377 research outputs found
Contributions to mathematical modelling and numerical simulation of biofilms
Programa Oficial de Doutoramento en Métodos Matemáticos e Simulación Numérica en Enxeñaría e Ciencias Aplicadas. 551V01[Abstract]The main goal of this PhD work is the development and numerical resolution of
mathematical models that simulate the dynamics of bacterial biofilm systems, paying
special attention to those biofilms formed by the Listeria monocytogenes, a pathogen
of special relevance in food safety.
A biofihn is a layer of microorganisms attached to a surface and protected by a
matrix of exopolysaccharides. Biofilm structures difficult the removal of microorganisms,
thus the study of the type of structures formed throughout a biofilm life cycle
is key to design elimination techniques.
In the present work, we develop different models that simulate the dynamics of
biofilms formed by different strains of L. monocytogenes. We start with a 1D model
that can be used to describe the formation of flat biofilms. Afterwards, we apply
the acquired knowledge to develop a 2D model capable of describing more complex
structures. All this models are solved with efficient numerical methods and robust
numerical techniques, such as the Level Set method, that guarantees the good behaviour
of the obtained solutions. Finally, the numerical results are compared with the experimental measurements
obtained in the Instituto de Investigaciones Marinas, CSIC (Vigo, Spain), and the
Micalis Institute, INRA (Massy, France).[Resumen]El objetivo fundamental de esta tesis consiste en el desarrollo y resolución numérica
de modelos matemáticos que reproduzcan la dinámica de biopelículas, en especial,
aquellas formadas por Listeria monocytogenes, un patógeno especialmente relevante
en la seguridad alimentaria.
Una biopelícula es una capa de microorganismos adheridos a una superficie y protegidos
por una matriz de expolisacáridos. La estructura de las biopelículas hace
difícil la eliminación de los microorganismos, de ahí que sea fillldamental estudiar
el tipo de estructuras que se forman durante la vida de una biopelícula para poder
diseñar nuevas técnicas de eliminación.
En el presente trabajo, desarrollamos modelos que simulan la dinámica de biopelículas
de diferentes cepas de L. monocytogenes. Comenzamos estableciendo un modelo
1D capaz de describir la formación de biopelículas planas para, posteriormente,
aplicar los conocimientos adquiridos al desarrollo de un modelo 2D capaz de describir
estructuras más complejas. Estos modelos se resuelven con métodos numéricos eficientes
y técnicas numéricas robustas, como el método Level Set, que garantizan el
buen comportamiento de las soluciones.
Finalmente, los resultados obtenidos son comparados con las imágenes de microscopía
procedentes de experimentos realizados en el Instituto de Investigaciones
Marinas, CSIC (Vigo, España) yen el Micalis Institute, INRA (Massy, Francia).[Resumo ] O obxectivo fundamental desta tese é o desenvolvemento e resolución numérica de
modelos matemáticos que reproduzan a dinámica de biopelículas, en especial, aquelas
formadas por Lisieria monocytogenes, un patóxeno de especial relevancia na seguridade
alimentaria.
Unha biopelícula é unha capa de microorganismos adheridos a unha superficie
e protexidos por unha matriz de expolisacáridos. A estructura das biopelículas fai
difícil a eliminación dos microorganismos, de aí que sexa fundamental estudar o tipo
de estructuras que se forman ao longo da vida dunha biopelícula para poder deseñar
novas técnicas de eliminación.
No presente traballo, desenvolvemos modelos que simulan a evolución de diferentes
cepas de L. monocytogenes. Comezamos establecendo un modelo 1D capaz
de describir a dinámica de cepas chás para, posteriormente, aplicar os coñecementos
adquiridos ao desenvolvemento dun modelo 2D capaz de describir estruturas máis
complexas. Todos estes modelos resólvense con métodos numéricos eficientes e técnicas
numéricas robustas, como o método Level Set, que garanten o bo comportamento das
solucións.
