Inhomogeneous soliton ratchets under two ac forces

We extend our previous work on soliton ratchet devices [L. Morales-Molina et al., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac forces including non-harmonic drivings, as proposed for particle ratchets by Savele'v et al. [Europhys. Lett. 67}, 179 (2004); Phys. Rev. E {\bf 70} 066109 (2004)]. Current reversals due to the interplay between the phases, frequencies and amplitudes of the harmonics are obtained. An analysis of the effect of the damping coefficient on the dynamics is presented. We show that solitons give rise to non-trivial differences in the phenomenology reported for particle systems that arise from their extended character. A comparison with soliton ratchets in homogeneous systems with biharmonic forces is also presented. This ratchet device may be an ideal candidate for Josephson junction ratchets with intrinsic large damping

Analytical approach to soliton ratchets in asymmetric potentials

We use soliton perturbation theory and collective coordinate ansatz to investigate the mechanism of soliton ratchets in a driven and damped asymmetric double sine-Gordon equation. We show that, at the second order of the perturbation scheme, the soliton internal vibrations can couple {\it effectively}, in presence of damping, to the motion of the center of mass, giving rise to transport. An analytical expression for the mean velocity of the soliton is derived. The results of our analysis confirm the internal mode mechanism of soliton ratchets proposed in [Phys. Rev. E {\bf 65} 025602(R) (2002)].Comment: 9 figures. Submitted to Phys. Rev.

Compositional analysis of InAs-GaAs-GaSb heterostructures by low-loss electron energy loss spectroscopy

As an alternative to Core-Loss Electron Energy Loss Spectroscopy, Low-Loss EELS is suitable for compositional analysis of complex heterostructures, such as the InAs-GaAs-GaSb system, since in this energy range the edges corresponding to these elements are better defined than in Core-Loss. Furthermore, the analysis of the bulk plasmon peak, which is present in this energy range, also provides information about the composition. In this work, compositional information in an InAs-GaAs-GaSb heterostructure has been obtained from Low-Loss EEL spectra

Unified description of the optical phonon modes in NN-layer MoTe2_2

$N$-layer transition metal dichalcogenides provide a unique platform to investigate the evolution of the physical properties between the bulk (three dimensional) and monolayer (quasi two-dimensional) limits. Here, using high-resolution micro-Raman spectroscopy, we report a unified experimental description of the $\Gamma$-point optical phonons in $N$-layer $2H$-molybdenum ditelluride (MoTe$_2$). We observe a series of $N$-dependent low-frequency interlayer shear and breathing modes (below $40~\rm cm^{-1}$, denoted LSM and LBM) and well-defined Davydov splittings of the mid-frequency modes (in the range $100-200~\rm cm^{-1}$, denoted iX and oX), which solely involve displacements of the chalcogen atoms. In contrast, the high-frequency modes (in the range $200-300~\rm cm^{-1}$, denoted iMX and oMX), arising from displacements of both the metal and chalcogen atoms, exhibit considerably reduced splittings. The manifold of phonon modes associated with the in-plane and out-of-plane displacements are quantitatively described by a force constant model, including interactions up to the second nearest neighbor and surface effects as fitting parameters. The splittings for the iX and oX modes observed in $N$-layer crystals are directly correlated to the corresponding bulk Davydov splittings between the $E_{2u}/E_{1g}$ and $B_{1u}/A_{1g}$ modes, respectively, and provide a measurement of the frequencies of the bulk silent $E_{2u}$ and $B_{1u}$ optical phonon modes. Our analysis could readily be generalized to other layered crystals.Comment: Main Text (5 Figures, 2 Tables) + Supporting Information (12 Figures

