38 research outputs found

    On the "three-space problem" for spaces of polynomials.

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    A property P of locally convex spaces is called a three-space property whenever the following implication holds: if both a closed subspace F and the corresponding quotient E/F of a locally convex space E have P then E has P as well. The authors consider properties P of the form: E has P whenever two "natural'' topologies coincide on the spaces of n-homogeneous polynomials on E. They consider topologies of the uniform convergence on all absolutely convex compact or bounded subsets as well as the strong topology and the Nachbin ported topology. The results obtained are mostly negative and the counterexamples are variations of the known spaces

    (BB) properties on Fréchet spaces

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    In this paper we point out some relations concerning properties (BB)(n) and (BB)(n,s) related to the "Probleme des topologies" of Grothendieck and give a first example of a Frechet space with the (BB)(2) property but without the (BB)(3) property

    Propiedades (BB)n y topologías en P(nE)

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    Properties (BB)n, n = 2, 3, ... on a locally convex space (see the definition below) have been recently introduced ([10]). They are interesting, among other things, in connection with the study of natural topologies on spaces of polynomials, multilinear and holomorphic mappings. As it is proved in [1] there are Fr´echet spaces with the (BB)2 property but without the (BB)3 property. Here, for a given n = 3, ... we get an space without the property (BB)n+1 and study an equivalent condition for that space to have the (BB)n propert

    La magie mathématique comme outil de motivation Mathematical magic as a motivational tool

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    Attracting students into STEM disciplines is a necessary task. Of course demonstrations in physics or chemistry produce interaction and with people and engage them with science. Mathematics, despite its résumé ? summary 84 inner beauty, is far away from the main public but mathematical magic performances as the main skeleton of recreational mathematics activities has been proved useful. In this talk we discuss and introduce mathematical ideas by means of magic tricks, all of them with a mathematical background. In that sense we will deal with binary numbers, bipartition method, divisibility, logical decisions, probability, geometrical dissections and topology. So, abstract concepts are brought to general public in a more attractive way. There are deep mathematics in card shuffling and cards have been used to model different concepts. Using red/black properties it is easy dealing with even/odd numbers. Moreover, the position where a card arrives when a 'perfect' shuffle is made is related to binary numbers. Cards are also good for introducing coding systems. Finally, the movement on the stage and magician's presentation techniques are also good for communicating science and getting people attracted to these fields of knowledge

    γ-Linolenic acid in maternal milk drives cardiac metabolic maturation.

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    Birth presents a metabolic challenge to cardiomyocytes as they reshape fuel preference from glucose to fatty acids for postnatal energy production1,2. This adaptation is triggered in part by post-partum environmental changes3, but the molecules orchestrating cardiomyocyte maturation remain unknown. Here we show that this transition is coordinated by maternally supplied γ-linolenic acid (GLA), an 18:3 omega-6 fatty acid enriched in the maternal milk. GLA binds and activates retinoid X receptors4 (RXRs), ligand-regulated transcription factors that are expressed in cardiomyocytes from embryonic stages. Multifaceted genome-wide analysis revealed that the lack of RXR in embryonic cardiomyocytes caused an aberrant chromatin landscape that prevented the induction of an RXR-dependent gene expression signature controlling mitochondrial fatty acid homeostasis. The ensuing defective metabolic transition featured blunted mitochondrial lipid-derived energy production and enhanced glucose consumption, leading to perinatal cardiac dysfunction and death. Finally, GLA supplementation induced RXR-dependent expression of the mitochondrial fatty acid homeostasis signature in cardiomyocytes, both in vitro and in vivo. Thus, our study identifies the GLA-RXR axis as a key transcriptional regulatory mechanism underlying the maternal control of perinatal cardiac metabolism.S

    The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

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    Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

    Naturaleza y cultura en Ámerica Latina

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    La concreción del XVIII Foro de Estudiantes Latinoamericanos de Antrología y Arqueología: Cultura y naturaleza en América Latina: escenarios para un modelo de desarrollo no civilizatorio, efectuado en Quito desde el 17 al 23 de julio del 2011, se constituyó en un acontecimiento sumamente significativo para la antropología latinoamericana debido a dos motivos. Primero porque coincidió con la emergencia del movimiento universitario estudiantil latinoamericano que expresaba sus tendencias, propuestas y exigencias de cambios tanto de las prácticas académicas como de los patrones civilizatorios que rigen las relaciones actuales. Segundo, porque se inscribía en un contexto de consolidación de las nuevas democracias de los países andinos, de carácter antineoliberal y basadas en los sujetos de derecho entre los cuales se incluye la naturaleza. Estos contextos determinaron que el Foro no ponga en escena certidumbres teóricas o metodológicas, ni se preste al exhibicionismo estéril de los avances disciplinares. Más bien, la convocatoria de la antropología y la arqueología fue apenas un pretexto para hablar, con su lenguaje, de nosotros mismos, de lo que somos, de lo que pensamos, de lo que aspiramos y sentimos sobre nuestra Latinoamérica. Lo que hemos visto, oído y compartido, en realidad, no han sido solamente ideas o conceptos sino opciones y toma de posiciones respecto a múltiples encrucijadas. Posición ante situaciones que amenazan la vida, la justicia y los derechos de todos, un desafío epistemológico todavía en ciernes y que no termina de cuajar aún en nuestras prácticas académicas

    Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

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    Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Complementación, casinormabilidad y tonelación en espacios de polinomios

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    En el primer capitulo de la memoria se introducen las notaciones que se van a utilizar en el capitulo segundo se muestran casos en los que existe complementación en productos tensoriales de espacios localmente convexos, principalmente en productos tensoriales simetricos, para continuar probando que es un subespacio complementado de e. Se transportan estos resultados a resultados sobre complementación en espacios de polinomios homogéneos y se obtiene a partir de ellos que la propiedad implica la propiedad. En los capítulos tercero, cuarto y quinto se utilizan los resultados obtenidos en el segundo capitulo para proporcionar diversos ejemplos originales. Concretamente, en el tercer capitulo se construye un espacio e, que proporciona un primer ejemplo de espacio de frechet tal que es un espacio casi normable con todas las topologías habituales en espacios de polinomios, siendo todas ellas distintas entre si. En el cuarto capitulo se obtienen condiciones suficientes para la reflexividad de los productos tensoriales de espacios escalonados, en función de p y n, independientemente de a. Consecuentemente, se obtendrán condiciones suficientes para la reflexividad de . Se prueba también que cuando no verifica la condición de densidad de Heinrich, es tonelada sí y solo sí. En el quinto capítulo se estudian los espacios de sucesiones. Este estudio nos ayuda a construir nuevos contraejemplos a cuestiones clásicas: se construye un ejemplo de un espacio e que no verifica la condición de densidad heinrich pero para el que es reflexivo para cada . Este es el primer espacio conocido verificando esas condicione
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