Space-based infrared interferometry to study exoplanetary atmospheres     

D. Defrère  A. Léger  O. Absil  C. Beichman  B. Biller  W. C. Danchi  K. Ergenzinger  C. Eiroa  S. Ertel  M. Fridlund  A. García Muñoz  M. Gillon  A. Glasse  M. Godolt  J. L. Grenfell  S. Kraus  L. Labadie  S. Lacour  R. Liseau  G. Martin  B. Mennesson  G. Micela  S. Minardi  S. P. Quanz  H. Rauer  S. Rinehart  N. C. Santos  F. Selsis  J. Surdej  F. Tian  E. Villaver  P. J. Wheatley  M. Wyatt 《Experimental Astronomy》2018,46(3):543-560

The quest for other habitable worlds and the search for life among them are major goals of modern astronomy. One way to make progress towards these goals is to obtain high-quality spectra of a large number of exoplanets over a broad range of wavelengths. While concepts currently investigated in the United States are focused on visible/NIR wavelengths, where the planets are probed in reflected light, a compelling alternative to characterize planetary atmospheres is the mid-infrared waveband (5–20 μm). Indeed, mid-infrared observations provide key information on the presence of an atmosphere, the surface conditions (e.g., temperature, pressure, habitability), and the atmospheric composition in important species such as H₂O, CO₂, O₃, CH₄, and N₂O. This information is essential to investigate the potential habitability of exoplanets and to make progress towards the search for life in the Universe. Obtaining high-quality mid-infrared spectra of exoplanets from the ground is however extremely challenging due to the overwhelming brightness and turbulence of the Earth’s atmosphere. In this paper, we present a concept of space-based mid-infrared interferometer that can tackle this observing challenge and discuss the main technological developments required to launch such a sophisticated instrument.  相似文献   

Transition from symmetry to asymmetry during continental rifting: an example from the Bight Basin–Terre Adélie (Australian and Antarctic conjugate margins)     

Nicolas Espurt  Jean‐Paul Callot  François Roure  Jennifer M. Totterdell  Heike I. M. Struckmeyer  Roland Vially 《地学学报》2012,24(3):167-180

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Fate of microbial biomass-derived amino acids in soil and their contribution to soil organic matter   总被引：2，自引：0，他引：2  

Anja Miltner  Reimo Kindler  Heike Knicker  Hans-Hermann Richnow  Matthias Kstner 《Organic Geochemistry》2009,40(9):978-985

Soil organic matter (SOM) is important for soil fertility and for the global C cycle. Previous studies have shown that during SOM formation no new compound classes are formed and that it consists basically of plant- and microorganism-derived materials. However, little data on the contribution from microbial sources are available. Therefore, we investigated previously in a model study the fate of C from ¹³C-labelled Gram-negative bacteria in soil (Kindler, R., Miltner, A. Richnow, H.H., Kästner, M., 2006. Fate of gram negative bacterial biomass in soil – mineralization and contribution to SOM. Soil Biology and Biochemistry 38, 2860–2870) and showed that 44% of the bulk ¹³C remained in the soil. Here we present the corresponding data on the fate of amino acids hydrolysed from proteins, which are the most abundant components of microbial biomass. After 224 days incubation, the label in the total amino acids in the soil amended with ¹³C-labelled cells decreased only to >95%. The total amino acids therefore clearly showed a lower turnover than the bulk ¹³C and a surprisingly stable concentration. Proteins therefore have to be considered as being stabilised in soil in dead, non-extractable biomass or cell fragments by known general stabilisation mechanisms. The label in the amino acids in a fraction highly enriched in living microbial biomass decreased to a greater extent, i.e. to 25% of the initially added amount. The amino acids removed from this fraction were redistributed via the microbial food web to non-living SOM. All amino acids in the microbial biomass were degraded at similar rates without a change in isotopic signature. The nuclear magnetic resonance (NMR) spectra of the soils were very similar and indicate that the residues of the degraded microbial biomass were very similar to those of the SOM and are a significant source for the formation of the SOM.  相似文献   

Egg capsule hatch rate and incubation duration of the California market squid,Doryteuthis (= Loligo) opalescens: insights from laboratory manipulations     

Louis D. Zeidberg  George Isaac  Chad L. Widmer  Heike Neumeister  William F. Gilly 《Marine Ecology》2011,32(4):468-479

