Europa als "Wir" und "Nicht-Wir": Zum Europabild der polnischen Nationalkonservativen

Die in Polen seit November 2015 regierenden Nationalkonservativen haben ein gespaltenes Verhältnis zu Europa. Sie bejahen Europa als christliche Zivilisation, tun sich jedoch schwer mit der Europäischen Union, der sie Entwurzelung vorwerfen. Sie bekennen sich zu einer diffus verstandenen europäischen Kultur und Tradition einerseits und zeigen sich skeptisch gegenüber den politischen Strukturen, Eliten und liberalen Werten der Europäischen Union andererseits. Es liege nun an Polen, Europa an seine christlichen Traditionen zu erinnern. Polen sei ein Staat, der seinen Patriotismus und seinen Glauben hochhalte, und sei gleichsam aufgerufen, in Europa, insbesondere in seiner regionalen Nachbarschaft, eine entsprechende Rolle zu spielen. Das ambivalente Verhältnis der Nationalkonservativen zur europäischen Integration orientiert sich angesichts der im heutigen Europa unscharfen Identitäten an der vom Kommunismus konservierten Sehnsucht nach Grenzen, Vorgaben und der einen unumstößlichen Wahrheit

Heterogeneous distribution of Al-26 at the birth of the Solar System

It is believed that Al-26, a short-lived (t1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent Solar System with the initial Al-26/Al-27 ratio of ~5.2\times10-5, suggesting its external stellar origin. However, the stellar source of Al-26 and the manner in which it was injected into the solar system remain controversial: the Al-26 could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud or protoplanetary disk. Corundum (Al2O3) is thermodynamically predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from O-16-rich gas (Big Delta O-17 ~ -25%) of solar composition recorded heterogeneous distribution of Al-26 at the birth of the solar system: the inferred initial Al-26/Al-27 ratio ranges from ~6.5x10-5 to <2x10-6; ~50% of the corundum grains measured are Al-26-poor. Other Al-26-poor, O-16-rich refractory objects include grossite (CaAl4O7)- and hibonite(CaAl12O19)-rich calcium-aluminum-rich inclusions (CAIs) in CH chondrites, platy hibonite crystals in CM chondrites, and FUN (fractionation and unidentified nuclear isotopic anomalies) CAIs in CV, CO, and CR chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory O-16-rich solids in the solar system, we infer that Al-26 was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between Al-26 abundance and O-isotope compositions of corundum grains put important constraints on the stellar source of Al-26 in the solar system.Comment: Astrophysical Journal Letters 733, L3

The Case and Context for Atmospheric Methane as an Exoplanet Biosignature

Methane has been proposed as an exoplanet biosignature. Imminent observations with the James Webb Space Telescope may enable methane detections on potentially habitable exoplanets, so it is essential to assess in what planetary contexts methane is a compelling biosignature. Methane's short photochemical lifetime in terrestrial planet atmospheres implies that abundant methane requires large replenishment fluxes. While methane can be produced by a variety of abiotic mechanisms such as outgassing, serpentinizing reactions, and impacts, we argue that, in contrast to an Earth-like biosphere, known abiotic processes cannot easily generate atmospheres rich in CH$_4$ and CO$_2$ with limited CO due to the strong redox disequilibrium between CH$_4$ and CO$_2$. Methane is thus more likely to be biogenic for planets with 1) a terrestrial bulk density, high mean-molecular-weight and anoxic atmosphere, and an old host star; 2) an abundance of CH$_4$ that implies surface fluxes exceeding what could be supplied by abiotic processes; and 3) atmospheric CO$_2$ with comparatively little CO.Comment: 10 pages, 5 figures, 15 pages Supplementary Information, 3 Supplementary Figure

