130 research outputs found

    Optimal Control and Sensitivity Analysis of a Fractional Order TB Model

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    A Caputo fractional-order mathematical model for the transmission dynamics of tuberculosis (TB) was recently proposed in [Math. Model. Nat. Phenom. 13 (2018), no. 1, Art. 9]. Here, a sensitivity analysis of that model is done, showing the importance of accuracy of parameter values. A fractional optimal control (FOC) problem is then formulated and solved, with the rate of treatment as the control variable. Finally, a cost-effectiveness analysis is performed to assess the cost and the effectiveness of the control measures during the intervention, showing in which conditions FOC is useful with respect to classical (integer-order) optimal control.Comment: This is a preprint of a paper whose final and definite form is with 'Statistics Opt. Inform. Comput.', Vol. 7, No 2 (2019). See [http://www.IAPress.org]. Submitted 09/Sept/2018; Revised 10/Dec/2018; Accepted 11/Dec/2018. arXiv admin note: text overlap with arXiv:1801.09634, arXiv:1810.0690

    Optimal control of a fractional order epidemic model with application to human respiratory syncytial virus infection

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    A human respiratory syncytial virus surveillance system was implemented in Florida in 1999, to support clinical decision-making for prophylaxis of premature newborns. Recently, a local periodic SEIRS mathematical model was proposed in [Stat. Optim. Inf. Comput. 6 (2018), no.1, 139--149] to describe real data collected by Florida's system. In contrast, here we propose a non-local fractional (non-integer) order model. A fractional optimal control problem is then formulated and solved, having treatment as the control. Finally, a cost-effectiveness analysis is carried out to evaluate the cost and the effectiveness of proposed control measures during the intervention period, showing the superiority of obtained results with respect to previous ones.Comment: This is a preprint of a paper whose final and definite form is with 'Chaos, Solitons & Fractals', available from [http://www.elsevier.com/locate/issn/09600779]. Submitted 23-July-2018; Revised 14-Oct-2018; Accepted 15-Oct-2018. arXiv admin note: substantial text overlap with arXiv:1801.0963

    The role of service life planning in construction industry; an exploratory review

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    ARTICULO ESPECIALIZADO PUBLICADO EN REVISTA INTERNACIONAL INDEXADAThe aim is to present a review of the scientific literature as regards service life planning and durability in buildings, infrastructure and their parts. The review focused on studies and works related to two main categories: the first related to the basic information on service life planning for buildings, the second, related to case studies and applications of service life planning in buildings. Results reveal that as regards theory and basic information on service life the studies mainly focus on studies on specific methods and models on service life planning in buildings and their components, as for applications and case studies, these largely focus on life cycle assessments to ascertain durability and environmental impacts for various materials and constructive components. It is concluded that the estimation of a building’s service life not only comes in handy to plan its durability, but also because it is very useful when studies on Life-cycle assessment on buildings and their components are needed

    Application of self-healing materials in architecture and construction industry: an exploratory review

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    ARTÍCULO ESPECIALIZADO EN REVISTA INTERNACIONAL INDEXADAThis work’s aim was to perform a review of the scientific literature from the standpoint of both the architect and builder. In the first place, on which self-healing materials are currently available for construction industry; secondly, to acknowledge the main applications and the self-healing methods of each material. The review was largely carried out using the scientific database tool sciencedirect® and other similar tools on the main applications of self-healing materials in construction industry. The results reveal that the main applications refer to the production of self-healing concretes and mortars by means of self-healing techniques, for example: insertion of microcapsules with various self-healing agents, followed by self-healing bacteria. It is concluded that with the use of these materials not only does the service life of structures of buildings improves, but also that of the entire building, increasing durability and noticeably decreasing maintenance and reparation costs

    On race and ethnicity during a global pandemic:An 'imperfect mosaic' of maternal and child health services in ethnically-diverse South London, United Kingdom