Egg capsules of the squid Doryteuthis (= Loligo) opalescens were reared in the laboratory to assess the dependence of time‐to‐hatching (incubation time) and hatching success rate on temperature and light regime. Both incubation time and hatch duration were found to be inversely related to temperature. More than 96% of paralarvae hatch from eggs reared at temperatures between 9 and 14 °C. Hatch rate drops below 90% in warmer and colder water. No eggs hatch below 7 °C, and the upper limit of viability is near 25 °C. The vast majority (91%) of hatchlings emerged during the dark phase of the photoperiod. Egg capsules reared at 13.4 °C with a supposedly commensal polychaete, Capitella ovincola, had a slightly higher hatch rate than those without the annelid. Because eggs are naturally laid closely together, crowding was hypothesized to cause decreased ventilation and a lower hatch rate. Crowding was tested by placing two capsules (rather than one) into the small incubation chambers (50 ml). This treatment did not result in a lower hatch rate at 13.4 °C, but at 21.4 °C it decreased the hatch rate by 20%. Brood incubation duration is related to temperature by the equation: Incubation (days) = 14.97 + 177.40 × exp(?0.119 × Temperature –°C) (χ² = 282.5, P = 0.001). Stable isotope analysis confirmed that C. ovincola worms eat the capsule matrix, not the paralarvae. These polychaetes had a δ¹⁵N value of 12.79‰versus 12.06‰ for squid paralarvae, and 10.54‰ for the gelatinous matrix of egg capsules. This fractionation factor ε of 2.25‰ is consistent with marine food webs. Provision of nutrients and shelter for the annelids and increased hatch rate for the squid embryos suggests a symbiotic relationship between these organisms.  相似文献   

Marine benthic invertebrates from the Upper Jurassic of northern Ethiopia and their biogeographic affinities     

Wolfgang Kiessling  Dhirendra Kumar Pandey  Mena Schemm-Gregory  Heike Mewis  Martin Aberhan 《Journal of African Earth Sciences》2011,59(2-3):195-214

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The gas production of Comet 9P/Tempel 1 around the Deep Impact date     

M. Weiler  H. Rauer  J. Knollenberg 《Icarus》2007,190(2):423-431

The target of the Deep Impact space mission (NASA), Comet 9P/Tempel 1, was observed from two nights before impact to eight nights after impact using the FORS spectrographs at the ESO VLT UT1 and UT2 telescopes. Low resolution optical long-slit spectra were obtained to study the evolution of the gas coma around the Deep Impact event. Following first results of this observing campaign on the CN and dust activity [Rauer, H., Weiler, M., Sterken, C., Jehin, E., Knollenberg, J., Hainaut, O., 2006. Astron. Astrophys. 459, 257-263], this work presents a study of the complete dataset on CN, C₂, C₃, and NH₂ activity of Comet 9P/Tempel 1. An extended impact gas cloud was observed moving radially outwards. No compositional differences between this impact cloud and the undisturbed coma were found as far as the observed radicals are concerned. The gas production rates before and well after impact indicate no change in the cometary activity on an intermediate time scale. Over the observing period, the activity of Comet 9P/Tempel 1 was found to be related to the rotation of the cometary nucleus. The rotational lightcurve for different gaseous species provides indications for compositional differences among different parts of the nucleus surface.  相似文献   

Large-Scale Differences in Community Structure and Ecosystem Services of Eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis>) Beds Across Three Regions in Eastern Canada     

Mizuho Namba  Heike K. Lotze  Allison L. Schmidt 《Estuaries and Coasts》2018,41(1):177-192

Eelgrass (Zostera marina) forms extensive beds in temperate coastal and estuarine environments worldwide and provides important ecosystem services, including habitat for a wide range of species as well as nutrient cycling and carbon storage. However, little is known about how eelgrass ecosystem structure and services differ naturally among regions. Using large-scale field surveys, we examined differences in eelgrass bed structure, carbon and nitrogen storage, community composition, and habitat services across three distinct regions in Eastern Canada. We focused on eelgrass beds with low anthropogenic impacts to compare natural differences. In addition, we analyzed the relationships of eelgrass bed structure with environmental conditions, and species composition with bed structure and environmental conditions, to elucidate potential drivers of observed differences. Our results indicate that regional differences in eelgrass bed structure were weakly correlated with water column properties, whereas differences in carbon and nitrogen storage were mainly driven by differences in eelgrass biomass. There were distinct regional differences in species composition and diversity, which were particularly linked to temperature, as well as eelgrass bed structure indicating differences in habitat provision. Our results highlight natural regional differences in ecosystem structure and services which could inform spatial management and conservation strategies for eelgrass beds.  相似文献   

