41 research outputs found

    Modelling the Effects of Population Structure on Childhood Disease: The Case of Varicella

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    Realistic, individual-based models based on detailed census data are increasingly used to study disease transmission. Whether the rich structure of such models improves predictions is debated. This is studied here for the spread of varicella, a childhood disease, in a realistic population of children where infection occurs in the household, at school, or in the community at large. A methodology is first presented for simulating households with births and aging. Transmission probabilities were fitted for schools and community, which reproduced the overall cumulative incidence of varicella over the age range of 0–11 years old

    Real-time numerical forecast of global epidemic spreading: Case study of 2009 A/H1N1pdm

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    Background Mathematical and computational models for infectious diseases are increasingly used to support public-health decisions; however, their reliability is currently under debate. Real-time forecasts of epidemic spread using data-driven models have been hindered by the technical challenges posed by parameter estimation and validation. Data gathered for the 2009 H1N1 influenza crisis represent an unprecedented opportunity to validate real-time model predictions and define the main success criteria for different approaches. Methods We used the Global Epidemic and Mobility Model to generate stochastic simulations of epidemic spread worldwide, yielding (among other measures) the incidence and seeding events at a daily resolution for 3,362 subpopulations in 220 countries. Using a Monte Carlo Maximum Likelihood analysis, the model provided an estimate of the seasonal transmission potential during the early phase of the H1N1 pandemic and generated ensemble forecasts for the activity peaks in the northern hemisphere in the fall/winter wave. These results were validated against the real-life surveillance data collected in 48 countries, and their robustness assessed by focusing on 1) the peak timing of the pandemic; 2) the level of spatial resolution allowed by the model; and 3) the clinical attack rate and the effectiveness of the vaccine. In addition, we studied the effect of data incompleteness on the prediction reliability. Results Real-time predictions of the peak timing are found to be in good agreement with the empirical data, showing strong robustness to data that may not be accessible in real time (such as pre-exposure immunity and adherence to vaccination campaigns), but that affect the predictions for the attack rates. The timing and spatial unfolding of the pandemic are critically sensitive to the level of mobility data integrated into the model. Conclusions Our results show that large-scale models can be used to provide valuable real-time forecasts of influenza spreading, but they require high-performance computing. The quality of the forecast depends on the level of data integration, thus stressing the need for high-quality data in population-based models, and of progressive updates of validated available empirical knowledge to inform these models

    Organic-inorganic supramolecular solid catalyst boosts organic reactions in water

