1,804 research outputs found

    A Survey on q-Polynomials and their Orthogonality Properties

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    In this paper we study the orthogonality conditions satisfied by the classical q-orthogonal polynomials that are located at the top of the q-Hahn tableau (big q-jacobi polynomials (bqJ)) and the Nikiforov-Uvarov tableau (Askey-Wilson polynomials (AW)) for almost any complex value of the parameters and for all non-negative integers degrees. We state the degenerate version of Favard's theorem, which is one of the keys of the paper, that allow us to extend the orthogonality properties valid up to some integer degree N to Sobolev type orthogonality properties. We also present, following an analogous process that applied in [16], tables with the factorization and the discrete Sobolev-type orthogonality property for those families which satisfy a finite orthogonality property, i.e. it consists in sum of finite number of masspoints, such as q-Racah (qR), q-Hahn (qH), dual q-Hahn (dqH), and q-Krawtchouk polynomials (qK), among others. -- [16] R. S. Costas-Santos and J. F. Sanchez-Lara. Extensions of discrete classical orthogonal polynomials beyond the orthogonality. J. Comp. Appl. Math., 225(2) (2009), 440-451Comment: 3 Figures, 3 tables, in a 22 pages manuscrip

    Who is willing to pay for science? On the relationship between public perception of science and the attitude to public funding of science

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    This article examines the relationship between the general public's understanding of science and the attitude towards public funding of scientific research. It applies a multivariate and discriminant analysis (Wilks' Lambda), in addition to a more commonly used bivariate analysis (Cramer's V), to data compiled from the Third National Survey on the Social Perception of Science and Technology in Spain (FECYT, 2006). The general conclusion is that the multivariate analysis produces information complementary to the bivariate analysis, and that the variables commonly applied in public perception studies have limited predictive value with respect to the attitude towards public funding of scientific research. Keywords: public attitude to science, public funding of science, public perception of scienc

    Microstructural evolution of Ti-6Al-4V during the sintering of microspheres of Ti for orthopedic implants

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    [EN] There are also important complementary stabilization treatments of the microstructure by means of controlled cooling at high speeds it avoids the formation of beta phases in grain boundaries, at the same time that avoid the broken-up of the Widmanstaetten structure, developing in an increase in mechanical resistance and fatigue resistance of the prosthesis. (C) 2003 Elsevier Science B.V. All rights reserved.Amigó, V.; Salvador Moya, MD.; Romero, F.; Solves-Camallonga, C.; Moreno, J. (2003). Microstructural evolution of Ti-6Al-4V during the sintering of microspheres of Ti for orthopedic implants. Journal of Materials Processing Technology. 141(1):117-122. https://doi.org/10.1016/S0924-0136(03)00243-7117122141

    Understanding mountain soils : a contribution from mountain areas to the International Year of Soils 2015

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    A volcanic tuff rock known as cangahua (Ecuador) or tepetate (Mexico) is found throughout the Andes. Problems have arisen as the layers of light but fragile soil that once covered the tuff have been lost for both natural (environmental) reasons and because of over-cultivation. When the soil is gone, the tuff is impermeable and sterile. Now, a project in Ecuador has determined that the tuff itself can be reclaimed and is supporting a programme that sends bulldozers to the tuff regions to break up the rock and create a new fertile soil