QUEST: A New Frontiers Uranus Orbiter Mission Concept Study

The ice giant planets, Uranus and Neptune, are fundamentally different from the gas giant and terrestrial planets. Though ice giants represent the most common size of exoplanet and possess characteristics that challenge our understanding of the way our solar system formed and evolved, they remain the only class of planetary object without a dedicated spacecraft mission. The inclusion of a Uranus orbiter as the third highest priority Flagship mission in the NASA Planetary Science Decadal Survey “Vision and Voyages for Planetary Science in the Decade 2013–2022” indicates a high level of support for exploration of the ice giants by the planetary science community. However, given the substantial costs associated with a flagship mission, it is critical to explore lower cost options if we intend to visit Uranus within an ideal launch window of 2029 - 2034 when a Jupiter gravity assist becomes available. In this paper, we describe the Quest to Uranus to Explore Solar System Theories (QUEST), a New Frontiers class Uranus orbiter mission concept study performed at the 30th Annual NASA/JPL Planetary Science Summer Seminar. The proposed QUEST platform is a spin-stabilized spacecraft designed to undergo highly elliptical, polar orbits around Uranus during a notional one-year primary science mission. The proposed major science goals of the mission are (1) to use Uranus as a natural laboratory to better understand the dynamos that drive magnetospheres in the solar system and beyond and (2) to identify the energy transport mechanisms in Uranus' magnetic, atmospheric, and interior environments in contrast with the other giant planets. With substantial mass, power, and cost margins, this mission concept demonstrates a compelling, feasible option for a New Frontiers Uranus orbiter mission

Size of the group IVA iron meteorite core: Constraints from the age and composition of Muonionalusta

The group IVA fractionally crystallized iron meteorites display a diverse range of metallographic cooling rates. These have been attributed to their formation in a metallic core, approximately 150 km in radius, that cooled to crystallization in the absence of any appreciable insulating mantle. Here we build upon this formation model by incorporating several new constraints. These include (i) a recent U-Pb radiometric closure age of <2.5 Myr after solar system formation for the group IVA iron Muonionalusta, (ii) new measurements and modeling of highly siderophile element compositions for a suite of IVAs, and (iii) consideration of the thermal effects of heating by the decay of the short-lived radionuclide 60Fe. Our model for the thermal evolution of the IVA core suggests that it was approximately 50 - 110 km in radius after being collisionally exposed. This range is due to uncertainties in the initial abundance of live 60Fe incorporated into the IVA core. Our models define a relationship between cooling rate and closure age, which is used to make several predictions that can be tested with future measurements. In general, our results show that diverse cooling rates and early U-Pb closure ages can only coexist on mantle-free bodies and that energy released by the decay of 60Fe reduces the core size necessary to produce diverse metallographic cooling rates. The influence of 60Fe on cooling rates has largely been neglected in previous core formation models; accounting for this heat source can affect size estimates for other iron meteorite cores that cooled to crystallization in the presence of live 60Fe. Candidates for such a scenario of early, mantle-free formation include the iron IIAB, IIIAB and IVB groups.Comment: 30 pages, 3 figures, accepted to Earth and Planetary Science Letter

Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns

The CM carbonaceous chondrites have all been aqueously altered, and some of them were subsequently heated in a parent body environment. Here we have sought to understand the impact of short duration heating on a highly aqueously altered CM through laboratory experiments on Allan Hills (ALH) 83100. Unheated ALH 83100 contains 83 volume per cent serpentine within the fine-grained matrix and altered chondrules. The matrix also hosts grains of calcite and dolomite, which are often intergrown with tochilinite, Fe(Ni) sulphides (pyrrhotite, pentlandite), magnetite and organic matter. Some of the magnetite formed by replacement of Fe(Ni) sulphides that were accreted from the nebula. Laboratory heating to 400 °C has caused partial dehydroxylation of serpentine and loss of isotopically light oxygen leading to an increase in bulk δ18O and fall in Δ17O. Tochilinite has decomposed to magnetite, whereas carbonates have remained unaltered. With regards to infrared spectroscopy (4000–400 cm-1; 2.5–25 µm), heating to 400 °C has resulted in decreased emissivity (increased reflectance), a sharper and more symmetric OH band at 3684 cm-1 (2.71 µm), a broadening of the Si—O stretching band together with movement of its minimum to longer wavenumbers, and a decreasing depth of the Mg—OH band (625 cm-1; 16 µm). The Si—O bending band is unmodified by mild heating. With heating to 800 °C the serpentine has fully dehydroxylated and recrystallized to ∼Fo60/70 olivine. Bulk δ18O has further increased and Δ17O decreased. Troilite and pyrrhotite have formed, and recrystallization of pentlandite has produced Fe,Ni metal. Calcite and dolomite were calcined at ∼700 °C and in their place is an un-named Ca-Fe oxysulphide. Heating changes the structural order of organic matter so that Raman spectroscopy of carbon in the 800 °C sample shows an increased (D1 + D4) proportional area parameter. The infrared spectrum of the 800 °C sample confirms the abundance of Fe-bearing olivine and is very similar to the spectrum of naturally heated stage IV CM Pecora Escarpment 02010. The temperature-related mineralogical, chemical, isotopic and spectroscopic signatures defined in ALH 83100 will help to track the post-hydration thermal histories of carbonaceous chondrite meteorites, and samples returned from the primitive asteroids Ryugu and Bennu

