Nitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments     

Lepoint G  Vangeluwe D  Eisinger M  Paster M  van Treeck P  Bouquegneau JM  Gobert S 《Marine pollution bulletin》2004,48(5-6):465-470

A (15)N tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement, because leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural re-colonisation processes. The increase of the (15)N content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots).  相似文献   

The Triassic of Monte San Giorgio in the World Heritage List of UNESCO: An opportunity for science, the local people and tourism     

Markus Felber  Heinz Furrer  Andrea Tintori 《Eclogae Geologicae Helvetiae》2004,97(1):1-2

No abstract.  .  相似文献   

FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – II. Imagery and Data Management     

Lemaire  P.  Wilhelm  K.  Curdt  W.  SchÜle  U.  Marsch  E.  Poland  A. I.  Jordan  S. D.  Thomas  R. J.  Hassler  D. M.  Vial  J. C.  KÜhne  M.  Huber  M. C. E.  Siegmund  O. H. W.  Gabriel  A.  Timothy  J. G.  Grewing  M. 《Solar physics》1997,170(1):105-122

SUMER – Solar Ultraviolet Measurements of Emitted Radiation – is not only an extreme ultraviolet (EUV) spectrometer capable of obtaining detailed spectra in the range from 500 to 1610 Å, but, using the telescope mechanisms, it also provides monochromatic images over the full solar disk and beyond, into the corona, with high spatial resolution. We report on some aspects of the observation programmes that have already led us to a new view of many aspects of the Sun, including quiet Sun, chromospheric and transition region network, coronal hole, polar plume, prominence and active region studies. After an introduction, where we compare the SUMER imaging capabilities to previous experiments in our wavelength range, we describe the results of tests performed in order to characterize and optimize the telescope under operational conditions. We find the spatial resolution to be 1.2 arc sec across the slit and 2 arc sec (2 detector pixels) along the slit. Resolution and sensitivity are adequate to provide details on the structure, physical properties, and evolution of several solar features which we then present. Finally some information is given on the data availability and the data management system.  相似文献   

Observations of sunspot transition region oscillations   总被引：1，自引：0，他引：1  

Brynildsen  N.  Maltby  P.  Leifsen  T.  Kjeldseth-Moe  O.  Wilhelm  K. 《Solar physics》2000,191(1):129-159

Oscillations with a period of 3 minutes are observed in the transition region of six sunspots with the Solar and Heliospheric Observatory - SOHO joint observing programme for velocity fields in sunspot regions. Observations of the transition region lines Ov 629 and Nv 1238, 1242 with the SUMER instrument show significant differences in the amplitude of the 3-minute oscillations from one sunspot to another, both in intensity and line-of-sight velocity. In four sunspots the central part of the umbra is observed. Two of these sunspots show coincidence between the maxima in peak line intensity and velocity directed towards the observer, as is expected for an upward-propagating acoustic wave. The two other sunspots show large oscillation amplitudes and a difference of 25° between maxima in intensity and blue shift. The possible effect of partial wave reflection on the observed phase relation is discussed. For one sunspot only a part of the umbra, close to the penumbra, was observed and the observations show a difference of 50° between maxima in intensity and blueshift. For the smallest sunspot the observations are found to be contaminated by contributions from an area without oscillations. Observed oscillations in line width are small, but probably significant in two sunspots. The observations of NOAA 8378 allow us to compare simultaneous recordings of the oscillations in the chromospheric Siii 1260 line with the oscillations in the transition region lines. We question the suggestion by Fludra (1999) that the sunspot transition region oscillations are a typical feature of the sunspot plumes.  相似文献   

SUMER - Solar Ultraviolet Measurements of Emitted Radiation     

K. Wilhelm  W. Curdt  E. Marsch  U. Schühle  P. Lemaire  A. Gabriel  J. -C. Vial  M. Grewing  M. C. E. Huber  S. D. Jordan  A. I. Poland  R. J. Thomas  M. Kühne  J. G. Timothy  D. M. Hassler  O. H. W. Siegmund 《Solar physics》1995,162(1-2):189-231

The instrument SUMER - Solar Ultraviolet Measurements of Emitted Radiation is designed to investigate structures and associated dynamical processes occurring in the solar atmosphere, from the chromosphere through the transition region to the inner corona, over a temperature range from 10⁴ to 2 × 10⁶ K and above. These observations will permit detailed spectroscopic diagnostics of plasma densities and temperatures in many solar features, and will support penetrating studies of underlying physical processes, including plasma flows, turbulence and wave motions, diffusion transport processes, events associated with solar magnetic activity, atmospheric heating, and solar wind acceleration in the inner corona. Specifically, SUMER will measure profiles and intensities of EUV lines; determine Doppler shifts and line broadenings with high accuracy; provide stigmatic images of the Sun in the EUV with high spatial, spectral, and temporal resolution; and obtain monochromatic maps of the full Sun and the inner corona or selected areas thereof. SUMER will be flown on the Solar and Heliospheric Observatory (SOHO), scheduled for launch in November, 1995. This paper has been written to familiarize solar physicists with SUMER and to demonstrate some command procedures for achieving certain scientific observations.  相似文献   

