Graph operations and Lie algebras

This paper deals with several operations on graphs and combinatorial structures linking them with their associated Lie algebras. More concretely, our main goal is to obtain some criteria to determine when there exists a Lie algebra associated with a combinatorial structure arising from those operations. Additionally, we show an algorithmic method for one of those operations.Ministerio de Ciencia e InnovaciónFondo Europeo de Desarrollo Regiona

Combinatorial structures of three vertices and Lie algebras

In this paper, we characterize digraphs of 3 vertices associated with Lie algebras according to isomorphism classes of these associated Lie algebras. At this respect, we introduce and implement two algorithmic methods: the first is devoted to draw the digraph associated with a given Lie algebra and the second allows us to determine if a given digraph is associated or not with a Lie algebra.Ministerio de Ciencia e InnovaciónFondo Europeo de Desarrollo Regiona

Design rules for antenna placement on MIMO systems

In recent works, it is demonstrated that, depending on the different spatial distributions and distance between elements, there exists a different true polarization diversity (TPD) configuration that provides a high improvement in terms of capacity. This means that it is necessary to choose the appropriate TPD configuration to maximize the multiple-input-multiple-output (MIMO) capacity. In this work, a genetic algorithm is used to optimize the element positions for four new different configurations in combination with the TPD technique. It is shown that, for some configurations, the same polarization option is always found to reach the maximum capacity. Based on this, some novel design rules are provided to maximize MIMO capacity when the area for placing the antennas is very small. This is the case for most of the wireless devices, where the antenna design and location is one of the latest design constraints to be taken into consideration in the device design

Broadband electronically tunable reflectionbased phase shifter for active-steering microwave reflectarray systems in Ku-band

This document provides the design of an electronically reconfigurable microwave phase shifter for reflectarray systems. The phase shifter is based on a hybrid coupler with reflective circuits in three ports. Each reflective circuit introduces a phase variation that can be modified due to the variable capacity value of a varactor inserted in it. The phase shifting process includes three different stages of phase shifting for the incoming signal in its way through the phase shifter: the signal is conducted through the device towards the reflective circuits in four different ways. The input port of the device is also the output one, providing the desired reflective phase shifting effect. This device is of great interest in reflectarray applications in order to provide more than 360° of controllable phase shifting at each array element. The document includes the complete design of the phase shifter along with its design parameters and circuital behaviour

Electronically reconfigurable reflective phase shifter for circularly polarized reflectarray systems

This letter presents the design of a two-port electronically reconfigurable phase shifter for circularly polarized reflectarray systems at microwave frequencies. The phase shifter is based on 3 dB/90? couplers combined with reflective circuits that introduce sequentially the phase variation. Each reflective circuit, formed by printed elements (L) and tunable varactors, produces the phase variation due to the variable capacity value of the varactor. The phase shifting process includes three different stages of phase shifting for the signal in its way from the input port towards the output port through the phase shifter. Both ports are interchangeable, acting either as input or output ports. This fulfils the reflection requirements of circularly polarized reflectarrays, being especially suitable for this purpose. The complete design, together with its circuital behavior and performance results, are depicted in this document

Electronically reconfigurable phase shifter for reflectarray applications at microwave bands

This contribution provides the design of a microwave phase shifter for active steerable reflectarray devices at microwave frequencies. The device is based on a 3dB hybrid coupler with three of its ports connected to reflective circuits. This reflective circuit is responsible of the phase variation by means of the use of an electrically controllable microwave varactor. More than 360° phase shifting is obtained with this device as the signal is conducted through the device towards the reflective circuits in three different stages. The input port of the device is also the output one, providing the desired phase shifting and the reflective effect. This device is of great interest in reflectarray applications in order to provide controllable phase shifting at each array element. The document includes the design of the different parts of the shifter along with the device design. Results, considerations and discussion are also provided in this work

Exposure to paracetamol and asthma symptoms

Multicenter study[Abstract] Background: Paracetamol is one of the factors that have been associated with the observed increase in asthma prevalence in the last few years. The influence of environmental or genetic factors in this disease may be different in some countries than in others. The purpose of this study was to analyse the relationship between the paracetamol consumption and asthma prevalence in our community. Methods: A cross-sectional study was conducted on more than 20,000 children and adolescents in Galicia, Spain. The International Study of Asthma and Allergies in Childhood methodology was used to collect the information on asthma symptoms in children, paracetamol consumption, body mass index (BMI), pets in the home, education level of the mother and parental asthma and smoking habits. The influence of paracetamol consumption on the prevalence of asthma symptoms was calculated using logistic regression, adjusted for the other parameters included in the study. Results: After adjusting for gender, BMI, having a cat or dog, maternal education, parental asthma and smoking, in 6- to 7-year-old children, the consumption of paracetamol during the first year of life is associated with asthma [odds ratio (OR) 2.04 (1.79-2.31) for wheezing at some time]. Paracetamol consumption in the previous year leads to a significant increase in the probability of wheezing at some time [OR 3.32 (2.51-4.41)] in young children and adolescents [OR 2.12 (1.68-2.67)]. Conclusions: Paracetamol consumption is associated with a significant increase in asthma symptoms. The effect is greater the more often the drug is taken

