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31.
Institutional ambiguity in implementing the European Union Marine Strategy Framework Directive 总被引:1,自引:0,他引:1
This article addresses the institutional ambiguity that exists between the European, Regional and Member State levels in the implementation of the Marine Strategy Framework Directive (MSFD). The two main reasons for the emergence of institutional ambiguity are (1) the MSFD being a framework directive and (2) Member States are required to coordinate the implementation of the MFSD through the Regional Sea Conventions. Institutional ambiguity refers to the interference zone between different institutional settings that come together in new policy practices. New rules of the game are needed to bring these institutional settings together and the room to manoeuvre for the actors who negotiate these rules is a defining feature of institutional ambiguity. This article analyses the institutional ambiguity associated with MSFD implementation on the European and regional level for four European Seas: the North Sea, the Baltic Sea, the Mediterranean Sea and the Black Sea. The results indicate different levels of institutional ambiguity in each of the four regions, with the lowest level of ambiguity in the Baltic Sea and the highest in the Mediterranean Sea. Institutional ambiguity also exists on the European level, as coordination efforts have not resulted in clear directions for the implementation of the MSFD as yet. The level of institutional ambiguity is influenced by the relative number of EU member states bordering the particular sea and whether they consider implementation of the MFSD to be urgent. Member States bordering the Mediterranean and the Black Seas lack the support of Regional Sea Conventions in addition to receiving limited direction from the European level. 相似文献
32.
Velocity analysis based on data correlation 总被引:1,自引:0,他引:1
Several methods exist to automatically obtain a velocity model from seismic data via optimization. Migration velocity analysis relies on an imaging condition and seeks the velocity model that optimally focuses the migrated image. This approach has been proven to be very successful. However, most migration methods use simplified physics to make them computationally feasible and herein lies the restriction of migration velocity analysis. Waveform inversion methods use the full wave equation to model the observed data and more complicated physics can be incorporated. Unfortunately, due to the band‐limited nature of the data, the resulting inverse problem is highly nonlinear. Simply fitting the data in a least‐squares sense by using a gradient‐based optimization method is sometimes problematic. In this paper, we propose a novel method that measures the amount of focusing in the data domain rather than the image domain. As a first test of the method, we include some examples for 1D velocity models and the convolutional model. 相似文献
33.
Joeri van Leeuwen Robert D. Ferdman Sol Meyer Ingrid Stairs 《Monthly notices of the Royal Astronomical Society》2007,374(4):1437-1440
Low-mass white dwarfs can be produced either in low-mass X-ray binaries by stable mass transfer to a neutron star, or in a common envelope phase with a heavier white dwarf companion. We have searched eight low-mass white dwarf candidates recently identified in the Sloan Digital Sky Survey for radio pulsations from pulsar companions, using the Green Bank Telescope at 340 MHz. We have found no pulsations down to flux densities of 0.6–0.8 mJy kpc−2 and conclude that a given low-mass helium-core white dwarf has a probability of <0.18 ± 0.05 of being in a binary with a radio pulsar. 相似文献
34.
D. L. Harrison F. van Leeuwen 《Monthly notices of the Royal Astronomical Society》2006,365(2):699-704
The geometric calibration of the Planck satellite using the planetary transits is investigated, together with the reconstruction of any offsets from the nominal layout of the focal plane. The methods presented here may be applied to a single focal plane transit of a planet, to find the values of the geometric-calibration parameters at the epoch of the transit or all the transits over the course of the mission. The pointing requirements are easily met, with the pointing reconstruction being dominated by the errors due to the star tracker. 相似文献
35.
In this paper, we develop the triangle of marine governance to understand the changing locus and focus of marine governance practices. In general, the locus and focus of marine governance is shifting from top-down, state-led governance to network governance. This shift is captured by the triangle of marine governance, because the triangle refers to the institutional setting in which politics and policy making takes place (polity), to policy making itself (policy), to activities of politicians and processes of power (politics), and to the interplay between policy, politics and polity. Studying the dynamics of politics and policies in marine governance practices through the triangle allows us to analyze and explain how and why the shifts in locus and focus occur. These dynamics of marine governance—as the interplay of policy, politics and policy—is illustrated by the environmental governance of Dutch offshore platforms. 相似文献
36.
