Enhancing the superconducting transition temperature of BaSi2 by structural tuning

We present a joint experimental and theoretical study of the superconducting phase of the layered binary silicide BaSi2. Compared with the layered AlB2 structure of graphite or diboride-like superconductors, in the hexagonal structure of binary silicides the sp3 arrangement of silicon atoms leads to corrugated sheets. Through a high-pressure synthesis procedure we are able to modify the buckling of these sheets, obtaining the enhancement of the superconducting transition temperature from 4 K to 8.7 K when the silicon planes flatten out. By performing ab-initio calculations based on density functional theory we explain how the electronic and phononic properties of the system are strongly affected by changes in the buckling. This mechanism is likely present in other intercalated layered superconductors, opening the way to the tuning of superconductivity through the control of internal structural parameters.Comment: Submitte

Life Span Development: Childhood, Adolescence, and Adulthood

This chapter examines human development in the context of multiple identities. It begins with an exploration of the complexity of human development through the lens of ecological systems theory (Bronfenbrenner, 1977; Bronfenbrenner & Morris, 2006), as augmented by multicultural and feminist psychology (Gilligan, 1982, 1996; Hurtado, 2010; Neville & Mobley, 2001; Yakushko, Davidson, & Williams, 2009). The roles of resilience and empowerment in development are then presented in the context of social identities. The remainder of the chapter explores important developmental concerns across the life span, including physical, emotional, social, and cognitive and academic/vocational development. Across each of these life domains, the specific contributions of feminist multicultural counseling psychology perspectives are identified, with an emphasis on fostering positive development throughout the life span

Noise reduction using wavelet cycle spinning: analysis of useful periodicities in the z-transform domain

