Efficient Calculation of the Green's Functions for Multilayered Shielded Cavities with Right Isosceles-Triangular Cross-Section

An efficient calculation of the Green’s functions inside multilayered shielded cavities with right isosceles-triangular cross-section is presented. The method is entirely developed in the spatial domain, and it is based on image theory. The idea is to use the spatial-domain Green’s functions inside a multilayered shielded square box, in order to accurately obtain the Green’s functions for the right isosceles-triangular cavity. Image theory is then used to enforce the boundary conditions along the non-equal side of the triangle. It is shown that the new algorithm is very robust, with limited computational effort. Resonance frequencies and potential patterns of a triangular cavity have been calculated and compared with those obtained by other techniques, showing very good agreement. Finally, a transversal filter inside a multilayered triangular-shaped cavity is designed, manufactured and tested using the developed technique.This work was partially supported by the Spanish Ministry of Education and Science under Grant FPU-AP2006-015 and with the Project TEC2007-67630-C03-02

Estado actual del concepto de simetría en los estudiantes del grado décimo de las instituciones educativas de florencia caquetá

La licenciatura en matemáticas y física desarrolla los espacios académicos estadística y probabilidades (matemáticas escolares) y problemas de la aleatoriedad (problema de aula) durante el sexto semestre. Para lograr la integridad de estos espacios académicos los estudiantes indagaron sobre el concepto de simetría (asimetría) en estadística. La investigación se realizó en las instituciones educativas San Francisco de Asís, Técnico Industrial y La Salle, de Florencia (Caquetá); el grupo focal (muestra) lo conformaron 81 estudiantes, los cuales realizaron un test acerca del tema, que permitiera determinar las falencias que tienen los estudiantes en dichos conceptos. Se resalta el hecho dentro de los resultados que los estudiantes a pesar de contextualizar no estructuran definiciones, conllevando a la falta de comprensión y análisis de situaciones formales

Design of Dual-Bandpass Hybrid Waveguide-Microstrip Microwave Filters

A simple dual-bandpass filtering structure is pro- posed. The filter is implemented by means of a new hybrid waveguide­microstrip technology. The novelty of the structure is that it combines two standard printed microstrip coupled line resonators, with a resonance of the base waveguide cavity, to implement a dual-band operation. Important aspects about the filter design, useful for practical applications are treated. This includes a study on the maximum coupling that can be achieved to the cavity resonance, and guidelines to control the positions of the two passbands and the transmission zeros. Besides, an example has been designed, manufactured and tested. The measurements on the fabricated prototype have confirmed the validity of the new structure to perform dual-band operation.Ministerio de Educación y Ciencia, Ref. TEC2007-67630-C03-0

Adaptation of Afro Colombian students to an intercultural context in universities in Bogotá

From color of skin and ways of speaking to interculturality backgrounds, minorities as Colombian afro descendants are still suffering because of discriminatory issues, especially in universities in Bogotá, where higher education is addressed towards globalization. These types of violations affect the development of Colombian afros in the education arena, they sometimes experience isolation and episodes of discrimination in the study hall, promoting social inequity and injustice. In this context, afro descendants need to include the adaptation to the social requirements present in the capital city in order to achieve individual projects. Nevertheless, society manifest acts of discrimination in the lecture room, and in different spheres of human relations and interactions affecting the processes for proper advance in the generation of elements for successful communication. Yet, afro students adapt to academic atmospheres by integrating and assuming roles proper of that environment.ADAPTATION OF AFRO COLOMBIAN STUDENTS TO INTERCULTURAL CONTEXTS IN UNIVERSITIES IN BOGOTÁ Introduction Statement of the problem Interculturality for Communication Racism and Discrimination in the Study Hall Interculturality Manifestations towards Afro Descendants in the Study Hall CONCLUSIONS REFERENCES APPENDIXPregradoProfesional en Lenguas ModernasLenguas Moderna

An interpolated spatial images method for the analysis of multilayered shielded microwave circuits