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    [EN] Coordination polymers and metal-organic frameworks are appealing as synthetic hosts for mediating chemical reactions. Here we report the preparation of a mesoscopic metal-organic structure based on single-layer assembly of aluminium chains and organic alkylaryl spacers. The material markedly accelerates condensation reactions in water in the absence of acid or base catalyst, as well as organocatalytic Michael-type reactions that also show superior enantioselectivity when comparing with the host-free transformation. The mesoscopic phase of the solid allows for easy diffusion of products and the catalytic solid is recycled and reused. Saturation transfer difference and two-dimensional H-1 nuclear Overhauser effect NOESY NMR spectroscopy show that non-covalent interactions are operative in these host-guest systems that account for substrate activation. The mesoscopic character of the host, its hydrophobicity and chemical stability in water, launch this material as a highly attractive supramolecular catalyst to facilitate (asymmetric) transformations under more environmentally friendly conditions.This work was funded by ERC-AdG-2014-671093-SynCatMatch and the Generalitat Valenciana (Prometeo). M.B. acknowledges the funding: CTQ2014-52633-P. The Severo Ochoa program (SEV-2012-0267) is thankfully acknowledged.GarcĂ­a GarcĂ­a, P.; Moreno RodrĂ­guez, JM.; DĂ­az Morales, UM.; Bruix, M.; Corma CanĂłs, A. (2016). Organic-inorganic supramolecular solid catalyst boosts organic reactions in water. Nature Communications. 7. https://doi.org/10.1038/ncomms10835S7Li, B. et al. A porous metal-organic framework with dynamic pyrimidine groups exhibiting record high methane storage working capacity. J. Am. Chem. Soc. 136, 6207–6210 (2014).Getman, R. B., Bae, Y.-S., Wilmer, C. E. & Snurr, R. Q. Review and analysis of molecular simulations of methane, hydrogen, and acetylene storage in metal–organic frameworks. Chem. Rev. 112, 703–723 (2012).Suh, M. P., Park, H. J., Prasad, T. K. & Lim, D.-W. Hydrogen storage in metal–organic frameworks. Chem. Rev. 112, 782–835 (2012).Li, B., Wen, H.-M., Zhou, W. & Chen, B. Porous metal-organic frameworks for gas storage and separation: what, how, and why? J. Phys. Chem. Lett. 5, 3468–3479 (2014).Li, J.-R., Sculley, J. & Zhou, H.-C. Metal–organic frameworks for separations. Chem. Rev. 112, 869–932 (2012).Cui, Y., Yue, Y., Qian, G. & Chen, B. Luminescent functional metal–organic frameworks. Chem. Rev. 112, 1126–1162 (2012).Yoon, M., Suh, K., Natarajan, S. & Kim, K. Proton conduction in metal–organic frameworks and related modularly built porous solids. Angew. Chem. Int. Ed. 52, 2688–2700 (2013).Kurmoo, M. Magnetic metal-organic frameworks. Chem. Soc. Rev. 38, 1353–1379 (2009).Horcajada, P. et al. Metal–organic frameworks in biomedicine. Chem. Rev. 112, 1232–1268 (2012).Liu, J. et al. Applications of metal-organic frameworks in heterogeneous supramolecular catalysis. Chem. Soc. Rev. 43, 6011–6061 (2014).Rowsell, J. L. C. & Yaghi, O. M. Metal–organic frameworks: a new class of porous materials. Micropor. Mesopor. Mat. 73, 3–14 (2004).Eubank, J. F. et al. The next chapter in MOF pillaring strategies: trigonal heterofunctional ligands to access targeted high-connected three dimensional nets, isoreticular platforms. J. Am. Chem. Soc. 133, 17532–17535 (2011).Rodenas, T. et al. Metal-organic framework nanosheets in polymer composite materials for gas separation. Nat. Mater. 14, 48–55 (2015).Chang, Z. et al. Rational construction of 3D pillared metal–organic frameworks: synthesis, structures, and hydrogen adsorption properties. Inorg. Chem. 50, 7555–7562 (2011).Cheetham, A. K., Rao, C. N. R. & Feller, R. K. Structural diversity and chemical trends in hybrid inorganic-organic framework materials. Chem. Commun. 4780–4795 (2006).Loiseau, T. et al. A rationale for the large breathing of the porous aluminum terephthalate (MIL-53) upon hydration. Chem. Eur. J. 10, 1373–1382 (2004).Senkovska, I. et al. New highly porous aluminium based metal-organic frameworks: Al(OH)(ndc) (ndc=2,6-naphthalene dicarboxylate) and Al (OH) (bpdc) (bpdc=4,4â€Č-biphenyl dicarboxylate). Micropor. Mesopor. Mat. 122, 93–98 (2009).Klein, N. et al. Structural flexibility and intrinsic dynamics in the M2(2,6-ndc)2(dabco) (M=Ni, Cu, Co, Zn) metal-organic frameworks. J. Mater. Chem. 22, 10303–10312 (2012).Hoffmann, H. C. et al. High-pressure in situ 129Xe NMR spectroscopy and computer simulations of breathing transitions in the metal–organic framework Ni2(2,6-ndc)2(dabco) (DUT-8(Ni). J. Am. Chem. Soc. 133, 8681–8690 (2011).Gu, J.-M., Kim, W.-S. & Huh, S. Size-dependent catalysis by DABCO-functionalized Zn-MOF with one-dimensional channels. Dalton Trans. 