Mid-Infrared Variability of protostars in IC 1396A

We have used Spitzer/IRAC to conduct a photometric monitoring program of the IC1396A dark globule in order to study the mid-IR (3.6 - 8 micron) variability of the heavily embedded Young Stellar Objects (YSOs) present in that area. We obtained light curves covering a 14 day timespan with a twice daily cadence for 69 YSOs, and continuous light curves with approximately 12 second cadence over 7 hours for 38 YSOs. Typical accuracies for our relative photometry were 1-2% for the long timespan data and a few mmag, corresponding to less than 0.5%, for the 7 hour continuous "staring-mode" data. More than half of the YSOs showed detectable variability, with amplitudes from ~0.05 mag to ~0.2 mag. About thirty percent of the YSOs showed quasi-sinusoidal light curve shapes with apparent periods from 5-12 days and light curve amplitudes approximately independent of wavelength over the IRAC bandpasses. We have constructed models which simulate the time dependent spectral energy distributions of Class I and I I YSOs in order to attempt to explain these light curves. Based on these models, the apparently periodic light curves are best explained by YSO models where one or two high latitude photospheric spots heat the inner wall of the circumstellar disk, and where we view the disk at fairly large inclination angle. Disk inhomogeneities, such as increasing the height where the accretion funnel flows to the stellar hotspot, enhances the light curve modulations. The other YSOs in our sample show a range of light curve shapes, some of which are probably due to varying accretion rate or disk shadowing events. One star, IC1396A-47, shows a 3.5 hour periodic light curve; this object may be a PMS Delta Scuti star

Rings and Halos in the Mid-Infrared: The Planetary Nebulae NGC 7354 and NGC 3242

We present images of the planetary nebulae (PNe) NGC 7354 and NGC 3242 in four mid-infrared (MIR) photometric bands centred at 3.6, 4.5, 5.8 and 8.0 microns; the results of observations undertaken using the Spitzer Space Telescope (SST). The resulting images show the presence of a halo and rings in NGC 3242, as previously observed through narrow band imaging at visual wavelengths, as well as evidence for a comparable halo and ring system in NGC 7354. This is the first time that a halo and rings have been observed in the latter source. We have analysed the formation of halos as a result of radiatively accelerated mass loss in the AGB progenitors. Although the models assume that dust formation occurs in C-rich environments, we note that qualitatively similar results would be expected for O-rich progenitors as well. The model fall-offs in halo density are found to result in gradients in halo surface brightness which are similar to those observed in the visible and MIR.Comment: 19 pages, 12 figures, Accepted for publication in MNRAS. 56 pages in arXi

Tratamiento con glucocorticoides en pacientes con inflamación relacionada a angiopatía amiloide cerebral: ¿qué tan útil son?

Objective. The objective of this review is to analyze the most recent evidence on the usefulness of glucocorticoids in patients with Inflammation Related to Cerebral Amyloid Angiopathy (IrCAA). Methods. Systematic review. A bibliographic search was carried out in the search engines and databases PubMed, ScienceDirect, Embase, EBSCO and MEDLINE databases, including any article related to the evaluation of the usefulness, efficacy or safety of glucocorticoids on inflammation of the cerebral amyloid angiopathy, would be included, giving priority to original studies and systematic reviews and meta-analyses. Results. It was found that the current evidence on its use is limited, deriving mainly from case reports, case series and retrospective studies. However, it seems that these agents cause a favorable response with partial resolution of the neurological manifestations immediately and/or progressively in the medium and long term, as well as abnormal imaging changes, given by vasogenic edema and cortical and subcortical microbleeds. although the improvement of the latter is not very marked. Conclusion. Current evidence on the use of glucocorticoids and their impact on clinical and neuroimaging outcomes is limited.Objetivo. El objetivo de esta revisión consiste en analizar la evidencia más reciente sobre la utilidad de los glucocorticoides en pacientes con Inflamación relacionada a Angiopatía Amiloide Cerebral (IrAAC). Métodos. Revisión sistemática. Se llevó a cabo una búsqueda bibliográfica en los motores de búsqueda y bases de datos bases de datos PubMed, ScienceDirect, Embase, EBSCO y MEDLINE, incluyendo cualquier artículo relacionado con la evaluación de la utilidad, eficacia o seguridad de los glucocorticoides sobre la inflamación de angiopatía amiloide cerebral, sería incluido, dando prioridad a los estudios originales y a las revisiones sistemáticas y meta-análisis. Resultados. Se encontró que, la evidencia actual sobre su uso es limitada, derivando principalmente de casos reporte, series de casos y estudios retrospectivos. No obstante, parece ser que estos agentes ocasionan una respuesta favorable con solución parcial de las manifestaciones neurológicas de manera inmediata y/o progresiva a mediano y largo plazo, así como de los cambios anormales imagenológicos, dados por edema vasogénico y microsangrados corticales y subcorticales, aunque la mejoría de este último, no es muy marcado. Conclusión. La evidencia actual sobre el uso de glucocorticoides y su impacto sobre desenlaces clínicos y neuroimagenológicos es limitada

Glucose-6-Phosphate Dehydrogenase Protects Escherichia coli from Tellurite-Mediated Oxidative Stress

The tellurium oxyanion tellurite induces oxidative stress in most microorganisms. In Escherichia coli, tellurite exposure results in high levels of oxidized proteins and membrane lipid peroxides, inactivation of oxidation-sensitive enzymes and reduced glutathione content. In this work, we show that tellurite-exposed E. coli exhibits transcriptional activation of the zwf gene, encoding glucose 6-phosphate dehydrogenase (G6PDH), which in turn results in augmented synthesis of reduced nicotinamide adenine dinucleotide phosphate (NADPH). Increased zwf transcription under tellurite stress results mainly from reactive oxygen species (ROS) generation and not from a depletion of cellular glutathione. In addition, the observed increase of G6PDH activity was paralleled by accumulation of glucose-6-phosphate (G6P), suggesting a metabolic flux shift toward the pentose phosphate shunt. Upon zwf overexpression, bacterial cells also show increased levels of antioxidant molecules (NADPH, GSH), better-protected oxidation-sensitive enzymes and decreased amounts of oxidized proteins and membrane lipids. These results suggest that by increasing NADPH content, G6PDH plays an important role in E. coli survival under tellurite stress

Selected Schizosaccharomyces pombe Strains Have Characteristics That Are Beneficial for Winemaking

At present, wine is generally produced using Saccharomyces yeast followed by Oenococus bacteria to complete malolactic fermentation. This method has some unsolved problems, such as the management of highly acidic musts and the production of potentially toxic products including biogenic amines and ethyl carbamate. Here we explore the potential of the fission yeast Schizosaccharomyces pombe to solve these problems. We characterise an extensive worldwide collection of S. pombe strains according to classic biochemical parameters of oenological interest. We identify three genetically different S. pombe strains that appear suitable for winemaking. These strains compare favourably to standard Saccharomyces cerevisiae winemaking strains, in that they perform effective malic acid deacidification and significantly reduce levels of biogenic amines and ethyl carbamate precursors without the need for any secondary bacterial malolactic fermentation. These findings indicate that the use of certain S. pombe strains could be advantageous for winemaking in regions where malic acid is problematic, and these strains also show superior performance with respect to food safety