614 research outputs found
Spatiotemporal chaotic dynamics of solitons with internal structure in the presence of finite-width inhomogeneities
We present an analytical and numerical study of the Klein-Gordon kink-soliton
dynamics in inhomogeneous media. In particular, we study an external field that
is almost constant for the whole system but that changes its sign at the center
of coordinates and a localized impurity with finite-width. The soliton solution
of the Klein-Gordon-like equations is usually treated as a structureless
point-like particle. A richer dynamics is unveiled when the extended character
of the soliton is taken into account. We show that interesting spatiotemporal
phenomena appear when the structure of the soliton interacts with finite-width
inhomogeneities. We solve an inverse problem in order to have external
perturbations which are generic and topologically equivalent to well-known
bifurcation models and such that the stability problem can be solved exactly.
We also show the different quasiperiodic and chaotic motions the soliton
undergoes as a time-dependent force pumps energy into the traslational mode of
the kink and relate these dynamics with the excitation of the shape modes of
the soliton.Comment: 10 pages Revtex style article, 22 gziped postscript figures and 5 jpg
figure
Dating archaeological copper using electrochemical impedance spectroscopy. Comparison with voltammetry of microparticles dating
[EN] A methodology for dating copper/bronze archaeological objects aged under atmospheric environments using electrochemical impedance spectroscopy (EIS) is described. The method is based on the measurement of resistance associated to the growth of corrosion layers in EIS recorded upon immersion of the pieces in mineral water and applying a bias potential for the reduction of dissolved oxygen. Theoretical expressions for the time variation of such resistance following a potential rate law are presented. Equivalent expressions are derived and applied for estimating the variation of the tenorite/cuprite ratio from their specific voltammetric signals using voltammetry of microparticles data. Calibration curves were constructed from a set of well-documented coins.Financial support from the MEC Projects CTQ2011-28079-CO3-01 and 02 and CTQ2014-53736-C3-2-P which are supported with ERDF funds is gratefully acknowledged.Domenech Carbo, A.; Capelo, S.; Piquero-Cilla, J.; Domenech Carbo, MT.; Barrio, J.; Fuentes, A.; Al Sekhaneh, W. (2016). Dating archaeological copper using electrochemical impedance spectroscopy. Comparison with voltammetry of microparticles dating. Materials and Corrosion. 67(2):120-129. https://doi.org/10.1002/maco.201408048S120129672Friedman, I., & Smith, R. L. (1960). Part I, The Development of the Method. American Antiquity, 25(4), 476-493. doi:10.2307/276634Reich, S., Leitus, G., & Shalev, S. (2003). Measurement of corrosion content of archaeological lead artifacts by their Meissner response in the superconducting state; a new dating method. New Journal of Physics, 5, 99-99. doi:10.1088/1367-2630/5/1/399Scholz, F., Schröder, U., Meyer, S., Brainina, K. Z., Zakhachuk, N. F., Sobolev, N. V., & Kozmenko, O. A. (1995). The electrochemical response of radiation defects of non-conducting materials An electrochemical access to age determinations. Journal of Electroanalytical Chemistry, 385(1), 139-142. doi:10.1016/0022-0728(94)03840-yDoménech-Carbó, A., Labuda, J., & Scholz, F. (2012). Electroanalytical chemistry for the analysis of solids: Characterization and classification (IUPAC Technical Report). Pure and Applied Chemistry, 85(3), 609-631. doi:10.1351/pac-rep-11-11-13Doménech-Carbó, A., Doménech-Carbó, M. T., & Costa, V. (Eds.). (2009). Electrochemical Methods in Archaeometry, Conservation and Restoration. Monographs in Electrochemistry. doi:10.1007/978-3-540-92868-3Doménech-Carbó, A., Doménech-Carbó, M. T., & Peiró-Ronda, M. A. (2011). Dating Archeological Lead Artifacts from Measurement of the Corrosion Content Using the Voltammetry of Microparticles. Analytical Chemistry, 83(14), 5639-5644. doi:10.1021/ac200731qDoménech-Carbó, A., Doménech-Carbó, M. T., Capelo, S., Pasíes, T., & Martínez-Lázaro, I. (2014). Dating Archaeological Copper/Bronze Artifacts by Using the Voltammetry of Microparticles. Angewandte Chemie International Edition, 53(35), 9262-9266. doi:10.1002/anie.201404522Benarie, M., & Lipfert, F. L. (1986). A general corrosion function in terms of atmospheric pollutant concentrations and rain pH. Atmospheric Environment (1967), 20(10), 1947-1958. doi:10.1016/0004-6981(86)90336-7Strandberg, H. (1998). Reactions of copper patina compounds—II. influence of sodium chloride in the presence of some air pollutants. Atmospheric Environment, 32(20), 3521-3526. doi:10.1016/s1352-2310(98)00058-2Cano, E., Lafuente, D., & Bastidas, D. M. (2009). Use of EIS for the evaluation of the protective properties of coatings for metallic cultural heritage: a review. 