River discharge reduces reef coral diversity in Palau     

Golbuu Y  van Woesik R  Richmond RH  Harrison P  Fabricius KE 《Marine pollution bulletin》2011,62(4):824-831

Coral community structure is often governed by a suite of processes that are becoming increasingly influenced by land-use changes and related terrestrial discharges. We studied sites along a watershed gradient to examine both the physical environment and the associated biological communities. Transplanted corals showed no differences in growth rates and mortality along the watershed gradient. However, coral cover, coral richness, and coral colony density increased with increasing distance from the mouth of the bay. There was a negative relationship between coral cover and mean suspended solids concentration. Negative relationships were also found between terrigenous sedimentation rates and the richness of adult and juvenile corals. These results have major implications not only for Pacific islands but for all countries with reef systems downstream of rivers. Land development very often leads to increases in river runoff and suspended solids concentrations that reduce coral cover and coral diversity on adjacent reefs.  相似文献   

Exploring the Boundaries of Web Map Services: The Example of the Online Injury Atlas for Ontario     

Claus Rinner  Byron Moldofsky  Michael D. Cusimano  Sean Marshall  Tony Hernandez 《Transactions in GIS》2011,15(2):129-145

Injury from causes such as falls, traffic accidents, or violence is a major public health issue globally. Injury prevention research aims to identify vulnerable populations and places by analyzing the spatial patterns of demographic and socio‐economic risk factors associated with elevated injury rates. The stakeholders in injury prevention and control are often distributed across government and public health institutions, non‐profits, and even the private sector (e.g. insurance firms). While this situation calls for distributed, online research tools, their implementation may conflict with health data confidentiality and license limitations for socio‐economic data. In this article, we present the Online Injury Atlas for Ontario, which was designed with the explicit goal of making use of, and contributing to, the Canadian Geospatial Data Infrastructure. We propose a service‐based architecture that integrates publicly accessible map services with protected data layers. Thereby, we demonstrate the benefits of using spatial data infrastructures alongside private data at different levels of protection. In addition, we discuss the extensive data processing needs and specific cartographic design requirements of a Web atlas in the health and social sciences domain.  相似文献   

Large and small numbers: options for quantifying the costs of extremes on transport now and in 40 years     

Claus Doll  Stefan Klug  Riccardo Enei 《Natural Hazards》2014,72(1):211-239

The past 15 years has been characterized by a high density of record-breaking weather extremes in Europe. These include the extratropical cyclones Lothar, Kyrill and Xynthia across western and mid Europe; the major floods in the UK, Germany and eastern Europe; the heat waves in 2003 and 2007 and, after a long period of mild winters, the heavy winter seasons in 2009/2010 and 2010/2011. Inspired by the rising trends in weather-related damages worldwide and the studies on the topic carried out in overseas, the EC funded the sister projects such as Weather Extremes-Assessing the Impacts on Transport and Hazards for European Regions (WEATHER), EWENT and ECCONET to determine the magnitude of current and future risks to the European transport sector and to assess suitable adaptation strategies. This paper presents the assessment framework of the WEATHER project and the results of weather-inflicted damage costs now and in 2040–2050. Total annual damages are found to be around €2.5 billion, which largely attribute to road traffic. However, broken down to passenger and ton kilometers the highest risk is borne by rail traffic due to its expensive infrastructures and its comparably complex operating structure. This indication even amplifies when looking four decades ahead: while average road transport costs will only raise by 7 % due to milder winters, rail traffic costs may increase by up to 80 % due to more floods and less predictable winter periods. A comparison with the results of the EWENT study uncovers a high range of uncertainty concerning methodological approaches and data treatment. Thus, the final figures might even be much higher.  相似文献   

Dielectric properties of iron-bearing trioctahedral phyllosilicates     

Claus H. Rüscher  Stefan Gall 《Physics and Chemistry of Minerals》1997,24(5):365-373