Finalnlente, os resultados obtidos compáranse coas imáxes de microscopía obtidas
en experimentos realizados no Instituto de Investigacions Mariñas, CSIC (Vigo,
España) e no Micalis Institute, INRA (Massy, Francia)
A Two-Dimensional Multi-Species Model for Different Listeria Monocytogenes Biofilm Structures and Its Numerical Simulation
[Abstract] In this work we propose a two-dimensional multi-species model to describe the dynamics of biofilms formed by the pathogenic bacteria Listeria monocytogenes. Different Listeria monocytogenes strains produce biofilms with different structures, namely flat, honeycomb and clustered. Previous works showed that glucose impaired uptake and the appearance of damaged or dead cells are critical mechanisms underlying Listeria monocytogenes biofilm dynamics. Here we explicitly propose an extension of the two-dimensional multi-species model proposed by Alpkist and Klapper to account for those mechanisms. The result is a continuous two-dimensional multi-species model with non-linear detachment and mass action nutrient consumption. Moreover, we also propose a set of efficient numerical methods to solve the coupled model and we have developed their computer implementation from scratch in C/C++. Mainly based on finite differences schemes, these numerical techniques include Crank-Nicolson schemes for time discretization, Gibou’s ghost node techniques and level set methods to cope with the free boundary associated to the determination of the time-dependent biofilm domain. To finish with, we compare our simulation results with the dynamics of real biofilms as observed in the laboratory. More precisely, by using model parameters calibrated to experiments, the numerical results clearly illustrate the performance of the proposed model and the numerical methods to reproduce the real dynamics of flat, clustered and honeycomb structures shown by different Listeria monocytogenes strains.ALN and CV acknowledge the funding by MINECO from Spanish Government (Grant MTM2016-76497-R) and by Xunta de Galicia (Grants GRC2014/044 and ED431C2018/033). ALN acknowledges FPU fellowship (FPU13/02191) from the Spanish Government program MECD-FPU. CV and ALN as members of CITIC also akcnowledge the grant ED431G 2019/01, funded by Consellería de Educación, Universidade e Formación Profesional of Xunta de Galicia through FEDER funds with 80%, from FEDER Galicia 2014-2020 Program and 20% from Secretaría Xeral de Universidades. EBC acknowledges funding from Contrato Programa and grant Ref. IN607B 2017/02 from Xunta de Galicia. All grants include FEDER fundsXunta de Galicia; GRC2014/044Xunta de Galicia; ED431C2018/033Xunta de Galicia; ED431G 2019/01Xunta de Galicia; IN607B 2017/0
Elaboración de carpeta técnica para la intervención del Paseo Santa Catarina, Apopa
Como parte de la labor social y en la búsqueda de mejorar la calidad de vida de las personas se elaboró la carpeta técnica con el asesoramiento técnico de INDIGO estudio para la intervención del Paseo Santa Catarina en el municipio de Apopa que sirva como un instrumento integral que brinde a la municipalidad y terceros las herramientas para su ejecució
A novel growth method to improve the quality of GaAs nanowires grown by Ga-assisted chemical beam epitaxy
The successful synthesis of high crystalline quality and high aspect ratio GaAs nanowires (NWs) with a uniform diameter is needed to develop advanced applications beyond the limits established by thin film and bulk material properties. Vertically aligned GaAs NWs have been extensively grown by Ga-assisted vapor–liquid–solid (VLS) mechanism on Si(111) substrates, and they have been used as building blocks in photovoltaics, optoelectronics, electronics, and so forth. However, the nucleation of parasitic species such as traces and nanocrystals on the Si substrate surface during the NW growth could affect significantly the controlled nucleation of those NWs, and therefore the resulting performance of NW-based devices. Preventing the nucleation of parasitic species on the Si substrate is a matter of interest, because they could act as traps for gaseous precursors and/or chemical elements during VLS growth, drastically reducing the maximum length of grown NWs, affecting their morphology and structure, and reducing the NW density along the Si substrate surface. This work presents a novel and easy to develop growth method (i.e., without using advanced nanolithography techniques) to prevent the nucleation of parasitic species, while preserving the quality of GaAs NWs even for long duration growths. GaAs NWs are grown by Ga-assisted chemical beam epitaxy on oxidized Si(111) substrates using triethylgallium and tertiarybutylarsine precursors by a two-step-based growth method presented here; this method includes a growth interruption for an oxidation on air between both steps of growth, reducing the nucleation of parasitic crystals on the thicker SiOx capping layer during the second and longer growth step. VLS conditions are preserved overtime, resulting in a stable NW growth rate of around 6 μm/h for growth times up to 1 h. Resulting GaAs NWs have a high aspect ratio of 85 and average radius of 35 nm. We also report on the existence of characteristic reflection high-energy electron diffraction patterns associated with the epitaxial growth of GaAs NWs on Si(111) substrates, which have been analyzed and compared to the morphological characterization of GaAs NWs grown for different times under different conditions
