Citotoxicidad de suavizantes catiónicos sobre una línea celular establecida de mamífero.

Este articulo expone de forma detallada el proceso de determinación de la toxicidad de cuatro suavizantes catiónicos de uso textil, mediante técnicas in vitro con cultivos celulares. Se ha utilizado como parámetro de referencia el contenido total de proteinas.The determination of the toxicity of four textile cationic softeners are shown in this paper. In vitro technique with mammal cultured cells has been used and the quantity of total proteins has been measured.On expose le procédé pour la détermination de la toxicité de quatre tensoactives cationiques usés dans l'industrie textile. On mesure avec techniques in vitro avec cultures cellulaires le niveau de proteines totales.Peer Reviewe

AOX y medio ambiente.

Los productos organohalogenados son muy utilizados por la industria y su presencia en el medio ambiente está siendo controlada. En los últimos años se han desarrollado varias técnicas de detección, siendo desde finales de los 80 los AOX (adsorbable organic halogens) uno de los parámetros sobre los que se han realizado más estudios. En muchos paises de la Unión Europea y en E.E.U.U. de América, la presencia de compuestos organohalogenados en aguas continentales y suelos está legislada indicandose valores límite de AOX. En este trabajo se comentan los aspectos generales de la técnica, la utilidad del parámetro para el control de la calidad de aguas, sus ventajas y limitaciones, así como concentraciones detectadas en algunos sectores industriales.Halogenated organic compounds have found widespread used in industry and household, for that reason their presence in the environment have been controled since many years ago. Several detection techniques to know the presence of these compounds in the environment have been developed. AOX (Adsorbable Organic Halogens) has been one of the most used in the last years. Many countries of the European Union and U.S.A. have issued legislation about AOX. General aspects of this technique, utility of AOX as water quality parameter, advantages and levels in some industrial effluents are commented in this work.Les composés organohalogenés sont trés utilisés par l'industrie et leur présence dans l'environement est en train d'être controlé. Pendant les dérnierès annès, plusieurs techniques pour les detécter ont été developés. Un des parametres plus étudie a été le AOX ( Adsorbable Organic Halogen ). Dans beaucoup des pays de l'Europe Unie et E.E.U.U., la présence de composés organohalogenés dans l'eau continental et le sol est légiféré par valeurs de AOX. Dans ce travail, on comente sur les aspects generals de la technique, l'utilité de ce parametre pour le control de la qualité de l'eau, ses avantatges et limitations, de même que les concentrations detectés dans quelques secteurs industriels.Peer Reviewe

Absolute properties of the low-mass eclipsing binary CM Draconis

Spectroscopic and eclipsing binary systems offer the best means for determining accurate physical properties of stars, including their masses and radii. The data available for low-mass stars have yielded firm evidence that stellar structure models predict smaller radii and higher effective temperatures than observed, but the number of systems with detailed analyses is still small. In this paper we present a complete reanalysis of one of such eclipsing systems, CM Dra, composed of two dM4.5 stars. New and existing light curves as well as a radial velocity curve are modeled to measure the physical properties of both components. The masses and radii determined for the components of CM Dra are M1=0.2310+/-0.0009 Msun, M2=0.2141+/-0.0010 Msun, R1=0.2534+/-0.0019 Rsun, and R2=0.2396+/-0.0015 Rsun. With relative uncertainties well below the 1% level, these values constitute the most accurate properties to date for fully convective stars. This makes CM Dra a valuable benchmark for testing theoretical models. In comparing our measurements with theory, we confirm the discrepancies reported previously for other low-mass eclipsing binaries. These discrepancies seem likely to be due to the effects of magnetic activity. We find that the orbit of this system is slightly eccentric, and we have made use of eclipse timings spanning three decades to infer the apsidal motion and other related properties.Comment: 19 pages, 9 figures. Accepted for publication in Ap

Evaluación toxicológica de Metil paration, Metil Azinfós, Clorpirifos, Diazinón y Metamidofos, en camarones del género Penaeus Sp.

El objetivo principal de este trabajo es estudiar la letalidad de los Plaguicidas organofosforados: Metil Paratión, Metil Azinfós, Clorpirifos, Diazinón y Metamidofos, en camarones del género Penaeus sp. Se ha realizado una exposición a diferentes concentraciones de los compuestos, determinándose la CL50 (concentración que ocasiona e1 50 % de mortalidad) en un tratamiento agudo de 48 horas. Clorpirifos resultó ser el más tóxico con una CL50-48h de 0.0027 mg/l mientras que Metamidofos presentó la menor toxicidad con una CL50-48 h. de 5.132 mg/l.The main purpose of this work is to study the lethality of the pesticides Methyl Parathion, Methyl Azinfos, Chlorpyrifos, Diazinon and Methamidophos on shrimps of the genus Penaeus sp. exposed at diferent concentrations of these compounds; CL50 was determined (the one causing 50% of death rate) in an acute treatment of 48 hours. Results show that Chlorpyrifos is the most toxic (48h-LC50:0.0027 mg/l) and Methamidophos presented the lowest toxicity of al1 them (48h-LC50:5.132 mg/l).L'objectif principal de ce travail est d'étudier l'efficacité létale des anti-fléaux organophosphorés: Metil Paration, Metil Azinfos, Clorpirifos, Diazinon et Metamidofos, sur les crevettes du genre Penaeus sp. Les crevettes ont été exposées a différentes concentrations de composants, pour déterminer la CL50 (concentration qui provoque 50% de mortalité) pendant un traitement aigu de 48 heures. Clorpirifos a démontré être le plus toxique avec une LC50-48 h de 0,0027 mg/l, et Metamidofos le moins toxique avec une CL50-48 h de 5.132 mg/l.Peer Reviewe

Effects of cTBS on the Frequency-Following Response and Other Auditory Evoked Potentials

The frequency-following response (FFR) is an auditory evoked potential (AEP) that follows the periodic characteristics of a sound. Despite being a widely studied biosignal in auditory neuroscience, the neural underpinnings of the FFR are still unclear. Traditionally, FFR was associated with subcortical activity, but recent evidence suggested cortical contributions which may be dependent on the stimulus frequency. We combined electroencephalography (EEG) with an inhibitory transcranial magnetic stimulation protocol, the continuous theta burst stimulation (cTBS), to disentangle the cortical contribution to the FFR elicited to stimuli of high and low frequency. We recorded FFR to the syllable /ba/ at two fundamental frequencies (Low: 113 Hz; High: 317 Hz) in healthy participants. FFR, cortical potentials, and auditory brainstem response (ABR) were recorded before and after real and sham cTBS in the right primary auditory cortex. Results showed that cTBS did not produce a significant change in the FFR recorded, in any of the frequencies. No effect was observed in the ABR and cortical potentials, despite the latter known contributions from the auditory cortex. Possible reasons behind the negative results include compensatory mechanisms from the non-targeted areas, intraindividual variability of the cTBS effectiveness, and the particular location of our target area, the primary auditory cortex

Machine learning for the development of diagnostic models of decompensated heart failure or exacerbation of chronic obstructive pulmonary disease

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are two chronic diseases with the greatest adverse impact on the general population, and early detection of their decompensation is an important objective. However, very few diagnostic models have achieved adequate diagnostic performance. The aim of this trial was to develop diagnostic models of decompensated heart failure or COPD exacerbation with machine learning techniques based on physiological parameters. A total of 135 patients hospitalized for decompensated heart failure and/or COPD exacerbation were recruited. Each patient underwent three evaluations: one in the decompensated phase (during hospital admission) and two more consecutively in the compensated phase (at home, 30 days after discharge). In each evaluation, heart rate (HR) and oxygen saturation (Ox) were recorded continuously (with a pulse oximeter) during a period of walking for 6 min, followed by a recovery period of 4 min. To develop the diagnostic models, predictive characteristics related to HR and Ox were initially selected through classification algorithms. Potential predictors included age, sex and baseline disease (heart failure or COPD). Next, diagnostic classification models (compensated vs. decompensated phase) were developed through different machine learning techniques. The diagnostic performance of the developed models was evaluated according to sensitivity (S), specificity (E) and accuracy (A). Data from 22 patients with decompensated heart failure, 25 with COPD exacerbation and 13 with both decompensated pathologies were included in the analyses. Of the 96 characteristics of HR and Ox initially evaluated, 19 were selected. Age, sex and baseline disease did not provide greater discriminative power to the models. The techniques with S and E values above 80% were the logistic regression (S: 80.83%; E: 86.25%; A: 83.61%) and support vector machine (S: 81.67%; E: 85%; A: 82.78%) techniques. The diagnostic models developed achieved good diagnostic performance for decompensated HF or COPD exacerbation. To our knowledge, this study is the first to report diagnostic models of decompensation potentially applicable to both COPD and HF patients. However, these results are preliminary and warrant further investigation to be confirmed

GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory

We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low mass binary system with an orbital period of 0.77 days. Analysis of light- and radial velocity curves of the system yielded component masses of 0.38 +/- 0.02 and 0.28 +/- 0.02 Msol. The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1 sigma. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multi-band photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Halpha emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully-convective stellar interiors, where there are a limited number of precise measurements available in the literature.Comment: 14 pages, 5 figures, 10 tables, emulateapj format. Accepted for publication in Ap

Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b

Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, affecting their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-{\alpha} line in the far ultraviolet which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy we detect excess absorption in the helium triplet at 1083 nm during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measure line blue shifts of several km/s and post transit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form. [Additional notes by authors: Furthermore, we provide upper limits for helium signals in the atmospheres of the exoplanets HD 209458b, KELT-9b, and GJ 436b. We investigate the host stars of all planets with detected helium signals and those of the three planets we derive upper limits for. In each case we calculate the X-ray and extreme ultraviolet flux received by these planets. We find that helium is detected in the atmospheres of planets (orbiting the more active stars and) receiving the larger amount of irradiation from their host stars.]Comment: Submitted to Science on 14 March 2018; Accepted by Science on 16 November 2018; Published by Science on 6 December 2018. This is the author's version of the work. It is posted here by permission of the AAAS for personal use. The definitive version was published in Science, on 6 December 2018 - Report: pages 21 (preprint), 4 figures - Supplementary materials: 22 pages, 10 figures, 3 table

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

Proxima Centauri b is not a transiting exoplanet

We report Spitzer Space Telescope observations during predicted transits of the exoplanet Proxima Centauri b. As the nearest terrestrial habitable-zone planet we will ever discover, any potential transit of Proxima b would place strong constraints on its radius, bulk density, and atmosphere. Subsequent transmission spectroscopy and secondary-eclipse measurements could then probe the atmospheric chemistry, physical processes, and orbit, including a search for biosignatures. However, our photometric results rule out planetary transits at the 200~ppm level at 4.5$~{\mu}m$, yielding a 3$\sigma$ upper radius limit of 0.4~R_\rm{\oplus} (Earth radii). Previous claims of possible transits from optical ground- and space-based photometry were likely correlated noise in the data from Proxima Centauri's frequent flaring. Follow-up observations should focus on planetary radio emission, phase curves, and direct imaging. Our study indicates dramatically reduced stellar activity at near-to-mid infrared wavelengths, compared to the optical. Proxima b is an ideal target for space-based infrared telescopes, if their instruments can be configured to handle Proxima's brightness.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in MNRA