Combination of different space-geodetic observations for regional ionosphere modeling   总被引：2，自引：1，他引：1  

Denise Dettmering  Michael Schmidt  Robert Heinkelmann  Manuela Seitz 《Journal of Geodesy》2011,85(12):989-998

Most of the space-geodetic observation techniques can be used for modeling the distribution of free electrons in the Earth’s ionosphere. By combining different techniques one can take advantage of their different spatial and temporal distributions as well as their different observation characteristics and sensitivities concerning ionospheric parameter estimation. The present publication introduces a procedure for multi-dimensional ionospheric modeling. The model consists of a given reference part and an unknown correction part expanded in terms of B-spline functions. This approach is used to compute regional models of Vertical Total Electron Content (VTEC) based on the International Reference Ionosphere (IRI 2007) and GPS observations from terrestrial Global Navigation Satellite System (GNSS) reference stations, radio occultation data from Low Earth Orbiters (LEOs), dual-frequency radar altimetry measurements, and data obtained by Very Long Baseline Interferometry (VLBI). The approach overcomes deficiencies in the climatological IRI model and reaches the same level of accuracy than GNSS-based VTEC maps from IGS. In areas without GNSS observations (e.g., over the oceans) radio occultations and altimetry provide valuable measurements and further improve the VTEC maps. Moreover, the approach supplies information on the offsets between different observation techniques as well as on their different sensitivity for ionosphere modeling. Altogether, the present procedure helps to derive improved ionospheric corrections (e.g., for one-frequency radar altimeters) and at the same time it improves our knowledge on the Earth’s ionosphere.  相似文献   

Can pharmaceuticals interfere with the synthesis of active androgens in male fish? An in vitro study   总被引：1，自引：0，他引：1  

Fernandes D  Schnell S  Porte C 《Marine pollution bulletin》2011,62(10):2250-2253

The in vitro interference of fibrate (gemfibrozil, clofibrate, clofibric acid), anti-inflammatory (ibuprofen, diclofenac), and anti-depressive (fluoxetine, fluvoxamine) drugs with key enzymatic activities—C17,20-lyase and CYP11β-involved in the synthesis of active androgens in gonads of male carp have been investigated. Among the tested compounds, fluvoxamine and fluoxetine were the strongest inhibitors of C17,20-lyase and CYP11β enzymes, with IC50s in the range of 321-335 μM and 244-550 μM, respectively. To our knowledge this is the first report on the interaction of pharmaceutical compounds with enzymatic systems involved in the synthesis of oxy-androgens. As oxy-androgens are known to influence spermatogenesis and stimulate reproductive behavior and secondary sexual characteristics in male fish, this work highlights the need for further investigating these endpoints when designing specific in vivo studies to assess the endocrine disruptive effect of pharmaceuticals in fish.  相似文献   

Structuring decision-making for ecosystem-based management     

Maria J. Espinosa-Romero  Kai M.A. Chan  Timothy McDaniels  Denise M. Dalmer 《Marine Policy》2011

Ecosystem-based management (EBM) has been widely accepted as the new paradigm to manage marine ecosystems. Although various efforts have been made to define key components, guidelines, and principles, in support of its implementation, there is still a gap between theory and practice. To implement EBM, managers require a decision-making framework in which the values of constituents, objectives and performance measures are consistent and used to evaluate and choose between alternatives. Structured decision-making (SDM) is a systematic approach that can contribute to develop this framework for EBM. SDM was used for the on-going EBM process on the west coast of Vancouver Island, British Columbia, Canada. This case study provides insights into how SDM can be implemented for EBM, as well as some challenges and opportunities encountered during the process.  相似文献   

