Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia

Manufacturing of glass from tin mining tailings in Bolivia Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua,Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626º to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals

The ALMA Frontier Fields Survey

CONTEXT: Dusty star-forming galaxies are among the most prodigious systems at high redshift (z > 1), characterized by high star-formation rates and huge dust reservoirs. The bright end of this population has been well characterized in recent years, but considerable uncertainties remain for fainter dusty star-forming galaxies, which are responsible for the bulk of star formation at high redshift and thus play a key role in galaxy growth and evolution. AIMS: In this first paper of our series, we describe our methods for finding high redshift faint dusty galaxies using millimeter observations with ALMA. METHODS: We obtained ALMA 1.1 mm mosaic images for three strong-lensing galaxy clusters from the Frontier Fields Survey, which constitute some of the best studied gravitational lenses to date. The ≈2′ × 2′ mosaics overlap with the deep HST WFC3/IR footprints and encompass the high magnification regions of each cluster for maximum intrinsic source sensitivity. The combination of extremely high ALMA sensitivity and the magnification power of these clusters allows us to systematically probe the sub-mJy population of dusty star-forming galaxies over a large surveyed area. RESULTS: We present a description of the reduction and analysis of the ALMA continuum observations for the galaxy clusters Abell 2744 (z = 0.308), MACS J0416.1-2403 (z = 0.396) and MACS J1149.5+2223 (z = 0.543), for which we reach observed rms sensitivities of 55, 59 and 71 μJy beam-1 respectively. We detect 12 dusty star-forming galaxies at S/N ≥ 5.0 across the three clusters, all of them presenting coincidence with near-infrared detected counterparts in the HST images. None of the sources fall close to the lensing caustics, thus they are not strongly lensed. The observed 1.1 mm flux densities for the total sample of galaxies range from 0.41 to 2.82 mJy, with observed effective radii spanning ≲0.̋05 to 0.̋37 ± 0.̋21 . The lensing-corrected sizes of the detected sources appear to be in the same range as those measured in brighter samples, albeit with possibly larger dispersion

Tunneling dynamics in exactly-solvable models with triple-well potentials

Inspired by new trends in atomtronics, cold atoms devices and Bose-Einstein condensate dynamics, we apply a general technique of N=4 extended Supersymmetric Quantum Mechanics to isospectral Hamiltonians with triple-well potentials, i.e. symmetric and asymmetric. Expressions of quantum-mechanical propagators, which take into account all states of the spectrum, are obtained, within the N = 4 SQM approach, in the closed form. For the initial Hamiltonian of a harmonic oscillator, we obtain the explicit expressions of potentials, wavefunctions and propagators. The obtained results are applied to tunneling dynamics of localized states in triple-well potentials and for studying its features. In particular, we observe a Josephson-type tunneling transition of a wave packet, the effect of its partial trapping and a non-monotonic dependence of tunneling dynamics on the shape of a three-well potential. We investigate, among others, the possibility of controlling tunneling transport by changing parameters of the central well, and we briefly discuss potential applications of this aspect to atomtronic devices.Comment: Latex, 28 pages, 7 Figs, 2 Tables; minor presentation changes, journal versio

Speciation of common Gram-negative pathogens using a highly multiplexed high resolution melt curve assay

The identification of the bacterial species responsible for an infection remains an important step for the selection of antimicrobial therapy. Gram-negative bacteria are an important source of hospital and community acquired infections and frequently antimicrobial resistant. Speciation of bacteria is typically carried out by biochemical profiling of organisms isolated from clinical specimens, which is time consuming and delays the initiation of tailored treatment. Whilst molecular methods such as PCR have been used, they often struggle with the challenge of detecting and discriminating a wide range of targets. High resolution melt analysis is an end-point qPCR detection method that provides greater multiplexing capability than probe based methods. Here we report the design of a high resolution melt analysis assay for the identification of six common Gram-negative pathogens; Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa, Salmonella Sp, and Acinetobacter baumannii, and a generic Gram-negative specific 16S rRNA control. The assay was evaluated using a well characterised collection of 113 clinically isolated Gram-negative bacteria. The agreement between the HRM assay and the reference test of PCR and sequencing was 98.2% (Kappa 0.96); the overall sensitivity and specificity of the assay was 97.1% (95% CI: 90.1–99.7%) and 100% (95% CI: 91.78–100%) respectively

The ALMA Frontier Fields Survey. II. Multiwavelength Photometric analysis of 1.1 mm continuum sources in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223

