2,798 research outputs found

    Analytic Kramer kernels, Lagrange-type interpolation series and de Branges spaces

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    The classical Kramer sampling theorem provides a method for obtaining orthogonal sampling formulas. In particular, when the involved kernel is analytic in the sampling parameter it can be stated in an abstract setting of reproducing kernel Hilbert spaces of entire functions which includes as a particular case the classical Shannon sampling theory. This abstract setting allows us to obtain a sort of converse result and to characterize when the sampling formula associated with an analytic Kramer kernel can be expressed as a Lagrange-type interpolation series. On the other hand, the de Branges spaces of entire functions satisfy orthogonal sampling formulas which can be written as Lagrange-type interpolation series. In this work some links between all these ideas are established

    The Western European Acheulean: Reading variability at a regional scale

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    In the context of the Western European Acheulean Project, this study aims to characterize Acheulean technology in Western Europe through the analysis of handaxes and cleavers from 10 key sites (Britain 4, France 4, and Spain 2) to acquire a regional view of the occupation. The historically different systems used to categorize and analyze the data have made it difficult to compare results. Here we apply a unified and simple method (Western European Acheulean Project) that combines the traditional technological and metrical analysis of assemblages containing handaxes and cleavers with an in-depth geometric morphometric approach using three-dimensional models. This approach allows us to achieve a regional interpretation that identifies innovations through time and shaping strategies across the area. Our findings indicate the existence of two main technological groups in the sampled record: 1) northwestern and central France and Britain, from MIS 17/16 to MIS 11, and 2) Atlantic edge (Atapuerca in Spain and Menez-Dregan in France), from MIS 12/11 to MIS 8. Based on our technological analysis, the shaping of handaxes and cleavers was developed through time as a continuum of accumulative actions, with longer and more complex shaping strategies over time. Shaping technology shows traditions of manufacture over both time and geographical areas, which suggest cultural diffusion. Our geometric morphometric analysis further helped to identify not only general trends but also local adaptations in handaxe forms. Based on our findings, there were no apparent sudden innovations, but rather the application and development of specific techniques to refine size and shape

    The shape of our gut: Dissecting its impact on drug absorption in a 3D bioprinted intestinal model

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    The small intestine is a complex organ with a characteristic architecture and a major site for drug and nutrient absorption. The three-dimensional (3D) topography organized in finger-like protrusions called villi increases surface area remarkably, granting a more efficient absorption process. The intestinal mucosa, where this process occurs, is a multilayered and multicell-type tissue barrier. In vitro intestinal models are routinely used to study different physiological and pathological processes in the gut, including compound absorption. Still, standard models are typically two-dimensional (2D) and represent only the epithelial barrier, lacking the cues offered by the 3D architecture and the stromal components present in vivo, often leading to inaccurate results. In this work, we studied the impact of the 3D architecture of the gut on drug transport using a bioprinted 3D model of the intestinal mucosa containing both the epithelial and the stromal compartments. Human intestinal fibroblasts were embedded in a previously optimized hydrogel bioink, and enterocytes and goblet cells were seeded on top to mimic the intestinal mucosa. The embedded fibroblasts thrived inside the hydrogel, remodeling the surrounding extracellular matrix. The epithelial cells fully covered the hydrogel scaffolds and formed a uniform cell layer with barrier properties close to in vivo. In particular, the villus-like model revealed overall increased permeability compared to a flat counterpart composed by the same hydrogel and cells. In addition, the efflux activity of the P-glycoprotein (P-gp) transporter was significantly reduced in the villus-like scaffold compared to a flat model, and the genetic expression of other drugs transporters was, in general, more relevant in the villus-like model. Globally, this study corroborates that the presence of the 3D architecture promotes a more physiological differentiation of the epithelial barrier, providing more accurate data on drug absorbance measurements.Copyright © 2023. Published by Elsevier B.V

    Quantum Simulation of Spin Chains Coupled to Bosonic Modes with Superconducting Circuits

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    We propose the implementation of a digital quantum simulation of spin chains coupled to bosonic field modes in superconducting circuits. Gates with high fidelities allows one to simulate a variety of Ising magnetic pairing interactions with transverse field, Tavis-Cummings interaction between spins and a bosonic mode, and a spin model with three-body terms. We analyze the feasibility of the implementation in realistic circuit quantum electrodynamics setups, where the interactions are either realized via capacitive couplings or mediated by microwave resonators.Comment: Chapter in R. S. Anderssen et al. (eds.), Mathematics for Industry 11 (Springer Japan, 2015

    Intraoperative PaO2 is not related to the development of surgical site infections after major cardiac surgery

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    Producción CientíficaBackground: The perioperative use of high inspired oxygen fraction (FIO2) for preventing surgical site infections (SSIs) has demonstrated a reduction in their incidence in some types of surgery however there exist some discrepancies in this respect. The aim of this study was to analyze the relationship between PaO2 values and SSIs in cardiac patients. Methods: We designed a prospective study in which 1,024 patients undergoing cardiac surgery were analyzed. Results: SSIs were observed in 5.3% of patients. There was not significant difference in mortality at 30 days between patients with and without SSIs. In the uni and multivariate analysis no differences in function of the inspired oxygen fraction administrated were observed. Conclusions: We observed that the PaO2 in adult cardiac surgery patients was not related to SSI rate

    Evolutionary and pulsational properties of white dwarf stars

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    Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. They can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants. In this work, we review the essentials of the physics of white dwarf stars. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.Comment: 85 pages, 28 figures. To be published in The Astronomy and Astrophysics Revie

