A continuous measure of gross primary production for the conterminous United States derived from MODIS and AmeriFlux data

The quantification of carbon fluxes between the terrestrial biosphere and the atmosphere is of scientific importance and also relevant to climate-policy making. Eddy covariance flux towers provide continuous measurements of ecosystem-level exchange of carbon dioxide spanning diurnal, synoptic, seasonal, and interannual time scales. However, these measurements only represent the fluxes at the scale of the tower footprint. Here we used remotely sensed data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to upscale gross primary productivity (GPP) data from eddy covariance flux towers to the continental scale. We first combined GPP and MODIS data for 42 AmeriFlux towers encompassing a wide range of ecosystem and climate types to develop a predictive GPP model using a regression tree approach. The predictive model was trained using observed GPP over the period 2000-2004, and was validated using observed GPP over the period 2005-2006 and leave-one-out cross-validation. Our model predicted GPP fairly well at the site level. We then used the model to estimate GPP for each 1 km × 1 km cell across the U.S. for each 8-day interval over the period from February 2000 to December 2006 using MODIS data. Our GPP estimates provide a spatially and temporally continuous measure of gross primary production for the U.S. that is a highly constrained by eddy covariance flux data. Our study demonstrated that our empirical approach is effective for upscaling eddy flux GPP data to the continental scale and producing continuous GPP estimates across multiple biomes. With these estimates, we then examined the patterns, magnitude, and interannual variability of GPP. We estimated a gross carbon uptake between 6.91 and 7.33 Pg C yr^− 1 for the conterminous U.S. Drought, fires, and hurricanes reduced annual GPP at regional scales and could have a significant impact on the U.S. net ecosystem carbon exchange. The sources of the interannual variability of U.S. GPP were dominated by these extreme climate events and disturbances.     

Atomistic Visualization of Mesoscopic Whole‐Cell Simulations Using Ray‐Casted Instancing

Molecular visualization is an important tool for analysing the results of biochemical simulations. With modern GPU ray casting approaches, it is only possible to render several million of atoms interactively unless advanced acceleration methods are employed. Whole‐cell simulations consist of at least several billion atoms even for simplified cell models. However, many instances of only a few different proteins occur in the intracellular environment, which can be exploited to fit the data into the graphics memory. For each protein species, one model is stored and rendered once per instance. The proposed method exploits recent algorithmic advances for particle rendering and the repetitive nature of intracellular proteins to visualize dynamic results from mesoscopic simulations of cellular transport processes. We present two out‐of‐core optimizations for the interactive visualization of data sets composed of billions of atoms as well as details on the data preparation and the employed rendering techniques. Furthermore, we apply advanced shading methods to improve the image quality including methods to enhance depth and shape perception besides non‐photorealistic rendering methods. We also show that the method can be used to render scenes that are composed of triangulated instances, not only implicit surfaces.     

Output-sensitive 3D line integral convolution

We propose an output-sensitive visualization method for 3D line integral convolution (LIC) whose rendering speed is largely independent of the data set size and mostly governed by the complexity of the output on the image plane. Our approach of view-dependent visualization tightly links the LIC generation with the volume rendering of the LIC result in order to avoid the computation of unnecessary LIC points: early-ray termination and empty-space leaping techniques are used to skip the computation of the LIC integral in a lazy-evaluation approach; both ray casting and texture slicing can be used as volume-rendering techniques. The input noise is modeled in object space to allow for temporal coherence under object and camera motion. Different noise models are discussed, covering dense representations based on filtered white noise all the way to sparse representations similar to oriented LIC. Aliasing artifacts are avoided by frequency control over the 3D noise and by employing a 3D variant of MIPmapping. A range of illumination models is applied to the LIC streamlines: different codimension-2 lighting models and a novel gradient-based illumination model that relies on precomputed gradients and does not require any direct calculation of gradients after the LIC integral is evaluated. We discuss the issue of proper sampling of the LIC and volume-rendering integrals by employing a frequency-space analysis of the noise model and the precomputed gradients. Finally, we demonstrate that our visualization approach lends itself to a fast graphics processing unit (GPU) implementation that supports both steady and unsteady flow. Therefore, this 3D LIC method allows users to interactively explore 3D flow by means of high-quality, view-dependent, and adaptive LIC volume visualization. Applications to flow visualization in combination with feature extraction and focus-and-context visualization are described, a comparison to previous methods is provided, and a detailed performance analysis is included.     

Comparison of two rapid whole-blood tests for Helicobacter pylori infection in Chinese patients

Consecutive Chinese patients undergoing endoscopy for dyspepsia were tested for Helicobacter pylori infection by two rapid whole-blood tests: FlexPack HP (Abbott Laboratories) and Helisal One-Step (Cortecs Diagnostics). Biopsy-based tests (rapid urease test and histology) and the [13C]urea breath test were used as the "gold standard." One hundred sixty-one consecutive patients were studied, and 88 (54.7%) were confirmed to have H. pylori infection. The sensitivities, specificities, and positive and negative predictive values were 81.8%, 83.6% (P = 0.008), 85.7% (P = 0.04), and 79.2% for FlexPack HP and 84.1%, 63.0% (P = 0.008), 73.3% (P = 0.047), and 76.7% for Helisal One-Step, respectively.     