CONTEXT: The Hubble and Spitzer Space Telescope surveys of the Frontier Fields provide extremely deep images around six massive, strong-lensing clusters of galaxies. The ALMA Frontier Fields survey aims to cover the same fields at 1.1 mm, with maps reaching (unlensed) sensitivities of <70 μJy, in order to explore the properties of background dusty star-forming galaxies. AIMS: We report on the multi-wavelength photometric analysis of all 12 significantly detected (>5σ) sources in the first three Frontier Fields clusters observed by ALMA, based on data from Hubble and Spitzer, the Very Large Telescope and the Herschel Space Observatory. METHODS: We measure the total photometry in all available bands and determine the photometric redshifts and the physical properties of the counterparts via SED-fitting. In particular, we carefully estimate the far-infrared (FIR) photometry using 1.1 mm priors to limit the misidentification of blended FIR counterparts, which strongly affect some flux estimates in previous FIR catalogs. Due to the extremely red nature of these objects, we used a large range of parameters (e.g. 0.0 <Av< 20.0) and templates (including AGNs and ULIRGs models). RESULTS: We identify robust near-infrared (NIR) counterparts for all 11 sources with Ks detection, the majority of which are quite red, with eight having F814W − Ks ≳ 4 and five having F160W − [ 4.5 ] ≳ 3. From the FIR point of view, all our objects have zphot ~ 1–3, whereas based on the optical SED one object prefers a high-z solution (z ≥ 7). Five objects among our sample have spectroscopic redshifts from the GLASS survey for which we can reproduce their SEDs with existing templates. This verification confirms the validity of our photometric redshift methodology. The mean redshift of our sample is zphot = 1.99 ± 0.27. All 1.1 mm selected objects are massive (10.0 < log  [ M⋆(M⊙) ] < 11.5), with high star formation rates (⟨ log [ SFR(M⊙/ yr) ] ⟩ ≈ 1.6) and high dust contents (8.1 < log  [ Mdust(M⊙) ] < 8.8), consistent with previous ALMA surveys

Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor.

Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods

Caracterização e avaliação dos usos educacionais das TIC em 10 seqüências de ensino secundário na história

This study describes and characterizes the educational use of ICT in ten didactic sequences of teaching history classes in high school, as well as, the extent in which this educational uses may be considered innovative of the typical processes of teaching and learning history. The approach taken for the didactics sequence analysis is by identifying teaching performance segments (SAD). Main results show, in the didactic sequences, the presence of 13 types of ICT use; 4 in relation to the use of the teacher and seven to the students'. In conclusion, didactic sequences exhibit little diversity in the use of ICT practices associated to an essentially transmissive approach to teaching and preferably used by students. &nbsp;El estudio describe y caracteriza el uso educativo de TIC en diez Secuencias Didácticas de clases de historia en enseñanza secundaria, así como el grado en que los usos educativos caracterizados pueden considerarse innovadores de los procesos típicos de enseñanza y aprendizaje de la historia. El enfoque asumido para el análisis de las Secuencias Didácticas es mediante la identificación de segmentos de actuación docente (SAD). Los principales resultados muestran en las secuencias didácticas la presencia de 13 tipos de uso de TIC, 4 en relación al uso del profesor y 7 usos de los estudiantes. En conclusión, se exhiben secuencias didácticas con poca diversidad en el uso de las TIC, esencialmente prácticas asociadas a un enfoque transmisivo de la enseñanza y, preferentemente, utilizadas por los estudiantes. &nbsp;Este estudo descreve e caracteriza a utilização educativa das TIC em dez sequências didáticas de ensino nas aulas de história e até que ponto os usos educacionais podem ser considerados inovadores nos processos típicos de ensino e aprendizagem da história. A abordagem adoptada para a análise da sequéncia de ensino é feita através da identificação de segmentos de atuação docente (SAD). Os principais resultados mostram nas sequências didáticas, a presenga de 13 tipos de utilização das TIC, 4 em relação ao uso do professor e sete em relação aos usos dos alunos. Em conclusão, as sequências didáticas estudadas apresentam pouca diversidade na utilização de práticas com uso das TIC, práticas associadas ao abordagem essencialmente transmissivo de ensino e de preferencia usado pelos alunos. &nbsp

La irrupción del marketing como estrategia para capturar estudiantes: publicidad y avisaje en la educación superior chilena