Gestión para el cambio de la cultura docente a partir del proceso de la planeación didáctica
El presente trabajo es una propuesta de gestión que busca favorecer el cambio de cultura en la función docente, específicamente en relación a la planeación didáctica. El proyecto se orientó a fortalecer el desempeño docente a través de un proceso personal y colaborativo de trabajo colegiado entre los miembros del equipo docente de la institución donde se elaboró. La metodología empleada fue la de intervención educativa, la cual nos permitió reconocer al sujeto en relación con el contexto y la dinámica de la interacción social, de tal modo que desde la perspectiva de la gestión, responda a las necesidades específicas del centro educativo
Stress-assisted atomic diffusion in metastable austenite D03 phase of Cu-Al-Be shape memory alloys
Cu-Al-based shape memory alloys are firm candidates to be used up to 473 K. The main limiting aspect is the activation of diffusion processes in the metastable austenite phase, which drive the alloy decomposition. In the present work the study of short-distance diffusion processes has been approached by internal friction. A relaxation peak has been found in the metastable beta (D0(3)) phase of a Cu-Al-Be shape memory alloy, around 500 K (at 1 Hz), with an activation energy of E-a = 138 +/- 0.05 eV. An atomic mechanism of elastic dipoles Antisite-Vacancy reorientation, involving stress-assisted short distance Cu-atoms diffusion, has been proposed. (C) 2016 Elsevier B.V.This work was supported by the European H2020 Project REACT, Grant No 640241, and the Spanish Ministry MINECO projects, MAT2012-36421 and CONSOLIDER-INGENIO 2010 CSD2009-00013, as well as by the Consolidated Research Group IT-1090-16 from the Education Department and the project ELKARTEK ACTIMAT, KK-2015/0000094, from the Industry Department of the Basque Government
Prescripción de las acciones monitorias y los procesos ordinarios para el cobro de las obligaciones
Introduction: The topic to be investigated is part of the need to know the legal vacuum that exists of the prescription time to collect the obligation by order for payment procedure. These procedures grant the actor the power to exercise the collection action for a monetary, liquid debt, demandable and expired, as stated in article 356 of the COGEP whenever it does not exceed fifty Unified Basic Salaries. Objective: The objective of this investigation has been to analyze the collection of obligations through payment order procedure to establish the need to correct the legal vacuum that exists regarding the prescription time of these. Methodology: The research is part of a systematic method, as well as the analytical - synthetic and deductive - inductive, the approach used is the qualitative one. Thus, an academic work of a historical descriptive and review documentary type has also been prepared. Results: The evidence that proves a previous relationship between creditor and debtor was analyzed when the document -which is intended to be collected- has been created unilaterally by the creditor. Conclusions: Regarding the collection action, COGEP does not establish any time for the prescription, thus generating a structural vacuum that is unavoidable to correct.Introducción: La temática a investigar se enmarca en las necesidades de saber el vacío legal que existe del tiempo de prescripción para cobrar la obligación por procedimiento monitorio, Estos procedimientos otorga al actor la facultad de ejercer la acción de cobro por una deuda dineraria, líquida, exigible y vencida, como consta en el artículo 356 del COGEP toda vez que no exceda de cincuenta Salarios Básicos Unificados. Objetivo: El objetivo de la presente investigación ha sido analizar el cobro de obligaciones a través de procedimiento monitorio a fin de establecer la necesidad de subsanar el vacío legal que existe respecto del tiempo de prescripción de estas. Metodología: La investigación se enmarca en un método sistemático, así como el analítico - sintético y deductivo – inductivo, el enfoque empleado es el cualitativo. Así también se ha elaborado un trabajo académico de tipo documental histórico descriptivo y de revisión. Resultados: Se analizó la prueba que acredita una relación previa entre acreedor y deudor, cuando el documento -que se pretende cobrar- haya sido creado unilateralmente por el acreedor. Conclusiones: Sobre la acción de cobro, el COGEP no estatuye tiempo alguno para la prescripción generando así un vacío estructural que resulta ineludible subsanar. Área de estudio general: Jurisprudencia y Ciencias Sociales. Área de estudio específica: Derecho civil
Neurophysiological pain education for patients with symptomatic knee osteoarthritis: A systematic review and meta-analysis
Objective
To evaluate the effectiveness of neurophysiological pain education in patients with symptomatic knee osteoarthritis considering pain-related variables.