Cycle spinning (CS) and a'trous algorithms are different implementations of the undecimated wavelet transform (UWT). Both algorithms can be used for UWT and even though the resulting wavelet coefficients are different, they keep a correspondence. This paper describes an analysis of the CS algorithm performed in the z-transform domain, showing the similarities and differences with the a'trous implementation. CS generates more wavelet coefficients than a'trous, but the number of significative and different coefficients is the same in both cases because of the occurrence of a periodic repetition in CS coefficients. Mathematical expressions for the relationship between CS and a'trous coefficients and for CS coefficient periodicities are provided in the z-transform domain. In some wavelet denoising applications, periodicities (present in the coefficients of the CS procedure) can also be found in the performance measure of the processed signals. In particular, in ultrasonic CS denoising applications, periodicities have been appreciated in the signal-to-noise ratio (SNR) of the ultrasonic denoised signals. These periodicities can be used to optimize the number of CS coefficients for an efficient implementation. Two examples showing the periodicities in the SNR are included. A selection of several reduced sets of CS wavelet coefficients has been utilized in the examples, and the SNRs resulting after denoising are analyzed.This work was partially supported by Spanish MCI Project DPI2011-22438 and MEC Project TIN2013-47272-C2-1-R. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.Rodríguez-Hernández, MA.; San Emeterio, JL. (2016). Noise reduction using wavelet cycle spinning: analysis of useful periodicities in the z-transform domain. Signal, Image and Video Processing. 10(3):519-526. https://doi.org/10.1007/s11760-015-0762-8S519526103Daubechies, I.: Ten Lectures on Wavelets. SIAM, Philadelphia (1992)Mallat, S.: A Wavelet Tour of Signal Processing. Academic Press, New York (1999)Kovacevic, J., Goyal, V.K., Vetterli, M.: Signal Processing Fourier and Wavelet Representations. http://www.fourierandwavelets.org/SPFWR_a3.1_2012.pdf (2012)Burrus, C.S., Gopinath, R.A., Guo, H.: Introduction to Wavelets and Wavelet Transforms. Prentice-Hall, New Jersey (1998)Kamilov, U., Bostan, E., Unser, M.: Wavelet shrinkage with consistent cycle spinning generalizes total variation denoising. IEEE Signal Process. Lett. 19(4), 187–190 (2012)Kumar, B.K.S.: Image denoising based on non-local means filter and its method noise thresholding. Signal Image Video Process. 7, 1211–1227 (2013)Rezazadeh, S., Coulombe, S.: A novel discrete wavelet transform framework for full reference image quality assessment. Signal Image Video Process. 7, 559–573 (2013)Atto, A.M., Pastor, D., Mercier, G.: Wavelet shrinkage: unification of basic thresholding functions and thresholds. Signal Image Video Process. 5, 11–28 (2011)Yektaii, M., Ahmad, M.O., Bhattacharya, P.: A method for preserving the classifiability of digital images after performing a wavelet-based compression. Signal Image Video Process. 8, 169–180 (2014)Kanumuri, T., Dewal, M.L., Anand, R.S.: Progressive medical image coding using binary wavelet transforms. Signal Image Video Process. 8, 883–899 (2014)Kubinyi, M., Kreibich, O., Neuzil, J., Smid, R.: EMAT noise suppression using information fusion in stationary wavelet packets. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 58, 1027–1036 (2011)Abbate, A., Koay, J., Frankel, J., Schroeder, S.C., Das, P.: Signal detection and noise suppression using a wavelet transform signal processor: application to ultrasonic flaw detection. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 44, 14–26 (1997)Pardo, E., San Emeterio, J.L., Rodriguez, M.A., Ramos, A.: Noise reduction in ultrasonic NDT using undecimated wavelet transforms. Ultrasonics 44, e1063–e1067 (2006)Pardo, E., Emeterio, J.L., Rodriguez, M.A., Ramos, A.: Shift invariant wavelet denoising of ultrasonic traces. Acta Acust. United Acust. 94, 685–693 (2008)Shensa, M.J.: The discrete wavelet transform: wedding the a trous and Mallat algorithms. IEEE Trans. Signal Process. 40, 2464–2482 (1992)Coifman, R., Donoho, D.: Translation invariant de-noising. In: Antoniadis, A., Oppenheim, G. (eds.) Wavelets and Statistics, Lecture Notes in Statistics, pp. 125–150. Springer, Berlin (1995)Mallat, S.G.: A theory for multiresolution signal decomposition: the wavelet representation. IEEE Trans. Pattern Anal. Mach. Intell. 2, 674–693 (1989)Beylkin, G., Coifman, R., Rokhlin, V.: Fast wavelet transforms and numerical algorithms. Commun. Pure Appl. Math. 44, 141–183 (1991)Beylkin, G.: On the representation of operators in bases of compactly supported wavelets. SIAM J. Numer. Anal. 6(6), 1716–1740 (1992)Vaidyanathan, P.P.: Multirate Systems and Filter Banks. Prentice Hall, Englewood Cliffs (1992)Donoho, D.L., Johnstone, I.M.: Ideal spatial adaptation by wavelet shrinkage. Biometrika 81, 425–455 (1994)Donoho, D.L., Johnstone, I.M.: Adapting to unknown smoothness via wavelet shrinkage. J. Am. Stat. Assoc. 90, 1200–1224 (1995)Donoho, D.L., Johnstone, I.M., Kerkyacharian, G., Picard, D.: Wavelet shrinkage: Asymptotia? J. R. Stat. Soc. Ser. B 57, 301–369 (1995)Karpur, P., Shankar, P.M., Rose, J.L., Newhouse, V.L.: Split spectrum processing: optimizing the processing parameters using minimization. Ultrasonics 25, 204–208 (1997)Lazaro, J.C., San Emeterio, J.L., Ramos, A., Fernandez, J.L.: Influence of thresholding procedures in ultrasonic grain noise reduction using wavelets. Ultrasonics 40, 263–267 (2002)Donoho, D.L.: De-noising by soft thresholding. IEEE Trans. Inf. Theory 41, 613–627 (1995)Johnstone, I.M., Silverman, B.W.: Wavelet threshold estimators for data with correlated noise. J. R. Stat. Soc. 59, 319–351 (1997

