Migrating Autonomous Objects in a WAN Environment

Along with the fast progress the interconnection of computer systems makes the need for enterprise-wide distributed solutions grows. These systems have to support hundreds or even thousands of sites located all over the world. The distances between the sites will impose high communication costs on distributed activities thus significantly increasing their response times. This problem can be alleviated through migrating objects to the sites where they are needed. However, migration in such systems cannot be managed globally. Therefore, we present a migration protocol for (autonomous) objects which enables them autonomously to decide whether or not and which site to migrate to, thus making the system self-tuning. We also present two migration strategies objects can use to derive their migration decisions. The first one finds the optimal placement for an object while the second strategy in some cases returns a sub-optimal location but induces lower computation costs. The two strategies are evaluated through benchmarks in a distributed system of autonomous objects. The experiments show a significant decrease in communication costs when migration is employed.     

Cognitive clamping geometries for monitoring elastic deformation in forming machines and processes

In the context of inline monitoring and controlling of forming processes, the distribution of acting forces on tool and forming machine causing elastic deformation of the clamping surfaces provides fundamental information on the resulting part quality whereas the inline detection is still challenging. This paper presents a novel method using the T-slot geometry as a cognitive area for inline analyzing of the elastic deformation of the tool-clamping surfaces. Using a newly developed sensor device, the elastic deformation state of the T-slot geometry under process forces is detected by strain measuring of a deformation body mounted inside the T-slot. The functionality principle of the sensor device and measuring method for process monitoring are demonstrated by simulation and experiments, demonstrating the potential for process control.     

Innovative, non-stirred bioreactors in scales from milliliters up to 1000 liters for suspension cultures of cells using disposable bags and containers--a Swiss contribution

Innovative mixing principles in bioreactors, for example using the rocking of a platform to induce a backwards and forwards 'wave', or using orbital shaking to generate a 'wave' that runs round in a cylindrical container, have proved to be successful for the suspension cultures of cells, especially when combined with disposable materials. This article presents an overview of the engineering characteristics when these new principles are applied in bioreactors, and case studies covering scales of operation from milliliters to 1000 liters.     

Microwave-assisted nonaqueous sol-gel deposition of different spinel ferrites and barium titanate perovskite thin films

Rapid and selective heating of solvents by microwave irradiation coupled to nonaqueous sol-gel chemistry makes it possible to simultaneously synthesize metal oxide nanoparticles within minutes and deposit them on substrates. The simple immersion of substrates, such as glass slides, in the reaction solution results after microwave heating in the deposition of homogeneous porous thin films whose thickness can be adjusted through the precursor concentration. Here we use such a microwave-assisted nonaqueous sol-gel process for the formation of various spinel ferrite MFe2O4 (M = Fe, Co, Mn, Ni) and BaTiO3 nanoparticles and their deposition as thin films. The approach offers high flexibility with respect to controlling the crystal size by adjusting the reaction time and/or temperature. Based on the example of CoFe2O4 nanoparticles, we show how the crystal size can carefully be tuned from 4 to 8 nm, resulting in a continuous change of the magnetic properties.     

Influence of a novel castor‐oil‐derived additive on the mechanical properties and oxygen diffusivity of polystyrene

Mechanical properties, densities, and oxygen diffusion coefficients have been measured in polystyrene samples (PS) as a function of additive loading. The additive employed is based on castor oil, and is a desirable alternative to phthalates. Tensile strength measurements indicate the additive renders PS stronger at low loadings, i.e. it antiplasticizes the material. In contrast, the additive plasticizes PS at high loadings. Specific volumes and oxygen diffusion coefficients do not show this dual behavior. Rather, one observes a monotonic decrease in density and oxygen diffusivity with an increase in additive loading. This suggests that the larger segmental motions responsible for the macroscopic properties of the polymer are influenced by the additive in a different manner than the local motions and confined changes in free volume that govern the mobility of oxygen. These data indicate that antiplasticization cannot be predicted solely from diffusivity and density measurements and, vice versa, trends in diffusivity cannot be deduced from mechanical measurements alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Improvement of the intrinsic time resolving power of the Cologne iron-free orange type electron spectrometers