Sabine Miehe Georg Miehe Jacqueline F. N. van Leeuwen Claudia Wrozyna Willem O. van der Knaap La Duo Torsten Haberzettl 《Journal of Paleolimnology》2014,51(2):267-285
The closed Tangra Yumco Basin underwent the strongest Quaternary lake-level changes so far recorded on the Tibetan Plateau. It was hitherto unknown what effect this had on local Holocene vegetation development. A 3.6-m sediment core from a recessional lake terrace at 4,700 m a.s.l., 160 m above the present lake level of Tangra Yumco, was studied to reconstruct Holocene flooding phases (sedimentology and ostracod analyses), vegetation dynamics and human influence (palynology, charcoal and coprophilous fungi analyses). Peat at the base of the profile proves lake level was below 4,700 m a.s.l. during the Pleistocene/Holocene transition. A deep-lake phase started after 11 cal ka BP, but the ostracod record indicates the level was not higher than ~4,720 m a.s.l. (180 m above present) and decreased gradually after the early Holocene maximum. Additional sediment ages from the basin suggest recession of Tangra Yumco from the coring site after 2.6 cal ka BP, with a shallow local lake persisting at the site until ~1 cal ka BP. The final peat formation indicates drier conditions thereafter. Persistence of Artemisia steppe during the Holocene lake high-stand resembles palynological records from west Tibet that indicate early Holocene aridity, in spite of high lake levels that may have resulted from meltwater input. Yet pollen assemblages indicate humidity closer to that of present potential forest areas near Lhasa, with 500–600 mm annual precipitation. Thus, the early mid-Holocene humidity was sufficient to sustain at least juniper forest, but Artemisia dominance persisted as a consequence of a combination of environmental disturbances such as (1) strong early Holocene climate fluctuations, (2) inundation of habitats suitable for forest, (3) extensive water surfaces that served as barriers to terrestrial diaspore transport from refuge areas, (4) strong erosion that denuded the non-flooded upper slopes and (5) increasing human influence since the late glacial. 相似文献
37.
S. Hussain J. van Leeuwen R. Aryal B. Sarkar C. W. K. Chow S. Beecham 《International Journal of Environmental Science and Technology》2018,15(4):847-862
One of the key challenges in water treatment industry is the removal of organic compounds by cost-effective methods. This study evaluated the adsorptive removal of dissolved organic carbon (DOC) from reservoir water using fuller’s earth (FE) in comparison with natural (SQ) and modified quartz (MSQ) sands. The removal capacities of FE at different contact times, pH levels, adsorbent dosages and initial DOC concentrations were compared with both the quartz sands. The optimum DOC removals by FE and SQs were achieved at contact time of 60 and 30 min, pH level of 6 and 4, and at adsorbent dose of 1.5 g/150 mL and 10 g/100 mL, respectively. The adsorption capacity of FE (1.05 mg/g) was much higher compared to the MSQ (0.04 mg/g) and SQ (0.01 mg/g). Adsorption equilibrium data better fitted to the Freundlich model than to the Langmuir model, suggesting that adsorption occurred primarily through multilayer formation onto the surfaces of FE and SQ. The pseudo-second-order model described the uptake kinetics more effectively than the pseudo-first-order and intra-particle diffusion models, indicating that the mechanism was primarily governed by chemisorption. These observations were well supported by the physiochemical characteristics and charge behaviour of the adsorbents. In mass-transfer study, the results of liquid film diffusion model showed that the adsorption of DOC on FE was not controlled by film diffusion, but other mechanisms also played an essential role. This study demonstrates that FE is an effective adsorbent for the removal of DOC in surface water treatment. 相似文献
38.
