Exponential stability of a class of boundary control systems

We study a class of partial differential equations (with variable coefficients) on a one dimensional spatial domain with control and observation at the boundary. For this class of systems we provide simple tools to check exponential stability. This class is general enough to include models of flexible structures, traveling waves, heat exchangers, and bioreactors among others. The result is based on the use of a generating function (the energy for physical systems) and an inequality condition at the boundary. Furthermore, based on the port Hamiltonian approach, we give a constructive method to reduce this inequality to a simple matrix inequality

Design of robust controllers for multivariable nonlinear plants

This thesis deals with design techniques for robust non-linear multivariable systems. It describes and discusses some design techniques for such systems. First, one-loop-at-a-time design using the root locus method is considered. The disadvantages of this approach are outlined. Next, some gain-schedulmg controllers are designed for each loop. Then, a multivariable optimization approach is taken. Software to find the frequency domain solution of the two-block weightedmixed- sensitivity problem using the Youla Parameterisation and Smith-McMillan form is developed. This two-variable problem decouples into two single-variable problems, corresponding to optimizing at the input and output of the plant. The fundamental limitations and the trade-offs in design are studied at the input and output of the plant. A11 controllers are tested and implemented on the inverted pendulum-cart apparatus, an unstable single-input two-output system

Editorial : Overcoming challenges in mucosal immunity : 2022

The mucous-producing membranes house the highest concentration of lymphoid tissue in the vertebrate body due to their extensive interaction with the external environment. Although considerable research has been devoted to their study, certain crucial aspects necessitate innovative investigative approaches. Preserving mucosal integrity and regulating immune responses, both locally and systemically, are critical for maintaining homeostasis. This Research Topic addresses fundamental questions about mucosal immunity and its associated challenges. These challenges encompass aspects such as the role of the epithelium in governing both mucosal and systemic immune responses. Contributions to this Research Topic shed light on various topics, for example, the preservation of mucosal barrier integrity, the influence of nutritional elements, namely amino acids, short-chain fatty acid (SCFA) metabolism, and the unfolded protein response (UPR) within intestinal epithelial cells (IEC). Additionally, this Research Topic delves into immunological senescence and its relevance to mucosal immunity, particularly in aging populations.publishedVersio

Poverty, indigence and public investment in Bolivia: A simulation analysis

The study of the impact of public investment on poverty is currently of particular importance due to, among other factors, the commitments that several countries have acquired in the framework of the Millennium Development Goals and the current political situation which gives a more prominent role the government in the economy. We use a general equilibrium model to analyze the impact of public investment on income from various sectors of the economy. Subsequently, we use these results to impute income in the MECOVI 2007 survey. In this way, we calculate various measures of poverty and indigence, and analyze its evolution over time. The estimated measurements indicate that public investment has a positive effect in reducing poverty and indigence in Bolivia, however this effect is small. The most important results are evident in the headcount index that is reduced about 3 points in a scenario of high public investment and 2 points in a scenario like the current investment. However, the results for the poverty gap and severity of poverty and indigence are more modest

Solution structure of ψ(32)-modified anticodon stem–loop of Escherichia coli tRNA(Phe)

Nucleoside base modifications can alter the structures and dynamics of RNA molecules and are important in tRNAs for maintaining translational fidelity and efficiency. The unmodified anticodon stem–loop from Escherichia coli tRNA(Phe) forms a trinucleotide loop in solution, but Mg(2+) and dimethylallyl modification of A(37) N6 destabilize the loop-proximal base pairs and increase the mobility of the loop nucleotides. The anticodon arm has three additional modifications, ψ(32), ψ(39), and A(37) C2-thiomethyl. We have used NMR spectroscopy to investigate the structural and dynamical effects of ψ(32) on the anticodon stem-loop from E.coli tRNA(Phe). The ψ(32) modification does not significantly alter the structure of the anticodon stem–loop relative to the unmodified parent molecule. The stem of the RNA molecule includes base pairs ψ(32)-A(38) and U(33)–A(37) and the base of ψ(32) stacks between U(33) and A(31). The glycosidic bond of ψ(32) is in the anti configuration and is paired with A(38) in a Watson–Crick geometry, unlike residue 32 in most crystal structures of tRNA. The ψ(32) modification increases the melting temperature of the stem by ∼3.5°C, although the ψ(32) and U(33) imino resonances are exchange broadened. The results suggest that ψ(32) functions to preserve the stem integrity in the presence of additional loop modifications or after reorganization of the loop into a translationally functional conformation

La educación literaria y visual a través del libro álbum de tipología narrativa: una plataforma para el destinatario adolescente

