The Morphology of Thin Metal Coatings Formed by Rotary Shadowing Biological Species in High Vacuum

Rotary Shadowing has been used to increase the image contrast of biological species observed during edge-projection imaging in the transmission electron microscope. In this imaging mode, biological species are adsorbed from aqueous solutions onto a highly curved substrate and viewed, over its edge, in a direction parallel to its surface. Since the substrate is not placed between a biological adsorbate and the photographic emulsion that records its image, any material can be used as a support (including high-Z metals and semiconductors). Binding to these technologically interesting materials is observed with unusual clarity and contrast, even at 200kV. Individual adsorbates and multilayer structures are clearly delineated by a thin, metal shadow layer that surrounds them. As expected, gold and platinum form rough, discontinuous and coarse grained layers, while tungsten layers are smooth, continuous and fine grained on a subnanometer scale. Edge-projection imaging, in conjunction with rotary shadowing, is providing a unique view of shadow layer morphology, and the first images of protein molecules, virus particles, and multilayers formed by the immune reaction

Sensitivity analysis by the adjoint chemistry transport model DRAISfor an episode in the Berlin Ozone (BERLIOZ) experiment

International audienceThe Berlin Ozone Experiment (BERLIOZ) was carried out in summer 1998. One of its purposes was the evaluation of Chemistry Transport Models (CTM). CTM KAMM/DRAIS was one of the models considered. The data of 20 July were selected for evaluation. On that day, a pronounced ozone plume developed downwind of the city. Evaluation showed that the KAMM/DRAIS model is able to reproduce the meteorological and ozone data observed, except at farther distances (60?80 km) downwind of the city. In that region, the DRAIS model underestimates the measured ozone concentrations by 10?15 ppb, approximately. Therefore, this study was conducted to detect possible reasons for this deviation. A comprehensive sensitivity analysis was carried out to determine the most relevant model parameters. The adjoint DRAIS model was developed for this purpose, because for this study the application of this model is the most effective method of calculating the sensitivities. The least squares of the measured and simulated ozone concentrations between 08:00 UTC and 16:00 UTC at two stations 30 km and 70 km downwind of the city centre were chosen as distance function. The model parameters considered in this study are the complete set of initial and boundary species concentrations, emissions, and reaction rates, respectively. A sensitivity ranking showing the relevance of the individual parameters in the set is determined for each parameter set. In order to find out which modification in the parameter sets most reduces the cost function, simplified 4-D data assimilation was carried out. The result of this data assimilation shows that modifications of the reaction rates provide the best agreement between the measured and the simulated ozone concentrations at both stations. However, the modified reaction rates seem to be unrealistic for the whole simulation period. Therefore, the good agreement should not be overestimated. The agreement is still acceptable when the parameters in the other sets are modified together. The investigation demonstrates that an analysis of this type can help to explain inconsistencies between observations and simulations. But in the case considered here the inconsistencies cannot be explained by an error in only one parameter set

Null objects in Brazilian Portuguese, revisited

Authors studying the null object in Brazilian Portuguese generally distinguish two classes of sentences: those in which the verb preceding the null object is identical to the verb which precedes the null object’s antecedent, and those in which these two verbs are distinct. The present study examines the latter class of sentences. On the basis of novel empirical evidence, it is argued that this class admits two distinct derivations: one, in which the null object is pro, and the other, in which the null object is derived via ellipsis. It is further argued that both derivations are available independent of whether the null object is embedded within a coordinate structure.Autores que investigam o objeto nulo no português brasileiro geralmente distinguem duas classes de sentenças: aquelas em que o verbo que precede o objeto nulo é idêntico ao verbo que precede o antecedente do objeto nulo, e aquelas em que os dois verbos são distintos. O presente estudo examina a última classe de sentenças. Com base em novas evidências empíricas, este trabalho argumenta que esta classe admite duas derivações distintas: uma em que o objeto nulo é pro, e outra em que o objeto nulo é derivado por elipse. Adicionalmente, este trabalho argumenta que ambas as derivações estão disponíveis, independentemente de o objeto nulo estar em uma estrutura coordenada

Climate change projections for CORDEX-Africa with COSMO-CLM regional climate model and differences with the driving global climate models

In the framework of the coordinated regional climate downscaling experiment (CORDEX), an ensemble of climate change projections for Africa has been created by downscaling the simulations of four global climate models (GCMs) by means of the consortium for small-scale modeling (COSMO) regional climate model (RCM) (COSMO-CLM, hereafter, CCLM). Differences between the projected temperature and precipitation simulated by CCLM and the driving GCMs are analyzed and discussed. The projected increase of seasonal temperature is found to be relatively similar between GCMs and RCM, although large differences (more than 1 °C) exist locally. Differences are also found for extreme-event related quantities, such as the spread of the upper end of the maximum temperature probability distribution function and, in turn, the duration of heat waves. Larger uncertainties are found in the future precipitation changes; this is partly a consequence of the inter-model (GCMs) variability over some areas (e.g. Sahel). However, over other regions (e.g. Central Africa) the rainfall trends simulated by CCLM and the GCMs show opposite signs, with CCLM showing a significant reduction in precipitation at the end of the century. This uncertain and sometimes contrasting behaviour is further investigated by analyzing the different models’ response to the land–atmosphere interaction and feedback. Given the large uncertainty associated with inter-model variability across GCMs and the reduced spread in the results when a single RCM is used for downscaling, we strongly emphasize the importance of exploiting fully the CORDEX-Africa multi-GCM/multi-RCM ensemble in order to assess the robustness of the climate change signal and, possibly, to identify and quantify the many sources of uncertainty that still remain

Low energy ion erosion studies of machine faceted stainless steel

Type 304 annealed stainless steel substrates with a variety of machine faceted surface finishes have been eroded by low energy (250 to 1000 eV) hydrogen, and argon ion beams. The dimensions of the machine faceted features studied range from that of the annealed crystalline grain size (approximately 0.0125 cm) to 0.25 cm macro-structures. Relative erosion rates have been measured and analyzed as a separable function of angular dependent sputtered particle emission and particle recapture. It was found that the formation of a faceted topography on the surface of components exposed to low energy, light-ion erosion can significantly reduce the effective ion erosion yield

Surface modification by ion chemical and physical erosion

Physical and chemical ion erosion surface interactions were observed for various elements and composite materials including Si, B, C, TiB/sub 2/, WC-Co cermet, and stainless steel samples which have been bombarded by low energy (50 eV-1800 eV) hydrogen ions. The erosion yield characteristics where both chemical erosion and physical erosion can occur, can be compared to the yield characteristics for the same materials bombarded by xenon which results in physical sputtering

Evaluation of the Inheritance of the Complex Vertebral Malformation Syndrome by Breeding Studies

To investigate the congenital complex vertebral malformation syndrome (CVM) in Holstein calves, two breeding studies were performed including 262 and 363 cows, respectively. Cows were selected from the Danish Cattle Database based on pedigree and insemination records. Selected cows were progeny of sires with an established heterozygous CVM genotype and pregnant after insemination with semen from another sire with heterozygous CVM genotype. Following calving the breeders should state, if the calf was normal and was requested to submit dead calves for necropsy. In both studies, significantly fewer CVM affected calves than expected were obtained; a finding probably reflecting extensive intrauterine mortality in CVM affected foetuses. The findings illustrate increased intrauterine mortality as a major potential bias in observational studies of inherited disorders