1,075 research outputs found
Caracterización de morteros con cerámica reciclada y su uso en piezas prefabicadas para entrevigado de forjados
This study analyses a procedure to manufacture mortars with different percentages of ceramic waste as partial replacement for aggregates. The study also examines the physical, chemical and mechanical properties of the new mortars, analysing substitution ratios that range from 10% to 50%. Prior to this, all the materials used in the production of the mortar were characterised using X-ray diffraction (XRD) and fluorescence (XRF). The objective was to determine the similarity between different types of ceramic waste, as well as the differences in the minerology and chemical composition with the aggregate.
The results of the study show that it is possible to obtain mortars with lower densities compared to the same product with no recycled content. The product’s characteristics make it ideal for the manufacture of prefabricated components for structural floors for rehabilitation works. Finally, the pieces are used in a real rehabilitation case study, highlightining the structural advantages.Este trabajo analiza morteros con diferentes porcentajes de cerámica reciclada como sustituto parcial de la arena. Además el estudio examina las propiedades físicas, químicas y mecánicas de los nuevos morteros, empleando diferentes porcentajes de sustitución (10% - 50%). Con anterioridad, se caracterizaron todos los materiales empleados en este trabajo mediante difracción y fluorescencia de rayos-X. El objetivo fue determinar las diferencias y similitudes en la composición química y mineralógica de los distintos tipos de residuos cerámicos y del resto de áridos utilizados.
Los resultados muestran que es posible obtener morteros con menor densidad frente a las muestras sin contenido reciclado. Sus características los hacen idóneos para la creación de piezas prefabricadas de entrevigado para rehabilitación de forjados. Finalmente. Las piezas se usaron en un caso de estudio real, destacando las ventajas estructurales que conlleva su uso
Parques temáticos en Colombia : construyendo empresas perdurables que acepten el desafío de subirse a la montaña de la turbulencia global
En la actualidad, las personas buscan actividades culturales y de entretenimiento
que les permitan compartir y disfrutar momentos de esparcimiento
con sus familiares y amigos. Una de esas alternativas se encuentra en los
parques temáticos, los cuales emergen como espacios en donde no solo se
puede disfrutar de atracciones mecánicas y participar en dinámicas, sino
también aprender, por medio de educación no formal, acerca de temáticas
culturales, sociales e históricas que hacen parte de nuestra comunidad y que
demandan ser transmitidas a personas de cualquier edad.
Más allá de la importancia cultural y educacional que caracteriza a los
parques temáticos, estos lugares de entretenimiento contribuyen en gran
proporción a la atracción de visitantes y, por ende, al incremento del turismo
en un determinado territorio. En el caso colombiano, el sector turístico ha
cobrado importancia en los últimos años, convirtiéndose en uno de los más
importantes generadores de divisas después de la exploración y comercialización
del petróleo y el carbón
A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU
Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).Our nearest neighbor, Proxima Centauri, hosts a temperate terrestrial planet. We detected in radial velocities evidence of a possible second planet with minimum mass m c sin i c = 5.8 ± 1.9 M ⊕ and orbital period P c = 5.21 - 0.22 + 0.26 years. The analysis of photometric data and spectro-scopic activity diagnostics does not explain the signal in terms of a stellar activity cycle, but follow-up is required in the coming years for confirming its planetary origin. We show that the existence of the planet can be ascertained, and its true mass can be determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c could become a prime target for follow-up and characterization with next-generation direct imaging instrumentation due to the large maximum angular separation of ~1 arc second from the parent star. The candidate planet represents a challenge for the models of super-Earth formation and evolution.Peer reviewedFinal Published versio
Stellar Diameters and Temperatures II. Main Sequence K & M Stars
We present interferometric diameter measurements of 21 K- and M- dwarfs made
with the CHARA Array. This sample is enhanced by literature radii measurements
to form a data set of 33 K-M dwarfs with diameters measured to better than 5%.
For all 33 stars, we compute absolute luminosities, linear radii, and effective
temperatures (Teff). We develop empirical relations for \simK0 to M4 main-
sequence stars between the stellar Teff, radius, and luminosity to broad-band
color indices and metallicity. These relations are valid for metallicities
between [Fe/H] = -0.5 and +0.1 dex, and are accurate to ~2%, ~5%, and ~4% for
Teff, radius, and luminosity, respectively. Our results show that it is
necessary to use metallicity dependent transformations to convert colors into
stellar Teffs, radii, and luminosities. We find no sensitivity to metallicity
on relations between global stellar properties, e.g., Teff-radius and
Teff-luminosity. Robust examinations of single star Teffs and radii compared to
evolutionary model predictions on the luminosity-Teff and luminosity-radius
planes reveals that models overestimate the Teffs of stars with Teff < 5000 K
by ~3%, and underestimate the radii of stars with radii < 0.7 R\odot by ~5%.
