Description: ABSTRACT Riffle-pool sequences are a common feature of gravel-bed rivers. However, mechanisms of their generation and maintenance are still not fully understood. In this study a monitoring approach similar to the one of Andrews (1979 and 1982) is employed. It focuses on analysing cross-sectional and longitudinal channel geometry of a large floodplain river (Vereinigte Mulde, Sachsen-Anhalt, Germany) with a high temporal and spatial resolution, in order to conclude from stage-dependant morphometric changes to riffle and pool maintaining processes. In accordance with Richards (1976a), Andrews (1979 and 1982) among others, pool cross sections of the Mulde River are narrow and riffle cross sections are wide suggesting that they should rather be addressed as two general types of channel cross-sections than solely as bedforms. At high flows, riffles and pools in the study reaches changed in length and height but not in position. Pools were scoured and riffles aggraded, a development which was reversed during receding flows below the threshold of 0.4·Q bf (40% bankfull discharge). An index for the longitudinal amplitude of riffle-pool sequences, the bed undulation intensity or bedform amplitude, is introduced and proved to be highly significant as a form parameter, its first derivative as a process parameter. The process of pool scour and riffle fill is addressed as bedform maintenance or bedform accentuation. It is indicated by increasing longitudinal bed amplitudes. According to the observed dynamics of bed amplitudes, maintenance of riffle-pool sequences lags behind discharge peaks. Maximum bed amplitudes may be reached with a delay of several days after peak discharges. Increasing bed undulation intensity is interpreted to indicate bed mobility. Post-flood decrease of the bed undulation intensity indicates a retrograde phase when transport from pools to riffles has ceased and bed mobility is restricted to riffle tails and heads of pools. This type of transport behaviour is referred to as disconnected mobility. The comparison of two river reaches, one with undisturbed sediment supply, the other with sediment deficit, suggests that high bed undulation intensity values at low flows indicate sediment deficit and potentially channel degrading conditions. It is more generally hypothesised that channel bed undulations constitute a major component of form roughness and that increased bed amplitudes are an important feature of channel bed adjustment to sediment deficit be it temporally during late floods or permanently due to a supply limitation of bedload. Copyright © 2011 John Wiley & Sons, Ltd.

Description: Mutations in RPGRIP1L result in severe human diseases called ciliopathies. To unravel the molecular function of RPGRIP1L, we analyzed Rpgrip1l –/– mouse embryos, which display a ciliopathy phenotype and die, at the latest, around birth. In these embryos, cilia-mediated signaling was severely disturbed. Defects in Shh signaling suggested that the Rpgrip1l deficiency causes an impairment of protein degradation and protein processing. Indeed, we detected a cilia-dependent decreased proteasomal activity in the absence of Rpgrip1l. We found different proteasomal components localized to cilia and identified Psmd2, a component of the regulatory proteasomal 19S subunit, as an interaction partner for Rpgrip1l. Quantifications of proteasomal substrates demonstrated that Rpgrip1l regulates proteasomal activity specifically at the basal body. Our study suggests that Rpgrip1l controls ciliary signaling by regulating the activity of the ciliary proteasome via Psmd2.

Description: In intestinal and pyloric epithelia leucine-rich repeat-containing G protein-coupled receptor 5 ( Lgr5 )-expressing cells represent long-lived adult stem cells which give rise to all epithelial cell types including endocrine cells. Ablation of the Apc gene in Lgr5 -expressing cells leads to intestinal and pyloric adenomas. To assess whether all epithelial tumours of the gastrointestinal tract are derived from LGR5-positive stem cells we crossed Lgr5-EGFP-IRES-creER T2 mice which express EGFP and Cre recombinase driven by the Lgr5 promoter with CEA424-SV40-TAg mice which develop pyloric neuroendocrine carcinomas of epithelial origin. In 19-day-old mice, single SV40 T antigen (TAg)-positive cells were identified preferentially at the the base of pyloric glands close to the stem cell compartment. However, contrary to previous publications describing subpopulations of LGR5-positive cells in gastrointestinal neoplasia we could not detect Lgr5- EGFP-positive tumour cells in malignant lesions. The lack of expression of the Wnt target gene Lgr5 is probably not caused by suppression of Wnt signalling by TAg since β-catenin-mediated Wnt signalling, as measured by the TOPflash assay, was not inhibited. To determine the cellular origin of CEA424-SV40-TAg tumours we performed tracing experiments using Lgr5-EGFP-IRES-creERT2:CEA424-SV40-TAg:ROSA26-tdRFP mice. Following tamoxifen induction it was possible to efficiently trace the progeny of Lgr5 -expressing cells in gastrointestinal tissue via red fluorescent protein (RFP) expression. No RFP-positive tumour cells were detected even when RFP gene activation occurred in 7-day-old mice well before the appearance of TAg-positive tumour cells. Hence we conclude that Lgr5 -expressing stem cells probably do not constitute the cells-of-origin in CEA424-SV40-TAg mice. Consequently, not all epithelial tumours in the pyloric region are initiated by transformation of LGR5-positive stem cells. Thus additional long-lived LGR5-negative stem cells or progenitor cells with low turnover rate might exist in the pyloric region which can give rise to tumours.