    LOGISTICS PERFORMANCE AND EXPORT COMPETITIVENESS: EUROPEAN EXPERIENCE

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    This article aims to analyse the importance of logistics performance in European Union (EU) exports over a sample period in order to detect possible advances on behalf of Member States. We will estimate several gravity equations using the Logistics Performance Index (LPI) and its components as characteristic proxy variables of trade facilitation. In order to avoid the possible heterogeneity caused by sample bias, we will employ the two-stage model proposed by Heckman. The estimations of the gravity models using the two-stage Heckman model for 26 EU countries lead to the conclusion that logistics were more important for exporting nations than importing nations in both 2005 and 2010, reinforcing the interest in the exporter side of the paper. In reference to the components of the LPI, Competence and Tracking have acquired greater importance in recent years, in keeping with the weak domestic demand in European countries and their search for new international markets.Puertas Medina, RM.; Martí Selva, ML.; Garcia Menendez, L. (2013). LOGISTICS PERFORMANCE AND EXPORT COMPETITIVENESS: EUROPEAN EXPERIENCE. Empirica. 1-14. doi:10.1007/s10663-013-9241-zS114Anderson JE (1979) A theorical foundation to the gravity equation. Am Econ Rev 69: 106–116 http://www.jstor.org/stable/1802501Anderson J, Van Wincoop E (2003) Gravity with gravitas: a solution to the border puzzle. Am Econ Rev 93:170–192. doi: 10.1257/000282803321455214Arvis JF, Mustra M, Ojala L, Shepherd B, Saslavsky D (2007) Connecting to compete: trade logistics in the global economy. World Bank, WashingtonArvis JF, Mustra M, Panzer J, Ojala L, Naula T (2010) Connecting to compete: trade logistics in the global economy. 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Rev Econ Stat 67: 474–481. http://www.jstor.org/stable/1928061Breuss F, Egger P (1999) How reliable are estimations of east-west trade potencials based on cross-section gravity analysis? Empirica 26:86–89. doi: 10.1023/A:1007011329676CILT (2012) Available at http://www.ciltuk.org.uk/pages/royalcharter . Accessed 02 Aug 2012Felipe J, Kumar U (2012) The role of trade facilitation in Central Asia: a gravity model. East Eur Econ 50:5–20. doi: 10.2753/EEE0012-875500401Heckman J (1979) Sample selection bias as a specification error. Econometrica 47: 153–161. http://www.jstor.org/stable/1912352Helpman E, Krugman P (1985) Market structure and foreign trade. Increasing returns, imperfect competition and the international economy. The MIT Press, Cambridge, MA/LondonHertel T, Mirza T (2009) The role of trade facilitation in South Asian economic integration. Study on intraregional trade and investment in South Asia. ADB, Mandaluyong CityHollweg C, Wong M-H (2009) Measuring regulatory restrictions in logistics services. ERIA Discussion Paper Series, no. 14Jane C–C (2011) Performance evaluation of logistic systems under cost and reliability considerations. Transp Res E-Log 47:130–137. doi: 10.1016/j.tre.2010.09.012Keskin MH (2012) The exigencies of the common logistics policy for European community and the deconstruction of the common transportation policy. Afr J Bus Manage 6:10697–10707. doi: 10.5897/AJBM11.1523Korinek J, Sourdin P (2011) To what extent are high-quality logistics services trade facilitating? Oecd trade policy working papers 108. OECD PublishingLangley C, Coyle J, Gibson B, Novak R, Bardi E (2008) Managing supply chain: a logistics approach. South–Western College Publishing, LondonMangan J, Lalwani C, Butcher C (2008) Global logistics and supply chain management. Wiley John & Sons, Inc., Hoboken, NJMartí ML, Puertas R, García L (2012) Relevance of trade facilitation in emerging countries′s export. J Int Trade Eco Dev. http://www.tandfonline.com/doi/abs/10.1080/09638199.2012.698639Requena F, Llano C (2010) The border effects in Spain: an industrial-level analysis. Empirica 37:455–476. doi: 10.1007/s10663-010-9123-6Rushton A, Oxley J, Croucher P (2009) The handbook of logistics and distribution management. Kogan Page, LondonVilko J, Karandassov B, Myller E (2011) Logistic infrastructure and its effects on economic development. China–USA Bus Rev 10:1152–1167World Bank (2010) Trade and transport facilitation assessment: a practical toolkit for country implementation. World Bank, Washingto

    Klebsiella pneumoniae is able to trigger epithelial-mesenchymal transition process in cultured airway epithelial cells

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    The ability of some bacterial pathogens to activate Epithelial-Mesenchymal Transition normally is a consequence of the persistence of a local chronic inflammatory response or depends on a direct interaction of the pathogens with the host epithelial cells. In this study we monitored the abilities of the K. pneumoniae to activate the expression of genes related to EMT-like processes and the occurrence of phenotypic changes in airway epithelial cells during the early steps of cell infection. We describe changes in the production of intracellular reactive oxygen species and increased HIF-1α mRNA expression in cells exposed to K. pneumoniae infection. We also describe the upregulation of a set of transcription factors implicated in the EMT processes, such as Twist, Snail and ZEB, indicating that the morphological changes of epithelial cells already appreciable after few hours from the K. pneumoniae infection are tightly regulated by the activation of transcriptional pathways, driving epithelial cells to EMT. These effects appear to be effectively counteracted by resveratrol, an antioxidant that is able to exert a sustained scavenging of the intracellular ROS. This is the first report indicating that strains of K. pneumoniae may promote EMT-like programs through direct interaction with epithelial cells without the involvement of inflammatory cells
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