The O VI Absorbers Toward PG0953+415: High Metallicity, Cosmic-Web Gas Far From Luminous Galaxies

The spectrum of the low-redshift QSO PG0953+415 shows two strong, intervening O VI absorption systems. To study the nature of these absorbers, we have used the Gemini Multiobject Spectrograph to conduct a deep spectroscopic galaxy redshift survey in the 5' x 5' field centered on the QSO. This survey is fully complete for r' < 19.7 and is 73% complete for r' < 21.0. We find three galaxies at the redshift of the higher-z O VI system (z = 0.14232) including a galaxy at projected distance rho = 155 kpc. We find no galaxies in the Gemini field at the redshift of the lower-z O VI absorber (z = 0.06807), which indicates that the nearest galaxy is more than 195 kpc away or has L < 0.04 L*. Previous shallower surveys covering a larger field have shown that the z = 0.06807 O VI absorber is affiliated with a group/filament of galaxies, but the nearest known galaxy has rho = 736 kpc. The z = 0.06807 absorber is notable for several reasons. The absorption profiles reveal simple kinematics indicative of quiescent material. The H I line widths and good alignment of the H I and metal lines favor photoionization and, moreover, the column density ratios imply a high metallicity: [M/H] = -0.3 +/- 0.12. The z = 0.14232 O VI system is more complex and less constrained but also indicates a relatively high metallicity. Using galaxy redshifts from SDSS, we show that both of the PG0953+415 O VI absorbers are located in large-scale filaments of the cosmic web. Evidently, some regions of the web filaments are highly metal enriched. We discuss the origin of the high-metallicity gas and suggest that the enrichment might have occurred long ago (at high z).Comment: Submitted for publication in the Astrophysical Journal Letters. Figs. 1 and 2 compressed for astro-ph. High-resolution version available at http://www.astro.umass.edu/~tripp/astro/qualitypreps/pg0953tripp.pd

Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars

Most of the successful physical theories rely on the constancy of few fundamental quantities (such as the speed of light, $c$, the fine-structure constant, \alpha, the proton to electron mass ratio, \mu, etc), and constraining the possible time variations of these fundamental quantities is an important step toward a complete physical theory. Time variation of \alpha can be accurately probed using absorption lines seen in the spectra of distant quasars. Here, we present the results of a detailed many-multiplet analysis performed on a new sample of Mg II systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in \alpha derived from our analysis over the redshift range 0.4<z<2.3 is \Delta\alpha/\alpha = (-0.06+/-0.06) x 10^{-5}. The median redshift of our sample (z=1.55) corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. This gives a 3\sigma limit, -2.5 x 10^{-16} yr^-1 <(\Delta\alpha/\alpha\Delta t) <+1.2x10^{-16} yr^-1, for the time variation of \alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.Comment: uses revtex, 4 pages 3 figures. Accepted for publication in Physical Review Letter

A new measurement of zinc metallicity in a DLA at z=3.35

We present chemical abundance measurements in the z_abs=3.35045 Damped Lyman-alpha (DLA) system observed in the UVES spectrum of the BAL quasar BR 1117-1329. We measure a neutral hydrogen column density N(HI)=6.9+/-1.7*10^{20} atoms/cm2 and derive mean abundances relative to solar: [Si/H] = -1.26+/-0.13, [Fe/H]=-1.51+/-0.13, [Ni/H]=-1.57+/-0.13, [Cr/H]=-1.36+/-0.13, [Zn/H]=-1.18+/-0.13, [Al/H]>-1.25, [O/H]>-1.25 and [N/H]3. The iron to zinc and chromium to zinc ratios, [Fe/Zn]=-0.33+/-0.05 and [Cr/Zn]=-0.18+/-0.05 demonstrate that the absorber has a low dust content. The nitrogen ratio [N/Si]<-0.98 suggests that the ``secondary'' N production process is taking place in this DLA. Finally, this absorber does not seem to present a convincing alpha-enhancement as shown by the alpha over Fe-peak element ratios: [Si/Fe]=0.25+/-0.06, [Si/Cr]=0.10+/-0.06 and [Si/Zn]=-0.08+/-0.06

Probing the variation of the fine-structure constant using QSO absorption lines

Search for the time variation of the fundamental constants is motivated by various unification theories. Here we present constraints on the variation of the fine-structure constant &#945;&#x2261;2/ &#x0127;c) obtained using UVES/VLT samples of QSO absorption systems. We find &lt; &#916;&#945;/&#945; &gt;w = (-0.06 &#177; 0.06) &#215; 10-5 using 23 Mg II systems and the many-multiplet (MM) method. Well selected 15 Si IV systems provide &lt; &#916;&#945;/&#945; &gt;w = (0.15 &#177; 0.43) &#215;10-5. Absence of detectable variation in &#945; is also confirmed by our new very high resolution (R ~ 100,000) observation of zabs = 1.1508 toward HE 0515-4414 using HARPS on the ESO 3.6m telescope

Probing the time-variation of the fine-structure constant: Results based on Si IV doublets from a UVES sample

We report a new constraint on the variation of the fine-structure constant based on the analysis of 15 Si IV doublets selected from a ESO-UVES sample. We find \Delta\alpha/\alpha = (+0.15+/-0.43) x 10^-5 over a redshift range of 1.59< z < 2.92 which is consistent with no variation in \alpha. This result represents a factor of three improvement on the constraint on \Delta\alpha/\alpha based on Si IV doublets compared to the published results in the literature. The alkali doublet method used here avoids the implicit assumptions used in the many-multiplet method that chemical and ionization inhomogeneities are negligible and isotopic abundances are close to the terrestrial value.Comment: 12 Pages, 7 figures. Accepted for publication in A&A. In addition to minor corrections an appendix is added in this revised versio

En la región del aire: obras de ficción en la prosa novohispana [RESEÑA]

Reseña de Barrera, Trinidad, coord. En la región del aire: obras de ficción en la prosa novohispana. Sevilla: Renacimiento, 2011. 293 pp. (ISBN: 978-84- 8472-661-6

Study of the effect of the concentration of hydrotalcite in the recovery of colorants in textile wastewater

[EN] The absorption capacity of calcined hydrotalcite at different concentrations in a solution of 0.05 g . L-1 of 4 different dyes has been compared; Direct Blue 199, Direct Red 23, Direct Blue 71 and Reactive Yellow. For this, the Lambert-Beer lines of each dye have been previously made. Two different concentrations of clay, 5 and 10 g . L-1, have been worked. Then the dye has been introduced into the clay by stirring for 24 hours in 100 ml of solution of each dye, to later filter it and allow to dry. In all cases, the absorption of the dye by the nanoclay has been almost absolute, leaving the initial solution very clean, which are excellent results from the point of view of cleaning wastewater. However, when obtaining very similar results when scaling it to an industrial production, it would be more optimal to use the lowest concentration in order to reduce costs. Finally, a color measurement was made using a Jasco V-670 spectrophotometer, double beam spectrophotometer between 190- 2700 nm and color differences are calculated and represented in a color chart. Again, no large differences are observed and reinforce the idea of using a low concentration.López, D.; Micó-Vicent, B.; Bonet-Aracil, M.; Bou-Belda, E. (2020). Study of the effect of the concentration of hydrotalcite in the recovery of colorants in textile wastewater. Annals of the University of Oradea: Fascicle of Textiles, Leatherwork (Online). 21(1):61-64. http://hdl.handle.net/10251/167210S616421

Antisymmetric-Tensor and Electromagnetic effects in an alpha'-non-perturbative Four-Dimensional String Cosmology

Starting from an exact (in the Regge slope alpha') functional method for a bosonic stringy sigma-model, we investigate four-dimensional cosmological string solutions in graviton, dilaton and antisymmetric tensor backgrounds, compatible with world-sheet conformal invariance, and valid beyond perturbative expansions in powers of alpha'. The antisymmetric tensor field, playing the role of an axion in the four-dimensional target space time, leads to spatial anisotropies of the emergent Robertson-Walker expanding Universe, and, upon coupling the system to the electromagnetic field, it results in non-trivial optical activity. Some estimates of the corresponding effects are made and their relevance to current cosmology is briefly discussed

Performance evaluation of an optical transparent access tier based on PON and spectral codes

The increasing amount of bandwidth requirements and quality of service needs for the next-generation access networks has boosted extensive research in the fiber-optics communication field. In this light, passive optical networks (PONs) combined with optical code division multiple access (OCDMA), provide a potentially cost-effective solution to meet such bandwidth demands. This work proposes an optical transparent architecture which enables all-optical communication between the network nodes. The encoded data streams are multiplexed at a merging point which results in multiple user interference (MUI), thus significantly reducing the network throughput. The networking nodes are able to monitor and record user activity in the PON, and further register the (past) state of activity at the merging point. In this work, we study the coherence of state between the networking nodes and the merging point, for different packet size distributions, in order to predict an optimal transmission instant of each node's data packets. We note that the states are coherent depending on the packet size distribution

The Optimal Concentration of Nanoclay Hydrotalcite for Recovery of Reactive and Direct Textile Colorants

[EN] Concerns about the health of the planet have grown dramatically, and the dyeing sector of the textile industry is one of the most polluting of all industries. Nanoclays can clean dyeing wastewater using their adsorption capacities. In this study, as a new finding, it was possible to analyze and quantify the amount of metal ions substituted by anionic dyes when adsorbed, and to determine the optimal amount of nanoclay to be used to adsorb all the dye. The tests demonstrated the specific amount of nanoclay that must be used and how to optimize the subsequent processes of separation and processing of the nanoclay. Hydrotalcite was used as the adsorbent material. Direct dyes were used in this research. X-ray diffraction (XRD) patterns allowed the shape recovery of the hydrotalcite to be checked and confirmed the adsorption of the dyes. An FTIR analysis was used to check the presence of characteristic groups of the dyes in the resulting hybrids. The thermogravimetric (TGA) tests corroborated the dye adsorption and the thermal fastness improvement. Total solar reflectance (TSR) showed increased radiation protection for UV-VIS-NIR. Through the work carried out, it has been possible to establish the maximum adsorption point of hydrotalcite.To the Vice-rectorate for research of the UPV for funding for open access charge: CRUEUniversitat Politecnica de Valencia.López-Rodríguez, D.; Micó-Vicent, B.; Bonet-Aracil, M.; Cases, F.; Bou-Belda, E. (2022). The Optimal Concentration of Nanoclay Hydrotalcite for Recovery of Reactive and Direct Textile Colorants. International Journal of Molecular Sciences. 23(17):1-24. https://doi.org/10.3390/ijms23179671124231