The Interstellar N/O Abundance Ratio: Evidence for Local Infall?

Sensitive measurements of the interstellar gas-phase oxygen abundance have revealed a slight oxygen deficiency ($\sim$ 15%) toward stars within 500 pc of the Sun as compared to more distant sightlines. Recent $FUSE$ observations of the interstellar gas-phase nitrogen abundance indicate larger variations, but no trends with distance were reported due to the significant measurement uncertainties for many sightlines. By considering only the highest quality ($\geq$ 5 $\sigma$) N/O abundance measurements, we find an intriguing trend in the interstellar N/O ratio with distance. Toward the seven stars within $\sim$ 500 pc of the Sun, the weighted mean N/O ratio is 0.217 $\pm$ 0.011, while for the six stars further away the weighted mean value (N/O = 0.142 $\pm$ 0.008) is curiously consistent with the current Solar value (N/O = 0.138$^{+0.20}_{-0.18}$). It is difficult to imagine a scenario invoking environmental (e.g., dust depletion, ionization, etc.) variations alone that explains this abundance anomaly. Is the enhanced nitrogen abundance localized to the Solar neighborhood or evidence of a more widespread phenomenon? If it is localized, then recent infall of low metallicity gas in the Solar neighborhood may be the best explanation. Otherwise, the N/O variations may be best explained by large-scale differences in the interstellar mixing processes for AGB stars and Type II supernovae.Comment: accepted for publication in the Astrophysical Journal Letter

Vergleich von Antibeschlagmethoden in der Endoskopie: Was wirklich hilft

Zusammenfassung: Hintergrund und Fragestellung: Endoskopische Verfahren, wie die fiberoptische Intubation, haben sich als Standard in der Anästhesie etabliert. Obwohl allgemein bekannt ist, dass zur sicheren Anwendung von Endoskopen eine Antibeschlagmethode unerlässlich ist, fehlen Studien zum Vergleich der Wirksamkeit verschiedener Antibeschlagmethoden. Ziel dieser Studie war es, die Wirksamkeit von 7Antibeschlagmethoden im Einsatz mit einem flexiblen und einem starren Endoskop zu untersuchen. Material und Methoden: Die Wirksamkeit von je 2Antibeschlaglösungen und -tüchern, einem induktiven Endoskopvorwärmer, sowie kontinuierlichem Sauerstofffluss über den Arbeitskanal der Optik wurde in einem Atemwegsmodell mithilfe eines flexiblen und eines starren Endoskops getestet sowie verblindet beurteilt. Ergebnisse: Insgesamt wurden 300Testbilder aufgezeichnet und analysiert. Sowohl in der Gruppe mit dem flexiblen als auch in der Gruppe mit dem starren Endoskop erzielten je eine Antibeschlaglösung und ein -tuch die besten Ergebnisse. Flexible Endoskopie: Anti-Fog (Versagerquote: 3%), Lina Clear (4%). Starre Endoskopie: Ultrastop (5%), Lina Clear (3,5%). Der Endoskopvorwärmer mit 2-maliger Anwendung zeigte in beiden Gruppen sehr gute Ergebnisse (6% und 10%). Keinen positiven Effekt gegen das Beschlagen eines Endoskops ergab die Verwendung des Sauerstoffflusses (93,5%). Schlussfolgerungen: Die Studie konnte aufzeigen, dass es Unterschiede in der Effektivität von Antibeschlagtüchern und -lösungen gibt. Der klinische Einsatz ist aber auch von weiteren Faktoren wie Endoskoptyp und Häufigkeit der Verwendung, Kosten- und Hygieneaspekten abhängig. Der induktive Endoskopvorwärmer kann trotz hoher Anschaffungskosten eine Alternative darstellen. Jedoch fehlen bislang klare Sicherheitshinweise zur mehrfachen Anwendung durch den Hersteller. Der kontinuierliche Sauerstofffluss über den Arbeitskanal einer flexiblen Optik kann nicht als Antibeschlagmethode empfohlen werde

