Optical absorption of divalent metal tungstates: Correlation between the band-gap energy and the cation ionic radius

We have carried out optical-absorption and reflectance measurements at room temperature in single crystals of AWO4 tungstates (A = Ba, Ca, Cd, Cu, Pb, Sr, and Zn). From the experimental results their band-gap energy has been determined to be 5.26 eV (BaWO4), 5.08 eV (SrWO4), 4.94 eV (CaWO4), 4.15 eV (CdWO4), 3.9-4.4 eV (ZnWO4), 3.8-4.2 eV (PbWO4), and 2.3 eV (CuWO4). The results are discussed in terms of the electronic structure of the studied tungstates. It has been found that those compounds where only the s electron states of the A2+ cation hybridize with the O 2p and W 5d states (e.g BaWO4) have larger band-gap energies than those where also p, d, and f states of the A2+ cation contribute to the top of the valence band and the bottom of the conduction band (e.g. PbWO4). The results are of importance in view of the large discrepancies existent in prevoiusly published data.Comment: 16 pages, 3 figures, 1 tabl

Maintaining excellent outcomes: the impact of age cutoff reclassification on reduced therapy for neuroblastoma patients

Survival; Neuroblastoma; Risk stratificationSupervivència; Neuroblastoma; Estratificació del riscSupervivencia; Neuroblastoma; Estratificación del riesgoThis work was funded by Instituto de Salud Carlos III through the projects “PI20/000530”, “ICI21000/76” (Co-funded by the European Regional Development Fund/European Social Fund; “A way to make Europe”/“Investing in your future”)

A Newtonian model for the WASP-148 exoplanetary system enhanced with TESS and ground-based photometric observations

The WASP-148 planetary system has a rare architecture with a transiting Saturn-mass planet on a tight orbit which is accompanied by a slightly more massive planet on a nearby outer orbit. Using new space-born photometry and ground-based follow-up transit observations and data available in literature, we performed modeling that accounts for gravitational interactions between both planets. Thanks to the new transit timing data for planet b, uncertainties of orbital periods and eccentricities for both planets were reduced relative to previously published values by a factor of 3-4. Variation in transit timing has an amplitude of about 20 minutes and can be easily followed-up with a 1-m class telescopes from the ground. An approximated transit ephemeris, which accounts for gravitational interactions with an accuracy up to 5 minutes, is provided. No signature of transits was found for planet c down to the Neptune-size regime. No other transiting companions were found down to a size of about 2.4 Earth radii for interior orbits. We notice, however, that the regime of terrestrial-size planets still remains unexplored in that system.Comment: Accepted for publication in Acta Astronomic

Applying an Indigenous methodology to a North–South, cross-cultural collaboration: successes and remaining challenges

This article represents our collective reflexivity in the process of applying an Indigenous methodology in a North–South, cross-cultural collaboration, funded through the British Government’s Global Challenges Research Fund. The projects’ aim was to bring together Bribri and Jakun leaders (from Costa Rica and Malaysia) for constructive dialogues about sustainable development. Specifically, we applied ulàpeitök (traditional form of Bribri collaboration and translates to lend [peitök] a hand), a concept of collaboration that honours family and community; we also used S-kṍpàkö, the Bribri word for conversation, a concept that translates to feeling the space around each other together. We analyse successes and challenges and elaborate on lessons learned including (a) how and why Indigenous collaboration and reciprocity should be understood before a project is planned or financed, (b) why western academic concepts of reciprocity (such as one-to-one exchanges) need to be decolonized to include Indigenous ways of relating to others, and (c) paying special attention to language in the co-writing of publications to avoid cultural misrepresentation. Our research can inform other North/South, Indigenous/non-Indigenous collaborations that aim to contribute to decolonizing research