Measurements of the real part of conductivity (σ′) and dielectric function (?′) were performed on large crystal flakes of biotite (Moen) and vermiculite (Benahavis), at variable frequencies (0.1 to 1000 kHz) and as a function of temperature (300 K<T<900 K). By heating, cooling and repeated heating experiments under inert atmospheric conditions effects involving water (H₂O) diffusion and electrical transport were separated. The effect of dehydration dominates the functional dependence of ?′ on T at frequencies below about 100 kHz, within the first heating run. Six dehydration steps for vermiculite Benahavis and two broad features for biotite Moen are observed, the water being transported effectively only in the interlayers. Electrical transport occurs along Fe paths within the octahedral layers and can be described by σ′=σ_dc+A·w^s. Values of s are between 0.45 and 0.8. σ_dc shows a temperature dependence according to exp(?E_a(T)/kT) with E_a(T) between 0.3 and 0.6 eV. E_a is suggested to be composed of a polaron plus disorder contribution.  相似文献   

Total Solar Irradiance Variation During Rapid Sunspot Growth     

H. Jabran Zahid  Hugh S. Hudson  Claus FrÖhlich 《Solar physics》2004,222(1):1-15

Large sunspot areas correspond to dips in the total solar irradiance (TSI), a phenomenon associated with the local suppression of convective energy transport in the spot region. This results in a strong correlation between sunspot area and TSI. During the growth phase of a sunspot other physics may affect this correlation; if the physical growth of the sunspot resulted in surface flows affecting the temperature, for example, we might expect to see an anomalous variation in TSI. In this paper we study NOAA active region 8179, in which large sunspots suddenly appeared near disk center, at a time (March 1998) when few competing sunspots or plage regions were present on the visible hemisphere. We find that the area/TSI correlation does not significantly differ from the expected pattern of correlation, a result consistent with a large thermal conductivity in solar convection zone. In addition we have searched for a smaller-scale effect by analyzing white-light images from MDI (the Michelson Doppler Imager) on SOHO. A representative upper-limit energy consistent with the images is on the order of 3×10³¹ ergs, assuming the time scale of the actual spot area growth. This is of the same order of magnitude as the buoyant energy of the spot emergence even if it is shallow. We suggest that detailed image analyses of sunspot growth may therefore show `transient bright rings' at a detectable level.  相似文献   

IN-FLIGHT PERFORMANCE OF THE VIRGO LUMINOSITY OSCILLATIONS IMAGER ABOARD SOHO     

Appourchaux  Thierry  Andersen  Bo N.  Fröhlich  Claus  Jiménez  Antonio  Telljohann  Udo  Wehrli  Christoph 《Solar physics》1997,170(1):27-41

The Luminosity Oscillations Imager (LOI) is a part of the VIRGO instrument aboard the Solar and Heliospheric Observatory (SOHO). The scientific objective of the LOI experiment is to identify and characterize pressure and internal gravity oscillations of the Sun by observing the radiance variations. The LOI is a low-resolution imager with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 nm. The low resolution capability of the instrument allows the identification of individual azimuthal orders for l = 0 to 7, without suffering the mixing that affects integrated solar disk instruments. The performance, calibrations and instrumental effects of the LOI are described together with the procedures for extracting the solar p modes.  相似文献   

The design and performance of the Gaia photometric system     

C. Jordi  E. Høg  A. G. A. Brown  L. Lindegren  C. A. L. Bailer-Jones  J. M. Carrasco  J. Knude  V. Strai&#;ys  J. H. J. de Bruijne  J.-F. Claeskens  R. Drimmel  F. Figueras  M. Grenon  I. Kolka  M. A. C. Perryman  G. Tautvai&#;ien&#;  V. Vansevi&#;ius  P. G. Willemsen  A. Brid&#;ius  D. W. Evans  C. Fabricius  M. Fiorucci  U. Heiter  T. A. Kaempf  A. Kazlauskas  A. Ku&#;inskas  V. Malyuto  U. Munari  C. Reylé  J. Torra  A. Vallenari  K. Zdanavi&#;ius  R. Korakitis  O. Malkov  A. Smette 《Monthly notices of the Royal Astronomical Society》2006,367(1):290-314

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In-Flight Performance of the Virgo Solar Irradiance Instruments on Soho   总被引：3，自引：0，他引：3  