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Application of the voltammetry of microparticles for dating archaeological lead using polarization curves and electrochemical impedance spectroscopy. Journal of Solid State Electrochemistry, 16(7), 2349-2356. doi:10.1007/s10008-012-1668-9Degrigny, C., Guibert, G., Ramseyer, S., Rapp, G., & Tarchini, A. (2009). Use of E corr vs time plots for the qualitative analysis of metallic elements from scientific and technical objects: the SPAMT Test Project. Journal of Solid State Electrochemistry, 14(3), 425-435. doi:10.1007/s10008-009-0890-6Souissi, N., Bousselmi, L., Khosrof, S., & Triki, E. (2004). Voltammetric behaviour of an archeaological bronze alloy in aqueous chloride media. Materials and Corrosion, 55(4), 284-292. doi:10.1002/maco.200303719Souissi, N., Triki, E., Bousselmi, L., & Khosrof, S. (2006). Comparaison between archaeological and artificially aged bronze interfaces. Materials and Corrosion, 57(10), 794-799. doi:10.1002/maco.200503974Souissi, N., & Triki, E. (2009). Characterization of ethnographic copper corrosion. Materials and Corrosion, 60(4), 262-268. doi:10.1002/maco.200805068Mata, A. L., Salta, M. M. L., Neto, M. M. M., Mendonça, M. H., & Fonseca, I. T. E. (2010). Characterization of two Roman coins from an archaeological site in Portugal. Materials and Corrosion, 61(3), 205-210. doi:10.1002/maco.200905284Feliu, S., Morcillo, M., & Feliu, S. (1993). The prediction of atmospheric corrosion from meteorological and pollution parameters—II. Long-term forecasts. Corrosion Science, 34(3), 415-422. doi:10.1016/0010-938x(93)90113-uSpence, J. W., Haynie, F. H., Lipfert, F. W., Cramer, S. D., & McDonald, L. G. (1992). Atmospheric Corrosion Model for Galvanized Steel Structures. CORROSION, 48(12), 1009-1019. doi:10.5006/1.3315903Bhattacharjee, S., Roy, N., Dey, A. K., & Banerjee, M. K. (1993). Statistical appraisal of the atmospheric corrosion of mild steel. Corrosion Science, 34(4), 573-581. doi:10.1016/0010-938x(93)90273-jKobus, J. (2000). 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Deterministic Modeling of the Corrosion of Low-Carbon Steel by Dissolved Carbon Dioxide and the Effect of Acetic Acid. I-Effect of Carbon Dioxide. doi:10.1149/1.3259806Macdonald, D., & Englehardt, G. (2010). The Point Defect Model for Bi-Layer Passive Films. doi:10.1149/1.3496427Sharifi-Asl, S., Taylor, M. L., Lu, Z., Engelhardt, G. R., Kursten, B., & Macdonald, D. D. (2013). Modeling of the electrochemical impedance spectroscopic behavior of passive iron using a genetic algorithm approach. Electrochimica Acta, 102, 161-173. doi:10.1016/j.electacta.2013.03.143Macdonald, D. D. (2011). The history of the Point Defect Model for the passive state: A brief review of film growth aspects. Electrochimica Acta, 56(4), 1761-1772. doi:10.1016/j.electacta.2010.11.005Doménech-Carbó, A., Lastras, M., Rodríguez, F., Cano, E., Piquero-Cilla, J., & Osete-Cortina, L. (2013). Monitoring stabilizing procedures of archaeological iron using electrochemical impedance spectroscopy. 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Evolution of an iron passive film in a borate buffer solution (pH 8.4). Journal of Solid State Electrochemistry, 15(9), 1927-1934. doi:10.1007/s10008-010-1213-7Park, J.-J., & Pyun, S.-I. (2003). Analysis of impedance spectra of a pitted Inconel alloy 600 electrode in chloride ion-containing thiosulfate solution at temperatures of 298–573 K. Journal of Solid State Electrochemistry, 7(6), 380-388. doi:10.1007/s10008-002-0346-8Ibrahim, M. A., Pongkao, D., & Yoshimura, M. (2001). The electrochemical behavior and characterization of the anodic oxide film formed on titanium in NaOH solutions. Journal of Solid State Electrochemistry, 6(5), 341-350. doi:10.1007/s100080100229Xia, Z., Nanjo, H., Aizawa, T., Kanakubo, M., Fujimura, M., & Onagawa, J. (2007). Growth process of atomically flat anodic films on titanium under potentiostatical electrochemical treatment in H2SO4 solution. 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Characterization of the cardiac ganglion in the crab Neohelice granulata and immunohistochemical evidence of GABA-like extrinsic regulation