Description: Providing enantiomerically pure products is of key importance in the fine chemicals, food, and pharmaceutical industries. A continuous preferential crystallization process is presented that allows the separation of conglomerate forming enantiomers in a stable, robust, and flexible way. This is achieved by coupling two continuous crystallizers by exchanging their clear liquid phases. Each crystallizer is connected to a suspension mill responsible for in situ seed generation through particle breakage. The dynamic and steady-state behavior of this process is extensively analyzed for racemic feed streams through process simulations, and parameter regions, which yield pure enantiomers in both crystallizers, are identified. For enriched feed streams, it is further shown when this novel flow sheet is capable of outperforming an ideal batch process in terms of solvent consumption per unit mass of desired enantiopure product produced. © 2015 American Institute of Chemical Engineers AIChE J , 61: 2810–2823, 2015

Description: We report on the calibration of the one-dimensional hydrodynamic lake model DYRESM to simulate the water temperature conditions of the pre-alpine Lake Ammersee (South-east Germany) which is representative of deep and large lakes in this region. Special focus is given to the calibration in order to reproduce the correct thermal distribution and stratification including the time of onset and duration of summer stratification. To ensure the application of the model to investigate the impact of climate change on lakes, an analysis of the model sensitivity under stepwise modification of meteorological input parameters (air temperature, wind speed, precipitation, global radiation, cloud cover, vapor pressure, and tributary water temperature) was conducted. The total mean error of the calibration results is –0.23 °C, the root mean square error amounts to 1.012 °C. All characteristics of the annual stratification cycle were reproduced accurately by the model. Additionally, the simulated deviations for all applied modifications of the input parameters for the sensitivity analysis can be differentiated in the high temporal resolution of monthly values for each specific depth. The smallest applied alteration to each modified input parameter caused a maximum deviation in the simulation results of at least 0.26 °C. The most sensitive reactions of the model can be observed through modifications of the input parameters air temperature and wind speed. Hence the results show that further investigations at Lake Ammersee, such as coupling the hydrodynamic model with chemo-dynamic models to assess the impact of changing climate on biochemical conditions within lakes, can be carried out using DYRESM. Copyright © 2012 John Wiley & Sons, Ltd.

Description: Measurements of trace metal ratios in foraminiferal calcite are routinely used to reconstruct paleoceanographic conditions. Analyses using solution-based inductively coupled plasma mass spectrometry (ICP-MS) require dissolution of the entire foraminifer shell. The potential exists for contamination from adherent clays, mineralized coatings, and other diagenetic components that confound the biogenic trace metal signal. We present results from a cleaning experiment on fossil specimens of the planktic foraminifer Orbulina universa that were cracked into several shell fragments and subjected to different cleaning protocols. We use LA-ICP-MS depth profiling to evaluate the effects of reductive, oxidative, and chelating (DTPA) cleaning protocols on shell Mg/Ca and Ba/Ca ratios. Using the natural pattern of intrashell Mg/Ca heterogeneity exhibited by O. universa , we demonstrate that reductive and oxidative cleaning can dissolve shell calcite from available surfaces, although intrashell Mg/Ca minima and maxima are unaffected. High-resolution depth profiles can be used to identify areas of heterogeneous intrashell Ba/Ca, which can be excluded from computations of whole-shell Ba/Ca. The size and density of shell pores plays a major role in the degree of contamination from sedimentary material. We demonstrate an approach for computing whole-shell Me/Ca ratios from LA-ICP-MS depth profiles that accounts for potential contamination and diagenetic overprinting.

Description: Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) 14 C analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, U.S.A. We find 14 C age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of 14 C measurements. Such age spectra have not previously been observed in the sedimentary record. Here, they indicate vigorous soil carbon turnover prior to burial, which homogenized 14 C ages within SOM across the entire thermochemical spectrum. The weighted bulk 14 C ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate 14 C ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (≪300 yr) of carbon in these soils relative to input of allochthonous carbon, indicating that the 14 C age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat 14 C ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea-level rise. This article is protected by copyright. All rights reserved.

Description: Fjords are disproportionately important for global organic carbon (OC) burial relative to their spatial extent, and may be important in sequestering atmospheric CO2, providing a negative climate feedback. Within fjords, multiple locally variable delivery mechanisms control mineral sediment deposition, which in turn modulates OC burial. Sediment and OC sources in Fiordland, New Zealand include terrigenous input at fjord heads, sediment reworking over fjord-mouth sills, and landslide events from steep fjord walls. Box cores were analyzed for sedimentary texture, sediment accumulation rate, and OC content to evaluate the relative importance of each delivery mechanism. Sediment accumulation was up to 3.4 mm/yr in proximal and distal fjord areas, with lower rates in medial reaches. X-radiograph and 210Pb stratigraphy indicate mass wasting and surface-sediment bioturbation throughout the fjords. Sediment accumulation rates are inversely correlated with %OC. Spatial heterogeneity in sediment depositional processes and rates is important when evaluating OC burial within fjords.

Description: Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.