Softwarequalit?tsmodelle – Praxisempfehlungen und Forschungsagenda

Softwarequalit?t birgt für einen Technologiestandort wie Deutschland ein gro?es Potenzial. Sie ist aber gleichzeitig auch eine enorme Herausforderung. Qualit?tsmodelle tragen zur Konsolidierung und Konkretisierung der vielschichtigen Qualit?tsfragestellungen bei. Dieses Papier stellt als Ergebnis der Diskussionen von Qualit?tsexperten aus Forschung und Praxis dar, welche Fragestellungen in der Zukunft am dringlichsten im Bereich der Softwarequalit?tsmodelle bearbeitet werden müssen, um den Stand der Forschung und auch die Praxis entscheidend zu verbessern.     

Absorbing-like boundaries for quantum field theoretical grid simulations

We introduce a computational method that permits us to increase the interaction time for quantum mechanical and quantum field theoretical simulations of multi-particle states on a finite space–time grid. In contrast to the usual approach where the unwanted portion of the wave function close to the grid boundaries is absorbed by a potential with a negative imaginary part, this method is unitary and therefore conserves the norm of the state. This technique is based on assigning particles close to the boundary a larger effective mass (or slower speed of light) such that the particles slow down and cannot re-enter the interaction zone. The method can therefore be applied to multi-particle states for which imaginary potential methods fail.     

Ein besseres Verständnis des Lurbach-Karstsystems durch ein konzeptionelles Niederschlags-Abfluss-Modell

A parsimonious lumped-parameter rainfall-runoff model was tested to determine if it could be used to appropriately represent a karst hydrological system, the Lurbach system in Austria. Simulated and observed hydrographs of spring discharge were favorably simulated for a time period of seven years in spite of the small number of free parameters. Following this period the four year discharge records were only reproducible using strongly different parameter values. Results suggest during this period overflow to neighboring catchments and the capacity of production or routing store have strongly increased. This relationship is also observed in tracer test and baseflow recession data sets and is attributed to the likely redistributions of sediments. Such dynamic processes are rarely accounted for in rainfall-runoff models, and may cause severe prediction uncertainties. However, in the Lurbach system a parsimonious hydrological model was used successfully to characterize changes in hydrological conditions.     

Where people live and die makes a difference: Individual and geographic disparities in well-being progression at the end of life.

Life-span psychological research has long been interested in the contextual embeddedness of individual development. To examine whether and how regional variables relate to between-person disparities in the progression of late-life well-being, we applied three-level growth curve models to 24-year longitudinal data from deceased participants of the German Socio-Economic Panel Study (N = 3,427; age at death = 18 to 101 years). Results indicated steep declines in well-being with impending death, with some 8% of the between-person differences in both level and decline of well-being reflecting between-county differences. Exploratory analyses revealed that individuals living and dying in less affluent counties reported lower late-life well-being, controlling for key individual predictors, including age at death, gender, education, and household income. The regional variables examined did not directly relate to well-being change but were found to moderate (e.g., amplify) the disparities in change attributed to individual variables. Our results suggest that resource-poor counties provide relatively less fertile grounds for successful aging until the end of life and may serve to exacerbate disparities. We conclude that examinations of how individual and residential characteristics interact can further our understanding of individual psychological outcomes and suggest routes for future inquiry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Navigating with fingers and feet: Analysis of human (Homo sapiens) and rat (Rattus norvegicus) movement organization during nonvisual spatial tasks.

The current set of studies examines the contribution of movement segmentation to self-movement cue processing for estimating direction and distance to a start location in humans and rats. Experiments 1 and 2 examined the extent that ambulatory dead reckoning tasks can be adapted to the manipulatory scale in humans. Experiments 3 and 4 investigated the performance of rats in similar tasks at their ambulatory scale. Movement segmentation had differential effects on absolute heading error for humans and rats when only comparing performance on specific tasks; however, movement segmentation had similar effects for both species when performance was examined across all tasks. In general, magnitude of movement segmentation was associated with absolute heading error in both humans and rats. In contrast, both species modified homeward segment kinematics based on the distance to the start location in all tasks, consistent with the use of self-movement cues to estimate distance. The current study provides evidence for a role of movement segmentation in processing self-movement cues selective to direction estimation and develops a foundation for future studies investigating the neurobiology of spatial orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential Expression of Peroxisomal Proteins in Distinct Types of Parotid Gland Tumors

