176 research outputs found

    An inhibitory effect of D-Mannoheptulose on lactate formation in human whole blood in vitro

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    NumeraciĂłn errĂłnea en el original

    Effects of electrojet turbulence on a magnetosphere-ionosphere simulation of a geomagnetic storm

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    Ionospheric conductance plays an important role in regulating the response of the magnetosphere‐ionosphere system to solar wind driving. Typically, models of magnetosphere‐ionosphere coupling include changes to ionospheric conductance driven by extreme ultraviolet ionization and electron precipitation. This paper shows that effects driven by the Farley‐Buneman instability can also create significant enhancements in the ionospheric conductance, with substantial impacts on geospace. We have implemented a method of including electrojet turbulence (ET) effects into the ionospheric conductance model utilized within geospace simulations. Our particular implementation is tested with simulations of the Lyon‐Fedder‐Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere. We examine the impact of including ET‐modified conductances in a case study of the geomagnetic storm of 17 March 2013. Simulations with ET show a 13% reduction in the cross polar cap potential at the beginning of the storm and up to 20% increases in the Pedersen and Hall conductance. These simulation results show better agreement with Defense Meteorological Satellite Program observations, including capturing features of subauroral polarization streams. The field‐aligned current (FAC) patterns show little differences during the peak of storm and agree well with Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) reconstructions. Typically, the simulated FAC densities are stronger and at slightly higher latitudes than shown by AMPERE. The inner magnetospheric pressures derived from Tsyganenko‐Sitnov empirical magnetic field model show that the inclusion of the ET effects increases the peak pressure and brings the results into better agreement with the empirical model.This material is based upon work supported by NASA grants NNX14AI13G, NNX13AF92G, and NNX16AB80G. The National Center for Atmospheric Research is sponsored by the National Science Foundation. This work used the XSEDE and TACC computational facilities, supported by National Science Foundation grant ACI-1053575. We would like to acknowledge high-performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation. We thank the AMPERE team and the AMPERE Science Center for providing the Iridium derived data products. All model output, simulation codes, and analysis routines are being preserved on the NCAR High-Performance Storage System and will be made available upon written request to the lead author of this publication. (NNX14AI13G - NASA; NNX13AF92G - NASA; NNX16AB80G - NASA; National Science Foundation; ACI-1053575 - National Science Foundation

    Propagation of gamma rays and production of free electrons in air

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    A new concept of remote detection of concealed radioactive materials has been recently proposed \cite{Gr.Nusin.2010}-\cite{NusinSprangle}. It is based on the breakdown in air at the focal point of a high-power beam of electromagnetic waves produced by a THz gyrotron. To initiate the avalanche breakdown, seed free electrons should be present in this focal region during the electromagnetic pulse. This paper is devoted to the analysis of production of free electrons by gamma rays leaking from radioactive materials. Within a hundred meters from the radiation source, the fluctuating free electrons appear with the rate that may exceed significantly the natural background ionization rate. During the gyrotron pulse of about 10 microsecond length, such electrons may seed the electric breakdown and create sufficiently dense plasma at the focal region to be detected as an unambiguous effect of the concealed radioactive material.Comment: 27 pages, 10 figure

    A fibered description of the vector-valued spectrum

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    For Banach spaces X and Y we study the vector-valued spectrum (Formula presented.), that is the set of non null algebra homomorphisms from (Formula presented.) to (Formula presented.), which is naturally projected onto the closed unit ball of (Formula presented.). The aim of this article is to describe the fibers defined by this projection, searching for analytic balls and considering Gleason parts.Fil: Dimant, Veronica Isabel. Universidad de San Andrés. Departamento de Matemåticas y Ciencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Singer, Joaquín Camilo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemåtica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemåticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemåticas "Luis A. Santaló"; Argentin

    The mediating effect of task presentation on collaboration and children's acquisition of scientific reasoning

