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41.
Floodplains are characterized by high spatial and temporal heterogeneity. Despite low active mobility, Central European floodplain gastropod communities show a high species diversity. They are supposed to have developed a large range of resistance and/or resilience strategies to survive in the highly variable and frequently disturbed floodplain habitats. Relating gastropod diversity and species traits to hydrological conditions, we tested how different groundwater and flood regimes affect gastropod diversity and identified the main species traits favouring their survival in highly dynamic floodplain grasslands. Species richness, species diversity and functional diversity peaked at intermediate flood disturbance and moisture levels. Harsher environmental conditions in either dryer or frequently flooded habitats restricted the gastropod communities to a few specialized species. Morphological and life‐history traits showed significant variations along the hydrological gradient. Shell character and mode of reproduction proved to be important functional determinants for gastropod community composition. Species with strongly calcified shells, which limit the risk of injuries in case of dislodgment, were more often found in flood prone sites. Uniparental reproduction dominated in the driest as well as in highly flood‐disturbed habitats, providing reproductive assurance where harsh environmental conditions may reduce the number of potential mates. Intermediate disturbance and moisture levels favoured local gastropod diversity whereas dryer or highly flood‐disturbed habitats sheltered specialized species. Therefore, the maintenance of areas with different disturbance and moisture levels is of major importance in favouring taxonomical and functional mollusc diversity across the whole floodplain. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
42.
The role of housing adjustment costs in influencing mobility decisions, and the relationship between these and housing demands is not well understood. Here we try to examine how changes in adjustment costs as well as in such demand factors as income, influence the decision of households to adjust their housing consumption through moving. Empirically, we use a sample of recently moving homeowners from the PSID and provide evidence indicating adjustment costs are more important than other demand factors in influencing mobility decisions. We also argue that sample selection may bias estimates of housing demand elasticities when the sample is restricted to recent movers because the influence of adjustment costs in the mobility decision are not accounted for. Testing for this using the Heckman two-stage procedure, however, showed this was not a significant problem. 相似文献
43.
Prof. Oskar Anderson Prof. Wilhelm Winkler Prof. Hans Kellerer Prof. Slawtscho Sagoroff 《Metrika》1958,1(1):1-2
Ohne Zusammenfassung 相似文献
44.
Empirica - Almost 20% of all male employees in Germany who become unemployed return to their previous employers. Such temporary layoffs and the subsequent recalls are often used by firms to shift... 相似文献
45.
Iftekhar Hasan Krzysztof Jackowicz Oskar Kowalewski Łukasz Kozłowski 《Journal of Banking & Finance》2013
The Central European banking industry is dominated by foreign-owned banks. During the recent crisis, for the first time since the transition, foreign parent companies were frequently in a worse financial condition than their subsidiaries. This situation created a unique opportunity to study new aspects of market discipline exercised by non-financial depositors. Using a comprehensive data set, we find that the recent crisis did not change the sensitivity of deposit growth rates to accounting risk measures. We establish that depositors’ actions were more strongly influenced by negative press rumors concerning parent companies than by fundamentals. The impact of rumors was especially perceptible when rumors turned out ex post to be founded. Additionally, we document that public aid announcements were primarily interpreted by depositors as confirmation of a parent company’s financial distress. Our results indicate that depositors react rationally to sources of information other than financial statements; this discovery has policy implications, as depositor discipline is usually the only viable and universal source of market discipline for banks in emerging economies. 相似文献
46.
47.
Oskar Morgenstern 《Journal of Economics》1932,3(2):251-255
Ohne ZusammenfassungDie Untersuchung wurde im Österreichischen Institut für Konjunkturforschung angestellt. Der Verfasser ist Frau St. Hainzer für unermüdliche Unterstützung bei der Ausarbeitung zu Dank verpflichtet. 相似文献
48.
TEMPEST is a new interactive simulation program for the estimation of the wastewater temperature in sewers. Intuitive graphical user interfaces assist the user in managing data, performing calculations and plotting results. The program calculates the dynamics and longitudinal spatial profiles of the wastewater temperature in sewer lines. Interactions between wastewater, sewer air and surrounding soil are modeled in TEMPEST by mass balance equations, rate expressions found in the literature and a new empirical model of the airflow in the sewer. TEMPEST was developed as a tool which can be applied in practice, i.e., it requires as few input data as possible. These data include the upstream wastewater discharge and temperature, geometric and hydraulic parameters of the sewer, material properties of the sewer pipe and surrounding soil, ambient conditions, and estimates of the capacity of openings for air exchange between sewer and environment. Based on a case study it is shown how TEMPEST can be applied to estimate the decrease of the downstream wastewater temperature caused by heat recovery from the sewer. Because the efficiency of nitrification strongly depends on the wastewater temperature, this application is of practical relevance for situations in which the sewer ends at a nitrifying wastewater treatment plant. 相似文献
49.
In a bioelectrochemical system, the energy content in dissolved organic matter can be used to power the production of hydrogen peroxide (H(2)O(2)), which is a potentially useful chemical at wastewater treatment plants. H(2)O(2) can be produced by the cathodic reduction of oxygen. We investigated four types of gas-diffusion electrodes (GDEs) for this purpose. A GDE made of carbon nanoparticles bound with 30% polytetrafluoroethylene (PTFE) (wt./wt.C) to a carbon fiber paper performed best and catalyzed H(2)O(2) production from oxygen in air with a coulombic efficiency of 95.1%. We coupled the GDE to biological anodes in two bioelectrochemical reactors. When the anodes were fed with synthetic wastewater containing acetate they generated a current of up to ~0.4 mA/mL total anode compartment volume. H(2)O(2) concentrations of ~0.2 and ~0.5% could be produced in 5 mL catholyte in 9 and 21 h, respectively. When the anodes were fed with real wastewater, the generated current was ~0.1 mA/mL and only 84 mg/L of H(2)O(2) was produced. 相似文献
50.