Factorization of strongly (p,sigma)-continuous multilinear operators

We introduce the new ideal of strongly-continuous linear operators in order to study the adjoints of the -absolutely continuous linear operators. Starting from this ideal we build a new multi-ideal by using the composition method. We prove the corresponding Pietsch domination theorem and we present a representation of this multi-ideal by a tensor norm. A factorization theorem characterizing the corresponding multi-ideal - which is also new for the linear case - is given. When applied to the case of the Cohen strongly -summing operators, this result gives also a new factorization theorem.D. Achour acknowledges with thanks the support of the Ministere de l'Enseignament Superieur et de la Recherche Scientifique (Algeria) under project PNR 8-U28-181. E. Dahia acknowledges with thanks the support of the Ministere de l'Enseignament Superieur et de la Recherche Scientifique (Algeria) [grant number 10/PG-FMI/2013] and the Universite de M'Sila (2013) for short term stage. 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) under project MTM2012-36740-C02-02.Achour, D.; Dahia, E.; Rueda, P.; Sánchez Pérez, EA. (2014). Factorization of strongly (p,sigma)-continuous multilinear operators. Linear and Multilinear Algebra. 62(12):1649-1670. doi:10.1080/03081087.2013.839677S164916706212Matter, U. (1987). Absolutely Continuous Operators and Super-Reflexivity. Mathematische Nachrichten, 130(1), 193-216. doi:10.1002/mana.19871300118Diestel, J., Jarchow, H., & Tonge, A. (1995). Absolutely Summing Operators. doi:10.1017/cbo9780511526138Pietsch, A. (1967). Absolut p-summierende Abbildungen in normierten Räumen. Studia Mathematica, 28(3), 333-353. doi:10.4064/sm-28-3-333-353Achour, D., & Mezrag, L. (2007). On the Cohen strongly p-summing multilinear operators. Journal of Mathematical Analysis and Applications, 327(1), 550-563. doi:10.1016/j.jmaa.2006.04.065Apiola, H. (1976). Duality between spaces ofp-summable sequences, (p, q)-summing operators and characterizations of nuclearity. Mathematische Annalen, 219(1), 53-64. doi:10.1007/bf01360858Sánchez PérezEA. Ideales de operadores absolutamente continuos y normas tensoriales asociadas [PhD Thesis]. Spain: Universidad Politécnica de Valencia; 1997.López Molina, J. A., & Sánchez Pérez, E. A. (2000). On operator ideals related to (p,σ)-absolutely continuous operators. Studia Mathematica, 138(1), 25-40. doi:10.4064/sm-138-1-25-40Cohen, J. S. (1973). Absolutelyp-summing,p-nuclear operators and their conjugates. Mathematische Annalen, 201(3), 177-200. doi:10.1007/bf01427941Mezrag, L., & Saadi, K. (2012). Inclusion and coincidence properties for Cohen strongly summing multilinear operators. Collectanea Mathematica, 64(3), 395-408. doi:10.1007/s13348-012-0071-2Achour, D., & Alouani, A. (2010). On multilinear generalizations of the concept of nuclear operators. Colloquium Mathematicum, 120(1), 85-102. doi:10.4064/cm120-1-7Mujica, X. (2008). τ(p;q)-summing mappings and the domination theorem. Portugaliae Mathematica, 211-226. doi:10.4171/pm/1806Campos, J. R. (2013). Cohen and multiple Cohen strongly summing multilinear operators. Linear and Multilinear Algebra, 62(3), 322-346. doi:10.1080/03081087.2013.779270Bu, Q., & Shi, Z. (2013). On Cohen almost summing multilinear operators. Journal of Mathematical Analysis and Applications, 401(1), 174-181. doi:10.1016/j.jmaa.2012.12.005Ryan, R. A. (2002). Introduction to Tensor Products of Banach Spaces. Springer Monographs in Mathematics. doi:10.1007/978-1-4471-3903-4Achour, D., & Belaib, M. T. (2011). Tensor norms related to the space of Cohen $p$-nuclear‎ ‎multilinear mappings. Annals of Functional Analysis, 2(1), 128-138. doi:10.15352/afa/1399900268Achour, D. (2011). Multilinear extensions of absolutely (p;q;r)-summing operators. Rendiconti del Circolo Matematico di Palermo, 60(3), 337-350. doi:10.1007/s12215-011-0054-2Dahia, E., Achour, D., & Sánchez Pérez, E. A. (2013). Absolutely continuous multilinear operators. Journal of Mathematical Analysis and Applications, 397(1), 205-224. doi:10.1016/j.jmaa.2012.07.034Botelho, G., Pellegrino, D., & Rueda, P. (2007). On Composition Ideals of Multilinear Mappings and Homogeneous Polynomials. Publications of the Research Institute for Mathematical Sciences, 43(4), 1139-1155. doi:10.2977/prims/1201012383Pellegrino, D., Santos, J., & Seoane-Sepúlveda, J. B. (2012). Some techniques on nonlinear analysis and applications. Advances in Mathematics, 229(2), 1235-1265. doi:10.1016/j.aim.2011.09.014Ramanujan, M. S., & Schock, E. (1985). Operator ideals and spaces of bilinear operators. Linear and Multilinear Algebra, 18(4), 307-318. doi:10.1080/03081088508817695Floret, K., & Hunfeld, S. (2002). Proceedings of the American Mathematical Society, 130(05), 1425-1436. doi:10.1090/s0002-9939-01-06228-

Multi-class determination of undesirables in aquaculture samples by gas chromatography/tandem mass spectrometry with atmospheric pressure chemical ionization: A novel approach for polycyclic aromatic hydrocarbons

In this work, a method for the analysis of 24 PAHs in 19 different matrices, including fish tissues, feeds and feed ingredients, has been developed using gas chromatography coupled to triple quadrupole tandem mass spectrometry with atmospheric pressure chemical ionization source (GC-APCI-MS/MS). The method is based on a modification of the unbuffered QuEChERS method, using freezing as an additional clean-up step and applying a 20-fold dilution factor to the final extract. The procedure was also tested for 15 pesticides and 7 polychlorinated biphenyl (PCB) congeners in order to widen the scope of the method. The excellent sensitivity and selectivity provided by GC-APCI-MS/MS allowed the dilution of the sample extracts and quantification using calibration with standards in solvent for all the 19 matrices tested. The developed method was evaluated at 2, 5 and 50 ng·g-1 spiking levels. LOQs were 2 ng·g-1 for most compounds, and LODs ranged from 0.5 to 2 ng·g-1. Analysis of real-world samples revealed the presence of naphthalene, fluorene, phenanthrene, fluoranthene and pyrene at concentration levels ranging from 4.8 to 187 ng·g-1. No PCBs, DDTs and pesticides were found in fillets from salmon and sea bream

