Useful formula for moment computation of normal random variables with nonzero means

It is well known that higher order moments of normal random variables (RV) with zero means can be expressed by terms of second-order moments. In this correspondence an extension will be given for moments of normal RV with nonzero means.     

Sample preparation strategies for targeted proteomics via proteotypic peptides in human blood using liquid chromatography tandem mass spectrometry

The simultaneous quantification of protein concentrations via proteotypic peptides in human blood by liquid chromatography coupled to quadrupole MS/MS is an important field of bioanalytical research with a high potential for routine diagnostic applications. This review summarizes currently available sample preparation procedures and trends for absolute protein quantification in blood using LC-MS/MS. It discusses approaches of transferring established qualitative protocols to a quantitative analysis regarding their reliability and reproducibility. Techniques used to enhance method sensitivity such as the depletion of high-abundant proteins or the immunoaffinity enrichment of proteins and peptides are described. Furthermore, workflows for (i) protein denaturation, (ii) disulfide bridge reduction and (iii) thiol alkylation as well as (iv) enzymatic digestion for absolute protein quantification are presented. The main focus is on the tryptic digestion as a bottleneck of protein quantification via proteotypic peptides. Conclusively, requirements for a high-throughput application are discussed.     

Dynamic subset selection based on a fitness case topology

A large training set of fitness cases can critically slow down genetic programming, if no appropriate subset selection method is applied. Such a method allows an individual to be evaluated on a smaller subset of fitness cases. In this paper we suggest a new subset selection method that takes the problem structure into account, while being problem independent at the same time. In order to achieve this, information about the problem structure is acquired during evolutionary search by creating a topology (relationship) on the set of fitness cases. The topology is induced by individuals of the evolving population. This is done by increasing the strength of the relation between two fitness cases, if an individual of the population is able to solve both of them. Our new topology-based subset selection method chooses a subset, such that fitness cases in this subset are as distantly related as is possible with respect to the induced topology. We compare topology-based selection of fitness cases with dynamic subset selection and stochastic subset sampling on four different problems. On average, runs with topology-based selection show faster progress than the others.     

Software architecture awareness in long-term software product evolution

Software architecture has been established in software engineering for almost 40 years. When developing and evolving software products, architecture is expected to be even more relevant compared to contract development. However, the research results seem not to have influenced the development practice around software products very much. The architecture often only exists implicitly in discussions that accompany the development. Nonetheless many of the software products have been used for over 10, or even 20 years. How do development teams manage to accommodate changing needs and at the same time maintain the quality of the product? In order to answer this question, grounded theory study based on 15 semi-structured interviews was conducted in order to find out about the wide spectrum of architecture practices in software product developing organisations. Our results indicate that a chief architect or central developer acts as a ‘walking architecture’ devising changes and discussing local designs while at the same time updating his own knowledge about problematic aspects that need to be addressed. Architecture documentation and representations might not be used, especially if they replace the feedback from on-going developments into the ‘architecturing’ practices. Referring to results from Computer Supported Cooperative Work, we discuss how explicating the existing architecture needs to be complemented by social protocols to support the communication and knowledge sharing processes of the ‘walking architecture’.     

The microscopy cell (MicCell), a versatile modular flowthrough system for cell biology, biomaterial research, and nanotechnology

We describe a novel microfluidic perfusion system for high-resolution microscopes. Its modular design allows pre-coating of the coverslip surface with reagents, biomolecules, or cells. A poly(dimethylsiloxane) (PDMS) layer is cast in a special molding station, using masters made by photolithography and dry etching of silicon or by photoresist patterning on glass or silicon. This channel system can be reused while the coverslip is exchanged between experiments. As normal fluidic connectors are used, the link to external, computer-programmable syringe pumps is standardized and various fluidic channel networks can be used in the same setup. The system can house hydrogel microvalves and microelectrodes close to the imaging area to control the influx of reaction partners. We present a range of applications, including single-molecule analysis by fluorescence correlation spectroscopy (FCS), manipulation of single molecules for nanostructuring by hydrodynamic flow fields or the action of motor proteins, generation of concentration gradients, trapping and stretching of live cells using optical fibers precisely mounted in the PDMS layer, and the integration of microelectrodes for actuation and sensing.     

Sustainable Syngas Production by High-Temperature Co-electrolysis

High-temperature co-electrolysis shows comparable performance to steam electrolysis. Current densities above 1 A cm⁻² can be reached between 700 °C and 800 °C. Tailor-made syngas is produced, mainly determined by the reactant ratio. The experimental results are supported by modeling. Durability tests with cathode-supported cells show increased voltage degradation rates during electrolysis compared to fuel cell operation. Nickel depletion is found to be the main cause.