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    There has been considerable research concerning peer interaction and the acquisition of children's scientific reasoning. This study investigated differences in collaborative activity between pairs of children working around a computer with pairs of children working with physical apparatus and related any differences to the development of children's scientific reasoning. Children aged between 9 and 10 years old (48 boys and 48 girls) were placed into either same ability or mixed ability pairs according to their individual, pre-test performance on a scientific reasoning task. These pairs then worked on either a computer version or a physical version of Inhelder and Piaget's (1958) chemical combination task. Type of presentation was found to mediate the nature and type of collaborative activity. The mixed-ability pairs working around the computer talked proportionally more about the task and management of the task; had proportionally more transactive discussions and used the record more productively than children working with the physical apparatus. Type of presentation was also found to mediated children's learning. Children in same ability pairs who worked with the physical apparatus improved significantly more than same ability pairs who worked around the computer. These findings were partially predicted from a socio-cultural theory and show the importance of tools for mediating collaborative activity and collaborative learning

    Comparison of predictive estimates of high‐latitude electrodynamics with observations of global‐scale Birkeland currents

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    Two of the geomagnetic storms for the Space Weather Prediction Center Geospace Environment Modeling challenge occurred after data were first acquired by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). We compare Birkeland currents from AMPERE with predictions from four models for the 4–5 April 2010 and 5–6 August 2011 storms. The four models are the Weimer (2005b) field‐aligned current statistical model, the Lyon‐Fedder‐Mobarry magnetohydrodynamic (MHD) simulation, the Open Global Geospace Circulation Model MHD simulation, and the Space Weather Modeling Framework MHD simulation. The MHD simulations were run as described in Pulkkinen et al. (2013) and the results obtained from the Community Coordinated Modeling Center. The total radial Birkeland current, ITotal, and the distribution of radial current density, Jr, for all models are compared with AMPERE results. While the total currents are well correlated, the quantitative agreement varies considerably. The Jr distributions reveal discrepancies between the models and observations related to the latitude distribution, morphologies, and lack of nightside current systems in the models. The results motivate enhancing the simulations first by increasing the simulation resolution and then by examining the relative merits of implementing more sophisticated ionospheric conductance models, including ionospheric outflows or other omitted physical processes. Some aspects of the system, including substorm timing and location, may remain challenging to simulate, implying a continuing need for real‐time specification.Key PointsPresents the first comparison between observed field‐aligned currents and models previously evaluated for space weather operational useThe model and observed integrated currents are well correlated, but the ratio between them ranges from 1/3 to 3The 2‐D current densities are weakly correlated with observations implying significant areas for improvements in the modelsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136469/1/swe20415_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136469/2/swe20415.pd

    Modeling Ionospheric Absorption Modified by Anomalous Heating During Substorms

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    Abstract. Riometers monitor the changes in ionospheric conductivity by measuring the absorption of very high frequency radio noise of galactic origin passing through the ionosphere. In this Letter the absorption of radio signals by a thin layer of ionospheric plasma, produced by ionization due to energetic precipitating electrons, is modeled by taking into account strong turbulent heating caused by instabilities. The precipitating electron population is obtained from a global MHD simulation of the magnetosphere, along with the electric fields which excite the Farley-Buneman instability and lead to turbulent electron heating. A comparison, the first of its kind, of the data from polar and sub-auroral riometers for the magnetic cloud event of January 10, 1997 shows good agreement. The ionospheric conductance modified by turbulent electron heating can be used to improve the magnetosphereionosphere coupling in the current global MHD models

    Surveying the spirit of absolute summability on multilinear operators and homogeneous polynomials

