Refine
Year of publication
Document Type
- Article (16363)
- Part of Periodical (2825)
- Working Paper (2365)
- Preprint (2319)
- Doctoral Thesis (2082)
- Book (1738)
- Conference Proceeding (1235)
- Part of a Book (1071)
- Report (471)
- Review (166)
Language
- English (30833) (remove)
Keywords
- taxonomy (752)
- new species (451)
- morphology (180)
- Deutschland (142)
- Syntax (126)
- Englisch (120)
- distribution (118)
- biodiversity (104)
- inflammation (101)
- Deutsch (98)
Institute
- Medizin (5467)
- Physik (4299)
- Wirtschaftswissenschaften (1941)
- Frankfurt Institute for Advanced Studies (FIAS) (1883)
- Biowissenschaften (1574)
- Informatik (1522)
- Center for Financial Studies (CFS) (1506)
- Biochemie und Chemie (1097)
- Sustainable Architecture for Finance in Europe (SAFE) (1085)
- House of Finance (HoF) (718)
Balloon-borne stratospheric BrO measurements: comparison with Envisat/SCIAMACHY BrO limb profiles
(2006)
For the first time, results of all four existing stratospheric BrO profiling instruments, are presented and compared with reference to the SLIMCAT 3-dimensional chemical transport model (3-D CTM). Model calculations are used to infer a BrO profile validation set, measured by 3 different balloon sensors, for the new Envisat/SCIAMACHY (ENVIronment SATellite/SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) satellite instrument. The balloon observations include (a) balloon-borne in situ resonance fluorescence detection of BrO, (b) balloon-borne solar occultation DOAS measurements (Differential Optical Absorption Spectroscopy) of BrO in the UV, and (c) BrO profiling from the solar occultation SAOZ (Systeme d'Analyse par Observation Zenithale) balloon instrument. Since stratospheric BrO is subject to considerable diurnal variation and none of the measurements are performed close enough in time and space for a direct comparison, all balloon observations are considered with reference to outputs from the 3-D CTM. The referencing is performed by forward and backward air mass trajectory calculations to match the balloon with the satellite observations. The diurnal variation of BrO is considered by 1-D photochemical model calculation along the trajectories. The 1-D photochemical model is initialised with output data of the 3-D model with additional constraints on the vertical transport, the total amount and photochemistry of stratospheric bromine as given by the various balloon observations. Total [Bry]=(20.1±2.8)pptv obtained from DOAS BrO observations at mid-latitudes in 2003, serves as an upper limit of the comparison. Most of the balloon observations agree with the photochemical model predictions within their given error estimates. First retrieval exercises of BrO limb profiling from the SCIAMACHY satellite instrument agree to <±50% with the photochemically-corrected balloon observations, and tend to show less agreement below 20 km.
During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35° N and 75° N in the European longitude sector (10° W–20° E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N2O, CH4, CO, CO2, CFC12, H2, SF6, NO, NOy, O3 and H2O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature – equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O3 and NOy and the lowest mixing ratios of N2O and SF6. The lowest mixing ratios of NOy and O3 are observed during autumn, together with the highest mixing ratios of N2O and SF6 indicating a strong tropospheric influence. For H2O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies.
During several balloon flights inside the Arctic polar vortex in early 2003, unusual trace gas distributions were observed, which indicate a strong influence of mesospheric air in the stratosphere. The tuneable diode laser (TDL) instrument SPIRALE (Spectroscopie InFrarouge par Absorption de Lasers Embarqués) measured unusually high CO values (up to 600 ppb) on 27 January at about 30 km altitude. The cryosampler BONBON sampled air masses with very high molecular Hydrogen, extremely low SF6 and enhanced CO values on 6 March at about 25 km altitude. Finally, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) Fourier Transform Infra-Red (FTIR) spectrometer showed NOy values which are significantly higher than NOy* (the NOy derived from a correlation between N2O and NOy under undisturbed conditions), on 21 and 22 March in a layer centred at 22 km altitude. Thus, the mesospheric air seems to have been present in a layer descending from about 30 km in late January to 25 km altitude in early March and about 22 km altitude on 20 March. We present corroborating evidence from a model study using the KASIMA (KArlsruhe Simulation model of the Middle Atmosphere) model that also shows a layer of mesospheric air, which descended into the stratosphere in November and early December 2002, before the minor warming which occurred in late December 2002 lead to a descent of upper stratospheric air, cutting of a layer in which mesospheric air is present. This layer then descended inside the vortex over the course of the winter. The same feature is found in trajectory calculations, based on a large number of trajectories started in the vicinity of the observations on 6 March. Based on the difference between the mean age derived from SF6 (which has an irreversible mesospheric loss) and from CO2 (whose mesospheric loss is much smaller and reversible) we estimate that the fraction of mesospheric air in the layer observed on 6 March, must have been somewhere between 35% and 100%.