Conversion electron spectroscopy represents an important tool for nuclear structure analysis of medium and heavy nuclei. Two iron-free magnetic electron spectrometers of the orange type have been installed at the Institute for Nuclear Physics of the University of Cologne. The very large transmission of 15% and the very good energy resolution of 1% makes the iron-free orange spectrometer a powerful instrument. By means of fast timing techniques, lifetimes of nuclear excited states can be measured with an accuracy better than 20 ps. For the first time, the energy dependent centroid position of prompt events yielding the time-walk characteristics (the prompt curve) of the orange spectrometer fast timing setup has been measured using prompt secondary δ-electrons generated in a pulsed beam experiment. The prompt curve calibrated as a function of energy allows precise lifetime determination down to a few tens of picoseconds by the use of the centroid shift method.     

UV fluorescence lifetime imaging microscopy: a label-free method for detection and quantification of protein interactions

Due to the ability to detect multiple parameters simultaneously, protein microarrays have found widespread applications from basic biological research to diagnosis of diseases. Generally, readout of protein microarrays is performed by fluorescence detection using either dye-labeled detector antibodies or direct labeling of the target proteins. We developed a method for the label-free detection and quantification of proteins based on time-gated, wide-field, camera-based UV fluorescence lifetime imaging microscopy to gain lifetime information from each pixel of a sensitive CCD camera. The method relies on differences in the native fluorescence lifetime of proteins and takes advantage of binding-induced lifetime changes for the unequivocal detection and quantification of target proteins. Since fitting of the fluorescence decay for every pixel in an image using a classical exponential decay model is time-consuming and unstable at very low fluorescence intensities, we used a new, very robust and fast alternative method to generate UV fluorescence lifetime images by calculating the average lifetime of the decay for each pixel in the image stack using a model-free average decay time algorithm.To validate the method, we demonstrate the detection and quantification of p53 antibodies, a tumor marker in cancer diagnosis. Using tryptophan-containing capture peptides, we achieved a detection sensitivity for monoclonal antibodies down to the picomolar concentration range. The obtained affinity constant, Ka, of (1.4 +/- 0.6) x 10(9) M(-1), represents a typical value for antigen/antibody binding and is in agreement with values determined by traditional binding assays.     

Iterative image reconstruction using prior knowledge

A method is proposed to reconstruct signals from incomplete data. The method, which can be interpreted both as a discrete implementation of the so-called prior discrete Fourier transform (PDFT) spectral estimation technique and as a variant of the algebraic reconstruction technique, allows one to incorporate prior information about the reconstructed signal to improve the resolution of the signal estimated. The context of diffraction tomography and image reconstruction from samples of the far-field scattering amplitude are used to explore the performance of the method. On the basis of numerical computations, the optimum choice of parameters is determined empirically by comparing image reconstructions of the noniterative PDFT algorithm and the proposed iterative scheme.     

Lichen Substances Prevent Lichens from Nutrient Deficiency

The dibenzofuran usnic acid, a widespread cortical secondary metabolite produced by lichen-forming fungi, was shown to promote the intracellular uptake of Cu²⁺ in two epiphytic lichens, Evernia mesomorpha and Ramalina menziesii, from acidic, nutrient-poor bark. Higher Cu²⁺ uptake in the former, which produces the depside divaricatic acid in addition to usnic acid, suggests that this depside promotes Cu²⁺ uptake. Since Cu²⁺ is one of the rarest micronutrients, promotion of Cu²⁺ uptake by lichen substances may be crucial for the studied lichens to survive in their nutrient-poor habitats. In contrast, study of the uptake of other metals in E. mesomorpha revealed that the intracellular uptake of Mn²⁺, which regularly exceeds potentially toxic concentrations in leachates of acidic tree bark, was partially inhibited by the lichen substances produced by this species. Inhibition of Mn²⁺ uptake by lichen substances previously has been demonstrated in lichens. The uptake of Fe²⁺, Fe³⁺, Mg²⁺, and Zn²⁺, which fail to reach toxic concentrations in acidic bark at unpolluted sites, although they are more common than Cu²⁺, was not affected by lichen substances of E. mesomorpha.