El present estudi realitza una anàlisi empírica i comparativa de la inversió publicitària en els mitjans de comunicació realitzada per les universitats xilenes amb dades de l'any 2010. La publicitat en els mitjans és important en la construcció del capital simbòlic que concentra elements del que Weber anomena com prestigi. La introducció del sistema de mercat en l'educació superior xilena quantifica el prestigi institucional segons la seva ubicació en el rànquing d'universitats. Així, aquest instrument quantitatiu és utilitzat per captar estudiants i realimentar la construcció o el manteniment del capital simbòlic. Les universitats realitzen despeses en publicitat via cotractació d'avisos en els mitjans de premsa, intentant no només demostrar, sinó subvencionar la manca de prestigi. Sota aquest marc, es va realitzar una correlació entre qualitat universitària, distribució d'ingressos pressupostaris de les universitats i les despeses efectuades en campanyes publicitaries, observant diversos comportaments: des d'universitats que no utilitzen els mitjans, fins a altres que li destinen sumes quantioses. També es descriu aquesta despesa en relació al capital de prestigi de cada institució. Atrau l'atenció que institucions amb baix capital simbòlic realitzin altes despeses en publicitat. L'anàlisi de desigualtat, usant l'índex de Gini, mostra una marcada disparitat entre les xifres financeres invertides per les institucions analitzades.This article provides an empirical and comparative analysis of the investment in media publicity made by institutions of the Chilean Higher Education system. The data corresponds to the year 2010. As Weber has described, in the construction of institutional prestige, media publicity investment is an important component of symbolic capital. The construction of institutional prestige using symbolic traditional excellence or accelerated growth is related to the marketing of institutions. The introduction of marketing in Chilean higher education quantifies institutional prestige through the use of rankings and also through the financial profits obtained from students’ fees. Some universities attempt to cultivate “artificial” prestige through the use of marketing in the media instead of producing truly symbolic capital. In this framework, the article correlates university quality, financial resources and media expenditure. We observe different types of institutional behaviour, noting that in practical terms some institutions attribute only minor importance to marketing while others make a substantial investment. We postulate an inverse correlation between this type of expenditure and symbolic capital. An analysis of the distribution of expenditures with the Gini index shows a clear imbalance between the institutions.El presente estudio realiza un análisis empírico y comparativo de la inversión publicitaria en medios realizada por las universidades chilenas con datos del año 2010. El avisaje en medios es importante en la construcción del capital simbólico que concentra elementos de lo que Weber menciona como prestigio.  La introducción del sistema de mercado en la educación superior chilena cuantifica el prestigio institucional por su ubicación en el ranking de universidades. Así, este instrumento cuantitativo es usado para captar estudiantes y retroalimentar la construcción o el mantenimiento del capital simbólico. Las universidades realizan gastos en publicidad vía avisaje, intentando no solo demostrar, sino subvencionar la falta de prestigio. Bajo este marco, se realizó una correlación entre calidad universitaria, distribución de ingresos presupuestarios de las universidades y gastos efectuados en avisaje, observándose variados comportamientos: desde universidades que no lo utilizan, hasta otras que le destinan montos apreciables. También se describe este gasto en relación con el capital de prestigio de cada institución. Llama la atención que instituciones con bajo capital simbólico realicen un alto gasto en medios. El análisis de desigualdad, usando el índice de Gini, muestra una marcada disparidad en la inversión financiera utilizada por las instituciones analizada

Mineralogical and thermal characterization of borate minerals from Rio Grande deposit, Uyuni (Bolivia)

Large volumes of borate resources exist in Bolivia, with the most important being the Rio Grande deposit, located close to the Salar of Uyuni. Here, borates occur in beds and lenses of variable thickness. A mineralogical and thermal characterization of borates from the Rio Grande was made using XRD, FTIR, SEM and DTA TG. The deposit is mainly composed of B2O3, CaO and Na2O, with minor contents of MgO and K2O. Some outcrops are constituted by pure ulexite aggregates (NaCaB5 O6(OH)6 5H2O) of fibrous morphology; in other cases, gypsum, calcite and halite also are present. The thermal decomposition of ulexite begins at 70 C and proceeds up to *550 C; this decomposition is attributed to dehydration and dehydroxylation processes in three steps: at 115, 150 300 and 300 550 C. The last mass loss of 1 5 % at 800 C is due to the removal of Cl2 from the decomposition of halite. DTA shows two endothermic events related to the removal of water; in the first, NaCaB5O6(OH)6 5H2O evolved from NaCaB5O6(OH)6 3H2O, at 108 116 C; in the second, NaCaB5O6(OH)6 is formed at 180 185 C and NaCaB5O9 (amorphous) is formed at 300 550 C. The exothermic peak (658 720 C) is related to the crystallization of NaCaB5O9. A small endothermic peak appears due to the halite melting. Later, another endothermic event (821 877 C) appears, which is related to the decomposition of NaCaB5O9 into a crystalline phase of CaB2O4 and amorphous NaB3O5. The XRD pattern evidences that, at 1050 C, CaB2O4 still remains in the crystalline state