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    [EN] We draw a fundamental compendium of the most valuable results of the theory of summing linear operators and detail those that are not shared by known multilinear and polynomial extensions of absolutely summing linear operators. The lack of such results in the theory of non-linear summing operators justifies the introduction of a class of polynomials and multilinear operators that satisfies at once all related non-linear results. Surprisingly enough, this class, defined by means of a summing inequality, happens to be the well known ideal of composition with a summing operator.D. Pellegrino acknowledges with thanks the support of CNPq Grant 401735/2013-3-PVE (Linha 2)-Brazil. P. Rueda acknowledges with thanks the support of the Ministerio de Economia y Competitividad (Spain) MTM2011-22417. E. A. Sanchez Perez acknowledges with thanks the support of the Ministerio de Economia y Competitividad (Spain) MTM2012-36740-C02-02.Pellegrino, D.; Rueda, P.; SĂĄnchez PĂ©rez, EA. (2016). Surveying the spirit of absolute summability on multilinear operators and homogeneous polynomials. Revista de la Real Academia de Ciencias Exactas FĂ­sicas y Naturales Serie A MatemĂĄticas. 110(1):285-302. https://doi.org/10.1007/s13398-015-0224-8S2853021101Achour, D., Dahia, E., Rueda, P., SĂĄnchez-PĂ©rez, E.A.: Factorization of absolutely continuous polynomials. J. Math. Anal. Appl. 405(1), 259–270 (2013)Albiac, F., Kalton, N.: Topics in Banac Space Theory. Springer, Berlin (2005)Alencar, R., Matos, M.C.: Some classes of multilinear mappings between Banach spaces, Publicaciones del Departamento de AnĂĄlisis MatemĂĄtico 12, Universidad Complutense Madrid (1989)Bombal, F., PĂ©rez-GarcĂ­a, D., Villanueva, I.: Multilinear extensions of Grothendieck’s theorem. Q. J. Math. 55(4), 441–450 (2004)Botelho, G., Braunss, H.-A., Junek, H., Pellegrino, D.: Holomorphy types and ideals of multilinear mappings. Studia Math. 177, 43–65 (2006)Botelho, G., Pellegrino, D.: Scalar-valued dominated polynomials on Banach spaces. Proc. Am. Math. Soc. 134, 1743–1751 (2006)Botelho, G., Pellegrino, D.: Absolutely summing polynomials on Banach spaces with unconditional basis. J. Math. Anal. Appl. 321, 50–58 (2006)Botelho, G., Pellegrino, D.: Coincidence situations for absolutely summing non-linear mappings. Port. Math. (N.S.) 64(2), 175–191 (2007)Botelho, G., Pellegrino, D., Rueda, P.: Pietsch’s factorization theorem for dominated polynomials. J. Funct. Anal. 243(1), 257–269 (2007)Botelho, G., Pellegrino, D., Rueda, P.: On composition ideals of multilinear mappings and homogeneous polynomials. Publ. Res. Inst. Math. Sci. 43(4), 1139–1155 (2007)Botelho, G., Pellegrino, D., Rueda, P.: A unified Pietsch domination theorem. J. Math. Anal. Appl. 365, 269–276 (2010)Botelho, G., Pellegrino, D., Rueda, P.: Dominated polynomials on infinite dimensional spaces. Proc. Am. Math. Soc. 138(1), 209–216 (2010)Botelho, G., Pellegrino, D., Rueda, P.: Cotype and absolutely summing linear operators. Math. Z. 267(1–2), 1–7 (2011)Botelho, G., Pellegrino, D., Rueda, P.: On Pietsch measures for summing operators and dominated polynomials. Linear Multilinear Algebra 62(7), 860–874 (2014)ÇalÄ±ĆŸkan, E., Pellegrino, D.M.: On the multilinear generalizations of the concept of absolutely summing operators. Rocky Mountain J. Math. 37, 1137–1154 (2007)Carando, D., Dimant, V.: On summability of bilinear operators. Math. Nachr. 259, 3–11 (2003)Carando, D., Dimant, V., Muro, S.: Coherent sequences of polynomial ideals on Banach spaces. Math. Nachr. 