The aim of the present work is to provide an anatomical description of the cardiac system in the crab Neohelice granulata and evidence of the presence of GABA by means of immunohistochemistry. The ganglionic trunk was found lying on the inner surface of the heart's dorsal wall. After dissection, this structure appeared as a Y-shaped figure with its major axis perpendicular to the major axis of the heart. Inside the cardiac ganglion, we identified four large neurons of 63.7 μm ± 3.7 in maximum diameter, which were similar to the motor neurons described in other decapods. All the GABA-like immunoreactivity (GABAi) was observed as processes entering mainly the ganglionic trunk and branching in slender varicose fibers, forming a network around the large neurons suggesting that GABAi processes contact them. Our findings strengthen previous results suggesting that the GABAergic system mediates the cardio-inhibitory response upon sensory stimulation.Fil: Yang, Margarita.Fil: Carbo, Martin.Fil: Freudenthal, Ramiro A. M..Fil: Hermitte, Gabriela
Environmental Behaviour of Metolachlor and Diuron in a Tropical Soil in the Central Region of Brazil.
The environmental behaviour of metolachlor and diuron was studied in the Central-western region of Brazil, by means of a field study where six experimental plots were installed. The soil was classified as a Latosol, and the soil horizons were characterized. Sorption of metolachlor and diuron was evaluated in laboratory batch experiments. Metolachlor and diuron were applied to the experimental plots on uncultivated soil in October 2003. From this date to March 2004, the following processes were studied: leaching, runoff and dissipation in top soil. Koc of metolachlor varied from 179 to 264 mL g?1 in the soil horizons. Koc of diuron in the Ap horizon was 917 mL g?1, decreasing significantly in the deeper horizons. Field dissipation half-lives of metolachlor and diuron were 18 and 15 days, respectively. In percolated water, metolachlor was detected in concentrations ranging from 0.02 to 2.84 ?g L?1. In runoff water and sediment, metolachlor was detected in decreasing concentrations throughout the period of study. Losses of 0.02% and 0.54% of the applied amount by leaching and runoff, respectively, were observed confirming the high mobility of this herbicide in the environment. In percolated water, diuron was detected with low frequency but in relatively high concentrations (up to 6.29 ?g L?1). In runoff water and soil, diuron was detected in decreasing concentrations until 70 days after application, totalizing 13.9% during the whole sampling period. These results show the importance of practices to reduce runoff avoiding surface water contamination by these pesticides, particularly diuron
Environmental behaviour of metolachlor and diuron in a tropical soil in the Central Region of Brazil.
The environmental behaviour of metolachlor and diuron was studied in the Central-western region of Brazil, by means of a field study where six experimental plots were installed. The soil was classified as a Latosol, and the soil horizons were characterized. Sorption of metolachlor and diuron was evaluated in laboratory batch experiments. Metolachlor and diuron were applied to the experimental plots on uncultivated soil in October 2003. From this date to March 2004, the following processes were studied: leaching, runoff and dissipation in top soil. K oc of metolachlor varied from 179 to 264 mL g-1 in the soil horizons. K oc of diuron in the Ap horizon was 917 mL g-1, decreasing significantly in the deeper horizons. Field dissipation half-lives of metolachlor and diuron were 18 and 15 days, respectively. In percolated water, metolachlor was detected in concentrations ranging from 0.02 to 2.84 ?g L-1. In runoff water and sediment, metolachlor was detected in decreasing concentrations throughout the period of study. Losses of 0.02% and 0.54% of the applied amount by leaching and runoff, respectively, were observed confirming the high mobility of this herbicide in the environment. In percolated water, diuron was detected with low frequency but in relatively high concentrations (up to 6.29 ?g L-1). In runoff water and soil, diuron was detected in decreasing concentrations until 70 days after application, totalizing 13.9% during the whole sampling period. These results show the importance of practices to reduce runoff avoiding surface water contamination by these pesticides, particularly diuron
Relación óptima de metionina+cistina/lisina digestibles en gallinas isa Brown de 34 a 42 semanas de edad.