VLBI Polarisation Properties of a Complete Sample of Radio-Loud BL Lacs     

Denise C. Gabuzda 《Astrophysics and Space Science》2003,288(1-2):39-50

The paper summarises the results to date of an ongoing multi-epoch, multi-frequency polarisation VLBI study of a complete sample of northern 1-Jy BL Lac objects. We discuss the physical origin of the characteristic polarisation properties of the core and jet structures as revealed by both general trends for the sample as a whole and more detailed observations of individual objects. It has been known for a decade that the distribution of the core polarisation position angles at moderate centimeter wavelengths is bimodal, with the corepolarisation angle being either aligned with or perpendicular to the direction of the inner VLBI jet. A preliminary analysis of the VLBI core spectral indices from 15–5 GHz suggests that this is the result of optical depth effects and that the two peaks in the distribution correspond to cores dominated by optically thin and thick regions of emission. This interpretation is supported by the results of quasi-simultaneous VLBI and optical polarisation observations, and also by VSOP polarisation observations of OJ287. Evidence for the presence of helical or toroidal magnetic fields associated with the VLBIjets is discussed. The collected results are discussed in the context of their possible implications for circular-polarisation studies of AGN. We are now beginning a search for parsec-scale circular polarisation in the complete sample BL Lac objects and hope to have our first results by June 2003.  相似文献   

Geochemical characterization and modeling of arsenic behavior in a highly contaminated mining soil     

Sara Bisone  Vincent Chatain  Denise Blanc  Mathieu Gautier  Rémy Bayard  Florence Sanchez  Rémy Gourdon 《Environmental Earth Sciences》2016,75(4):306

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Trace metal distribution in white shrimp (<Emphasis Type="Italic">Litopenaeus schmitti</Emphasis>) tissues from a Brazilian coastal area     

Juliana Ribeiro Nascimento  Edison Dausacker Bidone  Denise Rolão-Araripe  Karina Annes Keunecke  Elisamara Sabadini-Santos 《Environmental Earth Sciences》2016,75(11):990

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The integration of PESETA sectoral economic impacts into the GEM-E3 Europe model: methodology and results     

Juan-Carlos Ciscar  László Szabó  Denise van Regemorter  Antonio Soria 《Climatic change》2012,112(1):127-142

The PESETA project has estimated the physical effects of climate change in Europe for the following impact categories with a market valuation: agriculture, river floods, coastal systems and tourism. Four alternative scenarios of future climate change have been considered. The computable general equilibrium (CGE) GEM-E3 model for Europe has been used to integrate the PESETA damages under a consistent economic framework. The approach followed has been to assess the effects of future climate (as of 2080s) on today’s economy. This article details the way each sectoral impact has been integrated into the CGE model. The EU welfare loss is estimated to be in a range of 0.2% to 1%, depending on the climate future and the projected sea level rise. Results show that the Southern Europe region appears as the most vulnerable area to climate change. Impacts in coastal systems, agriculture and river floods determine the overall and regional pattern of impacts within Europe.  相似文献   

Long-term changes in a Mediterranean benthic community: Relationships between the polychaete assemblages and hydrological variations of the Rhône River     

Chantal Salen-Picard  Denise Arlhac 《Estuaries and Coasts》2002,25(6):1121-1130

Long-term changes in a macrobenthic, muddy community of the French Mediterranean coast, near the mouth of the Rhône River, were studied using 14 samples collected between 1963 and 1996 at 70-m depth. No drastic change in the community was observed over this time period. A factor correspondence analysis (FCA) performed with the most frequent polychaete species revealed that 3 sample groups were related to trends in the Rhône River discharge. Between 1965 and 1976, the effects of dumping events close to the study site acted in synergy with river drought leading to a drop in the abundance of the most common species of the community (e.g.,Sternaspis scutata). Floods were observed to be the main factor structuring the polychaete assemblages. These floods were subsequently followed, over a period of several years, by peaks of opportunistic species (Heteromastus filiformis, Prionospio cirrifera) and, with a time lag of 1 or 2 yr, by peaks ofS. scutata. Autumn and early winter floods were mainly the result of heavy rainfalls on the Mediterranean part of the drainage basin. They transported large amounts of mineral and particulate organic matter that increased the surface and subsurface deposit feeders assemblages. Late winter and spring floods originated from the north of the basin. They proportionally brought more dissolved material and were followed by developments of suspension and surface deposit feeders. Eutrophication of the area due to increased nitrate concentrations in the river is suggested to be responsible for the abundance, since the 1980s, of small-sized deposit feeders. There is a good parallel between the cumulative mean deviations of the river discharge and the quantity of soles caught in the area with a time lag of 4 yr between these two curves. These results may be of value to the management of the regional resources.  相似文献   