Developing the 60Fe-60Ni System for Early Solar System Chronology

Ph.D. University of Hawaii at Manoa 2015.Includes bibliographical references.This dissertation focuses on in situ Fe and Ni isotope analyses of chondrules from unequilibrated ordinary chondrites (UOCs) using the ion microprobe in order to constrain the initial 60Fe/56Fe ratio of UOC chondrules for early solar system chronology. Most of the chondrules analyzed for this dissertation do not have resolved excesses in 60Ni. A few chondrules have clear excesses in 60Ni (up to ~30‰) that can only be explained by the decay of 60Fe. However, the isochrons are clearly disturbed as shown by the weak correlation between the excesses in 60Ni and the Fe/Ni ratios. This, along with the discrepancies between the initial ratios inferred from bulk and in situ analyses, indicates that the Fe-Ni isotopic system in UOCs was disturbed. Synchrotron X-ray fluorescence maps of Fe and Ni and other trace elements in UOC chondrules confirm this. We found Fe and Ni enrichment along chondrule fractures, indicating extensive open system Fe-Ni redistribution occurred between chondrules and the surrounding matrix. These complications make the Fe-Ni isotope data difficult to interpret. Nevertheless, our data indicate that the initial 60Fe/56Fe ratio of UOC chondrules is between 5×10-8 and 2.6×10-7. Our ion microprobe measurements consist of counting Fe and Ni ions from a chondrule and calculating isotope ratios from those counts. However, ratios calculated this way are systematically higher than the true ratio in the sample. The bias increases proportionally with decreasing count rates of the normalizing isotope and can produce linear correlations similar to those of an isochron. This dissertation provides a detailed discussion of the influence of ratio bias on isochrons and it includes re-calculated ratios for several in situ studies, including most of the previously published in situ Fe-Ni data. Additionally, a study of the influence of ratio bias on in situ 26Al-26Mg (t1/2=0.7 Myr) systematics of plagioclase from H4 chondrites is included in this dissertation. We find that ratio bias is not significant for these analyses. We argue that the 26Al-26Mg ages for these chondrites date impact excavation and cooling at the surface of the H chondrite parent body, not cooling at depth as the onion shell model predicts

Data for: CALCITE AND DOLOMITE FORMATION IN THE CM PARENT BODY: INSIGHT FROM IN SITU C AND O ISOTOPE ANALYSES

This is the data for Table 1, Figures 6, 7 and 8 in the article CALCITE AND DOLOMITE FORMATION IN THE CM PARENT BODY: INSIGHT FROM IN SITU C AND O ISOTOPE ANALYSES

Ethnic Identities among Second-Generation Haitian Young Adults in Tampa Bay, Florida: An Analysis of the Reported Influence of Ethnic Organizational Involvement on Disaster Response after the Earthquake of 2010

Drawing upon 20 in-depth interviews with second generation Haitian young adults, I examined the ethnic identities and the involvement in ethnic organizations of the respondents. This study pays particular attention to how involvement in ethnic organizations influenced how the second generation Haitians believed the earthquake affected their identities and how they ultimately responded to the earthquake. Several of the findings revealed differences in how and why the respondents chose to ethnically identify such as Haitian, Haitian-American, black Haitian. The respondents\u27 choice to join an ethnic organization was driven by different desires but the perceived influence of the organization on their ethnic identities resulted in an increase in cultural knowledge as well as an ability to stay rooted in the culture. However, the lack of participation on the part of some of the respondents was a choice dictated by conflicts of authenticity, time, and responsibilities. The comparison between involved and non-involved respondents in terms of their response to the earthquake revealed that involved respondents were more active in volunteer projects. Involvement in ethnic organizations influenced how the second generation Haitians perceived the earthquake affected their identities, and ethnic affirmation in terms of a desire to visit Haiti was expressed by involved respondents. The implications of this study revealed the importance of establishing ethnic organizations in middle and high schools in order to foster a sense of pride through knowledge at an earlier age