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    BACKGROUND: The SARS-CoV-2 pandemic has brought racial and ethnic inequity into sharp focus, as Black, Asian, and Minority Ethnic people were reported to have greater clinical vulnerability. During the pandemic, priority was given to ongoing, reconfigured maternity and children's healthcare. This study aimed to understand the intersection between race and ethnicity, and healthcare provision amongst maternity and children's healthcare professionals, during the SARS-CoV-2 pandemic. METHODS: A qualitative study consisting of semi-structured interviews (N = 53) was undertaken with maternity (n = 29; August-November 2020) and children's (n = 24; June-July 2021) healthcare professionals from an NHS Trust in ethnically-diverse South London, UK. Data pertinent to ethnicity and race were subject to Grounded Theory Analysis, whereby data was subjected to iterative coding and interpretive analysis. Using this methodology, data are compared between transcripts to generate lower and higher order codes, before super-categories are formed, which are finally worked into themes. The inter-relationship between these themes is interpreted as a final theory. FINDINGS: Grounded Theory Analysis led to the theory: An ‘Imperfect Mosaic’, comprising four themes: (1) ‘A System Set in Plaster’; (2) ‘The Marginalised Majority’; (3) ‘Self-Discharging Responsibility for Change-Making’; and (4) ‘Slow Progress, Not No Progress’. The NHS was observed to be brittle, lacking plasticity to deliver change at pace. Overt racism based on skin colour has been replaced by micro-aggressions between in-groups and out-groups, defined not just by ethnicity, but by other social determinants. Contemporaneously, responsibility for health, wellbeing, and psychological safety in the workplace is discharged to, and accepted by, the individual. INTERPRETATION: Our findings suggest three practicable solutions: (1) Representation of marginalised groups at all NHS levels; (2) Engagement in cultural humility which extends to other social factors; and (3) Collective action at system and individual levels, including prioritising equity over simplistic notions of equality. FUNDING: This service evaluation was supported by the King's College London King's Together Rapid COVID-19 Call, successfully awarded to Laura A. Magee, Sergio A. Silverio, Abigail Easter, & colleagues (reference:- 204823/Z/16/Z), as part of a rapid response call for research proposals. The King's Together Fund is a Wellcome Trust funded initiative

    Simulación determinística y estocástica para dimensionar, y seleccionar equipo y elegir alternativas de minado en la explotación minera superficial

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    Mine equipment selection is a complex task due to numerous technical, geometrical and economical variables involved. The variety of equipment manufacturers and agents carrying different models, types and sizes make the selection procedure even more complex. The mine planner does not have a tool to correctly select the equipment or fl eet for a project. Simulation fi lls the gap and contributes to this goal. This study tries to apply deterministic and probabilistic simulation approaches in selecting mining equipment using fi eld data from two surface mine operations. The deterministic model uses a one year production plan from a quarry. The equipment fl eet is selected on the basis of minimum unit cost for both drilling and excavation-haulage equipment fl eets. For the probabilistic approach the GPSS language is applied. Programs were prepared for various combinations of loaders and haulers and data from a metallic open pit mine was processed. The optimum fl eet was selected by combining minimum cost per ton mined and maximum production tonnage per time unit.La elección óptima de equipo en minería superfi cial es una tarea compleja donde intervienen muchas variables técnicas, geométricas y económicas en un ambiente donde existen muchas marcas, modelos y tamaños que compiten por el usuario. El técnico que efectúa la selección no tiene una herramienta apropiada que le permita evaluarlos y decidir por el mejor. La simulación contribuye a efectuar esta selección. En este estudio se desarrolla los modelos determinístico y probabilístico de simulación aplicados a equipos de minado con datos de dos operaciones superfi ciales. En el caso determinístico se simula la producción proyectada de un año de una cantera y en base a costo unitario mínimo se elige la fl ota de equipos tanto en perforación como en acarreo. En la simulación probabilística se usa el lenguaje GPSS para simular modelos de excavación y acarreo para varias combinaciones de cargadores y transportadores eligiendo el mas apropiado para las características de la operación en base a costo unitario mínimo y máxima producción unitaria

    Trauma craneoencefálico en motociclistas, Hospital Traumatológico Ney Arias Lora.

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    Introducción: El trauma craneoencefálico es un problema de salud global que limita al individuo en las esferas motora, cognitiva y del comportamiento, es el primer productor de discapacidad a nivel mundial y la primera causa de muerte en personas entre los 15 a 45 años de edad. Objetivo: Determinar la frecuencia del uso correcto de casco protector en pacientes con trauma craneoencefálico por accidente de tránsito en motocicleta en el Hospital Traumatológico Ney Arias Lora. Métodos: Se realizó un estudio observacional descriptivo, de corte transversal. El universo estuvo constituido por un total de 149 casos de trauma craneoencefálico en motociclistas. Se emplearon estadígrafos de estadística descriptiva, con uso del programa SPSS 2.0. Resultados: De 149 casos estudiados, en 128 se encontró que no utilizaron el casco protector, correspondiendo al 86%. Los pacientes con edades entre 19 y 45 años conformaron la mayoría de casos con un total de 93 pacientes para un 65%. Los pacientes del género masculino representaron la mayoría, 138 casos para un 93%. Sobre la clasificación del trauma, del grupo de pacientes que usaron correctamente el casco de seguridad no hubo casos severos y de los que no lo usaron, 20 casos fueron severos para un 15,5%. Conclusiones: El uso de casco de seguridad disminuye la gravedad del trauma craneoencefálico en motociclistas sufrieron accidente de tránsito. El trauma de forma general, se ubica entre las primeras causa de muerte en República Dominicana. Especialmente el trauma craneoencefálico afectó a personas jóvenes por lo que representó una gran cantidad de años potencialmente perdidos entre las víctimas; de manera que debe sensibilizarse a la población sobre la importancia del uso del caso de protección, toda vez que solo la quinta parte de los accidentados o usaron

    Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates

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    We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASSJ19104752+4220194. We find a stellar effective temperature Teff=5455+-100K, a metallicity of [Fe/H]=0.01+-0.04, and a surface gravity of log(g)=4.4+-0.1. Combined with an estimate of the stellar density from the transit light curves we deduce a stellar mass of Mstar=0.912+-0.034 Msun and a stellar radius of Rstar=0.944^{+0.060}_{-0.095} Rsun. For three of the transit signals, our results strongly disfavor the possibility that these result from astrophysical false positives. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2e5 (Kepler-20b), 1e5 (Kepler-20c), and 1.1e3 (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: From Spitzer data gathered at 4.5um, we infer a ratio of the planetary to stellar radii of 0.075+-0.015 (Kepler-20c) and 0.065+-0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70d and 1.91^{+0.12}_{-0.21} Rearth for Kepler-20b, 10.85 d and 3.07^{+0.20}_{-0.31} Rearth for Kepelr-20c, and 77.61 d and 2.75^{+0.17}_{-0.30} Rearth for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7\+-2.2 Mearth and 16.1+-3.5 Mearth, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 Mearth (2 sigma).Comment: accepted by ApJ, 58 pages, 12 figures revised Jan 2012 to correct table 2 and clarify planet parameter extractio

    Síntomas de pacientes antes de la primera hospitalización por Síndrome Coronario Agudo

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    Este estudo objetivou caracterizar os pacientes quanto ao relato da presença de sintomas de dor torácica, dispneia e limitação das atividades diárias uma semana antes da primeira hospitalização por Síndrome Coronariana Aguda, segundo a forma de apresentação clínica, e compará-las. Estudo transversal, descritivo e correlacional. Utilizou-se um instrumento de avaliação clínica que investigou a presença e a gravidade dos sintomas de dispneia, precordialgia e restrição física decorrentes da isquemia do miocárdio. Com relação à limitação para realização de atividades físicas, pacientes com diagnóstico de angina instável mostraram maior comprometimento na semana que antecedeu a internação, assim como relataram a presença de dispneia e precordialgia com maior frequência do que os pacientes infartados em situações que vão desde realizarem grandes esforços como, por exemplo, caminhar na subida ou muito rápido no plano, até situações de repouso ou de pequenos esforços.The objective of this study was to characterize and compare patients regarding their report of experiencing chest pain, dyspnea and limitation of the daily life activities one week before their first hospitalization due to Acute Coronary Syndrome, according to the clinical presentation form, and compare them. This is a cross-sectional, descriptive and correlational study. A clinical evaluation instrument was used to investigate the presence and severity of dyspnea, chest pain and physical restriction due to myocardial ischemia. Regarding the limitation to carry out physical activities, patients diagnosed with unstable angina showed lower capacity the week before hospitalization, and reported experiencing dyspnea and chest pain more frequently than patients who had an infarction in situations ranging from making strong efforts, such as walking uphill or on a flat surface but very quickly, to resting and in situations of little effort.Estudio que objetivó caracterizar a pacientes en cuanto al relato de presencia de síntomas de dolor torácico, disnea y limitación de actividades diarias una semana antes de la primera hospitalización por Síndrome Coronario Agudo, según la forma de presentación clínica, y compararlas. Estudio transversal, descriptivo y correlacional. Se utilizó un instrumento de evaluación clínica que investigó la presencia y gravedad de síntomas de disnea, precordialgia y restricción física derivadas de isquemia de miocardio. En relación a limitaciones para realización de actividades físicas, pacientes con diagnóstico de angina inestable mostraron mayor compromiso en la semana que antecedió a la internación, así como relataron la presencia de disnea y precordialgia con mayor frecuencia que en los pacientes infartados en situaciones tales como realizar grandes esfuerzos como, por ejemplo, caminar en pendiente ascendiente o muy rápido en el llano, hasta situaciones de reposo o pequeños esfuerzos
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