Lagrangian validation of numerical drifter trajectories using drifting buoys: Application to the Agulhas system 总被引:1,自引:0,他引:1
E. van Sebille P.J. van Leeuwen A. Biastoch C.N. Barron W.P.M. de Ruijter 《Ocean Modelling》2009,29(4):269-276
The skill of numerical Lagrangian drifter trajectories in three numerical models is assessed by comparing these numerically obtained paths to the trajectories of drifting buoys in the real ocean. The skill assessment is performed using the two-sample Kolmogorov–Smirnov statistical test. To demonstrate the assessment procedure, it is applied to three different models of the Agulhas region. The test can either be performed using crossing positions of one-dimensional sections in order to test model performance in specific locations, or using the total two-dimensional data set of trajectories. The test yields four quantities: a binary decision of model skill, a confidence level which can be used as a measure of goodness-of-fit of the model, a test statistic which can be used to determine the sensitivity of the confidence level, and cumulative distribution functions that aid in the qualitative analysis. The ordering of models by their confidence levels is the same as the ordering based on the qualitative analysis, which suggests that the method is suited for model validation. Only one of the three models, a 1/10° two-way nested regional ocean model, might have skill in the Agulhas region. The other two models, a 1/2° global model and a 1/8° assimilative model, might have skill only on some sections in the region. 相似文献
39.
Lucia Wick Jacqueline F.N. van Leeuwen Willem O. van der Knaap André F. Lotter 《Journal of Paleolimnology》2003,30(3):261-272
Pollen and plant macrofossils were analysed at Sägistalsee (1935 m asl), a small lake near timber-line in the Swiss Northern Alps. Open forests with Pinus cembra and Abies alba covered the catchment during the early Holocene (9000–6300 cal. BP), suggesting subcontinental climate conditions. After the expansion of Picea abies between 6300 and 6000 cal. BP the subalpine forest became denser and the tree-line reached its maximum elevation at around 2260 m asl. Charcoal fragments in the macrofossil record indicate the beginning of Late-Neolithic human impact at ca. 4400 cal. BP, followed by a extensive deforestation and lowering of the forest-limit in the catchment of Sägistalsee at 3700 cal. BP (Bronze Age). Continuous human activity, combined with a more oceanic climate during the later Holocene, led to the local extinction of Pinus cembra and Abies alba and favoured the mass expansion of Picea and Alnus viridis in the subalpine area of the Northern Alps. The periods before 6300 and after 3700 cal. BP are characterised by high erosion activity in the lake's catchment, whereas during the phase of dense Picea-Pinus cembra-Abies forests (6300–3700 cal. BP) soils were stable and sediment-accumulation rates in the lake were low. Due to decreasing land-use at higher altitudes during the Roman occupation and the Migration period, forests spread beween ca. 2000 and 1500 cal. BP, before human impact increased again in the early Middle Ages. Recent reforestation due to land-use changes in the 20th century is recorded in the top sediments. Pollen-inferred July temperature and annual precipitation suggest a trend to cooler and more oceanic climate starting at about 5500 cal. BP. 相似文献
40.
Anthony D.Challinor Daniel J.Mortlock Floorvan Leeuwen Anthony N.Lasenby Michael P.Hobson Mark A. J.Ashdown George P.Efstathiou 《Monthly notices of the Royal Astronomical Society》2002,331(4):994-1010
Despite the fact that the physics of the cosmic microwave background anisotropies is most naturally expressed in Fourier space, pixelized maps are almost always used in the analysis and simulation of microwave data. A complementary approach is investigated here, in which maps are used only in the visualization of the data, and the temperature anisotropies and polarization are only ever expressed in terms of their spherical multipoles. This approach has a number of advantages: there is no information loss (assuming a band-limited observation); deconvolution of asymmetric beam profiles and the temporal response of the instrument are naturally included; correlated noise can easily be taken into account, removing the need for additional 'destriping'; polarization is also analysed in the same framework; and reliable estimates of the spherical multipoles of the sky and their errors are obtained directly for subsequent component separation and power spectrum estimation. The formalism required to analyse experiments which survey the full sky by scanning on circles is derived here, with particular emphasis on the Planck mission. A number of analytical results are obtained in the limit of simple scanning strategies. Although there are non-trivial computational obstacles to be overcome before the techniques described here can be implemented at high resolution, if these can be overcome the method should allow for a more robust return from the next generation of full-sky microwave background experiments. 相似文献