Contrast of a Quality Control Model for Sustainability in a Mexican Organization in Central Mexico

Often, the total quality has been instrumented before being weighted. The strategies even precede a diagnosis in Mexican organizations, but in an opposite sense, the present work set out to establish the reliability and validity of an instrument to measure the perception of total quality based on three indicators related to management. , production and transfer of knowledge. A nonperimental study was carried out with a non-probabilistic selection of 124 administrative staff and employees from an organization in central Mexico. From a structural model ⌠X2 = 123,24 (23df) p = 0,010; GFI = 0,990; CFI =,991; IFI = 0,993; RMSEA = 0,007⌡, it was found that management affects production (0,38) and this about the total perceived quality (0,35), although there are lines of research concerning empathy, commitment, entrepreneurship, satisfaction and happiness in relation to the implementation of continuous improvements to the quality of processes and products

Study of protein kinase c signalling in saccharomyces cerevisiae by silac-based phosphoproteomics

Comunicaciones a congreso

Distribuição espaço-temporal das algas marinhas de uma laguna costeira do norte da Península de Yucatán, México

This paper presents the first phycofl oristic study carried out on the coastal lagoon of Chelem, Yucatan, Mexico. Eight sampling sites at three different seasons (dry, rainy and Nortes) allowed us to record 54 taxa of marine algae (35 species of Rhodophyceae, 18 Chlorophyceae and one Phaeophyceae), registered for the first time in this area. Rhodomelaceae is the best represented family, with 19 species. An analysis of PCA of environmental factors and species distribution showed that the Chelem Lagoon may be divided into three zones: inner, middle and outer zones. Temporally, the highest algal diversity (38 spp.) was found in the dry season and the lowest during the “Nortes” (winter) season (28 spp.). Spatially, the highest diversity was found at the outer zone of the lagoon (25 spp.), while the lowest was at the middle zone (13 spp.). The outer zone experiences a major influence of the sea, whereas both the inner and middle zones have brackish waters. The bottom had more species than the mangrove. Jaccard analyses were used to compare sites and seasons and show no similarity between zones and seasons. The distribution pattern in space and time was primarily determined by the salinity because this was the environmental factor that presented the highest variations between zones. The class Rhodophyceae has the largest number of species and dominate over Chlorophyceae and Phaeophyceae in time and space, this is because of the high number of epiphyte algae. Regardless of the distribution and occurrence, the most common species over time was Cladophoropsis macromeres. At least two species [Ceramium brevizonatum var. caraibicum H.E. Petersen and Børgesen and Chondria capillaris (Hudson) M.J. Wynne] represent new records for the State of Yucatan. Key words: marine algae, distribution, seasonality, coastal lagoon, Yucatan Peninsula, Mexico.Este trabalho apresenta o primeiro estudo ficoflorístico efetuado na laguna costeira de Chelem, Yucatán, México. Foram coletadas amostras em oito sítios ao longo da laguna, em três estações do ano (estação de seca, de chuva e “Nortes”). Analisaram-se, espacial e temporalmente, a distribuição das espécies e os fatores ambientais, mediante uma análise dos componentes principais e determinou-se a similitude das estações e das épocas do ano mediante uma análise de conglomerados, usando o índice de Jaccard. Registrou-se um total de 54 espécies (35 da classe Rhodophyceae, 18 Chlorophyceae e uma Phaeophyceae). A família melhor representada foi Rhodomelaceae, com 19 espécies, sendo a maioria epífita. Com base na análise de componentes principais, a laguna foi dividida em três zonas, para fins de estudo: zona interna, zona média e zona externa. A maior riqueza de espécies (38 spp.) foi registrada na época de seca e a menor na época de “Nortes” (28 spp.). Espacialmente, a menor riqueza ocorreu na zona média (com características estuarinas) e a maior na zona externa, que corresponde à zona de desembocadura da laguna junto ao mar. A riqueza de algas foi maior no fundo da laguna que no mangue. O padrão de distribuição espaço-temporal muito provavelmente se deva à salinidade, já que é um dos fatores que apresenta maior variação entre as zonas. Cladophoropsis macromeres ocorreu em todas as épocas e em todas as zonas. Ainda que todas as espécies sejam novos registros para a laguna, duas [Ceramium brevizonatum var. caraibicum H.E. Petersen e Børgesen e Chondria capillaris (Hudson) M.J. Wynne] caracterizam novos registros para o Estado de Yucatán. Palavras-chave: algas marinhas, distribuição, estacionalidade, laguna costeira, Península de Yucatán, México