A methodical procedure for designing consumer oriented on-demand IT service propositions

IT providers are increasingly facing the challenge to adapt their previously resource oriented service portfolios in order to offer their customers services which explicitly support business processes. Such customer centric service propositions, however, seem to contradict the demand for standardized and automated operational IT processes more than traditional IT service offers, as they are even more subject to customer individual reengineering efforts due to permanently changing business requirements. In order to reconcile increased efficiency in operational processes and effectiveness in consumer oriented service propositions, we propose (1) to predefine all service propositions in consideration of both consumer oriented commitments and operational processes, and (2) to allow for standardized customization by offering a selection of complementary service propositions that extend commitments regarding customer oriented functionality and performance. Such service propositions are aligned with a company’s entities such as workplaces. Thereby the customer organization is enabled to trace, control and adjust commitments, value and expenses of IT services per entity in its business. We introduce a procedural model for designing and on-demand requesting this kind of service propositions, and we illustrate the model’s application and impact by examples taken from two large projects with an associated IT provider.     

Influence of Mould Materials on the Morphological and Mechanical Properties of Injection‐Moulded Prototypes

The use of prototype moulds made with rapid tooling (RT)‐techniques offers the possibility to manufacture prototypes in the series process. Although the series material is used during injection moulding, the properties of the prototype are not identical with the product because of the varying surface qualities of the RT‐moulds and the different thermal conditions in the process. In this work, different RT‐techniques (resin casting, metal spraying, selective laser sintering, investment casting and keltooling) are investigated according to the morphological as well as the mechanical properties of injection‐moulded prototypes. The specimen are compared with parts that were injection‐moulded in a steel mould to realise a comparison between prototype and product. The thermal diffusivity of the analysed RT‐mould materials differs from one tenth of the value of steel up to seven times higher compared to steel. This leads to a different morphology of the prototype concerning the boundary layers and the spherulite size. A good heat conducting material (e. g. aluminium investment casting mould) causes thick boundary layers and small spherulites. In contrast, a rather insulating mould material (e. g. resin casting mould) results in thin boundary layers and large spherulites. The investigations show that the effect of a good heat conducting material can be achieved by using a lower mould temperature for badly conducting materials in the same way. The yield stress of the prototypes differs up to 20% from the mechanical properties of the product and is influenced by the spherulite size and the mould's surface quality. The prototype, moulded in a keltool mould, shows the best resemblance with the product.     

Vergleichende Untersuchungen über die gas-chromatographischen Trenneigenschaften der Polyester aus Äthylenglykol und aliphatischen Dicarbonsäuren

Comparative Studies on the Gas Chromatographic Resolving Properties of Polyesters from Ethylene Glycol and Aliphatic Dicarboxylic Acids Ethylene glycol polyesters of aliphatic dicarboxylic acids (C₄-C₁₀) were synthesized. In the gas chromatographic analysis, the relative retention values for n-paraffins, α-n-olefins, fatty acid methyl esters, fatty alcohol acetates and dicarboxylic acid methyl esters are independent of the molecular weights and the end group distribution of the said liquid phases. With the help of the closely agreeing t_R-values GLC-Spectra were drawn, which enable a rapid identification of the compounds mentioned above with the aid of a few test substances. Mixed polyesters behave in the same way.     

Methanol synthesis from CO2 and H2 in multi-tubular fixed-bed reactor and multi-tubular reactor filled with monoliths

This work investigates the impact of catalyst structuring into particles or monoliths on methanol production from only CO₂ and H₂ at a large scale. Methanol synthesis in multi-tubular reactors is evaluated using packed-bed and monolithic reactors by modeling heat and mass transfer in each reactor. The obtained simulation results show that, at low gas hourly space velocity (GHSV = 10,000 h⁻¹), the performances of both reactor technologies are similar. In this case, the packed-bed reactor technology is the most appropriate technology due to its simplicity of installation and operation. At high GHSV (25,000 h⁻¹), the packed-bed reactor technology is limited by a considerable pressure drop that causes an important loss in productivity due to thermodynamic equilibrium, whereas the monolithic reactors exhibit negligible pressure drop and achieve far better performances.     

Mesh refinement for shape optimization

The numerical solution of shape optimization problems is considered. The algorithm of successive optimization based on finite element techniques and design sensitivity analysis is applied. Mesh refinement is used to improve the quality of finite element analysis and the computed numerical solution. The norm of the variation of the Lagrange augmented functional with respect to boundary variation (residuals in necessary optimality conditions) is taken as an a posteriori error estimator for optimality conditions and the Zienkiewicz—Zhu error estimator is used to improve the quality of structural analysis. The examples presented show meaningful effects obtained by means of mesh refinement with a new error estimator.