309 research outputs found

    Degradación de rojo congo en un fotorreactor tubular de tecnología excimer. Estudio cinético

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    Como ampliación al estudio realizado sobre la fotodegradación de rojo congo con lámparas discontinuas de tecnologíaexcimer de XeBr, KrCl y Cl2, en este trabajo se ha estudiado la fotodegradación de dicho colorante mediante un fotorreactor continuo de KrCl, con recirculación, con H2O2 y con reactivo Fenton. Del estudio de la influencia de las condiciones de operación, se han seleccionado los valores de caudal y de concentración inicial de rojo congo óptimos para su degradación. Adicionalmente, se ha comprobado que la degradación de rojo congo mejora al aumentar la cantidad de H2O2 adicionada al medio hasta una relación molar H2O2: rojo congo de 75:1 a partir de la cual ya no aumenta más. Además, la fotodegradación de rojo congo también se ve favorecida al aumentar la concentración de Fe2+ al utilizar el reactivo Fenton.El modelo modificado de pseudo primer orden propuestopreviamente se ha aplicado a este tipo de reactor. Delajuste del modelo, se ha obtenido la tendencia de la constantede velocidad (k), para las diferentes series experimentales.Además, los valores calculados con el modelopara la conversión de rojo congo se han comparado conlos experimentales, obteniéndose un buen ajuste lineal.Finalmente, se ha realizado un análisis ANOVA confirmándosela validez del modelo

    Fine mapping and single nucleotide polymorphism effects estimation on pig chromosomes 1, 4, 7, 8, 17 and X

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    Fine mapping of quantitative trait loci (QTL) from previous linkage studies was performed on pig chromosomes 1, 4, 7, 8, 17, and X which were known to harbor QTL. Traits were divided into: growth performance, carcass, internal organs, cut yields, and meat quality. Fifty families were used of a F2 population produced by crossing local Brazilian Piau boars with commercial sows. The linkage map consisted of 237 SNP and 37 microsatellite markers covering 866 centimorgans. QTL were identified by regression interval mapping using GridQTL. Individual marker effects were estimated by Bayesian LASSO regression using R. In total, 32 QTL affecting the evaluated traits were detected along the chromosomes studied. Seven of the QTL were known from previous studies using our F2 population, and 25 novel QTL resulted from the increased marker coverage. Six of the seven QTL that were significant at the 5% genome-wide level had SNPs within their confidence interval whose effects were among the 5% largest effects. The combined use of microsatellites along with SNP markers increased the saturation of the genome map and led to smaller confidence intervals of the QTL. The results showed that the tested models yield similar improvements in QTL mapping accuracy

    Progressive transformation of a flux rope to an ICME

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    The solar wind conditions at one astronomical unit (AU) can be strongly disturbed by the interplanetary coronal mass ejections (ICMEs). A subset, called magnetic clouds (MCs), is formed by twisted flux ropes that transport an important amount of magnetic flux and helicity which is released in CMEs. At 1 AU from the Sun, the magnetic structure of MCs is generally modeled neglecting their expansion during the spacecraft crossing. However, in some cases, MCs present a significant expansion. We present here an analysis of the huge and significantly expanding MC observed by the Wind spacecraft during 9 and 10 November, 2004. After determining an approximated orientation for the flux rope using the minimum variance method, we precise the orientation of the cloud axis relating its front and rear magnetic discontinuities using a direct method. This method takes into account the conservation of the azimuthal magnetic flux between the in- and out-bound branches, and is valid for a finite impact parameter (i.e., not necessarily a small distance between the spacecraft trajectory and the cloud axis). Moreover, using the direct method, we find that the ICME is formed by a flux rope (MC) followed by an extended coherent magnetic region. These observations are interpreted considering the existence of a previous larger flux rope, which partially reconnected with its environment in the front. These findings imply that the ejected flux rope is progressively peeled by reconnection and transformed to the observed ICME (with a remnant flux rope in the front part).Comment: Solar Physics (in press

    Guidelines for incorporating scientific knowledge and practice on rare diseases into higher education: neuronal ceroid lipofuscinoses as a model disorder model disorder.

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    This article addresses the educational issues associated with rare diseases (RD) and in particular the Neuronal Ceroid Lipofuscinoses (NCLs, or CLN diseases) in the curricula of Health Sciences and Professional's Training Programs. Our aim is to develop guidelines for improving scientific knowledge and practice in higher education and continuous learning programs. Rare diseases (RD) are collectively common in the general populationwith 1 in 17 people affected by a RDin their lifetime. Inherited defects in genes involved in metabolism are the commonest group of RD with over 8000 known inborn errors of metabolism. The majority of these diseases are neurodegenerative including the NCLs. Any professional training program on NCL must take into account the medical, social and economic burdens related to RDs. To address these challenges and find solutions to themit is necessary that individuals in the government and administrative authorities, academia, teaching hospitals and medical schools, the pharmaceutical industry, investment community and patient advocacy groups all work together to achieve these goals. The logistical issues of including RD lectures in university curricula and in continuing medical education should reflect its complex nature. To evaluate the state of education in the RD field, a summary should be periodically up dated in order to assess the progress achieved in each country that signed up to the international conventions addressing RD issues in society. It is anticipated that auditing current practice will lead to higher standards and provide a framework for those educators involved in establishing RD teaching programs world-wide.publishedVersio