Whose neighbourhood is it? Ethnic diversity in urban spaces in Germany     

Heike Hanhörster 《GeoJournal》2000,51(4):329-338

This article focuses on the reciprocal effects that exist between the physical environment and the social interactions between ethno-cultural groups in disadvantaged neighbourhoods. Biographical narrative interviews and mental map analyses were carried out with German and Turkish residents in two disadvantaged neighbourhoods in Germany to define the resident's own experience of their physical surroundings.The findings of the research verify that the changes in the environment were not only physical and structural changes: they also led to changing identities having a symbolic meaning for the established German residents. As the Turkish residents work to create a sense of identity, the established residents view these changes more as a threat than as an enrichment. They do not so much feel threatened by the cultural differences between the groups, but they sense that their own `old-time' German socio-cultural position could be affected by the establishment of Turkisch residences and institutions in `their' neighbourhood. The empirical research revealed differences in the ethno-cultural perceptions between Duisburgh-Marxloh where there is a pronounced small-scale segregation between the groups, whereas there is a small-scale mix of different ethnic groups even at the block level in the other area investigated in Wuppertal-Osterbaum. Although both areas have a high percentage of ethnic minorities the small-scale mix in Wuppertal-Ostersbaum seems to have prevented a polarisation in the population.  相似文献   

Long-term Evolution of the Outgassing of Comet Hale-Bopp From Radio Observations   总被引：1，自引：0，他引：1  

Biver  N.  Bockelée-Morvan  D.  Colom  P.  Crovisier  J.  Germain  B.  Lellouch  E.  Davies  J. K.  Dent  W. R. F.  Moreno  R.  Paubert  G.  Wink  J.  Despois  D.  Lis  D. C.  Mehringer  D.  Benford  D.  Gardner  M.  Phillips  T. G.  Gunnarsson  M.  Rickman  H.  Winnberg  A.  Bergman  P.  Johansson  L. E. B.  Rauer  H. 《Earth, Moon, and Planets》1997,78(1-3):5-11

C/1995 O1 (Hale-Bopp) has been observed on a regular basis since August 1995 at millimetre and submillimetre wavelengths using IRAM, JCMT, CSO and SEST radio telescopes. The production rates of eight molecular species (CO, HCN, CH₃OH, H₂CO,H₂S, CS, CH₃CN,HNC) have been monitored as a function of heliocentric distance(r_h from 7 AU pre-perihelion to 4 AU post-perihelion. As comet Hale-Bopp approached and receded from the Sun, these species displayed different behaviours. Far from the Sun, the most volatile species were found in general relatively more abundant in the coma. In comparison to other species, HNC, H₂CO and CS showed a much steeper increase of the production rate with decreasing r_h. Less than 1.5 AU from the Sun, the relative abundances were fairly stable and approached those found in other comets near 1 AU. The kinetic temperature of the coma, estimated from the relative intensities of the CH₃OH and CO lines, increased with decreasing r_h, from about10 K at 7 AU to 110 K around perihelion. The expansion velocity of the gaseous species, derived from the line shapes, also increased with a law close tor_h ³. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Structural incorporation of Cm(III) in trioctahedral smectite hectorite: A time-resolved laser fluorescence spectroscopy (TRLFS) study     

Heike Brandt  Dirk Bosbach  Petra J. Panak 《Geochimica et cosmochimica acta》2007,71(1):145-154

Structural incorporation of the actinide curium in the octahedral layer of the trioctahedral Mg-rich smectite hectorite was studied using time-resolved laser fluorescence spectroscopy. Organo-hectorite nanoparticles were synthesized at 90 °C in the presence of Cm(III). Within 120 h, hectorite particles were formed. Time-resolved laser fluorescence spectroscopy was used to identify Cm(III) species during various synthesis steps and to characterize the structural incorporation mechanism. The formation of a Cm-containing Mg hydroxide precursor and the reaction with aqueous silica in a pH range of 9-10 to form TOT layers were identified to be key steps for trivalent actinide incorporation in hectorite via coprecipitation.  相似文献