Salivary gland cancers are rare but aggressive tumors that have poor prognosis and lack effective cure. Of those, parotid tumors constitute the majority. Functioning as metabolic machinery contributing to cellular redox balance, peroxisomes have emerged as crucial players in tumorigenesis. Studies on murine and human cells have examined the role of peroxisomes in carcinogenesis with conflicting results. These studies either examined the consequences of altered peroxisomal proliferators or compared their expression in healthy and neoplastic tissues. None, however, examined such differences exclusively in human parotid tissue or extended comparison to peroxisomal proteins and their associated gene expressions. Therefore, we examined differences in peroxisomal dynamics in parotid tumors of different morphologies. Using immunofluorescence and quantitative PCR, we compared the expression levels of key peroxisomal enzymes and proliferators in healthy and neoplastic parotid tissue samples. Three parotid tumor subtypes were examined: pleomorphic adenoma, mucoepidermoid carcinoma and acinic cell carcinoma. We observed higher expression of peroxisomal matrix proteins in neoplastic samples with exceptional down regulation of certain enzymes; however, the degree of expression varied between tumor subtypes. Our findings confirm previous experimental results on other organ tissues and suggest peroxisomes as possible therapeutic targets or markers in all or certain subtypes of parotid neoplasms.     

Characterization of filter performance under low-pressure operation

Particulate gas filters are a critical element in the purification systems used to ensure defect-free manufacturing in semiconductor industry. In atomic layer deposition (ALD) processes, these filters are typically operated under sub-atmospheric pressure conditions, but their filtration characteristics are, often, only known at atmospheric pressure. In this study, performance of a metal filter that is typically used in low-pressure ALD precursor delivery systems is studied experimentally and theoretically down to 4.5 kPa. The experimental procedure was designed to minimize the presence of multiply charged particles in the test aerosol for different operating pressures and flowrates. The experimental results suggest that most penetrating particle size only slightly varies with pressure, but the shape of the penetration curve and the maximum value of the penetration changes significantly with pressure. The experimental data are used to test predictions of filter performance at low pressures made using classical theory. The comparison results suggest that the combination of classical theory and manufacturer-specified parameters results in large errors in calculated penetration values at low pressures. Accurate predictions are seen to be possible for particle Stokes numbers less than 0.1, when an inhomogenous filtration model is used in combination with effective filter parameters that are obtained from experimental measurements of filter efficiency and pressure drop at atmospheric pressures.

Copyright © 2016 American Association for Aerosol Research     

Yttrium doping of Ba0.5Sr0.5Co0.8Fe0.2O3-δ part I: Influence on oxygen permeation,electrical properties,reductive stability,and lattice parameters

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) exhibits a very high oxygen permeability in its cubic perovskite phase, making it a promising candidate for high-temperature energy-related applications such as oxygen-transport membranes. It suffers, however, from a pronounced phase instability at application-relevant temperatures below 840?°C which is presumed to result from a valence change of B-site cobalt. In an attempt to stabilize the cubic BSCF phase, monovalent Y³⁺ was doped in small concentrations (1–10?mol-% yttrium) onto its B-site. The influence of this doping on the physico-chemical properties (electrical conductivity, reductive stability, lattice constant), on the sintering behavior, and on the oxygen permeation of BSCF has been systematically investigated. Despite a slightly adverse effect to permeability (decrease in oxygen permeation by about 20–30%), a doping concentration of 10?mol-% Y is found to completely suppress secondary-phase formation and, hence, stabilize the cubic BSCF system at 800?°C. These findings are extremely promising with regard to a long-term operation of BSCF in atmospheres free of acidic impurity gases.     

Monitoring of Apoptosis in 3D Cell Cultures by FRET and Light Sheet Fluorescence Microscopy

Non-radiative cell membrane associated Förster Resonance Energy Transfer (FRET) from an enhanced cyan fluorescent protein (ECFP) to an enhanced yellow fluorescent protein (EYFP) is used for detection of apoptosis in 3-dimensional cell cultures. FRET is visualized in multi-cellular tumor spheroids by light sheet based fluorescence microscopy in combination with microspectral analysis and fluorescence lifetime imaging (FLIM). Upon application of staurosporine and to some extent after treatment with phorbol-12-myristate-13-acetate (PMA), a specific activator of protein kinase c, the caspase-3 sensitive peptide linker DEVD is cleaved. This results in a reduction of acceptor (EYFP) fluorescence as well as a prolongation of the fluorescence lifetime of the donor (ECFP). Fluorescence spectra and lifetimes may, therefore, be used for monitoring of apoptosis in a realistic 3-dimensional system, while light sheet based microscopy appears appropriate for 3D imaging at low light exposure.