40, 10826–10829 (2011).Carson, C. G. et al. Synthesis and structure characterization of copper terephthalate metal–organic frameworks. Eur. J. Inorg. Chem. 2009, 2338–2343 (2009).Yang, Q. et al. Probing the adsorption performance of the hybrid porous MIL-68(Al): a synergic combination of experimental and modelling tools. J. Mater. Chem. 22, 10210–10220 (2012).Li, H. et al. Visible light-driven water oxidation promoted by host-guest interaction between photosensitizer and catalyst with a high quantum efficiency. J. Am. Chem. Soc. 137, 4332–4335 (2015).Hapiot, F., Bricout, H., Menuel, S., Tilloy, S. & Monflier, E. Recent breakthroughs in aqueous cyclodextrin-assisted supramolecular catalysis. Catal. Sci. Technol. 4, 1899–1908 (2014).Harada, A., Takashima, Y. & Nakahata, M. Supramolecular polymeric materials via cyclodextrin-guest interactions. Acc. Chem. Res. 47, 2128–2140 (2014).Cong, H. et al. Substituent effect of substrates on cucurbit[8]uril-catalytic oxidation of aryl alcohols. J. Mol. Catal. A Chem. 374-375, 32–38 (2013).Masson, E., Ling, X., Joseph, R., Kyeremeh-Mensah, L. & Lu, X. Cucurbituril chemistry: a tale of supramolecular success. RSC Adv. 2, 1213–1247 (2012).Song, F.-T., Ouyang, G.-H., Li, Y., He, Y.-M. & Fan, Q.-H. Metallacrown ether catalysts containing phosphine-phosphite polyether ligands for Rh-catalyzed asymmetric hydrogenation—enhancements in activity and enantioselectivity. Eur. J. Org. Chem. 2014, 6713–6719 (2014).Rebilly, J.-N. & Reinaud, O. Calixarenes and resorcinarenes as scaffolds for supramolecular metallo-enzyme mimicry. Supramol. Chem. 26, 454–479 (2014).Ajami, D., Liu, L. & Rebek, J. Jr Soft templates in encapsulation complexes. Chem. Soc. Rev. 44, 490–499 (2015).Corma, A. & Garcia, H. Supramolecular host-guest systems in zeolites prepared by ship-in-a-bottle synthesis. Eur. J. Inorg. Chem. 2004, 1143–1164 (2004).Kemp, D. S., Cox, D. D. & Paul, K. G. Physical organic chemistry of benzisoxazoles. IV. Origins and catalytic nature of the solvent rate acceleration for the decarboxylation of 3-carboxybenzisoxazoles. J. Am. Chem. Soc. 97, 7312–7318 (1975).Thorn, S. N., Daniels, R. G., Auditor, M. T. & Hilvert, D. Large rate accelerations in antibody catalysis by strategic use of haptenic charge. Nature 373, 228–230 (1995).Yoshizawa, M., Klosterman, J. K. & Fujita, M. Functional molecular flasks: new properties and reactions within discrete, self-assembled hosts. Angew. Chem. Int. Ed. 48, 3418–3438 (2009).Yoshizawa, M., Tamura, M. & Fujita, M. Diels-Alder in aqueous molecular hosts: unusual regioselectivity and efficient catalysis. Science 312, 251–254 (2006).Murase, T., Nishijima, Y. & Fujita, M. Cage-catalyzed knoevenagel condensation under neutral conditions in water. J. Am. Chem. Soc. 134, 162–164 (2012).Zhao, C., Toste, F. D., Raymond, K. N. & Bergman, R. G. Nucleophilic substitution catalyzed by a supramolecular cavity proceeds with retention of absolute stereochemistry. J. Am. Chem. Soc. 136, 14409–14412 (2014).Choi, M. et al. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts. Nature 461, 246–249 (2009).Loiseau, T. et al. MIL-96, a porous aluminum trimesate 3D structure constructed from a hexagonal network of 18-membered rings and ÎŒ3-Oxo-centered trinuclear units. J. Am. Chem. Soc. 128, 10223–10230 (2006).Bezverkhyy, I. et al. MIL-53(Al) under reflux in water: formation of Îł-AlO(OH) shell and H2BDC molecules intercalated into the pores. Micropor. Mesopor. Mat. 183, 156–161 (2014).Wang, L.-M. et al. Sodium stearate-catalyzed multicomponent reactions for efficient synthesis of spirooxindoles in aqueous micellar media. Tetrahedron 66, 339–343 (2010).List B. Science of Synthesis: Asymmetric Organocatalysis 1, Lewis Base and Acid Catalysts Georg Thieme Verlag (2012).He, T., Gu, Q. & Wu, X.-Y. Highly enantioselective Michael addition of isobutyraldehyde to nitroalkenes. Tetrahedron 66, 3195–3198 (2010).Avila, A., Chinchilla, R., Fiser, B., GĂłmez-Bengoa, E. & NĂĄjera, C. Enantioselective Michael addition of isobutyraldehyde to nitroalkenes organocatalyzed by chiral primary amine-guanidines. Tetrahedron Asymmetry 25, 462–467 (2014).Meyer, B. & Peters, T. NMR spectroscopy techniques for screening and identifying ligand binding to protein receptors. Angew. Chem. Int. Ed. 42, 864–890 (2003).Szczygiel, A., Timmermans, L., Fritzinger, B. & Martins, J. C. Widening the view on dispersant−pigment interactions in colloidal dispersions with saturation transfer difference NMR spectroscopy. J. Am. Chem. Soc. 131, 17756–17758 (2009).Basilio, N., MartĂ­n-Pastor, M. & GarcĂ­a-RĂ­o, L. Insights into the structure of the supramolecular amphiphile formed by a sulfonated calix[6]arene and alkyltrimethylammonium surfactants. Langmuir 28, 6561–6568 (2012).Mayer, M. & Meyer, B. Characterization of ligand binding by saturation transfer difference NMR spectroscopy. Angew. Chem. Int. Ed. 38, 1784–1788 (1999)