    Electron Spin Resonance Above Tc In Layered Manganites

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    We have performed electron spin resonance (ESR) and dc magnetization measurements on single crystals of La2(1-x)Sr1+2xMn2O7 up to 800 K with special emphasis on the x = 0.4 composition. The ESR linewidth shows behavior similar to that observed in the three-dimensional perovskites and above ∼500 K can be described by a universal expression ΔHpp(T)=[C/Tχ(T)]ΔHpp (∞). The linewidth and the resonance field become anisotropic below ∼500 K. The anisotropy in the resonance field is proportional to the magnetization M, and we concluded that it is intrinsic to the system. We show that demagnetization effects can explain only part of the anisotropy. The remainder arises from short-range uniaxial terms in the Hamiltonian that are associated with the crystal field and Dzialozhinsky-Moriya interactions. The anisotropy in the linewidth is attributed to the easy-plane ferromagnetic ordering, which also arises from the short-range anisotropy.631717441311744136Ruddlesden, S.N., Popper, P., (1958) Acta Crystallogr., 11, p. 54Moritomo, Y., Asamitsu, A., Kuwahara, H., Tokura, Y., (1996) Nature (London), 380, p. 141Causa, M.T., Tovar, M., Caneiro, A., Prado, F., Ibanez, G., Ramos, C.A., Butera, A., Oseroff, S.B., (1998) Phys. Rev. B, 58, p. 3233Causa, M.T., Alejandro, G., Tovar, M., Pagliuso, P.G., Rettori, C., Oseroff, S.B., Subramanian, M.A., (1999) J. Appl. Phys., 85, p. 5408Huber, D.L., Alejandro, G., Caneiro, A., Causa, M.T., Prado, F., Tovar, M., Oseroff, S.B., (1999) Phys. Rev. B, 60, p. 12155Oseroff, S.B., Moreno, N.O., Pagliuso, P.G., Rettori, C., Huber, D.L., Gardner, J.S., Sarrao, J.L., Alascio, B.R., (2000) J. Appl. Phys., 87, p. 5810Seehra, M.S., Ibrahim, M.M., Babu, V.S., Srinivasan, G., (1996) J. Phys.: Condens. Matter, 8, p. 11283Dominguez, M., Lofland, S.E., Bhagat, S.M., Raychaudhuri, A.K., Ju, H.L., Venkates, T., Greene, R.L., (1996) Solid State Commun., 97, p. 193Lofland, S.E., Kim, P., Dahiroc, P., Bhagat, S.M., Tyagi, S.D., Karabashev, S.G., Shultyatev, D.A., Mukovskii, Y., (1997) Phys. Lett. A, 233, p. 476Kimura, T., Tomioka, Y., Kuwahara, H., Asamitsu, A., Tamura, M., Tokura, Y., (1996) Science, 274, p. 1698Perring, T.G., Aeppli, G., Moritomo, Y., Tokura, Y., (1997) Phys. Rev. Lett., 78, p. 3197Zhou, J.-S., Goodenough, J.B., Mitchell, J.F., (1998) Phys. Rev. B, 58, p. 579Zhou, J.-S., Goodenough, J.B., (1998) Phys. Rev. Lett., 80, p. 2665Kelley, T.M., Argyriou, D.N., Robinson, R.A., Nakotte, H., Mitchell, J.F., Osbron, R., Jorgensen, J.D., (1998) Physica B, 241-243, p. 439Heffner, R.H., MacLaughlin, D.E., Nieuwenhuys, G.J., Kimura, T., Luke, G.M., Tokura, Y., Uemura, Y.J., (1998) Phys. Rev. Lett., 81, p. 1706Potter, C.D., Swiatek, M., Bader, S.D., Argyriou, D.N., Mitchell, J.F., Miller, D.J., Hinks, D.G., Jorgensen, J.D., (1998) Phys. Rev. B, 57, p. 72Chauvet, O., Goglio, G., Molinie, P., Corraze, B., Brohan, L., (1998) Phys. Rev. Lett., 81, p. 1102Hirota, K., Moritomo, Y., Fujioka, H., Kubota, M., Yoshizawa, H., Endoh, Y., (1998) J. Phys. Soc. Jpn., 67, p. 3380Li, J.Q., Matsui, Y., Kimura, T., Tokura, Y., (1998) Phys. Rev. B, 57, pp. R3205Kimura, T., Kumai, R., Tokura, Y., Li, J.Q., Matsui, Y., (1998) Phys. Rev. B, 58, p. 11081Hayashi, T., Miura, N., Tokunaga, M., Kimura, T., Tokura, Y., (1998) J. Phys.: Condens. Matter, 10, p. 11525Suryanarayanan, R., Dhalenne, G., Revcolevschi, A., Prellier, W., Renard, J.P., Dupas, C., Caliebe, W., Chatterji, T., (2000) Solid State Commun., 113, p. 267Kubota, M., Fujioka, H., Ohoyama, K., Hirota, K., Moritomo, Y., Yoshizawa, H., Endoh, Y., (1999) J. Phys. Chem. Solids, 60, p. 116Bhagat, S.M., Lofland, S.E., Mitchell, J.F., (1999) Phys. Lett. A, 259, p. 326Kittel, C., (1997) Introduction to Solid State Physics, , Wiley, New YorkOkochi, M., (1970) J. Phys. Soc. Jpn., 28, p. 897Victoria, C., Barker, R.C., Yelon, A., (1967) Phys. Rev. Lett., 19, p. 792Nagata, K., (1976) J. Phys. Soc. Jpn., 40, p. 1209Nagata, K., Yamamoto, I., Takano, H., Yokozawa, Y., (1977) J. Phys. Soc. Jpn., 43, p. 857. , and references thereinHuber, D.L., Seehra, M.S., (1976) Phys. Status Solidi B, 74, p. 145Stanger, J.-L., Andre, J.-J., Turek, P., Hosokoshi, Y., Tamura, M., Kinoshita, M., Rey, P., Veciana, J., (1997) Phys. Rev. B, 55, p. 8398Van Vleck, J.H., (1950) Phys. Rev., 78, p. 266Kittel, C., (1948) Phys. Rev., 73, p. 15

    Alcoholic liver disease confers a worse prognosis than HCV infection and non-alcoholic fatty liver disease among patients with cirrhosis: An observational study.

