288 research outputs found

    Analysis and Economic Evaluation of the Use of Recycled Polyamide Powder in Masonry Mortars

    Get PDF
    Due to the considerable amount of waste plastics and polymers that are produced annually, the introduction of these waste products in construction materials is becoming a recurrent solution to recycle them. Among polymers, polyamide represents an important proportion of polymer waste. In this study, sustainable and lightweight mortars were designed and elaborated, substituting the aggregates by polyamide powder waste. Mortars were produced with various dosages of cement/aggregates, and the polyamide substitutions were 25, 50, 75, and 100% of the aggregates. The aim of this paper is to determine the density and the compressive strength of the manufactured mortars to observe the feasibility for being employed as masonry or rendering and plastering mortars. Results showed that with increasing polymer substitution, lower densities were achieved, ranging from 1850 to 790 kg/m3 in modified mortars. Mortars with densities below 1300 kg/m3 are cataloged as lightweight mortars. Furthermore, compressive strength also decreased with more polyamide substitution. Obtained values in recycled mortars were between 15.77 and 2.10 MPa, but the majority of the values (eight out of 12) were over 5 MPa. Additionally, an economic evaluation was performed, and it was observed that the use of waste polyamide implies an important cost reduction, apart from the advantage of not having to manage this waste material. Consequently, not only the mechanical properties of the new recycled materials were verified as well as its economic viability

    Decreased pain in split-thickness skin graft donor sites with the use of a non-adherent polyurethane dressing

    Get PDF
    Donor sites of split-thickness skin grafts (STSGs) are painful and limit patient rehabilitation. We conducted this study to assess the efficacy of a non-adherent polyurethane dressing in reducing pain and its effect on the epithelialization rate of donor sites of STSGs. Methods: Fifteen patients requiring an STSG were included. In 10 patients the donor sites were randomly divided into two halves and covered with either a non-adherent polyurethane dressing or a standard non-adherent gauze. In five patients with bilateral donor sites, one side was covered with the non-adherent polyurethane dressing and the other with non-adherent gauze. The pain was assessed with a visual analog scale and epithelialization was also assessed, calculating non-epithelialized areas with image software by a blinded surgeon. Epithelialization of the wounds covered with the non-adherent polyurethane dressing was assessed at day 8 and 10 and those with non-adherent gauze at day 10. Results: Postoperative pain significantly decreased with the non-adherent polyurethane dressing during the length of the study (6.07 ± 1.46 vs. 1.72 ± 1.6) and at each time point (p < 0.001). Epithelialization was not affected with the polyurethane dressing, compared to the standard method

    Selection of AGN candidates in the GOODS-South Field through SPITZER/MIPS 24 μm variability

    Get PDF
    We present a study of galaxies showing mid-infrared variability in data taken in the deepest Spitzer/MIPS 24 μm surveys in the Great Observatory Origins Deep Survey South field. We divide the data set in epochs and subepochs to study the long-term (months–years) and the short-term (days) variability. We use a χ2-statistics method to select active galactic nucleus (AGN) candidates with a probability ≤1 per cent that the observed variability is due to statistical errors alone. We find 39 (1.7 per cent of the parent sample) sources that show long-term variability and 55 (2.2 per cent of the parent sample) showing short-term variability. That is, 0.03 sources × arcmin−2 for both, long-term and short-term variable sources. After removing the expected number of false positives inherent to the method, the estimated percentages are 1.0 and 1.4 per cent of the parent sample for the long term and short term, respectively. We compare our candidates with AGN selected in the X-ray and radio bands, and AGN candidates selected by their IR emission. Approximately, 50 per cent of the MIPS (Multiband Imaging Photometer for Spitzer) 24 μm variable sources would be identified as AGN with these other methods. Therefore, MIPS 24 μm variability is a new method to identify AGN candidates, possibly dust obscured and low-luminosity AGN, that might be missed by other methods. However, the contribution of the MIPS 24 μm variable identified AGN to the general AGN population is small (≤13 per cent) in GOODS-South.JG-G, AA-H, and AH-C acknowledge support from the Augusto G. Linares research programme of the Universidad de Cantabria and from the Spanish Plan Nacional through grant AYA2012-31447. PGP-G acknowledges support from MINECO grant AYA2012-31277.Peer Reviewe