    Role of dipolar and exchange interactions in the positions and widths of EPR transitions for the single-molecule magnets Fe8 and Mn12

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    We examine quantitatively the temperature dependence of the linewidths and line shifts in electron paramagnetic resonance experiments on single crystals of the single-molecule magnets Fe8_8 and Mn12_{12}, at fixed frequency, with an applied magnetic field along the easy axis. We include inter-molecular spin-spin interactions (dipolar and exchange) and distributions in both the uniaxial anisotropy parameter DD and the Land\'{e} gg-factor. The temperature dependence of the linewidths and the line shifts are mainly caused by the spin-spin interactions. For Fe8_8 and Mn12_{12}, the temperature dependence of the calculated line shifts and linewidths agrees well with the trends of the experimental data. The linewidths for Fe8_8 reveal a stronger temperature dependence than those for Mn12_{12}, because for Mn12_{12} a much wider distribution in DD overshadows the temperature dependence of the spin-spin interactions. For Fe8_8, the line-shift analysis suggests two competing interactions: a weak ferromagnetic exchange coupling between neighboring molecules and a longer-ranged dipolar interaction. This result could have implications for ordering in Fe8_8 at low temperatures.Comment: published versio

    Dislocation-induced spin tunneling in Mn-12 acetate

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    Comprehensive theory of quantum spin relaxation in Mn-12 acetate crystals is developed, that takes into account imperfections of the crystal structure and is based upon the generalization of the Landau-Zener effect for incoherent tunneling from excited energy levels. It is shown that linear dislocations at plausible concentrations provide the transverse anisotropy which is the main source of tunneling in Mn-12. Local rotations of the easy axis due to dislocations result in a transverse magnetic field generated by the field applied along the c-axis of the crystal, which explains the presence of odd tunneling resonances. Long-range deformations due to dislocations produce a broad distribution of tunnel splittings. The theory predicts that at subkelvin temperatures the relaxation curves for different tunneling resonances can be scaled onto a single master curve. The magnetic relaxation in the thermally activated regime follows the stretched-exponential law with the exponent depending on the field, temperature, and concentration of defects.Comment: 17 pages, 14 figures, 1 table, submitted to PR

    A complex systems approach to constructing better models for managing financial markets and the economy

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    We outline a vision for an ambitious program to understand the economy and financial markets as a complex evolving system of coupled networks of interacting agents. This is a completely different vision from that currently used in most economic models. This view implies new challenges and opportunities for policy and managing economic crises. The dynamics of such models inherently involve sudden and sometimes dramatic changes of state. Further, the tools and approaches we use emphasize the analysis of crises rather than of calm periods. In this they respond directly to the calls of Governors Bernanke and Trichet for new approaches to macroeconomic modelling.The publication of this work was partially supported by the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 284709, a Coordination and Support Action in the Information and Communication Technologies activity area (‘FuturICT’ FET Flagship Pilot Project). Doyne Farmer, Mauro Gallegati and Cars Hommes also acknowledge financial support from the EU-7th framework collaborative project “Complexity Research Initiative for Systemic InstabilitieS (CRISIS)”, grant No. 288501. Cars Hommes acknowledges financial support from the Netherlands Organization for Scientific Research (NWO), project “Understanding Financial Instability through Complex Systems”. None of the above are responsible for errors in this paper.Publicad

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

    Etravirine pharmacokinetics in HIV-infected pregnant women

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    __Background__ The study goal was to describe etravirine pharmacokinetics during pregnancy and postpartum in HIV-infected women. __Methods__ IMPAACT P1026s and PANNA are on-going, non-randomized, open-label, parallel-group, multi-center phase-IV prospective studies in HIV-infected pregnant women. Intensive steady-state 12-h pharmacokinetic profiles were performed from 2nd trimester through postpartum. Etravirine was measured at two labs using validated ultra performance liquid chromatography (detection limits: 0.020 and 0.026 mcg/mL). __Results__ Fifteen women took etravirine 200 mg twice-daily. Etravirine AUC0-12 was higher in the 3rd trimester compared to paired postpartum data by 34% (median 8.3 vs. 5.3 mcg*h/mL, p = 0.068). Etravirine apparent oral clearance was significantly lower in the 3rd trimester of pregnancy compared to paired postpartum data by 52% (median 24 vs. 38 L/h, p = 0.025). The median ratio of cord blood to maternal plasma concentration at delivery was 0.52 (range: 0.19-4.25) and no perinatal transmission occurred. __Conclusion__ Etravirine apparent oral clearance is reduced and exposure increased during the third trimester of pregnancy. Based on prior dose-ranging and safety data, no dose adjustment is necessary for maternal health but the effects of etravirine in utero are unknown. Maternal health and infant outcomes should be closely monitored until further infant safety data are available. __Clinical Trial registration:__ The IMPAACT protocol P1026s and PANNA study are registered at ClinicalTrials.gov under NCT00042289 and NCT00825929
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