On the detection of newly created CN radicals in comets     

Bertram Donn  Regina J. Cody 《Icarus》1978,34(2):436-440

Laboratory investigations of CN radical formation by photodissociation of parent molecules have suggested the possibility of observing emission lines in cometary spectra from newly formed CN radicals. These laboratory studies have shown that high initial internal excitation of CN is the rule with excitation of rotational levels N up to 70. In the collisionless environment of the cometary atmosphere this initial excitation would yield a corresponding distribution for the lowest vibrational level of the ground X²Σ⁺ state. Our calculations show that it is feasible with present observational techniques to detect photochemically excited lines with N ～ 30 in the 0-0 band of the violet system.  相似文献   

Pyrolytic and spectroscopic studies of Eocene resin from Vastan lignite Mine,Cambay basin,Western India     

Monalisa Mallick  Suryendu Dutta  Paul F. Greenwood  Norbert Bertram 《Journal of the Geological Society of India》2009,74(1):16-22

The molecular structure of an Eocene fossil resin (Vastan, Cambay basin, Western India) has been investigated with complimentary spectroscopic techniques. The FTIR spectrum shows strong aliphatic CH _x (3000–2800 and 1460–1450 cm⁻¹) and CH₃ (1377 cm⁻¹) absorptions and less intense aromatic C=C (1560–1610 cm⁻¹) absorptions. The major products from analytical pyrolysis are cadalene based bicyclic sesquiterpenoids including some bicadinenes and bicadinanes. The polycadinane products confirm the fossil material as an Angiosperm dammar resin, associated with inputs of tropical rain forests supported by past climates.  相似文献   

Turbidity as a proxy for total suspended solids (TSS) and particle facilitated pollutant transport in catchments     

Hermann Rügner  Marc Schwientek  Barbara Beckingham  Bertram Kuch  Peter Grathwohl 《Environmental Earth Sciences》2013,69(2):373-380

Transport of hydrophobic organic pollutants in rivers is mainly coupled to transport of suspended particles. Turbidity measurements are often used to assess the amount of suspended solids in water. In this study, a monitoring campaign is presented where the total concentration of polycyclic aromatic hydrocarbons (PAHs), the amount of total suspended solids (TSS), and turbidity was measured in water samples from five neighboring catchments in southwest Germany. Linear correlations of turbidity and TSS were obtained which were in close agreement to the literature data. From linear regressions of turbidity versus total PAH concentrations in water, mean concentrations of PAH on suspended particles could be calculated and these varied by catchment. These values furthermore comprise a robust measure of the average sediment quality in a given catchment. Since in the catchments investigated in this study, PAH concentrations on suspended particles were stable over a large turbidity range (1–114 Nephelometric Turbidity Units), turbidity could be used as a proxy for total PAHs and likely other highly hydrophobic organic pollutants in river water if the associated correlations are established. Based on that, online monitoring of turbidity (e.g., by optical backscattering sensors) seems very promising to determine annual pollutant fluxes.  相似文献   

Catchments as reactors: a comprehensive approach for water fluxes and solute turnover   总被引：1，自引：1，他引：0  

Peter Grathwohl  Hermann Rügner  Thomas Wöhling  Karsten Osenbrück  Marc Schwientek  Sebastian Gayler  Ute Wollschläger  Benny Selle  Marion Pause  Jens-Olaf Delfs  Matthias Grzeschik  Ulrich Weller  Martin Ivanov  Olaf A. Cirpka  Ulrich Maier  Bertram Kuch  Wolfgang Nowak  Volker Wulfmeyer  Kirsten Warrach-Sagi  Thilo Streck  Sabine Attinger  Lars Bilke  Peter Dietrich  Jan H. Fleckenstein  Thomas Kalbacher  Olaf Kolditz  Karsten Rink  Luis Samaniego  Hans-Jörg Vogel  Ulrike Werban  Georg Teutsch 《Environmental Earth Sciences》2013,69(2):317-333