    Perivascular macrophages in health and disease

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    Macrophages are a heterogeneous group of cells that are capable of carrying out distinct functions in different tissues, as well as in different locations within a given tissue. Some of these tissue macrophages lie on, or close to, the outer (abluminal) surface of blood vessels and perform several crucial activities at this interface between the tissue and the blood. In steady-state tissues, these perivascular macrophages maintain tight junctions between endothelial cells and limit vessel permeability, phagocytose potential pathogens before they enter tissues from the blood and restrict inappropriate inflammation. They also have a multifaceted role in diseases such as cancer, Alzheimer disease, multiple sclerosis and type 1 diabetes. Here, we examine the important functions of perivascular macrophages in various adult tissues and describe how these functions are perturbed in a broad array of pathological conditions

    Nonlinear constrained principal component analysis in the quality control framework

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    Many problems in industrial quality control involve n measurements on\ud p process variables Xn;p. Generally, we need to know how the quality characteristics of a product behavior as process variables change. Nevertheless, there may be two problems: the linear hypothesis is not always respected and q quality variables Yn;q are not measured frequently because of high costs. B-spline transformation remove nonlinear hypothesis while principal component analysis with linear con-\ud straints (CPCA) onto subspace spanned by column X matrix. Linking Yn;q and\ud Xn;p variables gives us information on the Yn;q without expensive measurements and off-line analysis. Finally, there are few uncorrelated latent variables which contain the information about the Yn;q and may be monitored by multivariate control\ud charts. The purpose of this paper is to show how the conjoint employment of different statistical methods, such as B-splines, Constrained PCA and multivariate control charts allow a better control on product or service quality by monitoring directly\ud the process variables. The proposed approach is illustrated by the discussion of a real problem in an industrial process
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