185 research outputs found

    Energy efficient operation of photocatalytic reactors based on UV LEDs for pollution remediation in water.

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    Photocatalytic technology using TiO2 is one of the emerging approaches for water treatment, especially as a final step to remove complex organics such as pesticides, hormones or humic acids. Titanium dioxide (TiO2) is a semiconductor material with strong UV absorption band and exhibits strong photocatalytic activity. The photocatalytic activity of TiO2 powders have been extensively studied, using UV light sources. However, the incident photons that initiate the process of photocatalytic oxidation using titanium dioxide are not efficiently used, this is responsible for the low photonic efficiency that characterise oxidation of aqueous pollutants hence its limitation in industrial applications. Periodic illumination has been investigated as a means of increasing the photonic efficiency in a photoreactor with acid orange as a model pollutant. Results indicate more than four-fold increase in photonic efficiency through periodic illumination compared to continuous illumination. This approach can improve the energy efficiency of the photocatalytic water treatment systems

    Decolonizar la investigación sobre migraciones : apuntes desde una etnografía colaborativa

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    En este artículo analizamos los significados asumidos por la idea de "(in)migración(es)" y la categoría de "(in)migrante(s)" en los contextos sociales, políticos y académicos contemporáneos. Resaltando su estrecha relación con el pensamiento de Estado y la colonialidad del poder/saber, nos preguntamos por otros posibles acercamientos a la movilidad humana. Discutimos la etnografía colaborativa, entendida como una metodología decolonial que rechaza las representaciones pasivizantes hegemónicas y aspira a visibilizar los procesos de subjetivación política de las personas junto a las que se investiga. Aportando ejemplos de nuestra propia investigación colaborativa junto a Stop Desahucios-Granada 15M, ilustramos cómo la idea de (in)migración(es) y la categoría "(in)migrante(s)" se han materializado en nuestro contexto, que se encuentra definido por el activismo político y no había sido previamente alterizado como "migratorio". Concluimos resaltando la ambivalencia implícita en estas dos expresiones y reflexionamos sobre los pros y los contras implícitos en su uso.In this paper we analyze the meaning of "immigration" and "immigrant" within contemporary social, political and academic contexts. We emphasize their narrow relation with State thought and the coloniality of power/knowledge and search for alternative approaches to human mobility. With this aim, we discuss collaborative ethnography as a decolonial methodology addressed to visibilize the political subjectivation processes of the people we research with. Drawing on examples from our own collaborative research with Stop Evictions-Granada 15M, we show how the idea of "immigration" and the category "immigrants" have come into being within our field, a space of political activism which had not been previously constructed as a "migratory context". We conclude underlining the ambivalence implicit in the two aforementioned concepts and discuss the pros and cons of using them

    The Dynamics of Brane-World Cosmological Models

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    Brane-world cosmology is motivated by recent developments in string/M-theory and offers a new perspective on the hierarchy problem. In the brane-world scenario, our Universe is a four-dimensional subspace or {\em brane} embedded in a higher-dimensional {\em bulk} spacetime. Ordinary matter fields are confined to the brane while the gravitational field can also propagate in the bulk, leading to modifications of Einstein's theory of general relativity at high energies. In particular, the Randall-Sundrum-type models are self-consistent and simple and allow for an investigation of the essential non-linear gravitational dynamics. The governing field equations induced on the brane differ from the general relativistic equations in that there are nonlocal effects from the free gravitational field in the bulk, transmitted via the projection of the bulk Weyl tensor, and the local quadratic energy-momentum corrections, which are significant in the high-energy regime close to the initial singularity. In this review we discuss the asymptotic dynamical evolution of spatially homogeneous brane-world cosmological models containing both a perfect fluid and a scalar field close to the initial singularity. Using dynamical systems techniques it is found that, for models with a physically relevant equation of state, an isotropic singularity is a past-attractor in all orthogonal spatially homogeneous models (including Bianchi type IX models). In addition, we describe the dynamics in a class of inhomogeneous brane-world models, and show that these models also have an isotropic initial singularity. These results provide support for the conjecture that typically the initial cosmological singularity is isotropic in brane-world cosmology.Comment: Einstein Centennial Review Article: to appear in CJ

    Complete remission in the nephrotic syndrome study network

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    Background and objectives This analysis from the Nephrotic Syndrome Study Network (NEPTUNE) assessed the phenotypic and pathology characteristics of proteinuric patients undergoing kidney biopsy and defined the frequency and factors associated with complete proteinuria remission (CRever). Design, setting, participants, & measurements We enrolled adults and children with proteinuria ≥0.5 g/d at the time of first clinically indicated renal biopsy at 21 sites in North America from April 2010 to June 2014 into a prospective cohort study. NEPTUNE central pathologists assigned participants to minimal-change disease (MCD), FSGS, membranous nephropathy, or other glomerulopathy cohorts. Outcome measures for this analysis were (1) CRever with urine protein-to-creatinine ratio (UPC)<0.3 g/g with preserved native kidney function and (2) ESRD. Continuous variables are reported as median and interquartile range (IQR; 25th, 75th percentile). Cox proportional hazards modeling was used to assess factors associated with CRever. Results We enrolled 441 patients: 116 (27%) had MCD, 142 (32%) had FSGS, 66 (15%) had membranous nephropathy, and 117 (27%) had other glomerulopathy. The baseline UPC was 4.1 g/g (IQR, 1.9, 7.7) and the eGFR was 81 ml/min per 1.73 m2 (IQR, 50, 105). Median duration of observation was 19 months (IQR, 11, 30). CRever occurred in 46% of patients, and 4.6% progressed to ESRD. Multivariate analysis demonstrated that higher prebiopsy proteinuria (hazard ratio, 0.3; 95% confidence interval, 0.2 to 0.5) and pathology diagnosis (FSGS versus MCD; hazard ratio, 0.2; 95% confidence interval, 0.1 to 0.5) were inversely associated with CRever. The effect of immunosuppressive therapy on remission varied by pathology diagnosis. Conclusions In NEPTUNE, the high frequency of other pathology in proteinuric patients affirms the value of the diagnostic kidney biopsy. Clinical factors, including level of proteinuria before biopsy, pathology diagnosis, and immunosuppression, are associated with complete remission

    Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

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    Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
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