A new version of a digital global map of irrigation areas was developed by combining irrigation statistics for 10 825 sub-national statistical units and geo-spatial information on the location and extent of irrigation schemes. The map shows the percentage of each 5 arc minute by 5 arc minute cell that was equipped for irrigation around the year 2000. It is thus an important data set for global studies related to water and land use. This paper describes the data set and the mapping methodology and gives, for the first time, an estimate of the map quality at the scale of countries, world regions and the globe. Two indicators of map quality were developed for this purpose, and the map was compared to irrigated areas as derived from two remote sensing based global land cover inventories.
Flow velocity in rivers has a major impact on residence time of water and thus on high and low water as well as on water quality. For global scale hydrological modeling only very limited information is available for simulating flow velocity. Based on the Manning-Strickler equation, a simple algorithm to model temporally and spatially variable flow velocity was developed with the objective of improving flow routing in the global hydrological model of Water- GAP. An extensive data set of flow velocity measurements in US rivers was used to test and to validate the algorithm before integrating it into WaterGAP. In this test, flow velocity was calculated based on measured discharge and compared to measured velocity. Results show that flow velocity can be modeled satisfactorily at selected river cross sections. It turned out that it is quite sensitive to river roughness, and the results can be optimized by tuning this parameter. After the validation of the approach, the tested flow velocity algorithm has been implemented into the WaterGAP model. A final validation of its effects on the model results is currently performed.
Event-by-event fluctuations of the net baryon number and electric charge in nucleus-nucleus collisions are studied in Pb+Pb at SPS energies within the HSD transport model. We reveal an important role of the fluctuations in the number of target nucleon participants. They strongly influence all measured fluctuations even in the samples of events with rather rigid centrality trigger. This fact can be used to check different scenarios of nucleus-nucleus collisions by measuring the multiplicity fluctuations as a function of collision centrality in fixed kinematical regions of the projectile and target hemispheres. The HSD results for the event-by-event fluctuations of electric charge in central Pb+Pb collisions at 20, 30, 40, 80 and 158 A GeV are in a good agreement with the NA49 experimental data and considerably larger than expected in a quark-gluon plasma. This demonstrate that the distortions of the initial fluctuations by the hadronization phase and, in particular, by the final resonance decays dominate the observable fluctuations.
We obtain the D-meson spectral density at finite temperature for the conditions of density and temperature expected at FAIR. We perform a self-consistent coupled-channel calculation taking, as a bare interaction, a separable potential model. The Lambda_c (2593) resonance is generated dynamically. We observe that the D-meson spectral density develops a sizeable width while the quasiparticle peak stays close to the free position. The consequences for the D-meson production at FAIR are discussed.
The sovereignty of the European nation states in the realm of security politics is gradually eroding. At the same time the European integration to a large degree influences the level of direct bilateral police cooperation, since cross-border crime has come to be perceived not as only a national, but as a common problem for the European nation states. At the German-Polish border, "Europe's Rio Grande", these high expectations concerning security policy are put into practice. With Poland's EU accession, Polish and German border guards are no longer spatially separated, but jointly control travellers. Joint patrols and contact points have already existed since 1998. On the one hand, the enforced meeting of German and Polish border policemen may help dismantle mutual prejudices. On the other hand, other cleavages may appear, based on cultural, systemic and institutional factors, which hinder the development of mutual trust and reinforce the asymmetrical relationship between the Schengen member Germany and the "junior partner" Poland.