These conclusions additionally suggest that the models overestimate the effects
that the stellar metallicity may have on the astrophysical properties of an
object. By comparing the interferometrically measured radii for single stars to
those of eclipsing binaries, we find that single and binary star radii are
consistent. However, the literature Teffs for binary stars are systematically
lower compared to Teffs of single stars by ~ 200 to 300 K. Lastly, we present a
empirically determined HR diagram for a total of 74 nearby, main-sequence, A-
to M-type stars, and define regions of habitability for the potential existence
of sub-stellar mass companions in each system. [abridged]Comment: 73 pages, 12 Tables, 18 Figures. Accepted for publication in The
Astrophysical Journa
Perinatal asphyxia: CNS development and deficits with delayed onset
Perinatal asphyxia constitutes a prototype of obstetric complications occurring when pulmonary
oxygenation is delayed or interrupted. The primary insult relates to the duration of the period
lacking oxygenation, leading to death if not re-established. Re-oxygenation leads to a secondary
insult, related to a cascade of biochemical events required for restoring proper function. Perinatal
asphyxia interferes with neonatal development, resulting in long-term deficits associated to mental
and neurological diseases with delayed clinical onset, by mechanisms not yet clarified.
In the experimental scenario, the effects observed long after perinatal asphyxia have been explained
by over expression of sentinel proteins, such as poly(ADP-ribose) polymerase-1 (PARP-1),
competing for NAD+ during re-oxygenation, leading to the idea that sentinel protein inhibition
constitutes a suitable therapeutic strategy. Asphyxia induces transcriptional activation of proinflammatory
factors, in tandem with PARP-1 overactivation, and pharmacologically induced
PARP-1 inhibition also down-regulates the expression of proinflammatory cytokines.
Nicotinamide has been proposed as a suitable PARP-1 inhibitor. Its effect has been studied in
an experimental model of global hypoxia in rats. In that model, the insult is induced by immersing
rat foetuses into a water bath for various periods of time. Following asphyxia, the pups are
delivered, treated, and nursed by surrogate dams, pending further experiments. Nicotinamide
rapidly distributes into the brain following systemic administration, reaching steady state
concentrations sufficient to inhibit PARP-1 activity for several hours, preventing several of the
long-term consequences of perinatal asphyxia, supporting the idea that it constitutes a lead for
exploring compounds with similar or better pharmacological profiles
Characterizing the Cool KOIs II. The M Dwarf KOI-254 and its Hot Jupiter
We report the confirmation and characterization of a transiting gas giant
planet orbiting the M dwarf KOI-254 every 2.455239 days, which was originally
discovered by the Kepler mission. We use radial velocity measurements, adaptive
optics imaging and near infrared spectroscopy to confirm the planetary nature
of the transit events. KOI-254b is the first hot Jupiter discovered around an
M-type dwarf star. We also present a new model-independent method of using
broadband photometry to estimate the mass and metallicity of an M dwarf without
relying on a direct distance measurement. Included in this methodology is a new
photometric metallicity calibration based on J-K colors. We use this technique
to measure the physical properties of KOI-254 and its planet. We measure a
planet mass of Mp = 0.505 Mjup, radius Rp = 0.96 Rjup and semimajor axis a =
0.03 AU, based on our measured stellar mass Mstar = 0.59 Msun and radius Rstar
= 0.55 Rsun. We also find that the host star is metal-rich, which is consistent
with the sample of M-type stars known to harbor giant planets.Comment: AJ accepted (in press
El libro blanco de la influencia responsable
Este libro tiene como objetivos promover la influencia responsable en las redes sociales,
definir el ecosistema de la influencia, identificar las palancas que impulsan la confianza en
torno al Influencer y mejorar la credibilidad, transparencia y eficacia del sector.
El Libro Blanco tiene su origen en el conocimiento adquirido por iCmedia a raíz del desarrollo
del Influencer Trust Label (ITL). El ITL es un proyecto cofinanciado por la Unión Europea, en
el que iCmedia ha trabajado durante los últimos 18 meses. A través de él, iCmedia ha creado
una Etiqueta de Confianza para los perfiles de las redes sociales de los Influencers. Esta
etiqueta establece unos indicadores de responsabilidad y transparencia, que distinguen a
aquellos influencers, marcas y agencias que actúan de modo responsable. Para realizar la
Etiqueta de Confianza ITL se trabajó con influencers de toda España a través de focus groups.
El Libro Blanco de la Influencia Responsable es el resultado de una gran conversación
entre los stakeholders que forman el ecosistema de la influencia: usuarios y consumidores,
influencers, marcas, agencias, medios de comunicación, plataformas sociales, instituciones
y organizaciones, y reguladores. Entre todos, se dibujan y proponen los pasos a seguir para
hacer real un entorno de influencia responsable.
Para llevar a cabo este proyecto, se ha realizado una exhaustiva recogida de información a
través de más 40 entrevistas en profundidad a los representantes más destacados de los
agentes que componen el ecosistema de la influencia digital. Durante estas entrevistas,
se ha analizado la situación actual, descrito los retos y palancas de cambio de la influencia
responsable, y se han determinado las recomendaciones y pasos a seguir para crear un
entorno de influencia responsable promovido por todas las partes implicadas.
Este libro presenta los resultados de todo este trabajo de investigación.