Determinación de vitaminas del Complejo B en Arthrospira maxima por cromatografía líquida de alta resolución

Se diseñan dos métodos para la extracción de las vitaminas del complejo B en muestras de Arthrospira maximacubana. Para la determinación, se emplea un sistema HPLC formado por una columna de octadecilsilano y fasesmóviles de metanol - agua - ácido fosfórico 0.1 mol/L (20:79.5:0.5) para el análisis de la cianocobalamina y (30:69.5:0.5)para el resto de las vitaminas, empleando hexanosulfonato sódico 5 mM en ambos casos. Las velocidades de flujoson de 1 y 0.8 mL/min respectivamente. La determinación se realiza a 362 y 270 nm. Se observó que la Arthrospiramaxima cultivada en Cuba constituye una rica fuente de vitaminas del grupo B presentando un contenido promediode 3.1 mg/10g de tiamina, 4.0 mg/10g de riboflavina, 9.0 mg/10g de piridoxina, 0.29 mg/10g de cianocobalamina, 21mg/10g de ácido nicotínico y 26 mg/10g de nicotinamida

UNA “MIRADA IMPERIAL” A LA HISTORIA CUBA: Our Cuban Colony de Leland Jenks

Há autores foráneos que têm escrito obras sobre Cuba e têm abordado as formas em que os intelectuais cubanos interpretaram o passado da Ilha. No século XX, uma dessas obras foi Our Cuban Colony (1928), de Leland Jenks. Elaborada desde una perspectiva liberal, a mesma brindou uma postura crítica sobre as políticas de Estados Unidos em Cuba. Uma de suas principais críticas girou em torno à dependência de Cuba da produção de açúcar. Assim que esta “mirada imperial” guarda semelhanças importantes com certas visões, sobre todo esquerdistas, acerca da política de Estados Unidos em Cuba.Palavras-chave: Cuba. Imperialismo. Açúcar. Our Cuban Colony ResumenHay autores fo rá neos que han escrito obras sobre Cuba que han incidido sobre las maneras en que los intelectuales cubanos han interpretado el pasado de la Isla. En el siglo XX, una de esas obras fue Our Cuban Colony (1928), de Leland Jenks. Elaborada desde una perspectiva liberal, la misma brindó una postura crítica sobre las políticas de Estados Unidos en Cuba. Una de sus principales críticas giró en torno a la dependencia de Cuba de la producción de azúcar. Así que esta “mirada imperial” guarda semejanzas importantes con ciertas visiones, sobre todo izquierdistas, acerca de la impronta de Estados Unidos em Cuba.Palabras claves: Cuba. Imperialismo. Azúcar. Our Cuban Colony AbstractThere are foreign authors who have written works on Cuba that have impinged the ways in which Cuban intellectuals have interpreted the Island’s past. In the 20th century, Our Cuban Colony, by Leland Jenks, was one of these works. Conceived from a liberal perspective, this book offered a critical view on USA politics in Cuba. One of his main critiques revolved around Cuba’s dependence on sugar. Therefore, this “imperial gaze” is akin to certain ways, especially of the leftist sort, of interpreting the mark of the United States on Cuba.Keywords: Cuba. Imperialism. Sugar. Our Cuban Colon

Spatiotemporal Chaos, Localized Structures and Synchronization in the Vector Complex Ginzburg-Landau Equation

We study the spatiotemporal dynamics, in one and two spatial dimensions, of two complex fields which are the two components of a vector field satisfying a vector form of the complex Ginzburg-Landau equation. We find synchronization and generalized synchronization of the spatiotemporally chaotic dynamics. The two kinds of synchronization can coexist simultaneously in different regions of the space, and they are mediated by localized structures. A quantitative characterization of the degree of synchronization is given in terms of mutual information measures.Comment: 6 pages, using bifchaos.sty (included). 7 figures. Related material, including higher quality figures, could be found at http://www.imedea.uib.es/PhysDept/publicationsDB/date.html . To appear in International Journal of Bifurcation and Chaos (1999