Riccati nonhermiticity with application to the Morse potential

A supersymmetric one-dimensional matrix procedure similar to relationships of the same type between Dirac and Schrodinger equations in particle physics is described at the general level. By this means we are able to introduce a nonhermitic Hamiltonian having the imaginary part proportional to the solution of a Riccati equation of the Witten type. The procedure is applied to the exactly solvable Morse potential introducing in this way the corresponding nonhermitic Morse problem. A possible application is to molecular diffraction in evanescent waves over nanostructured surfacesComment: 8 pages, 4 figure

Classical harmonic oscillator with Dirac-like parameters and possible applications

We obtain a class of parametric oscillation modes that we call K-modes with damping and absorption that are connected to the classical harmonic oscillator modes through the "supersymmetric" one-dimensional matrix procedure similar to relationships of the same type between Dirac and Schroedinger equations in particle physics. When a single coupling parameter, denoted by K, is used, it characterizes both the damping and the dissipative features of these modes. Generalizations to several K parameters are also possible and lead to analytical results. If the problem is passed to the physical optics (and/or acoustics) context by switching from the oscillator equation to the corresponding Helmholtz equation, one may hope to detect the K-modes as waveguide modes of specially designed waveguides and/or cavitiesComment: 14 pages, 9 figures, revised, accepted at J. Phys.

Evaluando los niveles tróficos de dos tiburones oceánicos del Océano Pacífico suroriental

Indexación: Web of ScienceStable isotope analyses for shortfin mako (Isurus oxyrinchus) and blue sharks (Prionace glauca) were conducted to assess their trophic position in two periods of time (before 1980 and after 2000) in the Southeastern Pacific waters (SEP). Both sharks showed that their trophic position decreased over time (P < 0.05). Many factors could be involved in this change such as dietary shifts, prey availability, or indirect fishing effects in SEP waters.RESUMEN. Para evaluar los niveles tróficos de los tiburones marrajo (Isurus oxyrinchus) y azulejo (Prionace glauca) en dos períodos de tiempo (previo a 1980 y posterior al 2000) en aguas del Pacífico suroriental (SEP), se realizaron análisis de isótopos estables. Ambos tiburones mostraron un descenso del nivel trófico en el tiempo (P < 0,05). Varios son los factores que pueden estar involucrados en este evento, como los cambios dietarios, la disponibilidad de las presas o los efectos indirectos de la pesquería en aguas del Pacífico suroriental.http://www.lajar.cl/pdf/imar/v44n2/Art%C3%ADculo_44_2_25.pd

Reduccionismo: la vigencia de un antiguo problema

El reduccionismo científico, caracterizado como método para entender el todo examinando las partes, ha tenido éxito en ciencia y tecnología. Constituye también una perspectiva que considera a la naturaleza y al universo como determinista, inmutable y no antropocéntrico; ya que intenta reducir los hechos biológicos y mentales a hechos físicos. En este trabajo, intentamos discutir algunas versiones asociadas al reduccionismo ontológico y metodológico, incorporando ejemplos de la Biología y de la Filosofía, con el objeto de discutir sus alcances y limitaciones

Evaluation of an organo-layered double hydroxide and two organic residues as amendments to immobilize metalaxyl enantiomers in soils: A comparative study

Many pollutants released into the environment as a result of human activities are chiral. Pollution control strategies generally consider chiral compounds as if they were achiral and rarely consider enantiomers separately. We compared the performance of three different materials, an organically-modified anionic clay (HT-ELA) and two organic agro-food residues (ALP and ALPc), as amendments to immobilize the chiral fungicide metalaxyl in two soils with different textures, addressing the effects of the amendments on the sorption, persistence, and leaching of each of the two enantiomers of metalaxyl (R-metalaxyl and S-metalaxyl) separately. The effects of the amendments were both soil- and amendment-dependent, as well as enantiomer-selective. The organo-clay (HT-ELA) was much more efficient in increasing the sorption capacity of the soils for the two enantiomers of metalaxyl than the agro-food residues (ALP and ALPc), even when applied at a reduced application rate. The enhanced sorption in HT-ELA-amended soils reduced the bioavailability of metalaxyl enantiomers and their leaching in the soils, mitigating the particularly high leaching potential of the more persistent S enantiomer. The immobilizing capacity of the agro-food residues was more variable, mainly because their addition did not greatly ameliorate the sorption capacity of the soils and had variable effects on the enantiomers degradation rates. HT-ELA showed potential to reduce the bioavailability and mobility of metalaxyl enantiomers in soil and to mitigate the contamination problems particularly associated with the higher leaching potential of the more persistent enantiomer. 11 páginas.-- 5 figuras.-- 2 tablas.-- referencias.-- Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jenvman.2016.06.019This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Projects AGL2011-23779 and AGL2014-51897-R) and Junta de Andalucía (JA Research Group AGR-264), co-financed with FEDER-FSE funds. The authors thank B. Gamiz for her help in the design of the experiments and L. Cox for kindly supplying the organic residues. R. Lopez-Cabeza also thanks MINECO for a pre-doctoral fellowship linked to the Project AGL2011-23779 (Grant BES-2012-059945)Peer Reviewe