Sustainable water quality management requires a profound understanding of water fluxes (precipitation, run-off, recharge, etc.) and solute turnover such as retention, reaction, transformation, etc. at the catchment or landscape scale. The Water and Earth System Science competence cluster (WESS, http://www.wess.info/) aims at a holistic analysis of the water cycle coupled to reactive solute transport, including soil–plant–atmosphere and groundwater–surface water interactions. To facilitate exploring the impact of land-use and climate changes on water cycling and water quality, special emphasis is placed on feedbacks between the atmosphere, the land surface, and the subsurface. A major challenge lies in bridging the scales in monitoring and modeling of surface/subsurface versus atmospheric processes. The field work follows the approach of contrasting catchments, i.e. neighboring watersheds with different land use or similar watersheds with different climate. This paper introduces the featured catchments and explains methodologies of WESS by selected examples.  相似文献   

Steady-state convection in a rotating long cavity     

Bertram Boehrer 《地球物理与天体物理流体动力学》2013,107(1-2):105-126

Abstract

Convection experiments in a rotating long cavity were conducted to investigate the changes introduced by Coriolis-force to the well understood convection in the (nonrotating) long cavity. In the far convective regime, the results indicated that large-scale features of the convection were dominated by geostrophically balanced confined primary currents. Close to the transition regime, where the intruding currents gain a thickness close to the vertical dimension of the tank, secondary features became predominant. In the transition regime, these secondary features were not present and the simple picture of two cavity filling counter currents with laterally tilted isotherms could be confirmed.  相似文献   

Analytical solutions for Ulrich's spherical thermal     

Lee A. Bertram   《Dynamics of Atmospheres and Oceans》1976,1(1):51-70

Ulrich's radiating, compressible, spherical thermal model of turbulent convection in a superadiabatic atmosphere is examined analytically. Since the governing ordinary differential equations form an autonomous system, for which the characteristics are obtained by asymptotic approximations, the possible solutions can be exhaustively classified on the basis of their evolution in time. Results show that there are two types of thermal with finite lifetimes, and that these occur, in an atmosphere of fixed background turbulence and structure, only when the initial size and velocity of the thermal are restricted to specified regions of the (size, velocity) plane. Comparison of the analytical solution for the characteristics to a stable numerical solution indicates excellent agreement. This analytical solution should allow detailed structure calculations for superadiabatic layers at a computational cost comparable to present mixing-length calculations.  相似文献   

Computer modelling of Al/Si ordering in sillimanite     

U. C. Bertram  Volker Heine  I. L. Jones  Geoffrey D. Price 《Physics and Chemistry of Minerals》1990,17(4):326-333

Computer simulation is used to investigate the effect of Al/Si disordering over the tetrahedral sites on the lattice energy and the lattice constants of the mineral sillimanite Al₂SiO₅. A methodology for an atomistic assessment of the energy of the reaction 2(Si-O-Al)→(Si-O-Si)+(Al-O-Al) and its various contributions is established. This ordering energy is 0.97 eV for nearest neighbour sites in the ab-plane and 0.56 eV for those separated in the c-direction. The large difference is due to a greater constraint on the atomic relaxation in the ab-plane and shows the structural dependence of the ordering energy. Its magnitude appears to be determined by a complicated balance between Coulomb and short-range repulsive energy involving strain over many bonds, both in the ordered and disordered structures. There is also a significant interaction between second neighbour sites whereas the contribution of more distant neighbours is negligible. The lattice energies of most of the 154 configurations studied show a linear behaviour as a function of short-range order, specified by the number of Al-Al pairs. The ordering temperature T_c, estimated on the basis of a statistical mechanical model of disordering, and the calculated ordering energies are in semi-quantitative agreement with experimental values.  相似文献   

Reconceptualizing the role of the user of spatial data infrastructure   总被引：3，自引：0，他引：3  

Nama Raj Budhathoki  Bertram Bruce  Zorica Nedovic-Budic 《GeoJournal》2008,72(3-4):149-160

Spatial data infrastructures, which are Internet-based mechanisms for the coordinated production, discovery, and use of geospatial information in the digital environment, have diffused worldwide in the last two decades. Currently, there are about one hundred spatial data infrastructures at the national level and many other at supra- and sub-national levels. These contemporary spatial data infrastructures operate with two main assumptions: formal organizations are the producers and suppliers of geospatial information; users are the passive recipients of information. The recent phenomenon of volunteered geographic information departs from these assumptions. In this paper, we argue that reconceptualizing the user of a spatial data infrastructure can accommodate this new phenomenon. Such a reconceptualization creates a middle ground between spatial data infrastructure and volunteered geographic information, which has important implications for future research.  相似文献