After more than a decade of post-socialist transition, transition theories are increasingly criticised for their inability to grasp the new post-socialist reality. However, even in the light of political, economic, social and cultural restructuring processes taking place on a global scale, the structural legacies of socialist and pre-socialist development are not erased. On the contrary, they continue to play an important role by filtering the impact of global tendencies upon post-socialist societies. With reference to a case study from the Romanian city of Timisoara I will address in the following the ambivalencies connected to the efforts of local elites in the process of implementing global-level requirements in a post-socialist environment.
During the past decade, processes associated with what is popularly though perhaps misleadingly known as globalization have come within the purview of anthropology. Migration and mobility ‐ and the footloose or even rootless social groups that they produce ‐ as well as the worldwide diffusion of commodities, media images, political ideas and practices, technologies and scientific knowledge today are on anthropology's research agenda. As a consequence, received notions about the ways in which culture relates to territory have been abandoned. The term transnationalisation captures cultural processes that stream across the borders of nation states. Anthropologists have been forced to revise the notion that transnationalisation would inevitably bring about a culturally homogenized world. Instead, we are witnessing a surge of greatly increasing cultural diversity. New cultural forms grow out of historically situated articulations of the local and the global. Rather than left-over relics from traditional orders, these are decidedly modern, yet far from uniform. The essay engages the idea of the pluralization of modernities, explores its potential for interdisciplinary research agendas, and also inquires into problematic assumptions underlying this new theoretical concept.
Scientific results of the trawling expedition of H.M.C.S. "Thetis" : Crustacea, Part V., Amphipoda
(1910)
We focus on a quantitative assessment of rigid labor markets in an environment of stable monetary policy. We ask how wages and labor market shocks feed into the inflation process and derive monetary policy implications. Towards that aim, we structurally model matching frictions and rigid wages in line with an optimizing rationale in a New Keynesian closed economy DSGE model. We estimate the model using Bayesian techniques for German data from the late 1970s to present. Given the pre-euro heterogeneity in wage bargaining we take this as the first-best approximation at hand for modelling monetary policy in the presence of labor market frictions in the current European regime. In our framework, we find that labor market structure is of prime importance for the evolution of the business cycle, and for monetary policy in particular. Yet shocks originating in the labor market itself may contain only limited information for the conduct of stabilization policy. JEL - Klassifikation: J64 , E32 , C11 , E52
As of today, estimating interest rate reaction functions for the Euro Area is hampered by the short time span since the conduct of a single monetary policy. In this paper we circumvent the common use of aggregated data before 1999 by estimating interest rate reaction functions based on a panel including actual EMU Member States. We find that exploiting the cross-section dimen- sion of a multi-country panel and accounting for cross-country heterogeneity in advance of the single monetary policy pays off with regard to the estimated reaction functions' ability to describe actual interest rate dynamics. We retrieve a panel reaction function which is demonstrated to be a valuable tool for evaluating episodes of monetary policy since 1999. JEL - Klassifikation: E43 , E58 , C33
This paper investigates various theories explaining banks´ overbidding in the fixed rate tenders of the European Central Bank (ECB). Using auction data from both the Bundesbank and the ECB, we show that none of the theories can on its own explain the observed overbidding. This implies that the proposed new rules by the ECB, aimed at neutralizing interest rate expectations, would not eliminate overbidding if the rationing rule in the fixed rate tenders remains unchanged. JEL - Klassifikation: D44 , E32
Although stable money demand functions are crucial for the monetary model of the exchange rate, empirical research on exchange rates and money demand is more or less disconnected. This paper tries to fill the gap for the Euro/Dollar exchange rate. We investigate whether monetary disequilibria provided by the empirical literature on U.S. and European money demand functions contain useful information about exchange rate movements. Our results suggest that the empirical performance of the monetary exchange rate model improves when insights from the money demand literature are explicitly taken into account. JEL - Klassifikation: F31 , E41
The dynamic relationship between the Euro overnight rate, the ECB´s policy rate and the term spread
(2006)
This paper investigates how the dynamic adjustment of the European overnight rate Eonia to the term spread and the ECB’s policy rate has been affected by rate expectations and the operational framework of the ECB. In line with recent evidence found for the US and Japan, the reaction of the Eonia to the term spread is non-symmetric. Moreover, the response of the Eonia to the policy rate depends on both, the repo auction format and the position of the Eonia in the ECB’s interest rate corridor. JEL - Klassifikation: E43 , E52