Aluminum-26 in meteorites—VII. Ureilites,their unique radiation history

Cosmogenic ²⁶A1 activities have been measured by γ-γ coincidence counting in the three ureilites which had not previously been studied. The values in dpm/kg are: Dingo Pup Donga, 38.4 ± 2.4; North Haig, 39.3 ± 4.8; Dyalpur, 55.8 ± 4.8. Five of the six known ureilites thus have lower ²⁶A1 contents, 63 per cent to 77 per cent, than the calculated saturation values, in marked contrast to most other stony meteorites. This cannot be attributed to short cosmic ray exposure ages. Nor do size and depth effects account for the narrow range of ²⁶A1 activities, because a nuclear particle track study indicates that preatmospheric radii were highly variable, from ≥ 40 cm for Goalpara to only a few cm for Dingo Pup Donga. By default, the most likely explanation is that the ureilites had much smaller or much larger orbits than all other stony meteorites.     

Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing

The present paper describes the analysis and modeling of the South China Sea (SCS) temperature cycle on a seasonal scale. It investigates the possibility to model this cycle in a consistent way while not taking into account tidal forcing and associated tidal mixing and exchange. This is motivated by the possibility to significantly increase the model’s computational efficiency when neglecting tides. The goal is to develop a flexible and efficient tool for seasonal scenario analysis and to generate transport boundary forcing for local models. Given the significant spatial extent of the SCS basin and the focus on seasonal time scales, synoptic remote sensing is an ideal tool in this analysis. Remote sensing is used to assess the seasonal temperature cycle to identify the relevant driving forces and is a valuable source of input data for modeling. Model simulations are performed using a three-dimensional baroclinic-reduced depth model, driven by monthly mean sea surface anomaly boundary forcing, monthly mean lateral temperature, and salinity forcing obtained from the World Ocean Atlas 2001 climatology, six hourly meteorological forcing from the European Center for Medium range Weather Forecasting ERA-40 dataset, and remotely sensed sea surface temperature (SST) data. A sensitivity analysis of model forcing and coefficients is performed. The model results are quantitatively assessed against climatological temperature profiles using a goodness-of-fit norm. In the deep regions, the model results are in good agreement with this validation data. In the shallow regions, discrepancies are found. To improve the agreement there, we apply a SST nudging method at the free water surface. This considerably improves the model’s vertical temperature representation in the shallow regions. Based on the model validation against climatological in situ and SST data, we conclude that the seasonal temperature cycle for the deep SCS basin can be represented to a good degree. For shallow regions, the absence of tidal mixing and exchange has a clear impact on the model’s temperature representation. This effect on the large-scale temperature cycle can be compensated to a good degree by SST nudging for diagnostic applications.     

Calculating activity coefficients in hydrometallurgy — A review

Recent developments for estimating activity coefficients of electrolytes both in pure and multicomponent aqueous solutions are reviewed with good success generally attained up to saturation. Examples are presented to illustrate applications of these methods in calculating ion concentrations, vapor pressures, and solubility limits, for some problems encountered in hydrometallurgy.     

Stresses in column-supported hyperboloidal shells subject to seismic loading

The computation of stresses within a finite element displacement method analysis of a shell of revolution is considered. The common procedure of applying the kinematic and constitutive laws to the displacement functions is examined and justified for models where the displacements are represented by high-order polynomial expansions. Also, two alternative computational formats within this technique are explored. The influence of the column-supported base condition on a hyperboloidal shell of revolution is studied with respect to the stresses calculated from a response spectrum analysis. These studies emphasize the importance of accurately modelling the base region of a column-supported shell such as a hyperbolic cooling tower.     

The Decline and Restoration of a Coastal Lagoon (Lake Veere) in the Dutch Delta

The former tidal inlet Lake Veere was turned into a stagnant brackish lake in 1961. Ever since, the system has shown a continuous degradation. The current study shows the monitoring results for the macrozoobenthic communities and the abiotic conditions for the period 1990–2008. This includes the first step to remediation, the restoration of the exchange between the tidal marine Eastern Scheldt and Lake Veere in 2004. A continuous decline in water clearance co-occurring with decreasing macrofauna densities and richness was observed till 2004. Water quality (e.g., secchi depth, nutrient levels, and oxygen conditions) improved significantly after the measure at a higher salinity level with less variation. But the macrofauna densities, biomass, and diversity did not improve yet. First indications of changes in the benthic communities by arrival of new and returning species are however observed and show that restoration at macrofauna level follows the improved abiotic conditions with a delay of several years.     

The cityscapes of European capital cities

Capital cities are politico-administrative centers. They are command centers, they symbolize authority and also the unit that is governed. Primarily they are capitals of states, but other governance systems may also have capitals. In the European context there are now regional capital cities and at least the concept of a European capital. Particularly on account of their symbolic function but also for the uses made of its appearance in political life, the cityscape of capital cities is an interesting topic for research. There are different types of capital cities in Europe that give rise to different cityscapes. Existing urban networks and types of political regime are important in this respect. Although cityscapes are pretty stable, they are differently perceived over time and uses made of them also change. A research agenda for this intersection of historical, cultural and political geography should concentrate on the evolution of these cityscapes, their perception and the uses made of them in the acting out of politics.