In this paper, an efficient interpolation method is presented in order to compute the Green’s function associated to electrical sources, when they are placed inside cylindrical cavities. The interpolation scheme is formulated in the frame of the spatial images technique recently developed. The original idea was to calculate, for every location of a point electric source, the complex values of the electric dipole and charge images, placed outside the cavity, to impose the appropriate boundary conditions for the potentials. In order to considerably reduce the computational cost of the original technique, a simple interpolation method is proposed to obtain the complex values of the images for any source location. To do that, a rectangular spatial subdivision inside the cavity is proposed. Each new sub-region is controlled by means of the exact images values obtained when the source is placed at the four corners of the region. The key idea is to use a bilinear interpolation to obtain the images complex values when the source is located anywhere inside this sub-region. The interpolated images provide the Green’s functions of the new source positions fast, and with high accuracy. This new approach can be directly applied to analyze printed planar filters. Two examples with CPU time comparisons are provided, showing the high accuracy and computational gain achieved with the technique just derived.This work was partially supported by the Spanish Ministry of Education and Science under Grant FPU-AP2006-015 and with the Project TEC2007-67630-C03-02

A Systematic Algorithm for the Design of Hybrid Waveguide-Microstrip Transversal Microwave Filters

A novel algorithm to design hybrid waveguide-microstrip transversal microwave filters is proposed in this study. The idea consists in isolating each resonator involved in the filter structure, to synthesise individually its frequency response, both in resonant frequency and bandwidth. These separated optimisations lead to the dimensions of the filtering structure to meet the requirements of a certain, specified transfer function. The novel algorithm introduces an iterative procedure in order to synthesise the direct coupling term between source and load, which is always present in the hybrid filter structure. The whole algorithm is illustrated by means of a design example, where a very good agreement between the ideal specified transfer function and the final frequency response of the designed hybrid filter is obtained. A second different design example, which has been manufactured and tested, is also included for validation.Ministerio de Educación y Ciencia, Ref. TEC2010-21520-C04-0

Novel implementations for microstrip resonator filters in transversal topology

This paper presents novel implementations of bandpass filters in multilayered microstrip technology. The structures presented implement transversal filter topologies of order three. In order to allow for easy implementation of the required couplings, multilayered broadside configurations are proposed. We demonstrate that with the proposed configurations, both dualband and quasi-elliptic responses can be easily synthesized, by only changing the sign of certain entries in the coupling matrix. To easily adjust the signs of the couplings, novel resonators are proposed, including simple half-wavelength transmission line resonators, meander line resonators and short-circuited resonators. Experimental validation for one prototype is presented, demonstrating the validity and usefulness of the proposed configurations.The authors thank Ministerio de Educación y Ciencia of Spain, which has supported this work under Grant TEC2007- 67630-C03/TCM

Design considerations of a randomized clinical trial on a cognitive behavioural intervention using communication and information technologies for managing chronic low back pain

Background: Psychological treatments have been successful in treating chronic low back pain (CLBP). However, the effect sizes are still modest and there is room for improvement. A way to progress is by enhancing treatment adherence and self-management using information and communication technologies (ICTs). Therefore, the objective of this study was to design a trial investigating the short- and long-term efficacy of cognitive behavioural treatment (CBT) for CLBP using or not ICTs. A secondary objective of this trial will be to evaluate the influence of relevant variables on treatment response. Possible barriers in the implementation of CBT with and without ICT will also be investigated. Methods: A randomised controlled trial with 180 CLBP patients recruited from specialised care will be conducted. Participants will be randomly assigned to three conditions: Control group (CG), CBT, and CBT supported by ICTs (CBT + ICT). Participants belonging to the three conditions will receive a conventional rehabilitation program (back school). The CBT group program will last six sessions. The CBT + ICT group will use the internet and SMS to practice the therapeutic strategies between sessions and in the follow-ups at their homes. Primary outcome variables will be self-reported disability and pain intensity. Assessment will be carried out by blinded assessors in five moments: pretreatment, post-treatment and 3-, 6-, and 12-month follow-ups. The influence of catastrophizing, fear-avoidance beliefs, anxiety and depression in response to treatment in the primary outcomes will also be analysed. Discussion: This study will show data of the possible benefits of using ICTs in the improvement of CBT for treating CLBP