Claus Fröhlich  Dominique A. Crommelynck  Christoph Wehrli  Martin Anklin  Steven Dewitte  Alain Fichot  Wolfgang Finsterle  Antonio Jiménez  André Chevalier  Hansjörg Roth 《Solar physics》1997,175(2):267-286

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Astrodynamical Space Test of Relativity using Optical Devices I (ASTROD I)—a class-M fundamental physics mission proposal for cosmic vision 2015–2025: 2010 Update     

Claus Braxmaier  Hansj?rg Dittus  Bernard Foulon  Ertan G?klü  Catia Grimani  Jian Guo  Sven Herrmann  Claus L?mmerzahl  Wei-Tou Ni  Achim Peters  Benny Rievers  étienne Samain  Hanns Selig  Diana Shaul  Drazen Svehla  Pierre Touboul  Gang Wang  An-Ming Wu  Alexander F. Zakharov 《Experimental Astronomy》2012,34(2):181-201

ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test General Relativity with an improvement in sensitivity of over 3 orders of magnitude, improving our understanding of gravity and aiding the development of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is envisaged as the first in a series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way, two-wavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth, to achieve the ASTROD I goals.For this mission, accurate pulse timing with an ultra-stable clock, and a drag-free spacecraft with reliable inertial sensor are required. T2L2 has demonstrated the required accurate pulse timing; rubidium clock on board Galileo has mostly demonstrated the required clock stability; the accelerometer on board GOCE has paved the way for achieving the reliable inertial sensor; the demonstration of LISA Pathfinder will provide an excellent platform for the implementation of the ASTROD I drag-free spacecraft. These European activities comprise the pillars for building up the mission and make the technologies needed ready. A second mission, ASTROD or ASTROD-GW (depending on the results of ASTROD I), is envisaged as a three-spacecraft mission which, in the case of ASTROD, would test General Relativity to one part per billion, enable detection of solar g-modes, measure the solar Lense-Thirring effect to 10 parts per million, and probe gravitational waves at frequencies below the LISA bandwidth, or in the case of ASTROD-GW, would be dedicated to probe gravitational waves at frequencies below the LISA bandwidth to 100?nHz and to detect solar g-mode oscillations. In the third phase (Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD bandwidth. This paper on ASTROD I is based on our 2010 proposal submitted for the ESA call for class-M mission proposals, and is a sequel and an update to our previous paper (Appouchaux et al., Exp Astron 23:491?C527, 2009; designated as Paper I) which was based on our last proposal submitted for the 2007 ESA call. In this paper, we present our orbit selection with one Venus swing-by together with orbit simulation. In Paper I, our orbit choice is with two Venus swing-bys. The present choice takes shorter time (about 250?days) to reach the opposite side of the Sun. We also present a preliminary design of the optical bench, and elaborate on the solar physics goals with the radiation monitor payload. We discuss telescope size, trade-offs of drag-free sensitivities, thermal issues and present an outlook.  相似文献   

Sources of oxygen flux in groundwater during induced bank filtration at a site in Berlin, Germany     

Claus Kohfahl  Gudrun Massmann  Asaf Pekdeger 《Hydrogeology Journal》2009,17(3):571-578

The microbial degradation of pharmaceuticals found in surface water used for artificial recharge is strongly dependent on redox conditions of the subsurface. Furthermore the durability of production wells may decrease considerably with the presence of oxygen and ferrous iron due to the precipitation of trivalent iron oxides and subsequent clogging. Field measurements are presented for oxygen at a bank filtration site in Berlin, Germany, along with simplified calculations of different oxygen pathways into the groundwater. For a two-dimensional vertical cross-section, oxygen input has been calculated for six scenarios related to different water management strategies. Calculations were carried out in order to assess the amount of oxygen input due to (1) the infiltration of oxic lake water, (2) air entrapment as a result of water table oscillations, (3) diffusive oxygen flux from soil air and (4) infiltrating rainwater. The results show that air entrapment and infiltrating lake water during winter constitute by far the most important mechanism of oxygen input. Oxygen input by percolating rainwater and by diffusive delivery of oxygen in the gas phase is negligible. The results exemplify the importance of well management as a determining factor for water oscillations and redox conditions during artificial recharge.  相似文献