investigations on the expression of NK cell receptors (KIR, NKG2A, NKp30 and NKp46) and the maturation markers CD27, CD62L and CD57 indicated that CX3CR1 expression of CD56(dim) discriminated between an intermediary CX3CR1(neg)  CD56(dim) and fully mature CX3CR1(high)  CD56(dim) NK cell fractions. Hence, CX3CR1 emerges as an additional differentiation marker that may link NK cell maturation with the ability to migrate to different organs including the central nervous system

    Geochemistry and Geochronology of the Guajira Eclogites, northern Colombia : evidence of a metamorphosed primitive Cretaceous Caribbean Island-arc

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    The chemical composition of eclogites, found as boulders in a Tertiary conglomerate from the Guajira Peninsula, Colombia suggests that these rocks are mainly metamorphosed basaltic andesites. They are depleted in LILE elements compared to MORB, have a negative Nb-anomaly and flat to enriched REE patterns, suggesting that their protoliths evolved in a subduction related tectonic setting. They show island-arc affinities and are similar to primitive islandarc rocks described in the Caribbean. The geochemical characteristics are comparable to low-grade greenschists from the nearby Etpana Terrane, which are interpreted as part of a Cretaceous intra-oceanic arc. These data support evidence that the eclogites and the Etpana terrane rocks formed from the same volcano-sedimentary sequence. Part of this sequence was accreted onto the margin and another was incorporated into the subduction channel and metamorphosed at eclogite facies conditions. 40Ar-39Ar ages of 79.2Âą1.1Ma and 82.2Âą2.5Ma determined on white micas, separated from two eclogite samples, are interpreted to be related to the cooling of the main metamorphic event. The formation of a common volcano-sedimentary protolith and subsequent metamorphism of these units record the ongoing Late Cretaceous continental subduction of the South American margin within the Caribbean intra-oceanic arc subduction zone. This gave way to an arc-continent collision between the Caribbean and the South American plates, where this sequence was exhumed after the Campanian
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