Los trabajos previos en los que se han estudiado las recomendaciones de metionina+cistina para gallinas ponedoras son muy numerosos, pero los resultados obtenidos presentan una gran variabilidad y, en algunos casos, son contradictorios. Esta variabilidad se explica por las condiciones en las que se ha realizado el estudio, la edad de las gallinas, la genética y el parámetro a optimizar. En este sentido, Novak et al. (2004) observaron que las necesidades totales de metionina+cistina eran mayores para maximizar el peso del huevo que para optimizar la producción de huevos o la eficacia alimenticia. Estas diferencias fueron menos importantes entre las 20 y 43 semanas (8%), que de las 44 a las 63 semanas de edad (16%). Además, las recomendaciones para optimizar la producción y el peso del huevo fueron un 17% y 11% mayores, respectivamente, en el primer periodo con respecto al segundo. Por el contrario, Waldroup y Hellwig (1995) encontraron que las necesidades totales de metionina+cistina para optimizar la producción y masa de huevo fueron más elevadas (12 y 10%, respectivamente) de 51 a 71 semanas de edad que de 25 a 45. Cuando las recomendaciones se expresan en unidades digestibles, el rango de necesidades de metionina+cistina digestibles con respecto a lisina digestible varía desde un 81 a un 107% (81%: Coon and Zhang, 1999; 90%: FEDNA, 2008; 91%: Rostagno et al., 2005; 93%: CVB, 1996; 94%: Bregendahl et al., 2008; 99%: Brumano et al., 2010a; 100%: Cupertino et al., 2009; Brumano et al., 2010a; 101%: Brumano et al., 2010b; 107%: Schmidt et al., 2009). Como consecuencia de esta alta variabilidad, es necesario seguir investigando sobre cuál sería el ratio óptimo metionina+cistina/lisina digestible para optimizar los rendimientos de gallinas ponedoras. Por tanto, el objetivo de este trabajo es determinar las necesidades óptimas de metionina+cistina digestibles con respecto a lisina digestible de gallinas Isa Brown desde las 34 a las 42 semanas de eda
Novel compound mutations in the mitochondrial translation elongation factor (TSFM) gene cause severe cardiomyopathy with myocardial fibro-adipose replacement
Primary mitochondrial dysfunction is an under-appreciated cause of cardiomyopathy, especially when cardiac symptoms are the unique or prevalent manifestation of disease. Here, we report an unusual presentation of mitochondrial cardiomyopathy, with dilated phenotype and pathologic evidence of biventricular fibro-adipose replacement, in a 33-year old woman who underwent cardiac transplant. Whole exome sequencing revealed two novel compound heterozygous variants in the TSFM gene, coding for the mitochondrial translation elongation factor EF-Ts. This protein participates in the elongation step of mitochondrial translation by binding and stabilizing the translation elongation factor Tu (EF-Tu). Bioinformatics analysis predicted a destabilization of the EF-Ts variants complex with EF-Tu, in agreement with the dramatic steady-state level reduction of both proteins in the clinically affected myocardium, which demonstrated a combined respiratory chain enzyme deficiency. In patient fibroblasts, the decrease of EF-Ts was paralleled by up-regulation of EF-Tu and induction of genes involved in mitochondrial biogenesis, along with increased expression of respiratory chain subunits and normal oxygen consumption rate. Our report extends the current picture of morphologic phenotypes associated with mitochondrial cardiomyopathies and confirms the heart as a main target of TSFM dysfunction. The compensatory response detected in patient fibroblasts might explain the tissue-specific expression of TSFM-associated disease
Los aminoácidos azufrados mejoran la eficacia de utilización del pienso.
Las recomendaciones de metronina+ostina obtenidas a partir de diferentes estudios presentan una gran variabilidad, por lo que es necesario investigar cuál es la relación óptima metronina+ostina /lisina digestible para optimizar los rendimientos de gallinas ponedoras
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