[spa] El presente estudio se sitúa en el área de la Didáctica de la Literatura infantil y juvenil cuyo propósito es identificar y analizar las diversas opiniones acerca de las experiencias de lectura con libros álbum por parte de un grupo de estudiantes de enseñanza media de Chile. En ese contexto, el trabajo orienta su estudio desde la perspectiva de la educación literaria y la línea metodológica cualitativa interpretativa junto a una propuesta de categorización. Para la recogida y tratamiento de la información se utilizó la tecnica de focus group y el análisis de los datos cualitativos bajo los rasgos distintivos de la teoría fundamentada. Las concepciones que tienen los estudiantes de enseñanza media, en el marco de los resultados, que se ha podido establecer, tienen relación con que: es posible favorecer el ejercicio lector con la herramienta didáctica de libros álbum a través de las expectativas acerca de su incorporación al repertorio escolar, la incorporación pertinente de un corpus de textos para las lecturas de enseñanza media, la verificación de criterios organizados y justificados para introducir en la clase de lectura reforzando la mirada inferencial, que incluye el aprendizaje con los medios audiovisuales, y que las actuaciones de los estudiantes en el ejercicio lector están mediadas por lo que viven y experimentan, fundamentalmente, en contexto educativo.[eng] The following study focuses on the area of didactics of children and young adult literature, whose objective is to identify and analyze different opinions about the reading experiences using picture books by a group of high school students in Chile. In that context, this work guides its study from the perspective of the literary education and the interpretative qualitative methodological line along with a categorization proposition. For the collecting and treatment of the data, a focus-group technique was used alongside an analysis of qualitative data under the distinctive features of the grounded theory. The high school students’ concepts, according to what have been established by the results, explains that: it is possible to facilitate the reading exercise using didactic tools, such as picture books by the use of the expectations about its incorporation in the school system. The corresponding addition of a set of reading books in the high school syllabus. The verification of organized and justified criteria to be included in reading classes, reinforcing an inferential view, which includes learning using audiovisual means. And, students’ performances in the educational context are mediated, mainly, by what they live and experience

Brick durability and conservation treatment (Santa María de Jesús chapel portal, Seville, Spain)

Se ha estudiado la alteración diferencial de los 2 tipos de ladrillo de la iglesia de Santa María de Jesús (Sevilla) y 2 tratamientos para su restauración. Se han caracterizado por DRX y SEM, así como sus propiedades físicas, hídricas y mecánicas. Probetas preparadas de ladrillos de la iglesia se han sometido a ensayo de cristalización de sales para determinar las causas y los mecanismos de alteración. El ladrillo rojo es el que presenta menor temperatura de cocción, menor porosidad y mayor proporción de microporos. Las propiedades físicas y mecánicas de ambos ladrillos no varían significativamente con los tratamientos, sólo las propiedades hídricas cambian con el hidrófugo. En el ensayo de alteración mejora mucho el comportamiento del ladrillo amarillo, mientras que en el rojo no varía la morfología de alteración (características de materiales con microporos) ni la durabilidadDurability differences of 2 types of brick from Santa María de Jesús Chapel (Sevilla) and 2 treatments for its restoration have been studied. They have been characterizad using XRD and SEM, as well as their physical, hydric and mechanical properties. Samples prepared with bricks from the chapel have been submitted to salt crystallization test, to identify decay causes and mechanisms. The red brick present the lowest firing temperature, lower porosity and a great proportion of micropores. Physical and mechanical properties don’t change significantly with the treatments, only hygric properties vary with the water repellent. The accelerated aging test revealed significant improvement in the behaviour of yellow brick, but no change in the decay mechanism of red brick (Typical of microporous materials) or its durability is observe

Evaluación de la gestión del área de recreación, de la Secretaría Municipal de Recreación y Deportes Pereira respecto al plan de desarrollo en el periodo 2008-2009

En la presente investigación se puede evidenciar uno de los problemas que enfrenta la Secretaria Municipal de Recreación y Deporte, es la ausencia de un método para evaluar los resultados de su gestión, esto se debe a la débil cultura de evaluación que posee y en consecuencia, se dificulta determinar el éxito o fracaso de sus acciones, por esta razón es necesario la realización de esta clase de estudios, clasificando la información y utilizándola como un herramienta para la planeación, en este caso los proyectos que llevó a cabo el Área de Recreación durante los periodos 2008 y 2009, con el fin de mejorar los procesos y tener herramientas para la toma de decisiones, el objetivo general de la investigación es Evaluar la Gestión del Área de Recreación de la Secretaría Municipal de Recreación y Deporte, en el periodo 2008-2009 con respecto al Plan de Desarrollo 2008-2011 "Pereira, Región de Oportunidades" mediante una investigación cuantitativa evaluativa que está orientada a valorar los recursos ejecutados con un indicador como lo es la Eficiencia, y el alcance de las metas representado por la Eficacia; dando aportes significativos como una base de información que permita mantener la historia de la gestión realizada y así mejorar la planeación en los siguientes periodos, siendo más fácil y efectivo, trazando un norte, con la seguridad de estar apuntando al logro de las metas igualmente se realizaron recomendaciones desde el análisis del estudio. Por otro lado y en contraste con los resultados del estudio que positivos en cuanto al grado de gestión alcanzada por el Área de Recreación en el periodo 2008 - 2009 es de anotar que se debe mejorar la claridad en la formulación de los indicadores de resultado, que nos permitirán estudiar el impacto social igualmente mejorar los sistemas de evaluación de los procesos de la actividad administrativa que lleva acabo la Secretaria Municipal de Recreación para obtener los beneficios que esto proporciona y que la investigación sustenta desde la ley, la teoría y la discusión