282, 1111–1133 (2009)Defant, A., Floret, K.: Tensor norms and operator ideals. North-Holland Mathematics Studies, 176. North-Holland Publishing Co., Amsterdam (1993)Diestel, J., Jarchow, H., Tonge, A.: Absolutely summing operators. Cambridge University Press, Cambridge (1995)Dimant, V.: Strongly pp p -summing multilinear operators. J. Math. Anal. Appl. 278, 182–193 (2003)Dineen, S.: Complex analysis on infinite-dimensional spaces. Springer, London (1999)Fabian, M., HĂĄjek, P., Montesinos-SantalucĂ­a, V., Pelant, J., Zizler, V.: Functional analysis and infinite-dimensional geometry. CMS Books in Mathematics/Ouvrages de MathĂ©matiques de la SMC, 8. Springer, New York (2001)Floret, K.: Natural norms on symmetric tensor products of normed spaces. Note Mat. 17, 153–188 (1997)Geiss, H.: Ideale multilinearer Abbildungen. Diplomarbeit, Brandenburgische Landeshochschule (1985)Grothendieck, A.: RĂ©sumĂ© de la thĂ©orie mĂ©trique des produits tensoriels topologiques (French). Bol. Soc. Mat. SĂŁo Paulo 8, 1–79 (1953)Jarchow, H., Palazuelos, C., PĂ©rez-GarcĂ­a, D., Villanueva, I.: Hahn-Banach extension of multilinear forms and summability. J. Math. Anal. Appl. 336, 1161–1177 (2007)Lindenstrauss, J., PeƂczyƄski, A.: Absolutely summing operators in Lp{\cal L}_{p} L p spaces and their applications. Studia Math. 29, 275–326 (1968)Matos, M.C.: Absolutely summing holomorphic mappings. Anais da Academia Brasileira de CiĂȘncias 68, 1–13 (1996)Matos, M.C.: Fully absolutely summing and Hilbert–Schmidt multilinear mappings. Collectanea Math. 54, 111–136 (2003)Matos, M.C.: Nonlinear absolutely summing mappings. Math. Nachr. 258, 71–89 (2003)MelĂ©ndez, Y., Tonge, A.: Polynomials and the Pietsch domination theorem. Proc. R. Irish Acad. Sect. A 99, 195–212 (1999)Montanaro, A.: Some applications of hypercontractive inequalities in quantum information theory. J. Math. Phys. 53(12), 122–206 (2012)Mujica, J.: Complex analysis in Banach spaces. Dover Publications, Mineola (2010)Pellegrino, D.: Cotype and absolutely summing homogeneous polynomials in Lp{\cal L}_{p} L p spaces. Studia Math. 157, 121–131 (2003)Pellegrino, D., Ribeiro, J.: On multi-ideals and polynomial ideals of Banach spaces: a new approach to coherence and compatibility. Monatsh. Math. 173(3), 379–415 (2014)Pellegrino, D., Santos, J.: A general Pietsch domination theorem. J. Math. Anal. Appl. 375, 371–374 (2011)Pellegrino, D., Santos, J.: Absolutely summing multilinear operators: a panorama. Quaest. Math. 34(4), 447–478 (2011)Pellegrino, D., Santos, J.: On summability of nonlinear mappings: a new approach. Math. Z. 270(1–2), 189–196 (2012)Pellegrino, D., Santos, J., Seoane-SepĂșlveda, J.B.: Some techniques on nonlinear analysis and applications. Adv. Math. 229, 1235–1265 (2012)PĂ©rez-GarcĂ­a, D.: David Comparing different classes of absolutely summing multilinear operators. Arch. Math. (Basel) 85(3), 258–267 (2005)Pietsch, A.: Absolut p-summierende Abbildungen in normierten RĂ€umen. (German) Studia Math. 28, 333–353 (1966/1967)Pietsch, A.: Ideals of multilinear functionals (designs of a theory). Proceedings of the second international conference on operator algebras, ideals, and their applications in theoretical physics (Leipzig, 1983), 185–199, Teubner-Texte Math., 67, Teubner, Leipzig, (1984)Pisier, G.: Grothendieck’s theorem, past and present. Bull. Am. Math. Soc. (N.S.) 49(2), 237–323 (2012)Rueda, P., SĂĄnchez-PĂ©rez, E.A.: Factorization of pp p -dominated polynomials through LpL^{p} L p -spaces. Michigan Math. J. 63(2), 345–353 (2014)Rueda, P., SĂĄnchez-PĂ©rez, E.A.: Factorization theorems for homogeneous maps on Banach function spaces and approximation of compact operators. Mediterr. J. Math. 12(1), 89–115 (2015)Ryan, R.A.: Applications of Topological Tensor Products to Infinite Dimensional Holomorphy, Ph.D. Thesis, Trinity College, Dublin, (1980
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