El Libro Blanco de la Influencia Responsable pretende impulsar en todos los usuarios,
influencers y stakeholders del ecosistema de la influencia digital, el conocimiento del poder de
influencia de los Influencers digitales y del impacto que tienen en la sociedad, especialmente
en los menores. Todos juntos debemos caminar hacia la Influencia Responsable
Photo-reverberation mapping of a protoplanetary accretion disk around a T Tauri star
This is the final version. Available from the American Astronomical Society via the DOI in this recordTheoretical models and spectroscopic observations of newborn stars suggest that protoplantary disks have an inner "wall" at a distance set by the disk interaction with the star. Around T Tauri stars, the size of this disk hole is expected to be on a 0.1 au scale that is unresolved by current adaptive optics imaging, though some model-dependent constraints have been obtained by near-infrared interferometry. Here we report the first measurement of the inner disk wall around a solar-mass young stellar object, YLW 16B in the ρ Ophiuchi star-forming region, by detecting the light-travel time of the variable radiation from the stellar surface to the disk. Consistent time lags were detected on two nights, when the time series in H (1.6 μm) and K (2.2 μm) bands were synchronized while the 4.5 μm emission lagged by 74.5 ± 3.2 s. Considering the nearly edge-on geometry of the disk, the inner rim should be 0.084 au from the protostar on average, with an error of order 0.01 au. This size is likely larger than the range of magnetospheric truncations and consistent with an optically and geometrically thick disk front at the dust sublimation radius at ∼1500 K. The widths of the cross-correlation functions between the data in different wavebands place possible new constraints on the geometry of the disk.National Science Foundation (NSF
Influence of profilin on sensitisation profiles determined by cutaneous tests and IgE to major allergens in polysensitised patients
Background: Profilin sensitisation is considered a diagnostic confounding factor in areas where patients are exposed to multiple pollens. The aim of this study is to assess pollen sensitisation profiles in adults and children and to evaluate, by means of component-resolved diagnosis (CRD) and skin prick testing (SPT), which pollens may be considered as risk factors of profilin sensitisation in order to establish the best diagnostic approach in polysensitised patients. Methods: A total of 231 pollen-allergic patients (adults and children) were included, out of the pollen season, from an area with similar levels of pollen exposure. Allergological diagnosis was performed by SPT and determination of specific IgE (sIgE) to major allergen components (ADVIA-Centaur™). Patients had not received immunotherapy in the last 5 years and had to reside in the area for 5 consecutive years before entering the study. Results: The relation between sensitisation measured by SPT and by sIgE was studied using a model of cases (patients with +sIgE to a specific allergen) and controls (patients with -sIgE to the same allergen). The outcome, in terms of odds-ratios (OR), was statistically significant for Olea (Ole e 1) (p = 0.0005), Salsola (Sal k 1) (p = 0.0118) and Platanus (Pla a 1+ 2) (p = 0.0372). While positivity of SPT to most pollens was statistically associated with a risk of profilin sensitisation, by CRD the association was statistically significant only for Ole e 1 (OR 3.5, CI 95 %, 1.6-7.6, p = 0.0014), and Phl p 5 (OR 11.9, CI 95 %, 4.1-35.2, p < 0.001). When analysing this association using a logistic regression model, Phl p 5 was the only allergen associated with the risk of being sensitised to profilin (p = 0.0023). Conclusions: In patients sensitised to profilin, the concordance between SPT and CRD is much lower than in those not sensitised to profilin. CRD is able to provide refined information about which pollens increase the risk of sensitisation to profilin
Factors of the epidemiological triad that influence the persistence of human papilloma virus infection in women with systemic lupus erythematosus
We studied the epidemiologic triad-related factors influencing human papilloma virus (HPV) persistence in Mexican women with systemic lupus erythematosus (SLE). Patients aged ?18 years with SLE (American College of Rheumatology criteria), with and without HPV persistence, were selected. Groups were analyzed by (1) host: clinical disease characteristics; (2) agent: (I) infectious (prevalence, incidence, HPV genotype and co-infections (?2 HPV genotypes or mycoplasmas)), (II) chemical (contraceptives and immunosuppressive drugs) and (III) physical (vitamin D deficiency) and (3) environment. A total of 121 SLE patients were selected over a two-year period. (1) Host: mean age 45.8 years and disease duration 12.7 years. (2) Agent: (I) infectious. HPV infection prevalence in the second sample was 26.4%, high-risk HPV genotypes 21.5% and co-infections 7.4%. HPV infection incidence was 13.2%, persistence 13.2% and clearance 15.7%. (II) Chemical: use of oral hormonal contraceptives 5% and immunosuppressive treatment 97.5%. (III) Physical: Vitamin D levels were similar in both groups. (3) Environment: (I) natural. A total of 60.6% of patients were residents of Puebla City. (II) Social: The mean education level was 10.9. Poverty levels were: III degree 52.4%, IV degree 28% and II degree 17%. (III) Cultural behavioral: Onset of sexual life was 20.5 years, 10% had ?3 sexual partners and 51.2% were postmenopausal. In conclusion, no factor of the epidemiologic triad was associated with HPV infection prevalence. © The Author(s) 2018
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