Methods
A systematic review and meta-analysis was carried out according to the PRISMA guidelines. A search was conducted in PubMed, PEDro Database, Cochrane Library, Scopus, and Web of Science. Only randomized controlled trials enrolling patients ≥ 18 years of age with symptomatic knee osteoarthritis were included. The Downs and Black quality assessment tool was used to assess the quality of the articles, and the risk of bias was evaluated with the Cochrane Risk of Bias Assessment Tool.
Results
A total of 7 studies were included in the study. Most of the studies were rated as “fair” on the Downs and Black quality assessment tool, and in the category of “some concerns” according to the Cochrane Risk of Bias Assessment Tool. Neurophysiological pain education was conducted alone or combined with exercise, joint mobilizations, or self-management programs. The number of sessions ranged from 1 to 10. The meta-analysis results showed significant differences in favor of the intervention group in pain (MD = −0.49; 95% CI = −0.66; −0.32; p < 0.001) and catastrophization (MD = −1.81; 95% CI = −3.31, −0.3; p = 0.02).
Conclusion, practice implications
Neurophysiological pain education interventions in isolation or combined with exercise, joint mobilizations, or self-management programs have proven to significantly improve pain and catastrophization in patients with symptomatic knee osteoarthritis. These findings could provide clinicians with more information regarding the management of patients with symptomatic knee osteoarthritis.Spanish Ministry of Education through a grant for the training of uni-
versity faculty (code FPU:19/02609,FPU: 20/01670 and FPU: 21/
00451, respectively)
Role of breathing training programs on quality of life in chronic kidney disease patients
Background: Due to its chronic and progressive nature, chronic kidney disease (CKD) affects patients in many spheres including their perception of quality of life (QOL). Breathing training techniques have shown positive effects on health and QOL for different conditions. Objective: The aim of this study was to perform a scoping review to examine the characteristics related to the application of breathing training on patients with CKD, and to identify the relevant outcomes and target group for the application of breathing training. Methods: This scoping review was performed in accordance with PRISMA-SRc guidelines. We systematically searched three electronic databases for articles published before March 2022. The studies included patients with chronic kidney disease that received breathing training programs. The breathing training programs were compared to usual care or no treatment. Results: A total of four studies were included in this scoping review. The four studies had heterogeneous disease stages and breathing training programs. All the studies included reported positive effects of breathing training programs on QOL of CKD patients. Conclusion: The breathing training programs were able to improve the quality of life of patients with CKD undergoing hemodialysis treatment.Spanish Ministry of Education [grant number FPU: 20/0167
Post-COVID Patients With New-Onset Chronic Pain 2 Years After Infection: Cross-Sectional Study
Background: Although pain is common in non-hospitalized post-COVID-19 syndrome, only a few studies
have provided information on the pain experience of these patients.
Aim: To identify the clinical and psychosocial profile associated with pain in non-hospitalized patients
with post-COVID-19 syndrome.
Method: In this study there were three groups: healthy control group, successfully recovered group, and
post-COVID syndrome group. Pain-related clinical profile and pain-related psychosocial variables were
collected. Pain-related clinical profile included: pain intensity and interference (Brief Pain Inventory),
central sensitization (Central Sensitization Scale), insomnia severity (Insomnia Severity Index), and pain
treatment. Pain-related psychosocial variables were: fear of movement and (re)injury (Tampa Scale for
Kinesiophobia), catastrophizing (Pain Catastrophizing Scale), depression, anxiety and stress (Depression,
Anxiety and Stress Scale), and fear-avoidance beliefs (Fear Avoidance Beliefs Questionnaire).
Results: In all, 170 participants were included in the study (healthy control group n = 58, successfully
recovered group n = 57, and post-COVID syndrome group n = 55). Post-COVID syndrome group obtained
significantly worse punctuation in pain-related clinical profile and psychosocial variables than the other
two groups (p < .05).
Conclusions: In conclusion, patients with post-COVID-19 syndrome have experienced high pain intensity
and interference, central sensitization, increased insomnia severity, fear of movement, catastrophizing,
fear-avoidance beliefs, depression, anxiety, and stres
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