Bloques operacionales como recursos didácticos para resolver problemas en que intervienen razones de cambio

Los bloques operacionales corresponden a las componentes elementales que configuran un modelo matemático, visto este como un modelo simbólico, que representa el planteamiento de una situación problema o la descripción de un fenómeno de la naturaleza. Un bloque operacional implementa una operación matemática de carácter simple o complejo y está determinado por unas variables de entrada, de salida y unos parámetros internos que pueden ser objeto de cambios o ajustes. El cursillo busca integrar los bloques operacionales en el planteamiento y solución de problemas en que aparecen variables relacionadas en el tiempo, esto es, problemas en que intervienen derivadas como razones de cambio. Este propósito se persigue a través de la utilización de la herramienta Simulink de Matlab, vista esta como un recurso computacional que permite el estudio de modelos dinámicos a través del diseño de simuladores interactivos. Las aplicaciones aquí desarrolladas, facilitan la comprensión y descripción por bloques, de las relaciones matemáticas que permiten resolver un problema de aplicación. De igual forma, estas aplicaciones se constituyen en recursos de aprendizaje y contraste de conceptos propios del área de las Ciencias Básicas

Acetaldehyde involvement in ethanol's postabsortive effects during early ontogeny

Clinical and biomedical studies sustains the notion that early ontogeny is a vulnerable window to the impact of alcohol. Experiences with the drug during these stages increase latter disposition to prefer, use or abuse ethanol. This period of enhanced sensitivity to ethanol is accompanied by a high rate of activity in the central catalase system, which metabolizes ethanol in the brain. Acetaldehyde (ACD), the first oxidation product of ethanol, has been found to share many neurobehavioral effects with the drug. Cumulative evidence supports this notion in models employing adults. Nevertheless very few studies have been conducted to analyze the role of ACD in ethanol postabsorptive effects, in newborns or infant rats. In this work we review recent experimental literature that syndicates ACD as a mediator agent of reinforcing aspects of ethanol, during early ontogenetic stages. We also show a meta-analytical correlational approach that proposes how differences in the activity of brain catalase across ontogeny, could be modulating patterns of ethanol consumption.Fil: March, Samanta Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Abate, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Molina, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentin

The role of the electrolyte on the SERS spectra of pyridine

SERS spectra of pyridine has been recorded on a silver electrode in a potential range from 0.0 to -1.20 V with a saline solution, pyridine / KCl (0.1M / 0.1M), by using the 514.5 nm exciting line by us [1]. Under these experimental conditions, the maximum intensity of the enhanced 8a and 9a bands is reached at -0.75 V and -1.20 V, respectively, being the 9a band what dominates the spectrum at negative electrode potential. Although this behavior has been explained under a resonant charge transfer mechanism, the nature of the electronic resonance processes involved in the enhancement of each band is different. The 8a band is enhanced due to an electronic excitation between the ground and excited charge transfer electronic state of the metal-adsorbate surface complex, while the activity of the 9a band is due to a plasmon-like excitation taking into account an overall electronic structure of small metal clusters [2] which is able to selectively modify the relative intensities of specific SERS band. We intend now to record pyridine SERS spectra under the same experimental conditions but varying only the type of electrolyte in order to check how it affects the relative intensities and vibrational wavenumbers of the bands as well as the electrode potential to which the enhanced bands reach the maximum intensity. Different electrolytes like KCl, NaCl, KBr, NaBr and Na2SO4, have been selected in such way that allows us to compare SERS spectra in which changes only the cation or the anion of the electrolyte. From the analysis of all these SERS spectra, it can be concluded that no significant wavenumbers shifts have been detected, while the relative intensities of the bands and the electrode potential to which the maximum intensity is reached are slightly modified. NaBr electrolyte requieres more negative electrode potential in order to enhance the 8a and 9a bands and to resolve the 12 and 1 pair. Acknowledgements We are grateful to the Spanish MINECO (CTQ2012-31846) and Junta de Andalucía (FQM-5156 and 6778), for financial support. References [1] J.F. Arenas, I. López Tocón, J.C. Otero, and J.I. Marcos, J. Phys. Chem. 100, 9254-9261 (1996). [2] J. Román-Pérez, I. López-Tocón, J.L. Castro, J. F. Arenas, J. Soto and J.C. Otero, Phys. Chem. Chem. Phys.17, 2326-2329 (2015).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Las estructuras de comunicación hidráulica en la Vega Alta del Segura (Edad Moderna) y su aporte al turismo