Impact of parental smoking on childhood asthma

[Abstract] Objective: To evaluate the exposure to environmental tobacco smoke (ETS) of the childhood population in this community and its relationship with asthma symptoms. Methods: A cross-sectional study was conducted using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire on children and adolescents in this community. The symptoms "wheezing ever", "current asthma", "severe asthma", and "exercise-induced asthma" were defined by this questionnaire. Parental smoking was classified into four mutually exclusive categories: 1) no parent smokes; 2) only the mother smokes; 3) only the father smokes; and 4) both parents smoke. The odds ratio of the prevalence of asthma symptoms according to ETS exposure was calculated using logistic regression. Results: A total of 10,314 children and 10,453 adolescents were included. Over 51% of the children and adolescents were exposed to ETS at home. ETS is associated with a higher prevalence of asthma symptoms, particularly if the mother or both parents smoke. Conclusion: The prevalence of ETS is still high in this community, although there has been a decreasing tendency in the last 15 years. ETS is associated with higher prevalence of asthma

Cross‐sectional study about impact of parental smoking on rhinitis symptoms in children

[Abstract] Objective. Assess the prevalence of rhinitis and exposure to environmental tobacco smoke (ETS) of children in our community and its relationship with symptoms of rhinitis Methods (design, setting, participants, main outcome measures). Cross‐sectional study using questionnaire on rhinitis of the International Study of Asthma and Allergies in Childhood, in children (6‐7 years) and adolescents (13‐14 years). Categories: “rhinitis ever”, “recent rhinitis”, “recent rhinoconjunctivitis”, “severe rhinoconjunctivitis”. Parental smoking: (i) neither parent smokes; (ii) only the mother smokes; (iii) only the father smokes; and (iv) both parents smoke. Odds ratio of the prevalence of symptoms of rhinitis according to ETS exposure was calculated using logistic regression. Results. 10 690 children and 10 730 adolescents. The prevalence of “rhinitis ever” in children: 29.4%, “recent rhinitis” 24%, “recent rhinoconjunctivitis” 11.5% and “severe rhinoconjunctivitis” 0.1%. In adolescents: 46.2%, 34.5%, 16.2% and 0.2%, respectively. Environmental tobacco smoke exposure in the home occurred in 51% of cases. Parental smoking was associated with a higher prevalence of forms of rhinitis in adolescents when only the mother was a smoker. In children when both parents were smokers. Conclusion. Rhinitis is highly prevalent in our community. Environmental tobacco smoke exposure is still very common. The relationship between ETS and rhinitis symptoms in children of this community is not as robust as that found for asthma

Trend di ospedalizzazione nell’asma dell’adulto: effetto di età e genere

Background: Hospital admissions due to asthma are a reliable source of information on the morbidity of the disease which, after the increase observed in the last quarter of the last century, shows a declining trend in the last few years. The aim of this study was to look at hospital admission trends due to asthma in our community and analyze some of its associated factors. Methods: Retrospective analysis of all hospital admissions involving adults aged 15 years and older with asthma as the primary or secondary diagnosis (if the first diagnosis was respiratory failure or respiratory infection) in Public Health Service hospitals in the Galician region of Spain between the years 1995-2009 (total 24,766 admissions). Results: The majority of patients admitted were female (71%), over 60 years of age (64%), and admission occurred predominantly in the winter months. The hospitalization rate due to asthma tripled over the period studied, this being mainly accounted for by women aged over 60 years. Mean hospital stay was 9.2 days, longer in older patients or those admitted over the weekend. Conclusions: A significant increase in hospital admissions due to asthma over the last few years has been observed in our community, mainly involving older women. The mean stay seems long, increasing with patients' age and admission over the weekend.Razionale: I ricoveri ospedalieri dovuti ad asma sono una fonte d’informazione attendibile sulla morbilità della patologia che, dopo un incremento osservato nell’ultimo quarto del secolo scorso, è in fase di declino negli ultimi anni. Scopo di questo studio era descrivere i trend di ospedalizzazione per asma nella nostra comunità ed analizzare alcuni dei fattori associati. Metodi: Analisi retrospettiva di tutte le ospedalizzazioni di adulti dai 15 anni in su per asma come diagnosi primaria, o come diagnosi secondaria in caso la prima diagnosi fosse insufficienza respiratoria o un’infezione respiratoria, in ospedali pubblici della regione Galizia della Spagna tra gli anni 1995 e 2009 (totale dei ricoveri: 24.766). Risultati: La maggioranza dei pazienti ricoverati erano femmine (71%), di età superiore a 60 anni (64%) e la maggior parte degli accessi avveniva nella stagione invernale. Il tasso di ospedalizzazione per asma è triplicato nel periodo studiato, soprattutto per le donne di età superiore a 60 anni. La durata media del ricovero era di 9,2 giorni, più prolungata nei pazienti più anziani ed in coloro che erano ricoverati nel fine settimana. Conclusioni: Un significativo incremento delle ospedalizzazioni per asma negli ultimi anni è stato osservato nella nostra comunità, soprattutto a carico delle donne più anziane. La durata media del ricovero appare lunga ed aumenta con l’età del paziente e nei ricoveri del fine settimana.S