Textural properties of synthetic clay-ferrihydrite associations

13 páginas, 8 figuras, 3 tablas, 35 referencias.Kaolinite-ferrihydrite and montmorillonite-ferrihydrite associations were prepared following a procedure based on the Russell method for the synthesis of ferrihydrite and the texture of the clay-ferrihydrite complexes was studied using different techniques. The textural properties of kaolinite were little affected by the Fe association, showing only a slight .increase in the specific surface area measured by nitrogen adsorption and a decrease in the largest pores (>10 micro m), as measured by mercury porosimetry. In contrast, the nitrogen specific surface area of the montmorillonite complexes was much higher than that of the clay without Fe and the pore structure depended on the amounts of Fe in the complexes. Application of the fractal approach to nitrogen adsorption data indicated that the surface roughness (microporosity) was greater for the complexes prepared from diluted Fe(III) solutions, in agreement with the information obtained from classical interpretation of the adsorption isotherms (shape of the isotherms and t-plots).This study has been supported partially by the CICYT through the project AMB-93-81 , AMB-96-445-C02- 02, the EU project EV 5V-CT94-0470, and by the Research Group RNM 124 of Junta de Andalucía. R. Celis also thanks the Spanish Ministry of Education and Science for his PFPU fellowship.Peer reviewe

Una fiesta y varias fronteras: los Quintos de Barrancos (Portugal) y Noblejas (España)

En este artículo intentamos ensayar una perspectiva comparativa sobre la fiesta de los quintos en dos municipios distintos, uno en España y otro en Portugal. Para ello analizamos en primer lugar las formas en que se desarrolla la fiesta en ambos casos, señalando las coincidencias y diferencias que existen en la propia celebración. A partir de aquí se desarrolla el análisis comparativo, para el que se introduce una doble perspectiva: el pueblo y la villa como escenarios de la convivencia, y la fiesta como frontera en un sentido espacial y también temporal. Por último, se exponen algunas conclusiones sobre lo que se revela en la comparación

Cambio Global: perspectiva ético-epistemológica

En el marco del cambio global entendido como un conjunto de componentes interactuantes que alteran la estructura y, función de la tierra como sistema, existe una jerarquía de problemas ambientales que ejercen influencia a nivel planetario, regional y local. A nivel global estamos hablando del aumento en las concentraciones de nutrientes en los océanos y del cambio climático (incremento de las concentraciones atmosféricas de. C02, CH., N02, CFC). A niveles locales nos enfrentamos con la pérdida de biodiversidad, la fragmentación del ambiente, escasez de agua, desertificación, por citar algunos

Representaciones subyacentes de un mundo insustentable

La relación entre la humanidad y la crisis ambiental, se encuentra en un punto de inflexión, con problemas que se manifiestan en los niveles local, regional y global. Cuando se piensa en el futuro, existe una tendencia a extrapolar linealmente lo que viene sucediendo; sin embargo, son numerosos los casos en los que las .situaciones futuras no son necesariamente una continuación de lo que venía ocurriendo. Existen virajes, reacciones desproporcionadas, colapsos y discontinuidades en los sistemas naturales y sociales en respuesta a muchas de las actividades humanas a las que son sometidos

Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter

A supersymmetric class of free damped oscillators with three parameters has been obtained in 1998 by Rosu and Reyes through the factorization of the Newton equation. The supplementary parameter is the integration constant of the general Riccati solution. The estimation of the latter parameter is performed here by employing the recent adaptive observer scheme of Besancon et al., but applied in a nonstandard form in which a time-varying quantity containing the unknown Riccati parameter is estimated first. Results of computer simulations are presented to illustrate the good feasibility of this approach for a case in which the estimation is not easily accomplished by other meansComment: 8 pages, 6 figure