Absolute phase center corrections of satellite and receiver antennas   总被引：9，自引：2，他引：9  

Ralf Schmid  Markus Rothacher  Daniela Thaller  Peter Steigenberger 《GPS Solutions》2005,9(4):283-293

Results of the estimation of azimuth-dependent phase center variations (PCVs) of GPS satellite antennas using global GPS data are presented. Significant variations of up to ±3–4 mm that are demonstrated show excellent repeatability over eight years. The application of the azimuthal PCVs besides the nadir-dependent ones will lead to a further reduction in systematic antenna effects. In addition, the paper focuses on the benefit of a possible transition from relative to absolute PCVs. Apart from systematic changes in the global station coordinates, one can expect the GPS results to be less dependent on the elevation cut-off angle. This, together with the significant reduction of tropospheric zenith delay biases between GPS and VLBI, stands for an important step toward more consistency between different space geodetic techniques.  相似文献   

Analysis of heavy rainfall events in North Rhine–Westphalia with radar and raingauge data     

Markus Jessen  Thomas Einfalt  Andr Stoffer  Bernd Mehlig 《Atmospheric Research》2005,77(1-4):337

Five heavy rainfall events were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be difficult in the vicinity of heavy local rain cells. Four adjustment methods were analysed and radar data from different radar stations were compared. As a further result of this project, the spatial extent of the precipitation fields was identified by adjusted radar data and compared to raingauge data. For each rainfall event, radar derived accumulated rainfall images and catchment time series were produced.  相似文献   

A calibrated composite section for the Late Jurassic Reuchenette Formation in northwestern Switzerland (?Oxfordian, Kimmeridgian sensu gallico, Ajoie-Region)     

Markus Jank  Andreas Wetzel  Christian A. Meyer 《Eclogae Geologicae Helvetiae》2006,99(2):175-191

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Possibilities and Limitations of Interdisciplinary, User-oriented Research: Experiences from the German Research Network Natural Disasters     

Bruno Merz  Jana Friedrich  Markus Disse  Jochen Schwarz  Johann G. Goldammer  Jochen Wächter 《Natural Hazards》2006,38(1-2):3-20

The German Research Network for Natural Disasters (DFNK) linked 15 partners with scientific expertise in the field of natural hazards. Main objectives were the development and provision of the scientific fundamentals for an advanced risk management of important natural disasters in Germany, i.e., floods, earthquakes, storms and wildland fires. This included risk analyses, the development of information systems for supporting disaster management, and recommendations for risk reduction measures. This paper gives an overview of DFNK and summarises its experiences concerning multidisciplinarity and user-orientation. It illustrates the concept of risk chains, causally linking the different processes from hazard to risk. The step from hazard to risk requires interdisciplinary research teams. The experiences show that integrative concepts allow results not achievable with mono-disciplinary approaches. Integrative approaches pave the way to harmonised safety considerations taking into account the different hazards in a region within a common framework. User-orientation, policy advice and development of operational tools are key issues of disaster research. The experiences of DFNK illustrate the limitations of a research network in bridging the gap between research and application within rather short-term projects. Successful cooperation with users could be established by those activities where, at the beginning of the project, a user was identified who had a strong interest in solving an urgent problem.  相似文献   

Assessment of Discharge through a Dike Breach and Simulation of Flood Wave Propagation   总被引：2，自引：0，他引：2  

Paul Kamrath  Markus Disse  Matthias Hammer  Jürgen Köngeter 《Natural Hazards》2006,38(1-2):63-78

This paper presents a simple and fast method to calculate flow through a dike breach. The approach was based on two-dimensional numerical simulations of idealized dike breakages at straight river-sections. As a result, computation of discharge through a breach can be achieved by use of the new developed formula (denoted as dike break formula). Furthermore, a methodology that combines one-dimensional hydrodynamic modelling, the dike break formula and a simple GIS-based method to estimate inundation areas is described. This fast and easy-to-handle tool can be utilized for near real-time forecasting or evacuation decisions. Detailed predictions were made for a number of flood and dike break scenarios at the River Rhine to prove the accuracy of the new method compared with two-dimensional numerical models.  相似文献