Hydrographic characterization of two tidal creeks with implications for watershed land use,flushing times,and benthic production     

Christopher Buzzelli  A. Frederick Holland  Denise M. Sanger  Paul C. Conrads 《Estuaries and Coasts》2007,30(2):321-330

Many coastal ecosystems are undergoing anthropogenic stress from large increases in population and urbanization. In many regions changes in freshwater and material inputs to the coastal zone are altering the biogeochemical and biological capacities of ecosystems. Despite increased watershed inputs, large tidal volumes and flushing indicative of macrotidal estuaries can modulate the fate of introduced materials masking some of the symptoms of eutrophication. The Land Use Coastal Ecosystem Study (LU-CES) examined linkages between land use and environmental properties of Malind and Okatee Creeks in South Carolina from 2001 to 2004. The objectives of this particular study were to assess the hydrography of the two macrotidal creek ecosystems, explore differences in dissolved oxygen (DO), and develop a better understanding of the variations in primary and benthic secondary production in southeastern creek ecosystems. Depth, pH, salinity, and DO were reduced and more variable in Malind Creek than in Okatee Creek, although both creeks had strong semidiurnal frequencies in salinity time signatures. While time series analyses of DO saturation in Malind Creek revealed a dominant semidiurnal pattern, Okatee Creek had a distinctly diel DO pattern. The strongly semidiurnal fluctuations in DO and reduced flushing time indicated that biological processes were not fast enough to influence DO in Malind Creek. The Okatee Creek system had a much greater storage volume, a wider marsh, and a dominant 25-h DO frequency. These attributes contributed to an estimated 8–10 times more phytoplankton-based carbon in Okatee Creek and twice the annual benthic production. As expected from their proximity to the upland, low surface area, and high organic content, both ecosystems were net heterotrophic. This fundamental understanding of tidal creek hydrography is being used to help define linkages among differential watershed land uses, flushing characteristics, and levels of biological production in coastal ecosystems of the southeastern United States.  相似文献   

Learning with Local Help: Expanding the Dialogue on Climate Change and Water Management in the Okanagan Region, British Columbia, Canada     

Stewart Cohen  Denise Neilsen  Scott Smith  Tina Neale  Bill Taylor  Mark Barton  Wendy Merritt  Younes Alila  Philippa Shepherd  Roger Mcneill  James Tansey  Jeff Carmichael  Stacy Langsdale 《Climatic change》2006,75(3):331-358

The research activity described in this report is a comprehensive regional assessment of the impacts of climate change on water resources and options for adaptation in the Okanagan Basin. The ultimate goal of the project is to develop integrated climate change and water resource scenarios to stimulate a multistakeholder discussion on the implications of climate change for water management in the region. The paper describes two main objectives: (a) providing a set of research products that will be of relevance to regional interests in the Okanagan, and (b) establishing a methodology for participatory integrated assessment of regional climate change impacts and adaptation that could be applied to climate-related concerns in Canada and other countries. This collaborative study has relied on field research, computer-based models, and dialogue exercises to generate an assessment of future implications, and to learn about regional views on the prospects for adaptation. Along the way, it has benefited from strong partnerships with governments, researchers, local water practitioners, and user groups. Building on the scenario-based study components, and a series of interviews and surveys undertaken for the water management and adaptation case study components, a set of stakeholder dialogue sessions were organized which focused on identifying preferred adaptation options and processes for their implementation. Rather than seeking consensus on the “best” option or process, regional interests were asked to consider a range of available options as part of an adaptation portfolio that could address both supply side and demand side aspects of water resources management in the Okanagan. The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.  相似文献