    SHARDS: Constraints on the dust attenuation law of star-forming galaxies at z~2

    Get PDF
    We make use of SHARDS, an ultra-deep (<26.5AB) galaxy survey that provides optical photo-spectra at resolution R~50, via medium band filters (FWHM~150A). This dataset is combined with ancillary optical and NIR fluxes to constrain the dust attenuation law in the rest-frame NUV region of star-forming galaxies within the redshift window 1.5<z<3. We focus on the NUV bump strength (B) and the total-to-selective extinction ratio (Rv), targeting a sample of 1,753 galaxies. By comparing the data with a set of population synthesis models coupled to a parametric dust attenuation law, we constrain Rv and B, as well as the colour excess, E(B-V). We find a correlation between Rv and B, that can be interpreted either as a result of the grain size distribution, or a variation of the dust geometry among galaxies. According to the former, small dust grains are associated with a stronger NUV bump. The latter would lead to a range of clumpiness in the distribution of dust within the interstellar medium of star-forming galaxies. The observed wide range of NUV bump strengths can lead to a systematic in the interpretation of the UV slope (β\beta) typically used to characterize the dust content. In this study we quantify these variations, concluding that the effects are Δβ\Delta\beta~0.4.Comment: 13 pages, 11+2 figures, 3 tables. MNRAS, in pres

    Morphological studies of the Spitzer Wide-Area Infrared Extragalactic survey galaxy population in the UGC 10214 Hubble space telescope/advanced camera for surveys field

    Get PDF
    We present the results of a morphological analysis of a small subset of the Spitzer Wide-Area Infrared Extragalactic survey (SWIRE) galaxy population. The analysis is based on public Advanced Camera for Surveys (ACS) data taken inside the SWIRE N1 field, which are the deepest optical high-resolution imaging available within the SWIRE fields as of today. Our reference sample includes 156 galaxies detected by both ACS and SWIRE. Among the various galaxy morphologies, we disentangle two main classes, spheroids (or bulge-dominated galaxies) and disc-dominated ones, for which we compute the number counts as a function of flux. We then limit our sample to objects with Infrared Array Camera (IRAC) fluxes brighter than 10 μJy, estimated ~90 per cent completeness limit of the SWIRE catalogues, and compare the observed counts to model predictions. We find that the observed counts of the spheroidal population agree with the expectations of a hierarchical model while a monolithic scenario predicts steeper counts. Both scenarios, however, underpredict the number of late-type galaxies. These observations show that the large majority (close to 80 per cent) of the 3.6- and 4.5-μm galaxy population, even at these moderately faint fluxes, is dominated by spiral and irregular galaxies or mergers

    Finding influential nodes for integration in brain networks using optimal percolation theory

    Full text link
    Global integration of information in the brain results from complex interactions of segregated brain networks. Identifying the most influential neuronal populations that efficiently bind these networks is a fundamental problem of systems neuroscience. Here we apply optimal percolation theory and pharmacogenetic interventions in-vivo to predict and subsequently target nodes that are essential for global integration of a memory network in rodents. The theory predicts that integration in the memory network is mediated by a set of low-degree nodes located in the nucleus accumbens. This result is confirmed with pharmacogenetic inactivation of the nucleus accumbens, which eliminates the formation of the memory network, while inactivations of other brain areas leave the network intact. Thus, optimal percolation theory predicts essential nodes in brain networks. This could be used to identify targets of interventions to modulate brain function.Comment: 20 pages, 6 figures, Supplementary Inf

    Predicting synchronized gene coexpression patterns from fibration symmetries in gene regulatory networks in bacteria