Physical Structure of Small Wolf-Rayet Ring Nebulae

We have selected the seven most well-defined WR ring nebulae in the LMC (Br 2, Br 10, Br 13, Br 40a, Br 48, Br 52, and Br 100) to study their physical nature and evolutionary stages. New CCD imaging and echelle observations have been obtained for five of these nebulae; previous photographic imaging and echelle observations are available for the remaining two nebulae. Using the nebular dynamics and abundances, we find that the Br 13 nebula is a circumstellar bubble, and that the Br 2 nebula may represent a circumstellar bubble merging with a fossil main-sequence interstellar bubble. The nebulae around Br 10, Br 52, and Br 100 all show influence of the ambient interstellar medium. Their regular expansion patterns suggest that they still contain significant amounts of circumstellar material. Their nebular abundances would be extremely interesting, as their central stars are WC5 and WN3-4 stars whose nebular abundances have not been derived previously. Intriguing and tantalizing implications are obtained from comparisons of the LMC WR ring nebulae with ring nebulae around Galactic WR stars, Galactic LBVs, LMC LBVs, and LMC BSGs; however, these implications may be limited by small-number statistics. A SNR candidate close to Br 2 is diagnosed by its large expansion velocity and nonthermal radio emission. There is no indication that Br 2's ring nebula interacts dynamically with this SNR candidate.Comment: 20 pages, Latex (aaspp4.sty), 2 figures, accepted by the Astronomical Journal (March 99 issue

Insulin-like growth factor-I gene delivery to astrocytes reduces their inflammatory response to lipopolysaccharide

<p>Abstract</p> <p>Background</p> <p>Insulin-like growth factor-I (IGF-I) exerts neuroprotective actions in the central nervous system that are mediated at least in part by control of activation of astrocytes. In this study we have assessed the efficacy of exogenous IGF-I and IGF-I gene therapy in reducing the inflammatory response of astrocytes from cerebral cortex.</p> <p>Methods</p> <p>An adenoviral vector harboring the rat IGF-I gene and a control adenoviral vector harboring a hybrid gene encoding the herpes simplex virus type 1 thymidine kinase fused to <it>Aequorea victoria </it>enhanced green fluorescent protein were used in this study. Primary astrocytes from mice cerebral cortex were incubated for 24 h or 72 h with vehicle, IGF-I, the IGF-I adenoviral vector, or control vector; and exposed to bacterial lipopolysaccharide to induce an inflammatory response. IGF-I levels were measured by radioimmunoassay. Levels of interleukin 6, tumor necrosis factor-α, interleukin-1β and toll-like receptor 4 mRNA were assessed by quantitative real-time polymerase chain reaction. Levels of IGF-I receptor and IGF binding proteins 2 and 3 were assessed by western blotting. The subcellular distribution of nuclear factor κB (p65) was assessed by immunocytochemistry. Statistical significance was assessed by one way analysis of variance followed by the Bonferroni pot hoc test.</p> <p>Results</p> <p>IGF-I gene therapy increased IGF-I levels without affecting IGF-I receptors or IGF binding proteins. Exogenous IGF-I, and IGF-I gene therapy, decreased expression of toll-like receptor 4 and counteracted the lipopolysaccharide-induced inflammatory response of astrocytes. In addition, IGF-I gene therapy decreased lipopolysaccharide-induced translocation of nuclear factor κB (p65) to the cell nucleus.</p> <p>Conclusion</p> <p>These findings demonstrate efficacy of exogenous IGF-I and of IGF-I gene therapy in reducing the inflammatory response of astrocytes. IGF-I gene therapy may represent a new approach to reduce inflammatory reactions in glial cells.</p

A new radiative cooling curve based on an up to date plasma emission code

This work presents a new plasma cooling curve that is calculated using the SPEX package. We compare our cooling rates to those in previous works, and implement the new cooling function in the grid-adaptive framework `AMRVAC'. Contributions to the cooling rate by the individual elements are given, to allow for the creation of cooling curves tailored to specific abundance requirements. In some situations, it is important to be able to include radiative losses in the hydrodynamics. The enhanced compression ratio can trigger instabilities (such as the Vishniac thin-shell instability) that would otherwise be absent. For gas with temperatures below 10,000 K, the cooling time becomes very long and does not affect the gas on the timescales that are generally of interest for hydrodynamical simulations of circumstellar plasmas. However, above this temperature, a significant fraction of the elements is ionised, and the cooling rate increases by a factor 1000 relative to lower temperature plasmas.Comment: 11 pages, 6 figures. Typos fixed to match version on A&A 'forthcoming' website. Tables in text format online available at http://www.phys.uu.nl/~schure/coolin