The present study aims to analyze the communication structures of a hydraulic nature (bridges, cradles and boats) during the Modern Age in the Vega Alta del Segura (Region of Murcia). The purpose is to recognize these units for their tourist identity. To reach this con­clusion it has been necessary to examine in detail two lines of topics: the historical and the natural and cultural landscape.Este estudio pretende analizar las estructuras comunicativas de carácter hidráulico (Puen¬tes, cunas y barcos) durante la Edad Moderna en la Vega Alta del Segura (Región de Murcia). La finalidad es reconocer la identidad turística de este patrimonio hidráulico. Con el objeto de llegar a este propósito ha sido necesario examinar con detalle dos líneas de temática: la histórica y el paisaje natural y cultural

FIRM DETERMINANTS IN NEW PRODUCT INTRODUCTION: A STUDY THROUGH SURVIVAL ANALYSIS

The literature has broadly discussed the advantages obtained by pioneer firms under the concept of “first mover advantages”. However, less attention has been paid to the study of the factors that determine entry timing. The present paper analyzes the firm’s determinants in the introduction of a product innovation. The results obtained for the Cox regression in the case of the Italian ceramic tiles industry show that technological resources and firm size have a positive and significant influence on the likelihood of the innovation being introduced, while other factors, i.e. financial and marketing resources, have no influence on the adoption of the innovation.survival analysis, determinants of entry timing, resources, first mover advantages.

Trade credit and credit crunches: Evidence for Spanish firms

Artículo de revist

Copyright literacy and LIS education: analysis of its inclusion in the curricula of master's degree programs

The close relationship between copyright laws and the development of library activities has become more intense and complex in recent years due to the impact of the digital setting. For this reason, librarians must have adequate knowledge about copyright, whether it be to carry out their own functions and tasks, or to help co-workers and users as efficiently as possible. The aim of the present paper is to determine the type of copyright instruction offered, plus its focus and depth, to students of master's programs in library and information studies at today's outstanding universities in this field. The results show that very few LIS programs provide the minimal training required for professionals to be copyright literate. Very few courses are dedicated specifically to copyright issues, as these subjects are usually studied in an excessively generic and superficial manner within broader courses dedicated to information policy, information ethics, or legal issues regarding information. If we also bear in mind that most of these courses are elective, not required, the conclusion is that very few LIS graduates attain the minimal instruction required. The best results are obtained by US and Canadian universities accredited by the American Library Association (ALA), since copyright issues are included in the list of core competences required to achieve accreditation. The solution to this problem may lie in two complementary approaches. One would be to follow the ALA model and the IFLA recommendation and include copyright contents in the LIS curricula worldwide, and the other would be to provide institutional support for those professionals interested in obtaining the required training

Electrochemical SERS spectra of isonicotinic acid analyzed under a photoinduced charge-transfer mechanism

Isonicotinic (IN) acid is one of the three monocarboxilic derivatives of pyridine in which the acid group is located in para-position of the heterocyclic ring. It is a weak acid (pK2=4.86) and therefore, it is not completely ionized in neutral aqueous solutions, being the zwitterion and the anion the majority chemical species at neutral pH. In acidic solutions (pK1=1.84) the pyridinic nitrogen atom can be protonated yielding a third chemical species with positive charge [1]. In addition, IN acid shows two functional centres that can interact with the silver metallic surface such as the carboxilate group and the aromatic nitrogen atom. Therefore, the analysis of the SERS spectra of IN has been focused on identifying the chemical species adsorbed on the silver surface and its centre of interaction by considering the participation of a photoinduced charge-transfer (CT) mechanism in each particular SERS record as we have previously detected in the SERS of pyridine derivatives [2]. SERS spectra of the IN acid (5x10-3 M) have been recorded on silver at electrode potentials ranging from 0.00 up to -1.00 V and at different pH by using 0.1 M Na2SO4 aqueous solution as electrolyte. The figure shows the SERS recorded at basic pH. The experimental set up is described elsewhere and the excitation line of 514.5 nm wavelength was used. [2]. The detection of the presence of CT processes, which are similar to resonance Raman, requires to carry out quantum mechanical calculations [2].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec