Optical afterglow of the not so dark GRB 021211

We determine Johnson $B,V$ and Cousins $R,I$ photometric CCD magnitudes for the afterglow of GRB 021211 during the first night after the GRB trigger. The afterglow was very faint and would have been probably missed if no prompt observation had been conducted. A fraction of the so-called ``dark'' GRBs may thus be just ``optically dim'' and require very deep imaging to be detected. The early-time optical light curve reported by other observers shows prompt emission with properties similar to that of GRB 990123. Following this, the afterglow emission from $\sim 11$ min to $\sim 33$ days after the burst is characterized by an overall power-law decay with a slope $1.1\pm0.02$ in the $R$ passband. We derive the value of spectral index in the optical to near-IR region to be 0.6$\pm$0.2 during 0.13 to 0.8 day after the burst. The flux decay constant and the spectral slope indicate that optical observations within a day after the burst lies between cooling frequency and synchrotron maximum frequency.Comment: 4 pages, 2 figures, A&A Letters, 408, L2

Optical and near-infrared observations of the GRB 970616 error box

We report on near-infrared and optical observations of the GRB 970616 error box and of the X-ray sources discovered by ASCA and ROSAT in the region. No optical transient was found either within the IPN band or in the X-ray error boxes, similarly to other bursts, and we suggest that either considerable intrinsic absorption was present (like GRB 970828) or that the optical transient displayed a very fast decline (like GRB 980326 and GRB 980519).Comment: 2 pages with one encapsulated PostScript figure included. Uses Astronomy & Astrophysics LaTeX macros. Accepted for publication in Astronomy & Astrophysics Supplement Serie

Near-infrared follow-up to the May 2008 activation of SGR 1627-41

On 28 May 2008, the Swift satellite detected the first reactivation of SGR 1627-41 since its discovery in 1998. Following this event we began an observing campaign in near infrared wavelengths to search for a possible counterpart inside the error circle of this SGR, which is expected to show flaring activity simultaneous to the high energy flares or at least some variability as compared to the quiescent state. For the follow-up we used the 0.6m REM robotic telescope at La Silla Observatory, which allowed a fast response within 24 hours and, through director discretionary time, the 8.2m Very Large Telescope at Paranal Observatory. There, we observed with NACO to produce high angular resolution imaging with the aid of adaptive optics. These observations represent the fastest near infrared observations after an activation of this SGR and the deepest and highest spatial resolution observations of the Chandra error circle. 5 sources are detected in the immediate vicinity of the most precise X-ray localisation of this source. For 4 of them we do not detect variability, although the X-ray counterpart experimented a significant decay during our observation period. The 5th source is only detected in one epoch, where we have the best image quality, so no variability constrains can be imposed and remains as the only plausible counterpart. We can impose a limit of Ks > 21.6 magnitudes to any other counterpart candidate one week after the onset of the activity. Our adaptive optics imaging, with a resolution of 0.2" provides a reference frame for subsequent studies of future periods of activity.Comment: Accepted for publication in A&

Chemical and electrical properties of LSM cathodes prepared by mechanosynthesis

Mechanosynthesis of La1-xSrxMnO3 (x = 0, 0.25, 0.5, 0.75 and 1) was carried out at room temperature from stoichiometric mixtures of La2O3, Mn2O3 and SrO, obtaining monophasic powders with the perovskite structure. Physical properties of these materials and their chemical compatibility with the electrolyte yttria stabilized zirconia (YSZ), which depend strongly on the La/Sr ratio, were evaluated to corroborate availability to be implemented as cathode material in solid oxide fuel cells (SOFCs). Electrical conductivity values in air ranged between 100 and 400 S cm-1 in the temperature range of 25-850 C. Samples presented low reactivity with YSZ in the working temperature range (600-1000 C) maintaining the grain size small enough to preserve the catalytic activity for oxygen reduction.Gobierno de España MAT2010-1704

Aryl Hydrocarbon Receptor-Dependent inductions of omega-3 and omega-6 polyunsaturated fatty acid metabolism act inversely on tumor progression.

The Western diet contains a high ratio of omega-6 (ω6) to omega-3 (ω3) polyunsaturated fatty acids (PUFA). The prototypical aryl hydrocarbon receptor (AHR) ligand, 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), induces CYP1 family enzymes, which can metabolize PUFA to epoxides. Mice fed ω3-rich or ω6-rich diets were treated with TCDD and injected subcutaneously with AHR-competent Hepa1-GFP hepatoma cells or AHR-deficient LLC lung cancer cells. TCDD reduced the growth rates of the resulting tumors in ω3-fed mice and inhibited their metastasis to the liver and/or lung, but had the opposite effects in mice fed ω6 PUFA. These responses were likely attributable to the corresponding PUFA epoxides generated in tumor cells and/or host, since many depended upon co-administration of a soluble epoxide hydrolase (EPHX2) inhibitor in males, and/or were associated with increases in epoxide levels in tumors and sites of metastasis. Equivalent effects occurred in females in the absence of EPHX2 inhibition, probably because this sex expressed reduced levels of EPHX2. The responses elicited by TCDD were associated with effects on tumor vascularity, tumor cell proliferation and/or apoptosis. Thus environmental AHR agonists, and potentially also endogenous, nutritional, and microbiome-derived agonists, may reduce or enhance cancer progression depending on the composition of dietary PUFA, particularly in females

A photometricity and extinction monitor at the Apache Point Observatory

An unsupervised software ``robot'' that automatically and robustly reduces and analyzes CCD observations of photometric standard stars is described. The robot measures extinction coefficients and other photometric parameters in real time and, more carefully, on the next day. It also reduces and analyzes data from an all-sky $10 \mu m$ camera to detect clouds; photometric data taken during cloudy periods are automatically rejected. The robot reports its findings back to observers and data analysts via the World-Wide Web. It can be used to assess photometricity, and to build data on site conditions. The robot's automated and uniform site monitoring represents a minimum standard for any observing site with queue scheduling, a public data archive, or likely participation in any future National Virtual Observatory.Comment: accepted for publication in A