    Full text link
    Background: Gene regulatory networks coordinate the expression of genes across physiological states and ensure a synchronized expression of genes in cellular subsystems, critical for the coherent functioning of cells. Here we address the question whether it is possible to predict gene synchronization from network structure alone. We have recently shown that synchronized gene expression can be predicted from symmetries in the gene regulatory networks described by the concept of symmetry fibrations. We showed that symmetry fibrations partition the genes into groups called fibers based on the symmetries of their ’input trees’, the set of paths in the network through which signals can reach a gene. In idealized dynamic gene expression models, all genes in a fiber are perfectly synchronized, while less idealized models—with gene input functions differencing between genes—predict symmetry breaking and desynchronization. Results: To study the functional role of gene fibers and to test whether some of the fiber-induced coexpression remains in reality, we analyze gene fibrations for the gene regulatory networks of E. coli and B. subtilis and confront them with expression data. We find approximate gene coexpression patterns consistent with symmetry fibrations with idealized gene expression dynamics. This shows that network structure alone provides useful information about gene synchronization, and suggest that gene input functions within fibers may be further streamlined by evolutionary pressures to realize a coexpression of genes. Conclusions: Thus, gene fibrations provide a sound conceptual tool to describe tunable coexpression induced by network topology and shaped by mechanistic details of gene expression

    Pathways to quiescence: SHARDS view on the star formation histories of massive quiescent galaxies at 1.0 < z < 1.5

    Get PDF
    et al.We present star formation histories (SFHs) for a sample of 104 massive (stellar massM> 1010 M) quiescent galaxies (MQGs) at z = 1.0-1.5 from the analysis of spectrophotometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) and HST/WFC3 G102 and G141 surveys of the GOODS-North field, jointly with broad-band observations from ultraviolet (UV) to far-infrared (far-IR). The sample is constructed on the basis of restframe UVJ colours and specific star formation rates (sSFRs = SFR/Mass). The spectral energy distributions (SEDs) of each galaxy are compared to models assuming a delayed exponentially declining SFH. A Monte Carlo algorithm characterizes the degeneracies, which we are able to break taking advantage of the SHARDS data resolution, by measuring indices such as MgUV and D4000. The population of MQGs shows a duality in their properties. The sample is dominated (85 per cent) by galaxies with young mass-weighted ages, t 1.0, when our galaxies were 0.5-1.0 Gyr old. According to these SFHs, all the MQGs experienced a luminous infrared galaxy phase that lasts for ~500 Myr, and half of them an ultraluminous infrared galaxy phase for ~100 Myr. We find that the MQG population is almost assembled at z ~ 1, and continues evolving passively with few additions to the population.We acknowledge support from the Spanish Programa Nacional de Astronomía y Astrofísica under grants AYA2012-31277. NCL acknowledges financial support from AYA2013-46724-P. AAH and AHC acknowledge support from the Spanish Programa Nacional de Astronomía y Astrofísica under grant AYA2012-31447, which is partly funded by the Fondo Europeo de Desarrollo Regional programme. The work of AC is supported by the STARFORM Sinergia Project funded by the Swiss National Science Foundation. SC acknowledges support from the ERC via an Advanced Grant under grant agreement no. 321323-NEOGAL. DC thanks AYA2012-32295. GB acknowledges support for this work from the National Autonomous University of México (UNAM), through grant PAPIIT IG100115.Peer Reviewe

    ¿Qué hacemos con el quiste pilonidal?

    Get PDF
    La enfermedad pilonidal, es una infección aguda o crónica que suele afectar la región sacrococcígea. Se trata de una afección frecuente y que aparece descripta por primera vez por Mayo en 1833. Su curso es benigno (0.1% se malignizan a carcinoma escamoso) y sorprende cuando se comparan estos datos con la magnitud de la morbilidad y el riesgo de recidivas. Existen diversas modalidades de tratamiento para la enfermedad pilonidal, y se describen operaciones no resectivas, como el desteche, operación de Buie o marsupializacion, hasta la resección total de la misma y la reparación del defecto con un colgajo. Toda esa gama de cirugías se han ido utilizando y modificando en post de objetivos comunes como son acortar el tiempo de cicatrización con una vuelta a las actividades más rápida y lograr un menor indice de recidivas. El objetivo de la presente publicación es mostrar la utilización del cierre mediante colgajo de Dufourmentel como alternativa valida para el tratamiento de la enfermedad pilonidal sea esta complicada o no. Para ello se presentan 7 casos operados entre el 1/8/2019 y 1/6/2022 donde se utilizo la técnica de resección y cierre primario mediante colgajo.Facultad de Ciencias Médica
    corecore