Single-step electrodeposition of superhydrophobic black NiO thin films

International audienceBlack finished surfaces have extensive applications in many domains, such as optics, solar cells, and aerospace. The single step electrodeposition of superhydrophobic black NiO films from a dimethyl sulfoxide based electrolyte is described in this paper. The physicochemical properties of the obtained film were characterized using Scanning Electron Microscopy, X-ray Diffraction, and electrochemical tests (Electrochemical Impedance Spectroscopy and potentiodynamic polarization). A rough surface with a low reflection of light was formed after the deposition process that increased the contact angle of water from about 87º (for bare Cu) to 163º (in presence of the black coating), which improved the corrosion resistance of the Cu substrate by about 30%. The formed black NiO film revealed a notably high stability and kept its appearance even after corrosion tests

Slow, Steady-State Transport with "Loading" and Bulk Reactions: the Mixed Ionic Conductor La2_2CuO4+δ_{4+\delta}

We consider slow, steady transport for the normal state of the superconductor La$_2$CuO$_{4+\delta}$ in a one-dimensional geometry, with surface fluxes sufficiently general to permit oxygen to be driven into the sample (``loaded'') either by electrochemical means or by high oxygen partial pressure. We include the bulk reaction O$\to$O$^{2-}+2h$, where neutral atoms ($a$) go into ions ($i$) and holes ($h$). For slow, steady transport, the transport equations simplify because the bulk reaction rate density $r$ and the bulk loading rates $\partial_t n$ then are uniform in space and time. All three fluxes $j$ must be specified at each surface, which for a uniform current density $J$ corresponds to five independent fluxes. These fluxes generate two types of static modes at each surface and a bulk response with a voltage profile that varies quadratically in space, characterized by $J$ and the total oxygen flux $j_O$ (neutral plus ion) at each surface. One type of surface mode is associated with electrical screening; the other type is associated both with diffusion and drift, and with chemical reaction (the {\it diffusion-reaction mode}). The diffusion-reaction mode is accompanied by changes in the chemical potentials $\mu$, and by reactions and fluxes, but it neither carries current (J=0) nor loads the system chemically ($j_O=0$). Generation of the diffusion-reaction mode may explain the phenomenon of ``turbulence in the voltage'' often observed near the electrodes of other mixed ionic electronic conductors (MIECs).Comment: 11 pages, 1 figur

Dynamik von mikrobiellen Gemeinschaften in zeitweise überfluteten Böden mit und ohne Zugabe von Biokohle

Böden in Auen werden zeitweise überflutet, was eine Änderung des Redoxpotentials bewirkt. Diese variierenden Umweltbedingungen können Bodenmikroorganismen erheblichen Stress aussetzen, vor allem, wenn diese Schwankungen den physiologischen Toleranzbereich der Organismen überschreiten. Mikroorganismen setzen verschiedenste Anpassungs- und Vermeidungsstrategien ein, um in solchen Situationen überleben zu können. Hierdurch verändert sich die Zusammensetzung der bodenmikrobiellen Gemeinschaft, was wiederum Rückkopplungseffekte auf die biogeochemischen Eigenschaften des Bodens ausübt. Um Böden und deren Eigenschaften zu verbessern, werden seit einigen Jahren verschiedene Biokohlen eingesetzt. Welche bodenmikrobiellen Prozesse im Boden von der Biokohle auf welche Art beeinflusst werden, ist jedoch weitestgehend ungeklärt. Ziel dieser Studie war es, den Einfluss verschiedener Biokohlen und wechselnder Redoxverhältnisse auf die bodenmikrobielle Gemeinschaft in einem zeitweise überfluteten Boden zu untersuchen. Dazu wurden Bodenproben der Wupper mit unterschiedlichen Biokohlen im Laborversuch vermischt und vorinkubiert. Die eingesetzten Biokohlen BC200 und BC500 unterschieden sich in der Pyrolysetemperatur (200°C und 500°C). Die so vorbehandelten Böden wurden anschließend in biogeochemischen Mikrokosmen bei vordefinierten Redoxpotentialen inkubiert. Anschließend wurde die Dynamik der bodenmikrobiellen und der bakteriellen Gemeinschaft (PLFA und DGGE) bestimmt. Die Ergebnisse zeigen, dass sowohl die Änderung des Redoxpotentials, als auch die Zugabe von Biokohle die Zusammensetzung der mikrobiellen und bakteriellen Gemeinschaft in Bezug auf Gesamtzahl, aber auch nach taxonomischer Gruppe, verändern. Bestimmte mikrobielle Gruppen und Spezies werden gefördert bzw. unterdrückt. Möglicherweise lassen sich durch die Aufklärung dieser Zusammenhänge Vorhersagen zu Folgen bei Überflutungsereignissen treffen