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    Cirrhosis is a heterogeneous clinical condition that includes patients at wide-ranging stages of severity. The role of the underlying liver disease on patient prognosis remains unclear. To assess the impact of the underlying liver disease on the occurrence of hepatocellular carcinoma (HCC) and death. Data related to the occurrence of HCC and death were collected during a 21-year period among patients with cirrhosis related to alcoholic liver disease (ALD) (n = 529), chronic hepatitis C virus (HCV) infection (n = 145) or non-alcoholic fatty liver disease (NAFLD) (n = 78). At inclusion, ALD patients were younger than HCV and NAFLD patients (56 vs. 67 vs. 63 years; p<0.001) and had worse liver function (percent of patients with Child-Pugh stages B or C: 48% vs. 8% vs. 17%; p<0.001). During follow-up, 85 patients developed HCC and 379 died. The 10-year cumulative incidence rate of HCC was lower in ALD patients than in HCV and NAFLD patients (8.4% vs. 22.0% vs. 23.7%; p<0.001). The 10-year cumulative incidence rates of mortality were not statistically different between ALD, HCV and NAFLD patients (58.1% vs. 47.7% vs. 49.9%; p = 0.078). Alcohol abstinence and viral eradication were associated with reduced mortality among ALD and HCV patients, respectively. In multivariate analyses, ALD was associated with a reduced risk of HCC (0.39; 95% CI, 0.20-0.76; p = 0.005) but with a higher risk of mortality (1.53; 95% CI, 1.20-1.95; p<0.001). ALD patients died more frequently from decompensation of cirrhosis. Despite a lower incidence of HCC, patients with ALD-related cirrhosis have a worse outcome than those with chronic HCV infection or NAFLD-related cirrhosis

    Metagenomic analysis of viruses, bacteria and protozoa in irrigation water

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    [EN] Viruses (e.g., noroviruses and hepatitis A and E virus), bacteria (e.g., Salmonella spp. and pathogenic Escherichia coli) and protozoa (e.g., Cryptosporidium parvum and Giardia intestinalis) are well-known contributors to food-borne illnesses linked to contaminated fresh produce. As agricultural irrigation increases the total amount of water used annually, reclaimed water is a good alternative to reduce dependency on conventional irrigation water sources. European guidelines have established acceptable concentrations of certain pathogens and/or indicators in irrigation water, depending on the irrigation system used and the irrigated crop. However, the incidences of food-borne infections are known to be underestimated and all the different pathogens contributing to these infections are not known. Next-generation sequencing (NGS) enables the determination of the viral, bacterial and protozoan populations present in a water sample, providing an opportunity to detect emerging pathogens and develop improved tools for monitoring the quality of irrigation water. This is a descriptive study of the virome, bacteriome and parasitome present in different irrigation water sources. We applied the same concentration method for all the studied samples and specific metagenomic approaches to characterize both DNA and RNA viruses, bacteria and protozoa. In general, most of the known viral species corresponded to plant viruses and bacteriophages. Viral diversity in river water varied over the year, with higher bacteriophage prevalences during the autumn and winter. Reservoir water contained Enterobacter cloacae, an opportunistic human pathogen and an indicator of fecal contamination, as well as Naegleria australiensis and Naegleria clarki. Hepatitis E virus and Naegleria fowleri, emerging human pathogens, were detected in groundwater. Reclaimed water produced in a constructed wetland system presented a virome and bacteriome that resembled those of freshwater samples (river and reservoir water). Viral, bacterial and protozoan pathogens were occasionally detected in the different irrigation water sources included in this study, justifying the use of improved NGS techniques to get a comprehensive evaluation of microbial species and potential environmental health hazards associated to irrigation water.This work was supported through a grant funded by the Spanish Ministry of Economy and Competitiveness (MINECO) in the frame of the collaborative international consortium JPIW2013-095-C03-01, JPIW2013-095-C03-02 and JPIW2013-095-C03-03 of the Water Challenges for a Changing World Joint Programming Initiative (Water JPI) Pilot Call and partially by AGL2017-86797-C2-1-R. Silvia Bofill-Mas is a Serra-Hunter fellow at the University of Barcelona.Rusiñol, M.; Martinez-Puchol, S.; Timoneda, N.; Fernandez-Cassi, X.; Pérez-Cataluña, A.; Fernández-Bravo, A.; Moreno-Mesonero, L.... (2020). Metagenomic analysis of viruses, bacteria and protozoa in irrigation water. International Journal of Hygiene and Environmental Health. 224. https://doi.org/10.1016/j.ijheh.2019.113440S22

