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11.
The thermal springs Trollosen and Fisosen, located on the High Arctic archipelago Svalbard, discharge saline groundwaters rich in hydrogen sulfide and ammonium through a thick layer of permafrost. Large amounts of biomass that consist of filamentous microorganisms containing sulfur granules, as analyzed with energy dispersive X-ray analysis, were found in the outflow. Prokaryotic 16S rRNA gene libraries and quantitative polymerase chain reaction (qPCR) analyses reported bacteria of the γ- and ?-proteobacterial classes as the dominant organisms in the filaments and the planktonic fractions, closely related to known chemolithoautotrophic sulfur oxidizers (Thiotrix and Sulfurovum). Archaea comprised ~1% of the microbial community, with the majority of sequences affiliated with the Thaumarchaeota. Archaeal and bacterial genes coding for a subunit of the enzyme ammonia monooxygenase (amoA) were detected, as well as 16S?rRNA genes of Nitrospira, all of which is indicative of potential complete nitrification in both springs. 16S rRNA sequences related to methanogens and methanotrophs were detected as well. This study provides evidence that the microbial communities in Trollosen and Fisosen are sustained by chemolithotrophy, mainly through the oxidation of reduced sulfur compounds, and that ammonium and methane might be minor, additional sources of energy and carbon. 相似文献
12.
Spatial Reference Systems 总被引:1,自引:0,他引:1
Spatial Cognition and Computation - 相似文献
13.
Recently the galactic plane has been observed in the low and medium energy gamma-ray range in the directions towards the center and anticenter. Spectral measurements are now available at those energies, where the contribution from π°-decay gamma rays can be neglected. The high MeV-fluxes observed in both parts of the Galaxy are an indication of either a strong electron induced component or a high contribution from unresolved sources. Several interstellar cosmic-ray electron spectra have been used to calculate the contribution from electron bremsstrahlung and inverse Compton collisions with optical, infrared and 2.7 K black-body photons. From these calculations restrictions on the interstellar electron spectrum are derived. 相似文献
14.
Spectra of the northern polar coronal hole measured with the SUMER spectrometer on SOHO on 25 October 1996 are analyzed. We
present spectra taken at locations on the solar disk where part of the spectrometer slit intersects a polar coronal hole region
and an area of brighter emission from outside of the coronal hole area. By comparing the line intensities between the parts
of the spectrum taken inside the "dark" area of the coronal holes and the brighter regions, we work out the signatures of
the specific coronal hole in the chromosphere, transition region and lower corona. We find that emissions of neutral atom
lines, of which there are many in the spectrum of SUMER, show no difference between the coronal hole and the bright boundary
areas, whereas all ionized species show strong intensity enhancements, including the continuum emissions of carbon and hydrogen.
These enhancements are larger than in normal quiet Sun areas.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
Peslier Anne H. Schönbächler Maria Busemann Henner Karato Shun-Ichiro 《Space Science Reviews》2017,212(1-2):811-811
Space Science Reviews - Correction to: Space Sci Rev DOI This article has been corrected. Figure 3 was initially published with erroneous axis titles in Fig. 3B and 3D where the $x$ axis should be... 相似文献
16.
V. Schönfelder 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(4):59-69
During the last few years quite some progress has been achieved in the field of low and medium energy gamma-ray astronomy below about 30 MeV. Gamma rays from the galactic center and anti-center region have been detected, which require a high interstellar electron flux in the 100 MeV range, if they are predominantly diffuse in nature. Though the Crab pulsar and its nebula are still the only galactic gamma-ray sources which definitely have been detected, some recently determined upper limits to the gamma-ray fluxes of other radio pulsars are close to the theoretically expected values. Active galaxies seem to have a maximum of luminosity in the range between several 100 keV and a few MeV and, therefore, are of special interest. First observational results have been reported on the Seyfert galaxies NGC 4151 and MCG 8-11-11, and the radio galaxy CenA. The nature of the diffuse cosmic gamma-ray component at low gamma-ray energies is not yet solved. Unresolved active galaxies are good candidates for its origin.Considering the present status of gamma ray astronomy the study of galactic sources like radio pulsars and the unidentified high energy gamma-ray sources, the Milky Way as a whole, active galaxies and the diffuse cosmic sky seem to be the prime targets for broad band observations below 30 MeV in the GRO area. An unexplored field like that of low energy gamma-ray astronomy, however, is always open for surprises. 相似文献
17.
Elisabeth Abbe Thomas Renger Maciej Sznajder Benjamin Klemmed Elisa Sachse René Hübner Tilman Schüler Yves Bärtling Benjamin Muchow Martin Tajmar Tino Schmiel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(7):2312-2321
Over the last years, Carbon Nanotubes (CNT) drew interdisciplinary attention. Regarding space technologies a variety of potential applications were proposed and investigated. However, no complex data on the behaviour and degradation process of carbon nanotubes under space environment exist. Therefore, it is necessary to investigate the performance of these new materials in space environment and to revaluate the application potential of CNTs in space technologies.Hence, CiREX (Carbon Nanotubes – Resistance Experiment) was developed as a part of a student project. It is a small and compact experiment, which is designed for CubeSat class space satellites. These are a class of nanosatellites with a standardized size and shape. The CiREX design, electrical measurements and the satellites interfaces will be discussed in detail. CiREX is the first in-situ space material experiment for CNTs.To evaluate the data obtained from CiREX, ground validation tests are mandatory. As part of an extensive test series the behaviour of CNTs under solar ultra violet light (UV) and vacuum ultraviolet light (VUV) was examined. Single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and MWNT/resin composite (ME) were exposed to different light sources. After the exposure, the defect density was investigated with Raman spectroscopy. There is a clear indication that UV and VUV light can increase the defect density of untreated CNTs and influence the electrical behaviour. 相似文献
18.
Markus Vennebusch Steffen Schön Ulrich Weinbach 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In this paper, a turbulence theory-based simulation procedure for slant tropospheric delay variations is presented. Based on this procedure tropospheric delay variations are simulated for three different geometric scenarios. The stochastic behaviour of the generated time series is assessed in terms of temporal structure functions. It is shown that the temporal structure functions – in general – follow a 5/3 to 2/3 power-law behaviour. Deviations from this behaviour due to the complex interaction between varying observation geometry and atmospheric/turbulent conditions are discussed. 相似文献
19.
U Micke M Sch?fer A Anton G Horneck H Bücker 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(2-3):59-63
DNA damage induced by heavy ions in bacterial cells and bacteriophages such as Bacillus subtilis, E. coli and Bacteriophage T1 were investigated by analyzing the double strand breaks in the chromosomal DNA. This kind of lesion is considered as one of the main reasons for lethal events. To analyze double strand breaks in long molecules of DNA--up to some Mbp in length--the technique of pulse field agarose gel electrophoresis has been used. This allows the detection of one double strand break per genome. Cell lysis and DNA isolation were performed in small agarose blocks directly. This procedure secured minimum DNA destruction by shearing forces. After running a gel, the DNA was stained with ethidium bromide. The light intensity of ethidium bromide fluorescence for both the outcoming (running) DNA and the remaining intact DNA were measured by scanning. The mean number of double strand breaks was calculated by determining the quotient of these intensities. Strand break induction after heavy ion and X-ray irradiation was compared. 相似文献
20.
Peslier Anne H. Schönbächler Maria Busemann Henner Karato Shun-Ichiro 《Space Science Reviews》2017,212(1-2):743-810
Space Science Reviews - The concentration and distribution of water in the Earth has influenced its evolution throughout its history. Even at the trace levels contained in the planet’s deep... 相似文献