The interpretive approach to religious education : challenging Thompson's interpretation

In a recent book chapter, Matthew Thompson makes some criticisms of my work, including the interpretive approach to religious education and the research and activity of Warwick Religions and Education Research Unit. Against the background of a discussion of religious education in the public sphere, my response challenges Thompson’s account, commenting on his own position in relation to dialogical approaches to religious education. The article rehearses my long held view that the ideal form of religious education in fully state funded schools of a liberal democracy should be ‘secular’ but not ‘secularist’; there should be no implication of an axiomatic secular humanist interpretation of religions

What is the Total Deuterium Abundance in the Local Galactic Disk?

Analyses of spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, together with spectra from the Copernicus and IMAPS instruments, reveal an unexplained very wide range in the observed deuterium/hydrogen (D/H) ratios for interstellar gas in the Galactic disk beyond the Local Bubble. We argue that spatial variations in the depletion of deuterium onto dust grains can explain these local variations in the observed gas-phase D/H ratios. We present a variable deuterium depletion model that naturally explains the constant measured values of D/H inside the Local Bubble, the wide range of gas-phase D/H ratios observed in the intermediate regime (log N(H I} = 19.2-20.7), and the low gas-phase D/H ratios observed at larger hydrogen column densities. We consider empirical tests of the deuterium depletion hypothesis: (i) correlations of gas-phase D/H ratios with depletions of the refractory metals iron and silicon, and (ii) correlation with the molecular hydrogen rotational temperature. Both of these tests are consistent with deuterium depletion from the gas phase in cold, not recently shocked, regions of the ISM, and high gas-phase D/H ratios in gas that has been shocked or otherwise heated recently. We argue that the most representative value for the total (gas plus dust) D/H ratio within 1 kpc of the Sun is >=23.1 +/- 2.4 (1 sigma) parts per million (ppm). This ratio constrains Galactic chemical evolution models to have a very small deuterium astration factor, the ratio of primordial to total (D/H) ratio in the local region of the Galactic disk, which we estimate to be f_d <= 1.19 +/-0.16 (1 sigma) or <= 1.12 +/- 0.14 (1 sigma) depending on the adopted light element nuclear reaction rates.Comment: 19 pages, 9 figure

Molecular tracers of PDR-dominated galaxies

Photon-dominated regions (PDRs) are powerful molecular line emitters in external galaxies. They are expected in galaxies with high rates of massive star formation due to either starburst (SB) events or starburst coupled with active galactic nuclei (AGN) events. We have explored the PDR chemistry for a range of physical conditions representing a variety of galaxy types. Our main result is a demonstration of the sensitivity of the chemistry to changes in the physical conditions. We adopt crude estimates of relevant physical parameters for several galaxy types and use our models to predict suitable molecular tracers of those conditions. The set of recommended molecular tracers differs from that which we recommended for use in galaxies with embedded massive stars. Thus, molecular observations can in principle be used to distinguish between excitation by starburst and by SB+AGN in distant galaxies. Our recommendations are intended to be useful in preparing Herschel and ALMA proposals to identify sources of excitation in galaxies.Comment: 18 pages, 6 figures, Accepted in Ap

Religion and religious education : comparing and contrasting pupils’ and teachers’ views in an English school

This publication builds on and develops the English findings of the qualitative study of European teenagers’ perspectives on religion and religious education (Knauth et al. 2008), part of ‘Religion in Education: A contribution to dialogue or a factor of conflict in transforming societies of European countries?’ (REDCo) project. It uses data gathered from 27 pupils, aged 15-16, from a school in a multicultural Northern town in England and compares those findings with data gathered from ten teachers in the humanities faculty of the same school, collected during research for the Warwick REDCo Community of Practice. Comparisons are drawn between the teachers’ and their pupils’ attitudes and values using the same structure as the European study: personal views and experiences of religion, the social dimension of religion, and religious education in school. The discussion offers an analysis of the similarities and differences in worldviews and beliefs which emerged. These include religious commitment/observance differences between the mainly Muslim-heritage pupils and their mainly non-practising Christian-heritage teachers. The research should inform the ways in which the statutory duties to promote community cohesion and equalities can be implemented in schools. It should also facilitate intercultural and interreligious understanding between teachers and the pupils from different ethnic and religious backgrounds