    Determinación del estado hídrico en viña a través de imágenes RGB y multiespectrales adquiridas por un VANT

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    La teledetección se ha convertido en una herramienta muy utilizada en la agricultura de precisión. La existencia de sensores ligeros, calibrados geométrica y radiométricamente, ha hecho que los vehículos aéreos no tripulados (VANTs) sean una de las plataformas más utilizadas en teledetección por obtener datos de muy alta resolución espacial y temporal. En el marco de la viticultura de precisión, haciendo uso de VANTs para la obtención de imágenes aéreas de la cubierta vegetal que proporcionen información agronómicamente útil para hacer un manejo y una gestión del riego sostenible y eficiente frente a la escasez hídrica existente principalmente en zonas áridas y semiáridas, se llevó a cabo un estudio en un viñedo localizado en Fuente-Álamo (Albacete) durante 2018 y 2019. Para obtener un amplio rango de condiciones de estado hídrico de la vid, varias estrategias de riego fueron aplicadas incluyendo regímenes con diferentes niveles de salinidad del agua, estableciendo diferencias en el estado hídrico de la cepa. Los vuelos se hicieron a lo largo del ciclo fenológico usando sensores convencionales (o RGB -red, green, blue-) y multiespectrales a bordo de un VANT, obteniendo ortoimágenes. Estas ortoimágenes fueron segmentadas para incluir solo la vegetación obteniendo el grado de cobertura verde como un parámetro geométrico representativo del desarrollo vegetal del cultivo. El potencial hídrico de tallo fue medido a mediodía con cámaras de presión, y la integral de estrés hídrico fue calculada a partir de estas medidas de estado hídrico, como una variable representativa del efecto acumulado de la intensidad y duración del estrés hídrico desde el comienzo del ciclo de desarrollo hasta el momento de la medida. Modelos de regresión lineal simple usando índices de vegetación basados en la respuesta espectral de la vegetación y el grado de cobertura verde fueron evaluados para predecir la integral de estrés hídrico. Técnicas de regresión no lineal usando redes neuronales artificiales con bandas de los sensores multiespectral y RGB y el grado de cobertura verde como variables predictoras de la integral de estrés hídrico también fueron empleadas. Ambos modelos mostraron que los datos del rango visible (pese a la menor reflectividad de la vegetación en este rango espectral) fueron más útiles para predecir la integral de estrés hídrico que los datos del rango multiespectral, que consideran la reflectividad en el red-edge y en el infrarrojo cercano, proporcionando mejores resultados los modelos no lineales de redes neuronales artificiales con valores de R2 próximos a 1 y errores relativos de 1.5 % o ligeramente superiores. La mayor resolución espacial, calidad radiométrica, facilidad de uso de la cámara RGB, su menor precio y fácil procesamiento de las imágenes RGB hace que estos sensores, utilizados en menor medida con usos agrícolas, sean una buena opción para usarse en la predicción del estado hídrico en viña

    Filling a blank on the map: 60 years of fisheries in Equatorial Guinea

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    Despite a scarcity of pertinent information, it has been possible to reconstruct time series of marine fisheries catches for Equatorial Guinea from 1950 to 2010 using per capita fish consumption and population numbers for small-scale fisheries, catch rates and number of vessels for industrial fisheries and discard rates to estimate the discarded bycatch. Small-scale fisheries, industrial large-scale fisheries, domestic and legal and illegal foreign fisheries and their discards are all included. Total catches were estimated at 2.7 million tonnes over the time period considered, of which 653 000 t were caught domestically compared to 187 000 t reported by FAO. This shows that fisheries have more importance for Equatorial Guinea's food security than the official data suggest. In contrast to what is suggested by official figures, fisheries were shown to be strongly impacted by civil and political unrest; notably, they declined overall because of civil and political conflicts, socio-demographic dynamics, and a growing role of the newly discovered oil resources, which directly and indirectly threaten the food security of the people of Equatorial Guinea

    Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

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    The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi
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